1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001 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
126 #include "hard-reg-set.h"
127 #include "basic-block.h"
128 #include "insn-config.h"
132 #include "function.h"
141 #include "splay-tree.h"
143 #define obstack_chunk_alloc xmalloc
144 #define obstack_chunk_free free
146 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
147 the stack pointer does not matter. The value is tested only in
148 functions that have frame pointers.
149 No definition is equivalent to always zero. */
150 #ifndef EXIT_IGNORE_STACK
151 #define EXIT_IGNORE_STACK 0
154 #ifndef HAVE_epilogue
155 #define HAVE_epilogue 0
157 #ifndef HAVE_prologue
158 #define HAVE_prologue 0
160 #ifndef HAVE_sibcall_epilogue
161 #define HAVE_sibcall_epilogue 0
165 #define LOCAL_REGNO(REGNO) 0
167 #ifndef EPILOGUE_USES
168 #define EPILOGUE_USES(REGNO) 0
171 #ifdef HAVE_conditional_execution
172 #ifndef REVERSE_CONDEXEC_PREDICATES_P
173 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y))
177 /* Nonzero if the second flow pass has completed. */
180 /* Maximum register number used in this function, plus one. */
184 /* Indexed by n, giving various register information */
186 varray_type reg_n_info;
188 /* Size of a regset for the current function,
189 in (1) bytes and (2) elements. */
194 /* Regset of regs live when calls to `setjmp'-like functions happen. */
195 /* ??? Does this exist only for the setjmp-clobbered warning message? */
197 regset regs_live_at_setjmp;
199 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
200 that have to go in the same hard reg.
201 The first two regs in the list are a pair, and the next two
202 are another pair, etc. */
205 /* Callback that determines if it's ok for a function to have no
206 noreturn attribute. */
207 int (*lang_missing_noreturn_ok_p) PARAMS ((tree));
209 /* Set of registers that may be eliminable. These are handled specially
210 in updating regs_ever_live. */
212 static HARD_REG_SET elim_reg_set;
214 /* Holds information for tracking conditional register life information. */
215 struct reg_cond_life_info
217 /* A boolean expression of conditions under which a register is dead. */
219 /* Conditions under which a register is dead at the basic block end. */
222 /* A boolean expression of conditions under which a register has been
226 /* ??? Could store mask of bytes that are dead, so that we could finally
227 track lifetimes of multi-word registers accessed via subregs. */
230 /* For use in communicating between propagate_block and its subroutines.
231 Holds all information needed to compute life and def-use information. */
233 struct propagate_block_info
235 /* The basic block we're considering. */
238 /* Bit N is set if register N is conditionally or unconditionally live. */
241 /* Bit N is set if register N is set this insn. */
244 /* Element N is the next insn that uses (hard or pseudo) register N
245 within the current basic block; or zero, if there is no such insn. */
248 /* Contains a list of all the MEMs we are tracking for dead store
252 /* If non-null, record the set of registers set unconditionally in the
256 /* If non-null, record the set of registers set conditionally in the
258 regset cond_local_set;
260 #ifdef HAVE_conditional_execution
261 /* Indexed by register number, holds a reg_cond_life_info for each
262 register that is not unconditionally live or dead. */
263 splay_tree reg_cond_dead;
265 /* Bit N is set if register N is in an expression in reg_cond_dead. */
269 /* The length of mem_set_list. */
270 int mem_set_list_len;
272 /* Non-zero if the value of CC0 is live. */
275 /* Flags controling the set of information propagate_block collects. */
279 /* Maximum length of pbi->mem_set_list before we start dropping
280 new elements on the floor. */
281 #define MAX_MEM_SET_LIST_LEN 100
283 /* Have print_rtl_and_abort give the same information that fancy_abort
285 #define print_rtl_and_abort() \
286 print_rtl_and_abort_fcn (__FILE__, __LINE__, __FUNCTION__)
288 /* Forward declarations */
289 static int verify_wide_reg_1 PARAMS ((rtx *, void *));
290 static void verify_wide_reg PARAMS ((int, rtx, rtx));
291 static void verify_local_live_at_start PARAMS ((regset, basic_block));
292 static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *));
293 static void notice_stack_pointer_modification PARAMS ((rtx));
294 static void mark_reg PARAMS ((rtx, void *));
295 static void mark_regs_live_at_end PARAMS ((regset));
296 static int set_phi_alternative_reg PARAMS ((rtx, int, int, void *));
297 static void calculate_global_regs_live PARAMS ((sbitmap, sbitmap, int));
298 static void propagate_block_delete_insn PARAMS ((basic_block, rtx));
299 static rtx propagate_block_delete_libcall PARAMS ((rtx, rtx));
300 static int insn_dead_p PARAMS ((struct propagate_block_info *,
302 static int libcall_dead_p PARAMS ((struct propagate_block_info *,
304 static void mark_set_regs PARAMS ((struct propagate_block_info *,
306 static void mark_set_1 PARAMS ((struct propagate_block_info *,
307 enum rtx_code, rtx, rtx,
309 #ifdef HAVE_conditional_execution
310 static int mark_regno_cond_dead PARAMS ((struct propagate_block_info *,
312 static void free_reg_cond_life_info PARAMS ((splay_tree_value));
313 static int flush_reg_cond_reg_1 PARAMS ((splay_tree_node, void *));
314 static void flush_reg_cond_reg PARAMS ((struct propagate_block_info *,
316 static rtx elim_reg_cond PARAMS ((rtx, unsigned int));
317 static rtx ior_reg_cond PARAMS ((rtx, rtx, int));
318 static rtx not_reg_cond PARAMS ((rtx));
319 static rtx and_reg_cond PARAMS ((rtx, rtx, int));
322 static void attempt_auto_inc PARAMS ((struct propagate_block_info *,
323 rtx, rtx, rtx, rtx, rtx));
324 static void find_auto_inc PARAMS ((struct propagate_block_info *,
326 static int try_pre_increment_1 PARAMS ((struct propagate_block_info *,
328 static int try_pre_increment PARAMS ((rtx, rtx, HOST_WIDE_INT));
330 static void mark_used_reg PARAMS ((struct propagate_block_info *,
332 static void mark_used_regs PARAMS ((struct propagate_block_info *,
334 void dump_flow_info PARAMS ((FILE *));
335 void debug_flow_info PARAMS ((void));
336 static void print_rtl_and_abort_fcn PARAMS ((const char *, int,
340 static void add_to_mem_set_list PARAMS ((struct propagate_block_info *,
342 static void invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *,
344 static void invalidate_mems_from_set PARAMS ((struct propagate_block_info *,
346 static void delete_dead_jumptables PARAMS ((void));
347 static void clear_log_links PARAMS ((sbitmap));
351 check_function_return_warnings ()
353 if (warn_missing_noreturn
354 && !TREE_THIS_VOLATILE (cfun->decl)
355 && EXIT_BLOCK_PTR->pred == NULL
356 && (lang_missing_noreturn_ok_p
357 && !lang_missing_noreturn_ok_p (cfun->decl)))
358 warning ("function might be possible candidate for attribute `noreturn'");
360 /* If we have a path to EXIT, then we do return. */
361 if (TREE_THIS_VOLATILE (cfun->decl)
362 && EXIT_BLOCK_PTR->pred != NULL)
363 warning ("`noreturn' function does return");
365 /* If the clobber_return_insn appears in some basic block, then we
366 do reach the end without returning a value. */
367 else if (warn_return_type
368 && cfun->x_clobber_return_insn != NULL
369 && EXIT_BLOCK_PTR->pred != NULL)
371 int max_uid = get_max_uid ();
373 /* If clobber_return_insn was excised by jump1, then renumber_insns
374 can make max_uid smaller than the number still recorded in our rtx.
375 That's fine, since this is a quick way of verifying that the insn
376 is no longer in the chain. */
377 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
379 /* Recompute insn->block mapping, since the initial mapping is
380 set before we delete unreachable blocks. */
381 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL)
382 warning ("control reaches end of non-void function");
387 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
388 note associated with the BLOCK. */
391 first_insn_after_basic_block_note (block)
396 /* Get the first instruction in the block. */
399 if (insn == NULL_RTX)
401 if (GET_CODE (insn) == CODE_LABEL)
402 insn = NEXT_INSN (insn);
403 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
406 return NEXT_INSN (insn);
409 /* Perform data flow analysis.
410 F is the first insn of the function; FLAGS is a set of PROP_* flags
411 to be used in accumulating flow info. */
414 life_analysis (f, file, flags)
419 #ifdef ELIMINABLE_REGS
421 static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS;
424 /* Record which registers will be eliminated. We use this in
427 CLEAR_HARD_REG_SET (elim_reg_set);
429 #ifdef ELIMINABLE_REGS
430 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
431 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
433 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
437 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES);
439 /* The post-reload life analysis have (on a global basis) the same
440 registers live as was computed by reload itself. elimination
441 Otherwise offsets and such may be incorrect.
443 Reload will make some registers as live even though they do not
446 We don't want to create new auto-incs after reload, since they
447 are unlikely to be useful and can cause problems with shared
449 if (reload_completed)
450 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
452 /* We want alias analysis information for local dead store elimination. */
453 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
454 init_alias_analysis ();
456 /* Always remove no-op moves. Do this before other processing so
457 that we don't have to keep re-scanning them. */
458 delete_noop_moves (f);
459 purge_all_dead_edges (false);
461 /* Some targets can emit simpler epilogues if they know that sp was
462 not ever modified during the function. After reload, of course,
463 we've already emitted the epilogue so there's no sense searching. */
464 if (! reload_completed)
465 notice_stack_pointer_modification (f);
467 /* Allocate and zero out data structures that will record the
468 data from lifetime analysis. */
469 allocate_reg_life_data ();
470 allocate_bb_life_data ();
472 /* Find the set of registers live on function exit. */
473 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
475 /* "Update" life info from zero. It'd be nice to begin the
476 relaxation with just the exit and noreturn blocks, but that set
477 is not immediately handy. */
479 if (flags & PROP_REG_INFO)
480 memset (regs_ever_live, 0, sizeof (regs_ever_live));
481 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
484 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
485 end_alias_analysis ();
488 dump_flow_info (file);
490 free_basic_block_vars (1);
492 #ifdef ENABLE_CHECKING
496 /* Search for any REG_LABEL notes which reference deleted labels. */
497 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
499 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
501 if (inote && GET_CODE (inote) == NOTE_INSN_DELETED_LABEL)
506 /* Removing dead insns should've made jumptables really dead. */
507 delete_dead_jumptables ();
510 /* A subroutine of verify_wide_reg, called through for_each_rtx.
511 Search for REGNO. If found, abort if it is not wider than word_mode. */
514 verify_wide_reg_1 (px, pregno)
519 unsigned int regno = *(int *) pregno;
521 if (GET_CODE (x) == REG && REGNO (x) == regno)
523 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
530 /* A subroutine of verify_local_live_at_start. Search through insns
531 between HEAD and END looking for register REGNO. */
534 verify_wide_reg (regno, head, end)
541 && for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no))
545 head = NEXT_INSN (head);
548 /* We didn't find the register at all. Something's way screwy. */
550 fprintf (rtl_dump_file, "Aborting in verify_wide_reg; reg %d\n", regno);
551 print_rtl_and_abort ();
554 /* A subroutine of update_life_info. Verify that there are no untoward
555 changes in live_at_start during a local update. */
558 verify_local_live_at_start (new_live_at_start, bb)
559 regset new_live_at_start;
562 if (reload_completed)
564 /* After reload, there are no pseudos, nor subregs of multi-word
565 registers. The regsets should exactly match. */
566 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
570 fprintf (rtl_dump_file,
571 "live_at_start mismatch in bb %d, aborting\n",
573 debug_bitmap_file (rtl_dump_file, bb->global_live_at_start);
574 debug_bitmap_file (rtl_dump_file, new_live_at_start);
576 print_rtl_and_abort ();
583 /* Find the set of changed registers. */
584 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
586 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
588 /* No registers should die. */
589 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
592 fprintf (rtl_dump_file,
593 "Register %d died unexpectedly in block %d\n", i,
595 print_rtl_and_abort ();
598 /* Verify that the now-live register is wider than word_mode. */
599 verify_wide_reg (i, bb->head, bb->end);
604 /* Updates life information starting with the basic blocks set in BLOCKS.
605 If BLOCKS is null, consider it to be the universal set.
607 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
608 we are only expecting local modifications to basic blocks. If we find
609 extra registers live at the beginning of a block, then we either killed
610 useful data, or we have a broken split that wants data not provided.
611 If we find registers removed from live_at_start, that means we have
612 a broken peephole that is killing a register it shouldn't.
614 ??? This is not true in one situation -- when a pre-reload splitter
615 generates subregs of a multi-word pseudo, current life analysis will
616 lose the kill. So we _can_ have a pseudo go live. How irritating.
618 Including PROP_REG_INFO does not properly refresh regs_ever_live
619 unless the caller resets it to zero. */
622 update_life_info (blocks, extent, prop_flags)
624 enum update_life_extent extent;
628 regset_head tmp_head;
631 tmp = INITIALIZE_REG_SET (tmp_head);
633 timevar_push ((extent == UPDATE_LIFE_LOCAL || blocks)
634 ? TV_LIFE_UPDATE : TV_LIFE);
636 /* Changes to the CFG are only allowed when
637 doing a global update for the entire CFG. */
638 if ((prop_flags & PROP_ALLOW_CFG_CHANGES)
639 && (extent == UPDATE_LIFE_LOCAL || blocks))
642 /* Clear log links in case we are asked to (re)compute them. */
643 if (prop_flags & PROP_LOG_LINKS)
644 clear_log_links (blocks);
646 /* For a global update, we go through the relaxation process again. */
647 if (extent != UPDATE_LIFE_LOCAL)
653 calculate_global_regs_live (blocks, blocks,
654 prop_flags & (PROP_SCAN_DEAD_CODE
655 | PROP_ALLOW_CFG_CHANGES));
657 if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
658 != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
661 /* Removing dead code may allow the CFG to be simplified which
662 in turn may allow for further dead code detection / removal. */
663 for (i = n_basic_blocks - 1; i >= 0; --i)
665 basic_block bb = BASIC_BLOCK (i);
667 COPY_REG_SET (tmp, bb->global_live_at_end);
668 changed |= propagate_block (bb, tmp, NULL, NULL,
669 prop_flags & (PROP_SCAN_DEAD_CODE
670 | PROP_KILL_DEAD_CODE));
673 if (! changed || ! cleanup_cfg (CLEANUP_EXPENSIVE))
677 /* If asked, remove notes from the blocks we'll update. */
678 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
679 count_or_remove_death_notes (blocks, 1);
684 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
686 basic_block bb = BASIC_BLOCK (i);
688 COPY_REG_SET (tmp, bb->global_live_at_end);
689 propagate_block (bb, tmp, NULL, NULL, prop_flags);
691 if (extent == UPDATE_LIFE_LOCAL)
692 verify_local_live_at_start (tmp, bb);
697 for (i = n_basic_blocks - 1; i >= 0; --i)
699 basic_block bb = BASIC_BLOCK (i);
701 COPY_REG_SET (tmp, bb->global_live_at_end);
702 propagate_block (bb, tmp, NULL, NULL, prop_flags);
704 if (extent == UPDATE_LIFE_LOCAL)
705 verify_local_live_at_start (tmp, bb);
711 if (prop_flags & PROP_REG_INFO)
713 /* The only pseudos that are live at the beginning of the function
714 are those that were not set anywhere in the function. local-alloc
715 doesn't know how to handle these correctly, so mark them as not
716 local to any one basic block. */
717 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
718 FIRST_PSEUDO_REGISTER, i,
719 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
721 /* We have a problem with any pseudoreg that lives across the setjmp.
722 ANSI says that if a user variable does not change in value between
723 the setjmp and the longjmp, then the longjmp preserves it. This
724 includes longjmp from a place where the pseudo appears dead.
725 (In principle, the value still exists if it is in scope.)
726 If the pseudo goes in a hard reg, some other value may occupy
727 that hard reg where this pseudo is dead, thus clobbering the pseudo.
728 Conclusion: such a pseudo must not go in a hard reg. */
729 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
730 FIRST_PSEUDO_REGISTER, i,
732 if (regno_reg_rtx[i] != 0)
734 REG_LIVE_LENGTH (i) = -1;
735 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
739 timevar_pop ((extent == UPDATE_LIFE_LOCAL || blocks)
740 ? TV_LIFE_UPDATE : TV_LIFE);
743 /* Free the variables allocated by find_basic_blocks.
745 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
748 free_basic_block_vars (keep_head_end_p)
751 if (! keep_head_end_p)
753 if (basic_block_info)
756 VARRAY_FREE (basic_block_info);
760 ENTRY_BLOCK_PTR->aux = NULL;
761 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
762 EXIT_BLOCK_PTR->aux = NULL;
763 EXIT_BLOCK_PTR->global_live_at_start = NULL;
767 /* Delete any insns that copy a register to itself. */
770 delete_noop_moves (f)
771 rtx f ATTRIBUTE_UNUSED;
777 for (i = 0; i < n_basic_blocks; i++)
779 bb = BASIC_BLOCK (i);
780 for (insn = bb->head; insn != NEXT_INSN (bb->end); insn = next)
782 next = NEXT_INSN (insn);
783 if (INSN_P (insn) && noop_move_p (insn))
787 /* If we're about to remove the first insn of a libcall
788 then move the libcall note to the next real insn and
789 update the retval note. */
790 if ((note = find_reg_note (insn, REG_LIBCALL, NULL_RTX))
791 && XEXP (note, 0) != insn)
793 rtx new_libcall_insn = next_real_insn (insn);
794 rtx retval_note = find_reg_note (XEXP (note, 0),
795 REG_RETVAL, NULL_RTX);
796 REG_NOTES (new_libcall_insn)
797 = gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0),
798 REG_NOTES (new_libcall_insn));
799 XEXP (retval_note, 0) = new_libcall_insn;
802 /* Do not call delete_insn here since that may change
803 the basic block boundaries which upsets some callers. */
804 PUT_CODE (insn, NOTE);
805 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
806 NOTE_SOURCE_FILE (insn) = 0;
812 /* Delete any jump tables never referenced. We can't delete them at the
813 time of removing tablejump insn as they are referenced by the preceding
814 insns computing the destination, so we delay deleting and garbagecollect
815 them once life information is computed. */
817 delete_dead_jumptables ()
820 for (insn = get_insns (); insn; insn = next)
822 next = NEXT_INSN (insn);
823 if (GET_CODE (insn) == CODE_LABEL
824 && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
825 && GET_CODE (next) == JUMP_INSN
826 && (GET_CODE (PATTERN (next)) == ADDR_VEC
827 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
830 fprintf (rtl_dump_file, "Dead jumptable %i removed\n", INSN_UID (insn));
831 delete_insn (NEXT_INSN (insn));
833 next = NEXT_INSN (next);
838 /* Determine if the stack pointer is constant over the life of the function.
839 Only useful before prologues have been emitted. */
842 notice_stack_pointer_modification_1 (x, pat, data)
844 rtx pat ATTRIBUTE_UNUSED;
845 void *data ATTRIBUTE_UNUSED;
847 if (x == stack_pointer_rtx
848 /* The stack pointer is only modified indirectly as the result
849 of a push until later in flow. See the comments in rtl.texi
850 regarding Embedded Side-Effects on Addresses. */
851 || (GET_CODE (x) == MEM
852 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
853 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
854 current_function_sp_is_unchanging = 0;
858 notice_stack_pointer_modification (f)
863 /* Assume that the stack pointer is unchanging if alloca hasn't
865 current_function_sp_is_unchanging = !current_function_calls_alloca;
866 if (! current_function_sp_is_unchanging)
869 for (insn = f; insn; insn = NEXT_INSN (insn))
873 /* Check if insn modifies the stack pointer. */
874 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
876 if (! current_function_sp_is_unchanging)
882 /* Mark a register in SET. Hard registers in large modes get all
883 of their component registers set as well. */
890 regset set = (regset) xset;
891 int regno = REGNO (reg);
893 if (GET_MODE (reg) == BLKmode)
896 SET_REGNO_REG_SET (set, regno);
897 if (regno < FIRST_PSEUDO_REGISTER)
899 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
901 SET_REGNO_REG_SET (set, regno + n);
905 /* Mark those regs which are needed at the end of the function as live
906 at the end of the last basic block. */
909 mark_regs_live_at_end (set)
914 /* If exiting needs the right stack value, consider the stack pointer
915 live at the end of the function. */
916 if ((HAVE_epilogue && reload_completed)
917 || ! EXIT_IGNORE_STACK
918 || (! FRAME_POINTER_REQUIRED
919 && ! current_function_calls_alloca
920 && flag_omit_frame_pointer)
921 || current_function_sp_is_unchanging)
923 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
926 /* Mark the frame pointer if needed at the end of the function. If
927 we end up eliminating it, it will be removed from the live list
928 of each basic block by reload. */
930 if (! reload_completed || frame_pointer_needed)
932 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
933 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
934 /* If they are different, also mark the hard frame pointer as live. */
935 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
936 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
940 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
941 /* Many architectures have a GP register even without flag_pic.
942 Assume the pic register is not in use, or will be handled by
943 other means, if it is not fixed. */
944 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
945 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
946 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
949 /* Mark all global registers, and all registers used by the epilogue
950 as being live at the end of the function since they may be
951 referenced by our caller. */
952 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
953 if (global_regs[i] || EPILOGUE_USES (i))
954 SET_REGNO_REG_SET (set, i);
956 if (HAVE_epilogue && reload_completed)
958 /* Mark all call-saved registers that we actually used. */
959 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
960 if (regs_ever_live[i] && ! LOCAL_REGNO (i)
961 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
962 SET_REGNO_REG_SET (set, i);
965 #ifdef EH_RETURN_DATA_REGNO
966 /* Mark the registers that will contain data for the handler. */
967 if (reload_completed && current_function_calls_eh_return)
970 unsigned regno = EH_RETURN_DATA_REGNO(i);
971 if (regno == INVALID_REGNUM)
973 SET_REGNO_REG_SET (set, regno);
976 #ifdef EH_RETURN_STACKADJ_RTX
977 if ((! HAVE_epilogue || ! reload_completed)
978 && current_function_calls_eh_return)
980 rtx tmp = EH_RETURN_STACKADJ_RTX;
981 if (tmp && REG_P (tmp))
985 #ifdef EH_RETURN_HANDLER_RTX
986 if ((! HAVE_epilogue || ! reload_completed)
987 && current_function_calls_eh_return)
989 rtx tmp = EH_RETURN_HANDLER_RTX;
990 if (tmp && REG_P (tmp))
995 /* Mark function return value. */
996 diddle_return_value (mark_reg, set);
999 /* Callback function for for_each_successor_phi. DATA is a regset.
1000 Sets the SRC_REGNO, the regno of the phi alternative for phi node
1001 INSN, in the regset. */
1004 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
1005 rtx insn ATTRIBUTE_UNUSED;
1006 int dest_regno ATTRIBUTE_UNUSED;
1010 regset live = (regset) data;
1011 SET_REGNO_REG_SET (live, src_regno);
1015 /* Propagate global life info around the graph of basic blocks. Begin
1016 considering blocks with their corresponding bit set in BLOCKS_IN.
1017 If BLOCKS_IN is null, consider it the universal set.
1019 BLOCKS_OUT is set for every block that was changed. */
1022 calculate_global_regs_live (blocks_in, blocks_out, flags)
1023 sbitmap blocks_in, blocks_out;
1026 basic_block *queue, *qhead, *qtail, *qend;
1027 regset tmp, new_live_at_end, call_used;
1028 regset_head tmp_head, call_used_head;
1029 regset_head new_live_at_end_head;
1032 tmp = INITIALIZE_REG_SET (tmp_head);
1033 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
1034 call_used = INITIALIZE_REG_SET (call_used_head);
1036 /* Inconveniently, this is only redily available in hard reg set form. */
1037 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
1038 if (call_used_regs[i])
1039 SET_REGNO_REG_SET (call_used, i);
1041 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1042 because the `head == tail' style test for an empty queue doesn't
1043 work with a full queue. */
1044 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
1046 qhead = qend = queue + n_basic_blocks + 2;
1048 /* Queue the blocks set in the initial mask. Do this in reverse block
1049 number order so that we are more likely for the first round to do
1050 useful work. We use AUX non-null to flag that the block is queued. */
1053 /* Clear out the garbage that might be hanging out in bb->aux. */
1054 for (i = n_basic_blocks - 1; i >= 0; --i)
1055 BASIC_BLOCK (i)->aux = NULL;
1057 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
1059 basic_block bb = BASIC_BLOCK (i);
1066 for (i = 0; i < n_basic_blocks; ++i)
1068 basic_block bb = BASIC_BLOCK (i);
1075 sbitmap_zero (blocks_out);
1077 /* We work through the queue until there are no more blocks. What
1078 is live at the end of this block is precisely the union of what
1079 is live at the beginning of all its successors. So, we set its
1080 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1081 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1082 this block by walking through the instructions in this block in
1083 reverse order and updating as we go. If that changed
1084 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1085 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1087 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1088 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1089 must either be live at the end of the block, or used within the
1090 block. In the latter case, it will certainly never disappear
1091 from GLOBAL_LIVE_AT_START. In the former case, the register
1092 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1093 for one of the successor blocks. By induction, that cannot
1095 while (qhead != qtail)
1097 int rescan, changed;
1106 /* Begin by propagating live_at_start from the successor blocks. */
1107 CLEAR_REG_SET (new_live_at_end);
1108 for (e = bb->succ; e; e = e->succ_next)
1110 basic_block sb = e->dest;
1112 /* Call-clobbered registers die across exception and call edges. */
1113 /* ??? Abnormal call edges ignored for the moment, as this gets
1114 confused by sibling call edges, which crashes reg-stack. */
1115 if (e->flags & EDGE_EH)
1117 bitmap_operation (tmp, sb->global_live_at_start,
1118 call_used, BITMAP_AND_COMPL);
1119 IOR_REG_SET (new_live_at_end, tmp);
1122 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
1125 /* The all-important stack pointer must always be live. */
1126 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
1128 /* Before reload, there are a few registers that must be forced
1129 live everywhere -- which might not already be the case for
1130 blocks within infinite loops. */
1131 if (! reload_completed)
1133 /* Any reference to any pseudo before reload is a potential
1134 reference of the frame pointer. */
1135 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
1137 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1138 /* Pseudos with argument area equivalences may require
1139 reloading via the argument pointer. */
1140 if (fixed_regs[ARG_POINTER_REGNUM])
1141 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
1144 /* Any constant, or pseudo with constant equivalences, may
1145 require reloading from memory using the pic register. */
1146 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
1147 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
1148 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
1151 /* Regs used in phi nodes are not included in
1152 global_live_at_start, since they are live only along a
1153 particular edge. Set those regs that are live because of a
1154 phi node alternative corresponding to this particular block. */
1156 for_each_successor_phi (bb, &set_phi_alternative_reg,
1159 if (bb == ENTRY_BLOCK_PTR)
1161 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1165 /* On our first pass through this block, we'll go ahead and continue.
1166 Recognize first pass by local_set NULL. On subsequent passes, we
1167 get to skip out early if live_at_end wouldn't have changed. */
1169 if (bb->local_set == NULL)
1171 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1172 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1177 /* If any bits were removed from live_at_end, we'll have to
1178 rescan the block. This wouldn't be necessary if we had
1179 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1180 local_live is really dependent on live_at_end. */
1181 CLEAR_REG_SET (tmp);
1182 rescan = bitmap_operation (tmp, bb->global_live_at_end,
1183 new_live_at_end, BITMAP_AND_COMPL);
1187 /* If any of the registers in the new live_at_end set are
1188 conditionally set in this basic block, we must rescan.
1189 This is because conditional lifetimes at the end of the
1190 block do not just take the live_at_end set into account,
1191 but also the liveness at the start of each successor
1192 block. We can miss changes in those sets if we only
1193 compare the new live_at_end against the previous one. */
1194 CLEAR_REG_SET (tmp);
1195 rescan = bitmap_operation (tmp, new_live_at_end,
1196 bb->cond_local_set, BITMAP_AND);
1201 /* Find the set of changed bits. Take this opportunity
1202 to notice that this set is empty and early out. */
1203 CLEAR_REG_SET (tmp);
1204 changed = bitmap_operation (tmp, bb->global_live_at_end,
1205 new_live_at_end, BITMAP_XOR);
1209 /* If any of the changed bits overlap with local_set,
1210 we'll have to rescan the block. Detect overlap by
1211 the AND with ~local_set turning off bits. */
1212 rescan = bitmap_operation (tmp, tmp, bb->local_set,
1217 /* Let our caller know that BB changed enough to require its
1218 death notes updated. */
1220 SET_BIT (blocks_out, bb->index);
1224 /* Add to live_at_start the set of all registers in
1225 new_live_at_end that aren't in the old live_at_end. */
1227 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
1229 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1231 changed = bitmap_operation (bb->global_live_at_start,
1232 bb->global_live_at_start,
1239 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1241 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1242 into live_at_start. */
1243 propagate_block (bb, new_live_at_end, bb->local_set,
1244 bb->cond_local_set, flags);
1246 /* If live_at start didn't change, no need to go farther. */
1247 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
1250 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
1253 /* Queue all predecessors of BB so that we may re-examine
1254 their live_at_end. */
1255 for (e = bb->pred; e; e = e->pred_next)
1257 basic_block pb = e->src;
1258 if (pb->aux == NULL)
1269 FREE_REG_SET (new_live_at_end);
1270 FREE_REG_SET (call_used);
1274 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
1276 basic_block bb = BASIC_BLOCK (i);
1277 FREE_REG_SET (bb->local_set);
1278 FREE_REG_SET (bb->cond_local_set);
1283 for (i = n_basic_blocks - 1; i >= 0; --i)
1285 basic_block bb = BASIC_BLOCK (i);
1286 FREE_REG_SET (bb->local_set);
1287 FREE_REG_SET (bb->cond_local_set);
1294 /* Subroutines of life analysis. */
1296 /* Allocate the permanent data structures that represent the results
1297 of life analysis. Not static since used also for stupid life analysis. */
1300 allocate_bb_life_data ()
1304 for (i = 0; i < n_basic_blocks; i++)
1306 basic_block bb = BASIC_BLOCK (i);
1308 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1309 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1312 ENTRY_BLOCK_PTR->global_live_at_end
1313 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1314 EXIT_BLOCK_PTR->global_live_at_start
1315 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1317 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1321 allocate_reg_life_data ()
1325 max_regno = max_reg_num ();
1327 /* Recalculate the register space, in case it has grown. Old style
1328 vector oriented regsets would set regset_{size,bytes} here also. */
1329 allocate_reg_info (max_regno, FALSE, FALSE);
1331 /* Reset all the data we'll collect in propagate_block and its
1333 for (i = 0; i < max_regno; i++)
1337 REG_N_DEATHS (i) = 0;
1338 REG_N_CALLS_CROSSED (i) = 0;
1339 REG_LIVE_LENGTH (i) = 0;
1340 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
1344 /* Delete dead instructions for propagate_block. */
1347 propagate_block_delete_insn (bb, insn)
1351 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
1354 /* If the insn referred to a label, and that label was attached to
1355 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1356 pretty much mandatory to delete it, because the ADDR_VEC may be
1357 referencing labels that no longer exist.
1359 INSN may reference a deleted label, particularly when a jump
1360 table has been optimized into a direct jump. There's no
1361 real good way to fix up the reference to the deleted label
1362 when the label is deleted, so we just allow it here.
1364 After dead code elimination is complete, we do search for
1365 any REG_LABEL notes which reference deleted labels as a
1368 if (inote && GET_CODE (inote) == CODE_LABEL)
1370 rtx label = XEXP (inote, 0);
1373 /* The label may be forced if it has been put in the constant
1374 pool. If that is the only use we must discard the table
1375 jump following it, but not the label itself. */
1376 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
1377 && (next = next_nonnote_insn (label)) != NULL
1378 && GET_CODE (next) == JUMP_INSN
1379 && (GET_CODE (PATTERN (next)) == ADDR_VEC
1380 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
1382 rtx pat = PATTERN (next);
1383 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
1384 int len = XVECLEN (pat, diff_vec_p);
1387 for (i = 0; i < len; i++)
1388 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
1394 if (bb->end == insn)
1398 purge_dead_edges (bb);
1401 /* Delete dead libcalls for propagate_block. Return the insn
1402 before the libcall. */
1405 propagate_block_delete_libcall ( insn, note)
1408 rtx first = XEXP (note, 0);
1409 rtx before = PREV_INSN (first);
1411 delete_insn_chain (first, insn);
1415 /* Update the life-status of regs for one insn. Return the previous insn. */
1418 propagate_one_insn (pbi, insn)
1419 struct propagate_block_info *pbi;
1422 rtx prev = PREV_INSN (insn);
1423 int flags = pbi->flags;
1424 int insn_is_dead = 0;
1425 int libcall_is_dead = 0;
1429 if (! INSN_P (insn))
1432 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1433 if (flags & PROP_SCAN_DEAD_CODE)
1435 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
1436 libcall_is_dead = (insn_is_dead && note != 0
1437 && libcall_dead_p (pbi, note, insn));
1440 /* If an instruction consists of just dead store(s) on final pass,
1442 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
1444 /* If we're trying to delete a prologue or epilogue instruction
1445 that isn't flagged as possibly being dead, something is wrong.
1446 But if we are keeping the stack pointer depressed, we might well
1447 be deleting insns that are used to compute the amount to update
1448 it by, so they are fine. */
1449 if (reload_completed
1450 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1451 && (TYPE_RETURNS_STACK_DEPRESSED
1452 (TREE_TYPE (current_function_decl))))
1453 && (((HAVE_epilogue || HAVE_prologue)
1454 && prologue_epilogue_contains (insn))
1455 || (HAVE_sibcall_epilogue
1456 && sibcall_epilogue_contains (insn)))
1457 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
1460 /* Record sets. Do this even for dead instructions, since they
1461 would have killed the values if they hadn't been deleted. */
1462 mark_set_regs (pbi, PATTERN (insn), insn);
1464 /* CC0 is now known to be dead. Either this insn used it,
1465 in which case it doesn't anymore, or clobbered it,
1466 so the next insn can't use it. */
1469 if (libcall_is_dead)
1470 prev = propagate_block_delete_libcall ( insn, note);
1472 propagate_block_delete_insn (pbi->bb, insn);
1477 /* See if this is an increment or decrement that can be merged into
1478 a following memory address. */
1481 rtx x = single_set (insn);
1483 /* Does this instruction increment or decrement a register? */
1484 if ((flags & PROP_AUTOINC)
1486 && GET_CODE (SET_DEST (x)) == REG
1487 && (GET_CODE (SET_SRC (x)) == PLUS
1488 || GET_CODE (SET_SRC (x)) == MINUS)
1489 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1490 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1491 /* Ok, look for a following memory ref we can combine with.
1492 If one is found, change the memory ref to a PRE_INC
1493 or PRE_DEC, cancel this insn, and return 1.
1494 Return 0 if nothing has been done. */
1495 && try_pre_increment_1 (pbi, insn))
1498 #endif /* AUTO_INC_DEC */
1500 CLEAR_REG_SET (pbi->new_set);
1502 /* If this is not the final pass, and this insn is copying the value of
1503 a library call and it's dead, don't scan the insns that perform the
1504 library call, so that the call's arguments are not marked live. */
1505 if (libcall_is_dead)
1507 /* Record the death of the dest reg. */
1508 mark_set_regs (pbi, PATTERN (insn), insn);
1510 insn = XEXP (note, 0);
1511 return PREV_INSN (insn);
1513 else if (GET_CODE (PATTERN (insn)) == SET
1514 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1515 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1516 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1517 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1518 /* We have an insn to pop a constant amount off the stack.
1519 (Such insns use PLUS regardless of the direction of the stack,
1520 and any insn to adjust the stack by a constant is always a pop.)
1521 These insns, if not dead stores, have no effect on life. */
1525 /* Any regs live at the time of a call instruction must not go
1526 in a register clobbered by calls. Find all regs now live and
1527 record this for them. */
1529 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
1530 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
1531 { REG_N_CALLS_CROSSED (i)++; });
1533 /* Record sets. Do this even for dead instructions, since they
1534 would have killed the values if they hadn't been deleted. */
1535 mark_set_regs (pbi, PATTERN (insn), insn);
1537 if (GET_CODE (insn) == CALL_INSN)
1543 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1544 cond = COND_EXEC_TEST (PATTERN (insn));
1546 /* Non-constant calls clobber memory. */
1547 if (! CONST_OR_PURE_CALL_P (insn))
1549 free_EXPR_LIST_list (&pbi->mem_set_list);
1550 pbi->mem_set_list_len = 0;
1553 /* There may be extra registers to be clobbered. */
1554 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1556 note = XEXP (note, 1))
1557 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
1558 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
1559 cond, insn, pbi->flags);
1561 /* Calls change all call-used and global registers. */
1562 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1563 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1565 /* We do not want REG_UNUSED notes for these registers. */
1566 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
1568 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
1572 /* If an insn doesn't use CC0, it becomes dead since we assume
1573 that every insn clobbers it. So show it dead here;
1574 mark_used_regs will set it live if it is referenced. */
1579 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
1581 /* Sometimes we may have inserted something before INSN (such as a move)
1582 when we make an auto-inc. So ensure we will scan those insns. */
1584 prev = PREV_INSN (insn);
1587 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1593 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1594 cond = COND_EXEC_TEST (PATTERN (insn));
1596 /* Calls use their arguments. */
1597 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1599 note = XEXP (note, 1))
1600 if (GET_CODE (XEXP (note, 0)) == USE)
1601 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
1604 /* The stack ptr is used (honorarily) by a CALL insn. */
1605 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
1607 /* Calls may also reference any of the global registers,
1608 so they are made live. */
1609 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1611 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
1616 /* On final pass, update counts of how many insns in which each reg
1618 if (flags & PROP_REG_INFO)
1619 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
1620 { REG_LIVE_LENGTH (i)++; });
1625 /* Initialize a propagate_block_info struct for public consumption.
1626 Note that the structure itself is opaque to this file, but that
1627 the user can use the regsets provided here. */
1629 struct propagate_block_info *
1630 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
1632 regset live, local_set, cond_local_set;
1635 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
1638 pbi->reg_live = live;
1639 pbi->mem_set_list = NULL_RTX;
1640 pbi->mem_set_list_len = 0;
1641 pbi->local_set = local_set;
1642 pbi->cond_local_set = cond_local_set;
1646 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
1647 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
1649 pbi->reg_next_use = NULL;
1651 pbi->new_set = BITMAP_XMALLOC ();
1653 #ifdef HAVE_conditional_execution
1654 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
1655 free_reg_cond_life_info);
1656 pbi->reg_cond_reg = BITMAP_XMALLOC ();
1658 /* If this block ends in a conditional branch, for each register live
1659 from one side of the branch and not the other, record the register
1660 as conditionally dead. */
1661 if (GET_CODE (bb->end) == JUMP_INSN
1662 && any_condjump_p (bb->end))
1664 regset_head diff_head;
1665 regset diff = INITIALIZE_REG_SET (diff_head);
1666 basic_block bb_true, bb_false;
1667 rtx cond_true, cond_false, set_src;
1670 /* Identify the successor blocks. */
1671 bb_true = bb->succ->dest;
1672 if (bb->succ->succ_next != NULL)
1674 bb_false = bb->succ->succ_next->dest;
1676 if (bb->succ->flags & EDGE_FALLTHRU)
1678 basic_block t = bb_false;
1682 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
1687 /* This can happen with a conditional jump to the next insn. */
1688 if (JUMP_LABEL (bb->end) != bb_true->head)
1691 /* Simplest way to do nothing. */
1695 /* Extract the condition from the branch. */
1696 set_src = SET_SRC (pc_set (bb->end));
1697 cond_true = XEXP (set_src, 0);
1698 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
1699 GET_MODE (cond_true), XEXP (cond_true, 0),
1700 XEXP (cond_true, 1));
1701 if (GET_CODE (XEXP (set_src, 1)) == PC)
1704 cond_false = cond_true;
1708 /* Compute which register lead different lives in the successors. */
1709 if (bitmap_operation (diff, bb_true->global_live_at_start,
1710 bb_false->global_live_at_start, BITMAP_XOR))
1712 rtx reg = XEXP (cond_true, 0);
1714 if (GET_CODE (reg) == SUBREG)
1715 reg = SUBREG_REG (reg);
1717 if (GET_CODE (reg) != REG)
1720 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
1722 /* For each such register, mark it conditionally dead. */
1723 EXECUTE_IF_SET_IN_REG_SET
1726 struct reg_cond_life_info *rcli;
1729 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
1731 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
1735 rcli->condition = cond;
1736 rcli->stores = const0_rtx;
1737 rcli->orig_condition = cond;
1739 splay_tree_insert (pbi->reg_cond_dead, i,
1740 (splay_tree_value) rcli);
1744 FREE_REG_SET (diff);
1748 /* If this block has no successors, any stores to the frame that aren't
1749 used later in the block are dead. So make a pass over the block
1750 recording any such that are made and show them dead at the end. We do
1751 a very conservative and simple job here. */
1753 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1754 && (TYPE_RETURNS_STACK_DEPRESSED
1755 (TREE_TYPE (current_function_decl))))
1756 && (flags & PROP_SCAN_DEAD_CODE)
1757 && (bb->succ == NULL
1758 || (bb->succ->succ_next == NULL
1759 && bb->succ->dest == EXIT_BLOCK_PTR
1760 && ! current_function_calls_eh_return)))
1763 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
1764 if (GET_CODE (insn) == INSN
1765 && (set = single_set (insn))
1766 && GET_CODE (SET_DEST (set)) == MEM)
1768 rtx mem = SET_DEST (set);
1769 rtx canon_mem = canon_rtx (mem);
1771 /* This optimization is performed by faking a store to the
1772 memory at the end of the block. This doesn't work for
1773 unchanging memories because multiple stores to unchanging
1774 memory is illegal and alias analysis doesn't consider it. */
1775 if (RTX_UNCHANGING_P (canon_mem))
1778 if (XEXP (canon_mem, 0) == frame_pointer_rtx
1779 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
1780 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
1781 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
1782 add_to_mem_set_list (pbi, canon_mem);
1789 /* Release a propagate_block_info struct. */
1792 free_propagate_block_info (pbi)
1793 struct propagate_block_info *pbi;
1795 free_EXPR_LIST_list (&pbi->mem_set_list);
1797 BITMAP_XFREE (pbi->new_set);
1799 #ifdef HAVE_conditional_execution
1800 splay_tree_delete (pbi->reg_cond_dead);
1801 BITMAP_XFREE (pbi->reg_cond_reg);
1804 if (pbi->reg_next_use)
1805 free (pbi->reg_next_use);
1810 /* Compute the registers live at the beginning of a basic block BB from
1811 those live at the end.
1813 When called, REG_LIVE contains those live at the end. On return, it
1814 contains those live at the beginning.
1816 LOCAL_SET, if non-null, will be set with all registers killed
1817 unconditionally by this basic block.
1818 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
1819 killed conditionally by this basic block. If there is any unconditional
1820 set of a register, then the corresponding bit will be set in LOCAL_SET
1821 and cleared in COND_LOCAL_SET.
1822 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
1823 case, the resulting set will be equal to the union of the two sets that
1824 would otherwise be computed.
1826 Return non-zero if an INSN is deleted (i.e. by dead code removal). */
1829 propagate_block (bb, live, local_set, cond_local_set, flags)
1833 regset cond_local_set;
1836 struct propagate_block_info *pbi;
1840 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
1842 if (flags & PROP_REG_INFO)
1846 /* Process the regs live at the end of the block.
1847 Mark them as not local to any one basic block. */
1848 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
1849 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
1852 /* Scan the block an insn at a time from end to beginning. */
1855 for (insn = bb->end;; insn = prev)
1857 /* If this is a call to `setjmp' et al, warn if any
1858 non-volatile datum is live. */
1859 if ((flags & PROP_REG_INFO)
1860 && GET_CODE (insn) == CALL_INSN
1861 && find_reg_note (insn, REG_SETJMP, NULL))
1862 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
1864 prev = propagate_one_insn (pbi, insn);
1865 changed |= NEXT_INSN (prev) != insn;
1867 if (insn == bb->head)
1871 free_propagate_block_info (pbi);
1876 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1877 (SET expressions whose destinations are registers dead after the insn).
1878 NEEDED is the regset that says which regs are alive after the insn.
1880 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
1882 If X is the entire body of an insn, NOTES contains the reg notes
1883 pertaining to the insn. */
1886 insn_dead_p (pbi, x, call_ok, notes)
1887 struct propagate_block_info *pbi;
1890 rtx notes ATTRIBUTE_UNUSED;
1892 enum rtx_code code = GET_CODE (x);
1895 /* As flow is invoked after combine, we must take existing AUTO_INC
1896 expressions into account. */
1897 for (; notes; notes = XEXP (notes, 1))
1899 if (REG_NOTE_KIND (notes) == REG_INC)
1901 int regno = REGNO (XEXP (notes, 0));
1903 /* Don't delete insns to set global regs. */
1904 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
1905 || REGNO_REG_SET_P (pbi->reg_live, regno))
1911 /* If setting something that's a reg or part of one,
1912 see if that register's altered value will be live. */
1916 rtx r = SET_DEST (x);
1919 if (GET_CODE (r) == CC0)
1920 return ! pbi->cc0_live;
1923 /* A SET that is a subroutine call cannot be dead. */
1924 if (GET_CODE (SET_SRC (x)) == CALL)
1930 /* Don't eliminate loads from volatile memory or volatile asms. */
1931 else if (volatile_refs_p (SET_SRC (x)))
1934 if (GET_CODE (r) == MEM)
1938 if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode)
1941 canon_r = canon_rtx (r);
1943 /* Walk the set of memory locations we are currently tracking
1944 and see if one is an identical match to this memory location.
1945 If so, this memory write is dead (remember, we're walking
1946 backwards from the end of the block to the start). Since
1947 rtx_equal_p does not check the alias set or flags, we also
1948 must have the potential for them to conflict (anti_dependence). */
1949 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
1950 if (anti_dependence (r, XEXP (temp, 0)))
1952 rtx mem = XEXP (temp, 0);
1954 if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0))
1955 && (GET_MODE_SIZE (GET_MODE (canon_r))
1956 <= GET_MODE_SIZE (GET_MODE (mem))))
1960 /* Check if memory reference matches an auto increment. Only
1961 post increment/decrement or modify are valid. */
1962 if (GET_MODE (mem) == GET_MODE (r)
1963 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
1964 || GET_CODE (XEXP (mem, 0)) == POST_INC
1965 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
1966 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
1967 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
1974 while (GET_CODE (r) == SUBREG
1975 || GET_CODE (r) == STRICT_LOW_PART
1976 || GET_CODE (r) == ZERO_EXTRACT)
1979 if (GET_CODE (r) == REG)
1981 int regno = REGNO (r);
1984 if (REGNO_REG_SET_P (pbi->reg_live, regno))
1987 /* If this is a hard register, verify that subsequent
1988 words are not needed. */
1989 if (regno < FIRST_PSEUDO_REGISTER)
1991 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
1994 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
1998 /* Don't delete insns to set global regs. */
1999 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2002 /* Make sure insns to set the stack pointer aren't deleted. */
2003 if (regno == STACK_POINTER_REGNUM)
2006 /* ??? These bits might be redundant with the force live bits
2007 in calculate_global_regs_live. We would delete from
2008 sequential sets; whether this actually affects real code
2009 for anything but the stack pointer I don't know. */
2010 /* Make sure insns to set the frame pointer aren't deleted. */
2011 if (regno == FRAME_POINTER_REGNUM
2012 && (! reload_completed || frame_pointer_needed))
2014 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2015 if (regno == HARD_FRAME_POINTER_REGNUM
2016 && (! reload_completed || frame_pointer_needed))
2020 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2021 /* Make sure insns to set arg pointer are never deleted
2022 (if the arg pointer isn't fixed, there will be a USE
2023 for it, so we can treat it normally). */
2024 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2028 /* Otherwise, the set is dead. */
2034 /* If performing several activities, insn is dead if each activity
2035 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2036 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2038 else if (code == PARALLEL)
2040 int i = XVECLEN (x, 0);
2042 for (i--; i >= 0; i--)
2043 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
2044 && GET_CODE (XVECEXP (x, 0, i)) != USE
2045 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
2051 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2052 is not necessarily true for hard registers. */
2053 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
2054 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
2055 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
2058 /* We do not check other CLOBBER or USE here. An insn consisting of just
2059 a CLOBBER or just a USE should not be deleted. */
2063 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2064 return 1 if the entire library call is dead.
2065 This is true if INSN copies a register (hard or pseudo)
2066 and if the hard return reg of the call insn is dead.
2067 (The caller should have tested the destination of the SET inside
2068 INSN already for death.)
2070 If this insn doesn't just copy a register, then we don't
2071 have an ordinary libcall. In that case, cse could not have
2072 managed to substitute the source for the dest later on,
2073 so we can assume the libcall is dead.
2075 PBI is the block info giving pseudoregs live before this insn.
2076 NOTE is the REG_RETVAL note of the insn. */
2079 libcall_dead_p (pbi, note, insn)
2080 struct propagate_block_info *pbi;
2084 rtx x = single_set (insn);
2088 rtx r = SET_SRC (x);
2090 if (GET_CODE (r) == REG)
2092 rtx call = XEXP (note, 0);
2096 /* Find the call insn. */
2097 while (call != insn && GET_CODE (call) != CALL_INSN)
2098 call = NEXT_INSN (call);
2100 /* If there is none, do nothing special,
2101 since ordinary death handling can understand these insns. */
2105 /* See if the hard reg holding the value is dead.
2106 If this is a PARALLEL, find the call within it. */
2107 call_pat = PATTERN (call);
2108 if (GET_CODE (call_pat) == PARALLEL)
2110 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
2111 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
2112 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
2115 /* This may be a library call that is returning a value
2116 via invisible pointer. Do nothing special, since
2117 ordinary death handling can understand these insns. */
2121 call_pat = XVECEXP (call_pat, 0, i);
2124 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
2130 /* Return 1 if register REGNO was used before it was set, i.e. if it is
2131 live at function entry. Don't count global register variables, variables
2132 in registers that can be used for function arg passing, or variables in
2133 fixed hard registers. */
2136 regno_uninitialized (regno)
2139 if (n_basic_blocks == 0
2140 || (regno < FIRST_PSEUDO_REGISTER
2141 && (global_regs[regno]
2142 || fixed_regs[regno]
2143 || FUNCTION_ARG_REGNO_P (regno))))
2146 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
2149 /* 1 if register REGNO was alive at a place where `setjmp' was called
2150 and was set more than once or is an argument.
2151 Such regs may be clobbered by `longjmp'. */
2154 regno_clobbered_at_setjmp (regno)
2157 if (n_basic_blocks == 0)
2160 return ((REG_N_SETS (regno) > 1
2161 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
2162 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
2165 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2166 maximal list size; look for overlaps in mode and select the largest. */
2168 add_to_mem_set_list (pbi, mem)
2169 struct propagate_block_info *pbi;
2174 /* We don't know how large a BLKmode store is, so we must not
2175 take them into consideration. */
2176 if (GET_MODE (mem) == BLKmode)
2179 for (i = pbi->mem_set_list; i ; i = XEXP (i, 1))
2181 rtx e = XEXP (i, 0);
2182 if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0)))
2184 if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e)))
2187 /* If we must store a copy of the mem, we can just modify
2188 the mode of the stored copy. */
2189 if (pbi->flags & PROP_AUTOINC)
2190 PUT_MODE (e, GET_MODE (mem));
2199 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN)
2202 /* Store a copy of mem, otherwise the address may be
2203 scrogged by find_auto_inc. */
2204 if (pbi->flags & PROP_AUTOINC)
2205 mem = shallow_copy_rtx (mem);
2207 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
2208 pbi->mem_set_list_len++;
2212 /* INSN references memory, possibly using autoincrement addressing modes.
2213 Find any entries on the mem_set_list that need to be invalidated due
2214 to an address change. */
2217 invalidate_mems_from_autoinc (pbi, insn)
2218 struct propagate_block_info *pbi;
2221 rtx note = REG_NOTES (insn);
2222 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
2223 if (REG_NOTE_KIND (note) == REG_INC)
2224 invalidate_mems_from_set (pbi, XEXP (note, 0));
2227 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2230 invalidate_mems_from_set (pbi, exp)
2231 struct propagate_block_info *pbi;
2234 rtx temp = pbi->mem_set_list;
2235 rtx prev = NULL_RTX;
2240 next = XEXP (temp, 1);
2241 if (reg_overlap_mentioned_p (exp, XEXP (temp, 0)))
2243 /* Splice this entry out of the list. */
2245 XEXP (prev, 1) = next;
2247 pbi->mem_set_list = next;
2248 free_EXPR_LIST_node (temp);
2249 pbi->mem_set_list_len--;
2257 /* Process the registers that are set within X. Their bits are set to
2258 1 in the regset DEAD, because they are dead prior to this insn.
2260 If INSN is nonzero, it is the insn being processed.
2262 FLAGS is the set of operations to perform. */
2265 mark_set_regs (pbi, x, insn)
2266 struct propagate_block_info *pbi;
2269 rtx cond = NULL_RTX;
2274 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2276 if (REG_NOTE_KIND (link) == REG_INC)
2277 mark_set_1 (pbi, SET, XEXP (link, 0),
2278 (GET_CODE (x) == COND_EXEC
2279 ? COND_EXEC_TEST (x) : NULL_RTX),
2283 switch (code = GET_CODE (x))
2287 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
2291 cond = COND_EXEC_TEST (x);
2292 x = COND_EXEC_CODE (x);
2299 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2301 rtx sub = XVECEXP (x, 0, i);
2302 switch (code = GET_CODE (sub))
2305 if (cond != NULL_RTX)
2308 cond = COND_EXEC_TEST (sub);
2309 sub = COND_EXEC_CODE (sub);
2310 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
2316 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
2331 /* Process a single set, which appears in INSN. REG (which may not
2332 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2333 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2334 If the set is conditional (because it appear in a COND_EXEC), COND
2335 will be the condition. */
2338 mark_set_1 (pbi, code, reg, cond, insn, flags)
2339 struct propagate_block_info *pbi;
2341 rtx reg, cond, insn;
2344 int regno_first = -1, regno_last = -1;
2345 unsigned long not_dead = 0;
2348 /* Modifying just one hardware register of a multi-reg value or just a
2349 byte field of a register does not mean the value from before this insn
2350 is now dead. Of course, if it was dead after it's unused now. */
2352 switch (GET_CODE (reg))
2355 /* Some targets place small structures in registers for return values of
2356 functions. We have to detect this case specially here to get correct
2357 flow information. */
2358 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
2359 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
2360 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
2366 case STRICT_LOW_PART:
2367 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2369 reg = XEXP (reg, 0);
2370 while (GET_CODE (reg) == SUBREG
2371 || GET_CODE (reg) == ZERO_EXTRACT
2372 || GET_CODE (reg) == SIGN_EXTRACT
2373 || GET_CODE (reg) == STRICT_LOW_PART);
2374 if (GET_CODE (reg) == MEM)
2376 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
2380 regno_last = regno_first = REGNO (reg);
2381 if (regno_first < FIRST_PSEUDO_REGISTER)
2382 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
2386 if (GET_CODE (SUBREG_REG (reg)) == REG)
2388 enum machine_mode outer_mode = GET_MODE (reg);
2389 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
2391 /* Identify the range of registers affected. This is moderately
2392 tricky for hard registers. See alter_subreg. */
2394 regno_last = regno_first = REGNO (SUBREG_REG (reg));
2395 if (regno_first < FIRST_PSEUDO_REGISTER)
2397 regno_first += subreg_regno_offset (regno_first, inner_mode,
2400 regno_last = (regno_first
2401 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
2403 /* Since we've just adjusted the register number ranges, make
2404 sure REG matches. Otherwise some_was_live will be clear
2405 when it shouldn't have been, and we'll create incorrect
2406 REG_UNUSED notes. */
2407 reg = gen_rtx_REG (outer_mode, regno_first);
2411 /* If the number of words in the subreg is less than the number
2412 of words in the full register, we have a well-defined partial
2413 set. Otherwise the high bits are undefined.
2415 This is only really applicable to pseudos, since we just took
2416 care of multi-word hard registers. */
2417 if (((GET_MODE_SIZE (outer_mode)
2418 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
2419 < ((GET_MODE_SIZE (inner_mode)
2420 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
2421 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
2424 reg = SUBREG_REG (reg);
2428 reg = SUBREG_REG (reg);
2435 /* If this set is a MEM, then it kills any aliased writes.
2436 If this set is a REG, then it kills any MEMs which use the reg. */
2437 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2439 if (GET_CODE (reg) == REG)
2440 invalidate_mems_from_set (pbi, reg);
2442 /* If the memory reference had embedded side effects (autoincrement
2443 address modes. Then we may need to kill some entries on the
2445 if (insn && GET_CODE (reg) == MEM)
2446 invalidate_mems_from_autoinc (pbi, insn);
2448 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
2449 /* ??? With more effort we could track conditional memory life. */
2451 /* There are no REG_INC notes for SP, so we can't assume we'll see
2452 everything that invalidates it. To be safe, don't eliminate any
2453 stores though SP; none of them should be redundant anyway. */
2454 && ! reg_mentioned_p (stack_pointer_rtx, reg))
2455 add_to_mem_set_list (pbi, canon_rtx (reg));
2458 if (GET_CODE (reg) == REG
2459 && ! (regno_first == FRAME_POINTER_REGNUM
2460 && (! reload_completed || frame_pointer_needed))
2461 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2462 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
2463 && (! reload_completed || frame_pointer_needed))
2465 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2466 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
2470 int some_was_live = 0, some_was_dead = 0;
2472 for (i = regno_first; i <= regno_last; ++i)
2474 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
2477 /* Order of the set operation matters here since both
2478 sets may be the same. */
2479 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
2480 if (cond != NULL_RTX
2481 && ! REGNO_REG_SET_P (pbi->local_set, i))
2482 SET_REGNO_REG_SET (pbi->cond_local_set, i);
2484 SET_REGNO_REG_SET (pbi->local_set, i);
2486 if (code != CLOBBER)
2487 SET_REGNO_REG_SET (pbi->new_set, i);
2489 some_was_live |= needed_regno;
2490 some_was_dead |= ! needed_regno;
2493 #ifdef HAVE_conditional_execution
2494 /* Consider conditional death in deciding that the register needs
2496 if (some_was_live && ! not_dead
2497 /* The stack pointer is never dead. Well, not strictly true,
2498 but it's very difficult to tell from here. Hopefully
2499 combine_stack_adjustments will fix up the most egregious
2501 && regno_first != STACK_POINTER_REGNUM)
2503 for (i = regno_first; i <= regno_last; ++i)
2504 if (! mark_regno_cond_dead (pbi, i, cond))
2505 not_dead |= ((unsigned long) 1) << (i - regno_first);
2509 /* Additional data to record if this is the final pass. */
2510 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
2511 | PROP_DEATH_NOTES | PROP_AUTOINC))
2514 int blocknum = pbi->bb->index;
2517 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2519 y = pbi->reg_next_use[regno_first];
2521 /* The next use is no longer next, since a store intervenes. */
2522 for (i = regno_first; i <= regno_last; ++i)
2523 pbi->reg_next_use[i] = 0;
2526 if (flags & PROP_REG_INFO)
2528 for (i = regno_first; i <= regno_last; ++i)
2530 /* Count (weighted) references, stores, etc. This counts a
2531 register twice if it is modified, but that is correct. */
2532 REG_N_SETS (i) += 1;
2533 REG_N_REFS (i) += 1;
2534 REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb);
2536 /* The insns where a reg is live are normally counted
2537 elsewhere, but we want the count to include the insn
2538 where the reg is set, and the normal counting mechanism
2539 would not count it. */
2540 REG_LIVE_LENGTH (i) += 1;
2543 /* If this is a hard reg, record this function uses the reg. */
2544 if (regno_first < FIRST_PSEUDO_REGISTER)
2546 for (i = regno_first; i <= regno_last; i++)
2547 regs_ever_live[i] = 1;
2551 /* Keep track of which basic blocks each reg appears in. */
2552 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
2553 REG_BASIC_BLOCK (regno_first) = blocknum;
2554 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
2555 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
2559 if (! some_was_dead)
2561 if (flags & PROP_LOG_LINKS)
2563 /* Make a logical link from the next following insn
2564 that uses this register, back to this insn.
2565 The following insns have already been processed.
2567 We don't build a LOG_LINK for hard registers containing
2568 in ASM_OPERANDs. If these registers get replaced,
2569 we might wind up changing the semantics of the insn,
2570 even if reload can make what appear to be valid
2571 assignments later. */
2572 if (y && (BLOCK_NUM (y) == blocknum)
2573 && (regno_first >= FIRST_PSEUDO_REGISTER
2574 || asm_noperands (PATTERN (y)) < 0))
2575 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
2580 else if (! some_was_live)
2582 if (flags & PROP_REG_INFO)
2583 REG_N_DEATHS (regno_first) += 1;
2585 if (flags & PROP_DEATH_NOTES)
2587 /* Note that dead stores have already been deleted
2588 when possible. If we get here, we have found a
2589 dead store that cannot be eliminated (because the
2590 same insn does something useful). Indicate this
2591 by marking the reg being set as dying here. */
2593 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2598 if (flags & PROP_DEATH_NOTES)
2600 /* This is a case where we have a multi-word hard register
2601 and some, but not all, of the words of the register are
2602 needed in subsequent insns. Write REG_UNUSED notes
2603 for those parts that were not needed. This case should
2606 for (i = regno_first; i <= regno_last; ++i)
2607 if (! REGNO_REG_SET_P (pbi->reg_live, i))
2609 = alloc_EXPR_LIST (REG_UNUSED,
2610 gen_rtx_REG (reg_raw_mode[i], i),
2616 /* Mark the register as being dead. */
2618 /* The stack pointer is never dead. Well, not strictly true,
2619 but it's very difficult to tell from here. Hopefully
2620 combine_stack_adjustments will fix up the most egregious
2622 && regno_first != STACK_POINTER_REGNUM)
2624 for (i = regno_first; i <= regno_last; ++i)
2625 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
2626 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
2629 else if (GET_CODE (reg) == REG)
2631 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2632 pbi->reg_next_use[regno_first] = 0;
2635 /* If this is the last pass and this is a SCRATCH, show it will be dying
2636 here and count it. */
2637 else if (GET_CODE (reg) == SCRATCH)
2639 if (flags & PROP_DEATH_NOTES)
2641 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2645 #ifdef HAVE_conditional_execution
2646 /* Mark REGNO conditionally dead.
2647 Return true if the register is now unconditionally dead. */
2650 mark_regno_cond_dead (pbi, regno, cond)
2651 struct propagate_block_info *pbi;
2655 /* If this is a store to a predicate register, the value of the
2656 predicate is changing, we don't know that the predicate as seen
2657 before is the same as that seen after. Flush all dependent
2658 conditions from reg_cond_dead. This will make all such
2659 conditionally live registers unconditionally live. */
2660 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
2661 flush_reg_cond_reg (pbi, regno);
2663 /* If this is an unconditional store, remove any conditional
2664 life that may have existed. */
2665 if (cond == NULL_RTX)
2666 splay_tree_remove (pbi->reg_cond_dead, regno);
2669 splay_tree_node node;
2670 struct reg_cond_life_info *rcli;
2673 /* Otherwise this is a conditional set. Record that fact.
2674 It may have been conditionally used, or there may be a
2675 subsequent set with a complimentary condition. */
2677 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
2680 /* The register was unconditionally live previously.
2681 Record the current condition as the condition under
2682 which it is dead. */
2683 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
2684 rcli->condition = cond;
2685 rcli->stores = cond;
2686 rcli->orig_condition = const0_rtx;
2687 splay_tree_insert (pbi->reg_cond_dead, regno,
2688 (splay_tree_value) rcli);
2690 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2692 /* Not unconditionaly dead. */
2697 /* The register was conditionally live previously.
2698 Add the new condition to the old. */
2699 rcli = (struct reg_cond_life_info *) node->value;
2700 ncond = rcli->condition;
2701 ncond = ior_reg_cond (ncond, cond, 1);
2702 if (rcli->stores == const0_rtx)
2703 rcli->stores = cond;
2704 else if (rcli->stores != const1_rtx)
2705 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
2707 /* If the register is now unconditionally dead, remove the entry
2708 in the splay_tree. A register is unconditionally dead if the
2709 dead condition ncond is true. A register is also unconditionally
2710 dead if the sum of all conditional stores is an unconditional
2711 store (stores is true), and the dead condition is identically the
2712 same as the original dead condition initialized at the end of
2713 the block. This is a pointer compare, not an rtx_equal_p
2715 if (ncond == const1_rtx
2716 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
2717 splay_tree_remove (pbi->reg_cond_dead, regno);
2720 rcli->condition = ncond;
2722 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2724 /* Not unconditionaly dead. */
2733 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2736 free_reg_cond_life_info (value)
2737 splay_tree_value value;
2739 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
2743 /* Helper function for flush_reg_cond_reg. */
2746 flush_reg_cond_reg_1 (node, data)
2747 splay_tree_node node;
2750 struct reg_cond_life_info *rcli;
2751 int *xdata = (int *) data;
2752 unsigned int regno = xdata[0];
2754 /* Don't need to search if last flushed value was farther on in
2755 the in-order traversal. */
2756 if (xdata[1] >= (int) node->key)
2759 /* Splice out portions of the expression that refer to regno. */
2760 rcli = (struct reg_cond_life_info *) node->value;
2761 rcli->condition = elim_reg_cond (rcli->condition, regno);
2762 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
2763 rcli->stores = elim_reg_cond (rcli->stores, regno);
2765 /* If the entire condition is now false, signal the node to be removed. */
2766 if (rcli->condition == const0_rtx)
2768 xdata[1] = node->key;
2771 else if (rcli->condition == const1_rtx)
2777 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2780 flush_reg_cond_reg (pbi, regno)
2781 struct propagate_block_info *pbi;
2788 while (splay_tree_foreach (pbi->reg_cond_dead,
2789 flush_reg_cond_reg_1, pair) == -1)
2790 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
2792 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
2795 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2796 For ior/and, the ADD flag determines whether we want to add the new
2797 condition X to the old one unconditionally. If it is zero, we will
2798 only return a new expression if X allows us to simplify part of
2799 OLD, otherwise we return NULL to the caller.
2800 If ADD is nonzero, we will return a new condition in all cases. The
2801 toplevel caller of one of these functions should always pass 1 for
2805 ior_reg_cond (old, x, add)
2811 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
2813 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
2814 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
2815 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2817 if (GET_CODE (x) == GET_CODE (old)
2818 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2822 return gen_rtx_IOR (0, old, x);
2825 switch (GET_CODE (old))
2828 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
2829 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
2830 if (op0 != NULL || op1 != NULL)
2832 if (op0 == const0_rtx)
2833 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
2834 if (op1 == const0_rtx)
2835 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
2836 if (op0 == const1_rtx || op1 == const1_rtx)
2839 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
2840 else if (rtx_equal_p (x, op0))
2841 /* (x | A) | x ~ (x | A). */
2844 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
2845 else if (rtx_equal_p (x, op1))
2846 /* (A | x) | x ~ (A | x). */
2848 return gen_rtx_IOR (0, op0, op1);
2852 return gen_rtx_IOR (0, old, x);
2855 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
2856 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
2857 if (op0 != NULL || op1 != NULL)
2859 if (op0 == const1_rtx)
2860 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
2861 if (op1 == const1_rtx)
2862 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
2863 if (op0 == const0_rtx || op1 == const0_rtx)
2866 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
2867 else if (rtx_equal_p (x, op0))
2868 /* (x & A) | x ~ x. */
2871 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
2872 else if (rtx_equal_p (x, op1))
2873 /* (A & x) | x ~ x. */
2875 return gen_rtx_AND (0, op0, op1);
2879 return gen_rtx_IOR (0, old, x);
2882 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
2884 return not_reg_cond (op0);
2887 return gen_rtx_IOR (0, old, x);
2898 enum rtx_code x_code;
2900 if (x == const0_rtx)
2902 else if (x == const1_rtx)
2904 x_code = GET_CODE (x);
2907 if (GET_RTX_CLASS (x_code) == '<'
2908 && GET_CODE (XEXP (x, 0)) == REG)
2910 if (XEXP (x, 1) != const0_rtx)
2913 return gen_rtx_fmt_ee (reverse_condition (x_code),
2914 VOIDmode, XEXP (x, 0), const0_rtx);
2916 return gen_rtx_NOT (0, x);
2920 and_reg_cond (old, x, add)
2926 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
2928 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
2929 && GET_CODE (x) == reverse_condition (GET_CODE (old))
2930 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2932 if (GET_CODE (x) == GET_CODE (old)
2933 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2937 return gen_rtx_AND (0, old, x);
2940 switch (GET_CODE (old))
2943 op0 = and_reg_cond (XEXP (old, 0), x, 0);
2944 op1 = and_reg_cond (XEXP (old, 1), x, 0);
2945 if (op0 != NULL || op1 != NULL)
2947 if (op0 == const0_rtx)
2948 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
2949 if (op1 == const0_rtx)
2950 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
2951 if (op0 == const1_rtx || op1 == const1_rtx)
2954 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
2955 else if (rtx_equal_p (x, op0))
2956 /* (x | A) & x ~ x. */
2959 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
2960 else if (rtx_equal_p (x, op1))
2961 /* (A | x) & x ~ x. */
2963 return gen_rtx_IOR (0, op0, op1);
2967 return gen_rtx_AND (0, old, x);
2970 op0 = and_reg_cond (XEXP (old, 0), x, 0);
2971 op1 = and_reg_cond (XEXP (old, 1), x, 0);
2972 if (op0 != NULL || op1 != NULL)
2974 if (op0 == const1_rtx)
2975 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
2976 if (op1 == const1_rtx)
2977 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
2978 if (op0 == const0_rtx || op1 == const0_rtx)
2981 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
2982 else if (rtx_equal_p (x, op0))
2983 /* (x & A) & x ~ (x & A). */
2986 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
2987 else if (rtx_equal_p (x, op1))
2988 /* (A & x) & x ~ (A & x). */
2990 return gen_rtx_AND (0, op0, op1);
2994 return gen_rtx_AND (0, old, x);
2997 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
2999 return not_reg_cond (op0);
3002 return gen_rtx_AND (0, old, x);
3009 /* Given a condition X, remove references to reg REGNO and return the
3010 new condition. The removal will be done so that all conditions
3011 involving REGNO are considered to evaluate to false. This function
3012 is used when the value of REGNO changes. */
3015 elim_reg_cond (x, regno)
3021 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
3023 if (REGNO (XEXP (x, 0)) == regno)
3028 switch (GET_CODE (x))
3031 op0 = elim_reg_cond (XEXP (x, 0), regno);
3032 op1 = elim_reg_cond (XEXP (x, 1), regno);
3033 if (op0 == const0_rtx || op1 == const0_rtx)
3035 if (op0 == const1_rtx)
3037 if (op1 == const1_rtx)
3039 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3041 return gen_rtx_AND (0, op0, op1);
3044 op0 = elim_reg_cond (XEXP (x, 0), regno);
3045 op1 = elim_reg_cond (XEXP (x, 1), regno);
3046 if (op0 == const1_rtx || op1 == const1_rtx)
3048 if (op0 == const0_rtx)
3050 if (op1 == const0_rtx)
3052 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3054 return gen_rtx_IOR (0, op0, op1);
3057 op0 = elim_reg_cond (XEXP (x, 0), regno);
3058 if (op0 == const0_rtx)
3060 if (op0 == const1_rtx)
3062 if (op0 != XEXP (x, 0))
3063 return not_reg_cond (op0);
3070 #endif /* HAVE_conditional_execution */
3074 /* Try to substitute the auto-inc expression INC as the address inside
3075 MEM which occurs in INSN. Currently, the address of MEM is an expression
3076 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3077 that has a single set whose source is a PLUS of INCR_REG and something
3081 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
3082 struct propagate_block_info *pbi;
3083 rtx inc, insn, mem, incr, incr_reg;
3085 int regno = REGNO (incr_reg);
3086 rtx set = single_set (incr);
3087 rtx q = SET_DEST (set);
3088 rtx y = SET_SRC (set);
3089 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
3091 /* Make sure this reg appears only once in this insn. */
3092 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
3095 if (dead_or_set_p (incr, incr_reg)
3096 /* Mustn't autoinc an eliminable register. */
3097 && (regno >= FIRST_PSEUDO_REGISTER
3098 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
3100 /* This is the simple case. Try to make the auto-inc. If
3101 we can't, we are done. Otherwise, we will do any
3102 needed updates below. */
3103 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
3106 else if (GET_CODE (q) == REG
3107 /* PREV_INSN used here to check the semi-open interval
3109 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
3110 /* We must also check for sets of q as q may be
3111 a call clobbered hard register and there may
3112 be a call between PREV_INSN (insn) and incr. */
3113 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
3115 /* We have *p followed sometime later by q = p+size.
3116 Both p and q must be live afterward,
3117 and q is not used between INSN and its assignment.
3118 Change it to q = p, ...*q..., q = q+size.
3119 Then fall into the usual case. */
3123 emit_move_insn (q, incr_reg);
3124 insns = get_insns ();
3127 /* If we can't make the auto-inc, or can't make the
3128 replacement into Y, exit. There's no point in making
3129 the change below if we can't do the auto-inc and doing
3130 so is not correct in the pre-inc case. */
3133 validate_change (insn, &XEXP (mem, 0), inc, 1);
3134 validate_change (incr, &XEXP (y, opnum), q, 1);
3135 if (! apply_change_group ())
3138 /* We now know we'll be doing this change, so emit the
3139 new insn(s) and do the updates. */
3140 emit_insns_before (insns, insn);
3142 if (pbi->bb->head == insn)
3143 pbi->bb->head = insns;
3145 /* INCR will become a NOTE and INSN won't contain a
3146 use of INCR_REG. If a use of INCR_REG was just placed in
3147 the insn before INSN, make that the next use.
3148 Otherwise, invalidate it. */
3149 if (GET_CODE (PREV_INSN (insn)) == INSN
3150 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
3151 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
3152 pbi->reg_next_use[regno] = PREV_INSN (insn);
3154 pbi->reg_next_use[regno] = 0;
3159 /* REGNO is now used in INCR which is below INSN, but
3160 it previously wasn't live here. If we don't mark
3161 it as live, we'll put a REG_DEAD note for it
3162 on this insn, which is incorrect. */
3163 SET_REGNO_REG_SET (pbi->reg_live, regno);
3165 /* If there are any calls between INSN and INCR, show
3166 that REGNO now crosses them. */
3167 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
3168 if (GET_CODE (temp) == CALL_INSN)
3169 REG_N_CALLS_CROSSED (regno)++;
3171 /* Invalidate alias info for Q since we just changed its value. */
3172 clear_reg_alias_info (q);
3177 /* If we haven't returned, it means we were able to make the
3178 auto-inc, so update the status. First, record that this insn
3179 has an implicit side effect. */
3181 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
3183 /* Modify the old increment-insn to simply copy
3184 the already-incremented value of our register. */
3185 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
3188 /* If that makes it a no-op (copying the register into itself) delete
3189 it so it won't appear to be a "use" and a "set" of this
3191 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
3193 /* If the original source was dead, it's dead now. */
3196 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
3198 remove_note (incr, note);
3199 if (XEXP (note, 0) != incr_reg)
3200 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
3203 PUT_CODE (incr, NOTE);
3204 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
3205 NOTE_SOURCE_FILE (incr) = 0;
3208 if (regno >= FIRST_PSEUDO_REGISTER)
3210 /* Count an extra reference to the reg. When a reg is
3211 incremented, spilling it is worse, so we want to make
3212 that less likely. */
3213 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3215 /* Count the increment as a setting of the register,
3216 even though it isn't a SET in rtl. */
3217 REG_N_SETS (regno)++;
3221 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3225 find_auto_inc (pbi, x, insn)
3226 struct propagate_block_info *pbi;
3230 rtx addr = XEXP (x, 0);
3231 HOST_WIDE_INT offset = 0;
3232 rtx set, y, incr, inc_val;
3234 int size = GET_MODE_SIZE (GET_MODE (x));
3236 if (GET_CODE (insn) == JUMP_INSN)
3239 /* Here we detect use of an index register which might be good for
3240 postincrement, postdecrement, preincrement, or predecrement. */
3242 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
3243 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
3245 if (GET_CODE (addr) != REG)
3248 regno = REGNO (addr);
3250 /* Is the next use an increment that might make auto-increment? */
3251 incr = pbi->reg_next_use[regno];
3252 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
3254 set = single_set (incr);
3255 if (set == 0 || GET_CODE (set) != SET)
3259 if (GET_CODE (y) != PLUS)
3262 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
3263 inc_val = XEXP (y, 1);
3264 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
3265 inc_val = XEXP (y, 0);
3269 if (GET_CODE (inc_val) == CONST_INT)
3271 if (HAVE_POST_INCREMENT
3272 && (INTVAL (inc_val) == size && offset == 0))
3273 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
3275 else if (HAVE_POST_DECREMENT
3276 && (INTVAL (inc_val) == -size && offset == 0))
3277 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
3279 else if (HAVE_PRE_INCREMENT
3280 && (INTVAL (inc_val) == size && offset == size))
3281 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
3283 else if (HAVE_PRE_DECREMENT
3284 && (INTVAL (inc_val) == -size && offset == -size))
3285 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
3287 else if (HAVE_POST_MODIFY_DISP && offset == 0)
3288 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3289 gen_rtx_PLUS (Pmode,
3292 insn, x, incr, addr);
3294 else if (GET_CODE (inc_val) == REG
3295 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
3299 if (HAVE_POST_MODIFY_REG && offset == 0)
3300 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3301 gen_rtx_PLUS (Pmode,
3304 insn, x, incr, addr);
3308 #endif /* AUTO_INC_DEC */
3311 mark_used_reg (pbi, reg, cond, insn)
3312 struct propagate_block_info *pbi;
3314 rtx cond ATTRIBUTE_UNUSED;
3317 unsigned int regno_first, regno_last, i;
3318 int some_was_live, some_was_dead, some_not_set;
3320 regno_last = regno_first = REGNO (reg);
3321 if (regno_first < FIRST_PSEUDO_REGISTER)
3322 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
3324 /* Find out if any of this register is live after this instruction. */
3325 some_was_live = some_was_dead = 0;
3326 for (i = regno_first; i <= regno_last; ++i)
3328 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
3329 some_was_live |= needed_regno;
3330 some_was_dead |= ! needed_regno;
3333 /* Find out if any of the register was set this insn. */
3335 for (i = regno_first; i <= regno_last; ++i)
3336 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
3338 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3340 /* Record where each reg is used, so when the reg is set we know
3341 the next insn that uses it. */
3342 pbi->reg_next_use[regno_first] = insn;
3345 if (pbi->flags & PROP_REG_INFO)
3347 if (regno_first < FIRST_PSEUDO_REGISTER)
3349 /* If this is a register we are going to try to eliminate,
3350 don't mark it live here. If we are successful in
3351 eliminating it, it need not be live unless it is used for
3352 pseudos, in which case it will have been set live when it
3353 was allocated to the pseudos. If the register will not
3354 be eliminated, reload will set it live at that point.
3356 Otherwise, record that this function uses this register. */
3357 /* ??? The PPC backend tries to "eliminate" on the pic
3358 register to itself. This should be fixed. In the mean
3359 time, hack around it. */
3361 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
3362 && (regno_first == FRAME_POINTER_REGNUM
3363 || regno_first == ARG_POINTER_REGNUM)))
3364 for (i = regno_first; i <= regno_last; ++i)
3365 regs_ever_live[i] = 1;
3369 /* Keep track of which basic block each reg appears in. */
3371 int blocknum = pbi->bb->index;
3372 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
3373 REG_BASIC_BLOCK (regno_first) = blocknum;
3374 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
3375 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
3377 /* Count (weighted) number of uses of each reg. */
3378 REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb);
3379 REG_N_REFS (regno_first)++;
3383 /* Record and count the insns in which a reg dies. If it is used in
3384 this insn and was dead below the insn then it dies in this insn.
3385 If it was set in this insn, we do not make a REG_DEAD note;
3386 likewise if we already made such a note. */
3387 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
3391 /* Check for the case where the register dying partially
3392 overlaps the register set by this insn. */
3393 if (regno_first != regno_last)
3394 for (i = regno_first; i <= regno_last; ++i)
3395 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
3397 /* If none of the words in X is needed, make a REG_DEAD note.
3398 Otherwise, we must make partial REG_DEAD notes. */
3399 if (! some_was_live)
3401 if ((pbi->flags & PROP_DEATH_NOTES)
3402 && ! find_regno_note (insn, REG_DEAD, regno_first))
3404 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
3406 if (pbi->flags & PROP_REG_INFO)
3407 REG_N_DEATHS (regno_first)++;
3411 /* Don't make a REG_DEAD note for a part of a register
3412 that is set in the insn. */
3413 for (i = regno_first; i <= regno_last; ++i)
3414 if (! REGNO_REG_SET_P (pbi->reg_live, i)
3415 && ! dead_or_set_regno_p (insn, i))
3417 = alloc_EXPR_LIST (REG_DEAD,
3418 gen_rtx_REG (reg_raw_mode[i], i),
3423 /* Mark the register as being live. */
3424 for (i = regno_first; i <= regno_last; ++i)
3426 SET_REGNO_REG_SET (pbi->reg_live, i);
3428 #ifdef HAVE_conditional_execution
3429 /* If this is a conditional use, record that fact. If it is later
3430 conditionally set, we'll know to kill the register. */
3431 if (cond != NULL_RTX)
3433 splay_tree_node node;
3434 struct reg_cond_life_info *rcli;
3439 node = splay_tree_lookup (pbi->reg_cond_dead, i);
3442 /* The register was unconditionally live previously.
3443 No need to do anything. */
3447 /* The register was conditionally live previously.
3448 Subtract the new life cond from the old death cond. */
3449 rcli = (struct reg_cond_life_info *) node->value;
3450 ncond = rcli->condition;
3451 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
3453 /* If the register is now unconditionally live,
3454 remove the entry in the splay_tree. */
3455 if (ncond == const0_rtx)
3456 splay_tree_remove (pbi->reg_cond_dead, i);
3459 rcli->condition = ncond;
3460 SET_REGNO_REG_SET (pbi->reg_cond_reg,
3461 REGNO (XEXP (cond, 0)));
3467 /* The register was not previously live at all. Record
3468 the condition under which it is still dead. */
3469 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
3470 rcli->condition = not_reg_cond (cond);
3471 rcli->stores = const0_rtx;
3472 rcli->orig_condition = const0_rtx;
3473 splay_tree_insert (pbi->reg_cond_dead, i,
3474 (splay_tree_value) rcli);
3476 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
3479 else if (some_was_live)
3481 /* The register may have been conditionally live previously, but
3482 is now unconditionally live. Remove it from the conditionally
3483 dead list, so that a conditional set won't cause us to think
3485 splay_tree_remove (pbi->reg_cond_dead, i);
3491 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3492 This is done assuming the registers needed from X are those that
3493 have 1-bits in PBI->REG_LIVE.
3495 INSN is the containing instruction. If INSN is dead, this function
3499 mark_used_regs (pbi, x, cond, insn)
3500 struct propagate_block_info *pbi;
3505 int flags = pbi->flags;
3508 code = GET_CODE (x);
3528 /* If we are clobbering a MEM, mark any registers inside the address
3530 if (GET_CODE (XEXP (x, 0)) == MEM)
3531 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
3535 /* Don't bother watching stores to mems if this is not the
3536 final pass. We'll not be deleting dead stores this round. */
3537 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
3539 /* Invalidate the data for the last MEM stored, but only if MEM is
3540 something that can be stored into. */
3541 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3542 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3543 /* Needn't clear the memory set list. */
3547 rtx temp = pbi->mem_set_list;
3548 rtx prev = NULL_RTX;
3553 next = XEXP (temp, 1);
3554 if (anti_dependence (XEXP (temp, 0), x))
3556 /* Splice temp out of the list. */
3558 XEXP (prev, 1) = next;
3560 pbi->mem_set_list = next;
3561 free_EXPR_LIST_node (temp);
3562 pbi->mem_set_list_len--;
3570 /* If the memory reference had embedded side effects (autoincrement
3571 address modes. Then we may need to kill some entries on the
3574 invalidate_mems_from_autoinc (pbi, insn);
3578 if (flags & PROP_AUTOINC)
3579 find_auto_inc (pbi, x, insn);
3584 #ifdef CLASS_CANNOT_CHANGE_MODE
3585 if (GET_CODE (SUBREG_REG (x)) == REG
3586 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
3587 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
3588 GET_MODE (SUBREG_REG (x))))
3589 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
3592 /* While we're here, optimize this case. */
3594 if (GET_CODE (x) != REG)
3599 /* See a register other than being set => mark it as needed. */
3600 mark_used_reg (pbi, x, cond, insn);
3605 rtx testreg = SET_DEST (x);
3608 /* If storing into MEM, don't show it as being used. But do
3609 show the address as being used. */
3610 if (GET_CODE (testreg) == MEM)
3613 if (flags & PROP_AUTOINC)
3614 find_auto_inc (pbi, testreg, insn);
3616 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
3617 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3621 /* Storing in STRICT_LOW_PART is like storing in a reg
3622 in that this SET might be dead, so ignore it in TESTREG.
3623 but in some other ways it is like using the reg.
3625 Storing in a SUBREG or a bit field is like storing the entire
3626 register in that if the register's value is not used
3627 then this SET is not needed. */
3628 while (GET_CODE (testreg) == STRICT_LOW_PART
3629 || GET_CODE (testreg) == ZERO_EXTRACT
3630 || GET_CODE (testreg) == SIGN_EXTRACT
3631 || GET_CODE (testreg) == SUBREG)
3633 #ifdef CLASS_CANNOT_CHANGE_MODE
3634 if (GET_CODE (testreg) == SUBREG
3635 && GET_CODE (SUBREG_REG (testreg)) == REG
3636 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
3637 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
3638 GET_MODE (testreg)))
3639 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
3642 /* Modifying a single register in an alternate mode
3643 does not use any of the old value. But these other
3644 ways of storing in a register do use the old value. */
3645 if (GET_CODE (testreg) == SUBREG
3646 && !((REG_BYTES (SUBREG_REG (testreg))
3647 + UNITS_PER_WORD - 1) / UNITS_PER_WORD
3648 > (REG_BYTES (testreg)
3649 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
3654 testreg = XEXP (testreg, 0);
3657 /* If this is a store into a register or group of registers,
3658 recursively scan the value being stored. */
3660 if ((GET_CODE (testreg) == PARALLEL
3661 && GET_MODE (testreg) == BLKmode)
3662 || (GET_CODE (testreg) == REG
3663 && (regno = REGNO (testreg),
3664 ! (regno == FRAME_POINTER_REGNUM
3665 && (! reload_completed || frame_pointer_needed)))
3666 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3667 && ! (regno == HARD_FRAME_POINTER_REGNUM
3668 && (! reload_completed || frame_pointer_needed))
3670 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3671 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
3676 mark_used_regs (pbi, SET_DEST (x), cond, insn);
3677 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3684 case UNSPEC_VOLATILE:
3688 /* Traditional and volatile asm instructions must be considered to use
3689 and clobber all hard registers, all pseudo-registers and all of
3690 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3692 Consider for instance a volatile asm that changes the fpu rounding
3693 mode. An insn should not be moved across this even if it only uses
3694 pseudo-regs because it might give an incorrectly rounded result.
3696 ?!? Unfortunately, marking all hard registers as live causes massive
3697 problems for the register allocator and marking all pseudos as live
3698 creates mountains of uninitialized variable warnings.
3700 So for now, just clear the memory set list and mark any regs
3701 we can find in ASM_OPERANDS as used. */
3702 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
3704 free_EXPR_LIST_list (&pbi->mem_set_list);
3705 pbi->mem_set_list_len = 0;
3708 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3709 We can not just fall through here since then we would be confused
3710 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3711 traditional asms unlike their normal usage. */
3712 if (code == ASM_OPERANDS)
3716 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
3717 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
3723 if (cond != NULL_RTX)
3726 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
3728 cond = COND_EXEC_TEST (x);
3729 x = COND_EXEC_CODE (x);
3733 /* We _do_not_ want to scan operands of phi nodes. Operands of
3734 a phi function are evaluated only when control reaches this
3735 block along a particular edge. Therefore, regs that appear
3736 as arguments to phi should not be added to the global live at
3744 /* Recursively scan the operands of this expression. */
3747 const char * const fmt = GET_RTX_FORMAT (code);
3750 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3754 /* Tail recursive case: save a function call level. */
3760 mark_used_regs (pbi, XEXP (x, i), cond, insn);
3762 else if (fmt[i] == 'E')
3765 for (j = 0; j < XVECLEN (x, i); j++)
3766 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
3775 try_pre_increment_1 (pbi, insn)
3776 struct propagate_block_info *pbi;
3779 /* Find the next use of this reg. If in same basic block,
3780 make it do pre-increment or pre-decrement if appropriate. */
3781 rtx x = single_set (insn);
3782 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
3783 * INTVAL (XEXP (SET_SRC (x), 1)));
3784 int regno = REGNO (SET_DEST (x));
3785 rtx y = pbi->reg_next_use[regno];
3787 && SET_DEST (x) != stack_pointer_rtx
3788 && BLOCK_NUM (y) == BLOCK_NUM (insn)
3789 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3790 mode would be better. */
3791 && ! dead_or_set_p (y, SET_DEST (x))
3792 && try_pre_increment (y, SET_DEST (x), amount))
3794 /* We have found a suitable auto-increment and already changed
3795 insn Y to do it. So flush this increment instruction. */
3796 propagate_block_delete_insn (pbi->bb, insn);
3798 /* Count a reference to this reg for the increment insn we are
3799 deleting. When a reg is incremented, spilling it is worse,
3800 so we want to make that less likely. */
3801 if (regno >= FIRST_PSEUDO_REGISTER)
3803 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3804 REG_N_SETS (regno)++;
3807 /* Flush any remembered memories depending on the value of
3808 the incremented register. */
3809 invalidate_mems_from_set (pbi, SET_DEST (x));
3816 /* Try to change INSN so that it does pre-increment or pre-decrement
3817 addressing on register REG in order to add AMOUNT to REG.
3818 AMOUNT is negative for pre-decrement.
3819 Returns 1 if the change could be made.
3820 This checks all about the validity of the result of modifying INSN. */
3823 try_pre_increment (insn, reg, amount)
3825 HOST_WIDE_INT amount;
3829 /* Nonzero if we can try to make a pre-increment or pre-decrement.
3830 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
3832 /* Nonzero if we can try to make a post-increment or post-decrement.
3833 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
3834 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
3835 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
3838 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
3841 /* From the sign of increment, see which possibilities are conceivable
3842 on this target machine. */
3843 if (HAVE_PRE_INCREMENT && amount > 0)
3845 if (HAVE_POST_INCREMENT && amount > 0)
3848 if (HAVE_PRE_DECREMENT && amount < 0)
3850 if (HAVE_POST_DECREMENT && amount < 0)
3853 if (! (pre_ok || post_ok))
3856 /* It is not safe to add a side effect to a jump insn
3857 because if the incremented register is spilled and must be reloaded
3858 there would be no way to store the incremented value back in memory. */
3860 if (GET_CODE (insn) == JUMP_INSN)
3865 use = find_use_as_address (PATTERN (insn), reg, 0);
3866 if (post_ok && (use == 0 || use == (rtx) 1))
3868 use = find_use_as_address (PATTERN (insn), reg, -amount);
3872 if (use == 0 || use == (rtx) 1)
3875 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
3878 /* See if this combination of instruction and addressing mode exists. */
3879 if (! validate_change (insn, &XEXP (use, 0),
3880 gen_rtx_fmt_e (amount > 0
3881 ? (do_post ? POST_INC : PRE_INC)
3882 : (do_post ? POST_DEC : PRE_DEC),
3886 /* Record that this insn now has an implicit side effect on X. */
3887 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
3891 #endif /* AUTO_INC_DEC */
3893 /* Find the place in the rtx X where REG is used as a memory address.
3894 Return the MEM rtx that so uses it.
3895 If PLUSCONST is nonzero, search instead for a memory address equivalent to
3896 (plus REG (const_int PLUSCONST)).
3898 If such an address does not appear, return 0.
3899 If REG appears more than once, or is used other than in such an address,
3903 find_use_as_address (x, reg, plusconst)
3906 HOST_WIDE_INT plusconst;
3908 enum rtx_code code = GET_CODE (x);
3909 const char * const fmt = GET_RTX_FORMAT (code);
3914 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
3917 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
3918 && XEXP (XEXP (x, 0), 0) == reg
3919 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
3920 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
3923 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
3925 /* If REG occurs inside a MEM used in a bit-field reference,
3926 that is unacceptable. */
3927 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
3928 return (rtx) (HOST_WIDE_INT) 1;
3932 return (rtx) (HOST_WIDE_INT) 1;
3934 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3938 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
3942 return (rtx) (HOST_WIDE_INT) 1;
3944 else if (fmt[i] == 'E')
3947 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
3949 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
3953 return (rtx) (HOST_WIDE_INT) 1;
3961 /* Write information about registers and basic blocks into FILE.
3962 This is part of making a debugging dump. */
3965 dump_regset (r, outf)
3972 fputs (" (nil)", outf);
3976 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
3978 fprintf (outf, " %d", i);
3979 if (i < FIRST_PSEUDO_REGISTER)
3980 fprintf (outf, " [%s]",
3985 /* Print a human-reaable representation of R on the standard error
3986 stream. This function is designed to be used from within the
3993 dump_regset (r, stderr);
3994 putc ('\n', stderr);
3997 /* Dump the rtl into the current debugging dump file, then abort. */
4000 print_rtl_and_abort_fcn (file, line, function)
4003 const char *function;
4007 print_rtl_with_bb (rtl_dump_file, get_insns ());
4008 fclose (rtl_dump_file);
4011 fancy_abort (file, line, function);
4014 /* Recompute register set/reference counts immediately prior to register
4017 This avoids problems with set/reference counts changing to/from values
4018 which have special meanings to the register allocators.
4020 Additionally, the reference counts are the primary component used by the
4021 register allocators to prioritize pseudos for allocation to hard regs.
4022 More accurate reference counts generally lead to better register allocation.
4024 F is the first insn to be scanned.
4026 LOOP_STEP denotes how much loop_depth should be incremented per
4027 loop nesting level in order to increase the ref count more for
4028 references in a loop.
4030 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4031 possibly other information which is used by the register allocators. */
4034 recompute_reg_usage (f, loop_step)
4035 rtx f ATTRIBUTE_UNUSED;
4036 int loop_step ATTRIBUTE_UNUSED;
4038 allocate_reg_life_data ();
4039 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
4042 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4043 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4044 of the number of registers that died. */
4047 count_or_remove_death_notes (blocks, kill)
4053 for (i = n_basic_blocks - 1; i >= 0; --i)
4058 if (blocks && ! TEST_BIT (blocks, i))
4061 bb = BASIC_BLOCK (i);
4063 for (insn = bb->head;; insn = NEXT_INSN (insn))
4067 rtx *pprev = ®_NOTES (insn);
4072 switch (REG_NOTE_KIND (link))
4075 if (GET_CODE (XEXP (link, 0)) == REG)
4077 rtx reg = XEXP (link, 0);
4080 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
4083 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
4091 rtx next = XEXP (link, 1);
4092 free_EXPR_LIST_node (link);
4093 *pprev = link = next;
4099 pprev = &XEXP (link, 1);
4106 if (insn == bb->end)
4113 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4114 if blocks is NULL. */
4117 clear_log_links (blocks)
4125 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4127 free_INSN_LIST_list (&LOG_LINKS (insn));
4130 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4132 basic_block bb = BASIC_BLOCK (i);
4134 for (insn = bb->head; insn != NEXT_INSN (bb->end);
4135 insn = NEXT_INSN (insn))
4137 free_INSN_LIST_list (&LOG_LINKS (insn));
4141 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4142 correspond to the hard registers, if any, set in that map. This
4143 could be done far more efficiently by having all sorts of special-cases
4144 with moving single words, but probably isn't worth the trouble. */
4147 reg_set_to_hard_reg_set (to, from)
4153 EXECUTE_IF_SET_IN_BITMAP
4156 if (i >= FIRST_PSEUDO_REGISTER)
4158 SET_HARD_REG_BIT (*to, i);