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 preceeding
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 /* If flow is invoked after reload, we must take existing AUTO_INC
1896 expresions into account. */
1897 if (reload_completed)
1899 for (; notes; notes = XEXP (notes, 1))
1901 if (REG_NOTE_KIND (notes) == REG_INC)
1903 int regno = REGNO (XEXP (notes, 0));
1905 /* Don't delete insns to set global regs. */
1906 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
1907 || REGNO_REG_SET_P (pbi->reg_live, regno))
1914 /* If setting something that's a reg or part of one,
1915 see if that register's altered value will be live. */
1919 rtx r = SET_DEST (x);
1922 if (GET_CODE (r) == CC0)
1923 return ! pbi->cc0_live;
1926 /* A SET that is a subroutine call cannot be dead. */
1927 if (GET_CODE (SET_SRC (x)) == CALL)
1933 /* Don't eliminate loads from volatile memory or volatile asms. */
1934 else if (volatile_refs_p (SET_SRC (x)))
1937 if (GET_CODE (r) == MEM)
1941 if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode)
1944 canon_r = canon_rtx (r);
1946 /* Walk the set of memory locations we are currently tracking
1947 and see if one is an identical match to this memory location.
1948 If so, this memory write is dead (remember, we're walking
1949 backwards from the end of the block to the start). Since
1950 rtx_equal_p does not check the alias set or flags, we also
1951 must have the potential for them to conflict (anti_dependence). */
1952 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
1953 if (anti_dependence (r, XEXP (temp, 0)))
1955 rtx mem = XEXP (temp, 0);
1957 if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0))
1958 && (GET_MODE_SIZE (GET_MODE (canon_r))
1959 <= GET_MODE_SIZE (GET_MODE (mem))))
1963 /* Check if memory reference matches an auto increment. Only
1964 post increment/decrement or modify are valid. */
1965 if (GET_MODE (mem) == GET_MODE (r)
1966 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
1967 || GET_CODE (XEXP (mem, 0)) == POST_INC
1968 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
1969 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
1970 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
1977 while (GET_CODE (r) == SUBREG
1978 || GET_CODE (r) == STRICT_LOW_PART
1979 || GET_CODE (r) == ZERO_EXTRACT)
1982 if (GET_CODE (r) == REG)
1984 int regno = REGNO (r);
1987 if (REGNO_REG_SET_P (pbi->reg_live, regno))
1990 /* If this is a hard register, verify that subsequent
1991 words are not needed. */
1992 if (regno < FIRST_PSEUDO_REGISTER)
1994 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
1997 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
2001 /* Don't delete insns to set global regs. */
2002 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2005 /* Make sure insns to set the stack pointer aren't deleted. */
2006 if (regno == STACK_POINTER_REGNUM)
2009 /* ??? These bits might be redundant with the force live bits
2010 in calculate_global_regs_live. We would delete from
2011 sequential sets; whether this actually affects real code
2012 for anything but the stack pointer I don't know. */
2013 /* Make sure insns to set the frame pointer aren't deleted. */
2014 if (regno == FRAME_POINTER_REGNUM
2015 && (! reload_completed || frame_pointer_needed))
2017 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2018 if (regno == HARD_FRAME_POINTER_REGNUM
2019 && (! reload_completed || frame_pointer_needed))
2023 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2024 /* Make sure insns to set arg pointer are never deleted
2025 (if the arg pointer isn't fixed, there will be a USE
2026 for it, so we can treat it normally). */
2027 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2031 /* Otherwise, the set is dead. */
2037 /* If performing several activities, insn is dead if each activity
2038 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2039 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2041 else if (code == PARALLEL)
2043 int i = XVECLEN (x, 0);
2045 for (i--; i >= 0; i--)
2046 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
2047 && GET_CODE (XVECEXP (x, 0, i)) != USE
2048 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
2054 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2055 is not necessarily true for hard registers. */
2056 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
2057 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
2058 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
2061 /* We do not check other CLOBBER or USE here. An insn consisting of just
2062 a CLOBBER or just a USE should not be deleted. */
2066 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2067 return 1 if the entire library call is dead.
2068 This is true if INSN copies a register (hard or pseudo)
2069 and if the hard return reg of the call insn is dead.
2070 (The caller should have tested the destination of the SET inside
2071 INSN already for death.)
2073 If this insn doesn't just copy a register, then we don't
2074 have an ordinary libcall. In that case, cse could not have
2075 managed to substitute the source for the dest later on,
2076 so we can assume the libcall is dead.
2078 PBI is the block info giving pseudoregs live before this insn.
2079 NOTE is the REG_RETVAL note of the insn. */
2082 libcall_dead_p (pbi, note, insn)
2083 struct propagate_block_info *pbi;
2087 rtx x = single_set (insn);
2091 rtx r = SET_SRC (x);
2093 if (GET_CODE (r) == REG)
2095 rtx call = XEXP (note, 0);
2099 /* Find the call insn. */
2100 while (call != insn && GET_CODE (call) != CALL_INSN)
2101 call = NEXT_INSN (call);
2103 /* If there is none, do nothing special,
2104 since ordinary death handling can understand these insns. */
2108 /* See if the hard reg holding the value is dead.
2109 If this is a PARALLEL, find the call within it. */
2110 call_pat = PATTERN (call);
2111 if (GET_CODE (call_pat) == PARALLEL)
2113 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
2114 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
2115 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
2118 /* This may be a library call that is returning a value
2119 via invisible pointer. Do nothing special, since
2120 ordinary death handling can understand these insns. */
2124 call_pat = XVECEXP (call_pat, 0, i);
2127 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
2133 /* Return 1 if register REGNO was used before it was set, i.e. if it is
2134 live at function entry. Don't count global register variables, variables
2135 in registers that can be used for function arg passing, or variables in
2136 fixed hard registers. */
2139 regno_uninitialized (regno)
2142 if (n_basic_blocks == 0
2143 || (regno < FIRST_PSEUDO_REGISTER
2144 && (global_regs[regno]
2145 || fixed_regs[regno]
2146 || FUNCTION_ARG_REGNO_P (regno))))
2149 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
2152 /* 1 if register REGNO was alive at a place where `setjmp' was called
2153 and was set more than once or is an argument.
2154 Such regs may be clobbered by `longjmp'. */
2157 regno_clobbered_at_setjmp (regno)
2160 if (n_basic_blocks == 0)
2163 return ((REG_N_SETS (regno) > 1
2164 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
2165 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
2168 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2169 maximal list size; look for overlaps in mode and select the largest. */
2171 add_to_mem_set_list (pbi, mem)
2172 struct propagate_block_info *pbi;
2177 /* We don't know how large a BLKmode store is, so we must not
2178 take them into consideration. */
2179 if (GET_MODE (mem) == BLKmode)
2182 for (i = pbi->mem_set_list; i ; i = XEXP (i, 1))
2184 rtx e = XEXP (i, 0);
2185 if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0)))
2187 if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e)))
2190 /* If we must store a copy of the mem, we can just modify
2191 the mode of the stored copy. */
2192 if (pbi->flags & PROP_AUTOINC)
2193 PUT_MODE (e, GET_MODE (mem));
2202 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN)
2205 /* Store a copy of mem, otherwise the address may be
2206 scrogged by find_auto_inc. */
2207 if (pbi->flags & PROP_AUTOINC)
2208 mem = shallow_copy_rtx (mem);
2210 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
2211 pbi->mem_set_list_len++;
2215 /* INSN references memory, possibly using autoincrement addressing modes.
2216 Find any entries on the mem_set_list that need to be invalidated due
2217 to an address change. */
2220 invalidate_mems_from_autoinc (pbi, insn)
2221 struct propagate_block_info *pbi;
2224 rtx note = REG_NOTES (insn);
2225 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
2226 if (REG_NOTE_KIND (note) == REG_INC)
2227 invalidate_mems_from_set (pbi, XEXP (note, 0));
2230 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2233 invalidate_mems_from_set (pbi, exp)
2234 struct propagate_block_info *pbi;
2237 rtx temp = pbi->mem_set_list;
2238 rtx prev = NULL_RTX;
2243 next = XEXP (temp, 1);
2244 if (reg_overlap_mentioned_p (exp, XEXP (temp, 0)))
2246 /* Splice this entry out of the list. */
2248 XEXP (prev, 1) = next;
2250 pbi->mem_set_list = next;
2251 free_EXPR_LIST_node (temp);
2252 pbi->mem_set_list_len--;
2260 /* Process the registers that are set within X. Their bits are set to
2261 1 in the regset DEAD, because they are dead prior to this insn.
2263 If INSN is nonzero, it is the insn being processed.
2265 FLAGS is the set of operations to perform. */
2268 mark_set_regs (pbi, x, insn)
2269 struct propagate_block_info *pbi;
2272 rtx cond = NULL_RTX;
2277 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2279 if (REG_NOTE_KIND (link) == REG_INC)
2280 mark_set_1 (pbi, SET, XEXP (link, 0),
2281 (GET_CODE (x) == COND_EXEC
2282 ? COND_EXEC_TEST (x) : NULL_RTX),
2286 switch (code = GET_CODE (x))
2290 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
2294 cond = COND_EXEC_TEST (x);
2295 x = COND_EXEC_CODE (x);
2302 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2304 rtx sub = XVECEXP (x, 0, i);
2305 switch (code = GET_CODE (sub))
2308 if (cond != NULL_RTX)
2311 cond = COND_EXEC_TEST (sub);
2312 sub = COND_EXEC_CODE (sub);
2313 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
2319 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
2334 /* Process a single set, which appears in INSN. REG (which may not
2335 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2336 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2337 If the set is conditional (because it appear in a COND_EXEC), COND
2338 will be the condition. */
2341 mark_set_1 (pbi, code, reg, cond, insn, flags)
2342 struct propagate_block_info *pbi;
2344 rtx reg, cond, insn;
2347 int regno_first = -1, regno_last = -1;
2348 unsigned long not_dead = 0;
2351 /* Modifying just one hardware register of a multi-reg value or just a
2352 byte field of a register does not mean the value from before this insn
2353 is now dead. Of course, if it was dead after it's unused now. */
2355 switch (GET_CODE (reg))
2358 /* Some targets place small structures in registers for return values of
2359 functions. We have to detect this case specially here to get correct
2360 flow information. */
2361 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
2362 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
2363 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
2369 case STRICT_LOW_PART:
2370 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2372 reg = XEXP (reg, 0);
2373 while (GET_CODE (reg) == SUBREG
2374 || GET_CODE (reg) == ZERO_EXTRACT
2375 || GET_CODE (reg) == SIGN_EXTRACT
2376 || GET_CODE (reg) == STRICT_LOW_PART);
2377 if (GET_CODE (reg) == MEM)
2379 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
2383 regno_last = regno_first = REGNO (reg);
2384 if (regno_first < FIRST_PSEUDO_REGISTER)
2385 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
2389 if (GET_CODE (SUBREG_REG (reg)) == REG)
2391 enum machine_mode outer_mode = GET_MODE (reg);
2392 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
2394 /* Identify the range of registers affected. This is moderately
2395 tricky for hard registers. See alter_subreg. */
2397 regno_last = regno_first = REGNO (SUBREG_REG (reg));
2398 if (regno_first < FIRST_PSEUDO_REGISTER)
2400 regno_first += subreg_regno_offset (regno_first, inner_mode,
2403 regno_last = (regno_first
2404 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
2406 /* Since we've just adjusted the register number ranges, make
2407 sure REG matches. Otherwise some_was_live will be clear
2408 when it shouldn't have been, and we'll create incorrect
2409 REG_UNUSED notes. */
2410 reg = gen_rtx_REG (outer_mode, regno_first);
2414 /* If the number of words in the subreg is less than the number
2415 of words in the full register, we have a well-defined partial
2416 set. Otherwise the high bits are undefined.
2418 This is only really applicable to pseudos, since we just took
2419 care of multi-word hard registers. */
2420 if (((GET_MODE_SIZE (outer_mode)
2421 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
2422 < ((GET_MODE_SIZE (inner_mode)
2423 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
2424 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
2427 reg = SUBREG_REG (reg);
2431 reg = SUBREG_REG (reg);
2438 /* If this set is a MEM, then it kills any aliased writes.
2439 If this set is a REG, then it kills any MEMs which use the reg. */
2440 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2442 if (GET_CODE (reg) == REG)
2443 invalidate_mems_from_set (pbi, reg);
2445 /* If the memory reference had embedded side effects (autoincrement
2446 address modes. Then we may need to kill some entries on the
2448 if (insn && GET_CODE (reg) == MEM)
2449 invalidate_mems_from_autoinc (pbi, insn);
2451 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
2452 /* ??? With more effort we could track conditional memory life. */
2454 /* There are no REG_INC notes for SP, so we can't assume we'll see
2455 everything that invalidates it. To be safe, don't eliminate any
2456 stores though SP; none of them should be redundant anyway. */
2457 && ! reg_mentioned_p (stack_pointer_rtx, reg))
2458 add_to_mem_set_list (pbi, canon_rtx (reg));
2461 if (GET_CODE (reg) == REG
2462 && ! (regno_first == FRAME_POINTER_REGNUM
2463 && (! reload_completed || frame_pointer_needed))
2464 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2465 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
2466 && (! reload_completed || frame_pointer_needed))
2468 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2469 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
2473 int some_was_live = 0, some_was_dead = 0;
2475 for (i = regno_first; i <= regno_last; ++i)
2477 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
2480 /* Order of the set operation matters here since both
2481 sets may be the same. */
2482 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
2483 if (cond != NULL_RTX
2484 && ! REGNO_REG_SET_P (pbi->local_set, i))
2485 SET_REGNO_REG_SET (pbi->cond_local_set, i);
2487 SET_REGNO_REG_SET (pbi->local_set, i);
2489 if (code != CLOBBER)
2490 SET_REGNO_REG_SET (pbi->new_set, i);
2492 some_was_live |= needed_regno;
2493 some_was_dead |= ! needed_regno;
2496 #ifdef HAVE_conditional_execution
2497 /* Consider conditional death in deciding that the register needs
2499 if (some_was_live && ! not_dead
2500 /* The stack pointer is never dead. Well, not strictly true,
2501 but it's very difficult to tell from here. Hopefully
2502 combine_stack_adjustments will fix up the most egregious
2504 && regno_first != STACK_POINTER_REGNUM)
2506 for (i = regno_first; i <= regno_last; ++i)
2507 if (! mark_regno_cond_dead (pbi, i, cond))
2508 not_dead |= ((unsigned long) 1) << (i - regno_first);
2512 /* Additional data to record if this is the final pass. */
2513 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
2514 | PROP_DEATH_NOTES | PROP_AUTOINC))
2517 int blocknum = pbi->bb->index;
2520 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2522 y = pbi->reg_next_use[regno_first];
2524 /* The next use is no longer next, since a store intervenes. */
2525 for (i = regno_first; i <= regno_last; ++i)
2526 pbi->reg_next_use[i] = 0;
2529 if (flags & PROP_REG_INFO)
2531 for (i = regno_first; i <= regno_last; ++i)
2533 /* Count (weighted) references, stores, etc. This counts a
2534 register twice if it is modified, but that is correct. */
2535 REG_N_SETS (i) += 1;
2536 REG_N_REFS (i) += 1;
2537 REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb);
2539 /* The insns where a reg is live are normally counted
2540 elsewhere, but we want the count to include the insn
2541 where the reg is set, and the normal counting mechanism
2542 would not count it. */
2543 REG_LIVE_LENGTH (i) += 1;
2546 /* If this is a hard reg, record this function uses the reg. */
2547 if (regno_first < FIRST_PSEUDO_REGISTER)
2549 for (i = regno_first; i <= regno_last; i++)
2550 regs_ever_live[i] = 1;
2554 /* Keep track of which basic blocks each reg appears in. */
2555 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
2556 REG_BASIC_BLOCK (regno_first) = blocknum;
2557 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
2558 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
2562 if (! some_was_dead)
2564 if (flags & PROP_LOG_LINKS)
2566 /* Make a logical link from the next following insn
2567 that uses this register, back to this insn.
2568 The following insns have already been processed.
2570 We don't build a LOG_LINK for hard registers containing
2571 in ASM_OPERANDs. If these registers get replaced,
2572 we might wind up changing the semantics of the insn,
2573 even if reload can make what appear to be valid
2574 assignments later. */
2575 if (y && (BLOCK_NUM (y) == blocknum)
2576 && (regno_first >= FIRST_PSEUDO_REGISTER
2577 || asm_noperands (PATTERN (y)) < 0))
2578 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
2583 else if (! some_was_live)
2585 if (flags & PROP_REG_INFO)
2586 REG_N_DEATHS (regno_first) += 1;
2588 if (flags & PROP_DEATH_NOTES)
2590 /* Note that dead stores have already been deleted
2591 when possible. If we get here, we have found a
2592 dead store that cannot be eliminated (because the
2593 same insn does something useful). Indicate this
2594 by marking the reg being set as dying here. */
2596 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2601 if (flags & PROP_DEATH_NOTES)
2603 /* This is a case where we have a multi-word hard register
2604 and some, but not all, of the words of the register are
2605 needed in subsequent insns. Write REG_UNUSED notes
2606 for those parts that were not needed. This case should
2609 for (i = regno_first; i <= regno_last; ++i)
2610 if (! REGNO_REG_SET_P (pbi->reg_live, i))
2612 = alloc_EXPR_LIST (REG_UNUSED,
2613 gen_rtx_REG (reg_raw_mode[i], i),
2619 /* Mark the register as being dead. */
2621 /* The stack pointer is never dead. Well, not strictly true,
2622 but it's very difficult to tell from here. Hopefully
2623 combine_stack_adjustments will fix up the most egregious
2625 && regno_first != STACK_POINTER_REGNUM)
2627 for (i = regno_first; i <= regno_last; ++i)
2628 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
2629 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
2632 else if (GET_CODE (reg) == REG)
2634 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2635 pbi->reg_next_use[regno_first] = 0;
2638 /* If this is the last pass and this is a SCRATCH, show it will be dying
2639 here and count it. */
2640 else if (GET_CODE (reg) == SCRATCH)
2642 if (flags & PROP_DEATH_NOTES)
2644 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2648 #ifdef HAVE_conditional_execution
2649 /* Mark REGNO conditionally dead.
2650 Return true if the register is now unconditionally dead. */
2653 mark_regno_cond_dead (pbi, regno, cond)
2654 struct propagate_block_info *pbi;
2658 /* If this is a store to a predicate register, the value of the
2659 predicate is changing, we don't know that the predicate as seen
2660 before is the same as that seen after. Flush all dependent
2661 conditions from reg_cond_dead. This will make all such
2662 conditionally live registers unconditionally live. */
2663 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
2664 flush_reg_cond_reg (pbi, regno);
2666 /* If this is an unconditional store, remove any conditional
2667 life that may have existed. */
2668 if (cond == NULL_RTX)
2669 splay_tree_remove (pbi->reg_cond_dead, regno);
2672 splay_tree_node node;
2673 struct reg_cond_life_info *rcli;
2676 /* Otherwise this is a conditional set. Record that fact.
2677 It may have been conditionally used, or there may be a
2678 subsequent set with a complimentary condition. */
2680 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
2683 /* The register was unconditionally live previously.
2684 Record the current condition as the condition under
2685 which it is dead. */
2686 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
2687 rcli->condition = cond;
2688 rcli->stores = cond;
2689 rcli->orig_condition = const0_rtx;
2690 splay_tree_insert (pbi->reg_cond_dead, regno,
2691 (splay_tree_value) rcli);
2693 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2695 /* Not unconditionaly dead. */
2700 /* The register was conditionally live previously.
2701 Add the new condition to the old. */
2702 rcli = (struct reg_cond_life_info *) node->value;
2703 ncond = rcli->condition;
2704 ncond = ior_reg_cond (ncond, cond, 1);
2705 if (rcli->stores == const0_rtx)
2706 rcli->stores = cond;
2707 else if (rcli->stores != const1_rtx)
2708 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
2710 /* If the register is now unconditionally dead, remove the entry
2711 in the splay_tree. A register is unconditionally dead if the
2712 dead condition ncond is true. A register is also unconditionally
2713 dead if the sum of all conditional stores is an unconditional
2714 store (stores is true), and the dead condition is identically the
2715 same as the original dead condition initialized at the end of
2716 the block. This is a pointer compare, not an rtx_equal_p
2718 if (ncond == const1_rtx
2719 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
2720 splay_tree_remove (pbi->reg_cond_dead, regno);
2723 rcli->condition = ncond;
2725 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2727 /* Not unconditionaly dead. */
2736 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2739 free_reg_cond_life_info (value)
2740 splay_tree_value value;
2742 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
2746 /* Helper function for flush_reg_cond_reg. */
2749 flush_reg_cond_reg_1 (node, data)
2750 splay_tree_node node;
2753 struct reg_cond_life_info *rcli;
2754 int *xdata = (int *) data;
2755 unsigned int regno = xdata[0];
2757 /* Don't need to search if last flushed value was farther on in
2758 the in-order traversal. */
2759 if (xdata[1] >= (int) node->key)
2762 /* Splice out portions of the expression that refer to regno. */
2763 rcli = (struct reg_cond_life_info *) node->value;
2764 rcli->condition = elim_reg_cond (rcli->condition, regno);
2765 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
2766 rcli->stores = elim_reg_cond (rcli->stores, regno);
2768 /* If the entire condition is now false, signal the node to be removed. */
2769 if (rcli->condition == const0_rtx)
2771 xdata[1] = node->key;
2774 else if (rcli->condition == const1_rtx)
2780 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2783 flush_reg_cond_reg (pbi, regno)
2784 struct propagate_block_info *pbi;
2791 while (splay_tree_foreach (pbi->reg_cond_dead,
2792 flush_reg_cond_reg_1, pair) == -1)
2793 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
2795 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
2798 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2799 For ior/and, the ADD flag determines whether we want to add the new
2800 condition X to the old one unconditionally. If it is zero, we will
2801 only return a new expression if X allows us to simplify part of
2802 OLD, otherwise we return OLD unchanged to the caller.
2803 If ADD is nonzero, we will return a new condition in all cases. The
2804 toplevel caller of one of these functions should always pass 1 for
2808 ior_reg_cond (old, x, add)
2814 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
2816 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
2817 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
2818 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2820 if (GET_CODE (x) == GET_CODE (old)
2821 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2825 return gen_rtx_IOR (0, old, x);
2828 switch (GET_CODE (old))
2831 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
2832 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
2833 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
2835 if (op0 == const0_rtx)
2837 if (op1 == const0_rtx)
2839 if (op0 == const1_rtx || op1 == const1_rtx)
2841 if (op0 == XEXP (old, 0))
2842 op0 = gen_rtx_IOR (0, op0, x);
2844 op1 = gen_rtx_IOR (0, op1, x);
2845 return gen_rtx_IOR (0, op0, op1);
2849 return gen_rtx_IOR (0, old, x);
2852 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
2853 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
2854 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
2856 if (op0 == const1_rtx)
2858 if (op1 == const1_rtx)
2860 if (op0 == const0_rtx || op1 == const0_rtx)
2862 if (op0 == XEXP (old, 0))
2863 op0 = gen_rtx_IOR (0, op0, x);
2865 op1 = gen_rtx_IOR (0, op1, x);
2866 return gen_rtx_AND (0, op0, op1);
2870 return gen_rtx_IOR (0, old, x);
2873 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
2874 if (op0 != XEXP (old, 0))
2875 return not_reg_cond (op0);
2878 return gen_rtx_IOR (0, old, x);
2889 enum rtx_code x_code;
2891 if (x == const0_rtx)
2893 else if (x == const1_rtx)
2895 x_code = GET_CODE (x);
2898 if (GET_RTX_CLASS (x_code) == '<'
2899 && GET_CODE (XEXP (x, 0)) == REG)
2901 if (XEXP (x, 1) != const0_rtx)
2904 return gen_rtx_fmt_ee (reverse_condition (x_code),
2905 VOIDmode, XEXP (x, 0), const0_rtx);
2907 return gen_rtx_NOT (0, x);
2911 and_reg_cond (old, x, add)
2917 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
2919 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
2920 && GET_CODE (x) == reverse_condition (GET_CODE (old))
2921 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2923 if (GET_CODE (x) == GET_CODE (old)
2924 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2928 return gen_rtx_AND (0, old, x);
2931 switch (GET_CODE (old))
2934 op0 = and_reg_cond (XEXP (old, 0), x, 0);
2935 op1 = and_reg_cond (XEXP (old, 1), x, 0);
2936 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
2938 if (op0 == const0_rtx)
2940 if (op1 == const0_rtx)
2942 if (op0 == const1_rtx || op1 == const1_rtx)
2944 if (op0 == XEXP (old, 0))
2945 op0 = gen_rtx_AND (0, op0, x);
2947 op1 = gen_rtx_AND (0, op1, x);
2948 return gen_rtx_IOR (0, op0, op1);
2952 return gen_rtx_AND (0, old, x);
2955 op0 = and_reg_cond (XEXP (old, 0), x, 0);
2956 op1 = and_reg_cond (XEXP (old, 1), x, 0);
2957 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
2959 if (op0 == const1_rtx)
2961 if (op1 == const1_rtx)
2963 if (op0 == const0_rtx || op1 == const0_rtx)
2965 if (op0 == XEXP (old, 0))
2966 op0 = gen_rtx_AND (0, op0, x);
2968 op1 = gen_rtx_AND (0, op1, x);
2969 return gen_rtx_AND (0, op0, op1);
2974 /* If X is identical to one of the existing terms of the AND,
2975 then just return what we already have. */
2976 /* ??? There really should be some sort of recursive check here in
2977 case there are nested ANDs. */
2978 if ((GET_CODE (XEXP (old, 0)) == GET_CODE (x)
2979 && REGNO (XEXP (XEXP (old, 0), 0)) == REGNO (XEXP (x, 0)))
2980 || (GET_CODE (XEXP (old, 1)) == GET_CODE (x)
2981 && REGNO (XEXP (XEXP (old, 1), 0)) == REGNO (XEXP (x, 0))))
2984 return gen_rtx_AND (0, old, x);
2987 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
2988 if (op0 != XEXP (old, 0))
2989 return not_reg_cond (op0);
2992 return gen_rtx_AND (0, old, x);
2999 /* Given a condition X, remove references to reg REGNO and return the
3000 new condition. The removal will be done so that all conditions
3001 involving REGNO are considered to evaluate to false. This function
3002 is used when the value of REGNO changes. */
3005 elim_reg_cond (x, regno)
3011 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
3013 if (REGNO (XEXP (x, 0)) == regno)
3018 switch (GET_CODE (x))
3021 op0 = elim_reg_cond (XEXP (x, 0), regno);
3022 op1 = elim_reg_cond (XEXP (x, 1), regno);
3023 if (op0 == const0_rtx || op1 == const0_rtx)
3025 if (op0 == const1_rtx)
3027 if (op1 == const1_rtx)
3029 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3031 return gen_rtx_AND (0, op0, op1);
3034 op0 = elim_reg_cond (XEXP (x, 0), regno);
3035 op1 = elim_reg_cond (XEXP (x, 1), regno);
3036 if (op0 == const1_rtx || op1 == const1_rtx)
3038 if (op0 == const0_rtx)
3040 if (op1 == const0_rtx)
3042 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3044 return gen_rtx_IOR (0, op0, op1);
3047 op0 = elim_reg_cond (XEXP (x, 0), regno);
3048 if (op0 == const0_rtx)
3050 if (op0 == const1_rtx)
3052 if (op0 != XEXP (x, 0))
3053 return not_reg_cond (op0);
3060 #endif /* HAVE_conditional_execution */
3064 /* Try to substitute the auto-inc expression INC as the address inside
3065 MEM which occurs in INSN. Currently, the address of MEM is an expression
3066 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3067 that has a single set whose source is a PLUS of INCR_REG and something
3071 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
3072 struct propagate_block_info *pbi;
3073 rtx inc, insn, mem, incr, incr_reg;
3075 int regno = REGNO (incr_reg);
3076 rtx set = single_set (incr);
3077 rtx q = SET_DEST (set);
3078 rtx y = SET_SRC (set);
3079 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
3081 /* Make sure this reg appears only once in this insn. */
3082 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
3085 if (dead_or_set_p (incr, incr_reg)
3086 /* Mustn't autoinc an eliminable register. */
3087 && (regno >= FIRST_PSEUDO_REGISTER
3088 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
3090 /* This is the simple case. Try to make the auto-inc. If
3091 we can't, we are done. Otherwise, we will do any
3092 needed updates below. */
3093 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
3096 else if (GET_CODE (q) == REG
3097 /* PREV_INSN used here to check the semi-open interval
3099 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
3100 /* We must also check for sets of q as q may be
3101 a call clobbered hard register and there may
3102 be a call between PREV_INSN (insn) and incr. */
3103 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
3105 /* We have *p followed sometime later by q = p+size.
3106 Both p and q must be live afterward,
3107 and q is not used between INSN and its assignment.
3108 Change it to q = p, ...*q..., q = q+size.
3109 Then fall into the usual case. */
3113 emit_move_insn (q, incr_reg);
3114 insns = get_insns ();
3117 /* If we can't make the auto-inc, or can't make the
3118 replacement into Y, exit. There's no point in making
3119 the change below if we can't do the auto-inc and doing
3120 so is not correct in the pre-inc case. */
3123 validate_change (insn, &XEXP (mem, 0), inc, 1);
3124 validate_change (incr, &XEXP (y, opnum), q, 1);
3125 if (! apply_change_group ())
3128 /* We now know we'll be doing this change, so emit the
3129 new insn(s) and do the updates. */
3130 emit_insns_before (insns, insn);
3132 if (pbi->bb->head == insn)
3133 pbi->bb->head = insns;
3135 /* INCR will become a NOTE and INSN won't contain a
3136 use of INCR_REG. If a use of INCR_REG was just placed in
3137 the insn before INSN, make that the next use.
3138 Otherwise, invalidate it. */
3139 if (GET_CODE (PREV_INSN (insn)) == INSN
3140 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
3141 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
3142 pbi->reg_next_use[regno] = PREV_INSN (insn);
3144 pbi->reg_next_use[regno] = 0;
3149 /* REGNO is now used in INCR which is below INSN, but
3150 it previously wasn't live here. If we don't mark
3151 it as live, we'll put a REG_DEAD note for it
3152 on this insn, which is incorrect. */
3153 SET_REGNO_REG_SET (pbi->reg_live, regno);
3155 /* If there are any calls between INSN and INCR, show
3156 that REGNO now crosses them. */
3157 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
3158 if (GET_CODE (temp) == CALL_INSN)
3159 REG_N_CALLS_CROSSED (regno)++;
3161 /* Invalidate alias info for Q since we just changed its value. */
3162 clear_reg_alias_info (q);
3167 /* If we haven't returned, it means we were able to make the
3168 auto-inc, so update the status. First, record that this insn
3169 has an implicit side effect. */
3171 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
3173 /* Modify the old increment-insn to simply copy
3174 the already-incremented value of our register. */
3175 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
3178 /* If that makes it a no-op (copying the register into itself) delete
3179 it so it won't appear to be a "use" and a "set" of this
3181 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
3183 /* If the original source was dead, it's dead now. */
3186 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
3188 remove_note (incr, note);
3189 if (XEXP (note, 0) != incr_reg)
3190 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
3193 PUT_CODE (incr, NOTE);
3194 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
3195 NOTE_SOURCE_FILE (incr) = 0;
3198 if (regno >= FIRST_PSEUDO_REGISTER)
3200 /* Count an extra reference to the reg. When a reg is
3201 incremented, spilling it is worse, so we want to make
3202 that less likely. */
3203 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3205 /* Count the increment as a setting of the register,
3206 even though it isn't a SET in rtl. */
3207 REG_N_SETS (regno)++;
3211 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3215 find_auto_inc (pbi, x, insn)
3216 struct propagate_block_info *pbi;
3220 rtx addr = XEXP (x, 0);
3221 HOST_WIDE_INT offset = 0;
3222 rtx set, y, incr, inc_val;
3224 int size = GET_MODE_SIZE (GET_MODE (x));
3226 if (GET_CODE (insn) == JUMP_INSN)
3229 /* Here we detect use of an index register which might be good for
3230 postincrement, postdecrement, preincrement, or predecrement. */
3232 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
3233 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
3235 if (GET_CODE (addr) != REG)
3238 regno = REGNO (addr);
3240 /* Is the next use an increment that might make auto-increment? */
3241 incr = pbi->reg_next_use[regno];
3242 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
3244 set = single_set (incr);
3245 if (set == 0 || GET_CODE (set) != SET)
3249 if (GET_CODE (y) != PLUS)
3252 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
3253 inc_val = XEXP (y, 1);
3254 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
3255 inc_val = XEXP (y, 0);
3259 if (GET_CODE (inc_val) == CONST_INT)
3261 if (HAVE_POST_INCREMENT
3262 && (INTVAL (inc_val) == size && offset == 0))
3263 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
3265 else if (HAVE_POST_DECREMENT
3266 && (INTVAL (inc_val) == -size && offset == 0))
3267 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
3269 else if (HAVE_PRE_INCREMENT
3270 && (INTVAL (inc_val) == size && offset == size))
3271 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
3273 else if (HAVE_PRE_DECREMENT
3274 && (INTVAL (inc_val) == -size && offset == -size))
3275 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
3277 else if (HAVE_POST_MODIFY_DISP && offset == 0)
3278 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3279 gen_rtx_PLUS (Pmode,
3282 insn, x, incr, addr);
3284 else if (GET_CODE (inc_val) == REG
3285 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
3289 if (HAVE_POST_MODIFY_REG && offset == 0)
3290 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3291 gen_rtx_PLUS (Pmode,
3294 insn, x, incr, addr);
3298 #endif /* AUTO_INC_DEC */
3301 mark_used_reg (pbi, reg, cond, insn)
3302 struct propagate_block_info *pbi;
3304 rtx cond ATTRIBUTE_UNUSED;
3307 unsigned int regno_first, regno_last, i;
3308 int some_was_live, some_was_dead, some_not_set;
3310 regno_last = regno_first = REGNO (reg);
3311 if (regno_first < FIRST_PSEUDO_REGISTER)
3312 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
3314 /* Find out if any of this register is live after this instruction. */
3315 some_was_live = some_was_dead = 0;
3316 for (i = regno_first; i <= regno_last; ++i)
3318 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
3319 some_was_live |= needed_regno;
3320 some_was_dead |= ! needed_regno;
3323 /* Find out if any of the register was set this insn. */
3325 for (i = regno_first; i <= regno_last; ++i)
3326 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
3328 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3330 /* Record where each reg is used, so when the reg is set we know
3331 the next insn that uses it. */
3332 pbi->reg_next_use[regno_first] = insn;
3335 if (pbi->flags & PROP_REG_INFO)
3337 if (regno_first < FIRST_PSEUDO_REGISTER)
3339 /* If this is a register we are going to try to eliminate,
3340 don't mark it live here. If we are successful in
3341 eliminating it, it need not be live unless it is used for
3342 pseudos, in which case it will have been set live when it
3343 was allocated to the pseudos. If the register will not
3344 be eliminated, reload will set it live at that point.
3346 Otherwise, record that this function uses this register. */
3347 /* ??? The PPC backend tries to "eliminate" on the pic
3348 register to itself. This should be fixed. In the mean
3349 time, hack around it. */
3351 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
3352 && (regno_first == FRAME_POINTER_REGNUM
3353 || regno_first == ARG_POINTER_REGNUM)))
3354 for (i = regno_first; i <= regno_last; ++i)
3355 regs_ever_live[i] = 1;
3359 /* Keep track of which basic block each reg appears in. */
3361 int blocknum = pbi->bb->index;
3362 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
3363 REG_BASIC_BLOCK (regno_first) = blocknum;
3364 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
3365 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
3367 /* Count (weighted) number of uses of each reg. */
3368 REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb);
3369 REG_N_REFS (regno_first)++;
3373 /* Record and count the insns in which a reg dies. If it is used in
3374 this insn and was dead below the insn then it dies in this insn.
3375 If it was set in this insn, we do not make a REG_DEAD note;
3376 likewise if we already made such a note. */
3377 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
3381 /* Check for the case where the register dying partially
3382 overlaps the register set by this insn. */
3383 if (regno_first != regno_last)
3384 for (i = regno_first; i <= regno_last; ++i)
3385 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
3387 /* If none of the words in X is needed, make a REG_DEAD note.
3388 Otherwise, we must make partial REG_DEAD notes. */
3389 if (! some_was_live)
3391 if ((pbi->flags & PROP_DEATH_NOTES)
3392 && ! find_regno_note (insn, REG_DEAD, regno_first))
3394 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
3396 if (pbi->flags & PROP_REG_INFO)
3397 REG_N_DEATHS (regno_first)++;
3401 /* Don't make a REG_DEAD note for a part of a register
3402 that is set in the insn. */
3403 for (i = regno_first; i <= regno_last; ++i)
3404 if (! REGNO_REG_SET_P (pbi->reg_live, i)
3405 && ! dead_or_set_regno_p (insn, i))
3407 = alloc_EXPR_LIST (REG_DEAD,
3408 gen_rtx_REG (reg_raw_mode[i], i),
3413 /* Mark the register as being live. */
3414 for (i = regno_first; i <= regno_last; ++i)
3416 SET_REGNO_REG_SET (pbi->reg_live, i);
3418 #ifdef HAVE_conditional_execution
3419 /* If this is a conditional use, record that fact. If it is later
3420 conditionally set, we'll know to kill the register. */
3421 if (cond != NULL_RTX)
3423 splay_tree_node node;
3424 struct reg_cond_life_info *rcli;
3429 node = splay_tree_lookup (pbi->reg_cond_dead, i);
3432 /* The register was unconditionally live previously.
3433 No need to do anything. */
3437 /* The register was conditionally live previously.
3438 Subtract the new life cond from the old death cond. */
3439 rcli = (struct reg_cond_life_info *) node->value;
3440 ncond = rcli->condition;
3441 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
3443 /* If the register is now unconditionally live,
3444 remove the entry in the splay_tree. */
3445 if (ncond == const0_rtx)
3446 splay_tree_remove (pbi->reg_cond_dead, i);
3449 rcli->condition = ncond;
3450 SET_REGNO_REG_SET (pbi->reg_cond_reg,
3451 REGNO (XEXP (cond, 0)));
3457 /* The register was not previously live at all. Record
3458 the condition under which it is still dead. */
3459 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
3460 rcli->condition = not_reg_cond (cond);
3461 rcli->stores = const0_rtx;
3462 rcli->orig_condition = const0_rtx;
3463 splay_tree_insert (pbi->reg_cond_dead, i,
3464 (splay_tree_value) rcli);
3466 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
3469 else if (some_was_live)
3471 /* The register may have been conditionally live previously, but
3472 is now unconditionally live. Remove it from the conditionally
3473 dead list, so that a conditional set won't cause us to think
3475 splay_tree_remove (pbi->reg_cond_dead, i);
3481 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3482 This is done assuming the registers needed from X are those that
3483 have 1-bits in PBI->REG_LIVE.
3485 INSN is the containing instruction. If INSN is dead, this function
3489 mark_used_regs (pbi, x, cond, insn)
3490 struct propagate_block_info *pbi;
3495 int flags = pbi->flags;
3498 code = GET_CODE (x);
3518 /* If we are clobbering a MEM, mark any registers inside the address
3520 if (GET_CODE (XEXP (x, 0)) == MEM)
3521 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
3525 /* Don't bother watching stores to mems if this is not the
3526 final pass. We'll not be deleting dead stores this round. */
3527 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
3529 /* Invalidate the data for the last MEM stored, but only if MEM is
3530 something that can be stored into. */
3531 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3532 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3533 /* Needn't clear the memory set list. */
3537 rtx temp = pbi->mem_set_list;
3538 rtx prev = NULL_RTX;
3543 next = XEXP (temp, 1);
3544 if (anti_dependence (XEXP (temp, 0), x))
3546 /* Splice temp out of the list. */
3548 XEXP (prev, 1) = next;
3550 pbi->mem_set_list = next;
3551 free_EXPR_LIST_node (temp);
3552 pbi->mem_set_list_len--;
3560 /* If the memory reference had embedded side effects (autoincrement
3561 address modes. Then we may need to kill some entries on the
3564 invalidate_mems_from_autoinc (pbi, insn);
3568 if (flags & PROP_AUTOINC)
3569 find_auto_inc (pbi, x, insn);
3574 #ifdef CLASS_CANNOT_CHANGE_MODE
3575 if (GET_CODE (SUBREG_REG (x)) == REG
3576 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
3577 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
3578 GET_MODE (SUBREG_REG (x))))
3579 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
3582 /* While we're here, optimize this case. */
3584 if (GET_CODE (x) != REG)
3589 /* See a register other than being set => mark it as needed. */
3590 mark_used_reg (pbi, x, cond, insn);
3595 rtx testreg = SET_DEST (x);
3598 /* If storing into MEM, don't show it as being used. But do
3599 show the address as being used. */
3600 if (GET_CODE (testreg) == MEM)
3603 if (flags & PROP_AUTOINC)
3604 find_auto_inc (pbi, testreg, insn);
3606 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
3607 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3611 /* Storing in STRICT_LOW_PART is like storing in a reg
3612 in that this SET might be dead, so ignore it in TESTREG.
3613 but in some other ways it is like using the reg.
3615 Storing in a SUBREG or a bit field is like storing the entire
3616 register in that if the register's value is not used
3617 then this SET is not needed. */
3618 while (GET_CODE (testreg) == STRICT_LOW_PART
3619 || GET_CODE (testreg) == ZERO_EXTRACT
3620 || GET_CODE (testreg) == SIGN_EXTRACT
3621 || GET_CODE (testreg) == SUBREG)
3623 #ifdef CLASS_CANNOT_CHANGE_MODE
3624 if (GET_CODE (testreg) == SUBREG
3625 && GET_CODE (SUBREG_REG (testreg)) == REG
3626 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
3627 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
3628 GET_MODE (testreg)))
3629 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
3632 /* Modifying a single register in an alternate mode
3633 does not use any of the old value. But these other
3634 ways of storing in a register do use the old value. */
3635 if (GET_CODE (testreg) == SUBREG
3636 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
3641 testreg = XEXP (testreg, 0);
3644 /* If this is a store into a register or group of registers,
3645 recursively scan the value being stored. */
3647 if ((GET_CODE (testreg) == PARALLEL
3648 && GET_MODE (testreg) == BLKmode)
3649 || (GET_CODE (testreg) == REG
3650 && (regno = REGNO (testreg),
3651 ! (regno == FRAME_POINTER_REGNUM
3652 && (! reload_completed || frame_pointer_needed)))
3653 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3654 && ! (regno == HARD_FRAME_POINTER_REGNUM
3655 && (! reload_completed || frame_pointer_needed))
3657 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3658 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
3663 mark_used_regs (pbi, SET_DEST (x), cond, insn);
3664 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3671 case UNSPEC_VOLATILE:
3675 /* Traditional and volatile asm instructions must be considered to use
3676 and clobber all hard registers, all pseudo-registers and all of
3677 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3679 Consider for instance a volatile asm that changes the fpu rounding
3680 mode. An insn should not be moved across this even if it only uses
3681 pseudo-regs because it might give an incorrectly rounded result.
3683 ?!? Unfortunately, marking all hard registers as live causes massive
3684 problems for the register allocator and marking all pseudos as live
3685 creates mountains of uninitialized variable warnings.
3687 So for now, just clear the memory set list and mark any regs
3688 we can find in ASM_OPERANDS as used. */
3689 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
3691 free_EXPR_LIST_list (&pbi->mem_set_list);
3692 pbi->mem_set_list_len = 0;
3695 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3696 We can not just fall through here since then we would be confused
3697 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3698 traditional asms unlike their normal usage. */
3699 if (code == ASM_OPERANDS)
3703 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
3704 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
3710 if (cond != NULL_RTX)
3713 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
3715 cond = COND_EXEC_TEST (x);
3716 x = COND_EXEC_CODE (x);
3720 /* We _do_not_ want to scan operands of phi nodes. Operands of
3721 a phi function are evaluated only when control reaches this
3722 block along a particular edge. Therefore, regs that appear
3723 as arguments to phi should not be added to the global live at
3731 /* Recursively scan the operands of this expression. */
3734 const char * const fmt = GET_RTX_FORMAT (code);
3737 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3741 /* Tail recursive case: save a function call level. */
3747 mark_used_regs (pbi, XEXP (x, i), cond, insn);
3749 else if (fmt[i] == 'E')
3752 for (j = 0; j < XVECLEN (x, i); j++)
3753 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
3762 try_pre_increment_1 (pbi, insn)
3763 struct propagate_block_info *pbi;
3766 /* Find the next use of this reg. If in same basic block,
3767 make it do pre-increment or pre-decrement if appropriate. */
3768 rtx x = single_set (insn);
3769 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
3770 * INTVAL (XEXP (SET_SRC (x), 1)));
3771 int regno = REGNO (SET_DEST (x));
3772 rtx y = pbi->reg_next_use[regno];
3774 && SET_DEST (x) != stack_pointer_rtx
3775 && BLOCK_NUM (y) == BLOCK_NUM (insn)
3776 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3777 mode would be better. */
3778 && ! dead_or_set_p (y, SET_DEST (x))
3779 && try_pre_increment (y, SET_DEST (x), amount))
3781 /* We have found a suitable auto-increment and already changed
3782 insn Y to do it. So flush this increment instruction. */
3783 propagate_block_delete_insn (pbi->bb, insn);
3785 /* Count a reference to this reg for the increment insn we are
3786 deleting. When a reg is incremented, spilling it is worse,
3787 so we want to make that less likely. */
3788 if (regno >= FIRST_PSEUDO_REGISTER)
3790 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3791 REG_N_SETS (regno)++;
3794 /* Flush any remembered memories depending on the value of
3795 the incremented register. */
3796 invalidate_mems_from_set (pbi, SET_DEST (x));
3803 /* Try to change INSN so that it does pre-increment or pre-decrement
3804 addressing on register REG in order to add AMOUNT to REG.
3805 AMOUNT is negative for pre-decrement.
3806 Returns 1 if the change could be made.
3807 This checks all about the validity of the result of modifying INSN. */
3810 try_pre_increment (insn, reg, amount)
3812 HOST_WIDE_INT amount;
3816 /* Nonzero if we can try to make a pre-increment or pre-decrement.
3817 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
3819 /* Nonzero if we can try to make a post-increment or post-decrement.
3820 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
3821 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
3822 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
3825 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
3828 /* From the sign of increment, see which possibilities are conceivable
3829 on this target machine. */
3830 if (HAVE_PRE_INCREMENT && amount > 0)
3832 if (HAVE_POST_INCREMENT && amount > 0)
3835 if (HAVE_PRE_DECREMENT && amount < 0)
3837 if (HAVE_POST_DECREMENT && amount < 0)
3840 if (! (pre_ok || post_ok))
3843 /* It is not safe to add a side effect to a jump insn
3844 because if the incremented register is spilled and must be reloaded
3845 there would be no way to store the incremented value back in memory. */
3847 if (GET_CODE (insn) == JUMP_INSN)
3852 use = find_use_as_address (PATTERN (insn), reg, 0);
3853 if (post_ok && (use == 0 || use == (rtx) 1))
3855 use = find_use_as_address (PATTERN (insn), reg, -amount);
3859 if (use == 0 || use == (rtx) 1)
3862 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
3865 /* See if this combination of instruction and addressing mode exists. */
3866 if (! validate_change (insn, &XEXP (use, 0),
3867 gen_rtx_fmt_e (amount > 0
3868 ? (do_post ? POST_INC : PRE_INC)
3869 : (do_post ? POST_DEC : PRE_DEC),
3873 /* Record that this insn now has an implicit side effect on X. */
3874 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
3878 #endif /* AUTO_INC_DEC */
3880 /* Find the place in the rtx X where REG is used as a memory address.
3881 Return the MEM rtx that so uses it.
3882 If PLUSCONST is nonzero, search instead for a memory address equivalent to
3883 (plus REG (const_int PLUSCONST)).
3885 If such an address does not appear, return 0.
3886 If REG appears more than once, or is used other than in such an address,
3890 find_use_as_address (x, reg, plusconst)
3893 HOST_WIDE_INT plusconst;
3895 enum rtx_code code = GET_CODE (x);
3896 const char * const fmt = GET_RTX_FORMAT (code);
3901 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
3904 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
3905 && XEXP (XEXP (x, 0), 0) == reg
3906 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
3907 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
3910 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
3912 /* If REG occurs inside a MEM used in a bit-field reference,
3913 that is unacceptable. */
3914 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
3915 return (rtx) (HOST_WIDE_INT) 1;
3919 return (rtx) (HOST_WIDE_INT) 1;
3921 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3925 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
3929 return (rtx) (HOST_WIDE_INT) 1;
3931 else if (fmt[i] == 'E')
3934 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
3936 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
3940 return (rtx) (HOST_WIDE_INT) 1;
3948 /* Write information about registers and basic blocks into FILE.
3949 This is part of making a debugging dump. */
3952 dump_regset (r, outf)
3959 fputs (" (nil)", outf);
3963 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
3965 fprintf (outf, " %d", i);
3966 if (i < FIRST_PSEUDO_REGISTER)
3967 fprintf (outf, " [%s]",
3972 /* Print a human-reaable representation of R on the standard error
3973 stream. This function is designed to be used from within the
3980 dump_regset (r, stderr);
3981 putc ('\n', stderr);
3984 /* Dump the rtl into the current debugging dump file, then abort. */
3987 print_rtl_and_abort_fcn (file, line, function)
3990 const char *function;
3994 print_rtl_with_bb (rtl_dump_file, get_insns ());
3995 fclose (rtl_dump_file);
3998 fancy_abort (file, line, function);
4001 /* Recompute register set/reference counts immediately prior to register
4004 This avoids problems with set/reference counts changing to/from values
4005 which have special meanings to the register allocators.
4007 Additionally, the reference counts are the primary component used by the
4008 register allocators to prioritize pseudos for allocation to hard regs.
4009 More accurate reference counts generally lead to better register allocation.
4011 F is the first insn to be scanned.
4013 LOOP_STEP denotes how much loop_depth should be incremented per
4014 loop nesting level in order to increase the ref count more for
4015 references in a loop.
4017 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4018 possibly other information which is used by the register allocators. */
4021 recompute_reg_usage (f, loop_step)
4022 rtx f ATTRIBUTE_UNUSED;
4023 int loop_step ATTRIBUTE_UNUSED;
4025 allocate_reg_life_data ();
4026 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
4029 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4030 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4031 of the number of registers that died. */
4034 count_or_remove_death_notes (blocks, kill)
4040 for (i = n_basic_blocks - 1; i >= 0; --i)
4045 if (blocks && ! TEST_BIT (blocks, i))
4048 bb = BASIC_BLOCK (i);
4050 for (insn = bb->head;; insn = NEXT_INSN (insn))
4054 rtx *pprev = ®_NOTES (insn);
4059 switch (REG_NOTE_KIND (link))
4062 if (GET_CODE (XEXP (link, 0)) == REG)
4064 rtx reg = XEXP (link, 0);
4067 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
4070 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
4078 rtx next = XEXP (link, 1);
4079 free_EXPR_LIST_node (link);
4080 *pprev = link = next;
4086 pprev = &XEXP (link, 1);
4093 if (insn == bb->end)
4100 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4101 if blocks is NULL. */
4104 clear_log_links (blocks)
4112 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4114 free_INSN_LIST_list (&LOG_LINKS (insn));
4117 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4119 basic_block bb = BASIC_BLOCK (i);
4121 for (insn = bb->head; insn != NEXT_INSN (bb->end);
4122 insn = NEXT_INSN (insn))
4124 free_INSN_LIST_list (&LOG_LINKS (insn));
4128 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4129 correspond to the hard registers, if any, set in that map. This
4130 could be done far more efficiently by having all sorts of special-cases
4131 with moving single words, but probably isn't worth the trouble. */
4134 reg_set_to_hard_reg_set (to, from)
4140 EXECUTE_IF_SET_IN_BITMAP
4143 if (i >= FIRST_PSEUDO_REGISTER)
4145 SET_HARD_REG_BIT (*to, i);