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 delete_dead_jumptables PARAMS ((void));
340 static void clear_log_links PARAMS ((sbitmap));
344 check_function_return_warnings ()
346 if (warn_missing_noreturn
347 && !TREE_THIS_VOLATILE (cfun->decl)
348 && EXIT_BLOCK_PTR->pred == NULL
349 && (lang_missing_noreturn_ok_p
350 && !lang_missing_noreturn_ok_p (cfun->decl)))
351 warning ("function might be possible candidate for attribute `noreturn'");
353 /* If we have a path to EXIT, then we do return. */
354 if (TREE_THIS_VOLATILE (cfun->decl)
355 && EXIT_BLOCK_PTR->pred != NULL)
356 warning ("`noreturn' function does return");
358 /* If the clobber_return_insn appears in some basic block, then we
359 do reach the end without returning a value. */
360 else if (warn_return_type
361 && cfun->x_clobber_return_insn != NULL
362 && EXIT_BLOCK_PTR->pred != NULL)
364 int max_uid = get_max_uid ();
366 /* If clobber_return_insn was excised by jump1, then renumber_insns
367 can make max_uid smaller than the number still recorded in our rtx.
368 That's fine, since this is a quick way of verifying that the insn
369 is no longer in the chain. */
370 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
372 /* Recompute insn->block mapping, since the initial mapping is
373 set before we delete unreachable blocks. */
374 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL)
375 warning ("control reaches end of non-void function");
380 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
381 note associated with the BLOCK. */
384 first_insn_after_basic_block_note (block)
389 /* Get the first instruction in the block. */
392 if (insn == NULL_RTX)
394 if (GET_CODE (insn) == CODE_LABEL)
395 insn = NEXT_INSN (insn);
396 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
399 return NEXT_INSN (insn);
402 /* Perform data flow analysis.
403 F is the first insn of the function; FLAGS is a set of PROP_* flags
404 to be used in accumulating flow info. */
407 life_analysis (f, file, flags)
412 #ifdef ELIMINABLE_REGS
414 static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS;
417 /* Record which registers will be eliminated. We use this in
420 CLEAR_HARD_REG_SET (elim_reg_set);
422 #ifdef ELIMINABLE_REGS
423 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
424 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
426 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
430 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES);
432 /* The post-reload life analysis have (on a global basis) the same
433 registers live as was computed by reload itself. elimination
434 Otherwise offsets and such may be incorrect.
436 Reload will make some registers as live even though they do not
439 We don't want to create new auto-incs after reload, since they
440 are unlikely to be useful and can cause problems with shared
442 if (reload_completed)
443 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
445 /* We want alias analysis information for local dead store elimination. */
446 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
447 init_alias_analysis ();
449 /* Always remove no-op moves. Do this before other processing so
450 that we don't have to keep re-scanning them. */
451 delete_noop_moves (f);
452 purge_all_dead_edges (false);
454 /* Some targets can emit simpler epilogues if they know that sp was
455 not ever modified during the function. After reload, of course,
456 we've already emitted the epilogue so there's no sense searching. */
457 if (! reload_completed)
458 notice_stack_pointer_modification (f);
460 /* Allocate and zero out data structures that will record the
461 data from lifetime analysis. */
462 allocate_reg_life_data ();
463 allocate_bb_life_data ();
465 /* Find the set of registers live on function exit. */
466 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
468 /* "Update" life info from zero. It'd be nice to begin the
469 relaxation with just the exit and noreturn blocks, but that set
470 is not immediately handy. */
472 if (flags & PROP_REG_INFO)
473 memset (regs_ever_live, 0, sizeof (regs_ever_live));
474 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
477 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
478 end_alias_analysis ();
481 dump_flow_info (file);
483 free_basic_block_vars (1);
485 #ifdef ENABLE_CHECKING
489 /* Search for any REG_LABEL notes which reference deleted labels. */
490 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
492 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
494 if (inote && GET_CODE (inote) == NOTE_INSN_DELETED_LABEL)
499 /* Removing dead insns should've made jumptables really dead. */
500 delete_dead_jumptables ();
503 /* A subroutine of verify_wide_reg, called through for_each_rtx.
504 Search for REGNO. If found, return 2 if it is not wider than
508 verify_wide_reg_1 (px, pregno)
513 unsigned int regno = *(int *) pregno;
515 if (GET_CODE (x) == REG && REGNO (x) == regno)
517 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
524 /* A subroutine of verify_local_live_at_start. Search through insns
525 of BB looking for register REGNO. */
528 verify_wide_reg (regno, bb)
532 rtx head = bb->head, end = bb->end;
538 int r = for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no);
546 head = NEXT_INSN (head);
551 fprintf (rtl_dump_file, "Register %d died unexpectedly.\n", regno);
552 dump_bb (bb, rtl_dump_file);
557 /* A subroutine of update_life_info. Verify that there are no untoward
558 changes in live_at_start during a local update. */
561 verify_local_live_at_start (new_live_at_start, bb)
562 regset new_live_at_start;
565 if (reload_completed)
567 /* After reload, there are no pseudos, nor subregs of multi-word
568 registers. The regsets should exactly match. */
569 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
573 fprintf (rtl_dump_file,
574 "live_at_start mismatch in bb %d, aborting\nNew:\n",
576 debug_bitmap_file (rtl_dump_file, new_live_at_start);
577 fputs ("Old:\n", rtl_dump_file);
578 dump_bb (bb, rtl_dump_file);
587 /* Find the set of changed registers. */
588 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
590 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
592 /* No registers should die. */
593 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
597 fprintf (rtl_dump_file,
598 "Register %d died unexpectedly.\n", i);
599 dump_bb (bb, rtl_dump_file);
604 /* Verify that the now-live register is wider than word_mode. */
605 verify_wide_reg (i, bb);
610 /* Updates life information starting with the basic blocks set in BLOCKS.
611 If BLOCKS is null, consider it to be the universal set.
613 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
614 we are only expecting local modifications to basic blocks. If we find
615 extra registers live at the beginning of a block, then we either killed
616 useful data, or we have a broken split that wants data not provided.
617 If we find registers removed from live_at_start, that means we have
618 a broken peephole that is killing a register it shouldn't.
620 ??? This is not true in one situation -- when a pre-reload splitter
621 generates subregs of a multi-word pseudo, current life analysis will
622 lose the kill. So we _can_ have a pseudo go live. How irritating.
624 Including PROP_REG_INFO does not properly refresh regs_ever_live
625 unless the caller resets it to zero. */
628 update_life_info (blocks, extent, prop_flags)
630 enum update_life_extent extent;
634 regset_head tmp_head;
637 tmp = INITIALIZE_REG_SET (tmp_head);
639 timevar_push ((extent == UPDATE_LIFE_LOCAL || blocks)
640 ? TV_LIFE_UPDATE : TV_LIFE);
642 /* Changes to the CFG are only allowed when
643 doing a global update for the entire CFG. */
644 if ((prop_flags & PROP_ALLOW_CFG_CHANGES)
645 && (extent == UPDATE_LIFE_LOCAL || blocks))
648 /* For a global update, we go through the relaxation process again. */
649 if (extent != UPDATE_LIFE_LOCAL)
655 calculate_global_regs_live (blocks, blocks,
656 prop_flags & (PROP_SCAN_DEAD_CODE
657 | PROP_ALLOW_CFG_CHANGES));
659 if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
660 != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
663 /* Removing dead code may allow the CFG to be simplified which
664 in turn may allow for further dead code detection / removal. */
665 for (i = n_basic_blocks - 1; i >= 0; --i)
667 basic_block bb = BASIC_BLOCK (i);
669 COPY_REG_SET (tmp, bb->global_live_at_end);
670 changed |= propagate_block (bb, tmp, NULL, NULL,
671 prop_flags & (PROP_SCAN_DEAD_CODE
672 | PROP_KILL_DEAD_CODE));
675 if (! changed || ! cleanup_cfg (CLEANUP_EXPENSIVE))
679 /* If asked, remove notes from the blocks we'll update. */
680 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
681 count_or_remove_death_notes (blocks, 1);
684 /* Clear log links in case we are asked to (re)compute them. */
685 if (prop_flags & PROP_LOG_LINKS)
686 clear_log_links (blocks);
690 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
692 basic_block bb = BASIC_BLOCK (i);
694 COPY_REG_SET (tmp, bb->global_live_at_end);
695 propagate_block (bb, tmp, NULL, NULL, prop_flags);
697 if (extent == UPDATE_LIFE_LOCAL)
698 verify_local_live_at_start (tmp, bb);
703 for (i = n_basic_blocks - 1; i >= 0; --i)
705 basic_block bb = BASIC_BLOCK (i);
707 COPY_REG_SET (tmp, bb->global_live_at_end);
708 propagate_block (bb, tmp, NULL, NULL, prop_flags);
710 if (extent == UPDATE_LIFE_LOCAL)
711 verify_local_live_at_start (tmp, bb);
717 if (prop_flags & PROP_REG_INFO)
719 /* The only pseudos that are live at the beginning of the function
720 are those that were not set anywhere in the function. local-alloc
721 doesn't know how to handle these correctly, so mark them as not
722 local to any one basic block. */
723 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
724 FIRST_PSEUDO_REGISTER, i,
725 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
727 /* We have a problem with any pseudoreg that lives across the setjmp.
728 ANSI says that if a user variable does not change in value between
729 the setjmp and the longjmp, then the longjmp preserves it. This
730 includes longjmp from a place where the pseudo appears dead.
731 (In principle, the value still exists if it is in scope.)
732 If the pseudo goes in a hard reg, some other value may occupy
733 that hard reg where this pseudo is dead, thus clobbering the pseudo.
734 Conclusion: such a pseudo must not go in a hard reg. */
735 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
736 FIRST_PSEUDO_REGISTER, i,
738 if (regno_reg_rtx[i] != 0)
740 REG_LIVE_LENGTH (i) = -1;
741 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
745 timevar_pop ((extent == UPDATE_LIFE_LOCAL || blocks)
746 ? TV_LIFE_UPDATE : TV_LIFE);
749 /* Update life information in all blocks where BB_DIRTY is set. */
752 update_life_info_in_dirty_blocks (extent, prop_flags)
753 enum update_life_extent extent;
756 sbitmap update_life_blocks = sbitmap_alloc (n_basic_blocks);
760 sbitmap_zero (update_life_blocks);
761 for (block_num = 0; block_num < n_basic_blocks; block_num++)
762 if (BASIC_BLOCK (block_num)->flags & BB_DIRTY)
764 SET_BIT (update_life_blocks, block_num);
769 update_life_info (update_life_blocks, extent, prop_flags);
771 sbitmap_free (update_life_blocks);
774 /* Free the variables allocated by find_basic_blocks.
776 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
779 free_basic_block_vars (keep_head_end_p)
782 if (! keep_head_end_p)
784 if (basic_block_info)
787 VARRAY_FREE (basic_block_info);
791 ENTRY_BLOCK_PTR->aux = NULL;
792 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
793 EXIT_BLOCK_PTR->aux = NULL;
794 EXIT_BLOCK_PTR->global_live_at_start = NULL;
798 /* Delete any insns that copy a register to itself. */
801 delete_noop_moves (f)
802 rtx f ATTRIBUTE_UNUSED;
808 for (i = 0; i < n_basic_blocks; i++)
810 bb = BASIC_BLOCK (i);
811 for (insn = bb->head; insn != NEXT_INSN (bb->end); insn = next)
813 next = NEXT_INSN (insn);
814 if (INSN_P (insn) && noop_move_p (insn))
818 /* If we're about to remove the first insn of a libcall
819 then move the libcall note to the next real insn and
820 update the retval note. */
821 if ((note = find_reg_note (insn, REG_LIBCALL, NULL_RTX))
822 && XEXP (note, 0) != insn)
824 rtx new_libcall_insn = next_real_insn (insn);
825 rtx retval_note = find_reg_note (XEXP (note, 0),
826 REG_RETVAL, NULL_RTX);
827 REG_NOTES (new_libcall_insn)
828 = gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0),
829 REG_NOTES (new_libcall_insn));
830 XEXP (retval_note, 0) = new_libcall_insn;
833 /* Do not call delete_insn here since that may change
834 the basic block boundaries which upsets some callers. */
835 PUT_CODE (insn, NOTE);
836 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
837 NOTE_SOURCE_FILE (insn) = 0;
843 /* Delete any jump tables never referenced. We can't delete them at the
844 time of removing tablejump insn as they are referenced by the preceding
845 insns computing the destination, so we delay deleting and garbagecollect
846 them once life information is computed. */
848 delete_dead_jumptables ()
851 for (insn = get_insns (); insn; insn = next)
853 next = NEXT_INSN (insn);
854 if (GET_CODE (insn) == CODE_LABEL
855 && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
856 && GET_CODE (next) == JUMP_INSN
857 && (GET_CODE (PATTERN (next)) == ADDR_VEC
858 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
861 fprintf (rtl_dump_file, "Dead jumptable %i removed\n", INSN_UID (insn));
862 delete_insn (NEXT_INSN (insn));
864 next = NEXT_INSN (next);
869 /* Determine if the stack pointer is constant over the life of the function.
870 Only useful before prologues have been emitted. */
873 notice_stack_pointer_modification_1 (x, pat, data)
875 rtx pat ATTRIBUTE_UNUSED;
876 void *data ATTRIBUTE_UNUSED;
878 if (x == stack_pointer_rtx
879 /* The stack pointer is only modified indirectly as the result
880 of a push until later in flow. See the comments in rtl.texi
881 regarding Embedded Side-Effects on Addresses. */
882 || (GET_CODE (x) == MEM
883 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
884 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
885 current_function_sp_is_unchanging = 0;
889 notice_stack_pointer_modification (f)
894 /* Assume that the stack pointer is unchanging if alloca hasn't
896 current_function_sp_is_unchanging = !current_function_calls_alloca;
897 if (! current_function_sp_is_unchanging)
900 for (insn = f; insn; insn = NEXT_INSN (insn))
904 /* Check if insn modifies the stack pointer. */
905 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
907 if (! current_function_sp_is_unchanging)
913 /* Mark a register in SET. Hard registers in large modes get all
914 of their component registers set as well. */
921 regset set = (regset) xset;
922 int regno = REGNO (reg);
924 if (GET_MODE (reg) == BLKmode)
927 SET_REGNO_REG_SET (set, regno);
928 if (regno < FIRST_PSEUDO_REGISTER)
930 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
932 SET_REGNO_REG_SET (set, regno + n);
936 /* Mark those regs which are needed at the end of the function as live
937 at the end of the last basic block. */
940 mark_regs_live_at_end (set)
945 /* If exiting needs the right stack value, consider the stack pointer
946 live at the end of the function. */
947 if ((HAVE_epilogue && reload_completed)
948 || ! EXIT_IGNORE_STACK
949 || (! FRAME_POINTER_REQUIRED
950 && ! current_function_calls_alloca
951 && flag_omit_frame_pointer)
952 || current_function_sp_is_unchanging)
954 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
957 /* Mark the frame pointer if needed at the end of the function. If
958 we end up eliminating it, it will be removed from the live list
959 of each basic block by reload. */
961 if (! reload_completed || frame_pointer_needed)
963 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
964 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
965 /* If they are different, also mark the hard frame pointer as live. */
966 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
967 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
971 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
972 /* Many architectures have a GP register even without flag_pic.
973 Assume the pic register is not in use, or will be handled by
974 other means, if it is not fixed. */
975 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
976 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
977 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
980 /* Mark all global registers, and all registers used by the epilogue
981 as being live at the end of the function since they may be
982 referenced by our caller. */
983 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
984 if (global_regs[i] || EPILOGUE_USES (i))
985 SET_REGNO_REG_SET (set, i);
987 if (HAVE_epilogue && reload_completed)
989 /* Mark all call-saved registers that we actually used. */
990 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
991 if (regs_ever_live[i] && ! LOCAL_REGNO (i)
992 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
993 SET_REGNO_REG_SET (set, i);
996 #ifdef EH_RETURN_DATA_REGNO
997 /* Mark the registers that will contain data for the handler. */
998 if (reload_completed && current_function_calls_eh_return)
1001 unsigned regno = EH_RETURN_DATA_REGNO(i);
1002 if (regno == INVALID_REGNUM)
1004 SET_REGNO_REG_SET (set, regno);
1007 #ifdef EH_RETURN_STACKADJ_RTX
1008 if ((! HAVE_epilogue || ! reload_completed)
1009 && current_function_calls_eh_return)
1011 rtx tmp = EH_RETURN_STACKADJ_RTX;
1012 if (tmp && REG_P (tmp))
1013 mark_reg (tmp, set);
1016 #ifdef EH_RETURN_HANDLER_RTX
1017 if ((! HAVE_epilogue || ! reload_completed)
1018 && current_function_calls_eh_return)
1020 rtx tmp = EH_RETURN_HANDLER_RTX;
1021 if (tmp && REG_P (tmp))
1022 mark_reg (tmp, set);
1026 /* Mark function return value. */
1027 diddle_return_value (mark_reg, set);
1030 /* Callback function for for_each_successor_phi. DATA is a regset.
1031 Sets the SRC_REGNO, the regno of the phi alternative for phi node
1032 INSN, in the regset. */
1035 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
1036 rtx insn ATTRIBUTE_UNUSED;
1037 int dest_regno ATTRIBUTE_UNUSED;
1041 regset live = (regset) data;
1042 SET_REGNO_REG_SET (live, src_regno);
1046 /* Propagate global life info around the graph of basic blocks. Begin
1047 considering blocks with their corresponding bit set in BLOCKS_IN.
1048 If BLOCKS_IN is null, consider it the universal set.
1050 BLOCKS_OUT is set for every block that was changed. */
1053 calculate_global_regs_live (blocks_in, blocks_out, flags)
1054 sbitmap blocks_in, blocks_out;
1057 basic_block *queue, *qhead, *qtail, *qend;
1058 regset tmp, new_live_at_end, call_used;
1059 regset_head tmp_head, call_used_head;
1060 regset_head new_live_at_end_head;
1063 tmp = INITIALIZE_REG_SET (tmp_head);
1064 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
1065 call_used = INITIALIZE_REG_SET (call_used_head);
1067 /* Inconveniently, this is only readily available in hard reg set form. */
1068 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
1069 if (call_used_regs[i])
1070 SET_REGNO_REG_SET (call_used, i);
1072 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1073 because the `head == tail' style test for an empty queue doesn't
1074 work with a full queue. */
1075 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
1077 qhead = qend = queue + n_basic_blocks + 2;
1079 /* Queue the blocks set in the initial mask. Do this in reverse block
1080 number order so that we are more likely for the first round to do
1081 useful work. We use AUX non-null to flag that the block is queued. */
1084 /* Clear out the garbage that might be hanging out in bb->aux. */
1085 for (i = n_basic_blocks - 1; i >= 0; --i)
1086 BASIC_BLOCK (i)->aux = NULL;
1088 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
1090 basic_block bb = BASIC_BLOCK (i);
1097 for (i = 0; i < n_basic_blocks; ++i)
1099 basic_block bb = BASIC_BLOCK (i);
1106 sbitmap_zero (blocks_out);
1108 /* We work through the queue until there are no more blocks. What
1109 is live at the end of this block is precisely the union of what
1110 is live at the beginning of all its successors. So, we set its
1111 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1112 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1113 this block by walking through the instructions in this block in
1114 reverse order and updating as we go. If that changed
1115 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1116 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1118 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1119 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1120 must either be live at the end of the block, or used within the
1121 block. In the latter case, it will certainly never disappear
1122 from GLOBAL_LIVE_AT_START. In the former case, the register
1123 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1124 for one of the successor blocks. By induction, that cannot
1126 while (qhead != qtail)
1128 int rescan, changed;
1137 /* Begin by propagating live_at_start from the successor blocks. */
1138 CLEAR_REG_SET (new_live_at_end);
1139 for (e = bb->succ; e; e = e->succ_next)
1141 basic_block sb = e->dest;
1143 /* Call-clobbered registers die across exception and call edges. */
1144 /* ??? Abnormal call edges ignored for the moment, as this gets
1145 confused by sibling call edges, which crashes reg-stack. */
1146 if (e->flags & EDGE_EH)
1148 bitmap_operation (tmp, sb->global_live_at_start,
1149 call_used, BITMAP_AND_COMPL);
1150 IOR_REG_SET (new_live_at_end, tmp);
1153 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
1156 /* The all-important stack pointer must always be live. */
1157 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
1159 /* Before reload, there are a few registers that must be forced
1160 live everywhere -- which might not already be the case for
1161 blocks within infinite loops. */
1162 if (! reload_completed)
1164 /* Any reference to any pseudo before reload is a potential
1165 reference of the frame pointer. */
1166 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
1168 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1169 /* Pseudos with argument area equivalences may require
1170 reloading via the argument pointer. */
1171 if (fixed_regs[ARG_POINTER_REGNUM])
1172 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
1175 /* Any constant, or pseudo with constant equivalences, may
1176 require reloading from memory using the pic register. */
1177 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
1178 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
1179 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
1182 /* Regs used in phi nodes are not included in
1183 global_live_at_start, since they are live only along a
1184 particular edge. Set those regs that are live because of a
1185 phi node alternative corresponding to this particular block. */
1187 for_each_successor_phi (bb, &set_phi_alternative_reg,
1190 if (bb == ENTRY_BLOCK_PTR)
1192 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1196 /* On our first pass through this block, we'll go ahead and continue.
1197 Recognize first pass by local_set NULL. On subsequent passes, we
1198 get to skip out early if live_at_end wouldn't have changed. */
1200 if (bb->local_set == NULL)
1202 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1203 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1208 /* If any bits were removed from live_at_end, we'll have to
1209 rescan the block. This wouldn't be necessary if we had
1210 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1211 local_live is really dependent on live_at_end. */
1212 CLEAR_REG_SET (tmp);
1213 rescan = bitmap_operation (tmp, bb->global_live_at_end,
1214 new_live_at_end, BITMAP_AND_COMPL);
1218 /* If any of the registers in the new live_at_end set are
1219 conditionally set in this basic block, we must rescan.
1220 This is because conditional lifetimes at the end of the
1221 block do not just take the live_at_end set into account,
1222 but also the liveness at the start of each successor
1223 block. We can miss changes in those sets if we only
1224 compare the new live_at_end against the previous one. */
1225 CLEAR_REG_SET (tmp);
1226 rescan = bitmap_operation (tmp, new_live_at_end,
1227 bb->cond_local_set, BITMAP_AND);
1232 /* Find the set of changed bits. Take this opportunity
1233 to notice that this set is empty and early out. */
1234 CLEAR_REG_SET (tmp);
1235 changed = bitmap_operation (tmp, bb->global_live_at_end,
1236 new_live_at_end, BITMAP_XOR);
1240 /* If any of the changed bits overlap with local_set,
1241 we'll have to rescan the block. Detect overlap by
1242 the AND with ~local_set turning off bits. */
1243 rescan = bitmap_operation (tmp, tmp, bb->local_set,
1248 /* Let our caller know that BB changed enough to require its
1249 death notes updated. */
1251 SET_BIT (blocks_out, bb->index);
1255 /* Add to live_at_start the set of all registers in
1256 new_live_at_end that aren't in the old live_at_end. */
1258 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
1260 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1262 changed = bitmap_operation (bb->global_live_at_start,
1263 bb->global_live_at_start,
1270 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1272 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1273 into live_at_start. */
1274 propagate_block (bb, new_live_at_end, bb->local_set,
1275 bb->cond_local_set, flags);
1277 /* If live_at start didn't change, no need to go farther. */
1278 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
1281 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
1284 /* Queue all predecessors of BB so that we may re-examine
1285 their live_at_end. */
1286 for (e = bb->pred; e; e = e->pred_next)
1288 basic_block pb = e->src;
1289 if (pb->aux == NULL)
1300 FREE_REG_SET (new_live_at_end);
1301 FREE_REG_SET (call_used);
1305 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
1307 basic_block bb = BASIC_BLOCK (i);
1308 FREE_REG_SET (bb->local_set);
1309 FREE_REG_SET (bb->cond_local_set);
1314 for (i = n_basic_blocks - 1; i >= 0; --i)
1316 basic_block bb = BASIC_BLOCK (i);
1317 FREE_REG_SET (bb->local_set);
1318 FREE_REG_SET (bb->cond_local_set);
1326 /* This structure is used to pass parameters to an from the
1327 the function find_regno_partial(). It is used to pass in the
1328 register number we are looking, as well as to return any rtx
1332 unsigned regno_to_find;
1334 } find_regno_partial_param;
1337 /* Find the rtx for the reg numbers specified in 'data' if it is
1338 part of an expression which only uses part of the register. Return
1339 it in the structure passed in. */
1341 find_regno_partial (ptr, data)
1345 find_regno_partial_param *param = (find_regno_partial_param *)data;
1346 unsigned reg = param->regno_to_find;
1347 param->retval = NULL_RTX;
1349 if (*ptr == NULL_RTX)
1352 switch (GET_CODE (*ptr))
1356 case STRICT_LOW_PART:
1357 if (GET_CODE (XEXP (*ptr, 0)) == REG && REGNO (XEXP (*ptr, 0)) == reg)
1359 param->retval = XEXP (*ptr, 0);
1365 if (GET_CODE (SUBREG_REG (*ptr)) == REG
1366 && REGNO (SUBREG_REG (*ptr)) == reg)
1368 param->retval = SUBREG_REG (*ptr);
1380 /* Process all immediate successors of the entry block looking for pseudo
1381 registers which are live on entry. Find all of those whose first
1382 instance is a partial register reference of some kind, and initialize
1383 them to 0 after the entry block. This will prevent bit sets within
1384 registers whose value is unknown, and may contain some kind of sticky
1385 bits we don't want. */
1388 initialize_uninitialized_subregs ()
1392 int reg, did_something = 0;
1393 find_regno_partial_param param;
1395 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
1397 basic_block bb = e->dest;
1398 regset map = bb->global_live_at_start;
1399 EXECUTE_IF_SET_IN_REG_SET (map,
1400 FIRST_PSEUDO_REGISTER, reg,
1402 int uid = REGNO_FIRST_UID (reg);
1405 /* Find an insn which mentions the register we are looking for.
1406 Its preferable to have an instance of the register's rtl since
1407 there may be various flags set which we need to duplicate.
1408 If we can't find it, its probably an automatic whose initial
1409 value doesn't matter, or hopefully something we don't care about. */
1410 for (i = get_insns (); i && INSN_UID (i) != uid; i = NEXT_INSN (i))
1414 /* Found the insn, now get the REG rtx, if we can. */
1415 param.regno_to_find = reg;
1416 for_each_rtx (&i, find_regno_partial, ¶m);
1417 if (param.retval != NULL_RTX)
1419 insn = gen_move_insn (param.retval,
1420 CONST0_RTX (GET_MODE (param.retval)));
1421 insert_insn_on_edge (insn, e);
1429 commit_edge_insertions ();
1430 return did_something;
1434 /* Subroutines of life analysis. */
1436 /* Allocate the permanent data structures that represent the results
1437 of life analysis. Not static since used also for stupid life analysis. */
1440 allocate_bb_life_data ()
1444 for (i = 0; i < n_basic_blocks; i++)
1446 basic_block bb = BASIC_BLOCK (i);
1448 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1449 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1452 ENTRY_BLOCK_PTR->global_live_at_end
1453 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1454 EXIT_BLOCK_PTR->global_live_at_start
1455 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1457 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1461 allocate_reg_life_data ()
1465 max_regno = max_reg_num ();
1467 /* Recalculate the register space, in case it has grown. Old style
1468 vector oriented regsets would set regset_{size,bytes} here also. */
1469 allocate_reg_info (max_regno, FALSE, FALSE);
1471 /* Reset all the data we'll collect in propagate_block and its
1473 for (i = 0; i < max_regno; i++)
1477 REG_N_DEATHS (i) = 0;
1478 REG_N_CALLS_CROSSED (i) = 0;
1479 REG_LIVE_LENGTH (i) = 0;
1480 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
1484 /* Delete dead instructions for propagate_block. */
1487 propagate_block_delete_insn (bb, insn)
1491 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
1494 /* If the insn referred to a label, and that label was attached to
1495 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1496 pretty much mandatory to delete it, because the ADDR_VEC may be
1497 referencing labels that no longer exist.
1499 INSN may reference a deleted label, particularly when a jump
1500 table has been optimized into a direct jump. There's no
1501 real good way to fix up the reference to the deleted label
1502 when the label is deleted, so we just allow it here.
1504 After dead code elimination is complete, we do search for
1505 any REG_LABEL notes which reference deleted labels as a
1508 if (inote && GET_CODE (inote) == CODE_LABEL)
1510 rtx label = XEXP (inote, 0);
1513 /* The label may be forced if it has been put in the constant
1514 pool. If that is the only use we must discard the table
1515 jump following it, but not the label itself. */
1516 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
1517 && (next = next_nonnote_insn (label)) != NULL
1518 && GET_CODE (next) == JUMP_INSN
1519 && (GET_CODE (PATTERN (next)) == ADDR_VEC
1520 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
1522 rtx pat = PATTERN (next);
1523 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
1524 int len = XVECLEN (pat, diff_vec_p);
1527 for (i = 0; i < len; i++)
1528 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
1534 if (bb->end == insn)
1538 purge_dead_edges (bb);
1541 /* Delete dead libcalls for propagate_block. Return the insn
1542 before the libcall. */
1545 propagate_block_delete_libcall ( insn, note)
1548 rtx first = XEXP (note, 0);
1549 rtx before = PREV_INSN (first);
1551 delete_insn_chain (first, insn);
1555 /* Update the life-status of regs for one insn. Return the previous insn. */
1558 propagate_one_insn (pbi, insn)
1559 struct propagate_block_info *pbi;
1562 rtx prev = PREV_INSN (insn);
1563 int flags = pbi->flags;
1564 int insn_is_dead = 0;
1565 int libcall_is_dead = 0;
1569 if (! INSN_P (insn))
1572 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1573 if (flags & PROP_SCAN_DEAD_CODE)
1575 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
1576 libcall_is_dead = (insn_is_dead && note != 0
1577 && libcall_dead_p (pbi, note, insn));
1580 /* If an instruction consists of just dead store(s) on final pass,
1582 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
1584 /* If we're trying to delete a prologue or epilogue instruction
1585 that isn't flagged as possibly being dead, something is wrong.
1586 But if we are keeping the stack pointer depressed, we might well
1587 be deleting insns that are used to compute the amount to update
1588 it by, so they are fine. */
1589 if (reload_completed
1590 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1591 && (TYPE_RETURNS_STACK_DEPRESSED
1592 (TREE_TYPE (current_function_decl))))
1593 && (((HAVE_epilogue || HAVE_prologue)
1594 && prologue_epilogue_contains (insn))
1595 || (HAVE_sibcall_epilogue
1596 && sibcall_epilogue_contains (insn)))
1597 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
1598 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn);
1600 /* Record sets. Do this even for dead instructions, since they
1601 would have killed the values if they hadn't been deleted. */
1602 mark_set_regs (pbi, PATTERN (insn), insn);
1604 /* CC0 is now known to be dead. Either this insn used it,
1605 in which case it doesn't anymore, or clobbered it,
1606 so the next insn can't use it. */
1609 if (libcall_is_dead)
1610 prev = propagate_block_delete_libcall ( insn, note);
1612 propagate_block_delete_insn (pbi->bb, insn);
1617 /* See if this is an increment or decrement that can be merged into
1618 a following memory address. */
1621 rtx x = single_set (insn);
1623 /* Does this instruction increment or decrement a register? */
1624 if ((flags & PROP_AUTOINC)
1626 && GET_CODE (SET_DEST (x)) == REG
1627 && (GET_CODE (SET_SRC (x)) == PLUS
1628 || GET_CODE (SET_SRC (x)) == MINUS)
1629 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1630 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1631 /* Ok, look for a following memory ref we can combine with.
1632 If one is found, change the memory ref to a PRE_INC
1633 or PRE_DEC, cancel this insn, and return 1.
1634 Return 0 if nothing has been done. */
1635 && try_pre_increment_1 (pbi, insn))
1638 #endif /* AUTO_INC_DEC */
1640 CLEAR_REG_SET (pbi->new_set);
1642 /* If this is not the final pass, and this insn is copying the value of
1643 a library call and it's dead, don't scan the insns that perform the
1644 library call, so that the call's arguments are not marked live. */
1645 if (libcall_is_dead)
1647 /* Record the death of the dest reg. */
1648 mark_set_regs (pbi, PATTERN (insn), insn);
1650 insn = XEXP (note, 0);
1651 return PREV_INSN (insn);
1653 else if (GET_CODE (PATTERN (insn)) == SET
1654 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1655 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1656 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1657 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1658 /* We have an insn to pop a constant amount off the stack.
1659 (Such insns use PLUS regardless of the direction of the stack,
1660 and any insn to adjust the stack by a constant is always a pop.)
1661 These insns, if not dead stores, have no effect on life. */
1666 /* Any regs live at the time of a call instruction must not go
1667 in a register clobbered by calls. Find all regs now live and
1668 record this for them. */
1670 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
1671 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
1672 { REG_N_CALLS_CROSSED (i)++; });
1674 /* Record sets. Do this even for dead instructions, since they
1675 would have killed the values if they hadn't been deleted. */
1676 mark_set_regs (pbi, PATTERN (insn), insn);
1678 if (GET_CODE (insn) == CALL_INSN)
1684 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1685 cond = COND_EXEC_TEST (PATTERN (insn));
1687 /* Non-constant calls clobber memory. */
1688 if (! CONST_OR_PURE_CALL_P (insn))
1690 free_EXPR_LIST_list (&pbi->mem_set_list);
1691 pbi->mem_set_list_len = 0;
1694 /* There may be extra registers to be clobbered. */
1695 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1697 note = XEXP (note, 1))
1698 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
1699 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
1700 cond, insn, pbi->flags);
1702 /* Calls change all call-used and global registers. */
1703 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1704 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1706 /* We do not want REG_UNUSED notes for these registers. */
1707 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
1709 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
1713 /* If an insn doesn't use CC0, it becomes dead since we assume
1714 that every insn clobbers it. So show it dead here;
1715 mark_used_regs will set it live if it is referenced. */
1720 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
1721 if ((flags & PROP_EQUAL_NOTES)
1722 && ((note = find_reg_note (insn, REG_EQUAL, NULL_RTX))
1723 || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX))))
1724 mark_used_regs (pbi, XEXP (note, 0), NULL_RTX, insn);
1726 /* Sometimes we may have inserted something before INSN (such as a move)
1727 when we make an auto-inc. So ensure we will scan those insns. */
1729 prev = PREV_INSN (insn);
1732 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1738 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1739 cond = COND_EXEC_TEST (PATTERN (insn));
1741 /* Calls use their arguments. */
1742 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1744 note = XEXP (note, 1))
1745 if (GET_CODE (XEXP (note, 0)) == USE)
1746 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
1749 /* The stack ptr is used (honorarily) by a CALL insn. */
1750 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
1752 /* Calls may also reference any of the global registers,
1753 so they are made live. */
1754 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1756 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
1761 /* On final pass, update counts of how many insns in which each reg
1763 if (flags & PROP_REG_INFO)
1764 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
1765 { REG_LIVE_LENGTH (i)++; });
1770 /* Initialize a propagate_block_info struct for public consumption.
1771 Note that the structure itself is opaque to this file, but that
1772 the user can use the regsets provided here. */
1774 struct propagate_block_info *
1775 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
1777 regset live, local_set, cond_local_set;
1780 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
1783 pbi->reg_live = live;
1784 pbi->mem_set_list = NULL_RTX;
1785 pbi->mem_set_list_len = 0;
1786 pbi->local_set = local_set;
1787 pbi->cond_local_set = cond_local_set;
1791 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
1792 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
1794 pbi->reg_next_use = NULL;
1796 pbi->new_set = BITMAP_XMALLOC ();
1798 #ifdef HAVE_conditional_execution
1799 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
1800 free_reg_cond_life_info);
1801 pbi->reg_cond_reg = BITMAP_XMALLOC ();
1803 /* If this block ends in a conditional branch, for each register live
1804 from one side of the branch and not the other, record the register
1805 as conditionally dead. */
1806 if (GET_CODE (bb->end) == JUMP_INSN
1807 && any_condjump_p (bb->end))
1809 regset_head diff_head;
1810 regset diff = INITIALIZE_REG_SET (diff_head);
1811 basic_block bb_true, bb_false;
1812 rtx cond_true, cond_false, set_src;
1815 /* Identify the successor blocks. */
1816 bb_true = bb->succ->dest;
1817 if (bb->succ->succ_next != NULL)
1819 bb_false = bb->succ->succ_next->dest;
1821 if (bb->succ->flags & EDGE_FALLTHRU)
1823 basic_block t = bb_false;
1827 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
1832 /* This can happen with a conditional jump to the next insn. */
1833 if (JUMP_LABEL (bb->end) != bb_true->head)
1836 /* Simplest way to do nothing. */
1840 /* Extract the condition from the branch. */
1841 set_src = SET_SRC (pc_set (bb->end));
1842 cond_true = XEXP (set_src, 0);
1843 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
1844 GET_MODE (cond_true), XEXP (cond_true, 0),
1845 XEXP (cond_true, 1));
1846 if (GET_CODE (XEXP (set_src, 1)) == PC)
1849 cond_false = cond_true;
1853 /* Compute which register lead different lives in the successors. */
1854 if (bitmap_operation (diff, bb_true->global_live_at_start,
1855 bb_false->global_live_at_start, BITMAP_XOR))
1857 rtx reg = XEXP (cond_true, 0);
1859 if (GET_CODE (reg) == SUBREG)
1860 reg = SUBREG_REG (reg);
1862 if (GET_CODE (reg) != REG)
1865 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
1867 /* For each such register, mark it conditionally dead. */
1868 EXECUTE_IF_SET_IN_REG_SET
1871 struct reg_cond_life_info *rcli;
1874 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
1876 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
1880 rcli->condition = cond;
1881 rcli->stores = const0_rtx;
1882 rcli->orig_condition = cond;
1884 splay_tree_insert (pbi->reg_cond_dead, i,
1885 (splay_tree_value) rcli);
1889 FREE_REG_SET (diff);
1893 /* If this block has no successors, any stores to the frame that aren't
1894 used later in the block are dead. So make a pass over the block
1895 recording any such that are made and show them dead at the end. We do
1896 a very conservative and simple job here. */
1898 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1899 && (TYPE_RETURNS_STACK_DEPRESSED
1900 (TREE_TYPE (current_function_decl))))
1901 && (flags & PROP_SCAN_DEAD_CODE)
1902 && (bb->succ == NULL
1903 || (bb->succ->succ_next == NULL
1904 && bb->succ->dest == EXIT_BLOCK_PTR
1905 && ! current_function_calls_eh_return)))
1908 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
1909 if (GET_CODE (insn) == INSN
1910 && (set = single_set (insn))
1911 && GET_CODE (SET_DEST (set)) == MEM)
1913 rtx mem = SET_DEST (set);
1914 rtx canon_mem = canon_rtx (mem);
1916 /* This optimization is performed by faking a store to the
1917 memory at the end of the block. This doesn't work for
1918 unchanging memories because multiple stores to unchanging
1919 memory is illegal and alias analysis doesn't consider it. */
1920 if (RTX_UNCHANGING_P (canon_mem))
1923 if (XEXP (canon_mem, 0) == frame_pointer_rtx
1924 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
1925 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
1926 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
1927 add_to_mem_set_list (pbi, canon_mem);
1934 /* Release a propagate_block_info struct. */
1937 free_propagate_block_info (pbi)
1938 struct propagate_block_info *pbi;
1940 free_EXPR_LIST_list (&pbi->mem_set_list);
1942 BITMAP_XFREE (pbi->new_set);
1944 #ifdef HAVE_conditional_execution
1945 splay_tree_delete (pbi->reg_cond_dead);
1946 BITMAP_XFREE (pbi->reg_cond_reg);
1949 if (pbi->reg_next_use)
1950 free (pbi->reg_next_use);
1955 /* Compute the registers live at the beginning of a basic block BB from
1956 those live at the end.
1958 When called, REG_LIVE contains those live at the end. On return, it
1959 contains those live at the beginning.
1961 LOCAL_SET, if non-null, will be set with all registers killed
1962 unconditionally by this basic block.
1963 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
1964 killed conditionally by this basic block. If there is any unconditional
1965 set of a register, then the corresponding bit will be set in LOCAL_SET
1966 and cleared in COND_LOCAL_SET.
1967 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
1968 case, the resulting set will be equal to the union of the two sets that
1969 would otherwise be computed.
1971 Return non-zero if an INSN is deleted (i.e. by dead code removal). */
1974 propagate_block (bb, live, local_set, cond_local_set, flags)
1978 regset cond_local_set;
1981 struct propagate_block_info *pbi;
1985 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
1987 if (flags & PROP_REG_INFO)
1991 /* Process the regs live at the end of the block.
1992 Mark them as not local to any one basic block. */
1993 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
1994 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
1997 /* Scan the block an insn at a time from end to beginning. */
2000 for (insn = bb->end;; insn = prev)
2002 /* If this is a call to `setjmp' et al, warn if any
2003 non-volatile datum is live. */
2004 if ((flags & PROP_REG_INFO)
2005 && GET_CODE (insn) == CALL_INSN
2006 && find_reg_note (insn, REG_SETJMP, NULL))
2007 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
2009 prev = propagate_one_insn (pbi, insn);
2010 changed |= NEXT_INSN (prev) != insn;
2012 if (insn == bb->head)
2016 free_propagate_block_info (pbi);
2021 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2022 (SET expressions whose destinations are registers dead after the insn).
2023 NEEDED is the regset that says which regs are alive after the insn.
2025 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
2027 If X is the entire body of an insn, NOTES contains the reg notes
2028 pertaining to the insn. */
2031 insn_dead_p (pbi, x, call_ok, notes)
2032 struct propagate_block_info *pbi;
2035 rtx notes ATTRIBUTE_UNUSED;
2037 enum rtx_code code = GET_CODE (x);
2040 /* As flow is invoked after combine, we must take existing AUTO_INC
2041 expressions into account. */
2042 for (; notes; notes = XEXP (notes, 1))
2044 if (REG_NOTE_KIND (notes) == REG_INC)
2046 int regno = REGNO (XEXP (notes, 0));
2048 /* Don't delete insns to set global regs. */
2049 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2050 || REGNO_REG_SET_P (pbi->reg_live, regno))
2056 /* If setting something that's a reg or part of one,
2057 see if that register's altered value will be live. */
2061 rtx r = SET_DEST (x);
2064 if (GET_CODE (r) == CC0)
2065 return ! pbi->cc0_live;
2068 /* A SET that is a subroutine call cannot be dead. */
2069 if (GET_CODE (SET_SRC (x)) == CALL)
2075 /* Don't eliminate loads from volatile memory or volatile asms. */
2076 else if (volatile_refs_p (SET_SRC (x)))
2079 if (GET_CODE (r) == MEM)
2083 if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode)
2086 canon_r = canon_rtx (r);
2088 /* Walk the set of memory locations we are currently tracking
2089 and see if one is an identical match to this memory location.
2090 If so, this memory write is dead (remember, we're walking
2091 backwards from the end of the block to the start). Since
2092 rtx_equal_p does not check the alias set or flags, we also
2093 must have the potential for them to conflict (anti_dependence). */
2094 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
2095 if (anti_dependence (r, XEXP (temp, 0)))
2097 rtx mem = XEXP (temp, 0);
2099 if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0))
2100 && (GET_MODE_SIZE (GET_MODE (canon_r))
2101 <= GET_MODE_SIZE (GET_MODE (mem))))
2105 /* Check if memory reference matches an auto increment. Only
2106 post increment/decrement or modify are valid. */
2107 if (GET_MODE (mem) == GET_MODE (r)
2108 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
2109 || GET_CODE (XEXP (mem, 0)) == POST_INC
2110 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
2111 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
2112 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
2119 while (GET_CODE (r) == SUBREG
2120 || GET_CODE (r) == STRICT_LOW_PART
2121 || GET_CODE (r) == ZERO_EXTRACT)
2124 if (GET_CODE (r) == REG)
2126 int regno = REGNO (r);
2129 if (REGNO_REG_SET_P (pbi->reg_live, regno))
2132 /* If this is a hard register, verify that subsequent
2133 words are not needed. */
2134 if (regno < FIRST_PSEUDO_REGISTER)
2136 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
2139 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
2143 /* Don't delete insns to set global regs. */
2144 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2147 /* Make sure insns to set the stack pointer aren't deleted. */
2148 if (regno == STACK_POINTER_REGNUM)
2151 /* ??? These bits might be redundant with the force live bits
2152 in calculate_global_regs_live. We would delete from
2153 sequential sets; whether this actually affects real code
2154 for anything but the stack pointer I don't know. */
2155 /* Make sure insns to set the frame pointer aren't deleted. */
2156 if (regno == FRAME_POINTER_REGNUM
2157 && (! reload_completed || frame_pointer_needed))
2159 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2160 if (regno == HARD_FRAME_POINTER_REGNUM
2161 && (! reload_completed || frame_pointer_needed))
2165 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2166 /* Make sure insns to set arg pointer are never deleted
2167 (if the arg pointer isn't fixed, there will be a USE
2168 for it, so we can treat it normally). */
2169 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2173 /* Otherwise, the set is dead. */
2179 /* If performing several activities, insn is dead if each activity
2180 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2181 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2183 else if (code == PARALLEL)
2185 int i = XVECLEN (x, 0);
2187 for (i--; i >= 0; i--)
2188 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
2189 && GET_CODE (XVECEXP (x, 0, i)) != USE
2190 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
2196 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2197 is not necessarily true for hard registers. */
2198 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
2199 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
2200 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
2203 /* We do not check other CLOBBER or USE here. An insn consisting of just
2204 a CLOBBER or just a USE should not be deleted. */
2208 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2209 return 1 if the entire library call is dead.
2210 This is true if INSN copies a register (hard or pseudo)
2211 and if the hard return reg of the call insn is dead.
2212 (The caller should have tested the destination of the SET inside
2213 INSN already for death.)
2215 If this insn doesn't just copy a register, then we don't
2216 have an ordinary libcall. In that case, cse could not have
2217 managed to substitute the source for the dest later on,
2218 so we can assume the libcall is dead.
2220 PBI is the block info giving pseudoregs live before this insn.
2221 NOTE is the REG_RETVAL note of the insn. */
2224 libcall_dead_p (pbi, note, insn)
2225 struct propagate_block_info *pbi;
2229 rtx x = single_set (insn);
2233 rtx r = SET_SRC (x);
2235 if (GET_CODE (r) == REG)
2237 rtx call = XEXP (note, 0);
2241 /* Find the call insn. */
2242 while (call != insn && GET_CODE (call) != CALL_INSN)
2243 call = NEXT_INSN (call);
2245 /* If there is none, do nothing special,
2246 since ordinary death handling can understand these insns. */
2250 /* See if the hard reg holding the value is dead.
2251 If this is a PARALLEL, find the call within it. */
2252 call_pat = PATTERN (call);
2253 if (GET_CODE (call_pat) == PARALLEL)
2255 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
2256 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
2257 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
2260 /* This may be a library call that is returning a value
2261 via invisible pointer. Do nothing special, since
2262 ordinary death handling can understand these insns. */
2266 call_pat = XVECEXP (call_pat, 0, i);
2269 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
2275 /* Return 1 if register REGNO was used before it was set, i.e. if it is
2276 live at function entry. Don't count global register variables, variables
2277 in registers that can be used for function arg passing, or variables in
2278 fixed hard registers. */
2281 regno_uninitialized (regno)
2284 if (n_basic_blocks == 0
2285 || (regno < FIRST_PSEUDO_REGISTER
2286 && (global_regs[regno]
2287 || fixed_regs[regno]
2288 || FUNCTION_ARG_REGNO_P (regno))))
2291 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
2294 /* 1 if register REGNO was alive at a place where `setjmp' was called
2295 and was set more than once or is an argument.
2296 Such regs may be clobbered by `longjmp'. */
2299 regno_clobbered_at_setjmp (regno)
2302 if (n_basic_blocks == 0)
2305 return ((REG_N_SETS (regno) > 1
2306 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
2307 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
2310 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2311 maximal list size; look for overlaps in mode and select the largest. */
2313 add_to_mem_set_list (pbi, mem)
2314 struct propagate_block_info *pbi;
2319 /* We don't know how large a BLKmode store is, so we must not
2320 take them into consideration. */
2321 if (GET_MODE (mem) == BLKmode)
2324 for (i = pbi->mem_set_list; i ; i = XEXP (i, 1))
2326 rtx e = XEXP (i, 0);
2327 if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0)))
2329 if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e)))
2332 /* If we must store a copy of the mem, we can just modify
2333 the mode of the stored copy. */
2334 if (pbi->flags & PROP_AUTOINC)
2335 PUT_MODE (e, GET_MODE (mem));
2344 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN)
2347 /* Store a copy of mem, otherwise the address may be
2348 scrogged by find_auto_inc. */
2349 if (pbi->flags & PROP_AUTOINC)
2350 mem = shallow_copy_rtx (mem);
2352 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
2353 pbi->mem_set_list_len++;
2357 /* INSN references memory, possibly using autoincrement addressing modes.
2358 Find any entries on the mem_set_list that need to be invalidated due
2359 to an address change. */
2362 invalidate_mems_from_autoinc (pbi, insn)
2363 struct propagate_block_info *pbi;
2366 rtx note = REG_NOTES (insn);
2367 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
2368 if (REG_NOTE_KIND (note) == REG_INC)
2369 invalidate_mems_from_set (pbi, XEXP (note, 0));
2372 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2375 invalidate_mems_from_set (pbi, exp)
2376 struct propagate_block_info *pbi;
2379 rtx temp = pbi->mem_set_list;
2380 rtx prev = NULL_RTX;
2385 next = XEXP (temp, 1);
2386 if (reg_overlap_mentioned_p (exp, XEXP (temp, 0)))
2388 /* Splice this entry out of the list. */
2390 XEXP (prev, 1) = next;
2392 pbi->mem_set_list = next;
2393 free_EXPR_LIST_node (temp);
2394 pbi->mem_set_list_len--;
2402 /* Process the registers that are set within X. Their bits are set to
2403 1 in the regset DEAD, because they are dead prior to this insn.
2405 If INSN is nonzero, it is the insn being processed.
2407 FLAGS is the set of operations to perform. */
2410 mark_set_regs (pbi, x, insn)
2411 struct propagate_block_info *pbi;
2414 rtx cond = NULL_RTX;
2419 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2421 if (REG_NOTE_KIND (link) == REG_INC)
2422 mark_set_1 (pbi, SET, XEXP (link, 0),
2423 (GET_CODE (x) == COND_EXEC
2424 ? COND_EXEC_TEST (x) : NULL_RTX),
2428 switch (code = GET_CODE (x))
2432 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
2436 cond = COND_EXEC_TEST (x);
2437 x = COND_EXEC_CODE (x);
2444 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2446 rtx sub = XVECEXP (x, 0, i);
2447 switch (code = GET_CODE (sub))
2450 if (cond != NULL_RTX)
2453 cond = COND_EXEC_TEST (sub);
2454 sub = COND_EXEC_CODE (sub);
2455 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
2461 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
2476 /* Process a single set, which appears in INSN. REG (which may not
2477 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2478 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2479 If the set is conditional (because it appear in a COND_EXEC), COND
2480 will be the condition. */
2483 mark_set_1 (pbi, code, reg, cond, insn, flags)
2484 struct propagate_block_info *pbi;
2486 rtx reg, cond, insn;
2489 int regno_first = -1, regno_last = -1;
2490 unsigned long not_dead = 0;
2493 /* Modifying just one hardware register of a multi-reg value or just a
2494 byte field of a register does not mean the value from before this insn
2495 is now dead. Of course, if it was dead after it's unused now. */
2497 switch (GET_CODE (reg))
2500 /* Some targets place small structures in registers for return values of
2501 functions. We have to detect this case specially here to get correct
2502 flow information. */
2503 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
2504 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
2505 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
2511 case STRICT_LOW_PART:
2512 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2514 reg = XEXP (reg, 0);
2515 while (GET_CODE (reg) == SUBREG
2516 || GET_CODE (reg) == ZERO_EXTRACT
2517 || GET_CODE (reg) == SIGN_EXTRACT
2518 || GET_CODE (reg) == STRICT_LOW_PART);
2519 if (GET_CODE (reg) == MEM)
2521 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
2525 regno_last = regno_first = REGNO (reg);
2526 if (regno_first < FIRST_PSEUDO_REGISTER)
2527 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
2531 if (GET_CODE (SUBREG_REG (reg)) == REG)
2533 enum machine_mode outer_mode = GET_MODE (reg);
2534 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
2536 /* Identify the range of registers affected. This is moderately
2537 tricky for hard registers. See alter_subreg. */
2539 regno_last = regno_first = REGNO (SUBREG_REG (reg));
2540 if (regno_first < FIRST_PSEUDO_REGISTER)
2542 regno_first += subreg_regno_offset (regno_first, inner_mode,
2545 regno_last = (regno_first
2546 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
2548 /* Since we've just adjusted the register number ranges, make
2549 sure REG matches. Otherwise some_was_live will be clear
2550 when it shouldn't have been, and we'll create incorrect
2551 REG_UNUSED notes. */
2552 reg = gen_rtx_REG (outer_mode, regno_first);
2556 /* If the number of words in the subreg is less than the number
2557 of words in the full register, we have a well-defined partial
2558 set. Otherwise the high bits are undefined.
2560 This is only really applicable to pseudos, since we just took
2561 care of multi-word hard registers. */
2562 if (((GET_MODE_SIZE (outer_mode)
2563 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
2564 < ((GET_MODE_SIZE (inner_mode)
2565 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
2566 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
2569 reg = SUBREG_REG (reg);
2573 reg = SUBREG_REG (reg);
2580 /* If this set is a MEM, then it kills any aliased writes.
2581 If this set is a REG, then it kills any MEMs which use the reg. */
2582 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2584 if (GET_CODE (reg) == REG)
2585 invalidate_mems_from_set (pbi, reg);
2587 /* If the memory reference had embedded side effects (autoincrement
2588 address modes. Then we may need to kill some entries on the
2590 if (insn && GET_CODE (reg) == MEM)
2591 invalidate_mems_from_autoinc (pbi, insn);
2593 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
2594 /* ??? With more effort we could track conditional memory life. */
2596 /* There are no REG_INC notes for SP, so we can't assume we'll see
2597 everything that invalidates it. To be safe, don't eliminate any
2598 stores though SP; none of them should be redundant anyway. */
2599 && ! reg_mentioned_p (stack_pointer_rtx, reg))
2600 add_to_mem_set_list (pbi, canon_rtx (reg));
2603 if (GET_CODE (reg) == REG
2604 && ! (regno_first == FRAME_POINTER_REGNUM
2605 && (! reload_completed || frame_pointer_needed))
2606 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2607 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
2608 && (! reload_completed || frame_pointer_needed))
2610 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2611 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
2615 int some_was_live = 0, some_was_dead = 0;
2617 for (i = regno_first; i <= regno_last; ++i)
2619 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
2622 /* Order of the set operation matters here since both
2623 sets may be the same. */
2624 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
2625 if (cond != NULL_RTX
2626 && ! REGNO_REG_SET_P (pbi->local_set, i))
2627 SET_REGNO_REG_SET (pbi->cond_local_set, i);
2629 SET_REGNO_REG_SET (pbi->local_set, i);
2631 if (code != CLOBBER)
2632 SET_REGNO_REG_SET (pbi->new_set, i);
2634 some_was_live |= needed_regno;
2635 some_was_dead |= ! needed_regno;
2638 #ifdef HAVE_conditional_execution
2639 /* Consider conditional death in deciding that the register needs
2641 if (some_was_live && ! not_dead
2642 /* The stack pointer is never dead. Well, not strictly true,
2643 but it's very difficult to tell from here. Hopefully
2644 combine_stack_adjustments will fix up the most egregious
2646 && regno_first != STACK_POINTER_REGNUM)
2648 for (i = regno_first; i <= regno_last; ++i)
2649 if (! mark_regno_cond_dead (pbi, i, cond))
2650 not_dead |= ((unsigned long) 1) << (i - regno_first);
2654 /* Additional data to record if this is the final pass. */
2655 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
2656 | PROP_DEATH_NOTES | PROP_AUTOINC))
2659 int blocknum = pbi->bb->index;
2662 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2664 y = pbi->reg_next_use[regno_first];
2666 /* The next use is no longer next, since a store intervenes. */
2667 for (i = regno_first; i <= regno_last; ++i)
2668 pbi->reg_next_use[i] = 0;
2671 if (flags & PROP_REG_INFO)
2673 for (i = regno_first; i <= regno_last; ++i)
2675 /* Count (weighted) references, stores, etc. This counts a
2676 register twice if it is modified, but that is correct. */
2677 REG_N_SETS (i) += 1;
2678 REG_N_REFS (i) += 1;
2679 REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb);
2681 /* The insns where a reg is live are normally counted
2682 elsewhere, but we want the count to include the insn
2683 where the reg is set, and the normal counting mechanism
2684 would not count it. */
2685 REG_LIVE_LENGTH (i) += 1;
2688 /* If this is a hard reg, record this function uses the reg. */
2689 if (regno_first < FIRST_PSEUDO_REGISTER)
2691 for (i = regno_first; i <= regno_last; i++)
2692 regs_ever_live[i] = 1;
2696 /* Keep track of which basic blocks each reg appears in. */
2697 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
2698 REG_BASIC_BLOCK (regno_first) = blocknum;
2699 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
2700 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
2704 if (! some_was_dead)
2706 if (flags & PROP_LOG_LINKS)
2708 /* Make a logical link from the next following insn
2709 that uses this register, back to this insn.
2710 The following insns have already been processed.
2712 We don't build a LOG_LINK for hard registers containing
2713 in ASM_OPERANDs. If these registers get replaced,
2714 we might wind up changing the semantics of the insn,
2715 even if reload can make what appear to be valid
2716 assignments later. */
2717 if (y && (BLOCK_NUM (y) == blocknum)
2718 && (regno_first >= FIRST_PSEUDO_REGISTER
2719 || asm_noperands (PATTERN (y)) < 0))
2720 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
2725 else if (! some_was_live)
2727 if (flags & PROP_REG_INFO)
2728 REG_N_DEATHS (regno_first) += 1;
2730 if (flags & PROP_DEATH_NOTES)
2732 /* Note that dead stores have already been deleted
2733 when possible. If we get here, we have found a
2734 dead store that cannot be eliminated (because the
2735 same insn does something useful). Indicate this
2736 by marking the reg being set as dying here. */
2738 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2743 if (flags & PROP_DEATH_NOTES)
2745 /* This is a case where we have a multi-word hard register
2746 and some, but not all, of the words of the register are
2747 needed in subsequent insns. Write REG_UNUSED notes
2748 for those parts that were not needed. This case should
2751 for (i = regno_first; i <= regno_last; ++i)
2752 if (! REGNO_REG_SET_P (pbi->reg_live, i))
2754 = alloc_EXPR_LIST (REG_UNUSED,
2755 gen_rtx_REG (reg_raw_mode[i], i),
2761 /* Mark the register as being dead. */
2763 /* The stack pointer is never dead. Well, not strictly true,
2764 but it's very difficult to tell from here. Hopefully
2765 combine_stack_adjustments will fix up the most egregious
2767 && regno_first != STACK_POINTER_REGNUM)
2769 for (i = regno_first; i <= regno_last; ++i)
2770 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
2771 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
2774 else if (GET_CODE (reg) == REG)
2776 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2777 pbi->reg_next_use[regno_first] = 0;
2780 /* If this is the last pass and this is a SCRATCH, show it will be dying
2781 here and count it. */
2782 else if (GET_CODE (reg) == SCRATCH)
2784 if (flags & PROP_DEATH_NOTES)
2786 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2790 #ifdef HAVE_conditional_execution
2791 /* Mark REGNO conditionally dead.
2792 Return true if the register is now unconditionally dead. */
2795 mark_regno_cond_dead (pbi, regno, cond)
2796 struct propagate_block_info *pbi;
2800 /* If this is a store to a predicate register, the value of the
2801 predicate is changing, we don't know that the predicate as seen
2802 before is the same as that seen after. Flush all dependent
2803 conditions from reg_cond_dead. This will make all such
2804 conditionally live registers unconditionally live. */
2805 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
2806 flush_reg_cond_reg (pbi, regno);
2808 /* If this is an unconditional store, remove any conditional
2809 life that may have existed. */
2810 if (cond == NULL_RTX)
2811 splay_tree_remove (pbi->reg_cond_dead, regno);
2814 splay_tree_node node;
2815 struct reg_cond_life_info *rcli;
2818 /* Otherwise this is a conditional set. Record that fact.
2819 It may have been conditionally used, or there may be a
2820 subsequent set with a complimentary condition. */
2822 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
2825 /* The register was unconditionally live previously.
2826 Record the current condition as the condition under
2827 which it is dead. */
2828 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
2829 rcli->condition = cond;
2830 rcli->stores = cond;
2831 rcli->orig_condition = const0_rtx;
2832 splay_tree_insert (pbi->reg_cond_dead, regno,
2833 (splay_tree_value) rcli);
2835 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2837 /* Not unconditionally dead. */
2842 /* The register was conditionally live previously.
2843 Add the new condition to the old. */
2844 rcli = (struct reg_cond_life_info *) node->value;
2845 ncond = rcli->condition;
2846 ncond = ior_reg_cond (ncond, cond, 1);
2847 if (rcli->stores == const0_rtx)
2848 rcli->stores = cond;
2849 else if (rcli->stores != const1_rtx)
2850 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
2852 /* If the register is now unconditionally dead, remove the entry
2853 in the splay_tree. A register is unconditionally dead if the
2854 dead condition ncond is true. A register is also unconditionally
2855 dead if the sum of all conditional stores is an unconditional
2856 store (stores is true), and the dead condition is identically the
2857 same as the original dead condition initialized at the end of
2858 the block. This is a pointer compare, not an rtx_equal_p
2860 if (ncond == const1_rtx
2861 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
2862 splay_tree_remove (pbi->reg_cond_dead, regno);
2865 rcli->condition = ncond;
2867 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2869 /* Not unconditionally dead. */
2878 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2881 free_reg_cond_life_info (value)
2882 splay_tree_value value;
2884 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
2888 /* Helper function for flush_reg_cond_reg. */
2891 flush_reg_cond_reg_1 (node, data)
2892 splay_tree_node node;
2895 struct reg_cond_life_info *rcli;
2896 int *xdata = (int *) data;
2897 unsigned int regno = xdata[0];
2899 /* Don't need to search if last flushed value was farther on in
2900 the in-order traversal. */
2901 if (xdata[1] >= (int) node->key)
2904 /* Splice out portions of the expression that refer to regno. */
2905 rcli = (struct reg_cond_life_info *) node->value;
2906 rcli->condition = elim_reg_cond (rcli->condition, regno);
2907 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
2908 rcli->stores = elim_reg_cond (rcli->stores, regno);
2910 /* If the entire condition is now false, signal the node to be removed. */
2911 if (rcli->condition == const0_rtx)
2913 xdata[1] = node->key;
2916 else if (rcli->condition == const1_rtx)
2922 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2925 flush_reg_cond_reg (pbi, regno)
2926 struct propagate_block_info *pbi;
2933 while (splay_tree_foreach (pbi->reg_cond_dead,
2934 flush_reg_cond_reg_1, pair) == -1)
2935 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
2937 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
2940 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2941 For ior/and, the ADD flag determines whether we want to add the new
2942 condition X to the old one unconditionally. If it is zero, we will
2943 only return a new expression if X allows us to simplify part of
2944 OLD, otherwise we return NULL to the caller.
2945 If ADD is nonzero, we will return a new condition in all cases. The
2946 toplevel caller of one of these functions should always pass 1 for
2950 ior_reg_cond (old, x, add)
2956 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
2958 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
2959 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
2960 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2962 if (GET_CODE (x) == GET_CODE (old)
2963 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2967 return gen_rtx_IOR (0, old, x);
2970 switch (GET_CODE (old))
2973 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
2974 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
2975 if (op0 != NULL || op1 != NULL)
2977 if (op0 == const0_rtx)
2978 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
2979 if (op1 == const0_rtx)
2980 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
2981 if (op0 == const1_rtx || op1 == const1_rtx)
2984 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
2985 else if (rtx_equal_p (x, op0))
2986 /* (x | A) | x ~ (x | A). */
2989 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
2990 else if (rtx_equal_p (x, op1))
2991 /* (A | x) | x ~ (A | x). */
2993 return gen_rtx_IOR (0, op0, op1);
2997 return gen_rtx_IOR (0, old, x);
3000 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3001 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3002 if (op0 != NULL || op1 != NULL)
3004 if (op0 == const1_rtx)
3005 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3006 if (op1 == const1_rtx)
3007 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3008 if (op0 == const0_rtx || op1 == const0_rtx)
3011 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3012 else if (rtx_equal_p (x, op0))
3013 /* (x & A) | x ~ x. */
3016 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3017 else if (rtx_equal_p (x, op1))
3018 /* (A & x) | x ~ x. */
3020 return gen_rtx_AND (0, op0, op1);
3024 return gen_rtx_IOR (0, old, x);
3027 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3029 return not_reg_cond (op0);
3032 return gen_rtx_IOR (0, old, x);
3043 enum rtx_code x_code;
3045 if (x == const0_rtx)
3047 else if (x == const1_rtx)
3049 x_code = GET_CODE (x);
3052 if (GET_RTX_CLASS (x_code) == '<'
3053 && GET_CODE (XEXP (x, 0)) == REG)
3055 if (XEXP (x, 1) != const0_rtx)
3058 return gen_rtx_fmt_ee (reverse_condition (x_code),
3059 VOIDmode, XEXP (x, 0), const0_rtx);
3061 return gen_rtx_NOT (0, x);
3065 and_reg_cond (old, x, add)
3071 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
3073 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
3074 && GET_CODE (x) == reverse_condition (GET_CODE (old))
3075 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3077 if (GET_CODE (x) == GET_CODE (old)
3078 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3082 return gen_rtx_AND (0, old, x);
3085 switch (GET_CODE (old))
3088 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3089 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3090 if (op0 != NULL || op1 != NULL)
3092 if (op0 == const0_rtx)
3093 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3094 if (op1 == const0_rtx)
3095 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3096 if (op0 == const1_rtx || op1 == const1_rtx)
3099 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3100 else if (rtx_equal_p (x, op0))
3101 /* (x | A) & x ~ x. */
3104 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3105 else if (rtx_equal_p (x, op1))
3106 /* (A | x) & x ~ x. */
3108 return gen_rtx_IOR (0, op0, op1);
3112 return gen_rtx_AND (0, old, x);
3115 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3116 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3117 if (op0 != NULL || op1 != NULL)
3119 if (op0 == const1_rtx)
3120 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3121 if (op1 == const1_rtx)
3122 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3123 if (op0 == const0_rtx || op1 == const0_rtx)
3126 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3127 else if (rtx_equal_p (x, op0))
3128 /* (x & A) & x ~ (x & A). */
3131 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3132 else if (rtx_equal_p (x, op1))
3133 /* (A & x) & x ~ (A & x). */
3135 return gen_rtx_AND (0, op0, op1);
3139 return gen_rtx_AND (0, old, x);
3142 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3144 return not_reg_cond (op0);
3147 return gen_rtx_AND (0, old, x);
3154 /* Given a condition X, remove references to reg REGNO and return the
3155 new condition. The removal will be done so that all conditions
3156 involving REGNO are considered to evaluate to false. This function
3157 is used when the value of REGNO changes. */
3160 elim_reg_cond (x, regno)
3166 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
3168 if (REGNO (XEXP (x, 0)) == regno)
3173 switch (GET_CODE (x))
3176 op0 = elim_reg_cond (XEXP (x, 0), regno);
3177 op1 = elim_reg_cond (XEXP (x, 1), regno);
3178 if (op0 == const0_rtx || op1 == const0_rtx)
3180 if (op0 == const1_rtx)
3182 if (op1 == const1_rtx)
3184 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3186 return gen_rtx_AND (0, op0, op1);
3189 op0 = elim_reg_cond (XEXP (x, 0), regno);
3190 op1 = elim_reg_cond (XEXP (x, 1), regno);
3191 if (op0 == const1_rtx || op1 == const1_rtx)
3193 if (op0 == const0_rtx)
3195 if (op1 == const0_rtx)
3197 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3199 return gen_rtx_IOR (0, op0, op1);
3202 op0 = elim_reg_cond (XEXP (x, 0), regno);
3203 if (op0 == const0_rtx)
3205 if (op0 == const1_rtx)
3207 if (op0 != XEXP (x, 0))
3208 return not_reg_cond (op0);
3215 #endif /* HAVE_conditional_execution */
3219 /* Try to substitute the auto-inc expression INC as the address inside
3220 MEM which occurs in INSN. Currently, the address of MEM is an expression
3221 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3222 that has a single set whose source is a PLUS of INCR_REG and something
3226 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
3227 struct propagate_block_info *pbi;
3228 rtx inc, insn, mem, incr, incr_reg;
3230 int regno = REGNO (incr_reg);
3231 rtx set = single_set (incr);
3232 rtx q = SET_DEST (set);
3233 rtx y = SET_SRC (set);
3234 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
3236 /* Make sure this reg appears only once in this insn. */
3237 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
3240 if (dead_or_set_p (incr, incr_reg)
3241 /* Mustn't autoinc an eliminable register. */
3242 && (regno >= FIRST_PSEUDO_REGISTER
3243 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
3245 /* This is the simple case. Try to make the auto-inc. If
3246 we can't, we are done. Otherwise, we will do any
3247 needed updates below. */
3248 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
3251 else if (GET_CODE (q) == REG
3252 /* PREV_INSN used here to check the semi-open interval
3254 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
3255 /* We must also check for sets of q as q may be
3256 a call clobbered hard register and there may
3257 be a call between PREV_INSN (insn) and incr. */
3258 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
3260 /* We have *p followed sometime later by q = p+size.
3261 Both p and q must be live afterward,
3262 and q is not used between INSN and its assignment.
3263 Change it to q = p, ...*q..., q = q+size.
3264 Then fall into the usual case. */
3268 emit_move_insn (q, incr_reg);
3269 insns = get_insns ();
3272 /* If we can't make the auto-inc, or can't make the
3273 replacement into Y, exit. There's no point in making
3274 the change below if we can't do the auto-inc and doing
3275 so is not correct in the pre-inc case. */
3278 validate_change (insn, &XEXP (mem, 0), inc, 1);
3279 validate_change (incr, &XEXP (y, opnum), q, 1);
3280 if (! apply_change_group ())
3283 /* We now know we'll be doing this change, so emit the
3284 new insn(s) and do the updates. */
3285 emit_insns_before (insns, insn);
3287 if (pbi->bb->head == insn)
3288 pbi->bb->head = insns;
3290 /* INCR will become a NOTE and INSN won't contain a
3291 use of INCR_REG. If a use of INCR_REG was just placed in
3292 the insn before INSN, make that the next use.
3293 Otherwise, invalidate it. */
3294 if (GET_CODE (PREV_INSN (insn)) == INSN
3295 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
3296 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
3297 pbi->reg_next_use[regno] = PREV_INSN (insn);
3299 pbi->reg_next_use[regno] = 0;
3304 /* REGNO is now used in INCR which is below INSN, but
3305 it previously wasn't live here. If we don't mark
3306 it as live, we'll put a REG_DEAD note for it
3307 on this insn, which is incorrect. */
3308 SET_REGNO_REG_SET (pbi->reg_live, regno);
3310 /* If there are any calls between INSN and INCR, show
3311 that REGNO now crosses them. */
3312 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
3313 if (GET_CODE (temp) == CALL_INSN)
3314 REG_N_CALLS_CROSSED (regno)++;
3316 /* Invalidate alias info for Q since we just changed its value. */
3317 clear_reg_alias_info (q);
3322 /* If we haven't returned, it means we were able to make the
3323 auto-inc, so update the status. First, record that this insn
3324 has an implicit side effect. */
3326 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
3328 /* Modify the old increment-insn to simply copy
3329 the already-incremented value of our register. */
3330 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
3333 /* If that makes it a no-op (copying the register into itself) delete
3334 it so it won't appear to be a "use" and a "set" of this
3336 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
3338 /* If the original source was dead, it's dead now. */
3341 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
3343 remove_note (incr, note);
3344 if (XEXP (note, 0) != incr_reg)
3345 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
3348 PUT_CODE (incr, NOTE);
3349 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
3350 NOTE_SOURCE_FILE (incr) = 0;
3353 if (regno >= FIRST_PSEUDO_REGISTER)
3355 /* Count an extra reference to the reg. When a reg is
3356 incremented, spilling it is worse, so we want to make
3357 that less likely. */
3358 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3360 /* Count the increment as a setting of the register,
3361 even though it isn't a SET in rtl. */
3362 REG_N_SETS (regno)++;
3366 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3370 find_auto_inc (pbi, x, insn)
3371 struct propagate_block_info *pbi;
3375 rtx addr = XEXP (x, 0);
3376 HOST_WIDE_INT offset = 0;
3377 rtx set, y, incr, inc_val;
3379 int size = GET_MODE_SIZE (GET_MODE (x));
3381 if (GET_CODE (insn) == JUMP_INSN)
3384 /* Here we detect use of an index register which might be good for
3385 postincrement, postdecrement, preincrement, or predecrement. */
3387 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
3388 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
3390 if (GET_CODE (addr) != REG)
3393 regno = REGNO (addr);
3395 /* Is the next use an increment that might make auto-increment? */
3396 incr = pbi->reg_next_use[regno];
3397 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
3399 set = single_set (incr);
3400 if (set == 0 || GET_CODE (set) != SET)
3404 if (GET_CODE (y) != PLUS)
3407 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
3408 inc_val = XEXP (y, 1);
3409 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
3410 inc_val = XEXP (y, 0);
3414 if (GET_CODE (inc_val) == CONST_INT)
3416 if (HAVE_POST_INCREMENT
3417 && (INTVAL (inc_val) == size && offset == 0))
3418 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
3420 else if (HAVE_POST_DECREMENT
3421 && (INTVAL (inc_val) == -size && offset == 0))
3422 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
3424 else if (HAVE_PRE_INCREMENT
3425 && (INTVAL (inc_val) == size && offset == size))
3426 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
3428 else if (HAVE_PRE_DECREMENT
3429 && (INTVAL (inc_val) == -size && offset == -size))
3430 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
3432 else if (HAVE_POST_MODIFY_DISP && offset == 0)
3433 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3434 gen_rtx_PLUS (Pmode,
3437 insn, x, incr, addr);
3439 else if (GET_CODE (inc_val) == REG
3440 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
3444 if (HAVE_POST_MODIFY_REG && offset == 0)
3445 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3446 gen_rtx_PLUS (Pmode,
3449 insn, x, incr, addr);
3453 #endif /* AUTO_INC_DEC */
3456 mark_used_reg (pbi, reg, cond, insn)
3457 struct propagate_block_info *pbi;
3459 rtx cond ATTRIBUTE_UNUSED;
3462 unsigned int regno_first, regno_last, i;
3463 int some_was_live, some_was_dead, some_not_set;
3465 regno_last = regno_first = REGNO (reg);
3466 if (regno_first < FIRST_PSEUDO_REGISTER)
3467 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
3469 /* Find out if any of this register is live after this instruction. */
3470 some_was_live = some_was_dead = 0;
3471 for (i = regno_first; i <= regno_last; ++i)
3473 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
3474 some_was_live |= needed_regno;
3475 some_was_dead |= ! needed_regno;
3478 /* Find out if any of the register was set this insn. */
3480 for (i = regno_first; i <= regno_last; ++i)
3481 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
3483 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3485 /* Record where each reg is used, so when the reg is set we know
3486 the next insn that uses it. */
3487 pbi->reg_next_use[regno_first] = insn;
3490 if (pbi->flags & PROP_REG_INFO)
3492 if (regno_first < FIRST_PSEUDO_REGISTER)
3494 /* If this is a register we are going to try to eliminate,
3495 don't mark it live here. If we are successful in
3496 eliminating it, it need not be live unless it is used for
3497 pseudos, in which case it will have been set live when it
3498 was allocated to the pseudos. If the register will not
3499 be eliminated, reload will set it live at that point.
3501 Otherwise, record that this function uses this register. */
3502 /* ??? The PPC backend tries to "eliminate" on the pic
3503 register to itself. This should be fixed. In the mean
3504 time, hack around it. */
3506 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
3507 && (regno_first == FRAME_POINTER_REGNUM
3508 || regno_first == ARG_POINTER_REGNUM)))
3509 for (i = regno_first; i <= regno_last; ++i)
3510 regs_ever_live[i] = 1;
3514 /* Keep track of which basic block each reg appears in. */
3516 int blocknum = pbi->bb->index;
3517 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
3518 REG_BASIC_BLOCK (regno_first) = blocknum;
3519 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
3520 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
3522 /* Count (weighted) number of uses of each reg. */
3523 REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb);
3524 REG_N_REFS (regno_first)++;
3528 /* Record and count the insns in which a reg dies. If it is used in
3529 this insn and was dead below the insn then it dies in this insn.
3530 If it was set in this insn, we do not make a REG_DEAD note;
3531 likewise if we already made such a note. */
3532 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
3536 /* Check for the case where the register dying partially
3537 overlaps the register set by this insn. */
3538 if (regno_first != regno_last)
3539 for (i = regno_first; i <= regno_last; ++i)
3540 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
3542 /* If none of the words in X is needed, make a REG_DEAD note.
3543 Otherwise, we must make partial REG_DEAD notes. */
3544 if (! some_was_live)
3546 if ((pbi->flags & PROP_DEATH_NOTES)
3547 && ! find_regno_note (insn, REG_DEAD, regno_first))
3549 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
3551 if (pbi->flags & PROP_REG_INFO)
3552 REG_N_DEATHS (regno_first)++;
3556 /* Don't make a REG_DEAD note for a part of a register
3557 that is set in the insn. */
3558 for (i = regno_first; i <= regno_last; ++i)
3559 if (! REGNO_REG_SET_P (pbi->reg_live, i)
3560 && ! dead_or_set_regno_p (insn, i))
3562 = alloc_EXPR_LIST (REG_DEAD,
3563 gen_rtx_REG (reg_raw_mode[i], i),
3568 /* Mark the register as being live. */
3569 for (i = regno_first; i <= regno_last; ++i)
3571 SET_REGNO_REG_SET (pbi->reg_live, i);
3573 #ifdef HAVE_conditional_execution
3574 /* If this is a conditional use, record that fact. If it is later
3575 conditionally set, we'll know to kill the register. */
3576 if (cond != NULL_RTX)
3578 splay_tree_node node;
3579 struct reg_cond_life_info *rcli;
3584 node = splay_tree_lookup (pbi->reg_cond_dead, i);
3587 /* The register was unconditionally live previously.
3588 No need to do anything. */
3592 /* The register was conditionally live previously.
3593 Subtract the new life cond from the old death cond. */
3594 rcli = (struct reg_cond_life_info *) node->value;
3595 ncond = rcli->condition;
3596 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
3598 /* If the register is now unconditionally live,
3599 remove the entry in the splay_tree. */
3600 if (ncond == const0_rtx)
3601 splay_tree_remove (pbi->reg_cond_dead, i);
3604 rcli->condition = ncond;
3605 SET_REGNO_REG_SET (pbi->reg_cond_reg,
3606 REGNO (XEXP (cond, 0)));
3612 /* The register was not previously live at all. Record
3613 the condition under which it is still dead. */
3614 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
3615 rcli->condition = not_reg_cond (cond);
3616 rcli->stores = const0_rtx;
3617 rcli->orig_condition = const0_rtx;
3618 splay_tree_insert (pbi->reg_cond_dead, i,
3619 (splay_tree_value) rcli);
3621 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
3624 else if (some_was_live)
3626 /* The register may have been conditionally live previously, but
3627 is now unconditionally live. Remove it from the conditionally
3628 dead list, so that a conditional set won't cause us to think
3630 splay_tree_remove (pbi->reg_cond_dead, i);
3636 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3637 This is done assuming the registers needed from X are those that
3638 have 1-bits in PBI->REG_LIVE.
3640 INSN is the containing instruction. If INSN is dead, this function
3644 mark_used_regs (pbi, x, cond, insn)
3645 struct propagate_block_info *pbi;
3650 int flags = pbi->flags;
3655 code = GET_CODE (x);
3676 /* If we are clobbering a MEM, mark any registers inside the address
3678 if (GET_CODE (XEXP (x, 0)) == MEM)
3679 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
3683 /* Don't bother watching stores to mems if this is not the
3684 final pass. We'll not be deleting dead stores this round. */
3685 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
3687 /* Invalidate the data for the last MEM stored, but only if MEM is
3688 something that can be stored into. */
3689 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3690 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3691 /* Needn't clear the memory set list. */
3695 rtx temp = pbi->mem_set_list;
3696 rtx prev = NULL_RTX;
3701 next = XEXP (temp, 1);
3702 if (anti_dependence (XEXP (temp, 0), x))
3704 /* Splice temp out of the list. */
3706 XEXP (prev, 1) = next;
3708 pbi->mem_set_list = next;
3709 free_EXPR_LIST_node (temp);
3710 pbi->mem_set_list_len--;
3718 /* If the memory reference had embedded side effects (autoincrement
3719 address modes. Then we may need to kill some entries on the
3722 invalidate_mems_from_autoinc (pbi, insn);
3726 if (flags & PROP_AUTOINC)
3727 find_auto_inc (pbi, x, insn);
3732 #ifdef CLASS_CANNOT_CHANGE_MODE
3733 if (GET_CODE (SUBREG_REG (x)) == REG
3734 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
3735 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
3736 GET_MODE (SUBREG_REG (x))))
3737 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
3740 /* While we're here, optimize this case. */
3742 if (GET_CODE (x) != REG)
3747 /* See a register other than being set => mark it as needed. */
3748 mark_used_reg (pbi, x, cond, insn);
3753 rtx testreg = SET_DEST (x);
3756 /* If storing into MEM, don't show it as being used. But do
3757 show the address as being used. */
3758 if (GET_CODE (testreg) == MEM)
3761 if (flags & PROP_AUTOINC)
3762 find_auto_inc (pbi, testreg, insn);
3764 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
3765 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3769 /* Storing in STRICT_LOW_PART is like storing in a reg
3770 in that this SET might be dead, so ignore it in TESTREG.
3771 but in some other ways it is like using the reg.
3773 Storing in a SUBREG or a bit field is like storing the entire
3774 register in that if the register's value is not used
3775 then this SET is not needed. */
3776 while (GET_CODE (testreg) == STRICT_LOW_PART
3777 || GET_CODE (testreg) == ZERO_EXTRACT
3778 || GET_CODE (testreg) == SIGN_EXTRACT
3779 || GET_CODE (testreg) == SUBREG)
3781 #ifdef CLASS_CANNOT_CHANGE_MODE
3782 if (GET_CODE (testreg) == SUBREG
3783 && GET_CODE (SUBREG_REG (testreg)) == REG
3784 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
3785 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
3786 GET_MODE (testreg)))
3787 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
3790 /* Modifying a single register in an alternate mode
3791 does not use any of the old value. But these other
3792 ways of storing in a register do use the old value. */
3793 if (GET_CODE (testreg) == SUBREG
3794 && !((REG_BYTES (SUBREG_REG (testreg))
3795 + UNITS_PER_WORD - 1) / UNITS_PER_WORD
3796 > (REG_BYTES (testreg)
3797 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
3802 testreg = XEXP (testreg, 0);
3805 /* If this is a store into a register or group of registers,
3806 recursively scan the value being stored. */
3808 if ((GET_CODE (testreg) == PARALLEL
3809 && GET_MODE (testreg) == BLKmode)
3810 || (GET_CODE (testreg) == REG
3811 && (regno = REGNO (testreg),
3812 ! (regno == FRAME_POINTER_REGNUM
3813 && (! reload_completed || frame_pointer_needed)))
3814 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3815 && ! (regno == HARD_FRAME_POINTER_REGNUM
3816 && (! reload_completed || frame_pointer_needed))
3818 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3819 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
3824 mark_used_regs (pbi, SET_DEST (x), cond, insn);
3825 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3832 case UNSPEC_VOLATILE:
3836 /* Traditional and volatile asm instructions must be considered to use
3837 and clobber all hard registers, all pseudo-registers and all of
3838 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3840 Consider for instance a volatile asm that changes the fpu rounding
3841 mode. An insn should not be moved across this even if it only uses
3842 pseudo-regs because it might give an incorrectly rounded result.
3844 ?!? Unfortunately, marking all hard registers as live causes massive
3845 problems for the register allocator and marking all pseudos as live
3846 creates mountains of uninitialized variable warnings.
3848 So for now, just clear the memory set list and mark any regs
3849 we can find in ASM_OPERANDS as used. */
3850 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
3852 free_EXPR_LIST_list (&pbi->mem_set_list);
3853 pbi->mem_set_list_len = 0;
3856 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3857 We can not just fall through here since then we would be confused
3858 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3859 traditional asms unlike their normal usage. */
3860 if (code == ASM_OPERANDS)
3864 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
3865 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
3871 if (cond != NULL_RTX)
3874 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
3876 cond = COND_EXEC_TEST (x);
3877 x = COND_EXEC_CODE (x);
3881 /* We _do_not_ want to scan operands of phi nodes. Operands of
3882 a phi function are evaluated only when control reaches this
3883 block along a particular edge. Therefore, regs that appear
3884 as arguments to phi should not be added to the global live at
3892 /* Recursively scan the operands of this expression. */
3895 const char * const fmt = GET_RTX_FORMAT (code);
3898 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3902 /* Tail recursive case: save a function call level. */
3908 mark_used_regs (pbi, XEXP (x, i), cond, insn);
3910 else if (fmt[i] == 'E')
3913 for (j = 0; j < XVECLEN (x, i); j++)
3914 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
3923 try_pre_increment_1 (pbi, insn)
3924 struct propagate_block_info *pbi;
3927 /* Find the next use of this reg. If in same basic block,
3928 make it do pre-increment or pre-decrement if appropriate. */
3929 rtx x = single_set (insn);
3930 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
3931 * INTVAL (XEXP (SET_SRC (x), 1)));
3932 int regno = REGNO (SET_DEST (x));
3933 rtx y = pbi->reg_next_use[regno];
3935 && SET_DEST (x) != stack_pointer_rtx
3936 && BLOCK_NUM (y) == BLOCK_NUM (insn)
3937 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3938 mode would be better. */
3939 && ! dead_or_set_p (y, SET_DEST (x))
3940 && try_pre_increment (y, SET_DEST (x), amount))
3942 /* We have found a suitable auto-increment and already changed
3943 insn Y to do it. So flush this increment instruction. */
3944 propagate_block_delete_insn (pbi->bb, insn);
3946 /* Count a reference to this reg for the increment insn we are
3947 deleting. When a reg is incremented, spilling it is worse,
3948 so we want to make that less likely. */
3949 if (regno >= FIRST_PSEUDO_REGISTER)
3951 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3952 REG_N_SETS (regno)++;
3955 /* Flush any remembered memories depending on the value of
3956 the incremented register. */
3957 invalidate_mems_from_set (pbi, SET_DEST (x));
3964 /* Try to change INSN so that it does pre-increment or pre-decrement
3965 addressing on register REG in order to add AMOUNT to REG.
3966 AMOUNT is negative for pre-decrement.
3967 Returns 1 if the change could be made.
3968 This checks all about the validity of the result of modifying INSN. */
3971 try_pre_increment (insn, reg, amount)
3973 HOST_WIDE_INT amount;
3977 /* Nonzero if we can try to make a pre-increment or pre-decrement.
3978 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
3980 /* Nonzero if we can try to make a post-increment or post-decrement.
3981 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
3982 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
3983 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
3986 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
3989 /* From the sign of increment, see which possibilities are conceivable
3990 on this target machine. */
3991 if (HAVE_PRE_INCREMENT && amount > 0)
3993 if (HAVE_POST_INCREMENT && amount > 0)
3996 if (HAVE_PRE_DECREMENT && amount < 0)
3998 if (HAVE_POST_DECREMENT && amount < 0)
4001 if (! (pre_ok || post_ok))
4004 /* It is not safe to add a side effect to a jump insn
4005 because if the incremented register is spilled and must be reloaded
4006 there would be no way to store the incremented value back in memory. */
4008 if (GET_CODE (insn) == JUMP_INSN)
4013 use = find_use_as_address (PATTERN (insn), reg, 0);
4014 if (post_ok && (use == 0 || use == (rtx) (size_t) 1))
4016 use = find_use_as_address (PATTERN (insn), reg, -amount);
4020 if (use == 0 || use == (rtx) (size_t) 1)
4023 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
4026 /* See if this combination of instruction and addressing mode exists. */
4027 if (! validate_change (insn, &XEXP (use, 0),
4028 gen_rtx_fmt_e (amount > 0
4029 ? (do_post ? POST_INC : PRE_INC)
4030 : (do_post ? POST_DEC : PRE_DEC),
4034 /* Record that this insn now has an implicit side effect on X. */
4035 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
4039 #endif /* AUTO_INC_DEC */
4041 /* Find the place in the rtx X where REG is used as a memory address.
4042 Return the MEM rtx that so uses it.
4043 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4044 (plus REG (const_int PLUSCONST)).
4046 If such an address does not appear, return 0.
4047 If REG appears more than once, or is used other than in such an address,
4051 find_use_as_address (x, reg, plusconst)
4054 HOST_WIDE_INT plusconst;
4056 enum rtx_code code = GET_CODE (x);
4057 const char * const fmt = GET_RTX_FORMAT (code);
4062 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
4065 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
4066 && XEXP (XEXP (x, 0), 0) == reg
4067 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
4068 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
4071 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
4073 /* If REG occurs inside a MEM used in a bit-field reference,
4074 that is unacceptable. */
4075 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
4076 return (rtx) (size_t) 1;
4080 return (rtx) (size_t) 1;
4082 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4086 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
4090 return (rtx) (size_t) 1;
4092 else if (fmt[i] == 'E')
4095 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4097 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
4101 return (rtx) (size_t) 1;
4109 /* Write information about registers and basic blocks into FILE.
4110 This is part of making a debugging dump. */
4113 dump_regset (r, outf)
4120 fputs (" (nil)", outf);
4124 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
4126 fprintf (outf, " %d", i);
4127 if (i < FIRST_PSEUDO_REGISTER)
4128 fprintf (outf, " [%s]",
4133 /* Print a human-reaable representation of R on the standard error
4134 stream. This function is designed to be used from within the
4141 dump_regset (r, stderr);
4142 putc ('\n', stderr);
4145 /* Recompute register set/reference counts immediately prior to register
4148 This avoids problems with set/reference counts changing to/from values
4149 which have special meanings to the register allocators.
4151 Additionally, the reference counts are the primary component used by the
4152 register allocators to prioritize pseudos for allocation to hard regs.
4153 More accurate reference counts generally lead to better register allocation.
4155 F is the first insn to be scanned.
4157 LOOP_STEP denotes how much loop_depth should be incremented per
4158 loop nesting level in order to increase the ref count more for
4159 references in a loop.
4161 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4162 possibly other information which is used by the register allocators. */
4165 recompute_reg_usage (f, loop_step)
4166 rtx f ATTRIBUTE_UNUSED;
4167 int loop_step ATTRIBUTE_UNUSED;
4169 allocate_reg_life_data ();
4170 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
4173 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4174 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4175 of the number of registers that died. */
4178 count_or_remove_death_notes (blocks, kill)
4184 for (i = n_basic_blocks - 1; i >= 0; --i)
4189 if (blocks && ! TEST_BIT (blocks, i))
4192 bb = BASIC_BLOCK (i);
4194 for (insn = bb->head;; insn = NEXT_INSN (insn))
4198 rtx *pprev = ®_NOTES (insn);
4203 switch (REG_NOTE_KIND (link))
4206 if (GET_CODE (XEXP (link, 0)) == REG)
4208 rtx reg = XEXP (link, 0);
4211 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
4214 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
4222 rtx next = XEXP (link, 1);
4223 free_EXPR_LIST_node (link);
4224 *pprev = link = next;
4230 pprev = &XEXP (link, 1);
4237 if (insn == bb->end)
4244 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4245 if blocks is NULL. */
4248 clear_log_links (blocks)
4256 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4258 free_INSN_LIST_list (&LOG_LINKS (insn));
4261 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4263 basic_block bb = BASIC_BLOCK (i);
4265 for (insn = bb->head; insn != NEXT_INSN (bb->end);
4266 insn = NEXT_INSN (insn))
4268 free_INSN_LIST_list (&LOG_LINKS (insn));
4272 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4273 correspond to the hard registers, if any, set in that map. This
4274 could be done far more efficiently by having all sorts of special-cases
4275 with moving single words, but probably isn't worth the trouble. */
4278 reg_set_to_hard_reg_set (to, from)
4284 EXECUTE_IF_SET_IN_BITMAP
4287 if (i >= FIRST_PSEUDO_REGISTER)
4289 SET_HARD_REG_BIT (*to, i);