1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 /* This file contains the data flow analysis pass of the compiler. It
23 computes data flow information which tells combine_instructions
24 which insns to consider combining and controls register allocation.
26 Additional data flow information that is too bulky to record is
27 generated during the analysis, and is used at that time to create
28 autoincrement and autodecrement addressing.
30 The first step is dividing the function into basic blocks.
31 find_basic_blocks does this. Then life_analysis determines
32 where each register is live and where it is dead.
34 ** find_basic_blocks **
36 find_basic_blocks divides the current function's rtl into basic
37 blocks and constructs the CFG. The blocks are recorded in the
38 basic_block_info array; the CFG exists in the edge structures
39 referenced by the blocks.
41 find_basic_blocks also finds any unreachable loops and deletes them.
45 life_analysis is called immediately after find_basic_blocks.
46 It uses the basic block information to determine where each
47 hard or pseudo register is live.
49 ** live-register info **
51 The information about where each register is live is in two parts:
52 the REG_NOTES of insns, and the vector basic_block->global_live_at_start.
54 basic_block->global_live_at_start has an element for each basic
55 block, and the element is a bit-vector with a bit for each hard or
56 pseudo register. The bit is 1 if the register is live at the
57 beginning of the basic block.
59 Two types of elements can be added to an insn's REG_NOTES.
60 A REG_DEAD note is added to an insn's REG_NOTES for any register
61 that meets both of two conditions: The value in the register is not
62 needed in subsequent insns and the insn does not replace the value in
63 the register (in the case of multi-word hard registers, the value in
64 each register must be replaced by the insn to avoid a REG_DEAD note).
66 In the vast majority of cases, an object in a REG_DEAD note will be
67 used somewhere in the insn. The (rare) exception to this is if an
68 insn uses a multi-word hard register and only some of the registers are
69 needed in subsequent insns. In that case, REG_DEAD notes will be
70 provided for those hard registers that are not subsequently needed.
71 Partial REG_DEAD notes of this type do not occur when an insn sets
72 only some of the hard registers used in such a multi-word operand;
73 omitting REG_DEAD notes for objects stored in an insn is optional and
74 the desire to do so does not justify the complexity of the partial
77 REG_UNUSED notes are added for each register that is set by the insn
78 but is unused subsequently (if every register set by the insn is unused
79 and the insn does not reference memory or have some other side-effect,
80 the insn is deleted instead). If only part of a multi-word hard
81 register is used in a subsequent insn, REG_UNUSED notes are made for
82 the parts that will not be used.
84 To determine which registers are live after any insn, one can
85 start from the beginning of the basic block and scan insns, noting
86 which registers are set by each insn and which die there.
88 ** Other actions of life_analysis **
90 life_analysis sets up the LOG_LINKS fields of insns because the
91 information needed to do so is readily available.
93 life_analysis deletes insns whose only effect is to store a value
96 life_analysis notices cases where a reference to a register as
97 a memory address can be combined with a preceding or following
98 incrementation or decrementation of the register. The separate
99 instruction to increment or decrement is deleted and the address
100 is changed to a POST_INC or similar rtx.
102 Each time an incrementing or decrementing address is created,
103 a REG_INC element is added to the insn's REG_NOTES list.
105 life_analysis fills in certain vectors containing information about
106 register usage: REG_N_REFS, REG_N_DEATHS, REG_N_SETS, REG_LIVE_LENGTH,
107 REG_N_CALLS_CROSSED and REG_BASIC_BLOCK.
109 life_analysis sets current_function_sp_is_unchanging if the function
110 doesn't modify the stack pointer. */
114 Split out from life_analysis:
115 - local property discovery (bb->local_live, bb->local_set)
116 - global property computation
118 - pre/post modify transformation
126 #include "hard-reg-set.h"
127 #include "basic-block.h"
128 #include "insn-config.h"
132 #include "function.h"
141 #include "splay-tree.h"
143 #define obstack_chunk_alloc xmalloc
144 #define obstack_chunk_free free
146 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
147 the stack pointer does not matter. The value is tested only in
148 functions that have frame pointers.
149 No definition is equivalent to always zero. */
150 #ifndef EXIT_IGNORE_STACK
151 #define EXIT_IGNORE_STACK 0
154 #ifndef HAVE_epilogue
155 #define HAVE_epilogue 0
157 #ifndef HAVE_prologue
158 #define HAVE_prologue 0
160 #ifndef HAVE_sibcall_epilogue
161 #define HAVE_sibcall_epilogue 0
165 #define LOCAL_REGNO(REGNO) 0
167 #ifndef EPILOGUE_USES
168 #define EPILOGUE_USES(REGNO) 0
171 #ifdef HAVE_conditional_execution
172 #ifndef REVERSE_CONDEXEC_PREDICATES_P
173 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y))
177 /* Nonzero if the second flow pass has completed. */
180 /* Maximum register number used in this function, plus one. */
184 /* Indexed by n, giving various register information */
186 varray_type reg_n_info;
188 /* Size of a regset for the current function,
189 in (1) bytes and (2) elements. */
194 /* Regset of regs live when calls to `setjmp'-like functions happen. */
195 /* ??? Does this exist only for the setjmp-clobbered warning message? */
197 regset regs_live_at_setjmp;
199 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
200 that have to go in the same hard reg.
201 The first two regs in the list are a pair, and the next two
202 are another pair, etc. */
205 /* Callback that determines if it's ok for a function to have no
206 noreturn attribute. */
207 int (*lang_missing_noreturn_ok_p) PARAMS ((tree));
209 /* Set of registers that may be eliminable. These are handled specially
210 in updating regs_ever_live. */
212 static HARD_REG_SET elim_reg_set;
214 /* Holds information for tracking conditional register life information. */
215 struct reg_cond_life_info
217 /* A boolean expression of conditions under which a register is dead. */
219 /* Conditions under which a register is dead at the basic block end. */
222 /* A boolean expression of conditions under which a register has been
226 /* ??? Could store mask of bytes that are dead, so that we could finally
227 track lifetimes of multi-word registers accessed via subregs. */
230 /* For use in communicating between propagate_block and its subroutines.
231 Holds all information needed to compute life and def-use information. */
233 struct propagate_block_info
235 /* The basic block we're considering. */
238 /* Bit N is set if register N is conditionally or unconditionally live. */
241 /* Bit N is set if register N is set this insn. */
244 /* Element N is the next insn that uses (hard or pseudo) register N
245 within the current basic block; or zero, if there is no such insn. */
248 /* Contains a list of all the MEMs we are tracking for dead store
252 /* If non-null, record the set of registers set unconditionally in the
256 /* If non-null, record the set of registers set conditionally in the
258 regset cond_local_set;
260 #ifdef HAVE_conditional_execution
261 /* Indexed by register number, holds a reg_cond_life_info for each
262 register that is not unconditionally live or dead. */
263 splay_tree reg_cond_dead;
265 /* Bit N is set if register N is in an expression in reg_cond_dead. */
269 /* The length of mem_set_list. */
270 int mem_set_list_len;
272 /* Non-zero if the value of CC0 is live. */
275 /* Flags controling the set of information propagate_block collects. */
279 /* Maximum length of pbi->mem_set_list before we start dropping
280 new elements on the floor. */
281 #define MAX_MEM_SET_LIST_LEN 100
283 /* Have print_rtl_and_abort give the same information that fancy_abort
285 #define print_rtl_and_abort() \
286 print_rtl_and_abort_fcn (__FILE__, __LINE__, __FUNCTION__)
288 /* Forward declarations */
289 static int verify_wide_reg_1 PARAMS ((rtx *, void *));
290 static void verify_wide_reg PARAMS ((int, rtx, rtx));
291 static void verify_local_live_at_start PARAMS ((regset, basic_block));
292 static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *));
293 static void notice_stack_pointer_modification PARAMS ((rtx));
294 static void mark_reg PARAMS ((rtx, void *));
295 static void mark_regs_live_at_end PARAMS ((regset));
296 static int set_phi_alternative_reg PARAMS ((rtx, int, int, void *));
297 static void calculate_global_regs_live PARAMS ((sbitmap, sbitmap, int));
298 static void propagate_block_delete_insn PARAMS ((basic_block, rtx));
299 static rtx propagate_block_delete_libcall PARAMS ((rtx, rtx));
300 static int insn_dead_p PARAMS ((struct propagate_block_info *,
302 static int libcall_dead_p PARAMS ((struct propagate_block_info *,
304 static void mark_set_regs PARAMS ((struct propagate_block_info *,
306 static void mark_set_1 PARAMS ((struct propagate_block_info *,
307 enum rtx_code, rtx, rtx,
309 #ifdef HAVE_conditional_execution
310 static int mark_regno_cond_dead PARAMS ((struct propagate_block_info *,
312 static void free_reg_cond_life_info PARAMS ((splay_tree_value));
313 static int flush_reg_cond_reg_1 PARAMS ((splay_tree_node, void *));
314 static void flush_reg_cond_reg PARAMS ((struct propagate_block_info *,
316 static rtx elim_reg_cond PARAMS ((rtx, unsigned int));
317 static rtx ior_reg_cond PARAMS ((rtx, rtx, int));
318 static rtx not_reg_cond PARAMS ((rtx));
319 static rtx and_reg_cond PARAMS ((rtx, rtx, int));
322 static void attempt_auto_inc PARAMS ((struct propagate_block_info *,
323 rtx, rtx, rtx, rtx, rtx));
324 static void find_auto_inc PARAMS ((struct propagate_block_info *,
326 static int try_pre_increment_1 PARAMS ((struct propagate_block_info *,
328 static int try_pre_increment PARAMS ((rtx, rtx, HOST_WIDE_INT));
330 static void mark_used_reg PARAMS ((struct propagate_block_info *,
332 static void mark_used_regs PARAMS ((struct propagate_block_info *,
334 void dump_flow_info PARAMS ((FILE *));
335 void debug_flow_info PARAMS ((void));
336 static void print_rtl_and_abort_fcn PARAMS ((const char *, int,
340 static void add_to_mem_set_list PARAMS ((struct propagate_block_info *,
342 static void invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *,
344 static void invalidate_mems_from_set PARAMS ((struct propagate_block_info *,
346 static void delete_dead_jumptables PARAMS ((void));
347 static void clear_log_links PARAMS ((sbitmap));
351 check_function_return_warnings ()
353 if (warn_missing_noreturn
354 && !TREE_THIS_VOLATILE (cfun->decl)
355 && EXIT_BLOCK_PTR->pred == NULL
356 && (lang_missing_noreturn_ok_p
357 && !lang_missing_noreturn_ok_p (cfun->decl)))
358 warning ("function might be possible candidate for attribute `noreturn'");
360 /* If we have a path to EXIT, then we do return. */
361 if (TREE_THIS_VOLATILE (cfun->decl)
362 && EXIT_BLOCK_PTR->pred != NULL)
363 warning ("`noreturn' function does return");
365 /* If the clobber_return_insn appears in some basic block, then we
366 do reach the end without returning a value. */
367 else if (warn_return_type
368 && cfun->x_clobber_return_insn != NULL
369 && EXIT_BLOCK_PTR->pred != NULL)
371 int max_uid = get_max_uid ();
373 /* If clobber_return_insn was excised by jump1, then renumber_insns
374 can make max_uid smaller than the number still recorded in our rtx.
375 That's fine, since this is a quick way of verifying that the insn
376 is no longer in the chain. */
377 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
379 /* Recompute insn->block mapping, since the initial mapping is
380 set before we delete unreachable blocks. */
381 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL)
382 warning ("control reaches end of non-void function");
387 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
388 note associated with the BLOCK. */
391 first_insn_after_basic_block_note (block)
396 /* Get the first instruction in the block. */
399 if (insn == NULL_RTX)
401 if (GET_CODE (insn) == CODE_LABEL)
402 insn = NEXT_INSN (insn);
403 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
406 return NEXT_INSN (insn);
409 /* Perform data flow analysis.
410 F is the first insn of the function; FLAGS is a set of PROP_* flags
411 to be used in accumulating flow info. */
414 life_analysis (f, file, flags)
419 #ifdef ELIMINABLE_REGS
421 static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS;
424 /* Record which registers will be eliminated. We use this in
427 CLEAR_HARD_REG_SET (elim_reg_set);
429 #ifdef ELIMINABLE_REGS
430 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
431 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
433 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
437 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES);
439 /* The post-reload life analysis have (on a global basis) the same
440 registers live as was computed by reload itself. elimination
441 Otherwise offsets and such may be incorrect.
443 Reload will make some registers as live even though they do not
446 We don't want to create new auto-incs after reload, since they
447 are unlikely to be useful and can cause problems with shared
449 if (reload_completed)
450 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
452 /* We want alias analysis information for local dead store elimination. */
453 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
454 init_alias_analysis ();
456 /* Always remove no-op moves. Do this before other processing so
457 that we don't have to keep re-scanning them. */
458 delete_noop_moves (f);
460 /* Some targets can emit simpler epilogues if they know that sp was
461 not ever modified during the function. After reload, of course,
462 we've already emitted the epilogue so there's no sense searching. */
463 if (! reload_completed)
464 notice_stack_pointer_modification (f);
466 /* Allocate and zero out data structures that will record the
467 data from lifetime analysis. */
468 allocate_reg_life_data ();
469 allocate_bb_life_data ();
471 /* Find the set of registers live on function exit. */
472 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
474 /* "Update" life info from zero. It'd be nice to begin the
475 relaxation with just the exit and noreturn blocks, but that set
476 is not immediately handy. */
478 if (flags & PROP_REG_INFO)
479 memset (regs_ever_live, 0, sizeof (regs_ever_live));
480 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
483 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
484 end_alias_analysis ();
487 dump_flow_info (file);
489 free_basic_block_vars (1);
491 #ifdef ENABLE_CHECKING
495 /* Search for any REG_LABEL notes which reference deleted labels. */
496 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
498 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
500 if (inote && GET_CODE (inote) == NOTE_INSN_DELETED_LABEL)
505 /* Removing dead insns should've made jumptables really dead. */
506 delete_dead_jumptables ();
509 /* A subroutine of verify_wide_reg, called through for_each_rtx.
510 Search for REGNO. If found, abort if it is not wider than word_mode. */
513 verify_wide_reg_1 (px, pregno)
518 unsigned int regno = *(int *) pregno;
520 if (GET_CODE (x) == REG && REGNO (x) == regno)
522 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
529 /* A subroutine of verify_local_live_at_start. Search through insns
530 between HEAD and END looking for register REGNO. */
533 verify_wide_reg (regno, head, end)
540 && for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no))
544 head = NEXT_INSN (head);
547 /* We didn't find the register at all. Something's way screwy. */
549 fprintf (rtl_dump_file, "Aborting in verify_wide_reg; reg %d\n", regno);
550 print_rtl_and_abort ();
553 /* A subroutine of update_life_info. Verify that there are no untoward
554 changes in live_at_start during a local update. */
557 verify_local_live_at_start (new_live_at_start, bb)
558 regset new_live_at_start;
561 if (reload_completed)
563 /* After reload, there are no pseudos, nor subregs of multi-word
564 registers. The regsets should exactly match. */
565 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
569 fprintf (rtl_dump_file,
570 "live_at_start mismatch in bb %d, aborting\n",
572 debug_bitmap_file (rtl_dump_file, bb->global_live_at_start);
573 debug_bitmap_file (rtl_dump_file, new_live_at_start);
575 print_rtl_and_abort ();
582 /* Find the set of changed registers. */
583 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
585 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
587 /* No registers should die. */
588 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
591 fprintf (rtl_dump_file,
592 "Register %d died unexpectedly in block %d\n", i,
594 print_rtl_and_abort ();
597 /* Verify that the now-live register is wider than word_mode. */
598 verify_wide_reg (i, bb->head, bb->end);
603 /* Updates life information starting with the basic blocks set in BLOCKS.
604 If BLOCKS is null, consider it to be the universal set.
606 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
607 we are only expecting local modifications to basic blocks. If we find
608 extra registers live at the beginning of a block, then we either killed
609 useful data, or we have a broken split that wants data not provided.
610 If we find registers removed from live_at_start, that means we have
611 a broken peephole that is killing a register it shouldn't.
613 ??? This is not true in one situation -- when a pre-reload splitter
614 generates subregs of a multi-word pseudo, current life analysis will
615 lose the kill. So we _can_ have a pseudo go live. How irritating.
617 Including PROP_REG_INFO does not properly refresh regs_ever_live
618 unless the caller resets it to zero. */
621 update_life_info (blocks, extent, prop_flags)
623 enum update_life_extent extent;
627 regset_head tmp_head;
630 tmp = INITIALIZE_REG_SET (tmp_head);
632 timevar_push ((extent == UPDATE_LIFE_LOCAL || blocks)
633 ? TV_LIFE_UPDATE : TV_LIFE);
635 /* Changes to the CFG are only allowed when
636 doing a global update for the entire CFG. */
637 if ((prop_flags & PROP_ALLOW_CFG_CHANGES)
638 && (extent == UPDATE_LIFE_LOCAL || blocks))
641 /* Clear log links in case we are asked to (re)compute them. */
642 if (prop_flags & PROP_LOG_LINKS)
643 clear_log_links (blocks);
645 /* For a global update, we go through the relaxation process again. */
646 if (extent != UPDATE_LIFE_LOCAL)
652 calculate_global_regs_live (blocks, blocks,
653 prop_flags & (PROP_SCAN_DEAD_CODE
654 | PROP_ALLOW_CFG_CHANGES));
656 if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
657 != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
660 /* Removing dead code may allow the CFG to be simplified which
661 in turn may allow for further dead code detection / removal. */
662 for (i = n_basic_blocks - 1; i >= 0; --i)
664 basic_block bb = BASIC_BLOCK (i);
666 COPY_REG_SET (tmp, bb->global_live_at_end);
667 changed |= propagate_block (bb, tmp, NULL, NULL,
668 prop_flags & (PROP_SCAN_DEAD_CODE
669 | PROP_KILL_DEAD_CODE));
672 if (! changed || ! cleanup_cfg (CLEANUP_EXPENSIVE))
676 /* If asked, remove notes from the blocks we'll update. */
677 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
678 count_or_remove_death_notes (blocks, 1);
683 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
685 basic_block bb = BASIC_BLOCK (i);
687 COPY_REG_SET (tmp, bb->global_live_at_end);
688 propagate_block (bb, tmp, NULL, NULL, prop_flags);
690 if (extent == UPDATE_LIFE_LOCAL)
691 verify_local_live_at_start (tmp, bb);
696 for (i = n_basic_blocks - 1; i >= 0; --i)
698 basic_block bb = BASIC_BLOCK (i);
700 COPY_REG_SET (tmp, bb->global_live_at_end);
701 propagate_block (bb, tmp, NULL, NULL, prop_flags);
703 if (extent == UPDATE_LIFE_LOCAL)
704 verify_local_live_at_start (tmp, bb);
710 if (prop_flags & PROP_REG_INFO)
712 /* The only pseudos that are live at the beginning of the function
713 are those that were not set anywhere in the function. local-alloc
714 doesn't know how to handle these correctly, so mark them as not
715 local to any one basic block. */
716 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
717 FIRST_PSEUDO_REGISTER, i,
718 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
720 /* We have a problem with any pseudoreg that lives across the setjmp.
721 ANSI says that if a user variable does not change in value between
722 the setjmp and the longjmp, then the longjmp preserves it. This
723 includes longjmp from a place where the pseudo appears dead.
724 (In principle, the value still exists if it is in scope.)
725 If the pseudo goes in a hard reg, some other value may occupy
726 that hard reg where this pseudo is dead, thus clobbering the pseudo.
727 Conclusion: such a pseudo must not go in a hard reg. */
728 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
729 FIRST_PSEUDO_REGISTER, i,
731 if (regno_reg_rtx[i] != 0)
733 REG_LIVE_LENGTH (i) = -1;
734 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
738 timevar_pop ((extent == UPDATE_LIFE_LOCAL || blocks)
739 ? TV_LIFE_UPDATE : TV_LIFE);
742 /* Free the variables allocated by find_basic_blocks.
744 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
747 free_basic_block_vars (keep_head_end_p)
750 if (! keep_head_end_p)
752 if (basic_block_info)
755 VARRAY_FREE (basic_block_info);
759 ENTRY_BLOCK_PTR->aux = NULL;
760 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
761 EXIT_BLOCK_PTR->aux = NULL;
762 EXIT_BLOCK_PTR->global_live_at_start = NULL;
766 /* Delete any insns that copy a register to itself. */
769 delete_noop_moves (f)
770 rtx f ATTRIBUTE_UNUSED;
776 for (i = 0; i < n_basic_blocks; i++)
778 bb = BASIC_BLOCK (i);
779 for (insn = bb->head; insn != NEXT_INSN (bb->end); insn = next)
781 next = NEXT_INSN (insn);
782 if (INSN_P (insn) && noop_move_p (insn))
786 /* If we're about to remove the first insn of a libcall
787 then move the libcall note to the next real insn and
788 update the retval note. */
789 if ((note = find_reg_note (insn, REG_LIBCALL, NULL_RTX))
790 && XEXP (note, 0) != insn)
792 rtx new_libcall_insn = next_real_insn (insn);
793 rtx retval_note = find_reg_note (XEXP (note, 0),
794 REG_RETVAL, NULL_RTX);
795 REG_NOTES (new_libcall_insn)
796 = gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0),
797 REG_NOTES (new_libcall_insn));
798 XEXP (retval_note, 0) = new_libcall_insn;
801 /* Do not call delete_insn here since that may change
802 the basic block boundaries which upsets some callers. */
803 PUT_CODE (insn, NOTE);
804 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
805 NOTE_SOURCE_FILE (insn) = 0;
807 purge_dead_edges (bb);
813 /* Delete any jump tables never referenced. We can't delete them at the
814 time of removing tablejump insn as they are referenced by the preceeding
815 insns computing the destination, so we delay deleting and garbagecollect
816 them once life information is computed. */
818 delete_dead_jumptables ()
821 for (insn = get_insns (); insn; insn = next)
823 next = NEXT_INSN (insn);
824 if (GET_CODE (insn) == CODE_LABEL
825 && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
826 && GET_CODE (next) == JUMP_INSN
827 && (GET_CODE (PATTERN (next)) == ADDR_VEC
828 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
831 fprintf (rtl_dump_file, "Dead jumptable %i removed\n", INSN_UID (insn));
832 delete_insn (NEXT_INSN (insn));
834 next = NEXT_INSN (next);
839 /* Determine if the stack pointer is constant over the life of the function.
840 Only useful before prologues have been emitted. */
843 notice_stack_pointer_modification_1 (x, pat, data)
845 rtx pat ATTRIBUTE_UNUSED;
846 void *data ATTRIBUTE_UNUSED;
848 if (x == stack_pointer_rtx
849 /* The stack pointer is only modified indirectly as the result
850 of a push until later in flow. See the comments in rtl.texi
851 regarding Embedded Side-Effects on Addresses. */
852 || (GET_CODE (x) == MEM
853 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
854 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
855 current_function_sp_is_unchanging = 0;
859 notice_stack_pointer_modification (f)
864 /* Assume that the stack pointer is unchanging if alloca hasn't
866 current_function_sp_is_unchanging = !current_function_calls_alloca;
867 if (! current_function_sp_is_unchanging)
870 for (insn = f; insn; insn = NEXT_INSN (insn))
874 /* Check if insn modifies the stack pointer. */
875 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
877 if (! current_function_sp_is_unchanging)
883 /* Mark a register in SET. Hard registers in large modes get all
884 of their component registers set as well. */
891 regset set = (regset) xset;
892 int regno = REGNO (reg);
894 if (GET_MODE (reg) == BLKmode)
897 SET_REGNO_REG_SET (set, regno);
898 if (regno < FIRST_PSEUDO_REGISTER)
900 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
902 SET_REGNO_REG_SET (set, regno + n);
906 /* Mark those regs which are needed at the end of the function as live
907 at the end of the last basic block. */
910 mark_regs_live_at_end (set)
915 /* If exiting needs the right stack value, consider the stack pointer
916 live at the end of the function. */
917 if ((HAVE_epilogue && reload_completed)
918 || ! EXIT_IGNORE_STACK
919 || (! FRAME_POINTER_REQUIRED
920 && ! current_function_calls_alloca
921 && flag_omit_frame_pointer)
922 || current_function_sp_is_unchanging)
924 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
927 /* Mark the frame pointer if needed at the end of the function. If
928 we end up eliminating it, it will be removed from the live list
929 of each basic block by reload. */
931 if (! reload_completed || frame_pointer_needed)
933 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
934 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
935 /* If they are different, also mark the hard frame pointer as live. */
936 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
937 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
941 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
942 /* Many architectures have a GP register even without flag_pic.
943 Assume the pic register is not in use, or will be handled by
944 other means, if it is not fixed. */
945 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
946 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
947 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
950 /* Mark all global registers, and all registers used by the epilogue
951 as being live at the end of the function since they may be
952 referenced by our caller. */
953 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
954 if (global_regs[i] || EPILOGUE_USES (i))
955 SET_REGNO_REG_SET (set, i);
957 if (HAVE_epilogue && reload_completed)
959 /* Mark all call-saved registers that we actually used. */
960 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
961 if (regs_ever_live[i] && ! LOCAL_REGNO (i)
962 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
963 SET_REGNO_REG_SET (set, i);
966 #ifdef EH_RETURN_DATA_REGNO
967 /* Mark the registers that will contain data for the handler. */
968 if (reload_completed && current_function_calls_eh_return)
971 unsigned regno = EH_RETURN_DATA_REGNO(i);
972 if (regno == INVALID_REGNUM)
974 SET_REGNO_REG_SET (set, regno);
977 #ifdef EH_RETURN_STACKADJ_RTX
978 if ((! HAVE_epilogue || ! reload_completed)
979 && current_function_calls_eh_return)
981 rtx tmp = EH_RETURN_STACKADJ_RTX;
982 if (tmp && REG_P (tmp))
986 #ifdef EH_RETURN_HANDLER_RTX
987 if ((! HAVE_epilogue || ! reload_completed)
988 && current_function_calls_eh_return)
990 rtx tmp = EH_RETURN_HANDLER_RTX;
991 if (tmp && REG_P (tmp))
996 /* Mark function return value. */
997 diddle_return_value (mark_reg, set);
1000 /* Callback function for for_each_successor_phi. DATA is a regset.
1001 Sets the SRC_REGNO, the regno of the phi alternative for phi node
1002 INSN, in the regset. */
1005 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
1006 rtx insn ATTRIBUTE_UNUSED;
1007 int dest_regno ATTRIBUTE_UNUSED;
1011 regset live = (regset) data;
1012 SET_REGNO_REG_SET (live, src_regno);
1016 /* Propagate global life info around the graph of basic blocks. Begin
1017 considering blocks with their corresponding bit set in BLOCKS_IN.
1018 If BLOCKS_IN is null, consider it the universal set.
1020 BLOCKS_OUT is set for every block that was changed. */
1023 calculate_global_regs_live (blocks_in, blocks_out, flags)
1024 sbitmap blocks_in, blocks_out;
1027 basic_block *queue, *qhead, *qtail, *qend;
1028 regset tmp, new_live_at_end, call_used;
1029 regset_head tmp_head, call_used_head;
1030 regset_head new_live_at_end_head;
1033 tmp = INITIALIZE_REG_SET (tmp_head);
1034 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
1035 call_used = INITIALIZE_REG_SET (call_used_head);
1037 /* Inconveniently, this is only redily available in hard reg set form. */
1038 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
1039 if (call_used_regs[i])
1040 SET_REGNO_REG_SET (call_used, i);
1042 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1043 because the `head == tail' style test for an empty queue doesn't
1044 work with a full queue. */
1045 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
1047 qhead = qend = queue + n_basic_blocks + 2;
1049 /* Queue the blocks set in the initial mask. Do this in reverse block
1050 number order so that we are more likely for the first round to do
1051 useful work. We use AUX non-null to flag that the block is queued. */
1054 /* Clear out the garbage that might be hanging out in bb->aux. */
1055 for (i = n_basic_blocks - 1; i >= 0; --i)
1056 BASIC_BLOCK (i)->aux = NULL;
1058 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
1060 basic_block bb = BASIC_BLOCK (i);
1067 for (i = 0; i < n_basic_blocks; ++i)
1069 basic_block bb = BASIC_BLOCK (i);
1076 sbitmap_zero (blocks_out);
1078 /* We work through the queue until there are no more blocks. What
1079 is live at the end of this block is precisely the union of what
1080 is live at the beginning of all its successors. So, we set its
1081 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1082 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1083 this block by walking through the instructions in this block in
1084 reverse order and updating as we go. If that changed
1085 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1086 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1088 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1089 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1090 must either be live at the end of the block, or used within the
1091 block. In the latter case, it will certainly never disappear
1092 from GLOBAL_LIVE_AT_START. In the former case, the register
1093 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1094 for one of the successor blocks. By induction, that cannot
1096 while (qhead != qtail)
1098 int rescan, changed;
1107 /* Begin by propagating live_at_start from the successor blocks. */
1108 CLEAR_REG_SET (new_live_at_end);
1109 for (e = bb->succ; e; e = e->succ_next)
1111 basic_block sb = e->dest;
1113 /* Call-clobbered registers die across exception and call edges. */
1114 /* ??? Abnormal call edges ignored for the moment, as this gets
1115 confused by sibling call edges, which crashes reg-stack. */
1116 if (e->flags & EDGE_EH)
1118 bitmap_operation (tmp, sb->global_live_at_start,
1119 call_used, BITMAP_AND_COMPL);
1120 IOR_REG_SET (new_live_at_end, tmp);
1123 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
1126 /* The all-important stack pointer must always be live. */
1127 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
1129 /* Before reload, there are a few registers that must be forced
1130 live everywhere -- which might not already be the case for
1131 blocks within infinite loops. */
1132 if (! reload_completed)
1134 /* Any reference to any pseudo before reload is a potential
1135 reference of the frame pointer. */
1136 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
1138 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1139 /* Pseudos with argument area equivalences may require
1140 reloading via the argument pointer. */
1141 if (fixed_regs[ARG_POINTER_REGNUM])
1142 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
1145 /* Any constant, or pseudo with constant equivalences, may
1146 require reloading from memory using the pic register. */
1147 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
1148 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
1149 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
1152 /* Regs used in phi nodes are not included in
1153 global_live_at_start, since they are live only along a
1154 particular edge. Set those regs that are live because of a
1155 phi node alternative corresponding to this particular block. */
1157 for_each_successor_phi (bb, &set_phi_alternative_reg,
1160 if (bb == ENTRY_BLOCK_PTR)
1162 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1166 /* On our first pass through this block, we'll go ahead and continue.
1167 Recognize first pass by local_set NULL. On subsequent passes, we
1168 get to skip out early if live_at_end wouldn't have changed. */
1170 if (bb->local_set == NULL)
1172 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1173 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1178 /* If any bits were removed from live_at_end, we'll have to
1179 rescan the block. This wouldn't be necessary if we had
1180 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1181 local_live is really dependent on live_at_end. */
1182 CLEAR_REG_SET (tmp);
1183 rescan = bitmap_operation (tmp, bb->global_live_at_end,
1184 new_live_at_end, BITMAP_AND_COMPL);
1188 /* If any of the registers in the new live_at_end set are
1189 conditionally set in this basic block, we must rescan.
1190 This is because conditional lifetimes at the end of the
1191 block do not just take the live_at_end set into account,
1192 but also the liveness at the start of each successor
1193 block. We can miss changes in those sets if we only
1194 compare the new live_at_end against the previous one. */
1195 CLEAR_REG_SET (tmp);
1196 rescan = bitmap_operation (tmp, new_live_at_end,
1197 bb->cond_local_set, BITMAP_AND);
1202 /* Find the set of changed bits. Take this opportunity
1203 to notice that this set is empty and early out. */
1204 CLEAR_REG_SET (tmp);
1205 changed = bitmap_operation (tmp, bb->global_live_at_end,
1206 new_live_at_end, BITMAP_XOR);
1210 /* If any of the changed bits overlap with local_set,
1211 we'll have to rescan the block. Detect overlap by
1212 the AND with ~local_set turning off bits. */
1213 rescan = bitmap_operation (tmp, tmp, bb->local_set,
1218 /* Let our caller know that BB changed enough to require its
1219 death notes updated. */
1221 SET_BIT (blocks_out, bb->index);
1225 /* Add to live_at_start the set of all registers in
1226 new_live_at_end that aren't in the old live_at_end. */
1228 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
1230 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1232 changed = bitmap_operation (bb->global_live_at_start,
1233 bb->global_live_at_start,
1240 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1242 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1243 into live_at_start. */
1244 propagate_block (bb, new_live_at_end, bb->local_set,
1245 bb->cond_local_set, flags);
1247 /* If live_at start didn't change, no need to go farther. */
1248 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
1251 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
1254 /* Queue all predecessors of BB so that we may re-examine
1255 their live_at_end. */
1256 for (e = bb->pred; e; e = e->pred_next)
1258 basic_block pb = e->src;
1259 if (pb->aux == NULL)
1270 FREE_REG_SET (new_live_at_end);
1271 FREE_REG_SET (call_used);
1275 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
1277 basic_block bb = BASIC_BLOCK (i);
1278 FREE_REG_SET (bb->local_set);
1279 FREE_REG_SET (bb->cond_local_set);
1284 for (i = n_basic_blocks - 1; i >= 0; --i)
1286 basic_block bb = BASIC_BLOCK (i);
1287 FREE_REG_SET (bb->local_set);
1288 FREE_REG_SET (bb->cond_local_set);
1295 /* Subroutines of life analysis. */
1297 /* Allocate the permanent data structures that represent the results
1298 of life analysis. Not static since used also for stupid life analysis. */
1301 allocate_bb_life_data ()
1305 for (i = 0; i < n_basic_blocks; i++)
1307 basic_block bb = BASIC_BLOCK (i);
1309 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1310 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1313 ENTRY_BLOCK_PTR->global_live_at_end
1314 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1315 EXIT_BLOCK_PTR->global_live_at_start
1316 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1318 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1322 allocate_reg_life_data ()
1326 max_regno = max_reg_num ();
1328 /* Recalculate the register space, in case it has grown. Old style
1329 vector oriented regsets would set regset_{size,bytes} here also. */
1330 allocate_reg_info (max_regno, FALSE, FALSE);
1332 /* Reset all the data we'll collect in propagate_block and its
1334 for (i = 0; i < max_regno; i++)
1338 REG_N_DEATHS (i) = 0;
1339 REG_N_CALLS_CROSSED (i) = 0;
1340 REG_LIVE_LENGTH (i) = 0;
1341 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
1345 /* Delete dead instructions for propagate_block. */
1348 propagate_block_delete_insn (bb, insn)
1352 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
1355 /* If the insn referred to a label, and that label was attached to
1356 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1357 pretty much mandatory to delete it, because the ADDR_VEC may be
1358 referencing labels that no longer exist.
1360 INSN may reference a deleted label, particularly when a jump
1361 table has been optimized into a direct jump. There's no
1362 real good way to fix up the reference to the deleted label
1363 when the label is deleted, so we just allow it here.
1365 After dead code elimination is complete, we do search for
1366 any REG_LABEL notes which reference deleted labels as a
1369 if (inote && GET_CODE (inote) == CODE_LABEL)
1371 rtx label = XEXP (inote, 0);
1374 /* The label may be forced if it has been put in the constant
1375 pool. If that is the only use we must discard the table
1376 jump following it, but not the label itself. */
1377 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
1378 && (next = next_nonnote_insn (label)) != NULL
1379 && GET_CODE (next) == JUMP_INSN
1380 && (GET_CODE (PATTERN (next)) == ADDR_VEC
1381 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
1383 rtx pat = PATTERN (next);
1384 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
1385 int len = XVECLEN (pat, diff_vec_p);
1388 for (i = 0; i < len; i++)
1389 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
1395 if (bb->end == insn)
1399 purge_dead_edges (bb);
1402 /* Delete dead libcalls for propagate_block. Return the insn
1403 before the libcall. */
1406 propagate_block_delete_libcall ( insn, note)
1409 rtx first = XEXP (note, 0);
1410 rtx before = PREV_INSN (first);
1412 delete_insn_chain (first, insn);
1416 /* Update the life-status of regs for one insn. Return the previous insn. */
1419 propagate_one_insn (pbi, insn)
1420 struct propagate_block_info *pbi;
1423 rtx prev = PREV_INSN (insn);
1424 int flags = pbi->flags;
1425 int insn_is_dead = 0;
1426 int libcall_is_dead = 0;
1430 if (! INSN_P (insn))
1433 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1434 if (flags & PROP_SCAN_DEAD_CODE)
1436 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
1437 libcall_is_dead = (insn_is_dead && note != 0
1438 && libcall_dead_p (pbi, note, insn));
1441 /* If an instruction consists of just dead store(s) on final pass,
1443 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
1445 /* If we're trying to delete a prologue or epilogue instruction
1446 that isn't flagged as possibly being dead, something is wrong.
1447 But if we are keeping the stack pointer depressed, we might well
1448 be deleting insns that are used to compute the amount to update
1449 it by, so they are fine. */
1450 if (reload_completed
1451 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1452 && (TYPE_RETURNS_STACK_DEPRESSED
1453 (TREE_TYPE (current_function_decl))))
1454 && (((HAVE_epilogue || HAVE_prologue)
1455 && prologue_epilogue_contains (insn))
1456 || (HAVE_sibcall_epilogue
1457 && sibcall_epilogue_contains (insn)))
1458 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
1461 /* Record sets. Do this even for dead instructions, since they
1462 would have killed the values if they hadn't been deleted. */
1463 mark_set_regs (pbi, PATTERN (insn), insn);
1465 /* CC0 is now known to be dead. Either this insn used it,
1466 in which case it doesn't anymore, or clobbered it,
1467 so the next insn can't use it. */
1470 if (libcall_is_dead)
1471 prev = propagate_block_delete_libcall ( insn, note);
1473 propagate_block_delete_insn (pbi->bb, insn);
1478 /* See if this is an increment or decrement that can be merged into
1479 a following memory address. */
1482 rtx x = single_set (insn);
1484 /* Does this instruction increment or decrement a register? */
1485 if ((flags & PROP_AUTOINC)
1487 && GET_CODE (SET_DEST (x)) == REG
1488 && (GET_CODE (SET_SRC (x)) == PLUS
1489 || GET_CODE (SET_SRC (x)) == MINUS)
1490 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1491 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1492 /* Ok, look for a following memory ref we can combine with.
1493 If one is found, change the memory ref to a PRE_INC
1494 or PRE_DEC, cancel this insn, and return 1.
1495 Return 0 if nothing has been done. */
1496 && try_pre_increment_1 (pbi, insn))
1499 #endif /* AUTO_INC_DEC */
1501 CLEAR_REG_SET (pbi->new_set);
1503 /* If this is not the final pass, and this insn is copying the value of
1504 a library call and it's dead, don't scan the insns that perform the
1505 library call, so that the call's arguments are not marked live. */
1506 if (libcall_is_dead)
1508 /* Record the death of the dest reg. */
1509 mark_set_regs (pbi, PATTERN (insn), insn);
1511 insn = XEXP (note, 0);
1512 return PREV_INSN (insn);
1514 else if (GET_CODE (PATTERN (insn)) == SET
1515 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1516 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1517 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1518 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1519 /* We have an insn to pop a constant amount off the stack.
1520 (Such insns use PLUS regardless of the direction of the stack,
1521 and any insn to adjust the stack by a constant is always a pop.)
1522 These insns, if not dead stores, have no effect on life. */
1526 /* Any regs live at the time of a call instruction must not go
1527 in a register clobbered by calls. Find all regs now live and
1528 record this for them. */
1530 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
1531 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
1532 { REG_N_CALLS_CROSSED (i)++; });
1534 /* Record sets. Do this even for dead instructions, since they
1535 would have killed the values if they hadn't been deleted. */
1536 mark_set_regs (pbi, PATTERN (insn), insn);
1538 if (GET_CODE (insn) == CALL_INSN)
1544 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1545 cond = COND_EXEC_TEST (PATTERN (insn));
1547 /* Non-constant calls clobber memory. */
1548 if (! CONST_OR_PURE_CALL_P (insn))
1550 free_EXPR_LIST_list (&pbi->mem_set_list);
1551 pbi->mem_set_list_len = 0;
1554 /* There may be extra registers to be clobbered. */
1555 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1557 note = XEXP (note, 1))
1558 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
1559 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
1560 cond, insn, pbi->flags);
1562 /* Calls change all call-used and global registers. */
1563 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1564 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1566 /* We do not want REG_UNUSED notes for these registers. */
1567 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
1569 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
1573 /* If an insn doesn't use CC0, it becomes dead since we assume
1574 that every insn clobbers it. So show it dead here;
1575 mark_used_regs will set it live if it is referenced. */
1580 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
1582 /* Sometimes we may have inserted something before INSN (such as a move)
1583 when we make an auto-inc. So ensure we will scan those insns. */
1585 prev = PREV_INSN (insn);
1588 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1594 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1595 cond = COND_EXEC_TEST (PATTERN (insn));
1597 /* Calls use their arguments. */
1598 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1600 note = XEXP (note, 1))
1601 if (GET_CODE (XEXP (note, 0)) == USE)
1602 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
1605 /* The stack ptr is used (honorarily) by a CALL insn. */
1606 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
1608 /* Calls may also reference any of the global registers,
1609 so they are made live. */
1610 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1612 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
1617 /* On final pass, update counts of how many insns in which each reg
1619 if (flags & PROP_REG_INFO)
1620 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
1621 { REG_LIVE_LENGTH (i)++; });
1626 /* Initialize a propagate_block_info struct for public consumption.
1627 Note that the structure itself is opaque to this file, but that
1628 the user can use the regsets provided here. */
1630 struct propagate_block_info *
1631 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
1633 regset live, local_set, cond_local_set;
1636 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
1639 pbi->reg_live = live;
1640 pbi->mem_set_list = NULL_RTX;
1641 pbi->mem_set_list_len = 0;
1642 pbi->local_set = local_set;
1643 pbi->cond_local_set = cond_local_set;
1647 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
1648 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
1650 pbi->reg_next_use = NULL;
1652 pbi->new_set = BITMAP_XMALLOC ();
1654 #ifdef HAVE_conditional_execution
1655 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
1656 free_reg_cond_life_info);
1657 pbi->reg_cond_reg = BITMAP_XMALLOC ();
1659 /* If this block ends in a conditional branch, for each register live
1660 from one side of the branch and not the other, record the register
1661 as conditionally dead. */
1662 if (GET_CODE (bb->end) == JUMP_INSN
1663 && any_condjump_p (bb->end))
1665 regset_head diff_head;
1666 regset diff = INITIALIZE_REG_SET (diff_head);
1667 basic_block bb_true, bb_false;
1668 rtx cond_true, cond_false, set_src;
1671 /* Identify the successor blocks. */
1672 bb_true = bb->succ->dest;
1673 if (bb->succ->succ_next != NULL)
1675 bb_false = bb->succ->succ_next->dest;
1677 if (bb->succ->flags & EDGE_FALLTHRU)
1679 basic_block t = bb_false;
1683 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
1688 /* This can happen with a conditional jump to the next insn. */
1689 if (JUMP_LABEL (bb->end) != bb_true->head)
1692 /* Simplest way to do nothing. */
1696 /* Extract the condition from the branch. */
1697 set_src = SET_SRC (pc_set (bb->end));
1698 cond_true = XEXP (set_src, 0);
1699 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
1700 GET_MODE (cond_true), XEXP (cond_true, 0),
1701 XEXP (cond_true, 1));
1702 if (GET_CODE (XEXP (set_src, 1)) == PC)
1705 cond_false = cond_true;
1709 /* Compute which register lead different lives in the successors. */
1710 if (bitmap_operation (diff, bb_true->global_live_at_start,
1711 bb_false->global_live_at_start, BITMAP_XOR))
1713 rtx reg = XEXP (cond_true, 0);
1715 if (GET_CODE (reg) == SUBREG)
1716 reg = SUBREG_REG (reg);
1718 if (GET_CODE (reg) != REG)
1721 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
1723 /* For each such register, mark it conditionally dead. */
1724 EXECUTE_IF_SET_IN_REG_SET
1727 struct reg_cond_life_info *rcli;
1730 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
1732 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
1736 rcli->condition = cond;
1737 rcli->stores = const0_rtx;
1738 rcli->orig_condition = cond;
1740 splay_tree_insert (pbi->reg_cond_dead, i,
1741 (splay_tree_value) rcli);
1745 FREE_REG_SET (diff);
1749 /* If this block has no successors, any stores to the frame that aren't
1750 used later in the block are dead. So make a pass over the block
1751 recording any such that are made and show them dead at the end. We do
1752 a very conservative and simple job here. */
1754 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1755 && (TYPE_RETURNS_STACK_DEPRESSED
1756 (TREE_TYPE (current_function_decl))))
1757 && (flags & PROP_SCAN_DEAD_CODE)
1758 && (bb->succ == NULL
1759 || (bb->succ->succ_next == NULL
1760 && bb->succ->dest == EXIT_BLOCK_PTR
1761 && ! current_function_calls_eh_return)))
1764 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
1765 if (GET_CODE (insn) == INSN
1766 && (set = single_set (insn))
1767 && GET_CODE (SET_DEST (set)) == MEM)
1769 rtx mem = SET_DEST (set);
1770 rtx canon_mem = canon_rtx (mem);
1772 /* This optimization is performed by faking a store to the
1773 memory at the end of the block. This doesn't work for
1774 unchanging memories because multiple stores to unchanging
1775 memory is illegal and alias analysis doesn't consider it. */
1776 if (RTX_UNCHANGING_P (canon_mem))
1779 if (XEXP (canon_mem, 0) == frame_pointer_rtx
1780 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
1781 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
1782 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
1783 add_to_mem_set_list (pbi, canon_mem);
1790 /* Release a propagate_block_info struct. */
1793 free_propagate_block_info (pbi)
1794 struct propagate_block_info *pbi;
1796 free_EXPR_LIST_list (&pbi->mem_set_list);
1798 BITMAP_XFREE (pbi->new_set);
1800 #ifdef HAVE_conditional_execution
1801 splay_tree_delete (pbi->reg_cond_dead);
1802 BITMAP_XFREE (pbi->reg_cond_reg);
1805 if (pbi->reg_next_use)
1806 free (pbi->reg_next_use);
1811 /* Compute the registers live at the beginning of a basic block BB from
1812 those live at the end.
1814 When called, REG_LIVE contains those live at the end. On return, it
1815 contains those live at the beginning.
1817 LOCAL_SET, if non-null, will be set with all registers killed
1818 unconditionally by this basic block.
1819 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
1820 killed conditionally by this basic block. If there is any unconditional
1821 set of a register, then the corresponding bit will be set in LOCAL_SET
1822 and cleared in COND_LOCAL_SET.
1823 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
1824 case, the resulting set will be equal to the union of the two sets that
1825 would otherwise be computed.
1827 Return non-zero if an INSN is deleted (i.e. by dead code removal). */
1830 propagate_block (bb, live, local_set, cond_local_set, flags)
1834 regset cond_local_set;
1837 struct propagate_block_info *pbi;
1841 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
1843 if (flags & PROP_REG_INFO)
1847 /* Process the regs live at the end of the block.
1848 Mark them as not local to any one basic block. */
1849 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
1850 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
1853 /* Scan the block an insn at a time from end to beginning. */
1856 for (insn = bb->end;; insn = prev)
1858 /* If this is a call to `setjmp' et al, warn if any
1859 non-volatile datum is live. */
1860 if ((flags & PROP_REG_INFO)
1861 && GET_CODE (insn) == CALL_INSN
1862 && find_reg_note (insn, REG_SETJMP, NULL))
1863 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
1865 prev = propagate_one_insn (pbi, insn);
1866 changed |= NEXT_INSN (prev) != insn;
1868 if (insn == bb->head)
1872 free_propagate_block_info (pbi);
1877 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1878 (SET expressions whose destinations are registers dead after the insn).
1879 NEEDED is the regset that says which regs are alive after the insn.
1881 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
1883 If X is the entire body of an insn, NOTES contains the reg notes
1884 pertaining to the insn. */
1887 insn_dead_p (pbi, x, call_ok, notes)
1888 struct propagate_block_info *pbi;
1891 rtx notes ATTRIBUTE_UNUSED;
1893 enum rtx_code code = GET_CODE (x);
1896 /* If flow is invoked after reload, we must take existing AUTO_INC
1897 expresions into account. */
1898 if (reload_completed)
1900 for (; notes; notes = XEXP (notes, 1))
1902 if (REG_NOTE_KIND (notes) == REG_INC)
1904 int regno = REGNO (XEXP (notes, 0));
1906 /* Don't delete insns to set global regs. */
1907 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
1908 || REGNO_REG_SET_P (pbi->reg_live, regno))
1915 /* If setting something that's a reg or part of one,
1916 see if that register's altered value will be live. */
1920 rtx r = SET_DEST (x);
1923 if (GET_CODE (r) == CC0)
1924 return ! pbi->cc0_live;
1927 /* A SET that is a subroutine call cannot be dead. */
1928 if (GET_CODE (SET_SRC (x)) == CALL)
1934 /* Don't eliminate loads from volatile memory or volatile asms. */
1935 else if (volatile_refs_p (SET_SRC (x)))
1938 if (GET_CODE (r) == MEM)
1942 if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode)
1945 canon_r = canon_rtx (r);
1947 /* Walk the set of memory locations we are currently tracking
1948 and see if one is an identical match to this memory location.
1949 If so, this memory write is dead (remember, we're walking
1950 backwards from the end of the block to the start). Since
1951 rtx_equal_p does not check the alias set or flags, we also
1952 must have the potential for them to conflict (anti_dependence). */
1953 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
1954 if (anti_dependence (r, XEXP (temp, 0)))
1956 rtx mem = XEXP (temp, 0);
1958 if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0))
1959 && (GET_MODE_SIZE (GET_MODE (canon_r))
1960 <= GET_MODE_SIZE (GET_MODE (mem))))
1964 /* Check if memory reference matches an auto increment. Only
1965 post increment/decrement or modify are valid. */
1966 if (GET_MODE (mem) == GET_MODE (r)
1967 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
1968 || GET_CODE (XEXP (mem, 0)) == POST_INC
1969 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
1970 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
1971 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
1978 while (GET_CODE (r) == SUBREG
1979 || GET_CODE (r) == STRICT_LOW_PART
1980 || GET_CODE (r) == ZERO_EXTRACT)
1983 if (GET_CODE (r) == REG)
1985 int regno = REGNO (r);
1988 if (REGNO_REG_SET_P (pbi->reg_live, regno))
1991 /* If this is a hard register, verify that subsequent
1992 words are not needed. */
1993 if (regno < FIRST_PSEUDO_REGISTER)
1995 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
1998 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
2002 /* Don't delete insns to set global regs. */
2003 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2006 /* Make sure insns to set the stack pointer aren't deleted. */
2007 if (regno == STACK_POINTER_REGNUM)
2010 /* ??? These bits might be redundant with the force live bits
2011 in calculate_global_regs_live. We would delete from
2012 sequential sets; whether this actually affects real code
2013 for anything but the stack pointer I don't know. */
2014 /* Make sure insns to set the frame pointer aren't deleted. */
2015 if (regno == FRAME_POINTER_REGNUM
2016 && (! reload_completed || frame_pointer_needed))
2018 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2019 if (regno == HARD_FRAME_POINTER_REGNUM
2020 && (! reload_completed || frame_pointer_needed))
2024 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2025 /* Make sure insns to set arg pointer are never deleted
2026 (if the arg pointer isn't fixed, there will be a USE
2027 for it, so we can treat it normally). */
2028 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2032 /* Otherwise, the set is dead. */
2038 /* If performing several activities, insn is dead if each activity
2039 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2040 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2042 else if (code == PARALLEL)
2044 int i = XVECLEN (x, 0);
2046 for (i--; i >= 0; i--)
2047 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
2048 && GET_CODE (XVECEXP (x, 0, i)) != USE
2049 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
2055 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2056 is not necessarily true for hard registers. */
2057 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
2058 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
2059 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
2062 /* We do not check other CLOBBER or USE here. An insn consisting of just
2063 a CLOBBER or just a USE should not be deleted. */
2067 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2068 return 1 if the entire library call is dead.
2069 This is true if INSN copies a register (hard or pseudo)
2070 and if the hard return reg of the call insn is dead.
2071 (The caller should have tested the destination of the SET inside
2072 INSN already for death.)
2074 If this insn doesn't just copy a register, then we don't
2075 have an ordinary libcall. In that case, cse could not have
2076 managed to substitute the source for the dest later on,
2077 so we can assume the libcall is dead.
2079 PBI is the block info giving pseudoregs live before this insn.
2080 NOTE is the REG_RETVAL note of the insn. */
2083 libcall_dead_p (pbi, note, insn)
2084 struct propagate_block_info *pbi;
2088 rtx x = single_set (insn);
2092 rtx r = SET_SRC (x);
2094 if (GET_CODE (r) == REG)
2096 rtx call = XEXP (note, 0);
2100 /* Find the call insn. */
2101 while (call != insn && GET_CODE (call) != CALL_INSN)
2102 call = NEXT_INSN (call);
2104 /* If there is none, do nothing special,
2105 since ordinary death handling can understand these insns. */
2109 /* See if the hard reg holding the value is dead.
2110 If this is a PARALLEL, find the call within it. */
2111 call_pat = PATTERN (call);
2112 if (GET_CODE (call_pat) == PARALLEL)
2114 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
2115 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
2116 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
2119 /* This may be a library call that is returning a value
2120 via invisible pointer. Do nothing special, since
2121 ordinary death handling can understand these insns. */
2125 call_pat = XVECEXP (call_pat, 0, i);
2128 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
2134 /* Return 1 if register REGNO was used before it was set, i.e. if it is
2135 live at function entry. Don't count global register variables, variables
2136 in registers that can be used for function arg passing, or variables in
2137 fixed hard registers. */
2140 regno_uninitialized (regno)
2143 if (n_basic_blocks == 0
2144 || (regno < FIRST_PSEUDO_REGISTER
2145 && (global_regs[regno]
2146 || fixed_regs[regno]
2147 || FUNCTION_ARG_REGNO_P (regno))))
2150 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
2153 /* 1 if register REGNO was alive at a place where `setjmp' was called
2154 and was set more than once or is an argument.
2155 Such regs may be clobbered by `longjmp'. */
2158 regno_clobbered_at_setjmp (regno)
2161 if (n_basic_blocks == 0)
2164 return ((REG_N_SETS (regno) > 1
2165 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
2166 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
2169 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2170 maximal list size; look for overlaps in mode and select the largest. */
2172 add_to_mem_set_list (pbi, mem)
2173 struct propagate_block_info *pbi;
2178 /* We don't know how large a BLKmode store is, so we must not
2179 take them into consideration. */
2180 if (GET_MODE (mem) == BLKmode)
2183 for (i = pbi->mem_set_list; i ; i = XEXP (i, 1))
2185 rtx e = XEXP (i, 0);
2186 if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0)))
2188 if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e)))
2191 /* If we must store a copy of the mem, we can just modify
2192 the mode of the stored copy. */
2193 if (pbi->flags & PROP_AUTOINC)
2194 PUT_MODE (e, GET_MODE (mem));
2203 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN)
2206 /* Store a copy of mem, otherwise the address may be
2207 scrogged by find_auto_inc. */
2208 if (pbi->flags & PROP_AUTOINC)
2209 mem = shallow_copy_rtx (mem);
2211 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
2212 pbi->mem_set_list_len++;
2216 /* INSN references memory, possibly using autoincrement addressing modes.
2217 Find any entries on the mem_set_list that need to be invalidated due
2218 to an address change. */
2221 invalidate_mems_from_autoinc (pbi, insn)
2222 struct propagate_block_info *pbi;
2225 rtx note = REG_NOTES (insn);
2226 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
2227 if (REG_NOTE_KIND (note) == REG_INC)
2228 invalidate_mems_from_set (pbi, XEXP (note, 0));
2231 /* EXP is a REG. Remove any dependant entries from pbi->mem_set_list. */
2234 invalidate_mems_from_set (pbi, exp)
2235 struct propagate_block_info *pbi;
2238 rtx temp = pbi->mem_set_list;
2239 rtx prev = NULL_RTX;
2244 next = XEXP (temp, 1);
2245 if (reg_overlap_mentioned_p (exp, XEXP (temp, 0)))
2247 /* Splice this entry out of the list. */
2249 XEXP (prev, 1) = next;
2251 pbi->mem_set_list = next;
2252 free_EXPR_LIST_node (temp);
2253 pbi->mem_set_list_len--;
2261 /* Process the registers that are set within X. Their bits are set to
2262 1 in the regset DEAD, because they are dead prior to this insn.
2264 If INSN is nonzero, it is the insn being processed.
2266 FLAGS is the set of operations to perform. */
2269 mark_set_regs (pbi, x, insn)
2270 struct propagate_block_info *pbi;
2273 rtx cond = NULL_RTX;
2278 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2280 if (REG_NOTE_KIND (link) == REG_INC)
2281 mark_set_1 (pbi, SET, XEXP (link, 0),
2282 (GET_CODE (x) == COND_EXEC
2283 ? COND_EXEC_TEST (x) : NULL_RTX),
2287 switch (code = GET_CODE (x))
2291 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
2295 cond = COND_EXEC_TEST (x);
2296 x = COND_EXEC_CODE (x);
2303 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2305 rtx sub = XVECEXP (x, 0, i);
2306 switch (code = GET_CODE (sub))
2309 if (cond != NULL_RTX)
2312 cond = COND_EXEC_TEST (sub);
2313 sub = COND_EXEC_CODE (sub);
2314 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
2320 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
2335 /* Process a single set, which appears in INSN. REG (which may not
2336 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2337 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2338 If the set is conditional (because it appear in a COND_EXEC), COND
2339 will be the condition. */
2342 mark_set_1 (pbi, code, reg, cond, insn, flags)
2343 struct propagate_block_info *pbi;
2345 rtx reg, cond, insn;
2348 int regno_first = -1, regno_last = -1;
2349 unsigned long not_dead = 0;
2352 /* Modifying just one hardware register of a multi-reg value or just a
2353 byte field of a register does not mean the value from before this insn
2354 is now dead. Of course, if it was dead after it's unused now. */
2356 switch (GET_CODE (reg))
2359 /* Some targets place small structures in registers for return values of
2360 functions. We have to detect this case specially here to get correct
2361 flow information. */
2362 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
2363 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
2364 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
2370 case STRICT_LOW_PART:
2371 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2373 reg = XEXP (reg, 0);
2374 while (GET_CODE (reg) == SUBREG
2375 || GET_CODE (reg) == ZERO_EXTRACT
2376 || GET_CODE (reg) == SIGN_EXTRACT
2377 || GET_CODE (reg) == STRICT_LOW_PART);
2378 if (GET_CODE (reg) == MEM)
2380 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
2384 regno_last = regno_first = REGNO (reg);
2385 if (regno_first < FIRST_PSEUDO_REGISTER)
2386 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
2390 if (GET_CODE (SUBREG_REG (reg)) == REG)
2392 enum machine_mode outer_mode = GET_MODE (reg);
2393 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
2395 /* Identify the range of registers affected. This is moderately
2396 tricky for hard registers. See alter_subreg. */
2398 regno_last = regno_first = REGNO (SUBREG_REG (reg));
2399 if (regno_first < FIRST_PSEUDO_REGISTER)
2401 regno_first += subreg_regno_offset (regno_first, inner_mode,
2404 regno_last = (regno_first
2405 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
2407 /* Since we've just adjusted the register number ranges, make
2408 sure REG matches. Otherwise some_was_live will be clear
2409 when it shouldn't have been, and we'll create incorrect
2410 REG_UNUSED notes. */
2411 reg = gen_rtx_REG (outer_mode, regno_first);
2415 /* If the number of words in the subreg is less than the number
2416 of words in the full register, we have a well-defined partial
2417 set. Otherwise the high bits are undefined.
2419 This is only really applicable to pseudos, since we just took
2420 care of multi-word hard registers. */
2421 if (((GET_MODE_SIZE (outer_mode)
2422 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
2423 < ((GET_MODE_SIZE (inner_mode)
2424 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
2425 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
2428 reg = SUBREG_REG (reg);
2432 reg = SUBREG_REG (reg);
2439 /* If this set is a MEM, then it kills any aliased writes.
2440 If this set is a REG, then it kills any MEMs which use the reg. */
2441 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2443 if (GET_CODE (reg) == REG)
2444 invalidate_mems_from_set (pbi, reg);
2446 /* If the memory reference had embedded side effects (autoincrement
2447 address modes. Then we may need to kill some entries on the
2449 if (insn && GET_CODE (reg) == MEM)
2450 invalidate_mems_from_autoinc (pbi, insn);
2452 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
2453 /* ??? With more effort we could track conditional memory life. */
2455 /* There are no REG_INC notes for SP, so we can't assume we'll see
2456 everything that invalidates it. To be safe, don't eliminate any
2457 stores though SP; none of them should be redundant anyway. */
2458 && ! reg_mentioned_p (stack_pointer_rtx, reg))
2459 add_to_mem_set_list (pbi, canon_rtx (reg));
2462 if (GET_CODE (reg) == REG
2463 && ! (regno_first == FRAME_POINTER_REGNUM
2464 && (! reload_completed || frame_pointer_needed))
2465 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2466 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
2467 && (! reload_completed || frame_pointer_needed))
2469 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2470 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
2474 int some_was_live = 0, some_was_dead = 0;
2476 for (i = regno_first; i <= regno_last; ++i)
2478 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
2481 /* Order of the set operation matters here since both
2482 sets may be the same. */
2483 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
2484 if (cond != NULL_RTX
2485 && ! REGNO_REG_SET_P (pbi->local_set, i))
2486 SET_REGNO_REG_SET (pbi->cond_local_set, i);
2488 SET_REGNO_REG_SET (pbi->local_set, i);
2490 if (code != CLOBBER)
2491 SET_REGNO_REG_SET (pbi->new_set, i);
2493 some_was_live |= needed_regno;
2494 some_was_dead |= ! needed_regno;
2497 #ifdef HAVE_conditional_execution
2498 /* Consider conditional death in deciding that the register needs
2500 if (some_was_live && ! not_dead
2501 /* The stack pointer is never dead. Well, not strictly true,
2502 but it's very difficult to tell from here. Hopefully
2503 combine_stack_adjustments will fix up the most egregious
2505 && regno_first != STACK_POINTER_REGNUM)
2507 for (i = regno_first; i <= regno_last; ++i)
2508 if (! mark_regno_cond_dead (pbi, i, cond))
2509 not_dead |= ((unsigned long) 1) << (i - regno_first);
2513 /* Additional data to record if this is the final pass. */
2514 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
2515 | PROP_DEATH_NOTES | PROP_AUTOINC))
2518 int blocknum = pbi->bb->index;
2521 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2523 y = pbi->reg_next_use[regno_first];
2525 /* The next use is no longer next, since a store intervenes. */
2526 for (i = regno_first; i <= regno_last; ++i)
2527 pbi->reg_next_use[i] = 0;
2530 if (flags & PROP_REG_INFO)
2532 for (i = regno_first; i <= regno_last; ++i)
2534 /* Count (weighted) references, stores, etc. This counts a
2535 register twice if it is modified, but that is correct. */
2536 REG_N_SETS (i) += 1;
2537 REG_N_REFS (i) += 1;
2538 REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb);
2540 /* The insns where a reg is live are normally counted
2541 elsewhere, but we want the count to include the insn
2542 where the reg is set, and the normal counting mechanism
2543 would not count it. */
2544 REG_LIVE_LENGTH (i) += 1;
2547 /* If this is a hard reg, record this function uses the reg. */
2548 if (regno_first < FIRST_PSEUDO_REGISTER)
2550 for (i = regno_first; i <= regno_last; i++)
2551 regs_ever_live[i] = 1;
2555 /* Keep track of which basic blocks each reg appears in. */
2556 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
2557 REG_BASIC_BLOCK (regno_first) = blocknum;
2558 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
2559 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
2563 if (! some_was_dead)
2565 if (flags & PROP_LOG_LINKS)
2567 /* Make a logical link from the next following insn
2568 that uses this register, back to this insn.
2569 The following insns have already been processed.
2571 We don't build a LOG_LINK for hard registers containing
2572 in ASM_OPERANDs. If these registers get replaced,
2573 we might wind up changing the semantics of the insn,
2574 even if reload can make what appear to be valid
2575 assignments later. */
2576 if (y && (BLOCK_NUM (y) == blocknum)
2577 && (regno_first >= FIRST_PSEUDO_REGISTER
2578 || asm_noperands (PATTERN (y)) < 0))
2579 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
2584 else if (! some_was_live)
2586 if (flags & PROP_REG_INFO)
2587 REG_N_DEATHS (regno_first) += 1;
2589 if (flags & PROP_DEATH_NOTES)
2591 /* Note that dead stores have already been deleted
2592 when possible. If we get here, we have found a
2593 dead store that cannot be eliminated (because the
2594 same insn does something useful). Indicate this
2595 by marking the reg being set as dying here. */
2597 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2602 if (flags & PROP_DEATH_NOTES)
2604 /* This is a case where we have a multi-word hard register
2605 and some, but not all, of the words of the register are
2606 needed in subsequent insns. Write REG_UNUSED notes
2607 for those parts that were not needed. This case should
2610 for (i = regno_first; i <= regno_last; ++i)
2611 if (! REGNO_REG_SET_P (pbi->reg_live, i))
2613 = alloc_EXPR_LIST (REG_UNUSED,
2614 gen_rtx_REG (reg_raw_mode[i], i),
2620 /* Mark the register as being dead. */
2622 /* The stack pointer is never dead. Well, not strictly true,
2623 but it's very difficult to tell from here. Hopefully
2624 combine_stack_adjustments will fix up the most egregious
2626 && regno_first != STACK_POINTER_REGNUM)
2628 for (i = regno_first; i <= regno_last; ++i)
2629 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
2630 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
2633 else if (GET_CODE (reg) == REG)
2635 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2636 pbi->reg_next_use[regno_first] = 0;
2639 /* If this is the last pass and this is a SCRATCH, show it will be dying
2640 here and count it. */
2641 else if (GET_CODE (reg) == SCRATCH)
2643 if (flags & PROP_DEATH_NOTES)
2645 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2649 #ifdef HAVE_conditional_execution
2650 /* Mark REGNO conditionally dead.
2651 Return true if the register is now unconditionally dead. */
2654 mark_regno_cond_dead (pbi, regno, cond)
2655 struct propagate_block_info *pbi;
2659 /* If this is a store to a predicate register, the value of the
2660 predicate is changing, we don't know that the predicate as seen
2661 before is the same as that seen after. Flush all dependent
2662 conditions from reg_cond_dead. This will make all such
2663 conditionally live registers unconditionally live. */
2664 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
2665 flush_reg_cond_reg (pbi, regno);
2667 /* If this is an unconditional store, remove any conditional
2668 life that may have existed. */
2669 if (cond == NULL_RTX)
2670 splay_tree_remove (pbi->reg_cond_dead, regno);
2673 splay_tree_node node;
2674 struct reg_cond_life_info *rcli;
2677 /* Otherwise this is a conditional set. Record that fact.
2678 It may have been conditionally used, or there may be a
2679 subsequent set with a complimentary condition. */
2681 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
2684 /* The register was unconditionally live previously.
2685 Record the current condition as the condition under
2686 which it is dead. */
2687 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
2688 rcli->condition = cond;
2689 rcli->stores = cond;
2690 rcli->orig_condition = const0_rtx;
2691 splay_tree_insert (pbi->reg_cond_dead, regno,
2692 (splay_tree_value) rcli);
2694 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2696 /* Not unconditionaly dead. */
2701 /* The register was conditionally live previously.
2702 Add the new condition to the old. */
2703 rcli = (struct reg_cond_life_info *) node->value;
2704 ncond = rcli->condition;
2705 ncond = ior_reg_cond (ncond, cond, 1);
2706 if (rcli->stores == const0_rtx)
2707 rcli->stores = cond;
2708 else if (rcli->stores != const1_rtx)
2709 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
2711 /* If the register is now unconditionally dead, remove the entry
2712 in the splay_tree. A register is unconditionally dead if the
2713 dead condition ncond is true. A register is also unconditionally
2714 dead if the sum of all conditional stores is an unconditional
2715 store (stores is true), and the dead condition is identically the
2716 same as the original dead condition initialized at the end of
2717 the block. This is a pointer compare, not an rtx_equal_p
2719 if (ncond == const1_rtx
2720 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
2721 splay_tree_remove (pbi->reg_cond_dead, regno);
2724 rcli->condition = ncond;
2726 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2728 /* Not unconditionaly dead. */
2737 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2740 free_reg_cond_life_info (value)
2741 splay_tree_value value;
2743 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
2747 /* Helper function for flush_reg_cond_reg. */
2750 flush_reg_cond_reg_1 (node, data)
2751 splay_tree_node node;
2754 struct reg_cond_life_info *rcli;
2755 int *xdata = (int *) data;
2756 unsigned int regno = xdata[0];
2758 /* Don't need to search if last flushed value was farther on in
2759 the in-order traversal. */
2760 if (xdata[1] >= (int) node->key)
2763 /* Splice out portions of the expression that refer to regno. */
2764 rcli = (struct reg_cond_life_info *) node->value;
2765 rcli->condition = elim_reg_cond (rcli->condition, regno);
2766 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
2767 rcli->stores = elim_reg_cond (rcli->stores, regno);
2769 /* If the entire condition is now false, signal the node to be removed. */
2770 if (rcli->condition == const0_rtx)
2772 xdata[1] = node->key;
2775 else if (rcli->condition == const1_rtx)
2781 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2784 flush_reg_cond_reg (pbi, regno)
2785 struct propagate_block_info *pbi;
2792 while (splay_tree_foreach (pbi->reg_cond_dead,
2793 flush_reg_cond_reg_1, pair) == -1)
2794 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
2796 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
2799 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2800 For ior/and, the ADD flag determines whether we want to add the new
2801 condition X to the old one unconditionally. If it is zero, we will
2802 only return a new expression if X allows us to simplify part of
2803 OLD, otherwise we return OLD unchanged to the caller.
2804 If ADD is nonzero, we will return a new condition in all cases. The
2805 toplevel caller of one of these functions should always pass 1 for
2809 ior_reg_cond (old, x, add)
2815 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
2817 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
2818 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
2819 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2821 if (GET_CODE (x) == GET_CODE (old)
2822 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2826 return gen_rtx_IOR (0, old, x);
2829 switch (GET_CODE (old))
2832 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
2833 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
2834 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
2836 if (op0 == const0_rtx)
2838 if (op1 == const0_rtx)
2840 if (op0 == const1_rtx || op1 == const1_rtx)
2842 if (op0 == XEXP (old, 0))
2843 op0 = gen_rtx_IOR (0, op0, x);
2845 op1 = gen_rtx_IOR (0, op1, x);
2846 return gen_rtx_IOR (0, op0, op1);
2850 return gen_rtx_IOR (0, old, x);
2853 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
2854 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
2855 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
2857 if (op0 == const1_rtx)
2859 if (op1 == const1_rtx)
2861 if (op0 == const0_rtx || op1 == const0_rtx)
2863 if (op0 == XEXP (old, 0))
2864 op0 = gen_rtx_IOR (0, op0, x);
2866 op1 = gen_rtx_IOR (0, op1, x);
2867 return gen_rtx_AND (0, op0, op1);
2871 return gen_rtx_IOR (0, old, x);
2874 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
2875 if (op0 != XEXP (old, 0))
2876 return not_reg_cond (op0);
2879 return gen_rtx_IOR (0, old, x);
2890 enum rtx_code x_code;
2892 if (x == const0_rtx)
2894 else if (x == const1_rtx)
2896 x_code = GET_CODE (x);
2899 if (GET_RTX_CLASS (x_code) == '<'
2900 && GET_CODE (XEXP (x, 0)) == REG)
2902 if (XEXP (x, 1) != const0_rtx)
2905 return gen_rtx_fmt_ee (reverse_condition (x_code),
2906 VOIDmode, XEXP (x, 0), const0_rtx);
2908 return gen_rtx_NOT (0, x);
2912 and_reg_cond (old, x, add)
2918 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
2920 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
2921 && GET_CODE (x) == reverse_condition (GET_CODE (old))
2922 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2924 if (GET_CODE (x) == GET_CODE (old)
2925 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2929 return gen_rtx_AND (0, old, x);
2932 switch (GET_CODE (old))
2935 op0 = and_reg_cond (XEXP (old, 0), x, 0);
2936 op1 = and_reg_cond (XEXP (old, 1), x, 0);
2937 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
2939 if (op0 == const0_rtx)
2941 if (op1 == const0_rtx)
2943 if (op0 == const1_rtx || op1 == const1_rtx)
2945 if (op0 == XEXP (old, 0))
2946 op0 = gen_rtx_AND (0, op0, x);
2948 op1 = gen_rtx_AND (0, op1, x);
2949 return gen_rtx_IOR (0, op0, op1);
2953 return gen_rtx_AND (0, old, x);
2956 op0 = and_reg_cond (XEXP (old, 0), x, 0);
2957 op1 = and_reg_cond (XEXP (old, 1), x, 0);
2958 if (op0 != XEXP (old, 0) || op1 != XEXP (old, 1))
2960 if (op0 == const1_rtx)
2962 if (op1 == const1_rtx)
2964 if (op0 == const0_rtx || op1 == const0_rtx)
2966 if (op0 == XEXP (old, 0))
2967 op0 = gen_rtx_AND (0, op0, x);
2969 op1 = gen_rtx_AND (0, op1, x);
2970 return gen_rtx_AND (0, op0, op1);
2975 /* If X is identical to one of the existing terms of the AND,
2976 then just return what we already have. */
2977 /* ??? There really should be some sort of recursive check here in
2978 case there are nested ANDs. */
2979 if ((GET_CODE (XEXP (old, 0)) == GET_CODE (x)
2980 && REGNO (XEXP (XEXP (old, 0), 0)) == REGNO (XEXP (x, 0)))
2981 || (GET_CODE (XEXP (old, 1)) == GET_CODE (x)
2982 && REGNO (XEXP (XEXP (old, 1), 0)) == REGNO (XEXP (x, 0))))
2985 return gen_rtx_AND (0, old, x);
2988 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
2989 if (op0 != XEXP (old, 0))
2990 return not_reg_cond (op0);
2993 return gen_rtx_AND (0, old, x);
3000 /* Given a condition X, remove references to reg REGNO and return the
3001 new condition. The removal will be done so that all conditions
3002 involving REGNO are considered to evaluate to false. This function
3003 is used when the value of REGNO changes. */
3006 elim_reg_cond (x, regno)
3012 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
3014 if (REGNO (XEXP (x, 0)) == regno)
3019 switch (GET_CODE (x))
3022 op0 = elim_reg_cond (XEXP (x, 0), regno);
3023 op1 = elim_reg_cond (XEXP (x, 1), regno);
3024 if (op0 == const0_rtx || op1 == const0_rtx)
3026 if (op0 == const1_rtx)
3028 if (op1 == const1_rtx)
3030 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3032 return gen_rtx_AND (0, op0, op1);
3035 op0 = elim_reg_cond (XEXP (x, 0), regno);
3036 op1 = elim_reg_cond (XEXP (x, 1), regno);
3037 if (op0 == const1_rtx || op1 == const1_rtx)
3039 if (op0 == const0_rtx)
3041 if (op1 == const0_rtx)
3043 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3045 return gen_rtx_IOR (0, op0, op1);
3048 op0 = elim_reg_cond (XEXP (x, 0), regno);
3049 if (op0 == const0_rtx)
3051 if (op0 == const1_rtx)
3053 if (op0 != XEXP (x, 0))
3054 return not_reg_cond (op0);
3061 #endif /* HAVE_conditional_execution */
3065 /* Try to substitute the auto-inc expression INC as the address inside
3066 MEM which occurs in INSN. Currently, the address of MEM is an expression
3067 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3068 that has a single set whose source is a PLUS of INCR_REG and something
3072 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
3073 struct propagate_block_info *pbi;
3074 rtx inc, insn, mem, incr, incr_reg;
3076 int regno = REGNO (incr_reg);
3077 rtx set = single_set (incr);
3078 rtx q = SET_DEST (set);
3079 rtx y = SET_SRC (set);
3080 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
3082 /* Make sure this reg appears only once in this insn. */
3083 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
3086 if (dead_or_set_p (incr, incr_reg)
3087 /* Mustn't autoinc an eliminable register. */
3088 && (regno >= FIRST_PSEUDO_REGISTER
3089 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
3091 /* This is the simple case. Try to make the auto-inc. If
3092 we can't, we are done. Otherwise, we will do any
3093 needed updates below. */
3094 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
3097 else if (GET_CODE (q) == REG
3098 /* PREV_INSN used here to check the semi-open interval
3100 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
3101 /* We must also check for sets of q as q may be
3102 a call clobbered hard register and there may
3103 be a call between PREV_INSN (insn) and incr. */
3104 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
3106 /* We have *p followed sometime later by q = p+size.
3107 Both p and q must be live afterward,
3108 and q is not used between INSN and its assignment.
3109 Change it to q = p, ...*q..., q = q+size.
3110 Then fall into the usual case. */
3114 emit_move_insn (q, incr_reg);
3115 insns = get_insns ();
3118 /* If we can't make the auto-inc, or can't make the
3119 replacement into Y, exit. There's no point in making
3120 the change below if we can't do the auto-inc and doing
3121 so is not correct in the pre-inc case. */
3124 validate_change (insn, &XEXP (mem, 0), inc, 1);
3125 validate_change (incr, &XEXP (y, opnum), q, 1);
3126 if (! apply_change_group ())
3129 /* We now know we'll be doing this change, so emit the
3130 new insn(s) and do the updates. */
3131 emit_insns_before (insns, insn);
3133 if (pbi->bb->head == insn)
3134 pbi->bb->head = insns;
3136 /* INCR will become a NOTE and INSN won't contain a
3137 use of INCR_REG. If a use of INCR_REG was just placed in
3138 the insn before INSN, make that the next use.
3139 Otherwise, invalidate it. */
3140 if (GET_CODE (PREV_INSN (insn)) == INSN
3141 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
3142 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
3143 pbi->reg_next_use[regno] = PREV_INSN (insn);
3145 pbi->reg_next_use[regno] = 0;
3150 /* REGNO is now used in INCR which is below INSN, but
3151 it previously wasn't live here. If we don't mark
3152 it as live, we'll put a REG_DEAD note for it
3153 on this insn, which is incorrect. */
3154 SET_REGNO_REG_SET (pbi->reg_live, regno);
3156 /* If there are any calls between INSN and INCR, show
3157 that REGNO now crosses them. */
3158 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
3159 if (GET_CODE (temp) == CALL_INSN)
3160 REG_N_CALLS_CROSSED (regno)++;
3162 /* Invalidate alias info for Q since we just changed its value. */
3163 clear_reg_alias_info (q);
3168 /* If we haven't returned, it means we were able to make the
3169 auto-inc, so update the status. First, record that this insn
3170 has an implicit side effect. */
3172 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
3174 /* Modify the old increment-insn to simply copy
3175 the already-incremented value of our register. */
3176 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
3179 /* If that makes it a no-op (copying the register into itself) delete
3180 it so it won't appear to be a "use" and a "set" of this
3182 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
3184 /* If the original source was dead, it's dead now. */
3187 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
3189 remove_note (incr, note);
3190 if (XEXP (note, 0) != incr_reg)
3191 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
3194 PUT_CODE (incr, NOTE);
3195 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
3196 NOTE_SOURCE_FILE (incr) = 0;
3199 if (regno >= FIRST_PSEUDO_REGISTER)
3201 /* Count an extra reference to the reg. When a reg is
3202 incremented, spilling it is worse, so we want to make
3203 that less likely. */
3204 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3206 /* Count the increment as a setting of the register,
3207 even though it isn't a SET in rtl. */
3208 REG_N_SETS (regno)++;
3212 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3216 find_auto_inc (pbi, x, insn)
3217 struct propagate_block_info *pbi;
3221 rtx addr = XEXP (x, 0);
3222 HOST_WIDE_INT offset = 0;
3223 rtx set, y, incr, inc_val;
3225 int size = GET_MODE_SIZE (GET_MODE (x));
3227 if (GET_CODE (insn) == JUMP_INSN)
3230 /* Here we detect use of an index register which might be good for
3231 postincrement, postdecrement, preincrement, or predecrement. */
3233 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
3234 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
3236 if (GET_CODE (addr) != REG)
3239 regno = REGNO (addr);
3241 /* Is the next use an increment that might make auto-increment? */
3242 incr = pbi->reg_next_use[regno];
3243 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
3245 set = single_set (incr);
3246 if (set == 0 || GET_CODE (set) != SET)
3250 if (GET_CODE (y) != PLUS)
3253 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
3254 inc_val = XEXP (y, 1);
3255 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
3256 inc_val = XEXP (y, 0);
3260 if (GET_CODE (inc_val) == CONST_INT)
3262 if (HAVE_POST_INCREMENT
3263 && (INTVAL (inc_val) == size && offset == 0))
3264 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
3266 else if (HAVE_POST_DECREMENT
3267 && (INTVAL (inc_val) == -size && offset == 0))
3268 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
3270 else if (HAVE_PRE_INCREMENT
3271 && (INTVAL (inc_val) == size && offset == size))
3272 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
3274 else if (HAVE_PRE_DECREMENT
3275 && (INTVAL (inc_val) == -size && offset == -size))
3276 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
3278 else if (HAVE_POST_MODIFY_DISP && offset == 0)
3279 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3280 gen_rtx_PLUS (Pmode,
3283 insn, x, incr, addr);
3285 else if (GET_CODE (inc_val) == REG
3286 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
3290 if (HAVE_POST_MODIFY_REG && offset == 0)
3291 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3292 gen_rtx_PLUS (Pmode,
3295 insn, x, incr, addr);
3299 #endif /* AUTO_INC_DEC */
3302 mark_used_reg (pbi, reg, cond, insn)
3303 struct propagate_block_info *pbi;
3305 rtx cond ATTRIBUTE_UNUSED;
3308 unsigned int regno_first, regno_last, i;
3309 int some_was_live, some_was_dead, some_not_set;
3311 regno_last = regno_first = REGNO (reg);
3312 if (regno_first < FIRST_PSEUDO_REGISTER)
3313 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
3315 /* Find out if any of this register is live after this instruction. */
3316 some_was_live = some_was_dead = 0;
3317 for (i = regno_first; i <= regno_last; ++i)
3319 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
3320 some_was_live |= needed_regno;
3321 some_was_dead |= ! needed_regno;
3324 /* Find out if any of the register was set this insn. */
3326 for (i = regno_first; i <= regno_last; ++i)
3327 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
3329 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3331 /* Record where each reg is used, so when the reg is set we know
3332 the next insn that uses it. */
3333 pbi->reg_next_use[regno_first] = insn;
3336 if (pbi->flags & PROP_REG_INFO)
3338 if (regno_first < FIRST_PSEUDO_REGISTER)
3340 /* If this is a register we are going to try to eliminate,
3341 don't mark it live here. If we are successful in
3342 eliminating it, it need not be live unless it is used for
3343 pseudos, in which case it will have been set live when it
3344 was allocated to the pseudos. If the register will not
3345 be eliminated, reload will set it live at that point.
3347 Otherwise, record that this function uses this register. */
3348 /* ??? The PPC backend tries to "eliminate" on the pic
3349 register to itself. This should be fixed. In the mean
3350 time, hack around it. */
3352 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
3353 && (regno_first == FRAME_POINTER_REGNUM
3354 || regno_first == ARG_POINTER_REGNUM)))
3355 for (i = regno_first; i <= regno_last; ++i)
3356 regs_ever_live[i] = 1;
3360 /* Keep track of which basic block each reg appears in. */
3362 int blocknum = pbi->bb->index;
3363 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
3364 REG_BASIC_BLOCK (regno_first) = blocknum;
3365 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
3366 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
3368 /* Count (weighted) number of uses of each reg. */
3369 REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb);
3370 REG_N_REFS (regno_first)++;
3374 /* Record and count the insns in which a reg dies. If it is used in
3375 this insn and was dead below the insn then it dies in this insn.
3376 If it was set in this insn, we do not make a REG_DEAD note;
3377 likewise if we already made such a note. */
3378 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
3382 /* Check for the case where the register dying partially
3383 overlaps the register set by this insn. */
3384 if (regno_first != regno_last)
3385 for (i = regno_first; i <= regno_last; ++i)
3386 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
3388 /* If none of the words in X is needed, make a REG_DEAD note.
3389 Otherwise, we must make partial REG_DEAD notes. */
3390 if (! some_was_live)
3392 if ((pbi->flags & PROP_DEATH_NOTES)
3393 && ! find_regno_note (insn, REG_DEAD, regno_first))
3395 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
3397 if (pbi->flags & PROP_REG_INFO)
3398 REG_N_DEATHS (regno_first)++;
3402 /* Don't make a REG_DEAD note for a part of a register
3403 that is set in the insn. */
3404 for (i = regno_first; i <= regno_last; ++i)
3405 if (! REGNO_REG_SET_P (pbi->reg_live, i)
3406 && ! dead_or_set_regno_p (insn, i))
3408 = alloc_EXPR_LIST (REG_DEAD,
3409 gen_rtx_REG (reg_raw_mode[i], i),
3414 /* Mark the register as being live. */
3415 for (i = regno_first; i <= regno_last; ++i)
3417 SET_REGNO_REG_SET (pbi->reg_live, i);
3419 #ifdef HAVE_conditional_execution
3420 /* If this is a conditional use, record that fact. If it is later
3421 conditionally set, we'll know to kill the register. */
3422 if (cond != NULL_RTX)
3424 splay_tree_node node;
3425 struct reg_cond_life_info *rcli;
3430 node = splay_tree_lookup (pbi->reg_cond_dead, i);
3433 /* The register was unconditionally live previously.
3434 No need to do anything. */
3438 /* The register was conditionally live previously.
3439 Subtract the new life cond from the old death cond. */
3440 rcli = (struct reg_cond_life_info *) node->value;
3441 ncond = rcli->condition;
3442 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
3444 /* If the register is now unconditionally live,
3445 remove the entry in the splay_tree. */
3446 if (ncond == const0_rtx)
3447 splay_tree_remove (pbi->reg_cond_dead, i);
3450 rcli->condition = ncond;
3451 SET_REGNO_REG_SET (pbi->reg_cond_reg,
3452 REGNO (XEXP (cond, 0)));
3458 /* The register was not previously live at all. Record
3459 the condition under which it is still dead. */
3460 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
3461 rcli->condition = not_reg_cond (cond);
3462 rcli->stores = const0_rtx;
3463 rcli->orig_condition = const0_rtx;
3464 splay_tree_insert (pbi->reg_cond_dead, i,
3465 (splay_tree_value) rcli);
3467 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
3470 else if (some_was_live)
3472 /* The register may have been conditionally live previously, but
3473 is now unconditionally live. Remove it from the conditionally
3474 dead list, so that a conditional set won't cause us to think
3476 splay_tree_remove (pbi->reg_cond_dead, i);
3482 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3483 This is done assuming the registers needed from X are those that
3484 have 1-bits in PBI->REG_LIVE.
3486 INSN is the containing instruction. If INSN is dead, this function
3490 mark_used_regs (pbi, x, cond, insn)
3491 struct propagate_block_info *pbi;
3496 int flags = pbi->flags;
3499 code = GET_CODE (x);
3519 /* If we are clobbering a MEM, mark any registers inside the address
3521 if (GET_CODE (XEXP (x, 0)) == MEM)
3522 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
3526 /* Don't bother watching stores to mems if this is not the
3527 final pass. We'll not be deleting dead stores this round. */
3528 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
3530 /* Invalidate the data for the last MEM stored, but only if MEM is
3531 something that can be stored into. */
3532 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3533 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3534 /* Needn't clear the memory set list. */
3538 rtx temp = pbi->mem_set_list;
3539 rtx prev = NULL_RTX;
3544 next = XEXP (temp, 1);
3545 if (anti_dependence (XEXP (temp, 0), x))
3547 /* Splice temp out of the list. */
3549 XEXP (prev, 1) = next;
3551 pbi->mem_set_list = next;
3552 free_EXPR_LIST_node (temp);
3553 pbi->mem_set_list_len--;
3561 /* If the memory reference had embedded side effects (autoincrement
3562 address modes. Then we may need to kill some entries on the
3565 invalidate_mems_from_autoinc (pbi, insn);
3569 if (flags & PROP_AUTOINC)
3570 find_auto_inc (pbi, x, insn);
3575 #ifdef CLASS_CANNOT_CHANGE_MODE
3576 if (GET_CODE (SUBREG_REG (x)) == REG
3577 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
3578 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
3579 GET_MODE (SUBREG_REG (x))))
3580 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
3583 /* While we're here, optimize this case. */
3585 if (GET_CODE (x) != REG)
3590 /* See a register other than being set => mark it as needed. */
3591 mark_used_reg (pbi, x, cond, insn);
3596 rtx testreg = SET_DEST (x);
3599 /* If storing into MEM, don't show it as being used. But do
3600 show the address as being used. */
3601 if (GET_CODE (testreg) == MEM)
3604 if (flags & PROP_AUTOINC)
3605 find_auto_inc (pbi, testreg, insn);
3607 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
3608 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3612 /* Storing in STRICT_LOW_PART is like storing in a reg
3613 in that this SET might be dead, so ignore it in TESTREG.
3614 but in some other ways it is like using the reg.
3616 Storing in a SUBREG or a bit field is like storing the entire
3617 register in that if the register's value is not used
3618 then this SET is not needed. */
3619 while (GET_CODE (testreg) == STRICT_LOW_PART
3620 || GET_CODE (testreg) == ZERO_EXTRACT
3621 || GET_CODE (testreg) == SIGN_EXTRACT
3622 || GET_CODE (testreg) == SUBREG)
3624 #ifdef CLASS_CANNOT_CHANGE_MODE
3625 if (GET_CODE (testreg) == SUBREG
3626 && GET_CODE (SUBREG_REG (testreg)) == REG
3627 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
3628 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
3629 GET_MODE (testreg)))
3630 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
3633 /* Modifying a single register in an alternate mode
3634 does not use any of the old value. But these other
3635 ways of storing in a register do use the old value. */
3636 if (GET_CODE (testreg) == SUBREG
3637 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
3642 testreg = XEXP (testreg, 0);
3645 /* If this is a store into a register or group of registers,
3646 recursively scan the value being stored. */
3648 if ((GET_CODE (testreg) == PARALLEL
3649 && GET_MODE (testreg) == BLKmode)
3650 || (GET_CODE (testreg) == REG
3651 && (regno = REGNO (testreg),
3652 ! (regno == FRAME_POINTER_REGNUM
3653 && (! reload_completed || frame_pointer_needed)))
3654 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3655 && ! (regno == HARD_FRAME_POINTER_REGNUM
3656 && (! reload_completed || frame_pointer_needed))
3658 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3659 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
3664 mark_used_regs (pbi, SET_DEST (x), cond, insn);
3665 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3672 case UNSPEC_VOLATILE:
3676 /* Traditional and volatile asm instructions must be considered to use
3677 and clobber all hard registers, all pseudo-registers and all of
3678 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3680 Consider for instance a volatile asm that changes the fpu rounding
3681 mode. An insn should not be moved across this even if it only uses
3682 pseudo-regs because it might give an incorrectly rounded result.
3684 ?!? Unfortunately, marking all hard registers as live causes massive
3685 problems for the register allocator and marking all pseudos as live
3686 creates mountains of uninitialized variable warnings.
3688 So for now, just clear the memory set list and mark any regs
3689 we can find in ASM_OPERANDS as used. */
3690 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
3692 free_EXPR_LIST_list (&pbi->mem_set_list);
3693 pbi->mem_set_list_len = 0;
3696 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3697 We can not just fall through here since then we would be confused
3698 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3699 traditional asms unlike their normal usage. */
3700 if (code == ASM_OPERANDS)
3704 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
3705 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
3711 if (cond != NULL_RTX)
3714 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
3716 cond = COND_EXEC_TEST (x);
3717 x = COND_EXEC_CODE (x);
3721 /* We _do_not_ want to scan operands of phi nodes. Operands of
3722 a phi function are evaluated only when control reaches this
3723 block along a particular edge. Therefore, regs that appear
3724 as arguments to phi should not be added to the global live at
3732 /* Recursively scan the operands of this expression. */
3735 const char * const fmt = GET_RTX_FORMAT (code);
3738 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3742 /* Tail recursive case: save a function call level. */
3748 mark_used_regs (pbi, XEXP (x, i), cond, insn);
3750 else if (fmt[i] == 'E')
3753 for (j = 0; j < XVECLEN (x, i); j++)
3754 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
3763 try_pre_increment_1 (pbi, insn)
3764 struct propagate_block_info *pbi;
3767 /* Find the next use of this reg. If in same basic block,
3768 make it do pre-increment or pre-decrement if appropriate. */
3769 rtx x = single_set (insn);
3770 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
3771 * INTVAL (XEXP (SET_SRC (x), 1)));
3772 int regno = REGNO (SET_DEST (x));
3773 rtx y = pbi->reg_next_use[regno];
3775 && SET_DEST (x) != stack_pointer_rtx
3776 && BLOCK_NUM (y) == BLOCK_NUM (insn)
3777 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3778 mode would be better. */
3779 && ! dead_or_set_p (y, SET_DEST (x))
3780 && try_pre_increment (y, SET_DEST (x), amount))
3782 /* We have found a suitable auto-increment and already changed
3783 insn Y to do it. So flush this increment instruction. */
3784 propagate_block_delete_insn (pbi->bb, insn);
3786 /* Count a reference to this reg for the increment insn we are
3787 deleting. When a reg is incremented, spilling it is worse,
3788 so we want to make that less likely. */
3789 if (regno >= FIRST_PSEUDO_REGISTER)
3791 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3792 REG_N_SETS (regno)++;
3795 /* Flush any remembered memories depending on the value of
3796 the incremented register. */
3797 invalidate_mems_from_set (pbi, SET_DEST (x));
3804 /* Try to change INSN so that it does pre-increment or pre-decrement
3805 addressing on register REG in order to add AMOUNT to REG.
3806 AMOUNT is negative for pre-decrement.
3807 Returns 1 if the change could be made.
3808 This checks all about the validity of the result of modifying INSN. */
3811 try_pre_increment (insn, reg, amount)
3813 HOST_WIDE_INT amount;
3817 /* Nonzero if we can try to make a pre-increment or pre-decrement.
3818 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
3820 /* Nonzero if we can try to make a post-increment or post-decrement.
3821 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
3822 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
3823 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
3826 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
3829 /* From the sign of increment, see which possibilities are conceivable
3830 on this target machine. */
3831 if (HAVE_PRE_INCREMENT && amount > 0)
3833 if (HAVE_POST_INCREMENT && amount > 0)
3836 if (HAVE_PRE_DECREMENT && amount < 0)
3838 if (HAVE_POST_DECREMENT && amount < 0)
3841 if (! (pre_ok || post_ok))
3844 /* It is not safe to add a side effect to a jump insn
3845 because if the incremented register is spilled and must be reloaded
3846 there would be no way to store the incremented value back in memory. */
3848 if (GET_CODE (insn) == JUMP_INSN)
3853 use = find_use_as_address (PATTERN (insn), reg, 0);
3854 if (post_ok && (use == 0 || use == (rtx) 1))
3856 use = find_use_as_address (PATTERN (insn), reg, -amount);
3860 if (use == 0 || use == (rtx) 1)
3863 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
3866 /* See if this combination of instruction and addressing mode exists. */
3867 if (! validate_change (insn, &XEXP (use, 0),
3868 gen_rtx_fmt_e (amount > 0
3869 ? (do_post ? POST_INC : PRE_INC)
3870 : (do_post ? POST_DEC : PRE_DEC),
3874 /* Record that this insn now has an implicit side effect on X. */
3875 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
3879 #endif /* AUTO_INC_DEC */
3881 /* Find the place in the rtx X where REG is used as a memory address.
3882 Return the MEM rtx that so uses it.
3883 If PLUSCONST is nonzero, search instead for a memory address equivalent to
3884 (plus REG (const_int PLUSCONST)).
3886 If such an address does not appear, return 0.
3887 If REG appears more than once, or is used other than in such an address,
3891 find_use_as_address (x, reg, plusconst)
3894 HOST_WIDE_INT plusconst;
3896 enum rtx_code code = GET_CODE (x);
3897 const char * const fmt = GET_RTX_FORMAT (code);
3902 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
3905 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
3906 && XEXP (XEXP (x, 0), 0) == reg
3907 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
3908 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
3911 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
3913 /* If REG occurs inside a MEM used in a bit-field reference,
3914 that is unacceptable. */
3915 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
3916 return (rtx) (HOST_WIDE_INT) 1;
3920 return (rtx) (HOST_WIDE_INT) 1;
3922 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3926 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
3930 return (rtx) (HOST_WIDE_INT) 1;
3932 else if (fmt[i] == 'E')
3935 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
3937 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
3941 return (rtx) (HOST_WIDE_INT) 1;
3949 /* Write information about registers and basic blocks into FILE.
3950 This is part of making a debugging dump. */
3953 dump_regset (r, outf)
3960 fputs (" (nil)", outf);
3964 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
3966 fprintf (outf, " %d", i);
3967 if (i < FIRST_PSEUDO_REGISTER)
3968 fprintf (outf, " [%s]",
3973 /* Print a human-reaable representation of R on the standard error
3974 stream. This function is designed to be used from within the
3981 dump_regset (r, stderr);
3982 putc ('\n', stderr);
3985 /* Dump the rtl into the current debugging dump file, then abort. */
3988 print_rtl_and_abort_fcn (file, line, function)
3991 const char *function;
3995 print_rtl_with_bb (rtl_dump_file, get_insns ());
3996 fclose (rtl_dump_file);
3999 fancy_abort (file, line, function);
4002 /* Recompute register set/reference counts immediately prior to register
4005 This avoids problems with set/reference counts changing to/from values
4006 which have special meanings to the register allocators.
4008 Additionally, the reference counts are the primary component used by the
4009 register allocators to prioritize pseudos for allocation to hard regs.
4010 More accurate reference counts generally lead to better register allocation.
4012 F is the first insn to be scanned.
4014 LOOP_STEP denotes how much loop_depth should be incremented per
4015 loop nesting level in order to increase the ref count more for
4016 references in a loop.
4018 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4019 possibly other information which is used by the register allocators. */
4022 recompute_reg_usage (f, loop_step)
4023 rtx f ATTRIBUTE_UNUSED;
4024 int loop_step ATTRIBUTE_UNUSED;
4026 allocate_reg_life_data ();
4027 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
4030 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4031 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4032 of the number of registers that died. */
4035 count_or_remove_death_notes (blocks, kill)
4041 for (i = n_basic_blocks - 1; i >= 0; --i)
4046 if (blocks && ! TEST_BIT (blocks, i))
4049 bb = BASIC_BLOCK (i);
4051 for (insn = bb->head;; insn = NEXT_INSN (insn))
4055 rtx *pprev = ®_NOTES (insn);
4060 switch (REG_NOTE_KIND (link))
4063 if (GET_CODE (XEXP (link, 0)) == REG)
4065 rtx reg = XEXP (link, 0);
4068 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
4071 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
4079 rtx next = XEXP (link, 1);
4080 free_EXPR_LIST_node (link);
4081 *pprev = link = next;
4087 pprev = &XEXP (link, 1);
4094 if (insn == bb->end)
4101 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4102 if blocks is NULL. */
4105 clear_log_links (blocks)
4114 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4116 free_INSN_LIST_list (&LOG_LINKS (insn));
4119 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4121 basic_block bb = BASIC_BLOCK (i);
4123 for (insn = bb->head; insn != NEXT_INSN (bb->end);
4124 insn = NEXT_INSN (insn))
4126 free_INSN_LIST_list (&LOG_LINKS (insn));
4130 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4131 correspond to the hard registers, if any, set in that map. This
4132 could be done far more efficiently by having all sorts of special-cases
4133 with moving single words, but probably isn't worth the trouble. */
4136 reg_set_to_hard_reg_set (to, from)
4142 EXECUTE_IF_SET_IN_BITMAP
4145 if (i >= FIRST_PSEUDO_REGISTER)
4147 SET_HARD_REG_BIT (*to, i);