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 #define EH_USES(REGNO) 0
174 #ifdef HAVE_conditional_execution
175 #ifndef REVERSE_CONDEXEC_PREDICATES_P
176 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y))
180 /* Nonzero if the second flow pass has completed. */
183 /* Maximum register number used in this function, plus one. */
187 /* Indexed by n, giving various register information */
189 varray_type reg_n_info;
191 /* Size of a regset for the current function,
192 in (1) bytes and (2) elements. */
197 /* Regset of regs live when calls to `setjmp'-like functions happen. */
198 /* ??? Does this exist only for the setjmp-clobbered warning message? */
200 regset regs_live_at_setjmp;
202 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
203 that have to go in the same hard reg.
204 The first two regs in the list are a pair, and the next two
205 are another pair, etc. */
208 /* Callback that determines if it's ok for a function to have no
209 noreturn attribute. */
210 int (*lang_missing_noreturn_ok_p) PARAMS ((tree));
212 /* Set of registers that may be eliminable. These are handled specially
213 in updating regs_ever_live. */
215 static HARD_REG_SET elim_reg_set;
217 /* Holds information for tracking conditional register life information. */
218 struct reg_cond_life_info
220 /* A boolean expression of conditions under which a register is dead. */
222 /* Conditions under which a register is dead at the basic block end. */
225 /* A boolean expression of conditions under which a register has been
229 /* ??? Could store mask of bytes that are dead, so that we could finally
230 track lifetimes of multi-word registers accessed via subregs. */
233 /* For use in communicating between propagate_block and its subroutines.
234 Holds all information needed to compute life and def-use information. */
236 struct propagate_block_info
238 /* The basic block we're considering. */
241 /* Bit N is set if register N is conditionally or unconditionally live. */
244 /* Bit N is set if register N is set this insn. */
247 /* Element N is the next insn that uses (hard or pseudo) register N
248 within the current basic block; or zero, if there is no such insn. */
251 /* Contains a list of all the MEMs we are tracking for dead store
255 /* If non-null, record the set of registers set unconditionally in the
259 /* If non-null, record the set of registers set conditionally in the
261 regset cond_local_set;
263 #ifdef HAVE_conditional_execution
264 /* Indexed by register number, holds a reg_cond_life_info for each
265 register that is not unconditionally live or dead. */
266 splay_tree reg_cond_dead;
268 /* Bit N is set if register N is in an expression in reg_cond_dead. */
272 /* The length of mem_set_list. */
273 int mem_set_list_len;
275 /* Non-zero if the value of CC0 is live. */
278 /* Flags controling the set of information propagate_block collects. */
282 /* Maximum length of pbi->mem_set_list before we start dropping
283 new elements on the floor. */
284 #define MAX_MEM_SET_LIST_LEN 100
286 /* Forward declarations */
287 static int verify_wide_reg_1 PARAMS ((rtx *, void *));
288 static void verify_wide_reg PARAMS ((int, basic_block));
289 static void verify_local_live_at_start PARAMS ((regset, basic_block));
290 static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *));
291 static void notice_stack_pointer_modification PARAMS ((rtx));
292 static void mark_reg PARAMS ((rtx, void *));
293 static void mark_regs_live_at_end PARAMS ((regset));
294 static int set_phi_alternative_reg PARAMS ((rtx, int, int, void *));
295 static void calculate_global_regs_live PARAMS ((sbitmap, sbitmap, int));
296 static void propagate_block_delete_insn PARAMS ((basic_block, rtx));
297 static rtx propagate_block_delete_libcall PARAMS ((rtx, rtx));
298 static int insn_dead_p PARAMS ((struct propagate_block_info *,
300 static int libcall_dead_p PARAMS ((struct propagate_block_info *,
302 static void mark_set_regs PARAMS ((struct propagate_block_info *,
304 static void mark_set_1 PARAMS ((struct propagate_block_info *,
305 enum rtx_code, rtx, rtx,
307 static int find_regno_partial PARAMS ((rtx *, void *));
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 add_to_mem_set_list PARAMS ((struct propagate_block_info *,
338 static void invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *,
340 static void invalidate_mems_from_set PARAMS ((struct propagate_block_info *,
342 static void delete_dead_jumptables PARAMS ((void));
343 static void clear_log_links PARAMS ((sbitmap));
347 check_function_return_warnings ()
349 if (warn_missing_noreturn
350 && !TREE_THIS_VOLATILE (cfun->decl)
351 && EXIT_BLOCK_PTR->pred == NULL
352 && (lang_missing_noreturn_ok_p
353 && !lang_missing_noreturn_ok_p (cfun->decl)))
354 warning ("function might be possible candidate for attribute `noreturn'");
356 /* If we have a path to EXIT, then we do return. */
357 if (TREE_THIS_VOLATILE (cfun->decl)
358 && EXIT_BLOCK_PTR->pred != NULL)
359 warning ("`noreturn' function does return");
361 /* If the clobber_return_insn appears in some basic block, then we
362 do reach the end without returning a value. */
363 else if (warn_return_type
364 && cfun->x_clobber_return_insn != NULL
365 && EXIT_BLOCK_PTR->pred != NULL)
367 int max_uid = get_max_uid ();
369 /* If clobber_return_insn was excised by jump1, then renumber_insns
370 can make max_uid smaller than the number still recorded in our rtx.
371 That's fine, since this is a quick way of verifying that the insn
372 is no longer in the chain. */
373 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
375 /* Recompute insn->block mapping, since the initial mapping is
376 set before we delete unreachable blocks. */
377 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL)
378 warning ("control reaches end of non-void function");
383 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
384 note associated with the BLOCK. */
387 first_insn_after_basic_block_note (block)
392 /* Get the first instruction in the block. */
395 if (insn == NULL_RTX)
397 if (GET_CODE (insn) == CODE_LABEL)
398 insn = NEXT_INSN (insn);
399 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
402 return NEXT_INSN (insn);
405 /* Perform data flow analysis.
406 F is the first insn of the function; FLAGS is a set of PROP_* flags
407 to be used in accumulating flow info. */
410 life_analysis (f, file, flags)
415 #ifdef ELIMINABLE_REGS
417 static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS;
420 /* Record which registers will be eliminated. We use this in
423 CLEAR_HARD_REG_SET (elim_reg_set);
425 #ifdef ELIMINABLE_REGS
426 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
427 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
429 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
433 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES);
435 /* The post-reload life analysis have (on a global basis) the same
436 registers live as was computed by reload itself. elimination
437 Otherwise offsets and such may be incorrect.
439 Reload will make some registers as live even though they do not
442 We don't want to create new auto-incs after reload, since they
443 are unlikely to be useful and can cause problems with shared
445 if (reload_completed)
446 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
448 /* We want alias analysis information for local dead store elimination. */
449 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
450 init_alias_analysis ();
452 /* Always remove no-op moves. Do this before other processing so
453 that we don't have to keep re-scanning them. */
454 delete_noop_moves (f);
455 purge_all_dead_edges (false);
457 /* Some targets can emit simpler epilogues if they know that sp was
458 not ever modified during the function. After reload, of course,
459 we've already emitted the epilogue so there's no sense searching. */
460 if (! reload_completed)
461 notice_stack_pointer_modification (f);
463 /* Allocate and zero out data structures that will record the
464 data from lifetime analysis. */
465 allocate_reg_life_data ();
466 allocate_bb_life_data ();
468 /* Find the set of registers live on function exit. */
469 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
471 /* "Update" life info from zero. It'd be nice to begin the
472 relaxation with just the exit and noreturn blocks, but that set
473 is not immediately handy. */
475 if (flags & PROP_REG_INFO)
476 memset (regs_ever_live, 0, sizeof (regs_ever_live));
477 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
480 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
481 end_alias_analysis ();
484 dump_flow_info (file);
486 free_basic_block_vars (1);
488 #ifdef ENABLE_CHECKING
492 /* Search for any REG_LABEL notes which reference deleted labels. */
493 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
495 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
497 if (inote && GET_CODE (inote) == NOTE_INSN_DELETED_LABEL)
502 /* Removing dead insns should've made jumptables really dead. */
503 delete_dead_jumptables ();
506 /* A subroutine of verify_wide_reg, called through for_each_rtx.
507 Search for REGNO. If found, return 2 if it is not wider than
511 verify_wide_reg_1 (px, pregno)
516 unsigned int regno = *(int *) pregno;
518 if (GET_CODE (x) == REG && REGNO (x) == regno)
520 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
527 /* A subroutine of verify_local_live_at_start. Search through insns
528 of BB looking for register REGNO. */
531 verify_wide_reg (regno, bb)
535 rtx head = bb->head, end = bb->end;
541 int r = for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no);
549 head = NEXT_INSN (head);
554 fprintf (rtl_dump_file, "Register %d died unexpectedly.\n", regno);
555 dump_bb (bb, rtl_dump_file);
560 /* A subroutine of update_life_info. Verify that there are no untoward
561 changes in live_at_start during a local update. */
564 verify_local_live_at_start (new_live_at_start, bb)
565 regset new_live_at_start;
568 if (reload_completed)
570 /* After reload, there are no pseudos, nor subregs of multi-word
571 registers. The regsets should exactly match. */
572 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
576 fprintf (rtl_dump_file,
577 "live_at_start mismatch in bb %d, aborting\nNew:\n",
579 debug_bitmap_file (rtl_dump_file, new_live_at_start);
580 fputs ("Old:\n", rtl_dump_file);
581 dump_bb (bb, rtl_dump_file);
590 /* Find the set of changed registers. */
591 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
593 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
595 /* No registers should die. */
596 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
600 fprintf (rtl_dump_file,
601 "Register %d died unexpectedly.\n", i);
602 dump_bb (bb, rtl_dump_file);
607 /* Verify that the now-live register is wider than word_mode. */
608 verify_wide_reg (i, bb);
613 /* Updates life information starting with the basic blocks set in BLOCKS.
614 If BLOCKS is null, consider it to be the universal set.
616 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
617 we are only expecting local modifications to basic blocks. If we find
618 extra registers live at the beginning of a block, then we either killed
619 useful data, or we have a broken split that wants data not provided.
620 If we find registers removed from live_at_start, that means we have
621 a broken peephole that is killing a register it shouldn't.
623 ??? This is not true in one situation -- when a pre-reload splitter
624 generates subregs of a multi-word pseudo, current life analysis will
625 lose the kill. So we _can_ have a pseudo go live. How irritating.
627 Including PROP_REG_INFO does not properly refresh regs_ever_live
628 unless the caller resets it to zero. */
631 update_life_info (blocks, extent, prop_flags)
633 enum update_life_extent extent;
637 regset_head tmp_head;
639 int stabilized_prop_flags = prop_flags;
641 tmp = INITIALIZE_REG_SET (tmp_head);
643 timevar_push ((extent == UPDATE_LIFE_LOCAL || blocks)
644 ? TV_LIFE_UPDATE : TV_LIFE);
646 /* Changes to the CFG are only allowed when
647 doing a global update for the entire CFG. */
648 if ((prop_flags & PROP_ALLOW_CFG_CHANGES)
649 && (extent == UPDATE_LIFE_LOCAL || blocks))
652 /* Clear log links in case we are asked to (re)compute them. */
653 if (prop_flags & PROP_LOG_LINKS)
654 clear_log_links (blocks);
656 /* For a global update, we go through the relaxation process again. */
657 if (extent != UPDATE_LIFE_LOCAL)
663 calculate_global_regs_live (blocks, blocks,
664 prop_flags & (PROP_SCAN_DEAD_CODE
665 | PROP_ALLOW_CFG_CHANGES));
667 if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
668 != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
671 /* Removing dead code may allow the CFG to be simplified which
672 in turn may allow for further dead code detection / removal. */
673 for (i = n_basic_blocks - 1; i >= 0; --i)
675 basic_block bb = BASIC_BLOCK (i);
677 COPY_REG_SET (tmp, bb->global_live_at_end);
678 changed |= propagate_block (bb, tmp, NULL, NULL,
679 prop_flags & (PROP_SCAN_DEAD_CODE
680 | PROP_KILL_DEAD_CODE));
683 /* Don't pass PROP_SCAN_DEAD_CODE or PROP_KILL_DEAD_CODE to
684 subsequent propagate_block calls, since removing or acting as
685 removing dead code can affect global register liveness, which
686 is supposed to be finalized for this call after this loop. */
687 stabilized_prop_flags
688 &= ~(PROP_SCAN_DEAD_CODE | PROP_KILL_DEAD_CODE);
693 /* We repeat regardless of what cleanup_cfg says. If there were
694 instructions deleted above, that might have been only a
695 partial improvement (see MAX_MEM_SET_LIST_LEN usage).
696 Further improvement may be possible. */
697 cleanup_cfg (CLEANUP_EXPENSIVE);
700 /* If asked, remove notes from the blocks we'll update. */
701 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
702 count_or_remove_death_notes (blocks, 1);
707 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
709 basic_block bb = BASIC_BLOCK (i);
711 COPY_REG_SET (tmp, bb->global_live_at_end);
712 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags);
714 if (extent == UPDATE_LIFE_LOCAL)
715 verify_local_live_at_start (tmp, bb);
720 for (i = n_basic_blocks - 1; i >= 0; --i)
722 basic_block bb = BASIC_BLOCK (i);
724 COPY_REG_SET (tmp, bb->global_live_at_end);
726 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags);
728 if (extent == UPDATE_LIFE_LOCAL)
729 verify_local_live_at_start (tmp, bb);
735 if (prop_flags & PROP_REG_INFO)
737 /* The only pseudos that are live at the beginning of the function
738 are those that were not set anywhere in the function. local-alloc
739 doesn't know how to handle these correctly, so mark them as not
740 local to any one basic block. */
741 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
742 FIRST_PSEUDO_REGISTER, i,
743 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
745 /* We have a problem with any pseudoreg that lives across the setjmp.
746 ANSI says that if a user variable does not change in value between
747 the setjmp and the longjmp, then the longjmp preserves it. This
748 includes longjmp from a place where the pseudo appears dead.
749 (In principle, the value still exists if it is in scope.)
750 If the pseudo goes in a hard reg, some other value may occupy
751 that hard reg where this pseudo is dead, thus clobbering the pseudo.
752 Conclusion: such a pseudo must not go in a hard reg. */
753 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
754 FIRST_PSEUDO_REGISTER, i,
756 if (regno_reg_rtx[i] != 0)
758 REG_LIVE_LENGTH (i) = -1;
759 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
763 timevar_pop ((extent == UPDATE_LIFE_LOCAL || blocks)
764 ? TV_LIFE_UPDATE : TV_LIFE);
767 /* Free the variables allocated by find_basic_blocks.
769 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
772 free_basic_block_vars (keep_head_end_p)
775 if (! keep_head_end_p)
777 if (basic_block_info)
780 VARRAY_FREE (basic_block_info);
784 ENTRY_BLOCK_PTR->aux = NULL;
785 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
786 EXIT_BLOCK_PTR->aux = NULL;
787 EXIT_BLOCK_PTR->global_live_at_start = NULL;
791 /* Delete any insns that copy a register to itself. */
794 delete_noop_moves (f)
795 rtx f ATTRIBUTE_UNUSED;
801 for (i = 0; i < n_basic_blocks; i++)
803 bb = BASIC_BLOCK (i);
804 for (insn = bb->head; insn != NEXT_INSN (bb->end); insn = next)
806 next = NEXT_INSN (insn);
807 if (INSN_P (insn) && noop_move_p (insn))
811 /* If we're about to remove the first insn of a libcall
812 then move the libcall note to the next real insn and
813 update the retval note. */
814 if ((note = find_reg_note (insn, REG_LIBCALL, NULL_RTX))
815 && XEXP (note, 0) != insn)
817 rtx new_libcall_insn = next_real_insn (insn);
818 rtx retval_note = find_reg_note (XEXP (note, 0),
819 REG_RETVAL, NULL_RTX);
820 REG_NOTES (new_libcall_insn)
821 = gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0),
822 REG_NOTES (new_libcall_insn));
823 XEXP (retval_note, 0) = new_libcall_insn;
826 /* Do not call delete_insn here since that may change
827 the basic block boundaries which upsets some callers. */
828 PUT_CODE (insn, NOTE);
829 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
830 NOTE_SOURCE_FILE (insn) = 0;
836 /* Delete any jump tables never referenced. We can't delete them at the
837 time of removing tablejump insn as they are referenced by the preceding
838 insns computing the destination, so we delay deleting and garbagecollect
839 them once life information is computed. */
841 delete_dead_jumptables ()
844 for (insn = get_insns (); insn; insn = next)
846 next = NEXT_INSN (insn);
847 if (GET_CODE (insn) == CODE_LABEL
848 && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
849 && GET_CODE (next) == JUMP_INSN
850 && (GET_CODE (PATTERN (next)) == ADDR_VEC
851 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
854 fprintf (rtl_dump_file, "Dead jumptable %i removed\n", INSN_UID (insn));
855 delete_insn (NEXT_INSN (insn));
857 next = NEXT_INSN (next);
862 /* Determine if the stack pointer is constant over the life of the function.
863 Only useful before prologues have been emitted. */
866 notice_stack_pointer_modification_1 (x, pat, data)
868 rtx pat ATTRIBUTE_UNUSED;
869 void *data ATTRIBUTE_UNUSED;
871 if (x == stack_pointer_rtx
872 /* The stack pointer is only modified indirectly as the result
873 of a push until later in flow. See the comments in rtl.texi
874 regarding Embedded Side-Effects on Addresses. */
875 || (GET_CODE (x) == MEM
876 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
877 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
878 current_function_sp_is_unchanging = 0;
882 notice_stack_pointer_modification (f)
887 /* Assume that the stack pointer is unchanging if alloca hasn't
889 current_function_sp_is_unchanging = !current_function_calls_alloca;
890 if (! current_function_sp_is_unchanging)
893 for (insn = f; insn; insn = NEXT_INSN (insn))
897 /* Check if insn modifies the stack pointer. */
898 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
900 if (! current_function_sp_is_unchanging)
906 /* Mark a register in SET. Hard registers in large modes get all
907 of their component registers set as well. */
914 regset set = (regset) xset;
915 int regno = REGNO (reg);
917 if (GET_MODE (reg) == BLKmode)
920 SET_REGNO_REG_SET (set, regno);
921 if (regno < FIRST_PSEUDO_REGISTER)
923 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
925 SET_REGNO_REG_SET (set, regno + n);
929 /* Mark those regs which are needed at the end of the function as live
930 at the end of the last basic block. */
933 mark_regs_live_at_end (set)
938 /* If exiting needs the right stack value, consider the stack pointer
939 live at the end of the function. */
940 if ((HAVE_epilogue && reload_completed)
941 || ! EXIT_IGNORE_STACK
942 || (! FRAME_POINTER_REQUIRED
943 && ! current_function_calls_alloca
944 && flag_omit_frame_pointer)
945 || current_function_sp_is_unchanging)
947 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
950 /* Mark the frame pointer if needed at the end of the function. If
951 we end up eliminating it, it will be removed from the live list
952 of each basic block by reload. */
954 if (! reload_completed || frame_pointer_needed)
956 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
957 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
958 /* If they are different, also mark the hard frame pointer as live. */
959 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
960 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
964 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
965 /* Many architectures have a GP register even without flag_pic.
966 Assume the pic register is not in use, or will be handled by
967 other means, if it is not fixed. */
968 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
969 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
970 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
973 /* Mark all global registers, and all registers used by the epilogue
974 as being live at the end of the function since they may be
975 referenced by our caller. */
976 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
977 if (global_regs[i] || EPILOGUE_USES (i))
978 SET_REGNO_REG_SET (set, i);
980 if (HAVE_epilogue && reload_completed)
982 /* Mark all call-saved registers that we actually used. */
983 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
984 if (regs_ever_live[i] && ! LOCAL_REGNO (i)
985 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
986 SET_REGNO_REG_SET (set, i);
989 #ifdef EH_RETURN_DATA_REGNO
990 /* Mark the registers that will contain data for the handler. */
991 if (reload_completed && current_function_calls_eh_return)
994 unsigned regno = EH_RETURN_DATA_REGNO(i);
995 if (regno == INVALID_REGNUM)
997 SET_REGNO_REG_SET (set, regno);
1000 #ifdef EH_RETURN_STACKADJ_RTX
1001 if ((! HAVE_epilogue || ! reload_completed)
1002 && current_function_calls_eh_return)
1004 rtx tmp = EH_RETURN_STACKADJ_RTX;
1005 if (tmp && REG_P (tmp))
1006 mark_reg (tmp, set);
1009 #ifdef EH_RETURN_HANDLER_RTX
1010 if ((! HAVE_epilogue || ! reload_completed)
1011 && current_function_calls_eh_return)
1013 rtx tmp = EH_RETURN_HANDLER_RTX;
1014 if (tmp && REG_P (tmp))
1015 mark_reg (tmp, set);
1019 /* Mark function return value. */
1020 diddle_return_value (mark_reg, set);
1023 /* Callback function for for_each_successor_phi. DATA is a regset.
1024 Sets the SRC_REGNO, the regno of the phi alternative for phi node
1025 INSN, in the regset. */
1028 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
1029 rtx insn ATTRIBUTE_UNUSED;
1030 int dest_regno ATTRIBUTE_UNUSED;
1034 regset live = (regset) data;
1035 SET_REGNO_REG_SET (live, src_regno);
1039 /* Propagate global life info around the graph of basic blocks. Begin
1040 considering blocks with their corresponding bit set in BLOCKS_IN.
1041 If BLOCKS_IN is null, consider it the universal set.
1043 BLOCKS_OUT is set for every block that was changed. */
1046 calculate_global_regs_live (blocks_in, blocks_out, flags)
1047 sbitmap blocks_in, blocks_out;
1050 basic_block *queue, *qhead, *qtail, *qend;
1051 regset tmp, new_live_at_end, call_used;
1052 regset_head tmp_head, call_used_head;
1053 regset_head new_live_at_end_head;
1056 tmp = INITIALIZE_REG_SET (tmp_head);
1057 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
1058 call_used = INITIALIZE_REG_SET (call_used_head);
1060 /* Inconveniently, this is only readily available in hard reg set form. */
1061 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
1062 if (call_used_regs[i])
1063 SET_REGNO_REG_SET (call_used, i);
1065 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1066 because the `head == tail' style test for an empty queue doesn't
1067 work with a full queue. */
1068 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
1070 qhead = qend = queue + n_basic_blocks + 2;
1072 /* Queue the blocks set in the initial mask. Do this in reverse block
1073 number order so that we are more likely for the first round to do
1074 useful work. We use AUX non-null to flag that the block is queued. */
1077 /* Clear out the garbage that might be hanging out in bb->aux. */
1078 for (i = n_basic_blocks - 1; i >= 0; --i)
1079 BASIC_BLOCK (i)->aux = NULL;
1081 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
1083 basic_block bb = BASIC_BLOCK (i);
1090 for (i = 0; i < n_basic_blocks; ++i)
1092 basic_block bb = BASIC_BLOCK (i);
1098 /* We clean aux when we remove the initially-enqueued bbs, but we
1099 don't enqueue ENTRY and EXIT initially, so clean them upfront and
1101 ENTRY_BLOCK_PTR->aux = EXIT_BLOCK_PTR->aux = NULL;
1104 sbitmap_zero (blocks_out);
1106 /* We work through the queue until there are no more blocks. What
1107 is live at the end of this block is precisely the union of what
1108 is live at the beginning of all its successors. So, we set its
1109 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1110 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1111 this block by walking through the instructions in this block in
1112 reverse order and updating as we go. If that changed
1113 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1114 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1116 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1117 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1118 must either be live at the end of the block, or used within the
1119 block. In the latter case, it will certainly never disappear
1120 from GLOBAL_LIVE_AT_START. In the former case, the register
1121 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1122 for one of the successor blocks. By induction, that cannot
1124 while (qhead != qtail)
1126 int rescan, changed;
1135 /* Begin by propagating live_at_start from the successor blocks. */
1136 CLEAR_REG_SET (new_live_at_end);
1139 for (e = bb->succ; e; e = e->succ_next)
1141 basic_block sb = e->dest;
1143 /* Call-clobbered registers die across exception and
1145 /* ??? Abnormal call edges ignored for the moment, as this gets
1146 confused by sibling call edges, which crashes reg-stack. */
1147 if (e->flags & EDGE_EH)
1149 bitmap_operation (tmp, sb->global_live_at_start,
1150 call_used, BITMAP_AND_COMPL);
1151 IOR_REG_SET (new_live_at_end, tmp);
1154 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
1156 /* If a target saves one register in another (instead of on
1157 the stack) the save register will need to be live for EH. */
1158 if (e->flags & EDGE_EH)
1159 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1161 SET_REGNO_REG_SET (new_live_at_end, i);
1165 /* This might be a noreturn function that throws. And
1166 even if it isn't, getting the unwind info right helps
1168 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1170 SET_REGNO_REG_SET (new_live_at_end, i);
1173 /* The all-important stack pointer must always be live. */
1174 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
1176 /* Before reload, there are a few registers that must be forced
1177 live everywhere -- which might not already be the case for
1178 blocks within infinite loops. */
1179 if (! reload_completed)
1181 /* Any reference to any pseudo before reload is a potential
1182 reference of the frame pointer. */
1183 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
1185 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1186 /* Pseudos with argument area equivalences may require
1187 reloading via the argument pointer. */
1188 if (fixed_regs[ARG_POINTER_REGNUM])
1189 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
1192 /* Any constant, or pseudo with constant equivalences, may
1193 require reloading from memory using the pic register. */
1194 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
1195 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
1196 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
1199 /* Regs used in phi nodes are not included in
1200 global_live_at_start, since they are live only along a
1201 particular edge. Set those regs that are live because of a
1202 phi node alternative corresponding to this particular block. */
1204 for_each_successor_phi (bb, &set_phi_alternative_reg,
1207 if (bb == ENTRY_BLOCK_PTR)
1209 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1213 /* On our first pass through this block, we'll go ahead and continue.
1214 Recognize first pass by local_set NULL. On subsequent passes, we
1215 get to skip out early if live_at_end wouldn't have changed. */
1217 if (bb->local_set == NULL)
1219 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1220 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1225 /* If any bits were removed from live_at_end, we'll have to
1226 rescan the block. This wouldn't be necessary if we had
1227 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1228 local_live is really dependent on live_at_end. */
1229 CLEAR_REG_SET (tmp);
1230 rescan = bitmap_operation (tmp, bb->global_live_at_end,
1231 new_live_at_end, BITMAP_AND_COMPL);
1235 /* If any of the registers in the new live_at_end set are
1236 conditionally set in this basic block, we must rescan.
1237 This is because conditional lifetimes at the end of the
1238 block do not just take the live_at_end set into account,
1239 but also the liveness at the start of each successor
1240 block. We can miss changes in those sets if we only
1241 compare the new live_at_end against the previous one. */
1242 CLEAR_REG_SET (tmp);
1243 rescan = bitmap_operation (tmp, new_live_at_end,
1244 bb->cond_local_set, BITMAP_AND);
1249 /* Find the set of changed bits. Take this opportunity
1250 to notice that this set is empty and early out. */
1251 CLEAR_REG_SET (tmp);
1252 changed = bitmap_operation (tmp, bb->global_live_at_end,
1253 new_live_at_end, BITMAP_XOR);
1257 /* If any of the changed bits overlap with local_set,
1258 we'll have to rescan the block. Detect overlap by
1259 the AND with ~local_set turning off bits. */
1260 rescan = bitmap_operation (tmp, tmp, bb->local_set,
1265 /* Let our caller know that BB changed enough to require its
1266 death notes updated. */
1268 SET_BIT (blocks_out, bb->index);
1272 /* Add to live_at_start the set of all registers in
1273 new_live_at_end that aren't in the old live_at_end. */
1275 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
1277 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1279 changed = bitmap_operation (bb->global_live_at_start,
1280 bb->global_live_at_start,
1287 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1289 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1290 into live_at_start. */
1291 propagate_block (bb, new_live_at_end, bb->local_set,
1292 bb->cond_local_set, flags);
1294 /* If live_at start didn't change, no need to go farther. */
1295 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
1298 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
1301 /* Queue all predecessors of BB so that we may re-examine
1302 their live_at_end. */
1303 for (e = bb->pred; e; e = e->pred_next)
1305 basic_block pb = e->src;
1306 if (pb->aux == NULL)
1317 FREE_REG_SET (new_live_at_end);
1318 FREE_REG_SET (call_used);
1322 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
1324 basic_block bb = BASIC_BLOCK (i);
1325 FREE_REG_SET (bb->local_set);
1326 FREE_REG_SET (bb->cond_local_set);
1331 for (i = n_basic_blocks - 1; i >= 0; --i)
1333 basic_block bb = BASIC_BLOCK (i);
1334 FREE_REG_SET (bb->local_set);
1335 FREE_REG_SET (bb->cond_local_set);
1343 /* This structure is used to pass parameters to an from the
1344 the function find_regno_partial(). It is used to pass in the
1345 register number we are looking, as well as to return any rtx
1349 unsigned regno_to_find;
1351 } find_regno_partial_param;
1354 /* Find the rtx for the reg numbers specified in 'data' if it is
1355 part of an expression which only uses part of the register. Return
1356 it in the structure passed in. */
1358 find_regno_partial (ptr, data)
1362 find_regno_partial_param *param = (find_regno_partial_param *)data;
1363 unsigned reg = param->regno_to_find;
1364 param->retval = NULL_RTX;
1366 if (*ptr == NULL_RTX)
1369 switch (GET_CODE (*ptr))
1373 case STRICT_LOW_PART:
1374 if (GET_CODE (XEXP (*ptr, 0)) == REG && REGNO (XEXP (*ptr, 0)) == reg)
1376 param->retval = XEXP (*ptr, 0);
1382 if (GET_CODE (SUBREG_REG (*ptr)) == REG
1383 && REGNO (SUBREG_REG (*ptr)) == reg)
1385 param->retval = SUBREG_REG (*ptr);
1397 /* Process all immediate successors of the entry block looking for pseudo
1398 registers which are live on entry. Find all of those whose first
1399 instance is a partial register reference of some kind, and initialize
1400 them to 0 after the entry block. This will prevent bit sets within
1401 registers whose value is unknown, and may contain some kind of sticky
1402 bits we don't want. */
1405 initialize_uninitialized_subregs ()
1409 int reg, did_something = 0;
1410 find_regno_partial_param param;
1412 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
1414 basic_block bb = e->dest;
1415 regset map = bb->global_live_at_start;
1416 EXECUTE_IF_SET_IN_REG_SET (map,
1417 FIRST_PSEUDO_REGISTER, reg,
1419 int uid = REGNO_FIRST_UID (reg);
1422 /* Find an insn which mentions the register we are looking for.
1423 Its preferable to have an instance of the register's rtl since
1424 there may be various flags set which we need to duplicate.
1425 If we can't find it, its probably an automatic whose initial
1426 value doesn't matter, or hopefully something we don't care about. */
1427 for (i = get_insns (); i && INSN_UID (i) != uid; i = NEXT_INSN (i))
1431 /* Found the insn, now get the REG rtx, if we can. */
1432 param.regno_to_find = reg;
1433 for_each_rtx (&i, find_regno_partial, ¶m);
1434 if (param.retval != NULL_RTX)
1436 insn = gen_move_insn (param.retval,
1437 CONST0_RTX (GET_MODE (param.retval)));
1438 insert_insn_on_edge (insn, e);
1446 commit_edge_insertions ();
1447 return did_something;
1451 /* Subroutines of life analysis. */
1453 /* Allocate the permanent data structures that represent the results
1454 of life analysis. Not static since used also for stupid life analysis. */
1457 allocate_bb_life_data ()
1461 for (i = 0; i < n_basic_blocks; i++)
1463 basic_block bb = BASIC_BLOCK (i);
1465 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1466 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1469 ENTRY_BLOCK_PTR->global_live_at_end
1470 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1471 EXIT_BLOCK_PTR->global_live_at_start
1472 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1474 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1478 allocate_reg_life_data ()
1482 max_regno = max_reg_num ();
1484 /* Recalculate the register space, in case it has grown. Old style
1485 vector oriented regsets would set regset_{size,bytes} here also. */
1486 allocate_reg_info (max_regno, FALSE, FALSE);
1488 /* Reset all the data we'll collect in propagate_block and its
1490 for (i = 0; i < max_regno; i++)
1494 REG_N_DEATHS (i) = 0;
1495 REG_N_CALLS_CROSSED (i) = 0;
1496 REG_LIVE_LENGTH (i) = 0;
1497 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
1501 /* Delete dead instructions for propagate_block. */
1504 propagate_block_delete_insn (bb, insn)
1508 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
1511 /* If the insn referred to a label, and that label was attached to
1512 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1513 pretty much mandatory to delete it, because the ADDR_VEC may be
1514 referencing labels that no longer exist.
1516 INSN may reference a deleted label, particularly when a jump
1517 table has been optimized into a direct jump. There's no
1518 real good way to fix up the reference to the deleted label
1519 when the label is deleted, so we just allow it here.
1521 After dead code elimination is complete, we do search for
1522 any REG_LABEL notes which reference deleted labels as a
1525 if (inote && GET_CODE (inote) == CODE_LABEL)
1527 rtx label = XEXP (inote, 0);
1530 /* The label may be forced if it has been put in the constant
1531 pool. If that is the only use we must discard the table
1532 jump following it, but not the label itself. */
1533 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
1534 && (next = next_nonnote_insn (label)) != NULL
1535 && GET_CODE (next) == JUMP_INSN
1536 && (GET_CODE (PATTERN (next)) == ADDR_VEC
1537 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
1539 rtx pat = PATTERN (next);
1540 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
1541 int len = XVECLEN (pat, diff_vec_p);
1544 for (i = 0; i < len; i++)
1545 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
1551 if (bb->end == insn)
1555 purge_dead_edges (bb);
1558 /* Delete dead libcalls for propagate_block. Return the insn
1559 before the libcall. */
1562 propagate_block_delete_libcall ( insn, note)
1565 rtx first = XEXP (note, 0);
1566 rtx before = PREV_INSN (first);
1568 delete_insn_chain (first, insn);
1572 /* Update the life-status of regs for one insn. Return the previous insn. */
1575 propagate_one_insn (pbi, insn)
1576 struct propagate_block_info *pbi;
1579 rtx prev = PREV_INSN (insn);
1580 int flags = pbi->flags;
1581 int insn_is_dead = 0;
1582 int libcall_is_dead = 0;
1586 if (! INSN_P (insn))
1589 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1590 if (flags & PROP_SCAN_DEAD_CODE)
1592 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
1593 libcall_is_dead = (insn_is_dead && note != 0
1594 && libcall_dead_p (pbi, note, insn));
1597 /* If an instruction consists of just dead store(s) on final pass,
1599 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
1601 /* If we're trying to delete a prologue or epilogue instruction
1602 that isn't flagged as possibly being dead, something is wrong.
1603 But if we are keeping the stack pointer depressed, we might well
1604 be deleting insns that are used to compute the amount to update
1605 it by, so they are fine. */
1606 if (reload_completed
1607 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1608 && (TYPE_RETURNS_STACK_DEPRESSED
1609 (TREE_TYPE (current_function_decl))))
1610 && (((HAVE_epilogue || HAVE_prologue)
1611 && prologue_epilogue_contains (insn))
1612 || (HAVE_sibcall_epilogue
1613 && sibcall_epilogue_contains (insn)))
1614 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
1615 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn);
1617 /* Record sets. Do this even for dead instructions, since they
1618 would have killed the values if they hadn't been deleted. */
1619 mark_set_regs (pbi, PATTERN (insn), insn);
1621 /* CC0 is now known to be dead. Either this insn used it,
1622 in which case it doesn't anymore, or clobbered it,
1623 so the next insn can't use it. */
1626 if (libcall_is_dead)
1627 prev = propagate_block_delete_libcall ( insn, note);
1631 /* If INSN contains a RETVAL note and is dead, but the libcall
1632 as a whole is not dead, then we want to remove INSN, but
1633 not the whole libcall sequence.
1635 However, we need to also remove the dangling REG_LIBCALL
1636 note so that we do not have mis-matched LIBCALL/RETVAL
1637 notes. In theory we could find a new location for the
1638 REG_RETVAL note, but it hardly seems worth the effort.
1640 NOTE at this point will be the RETVAL note if it exists. */
1646 = find_reg_note (XEXP (note, 0), REG_LIBCALL, NULL_RTX);
1647 remove_note (XEXP (note, 0), libcall_note);
1650 /* Similarly if INSN contains a LIBCALL note, remove the
1651 dangling REG_RETVAL note. */
1652 note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
1658 = find_reg_note (XEXP (note, 0), REG_RETVAL, NULL_RTX);
1659 remove_note (XEXP (note, 0), retval_note);
1662 /* Now delete INSN. */
1663 propagate_block_delete_insn (pbi->bb, insn);
1669 /* See if this is an increment or decrement that can be merged into
1670 a following memory address. */
1673 rtx x = single_set (insn);
1675 /* Does this instruction increment or decrement a register? */
1676 if ((flags & PROP_AUTOINC)
1678 && GET_CODE (SET_DEST (x)) == REG
1679 && (GET_CODE (SET_SRC (x)) == PLUS
1680 || GET_CODE (SET_SRC (x)) == MINUS)
1681 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1682 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1683 /* Ok, look for a following memory ref we can combine with.
1684 If one is found, change the memory ref to a PRE_INC
1685 or PRE_DEC, cancel this insn, and return 1.
1686 Return 0 if nothing has been done. */
1687 && try_pre_increment_1 (pbi, insn))
1690 #endif /* AUTO_INC_DEC */
1692 CLEAR_REG_SET (pbi->new_set);
1694 /* If this is not the final pass, and this insn is copying the value of
1695 a library call and it's dead, don't scan the insns that perform the
1696 library call, so that the call's arguments are not marked live. */
1697 if (libcall_is_dead)
1699 /* Record the death of the dest reg. */
1700 mark_set_regs (pbi, PATTERN (insn), insn);
1702 insn = XEXP (note, 0);
1703 return PREV_INSN (insn);
1705 else if (GET_CODE (PATTERN (insn)) == SET
1706 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1707 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1708 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1709 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1710 /* We have an insn to pop a constant amount off the stack.
1711 (Such insns use PLUS regardless of the direction of the stack,
1712 and any insn to adjust the stack by a constant is always a pop.)
1713 These insns, if not dead stores, have no effect on life. */
1718 /* Any regs live at the time of a call instruction must not go
1719 in a register clobbered by calls. Find all regs now live and
1720 record this for them. */
1722 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
1723 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
1724 { REG_N_CALLS_CROSSED (i)++; });
1726 /* Record sets. Do this even for dead instructions, since they
1727 would have killed the values if they hadn't been deleted. */
1728 mark_set_regs (pbi, PATTERN (insn), insn);
1730 if (GET_CODE (insn) == CALL_INSN)
1736 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1737 cond = COND_EXEC_TEST (PATTERN (insn));
1739 /* Non-constant calls clobber memory. */
1740 if (! CONST_OR_PURE_CALL_P (insn))
1742 free_EXPR_LIST_list (&pbi->mem_set_list);
1743 pbi->mem_set_list_len = 0;
1746 /* There may be extra registers to be clobbered. */
1747 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1749 note = XEXP (note, 1))
1750 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
1751 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
1752 cond, insn, pbi->flags);
1754 /* Calls change all call-used and global registers. */
1755 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1756 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1758 /* We do not want REG_UNUSED notes for these registers. */
1759 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
1761 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
1765 /* If an insn doesn't use CC0, it becomes dead since we assume
1766 that every insn clobbers it. So show it dead here;
1767 mark_used_regs will set it live if it is referenced. */
1772 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
1773 if ((flags & PROP_EQUAL_NOTES)
1774 && ((note = find_reg_note (insn, REG_EQUAL, NULL_RTX))
1775 || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX))))
1776 mark_used_regs (pbi, XEXP (note, 0), NULL_RTX, insn);
1778 /* Sometimes we may have inserted something before INSN (such as a move)
1779 when we make an auto-inc. So ensure we will scan those insns. */
1781 prev = PREV_INSN (insn);
1784 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1790 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1791 cond = COND_EXEC_TEST (PATTERN (insn));
1793 /* Calls use their arguments. */
1794 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1796 note = XEXP (note, 1))
1797 if (GET_CODE (XEXP (note, 0)) == USE)
1798 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
1801 /* The stack ptr is used (honorarily) by a CALL insn. */
1802 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
1804 /* Calls may also reference any of the global registers,
1805 so they are made live. */
1806 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1808 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
1813 /* On final pass, update counts of how many insns in which each reg
1815 if (flags & PROP_REG_INFO)
1816 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
1817 { REG_LIVE_LENGTH (i)++; });
1822 /* Initialize a propagate_block_info struct for public consumption.
1823 Note that the structure itself is opaque to this file, but that
1824 the user can use the regsets provided here. */
1826 struct propagate_block_info *
1827 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
1829 regset live, local_set, cond_local_set;
1832 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
1835 pbi->reg_live = live;
1836 pbi->mem_set_list = NULL_RTX;
1837 pbi->mem_set_list_len = 0;
1838 pbi->local_set = local_set;
1839 pbi->cond_local_set = cond_local_set;
1843 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
1844 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
1846 pbi->reg_next_use = NULL;
1848 pbi->new_set = BITMAP_XMALLOC ();
1850 #ifdef HAVE_conditional_execution
1851 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
1852 free_reg_cond_life_info);
1853 pbi->reg_cond_reg = BITMAP_XMALLOC ();
1855 /* If this block ends in a conditional branch, for each register live
1856 from one side of the branch and not the other, record the register
1857 as conditionally dead. */
1858 if (GET_CODE (bb->end) == JUMP_INSN
1859 && any_condjump_p (bb->end))
1861 regset_head diff_head;
1862 regset diff = INITIALIZE_REG_SET (diff_head);
1863 basic_block bb_true, bb_false;
1864 rtx cond_true, cond_false, set_src;
1867 /* Identify the successor blocks. */
1868 bb_true = bb->succ->dest;
1869 if (bb->succ->succ_next != NULL)
1871 bb_false = bb->succ->succ_next->dest;
1873 if (bb->succ->flags & EDGE_FALLTHRU)
1875 basic_block t = bb_false;
1879 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
1884 /* This can happen with a conditional jump to the next insn. */
1885 if (JUMP_LABEL (bb->end) != bb_true->head)
1888 /* Simplest way to do nothing. */
1892 /* Extract the condition from the branch. */
1893 set_src = SET_SRC (pc_set (bb->end));
1894 cond_true = XEXP (set_src, 0);
1895 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
1896 GET_MODE (cond_true), XEXP (cond_true, 0),
1897 XEXP (cond_true, 1));
1898 if (GET_CODE (XEXP (set_src, 1)) == PC)
1901 cond_false = cond_true;
1905 /* Compute which register lead different lives in the successors. */
1906 if (bitmap_operation (diff, bb_true->global_live_at_start,
1907 bb_false->global_live_at_start, BITMAP_XOR))
1909 rtx reg = XEXP (cond_true, 0);
1911 if (GET_CODE (reg) == SUBREG)
1912 reg = SUBREG_REG (reg);
1914 if (GET_CODE (reg) != REG)
1917 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
1919 /* For each such register, mark it conditionally dead. */
1920 EXECUTE_IF_SET_IN_REG_SET
1923 struct reg_cond_life_info *rcli;
1926 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
1928 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
1932 rcli->condition = cond;
1933 rcli->stores = const0_rtx;
1934 rcli->orig_condition = cond;
1936 splay_tree_insert (pbi->reg_cond_dead, i,
1937 (splay_tree_value) rcli);
1941 FREE_REG_SET (diff);
1945 /* If this block has no successors, any stores to the frame that aren't
1946 used later in the block are dead. So make a pass over the block
1947 recording any such that are made and show them dead at the end. We do
1948 a very conservative and simple job here. */
1950 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1951 && (TYPE_RETURNS_STACK_DEPRESSED
1952 (TREE_TYPE (current_function_decl))))
1953 && (flags & PROP_SCAN_DEAD_CODE)
1954 && (bb->succ == NULL
1955 || (bb->succ->succ_next == NULL
1956 && bb->succ->dest == EXIT_BLOCK_PTR
1957 && ! current_function_calls_eh_return)))
1960 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
1961 if (GET_CODE (insn) == INSN
1962 && (set = single_set (insn))
1963 && GET_CODE (SET_DEST (set)) == MEM)
1965 rtx mem = SET_DEST (set);
1966 rtx canon_mem = canon_rtx (mem);
1968 /* This optimization is performed by faking a store to the
1969 memory at the end of the block. This doesn't work for
1970 unchanging memories because multiple stores to unchanging
1971 memory is illegal and alias analysis doesn't consider it. */
1972 if (RTX_UNCHANGING_P (canon_mem))
1975 if (XEXP (canon_mem, 0) == frame_pointer_rtx
1976 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
1977 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
1978 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
1979 add_to_mem_set_list (pbi, canon_mem);
1986 /* Release a propagate_block_info struct. */
1989 free_propagate_block_info (pbi)
1990 struct propagate_block_info *pbi;
1992 free_EXPR_LIST_list (&pbi->mem_set_list);
1994 BITMAP_XFREE (pbi->new_set);
1996 #ifdef HAVE_conditional_execution
1997 splay_tree_delete (pbi->reg_cond_dead);
1998 BITMAP_XFREE (pbi->reg_cond_reg);
2001 if (pbi->reg_next_use)
2002 free (pbi->reg_next_use);
2007 /* Compute the registers live at the beginning of a basic block BB from
2008 those live at the end.
2010 When called, REG_LIVE contains those live at the end. On return, it
2011 contains those live at the beginning.
2013 LOCAL_SET, if non-null, will be set with all registers killed
2014 unconditionally by this basic block.
2015 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
2016 killed conditionally by this basic block. If there is any unconditional
2017 set of a register, then the corresponding bit will be set in LOCAL_SET
2018 and cleared in COND_LOCAL_SET.
2019 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
2020 case, the resulting set will be equal to the union of the two sets that
2021 would otherwise be computed.
2023 Return non-zero if an INSN is deleted (i.e. by dead code removal). */
2026 propagate_block (bb, live, local_set, cond_local_set, flags)
2030 regset cond_local_set;
2033 struct propagate_block_info *pbi;
2037 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
2039 if (flags & PROP_REG_INFO)
2043 /* Process the regs live at the end of the block.
2044 Mark them as not local to any one basic block. */
2045 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
2046 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
2049 /* Scan the block an insn at a time from end to beginning. */
2052 for (insn = bb->end;; insn = prev)
2054 /* If this is a call to `setjmp' et al, warn if any
2055 non-volatile datum is live. */
2056 if ((flags & PROP_REG_INFO)
2057 && GET_CODE (insn) == CALL_INSN
2058 && find_reg_note (insn, REG_SETJMP, NULL))
2059 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
2061 prev = propagate_one_insn (pbi, insn);
2062 changed |= NEXT_INSN (prev) != insn;
2064 if (insn == bb->head)
2068 free_propagate_block_info (pbi);
2073 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2074 (SET expressions whose destinations are registers dead after the insn).
2075 NEEDED is the regset that says which regs are alive after the insn.
2077 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
2079 If X is the entire body of an insn, NOTES contains the reg notes
2080 pertaining to the insn. */
2083 insn_dead_p (pbi, x, call_ok, notes)
2084 struct propagate_block_info *pbi;
2087 rtx notes ATTRIBUTE_UNUSED;
2089 enum rtx_code code = GET_CODE (x);
2092 /* As flow is invoked after combine, we must take existing AUTO_INC
2093 expressions into account. */
2094 for (; notes; notes = XEXP (notes, 1))
2096 if (REG_NOTE_KIND (notes) == REG_INC)
2098 int regno = REGNO (XEXP (notes, 0));
2100 /* Don't delete insns to set global regs. */
2101 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2102 || REGNO_REG_SET_P (pbi->reg_live, regno))
2108 /* If setting something that's a reg or part of one,
2109 see if that register's altered value will be live. */
2113 rtx r = SET_DEST (x);
2116 if (GET_CODE (r) == CC0)
2117 return ! pbi->cc0_live;
2120 /* A SET that is a subroutine call cannot be dead. */
2121 if (GET_CODE (SET_SRC (x)) == CALL)
2127 /* Don't eliminate loads from volatile memory or volatile asms. */
2128 else if (volatile_refs_p (SET_SRC (x)))
2131 if (GET_CODE (r) == MEM)
2135 if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode)
2138 canon_r = canon_rtx (r);
2140 /* Walk the set of memory locations we are currently tracking
2141 and see if one is an identical match to this memory location.
2142 If so, this memory write is dead (remember, we're walking
2143 backwards from the end of the block to the start). Since
2144 rtx_equal_p does not check the alias set or flags, we also
2145 must have the potential for them to conflict (anti_dependence). */
2146 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
2147 if (anti_dependence (r, XEXP (temp, 0)))
2149 rtx mem = XEXP (temp, 0);
2151 if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0))
2152 && (GET_MODE_SIZE (GET_MODE (canon_r))
2153 <= GET_MODE_SIZE (GET_MODE (mem))))
2157 /* Check if memory reference matches an auto increment. Only
2158 post increment/decrement or modify are valid. */
2159 if (GET_MODE (mem) == GET_MODE (r)
2160 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
2161 || GET_CODE (XEXP (mem, 0)) == POST_INC
2162 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
2163 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
2164 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
2171 while (GET_CODE (r) == SUBREG
2172 || GET_CODE (r) == STRICT_LOW_PART
2173 || GET_CODE (r) == ZERO_EXTRACT)
2176 if (GET_CODE (r) == REG)
2178 int regno = REGNO (r);
2181 if (REGNO_REG_SET_P (pbi->reg_live, regno))
2184 /* If this is a hard register, verify that subsequent
2185 words are not needed. */
2186 if (regno < FIRST_PSEUDO_REGISTER)
2188 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
2191 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
2195 /* Don't delete insns to set global regs. */
2196 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2199 /* Make sure insns to set the stack pointer aren't deleted. */
2200 if (regno == STACK_POINTER_REGNUM)
2203 /* ??? These bits might be redundant with the force live bits
2204 in calculate_global_regs_live. We would delete from
2205 sequential sets; whether this actually affects real code
2206 for anything but the stack pointer I don't know. */
2207 /* Make sure insns to set the frame pointer aren't deleted. */
2208 if (regno == FRAME_POINTER_REGNUM
2209 && (! reload_completed || frame_pointer_needed))
2211 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2212 if (regno == HARD_FRAME_POINTER_REGNUM
2213 && (! reload_completed || frame_pointer_needed))
2217 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2218 /* Make sure insns to set arg pointer are never deleted
2219 (if the arg pointer isn't fixed, there will be a USE
2220 for it, so we can treat it normally). */
2221 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2225 /* Otherwise, the set is dead. */
2231 /* If performing several activities, insn is dead if each activity
2232 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2233 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2235 else if (code == PARALLEL)
2237 int i = XVECLEN (x, 0);
2239 for (i--; i >= 0; i--)
2240 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
2241 && GET_CODE (XVECEXP (x, 0, i)) != USE
2242 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
2248 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2249 is not necessarily true for hard registers. */
2250 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
2251 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
2252 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
2255 /* We do not check other CLOBBER or USE here. An insn consisting of just
2256 a CLOBBER or just a USE should not be deleted. */
2260 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2261 return 1 if the entire library call is dead.
2262 This is true if INSN copies a register (hard or pseudo)
2263 and if the hard return reg of the call insn is dead.
2264 (The caller should have tested the destination of the SET inside
2265 INSN already for death.)
2267 If this insn doesn't just copy a register, then we don't
2268 have an ordinary libcall. In that case, cse could not have
2269 managed to substitute the source for the dest later on,
2270 so we can assume the libcall is dead.
2272 PBI is the block info giving pseudoregs live before this insn.
2273 NOTE is the REG_RETVAL note of the insn. */
2276 libcall_dead_p (pbi, note, insn)
2277 struct propagate_block_info *pbi;
2281 rtx x = single_set (insn);
2285 rtx r = SET_SRC (x);
2287 if (GET_CODE (r) == REG)
2289 rtx call = XEXP (note, 0);
2293 /* Find the call insn. */
2294 while (call != insn && GET_CODE (call) != CALL_INSN)
2295 call = NEXT_INSN (call);
2297 /* If there is none, do nothing special,
2298 since ordinary death handling can understand these insns. */
2302 /* See if the hard reg holding the value is dead.
2303 If this is a PARALLEL, find the call within it. */
2304 call_pat = PATTERN (call);
2305 if (GET_CODE (call_pat) == PARALLEL)
2307 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
2308 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
2309 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
2312 /* This may be a library call that is returning a value
2313 via invisible pointer. Do nothing special, since
2314 ordinary death handling can understand these insns. */
2318 call_pat = XVECEXP (call_pat, 0, i);
2321 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
2327 /* Return 1 if register REGNO was used before it was set, i.e. if it is
2328 live at function entry. Don't count global register variables, variables
2329 in registers that can be used for function arg passing, or variables in
2330 fixed hard registers. */
2333 regno_uninitialized (regno)
2336 if (n_basic_blocks == 0
2337 || (regno < FIRST_PSEUDO_REGISTER
2338 && (global_regs[regno]
2339 || fixed_regs[regno]
2340 || FUNCTION_ARG_REGNO_P (regno))))
2343 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
2346 /* 1 if register REGNO was alive at a place where `setjmp' was called
2347 and was set more than once or is an argument.
2348 Such regs may be clobbered by `longjmp'. */
2351 regno_clobbered_at_setjmp (regno)
2354 if (n_basic_blocks == 0)
2357 return ((REG_N_SETS (regno) > 1
2358 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
2359 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
2362 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2363 maximal list size; look for overlaps in mode and select the largest. */
2365 add_to_mem_set_list (pbi, mem)
2366 struct propagate_block_info *pbi;
2371 /* We don't know how large a BLKmode store is, so we must not
2372 take them into consideration. */
2373 if (GET_MODE (mem) == BLKmode)
2376 for (i = pbi->mem_set_list; i ; i = XEXP (i, 1))
2378 rtx e = XEXP (i, 0);
2379 if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0)))
2381 if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e)))
2384 /* If we must store a copy of the mem, we can just modify
2385 the mode of the stored copy. */
2386 if (pbi->flags & PROP_AUTOINC)
2387 PUT_MODE (e, GET_MODE (mem));
2396 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN)
2399 /* Store a copy of mem, otherwise the address may be
2400 scrogged by find_auto_inc. */
2401 if (pbi->flags & PROP_AUTOINC)
2402 mem = shallow_copy_rtx (mem);
2404 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
2405 pbi->mem_set_list_len++;
2409 /* INSN references memory, possibly using autoincrement addressing modes.
2410 Find any entries on the mem_set_list that need to be invalidated due
2411 to an address change. */
2414 invalidate_mems_from_autoinc (pbi, insn)
2415 struct propagate_block_info *pbi;
2418 rtx note = REG_NOTES (insn);
2419 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
2420 if (REG_NOTE_KIND (note) == REG_INC)
2421 invalidate_mems_from_set (pbi, XEXP (note, 0));
2424 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2427 invalidate_mems_from_set (pbi, exp)
2428 struct propagate_block_info *pbi;
2431 rtx temp = pbi->mem_set_list;
2432 rtx prev = NULL_RTX;
2437 next = XEXP (temp, 1);
2438 if (reg_overlap_mentioned_p (exp, XEXP (temp, 0)))
2440 /* Splice this entry out of the list. */
2442 XEXP (prev, 1) = next;
2444 pbi->mem_set_list = next;
2445 free_EXPR_LIST_node (temp);
2446 pbi->mem_set_list_len--;
2454 /* Process the registers that are set within X. Their bits are set to
2455 1 in the regset DEAD, because they are dead prior to this insn.
2457 If INSN is nonzero, it is the insn being processed.
2459 FLAGS is the set of operations to perform. */
2462 mark_set_regs (pbi, x, insn)
2463 struct propagate_block_info *pbi;
2466 rtx cond = NULL_RTX;
2471 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2473 if (REG_NOTE_KIND (link) == REG_INC)
2474 mark_set_1 (pbi, SET, XEXP (link, 0),
2475 (GET_CODE (x) == COND_EXEC
2476 ? COND_EXEC_TEST (x) : NULL_RTX),
2480 switch (code = GET_CODE (x))
2484 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
2488 cond = COND_EXEC_TEST (x);
2489 x = COND_EXEC_CODE (x);
2496 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2498 rtx sub = XVECEXP (x, 0, i);
2499 switch (code = GET_CODE (sub))
2502 if (cond != NULL_RTX)
2505 cond = COND_EXEC_TEST (sub);
2506 sub = COND_EXEC_CODE (sub);
2507 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
2513 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
2528 /* Process a single set, which appears in INSN. REG (which may not
2529 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2530 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2531 If the set is conditional (because it appear in a COND_EXEC), COND
2532 will be the condition. */
2535 mark_set_1 (pbi, code, reg, cond, insn, flags)
2536 struct propagate_block_info *pbi;
2538 rtx reg, cond, insn;
2541 int regno_first = -1, regno_last = -1;
2542 unsigned long not_dead = 0;
2545 /* Modifying just one hardware register of a multi-reg value or just a
2546 byte field of a register does not mean the value from before this insn
2547 is now dead. Of course, if it was dead after it's unused now. */
2549 switch (GET_CODE (reg))
2552 /* Some targets place small structures in registers for return values of
2553 functions. We have to detect this case specially here to get correct
2554 flow information. */
2555 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
2556 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
2557 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
2563 case STRICT_LOW_PART:
2564 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2566 reg = XEXP (reg, 0);
2567 while (GET_CODE (reg) == SUBREG
2568 || GET_CODE (reg) == ZERO_EXTRACT
2569 || GET_CODE (reg) == SIGN_EXTRACT
2570 || GET_CODE (reg) == STRICT_LOW_PART);
2571 if (GET_CODE (reg) == MEM)
2573 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
2577 regno_last = regno_first = REGNO (reg);
2578 if (regno_first < FIRST_PSEUDO_REGISTER)
2579 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
2583 if (GET_CODE (SUBREG_REG (reg)) == REG)
2585 enum machine_mode outer_mode = GET_MODE (reg);
2586 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
2588 /* Identify the range of registers affected. This is moderately
2589 tricky for hard registers. See alter_subreg. */
2591 regno_last = regno_first = REGNO (SUBREG_REG (reg));
2592 if (regno_first < FIRST_PSEUDO_REGISTER)
2594 regno_first += subreg_regno_offset (regno_first, inner_mode,
2597 regno_last = (regno_first
2598 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
2600 /* Since we've just adjusted the register number ranges, make
2601 sure REG matches. Otherwise some_was_live will be clear
2602 when it shouldn't have been, and we'll create incorrect
2603 REG_UNUSED notes. */
2604 reg = gen_rtx_REG (outer_mode, regno_first);
2608 /* If the number of words in the subreg is less than the number
2609 of words in the full register, we have a well-defined partial
2610 set. Otherwise the high bits are undefined.
2612 This is only really applicable to pseudos, since we just took
2613 care of multi-word hard registers. */
2614 if (((GET_MODE_SIZE (outer_mode)
2615 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
2616 < ((GET_MODE_SIZE (inner_mode)
2617 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
2618 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
2621 reg = SUBREG_REG (reg);
2625 reg = SUBREG_REG (reg);
2632 /* If this set is a MEM, then it kills any aliased writes.
2633 If this set is a REG, then it kills any MEMs which use the reg. */
2634 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2636 if (GET_CODE (reg) == REG)
2637 invalidate_mems_from_set (pbi, reg);
2639 /* If the memory reference had embedded side effects (autoincrement
2640 address modes. Then we may need to kill some entries on the
2642 if (insn && GET_CODE (reg) == MEM)
2643 invalidate_mems_from_autoinc (pbi, insn);
2645 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
2646 /* ??? With more effort we could track conditional memory life. */
2648 /* There are no REG_INC notes for SP, so we can't assume we'll see
2649 everything that invalidates it. To be safe, don't eliminate any
2650 stores though SP; none of them should be redundant anyway. */
2651 && ! reg_mentioned_p (stack_pointer_rtx, reg))
2652 add_to_mem_set_list (pbi, canon_rtx (reg));
2655 if (GET_CODE (reg) == REG
2656 && ! (regno_first == FRAME_POINTER_REGNUM
2657 && (! reload_completed || frame_pointer_needed))
2658 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2659 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
2660 && (! reload_completed || frame_pointer_needed))
2662 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2663 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
2667 int some_was_live = 0, some_was_dead = 0;
2669 for (i = regno_first; i <= regno_last; ++i)
2671 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
2674 /* Order of the set operation matters here since both
2675 sets may be the same. */
2676 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
2677 if (cond != NULL_RTX
2678 && ! REGNO_REG_SET_P (pbi->local_set, i))
2679 SET_REGNO_REG_SET (pbi->cond_local_set, i);
2681 SET_REGNO_REG_SET (pbi->local_set, i);
2683 if (code != CLOBBER)
2684 SET_REGNO_REG_SET (pbi->new_set, i);
2686 some_was_live |= needed_regno;
2687 some_was_dead |= ! needed_regno;
2690 #ifdef HAVE_conditional_execution
2691 /* Consider conditional death in deciding that the register needs
2693 if (some_was_live && ! not_dead
2694 /* The stack pointer is never dead. Well, not strictly true,
2695 but it's very difficult to tell from here. Hopefully
2696 combine_stack_adjustments will fix up the most egregious
2698 && regno_first != STACK_POINTER_REGNUM)
2700 for (i = regno_first; i <= regno_last; ++i)
2701 if (! mark_regno_cond_dead (pbi, i, cond))
2702 not_dead |= ((unsigned long) 1) << (i - regno_first);
2706 /* Additional data to record if this is the final pass. */
2707 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
2708 | PROP_DEATH_NOTES | PROP_AUTOINC))
2711 int blocknum = pbi->bb->index;
2714 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2716 y = pbi->reg_next_use[regno_first];
2718 /* The next use is no longer next, since a store intervenes. */
2719 for (i = regno_first; i <= regno_last; ++i)
2720 pbi->reg_next_use[i] = 0;
2723 if (flags & PROP_REG_INFO)
2725 for (i = regno_first; i <= regno_last; ++i)
2727 /* Count (weighted) references, stores, etc. This counts a
2728 register twice if it is modified, but that is correct. */
2729 REG_N_SETS (i) += 1;
2730 REG_N_REFS (i) += 1;
2731 REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb);
2733 /* The insns where a reg is live are normally counted
2734 elsewhere, but we want the count to include the insn
2735 where the reg is set, and the normal counting mechanism
2736 would not count it. */
2737 REG_LIVE_LENGTH (i) += 1;
2740 /* If this is a hard reg, record this function uses the reg. */
2741 if (regno_first < FIRST_PSEUDO_REGISTER)
2743 for (i = regno_first; i <= regno_last; i++)
2744 regs_ever_live[i] = 1;
2748 /* Keep track of which basic blocks each reg appears in. */
2749 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
2750 REG_BASIC_BLOCK (regno_first) = blocknum;
2751 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
2752 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
2756 if (! some_was_dead)
2758 if (flags & PROP_LOG_LINKS)
2760 /* Make a logical link from the next following insn
2761 that uses this register, back to this insn.
2762 The following insns have already been processed.
2764 We don't build a LOG_LINK for hard registers containing
2765 in ASM_OPERANDs. If these registers get replaced,
2766 we might wind up changing the semantics of the insn,
2767 even if reload can make what appear to be valid
2768 assignments later. */
2769 if (y && (BLOCK_NUM (y) == blocknum)
2770 && (regno_first >= FIRST_PSEUDO_REGISTER
2771 || asm_noperands (PATTERN (y)) < 0))
2772 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
2777 else if (! some_was_live)
2779 if (flags & PROP_REG_INFO)
2780 REG_N_DEATHS (regno_first) += 1;
2782 if (flags & PROP_DEATH_NOTES)
2784 /* Note that dead stores have already been deleted
2785 when possible. If we get here, we have found a
2786 dead store that cannot be eliminated (because the
2787 same insn does something useful). Indicate this
2788 by marking the reg being set as dying here. */
2790 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2795 if (flags & PROP_DEATH_NOTES)
2797 /* This is a case where we have a multi-word hard register
2798 and some, but not all, of the words of the register are
2799 needed in subsequent insns. Write REG_UNUSED notes
2800 for those parts that were not needed. This case should
2803 for (i = regno_first; i <= regno_last; ++i)
2804 if (! REGNO_REG_SET_P (pbi->reg_live, i))
2806 = alloc_EXPR_LIST (REG_UNUSED,
2807 gen_rtx_REG (reg_raw_mode[i], i),
2813 /* Mark the register as being dead. */
2815 /* The stack pointer is never dead. Well, not strictly true,
2816 but it's very difficult to tell from here. Hopefully
2817 combine_stack_adjustments will fix up the most egregious
2819 && regno_first != STACK_POINTER_REGNUM)
2821 for (i = regno_first; i <= regno_last; ++i)
2822 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
2823 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
2826 else if (GET_CODE (reg) == REG)
2828 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2829 pbi->reg_next_use[regno_first] = 0;
2832 /* If this is the last pass and this is a SCRATCH, show it will be dying
2833 here and count it. */
2834 else if (GET_CODE (reg) == SCRATCH)
2836 if (flags & PROP_DEATH_NOTES)
2838 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2842 #ifdef HAVE_conditional_execution
2843 /* Mark REGNO conditionally dead.
2844 Return true if the register is now unconditionally dead. */
2847 mark_regno_cond_dead (pbi, regno, cond)
2848 struct propagate_block_info *pbi;
2852 /* If this is a store to a predicate register, the value of the
2853 predicate is changing, we don't know that the predicate as seen
2854 before is the same as that seen after. Flush all dependent
2855 conditions from reg_cond_dead. This will make all such
2856 conditionally live registers unconditionally live. */
2857 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
2858 flush_reg_cond_reg (pbi, regno);
2860 /* If this is an unconditional store, remove any conditional
2861 life that may have existed. */
2862 if (cond == NULL_RTX)
2863 splay_tree_remove (pbi->reg_cond_dead, regno);
2866 splay_tree_node node;
2867 struct reg_cond_life_info *rcli;
2870 /* Otherwise this is a conditional set. Record that fact.
2871 It may have been conditionally used, or there may be a
2872 subsequent set with a complimentary condition. */
2874 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
2877 /* The register was unconditionally live previously.
2878 Record the current condition as the condition under
2879 which it is dead. */
2880 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
2881 rcli->condition = cond;
2882 rcli->stores = cond;
2883 rcli->orig_condition = const0_rtx;
2884 splay_tree_insert (pbi->reg_cond_dead, regno,
2885 (splay_tree_value) rcli);
2887 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2889 /* Not unconditionally dead. */
2894 /* The register was conditionally live previously.
2895 Add the new condition to the old. */
2896 rcli = (struct reg_cond_life_info *) node->value;
2897 ncond = rcli->condition;
2898 ncond = ior_reg_cond (ncond, cond, 1);
2899 if (rcli->stores == const0_rtx)
2900 rcli->stores = cond;
2901 else if (rcli->stores != const1_rtx)
2902 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
2904 /* If the register is now unconditionally dead, remove the entry
2905 in the splay_tree. A register is unconditionally dead if the
2906 dead condition ncond is true. A register is also unconditionally
2907 dead if the sum of all conditional stores is an unconditional
2908 store (stores is true), and the dead condition is identically the
2909 same as the original dead condition initialized at the end of
2910 the block. This is a pointer compare, not an rtx_equal_p
2912 if (ncond == const1_rtx
2913 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
2914 splay_tree_remove (pbi->reg_cond_dead, regno);
2917 rcli->condition = ncond;
2919 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2921 /* Not unconditionally dead. */
2930 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2933 free_reg_cond_life_info (value)
2934 splay_tree_value value;
2936 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
2940 /* Helper function for flush_reg_cond_reg. */
2943 flush_reg_cond_reg_1 (node, data)
2944 splay_tree_node node;
2947 struct reg_cond_life_info *rcli;
2948 int *xdata = (int *) data;
2949 unsigned int regno = xdata[0];
2951 /* Don't need to search if last flushed value was farther on in
2952 the in-order traversal. */
2953 if (xdata[1] >= (int) node->key)
2956 /* Splice out portions of the expression that refer to regno. */
2957 rcli = (struct reg_cond_life_info *) node->value;
2958 rcli->condition = elim_reg_cond (rcli->condition, regno);
2959 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
2960 rcli->stores = elim_reg_cond (rcli->stores, regno);
2962 /* If the entire condition is now false, signal the node to be removed. */
2963 if (rcli->condition == const0_rtx)
2965 xdata[1] = node->key;
2968 else if (rcli->condition == const1_rtx)
2974 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2977 flush_reg_cond_reg (pbi, regno)
2978 struct propagate_block_info *pbi;
2985 while (splay_tree_foreach (pbi->reg_cond_dead,
2986 flush_reg_cond_reg_1, pair) == -1)
2987 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
2989 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
2992 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2993 For ior/and, the ADD flag determines whether we want to add the new
2994 condition X to the old one unconditionally. If it is zero, we will
2995 only return a new expression if X allows us to simplify part of
2996 OLD, otherwise we return NULL to the caller.
2997 If ADD is nonzero, we will return a new condition in all cases. The
2998 toplevel caller of one of these functions should always pass 1 for
3002 ior_reg_cond (old, x, add)
3008 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
3010 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
3011 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
3012 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3014 if (GET_CODE (x) == GET_CODE (old)
3015 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3019 return gen_rtx_IOR (0, old, x);
3022 switch (GET_CODE (old))
3025 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3026 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3027 if (op0 != NULL || op1 != NULL)
3029 if (op0 == const0_rtx)
3030 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3031 if (op1 == const0_rtx)
3032 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3033 if (op0 == const1_rtx || op1 == const1_rtx)
3036 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3037 else if (rtx_equal_p (x, op0))
3038 /* (x | A) | x ~ (x | A). */
3041 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3042 else if (rtx_equal_p (x, op1))
3043 /* (A | x) | x ~ (A | x). */
3045 return gen_rtx_IOR (0, op0, op1);
3049 return gen_rtx_IOR (0, old, x);
3052 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3053 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3054 if (op0 != NULL || op1 != NULL)
3056 if (op0 == const1_rtx)
3057 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3058 if (op1 == const1_rtx)
3059 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3060 if (op0 == const0_rtx || op1 == const0_rtx)
3063 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3064 else if (rtx_equal_p (x, op0))
3065 /* (x & A) | x ~ x. */
3068 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3069 else if (rtx_equal_p (x, op1))
3070 /* (A & x) | x ~ x. */
3072 return gen_rtx_AND (0, op0, op1);
3076 return gen_rtx_IOR (0, old, x);
3079 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3081 return not_reg_cond (op0);
3084 return gen_rtx_IOR (0, old, x);
3095 enum rtx_code x_code;
3097 if (x == const0_rtx)
3099 else if (x == const1_rtx)
3101 x_code = GET_CODE (x);
3104 if (GET_RTX_CLASS (x_code) == '<'
3105 && GET_CODE (XEXP (x, 0)) == REG)
3107 if (XEXP (x, 1) != const0_rtx)
3110 return gen_rtx_fmt_ee (reverse_condition (x_code),
3111 VOIDmode, XEXP (x, 0), const0_rtx);
3113 return gen_rtx_NOT (0, x);
3117 and_reg_cond (old, x, add)
3123 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
3125 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
3126 && GET_CODE (x) == reverse_condition (GET_CODE (old))
3127 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3129 if (GET_CODE (x) == GET_CODE (old)
3130 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3134 return gen_rtx_AND (0, old, x);
3137 switch (GET_CODE (old))
3140 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3141 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3142 if (op0 != NULL || op1 != NULL)
3144 if (op0 == const0_rtx)
3145 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3146 if (op1 == const0_rtx)
3147 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3148 if (op0 == const1_rtx || op1 == const1_rtx)
3151 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3152 else if (rtx_equal_p (x, op0))
3153 /* (x | A) & x ~ x. */
3156 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3157 else if (rtx_equal_p (x, op1))
3158 /* (A | x) & x ~ x. */
3160 return gen_rtx_IOR (0, op0, op1);
3164 return gen_rtx_AND (0, old, x);
3167 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3168 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3169 if (op0 != NULL || op1 != NULL)
3171 if (op0 == const1_rtx)
3172 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3173 if (op1 == const1_rtx)
3174 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3175 if (op0 == const0_rtx || op1 == const0_rtx)
3178 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3179 else if (rtx_equal_p (x, op0))
3180 /* (x & A) & x ~ (x & A). */
3183 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3184 else if (rtx_equal_p (x, op1))
3185 /* (A & x) & x ~ (A & x). */
3187 return gen_rtx_AND (0, op0, op1);
3191 return gen_rtx_AND (0, old, x);
3194 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3196 return not_reg_cond (op0);
3199 return gen_rtx_AND (0, old, x);
3206 /* Given a condition X, remove references to reg REGNO and return the
3207 new condition. The removal will be done so that all conditions
3208 involving REGNO are considered to evaluate to false. This function
3209 is used when the value of REGNO changes. */
3212 elim_reg_cond (x, regno)
3218 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
3220 if (REGNO (XEXP (x, 0)) == regno)
3225 switch (GET_CODE (x))
3228 op0 = elim_reg_cond (XEXP (x, 0), regno);
3229 op1 = elim_reg_cond (XEXP (x, 1), regno);
3230 if (op0 == const0_rtx || op1 == const0_rtx)
3232 if (op0 == const1_rtx)
3234 if (op1 == const1_rtx)
3236 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3238 return gen_rtx_AND (0, op0, op1);
3241 op0 = elim_reg_cond (XEXP (x, 0), regno);
3242 op1 = elim_reg_cond (XEXP (x, 1), regno);
3243 if (op0 == const1_rtx || op1 == const1_rtx)
3245 if (op0 == const0_rtx)
3247 if (op1 == const0_rtx)
3249 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3251 return gen_rtx_IOR (0, op0, op1);
3254 op0 = elim_reg_cond (XEXP (x, 0), regno);
3255 if (op0 == const0_rtx)
3257 if (op0 == const1_rtx)
3259 if (op0 != XEXP (x, 0))
3260 return not_reg_cond (op0);
3267 #endif /* HAVE_conditional_execution */
3271 /* Try to substitute the auto-inc expression INC as the address inside
3272 MEM which occurs in INSN. Currently, the address of MEM is an expression
3273 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3274 that has a single set whose source is a PLUS of INCR_REG and something
3278 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
3279 struct propagate_block_info *pbi;
3280 rtx inc, insn, mem, incr, incr_reg;
3282 int regno = REGNO (incr_reg);
3283 rtx set = single_set (incr);
3284 rtx q = SET_DEST (set);
3285 rtx y = SET_SRC (set);
3286 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
3288 /* Make sure this reg appears only once in this insn. */
3289 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
3292 if (dead_or_set_p (incr, incr_reg)
3293 /* Mustn't autoinc an eliminable register. */
3294 && (regno >= FIRST_PSEUDO_REGISTER
3295 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
3297 /* This is the simple case. Try to make the auto-inc. If
3298 we can't, we are done. Otherwise, we will do any
3299 needed updates below. */
3300 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
3303 else if (GET_CODE (q) == REG
3304 /* PREV_INSN used here to check the semi-open interval
3306 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
3307 /* We must also check for sets of q as q may be
3308 a call clobbered hard register and there may
3309 be a call between PREV_INSN (insn) and incr. */
3310 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
3312 /* We have *p followed sometime later by q = p+size.
3313 Both p and q must be live afterward,
3314 and q is not used between INSN and its assignment.
3315 Change it to q = p, ...*q..., q = q+size.
3316 Then fall into the usual case. */
3320 emit_move_insn (q, incr_reg);
3321 insns = get_insns ();
3324 /* If we can't make the auto-inc, or can't make the
3325 replacement into Y, exit. There's no point in making
3326 the change below if we can't do the auto-inc and doing
3327 so is not correct in the pre-inc case. */
3330 validate_change (insn, &XEXP (mem, 0), inc, 1);
3331 validate_change (incr, &XEXP (y, opnum), q, 1);
3332 if (! apply_change_group ())
3335 /* We now know we'll be doing this change, so emit the
3336 new insn(s) and do the updates. */
3337 emit_insns_before (insns, insn);
3339 if (pbi->bb->head == insn)
3340 pbi->bb->head = insns;
3342 /* INCR will become a NOTE and INSN won't contain a
3343 use of INCR_REG. If a use of INCR_REG was just placed in
3344 the insn before INSN, make that the next use.
3345 Otherwise, invalidate it. */
3346 if (GET_CODE (PREV_INSN (insn)) == INSN
3347 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
3348 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
3349 pbi->reg_next_use[regno] = PREV_INSN (insn);
3351 pbi->reg_next_use[regno] = 0;
3356 /* REGNO is now used in INCR which is below INSN, but
3357 it previously wasn't live here. If we don't mark
3358 it as live, we'll put a REG_DEAD note for it
3359 on this insn, which is incorrect. */
3360 SET_REGNO_REG_SET (pbi->reg_live, regno);
3362 /* If there are any calls between INSN and INCR, show
3363 that REGNO now crosses them. */
3364 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
3365 if (GET_CODE (temp) == CALL_INSN)
3366 REG_N_CALLS_CROSSED (regno)++;
3368 /* Invalidate alias info for Q since we just changed its value. */
3369 clear_reg_alias_info (q);
3374 /* If we haven't returned, it means we were able to make the
3375 auto-inc, so update the status. First, record that this insn
3376 has an implicit side effect. */
3378 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
3380 /* Modify the old increment-insn to simply copy
3381 the already-incremented value of our register. */
3382 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
3385 /* If that makes it a no-op (copying the register into itself) delete
3386 it so it won't appear to be a "use" and a "set" of this
3388 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
3390 /* If the original source was dead, it's dead now. */
3393 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
3395 remove_note (incr, note);
3396 if (XEXP (note, 0) != incr_reg)
3397 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
3400 PUT_CODE (incr, NOTE);
3401 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
3402 NOTE_SOURCE_FILE (incr) = 0;
3405 if (regno >= FIRST_PSEUDO_REGISTER)
3407 /* Count an extra reference to the reg. When a reg is
3408 incremented, spilling it is worse, so we want to make
3409 that less likely. */
3410 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3412 /* Count the increment as a setting of the register,
3413 even though it isn't a SET in rtl. */
3414 REG_N_SETS (regno)++;
3418 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3422 find_auto_inc (pbi, x, insn)
3423 struct propagate_block_info *pbi;
3427 rtx addr = XEXP (x, 0);
3428 HOST_WIDE_INT offset = 0;
3429 rtx set, y, incr, inc_val;
3431 int size = GET_MODE_SIZE (GET_MODE (x));
3433 if (GET_CODE (insn) == JUMP_INSN)
3436 /* Here we detect use of an index register which might be good for
3437 postincrement, postdecrement, preincrement, or predecrement. */
3439 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
3440 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
3442 if (GET_CODE (addr) != REG)
3445 regno = REGNO (addr);
3447 /* Is the next use an increment that might make auto-increment? */
3448 incr = pbi->reg_next_use[regno];
3449 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
3451 set = single_set (incr);
3452 if (set == 0 || GET_CODE (set) != SET)
3456 if (GET_CODE (y) != PLUS)
3459 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
3460 inc_val = XEXP (y, 1);
3461 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
3462 inc_val = XEXP (y, 0);
3466 if (GET_CODE (inc_val) == CONST_INT)
3468 if (HAVE_POST_INCREMENT
3469 && (INTVAL (inc_val) == size && offset == 0))
3470 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
3472 else if (HAVE_POST_DECREMENT
3473 && (INTVAL (inc_val) == -size && offset == 0))
3474 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
3476 else if (HAVE_PRE_INCREMENT
3477 && (INTVAL (inc_val) == size && offset == size))
3478 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
3480 else if (HAVE_PRE_DECREMENT
3481 && (INTVAL (inc_val) == -size && offset == -size))
3482 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
3484 else if (HAVE_POST_MODIFY_DISP && offset == 0)
3485 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3486 gen_rtx_PLUS (Pmode,
3489 insn, x, incr, addr);
3491 else if (GET_CODE (inc_val) == REG
3492 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
3496 if (HAVE_POST_MODIFY_REG && offset == 0)
3497 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3498 gen_rtx_PLUS (Pmode,
3501 insn, x, incr, addr);
3505 #endif /* AUTO_INC_DEC */
3508 mark_used_reg (pbi, reg, cond, insn)
3509 struct propagate_block_info *pbi;
3511 rtx cond ATTRIBUTE_UNUSED;
3514 unsigned int regno_first, regno_last, i;
3515 int some_was_live, some_was_dead, some_not_set;
3517 regno_last = regno_first = REGNO (reg);
3518 if (regno_first < FIRST_PSEUDO_REGISTER)
3519 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
3521 /* Find out if any of this register is live after this instruction. */
3522 some_was_live = some_was_dead = 0;
3523 for (i = regno_first; i <= regno_last; ++i)
3525 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
3526 some_was_live |= needed_regno;
3527 some_was_dead |= ! needed_regno;
3530 /* Find out if any of the register was set this insn. */
3532 for (i = regno_first; i <= regno_last; ++i)
3533 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
3535 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3537 /* Record where each reg is used, so when the reg is set we know
3538 the next insn that uses it. */
3539 pbi->reg_next_use[regno_first] = insn;
3542 if (pbi->flags & PROP_REG_INFO)
3544 if (regno_first < FIRST_PSEUDO_REGISTER)
3546 /* If this is a register we are going to try to eliminate,
3547 don't mark it live here. If we are successful in
3548 eliminating it, it need not be live unless it is used for
3549 pseudos, in which case it will have been set live when it
3550 was allocated to the pseudos. If the register will not
3551 be eliminated, reload will set it live at that point.
3553 Otherwise, record that this function uses this register. */
3554 /* ??? The PPC backend tries to "eliminate" on the pic
3555 register to itself. This should be fixed. In the mean
3556 time, hack around it. */
3558 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
3559 && (regno_first == FRAME_POINTER_REGNUM
3560 || regno_first == ARG_POINTER_REGNUM)))
3561 for (i = regno_first; i <= regno_last; ++i)
3562 regs_ever_live[i] = 1;
3566 /* Keep track of which basic block each reg appears in. */
3568 int blocknum = pbi->bb->index;
3569 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
3570 REG_BASIC_BLOCK (regno_first) = blocknum;
3571 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
3572 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
3574 /* Count (weighted) number of uses of each reg. */
3575 REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb);
3576 REG_N_REFS (regno_first)++;
3580 /* Record and count the insns in which a reg dies. If it is used in
3581 this insn and was dead below the insn then it dies in this insn.
3582 If it was set in this insn, we do not make a REG_DEAD note;
3583 likewise if we already made such a note. */
3584 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
3588 /* Check for the case where the register dying partially
3589 overlaps the register set by this insn. */
3590 if (regno_first != regno_last)
3591 for (i = regno_first; i <= regno_last; ++i)
3592 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
3594 /* If none of the words in X is needed, make a REG_DEAD note.
3595 Otherwise, we must make partial REG_DEAD notes. */
3596 if (! some_was_live)
3598 if ((pbi->flags & PROP_DEATH_NOTES)
3599 && ! find_regno_note (insn, REG_DEAD, regno_first))
3601 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
3603 if (pbi->flags & PROP_REG_INFO)
3604 REG_N_DEATHS (regno_first)++;
3608 /* Don't make a REG_DEAD note for a part of a register
3609 that is set in the insn. */
3610 for (i = regno_first; i <= regno_last; ++i)
3611 if (! REGNO_REG_SET_P (pbi->reg_live, i)
3612 && ! dead_or_set_regno_p (insn, i))
3614 = alloc_EXPR_LIST (REG_DEAD,
3615 gen_rtx_REG (reg_raw_mode[i], i),
3620 /* Mark the register as being live. */
3621 for (i = regno_first; i <= regno_last; ++i)
3623 #ifdef HAVE_conditional_execution
3624 int this_was_live = REGNO_REG_SET_P (pbi->reg_live, i);
3627 SET_REGNO_REG_SET (pbi->reg_live, i);
3629 #ifdef HAVE_conditional_execution
3630 /* If this is a conditional use, record that fact. If it is later
3631 conditionally set, we'll know to kill the register. */
3632 if (cond != NULL_RTX)
3634 splay_tree_node node;
3635 struct reg_cond_life_info *rcli;
3640 node = splay_tree_lookup (pbi->reg_cond_dead, i);
3643 /* The register was unconditionally live previously.
3644 No need to do anything. */
3648 /* The register was conditionally live previously.
3649 Subtract the new life cond from the old death cond. */
3650 rcli = (struct reg_cond_life_info *) node->value;
3651 ncond = rcli->condition;
3652 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
3654 /* If the register is now unconditionally live,
3655 remove the entry in the splay_tree. */
3656 if (ncond == const0_rtx)
3657 splay_tree_remove (pbi->reg_cond_dead, i);
3660 rcli->condition = ncond;
3661 SET_REGNO_REG_SET (pbi->reg_cond_reg,
3662 REGNO (XEXP (cond, 0)));
3668 /* The register was not previously live at all. Record
3669 the condition under which it is still dead. */
3670 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
3671 rcli->condition = not_reg_cond (cond);
3672 rcli->stores = const0_rtx;
3673 rcli->orig_condition = const0_rtx;
3674 splay_tree_insert (pbi->reg_cond_dead, i,
3675 (splay_tree_value) rcli);
3677 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
3680 else if (this_was_live)
3682 /* The register may have been conditionally live previously, but
3683 is now unconditionally live. Remove it from the conditionally
3684 dead list, so that a conditional set won't cause us to think
3686 splay_tree_remove (pbi->reg_cond_dead, i);
3692 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3693 This is done assuming the registers needed from X are those that
3694 have 1-bits in PBI->REG_LIVE.
3696 INSN is the containing instruction. If INSN is dead, this function
3700 mark_used_regs (pbi, x, cond, insn)
3701 struct propagate_block_info *pbi;
3706 int flags = pbi->flags;
3711 code = GET_CODE (x);
3732 /* If we are clobbering a MEM, mark any registers inside the address
3734 if (GET_CODE (XEXP (x, 0)) == MEM)
3735 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
3739 /* Don't bother watching stores to mems if this is not the
3740 final pass. We'll not be deleting dead stores this round. */
3741 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
3743 /* Invalidate the data for the last MEM stored, but only if MEM is
3744 something that can be stored into. */
3745 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3746 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3747 /* Needn't clear the memory set list. */
3751 rtx temp = pbi->mem_set_list;
3752 rtx prev = NULL_RTX;
3757 next = XEXP (temp, 1);
3758 if (anti_dependence (XEXP (temp, 0), x))
3760 /* Splice temp out of the list. */
3762 XEXP (prev, 1) = next;
3764 pbi->mem_set_list = next;
3765 free_EXPR_LIST_node (temp);
3766 pbi->mem_set_list_len--;
3774 /* If the memory reference had embedded side effects (autoincrement
3775 address modes. Then we may need to kill some entries on the
3778 invalidate_mems_from_autoinc (pbi, insn);
3782 if (flags & PROP_AUTOINC)
3783 find_auto_inc (pbi, x, insn);
3788 #ifdef CLASS_CANNOT_CHANGE_MODE
3789 if (GET_CODE (SUBREG_REG (x)) == REG
3790 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
3791 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
3792 GET_MODE (SUBREG_REG (x))))
3793 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
3796 /* While we're here, optimize this case. */
3798 if (GET_CODE (x) != REG)
3803 /* See a register other than being set => mark it as needed. */
3804 mark_used_reg (pbi, x, cond, insn);
3809 rtx testreg = SET_DEST (x);
3812 /* If storing into MEM, don't show it as being used. But do
3813 show the address as being used. */
3814 if (GET_CODE (testreg) == MEM)
3817 if (flags & PROP_AUTOINC)
3818 find_auto_inc (pbi, testreg, insn);
3820 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
3821 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3825 /* Storing in STRICT_LOW_PART is like storing in a reg
3826 in that this SET might be dead, so ignore it in TESTREG.
3827 but in some other ways it is like using the reg.
3829 Storing in a SUBREG or a bit field is like storing the entire
3830 register in that if the register's value is not used
3831 then this SET is not needed. */
3832 while (GET_CODE (testreg) == STRICT_LOW_PART
3833 || GET_CODE (testreg) == ZERO_EXTRACT
3834 || GET_CODE (testreg) == SIGN_EXTRACT
3835 || GET_CODE (testreg) == SUBREG)
3837 #ifdef CLASS_CANNOT_CHANGE_MODE
3838 if (GET_CODE (testreg) == SUBREG
3839 && GET_CODE (SUBREG_REG (testreg)) == REG
3840 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
3841 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
3842 GET_MODE (testreg)))
3843 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
3846 /* Modifying a single register in an alternate mode
3847 does not use any of the old value. But these other
3848 ways of storing in a register do use the old value. */
3849 if (GET_CODE (testreg) == SUBREG
3850 && !((REG_BYTES (SUBREG_REG (testreg))
3851 + UNITS_PER_WORD - 1) / UNITS_PER_WORD
3852 > (REG_BYTES (testreg)
3853 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
3858 testreg = XEXP (testreg, 0);
3861 /* If this is a store into a register or group of registers,
3862 recursively scan the value being stored. */
3864 if ((GET_CODE (testreg) == PARALLEL
3865 && GET_MODE (testreg) == BLKmode)
3866 || (GET_CODE (testreg) == REG
3867 && (regno = REGNO (testreg),
3868 ! (regno == FRAME_POINTER_REGNUM
3869 && (! reload_completed || frame_pointer_needed)))
3870 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3871 && ! (regno == HARD_FRAME_POINTER_REGNUM
3872 && (! reload_completed || frame_pointer_needed))
3874 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3875 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
3880 mark_used_regs (pbi, SET_DEST (x), cond, insn);
3881 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3888 case UNSPEC_VOLATILE:
3892 /* Traditional and volatile asm instructions must be considered to use
3893 and clobber all hard registers, all pseudo-registers and all of
3894 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3896 Consider for instance a volatile asm that changes the fpu rounding
3897 mode. An insn should not be moved across this even if it only uses
3898 pseudo-regs because it might give an incorrectly rounded result.
3900 ?!? Unfortunately, marking all hard registers as live causes massive
3901 problems for the register allocator and marking all pseudos as live
3902 creates mountains of uninitialized variable warnings.
3904 So for now, just clear the memory set list and mark any regs
3905 we can find in ASM_OPERANDS as used. */
3906 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
3908 free_EXPR_LIST_list (&pbi->mem_set_list);
3909 pbi->mem_set_list_len = 0;
3912 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3913 We can not just fall through here since then we would be confused
3914 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3915 traditional asms unlike their normal usage. */
3916 if (code == ASM_OPERANDS)
3920 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
3921 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
3927 if (cond != NULL_RTX)
3930 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
3932 cond = COND_EXEC_TEST (x);
3933 x = COND_EXEC_CODE (x);
3937 /* We _do_not_ want to scan operands of phi nodes. Operands of
3938 a phi function are evaluated only when control reaches this
3939 block along a particular edge. Therefore, regs that appear
3940 as arguments to phi should not be added to the global live at
3948 /* Recursively scan the operands of this expression. */
3951 const char * const fmt = GET_RTX_FORMAT (code);
3954 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3958 /* Tail recursive case: save a function call level. */
3964 mark_used_regs (pbi, XEXP (x, i), cond, insn);
3966 else if (fmt[i] == 'E')
3969 for (j = 0; j < XVECLEN (x, i); j++)
3970 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
3979 try_pre_increment_1 (pbi, insn)
3980 struct propagate_block_info *pbi;
3983 /* Find the next use of this reg. If in same basic block,
3984 make it do pre-increment or pre-decrement if appropriate. */
3985 rtx x = single_set (insn);
3986 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
3987 * INTVAL (XEXP (SET_SRC (x), 1)));
3988 int regno = REGNO (SET_DEST (x));
3989 rtx y = pbi->reg_next_use[regno];
3991 && SET_DEST (x) != stack_pointer_rtx
3992 && BLOCK_NUM (y) == BLOCK_NUM (insn)
3993 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3994 mode would be better. */
3995 && ! dead_or_set_p (y, SET_DEST (x))
3996 && try_pre_increment (y, SET_DEST (x), amount))
3998 /* We have found a suitable auto-increment and already changed
3999 insn Y to do it. So flush this increment instruction. */
4000 propagate_block_delete_insn (pbi->bb, insn);
4002 /* Count a reference to this reg for the increment insn we are
4003 deleting. When a reg is incremented, spilling it is worse,
4004 so we want to make that less likely. */
4005 if (regno >= FIRST_PSEUDO_REGISTER)
4007 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
4008 REG_N_SETS (regno)++;
4011 /* Flush any remembered memories depending on the value of
4012 the incremented register. */
4013 invalidate_mems_from_set (pbi, SET_DEST (x));
4020 /* Try to change INSN so that it does pre-increment or pre-decrement
4021 addressing on register REG in order to add AMOUNT to REG.
4022 AMOUNT is negative for pre-decrement.
4023 Returns 1 if the change could be made.
4024 This checks all about the validity of the result of modifying INSN. */
4027 try_pre_increment (insn, reg, amount)
4029 HOST_WIDE_INT amount;
4033 /* Nonzero if we can try to make a pre-increment or pre-decrement.
4034 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
4036 /* Nonzero if we can try to make a post-increment or post-decrement.
4037 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
4038 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
4039 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
4042 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
4045 /* From the sign of increment, see which possibilities are conceivable
4046 on this target machine. */
4047 if (HAVE_PRE_INCREMENT && amount > 0)
4049 if (HAVE_POST_INCREMENT && amount > 0)
4052 if (HAVE_PRE_DECREMENT && amount < 0)
4054 if (HAVE_POST_DECREMENT && amount < 0)
4057 if (! (pre_ok || post_ok))
4060 /* It is not safe to add a side effect to a jump insn
4061 because if the incremented register is spilled and must be reloaded
4062 there would be no way to store the incremented value back in memory. */
4064 if (GET_CODE (insn) == JUMP_INSN)
4069 use = find_use_as_address (PATTERN (insn), reg, 0);
4070 if (post_ok && (use == 0 || use == (rtx) (size_t) 1))
4072 use = find_use_as_address (PATTERN (insn), reg, -amount);
4076 if (use == 0 || use == (rtx) (size_t) 1)
4079 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
4082 /* See if this combination of instruction and addressing mode exists. */
4083 if (! validate_change (insn, &XEXP (use, 0),
4084 gen_rtx_fmt_e (amount > 0
4085 ? (do_post ? POST_INC : PRE_INC)
4086 : (do_post ? POST_DEC : PRE_DEC),
4090 /* Record that this insn now has an implicit side effect on X. */
4091 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
4095 #endif /* AUTO_INC_DEC */
4097 /* Find the place in the rtx X where REG is used as a memory address.
4098 Return the MEM rtx that so uses it.
4099 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4100 (plus REG (const_int PLUSCONST)).
4102 If such an address does not appear, return 0.
4103 If REG appears more than once, or is used other than in such an address,
4107 find_use_as_address (x, reg, plusconst)
4110 HOST_WIDE_INT plusconst;
4112 enum rtx_code code = GET_CODE (x);
4113 const char * const fmt = GET_RTX_FORMAT (code);
4118 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
4121 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
4122 && XEXP (XEXP (x, 0), 0) == reg
4123 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
4124 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
4127 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
4129 /* If REG occurs inside a MEM used in a bit-field reference,
4130 that is unacceptable. */
4131 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
4132 return (rtx) (size_t) 1;
4136 return (rtx) (size_t) 1;
4138 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4142 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
4146 return (rtx) (size_t) 1;
4148 else if (fmt[i] == 'E')
4151 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4153 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
4157 return (rtx) (size_t) 1;
4165 /* Write information about registers and basic blocks into FILE.
4166 This is part of making a debugging dump. */
4169 dump_regset (r, outf)
4176 fputs (" (nil)", outf);
4180 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
4182 fprintf (outf, " %d", i);
4183 if (i < FIRST_PSEUDO_REGISTER)
4184 fprintf (outf, " [%s]",
4189 /* Print a human-reaable representation of R on the standard error
4190 stream. This function is designed to be used from within the
4197 dump_regset (r, stderr);
4198 putc ('\n', stderr);
4201 /* Recompute register set/reference counts immediately prior to register
4204 This avoids problems with set/reference counts changing to/from values
4205 which have special meanings to the register allocators.
4207 Additionally, the reference counts are the primary component used by the
4208 register allocators to prioritize pseudos for allocation to hard regs.
4209 More accurate reference counts generally lead to better register allocation.
4211 F is the first insn to be scanned.
4213 LOOP_STEP denotes how much loop_depth should be incremented per
4214 loop nesting level in order to increase the ref count more for
4215 references in a loop.
4217 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4218 possibly other information which is used by the register allocators. */
4221 recompute_reg_usage (f, loop_step)
4222 rtx f ATTRIBUTE_UNUSED;
4223 int loop_step ATTRIBUTE_UNUSED;
4225 allocate_reg_life_data ();
4226 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
4229 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4230 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4231 of the number of registers that died. */
4234 count_or_remove_death_notes (blocks, kill)
4240 for (i = n_basic_blocks - 1; i >= 0; --i)
4245 if (blocks && ! TEST_BIT (blocks, i))
4248 bb = BASIC_BLOCK (i);
4250 for (insn = bb->head;; insn = NEXT_INSN (insn))
4254 rtx *pprev = ®_NOTES (insn);
4259 switch (REG_NOTE_KIND (link))
4262 if (GET_CODE (XEXP (link, 0)) == REG)
4264 rtx reg = XEXP (link, 0);
4267 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
4270 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
4278 rtx next = XEXP (link, 1);
4279 free_EXPR_LIST_node (link);
4280 *pprev = link = next;
4286 pprev = &XEXP (link, 1);
4293 if (insn == bb->end)
4300 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4301 if blocks is NULL. */
4304 clear_log_links (blocks)
4312 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4314 free_INSN_LIST_list (&LOG_LINKS (insn));
4317 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4319 basic_block bb = BASIC_BLOCK (i);
4321 for (insn = bb->head; insn != NEXT_INSN (bb->end);
4322 insn = NEXT_INSN (insn))
4324 free_INSN_LIST_list (&LOG_LINKS (insn));
4328 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4329 correspond to the hard registers, if any, set in that map. This
4330 could be done far more efficiently by having all sorts of special-cases
4331 with moving single words, but probably isn't worth the trouble. */
4334 reg_set_to_hard_reg_set (to, from)
4340 EXECUTE_IF_SET_IN_BITMAP
4343 if (i >= FIRST_PSEUDO_REGISTER)
4345 SET_HARD_REG_BIT (*to, i);