1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002 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 /* Number of dead insns removed. */
285 /* Maximum length of pbi->mem_set_list before we start dropping
286 new elements on the floor. */
287 #define MAX_MEM_SET_LIST_LEN 100
289 /* Forward declarations */
290 static int verify_wide_reg_1 PARAMS ((rtx *, void *));
291 static void verify_wide_reg PARAMS ((int, basic_block));
292 static void verify_local_live_at_start PARAMS ((regset, basic_block));
293 static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *));
294 static void notice_stack_pointer_modification PARAMS ((rtx));
295 static void mark_reg PARAMS ((rtx, void *));
296 static void mark_regs_live_at_end PARAMS ((regset));
297 static int set_phi_alternative_reg PARAMS ((rtx, int, int, void *));
298 static void calculate_global_regs_live PARAMS ((sbitmap, sbitmap, int));
299 static void propagate_block_delete_insn PARAMS ((rtx));
300 static rtx propagate_block_delete_libcall PARAMS ((rtx, rtx));
301 static int insn_dead_p PARAMS ((struct propagate_block_info *,
303 static int libcall_dead_p PARAMS ((struct propagate_block_info *,
305 static void mark_set_regs PARAMS ((struct propagate_block_info *,
307 static void mark_set_1 PARAMS ((struct propagate_block_info *,
308 enum rtx_code, rtx, rtx,
310 static int find_regno_partial PARAMS ((rtx *, void *));
312 #ifdef HAVE_conditional_execution
313 static int mark_regno_cond_dead PARAMS ((struct propagate_block_info *,
315 static void free_reg_cond_life_info PARAMS ((splay_tree_value));
316 static int flush_reg_cond_reg_1 PARAMS ((splay_tree_node, void *));
317 static void flush_reg_cond_reg PARAMS ((struct propagate_block_info *,
319 static rtx elim_reg_cond PARAMS ((rtx, unsigned int));
320 static rtx ior_reg_cond PARAMS ((rtx, rtx, int));
321 static rtx not_reg_cond PARAMS ((rtx));
322 static rtx and_reg_cond PARAMS ((rtx, rtx, int));
325 static void attempt_auto_inc PARAMS ((struct propagate_block_info *,
326 rtx, rtx, rtx, rtx, rtx));
327 static void find_auto_inc PARAMS ((struct propagate_block_info *,
329 static int try_pre_increment_1 PARAMS ((struct propagate_block_info *,
331 static int try_pre_increment PARAMS ((rtx, rtx, HOST_WIDE_INT));
333 static void mark_used_reg PARAMS ((struct propagate_block_info *,
335 static void mark_used_regs PARAMS ((struct propagate_block_info *,
337 void dump_flow_info PARAMS ((FILE *));
338 void debug_flow_info PARAMS ((void));
339 static void add_to_mem_set_list PARAMS ((struct propagate_block_info *,
341 static void invalidate_mems_from_autoinc PARAMS ((struct propagate_block_info *,
343 static void invalidate_mems_from_set PARAMS ((struct propagate_block_info *,
345 static void clear_log_links PARAMS ((sbitmap));
349 check_function_return_warnings ()
351 if (warn_missing_noreturn
352 && !TREE_THIS_VOLATILE (cfun->decl)
353 && EXIT_BLOCK_PTR->pred == NULL
354 && (lang_missing_noreturn_ok_p
355 && !lang_missing_noreturn_ok_p (cfun->decl)))
356 warning ("function might be possible candidate for attribute `noreturn'");
358 /* If we have a path to EXIT, then we do return. */
359 if (TREE_THIS_VOLATILE (cfun->decl)
360 && EXIT_BLOCK_PTR->pred != NULL)
361 warning ("`noreturn' function does return");
363 /* If the clobber_return_insn appears in some basic block, then we
364 do reach the end without returning a value. */
365 else if (warn_return_type
366 && cfun->x_clobber_return_insn != NULL
367 && EXIT_BLOCK_PTR->pred != NULL)
369 int max_uid = get_max_uid ();
371 /* If clobber_return_insn was excised by jump1, then renumber_insns
372 can make max_uid smaller than the number still recorded in our rtx.
373 That's fine, since this is a quick way of verifying that the insn
374 is no longer in the chain. */
375 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
377 /* Recompute insn->block mapping, since the initial mapping is
378 set before we delete unreachable blocks. */
379 if (BLOCK_FOR_INSN (cfun->x_clobber_return_insn) != NULL)
380 warning ("control reaches end of non-void function");
385 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
386 note associated with the BLOCK. */
389 first_insn_after_basic_block_note (block)
394 /* Get the first instruction in the block. */
397 if (insn == NULL_RTX)
399 if (GET_CODE (insn) == CODE_LABEL)
400 insn = NEXT_INSN (insn);
401 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
404 return NEXT_INSN (insn);
407 /* Perform data flow analysis.
408 F is the first insn of the function; FLAGS is a set of PROP_* flags
409 to be used in accumulating flow info. */
412 life_analysis (f, file, flags)
417 #ifdef ELIMINABLE_REGS
419 static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS;
422 /* Record which registers will be eliminated. We use this in
425 CLEAR_HARD_REG_SET (elim_reg_set);
427 #ifdef ELIMINABLE_REGS
428 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
429 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
431 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
435 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES);
437 /* The post-reload life analysis have (on a global basis) the same
438 registers live as was computed by reload itself. elimination
439 Otherwise offsets and such may be incorrect.
441 Reload will make some registers as live even though they do not
444 We don't want to create new auto-incs after reload, since they
445 are unlikely to be useful and can cause problems with shared
447 if (reload_completed)
448 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
450 /* We want alias analysis information for local dead store elimination. */
451 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
452 init_alias_analysis ();
454 /* Always remove no-op moves. Do this before other processing so
455 that we don't have to keep re-scanning them. */
456 delete_noop_moves (f);
458 /* Some targets can emit simpler epilogues if they know that sp was
459 not ever modified during the function. After reload, of course,
460 we've already emitted the epilogue so there's no sense searching. */
461 if (! reload_completed)
462 notice_stack_pointer_modification (f);
464 /* Allocate and zero out data structures that will record the
465 data from lifetime analysis. */
466 allocate_reg_life_data ();
467 allocate_bb_life_data ();
469 /* Find the set of registers live on function exit. */
470 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
472 /* "Update" life info from zero. It'd be nice to begin the
473 relaxation with just the exit and noreturn blocks, but that set
474 is not immediately handy. */
476 if (flags & PROP_REG_INFO)
477 memset (regs_ever_live, 0, sizeof (regs_ever_live));
478 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
481 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
482 end_alias_analysis ();
485 dump_flow_info (file);
487 free_basic_block_vars (1);
489 #ifdef ENABLE_CHECKING
493 /* Search for any REG_LABEL notes which reference deleted labels. */
494 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
496 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
498 if (inote && GET_CODE (inote) == NOTE_INSN_DELETED_LABEL)
503 /* Removing dead insns should've made jumptables really dead. */
504 delete_dead_jumptables ();
507 /* A subroutine of verify_wide_reg, called through for_each_rtx.
508 Search for REGNO. If found, return 2 if it is not wider than
512 verify_wide_reg_1 (px, pregno)
517 unsigned int regno = *(int *) pregno;
519 if (GET_CODE (x) == REG && REGNO (x) == regno)
521 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
528 /* A subroutine of verify_local_live_at_start. Search through insns
529 of BB looking for register REGNO. */
532 verify_wide_reg (regno, bb)
536 rtx head = bb->head, end = bb->end;
542 int r = for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no);
550 head = NEXT_INSN (head);
555 fprintf (rtl_dump_file, "Register %d died unexpectedly.\n", regno);
556 dump_bb (bb, rtl_dump_file);
561 /* A subroutine of update_life_info. Verify that there are no untoward
562 changes in live_at_start during a local update. */
565 verify_local_live_at_start (new_live_at_start, bb)
566 regset new_live_at_start;
569 if (reload_completed)
571 /* After reload, there are no pseudos, nor subregs of multi-word
572 registers. The regsets should exactly match. */
573 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
577 fprintf (rtl_dump_file,
578 "live_at_start mismatch in bb %d, aborting\nNew:\n",
580 debug_bitmap_file (rtl_dump_file, new_live_at_start);
581 fputs ("Old:\n", rtl_dump_file);
582 dump_bb (bb, rtl_dump_file);
591 /* Find the set of changed registers. */
592 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
594 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
596 /* No registers should die. */
597 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
601 fprintf (rtl_dump_file,
602 "Register %d died unexpectedly.\n", i);
603 dump_bb (bb, rtl_dump_file);
608 /* Verify that the now-live register is wider than word_mode. */
609 verify_wide_reg (i, bb);
614 /* Updates life information starting with the basic blocks set in BLOCKS.
615 If BLOCKS is null, consider it to be the universal set.
617 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholeing,
618 we are only expecting local modifications to basic blocks. If we find
619 extra registers live at the beginning of a block, then we either killed
620 useful data, or we have a broken split that wants data not provided.
621 If we find registers removed from live_at_start, that means we have
622 a broken peephole that is killing a register it shouldn't.
624 ??? This is not true in one situation -- when a pre-reload splitter
625 generates subregs of a multi-word pseudo, current life analysis will
626 lose the kill. So we _can_ have a pseudo go live. How irritating.
628 Including PROP_REG_INFO does not properly refresh regs_ever_live
629 unless the caller resets it to zero. */
632 update_life_info (blocks, extent, prop_flags)
634 enum update_life_extent extent;
638 regset_head tmp_head;
641 tmp = INITIALIZE_REG_SET (tmp_head);
644 timevar_push ((extent == UPDATE_LIFE_LOCAL || blocks)
645 ? TV_LIFE_UPDATE : TV_LIFE);
647 /* Changes to the CFG are only allowed when
648 doing a global update for the entire CFG. */
649 if ((prop_flags & PROP_ALLOW_CFG_CHANGES)
650 && (extent == UPDATE_LIFE_LOCAL || blocks))
653 /* For a global update, we go through the relaxation process again. */
654 if (extent != UPDATE_LIFE_LOCAL)
660 calculate_global_regs_live (blocks, blocks,
661 prop_flags & (PROP_SCAN_DEAD_CODE
662 | PROP_ALLOW_CFG_CHANGES));
664 if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
665 != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
668 /* Removing dead code may allow the CFG to be simplified which
669 in turn may allow for further dead code detection / removal. */
670 for (i = n_basic_blocks - 1; i >= 0; --i)
672 basic_block bb = BASIC_BLOCK (i);
674 COPY_REG_SET (tmp, bb->global_live_at_end);
675 changed |= propagate_block (bb, tmp, NULL, NULL,
676 prop_flags & (PROP_SCAN_DEAD_CODE
677 | PROP_KILL_DEAD_CODE));
680 if (! changed || ! cleanup_cfg (CLEANUP_EXPENSIVE))
684 /* If asked, remove notes from the blocks we'll update. */
685 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
686 count_or_remove_death_notes (blocks, 1);
689 /* Clear log links in case we are asked to (re)compute them. */
690 if (prop_flags & PROP_LOG_LINKS)
691 clear_log_links (blocks);
695 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
697 basic_block bb = BASIC_BLOCK (i);
699 COPY_REG_SET (tmp, bb->global_live_at_end);
700 propagate_block (bb, tmp, NULL, NULL, prop_flags);
702 if (extent == UPDATE_LIFE_LOCAL)
703 verify_local_live_at_start (tmp, bb);
708 for (i = n_basic_blocks - 1; i >= 0; --i)
710 basic_block bb = BASIC_BLOCK (i);
712 COPY_REG_SET (tmp, bb->global_live_at_end);
713 propagate_block (bb, tmp, NULL, NULL, prop_flags);
715 if (extent == UPDATE_LIFE_LOCAL)
716 verify_local_live_at_start (tmp, bb);
722 if (prop_flags & PROP_REG_INFO)
724 /* The only pseudos that are live at the beginning of the function
725 are those that were not set anywhere in the function. local-alloc
726 doesn't know how to handle these correctly, so mark them as not
727 local to any one basic block. */
728 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
729 FIRST_PSEUDO_REGISTER, i,
730 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
732 /* We have a problem with any pseudoreg that lives across the setjmp.
733 ANSI says that if a user variable does not change in value between
734 the setjmp and the longjmp, then the longjmp preserves it. This
735 includes longjmp from a place where the pseudo appears dead.
736 (In principle, the value still exists if it is in scope.)
737 If the pseudo goes in a hard reg, some other value may occupy
738 that hard reg where this pseudo is dead, thus clobbering the pseudo.
739 Conclusion: such a pseudo must not go in a hard reg. */
740 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
741 FIRST_PSEUDO_REGISTER, i,
743 if (regno_reg_rtx[i] != 0)
745 REG_LIVE_LENGTH (i) = -1;
746 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
750 timevar_pop ((extent == UPDATE_LIFE_LOCAL || blocks)
751 ? TV_LIFE_UPDATE : TV_LIFE);
752 if (ndead && rtl_dump_file)
753 fprintf (rtl_dump_file, "deleted %i dead insns\n", ndead);
757 /* Update life information in all blocks where BB_DIRTY is set. */
760 update_life_info_in_dirty_blocks (extent, prop_flags)
761 enum update_life_extent extent;
764 sbitmap update_life_blocks = sbitmap_alloc (n_basic_blocks);
769 sbitmap_zero (update_life_blocks);
770 for (block_num = 0; block_num < n_basic_blocks; block_num++)
771 if (BASIC_BLOCK (block_num)->flags & BB_DIRTY)
773 SET_BIT (update_life_blocks, block_num);
778 retval = update_life_info (update_life_blocks, extent, prop_flags);
780 sbitmap_free (update_life_blocks);
784 /* Free the variables allocated by find_basic_blocks.
786 KEEP_HEAD_END_P is non-zero if basic_block_info is not to be freed. */
789 free_basic_block_vars (keep_head_end_p)
792 if (! keep_head_end_p)
794 if (basic_block_info)
797 VARRAY_FREE (basic_block_info);
801 ENTRY_BLOCK_PTR->aux = NULL;
802 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
803 EXIT_BLOCK_PTR->aux = NULL;
804 EXIT_BLOCK_PTR->global_live_at_start = NULL;
808 /* Delete any insns that copy a register to itself. */
811 delete_noop_moves (f)
812 rtx f ATTRIBUTE_UNUSED;
819 for (i = 0; i < n_basic_blocks; i++)
821 bb = BASIC_BLOCK (i);
822 for (insn = bb->head; insn != NEXT_INSN (bb->end); insn = next)
824 next = NEXT_INSN (insn);
825 if (INSN_P (insn) && noop_move_p (insn))
829 /* If we're about to remove the first insn of a libcall
830 then move the libcall note to the next real insn and
831 update the retval note. */
832 if ((note = find_reg_note (insn, REG_LIBCALL, NULL_RTX))
833 && XEXP (note, 0) != insn)
835 rtx new_libcall_insn = next_real_insn (insn);
836 rtx retval_note = find_reg_note (XEXP (note, 0),
837 REG_RETVAL, NULL_RTX);
838 REG_NOTES (new_libcall_insn)
839 = gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0),
840 REG_NOTES (new_libcall_insn));
841 XEXP (retval_note, 0) = new_libcall_insn;
844 delete_insn_and_edges (insn);
849 if (nnoops && rtl_dump_file)
850 fprintf (rtl_dump_file, "deleted %i noop moves", nnoops);
854 /* Delete any jump tables never referenced. We can't delete them at the
855 time of removing tablejump insn as they are referenced by the preceding
856 insns computing the destination, so we delay deleting and garbagecollect
857 them once life information is computed. */
859 delete_dead_jumptables ()
862 for (insn = get_insns (); insn; insn = next)
864 next = NEXT_INSN (insn);
865 if (GET_CODE (insn) == CODE_LABEL
866 && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
867 && GET_CODE (next) == JUMP_INSN
868 && (GET_CODE (PATTERN (next)) == ADDR_VEC
869 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
872 fprintf (rtl_dump_file, "Dead jumptable %i removed\n", INSN_UID (insn));
873 delete_insn (NEXT_INSN (insn));
875 next = NEXT_INSN (next);
880 /* Determine if the stack pointer is constant over the life of the function.
881 Only useful before prologues have been emitted. */
884 notice_stack_pointer_modification_1 (x, pat, data)
886 rtx pat ATTRIBUTE_UNUSED;
887 void *data ATTRIBUTE_UNUSED;
889 if (x == stack_pointer_rtx
890 /* The stack pointer is only modified indirectly as the result
891 of a push until later in flow. See the comments in rtl.texi
892 regarding Embedded Side-Effects on Addresses. */
893 || (GET_CODE (x) == MEM
894 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
895 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
896 current_function_sp_is_unchanging = 0;
900 notice_stack_pointer_modification (f)
905 /* Assume that the stack pointer is unchanging if alloca hasn't
907 current_function_sp_is_unchanging = !current_function_calls_alloca;
908 if (! current_function_sp_is_unchanging)
911 for (insn = f; insn; insn = NEXT_INSN (insn))
915 /* Check if insn modifies the stack pointer. */
916 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
918 if (! current_function_sp_is_unchanging)
924 /* Mark a register in SET. Hard registers in large modes get all
925 of their component registers set as well. */
932 regset set = (regset) xset;
933 int regno = REGNO (reg);
935 if (GET_MODE (reg) == BLKmode)
938 SET_REGNO_REG_SET (set, regno);
939 if (regno < FIRST_PSEUDO_REGISTER)
941 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
943 SET_REGNO_REG_SET (set, regno + n);
947 /* Mark those regs which are needed at the end of the function as live
948 at the end of the last basic block. */
951 mark_regs_live_at_end (set)
956 /* If exiting needs the right stack value, consider the stack pointer
957 live at the end of the function. */
958 if ((HAVE_epilogue && reload_completed)
959 || ! EXIT_IGNORE_STACK
960 || (! FRAME_POINTER_REQUIRED
961 && ! current_function_calls_alloca
962 && flag_omit_frame_pointer)
963 || current_function_sp_is_unchanging)
965 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
968 /* Mark the frame pointer if needed at the end of the function. If
969 we end up eliminating it, it will be removed from the live list
970 of each basic block by reload. */
972 if (! reload_completed || frame_pointer_needed)
974 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
975 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
976 /* If they are different, also mark the hard frame pointer as live. */
977 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
978 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
982 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
983 /* Many architectures have a GP register even without flag_pic.
984 Assume the pic register is not in use, or will be handled by
985 other means, if it is not fixed. */
986 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
987 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
988 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
991 /* Mark all global registers, and all registers used by the epilogue
992 as being live at the end of the function since they may be
993 referenced by our caller. */
994 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
995 if (global_regs[i] || EPILOGUE_USES (i))
996 SET_REGNO_REG_SET (set, i);
998 if (HAVE_epilogue && reload_completed)
1000 /* Mark all call-saved registers that we actually used. */
1001 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1002 if (regs_ever_live[i] && ! LOCAL_REGNO (i)
1003 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1004 SET_REGNO_REG_SET (set, i);
1007 #ifdef EH_RETURN_DATA_REGNO
1008 /* Mark the registers that will contain data for the handler. */
1009 if (reload_completed && current_function_calls_eh_return)
1012 unsigned regno = EH_RETURN_DATA_REGNO(i);
1013 if (regno == INVALID_REGNUM)
1015 SET_REGNO_REG_SET (set, regno);
1018 #ifdef EH_RETURN_STACKADJ_RTX
1019 if ((! HAVE_epilogue || ! reload_completed)
1020 && current_function_calls_eh_return)
1022 rtx tmp = EH_RETURN_STACKADJ_RTX;
1023 if (tmp && REG_P (tmp))
1024 mark_reg (tmp, set);
1027 #ifdef EH_RETURN_HANDLER_RTX
1028 if ((! HAVE_epilogue || ! reload_completed)
1029 && current_function_calls_eh_return)
1031 rtx tmp = EH_RETURN_HANDLER_RTX;
1032 if (tmp && REG_P (tmp))
1033 mark_reg (tmp, set);
1037 /* Mark function return value. */
1038 diddle_return_value (mark_reg, set);
1041 /* Callback function for for_each_successor_phi. DATA is a regset.
1042 Sets the SRC_REGNO, the regno of the phi alternative for phi node
1043 INSN, in the regset. */
1046 set_phi_alternative_reg (insn, dest_regno, src_regno, data)
1047 rtx insn ATTRIBUTE_UNUSED;
1048 int dest_regno ATTRIBUTE_UNUSED;
1052 regset live = (regset) data;
1053 SET_REGNO_REG_SET (live, src_regno);
1057 /* Propagate global life info around the graph of basic blocks. Begin
1058 considering blocks with their corresponding bit set in BLOCKS_IN.
1059 If BLOCKS_IN is null, consider it the universal set.
1061 BLOCKS_OUT is set for every block that was changed. */
1064 calculate_global_regs_live (blocks_in, blocks_out, flags)
1065 sbitmap blocks_in, blocks_out;
1068 basic_block *queue, *qhead, *qtail, *qend;
1069 regset tmp, new_live_at_end, call_used;
1070 regset_head tmp_head, call_used_head;
1071 regset_head new_live_at_end_head;
1074 tmp = INITIALIZE_REG_SET (tmp_head);
1075 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
1076 call_used = INITIALIZE_REG_SET (call_used_head);
1078 /* Inconveniently, this is only readily available in hard reg set form. */
1079 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
1080 if (call_used_regs[i])
1081 SET_REGNO_REG_SET (call_used, i);
1083 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1084 because the `head == tail' style test for an empty queue doesn't
1085 work with a full queue. */
1086 queue = (basic_block *) xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
1088 qhead = qend = queue + n_basic_blocks + 2;
1090 /* Queue the blocks set in the initial mask. Do this in reverse block
1091 number order so that we are more likely for the first round to do
1092 useful work. We use AUX non-null to flag that the block is queued. */
1095 /* Clear out the garbage that might be hanging out in bb->aux. */
1096 for (i = n_basic_blocks - 1; i >= 0; --i)
1097 BASIC_BLOCK (i)->aux = NULL;
1099 EXECUTE_IF_SET_IN_SBITMAP (blocks_in, 0, i,
1101 basic_block bb = BASIC_BLOCK (i);
1108 for (i = 0; i < n_basic_blocks; ++i)
1110 basic_block bb = BASIC_BLOCK (i);
1117 sbitmap_zero (blocks_out);
1119 /* We work through the queue until there are no more blocks. What
1120 is live at the end of this block is precisely the union of what
1121 is live at the beginning of all its successors. So, we set its
1122 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1123 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1124 this block by walking through the instructions in this block in
1125 reverse order and updating as we go. If that changed
1126 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1127 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1129 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1130 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1131 must either be live at the end of the block, or used within the
1132 block. In the latter case, it will certainly never disappear
1133 from GLOBAL_LIVE_AT_START. In the former case, the register
1134 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1135 for one of the successor blocks. By induction, that cannot
1137 while (qhead != qtail)
1139 int rescan, changed;
1148 /* Begin by propagating live_at_start from the successor blocks. */
1149 CLEAR_REG_SET (new_live_at_end);
1152 for (e = bb->succ; e; e = e->succ_next)
1154 basic_block sb = e->dest;
1156 /* Call-clobbered registers die across exception and
1158 /* ??? Abnormal call edges ignored for the moment, as this gets
1159 confused by sibling call edges, which crashes reg-stack. */
1160 if (e->flags & EDGE_EH)
1162 bitmap_operation (tmp, sb->global_live_at_start,
1163 call_used, BITMAP_AND_COMPL);
1164 IOR_REG_SET (new_live_at_end, tmp);
1167 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
1169 /* If a target saves one register in another (instead of on
1170 the stack) the save register will need to be live for EH. */
1171 if (e->flags & EDGE_EH)
1172 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1174 SET_REGNO_REG_SET (new_live_at_end, i);
1178 /* This might be a noreturn function that throws. And
1179 even if it isn't, getting the unwind info right helps
1181 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1183 SET_REGNO_REG_SET (new_live_at_end, i);
1186 /* The all-important stack pointer must always be live. */
1187 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
1189 /* Before reload, there are a few registers that must be forced
1190 live everywhere -- which might not already be the case for
1191 blocks within infinite loops. */
1192 if (! reload_completed)
1194 /* Any reference to any pseudo before reload is a potential
1195 reference of the frame pointer. */
1196 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
1198 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1199 /* Pseudos with argument area equivalences may require
1200 reloading via the argument pointer. */
1201 if (fixed_regs[ARG_POINTER_REGNUM])
1202 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
1205 /* Any constant, or pseudo with constant equivalences, may
1206 require reloading from memory using the pic register. */
1207 if (PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
1208 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
1209 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
1212 /* Regs used in phi nodes are not included in
1213 global_live_at_start, since they are live only along a
1214 particular edge. Set those regs that are live because of a
1215 phi node alternative corresponding to this particular block. */
1217 for_each_successor_phi (bb, &set_phi_alternative_reg,
1220 if (bb == ENTRY_BLOCK_PTR)
1222 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1226 /* On our first pass through this block, we'll go ahead and continue.
1227 Recognize first pass by local_set NULL. On subsequent passes, we
1228 get to skip out early if live_at_end wouldn't have changed. */
1230 if (bb->local_set == NULL)
1232 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1233 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1238 /* If any bits were removed from live_at_end, we'll have to
1239 rescan the block. This wouldn't be necessary if we had
1240 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1241 local_live is really dependent on live_at_end. */
1242 CLEAR_REG_SET (tmp);
1243 rescan = bitmap_operation (tmp, bb->global_live_at_end,
1244 new_live_at_end, BITMAP_AND_COMPL);
1248 /* If any of the registers in the new live_at_end set are
1249 conditionally set in this basic block, we must rescan.
1250 This is because conditional lifetimes at the end of the
1251 block do not just take the live_at_end set into account,
1252 but also the liveness at the start of each successor
1253 block. We can miss changes in those sets if we only
1254 compare the new live_at_end against the previous one. */
1255 CLEAR_REG_SET (tmp);
1256 rescan = bitmap_operation (tmp, new_live_at_end,
1257 bb->cond_local_set, BITMAP_AND);
1262 /* Find the set of changed bits. Take this opportunity
1263 to notice that this set is empty and early out. */
1264 CLEAR_REG_SET (tmp);
1265 changed = bitmap_operation (tmp, bb->global_live_at_end,
1266 new_live_at_end, BITMAP_XOR);
1270 /* If any of the changed bits overlap with local_set,
1271 we'll have to rescan the block. Detect overlap by
1272 the AND with ~local_set turning off bits. */
1273 rescan = bitmap_operation (tmp, tmp, bb->local_set,
1278 /* Let our caller know that BB changed enough to require its
1279 death notes updated. */
1281 SET_BIT (blocks_out, bb->index);
1285 /* Add to live_at_start the set of all registers in
1286 new_live_at_end that aren't in the old live_at_end. */
1288 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
1290 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1292 changed = bitmap_operation (bb->global_live_at_start,
1293 bb->global_live_at_start,
1300 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1302 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1303 into live_at_start. */
1304 propagate_block (bb, new_live_at_end, bb->local_set,
1305 bb->cond_local_set, flags);
1307 /* If live_at start didn't change, no need to go farther. */
1308 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
1311 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
1314 /* Queue all predecessors of BB so that we may re-examine
1315 their live_at_end. */
1316 for (e = bb->pred; e; e = e->pred_next)
1318 basic_block pb = e->src;
1319 if (pb->aux == NULL)
1330 FREE_REG_SET (new_live_at_end);
1331 FREE_REG_SET (call_used);
1335 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
1337 basic_block bb = BASIC_BLOCK (i);
1338 FREE_REG_SET (bb->local_set);
1339 FREE_REG_SET (bb->cond_local_set);
1344 for (i = n_basic_blocks - 1; i >= 0; --i)
1346 basic_block bb = BASIC_BLOCK (i);
1347 FREE_REG_SET (bb->local_set);
1348 FREE_REG_SET (bb->cond_local_set);
1356 /* This structure is used to pass parameters to an from the
1357 the function find_regno_partial(). It is used to pass in the
1358 register number we are looking, as well as to return any rtx
1362 unsigned regno_to_find;
1364 } find_regno_partial_param;
1367 /* Find the rtx for the reg numbers specified in 'data' if it is
1368 part of an expression which only uses part of the register. Return
1369 it in the structure passed in. */
1371 find_regno_partial (ptr, data)
1375 find_regno_partial_param *param = (find_regno_partial_param *)data;
1376 unsigned reg = param->regno_to_find;
1377 param->retval = NULL_RTX;
1379 if (*ptr == NULL_RTX)
1382 switch (GET_CODE (*ptr))
1386 case STRICT_LOW_PART:
1387 if (GET_CODE (XEXP (*ptr, 0)) == REG && REGNO (XEXP (*ptr, 0)) == reg)
1389 param->retval = XEXP (*ptr, 0);
1395 if (GET_CODE (SUBREG_REG (*ptr)) == REG
1396 && REGNO (SUBREG_REG (*ptr)) == reg)
1398 param->retval = SUBREG_REG (*ptr);
1410 /* Process all immediate successors of the entry block looking for pseudo
1411 registers which are live on entry. Find all of those whose first
1412 instance is a partial register reference of some kind, and initialize
1413 them to 0 after the entry block. This will prevent bit sets within
1414 registers whose value is unknown, and may contain some kind of sticky
1415 bits we don't want. */
1418 initialize_uninitialized_subregs ()
1422 int reg, did_something = 0;
1423 find_regno_partial_param param;
1425 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
1427 basic_block bb = e->dest;
1428 regset map = bb->global_live_at_start;
1429 EXECUTE_IF_SET_IN_REG_SET (map,
1430 FIRST_PSEUDO_REGISTER, reg,
1432 int uid = REGNO_FIRST_UID (reg);
1435 /* Find an insn which mentions the register we are looking for.
1436 Its preferable to have an instance of the register's rtl since
1437 there may be various flags set which we need to duplicate.
1438 If we can't find it, its probably an automatic whose initial
1439 value doesn't matter, or hopefully something we don't care about. */
1440 for (i = get_insns (); i && INSN_UID (i) != uid; i = NEXT_INSN (i))
1444 /* Found the insn, now get the REG rtx, if we can. */
1445 param.regno_to_find = reg;
1446 for_each_rtx (&i, find_regno_partial, ¶m);
1447 if (param.retval != NULL_RTX)
1449 insn = gen_move_insn (param.retval,
1450 CONST0_RTX (GET_MODE (param.retval)));
1451 insert_insn_on_edge (insn, e);
1459 commit_edge_insertions ();
1460 return did_something;
1464 /* Subroutines of life analysis. */
1466 /* Allocate the permanent data structures that represent the results
1467 of life analysis. Not static since used also for stupid life analysis. */
1470 allocate_bb_life_data ()
1474 for (i = 0; i < n_basic_blocks; i++)
1476 basic_block bb = BASIC_BLOCK (i);
1478 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1479 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1482 ENTRY_BLOCK_PTR->global_live_at_end
1483 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1484 EXIT_BLOCK_PTR->global_live_at_start
1485 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1487 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1491 allocate_reg_life_data ()
1495 max_regno = max_reg_num ();
1497 /* Recalculate the register space, in case it has grown. Old style
1498 vector oriented regsets would set regset_{size,bytes} here also. */
1499 allocate_reg_info (max_regno, FALSE, FALSE);
1501 /* Reset all the data we'll collect in propagate_block and its
1503 for (i = 0; i < max_regno; i++)
1507 REG_N_DEATHS (i) = 0;
1508 REG_N_CALLS_CROSSED (i) = 0;
1509 REG_LIVE_LENGTH (i) = 0;
1510 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
1514 /* Delete dead instructions for propagate_block. */
1517 propagate_block_delete_insn (insn)
1520 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
1522 /* If the insn referred to a label, and that label was attached to
1523 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1524 pretty much mandatory to delete it, because the ADDR_VEC may be
1525 referencing labels that no longer exist.
1527 INSN may reference a deleted label, particularly when a jump
1528 table has been optimized into a direct jump. There's no
1529 real good way to fix up the reference to the deleted label
1530 when the label is deleted, so we just allow it here.
1532 After dead code elimination is complete, we do search for
1533 any REG_LABEL notes which reference deleted labels as a
1536 if (inote && GET_CODE (inote) == CODE_LABEL)
1538 rtx label = XEXP (inote, 0);
1541 /* The label may be forced if it has been put in the constant
1542 pool. If that is the only use we must discard the table
1543 jump following it, but not the label itself. */
1544 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
1545 && (next = next_nonnote_insn (label)) != NULL
1546 && GET_CODE (next) == JUMP_INSN
1547 && (GET_CODE (PATTERN (next)) == ADDR_VEC
1548 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
1550 rtx pat = PATTERN (next);
1551 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
1552 int len = XVECLEN (pat, diff_vec_p);
1555 for (i = 0; i < len; i++)
1556 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
1558 delete_insn_and_edges (next);
1563 delete_insn_and_edges (insn);
1567 /* Delete dead libcalls for propagate_block. Return the insn
1568 before the libcall. */
1571 propagate_block_delete_libcall ( insn, note)
1574 rtx first = XEXP (note, 0);
1575 rtx before = PREV_INSN (first);
1577 delete_insn_chain_and_edges (first, insn);
1582 /* Update the life-status of regs for one insn. Return the previous insn. */
1585 propagate_one_insn (pbi, insn)
1586 struct propagate_block_info *pbi;
1589 rtx prev = PREV_INSN (insn);
1590 int flags = pbi->flags;
1591 int insn_is_dead = 0;
1592 int libcall_is_dead = 0;
1596 if (! INSN_P (insn))
1599 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1600 if (flags & PROP_SCAN_DEAD_CODE)
1602 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
1603 libcall_is_dead = (insn_is_dead && note != 0
1604 && libcall_dead_p (pbi, note, insn));
1607 /* If an instruction consists of just dead store(s) on final pass,
1609 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
1611 /* If we're trying to delete a prologue or epilogue instruction
1612 that isn't flagged as possibly being dead, something is wrong.
1613 But if we are keeping the stack pointer depressed, we might well
1614 be deleting insns that are used to compute the amount to update
1615 it by, so they are fine. */
1616 if (reload_completed
1617 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1618 && (TYPE_RETURNS_STACK_DEPRESSED
1619 (TREE_TYPE (current_function_decl))))
1620 && (((HAVE_epilogue || HAVE_prologue)
1621 && prologue_epilogue_contains (insn))
1622 || (HAVE_sibcall_epilogue
1623 && sibcall_epilogue_contains (insn)))
1624 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
1625 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn);
1627 /* Record sets. Do this even for dead instructions, since they
1628 would have killed the values if they hadn't been deleted. */
1629 mark_set_regs (pbi, PATTERN (insn), insn);
1631 /* CC0 is now known to be dead. Either this insn used it,
1632 in which case it doesn't anymore, or clobbered it,
1633 so the next insn can't use it. */
1636 if (libcall_is_dead)
1637 prev = propagate_block_delete_libcall ( insn, note);
1639 propagate_block_delete_insn (insn);
1644 /* See if this is an increment or decrement that can be merged into
1645 a following memory address. */
1648 rtx x = single_set (insn);
1650 /* Does this instruction increment or decrement a register? */
1651 if ((flags & PROP_AUTOINC)
1653 && GET_CODE (SET_DEST (x)) == REG
1654 && (GET_CODE (SET_SRC (x)) == PLUS
1655 || GET_CODE (SET_SRC (x)) == MINUS)
1656 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1657 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1658 /* Ok, look for a following memory ref we can combine with.
1659 If one is found, change the memory ref to a PRE_INC
1660 or PRE_DEC, cancel this insn, and return 1.
1661 Return 0 if nothing has been done. */
1662 && try_pre_increment_1 (pbi, insn))
1665 #endif /* AUTO_INC_DEC */
1667 CLEAR_REG_SET (pbi->new_set);
1669 /* If this is not the final pass, and this insn is copying the value of
1670 a library call and it's dead, don't scan the insns that perform the
1671 library call, so that the call's arguments are not marked live. */
1672 if (libcall_is_dead)
1674 /* Record the death of the dest reg. */
1675 mark_set_regs (pbi, PATTERN (insn), insn);
1677 insn = XEXP (note, 0);
1678 return PREV_INSN (insn);
1680 else if (GET_CODE (PATTERN (insn)) == SET
1681 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1682 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1683 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1684 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1685 /* We have an insn to pop a constant amount off the stack.
1686 (Such insns use PLUS regardless of the direction of the stack,
1687 and any insn to adjust the stack by a constant is always a pop.)
1688 These insns, if not dead stores, have no effect on life. */
1693 /* Any regs live at the time of a call instruction must not go
1694 in a register clobbered by calls. Find all regs now live and
1695 record this for them. */
1697 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
1698 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
1699 { REG_N_CALLS_CROSSED (i)++; });
1701 /* Record sets. Do this even for dead instructions, since they
1702 would have killed the values if they hadn't been deleted. */
1703 mark_set_regs (pbi, PATTERN (insn), insn);
1705 if (GET_CODE (insn) == CALL_INSN)
1711 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1712 cond = COND_EXEC_TEST (PATTERN (insn));
1714 /* Non-constant calls clobber memory. */
1715 if (! CONST_OR_PURE_CALL_P (insn))
1717 free_EXPR_LIST_list (&pbi->mem_set_list);
1718 pbi->mem_set_list_len = 0;
1721 /* There may be extra registers to be clobbered. */
1722 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1724 note = XEXP (note, 1))
1725 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
1726 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
1727 cond, insn, pbi->flags);
1729 /* Calls change all call-used and global registers. */
1730 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1731 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1733 /* We do not want REG_UNUSED notes for these registers. */
1734 mark_set_1 (pbi, CLOBBER, gen_rtx_REG (reg_raw_mode[i], i),
1736 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
1740 /* If an insn doesn't use CC0, it becomes dead since we assume
1741 that every insn clobbers it. So show it dead here;
1742 mark_used_regs will set it live if it is referenced. */
1747 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
1748 if ((flags & PROP_EQUAL_NOTES)
1749 && ((note = find_reg_note (insn, REG_EQUAL, NULL_RTX))
1750 || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX))))
1751 mark_used_regs (pbi, XEXP (note, 0), NULL_RTX, insn);
1753 /* Sometimes we may have inserted something before INSN (such as a move)
1754 when we make an auto-inc. So ensure we will scan those insns. */
1756 prev = PREV_INSN (insn);
1759 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1765 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1766 cond = COND_EXEC_TEST (PATTERN (insn));
1768 /* Calls use their arguments. */
1769 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1771 note = XEXP (note, 1))
1772 if (GET_CODE (XEXP (note, 0)) == USE)
1773 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0),
1776 /* The stack ptr is used (honorarily) by a CALL insn. */
1777 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
1779 /* Calls may also reference any of the global registers,
1780 so they are made live. */
1781 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1783 mark_used_reg (pbi, gen_rtx_REG (reg_raw_mode[i], i),
1788 /* On final pass, update counts of how many insns in which each reg
1790 if (flags & PROP_REG_INFO)
1791 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
1792 { REG_LIVE_LENGTH (i)++; });
1797 /* Initialize a propagate_block_info struct for public consumption.
1798 Note that the structure itself is opaque to this file, but that
1799 the user can use the regsets provided here. */
1801 struct propagate_block_info *
1802 init_propagate_block_info (bb, live, local_set, cond_local_set, flags)
1804 regset live, local_set, cond_local_set;
1807 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
1810 pbi->reg_live = live;
1811 pbi->mem_set_list = NULL_RTX;
1812 pbi->mem_set_list_len = 0;
1813 pbi->local_set = local_set;
1814 pbi->cond_local_set = cond_local_set;
1818 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
1819 pbi->reg_next_use = (rtx *) xcalloc (max_reg_num (), sizeof (rtx));
1821 pbi->reg_next_use = NULL;
1823 pbi->new_set = BITMAP_XMALLOC ();
1825 #ifdef HAVE_conditional_execution
1826 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
1827 free_reg_cond_life_info);
1828 pbi->reg_cond_reg = BITMAP_XMALLOC ();
1830 /* If this block ends in a conditional branch, for each register live
1831 from one side of the branch and not the other, record the register
1832 as conditionally dead. */
1833 if (GET_CODE (bb->end) == JUMP_INSN
1834 && any_condjump_p (bb->end))
1836 regset_head diff_head;
1837 regset diff = INITIALIZE_REG_SET (diff_head);
1838 basic_block bb_true, bb_false;
1839 rtx cond_true, cond_false, set_src;
1842 /* Identify the successor blocks. */
1843 bb_true = bb->succ->dest;
1844 if (bb->succ->succ_next != NULL)
1846 bb_false = bb->succ->succ_next->dest;
1848 if (bb->succ->flags & EDGE_FALLTHRU)
1850 basic_block t = bb_false;
1854 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
1859 /* This can happen with a conditional jump to the next insn. */
1860 if (JUMP_LABEL (bb->end) != bb_true->head)
1863 /* Simplest way to do nothing. */
1867 /* Extract the condition from the branch. */
1868 set_src = SET_SRC (pc_set (bb->end));
1869 cond_true = XEXP (set_src, 0);
1870 cond_false = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
1871 GET_MODE (cond_true), XEXP (cond_true, 0),
1872 XEXP (cond_true, 1));
1873 if (GET_CODE (XEXP (set_src, 1)) == PC)
1876 cond_false = cond_true;
1880 /* Compute which register lead different lives in the successors. */
1881 if (bitmap_operation (diff, bb_true->global_live_at_start,
1882 bb_false->global_live_at_start, BITMAP_XOR))
1884 rtx reg = XEXP (cond_true, 0);
1886 if (GET_CODE (reg) == SUBREG)
1887 reg = SUBREG_REG (reg);
1889 if (GET_CODE (reg) != REG)
1892 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
1894 /* For each such register, mark it conditionally dead. */
1895 EXECUTE_IF_SET_IN_REG_SET
1898 struct reg_cond_life_info *rcli;
1901 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
1903 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
1907 rcli->condition = cond;
1908 rcli->stores = const0_rtx;
1909 rcli->orig_condition = cond;
1911 splay_tree_insert (pbi->reg_cond_dead, i,
1912 (splay_tree_value) rcli);
1916 FREE_REG_SET (diff);
1920 /* If this block has no successors, any stores to the frame that aren't
1921 used later in the block are dead. So make a pass over the block
1922 recording any such that are made and show them dead at the end. We do
1923 a very conservative and simple job here. */
1925 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1926 && (TYPE_RETURNS_STACK_DEPRESSED
1927 (TREE_TYPE (current_function_decl))))
1928 && (flags & PROP_SCAN_DEAD_CODE)
1929 && (bb->succ == NULL
1930 || (bb->succ->succ_next == NULL
1931 && bb->succ->dest == EXIT_BLOCK_PTR
1932 && ! current_function_calls_eh_return)))
1935 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
1936 if (GET_CODE (insn) == INSN
1937 && (set = single_set (insn))
1938 && GET_CODE (SET_DEST (set)) == MEM)
1940 rtx mem = SET_DEST (set);
1941 rtx canon_mem = canon_rtx (mem);
1943 /* This optimization is performed by faking a store to the
1944 memory at the end of the block. This doesn't work for
1945 unchanging memories because multiple stores to unchanging
1946 memory is illegal and alias analysis doesn't consider it. */
1947 if (RTX_UNCHANGING_P (canon_mem))
1950 if (XEXP (canon_mem, 0) == frame_pointer_rtx
1951 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
1952 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
1953 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
1954 add_to_mem_set_list (pbi, canon_mem);
1961 /* Release a propagate_block_info struct. */
1964 free_propagate_block_info (pbi)
1965 struct propagate_block_info *pbi;
1967 free_EXPR_LIST_list (&pbi->mem_set_list);
1969 BITMAP_XFREE (pbi->new_set);
1971 #ifdef HAVE_conditional_execution
1972 splay_tree_delete (pbi->reg_cond_dead);
1973 BITMAP_XFREE (pbi->reg_cond_reg);
1976 if (pbi->reg_next_use)
1977 free (pbi->reg_next_use);
1982 /* Compute the registers live at the beginning of a basic block BB from
1983 those live at the end.
1985 When called, REG_LIVE contains those live at the end. On return, it
1986 contains those live at the beginning.
1988 LOCAL_SET, if non-null, will be set with all registers killed
1989 unconditionally by this basic block.
1990 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
1991 killed conditionally by this basic block. If there is any unconditional
1992 set of a register, then the corresponding bit will be set in LOCAL_SET
1993 and cleared in COND_LOCAL_SET.
1994 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
1995 case, the resulting set will be equal to the union of the two sets that
1996 would otherwise be computed.
1998 Return non-zero if an INSN is deleted (i.e. by dead code removal). */
2001 propagate_block (bb, live, local_set, cond_local_set, flags)
2005 regset cond_local_set;
2008 struct propagate_block_info *pbi;
2012 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
2014 if (flags & PROP_REG_INFO)
2018 /* Process the regs live at the end of the block.
2019 Mark them as not local to any one basic block. */
2020 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
2021 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
2024 /* Scan the block an insn at a time from end to beginning. */
2027 for (insn = bb->end;; insn = prev)
2029 /* If this is a call to `setjmp' et al, warn if any
2030 non-volatile datum is live. */
2031 if ((flags & PROP_REG_INFO)
2032 && GET_CODE (insn) == CALL_INSN
2033 && find_reg_note (insn, REG_SETJMP, NULL))
2034 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
2036 prev = propagate_one_insn (pbi, insn);
2037 changed |= NEXT_INSN (prev) != insn;
2039 if (insn == bb->head)
2043 free_propagate_block_info (pbi);
2048 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2049 (SET expressions whose destinations are registers dead after the insn).
2050 NEEDED is the regset that says which regs are alive after the insn.
2052 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL.
2054 If X is the entire body of an insn, NOTES contains the reg notes
2055 pertaining to the insn. */
2058 insn_dead_p (pbi, x, call_ok, notes)
2059 struct propagate_block_info *pbi;
2062 rtx notes ATTRIBUTE_UNUSED;
2064 enum rtx_code code = GET_CODE (x);
2067 /* As flow is invoked after combine, we must take existing AUTO_INC
2068 expressions into account. */
2069 for (; notes; notes = XEXP (notes, 1))
2071 if (REG_NOTE_KIND (notes) == REG_INC)
2073 int regno = REGNO (XEXP (notes, 0));
2075 /* Don't delete insns to set global regs. */
2076 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2077 || REGNO_REG_SET_P (pbi->reg_live, regno))
2083 /* If setting something that's a reg or part of one,
2084 see if that register's altered value will be live. */
2088 rtx r = SET_DEST (x);
2091 if (GET_CODE (r) == CC0)
2092 return ! pbi->cc0_live;
2095 /* A SET that is a subroutine call cannot be dead. */
2096 if (GET_CODE (SET_SRC (x)) == CALL)
2102 /* Don't eliminate loads from volatile memory or volatile asms. */
2103 else if (volatile_refs_p (SET_SRC (x)))
2106 if (GET_CODE (r) == MEM)
2110 if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode)
2113 canon_r = canon_rtx (r);
2115 /* Walk the set of memory locations we are currently tracking
2116 and see if one is an identical match to this memory location.
2117 If so, this memory write is dead (remember, we're walking
2118 backwards from the end of the block to the start). Since
2119 rtx_equal_p does not check the alias set or flags, we also
2120 must have the potential for them to conflict (anti_dependence). */
2121 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
2122 if (anti_dependence (r, XEXP (temp, 0)))
2124 rtx mem = XEXP (temp, 0);
2126 if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0))
2127 && (GET_MODE_SIZE (GET_MODE (canon_r))
2128 <= GET_MODE_SIZE (GET_MODE (mem))))
2132 /* Check if memory reference matches an auto increment. Only
2133 post increment/decrement or modify are valid. */
2134 if (GET_MODE (mem) == GET_MODE (r)
2135 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
2136 || GET_CODE (XEXP (mem, 0)) == POST_INC
2137 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
2138 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
2139 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
2146 while (GET_CODE (r) == SUBREG
2147 || GET_CODE (r) == STRICT_LOW_PART
2148 || GET_CODE (r) == ZERO_EXTRACT)
2151 if (GET_CODE (r) == REG)
2153 int regno = REGNO (r);
2156 if (REGNO_REG_SET_P (pbi->reg_live, regno))
2159 /* If this is a hard register, verify that subsequent
2160 words are not needed. */
2161 if (regno < FIRST_PSEUDO_REGISTER)
2163 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
2166 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
2170 /* Don't delete insns to set global regs. */
2171 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2174 /* Make sure insns to set the stack pointer aren't deleted. */
2175 if (regno == STACK_POINTER_REGNUM)
2178 /* ??? These bits might be redundant with the force live bits
2179 in calculate_global_regs_live. We would delete from
2180 sequential sets; whether this actually affects real code
2181 for anything but the stack pointer I don't know. */
2182 /* Make sure insns to set the frame pointer aren't deleted. */
2183 if (regno == FRAME_POINTER_REGNUM
2184 && (! reload_completed || frame_pointer_needed))
2186 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2187 if (regno == HARD_FRAME_POINTER_REGNUM
2188 && (! reload_completed || frame_pointer_needed))
2192 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2193 /* Make sure insns to set arg pointer are never deleted
2194 (if the arg pointer isn't fixed, there will be a USE
2195 for it, so we can treat it normally). */
2196 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2200 /* Otherwise, the set is dead. */
2206 /* If performing several activities, insn is dead if each activity
2207 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2208 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2210 else if (code == PARALLEL)
2212 int i = XVECLEN (x, 0);
2214 for (i--; i >= 0; i--)
2215 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
2216 && GET_CODE (XVECEXP (x, 0, i)) != USE
2217 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
2223 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2224 is not necessarily true for hard registers. */
2225 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
2226 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
2227 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
2230 /* We do not check other CLOBBER or USE here. An insn consisting of just
2231 a CLOBBER or just a USE should not be deleted. */
2235 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2236 return 1 if the entire library call is dead.
2237 This is true if INSN copies a register (hard or pseudo)
2238 and if the hard return reg of the call insn is dead.
2239 (The caller should have tested the destination of the SET inside
2240 INSN already for death.)
2242 If this insn doesn't just copy a register, then we don't
2243 have an ordinary libcall. In that case, cse could not have
2244 managed to substitute the source for the dest later on,
2245 so we can assume the libcall is dead.
2247 PBI is the block info giving pseudoregs live before this insn.
2248 NOTE is the REG_RETVAL note of the insn. */
2251 libcall_dead_p (pbi, note, insn)
2252 struct propagate_block_info *pbi;
2256 rtx x = single_set (insn);
2260 rtx r = SET_SRC (x);
2262 if (GET_CODE (r) == REG)
2264 rtx call = XEXP (note, 0);
2268 /* Find the call insn. */
2269 while (call != insn && GET_CODE (call) != CALL_INSN)
2270 call = NEXT_INSN (call);
2272 /* If there is none, do nothing special,
2273 since ordinary death handling can understand these insns. */
2277 /* See if the hard reg holding the value is dead.
2278 If this is a PARALLEL, find the call within it. */
2279 call_pat = PATTERN (call);
2280 if (GET_CODE (call_pat) == PARALLEL)
2282 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
2283 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
2284 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
2287 /* This may be a library call that is returning a value
2288 via invisible pointer. Do nothing special, since
2289 ordinary death handling can understand these insns. */
2293 call_pat = XVECEXP (call_pat, 0, i);
2296 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
2302 /* Return 1 if register REGNO was used before it was set, i.e. if it is
2303 live at function entry. Don't count global register variables, variables
2304 in registers that can be used for function arg passing, or variables in
2305 fixed hard registers. */
2308 regno_uninitialized (regno)
2311 if (n_basic_blocks == 0
2312 || (regno < FIRST_PSEUDO_REGISTER
2313 && (global_regs[regno]
2314 || fixed_regs[regno]
2315 || FUNCTION_ARG_REGNO_P (regno))))
2318 return REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno);
2321 /* 1 if register REGNO was alive at a place where `setjmp' was called
2322 and was set more than once or is an argument.
2323 Such regs may be clobbered by `longjmp'. */
2326 regno_clobbered_at_setjmp (regno)
2329 if (n_basic_blocks == 0)
2332 return ((REG_N_SETS (regno) > 1
2333 || REGNO_REG_SET_P (BASIC_BLOCK (0)->global_live_at_start, regno))
2334 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
2337 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2338 maximal list size; look for overlaps in mode and select the largest. */
2340 add_to_mem_set_list (pbi, mem)
2341 struct propagate_block_info *pbi;
2346 /* We don't know how large a BLKmode store is, so we must not
2347 take them into consideration. */
2348 if (GET_MODE (mem) == BLKmode)
2351 for (i = pbi->mem_set_list; i ; i = XEXP (i, 1))
2353 rtx e = XEXP (i, 0);
2354 if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0)))
2356 if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e)))
2359 /* If we must store a copy of the mem, we can just modify
2360 the mode of the stored copy. */
2361 if (pbi->flags & PROP_AUTOINC)
2362 PUT_MODE (e, GET_MODE (mem));
2371 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN)
2374 /* Store a copy of mem, otherwise the address may be
2375 scrogged by find_auto_inc. */
2376 if (pbi->flags & PROP_AUTOINC)
2377 mem = shallow_copy_rtx (mem);
2379 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
2380 pbi->mem_set_list_len++;
2384 /* INSN references memory, possibly using autoincrement addressing modes.
2385 Find any entries on the mem_set_list that need to be invalidated due
2386 to an address change. */
2389 invalidate_mems_from_autoinc (pbi, insn)
2390 struct propagate_block_info *pbi;
2393 rtx note = REG_NOTES (insn);
2394 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
2395 if (REG_NOTE_KIND (note) == REG_INC)
2396 invalidate_mems_from_set (pbi, XEXP (note, 0));
2399 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2402 invalidate_mems_from_set (pbi, exp)
2403 struct propagate_block_info *pbi;
2406 rtx temp = pbi->mem_set_list;
2407 rtx prev = NULL_RTX;
2412 next = XEXP (temp, 1);
2413 if (reg_overlap_mentioned_p (exp, XEXP (temp, 0)))
2415 /* Splice this entry out of the list. */
2417 XEXP (prev, 1) = next;
2419 pbi->mem_set_list = next;
2420 free_EXPR_LIST_node (temp);
2421 pbi->mem_set_list_len--;
2429 /* Process the registers that are set within X. Their bits are set to
2430 1 in the regset DEAD, because they are dead prior to this insn.
2432 If INSN is nonzero, it is the insn being processed.
2434 FLAGS is the set of operations to perform. */
2437 mark_set_regs (pbi, x, insn)
2438 struct propagate_block_info *pbi;
2441 rtx cond = NULL_RTX;
2446 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2448 if (REG_NOTE_KIND (link) == REG_INC)
2449 mark_set_1 (pbi, SET, XEXP (link, 0),
2450 (GET_CODE (x) == COND_EXEC
2451 ? COND_EXEC_TEST (x) : NULL_RTX),
2455 switch (code = GET_CODE (x))
2459 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, pbi->flags);
2463 cond = COND_EXEC_TEST (x);
2464 x = COND_EXEC_CODE (x);
2471 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2473 rtx sub = XVECEXP (x, 0, i);
2474 switch (code = GET_CODE (sub))
2477 if (cond != NULL_RTX)
2480 cond = COND_EXEC_TEST (sub);
2481 sub = COND_EXEC_CODE (sub);
2482 if (GET_CODE (sub) != SET && GET_CODE (sub) != CLOBBER)
2488 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, pbi->flags);
2503 /* Process a single set, which appears in INSN. REG (which may not
2504 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2505 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2506 If the set is conditional (because it appear in a COND_EXEC), COND
2507 will be the condition. */
2510 mark_set_1 (pbi, code, reg, cond, insn, flags)
2511 struct propagate_block_info *pbi;
2513 rtx reg, cond, insn;
2516 int regno_first = -1, regno_last = -1;
2517 unsigned long not_dead = 0;
2520 /* Modifying just one hardware register of a multi-reg value or just a
2521 byte field of a register does not mean the value from before this insn
2522 is now dead. Of course, if it was dead after it's unused now. */
2524 switch (GET_CODE (reg))
2527 /* Some targets place small structures in registers for return values of
2528 functions. We have to detect this case specially here to get correct
2529 flow information. */
2530 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
2531 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
2532 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
2538 case STRICT_LOW_PART:
2539 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2541 reg = XEXP (reg, 0);
2542 while (GET_CODE (reg) == SUBREG
2543 || GET_CODE (reg) == ZERO_EXTRACT
2544 || GET_CODE (reg) == SIGN_EXTRACT
2545 || GET_CODE (reg) == STRICT_LOW_PART);
2546 if (GET_CODE (reg) == MEM)
2548 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
2552 regno_last = regno_first = REGNO (reg);
2553 if (regno_first < FIRST_PSEUDO_REGISTER)
2554 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
2558 if (GET_CODE (SUBREG_REG (reg)) == REG)
2560 enum machine_mode outer_mode = GET_MODE (reg);
2561 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
2563 /* Identify the range of registers affected. This is moderately
2564 tricky for hard registers. See alter_subreg. */
2566 regno_last = regno_first = REGNO (SUBREG_REG (reg));
2567 if (regno_first < FIRST_PSEUDO_REGISTER)
2569 regno_first += subreg_regno_offset (regno_first, inner_mode,
2572 regno_last = (regno_first
2573 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
2575 /* Since we've just adjusted the register number ranges, make
2576 sure REG matches. Otherwise some_was_live will be clear
2577 when it shouldn't have been, and we'll create incorrect
2578 REG_UNUSED notes. */
2579 reg = gen_rtx_REG (outer_mode, regno_first);
2583 /* If the number of words in the subreg is less than the number
2584 of words in the full register, we have a well-defined partial
2585 set. Otherwise the high bits are undefined.
2587 This is only really applicable to pseudos, since we just took
2588 care of multi-word hard registers. */
2589 if (((GET_MODE_SIZE (outer_mode)
2590 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
2591 < ((GET_MODE_SIZE (inner_mode)
2592 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
2593 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
2596 reg = SUBREG_REG (reg);
2600 reg = SUBREG_REG (reg);
2607 /* If this set is a MEM, then it kills any aliased writes.
2608 If this set is a REG, then it kills any MEMs which use the reg. */
2609 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
2611 if (GET_CODE (reg) == REG)
2612 invalidate_mems_from_set (pbi, reg);
2614 /* If the memory reference had embedded side effects (autoincrement
2615 address modes. Then we may need to kill some entries on the
2617 if (insn && GET_CODE (reg) == MEM)
2618 invalidate_mems_from_autoinc (pbi, insn);
2620 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
2621 /* ??? With more effort we could track conditional memory life. */
2623 /* There are no REG_INC notes for SP, so we can't assume we'll see
2624 everything that invalidates it. To be safe, don't eliminate any
2625 stores though SP; none of them should be redundant anyway. */
2626 && ! reg_mentioned_p (stack_pointer_rtx, reg))
2627 add_to_mem_set_list (pbi, canon_rtx (reg));
2630 if (GET_CODE (reg) == REG
2631 && ! (regno_first == FRAME_POINTER_REGNUM
2632 && (! reload_completed || frame_pointer_needed))
2633 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2634 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
2635 && (! reload_completed || frame_pointer_needed))
2637 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2638 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
2642 int some_was_live = 0, some_was_dead = 0;
2644 for (i = regno_first; i <= regno_last; ++i)
2646 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
2649 /* Order of the set operation matters here since both
2650 sets may be the same. */
2651 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
2652 if (cond != NULL_RTX
2653 && ! REGNO_REG_SET_P (pbi->local_set, i))
2654 SET_REGNO_REG_SET (pbi->cond_local_set, i);
2656 SET_REGNO_REG_SET (pbi->local_set, i);
2658 if (code != CLOBBER)
2659 SET_REGNO_REG_SET (pbi->new_set, i);
2661 some_was_live |= needed_regno;
2662 some_was_dead |= ! needed_regno;
2665 #ifdef HAVE_conditional_execution
2666 /* Consider conditional death in deciding that the register needs
2668 if (some_was_live && ! not_dead
2669 /* The stack pointer is never dead. Well, not strictly true,
2670 but it's very difficult to tell from here. Hopefully
2671 combine_stack_adjustments will fix up the most egregious
2673 && regno_first != STACK_POINTER_REGNUM)
2675 for (i = regno_first; i <= regno_last; ++i)
2676 if (! mark_regno_cond_dead (pbi, i, cond))
2677 not_dead |= ((unsigned long) 1) << (i - regno_first);
2681 /* Additional data to record if this is the final pass. */
2682 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
2683 | PROP_DEATH_NOTES | PROP_AUTOINC))
2686 int blocknum = pbi->bb->index;
2689 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2691 y = pbi->reg_next_use[regno_first];
2693 /* The next use is no longer next, since a store intervenes. */
2694 for (i = regno_first; i <= regno_last; ++i)
2695 pbi->reg_next_use[i] = 0;
2698 if (flags & PROP_REG_INFO)
2700 for (i = regno_first; i <= regno_last; ++i)
2702 /* Count (weighted) references, stores, etc. This counts a
2703 register twice if it is modified, but that is correct. */
2704 REG_N_SETS (i) += 1;
2705 REG_N_REFS (i) += 1;
2706 REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb);
2708 /* The insns where a reg is live are normally counted
2709 elsewhere, but we want the count to include the insn
2710 where the reg is set, and the normal counting mechanism
2711 would not count it. */
2712 REG_LIVE_LENGTH (i) += 1;
2715 /* If this is a hard reg, record this function uses the reg. */
2716 if (regno_first < FIRST_PSEUDO_REGISTER)
2718 for (i = regno_first; i <= regno_last; i++)
2719 regs_ever_live[i] = 1;
2723 /* Keep track of which basic blocks each reg appears in. */
2724 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
2725 REG_BASIC_BLOCK (regno_first) = blocknum;
2726 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
2727 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
2731 if (! some_was_dead)
2733 if (flags & PROP_LOG_LINKS)
2735 /* Make a logical link from the next following insn
2736 that uses this register, back to this insn.
2737 The following insns have already been processed.
2739 We don't build a LOG_LINK for hard registers containing
2740 in ASM_OPERANDs. If these registers get replaced,
2741 we might wind up changing the semantics of the insn,
2742 even if reload can make what appear to be valid
2743 assignments later. */
2744 if (y && (BLOCK_NUM (y) == blocknum)
2745 && (regno_first >= FIRST_PSEUDO_REGISTER
2746 || asm_noperands (PATTERN (y)) < 0))
2747 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
2752 else if (! some_was_live)
2754 if (flags & PROP_REG_INFO)
2755 REG_N_DEATHS (regno_first) += 1;
2757 if (flags & PROP_DEATH_NOTES)
2759 /* Note that dead stores have already been deleted
2760 when possible. If we get here, we have found a
2761 dead store that cannot be eliminated (because the
2762 same insn does something useful). Indicate this
2763 by marking the reg being set as dying here. */
2765 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2770 if (flags & PROP_DEATH_NOTES)
2772 /* This is a case where we have a multi-word hard register
2773 and some, but not all, of the words of the register are
2774 needed in subsequent insns. Write REG_UNUSED notes
2775 for those parts that were not needed. This case should
2778 for (i = regno_first; i <= regno_last; ++i)
2779 if (! REGNO_REG_SET_P (pbi->reg_live, i))
2781 = alloc_EXPR_LIST (REG_UNUSED,
2782 gen_rtx_REG (reg_raw_mode[i], i),
2788 /* Mark the register as being dead. */
2790 /* The stack pointer is never dead. Well, not strictly true,
2791 but it's very difficult to tell from here. Hopefully
2792 combine_stack_adjustments will fix up the most egregious
2794 && regno_first != STACK_POINTER_REGNUM)
2796 for (i = regno_first; i <= regno_last; ++i)
2797 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
2798 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
2801 else if (GET_CODE (reg) == REG)
2803 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2804 pbi->reg_next_use[regno_first] = 0;
2807 /* If this is the last pass and this is a SCRATCH, show it will be dying
2808 here and count it. */
2809 else if (GET_CODE (reg) == SCRATCH)
2811 if (flags & PROP_DEATH_NOTES)
2813 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2817 #ifdef HAVE_conditional_execution
2818 /* Mark REGNO conditionally dead.
2819 Return true if the register is now unconditionally dead. */
2822 mark_regno_cond_dead (pbi, regno, cond)
2823 struct propagate_block_info *pbi;
2827 /* If this is a store to a predicate register, the value of the
2828 predicate is changing, we don't know that the predicate as seen
2829 before is the same as that seen after. Flush all dependent
2830 conditions from reg_cond_dead. This will make all such
2831 conditionally live registers unconditionally live. */
2832 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
2833 flush_reg_cond_reg (pbi, regno);
2835 /* If this is an unconditional store, remove any conditional
2836 life that may have existed. */
2837 if (cond == NULL_RTX)
2838 splay_tree_remove (pbi->reg_cond_dead, regno);
2841 splay_tree_node node;
2842 struct reg_cond_life_info *rcli;
2845 /* Otherwise this is a conditional set. Record that fact.
2846 It may have been conditionally used, or there may be a
2847 subsequent set with a complimentary condition. */
2849 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
2852 /* The register was unconditionally live previously.
2853 Record the current condition as the condition under
2854 which it is dead. */
2855 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
2856 rcli->condition = cond;
2857 rcli->stores = cond;
2858 rcli->orig_condition = const0_rtx;
2859 splay_tree_insert (pbi->reg_cond_dead, regno,
2860 (splay_tree_value) rcli);
2862 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2864 /* Not unconditionally dead. */
2869 /* The register was conditionally live previously.
2870 Add the new condition to the old. */
2871 rcli = (struct reg_cond_life_info *) node->value;
2872 ncond = rcli->condition;
2873 ncond = ior_reg_cond (ncond, cond, 1);
2874 if (rcli->stores == const0_rtx)
2875 rcli->stores = cond;
2876 else if (rcli->stores != const1_rtx)
2877 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
2879 /* If the register is now unconditionally dead, remove the entry
2880 in the splay_tree. A register is unconditionally dead if the
2881 dead condition ncond is true. A register is also unconditionally
2882 dead if the sum of all conditional stores is an unconditional
2883 store (stores is true), and the dead condition is identically the
2884 same as the original dead condition initialized at the end of
2885 the block. This is a pointer compare, not an rtx_equal_p
2887 if (ncond == const1_rtx
2888 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
2889 splay_tree_remove (pbi->reg_cond_dead, regno);
2892 rcli->condition = ncond;
2894 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2896 /* Not unconditionally dead. */
2905 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2908 free_reg_cond_life_info (value)
2909 splay_tree_value value;
2911 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
2915 /* Helper function for flush_reg_cond_reg. */
2918 flush_reg_cond_reg_1 (node, data)
2919 splay_tree_node node;
2922 struct reg_cond_life_info *rcli;
2923 int *xdata = (int *) data;
2924 unsigned int regno = xdata[0];
2926 /* Don't need to search if last flushed value was farther on in
2927 the in-order traversal. */
2928 if (xdata[1] >= (int) node->key)
2931 /* Splice out portions of the expression that refer to regno. */
2932 rcli = (struct reg_cond_life_info *) node->value;
2933 rcli->condition = elim_reg_cond (rcli->condition, regno);
2934 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
2935 rcli->stores = elim_reg_cond (rcli->stores, regno);
2937 /* If the entire condition is now false, signal the node to be removed. */
2938 if (rcli->condition == const0_rtx)
2940 xdata[1] = node->key;
2943 else if (rcli->condition == const1_rtx)
2949 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2952 flush_reg_cond_reg (pbi, regno)
2953 struct propagate_block_info *pbi;
2960 while (splay_tree_foreach (pbi->reg_cond_dead,
2961 flush_reg_cond_reg_1, pair) == -1)
2962 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
2964 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
2967 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2968 For ior/and, the ADD flag determines whether we want to add the new
2969 condition X to the old one unconditionally. If it is zero, we will
2970 only return a new expression if X allows us to simplify part of
2971 OLD, otherwise we return NULL to the caller.
2972 If ADD is nonzero, we will return a new condition in all cases. The
2973 toplevel caller of one of these functions should always pass 1 for
2977 ior_reg_cond (old, x, add)
2983 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
2985 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
2986 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
2987 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2989 if (GET_CODE (x) == GET_CODE (old)
2990 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2994 return gen_rtx_IOR (0, old, x);
2997 switch (GET_CODE (old))
3000 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3001 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3002 if (op0 != NULL || op1 != NULL)
3004 if (op0 == const0_rtx)
3005 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3006 if (op1 == const0_rtx)
3007 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3008 if (op0 == const1_rtx || op1 == const1_rtx)
3011 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3012 else if (rtx_equal_p (x, op0))
3013 /* (x | A) | x ~ (x | A). */
3016 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3017 else if (rtx_equal_p (x, op1))
3018 /* (A | x) | x ~ (A | x). */
3020 return gen_rtx_IOR (0, op0, op1);
3024 return gen_rtx_IOR (0, old, x);
3027 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3028 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3029 if (op0 != NULL || op1 != NULL)
3031 if (op0 == const1_rtx)
3032 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3033 if (op1 == const1_rtx)
3034 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3035 if (op0 == const0_rtx || op1 == const0_rtx)
3038 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3039 else if (rtx_equal_p (x, op0))
3040 /* (x & A) | x ~ x. */
3043 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3044 else if (rtx_equal_p (x, op1))
3045 /* (A & x) | x ~ x. */
3047 return gen_rtx_AND (0, op0, op1);
3051 return gen_rtx_IOR (0, old, x);
3054 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3056 return not_reg_cond (op0);
3059 return gen_rtx_IOR (0, old, x);
3070 enum rtx_code x_code;
3072 if (x == const0_rtx)
3074 else if (x == const1_rtx)
3076 x_code = GET_CODE (x);
3079 if (GET_RTX_CLASS (x_code) == '<'
3080 && GET_CODE (XEXP (x, 0)) == REG)
3082 if (XEXP (x, 1) != const0_rtx)
3085 return gen_rtx_fmt_ee (reverse_condition (x_code),
3086 VOIDmode, XEXP (x, 0), const0_rtx);
3088 return gen_rtx_NOT (0, x);
3092 and_reg_cond (old, x, add)
3098 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
3100 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
3101 && GET_CODE (x) == reverse_condition (GET_CODE (old))
3102 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3104 if (GET_CODE (x) == GET_CODE (old)
3105 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3109 return gen_rtx_AND (0, old, x);
3112 switch (GET_CODE (old))
3115 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3116 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3117 if (op0 != NULL || op1 != NULL)
3119 if (op0 == const0_rtx)
3120 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3121 if (op1 == const0_rtx)
3122 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3123 if (op0 == const1_rtx || op1 == const1_rtx)
3126 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3127 else if (rtx_equal_p (x, op0))
3128 /* (x | A) & x ~ x. */
3131 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3132 else if (rtx_equal_p (x, op1))
3133 /* (A | x) & x ~ x. */
3135 return gen_rtx_IOR (0, op0, op1);
3139 return gen_rtx_AND (0, old, x);
3142 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3143 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3144 if (op0 != NULL || op1 != NULL)
3146 if (op0 == const1_rtx)
3147 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3148 if (op1 == const1_rtx)
3149 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3150 if (op0 == const0_rtx || op1 == const0_rtx)
3153 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3154 else if (rtx_equal_p (x, op0))
3155 /* (x & A) & x ~ (x & A). */
3158 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3159 else if (rtx_equal_p (x, op1))
3160 /* (A & x) & x ~ (A & x). */
3162 return gen_rtx_AND (0, op0, op1);
3166 return gen_rtx_AND (0, old, x);
3169 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3171 return not_reg_cond (op0);
3174 return gen_rtx_AND (0, old, x);
3181 /* Given a condition X, remove references to reg REGNO and return the
3182 new condition. The removal will be done so that all conditions
3183 involving REGNO are considered to evaluate to false. This function
3184 is used when the value of REGNO changes. */
3187 elim_reg_cond (x, regno)
3193 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
3195 if (REGNO (XEXP (x, 0)) == regno)
3200 switch (GET_CODE (x))
3203 op0 = elim_reg_cond (XEXP (x, 0), regno);
3204 op1 = elim_reg_cond (XEXP (x, 1), regno);
3205 if (op0 == const0_rtx || op1 == const0_rtx)
3207 if (op0 == const1_rtx)
3209 if (op1 == const1_rtx)
3211 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3213 return gen_rtx_AND (0, op0, op1);
3216 op0 = elim_reg_cond (XEXP (x, 0), regno);
3217 op1 = elim_reg_cond (XEXP (x, 1), regno);
3218 if (op0 == const1_rtx || op1 == const1_rtx)
3220 if (op0 == const0_rtx)
3222 if (op1 == const0_rtx)
3224 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3226 return gen_rtx_IOR (0, op0, op1);
3229 op0 = elim_reg_cond (XEXP (x, 0), regno);
3230 if (op0 == const0_rtx)
3232 if (op0 == const1_rtx)
3234 if (op0 != XEXP (x, 0))
3235 return not_reg_cond (op0);
3242 #endif /* HAVE_conditional_execution */
3246 /* Try to substitute the auto-inc expression INC as the address inside
3247 MEM which occurs in INSN. Currently, the address of MEM is an expression
3248 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3249 that has a single set whose source is a PLUS of INCR_REG and something
3253 attempt_auto_inc (pbi, inc, insn, mem, incr, incr_reg)
3254 struct propagate_block_info *pbi;
3255 rtx inc, insn, mem, incr, incr_reg;
3257 int regno = REGNO (incr_reg);
3258 rtx set = single_set (incr);
3259 rtx q = SET_DEST (set);
3260 rtx y = SET_SRC (set);
3261 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
3263 /* Make sure this reg appears only once in this insn. */
3264 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
3267 if (dead_or_set_p (incr, incr_reg)
3268 /* Mustn't autoinc an eliminable register. */
3269 && (regno >= FIRST_PSEUDO_REGISTER
3270 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
3272 /* This is the simple case. Try to make the auto-inc. If
3273 we can't, we are done. Otherwise, we will do any
3274 needed updates below. */
3275 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
3278 else if (GET_CODE (q) == REG
3279 /* PREV_INSN used here to check the semi-open interval
3281 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
3282 /* We must also check for sets of q as q may be
3283 a call clobbered hard register and there may
3284 be a call between PREV_INSN (insn) and incr. */
3285 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
3287 /* We have *p followed sometime later by q = p+size.
3288 Both p and q must be live afterward,
3289 and q is not used between INSN and its assignment.
3290 Change it to q = p, ...*q..., q = q+size.
3291 Then fall into the usual case. */
3295 emit_move_insn (q, incr_reg);
3296 insns = get_insns ();
3299 /* If we can't make the auto-inc, or can't make the
3300 replacement into Y, exit. There's no point in making
3301 the change below if we can't do the auto-inc and doing
3302 so is not correct in the pre-inc case. */
3305 validate_change (insn, &XEXP (mem, 0), inc, 1);
3306 validate_change (incr, &XEXP (y, opnum), q, 1);
3307 if (! apply_change_group ())
3310 /* We now know we'll be doing this change, so emit the
3311 new insn(s) and do the updates. */
3312 emit_insns_before (insns, insn);
3314 if (pbi->bb->head == insn)
3315 pbi->bb->head = insns;
3317 /* INCR will become a NOTE and INSN won't contain a
3318 use of INCR_REG. If a use of INCR_REG was just placed in
3319 the insn before INSN, make that the next use.
3320 Otherwise, invalidate it. */
3321 if (GET_CODE (PREV_INSN (insn)) == INSN
3322 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
3323 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
3324 pbi->reg_next_use[regno] = PREV_INSN (insn);
3326 pbi->reg_next_use[regno] = 0;
3331 /* REGNO is now used in INCR which is below INSN, but
3332 it previously wasn't live here. If we don't mark
3333 it as live, we'll put a REG_DEAD note for it
3334 on this insn, which is incorrect. */
3335 SET_REGNO_REG_SET (pbi->reg_live, regno);
3337 /* If there are any calls between INSN and INCR, show
3338 that REGNO now crosses them. */
3339 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
3340 if (GET_CODE (temp) == CALL_INSN)
3341 REG_N_CALLS_CROSSED (regno)++;
3343 /* Invalidate alias info for Q since we just changed its value. */
3344 clear_reg_alias_info (q);
3349 /* If we haven't returned, it means we were able to make the
3350 auto-inc, so update the status. First, record that this insn
3351 has an implicit side effect. */
3353 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
3355 /* Modify the old increment-insn to simply copy
3356 the already-incremented value of our register. */
3357 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
3360 /* If that makes it a no-op (copying the register into itself) delete
3361 it so it won't appear to be a "use" and a "set" of this
3363 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
3365 /* If the original source was dead, it's dead now. */
3368 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
3370 remove_note (incr, note);
3371 if (XEXP (note, 0) != incr_reg)
3372 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
3375 PUT_CODE (incr, NOTE);
3376 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
3377 NOTE_SOURCE_FILE (incr) = 0;
3380 if (regno >= FIRST_PSEUDO_REGISTER)
3382 /* Count an extra reference to the reg. When a reg is
3383 incremented, spilling it is worse, so we want to make
3384 that less likely. */
3385 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3387 /* Count the increment as a setting of the register,
3388 even though it isn't a SET in rtl. */
3389 REG_N_SETS (regno)++;
3393 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3397 find_auto_inc (pbi, x, insn)
3398 struct propagate_block_info *pbi;
3402 rtx addr = XEXP (x, 0);
3403 HOST_WIDE_INT offset = 0;
3404 rtx set, y, incr, inc_val;
3406 int size = GET_MODE_SIZE (GET_MODE (x));
3408 if (GET_CODE (insn) == JUMP_INSN)
3411 /* Here we detect use of an index register which might be good for
3412 postincrement, postdecrement, preincrement, or predecrement. */
3414 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
3415 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
3417 if (GET_CODE (addr) != REG)
3420 regno = REGNO (addr);
3422 /* Is the next use an increment that might make auto-increment? */
3423 incr = pbi->reg_next_use[regno];
3424 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
3426 set = single_set (incr);
3427 if (set == 0 || GET_CODE (set) != SET)
3431 if (GET_CODE (y) != PLUS)
3434 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
3435 inc_val = XEXP (y, 1);
3436 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
3437 inc_val = XEXP (y, 0);
3441 if (GET_CODE (inc_val) == CONST_INT)
3443 if (HAVE_POST_INCREMENT
3444 && (INTVAL (inc_val) == size && offset == 0))
3445 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
3447 else if (HAVE_POST_DECREMENT
3448 && (INTVAL (inc_val) == -size && offset == 0))
3449 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
3451 else if (HAVE_PRE_INCREMENT
3452 && (INTVAL (inc_val) == size && offset == size))
3453 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
3455 else if (HAVE_PRE_DECREMENT
3456 && (INTVAL (inc_val) == -size && offset == -size))
3457 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
3459 else if (HAVE_POST_MODIFY_DISP && offset == 0)
3460 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3461 gen_rtx_PLUS (Pmode,
3464 insn, x, incr, addr);
3466 else if (GET_CODE (inc_val) == REG
3467 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
3471 if (HAVE_POST_MODIFY_REG && offset == 0)
3472 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3473 gen_rtx_PLUS (Pmode,
3476 insn, x, incr, addr);
3480 #endif /* AUTO_INC_DEC */
3483 mark_used_reg (pbi, reg, cond, insn)
3484 struct propagate_block_info *pbi;
3486 rtx cond ATTRIBUTE_UNUSED;
3489 unsigned int regno_first, regno_last, i;
3490 int some_was_live, some_was_dead, some_not_set;
3492 regno_last = regno_first = REGNO (reg);
3493 if (regno_first < FIRST_PSEUDO_REGISTER)
3494 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
3496 /* Find out if any of this register is live after this instruction. */
3497 some_was_live = some_was_dead = 0;
3498 for (i = regno_first; i <= regno_last; ++i)
3500 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
3501 some_was_live |= needed_regno;
3502 some_was_dead |= ! needed_regno;
3505 /* Find out if any of the register was set this insn. */
3507 for (i = regno_first; i <= regno_last; ++i)
3508 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
3510 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3512 /* Record where each reg is used, so when the reg is set we know
3513 the next insn that uses it. */
3514 pbi->reg_next_use[regno_first] = insn;
3517 if (pbi->flags & PROP_REG_INFO)
3519 if (regno_first < FIRST_PSEUDO_REGISTER)
3521 /* If this is a register we are going to try to eliminate,
3522 don't mark it live here. If we are successful in
3523 eliminating it, it need not be live unless it is used for
3524 pseudos, in which case it will have been set live when it
3525 was allocated to the pseudos. If the register will not
3526 be eliminated, reload will set it live at that point.
3528 Otherwise, record that this function uses this register. */
3529 /* ??? The PPC backend tries to "eliminate" on the pic
3530 register to itself. This should be fixed. In the mean
3531 time, hack around it. */
3533 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
3534 && (regno_first == FRAME_POINTER_REGNUM
3535 || regno_first == ARG_POINTER_REGNUM)))
3536 for (i = regno_first; i <= regno_last; ++i)
3537 regs_ever_live[i] = 1;
3541 /* Keep track of which basic block each reg appears in. */
3543 int blocknum = pbi->bb->index;
3544 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
3545 REG_BASIC_BLOCK (regno_first) = blocknum;
3546 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
3547 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
3549 /* Count (weighted) number of uses of each reg. */
3550 REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb);
3551 REG_N_REFS (regno_first)++;
3555 /* Record and count the insns in which a reg dies. If it is used in
3556 this insn and was dead below the insn then it dies in this insn.
3557 If it was set in this insn, we do not make a REG_DEAD note;
3558 likewise if we already made such a note. */
3559 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
3563 /* Check for the case where the register dying partially
3564 overlaps the register set by this insn. */
3565 if (regno_first != regno_last)
3566 for (i = regno_first; i <= regno_last; ++i)
3567 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
3569 /* If none of the words in X is needed, make a REG_DEAD note.
3570 Otherwise, we must make partial REG_DEAD notes. */
3571 if (! some_was_live)
3573 if ((pbi->flags & PROP_DEATH_NOTES)
3574 && ! find_regno_note (insn, REG_DEAD, regno_first))
3576 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
3578 if (pbi->flags & PROP_REG_INFO)
3579 REG_N_DEATHS (regno_first)++;
3583 /* Don't make a REG_DEAD note for a part of a register
3584 that is set in the insn. */
3585 for (i = regno_first; i <= regno_last; ++i)
3586 if (! REGNO_REG_SET_P (pbi->reg_live, i)
3587 && ! dead_or_set_regno_p (insn, i))
3589 = alloc_EXPR_LIST (REG_DEAD,
3590 gen_rtx_REG (reg_raw_mode[i], i),
3595 /* Mark the register as being live. */
3596 for (i = regno_first; i <= regno_last; ++i)
3598 SET_REGNO_REG_SET (pbi->reg_live, i);
3600 #ifdef HAVE_conditional_execution
3601 /* If this is a conditional use, record that fact. If it is later
3602 conditionally set, we'll know to kill the register. */
3603 if (cond != NULL_RTX)
3605 splay_tree_node node;
3606 struct reg_cond_life_info *rcli;
3611 node = splay_tree_lookup (pbi->reg_cond_dead, i);
3614 /* The register was unconditionally live previously.
3615 No need to do anything. */
3619 /* The register was conditionally live previously.
3620 Subtract the new life cond from the old death cond. */
3621 rcli = (struct reg_cond_life_info *) node->value;
3622 ncond = rcli->condition;
3623 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
3625 /* If the register is now unconditionally live,
3626 remove the entry in the splay_tree. */
3627 if (ncond == const0_rtx)
3628 splay_tree_remove (pbi->reg_cond_dead, i);
3631 rcli->condition = ncond;
3632 SET_REGNO_REG_SET (pbi->reg_cond_reg,
3633 REGNO (XEXP (cond, 0)));
3639 /* The register was not previously live at all. Record
3640 the condition under which it is still dead. */
3641 rcli = (struct reg_cond_life_info *) xmalloc (sizeof (*rcli));
3642 rcli->condition = not_reg_cond (cond);
3643 rcli->stores = const0_rtx;
3644 rcli->orig_condition = const0_rtx;
3645 splay_tree_insert (pbi->reg_cond_dead, i,
3646 (splay_tree_value) rcli);
3648 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
3651 else if (some_was_live)
3653 /* The register may have been conditionally live previously, but
3654 is now unconditionally live. Remove it from the conditionally
3655 dead list, so that a conditional set won't cause us to think
3657 splay_tree_remove (pbi->reg_cond_dead, i);
3663 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3664 This is done assuming the registers needed from X are those that
3665 have 1-bits in PBI->REG_LIVE.
3667 INSN is the containing instruction. If INSN is dead, this function
3671 mark_used_regs (pbi, x, cond, insn)
3672 struct propagate_block_info *pbi;
3677 int flags = pbi->flags;
3682 code = GET_CODE (x);
3703 /* If we are clobbering a MEM, mark any registers inside the address
3705 if (GET_CODE (XEXP (x, 0)) == MEM)
3706 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
3710 /* Don't bother watching stores to mems if this is not the
3711 final pass. We'll not be deleting dead stores this round. */
3712 if (optimize && (flags & PROP_SCAN_DEAD_CODE))
3714 /* Invalidate the data for the last MEM stored, but only if MEM is
3715 something that can be stored into. */
3716 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3717 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3718 /* Needn't clear the memory set list. */
3722 rtx temp = pbi->mem_set_list;
3723 rtx prev = NULL_RTX;
3728 next = XEXP (temp, 1);
3729 if (anti_dependence (XEXP (temp, 0), x))
3731 /* Splice temp out of the list. */
3733 XEXP (prev, 1) = next;
3735 pbi->mem_set_list = next;
3736 free_EXPR_LIST_node (temp);
3737 pbi->mem_set_list_len--;
3745 /* If the memory reference had embedded side effects (autoincrement
3746 address modes. Then we may need to kill some entries on the
3749 invalidate_mems_from_autoinc (pbi, insn);
3753 if (flags & PROP_AUTOINC)
3754 find_auto_inc (pbi, x, insn);
3759 #ifdef CLASS_CANNOT_CHANGE_MODE
3760 if (GET_CODE (SUBREG_REG (x)) == REG
3761 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
3762 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (x),
3763 GET_MODE (SUBREG_REG (x))))
3764 REG_CHANGES_MODE (REGNO (SUBREG_REG (x))) = 1;
3767 /* While we're here, optimize this case. */
3769 if (GET_CODE (x) != REG)
3774 /* See a register other than being set => mark it as needed. */
3775 mark_used_reg (pbi, x, cond, insn);
3780 rtx testreg = SET_DEST (x);
3783 /* If storing into MEM, don't show it as being used. But do
3784 show the address as being used. */
3785 if (GET_CODE (testreg) == MEM)
3788 if (flags & PROP_AUTOINC)
3789 find_auto_inc (pbi, testreg, insn);
3791 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
3792 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3796 /* Storing in STRICT_LOW_PART is like storing in a reg
3797 in that this SET might be dead, so ignore it in TESTREG.
3798 but in some other ways it is like using the reg.
3800 Storing in a SUBREG or a bit field is like storing the entire
3801 register in that if the register's value is not used
3802 then this SET is not needed. */
3803 while (GET_CODE (testreg) == STRICT_LOW_PART
3804 || GET_CODE (testreg) == ZERO_EXTRACT
3805 || GET_CODE (testreg) == SIGN_EXTRACT
3806 || GET_CODE (testreg) == SUBREG)
3808 #ifdef CLASS_CANNOT_CHANGE_MODE
3809 if (GET_CODE (testreg) == SUBREG
3810 && GET_CODE (SUBREG_REG (testreg)) == REG
3811 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
3812 && CLASS_CANNOT_CHANGE_MODE_P (GET_MODE (SUBREG_REG (testreg)),
3813 GET_MODE (testreg)))
3814 REG_CHANGES_MODE (REGNO (SUBREG_REG (testreg))) = 1;
3817 /* Modifying a single register in an alternate mode
3818 does not use any of the old value. But these other
3819 ways of storing in a register do use the old value. */
3820 if (GET_CODE (testreg) == SUBREG
3821 && !((REG_BYTES (SUBREG_REG (testreg))
3822 + UNITS_PER_WORD - 1) / UNITS_PER_WORD
3823 > (REG_BYTES (testreg)
3824 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
3829 testreg = XEXP (testreg, 0);
3832 /* If this is a store into a register or group of registers,
3833 recursively scan the value being stored. */
3835 if ((GET_CODE (testreg) == PARALLEL
3836 && GET_MODE (testreg) == BLKmode)
3837 || (GET_CODE (testreg) == REG
3838 && (regno = REGNO (testreg),
3839 ! (regno == FRAME_POINTER_REGNUM
3840 && (! reload_completed || frame_pointer_needed)))
3841 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3842 && ! (regno == HARD_FRAME_POINTER_REGNUM
3843 && (! reload_completed || frame_pointer_needed))
3845 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3846 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
3851 mark_used_regs (pbi, SET_DEST (x), cond, insn);
3852 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3859 case UNSPEC_VOLATILE:
3863 /* Traditional and volatile asm instructions must be considered to use
3864 and clobber all hard registers, all pseudo-registers and all of
3865 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3867 Consider for instance a volatile asm that changes the fpu rounding
3868 mode. An insn should not be moved across this even if it only uses
3869 pseudo-regs because it might give an incorrectly rounded result.
3871 ?!? Unfortunately, marking all hard registers as live causes massive
3872 problems for the register allocator and marking all pseudos as live
3873 creates mountains of uninitialized variable warnings.
3875 So for now, just clear the memory set list and mark any regs
3876 we can find in ASM_OPERANDS as used. */
3877 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
3879 free_EXPR_LIST_list (&pbi->mem_set_list);
3880 pbi->mem_set_list_len = 0;
3883 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3884 We can not just fall through here since then we would be confused
3885 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3886 traditional asms unlike their normal usage. */
3887 if (code == ASM_OPERANDS)
3891 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
3892 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
3898 if (cond != NULL_RTX)
3901 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
3903 cond = COND_EXEC_TEST (x);
3904 x = COND_EXEC_CODE (x);
3908 /* We _do_not_ want to scan operands of phi nodes. Operands of
3909 a phi function are evaluated only when control reaches this
3910 block along a particular edge. Therefore, regs that appear
3911 as arguments to phi should not be added to the global live at
3919 /* Recursively scan the operands of this expression. */
3922 const char * const fmt = GET_RTX_FORMAT (code);
3925 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3929 /* Tail recursive case: save a function call level. */
3935 mark_used_regs (pbi, XEXP (x, i), cond, insn);
3937 else if (fmt[i] == 'E')
3940 for (j = 0; j < XVECLEN (x, i); j++)
3941 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
3950 try_pre_increment_1 (pbi, insn)
3951 struct propagate_block_info *pbi;
3954 /* Find the next use of this reg. If in same basic block,
3955 make it do pre-increment or pre-decrement if appropriate. */
3956 rtx x = single_set (insn);
3957 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
3958 * INTVAL (XEXP (SET_SRC (x), 1)));
3959 int regno = REGNO (SET_DEST (x));
3960 rtx y = pbi->reg_next_use[regno];
3962 && SET_DEST (x) != stack_pointer_rtx
3963 && BLOCK_NUM (y) == BLOCK_NUM (insn)
3964 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3965 mode would be better. */
3966 && ! dead_or_set_p (y, SET_DEST (x))
3967 && try_pre_increment (y, SET_DEST (x), amount))
3969 /* We have found a suitable auto-increment and already changed
3970 insn Y to do it. So flush this increment instruction. */
3971 propagate_block_delete_insn (insn);
3973 /* Count a reference to this reg for the increment insn we are
3974 deleting. When a reg is incremented, spilling it is worse,
3975 so we want to make that less likely. */
3976 if (regno >= FIRST_PSEUDO_REGISTER)
3978 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3979 REG_N_SETS (regno)++;
3982 /* Flush any remembered memories depending on the value of
3983 the incremented register. */
3984 invalidate_mems_from_set (pbi, SET_DEST (x));
3991 /* Try to change INSN so that it does pre-increment or pre-decrement
3992 addressing on register REG in order to add AMOUNT to REG.
3993 AMOUNT is negative for pre-decrement.
3994 Returns 1 if the change could be made.
3995 This checks all about the validity of the result of modifying INSN. */
3998 try_pre_increment (insn, reg, amount)
4000 HOST_WIDE_INT amount;
4004 /* Nonzero if we can try to make a pre-increment or pre-decrement.
4005 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
4007 /* Nonzero if we can try to make a post-increment or post-decrement.
4008 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
4009 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
4010 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
4013 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
4016 /* From the sign of increment, see which possibilities are conceivable
4017 on this target machine. */
4018 if (HAVE_PRE_INCREMENT && amount > 0)
4020 if (HAVE_POST_INCREMENT && amount > 0)
4023 if (HAVE_PRE_DECREMENT && amount < 0)
4025 if (HAVE_POST_DECREMENT && amount < 0)
4028 if (! (pre_ok || post_ok))
4031 /* It is not safe to add a side effect to a jump insn
4032 because if the incremented register is spilled and must be reloaded
4033 there would be no way to store the incremented value back in memory. */
4035 if (GET_CODE (insn) == JUMP_INSN)
4040 use = find_use_as_address (PATTERN (insn), reg, 0);
4041 if (post_ok && (use == 0 || use == (rtx) (size_t) 1))
4043 use = find_use_as_address (PATTERN (insn), reg, -amount);
4047 if (use == 0 || use == (rtx) (size_t) 1)
4050 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
4053 /* See if this combination of instruction and addressing mode exists. */
4054 if (! validate_change (insn, &XEXP (use, 0),
4055 gen_rtx_fmt_e (amount > 0
4056 ? (do_post ? POST_INC : PRE_INC)
4057 : (do_post ? POST_DEC : PRE_DEC),
4061 /* Record that this insn now has an implicit side effect on X. */
4062 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
4066 #endif /* AUTO_INC_DEC */
4068 /* Find the place in the rtx X where REG is used as a memory address.
4069 Return the MEM rtx that so uses it.
4070 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4071 (plus REG (const_int PLUSCONST)).
4073 If such an address does not appear, return 0.
4074 If REG appears more than once, or is used other than in such an address,
4078 find_use_as_address (x, reg, plusconst)
4081 HOST_WIDE_INT plusconst;
4083 enum rtx_code code = GET_CODE (x);
4084 const char * const fmt = GET_RTX_FORMAT (code);
4089 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
4092 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
4093 && XEXP (XEXP (x, 0), 0) == reg
4094 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
4095 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
4098 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
4100 /* If REG occurs inside a MEM used in a bit-field reference,
4101 that is unacceptable. */
4102 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
4103 return (rtx) (size_t) 1;
4107 return (rtx) (size_t) 1;
4109 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4113 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
4117 return (rtx) (size_t) 1;
4119 else if (fmt[i] == 'E')
4122 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4124 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
4128 return (rtx) (size_t) 1;
4136 /* Write information about registers and basic blocks into FILE.
4137 This is part of making a debugging dump. */
4140 dump_regset (r, outf)
4147 fputs (" (nil)", outf);
4151 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
4153 fprintf (outf, " %d", i);
4154 if (i < FIRST_PSEUDO_REGISTER)
4155 fprintf (outf, " [%s]",
4160 /* Print a human-reaable representation of R on the standard error
4161 stream. This function is designed to be used from within the
4168 dump_regset (r, stderr);
4169 putc ('\n', stderr);
4172 /* Recompute register set/reference counts immediately prior to register
4175 This avoids problems with set/reference counts changing to/from values
4176 which have special meanings to the register allocators.
4178 Additionally, the reference counts are the primary component used by the
4179 register allocators to prioritize pseudos for allocation to hard regs.
4180 More accurate reference counts generally lead to better register allocation.
4182 F is the first insn to be scanned.
4184 LOOP_STEP denotes how much loop_depth should be incremented per
4185 loop nesting level in order to increase the ref count more for
4186 references in a loop.
4188 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4189 possibly other information which is used by the register allocators. */
4192 recompute_reg_usage (f, loop_step)
4193 rtx f ATTRIBUTE_UNUSED;
4194 int loop_step ATTRIBUTE_UNUSED;
4196 allocate_reg_life_data ();
4197 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
4200 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4201 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4202 of the number of registers that died. */
4205 count_or_remove_death_notes (blocks, kill)
4211 for (i = n_basic_blocks - 1; i >= 0; --i)
4216 if (blocks && ! TEST_BIT (blocks, i))
4219 bb = BASIC_BLOCK (i);
4221 for (insn = bb->head;; insn = NEXT_INSN (insn))
4225 rtx *pprev = ®_NOTES (insn);
4230 switch (REG_NOTE_KIND (link))
4233 if (GET_CODE (XEXP (link, 0)) == REG)
4235 rtx reg = XEXP (link, 0);
4238 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
4241 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
4249 rtx next = XEXP (link, 1);
4250 free_EXPR_LIST_node (link);
4251 *pprev = link = next;
4257 pprev = &XEXP (link, 1);
4264 if (insn == bb->end)
4271 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4272 if blocks is NULL. */
4275 clear_log_links (blocks)
4283 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4285 free_INSN_LIST_list (&LOG_LINKS (insn));
4288 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4290 basic_block bb = BASIC_BLOCK (i);
4292 for (insn = bb->head; insn != NEXT_INSN (bb->end);
4293 insn = NEXT_INSN (insn))
4295 free_INSN_LIST_list (&LOG_LINKS (insn));
4299 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4300 correspond to the hard registers, if any, set in that map. This
4301 could be done far more efficiently by having all sorts of special-cases
4302 with moving single words, but probably isn't worth the trouble. */
4305 reg_set_to_hard_reg_set (to, from)
4311 EXECUTE_IF_SET_IN_BITMAP
4314 if (i >= FIRST_PSEUDO_REGISTER)
4316 SET_HARD_REG_BIT (*to, i);