1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003 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 file contains the data flow analysis pass of the compiler. It
23 computes data flow information which tells combine_instructions
24 which insns to consider combining and controls register allocation.
26 Additional data flow information that is too bulky to record is
27 generated during the analysis, and is used at that time to create
28 autoincrement and autodecrement addressing.
30 The first step is dividing the function into basic blocks.
31 find_basic_blocks does this. Then life_analysis determines
32 where each register is live and where it is dead.
34 ** find_basic_blocks **
36 find_basic_blocks divides the current function's rtl into basic
37 blocks and constructs the CFG. The blocks are recorded in the
38 basic_block_info array; the CFG exists in the edge structures
39 referenced by the blocks.
41 find_basic_blocks also finds any unreachable loops and deletes them.
45 life_analysis is called immediately after find_basic_blocks.
46 It uses the basic block information to determine where each
47 hard or pseudo register is live.
49 ** live-register info **
51 The information about where each register is live is in two parts:
52 the REG_NOTES of insns, and the vector basic_block->global_live_at_start.
54 basic_block->global_live_at_start has an element for each basic
55 block, and the element is a bit-vector with a bit for each hard or
56 pseudo register. The bit is 1 if the register is live at the
57 beginning of the basic block.
59 Two types of elements can be added to an insn's REG_NOTES.
60 A REG_DEAD note is added to an insn's REG_NOTES for any register
61 that meets both of two conditions: The value in the register is not
62 needed in subsequent insns and the insn does not replace the value in
63 the register (in the case of multi-word hard registers, the value in
64 each register must be replaced by the insn to avoid a REG_DEAD note).
66 In the vast majority of cases, an object in a REG_DEAD note will be
67 used somewhere in the insn. The (rare) exception to this is if an
68 insn uses a multi-word hard register and only some of the registers are
69 needed in subsequent insns. In that case, REG_DEAD notes will be
70 provided for those hard registers that are not subsequently needed.
71 Partial REG_DEAD notes of this type do not occur when an insn sets
72 only some of the hard registers used in such a multi-word operand;
73 omitting REG_DEAD notes for objects stored in an insn is optional and
74 the desire to do so does not justify the complexity of the partial
77 REG_UNUSED notes are added for each register that is set by the insn
78 but is unused subsequently (if every register set by the insn is unused
79 and the insn does not reference memory or have some other side-effect,
80 the insn is deleted instead). If only part of a multi-word hard
81 register is used in a subsequent insn, REG_UNUSED notes are made for
82 the parts that will not be used.
84 To determine which registers are live after any insn, one can
85 start from the beginning of the basic block and scan insns, noting
86 which registers are set by each insn and which die there.
88 ** Other actions of life_analysis **
90 life_analysis sets up the LOG_LINKS fields of insns because the
91 information needed to do so is readily available.
93 life_analysis deletes insns whose only effect is to store a value
96 life_analysis notices cases where a reference to a register as
97 a memory address can be combined with a preceding or following
98 incrementation or decrementation of the register. The separate
99 instruction to increment or decrement is deleted and the address
100 is changed to a POST_INC or similar rtx.
102 Each time an incrementing or decrementing address is created,
103 a REG_INC element is added to the insn's REG_NOTES list.
105 life_analysis fills in certain vectors containing information about
106 register usage: REG_N_REFS, REG_N_DEATHS, REG_N_SETS, REG_LIVE_LENGTH,
107 REG_N_CALLS_CROSSED and REG_BASIC_BLOCK.
109 life_analysis sets current_function_sp_is_unchanging if the function
110 doesn't modify the stack pointer. */
114 Split out from life_analysis:
115 - local property discovery (bb->local_live, bb->local_set)
116 - global property computation
118 - pre/post modify transformation
123 #include "coretypes.h"
128 #include "hard-reg-set.h"
129 #include "basic-block.h"
130 #include "insn-config.h"
134 #include "function.h"
142 #include "splay-tree.h"
144 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
145 the stack pointer does not matter. The value is tested only in
146 functions that have frame pointers.
147 No definition is equivalent to always zero. */
148 #ifndef EXIT_IGNORE_STACK
149 #define EXIT_IGNORE_STACK 0
152 #ifndef HAVE_epilogue
153 #define HAVE_epilogue 0
155 #ifndef HAVE_prologue
156 #define HAVE_prologue 0
158 #ifndef HAVE_sibcall_epilogue
159 #define HAVE_sibcall_epilogue 0
163 #define LOCAL_REGNO(REGNO) 0
165 #ifndef EPILOGUE_USES
166 #define EPILOGUE_USES(REGNO) 0
169 #define EH_USES(REGNO) 0
172 #ifdef HAVE_conditional_execution
173 #ifndef REVERSE_CONDEXEC_PREDICATES_P
174 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y))
178 /* Nonzero if the second flow pass has completed. */
181 /* Maximum register number used in this function, plus one. */
185 /* Indexed by n, giving various register information */
187 varray_type reg_n_info
;
189 /* Size of a regset for the current function,
190 in (1) bytes and (2) elements. */
195 /* Regset of regs live when calls to `setjmp'-like functions happen. */
196 /* ??? Does this exist only for the setjmp-clobbered warning message? */
198 regset regs_live_at_setjmp
;
200 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
201 that have to go in the same hard reg.
202 The first two regs in the list are a pair, and the next two
203 are another pair, etc. */
206 /* Callback that determines if it's ok for a function to have no
207 noreturn attribute. */
208 int (*lang_missing_noreturn_ok_p
) (tree
);
210 /* Set of registers that may be eliminable. These are handled specially
211 in updating regs_ever_live. */
213 static HARD_REG_SET elim_reg_set
;
215 /* Holds information for tracking conditional register life information. */
216 struct reg_cond_life_info
218 /* A boolean expression of conditions under which a register is dead. */
220 /* Conditions under which a register is dead at the basic block end. */
223 /* A boolean expression of conditions under which a register has been
227 /* ??? Could store mask of bytes that are dead, so that we could finally
228 track lifetimes of multi-word registers accessed via subregs. */
231 /* For use in communicating between propagate_block and its subroutines.
232 Holds all information needed to compute life and def-use information. */
234 struct propagate_block_info
236 /* The basic block we're considering. */
239 /* Bit N is set if register N is conditionally or unconditionally live. */
242 /* Bit N is set if register N is set this insn. */
245 /* Element N is the next insn that uses (hard or pseudo) register N
246 within the current basic block; or zero, if there is no such insn. */
249 /* Contains a list of all the MEMs we are tracking for dead store
253 /* If non-null, record the set of registers set unconditionally in the
257 /* If non-null, record the set of registers set conditionally in the
259 regset cond_local_set
;
261 #ifdef HAVE_conditional_execution
262 /* Indexed by register number, holds a reg_cond_life_info for each
263 register that is not unconditionally live or dead. */
264 splay_tree reg_cond_dead
;
266 /* Bit N is set if register N is in an expression in reg_cond_dead. */
270 /* The length of mem_set_list. */
271 int mem_set_list_len
;
273 /* Nonzero if the value of CC0 is live. */
276 /* Flags controlling the set of information propagate_block collects. */
280 /* Number of dead insns removed. */
283 /* Maximum length of pbi->mem_set_list before we start dropping
284 new elements on the floor. */
285 #define MAX_MEM_SET_LIST_LEN 100
287 /* Forward declarations */
288 static int verify_wide_reg_1 (rtx
*, void *);
289 static void verify_wide_reg (int, basic_block
);
290 static void verify_local_live_at_start (regset
, basic_block
);
291 static void notice_stack_pointer_modification_1 (rtx
, rtx
, void *);
292 static void notice_stack_pointer_modification (rtx
);
293 static void mark_reg (rtx
, void *);
294 static void mark_regs_live_at_end (regset
);
295 static void calculate_global_regs_live (sbitmap
, sbitmap
, int);
296 static void propagate_block_delete_insn (rtx
);
297 static rtx
propagate_block_delete_libcall (rtx
, rtx
);
298 static int insn_dead_p (struct propagate_block_info
*, rtx
, int, rtx
);
299 static int libcall_dead_p (struct propagate_block_info
*, rtx
, rtx
);
300 static void mark_set_regs (struct propagate_block_info
*, rtx
, rtx
);
301 static void mark_set_1 (struct propagate_block_info
*, enum rtx_code
, rtx
,
303 static int find_regno_partial (rtx
*, void *);
305 #ifdef HAVE_conditional_execution
306 static int mark_regno_cond_dead (struct propagate_block_info
*, int, rtx
);
307 static void free_reg_cond_life_info (splay_tree_value
);
308 static int flush_reg_cond_reg_1 (splay_tree_node
, void *);
309 static void flush_reg_cond_reg (struct propagate_block_info
*, int);
310 static rtx
elim_reg_cond (rtx
, unsigned int);
311 static rtx
ior_reg_cond (rtx
, rtx
, int);
312 static rtx
not_reg_cond (rtx
);
313 static rtx
and_reg_cond (rtx
, rtx
, int);
316 static void attempt_auto_inc (struct propagate_block_info
*, rtx
, rtx
, rtx
,
318 static void find_auto_inc (struct propagate_block_info
*, rtx
, rtx
);
319 static int try_pre_increment_1 (struct propagate_block_info
*, rtx
);
320 static int try_pre_increment (rtx
, rtx
, HOST_WIDE_INT
);
322 static void mark_used_reg (struct propagate_block_info
*, rtx
, rtx
, rtx
);
323 static void mark_used_regs (struct propagate_block_info
*, rtx
, rtx
, rtx
);
324 void debug_flow_info (void);
325 static void add_to_mem_set_list (struct propagate_block_info
*, rtx
);
326 static int invalidate_mems_from_autoinc (rtx
*, void *);
327 static void invalidate_mems_from_set (struct propagate_block_info
*, rtx
);
328 static void clear_log_links (sbitmap
);
329 static int count_or_remove_death_notes_bb (basic_block
, int);
333 check_function_return_warnings (void)
335 if (warn_missing_noreturn
336 && !TREE_THIS_VOLATILE (cfun
->decl
)
337 && EXIT_BLOCK_PTR
->pred
== NULL
338 && (lang_missing_noreturn_ok_p
339 && !lang_missing_noreturn_ok_p (cfun
->decl
)))
340 warning ("function might be possible candidate for attribute `noreturn'");
342 /* If we have a path to EXIT, then we do return. */
343 if (TREE_THIS_VOLATILE (cfun
->decl
)
344 && EXIT_BLOCK_PTR
->pred
!= NULL
)
345 warning ("`noreturn' function does return");
347 /* If the clobber_return_insn appears in some basic block, then we
348 do reach the end without returning a value. */
349 else if (warn_return_type
350 && cfun
->x_clobber_return_insn
!= NULL
351 && EXIT_BLOCK_PTR
->pred
!= NULL
)
353 int max_uid
= get_max_uid ();
355 /* If clobber_return_insn was excised by jump1, then renumber_insns
356 can make max_uid smaller than the number still recorded in our rtx.
357 That's fine, since this is a quick way of verifying that the insn
358 is no longer in the chain. */
359 if (INSN_UID (cfun
->x_clobber_return_insn
) < max_uid
)
363 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
364 if (insn
== cfun
->x_clobber_return_insn
)
366 warning ("control reaches end of non-void function");
373 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
374 note associated with the BLOCK. */
377 first_insn_after_basic_block_note (basic_block block
)
381 /* Get the first instruction in the block. */
384 if (insn
== NULL_RTX
)
386 if (GET_CODE (insn
) == CODE_LABEL
)
387 insn
= NEXT_INSN (insn
);
388 if (!NOTE_INSN_BASIC_BLOCK_P (insn
))
391 return NEXT_INSN (insn
);
394 /* Perform data flow analysis.
395 F is the first insn of the function; FLAGS is a set of PROP_* flags
396 to be used in accumulating flow info. */
399 life_analysis (rtx f
, FILE *file
, int flags
)
401 #ifdef ELIMINABLE_REGS
403 static const struct {const int from
, to
; } eliminables
[] = ELIMINABLE_REGS
;
406 /* Record which registers will be eliminated. We use this in
409 CLEAR_HARD_REG_SET (elim_reg_set
);
411 #ifdef ELIMINABLE_REGS
412 for (i
= 0; i
< (int) ARRAY_SIZE (eliminables
); i
++)
413 SET_HARD_REG_BIT (elim_reg_set
, eliminables
[i
].from
);
415 SET_HARD_REG_BIT (elim_reg_set
, FRAME_POINTER_REGNUM
);
419 #ifdef CANNOT_CHANGE_MODE_CLASS
420 if (flags
& PROP_REG_INFO
)
421 bitmap_initialize (&subregs_of_mode
, 1);
425 flags
&= ~(PROP_LOG_LINKS
| PROP_AUTOINC
| PROP_ALLOW_CFG_CHANGES
);
427 /* The post-reload life analysis have (on a global basis) the same
428 registers live as was computed by reload itself. elimination
429 Otherwise offsets and such may be incorrect.
431 Reload will make some registers as live even though they do not
434 We don't want to create new auto-incs after reload, since they
435 are unlikely to be useful and can cause problems with shared
437 if (reload_completed
)
438 flags
&= ~(PROP_REG_INFO
| PROP_AUTOINC
);
440 /* We want alias analysis information for local dead store elimination. */
441 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
442 init_alias_analysis ();
444 /* Always remove no-op moves. Do this before other processing so
445 that we don't have to keep re-scanning them. */
446 delete_noop_moves (f
);
448 /* Some targets can emit simpler epilogues if they know that sp was
449 not ever modified during the function. After reload, of course,
450 we've already emitted the epilogue so there's no sense searching. */
451 if (! reload_completed
)
452 notice_stack_pointer_modification (f
);
454 /* Allocate and zero out data structures that will record the
455 data from lifetime analysis. */
456 allocate_reg_life_data ();
457 allocate_bb_life_data ();
459 /* Find the set of registers live on function exit. */
460 mark_regs_live_at_end (EXIT_BLOCK_PTR
->global_live_at_start
);
462 /* "Update" life info from zero. It'd be nice to begin the
463 relaxation with just the exit and noreturn blocks, but that set
464 is not immediately handy. */
466 if (flags
& PROP_REG_INFO
)
467 memset (regs_ever_live
, 0, sizeof (regs_ever_live
));
468 update_life_info (NULL
, UPDATE_LIFE_GLOBAL
, flags
);
471 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
472 end_alias_analysis ();
475 dump_flow_info (file
);
477 free_basic_block_vars (1);
479 /* Removing dead insns should've made jumptables really dead. */
480 delete_dead_jumptables ();
483 /* A subroutine of verify_wide_reg, called through for_each_rtx.
484 Search for REGNO. If found, return 2 if it is not wider than
488 verify_wide_reg_1 (rtx
*px
, void *pregno
)
491 unsigned int regno
= *(int *) pregno
;
493 if (GET_CODE (x
) == REG
&& REGNO (x
) == regno
)
495 if (GET_MODE_BITSIZE (GET_MODE (x
)) <= BITS_PER_WORD
)
502 /* A subroutine of verify_local_live_at_start. Search through insns
503 of BB looking for register REGNO. */
506 verify_wide_reg (int regno
, basic_block bb
)
508 rtx head
= bb
->head
, end
= bb
->end
;
514 int r
= for_each_rtx (&PATTERN (head
), verify_wide_reg_1
, ®no
);
522 head
= NEXT_INSN (head
);
527 fprintf (rtl_dump_file
, "Register %d died unexpectedly.\n", regno
);
528 dump_bb (bb
, rtl_dump_file
);
533 /* A subroutine of update_life_info. Verify that there are no untoward
534 changes in live_at_start during a local update. */
537 verify_local_live_at_start (regset new_live_at_start
, basic_block bb
)
539 if (reload_completed
)
541 /* After reload, there are no pseudos, nor subregs of multi-word
542 registers. The regsets should exactly match. */
543 if (! REG_SET_EQUAL_P (new_live_at_start
, bb
->global_live_at_start
))
547 fprintf (rtl_dump_file
,
548 "live_at_start mismatch in bb %d, aborting\nNew:\n",
550 debug_bitmap_file (rtl_dump_file
, new_live_at_start
);
551 fputs ("Old:\n", rtl_dump_file
);
552 dump_bb (bb
, rtl_dump_file
);
561 /* Find the set of changed registers. */
562 XOR_REG_SET (new_live_at_start
, bb
->global_live_at_start
);
564 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start
, 0, i
,
566 /* No registers should die. */
567 if (REGNO_REG_SET_P (bb
->global_live_at_start
, i
))
571 fprintf (rtl_dump_file
,
572 "Register %d died unexpectedly.\n", i
);
573 dump_bb (bb
, rtl_dump_file
);
578 /* Verify that the now-live register is wider than word_mode. */
579 verify_wide_reg (i
, bb
);
584 /* Updates life information starting with the basic blocks set in BLOCKS.
585 If BLOCKS is null, consider it to be the universal set.
587 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholing,
588 we are only expecting local modifications to basic blocks. If we find
589 extra registers live at the beginning of a block, then we either killed
590 useful data, or we have a broken split that wants data not provided.
591 If we find registers removed from live_at_start, that means we have
592 a broken peephole that is killing a register it shouldn't.
594 ??? This is not true in one situation -- when a pre-reload splitter
595 generates subregs of a multi-word pseudo, current life analysis will
596 lose the kill. So we _can_ have a pseudo go live. How irritating.
598 It is also not true when a peephole decides that it doesn't need one
599 or more of the inputs.
601 Including PROP_REG_INFO does not properly refresh regs_ever_live
602 unless the caller resets it to zero. */
605 update_life_info (sbitmap blocks
, enum update_life_extent extent
, int prop_flags
)
608 regset_head tmp_head
;
610 int stabilized_prop_flags
= prop_flags
;
613 tmp
= INITIALIZE_REG_SET (tmp_head
);
616 timevar_push ((extent
== UPDATE_LIFE_LOCAL
|| blocks
)
617 ? TV_LIFE_UPDATE
: TV_LIFE
);
619 /* Changes to the CFG are only allowed when
620 doing a global update for the entire CFG. */
621 if ((prop_flags
& PROP_ALLOW_CFG_CHANGES
)
622 && (extent
== UPDATE_LIFE_LOCAL
|| blocks
))
625 /* For a global update, we go through the relaxation process again. */
626 if (extent
!= UPDATE_LIFE_LOCAL
)
632 calculate_global_regs_live (blocks
, blocks
,
633 prop_flags
& (PROP_SCAN_DEAD_CODE
634 | PROP_SCAN_DEAD_STORES
635 | PROP_ALLOW_CFG_CHANGES
));
637 if ((prop_flags
& (PROP_KILL_DEAD_CODE
| PROP_ALLOW_CFG_CHANGES
))
638 != (PROP_KILL_DEAD_CODE
| PROP_ALLOW_CFG_CHANGES
))
641 /* Removing dead code may allow the CFG to be simplified which
642 in turn may allow for further dead code detection / removal. */
643 FOR_EACH_BB_REVERSE (bb
)
645 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
646 changed
|= propagate_block (bb
, tmp
, NULL
, NULL
,
647 prop_flags
& (PROP_SCAN_DEAD_CODE
648 | PROP_SCAN_DEAD_STORES
649 | PROP_KILL_DEAD_CODE
));
652 /* Don't pass PROP_SCAN_DEAD_CODE or PROP_KILL_DEAD_CODE to
653 subsequent propagate_block calls, since removing or acting as
654 removing dead code can affect global register liveness, which
655 is supposed to be finalized for this call after this loop. */
656 stabilized_prop_flags
657 &= ~(PROP_SCAN_DEAD_CODE
| PROP_SCAN_DEAD_STORES
658 | PROP_KILL_DEAD_CODE
);
663 /* We repeat regardless of what cleanup_cfg says. If there were
664 instructions deleted above, that might have been only a
665 partial improvement (see MAX_MEM_SET_LIST_LEN usage).
666 Further improvement may be possible. */
667 cleanup_cfg (CLEANUP_EXPENSIVE
);
669 /* Zap the life information from the last round. If we don't
670 do this, we can wind up with registers that no longer appear
671 in the code being marked live at entry, which twiggs bogus
672 warnings from regno_uninitialized. */
675 CLEAR_REG_SET (bb
->global_live_at_start
);
676 CLEAR_REG_SET (bb
->global_live_at_end
);
680 /* If asked, remove notes from the blocks we'll update. */
681 if (extent
== UPDATE_LIFE_GLOBAL_RM_NOTES
)
682 count_or_remove_death_notes (blocks
, 1);
685 /* Clear log links in case we are asked to (re)compute them. */
686 if (prop_flags
& PROP_LOG_LINKS
)
687 clear_log_links (blocks
);
691 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
693 bb
= BASIC_BLOCK (i
);
695 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
696 propagate_block (bb
, tmp
, NULL
, NULL
, stabilized_prop_flags
);
698 if (extent
== UPDATE_LIFE_LOCAL
)
699 verify_local_live_at_start (tmp
, bb
);
704 FOR_EACH_BB_REVERSE (bb
)
706 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
708 propagate_block (bb
, tmp
, NULL
, NULL
, stabilized_prop_flags
);
710 if (extent
== UPDATE_LIFE_LOCAL
)
711 verify_local_live_at_start (tmp
, bb
);
717 if (prop_flags
& PROP_REG_INFO
)
719 /* The only pseudos that are live at the beginning of the function
720 are those that were not set anywhere in the function. local-alloc
721 doesn't know how to handle these correctly, so mark them as not
722 local to any one basic block. */
723 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR
->global_live_at_end
,
724 FIRST_PSEUDO_REGISTER
, i
,
725 { REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
; });
727 /* We have a problem with any pseudoreg that lives across the setjmp.
728 ANSI says that if a user variable does not change in value between
729 the setjmp and the longjmp, then the longjmp preserves it. This
730 includes longjmp from a place where the pseudo appears dead.
731 (In principle, the value still exists if it is in scope.)
732 If the pseudo goes in a hard reg, some other value may occupy
733 that hard reg where this pseudo is dead, thus clobbering the pseudo.
734 Conclusion: such a pseudo must not go in a hard reg. */
735 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp
,
736 FIRST_PSEUDO_REGISTER
, i
,
738 if (regno_reg_rtx
[i
] != 0)
740 REG_LIVE_LENGTH (i
) = -1;
741 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
745 timevar_pop ((extent
== UPDATE_LIFE_LOCAL
|| blocks
)
746 ? TV_LIFE_UPDATE
: TV_LIFE
);
747 if (ndead
&& rtl_dump_file
)
748 fprintf (rtl_dump_file
, "deleted %i dead insns\n", ndead
);
752 /* Update life information in all blocks where BB_DIRTY is set. */
755 update_life_info_in_dirty_blocks (enum update_life_extent extent
, int prop_flags
)
757 sbitmap update_life_blocks
= sbitmap_alloc (last_basic_block
);
762 sbitmap_zero (update_life_blocks
);
765 if (extent
== UPDATE_LIFE_LOCAL
)
767 if (bb
->flags
& BB_DIRTY
)
769 SET_BIT (update_life_blocks
, bb
->index
);
775 /* ??? Bootstrap with -march=pentium4 fails to terminate
776 with only a partial life update. */
777 SET_BIT (update_life_blocks
, bb
->index
);
778 if (bb
->flags
& BB_DIRTY
)
784 retval
= update_life_info (update_life_blocks
, extent
, prop_flags
);
786 sbitmap_free (update_life_blocks
);
790 /* Free the variables allocated by find_basic_blocks.
792 KEEP_HEAD_END_P is nonzero if basic_block_info is not to be freed. */
795 free_basic_block_vars (int keep_head_end_p
)
797 if (! keep_head_end_p
)
799 if (basic_block_info
)
802 VARRAY_FREE (basic_block_info
);
805 last_basic_block
= 0;
807 ENTRY_BLOCK_PTR
->aux
= NULL
;
808 ENTRY_BLOCK_PTR
->global_live_at_end
= NULL
;
809 EXIT_BLOCK_PTR
->aux
= NULL
;
810 EXIT_BLOCK_PTR
->global_live_at_start
= NULL
;
814 /* Delete any insns that copy a register to itself. */
817 delete_noop_moves (rtx f ATTRIBUTE_UNUSED
)
825 for (insn
= bb
->head
; insn
!= NEXT_INSN (bb
->end
); insn
= next
)
827 next
= NEXT_INSN (insn
);
828 if (INSN_P (insn
) && noop_move_p (insn
))
832 /* If we're about to remove the first insn of a libcall
833 then move the libcall note to the next real insn and
834 update the retval note. */
835 if ((note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
836 && XEXP (note
, 0) != insn
)
838 rtx new_libcall_insn
= next_real_insn (insn
);
839 rtx retval_note
= find_reg_note (XEXP (note
, 0),
840 REG_RETVAL
, NULL_RTX
);
841 REG_NOTES (new_libcall_insn
)
842 = gen_rtx_INSN_LIST (REG_LIBCALL
, XEXP (note
, 0),
843 REG_NOTES (new_libcall_insn
));
844 XEXP (retval_note
, 0) = new_libcall_insn
;
847 delete_insn_and_edges (insn
);
852 if (nnoops
&& rtl_dump_file
)
853 fprintf (rtl_dump_file
, "deleted %i noop moves", nnoops
);
857 /* Delete any jump tables never referenced. We can't delete them at the
858 time of removing tablejump insn as they are referenced by the preceding
859 insns computing the destination, so we delay deleting and garbagecollect
860 them once life information is computed. */
862 delete_dead_jumptables (void)
865 for (insn
= get_insns (); insn
; insn
= next
)
867 next
= NEXT_INSN (insn
);
868 if (GET_CODE (insn
) == CODE_LABEL
869 && LABEL_NUSES (insn
) == LABEL_PRESERVE_P (insn
)
870 && GET_CODE (next
) == JUMP_INSN
871 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
872 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
875 fprintf (rtl_dump_file
, "Dead jumptable %i removed\n", INSN_UID (insn
));
876 delete_insn (NEXT_INSN (insn
));
878 next
= NEXT_INSN (next
);
883 /* Determine if the stack pointer is constant over the life of the function.
884 Only useful before prologues have been emitted. */
887 notice_stack_pointer_modification_1 (rtx x
, rtx pat ATTRIBUTE_UNUSED
,
888 void *data ATTRIBUTE_UNUSED
)
890 if (x
== stack_pointer_rtx
891 /* The stack pointer is only modified indirectly as the result
892 of a push until later in flow. See the comments in rtl.texi
893 regarding Embedded Side-Effects on Addresses. */
894 || (GET_CODE (x
) == MEM
895 && GET_RTX_CLASS (GET_CODE (XEXP (x
, 0))) == 'a'
896 && XEXP (XEXP (x
, 0), 0) == stack_pointer_rtx
))
897 current_function_sp_is_unchanging
= 0;
901 notice_stack_pointer_modification (rtx f
)
905 /* Assume that the stack pointer is unchanging if alloca hasn't
907 current_function_sp_is_unchanging
= !current_function_calls_alloca
;
908 if (! current_function_sp_is_unchanging
)
911 for (insn
= f
; insn
; insn
= NEXT_INSN (insn
))
915 /* Check if insn modifies the stack pointer. */
916 note_stores (PATTERN (insn
), notice_stack_pointer_modification_1
,
918 if (! current_function_sp_is_unchanging
)
924 /* Mark a register in SET. Hard registers in large modes get all
925 of their component registers set as well. */
928 mark_reg (rtx reg
, void *xset
)
930 regset set
= (regset
) xset
;
931 int regno
= REGNO (reg
);
933 if (GET_MODE (reg
) == BLKmode
)
936 SET_REGNO_REG_SET (set
, regno
);
937 if (regno
< FIRST_PSEUDO_REGISTER
)
939 int n
= HARD_REGNO_NREGS (regno
, GET_MODE (reg
));
941 SET_REGNO_REG_SET (set
, regno
+ n
);
945 /* Mark those regs which are needed at the end of the function as live
946 at the end of the last basic block. */
949 mark_regs_live_at_end (regset set
)
953 /* If exiting needs the right stack value, consider the stack pointer
954 live at the end of the function. */
955 if ((HAVE_epilogue
&& epilogue_completed
)
956 || ! EXIT_IGNORE_STACK
957 || (! FRAME_POINTER_REQUIRED
958 && ! current_function_calls_alloca
959 && flag_omit_frame_pointer
)
960 || current_function_sp_is_unchanging
)
962 SET_REGNO_REG_SET (set
, STACK_POINTER_REGNUM
);
965 /* Mark the frame pointer if needed at the end of the function. If
966 we end up eliminating it, it will be removed from the live list
967 of each basic block by reload. */
969 if (! reload_completed
|| frame_pointer_needed
)
971 SET_REGNO_REG_SET (set
, FRAME_POINTER_REGNUM
);
972 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
973 /* If they are different, also mark the hard frame pointer as live. */
974 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM
))
975 SET_REGNO_REG_SET (set
, HARD_FRAME_POINTER_REGNUM
);
979 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
980 /* Many architectures have a GP register even without flag_pic.
981 Assume the pic register is not in use, or will be handled by
982 other means, if it is not fixed. */
983 if ((unsigned) PIC_OFFSET_TABLE_REGNUM
!= INVALID_REGNUM
984 && fixed_regs
[PIC_OFFSET_TABLE_REGNUM
])
985 SET_REGNO_REG_SET (set
, PIC_OFFSET_TABLE_REGNUM
);
988 /* Mark all global registers, and all registers used by the epilogue
989 as being live at the end of the function since they may be
990 referenced by our caller. */
991 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
992 if (global_regs
[i
] || EPILOGUE_USES (i
))
993 SET_REGNO_REG_SET (set
, i
);
995 if (HAVE_epilogue
&& epilogue_completed
)
997 /* Mark all call-saved registers that we actually used. */
998 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
999 if (regs_ever_live
[i
] && ! LOCAL_REGNO (i
)
1000 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
))
1001 SET_REGNO_REG_SET (set
, i
);
1004 #ifdef EH_RETURN_DATA_REGNO
1005 /* Mark the registers that will contain data for the handler. */
1006 if (reload_completed
&& current_function_calls_eh_return
)
1009 unsigned regno
= EH_RETURN_DATA_REGNO(i
);
1010 if (regno
== INVALID_REGNUM
)
1012 SET_REGNO_REG_SET (set
, regno
);
1015 #ifdef EH_RETURN_STACKADJ_RTX
1016 if ((! HAVE_epilogue
|| ! epilogue_completed
)
1017 && current_function_calls_eh_return
)
1019 rtx tmp
= EH_RETURN_STACKADJ_RTX
;
1020 if (tmp
&& REG_P (tmp
))
1021 mark_reg (tmp
, set
);
1024 #ifdef EH_RETURN_HANDLER_RTX
1025 if ((! HAVE_epilogue
|| ! epilogue_completed
)
1026 && current_function_calls_eh_return
)
1028 rtx tmp
= EH_RETURN_HANDLER_RTX
;
1029 if (tmp
&& REG_P (tmp
))
1030 mark_reg (tmp
, set
);
1034 /* Mark function return value. */
1035 diddle_return_value (mark_reg
, set
);
1038 /* Propagate global life info around the graph of basic blocks. Begin
1039 considering blocks with their corresponding bit set in BLOCKS_IN.
1040 If BLOCKS_IN is null, consider it the universal set.
1042 BLOCKS_OUT is set for every block that was changed. */
1045 calculate_global_regs_live (sbitmap blocks_in
, sbitmap blocks_out
, int flags
)
1047 basic_block
*queue
, *qhead
, *qtail
, *qend
, bb
;
1048 regset tmp
, new_live_at_end
, invalidated_by_call
;
1049 regset_head tmp_head
, invalidated_by_call_head
;
1050 regset_head new_live_at_end_head
;
1053 /* Some passes used to forget clear aux field of basic block causing
1054 sick behavior here. */
1055 #ifdef ENABLE_CHECKING
1056 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
1061 tmp
= INITIALIZE_REG_SET (tmp_head
);
1062 new_live_at_end
= INITIALIZE_REG_SET (new_live_at_end_head
);
1063 invalidated_by_call
= INITIALIZE_REG_SET (invalidated_by_call_head
);
1065 /* Inconveniently, this is only readily available in hard reg set form. */
1066 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; ++i
)
1067 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
))
1068 SET_REGNO_REG_SET (invalidated_by_call
, i
);
1070 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1071 because the `head == tail' style test for an empty queue doesn't
1072 work with a full queue. */
1073 queue
= xmalloc ((n_basic_blocks
+ 2) * sizeof (*queue
));
1075 qhead
= qend
= queue
+ n_basic_blocks
+ 2;
1077 /* Queue the blocks set in the initial mask. Do this in reverse block
1078 number order so that we are more likely for the first round to do
1079 useful work. We use AUX non-null to flag that the block is queued. */
1083 if (TEST_BIT (blocks_in
, bb
->index
))
1098 /* We clean aux when we remove the initially-enqueued bbs, but we
1099 don't enqueue ENTRY and EXIT initially, so clean them upfront and
1101 ENTRY_BLOCK_PTR
->aux
= EXIT_BLOCK_PTR
->aux
= NULL
;
1104 sbitmap_zero (blocks_out
);
1106 /* We work through the queue until there are no more blocks. What
1107 is live at the end of this block is precisely the union of what
1108 is live at the beginning of all its successors. So, we set its
1109 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1110 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1111 this block by walking through the instructions in this block in
1112 reverse order and updating as we go. If that changed
1113 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1114 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1116 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1117 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1118 must either be live at the end of the block, or used within the
1119 block. In the latter case, it will certainly never disappear
1120 from GLOBAL_LIVE_AT_START. In the former case, the register
1121 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1122 for one of the successor blocks. By induction, that cannot
1124 while (qhead
!= qtail
)
1126 int rescan
, changed
;
1135 /* Begin by propagating live_at_start from the successor blocks. */
1136 CLEAR_REG_SET (new_live_at_end
);
1139 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
1141 basic_block sb
= e
->dest
;
1143 /* Call-clobbered registers die across exception and
1145 /* ??? Abnormal call edges ignored for the moment, as this gets
1146 confused by sibling call edges, which crashes reg-stack. */
1147 if (e
->flags
& EDGE_EH
)
1149 bitmap_operation (tmp
, sb
->global_live_at_start
,
1150 invalidated_by_call
, BITMAP_AND_COMPL
);
1151 IOR_REG_SET (new_live_at_end
, tmp
);
1154 IOR_REG_SET (new_live_at_end
, sb
->global_live_at_start
);
1156 /* If a target saves one register in another (instead of on
1157 the stack) the save register will need to be live for EH. */
1158 if (e
->flags
& EDGE_EH
)
1159 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1161 SET_REGNO_REG_SET (new_live_at_end
, i
);
1165 /* This might be a noreturn function that throws. And
1166 even if it isn't, getting the unwind info right helps
1168 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1170 SET_REGNO_REG_SET (new_live_at_end
, i
);
1173 /* The all-important stack pointer must always be live. */
1174 SET_REGNO_REG_SET (new_live_at_end
, STACK_POINTER_REGNUM
);
1176 /* Before reload, there are a few registers that must be forced
1177 live everywhere -- which might not already be the case for
1178 blocks within infinite loops. */
1179 if (! reload_completed
)
1181 /* Any reference to any pseudo before reload is a potential
1182 reference of the frame pointer. */
1183 SET_REGNO_REG_SET (new_live_at_end
, FRAME_POINTER_REGNUM
);
1185 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1186 /* Pseudos with argument area equivalences may require
1187 reloading via the argument pointer. */
1188 if (fixed_regs
[ARG_POINTER_REGNUM
])
1189 SET_REGNO_REG_SET (new_live_at_end
, ARG_POINTER_REGNUM
);
1192 /* Any constant, or pseudo with constant equivalences, may
1193 require reloading from memory using the pic register. */
1194 if ((unsigned) PIC_OFFSET_TABLE_REGNUM
!= INVALID_REGNUM
1195 && fixed_regs
[PIC_OFFSET_TABLE_REGNUM
])
1196 SET_REGNO_REG_SET (new_live_at_end
, PIC_OFFSET_TABLE_REGNUM
);
1199 if (bb
== ENTRY_BLOCK_PTR
)
1201 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1205 /* On our first pass through this block, we'll go ahead and continue.
1206 Recognize first pass by local_set NULL. On subsequent passes, we
1207 get to skip out early if live_at_end wouldn't have changed. */
1209 if (bb
->local_set
== NULL
)
1211 bb
->local_set
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1212 bb
->cond_local_set
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1217 /* If any bits were removed from live_at_end, we'll have to
1218 rescan the block. This wouldn't be necessary if we had
1219 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1220 local_live is really dependent on live_at_end. */
1221 CLEAR_REG_SET (tmp
);
1222 rescan
= bitmap_operation (tmp
, bb
->global_live_at_end
,
1223 new_live_at_end
, BITMAP_AND_COMPL
);
1227 /* If any of the registers in the new live_at_end set are
1228 conditionally set in this basic block, we must rescan.
1229 This is because conditional lifetimes at the end of the
1230 block do not just take the live_at_end set into account,
1231 but also the liveness at the start of each successor
1232 block. We can miss changes in those sets if we only
1233 compare the new live_at_end against the previous one. */
1234 CLEAR_REG_SET (tmp
);
1235 rescan
= bitmap_operation (tmp
, new_live_at_end
,
1236 bb
->cond_local_set
, BITMAP_AND
);
1241 /* Find the set of changed bits. Take this opportunity
1242 to notice that this set is empty and early out. */
1243 CLEAR_REG_SET (tmp
);
1244 changed
= bitmap_operation (tmp
, bb
->global_live_at_end
,
1245 new_live_at_end
, BITMAP_XOR
);
1249 /* If any of the changed bits overlap with local_set,
1250 we'll have to rescan the block. Detect overlap by
1251 the AND with ~local_set turning off bits. */
1252 rescan
= bitmap_operation (tmp
, tmp
, bb
->local_set
,
1257 /* Let our caller know that BB changed enough to require its
1258 death notes updated. */
1260 SET_BIT (blocks_out
, bb
->index
);
1264 /* Add to live_at_start the set of all registers in
1265 new_live_at_end that aren't in the old live_at_end. */
1267 bitmap_operation (tmp
, new_live_at_end
, bb
->global_live_at_end
,
1269 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1271 changed
= bitmap_operation (bb
->global_live_at_start
,
1272 bb
->global_live_at_start
,
1279 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1281 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1282 into live_at_start. */
1283 propagate_block (bb
, new_live_at_end
, bb
->local_set
,
1284 bb
->cond_local_set
, flags
);
1286 /* If live_at start didn't change, no need to go farther. */
1287 if (REG_SET_EQUAL_P (bb
->global_live_at_start
, new_live_at_end
))
1290 COPY_REG_SET (bb
->global_live_at_start
, new_live_at_end
);
1293 /* Queue all predecessors of BB so that we may re-examine
1294 their live_at_end. */
1295 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
1297 basic_block pb
= e
->src
;
1298 if (pb
->aux
== NULL
)
1309 FREE_REG_SET (new_live_at_end
);
1310 FREE_REG_SET (invalidated_by_call
);
1314 EXECUTE_IF_SET_IN_SBITMAP (blocks_out
, 0, i
,
1316 basic_block bb
= BASIC_BLOCK (i
);
1317 FREE_REG_SET (bb
->local_set
);
1318 FREE_REG_SET (bb
->cond_local_set
);
1325 FREE_REG_SET (bb
->local_set
);
1326 FREE_REG_SET (bb
->cond_local_set
);
1334 /* This structure is used to pass parameters to and from the
1335 the function find_regno_partial(). It is used to pass in the
1336 register number we are looking, as well as to return any rtx
1340 unsigned regno_to_find
;
1342 } find_regno_partial_param
;
1345 /* Find the rtx for the reg numbers specified in 'data' if it is
1346 part of an expression which only uses part of the register. Return
1347 it in the structure passed in. */
1349 find_regno_partial (rtx
*ptr
, void *data
)
1351 find_regno_partial_param
*param
= (find_regno_partial_param
*)data
;
1352 unsigned reg
= param
->regno_to_find
;
1353 param
->retval
= NULL_RTX
;
1355 if (*ptr
== NULL_RTX
)
1358 switch (GET_CODE (*ptr
))
1362 case STRICT_LOW_PART
:
1363 if (GET_CODE (XEXP (*ptr
, 0)) == REG
&& REGNO (XEXP (*ptr
, 0)) == reg
)
1365 param
->retval
= XEXP (*ptr
, 0);
1371 if (GET_CODE (SUBREG_REG (*ptr
)) == REG
1372 && REGNO (SUBREG_REG (*ptr
)) == reg
)
1374 param
->retval
= SUBREG_REG (*ptr
);
1386 /* Process all immediate successors of the entry block looking for pseudo
1387 registers which are live on entry. Find all of those whose first
1388 instance is a partial register reference of some kind, and initialize
1389 them to 0 after the entry block. This will prevent bit sets within
1390 registers whose value is unknown, and may contain some kind of sticky
1391 bits we don't want. */
1394 initialize_uninitialized_subregs (void)
1398 int reg
, did_something
= 0;
1399 find_regno_partial_param param
;
1401 for (e
= ENTRY_BLOCK_PTR
->succ
; e
; e
= e
->succ_next
)
1403 basic_block bb
= e
->dest
;
1404 regset map
= bb
->global_live_at_start
;
1405 EXECUTE_IF_SET_IN_REG_SET (map
,
1406 FIRST_PSEUDO_REGISTER
, reg
,
1408 int uid
= REGNO_FIRST_UID (reg
);
1411 /* Find an insn which mentions the register we are looking for.
1412 Its preferable to have an instance of the register's rtl since
1413 there may be various flags set which we need to duplicate.
1414 If we can't find it, its probably an automatic whose initial
1415 value doesn't matter, or hopefully something we don't care about. */
1416 for (i
= get_insns (); i
&& INSN_UID (i
) != uid
; i
= NEXT_INSN (i
))
1420 /* Found the insn, now get the REG rtx, if we can. */
1421 param
.regno_to_find
= reg
;
1422 for_each_rtx (&i
, find_regno_partial
, ¶m
);
1423 if (param
.retval
!= NULL_RTX
)
1426 emit_move_insn (param
.retval
,
1427 CONST0_RTX (GET_MODE (param
.retval
)));
1428 insn
= get_insns ();
1430 insert_insn_on_edge (insn
, e
);
1438 commit_edge_insertions ();
1439 return did_something
;
1443 /* Subroutines of life analysis. */
1445 /* Allocate the permanent data structures that represent the results
1446 of life analysis. Not static since used also for stupid life analysis. */
1449 allocate_bb_life_data (void)
1453 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
1455 bb
->global_live_at_start
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1456 bb
->global_live_at_end
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1459 regs_live_at_setjmp
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1463 allocate_reg_life_data (void)
1467 max_regno
= max_reg_num ();
1469 /* Recalculate the register space, in case it has grown. Old style
1470 vector oriented regsets would set regset_{size,bytes} here also. */
1471 allocate_reg_info (max_regno
, FALSE
, FALSE
);
1473 /* Reset all the data we'll collect in propagate_block and its
1475 for (i
= 0; i
< max_regno
; i
++)
1479 REG_N_DEATHS (i
) = 0;
1480 REG_N_CALLS_CROSSED (i
) = 0;
1481 REG_LIVE_LENGTH (i
) = 0;
1483 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
1487 /* Delete dead instructions for propagate_block. */
1490 propagate_block_delete_insn (rtx insn
)
1492 rtx inote
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
);
1494 /* If the insn referred to a label, and that label was attached to
1495 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1496 pretty much mandatory to delete it, because the ADDR_VEC may be
1497 referencing labels that no longer exist.
1499 INSN may reference a deleted label, particularly when a jump
1500 table has been optimized into a direct jump. There's no
1501 real good way to fix up the reference to the deleted label
1502 when the label is deleted, so we just allow it here. */
1504 if (inote
&& GET_CODE (inote
) == CODE_LABEL
)
1506 rtx label
= XEXP (inote
, 0);
1509 /* The label may be forced if it has been put in the constant
1510 pool. If that is the only use we must discard the table
1511 jump following it, but not the label itself. */
1512 if (LABEL_NUSES (label
) == 1 + LABEL_PRESERVE_P (label
)
1513 && (next
= next_nonnote_insn (label
)) != NULL
1514 && GET_CODE (next
) == JUMP_INSN
1515 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
1516 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
1518 rtx pat
= PATTERN (next
);
1519 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
1520 int len
= XVECLEN (pat
, diff_vec_p
);
1523 for (i
= 0; i
< len
; i
++)
1524 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))--;
1526 delete_insn_and_edges (next
);
1531 delete_insn_and_edges (insn
);
1535 /* Delete dead libcalls for propagate_block. Return the insn
1536 before the libcall. */
1539 propagate_block_delete_libcall (rtx insn
, rtx note
)
1541 rtx first
= XEXP (note
, 0);
1542 rtx before
= PREV_INSN (first
);
1544 delete_insn_chain_and_edges (first
, insn
);
1549 /* Update the life-status of regs for one insn. Return the previous insn. */
1552 propagate_one_insn (struct propagate_block_info
*pbi
, rtx insn
)
1554 rtx prev
= PREV_INSN (insn
);
1555 int flags
= pbi
->flags
;
1556 int insn_is_dead
= 0;
1557 int libcall_is_dead
= 0;
1561 if (! INSN_P (insn
))
1564 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
1565 if (flags
& PROP_SCAN_DEAD_CODE
)
1567 insn_is_dead
= insn_dead_p (pbi
, PATTERN (insn
), 0, REG_NOTES (insn
));
1568 libcall_is_dead
= (insn_is_dead
&& note
!= 0
1569 && libcall_dead_p (pbi
, note
, insn
));
1572 /* If an instruction consists of just dead store(s) on final pass,
1574 if ((flags
& PROP_KILL_DEAD_CODE
) && insn_is_dead
)
1576 /* If we're trying to delete a prologue or epilogue instruction
1577 that isn't flagged as possibly being dead, something is wrong.
1578 But if we are keeping the stack pointer depressed, we might well
1579 be deleting insns that are used to compute the amount to update
1580 it by, so they are fine. */
1581 if (reload_completed
1582 && !(TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1583 && (TYPE_RETURNS_STACK_DEPRESSED
1584 (TREE_TYPE (current_function_decl
))))
1585 && (((HAVE_epilogue
|| HAVE_prologue
)
1586 && prologue_epilogue_contains (insn
))
1587 || (HAVE_sibcall_epilogue
1588 && sibcall_epilogue_contains (insn
)))
1589 && find_reg_note (insn
, REG_MAYBE_DEAD
, NULL_RTX
) == 0)
1590 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn
);
1592 /* Record sets. Do this even for dead instructions, since they
1593 would have killed the values if they hadn't been deleted. */
1594 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1596 /* CC0 is now known to be dead. Either this insn used it,
1597 in which case it doesn't anymore, or clobbered it,
1598 so the next insn can't use it. */
1601 if (libcall_is_dead
)
1602 prev
= propagate_block_delete_libcall ( insn
, note
);
1606 /* If INSN contains a RETVAL note and is dead, but the libcall
1607 as a whole is not dead, then we want to remove INSN, but
1608 not the whole libcall sequence.
1610 However, we need to also remove the dangling REG_LIBCALL
1611 note so that we do not have mis-matched LIBCALL/RETVAL
1612 notes. In theory we could find a new location for the
1613 REG_RETVAL note, but it hardly seems worth the effort.
1615 NOTE at this point will be the RETVAL note if it exists. */
1621 = find_reg_note (XEXP (note
, 0), REG_LIBCALL
, NULL_RTX
);
1622 remove_note (XEXP (note
, 0), libcall_note
);
1625 /* Similarly if INSN contains a LIBCALL note, remove the
1626 dangling REG_RETVAL note. */
1627 note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
);
1633 = find_reg_note (XEXP (note
, 0), REG_RETVAL
, NULL_RTX
);
1634 remove_note (XEXP (note
, 0), retval_note
);
1637 /* Now delete INSN. */
1638 propagate_block_delete_insn (insn
);
1644 /* See if this is an increment or decrement that can be merged into
1645 a following memory address. */
1648 rtx x
= single_set (insn
);
1650 /* Does this instruction increment or decrement a register? */
1651 if ((flags
& PROP_AUTOINC
)
1653 && GET_CODE (SET_DEST (x
)) == REG
1654 && (GET_CODE (SET_SRC (x
)) == PLUS
1655 || GET_CODE (SET_SRC (x
)) == MINUS
)
1656 && XEXP (SET_SRC (x
), 0) == SET_DEST (x
)
1657 && GET_CODE (XEXP (SET_SRC (x
), 1)) == CONST_INT
1658 /* Ok, look for a following memory ref we can combine with.
1659 If one is found, change the memory ref to a PRE_INC
1660 or PRE_DEC, cancel this insn, and return 1.
1661 Return 0 if nothing has been done. */
1662 && try_pre_increment_1 (pbi
, insn
))
1665 #endif /* AUTO_INC_DEC */
1667 CLEAR_REG_SET (pbi
->new_set
);
1669 /* If this is not the final pass, and this insn is copying the value of
1670 a library call and it's dead, don't scan the insns that perform the
1671 library call, so that the call's arguments are not marked live. */
1672 if (libcall_is_dead
)
1674 /* Record the death of the dest reg. */
1675 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1677 insn
= XEXP (note
, 0);
1678 return PREV_INSN (insn
);
1680 else if (GET_CODE (PATTERN (insn
)) == SET
1681 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
1682 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
1683 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
1684 && GET_CODE (XEXP (SET_SRC (PATTERN (insn
)), 1)) == CONST_INT
)
1685 /* We have an insn to pop a constant amount off the stack.
1686 (Such insns use PLUS regardless of the direction of the stack,
1687 and any insn to adjust the stack by a constant is always a pop.)
1688 These insns, if not dead stores, have no effect on life, though
1689 they do have an effect on the memory stores we are tracking. */
1690 invalidate_mems_from_set (pbi
, stack_pointer_rtx
);
1694 /* Any regs live at the time of a call instruction must not go
1695 in a register clobbered by calls. Find all regs now live and
1696 record this for them. */
1698 if (GET_CODE (insn
) == CALL_INSN
&& (flags
& PROP_REG_INFO
))
1699 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
,
1700 { REG_N_CALLS_CROSSED (i
)++; });
1702 /* Record sets. Do this even for dead instructions, since they
1703 would have killed the values if they hadn't been deleted. */
1704 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1706 if (GET_CODE (insn
) == CALL_INSN
)
1714 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1715 cond
= COND_EXEC_TEST (PATTERN (insn
));
1717 /* Non-constant calls clobber memory, constant calls do not
1718 clobber memory, though they may clobber outgoing arguments
1720 if (! CONST_OR_PURE_CALL_P (insn
))
1722 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1723 pbi
->mem_set_list_len
= 0;
1726 invalidate_mems_from_set (pbi
, stack_pointer_rtx
);
1728 /* There may be extra registers to be clobbered. */
1729 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
1731 note
= XEXP (note
, 1))
1732 if (GET_CODE (XEXP (note
, 0)) == CLOBBER
)
1733 mark_set_1 (pbi
, CLOBBER
, XEXP (XEXP (note
, 0), 0),
1734 cond
, insn
, pbi
->flags
);
1736 /* Calls change all call-used and global registers; sibcalls do not
1737 clobber anything that must be preserved at end-of-function,
1738 except for return values. */
1740 sibcall_p
= SIBLING_CALL_P (insn
);
1741 live_at_end
= EXIT_BLOCK_PTR
->global_live_at_start
;
1742 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1743 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
)
1745 && REGNO_REG_SET_P (live_at_end
, i
)
1746 && ! refers_to_regno_p (i
, i
+1,
1747 current_function_return_rtx
,
1750 /* We do not want REG_UNUSED notes for these registers. */
1751 mark_set_1 (pbi
, CLOBBER
, regno_reg_rtx
[i
], cond
, insn
,
1752 pbi
->flags
& ~(PROP_DEATH_NOTES
| PROP_REG_INFO
));
1756 /* If an insn doesn't use CC0, it becomes dead since we assume
1757 that every insn clobbers it. So show it dead here;
1758 mark_used_regs will set it live if it is referenced. */
1763 mark_used_regs (pbi
, PATTERN (insn
), NULL_RTX
, insn
);
1764 if ((flags
& PROP_EQUAL_NOTES
)
1765 && ((note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
))
1766 || (note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
))))
1767 mark_used_regs (pbi
, XEXP (note
, 0), NULL_RTX
, insn
);
1769 /* Sometimes we may have inserted something before INSN (such as a move)
1770 when we make an auto-inc. So ensure we will scan those insns. */
1772 prev
= PREV_INSN (insn
);
1775 if (! insn_is_dead
&& GET_CODE (insn
) == CALL_INSN
)
1781 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1782 cond
= COND_EXEC_TEST (PATTERN (insn
));
1784 /* Calls use their arguments, and may clobber memory which
1785 address involves some register. */
1786 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
1788 note
= XEXP (note
, 1))
1789 /* We find USE or CLOBBER entities in a FUNCTION_USAGE list: both
1790 of which mark_used_regs knows how to handle. */
1791 mark_used_regs (pbi
, XEXP (XEXP (note
, 0), 0), cond
, insn
);
1793 /* The stack ptr is used (honorarily) by a CALL insn. */
1794 SET_REGNO_REG_SET (pbi
->reg_live
, STACK_POINTER_REGNUM
);
1796 /* Calls may also reference any of the global registers,
1797 so they are made live. */
1798 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1800 mark_used_reg (pbi
, regno_reg_rtx
[i
], cond
, insn
);
1804 /* On final pass, update counts of how many insns in which each reg
1806 if (flags
& PROP_REG_INFO
)
1807 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
,
1808 { REG_LIVE_LENGTH (i
)++; });
1813 /* Initialize a propagate_block_info struct for public consumption.
1814 Note that the structure itself is opaque to this file, but that
1815 the user can use the regsets provided here. */
1817 struct propagate_block_info
*
1818 init_propagate_block_info (basic_block bb
, regset live
, regset local_set
,
1819 regset cond_local_set
, int flags
)
1821 struct propagate_block_info
*pbi
= xmalloc (sizeof (*pbi
));
1824 pbi
->reg_live
= live
;
1825 pbi
->mem_set_list
= NULL_RTX
;
1826 pbi
->mem_set_list_len
= 0;
1827 pbi
->local_set
= local_set
;
1828 pbi
->cond_local_set
= cond_local_set
;
1832 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
1833 pbi
->reg_next_use
= xcalloc (max_reg_num (), sizeof (rtx
));
1835 pbi
->reg_next_use
= NULL
;
1837 pbi
->new_set
= BITMAP_XMALLOC ();
1839 #ifdef HAVE_conditional_execution
1840 pbi
->reg_cond_dead
= splay_tree_new (splay_tree_compare_ints
, NULL
,
1841 free_reg_cond_life_info
);
1842 pbi
->reg_cond_reg
= BITMAP_XMALLOC ();
1844 /* If this block ends in a conditional branch, for each register
1845 live from one side of the branch and not the other, record the
1846 register as conditionally dead. */
1847 if (GET_CODE (bb
->end
) == JUMP_INSN
1848 && any_condjump_p (bb
->end
))
1850 regset_head diff_head
;
1851 regset diff
= INITIALIZE_REG_SET (diff_head
);
1852 basic_block bb_true
, bb_false
;
1855 /* Identify the successor blocks. */
1856 bb_true
= bb
->succ
->dest
;
1857 if (bb
->succ
->succ_next
!= NULL
)
1859 bb_false
= bb
->succ
->succ_next
->dest
;
1861 if (bb
->succ
->flags
& EDGE_FALLTHRU
)
1863 basic_block t
= bb_false
;
1867 else if (! (bb
->succ
->succ_next
->flags
& EDGE_FALLTHRU
))
1872 /* This can happen with a conditional jump to the next insn. */
1873 if (JUMP_LABEL (bb
->end
) != bb_true
->head
)
1876 /* Simplest way to do nothing. */
1880 /* Compute which register lead different lives in the successors. */
1881 if (bitmap_operation (diff
, bb_true
->global_live_at_start
,
1882 bb_false
->global_live_at_start
, BITMAP_XOR
))
1884 /* Extract the condition from the branch. */
1885 rtx set_src
= SET_SRC (pc_set (bb
->end
));
1886 rtx cond_true
= XEXP (set_src
, 0);
1887 rtx reg
= XEXP (cond_true
, 0);
1889 if (GET_CODE (reg
) == SUBREG
)
1890 reg
= SUBREG_REG (reg
);
1892 /* We can only track conditional lifetimes if the condition is
1893 in the form of a comparison of a register against zero.
1894 If the condition is more complex than that, then it is safe
1895 not to record any information. */
1896 if (GET_CODE (reg
) == REG
1897 && XEXP (cond_true
, 1) == const0_rtx
)
1900 = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true
)),
1901 GET_MODE (cond_true
), XEXP (cond_true
, 0),
1902 XEXP (cond_true
, 1));
1903 if (GET_CODE (XEXP (set_src
, 1)) == PC
)
1906 cond_false
= cond_true
;
1910 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (reg
));
1912 /* For each such register, mark it conditionally dead. */
1913 EXECUTE_IF_SET_IN_REG_SET
1916 struct reg_cond_life_info
*rcli
;
1919 rcli
= xmalloc (sizeof (*rcli
));
1921 if (REGNO_REG_SET_P (bb_true
->global_live_at_start
, i
))
1925 rcli
->condition
= cond
;
1926 rcli
->stores
= const0_rtx
;
1927 rcli
->orig_condition
= cond
;
1929 splay_tree_insert (pbi
->reg_cond_dead
, i
,
1930 (splay_tree_value
) rcli
);
1935 FREE_REG_SET (diff
);
1939 /* If this block has no successors, any stores to the frame that aren't
1940 used later in the block are dead. So make a pass over the block
1941 recording any such that are made and show them dead at the end. We do
1942 a very conservative and simple job here. */
1944 && ! (TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1945 && (TYPE_RETURNS_STACK_DEPRESSED
1946 (TREE_TYPE (current_function_decl
))))
1947 && (flags
& PROP_SCAN_DEAD_STORES
)
1948 && (bb
->succ
== NULL
1949 || (bb
->succ
->succ_next
== NULL
1950 && bb
->succ
->dest
== EXIT_BLOCK_PTR
1951 && ! current_function_calls_eh_return
)))
1954 for (insn
= bb
->end
; insn
!= bb
->head
; insn
= PREV_INSN (insn
))
1955 if (GET_CODE (insn
) == INSN
1956 && (set
= single_set (insn
))
1957 && GET_CODE (SET_DEST (set
)) == MEM
)
1959 rtx mem
= SET_DEST (set
);
1960 rtx canon_mem
= canon_rtx (mem
);
1962 if (XEXP (canon_mem
, 0) == frame_pointer_rtx
1963 || (GET_CODE (XEXP (canon_mem
, 0)) == PLUS
1964 && XEXP (XEXP (canon_mem
, 0), 0) == frame_pointer_rtx
1965 && GET_CODE (XEXP (XEXP (canon_mem
, 0), 1)) == CONST_INT
))
1966 add_to_mem_set_list (pbi
, canon_mem
);
1973 /* Release a propagate_block_info struct. */
1976 free_propagate_block_info (struct propagate_block_info
*pbi
)
1978 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1980 BITMAP_XFREE (pbi
->new_set
);
1982 #ifdef HAVE_conditional_execution
1983 splay_tree_delete (pbi
->reg_cond_dead
);
1984 BITMAP_XFREE (pbi
->reg_cond_reg
);
1987 if (pbi
->reg_next_use
)
1988 free (pbi
->reg_next_use
);
1993 /* Compute the registers live at the beginning of a basic block BB from
1994 those live at the end.
1996 When called, REG_LIVE contains those live at the end. On return, it
1997 contains those live at the beginning.
1999 LOCAL_SET, if non-null, will be set with all registers killed
2000 unconditionally by this basic block.
2001 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
2002 killed conditionally by this basic block. If there is any unconditional
2003 set of a register, then the corresponding bit will be set in LOCAL_SET
2004 and cleared in COND_LOCAL_SET.
2005 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
2006 case, the resulting set will be equal to the union of the two sets that
2007 would otherwise be computed.
2009 Return nonzero if an INSN is deleted (i.e. by dead code removal). */
2012 propagate_block (basic_block bb
, regset live
, regset local_set
,
2013 regset cond_local_set
, int flags
)
2015 struct propagate_block_info
*pbi
;
2019 pbi
= init_propagate_block_info (bb
, live
, local_set
, cond_local_set
, flags
);
2021 if (flags
& PROP_REG_INFO
)
2025 /* Process the regs live at the end of the block.
2026 Mark them as not local to any one basic block. */
2027 EXECUTE_IF_SET_IN_REG_SET (live
, 0, i
,
2028 { REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
; });
2031 /* Scan the block an insn at a time from end to beginning. */
2034 for (insn
= bb
->end
;; insn
= prev
)
2036 /* If this is a call to `setjmp' et al, warn if any
2037 non-volatile datum is live. */
2038 if ((flags
& PROP_REG_INFO
)
2039 && GET_CODE (insn
) == CALL_INSN
2040 && find_reg_note (insn
, REG_SETJMP
, NULL
))
2041 IOR_REG_SET (regs_live_at_setjmp
, pbi
->reg_live
);
2043 prev
= propagate_one_insn (pbi
, insn
);
2045 changed
|= insn
!= get_insns ();
2047 changed
|= NEXT_INSN (prev
) != insn
;
2049 if (insn
== bb
->head
)
2053 free_propagate_block_info (pbi
);
2058 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2059 (SET expressions whose destinations are registers dead after the insn).
2060 NEEDED is the regset that says which regs are alive after the insn.
2062 Unless CALL_OK is nonzero, an insn is needed if it contains a CALL.
2064 If X is the entire body of an insn, NOTES contains the reg notes
2065 pertaining to the insn. */
2068 insn_dead_p (struct propagate_block_info
*pbi
, rtx x
, int call_ok
,
2069 rtx notes ATTRIBUTE_UNUSED
)
2071 enum rtx_code code
= GET_CODE (x
);
2073 /* Don't eliminate insns that may trap. */
2074 if (flag_non_call_exceptions
&& may_trap_p (x
))
2078 /* As flow is invoked after combine, we must take existing AUTO_INC
2079 expressions into account. */
2080 for (; notes
; notes
= XEXP (notes
, 1))
2082 if (REG_NOTE_KIND (notes
) == REG_INC
)
2084 int regno
= REGNO (XEXP (notes
, 0));
2086 /* Don't delete insns to set global regs. */
2087 if ((regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2088 || REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2094 /* If setting something that's a reg or part of one,
2095 see if that register's altered value will be live. */
2099 rtx r
= SET_DEST (x
);
2102 if (GET_CODE (r
) == CC0
)
2103 return ! pbi
->cc0_live
;
2106 /* A SET that is a subroutine call cannot be dead. */
2107 if (GET_CODE (SET_SRC (x
)) == CALL
)
2113 /* Don't eliminate loads from volatile memory or volatile asms. */
2114 else if (volatile_refs_p (SET_SRC (x
)))
2117 if (GET_CODE (r
) == MEM
)
2121 if (MEM_VOLATILE_P (r
) || GET_MODE (r
) == BLKmode
)
2124 canon_r
= canon_rtx (r
);
2126 /* Walk the set of memory locations we are currently tracking
2127 and see if one is an identical match to this memory location.
2128 If so, this memory write is dead (remember, we're walking
2129 backwards from the end of the block to the start). Since
2130 rtx_equal_p does not check the alias set or flags, we also
2131 must have the potential for them to conflict (anti_dependence). */
2132 for (temp
= pbi
->mem_set_list
; temp
!= 0; temp
= XEXP (temp
, 1))
2133 if (unchanging_anti_dependence (r
, XEXP (temp
, 0)))
2135 rtx mem
= XEXP (temp
, 0);
2137 if (rtx_equal_p (XEXP (canon_r
, 0), XEXP (mem
, 0))
2138 && (GET_MODE_SIZE (GET_MODE (canon_r
))
2139 <= GET_MODE_SIZE (GET_MODE (mem
))))
2143 /* Check if memory reference matches an auto increment. Only
2144 post increment/decrement or modify are valid. */
2145 if (GET_MODE (mem
) == GET_MODE (r
)
2146 && (GET_CODE (XEXP (mem
, 0)) == POST_DEC
2147 || GET_CODE (XEXP (mem
, 0)) == POST_INC
2148 || GET_CODE (XEXP (mem
, 0)) == POST_MODIFY
)
2149 && GET_MODE (XEXP (mem
, 0)) == GET_MODE (r
)
2150 && rtx_equal_p (XEXP (XEXP (mem
, 0), 0), XEXP (r
, 0)))
2157 while (GET_CODE (r
) == SUBREG
2158 || GET_CODE (r
) == STRICT_LOW_PART
2159 || GET_CODE (r
) == ZERO_EXTRACT
)
2162 if (GET_CODE (r
) == REG
)
2164 int regno
= REGNO (r
);
2167 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2170 /* If this is a hard register, verify that subsequent
2171 words are not needed. */
2172 if (regno
< FIRST_PSEUDO_REGISTER
)
2174 int n
= HARD_REGNO_NREGS (regno
, GET_MODE (r
));
2177 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
+n
))
2181 /* Don't delete insns to set global regs. */
2182 if (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2185 /* Make sure insns to set the stack pointer aren't deleted. */
2186 if (regno
== STACK_POINTER_REGNUM
)
2189 /* ??? These bits might be redundant with the force live bits
2190 in calculate_global_regs_live. We would delete from
2191 sequential sets; whether this actually affects real code
2192 for anything but the stack pointer I don't know. */
2193 /* Make sure insns to set the frame pointer aren't deleted. */
2194 if (regno
== FRAME_POINTER_REGNUM
2195 && (! reload_completed
|| frame_pointer_needed
))
2197 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2198 if (regno
== HARD_FRAME_POINTER_REGNUM
2199 && (! reload_completed
|| frame_pointer_needed
))
2203 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2204 /* Make sure insns to set arg pointer are never deleted
2205 (if the arg pointer isn't fixed, there will be a USE
2206 for it, so we can treat it normally). */
2207 if (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
2211 /* Otherwise, the set is dead. */
2217 /* If performing several activities, insn is dead if each activity
2218 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2219 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2221 else if (code
== PARALLEL
)
2223 int i
= XVECLEN (x
, 0);
2225 for (i
--; i
>= 0; i
--)
2226 if (GET_CODE (XVECEXP (x
, 0, i
)) != CLOBBER
2227 && GET_CODE (XVECEXP (x
, 0, i
)) != USE
2228 && ! insn_dead_p (pbi
, XVECEXP (x
, 0, i
), call_ok
, NULL_RTX
))
2234 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2235 is not necessarily true for hard registers. */
2236 else if (code
== CLOBBER
&& GET_CODE (XEXP (x
, 0)) == REG
2237 && REGNO (XEXP (x
, 0)) >= FIRST_PSEUDO_REGISTER
2238 && ! REGNO_REG_SET_P (pbi
->reg_live
, REGNO (XEXP (x
, 0))))
2241 /* We do not check other CLOBBER or USE here. An insn consisting of just
2242 a CLOBBER or just a USE should not be deleted. */
2246 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2247 return 1 if the entire library call is dead.
2248 This is true if INSN copies a register (hard or pseudo)
2249 and if the hard return reg of the call insn is dead.
2250 (The caller should have tested the destination of the SET inside
2251 INSN already for death.)
2253 If this insn doesn't just copy a register, then we don't
2254 have an ordinary libcall. In that case, cse could not have
2255 managed to substitute the source for the dest later on,
2256 so we can assume the libcall is dead.
2258 PBI is the block info giving pseudoregs live before this insn.
2259 NOTE is the REG_RETVAL note of the insn. */
2262 libcall_dead_p (struct propagate_block_info
*pbi
, rtx note
, rtx insn
)
2264 rtx x
= single_set (insn
);
2268 rtx r
= SET_SRC (x
);
2270 if (GET_CODE (r
) == REG
)
2272 rtx call
= XEXP (note
, 0);
2276 /* Find the call insn. */
2277 while (call
!= insn
&& GET_CODE (call
) != CALL_INSN
)
2278 call
= NEXT_INSN (call
);
2280 /* If there is none, do nothing special,
2281 since ordinary death handling can understand these insns. */
2285 /* See if the hard reg holding the value is dead.
2286 If this is a PARALLEL, find the call within it. */
2287 call_pat
= PATTERN (call
);
2288 if (GET_CODE (call_pat
) == PARALLEL
)
2290 for (i
= XVECLEN (call_pat
, 0) - 1; i
>= 0; i
--)
2291 if (GET_CODE (XVECEXP (call_pat
, 0, i
)) == SET
2292 && GET_CODE (SET_SRC (XVECEXP (call_pat
, 0, i
))) == CALL
)
2295 /* This may be a library call that is returning a value
2296 via invisible pointer. Do nothing special, since
2297 ordinary death handling can understand these insns. */
2301 call_pat
= XVECEXP (call_pat
, 0, i
);
2304 return insn_dead_p (pbi
, call_pat
, 1, REG_NOTES (call
));
2310 /* Return 1 if register REGNO was used before it was set, i.e. if it is
2311 live at function entry. Don't count global register variables, variables
2312 in registers that can be used for function arg passing, or variables in
2313 fixed hard registers. */
2316 regno_uninitialized (unsigned int regno
)
2318 if (n_basic_blocks
== 0
2319 || (regno
< FIRST_PSEUDO_REGISTER
2320 && (global_regs
[regno
]
2321 || fixed_regs
[regno
]
2322 || FUNCTION_ARG_REGNO_P (regno
))))
2325 return REGNO_REG_SET_P (ENTRY_BLOCK_PTR
->global_live_at_end
, regno
);
2328 /* 1 if register REGNO was alive at a place where `setjmp' was called
2329 and was set more than once or is an argument.
2330 Such regs may be clobbered by `longjmp'. */
2333 regno_clobbered_at_setjmp (int regno
)
2335 if (n_basic_blocks
== 0)
2338 return ((REG_N_SETS (regno
) > 1
2339 || REGNO_REG_SET_P (ENTRY_BLOCK_PTR
->global_live_at_end
, regno
))
2340 && REGNO_REG_SET_P (regs_live_at_setjmp
, regno
));
2343 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2344 maximal list size; look for overlaps in mode and select the largest. */
2346 add_to_mem_set_list (struct propagate_block_info
*pbi
, rtx mem
)
2350 /* We don't know how large a BLKmode store is, so we must not
2351 take them into consideration. */
2352 if (GET_MODE (mem
) == BLKmode
)
2355 for (i
= pbi
->mem_set_list
; i
; i
= XEXP (i
, 1))
2357 rtx e
= XEXP (i
, 0);
2358 if (rtx_equal_p (XEXP (mem
, 0), XEXP (e
, 0)))
2360 if (GET_MODE_SIZE (GET_MODE (mem
)) > GET_MODE_SIZE (GET_MODE (e
)))
2363 /* If we must store a copy of the mem, we can just modify
2364 the mode of the stored copy. */
2365 if (pbi
->flags
& PROP_AUTOINC
)
2366 PUT_MODE (e
, GET_MODE (mem
));
2375 if (pbi
->mem_set_list_len
< MAX_MEM_SET_LIST_LEN
)
2378 /* Store a copy of mem, otherwise the address may be
2379 scrogged by find_auto_inc. */
2380 if (pbi
->flags
& PROP_AUTOINC
)
2381 mem
= shallow_copy_rtx (mem
);
2383 pbi
->mem_set_list
= alloc_EXPR_LIST (0, mem
, pbi
->mem_set_list
);
2384 pbi
->mem_set_list_len
++;
2388 /* INSN references memory, possibly using autoincrement addressing modes.
2389 Find any entries on the mem_set_list that need to be invalidated due
2390 to an address change. */
2393 invalidate_mems_from_autoinc (rtx
*px
, void *data
)
2396 struct propagate_block_info
*pbi
= data
;
2398 if (GET_RTX_CLASS (GET_CODE (x
)) == 'a')
2400 invalidate_mems_from_set (pbi
, XEXP (x
, 0));
2407 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2410 invalidate_mems_from_set (struct propagate_block_info
*pbi
, rtx exp
)
2412 rtx temp
= pbi
->mem_set_list
;
2413 rtx prev
= NULL_RTX
;
2418 next
= XEXP (temp
, 1);
2419 if (reg_overlap_mentioned_p (exp
, XEXP (temp
, 0)))
2421 /* Splice this entry out of the list. */
2423 XEXP (prev
, 1) = next
;
2425 pbi
->mem_set_list
= next
;
2426 free_EXPR_LIST_node (temp
);
2427 pbi
->mem_set_list_len
--;
2435 /* Process the registers that are set within X. Their bits are set to
2436 1 in the regset DEAD, because they are dead prior to this insn.
2438 If INSN is nonzero, it is the insn being processed.
2440 FLAGS is the set of operations to perform. */
2443 mark_set_regs (struct propagate_block_info
*pbi
, rtx x
, rtx insn
)
2445 rtx cond
= NULL_RTX
;
2450 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2452 if (REG_NOTE_KIND (link
) == REG_INC
)
2453 mark_set_1 (pbi
, SET
, XEXP (link
, 0),
2454 (GET_CODE (x
) == COND_EXEC
2455 ? COND_EXEC_TEST (x
) : NULL_RTX
),
2459 switch (code
= GET_CODE (x
))
2463 mark_set_1 (pbi
, code
, SET_DEST (x
), cond
, insn
, pbi
->flags
);
2467 cond
= COND_EXEC_TEST (x
);
2468 x
= COND_EXEC_CODE (x
);
2475 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
2477 rtx sub
= XVECEXP (x
, 0, i
);
2478 switch (code
= GET_CODE (sub
))
2481 if (cond
!= NULL_RTX
)
2484 cond
= COND_EXEC_TEST (sub
);
2485 sub
= COND_EXEC_CODE (sub
);
2486 if (GET_CODE (sub
) != SET
&& GET_CODE (sub
) != CLOBBER
)
2492 mark_set_1 (pbi
, code
, SET_DEST (sub
), cond
, insn
, pbi
->flags
);
2507 /* Process a single set, which appears in INSN. REG (which may not
2508 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2509 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2510 If the set is conditional (because it appear in a COND_EXEC), COND
2511 will be the condition. */
2514 mark_set_1 (struct propagate_block_info
*pbi
, enum rtx_code code
, rtx reg
, rtx cond
, rtx insn
, int flags
)
2516 int regno_first
= -1, regno_last
= -1;
2517 unsigned long not_dead
= 0;
2520 /* Modifying just one hardware register of a multi-reg value or just a
2521 byte field of a register does not mean the value from before this insn
2522 is now dead. Of course, if it was dead after it's unused now. */
2524 switch (GET_CODE (reg
))
2527 /* Some targets place small structures in registers for return values of
2528 functions. We have to detect this case specially here to get correct
2529 flow information. */
2530 for (i
= XVECLEN (reg
, 0) - 1; i
>= 0; i
--)
2531 if (XEXP (XVECEXP (reg
, 0, i
), 0) != 0)
2532 mark_set_1 (pbi
, code
, XEXP (XVECEXP (reg
, 0, i
), 0), cond
, insn
,
2538 case STRICT_LOW_PART
:
2539 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2541 reg
= XEXP (reg
, 0);
2542 while (GET_CODE (reg
) == SUBREG
2543 || GET_CODE (reg
) == ZERO_EXTRACT
2544 || GET_CODE (reg
) == SIGN_EXTRACT
2545 || GET_CODE (reg
) == STRICT_LOW_PART
);
2546 if (GET_CODE (reg
) == MEM
)
2548 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
, REGNO (reg
));
2552 regno_last
= regno_first
= REGNO (reg
);
2553 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2554 regno_last
+= HARD_REGNO_NREGS (regno_first
, GET_MODE (reg
)) - 1;
2558 if (GET_CODE (SUBREG_REG (reg
)) == REG
)
2560 enum machine_mode outer_mode
= GET_MODE (reg
);
2561 enum machine_mode inner_mode
= GET_MODE (SUBREG_REG (reg
));
2563 /* Identify the range of registers affected. This is moderately
2564 tricky for hard registers. See alter_subreg. */
2566 regno_last
= regno_first
= REGNO (SUBREG_REG (reg
));
2567 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2569 regno_first
+= subreg_regno_offset (regno_first
, inner_mode
,
2572 regno_last
= (regno_first
2573 + HARD_REGNO_NREGS (regno_first
, outer_mode
) - 1);
2575 /* Since we've just adjusted the register number ranges, make
2576 sure REG matches. Otherwise some_was_live will be clear
2577 when it shouldn't have been, and we'll create incorrect
2578 REG_UNUSED notes. */
2579 reg
= gen_rtx_REG (outer_mode
, regno_first
);
2583 /* If the number of words in the subreg is less than the number
2584 of words in the full register, we have a well-defined partial
2585 set. Otherwise the high bits are undefined.
2587 This is only really applicable to pseudos, since we just took
2588 care of multi-word hard registers. */
2589 if (((GET_MODE_SIZE (outer_mode
)
2590 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
)
2591 < ((GET_MODE_SIZE (inner_mode
)
2592 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
2593 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
,
2596 reg
= SUBREG_REG (reg
);
2600 reg
= SUBREG_REG (reg
);
2607 /* If this set is a MEM, then it kills any aliased writes.
2608 If this set is a REG, then it kills any MEMs which use the reg. */
2609 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
2611 if (GET_CODE (reg
) == REG
)
2612 invalidate_mems_from_set (pbi
, reg
);
2614 /* If the memory reference had embedded side effects (autoincrement
2615 address modes. Then we may need to kill some entries on the
2617 if (insn
&& GET_CODE (reg
) == MEM
)
2618 for_each_rtx (&PATTERN (insn
), invalidate_mems_from_autoinc
, pbi
);
2620 if (GET_CODE (reg
) == MEM
&& ! side_effects_p (reg
)
2621 /* ??? With more effort we could track conditional memory life. */
2623 add_to_mem_set_list (pbi
, canon_rtx (reg
));
2626 if (GET_CODE (reg
) == REG
2627 && ! (regno_first
== FRAME_POINTER_REGNUM
2628 && (! reload_completed
|| frame_pointer_needed
))
2629 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2630 && ! (regno_first
== HARD_FRAME_POINTER_REGNUM
2631 && (! reload_completed
|| frame_pointer_needed
))
2633 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2634 && ! (regno_first
== ARG_POINTER_REGNUM
&& fixed_regs
[regno_first
])
2638 int some_was_live
= 0, some_was_dead
= 0;
2640 for (i
= regno_first
; i
<= regno_last
; ++i
)
2642 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
2645 /* Order of the set operation matters here since both
2646 sets may be the same. */
2647 CLEAR_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2648 if (cond
!= NULL_RTX
2649 && ! REGNO_REG_SET_P (pbi
->local_set
, i
))
2650 SET_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2652 SET_REGNO_REG_SET (pbi
->local_set
, i
);
2654 if (code
!= CLOBBER
)
2655 SET_REGNO_REG_SET (pbi
->new_set
, i
);
2657 some_was_live
|= needed_regno
;
2658 some_was_dead
|= ! needed_regno
;
2661 #ifdef HAVE_conditional_execution
2662 /* Consider conditional death in deciding that the register needs
2664 if (some_was_live
&& ! not_dead
2665 /* The stack pointer is never dead. Well, not strictly true,
2666 but it's very difficult to tell from here. Hopefully
2667 combine_stack_adjustments will fix up the most egregious
2669 && regno_first
!= STACK_POINTER_REGNUM
)
2671 for (i
= regno_first
; i
<= regno_last
; ++i
)
2672 if (! mark_regno_cond_dead (pbi
, i
, cond
))
2673 not_dead
|= ((unsigned long) 1) << (i
- regno_first
);
2677 /* Additional data to record if this is the final pass. */
2678 if (flags
& (PROP_LOG_LINKS
| PROP_REG_INFO
2679 | PROP_DEATH_NOTES
| PROP_AUTOINC
))
2682 int blocknum
= pbi
->bb
->index
;
2685 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2687 y
= pbi
->reg_next_use
[regno_first
];
2689 /* The next use is no longer next, since a store intervenes. */
2690 for (i
= regno_first
; i
<= regno_last
; ++i
)
2691 pbi
->reg_next_use
[i
] = 0;
2694 if (flags
& PROP_REG_INFO
)
2696 for (i
= regno_first
; i
<= regno_last
; ++i
)
2698 /* Count (weighted) references, stores, etc. This counts a
2699 register twice if it is modified, but that is correct. */
2700 REG_N_SETS (i
) += 1;
2701 REG_N_REFS (i
) += 1;
2702 REG_FREQ (i
) += REG_FREQ_FROM_BB (pbi
->bb
);
2704 /* The insns where a reg is live are normally counted
2705 elsewhere, but we want the count to include the insn
2706 where the reg is set, and the normal counting mechanism
2707 would not count it. */
2708 REG_LIVE_LENGTH (i
) += 1;
2711 /* If this is a hard reg, record this function uses the reg. */
2712 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2714 for (i
= regno_first
; i
<= regno_last
; i
++)
2715 regs_ever_live
[i
] = 1;
2719 /* Keep track of which basic blocks each reg appears in. */
2720 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
2721 REG_BASIC_BLOCK (regno_first
) = blocknum
;
2722 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
2723 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
2727 if (! some_was_dead
)
2729 if (flags
& PROP_LOG_LINKS
)
2731 /* Make a logical link from the next following insn
2732 that uses this register, back to this insn.
2733 The following insns have already been processed.
2735 We don't build a LOG_LINK for hard registers containing
2736 in ASM_OPERANDs. If these registers get replaced,
2737 we might wind up changing the semantics of the insn,
2738 even if reload can make what appear to be valid
2739 assignments later. */
2740 if (y
&& (BLOCK_NUM (y
) == blocknum
)
2741 && (regno_first
>= FIRST_PSEUDO_REGISTER
2742 || asm_noperands (PATTERN (y
)) < 0))
2743 LOG_LINKS (y
) = alloc_INSN_LIST (insn
, LOG_LINKS (y
));
2748 else if (! some_was_live
)
2750 if (flags
& PROP_REG_INFO
)
2751 REG_N_DEATHS (regno_first
) += 1;
2753 if (flags
& PROP_DEATH_NOTES
)
2755 /* Note that dead stores have already been deleted
2756 when possible. If we get here, we have found a
2757 dead store that cannot be eliminated (because the
2758 same insn does something useful). Indicate this
2759 by marking the reg being set as dying here. */
2761 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2766 if (flags
& PROP_DEATH_NOTES
)
2768 /* This is a case where we have a multi-word hard register
2769 and some, but not all, of the words of the register are
2770 needed in subsequent insns. Write REG_UNUSED notes
2771 for those parts that were not needed. This case should
2774 for (i
= regno_first
; i
<= regno_last
; ++i
)
2775 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
))
2777 = alloc_EXPR_LIST (REG_UNUSED
,
2784 /* Mark the register as being dead. */
2786 /* The stack pointer is never dead. Well, not strictly true,
2787 but it's very difficult to tell from here. Hopefully
2788 combine_stack_adjustments will fix up the most egregious
2790 && regno_first
!= STACK_POINTER_REGNUM
)
2792 for (i
= regno_first
; i
<= regno_last
; ++i
)
2793 if (!(not_dead
& (((unsigned long) 1) << (i
- regno_first
))))
2794 CLEAR_REGNO_REG_SET (pbi
->reg_live
, i
);
2797 else if (GET_CODE (reg
) == REG
)
2799 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2800 pbi
->reg_next_use
[regno_first
] = 0;
2803 /* If this is the last pass and this is a SCRATCH, show it will be dying
2804 here and count it. */
2805 else if (GET_CODE (reg
) == SCRATCH
)
2807 if (flags
& PROP_DEATH_NOTES
)
2809 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2813 #ifdef HAVE_conditional_execution
2814 /* Mark REGNO conditionally dead.
2815 Return true if the register is now unconditionally dead. */
2818 mark_regno_cond_dead (struct propagate_block_info
*pbi
, int regno
, rtx cond
)
2820 /* If this is a store to a predicate register, the value of the
2821 predicate is changing, we don't know that the predicate as seen
2822 before is the same as that seen after. Flush all dependent
2823 conditions from reg_cond_dead. This will make all such
2824 conditionally live registers unconditionally live. */
2825 if (REGNO_REG_SET_P (pbi
->reg_cond_reg
, regno
))
2826 flush_reg_cond_reg (pbi
, regno
);
2828 /* If this is an unconditional store, remove any conditional
2829 life that may have existed. */
2830 if (cond
== NULL_RTX
)
2831 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2834 splay_tree_node node
;
2835 struct reg_cond_life_info
*rcli
;
2838 /* Otherwise this is a conditional set. Record that fact.
2839 It may have been conditionally used, or there may be a
2840 subsequent set with a complimentary condition. */
2842 node
= splay_tree_lookup (pbi
->reg_cond_dead
, regno
);
2845 /* The register was unconditionally live previously.
2846 Record the current condition as the condition under
2847 which it is dead. */
2848 rcli
= xmalloc (sizeof (*rcli
));
2849 rcli
->condition
= cond
;
2850 rcli
->stores
= cond
;
2851 rcli
->orig_condition
= const0_rtx
;
2852 splay_tree_insert (pbi
->reg_cond_dead
, regno
,
2853 (splay_tree_value
) rcli
);
2855 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2857 /* Not unconditionally dead. */
2862 /* The register was conditionally live previously.
2863 Add the new condition to the old. */
2864 rcli
= (struct reg_cond_life_info
*) node
->value
;
2865 ncond
= rcli
->condition
;
2866 ncond
= ior_reg_cond (ncond
, cond
, 1);
2867 if (rcli
->stores
== const0_rtx
)
2868 rcli
->stores
= cond
;
2869 else if (rcli
->stores
!= const1_rtx
)
2870 rcli
->stores
= ior_reg_cond (rcli
->stores
, cond
, 1);
2872 /* If the register is now unconditionally dead, remove the entry
2873 in the splay_tree. A register is unconditionally dead if the
2874 dead condition ncond is true. A register is also unconditionally
2875 dead if the sum of all conditional stores is an unconditional
2876 store (stores is true), and the dead condition is identically the
2877 same as the original dead condition initialized at the end of
2878 the block. This is a pointer compare, not an rtx_equal_p
2880 if (ncond
== const1_rtx
2881 || (ncond
== rcli
->orig_condition
&& rcli
->stores
== const1_rtx
))
2882 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2885 rcli
->condition
= ncond
;
2887 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2889 /* Not unconditionally dead. */
2898 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2901 free_reg_cond_life_info (splay_tree_value value
)
2903 struct reg_cond_life_info
*rcli
= (struct reg_cond_life_info
*) value
;
2907 /* Helper function for flush_reg_cond_reg. */
2910 flush_reg_cond_reg_1 (splay_tree_node node
, void *data
)
2912 struct reg_cond_life_info
*rcli
;
2913 int *xdata
= (int *) data
;
2914 unsigned int regno
= xdata
[0];
2916 /* Don't need to search if last flushed value was farther on in
2917 the in-order traversal. */
2918 if (xdata
[1] >= (int) node
->key
)
2921 /* Splice out portions of the expression that refer to regno. */
2922 rcli
= (struct reg_cond_life_info
*) node
->value
;
2923 rcli
->condition
= elim_reg_cond (rcli
->condition
, regno
);
2924 if (rcli
->stores
!= const0_rtx
&& rcli
->stores
!= const1_rtx
)
2925 rcli
->stores
= elim_reg_cond (rcli
->stores
, regno
);
2927 /* If the entire condition is now false, signal the node to be removed. */
2928 if (rcli
->condition
== const0_rtx
)
2930 xdata
[1] = node
->key
;
2933 else if (rcli
->condition
== const1_rtx
)
2939 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2942 flush_reg_cond_reg (struct propagate_block_info
*pbi
, int regno
)
2948 while (splay_tree_foreach (pbi
->reg_cond_dead
,
2949 flush_reg_cond_reg_1
, pair
) == -1)
2950 splay_tree_remove (pbi
->reg_cond_dead
, pair
[1]);
2952 CLEAR_REGNO_REG_SET (pbi
->reg_cond_reg
, regno
);
2955 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2956 For ior/and, the ADD flag determines whether we want to add the new
2957 condition X to the old one unconditionally. If it is zero, we will
2958 only return a new expression if X allows us to simplify part of
2959 OLD, otherwise we return NULL to the caller.
2960 If ADD is nonzero, we will return a new condition in all cases. The
2961 toplevel caller of one of these functions should always pass 1 for
2965 ior_reg_cond (rtx old
, rtx x
, int add
)
2969 if (GET_RTX_CLASS (GET_CODE (old
)) == '<')
2971 if (GET_RTX_CLASS (GET_CODE (x
)) == '<'
2972 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x
), GET_CODE (old
))
2973 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
2975 if (GET_CODE (x
) == GET_CODE (old
)
2976 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
2980 return gen_rtx_IOR (0, old
, x
);
2983 switch (GET_CODE (old
))
2986 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
2987 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
2988 if (op0
!= NULL
|| op1
!= NULL
)
2990 if (op0
== const0_rtx
)
2991 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
2992 if (op1
== const0_rtx
)
2993 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
2994 if (op0
== const1_rtx
|| op1
== const1_rtx
)
2997 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
2998 else if (rtx_equal_p (x
, op0
))
2999 /* (x | A) | x ~ (x | A). */
3002 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3003 else if (rtx_equal_p (x
, op1
))
3004 /* (A | x) | x ~ (A | x). */
3006 return gen_rtx_IOR (0, op0
, op1
);
3010 return gen_rtx_IOR (0, old
, x
);
3013 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
3014 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
3015 if (op0
!= NULL
|| op1
!= NULL
)
3017 if (op0
== const1_rtx
)
3018 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
3019 if (op1
== const1_rtx
)
3020 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
3021 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3024 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
3025 else if (rtx_equal_p (x
, op0
))
3026 /* (x & A) | x ~ x. */
3029 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3030 else if (rtx_equal_p (x
, op1
))
3031 /* (A & x) | x ~ x. */
3033 return gen_rtx_AND (0, op0
, op1
);
3037 return gen_rtx_IOR (0, old
, x
);
3040 op0
= and_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3042 return not_reg_cond (op0
);
3045 return gen_rtx_IOR (0, old
, x
);
3053 not_reg_cond (rtx x
)
3055 enum rtx_code x_code
;
3057 if (x
== const0_rtx
)
3059 else if (x
== const1_rtx
)
3061 x_code
= GET_CODE (x
);
3064 if (GET_RTX_CLASS (x_code
) == '<'
3065 && GET_CODE (XEXP (x
, 0)) == REG
)
3067 if (XEXP (x
, 1) != const0_rtx
)
3070 return gen_rtx_fmt_ee (reverse_condition (x_code
),
3071 VOIDmode
, XEXP (x
, 0), const0_rtx
);
3073 return gen_rtx_NOT (0, x
);
3077 and_reg_cond (rtx old
, rtx x
, int add
)
3081 if (GET_RTX_CLASS (GET_CODE (old
)) == '<')
3083 if (GET_RTX_CLASS (GET_CODE (x
)) == '<'
3084 && GET_CODE (x
) == reverse_condition (GET_CODE (old
))
3085 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3087 if (GET_CODE (x
) == GET_CODE (old
)
3088 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3092 return gen_rtx_AND (0, old
, x
);
3095 switch (GET_CODE (old
))
3098 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3099 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3100 if (op0
!= NULL
|| op1
!= NULL
)
3102 if (op0
== const0_rtx
)
3103 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3104 if (op1
== const0_rtx
)
3105 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3106 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3109 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3110 else if (rtx_equal_p (x
, op0
))
3111 /* (x | A) & x ~ x. */
3114 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3115 else if (rtx_equal_p (x
, op1
))
3116 /* (A | x) & x ~ x. */
3118 return gen_rtx_IOR (0, op0
, op1
);
3122 return gen_rtx_AND (0, old
, x
);
3125 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3126 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3127 if (op0
!= NULL
|| op1
!= NULL
)
3129 if (op0
== const1_rtx
)
3130 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3131 if (op1
== const1_rtx
)
3132 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3133 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3136 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3137 else if (rtx_equal_p (x
, op0
))
3138 /* (x & A) & x ~ (x & A). */
3141 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3142 else if (rtx_equal_p (x
, op1
))
3143 /* (A & x) & x ~ (A & x). */
3145 return gen_rtx_AND (0, op0
, op1
);
3149 return gen_rtx_AND (0, old
, x
);
3152 op0
= ior_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3154 return not_reg_cond (op0
);
3157 return gen_rtx_AND (0, old
, x
);
3164 /* Given a condition X, remove references to reg REGNO and return the
3165 new condition. The removal will be done so that all conditions
3166 involving REGNO are considered to evaluate to false. This function
3167 is used when the value of REGNO changes. */
3170 elim_reg_cond (rtx x
, unsigned int regno
)
3174 if (GET_RTX_CLASS (GET_CODE (x
)) == '<')
3176 if (REGNO (XEXP (x
, 0)) == regno
)
3181 switch (GET_CODE (x
))
3184 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3185 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3186 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3188 if (op0
== const1_rtx
)
3190 if (op1
== const1_rtx
)
3192 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3194 return gen_rtx_AND (0, op0
, op1
);
3197 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3198 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3199 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3201 if (op0
== const0_rtx
)
3203 if (op1
== const0_rtx
)
3205 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3207 return gen_rtx_IOR (0, op0
, op1
);
3210 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3211 if (op0
== const0_rtx
)
3213 if (op0
== const1_rtx
)
3215 if (op0
!= XEXP (x
, 0))
3216 return not_reg_cond (op0
);
3223 #endif /* HAVE_conditional_execution */
3227 /* Try to substitute the auto-inc expression INC as the address inside
3228 MEM which occurs in INSN. Currently, the address of MEM is an expression
3229 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3230 that has a single set whose source is a PLUS of INCR_REG and something
3234 attempt_auto_inc (struct propagate_block_info
*pbi
, rtx inc
, rtx insn
,
3235 rtx mem
, rtx incr
, rtx incr_reg
)
3237 int regno
= REGNO (incr_reg
);
3238 rtx set
= single_set (incr
);
3239 rtx q
= SET_DEST (set
);
3240 rtx y
= SET_SRC (set
);
3241 int opnum
= XEXP (y
, 0) == incr_reg
? 0 : 1;
3243 /* Make sure this reg appears only once in this insn. */
3244 if (count_occurrences (PATTERN (insn
), incr_reg
, 1) != 1)
3247 if (dead_or_set_p (incr
, incr_reg
)
3248 /* Mustn't autoinc an eliminable register. */
3249 && (regno
>= FIRST_PSEUDO_REGISTER
3250 || ! TEST_HARD_REG_BIT (elim_reg_set
, regno
)))
3252 /* This is the simple case. Try to make the auto-inc. If
3253 we can't, we are done. Otherwise, we will do any
3254 needed updates below. */
3255 if (! validate_change (insn
, &XEXP (mem
, 0), inc
, 0))
3258 else if (GET_CODE (q
) == REG
3259 /* PREV_INSN used here to check the semi-open interval
3261 && ! reg_used_between_p (q
, PREV_INSN (insn
), incr
)
3262 /* We must also check for sets of q as q may be
3263 a call clobbered hard register and there may
3264 be a call between PREV_INSN (insn) and incr. */
3265 && ! reg_set_between_p (q
, PREV_INSN (insn
), incr
))
3267 /* We have *p followed sometime later by q = p+size.
3268 Both p and q must be live afterward,
3269 and q is not used between INSN and its assignment.
3270 Change it to q = p, ...*q..., q = q+size.
3271 Then fall into the usual case. */
3275 emit_move_insn (q
, incr_reg
);
3276 insns
= get_insns ();
3279 /* If we can't make the auto-inc, or can't make the
3280 replacement into Y, exit. There's no point in making
3281 the change below if we can't do the auto-inc and doing
3282 so is not correct in the pre-inc case. */
3285 validate_change (insn
, &XEXP (mem
, 0), inc
, 1);
3286 validate_change (incr
, &XEXP (y
, opnum
), q
, 1);
3287 if (! apply_change_group ())
3290 /* We now know we'll be doing this change, so emit the
3291 new insn(s) and do the updates. */
3292 emit_insn_before (insns
, insn
);
3294 if (pbi
->bb
->head
== insn
)
3295 pbi
->bb
->head
= insns
;
3297 /* INCR will become a NOTE and INSN won't contain a
3298 use of INCR_REG. If a use of INCR_REG was just placed in
3299 the insn before INSN, make that the next use.
3300 Otherwise, invalidate it. */
3301 if (GET_CODE (PREV_INSN (insn
)) == INSN
3302 && GET_CODE (PATTERN (PREV_INSN (insn
))) == SET
3303 && SET_SRC (PATTERN (PREV_INSN (insn
))) == incr_reg
)
3304 pbi
->reg_next_use
[regno
] = PREV_INSN (insn
);
3306 pbi
->reg_next_use
[regno
] = 0;
3311 /* REGNO is now used in INCR which is below INSN, but
3312 it previously wasn't live here. If we don't mark
3313 it as live, we'll put a REG_DEAD note for it
3314 on this insn, which is incorrect. */
3315 SET_REGNO_REG_SET (pbi
->reg_live
, regno
);
3317 /* If there are any calls between INSN and INCR, show
3318 that REGNO now crosses them. */
3319 for (temp
= insn
; temp
!= incr
; temp
= NEXT_INSN (temp
))
3320 if (GET_CODE (temp
) == CALL_INSN
)
3321 REG_N_CALLS_CROSSED (regno
)++;
3323 /* Invalidate alias info for Q since we just changed its value. */
3324 clear_reg_alias_info (q
);
3329 /* If we haven't returned, it means we were able to make the
3330 auto-inc, so update the status. First, record that this insn
3331 has an implicit side effect. */
3333 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, incr_reg
, REG_NOTES (insn
));
3335 /* Modify the old increment-insn to simply copy
3336 the already-incremented value of our register. */
3337 if (! validate_change (incr
, &SET_SRC (set
), incr_reg
, 0))
3340 /* If that makes it a no-op (copying the register into itself) delete
3341 it so it won't appear to be a "use" and a "set" of this
3343 if (REGNO (SET_DEST (set
)) == REGNO (incr_reg
))
3345 /* If the original source was dead, it's dead now. */
3348 while ((note
= find_reg_note (incr
, REG_DEAD
, NULL_RTX
)) != NULL_RTX
)
3350 remove_note (incr
, note
);
3351 if (XEXP (note
, 0) != incr_reg
)
3352 CLEAR_REGNO_REG_SET (pbi
->reg_live
, REGNO (XEXP (note
, 0)));
3355 PUT_CODE (incr
, NOTE
);
3356 NOTE_LINE_NUMBER (incr
) = NOTE_INSN_DELETED
;
3357 NOTE_SOURCE_FILE (incr
) = 0;
3360 if (regno
>= FIRST_PSEUDO_REGISTER
)
3362 /* Count an extra reference to the reg. When a reg is
3363 incremented, spilling it is worse, so we want to make
3364 that less likely. */
3365 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
3367 /* Count the increment as a setting of the register,
3368 even though it isn't a SET in rtl. */
3369 REG_N_SETS (regno
)++;
3373 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3377 find_auto_inc (struct propagate_block_info
*pbi
, rtx x
, rtx insn
)
3379 rtx addr
= XEXP (x
, 0);
3380 HOST_WIDE_INT offset
= 0;
3381 rtx set
, y
, incr
, inc_val
;
3383 int size
= GET_MODE_SIZE (GET_MODE (x
));
3385 if (GET_CODE (insn
) == JUMP_INSN
)
3388 /* Here we detect use of an index register which might be good for
3389 postincrement, postdecrement, preincrement, or predecrement. */
3391 if (GET_CODE (addr
) == PLUS
&& GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
3392 offset
= INTVAL (XEXP (addr
, 1)), addr
= XEXP (addr
, 0);
3394 if (GET_CODE (addr
) != REG
)
3397 regno
= REGNO (addr
);
3399 /* Is the next use an increment that might make auto-increment? */
3400 incr
= pbi
->reg_next_use
[regno
];
3401 if (incr
== 0 || BLOCK_NUM (incr
) != BLOCK_NUM (insn
))
3403 set
= single_set (incr
);
3404 if (set
== 0 || GET_CODE (set
) != SET
)
3408 if (GET_CODE (y
) != PLUS
)
3411 if (REG_P (XEXP (y
, 0)) && REGNO (XEXP (y
, 0)) == REGNO (addr
))
3412 inc_val
= XEXP (y
, 1);
3413 else if (REG_P (XEXP (y
, 1)) && REGNO (XEXP (y
, 1)) == REGNO (addr
))
3414 inc_val
= XEXP (y
, 0);
3418 if (GET_CODE (inc_val
) == CONST_INT
)
3420 if (HAVE_POST_INCREMENT
3421 && (INTVAL (inc_val
) == size
&& offset
== 0))
3422 attempt_auto_inc (pbi
, gen_rtx_POST_INC (Pmode
, addr
), insn
, x
,
3424 else if (HAVE_POST_DECREMENT
3425 && (INTVAL (inc_val
) == -size
&& offset
== 0))
3426 attempt_auto_inc (pbi
, gen_rtx_POST_DEC (Pmode
, addr
), insn
, x
,
3428 else if (HAVE_PRE_INCREMENT
3429 && (INTVAL (inc_val
) == size
&& offset
== size
))
3430 attempt_auto_inc (pbi
, gen_rtx_PRE_INC (Pmode
, addr
), insn
, x
,
3432 else if (HAVE_PRE_DECREMENT
3433 && (INTVAL (inc_val
) == -size
&& offset
== -size
))
3434 attempt_auto_inc (pbi
, gen_rtx_PRE_DEC (Pmode
, addr
), insn
, x
,
3436 else if (HAVE_POST_MODIFY_DISP
&& offset
== 0)
3437 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3438 gen_rtx_PLUS (Pmode
,
3441 insn
, x
, incr
, addr
);
3442 else if (HAVE_PRE_MODIFY_DISP
&& offset
== INTVAL (inc_val
))
3443 attempt_auto_inc (pbi
, gen_rtx_PRE_MODIFY (Pmode
, addr
,
3444 gen_rtx_PLUS (Pmode
,
3447 insn
, x
, incr
, addr
);
3449 else if (GET_CODE (inc_val
) == REG
3450 && ! reg_set_between_p (inc_val
, PREV_INSN (insn
),
3454 if (HAVE_POST_MODIFY_REG
&& offset
== 0)
3455 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3456 gen_rtx_PLUS (Pmode
,
3459 insn
, x
, incr
, addr
);
3463 #endif /* AUTO_INC_DEC */
3466 mark_used_reg (struct propagate_block_info
*pbi
, rtx reg
,
3467 rtx cond ATTRIBUTE_UNUSED
, rtx insn
)
3469 unsigned int regno_first
, regno_last
, i
;
3470 int some_was_live
, some_was_dead
, some_not_set
;
3472 regno_last
= regno_first
= REGNO (reg
);
3473 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3474 regno_last
+= HARD_REGNO_NREGS (regno_first
, GET_MODE (reg
)) - 1;
3476 /* Find out if any of this register is live after this instruction. */
3477 some_was_live
= some_was_dead
= 0;
3478 for (i
= regno_first
; i
<= regno_last
; ++i
)
3480 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3481 some_was_live
|= needed_regno
;
3482 some_was_dead
|= ! needed_regno
;
3485 /* Find out if any of the register was set this insn. */
3487 for (i
= regno_first
; i
<= regno_last
; ++i
)
3488 some_not_set
|= ! REGNO_REG_SET_P (pbi
->new_set
, i
);
3490 if (pbi
->flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
3492 /* Record where each reg is used, so when the reg is set we know
3493 the next insn that uses it. */
3494 pbi
->reg_next_use
[regno_first
] = insn
;
3497 if (pbi
->flags
& PROP_REG_INFO
)
3499 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3501 /* If this is a register we are going to try to eliminate,
3502 don't mark it live here. If we are successful in
3503 eliminating it, it need not be live unless it is used for
3504 pseudos, in which case it will have been set live when it
3505 was allocated to the pseudos. If the register will not
3506 be eliminated, reload will set it live at that point.
3508 Otherwise, record that this function uses this register. */
3509 /* ??? The PPC backend tries to "eliminate" on the pic
3510 register to itself. This should be fixed. In the mean
3511 time, hack around it. */
3513 if (! (TEST_HARD_REG_BIT (elim_reg_set
, regno_first
)
3514 && (regno_first
== FRAME_POINTER_REGNUM
3515 || regno_first
== ARG_POINTER_REGNUM
)))
3516 for (i
= regno_first
; i
<= regno_last
; ++i
)
3517 regs_ever_live
[i
] = 1;
3521 /* Keep track of which basic block each reg appears in. */
3523 int blocknum
= pbi
->bb
->index
;
3524 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
3525 REG_BASIC_BLOCK (regno_first
) = blocknum
;
3526 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
3527 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
3529 /* Count (weighted) number of uses of each reg. */
3530 REG_FREQ (regno_first
) += REG_FREQ_FROM_BB (pbi
->bb
);
3531 REG_N_REFS (regno_first
)++;
3535 /* Record and count the insns in which a reg dies. If it is used in
3536 this insn and was dead below the insn then it dies in this insn.
3537 If it was set in this insn, we do not make a REG_DEAD note;
3538 likewise if we already made such a note. */
3539 if ((pbi
->flags
& (PROP_DEATH_NOTES
| PROP_REG_INFO
))
3543 /* Check for the case where the register dying partially
3544 overlaps the register set by this insn. */
3545 if (regno_first
!= regno_last
)
3546 for (i
= regno_first
; i
<= regno_last
; ++i
)
3547 some_was_live
|= REGNO_REG_SET_P (pbi
->new_set
, i
);
3549 /* If none of the words in X is needed, make a REG_DEAD note.
3550 Otherwise, we must make partial REG_DEAD notes. */
3551 if (! some_was_live
)
3553 if ((pbi
->flags
& PROP_DEATH_NOTES
)
3554 && ! find_regno_note (insn
, REG_DEAD
, regno_first
))
3556 = alloc_EXPR_LIST (REG_DEAD
, reg
, REG_NOTES (insn
));
3558 if (pbi
->flags
& PROP_REG_INFO
)
3559 REG_N_DEATHS (regno_first
)++;
3563 /* Don't make a REG_DEAD note for a part of a register
3564 that is set in the insn. */
3565 for (i
= regno_first
; i
<= regno_last
; ++i
)
3566 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
)
3567 && ! dead_or_set_regno_p (insn
, i
))
3569 = alloc_EXPR_LIST (REG_DEAD
,
3575 /* Mark the register as being live. */
3576 for (i
= regno_first
; i
<= regno_last
; ++i
)
3578 #ifdef HAVE_conditional_execution
3579 int this_was_live
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3582 SET_REGNO_REG_SET (pbi
->reg_live
, i
);
3584 #ifdef HAVE_conditional_execution
3585 /* If this is a conditional use, record that fact. If it is later
3586 conditionally set, we'll know to kill the register. */
3587 if (cond
!= NULL_RTX
)
3589 splay_tree_node node
;
3590 struct reg_cond_life_info
*rcli
;
3595 node
= splay_tree_lookup (pbi
->reg_cond_dead
, i
);
3598 /* The register was unconditionally live previously.
3599 No need to do anything. */
3603 /* The register was conditionally live previously.
3604 Subtract the new life cond from the old death cond. */
3605 rcli
= (struct reg_cond_life_info
*) node
->value
;
3606 ncond
= rcli
->condition
;
3607 ncond
= and_reg_cond (ncond
, not_reg_cond (cond
), 1);
3609 /* If the register is now unconditionally live,
3610 remove the entry in the splay_tree. */
3611 if (ncond
== const0_rtx
)
3612 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3615 rcli
->condition
= ncond
;
3616 SET_REGNO_REG_SET (pbi
->reg_cond_reg
,
3617 REGNO (XEXP (cond
, 0)));
3623 /* The register was not previously live at all. Record
3624 the condition under which it is still dead. */
3625 rcli
= xmalloc (sizeof (*rcli
));
3626 rcli
->condition
= not_reg_cond (cond
);
3627 rcli
->stores
= const0_rtx
;
3628 rcli
->orig_condition
= const0_rtx
;
3629 splay_tree_insert (pbi
->reg_cond_dead
, i
,
3630 (splay_tree_value
) rcli
);
3632 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
3635 else if (this_was_live
)
3637 /* The register may have been conditionally live previously, but
3638 is now unconditionally live. Remove it from the conditionally
3639 dead list, so that a conditional set won't cause us to think
3641 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3647 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3648 This is done assuming the registers needed from X are those that
3649 have 1-bits in PBI->REG_LIVE.
3651 INSN is the containing instruction. If INSN is dead, this function
3655 mark_used_regs (struct propagate_block_info
*pbi
, rtx x
, rtx cond
, rtx insn
)
3659 int flags
= pbi
->flags
;
3664 code
= GET_CODE (x
);
3685 /* If we are clobbering a MEM, mark any registers inside the address
3687 if (GET_CODE (XEXP (x
, 0)) == MEM
)
3688 mark_used_regs (pbi
, XEXP (XEXP (x
, 0), 0), cond
, insn
);
3692 /* Don't bother watching stores to mems if this is not the
3693 final pass. We'll not be deleting dead stores this round. */
3694 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
3696 /* Invalidate the data for the last MEM stored, but only if MEM is
3697 something that can be stored into. */
3698 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
3699 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
3700 /* Needn't clear the memory set list. */
3704 rtx temp
= pbi
->mem_set_list
;
3705 rtx prev
= NULL_RTX
;
3710 next
= XEXP (temp
, 1);
3711 if (unchanging_anti_dependence (XEXP (temp
, 0), x
))
3713 /* Splice temp out of the list. */
3715 XEXP (prev
, 1) = next
;
3717 pbi
->mem_set_list
= next
;
3718 free_EXPR_LIST_node (temp
);
3719 pbi
->mem_set_list_len
--;
3727 /* If the memory reference had embedded side effects (autoincrement
3728 address modes. Then we may need to kill some entries on the
3731 for_each_rtx (&PATTERN (insn
), invalidate_mems_from_autoinc
, pbi
);
3735 if (flags
& PROP_AUTOINC
)
3736 find_auto_inc (pbi
, x
, insn
);
3741 #ifdef CANNOT_CHANGE_MODE_CLASS
3742 if ((flags
& PROP_REG_INFO
)
3743 && GET_CODE (SUBREG_REG (x
)) == REG
3744 && REGNO (SUBREG_REG (x
)) >= FIRST_PSEUDO_REGISTER
)
3745 bitmap_set_bit (&subregs_of_mode
, REGNO (SUBREG_REG (x
))
3750 /* While we're here, optimize this case. */
3752 if (GET_CODE (x
) != REG
)
3757 /* See a register other than being set => mark it as needed. */
3758 mark_used_reg (pbi
, x
, cond
, insn
);
3763 rtx testreg
= SET_DEST (x
);
3766 /* If storing into MEM, don't show it as being used. But do
3767 show the address as being used. */
3768 if (GET_CODE (testreg
) == MEM
)
3771 if (flags
& PROP_AUTOINC
)
3772 find_auto_inc (pbi
, testreg
, insn
);
3774 mark_used_regs (pbi
, XEXP (testreg
, 0), cond
, insn
);
3775 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3779 /* Storing in STRICT_LOW_PART is like storing in a reg
3780 in that this SET might be dead, so ignore it in TESTREG.
3781 but in some other ways it is like using the reg.
3783 Storing in a SUBREG or a bit field is like storing the entire
3784 register in that if the register's value is not used
3785 then this SET is not needed. */
3786 while (GET_CODE (testreg
) == STRICT_LOW_PART
3787 || GET_CODE (testreg
) == ZERO_EXTRACT
3788 || GET_CODE (testreg
) == SIGN_EXTRACT
3789 || GET_CODE (testreg
) == SUBREG
)
3791 #ifdef CANNOT_CHANGE_MODE_CLASS
3792 if ((flags
& PROP_REG_INFO
)
3793 && GET_CODE (testreg
) == SUBREG
3794 && GET_CODE (SUBREG_REG (testreg
)) == REG
3795 && REGNO (SUBREG_REG (testreg
)) >= FIRST_PSEUDO_REGISTER
)
3796 bitmap_set_bit (&subregs_of_mode
, REGNO (SUBREG_REG (testreg
))
3798 + GET_MODE (testreg
));
3801 /* Modifying a single register in an alternate mode
3802 does not use any of the old value. But these other
3803 ways of storing in a register do use the old value. */
3804 if (GET_CODE (testreg
) == SUBREG
3805 && !((REG_BYTES (SUBREG_REG (testreg
))
3806 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
3807 > (REG_BYTES (testreg
)
3808 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
3813 testreg
= XEXP (testreg
, 0);
3816 /* If this is a store into a register or group of registers,
3817 recursively scan the value being stored. */
3819 if ((GET_CODE (testreg
) == PARALLEL
3820 && GET_MODE (testreg
) == BLKmode
)
3821 || (GET_CODE (testreg
) == REG
3822 && (regno
= REGNO (testreg
),
3823 ! (regno
== FRAME_POINTER_REGNUM
3824 && (! reload_completed
|| frame_pointer_needed
)))
3825 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3826 && ! (regno
== HARD_FRAME_POINTER_REGNUM
3827 && (! reload_completed
|| frame_pointer_needed
))
3829 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3830 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
3835 mark_used_regs (pbi
, SET_DEST (x
), cond
, insn
);
3836 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3843 case UNSPEC_VOLATILE
:
3847 /* Traditional and volatile asm instructions must be considered to use
3848 and clobber all hard registers, all pseudo-registers and all of
3849 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3851 Consider for instance a volatile asm that changes the fpu rounding
3852 mode. An insn should not be moved across this even if it only uses
3853 pseudo-regs because it might give an incorrectly rounded result.
3855 ?!? Unfortunately, marking all hard registers as live causes massive
3856 problems for the register allocator and marking all pseudos as live
3857 creates mountains of uninitialized variable warnings.
3859 So for now, just clear the memory set list and mark any regs
3860 we can find in ASM_OPERANDS as used. */
3861 if (code
!= ASM_OPERANDS
|| MEM_VOLATILE_P (x
))
3863 free_EXPR_LIST_list (&pbi
->mem_set_list
);
3864 pbi
->mem_set_list_len
= 0;
3867 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3868 We can not just fall through here since then we would be confused
3869 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3870 traditional asms unlike their normal usage. */
3871 if (code
== ASM_OPERANDS
)
3875 for (j
= 0; j
< ASM_OPERANDS_INPUT_LENGTH (x
); j
++)
3876 mark_used_regs (pbi
, ASM_OPERANDS_INPUT (x
, j
), cond
, insn
);
3882 if (cond
!= NULL_RTX
)
3885 mark_used_regs (pbi
, COND_EXEC_TEST (x
), NULL_RTX
, insn
);
3887 cond
= COND_EXEC_TEST (x
);
3888 x
= COND_EXEC_CODE (x
);
3895 /* Recursively scan the operands of this expression. */
3898 const char * const fmt
= GET_RTX_FORMAT (code
);
3901 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3905 /* Tail recursive case: save a function call level. */
3911 mark_used_regs (pbi
, XEXP (x
, i
), cond
, insn
);
3913 else if (fmt
[i
] == 'E')
3916 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3917 mark_used_regs (pbi
, XVECEXP (x
, i
, j
), cond
, insn
);
3926 try_pre_increment_1 (struct propagate_block_info
*pbi
, rtx insn
)
3928 /* Find the next use of this reg. If in same basic block,
3929 make it do pre-increment or pre-decrement if appropriate. */
3930 rtx x
= single_set (insn
);
3931 HOST_WIDE_INT amount
= ((GET_CODE (SET_SRC (x
)) == PLUS
? 1 : -1)
3932 * INTVAL (XEXP (SET_SRC (x
), 1)));
3933 int regno
= REGNO (SET_DEST (x
));
3934 rtx y
= pbi
->reg_next_use
[regno
];
3936 && SET_DEST (x
) != stack_pointer_rtx
3937 && BLOCK_NUM (y
) == BLOCK_NUM (insn
)
3938 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3939 mode would be better. */
3940 && ! dead_or_set_p (y
, SET_DEST (x
))
3941 && try_pre_increment (y
, SET_DEST (x
), amount
))
3943 /* We have found a suitable auto-increment and already changed
3944 insn Y to do it. So flush this increment instruction. */
3945 propagate_block_delete_insn (insn
);
3947 /* Count a reference to this reg for the increment insn we are
3948 deleting. When a reg is incremented, spilling it is worse,
3949 so we want to make that less likely. */
3950 if (regno
>= FIRST_PSEUDO_REGISTER
)
3952 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
3953 REG_N_SETS (regno
)++;
3956 /* Flush any remembered memories depending on the value of
3957 the incremented register. */
3958 invalidate_mems_from_set (pbi
, SET_DEST (x
));
3965 /* Try to change INSN so that it does pre-increment or pre-decrement
3966 addressing on register REG in order to add AMOUNT to REG.
3967 AMOUNT is negative for pre-decrement.
3968 Returns 1 if the change could be made.
3969 This checks all about the validity of the result of modifying INSN. */
3972 try_pre_increment (rtx insn
, rtx reg
, HOST_WIDE_INT amount
)
3976 /* Nonzero if we can try to make a pre-increment or pre-decrement.
3977 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
3979 /* Nonzero if we can try to make a post-increment or post-decrement.
3980 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
3981 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
3982 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
3985 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
3988 /* From the sign of increment, see which possibilities are conceivable
3989 on this target machine. */
3990 if (HAVE_PRE_INCREMENT
&& amount
> 0)
3992 if (HAVE_POST_INCREMENT
&& amount
> 0)
3995 if (HAVE_PRE_DECREMENT
&& amount
< 0)
3997 if (HAVE_POST_DECREMENT
&& amount
< 0)
4000 if (! (pre_ok
|| post_ok
))
4003 /* It is not safe to add a side effect to a jump insn
4004 because if the incremented register is spilled and must be reloaded
4005 there would be no way to store the incremented value back in memory. */
4007 if (GET_CODE (insn
) == JUMP_INSN
)
4012 use
= find_use_as_address (PATTERN (insn
), reg
, 0);
4013 if (post_ok
&& (use
== 0 || use
== (rtx
) (size_t) 1))
4015 use
= find_use_as_address (PATTERN (insn
), reg
, -amount
);
4019 if (use
== 0 || use
== (rtx
) (size_t) 1)
4022 if (GET_MODE_SIZE (GET_MODE (use
)) != (amount
> 0 ? amount
: - amount
))
4025 /* See if this combination of instruction and addressing mode exists. */
4026 if (! validate_change (insn
, &XEXP (use
, 0),
4027 gen_rtx_fmt_e (amount
> 0
4028 ? (do_post
? POST_INC
: PRE_INC
)
4029 : (do_post
? POST_DEC
: PRE_DEC
),
4033 /* Record that this insn now has an implicit side effect on X. */
4034 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, reg
, REG_NOTES (insn
));
4038 #endif /* AUTO_INC_DEC */
4040 /* Find the place in the rtx X where REG is used as a memory address.
4041 Return the MEM rtx that so uses it.
4042 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4043 (plus REG (const_int PLUSCONST)).
4045 If such an address does not appear, return 0.
4046 If REG appears more than once, or is used other than in such an address,
4050 find_use_as_address (rtx x
, rtx reg
, HOST_WIDE_INT plusconst
)
4052 enum rtx_code code
= GET_CODE (x
);
4053 const char * const fmt
= GET_RTX_FORMAT (code
);
4058 if (code
== MEM
&& XEXP (x
, 0) == reg
&& plusconst
== 0)
4061 if (code
== MEM
&& GET_CODE (XEXP (x
, 0)) == PLUS
4062 && XEXP (XEXP (x
, 0), 0) == reg
4063 && GET_CODE (XEXP (XEXP (x
, 0), 1)) == CONST_INT
4064 && INTVAL (XEXP (XEXP (x
, 0), 1)) == plusconst
)
4067 if (code
== SIGN_EXTRACT
|| code
== ZERO_EXTRACT
)
4069 /* If REG occurs inside a MEM used in a bit-field reference,
4070 that is unacceptable. */
4071 if (find_use_as_address (XEXP (x
, 0), reg
, 0) != 0)
4072 return (rtx
) (size_t) 1;
4076 return (rtx
) (size_t) 1;
4078 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4082 tem
= find_use_as_address (XEXP (x
, i
), reg
, plusconst
);
4086 return (rtx
) (size_t) 1;
4088 else if (fmt
[i
] == 'E')
4091 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4093 tem
= find_use_as_address (XVECEXP (x
, i
, j
), reg
, plusconst
);
4097 return (rtx
) (size_t) 1;
4105 /* Write information about registers and basic blocks into FILE.
4106 This is part of making a debugging dump. */
4109 dump_regset (regset r
, FILE *outf
)
4114 fputs (" (nil)", outf
);
4118 EXECUTE_IF_SET_IN_REG_SET (r
, 0, i
,
4120 fprintf (outf
, " %d", i
);
4121 if (i
< FIRST_PSEUDO_REGISTER
)
4122 fprintf (outf
, " [%s]",
4127 /* Print a human-readable representation of R on the standard error
4128 stream. This function is designed to be used from within the
4132 debug_regset (regset r
)
4134 dump_regset (r
, stderr
);
4135 putc ('\n', stderr
);
4138 /* Recompute register set/reference counts immediately prior to register
4141 This avoids problems with set/reference counts changing to/from values
4142 which have special meanings to the register allocators.
4144 Additionally, the reference counts are the primary component used by the
4145 register allocators to prioritize pseudos for allocation to hard regs.
4146 More accurate reference counts generally lead to better register allocation.
4148 F is the first insn to be scanned.
4150 LOOP_STEP denotes how much loop_depth should be incremented per
4151 loop nesting level in order to increase the ref count more for
4152 references in a loop.
4154 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4155 possibly other information which is used by the register allocators. */
4158 recompute_reg_usage (rtx f ATTRIBUTE_UNUSED
, int loop_step ATTRIBUTE_UNUSED
)
4160 allocate_reg_life_data ();
4161 update_life_info (NULL
, UPDATE_LIFE_LOCAL
, PROP_REG_INFO
);
4164 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4165 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4166 of the number of registers that died. */
4169 count_or_remove_death_notes (sbitmap blocks
, int kill
)
4176 /* This used to be a loop over all the blocks with a membership test
4177 inside the loop. That can be amazingly expensive on a large CFG
4178 when only a small number of bits are set in BLOCKs (for example,
4179 the calls from the scheduler typically have very few bits set).
4181 For extra credit, someone should convert BLOCKS to a bitmap rather
4185 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4187 count
+= count_or_remove_death_notes_bb (BASIC_BLOCK (i
), kill
);
4194 count
+= count_or_remove_death_notes_bb (bb
, kill
);
4201 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from basic
4202 block BB. Returns a count of the number of registers that died. */
4205 count_or_remove_death_notes_bb (basic_block bb
, int kill
)
4210 for (insn
= bb
->head
;; insn
= NEXT_INSN (insn
))
4214 rtx
*pprev
= ®_NOTES (insn
);
4219 switch (REG_NOTE_KIND (link
))
4222 if (GET_CODE (XEXP (link
, 0)) == REG
)
4224 rtx reg
= XEXP (link
, 0);
4227 if (REGNO (reg
) >= FIRST_PSEUDO_REGISTER
)
4230 n
= HARD_REGNO_NREGS (REGNO (reg
), GET_MODE (reg
));
4239 rtx next
= XEXP (link
, 1);
4240 free_EXPR_LIST_node (link
);
4241 *pprev
= link
= next
;
4247 pprev
= &XEXP (link
, 1);
4254 if (insn
== bb
->end
)
4261 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4262 if blocks is NULL. */
4265 clear_log_links (sbitmap blocks
)
4272 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
4274 free_INSN_LIST_list (&LOG_LINKS (insn
));
4277 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4279 basic_block bb
= BASIC_BLOCK (i
);
4281 for (insn
= bb
->head
; insn
!= NEXT_INSN (bb
->end
);
4282 insn
= NEXT_INSN (insn
))
4284 free_INSN_LIST_list (&LOG_LINKS (insn
));
4288 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4289 correspond to the hard registers, if any, set in that map. This
4290 could be done far more efficiently by having all sorts of special-cases
4291 with moving single words, but probably isn't worth the trouble. */
4294 reg_set_to_hard_reg_set (HARD_REG_SET
*to
, bitmap from
)
4298 EXECUTE_IF_SET_IN_BITMAP
4301 if (i
>= FIRST_PSEUDO_REGISTER
)
4303 SET_HARD_REG_BIT (*to
, i
);