1 /* Perform various loop optimizations, including strength reduction.
2 Copyright (C) 1987, 1988, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997,
3 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 /* This is the loop optimization pass of the compiler.
23 It finds invariant computations within loops and moves them
24 to the beginning of the loop. Then it identifies basic and
25 general induction variables. Strength reduction is applied to the general
26 induction variables, and induction variable elimination is applied to
27 the basic induction variables.
29 It also finds cases where
30 a register is set within the loop by zero-extending a narrower value
31 and changes these to zero the entire register once before the loop
32 and merely copy the low part within the loop.
34 Most of the complexity is in heuristics to decide when it is worth
35 while to do these things. */
44 #include "hard-reg-set.h"
45 #include "basic-block.h"
46 #include "insn-config.h"
56 #include "insn-flags.h"
59 /* Not really meaningful values, but at least something. */
60 #ifndef SIMULTANEOUS_PREFETCHES
61 #define SIMULTANEOUS_PREFETCHES 3
63 #ifndef PREFETCH_BLOCK
64 #define PREFETCH_BLOCK 32
67 #define HAVE_prefetch 0
68 #define CODE_FOR_prefetch 0
69 #define gen_prefetch(a,b,c) (abort(), NULL_RTX)
72 /* Give up the prefetch optimizations once we exceed a given threshhold.
73 It is unlikely that we would be able to optimize something in a loop
74 with so many detected prefetches. */
75 #define MAX_PREFETCHES 100
76 /* The number of prefetch blocks that are beneficial to fetch at once before
77 a loop with a known (and low) iteration count. */
78 #define PREFETCH_BLOCKS_BEFORE_LOOP_MAX 6
79 /* For very tiny loops it is not worthwhile to prefetch even before the loop,
80 since it is likely that the data are already in the cache. */
81 #define PREFETCH_BLOCKS_BEFORE_LOOP_MIN 2
82 /* The minimal number of prefetch blocks that a loop must consume to make
83 the emitting of prefetch instruction in the body of loop worthwhile. */
84 #define PREFETCH_BLOCKS_IN_LOOP_MIN 6
86 /* Parameterize some prefetch heuristics so they can be turned on and off
87 easily for performance testing on new architecures. These can be
88 defined in target-dependent files. */
90 /* Prefetch is worthwhile only when loads/stores are dense. */
91 #ifndef PREFETCH_ONLY_DENSE_MEM
92 #define PREFETCH_ONLY_DENSE_MEM 1
95 /* Define what we mean by "dense" loads and stores; This value divided by 256
96 is the minimum percentage of memory references that worth prefetching. */
97 #ifndef PREFETCH_DENSE_MEM
98 #define PREFETCH_DENSE_MEM 220
101 /* Do not prefetch for a loop whose iteration count is known to be low. */
102 #ifndef PREFETCH_NO_LOW_LOOPCNT
103 #define PREFETCH_NO_LOW_LOOPCNT 1
106 /* Define what we mean by a "low" iteration count. */
107 #ifndef PREFETCH_LOW_LOOPCNT
108 #define PREFETCH_LOW_LOOPCNT 32
111 /* Do not prefetch for a loop that contains a function call; such a loop is
112 probably not an internal loop. */
113 #ifndef PREFETCH_NO_CALL
114 #define PREFETCH_NO_CALL 1
117 /* Do not prefetch accesses with an extreme stride. */
118 #ifndef PREFETCH_NO_EXTREME_STRIDE
119 #define PREFETCH_NO_EXTREME_STRIDE 1
122 /* Define what we mean by an "extreme" stride. */
123 #ifndef PREFETCH_EXTREME_STRIDE
124 #define PREFETCH_EXTREME_STRIDE 4096
127 /* Do not handle reversed order prefetches (negative stride). */
128 #ifndef PREFETCH_NO_REVERSE_ORDER
129 #define PREFETCH_NO_REVERSE_ORDER 1
132 /* Prefetch even if the GIV is not always executed. */
133 #ifndef PREFETCH_NOT_ALWAYS
134 #define PREFETCH_NOT_ALWAYS 0
137 /* If the loop requires more prefetches than the target can process in
138 parallel then don't prefetch anything in that loop. */
139 #ifndef PREFETCH_LIMIT_TO_SIMULTANEOUS
140 #define PREFETCH_LIMIT_TO_SIMULTANEOUS 1
143 #define LOOP_REG_LIFETIME(LOOP, REGNO) \
144 ((REGNO_LAST_LUID (REGNO) - REGNO_FIRST_LUID (REGNO)))
146 #define LOOP_REG_GLOBAL_P(LOOP, REGNO) \
147 ((REGNO_LAST_LUID (REGNO) > INSN_LUID ((LOOP)->end) \
148 || REGNO_FIRST_LUID (REGNO) < INSN_LUID ((LOOP)->start)))
150 #define LOOP_REGNO_NREGS(REGNO, SET_DEST) \
151 ((REGNO) < FIRST_PSEUDO_REGISTER \
152 ? HARD_REGNO_NREGS ((REGNO), GET_MODE (SET_DEST)) : 1)
155 /* Vector mapping INSN_UIDs to luids.
156 The luids are like uids but increase monotonically always.
157 We use them to see whether a jump comes from outside a given loop. */
161 /* Indexed by INSN_UID, contains the ordinal giving the (innermost) loop
162 number the insn is contained in. */
164 struct loop
**uid_loop
;
166 /* 1 + largest uid of any insn. */
168 int max_uid_for_loop
;
170 /* 1 + luid of last insn. */
174 /* Number of loops detected in current function. Used as index to the
177 static int max_loop_num
;
179 /* Bound on pseudo register number before loop optimization.
180 A pseudo has valid regscan info if its number is < max_reg_before_loop. */
181 unsigned int max_reg_before_loop
;
183 /* The value to pass to the next call of reg_scan_update. */
184 static int loop_max_reg
;
186 #define obstack_chunk_alloc xmalloc
187 #define obstack_chunk_free free
189 /* During the analysis of a loop, a chain of `struct movable's
190 is made to record all the movable insns found.
191 Then the entire chain can be scanned to decide which to move. */
195 rtx insn
; /* A movable insn */
196 rtx set_src
; /* The expression this reg is set from. */
197 rtx set_dest
; /* The destination of this SET. */
198 rtx dependencies
; /* When INSN is libcall, this is an EXPR_LIST
199 of any registers used within the LIBCALL. */
200 int consec
; /* Number of consecutive following insns
201 that must be moved with this one. */
202 unsigned int regno
; /* The register it sets */
203 short lifetime
; /* lifetime of that register;
204 may be adjusted when matching movables
205 that load the same value are found. */
206 short savings
; /* Number of insns we can move for this reg,
207 including other movables that force this
208 or match this one. */
209 unsigned int cond
: 1; /* 1 if only conditionally movable */
210 unsigned int force
: 1; /* 1 means MUST move this insn */
211 unsigned int global
: 1; /* 1 means reg is live outside this loop */
212 /* If PARTIAL is 1, GLOBAL means something different:
213 that the reg is live outside the range from where it is set
214 to the following label. */
215 unsigned int done
: 1; /* 1 inhibits further processing of this */
217 unsigned int partial
: 1; /* 1 means this reg is used for zero-extending.
218 In particular, moving it does not make it
220 unsigned int move_insn
: 1; /* 1 means that we call emit_move_insn to
221 load SRC, rather than copying INSN. */
222 unsigned int move_insn_first
:1;/* Same as above, if this is necessary for the
223 first insn of a consecutive sets group. */
224 unsigned int is_equiv
: 1; /* 1 means a REG_EQUIV is present on INSN. */
225 enum machine_mode savemode
; /* Nonzero means it is a mode for a low part
226 that we should avoid changing when clearing
227 the rest of the reg. */
228 struct movable
*match
; /* First entry for same value */
229 struct movable
*forces
; /* An insn that must be moved if this is */
230 struct movable
*next
;
234 FILE *loop_dump_stream
;
236 /* Forward declarations. */
238 static void find_and_verify_loops
PARAMS ((rtx
, struct loops
*));
239 static void mark_loop_jump
PARAMS ((rtx
, struct loop
*));
240 static void prescan_loop
PARAMS ((struct loop
*));
241 static int reg_in_basic_block_p
PARAMS ((rtx
, rtx
));
242 static int consec_sets_invariant_p
PARAMS ((const struct loop
*,
244 static int labels_in_range_p
PARAMS ((rtx
, int));
245 static void count_one_set
PARAMS ((struct loop_regs
*, rtx
, rtx
, rtx
*));
246 static void note_addr_stored
PARAMS ((rtx
, rtx
, void *));
247 static void note_set_pseudo_multiple_uses
PARAMS ((rtx
, rtx
, void *));
248 static int loop_reg_used_before_p
PARAMS ((const struct loop
*, rtx
, rtx
));
249 static void scan_loop
PARAMS ((struct loop
*, int));
251 static void replace_call_address
PARAMS ((rtx
, rtx
, rtx
));
253 static rtx skip_consec_insns
PARAMS ((rtx
, int));
254 static int libcall_benefit
PARAMS ((rtx
));
255 static void ignore_some_movables
PARAMS ((struct loop_movables
*));
256 static void force_movables
PARAMS ((struct loop_movables
*));
257 static void combine_movables
PARAMS ((struct loop_movables
*,
258 struct loop_regs
*));
259 static int num_unmoved_movables
PARAMS ((const struct loop
*));
260 static int regs_match_p
PARAMS ((rtx
, rtx
, struct loop_movables
*));
261 static int rtx_equal_for_loop_p
PARAMS ((rtx
, rtx
, struct loop_movables
*,
262 struct loop_regs
*));
263 static void add_label_notes
PARAMS ((rtx
, rtx
));
264 static void move_movables
PARAMS ((struct loop
*loop
, struct loop_movables
*,
266 static void loop_movables_add
PARAMS((struct loop_movables
*,
268 static void loop_movables_free
PARAMS((struct loop_movables
*));
269 static int count_nonfixed_reads
PARAMS ((const struct loop
*, rtx
));
270 static void loop_bivs_find
PARAMS((struct loop
*));
271 static void loop_bivs_init_find
PARAMS((struct loop
*));
272 static void loop_bivs_check
PARAMS((struct loop
*));
273 static void loop_givs_find
PARAMS((struct loop
*));
274 static void loop_givs_check
PARAMS((struct loop
*));
275 static int loop_biv_eliminable_p
PARAMS((struct loop
*, struct iv_class
*,
277 static int loop_giv_reduce_benefit
PARAMS((struct loop
*, struct iv_class
*,
278 struct induction
*, rtx
));
279 static void loop_givs_dead_check
PARAMS((struct loop
*, struct iv_class
*));
280 static void loop_givs_reduce
PARAMS((struct loop
*, struct iv_class
*));
281 static void loop_givs_rescan
PARAMS((struct loop
*, struct iv_class
*,
283 static void loop_ivs_free
PARAMS((struct loop
*));
284 static void strength_reduce
PARAMS ((struct loop
*, int));
285 static void find_single_use_in_loop
PARAMS ((struct loop_regs
*, rtx
, rtx
));
286 static int valid_initial_value_p
PARAMS ((rtx
, rtx
, int, rtx
));
287 static void find_mem_givs
PARAMS ((const struct loop
*, rtx
, rtx
, int, int));
288 static void record_biv
PARAMS ((struct loop
*, struct induction
*,
289 rtx
, rtx
, rtx
, rtx
, rtx
*,
291 static void check_final_value
PARAMS ((const struct loop
*,
292 struct induction
*));
293 static void loop_ivs_dump
PARAMS((const struct loop
*, FILE *, int));
294 static void loop_iv_class_dump
PARAMS((const struct iv_class
*, FILE *, int));
295 static void loop_biv_dump
PARAMS((const struct induction
*, FILE *, int));
296 static void loop_giv_dump
PARAMS((const struct induction
*, FILE *, int));
297 static void record_giv
PARAMS ((const struct loop
*, struct induction
*,
298 rtx
, rtx
, rtx
, rtx
, rtx
, rtx
, int,
299 enum g_types
, int, int, rtx
*));
300 static void update_giv_derive
PARAMS ((const struct loop
*, rtx
));
301 static void check_ext_dependent_givs
PARAMS ((struct iv_class
*,
302 struct loop_info
*));
303 static int basic_induction_var
PARAMS ((const struct loop
*, rtx
,
304 enum machine_mode
, rtx
, rtx
,
305 rtx
*, rtx
*, rtx
**));
306 static rtx simplify_giv_expr
PARAMS ((const struct loop
*, rtx
, rtx
*, int *));
307 static int general_induction_var
PARAMS ((const struct loop
*loop
, rtx
, rtx
*,
308 rtx
*, rtx
*, rtx
*, int, int *,
310 static int consec_sets_giv
PARAMS ((const struct loop
*, int, rtx
,
311 rtx
, rtx
, rtx
*, rtx
*, rtx
*, rtx
*));
312 static int check_dbra_loop
PARAMS ((struct loop
*, int));
313 static rtx express_from_1
PARAMS ((rtx
, rtx
, rtx
));
314 static rtx combine_givs_p
PARAMS ((struct induction
*, struct induction
*));
315 static int cmp_combine_givs_stats
PARAMS ((const PTR
, const PTR
));
316 static void combine_givs
PARAMS ((struct loop_regs
*, struct iv_class
*));
317 static int product_cheap_p
PARAMS ((rtx
, rtx
));
318 static int maybe_eliminate_biv
PARAMS ((const struct loop
*, struct iv_class
*,
320 static int maybe_eliminate_biv_1
PARAMS ((const struct loop
*, rtx
, rtx
,
321 struct iv_class
*, int,
323 static int last_use_this_basic_block
PARAMS ((rtx
, rtx
));
324 static void record_initial
PARAMS ((rtx
, rtx
, void *));
325 static void update_reg_last_use
PARAMS ((rtx
, rtx
));
326 static rtx next_insn_in_loop
PARAMS ((const struct loop
*, rtx
));
327 static void loop_regs_scan
PARAMS ((const struct loop
*, int));
328 static int count_insns_in_loop
PARAMS ((const struct loop
*));
329 static void load_mems
PARAMS ((const struct loop
*));
330 static int insert_loop_mem
PARAMS ((rtx
*, void *));
331 static int replace_loop_mem
PARAMS ((rtx
*, void *));
332 static void replace_loop_mems
PARAMS ((rtx
, rtx
, rtx
));
333 static int replace_loop_reg
PARAMS ((rtx
*, void *));
334 static void replace_loop_regs
PARAMS ((rtx insn
, rtx
, rtx
));
335 static void note_reg_stored
PARAMS ((rtx
, rtx
, void *));
336 static void try_copy_prop
PARAMS ((const struct loop
*, rtx
, unsigned int));
337 static void try_swap_copy_prop
PARAMS ((const struct loop
*, rtx
,
339 static int replace_label
PARAMS ((rtx
*, void *));
340 static rtx check_insn_for_givs
PARAMS((struct loop
*, rtx
, int, int));
341 static rtx check_insn_for_bivs
PARAMS((struct loop
*, rtx
, int, int));
342 static rtx gen_add_mult
PARAMS ((rtx
, rtx
, rtx
, rtx
));
343 static void loop_regs_update
PARAMS ((const struct loop
*, rtx
));
344 static int iv_add_mult_cost
PARAMS ((rtx
, rtx
, rtx
, rtx
));
346 static rtx loop_insn_emit_after
PARAMS((const struct loop
*, basic_block
,
348 static rtx loop_call_insn_emit_before
PARAMS((const struct loop
*,
349 basic_block
, rtx
, rtx
));
350 static rtx loop_call_insn_hoist
PARAMS((const struct loop
*, rtx
));
351 static rtx loop_insn_sink_or_swim
PARAMS((const struct loop
*, rtx
));
353 static void loop_dump_aux
PARAMS ((const struct loop
*, FILE *, int));
354 static void loop_delete_insns
PARAMS ((rtx
, rtx
));
355 static HOST_WIDE_INT remove_constant_addition
PARAMS ((rtx
*));
356 void debug_ivs
PARAMS ((const struct loop
*));
357 void debug_iv_class
PARAMS ((const struct iv_class
*));
358 void debug_biv
PARAMS ((const struct induction
*));
359 void debug_giv
PARAMS ((const struct induction
*));
360 void debug_loop
PARAMS ((const struct loop
*));
361 void debug_loops
PARAMS ((const struct loops
*));
363 typedef struct rtx_pair
369 typedef struct loop_replace_args
376 /* Nonzero iff INSN is between START and END, inclusive. */
377 #define INSN_IN_RANGE_P(INSN, START, END) \
378 (INSN_UID (INSN) < max_uid_for_loop \
379 && INSN_LUID (INSN) >= INSN_LUID (START) \
380 && INSN_LUID (INSN) <= INSN_LUID (END))
382 /* Indirect_jump_in_function is computed once per function. */
383 static int indirect_jump_in_function
;
384 static int indirect_jump_in_function_p
PARAMS ((rtx
));
386 static int compute_luids
PARAMS ((rtx
, rtx
, int));
388 static int biv_elimination_giv_has_0_offset
PARAMS ((struct induction
*,
392 /* Benefit penalty, if a giv is not replaceable, i.e. must emit an insn to
393 copy the value of the strength reduced giv to its original register. */
394 static int copy_cost
;
396 /* Cost of using a register, to normalize the benefits of a giv. */
397 static int reg_address_cost
;
402 rtx reg
= gen_rtx_REG (word_mode
, LAST_VIRTUAL_REGISTER
+ 1);
404 reg_address_cost
= address_cost (reg
, SImode
);
406 copy_cost
= COSTS_N_INSNS (1);
409 /* Compute the mapping from uids to luids.
410 LUIDs are numbers assigned to insns, like uids,
411 except that luids increase monotonically through the code.
412 Start at insn START and stop just before END. Assign LUIDs
413 starting with PREV_LUID + 1. Return the last assigned LUID + 1. */
415 compute_luids (start
, end
, prev_luid
)
422 for (insn
= start
, i
= prev_luid
; insn
!= end
; insn
= NEXT_INSN (insn
))
424 if (INSN_UID (insn
) >= max_uid_for_loop
)
426 /* Don't assign luids to line-number NOTEs, so that the distance in
427 luids between two insns is not affected by -g. */
428 if (GET_CODE (insn
) != NOTE
429 || NOTE_LINE_NUMBER (insn
) <= 0)
430 uid_luid
[INSN_UID (insn
)] = ++i
;
432 /* Give a line number note the same luid as preceding insn. */
433 uid_luid
[INSN_UID (insn
)] = i
;
438 /* Entry point of this file. Perform loop optimization
439 on the current function. F is the first insn of the function
440 and DUMPFILE is a stream for output of a trace of actions taken
441 (or 0 if none should be output). */
444 loop_optimize (f
, dumpfile
, flags
)
445 /* f is the first instruction of a chain of insns for one function */
452 struct loops loops_data
;
453 struct loops
*loops
= &loops_data
;
454 struct loop_info
*loops_info
;
456 loop_dump_stream
= dumpfile
;
458 init_recog_no_volatile ();
460 max_reg_before_loop
= max_reg_num ();
461 loop_max_reg
= max_reg_before_loop
;
465 /* Count the number of loops. */
468 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
470 if (GET_CODE (insn
) == NOTE
471 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
475 /* Don't waste time if no loops. */
476 if (max_loop_num
== 0)
479 loops
->num
= max_loop_num
;
481 /* Get size to use for tables indexed by uids.
482 Leave some space for labels allocated by find_and_verify_loops. */
483 max_uid_for_loop
= get_max_uid () + 1 + max_loop_num
* 32;
485 uid_luid
= (int *) xcalloc (max_uid_for_loop
, sizeof (int));
486 uid_loop
= (struct loop
**) xcalloc (max_uid_for_loop
,
487 sizeof (struct loop
*));
489 /* Allocate storage for array of loops. */
490 loops
->array
= (struct loop
*)
491 xcalloc (loops
->num
, sizeof (struct loop
));
493 /* Find and process each loop.
494 First, find them, and record them in order of their beginnings. */
495 find_and_verify_loops (f
, loops
);
497 /* Allocate and initialize auxiliary loop information. */
498 loops_info
= xcalloc (loops
->num
, sizeof (struct loop_info
));
499 for (i
= 0; i
< loops
->num
; i
++)
500 loops
->array
[i
].aux
= loops_info
+ i
;
502 /* Now find all register lifetimes. This must be done after
503 find_and_verify_loops, because it might reorder the insns in the
505 reg_scan (f
, max_reg_before_loop
, 1);
507 /* This must occur after reg_scan so that registers created by gcse
508 will have entries in the register tables.
510 We could have added a call to reg_scan after gcse_main in toplev.c,
511 but moving this call to init_alias_analysis is more efficient. */
512 init_alias_analysis ();
514 /* See if we went too far. Note that get_max_uid already returns
515 one more that the maximum uid of all insn. */
516 if (get_max_uid () > max_uid_for_loop
)
518 /* Now reset it to the actual size we need. See above. */
519 max_uid_for_loop
= get_max_uid ();
521 /* find_and_verify_loops has already called compute_luids, but it
522 might have rearranged code afterwards, so we need to recompute
524 max_luid
= compute_luids (f
, NULL_RTX
, 0);
526 /* Don't leave gaps in uid_luid for insns that have been
527 deleted. It is possible that the first or last insn
528 using some register has been deleted by cross-jumping.
529 Make sure that uid_luid for that former insn's uid
530 points to the general area where that insn used to be. */
531 for (i
= 0; i
< max_uid_for_loop
; i
++)
533 uid_luid
[0] = uid_luid
[i
];
534 if (uid_luid
[0] != 0)
537 for (i
= 0; i
< max_uid_for_loop
; i
++)
538 if (uid_luid
[i
] == 0)
539 uid_luid
[i
] = uid_luid
[i
- 1];
541 /* Determine if the function has indirect jump. On some systems
542 this prevents low overhead loop instructions from being used. */
543 indirect_jump_in_function
= indirect_jump_in_function_p (f
);
545 /* Now scan the loops, last ones first, since this means inner ones are done
546 before outer ones. */
547 for (i
= max_loop_num
- 1; i
>= 0; i
--)
549 struct loop
*loop
= &loops
->array
[i
];
551 if (! loop
->invalid
&& loop
->end
)
552 scan_loop (loop
, flags
);
555 /* If there were lexical blocks inside the loop, they have been
556 replicated. We will now have more than one NOTE_INSN_BLOCK_BEG
557 and NOTE_INSN_BLOCK_END for each such block. We must duplicate
558 the BLOCKs as well. */
559 if (write_symbols
!= NO_DEBUG
)
562 end_alias_analysis ();
571 /* Returns the next insn, in execution order, after INSN. START and
572 END are the NOTE_INSN_LOOP_BEG and NOTE_INSN_LOOP_END for the loop,
573 respectively. LOOP->TOP, if non-NULL, is the top of the loop in the
574 insn-stream; it is used with loops that are entered near the
578 next_insn_in_loop (loop
, insn
)
579 const struct loop
*loop
;
582 insn
= NEXT_INSN (insn
);
584 if (insn
== loop
->end
)
587 /* Go to the top of the loop, and continue there. */
594 if (insn
== loop
->scan_start
)
601 /* Optimize one loop described by LOOP. */
603 /* ??? Could also move memory writes out of loops if the destination address
604 is invariant, the source is invariant, the memory write is not volatile,
605 and if we can prove that no read inside the loop can read this address
606 before the write occurs. If there is a read of this address after the
607 write, then we can also mark the memory read as invariant. */
610 scan_loop (loop
, flags
)
614 struct loop_info
*loop_info
= LOOP_INFO (loop
);
615 struct loop_regs
*regs
= LOOP_REGS (loop
);
617 rtx loop_start
= loop
->start
;
618 rtx loop_end
= loop
->end
;
620 /* 1 if we are scanning insns that could be executed zero times. */
622 /* 1 if we are scanning insns that might never be executed
623 due to a subroutine call which might exit before they are reached. */
625 /* Jump insn that enters the loop, or 0 if control drops in. */
626 rtx loop_entry_jump
= 0;
627 /* Number of insns in the loop. */
630 rtx temp
, update_start
, update_end
;
631 /* The SET from an insn, if it is the only SET in the insn. */
633 /* Chain describing insns movable in current loop. */
634 struct loop_movables
*movables
= LOOP_MOVABLES (loop
);
635 /* Ratio of extra register life span we can justify
636 for saving an instruction. More if loop doesn't call subroutines
637 since in that case saving an insn makes more difference
638 and more registers are available. */
640 /* Nonzero if we are scanning instructions in a sub-loop. */
648 /* Determine whether this loop starts with a jump down to a test at
649 the end. This will occur for a small number of loops with a test
650 that is too complex to duplicate in front of the loop.
652 We search for the first insn or label in the loop, skipping NOTEs.
653 However, we must be careful not to skip past a NOTE_INSN_LOOP_BEG
654 (because we might have a loop executed only once that contains a
655 loop which starts with a jump to its exit test) or a NOTE_INSN_LOOP_END
656 (in case we have a degenerate loop).
658 Note that if we mistakenly think that a loop is entered at the top
659 when, in fact, it is entered at the exit test, the only effect will be
660 slightly poorer optimization. Making the opposite error can generate
661 incorrect code. Since very few loops now start with a jump to the
662 exit test, the code here to detect that case is very conservative. */
664 for (p
= NEXT_INSN (loop_start
);
666 && GET_CODE (p
) != CODE_LABEL
&& ! INSN_P (p
)
667 && (GET_CODE (p
) != NOTE
668 || (NOTE_LINE_NUMBER (p
) != NOTE_INSN_LOOP_BEG
669 && NOTE_LINE_NUMBER (p
) != NOTE_INSN_LOOP_END
));
673 loop
->scan_start
= p
;
675 /* If loop end is the end of the current function, then emit a
676 NOTE_INSN_DELETED after loop_end and set loop->sink to the dummy
677 note insn. This is the position we use when sinking insns out of
679 if (NEXT_INSN (loop
->end
) != 0)
680 loop
->sink
= NEXT_INSN (loop
->end
);
682 loop
->sink
= emit_note_after (NOTE_INSN_DELETED
, loop
->end
);
684 /* Set up variables describing this loop. */
686 threshold
= (loop_info
->has_call
? 1 : 2) * (1 + n_non_fixed_regs
);
688 /* If loop has a jump before the first label,
689 the true entry is the target of that jump.
690 Start scan from there.
691 But record in LOOP->TOP the place where the end-test jumps
692 back to so we can scan that after the end of the loop. */
693 if (GET_CODE (p
) == JUMP_INSN
)
697 /* Loop entry must be unconditional jump (and not a RETURN) */
698 if (any_uncondjump_p (p
)
699 && JUMP_LABEL (p
) != 0
700 /* Check to see whether the jump actually
701 jumps out of the loop (meaning it's no loop).
702 This case can happen for things like
703 do {..} while (0). If this label was generated previously
704 by loop, we can't tell anything about it and have to reject
706 && INSN_IN_RANGE_P (JUMP_LABEL (p
), loop_start
, loop_end
))
708 loop
->top
= next_label (loop
->scan_start
);
709 loop
->scan_start
= JUMP_LABEL (p
);
713 /* If LOOP->SCAN_START was an insn created by loop, we don't know its luid
714 as required by loop_reg_used_before_p. So skip such loops. (This
715 test may never be true, but it's best to play it safe.)
717 Also, skip loops where we do not start scanning at a label. This
718 test also rejects loops starting with a JUMP_INSN that failed the
721 if (INSN_UID (loop
->scan_start
) >= max_uid_for_loop
722 || GET_CODE (loop
->scan_start
) != CODE_LABEL
)
724 if (loop_dump_stream
)
725 fprintf (loop_dump_stream
, "\nLoop from %d to %d is phony.\n\n",
726 INSN_UID (loop_start
), INSN_UID (loop_end
));
730 /* Allocate extra space for REGs that might be created by load_mems.
731 We allocate a little extra slop as well, in the hopes that we
732 won't have to reallocate the regs array. */
733 loop_regs_scan (loop
, loop_info
->mems_idx
+ 16);
734 insn_count
= count_insns_in_loop (loop
);
736 if (loop_dump_stream
)
738 fprintf (loop_dump_stream
, "\nLoop from %d to %d: %d real insns.\n",
739 INSN_UID (loop_start
), INSN_UID (loop_end
), insn_count
);
741 fprintf (loop_dump_stream
, "Continue at insn %d.\n",
742 INSN_UID (loop
->cont
));
745 /* Scan through the loop finding insns that are safe to move.
746 Set REGS->ARRAY[I].SET_IN_LOOP negative for the reg I being set, so that
747 this reg will be considered invariant for subsequent insns.
748 We consider whether subsequent insns use the reg
749 in deciding whether it is worth actually moving.
751 MAYBE_NEVER is nonzero if we have passed a conditional jump insn
752 and therefore it is possible that the insns we are scanning
753 would never be executed. At such times, we must make sure
754 that it is safe to execute the insn once instead of zero times.
755 When MAYBE_NEVER is 0, all insns will be executed at least once
756 so that is not a problem. */
758 for (p
= next_insn_in_loop (loop
, loop
->scan_start
);
760 p
= next_insn_in_loop (loop
, p
))
762 if (GET_CODE (p
) == INSN
763 && (set
= single_set (p
))
764 && GET_CODE (SET_DEST (set
)) == REG
765 #ifdef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
766 && SET_DEST (set
) != pic_offset_table_rtx
768 && ! regs
->array
[REGNO (SET_DEST (set
))].may_not_optimize
)
773 rtx src
= SET_SRC (set
);
774 rtx dependencies
= 0;
776 /* Figure out what to use as a source of this insn. If a REG_EQUIV
777 note is given or if a REG_EQUAL note with a constant operand is
778 specified, use it as the source and mark that we should move
779 this insn by calling emit_move_insn rather that duplicating the
782 Otherwise, only use the REG_EQUAL contents if a REG_RETVAL note
784 temp
= find_reg_note (p
, REG_EQUIV
, NULL_RTX
);
786 src
= XEXP (temp
, 0), move_insn
= 1;
789 temp
= find_reg_note (p
, REG_EQUAL
, NULL_RTX
);
790 if (temp
&& CONSTANT_P (XEXP (temp
, 0)))
791 src
= XEXP (temp
, 0), move_insn
= 1;
792 if (temp
&& find_reg_note (p
, REG_RETVAL
, NULL_RTX
))
794 src
= XEXP (temp
, 0);
795 /* A libcall block can use regs that don't appear in
796 the equivalent expression. To move the libcall,
797 we must move those regs too. */
798 dependencies
= libcall_other_reg (p
, src
);
802 /* For parallels, add any possible uses to the depencies, as we can't move
803 the insn without resolving them first. */
804 if (GET_CODE (PATTERN (p
)) == PARALLEL
)
806 for (i
= 0; i
< XVECLEN (PATTERN (p
), 0); i
++)
808 rtx x
= XVECEXP (PATTERN (p
), 0, i
);
809 if (GET_CODE (x
) == USE
)
810 dependencies
= gen_rtx_EXPR_LIST (VOIDmode
, XEXP (x
, 0), dependencies
);
814 /* Don't try to optimize a register that was made
815 by loop-optimization for an inner loop.
816 We don't know its life-span, so we can't compute the benefit. */
817 if (REGNO (SET_DEST (set
)) >= max_reg_before_loop
)
819 else if (/* The register is used in basic blocks other
820 than the one where it is set (meaning that
821 something after this point in the loop might
822 depend on its value before the set). */
823 ! reg_in_basic_block_p (p
, SET_DEST (set
))
824 /* And the set is not guaranteed to be executed once
825 the loop starts, or the value before the set is
826 needed before the set occurs...
828 ??? Note we have quadratic behaviour here, mitigated
829 by the fact that the previous test will often fail for
830 large loops. Rather than re-scanning the entire loop
831 each time for register usage, we should build tables
832 of the register usage and use them here instead. */
834 || loop_reg_used_before_p (loop
, set
, p
)))
835 /* It is unsafe to move the set.
837 This code used to consider it OK to move a set of a variable
838 which was not created by the user and not used in an exit test.
839 That behavior is incorrect and was removed. */
841 else if ((tem
= loop_invariant_p (loop
, src
))
842 && (dependencies
== 0
843 || (tem2
= loop_invariant_p (loop
, dependencies
)) != 0)
844 && (regs
->array
[REGNO (SET_DEST (set
))].set_in_loop
== 1
846 = consec_sets_invariant_p
847 (loop
, SET_DEST (set
),
848 regs
->array
[REGNO (SET_DEST (set
))].set_in_loop
,
850 /* If the insn can cause a trap (such as divide by zero),
851 can't move it unless it's guaranteed to be executed
852 once loop is entered. Even a function call might
853 prevent the trap insn from being reached
854 (since it might exit!) */
855 && ! ((maybe_never
|| call_passed
)
856 && may_trap_p (src
)))
859 int regno
= REGNO (SET_DEST (set
));
861 /* A potential lossage is where we have a case where two insns
862 can be combined as long as they are both in the loop, but
863 we move one of them outside the loop. For large loops,
864 this can lose. The most common case of this is the address
865 of a function being called.
867 Therefore, if this register is marked as being used exactly
868 once if we are in a loop with calls (a "large loop"), see if
869 we can replace the usage of this register with the source
870 of this SET. If we can, delete this insn.
872 Don't do this if P has a REG_RETVAL note or if we have
873 SMALL_REGISTER_CLASSES and SET_SRC is a hard register. */
875 if (loop_info
->has_call
876 && regs
->array
[regno
].single_usage
!= 0
877 && regs
->array
[regno
].single_usage
!= const0_rtx
878 && REGNO_FIRST_UID (regno
) == INSN_UID (p
)
879 && (REGNO_LAST_UID (regno
)
880 == INSN_UID (regs
->array
[regno
].single_usage
))
881 && regs
->array
[regno
].set_in_loop
== 1
882 && GET_CODE (SET_SRC (set
)) != ASM_OPERANDS
883 && ! side_effects_p (SET_SRC (set
))
884 && ! find_reg_note (p
, REG_RETVAL
, NULL_RTX
)
885 && (! SMALL_REGISTER_CLASSES
886 || (! (GET_CODE (SET_SRC (set
)) == REG
887 && REGNO (SET_SRC (set
)) < FIRST_PSEUDO_REGISTER
)))
888 /* This test is not redundant; SET_SRC (set) might be
889 a call-clobbered register and the life of REGNO
890 might span a call. */
891 && ! modified_between_p (SET_SRC (set
), p
,
892 regs
->array
[regno
].single_usage
)
893 && no_labels_between_p (p
, regs
->array
[regno
].single_usage
)
894 && validate_replace_rtx (SET_DEST (set
), SET_SRC (set
),
895 regs
->array
[regno
].single_usage
))
897 /* Replace any usage in a REG_EQUAL note. Must copy the
898 new source, so that we don't get rtx sharing between the
899 SET_SOURCE and REG_NOTES of insn p. */
900 REG_NOTES (regs
->array
[regno
].single_usage
)
901 = replace_rtx (REG_NOTES (regs
->array
[regno
].single_usage
),
902 SET_DEST (set
), copy_rtx (SET_SRC (set
)));
905 for (i
= 0; i
< LOOP_REGNO_NREGS (regno
, SET_DEST (set
)); i
++)
906 regs
->array
[regno
+i
].set_in_loop
= 0;
910 m
= (struct movable
*) xmalloc (sizeof (struct movable
));
914 m
->dependencies
= dependencies
;
915 m
->set_dest
= SET_DEST (set
);
917 m
->consec
= regs
->array
[REGNO (SET_DEST (set
))].set_in_loop
- 1;
921 m
->move_insn
= move_insn
;
922 m
->move_insn_first
= 0;
923 m
->is_equiv
= (find_reg_note (p
, REG_EQUIV
, NULL_RTX
) != 0);
924 m
->savemode
= VOIDmode
;
926 /* Set M->cond if either loop_invariant_p
927 or consec_sets_invariant_p returned 2
928 (only conditionally invariant). */
929 m
->cond
= ((tem
| tem1
| tem2
) > 1);
930 m
->global
= LOOP_REG_GLOBAL_P (loop
, regno
);
932 m
->lifetime
= LOOP_REG_LIFETIME (loop
, regno
);
933 m
->savings
= regs
->array
[regno
].n_times_set
;
934 if (find_reg_note (p
, REG_RETVAL
, NULL_RTX
))
935 m
->savings
+= libcall_benefit (p
);
936 for (i
= 0; i
< LOOP_REGNO_NREGS (regno
, SET_DEST (set
)); i
++)
937 regs
->array
[regno
+i
].set_in_loop
= move_insn
? -2 : -1;
938 /* Add M to the end of the chain MOVABLES. */
939 loop_movables_add (movables
, m
);
943 /* It is possible for the first instruction to have a
944 REG_EQUAL note but a non-invariant SET_SRC, so we must
945 remember the status of the first instruction in case
946 the last instruction doesn't have a REG_EQUAL note. */
947 m
->move_insn_first
= m
->move_insn
;
949 /* Skip this insn, not checking REG_LIBCALL notes. */
950 p
= next_nonnote_insn (p
);
951 /* Skip the consecutive insns, if there are any. */
952 p
= skip_consec_insns (p
, m
->consec
);
953 /* Back up to the last insn of the consecutive group. */
954 p
= prev_nonnote_insn (p
);
956 /* We must now reset m->move_insn, m->is_equiv, and possibly
957 m->set_src to correspond to the effects of all the
959 temp
= find_reg_note (p
, REG_EQUIV
, NULL_RTX
);
961 m
->set_src
= XEXP (temp
, 0), m
->move_insn
= 1;
964 temp
= find_reg_note (p
, REG_EQUAL
, NULL_RTX
);
965 if (temp
&& CONSTANT_P (XEXP (temp
, 0)))
966 m
->set_src
= XEXP (temp
, 0), m
->move_insn
= 1;
971 m
->is_equiv
= (find_reg_note (p
, REG_EQUIV
, NULL_RTX
) != 0);
974 /* If this register is always set within a STRICT_LOW_PART
975 or set to zero, then its high bytes are constant.
976 So clear them outside the loop and within the loop
977 just load the low bytes.
978 We must check that the machine has an instruction to do so.
979 Also, if the value loaded into the register
980 depends on the same register, this cannot be done. */
981 else if (SET_SRC (set
) == const0_rtx
982 && GET_CODE (NEXT_INSN (p
)) == INSN
983 && (set1
= single_set (NEXT_INSN (p
)))
984 && GET_CODE (set1
) == SET
985 && (GET_CODE (SET_DEST (set1
)) == STRICT_LOW_PART
)
986 && (GET_CODE (XEXP (SET_DEST (set1
), 0)) == SUBREG
)
987 && (SUBREG_REG (XEXP (SET_DEST (set1
), 0))
989 && !reg_mentioned_p (SET_DEST (set
), SET_SRC (set1
)))
991 int regno
= REGNO (SET_DEST (set
));
992 if (regs
->array
[regno
].set_in_loop
== 2)
995 m
= (struct movable
*) xmalloc (sizeof (struct movable
));
998 m
->set_dest
= SET_DEST (set
);
1005 m
->move_insn_first
= 0;
1007 /* If the insn may not be executed on some cycles,
1008 we can't clear the whole reg; clear just high part.
1009 Not even if the reg is used only within this loop.
1016 Clearing x before the inner loop could clobber a value
1017 being saved from the last time around the outer loop.
1018 However, if the reg is not used outside this loop
1019 and all uses of the register are in the same
1020 basic block as the store, there is no problem.
1022 If this insn was made by loop, we don't know its
1023 INSN_LUID and hence must make a conservative
1025 m
->global
= (INSN_UID (p
) >= max_uid_for_loop
1026 || LOOP_REG_GLOBAL_P (loop
, regno
)
1027 || (labels_in_range_p
1028 (p
, REGNO_FIRST_LUID (regno
))));
1029 if (maybe_never
&& m
->global
)
1030 m
->savemode
= GET_MODE (SET_SRC (set1
));
1032 m
->savemode
= VOIDmode
;
1036 m
->lifetime
= LOOP_REG_LIFETIME (loop
, regno
);
1038 for (i
= 0; i
< LOOP_REGNO_NREGS (regno
, SET_DEST (set
)); i
++)
1039 regs
->array
[regno
+i
].set_in_loop
= -1;
1040 /* Add M to the end of the chain MOVABLES. */
1041 loop_movables_add (movables
, m
);
1045 /* Past a call insn, we get to insns which might not be executed
1046 because the call might exit. This matters for insns that trap.
1047 Constant and pure call insns always return, so they don't count. */
1048 else if (GET_CODE (p
) == CALL_INSN
&& ! CONST_OR_PURE_CALL_P (p
))
1050 /* Past a label or a jump, we get to insns for which we
1051 can't count on whether or how many times they will be
1052 executed during each iteration. Therefore, we can
1053 only move out sets of trivial variables
1054 (those not used after the loop). */
1055 /* Similar code appears twice in strength_reduce. */
1056 else if ((GET_CODE (p
) == CODE_LABEL
|| GET_CODE (p
) == JUMP_INSN
)
1057 /* If we enter the loop in the middle, and scan around to the
1058 beginning, don't set maybe_never for that. This must be an
1059 unconditional jump, otherwise the code at the top of the
1060 loop might never be executed. Unconditional jumps are
1061 followed by a barrier then the loop_end. */
1062 && ! (GET_CODE (p
) == JUMP_INSN
&& JUMP_LABEL (p
) == loop
->top
1063 && NEXT_INSN (NEXT_INSN (p
)) == loop_end
1064 && any_uncondjump_p (p
)))
1066 else if (GET_CODE (p
) == NOTE
)
1068 /* At the virtual top of a converted loop, insns are again known to
1069 be executed: logically, the loop begins here even though the exit
1070 code has been duplicated. */
1071 if (NOTE_LINE_NUMBER (p
) == NOTE_INSN_LOOP_VTOP
&& loop_depth
== 0)
1072 maybe_never
= call_passed
= 0;
1073 else if (NOTE_LINE_NUMBER (p
) == NOTE_INSN_LOOP_BEG
)
1075 else if (NOTE_LINE_NUMBER (p
) == NOTE_INSN_LOOP_END
)
1080 /* If one movable subsumes another, ignore that other. */
1082 ignore_some_movables (movables
);
1084 /* For each movable insn, see if the reg that it loads
1085 leads when it dies right into another conditionally movable insn.
1086 If so, record that the second insn "forces" the first one,
1087 since the second can be moved only if the first is. */
1089 force_movables (movables
);
1091 /* See if there are multiple movable insns that load the same value.
1092 If there are, make all but the first point at the first one
1093 through the `match' field, and add the priorities of them
1094 all together as the priority of the first. */
1096 combine_movables (movables
, regs
);
1098 /* Now consider each movable insn to decide whether it is worth moving.
1099 Store 0 in regs->array[I].set_in_loop for each reg I that is moved.
1101 Generally this increases code size, so do not move moveables when
1102 optimizing for code size. */
1104 if (! optimize_size
)
1105 move_movables (loop
, movables
, threshold
, insn_count
);
1107 /* Now candidates that still are negative are those not moved.
1108 Change regs->array[I].set_in_loop to indicate that those are not actually
1110 for (i
= 0; i
< regs
->num
; i
++)
1111 if (regs
->array
[i
].set_in_loop
< 0)
1112 regs
->array
[i
].set_in_loop
= regs
->array
[i
].n_times_set
;
1114 /* Now that we've moved some things out of the loop, we might be able to
1115 hoist even more memory references. */
1118 /* Recalculate regs->array if load_mems has created new registers. */
1119 if (max_reg_num () > regs
->num
)
1120 loop_regs_scan (loop
, 0);
1122 for (update_start
= loop_start
;
1123 PREV_INSN (update_start
)
1124 && GET_CODE (PREV_INSN (update_start
)) != CODE_LABEL
;
1125 update_start
= PREV_INSN (update_start
))
1127 update_end
= NEXT_INSN (loop_end
);
1129 reg_scan_update (update_start
, update_end
, loop_max_reg
);
1130 loop_max_reg
= max_reg_num ();
1132 if (flag_strength_reduce
)
1134 if (update_end
&& GET_CODE (update_end
) == CODE_LABEL
)
1135 /* Ensure our label doesn't go away. */
1136 LABEL_NUSES (update_end
)++;
1138 strength_reduce (loop
, flags
);
1140 reg_scan_update (update_start
, update_end
, loop_max_reg
);
1141 loop_max_reg
= max_reg_num ();
1143 if (update_end
&& GET_CODE (update_end
) == CODE_LABEL
1144 && --LABEL_NUSES (update_end
) == 0)
1145 delete_related_insns (update_end
);
1149 /* The movable information is required for strength reduction. */
1150 loop_movables_free (movables
);
1157 /* Add elements to *OUTPUT to record all the pseudo-regs
1158 mentioned in IN_THIS but not mentioned in NOT_IN_THIS. */
1161 record_excess_regs (in_this
, not_in_this
, output
)
1162 rtx in_this
, not_in_this
;
1169 code
= GET_CODE (in_this
);
1183 if (REGNO (in_this
) >= FIRST_PSEUDO_REGISTER
1184 && ! reg_mentioned_p (in_this
, not_in_this
))
1185 *output
= gen_rtx_EXPR_LIST (VOIDmode
, in_this
, *output
);
1192 fmt
= GET_RTX_FORMAT (code
);
1193 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1200 for (j
= 0; j
< XVECLEN (in_this
, i
); j
++)
1201 record_excess_regs (XVECEXP (in_this
, i
, j
), not_in_this
, output
);
1205 record_excess_regs (XEXP (in_this
, i
), not_in_this
, output
);
1211 /* Check what regs are referred to in the libcall block ending with INSN,
1212 aside from those mentioned in the equivalent value.
1213 If there are none, return 0.
1214 If there are one or more, return an EXPR_LIST containing all of them. */
1217 libcall_other_reg (insn
, equiv
)
1220 rtx note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
1221 rtx p
= XEXP (note
, 0);
1224 /* First, find all the regs used in the libcall block
1225 that are not mentioned as inputs to the result. */
1229 if (GET_CODE (p
) == INSN
|| GET_CODE (p
) == JUMP_INSN
1230 || GET_CODE (p
) == CALL_INSN
)
1231 record_excess_regs (PATTERN (p
), equiv
, &output
);
1238 /* Return 1 if all uses of REG
1239 are between INSN and the end of the basic block. */
1242 reg_in_basic_block_p (insn
, reg
)
1245 int regno
= REGNO (reg
);
1248 if (REGNO_FIRST_UID (regno
) != INSN_UID (insn
))
1251 /* Search this basic block for the already recorded last use of the reg. */
1252 for (p
= insn
; p
; p
= NEXT_INSN (p
))
1254 switch (GET_CODE (p
))
1261 /* Ordinary insn: if this is the last use, we win. */
1262 if (REGNO_LAST_UID (regno
) == INSN_UID (p
))
1267 /* Jump insn: if this is the last use, we win. */
1268 if (REGNO_LAST_UID (regno
) == INSN_UID (p
))
1270 /* Otherwise, it's the end of the basic block, so we lose. */
1275 /* It's the end of the basic block, so we lose. */
1283 /* The "last use" that was recorded can't be found after the first
1284 use. This can happen when the last use was deleted while
1285 processing an inner loop, this inner loop was then completely
1286 unrolled, and the outer loop is always exited after the inner loop,
1287 so that everything after the first use becomes a single basic block. */
1291 /* Compute the benefit of eliminating the insns in the block whose
1292 last insn is LAST. This may be a group of insns used to compute a
1293 value directly or can contain a library call. */
1296 libcall_benefit (last
)
1302 for (insn
= XEXP (find_reg_note (last
, REG_RETVAL
, NULL_RTX
), 0);
1303 insn
!= last
; insn
= NEXT_INSN (insn
))
1305 if (GET_CODE (insn
) == CALL_INSN
)
1306 benefit
+= 10; /* Assume at least this many insns in a library
1308 else if (GET_CODE (insn
) == INSN
1309 && GET_CODE (PATTERN (insn
)) != USE
1310 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
1317 /* Skip COUNT insns from INSN, counting library calls as 1 insn. */
1320 skip_consec_insns (insn
, count
)
1324 for (; count
> 0; count
--)
1328 /* If first insn of libcall sequence, skip to end. */
1329 /* Do this at start of loop, since INSN is guaranteed to
1331 if (GET_CODE (insn
) != NOTE
1332 && (temp
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
)))
1333 insn
= XEXP (temp
, 0);
1336 insn
= NEXT_INSN (insn
);
1337 while (GET_CODE (insn
) == NOTE
);
1343 /* Ignore any movable whose insn falls within a libcall
1344 which is part of another movable.
1345 We make use of the fact that the movable for the libcall value
1346 was made later and so appears later on the chain. */
1349 ignore_some_movables (movables
)
1350 struct loop_movables
*movables
;
1352 struct movable
*m
, *m1
;
1354 for (m
= movables
->head
; m
; m
= m
->next
)
1356 /* Is this a movable for the value of a libcall? */
1357 rtx note
= find_reg_note (m
->insn
, REG_RETVAL
, NULL_RTX
);
1361 /* Check for earlier movables inside that range,
1362 and mark them invalid. We cannot use LUIDs here because
1363 insns created by loop.c for prior loops don't have LUIDs.
1364 Rather than reject all such insns from movables, we just
1365 explicitly check each insn in the libcall (since invariant
1366 libcalls aren't that common). */
1367 for (insn
= XEXP (note
, 0); insn
!= m
->insn
; insn
= NEXT_INSN (insn
))
1368 for (m1
= movables
->head
; m1
!= m
; m1
= m1
->next
)
1369 if (m1
->insn
== insn
)
1375 /* For each movable insn, see if the reg that it loads
1376 leads when it dies right into another conditionally movable insn.
1377 If so, record that the second insn "forces" the first one,
1378 since the second can be moved only if the first is. */
1381 force_movables (movables
)
1382 struct loop_movables
*movables
;
1384 struct movable
*m
, *m1
;
1386 for (m1
= movables
->head
; m1
; m1
= m1
->next
)
1387 /* Omit this if moving just the (SET (REG) 0) of a zero-extend. */
1388 if (!m1
->partial
&& !m1
->done
)
1390 int regno
= m1
->regno
;
1391 for (m
= m1
->next
; m
; m
= m
->next
)
1392 /* ??? Could this be a bug? What if CSE caused the
1393 register of M1 to be used after this insn?
1394 Since CSE does not update regno_last_uid,
1395 this insn M->insn might not be where it dies.
1396 But very likely this doesn't matter; what matters is
1397 that M's reg is computed from M1's reg. */
1398 if (INSN_UID (m
->insn
) == REGNO_LAST_UID (regno
)
1401 if (m
!= 0 && m
->set_src
== m1
->set_dest
1402 /* If m->consec, m->set_src isn't valid. */
1406 /* Increase the priority of the moving the first insn
1407 since it permits the second to be moved as well. */
1411 m1
->lifetime
+= m
->lifetime
;
1412 m1
->savings
+= m
->savings
;
1417 /* Find invariant expressions that are equal and can be combined into
1421 combine_movables (movables
, regs
)
1422 struct loop_movables
*movables
;
1423 struct loop_regs
*regs
;
1426 char *matched_regs
= (char *) xmalloc (regs
->num
);
1427 enum machine_mode mode
;
1429 /* Regs that are set more than once are not allowed to match
1430 or be matched. I'm no longer sure why not. */
1431 /* Perhaps testing m->consec_sets would be more appropriate here? */
1433 for (m
= movables
->head
; m
; m
= m
->next
)
1434 if (m
->match
== 0 && regs
->array
[m
->regno
].n_times_set
== 1
1438 int regno
= m
->regno
;
1440 memset (matched_regs
, 0, regs
->num
);
1441 matched_regs
[regno
] = 1;
1443 /* We want later insns to match the first one. Don't make the first
1444 one match any later ones. So start this loop at m->next. */
1445 for (m1
= m
->next
; m1
; m1
= m1
->next
)
1446 /* ??? HACK! move_movables does not verify that the replacement
1447 is valid, which can have disasterous effects with hard regs
1448 and match_dup. Turn combination off for now. */
1449 if (0 && m
!= m1
&& m1
->match
== 0
1450 && regs
->array
[m1
->regno
].n_times_set
== 1
1451 /* A reg used outside the loop mustn't be eliminated. */
1453 /* A reg used for zero-extending mustn't be eliminated. */
1455 && (matched_regs
[m1
->regno
]
1458 /* Can combine regs with different modes loaded from the
1459 same constant only if the modes are the same or
1460 if both are integer modes with M wider or the same
1461 width as M1. The check for integer is redundant, but
1462 safe, since the only case of differing destination
1463 modes with equal sources is when both sources are
1464 VOIDmode, i.e., CONST_INT. */
1465 (GET_MODE (m
->set_dest
) == GET_MODE (m1
->set_dest
)
1466 || (GET_MODE_CLASS (GET_MODE (m
->set_dest
)) == MODE_INT
1467 && GET_MODE_CLASS (GET_MODE (m1
->set_dest
)) == MODE_INT
1468 && (GET_MODE_BITSIZE (GET_MODE (m
->set_dest
))
1469 >= GET_MODE_BITSIZE (GET_MODE (m1
->set_dest
)))))
1470 /* See if the source of M1 says it matches M. */
1471 && ((GET_CODE (m1
->set_src
) == REG
1472 && matched_regs
[REGNO (m1
->set_src
)])
1473 || rtx_equal_for_loop_p (m
->set_src
, m1
->set_src
,
1475 && ((m
->dependencies
== m1
->dependencies
)
1476 || rtx_equal_p (m
->dependencies
, m1
->dependencies
)))
1478 m
->lifetime
+= m1
->lifetime
;
1479 m
->savings
+= m1
->savings
;
1482 matched_regs
[m1
->regno
] = 1;
1486 /* Now combine the regs used for zero-extension.
1487 This can be done for those not marked `global'
1488 provided their lives don't overlap. */
1490 for (mode
= GET_CLASS_NARROWEST_MODE (MODE_INT
); mode
!= VOIDmode
;
1491 mode
= GET_MODE_WIDER_MODE (mode
))
1493 struct movable
*m0
= 0;
1495 /* Combine all the registers for extension from mode MODE.
1496 Don't combine any that are used outside this loop. */
1497 for (m
= movables
->head
; m
; m
= m
->next
)
1498 if (m
->partial
&& ! m
->global
1499 && mode
== GET_MODE (SET_SRC (PATTERN (NEXT_INSN (m
->insn
)))))
1503 int first
= REGNO_FIRST_LUID (m
->regno
);
1504 int last
= REGNO_LAST_LUID (m
->regno
);
1508 /* First one: don't check for overlap, just record it. */
1513 /* Make sure they extend to the same mode.
1514 (Almost always true.) */
1515 if (GET_MODE (m
->set_dest
) != GET_MODE (m0
->set_dest
))
1518 /* We already have one: check for overlap with those
1519 already combined together. */
1520 for (m1
= movables
->head
; m1
!= m
; m1
= m1
->next
)
1521 if (m1
== m0
|| (m1
->partial
&& m1
->match
== m0
))
1522 if (! (REGNO_FIRST_LUID (m1
->regno
) > last
1523 || REGNO_LAST_LUID (m1
->regno
) < first
))
1526 /* No overlap: we can combine this with the others. */
1527 m0
->lifetime
+= m
->lifetime
;
1528 m0
->savings
+= m
->savings
;
1538 free (matched_regs
);
1541 /* Returns the number of movable instructions in LOOP that were not
1542 moved outside the loop. */
1545 num_unmoved_movables (loop
)
1546 const struct loop
*loop
;
1551 for (m
= LOOP_MOVABLES (loop
)->head
; m
; m
= m
->next
)
1559 /* Return 1 if regs X and Y will become the same if moved. */
1562 regs_match_p (x
, y
, movables
)
1564 struct loop_movables
*movables
;
1566 unsigned int xn
= REGNO (x
);
1567 unsigned int yn
= REGNO (y
);
1568 struct movable
*mx
, *my
;
1570 for (mx
= movables
->head
; mx
; mx
= mx
->next
)
1571 if (mx
->regno
== xn
)
1574 for (my
= movables
->head
; my
; my
= my
->next
)
1575 if (my
->regno
== yn
)
1579 && ((mx
->match
== my
->match
&& mx
->match
!= 0)
1581 || mx
== my
->match
));
1584 /* Return 1 if X and Y are identical-looking rtx's.
1585 This is the Lisp function EQUAL for rtx arguments.
1587 If two registers are matching movables or a movable register and an
1588 equivalent constant, consider them equal. */
1591 rtx_equal_for_loop_p (x
, y
, movables
, regs
)
1593 struct loop_movables
*movables
;
1594 struct loop_regs
*regs
;
1604 if (x
== 0 || y
== 0)
1607 code
= GET_CODE (x
);
1609 /* If we have a register and a constant, they may sometimes be
1611 if (GET_CODE (x
) == REG
&& regs
->array
[REGNO (x
)].set_in_loop
== -2
1614 for (m
= movables
->head
; m
; m
= m
->next
)
1615 if (m
->move_insn
&& m
->regno
== REGNO (x
)
1616 && rtx_equal_p (m
->set_src
, y
))
1619 else if (GET_CODE (y
) == REG
&& regs
->array
[REGNO (y
)].set_in_loop
== -2
1622 for (m
= movables
->head
; m
; m
= m
->next
)
1623 if (m
->move_insn
&& m
->regno
== REGNO (y
)
1624 && rtx_equal_p (m
->set_src
, x
))
1628 /* Otherwise, rtx's of different codes cannot be equal. */
1629 if (code
!= GET_CODE (y
))
1632 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1633 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1635 if (GET_MODE (x
) != GET_MODE (y
))
1638 /* These three types of rtx's can be compared nonrecursively. */
1640 return (REGNO (x
) == REGNO (y
) || regs_match_p (x
, y
, movables
));
1642 if (code
== LABEL_REF
)
1643 return XEXP (x
, 0) == XEXP (y
, 0);
1644 if (code
== SYMBOL_REF
)
1645 return XSTR (x
, 0) == XSTR (y
, 0);
1647 /* Compare the elements. If any pair of corresponding elements
1648 fail to match, return 0 for the whole things. */
1650 fmt
= GET_RTX_FORMAT (code
);
1651 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1656 if (XWINT (x
, i
) != XWINT (y
, i
))
1661 if (XINT (x
, i
) != XINT (y
, i
))
1666 /* Two vectors must have the same length. */
1667 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1670 /* And the corresponding elements must match. */
1671 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1672 if (rtx_equal_for_loop_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
),
1673 movables
, regs
) == 0)
1678 if (rtx_equal_for_loop_p (XEXP (x
, i
), XEXP (y
, i
), movables
, regs
)
1684 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1689 /* These are just backpointers, so they don't matter. */
1695 /* It is believed that rtx's at this level will never
1696 contain anything but integers and other rtx's,
1697 except for within LABEL_REFs and SYMBOL_REFs. */
1705 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to all
1706 insns in INSNS which use the reference. LABEL_NUSES for CODE_LABEL
1707 references is incremented once for each added note. */
1710 add_label_notes (x
, insns
)
1714 enum rtx_code code
= GET_CODE (x
);
1719 if (code
== LABEL_REF
&& !LABEL_REF_NONLOCAL_P (x
))
1721 /* This code used to ignore labels that referred to dispatch tables to
1722 avoid flow generating (slighly) worse code.
1724 We no longer ignore such label references (see LABEL_REF handling in
1725 mark_jump_label for additional information). */
1726 for (insn
= insns
; insn
; insn
= NEXT_INSN (insn
))
1727 if (reg_mentioned_p (XEXP (x
, 0), insn
))
1729 REG_NOTES (insn
) = gen_rtx_INSN_LIST (REG_LABEL
, XEXP (x
, 0),
1731 if (LABEL_P (XEXP (x
, 0)))
1732 LABEL_NUSES (XEXP (x
, 0))++;
1736 fmt
= GET_RTX_FORMAT (code
);
1737 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1740 add_label_notes (XEXP (x
, i
), insns
);
1741 else if (fmt
[i
] == 'E')
1742 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
1743 add_label_notes (XVECEXP (x
, i
, j
), insns
);
1747 /* Scan MOVABLES, and move the insns that deserve to be moved.
1748 If two matching movables are combined, replace one reg with the
1749 other throughout. */
1752 move_movables (loop
, movables
, threshold
, insn_count
)
1754 struct loop_movables
*movables
;
1758 struct loop_regs
*regs
= LOOP_REGS (loop
);
1759 int nregs
= regs
->num
;
1763 rtx loop_start
= loop
->start
;
1764 rtx loop_end
= loop
->end
;
1765 /* Map of pseudo-register replacements to handle combining
1766 when we move several insns that load the same value
1767 into different pseudo-registers. */
1768 rtx
*reg_map
= (rtx
*) xcalloc (nregs
, sizeof (rtx
));
1769 char *already_moved
= (char *) xcalloc (nregs
, sizeof (char));
1771 for (m
= movables
->head
; m
; m
= m
->next
)
1773 /* Describe this movable insn. */
1775 if (loop_dump_stream
)
1777 fprintf (loop_dump_stream
, "Insn %d: regno %d (life %d), ",
1778 INSN_UID (m
->insn
), m
->regno
, m
->lifetime
);
1780 fprintf (loop_dump_stream
, "consec %d, ", m
->consec
);
1782 fprintf (loop_dump_stream
, "cond ");
1784 fprintf (loop_dump_stream
, "force ");
1786 fprintf (loop_dump_stream
, "global ");
1788 fprintf (loop_dump_stream
, "done ");
1790 fprintf (loop_dump_stream
, "move-insn ");
1792 fprintf (loop_dump_stream
, "matches %d ",
1793 INSN_UID (m
->match
->insn
));
1795 fprintf (loop_dump_stream
, "forces %d ",
1796 INSN_UID (m
->forces
->insn
));
1799 /* Ignore the insn if it's already done (it matched something else).
1800 Otherwise, see if it is now safe to move. */
1804 || (1 == loop_invariant_p (loop
, m
->set_src
)
1805 && (m
->dependencies
== 0
1806 || 1 == loop_invariant_p (loop
, m
->dependencies
))
1808 || 1 == consec_sets_invariant_p (loop
, m
->set_dest
,
1811 && (! m
->forces
|| m
->forces
->done
))
1815 int savings
= m
->savings
;
1817 /* We have an insn that is safe to move.
1818 Compute its desirability. */
1823 if (loop_dump_stream
)
1824 fprintf (loop_dump_stream
, "savings %d ", savings
);
1826 if (regs
->array
[regno
].moved_once
&& loop_dump_stream
)
1827 fprintf (loop_dump_stream
, "halved since already moved ");
1829 /* An insn MUST be moved if we already moved something else
1830 which is safe only if this one is moved too: that is,
1831 if already_moved[REGNO] is nonzero. */
1833 /* An insn is desirable to move if the new lifetime of the
1834 register is no more than THRESHOLD times the old lifetime.
1835 If it's not desirable, it means the loop is so big
1836 that moving won't speed things up much,
1837 and it is liable to make register usage worse. */
1839 /* It is also desirable to move if it can be moved at no
1840 extra cost because something else was already moved. */
1842 if (already_moved
[regno
]
1843 || flag_move_all_movables
1844 || (threshold
* savings
* m
->lifetime
) >=
1845 (regs
->array
[regno
].moved_once
? insn_count
* 2 : insn_count
)
1846 || (m
->forces
&& m
->forces
->done
1847 && regs
->array
[m
->forces
->regno
].n_times_set
== 1))
1851 rtx first
= NULL_RTX
;
1853 /* Now move the insns that set the reg. */
1855 if (m
->partial
&& m
->match
)
1859 /* Find the end of this chain of matching regs.
1860 Thus, we load each reg in the chain from that one reg.
1861 And that reg is loaded with 0 directly,
1862 since it has ->match == 0. */
1863 for (m1
= m
; m1
->match
; m1
= m1
->match
);
1864 newpat
= gen_move_insn (SET_DEST (PATTERN (m
->insn
)),
1865 SET_DEST (PATTERN (m1
->insn
)));
1866 i1
= loop_insn_hoist (loop
, newpat
);
1868 /* Mark the moved, invariant reg as being allowed to
1869 share a hard reg with the other matching invariant. */
1870 REG_NOTES (i1
) = REG_NOTES (m
->insn
);
1871 r1
= SET_DEST (PATTERN (m
->insn
));
1872 r2
= SET_DEST (PATTERN (m1
->insn
));
1874 = gen_rtx_EXPR_LIST (VOIDmode
, r1
,
1875 gen_rtx_EXPR_LIST (VOIDmode
, r2
,
1877 delete_insn (m
->insn
);
1882 if (loop_dump_stream
)
1883 fprintf (loop_dump_stream
, " moved to %d", INSN_UID (i1
));
1885 /* If we are to re-generate the item being moved with a
1886 new move insn, first delete what we have and then emit
1887 the move insn before the loop. */
1888 else if (m
->move_insn
)
1892 for (count
= m
->consec
; count
>= 0; count
--)
1894 /* If this is the first insn of a library call sequence,
1896 if (GET_CODE (p
) != NOTE
1897 && (temp
= find_reg_note (p
, REG_LIBCALL
, NULL_RTX
)))
1900 /* If this is the last insn of a libcall sequence, then
1901 delete every insn in the sequence except the last.
1902 The last insn is handled in the normal manner. */
1903 if (GET_CODE (p
) != NOTE
1904 && (temp
= find_reg_note (p
, REG_RETVAL
, NULL_RTX
)))
1906 temp
= XEXP (temp
, 0);
1908 temp
= delete_insn (temp
);
1912 p
= delete_insn (p
);
1914 /* simplify_giv_expr expects that it can walk the insns
1915 at m->insn forwards and see this old sequence we are
1916 tossing here. delete_insn does preserve the next
1917 pointers, but when we skip over a NOTE we must fix
1918 it up. Otherwise that code walks into the non-deleted
1920 while (p
&& GET_CODE (p
) == NOTE
)
1921 p
= NEXT_INSN (temp
) = NEXT_INSN (p
);
1925 emit_move_insn (m
->set_dest
, m
->set_src
);
1926 temp
= get_insns ();
1927 seq
= gen_sequence ();
1930 add_label_notes (m
->set_src
, temp
);
1932 i1
= loop_insn_hoist (loop
, seq
);
1933 if (! find_reg_note (i1
, REG_EQUAL
, NULL_RTX
))
1934 set_unique_reg_note (i1
,
1935 m
->is_equiv
? REG_EQUIV
: REG_EQUAL
,
1938 if (loop_dump_stream
)
1939 fprintf (loop_dump_stream
, " moved to %d", INSN_UID (i1
));
1941 /* The more regs we move, the less we like moving them. */
1946 for (count
= m
->consec
; count
>= 0; count
--)
1950 /* If first insn of libcall sequence, skip to end. */
1951 /* Do this at start of loop, since p is guaranteed to
1953 if (GET_CODE (p
) != NOTE
1954 && (temp
= find_reg_note (p
, REG_LIBCALL
, NULL_RTX
)))
1957 /* If last insn of libcall sequence, move all
1958 insns except the last before the loop. The last
1959 insn is handled in the normal manner. */
1960 if (GET_CODE (p
) != NOTE
1961 && (temp
= find_reg_note (p
, REG_RETVAL
, NULL_RTX
)))
1965 rtx fn_address_insn
= 0;
1968 for (temp
= XEXP (temp
, 0); temp
!= p
;
1969 temp
= NEXT_INSN (temp
))
1975 if (GET_CODE (temp
) == NOTE
)
1978 body
= PATTERN (temp
);
1980 /* Find the next insn after TEMP,
1981 not counting USE or NOTE insns. */
1982 for (next
= NEXT_INSN (temp
); next
!= p
;
1983 next
= NEXT_INSN (next
))
1984 if (! (GET_CODE (next
) == INSN
1985 && GET_CODE (PATTERN (next
)) == USE
)
1986 && GET_CODE (next
) != NOTE
)
1989 /* If that is the call, this may be the insn
1990 that loads the function address.
1992 Extract the function address from the insn
1993 that loads it into a register.
1994 If this insn was cse'd, we get incorrect code.
1996 So emit a new move insn that copies the
1997 function address into the register that the
1998 call insn will use. flow.c will delete any
1999 redundant stores that we have created. */
2000 if (GET_CODE (next
) == CALL_INSN
2001 && GET_CODE (body
) == SET
2002 && GET_CODE (SET_DEST (body
)) == REG
2003 && (n
= find_reg_note (temp
, REG_EQUAL
,
2006 fn_reg
= SET_SRC (body
);
2007 if (GET_CODE (fn_reg
) != REG
)
2008 fn_reg
= SET_DEST (body
);
2009 fn_address
= XEXP (n
, 0);
2010 fn_address_insn
= temp
;
2012 /* We have the call insn.
2013 If it uses the register we suspect it might,
2014 load it with the correct address directly. */
2015 if (GET_CODE (temp
) == CALL_INSN
2017 && reg_referenced_p (fn_reg
, body
))
2018 loop_insn_emit_after (loop
, 0, fn_address_insn
,
2020 (fn_reg
, fn_address
));
2022 if (GET_CODE (temp
) == CALL_INSN
)
2024 i1
= loop_call_insn_hoist (loop
, body
);
2025 /* Because the USAGE information potentially
2026 contains objects other than hard registers
2027 we need to copy it. */
2028 if (CALL_INSN_FUNCTION_USAGE (temp
))
2029 CALL_INSN_FUNCTION_USAGE (i1
)
2030 = copy_rtx (CALL_INSN_FUNCTION_USAGE (temp
));
2033 i1
= loop_insn_hoist (loop
, body
);
2036 if (temp
== fn_address_insn
)
2037 fn_address_insn
= i1
;
2038 REG_NOTES (i1
) = REG_NOTES (temp
);
2039 REG_NOTES (temp
) = NULL
;
2045 if (m
->savemode
!= VOIDmode
)
2047 /* P sets REG to zero; but we should clear only
2048 the bits that are not covered by the mode
2050 rtx reg
= m
->set_dest
;
2055 tem
= expand_simple_binop
2056 (GET_MODE (reg
), AND
, reg
,
2057 GEN_INT ((((HOST_WIDE_INT
) 1
2058 << GET_MODE_BITSIZE (m
->savemode
)))
2060 reg
, 1, OPTAB_LIB_WIDEN
);
2064 emit_move_insn (reg
, tem
);
2065 sequence
= gen_sequence ();
2067 i1
= loop_insn_hoist (loop
, sequence
);
2069 else if (GET_CODE (p
) == CALL_INSN
)
2071 i1
= loop_call_insn_hoist (loop
, PATTERN (p
));
2072 /* Because the USAGE information potentially
2073 contains objects other than hard registers
2074 we need to copy it. */
2075 if (CALL_INSN_FUNCTION_USAGE (p
))
2076 CALL_INSN_FUNCTION_USAGE (i1
)
2077 = copy_rtx (CALL_INSN_FUNCTION_USAGE (p
));
2079 else if (count
== m
->consec
&& m
->move_insn_first
)
2082 /* The SET_SRC might not be invariant, so we must
2083 use the REG_EQUAL note. */
2085 emit_move_insn (m
->set_dest
, m
->set_src
);
2086 temp
= get_insns ();
2087 seq
= gen_sequence ();
2090 add_label_notes (m
->set_src
, temp
);
2092 i1
= loop_insn_hoist (loop
, seq
);
2093 if (! find_reg_note (i1
, REG_EQUAL
, NULL_RTX
))
2094 set_unique_reg_note (i1
, m
->is_equiv
? REG_EQUIV
2095 : REG_EQUAL
, m
->set_src
);
2098 i1
= loop_insn_hoist (loop
, PATTERN (p
));
2100 if (REG_NOTES (i1
) == 0)
2102 REG_NOTES (i1
) = REG_NOTES (p
);
2103 REG_NOTES (p
) = NULL
;
2105 /* If there is a REG_EQUAL note present whose value
2106 is not loop invariant, then delete it, since it
2107 may cause problems with later optimization passes.
2108 It is possible for cse to create such notes
2109 like this as a result of record_jump_cond. */
2111 if ((temp
= find_reg_note (i1
, REG_EQUAL
, NULL_RTX
))
2112 && ! loop_invariant_p (loop
, XEXP (temp
, 0)))
2113 remove_note (i1
, temp
);
2119 if (loop_dump_stream
)
2120 fprintf (loop_dump_stream
, " moved to %d",
2123 /* If library call, now fix the REG_NOTES that contain
2124 insn pointers, namely REG_LIBCALL on FIRST
2125 and REG_RETVAL on I1. */
2126 if ((temp
= find_reg_note (i1
, REG_RETVAL
, NULL_RTX
)))
2128 XEXP (temp
, 0) = first
;
2129 temp
= find_reg_note (first
, REG_LIBCALL
, NULL_RTX
);
2130 XEXP (temp
, 0) = i1
;
2137 /* simplify_giv_expr expects that it can walk the insns
2138 at m->insn forwards and see this old sequence we are
2139 tossing here. delete_insn does preserve the next
2140 pointers, but when we skip over a NOTE we must fix
2141 it up. Otherwise that code walks into the non-deleted
2143 while (p
&& GET_CODE (p
) == NOTE
)
2144 p
= NEXT_INSN (temp
) = NEXT_INSN (p
);
2147 /* The more regs we move, the less we like moving them. */
2151 /* Any other movable that loads the same register
2153 already_moved
[regno
] = 1;
2155 /* This reg has been moved out of one loop. */
2156 regs
->array
[regno
].moved_once
= 1;
2158 /* The reg set here is now invariant. */
2162 for (i
= 0; i
< LOOP_REGNO_NREGS (regno
, m
->set_dest
); i
++)
2163 regs
->array
[regno
+i
].set_in_loop
= 0;
2168 /* Change the length-of-life info for the register
2169 to say it lives at least the full length of this loop.
2170 This will help guide optimizations in outer loops. */
2172 if (REGNO_FIRST_LUID (regno
) > INSN_LUID (loop_start
))
2173 /* This is the old insn before all the moved insns.
2174 We can't use the moved insn because it is out of range
2175 in uid_luid. Only the old insns have luids. */
2176 REGNO_FIRST_UID (regno
) = INSN_UID (loop_start
);
2177 if (REGNO_LAST_LUID (regno
) < INSN_LUID (loop_end
))
2178 REGNO_LAST_UID (regno
) = INSN_UID (loop_end
);
2180 /* Combine with this moved insn any other matching movables. */
2183 for (m1
= movables
->head
; m1
; m1
= m1
->next
)
2188 /* Schedule the reg loaded by M1
2189 for replacement so that shares the reg of M.
2190 If the modes differ (only possible in restricted
2191 circumstances, make a SUBREG.
2193 Note this assumes that the target dependent files
2194 treat REG and SUBREG equally, including within
2195 GO_IF_LEGITIMATE_ADDRESS and in all the
2196 predicates since we never verify that replacing the
2197 original register with a SUBREG results in a
2198 recognizable insn. */
2199 if (GET_MODE (m
->set_dest
) == GET_MODE (m1
->set_dest
))
2200 reg_map
[m1
->regno
] = m
->set_dest
;
2203 = gen_lowpart_common (GET_MODE (m1
->set_dest
),
2206 /* Get rid of the matching insn
2207 and prevent further processing of it. */
2210 /* if library call, delete all insns. */
2211 if ((temp
= find_reg_note (m1
->insn
, REG_RETVAL
,
2213 delete_insn_chain (XEXP (temp
, 0), m1
->insn
);
2215 delete_insn (m1
->insn
);
2217 /* Any other movable that loads the same register
2219 already_moved
[m1
->regno
] = 1;
2221 /* The reg merged here is now invariant,
2222 if the reg it matches is invariant. */
2227 i
< LOOP_REGNO_NREGS (regno
, m1
->set_dest
);
2229 regs
->array
[m1
->regno
+i
].set_in_loop
= 0;
2233 else if (loop_dump_stream
)
2234 fprintf (loop_dump_stream
, "not desirable");
2236 else if (loop_dump_stream
&& !m
->match
)
2237 fprintf (loop_dump_stream
, "not safe");
2239 if (loop_dump_stream
)
2240 fprintf (loop_dump_stream
, "\n");
2244 new_start
= loop_start
;
2246 /* Go through all the instructions in the loop, making
2247 all the register substitutions scheduled in REG_MAP. */
2248 for (p
= new_start
; p
!= loop_end
; p
= NEXT_INSN (p
))
2249 if (GET_CODE (p
) == INSN
|| GET_CODE (p
) == JUMP_INSN
2250 || GET_CODE (p
) == CALL_INSN
)
2252 replace_regs (PATTERN (p
), reg_map
, nregs
, 0);
2253 replace_regs (REG_NOTES (p
), reg_map
, nregs
, 0);
2259 free (already_moved
);
2264 loop_movables_add (movables
, m
)
2265 struct loop_movables
*movables
;
2268 if (movables
->head
== 0)
2271 movables
->last
->next
= m
;
2277 loop_movables_free (movables
)
2278 struct loop_movables
*movables
;
2281 struct movable
*m_next
;
2283 for (m
= movables
->head
; m
; m
= m_next
)
2291 /* Scan X and replace the address of any MEM in it with ADDR.
2292 REG is the address that MEM should have before the replacement. */
2295 replace_call_address (x
, reg
, addr
)
2304 code
= GET_CODE (x
);
2318 /* Short cut for very common case. */
2319 replace_call_address (XEXP (x
, 1), reg
, addr
);
2323 /* Short cut for very common case. */
2324 replace_call_address (XEXP (x
, 0), reg
, addr
);
2328 /* If this MEM uses a reg other than the one we expected,
2329 something is wrong. */
2330 if (XEXP (x
, 0) != reg
)
2339 fmt
= GET_RTX_FORMAT (code
);
2340 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
2343 replace_call_address (XEXP (x
, i
), reg
, addr
);
2344 else if (fmt
[i
] == 'E')
2347 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2348 replace_call_address (XVECEXP (x
, i
, j
), reg
, addr
);
2354 /* Return the number of memory refs to addresses that vary
2358 count_nonfixed_reads (loop
, x
)
2359 const struct loop
*loop
;
2370 code
= GET_CODE (x
);
2384 return ((loop_invariant_p (loop
, XEXP (x
, 0)) != 1)
2385 + count_nonfixed_reads (loop
, XEXP (x
, 0)));
2392 fmt
= GET_RTX_FORMAT (code
);
2393 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
2396 value
+= count_nonfixed_reads (loop
, XEXP (x
, i
));
2400 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2401 value
+= count_nonfixed_reads (loop
, XVECEXP (x
, i
, j
));
2407 /* Scan a loop setting the elements `cont', `vtop', `loops_enclosed',
2408 `has_call', `has_nonconst_call', `has_volatile', `has_tablejump',
2409 `unknown_address_altered', `unknown_constant_address_altered', and
2410 `num_mem_sets' in LOOP. Also, fill in the array `mems' and the
2411 list `store_mems' in LOOP. */
2419 struct loop_info
*loop_info
= LOOP_INFO (loop
);
2420 rtx start
= loop
->start
;
2421 rtx end
= loop
->end
;
2422 /* The label after END. Jumping here is just like falling off the
2423 end of the loop. We use next_nonnote_insn instead of next_label
2424 as a hedge against the (pathological) case where some actual insn
2425 might end up between the two. */
2426 rtx exit_target
= next_nonnote_insn (end
);
2428 loop_info
->has_indirect_jump
= indirect_jump_in_function
;
2429 loop_info
->pre_header_has_call
= 0;
2430 loop_info
->has_call
= 0;
2431 loop_info
->has_nonconst_call
= 0;
2432 loop_info
->has_volatile
= 0;
2433 loop_info
->has_tablejump
= 0;
2434 loop_info
->has_multiple_exit_targets
= 0;
2437 loop_info
->unknown_address_altered
= 0;
2438 loop_info
->unknown_constant_address_altered
= 0;
2439 loop_info
->store_mems
= NULL_RTX
;
2440 loop_info
->first_loop_store_insn
= NULL_RTX
;
2441 loop_info
->mems_idx
= 0;
2442 loop_info
->num_mem_sets
= 0;
2445 for (insn
= start
; insn
&& GET_CODE (insn
) != CODE_LABEL
;
2446 insn
= PREV_INSN (insn
))
2448 if (GET_CODE (insn
) == CALL_INSN
)
2450 loop_info
->pre_header_has_call
= 1;
2455 for (insn
= NEXT_INSN (start
); insn
!= NEXT_INSN (end
);
2456 insn
= NEXT_INSN (insn
))
2458 switch (GET_CODE (insn
))
2461 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_BEG
)
2464 /* Count number of loops contained in this one. */
2467 else if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
)
2472 if (! CONST_OR_PURE_CALL_P (insn
))
2474 loop_info
->unknown_address_altered
= 1;
2475 loop_info
->has_nonconst_call
= 1;
2477 loop_info
->has_call
= 1;
2478 if (can_throw_internal (insn
))
2479 loop_info
->has_multiple_exit_targets
= 1;
2483 if (! loop_info
->has_multiple_exit_targets
)
2485 rtx set
= pc_set (insn
);
2491 if (GET_CODE (SET_SRC (set
)) == IF_THEN_ELSE
)
2493 label1
= XEXP (SET_SRC (set
), 1);
2494 label2
= XEXP (SET_SRC (set
), 2);
2498 label1
= SET_SRC (PATTERN (insn
));
2504 if (label1
&& label1
!= pc_rtx
)
2506 if (GET_CODE (label1
) != LABEL_REF
)
2508 /* Something tricky. */
2509 loop_info
->has_multiple_exit_targets
= 1;
2512 else if (XEXP (label1
, 0) != exit_target
2513 && LABEL_OUTSIDE_LOOP_P (label1
))
2515 /* A jump outside the current loop. */
2516 loop_info
->has_multiple_exit_targets
= 1;
2528 /* A return, or something tricky. */
2529 loop_info
->has_multiple_exit_targets
= 1;
2535 if (volatile_refs_p (PATTERN (insn
)))
2536 loop_info
->has_volatile
= 1;
2538 if (GET_CODE (insn
) == JUMP_INSN
2539 && (GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
2540 || GET_CODE (PATTERN (insn
)) == ADDR_VEC
))
2541 loop_info
->has_tablejump
= 1;
2543 note_stores (PATTERN (insn
), note_addr_stored
, loop_info
);
2544 if (! loop_info
->first_loop_store_insn
&& loop_info
->store_mems
)
2545 loop_info
->first_loop_store_insn
= insn
;
2547 if (flag_non_call_exceptions
&& can_throw_internal (insn
))
2548 loop_info
->has_multiple_exit_targets
= 1;
2556 /* Now, rescan the loop, setting up the LOOP_MEMS array. */
2557 if (/* An exception thrown by a called function might land us
2559 ! loop_info
->has_nonconst_call
2560 /* We don't want loads for MEMs moved to a location before the
2561 one at which their stack memory becomes allocated. (Note
2562 that this is not a problem for malloc, etc., since those
2563 require actual function calls. */
2564 && ! current_function_calls_alloca
2565 /* There are ways to leave the loop other than falling off the
2567 && ! loop_info
->has_multiple_exit_targets
)
2568 for (insn
= NEXT_INSN (start
); insn
!= NEXT_INSN (end
);
2569 insn
= NEXT_INSN (insn
))
2570 for_each_rtx (&insn
, insert_loop_mem
, loop_info
);
2572 /* BLKmode MEMs are added to LOOP_STORE_MEM as necessary so
2573 that loop_invariant_p and load_mems can use true_dependence
2574 to determine what is really clobbered. */
2575 if (loop_info
->unknown_address_altered
)
2577 rtx mem
= gen_rtx_MEM (BLKmode
, const0_rtx
);
2579 loop_info
->store_mems
2580 = gen_rtx_EXPR_LIST (VOIDmode
, mem
, loop_info
->store_mems
);
2582 if (loop_info
->unknown_constant_address_altered
)
2584 rtx mem
= gen_rtx_MEM (BLKmode
, const0_rtx
);
2586 RTX_UNCHANGING_P (mem
) = 1;
2587 loop_info
->store_mems
2588 = gen_rtx_EXPR_LIST (VOIDmode
, mem
, loop_info
->store_mems
);
2592 /* Scan the function looking for loops. Record the start and end of each loop.
2593 Also mark as invalid loops any loops that contain a setjmp or are branched
2594 to from outside the loop. */
2597 find_and_verify_loops (f
, loops
)
2599 struct loops
*loops
;
2604 struct loop
*current_loop
;
2605 struct loop
*next_loop
;
2608 num_loops
= loops
->num
;
2610 compute_luids (f
, NULL_RTX
, 0);
2612 /* If there are jumps to undefined labels,
2613 treat them as jumps out of any/all loops.
2614 This also avoids writing past end of tables when there are no loops. */
2617 /* Find boundaries of loops, mark which loops are contained within
2618 loops, and invalidate loops that have setjmp. */
2621 current_loop
= NULL
;
2622 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
2624 if (GET_CODE (insn
) == NOTE
)
2625 switch (NOTE_LINE_NUMBER (insn
))
2627 case NOTE_INSN_LOOP_BEG
:
2628 next_loop
= loops
->array
+ num_loops
;
2629 next_loop
->num
= num_loops
;
2631 next_loop
->start
= insn
;
2632 next_loop
->outer
= current_loop
;
2633 current_loop
= next_loop
;
2636 case NOTE_INSN_LOOP_CONT
:
2637 current_loop
->cont
= insn
;
2640 case NOTE_INSN_LOOP_VTOP
:
2641 current_loop
->vtop
= insn
;
2644 case NOTE_INSN_LOOP_END
:
2648 current_loop
->end
= insn
;
2649 current_loop
= current_loop
->outer
;
2656 if (GET_CODE (insn
) == CALL_INSN
2657 && find_reg_note (insn
, REG_SETJMP
, NULL
))
2659 /* In this case, we must invalidate our current loop and any
2661 for (loop
= current_loop
; loop
; loop
= loop
->outer
)
2664 if (loop_dump_stream
)
2665 fprintf (loop_dump_stream
,
2666 "\nLoop at %d ignored due to setjmp.\n",
2667 INSN_UID (loop
->start
));
2671 /* Note that this will mark the NOTE_INSN_LOOP_END note as being in the
2672 enclosing loop, but this doesn't matter. */
2673 uid_loop
[INSN_UID (insn
)] = current_loop
;
2676 /* Any loop containing a label used in an initializer must be invalidated,
2677 because it can be jumped into from anywhere. */
2679 for (label
= forced_labels
; label
; label
= XEXP (label
, 1))
2681 for (loop
= uid_loop
[INSN_UID (XEXP (label
, 0))];
2682 loop
; loop
= loop
->outer
)
2686 /* Any loop containing a label used for an exception handler must be
2687 invalidated, because it can be jumped into from anywhere. */
2689 for (label
= exception_handler_labels
; label
; label
= XEXP (label
, 1))
2691 for (loop
= uid_loop
[INSN_UID (XEXP (label
, 0))];
2692 loop
; loop
= loop
->outer
)
2696 /* Now scan all insn's in the function. If any JUMP_INSN branches into a
2697 loop that it is not contained within, that loop is marked invalid.
2698 If any INSN or CALL_INSN uses a label's address, then the loop containing
2699 that label is marked invalid, because it could be jumped into from
2702 Also look for blocks of code ending in an unconditional branch that
2703 exits the loop. If such a block is surrounded by a conditional
2704 branch around the block, move the block elsewhere (see below) and
2705 invert the jump to point to the code block. This may eliminate a
2706 label in our loop and will simplify processing by both us and a
2707 possible second cse pass. */
2709 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
2712 struct loop
*this_loop
= uid_loop
[INSN_UID (insn
)];
2714 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == CALL_INSN
)
2716 rtx note
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
);
2719 for (loop
= uid_loop
[INSN_UID (XEXP (note
, 0))];
2720 loop
; loop
= loop
->outer
)
2725 if (GET_CODE (insn
) != JUMP_INSN
)
2728 mark_loop_jump (PATTERN (insn
), this_loop
);
2730 /* See if this is an unconditional branch outside the loop. */
2732 && (GET_CODE (PATTERN (insn
)) == RETURN
2733 || (any_uncondjump_p (insn
)
2734 && onlyjump_p (insn
)
2735 && (uid_loop
[INSN_UID (JUMP_LABEL (insn
))]
2737 && get_max_uid () < max_uid_for_loop
)
2740 rtx our_next
= next_real_insn (insn
);
2741 rtx last_insn_to_move
= NEXT_INSN (insn
);
2742 struct loop
*dest_loop
;
2743 struct loop
*outer_loop
= NULL
;
2745 /* Go backwards until we reach the start of the loop, a label,
2747 for (p
= PREV_INSN (insn
);
2748 GET_CODE (p
) != CODE_LABEL
2749 && ! (GET_CODE (p
) == NOTE
2750 && NOTE_LINE_NUMBER (p
) == NOTE_INSN_LOOP_BEG
)
2751 && GET_CODE (p
) != JUMP_INSN
;
2755 /* Check for the case where we have a jump to an inner nested
2756 loop, and do not perform the optimization in that case. */
2758 if (JUMP_LABEL (insn
))
2760 dest_loop
= uid_loop
[INSN_UID (JUMP_LABEL (insn
))];
2763 for (outer_loop
= dest_loop
; outer_loop
;
2764 outer_loop
= outer_loop
->outer
)
2765 if (outer_loop
== this_loop
)
2770 /* Make sure that the target of P is within the current loop. */
2772 if (GET_CODE (p
) == JUMP_INSN
&& JUMP_LABEL (p
)
2773 && uid_loop
[INSN_UID (JUMP_LABEL (p
))] != this_loop
)
2774 outer_loop
= this_loop
;
2776 /* If we stopped on a JUMP_INSN to the next insn after INSN,
2777 we have a block of code to try to move.
2779 We look backward and then forward from the target of INSN
2780 to find a BARRIER at the same loop depth as the target.
2781 If we find such a BARRIER, we make a new label for the start
2782 of the block, invert the jump in P and point it to that label,
2783 and move the block of code to the spot we found. */
2786 && GET_CODE (p
) == JUMP_INSN
2787 && JUMP_LABEL (p
) != 0
2788 /* Just ignore jumps to labels that were never emitted.
2789 These always indicate compilation errors. */
2790 && INSN_UID (JUMP_LABEL (p
)) != 0
2791 && any_condjump_p (p
) && onlyjump_p (p
)
2792 && next_real_insn (JUMP_LABEL (p
)) == our_next
2793 /* If it's not safe to move the sequence, then we
2795 && insns_safe_to_move_p (p
, NEXT_INSN (insn
),
2796 &last_insn_to_move
))
2799 = JUMP_LABEL (insn
) ? JUMP_LABEL (insn
) : get_last_insn ();
2800 struct loop
*target_loop
= uid_loop
[INSN_UID (target
)];
2804 /* Search for possible garbage past the conditional jumps
2805 and look for the last barrier. */
2806 for (tmp
= last_insn_to_move
;
2807 tmp
&& GET_CODE (tmp
) != CODE_LABEL
; tmp
= NEXT_INSN (tmp
))
2808 if (GET_CODE (tmp
) == BARRIER
)
2809 last_insn_to_move
= tmp
;
2811 for (loc
= target
; loc
; loc
= PREV_INSN (loc
))
2812 if (GET_CODE (loc
) == BARRIER
2813 /* Don't move things inside a tablejump. */
2814 && ((loc2
= next_nonnote_insn (loc
)) == 0
2815 || GET_CODE (loc2
) != CODE_LABEL
2816 || (loc2
= next_nonnote_insn (loc2
)) == 0
2817 || GET_CODE (loc2
) != JUMP_INSN
2818 || (GET_CODE (PATTERN (loc2
)) != ADDR_VEC
2819 && GET_CODE (PATTERN (loc2
)) != ADDR_DIFF_VEC
))
2820 && uid_loop
[INSN_UID (loc
)] == target_loop
)
2824 for (loc
= target
; loc
; loc
= NEXT_INSN (loc
))
2825 if (GET_CODE (loc
) == BARRIER
2826 /* Don't move things inside a tablejump. */
2827 && ((loc2
= next_nonnote_insn (loc
)) == 0
2828 || GET_CODE (loc2
) != CODE_LABEL
2829 || (loc2
= next_nonnote_insn (loc2
)) == 0
2830 || GET_CODE (loc2
) != JUMP_INSN
2831 || (GET_CODE (PATTERN (loc2
)) != ADDR_VEC
2832 && GET_CODE (PATTERN (loc2
)) != ADDR_DIFF_VEC
))
2833 && uid_loop
[INSN_UID (loc
)] == target_loop
)
2838 rtx cond_label
= JUMP_LABEL (p
);
2839 rtx new_label
= get_label_after (p
);
2841 /* Ensure our label doesn't go away. */
2842 LABEL_NUSES (cond_label
)++;
2844 /* Verify that uid_loop is large enough and that
2846 if (invert_jump (p
, new_label
, 1))
2850 /* If no suitable BARRIER was found, create a suitable
2851 one before TARGET. Since TARGET is a fall through
2852 path, we'll need to insert an jump around our block
2853 and add a BARRIER before TARGET.
2855 This creates an extra unconditional jump outside
2856 the loop. However, the benefits of removing rarely
2857 executed instructions from inside the loop usually
2858 outweighs the cost of the extra unconditional jump
2859 outside the loop. */
2864 temp
= gen_jump (JUMP_LABEL (insn
));
2865 temp
= emit_jump_insn_before (temp
, target
);
2866 JUMP_LABEL (temp
) = JUMP_LABEL (insn
);
2867 LABEL_NUSES (JUMP_LABEL (insn
))++;
2868 loc
= emit_barrier_before (target
);
2871 /* Include the BARRIER after INSN and copy the
2873 if (squeeze_notes (&new_label
, &last_insn_to_move
))
2875 reorder_insns (new_label
, last_insn_to_move
, loc
);
2877 /* All those insns are now in TARGET_LOOP. */
2879 q
!= NEXT_INSN (last_insn_to_move
);
2881 uid_loop
[INSN_UID (q
)] = target_loop
;
2883 /* The label jumped to by INSN is no longer a loop
2884 exit. Unless INSN does not have a label (e.g.,
2885 it is a RETURN insn), search loop->exit_labels
2886 to find its label_ref, and remove it. Also turn
2887 off LABEL_OUTSIDE_LOOP_P bit. */
2888 if (JUMP_LABEL (insn
))
2890 for (q
= 0, r
= this_loop
->exit_labels
;
2892 q
= r
, r
= LABEL_NEXTREF (r
))
2893 if (XEXP (r
, 0) == JUMP_LABEL (insn
))
2895 LABEL_OUTSIDE_LOOP_P (r
) = 0;
2897 LABEL_NEXTREF (q
) = LABEL_NEXTREF (r
);
2899 this_loop
->exit_labels
= LABEL_NEXTREF (r
);
2903 for (loop
= this_loop
; loop
&& loop
!= target_loop
;
2907 /* If we didn't find it, then something is
2913 /* P is now a jump outside the loop, so it must be put
2914 in loop->exit_labels, and marked as such.
2915 The easiest way to do this is to just call
2916 mark_loop_jump again for P. */
2917 mark_loop_jump (PATTERN (p
), this_loop
);
2919 /* If INSN now jumps to the insn after it,
2921 if (JUMP_LABEL (insn
) != 0
2922 && (next_real_insn (JUMP_LABEL (insn
))
2923 == next_real_insn (insn
)))
2924 delete_related_insns (insn
);
2927 /* Continue the loop after where the conditional
2928 branch used to jump, since the only branch insn
2929 in the block (if it still remains) is an inter-loop
2930 branch and hence needs no processing. */
2931 insn
= NEXT_INSN (cond_label
);
2933 if (--LABEL_NUSES (cond_label
) == 0)
2934 delete_related_insns (cond_label
);
2936 /* This loop will be continued with NEXT_INSN (insn). */
2937 insn
= PREV_INSN (insn
);
2944 /* If any label in X jumps to a loop different from LOOP_NUM and any of the
2945 loops it is contained in, mark the target loop invalid.
2947 For speed, we assume that X is part of a pattern of a JUMP_INSN. */
2950 mark_loop_jump (x
, loop
)
2954 struct loop
*dest_loop
;
2955 struct loop
*outer_loop
;
2958 switch (GET_CODE (x
))
2971 /* There could be a label reference in here. */
2972 mark_loop_jump (XEXP (x
, 0), loop
);
2978 mark_loop_jump (XEXP (x
, 0), loop
);
2979 mark_loop_jump (XEXP (x
, 1), loop
);
2983 /* This may refer to a LABEL_REF or SYMBOL_REF. */
2984 mark_loop_jump (XEXP (x
, 1), loop
);
2989 mark_loop_jump (XEXP (x
, 0), loop
);
2993 dest_loop
= uid_loop
[INSN_UID (XEXP (x
, 0))];
2995 /* Link together all labels that branch outside the loop. This
2996 is used by final_[bg]iv_value and the loop unrolling code. Also
2997 mark this LABEL_REF so we know that this branch should predict
3000 /* A check to make sure the label is not in an inner nested loop,
3001 since this does not count as a loop exit. */
3004 for (outer_loop
= dest_loop
; outer_loop
;
3005 outer_loop
= outer_loop
->outer
)
3006 if (outer_loop
== loop
)
3012 if (loop
&& ! outer_loop
)
3014 LABEL_OUTSIDE_LOOP_P (x
) = 1;
3015 LABEL_NEXTREF (x
) = loop
->exit_labels
;
3016 loop
->exit_labels
= x
;
3018 for (outer_loop
= loop
;
3019 outer_loop
&& outer_loop
!= dest_loop
;
3020 outer_loop
= outer_loop
->outer
)
3021 outer_loop
->exit_count
++;
3024 /* If this is inside a loop, but not in the current loop or one enclosed
3025 by it, it invalidates at least one loop. */
3030 /* We must invalidate every nested loop containing the target of this
3031 label, except those that also contain the jump insn. */
3033 for (; dest_loop
; dest_loop
= dest_loop
->outer
)
3035 /* Stop when we reach a loop that also contains the jump insn. */
3036 for (outer_loop
= loop
; outer_loop
; outer_loop
= outer_loop
->outer
)
3037 if (dest_loop
== outer_loop
)
3040 /* If we get here, we know we need to invalidate a loop. */
3041 if (loop_dump_stream
&& ! dest_loop
->invalid
)
3042 fprintf (loop_dump_stream
,
3043 "\nLoop at %d ignored due to multiple entry points.\n",
3044 INSN_UID (dest_loop
->start
));
3046 dest_loop
->invalid
= 1;
3051 /* If this is not setting pc, ignore. */
3052 if (SET_DEST (x
) == pc_rtx
)
3053 mark_loop_jump (SET_SRC (x
), loop
);
3057 mark_loop_jump (XEXP (x
, 1), loop
);
3058 mark_loop_jump (XEXP (x
, 2), loop
);
3063 for (i
= 0; i
< XVECLEN (x
, 0); i
++)
3064 mark_loop_jump (XVECEXP (x
, 0, i
), loop
);
3068 for (i
= 0; i
< XVECLEN (x
, 1); i
++)
3069 mark_loop_jump (XVECEXP (x
, 1, i
), loop
);
3073 /* Strictly speaking this is not a jump into the loop, only a possible
3074 jump out of the loop. However, we have no way to link the destination
3075 of this jump onto the list of exit labels. To be safe we mark this
3076 loop and any containing loops as invalid. */
3079 for (outer_loop
= loop
; outer_loop
; outer_loop
= outer_loop
->outer
)
3081 if (loop_dump_stream
&& ! outer_loop
->invalid
)
3082 fprintf (loop_dump_stream
,
3083 "\nLoop at %d ignored due to unknown exit jump.\n",
3084 INSN_UID (outer_loop
->start
));
3085 outer_loop
->invalid
= 1;
3092 /* Return nonzero if there is a label in the range from
3093 insn INSN to and including the insn whose luid is END
3094 INSN must have an assigned luid (i.e., it must not have
3095 been previously created by loop.c). */
3098 labels_in_range_p (insn
, end
)
3102 while (insn
&& INSN_LUID (insn
) <= end
)
3104 if (GET_CODE (insn
) == CODE_LABEL
)
3106 insn
= NEXT_INSN (insn
);
3112 /* Record that a memory reference X is being set. */
3115 note_addr_stored (x
, y
, data
)
3117 rtx y ATTRIBUTE_UNUSED
;
3118 void *data ATTRIBUTE_UNUSED
;
3120 struct loop_info
*loop_info
= data
;
3122 if (x
== 0 || GET_CODE (x
) != MEM
)
3125 /* Count number of memory writes.
3126 This affects heuristics in strength_reduce. */
3127 loop_info
->num_mem_sets
++;
3129 /* BLKmode MEM means all memory is clobbered. */
3130 if (GET_MODE (x
) == BLKmode
)
3132 if (RTX_UNCHANGING_P (x
))
3133 loop_info
->unknown_constant_address_altered
= 1;
3135 loop_info
->unknown_address_altered
= 1;
3140 loop_info
->store_mems
= gen_rtx_EXPR_LIST (VOIDmode
, x
,
3141 loop_info
->store_mems
);
3144 /* X is a value modified by an INSN that references a biv inside a loop
3145 exit test (ie, X is somehow related to the value of the biv). If X
3146 is a pseudo that is used more than once, then the biv is (effectively)
3147 used more than once. DATA is a pointer to a loop_regs structure. */
3150 note_set_pseudo_multiple_uses (x
, y
, data
)
3152 rtx y ATTRIBUTE_UNUSED
;
3155 struct loop_regs
*regs
= (struct loop_regs
*) data
;
3160 while (GET_CODE (x
) == STRICT_LOW_PART
3161 || GET_CODE (x
) == SIGN_EXTRACT
3162 || GET_CODE (x
) == ZERO_EXTRACT
3163 || GET_CODE (x
) == SUBREG
)
3166 if (GET_CODE (x
) != REG
|| REGNO (x
) < FIRST_PSEUDO_REGISTER
)
3169 /* If we do not have usage information, or if we know the register
3170 is used more than once, note that fact for check_dbra_loop. */
3171 if (REGNO (x
) >= max_reg_before_loop
3172 || ! regs
->array
[REGNO (x
)].single_usage
3173 || regs
->array
[REGNO (x
)].single_usage
== const0_rtx
)
3174 regs
->multiple_uses
= 1;
3177 /* Return nonzero if the rtx X is invariant over the current loop.
3179 The value is 2 if we refer to something only conditionally invariant.
3181 A memory ref is invariant if it is not volatile and does not conflict
3182 with anything stored in `loop_info->store_mems'. */
3185 loop_invariant_p (loop
, x
)
3186 const struct loop
*loop
;
3189 struct loop_info
*loop_info
= LOOP_INFO (loop
);
3190 struct loop_regs
*regs
= LOOP_REGS (loop
);
3194 int conditional
= 0;
3199 code
= GET_CODE (x
);
3209 /* A LABEL_REF is normally invariant, however, if we are unrolling
3210 loops, and this label is inside the loop, then it isn't invariant.
3211 This is because each unrolled copy of the loop body will have
3212 a copy of this label. If this was invariant, then an insn loading
3213 the address of this label into a register might get moved outside
3214 the loop, and then each loop body would end up using the same label.
3216 We don't know the loop bounds here though, so just fail for all
3218 if (flag_unroll_loops
)
3225 case UNSPEC_VOLATILE
:
3229 /* We used to check RTX_UNCHANGING_P (x) here, but that is invalid
3230 since the reg might be set by initialization within the loop. */
3232 if ((x
== frame_pointer_rtx
|| x
== hard_frame_pointer_rtx
3233 || x
== arg_pointer_rtx
|| x
== pic_offset_table_rtx
)
3234 && ! current_function_has_nonlocal_goto
)
3237 if (LOOP_INFO (loop
)->has_call
3238 && REGNO (x
) < FIRST_PSEUDO_REGISTER
&& call_used_regs
[REGNO (x
)])
3241 if (regs
->array
[REGNO (x
)].set_in_loop
< 0)
3244 return regs
->array
[REGNO (x
)].set_in_loop
== 0;
3247 /* Volatile memory references must be rejected. Do this before
3248 checking for read-only items, so that volatile read-only items
3249 will be rejected also. */
3250 if (MEM_VOLATILE_P (x
))
3253 /* See if there is any dependence between a store and this load. */
3254 mem_list_entry
= loop_info
->store_mems
;
3255 while (mem_list_entry
)
3257 if (true_dependence (XEXP (mem_list_entry
, 0), VOIDmode
,
3261 mem_list_entry
= XEXP (mem_list_entry
, 1);
3264 /* It's not invalidated by a store in memory
3265 but we must still verify the address is invariant. */
3269 /* Don't mess with insns declared volatile. */
3270 if (MEM_VOLATILE_P (x
))
3278 fmt
= GET_RTX_FORMAT (code
);
3279 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3283 int tem
= loop_invariant_p (loop
, XEXP (x
, i
));
3289 else if (fmt
[i
] == 'E')
3292 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3294 int tem
= loop_invariant_p (loop
, XVECEXP (x
, i
, j
));
3304 return 1 + conditional
;
3307 /* Return nonzero if all the insns in the loop that set REG
3308 are INSN and the immediately following insns,
3309 and if each of those insns sets REG in an invariant way
3310 (not counting uses of REG in them).
3312 The value is 2 if some of these insns are only conditionally invariant.
3314 We assume that INSN itself is the first set of REG
3315 and that its source is invariant. */
3318 consec_sets_invariant_p (loop
, reg
, n_sets
, insn
)
3319 const struct loop
*loop
;
3323 struct loop_regs
*regs
= LOOP_REGS (loop
);
3325 unsigned int regno
= REGNO (reg
);
3327 /* Number of sets we have to insist on finding after INSN. */
3328 int count
= n_sets
- 1;
3329 int old
= regs
->array
[regno
].set_in_loop
;
3333 /* If N_SETS hit the limit, we can't rely on its value. */
3337 regs
->array
[regno
].set_in_loop
= 0;
3345 code
= GET_CODE (p
);
3347 /* If library call, skip to end of it. */
3348 if (code
== INSN
&& (temp
= find_reg_note (p
, REG_LIBCALL
, NULL_RTX
)))
3353 && (set
= single_set (p
))
3354 && GET_CODE (SET_DEST (set
)) == REG
3355 && REGNO (SET_DEST (set
)) == regno
)
3357 this = loop_invariant_p (loop
, SET_SRC (set
));
3360 else if ((temp
= find_reg_note (p
, REG_EQUAL
, NULL_RTX
)))
3362 /* If this is a libcall, then any invariant REG_EQUAL note is OK.
3363 If this is an ordinary insn, then only CONSTANT_P REG_EQUAL
3365 this = (CONSTANT_P (XEXP (temp
, 0))
3366 || (find_reg_note (p
, REG_RETVAL
, NULL_RTX
)
3367 && loop_invariant_p (loop
, XEXP (temp
, 0))));
3374 else if (code
!= NOTE
)
3376 regs
->array
[regno
].set_in_loop
= old
;
3381 regs
->array
[regno
].set_in_loop
= old
;
3382 /* If loop_invariant_p ever returned 2, we return 2. */
3383 return 1 + (value
& 2);
3387 /* I don't think this condition is sufficient to allow INSN
3388 to be moved, so we no longer test it. */
3390 /* Return 1 if all insns in the basic block of INSN and following INSN
3391 that set REG are invariant according to TABLE. */
3394 all_sets_invariant_p (reg
, insn
, table
)
3399 int regno
= REGNO (reg
);
3405 code
= GET_CODE (p
);
3406 if (code
== CODE_LABEL
|| code
== JUMP_INSN
)
3408 if (code
== INSN
&& GET_CODE (PATTERN (p
)) == SET
3409 && GET_CODE (SET_DEST (PATTERN (p
))) == REG
3410 && REGNO (SET_DEST (PATTERN (p
))) == regno
)
3412 if (! loop_invariant_p (loop
, SET_SRC (PATTERN (p
)), table
))
3419 /* Look at all uses (not sets) of registers in X. For each, if it is
3420 the single use, set USAGE[REGNO] to INSN; if there was a previous use in
3421 a different insn, set USAGE[REGNO] to const0_rtx. */
3424 find_single_use_in_loop (regs
, insn
, x
)
3425 struct loop_regs
*regs
;
3429 enum rtx_code code
= GET_CODE (x
);
3430 const char *fmt
= GET_RTX_FORMAT (code
);
3434 regs
->array
[REGNO (x
)].single_usage
3435 = (regs
->array
[REGNO (x
)].single_usage
!= 0
3436 && regs
->array
[REGNO (x
)].single_usage
!= insn
)
3437 ? const0_rtx
: insn
;
3439 else if (code
== SET
)
3441 /* Don't count SET_DEST if it is a REG; otherwise count things
3442 in SET_DEST because if a register is partially modified, it won't
3443 show up as a potential movable so we don't care how USAGE is set
3445 if (GET_CODE (SET_DEST (x
)) != REG
)
3446 find_single_use_in_loop (regs
, insn
, SET_DEST (x
));
3447 find_single_use_in_loop (regs
, insn
, SET_SRC (x
));
3450 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3452 if (fmt
[i
] == 'e' && XEXP (x
, i
) != 0)
3453 find_single_use_in_loop (regs
, insn
, XEXP (x
, i
));
3454 else if (fmt
[i
] == 'E')
3455 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
3456 find_single_use_in_loop (regs
, insn
, XVECEXP (x
, i
, j
));
3460 /* Count and record any set in X which is contained in INSN. Update
3461 REGS->array[I].MAY_NOT_OPTIMIZE and LAST_SET for any register I set
3465 count_one_set (regs
, insn
, x
, last_set
)
3466 struct loop_regs
*regs
;
3470 if (GET_CODE (x
) == CLOBBER
&& GET_CODE (XEXP (x
, 0)) == REG
)
3471 /* Don't move a reg that has an explicit clobber.
3472 It's not worth the pain to try to do it correctly. */
3473 regs
->array
[REGNO (XEXP (x
, 0))].may_not_optimize
= 1;
3475 if (GET_CODE (x
) == SET
|| GET_CODE (x
) == CLOBBER
)
3477 rtx dest
= SET_DEST (x
);
3478 while (GET_CODE (dest
) == SUBREG
3479 || GET_CODE (dest
) == ZERO_EXTRACT
3480 || GET_CODE (dest
) == SIGN_EXTRACT
3481 || GET_CODE (dest
) == STRICT_LOW_PART
)
3482 dest
= XEXP (dest
, 0);
3483 if (GET_CODE (dest
) == REG
)
3486 int regno
= REGNO (dest
);
3487 for (i
= 0; i
< LOOP_REGNO_NREGS (regno
, dest
); i
++)
3489 /* If this is the first setting of this reg
3490 in current basic block, and it was set before,
3491 it must be set in two basic blocks, so it cannot
3492 be moved out of the loop. */
3493 if (regs
->array
[regno
].set_in_loop
> 0
3495 regs
->array
[regno
+i
].may_not_optimize
= 1;
3496 /* If this is not first setting in current basic block,
3497 see if reg was used in between previous one and this.
3498 If so, neither one can be moved. */
3499 if (last_set
[regno
] != 0
3500 && reg_used_between_p (dest
, last_set
[regno
], insn
))
3501 regs
->array
[regno
+i
].may_not_optimize
= 1;
3502 if (regs
->array
[regno
+i
].set_in_loop
< 127)
3503 ++regs
->array
[regno
+i
].set_in_loop
;
3504 last_set
[regno
+i
] = insn
;
3510 /* Given a loop that is bounded by LOOP->START and LOOP->END and that
3511 is entered at LOOP->SCAN_START, return 1 if the register set in SET
3512 contained in insn INSN is used by any insn that precedes INSN in
3513 cyclic order starting from the loop entry point.
3515 We don't want to use INSN_LUID here because if we restrict INSN to those
3516 that have a valid INSN_LUID, it means we cannot move an invariant out
3517 from an inner loop past two loops. */
3520 loop_reg_used_before_p (loop
, set
, insn
)
3521 const struct loop
*loop
;
3524 rtx reg
= SET_DEST (set
);
3527 /* Scan forward checking for register usage. If we hit INSN, we
3528 are done. Otherwise, if we hit LOOP->END, wrap around to LOOP->START. */
3529 for (p
= loop
->scan_start
; p
!= insn
; p
= NEXT_INSN (p
))
3531 if (INSN_P (p
) && reg_overlap_mentioned_p (reg
, PATTERN (p
)))
3542 /* Information we collect about arrays that we might want to prefetch. */
3543 struct prefetch_info
3545 struct iv_class
*class; /* Class this prefetch is based on. */
3546 struct induction
*giv
; /* GIV this prefetch is based on. */
3547 rtx base_address
; /* Start prefetching from this address plus
3549 HOST_WIDE_INT index
;
3550 HOST_WIDE_INT stride
; /* Prefetch stride in bytes in each
3552 unsigned int bytes_accesed
; /* Sum of sizes of all acceses to this
3553 prefetch area in one iteration. */
3554 unsigned int total_bytes
; /* Total bytes loop will access in this block.
3555 This is set only for loops with known
3556 iteration counts and is 0xffffffff
3558 unsigned int write
: 1; /* 1 for read/write prefetches. */
3559 unsigned int prefetch_in_loop
: 1;
3560 /* 1 for those chosen for prefetching. */
3561 unsigned int prefetch_before_loop
: 1;
3562 /* 1 for those chosen for prefetching. */
3565 /* Data used by check_store function. */
3566 struct check_store_data
3572 static void check_store
PARAMS ((rtx
, rtx
, void *));
3573 static void emit_prefetch_instructions
PARAMS ((struct loop
*));
3574 static int rtx_equal_for_prefetch_p
PARAMS ((rtx
, rtx
));
3576 /* Set mem_write when mem_address is found. Used as callback to
3579 check_store (x
, pat
, data
)
3580 rtx x
, pat ATTRIBUTE_UNUSED
;
3583 struct check_store_data
*d
= (struct check_store_data
*) data
;
3585 if ((GET_CODE (x
) == MEM
) && rtx_equal_p (d
->mem_address
, XEXP (x
, 0)))
3589 /* Like rtx_equal_p, but attempts to swap commutative operands. This is
3590 important to get some addresses combined. Later more sophisticated
3591 transformations can be added when necesary.
3593 ??? Same trick with swapping operand is done at several other places.
3594 It can be nice to develop some common way to handle this. */
3597 rtx_equal_for_prefetch_p (x
, y
)
3602 enum rtx_code code
= GET_CODE (x
);
3607 if (code
!= GET_CODE (y
))
3610 code
= GET_CODE (x
);
3612 if (GET_RTX_CLASS (code
) == 'c')
3614 return ((rtx_equal_for_prefetch_p (XEXP (x
, 0), XEXP (y
, 0))
3615 && rtx_equal_for_prefetch_p (XEXP (x
, 1), XEXP (y
, 1)))
3616 || (rtx_equal_for_prefetch_p (XEXP (x
, 0), XEXP (y
, 1))
3617 && rtx_equal_for_prefetch_p (XEXP (x
, 1), XEXP (y
, 0))));
3619 /* Compare the elements. If any pair of corresponding elements fails to
3620 match, return 0 for the whole thing. */
3622 fmt
= GET_RTX_FORMAT (code
);
3623 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3628 if (XWINT (x
, i
) != XWINT (y
, i
))
3633 if (XINT (x
, i
) != XINT (y
, i
))
3638 /* Two vectors must have the same length. */
3639 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
3642 /* And the corresponding elements must match. */
3643 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3644 if (rtx_equal_for_prefetch_p (XVECEXP (x
, i
, j
),
3645 XVECEXP (y
, i
, j
)) == 0)
3650 if (rtx_equal_for_prefetch_p (XEXP (x
, i
), XEXP (y
, i
)) == 0)
3655 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
3660 /* These are just backpointers, so they don't matter. */
3666 /* It is believed that rtx's at this level will never
3667 contain anything but integers and other rtx's,
3668 except for within LABEL_REFs and SYMBOL_REFs. */
3676 /* Remove constant addition value from the expression X (when present)
3679 static HOST_WIDE_INT
3680 remove_constant_addition (x
)
3683 HOST_WIDE_INT addval
= 0;
3686 /* Avoid clobbering a shared CONST expression. */
3687 if (GET_CODE (exp
) == CONST
)
3689 if (GET_CODE (XEXP (exp
, 0)) == PLUS
3690 && GET_CODE (XEXP (XEXP (exp
, 0), 0)) == SYMBOL_REF
3691 && GET_CODE (XEXP (XEXP (exp
, 0), 1)) == CONST_INT
)
3693 *x
= XEXP (XEXP (exp
, 0), 0);
3694 return INTVAL (XEXP (XEXP (exp
, 0), 1));
3699 if (GET_CODE (exp
) == CONST_INT
)
3701 addval
= INTVAL (exp
);
3705 /* For plus expression recurse on ourself. */
3706 else if (GET_CODE (exp
) == PLUS
)
3708 addval
+= remove_constant_addition (&XEXP (exp
, 0));
3709 addval
+= remove_constant_addition (&XEXP (exp
, 1));
3711 /* In case our parameter was constant, remove extra zero from the
3713 if (XEXP (exp
, 0) == const0_rtx
)
3715 else if (XEXP (exp
, 1) == const0_rtx
)
3722 /* Attempt to identify accesses to arrays that are most likely to cause cache
3723 misses, and emit prefetch instructions a few prefetch blocks forward.
3725 To detect the arrays we use the GIV information that was collected by the
3726 strength reduction pass.
3728 The prefetch instructions are generated after the GIV information is done
3729 and before the strength reduction process. The new GIVs are injected into
3730 the strength reduction tables, so the prefetch addresses are optimized as
3733 GIVs are split into base address, stride, and constant addition values.
3734 GIVs with the same address, stride and close addition values are combined
3735 into a single prefetch. Also writes to GIVs are detected, so that prefetch
3736 for write instructions can be used for the block we write to, on machines
3737 that support write prefetches.
3739 Several heuristics are used to determine when to prefetch. They are
3740 controlled by defined symbols that can be overridden for each target. */
3743 emit_prefetch_instructions (loop
)
3746 int num_prefetches
= 0;
3747 int num_real_prefetches
= 0;
3748 int num_real_write_prefetches
= 0;
3751 struct iv_class
*bl
;
3752 struct induction
*iv
;
3753 struct prefetch_info info
[MAX_PREFETCHES
];
3754 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
3759 /* Consider only loops w/o calls. When a call is done, the loop is probably
3760 slow enough to read the memory. */
3761 if (PREFETCH_NO_CALL
&& LOOP_INFO (loop
)->has_call
)
3763 if (loop_dump_stream
)
3764 fprintf (loop_dump_stream
, "Prefetch: ignoring loop - has call.\n");
3769 if (PREFETCH_NO_LOW_LOOPCNT
3770 && LOOP_INFO (loop
)->n_iterations
3771 && LOOP_INFO (loop
)->n_iterations
<= PREFETCH_LOW_LOOPCNT
)
3773 if (loop_dump_stream
)
3774 fprintf (loop_dump_stream
,
3775 "Prefetch: ignoring loop - not enought iterations.\n");
3779 /* Search all induction variables and pick those interesting for the prefetch
3781 for (bl
= ivs
->list
; bl
; bl
= bl
->next
)
3783 struct induction
*biv
= bl
->biv
, *biv1
;
3788 /* Expect all BIVs to be executed in each iteration. This makes our
3789 analysis more conservative. */
3792 /* Discard non-constant additions that we can't handle well yet, and
3793 BIVs that are executed multiple times; such BIVs ought to be
3794 handled in the nested loop. We accept not_every_iteration BIVs,
3795 since these only result in larger strides and make our
3796 heuristics more conservative.
3797 ??? What does the last sentence mean? */
3798 if (GET_CODE (biv
->add_val
) != CONST_INT
)
3800 if (loop_dump_stream
)
3802 fprintf (loop_dump_stream
,
3803 "Prefetch: biv %i ignored: non-constant addition at insn %i:",
3804 REGNO (biv
->src_reg
), INSN_UID (biv
->insn
));
3805 print_rtl (loop_dump_stream
, biv
->add_val
);
3806 fprintf (loop_dump_stream
, "\n");
3811 if (biv
->maybe_multiple
)
3813 if (loop_dump_stream
)
3815 fprintf (loop_dump_stream
,
3816 "Prefetch: biv %i ignored: maybe_multiple at insn %i:",
3817 REGNO (biv
->src_reg
), INSN_UID (biv
->insn
));
3818 print_rtl (loop_dump_stream
, biv
->add_val
);
3819 fprintf (loop_dump_stream
, "\n");
3824 basestride
+= INTVAL (biv1
->add_val
);
3825 biv1
= biv1
->next_iv
;
3828 if (biv1
|| !basestride
)
3831 for (iv
= bl
->giv
; iv
; iv
= iv
->next_iv
)
3835 HOST_WIDE_INT index
= 0;
3837 HOST_WIDE_INT stride
;
3838 struct check_store_data d
;
3839 int size
= GET_MODE_SIZE (GET_MODE (iv
));
3841 /* There are several reasons why an induction variable is not
3842 interesting to us. */
3843 if (iv
->giv_type
!= DEST_ADDR
3844 /* We are interested only in constant stride memory references
3845 in order to be able to compute density easily. */
3846 || GET_CODE (iv
->mult_val
) != CONST_INT
3847 /* Don't handle reversed order prefetches, since they are usually
3848 ineffective. Later we may be able to reverse such BIVs. */
3849 || (PREFETCH_NO_REVERSE_ORDER
3850 && (stride
= INTVAL (iv
->mult_val
) * basestride
) < 0)
3851 /* Prefetching of accesses with such an extreme stride is probably
3852 not worthwhile, either. */
3853 || (PREFETCH_NO_EXTREME_STRIDE
3854 && stride
> PREFETCH_EXTREME_STRIDE
)
3855 /* Ignore GIVs with varying add values; we can't predict the
3856 value for the next iteration. */
3857 || !loop_invariant_p (loop
, iv
->add_val
)
3858 /* Ignore GIVs in the nested loops; they ought to have been
3860 || iv
->maybe_multiple
)
3862 if (loop_dump_stream
)
3863 fprintf (loop_dump_stream
, "Prefetch: Ignoring giv at %i\n",
3864 INSN_UID (iv
->insn
));
3868 /* Determine the pointer to the basic array we are examining. It is
3869 the sum of the BIV's initial value and the GIV's add_val. */
3872 address
= copy_rtx (iv
->add_val
);
3873 temp
= copy_rtx (bl
->initial_value
);
3875 address
= simplify_gen_binary (PLUS
, Pmode
, temp
, address
);
3876 index
= remove_constant_addition (&address
);
3880 d
.mem_address
= *iv
->location
;
3882 /* When the GIV is not always executed, we might be better off by
3883 not dirtying the cache pages. */
3884 if (PREFETCH_NOT_ALWAYS
|| iv
->always_executed
)
3885 note_stores (PATTERN (iv
->insn
), check_store
, &d
);
3887 /* Attempt to find another prefetch to the same array and see if we
3888 can merge this one. */
3889 for (i
= 0; i
< num_prefetches
; i
++)
3890 if (rtx_equal_for_prefetch_p (address
, info
[i
].base_address
)
3891 && stride
== info
[i
].stride
)
3893 /* In case both access same array (same location
3894 just with small difference in constant indexes), merge
3895 the prefetches. Just do the later and the earlier will
3896 get prefetched from previous iteration.
3897 4096 is artificial threshold. It should not be too small,
3898 but also not bigger than small portion of memory usually
3899 traversed by single loop. */
3900 if (index
>= info
[i
].index
&& index
- info
[i
].index
< 4096)
3902 info
[i
].write
|= d
.mem_write
;
3903 info
[i
].bytes_accesed
+= size
;
3904 info
[i
].index
= index
;
3907 info
[num_prefetches
].base_address
= address
;
3912 if (index
< info
[i
].index
&& info
[i
].index
- index
< 4096)
3914 info
[i
].write
|= d
.mem_write
;
3915 info
[i
].bytes_accesed
+= size
;
3921 /* Merging failed. */
3924 info
[num_prefetches
].giv
= iv
;
3925 info
[num_prefetches
].class = bl
;
3926 info
[num_prefetches
].index
= index
;
3927 info
[num_prefetches
].stride
= stride
;
3928 info
[num_prefetches
].base_address
= address
;
3929 info
[num_prefetches
].write
= d
.mem_write
;
3930 info
[num_prefetches
].bytes_accesed
= size
;
3932 if (num_prefetches
>= MAX_PREFETCHES
)
3934 if (loop_dump_stream
)
3935 fprintf (loop_dump_stream
,
3936 "Maximal number of prefetches exceeded.\n");
3943 for (i
= 0; i
< num_prefetches
; i
++)
3945 /* Attempt to calculate the number of bytes fetched by the loop.
3947 if (LOOP_INFO (loop
)->n_iterations
3948 && ((unsigned HOST_WIDE_INT
) (0xffffffff / info
[i
].stride
)
3949 >= LOOP_INFO (loop
)->n_iterations
))
3950 info
[i
].total_bytes
= info
[i
].stride
* LOOP_INFO (loop
)->n_iterations
;
3952 info
[i
].total_bytes
= 0xffffffff;
3954 /* Prefetch is worthwhile only when the loads/stores are dense. */
3955 if (PREFETCH_ONLY_DENSE_MEM
3956 && info
[i
].bytes_accesed
* 256 / info
[i
].stride
> PREFETCH_DENSE_MEM
3957 && (info
[i
].total_bytes
/ PREFETCH_BLOCK
3958 >= PREFETCH_BLOCKS_BEFORE_LOOP_MIN
))
3960 info
[i
].prefetch_before_loop
= 1;
3961 info
[i
].prefetch_in_loop
3962 = (info
[i
].total_bytes
/ PREFETCH_BLOCK
3963 > PREFETCH_BLOCKS_BEFORE_LOOP_MAX
);
3966 info
[i
].prefetch_in_loop
= 0, info
[i
].prefetch_before_loop
= 0;
3968 if (info
[i
].prefetch_in_loop
)
3970 num_real_prefetches
+= ((info
[i
].stride
+ PREFETCH_BLOCK
- 1)
3973 num_real_write_prefetches
3974 += (info
[i
].stride
+ PREFETCH_BLOCK
- 1) / PREFETCH_BLOCK
;
3978 if (loop_dump_stream
)
3980 for (i
= 0; i
< num_prefetches
; i
++)
3982 fprintf (loop_dump_stream
, "Prefetch insn %i address: ",
3983 INSN_UID (info
[i
].giv
->insn
));
3984 print_rtl (loop_dump_stream
, info
[i
].base_address
);
3985 fprintf (loop_dump_stream
, " Index: ");
3986 fprintf (loop_dump_stream
, HOST_WIDE_INT_PRINT_DEC
, info
[i
].index
);
3987 fprintf (loop_dump_stream
, " stride: ");
3988 fprintf (loop_dump_stream
, HOST_WIDE_INT_PRINT_DEC
, info
[i
].stride
);
3989 fprintf (loop_dump_stream
,
3990 " density: %i%% total_bytes: %u%sin loop: %s before: %s\n",
3991 (int) (info
[i
].bytes_accesed
* 100 / info
[i
].stride
),
3992 info
[i
].total_bytes
,
3993 info
[i
].write
? " read/write " : " read only ",
3994 info
[i
].prefetch_in_loop
? "yes" : "no",
3995 info
[i
].prefetch_before_loop
? "yes" : "no");
3998 fprintf (loop_dump_stream
, "Real prefetches needed: %i (write: %i)\n",
3999 num_real_prefetches
, num_real_write_prefetches
);
4002 if (!num_real_prefetches
)
4005 ahead
= SIMULTANEOUS_PREFETCHES
/ num_real_prefetches
;
4010 for (i
= 0; i
< num_prefetches
; i
++)
4012 if (info
[i
].prefetch_in_loop
)
4016 for (y
= 0; y
< ((info
[i
].stride
+ PREFETCH_BLOCK
- 1)
4017 / PREFETCH_BLOCK
); y
++)
4019 rtx loc
= copy_rtx (*info
[i
].giv
->location
);
4021 int bytes_ahead
= PREFETCH_BLOCK
* (ahead
+ y
);
4022 rtx before_insn
= info
[i
].giv
->insn
;
4023 rtx prev_insn
= PREV_INSN (info
[i
].giv
->insn
);
4025 /* We can save some effort by offsetting the address on
4026 architectures with offsettable memory references. */
4027 if (offsettable_address_p (0, VOIDmode
, loc
))
4028 loc
= plus_constant (loc
, bytes_ahead
);
4031 rtx reg
= gen_reg_rtx (Pmode
);
4032 loop_iv_add_mult_emit_before (loop
, loc
, const1_rtx
,
4033 GEN_INT (bytes_ahead
), reg
,
4038 /* Make sure the address operand is valid for prefetch. */
4039 if (! (*insn_data
[(int)CODE_FOR_prefetch
].operand
[0].predicate
)
4041 insn_data
[(int)CODE_FOR_prefetch
].operand
[0].mode
))
4042 loc
= force_reg (Pmode
, loc
);
4043 emit_insn_before (gen_prefetch (loc
, GEN_INT (info
[i
].write
),
4047 /* Check all insns emitted and record the new GIV
4049 insn
= NEXT_INSN (prev_insn
);
4050 while (insn
!= before_insn
)
4052 insn
= check_insn_for_givs (loop
, insn
,
4053 info
[i
].giv
->always_executed
,
4054 info
[i
].giv
->maybe_multiple
);
4055 insn
= NEXT_INSN (insn
);
4060 if (info
[i
].prefetch_before_loop
)
4064 /* Emit INSNs before the loop to fetch the first cache lines. */
4066 (!info
[i
].prefetch_in_loop
|| y
< ahead
)
4067 && y
* PREFETCH_BLOCK
< (int) info
[i
].total_bytes
; y
++)
4069 rtx reg
= gen_reg_rtx (Pmode
);
4070 rtx loop_start
= loop
->start
;
4071 rtx add_val
= simplify_gen_binary (PLUS
, Pmode
,
4072 info
[i
].giv
->add_val
,
4073 GEN_INT (y
* PREFETCH_BLOCK
));
4075 loop_iv_add_mult_emit_before (loop
, info
[i
].class->initial_value
,
4076 info
[i
].giv
->mult_val
,
4077 add_val
, reg
, 0, loop_start
);
4078 emit_insn_before (gen_prefetch (reg
, GEN_INT (info
[i
].write
),
4088 /* A "basic induction variable" or biv is a pseudo reg that is set
4089 (within this loop) only by incrementing or decrementing it. */
4090 /* A "general induction variable" or giv is a pseudo reg whose
4091 value is a linear function of a biv. */
4093 /* Bivs are recognized by `basic_induction_var';
4094 Givs by `general_induction_var'. */
4096 /* Communication with routines called via `note_stores'. */
4098 static rtx note_insn
;
4100 /* Dummy register to have non-zero DEST_REG for DEST_ADDR type givs. */
4102 static rtx addr_placeholder
;
4104 /* ??? Unfinished optimizations, and possible future optimizations,
4105 for the strength reduction code. */
4107 /* ??? The interaction of biv elimination, and recognition of 'constant'
4108 bivs, may cause problems. */
4110 /* ??? Add heuristics so that DEST_ADDR strength reduction does not cause
4111 performance problems.
4113 Perhaps don't eliminate things that can be combined with an addressing
4114 mode. Find all givs that have the same biv, mult_val, and add_val;
4115 then for each giv, check to see if its only use dies in a following
4116 memory address. If so, generate a new memory address and check to see
4117 if it is valid. If it is valid, then store the modified memory address,
4118 otherwise, mark the giv as not done so that it will get its own iv. */
4120 /* ??? Could try to optimize branches when it is known that a biv is always
4123 /* ??? When replace a biv in a compare insn, we should replace with closest
4124 giv so that an optimized branch can still be recognized by the combiner,
4125 e.g. the VAX acb insn. */
4127 /* ??? Many of the checks involving uid_luid could be simplified if regscan
4128 was rerun in loop_optimize whenever a register was added or moved.
4129 Also, some of the optimizations could be a little less conservative. */
4131 /* Scan the loop body and call FNCALL for each insn. In the addition to the
4132 LOOP and INSN parameters pass MAYBE_MULTIPLE and NOT_EVERY_ITERATION to the
4135 NOT_EVERY_ITERATION if current insn is not executed at least once for every
4136 loop iteration except for the last one.
4138 MAYBE_MULTIPLE is 1 if current insn may be executed more than once for every
4142 for_each_insn_in_loop (loop
, fncall
)
4144 loop_insn_callback fncall
;
4146 /* This is 1 if current insn is not executed at least once for every loop
4148 int not_every_iteration
= 0;
4149 int maybe_multiple
= 0;
4150 int past_loop_latch
= 0;
4154 /* If loop_scan_start points to the loop exit test, we have to be wary of
4155 subversive use of gotos inside expression statements. */
4156 if (prev_nonnote_insn (loop
->scan_start
) != prev_nonnote_insn (loop
->start
))
4157 maybe_multiple
= back_branch_in_range_p (loop
, loop
->scan_start
);
4159 /* Scan through loop to find all possible bivs. */
4161 for (p
= next_insn_in_loop (loop
, loop
->scan_start
);
4163 p
= next_insn_in_loop (loop
, p
))
4165 p
= fncall (loop
, p
, not_every_iteration
, maybe_multiple
);
4167 /* Past CODE_LABEL, we get to insns that may be executed multiple
4168 times. The only way we can be sure that they can't is if every
4169 jump insn between here and the end of the loop either
4170 returns, exits the loop, is a jump to a location that is still
4171 behind the label, or is a jump to the loop start. */
4173 if (GET_CODE (p
) == CODE_LABEL
)
4181 insn
= NEXT_INSN (insn
);
4182 if (insn
== loop
->scan_start
)
4184 if (insn
== loop
->end
)
4190 if (insn
== loop
->scan_start
)
4194 if (GET_CODE (insn
) == JUMP_INSN
4195 && GET_CODE (PATTERN (insn
)) != RETURN
4196 && (!any_condjump_p (insn
)
4197 || (JUMP_LABEL (insn
) != 0
4198 && JUMP_LABEL (insn
) != loop
->scan_start
4199 && !loop_insn_first_p (p
, JUMP_LABEL (insn
)))))
4207 /* Past a jump, we get to insns for which we can't count
4208 on whether they will be executed during each iteration. */
4209 /* This code appears twice in strength_reduce. There is also similar
4210 code in scan_loop. */
4211 if (GET_CODE (p
) == JUMP_INSN
4212 /* If we enter the loop in the middle, and scan around to the
4213 beginning, don't set not_every_iteration for that.
4214 This can be any kind of jump, since we want to know if insns
4215 will be executed if the loop is executed. */
4216 && !(JUMP_LABEL (p
) == loop
->top
4217 && ((NEXT_INSN (NEXT_INSN (p
)) == loop
->end
4218 && any_uncondjump_p (p
))
4219 || (NEXT_INSN (p
) == loop
->end
&& any_condjump_p (p
)))))
4223 /* If this is a jump outside the loop, then it also doesn't
4224 matter. Check to see if the target of this branch is on the
4225 loop->exits_labels list. */
4227 for (label
= loop
->exit_labels
; label
; label
= LABEL_NEXTREF (label
))
4228 if (XEXP (label
, 0) == JUMP_LABEL (p
))
4232 not_every_iteration
= 1;
4235 else if (GET_CODE (p
) == NOTE
)
4237 /* At the virtual top of a converted loop, insns are again known to
4238 be executed each iteration: logically, the loop begins here
4239 even though the exit code has been duplicated.
4241 Insns are also again known to be executed each iteration at
4242 the LOOP_CONT note. */
4243 if ((NOTE_LINE_NUMBER (p
) == NOTE_INSN_LOOP_VTOP
4244 || NOTE_LINE_NUMBER (p
) == NOTE_INSN_LOOP_CONT
)
4246 not_every_iteration
= 0;
4247 else if (NOTE_LINE_NUMBER (p
) == NOTE_INSN_LOOP_BEG
)
4249 else if (NOTE_LINE_NUMBER (p
) == NOTE_INSN_LOOP_END
)
4253 /* Note if we pass a loop latch. If we do, then we can not clear
4254 NOT_EVERY_ITERATION below when we pass the last CODE_LABEL in
4255 a loop since a jump before the last CODE_LABEL may have started
4256 a new loop iteration.
4258 Note that LOOP_TOP is only set for rotated loops and we need
4259 this check for all loops, so compare against the CODE_LABEL
4260 which immediately follows LOOP_START. */
4261 if (GET_CODE (p
) == JUMP_INSN
4262 && JUMP_LABEL (p
) == NEXT_INSN (loop
->start
))
4263 past_loop_latch
= 1;
4265 /* Unlike in the code motion pass where MAYBE_NEVER indicates that
4266 an insn may never be executed, NOT_EVERY_ITERATION indicates whether
4267 or not an insn is known to be executed each iteration of the
4268 loop, whether or not any iterations are known to occur.
4270 Therefore, if we have just passed a label and have no more labels
4271 between here and the test insn of the loop, and we have not passed
4272 a jump to the top of the loop, then we know these insns will be
4273 executed each iteration. */
4275 if (not_every_iteration
4277 && GET_CODE (p
) == CODE_LABEL
4278 && no_labels_between_p (p
, loop
->end
)
4279 && loop_insn_first_p (p
, loop
->cont
))
4280 not_every_iteration
= 0;
4285 loop_bivs_find (loop
)
4288 struct loop_regs
*regs
= LOOP_REGS (loop
);
4289 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
4290 /* Temporary list pointers for traversing ivs->list. */
4291 struct iv_class
*bl
, **backbl
;
4295 for_each_insn_in_loop (loop
, check_insn_for_bivs
);
4297 /* Scan ivs->list to remove all regs that proved not to be bivs.
4298 Make a sanity check against regs->n_times_set. */
4299 for (backbl
= &ivs
->list
, bl
= *backbl
; bl
; bl
= bl
->next
)
4301 if (REG_IV_TYPE (ivs
, bl
->regno
) != BASIC_INDUCT
4302 /* Above happens if register modified by subreg, etc. */
4303 /* Make sure it is not recognized as a basic induction var: */
4304 || regs
->array
[bl
->regno
].n_times_set
!= bl
->biv_count
4305 /* If never incremented, it is invariant that we decided not to
4306 move. So leave it alone. */
4307 || ! bl
->incremented
)
4309 if (loop_dump_stream
)
4310 fprintf (loop_dump_stream
, "Biv %d: discarded, %s\n",
4312 (REG_IV_TYPE (ivs
, bl
->regno
) != BASIC_INDUCT
4313 ? "not induction variable"
4314 : (! bl
->incremented
? "never incremented"
4317 REG_IV_TYPE (ivs
, bl
->regno
) = NOT_BASIC_INDUCT
;
4324 if (loop_dump_stream
)
4325 fprintf (loop_dump_stream
, "Biv %d: verified\n", bl
->regno
);
4331 /* Determine how BIVS are initialised by looking through pre-header
4332 extended basic block. */
4334 loop_bivs_init_find (loop
)
4337 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
4338 /* Temporary list pointers for traversing ivs->list. */
4339 struct iv_class
*bl
;
4343 /* Find initial value for each biv by searching backwards from loop_start,
4344 halting at first label. Also record any test condition. */
4347 for (p
= loop
->start
; p
&& GET_CODE (p
) != CODE_LABEL
; p
= PREV_INSN (p
))
4353 if (GET_CODE (p
) == CALL_INSN
)
4357 note_stores (PATTERN (p
), record_initial
, ivs
);
4359 /* Record any test of a biv that branches around the loop if no store
4360 between it and the start of loop. We only care about tests with
4361 constants and registers and only certain of those. */
4362 if (GET_CODE (p
) == JUMP_INSN
4363 && JUMP_LABEL (p
) != 0
4364 && next_real_insn (JUMP_LABEL (p
)) == next_real_insn (loop
->end
)
4365 && (test
= get_condition_for_loop (loop
, p
)) != 0
4366 && GET_CODE (XEXP (test
, 0)) == REG
4367 && REGNO (XEXP (test
, 0)) < max_reg_before_loop
4368 && (bl
= REG_IV_CLASS (ivs
, REGNO (XEXP (test
, 0)))) != 0
4369 && valid_initial_value_p (XEXP (test
, 1), p
, call_seen
, loop
->start
)
4370 && bl
->init_insn
== 0)
4372 /* If an NE test, we have an initial value! */
4373 if (GET_CODE (test
) == NE
)
4376 bl
->init_set
= gen_rtx_SET (VOIDmode
,
4377 XEXP (test
, 0), XEXP (test
, 1));
4380 bl
->initial_test
= test
;
4386 /* Look at the each biv and see if we can say anything better about its
4387 initial value from any initializing insns set up above. (This is done
4388 in two passes to avoid missing SETs in a PARALLEL.) */
4390 loop_bivs_check (loop
)
4393 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
4394 /* Temporary list pointers for traversing ivs->list. */
4395 struct iv_class
*bl
;
4396 struct iv_class
**backbl
;
4398 for (backbl
= &ivs
->list
; (bl
= *backbl
); backbl
= &bl
->next
)
4403 if (! bl
->init_insn
)
4406 /* IF INIT_INSN has a REG_EQUAL or REG_EQUIV note and the value
4407 is a constant, use the value of that. */
4408 if (((note
= find_reg_note (bl
->init_insn
, REG_EQUAL
, 0)) != NULL
4409 && CONSTANT_P (XEXP (note
, 0)))
4410 || ((note
= find_reg_note (bl
->init_insn
, REG_EQUIV
, 0)) != NULL
4411 && CONSTANT_P (XEXP (note
, 0))))
4412 src
= XEXP (note
, 0);
4414 src
= SET_SRC (bl
->init_set
);
4416 if (loop_dump_stream
)
4417 fprintf (loop_dump_stream
,
4418 "Biv %d: initialized at insn %d: initial value ",
4419 bl
->regno
, INSN_UID (bl
->init_insn
));
4421 if ((GET_MODE (src
) == GET_MODE (regno_reg_rtx
[bl
->regno
])
4422 || GET_MODE (src
) == VOIDmode
)
4423 && valid_initial_value_p (src
, bl
->init_insn
,
4424 LOOP_INFO (loop
)->pre_header_has_call
,
4427 bl
->initial_value
= src
;
4429 if (loop_dump_stream
)
4431 print_simple_rtl (loop_dump_stream
, src
);
4432 fputc ('\n', loop_dump_stream
);
4435 /* If we can't make it a giv,
4436 let biv keep initial value of "itself". */
4437 else if (loop_dump_stream
)
4438 fprintf (loop_dump_stream
, "is complex\n");
4443 /* Search the loop for general induction variables. */
4446 loop_givs_find (loop
)
4449 for_each_insn_in_loop (loop
, check_insn_for_givs
);
4453 /* For each giv for which we still don't know whether or not it is
4454 replaceable, check to see if it is replaceable because its final value
4455 can be calculated. */
4458 loop_givs_check (loop
)
4461 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
4462 struct iv_class
*bl
;
4464 for (bl
= ivs
->list
; bl
; bl
= bl
->next
)
4466 struct induction
*v
;
4468 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
4469 if (! v
->replaceable
&& ! v
->not_replaceable
)
4470 check_final_value (loop
, v
);
4475 /* Return non-zero if it is possible to eliminate the biv BL provided
4476 all givs are reduced. This is possible if either the reg is not
4477 used outside the loop, or we can compute what its final value will
4481 loop_biv_eliminable_p (loop
, bl
, threshold
, insn_count
)
4483 struct iv_class
*bl
;
4487 /* For architectures with a decrement_and_branch_until_zero insn,
4488 don't do this if we put a REG_NONNEG note on the endtest for this
4491 #ifdef HAVE_decrement_and_branch_until_zero
4494 if (loop_dump_stream
)
4495 fprintf (loop_dump_stream
,
4496 "Cannot eliminate nonneg biv %d.\n", bl
->regno
);
4501 /* Check that biv is used outside loop or if it has a final value.
4502 Compare against bl->init_insn rather than loop->start. We aren't
4503 concerned with any uses of the biv between init_insn and
4504 loop->start since these won't be affected by the value of the biv
4505 elsewhere in the function, so long as init_insn doesn't use the
4508 if ((REGNO_LAST_LUID (bl
->regno
) < INSN_LUID (loop
->end
)
4510 && INSN_UID (bl
->init_insn
) < max_uid_for_loop
4511 && REGNO_FIRST_LUID (bl
->regno
) >= INSN_LUID (bl
->init_insn
)
4512 && ! reg_mentioned_p (bl
->biv
->dest_reg
, SET_SRC (bl
->init_set
)))
4513 || (bl
->final_value
= final_biv_value (loop
, bl
)))
4514 return maybe_eliminate_biv (loop
, bl
, 0, threshold
, insn_count
);
4516 if (loop_dump_stream
)
4518 fprintf (loop_dump_stream
,
4519 "Cannot eliminate biv %d.\n",
4521 fprintf (loop_dump_stream
,
4522 "First use: insn %d, last use: insn %d.\n",
4523 REGNO_FIRST_UID (bl
->regno
),
4524 REGNO_LAST_UID (bl
->regno
));
4530 /* Reduce each giv of BL that we have decided to reduce. */
4533 loop_givs_reduce (loop
, bl
)
4535 struct iv_class
*bl
;
4537 struct induction
*v
;
4539 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
4541 struct induction
*tv
;
4542 if (! v
->ignore
&& v
->same
== 0)
4544 int auto_inc_opt
= 0;
4546 /* If the code for derived givs immediately below has already
4547 allocated a new_reg, we must keep it. */
4549 v
->new_reg
= gen_reg_rtx (v
->mode
);
4552 /* If the target has auto-increment addressing modes, and
4553 this is an address giv, then try to put the increment
4554 immediately after its use, so that flow can create an
4555 auto-increment addressing mode. */
4556 if (v
->giv_type
== DEST_ADDR
&& bl
->biv_count
== 1
4557 && bl
->biv
->always_executed
&& ! bl
->biv
->maybe_multiple
4558 /* We don't handle reversed biv's because bl->biv->insn
4559 does not have a valid INSN_LUID. */
4561 && v
->always_executed
&& ! v
->maybe_multiple
4562 && INSN_UID (v
->insn
) < max_uid_for_loop
)
4564 /* If other giv's have been combined with this one, then
4565 this will work only if all uses of the other giv's occur
4566 before this giv's insn. This is difficult to check.
4568 We simplify this by looking for the common case where
4569 there is one DEST_REG giv, and this giv's insn is the
4570 last use of the dest_reg of that DEST_REG giv. If the
4571 increment occurs after the address giv, then we can
4572 perform the optimization. (Otherwise, the increment
4573 would have to go before other_giv, and we would not be
4574 able to combine it with the address giv to get an
4575 auto-inc address.) */
4576 if (v
->combined_with
)
4578 struct induction
*other_giv
= 0;
4580 for (tv
= bl
->giv
; tv
; tv
= tv
->next_iv
)
4588 if (! tv
&& other_giv
4589 && REGNO (other_giv
->dest_reg
) < max_reg_before_loop
4590 && (REGNO_LAST_UID (REGNO (other_giv
->dest_reg
))
4591 == INSN_UID (v
->insn
))
4592 && INSN_LUID (v
->insn
) < INSN_LUID (bl
->biv
->insn
))
4595 /* Check for case where increment is before the address
4596 giv. Do this test in "loop order". */
4597 else if ((INSN_LUID (v
->insn
) > INSN_LUID (bl
->biv
->insn
)
4598 && (INSN_LUID (v
->insn
) < INSN_LUID (loop
->scan_start
)
4599 || (INSN_LUID (bl
->biv
->insn
)
4600 > INSN_LUID (loop
->scan_start
))))
4601 || (INSN_LUID (v
->insn
) < INSN_LUID (loop
->scan_start
)
4602 && (INSN_LUID (loop
->scan_start
)
4603 < INSN_LUID (bl
->biv
->insn
))))
4612 /* We can't put an insn immediately after one setting
4613 cc0, or immediately before one using cc0. */
4614 if ((auto_inc_opt
== 1 && sets_cc0_p (PATTERN (v
->insn
)))
4615 || (auto_inc_opt
== -1
4616 && (prev
= prev_nonnote_insn (v
->insn
)) != 0
4618 && sets_cc0_p (PATTERN (prev
))))
4624 v
->auto_inc_opt
= 1;
4628 /* For each place where the biv is incremented, add an insn
4629 to increment the new, reduced reg for the giv. */
4630 for (tv
= bl
->biv
; tv
; tv
= tv
->next_iv
)
4635 insert_before
= tv
->insn
;
4636 else if (auto_inc_opt
== 1)
4637 insert_before
= NEXT_INSN (v
->insn
);
4639 insert_before
= v
->insn
;
4641 if (tv
->mult_val
== const1_rtx
)
4642 loop_iv_add_mult_emit_before (loop
, tv
->add_val
, v
->mult_val
,
4643 v
->new_reg
, v
->new_reg
,
4645 else /* tv->mult_val == const0_rtx */
4646 /* A multiply is acceptable here
4647 since this is presumed to be seldom executed. */
4648 loop_iv_add_mult_emit_before (loop
, tv
->add_val
, v
->mult_val
,
4649 v
->add_val
, v
->new_reg
,
4653 /* Add code at loop start to initialize giv's reduced reg. */
4655 loop_iv_add_mult_hoist (loop
,
4656 extend_value_for_giv (v
, bl
->initial_value
),
4657 v
->mult_val
, v
->add_val
, v
->new_reg
);
4663 /* Check for givs whose first use is their definition and whose
4664 last use is the definition of another giv. If so, it is likely
4665 dead and should not be used to derive another giv nor to
4669 loop_givs_dead_check (loop
, bl
)
4670 struct loop
*loop ATTRIBUTE_UNUSED
;
4671 struct iv_class
*bl
;
4673 struct induction
*v
;
4675 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
4678 || (v
->same
&& v
->same
->ignore
))
4681 if (v
->giv_type
== DEST_REG
4682 && REGNO_FIRST_UID (REGNO (v
->dest_reg
)) == INSN_UID (v
->insn
))
4684 struct induction
*v1
;
4686 for (v1
= bl
->giv
; v1
; v1
= v1
->next_iv
)
4687 if (REGNO_LAST_UID (REGNO (v
->dest_reg
)) == INSN_UID (v1
->insn
))
4695 loop_givs_rescan (loop
, bl
, reg_map
)
4697 struct iv_class
*bl
;
4700 struct induction
*v
;
4702 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
4704 if (v
->same
&& v
->same
->ignore
)
4710 /* Update expression if this was combined, in case other giv was
4713 v
->new_reg
= replace_rtx (v
->new_reg
,
4714 v
->same
->dest_reg
, v
->same
->new_reg
);
4716 /* See if this register is known to be a pointer to something. If
4717 so, see if we can find the alignment. First see if there is a
4718 destination register that is a pointer. If so, this shares the
4719 alignment too. Next see if we can deduce anything from the
4720 computational information. If not, and this is a DEST_ADDR
4721 giv, at least we know that it's a pointer, though we don't know
4723 if (GET_CODE (v
->new_reg
) == REG
4724 && v
->giv_type
== DEST_REG
4725 && REG_POINTER (v
->dest_reg
))
4726 mark_reg_pointer (v
->new_reg
,
4727 REGNO_POINTER_ALIGN (REGNO (v
->dest_reg
)));
4728 else if (GET_CODE (v
->new_reg
) == REG
4729 && REG_POINTER (v
->src_reg
))
4731 unsigned int align
= REGNO_POINTER_ALIGN (REGNO (v
->src_reg
));
4734 || GET_CODE (v
->add_val
) != CONST_INT
4735 || INTVAL (v
->add_val
) % (align
/ BITS_PER_UNIT
) != 0)
4738 mark_reg_pointer (v
->new_reg
, align
);
4740 else if (GET_CODE (v
->new_reg
) == REG
4741 && GET_CODE (v
->add_val
) == REG
4742 && REG_POINTER (v
->add_val
))
4744 unsigned int align
= REGNO_POINTER_ALIGN (REGNO (v
->add_val
));
4746 if (align
== 0 || GET_CODE (v
->mult_val
) != CONST_INT
4747 || INTVAL (v
->mult_val
) % (align
/ BITS_PER_UNIT
) != 0)
4750 mark_reg_pointer (v
->new_reg
, align
);
4752 else if (GET_CODE (v
->new_reg
) == REG
&& v
->giv_type
== DEST_ADDR
)
4753 mark_reg_pointer (v
->new_reg
, 0);
4755 if (v
->giv_type
== DEST_ADDR
)
4756 /* Store reduced reg as the address in the memref where we found
4758 validate_change (v
->insn
, v
->location
, v
->new_reg
, 0);
4759 else if (v
->replaceable
)
4761 reg_map
[REGNO (v
->dest_reg
)] = v
->new_reg
;
4765 /* Not replaceable; emit an insn to set the original giv reg from
4766 the reduced giv, same as above. */
4767 loop_insn_emit_after (loop
, 0, v
->insn
,
4768 gen_move_insn (v
->dest_reg
, v
->new_reg
));
4771 /* When a loop is reversed, givs which depend on the reversed
4772 biv, and which are live outside the loop, must be set to their
4773 correct final value. This insn is only needed if the giv is
4774 not replaceable. The correct final value is the same as the
4775 value that the giv starts the reversed loop with. */
4776 if (bl
->reversed
&& ! v
->replaceable
)
4777 loop_iv_add_mult_sink (loop
,
4778 extend_value_for_giv (v
, bl
->initial_value
),
4779 v
->mult_val
, v
->add_val
, v
->dest_reg
);
4780 else if (v
->final_value
)
4781 loop_insn_sink_or_swim (loop
,
4782 gen_move_insn (v
->dest_reg
, v
->final_value
));
4784 if (loop_dump_stream
)
4786 fprintf (loop_dump_stream
, "giv at %d reduced to ",
4787 INSN_UID (v
->insn
));
4788 print_simple_rtl (loop_dump_stream
, v
->new_reg
);
4789 fprintf (loop_dump_stream
, "\n");
4796 loop_giv_reduce_benefit (loop
, bl
, v
, test_reg
)
4797 struct loop
*loop ATTRIBUTE_UNUSED
;
4798 struct iv_class
*bl
;
4799 struct induction
*v
;
4805 benefit
= v
->benefit
;
4806 PUT_MODE (test_reg
, v
->mode
);
4807 add_cost
= iv_add_mult_cost (bl
->biv
->add_val
, v
->mult_val
,
4808 test_reg
, test_reg
);
4810 /* Reduce benefit if not replaceable, since we will insert a
4811 move-insn to replace the insn that calculates this giv. Don't do
4812 this unless the giv is a user variable, since it will often be
4813 marked non-replaceable because of the duplication of the exit
4814 code outside the loop. In such a case, the copies we insert are
4815 dead and will be deleted. So they don't have a cost. Similar
4816 situations exist. */
4817 /* ??? The new final_[bg]iv_value code does a much better job of
4818 finding replaceable giv's, and hence this code may no longer be
4820 if (! v
->replaceable
&& ! bl
->eliminable
4821 && REG_USERVAR_P (v
->dest_reg
))
4822 benefit
-= copy_cost
;
4824 /* Decrease the benefit to count the add-insns that we will insert
4825 to increment the reduced reg for the giv. ??? This can
4826 overestimate the run-time cost of the additional insns, e.g. if
4827 there are multiple basic blocks that increment the biv, but only
4828 one of these blocks is executed during each iteration. There is
4829 no good way to detect cases like this with the current structure
4830 of the loop optimizer. This code is more accurate for
4831 determining code size than run-time benefits. */
4832 benefit
-= add_cost
* bl
->biv_count
;
4834 /* Decide whether to strength-reduce this giv or to leave the code
4835 unchanged (recompute it from the biv each time it is used). This
4836 decision can be made independently for each giv. */
4839 /* Attempt to guess whether autoincrement will handle some of the
4840 new add insns; if so, increase BENEFIT (undo the subtraction of
4841 add_cost that was done above). */
4842 if (v
->giv_type
== DEST_ADDR
4843 /* Increasing the benefit is risky, since this is only a guess.
4844 Avoid increasing register pressure in cases where there would
4845 be no other benefit from reducing this giv. */
4847 && GET_CODE (v
->mult_val
) == CONST_INT
)
4849 int size
= GET_MODE_SIZE (GET_MODE (v
->mem
));
4851 if (HAVE_POST_INCREMENT
4852 && INTVAL (v
->mult_val
) == size
)
4853 benefit
+= add_cost
* bl
->biv_count
;
4854 else if (HAVE_PRE_INCREMENT
4855 && INTVAL (v
->mult_val
) == size
)
4856 benefit
+= add_cost
* bl
->biv_count
;
4857 else if (HAVE_POST_DECREMENT
4858 && -INTVAL (v
->mult_val
) == size
)
4859 benefit
+= add_cost
* bl
->biv_count
;
4860 else if (HAVE_PRE_DECREMENT
4861 && -INTVAL (v
->mult_val
) == size
)
4862 benefit
+= add_cost
* bl
->biv_count
;
4870 /* Free IV structures for LOOP. */
4873 loop_ivs_free (loop
)
4876 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
4877 struct iv_class
*iv
= ivs
->list
;
4883 struct iv_class
*next
= iv
->next
;
4884 struct induction
*induction
;
4885 struct induction
*next_induction
;
4887 for (induction
= iv
->biv
; induction
; induction
= next_induction
)
4889 next_induction
= induction
->next_iv
;
4892 for (induction
= iv
->giv
; induction
; induction
= next_induction
)
4894 next_induction
= induction
->next_iv
;
4904 /* Perform strength reduction and induction variable elimination.
4906 Pseudo registers created during this function will be beyond the
4907 last valid index in several tables including
4908 REGS->ARRAY[I].N_TIMES_SET and REGNO_LAST_UID. This does not cause a
4909 problem here, because the added registers cannot be givs outside of
4910 their loop, and hence will never be reconsidered. But scan_loop
4911 must check regnos to make sure they are in bounds. */
4914 strength_reduce (loop
, flags
)
4918 struct loop_info
*loop_info
= LOOP_INFO (loop
);
4919 struct loop_regs
*regs
= LOOP_REGS (loop
);
4920 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
4922 /* Temporary list pointer for traversing ivs->list. */
4923 struct iv_class
*bl
;
4924 /* Ratio of extra register life span we can justify
4925 for saving an instruction. More if loop doesn't call subroutines
4926 since in that case saving an insn makes more difference
4927 and more registers are available. */
4928 /* ??? could set this to last value of threshold in move_movables */
4929 int threshold
= (loop_info
->has_call
? 1 : 2) * (3 + n_non_fixed_regs
);
4930 /* Map of pseudo-register replacements. */
4931 rtx
*reg_map
= NULL
;
4933 int unrolled_insn_copies
= 0;
4934 rtx test_reg
= gen_rtx_REG (word_mode
, LAST_VIRTUAL_REGISTER
+ 1);
4935 int insn_count
= count_insns_in_loop (loop
);
4937 addr_placeholder
= gen_reg_rtx (Pmode
);
4939 ivs
->n_regs
= max_reg_before_loop
;
4940 ivs
->regs
= (struct iv
*) xcalloc (ivs
->n_regs
, sizeof (struct iv
));
4942 /* Find all BIVs in loop. */
4943 loop_bivs_find (loop
);
4945 /* Exit if there are no bivs. */
4948 /* Can still unroll the loop anyways, but indicate that there is no
4949 strength reduction info available. */
4950 if (flags
& LOOP_UNROLL
)
4951 unroll_loop (loop
, insn_count
, 0);
4953 loop_ivs_free (loop
);
4957 /* Determine how BIVS are initialised by looking through pre-header
4958 extended basic block. */
4959 loop_bivs_init_find (loop
);
4961 /* Look at the each biv and see if we can say anything better about its
4962 initial value from any initializing insns set up above. */
4963 loop_bivs_check (loop
);
4965 /* Search the loop for general induction variables. */
4966 loop_givs_find (loop
);
4968 /* Try to calculate and save the number of loop iterations. This is
4969 set to zero if the actual number can not be calculated. This must
4970 be called after all giv's have been identified, since otherwise it may
4971 fail if the iteration variable is a giv. */
4972 loop_iterations (loop
);
4974 #ifdef HAVE_prefetch
4975 if (flags
& LOOP_PREFETCH
)
4976 emit_prefetch_instructions (loop
);
4979 /* Now for each giv for which we still don't know whether or not it is
4980 replaceable, check to see if it is replaceable because its final value
4981 can be calculated. This must be done after loop_iterations is called,
4982 so that final_giv_value will work correctly. */
4983 loop_givs_check (loop
);
4985 /* Try to prove that the loop counter variable (if any) is always
4986 nonnegative; if so, record that fact with a REG_NONNEG note
4987 so that "decrement and branch until zero" insn can be used. */
4988 check_dbra_loop (loop
, insn_count
);
4990 /* Create reg_map to hold substitutions for replaceable giv regs.
4991 Some givs might have been made from biv increments, so look at
4992 ivs->reg_iv_type for a suitable size. */
4993 reg_map_size
= ivs
->n_regs
;
4994 reg_map
= (rtx
*) xcalloc (reg_map_size
, sizeof (rtx
));
4996 /* Examine each iv class for feasibility of strength reduction/induction
4997 variable elimination. */
4999 for (bl
= ivs
->list
; bl
; bl
= bl
->next
)
5001 struct induction
*v
;
5004 /* Test whether it will be possible to eliminate this biv
5005 provided all givs are reduced. */
5006 bl
->eliminable
= loop_biv_eliminable_p (loop
, bl
, threshold
, insn_count
);
5008 /* This will be true at the end, if all givs which depend on this
5009 biv have been strength reduced.
5010 We can't (currently) eliminate the biv unless this is so. */
5011 bl
->all_reduced
= 1;
5013 /* Check each extension dependent giv in this class to see if its
5014 root biv is safe from wrapping in the interior mode. */
5015 check_ext_dependent_givs (bl
, loop_info
);
5017 /* Combine all giv's for this iv_class. */
5018 combine_givs (regs
, bl
);
5020 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
5022 struct induction
*tv
;
5024 if (v
->ignore
|| v
->same
)
5027 benefit
= loop_giv_reduce_benefit (loop
, bl
, v
, test_reg
);
5029 /* If an insn is not to be strength reduced, then set its ignore
5030 flag, and clear bl->all_reduced. */
5032 /* A giv that depends on a reversed biv must be reduced if it is
5033 used after the loop exit, otherwise, it would have the wrong
5034 value after the loop exit. To make it simple, just reduce all
5035 of such giv's whether or not we know they are used after the loop
5038 if (! flag_reduce_all_givs
5039 && v
->lifetime
* threshold
* benefit
< insn_count
5042 if (loop_dump_stream
)
5043 fprintf (loop_dump_stream
,
5044 "giv of insn %d not worth while, %d vs %d.\n",
5046 v
->lifetime
* threshold
* benefit
, insn_count
);
5048 bl
->all_reduced
= 0;
5052 /* Check that we can increment the reduced giv without a
5053 multiply insn. If not, reject it. */
5055 for (tv
= bl
->biv
; tv
; tv
= tv
->next_iv
)
5056 if (tv
->mult_val
== const1_rtx
5057 && ! product_cheap_p (tv
->add_val
, v
->mult_val
))
5059 if (loop_dump_stream
)
5060 fprintf (loop_dump_stream
,
5061 "giv of insn %d: would need a multiply.\n",
5062 INSN_UID (v
->insn
));
5064 bl
->all_reduced
= 0;
5070 /* Check for givs whose first use is their definition and whose
5071 last use is the definition of another giv. If so, it is likely
5072 dead and should not be used to derive another giv nor to
5074 loop_givs_dead_check (loop
, bl
);
5076 /* Reduce each giv that we decided to reduce. */
5077 loop_givs_reduce (loop
, bl
);
5079 /* Rescan all givs. If a giv is the same as a giv not reduced, mark it
5082 For each giv register that can be reduced now: if replaceable,
5083 substitute reduced reg wherever the old giv occurs;
5084 else add new move insn "giv_reg = reduced_reg". */
5085 loop_givs_rescan (loop
, bl
, reg_map
);
5087 /* All the givs based on the biv bl have been reduced if they
5090 /* For each giv not marked as maybe dead that has been combined with a
5091 second giv, clear any "maybe dead" mark on that second giv.
5092 v->new_reg will either be or refer to the register of the giv it
5095 Doing this clearing avoids problems in biv elimination where
5096 a giv's new_reg is a complex value that can't be put in the
5097 insn but the giv combined with (with a reg as new_reg) is
5098 marked maybe_dead. Since the register will be used in either
5099 case, we'd prefer it be used from the simpler giv. */
5101 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
5102 if (! v
->maybe_dead
&& v
->same
)
5103 v
->same
->maybe_dead
= 0;
5105 /* Try to eliminate the biv, if it is a candidate.
5106 This won't work if ! bl->all_reduced,
5107 since the givs we planned to use might not have been reduced.
5109 We have to be careful that we didn't initially think we could
5110 eliminate this biv because of a giv that we now think may be
5111 dead and shouldn't be used as a biv replacement.
5113 Also, there is the possibility that we may have a giv that looks
5114 like it can be used to eliminate a biv, but the resulting insn
5115 isn't valid. This can happen, for example, on the 88k, where a
5116 JUMP_INSN can compare a register only with zero. Attempts to
5117 replace it with a compare with a constant will fail.
5119 Note that in cases where this call fails, we may have replaced some
5120 of the occurrences of the biv with a giv, but no harm was done in
5121 doing so in the rare cases where it can occur. */
5123 if (bl
->all_reduced
== 1 && bl
->eliminable
5124 && maybe_eliminate_biv (loop
, bl
, 1, threshold
, insn_count
))
5126 /* ?? If we created a new test to bypass the loop entirely,
5127 or otherwise drop straight in, based on this test, then
5128 we might want to rewrite it also. This way some later
5129 pass has more hope of removing the initialization of this
5132 /* If final_value != 0, then the biv may be used after loop end
5133 and we must emit an insn to set it just in case.
5135 Reversed bivs already have an insn after the loop setting their
5136 value, so we don't need another one. We can't calculate the
5137 proper final value for such a biv here anyways. */
5138 if (bl
->final_value
&& ! bl
->reversed
)
5139 loop_insn_sink_or_swim (loop
, gen_move_insn
5140 (bl
->biv
->dest_reg
, bl
->final_value
));
5142 if (loop_dump_stream
)
5143 fprintf (loop_dump_stream
, "Reg %d: biv eliminated\n",
5148 /* Go through all the instructions in the loop, making all the
5149 register substitutions scheduled in REG_MAP. */
5151 for (p
= loop
->start
; p
!= loop
->end
; p
= NEXT_INSN (p
))
5152 if (GET_CODE (p
) == INSN
|| GET_CODE (p
) == JUMP_INSN
5153 || GET_CODE (p
) == CALL_INSN
)
5155 replace_regs (PATTERN (p
), reg_map
, reg_map_size
, 0);
5156 replace_regs (REG_NOTES (p
), reg_map
, reg_map_size
, 0);
5160 if (loop_info
->n_iterations
> 0)
5162 /* When we completely unroll a loop we will likely not need the increment
5163 of the loop BIV and we will not need the conditional branch at the
5165 unrolled_insn_copies
= insn_count
- 2;
5168 /* When we completely unroll a loop on a HAVE_cc0 machine we will not
5169 need the comparison before the conditional branch at the end of the
5171 unrolled_insn_copies
-= 1;
5174 /* We'll need one copy for each loop iteration. */
5175 unrolled_insn_copies
*= loop_info
->n_iterations
;
5177 /* A little slop to account for the ability to remove initialization
5178 code, better CSE, and other secondary benefits of completely
5179 unrolling some loops. */
5180 unrolled_insn_copies
-= 1;
5182 /* Clamp the value. */
5183 if (unrolled_insn_copies
< 0)
5184 unrolled_insn_copies
= 0;
5187 /* Unroll loops from within strength reduction so that we can use the
5188 induction variable information that strength_reduce has already
5189 collected. Always unroll loops that would be as small or smaller
5190 unrolled than when rolled. */
5191 if ((flags
& LOOP_UNROLL
)
5192 || (loop_info
->n_iterations
> 0
5193 && unrolled_insn_copies
<= insn_count
))
5194 unroll_loop (loop
, insn_count
, 1);
5196 #ifdef HAVE_doloop_end
5197 if (HAVE_doloop_end
&& (flags
& LOOP_BCT
) && flag_branch_on_count_reg
)
5198 doloop_optimize (loop
);
5199 #endif /* HAVE_doloop_end */
5201 /* In case number of iterations is known, drop branch prediction note
5202 in the branch. Do that only in second loop pass, as loop unrolling
5203 may change the number of iterations performed. */
5204 if ((flags
& LOOP_BCT
)
5205 && loop_info
->n_iterations
/ loop_info
->unroll_number
> 1)
5207 int n
= loop_info
->n_iterations
/ loop_info
->unroll_number
;
5208 predict_insn (PREV_INSN (loop
->end
),
5209 PRED_LOOP_ITERATIONS
,
5210 REG_BR_PROB_BASE
- REG_BR_PROB_BASE
/ n
);
5213 if (loop_dump_stream
)
5214 fprintf (loop_dump_stream
, "\n");
5216 loop_ivs_free (loop
);
5221 /*Record all basic induction variables calculated in the insn. */
5223 check_insn_for_bivs (loop
, p
, not_every_iteration
, maybe_multiple
)
5226 int not_every_iteration
;
5229 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
5236 if (GET_CODE (p
) == INSN
5237 && (set
= single_set (p
))
5238 && GET_CODE (SET_DEST (set
)) == REG
)
5240 dest_reg
= SET_DEST (set
);
5241 if (REGNO (dest_reg
) < max_reg_before_loop
5242 && REGNO (dest_reg
) >= FIRST_PSEUDO_REGISTER
5243 && REG_IV_TYPE (ivs
, REGNO (dest_reg
)) != NOT_BASIC_INDUCT
)
5245 if (basic_induction_var (loop
, SET_SRC (set
),
5246 GET_MODE (SET_SRC (set
)),
5247 dest_reg
, p
, &inc_val
, &mult_val
,
5250 /* It is a possible basic induction variable.
5251 Create and initialize an induction structure for it. */
5254 = (struct induction
*) xmalloc (sizeof (struct induction
));
5256 record_biv (loop
, v
, p
, dest_reg
, inc_val
, mult_val
, location
,
5257 not_every_iteration
, maybe_multiple
);
5258 REG_IV_TYPE (ivs
, REGNO (dest_reg
)) = BASIC_INDUCT
;
5260 else if (REGNO (dest_reg
) < ivs
->n_regs
)
5261 REG_IV_TYPE (ivs
, REGNO (dest_reg
)) = NOT_BASIC_INDUCT
;
5267 /* Record all givs calculated in the insn.
5268 A register is a giv if: it is only set once, it is a function of a
5269 biv and a constant (or invariant), and it is not a biv. */
5271 check_insn_for_givs (loop
, p
, not_every_iteration
, maybe_multiple
)
5274 int not_every_iteration
;
5277 struct loop_regs
*regs
= LOOP_REGS (loop
);
5280 /* Look for a general induction variable in a register. */
5281 if (GET_CODE (p
) == INSN
5282 && (set
= single_set (p
))
5283 && GET_CODE (SET_DEST (set
)) == REG
5284 && ! regs
->array
[REGNO (SET_DEST (set
))].may_not_optimize
)
5293 rtx last_consec_insn
;
5295 dest_reg
= SET_DEST (set
);
5296 if (REGNO (dest_reg
) < FIRST_PSEUDO_REGISTER
)
5299 if (/* SET_SRC is a giv. */
5300 (general_induction_var (loop
, SET_SRC (set
), &src_reg
, &add_val
,
5301 &mult_val
, &ext_val
, 0, &benefit
, VOIDmode
)
5302 /* Equivalent expression is a giv. */
5303 || ((regnote
= find_reg_note (p
, REG_EQUAL
, NULL_RTX
))
5304 && general_induction_var (loop
, XEXP (regnote
, 0), &src_reg
,
5305 &add_val
, &mult_val
, &ext_val
, 0,
5306 &benefit
, VOIDmode
)))
5307 /* Don't try to handle any regs made by loop optimization.
5308 We have nothing on them in regno_first_uid, etc. */
5309 && REGNO (dest_reg
) < max_reg_before_loop
5310 /* Don't recognize a BASIC_INDUCT_VAR here. */
5311 && dest_reg
!= src_reg
5312 /* This must be the only place where the register is set. */
5313 && (regs
->array
[REGNO (dest_reg
)].n_times_set
== 1
5314 /* or all sets must be consecutive and make a giv. */
5315 || (benefit
= consec_sets_giv (loop
, benefit
, p
,
5317 &add_val
, &mult_val
, &ext_val
,
5318 &last_consec_insn
))))
5321 = (struct induction
*) xmalloc (sizeof (struct induction
));
5323 /* If this is a library call, increase benefit. */
5324 if (find_reg_note (p
, REG_RETVAL
, NULL_RTX
))
5325 benefit
+= libcall_benefit (p
);
5327 /* Skip the consecutive insns, if there are any. */
5328 if (regs
->array
[REGNO (dest_reg
)].n_times_set
!= 1)
5329 p
= last_consec_insn
;
5331 record_giv (loop
, v
, p
, src_reg
, dest_reg
, mult_val
, add_val
,
5332 ext_val
, benefit
, DEST_REG
, not_every_iteration
,
5333 maybe_multiple
, (rtx
*) 0);
5338 #ifndef DONT_REDUCE_ADDR
5339 /* Look for givs which are memory addresses. */
5340 /* This resulted in worse code on a VAX 8600. I wonder if it
5342 if (GET_CODE (p
) == INSN
)
5343 find_mem_givs (loop
, PATTERN (p
), p
, not_every_iteration
,
5347 /* Update the status of whether giv can derive other givs. This can
5348 change when we pass a label or an insn that updates a biv. */
5349 if (GET_CODE (p
) == INSN
|| GET_CODE (p
) == JUMP_INSN
5350 || GET_CODE (p
) == CODE_LABEL
)
5351 update_giv_derive (loop
, p
);
5355 /* Return 1 if X is a valid source for an initial value (or as value being
5356 compared against in an initial test).
5358 X must be either a register or constant and must not be clobbered between
5359 the current insn and the start of the loop.
5361 INSN is the insn containing X. */
5364 valid_initial_value_p (x
, insn
, call_seen
, loop_start
)
5373 /* Only consider pseudos we know about initialized in insns whose luids
5375 if (GET_CODE (x
) != REG
5376 || REGNO (x
) >= max_reg_before_loop
)
5379 /* Don't use call-clobbered registers across a call which clobbers it. On
5380 some machines, don't use any hard registers at all. */
5381 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
5382 && (SMALL_REGISTER_CLASSES
5383 || (call_used_regs
[REGNO (x
)] && call_seen
)))
5386 /* Don't use registers that have been clobbered before the start of the
5388 if (reg_set_between_p (x
, insn
, loop_start
))
5394 /* Scan X for memory refs and check each memory address
5395 as a possible giv. INSN is the insn whose pattern X comes from.
5396 NOT_EVERY_ITERATION is 1 if the insn might not be executed during
5397 every loop iteration. MAYBE_MULTIPLE is 1 if the insn might be executed
5398 more thanonce in each loop iteration. */
5401 find_mem_givs (loop
, x
, insn
, not_every_iteration
, maybe_multiple
)
5402 const struct loop
*loop
;
5405 int not_every_iteration
, maybe_multiple
;
5414 code
= GET_CODE (x
);
5439 /* This code used to disable creating GIVs with mult_val == 1 and
5440 add_val == 0. However, this leads to lost optimizations when
5441 it comes time to combine a set of related DEST_ADDR GIVs, since
5442 this one would not be seen. */
5444 if (general_induction_var (loop
, XEXP (x
, 0), &src_reg
, &add_val
,
5445 &mult_val
, &ext_val
, 1, &benefit
,
5448 /* Found one; record it. */
5450 = (struct induction
*) xmalloc (sizeof (struct induction
));
5452 record_giv (loop
, v
, insn
, src_reg
, addr_placeholder
, mult_val
,
5453 add_val
, ext_val
, benefit
, DEST_ADDR
,
5454 not_every_iteration
, maybe_multiple
, &XEXP (x
, 0));
5465 /* Recursively scan the subexpressions for other mem refs. */
5467 fmt
= GET_RTX_FORMAT (code
);
5468 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
5470 find_mem_givs (loop
, XEXP (x
, i
), insn
, not_every_iteration
,
5472 else if (fmt
[i
] == 'E')
5473 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
5474 find_mem_givs (loop
, XVECEXP (x
, i
, j
), insn
, not_every_iteration
,
5478 /* Fill in the data about one biv update.
5479 V is the `struct induction' in which we record the biv. (It is
5480 allocated by the caller, with alloca.)
5481 INSN is the insn that sets it.
5482 DEST_REG is the biv's reg.
5484 MULT_VAL is const1_rtx if the biv is being incremented here, in which case
5485 INC_VAL is the increment. Otherwise, MULT_VAL is const0_rtx and the biv is
5486 being set to INC_VAL.
5488 NOT_EVERY_ITERATION is nonzero if this biv update is not know to be
5489 executed every iteration; MAYBE_MULTIPLE is nonzero if this biv update
5490 can be executed more than once per iteration. If MAYBE_MULTIPLE
5491 and NOT_EVERY_ITERATION are both zero, we know that the biv update is
5492 executed exactly once per iteration. */
5495 record_biv (loop
, v
, insn
, dest_reg
, inc_val
, mult_val
, location
,
5496 not_every_iteration
, maybe_multiple
)
5498 struct induction
*v
;
5504 int not_every_iteration
;
5507 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
5508 struct iv_class
*bl
;
5511 v
->src_reg
= dest_reg
;
5512 v
->dest_reg
= dest_reg
;
5513 v
->mult_val
= mult_val
;
5514 v
->add_val
= inc_val
;
5515 v
->ext_dependent
= NULL_RTX
;
5516 v
->location
= location
;
5517 v
->mode
= GET_MODE (dest_reg
);
5518 v
->always_computable
= ! not_every_iteration
;
5519 v
->always_executed
= ! not_every_iteration
;
5520 v
->maybe_multiple
= maybe_multiple
;
5522 /* Add this to the reg's iv_class, creating a class
5523 if this is the first incrementation of the reg. */
5525 bl
= REG_IV_CLASS (ivs
, REGNO (dest_reg
));
5528 /* Create and initialize new iv_class. */
5530 bl
= (struct iv_class
*) xmalloc (sizeof (struct iv_class
));
5532 bl
->regno
= REGNO (dest_reg
);
5538 /* Set initial value to the reg itself. */
5539 bl
->initial_value
= dest_reg
;
5540 bl
->final_value
= 0;
5541 /* We haven't seen the initializing insn yet */
5544 bl
->initial_test
= 0;
5545 bl
->incremented
= 0;
5549 bl
->total_benefit
= 0;
5551 /* Add this class to ivs->list. */
5552 bl
->next
= ivs
->list
;
5555 /* Put it in the array of biv register classes. */
5556 REG_IV_CLASS (ivs
, REGNO (dest_reg
)) = bl
;
5559 /* Update IV_CLASS entry for this biv. */
5560 v
->next_iv
= bl
->biv
;
5563 if (mult_val
== const1_rtx
)
5564 bl
->incremented
= 1;
5566 if (loop_dump_stream
)
5567 loop_biv_dump (v
, loop_dump_stream
, 0);
5570 /* Fill in the data about one giv.
5571 V is the `struct induction' in which we record the giv. (It is
5572 allocated by the caller, with alloca.)
5573 INSN is the insn that sets it.
5574 BENEFIT estimates the savings from deleting this insn.
5575 TYPE is DEST_REG or DEST_ADDR; it says whether the giv is computed
5576 into a register or is used as a memory address.
5578 SRC_REG is the biv reg which the giv is computed from.
5579 DEST_REG is the giv's reg (if the giv is stored in a reg).
5580 MULT_VAL and ADD_VAL are the coefficients used to compute the giv.
5581 LOCATION points to the place where this giv's value appears in INSN. */
5584 record_giv (loop
, v
, insn
, src_reg
, dest_reg
, mult_val
, add_val
, ext_val
,
5585 benefit
, type
, not_every_iteration
, maybe_multiple
, location
)
5586 const struct loop
*loop
;
5587 struct induction
*v
;
5591 rtx mult_val
, add_val
, ext_val
;
5594 int not_every_iteration
, maybe_multiple
;
5597 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
5598 struct induction
*b
;
5599 struct iv_class
*bl
;
5600 rtx set
= single_set (insn
);
5603 /* Attempt to prove constantness of the values. Don't let simplity_rtx
5604 undo the MULT canonicalization that we performed earlier. */
5605 temp
= simplify_rtx (add_val
);
5607 && ! (GET_CODE (add_val
) == MULT
5608 && GET_CODE (temp
) == ASHIFT
))
5612 v
->src_reg
= src_reg
;
5614 v
->dest_reg
= dest_reg
;
5615 v
->mult_val
= mult_val
;
5616 v
->add_val
= add_val
;
5617 v
->ext_dependent
= ext_val
;
5618 v
->benefit
= benefit
;
5619 v
->location
= location
;
5621 v
->combined_with
= 0;
5622 v
->maybe_multiple
= maybe_multiple
;
5624 v
->derive_adjustment
= 0;
5630 v
->auto_inc_opt
= 0;
5634 /* The v->always_computable field is used in update_giv_derive, to
5635 determine whether a giv can be used to derive another giv. For a
5636 DEST_REG giv, INSN computes a new value for the giv, so its value
5637 isn't computable if INSN insn't executed every iteration.
5638 However, for a DEST_ADDR giv, INSN merely uses the value of the giv;
5639 it does not compute a new value. Hence the value is always computable
5640 regardless of whether INSN is executed each iteration. */
5642 if (type
== DEST_ADDR
)
5643 v
->always_computable
= 1;
5645 v
->always_computable
= ! not_every_iteration
;
5647 v
->always_executed
= ! not_every_iteration
;
5649 if (type
== DEST_ADDR
)
5651 v
->mode
= GET_MODE (*location
);
5654 else /* type == DEST_REG */
5656 v
->mode
= GET_MODE (SET_DEST (set
));
5658 v
->lifetime
= LOOP_REG_LIFETIME (loop
, REGNO (dest_reg
));
5660 /* If the lifetime is zero, it means that this register is
5661 really a dead store. So mark this as a giv that can be
5662 ignored. This will not prevent the biv from being eliminated. */
5663 if (v
->lifetime
== 0)
5666 REG_IV_TYPE (ivs
, REGNO (dest_reg
)) = GENERAL_INDUCT
;
5667 REG_IV_INFO (ivs
, REGNO (dest_reg
)) = v
;
5670 /* Add the giv to the class of givs computed from one biv. */
5672 bl
= REG_IV_CLASS (ivs
, REGNO (src_reg
));
5675 v
->next_iv
= bl
->giv
;
5677 /* Don't count DEST_ADDR. This is supposed to count the number of
5678 insns that calculate givs. */
5679 if (type
== DEST_REG
)
5681 bl
->total_benefit
+= benefit
;
5684 /* Fatal error, biv missing for this giv? */
5687 if (type
== DEST_ADDR
)
5691 /* The giv can be replaced outright by the reduced register only if all
5692 of the following conditions are true:
5693 - the insn that sets the giv is always executed on any iteration
5694 on which the giv is used at all
5695 (there are two ways to deduce this:
5696 either the insn is executed on every iteration,
5697 or all uses follow that insn in the same basic block),
5698 - the giv is not used outside the loop
5699 - no assignments to the biv occur during the giv's lifetime. */
5701 if (REGNO_FIRST_UID (REGNO (dest_reg
)) == INSN_UID (insn
)
5702 /* Previous line always fails if INSN was moved by loop opt. */
5703 && REGNO_LAST_LUID (REGNO (dest_reg
))
5704 < INSN_LUID (loop
->end
)
5705 && (! not_every_iteration
5706 || last_use_this_basic_block (dest_reg
, insn
)))
5708 /* Now check that there are no assignments to the biv within the
5709 giv's lifetime. This requires two separate checks. */
5711 /* Check each biv update, and fail if any are between the first
5712 and last use of the giv.
5714 If this loop contains an inner loop that was unrolled, then
5715 the insn modifying the biv may have been emitted by the loop
5716 unrolling code, and hence does not have a valid luid. Just
5717 mark the biv as not replaceable in this case. It is not very
5718 useful as a biv, because it is used in two different loops.
5719 It is very unlikely that we would be able to optimize the giv
5720 using this biv anyways. */
5723 for (b
= bl
->biv
; b
; b
= b
->next_iv
)
5725 if (INSN_UID (b
->insn
) >= max_uid_for_loop
5726 || ((INSN_LUID (b
->insn
)
5727 >= REGNO_FIRST_LUID (REGNO (dest_reg
)))
5728 && (INSN_LUID (b
->insn
)
5729 <= REGNO_LAST_LUID (REGNO (dest_reg
)))))
5732 v
->not_replaceable
= 1;
5737 /* If there are any backwards branches that go from after the
5738 biv update to before it, then this giv is not replaceable. */
5740 for (b
= bl
->biv
; b
; b
= b
->next_iv
)
5741 if (back_branch_in_range_p (loop
, b
->insn
))
5744 v
->not_replaceable
= 1;
5750 /* May still be replaceable, we don't have enough info here to
5753 v
->not_replaceable
= 0;
5757 /* Record whether the add_val contains a const_int, for later use by
5762 v
->no_const_addval
= 1;
5763 if (tem
== const0_rtx
)
5765 else if (CONSTANT_P (add_val
))
5766 v
->no_const_addval
= 0;
5767 if (GET_CODE (tem
) == PLUS
)
5771 if (GET_CODE (XEXP (tem
, 0)) == PLUS
)
5772 tem
= XEXP (tem
, 0);
5773 else if (GET_CODE (XEXP (tem
, 1)) == PLUS
)
5774 tem
= XEXP (tem
, 1);
5778 if (CONSTANT_P (XEXP (tem
, 1)))
5779 v
->no_const_addval
= 0;
5783 if (loop_dump_stream
)
5784 loop_giv_dump (v
, loop_dump_stream
, 0);
5787 /* All this does is determine whether a giv can be made replaceable because
5788 its final value can be calculated. This code can not be part of record_giv
5789 above, because final_giv_value requires that the number of loop iterations
5790 be known, and that can not be accurately calculated until after all givs
5791 have been identified. */
5794 check_final_value (loop
, v
)
5795 const struct loop
*loop
;
5796 struct induction
*v
;
5798 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
5799 struct iv_class
*bl
;
5800 rtx final_value
= 0;
5802 bl
= REG_IV_CLASS (ivs
, REGNO (v
->src_reg
));
5804 /* DEST_ADDR givs will never reach here, because they are always marked
5805 replaceable above in record_giv. */
5807 /* The giv can be replaced outright by the reduced register only if all
5808 of the following conditions are true:
5809 - the insn that sets the giv is always executed on any iteration
5810 on which the giv is used at all
5811 (there are two ways to deduce this:
5812 either the insn is executed on every iteration,
5813 or all uses follow that insn in the same basic block),
5814 - its final value can be calculated (this condition is different
5815 than the one above in record_giv)
5816 - it's not used before the it's set
5817 - no assignments to the biv occur during the giv's lifetime. */
5820 /* This is only called now when replaceable is known to be false. */
5821 /* Clear replaceable, so that it won't confuse final_giv_value. */
5825 if ((final_value
= final_giv_value (loop
, v
))
5826 && (v
->always_computable
|| last_use_this_basic_block (v
->dest_reg
, v
->insn
)))
5828 int biv_increment_seen
= 0, before_giv_insn
= 0;
5834 /* When trying to determine whether or not a biv increment occurs
5835 during the lifetime of the giv, we can ignore uses of the variable
5836 outside the loop because final_value is true. Hence we can not
5837 use regno_last_uid and regno_first_uid as above in record_giv. */
5839 /* Search the loop to determine whether any assignments to the
5840 biv occur during the giv's lifetime. Start with the insn
5841 that sets the giv, and search around the loop until we come
5842 back to that insn again.
5844 Also fail if there is a jump within the giv's lifetime that jumps
5845 to somewhere outside the lifetime but still within the loop. This
5846 catches spaghetti code where the execution order is not linear, and
5847 hence the above test fails. Here we assume that the giv lifetime
5848 does not extend from one iteration of the loop to the next, so as
5849 to make the test easier. Since the lifetime isn't known yet,
5850 this requires two loops. See also record_giv above. */
5852 last_giv_use
= v
->insn
;
5859 before_giv_insn
= 1;
5860 p
= NEXT_INSN (loop
->start
);
5865 if (GET_CODE (p
) == INSN
|| GET_CODE (p
) == JUMP_INSN
5866 || GET_CODE (p
) == CALL_INSN
)
5868 /* It is possible for the BIV increment to use the GIV if we
5869 have a cycle. Thus we must be sure to check each insn for
5870 both BIV and GIV uses, and we must check for BIV uses
5873 if (! biv_increment_seen
5874 && reg_set_p (v
->src_reg
, PATTERN (p
)))
5875 biv_increment_seen
= 1;
5877 if (reg_mentioned_p (v
->dest_reg
, PATTERN (p
)))
5879 if (biv_increment_seen
|| before_giv_insn
)
5882 v
->not_replaceable
= 1;
5890 /* Now that the lifetime of the giv is known, check for branches
5891 from within the lifetime to outside the lifetime if it is still
5901 p
= NEXT_INSN (loop
->start
);
5902 if (p
== last_giv_use
)
5905 if (GET_CODE (p
) == JUMP_INSN
&& JUMP_LABEL (p
)
5906 && LABEL_NAME (JUMP_LABEL (p
))
5907 && ((loop_insn_first_p (JUMP_LABEL (p
), v
->insn
)
5908 && loop_insn_first_p (loop
->start
, JUMP_LABEL (p
)))
5909 || (loop_insn_first_p (last_giv_use
, JUMP_LABEL (p
))
5910 && loop_insn_first_p (JUMP_LABEL (p
), loop
->end
))))
5913 v
->not_replaceable
= 1;
5915 if (loop_dump_stream
)
5916 fprintf (loop_dump_stream
,
5917 "Found branch outside giv lifetime.\n");
5924 /* If it is replaceable, then save the final value. */
5926 v
->final_value
= final_value
;
5929 if (loop_dump_stream
&& v
->replaceable
)
5930 fprintf (loop_dump_stream
, "Insn %d: giv reg %d final_value replaceable\n",
5931 INSN_UID (v
->insn
), REGNO (v
->dest_reg
));
5934 /* Update the status of whether a giv can derive other givs.
5936 We need to do something special if there is or may be an update to the biv
5937 between the time the giv is defined and the time it is used to derive
5940 In addition, a giv that is only conditionally set is not allowed to
5941 derive another giv once a label has been passed.
5943 The cases we look at are when a label or an update to a biv is passed. */
5946 update_giv_derive (loop
, p
)
5947 const struct loop
*loop
;
5950 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
5951 struct iv_class
*bl
;
5952 struct induction
*biv
, *giv
;
5956 /* Search all IV classes, then all bivs, and finally all givs.
5958 There are three cases we are concerned with. First we have the situation
5959 of a giv that is only updated conditionally. In that case, it may not
5960 derive any givs after a label is passed.
5962 The second case is when a biv update occurs, or may occur, after the
5963 definition of a giv. For certain biv updates (see below) that are
5964 known to occur between the giv definition and use, we can adjust the
5965 giv definition. For others, or when the biv update is conditional,
5966 we must prevent the giv from deriving any other givs. There are two
5967 sub-cases within this case.
5969 If this is a label, we are concerned with any biv update that is done
5970 conditionally, since it may be done after the giv is defined followed by
5971 a branch here (actually, we need to pass both a jump and a label, but
5972 this extra tracking doesn't seem worth it).
5974 If this is a jump, we are concerned about any biv update that may be
5975 executed multiple times. We are actually only concerned about
5976 backward jumps, but it is probably not worth performing the test
5977 on the jump again here.
5979 If this is a biv update, we must adjust the giv status to show that a
5980 subsequent biv update was performed. If this adjustment cannot be done,
5981 the giv cannot derive further givs. */
5983 for (bl
= ivs
->list
; bl
; bl
= bl
->next
)
5984 for (biv
= bl
->biv
; biv
; biv
= biv
->next_iv
)
5985 if (GET_CODE (p
) == CODE_LABEL
|| GET_CODE (p
) == JUMP_INSN
5988 for (giv
= bl
->giv
; giv
; giv
= giv
->next_iv
)
5990 /* If cant_derive is already true, there is no point in
5991 checking all of these conditions again. */
5992 if (giv
->cant_derive
)
5995 /* If this giv is conditionally set and we have passed a label,
5996 it cannot derive anything. */
5997 if (GET_CODE (p
) == CODE_LABEL
&& ! giv
->always_computable
)
5998 giv
->cant_derive
= 1;
6000 /* Skip givs that have mult_val == 0, since
6001 they are really invariants. Also skip those that are
6002 replaceable, since we know their lifetime doesn't contain
6004 else if (giv
->mult_val
== const0_rtx
|| giv
->replaceable
)
6007 /* The only way we can allow this giv to derive another
6008 is if this is a biv increment and we can form the product
6009 of biv->add_val and giv->mult_val. In this case, we will
6010 be able to compute a compensation. */
6011 else if (biv
->insn
== p
)
6016 if (biv
->mult_val
== const1_rtx
)
6017 tem
= simplify_giv_expr (loop
,
6018 gen_rtx_MULT (giv
->mode
,
6021 &ext_val_dummy
, &dummy
);
6023 if (tem
&& giv
->derive_adjustment
)
6024 tem
= simplify_giv_expr
6026 gen_rtx_PLUS (giv
->mode
, tem
, giv
->derive_adjustment
),
6027 &ext_val_dummy
, &dummy
);
6030 giv
->derive_adjustment
= tem
;
6032 giv
->cant_derive
= 1;
6034 else if ((GET_CODE (p
) == CODE_LABEL
&& ! biv
->always_computable
)
6035 || (GET_CODE (p
) == JUMP_INSN
&& biv
->maybe_multiple
))
6036 giv
->cant_derive
= 1;
6041 /* Check whether an insn is an increment legitimate for a basic induction var.
6042 X is the source of insn P, or a part of it.
6043 MODE is the mode in which X should be interpreted.
6045 DEST_REG is the putative biv, also the destination of the insn.
6046 We accept patterns of these forms:
6047 REG = REG + INVARIANT (includes REG = REG - CONSTANT)
6048 REG = INVARIANT + REG
6050 If X is suitable, we return 1, set *MULT_VAL to CONST1_RTX,
6051 store the additive term into *INC_VAL, and store the place where
6052 we found the additive term into *LOCATION.
6054 If X is an assignment of an invariant into DEST_REG, we set
6055 *MULT_VAL to CONST0_RTX, and store the invariant into *INC_VAL.
6057 We also want to detect a BIV when it corresponds to a variable
6058 whose mode was promoted via PROMOTED_MODE. In that case, an increment
6059 of the variable may be a PLUS that adds a SUBREG of that variable to
6060 an invariant and then sign- or zero-extends the result of the PLUS
6063 Most GIVs in such cases will be in the promoted mode, since that is the
6064 probably the natural computation mode (and almost certainly the mode
6065 used for addresses) on the machine. So we view the pseudo-reg containing
6066 the variable as the BIV, as if it were simply incremented.
6068 Note that treating the entire pseudo as a BIV will result in making
6069 simple increments to any GIVs based on it. However, if the variable
6070 overflows in its declared mode but not its promoted mode, the result will
6071 be incorrect. This is acceptable if the variable is signed, since
6072 overflows in such cases are undefined, but not if it is unsigned, since
6073 those overflows are defined. So we only check for SIGN_EXTEND and
6076 If we cannot find a biv, we return 0. */
6079 basic_induction_var (loop
, x
, mode
, dest_reg
, p
, inc_val
, mult_val
, location
)
6080 const struct loop
*loop
;
6082 enum machine_mode mode
;
6093 code
= GET_CODE (x
);
6098 if (rtx_equal_p (XEXP (x
, 0), dest_reg
)
6099 || (GET_CODE (XEXP (x
, 0)) == SUBREG
6100 && SUBREG_PROMOTED_VAR_P (XEXP (x
, 0))
6101 && SUBREG_REG (XEXP (x
, 0)) == dest_reg
))
6103 argp
= &XEXP (x
, 1);
6105 else if (rtx_equal_p (XEXP (x
, 1), dest_reg
)
6106 || (GET_CODE (XEXP (x
, 1)) == SUBREG
6107 && SUBREG_PROMOTED_VAR_P (XEXP (x
, 1))
6108 && SUBREG_REG (XEXP (x
, 1)) == dest_reg
))
6110 argp
= &XEXP (x
, 0);
6116 if (loop_invariant_p (loop
, arg
) != 1)
6119 *inc_val
= convert_modes (GET_MODE (dest_reg
), GET_MODE (x
), arg
, 0);
6120 *mult_val
= const1_rtx
;
6125 /* If this is a SUBREG for a promoted variable, check the inner
6127 if (SUBREG_PROMOTED_VAR_P (x
))
6128 return basic_induction_var (loop
, SUBREG_REG (x
),
6129 GET_MODE (SUBREG_REG (x
)),
6130 dest_reg
, p
, inc_val
, mult_val
, location
);
6134 /* If this register is assigned in a previous insn, look at its
6135 source, but don't go outside the loop or past a label. */
6137 /* If this sets a register to itself, we would repeat any previous
6138 biv increment if we applied this strategy blindly. */
6139 if (rtx_equal_p (dest_reg
, x
))
6148 insn
= PREV_INSN (insn
);
6150 while (insn
&& GET_CODE (insn
) == NOTE
6151 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_BEG
);
6155 set
= single_set (insn
);
6158 dest
= SET_DEST (set
);
6160 || (GET_CODE (dest
) == SUBREG
6161 && (GET_MODE_SIZE (GET_MODE (dest
)) <= UNITS_PER_WORD
)
6162 && (GET_MODE_CLASS (GET_MODE (dest
)) == MODE_INT
)
6163 && SUBREG_REG (dest
) == x
))
6164 return basic_induction_var (loop
, SET_SRC (set
),
6165 (GET_MODE (SET_SRC (set
)) == VOIDmode
6167 : GET_MODE (SET_SRC (set
))),
6169 inc_val
, mult_val
, location
);
6171 while (GET_CODE (dest
) == SIGN_EXTRACT
6172 || GET_CODE (dest
) == ZERO_EXTRACT
6173 || GET_CODE (dest
) == SUBREG
6174 || GET_CODE (dest
) == STRICT_LOW_PART
)
6175 dest
= XEXP (dest
, 0);
6181 /* Can accept constant setting of biv only when inside inner most loop.
6182 Otherwise, a biv of an inner loop may be incorrectly recognized
6183 as a biv of the outer loop,
6184 causing code to be moved INTO the inner loop. */
6186 if (loop_invariant_p (loop
, x
) != 1)
6191 /* convert_modes aborts if we try to convert to or from CCmode, so just
6192 exclude that case. It is very unlikely that a condition code value
6193 would be a useful iterator anyways. */
6194 if (loop
->level
== 1
6195 && GET_MODE_CLASS (mode
) != MODE_CC
6196 && GET_MODE_CLASS (GET_MODE (dest_reg
)) != MODE_CC
)
6198 /* Possible bug here? Perhaps we don't know the mode of X. */
6199 *inc_val
= convert_modes (GET_MODE (dest_reg
), mode
, x
, 0);
6200 *mult_val
= const0_rtx
;
6207 return basic_induction_var (loop
, XEXP (x
, 0), GET_MODE (XEXP (x
, 0)),
6208 dest_reg
, p
, inc_val
, mult_val
, location
);
6211 /* Similar, since this can be a sign extension. */
6212 for (insn
= PREV_INSN (p
);
6213 (insn
&& GET_CODE (insn
) == NOTE
6214 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_BEG
);
6215 insn
= PREV_INSN (insn
))
6219 set
= single_set (insn
);
6221 if (! rtx_equal_p (dest_reg
, XEXP (x
, 0))
6222 && set
&& SET_DEST (set
) == XEXP (x
, 0)
6223 && GET_CODE (XEXP (x
, 1)) == CONST_INT
6224 && INTVAL (XEXP (x
, 1)) >= 0
6225 && GET_CODE (SET_SRC (set
)) == ASHIFT
6226 && XEXP (x
, 1) == XEXP (SET_SRC (set
), 1))
6227 return basic_induction_var (loop
, XEXP (SET_SRC (set
), 0),
6228 GET_MODE (XEXP (x
, 0)),
6229 dest_reg
, insn
, inc_val
, mult_val
,
6238 /* A general induction variable (giv) is any quantity that is a linear
6239 function of a basic induction variable,
6240 i.e. giv = biv * mult_val + add_val.
6241 The coefficients can be any loop invariant quantity.
6242 A giv need not be computed directly from the biv;
6243 it can be computed by way of other givs. */
6245 /* Determine whether X computes a giv.
6246 If it does, return a nonzero value
6247 which is the benefit from eliminating the computation of X;
6248 set *SRC_REG to the register of the biv that it is computed from;
6249 set *ADD_VAL and *MULT_VAL to the coefficients,
6250 such that the value of X is biv * mult + add; */
6253 general_induction_var (loop
, x
, src_reg
, add_val
, mult_val
, ext_val
,
6254 is_addr
, pbenefit
, addr_mode
)
6255 const struct loop
*loop
;
6263 enum machine_mode addr_mode
;
6265 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
6268 /* If this is an invariant, forget it, it isn't a giv. */
6269 if (loop_invariant_p (loop
, x
) == 1)
6273 *ext_val
= NULL_RTX
;
6274 x
= simplify_giv_expr (loop
, x
, ext_val
, pbenefit
);
6278 switch (GET_CODE (x
))
6282 /* Since this is now an invariant and wasn't before, it must be a giv
6283 with MULT_VAL == 0. It doesn't matter which BIV we associate this
6285 *src_reg
= ivs
->list
->biv
->dest_reg
;
6286 *mult_val
= const0_rtx
;
6291 /* This is equivalent to a BIV. */
6293 *mult_val
= const1_rtx
;
6294 *add_val
= const0_rtx
;
6298 /* Either (plus (biv) (invar)) or
6299 (plus (mult (biv) (invar_1)) (invar_2)). */
6300 if (GET_CODE (XEXP (x
, 0)) == MULT
)
6302 *src_reg
= XEXP (XEXP (x
, 0), 0);
6303 *mult_val
= XEXP (XEXP (x
, 0), 1);
6307 *src_reg
= XEXP (x
, 0);
6308 *mult_val
= const1_rtx
;
6310 *add_val
= XEXP (x
, 1);
6314 /* ADD_VAL is zero. */
6315 *src_reg
= XEXP (x
, 0);
6316 *mult_val
= XEXP (x
, 1);
6317 *add_val
= const0_rtx
;
6324 /* Remove any enclosing USE from ADD_VAL and MULT_VAL (there will be
6325 unless they are CONST_INT). */
6326 if (GET_CODE (*add_val
) == USE
)
6327 *add_val
= XEXP (*add_val
, 0);
6328 if (GET_CODE (*mult_val
) == USE
)
6329 *mult_val
= XEXP (*mult_val
, 0);
6332 *pbenefit
+= address_cost (orig_x
, addr_mode
) - reg_address_cost
;
6334 *pbenefit
+= rtx_cost (orig_x
, SET
);
6336 /* Always return true if this is a giv so it will be detected as such,
6337 even if the benefit is zero or negative. This allows elimination
6338 of bivs that might otherwise not be eliminated. */
6342 /* Given an expression, X, try to form it as a linear function of a biv.
6343 We will canonicalize it to be of the form
6344 (plus (mult (BIV) (invar_1))
6346 with possible degeneracies.
6348 The invariant expressions must each be of a form that can be used as a
6349 machine operand. We surround then with a USE rtx (a hack, but localized
6350 and certainly unambiguous!) if not a CONST_INT for simplicity in this
6351 routine; it is the caller's responsibility to strip them.
6353 If no such canonicalization is possible (i.e., two biv's are used or an
6354 expression that is neither invariant nor a biv or giv), this routine
6357 For a non-zero return, the result will have a code of CONST_INT, USE,
6358 REG (for a BIV), PLUS, or MULT. No other codes will occur.
6360 *BENEFIT will be incremented by the benefit of any sub-giv encountered. */
6362 static rtx sge_plus
PARAMS ((enum machine_mode
, rtx
, rtx
));
6363 static rtx sge_plus_constant
PARAMS ((rtx
, rtx
));
6366 simplify_giv_expr (loop
, x
, ext_val
, benefit
)
6367 const struct loop
*loop
;
6372 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
6373 struct loop_regs
*regs
= LOOP_REGS (loop
);
6374 enum machine_mode mode
= GET_MODE (x
);
6378 /* If this is not an integer mode, or if we cannot do arithmetic in this
6379 mode, this can't be a giv. */
6380 if (mode
!= VOIDmode
6381 && (GET_MODE_CLASS (mode
) != MODE_INT
6382 || GET_MODE_BITSIZE (mode
) > HOST_BITS_PER_WIDE_INT
))
6385 switch (GET_CODE (x
))
6388 arg0
= simplify_giv_expr (loop
, XEXP (x
, 0), ext_val
, benefit
);
6389 arg1
= simplify_giv_expr (loop
, XEXP (x
, 1), ext_val
, benefit
);
6390 if (arg0
== 0 || arg1
== 0)
6393 /* Put constant last, CONST_INT last if both constant. */
6394 if ((GET_CODE (arg0
) == USE
6395 || GET_CODE (arg0
) == CONST_INT
)
6396 && ! ((GET_CODE (arg0
) == USE
6397 && GET_CODE (arg1
) == USE
)
6398 || GET_CODE (arg1
) == CONST_INT
))
6399 tem
= arg0
, arg0
= arg1
, arg1
= tem
;
6401 /* Handle addition of zero, then addition of an invariant. */
6402 if (arg1
== const0_rtx
)
6404 else if (GET_CODE (arg1
) == CONST_INT
|| GET_CODE (arg1
) == USE
)
6405 switch (GET_CODE (arg0
))
6409 /* Adding two invariants must result in an invariant, so enclose
6410 addition operation inside a USE and return it. */
6411 if (GET_CODE (arg0
) == USE
)
6412 arg0
= XEXP (arg0
, 0);
6413 if (GET_CODE (arg1
) == USE
)
6414 arg1
= XEXP (arg1
, 0);
6416 if (GET_CODE (arg0
) == CONST_INT
)
6417 tem
= arg0
, arg0
= arg1
, arg1
= tem
;
6418 if (GET_CODE (arg1
) == CONST_INT
)
6419 tem
= sge_plus_constant (arg0
, arg1
);
6421 tem
= sge_plus (mode
, arg0
, arg1
);
6423 if (GET_CODE (tem
) != CONST_INT
)
6424 tem
= gen_rtx_USE (mode
, tem
);
6429 /* biv + invar or mult + invar. Return sum. */
6430 return gen_rtx_PLUS (mode
, arg0
, arg1
);
6433 /* (a + invar_1) + invar_2. Associate. */
6435 simplify_giv_expr (loop
,
6447 /* Each argument must be either REG, PLUS, or MULT. Convert REG to
6448 MULT to reduce cases. */
6449 if (GET_CODE (arg0
) == REG
)
6450 arg0
= gen_rtx_MULT (mode
, arg0
, const1_rtx
);
6451 if (GET_CODE (arg1
) == REG
)
6452 arg1
= gen_rtx_MULT (mode
, arg1
, const1_rtx
);
6454 /* Now have PLUS + PLUS, PLUS + MULT, MULT + PLUS, or MULT + MULT.
6455 Put a MULT first, leaving PLUS + PLUS, MULT + PLUS, or MULT + MULT.
6456 Recurse to associate the second PLUS. */
6457 if (GET_CODE (arg1
) == MULT
)
6458 tem
= arg0
, arg0
= arg1
, arg1
= tem
;
6460 if (GET_CODE (arg1
) == PLUS
)
6462 simplify_giv_expr (loop
,
6464 gen_rtx_PLUS (mode
, arg0
,
6469 /* Now must have MULT + MULT. Distribute if same biv, else not giv. */
6470 if (GET_CODE (arg0
) != MULT
|| GET_CODE (arg1
) != MULT
)
6473 if (!rtx_equal_p (arg0
, arg1
))
6476 return simplify_giv_expr (loop
,
6485 /* Handle "a - b" as "a + b * (-1)". */
6486 return simplify_giv_expr (loop
,
6495 arg0
= simplify_giv_expr (loop
, XEXP (x
, 0), ext_val
, benefit
);
6496 arg1
= simplify_giv_expr (loop
, XEXP (x
, 1), ext_val
, benefit
);
6497 if (arg0
== 0 || arg1
== 0)
6500 /* Put constant last, CONST_INT last if both constant. */
6501 if ((GET_CODE (arg0
) == USE
|| GET_CODE (arg0
) == CONST_INT
)
6502 && GET_CODE (arg1
) != CONST_INT
)
6503 tem
= arg0
, arg0
= arg1
, arg1
= tem
;
6505 /* If second argument is not now constant, not giv. */
6506 if (GET_CODE (arg1
) != USE
&& GET_CODE (arg1
) != CONST_INT
)
6509 /* Handle multiply by 0 or 1. */
6510 if (arg1
== const0_rtx
)
6513 else if (arg1
== const1_rtx
)
6516 switch (GET_CODE (arg0
))
6519 /* biv * invar. Done. */
6520 return gen_rtx_MULT (mode
, arg0
, arg1
);
6523 /* Product of two constants. */
6524 return GEN_INT (INTVAL (arg0
) * INTVAL (arg1
));
6527 /* invar * invar is a giv, but attempt to simplify it somehow. */
6528 if (GET_CODE (arg1
) != CONST_INT
)
6531 arg0
= XEXP (arg0
, 0);
6532 if (GET_CODE (arg0
) == MULT
)
6534 /* (invar_0 * invar_1) * invar_2. Associate. */
6535 return simplify_giv_expr (loop
,
6544 /* Porpagate the MULT expressions to the intermost nodes. */
6545 else if (GET_CODE (arg0
) == PLUS
)
6547 /* (invar_0 + invar_1) * invar_2. Distribute. */
6548 return simplify_giv_expr (loop
,
6560 return gen_rtx_USE (mode
, gen_rtx_MULT (mode
, arg0
, arg1
));
6563 /* (a * invar_1) * invar_2. Associate. */
6564 return simplify_giv_expr (loop
,
6573 /* (a + invar_1) * invar_2. Distribute. */
6574 return simplify_giv_expr (loop
,
6589 /* Shift by constant is multiply by power of two. */
6590 if (GET_CODE (XEXP (x
, 1)) != CONST_INT
)
6594 simplify_giv_expr (loop
,
6597 GEN_INT ((HOST_WIDE_INT
) 1
6598 << INTVAL (XEXP (x
, 1)))),
6602 /* "-a" is "a * (-1)" */
6603 return simplify_giv_expr (loop
,
6604 gen_rtx_MULT (mode
, XEXP (x
, 0), constm1_rtx
),
6608 /* "~a" is "-a - 1". Silly, but easy. */
6609 return simplify_giv_expr (loop
,
6610 gen_rtx_MINUS (mode
,
6611 gen_rtx_NEG (mode
, XEXP (x
, 0)),
6616 /* Already in proper form for invariant. */
6622 /* Conditionally recognize extensions of simple IVs. After we've
6623 computed loop traversal counts and verified the range of the
6624 source IV, we'll reevaluate this as a GIV. */
6625 if (*ext_val
== NULL_RTX
)
6627 arg0
= simplify_giv_expr (loop
, XEXP (x
, 0), ext_val
, benefit
);
6628 if (arg0
&& *ext_val
== NULL_RTX
&& GET_CODE (arg0
) == REG
)
6630 *ext_val
= gen_rtx_fmt_e (GET_CODE (x
), mode
, arg0
);
6637 /* If this is a new register, we can't deal with it. */
6638 if (REGNO (x
) >= max_reg_before_loop
)
6641 /* Check for biv or giv. */
6642 switch (REG_IV_TYPE (ivs
, REGNO (x
)))
6646 case GENERAL_INDUCT
:
6648 struct induction
*v
= REG_IV_INFO (ivs
, REGNO (x
));
6650 /* Form expression from giv and add benefit. Ensure this giv
6651 can derive another and subtract any needed adjustment if so. */
6653 /* Increasing the benefit here is risky. The only case in which it
6654 is arguably correct is if this is the only use of V. In other
6655 cases, this will artificially inflate the benefit of the current
6656 giv, and lead to suboptimal code. Thus, it is disabled, since
6657 potentially not reducing an only marginally beneficial giv is
6658 less harmful than reducing many givs that are not really
6661 rtx single_use
= regs
->array
[REGNO (x
)].single_usage
;
6662 if (single_use
&& single_use
!= const0_rtx
)
6663 *benefit
+= v
->benefit
;
6669 tem
= gen_rtx_PLUS (mode
, gen_rtx_MULT (mode
,
6670 v
->src_reg
, v
->mult_val
),
6673 if (v
->derive_adjustment
)
6674 tem
= gen_rtx_MINUS (mode
, tem
, v
->derive_adjustment
);
6675 arg0
= simplify_giv_expr (loop
, tem
, ext_val
, benefit
);
6678 if (!v
->ext_dependent
)
6683 *ext_val
= v
->ext_dependent
;
6691 /* If it isn't an induction variable, and it is invariant, we
6692 may be able to simplify things further by looking through
6693 the bits we just moved outside the loop. */
6694 if (loop_invariant_p (loop
, x
) == 1)
6697 struct loop_movables
*movables
= LOOP_MOVABLES (loop
);
6699 for (m
= movables
->head
; m
; m
= m
->next
)
6700 if (rtx_equal_p (x
, m
->set_dest
))
6702 /* Ok, we found a match. Substitute and simplify. */
6704 /* If we match another movable, we must use that, as
6705 this one is going away. */
6707 return simplify_giv_expr (loop
, m
->match
->set_dest
,
6710 /* If consec is non-zero, this is a member of a group of
6711 instructions that were moved together. We handle this
6712 case only to the point of seeking to the last insn and
6713 looking for a REG_EQUAL. Fail if we don't find one. */
6720 tem
= NEXT_INSN (tem
);
6724 tem
= find_reg_note (tem
, REG_EQUAL
, NULL_RTX
);
6726 tem
= XEXP (tem
, 0);
6730 tem
= single_set (m
->insn
);
6732 tem
= SET_SRC (tem
);
6737 /* What we are most interested in is pointer
6738 arithmetic on invariants -- only take
6739 patterns we may be able to do something with. */
6740 if (GET_CODE (tem
) == PLUS
6741 || GET_CODE (tem
) == MULT
6742 || GET_CODE (tem
) == ASHIFT
6743 || GET_CODE (tem
) == CONST_INT
6744 || GET_CODE (tem
) == SYMBOL_REF
)
6746 tem
= simplify_giv_expr (loop
, tem
, ext_val
,
6751 else if (GET_CODE (tem
) == CONST
6752 && GET_CODE (XEXP (tem
, 0)) == PLUS
6753 && GET_CODE (XEXP (XEXP (tem
, 0), 0)) == SYMBOL_REF
6754 && GET_CODE (XEXP (XEXP (tem
, 0), 1)) == CONST_INT
)
6756 tem
= simplify_giv_expr (loop
, XEXP (tem
, 0),
6768 /* Fall through to general case. */
6770 /* If invariant, return as USE (unless CONST_INT).
6771 Otherwise, not giv. */
6772 if (GET_CODE (x
) == USE
)
6775 if (loop_invariant_p (loop
, x
) == 1)
6777 if (GET_CODE (x
) == CONST_INT
)
6779 if (GET_CODE (x
) == CONST
6780 && GET_CODE (XEXP (x
, 0)) == PLUS
6781 && GET_CODE (XEXP (XEXP (x
, 0), 0)) == SYMBOL_REF
6782 && GET_CODE (XEXP (XEXP (x
, 0), 1)) == CONST_INT
)
6784 return gen_rtx_USE (mode
, x
);
6791 /* This routine folds invariants such that there is only ever one
6792 CONST_INT in the summation. It is only used by simplify_giv_expr. */
6795 sge_plus_constant (x
, c
)
6798 if (GET_CODE (x
) == CONST_INT
)
6799 return GEN_INT (INTVAL (x
) + INTVAL (c
));
6800 else if (GET_CODE (x
) != PLUS
)
6801 return gen_rtx_PLUS (GET_MODE (x
), x
, c
);
6802 else if (GET_CODE (XEXP (x
, 1)) == CONST_INT
)
6804 return gen_rtx_PLUS (GET_MODE (x
), XEXP (x
, 0),
6805 GEN_INT (INTVAL (XEXP (x
, 1)) + INTVAL (c
)));
6807 else if (GET_CODE (XEXP (x
, 0)) == PLUS
6808 || GET_CODE (XEXP (x
, 1)) != PLUS
)
6810 return gen_rtx_PLUS (GET_MODE (x
),
6811 sge_plus_constant (XEXP (x
, 0), c
), XEXP (x
, 1));
6815 return gen_rtx_PLUS (GET_MODE (x
),
6816 sge_plus_constant (XEXP (x
, 1), c
), XEXP (x
, 0));
6821 sge_plus (mode
, x
, y
)
6822 enum machine_mode mode
;
6825 while (GET_CODE (y
) == PLUS
)
6827 rtx a
= XEXP (y
, 0);
6828 if (GET_CODE (a
) == CONST_INT
)
6829 x
= sge_plus_constant (x
, a
);
6831 x
= gen_rtx_PLUS (mode
, x
, a
);
6834 if (GET_CODE (y
) == CONST_INT
)
6835 x
= sge_plus_constant (x
, y
);
6837 x
= gen_rtx_PLUS (mode
, x
, y
);
6841 /* Help detect a giv that is calculated by several consecutive insns;
6845 The caller has already identified the first insn P as having a giv as dest;
6846 we check that all other insns that set the same register follow
6847 immediately after P, that they alter nothing else,
6848 and that the result of the last is still a giv.
6850 The value is 0 if the reg set in P is not really a giv.
6851 Otherwise, the value is the amount gained by eliminating
6852 all the consecutive insns that compute the value.
6854 FIRST_BENEFIT is the amount gained by eliminating the first insn, P.
6855 SRC_REG is the reg of the biv; DEST_REG is the reg of the giv.
6857 The coefficients of the ultimate giv value are stored in
6858 *MULT_VAL and *ADD_VAL. */
6861 consec_sets_giv (loop
, first_benefit
, p
, src_reg
, dest_reg
,
6862 add_val
, mult_val
, ext_val
, last_consec_insn
)
6863 const struct loop
*loop
;
6871 rtx
*last_consec_insn
;
6873 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
6874 struct loop_regs
*regs
= LOOP_REGS (loop
);
6881 /* Indicate that this is a giv so that we can update the value produced in
6882 each insn of the multi-insn sequence.
6884 This induction structure will be used only by the call to
6885 general_induction_var below, so we can allocate it on our stack.
6886 If this is a giv, our caller will replace the induct var entry with
6887 a new induction structure. */
6888 struct induction
*v
;
6890 if (REG_IV_TYPE (ivs
, REGNO (dest_reg
)) != UNKNOWN_INDUCT
)
6893 v
= (struct induction
*) alloca (sizeof (struct induction
));
6894 v
->src_reg
= src_reg
;
6895 v
->mult_val
= *mult_val
;
6896 v
->add_val
= *add_val
;
6897 v
->benefit
= first_benefit
;
6899 v
->derive_adjustment
= 0;
6900 v
->ext_dependent
= NULL_RTX
;
6902 REG_IV_TYPE (ivs
, REGNO (dest_reg
)) = GENERAL_INDUCT
;
6903 REG_IV_INFO (ivs
, REGNO (dest_reg
)) = v
;
6905 count
= regs
->array
[REGNO (dest_reg
)].n_times_set
- 1;
6910 code
= GET_CODE (p
);
6912 /* If libcall, skip to end of call sequence. */
6913 if (code
== INSN
&& (temp
= find_reg_note (p
, REG_LIBCALL
, NULL_RTX
)))
6917 && (set
= single_set (p
))
6918 && GET_CODE (SET_DEST (set
)) == REG
6919 && SET_DEST (set
) == dest_reg
6920 && (general_induction_var (loop
, SET_SRC (set
), &src_reg
,
6921 add_val
, mult_val
, ext_val
, 0,
6923 /* Giv created by equivalent expression. */
6924 || ((temp
= find_reg_note (p
, REG_EQUAL
, NULL_RTX
))
6925 && general_induction_var (loop
, XEXP (temp
, 0), &src_reg
,
6926 add_val
, mult_val
, ext_val
, 0,
6927 &benefit
, VOIDmode
)))
6928 && src_reg
== v
->src_reg
)
6930 if (find_reg_note (p
, REG_RETVAL
, NULL_RTX
))
6931 benefit
+= libcall_benefit (p
);
6934 v
->mult_val
= *mult_val
;
6935 v
->add_val
= *add_val
;
6936 v
->benefit
+= benefit
;
6938 else if (code
!= NOTE
)
6940 /* Allow insns that set something other than this giv to a
6941 constant. Such insns are needed on machines which cannot
6942 include long constants and should not disqualify a giv. */
6944 && (set
= single_set (p
))
6945 && SET_DEST (set
) != dest_reg
6946 && CONSTANT_P (SET_SRC (set
)))
6949 REG_IV_TYPE (ivs
, REGNO (dest_reg
)) = UNKNOWN_INDUCT
;
6954 REG_IV_TYPE (ivs
, REGNO (dest_reg
)) = UNKNOWN_INDUCT
;
6955 *last_consec_insn
= p
;
6959 /* Return an rtx, if any, that expresses giv G2 as a function of the register
6960 represented by G1. If no such expression can be found, or it is clear that
6961 it cannot possibly be a valid address, 0 is returned.
6963 To perform the computation, we note that
6966 where `v' is the biv.
6968 So G2 = (y/b) * G1 + (b - a*y/x).
6970 Note that MULT = y/x.
6972 Update: A and B are now allowed to be additive expressions such that
6973 B contains all variables in A. That is, computing B-A will not require
6974 subtracting variables. */
6977 express_from_1 (a
, b
, mult
)
6980 /* If MULT is zero, then A*MULT is zero, and our expression is B. */
6982 if (mult
== const0_rtx
)
6985 /* If MULT is not 1, we cannot handle A with non-constants, since we
6986 would then be required to subtract multiples of the registers in A.
6987 This is theoretically possible, and may even apply to some Fortran
6988 constructs, but it is a lot of work and we do not attempt it here. */
6990 if (mult
!= const1_rtx
&& GET_CODE (a
) != CONST_INT
)
6993 /* In general these structures are sorted top to bottom (down the PLUS
6994 chain), but not left to right across the PLUS. If B is a higher
6995 order giv than A, we can strip one level and recurse. If A is higher
6996 order, we'll eventually bail out, but won't know that until the end.
6997 If they are the same, we'll strip one level around this loop. */
6999 while (GET_CODE (a
) == PLUS
&& GET_CODE (b
) == PLUS
)
7001 rtx ra
, rb
, oa
, ob
, tmp
;
7003 ra
= XEXP (a
, 0), oa
= XEXP (a
, 1);
7004 if (GET_CODE (ra
) == PLUS
)
7005 tmp
= ra
, ra
= oa
, oa
= tmp
;
7007 rb
= XEXP (b
, 0), ob
= XEXP (b
, 1);
7008 if (GET_CODE (rb
) == PLUS
)
7009 tmp
= rb
, rb
= ob
, ob
= tmp
;
7011 if (rtx_equal_p (ra
, rb
))
7012 /* We matched: remove one reg completely. */
7014 else if (GET_CODE (ob
) != PLUS
&& rtx_equal_p (ra
, ob
))
7015 /* An alternate match. */
7017 else if (GET_CODE (oa
) != PLUS
&& rtx_equal_p (oa
, rb
))
7018 /* An alternate match. */
7022 /* Indicates an extra register in B. Strip one level from B and
7023 recurse, hoping B was the higher order expression. */
7024 ob
= express_from_1 (a
, ob
, mult
);
7027 return gen_rtx_PLUS (GET_MODE (b
), rb
, ob
);
7031 /* Here we are at the last level of A, go through the cases hoping to
7032 get rid of everything but a constant. */
7034 if (GET_CODE (a
) == PLUS
)
7038 ra
= XEXP (a
, 0), oa
= XEXP (a
, 1);
7039 if (rtx_equal_p (oa
, b
))
7041 else if (!rtx_equal_p (ra
, b
))
7044 if (GET_CODE (oa
) != CONST_INT
)
7047 return GEN_INT (-INTVAL (oa
) * INTVAL (mult
));
7049 else if (GET_CODE (a
) == CONST_INT
)
7051 return plus_constant (b
, -INTVAL (a
) * INTVAL (mult
));
7053 else if (CONSTANT_P (a
))
7055 enum machine_mode mode_a
= GET_MODE (a
);
7056 enum machine_mode mode_b
= GET_MODE (b
);
7057 enum machine_mode mode
= mode_b
== VOIDmode
? mode_a
: mode_b
;
7058 return simplify_gen_binary (MINUS
, mode
, b
, a
);
7060 else if (GET_CODE (b
) == PLUS
)
7062 if (rtx_equal_p (a
, XEXP (b
, 0)))
7064 else if (rtx_equal_p (a
, XEXP (b
, 1)))
7069 else if (rtx_equal_p (a
, b
))
7076 express_from (g1
, g2
)
7077 struct induction
*g1
, *g2
;
7081 /* The value that G1 will be multiplied by must be a constant integer. Also,
7082 the only chance we have of getting a valid address is if b*c/a (see above
7083 for notation) is also an integer. */
7084 if (GET_CODE (g1
->mult_val
) == CONST_INT
7085 && GET_CODE (g2
->mult_val
) == CONST_INT
)
7087 if (g1
->mult_val
== const0_rtx
7088 || INTVAL (g2
->mult_val
) % INTVAL (g1
->mult_val
) != 0)
7090 mult
= GEN_INT (INTVAL (g2
->mult_val
) / INTVAL (g1
->mult_val
));
7092 else if (rtx_equal_p (g1
->mult_val
, g2
->mult_val
))
7096 /* ??? Find out if the one is a multiple of the other? */
7100 add
= express_from_1 (g1
->add_val
, g2
->add_val
, mult
);
7101 if (add
== NULL_RTX
)
7103 /* Failed. If we've got a multiplication factor between G1 and G2,
7104 scale G1's addend and try again. */
7105 if (INTVAL (mult
) > 1)
7107 rtx g1_add_val
= g1
->add_val
;
7108 if (GET_CODE (g1_add_val
) == MULT
7109 && GET_CODE (XEXP (g1_add_val
, 1)) == CONST_INT
)
7112 m
= INTVAL (mult
) * INTVAL (XEXP (g1_add_val
, 1));
7113 g1_add_val
= gen_rtx_MULT (GET_MODE (g1_add_val
),
7114 XEXP (g1_add_val
, 0), GEN_INT (m
));
7118 g1_add_val
= gen_rtx_MULT (GET_MODE (g1_add_val
), g1_add_val
,
7122 add
= express_from_1 (g1_add_val
, g2
->add_val
, const1_rtx
);
7125 if (add
== NULL_RTX
)
7128 /* Form simplified final result. */
7129 if (mult
== const0_rtx
)
7131 else if (mult
== const1_rtx
)
7132 mult
= g1
->dest_reg
;
7134 mult
= gen_rtx_MULT (g2
->mode
, g1
->dest_reg
, mult
);
7136 if (add
== const0_rtx
)
7140 if (GET_CODE (add
) == PLUS
7141 && CONSTANT_P (XEXP (add
, 1)))
7143 rtx tem
= XEXP (add
, 1);
7144 mult
= gen_rtx_PLUS (g2
->mode
, mult
, XEXP (add
, 0));
7148 return gen_rtx_PLUS (g2
->mode
, mult
, add
);
7152 /* Return an rtx, if any, that expresses giv G2 as a function of the register
7153 represented by G1. This indicates that G2 should be combined with G1 and
7154 that G2 can use (either directly or via an address expression) a register
7155 used to represent G1. */
7158 combine_givs_p (g1
, g2
)
7159 struct induction
*g1
, *g2
;
7163 /* With the introduction of ext dependent givs, we must care for modes.
7164 G2 must not use a wider mode than G1. */
7165 if (GET_MODE_SIZE (g1
->mode
) < GET_MODE_SIZE (g2
->mode
))
7168 ret
= comb
= express_from (g1
, g2
);
7169 if (comb
== NULL_RTX
)
7171 if (g1
->mode
!= g2
->mode
)
7172 ret
= gen_lowpart (g2
->mode
, comb
);
7174 /* If these givs are identical, they can be combined. We use the results
7175 of express_from because the addends are not in a canonical form, so
7176 rtx_equal_p is a weaker test. */
7177 /* But don't combine a DEST_REG giv with a DEST_ADDR giv; we want the
7178 combination to be the other way round. */
7179 if (comb
== g1
->dest_reg
7180 && (g1
->giv_type
== DEST_REG
|| g2
->giv_type
== DEST_ADDR
))
7185 /* If G2 can be expressed as a function of G1 and that function is valid
7186 as an address and no more expensive than using a register for G2,
7187 the expression of G2 in terms of G1 can be used. */
7189 && g2
->giv_type
== DEST_ADDR
7190 && memory_address_p (GET_MODE (g2
->mem
), ret
)
7191 /* ??? Looses, especially with -fforce-addr, where *g2->location
7192 will always be a register, and so anything more complicated
7196 && ADDRESS_COST (tem
) <= ADDRESS_COST (*g2
->location
)
7198 && rtx_cost (tem
, MEM
) <= rtx_cost (*g2
->location
, MEM
)
7209 /* Check each extension dependent giv in this class to see if its
7210 root biv is safe from wrapping in the interior mode, which would
7211 make the giv illegal. */
7214 check_ext_dependent_givs (bl
, loop_info
)
7215 struct iv_class
*bl
;
7216 struct loop_info
*loop_info
;
7218 int ze_ok
= 0, se_ok
= 0, info_ok
= 0;
7219 enum machine_mode biv_mode
= GET_MODE (bl
->biv
->src_reg
);
7220 HOST_WIDE_INT start_val
;
7221 unsigned HOST_WIDE_INT u_end_val
= 0;
7222 unsigned HOST_WIDE_INT u_start_val
= 0;
7224 struct induction
*v
;
7226 /* Make sure the iteration data is available. We must have
7227 constants in order to be certain of no overflow. */
7228 /* ??? An unknown iteration count with an increment of +-1
7229 combined with friendly exit tests of against an invariant
7230 value is also ameanable to optimization. Not implemented. */
7231 if (loop_info
->n_iterations
> 0
7232 && bl
->initial_value
7233 && GET_CODE (bl
->initial_value
) == CONST_INT
7234 && (incr
= biv_total_increment (bl
))
7235 && GET_CODE (incr
) == CONST_INT
7236 /* Make sure the host can represent the arithmetic. */
7237 && HOST_BITS_PER_WIDE_INT
>= GET_MODE_BITSIZE (biv_mode
))
7239 unsigned HOST_WIDE_INT abs_incr
, total_incr
;
7240 HOST_WIDE_INT s_end_val
;
7244 start_val
= INTVAL (bl
->initial_value
);
7245 u_start_val
= start_val
;
7247 neg_incr
= 0, abs_incr
= INTVAL (incr
);
7248 if (INTVAL (incr
) < 0)
7249 neg_incr
= 1, abs_incr
= -abs_incr
;
7250 total_incr
= abs_incr
* loop_info
->n_iterations
;
7252 /* Check for host arithmatic overflow. */
7253 if (total_incr
/ loop_info
->n_iterations
== abs_incr
)
7255 unsigned HOST_WIDE_INT u_max
;
7256 HOST_WIDE_INT s_max
;
7258 u_end_val
= start_val
+ (neg_incr
? -total_incr
: total_incr
);
7259 s_end_val
= u_end_val
;
7260 u_max
= GET_MODE_MASK (biv_mode
);
7263 /* Check zero extension of biv ok. */
7265 /* Check for host arithmatic overflow. */
7267 ? u_end_val
< u_start_val
7268 : u_end_val
> u_start_val
)
7269 /* Check for target arithmetic overflow. */
7271 ? 1 /* taken care of with host overflow */
7272 : u_end_val
<= u_max
))
7277 /* Check sign extension of biv ok. */
7278 /* ??? While it is true that overflow with signed and pointer
7279 arithmetic is undefined, I fear too many programmers don't
7280 keep this fact in mind -- myself included on occasion.
7281 So leave alone with the signed overflow optimizations. */
7282 if (start_val
>= -s_max
- 1
7283 /* Check for host arithmatic overflow. */
7285 ? s_end_val
< start_val
7286 : s_end_val
> start_val
)
7287 /* Check for target arithmetic overflow. */
7289 ? s_end_val
>= -s_max
- 1
7290 : s_end_val
<= s_max
))
7297 /* Invalidate givs that fail the tests. */
7298 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
7299 if (v
->ext_dependent
)
7301 enum rtx_code code
= GET_CODE (v
->ext_dependent
);
7314 /* We don't know whether this value is being used as either
7315 signed or unsigned, so to safely truncate we must satisfy
7316 both. The initial check here verifies the BIV itself;
7317 once that is successful we may check its range wrt the
7321 enum machine_mode outer_mode
= GET_MODE (v
->ext_dependent
);
7322 unsigned HOST_WIDE_INT max
= GET_MODE_MASK (outer_mode
) >> 1;
7324 /* We know from the above that both endpoints are nonnegative,
7325 and that there is no wrapping. Verify that both endpoints
7326 are within the (signed) range of the outer mode. */
7327 if (u_start_val
<= max
&& u_end_val
<= max
)
7338 if (loop_dump_stream
)
7340 fprintf (loop_dump_stream
,
7341 "Verified ext dependent giv at %d of reg %d\n",
7342 INSN_UID (v
->insn
), bl
->regno
);
7347 if (loop_dump_stream
)
7352 why
= "biv iteration values overflowed";
7356 incr
= biv_total_increment (bl
);
7357 if (incr
== const1_rtx
)
7358 why
= "biv iteration info incomplete; incr by 1";
7360 why
= "biv iteration info incomplete";
7363 fprintf (loop_dump_stream
,
7364 "Failed ext dependent giv at %d, %s\n",
7365 INSN_UID (v
->insn
), why
);
7368 bl
->all_reduced
= 0;
7373 /* Generate a version of VALUE in a mode appropriate for initializing V. */
7376 extend_value_for_giv (v
, value
)
7377 struct induction
*v
;
7380 rtx ext_dep
= v
->ext_dependent
;
7385 /* Recall that check_ext_dependent_givs verified that the known bounds
7386 of a biv did not overflow or wrap with respect to the extension for
7387 the giv. Therefore, constants need no additional adjustment. */
7388 if (CONSTANT_P (value
) && GET_MODE (value
) == VOIDmode
)
7391 /* Otherwise, we must adjust the value to compensate for the
7392 differing modes of the biv and the giv. */
7393 return gen_rtx_fmt_e (GET_CODE (ext_dep
), GET_MODE (ext_dep
), value
);
7396 struct combine_givs_stats
7403 cmp_combine_givs_stats (xp
, yp
)
7407 const struct combine_givs_stats
* const x
=
7408 (const struct combine_givs_stats
*) xp
;
7409 const struct combine_givs_stats
* const y
=
7410 (const struct combine_givs_stats
*) yp
;
7412 d
= y
->total_benefit
- x
->total_benefit
;
7413 /* Stabilize the sort. */
7415 d
= x
->giv_number
- y
->giv_number
;
7419 /* Check all pairs of givs for iv_class BL and see if any can be combined with
7420 any other. If so, point SAME to the giv combined with and set NEW_REG to
7421 be an expression (in terms of the other giv's DEST_REG) equivalent to the
7422 giv. Also, update BENEFIT and related fields for cost/benefit analysis. */
7425 combine_givs (regs
, bl
)
7426 struct loop_regs
*regs
;
7427 struct iv_class
*bl
;
7429 /* Additional benefit to add for being combined multiple times. */
7430 const int extra_benefit
= 3;
7432 struct induction
*g1
, *g2
, **giv_array
;
7433 int i
, j
, k
, giv_count
;
7434 struct combine_givs_stats
*stats
;
7437 /* Count givs, because bl->giv_count is incorrect here. */
7439 for (g1
= bl
->giv
; g1
; g1
= g1
->next_iv
)
7444 = (struct induction
**) alloca (giv_count
* sizeof (struct induction
*));
7446 for (g1
= bl
->giv
; g1
; g1
= g1
->next_iv
)
7448 giv_array
[i
++] = g1
;
7450 stats
= (struct combine_givs_stats
*) xcalloc (giv_count
, sizeof (*stats
));
7451 can_combine
= (rtx
*) xcalloc (giv_count
, giv_count
* sizeof (rtx
));
7453 for (i
= 0; i
< giv_count
; i
++)
7459 stats
[i
].giv_number
= i
;
7461 /* If a DEST_REG GIV is used only once, do not allow it to combine
7462 with anything, for in doing so we will gain nothing that cannot
7463 be had by simply letting the GIV with which we would have combined
7464 to be reduced on its own. The losage shows up in particular with
7465 DEST_ADDR targets on hosts with reg+reg addressing, though it can
7466 be seen elsewhere as well. */
7467 if (g1
->giv_type
== DEST_REG
7468 && (single_use
= regs
->array
[REGNO (g1
->dest_reg
)].single_usage
)
7469 && single_use
!= const0_rtx
)
7472 this_benefit
= g1
->benefit
;
7473 /* Add an additional weight for zero addends. */
7474 if (g1
->no_const_addval
)
7477 for (j
= 0; j
< giv_count
; j
++)
7483 && (this_combine
= combine_givs_p (g1
, g2
)) != NULL_RTX
)
7485 can_combine
[i
* giv_count
+ j
] = this_combine
;
7486 this_benefit
+= g2
->benefit
+ extra_benefit
;
7489 stats
[i
].total_benefit
= this_benefit
;
7492 /* Iterate, combining until we can't. */
7494 qsort (stats
, giv_count
, sizeof (*stats
), cmp_combine_givs_stats
);
7496 if (loop_dump_stream
)
7498 fprintf (loop_dump_stream
, "Sorted combine statistics:\n");
7499 for (k
= 0; k
< giv_count
; k
++)
7501 g1
= giv_array
[stats
[k
].giv_number
];
7502 if (!g1
->combined_with
&& !g1
->same
)
7503 fprintf (loop_dump_stream
, " {%d, %d}",
7504 INSN_UID (giv_array
[stats
[k
].giv_number
]->insn
),
7505 stats
[k
].total_benefit
);
7507 putc ('\n', loop_dump_stream
);
7510 for (k
= 0; k
< giv_count
; k
++)
7512 int g1_add_benefit
= 0;
7514 i
= stats
[k
].giv_number
;
7517 /* If it has already been combined, skip. */
7518 if (g1
->combined_with
|| g1
->same
)
7521 for (j
= 0; j
< giv_count
; j
++)
7524 if (g1
!= g2
&& can_combine
[i
* giv_count
+ j
]
7525 /* If it has already been combined, skip. */
7526 && ! g2
->same
&& ! g2
->combined_with
)
7530 g2
->new_reg
= can_combine
[i
* giv_count
+ j
];
7532 /* For destination, we now may replace by mem expression instead
7533 of register. This changes the costs considerably, so add the
7535 if (g2
->giv_type
== DEST_ADDR
)
7536 g2
->benefit
= (g2
->benefit
+ reg_address_cost
7537 - address_cost (g2
->new_reg
,
7538 GET_MODE (g2
->mem
)));
7539 g1
->combined_with
++;
7540 g1
->lifetime
+= g2
->lifetime
;
7542 g1_add_benefit
+= g2
->benefit
;
7544 /* ??? The new final_[bg]iv_value code does a much better job
7545 of finding replaceable giv's, and hence this code may no
7546 longer be necessary. */
7547 if (! g2
->replaceable
&& REG_USERVAR_P (g2
->dest_reg
))
7548 g1_add_benefit
-= copy_cost
;
7550 /* To help optimize the next set of combinations, remove
7551 this giv from the benefits of other potential mates. */
7552 for (l
= 0; l
< giv_count
; ++l
)
7554 int m
= stats
[l
].giv_number
;
7555 if (can_combine
[m
* giv_count
+ j
])
7556 stats
[l
].total_benefit
-= g2
->benefit
+ extra_benefit
;
7559 if (loop_dump_stream
)
7560 fprintf (loop_dump_stream
,
7561 "giv at %d combined with giv at %d; new benefit %d + %d, lifetime %d\n",
7562 INSN_UID (g2
->insn
), INSN_UID (g1
->insn
),
7563 g1
->benefit
, g1_add_benefit
, g1
->lifetime
);
7567 /* To help optimize the next set of combinations, remove
7568 this giv from the benefits of other potential mates. */
7569 if (g1
->combined_with
)
7571 for (j
= 0; j
< giv_count
; ++j
)
7573 int m
= stats
[j
].giv_number
;
7574 if (can_combine
[m
* giv_count
+ i
])
7575 stats
[j
].total_benefit
-= g1
->benefit
+ extra_benefit
;
7578 g1
->benefit
+= g1_add_benefit
;
7580 /* We've finished with this giv, and everything it touched.
7581 Restart the combination so that proper weights for the
7582 rest of the givs are properly taken into account. */
7583 /* ??? Ideally we would compact the arrays at this point, so
7584 as to not cover old ground. But sanely compacting
7585 can_combine is tricky. */
7595 /* Generate sequence for REG = B * M + A. */
7598 gen_add_mult (b
, m
, a
, reg
)
7599 rtx b
; /* initial value of basic induction variable */
7600 rtx m
; /* multiplicative constant */
7601 rtx a
; /* additive constant */
7602 rtx reg
; /* destination register */
7608 /* Use unsigned arithmetic. */
7609 result
= expand_mult_add (b
, reg
, m
, a
, GET_MODE (reg
), 1);
7611 emit_move_insn (reg
, result
);
7612 seq
= gen_sequence ();
7619 /* Update registers created in insn sequence SEQ. */
7622 loop_regs_update (loop
, seq
)
7623 const struct loop
*loop ATTRIBUTE_UNUSED
;
7626 /* Update register info for alias analysis. */
7628 if (GET_CODE (seq
) == SEQUENCE
)
7631 for (i
= 0; i
< XVECLEN (seq
, 0); ++i
)
7633 rtx set
= single_set (XVECEXP (seq
, 0, i
));
7634 if (set
&& GET_CODE (SET_DEST (set
)) == REG
)
7635 record_base_value (REGNO (SET_DEST (set
)), SET_SRC (set
), 0);
7640 if (GET_CODE (seq
) == SET
7641 && GET_CODE (SET_DEST (seq
)) == REG
)
7642 record_base_value (REGNO (SET_DEST (seq
)), SET_SRC (seq
), 0);
7647 /* EMIT code before BEFORE_BB/BEFORE_INSN to set REG = B * M + A. */
7650 loop_iv_add_mult_emit_before (loop
, b
, m
, a
, reg
, before_bb
, before_insn
)
7651 const struct loop
*loop
;
7652 rtx b
; /* initial value of basic induction variable */
7653 rtx m
; /* multiplicative constant */
7654 rtx a
; /* additive constant */
7655 rtx reg
; /* destination register */
7656 basic_block before_bb
;
7663 loop_iv_add_mult_hoist (loop
, b
, m
, a
, reg
);
7667 /* Use copy_rtx to prevent unexpected sharing of these rtx. */
7668 seq
= gen_add_mult (copy_rtx (b
), copy_rtx (m
), copy_rtx (a
), reg
);
7670 /* Increase the lifetime of any invariants moved further in code. */
7671 update_reg_last_use (a
, before_insn
);
7672 update_reg_last_use (b
, before_insn
);
7673 update_reg_last_use (m
, before_insn
);
7675 loop_insn_emit_before (loop
, before_bb
, before_insn
, seq
);
7677 /* It is possible that the expansion created lots of new registers.
7678 Iterate over the sequence we just created and record them all. */
7679 loop_regs_update (loop
, seq
);
7683 /* Emit insns in loop pre-header to set REG = B * M + A. */
7686 loop_iv_add_mult_sink (loop
, b
, m
, a
, reg
)
7687 const struct loop
*loop
;
7688 rtx b
; /* initial value of basic induction variable */
7689 rtx m
; /* multiplicative constant */
7690 rtx a
; /* additive constant */
7691 rtx reg
; /* destination register */
7695 /* Use copy_rtx to prevent unexpected sharing of these rtx. */
7696 seq
= gen_add_mult (copy_rtx (b
), copy_rtx (m
), copy_rtx (a
), reg
);
7698 /* Increase the lifetime of any invariants moved further in code.
7699 ???? Is this really necessary? */
7700 update_reg_last_use (a
, loop
->sink
);
7701 update_reg_last_use (b
, loop
->sink
);
7702 update_reg_last_use (m
, loop
->sink
);
7704 loop_insn_sink (loop
, seq
);
7706 /* It is possible that the expansion created lots of new registers.
7707 Iterate over the sequence we just created and record them all. */
7708 loop_regs_update (loop
, seq
);
7712 /* Emit insns after loop to set REG = B * M + A. */
7715 loop_iv_add_mult_hoist (loop
, b
, m
, a
, reg
)
7716 const struct loop
*loop
;
7717 rtx b
; /* initial value of basic induction variable */
7718 rtx m
; /* multiplicative constant */
7719 rtx a
; /* additive constant */
7720 rtx reg
; /* destination register */
7724 /* Use copy_rtx to prevent unexpected sharing of these rtx. */
7725 seq
= gen_add_mult (copy_rtx (b
), copy_rtx (m
), copy_rtx (a
), reg
);
7727 loop_insn_hoist (loop
, seq
);
7729 /* It is possible that the expansion created lots of new registers.
7730 Iterate over the sequence we just created and record them all. */
7731 loop_regs_update (loop
, seq
);
7736 /* Similar to gen_add_mult, but compute cost rather than generating
7740 iv_add_mult_cost (b
, m
, a
, reg
)
7741 rtx b
; /* initial value of basic induction variable */
7742 rtx m
; /* multiplicative constant */
7743 rtx a
; /* additive constant */
7744 rtx reg
; /* destination register */
7750 result
= expand_mult_add (b
, reg
, m
, a
, GET_MODE (reg
), 1);
7752 emit_move_insn (reg
, result
);
7753 last
= get_last_insn ();
7756 rtx t
= single_set (last
);
7758 cost
+= rtx_cost (SET_SRC (t
), SET
);
7759 last
= PREV_INSN (last
);
7765 /* Test whether A * B can be computed without
7766 an actual multiply insn. Value is 1 if so. */
7769 product_cheap_p (a
, b
)
7777 /* If only one is constant, make it B. */
7778 if (GET_CODE (a
) == CONST_INT
)
7779 tmp
= a
, a
= b
, b
= tmp
;
7781 /* If first constant, both constant, so don't need multiply. */
7782 if (GET_CODE (a
) == CONST_INT
)
7785 /* If second not constant, neither is constant, so would need multiply. */
7786 if (GET_CODE (b
) != CONST_INT
)
7789 /* One operand is constant, so might not need multiply insn. Generate the
7790 code for the multiply and see if a call or multiply, or long sequence
7791 of insns is generated. */
7794 expand_mult (GET_MODE (a
), a
, b
, NULL_RTX
, 1);
7795 tmp
= gen_sequence ();
7798 if (GET_CODE (tmp
) == SEQUENCE
)
7800 if (XVEC (tmp
, 0) == 0)
7802 else if (XVECLEN (tmp
, 0) > 3)
7805 for (i
= 0; i
< XVECLEN (tmp
, 0); i
++)
7807 rtx insn
= XVECEXP (tmp
, 0, i
);
7809 if (GET_CODE (insn
) != INSN
7810 || (GET_CODE (PATTERN (insn
)) == SET
7811 && GET_CODE (SET_SRC (PATTERN (insn
))) == MULT
)
7812 || (GET_CODE (PATTERN (insn
)) == PARALLEL
7813 && GET_CODE (XVECEXP (PATTERN (insn
), 0, 0)) == SET
7814 && GET_CODE (SET_SRC (XVECEXP (PATTERN (insn
), 0, 0))) == MULT
))
7821 else if (GET_CODE (tmp
) == SET
7822 && GET_CODE (SET_SRC (tmp
)) == MULT
)
7824 else if (GET_CODE (tmp
) == PARALLEL
7825 && GET_CODE (XVECEXP (tmp
, 0, 0)) == SET
7826 && GET_CODE (SET_SRC (XVECEXP (tmp
, 0, 0))) == MULT
)
7832 /* Check to see if loop can be terminated by a "decrement and branch until
7833 zero" instruction. If so, add a REG_NONNEG note to the branch insn if so.
7834 Also try reversing an increment loop to a decrement loop
7835 to see if the optimization can be performed.
7836 Value is nonzero if optimization was performed. */
7838 /* This is useful even if the architecture doesn't have such an insn,
7839 because it might change a loops which increments from 0 to n to a loop
7840 which decrements from n to 0. A loop that decrements to zero is usually
7841 faster than one that increments from zero. */
7843 /* ??? This could be rewritten to use some of the loop unrolling procedures,
7844 such as approx_final_value, biv_total_increment, loop_iterations, and
7845 final_[bg]iv_value. */
7848 check_dbra_loop (loop
, insn_count
)
7852 struct loop_info
*loop_info
= LOOP_INFO (loop
);
7853 struct loop_regs
*regs
= LOOP_REGS (loop
);
7854 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
7855 struct iv_class
*bl
;
7862 rtx before_comparison
;
7866 int compare_and_branch
;
7867 rtx loop_start
= loop
->start
;
7868 rtx loop_end
= loop
->end
;
7870 /* If last insn is a conditional branch, and the insn before tests a
7871 register value, try to optimize it. Otherwise, we can't do anything. */
7873 jump
= PREV_INSN (loop_end
);
7874 comparison
= get_condition_for_loop (loop
, jump
);
7875 if (comparison
== 0)
7877 if (!onlyjump_p (jump
))
7880 /* Try to compute whether the compare/branch at the loop end is one or
7881 two instructions. */
7882 get_condition (jump
, &first_compare
);
7883 if (first_compare
== jump
)
7884 compare_and_branch
= 1;
7885 else if (first_compare
== prev_nonnote_insn (jump
))
7886 compare_and_branch
= 2;
7891 /* If more than one condition is present to control the loop, then
7892 do not proceed, as this function does not know how to rewrite
7893 loop tests with more than one condition.
7895 Look backwards from the first insn in the last comparison
7896 sequence and see if we've got another comparison sequence. */
7899 if ((jump1
= prev_nonnote_insn (first_compare
)) != loop
->cont
)
7900 if (GET_CODE (jump1
) == JUMP_INSN
)
7904 /* Check all of the bivs to see if the compare uses one of them.
7905 Skip biv's set more than once because we can't guarantee that
7906 it will be zero on the last iteration. Also skip if the biv is
7907 used between its update and the test insn. */
7909 for (bl
= ivs
->list
; bl
; bl
= bl
->next
)
7911 if (bl
->biv_count
== 1
7912 && ! bl
->biv
->maybe_multiple
7913 && bl
->biv
->dest_reg
== XEXP (comparison
, 0)
7914 && ! reg_used_between_p (regno_reg_rtx
[bl
->regno
], bl
->biv
->insn
,
7922 /* Look for the case where the basic induction variable is always
7923 nonnegative, and equals zero on the last iteration.
7924 In this case, add a reg_note REG_NONNEG, which allows the
7925 m68k DBRA instruction to be used. */
7927 if (((GET_CODE (comparison
) == GT
7928 && GET_CODE (XEXP (comparison
, 1)) == CONST_INT
7929 && INTVAL (XEXP (comparison
, 1)) == -1)
7930 || (GET_CODE (comparison
) == NE
&& XEXP (comparison
, 1) == const0_rtx
))
7931 && GET_CODE (bl
->biv
->add_val
) == CONST_INT
7932 && INTVAL (bl
->biv
->add_val
) < 0)
7934 /* Initial value must be greater than 0,
7935 init_val % -dec_value == 0 to ensure that it equals zero on
7936 the last iteration */
7938 if (GET_CODE (bl
->initial_value
) == CONST_INT
7939 && INTVAL (bl
->initial_value
) > 0
7940 && (INTVAL (bl
->initial_value
)
7941 % (-INTVAL (bl
->biv
->add_val
))) == 0)
7943 /* register always nonnegative, add REG_NOTE to branch */
7944 if (! find_reg_note (jump
, REG_NONNEG
, NULL_RTX
))
7946 = gen_rtx_EXPR_LIST (REG_NONNEG
, bl
->biv
->dest_reg
,
7953 /* If the decrement is 1 and the value was tested as >= 0 before
7954 the loop, then we can safely optimize. */
7955 for (p
= loop_start
; p
; p
= PREV_INSN (p
))
7957 if (GET_CODE (p
) == CODE_LABEL
)
7959 if (GET_CODE (p
) != JUMP_INSN
)
7962 before_comparison
= get_condition_for_loop (loop
, p
);
7963 if (before_comparison
7964 && XEXP (before_comparison
, 0) == bl
->biv
->dest_reg
7965 && GET_CODE (before_comparison
) == LT
7966 && XEXP (before_comparison
, 1) == const0_rtx
7967 && ! reg_set_between_p (bl
->biv
->dest_reg
, p
, loop_start
)
7968 && INTVAL (bl
->biv
->add_val
) == -1)
7970 if (! find_reg_note (jump
, REG_NONNEG
, NULL_RTX
))
7972 = gen_rtx_EXPR_LIST (REG_NONNEG
, bl
->biv
->dest_reg
,
7980 else if (GET_CODE (bl
->biv
->add_val
) == CONST_INT
7981 && INTVAL (bl
->biv
->add_val
) > 0)
7983 /* Try to change inc to dec, so can apply above optimization. */
7985 all registers modified are induction variables or invariant,
7986 all memory references have non-overlapping addresses
7987 (obviously true if only one write)
7988 allow 2 insns for the compare/jump at the end of the loop. */
7989 /* Also, we must avoid any instructions which use both the reversed
7990 biv and another biv. Such instructions will fail if the loop is
7991 reversed. We meet this condition by requiring that either
7992 no_use_except_counting is true, or else that there is only
7994 int num_nonfixed_reads
= 0;
7995 /* 1 if the iteration var is used only to count iterations. */
7996 int no_use_except_counting
= 0;
7997 /* 1 if the loop has no memory store, or it has a single memory store
7998 which is reversible. */
7999 int reversible_mem_store
= 1;
8001 if (bl
->giv_count
== 0
8002 && !loop
->exit_count
8003 && !loop_info
->has_multiple_exit_targets
)
8005 rtx bivreg
= regno_reg_rtx
[bl
->regno
];
8006 struct iv_class
*blt
;
8008 /* If there are no givs for this biv, and the only exit is the
8009 fall through at the end of the loop, then
8010 see if perhaps there are no uses except to count. */
8011 no_use_except_counting
= 1;
8012 for (p
= loop_start
; p
!= loop_end
; p
= NEXT_INSN (p
))
8015 rtx set
= single_set (p
);
8017 if (set
&& GET_CODE (SET_DEST (set
)) == REG
8018 && REGNO (SET_DEST (set
)) == bl
->regno
)
8019 /* An insn that sets the biv is okay. */
8021 else if ((p
== prev_nonnote_insn (prev_nonnote_insn (loop_end
))
8022 || p
== prev_nonnote_insn (loop_end
))
8023 && reg_mentioned_p (bivreg
, PATTERN (p
)))
8025 /* If either of these insns uses the biv and sets a pseudo
8026 that has more than one usage, then the biv has uses
8027 other than counting since it's used to derive a value
8028 that is used more than one time. */
8029 note_stores (PATTERN (p
), note_set_pseudo_multiple_uses
,
8031 if (regs
->multiple_uses
)
8033 no_use_except_counting
= 0;
8037 else if (reg_mentioned_p (bivreg
, PATTERN (p
)))
8039 no_use_except_counting
= 0;
8044 /* A biv has uses besides counting if it is used to set
8046 for (blt
= ivs
->list
; blt
; blt
= blt
->next
)
8048 && reg_mentioned_p (bivreg
, SET_SRC (blt
->init_set
)))
8050 no_use_except_counting
= 0;
8055 if (no_use_except_counting
)
8056 /* No need to worry about MEMs. */
8058 else if (loop_info
->num_mem_sets
<= 1)
8060 for (p
= loop_start
; p
!= loop_end
; p
= NEXT_INSN (p
))
8062 num_nonfixed_reads
+= count_nonfixed_reads (loop
, PATTERN (p
));
8064 /* If the loop has a single store, and the destination address is
8065 invariant, then we can't reverse the loop, because this address
8066 might then have the wrong value at loop exit.
8067 This would work if the source was invariant also, however, in that
8068 case, the insn should have been moved out of the loop. */
8070 if (loop_info
->num_mem_sets
== 1)
8072 struct induction
*v
;
8074 /* If we could prove that each of the memory locations
8075 written to was different, then we could reverse the
8076 store -- but we don't presently have any way of
8078 reversible_mem_store
= 0;
8080 /* If the store depends on a register that is set after the
8081 store, it depends on the initial value, and is thus not
8083 for (v
= bl
->giv
; reversible_mem_store
&& v
; v
= v
->next_iv
)
8085 if (v
->giv_type
== DEST_REG
8086 && reg_mentioned_p (v
->dest_reg
,
8087 PATTERN (loop_info
->first_loop_store_insn
))
8088 && loop_insn_first_p (loop_info
->first_loop_store_insn
,
8090 reversible_mem_store
= 0;
8097 /* This code only acts for innermost loops. Also it simplifies
8098 the memory address check by only reversing loops with
8099 zero or one memory access.
8100 Two memory accesses could involve parts of the same array,
8101 and that can't be reversed.
8102 If the biv is used only for counting, than we don't need to worry
8103 about all these things. */
8105 if ((num_nonfixed_reads
<= 1
8106 && ! loop_info
->has_nonconst_call
8107 && ! loop_info
->has_volatile
8108 && reversible_mem_store
8109 && (bl
->giv_count
+ bl
->biv_count
+ loop_info
->num_mem_sets
8110 + num_unmoved_movables (loop
) + compare_and_branch
== insn_count
)
8111 && (bl
== ivs
->list
&& bl
->next
== 0))
8112 || no_use_except_counting
)
8116 /* Loop can be reversed. */
8117 if (loop_dump_stream
)
8118 fprintf (loop_dump_stream
, "Can reverse loop\n");
8120 /* Now check other conditions:
8122 The increment must be a constant, as must the initial value,
8123 and the comparison code must be LT.
8125 This test can probably be improved since +/- 1 in the constant
8126 can be obtained by changing LT to LE and vice versa; this is
8130 /* for constants, LE gets turned into LT */
8131 && (GET_CODE (comparison
) == LT
8132 || (GET_CODE (comparison
) == LE
8133 && no_use_except_counting
)))
8135 HOST_WIDE_INT add_val
, add_adjust
, comparison_val
= 0;
8136 rtx initial_value
, comparison_value
;
8138 enum rtx_code cmp_code
;
8139 int comparison_const_width
;
8140 unsigned HOST_WIDE_INT comparison_sign_mask
;
8142 add_val
= INTVAL (bl
->biv
->add_val
);
8143 comparison_value
= XEXP (comparison
, 1);
8144 if (GET_MODE (comparison_value
) == VOIDmode
)
8145 comparison_const_width
8146 = GET_MODE_BITSIZE (GET_MODE (XEXP (comparison
, 0)));
8148 comparison_const_width
8149 = GET_MODE_BITSIZE (GET_MODE (comparison_value
));
8150 if (comparison_const_width
> HOST_BITS_PER_WIDE_INT
)
8151 comparison_const_width
= HOST_BITS_PER_WIDE_INT
;
8152 comparison_sign_mask
8153 = (unsigned HOST_WIDE_INT
) 1 << (comparison_const_width
- 1);
8155 /* If the comparison value is not a loop invariant, then we
8156 can not reverse this loop.
8158 ??? If the insns which initialize the comparison value as
8159 a whole compute an invariant result, then we could move
8160 them out of the loop and proceed with loop reversal. */
8161 if (! loop_invariant_p (loop
, comparison_value
))
8164 if (GET_CODE (comparison_value
) == CONST_INT
)
8165 comparison_val
= INTVAL (comparison_value
);
8166 initial_value
= bl
->initial_value
;
8168 /* Normalize the initial value if it is an integer and
8169 has no other use except as a counter. This will allow
8170 a few more loops to be reversed. */
8171 if (no_use_except_counting
8172 && GET_CODE (comparison_value
) == CONST_INT
8173 && GET_CODE (initial_value
) == CONST_INT
)
8175 comparison_val
= comparison_val
- INTVAL (bl
->initial_value
);
8176 /* The code below requires comparison_val to be a multiple
8177 of add_val in order to do the loop reversal, so
8178 round up comparison_val to a multiple of add_val.
8179 Since comparison_value is constant, we know that the
8180 current comparison code is LT. */
8181 comparison_val
= comparison_val
+ add_val
- 1;
8183 -= (unsigned HOST_WIDE_INT
) comparison_val
% add_val
;
8184 /* We postpone overflow checks for COMPARISON_VAL here;
8185 even if there is an overflow, we might still be able to
8186 reverse the loop, if converting the loop exit test to
8188 initial_value
= const0_rtx
;
8191 /* First check if we can do a vanilla loop reversal. */
8192 if (initial_value
== const0_rtx
8193 /* If we have a decrement_and_branch_on_count,
8194 prefer the NE test, since this will allow that
8195 instruction to be generated. Note that we must
8196 use a vanilla loop reversal if the biv is used to
8197 calculate a giv or has a non-counting use. */
8198 #if ! defined (HAVE_decrement_and_branch_until_zero) \
8199 && defined (HAVE_decrement_and_branch_on_count)
8200 && (! (add_val
== 1 && loop
->vtop
8201 && (bl
->biv_count
== 0
8202 || no_use_except_counting
)))
8204 && GET_CODE (comparison_value
) == CONST_INT
8205 /* Now do postponed overflow checks on COMPARISON_VAL. */
8206 && ! (((comparison_val
- add_val
) ^ INTVAL (comparison_value
))
8207 & comparison_sign_mask
))
8209 /* Register will always be nonnegative, with value
8210 0 on last iteration */
8211 add_adjust
= add_val
;
8215 else if (add_val
== 1 && loop
->vtop
8216 && (bl
->biv_count
== 0
8217 || no_use_except_counting
))
8225 if (GET_CODE (comparison
) == LE
)
8226 add_adjust
-= add_val
;
8228 /* If the initial value is not zero, or if the comparison
8229 value is not an exact multiple of the increment, then we
8230 can not reverse this loop. */
8231 if (initial_value
== const0_rtx
8232 && GET_CODE (comparison_value
) == CONST_INT
)
8234 if (((unsigned HOST_WIDE_INT
) comparison_val
% add_val
) != 0)
8239 if (! no_use_except_counting
|| add_val
!= 1)
8243 final_value
= comparison_value
;
8245 /* Reset these in case we normalized the initial value
8246 and comparison value above. */
8247 if (GET_CODE (comparison_value
) == CONST_INT
8248 && GET_CODE (initial_value
) == CONST_INT
)
8250 comparison_value
= GEN_INT (comparison_val
);
8252 = GEN_INT (comparison_val
+ INTVAL (bl
->initial_value
));
8254 bl
->initial_value
= initial_value
;
8256 /* Save some info needed to produce the new insns. */
8257 reg
= bl
->biv
->dest_reg
;
8258 jump_label
= condjump_label (PREV_INSN (loop_end
));
8259 new_add_val
= GEN_INT (-INTVAL (bl
->biv
->add_val
));
8261 /* Set start_value; if this is not a CONST_INT, we need
8263 Initialize biv to start_value before loop start.
8264 The old initializing insn will be deleted as a
8265 dead store by flow.c. */
8266 if (initial_value
== const0_rtx
8267 && GET_CODE (comparison_value
) == CONST_INT
)
8269 start_value
= GEN_INT (comparison_val
- add_adjust
);
8270 loop_insn_hoist (loop
, gen_move_insn (reg
, start_value
));
8272 else if (GET_CODE (initial_value
) == CONST_INT
)
8274 enum machine_mode mode
= GET_MODE (reg
);
8275 rtx offset
= GEN_INT (-INTVAL (initial_value
) - add_adjust
);
8276 rtx add_insn
= gen_add3_insn (reg
, comparison_value
, offset
);
8282 = gen_rtx_PLUS (mode
, comparison_value
, offset
);
8283 loop_insn_hoist (loop
, add_insn
);
8284 if (GET_CODE (comparison
) == LE
)
8285 final_value
= gen_rtx_PLUS (mode
, comparison_value
,
8288 else if (! add_adjust
)
8290 enum machine_mode mode
= GET_MODE (reg
);
8291 rtx sub_insn
= gen_sub3_insn (reg
, comparison_value
,
8297 = gen_rtx_MINUS (mode
, comparison_value
, initial_value
);
8298 loop_insn_hoist (loop
, sub_insn
);
8301 /* We could handle the other cases too, but it'll be
8302 better to have a testcase first. */
8305 /* We may not have a single insn which can increment a reg, so
8306 create a sequence to hold all the insns from expand_inc. */
8308 expand_inc (reg
, new_add_val
);
8309 tem
= gen_sequence ();
8312 p
= loop_insn_emit_before (loop
, 0, bl
->biv
->insn
, tem
);
8313 delete_insn (bl
->biv
->insn
);
8315 /* Update biv info to reflect its new status. */
8317 bl
->initial_value
= start_value
;
8318 bl
->biv
->add_val
= new_add_val
;
8320 /* Update loop info. */
8321 loop_info
->initial_value
= reg
;
8322 loop_info
->initial_equiv_value
= reg
;
8323 loop_info
->final_value
= const0_rtx
;
8324 loop_info
->final_equiv_value
= const0_rtx
;
8325 loop_info
->comparison_value
= const0_rtx
;
8326 loop_info
->comparison_code
= cmp_code
;
8327 loop_info
->increment
= new_add_val
;
8329 /* Inc LABEL_NUSES so that delete_insn will
8330 not delete the label. */
8331 LABEL_NUSES (XEXP (jump_label
, 0))++;
8333 /* Emit an insn after the end of the loop to set the biv's
8334 proper exit value if it is used anywhere outside the loop. */
8335 if ((REGNO_LAST_UID (bl
->regno
) != INSN_UID (first_compare
))
8337 || REGNO_FIRST_UID (bl
->regno
) != INSN_UID (bl
->init_insn
))
8338 loop_insn_sink (loop
, gen_move_insn (reg
, final_value
));
8340 /* Delete compare/branch at end of loop. */
8341 delete_related_insns (PREV_INSN (loop_end
));
8342 if (compare_and_branch
== 2)
8343 delete_related_insns (first_compare
);
8345 /* Add new compare/branch insn at end of loop. */
8347 emit_cmp_and_jump_insns (reg
, const0_rtx
, cmp_code
, NULL_RTX
,
8349 XEXP (jump_label
, 0));
8350 tem
= gen_sequence ();
8352 emit_jump_insn_before (tem
, loop_end
);
8354 for (tem
= PREV_INSN (loop_end
);
8355 tem
&& GET_CODE (tem
) != JUMP_INSN
;
8356 tem
= PREV_INSN (tem
))
8360 JUMP_LABEL (tem
) = XEXP (jump_label
, 0);
8366 /* Increment of LABEL_NUSES done above. */
8367 /* Register is now always nonnegative,
8368 so add REG_NONNEG note to the branch. */
8369 REG_NOTES (tem
) = gen_rtx_EXPR_LIST (REG_NONNEG
, reg
,
8375 /* No insn may reference both the reversed and another biv or it
8376 will fail (see comment near the top of the loop reversal
8378 Earlier on, we have verified that the biv has no use except
8379 counting, or it is the only biv in this function.
8380 However, the code that computes no_use_except_counting does
8381 not verify reg notes. It's possible to have an insn that
8382 references another biv, and has a REG_EQUAL note with an
8383 expression based on the reversed biv. To avoid this case,
8384 remove all REG_EQUAL notes based on the reversed biv
8386 for (p
= loop_start
; p
!= loop_end
; p
= NEXT_INSN (p
))
8390 rtx set
= single_set (p
);
8391 /* If this is a set of a GIV based on the reversed biv, any
8392 REG_EQUAL notes should still be correct. */
8394 || GET_CODE (SET_DEST (set
)) != REG
8395 || (size_t) REGNO (SET_DEST (set
)) >= ivs
->n_regs
8396 || REG_IV_TYPE (ivs
, REGNO (SET_DEST (set
))) != GENERAL_INDUCT
8397 || REG_IV_INFO (ivs
, REGNO (SET_DEST (set
)))->src_reg
!= bl
->biv
->src_reg
)
8398 for (pnote
= ®_NOTES (p
); *pnote
;)
8400 if (REG_NOTE_KIND (*pnote
) == REG_EQUAL
8401 && reg_mentioned_p (regno_reg_rtx
[bl
->regno
],
8403 *pnote
= XEXP (*pnote
, 1);
8405 pnote
= &XEXP (*pnote
, 1);
8409 /* Mark that this biv has been reversed. Each giv which depends
8410 on this biv, and which is also live past the end of the loop
8411 will have to be fixed up. */
8415 if (loop_dump_stream
)
8417 fprintf (loop_dump_stream
, "Reversed loop");
8419 fprintf (loop_dump_stream
, " and added reg_nonneg\n");
8421 fprintf (loop_dump_stream
, "\n");
8432 /* Verify whether the biv BL appears to be eliminable,
8433 based on the insns in the loop that refer to it.
8435 If ELIMINATE_P is non-zero, actually do the elimination.
8437 THRESHOLD and INSN_COUNT are from loop_optimize and are used to
8438 determine whether invariant insns should be placed inside or at the
8439 start of the loop. */
8442 maybe_eliminate_biv (loop
, bl
, eliminate_p
, threshold
, insn_count
)
8443 const struct loop
*loop
;
8444 struct iv_class
*bl
;
8446 int threshold
, insn_count
;
8448 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
8449 rtx reg
= bl
->biv
->dest_reg
;
8452 /* Scan all insns in the loop, stopping if we find one that uses the
8453 biv in a way that we cannot eliminate. */
8455 for (p
= loop
->start
; p
!= loop
->end
; p
= NEXT_INSN (p
))
8457 enum rtx_code code
= GET_CODE (p
);
8458 basic_block where_bb
= 0;
8459 rtx where_insn
= threshold
>= insn_count
? 0 : p
;
8461 /* If this is a libcall that sets a giv, skip ahead to its end. */
8462 if (GET_RTX_CLASS (code
) == 'i')
8464 rtx note
= find_reg_note (p
, REG_LIBCALL
, NULL_RTX
);
8468 rtx last
= XEXP (note
, 0);
8469 rtx set
= single_set (last
);
8471 if (set
&& GET_CODE (SET_DEST (set
)) == REG
)
8473 unsigned int regno
= REGNO (SET_DEST (set
));
8475 if (regno
< ivs
->n_regs
8476 && REG_IV_TYPE (ivs
, regno
) == GENERAL_INDUCT
8477 && REG_IV_INFO (ivs
, regno
)->src_reg
== bl
->biv
->src_reg
)
8482 if ((code
== INSN
|| code
== JUMP_INSN
|| code
== CALL_INSN
)
8483 && reg_mentioned_p (reg
, PATTERN (p
))
8484 && ! maybe_eliminate_biv_1 (loop
, PATTERN (p
), p
, bl
,
8485 eliminate_p
, where_bb
, where_insn
))
8487 if (loop_dump_stream
)
8488 fprintf (loop_dump_stream
,
8489 "Cannot eliminate biv %d: biv used in insn %d.\n",
8490 bl
->regno
, INSN_UID (p
));
8497 if (loop_dump_stream
)
8498 fprintf (loop_dump_stream
, "biv %d %s eliminated.\n",
8499 bl
->regno
, eliminate_p
? "was" : "can be");
8506 /* INSN and REFERENCE are instructions in the same insn chain.
8507 Return non-zero if INSN is first. */
8510 loop_insn_first_p (insn
, reference
)
8511 rtx insn
, reference
;
8515 for (p
= insn
, q
= reference
;;)
8517 /* Start with test for not first so that INSN == REFERENCE yields not
8519 if (q
== insn
|| ! p
)
8521 if (p
== reference
|| ! q
)
8524 /* Either of P or Q might be a NOTE. Notes have the same LUID as the
8525 previous insn, hence the <= comparison below does not work if
8527 if (INSN_UID (p
) < max_uid_for_loop
8528 && INSN_UID (q
) < max_uid_for_loop
8529 && GET_CODE (p
) != NOTE
)
8530 return INSN_LUID (p
) <= INSN_LUID (q
);
8532 if (INSN_UID (p
) >= max_uid_for_loop
8533 || GET_CODE (p
) == NOTE
)
8535 if (INSN_UID (q
) >= max_uid_for_loop
)
8540 /* We are trying to eliminate BIV in INSN using GIV. Return non-zero if
8541 the offset that we have to take into account due to auto-increment /
8542 div derivation is zero. */
8544 biv_elimination_giv_has_0_offset (biv
, giv
, insn
)
8545 struct induction
*biv
, *giv
;
8548 /* If the giv V had the auto-inc address optimization applied
8549 to it, and INSN occurs between the giv insn and the biv
8550 insn, then we'd have to adjust the value used here.
8551 This is rare, so we don't bother to make this possible. */
8552 if (giv
->auto_inc_opt
8553 && ((loop_insn_first_p (giv
->insn
, insn
)
8554 && loop_insn_first_p (insn
, biv
->insn
))
8555 || (loop_insn_first_p (biv
->insn
, insn
)
8556 && loop_insn_first_p (insn
, giv
->insn
))))
8562 /* If BL appears in X (part of the pattern of INSN), see if we can
8563 eliminate its use. If so, return 1. If not, return 0.
8565 If BIV does not appear in X, return 1.
8567 If ELIMINATE_P is non-zero, actually do the elimination.
8568 WHERE_INSN/WHERE_BB indicate where extra insns should be added.
8569 Depending on how many items have been moved out of the loop, it
8570 will either be before INSN (when WHERE_INSN is non-zero) or at the
8571 start of the loop (when WHERE_INSN is zero). */
8574 maybe_eliminate_biv_1 (loop
, x
, insn
, bl
, eliminate_p
, where_bb
, where_insn
)
8575 const struct loop
*loop
;
8577 struct iv_class
*bl
;
8579 basic_block where_bb
;
8582 enum rtx_code code
= GET_CODE (x
);
8583 rtx reg
= bl
->biv
->dest_reg
;
8584 enum machine_mode mode
= GET_MODE (reg
);
8585 struct induction
*v
;
8597 /* If we haven't already been able to do something with this BIV,
8598 we can't eliminate it. */
8604 /* If this sets the BIV, it is not a problem. */
8605 if (SET_DEST (x
) == reg
)
8608 /* If this is an insn that defines a giv, it is also ok because
8609 it will go away when the giv is reduced. */
8610 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
8611 if (v
->giv_type
== DEST_REG
&& SET_DEST (x
) == v
->dest_reg
)
8615 if (SET_DEST (x
) == cc0_rtx
&& SET_SRC (x
) == reg
)
8617 /* Can replace with any giv that was reduced and
8618 that has (MULT_VAL != 0) and (ADD_VAL == 0).
8619 Require a constant for MULT_VAL, so we know it's nonzero.
8620 ??? We disable this optimization to avoid potential
8623 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
8624 if (GET_CODE (v
->mult_val
) == CONST_INT
&& v
->mult_val
!= const0_rtx
8625 && v
->add_val
== const0_rtx
8626 && ! v
->ignore
&& ! v
->maybe_dead
&& v
->always_computable
8630 if (! biv_elimination_giv_has_0_offset (bl
->biv
, v
, insn
))
8636 /* If the giv has the opposite direction of change,
8637 then reverse the comparison. */
8638 if (INTVAL (v
->mult_val
) < 0)
8639 new = gen_rtx_COMPARE (GET_MODE (v
->new_reg
),
8640 const0_rtx
, v
->new_reg
);
8644 /* We can probably test that giv's reduced reg. */
8645 if (validate_change (insn
, &SET_SRC (x
), new, 0))
8649 /* Look for a giv with (MULT_VAL != 0) and (ADD_VAL != 0);
8650 replace test insn with a compare insn (cmp REDUCED_GIV ADD_VAL).
8651 Require a constant for MULT_VAL, so we know it's nonzero.
8652 ??? Do this only if ADD_VAL is a pointer to avoid a potential
8653 overflow problem. */
8655 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
8656 if (GET_CODE (v
->mult_val
) == CONST_INT
8657 && v
->mult_val
!= const0_rtx
8658 && ! v
->ignore
&& ! v
->maybe_dead
&& v
->always_computable
8660 && (GET_CODE (v
->add_val
) == SYMBOL_REF
8661 || GET_CODE (v
->add_val
) == LABEL_REF
8662 || GET_CODE (v
->add_val
) == CONST
8663 || (GET_CODE (v
->add_val
) == REG
8664 && REG_POINTER (v
->add_val
))))
8666 if (! biv_elimination_giv_has_0_offset (bl
->biv
, v
, insn
))
8672 /* If the giv has the opposite direction of change,
8673 then reverse the comparison. */
8674 if (INTVAL (v
->mult_val
) < 0)
8675 new = gen_rtx_COMPARE (VOIDmode
, copy_rtx (v
->add_val
),
8678 new = gen_rtx_COMPARE (VOIDmode
, v
->new_reg
,
8679 copy_rtx (v
->add_val
));
8681 /* Replace biv with the giv's reduced register. */
8682 update_reg_last_use (v
->add_val
, insn
);
8683 if (validate_change (insn
, &SET_SRC (PATTERN (insn
)), new, 0))
8686 /* Insn doesn't support that constant or invariant. Copy it
8687 into a register (it will be a loop invariant.) */
8688 tem
= gen_reg_rtx (GET_MODE (v
->new_reg
));
8690 loop_insn_emit_before (loop
, 0, where_insn
,
8692 copy_rtx (v
->add_val
)));
8694 /* Substitute the new register for its invariant value in
8695 the compare expression. */
8696 XEXP (new, (INTVAL (v
->mult_val
) < 0) ? 0 : 1) = tem
;
8697 if (validate_change (insn
, &SET_SRC (PATTERN (insn
)), new, 0))
8706 case GT
: case GE
: case GTU
: case GEU
:
8707 case LT
: case LE
: case LTU
: case LEU
:
8708 /* See if either argument is the biv. */
8709 if (XEXP (x
, 0) == reg
)
8710 arg
= XEXP (x
, 1), arg_operand
= 1;
8711 else if (XEXP (x
, 1) == reg
)
8712 arg
= XEXP (x
, 0), arg_operand
= 0;
8716 if (CONSTANT_P (arg
))
8718 /* First try to replace with any giv that has constant positive
8719 mult_val and constant add_val. We might be able to support
8720 negative mult_val, but it seems complex to do it in general. */
8722 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
8723 if (GET_CODE (v
->mult_val
) == CONST_INT
8724 && INTVAL (v
->mult_val
) > 0
8725 && (GET_CODE (v
->add_val
) == SYMBOL_REF
8726 || GET_CODE (v
->add_val
) == LABEL_REF
8727 || GET_CODE (v
->add_val
) == CONST
8728 || (GET_CODE (v
->add_val
) == REG
8729 && REG_POINTER (v
->add_val
)))
8730 && ! v
->ignore
&& ! v
->maybe_dead
&& v
->always_computable
8733 if (! biv_elimination_giv_has_0_offset (bl
->biv
, v
, insn
))
8739 /* Replace biv with the giv's reduced reg. */
8740 validate_change (insn
, &XEXP (x
, 1 - arg_operand
), v
->new_reg
, 1);
8742 /* If all constants are actually constant integers and
8743 the derived constant can be directly placed in the COMPARE,
8745 if (GET_CODE (arg
) == CONST_INT
8746 && GET_CODE (v
->mult_val
) == CONST_INT
8747 && GET_CODE (v
->add_val
) == CONST_INT
)
8749 validate_change (insn
, &XEXP (x
, arg_operand
),
8750 GEN_INT (INTVAL (arg
)
8751 * INTVAL (v
->mult_val
)
8752 + INTVAL (v
->add_val
)), 1);
8756 /* Otherwise, load it into a register. */
8757 tem
= gen_reg_rtx (mode
);
8758 loop_iv_add_mult_emit_before (loop
, arg
,
8759 v
->mult_val
, v
->add_val
,
8760 tem
, where_bb
, where_insn
);
8761 validate_change (insn
, &XEXP (x
, arg_operand
), tem
, 1);
8763 if (apply_change_group ())
8767 /* Look for giv with positive constant mult_val and nonconst add_val.
8768 Insert insns to calculate new compare value.
8769 ??? Turn this off due to possible overflow. */
8771 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
8772 if (GET_CODE (v
->mult_val
) == CONST_INT
8773 && INTVAL (v
->mult_val
) > 0
8774 && ! v
->ignore
&& ! v
->maybe_dead
&& v
->always_computable
8780 if (! biv_elimination_giv_has_0_offset (bl
->biv
, v
, insn
))
8786 tem
= gen_reg_rtx (mode
);
8788 /* Replace biv with giv's reduced register. */
8789 validate_change (insn
, &XEXP (x
, 1 - arg_operand
),
8792 /* Compute value to compare against. */
8793 loop_iv_add_mult_emit_before (loop
, arg
,
8794 v
->mult_val
, v
->add_val
,
8795 tem
, where_bb
, where_insn
);
8796 /* Use it in this insn. */
8797 validate_change (insn
, &XEXP (x
, arg_operand
), tem
, 1);
8798 if (apply_change_group ())
8802 else if (GET_CODE (arg
) == REG
|| GET_CODE (arg
) == MEM
)
8804 if (loop_invariant_p (loop
, arg
) == 1)
8806 /* Look for giv with constant positive mult_val and nonconst
8807 add_val. Insert insns to compute new compare value.
8808 ??? Turn this off due to possible overflow. */
8810 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
8811 if (GET_CODE (v
->mult_val
) == CONST_INT
&& INTVAL (v
->mult_val
) > 0
8812 && ! v
->ignore
&& ! v
->maybe_dead
&& v
->always_computable
8818 if (! biv_elimination_giv_has_0_offset (bl
->biv
, v
, insn
))
8824 tem
= gen_reg_rtx (mode
);
8826 /* Replace biv with giv's reduced register. */
8827 validate_change (insn
, &XEXP (x
, 1 - arg_operand
),
8830 /* Compute value to compare against. */
8831 loop_iv_add_mult_emit_before (loop
, arg
,
8832 v
->mult_val
, v
->add_val
,
8833 tem
, where_bb
, where_insn
);
8834 validate_change (insn
, &XEXP (x
, arg_operand
), tem
, 1);
8835 if (apply_change_group ())
8840 /* This code has problems. Basically, you can't know when
8841 seeing if we will eliminate BL, whether a particular giv
8842 of ARG will be reduced. If it isn't going to be reduced,
8843 we can't eliminate BL. We can try forcing it to be reduced,
8844 but that can generate poor code.
8846 The problem is that the benefit of reducing TV, below should
8847 be increased if BL can actually be eliminated, but this means
8848 we might have to do a topological sort of the order in which
8849 we try to process biv. It doesn't seem worthwhile to do
8850 this sort of thing now. */
8853 /* Otherwise the reg compared with had better be a biv. */
8854 if (GET_CODE (arg
) != REG
8855 || REG_IV_TYPE (ivs
, REGNO (arg
)) != BASIC_INDUCT
)
8858 /* Look for a pair of givs, one for each biv,
8859 with identical coefficients. */
8860 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
8862 struct induction
*tv
;
8864 if (v
->ignore
|| v
->maybe_dead
|| v
->mode
!= mode
)
8867 for (tv
= REG_IV_CLASS (ivs
, REGNO (arg
))->giv
; tv
;
8869 if (! tv
->ignore
&& ! tv
->maybe_dead
8870 && rtx_equal_p (tv
->mult_val
, v
->mult_val
)
8871 && rtx_equal_p (tv
->add_val
, v
->add_val
)
8872 && tv
->mode
== mode
)
8874 if (! biv_elimination_giv_has_0_offset (bl
->biv
, v
, insn
))
8880 /* Replace biv with its giv's reduced reg. */
8881 XEXP (x
, 1 - arg_operand
) = v
->new_reg
;
8882 /* Replace other operand with the other giv's
8884 XEXP (x
, arg_operand
) = tv
->new_reg
;
8891 /* If we get here, the biv can't be eliminated. */
8895 /* If this address is a DEST_ADDR giv, it doesn't matter if the
8896 biv is used in it, since it will be replaced. */
8897 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
8898 if (v
->giv_type
== DEST_ADDR
&& v
->location
== &XEXP (x
, 0))
8906 /* See if any subexpression fails elimination. */
8907 fmt
= GET_RTX_FORMAT (code
);
8908 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
8913 if (! maybe_eliminate_biv_1 (loop
, XEXP (x
, i
), insn
, bl
,
8914 eliminate_p
, where_bb
, where_insn
))
8919 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
8920 if (! maybe_eliminate_biv_1 (loop
, XVECEXP (x
, i
, j
), insn
, bl
,
8921 eliminate_p
, where_bb
, where_insn
))
8930 /* Return nonzero if the last use of REG
8931 is in an insn following INSN in the same basic block. */
8934 last_use_this_basic_block (reg
, insn
)
8940 n
&& GET_CODE (n
) != CODE_LABEL
&& GET_CODE (n
) != JUMP_INSN
;
8943 if (REGNO_LAST_UID (REGNO (reg
)) == INSN_UID (n
))
8949 /* Called via `note_stores' to record the initial value of a biv. Here we
8950 just record the location of the set and process it later. */
8953 record_initial (dest
, set
, data
)
8956 void *data ATTRIBUTE_UNUSED
;
8958 struct loop_ivs
*ivs
= (struct loop_ivs
*) data
;
8959 struct iv_class
*bl
;
8961 if (GET_CODE (dest
) != REG
8962 || REGNO (dest
) >= ivs
->n_regs
8963 || REG_IV_TYPE (ivs
, REGNO (dest
)) != BASIC_INDUCT
)
8966 bl
= REG_IV_CLASS (ivs
, REGNO (dest
));
8968 /* If this is the first set found, record it. */
8969 if (bl
->init_insn
== 0)
8971 bl
->init_insn
= note_insn
;
8976 /* If any of the registers in X are "old" and currently have a last use earlier
8977 than INSN, update them to have a last use of INSN. Their actual last use
8978 will be the previous insn but it will not have a valid uid_luid so we can't
8979 use it. X must be a source expression only. */
8982 update_reg_last_use (x
, insn
)
8986 /* Check for the case where INSN does not have a valid luid. In this case,
8987 there is no need to modify the regno_last_uid, as this can only happen
8988 when code is inserted after the loop_end to set a pseudo's final value,
8989 and hence this insn will never be the last use of x.
8990 ???? This comment is not correct. See for example loop_givs_reduce.
8991 This may insert an insn before another new insn. */
8992 if (GET_CODE (x
) == REG
&& REGNO (x
) < max_reg_before_loop
8993 && INSN_UID (insn
) < max_uid_for_loop
8994 && REGNO_LAST_LUID (REGNO (x
)) < INSN_LUID (insn
))
8996 REGNO_LAST_UID (REGNO (x
)) = INSN_UID (insn
);
9001 const char *fmt
= GET_RTX_FORMAT (GET_CODE (x
));
9002 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0; i
--)
9005 update_reg_last_use (XEXP (x
, i
), insn
);
9006 else if (fmt
[i
] == 'E')
9007 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
9008 update_reg_last_use (XVECEXP (x
, i
, j
), insn
);
9013 /* Given an insn INSN and condition COND, return the condition in a
9014 canonical form to simplify testing by callers. Specifically:
9016 (1) The code will always be a comparison operation (EQ, NE, GT, etc.).
9017 (2) Both operands will be machine operands; (cc0) will have been replaced.
9018 (3) If an operand is a constant, it will be the second operand.
9019 (4) (LE x const) will be replaced with (LT x <const+1>) and similarly
9020 for GE, GEU, and LEU.
9022 If the condition cannot be understood, or is an inequality floating-point
9023 comparison which needs to be reversed, 0 will be returned.
9025 If REVERSE is non-zero, then reverse the condition prior to canonizing it.
9027 If EARLIEST is non-zero, it is a pointer to a place where the earliest
9028 insn used in locating the condition was found. If a replacement test
9029 of the condition is desired, it should be placed in front of that
9030 insn and we will be sure that the inputs are still valid.
9032 If WANT_REG is non-zero, we wish the condition to be relative to that
9033 register, if possible. Therefore, do not canonicalize the condition
9037 canonicalize_condition (insn
, cond
, reverse
, earliest
, want_reg
)
9049 int reverse_code
= 0;
9050 enum machine_mode mode
;
9052 code
= GET_CODE (cond
);
9053 mode
= GET_MODE (cond
);
9054 op0
= XEXP (cond
, 0);
9055 op1
= XEXP (cond
, 1);
9058 code
= reversed_comparison_code (cond
, insn
);
9059 if (code
== UNKNOWN
)
9065 /* If we are comparing a register with zero, see if the register is set
9066 in the previous insn to a COMPARE or a comparison operation. Perform
9067 the same tests as a function of STORE_FLAG_VALUE as find_comparison_args
9070 while (GET_RTX_CLASS (code
) == '<'
9071 && op1
== CONST0_RTX (GET_MODE (op0
))
9074 /* Set non-zero when we find something of interest. */
9078 /* If comparison with cc0, import actual comparison from compare
9082 if ((prev
= prev_nonnote_insn (prev
)) == 0
9083 || GET_CODE (prev
) != INSN
9084 || (set
= single_set (prev
)) == 0
9085 || SET_DEST (set
) != cc0_rtx
)
9088 op0
= SET_SRC (set
);
9089 op1
= CONST0_RTX (GET_MODE (op0
));
9095 /* If this is a COMPARE, pick up the two things being compared. */
9096 if (GET_CODE (op0
) == COMPARE
)
9098 op1
= XEXP (op0
, 1);
9099 op0
= XEXP (op0
, 0);
9102 else if (GET_CODE (op0
) != REG
)
9105 /* Go back to the previous insn. Stop if it is not an INSN. We also
9106 stop if it isn't a single set or if it has a REG_INC note because
9107 we don't want to bother dealing with it. */
9109 if ((prev
= prev_nonnote_insn (prev
)) == 0
9110 || GET_CODE (prev
) != INSN
9111 || FIND_REG_INC_NOTE (prev
, NULL_RTX
))
9114 set
= set_of (op0
, prev
);
9117 && (GET_CODE (set
) != SET
9118 || !rtx_equal_p (SET_DEST (set
), op0
)))
9121 /* If this is setting OP0, get what it sets it to if it looks
9125 enum machine_mode inner_mode
= GET_MODE (SET_DEST (set
));
9127 /* ??? We may not combine comparisons done in a CCmode with
9128 comparisons not done in a CCmode. This is to aid targets
9129 like Alpha that have an IEEE compliant EQ instruction, and
9130 a non-IEEE compliant BEQ instruction. The use of CCmode is
9131 actually artificial, simply to prevent the combination, but
9132 should not affect other platforms.
9134 However, we must allow VOIDmode comparisons to match either
9135 CCmode or non-CCmode comparison, because some ports have
9136 modeless comparisons inside branch patterns.
9138 ??? This mode check should perhaps look more like the mode check
9139 in simplify_comparison in combine. */
9141 if ((GET_CODE (SET_SRC (set
)) == COMPARE
9144 && GET_MODE_CLASS (inner_mode
) == MODE_INT
9145 && (GET_MODE_BITSIZE (inner_mode
)
9146 <= HOST_BITS_PER_WIDE_INT
)
9147 && (STORE_FLAG_VALUE
9148 & ((HOST_WIDE_INT
) 1
9149 << (GET_MODE_BITSIZE (inner_mode
) - 1))))
9150 #ifdef FLOAT_STORE_FLAG_VALUE
9152 && GET_MODE_CLASS (inner_mode
) == MODE_FLOAT
9153 && (REAL_VALUE_NEGATIVE
9154 (FLOAT_STORE_FLAG_VALUE (inner_mode
))))
9157 && GET_RTX_CLASS (GET_CODE (SET_SRC (set
))) == '<'))
9158 && (((GET_MODE_CLASS (mode
) == MODE_CC
)
9159 == (GET_MODE_CLASS (inner_mode
) == MODE_CC
))
9160 || mode
== VOIDmode
|| inner_mode
== VOIDmode
))
9162 else if (((code
== EQ
9164 && (GET_MODE_BITSIZE (inner_mode
)
9165 <= HOST_BITS_PER_WIDE_INT
)
9166 && GET_MODE_CLASS (inner_mode
) == MODE_INT
9167 && (STORE_FLAG_VALUE
9168 & ((HOST_WIDE_INT
) 1
9169 << (GET_MODE_BITSIZE (inner_mode
) - 1))))
9170 #ifdef FLOAT_STORE_FLAG_VALUE
9172 && GET_MODE_CLASS (inner_mode
) == MODE_FLOAT
9173 && (REAL_VALUE_NEGATIVE
9174 (FLOAT_STORE_FLAG_VALUE (inner_mode
))))
9177 && GET_RTX_CLASS (GET_CODE (SET_SRC (set
))) == '<'
9178 && (((GET_MODE_CLASS (mode
) == MODE_CC
)
9179 == (GET_MODE_CLASS (inner_mode
) == MODE_CC
))
9180 || mode
== VOIDmode
|| inner_mode
== VOIDmode
))
9190 else if (reg_set_p (op0
, prev
))
9191 /* If this sets OP0, but not directly, we have to give up. */
9196 if (GET_RTX_CLASS (GET_CODE (x
)) == '<')
9197 code
= GET_CODE (x
);
9200 code
= reversed_comparison_code (x
, prev
);
9201 if (code
== UNKNOWN
)
9206 op0
= XEXP (x
, 0), op1
= XEXP (x
, 1);
9212 /* If constant is first, put it last. */
9213 if (CONSTANT_P (op0
))
9214 code
= swap_condition (code
), tem
= op0
, op0
= op1
, op1
= tem
;
9216 /* If OP0 is the result of a comparison, we weren't able to find what
9217 was really being compared, so fail. */
9218 if (GET_MODE_CLASS (GET_MODE (op0
)) == MODE_CC
)
9221 /* Canonicalize any ordered comparison with integers involving equality
9222 if we can do computations in the relevant mode and we do not
9225 if (GET_CODE (op1
) == CONST_INT
9226 && GET_MODE (op0
) != VOIDmode
9227 && GET_MODE_BITSIZE (GET_MODE (op0
)) <= HOST_BITS_PER_WIDE_INT
)
9229 HOST_WIDE_INT const_val
= INTVAL (op1
);
9230 unsigned HOST_WIDE_INT uconst_val
= const_val
;
9231 unsigned HOST_WIDE_INT max_val
9232 = (unsigned HOST_WIDE_INT
) GET_MODE_MASK (GET_MODE (op0
));
9237 if ((unsigned HOST_WIDE_INT
) const_val
!= max_val
>> 1)
9238 code
= LT
, op1
= GEN_INT (const_val
+ 1);
9241 /* When cross-compiling, const_val might be sign-extended from
9242 BITS_PER_WORD to HOST_BITS_PER_WIDE_INT */
9244 if ((HOST_WIDE_INT
) (const_val
& max_val
)
9245 != (((HOST_WIDE_INT
) 1
9246 << (GET_MODE_BITSIZE (GET_MODE (op0
)) - 1))))
9247 code
= GT
, op1
= GEN_INT (const_val
- 1);
9251 if (uconst_val
< max_val
)
9252 code
= LTU
, op1
= GEN_INT (uconst_val
+ 1);
9256 if (uconst_val
!= 0)
9257 code
= GTU
, op1
= GEN_INT (uconst_val
- 1);
9266 /* Never return CC0; return zero instead. */
9271 return gen_rtx_fmt_ee (code
, VOIDmode
, op0
, op1
);
9274 /* Given a jump insn JUMP, return the condition that will cause it to branch
9275 to its JUMP_LABEL. If the condition cannot be understood, or is an
9276 inequality floating-point comparison which needs to be reversed, 0 will
9279 If EARLIEST is non-zero, it is a pointer to a place where the earliest
9280 insn used in locating the condition was found. If a replacement test
9281 of the condition is desired, it should be placed in front of that
9282 insn and we will be sure that the inputs are still valid. */
9285 get_condition (jump
, earliest
)
9293 /* If this is not a standard conditional jump, we can't parse it. */
9294 if (GET_CODE (jump
) != JUMP_INSN
9295 || ! any_condjump_p (jump
))
9297 set
= pc_set (jump
);
9299 cond
= XEXP (SET_SRC (set
), 0);
9301 /* If this branches to JUMP_LABEL when the condition is false, reverse
9304 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
9305 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
);
9307 return canonicalize_condition (jump
, cond
, reverse
, earliest
, NULL_RTX
);
9310 /* Similar to above routine, except that we also put an invariant last
9311 unless both operands are invariants. */
9314 get_condition_for_loop (loop
, x
)
9315 const struct loop
*loop
;
9318 rtx comparison
= get_condition (x
, (rtx
*) 0);
9321 || ! loop_invariant_p (loop
, XEXP (comparison
, 0))
9322 || loop_invariant_p (loop
, XEXP (comparison
, 1)))
9325 return gen_rtx_fmt_ee (swap_condition (GET_CODE (comparison
)), VOIDmode
,
9326 XEXP (comparison
, 1), XEXP (comparison
, 0));
9329 /* Scan the function and determine whether it has indirect (computed) jumps.
9331 This is taken mostly from flow.c; similar code exists elsewhere
9332 in the compiler. It may be useful to put this into rtlanal.c. */
9334 indirect_jump_in_function_p (start
)
9339 for (insn
= start
; insn
; insn
= NEXT_INSN (insn
))
9340 if (computed_jump_p (insn
))
9346 /* Add MEM to the LOOP_MEMS array, if appropriate. See the
9347 documentation for LOOP_MEMS for the definition of `appropriate'.
9348 This function is called from prescan_loop via for_each_rtx. */
9351 insert_loop_mem (mem
, data
)
9353 void *data ATTRIBUTE_UNUSED
;
9355 struct loop_info
*loop_info
= data
;
9362 switch (GET_CODE (m
))
9368 /* We're not interested in MEMs that are only clobbered. */
9372 /* We're not interested in the MEM associated with a
9373 CONST_DOUBLE, so there's no need to traverse into this. */
9377 /* We're not interested in any MEMs that only appear in notes. */
9381 /* This is not a MEM. */
9385 /* See if we've already seen this MEM. */
9386 for (i
= 0; i
< loop_info
->mems_idx
; ++i
)
9387 if (rtx_equal_p (m
, loop_info
->mems
[i
].mem
))
9389 if (GET_MODE (m
) != GET_MODE (loop_info
->mems
[i
].mem
))
9390 /* The modes of the two memory accesses are different. If
9391 this happens, something tricky is going on, and we just
9392 don't optimize accesses to this MEM. */
9393 loop_info
->mems
[i
].optimize
= 0;
9398 /* Resize the array, if necessary. */
9399 if (loop_info
->mems_idx
== loop_info
->mems_allocated
)
9401 if (loop_info
->mems_allocated
!= 0)
9402 loop_info
->mems_allocated
*= 2;
9404 loop_info
->mems_allocated
= 32;
9406 loop_info
->mems
= (loop_mem_info
*)
9407 xrealloc (loop_info
->mems
,
9408 loop_info
->mems_allocated
* sizeof (loop_mem_info
));
9411 /* Actually insert the MEM. */
9412 loop_info
->mems
[loop_info
->mems_idx
].mem
= m
;
9413 /* We can't hoist this MEM out of the loop if it's a BLKmode MEM
9414 because we can't put it in a register. We still store it in the
9415 table, though, so that if we see the same address later, but in a
9416 non-BLK mode, we'll not think we can optimize it at that point. */
9417 loop_info
->mems
[loop_info
->mems_idx
].optimize
= (GET_MODE (m
) != BLKmode
);
9418 loop_info
->mems
[loop_info
->mems_idx
].reg
= NULL_RTX
;
9419 ++loop_info
->mems_idx
;
9425 /* Allocate REGS->ARRAY or reallocate it if it is too small.
9427 Increment REGS->ARRAY[I].SET_IN_LOOP at the index I of each
9428 register that is modified by an insn between FROM and TO. If the
9429 value of an element of REGS->array[I].SET_IN_LOOP becomes 127 or
9430 more, stop incrementing it, to avoid overflow.
9432 Store in REGS->ARRAY[I].SINGLE_USAGE the single insn in which
9433 register I is used, if it is only used once. Otherwise, it is set
9434 to 0 (for no uses) or const0_rtx for more than one use. This
9435 parameter may be zero, in which case this processing is not done.
9437 Set REGS->ARRAY[I].MAY_NOT_OPTIMIZE nonzero if we should not
9438 optimize register I. */
9441 loop_regs_scan (loop
, extra_size
)
9442 const struct loop
*loop
;
9445 struct loop_regs
*regs
= LOOP_REGS (loop
);
9447 /* last_set[n] is nonzero iff reg n has been set in the current
9448 basic block. In that case, it is the insn that last set reg n. */
9453 old_nregs
= regs
->num
;
9454 regs
->num
= max_reg_num ();
9456 /* Grow the regs array if not allocated or too small. */
9457 if (regs
->num
>= regs
->size
)
9459 regs
->size
= regs
->num
+ extra_size
;
9461 regs
->array
= (struct loop_reg
*)
9462 xrealloc (regs
->array
, regs
->size
* sizeof (*regs
->array
));
9464 /* Zero the new elements. */
9465 memset (regs
->array
+ old_nregs
, 0,
9466 (regs
->size
- old_nregs
) * sizeof (*regs
->array
));
9469 /* Clear previously scanned fields but do not clear n_times_set. */
9470 for (i
= 0; i
< old_nregs
; i
++)
9472 regs
->array
[i
].set_in_loop
= 0;
9473 regs
->array
[i
].may_not_optimize
= 0;
9474 regs
->array
[i
].single_usage
= NULL_RTX
;
9477 last_set
= (rtx
*) xcalloc (regs
->num
, sizeof (rtx
));
9479 /* Scan the loop, recording register usage. */
9480 for (insn
= loop
->top
? loop
->top
: loop
->start
; insn
!= loop
->end
;
9481 insn
= NEXT_INSN (insn
))
9485 /* Record registers that have exactly one use. */
9486 find_single_use_in_loop (regs
, insn
, PATTERN (insn
));
9488 /* Include uses in REG_EQUAL notes. */
9489 if (REG_NOTES (insn
))
9490 find_single_use_in_loop (regs
, insn
, REG_NOTES (insn
));
9492 if (GET_CODE (PATTERN (insn
)) == SET
9493 || GET_CODE (PATTERN (insn
)) == CLOBBER
)
9494 count_one_set (regs
, insn
, PATTERN (insn
), last_set
);
9495 else if (GET_CODE (PATTERN (insn
)) == PARALLEL
)
9498 for (i
= XVECLEN (PATTERN (insn
), 0) - 1; i
>= 0; i
--)
9499 count_one_set (regs
, insn
, XVECEXP (PATTERN (insn
), 0, i
),
9504 if (GET_CODE (insn
) == CODE_LABEL
|| GET_CODE (insn
) == JUMP_INSN
)
9505 memset (last_set
, 0, regs
->num
* sizeof (rtx
));
9508 /* Invalidate all hard registers clobbered by calls. With one exception:
9509 a call-clobbered PIC register is still function-invariant for our
9510 purposes, since we can hoist any PIC calculations out of the loop.
9511 Thus the call to rtx_varies_p. */
9512 if (LOOP_INFO (loop
)->has_call
)
9513 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
9514 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
)
9515 && rtx_varies_p (gen_rtx_REG (Pmode
, i
), /*for_alias=*/1))
9517 regs
->array
[i
].may_not_optimize
= 1;
9518 regs
->array
[i
].set_in_loop
= 1;
9521 #ifdef AVOID_CCMODE_COPIES
9522 /* Don't try to move insns which set CC registers if we should not
9523 create CCmode register copies. */
9524 for (i
= regs
->num
- 1; i
>= FIRST_PSEUDO_REGISTER
; i
--)
9525 if (GET_MODE_CLASS (GET_MODE (regno_reg_rtx
[i
])) == MODE_CC
)
9526 regs
->array
[i
].may_not_optimize
= 1;
9529 /* Set regs->array[I].n_times_set for the new registers. */
9530 for (i
= old_nregs
; i
< regs
->num
; i
++)
9531 regs
->array
[i
].n_times_set
= regs
->array
[i
].set_in_loop
;
9536 /* Returns the number of real INSNs in the LOOP. */
9539 count_insns_in_loop (loop
)
9540 const struct loop
*loop
;
9545 for (insn
= loop
->top
? loop
->top
: loop
->start
; insn
!= loop
->end
;
9546 insn
= NEXT_INSN (insn
))
9553 /* Move MEMs into registers for the duration of the loop. */
9557 const struct loop
*loop
;
9559 struct loop_info
*loop_info
= LOOP_INFO (loop
);
9560 struct loop_regs
*regs
= LOOP_REGS (loop
);
9561 int maybe_never
= 0;
9563 rtx p
, prev_ebb_head
;
9564 rtx label
= NULL_RTX
;
9566 /* Nonzero if the next instruction may never be executed. */
9567 int next_maybe_never
= 0;
9568 unsigned int last_max_reg
= max_reg_num ();
9570 if (loop_info
->mems_idx
== 0)
9573 /* We cannot use next_label here because it skips over normal insns. */
9574 end_label
= next_nonnote_insn (loop
->end
);
9575 if (end_label
&& GET_CODE (end_label
) != CODE_LABEL
)
9576 end_label
= NULL_RTX
;
9578 /* Check to see if it's possible that some instructions in the loop are
9579 never executed. Also check if there is a goto out of the loop other
9580 than right after the end of the loop. */
9581 for (p
= next_insn_in_loop (loop
, loop
->scan_start
);
9583 p
= next_insn_in_loop (loop
, p
))
9585 if (GET_CODE (p
) == CODE_LABEL
)
9587 else if (GET_CODE (p
) == JUMP_INSN
9588 /* If we enter the loop in the middle, and scan
9589 around to the beginning, don't set maybe_never
9590 for that. This must be an unconditional jump,
9591 otherwise the code at the top of the loop might
9592 never be executed. Unconditional jumps are
9593 followed a by barrier then loop end. */
9594 && ! (GET_CODE (p
) == JUMP_INSN
9595 && JUMP_LABEL (p
) == loop
->top
9596 && NEXT_INSN (NEXT_INSN (p
)) == loop
->end
9597 && any_uncondjump_p (p
)))
9599 /* If this is a jump outside of the loop but not right
9600 after the end of the loop, we would have to emit new fixup
9601 sequences for each such label. */
9602 if (/* If we can't tell where control might go when this
9603 JUMP_INSN is executed, we must be conservative. */
9605 || (JUMP_LABEL (p
) != end_label
9606 && (INSN_UID (JUMP_LABEL (p
)) >= max_uid_for_loop
9607 || INSN_LUID (JUMP_LABEL (p
)) < INSN_LUID (loop
->start
)
9608 || INSN_LUID (JUMP_LABEL (p
)) > INSN_LUID (loop
->end
))))
9611 if (!any_condjump_p (p
))
9612 /* Something complicated. */
9615 /* If there are any more instructions in the loop, they
9616 might not be reached. */
9617 next_maybe_never
= 1;
9619 else if (next_maybe_never
)
9623 /* Find start of the extended basic block that enters the loop. */
9624 for (p
= loop
->start
;
9625 PREV_INSN (p
) && GET_CODE (p
) != CODE_LABEL
;
9632 /* Build table of mems that get set to constant values before the
9634 for (; p
!= loop
->start
; p
= NEXT_INSN (p
))
9635 cselib_process_insn (p
);
9637 /* Actually move the MEMs. */
9638 for (i
= 0; i
< loop_info
->mems_idx
; ++i
)
9640 regset_head load_copies
;
9641 regset_head store_copies
;
9644 rtx mem
= loop_info
->mems
[i
].mem
;
9647 if (MEM_VOLATILE_P (mem
)
9648 || loop_invariant_p (loop
, XEXP (mem
, 0)) != 1)
9649 /* There's no telling whether or not MEM is modified. */
9650 loop_info
->mems
[i
].optimize
= 0;
9652 /* Go through the MEMs written to in the loop to see if this
9653 one is aliased by one of them. */
9654 mem_list_entry
= loop_info
->store_mems
;
9655 while (mem_list_entry
)
9657 if (rtx_equal_p (mem
, XEXP (mem_list_entry
, 0)))
9659 else if (true_dependence (XEXP (mem_list_entry
, 0), VOIDmode
,
9662 /* MEM is indeed aliased by this store. */
9663 loop_info
->mems
[i
].optimize
= 0;
9666 mem_list_entry
= XEXP (mem_list_entry
, 1);
9669 if (flag_float_store
&& written
9670 && GET_MODE_CLASS (GET_MODE (mem
)) == MODE_FLOAT
)
9671 loop_info
->mems
[i
].optimize
= 0;
9673 /* If this MEM is written to, we must be sure that there
9674 are no reads from another MEM that aliases this one. */
9675 if (loop_info
->mems
[i
].optimize
&& written
)
9679 for (j
= 0; j
< loop_info
->mems_idx
; ++j
)
9683 else if (true_dependence (mem
,
9685 loop_info
->mems
[j
].mem
,
9688 /* It's not safe to hoist loop_info->mems[i] out of
9689 the loop because writes to it might not be
9690 seen by reads from loop_info->mems[j]. */
9691 loop_info
->mems
[i
].optimize
= 0;
9697 if (maybe_never
&& may_trap_p (mem
))
9698 /* We can't access the MEM outside the loop; it might
9699 cause a trap that wouldn't have happened otherwise. */
9700 loop_info
->mems
[i
].optimize
= 0;
9702 if (!loop_info
->mems
[i
].optimize
)
9703 /* We thought we were going to lift this MEM out of the
9704 loop, but later discovered that we could not. */
9707 INIT_REG_SET (&load_copies
);
9708 INIT_REG_SET (&store_copies
);
9710 /* Allocate a pseudo for this MEM. We set REG_USERVAR_P in
9711 order to keep scan_loop from moving stores to this MEM
9712 out of the loop just because this REG is neither a
9713 user-variable nor used in the loop test. */
9714 reg
= gen_reg_rtx (GET_MODE (mem
));
9715 REG_USERVAR_P (reg
) = 1;
9716 loop_info
->mems
[i
].reg
= reg
;
9718 /* Now, replace all references to the MEM with the
9719 corresponding pseudos. */
9721 for (p
= next_insn_in_loop (loop
, loop
->scan_start
);
9723 p
= next_insn_in_loop (loop
, p
))
9729 set
= single_set (p
);
9731 /* See if this copies the mem into a register that isn't
9732 modified afterwards. We'll try to do copy propagation
9733 a little further on. */
9735 /* @@@ This test is _way_ too conservative. */
9737 && GET_CODE (SET_DEST (set
)) == REG
9738 && REGNO (SET_DEST (set
)) >= FIRST_PSEUDO_REGISTER
9739 && REGNO (SET_DEST (set
)) < last_max_reg
9740 && regs
->array
[REGNO (SET_DEST (set
))].n_times_set
== 1
9741 && rtx_equal_p (SET_SRC (set
), mem
))
9742 SET_REGNO_REG_SET (&load_copies
, REGNO (SET_DEST (set
)));
9744 /* See if this copies the mem from a register that isn't
9745 modified afterwards. We'll try to remove the
9746 redundant copy later on by doing a little register
9747 renaming and copy propagation. This will help
9748 to untangle things for the BIV detection code. */
9751 && GET_CODE (SET_SRC (set
)) == REG
9752 && REGNO (SET_SRC (set
)) >= FIRST_PSEUDO_REGISTER
9753 && REGNO (SET_SRC (set
)) < last_max_reg
9754 && regs
->array
[REGNO (SET_SRC (set
))].n_times_set
== 1
9755 && rtx_equal_p (SET_DEST (set
), mem
))
9756 SET_REGNO_REG_SET (&store_copies
, REGNO (SET_SRC (set
)));
9758 /* Replace the memory reference with the shadow register. */
9759 replace_loop_mems (p
, loop_info
->mems
[i
].mem
,
9760 loop_info
->mems
[i
].reg
);
9763 if (GET_CODE (p
) == CODE_LABEL
9764 || GET_CODE (p
) == JUMP_INSN
)
9768 if (! apply_change_group ())
9769 /* We couldn't replace all occurrences of the MEM. */
9770 loop_info
->mems
[i
].optimize
= 0;
9773 /* Load the memory immediately before LOOP->START, which is
9774 the NOTE_LOOP_BEG. */
9775 cselib_val
*e
= cselib_lookup (mem
, VOIDmode
, 0);
9779 struct elt_loc_list
*const_equiv
= 0;
9783 struct elt_loc_list
*equiv
;
9784 struct elt_loc_list
*best_equiv
= 0;
9785 for (equiv
= e
->locs
; equiv
; equiv
= equiv
->next
)
9787 if (CONSTANT_P (equiv
->loc
))
9788 const_equiv
= equiv
;
9789 else if (GET_CODE (equiv
->loc
) == REG
9790 /* Extending hard register lifetimes causes crash
9791 on SRC targets. Doing so on non-SRC is
9792 probably also not good idea, since we most
9793 probably have pseudoregister equivalence as
9795 && REGNO (equiv
->loc
) >= FIRST_PSEUDO_REGISTER
)
9798 /* Use the constant equivalence if that is cheap enough. */
9800 best_equiv
= const_equiv
;
9801 else if (const_equiv
9802 && (rtx_cost (const_equiv
->loc
, SET
)
9803 <= rtx_cost (best_equiv
->loc
, SET
)))
9805 best_equiv
= const_equiv
;
9809 /* If best_equiv is nonzero, we know that MEM is set to a
9810 constant or register before the loop. We will use this
9811 knowledge to initialize the shadow register with that
9812 constant or reg rather than by loading from MEM. */
9814 best
= copy_rtx (best_equiv
->loc
);
9817 set
= gen_move_insn (reg
, best
);
9818 set
= loop_insn_hoist (loop
, set
);
9821 for (p
= prev_ebb_head
; p
!= loop
->start
; p
= NEXT_INSN (p
))
9822 if (REGNO_LAST_UID (REGNO (best
)) == INSN_UID (p
))
9824 REGNO_LAST_UID (REGNO (best
)) = INSN_UID (set
);
9830 set_unique_reg_note (set
, REG_EQUAL
, copy_rtx (const_equiv
->loc
));
9834 if (label
== NULL_RTX
)
9836 label
= gen_label_rtx ();
9837 emit_label_after (label
, loop
->end
);
9840 /* Store the memory immediately after END, which is
9841 the NOTE_LOOP_END. */
9842 set
= gen_move_insn (copy_rtx (mem
), reg
);
9843 loop_insn_emit_after (loop
, 0, label
, set
);
9846 if (loop_dump_stream
)
9848 fprintf (loop_dump_stream
, "Hoisted regno %d %s from ",
9849 REGNO (reg
), (written
? "r/w" : "r/o"));
9850 print_rtl (loop_dump_stream
, mem
);
9851 fputc ('\n', loop_dump_stream
);
9854 /* Attempt a bit of copy propagation. This helps untangle the
9855 data flow, and enables {basic,general}_induction_var to find
9857 EXECUTE_IF_SET_IN_REG_SET
9858 (&load_copies
, FIRST_PSEUDO_REGISTER
, j
,
9860 try_copy_prop (loop
, reg
, j
);
9862 CLEAR_REG_SET (&load_copies
);
9864 EXECUTE_IF_SET_IN_REG_SET
9865 (&store_copies
, FIRST_PSEUDO_REGISTER
, j
,
9867 try_swap_copy_prop (loop
, reg
, j
);
9869 CLEAR_REG_SET (&store_copies
);
9873 if (label
!= NULL_RTX
&& end_label
!= NULL_RTX
)
9875 /* Now, we need to replace all references to the previous exit
9876 label with the new one. */
9881 for (p
= loop
->start
; p
!= loop
->end
; p
= NEXT_INSN (p
))
9883 for_each_rtx (&p
, replace_label
, &rr
);
9885 /* If this is a JUMP_INSN, then we also need to fix the JUMP_LABEL
9886 field. This is not handled by for_each_rtx because it doesn't
9887 handle unprinted ('0') fields. We need to update JUMP_LABEL
9888 because the immediately following unroll pass will use it.
9889 replace_label would not work anyways, because that only handles
9891 if (GET_CODE (p
) == JUMP_INSN
&& JUMP_LABEL (p
) == end_label
)
9892 JUMP_LABEL (p
) = label
;
9899 /* For communication between note_reg_stored and its caller. */
9900 struct note_reg_stored_arg
9906 /* Called via note_stores, record in SET_SEEN whether X, which is written,
9909 note_reg_stored (x
, setter
, arg
)
9910 rtx x
, setter ATTRIBUTE_UNUSED
;
9913 struct note_reg_stored_arg
*t
= (struct note_reg_stored_arg
*) arg
;
9918 /* Try to replace every occurrence of pseudo REGNO with REPLACEMENT.
9919 There must be exactly one insn that sets this pseudo; it will be
9920 deleted if all replacements succeed and we can prove that the register
9921 is not used after the loop. */
9924 try_copy_prop (loop
, replacement
, regno
)
9925 const struct loop
*loop
;
9929 /* This is the reg that we are copying from. */
9930 rtx reg_rtx
= regno_reg_rtx
[regno
];
9933 /* These help keep track of whether we replaced all uses of the reg. */
9934 int replaced_last
= 0;
9935 int store_is_first
= 0;
9937 for (insn
= next_insn_in_loop (loop
, loop
->scan_start
);
9939 insn
= next_insn_in_loop (loop
, insn
))
9943 /* Only substitute within one extended basic block from the initializing
9945 if (GET_CODE (insn
) == CODE_LABEL
&& init_insn
)
9948 if (! INSN_P (insn
))
9951 /* Is this the initializing insn? */
9952 set
= single_set (insn
);
9954 && GET_CODE (SET_DEST (set
)) == REG
9955 && REGNO (SET_DEST (set
)) == regno
)
9961 if (REGNO_FIRST_UID (regno
) == INSN_UID (insn
))
9965 /* Only substitute after seeing the initializing insn. */
9966 if (init_insn
&& insn
!= init_insn
)
9968 struct note_reg_stored_arg arg
;
9970 replace_loop_regs (insn
, reg_rtx
, replacement
);
9971 if (REGNO_LAST_UID (regno
) == INSN_UID (insn
))
9974 /* Stop replacing when REPLACEMENT is modified. */
9975 arg
.reg
= replacement
;
9977 note_stores (PATTERN (insn
), note_reg_stored
, &arg
);
9980 rtx note
= find_reg_note (insn
, REG_EQUAL
, NULL
);
9982 /* It is possible that we've turned previously valid REG_EQUAL to
9983 invalid, as we change the REGNO to REPLACEMENT and unlike REGNO,
9984 REPLACEMENT is modified, we get different meaning. */
9985 if (note
&& reg_mentioned_p (replacement
, XEXP (note
, 0)))
9986 remove_note (insn
, note
);
9993 if (apply_change_group ())
9995 if (loop_dump_stream
)
9996 fprintf (loop_dump_stream
, " Replaced reg %d", regno
);
9997 if (store_is_first
&& replaced_last
)
10002 /* Assume we're just deleting INIT_INSN. */
10004 /* Look for REG_RETVAL note. If we're deleting the end of
10005 the libcall sequence, the whole sequence can go. */
10006 retval_note
= find_reg_note (init_insn
, REG_RETVAL
, NULL_RTX
);
10007 /* If we found a REG_RETVAL note, find the first instruction
10008 in the sequence. */
10010 first
= XEXP (retval_note
, 0);
10012 /* Delete the instructions. */
10013 loop_delete_insns (first
, init_insn
);
10015 if (loop_dump_stream
)
10016 fprintf (loop_dump_stream
, ".\n");
10020 /* Replace all the instructions from FIRST up to and including LAST
10021 with NOTE_INSN_DELETED notes. */
10024 loop_delete_insns (first
, last
)
10030 if (loop_dump_stream
)
10031 fprintf (loop_dump_stream
, ", deleting init_insn (%d)",
10033 delete_insn (first
);
10035 /* If this was the LAST instructions we're supposed to delete,
10040 first
= NEXT_INSN (first
);
10044 /* Try to replace occurrences of pseudo REGNO with REPLACEMENT within
10045 loop LOOP if the order of the sets of these registers can be
10046 swapped. There must be exactly one insn within the loop that sets
10047 this pseudo followed immediately by a move insn that sets
10048 REPLACEMENT with REGNO. */
10050 try_swap_copy_prop (loop
, replacement
, regno
)
10051 const struct loop
*loop
;
10053 unsigned int regno
;
10056 rtx set
= NULL_RTX
;
10057 unsigned int new_regno
;
10059 new_regno
= REGNO (replacement
);
10061 for (insn
= next_insn_in_loop (loop
, loop
->scan_start
);
10063 insn
= next_insn_in_loop (loop
, insn
))
10065 /* Search for the insn that copies REGNO to NEW_REGNO? */
10067 && (set
= single_set (insn
))
10068 && GET_CODE (SET_DEST (set
)) == REG
10069 && REGNO (SET_DEST (set
)) == new_regno
10070 && GET_CODE (SET_SRC (set
)) == REG
10071 && REGNO (SET_SRC (set
)) == regno
)
10075 if (insn
!= NULL_RTX
)
10080 /* Some DEF-USE info would come in handy here to make this
10081 function more general. For now, just check the previous insn
10082 which is the most likely candidate for setting REGNO. */
10084 prev_insn
= PREV_INSN (insn
);
10087 && (prev_set
= single_set (prev_insn
))
10088 && GET_CODE (SET_DEST (prev_set
)) == REG
10089 && REGNO (SET_DEST (prev_set
)) == regno
)
10092 (set (reg regno) (expr))
10093 (set (reg new_regno) (reg regno))
10095 so try converting this to:
10096 (set (reg new_regno) (expr))
10097 (set (reg regno) (reg new_regno))
10099 The former construct is often generated when a global
10100 variable used for an induction variable is shadowed by a
10101 register (NEW_REGNO). The latter construct improves the
10102 chances of GIV replacement and BIV elimination. */
10104 validate_change (prev_insn
, &SET_DEST (prev_set
),
10106 validate_change (insn
, &SET_DEST (set
),
10108 validate_change (insn
, &SET_SRC (set
),
10111 if (apply_change_group ())
10113 if (loop_dump_stream
)
10114 fprintf (loop_dump_stream
,
10115 " Swapped set of reg %d at %d with reg %d at %d.\n",
10116 regno
, INSN_UID (insn
),
10117 new_regno
, INSN_UID (prev_insn
));
10119 /* Update first use of REGNO. */
10120 if (REGNO_FIRST_UID (regno
) == INSN_UID (prev_insn
))
10121 REGNO_FIRST_UID (regno
) = INSN_UID (insn
);
10123 /* Now perform copy propagation to hopefully
10124 remove all uses of REGNO within the loop. */
10125 try_copy_prop (loop
, replacement
, regno
);
10131 /* Replace MEM with its associated pseudo register. This function is
10132 called from load_mems via for_each_rtx. DATA is actually a pointer
10133 to a structure describing the instruction currently being scanned
10134 and the MEM we are currently replacing. */
10137 replace_loop_mem (mem
, data
)
10141 loop_replace_args
*args
= (loop_replace_args
*) data
;
10147 switch (GET_CODE (m
))
10153 /* We're not interested in the MEM associated with a
10154 CONST_DOUBLE, so there's no need to traverse into one. */
10158 /* This is not a MEM. */
10162 if (!rtx_equal_p (args
->match
, m
))
10163 /* This is not the MEM we are currently replacing. */
10166 /* Actually replace the MEM. */
10167 validate_change (args
->insn
, mem
, args
->replacement
, 1);
10173 replace_loop_mems (insn
, mem
, reg
)
10178 loop_replace_args args
;
10182 args
.replacement
= reg
;
10184 for_each_rtx (&insn
, replace_loop_mem
, &args
);
10187 /* Replace one register with another. Called through for_each_rtx; PX points
10188 to the rtx being scanned. DATA is actually a pointer to
10189 a structure of arguments. */
10192 replace_loop_reg (px
, data
)
10197 loop_replace_args
*args
= (loop_replace_args
*) data
;
10202 if (x
== args
->match
)
10203 validate_change (args
->insn
, px
, args
->replacement
, 1);
10209 replace_loop_regs (insn
, reg
, replacement
)
10214 loop_replace_args args
;
10218 args
.replacement
= replacement
;
10220 for_each_rtx (&insn
, replace_loop_reg
, &args
);
10223 /* Replace occurrences of the old exit label for the loop with the new
10224 one. DATA is an rtx_pair containing the old and new labels,
10228 replace_label (x
, data
)
10233 rtx old_label
= ((rtx_pair
*) data
)->r1
;
10234 rtx new_label
= ((rtx_pair
*) data
)->r2
;
10239 if (GET_CODE (l
) != LABEL_REF
)
10242 if (XEXP (l
, 0) != old_label
)
10245 XEXP (l
, 0) = new_label
;
10246 ++LABEL_NUSES (new_label
);
10247 --LABEL_NUSES (old_label
);
10252 /* Emit insn for PATTERN after WHERE_INSN in basic block WHERE_BB
10253 (ignored in the interim). */
10256 loop_insn_emit_after (loop
, where_bb
, where_insn
, pattern
)
10257 const struct loop
*loop ATTRIBUTE_UNUSED
;
10258 basic_block where_bb ATTRIBUTE_UNUSED
;
10262 return emit_insn_after (pattern
, where_insn
);
10266 /* If WHERE_INSN is non-zero emit insn for PATTERN before WHERE_INSN
10267 in basic block WHERE_BB (ignored in the interim) within the loop
10268 otherwise hoist PATTERN into the loop pre-header. */
10271 loop_insn_emit_before (loop
, where_bb
, where_insn
, pattern
)
10272 const struct loop
*loop
;
10273 basic_block where_bb ATTRIBUTE_UNUSED
;
10278 return loop_insn_hoist (loop
, pattern
);
10279 return emit_insn_before (pattern
, where_insn
);
10283 /* Emit call insn for PATTERN before WHERE_INSN in basic block
10284 WHERE_BB (ignored in the interim) within the loop. */
10287 loop_call_insn_emit_before (loop
, where_bb
, where_insn
, pattern
)
10288 const struct loop
*loop ATTRIBUTE_UNUSED
;
10289 basic_block where_bb ATTRIBUTE_UNUSED
;
10293 return emit_call_insn_before (pattern
, where_insn
);
10297 /* Hoist insn for PATTERN into the loop pre-header. */
10300 loop_insn_hoist (loop
, pattern
)
10301 const struct loop
*loop
;
10304 return loop_insn_emit_before (loop
, 0, loop
->start
, pattern
);
10308 /* Hoist call insn for PATTERN into the loop pre-header. */
10311 loop_call_insn_hoist (loop
, pattern
)
10312 const struct loop
*loop
;
10315 return loop_call_insn_emit_before (loop
, 0, loop
->start
, pattern
);
10319 /* Sink insn for PATTERN after the loop end. */
10322 loop_insn_sink (loop
, pattern
)
10323 const struct loop
*loop
;
10326 return loop_insn_emit_before (loop
, 0, loop
->sink
, pattern
);
10330 /* If the loop has multiple exits, emit insn for PATTERN before the
10331 loop to ensure that it will always be executed no matter how the
10332 loop exits. Otherwise, emit the insn for PATTERN after the loop,
10333 since this is slightly more efficient. */
10336 loop_insn_sink_or_swim (loop
, pattern
)
10337 const struct loop
*loop
;
10340 if (loop
->exit_count
)
10341 return loop_insn_hoist (loop
, pattern
);
10343 return loop_insn_sink (loop
, pattern
);
10347 loop_ivs_dump (loop
, file
, verbose
)
10348 const struct loop
*loop
;
10352 struct iv_class
*bl
;
10355 if (! loop
|| ! file
)
10358 for (bl
= LOOP_IVS (loop
)->list
; bl
; bl
= bl
->next
)
10361 fprintf (file
, "Loop %d: %d IV classes\n", loop
->num
, iv_num
);
10363 for (bl
= LOOP_IVS (loop
)->list
; bl
; bl
= bl
->next
)
10365 loop_iv_class_dump (bl
, file
, verbose
);
10366 fputc ('\n', file
);
10372 loop_iv_class_dump (bl
, file
, verbose
)
10373 const struct iv_class
*bl
;
10375 int verbose ATTRIBUTE_UNUSED
;
10377 struct induction
*v
;
10381 if (! bl
|| ! file
)
10384 fprintf (file
, "IV class for reg %d, benefit %d\n",
10385 bl
->regno
, bl
->total_benefit
);
10387 fprintf (file
, " Init insn %d", INSN_UID (bl
->init_insn
));
10388 if (bl
->initial_value
)
10390 fprintf (file
, ", init val: ");
10391 print_simple_rtl (file
, bl
->initial_value
);
10393 if (bl
->initial_test
)
10395 fprintf (file
, ", init test: ");
10396 print_simple_rtl (file
, bl
->initial_test
);
10398 fputc ('\n', file
);
10400 if (bl
->final_value
)
10402 fprintf (file
, " Final val: ");
10403 print_simple_rtl (file
, bl
->final_value
);
10404 fputc ('\n', file
);
10407 if ((incr
= biv_total_increment (bl
)))
10409 fprintf (file
, " Total increment: ");
10410 print_simple_rtl (file
, incr
);
10411 fputc ('\n', file
);
10414 /* List the increments. */
10415 for (i
= 0, v
= bl
->biv
; v
; v
= v
->next_iv
, i
++)
10417 fprintf (file
, " Inc%d: insn %d, incr: ", i
, INSN_UID (v
->insn
));
10418 print_simple_rtl (file
, v
->add_val
);
10419 fputc ('\n', file
);
10422 /* List the givs. */
10423 for (i
= 0, v
= bl
->giv
; v
; v
= v
->next_iv
, i
++)
10425 fprintf (file
, " Giv%d: insn %d, benefit %d, ",
10426 i
, INSN_UID (v
->insn
), v
->benefit
);
10427 if (v
->giv_type
== DEST_ADDR
)
10428 print_simple_rtl (file
, v
->mem
);
10430 print_simple_rtl (file
, single_set (v
->insn
));
10431 fputc ('\n', file
);
10437 loop_biv_dump (v
, file
, verbose
)
10438 const struct induction
*v
;
10447 REGNO (v
->dest_reg
), INSN_UID (v
->insn
));
10448 fprintf (file
, " const ");
10449 print_simple_rtl (file
, v
->add_val
);
10451 if (verbose
&& v
->final_value
)
10453 fputc ('\n', file
);
10454 fprintf (file
, " final ");
10455 print_simple_rtl (file
, v
->final_value
);
10458 fputc ('\n', file
);
10463 loop_giv_dump (v
, file
, verbose
)
10464 const struct induction
*v
;
10471 if (v
->giv_type
== DEST_REG
)
10472 fprintf (file
, "Giv %d: insn %d",
10473 REGNO (v
->dest_reg
), INSN_UID (v
->insn
));
10475 fprintf (file
, "Dest address: insn %d",
10476 INSN_UID (v
->insn
));
10478 fprintf (file
, " src reg %d benefit %d",
10479 REGNO (v
->src_reg
), v
->benefit
);
10480 fprintf (file
, " lifetime %d",
10483 if (v
->replaceable
)
10484 fprintf (file
, " replaceable");
10486 if (v
->no_const_addval
)
10487 fprintf (file
, " ncav");
10489 if (v
->ext_dependent
)
10491 switch (GET_CODE (v
->ext_dependent
))
10494 fprintf (file
, " ext se");
10497 fprintf (file
, " ext ze");
10500 fprintf (file
, " ext tr");
10507 fputc ('\n', file
);
10508 fprintf (file
, " mult ");
10509 print_simple_rtl (file
, v
->mult_val
);
10511 fputc ('\n', file
);
10512 fprintf (file
, " add ");
10513 print_simple_rtl (file
, v
->add_val
);
10515 if (verbose
&& v
->final_value
)
10517 fputc ('\n', file
);
10518 fprintf (file
, " final ");
10519 print_simple_rtl (file
, v
->final_value
);
10522 fputc ('\n', file
);
10528 const struct loop
*loop
;
10530 loop_ivs_dump (loop
, stderr
, 1);
10535 debug_iv_class (bl
)
10536 const struct iv_class
*bl
;
10538 loop_iv_class_dump (bl
, stderr
, 1);
10544 const struct induction
*v
;
10546 loop_biv_dump (v
, stderr
, 1);
10552 const struct induction
*v
;
10554 loop_giv_dump (v
, stderr
, 1);
10558 #define LOOP_BLOCK_NUM_1(INSN) \
10559 ((INSN) ? (BLOCK_FOR_INSN (INSN) ? BLOCK_NUM (INSN) : - 1) : -1)
10561 /* The notes do not have an assigned block, so look at the next insn. */
10562 #define LOOP_BLOCK_NUM(INSN) \
10563 ((INSN) ? (GET_CODE (INSN) == NOTE \
10564 ? LOOP_BLOCK_NUM_1 (next_nonnote_insn (INSN)) \
10565 : LOOP_BLOCK_NUM_1 (INSN)) \
10568 #define LOOP_INSN_UID(INSN) ((INSN) ? INSN_UID (INSN) : -1)
10571 loop_dump_aux (loop
, file
, verbose
)
10572 const struct loop
*loop
;
10574 int verbose ATTRIBUTE_UNUSED
;
10578 if (! loop
|| ! file
)
10581 /* Print diagnostics to compare our concept of a loop with
10582 what the loop notes say. */
10583 if (! PREV_INSN (loop
->first
->head
)
10584 || GET_CODE (PREV_INSN (loop
->first
->head
)) != NOTE
10585 || NOTE_LINE_NUMBER (PREV_INSN (loop
->first
->head
))
10586 != NOTE_INSN_LOOP_BEG
)
10587 fprintf (file
, ";; No NOTE_INSN_LOOP_BEG at %d\n",
10588 INSN_UID (PREV_INSN (loop
->first
->head
)));
10589 if (! NEXT_INSN (loop
->last
->end
)
10590 || GET_CODE (NEXT_INSN (loop
->last
->end
)) != NOTE
10591 || NOTE_LINE_NUMBER (NEXT_INSN (loop
->last
->end
))
10592 != NOTE_INSN_LOOP_END
)
10593 fprintf (file
, ";; No NOTE_INSN_LOOP_END at %d\n",
10594 INSN_UID (NEXT_INSN (loop
->last
->end
)));
10599 ";; start %d (%d), cont dom %d (%d), cont %d (%d), vtop %d (%d), end %d (%d)\n",
10600 LOOP_BLOCK_NUM (loop
->start
),
10601 LOOP_INSN_UID (loop
->start
),
10602 LOOP_BLOCK_NUM (loop
->cont
),
10603 LOOP_INSN_UID (loop
->cont
),
10604 LOOP_BLOCK_NUM (loop
->cont
),
10605 LOOP_INSN_UID (loop
->cont
),
10606 LOOP_BLOCK_NUM (loop
->vtop
),
10607 LOOP_INSN_UID (loop
->vtop
),
10608 LOOP_BLOCK_NUM (loop
->end
),
10609 LOOP_INSN_UID (loop
->end
));
10610 fprintf (file
, ";; top %d (%d), scan start %d (%d)\n",
10611 LOOP_BLOCK_NUM (loop
->top
),
10612 LOOP_INSN_UID (loop
->top
),
10613 LOOP_BLOCK_NUM (loop
->scan_start
),
10614 LOOP_INSN_UID (loop
->scan_start
));
10615 fprintf (file
, ";; exit_count %d", loop
->exit_count
);
10616 if (loop
->exit_count
)
10618 fputs (", labels:", file
);
10619 for (label
= loop
->exit_labels
; label
; label
= LABEL_NEXTREF (label
))
10621 fprintf (file
, " %d ",
10622 LOOP_INSN_UID (XEXP (label
, 0)));
10625 fputs ("\n", file
);
10627 /* This can happen when a marked loop appears as two nested loops,
10628 say from while (a || b) {}. The inner loop won't match
10629 the loop markers but the outer one will. */
10630 if (LOOP_BLOCK_NUM (loop
->cont
) != loop
->latch
->index
)
10631 fprintf (file
, ";; NOTE_INSN_LOOP_CONT not in loop latch\n");
10635 /* Call this function from the debugger to dump LOOP. */
10639 const struct loop
*loop
;
10641 flow_loop_dump (loop
, stderr
, loop_dump_aux
, 1);
10644 /* Call this function from the debugger to dump LOOPS. */
10647 debug_loops (loops
)
10648 const struct loops
*loops
;
10650 flow_loops_dump (loops
, stderr
, loop_dump_aux
, 1);