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, 2004 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 #ifndef HAVE_epilogue
145 #define HAVE_epilogue 0
147 #ifndef HAVE_prologue
148 #define HAVE_prologue 0
150 #ifndef HAVE_sibcall_epilogue
151 #define HAVE_sibcall_epilogue 0
154 #ifndef EPILOGUE_USES
155 #define EPILOGUE_USES(REGNO) 0
158 #define EH_USES(REGNO) 0
161 #ifdef HAVE_conditional_execution
162 #ifndef REVERSE_CONDEXEC_PREDICATES_P
163 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) \
164 (GET_CODE ((x)) == reversed_comparison_code ((y), NULL))
168 /* Nonzero if the second flow pass has completed. */
171 /* Maximum register number used in this function, plus one. */
175 /* Indexed by n, giving various register information */
177 varray_type reg_n_info
;
179 /* Size of a regset for the current function,
180 in (1) bytes and (2) elements. */
185 /* Regset of regs live when calls to `setjmp'-like functions happen. */
186 /* ??? Does this exist only for the setjmp-clobbered warning message? */
188 regset regs_live_at_setjmp
;
190 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
191 that have to go in the same hard reg.
192 The first two regs in the list are a pair, and the next two
193 are another pair, etc. */
196 /* Set of registers that may be eliminable. These are handled specially
197 in updating regs_ever_live. */
199 static HARD_REG_SET elim_reg_set
;
201 /* Holds information for tracking conditional register life information. */
202 struct reg_cond_life_info
204 /* A boolean expression of conditions under which a register is dead. */
206 /* Conditions under which a register is dead at the basic block end. */
209 /* A boolean expression of conditions under which a register has been
213 /* ??? Could store mask of bytes that are dead, so that we could finally
214 track lifetimes of multi-word registers accessed via subregs. */
217 /* For use in communicating between propagate_block and its subroutines.
218 Holds all information needed to compute life and def-use information. */
220 struct propagate_block_info
222 /* The basic block we're considering. */
225 /* Bit N is set if register N is conditionally or unconditionally live. */
228 /* Bit N is set if register N is set this insn. */
231 /* Element N is the next insn that uses (hard or pseudo) register N
232 within the current basic block; or zero, if there is no such insn. */
235 /* Contains a list of all the MEMs we are tracking for dead store
239 /* If non-null, record the set of registers set unconditionally in the
243 /* If non-null, record the set of registers set conditionally in the
245 regset cond_local_set
;
247 #ifdef HAVE_conditional_execution
248 /* Indexed by register number, holds a reg_cond_life_info for each
249 register that is not unconditionally live or dead. */
250 splay_tree reg_cond_dead
;
252 /* Bit N is set if register N is in an expression in reg_cond_dead. */
256 /* The length of mem_set_list. */
257 int mem_set_list_len
;
259 /* Nonzero if the value of CC0 is live. */
262 /* Flags controlling the set of information propagate_block collects. */
264 /* Index of instruction being processed. */
268 /* Number of dead insns removed. */
271 /* When PROP_REG_INFO set, array contains pbi->insn_num of instruction
272 where given register died. When the register is marked alive, we use the
273 information to compute amount of instructions life range cross.
274 (remember, we are walking backward). This can be computed as current
275 pbi->insn_num - reg_deaths[regno].
276 At the end of processing each basic block, the remaining live registers
277 are inspected and liferanges are increased same way so liverange of global
278 registers are computed correctly.
280 The array is maintained clear for dead registers, so it can be safely reused
281 for next basic block without expensive memset of the whole array after
282 reseting pbi->insn_num to 0. */
284 static int *reg_deaths
;
286 /* Maximum length of pbi->mem_set_list before we start dropping
287 new elements on the floor. */
288 #define MAX_MEM_SET_LIST_LEN 100
290 /* Forward declarations */
291 static int verify_wide_reg_1 (rtx
*, void *);
292 static void verify_wide_reg (int, basic_block
);
293 static void verify_local_live_at_start (regset
, basic_block
);
294 static void notice_stack_pointer_modification_1 (rtx
, rtx
, void *);
295 static void notice_stack_pointer_modification (void);
296 static void mark_reg (rtx
, void *);
297 static void mark_regs_live_at_end (regset
);
298 static void calculate_global_regs_live (sbitmap
, sbitmap
, int);
299 static void propagate_block_delete_insn (rtx
);
300 static rtx
propagate_block_delete_libcall (rtx
, rtx
);
301 static int insn_dead_p (struct propagate_block_info
*, rtx
, int, rtx
);
302 static int libcall_dead_p (struct propagate_block_info
*, rtx
, rtx
);
303 static void mark_set_regs (struct propagate_block_info
*, rtx
, rtx
);
304 static void mark_set_1 (struct propagate_block_info
*, enum rtx_code
, rtx
,
306 static int find_regno_partial (rtx
*, void *);
308 #ifdef HAVE_conditional_execution
309 static int mark_regno_cond_dead (struct propagate_block_info
*, int, rtx
);
310 static void free_reg_cond_life_info (splay_tree_value
);
311 static int flush_reg_cond_reg_1 (splay_tree_node
, void *);
312 static void flush_reg_cond_reg (struct propagate_block_info
*, int);
313 static rtx
elim_reg_cond (rtx
, unsigned int);
314 static rtx
ior_reg_cond (rtx
, rtx
, int);
315 static rtx
not_reg_cond (rtx
);
316 static rtx
and_reg_cond (rtx
, rtx
, int);
319 static void attempt_auto_inc (struct propagate_block_info
*, rtx
, rtx
, rtx
,
321 static void find_auto_inc (struct propagate_block_info
*, rtx
, rtx
);
322 static int try_pre_increment_1 (struct propagate_block_info
*, rtx
);
323 static int try_pre_increment (rtx
, rtx
, HOST_WIDE_INT
);
325 static void mark_used_reg (struct propagate_block_info
*, rtx
, rtx
, rtx
);
326 static void mark_used_regs (struct propagate_block_info
*, rtx
, rtx
, rtx
);
327 void debug_flow_info (void);
328 static void add_to_mem_set_list (struct propagate_block_info
*, rtx
);
329 static int invalidate_mems_from_autoinc (rtx
*, void *);
330 static void invalidate_mems_from_set (struct propagate_block_info
*, rtx
);
331 static void clear_log_links (sbitmap
);
332 static int count_or_remove_death_notes_bb (basic_block
, int);
334 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
335 note associated with the BLOCK. */
338 first_insn_after_basic_block_note (basic_block block
)
342 /* Get the first instruction in the block. */
343 insn
= BB_HEAD (block
);
345 if (insn
== NULL_RTX
)
348 insn
= NEXT_INSN (insn
);
349 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn
));
351 return NEXT_INSN (insn
);
354 /* Perform data flow analysis for the whole control flow graph.
355 FLAGS is a set of PROP_* flags to be used in accumulating flow info. */
358 life_analysis (FILE *file
, int flags
)
360 #ifdef ELIMINABLE_REGS
362 static const struct {const int from
, to
; } eliminables
[] = ELIMINABLE_REGS
;
365 /* Record which registers will be eliminated. We use this in
368 CLEAR_HARD_REG_SET (elim_reg_set
);
370 #ifdef ELIMINABLE_REGS
371 for (i
= 0; i
< (int) ARRAY_SIZE (eliminables
); i
++)
372 SET_HARD_REG_BIT (elim_reg_set
, eliminables
[i
].from
);
374 SET_HARD_REG_BIT (elim_reg_set
, FRAME_POINTER_REGNUM
);
378 #ifdef CANNOT_CHANGE_MODE_CLASS
379 if (flags
& PROP_REG_INFO
)
380 init_subregs_of_mode ();
384 flags
&= ~(PROP_LOG_LINKS
| PROP_AUTOINC
| PROP_ALLOW_CFG_CHANGES
);
386 /* The post-reload life analysis have (on a global basis) the same
387 registers live as was computed by reload itself. elimination
388 Otherwise offsets and such may be incorrect.
390 Reload will make some registers as live even though they do not
393 We don't want to create new auto-incs after reload, since they
394 are unlikely to be useful and can cause problems with shared
396 if (reload_completed
)
397 flags
&= ~(PROP_REG_INFO
| PROP_AUTOINC
);
399 /* We want alias analysis information for local dead store elimination. */
400 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
401 init_alias_analysis ();
403 /* Always remove no-op moves. Do this before other processing so
404 that we don't have to keep re-scanning them. */
405 delete_noop_moves ();
407 /* Some targets can emit simpler epilogues if they know that sp was
408 not ever modified during the function. After reload, of course,
409 we've already emitted the epilogue so there's no sense searching. */
410 if (! reload_completed
)
411 notice_stack_pointer_modification ();
413 /* Allocate and zero out data structures that will record the
414 data from lifetime analysis. */
415 allocate_reg_life_data ();
416 allocate_bb_life_data ();
418 /* Find the set of registers live on function exit. */
419 mark_regs_live_at_end (EXIT_BLOCK_PTR
->global_live_at_start
);
421 /* "Update" life info from zero. It'd be nice to begin the
422 relaxation with just the exit and noreturn blocks, but that set
423 is not immediately handy. */
425 if (flags
& PROP_REG_INFO
)
427 memset (regs_ever_live
, 0, sizeof (regs_ever_live
));
428 memset (regs_asm_clobbered
, 0, sizeof (regs_asm_clobbered
));
430 update_life_info (NULL
, UPDATE_LIFE_GLOBAL
, flags
);
438 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
439 end_alias_analysis ();
442 dump_flow_info (file
);
444 /* Removing dead insns should have made jumptables really dead. */
445 delete_dead_jumptables ();
448 /* A subroutine of verify_wide_reg, called through for_each_rtx.
449 Search for REGNO. If found, return 2 if it is not wider than
453 verify_wide_reg_1 (rtx
*px
, void *pregno
)
456 unsigned int regno
= *(int *) pregno
;
458 if (REG_P (x
) && REGNO (x
) == regno
)
460 if (GET_MODE_BITSIZE (GET_MODE (x
)) <= BITS_PER_WORD
)
467 /* A subroutine of verify_local_live_at_start. Search through insns
468 of BB looking for register REGNO. */
471 verify_wide_reg (int regno
, basic_block bb
)
473 rtx head
= BB_HEAD (bb
), end
= BB_END (bb
);
479 int r
= for_each_rtx (&PATTERN (head
), verify_wide_reg_1
, ®no
);
487 head
= NEXT_INSN (head
);
491 fprintf (dump_file
, "Register %d died unexpectedly.\n", regno
);
492 dump_bb (bb
, dump_file
, 0);
494 fatal_error ("internal consistency failure");
497 /* A subroutine of update_life_info. Verify that there are no untoward
498 changes in live_at_start during a local update. */
501 verify_local_live_at_start (regset new_live_at_start
, basic_block bb
)
503 if (reload_completed
)
505 /* After reload, there are no pseudos, nor subregs of multi-word
506 registers. The regsets should exactly match. */
507 if (! REG_SET_EQUAL_P (new_live_at_start
, bb
->global_live_at_start
))
512 "live_at_start mismatch in bb %d, aborting\nNew:\n",
514 debug_bitmap_file (dump_file
, new_live_at_start
);
515 fputs ("Old:\n", dump_file
);
516 dump_bb (bb
, dump_file
, 0);
518 fatal_error ("internal consistency failure");
524 reg_set_iterator rsi
;
526 /* Find the set of changed registers. */
527 XOR_REG_SET (new_live_at_start
, bb
->global_live_at_start
);
529 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start
, 0, i
, rsi
)
531 /* No registers should die. */
532 if (REGNO_REG_SET_P (bb
->global_live_at_start
, i
))
537 "Register %d died unexpectedly.\n", i
);
538 dump_bb (bb
, dump_file
, 0);
540 fatal_error ("internal consistency failure");
542 /* Verify that the now-live register is wider than word_mode. */
543 verify_wide_reg (i
, bb
);
548 /* Updates life information starting with the basic blocks set in BLOCKS.
549 If BLOCKS is null, consider it to be the universal set.
551 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholing,
552 we are only expecting local modifications to basic blocks. If we find
553 extra registers live at the beginning of a block, then we either killed
554 useful data, or we have a broken split that wants data not provided.
555 If we find registers removed from live_at_start, that means we have
556 a broken peephole that is killing a register it shouldn't.
558 ??? This is not true in one situation -- when a pre-reload splitter
559 generates subregs of a multi-word pseudo, current life analysis will
560 lose the kill. So we _can_ have a pseudo go live. How irritating.
562 It is also not true when a peephole decides that it doesn't need one
563 or more of the inputs.
565 Including PROP_REG_INFO does not properly refresh regs_ever_live
566 unless the caller resets it to zero. */
569 update_life_info (sbitmap blocks
, enum update_life_extent extent
, int prop_flags
)
572 regset_head tmp_head
;
574 int stabilized_prop_flags
= prop_flags
;
577 tmp
= INITIALIZE_REG_SET (tmp_head
);
580 if ((prop_flags
& PROP_REG_INFO
) && !reg_deaths
)
581 reg_deaths
= xcalloc (sizeof (*reg_deaths
), max_regno
);
583 timevar_push ((extent
== UPDATE_LIFE_LOCAL
|| blocks
)
584 ? TV_LIFE_UPDATE
: TV_LIFE
);
586 /* Changes to the CFG are only allowed when
587 doing a global update for the entire CFG. */
588 gcc_assert (!(prop_flags
& PROP_ALLOW_CFG_CHANGES
)
589 || (extent
!= UPDATE_LIFE_LOCAL
&& !blocks
));
591 /* For a global update, we go through the relaxation process again. */
592 if (extent
!= UPDATE_LIFE_LOCAL
)
598 calculate_global_regs_live (blocks
, blocks
,
599 prop_flags
& (PROP_SCAN_DEAD_CODE
600 | PROP_SCAN_DEAD_STORES
601 | PROP_ALLOW_CFG_CHANGES
));
603 if ((prop_flags
& (PROP_KILL_DEAD_CODE
| PROP_ALLOW_CFG_CHANGES
))
604 != (PROP_KILL_DEAD_CODE
| PROP_ALLOW_CFG_CHANGES
))
607 /* Removing dead code may allow the CFG to be simplified which
608 in turn may allow for further dead code detection / removal. */
609 FOR_EACH_BB_REVERSE (bb
)
611 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
612 changed
|= propagate_block (bb
, tmp
, NULL
, NULL
,
613 prop_flags
& (PROP_SCAN_DEAD_CODE
614 | PROP_SCAN_DEAD_STORES
615 | PROP_KILL_DEAD_CODE
));
618 /* Don't pass PROP_SCAN_DEAD_CODE or PROP_KILL_DEAD_CODE to
619 subsequent propagate_block calls, since removing or acting as
620 removing dead code can affect global register liveness, which
621 is supposed to be finalized for this call after this loop. */
622 stabilized_prop_flags
623 &= ~(PROP_SCAN_DEAD_CODE
| PROP_SCAN_DEAD_STORES
624 | PROP_KILL_DEAD_CODE
);
629 /* We repeat regardless of what cleanup_cfg says. If there were
630 instructions deleted above, that might have been only a
631 partial improvement (see MAX_MEM_SET_LIST_LEN usage).
632 Further improvement may be possible. */
633 cleanup_cfg (CLEANUP_EXPENSIVE
);
635 /* Zap the life information from the last round. If we don't
636 do this, we can wind up with registers that no longer appear
637 in the code being marked live at entry. */
640 CLEAR_REG_SET (bb
->global_live_at_start
);
641 CLEAR_REG_SET (bb
->global_live_at_end
);
645 /* If asked, remove notes from the blocks we'll update. */
646 if (extent
== UPDATE_LIFE_GLOBAL_RM_NOTES
)
647 count_or_remove_death_notes (blocks
, 1);
650 /* Clear log links in case we are asked to (re)compute them. */
651 if (prop_flags
& PROP_LOG_LINKS
)
652 clear_log_links (blocks
);
656 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
658 bb
= BASIC_BLOCK (i
);
660 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
661 propagate_block (bb
, tmp
, NULL
, NULL
, stabilized_prop_flags
);
663 if (extent
== UPDATE_LIFE_LOCAL
)
664 verify_local_live_at_start (tmp
, bb
);
669 FOR_EACH_BB_REVERSE (bb
)
671 COPY_REG_SET (tmp
, bb
->global_live_at_end
);
673 propagate_block (bb
, tmp
, NULL
, NULL
, stabilized_prop_flags
);
675 if (extent
== UPDATE_LIFE_LOCAL
)
676 verify_local_live_at_start (tmp
, bb
);
682 if (prop_flags
& PROP_REG_INFO
)
684 reg_set_iterator rsi
;
686 /* The only pseudos that are live at the beginning of the function
687 are those that were not set anywhere in the function. local-alloc
688 doesn't know how to handle these correctly, so mark them as not
689 local to any one basic block. */
690 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR
->global_live_at_end
,
691 FIRST_PSEUDO_REGISTER
, i
, rsi
)
692 REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
;
694 /* We have a problem with any pseudoreg that lives across the setjmp.
695 ANSI says that if a user variable does not change in value between
696 the setjmp and the longjmp, then the longjmp preserves it. This
697 includes longjmp from a place where the pseudo appears dead.
698 (In principle, the value still exists if it is in scope.)
699 If the pseudo goes in a hard reg, some other value may occupy
700 that hard reg where this pseudo is dead, thus clobbering the pseudo.
701 Conclusion: such a pseudo must not go in a hard reg. */
702 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp
,
703 FIRST_PSEUDO_REGISTER
, i
, rsi
)
705 if (regno_reg_rtx
[i
] != 0)
707 REG_LIVE_LENGTH (i
) = -1;
708 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
717 timevar_pop ((extent
== UPDATE_LIFE_LOCAL
|| blocks
)
718 ? TV_LIFE_UPDATE
: TV_LIFE
);
719 if (ndead
&& dump_file
)
720 fprintf (dump_file
, "deleted %i dead insns\n", ndead
);
724 /* Update life information in all blocks where BB_DIRTY is set. */
727 update_life_info_in_dirty_blocks (enum update_life_extent extent
, int prop_flags
)
729 sbitmap update_life_blocks
= sbitmap_alloc (last_basic_block
);
734 sbitmap_zero (update_life_blocks
);
737 if (extent
== UPDATE_LIFE_LOCAL
)
739 if (bb
->flags
& BB_DIRTY
)
741 SET_BIT (update_life_blocks
, bb
->index
);
747 /* ??? Bootstrap with -march=pentium4 fails to terminate
748 with only a partial life update. */
749 SET_BIT (update_life_blocks
, bb
->index
);
750 if (bb
->flags
& BB_DIRTY
)
756 retval
= update_life_info (update_life_blocks
, extent
, prop_flags
);
758 sbitmap_free (update_life_blocks
);
762 /* Free the variables allocated by find_basic_blocks. */
765 free_basic_block_vars (void)
767 if (basic_block_info
)
770 basic_block_info
= NULL
;
773 last_basic_block
= 0;
775 ENTRY_BLOCK_PTR
->aux
= NULL
;
776 ENTRY_BLOCK_PTR
->global_live_at_end
= NULL
;
777 EXIT_BLOCK_PTR
->aux
= NULL
;
778 EXIT_BLOCK_PTR
->global_live_at_start
= NULL
;
781 /* Delete any insns that copy a register to itself. */
784 delete_noop_moves (void)
792 for (insn
= BB_HEAD (bb
); insn
!= NEXT_INSN (BB_END (bb
)); insn
= next
)
794 next
= NEXT_INSN (insn
);
795 if (INSN_P (insn
) && noop_move_p (insn
))
799 /* If we're about to remove the first insn of a libcall
800 then move the libcall note to the next real insn and
801 update the retval note. */
802 if ((note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
803 && XEXP (note
, 0) != insn
)
805 rtx new_libcall_insn
= next_real_insn (insn
);
806 rtx retval_note
= find_reg_note (XEXP (note
, 0),
807 REG_RETVAL
, NULL_RTX
);
808 REG_NOTES (new_libcall_insn
)
809 = gen_rtx_INSN_LIST (REG_LIBCALL
, XEXP (note
, 0),
810 REG_NOTES (new_libcall_insn
));
811 XEXP (retval_note
, 0) = new_libcall_insn
;
814 delete_insn_and_edges (insn
);
819 if (nnoops
&& dump_file
)
820 fprintf (dump_file
, "deleted %i noop moves", nnoops
);
824 /* Delete any jump tables never referenced. We can't delete them at the
825 time of removing tablejump insn as they are referenced by the preceding
826 insns computing the destination, so we delay deleting and garbagecollect
827 them once life information is computed. */
829 delete_dead_jumptables (void)
832 for (insn
= get_insns (); insn
; insn
= next
)
834 next
= NEXT_INSN (insn
);
836 && LABEL_NUSES (insn
) == LABEL_PRESERVE_P (insn
)
838 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
839 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
842 fprintf (dump_file
, "Dead jumptable %i removed\n", INSN_UID (insn
));
843 delete_insn (NEXT_INSN (insn
));
845 next
= NEXT_INSN (next
);
850 /* Determine if the stack pointer is constant over the life of the function.
851 Only useful before prologues have been emitted. */
854 notice_stack_pointer_modification_1 (rtx x
, rtx pat ATTRIBUTE_UNUSED
,
855 void *data ATTRIBUTE_UNUSED
)
857 if (x
== stack_pointer_rtx
858 /* The stack pointer is only modified indirectly as the result
859 of a push until later in flow. See the comments in rtl.texi
860 regarding Embedded Side-Effects on Addresses. */
862 && GET_RTX_CLASS (GET_CODE (XEXP (x
, 0))) == RTX_AUTOINC
863 && XEXP (XEXP (x
, 0), 0) == stack_pointer_rtx
))
864 current_function_sp_is_unchanging
= 0;
868 notice_stack_pointer_modification (void)
873 /* Assume that the stack pointer is unchanging if alloca hasn't
875 current_function_sp_is_unchanging
= !current_function_calls_alloca
;
876 if (! current_function_sp_is_unchanging
)
880 FOR_BB_INSNS (bb
, insn
)
884 /* Check if insn modifies the stack pointer. */
885 note_stores (PATTERN (insn
),
886 notice_stack_pointer_modification_1
,
888 if (! current_function_sp_is_unchanging
)
894 /* Mark a register in SET. Hard registers in large modes get all
895 of their component registers set as well. */
898 mark_reg (rtx reg
, void *xset
)
900 regset set
= (regset
) xset
;
901 int regno
= REGNO (reg
);
903 gcc_assert (GET_MODE (reg
) != BLKmode
);
905 SET_REGNO_REG_SET (set
, regno
);
906 if (regno
< FIRST_PSEUDO_REGISTER
)
908 int n
= hard_regno_nregs
[regno
][GET_MODE (reg
)];
910 SET_REGNO_REG_SET (set
, regno
+ n
);
914 /* Mark those regs which are needed at the end of the function as live
915 at the end of the last basic block. */
918 mark_regs_live_at_end (regset set
)
922 /* If exiting needs the right stack value, consider the stack pointer
923 live at the end of the function. */
924 if ((HAVE_epilogue
&& epilogue_completed
)
925 || ! EXIT_IGNORE_STACK
926 || (! FRAME_POINTER_REQUIRED
927 && ! current_function_calls_alloca
928 && flag_omit_frame_pointer
)
929 || current_function_sp_is_unchanging
)
931 SET_REGNO_REG_SET (set
, STACK_POINTER_REGNUM
);
934 /* Mark the frame pointer if needed at the end of the function. If
935 we end up eliminating it, it will be removed from the live list
936 of each basic block by reload. */
938 if (! reload_completed
|| frame_pointer_needed
)
940 SET_REGNO_REG_SET (set
, FRAME_POINTER_REGNUM
);
941 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
942 /* If they are different, also mark the hard frame pointer as live. */
943 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM
))
944 SET_REGNO_REG_SET (set
, HARD_FRAME_POINTER_REGNUM
);
948 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
949 /* Many architectures have a GP register even without flag_pic.
950 Assume the pic register is not in use, or will be handled by
951 other means, if it is not fixed. */
952 if ((unsigned) PIC_OFFSET_TABLE_REGNUM
!= INVALID_REGNUM
953 && fixed_regs
[PIC_OFFSET_TABLE_REGNUM
])
954 SET_REGNO_REG_SET (set
, PIC_OFFSET_TABLE_REGNUM
);
957 /* Mark all global registers, and all registers used by the epilogue
958 as being live at the end of the function since they may be
959 referenced by our caller. */
960 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
961 if (global_regs
[i
] || EPILOGUE_USES (i
))
962 SET_REGNO_REG_SET (set
, i
);
964 if (HAVE_epilogue
&& epilogue_completed
)
966 /* Mark all call-saved registers that we actually used. */
967 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
968 if (regs_ever_live
[i
] && ! LOCAL_REGNO (i
)
969 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
))
970 SET_REGNO_REG_SET (set
, i
);
973 #ifdef EH_RETURN_DATA_REGNO
974 /* Mark the registers that will contain data for the handler. */
975 if (reload_completed
&& current_function_calls_eh_return
)
978 unsigned regno
= EH_RETURN_DATA_REGNO(i
);
979 if (regno
== INVALID_REGNUM
)
981 SET_REGNO_REG_SET (set
, regno
);
984 #ifdef EH_RETURN_STACKADJ_RTX
985 if ((! HAVE_epilogue
|| ! epilogue_completed
)
986 && current_function_calls_eh_return
)
988 rtx tmp
= EH_RETURN_STACKADJ_RTX
;
989 if (tmp
&& REG_P (tmp
))
993 #ifdef EH_RETURN_HANDLER_RTX
994 if ((! HAVE_epilogue
|| ! epilogue_completed
)
995 && current_function_calls_eh_return
)
997 rtx tmp
= EH_RETURN_HANDLER_RTX
;
998 if (tmp
&& REG_P (tmp
))
1003 /* Mark function return value. */
1004 diddle_return_value (mark_reg
, set
);
1007 /* Propagate global life info around the graph of basic blocks. Begin
1008 considering blocks with their corresponding bit set in BLOCKS_IN.
1009 If BLOCKS_IN is null, consider it the universal set.
1011 BLOCKS_OUT is set for every block that was changed. */
1014 calculate_global_regs_live (sbitmap blocks_in
, sbitmap blocks_out
, int flags
)
1016 basic_block
*queue
, *qhead
, *qtail
, *qend
, bb
;
1017 regset tmp
, new_live_at_end
, invalidated_by_call
;
1018 regset_head tmp_head
, invalidated_by_call_head
;
1019 regset_head new_live_at_end_head
;
1022 /* Some passes used to forget clear aux field of basic block causing
1023 sick behavior here. */
1024 #ifdef ENABLE_CHECKING
1025 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
1026 gcc_assert (!bb
->aux
);
1029 tmp
= INITIALIZE_REG_SET (tmp_head
);
1030 new_live_at_end
= INITIALIZE_REG_SET (new_live_at_end_head
);
1031 invalidated_by_call
= INITIALIZE_REG_SET (invalidated_by_call_head
);
1033 /* Inconveniently, this is only readily available in hard reg set form. */
1034 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; ++i
)
1035 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
))
1036 SET_REGNO_REG_SET (invalidated_by_call
, i
);
1038 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1039 because the `head == tail' style test for an empty queue doesn't
1040 work with a full queue. */
1041 queue
= xmalloc ((n_basic_blocks
+ 2) * sizeof (*queue
));
1043 qhead
= qend
= queue
+ n_basic_blocks
+ 2;
1045 /* Queue the blocks set in the initial mask. Do this in reverse block
1046 number order so that we are more likely for the first round to do
1047 useful work. We use AUX non-null to flag that the block is queued. */
1051 if (TEST_BIT (blocks_in
, bb
->index
))
1066 /* We clean aux when we remove the initially-enqueued bbs, but we
1067 don't enqueue ENTRY and EXIT initially, so clean them upfront and
1069 ENTRY_BLOCK_PTR
->aux
= EXIT_BLOCK_PTR
->aux
= NULL
;
1072 sbitmap_zero (blocks_out
);
1074 /* We work through the queue until there are no more blocks. What
1075 is live at the end of this block is precisely the union of what
1076 is live at the beginning of all its successors. So, we set its
1077 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1078 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1079 this block by walking through the instructions in this block in
1080 reverse order and updating as we go. If that changed
1081 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1082 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1084 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1085 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1086 must either be live at the end of the block, or used within the
1087 block. In the latter case, it will certainly never disappear
1088 from GLOBAL_LIVE_AT_START. In the former case, the register
1089 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1090 for one of the successor blocks. By induction, that cannot
1092 while (qhead
!= qtail
)
1094 int rescan
, changed
;
1104 /* Begin by propagating live_at_start from the successor blocks. */
1105 CLEAR_REG_SET (new_live_at_end
);
1107 if (EDGE_COUNT (bb
->succs
) > 0)
1108 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
1110 basic_block sb
= e
->dest
;
1112 /* Call-clobbered registers die across exception and
1114 /* ??? Abnormal call edges ignored for the moment, as this gets
1115 confused by sibling call edges, which crashes reg-stack. */
1116 if (e
->flags
& EDGE_EH
)
1117 bitmap_ior_and_compl_into (new_live_at_end
,
1118 sb
->global_live_at_start
,
1119 invalidated_by_call
);
1121 IOR_REG_SET (new_live_at_end
, sb
->global_live_at_start
);
1123 /* If a target saves one register in another (instead of on
1124 the stack) the save register will need to be live for EH. */
1125 if (e
->flags
& EDGE_EH
)
1126 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1128 SET_REGNO_REG_SET (new_live_at_end
, i
);
1132 /* This might be a noreturn function that throws. And
1133 even if it isn't, getting the unwind info right helps
1135 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1137 SET_REGNO_REG_SET (new_live_at_end
, i
);
1140 /* The all-important stack pointer must always be live. */
1141 SET_REGNO_REG_SET (new_live_at_end
, STACK_POINTER_REGNUM
);
1143 /* Before reload, there are a few registers that must be forced
1144 live everywhere -- which might not already be the case for
1145 blocks within infinite loops. */
1146 if (! reload_completed
)
1148 /* Any reference to any pseudo before reload is a potential
1149 reference of the frame pointer. */
1150 SET_REGNO_REG_SET (new_live_at_end
, FRAME_POINTER_REGNUM
);
1152 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1153 /* Pseudos with argument area equivalences may require
1154 reloading via the argument pointer. */
1155 if (fixed_regs
[ARG_POINTER_REGNUM
])
1156 SET_REGNO_REG_SET (new_live_at_end
, ARG_POINTER_REGNUM
);
1159 /* Any constant, or pseudo with constant equivalences, may
1160 require reloading from memory using the pic register. */
1161 if ((unsigned) PIC_OFFSET_TABLE_REGNUM
!= INVALID_REGNUM
1162 && fixed_regs
[PIC_OFFSET_TABLE_REGNUM
])
1163 SET_REGNO_REG_SET (new_live_at_end
, PIC_OFFSET_TABLE_REGNUM
);
1166 if (bb
== ENTRY_BLOCK_PTR
)
1168 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1172 /* On our first pass through this block, we'll go ahead and continue.
1173 Recognize first pass by local_set NULL. On subsequent passes, we
1174 get to skip out early if live_at_end wouldn't have changed. */
1176 if (bb
->local_set
== NULL
)
1178 bb
->local_set
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1179 bb
->cond_local_set
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1184 /* If any bits were removed from live_at_end, we'll have to
1185 rescan the block. This wouldn't be necessary if we had
1186 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1187 local_live is really dependent on live_at_end. */
1188 CLEAR_REG_SET (tmp
);
1189 rescan
= bitmap_and_compl (tmp
, bb
->global_live_at_end
,
1194 /* If any of the registers in the new live_at_end set are
1195 conditionally set in this basic block, we must rescan.
1196 This is because conditional lifetimes at the end of the
1197 block do not just take the live_at_end set into account,
1198 but also the liveness at the start of each successor
1199 block. We can miss changes in those sets if we only
1200 compare the new live_at_end against the previous one. */
1201 CLEAR_REG_SET (tmp
);
1202 rescan
= bitmap_and (tmp
, new_live_at_end
,
1203 bb
->cond_local_set
);
1208 /* Find the set of changed bits. Take this opportunity
1209 to notice that this set is empty and early out. */
1210 CLEAR_REG_SET (tmp
);
1211 changed
= bitmap_xor (tmp
, bb
->global_live_at_end
,
1216 /* If any of the changed bits overlap with local_set,
1217 we'll have to rescan the block. Detect overlap by
1218 the AND with ~local_set turning off bits. */
1219 rescan
= bitmap_and_compl_into (tmp
, bb
->local_set
);
1223 /* Let our caller know that BB changed enough to require its
1224 death notes updated. */
1226 SET_BIT (blocks_out
, bb
->index
);
1230 /* Add to live_at_start the set of all registers in
1231 new_live_at_end that aren't in the old live_at_end. */
1233 changed
= bitmap_ior_and_compl_into (bb
->global_live_at_start
,
1235 bb
->global_live_at_end
);
1236 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1242 COPY_REG_SET (bb
->global_live_at_end
, new_live_at_end
);
1244 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1245 into live_at_start. */
1246 propagate_block (bb
, new_live_at_end
, bb
->local_set
,
1247 bb
->cond_local_set
, flags
);
1249 /* If live_at start didn't change, no need to go farther. */
1250 if (REG_SET_EQUAL_P (bb
->global_live_at_start
, new_live_at_end
))
1253 COPY_REG_SET (bb
->global_live_at_start
, new_live_at_end
);
1256 /* Queue all predecessors of BB so that we may re-examine
1257 their live_at_end. */
1258 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
1260 basic_block pb
= e
->src
;
1261 if (pb
->aux
== NULL
)
1272 FREE_REG_SET (new_live_at_end
);
1273 FREE_REG_SET (invalidated_by_call
);
1277 EXECUTE_IF_SET_IN_SBITMAP (blocks_out
, 0, i
,
1279 basic_block bb
= BASIC_BLOCK (i
);
1280 FREE_REG_SET (bb
->local_set
);
1281 FREE_REG_SET (bb
->cond_local_set
);
1288 FREE_REG_SET (bb
->local_set
);
1289 FREE_REG_SET (bb
->cond_local_set
);
1297 /* This structure is used to pass parameters to and from the
1298 the function find_regno_partial(). It is used to pass in the
1299 register number we are looking, as well as to return any rtx
1303 unsigned regno_to_find
;
1305 } find_regno_partial_param
;
1308 /* Find the rtx for the reg numbers specified in 'data' if it is
1309 part of an expression which only uses part of the register. Return
1310 it in the structure passed in. */
1312 find_regno_partial (rtx
*ptr
, void *data
)
1314 find_regno_partial_param
*param
= (find_regno_partial_param
*)data
;
1315 unsigned reg
= param
->regno_to_find
;
1316 param
->retval
= NULL_RTX
;
1318 if (*ptr
== NULL_RTX
)
1321 switch (GET_CODE (*ptr
))
1325 case STRICT_LOW_PART
:
1326 if (REG_P (XEXP (*ptr
, 0)) && REGNO (XEXP (*ptr
, 0)) == reg
)
1328 param
->retval
= XEXP (*ptr
, 0);
1334 if (REG_P (SUBREG_REG (*ptr
))
1335 && REGNO (SUBREG_REG (*ptr
)) == reg
)
1337 param
->retval
= SUBREG_REG (*ptr
);
1349 /* Process all immediate successors of the entry block looking for pseudo
1350 registers which are live on entry. Find all of those whose first
1351 instance is a partial register reference of some kind, and initialize
1352 them to 0 after the entry block. This will prevent bit sets within
1353 registers whose value is unknown, and may contain some kind of sticky
1354 bits we don't want. */
1357 initialize_uninitialized_subregs (void)
1361 int reg
, did_something
= 0;
1362 find_regno_partial_param param
;
1365 FOR_EACH_EDGE (e
, ei
, ENTRY_BLOCK_PTR
->succs
)
1367 basic_block bb
= e
->dest
;
1368 regset map
= bb
->global_live_at_start
;
1369 reg_set_iterator rsi
;
1371 EXECUTE_IF_SET_IN_REG_SET (map
, FIRST_PSEUDO_REGISTER
, reg
, rsi
)
1373 int uid
= REGNO_FIRST_UID (reg
);
1376 /* Find an insn which mentions the register we are looking for.
1377 Its preferable to have an instance of the register's rtl since
1378 there may be various flags set which we need to duplicate.
1379 If we can't find it, its probably an automatic whose initial
1380 value doesn't matter, or hopefully something we don't care about. */
1381 for (i
= get_insns (); i
&& INSN_UID (i
) != uid
; i
= NEXT_INSN (i
))
1385 /* Found the insn, now get the REG rtx, if we can. */
1386 param
.regno_to_find
= reg
;
1387 for_each_rtx (&i
, find_regno_partial
, ¶m
);
1388 if (param
.retval
!= NULL_RTX
)
1391 emit_move_insn (param
.retval
,
1392 CONST0_RTX (GET_MODE (param
.retval
)));
1393 insn
= get_insns ();
1395 insert_insn_on_edge (insn
, e
);
1403 commit_edge_insertions ();
1404 return did_something
;
1408 /* Subroutines of life analysis. */
1410 /* Allocate the permanent data structures that represent the results
1411 of life analysis. Not static since used also for stupid life analysis. */
1414 allocate_bb_life_data (void)
1418 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
, NULL
, next_bb
)
1420 bb
->global_live_at_start
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1421 bb
->global_live_at_end
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1424 regs_live_at_setjmp
= OBSTACK_ALLOC_REG_SET (&flow_obstack
);
1428 allocate_reg_life_data (void)
1432 max_regno
= max_reg_num ();
1433 gcc_assert (!reg_deaths
);
1434 reg_deaths
= xcalloc (sizeof (*reg_deaths
), max_regno
);
1436 /* Recalculate the register space, in case it has grown. Old style
1437 vector oriented regsets would set regset_{size,bytes} here also. */
1438 allocate_reg_info (max_regno
, FALSE
, FALSE
);
1440 /* Reset all the data we'll collect in propagate_block and its
1442 for (i
= 0; i
< max_regno
; i
++)
1446 REG_N_DEATHS (i
) = 0;
1447 REG_N_CALLS_CROSSED (i
) = 0;
1448 REG_LIVE_LENGTH (i
) = 0;
1450 REG_BASIC_BLOCK (i
) = REG_BLOCK_UNKNOWN
;
1454 /* Delete dead instructions for propagate_block. */
1457 propagate_block_delete_insn (rtx insn
)
1459 rtx inote
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
);
1461 /* If the insn referred to a label, and that label was attached to
1462 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1463 pretty much mandatory to delete it, because the ADDR_VEC may be
1464 referencing labels that no longer exist.
1466 INSN may reference a deleted label, particularly when a jump
1467 table has been optimized into a direct jump. There's no
1468 real good way to fix up the reference to the deleted label
1469 when the label is deleted, so we just allow it here. */
1471 if (inote
&& LABEL_P (inote
))
1473 rtx label
= XEXP (inote
, 0);
1476 /* The label may be forced if it has been put in the constant
1477 pool. If that is the only use we must discard the table
1478 jump following it, but not the label itself. */
1479 if (LABEL_NUSES (label
) == 1 + LABEL_PRESERVE_P (label
)
1480 && (next
= next_nonnote_insn (label
)) != NULL
1482 && (GET_CODE (PATTERN (next
)) == ADDR_VEC
1483 || GET_CODE (PATTERN (next
)) == ADDR_DIFF_VEC
))
1485 rtx pat
= PATTERN (next
);
1486 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
1487 int len
= XVECLEN (pat
, diff_vec_p
);
1490 for (i
= 0; i
< len
; i
++)
1491 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))--;
1493 delete_insn_and_edges (next
);
1498 delete_insn_and_edges (insn
);
1502 /* Delete dead libcalls for propagate_block. Return the insn
1503 before the libcall. */
1506 propagate_block_delete_libcall (rtx insn
, rtx note
)
1508 rtx first
= XEXP (note
, 0);
1509 rtx before
= PREV_INSN (first
);
1511 delete_insn_chain_and_edges (first
, insn
);
1516 /* Update the life-status of regs for one insn. Return the previous insn. */
1519 propagate_one_insn (struct propagate_block_info
*pbi
, rtx insn
)
1521 rtx prev
= PREV_INSN (insn
);
1522 int flags
= pbi
->flags
;
1523 int insn_is_dead
= 0;
1524 int libcall_is_dead
= 0;
1528 if (! INSN_P (insn
))
1531 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
1532 if (flags
& PROP_SCAN_DEAD_CODE
)
1534 insn_is_dead
= insn_dead_p (pbi
, PATTERN (insn
), 0, REG_NOTES (insn
));
1535 libcall_is_dead
= (insn_is_dead
&& note
!= 0
1536 && libcall_dead_p (pbi
, note
, insn
));
1539 /* If an instruction consists of just dead store(s) on final pass,
1541 if ((flags
& PROP_KILL_DEAD_CODE
) && insn_is_dead
)
1543 /* If we're trying to delete a prologue or epilogue instruction
1544 that isn't flagged as possibly being dead, something is wrong.
1545 But if we are keeping the stack pointer depressed, we might well
1546 be deleting insns that are used to compute the amount to update
1547 it by, so they are fine. */
1548 if (reload_completed
1549 && !(TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1550 && (TYPE_RETURNS_STACK_DEPRESSED
1551 (TREE_TYPE (current_function_decl
))))
1552 && (((HAVE_epilogue
|| HAVE_prologue
)
1553 && prologue_epilogue_contains (insn
))
1554 || (HAVE_sibcall_epilogue
1555 && sibcall_epilogue_contains (insn
)))
1556 && find_reg_note (insn
, REG_MAYBE_DEAD
, NULL_RTX
) == 0)
1557 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn
);
1559 /* Record sets. Do this even for dead instructions, since they
1560 would have killed the values if they hadn't been deleted. */
1561 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1563 /* CC0 is now known to be dead. Either this insn used it,
1564 in which case it doesn't anymore, or clobbered it,
1565 so the next insn can't use it. */
1568 if (libcall_is_dead
)
1569 prev
= propagate_block_delete_libcall ( insn
, note
);
1573 /* If INSN contains a RETVAL note and is dead, but the libcall
1574 as a whole is not dead, then we want to remove INSN, but
1575 not the whole libcall sequence.
1577 However, we need to also remove the dangling REG_LIBCALL
1578 note so that we do not have mis-matched LIBCALL/RETVAL
1579 notes. In theory we could find a new location for the
1580 REG_RETVAL note, but it hardly seems worth the effort.
1582 NOTE at this point will be the RETVAL note if it exists. */
1588 = find_reg_note (XEXP (note
, 0), REG_LIBCALL
, NULL_RTX
);
1589 remove_note (XEXP (note
, 0), libcall_note
);
1592 /* Similarly if INSN contains a LIBCALL note, remove the
1593 dangling REG_RETVAL note. */
1594 note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
);
1600 = find_reg_note (XEXP (note
, 0), REG_RETVAL
, NULL_RTX
);
1601 remove_note (XEXP (note
, 0), retval_note
);
1604 /* Now delete INSN. */
1605 propagate_block_delete_insn (insn
);
1611 /* See if this is an increment or decrement that can be merged into
1612 a following memory address. */
1615 rtx x
= single_set (insn
);
1617 /* Does this instruction increment or decrement a register? */
1618 if ((flags
& PROP_AUTOINC
)
1620 && REG_P (SET_DEST (x
))
1621 && (GET_CODE (SET_SRC (x
)) == PLUS
1622 || GET_CODE (SET_SRC (x
)) == MINUS
)
1623 && XEXP (SET_SRC (x
), 0) == SET_DEST (x
)
1624 && GET_CODE (XEXP (SET_SRC (x
), 1)) == CONST_INT
1625 /* Ok, look for a following memory ref we can combine with.
1626 If one is found, change the memory ref to a PRE_INC
1627 or PRE_DEC, cancel this insn, and return 1.
1628 Return 0 if nothing has been done. */
1629 && try_pre_increment_1 (pbi
, insn
))
1632 #endif /* AUTO_INC_DEC */
1634 CLEAR_REG_SET (pbi
->new_set
);
1636 /* If this is not the final pass, and this insn is copying the value of
1637 a library call and it's dead, don't scan the insns that perform the
1638 library call, so that the call's arguments are not marked live. */
1639 if (libcall_is_dead
)
1641 /* Record the death of the dest reg. */
1642 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1644 insn
= XEXP (note
, 0);
1645 return PREV_INSN (insn
);
1647 else if (GET_CODE (PATTERN (insn
)) == SET
1648 && SET_DEST (PATTERN (insn
)) == stack_pointer_rtx
1649 && GET_CODE (SET_SRC (PATTERN (insn
))) == PLUS
1650 && XEXP (SET_SRC (PATTERN (insn
)), 0) == stack_pointer_rtx
1651 && GET_CODE (XEXP (SET_SRC (PATTERN (insn
)), 1)) == CONST_INT
)
1653 /* We have an insn to pop a constant amount off the stack.
1654 (Such insns use PLUS regardless of the direction of the stack,
1655 and any insn to adjust the stack by a constant is always a pop
1657 These insns, if not dead stores, have no effect on life, though
1658 they do have an effect on the memory stores we are tracking. */
1659 invalidate_mems_from_set (pbi
, stack_pointer_rtx
);
1660 /* Still, we need to update local_set, lest ifcvt.c:dead_or_predicable
1661 concludes that the stack pointer is not modified. */
1662 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1667 /* Any regs live at the time of a call instruction must not go
1668 in a register clobbered by calls. Find all regs now live and
1669 record this for them. */
1671 if (CALL_P (insn
) && (flags
& PROP_REG_INFO
))
1673 reg_set_iterator rsi
;
1674 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
, rsi
)
1675 REG_N_CALLS_CROSSED (i
)++;
1678 /* Record sets. Do this even for dead instructions, since they
1679 would have killed the values if they hadn't been deleted. */
1680 mark_set_regs (pbi
, PATTERN (insn
), insn
);
1690 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1691 cond
= COND_EXEC_TEST (PATTERN (insn
));
1693 /* Non-constant calls clobber memory, constant calls do not
1694 clobber memory, though they may clobber outgoing arguments
1696 if (! CONST_OR_PURE_CALL_P (insn
))
1698 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1699 pbi
->mem_set_list_len
= 0;
1702 invalidate_mems_from_set (pbi
, stack_pointer_rtx
);
1704 /* There may be extra registers to be clobbered. */
1705 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
1707 note
= XEXP (note
, 1))
1708 if (GET_CODE (XEXP (note
, 0)) == CLOBBER
)
1709 mark_set_1 (pbi
, CLOBBER
, XEXP (XEXP (note
, 0), 0),
1710 cond
, insn
, pbi
->flags
);
1712 /* Calls change all call-used and global registers; sibcalls do not
1713 clobber anything that must be preserved at end-of-function,
1714 except for return values. */
1716 sibcall_p
= SIBLING_CALL_P (insn
);
1717 live_at_end
= EXIT_BLOCK_PTR
->global_live_at_start
;
1718 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1719 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
)
1721 && REGNO_REG_SET_P (live_at_end
, i
)
1722 && ! refers_to_regno_p (i
, i
+1,
1723 current_function_return_rtx
,
1726 enum rtx_code code
= global_regs
[i
] ? SET
: CLOBBER
;
1727 /* We do not want REG_UNUSED notes for these registers. */
1728 mark_set_1 (pbi
, code
, regno_reg_rtx
[i
], cond
, insn
,
1729 pbi
->flags
& ~(PROP_DEATH_NOTES
| PROP_REG_INFO
));
1733 /* If an insn doesn't use CC0, it becomes dead since we assume
1734 that every insn clobbers it. So show it dead here;
1735 mark_used_regs will set it live if it is referenced. */
1740 mark_used_regs (pbi
, PATTERN (insn
), NULL_RTX
, insn
);
1741 if ((flags
& PROP_EQUAL_NOTES
)
1742 && ((note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
))
1743 || (note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
))))
1744 mark_used_regs (pbi
, XEXP (note
, 0), NULL_RTX
, insn
);
1746 /* Sometimes we may have inserted something before INSN (such as a move)
1747 when we make an auto-inc. So ensure we will scan those insns. */
1749 prev
= PREV_INSN (insn
);
1752 if (! insn_is_dead
&& CALL_P (insn
))
1758 if (GET_CODE (PATTERN (insn
)) == COND_EXEC
)
1759 cond
= COND_EXEC_TEST (PATTERN (insn
));
1761 /* Calls use their arguments, and may clobber memory which
1762 address involves some register. */
1763 for (note
= CALL_INSN_FUNCTION_USAGE (insn
);
1765 note
= XEXP (note
, 1))
1766 /* We find USE or CLOBBER entities in a FUNCTION_USAGE list: both
1767 of which mark_used_regs knows how to handle. */
1768 mark_used_regs (pbi
, XEXP (XEXP (note
, 0), 0), cond
, insn
);
1770 /* The stack ptr is used (honorarily) by a CALL insn. */
1771 if ((flags
& PROP_REG_INFO
)
1772 && !REGNO_REG_SET_P (pbi
->reg_live
, STACK_POINTER_REGNUM
))
1773 reg_deaths
[STACK_POINTER_REGNUM
] = pbi
->insn_num
;
1774 SET_REGNO_REG_SET (pbi
->reg_live
, STACK_POINTER_REGNUM
);
1776 /* Calls may also reference any of the global registers,
1777 so they are made live. */
1778 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
1780 mark_used_reg (pbi
, regno_reg_rtx
[i
], cond
, insn
);
1789 /* Initialize a propagate_block_info struct for public consumption.
1790 Note that the structure itself is opaque to this file, but that
1791 the user can use the regsets provided here. */
1793 struct propagate_block_info
*
1794 init_propagate_block_info (basic_block bb
, regset live
, regset local_set
,
1795 regset cond_local_set
, int flags
)
1797 struct propagate_block_info
*pbi
= xmalloc (sizeof (*pbi
));
1800 pbi
->reg_live
= live
;
1801 pbi
->mem_set_list
= NULL_RTX
;
1802 pbi
->mem_set_list_len
= 0;
1803 pbi
->local_set
= local_set
;
1804 pbi
->cond_local_set
= cond_local_set
;
1809 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
1810 pbi
->reg_next_use
= xcalloc (max_reg_num (), sizeof (rtx
));
1812 pbi
->reg_next_use
= NULL
;
1814 pbi
->new_set
= BITMAP_XMALLOC ();
1816 #ifdef HAVE_conditional_execution
1817 pbi
->reg_cond_dead
= splay_tree_new (splay_tree_compare_ints
, NULL
,
1818 free_reg_cond_life_info
);
1819 pbi
->reg_cond_reg
= BITMAP_XMALLOC ();
1821 /* If this block ends in a conditional branch, for each register
1822 live from one side of the branch and not the other, record the
1823 register as conditionally dead. */
1824 if (JUMP_P (BB_END (bb
))
1825 && any_condjump_p (BB_END (bb
)))
1827 regset_head diff_head
;
1828 regset diff
= INITIALIZE_REG_SET (diff_head
);
1829 basic_block bb_true
, bb_false
;
1832 /* Identify the successor blocks. */
1833 bb_true
= EDGE_SUCC (bb
, 0)->dest
;
1834 if (EDGE_COUNT (bb
->succs
) > 1)
1836 bb_false
= EDGE_SUCC (bb
, 1)->dest
;
1838 if (EDGE_SUCC (bb
, 0)->flags
& EDGE_FALLTHRU
)
1840 basic_block t
= bb_false
;
1845 gcc_assert (EDGE_SUCC (bb
, 1)->flags
& EDGE_FALLTHRU
);
1849 /* This can happen with a conditional jump to the next insn. */
1850 gcc_assert (JUMP_LABEL (BB_END (bb
)) == BB_HEAD (bb_true
));
1852 /* Simplest way to do nothing. */
1856 /* Compute which register lead different lives in the successors. */
1857 if (bitmap_xor (diff
, bb_true
->global_live_at_start
,
1858 bb_false
->global_live_at_start
))
1860 /* Extract the condition from the branch. */
1861 rtx set_src
= SET_SRC (pc_set (BB_END (bb
)));
1862 rtx cond_true
= XEXP (set_src
, 0);
1863 rtx reg
= XEXP (cond_true
, 0);
1864 enum rtx_code inv_cond
;
1866 if (GET_CODE (reg
) == SUBREG
)
1867 reg
= SUBREG_REG (reg
);
1869 /* We can only track conditional lifetimes if the condition is
1870 in the form of a reversible comparison of a register against
1871 zero. If the condition is more complex than that, then it is
1872 safe not to record any information. */
1873 inv_cond
= reversed_comparison_code (cond_true
, BB_END (bb
));
1874 if (inv_cond
!= UNKNOWN
1876 && XEXP (cond_true
, 1) == const0_rtx
)
1879 = gen_rtx_fmt_ee (inv_cond
,
1880 GET_MODE (cond_true
), XEXP (cond_true
, 0),
1881 XEXP (cond_true
, 1));
1882 reg_set_iterator rsi
;
1884 if (GET_CODE (XEXP (set_src
, 1)) == PC
)
1887 cond_false
= cond_true
;
1891 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (reg
));
1893 /* For each such register, mark it conditionally dead. */
1894 EXECUTE_IF_SET_IN_REG_SET (diff
, 0, i
, rsi
)
1896 struct reg_cond_life_info
*rcli
;
1899 rcli
= xmalloc (sizeof (*rcli
));
1901 if (REGNO_REG_SET_P (bb_true
->global_live_at_start
, i
))
1905 rcli
->condition
= cond
;
1906 rcli
->stores
= const0_rtx
;
1907 rcli
->orig_condition
= cond
;
1909 splay_tree_insert (pbi
->reg_cond_dead
, i
,
1910 (splay_tree_value
) rcli
);
1915 FREE_REG_SET (diff
);
1919 /* If this block has no successors, any stores to the frame that aren't
1920 used later in the block are dead. So make a pass over the block
1921 recording any such that are made and show them dead at the end. We do
1922 a very conservative and simple job here. */
1924 && ! (TREE_CODE (TREE_TYPE (current_function_decl
)) == FUNCTION_TYPE
1925 && (TYPE_RETURNS_STACK_DEPRESSED
1926 (TREE_TYPE (current_function_decl
))))
1927 && (flags
& PROP_SCAN_DEAD_STORES
)
1928 && (EDGE_COUNT (bb
->succs
) == 0
1929 || (EDGE_COUNT (bb
->succs
) == 1
1930 && EDGE_SUCC (bb
, 0)->dest
== EXIT_BLOCK_PTR
1931 && ! current_function_calls_eh_return
)))
1934 for (insn
= BB_END (bb
); insn
!= BB_HEAD (bb
); insn
= PREV_INSN (insn
))
1935 if (NONJUMP_INSN_P (insn
)
1936 && (set
= single_set (insn
))
1937 && MEM_P (SET_DEST (set
)))
1939 rtx mem
= SET_DEST (set
);
1940 rtx canon_mem
= canon_rtx (mem
);
1942 if (XEXP (canon_mem
, 0) == frame_pointer_rtx
1943 || (GET_CODE (XEXP (canon_mem
, 0)) == PLUS
1944 && XEXP (XEXP (canon_mem
, 0), 0) == frame_pointer_rtx
1945 && GET_CODE (XEXP (XEXP (canon_mem
, 0), 1)) == CONST_INT
))
1946 add_to_mem_set_list (pbi
, canon_mem
);
1953 /* Release a propagate_block_info struct. */
1956 free_propagate_block_info (struct propagate_block_info
*pbi
)
1958 free_EXPR_LIST_list (&pbi
->mem_set_list
);
1960 BITMAP_XFREE (pbi
->new_set
);
1962 #ifdef HAVE_conditional_execution
1963 splay_tree_delete (pbi
->reg_cond_dead
);
1964 BITMAP_XFREE (pbi
->reg_cond_reg
);
1967 if (pbi
->flags
& PROP_REG_INFO
)
1969 int num
= pbi
->insn_num
;
1971 reg_set_iterator rsi
;
1973 EXECUTE_IF_SET_IN_REG_SET (pbi
->reg_live
, 0, i
, rsi
)
1975 REG_LIVE_LENGTH (i
) += num
- reg_deaths
[i
];
1979 if (pbi
->reg_next_use
)
1980 free (pbi
->reg_next_use
);
1985 /* Compute the registers live at the beginning of a basic block BB from
1986 those live at the end.
1988 When called, REG_LIVE contains those live at the end. On return, it
1989 contains those live at the beginning.
1991 LOCAL_SET, if non-null, will be set with all registers killed
1992 unconditionally by this basic block.
1993 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
1994 killed conditionally by this basic block. If there is any unconditional
1995 set of a register, then the corresponding bit will be set in LOCAL_SET
1996 and cleared in COND_LOCAL_SET.
1997 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
1998 case, the resulting set will be equal to the union of the two sets that
1999 would otherwise be computed.
2001 Return nonzero if an INSN is deleted (i.e. by dead code removal). */
2004 propagate_block (basic_block bb
, regset live
, regset local_set
,
2005 regset cond_local_set
, int flags
)
2007 struct propagate_block_info
*pbi
;
2011 pbi
= init_propagate_block_info (bb
, live
, local_set
, cond_local_set
, flags
);
2013 if (flags
& PROP_REG_INFO
)
2016 reg_set_iterator rsi
;
2018 /* Process the regs live at the end of the block.
2019 Mark them as not local to any one basic block. */
2020 EXECUTE_IF_SET_IN_REG_SET (live
, 0, i
, rsi
)
2021 REG_BASIC_BLOCK (i
) = REG_BLOCK_GLOBAL
;
2024 /* Scan the block an insn at a time from end to beginning. */
2027 for (insn
= BB_END (bb
); ; insn
= prev
)
2029 /* If this is a call to `setjmp' et al, warn if any
2030 non-volatile datum is live. */
2031 if ((flags
& PROP_REG_INFO
)
2033 && find_reg_note (insn
, REG_SETJMP
, NULL
))
2034 IOR_REG_SET (regs_live_at_setjmp
, pbi
->reg_live
);
2036 prev
= propagate_one_insn (pbi
, insn
);
2038 changed
|= insn
!= get_insns ();
2040 changed
|= NEXT_INSN (prev
) != insn
;
2042 if (insn
== BB_HEAD (bb
))
2046 free_propagate_block_info (pbi
);
2051 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2052 (SET expressions whose destinations are registers dead after the insn).
2053 NEEDED is the regset that says which regs are alive after the insn.
2055 Unless CALL_OK is nonzero, an insn is needed if it contains a CALL.
2057 If X is the entire body of an insn, NOTES contains the reg notes
2058 pertaining to the insn. */
2061 insn_dead_p (struct propagate_block_info
*pbi
, rtx x
, int call_ok
,
2062 rtx notes ATTRIBUTE_UNUSED
)
2064 enum rtx_code code
= GET_CODE (x
);
2066 /* Don't eliminate insns that may trap. */
2067 if (flag_non_call_exceptions
&& may_trap_p (x
))
2071 /* As flow is invoked after combine, we must take existing AUTO_INC
2072 expressions into account. */
2073 for (; notes
; notes
= XEXP (notes
, 1))
2075 if (REG_NOTE_KIND (notes
) == REG_INC
)
2077 int regno
= REGNO (XEXP (notes
, 0));
2079 /* Don't delete insns to set global regs. */
2080 if ((regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2081 || REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2087 /* If setting something that's a reg or part of one,
2088 see if that register's altered value will be live. */
2092 rtx r
= SET_DEST (x
);
2095 if (GET_CODE (r
) == CC0
)
2096 return ! pbi
->cc0_live
;
2099 /* A SET that is a subroutine call cannot be dead. */
2100 if (GET_CODE (SET_SRC (x
)) == CALL
)
2106 /* Don't eliminate loads from volatile memory or volatile asms. */
2107 else if (volatile_refs_p (SET_SRC (x
)))
2114 if (MEM_VOLATILE_P (r
) || GET_MODE (r
) == BLKmode
)
2117 canon_r
= canon_rtx (r
);
2119 /* Walk the set of memory locations we are currently tracking
2120 and see if one is an identical match to this memory location.
2121 If so, this memory write is dead (remember, we're walking
2122 backwards from the end of the block to the start). Since
2123 rtx_equal_p does not check the alias set or flags, we also
2124 must have the potential for them to conflict (anti_dependence). */
2125 for (temp
= pbi
->mem_set_list
; temp
!= 0; temp
= XEXP (temp
, 1))
2126 if (anti_dependence (r
, XEXP (temp
, 0)))
2128 rtx mem
= XEXP (temp
, 0);
2130 if (rtx_equal_p (XEXP (canon_r
, 0), XEXP (mem
, 0))
2131 && (GET_MODE_SIZE (GET_MODE (canon_r
))
2132 <= GET_MODE_SIZE (GET_MODE (mem
))))
2136 /* Check if memory reference matches an auto increment. Only
2137 post increment/decrement or modify are valid. */
2138 if (GET_MODE (mem
) == GET_MODE (r
)
2139 && (GET_CODE (XEXP (mem
, 0)) == POST_DEC
2140 || GET_CODE (XEXP (mem
, 0)) == POST_INC
2141 || GET_CODE (XEXP (mem
, 0)) == POST_MODIFY
)
2142 && GET_MODE (XEXP (mem
, 0)) == GET_MODE (r
)
2143 && rtx_equal_p (XEXP (XEXP (mem
, 0), 0), XEXP (r
, 0)))
2150 while (GET_CODE (r
) == SUBREG
2151 || GET_CODE (r
) == STRICT_LOW_PART
2152 || GET_CODE (r
) == ZERO_EXTRACT
)
2157 int regno
= REGNO (r
);
2160 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
))
2163 /* If this is a hard register, verify that subsequent
2164 words are not needed. */
2165 if (regno
< FIRST_PSEUDO_REGISTER
)
2167 int n
= hard_regno_nregs
[regno
][GET_MODE (r
)];
2170 if (REGNO_REG_SET_P (pbi
->reg_live
, regno
+n
))
2174 /* Don't delete insns to set global regs. */
2175 if (regno
< FIRST_PSEUDO_REGISTER
&& global_regs
[regno
])
2178 /* Make sure insns to set the stack pointer aren't deleted. */
2179 if (regno
== STACK_POINTER_REGNUM
)
2182 /* ??? These bits might be redundant with the force live bits
2183 in calculate_global_regs_live. We would delete from
2184 sequential sets; whether this actually affects real code
2185 for anything but the stack pointer I don't know. */
2186 /* Make sure insns to set the frame pointer aren't deleted. */
2187 if (regno
== FRAME_POINTER_REGNUM
2188 && (! reload_completed
|| frame_pointer_needed
))
2190 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2191 if (regno
== HARD_FRAME_POINTER_REGNUM
2192 && (! reload_completed
|| frame_pointer_needed
))
2196 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2197 /* Make sure insns to set arg pointer are never deleted
2198 (if the arg pointer isn't fixed, there will be a USE
2199 for it, so we can treat it normally). */
2200 if (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
2204 /* Otherwise, the set is dead. */
2210 /* If performing several activities, insn is dead if each activity
2211 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2212 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2214 else if (code
== PARALLEL
)
2216 int i
= XVECLEN (x
, 0);
2218 for (i
--; i
>= 0; i
--)
2219 if (GET_CODE (XVECEXP (x
, 0, i
)) != CLOBBER
2220 && GET_CODE (XVECEXP (x
, 0, i
)) != USE
2221 && ! insn_dead_p (pbi
, XVECEXP (x
, 0, i
), call_ok
, NULL_RTX
))
2227 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2228 is not necessarily true for hard registers until after reload. */
2229 else if (code
== CLOBBER
)
2231 if (REG_P (XEXP (x
, 0))
2232 && (REGNO (XEXP (x
, 0)) >= FIRST_PSEUDO_REGISTER
2233 || reload_completed
)
2234 && ! REGNO_REG_SET_P (pbi
->reg_live
, REGNO (XEXP (x
, 0))))
2238 /* ??? A base USE is a historical relic. It ought not be needed anymore.
2239 Instances where it is still used are either (1) temporary and the USE
2240 escaped the pass, (2) cruft and the USE need not be emitted anymore,
2241 or (3) hiding bugs elsewhere that are not properly representing data
2247 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2248 return 1 if the entire library call is dead.
2249 This is true if INSN copies a register (hard or pseudo)
2250 and if the hard return reg of the call insn is dead.
2251 (The caller should have tested the destination of the SET inside
2252 INSN already for death.)
2254 If this insn doesn't just copy a register, then we don't
2255 have an ordinary libcall. In that case, cse could not have
2256 managed to substitute the source for the dest later on,
2257 so we can assume the libcall is dead.
2259 PBI is the block info giving pseudoregs live before this insn.
2260 NOTE is the REG_RETVAL note of the insn. */
2263 libcall_dead_p (struct propagate_block_info
*pbi
, rtx note
, rtx insn
)
2265 rtx x
= single_set (insn
);
2269 rtx r
= SET_SRC (x
);
2273 rtx call
= XEXP (note
, 0);
2277 /* Find the call insn. */
2278 while (call
!= insn
&& !CALL_P (call
))
2279 call
= NEXT_INSN (call
);
2281 /* If there is none, do nothing special,
2282 since ordinary death handling can understand these insns. */
2286 /* See if the hard reg holding the value is dead.
2287 If this is a PARALLEL, find the call within it. */
2288 call_pat
= PATTERN (call
);
2289 if (GET_CODE (call_pat
) == PARALLEL
)
2291 for (i
= XVECLEN (call_pat
, 0) - 1; i
>= 0; i
--)
2292 if (GET_CODE (XVECEXP (call_pat
, 0, i
)) == SET
2293 && GET_CODE (SET_SRC (XVECEXP (call_pat
, 0, i
))) == CALL
)
2296 /* This may be a library call that is returning a value
2297 via invisible pointer. Do nothing special, since
2298 ordinary death handling can understand these insns. */
2302 call_pat
= XVECEXP (call_pat
, 0, i
);
2305 return insn_dead_p (pbi
, call_pat
, 1, REG_NOTES (call
));
2311 /* 1 if register REGNO was alive at a place where `setjmp' was called
2312 and was set more than once or is an argument.
2313 Such regs may be clobbered by `longjmp'. */
2316 regno_clobbered_at_setjmp (int regno
)
2318 if (n_basic_blocks
== 0)
2321 return ((REG_N_SETS (regno
) > 1
2322 || REGNO_REG_SET_P (ENTRY_BLOCK_PTR
->global_live_at_end
, regno
))
2323 && REGNO_REG_SET_P (regs_live_at_setjmp
, regno
));
2326 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2327 maximal list size; look for overlaps in mode and select the largest. */
2329 add_to_mem_set_list (struct propagate_block_info
*pbi
, rtx mem
)
2333 /* We don't know how large a BLKmode store is, so we must not
2334 take them into consideration. */
2335 if (GET_MODE (mem
) == BLKmode
)
2338 for (i
= pbi
->mem_set_list
; i
; i
= XEXP (i
, 1))
2340 rtx e
= XEXP (i
, 0);
2341 if (rtx_equal_p (XEXP (mem
, 0), XEXP (e
, 0)))
2343 if (GET_MODE_SIZE (GET_MODE (mem
)) > GET_MODE_SIZE (GET_MODE (e
)))
2346 /* If we must store a copy of the mem, we can just modify
2347 the mode of the stored copy. */
2348 if (pbi
->flags
& PROP_AUTOINC
)
2349 PUT_MODE (e
, GET_MODE (mem
));
2358 if (pbi
->mem_set_list_len
< MAX_MEM_SET_LIST_LEN
)
2361 /* Store a copy of mem, otherwise the address may be
2362 scrogged by find_auto_inc. */
2363 if (pbi
->flags
& PROP_AUTOINC
)
2364 mem
= shallow_copy_rtx (mem
);
2366 pbi
->mem_set_list
= alloc_EXPR_LIST (0, mem
, pbi
->mem_set_list
);
2367 pbi
->mem_set_list_len
++;
2371 /* INSN references memory, possibly using autoincrement addressing modes.
2372 Find any entries on the mem_set_list that need to be invalidated due
2373 to an address change. */
2376 invalidate_mems_from_autoinc (rtx
*px
, void *data
)
2379 struct propagate_block_info
*pbi
= data
;
2381 if (GET_RTX_CLASS (GET_CODE (x
)) == RTX_AUTOINC
)
2383 invalidate_mems_from_set (pbi
, XEXP (x
, 0));
2390 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2393 invalidate_mems_from_set (struct propagate_block_info
*pbi
, rtx exp
)
2395 rtx temp
= pbi
->mem_set_list
;
2396 rtx prev
= NULL_RTX
;
2401 next
= XEXP (temp
, 1);
2402 if (reg_overlap_mentioned_p (exp
, XEXP (temp
, 0)))
2404 /* Splice this entry out of the list. */
2406 XEXP (prev
, 1) = next
;
2408 pbi
->mem_set_list
= next
;
2409 free_EXPR_LIST_node (temp
);
2410 pbi
->mem_set_list_len
--;
2418 /* Process the registers that are set within X. Their bits are set to
2419 1 in the regset DEAD, because they are dead prior to this insn.
2421 If INSN is nonzero, it is the insn being processed.
2423 FLAGS is the set of operations to perform. */
2426 mark_set_regs (struct propagate_block_info
*pbi
, rtx x
, rtx insn
)
2428 rtx cond
= NULL_RTX
;
2431 int flags
= pbi
->flags
;
2434 for (link
= REG_NOTES (insn
); link
; link
= XEXP (link
, 1))
2436 if (REG_NOTE_KIND (link
) == REG_INC
)
2437 mark_set_1 (pbi
, SET
, XEXP (link
, 0),
2438 (GET_CODE (x
) == COND_EXEC
2439 ? COND_EXEC_TEST (x
) : NULL_RTX
),
2443 switch (code
= GET_CODE (x
))
2446 if (GET_CODE (XEXP (x
, 1)) == ASM_OPERANDS
)
2447 flags
|= PROP_ASM_SCAN
;
2450 mark_set_1 (pbi
, code
, SET_DEST (x
), cond
, insn
, flags
);
2454 cond
= COND_EXEC_TEST (x
);
2455 x
= COND_EXEC_CODE (x
);
2462 /* We must scan forwards. If we have an asm, we need to set
2463 the PROP_ASM_SCAN flag before scanning the clobbers. */
2464 for (i
= 0; i
< XVECLEN (x
, 0); i
++)
2466 rtx sub
= XVECEXP (x
, 0, i
);
2467 switch (code
= GET_CODE (sub
))
2472 cond
= COND_EXEC_TEST (sub
);
2473 sub
= COND_EXEC_CODE (sub
);
2474 if (GET_CODE (sub
) == SET
)
2476 if (GET_CODE (sub
) == CLOBBER
)
2482 if (GET_CODE (XEXP (sub
, 1)) == ASM_OPERANDS
)
2483 flags
|= PROP_ASM_SCAN
;
2487 mark_set_1 (pbi
, code
, SET_DEST (sub
), cond
, insn
, flags
);
2491 flags
|= PROP_ASM_SCAN
;
2506 /* Process a single set, which appears in INSN. REG (which may not
2507 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2508 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2509 If the set is conditional (because it appear in a COND_EXEC), COND
2510 will be the condition. */
2513 mark_set_1 (struct propagate_block_info
*pbi
, enum rtx_code code
, rtx reg
, rtx cond
, rtx insn
, int flags
)
2515 int regno_first
= -1, regno_last
= -1;
2516 unsigned long not_dead
= 0;
2519 /* Modifying just one hardware register of a multi-reg value or just a
2520 byte field of a register does not mean the value from before this insn
2521 is now dead. Of course, if it was dead after it's unused now. */
2523 switch (GET_CODE (reg
))
2526 /* Some targets place small structures in registers for return values of
2527 functions. We have to detect this case specially here to get correct
2528 flow information. */
2529 for (i
= XVECLEN (reg
, 0) - 1; i
>= 0; i
--)
2530 if (XEXP (XVECEXP (reg
, 0, i
), 0) != 0)
2531 mark_set_1 (pbi
, code
, XEXP (XVECEXP (reg
, 0, i
), 0), cond
, insn
,
2537 case STRICT_LOW_PART
:
2538 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2540 reg
= XEXP (reg
, 0);
2541 while (GET_CODE (reg
) == SUBREG
2542 || GET_CODE (reg
) == ZERO_EXTRACT
2543 || GET_CODE (reg
) == SIGN_EXTRACT
2544 || GET_CODE (reg
) == STRICT_LOW_PART
);
2547 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
, REGNO (reg
));
2551 regno_last
= regno_first
= REGNO (reg
);
2552 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2553 regno_last
+= hard_regno_nregs
[regno_first
][GET_MODE (reg
)] - 1;
2557 if (REG_P (SUBREG_REG (reg
)))
2559 enum machine_mode outer_mode
= GET_MODE (reg
);
2560 enum machine_mode inner_mode
= GET_MODE (SUBREG_REG (reg
));
2562 /* Identify the range of registers affected. This is moderately
2563 tricky for hard registers. See alter_subreg. */
2565 regno_last
= regno_first
= REGNO (SUBREG_REG (reg
));
2566 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2568 regno_first
+= subreg_regno_offset (regno_first
, inner_mode
,
2571 regno_last
= (regno_first
2572 + hard_regno_nregs
[regno_first
][outer_mode
] - 1);
2574 /* Since we've just adjusted the register number ranges, make
2575 sure REG matches. Otherwise some_was_live will be clear
2576 when it shouldn't have been, and we'll create incorrect
2577 REG_UNUSED notes. */
2578 reg
= gen_rtx_REG (outer_mode
, regno_first
);
2582 /* If the number of words in the subreg is less than the number
2583 of words in the full register, we have a well-defined partial
2584 set. Otherwise the high bits are undefined.
2586 This is only really applicable to pseudos, since we just took
2587 care of multi-word hard registers. */
2588 if (((GET_MODE_SIZE (outer_mode
)
2589 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
)
2590 < ((GET_MODE_SIZE (inner_mode
)
2591 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
2592 not_dead
= (unsigned long) REGNO_REG_SET_P (pbi
->reg_live
,
2595 reg
= SUBREG_REG (reg
);
2599 reg
= SUBREG_REG (reg
);
2606 /* If this set is a MEM, then it kills any aliased writes.
2607 If this set is a REG, then it kills any MEMs which use the reg. */
2608 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
2611 invalidate_mems_from_set (pbi
, reg
);
2613 /* If the memory reference had embedded side effects (autoincrement
2614 address modes. Then we may need to kill some entries on the
2616 if (insn
&& MEM_P (reg
))
2617 for_each_rtx (&PATTERN (insn
), invalidate_mems_from_autoinc
, pbi
);
2619 if (MEM_P (reg
) && ! side_effects_p (reg
)
2620 /* ??? With more effort we could track conditional memory life. */
2622 add_to_mem_set_list (pbi
, canon_rtx (reg
));
2626 && ! (regno_first
== FRAME_POINTER_REGNUM
2627 && (! reload_completed
|| frame_pointer_needed
))
2628 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2629 && ! (regno_first
== HARD_FRAME_POINTER_REGNUM
2630 && (! reload_completed
|| frame_pointer_needed
))
2632 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2633 && ! (regno_first
== ARG_POINTER_REGNUM
&& fixed_regs
[regno_first
])
2637 int some_was_live
= 0, some_was_dead
= 0;
2639 for (i
= regno_first
; i
<= regno_last
; ++i
)
2641 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
2644 /* Order of the set operation matters here since both
2645 sets may be the same. */
2646 CLEAR_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2647 if (cond
!= NULL_RTX
2648 && ! REGNO_REG_SET_P (pbi
->local_set
, i
))
2649 SET_REGNO_REG_SET (pbi
->cond_local_set
, i
);
2651 SET_REGNO_REG_SET (pbi
->local_set
, i
);
2653 if (code
!= CLOBBER
)
2654 SET_REGNO_REG_SET (pbi
->new_set
, i
);
2656 some_was_live
|= needed_regno
;
2657 some_was_dead
|= ! needed_regno
;
2660 #ifdef HAVE_conditional_execution
2661 /* Consider conditional death in deciding that the register needs
2663 if (some_was_live
&& ! not_dead
2664 /* The stack pointer is never dead. Well, not strictly true,
2665 but it's very difficult to tell from here. Hopefully
2666 combine_stack_adjustments will fix up the most egregious
2668 && regno_first
!= STACK_POINTER_REGNUM
)
2670 for (i
= regno_first
; i
<= regno_last
; ++i
)
2671 if (! mark_regno_cond_dead (pbi
, i
, cond
))
2672 not_dead
|= ((unsigned long) 1) << (i
- regno_first
);
2676 /* Additional data to record if this is the final pass. */
2677 if (flags
& (PROP_LOG_LINKS
| PROP_REG_INFO
2678 | PROP_DEATH_NOTES
| PROP_AUTOINC
))
2681 int blocknum
= pbi
->bb
->index
;
2684 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2686 y
= pbi
->reg_next_use
[regno_first
];
2688 /* The next use is no longer next, since a store intervenes. */
2689 for (i
= regno_first
; i
<= regno_last
; ++i
)
2690 pbi
->reg_next_use
[i
] = 0;
2693 if (flags
& PROP_REG_INFO
)
2695 for (i
= regno_first
; i
<= regno_last
; ++i
)
2697 /* Count (weighted) references, stores, etc. This counts a
2698 register twice if it is modified, but that is correct. */
2699 REG_N_SETS (i
) += 1;
2700 REG_N_REFS (i
) += 1;
2701 REG_FREQ (i
) += REG_FREQ_FROM_BB (pbi
->bb
);
2703 /* The insns where a reg is live are normally counted
2704 elsewhere, but we want the count to include the insn
2705 where the reg is set, and the normal counting mechanism
2706 would not count it. */
2707 REG_LIVE_LENGTH (i
) += 1;
2710 /* If this is a hard reg, record this function uses the reg. */
2711 if (regno_first
< FIRST_PSEUDO_REGISTER
)
2713 for (i
= regno_first
; i
<= regno_last
; i
++)
2714 regs_ever_live
[i
] = 1;
2715 if (flags
& PROP_ASM_SCAN
)
2716 for (i
= regno_first
; i
<= regno_last
; i
++)
2717 regs_asm_clobbered
[i
] = 1;
2721 /* Keep track of which basic blocks each reg appears in. */
2722 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
2723 REG_BASIC_BLOCK (regno_first
) = blocknum
;
2724 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
2725 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
2729 if (! some_was_dead
)
2731 if (flags
& PROP_LOG_LINKS
)
2733 /* Make a logical link from the next following insn
2734 that uses this register, back to this insn.
2735 The following insns have already been processed.
2737 We don't build a LOG_LINK for hard registers containing
2738 in ASM_OPERANDs. If these registers get replaced,
2739 we might wind up changing the semantics of the insn,
2740 even if reload can make what appear to be valid
2743 We don't build a LOG_LINK for global registers to
2744 or from a function call. We don't want to let
2745 combine think that it knows what is going on with
2746 global registers. */
2747 if (y
&& (BLOCK_NUM (y
) == blocknum
)
2748 && (regno_first
>= FIRST_PSEUDO_REGISTER
2749 || (asm_noperands (PATTERN (y
)) < 0
2750 && ! ((CALL_P (insn
)
2752 && global_regs
[regno_first
]))))
2753 LOG_LINKS (y
) = alloc_INSN_LIST (insn
, LOG_LINKS (y
));
2758 else if (! some_was_live
)
2760 if (flags
& PROP_REG_INFO
)
2761 REG_N_DEATHS (regno_first
) += 1;
2763 if (flags
& PROP_DEATH_NOTES
)
2765 /* Note that dead stores have already been deleted
2766 when possible. If we get here, we have found a
2767 dead store that cannot be eliminated (because the
2768 same insn does something useful). Indicate this
2769 by marking the reg being set as dying here. */
2771 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2776 if (flags
& PROP_DEATH_NOTES
)
2778 /* This is a case where we have a multi-word hard register
2779 and some, but not all, of the words of the register are
2780 needed in subsequent insns. Write REG_UNUSED notes
2781 for those parts that were not needed. This case should
2784 for (i
= regno_first
; i
<= regno_last
; ++i
)
2785 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
))
2787 = alloc_EXPR_LIST (REG_UNUSED
,
2794 /* Mark the register as being dead. */
2796 /* The stack pointer is never dead. Well, not strictly true,
2797 but it's very difficult to tell from here. Hopefully
2798 combine_stack_adjustments will fix up the most egregious
2800 && regno_first
!= STACK_POINTER_REGNUM
)
2802 for (i
= regno_first
; i
<= regno_last
; ++i
)
2803 if (!(not_dead
& (((unsigned long) 1) << (i
- regno_first
))))
2805 if ((pbi
->flags
& PROP_REG_INFO
)
2806 && REGNO_REG_SET_P (pbi
->reg_live
, i
))
2808 REG_LIVE_LENGTH (i
) += pbi
->insn_num
- reg_deaths
[i
];
2811 CLEAR_REGNO_REG_SET (pbi
->reg_live
, i
);
2815 else if (REG_P (reg
))
2817 if (flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
2818 pbi
->reg_next_use
[regno_first
] = 0;
2820 if ((flags
& PROP_REG_INFO
) != 0
2821 && (flags
& PROP_ASM_SCAN
) != 0
2822 && regno_first
< FIRST_PSEUDO_REGISTER
)
2824 for (i
= regno_first
; i
<= regno_last
; i
++)
2825 regs_asm_clobbered
[i
] = 1;
2829 /* If this is the last pass and this is a SCRATCH, show it will be dying
2830 here and count it. */
2831 else if (GET_CODE (reg
) == SCRATCH
)
2833 if (flags
& PROP_DEATH_NOTES
)
2835 = alloc_EXPR_LIST (REG_UNUSED
, reg
, REG_NOTES (insn
));
2839 #ifdef HAVE_conditional_execution
2840 /* Mark REGNO conditionally dead.
2841 Return true if the register is now unconditionally dead. */
2844 mark_regno_cond_dead (struct propagate_block_info
*pbi
, int regno
, rtx cond
)
2846 /* If this is a store to a predicate register, the value of the
2847 predicate is changing, we don't know that the predicate as seen
2848 before is the same as that seen after. Flush all dependent
2849 conditions from reg_cond_dead. This will make all such
2850 conditionally live registers unconditionally live. */
2851 if (REGNO_REG_SET_P (pbi
->reg_cond_reg
, regno
))
2852 flush_reg_cond_reg (pbi
, regno
);
2854 /* If this is an unconditional store, remove any conditional
2855 life that may have existed. */
2856 if (cond
== NULL_RTX
)
2857 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2860 splay_tree_node node
;
2861 struct reg_cond_life_info
*rcli
;
2864 /* Otherwise this is a conditional set. Record that fact.
2865 It may have been conditionally used, or there may be a
2866 subsequent set with a complimentary condition. */
2868 node
= splay_tree_lookup (pbi
->reg_cond_dead
, regno
);
2871 /* The register was unconditionally live previously.
2872 Record the current condition as the condition under
2873 which it is dead. */
2874 rcli
= xmalloc (sizeof (*rcli
));
2875 rcli
->condition
= cond
;
2876 rcli
->stores
= cond
;
2877 rcli
->orig_condition
= const0_rtx
;
2878 splay_tree_insert (pbi
->reg_cond_dead
, regno
,
2879 (splay_tree_value
) rcli
);
2881 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2883 /* Not unconditionally dead. */
2888 /* The register was conditionally live previously.
2889 Add the new condition to the old. */
2890 rcli
= (struct reg_cond_life_info
*) node
->value
;
2891 ncond
= rcli
->condition
;
2892 ncond
= ior_reg_cond (ncond
, cond
, 1);
2893 if (rcli
->stores
== const0_rtx
)
2894 rcli
->stores
= cond
;
2895 else if (rcli
->stores
!= const1_rtx
)
2896 rcli
->stores
= ior_reg_cond (rcli
->stores
, cond
, 1);
2898 /* If the register is now unconditionally dead, remove the entry
2899 in the splay_tree. A register is unconditionally dead if the
2900 dead condition ncond is true. A register is also unconditionally
2901 dead if the sum of all conditional stores is an unconditional
2902 store (stores is true), and the dead condition is identically the
2903 same as the original dead condition initialized at the end of
2904 the block. This is a pointer compare, not an rtx_equal_p
2906 if (ncond
== const1_rtx
2907 || (ncond
== rcli
->orig_condition
&& rcli
->stores
== const1_rtx
))
2908 splay_tree_remove (pbi
->reg_cond_dead
, regno
);
2911 rcli
->condition
= ncond
;
2913 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
2915 /* Not unconditionally dead. */
2924 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2927 free_reg_cond_life_info (splay_tree_value value
)
2929 struct reg_cond_life_info
*rcli
= (struct reg_cond_life_info
*) value
;
2933 /* Helper function for flush_reg_cond_reg. */
2936 flush_reg_cond_reg_1 (splay_tree_node node
, void *data
)
2938 struct reg_cond_life_info
*rcli
;
2939 int *xdata
= (int *) data
;
2940 unsigned int regno
= xdata
[0];
2942 /* Don't need to search if last flushed value was farther on in
2943 the in-order traversal. */
2944 if (xdata
[1] >= (int) node
->key
)
2947 /* Splice out portions of the expression that refer to regno. */
2948 rcli
= (struct reg_cond_life_info
*) node
->value
;
2949 rcli
->condition
= elim_reg_cond (rcli
->condition
, regno
);
2950 if (rcli
->stores
!= const0_rtx
&& rcli
->stores
!= const1_rtx
)
2951 rcli
->stores
= elim_reg_cond (rcli
->stores
, regno
);
2953 /* If the entire condition is now false, signal the node to be removed. */
2954 if (rcli
->condition
== const0_rtx
)
2956 xdata
[1] = node
->key
;
2960 gcc_assert (rcli
->condition
!= const1_rtx
);
2965 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2968 flush_reg_cond_reg (struct propagate_block_info
*pbi
, int regno
)
2974 while (splay_tree_foreach (pbi
->reg_cond_dead
,
2975 flush_reg_cond_reg_1
, pair
) == -1)
2976 splay_tree_remove (pbi
->reg_cond_dead
, pair
[1]);
2978 CLEAR_REGNO_REG_SET (pbi
->reg_cond_reg
, regno
);
2981 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2982 For ior/and, the ADD flag determines whether we want to add the new
2983 condition X to the old one unconditionally. If it is zero, we will
2984 only return a new expression if X allows us to simplify part of
2985 OLD, otherwise we return NULL to the caller.
2986 If ADD is nonzero, we will return a new condition in all cases. The
2987 toplevel caller of one of these functions should always pass 1 for
2991 ior_reg_cond (rtx old
, rtx x
, int add
)
2995 if (COMPARISON_P (old
))
2997 if (COMPARISON_P (x
)
2998 && REVERSE_CONDEXEC_PREDICATES_P (x
, old
)
2999 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3001 if (GET_CODE (x
) == GET_CODE (old
)
3002 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3006 return gen_rtx_IOR (0, old
, x
);
3009 switch (GET_CODE (old
))
3012 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
3013 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
3014 if (op0
!= NULL
|| op1
!= NULL
)
3016 if (op0
== const0_rtx
)
3017 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
3018 if (op1
== const0_rtx
)
3019 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
3020 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3023 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
3024 else if (rtx_equal_p (x
, op0
))
3025 /* (x | A) | x ~ (x | A). */
3028 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3029 else if (rtx_equal_p (x
, op1
))
3030 /* (A | x) | x ~ (A | x). */
3032 return gen_rtx_IOR (0, op0
, op1
);
3036 return gen_rtx_IOR (0, old
, x
);
3039 op0
= ior_reg_cond (XEXP (old
, 0), x
, 0);
3040 op1
= ior_reg_cond (XEXP (old
, 1), x
, 0);
3041 if (op0
!= NULL
|| op1
!= NULL
)
3043 if (op0
== const1_rtx
)
3044 return op1
? op1
: gen_rtx_IOR (0, XEXP (old
, 1), x
);
3045 if (op1
== const1_rtx
)
3046 return op0
? op0
: gen_rtx_IOR (0, XEXP (old
, 0), x
);
3047 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3050 op0
= gen_rtx_IOR (0, XEXP (old
, 0), x
);
3051 else if (rtx_equal_p (x
, op0
))
3052 /* (x & A) | x ~ x. */
3055 op1
= gen_rtx_IOR (0, XEXP (old
, 1), x
);
3056 else if (rtx_equal_p (x
, op1
))
3057 /* (A & x) | x ~ x. */
3059 return gen_rtx_AND (0, op0
, op1
);
3063 return gen_rtx_IOR (0, old
, x
);
3066 op0
= and_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3068 return not_reg_cond (op0
);
3071 return gen_rtx_IOR (0, old
, x
);
3079 not_reg_cond (rtx x
)
3081 if (x
== const0_rtx
)
3083 else if (x
== const1_rtx
)
3085 if (GET_CODE (x
) == NOT
)
3087 if (COMPARISON_P (x
)
3088 && REG_P (XEXP (x
, 0)))
3090 gcc_assert (XEXP (x
, 1) == const0_rtx
);
3092 return gen_rtx_fmt_ee (reversed_comparison_code (x
, NULL
),
3093 VOIDmode
, XEXP (x
, 0), const0_rtx
);
3095 return gen_rtx_NOT (0, x
);
3099 and_reg_cond (rtx old
, rtx x
, int add
)
3103 if (COMPARISON_P (old
))
3105 if (COMPARISON_P (x
)
3106 && GET_CODE (x
) == reversed_comparison_code (old
, NULL
)
3107 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3109 if (GET_CODE (x
) == GET_CODE (old
)
3110 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (old
, 0)))
3114 return gen_rtx_AND (0, old
, x
);
3117 switch (GET_CODE (old
))
3120 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3121 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3122 if (op0
!= NULL
|| op1
!= NULL
)
3124 if (op0
== const0_rtx
)
3125 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3126 if (op1
== const0_rtx
)
3127 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3128 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3131 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3132 else if (rtx_equal_p (x
, op0
))
3133 /* (x | A) & x ~ x. */
3136 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3137 else if (rtx_equal_p (x
, op1
))
3138 /* (A | x) & x ~ x. */
3140 return gen_rtx_IOR (0, op0
, op1
);
3144 return gen_rtx_AND (0, old
, x
);
3147 op0
= and_reg_cond (XEXP (old
, 0), x
, 0);
3148 op1
= and_reg_cond (XEXP (old
, 1), x
, 0);
3149 if (op0
!= NULL
|| op1
!= NULL
)
3151 if (op0
== const1_rtx
)
3152 return op1
? op1
: gen_rtx_AND (0, XEXP (old
, 1), x
);
3153 if (op1
== const1_rtx
)
3154 return op0
? op0
: gen_rtx_AND (0, XEXP (old
, 0), x
);
3155 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3158 op0
= gen_rtx_AND (0, XEXP (old
, 0), x
);
3159 else if (rtx_equal_p (x
, op0
))
3160 /* (x & A) & x ~ (x & A). */
3163 op1
= gen_rtx_AND (0, XEXP (old
, 1), x
);
3164 else if (rtx_equal_p (x
, op1
))
3165 /* (A & x) & x ~ (A & x). */
3167 return gen_rtx_AND (0, op0
, op1
);
3171 return gen_rtx_AND (0, old
, x
);
3174 op0
= ior_reg_cond (XEXP (old
, 0), not_reg_cond (x
), 0);
3176 return not_reg_cond (op0
);
3179 return gen_rtx_AND (0, old
, x
);
3186 /* Given a condition X, remove references to reg REGNO and return the
3187 new condition. The removal will be done so that all conditions
3188 involving REGNO are considered to evaluate to false. This function
3189 is used when the value of REGNO changes. */
3192 elim_reg_cond (rtx x
, unsigned int regno
)
3196 if (COMPARISON_P (x
))
3198 if (REGNO (XEXP (x
, 0)) == regno
)
3203 switch (GET_CODE (x
))
3206 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3207 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3208 if (op0
== const0_rtx
|| op1
== const0_rtx
)
3210 if (op0
== const1_rtx
)
3212 if (op1
== const1_rtx
)
3214 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3216 return gen_rtx_AND (0, op0
, op1
);
3219 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3220 op1
= elim_reg_cond (XEXP (x
, 1), regno
);
3221 if (op0
== const1_rtx
|| op1
== const1_rtx
)
3223 if (op0
== const0_rtx
)
3225 if (op1
== const0_rtx
)
3227 if (op0
== XEXP (x
, 0) && op1
== XEXP (x
, 1))
3229 return gen_rtx_IOR (0, op0
, op1
);
3232 op0
= elim_reg_cond (XEXP (x
, 0), regno
);
3233 if (op0
== const0_rtx
)
3235 if (op0
== const1_rtx
)
3237 if (op0
!= XEXP (x
, 0))
3238 return not_reg_cond (op0
);
3245 #endif /* HAVE_conditional_execution */
3249 /* Try to substitute the auto-inc expression INC as the address inside
3250 MEM which occurs in INSN. Currently, the address of MEM is an expression
3251 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3252 that has a single set whose source is a PLUS of INCR_REG and something
3256 attempt_auto_inc (struct propagate_block_info
*pbi
, rtx inc
, rtx insn
,
3257 rtx mem
, rtx incr
, rtx incr_reg
)
3259 int regno
= REGNO (incr_reg
);
3260 rtx set
= single_set (incr
);
3261 rtx q
= SET_DEST (set
);
3262 rtx y
= SET_SRC (set
);
3263 int opnum
= XEXP (y
, 0) == incr_reg
? 0 : 1;
3266 /* Make sure this reg appears only once in this insn. */
3267 if (count_occurrences (PATTERN (insn
), incr_reg
, 1) != 1)
3270 if (dead_or_set_p (incr
, incr_reg
)
3271 /* Mustn't autoinc an eliminable register. */
3272 && (regno
>= FIRST_PSEUDO_REGISTER
3273 || ! TEST_HARD_REG_BIT (elim_reg_set
, regno
)))
3275 /* This is the simple case. Try to make the auto-inc. If
3276 we can't, we are done. Otherwise, we will do any
3277 needed updates below. */
3278 if (! validate_change (insn
, &XEXP (mem
, 0), inc
, 0))
3282 /* PREV_INSN used here to check the semi-open interval
3284 && ! reg_used_between_p (q
, PREV_INSN (insn
), incr
)
3285 /* We must also check for sets of q as q may be
3286 a call clobbered hard register and there may
3287 be a call between PREV_INSN (insn) and incr. */
3288 && ! reg_set_between_p (q
, PREV_INSN (insn
), incr
))
3290 /* We have *p followed sometime later by q = p+size.
3291 Both p and q must be live afterward,
3292 and q is not used between INSN and its assignment.
3293 Change it to q = p, ...*q..., q = q+size.
3294 Then fall into the usual case. */
3298 emit_move_insn (q
, incr_reg
);
3299 insns
= get_insns ();
3302 /* If we can't make the auto-inc, or can't make the
3303 replacement into Y, exit. There's no point in making
3304 the change below if we can't do the auto-inc and doing
3305 so is not correct in the pre-inc case. */
3308 validate_change (insn
, &XEXP (mem
, 0), inc
, 1);
3309 validate_change (incr
, &XEXP (y
, opnum
), q
, 1);
3310 if (! apply_change_group ())
3313 /* We now know we'll be doing this change, so emit the
3314 new insn(s) and do the updates. */
3315 emit_insn_before (insns
, insn
);
3317 if (BB_HEAD (pbi
->bb
) == insn
)
3318 BB_HEAD (pbi
->bb
) = insns
;
3320 /* INCR will become a NOTE and INSN won't contain a
3321 use of INCR_REG. If a use of INCR_REG was just placed in
3322 the insn before INSN, make that the next use.
3323 Otherwise, invalidate it. */
3324 if (NONJUMP_INSN_P (PREV_INSN (insn
))
3325 && GET_CODE (PATTERN (PREV_INSN (insn
))) == SET
3326 && SET_SRC (PATTERN (PREV_INSN (insn
))) == incr_reg
)
3327 pbi
->reg_next_use
[regno
] = PREV_INSN (insn
);
3329 pbi
->reg_next_use
[regno
] = 0;
3334 if ((pbi
->flags
& PROP_REG_INFO
)
3335 && !REGNO_REG_SET_P (pbi
->reg_live
, regno
))
3336 reg_deaths
[regno
] = pbi
->insn_num
;
3338 /* REGNO is now used in INCR which is below INSN, but
3339 it previously wasn't live here. If we don't mark
3340 it as live, we'll put a REG_DEAD note for it
3341 on this insn, which is incorrect. */
3342 SET_REGNO_REG_SET (pbi
->reg_live
, regno
);
3344 /* If there are any calls between INSN and INCR, show
3345 that REGNO now crosses them. */
3346 for (temp
= insn
; temp
!= incr
; temp
= NEXT_INSN (temp
))
3348 REG_N_CALLS_CROSSED (regno
)++;
3350 /* Invalidate alias info for Q since we just changed its value. */
3351 clear_reg_alias_info (q
);
3356 /* If we haven't returned, it means we were able to make the
3357 auto-inc, so update the status. First, record that this insn
3358 has an implicit side effect. */
3360 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, incr_reg
, REG_NOTES (insn
));
3362 /* Modify the old increment-insn to simply copy
3363 the already-incremented value of our register. */
3364 changed
= validate_change (incr
, &SET_SRC (set
), incr_reg
, 0);
3365 gcc_assert (changed
);
3367 /* If that makes it a no-op (copying the register into itself) delete
3368 it so it won't appear to be a "use" and a "set" of this
3370 if (REGNO (SET_DEST (set
)) == REGNO (incr_reg
))
3372 /* If the original source was dead, it's dead now. */
3375 while ((note
= find_reg_note (incr
, REG_DEAD
, NULL_RTX
)) != NULL_RTX
)
3377 remove_note (incr
, note
);
3378 if (XEXP (note
, 0) != incr_reg
)
3380 unsigned int regno
= REGNO (XEXP (note
, 0));
3382 if ((pbi
->flags
& PROP_REG_INFO
)
3383 && REGNO_REG_SET_P (pbi
->reg_live
, regno
))
3385 REG_LIVE_LENGTH (regno
) += pbi
->insn_num
- reg_deaths
[regno
];
3386 reg_deaths
[regno
] = 0;
3388 CLEAR_REGNO_REG_SET (pbi
->reg_live
, REGNO (XEXP (note
, 0)));
3392 SET_INSN_DELETED (incr
);
3395 if (regno
>= FIRST_PSEUDO_REGISTER
)
3397 /* Count an extra reference to the reg. When a reg is
3398 incremented, spilling it is worse, so we want to make
3399 that less likely. */
3400 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
3402 /* Count the increment as a setting of the register,
3403 even though it isn't a SET in rtl. */
3404 REG_N_SETS (regno
)++;
3408 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3412 find_auto_inc (struct propagate_block_info
*pbi
, rtx x
, rtx insn
)
3414 rtx addr
= XEXP (x
, 0);
3415 HOST_WIDE_INT offset
= 0;
3416 rtx set
, y
, incr
, inc_val
;
3418 int size
= GET_MODE_SIZE (GET_MODE (x
));
3423 /* Here we detect use of an index register which might be good for
3424 postincrement, postdecrement, preincrement, or predecrement. */
3426 if (GET_CODE (addr
) == PLUS
&& GET_CODE (XEXP (addr
, 1)) == CONST_INT
)
3427 offset
= INTVAL (XEXP (addr
, 1)), addr
= XEXP (addr
, 0);
3432 regno
= REGNO (addr
);
3434 /* Is the next use an increment that might make auto-increment? */
3435 incr
= pbi
->reg_next_use
[regno
];
3436 if (incr
== 0 || BLOCK_NUM (incr
) != BLOCK_NUM (insn
))
3438 set
= single_set (incr
);
3439 if (set
== 0 || GET_CODE (set
) != SET
)
3443 if (GET_CODE (y
) != PLUS
)
3446 if (REG_P (XEXP (y
, 0)) && REGNO (XEXP (y
, 0)) == REGNO (addr
))
3447 inc_val
= XEXP (y
, 1);
3448 else if (REG_P (XEXP (y
, 1)) && REGNO (XEXP (y
, 1)) == REGNO (addr
))
3449 inc_val
= XEXP (y
, 0);
3453 if (GET_CODE (inc_val
) == CONST_INT
)
3455 if (HAVE_POST_INCREMENT
3456 && (INTVAL (inc_val
) == size
&& offset
== 0))
3457 attempt_auto_inc (pbi
, gen_rtx_POST_INC (Pmode
, addr
), insn
, x
,
3459 else if (HAVE_POST_DECREMENT
3460 && (INTVAL (inc_val
) == -size
&& offset
== 0))
3461 attempt_auto_inc (pbi
, gen_rtx_POST_DEC (Pmode
, addr
), insn
, x
,
3463 else if (HAVE_PRE_INCREMENT
3464 && (INTVAL (inc_val
) == size
&& offset
== size
))
3465 attempt_auto_inc (pbi
, gen_rtx_PRE_INC (Pmode
, addr
), insn
, x
,
3467 else if (HAVE_PRE_DECREMENT
3468 && (INTVAL (inc_val
) == -size
&& offset
== -size
))
3469 attempt_auto_inc (pbi
, gen_rtx_PRE_DEC (Pmode
, addr
), insn
, x
,
3471 else if (HAVE_POST_MODIFY_DISP
&& offset
== 0)
3472 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3473 gen_rtx_PLUS (Pmode
,
3476 insn
, x
, incr
, addr
);
3477 else if (HAVE_PRE_MODIFY_DISP
&& offset
== INTVAL (inc_val
))
3478 attempt_auto_inc (pbi
, gen_rtx_PRE_MODIFY (Pmode
, addr
,
3479 gen_rtx_PLUS (Pmode
,
3482 insn
, x
, incr
, addr
);
3484 else if (REG_P (inc_val
)
3485 && ! reg_set_between_p (inc_val
, PREV_INSN (insn
),
3489 if (HAVE_POST_MODIFY_REG
&& offset
== 0)
3490 attempt_auto_inc (pbi
, gen_rtx_POST_MODIFY (Pmode
, addr
,
3491 gen_rtx_PLUS (Pmode
,
3494 insn
, x
, incr
, addr
);
3498 #endif /* AUTO_INC_DEC */
3501 mark_used_reg (struct propagate_block_info
*pbi
, rtx reg
,
3502 rtx cond ATTRIBUTE_UNUSED
, rtx insn
)
3504 unsigned int regno_first
, regno_last
, i
;
3505 int some_was_live
, some_was_dead
, some_not_set
;
3507 regno_last
= regno_first
= REGNO (reg
);
3508 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3509 regno_last
+= hard_regno_nregs
[regno_first
][GET_MODE (reg
)] - 1;
3511 /* Find out if any of this register is live after this instruction. */
3512 some_was_live
= some_was_dead
= 0;
3513 for (i
= regno_first
; i
<= regno_last
; ++i
)
3515 int needed_regno
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3516 some_was_live
|= needed_regno
;
3517 some_was_dead
|= ! needed_regno
;
3520 /* Find out if any of the register was set this insn. */
3522 for (i
= regno_first
; i
<= regno_last
; ++i
)
3523 some_not_set
|= ! REGNO_REG_SET_P (pbi
->new_set
, i
);
3525 if (pbi
->flags
& (PROP_LOG_LINKS
| PROP_AUTOINC
))
3527 /* Record where each reg is used, so when the reg is set we know
3528 the next insn that uses it. */
3529 pbi
->reg_next_use
[regno_first
] = insn
;
3532 if (pbi
->flags
& PROP_REG_INFO
)
3534 if (regno_first
< FIRST_PSEUDO_REGISTER
)
3536 /* If this is a register we are going to try to eliminate,
3537 don't mark it live here. If we are successful in
3538 eliminating it, it need not be live unless it is used for
3539 pseudos, in which case it will have been set live when it
3540 was allocated to the pseudos. If the register will not
3541 be eliminated, reload will set it live at that point.
3543 Otherwise, record that this function uses this register. */
3544 /* ??? The PPC backend tries to "eliminate" on the pic
3545 register to itself. This should be fixed. In the mean
3546 time, hack around it. */
3548 if (! (TEST_HARD_REG_BIT (elim_reg_set
, regno_first
)
3549 && (regno_first
== FRAME_POINTER_REGNUM
3550 || regno_first
== ARG_POINTER_REGNUM
)))
3551 for (i
= regno_first
; i
<= regno_last
; ++i
)
3552 regs_ever_live
[i
] = 1;
3556 /* Keep track of which basic block each reg appears in. */
3558 int blocknum
= pbi
->bb
->index
;
3559 if (REG_BASIC_BLOCK (regno_first
) == REG_BLOCK_UNKNOWN
)
3560 REG_BASIC_BLOCK (regno_first
) = blocknum
;
3561 else if (REG_BASIC_BLOCK (regno_first
) != blocknum
)
3562 REG_BASIC_BLOCK (regno_first
) = REG_BLOCK_GLOBAL
;
3564 /* Count (weighted) number of uses of each reg. */
3565 REG_FREQ (regno_first
) += REG_FREQ_FROM_BB (pbi
->bb
);
3566 REG_N_REFS (regno_first
)++;
3568 for (i
= regno_first
; i
<= regno_last
; ++i
)
3569 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
))
3571 gcc_assert (!reg_deaths
[i
]);
3572 reg_deaths
[i
] = pbi
->insn_num
;
3576 /* Record and count the insns in which a reg dies. If it is used in
3577 this insn and was dead below the insn then it dies in this insn.
3578 If it was set in this insn, we do not make a REG_DEAD note;
3579 likewise if we already made such a note. */
3580 if ((pbi
->flags
& (PROP_DEATH_NOTES
| PROP_REG_INFO
))
3584 /* Check for the case where the register dying partially
3585 overlaps the register set by this insn. */
3586 if (regno_first
!= regno_last
)
3587 for (i
= regno_first
; i
<= regno_last
; ++i
)
3588 some_was_live
|= REGNO_REG_SET_P (pbi
->new_set
, i
);
3590 /* If none of the words in X is needed, make a REG_DEAD note.
3591 Otherwise, we must make partial REG_DEAD notes. */
3592 if (! some_was_live
)
3594 if ((pbi
->flags
& PROP_DEATH_NOTES
)
3595 && ! find_regno_note (insn
, REG_DEAD
, regno_first
))
3597 = alloc_EXPR_LIST (REG_DEAD
, reg
, REG_NOTES (insn
));
3599 if (pbi
->flags
& PROP_REG_INFO
)
3600 REG_N_DEATHS (regno_first
)++;
3604 /* Don't make a REG_DEAD note for a part of a register
3605 that is set in the insn. */
3606 for (i
= regno_first
; i
<= regno_last
; ++i
)
3607 if (! REGNO_REG_SET_P (pbi
->reg_live
, i
)
3608 && ! dead_or_set_regno_p (insn
, i
))
3610 = alloc_EXPR_LIST (REG_DEAD
,
3616 /* Mark the register as being live. */
3617 for (i
= regno_first
; i
<= regno_last
; ++i
)
3619 #ifdef HAVE_conditional_execution
3620 int this_was_live
= REGNO_REG_SET_P (pbi
->reg_live
, i
);
3623 SET_REGNO_REG_SET (pbi
->reg_live
, i
);
3625 #ifdef HAVE_conditional_execution
3626 /* If this is a conditional use, record that fact. If it is later
3627 conditionally set, we'll know to kill the register. */
3628 if (cond
!= NULL_RTX
)
3630 splay_tree_node node
;
3631 struct reg_cond_life_info
*rcli
;
3636 node
= splay_tree_lookup (pbi
->reg_cond_dead
, i
);
3639 /* The register was unconditionally live previously.
3640 No need to do anything. */
3644 /* The register was conditionally live previously.
3645 Subtract the new life cond from the old death cond. */
3646 rcli
= (struct reg_cond_life_info
*) node
->value
;
3647 ncond
= rcli
->condition
;
3648 ncond
= and_reg_cond (ncond
, not_reg_cond (cond
), 1);
3650 /* If the register is now unconditionally live,
3651 remove the entry in the splay_tree. */
3652 if (ncond
== const0_rtx
)
3653 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3656 rcli
->condition
= ncond
;
3657 SET_REGNO_REG_SET (pbi
->reg_cond_reg
,
3658 REGNO (XEXP (cond
, 0)));
3664 /* The register was not previously live at all. Record
3665 the condition under which it is still dead. */
3666 rcli
= xmalloc (sizeof (*rcli
));
3667 rcli
->condition
= not_reg_cond (cond
);
3668 rcli
->stores
= const0_rtx
;
3669 rcli
->orig_condition
= const0_rtx
;
3670 splay_tree_insert (pbi
->reg_cond_dead
, i
,
3671 (splay_tree_value
) rcli
);
3673 SET_REGNO_REG_SET (pbi
->reg_cond_reg
, REGNO (XEXP (cond
, 0)));
3676 else if (this_was_live
)
3678 /* The register may have been conditionally live previously, but
3679 is now unconditionally live. Remove it from the conditionally
3680 dead list, so that a conditional set won't cause us to think
3682 splay_tree_remove (pbi
->reg_cond_dead
, i
);
3688 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3689 This is done assuming the registers needed from X are those that
3690 have 1-bits in PBI->REG_LIVE.
3692 INSN is the containing instruction. If INSN is dead, this function
3696 mark_used_regs (struct propagate_block_info
*pbi
, rtx x
, rtx cond
, rtx insn
)
3700 int flags
= pbi
->flags
;
3705 code
= GET_CODE (x
);
3726 /* If we are clobbering a MEM, mark any registers inside the address
3728 if (MEM_P (XEXP (x
, 0)))
3729 mark_used_regs (pbi
, XEXP (XEXP (x
, 0), 0), cond
, insn
);
3733 /* Don't bother watching stores to mems if this is not the
3734 final pass. We'll not be deleting dead stores this round. */
3735 if (optimize
&& (flags
& PROP_SCAN_DEAD_STORES
))
3737 /* Invalidate the data for the last MEM stored, but only if MEM is
3738 something that can be stored into. */
3739 if (GET_CODE (XEXP (x
, 0)) == SYMBOL_REF
3740 && CONSTANT_POOL_ADDRESS_P (XEXP (x
, 0)))
3741 /* Needn't clear the memory set list. */
3745 rtx temp
= pbi
->mem_set_list
;
3746 rtx prev
= NULL_RTX
;
3751 next
= XEXP (temp
, 1);
3752 if (anti_dependence (XEXP (temp
, 0), x
))
3754 /* Splice temp out of the list. */
3756 XEXP (prev
, 1) = next
;
3758 pbi
->mem_set_list
= next
;
3759 free_EXPR_LIST_node (temp
);
3760 pbi
->mem_set_list_len
--;
3768 /* If the memory reference had embedded side effects (autoincrement
3769 address modes. Then we may need to kill some entries on the
3772 for_each_rtx (&PATTERN (insn
), invalidate_mems_from_autoinc
, pbi
);
3776 if (flags
& PROP_AUTOINC
)
3777 find_auto_inc (pbi
, x
, insn
);
3782 #ifdef CANNOT_CHANGE_MODE_CLASS
3783 if (flags
& PROP_REG_INFO
)
3784 record_subregs_of_mode (x
);
3787 /* While we're here, optimize this case. */
3794 /* See a register other than being set => mark it as needed. */
3795 mark_used_reg (pbi
, x
, cond
, insn
);
3800 rtx testreg
= SET_DEST (x
);
3803 /* If storing into MEM, don't show it as being used. But do
3804 show the address as being used. */
3805 if (MEM_P (testreg
))
3808 if (flags
& PROP_AUTOINC
)
3809 find_auto_inc (pbi
, testreg
, insn
);
3811 mark_used_regs (pbi
, XEXP (testreg
, 0), cond
, insn
);
3812 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3816 /* Storing in STRICT_LOW_PART is like storing in a reg
3817 in that this SET might be dead, so ignore it in TESTREG.
3818 but in some other ways it is like using the reg.
3820 Storing in a SUBREG or a bit field is like storing the entire
3821 register in that if the register's value is not used
3822 then this SET is not needed. */
3823 while (GET_CODE (testreg
) == STRICT_LOW_PART
3824 || GET_CODE (testreg
) == ZERO_EXTRACT
3825 || GET_CODE (testreg
) == SIGN_EXTRACT
3826 || GET_CODE (testreg
) == SUBREG
)
3828 #ifdef CANNOT_CHANGE_MODE_CLASS
3829 if ((flags
& PROP_REG_INFO
) && GET_CODE (testreg
) == SUBREG
)
3830 record_subregs_of_mode (testreg
);
3833 /* Modifying a single register in an alternate mode
3834 does not use any of the old value. But these other
3835 ways of storing in a register do use the old value. */
3836 if (GET_CODE (testreg
) == SUBREG
3837 && !((REG_BYTES (SUBREG_REG (testreg
))
3838 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
3839 > (REG_BYTES (testreg
)
3840 + UNITS_PER_WORD
- 1) / UNITS_PER_WORD
))
3845 testreg
= XEXP (testreg
, 0);
3848 /* If this is a store into a register or group of registers,
3849 recursively scan the value being stored. */
3851 if ((GET_CODE (testreg
) == PARALLEL
3852 && GET_MODE (testreg
) == BLKmode
)
3854 && (regno
= REGNO (testreg
),
3855 ! (regno
== FRAME_POINTER_REGNUM
3856 && (! reload_completed
|| frame_pointer_needed
)))
3857 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3858 && ! (regno
== HARD_FRAME_POINTER_REGNUM
3859 && (! reload_completed
|| frame_pointer_needed
))
3861 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3862 && ! (regno
== ARG_POINTER_REGNUM
&& fixed_regs
[regno
])
3867 mark_used_regs (pbi
, SET_DEST (x
), cond
, insn
);
3868 mark_used_regs (pbi
, SET_SRC (x
), cond
, insn
);
3875 case UNSPEC_VOLATILE
:
3879 /* Traditional and volatile asm instructions must be considered to use
3880 and clobber all hard registers, all pseudo-registers and all of
3881 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3883 Consider for instance a volatile asm that changes the fpu rounding
3884 mode. An insn should not be moved across this even if it only uses
3885 pseudo-regs because it might give an incorrectly rounded result.
3887 ?!? Unfortunately, marking all hard registers as live causes massive
3888 problems for the register allocator and marking all pseudos as live
3889 creates mountains of uninitialized variable warnings.
3891 So for now, just clear the memory set list and mark any regs
3892 we can find in ASM_OPERANDS as used. */
3893 if (code
!= ASM_OPERANDS
|| MEM_VOLATILE_P (x
))
3895 free_EXPR_LIST_list (&pbi
->mem_set_list
);
3896 pbi
->mem_set_list_len
= 0;
3899 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3900 We can not just fall through here since then we would be confused
3901 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3902 traditional asms unlike their normal usage. */
3903 if (code
== ASM_OPERANDS
)
3907 for (j
= 0; j
< ASM_OPERANDS_INPUT_LENGTH (x
); j
++)
3908 mark_used_regs (pbi
, ASM_OPERANDS_INPUT (x
, j
), cond
, insn
);
3916 mark_used_regs (pbi
, COND_EXEC_TEST (x
), NULL_RTX
, insn
);
3918 cond
= COND_EXEC_TEST (x
);
3919 x
= COND_EXEC_CODE (x
);
3926 /* Recursively scan the operands of this expression. */
3929 const char * const fmt
= GET_RTX_FORMAT (code
);
3932 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3936 /* Tail recursive case: save a function call level. */
3942 mark_used_regs (pbi
, XEXP (x
, i
), cond
, insn
);
3944 else if (fmt
[i
] == 'E')
3947 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3948 mark_used_regs (pbi
, XVECEXP (x
, i
, j
), cond
, insn
);
3957 try_pre_increment_1 (struct propagate_block_info
*pbi
, rtx insn
)
3959 /* Find the next use of this reg. If in same basic block,
3960 make it do pre-increment or pre-decrement if appropriate. */
3961 rtx x
= single_set (insn
);
3962 HOST_WIDE_INT amount
= ((GET_CODE (SET_SRC (x
)) == PLUS
? 1 : -1)
3963 * INTVAL (XEXP (SET_SRC (x
), 1)));
3964 int regno
= REGNO (SET_DEST (x
));
3965 rtx y
= pbi
->reg_next_use
[regno
];
3967 && SET_DEST (x
) != stack_pointer_rtx
3968 && BLOCK_NUM (y
) == BLOCK_NUM (insn
)
3969 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3970 mode would be better. */
3971 && ! dead_or_set_p (y
, SET_DEST (x
))
3972 && try_pre_increment (y
, SET_DEST (x
), amount
))
3974 /* We have found a suitable auto-increment and already changed
3975 insn Y to do it. So flush this increment instruction. */
3976 propagate_block_delete_insn (insn
);
3978 /* Count a reference to this reg for the increment insn we are
3979 deleting. When a reg is incremented, spilling it is worse,
3980 so we want to make that less likely. */
3981 if (regno
>= FIRST_PSEUDO_REGISTER
)
3983 REG_FREQ (regno
) += REG_FREQ_FROM_BB (pbi
->bb
);
3984 REG_N_SETS (regno
)++;
3987 /* Flush any remembered memories depending on the value of
3988 the incremented register. */
3989 invalidate_mems_from_set (pbi
, SET_DEST (x
));
3996 /* Try to change INSN so that it does pre-increment or pre-decrement
3997 addressing on register REG in order to add AMOUNT to REG.
3998 AMOUNT is negative for pre-decrement.
3999 Returns 1 if the change could be made.
4000 This checks all about the validity of the result of modifying INSN. */
4003 try_pre_increment (rtx insn
, rtx reg
, HOST_WIDE_INT amount
)
4007 /* Nonzero if we can try to make a pre-increment or pre-decrement.
4008 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
4010 /* Nonzero if we can try to make a post-increment or post-decrement.
4011 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
4012 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
4013 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
4016 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
4019 /* From the sign of increment, see which possibilities are conceivable
4020 on this target machine. */
4021 if (HAVE_PRE_INCREMENT
&& amount
> 0)
4023 if (HAVE_POST_INCREMENT
&& amount
> 0)
4026 if (HAVE_PRE_DECREMENT
&& amount
< 0)
4028 if (HAVE_POST_DECREMENT
&& amount
< 0)
4031 if (! (pre_ok
|| post_ok
))
4034 /* It is not safe to add a side effect to a jump insn
4035 because if the incremented register is spilled and must be reloaded
4036 there would be no way to store the incremented value back in memory. */
4043 use
= find_use_as_address (PATTERN (insn
), reg
, 0);
4044 if (post_ok
&& (use
== 0 || use
== (rtx
) (size_t) 1))
4046 use
= find_use_as_address (PATTERN (insn
), reg
, -amount
);
4050 if (use
== 0 || use
== (rtx
) (size_t) 1)
4053 if (GET_MODE_SIZE (GET_MODE (use
)) != (amount
> 0 ? amount
: - amount
))
4056 /* See if this combination of instruction and addressing mode exists. */
4057 if (! validate_change (insn
, &XEXP (use
, 0),
4058 gen_rtx_fmt_e (amount
> 0
4059 ? (do_post
? POST_INC
: PRE_INC
)
4060 : (do_post
? POST_DEC
: PRE_DEC
),
4064 /* Record that this insn now has an implicit side effect on X. */
4065 REG_NOTES (insn
) = alloc_EXPR_LIST (REG_INC
, reg
, REG_NOTES (insn
));
4069 #endif /* AUTO_INC_DEC */
4071 /* Find the place in the rtx X where REG is used as a memory address.
4072 Return the MEM rtx that so uses it.
4073 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4074 (plus REG (const_int PLUSCONST)).
4076 If such an address does not appear, return 0.
4077 If REG appears more than once, or is used other than in such an address,
4081 find_use_as_address (rtx x
, rtx reg
, HOST_WIDE_INT plusconst
)
4083 enum rtx_code code
= GET_CODE (x
);
4084 const char * const fmt
= GET_RTX_FORMAT (code
);
4089 if (code
== MEM
&& XEXP (x
, 0) == reg
&& plusconst
== 0)
4092 if (code
== MEM
&& GET_CODE (XEXP (x
, 0)) == PLUS
4093 && XEXP (XEXP (x
, 0), 0) == reg
4094 && GET_CODE (XEXP (XEXP (x
, 0), 1)) == CONST_INT
4095 && INTVAL (XEXP (XEXP (x
, 0), 1)) == plusconst
)
4098 if (code
== SIGN_EXTRACT
|| code
== ZERO_EXTRACT
)
4100 /* If REG occurs inside a MEM used in a bit-field reference,
4101 that is unacceptable. */
4102 if (find_use_as_address (XEXP (x
, 0), reg
, 0) != 0)
4103 return (rtx
) (size_t) 1;
4107 return (rtx
) (size_t) 1;
4109 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4113 tem
= find_use_as_address (XEXP (x
, i
), reg
, plusconst
);
4117 return (rtx
) (size_t) 1;
4119 else if (fmt
[i
] == 'E')
4122 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4124 tem
= find_use_as_address (XVECEXP (x
, i
, j
), reg
, plusconst
);
4128 return (rtx
) (size_t) 1;
4136 /* Write information about registers and basic blocks into FILE.
4137 This is part of making a debugging dump. */
4140 dump_regset (regset r
, FILE *outf
)
4143 reg_set_iterator rsi
;
4147 fputs (" (nil)", outf
);
4151 EXECUTE_IF_SET_IN_REG_SET (r
, 0, i
, rsi
)
4153 fprintf (outf
, " %d", i
);
4154 if (i
< FIRST_PSEUDO_REGISTER
)
4155 fprintf (outf
, " [%s]",
4160 /* Print a human-readable representation of R on the standard error
4161 stream. This function is designed to be used from within the
4165 debug_regset (regset r
)
4167 dump_regset (r
, stderr
);
4168 putc ('\n', stderr
);
4171 /* Recompute register set/reference counts immediately prior to register
4174 This avoids problems with set/reference counts changing to/from values
4175 which have special meanings to the register allocators.
4177 Additionally, the reference counts are the primary component used by the
4178 register allocators to prioritize pseudos for allocation to hard regs.
4179 More accurate reference counts generally lead to better register allocation.
4181 F is the first insn to be scanned.
4183 LOOP_STEP denotes how much loop_depth should be incremented per
4184 loop nesting level in order to increase the ref count more for
4185 references in a loop.
4187 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4188 possibly other information which is used by the register allocators. */
4191 recompute_reg_usage (rtx f ATTRIBUTE_UNUSED
, int loop_step ATTRIBUTE_UNUSED
)
4193 allocate_reg_life_data ();
4194 /* distribute_notes in combiner fails to convert some of the REG_UNUSED notes
4195 to REG_DEAD notes. This causes CHECK_DEAD_NOTES in sched1 to abort. To
4196 solve this update the DEATH_NOTES here. */
4197 update_life_info (NULL
, UPDATE_LIFE_LOCAL
, PROP_REG_INFO
| PROP_DEATH_NOTES
);
4200 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4201 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4202 of the number of registers that died. */
4205 count_or_remove_death_notes (sbitmap blocks
, int kill
)
4211 /* This used to be a loop over all the blocks with a membership test
4212 inside the loop. That can be amazingly expensive on a large CFG
4213 when only a small number of bits are set in BLOCKs (for example,
4214 the calls from the scheduler typically have very few bits set).
4216 For extra credit, someone should convert BLOCKS to a bitmap rather
4220 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4222 count
+= count_or_remove_death_notes_bb (BASIC_BLOCK (i
), kill
);
4229 count
+= count_or_remove_death_notes_bb (bb
, kill
);
4236 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from basic
4237 block BB. Returns a count of the number of registers that died. */
4240 count_or_remove_death_notes_bb (basic_block bb
, int kill
)
4245 for (insn
= BB_HEAD (bb
); ; insn
= NEXT_INSN (insn
))
4249 rtx
*pprev
= ®_NOTES (insn
);
4254 switch (REG_NOTE_KIND (link
))
4257 if (REG_P (XEXP (link
, 0)))
4259 rtx reg
= XEXP (link
, 0);
4262 if (REGNO (reg
) >= FIRST_PSEUDO_REGISTER
)
4265 n
= hard_regno_nregs
[REGNO (reg
)][GET_MODE (reg
)];
4274 rtx next
= XEXP (link
, 1);
4275 free_EXPR_LIST_node (link
);
4276 *pprev
= link
= next
;
4282 pprev
= &XEXP (link
, 1);
4289 if (insn
== BB_END (bb
))
4296 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4297 if blocks is NULL. */
4300 clear_log_links (sbitmap blocks
)
4307 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
4309 free_INSN_LIST_list (&LOG_LINKS (insn
));
4312 EXECUTE_IF_SET_IN_SBITMAP (blocks
, 0, i
,
4314 basic_block bb
= BASIC_BLOCK (i
);
4316 for (insn
= BB_HEAD (bb
); insn
!= NEXT_INSN (BB_END (bb
));
4317 insn
= NEXT_INSN (insn
))
4319 free_INSN_LIST_list (&LOG_LINKS (insn
));
4323 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4324 correspond to the hard registers, if any, set in that map. This
4325 could be done far more efficiently by having all sorts of special-cases
4326 with moving single words, but probably isn't worth the trouble. */
4329 reg_set_to_hard_reg_set (HARD_REG_SET
*to
, bitmap from
)
4334 EXECUTE_IF_SET_IN_BITMAP (from
, 0, i
, bi
)
4336 if (i
>= FIRST_PSEUDO_REGISTER
)
4338 SET_HARD_REG_BIT (*to
, i
);