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 /* Forward declarations */
284 static int verify_wide_reg_1 PARAMS ((rtx *, void *));
285 static void verify_wide_reg PARAMS ((int, basic_block));
286 static void verify_local_live_at_start PARAMS ((regset, basic_block));
287 static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *));
288 static void notice_stack_pointer_modification PARAMS ((rtx));
289 static void mark_reg PARAMS ((rtx, void *));
290 static void mark_regs_live_at_end PARAMS ((regset));
291 static int set_phi_alternative_reg PARAMS ((rtx, int, int, void *));
292 static void calculate_global_regs_live PARAMS ((sbitmap, sbitmap, int));
293 static void propagate_block_delete_insn PARAMS ((basic_block, rtx));
294 static rtx propagate_block_delete_libcall PARAMS ((rtx, rtx));
295 static int insn_dead_p PARAMS ((struct propagate_block_info *,
297 static int libcall_dead_p PARAMS ((struct propagate_block_info *,
299 static void mark_set_regs PARAMS ((struct propagate_block_info *,
301 static void mark_set_1 PARAMS ((struct propagate_block_info *,
302 enum rtx_code, rtx, rtx,
304 static int find_regno_partial PARAMS ((rtx *, void *));
306 #ifdef HAVE_conditional_execution
307 static int mark_regno_cond_dead PARAMS ((struct propagate_block_info *,
309 static void free_reg_cond_life_info PARAMS ((splay_tree_value));
310 static int flush_reg_cond_reg_1 PARAMS ((splay_tree_node, void *));
311 static void flush_reg_cond_reg PARAMS ((struct propagate_block_info *,
313 static rtx elim_reg_cond PARAMS ((rtx, unsigned int));
314 static rtx ior_reg_cond PARAMS ((rtx, rtx, int));
315 static rtx not_reg_cond PARAMS ((rtx));
316 static rtx and_reg_cond PARAMS ((rtx, rtx, int));
319 static void attempt_auto_inc PARAMS ((struct propagate_block_info *,
320 rtx, rtx, rtx, rtx, rtx));
321 static void find_auto_inc PARAMS ((struct propagate_block_info *,
323 static int try_pre_increment_1 PARAMS ((struct propagate_block_info *,
325 static int try_pre_increment PARAMS ((rtx, rtx, HOST_WIDE_INT));
327 static void mark_used_reg PARAMS ((struct propagate_block_info *,
329 static void mark_used_regs PARAMS ((struct propagate_block_info *,
331 void dump_flow_info PARAMS ((FILE *));
332 void debug_flow_info PARAMS ((void));
333 static void add_to_mem_set_list PARAMS ((struct propagate_block_info *,
335 static void invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *,
337 static void invalidate_mems_from_set PARAMS ((struct propagate_block_info *,
339 static void clear_log_links PARAMS ((sbitmap));
343 check_function_return_warnings ()
345 if (warn_missing_noreturn
346 && !TREE_THIS_VOLATILE (cfun->decl)
347 && EXIT_BLOCK_PTR->pred == NULL
348 && (lang_missing_noreturn_ok_p
349 && !lang_missing_noreturn_ok_p (cfun->decl)))
350 warning ("function might be possible candidate for attribute `noreturn'");
352 /* If we have a path to EXIT, then we do return. */
353 if (TREE_THIS_VOLATILE (cfun->decl)
354 && EXIT_BLOCK_PTR->pred != NULL)
355 warning ("`noreturn' function does return");
357 /* If the clobber_return_insn appears in some basic block, then we
358 do reach the end without returning a value. */
359 else if (warn_return_type
360 && cfun->x_clobber_return_insn != NULL
361 && EXIT_BLOCK_PTR->pred != NULL)
363 int max_uid = get_max_uid ();
365 /* If clobber_return_insn was excised by jump1, then renumber_insns
366 can make max_uid smaller than the number still recorded in our rtx.
367 That's fine, since this is a quick way of verifying that the insn
368 is no longer in the chain. */
369 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
371 /* Recompute insn->block mapping, since the initial mapping is
372 set before we delete unreachable blocks. */
373 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL)
374 warning ("control reaches end of non-void function");
379 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
380 note associated with the BLOCK. */
383 first_insn_after_basic_block_note (block)
388 /* Get the first instruction in the block. */
391 if (insn == NULL_RTX)
393 if (GET_CODE (insn) == CODE_LABEL)
394 insn = NEXT_INSN (insn);
395 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
398 return NEXT_INSN (insn);
401 /* Perform data flow analysis.
402 F is the first insn of the function; FLAGS is a set of PROP_* flags
403 to be used in accumulating flow info. */
406 life_analysis (f, file, flags)
411 #ifdef ELIMINABLE_REGS
413 static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS;
416 /* Record which registers will be eliminated. We use this in
419 CLEAR_HARD_REG_SET (elim_reg_set);
421 #ifdef ELIMINABLE_REGS
422 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
423 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
425 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
429 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES);
431 /* The post-reload life analysis have (on a global basis) the same
432 registers live as was computed by reload itself. elimination
433 Otherwise offsets and such may be incorrect.
435 Reload will make some registers as live even though they do not
438 We don't want to create new auto-incs after reload, since they
439 are unlikely to be useful and can cause problems with shared
441 if (reload_completed)
442 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
444 /* We want alias analysis information for local dead store elimination. */
445 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
446 init_alias_analysis ();
448 /* Always remove no-op moves. Do this before other processing so
449 that we don't have to keep re-scanning them. */
450 delete_noop_moves (f);
451 purge_all_dead_edges (false);
453 /* Some targets can emit simpler epilogues if they know that sp was
454 not ever modified during the function. After reload, of course,
455 we've already emitted the epilogue so there's no sense searching. */
456 if (! reload_completed)
457 notice_stack_pointer_modification (f);
459 /* Allocate and zero out data structures that will record the
460 data from lifetime analysis. */
461 allocate_reg_life_data ();
462 allocate_bb_life_data ();
464 /* Find the set of registers live on function exit. */
465 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
467 /* "Update" life info from zero. It'd be nice to begin the
468 relaxation with just the exit and noreturn blocks, but that set
469 is not immediately handy. */
471 if (flags & PROP_REG_INFO)
472 memset (regs_ever_live, 0, sizeof (regs_ever_live));
473 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
476 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
477 end_alias_analysis ();
480 dump_flow_info (file);
482 free_basic_block_vars (1);
484 #ifdef ENABLE_CHECKING
488 /* Search for any REG_LABEL notes which reference deleted labels. */
489 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
491 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
493 if (inote && GET_CODE (inote) == NOTE_INSN_DELETED_LABEL)
498 /* Removing dead insns should've made jumptables really dead. */
499 delete_dead_jumptables ();
502 /* A subroutine of verify_wide_reg, called through for_each_rtx.
503 Search for REGNO. If found, return 2 if it is not wider than
507 verify_wide_reg_1 (px, pregno)
512 unsigned int regno = *(int *) pregno;
514 if (GET_CODE (x) == REG && REGNO (x) == regno)
516 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
523 /* A subroutine of verify_local_live_at_start. Search through insns
524 of BB looking for register REGNO. */
527 verify_wide_reg (regno, bb)
531 rtx head = bb->head, end = bb->end;
537 int r = for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no);
545 head = NEXT_INSN (head);
550 fprintf (rtl_dump_file, "Register %d died unexpectedly.\n", regno);
551 dump_bb (bb, rtl_dump_file);
556 /* A subroutine of update_life_info. Verify that there are no untoward
557 changes in live_at_start during a local update. */
560 verify_local_live_at_start (new_live_at_start, bb)
561 regset new_live_at_start;
564 if (reload_completed)
566 /* After reload, there are no pseudos, nor subregs of multi-word
567 registers. The regsets should exactly match. */
568 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
572 fprintf (rtl_dump_file,
573 "live_at_start mismatch in bb %d, aborting\nNew:\n",
575 debug_bitmap_file (rtl_dump_file, new_live_at_start);
576 fputs ("Old:\n", rtl_dump_file);
577 dump_bb (bb, rtl_dump_file);
586 /* Find the set of changed registers. */
587 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
589 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
591 /* No registers should die. */
592 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
596 fprintf (rtl_dump_file,
597 "Register %d died unexpectedly.\n", i);
598 dump_bb (bb, rtl_dump_file);
603 /* Verify that the now-live register is wider than word_mode. */
604 verify_wide_reg (i, bb);
609 /* Updates life information starting with the basic blocks set in BLOCKS.
610 If BLOCKS is null, consider it to be the universal set.
612 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
613 we are only expecting local modifications to basic blocks. If we find
614 extra registers live at the beginning of a block, then we either killed
615 useful data, or we have a broken split that wants data not provided.
616 If we find registers removed from live_at_start, that means we have
617 a broken peephole that is killing a register it shouldn't.
619 ??? This is not true in one situation -- when a pre-reload splitter
620 generates subregs of a multi-word pseudo, current life analysis will
621 lose the kill. So we _can_ have a pseudo go live. How irritating.
623 Including PROP_REG_INFO does not properly refresh regs_ever_live
624 unless the caller resets it to zero. */
627 update_life_info (blocks, extent, prop_flags)
629 enum update_life_extent extent;
633 regset_head tmp_head;
636 tmp = INITIALIZE_REG_SET (tmp_head);
638 timevar_push ((extent == UPDATE_LIFE_LOCAL || blocks)
639 ? TV_LIFE_UPDATE : TV_LIFE);
641 /* Changes to the CFG are only allowed when
642 doing a global update for the entire CFG. */
643 if ((prop_flags & PROP_ALLOW_CFG_CHANGES)
644 && (extent == UPDATE_LIFE_LOCAL || blocks))
647 /* For a global update, we go through the relaxation process again. */
648 if (extent != UPDATE_LIFE_LOCAL)
654 calculate_global_regs_live (blocks, blocks,
655 prop_flags & (PROP_SCAN_DEAD_CODE
656 | PROP_ALLOW_CFG_CHANGES));
658 if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
659 != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
662 /* Removing dead code may allow the CFG to be simplified which
663 in turn may allow for further dead code detection / removal. */
664 for (i = n_basic_blocks - 1; i >= 0; --i)
666 basic_block bb = BASIC_BLOCK (i);
668 COPY_REG_SET (tmp, bb->global_live_at_end);
669 changed |= propagate_block (bb, tmp, NULL, NULL,
670 prop_flags & (PROP_SCAN_DEAD_CODE
671 | PROP_KILL_DEAD_CODE));
674 if (! changed || ! cleanup_cfg (CLEANUP_EXPENSIVE))
678 /* If asked, remove notes from the blocks we'll update. */
679 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
680 count_or_remove_death_notes (blocks, 1);
683 /* Clear log links in case we are asked to (re)compute them. */
684 if (prop_flags & PROP_LOG_LINKS)
685 clear_log_links (blocks);
689 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
691 basic_block bb = BASIC_BLOCK (i);
693 COPY_REG_SET (tmp, bb->global_live_at_end);
694 propagate_block (bb, tmp, NULL, NULL, prop_flags);
696 if (extent == UPDATE_LIFE_LOCAL)
697 verify_local_live_at_start (tmp, bb);
702 for (i = n_basic_blocks - 1; i >= 0; --i)
704 basic_block bb = BASIC_BLOCK (i);
706 COPY_REG_SET (tmp, bb->global_live_at_end);
707 propagate_block (bb, tmp, NULL, NULL, prop_flags);
709 if (extent == UPDATE_LIFE_LOCAL)
710 verify_local_live_at_start (tmp, bb);
716 if (prop_flags & PROP_REG_INFO)
718 /* The only pseudos that are live at the beginning of the function
719 are those that were not set anywhere in the function. local-alloc
720 doesn't know how to handle these correctly, so mark them as not
721 local to any one basic block. */
722 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
723 FIRST_PSEUDO_REGISTER, i,
724 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
726 /* We have a problem with any pseudoreg that lives across the setjmp.
727 ANSI says that if a user variable does not change in value between
728 the setjmp and the longjmp, then the longjmp preserves it. This
729 includes longjmp from a place where the pseudo appears dead.
730 (In principle, the value still exists if it is in scope.)
731 If the pseudo goes in a hard reg, some other value may occupy
732 that hard reg where this pseudo is dead, thus clobbering the pseudo.
733 Conclusion: such a pseudo must not go in a hard reg. */
734 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
735 FIRST_PSEUDO_REGISTER, i,
737 if (regno_reg_rtx[i] != 0)
739 REG_LIVE_LENGTH (i) = -1;
740 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
744 timevar_pop ((extent == UPDATE_LIFE_LOCAL || blocks)
745 ? TV_LIFE_UPDATE : TV_LIFE);
748 /* Update life information in all blocks where BB_DIRTY is set. */
751 update_life_info_in_dirty_blocks (extent, prop_flags)
752 enum update_life_extent extent;
755 sbitmap update_life_blocks = sbitmap_alloc (n_basic_blocks);
759 sbitmap_zero (update_life_blocks);
760 for (block_num = 0; block_num < n_basic_blocks; block_num++)
761 if (BASIC_BLOCK (block_num)->flags & BB_DIRTY)
763 SET_BIT (update_life_blocks, block_num);
768 update_life_info (update_life_blocks, extent, prop_flags);
770 sbitmap_free (update_life_blocks);
773 /* Free the variables allocated by find_basic_blocks.
775 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
778 free_basic_block_vars (keep_head_end_p)
781 if (! keep_head_end_p)
783 if (basic_block_info)
786 VARRAY_FREE (basic_block_info);
790 ENTRY_BLOCK_PTR->aux = NULL;
791 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
792 EXIT_BLOCK_PTR->aux = NULL;
793 EXIT_BLOCK_PTR->global_live_at_start = NULL;
797 /* Delete any insns that copy a register to itself. */
800 delete_noop_moves (f)
801 rtx f ATTRIBUTE_UNUSED;
807 for (i = 0; i < n_basic_blocks; i++)
809 bb = BASIC_BLOCK (i);
810 for (insn = bb->head; insn != NEXT_INSN (bb->end); insn = next)
812 next = NEXT_INSN (insn);
813 if (INSN_P (insn) && noop_move_p (insn))
817 /* If we're about to remove the first insn of a libcall
818 then move the libcall note to the next real insn and
819 update the retval note. */
820 if ((note = find_reg_note (insn, REG_LIBCALL, NULL_RTX))
821 && XEXP (note, 0) != insn)
823 rtx new_libcall_insn = next_real_insn (insn);
824 rtx retval_note = find_reg_note (XEXP (note, 0),
825 REG_RETVAL, NULL_RTX);
826 REG_NOTES (new_libcall_insn)
827 = gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0),
828 REG_NOTES (new_libcall_insn));
829 XEXP (retval_note, 0) = new_libcall_insn;
832 /* Do not call delete_insn here since that may change
833 the basic block boundaries which upsets some callers. */
834 PUT_CODE (insn, NOTE);
835 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
836 NOTE_SOURCE_FILE (insn) = 0;
842 /* Delete any jump tables never referenced. We can't delete them at the
843 time of removing tablejump insn as they are referenced by the preceding
844 insns computing the destination, so we delay deleting and garbagecollect
845 them once life information is computed. */
847 delete_dead_jumptables ()
850 for (insn = get_insns (); insn; insn = next)
852 next = NEXT_INSN (insn);
853 if (GET_CODE (insn) == CODE_LABEL
854 && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
855 && GET_CODE (next) == JUMP_INSN
856 && (GET_CODE (PATTERN (next)) == ADDR_VEC
857 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
860 fprintf (rtl_dump_file, "Dead jumptable %i removed\n", INSN_UID (insn));
861 delete_insn (NEXT_INSN (insn));
863 next = NEXT_INSN (next);
868 /* Determine if the stack pointer is constant over the life of the function.
869 Only useful before prologues have been emitted. */
872 notice_stack_pointer_modification_1 (x, pat, data)
874 rtx pat ATTRIBUTE_UNUSED;
875 void *data ATTRIBUTE_UNUSED;
877 if (x == stack_pointer_rtx
878 /* The stack pointer is only modified indirectly as the result
879 of a push until later in flow. See the comments in rtl.texi
880 regarding Embedded Side-Effects on Addresses. */
881 || (GET_CODE (x) == MEM
882 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
883 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
884 current_function_sp_is_unchanging = 0;
888 notice_stack_pointer_modification (f)
893 /* Assume that the stack pointer is unchanging if alloca hasn't
895 current_function_sp_is_unchanging = !current_function_calls_alloca;
896 if (! current_function_sp_is_unchanging)
899 for (insn = f; insn; insn = NEXT_INSN (insn))
903 /* Check if insn modifies the stack pointer. */
904 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
906 if (! current_function_sp_is_unchanging)
912 /* Mark a register in SET. Hard registers in large modes get all
913 of their component registers set as well. */
920 regset set = (regset) xset;
921 int regno = REGNO (reg);
923 if (GET_MODE (reg) == BLKmode)
926 SET_REGNO_REG_SET (set, regno);
927 if (regno < FIRST_PSEUDO_REGISTER)
929 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
931 SET_REGNO_REG_SET (set, regno + n);
935 /* Mark those regs which are needed at the end of the function as live
936 at the end of the last basic block. */
939 mark_regs_live_at_end (set)
944 /* If exiting needs the right stack value, consider the stack pointer
945 live at the end of the function. */
946 if ((HAVE_epilogue && reload_completed)
947 || ! EXIT_IGNORE_STACK
948 || (! FRAME_POINTER_REQUIRED
949 && ! current_function_calls_alloca
950 && flag_omit_frame_pointer)
951 || current_function_sp_is_unchanging)
953 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
956 /* Mark the frame pointer if needed at the end of the function. If
957 we end up eliminating it, it will be removed from the live list
958 of each basic block by reload. */
960 if (! reload_completed || frame_pointer_needed)
962 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
963 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
964 /* If they are different, also mark the hard frame pointer as live. */
965 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
966 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
970 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
971 /* Many architectures have a GP register even without flag_pic.
972 Assume the pic register is not in use, or will be handled by
973 other means, if it is not fixed. */
974 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
975 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
976 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
979 /* Mark all global registers, and all registers used by the epilogue
980 as being live at the end of the function since they may be
981 referenced by our caller. */
982 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
983 if (global_regs[i] || EPILOGUE_USES (i))
984 SET_REGNO_REG_SET (set, i);
986 if (HAVE_epilogue && reload_completed)
988 /* Mark all call-saved registers that we actually used. */
989 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
990 if (regs_ever_live[i] && ! LOCAL_REGNO (i)
991 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
992 SET_REGNO_REG_SET (set, i);
995 #ifdef EH_RETURN_DATA_REGNO
996 /* Mark the registers that will contain data for the handler. */
997 if (reload_completed && current_function_calls_eh_return)
1000 unsigned regno = EH_RETURN_DATA_REGNO(i);
1001 if (regno == INVALID_REGNUM)
1003 SET_REGNO_REG_SET (set, regno);
1006 #ifdef EH_RETURN_STACKADJ_RTX
1007 if ((! HAVE_epilogue || ! reload_completed)
1008 && current_function_calls_eh_return)
1010 rtx tmp = EH_RETURN_STACKADJ_RTX;
1011 if (tmp && REG_P (tmp))
1012 mark_reg (tmp, set);
1015 #ifdef EH_RETURN_HANDLER_RTX
1016 if ((! HAVE_epilogue || ! reload_completed)
1017 && current_function_calls_eh_return)
1019 rtx tmp = EH_RETURN_HANDLER_RTX;
1020 if (tmp && REG_P (tmp))
1021 mark_reg (tmp, set);
1025 /* Mark function return value. */
1026 diddle_return_value (mark_reg, set);
1029 /* Callback function for for_each_successor_phi. DATA is a regset.
1030 Sets the SRC_REGNO, the regno of the phi alternative for phi node
1031 INSN, in the regset. */
1034 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
1035 rtx insn ATTRIBUTE_UNUSED;
1036 int dest_regno ATTRIBUTE_UNUSED;
1040 regset live = (regset) data;
1041 SET_REGNO_REG_SET (live, src_regno);
1045 /* Propagate global life info around the graph of basic blocks. Begin
1046 considering blocks with their corresponding bit set in BLOCKS_IN.
1047 If BLOCKS_IN is null, consider it the universal set.
1049 BLOCKS_OUT is set for every block that was changed. */
1052 calculate_global_regs_live (blocks_in, blocks_out, flags)
1053 sbitmap blocks_in, blocks_out;
1056 basic_block *queue, *qhead, *qtail, *qend;
1057 regset tmp, new_live_at_end, call_used;
1058 regset_head tmp_head, call_used_head;
1059 regset_head new_live_at_end_head;
1062 tmp = INITIALIZE_REG_SET (tmp_head);
1063 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
1064 call_used = INITIALIZE_REG_SET (call_used_head);
1066 /* Inconveniently, this is only readily available in hard reg set form. */
1067 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
1068 if (call_used_regs[i])
1069 SET_REGNO_REG_SET (call_used, i);
1071 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1072 because the `head == tail' style test for an empty queue doesn't
1073 work with a full queue. */
1074 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
1076 qhead = qend = queue + n_basic_blocks + 2;
1078 /* Queue the blocks set in the initial mask. Do this in reverse block
1079 number order so that we are more likely for the first round to do
1080 useful work. We use AUX non-null to flag that the block is queued. */
1083 /* Clear out the garbage that might be hanging out in bb->aux. */
1084 for (i = n_basic_blocks - 1; i >= 0; --i)
1085 BASIC_BLOCK (i)->aux = NULL;
1087 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
1089 basic_block bb = BASIC_BLOCK (i);
1096 for (i = 0; i < n_basic_blocks; ++i)
1098 basic_block bb = BASIC_BLOCK (i);
1105 sbitmap_zero (blocks_out);
1107 /* We work through the queue until there are no more blocks. What
1108 is live at the end of this block is precisely the union of what
1109 is live at the beginning of all its successors. So, we set its
1110 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1111 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1112 this block by walking through the instructions in this block in
1113 reverse order and updating as we go. If that changed
1114 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1115 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1117 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1118 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1119 must either be live at the end of the block, or used within the
1120 block. In the latter case, it will certainly never disappear
1121 from GLOBAL_LIVE_AT_START. In the former case, the register
1122 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1123 for one of the successor blocks. By induction, that cannot
1125 while (qhead != qtail)
1127 int rescan, changed;
1136 /* Begin by propagating live_at_start from the successor blocks. */
1137 CLEAR_REG_SET (new_live_at_end);
1138 for (e = bb->succ; e; e = e->succ_next)
1140 basic_block sb = e->dest;
1142 /* Call-clobbered registers die across exception and call edges. */
1143 /* ??? Abnormal call edges ignored for the moment, as this gets
1144 confused by sibling call edges, which crashes reg-stack. */
1145 if (e->flags & EDGE_EH)
1147 bitmap_operation (tmp, sb->global_live_at_start,
1148 call_used, BITMAP_AND_COMPL);
1149 IOR_REG_SET (new_live_at_end, tmp);
1152 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
1155 /* The all-important stack pointer must always be live. */
1156 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
1158 /* Before reload, there are a few registers that must be forced
1159 live everywhere -- which might not already be the case for
1160 blocks within infinite loops. */
1161 if (! reload_completed)
1163 /* Any reference to any pseudo before reload is a potential
1164 reference of the frame pointer. */
1165 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
1167 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1168 /* Pseudos with argument area equivalences may require
1169 reloading via the argument pointer. */
1170 if (fixed_regs[ARG_POINTER_REGNUM])
1171 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
1174 /* Any constant, or pseudo with constant equivalences, may
1175 require reloading from memory using the pic register. */
1176 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
1177 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
1178 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
1181 /* Regs used in phi nodes are not included in
1182 global_live_at_start, since they are live only along a
1183 particular edge. Set those regs that are live because of a
1184 phi node alternative corresponding to this particular block. */
1186 for_each_successor_phi (bb, &set_phi_alternative_reg,
1189 if (bb == ENTRY_BLOCK_PTR)
1191 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1195 /* On our first pass through this block, we'll go ahead and continue.
1196 Recognize first pass by local_set NULL. On subsequent passes, we
1197 get to skip out early if live_at_end wouldn't have changed. */
1199 if (bb->local_set == NULL)
1201 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1202 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1207 /* If any bits were removed from live_at_end, we'll have to
1208 rescan the block. This wouldn't be necessary if we had
1209 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1210 local_live is really dependent on live_at_end. */
1211 CLEAR_REG_SET (tmp);
1212 rescan = bitmap_operation (tmp, bb->global_live_at_end,
1213 new_live_at_end, BITMAP_AND_COMPL);
1217 /* If any of the registers in the new live_at_end set are
1218 conditionally set in this basic block, we must rescan.
1219 This is because conditional lifetimes at the end of the
1220 block do not just take the live_at_end set into account,
1221 but also the liveness at the start of each successor
1222 block. We can miss changes in those sets if we only
1223 compare the new live_at_end against the previous one. */
1224 CLEAR_REG_SET (tmp);
1225 rescan = bitmap_operation (tmp, new_live_at_end,
1226 bb->cond_local_set, BITMAP_AND);
1231 /* Find the set of changed bits. Take this opportunity
1232 to notice that this set is empty and early out. */
1233 CLEAR_REG_SET (tmp);
1234 changed = bitmap_operation (tmp, bb->global_live_at_end,
1235 new_live_at_end, BITMAP_XOR);
1239 /* If any of the changed bits overlap with local_set,
1240 we'll have to rescan the block. Detect overlap by
1241 the AND with ~local_set turning off bits. */
1242 rescan = bitmap_operation (tmp, tmp, bb->local_set,
1247 /* Let our caller know that BB changed enough to require its
1248 death notes updated. */
1250 SET_BIT (blocks_out, bb->index);
1254 /* Add to live_at_start the set of all registers in
1255 new_live_at_end that aren't in the old live_at_end. */
1257 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
1259 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1261 changed = bitmap_operation (bb->global_live_at_start,
1262 bb->global_live_at_start,
1269 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1271 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1272 into live_at_start. */
1273 propagate_block (bb, new_live_at_end, bb->local_set,
1274 bb->cond_local_set, flags);
1276 /* If live_at start didn't change, no need to go farther. */
1277 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
1280 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
1283 /* Queue all predecessors of BB so that we may re-examine
1284 their live_at_end. */
1285 for (e = bb->pred; e; e = e->pred_next)
1287 basic_block pb = e->src;
1288 if (pb->aux == NULL)
1299 FREE_REG_SET (new_live_at_end);
1300 FREE_REG_SET (call_used);
1304 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
1306 basic_block bb = BASIC_BLOCK (i);
1307 FREE_REG_SET (bb->local_set);
1308 FREE_REG_SET (bb->cond_local_set);
1313 for (i = n_basic_blocks - 1; i >= 0; --i)
1315 basic_block bb = BASIC_BLOCK (i);
1316 FREE_REG_SET (bb->local_set);
1317 FREE_REG_SET (bb->cond_local_set);
1325 /* This structure is used to pass parameters to an from the
1326 the function find_regno_partial(). It is used to pass in the
1327 register number we are looking, as well as to return any rtx
1331 unsigned regno_to_find;
1333 } find_regno_partial_param;
1336 /* Find the rtx for the reg numbers specified in 'data' if it is
1337 part of an expression which only uses part of the register. Return
1338 it in the structure passed in. */
1340 find_regno_partial (ptr, data)
1344 find_regno_partial_param *param = (find_regno_partial_param *)data;
1345 unsigned reg = param->regno_to_find;
1346 param->retval = NULL_RTX;
1348 if (*ptr == NULL_RTX)
1351 switch (GET_CODE (*ptr))
1355 case STRICT_LOW_PART:
1356 if (GET_CODE (XEXP (*ptr, 0)) == REG && REGNO (XEXP (*ptr, 0)) == reg)
1358 param->retval = XEXP (*ptr, 0);
1364 if (GET_CODE (SUBREG_REG (*ptr)) == REG
1365 && REGNO (SUBREG_REG (*ptr)) == reg)
1367 param->retval = SUBREG_REG (*ptr);
1379 /* Process all immediate successors of the entry block looking for pseudo
1380 registers which are live on entry. Find all of those whose first
1381 instance is a partial register reference of some kind, and initialize
1382 them to 0 after the entry block. This will prevent bit sets within
1383 registers whose value is unknown, and may contain some kind of sticky
1384 bits we don't want. */
1387 initialize_uninitialized_subregs ()
1391 int reg, did_something = 0;
1392 find_regno_partial_param param;
1394 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
1396 basic_block bb = e->dest;
1397 regset map = bb->global_live_at_start;
1398 EXECUTE_IF_SET_IN_REG_SET (map,
1399 FIRST_PSEUDO_REGISTER, reg,
1401 int uid = REGNO_FIRST_UID (reg);
1404 /* Find an insn which mentions the register we are looking for.
1405 Its preferable to have an instance of the register's rtl since
1406 there may be various flags set which we need to duplicate.
1407 If we can't find it, its probably an automatic whose initial
1408 value doesn't matter, or hopefully something we don't care about. */
1409 for (i = get_insns (); i && INSN_UID (i) != uid; i = NEXT_INSN (i))
1413 /* Found the insn, now get the REG rtx, if we can. */
1414 param.regno_to_find = reg;
1415 for_each_rtx (&i, find_regno_partial, ¶m);
1416 if (param.retval != NULL_RTX)
1418 insn = gen_move_insn (param.retval,
1419 CONST0_RTX (GET_MODE (param.retval)));
1420 insert_insn_on_edge (insn, e);
1428 commit_edge_insertions ();
1429 return did_something;
1433 /* Subroutines of life analysis. */
1435 /* Allocate the permanent data structures that represent the results
1436 of life analysis. Not static since used also for stupid life analysis. */
1439 allocate_bb_life_data ()
1443 for (i = 0; i < n_basic_blocks; i++)
1445 basic_block bb = BASIC_BLOCK (i);
1447 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1448 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1451 ENTRY_BLOCK_PTR->global_live_at_end
1452 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1453 EXIT_BLOCK_PTR->global_live_at_start
1454 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1456 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1460 allocate_reg_life_data ()
1464 max_regno = max_reg_num ();
1466 /* Recalculate the register space, in case it has grown. Old style
1467 vector oriented regsets would set regset_{size,bytes} here also. */
1468 allocate_reg_info (max_regno, FALSE, FALSE);
1470 /* Reset all the data we'll collect in propagate_block and its
1472 for (i = 0; i < max_regno; i++)
1476 REG_N_DEATHS (i) = 0;
1477 REG_N_CALLS_CROSSED (i) = 0;
1478 REG_LIVE_LENGTH (i) = 0;
1479 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
1483 /* Delete dead instructions for propagate_block. */
1486 propagate_block_delete_insn (bb, insn)
1490 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
1493 /* If the insn referred to a label, and that label was attached to
1494 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1495 pretty much mandatory to delete it, because the ADDR_VEC may be
1496 referencing labels that no longer exist.
1498 INSN may reference a deleted label, particularly when a jump
1499 table has been optimized into a direct jump. There's no
1500 real good way to fix up the reference to the deleted label
1501 when the label is deleted, so we just allow it here.
1503 After dead code elimination is complete, we do search for
1504 any REG_LABEL notes which reference deleted labels as a
1507 if (inote && GET_CODE (inote) == CODE_LABEL)
1509 rtx label = XEXP (inote, 0);
1512 /* The label may be forced if it has been put in the constant
1513 pool. If that is the only use we must discard the table
1514 jump following it, but not the label itself. */
1515 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
1516 && (next = next_nonnote_insn (label)) != NULL
1517 && GET_CODE (next) == JUMP_INSN
1518 && (GET_CODE (PATTERN (next)) == ADDR_VEC
1519 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
1521 rtx pat = PATTERN (next);
1522 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
1523 int len = XVECLEN (pat, diff_vec_p);
1526 for (i = 0; i < len; i++)
1527 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
1533 if (bb->end == insn)
1537 purge_dead_edges (bb);
1540 /* Delete dead libcalls for propagate_block. Return the insn
1541 before the libcall. */
1544 propagate_block_delete_libcall ( insn, note)
1547 rtx first = XEXP (note, 0);
1548 rtx before = PREV_INSN (first);
1550 delete_insn_chain (first, insn);
1554 /* Update the life-status of regs for one insn. Return the previous insn. */
1557 propagate_one_insn (pbi, insn)
1558 struct propagate_block_info *pbi;
1561 rtx prev = PREV_INSN (insn);
1562 int flags = pbi->flags;
1563 int insn_is_dead = 0;
1564 int libcall_is_dead = 0;
1568 if (! INSN_P (insn))
1571 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1572 if (flags & PROP_SCAN_DEAD_CODE)
1574 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
1575 libcall_is_dead = (insn_is_dead && note != 0
1576 && libcall_dead_p (pbi, note, insn));
1579 /* If an instruction consists of just dead store(s) on final pass,
1581 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
1583 /* If we're trying to delete a prologue or epilogue instruction
1584 that isn't flagged as possibly being dead, something is wrong.
1585 But if we are keeping the stack pointer depressed, we might well
1586 be deleting insns that are used to compute the amount to update
1587 it by, so they are fine. */
1588 if (reload_completed
1589 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1590 && (TYPE_RETURNS_STACK_DEPRESSED
1591 (TREE_TYPE (current_function_decl))))
1592 && (((HAVE_epilogue || HAVE_prologue)
1593 && prologue_epilogue_contains (insn))
1594 || (HAVE_sibcall_epilogue
1595 && sibcall_epilogue_contains (insn)))
1596 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
1597 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn);
1599 /* Record sets. Do this even for dead instructions, since they
1600 would have killed the values if they hadn't been deleted. */
1601 mark_set_regs (pbi, PATTERN (insn), insn);
1603 /* CC0 is now known to be dead. Either this insn used it,
1604 in which case it doesn't anymore, or clobbered it,
1605 so the next insn can't use it. */
1608 if (libcall_is_dead)
1609 prev = propagate_block_delete_libcall ( insn, note);
1611 propagate_block_delete_insn (pbi->bb, insn);
1616 /* See if this is an increment or decrement that can be merged into
1617 a following memory address. */
1620 rtx x = single_set (insn);
1622 /* Does this instruction increment or decrement a register? */
1623 if ((flags & PROP_AUTOINC)
1625 && GET_CODE (SET_DEST (x)) == REG
1626 && (GET_CODE (SET_SRC (x)) == PLUS
1627 || GET_CODE (SET_SRC (x)) == MINUS)
1628 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1629 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1630 /* Ok, look for a following memory ref we can combine with.
1631 If one is found, change the memory ref to a PRE_INC
1632 or PRE_DEC, cancel this insn, and return 1.
1633 Return 0 if nothing has been done. */
1634 && try_pre_increment_1 (pbi, insn))
1637 #endif /* AUTO_INC_DEC */
1639 CLEAR_REG_SET (pbi->new_set);
1641 /* If this is not the final pass, and this insn is copying the value of
1642 a library call and it's dead, don't scan the insns that perform the
1643 library call, so that the call's arguments are not marked live. */
1644 if (libcall_is_dead)
1646 /* Record the death of the dest reg. */
1647 mark_set_regs (pbi, PATTERN (insn), insn);
1649 insn = XEXP (note, 0);
1650 return PREV_INSN (insn);
1652 else if (GET_CODE (PATTERN (insn)) == SET
1653 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1654 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1655 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1656 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1657 /* We have an insn to pop a constant amount off the stack.
1658 (Such insns use PLUS regardless of the direction of the stack,
1659 and any insn to adjust the stack by a constant is always a pop.)
1660 These insns, if not dead stores, have no effect on life. */
1665 /* Any regs live at the time of a call instruction must not go
1666 in a register clobbered by calls. Find all regs now live and
1667 record this for them. */
1669 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
1670 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
1671 { REG_N_CALLS_CROSSED (i)++; });
1673 /* Record sets. Do this even for dead instructions, since they
1674 would have killed the values if they hadn't been deleted. */
1675 mark_set_regs (pbi, PATTERN (insn), insn);
1677 if (GET_CODE (insn) == CALL_INSN)
1683 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1684 cond = COND_EXEC_TEST (PATTERN (insn));
1686 /* Non-constant calls clobber memory. */
1687 if (! CONST_OR_PURE_CALL_P (insn))
1689 free_EXPR_LIST_list (&pbi->mem_set_list);
1690 pbi->mem_set_list_len = 0;
1693 /* There may be extra registers to be clobbered. */
1694 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1696 note = XEXP (note, 1))
1697 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
1698 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
1699 cond, insn, pbi->flags);
1701 /* Calls change all call-used and global registers. */
1702 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1703 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1705 /* We do not want REG_UNUSED notes for these registers. */
1706 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
1708 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
1712 /* If an insn doesn't use CC0, it becomes dead since we assume
1713 that every insn clobbers it. So show it dead here;
1714 mark_used_regs will set it live if it is referenced. */
1719 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
1720 if ((flags & PROP_EQUAL_NOTES)
1721 && ((note = find_reg_note (insn, REG_EQUAL, NULL_RTX))
1722 || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX))))
1723 mark_used_regs (pbi, XEXP (note, 0), NULL_RTX, insn);
1725 /* Sometimes we may have inserted something before INSN (such as a move)
1726 when we make an auto-inc. So ensure we will scan those insns. */
1728 prev = PREV_INSN (insn);
1731 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1737 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1738 cond = COND_EXEC_TEST (PATTERN (insn));
1740 /* Calls use their arguments. */
1741 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1743 note = XEXP (note, 1))
1744 if (GET_CODE (XEXP (note, 0)) == USE)
1745 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
1748 /* The stack ptr is used (honorarily) by a CALL insn. */
1749 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
1751 /* Calls may also reference any of the global registers,
1752 so they are made live. */
1753 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1755 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
1760 /* On final pass, update counts of how many insns in which each reg
1762 if (flags & PROP_REG_INFO)
1763 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
1764 { REG_LIVE_LENGTH (i)++; });
1769 /* Initialize a propagate_block_info struct for public consumption.
1770 Note that the structure itself is opaque to this file, but that
1771 the user can use the regsets provided here. */
1773 struct propagate_block_info *
1774 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
1776 regset live, local_set, cond_local_set;
1779 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
1782 pbi->reg_live = live;
1783 pbi->mem_set_list = NULL_RTX;
1784 pbi->mem_set_list_len = 0;
1785 pbi->local_set = local_set;
1786 pbi->cond_local_set = cond_local_set;
1790 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
1791 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
1793 pbi->reg_next_use = NULL;
1795 pbi->new_set = BITMAP_XMALLOC ();
1797 #ifdef HAVE_conditional_execution
1798 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
1799 free_reg_cond_life_info);
1800 pbi->reg_cond_reg = BITMAP_XMALLOC ();
1802 /* If this block ends in a conditional branch, for each register live
1803 from one side of the branch and not the other, record the register
1804 as conditionally dead. */
1805 if (GET_CODE (bb->end) == JUMP_INSN
1806 && any_condjump_p (bb->end))
1808 regset_head diff_head;
1809 regset diff = INITIALIZE_REG_SET (diff_head);
1810 basic_block bb_true, bb_false;
1811 rtx cond_true, cond_false, set_src;
1814 /* Identify the successor blocks. */
1815 bb_true = bb->succ->dest;
1816 if (bb->succ->succ_next != NULL)
1818 bb_false = bb->succ->succ_next->dest;
1820 if (bb->succ->flags & EDGE_FALLTHRU)
1822 basic_block t = bb_false;
1826 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
1831 /* This can happen with a conditional jump to the next insn. */
1832 if (JUMP_LABEL (bb->end) != bb_true->head)
1835 /* Simplest way to do nothing. */
1839 /* Extract the condition from the branch. */
1840 set_src = SET_SRC (pc_set (bb->end));
1841 cond_true = XEXP (set_src, 0);
1842 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
1843 GET_MODE (cond_true), XEXP (cond_true, 0),
1844 XEXP (cond_true, 1));
1845 if (GET_CODE (XEXP (set_src, 1)) == PC)
1848 cond_false = cond_true;
1852 /* Compute which register lead different lives in the successors. */
1853 if (bitmap_operation (diff, bb_true->global_live_at_start,
1854 bb_false->global_live_at_start, BITMAP_XOR))
1856 rtx reg = XEXP (cond_true, 0);
1858 if (GET_CODE (reg) == SUBREG)
1859 reg = SUBREG_REG (reg);
1861 if (GET_CODE (reg) != REG)
1864 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
1866 /* For each such register, mark it conditionally dead. */
1867 EXECUTE_IF_SET_IN_REG_SET
1870 struct reg_cond_life_info *rcli;
1873 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
1875 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
1879 rcli->condition = cond;
1880 rcli->stores = const0_rtx;
1881 rcli->orig_condition = cond;
1883 splay_tree_insert (pbi->reg_cond_dead, i,
1884 (splay_tree_value) rcli);
1888 FREE_REG_SET (diff);
1892 /* If this block has no successors, any stores to the frame that aren't
1893 used later in the block are dead. So make a pass over the block
1894 recording any such that are made and show them dead at the end. We do
1895 a very conservative and simple job here. */
1897 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1898 && (TYPE_RETURNS_STACK_DEPRESSED
1899 (TREE_TYPE (current_function_decl))))
1900 && (flags & PROP_SCAN_DEAD_CODE)
1901 && (bb->succ == NULL
1902 || (bb->succ->succ_next == NULL
1903 && bb->succ->dest == EXIT_BLOCK_PTR
1904 && ! current_function_calls_eh_return)))
1907 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
1908 if (GET_CODE (insn) == INSN
1909 && (set = single_set (insn))
1910 && GET_CODE (SET_DEST (set)) == MEM)
1912 rtx mem = SET_DEST (set);
1913 rtx canon_mem = canon_rtx (mem);
1915 /* This optimization is performed by faking a store to the
1916 memory at the end of the block. This doesn't work for
1917 unchanging memories because multiple stores to unchanging
1918 memory is illegal and alias analysis doesn't consider it. */
1919 if (RTX_UNCHANGING_P (canon_mem))
1922 if (XEXP (canon_mem, 0) == frame_pointer_rtx
1923 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
1924 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
1925 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
1926 add_to_mem_set_list (pbi, canon_mem);
1933 /* Release a propagate_block_info struct. */
1936 free_propagate_block_info (pbi)
1937 struct propagate_block_info *pbi;
1939 free_EXPR_LIST_list (&pbi->mem_set_list);
1941 BITMAP_XFREE (pbi->new_set);
1943 #ifdef HAVE_conditional_execution
1944 splay_tree_delete (pbi->reg_cond_dead);
1945 BITMAP_XFREE (pbi->reg_cond_reg);
1948 if (pbi->reg_next_use)
1949 free (pbi->reg_next_use);
1954 /* Compute the registers live at the beginning of a basic block BB from
1955 those live at the end.
1957 When called, REG_LIVE contains those live at the end. On return, it
1958 contains those live at the beginning.
1960 LOCAL_SET, if non-null, will be set with all registers killed
1961 unconditionally by this basic block.
1962 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
1963 killed conditionally by this basic block. If there is any unconditional
1964 set of a register, then the corresponding bit will be set in LOCAL_SET
1965 and cleared in COND_LOCAL_SET.
1966 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
1967 case, the resulting set will be equal to the union of the two sets that
1968 would otherwise be computed.
1970 Return non-zero if an INSN is deleted (i.e. by dead code removal). */
1973 propagate_block (bb, live, local_set, cond_local_set, flags)
1977 regset cond_local_set;
1980 struct propagate_block_info *pbi;
1984 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
1986 if (flags & PROP_REG_INFO)
1990 /* Process the regs live at the end of the block.
1991 Mark them as not local to any one basic block. */
1992 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
1993 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
1996 /* Scan the block an insn at a time from end to beginning. */
1999 for (insn = bb->end;; insn = prev)
2001 /* If this is a call to `setjmp' et al, warn if any
2002 non-volatile datum is live. */
2003 if ((flags & PROP_REG_INFO)
2004 && GET_CODE (insn) == CALL_INSN
2005 && find_reg_note (insn, REG_SETJMP, NULL))
2006 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
2008 prev = propagate_one_insn (pbi, insn);
2009 changed |= NEXT_INSN (prev) != insn;
2011 if (insn == bb->head)
2015 free_propagate_block_info (pbi);
2020 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2021 (SET expressions whose destinations are registers dead after the insn).
2022 NEEDED is the regset that says which regs are alive after the insn.
2024 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
2026 If X is the entire body of an insn, NOTES contains the reg notes
2027 pertaining to the insn. */
2030 insn_dead_p (pbi, x, call_ok, notes)
2031 struct propagate_block_info *pbi;
2034 rtx notes ATTRIBUTE_UNUSED;
2036 enum rtx_code code = GET_CODE (x);
2039 /* As flow is invoked after combine, we must take existing AUTO_INC
2040 expressions into account. */
2041 for (; notes; notes = XEXP (notes, 1))
2043 if (REG_NOTE_KIND (notes) == REG_INC)
2045 int regno = REGNO (XEXP (notes, 0));
2047 /* Don't delete insns to set global regs. */
2048 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2049 || REGNO_REG_SET_P (pbi->reg_live, regno))
2055 /* If setting something that's a reg or part of one,
2056 see if that register's altered value will be live. */
2060 rtx r = SET_DEST (x);
2063 if (GET_CODE (r) == CC0)
2064 return ! pbi->cc0_live;
2067 /* A SET that is a subroutine call cannot be dead. */
2068 if (GET_CODE (SET_SRC (x)) == CALL)
2074 /* Don't eliminate loads from volatile memory or volatile asms. */
2075 else if (volatile_refs_p (SET_SRC (x)))
2078 if (GET_CODE (r) == MEM)
2082 if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode)
2085 canon_r = canon_rtx (r);
2087 /* Walk the set of memory locations we are currently tracking
2088 and see if one is an identical match to this memory location.
2089 If so, this memory write is dead (remember, we're walking
2090 backwards from the end of the block to the start). Since
2091 rtx_equal_p does not check the alias set or flags, we also
2092 must have the potential for them to conflict (anti_dependence). */
2093 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
2094 if (anti_dependence (r, XEXP (temp, 0)))
2096 rtx mem = XEXP (temp, 0);
2098 if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0))
2099 && (GET_MODE_SIZE (GET_MODE (canon_r))
2100 <= GET_MODE_SIZE (GET_MODE (mem))))
2104 /* Check if memory reference matches an auto increment. Only
2105 post increment/decrement or modify are valid. */
2106 if (GET_MODE (mem) == GET_MODE (r)
2107 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
2108 || GET_CODE (XEXP (mem, 0)) == POST_INC
2109 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
2110 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
2111 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
2118 while (GET_CODE (r) == SUBREG
2119 || GET_CODE (r) == STRICT_LOW_PART
2120 || GET_CODE (r) == ZERO_EXTRACT)
2123 if (GET_CODE (r) == REG)
2125 int regno = REGNO (r);
2128 if (REGNO_REG_SET_P (pbi->reg_live, regno))
2131 /* If this is a hard register, verify that subsequent
2132 words are not needed. */
2133 if (regno < FIRST_PSEUDO_REGISTER)
2135 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
2138 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
2142 /* Don't delete insns to set global regs. */
2143 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2146 /* Make sure insns to set the stack pointer aren't deleted. */
2147 if (regno == STACK_POINTER_REGNUM)
2150 /* ??? These bits might be redundant with the force live bits
2151 in calculate_global_regs_live. We would delete from
2152 sequential sets; whether this actually affects real code
2153 for anything but the stack pointer I don't know. */
2154 /* Make sure insns to set the frame pointer aren't deleted. */
2155 if (regno == FRAME_POINTER_REGNUM
2156 && (! reload_completed || frame_pointer_needed))
2158 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2159 if (regno == HARD_FRAME_POINTER_REGNUM
2160 && (! reload_completed || frame_pointer_needed))
2164 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2165 /* Make sure insns to set arg pointer are never deleted
2166 (if the arg pointer isn't fixed, there will be a USE
2167 for it, so we can treat it normally). */
2168 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2172 /* Otherwise, the set is dead. */
2178 /* If performing several activities, insn is dead if each activity
2179 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2180 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2182 else if (code == PARALLEL)
2184 int i = XVECLEN (x, 0);
2186 for (i--; i >= 0; i--)
2187 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
2188 && GET_CODE (XVECEXP (x, 0, i)) != USE
2189 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
2195 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2196 is not necessarily true for hard registers. */
2197 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
2198 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
2199 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
2202 /* We do not check other CLOBBER or USE here. An insn consisting of just
2203 a CLOBBER or just a USE should not be deleted. */
2207 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2208 return 1 if the entire library call is dead.
2209 This is true if INSN copies a register (hard or pseudo)
2210 and if the hard return reg of the call insn is dead.
2211 (The caller should have tested the destination of the SET inside
2212 INSN already for death.)
2214 If this insn doesn't just copy a register, then we don't
2215 have an ordinary libcall. In that case, cse could not have
2216 managed to substitute the source for the dest later on,
2217 so we can assume the libcall is dead.
2219 PBI is the block info giving pseudoregs live before this insn.
2220 NOTE is the REG_RETVAL note of the insn. */
2223 libcall_dead_p (pbi, note, insn)
2224 struct propagate_block_info *pbi;
2228 rtx x = single_set (insn);
2232 rtx r = SET_SRC (x);
2234 if (GET_CODE (r) == REG)
2236 rtx call = XEXP (note, 0);
2240 /* Find the call insn. */
2241 while (call != insn && GET_CODE (call) != CALL_INSN)
2242 call = NEXT_INSN (call);
2244 /* If there is none, do nothing special,
2245 since ordinary death handling can understand these insns. */
2249 /* See if the hard reg holding the value is dead.
2250 If this is a PARALLEL, find the call within it. */
2251 call_pat = PATTERN (call);
2252 if (GET_CODE (call_pat) == PARALLEL)
2254 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
2255 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
2256 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
2259 /* This may be a library call that is returning a value
2260 via invisible pointer. Do nothing special, since
2261 ordinary death handling can understand these insns. */
2265 call_pat = XVECEXP (call_pat, 0, i);
2268 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
2274 /* Return 1 if register REGNO was used before it was set, i.e. if it is
2275 live at function entry. Don't count global register variables, variables
2276 in registers that can be used for function arg passing, or variables in
2277 fixed hard registers. */
2280 regno_uninitialized (regno)
2283 if (n_basic_blocks == 0
2284 || (regno < FIRST_PSEUDO_REGISTER
2285 && (global_regs[regno]
2286 || fixed_regs[regno]
2287 || FUNCTION_ARG_REGNO_P (regno))))
2290 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
2293 /* 1 if register REGNO was alive at a place where `setjmp' was called
2294 and was set more than once or is an argument.
2295 Such regs may be clobbered by `longjmp'. */
2298 regno_clobbered_at_setjmp (regno)
2301 if (n_basic_blocks == 0)
2304 return ((REG_N_SETS (regno) > 1
2305 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
2306 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
2309 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2310 maximal list size; look for overlaps in mode and select the largest. */
2312 add_to_mem_set_list (pbi, mem)
2313 struct propagate_block_info *pbi;
2318 /* We don't know how large a BLKmode store is, so we must not
2319 take them into consideration. */
2320 if (GET_MODE (mem) == BLKmode)
2323 for (i = pbi->mem_set_list; i ; i = XEXP (i, 1))
2325 rtx e = XEXP (i, 0);
2326 if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0)))
2328 if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e)))
2331 /* If we must store a copy of the mem, we can just modify
2332 the mode of the stored copy. */
2333 if (pbi->flags & PROP_AUTOINC)
2334 PUT_MODE (e, GET_MODE (mem));
2343 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN)
2346 /* Store a copy of mem, otherwise the address may be
2347 scrogged by find_auto_inc. */
2348 if (pbi->flags & PROP_AUTOINC)
2349 mem = shallow_copy_rtx (mem);
2351 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
2352 pbi->mem_set_list_len++;
2356 /* INSN references memory, possibly using autoincrement addressing modes.
2357 Find any entries on the mem_set_list that need to be invalidated due
2358 to an address change. */
2361 invalidate_mems_from_autoinc (pbi, insn)
2362 struct propagate_block_info *pbi;
2365 rtx note = REG_NOTES (insn);
2366 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
2367 if (REG_NOTE_KIND (note) == REG_INC)
2368 invalidate_mems_from_set (pbi, XEXP (note, 0));
2371 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2374 invalidate_mems_from_set (pbi, exp)
2375 struct propagate_block_info *pbi;
2378 rtx temp = pbi->mem_set_list;
2379 rtx prev = NULL_RTX;
2384 next = XEXP (temp, 1);
2385 if (reg_overlap_mentioned_p (exp, XEXP (temp, 0)))
2387 /* Splice this entry out of the list. */
2389 XEXP (prev, 1) = next;
2391 pbi->mem_set_list = next;
2392 free_EXPR_LIST_node (temp);
2393 pbi->mem_set_list_len--;
2401 /* Process the registers that are set within X. Their bits are set to
2402 1 in the regset DEAD, because they are dead prior to this insn.
2404 If INSN is nonzero, it is the insn being processed.
2406 FLAGS is the set of operations to perform. */
2409 mark_set_regs (pbi, x, insn)
2410 struct propagate_block_info *pbi;
2413 rtx cond = NULL_RTX;
2418 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2420 if (REG_NOTE_KIND (link) == REG_INC)
2421 mark_set_1 (pbi, SET, XEXP (link, 0),
2422 (GET_CODE (x) == COND_EXEC
2423 ? COND_EXEC_TEST (x) : NULL_RTX),
2427 switch (code = GET_CODE (x))
2431 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
2435 cond = COND_EXEC_TEST (x);
2436 x = COND_EXEC_CODE (x);
2443 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2445 rtx sub = XVECEXP (x, 0, i);
2446 switch (code = GET_CODE (sub))
2449 if (cond != NULL_RTX)
2452 cond = COND_EXEC_TEST (sub);
2453 sub = COND_EXEC_CODE (sub);
2454 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
2460 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
2475 /* Process a single set, which appears in INSN. REG (which may not
2476 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2477 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2478 If the set is conditional (because it appear in a COND_EXEC), COND
2479 will be the condition. */
2482 mark_set_1 (pbi, code, reg, cond, insn, flags)
2483 struct propagate_block_info *pbi;
2485 rtx reg, cond, insn;
2488 int regno_first = -1, regno_last = -1;
2489 unsigned long not_dead = 0;
2492 /* Modifying just one hardware register of a multi-reg value or just a
2493 byte field of a register does not mean the value from before this insn
2494 is now dead. Of course, if it was dead after it's unused now. */
2496 switch (GET_CODE (reg))
2499 /* Some targets place small structures in registers for return values of
2500 functions. We have to detect this case specially here to get correct
2501 flow information. */
2502 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
2503 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
2504 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
2510 case STRICT_LOW_PART:
2511 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2513 reg = XEXP (reg, 0);
2514 while (GET_CODE (reg) == SUBREG
2515 || GET_CODE (reg) == ZERO_EXTRACT
2516 || GET_CODE (reg) == SIGN_EXTRACT
2517 || GET_CODE (reg) == STRICT_LOW_PART);
2518 if (GET_CODE (reg) == MEM)
2520 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
2524 regno_last = regno_first = REGNO (reg);
2525 if (regno_first < FIRST_PSEUDO_REGISTER)
2526 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
2530 if (GET_CODE (SUBREG_REG (reg)) == REG)
2532 enum machine_mode outer_mode = GET_MODE (reg);
2533 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
2535 /* Identify the range of registers affected. This is moderately
2536 tricky for hard registers. See alter_subreg. */
2538 regno_last = regno_first = REGNO (SUBREG_REG (reg));
2539 if (regno_first < FIRST_PSEUDO_REGISTER)
2541 regno_first += subreg_regno_offset (regno_first, inner_mode,
2544 regno_last = (regno_first
2545 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
2547 /* Since we've just adjusted the register number ranges, make
2548 sure REG matches. Otherwise some_was_live will be clear
2549 when it shouldn't have been, and we'll create incorrect
2550 REG_UNUSED notes. */
2551 reg = gen_rtx_REG (outer_mode, regno_first);
2555 /* If the number of words in the subreg is less than the number
2556 of words in the full register, we have a well-defined partial
2557 set. Otherwise the high bits are undefined.
2559 This is only really applicable to pseudos, since we just took
2560 care of multi-word hard registers. */
2561 if (((GET_MODE_SIZE (outer_mode)
2562 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
2563 < ((GET_MODE_SIZE (inner_mode)
2564 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
2565 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
2568 reg = SUBREG_REG (reg);
2572 reg = SUBREG_REG (reg);
2579 /* If this set is a MEM, then it kills any aliased writes.
2580 If this set is a REG, then it kills any MEMs which use the reg. */
2581 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2583 if (GET_CODE (reg) == REG)
2584 invalidate_mems_from_set (pbi, reg);
2586 /* If the memory reference had embedded side effects (autoincrement
2587 address modes. Then we may need to kill some entries on the
2589 if (insn && GET_CODE (reg) == MEM)
2590 invalidate_mems_from_autoinc (pbi, insn);
2592 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
2593 /* ??? With more effort we could track conditional memory life. */
2595 /* There are no REG_INC notes for SP, so we can't assume we'll see
2596 everything that invalidates it. To be safe, don't eliminate any
2597 stores though SP; none of them should be redundant anyway. */
2598 && ! reg_mentioned_p (stack_pointer_rtx, reg))
2599 add_to_mem_set_list (pbi, canon_rtx (reg));
2602 if (GET_CODE (reg) == REG
2603 && ! (regno_first == FRAME_POINTER_REGNUM
2604 && (! reload_completed || frame_pointer_needed))
2605 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2606 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
2607 && (! reload_completed || frame_pointer_needed))
2609 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2610 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
2614 int some_was_live = 0, some_was_dead = 0;
2616 for (i = regno_first; i <= regno_last; ++i)
2618 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
2621 /* Order of the set operation matters here since both
2622 sets may be the same. */
2623 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
2624 if (cond != NULL_RTX
2625 && ! REGNO_REG_SET_P (pbi->local_set, i))
2626 SET_REGNO_REG_SET (pbi->cond_local_set, i);
2628 SET_REGNO_REG_SET (pbi->local_set, i);
2630 if (code != CLOBBER)
2631 SET_REGNO_REG_SET (pbi->new_set, i);
2633 some_was_live |= needed_regno;
2634 some_was_dead |= ! needed_regno;
2637 #ifdef HAVE_conditional_execution
2638 /* Consider conditional death in deciding that the register needs
2640 if (some_was_live && ! not_dead
2641 /* The stack pointer is never dead. Well, not strictly true,
2642 but it's very difficult to tell from here. Hopefully
2643 combine_stack_adjustments will fix up the most egregious
2645 && regno_first != STACK_POINTER_REGNUM)
2647 for (i = regno_first; i <= regno_last; ++i)
2648 if (! mark_regno_cond_dead (pbi, i, cond))
2649 not_dead |= ((unsigned long) 1) << (i - regno_first);
2653 /* Additional data to record if this is the final pass. */
2654 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
2655 | PROP_DEATH_NOTES | PROP_AUTOINC))
2658 int blocknum = pbi->bb->index;
2661 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2663 y = pbi->reg_next_use[regno_first];
2665 /* The next use is no longer next, since a store intervenes. */
2666 for (i = regno_first; i <= regno_last; ++i)
2667 pbi->reg_next_use[i] = 0;
2670 if (flags & PROP_REG_INFO)
2672 for (i = regno_first; i <= regno_last; ++i)
2674 /* Count (weighted) references, stores, etc. This counts a
2675 register twice if it is modified, but that is correct. */
2676 REG_N_SETS (i) += 1;
2677 REG_N_REFS (i) += 1;
2678 REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb);
2680 /* The insns where a reg is live are normally counted
2681 elsewhere, but we want the count to include the insn
2682 where the reg is set, and the normal counting mechanism
2683 would not count it. */
2684 REG_LIVE_LENGTH (i) += 1;
2687 /* If this is a hard reg, record this function uses the reg. */
2688 if (regno_first < FIRST_PSEUDO_REGISTER)
2690 for (i = regno_first; i <= regno_last; i++)
2691 regs_ever_live[i] = 1;
2695 /* Keep track of which basic blocks each reg appears in. */
2696 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
2697 REG_BASIC_BLOCK (regno_first) = blocknum;
2698 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
2699 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
2703 if (! some_was_dead)
2705 if (flags & PROP_LOG_LINKS)
2707 /* Make a logical link from the next following insn
2708 that uses this register, back to this insn.
2709 The following insns have already been processed.
2711 We don't build a LOG_LINK for hard registers containing
2712 in ASM_OPERANDs. If these registers get replaced,
2713 we might wind up changing the semantics of the insn,
2714 even if reload can make what appear to be valid
2715 assignments later. */
2716 if (y && (BLOCK_NUM (y) == blocknum)
2717 && (regno_first >= FIRST_PSEUDO_REGISTER
2718 || asm_noperands (PATTERN (y)) < 0))
2719 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
2724 else if (! some_was_live)
2726 if (flags & PROP_REG_INFO)
2727 REG_N_DEATHS (regno_first) += 1;
2729 if (flags & PROP_DEATH_NOTES)
2731 /* Note that dead stores have already been deleted
2732 when possible. If we get here, we have found a
2733 dead store that cannot be eliminated (because the
2734 same insn does something useful). Indicate this
2735 by marking the reg being set as dying here. */
2737 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2742 if (flags & PROP_DEATH_NOTES)
2744 /* This is a case where we have a multi-word hard register
2745 and some, but not all, of the words of the register are
2746 needed in subsequent insns. Write REG_UNUSED notes
2747 for those parts that were not needed. This case should
2750 for (i = regno_first; i <= regno_last; ++i)
2751 if (! REGNO_REG_SET_P (pbi->reg_live, i))
2753 = alloc_EXPR_LIST (REG_UNUSED,
2754 gen_rtx_REG (reg_raw_mode[i], i),
2760 /* Mark the register as being dead. */
2762 /* The stack pointer is never dead. Well, not strictly true,
2763 but it's very difficult to tell from here. Hopefully
2764 combine_stack_adjustments will fix up the most egregious
2766 && regno_first != STACK_POINTER_REGNUM)
2768 for (i = regno_first; i <= regno_last; ++i)
2769 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
2770 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
2773 else if (GET_CODE (reg) == REG)
2775 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2776 pbi->reg_next_use[regno_first] = 0;
2779 /* If this is the last pass and this is a SCRATCH, show it will be dying
2780 here and count it. */
2781 else if (GET_CODE (reg) == SCRATCH)
2783 if (flags & PROP_DEATH_NOTES)
2785 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2789 #ifdef HAVE_conditional_execution
2790 /* Mark REGNO conditionally dead.
2791 Return true if the register is now unconditionally dead. */
2794 mark_regno_cond_dead (pbi, regno, cond)
2795 struct propagate_block_info *pbi;
2799 /* If this is a store to a predicate register, the value of the
2800 predicate is changing, we don't know that the predicate as seen
2801 before is the same as that seen after. Flush all dependent
2802 conditions from reg_cond_dead. This will make all such
2803 conditionally live registers unconditionally live. */
2804 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
2805 flush_reg_cond_reg (pbi, regno);
2807 /* If this is an unconditional store, remove any conditional
2808 life that may have existed. */
2809 if (cond == NULL_RTX)
2810 splay_tree_remove (pbi->reg_cond_dead, regno);
2813 splay_tree_node node;
2814 struct reg_cond_life_info *rcli;
2817 /* Otherwise this is a conditional set. Record that fact.
2818 It may have been conditionally used, or there may be a
2819 subsequent set with a complimentary condition. */
2821 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
2824 /* The register was unconditionally live previously.
2825 Record the current condition as the condition under
2826 which it is dead. */
2827 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
2828 rcli->condition = cond;
2829 rcli->stores = cond;
2830 rcli->orig_condition = const0_rtx;
2831 splay_tree_insert (pbi->reg_cond_dead, regno,
2832 (splay_tree_value) rcli);
2834 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2836 /* Not unconditionally dead. */
2841 /* The register was conditionally live previously.
2842 Add the new condition to the old. */
2843 rcli = (struct reg_cond_life_info *) node->value;
2844 ncond = rcli->condition;
2845 ncond = ior_reg_cond (ncond, cond, 1);
2846 if (rcli->stores == const0_rtx)
2847 rcli->stores = cond;
2848 else if (rcli->stores != const1_rtx)
2849 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
2851 /* If the register is now unconditionally dead, remove the entry
2852 in the splay_tree. A register is unconditionally dead if the
2853 dead condition ncond is true. A register is also unconditionally
2854 dead if the sum of all conditional stores is an unconditional
2855 store (stores is true), and the dead condition is identically the
2856 same as the original dead condition initialized at the end of
2857 the block. This is a pointer compare, not an rtx_equal_p
2859 if (ncond == const1_rtx
2860 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
2861 splay_tree_remove (pbi->reg_cond_dead, regno);
2864 rcli->condition = ncond;
2866 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2868 /* Not unconditionally dead. */
2877 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2880 free_reg_cond_life_info (value)
2881 splay_tree_value value;
2883 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
2887 /* Helper function for flush_reg_cond_reg. */
2890 flush_reg_cond_reg_1 (node, data)
2891 splay_tree_node node;
2894 struct reg_cond_life_info *rcli;
2895 int *xdata = (int *) data;
2896 unsigned int regno = xdata[0];
2898 /* Don't need to search if last flushed value was farther on in
2899 the in-order traversal. */
2900 if (xdata[1] >= (int) node->key)
2903 /* Splice out portions of the expression that refer to regno. */
2904 rcli = (struct reg_cond_life_info *) node->value;
2905 rcli->condition = elim_reg_cond (rcli->condition, regno);
2906 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
2907 rcli->stores = elim_reg_cond (rcli->stores, regno);
2909 /* If the entire condition is now false, signal the node to be removed. */
2910 if (rcli->condition == const0_rtx)
2912 xdata[1] = node->key;
2915 else if (rcli->condition == const1_rtx)
2921 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2924 flush_reg_cond_reg (pbi, regno)
2925 struct propagate_block_info *pbi;
2932 while (splay_tree_foreach (pbi->reg_cond_dead,
2933 flush_reg_cond_reg_1, pair) == -1)
2934 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
2936 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
2939 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2940 For ior/and, the ADD flag determines whether we want to add the new
2941 condition X to the old one unconditionally. If it is zero, we will
2942 only return a new expression if X allows us to simplify part of
2943 OLD, otherwise we return NULL to the caller.
2944 If ADD is nonzero, we will return a new condition in all cases. The
2945 toplevel caller of one of these functions should always pass 1 for
2949 ior_reg_cond (old, x, add)
2955 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
2957 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
2958 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
2959 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2961 if (GET_CODE (x) == GET_CODE (old)
2962 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2966 return gen_rtx_IOR (0, old, x);
2969 switch (GET_CODE (old))
2972 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
2973 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
2974 if (op0 != NULL || op1 != NULL)
2976 if (op0 == const0_rtx)
2977 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
2978 if (op1 == const0_rtx)
2979 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
2980 if (op0 == const1_rtx || op1 == const1_rtx)
2983 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
2984 else if (rtx_equal_p (x, op0))
2985 /* (x | A) | x ~ (x | A). */
2988 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
2989 else if (rtx_equal_p (x, op1))
2990 /* (A | x) | x ~ (A | x). */
2992 return gen_rtx_IOR (0, op0, op1);
2996 return gen_rtx_IOR (0, old, x);
2999 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3000 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3001 if (op0 != NULL || op1 != NULL)
3003 if (op0 == const1_rtx)
3004 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3005 if (op1 == const1_rtx)
3006 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3007 if (op0 == const0_rtx || op1 == const0_rtx)
3010 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3011 else if (rtx_equal_p (x, op0))
3012 /* (x & A) | x ~ x. */
3015 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3016 else if (rtx_equal_p (x, op1))
3017 /* (A & x) | x ~ x. */
3019 return gen_rtx_AND (0, op0, op1);
3023 return gen_rtx_IOR (0, old, x);
3026 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3028 return not_reg_cond (op0);
3031 return gen_rtx_IOR (0, old, x);
3042 enum rtx_code x_code;
3044 if (x == const0_rtx)
3046 else if (x == const1_rtx)
3048 x_code = GET_CODE (x);
3051 if (GET_RTX_CLASS (x_code) == '<'
3052 && GET_CODE (XEXP (x, 0)) == REG)
3054 if (XEXP (x, 1) != const0_rtx)
3057 return gen_rtx_fmt_ee (reverse_condition (x_code),
3058 VOIDmode, XEXP (x, 0), const0_rtx);
3060 return gen_rtx_NOT (0, x);
3064 and_reg_cond (old, x, add)
3070 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
3072 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
3073 && GET_CODE (x) == reverse_condition (GET_CODE (old))
3074 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3076 if (GET_CODE (x) == GET_CODE (old)
3077 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3081 return gen_rtx_AND (0, old, x);
3084 switch (GET_CODE (old))
3087 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3088 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3089 if (op0 != NULL || op1 != NULL)
3091 if (op0 == const0_rtx)
3092 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3093 if (op1 == const0_rtx)
3094 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3095 if (op0 == const1_rtx || op1 == const1_rtx)
3098 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3099 else if (rtx_equal_p (x, op0))
3100 /* (x | A) & x ~ x. */
3103 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3104 else if (rtx_equal_p (x, op1))
3105 /* (A | x) & x ~ x. */
3107 return gen_rtx_IOR (0, op0, op1);
3111 return gen_rtx_AND (0, old, x);
3114 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3115 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3116 if (op0 != NULL || op1 != NULL)
3118 if (op0 == const1_rtx)
3119 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3120 if (op1 == const1_rtx)
3121 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3122 if (op0 == const0_rtx || op1 == const0_rtx)
3125 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3126 else if (rtx_equal_p (x, op0))
3127 /* (x & A) & x ~ (x & A). */
3130 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3131 else if (rtx_equal_p (x, op1))
3132 /* (A & x) & x ~ (A & x). */
3134 return gen_rtx_AND (0, op0, op1);
3138 return gen_rtx_AND (0, old, x);
3141 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3143 return not_reg_cond (op0);
3146 return gen_rtx_AND (0, old, x);
3153 /* Given a condition X, remove references to reg REGNO and return the
3154 new condition. The removal will be done so that all conditions
3155 involving REGNO are considered to evaluate to false. This function
3156 is used when the value of REGNO changes. */
3159 elim_reg_cond (x, regno)
3165 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
3167 if (REGNO (XEXP (x, 0)) == regno)
3172 switch (GET_CODE (x))
3175 op0 = elim_reg_cond (XEXP (x, 0), regno);
3176 op1 = elim_reg_cond (XEXP (x, 1), regno);
3177 if (op0 == const0_rtx || op1 == const0_rtx)
3179 if (op0 == const1_rtx)
3181 if (op1 == const1_rtx)
3183 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3185 return gen_rtx_AND (0, op0, op1);
3188 op0 = elim_reg_cond (XEXP (x, 0), regno);
3189 op1 = elim_reg_cond (XEXP (x, 1), regno);
3190 if (op0 == const1_rtx || op1 == const1_rtx)
3192 if (op0 == const0_rtx)
3194 if (op1 == const0_rtx)
3196 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3198 return gen_rtx_IOR (0, op0, op1);
3201 op0 = elim_reg_cond (XEXP (x, 0), regno);
3202 if (op0 == const0_rtx)
3204 if (op0 == const1_rtx)
3206 if (op0 != XEXP (x, 0))
3207 return not_reg_cond (op0);
3214 #endif /* HAVE_conditional_execution */
3218 /* Try to substitute the auto-inc expression INC as the address inside
3219 MEM which occurs in INSN. Currently, the address of MEM is an expression
3220 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3221 that has a single set whose source is a PLUS of INCR_REG and something
3225 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
3226 struct propagate_block_info *pbi;
3227 rtx inc, insn, mem, incr, incr_reg;
3229 int regno = REGNO (incr_reg);
3230 rtx set = single_set (incr);
3231 rtx q = SET_DEST (set);
3232 rtx y = SET_SRC (set);
3233 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
3235 /* Make sure this reg appears only once in this insn. */
3236 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
3239 if (dead_or_set_p (incr, incr_reg)
3240 /* Mustn't autoinc an eliminable register. */
3241 && (regno >= FIRST_PSEUDO_REGISTER
3242 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
3244 /* This is the simple case. Try to make the auto-inc. If
3245 we can't, we are done. Otherwise, we will do any
3246 needed updates below. */
3247 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
3250 else if (GET_CODE (q) == REG
3251 /* PREV_INSN used here to check the semi-open interval
3253 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
3254 /* We must also check for sets of q as q may be
3255 a call clobbered hard register and there may
3256 be a call between PREV_INSN (insn) and incr. */
3257 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
3259 /* We have *p followed sometime later by q = p+size.
3260 Both p and q must be live afterward,
3261 and q is not used between INSN and its assignment.
3262 Change it to q = p, ...*q..., q = q+size.
3263 Then fall into the usual case. */
3267 emit_move_insn (q, incr_reg);
3268 insns = get_insns ();
3271 /* If we can't make the auto-inc, or can't make the
3272 replacement into Y, exit. There's no point in making
3273 the change below if we can't do the auto-inc and doing
3274 so is not correct in the pre-inc case. */
3277 validate_change (insn, &XEXP (mem, 0), inc, 1);
3278 validate_change (incr, &XEXP (y, opnum), q, 1);
3279 if (! apply_change_group ())
3282 /* We now know we'll be doing this change, so emit the
3283 new insn(s) and do the updates. */
3284 emit_insns_before (insns, insn);
3286 if (pbi->bb->head == insn)
3287 pbi->bb->head = insns;
3289 /* INCR will become a NOTE and INSN won't contain a
3290 use of INCR_REG. If a use of INCR_REG was just placed in
3291 the insn before INSN, make that the next use.
3292 Otherwise, invalidate it. */
3293 if (GET_CODE (PREV_INSN (insn)) == INSN
3294 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
3295 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
3296 pbi->reg_next_use[regno] = PREV_INSN (insn);
3298 pbi->reg_next_use[regno] = 0;
3303 /* REGNO is now used in INCR which is below INSN, but
3304 it previously wasn't live here. If we don't mark
3305 it as live, we'll put a REG_DEAD note for it
3306 on this insn, which is incorrect. */
3307 SET_REGNO_REG_SET (pbi->reg_live, regno);
3309 /* If there are any calls between INSN and INCR, show
3310 that REGNO now crosses them. */
3311 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
3312 if (GET_CODE (temp) == CALL_INSN)
3313 REG_N_CALLS_CROSSED (regno)++;
3315 /* Invalidate alias info for Q since we just changed its value. */
3316 clear_reg_alias_info (q);
3321 /* If we haven't returned, it means we were able to make the
3322 auto-inc, so update the status. First, record that this insn
3323 has an implicit side effect. */
3325 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
3327 /* Modify the old increment-insn to simply copy
3328 the already-incremented value of our register. */
3329 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
3332 /* If that makes it a no-op (copying the register into itself) delete
3333 it so it won't appear to be a "use" and a "set" of this
3335 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
3337 /* If the original source was dead, it's dead now. */
3340 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
3342 remove_note (incr, note);
3343 if (XEXP (note, 0) != incr_reg)
3344 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
3347 PUT_CODE (incr, NOTE);
3348 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
3349 NOTE_SOURCE_FILE (incr) = 0;
3352 if (regno >= FIRST_PSEUDO_REGISTER)
3354 /* Count an extra reference to the reg. When a reg is
3355 incremented, spilling it is worse, so we want to make
3356 that less likely. */
3357 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3359 /* Count the increment as a setting of the register,
3360 even though it isn't a SET in rtl. */
3361 REG_N_SETS (regno)++;
3365 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3369 find_auto_inc (pbi, x, insn)
3370 struct propagate_block_info *pbi;
3374 rtx addr = XEXP (x, 0);
3375 HOST_WIDE_INT offset = 0;
3376 rtx set, y, incr, inc_val;
3378 int size = GET_MODE_SIZE (GET_MODE (x));
3380 if (GET_CODE (insn) == JUMP_INSN)
3383 /* Here we detect use of an index register which might be good for
3384 postincrement, postdecrement, preincrement, or predecrement. */
3386 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
3387 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
3389 if (GET_CODE (addr) != REG)
3392 regno = REGNO (addr);
3394 /* Is the next use an increment that might make auto-increment? */
3395 incr = pbi->reg_next_use[regno];
3396 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
3398 set = single_set (incr);
3399 if (set == 0 || GET_CODE (set) != SET)
3403 if (GET_CODE (y) != PLUS)
3406 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
3407 inc_val = XEXP (y, 1);
3408 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
3409 inc_val = XEXP (y, 0);
3413 if (GET_CODE (inc_val) == CONST_INT)
3415 if (HAVE_POST_INCREMENT
3416 && (INTVAL (inc_val) == size && offset == 0))
3417 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
3419 else if (HAVE_POST_DECREMENT
3420 && (INTVAL (inc_val) == -size && offset == 0))
3421 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
3423 else if (HAVE_PRE_INCREMENT
3424 && (INTVAL (inc_val) == size && offset == size))
3425 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
3427 else if (HAVE_PRE_DECREMENT
3428 && (INTVAL (inc_val) == -size && offset == -size))
3429 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
3431 else if (HAVE_POST_MODIFY_DISP && offset == 0)
3432 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3433 gen_rtx_PLUS (Pmode,
3436 insn, x, incr, addr);
3438 else if (GET_CODE (inc_val) == REG
3439 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
3443 if (HAVE_POST_MODIFY_REG && offset == 0)
3444 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3445 gen_rtx_PLUS (Pmode,
3448 insn, x, incr, addr);
3452 #endif /* AUTO_INC_DEC */
3455 mark_used_reg (pbi, reg, cond, insn)
3456 struct propagate_block_info *pbi;
3458 rtx cond ATTRIBUTE_UNUSED;
3461 unsigned int regno_first, regno_last, i;
3462 int some_was_live, some_was_dead, some_not_set;
3464 regno_last = regno_first = REGNO (reg);
3465 if (regno_first < FIRST_PSEUDO_REGISTER)
3466 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
3468 /* Find out if any of this register is live after this instruction. */
3469 some_was_live = some_was_dead = 0;
3470 for (i = regno_first; i <= regno_last; ++i)
3472 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
3473 some_was_live |= needed_regno;
3474 some_was_dead |= ! needed_regno;
3477 /* Find out if any of the register was set this insn. */
3479 for (i = regno_first; i <= regno_last; ++i)
3480 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
3482 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3484 /* Record where each reg is used, so when the reg is set we know
3485 the next insn that uses it. */
3486 pbi->reg_next_use[regno_first] = insn;
3489 if (pbi->flags & PROP_REG_INFO)
3491 if (regno_first < FIRST_PSEUDO_REGISTER)
3493 /* If this is a register we are going to try to eliminate,
3494 don't mark it live here. If we are successful in
3495 eliminating it, it need not be live unless it is used for
3496 pseudos, in which case it will have been set live when it
3497 was allocated to the pseudos. If the register will not
3498 be eliminated, reload will set it live at that point.
3500 Otherwise, record that this function uses this register. */
3501 /* ??? The PPC backend tries to "eliminate" on the pic
3502 register to itself. This should be fixed. In the mean
3503 time, hack around it. */
3505 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
3506 && (regno_first == FRAME_POINTER_REGNUM
3507 || regno_first == ARG_POINTER_REGNUM)))
3508 for (i = regno_first; i <= regno_last; ++i)
3509 regs_ever_live[i] = 1;
3513 /* Keep track of which basic block each reg appears in. */
3515 int blocknum = pbi->bb->index;
3516 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
3517 REG_BASIC_BLOCK (regno_first) = blocknum;
3518 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
3519 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
3521 /* Count (weighted) number of uses of each reg. */
3522 REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb);
3523 REG_N_REFS (regno_first)++;
3527 /* Record and count the insns in which a reg dies. If it is used in
3528 this insn and was dead below the insn then it dies in this insn.
3529 If it was set in this insn, we do not make a REG_DEAD note;
3530 likewise if we already made such a note. */
3531 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
3535 /* Check for the case where the register dying partially
3536 overlaps the register set by this insn. */
3537 if (regno_first != regno_last)
3538 for (i = regno_first; i <= regno_last; ++i)
3539 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
3541 /* If none of the words in X is needed, make a REG_DEAD note.
3542 Otherwise, we must make partial REG_DEAD notes. */
3543 if (! some_was_live)
3545 if ((pbi->flags & PROP_DEATH_NOTES)
3546 && ! find_regno_note (insn, REG_DEAD, regno_first))
3548 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
3550 if (pbi->flags & PROP_REG_INFO)
3551 REG_N_DEATHS (regno_first)++;
3555 /* Don't make a REG_DEAD note for a part of a register
3556 that is set in the insn. */
3557 for (i = regno_first; i <= regno_last; ++i)
3558 if (! REGNO_REG_SET_P (pbi->reg_live, i)
3559 && ! dead_or_set_regno_p (insn, i))
3561 = alloc_EXPR_LIST (REG_DEAD,
3562 gen_rtx_REG (reg_raw_mode[i], i),
3567 /* Mark the register as being live. */
3568 for (i = regno_first; i <= regno_last; ++i)
3570 SET_REGNO_REG_SET (pbi->reg_live, i);
3572 #ifdef HAVE_conditional_execution
3573 /* If this is a conditional use, record that fact. If it is later
3574 conditionally set, we'll know to kill the register. */
3575 if (cond != NULL_RTX)
3577 splay_tree_node node;
3578 struct reg_cond_life_info *rcli;
3583 node = splay_tree_lookup (pbi->reg_cond_dead, i);
3586 /* The register was unconditionally live previously.
3587 No need to do anything. */
3591 /* The register was conditionally live previously.
3592 Subtract the new life cond from the old death cond. */
3593 rcli = (struct reg_cond_life_info *) node->value;
3594 ncond = rcli->condition;
3595 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
3597 /* If the register is now unconditionally live,
3598 remove the entry in the splay_tree. */
3599 if (ncond == const0_rtx)
3600 splay_tree_remove (pbi->reg_cond_dead, i);
3603 rcli->condition = ncond;
3604 SET_REGNO_REG_SET (pbi->reg_cond_reg,
3605 REGNO (XEXP (cond, 0)));
3611 /* The register was not previously live at all. Record
3612 the condition under which it is still dead. */
3613 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
3614 rcli->condition = not_reg_cond (cond);
3615 rcli->stores = const0_rtx;
3616 rcli->orig_condition = const0_rtx;
3617 splay_tree_insert (pbi->reg_cond_dead, i,
3618 (splay_tree_value) rcli);
3620 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
3623 else if (some_was_live)
3625 /* The register may have been conditionally live previously, but
3626 is now unconditionally live. Remove it from the conditionally
3627 dead list, so that a conditional set won't cause us to think
3629 splay_tree_remove (pbi->reg_cond_dead, i);
3635 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3636 This is done assuming the registers needed from X are those that
3637 have 1-bits in PBI->REG_LIVE.
3639 INSN is the containing instruction. If INSN is dead, this function
3643 mark_used_regs (pbi, x, cond, insn)
3644 struct propagate_block_info *pbi;
3649 int flags = pbi->flags;
3654 code = GET_CODE (x);
3675 /* If we are clobbering a MEM, mark any registers inside the address
3677 if (GET_CODE (XEXP (x, 0)) == MEM)
3678 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
3682 /* Don't bother watching stores to mems if this is not the
3683 final pass. We'll not be deleting dead stores this round. */
3684 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
3686 /* Invalidate the data for the last MEM stored, but only if MEM is
3687 something that can be stored into. */
3688 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3689 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3690 /* Needn't clear the memory set list. */
3694 rtx temp = pbi->mem_set_list;
3695 rtx prev = NULL_RTX;
3700 next = XEXP (temp, 1);
3701 if (anti_dependence (XEXP (temp, 0), x))
3703 /* Splice temp out of the list. */
3705 XEXP (prev, 1) = next;
3707 pbi->mem_set_list = next;
3708 free_EXPR_LIST_node (temp);
3709 pbi->mem_set_list_len--;
3717 /* If the memory reference had embedded side effects (autoincrement
3718 address modes. Then we may need to kill some entries on the
3721 invalidate_mems_from_autoinc (pbi, insn);
3725 if (flags & PROP_AUTOINC)
3726 find_auto_inc (pbi, x, insn);
3731 #ifdef CLASS_CANNOT_CHANGE_MODE
3732 if (GET_CODE (SUBREG_REG (x)) == REG
3733 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
3734 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
3735 GET_MODE (SUBREG_REG (x))))
3736 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
3739 /* While we're here, optimize this case. */
3741 if (GET_CODE (x) != REG)
3746 /* See a register other than being set => mark it as needed. */
3747 mark_used_reg (pbi, x, cond, insn);
3752 rtx testreg = SET_DEST (x);
3755 /* If storing into MEM, don't show it as being used. But do
3756 show the address as being used. */
3757 if (GET_CODE (testreg) == MEM)
3760 if (flags & PROP_AUTOINC)
3761 find_auto_inc (pbi, testreg, insn);
3763 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
3764 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3768 /* Storing in STRICT_LOW_PART is like storing in a reg
3769 in that this SET might be dead, so ignore it in TESTREG.
3770 but in some other ways it is like using the reg.
3772 Storing in a SUBREG or a bit field is like storing the entire
3773 register in that if the register's value is not used
3774 then this SET is not needed. */
3775 while (GET_CODE (testreg) == STRICT_LOW_PART
3776 || GET_CODE (testreg) == ZERO_EXTRACT
3777 || GET_CODE (testreg) == SIGN_EXTRACT
3778 || GET_CODE (testreg) == SUBREG)
3780 #ifdef CLASS_CANNOT_CHANGE_MODE
3781 if (GET_CODE (testreg) == SUBREG
3782 && GET_CODE (SUBREG_REG (testreg)) == REG
3783 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
3784 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
3785 GET_MODE (testreg)))
3786 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
3789 /* Modifying a single register in an alternate mode
3790 does not use any of the old value. But these other
3791 ways of storing in a register do use the old value. */
3792 if (GET_CODE (testreg) == SUBREG
3793 && !((REG_BYTES (SUBREG_REG (testreg))
3794 + UNITS_PER_WORD - 1) / UNITS_PER_WORD
3795 > (REG_BYTES (testreg)
3796 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
3801 testreg = XEXP (testreg, 0);
3804 /* If this is a store into a register or group of registers,
3805 recursively scan the value being stored. */
3807 if ((GET_CODE (testreg) == PARALLEL
3808 && GET_MODE (testreg) == BLKmode)
3809 || (GET_CODE (testreg) == REG
3810 && (regno = REGNO (testreg),
3811 ! (regno == FRAME_POINTER_REGNUM
3812 && (! reload_completed || frame_pointer_needed)))
3813 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3814 && ! (regno == HARD_FRAME_POINTER_REGNUM
3815 && (! reload_completed || frame_pointer_needed))
3817 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3818 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
3823 mark_used_regs (pbi, SET_DEST (x), cond, insn);
3824 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3831 case UNSPEC_VOLATILE:
3835 /* Traditional and volatile asm instructions must be considered to use
3836 and clobber all hard registers, all pseudo-registers and all of
3837 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3839 Consider for instance a volatile asm that changes the fpu rounding
3840 mode. An insn should not be moved across this even if it only uses
3841 pseudo-regs because it might give an incorrectly rounded result.
3843 ?!? Unfortunately, marking all hard registers as live causes massive
3844 problems for the register allocator and marking all pseudos as live
3845 creates mountains of uninitialized variable warnings.
3847 So for now, just clear the memory set list and mark any regs
3848 we can find in ASM_OPERANDS as used. */
3849 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
3851 free_EXPR_LIST_list (&pbi->mem_set_list);
3852 pbi->mem_set_list_len = 0;
3855 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3856 We can not just fall through here since then we would be confused
3857 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3858 traditional asms unlike their normal usage. */
3859 if (code == ASM_OPERANDS)
3863 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
3864 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
3870 if (cond != NULL_RTX)
3873 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
3875 cond = COND_EXEC_TEST (x);
3876 x = COND_EXEC_CODE (x);
3880 /* We _do_not_ want to scan operands of phi nodes. Operands of
3881 a phi function are evaluated only when control reaches this
3882 block along a particular edge. Therefore, regs that appear
3883 as arguments to phi should not be added to the global live at
3891 /* Recursively scan the operands of this expression. */
3894 const char * const fmt = GET_RTX_FORMAT (code);
3897 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3901 /* Tail recursive case: save a function call level. */
3907 mark_used_regs (pbi, XEXP (x, i), cond, insn);
3909 else if (fmt[i] == 'E')
3912 for (j = 0; j < XVECLEN (x, i); j++)
3913 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
3922 try_pre_increment_1 (pbi, insn)
3923 struct propagate_block_info *pbi;
3926 /* Find the next use of this reg. If in same basic block,
3927 make it do pre-increment or pre-decrement if appropriate. */
3928 rtx x = single_set (insn);
3929 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
3930 * INTVAL (XEXP (SET_SRC (x), 1)));
3931 int regno = REGNO (SET_DEST (x));
3932 rtx y = pbi->reg_next_use[regno];
3934 && SET_DEST (x) != stack_pointer_rtx
3935 && BLOCK_NUM (y) == BLOCK_NUM (insn)
3936 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3937 mode would be better. */
3938 && ! dead_or_set_p (y, SET_DEST (x))
3939 && try_pre_increment (y, SET_DEST (x), amount))
3941 /* We have found a suitable auto-increment and already changed
3942 insn Y to do it. So flush this increment instruction. */
3943 propagate_block_delete_insn (pbi->bb, insn);
3945 /* Count a reference to this reg for the increment insn we are
3946 deleting. When a reg is incremented, spilling it is worse,
3947 so we want to make that less likely. */
3948 if (regno >= FIRST_PSEUDO_REGISTER)
3950 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3951 REG_N_SETS (regno)++;
3954 /* Flush any remembered memories depending on the value of
3955 the incremented register. */
3956 invalidate_mems_from_set (pbi, SET_DEST (x));
3963 /* Try to change INSN so that it does pre-increment or pre-decrement
3964 addressing on register REG in order to add AMOUNT to REG.
3965 AMOUNT is negative for pre-decrement.
3966 Returns 1 if the change could be made.
3967 This checks all about the validity of the result of modifying INSN. */
3970 try_pre_increment (insn, reg, amount)
3972 HOST_WIDE_INT amount;
3976 /* Nonzero if we can try to make a pre-increment or pre-decrement.
3977 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
3979 /* Nonzero if we can try to make a post-increment or post-decrement.
3980 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
3981 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
3982 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
3985 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
3988 /* From the sign of increment, see which possibilities are conceivable
3989 on this target machine. */
3990 if (HAVE_PRE_INCREMENT && amount > 0)
3992 if (HAVE_POST_INCREMENT && amount > 0)
3995 if (HAVE_PRE_DECREMENT && amount < 0)
3997 if (HAVE_POST_DECREMENT && amount < 0)
4000 if (! (pre_ok || post_ok))
4003 /* It is not safe to add a side effect to a jump insn
4004 because if the incremented register is spilled and must be reloaded
4005 there would be no way to store the incremented value back in memory. */
4007 if (GET_CODE (insn) == JUMP_INSN)
4012 use = find_use_as_address (PATTERN (insn), reg, 0);
4013 if (post_ok && (use == 0 || use == (rtx) (size_t) 1))
4015 use = find_use_as_address (PATTERN (insn), reg, -amount);
4019 if (use == 0 || use == (rtx) (size_t) 1)
4022 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
4025 /* See if this combination of instruction and addressing mode exists. */
4026 if (! validate_change (insn, &XEXP (use, 0),
4027 gen_rtx_fmt_e (amount > 0
4028 ? (do_post ? POST_INC : PRE_INC)
4029 : (do_post ? POST_DEC : PRE_DEC),
4033 /* Record that this insn now has an implicit side effect on X. */
4034 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
4038 #endif /* AUTO_INC_DEC */
4040 /* Find the place in the rtx X where REG is used as a memory address.
4041 Return the MEM rtx that so uses it.
4042 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4043 (plus REG (const_int PLUSCONST)).
4045 If such an address does not appear, return 0.
4046 If REG appears more than once, or is used other than in such an address,
4050 find_use_as_address (x, reg, plusconst)
4053 HOST_WIDE_INT plusconst;
4055 enum rtx_code code = GET_CODE (x);
4056 const char * const fmt = GET_RTX_FORMAT (code);
4061 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
4064 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
4065 && XEXP (XEXP (x, 0), 0) == reg
4066 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
4067 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
4070 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
4072 /* If REG occurs inside a MEM used in a bit-field reference,
4073 that is unacceptable. */
4074 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
4075 return (rtx) (size_t) 1;
4079 return (rtx) (size_t) 1;
4081 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4085 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
4089 return (rtx) (size_t) 1;
4091 else if (fmt[i] == 'E')
4094 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4096 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
4100 return (rtx) (size_t) 1;
4108 /* Write information about registers and basic blocks into FILE.
4109 This is part of making a debugging dump. */
4112 dump_regset (r, outf)
4119 fputs (" (nil)", outf);
4123 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
4125 fprintf (outf, " %d", i);
4126 if (i < FIRST_PSEUDO_REGISTER)
4127 fprintf (outf, " [%s]",
4132 /* Print a human-reaable representation of R on the standard error
4133 stream. This function is designed to be used from within the
4140 dump_regset (r, stderr);
4141 putc ('\n', stderr);
4144 /* Recompute register set/reference counts immediately prior to register
4147 This avoids problems with set/reference counts changing to/from values
4148 which have special meanings to the register allocators.
4150 Additionally, the reference counts are the primary component used by the
4151 register allocators to prioritize pseudos for allocation to hard regs.
4152 More accurate reference counts generally lead to better register allocation.
4154 F is the first insn to be scanned.
4156 LOOP_STEP denotes how much loop_depth should be incremented per
4157 loop nesting level in order to increase the ref count more for
4158 references in a loop.
4160 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4161 possibly other information which is used by the register allocators. */
4164 recompute_reg_usage (f, loop_step)
4165 rtx f ATTRIBUTE_UNUSED;
4166 int loop_step ATTRIBUTE_UNUSED;
4168 allocate_reg_life_data ();
4169 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
4172 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4173 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4174 of the number of registers that died. */
4177 count_or_remove_death_notes (blocks, kill)
4183 for (i = n_basic_blocks - 1; i >= 0; --i)
4188 if (blocks && ! TEST_BIT (blocks, i))
4191 bb = BASIC_BLOCK (i);
4193 for (insn = bb->head;; insn = NEXT_INSN (insn))
4197 rtx *pprev = ®_NOTES (insn);
4202 switch (REG_NOTE_KIND (link))
4205 if (GET_CODE (XEXP (link, 0)) == REG)
4207 rtx reg = XEXP (link, 0);
4210 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
4213 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
4221 rtx next = XEXP (link, 1);
4222 free_EXPR_LIST_node (link);
4223 *pprev = link = next;
4229 pprev = &XEXP (link, 1);
4236 if (insn == bb->end)
4243 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4244 if blocks is NULL. */
4247 clear_log_links (blocks)
4255 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4257 free_INSN_LIST_list (&LOG_LINKS (insn));
4260 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4262 basic_block bb = BASIC_BLOCK (i);
4264 for (insn = bb->head; insn != NEXT_INSN (bb->end);
4265 insn = NEXT_INSN (insn))
4267 free_INSN_LIST_list (&LOG_LINKS (insn));
4271 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4272 correspond to the hard registers, if any, set in that map. This
4273 could be done far more efficiently by having all sorts of special-cases
4274 with moving single words, but probably isn't worth the trouble. */
4277 reg_set_to_hard_reg_set (to, from)
4283 EXECUTE_IF_SET_IN_BITMAP
4286 if (i >= FIRST_PSEUDO_REGISTER)
4288 SET_HARD_REG_BIT (*to, i);