1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 /* This file contains the data flow analysis pass of the compiler. It
23 computes data flow information which tells combine_instructions
24 which insns to consider combining and controls register allocation.
26 Additional data flow information that is too bulky to record is
27 generated during the analysis, and is used at that time to create
28 autoincrement and autodecrement addressing.
30 The first step is dividing the function into basic blocks.
31 find_basic_blocks does this. Then life_analysis determines
32 where each register is live and where it is dead.
34 ** find_basic_blocks **
36 find_basic_blocks divides the current function's rtl into basic
37 blocks and constructs the CFG. The blocks are recorded in the
38 basic_block_info array; the CFG exists in the edge structures
39 referenced by the blocks.
41 find_basic_blocks also finds any unreachable loops and deletes them.
45 life_analysis is called immediately after find_basic_blocks.
46 It uses the basic block information to determine where each
47 hard or pseudo register is live.
49 ** live-register info **
51 The information about where each register is live is in two parts:
52 the REG_NOTES of insns, and the vector basic_block->global_live_at_start.
54 basic_block->global_live_at_start has an element for each basic
55 block, and the element is a bit-vector with a bit for each hard or
56 pseudo register. The bit is 1 if the register is live at the
57 beginning of the basic block.
59 Two types of elements can be added to an insn's REG_NOTES.
60 A REG_DEAD note is added to an insn's REG_NOTES for any register
61 that meets both of two conditions: The value in the register is not
62 needed in subsequent insns and the insn does not replace the value in
63 the register (in the case of multi-word hard registers, the value in
64 each register must be replaced by the insn to avoid a REG_DEAD note).
66 In the vast majority of cases, an object in a REG_DEAD note will be
67 used somewhere in the insn. The (rare) exception to this is if an
68 insn uses a multi-word hard register and only some of the registers are
69 needed in subsequent insns. In that case, REG_DEAD notes will be
70 provided for those hard registers that are not subsequently needed.
71 Partial REG_DEAD notes of this type do not occur when an insn sets
72 only some of the hard registers used in such a multi-word operand;
73 omitting REG_DEAD notes for objects stored in an insn is optional and
74 the desire to do so does not justify the complexity of the partial
77 REG_UNUSED notes are added for each register that is set by the insn
78 but is unused subsequently (if every register set by the insn is unused
79 and the insn does not reference memory or have some other side-effect,
80 the insn is deleted instead). If only part of a multi-word hard
81 register is used in a subsequent insn, REG_UNUSED notes are made for
82 the parts that will not be used.
84 To determine which registers are live after any insn, one can
85 start from the beginning of the basic block and scan insns, noting
86 which registers are set by each insn and which die there.
88 ** Other actions of life_analysis **
90 life_analysis sets up the LOG_LINKS fields of insns because the
91 information needed to do so is readily available.
93 life_analysis deletes insns whose only effect is to store a value
96 life_analysis notices cases where a reference to a register as
97 a memory address can be combined with a preceding or following
98 incrementation or decrementation of the register. The separate
99 instruction to increment or decrement is deleted and the address
100 is changed to a POST_INC or similar rtx.
102 Each time an incrementing or decrementing address is created,
103 a REG_INC element is added to the insn's REG_NOTES list.
105 life_analysis fills in certain vectors containing information about
106 register usage: REG_N_REFS, REG_N_DEATHS, REG_N_SETS, REG_LIVE_LENGTH,
107 REG_N_CALLS_CROSSED and REG_BASIC_BLOCK.
109 life_analysis sets current_function_sp_is_unchanging if the function
110 doesn't modify the stack pointer. */
114 Split out from life_analysis:
115 - local property discovery (bb->local_live, bb->local_set)
116 - global property computation
118 - pre/post modify transformation
123 #include "coretypes.h"
128 #include "hard-reg-set.h"
129 #include "basic-block.h"
130 #include "insn-config.h"
134 #include "function.h"
142 #include "splay-tree.h"
144 #ifndef HAVE_epilogue
145 #define HAVE_epilogue 0
147 #ifndef HAVE_prologue
148 #define HAVE_prologue 0
150 #ifndef HAVE_sibcall_epilogue
151 #define HAVE_sibcall_epilogue 0
154 #ifndef EPILOGUE_USES
155 #define EPILOGUE_USES(REGNO) 0
158 #define EH_USES(REGNO) 0
161 #ifdef HAVE_conditional_execution
162 #ifndef REVERSE_CONDEXEC_PREDICATES_P
163 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y))
167 /* Nonzero if the second flow pass has completed. */
170 /* Maximum register number used in this function, plus one. */
174 /* Indexed by n, giving various register information */
176 varray_type reg_n_info;
178 /* Size of a regset for the current function,
179 in (1) bytes and (2) elements. */
184 /* Regset of regs live when calls to `setjmp'-like functions happen. */
185 /* ??? Does this exist only for the setjmp-clobbered warning message? */
187 regset regs_live_at_setjmp;
189 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
190 that have to go in the same hard reg.
191 The first two regs in the list are a pair, and the next two
192 are another pair, etc. */
195 /* Callback that determines if it's ok for a function to have no
196 noreturn attribute. */
197 int (*lang_missing_noreturn_ok_p) (tree);
199 /* Set of registers that may be eliminable. These are handled specially
200 in updating regs_ever_live. */
202 static HARD_REG_SET elim_reg_set;
204 /* Holds information for tracking conditional register life information. */
205 struct reg_cond_life_info
207 /* A boolean expression of conditions under which a register is dead. */
209 /* Conditions under which a register is dead at the basic block end. */
212 /* A boolean expression of conditions under which a register has been
216 /* ??? Could store mask of bytes that are dead, so that we could finally
217 track lifetimes of multi-word registers accessed via subregs. */
220 /* For use in communicating between propagate_block and its subroutines.
221 Holds all information needed to compute life and def-use information. */
223 struct propagate_block_info
225 /* The basic block we're considering. */
228 /* Bit N is set if register N is conditionally or unconditionally live. */
231 /* Bit N is set if register N is set this insn. */
234 /* Element N is the next insn that uses (hard or pseudo) register N
235 within the current basic block; or zero, if there is no such insn. */
238 /* Contains a list of all the MEMs we are tracking for dead store
242 /* If non-null, record the set of registers set unconditionally in the
246 /* If non-null, record the set of registers set conditionally in the
248 regset cond_local_set;
250 #ifdef HAVE_conditional_execution
251 /* Indexed by register number, holds a reg_cond_life_info for each
252 register that is not unconditionally live or dead. */
253 splay_tree reg_cond_dead;
255 /* Bit N is set if register N is in an expression in reg_cond_dead. */
259 /* The length of mem_set_list. */
260 int mem_set_list_len;
262 /* Nonzero if the value of CC0 is live. */
265 /* Flags controlling the set of information propagate_block collects. */
267 /* Index of instruction being processed. */
271 /* Number of dead insns removed. */
274 /* When PROP_REG_INFO set, array contains pbi->insn_num of instruction
275 where given register died. When the register is marked alive, we use the
276 information to compute amount of instructions life range cross.
277 (remember, we are walking backward). This can be computed as current
278 pbi->insn_num - reg_deaths[regno].
279 At the end of processing each basic block, the remaining live registers
280 are inspected and liferanges are increased same way so liverange of global
281 registers are computed correctly.
283 The array is maintained clear for dead registers, so it can be safely reused
284 for next basic block without expensive memset of the whole array after
285 reseting pbi->insn_num to 0. */
287 static int *reg_deaths;
289 /* Maximum length of pbi->mem_set_list before we start dropping
290 new elements on the floor. */
291 #define MAX_MEM_SET_LIST_LEN 100
293 /* Forward declarations */
294 static int verify_wide_reg_1 (rtx *, void *);
295 static void verify_wide_reg (int, basic_block);
296 static void verify_local_live_at_start (regset, basic_block);
297 static void notice_stack_pointer_modification_1 (rtx, rtx, void *);
298 static void notice_stack_pointer_modification (rtx);
299 static void mark_reg (rtx, void *);
300 static void mark_regs_live_at_end (regset);
301 static void calculate_global_regs_live (sbitmap, sbitmap, int);
302 static void propagate_block_delete_insn (rtx);
303 static rtx propagate_block_delete_libcall (rtx, rtx);
304 static int insn_dead_p (struct propagate_block_info *, rtx, int, rtx);
305 static int libcall_dead_p (struct propagate_block_info *, rtx, rtx);
306 static void mark_set_regs (struct propagate_block_info *, rtx, rtx);
307 static void mark_set_1 (struct propagate_block_info *, enum rtx_code, rtx,
309 static int find_regno_partial (rtx *, void *);
311 #ifdef HAVE_conditional_execution
312 static int mark_regno_cond_dead (struct propagate_block_info *, int, rtx);
313 static void free_reg_cond_life_info (splay_tree_value);
314 static int flush_reg_cond_reg_1 (splay_tree_node, void *);
315 static void flush_reg_cond_reg (struct propagate_block_info *, int);
316 static rtx elim_reg_cond (rtx, unsigned int);
317 static rtx ior_reg_cond (rtx, rtx, int);
318 static rtx not_reg_cond (rtx);
319 static rtx and_reg_cond (rtx, rtx, int);
322 static void attempt_auto_inc (struct propagate_block_info *, rtx, rtx, rtx,
324 static void find_auto_inc (struct propagate_block_info *, rtx, rtx);
325 static int try_pre_increment_1 (struct propagate_block_info *, rtx);
326 static int try_pre_increment (rtx, rtx, HOST_WIDE_INT);
328 static void mark_used_reg (struct propagate_block_info *, rtx, rtx, rtx);
329 static void mark_used_regs (struct propagate_block_info *, rtx, rtx, rtx);
330 void debug_flow_info (void);
331 static void add_to_mem_set_list (struct propagate_block_info *, rtx);
332 static int invalidate_mems_from_autoinc (rtx *, void *);
333 static void invalidate_mems_from_set (struct propagate_block_info *, rtx);
334 static void clear_log_links (sbitmap);
335 static int count_or_remove_death_notes_bb (basic_block, int);
339 check_function_return_warnings (void)
341 if (warn_missing_noreturn
342 && !TREE_THIS_VOLATILE (cfun->decl)
343 && EXIT_BLOCK_PTR->pred == NULL
344 && (lang_missing_noreturn_ok_p
345 && !lang_missing_noreturn_ok_p (cfun->decl)))
346 warning ("function might be possible candidate for attribute `noreturn'");
348 /* If we have a path to EXIT, then we do return. */
349 if (TREE_THIS_VOLATILE (cfun->decl)
350 && EXIT_BLOCK_PTR->pred != NULL)
351 warning ("`noreturn' function does return");
353 /* If the clobber_return_insn appears in some basic block, then we
354 do reach the end without returning a value. */
355 else if (warn_return_type
356 && cfun->x_clobber_return_insn != NULL
357 && EXIT_BLOCK_PTR->pred != NULL)
359 int max_uid = get_max_uid ();
361 /* If clobber_return_insn was excised by jump1, then renumber_insns
362 can make max_uid smaller than the number still recorded in our rtx.
363 That's fine, since this is a quick way of verifying that the insn
364 is no longer in the chain. */
365 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
369 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
370 if (insn == cfun->x_clobber_return_insn)
372 warning ("control reaches end of non-void function");
379 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
380 note associated with the BLOCK. */
383 first_insn_after_basic_block_note (basic_block block)
387 /* Get the first instruction in the block. */
388 insn = BB_HEAD (block);
390 if (insn == NULL_RTX)
392 if (GET_CODE (insn) == CODE_LABEL)
393 insn = NEXT_INSN (insn);
394 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
397 return NEXT_INSN (insn);
400 /* Perform data flow analysis.
401 F is the first insn of the function; FLAGS is a set of PROP_* flags
402 to be used in accumulating flow info. */
405 life_analysis (rtx f, FILE *file, int flags)
407 #ifdef ELIMINABLE_REGS
409 static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS;
412 /* Record which registers will be eliminated. We use this in
415 CLEAR_HARD_REG_SET (elim_reg_set);
417 #ifdef ELIMINABLE_REGS
418 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
419 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
421 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
425 #ifdef CANNOT_CHANGE_MODE_CLASS
426 if (flags & PROP_REG_INFO)
427 bitmap_initialize (&subregs_of_mode, 1);
431 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES);
433 /* The post-reload life analysis have (on a global basis) the same
434 registers live as was computed by reload itself. elimination
435 Otherwise offsets and such may be incorrect.
437 Reload will make some registers as live even though they do not
440 We don't want to create new auto-incs after reload, since they
441 are unlikely to be useful and can cause problems with shared
443 if (reload_completed)
444 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
446 /* We want alias analysis information for local dead store elimination. */
447 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
448 init_alias_analysis ();
450 /* Always remove no-op moves. Do this before other processing so
451 that we don't have to keep re-scanning them. */
452 delete_noop_moves (f);
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)
474 memset (regs_ever_live, 0, sizeof (regs_ever_live));
475 memset (regs_asm_clobbered, 0, sizeof (regs_asm_clobbered));
477 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
485 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
486 end_alias_analysis ();
489 dump_flow_info (file);
491 free_basic_block_vars (1);
493 /* Removing dead insns should have made jumptables really dead. */
494 delete_dead_jumptables ();
497 /* A subroutine of verify_wide_reg, called through for_each_rtx.
498 Search for REGNO. If found, return 2 if it is not wider than
502 verify_wide_reg_1 (rtx *px, void *pregno)
505 unsigned int regno = *(int *) pregno;
507 if (GET_CODE (x) == REG && REGNO (x) == regno)
509 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
516 /* A subroutine of verify_local_live_at_start. Search through insns
517 of BB looking for register REGNO. */
520 verify_wide_reg (int regno, basic_block bb)
522 rtx head = BB_HEAD (bb), end = BB_END (bb);
528 int r = for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no);
536 head = NEXT_INSN (head);
541 fprintf (dump_file, "Register %d died unexpectedly.\n", regno);
542 dump_bb (bb, dump_file, 0);
547 /* A subroutine of update_life_info. Verify that there are no untoward
548 changes in live_at_start during a local update. */
551 verify_local_live_at_start (regset new_live_at_start, basic_block bb)
553 if (reload_completed)
555 /* After reload, there are no pseudos, nor subregs of multi-word
556 registers. The regsets should exactly match. */
557 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
562 "live_at_start mismatch in bb %d, aborting\nNew:\n",
564 debug_bitmap_file (dump_file, new_live_at_start);
565 fputs ("Old:\n", dump_file);
566 dump_bb (bb, dump_file, 0);
575 /* Find the set of changed registers. */
576 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
578 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
580 /* No registers should die. */
581 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
586 "Register %d died unexpectedly.\n", i);
587 dump_bb (bb, dump_file, 0);
592 /* Verify that the now-live register is wider than word_mode. */
593 verify_wide_reg (i, bb);
598 /* Updates life information starting with the basic blocks set in BLOCKS.
599 If BLOCKS is null, consider it to be the universal set.
601 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholing,
602 we are only expecting local modifications to basic blocks. If we find
603 extra registers live at the beginning of a block, then we either killed
604 useful data, or we have a broken split that wants data not provided.
605 If we find registers removed from live_at_start, that means we have
606 a broken peephole that is killing a register it shouldn't.
608 ??? This is not true in one situation -- when a pre-reload splitter
609 generates subregs of a multi-word pseudo, current life analysis will
610 lose the kill. So we _can_ have a pseudo go live. How irritating.
612 It is also not true when a peephole decides that it doesn't need one
613 or more of the inputs.
615 Including PROP_REG_INFO does not properly refresh regs_ever_live
616 unless the caller resets it to zero. */
619 update_life_info (sbitmap blocks, enum update_life_extent extent, int prop_flags)
622 regset_head tmp_head;
624 int stabilized_prop_flags = prop_flags;
627 tmp = INITIALIZE_REG_SET (tmp_head);
630 if ((prop_flags & PROP_REG_INFO) && !reg_deaths)
631 reg_deaths = xcalloc (sizeof (*reg_deaths), max_regno);
633 timevar_push ((extent == UPDATE_LIFE_LOCAL || blocks)
634 ? TV_LIFE_UPDATE : TV_LIFE);
636 /* Changes to the CFG are only allowed when
637 doing a global update for the entire CFG. */
638 if ((prop_flags & PROP_ALLOW_CFG_CHANGES)
639 && (extent == UPDATE_LIFE_LOCAL || blocks))
642 /* For a global update, we go through the relaxation process again. */
643 if (extent != UPDATE_LIFE_LOCAL)
649 calculate_global_regs_live (blocks, blocks,
650 prop_flags & (PROP_SCAN_DEAD_CODE
651 | PROP_SCAN_DEAD_STORES
652 | PROP_ALLOW_CFG_CHANGES));
654 if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
655 != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
658 /* Removing dead code may allow the CFG to be simplified which
659 in turn may allow for further dead code detection / removal. */
660 FOR_EACH_BB_REVERSE (bb)
662 COPY_REG_SET (tmp, bb->global_live_at_end);
663 changed |= propagate_block (bb, tmp, NULL, NULL,
664 prop_flags & (PROP_SCAN_DEAD_CODE
665 | PROP_SCAN_DEAD_STORES
666 | PROP_KILL_DEAD_CODE));
669 /* Don't pass PROP_SCAN_DEAD_CODE or PROP_KILL_DEAD_CODE to
670 subsequent propagate_block calls, since removing or acting as
671 removing dead code can affect global register liveness, which
672 is supposed to be finalized for this call after this loop. */
673 stabilized_prop_flags
674 &= ~(PROP_SCAN_DEAD_CODE | PROP_SCAN_DEAD_STORES
675 | PROP_KILL_DEAD_CODE);
680 /* We repeat regardless of what cleanup_cfg says. If there were
681 instructions deleted above, that might have been only a
682 partial improvement (see MAX_MEM_SET_LIST_LEN usage).
683 Further improvement may be possible. */
684 cleanup_cfg (CLEANUP_EXPENSIVE);
686 /* Zap the life information from the last round. If we don't
687 do this, we can wind up with registers that no longer appear
688 in the code being marked live at entry, which twiggs bogus
689 warnings from regno_uninitialized. */
692 CLEAR_REG_SET (bb->global_live_at_start);
693 CLEAR_REG_SET (bb->global_live_at_end);
697 /* If asked, remove notes from the blocks we'll update. */
698 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
699 count_or_remove_death_notes (blocks, 1);
702 /* Clear log links in case we are asked to (re)compute them. */
703 if (prop_flags & PROP_LOG_LINKS)
704 clear_log_links (blocks);
708 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
710 bb = BASIC_BLOCK (i);
712 COPY_REG_SET (tmp, bb->global_live_at_end);
713 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags);
715 if (extent == UPDATE_LIFE_LOCAL)
716 verify_local_live_at_start (tmp, bb);
721 FOR_EACH_BB_REVERSE (bb)
723 COPY_REG_SET (tmp, bb->global_live_at_end);
725 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags);
727 if (extent == UPDATE_LIFE_LOCAL)
728 verify_local_live_at_start (tmp, bb);
734 if (prop_flags & PROP_REG_INFO)
736 /* The only pseudos that are live at the beginning of the function
737 are those that were not set anywhere in the function. local-alloc
738 doesn't know how to handle these correctly, so mark them as not
739 local to any one basic block. */
740 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
741 FIRST_PSEUDO_REGISTER, i,
742 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
744 /* We have a problem with any pseudoreg that lives across the setjmp.
745 ANSI says that if a user variable does not change in value between
746 the setjmp and the longjmp, then the longjmp preserves it. This
747 includes longjmp from a place where the pseudo appears dead.
748 (In principle, the value still exists if it is in scope.)
749 If the pseudo goes in a hard reg, some other value may occupy
750 that hard reg where this pseudo is dead, thus clobbering the pseudo.
751 Conclusion: such a pseudo must not go in a hard reg. */
752 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
753 FIRST_PSEUDO_REGISTER, i,
755 if (regno_reg_rtx[i] != 0)
757 REG_LIVE_LENGTH (i) = -1;
758 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
767 timevar_pop ((extent == UPDATE_LIFE_LOCAL || blocks)
768 ? TV_LIFE_UPDATE : TV_LIFE);
769 if (ndead && dump_file)
770 fprintf (dump_file, "deleted %i dead insns\n", ndead);
774 /* Update life information in all blocks where BB_DIRTY is set. */
777 update_life_info_in_dirty_blocks (enum update_life_extent extent, int prop_flags)
779 sbitmap update_life_blocks = sbitmap_alloc (last_basic_block);
784 sbitmap_zero (update_life_blocks);
787 if (extent == UPDATE_LIFE_LOCAL)
789 if (bb->flags & BB_DIRTY)
791 SET_BIT (update_life_blocks, bb->index);
797 /* ??? Bootstrap with -march=pentium4 fails to terminate
798 with only a partial life update. */
799 SET_BIT (update_life_blocks, bb->index);
800 if (bb->flags & BB_DIRTY)
806 retval = update_life_info (update_life_blocks, extent, prop_flags);
808 sbitmap_free (update_life_blocks);
812 /* Free the variables allocated by find_basic_blocks.
814 KEEP_HEAD_END_P is nonzero if basic_block_info is not to be freed. */
817 free_basic_block_vars (int keep_head_end_p)
819 if (! keep_head_end_p)
821 if (basic_block_info)
824 VARRAY_FREE (basic_block_info);
827 last_basic_block = 0;
829 ENTRY_BLOCK_PTR->aux = NULL;
830 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
831 EXIT_BLOCK_PTR->aux = NULL;
832 EXIT_BLOCK_PTR->global_live_at_start = NULL;
836 /* Delete any insns that copy a register to itself. */
839 delete_noop_moves (rtx f ATTRIBUTE_UNUSED)
847 for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb)); insn = next)
849 next = NEXT_INSN (insn);
850 if (INSN_P (insn) && noop_move_p (insn))
854 /* If we're about to remove the first insn of a libcall
855 then move the libcall note to the next real insn and
856 update the retval note. */
857 if ((note = find_reg_note (insn, REG_LIBCALL, NULL_RTX))
858 && XEXP (note, 0) != insn)
860 rtx new_libcall_insn = next_real_insn (insn);
861 rtx retval_note = find_reg_note (XEXP (note, 0),
862 REG_RETVAL, NULL_RTX);
863 REG_NOTES (new_libcall_insn)
864 = gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0),
865 REG_NOTES (new_libcall_insn));
866 XEXP (retval_note, 0) = new_libcall_insn;
869 delete_insn_and_edges (insn);
874 if (nnoops && dump_file)
875 fprintf (dump_file, "deleted %i noop moves", nnoops);
879 /* Delete any jump tables never referenced. We can't delete them at the
880 time of removing tablejump insn as they are referenced by the preceding
881 insns computing the destination, so we delay deleting and garbagecollect
882 them once life information is computed. */
884 delete_dead_jumptables (void)
887 for (insn = get_insns (); insn; insn = next)
889 next = NEXT_INSN (insn);
890 if (GET_CODE (insn) == CODE_LABEL
891 && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
892 && GET_CODE (next) == JUMP_INSN
893 && (GET_CODE (PATTERN (next)) == ADDR_VEC
894 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
897 fprintf (dump_file, "Dead jumptable %i removed\n", INSN_UID (insn));
898 delete_insn (NEXT_INSN (insn));
900 next = NEXT_INSN (next);
905 /* Determine if the stack pointer is constant over the life of the function.
906 Only useful before prologues have been emitted. */
909 notice_stack_pointer_modification_1 (rtx x, rtx pat ATTRIBUTE_UNUSED,
910 void *data ATTRIBUTE_UNUSED)
912 if (x == stack_pointer_rtx
913 /* The stack pointer is only modified indirectly as the result
914 of a push until later in flow. See the comments in rtl.texi
915 regarding Embedded Side-Effects on Addresses. */
916 || (GET_CODE (x) == MEM
917 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
918 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
919 current_function_sp_is_unchanging = 0;
923 notice_stack_pointer_modification (rtx f)
927 /* Assume that the stack pointer is unchanging if alloca hasn't
929 current_function_sp_is_unchanging = !current_function_calls_alloca;
930 if (! current_function_sp_is_unchanging)
933 for (insn = f; insn; insn = NEXT_INSN (insn))
937 /* Check if insn modifies the stack pointer. */
938 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
940 if (! current_function_sp_is_unchanging)
946 /* Mark a register in SET. Hard registers in large modes get all
947 of their component registers set as well. */
950 mark_reg (rtx reg, void *xset)
952 regset set = (regset) xset;
953 int regno = REGNO (reg);
955 if (GET_MODE (reg) == BLKmode)
958 SET_REGNO_REG_SET (set, regno);
959 if (regno < FIRST_PSEUDO_REGISTER)
961 int n = hard_regno_nregs[regno][GET_MODE (reg)];
963 SET_REGNO_REG_SET (set, regno + n);
967 /* Mark those regs which are needed at the end of the function as live
968 at the end of the last basic block. */
971 mark_regs_live_at_end (regset set)
975 /* If exiting needs the right stack value, consider the stack pointer
976 live at the end of the function. */
977 if ((HAVE_epilogue && epilogue_completed)
978 || ! EXIT_IGNORE_STACK
979 || (! FRAME_POINTER_REQUIRED
980 && ! current_function_calls_alloca
981 && flag_omit_frame_pointer)
982 || current_function_sp_is_unchanging)
984 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
987 /* Mark the frame pointer if needed at the end of the function. If
988 we end up eliminating it, it will be removed from the live list
989 of each basic block by reload. */
991 if (! reload_completed || frame_pointer_needed)
993 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
994 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
995 /* If they are different, also mark the hard frame pointer as live. */
996 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
997 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
1001 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
1002 /* Many architectures have a GP register even without flag_pic.
1003 Assume the pic register is not in use, or will be handled by
1004 other means, if it is not fixed. */
1005 if ((unsigned) PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
1006 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
1007 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
1010 /* Mark all global registers, and all registers used by the epilogue
1011 as being live at the end of the function since they may be
1012 referenced by our caller. */
1013 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1014 if (global_regs[i] || EPILOGUE_USES (i))
1015 SET_REGNO_REG_SET (set, i);
1017 if (HAVE_epilogue && epilogue_completed)
1019 /* Mark all call-saved registers that we actually used. */
1020 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1021 if (regs_ever_live[i] && ! LOCAL_REGNO (i)
1022 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1023 SET_REGNO_REG_SET (set, i);
1026 #ifdef EH_RETURN_DATA_REGNO
1027 /* Mark the registers that will contain data for the handler. */
1028 if (reload_completed && current_function_calls_eh_return)
1031 unsigned regno = EH_RETURN_DATA_REGNO(i);
1032 if (regno == INVALID_REGNUM)
1034 SET_REGNO_REG_SET (set, regno);
1037 #ifdef EH_RETURN_STACKADJ_RTX
1038 if ((! HAVE_epilogue || ! epilogue_completed)
1039 && current_function_calls_eh_return)
1041 rtx tmp = EH_RETURN_STACKADJ_RTX;
1042 if (tmp && REG_P (tmp))
1043 mark_reg (tmp, set);
1046 #ifdef EH_RETURN_HANDLER_RTX
1047 if ((! HAVE_epilogue || ! epilogue_completed)
1048 && current_function_calls_eh_return)
1050 rtx tmp = EH_RETURN_HANDLER_RTX;
1051 if (tmp && REG_P (tmp))
1052 mark_reg (tmp, set);
1056 /* Mark function return value. */
1057 diddle_return_value (mark_reg, set);
1060 /* Propagate global life info around the graph of basic blocks. Begin
1061 considering blocks with their corresponding bit set in BLOCKS_IN.
1062 If BLOCKS_IN is null, consider it the universal set.
1064 BLOCKS_OUT is set for every block that was changed. */
1067 calculate_global_regs_live (sbitmap blocks_in, sbitmap blocks_out, int flags)
1069 basic_block *queue, *qhead, *qtail, *qend, bb;
1070 regset tmp, new_live_at_end, invalidated_by_call;
1071 regset_head tmp_head, invalidated_by_call_head;
1072 regset_head new_live_at_end_head;
1075 /* Some passes used to forget clear aux field of basic block causing
1076 sick behavior here. */
1077 #ifdef ENABLE_CHECKING
1078 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1083 tmp = INITIALIZE_REG_SET (tmp_head);
1084 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
1085 invalidated_by_call = INITIALIZE_REG_SET (invalidated_by_call_head);
1087 /* Inconveniently, this is only readily available in hard reg set form. */
1088 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
1089 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1090 SET_REGNO_REG_SET (invalidated_by_call, i);
1092 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1093 because the `head == tail' style test for an empty queue doesn't
1094 work with a full queue. */
1095 queue = xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
1097 qhead = qend = queue + n_basic_blocks + 2;
1099 /* Queue the blocks set in the initial mask. Do this in reverse block
1100 number order so that we are more likely for the first round to do
1101 useful work. We use AUX non-null to flag that the block is queued. */
1105 if (TEST_BIT (blocks_in, bb->index))
1120 /* We clean aux when we remove the initially-enqueued bbs, but we
1121 don't enqueue ENTRY and EXIT initially, so clean them upfront and
1123 ENTRY_BLOCK_PTR->aux = EXIT_BLOCK_PTR->aux = NULL;
1126 sbitmap_zero (blocks_out);
1128 /* We work through the queue until there are no more blocks. What
1129 is live at the end of this block is precisely the union of what
1130 is live at the beginning of all its successors. So, we set its
1131 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1132 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1133 this block by walking through the instructions in this block in
1134 reverse order and updating as we go. If that changed
1135 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1136 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1138 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1139 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1140 must either be live at the end of the block, or used within the
1141 block. In the latter case, it will certainly never disappear
1142 from GLOBAL_LIVE_AT_START. In the former case, the register
1143 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1144 for one of the successor blocks. By induction, that cannot
1146 while (qhead != qtail)
1148 int rescan, changed;
1157 /* Begin by propagating live_at_start from the successor blocks. */
1158 CLEAR_REG_SET (new_live_at_end);
1161 for (e = bb->succ; e; e = e->succ_next)
1163 basic_block sb = e->dest;
1165 /* Call-clobbered registers die across exception and
1167 /* ??? Abnormal call edges ignored for the moment, as this gets
1168 confused by sibling call edges, which crashes reg-stack. */
1169 if (e->flags & EDGE_EH)
1171 bitmap_operation (tmp, sb->global_live_at_start,
1172 invalidated_by_call, BITMAP_AND_COMPL);
1173 IOR_REG_SET (new_live_at_end, tmp);
1176 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
1178 /* If a target saves one register in another (instead of on
1179 the stack) the save register will need to be live for EH. */
1180 if (e->flags & EDGE_EH)
1181 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1183 SET_REGNO_REG_SET (new_live_at_end, i);
1187 /* This might be a noreturn function that throws. And
1188 even if it isn't, getting the unwind info right helps
1190 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1192 SET_REGNO_REG_SET (new_live_at_end, i);
1195 /* The all-important stack pointer must always be live. */
1196 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
1198 /* Before reload, there are a few registers that must be forced
1199 live everywhere -- which might not already be the case for
1200 blocks within infinite loops. */
1201 if (! reload_completed)
1203 /* Any reference to any pseudo before reload is a potential
1204 reference of the frame pointer. */
1205 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
1207 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1208 /* Pseudos with argument area equivalences may require
1209 reloading via the argument pointer. */
1210 if (fixed_regs[ARG_POINTER_REGNUM])
1211 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
1214 /* Any constant, or pseudo with constant equivalences, may
1215 require reloading from memory using the pic register. */
1216 if ((unsigned) PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
1217 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
1218 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
1221 if (bb == ENTRY_BLOCK_PTR)
1223 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1227 /* On our first pass through this block, we'll go ahead and continue.
1228 Recognize first pass by local_set NULL. On subsequent passes, we
1229 get to skip out early if live_at_end wouldn't have changed. */
1231 if (bb->local_set == NULL)
1233 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1234 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1239 /* If any bits were removed from live_at_end, we'll have to
1240 rescan the block. This wouldn't be necessary if we had
1241 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1242 local_live is really dependent on live_at_end. */
1243 CLEAR_REG_SET (tmp);
1244 rescan = bitmap_operation (tmp, bb->global_live_at_end,
1245 new_live_at_end, BITMAP_AND_COMPL);
1249 /* If any of the registers in the new live_at_end set are
1250 conditionally set in this basic block, we must rescan.
1251 This is because conditional lifetimes at the end of the
1252 block do not just take the live_at_end set into account,
1253 but also the liveness at the start of each successor
1254 block. We can miss changes in those sets if we only
1255 compare the new live_at_end against the previous one. */
1256 CLEAR_REG_SET (tmp);
1257 rescan = bitmap_operation (tmp, new_live_at_end,
1258 bb->cond_local_set, BITMAP_AND);
1263 /* Find the set of changed bits. Take this opportunity
1264 to notice that this set is empty and early out. */
1265 CLEAR_REG_SET (tmp);
1266 changed = bitmap_operation (tmp, bb->global_live_at_end,
1267 new_live_at_end, BITMAP_XOR);
1271 /* If any of the changed bits overlap with local_set,
1272 we'll have to rescan the block. Detect overlap by
1273 the AND with ~local_set turning off bits. */
1274 rescan = bitmap_operation (tmp, tmp, bb->local_set,
1279 /* Let our caller know that BB changed enough to require its
1280 death notes updated. */
1282 SET_BIT (blocks_out, bb->index);
1286 /* Add to live_at_start the set of all registers in
1287 new_live_at_end that aren't in the old live_at_end. */
1289 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
1291 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1293 changed = bitmap_operation (bb->global_live_at_start,
1294 bb->global_live_at_start,
1301 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1303 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1304 into live_at_start. */
1305 propagate_block (bb, new_live_at_end, bb->local_set,
1306 bb->cond_local_set, flags);
1308 /* If live_at start didn't change, no need to go farther. */
1309 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
1312 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
1315 /* Queue all predecessors of BB so that we may re-examine
1316 their live_at_end. */
1317 for (e = bb->pred; e; e = e->pred_next)
1319 basic_block pb = e->src;
1320 if (pb->aux == NULL)
1331 FREE_REG_SET (new_live_at_end);
1332 FREE_REG_SET (invalidated_by_call);
1336 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
1338 basic_block bb = BASIC_BLOCK (i);
1339 FREE_REG_SET (bb->local_set);
1340 FREE_REG_SET (bb->cond_local_set);
1347 FREE_REG_SET (bb->local_set);
1348 FREE_REG_SET (bb->cond_local_set);
1356 /* This structure is used to pass parameters to and from the
1357 the function find_regno_partial(). It is used to pass in the
1358 register number we are looking, as well as to return any rtx
1362 unsigned regno_to_find;
1364 } find_regno_partial_param;
1367 /* Find the rtx for the reg numbers specified in 'data' if it is
1368 part of an expression which only uses part of the register. Return
1369 it in the structure passed in. */
1371 find_regno_partial (rtx *ptr, void *data)
1373 find_regno_partial_param *param = (find_regno_partial_param *)data;
1374 unsigned reg = param->regno_to_find;
1375 param->retval = NULL_RTX;
1377 if (*ptr == NULL_RTX)
1380 switch (GET_CODE (*ptr))
1384 case STRICT_LOW_PART:
1385 if (GET_CODE (XEXP (*ptr, 0)) == REG && REGNO (XEXP (*ptr, 0)) == reg)
1387 param->retval = XEXP (*ptr, 0);
1393 if (GET_CODE (SUBREG_REG (*ptr)) == REG
1394 && REGNO (SUBREG_REG (*ptr)) == reg)
1396 param->retval = SUBREG_REG (*ptr);
1408 /* Process all immediate successors of the entry block looking for pseudo
1409 registers which are live on entry. Find all of those whose first
1410 instance is a partial register reference of some kind, and initialize
1411 them to 0 after the entry block. This will prevent bit sets within
1412 registers whose value is unknown, and may contain some kind of sticky
1413 bits we don't want. */
1416 initialize_uninitialized_subregs (void)
1420 int reg, did_something = 0;
1421 find_regno_partial_param param;
1423 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
1425 basic_block bb = e->dest;
1426 regset map = bb->global_live_at_start;
1427 EXECUTE_IF_SET_IN_REG_SET (map,
1428 FIRST_PSEUDO_REGISTER, reg,
1430 int uid = REGNO_FIRST_UID (reg);
1433 /* Find an insn which mentions the register we are looking for.
1434 Its preferable to have an instance of the register's rtl since
1435 there may be various flags set which we need to duplicate.
1436 If we can't find it, its probably an automatic whose initial
1437 value doesn't matter, or hopefully something we don't care about. */
1438 for (i = get_insns (); i && INSN_UID (i) != uid; i = NEXT_INSN (i))
1442 /* Found the insn, now get the REG rtx, if we can. */
1443 param.regno_to_find = reg;
1444 for_each_rtx (&i, find_regno_partial, ¶m);
1445 if (param.retval != NULL_RTX)
1448 emit_move_insn (param.retval,
1449 CONST0_RTX (GET_MODE (param.retval)));
1450 insn = get_insns ();
1452 insert_insn_on_edge (insn, e);
1460 commit_edge_insertions ();
1461 return did_something;
1465 /* Subroutines of life analysis. */
1467 /* Allocate the permanent data structures that represent the results
1468 of life analysis. Not static since used also for stupid life analysis. */
1471 allocate_bb_life_data (void)
1475 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1477 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1478 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1481 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1485 allocate_reg_life_data (void)
1489 max_regno = max_reg_num ();
1492 reg_deaths = xcalloc (sizeof (*reg_deaths), max_regno);
1494 /* Recalculate the register space, in case it has grown. Old style
1495 vector oriented regsets would set regset_{size,bytes} here also. */
1496 allocate_reg_info (max_regno, FALSE, FALSE);
1498 /* Reset all the data we'll collect in propagate_block and its
1500 for (i = 0; i < max_regno; i++)
1504 REG_N_DEATHS (i) = 0;
1505 REG_N_CALLS_CROSSED (i) = 0;
1506 REG_LIVE_LENGTH (i) = 0;
1508 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
1512 /* Delete dead instructions for propagate_block. */
1515 propagate_block_delete_insn (rtx insn)
1517 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
1519 /* If the insn referred to a label, and that label was attached to
1520 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1521 pretty much mandatory to delete it, because the ADDR_VEC may be
1522 referencing labels that no longer exist.
1524 INSN may reference a deleted label, particularly when a jump
1525 table has been optimized into a direct jump. There's no
1526 real good way to fix up the reference to the deleted label
1527 when the label is deleted, so we just allow it here. */
1529 if (inote && GET_CODE (inote) == CODE_LABEL)
1531 rtx label = XEXP (inote, 0);
1534 /* The label may be forced if it has been put in the constant
1535 pool. If that is the only use we must discard the table
1536 jump following it, but not the label itself. */
1537 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
1538 && (next = next_nonnote_insn (label)) != NULL
1539 && GET_CODE (next) == JUMP_INSN
1540 && (GET_CODE (PATTERN (next)) == ADDR_VEC
1541 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
1543 rtx pat = PATTERN (next);
1544 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
1545 int len = XVECLEN (pat, diff_vec_p);
1548 for (i = 0; i < len; i++)
1549 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
1551 delete_insn_and_edges (next);
1556 delete_insn_and_edges (insn);
1560 /* Delete dead libcalls for propagate_block. Return the insn
1561 before the libcall. */
1564 propagate_block_delete_libcall (rtx insn, rtx note)
1566 rtx first = XEXP (note, 0);
1567 rtx before = PREV_INSN (first);
1569 delete_insn_chain_and_edges (first, insn);
1574 /* Update the life-status of regs for one insn. Return the previous insn. */
1577 propagate_one_insn (struct propagate_block_info *pbi, rtx insn)
1579 rtx prev = PREV_INSN (insn);
1580 int flags = pbi->flags;
1581 int insn_is_dead = 0;
1582 int libcall_is_dead = 0;
1586 if (! INSN_P (insn))
1589 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1590 if (flags & PROP_SCAN_DEAD_CODE)
1592 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
1593 libcall_is_dead = (insn_is_dead && note != 0
1594 && libcall_dead_p (pbi, note, insn));
1597 /* If an instruction consists of just dead store(s) on final pass,
1599 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
1601 /* If we're trying to delete a prologue or epilogue instruction
1602 that isn't flagged as possibly being dead, something is wrong.
1603 But if we are keeping the stack pointer depressed, we might well
1604 be deleting insns that are used to compute the amount to update
1605 it by, so they are fine. */
1606 if (reload_completed
1607 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1608 && (TYPE_RETURNS_STACK_DEPRESSED
1609 (TREE_TYPE (current_function_decl))))
1610 && (((HAVE_epilogue || HAVE_prologue)
1611 && prologue_epilogue_contains (insn))
1612 || (HAVE_sibcall_epilogue
1613 && sibcall_epilogue_contains (insn)))
1614 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
1615 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn);
1617 /* Record sets. Do this even for dead instructions, since they
1618 would have killed the values if they hadn't been deleted. */
1619 mark_set_regs (pbi, PATTERN (insn), insn);
1621 /* CC0 is now known to be dead. Either this insn used it,
1622 in which case it doesn't anymore, or clobbered it,
1623 so the next insn can't use it. */
1626 if (libcall_is_dead)
1627 prev = propagate_block_delete_libcall ( insn, note);
1631 /* If INSN contains a RETVAL note and is dead, but the libcall
1632 as a whole is not dead, then we want to remove INSN, but
1633 not the whole libcall sequence.
1635 However, we need to also remove the dangling REG_LIBCALL
1636 note so that we do not have mis-matched LIBCALL/RETVAL
1637 notes. In theory we could find a new location for the
1638 REG_RETVAL note, but it hardly seems worth the effort.
1640 NOTE at this point will be the RETVAL note if it exists. */
1646 = find_reg_note (XEXP (note, 0), REG_LIBCALL, NULL_RTX);
1647 remove_note (XEXP (note, 0), libcall_note);
1650 /* Similarly if INSN contains a LIBCALL note, remove the
1651 dangling REG_RETVAL note. */
1652 note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
1658 = find_reg_note (XEXP (note, 0), REG_RETVAL, NULL_RTX);
1659 remove_note (XEXP (note, 0), retval_note);
1662 /* Now delete INSN. */
1663 propagate_block_delete_insn (insn);
1669 /* See if this is an increment or decrement that can be merged into
1670 a following memory address. */
1673 rtx x = single_set (insn);
1675 /* Does this instruction increment or decrement a register? */
1676 if ((flags & PROP_AUTOINC)
1678 && GET_CODE (SET_DEST (x)) == REG
1679 && (GET_CODE (SET_SRC (x)) == PLUS
1680 || GET_CODE (SET_SRC (x)) == MINUS)
1681 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1682 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1683 /* Ok, look for a following memory ref we can combine with.
1684 If one is found, change the memory ref to a PRE_INC
1685 or PRE_DEC, cancel this insn, and return 1.
1686 Return 0 if nothing has been done. */
1687 && try_pre_increment_1 (pbi, insn))
1690 #endif /* AUTO_INC_DEC */
1692 CLEAR_REG_SET (pbi->new_set);
1694 /* If this is not the final pass, and this insn is copying the value of
1695 a library call and it's dead, don't scan the insns that perform the
1696 library call, so that the call's arguments are not marked live. */
1697 if (libcall_is_dead)
1699 /* Record the death of the dest reg. */
1700 mark_set_regs (pbi, PATTERN (insn), insn);
1702 insn = XEXP (note, 0);
1703 return PREV_INSN (insn);
1705 else if (GET_CODE (PATTERN (insn)) == SET
1706 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1707 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1708 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1709 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1710 /* We have an insn to pop a constant amount off the stack.
1711 (Such insns use PLUS regardless of the direction of the stack,
1712 and any insn to adjust the stack by a constant is always a pop.)
1713 These insns, if not dead stores, have no effect on life, though
1714 they do have an effect on the memory stores we are tracking. */
1715 invalidate_mems_from_set (pbi, stack_pointer_rtx);
1719 /* Any regs live at the time of a call instruction must not go
1720 in a register clobbered by calls. Find all regs now live and
1721 record this for them. */
1723 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
1724 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
1725 { REG_N_CALLS_CROSSED (i)++; });
1727 /* Record sets. Do this even for dead instructions, since they
1728 would have killed the values if they hadn't been deleted. */
1729 mark_set_regs (pbi, PATTERN (insn), insn);
1731 if (GET_CODE (insn) == CALL_INSN)
1739 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1740 cond = COND_EXEC_TEST (PATTERN (insn));
1742 /* Non-constant calls clobber memory, constant calls do not
1743 clobber memory, though they may clobber outgoing arguments
1745 if (! CONST_OR_PURE_CALL_P (insn))
1747 free_EXPR_LIST_list (&pbi->mem_set_list);
1748 pbi->mem_set_list_len = 0;
1751 invalidate_mems_from_set (pbi, stack_pointer_rtx);
1753 /* There may be extra registers to be clobbered. */
1754 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1756 note = XEXP (note, 1))
1757 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
1758 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
1759 cond, insn, pbi->flags);
1761 /* Calls change all call-used and global registers; sibcalls do not
1762 clobber anything that must be preserved at end-of-function,
1763 except for return values. */
1765 sibcall_p = SIBLING_CALL_P (insn);
1766 live_at_end = EXIT_BLOCK_PTR->global_live_at_start;
1767 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1768 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i)
1770 && REGNO_REG_SET_P (live_at_end, i)
1771 && ! refers_to_regno_p (i, i+1,
1772 current_function_return_rtx,
1775 /* We do not want REG_UNUSED notes for these registers. */
1776 mark_set_1 (pbi, CLOBBER, regno_reg_rtx[i], cond, insn,
1777 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
1781 /* If an insn doesn't use CC0, it becomes dead since we assume
1782 that every insn clobbers it. So show it dead here;
1783 mark_used_regs will set it live if it is referenced. */
1788 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
1789 if ((flags & PROP_EQUAL_NOTES)
1790 && ((note = find_reg_note (insn, REG_EQUAL, NULL_RTX))
1791 || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX))))
1792 mark_used_regs (pbi, XEXP (note, 0), NULL_RTX, insn);
1794 /* Sometimes we may have inserted something before INSN (such as a move)
1795 when we make an auto-inc. So ensure we will scan those insns. */
1797 prev = PREV_INSN (insn);
1800 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1806 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1807 cond = COND_EXEC_TEST (PATTERN (insn));
1809 /* Calls use their arguments, and may clobber memory which
1810 address involves some register. */
1811 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1813 note = XEXP (note, 1))
1814 /* We find USE or CLOBBER entities in a FUNCTION_USAGE list: both
1815 of which mark_used_regs knows how to handle. */
1816 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0), cond, insn);
1818 /* The stack ptr is used (honorarily) by a CALL insn. */
1819 if ((flags & PROP_REG_INFO)
1820 && !REGNO_REG_SET_P (pbi->reg_live, STACK_POINTER_REGNUM))
1821 reg_deaths[STACK_POINTER_REGNUM] = pbi->insn_num;
1822 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
1824 /* Calls may also reference any of the global registers,
1825 so they are made live. */
1826 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1828 mark_used_reg (pbi, regno_reg_rtx[i], cond, insn);
1837 /* Initialize a propagate_block_info struct for public consumption.
1838 Note that the structure itself is opaque to this file, but that
1839 the user can use the regsets provided here. */
1841 struct propagate_block_info *
1842 init_propagate_block_info (basic_block bb, regset live, regset local_set,
1843 regset cond_local_set, int flags)
1845 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
1848 pbi->reg_live = live;
1849 pbi->mem_set_list = NULL_RTX;
1850 pbi->mem_set_list_len = 0;
1851 pbi->local_set = local_set;
1852 pbi->cond_local_set = cond_local_set;
1857 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
1858 pbi->reg_next_use = xcalloc (max_reg_num (), sizeof (rtx));
1860 pbi->reg_next_use = NULL;
1862 pbi->new_set = BITMAP_XMALLOC ();
1864 #ifdef HAVE_conditional_execution
1865 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
1866 free_reg_cond_life_info);
1867 pbi->reg_cond_reg = BITMAP_XMALLOC ();
1869 /* If this block ends in a conditional branch, for each register
1870 live from one side of the branch and not the other, record the
1871 register as conditionally dead. */
1872 if (GET_CODE (BB_END (bb)) == JUMP_INSN
1873 && any_condjump_p (BB_END (bb)))
1875 regset_head diff_head;
1876 regset diff = INITIALIZE_REG_SET (diff_head);
1877 basic_block bb_true, bb_false;
1880 /* Identify the successor blocks. */
1881 bb_true = bb->succ->dest;
1882 if (bb->succ->succ_next != NULL)
1884 bb_false = bb->succ->succ_next->dest;
1886 if (bb->succ->flags & EDGE_FALLTHRU)
1888 basic_block t = bb_false;
1892 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
1897 /* This can happen with a conditional jump to the next insn. */
1898 if (JUMP_LABEL (BB_END (bb)) != BB_HEAD (bb_true))
1901 /* Simplest way to do nothing. */
1905 /* Compute which register lead different lives in the successors. */
1906 if (bitmap_operation (diff, bb_true->global_live_at_start,
1907 bb_false->global_live_at_start, BITMAP_XOR))
1909 /* Extract the condition from the branch. */
1910 rtx set_src = SET_SRC (pc_set (BB_END (bb)));
1911 rtx cond_true = XEXP (set_src, 0);
1912 rtx reg = XEXP (cond_true, 0);
1914 if (GET_CODE (reg) == SUBREG)
1915 reg = SUBREG_REG (reg);
1917 /* We can only track conditional lifetimes if the condition is
1918 in the form of a comparison of a register against zero.
1919 If the condition is more complex than that, then it is safe
1920 not to record any information. */
1921 if (GET_CODE (reg) == REG
1922 && XEXP (cond_true, 1) == const0_rtx)
1925 = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
1926 GET_MODE (cond_true), XEXP (cond_true, 0),
1927 XEXP (cond_true, 1));
1928 if (GET_CODE (XEXP (set_src, 1)) == PC)
1931 cond_false = cond_true;
1935 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
1937 /* For each such register, mark it conditionally dead. */
1938 EXECUTE_IF_SET_IN_REG_SET
1941 struct reg_cond_life_info *rcli;
1944 rcli = xmalloc (sizeof (*rcli));
1946 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
1950 rcli->condition = cond;
1951 rcli->stores = const0_rtx;
1952 rcli->orig_condition = cond;
1954 splay_tree_insert (pbi->reg_cond_dead, i,
1955 (splay_tree_value) rcli);
1960 FREE_REG_SET (diff);
1964 /* If this block has no successors, any stores to the frame that aren't
1965 used later in the block are dead. So make a pass over the block
1966 recording any such that are made and show them dead at the end. We do
1967 a very conservative and simple job here. */
1969 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1970 && (TYPE_RETURNS_STACK_DEPRESSED
1971 (TREE_TYPE (current_function_decl))))
1972 && (flags & PROP_SCAN_DEAD_STORES)
1973 && (bb->succ == NULL
1974 || (bb->succ->succ_next == NULL
1975 && bb->succ->dest == EXIT_BLOCK_PTR
1976 && ! current_function_calls_eh_return)))
1979 for (insn = BB_END (bb); insn != BB_HEAD (bb); insn = PREV_INSN (insn))
1980 if (GET_CODE (insn) == INSN
1981 && (set = single_set (insn))
1982 && GET_CODE (SET_DEST (set)) == MEM)
1984 rtx mem = SET_DEST (set);
1985 rtx canon_mem = canon_rtx (mem);
1987 if (XEXP (canon_mem, 0) == frame_pointer_rtx
1988 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
1989 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
1990 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
1991 add_to_mem_set_list (pbi, canon_mem);
1998 /* Release a propagate_block_info struct. */
2001 free_propagate_block_info (struct propagate_block_info *pbi)
2003 free_EXPR_LIST_list (&pbi->mem_set_list);
2005 BITMAP_XFREE (pbi->new_set);
2007 #ifdef HAVE_conditional_execution
2008 splay_tree_delete (pbi->reg_cond_dead);
2009 BITMAP_XFREE (pbi->reg_cond_reg);
2012 if (pbi->flags & PROP_REG_INFO)
2014 int num = pbi->insn_num;
2017 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
2018 { REG_LIVE_LENGTH (i) += num - reg_deaths[i];
2022 if (pbi->reg_next_use)
2023 free (pbi->reg_next_use);
2028 /* Compute the registers live at the beginning of a basic block BB from
2029 those live at the end.
2031 When called, REG_LIVE contains those live at the end. On return, it
2032 contains those live at the beginning.
2034 LOCAL_SET, if non-null, will be set with all registers killed
2035 unconditionally by this basic block.
2036 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
2037 killed conditionally by this basic block. If there is any unconditional
2038 set of a register, then the corresponding bit will be set in LOCAL_SET
2039 and cleared in COND_LOCAL_SET.
2040 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
2041 case, the resulting set will be equal to the union of the two sets that
2042 would otherwise be computed.
2044 Return nonzero if an INSN is deleted (i.e. by dead code removal). */
2047 propagate_block (basic_block bb, regset live, regset local_set,
2048 regset cond_local_set, int flags)
2050 struct propagate_block_info *pbi;
2054 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
2056 if (flags & PROP_REG_INFO)
2060 /* Process the regs live at the end of the block.
2061 Mark them as not local to any one basic block. */
2062 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
2063 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
2066 /* Scan the block an insn at a time from end to beginning. */
2069 for (insn = BB_END (bb); ; insn = prev)
2071 /* If this is a call to `setjmp' et al, warn if any
2072 non-volatile datum is live. */
2073 if ((flags & PROP_REG_INFO)
2074 && GET_CODE (insn) == CALL_INSN
2075 && find_reg_note (insn, REG_SETJMP, NULL))
2076 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
2078 prev = propagate_one_insn (pbi, insn);
2080 changed |= insn != get_insns ();
2082 changed |= NEXT_INSN (prev) != insn;
2084 if (insn == BB_HEAD (bb))
2088 free_propagate_block_info (pbi);
2093 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2094 (SET expressions whose destinations are registers dead after the insn).
2095 NEEDED is the regset that says which regs are alive after the insn.
2097 Unless CALL_OK is nonzero, an insn is needed if it contains a CALL.
2099 If X is the entire body of an insn, NOTES contains the reg notes
2100 pertaining to the insn. */
2103 insn_dead_p (struct propagate_block_info *pbi, rtx x, int call_ok,
2104 rtx notes ATTRIBUTE_UNUSED)
2106 enum rtx_code code = GET_CODE (x);
2108 /* Don't eliminate insns that may trap. */
2109 if (flag_non_call_exceptions && may_trap_p (x))
2113 /* As flow is invoked after combine, we must take existing AUTO_INC
2114 expressions into account. */
2115 for (; notes; notes = XEXP (notes, 1))
2117 if (REG_NOTE_KIND (notes) == REG_INC)
2119 int regno = REGNO (XEXP (notes, 0));
2121 /* Don't delete insns to set global regs. */
2122 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2123 || REGNO_REG_SET_P (pbi->reg_live, regno))
2129 /* If setting something that's a reg or part of one,
2130 see if that register's altered value will be live. */
2134 rtx r = SET_DEST (x);
2137 if (GET_CODE (r) == CC0)
2138 return ! pbi->cc0_live;
2141 /* A SET that is a subroutine call cannot be dead. */
2142 if (GET_CODE (SET_SRC (x)) == CALL)
2148 /* Don't eliminate loads from volatile memory or volatile asms. */
2149 else if (volatile_refs_p (SET_SRC (x)))
2152 if (GET_CODE (r) == MEM)
2156 if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode)
2159 canon_r = canon_rtx (r);
2161 /* Walk the set of memory locations we are currently tracking
2162 and see if one is an identical match to this memory location.
2163 If so, this memory write is dead (remember, we're walking
2164 backwards from the end of the block to the start). Since
2165 rtx_equal_p does not check the alias set or flags, we also
2166 must have the potential for them to conflict (anti_dependence). */
2167 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
2168 if (unchanging_anti_dependence (r, XEXP (temp, 0)))
2170 rtx mem = XEXP (temp, 0);
2172 if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0))
2173 && (GET_MODE_SIZE (GET_MODE (canon_r))
2174 <= GET_MODE_SIZE (GET_MODE (mem))))
2178 /* Check if memory reference matches an auto increment. Only
2179 post increment/decrement or modify are valid. */
2180 if (GET_MODE (mem) == GET_MODE (r)
2181 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
2182 || GET_CODE (XEXP (mem, 0)) == POST_INC
2183 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
2184 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
2185 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
2192 while (GET_CODE (r) == SUBREG
2193 || GET_CODE (r) == STRICT_LOW_PART
2194 || GET_CODE (r) == ZERO_EXTRACT)
2197 if (GET_CODE (r) == REG)
2199 int regno = REGNO (r);
2202 if (REGNO_REG_SET_P (pbi->reg_live, regno))
2205 /* If this is a hard register, verify that subsequent
2206 words are not needed. */
2207 if (regno < FIRST_PSEUDO_REGISTER)
2209 int n = hard_regno_nregs[regno][GET_MODE (r)];
2212 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
2216 /* Don't delete insns to set global regs. */
2217 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2220 /* Make sure insns to set the stack pointer aren't deleted. */
2221 if (regno == STACK_POINTER_REGNUM)
2224 /* ??? These bits might be redundant with the force live bits
2225 in calculate_global_regs_live. We would delete from
2226 sequential sets; whether this actually affects real code
2227 for anything but the stack pointer I don't know. */
2228 /* Make sure insns to set the frame pointer aren't deleted. */
2229 if (regno == FRAME_POINTER_REGNUM
2230 && (! reload_completed || frame_pointer_needed))
2232 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2233 if (regno == HARD_FRAME_POINTER_REGNUM
2234 && (! reload_completed || frame_pointer_needed))
2238 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2239 /* Make sure insns to set arg pointer are never deleted
2240 (if the arg pointer isn't fixed, there will be a USE
2241 for it, so we can treat it normally). */
2242 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2246 /* Otherwise, the set is dead. */
2252 /* If performing several activities, insn is dead if each activity
2253 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2254 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2256 else if (code == PARALLEL)
2258 int i = XVECLEN (x, 0);
2260 for (i--; i >= 0; i--)
2261 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
2262 && GET_CODE (XVECEXP (x, 0, i)) != USE
2263 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
2269 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2270 is not necessarily true for hard registers until after reload. */
2271 else if (code == CLOBBER)
2273 if (GET_CODE (XEXP (x, 0)) == REG
2274 && (REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
2275 || reload_completed)
2276 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
2280 /* ??? A base USE is a historical relic. It ought not be needed anymore.
2281 Instances where it is still used are either (1) temporary and the USE
2282 escaped the pass, (2) cruft and the USE need not be emitted anymore,
2283 or (3) hiding bugs elsewhere that are not properly representing data
2289 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2290 return 1 if the entire library call is dead.
2291 This is true if INSN copies a register (hard or pseudo)
2292 and if the hard return reg of the call insn is dead.
2293 (The caller should have tested the destination of the SET inside
2294 INSN already for death.)
2296 If this insn doesn't just copy a register, then we don't
2297 have an ordinary libcall. In that case, cse could not have
2298 managed to substitute the source for the dest later on,
2299 so we can assume the libcall is dead.
2301 PBI is the block info giving pseudoregs live before this insn.
2302 NOTE is the REG_RETVAL note of the insn. */
2305 libcall_dead_p (struct propagate_block_info *pbi, rtx note, rtx insn)
2307 rtx x = single_set (insn);
2311 rtx r = SET_SRC (x);
2313 if (GET_CODE (r) == REG)
2315 rtx call = XEXP (note, 0);
2319 /* Find the call insn. */
2320 while (call != insn && GET_CODE (call) != CALL_INSN)
2321 call = NEXT_INSN (call);
2323 /* If there is none, do nothing special,
2324 since ordinary death handling can understand these insns. */
2328 /* See if the hard reg holding the value is dead.
2329 If this is a PARALLEL, find the call within it. */
2330 call_pat = PATTERN (call);
2331 if (GET_CODE (call_pat) == PARALLEL)
2333 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
2334 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
2335 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
2338 /* This may be a library call that is returning a value
2339 via invisible pointer. Do nothing special, since
2340 ordinary death handling can understand these insns. */
2344 call_pat = XVECEXP (call_pat, 0, i);
2347 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
2353 /* Return 1 if register REGNO was used before it was set, i.e. if it is
2354 live at function entry. Don't count global register variables, variables
2355 in registers that can be used for function arg passing, or variables in
2356 fixed hard registers. */
2359 regno_uninitialized (unsigned int regno)
2361 if (n_basic_blocks == 0
2362 || (regno < FIRST_PSEUDO_REGISTER
2363 && (global_regs[regno]
2364 || fixed_regs[regno]
2365 || FUNCTION_ARG_REGNO_P (regno))))
2368 return REGNO_REG_SET_P (ENTRY_BLOCK_PTR->global_live_at_end, regno);
2371 /* 1 if register REGNO was alive at a place where `setjmp' was called
2372 and was set more than once or is an argument.
2373 Such regs may be clobbered by `longjmp'. */
2376 regno_clobbered_at_setjmp (int regno)
2378 if (n_basic_blocks == 0)
2381 return ((REG_N_SETS (regno) > 1
2382 || REGNO_REG_SET_P (ENTRY_BLOCK_PTR->global_live_at_end, regno))
2383 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
2386 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2387 maximal list size; look for overlaps in mode and select the largest. */
2389 add_to_mem_set_list (struct propagate_block_info *pbi, rtx mem)
2393 /* We don't know how large a BLKmode store is, so we must not
2394 take them into consideration. */
2395 if (GET_MODE (mem) == BLKmode)
2398 for (i = pbi->mem_set_list; i ; i = XEXP (i, 1))
2400 rtx e = XEXP (i, 0);
2401 if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0)))
2403 if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e)))
2406 /* If we must store a copy of the mem, we can just modify
2407 the mode of the stored copy. */
2408 if (pbi->flags & PROP_AUTOINC)
2409 PUT_MODE (e, GET_MODE (mem));
2418 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN)
2421 /* Store a copy of mem, otherwise the address may be
2422 scrogged by find_auto_inc. */
2423 if (pbi->flags & PROP_AUTOINC)
2424 mem = shallow_copy_rtx (mem);
2426 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
2427 pbi->mem_set_list_len++;
2431 /* INSN references memory, possibly using autoincrement addressing modes.
2432 Find any entries on the mem_set_list that need to be invalidated due
2433 to an address change. */
2436 invalidate_mems_from_autoinc (rtx *px, void *data)
2439 struct propagate_block_info *pbi = data;
2441 if (GET_RTX_CLASS (GET_CODE (x)) == 'a')
2443 invalidate_mems_from_set (pbi, XEXP (x, 0));
2450 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2453 invalidate_mems_from_set (struct propagate_block_info *pbi, rtx exp)
2455 rtx temp = pbi->mem_set_list;
2456 rtx prev = NULL_RTX;
2461 next = XEXP (temp, 1);
2462 if (reg_overlap_mentioned_p (exp, XEXP (temp, 0)))
2464 /* Splice this entry out of the list. */
2466 XEXP (prev, 1) = next;
2468 pbi->mem_set_list = next;
2469 free_EXPR_LIST_node (temp);
2470 pbi->mem_set_list_len--;
2478 /* Process the registers that are set within X. Their bits are set to
2479 1 in the regset DEAD, because they are dead prior to this insn.
2481 If INSN is nonzero, it is the insn being processed.
2483 FLAGS is the set of operations to perform. */
2486 mark_set_regs (struct propagate_block_info *pbi, rtx x, rtx insn)
2488 rtx cond = NULL_RTX;
2491 int flags = pbi->flags;
2494 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2496 if (REG_NOTE_KIND (link) == REG_INC)
2497 mark_set_1 (pbi, SET, XEXP (link, 0),
2498 (GET_CODE (x) == COND_EXEC
2499 ? COND_EXEC_TEST (x) : NULL_RTX),
2503 switch (code = GET_CODE (x))
2506 if (GET_CODE (XEXP (x, 1)) == ASM_OPERANDS)
2507 flags |= PROP_ASM_SCAN;
2510 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, flags);
2514 cond = COND_EXEC_TEST (x);
2515 x = COND_EXEC_CODE (x);
2522 /* We must scan forwards. If we have an asm, we need to set
2523 the PROP_ASM_SCAN flag before scanning the clobbers. */
2524 for (i = 0; i < XVECLEN (x, 0); i++)
2526 rtx sub = XVECEXP (x, 0, i);
2527 switch (code = GET_CODE (sub))
2530 if (cond != NULL_RTX)
2533 cond = COND_EXEC_TEST (sub);
2534 sub = COND_EXEC_CODE (sub);
2535 if (GET_CODE (sub) == SET)
2537 if (GET_CODE (sub) == CLOBBER)
2543 if (GET_CODE (XEXP (sub, 1)) == ASM_OPERANDS)
2544 flags |= PROP_ASM_SCAN;
2548 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, flags);
2552 flags |= PROP_ASM_SCAN;
2567 /* Process a single set, which appears in INSN. REG (which may not
2568 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2569 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2570 If the set is conditional (because it appear in a COND_EXEC), COND
2571 will be the condition. */
2574 mark_set_1 (struct propagate_block_info *pbi, enum rtx_code code, rtx reg, rtx cond, rtx insn, int flags)
2576 int regno_first = -1, regno_last = -1;
2577 unsigned long not_dead = 0;
2580 /* Modifying just one hardware register of a multi-reg value or just a
2581 byte field of a register does not mean the value from before this insn
2582 is now dead. Of course, if it was dead after it's unused now. */
2584 switch (GET_CODE (reg))
2587 /* Some targets place small structures in registers for return values of
2588 functions. We have to detect this case specially here to get correct
2589 flow information. */
2590 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
2591 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
2592 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
2598 case STRICT_LOW_PART:
2599 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2601 reg = XEXP (reg, 0);
2602 while (GET_CODE (reg) == SUBREG
2603 || GET_CODE (reg) == ZERO_EXTRACT
2604 || GET_CODE (reg) == SIGN_EXTRACT
2605 || GET_CODE (reg) == STRICT_LOW_PART);
2606 if (GET_CODE (reg) == MEM)
2608 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
2612 regno_last = regno_first = REGNO (reg);
2613 if (regno_first < FIRST_PSEUDO_REGISTER)
2614 regno_last += hard_regno_nregs[regno_first][GET_MODE (reg)] - 1;
2618 if (GET_CODE (SUBREG_REG (reg)) == REG)
2620 enum machine_mode outer_mode = GET_MODE (reg);
2621 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
2623 /* Identify the range of registers affected. This is moderately
2624 tricky for hard registers. See alter_subreg. */
2626 regno_last = regno_first = REGNO (SUBREG_REG (reg));
2627 if (regno_first < FIRST_PSEUDO_REGISTER)
2629 regno_first += subreg_regno_offset (regno_first, inner_mode,
2632 regno_last = (regno_first
2633 + hard_regno_nregs[regno_first][outer_mode] - 1);
2635 /* Since we've just adjusted the register number ranges, make
2636 sure REG matches. Otherwise some_was_live will be clear
2637 when it shouldn't have been, and we'll create incorrect
2638 REG_UNUSED notes. */
2639 reg = gen_rtx_REG (outer_mode, regno_first);
2643 /* If the number of words in the subreg is less than the number
2644 of words in the full register, we have a well-defined partial
2645 set. Otherwise the high bits are undefined.
2647 This is only really applicable to pseudos, since we just took
2648 care of multi-word hard registers. */
2649 if (((GET_MODE_SIZE (outer_mode)
2650 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
2651 < ((GET_MODE_SIZE (inner_mode)
2652 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
2653 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
2656 reg = SUBREG_REG (reg);
2660 reg = SUBREG_REG (reg);
2667 /* If this set is a MEM, then it kills any aliased writes.
2668 If this set is a REG, then it kills any MEMs which use the reg. */
2669 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
2671 if (GET_CODE (reg) == REG)
2672 invalidate_mems_from_set (pbi, reg);
2674 /* If the memory reference had embedded side effects (autoincrement
2675 address modes. Then we may need to kill some entries on the
2677 if (insn && GET_CODE (reg) == MEM)
2678 for_each_rtx (&PATTERN (insn), invalidate_mems_from_autoinc, pbi);
2680 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
2681 /* ??? With more effort we could track conditional memory life. */
2683 add_to_mem_set_list (pbi, canon_rtx (reg));
2686 if (GET_CODE (reg) == REG
2687 && ! (regno_first == FRAME_POINTER_REGNUM
2688 && (! reload_completed || frame_pointer_needed))
2689 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2690 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
2691 && (! reload_completed || frame_pointer_needed))
2693 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2694 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
2698 int some_was_live = 0, some_was_dead = 0;
2700 for (i = regno_first; i <= regno_last; ++i)
2702 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
2705 /* Order of the set operation matters here since both
2706 sets may be the same. */
2707 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
2708 if (cond != NULL_RTX
2709 && ! REGNO_REG_SET_P (pbi->local_set, i))
2710 SET_REGNO_REG_SET (pbi->cond_local_set, i);
2712 SET_REGNO_REG_SET (pbi->local_set, i);
2714 if (code != CLOBBER)
2715 SET_REGNO_REG_SET (pbi->new_set, i);
2717 some_was_live |= needed_regno;
2718 some_was_dead |= ! needed_regno;
2721 #ifdef HAVE_conditional_execution
2722 /* Consider conditional death in deciding that the register needs
2724 if (some_was_live && ! not_dead
2725 /* The stack pointer is never dead. Well, not strictly true,
2726 but it's very difficult to tell from here. Hopefully
2727 combine_stack_adjustments will fix up the most egregious
2729 && regno_first != STACK_POINTER_REGNUM)
2731 for (i = regno_first; i <= regno_last; ++i)
2732 if (! mark_regno_cond_dead (pbi, i, cond))
2733 not_dead |= ((unsigned long) 1) << (i - regno_first);
2737 /* Additional data to record if this is the final pass. */
2738 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
2739 | PROP_DEATH_NOTES | PROP_AUTOINC))
2742 int blocknum = pbi->bb->index;
2745 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2747 y = pbi->reg_next_use[regno_first];
2749 /* The next use is no longer next, since a store intervenes. */
2750 for (i = regno_first; i <= regno_last; ++i)
2751 pbi->reg_next_use[i] = 0;
2754 if (flags & PROP_REG_INFO)
2756 for (i = regno_first; i <= regno_last; ++i)
2758 /* Count (weighted) references, stores, etc. This counts a
2759 register twice if it is modified, but that is correct. */
2760 REG_N_SETS (i) += 1;
2761 REG_N_REFS (i) += 1;
2762 REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb);
2764 /* The insns where a reg is live are normally counted
2765 elsewhere, but we want the count to include the insn
2766 where the reg is set, and the normal counting mechanism
2767 would not count it. */
2768 REG_LIVE_LENGTH (i) += 1;
2771 /* If this is a hard reg, record this function uses the reg. */
2772 if (regno_first < FIRST_PSEUDO_REGISTER)
2774 for (i = regno_first; i <= regno_last; i++)
2775 regs_ever_live[i] = 1;
2776 if (flags & PROP_ASM_SCAN)
2777 for (i = regno_first; i <= regno_last; i++)
2778 regs_asm_clobbered[i] = 1;
2782 /* Keep track of which basic blocks each reg appears in. */
2783 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
2784 REG_BASIC_BLOCK (regno_first) = blocknum;
2785 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
2786 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
2790 if (! some_was_dead)
2792 if (flags & PROP_LOG_LINKS)
2794 /* Make a logical link from the next following insn
2795 that uses this register, back to this insn.
2796 The following insns have already been processed.
2798 We don't build a LOG_LINK for hard registers containing
2799 in ASM_OPERANDs. If these registers get replaced,
2800 we might wind up changing the semantics of the insn,
2801 even if reload can make what appear to be valid
2802 assignments later. */
2803 if (y && (BLOCK_NUM (y) == blocknum)
2804 && (regno_first >= FIRST_PSEUDO_REGISTER
2805 || asm_noperands (PATTERN (y)) < 0))
2806 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
2811 else if (! some_was_live)
2813 if (flags & PROP_REG_INFO)
2814 REG_N_DEATHS (regno_first) += 1;
2816 if (flags & PROP_DEATH_NOTES)
2818 /* Note that dead stores have already been deleted
2819 when possible. If we get here, we have found a
2820 dead store that cannot be eliminated (because the
2821 same insn does something useful). Indicate this
2822 by marking the reg being set as dying here. */
2824 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2829 if (flags & PROP_DEATH_NOTES)
2831 /* This is a case where we have a multi-word hard register
2832 and some, but not all, of the words of the register are
2833 needed in subsequent insns. Write REG_UNUSED notes
2834 for those parts that were not needed. This case should
2837 for (i = regno_first; i <= regno_last; ++i)
2838 if (! REGNO_REG_SET_P (pbi->reg_live, i))
2840 = alloc_EXPR_LIST (REG_UNUSED,
2847 /* Mark the register as being dead. */
2849 /* The stack pointer is never dead. Well, not strictly true,
2850 but it's very difficult to tell from here. Hopefully
2851 combine_stack_adjustments will fix up the most egregious
2853 && regno_first != STACK_POINTER_REGNUM)
2855 for (i = regno_first; i <= regno_last; ++i)
2856 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
2858 if ((pbi->flags & PROP_REG_INFO)
2859 && REGNO_REG_SET_P (pbi->reg_live, i))
2861 REG_LIVE_LENGTH (i) += pbi->insn_num - reg_deaths[i];
2864 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
2868 else if (GET_CODE (reg) == REG)
2870 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2871 pbi->reg_next_use[regno_first] = 0;
2873 if ((flags & PROP_REG_INFO) != 0
2874 && (flags & PROP_ASM_SCAN) != 0
2875 && regno_first < FIRST_PSEUDO_REGISTER)
2877 for (i = regno_first; i <= regno_last; i++)
2878 regs_asm_clobbered[i] = 1;
2882 /* If this is the last pass and this is a SCRATCH, show it will be dying
2883 here and count it. */
2884 else if (GET_CODE (reg) == SCRATCH)
2886 if (flags & PROP_DEATH_NOTES)
2888 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2892 #ifdef HAVE_conditional_execution
2893 /* Mark REGNO conditionally dead.
2894 Return true if the register is now unconditionally dead. */
2897 mark_regno_cond_dead (struct propagate_block_info *pbi, int regno, rtx cond)
2899 /* If this is a store to a predicate register, the value of the
2900 predicate is changing, we don't know that the predicate as seen
2901 before is the same as that seen after. Flush all dependent
2902 conditions from reg_cond_dead. This will make all such
2903 conditionally live registers unconditionally live. */
2904 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
2905 flush_reg_cond_reg (pbi, regno);
2907 /* If this is an unconditional store, remove any conditional
2908 life that may have existed. */
2909 if (cond == NULL_RTX)
2910 splay_tree_remove (pbi->reg_cond_dead, regno);
2913 splay_tree_node node;
2914 struct reg_cond_life_info *rcli;
2917 /* Otherwise this is a conditional set. Record that fact.
2918 It may have been conditionally used, or there may be a
2919 subsequent set with a complimentary condition. */
2921 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
2924 /* The register was unconditionally live previously.
2925 Record the current condition as the condition under
2926 which it is dead. */
2927 rcli = xmalloc (sizeof (*rcli));
2928 rcli->condition = cond;
2929 rcli->stores = cond;
2930 rcli->orig_condition = const0_rtx;
2931 splay_tree_insert (pbi->reg_cond_dead, regno,
2932 (splay_tree_value) rcli);
2934 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2936 /* Not unconditionally dead. */
2941 /* The register was conditionally live previously.
2942 Add the new condition to the old. */
2943 rcli = (struct reg_cond_life_info *) node->value;
2944 ncond = rcli->condition;
2945 ncond = ior_reg_cond (ncond, cond, 1);
2946 if (rcli->stores == const0_rtx)
2947 rcli->stores = cond;
2948 else if (rcli->stores != const1_rtx)
2949 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
2951 /* If the register is now unconditionally dead, remove the entry
2952 in the splay_tree. A register is unconditionally dead if the
2953 dead condition ncond is true. A register is also unconditionally
2954 dead if the sum of all conditional stores is an unconditional
2955 store (stores is true), and the dead condition is identically the
2956 same as the original dead condition initialized at the end of
2957 the block. This is a pointer compare, not an rtx_equal_p
2959 if (ncond == const1_rtx
2960 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
2961 splay_tree_remove (pbi->reg_cond_dead, regno);
2964 rcli->condition = ncond;
2966 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2968 /* Not unconditionally dead. */
2977 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2980 free_reg_cond_life_info (splay_tree_value value)
2982 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
2986 /* Helper function for flush_reg_cond_reg. */
2989 flush_reg_cond_reg_1 (splay_tree_node node, void *data)
2991 struct reg_cond_life_info *rcli;
2992 int *xdata = (int *) data;
2993 unsigned int regno = xdata[0];
2995 /* Don't need to search if last flushed value was farther on in
2996 the in-order traversal. */
2997 if (xdata[1] >= (int) node->key)
3000 /* Splice out portions of the expression that refer to regno. */
3001 rcli = (struct reg_cond_life_info *) node->value;
3002 rcli->condition = elim_reg_cond (rcli->condition, regno);
3003 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
3004 rcli->stores = elim_reg_cond (rcli->stores, regno);
3006 /* If the entire condition is now false, signal the node to be removed. */
3007 if (rcli->condition == const0_rtx)
3009 xdata[1] = node->key;
3012 else if (rcli->condition == const1_rtx)
3018 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
3021 flush_reg_cond_reg (struct propagate_block_info *pbi, int regno)
3027 while (splay_tree_foreach (pbi->reg_cond_dead,
3028 flush_reg_cond_reg_1, pair) == -1)
3029 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
3031 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
3034 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
3035 For ior/and, the ADD flag determines whether we want to add the new
3036 condition X to the old one unconditionally. If it is zero, we will
3037 only return a new expression if X allows us to simplify part of
3038 OLD, otherwise we return NULL to the caller.
3039 If ADD is nonzero, we will return a new condition in all cases. The
3040 toplevel caller of one of these functions should always pass 1 for
3044 ior_reg_cond (rtx old, rtx x, int add)
3048 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
3050 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
3051 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
3052 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3054 if (GET_CODE (x) == GET_CODE (old)
3055 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3059 return gen_rtx_IOR (0, old, x);
3062 switch (GET_CODE (old))
3065 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3066 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3067 if (op0 != NULL || op1 != NULL)
3069 if (op0 == const0_rtx)
3070 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3071 if (op1 == const0_rtx)
3072 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3073 if (op0 == const1_rtx || op1 == const1_rtx)
3076 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3077 else if (rtx_equal_p (x, op0))
3078 /* (x | A) | x ~ (x | A). */
3081 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3082 else if (rtx_equal_p (x, op1))
3083 /* (A | x) | x ~ (A | x). */
3085 return gen_rtx_IOR (0, op0, op1);
3089 return gen_rtx_IOR (0, old, x);
3092 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3093 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3094 if (op0 != NULL || op1 != NULL)
3096 if (op0 == const1_rtx)
3097 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3098 if (op1 == const1_rtx)
3099 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3100 if (op0 == const0_rtx || op1 == const0_rtx)
3103 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3104 else if (rtx_equal_p (x, op0))
3105 /* (x & A) | x ~ x. */
3108 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3109 else if (rtx_equal_p (x, op1))
3110 /* (A & x) | x ~ x. */
3112 return gen_rtx_AND (0, op0, op1);
3116 return gen_rtx_IOR (0, old, x);
3119 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3121 return not_reg_cond (op0);
3124 return gen_rtx_IOR (0, old, x);
3132 not_reg_cond (rtx x)
3134 enum rtx_code x_code;
3136 if (x == const0_rtx)
3138 else if (x == const1_rtx)
3140 x_code = GET_CODE (x);
3143 if (GET_RTX_CLASS (x_code) == '<'
3144 && GET_CODE (XEXP (x, 0)) == REG)
3146 if (XEXP (x, 1) != const0_rtx)
3149 return gen_rtx_fmt_ee (reverse_condition (x_code),
3150 VOIDmode, XEXP (x, 0), const0_rtx);
3152 return gen_rtx_NOT (0, x);
3156 and_reg_cond (rtx old, rtx x, int add)
3160 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
3162 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
3163 && GET_CODE (x) == reverse_condition (GET_CODE (old))
3164 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3166 if (GET_CODE (x) == GET_CODE (old)
3167 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3171 return gen_rtx_AND (0, old, x);
3174 switch (GET_CODE (old))
3177 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3178 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3179 if (op0 != NULL || op1 != NULL)
3181 if (op0 == const0_rtx)
3182 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3183 if (op1 == const0_rtx)
3184 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3185 if (op0 == const1_rtx || op1 == const1_rtx)
3188 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3189 else if (rtx_equal_p (x, op0))
3190 /* (x | A) & x ~ x. */
3193 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3194 else if (rtx_equal_p (x, op1))
3195 /* (A | x) & x ~ x. */
3197 return gen_rtx_IOR (0, op0, op1);
3201 return gen_rtx_AND (0, old, x);
3204 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3205 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3206 if (op0 != NULL || op1 != NULL)
3208 if (op0 == const1_rtx)
3209 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3210 if (op1 == const1_rtx)
3211 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3212 if (op0 == const0_rtx || op1 == const0_rtx)
3215 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3216 else if (rtx_equal_p (x, op0))
3217 /* (x & A) & x ~ (x & A). */
3220 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3221 else if (rtx_equal_p (x, op1))
3222 /* (A & x) & x ~ (A & x). */
3224 return gen_rtx_AND (0, op0, op1);
3228 return gen_rtx_AND (0, old, x);
3231 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3233 return not_reg_cond (op0);
3236 return gen_rtx_AND (0, old, x);
3243 /* Given a condition X, remove references to reg REGNO and return the
3244 new condition. The removal will be done so that all conditions
3245 involving REGNO are considered to evaluate to false. This function
3246 is used when the value of REGNO changes. */
3249 elim_reg_cond (rtx x, unsigned int regno)
3253 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
3255 if (REGNO (XEXP (x, 0)) == regno)
3260 switch (GET_CODE (x))
3263 op0 = elim_reg_cond (XEXP (x, 0), regno);
3264 op1 = elim_reg_cond (XEXP (x, 1), regno);
3265 if (op0 == const0_rtx || op1 == const0_rtx)
3267 if (op0 == const1_rtx)
3269 if (op1 == const1_rtx)
3271 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3273 return gen_rtx_AND (0, op0, op1);
3276 op0 = elim_reg_cond (XEXP (x, 0), regno);
3277 op1 = elim_reg_cond (XEXP (x, 1), regno);
3278 if (op0 == const1_rtx || op1 == const1_rtx)
3280 if (op0 == const0_rtx)
3282 if (op1 == const0_rtx)
3284 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3286 return gen_rtx_IOR (0, op0, op1);
3289 op0 = elim_reg_cond (XEXP (x, 0), regno);
3290 if (op0 == const0_rtx)
3292 if (op0 == const1_rtx)
3294 if (op0 != XEXP (x, 0))
3295 return not_reg_cond (op0);
3302 #endif /* HAVE_conditional_execution */
3306 /* Try to substitute the auto-inc expression INC as the address inside
3307 MEM which occurs in INSN. Currently, the address of MEM is an expression
3308 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3309 that has a single set whose source is a PLUS of INCR_REG and something
3313 attempt_auto_inc (struct propagate_block_info *pbi, rtx inc, rtx insn,
3314 rtx mem, rtx incr, rtx incr_reg)
3316 int regno = REGNO (incr_reg);
3317 rtx set = single_set (incr);
3318 rtx q = SET_DEST (set);
3319 rtx y = SET_SRC (set);
3320 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
3322 /* Make sure this reg appears only once in this insn. */
3323 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
3326 if (dead_or_set_p (incr, incr_reg)
3327 /* Mustn't autoinc an eliminable register. */
3328 && (regno >= FIRST_PSEUDO_REGISTER
3329 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
3331 /* This is the simple case. Try to make the auto-inc. If
3332 we can't, we are done. Otherwise, we will do any
3333 needed updates below. */
3334 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
3337 else if (GET_CODE (q) == REG
3338 /* PREV_INSN used here to check the semi-open interval
3340 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
3341 /* We must also check for sets of q as q may be
3342 a call clobbered hard register and there may
3343 be a call between PREV_INSN (insn) and incr. */
3344 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
3346 /* We have *p followed sometime later by q = p+size.
3347 Both p and q must be live afterward,
3348 and q is not used between INSN and its assignment.
3349 Change it to q = p, ...*q..., q = q+size.
3350 Then fall into the usual case. */
3354 emit_move_insn (q, incr_reg);
3355 insns = get_insns ();
3358 /* If we can't make the auto-inc, or can't make the
3359 replacement into Y, exit. There's no point in making
3360 the change below if we can't do the auto-inc and doing
3361 so is not correct in the pre-inc case. */
3364 validate_change (insn, &XEXP (mem, 0), inc, 1);
3365 validate_change (incr, &XEXP (y, opnum), q, 1);
3366 if (! apply_change_group ())
3369 /* We now know we'll be doing this change, so emit the
3370 new insn(s) and do the updates. */
3371 emit_insn_before (insns, insn);
3373 if (BB_HEAD (pbi->bb) == insn)
3374 BB_HEAD (pbi->bb) = insns;
3376 /* INCR will become a NOTE and INSN won't contain a
3377 use of INCR_REG. If a use of INCR_REG was just placed in
3378 the insn before INSN, make that the next use.
3379 Otherwise, invalidate it. */
3380 if (GET_CODE (PREV_INSN (insn)) == INSN
3381 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
3382 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
3383 pbi->reg_next_use[regno] = PREV_INSN (insn);
3385 pbi->reg_next_use[regno] = 0;
3390 if ((pbi->flags & PROP_REG_INFO)
3391 && !REGNO_REG_SET_P (pbi->reg_live, regno))
3392 reg_deaths[regno] = pbi->insn_num;
3394 /* REGNO is now used in INCR which is below INSN, but
3395 it previously wasn't live here. If we don't mark
3396 it as live, we'll put a REG_DEAD note for it
3397 on this insn, which is incorrect. */
3398 SET_REGNO_REG_SET (pbi->reg_live, regno);
3400 /* If there are any calls between INSN and INCR, show
3401 that REGNO now crosses them. */
3402 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
3403 if (GET_CODE (temp) == CALL_INSN)
3404 REG_N_CALLS_CROSSED (regno)++;
3406 /* Invalidate alias info for Q since we just changed its value. */
3407 clear_reg_alias_info (q);
3412 /* If we haven't returned, it means we were able to make the
3413 auto-inc, so update the status. First, record that this insn
3414 has an implicit side effect. */
3416 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
3418 /* Modify the old increment-insn to simply copy
3419 the already-incremented value of our register. */
3420 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
3423 /* If that makes it a no-op (copying the register into itself) delete
3424 it so it won't appear to be a "use" and a "set" of this
3426 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
3428 /* If the original source was dead, it's dead now. */
3431 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
3433 remove_note (incr, note);
3434 if (XEXP (note, 0) != incr_reg)
3436 unsigned int regno = REGNO (XEXP (note, 0));
3438 if ((pbi->flags & PROP_REG_INFO)
3439 && REGNO_REG_SET_P (pbi->reg_live, regno))
3441 REG_LIVE_LENGTH (regno) += pbi->insn_num - reg_deaths[regno];
3442 reg_deaths[regno] = 0;
3444 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
3448 PUT_CODE (incr, NOTE);
3449 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
3450 NOTE_SOURCE_FILE (incr) = 0;
3453 if (regno >= FIRST_PSEUDO_REGISTER)
3455 /* Count an extra reference to the reg. When a reg is
3456 incremented, spilling it is worse, so we want to make
3457 that less likely. */
3458 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3460 /* Count the increment as a setting of the register,
3461 even though it isn't a SET in rtl. */
3462 REG_N_SETS (regno)++;
3466 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3470 find_auto_inc (struct propagate_block_info *pbi, rtx x, rtx insn)
3472 rtx addr = XEXP (x, 0);
3473 HOST_WIDE_INT offset = 0;
3474 rtx set, y, incr, inc_val;
3476 int size = GET_MODE_SIZE (GET_MODE (x));
3478 if (GET_CODE (insn) == JUMP_INSN)
3481 /* Here we detect use of an index register which might be good for
3482 postincrement, postdecrement, preincrement, or predecrement. */
3484 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
3485 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
3487 if (GET_CODE (addr) != REG)
3490 regno = REGNO (addr);
3492 /* Is the next use an increment that might make auto-increment? */
3493 incr = pbi->reg_next_use[regno];
3494 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
3496 set = single_set (incr);
3497 if (set == 0 || GET_CODE (set) != SET)
3501 if (GET_CODE (y) != PLUS)
3504 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
3505 inc_val = XEXP (y, 1);
3506 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
3507 inc_val = XEXP (y, 0);
3511 if (GET_CODE (inc_val) == CONST_INT)
3513 if (HAVE_POST_INCREMENT
3514 && (INTVAL (inc_val) == size && offset == 0))
3515 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
3517 else if (HAVE_POST_DECREMENT
3518 && (INTVAL (inc_val) == -size && offset == 0))
3519 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
3521 else if (HAVE_PRE_INCREMENT
3522 && (INTVAL (inc_val) == size && offset == size))
3523 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
3525 else if (HAVE_PRE_DECREMENT
3526 && (INTVAL (inc_val) == -size && offset == -size))
3527 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
3529 else if (HAVE_POST_MODIFY_DISP && offset == 0)
3530 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3531 gen_rtx_PLUS (Pmode,
3534 insn, x, incr, addr);
3535 else if (HAVE_PRE_MODIFY_DISP && offset == INTVAL (inc_val))
3536 attempt_auto_inc (pbi, gen_rtx_PRE_MODIFY (Pmode, addr,
3537 gen_rtx_PLUS (Pmode,
3540 insn, x, incr, addr);
3542 else if (GET_CODE (inc_val) == REG
3543 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
3547 if (HAVE_POST_MODIFY_REG && offset == 0)
3548 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3549 gen_rtx_PLUS (Pmode,
3552 insn, x, incr, addr);
3556 #endif /* AUTO_INC_DEC */
3559 mark_used_reg (struct propagate_block_info *pbi, rtx reg,
3560 rtx cond ATTRIBUTE_UNUSED, rtx insn)
3562 unsigned int regno_first, regno_last, i;
3563 int some_was_live, some_was_dead, some_not_set;
3565 regno_last = regno_first = REGNO (reg);
3566 if (regno_first < FIRST_PSEUDO_REGISTER)
3567 regno_last += hard_regno_nregs[regno_first][GET_MODE (reg)] - 1;
3569 /* Find out if any of this register is live after this instruction. */
3570 some_was_live = some_was_dead = 0;
3571 for (i = regno_first; i <= regno_last; ++i)
3573 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
3574 some_was_live |= needed_regno;
3575 some_was_dead |= ! needed_regno;
3578 /* Find out if any of the register was set this insn. */
3580 for (i = regno_first; i <= regno_last; ++i)
3581 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
3583 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3585 /* Record where each reg is used, so when the reg is set we know
3586 the next insn that uses it. */
3587 pbi->reg_next_use[regno_first] = insn;
3590 if (pbi->flags & PROP_REG_INFO)
3592 if (regno_first < FIRST_PSEUDO_REGISTER)
3594 /* If this is a register we are going to try to eliminate,
3595 don't mark it live here. If we are successful in
3596 eliminating it, it need not be live unless it is used for
3597 pseudos, in which case it will have been set live when it
3598 was allocated to the pseudos. If the register will not
3599 be eliminated, reload will set it live at that point.
3601 Otherwise, record that this function uses this register. */
3602 /* ??? The PPC backend tries to "eliminate" on the pic
3603 register to itself. This should be fixed. In the mean
3604 time, hack around it. */
3606 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
3607 && (regno_first == FRAME_POINTER_REGNUM
3608 || regno_first == ARG_POINTER_REGNUM)))
3609 for (i = regno_first; i <= regno_last; ++i)
3610 regs_ever_live[i] = 1;
3614 /* Keep track of which basic block each reg appears in. */
3616 int blocknum = pbi->bb->index;
3617 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
3618 REG_BASIC_BLOCK (regno_first) = blocknum;
3619 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
3620 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
3622 /* Count (weighted) number of uses of each reg. */
3623 REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb);
3624 REG_N_REFS (regno_first)++;
3626 for (i = regno_first; i <= regno_last; ++i)
3627 if (! REGNO_REG_SET_P (pbi->reg_live, i))
3629 #ifdef ENABLE_CHECKING
3633 reg_deaths[i] = pbi->insn_num;
3637 /* Record and count the insns in which a reg dies. If it is used in
3638 this insn and was dead below the insn then it dies in this insn.
3639 If it was set in this insn, we do not make a REG_DEAD note;
3640 likewise if we already made such a note. */
3641 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
3645 /* Check for the case where the register dying partially
3646 overlaps the register set by this insn. */
3647 if (regno_first != regno_last)
3648 for (i = regno_first; i <= regno_last; ++i)
3649 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
3651 /* If none of the words in X is needed, make a REG_DEAD note.
3652 Otherwise, we must make partial REG_DEAD notes. */
3653 if (! some_was_live)
3655 if ((pbi->flags & PROP_DEATH_NOTES)
3656 && ! find_regno_note (insn, REG_DEAD, regno_first))
3658 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
3660 if (pbi->flags & PROP_REG_INFO)
3661 REG_N_DEATHS (regno_first)++;
3665 /* Don't make a REG_DEAD note for a part of a register
3666 that is set in the insn. */
3667 for (i = regno_first; i <= regno_last; ++i)
3668 if (! REGNO_REG_SET_P (pbi->reg_live, i)
3669 && ! dead_or_set_regno_p (insn, i))
3671 = alloc_EXPR_LIST (REG_DEAD,
3677 /* Mark the register as being live. */
3678 for (i = regno_first; i <= regno_last; ++i)
3680 #ifdef HAVE_conditional_execution
3681 int this_was_live = REGNO_REG_SET_P (pbi->reg_live, i);
3684 SET_REGNO_REG_SET (pbi->reg_live, i);
3686 #ifdef HAVE_conditional_execution
3687 /* If this is a conditional use, record that fact. If it is later
3688 conditionally set, we'll know to kill the register. */
3689 if (cond != NULL_RTX)
3691 splay_tree_node node;
3692 struct reg_cond_life_info *rcli;
3697 node = splay_tree_lookup (pbi->reg_cond_dead, i);
3700 /* The register was unconditionally live previously.
3701 No need to do anything. */
3705 /* The register was conditionally live previously.
3706 Subtract the new life cond from the old death cond. */
3707 rcli = (struct reg_cond_life_info *) node->value;
3708 ncond = rcli->condition;
3709 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
3711 /* If the register is now unconditionally live,
3712 remove the entry in the splay_tree. */
3713 if (ncond == const0_rtx)
3714 splay_tree_remove (pbi->reg_cond_dead, i);
3717 rcli->condition = ncond;
3718 SET_REGNO_REG_SET (pbi->reg_cond_reg,
3719 REGNO (XEXP (cond, 0)));
3725 /* The register was not previously live at all. Record
3726 the condition under which it is still dead. */
3727 rcli = xmalloc (sizeof (*rcli));
3728 rcli->condition = not_reg_cond (cond);
3729 rcli->stores = const0_rtx;
3730 rcli->orig_condition = const0_rtx;
3731 splay_tree_insert (pbi->reg_cond_dead, i,
3732 (splay_tree_value) rcli);
3734 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
3737 else if (this_was_live)
3739 /* The register may have been conditionally live previously, but
3740 is now unconditionally live. Remove it from the conditionally
3741 dead list, so that a conditional set won't cause us to think
3743 splay_tree_remove (pbi->reg_cond_dead, i);
3749 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3750 This is done assuming the registers needed from X are those that
3751 have 1-bits in PBI->REG_LIVE.
3753 INSN is the containing instruction. If INSN is dead, this function
3757 mark_used_regs (struct propagate_block_info *pbi, rtx x, rtx cond, rtx insn)
3761 int flags = pbi->flags;
3766 code = GET_CODE (x);
3787 /* If we are clobbering a MEM, mark any registers inside the address
3789 if (GET_CODE (XEXP (x, 0)) == MEM)
3790 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
3794 /* Don't bother watching stores to mems if this is not the
3795 final pass. We'll not be deleting dead stores this round. */
3796 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
3798 /* Invalidate the data for the last MEM stored, but only if MEM is
3799 something that can be stored into. */
3800 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3801 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3802 /* Needn't clear the memory set list. */
3806 rtx temp = pbi->mem_set_list;
3807 rtx prev = NULL_RTX;
3812 next = XEXP (temp, 1);
3813 if (unchanging_anti_dependence (XEXP (temp, 0), x))
3815 /* Splice temp out of the list. */
3817 XEXP (prev, 1) = next;
3819 pbi->mem_set_list = next;
3820 free_EXPR_LIST_node (temp);
3821 pbi->mem_set_list_len--;
3829 /* If the memory reference had embedded side effects (autoincrement
3830 address modes. Then we may need to kill some entries on the
3833 for_each_rtx (&PATTERN (insn), invalidate_mems_from_autoinc, pbi);
3837 if (flags & PROP_AUTOINC)
3838 find_auto_inc (pbi, x, insn);
3843 #ifdef CANNOT_CHANGE_MODE_CLASS
3844 if ((flags & PROP_REG_INFO)
3845 && GET_CODE (SUBREG_REG (x)) == REG
3846 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER)
3847 bitmap_set_bit (&subregs_of_mode, REGNO (SUBREG_REG (x))
3852 /* While we're here, optimize this case. */
3854 if (GET_CODE (x) != REG)
3859 /* See a register other than being set => mark it as needed. */
3860 mark_used_reg (pbi, x, cond, insn);
3865 rtx testreg = SET_DEST (x);
3868 /* If storing into MEM, don't show it as being used. But do
3869 show the address as being used. */
3870 if (GET_CODE (testreg) == MEM)
3873 if (flags & PROP_AUTOINC)
3874 find_auto_inc (pbi, testreg, insn);
3876 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
3877 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3881 /* Storing in STRICT_LOW_PART is like storing in a reg
3882 in that this SET might be dead, so ignore it in TESTREG.
3883 but in some other ways it is like using the reg.
3885 Storing in a SUBREG or a bit field is like storing the entire
3886 register in that if the register's value is not used
3887 then this SET is not needed. */
3888 while (GET_CODE (testreg) == STRICT_LOW_PART
3889 || GET_CODE (testreg) == ZERO_EXTRACT
3890 || GET_CODE (testreg) == SIGN_EXTRACT
3891 || GET_CODE (testreg) == SUBREG)
3893 #ifdef CANNOT_CHANGE_MODE_CLASS
3894 if ((flags & PROP_REG_INFO)
3895 && GET_CODE (testreg) == SUBREG
3896 && GET_CODE (SUBREG_REG (testreg)) == REG
3897 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER)
3898 bitmap_set_bit (&subregs_of_mode, REGNO (SUBREG_REG (testreg))
3900 + GET_MODE (testreg));
3903 /* Modifying a single register in an alternate mode
3904 does not use any of the old value. But these other
3905 ways of storing in a register do use the old value. */
3906 if (GET_CODE (testreg) == SUBREG
3907 && !((REG_BYTES (SUBREG_REG (testreg))
3908 + UNITS_PER_WORD - 1) / UNITS_PER_WORD
3909 > (REG_BYTES (testreg)
3910 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
3915 testreg = XEXP (testreg, 0);
3918 /* If this is a store into a register or group of registers,
3919 recursively scan the value being stored. */
3921 if ((GET_CODE (testreg) == PARALLEL
3922 && GET_MODE (testreg) == BLKmode)
3923 || (GET_CODE (testreg) == REG
3924 && (regno = REGNO (testreg),
3925 ! (regno == FRAME_POINTER_REGNUM
3926 && (! reload_completed || frame_pointer_needed)))
3927 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3928 && ! (regno == HARD_FRAME_POINTER_REGNUM
3929 && (! reload_completed || frame_pointer_needed))
3931 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3932 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
3937 mark_used_regs (pbi, SET_DEST (x), cond, insn);
3938 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3945 case UNSPEC_VOLATILE:
3949 /* Traditional and volatile asm instructions must be considered to use
3950 and clobber all hard registers, all pseudo-registers and all of
3951 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3953 Consider for instance a volatile asm that changes the fpu rounding
3954 mode. An insn should not be moved across this even if it only uses
3955 pseudo-regs because it might give an incorrectly rounded result.
3957 ?!? Unfortunately, marking all hard registers as live causes massive
3958 problems for the register allocator and marking all pseudos as live
3959 creates mountains of uninitialized variable warnings.
3961 So for now, just clear the memory set list and mark any regs
3962 we can find in ASM_OPERANDS as used. */
3963 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
3965 free_EXPR_LIST_list (&pbi->mem_set_list);
3966 pbi->mem_set_list_len = 0;
3969 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3970 We can not just fall through here since then we would be confused
3971 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3972 traditional asms unlike their normal usage. */
3973 if (code == ASM_OPERANDS)
3977 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
3978 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
3984 if (cond != NULL_RTX)
3987 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
3989 cond = COND_EXEC_TEST (x);
3990 x = COND_EXEC_CODE (x);
3997 /* Recursively scan the operands of this expression. */
4000 const char * const fmt = GET_RTX_FORMAT (code);
4003 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4007 /* Tail recursive case: save a function call level. */
4013 mark_used_regs (pbi, XEXP (x, i), cond, insn);
4015 else if (fmt[i] == 'E')
4018 for (j = 0; j < XVECLEN (x, i); j++)
4019 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
4028 try_pre_increment_1 (struct propagate_block_info *pbi, rtx insn)
4030 /* Find the next use of this reg. If in same basic block,
4031 make it do pre-increment or pre-decrement if appropriate. */
4032 rtx x = single_set (insn);
4033 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
4034 * INTVAL (XEXP (SET_SRC (x), 1)));
4035 int regno = REGNO (SET_DEST (x));
4036 rtx y = pbi->reg_next_use[regno];
4038 && SET_DEST (x) != stack_pointer_rtx
4039 && BLOCK_NUM (y) == BLOCK_NUM (insn)
4040 /* Don't do this if the reg dies, or gets set in y; a standard addressing
4041 mode would be better. */
4042 && ! dead_or_set_p (y, SET_DEST (x))
4043 && try_pre_increment (y, SET_DEST (x), amount))
4045 /* We have found a suitable auto-increment and already changed
4046 insn Y to do it. So flush this increment instruction. */
4047 propagate_block_delete_insn (insn);
4049 /* Count a reference to this reg for the increment insn we are
4050 deleting. When a reg is incremented, spilling it is worse,
4051 so we want to make that less likely. */
4052 if (regno >= FIRST_PSEUDO_REGISTER)
4054 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
4055 REG_N_SETS (regno)++;
4058 /* Flush any remembered memories depending on the value of
4059 the incremented register. */
4060 invalidate_mems_from_set (pbi, SET_DEST (x));
4067 /* Try to change INSN so that it does pre-increment or pre-decrement
4068 addressing on register REG in order to add AMOUNT to REG.
4069 AMOUNT is negative for pre-decrement.
4070 Returns 1 if the change could be made.
4071 This checks all about the validity of the result of modifying INSN. */
4074 try_pre_increment (rtx insn, rtx reg, HOST_WIDE_INT amount)
4078 /* Nonzero if we can try to make a pre-increment or pre-decrement.
4079 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
4081 /* Nonzero if we can try to make a post-increment or post-decrement.
4082 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
4083 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
4084 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
4087 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
4090 /* From the sign of increment, see which possibilities are conceivable
4091 on this target machine. */
4092 if (HAVE_PRE_INCREMENT && amount > 0)
4094 if (HAVE_POST_INCREMENT && amount > 0)
4097 if (HAVE_PRE_DECREMENT && amount < 0)
4099 if (HAVE_POST_DECREMENT && amount < 0)
4102 if (! (pre_ok || post_ok))
4105 /* It is not safe to add a side effect to a jump insn
4106 because if the incremented register is spilled and must be reloaded
4107 there would be no way to store the incremented value back in memory. */
4109 if (GET_CODE (insn) == JUMP_INSN)
4114 use = find_use_as_address (PATTERN (insn), reg, 0);
4115 if (post_ok && (use == 0 || use == (rtx) (size_t) 1))
4117 use = find_use_as_address (PATTERN (insn), reg, -amount);
4121 if (use == 0 || use == (rtx) (size_t) 1)
4124 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
4127 /* See if this combination of instruction and addressing mode exists. */
4128 if (! validate_change (insn, &XEXP (use, 0),
4129 gen_rtx_fmt_e (amount > 0
4130 ? (do_post ? POST_INC : PRE_INC)
4131 : (do_post ? POST_DEC : PRE_DEC),
4135 /* Record that this insn now has an implicit side effect on X. */
4136 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
4140 #endif /* AUTO_INC_DEC */
4142 /* Find the place in the rtx X where REG is used as a memory address.
4143 Return the MEM rtx that so uses it.
4144 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4145 (plus REG (const_int PLUSCONST)).
4147 If such an address does not appear, return 0.
4148 If REG appears more than once, or is used other than in such an address,
4152 find_use_as_address (rtx x, rtx reg, HOST_WIDE_INT plusconst)
4154 enum rtx_code code = GET_CODE (x);
4155 const char * const fmt = GET_RTX_FORMAT (code);
4160 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
4163 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
4164 && XEXP (XEXP (x, 0), 0) == reg
4165 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
4166 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
4169 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
4171 /* If REG occurs inside a MEM used in a bit-field reference,
4172 that is unacceptable. */
4173 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
4174 return (rtx) (size_t) 1;
4178 return (rtx) (size_t) 1;
4180 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4184 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
4188 return (rtx) (size_t) 1;
4190 else if (fmt[i] == 'E')
4193 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4195 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
4199 return (rtx) (size_t) 1;
4207 /* Write information about registers and basic blocks into FILE.
4208 This is part of making a debugging dump. */
4211 dump_regset (regset r, FILE *outf)
4216 fputs (" (nil)", outf);
4220 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
4222 fprintf (outf, " %d", i);
4223 if (i < FIRST_PSEUDO_REGISTER)
4224 fprintf (outf, " [%s]",
4229 /* Print a human-readable representation of R on the standard error
4230 stream. This function is designed to be used from within the
4234 debug_regset (regset r)
4236 dump_regset (r, stderr);
4237 putc ('\n', stderr);
4240 /* Recompute register set/reference counts immediately prior to register
4243 This avoids problems with set/reference counts changing to/from values
4244 which have special meanings to the register allocators.
4246 Additionally, the reference counts are the primary component used by the
4247 register allocators to prioritize pseudos for allocation to hard regs.
4248 More accurate reference counts generally lead to better register allocation.
4250 F is the first insn to be scanned.
4252 LOOP_STEP denotes how much loop_depth should be incremented per
4253 loop nesting level in order to increase the ref count more for
4254 references in a loop.
4256 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4257 possibly other information which is used by the register allocators. */
4260 recompute_reg_usage (rtx f ATTRIBUTE_UNUSED, int loop_step ATTRIBUTE_UNUSED)
4262 allocate_reg_life_data ();
4263 /* distribute_notes in combiner fails to convert some of the REG_UNUSED notes
4264 to REG_DEAD notes. This causes CHECK_DEAD_NOTES in sched1 to abort. To
4265 solve this update the DEATH_NOTES here. */
4266 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO | PROP_DEATH_NOTES);
4269 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4270 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4271 of the number of registers that died. */
4274 count_or_remove_death_notes (sbitmap blocks, int kill)
4281 /* This used to be a loop over all the blocks with a membership test
4282 inside the loop. That can be amazingly expensive on a large CFG
4283 when only a small number of bits are set in BLOCKs (for example,
4284 the calls from the scheduler typically have very few bits set).
4286 For extra credit, someone should convert BLOCKS to a bitmap rather
4290 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4292 count += count_or_remove_death_notes_bb (BASIC_BLOCK (i), kill);
4299 count += count_or_remove_death_notes_bb (bb, kill);
4306 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from basic
4307 block BB. Returns a count of the number of registers that died. */
4310 count_or_remove_death_notes_bb (basic_block bb, int kill)
4315 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
4319 rtx *pprev = ®_NOTES (insn);
4324 switch (REG_NOTE_KIND (link))
4327 if (GET_CODE (XEXP (link, 0)) == REG)
4329 rtx reg = XEXP (link, 0);
4332 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
4335 n = hard_regno_nregs[REGNO (reg)][GET_MODE (reg)];
4344 rtx next = XEXP (link, 1);
4345 free_EXPR_LIST_node (link);
4346 *pprev = link = next;
4352 pprev = &XEXP (link, 1);
4359 if (insn == BB_END (bb))
4366 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4367 if blocks is NULL. */
4370 clear_log_links (sbitmap blocks)
4377 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4379 free_INSN_LIST_list (&LOG_LINKS (insn));
4382 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4384 basic_block bb = BASIC_BLOCK (i);
4386 for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
4387 insn = NEXT_INSN (insn))
4389 free_INSN_LIST_list (&LOG_LINKS (insn));
4393 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4394 correspond to the hard registers, if any, set in that map. This
4395 could be done far more efficiently by having all sorts of special-cases
4396 with moving single words, but probably isn't worth the trouble. */
4399 reg_set_to_hard_reg_set (HARD_REG_SET *to, bitmap from)
4403 EXECUTE_IF_SET_IN_BITMAP
4406 if (i >= FIRST_PSEUDO_REGISTER)
4408 SET_HARD_REG_BIT (*to, i);