1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 /* This file contains the data flow analysis pass of the compiler. It
23 computes data flow information which tells combine_instructions
24 which insns to consider combining and controls register allocation.
26 Additional data flow information that is too bulky to record is
27 generated during the analysis, and is used at that time to create
28 autoincrement and autodecrement addressing.
30 The first step is dividing the function into basic blocks.
31 find_basic_blocks does this. Then life_analysis determines
32 where each register is live and where it is dead.
34 ** find_basic_blocks **
36 find_basic_blocks divides the current function's rtl into basic
37 blocks and constructs the CFG. The blocks are recorded in the
38 basic_block_info array; the CFG exists in the edge structures
39 referenced by the blocks.
41 find_basic_blocks also finds any unreachable loops and deletes them.
45 life_analysis is called immediately after find_basic_blocks.
46 It uses the basic block information to determine where each
47 hard or pseudo register is live.
49 ** live-register info **
51 The information about where each register is live is in two parts:
52 the REG_NOTES of insns, and the vector basic_block->global_live_at_start.
54 basic_block->global_live_at_start has an element for each basic
55 block, and the element is a bit-vector with a bit for each hard or
56 pseudo register. The bit is 1 if the register is live at the
57 beginning of the basic block.
59 Two types of elements can be added to an insn's REG_NOTES.
60 A REG_DEAD note is added to an insn's REG_NOTES for any register
61 that meets both of two conditions: The value in the register is not
62 needed in subsequent insns and the insn does not replace the value in
63 the register (in the case of multi-word hard registers, the value in
64 each register must be replaced by the insn to avoid a REG_DEAD note).
66 In the vast majority of cases, an object in a REG_DEAD note will be
67 used somewhere in the insn. The (rare) exception to this is if an
68 insn uses a multi-word hard register and only some of the registers are
69 needed in subsequent insns. In that case, REG_DEAD notes will be
70 provided for those hard registers that are not subsequently needed.
71 Partial REG_DEAD notes of this type do not occur when an insn sets
72 only some of the hard registers used in such a multi-word operand;
73 omitting REG_DEAD notes for objects stored in an insn is optional and
74 the desire to do so does not justify the complexity of the partial
77 REG_UNUSED notes are added for each register that is set by the insn
78 but is unused subsequently (if every register set by the insn is unused
79 and the insn does not reference memory or have some other side-effect,
80 the insn is deleted instead). If only part of a multi-word hard
81 register is used in a subsequent insn, REG_UNUSED notes are made for
82 the parts that will not be used.
84 To determine which registers are live after any insn, one can
85 start from the beginning of the basic block and scan insns, noting
86 which registers are set by each insn and which die there.
88 ** Other actions of life_analysis **
90 life_analysis sets up the LOG_LINKS fields of insns because the
91 information needed to do so is readily available.
93 life_analysis deletes insns whose only effect is to store a value
96 life_analysis notices cases where a reference to a register as
97 a memory address can be combined with a preceding or following
98 incrementation or decrementation of the register. The separate
99 instruction to increment or decrement is deleted and the address
100 is changed to a POST_INC or similar rtx.
102 Each time an incrementing or decrementing address is created,
103 a REG_INC element is added to the insn's REG_NOTES list.
105 life_analysis fills in certain vectors containing information about
106 register usage: REG_N_REFS, REG_N_DEATHS, REG_N_SETS, REG_LIVE_LENGTH,
107 REG_N_CALLS_CROSSED and REG_BASIC_BLOCK.
109 life_analysis sets current_function_sp_is_unchanging if the function
110 doesn't modify the stack pointer. */
114 Split out from life_analysis:
115 - local property discovery (bb->local_live, bb->local_set)
116 - global property computation
118 - pre/post modify transformation
123 #include "coretypes.h"
128 #include "hard-reg-set.h"
129 #include "basic-block.h"
130 #include "insn-config.h"
134 #include "function.h"
142 #include "splay-tree.h"
144 #ifndef HAVE_epilogue
145 #define HAVE_epilogue 0
147 #ifndef HAVE_prologue
148 #define HAVE_prologue 0
150 #ifndef HAVE_sibcall_epilogue
151 #define HAVE_sibcall_epilogue 0
154 #ifndef EPILOGUE_USES
155 #define EPILOGUE_USES(REGNO) 0
158 #define EH_USES(REGNO) 0
161 #ifdef HAVE_conditional_execution
162 #ifndef REVERSE_CONDEXEC_PREDICATES_P
163 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) \
164 (GET_CODE ((x)) == reversed_comparison_code ((y), NULL))
168 /* Nonzero if the second flow pass has completed. */
171 /* Maximum register number used in this function, plus one. */
175 /* Indexed by n, giving various register information */
177 varray_type reg_n_info;
179 /* Size of a regset for the current function,
180 in (1) bytes and (2) elements. */
185 /* Regset of regs live when calls to `setjmp'-like functions happen. */
186 /* ??? Does this exist only for the setjmp-clobbered warning message? */
188 regset regs_live_at_setjmp;
190 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
191 that have to go in the same hard reg.
192 The first two regs in the list are a pair, and the next two
193 are another pair, etc. */
196 /* Set of registers that may be eliminable. These are handled specially
197 in updating regs_ever_live. */
199 static HARD_REG_SET elim_reg_set;
201 /* Holds information for tracking conditional register life information. */
202 struct reg_cond_life_info
204 /* A boolean expression of conditions under which a register is dead. */
206 /* Conditions under which a register is dead at the basic block end. */
209 /* A boolean expression of conditions under which a register has been
213 /* ??? Could store mask of bytes that are dead, so that we could finally
214 track lifetimes of multi-word registers accessed via subregs. */
217 /* For use in communicating between propagate_block and its subroutines.
218 Holds all information needed to compute life and def-use information. */
220 struct propagate_block_info
222 /* The basic block we're considering. */
225 /* Bit N is set if register N is conditionally or unconditionally live. */
228 /* Bit N is set if register N is set this insn. */
231 /* Element N is the next insn that uses (hard or pseudo) register N
232 within the current basic block; or zero, if there is no such insn. */
235 /* Contains a list of all the MEMs we are tracking for dead store
239 /* If non-null, record the set of registers set unconditionally in the
243 /* If non-null, record the set of registers set conditionally in the
245 regset cond_local_set;
247 #ifdef HAVE_conditional_execution
248 /* Indexed by register number, holds a reg_cond_life_info for each
249 register that is not unconditionally live or dead. */
250 splay_tree reg_cond_dead;
252 /* Bit N is set if register N is in an expression in reg_cond_dead. */
256 /* The length of mem_set_list. */
257 int mem_set_list_len;
259 /* Nonzero if the value of CC0 is live. */
262 /* Flags controlling the set of information propagate_block collects. */
264 /* Index of instruction being processed. */
268 /* Number of dead insns removed. */
271 /* When PROP_REG_INFO set, array contains pbi->insn_num of instruction
272 where given register died. When the register is marked alive, we use the
273 information to compute amount of instructions life range cross.
274 (remember, we are walking backward). This can be computed as current
275 pbi->insn_num - reg_deaths[regno].
276 At the end of processing each basic block, the remaining live registers
277 are inspected and liferanges are increased same way so liverange of global
278 registers are computed correctly.
280 The array is maintained clear for dead registers, so it can be safely reused
281 for next basic block without expensive memset of the whole array after
282 reseting pbi->insn_num to 0. */
284 static int *reg_deaths;
286 /* Maximum length of pbi->mem_set_list before we start dropping
287 new elements on the floor. */
288 #define MAX_MEM_SET_LIST_LEN 100
290 /* Forward declarations */
291 static int verify_wide_reg_1 (rtx *, void *);
292 static void verify_wide_reg (int, basic_block);
293 static void verify_local_live_at_start (regset, basic_block);
294 static void notice_stack_pointer_modification_1 (rtx, rtx, void *);
295 static void notice_stack_pointer_modification (void);
296 static void mark_reg (rtx, void *);
297 static void mark_regs_live_at_end (regset);
298 static void calculate_global_regs_live (sbitmap, sbitmap, int);
299 static void propagate_block_delete_insn (rtx);
300 static rtx propagate_block_delete_libcall (rtx, rtx);
301 static int insn_dead_p (struct propagate_block_info *, rtx, int, rtx);
302 static int libcall_dead_p (struct propagate_block_info *, rtx, rtx);
303 static void mark_set_regs (struct propagate_block_info *, rtx, rtx);
304 static void mark_set_1 (struct propagate_block_info *, enum rtx_code, rtx,
306 static int find_regno_partial (rtx *, void *);
308 #ifdef HAVE_conditional_execution
309 static int mark_regno_cond_dead (struct propagate_block_info *, int, rtx);
310 static void free_reg_cond_life_info (splay_tree_value);
311 static int flush_reg_cond_reg_1 (splay_tree_node, void *);
312 static void flush_reg_cond_reg (struct propagate_block_info *, int);
313 static rtx elim_reg_cond (rtx, unsigned int);
314 static rtx ior_reg_cond (rtx, rtx, int);
315 static rtx not_reg_cond (rtx);
316 static rtx and_reg_cond (rtx, rtx, int);
319 static void attempt_auto_inc (struct propagate_block_info *, rtx, rtx, rtx,
321 static void find_auto_inc (struct propagate_block_info *, rtx, rtx);
322 static int try_pre_increment_1 (struct propagate_block_info *, rtx);
323 static int try_pre_increment (rtx, rtx, HOST_WIDE_INT);
325 static void mark_used_reg (struct propagate_block_info *, rtx, rtx, rtx);
326 static void mark_used_regs (struct propagate_block_info *, rtx, rtx, rtx);
327 void debug_flow_info (void);
328 static void add_to_mem_set_list (struct propagate_block_info *, rtx);
329 static int invalidate_mems_from_autoinc (rtx *, void *);
330 static void invalidate_mems_from_set (struct propagate_block_info *, rtx);
331 static void clear_log_links (sbitmap);
332 static int count_or_remove_death_notes_bb (basic_block, int);
334 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
335 note associated with the BLOCK. */
338 first_insn_after_basic_block_note (basic_block block)
342 /* Get the first instruction in the block. */
343 insn = BB_HEAD (block);
345 if (insn == NULL_RTX)
348 insn = NEXT_INSN (insn);
349 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
351 return NEXT_INSN (insn);
354 /* Perform data flow analysis for the whole control flow graph.
355 FLAGS is a set of PROP_* flags to be used in accumulating flow info. */
358 life_analysis (FILE *file, int flags)
360 #ifdef ELIMINABLE_REGS
362 static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS;
365 /* Record which registers will be eliminated. We use this in
368 CLEAR_HARD_REG_SET (elim_reg_set);
370 #ifdef ELIMINABLE_REGS
371 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
372 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
374 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
378 #ifdef CANNOT_CHANGE_MODE_CLASS
379 if (flags & PROP_REG_INFO)
380 init_subregs_of_mode ();
384 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES);
386 /* The post-reload life analysis have (on a global basis) the same
387 registers live as was computed by reload itself. elimination
388 Otherwise offsets and such may be incorrect.
390 Reload will make some registers as live even though they do not
393 We don't want to create new auto-incs after reload, since they
394 are unlikely to be useful and can cause problems with shared
396 if (reload_completed)
397 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
399 /* We want alias analysis information for local dead store elimination. */
400 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
401 init_alias_analysis ();
403 /* Always remove no-op moves. Do this before other processing so
404 that we don't have to keep re-scanning them. */
405 delete_noop_moves ();
407 /* Some targets can emit simpler epilogues if they know that sp was
408 not ever modified during the function. After reload, of course,
409 we've already emitted the epilogue so there's no sense searching. */
410 if (! reload_completed)
411 notice_stack_pointer_modification ();
413 /* Allocate and zero out data structures that will record the
414 data from lifetime analysis. */
415 allocate_reg_life_data ();
416 allocate_bb_life_data ();
418 /* Find the set of registers live on function exit. */
419 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
421 /* "Update" life info from zero. It'd be nice to begin the
422 relaxation with just the exit and noreturn blocks, but that set
423 is not immediately handy. */
425 if (flags & PROP_REG_INFO)
427 memset (regs_ever_live, 0, sizeof (regs_ever_live));
428 memset (regs_asm_clobbered, 0, sizeof (regs_asm_clobbered));
430 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
438 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
439 end_alias_analysis ();
442 dump_flow_info (file);
444 /* Removing dead insns should have made jumptables really dead. */
445 delete_dead_jumptables ();
448 /* A subroutine of verify_wide_reg, called through for_each_rtx.
449 Search for REGNO. If found, return 2 if it is not wider than
453 verify_wide_reg_1 (rtx *px, void *pregno)
456 unsigned int regno = *(int *) pregno;
458 if (REG_P (x) && REGNO (x) == regno)
460 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
467 /* A subroutine of verify_local_live_at_start. Search through insns
468 of BB looking for register REGNO. */
471 verify_wide_reg (int regno, basic_block bb)
473 rtx head = BB_HEAD (bb), end = BB_END (bb);
479 int r = for_each_rtx (&PATTERN (head), verify_wide_reg_1, ®no);
487 head = NEXT_INSN (head);
491 fprintf (dump_file, "Register %d died unexpectedly.\n", regno);
492 dump_bb (bb, dump_file, 0);
494 fatal_error ("internal consistency failure");
497 /* A subroutine of update_life_info. Verify that there are no untoward
498 changes in live_at_start during a local update. */
501 verify_local_live_at_start (regset new_live_at_start, basic_block bb)
503 if (reload_completed)
505 /* After reload, there are no pseudos, nor subregs of multi-word
506 registers. The regsets should exactly match. */
507 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
512 "live_at_start mismatch in bb %d, aborting\nNew:\n",
514 debug_bitmap_file (dump_file, new_live_at_start);
515 fputs ("Old:\n", dump_file);
516 dump_bb (bb, dump_file, 0);
518 fatal_error ("internal consistency failure");
524 reg_set_iterator rsi;
526 /* Find the set of changed registers. */
527 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
529 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i, rsi)
531 /* No registers should die. */
532 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
537 "Register %d died unexpectedly.\n", i);
538 dump_bb (bb, dump_file, 0);
540 fatal_error ("internal consistency failure");
542 /* Verify that the now-live register is wider than word_mode. */
543 verify_wide_reg (i, bb);
548 /* Updates life information starting with the basic blocks set in BLOCKS.
549 If BLOCKS is null, consider it to be the universal set.
551 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholing,
552 we are only expecting local modifications to basic blocks. If we find
553 extra registers live at the beginning of a block, then we either killed
554 useful data, or we have a broken split that wants data not provided.
555 If we find registers removed from live_at_start, that means we have
556 a broken peephole that is killing a register it shouldn't.
558 ??? This is not true in one situation -- when a pre-reload splitter
559 generates subregs of a multi-word pseudo, current life analysis will
560 lose the kill. So we _can_ have a pseudo go live. How irritating.
562 It is also not true when a peephole decides that it doesn't need one
563 or more of the inputs.
565 Including PROP_REG_INFO does not properly refresh regs_ever_live
566 unless the caller resets it to zero. */
569 update_life_info (sbitmap blocks, enum update_life_extent extent, int prop_flags)
572 regset_head tmp_head;
574 int stabilized_prop_flags = prop_flags;
577 tmp = INITIALIZE_REG_SET (tmp_head);
580 if ((prop_flags & PROP_REG_INFO) && !reg_deaths)
581 reg_deaths = xcalloc (sizeof (*reg_deaths), max_regno);
583 timevar_push ((extent == UPDATE_LIFE_LOCAL || blocks)
584 ? TV_LIFE_UPDATE : TV_LIFE);
586 /* Changes to the CFG are only allowed when
587 doing a global update for the entire CFG. */
588 gcc_assert (!(prop_flags & PROP_ALLOW_CFG_CHANGES)
589 || (extent != UPDATE_LIFE_LOCAL && !blocks));
591 /* For a global update, we go through the relaxation process again. */
592 if (extent != UPDATE_LIFE_LOCAL)
598 calculate_global_regs_live (blocks, blocks,
599 prop_flags & (PROP_SCAN_DEAD_CODE
600 | PROP_SCAN_DEAD_STORES
601 | PROP_ALLOW_CFG_CHANGES));
603 if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
604 != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
607 /* Removing dead code may allow the CFG to be simplified which
608 in turn may allow for further dead code detection / removal. */
609 FOR_EACH_BB_REVERSE (bb)
611 COPY_REG_SET (tmp, bb->global_live_at_end);
612 changed |= propagate_block (bb, tmp, NULL, NULL,
613 prop_flags & (PROP_SCAN_DEAD_CODE
614 | PROP_SCAN_DEAD_STORES
615 | PROP_KILL_DEAD_CODE));
618 /* Don't pass PROP_SCAN_DEAD_CODE or PROP_KILL_DEAD_CODE to
619 subsequent propagate_block calls, since removing or acting as
620 removing dead code can affect global register liveness, which
621 is supposed to be finalized for this call after this loop. */
622 stabilized_prop_flags
623 &= ~(PROP_SCAN_DEAD_CODE | PROP_SCAN_DEAD_STORES
624 | PROP_KILL_DEAD_CODE);
629 /* We repeat regardless of what cleanup_cfg says. If there were
630 instructions deleted above, that might have been only a
631 partial improvement (see MAX_MEM_SET_LIST_LEN usage).
632 Further improvement may be possible. */
633 cleanup_cfg (CLEANUP_EXPENSIVE);
635 /* Zap the life information from the last round. If we don't
636 do this, we can wind up with registers that no longer appear
637 in the code being marked live at entry. */
640 CLEAR_REG_SET (bb->global_live_at_start);
641 CLEAR_REG_SET (bb->global_live_at_end);
645 /* If asked, remove notes from the blocks we'll update. */
646 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
647 count_or_remove_death_notes (blocks, 1);
650 /* Clear log links in case we are asked to (re)compute them. */
651 if (prop_flags & PROP_LOG_LINKS)
652 clear_log_links (blocks);
656 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
658 bb = BASIC_BLOCK (i);
660 COPY_REG_SET (tmp, bb->global_live_at_end);
661 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags);
663 if (extent == UPDATE_LIFE_LOCAL)
664 verify_local_live_at_start (tmp, bb);
669 FOR_EACH_BB_REVERSE (bb)
671 COPY_REG_SET (tmp, bb->global_live_at_end);
673 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags);
675 if (extent == UPDATE_LIFE_LOCAL)
676 verify_local_live_at_start (tmp, bb);
682 if (prop_flags & PROP_REG_INFO)
684 reg_set_iterator rsi;
686 /* The only pseudos that are live at the beginning of the function
687 are those that were not set anywhere in the function. local-alloc
688 doesn't know how to handle these correctly, so mark them as not
689 local to any one basic block. */
690 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
691 FIRST_PSEUDO_REGISTER, i, rsi)
692 REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL;
694 /* We have a problem with any pseudoreg that lives across the setjmp.
695 ANSI says that if a user variable does not change in value between
696 the setjmp and the longjmp, then the longjmp preserves it. This
697 includes longjmp from a place where the pseudo appears dead.
698 (In principle, the value still exists if it is in scope.)
699 If the pseudo goes in a hard reg, some other value may occupy
700 that hard reg where this pseudo is dead, thus clobbering the pseudo.
701 Conclusion: such a pseudo must not go in a hard reg. */
702 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
703 FIRST_PSEUDO_REGISTER, i, rsi)
705 if (regno_reg_rtx[i] != 0)
707 REG_LIVE_LENGTH (i) = -1;
708 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
717 timevar_pop ((extent == UPDATE_LIFE_LOCAL || blocks)
718 ? TV_LIFE_UPDATE : TV_LIFE);
719 if (ndead && dump_file)
720 fprintf (dump_file, "deleted %i dead insns\n", ndead);
724 /* Update life information in all blocks where BB_DIRTY is set. */
727 update_life_info_in_dirty_blocks (enum update_life_extent extent, int prop_flags)
729 sbitmap update_life_blocks = sbitmap_alloc (last_basic_block);
734 sbitmap_zero (update_life_blocks);
737 if (extent == UPDATE_LIFE_LOCAL)
739 if (bb->flags & BB_DIRTY)
741 SET_BIT (update_life_blocks, bb->index);
747 /* ??? Bootstrap with -march=pentium4 fails to terminate
748 with only a partial life update. */
749 SET_BIT (update_life_blocks, bb->index);
750 if (bb->flags & BB_DIRTY)
756 retval = update_life_info (update_life_blocks, extent, prop_flags);
758 sbitmap_free (update_life_blocks);
762 /* Free the variables allocated by find_basic_blocks. */
765 free_basic_block_vars (void)
767 if (basic_block_info)
770 basic_block_info = NULL;
773 last_basic_block = 0;
775 ENTRY_BLOCK_PTR->aux = NULL;
776 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
777 EXIT_BLOCK_PTR->aux = NULL;
778 EXIT_BLOCK_PTR->global_live_at_start = NULL;
781 /* Delete any insns that copy a register to itself. */
784 delete_noop_moves (void)
792 for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb)); insn = next)
794 next = NEXT_INSN (insn);
795 if (INSN_P (insn) && noop_move_p (insn))
799 /* If we're about to remove the first insn of a libcall
800 then move the libcall note to the next real insn and
801 update the retval note. */
802 if ((note = find_reg_note (insn, REG_LIBCALL, NULL_RTX))
803 && XEXP (note, 0) != insn)
805 rtx new_libcall_insn = next_real_insn (insn);
806 rtx retval_note = find_reg_note (XEXP (note, 0),
807 REG_RETVAL, NULL_RTX);
808 REG_NOTES (new_libcall_insn)
809 = gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0),
810 REG_NOTES (new_libcall_insn));
811 XEXP (retval_note, 0) = new_libcall_insn;
814 delete_insn_and_edges (insn);
819 if (nnoops && dump_file)
820 fprintf (dump_file, "deleted %i noop moves", nnoops);
824 /* Delete any jump tables never referenced. We can't delete them at the
825 time of removing tablejump insn as they are referenced by the preceding
826 insns computing the destination, so we delay deleting and garbagecollect
827 them once life information is computed. */
829 delete_dead_jumptables (void)
832 for (insn = get_insns (); insn; insn = next)
834 next = NEXT_INSN (insn);
836 && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
838 && (GET_CODE (PATTERN (next)) == ADDR_VEC
839 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
842 fprintf (dump_file, "Dead jumptable %i removed\n", INSN_UID (insn));
843 delete_insn (NEXT_INSN (insn));
845 next = NEXT_INSN (next);
850 /* Determine if the stack pointer is constant over the life of the function.
851 Only useful before prologues have been emitted. */
854 notice_stack_pointer_modification_1 (rtx x, rtx pat ATTRIBUTE_UNUSED,
855 void *data ATTRIBUTE_UNUSED)
857 if (x == stack_pointer_rtx
858 /* The stack pointer is only modified indirectly as the result
859 of a push until later in flow. See the comments in rtl.texi
860 regarding Embedded Side-Effects on Addresses. */
862 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == RTX_AUTOINC
863 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
864 current_function_sp_is_unchanging = 0;
868 notice_stack_pointer_modification (void)
873 /* Assume that the stack pointer is unchanging if alloca hasn't
875 current_function_sp_is_unchanging = !current_function_calls_alloca;
876 if (! current_function_sp_is_unchanging)
880 FOR_BB_INSNS (bb, insn)
884 /* Check if insn modifies the stack pointer. */
885 note_stores (PATTERN (insn),
886 notice_stack_pointer_modification_1,
888 if (! current_function_sp_is_unchanging)
894 /* Mark a register in SET. Hard registers in large modes get all
895 of their component registers set as well. */
898 mark_reg (rtx reg, void *xset)
900 regset set = (regset) xset;
901 int regno = REGNO (reg);
903 gcc_assert (GET_MODE (reg) != BLKmode);
905 SET_REGNO_REG_SET (set, regno);
906 if (regno < FIRST_PSEUDO_REGISTER)
908 int n = hard_regno_nregs[regno][GET_MODE (reg)];
910 SET_REGNO_REG_SET (set, regno + n);
914 /* Mark those regs which are needed at the end of the function as live
915 at the end of the last basic block. */
918 mark_regs_live_at_end (regset set)
922 /* If exiting needs the right stack value, consider the stack pointer
923 live at the end of the function. */
924 if ((HAVE_epilogue && epilogue_completed)
925 || ! EXIT_IGNORE_STACK
926 || (! FRAME_POINTER_REQUIRED
927 && ! current_function_calls_alloca
928 && flag_omit_frame_pointer)
929 || current_function_sp_is_unchanging)
931 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
934 /* Mark the frame pointer if needed at the end of the function. If
935 we end up eliminating it, it will be removed from the live list
936 of each basic block by reload. */
938 if (! reload_completed || frame_pointer_needed)
940 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
941 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
942 /* If they are different, also mark the hard frame pointer as live. */
943 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
944 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
948 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
949 /* Many architectures have a GP register even without flag_pic.
950 Assume the pic register is not in use, or will be handled by
951 other means, if it is not fixed. */
952 if ((unsigned) PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
953 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
954 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
957 /* Mark all global registers, and all registers used by the epilogue
958 as being live at the end of the function since they may be
959 referenced by our caller. */
960 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
961 if (global_regs[i] || EPILOGUE_USES (i))
962 SET_REGNO_REG_SET (set, i);
964 if (HAVE_epilogue && epilogue_completed)
966 /* Mark all call-saved registers that we actually used. */
967 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
968 if (regs_ever_live[i] && ! LOCAL_REGNO (i)
969 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
970 SET_REGNO_REG_SET (set, i);
973 #ifdef EH_RETURN_DATA_REGNO
974 /* Mark the registers that will contain data for the handler. */
975 if (reload_completed && current_function_calls_eh_return)
978 unsigned regno = EH_RETURN_DATA_REGNO(i);
979 if (regno == INVALID_REGNUM)
981 SET_REGNO_REG_SET (set, regno);
984 #ifdef EH_RETURN_STACKADJ_RTX
985 if ((! HAVE_epilogue || ! epilogue_completed)
986 && current_function_calls_eh_return)
988 rtx tmp = EH_RETURN_STACKADJ_RTX;
989 if (tmp && REG_P (tmp))
993 #ifdef EH_RETURN_HANDLER_RTX
994 if ((! HAVE_epilogue || ! epilogue_completed)
995 && current_function_calls_eh_return)
997 rtx tmp = EH_RETURN_HANDLER_RTX;
998 if (tmp && REG_P (tmp))
1003 /* Mark function return value. */
1004 diddle_return_value (mark_reg, set);
1007 /* Propagate global life info around the graph of basic blocks. Begin
1008 considering blocks with their corresponding bit set in BLOCKS_IN.
1009 If BLOCKS_IN is null, consider it the universal set.
1011 BLOCKS_OUT is set for every block that was changed. */
1014 calculate_global_regs_live (sbitmap blocks_in, sbitmap blocks_out, int flags)
1016 basic_block *queue, *qhead, *qtail, *qend, bb;
1017 regset tmp, new_live_at_end, invalidated_by_call;
1018 regset_head tmp_head, invalidated_by_call_head;
1019 regset_head new_live_at_end_head;
1022 /* Some passes used to forget clear aux field of basic block causing
1023 sick behavior here. */
1024 #ifdef ENABLE_CHECKING
1025 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1026 gcc_assert (!bb->aux);
1029 tmp = INITIALIZE_REG_SET (tmp_head);
1030 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
1031 invalidated_by_call = INITIALIZE_REG_SET (invalidated_by_call_head);
1033 /* Inconveniently, this is only readily available in hard reg set form. */
1034 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
1035 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1036 SET_REGNO_REG_SET (invalidated_by_call, i);
1038 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1039 because the `head == tail' style test for an empty queue doesn't
1040 work with a full queue. */
1041 queue = xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
1043 qhead = qend = queue + n_basic_blocks + 2;
1045 /* Queue the blocks set in the initial mask. Do this in reverse block
1046 number order so that we are more likely for the first round to do
1047 useful work. We use AUX non-null to flag that the block is queued. */
1051 if (TEST_BIT (blocks_in, bb->index))
1066 /* We clean aux when we remove the initially-enqueued bbs, but we
1067 don't enqueue ENTRY and EXIT initially, so clean them upfront and
1069 ENTRY_BLOCK_PTR->aux = EXIT_BLOCK_PTR->aux = NULL;
1072 sbitmap_zero (blocks_out);
1074 /* We work through the queue until there are no more blocks. What
1075 is live at the end of this block is precisely the union of what
1076 is live at the beginning of all its successors. So, we set its
1077 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1078 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1079 this block by walking through the instructions in this block in
1080 reverse order and updating as we go. If that changed
1081 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1082 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1084 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1085 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1086 must either be live at the end of the block, or used within the
1087 block. In the latter case, it will certainly never disappear
1088 from GLOBAL_LIVE_AT_START. In the former case, the register
1089 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1090 for one of the successor blocks. By induction, that cannot
1092 while (qhead != qtail)
1094 int rescan, changed;
1104 /* Begin by propagating live_at_start from the successor blocks. */
1105 CLEAR_REG_SET (new_live_at_end);
1107 if (EDGE_COUNT (bb->succs) > 0)
1108 FOR_EACH_EDGE (e, ei, bb->succs)
1110 basic_block sb = e->dest;
1112 /* Call-clobbered registers die across exception and
1114 /* ??? Abnormal call edges ignored for the moment, as this gets
1115 confused by sibling call edges, which crashes reg-stack. */
1116 if (e->flags & EDGE_EH)
1118 bitmap_operation (tmp, sb->global_live_at_start,
1119 invalidated_by_call, BITMAP_AND_COMPL);
1120 IOR_REG_SET (new_live_at_end, tmp);
1123 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
1125 /* If a target saves one register in another (instead of on
1126 the stack) the save register will need to be live for EH. */
1127 if (e->flags & EDGE_EH)
1128 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1130 SET_REGNO_REG_SET (new_live_at_end, i);
1134 /* This might be a noreturn function that throws. And
1135 even if it isn't, getting the unwind info right helps
1137 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1139 SET_REGNO_REG_SET (new_live_at_end, i);
1142 /* The all-important stack pointer must always be live. */
1143 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
1145 /* Before reload, there are a few registers that must be forced
1146 live everywhere -- which might not already be the case for
1147 blocks within infinite loops. */
1148 if (! reload_completed)
1150 /* Any reference to any pseudo before reload is a potential
1151 reference of the frame pointer. */
1152 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
1154 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1155 /* Pseudos with argument area equivalences may require
1156 reloading via the argument pointer. */
1157 if (fixed_regs[ARG_POINTER_REGNUM])
1158 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
1161 /* Any constant, or pseudo with constant equivalences, may
1162 require reloading from memory using the pic register. */
1163 if ((unsigned) PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
1164 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
1165 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
1168 if (bb == ENTRY_BLOCK_PTR)
1170 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1174 /* On our first pass through this block, we'll go ahead and continue.
1175 Recognize first pass by local_set NULL. On subsequent passes, we
1176 get to skip out early if live_at_end wouldn't have changed. */
1178 if (bb->local_set == NULL)
1180 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1181 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1186 /* If any bits were removed from live_at_end, we'll have to
1187 rescan the block. This wouldn't be necessary if we had
1188 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1189 local_live is really dependent on live_at_end. */
1190 CLEAR_REG_SET (tmp);
1191 rescan = bitmap_operation (tmp, bb->global_live_at_end,
1192 new_live_at_end, BITMAP_AND_COMPL);
1196 /* If any of the registers in the new live_at_end set are
1197 conditionally set in this basic block, we must rescan.
1198 This is because conditional lifetimes at the end of the
1199 block do not just take the live_at_end set into account,
1200 but also the liveness at the start of each successor
1201 block. We can miss changes in those sets if we only
1202 compare the new live_at_end against the previous one. */
1203 CLEAR_REG_SET (tmp);
1204 rescan = bitmap_operation (tmp, new_live_at_end,
1205 bb->cond_local_set, BITMAP_AND);
1210 /* Find the set of changed bits. Take this opportunity
1211 to notice that this set is empty and early out. */
1212 CLEAR_REG_SET (tmp);
1213 changed = bitmap_operation (tmp, bb->global_live_at_end,
1214 new_live_at_end, BITMAP_XOR);
1218 /* If any of the changed bits overlap with local_set,
1219 we'll have to rescan the block. Detect overlap by
1220 the AND with ~local_set turning off bits. */
1221 rescan = bitmap_operation (tmp, tmp, bb->local_set,
1226 /* Let our caller know that BB changed enough to require its
1227 death notes updated. */
1229 SET_BIT (blocks_out, bb->index);
1233 /* Add to live_at_start the set of all registers in
1234 new_live_at_end that aren't in the old live_at_end. */
1236 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
1238 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1240 changed = bitmap_operation (bb->global_live_at_start,
1241 bb->global_live_at_start,
1248 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1250 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1251 into live_at_start. */
1252 propagate_block (bb, new_live_at_end, bb->local_set,
1253 bb->cond_local_set, flags);
1255 /* If live_at start didn't change, no need to go farther. */
1256 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
1259 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
1262 /* Queue all predecessors of BB so that we may re-examine
1263 their live_at_end. */
1264 FOR_EACH_EDGE (e, ei, bb->preds)
1266 basic_block pb = e->src;
1267 if (pb->aux == NULL)
1278 FREE_REG_SET (new_live_at_end);
1279 FREE_REG_SET (invalidated_by_call);
1283 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
1285 basic_block bb = BASIC_BLOCK (i);
1286 FREE_REG_SET (bb->local_set);
1287 FREE_REG_SET (bb->cond_local_set);
1294 FREE_REG_SET (bb->local_set);
1295 FREE_REG_SET (bb->cond_local_set);
1303 /* This structure is used to pass parameters to and from the
1304 the function find_regno_partial(). It is used to pass in the
1305 register number we are looking, as well as to return any rtx
1309 unsigned regno_to_find;
1311 } find_regno_partial_param;
1314 /* Find the rtx for the reg numbers specified in 'data' if it is
1315 part of an expression which only uses part of the register. Return
1316 it in the structure passed in. */
1318 find_regno_partial (rtx *ptr, void *data)
1320 find_regno_partial_param *param = (find_regno_partial_param *)data;
1321 unsigned reg = param->regno_to_find;
1322 param->retval = NULL_RTX;
1324 if (*ptr == NULL_RTX)
1327 switch (GET_CODE (*ptr))
1331 case STRICT_LOW_PART:
1332 if (REG_P (XEXP (*ptr, 0)) && REGNO (XEXP (*ptr, 0)) == reg)
1334 param->retval = XEXP (*ptr, 0);
1340 if (REG_P (SUBREG_REG (*ptr))
1341 && REGNO (SUBREG_REG (*ptr)) == reg)
1343 param->retval = SUBREG_REG (*ptr);
1355 /* Process all immediate successors of the entry block looking for pseudo
1356 registers which are live on entry. Find all of those whose first
1357 instance is a partial register reference of some kind, and initialize
1358 them to 0 after the entry block. This will prevent bit sets within
1359 registers whose value is unknown, and may contain some kind of sticky
1360 bits we don't want. */
1363 initialize_uninitialized_subregs (void)
1367 int reg, did_something = 0;
1368 find_regno_partial_param param;
1371 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
1373 basic_block bb = e->dest;
1374 regset map = bb->global_live_at_start;
1375 reg_set_iterator rsi;
1377 EXECUTE_IF_SET_IN_REG_SET (map, FIRST_PSEUDO_REGISTER, reg, rsi)
1379 int uid = REGNO_FIRST_UID (reg);
1382 /* Find an insn which mentions the register we are looking for.
1383 Its preferable to have an instance of the register's rtl since
1384 there may be various flags set which we need to duplicate.
1385 If we can't find it, its probably an automatic whose initial
1386 value doesn't matter, or hopefully something we don't care about. */
1387 for (i = get_insns (); i && INSN_UID (i) != uid; i = NEXT_INSN (i))
1391 /* Found the insn, now get the REG rtx, if we can. */
1392 param.regno_to_find = reg;
1393 for_each_rtx (&i, find_regno_partial, ¶m);
1394 if (param.retval != NULL_RTX)
1397 emit_move_insn (param.retval,
1398 CONST0_RTX (GET_MODE (param.retval)));
1399 insn = get_insns ();
1401 insert_insn_on_edge (insn, e);
1409 commit_edge_insertions ();
1410 return did_something;
1414 /* Subroutines of life analysis. */
1416 /* Allocate the permanent data structures that represent the results
1417 of life analysis. Not static since used also for stupid life analysis. */
1420 allocate_bb_life_data (void)
1424 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1426 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1427 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1430 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1434 allocate_reg_life_data (void)
1438 max_regno = max_reg_num ();
1439 gcc_assert (!reg_deaths);
1440 reg_deaths = xcalloc (sizeof (*reg_deaths), max_regno);
1442 /* Recalculate the register space, in case it has grown. Old style
1443 vector oriented regsets would set regset_{size,bytes} here also. */
1444 allocate_reg_info (max_regno, FALSE, FALSE);
1446 /* Reset all the data we'll collect in propagate_block and its
1448 for (i = 0; i < max_regno; i++)
1452 REG_N_DEATHS (i) = 0;
1453 REG_N_CALLS_CROSSED (i) = 0;
1454 REG_LIVE_LENGTH (i) = 0;
1456 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
1460 /* Delete dead instructions for propagate_block. */
1463 propagate_block_delete_insn (rtx insn)
1465 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
1467 /* If the insn referred to a label, and that label was attached to
1468 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1469 pretty much mandatory to delete it, because the ADDR_VEC may be
1470 referencing labels that no longer exist.
1472 INSN may reference a deleted label, particularly when a jump
1473 table has been optimized into a direct jump. There's no
1474 real good way to fix up the reference to the deleted label
1475 when the label is deleted, so we just allow it here. */
1477 if (inote && LABEL_P (inote))
1479 rtx label = XEXP (inote, 0);
1482 /* The label may be forced if it has been put in the constant
1483 pool. If that is the only use we must discard the table
1484 jump following it, but not the label itself. */
1485 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
1486 && (next = next_nonnote_insn (label)) != NULL
1488 && (GET_CODE (PATTERN (next)) == ADDR_VEC
1489 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
1491 rtx pat = PATTERN (next);
1492 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
1493 int len = XVECLEN (pat, diff_vec_p);
1496 for (i = 0; i < len; i++)
1497 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
1499 delete_insn_and_edges (next);
1504 delete_insn_and_edges (insn);
1508 /* Delete dead libcalls for propagate_block. Return the insn
1509 before the libcall. */
1512 propagate_block_delete_libcall (rtx insn, rtx note)
1514 rtx first = XEXP (note, 0);
1515 rtx before = PREV_INSN (first);
1517 delete_insn_chain_and_edges (first, insn);
1522 /* Update the life-status of regs for one insn. Return the previous insn. */
1525 propagate_one_insn (struct propagate_block_info *pbi, rtx insn)
1527 rtx prev = PREV_INSN (insn);
1528 int flags = pbi->flags;
1529 int insn_is_dead = 0;
1530 int libcall_is_dead = 0;
1534 if (! INSN_P (insn))
1537 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1538 if (flags & PROP_SCAN_DEAD_CODE)
1540 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
1541 libcall_is_dead = (insn_is_dead && note != 0
1542 && libcall_dead_p (pbi, note, insn));
1545 /* If an instruction consists of just dead store(s) on final pass,
1547 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
1549 /* If we're trying to delete a prologue or epilogue instruction
1550 that isn't flagged as possibly being dead, something is wrong.
1551 But if we are keeping the stack pointer depressed, we might well
1552 be deleting insns that are used to compute the amount to update
1553 it by, so they are fine. */
1554 if (reload_completed
1555 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1556 && (TYPE_RETURNS_STACK_DEPRESSED
1557 (TREE_TYPE (current_function_decl))))
1558 && (((HAVE_epilogue || HAVE_prologue)
1559 && prologue_epilogue_contains (insn))
1560 || (HAVE_sibcall_epilogue
1561 && sibcall_epilogue_contains (insn)))
1562 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
1563 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn);
1565 /* Record sets. Do this even for dead instructions, since they
1566 would have killed the values if they hadn't been deleted. */
1567 mark_set_regs (pbi, PATTERN (insn), insn);
1569 /* CC0 is now known to be dead. Either this insn used it,
1570 in which case it doesn't anymore, or clobbered it,
1571 so the next insn can't use it. */
1574 if (libcall_is_dead)
1575 prev = propagate_block_delete_libcall ( insn, note);
1579 /* If INSN contains a RETVAL note and is dead, but the libcall
1580 as a whole is not dead, then we want to remove INSN, but
1581 not the whole libcall sequence.
1583 However, we need to also remove the dangling REG_LIBCALL
1584 note so that we do not have mis-matched LIBCALL/RETVAL
1585 notes. In theory we could find a new location for the
1586 REG_RETVAL note, but it hardly seems worth the effort.
1588 NOTE at this point will be the RETVAL note if it exists. */
1594 = find_reg_note (XEXP (note, 0), REG_LIBCALL, NULL_RTX);
1595 remove_note (XEXP (note, 0), libcall_note);
1598 /* Similarly if INSN contains a LIBCALL note, remove the
1599 dangling REG_RETVAL note. */
1600 note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
1606 = find_reg_note (XEXP (note, 0), REG_RETVAL, NULL_RTX);
1607 remove_note (XEXP (note, 0), retval_note);
1610 /* Now delete INSN. */
1611 propagate_block_delete_insn (insn);
1617 /* See if this is an increment or decrement that can be merged into
1618 a following memory address. */
1621 rtx x = single_set (insn);
1623 /* Does this instruction increment or decrement a register? */
1624 if ((flags & PROP_AUTOINC)
1626 && REG_P (SET_DEST (x))
1627 && (GET_CODE (SET_SRC (x)) == PLUS
1628 || GET_CODE (SET_SRC (x)) == MINUS)
1629 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1630 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1631 /* Ok, look for a following memory ref we can combine with.
1632 If one is found, change the memory ref to a PRE_INC
1633 or PRE_DEC, cancel this insn, and return 1.
1634 Return 0 if nothing has been done. */
1635 && try_pre_increment_1 (pbi, insn))
1638 #endif /* AUTO_INC_DEC */
1640 CLEAR_REG_SET (pbi->new_set);
1642 /* If this is not the final pass, and this insn is copying the value of
1643 a library call and it's dead, don't scan the insns that perform the
1644 library call, so that the call's arguments are not marked live. */
1645 if (libcall_is_dead)
1647 /* Record the death of the dest reg. */
1648 mark_set_regs (pbi, PATTERN (insn), insn);
1650 insn = XEXP (note, 0);
1651 return PREV_INSN (insn);
1653 else if (GET_CODE (PATTERN (insn)) == SET
1654 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1655 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1656 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1657 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1659 /* We have an insn to pop a constant amount off the stack.
1660 (Such insns use PLUS regardless of the direction of the stack,
1661 and any insn to adjust the stack by a constant is always a pop
1663 These insns, if not dead stores, have no effect on life, though
1664 they do have an effect on the memory stores we are tracking. */
1665 invalidate_mems_from_set (pbi, stack_pointer_rtx);
1666 /* Still, we need to update local_set, lest ifcvt.c:dead_or_predicable
1667 concludes that the stack pointer is not modified. */
1668 mark_set_regs (pbi, PATTERN (insn), insn);
1673 /* Any regs live at the time of a call instruction must not go
1674 in a register clobbered by calls. Find all regs now live and
1675 record this for them. */
1677 if (CALL_P (insn) && (flags & PROP_REG_INFO))
1679 reg_set_iterator rsi;
1680 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i, rsi)
1681 REG_N_CALLS_CROSSED (i)++;
1684 /* Record sets. Do this even for dead instructions, since they
1685 would have killed the values if they hadn't been deleted. */
1686 mark_set_regs (pbi, PATTERN (insn), insn);
1696 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1697 cond = COND_EXEC_TEST (PATTERN (insn));
1699 /* Non-constant calls clobber memory, constant calls do not
1700 clobber memory, though they may clobber outgoing arguments
1702 if (! CONST_OR_PURE_CALL_P (insn))
1704 free_EXPR_LIST_list (&pbi->mem_set_list);
1705 pbi->mem_set_list_len = 0;
1708 invalidate_mems_from_set (pbi, stack_pointer_rtx);
1710 /* There may be extra registers to be clobbered. */
1711 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1713 note = XEXP (note, 1))
1714 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
1715 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
1716 cond, insn, pbi->flags);
1718 /* Calls change all call-used and global registers; sibcalls do not
1719 clobber anything that must be preserved at end-of-function,
1720 except for return values. */
1722 sibcall_p = SIBLING_CALL_P (insn);
1723 live_at_end = EXIT_BLOCK_PTR->global_live_at_start;
1724 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1725 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i)
1727 && REGNO_REG_SET_P (live_at_end, i)
1728 && ! refers_to_regno_p (i, i+1,
1729 current_function_return_rtx,
1732 enum rtx_code code = global_regs[i] ? SET : CLOBBER;
1733 /* We do not want REG_UNUSED notes for these registers. */
1734 mark_set_1 (pbi, code, regno_reg_rtx[i], cond, insn,
1735 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
1739 /* If an insn doesn't use CC0, it becomes dead since we assume
1740 that every insn clobbers it. So show it dead here;
1741 mark_used_regs will set it live if it is referenced. */
1746 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
1747 if ((flags & PROP_EQUAL_NOTES)
1748 && ((note = find_reg_note (insn, REG_EQUAL, NULL_RTX))
1749 || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX))))
1750 mark_used_regs (pbi, XEXP (note, 0), NULL_RTX, insn);
1752 /* Sometimes we may have inserted something before INSN (such as a move)
1753 when we make an auto-inc. So ensure we will scan those insns. */
1755 prev = PREV_INSN (insn);
1758 if (! insn_is_dead && CALL_P (insn))
1764 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1765 cond = COND_EXEC_TEST (PATTERN (insn));
1767 /* Calls use their arguments, and may clobber memory which
1768 address involves some register. */
1769 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1771 note = XEXP (note, 1))
1772 /* We find USE or CLOBBER entities in a FUNCTION_USAGE list: both
1773 of which mark_used_regs knows how to handle. */
1774 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0), cond, insn);
1776 /* The stack ptr is used (honorarily) by a CALL insn. */
1777 if ((flags & PROP_REG_INFO)
1778 && !REGNO_REG_SET_P (pbi->reg_live, STACK_POINTER_REGNUM))
1779 reg_deaths[STACK_POINTER_REGNUM] = pbi->insn_num;
1780 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
1782 /* Calls may also reference any of the global registers,
1783 so they are made live. */
1784 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1786 mark_used_reg (pbi, regno_reg_rtx[i], cond, insn);
1795 /* Initialize a propagate_block_info struct for public consumption.
1796 Note that the structure itself is opaque to this file, but that
1797 the user can use the regsets provided here. */
1799 struct propagate_block_info *
1800 init_propagate_block_info (basic_block bb, regset live, regset local_set,
1801 regset cond_local_set, int flags)
1803 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
1806 pbi->reg_live = live;
1807 pbi->mem_set_list = NULL_RTX;
1808 pbi->mem_set_list_len = 0;
1809 pbi->local_set = local_set;
1810 pbi->cond_local_set = cond_local_set;
1815 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
1816 pbi->reg_next_use = xcalloc (max_reg_num (), sizeof (rtx));
1818 pbi->reg_next_use = NULL;
1820 pbi->new_set = BITMAP_XMALLOC ();
1822 #ifdef HAVE_conditional_execution
1823 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
1824 free_reg_cond_life_info);
1825 pbi->reg_cond_reg = BITMAP_XMALLOC ();
1827 /* If this block ends in a conditional branch, for each register
1828 live from one side of the branch and not the other, record the
1829 register as conditionally dead. */
1830 if (JUMP_P (BB_END (bb))
1831 && any_condjump_p (BB_END (bb)))
1833 regset_head diff_head;
1834 regset diff = INITIALIZE_REG_SET (diff_head);
1835 basic_block bb_true, bb_false;
1838 /* Identify the successor blocks. */
1839 bb_true = EDGE_SUCC (bb, 0)->dest;
1840 if (EDGE_COUNT (bb->succs) > 1)
1842 bb_false = EDGE_SUCC (bb, 1)->dest;
1844 if (EDGE_SUCC (bb, 0)->flags & EDGE_FALLTHRU)
1846 basic_block t = bb_false;
1851 gcc_assert (EDGE_SUCC (bb, 1)->flags & EDGE_FALLTHRU);
1855 /* This can happen with a conditional jump to the next insn. */
1856 gcc_assert (JUMP_LABEL (BB_END (bb)) == BB_HEAD (bb_true));
1858 /* Simplest way to do nothing. */
1862 /* Compute which register lead different lives in the successors. */
1863 if (bitmap_operation (diff, bb_true->global_live_at_start,
1864 bb_false->global_live_at_start, BITMAP_XOR))
1866 /* Extract the condition from the branch. */
1867 rtx set_src = SET_SRC (pc_set (BB_END (bb)));
1868 rtx cond_true = XEXP (set_src, 0);
1869 rtx reg = XEXP (cond_true, 0);
1870 enum rtx_code inv_cond;
1872 if (GET_CODE (reg) == SUBREG)
1873 reg = SUBREG_REG (reg);
1875 /* We can only track conditional lifetimes if the condition is
1876 in the form of a reversible comparison of a register against
1877 zero. If the condition is more complex than that, then it is
1878 safe not to record any information. */
1879 inv_cond = reversed_comparison_code (cond_true, BB_END (bb));
1880 if (inv_cond != UNKNOWN
1882 && XEXP (cond_true, 1) == const0_rtx)
1885 = gen_rtx_fmt_ee (inv_cond,
1886 GET_MODE (cond_true), XEXP (cond_true, 0),
1887 XEXP (cond_true, 1));
1888 reg_set_iterator rsi;
1890 if (GET_CODE (XEXP (set_src, 1)) == PC)
1893 cond_false = cond_true;
1897 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
1899 /* For each such register, mark it conditionally dead. */
1900 EXECUTE_IF_SET_IN_REG_SET (diff, 0, i, rsi)
1902 struct reg_cond_life_info *rcli;
1905 rcli = xmalloc (sizeof (*rcli));
1907 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
1911 rcli->condition = cond;
1912 rcli->stores = const0_rtx;
1913 rcli->orig_condition = cond;
1915 splay_tree_insert (pbi->reg_cond_dead, i,
1916 (splay_tree_value) rcli);
1921 FREE_REG_SET (diff);
1925 /* If this block has no successors, any stores to the frame that aren't
1926 used later in the block are dead. So make a pass over the block
1927 recording any such that are made and show them dead at the end. We do
1928 a very conservative and simple job here. */
1930 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1931 && (TYPE_RETURNS_STACK_DEPRESSED
1932 (TREE_TYPE (current_function_decl))))
1933 && (flags & PROP_SCAN_DEAD_STORES)
1934 && (EDGE_COUNT (bb->succs) == 0
1935 || (EDGE_COUNT (bb->succs) == 1
1936 && EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
1937 && ! current_function_calls_eh_return)))
1940 for (insn = BB_END (bb); insn != BB_HEAD (bb); insn = PREV_INSN (insn))
1941 if (NONJUMP_INSN_P (insn)
1942 && (set = single_set (insn))
1943 && MEM_P (SET_DEST (set)))
1945 rtx mem = SET_DEST (set);
1946 rtx canon_mem = canon_rtx (mem);
1948 if (XEXP (canon_mem, 0) == frame_pointer_rtx
1949 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
1950 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
1951 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
1952 add_to_mem_set_list (pbi, canon_mem);
1959 /* Release a propagate_block_info struct. */
1962 free_propagate_block_info (struct propagate_block_info *pbi)
1964 free_EXPR_LIST_list (&pbi->mem_set_list);
1966 BITMAP_XFREE (pbi->new_set);
1968 #ifdef HAVE_conditional_execution
1969 splay_tree_delete (pbi->reg_cond_dead);
1970 BITMAP_XFREE (pbi->reg_cond_reg);
1973 if (pbi->flags & PROP_REG_INFO)
1975 int num = pbi->insn_num;
1977 reg_set_iterator rsi;
1979 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i, rsi)
1981 REG_LIVE_LENGTH (i) += num - reg_deaths[i];
1985 if (pbi->reg_next_use)
1986 free (pbi->reg_next_use);
1991 /* Compute the registers live at the beginning of a basic block BB from
1992 those live at the end.
1994 When called, REG_LIVE contains those live at the end. On return, it
1995 contains those live at the beginning.
1997 LOCAL_SET, if non-null, will be set with all registers killed
1998 unconditionally by this basic block.
1999 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
2000 killed conditionally by this basic block. If there is any unconditional
2001 set of a register, then the corresponding bit will be set in LOCAL_SET
2002 and cleared in COND_LOCAL_SET.
2003 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
2004 case, the resulting set will be equal to the union of the two sets that
2005 would otherwise be computed.
2007 Return nonzero if an INSN is deleted (i.e. by dead code removal). */
2010 propagate_block (basic_block bb, regset live, regset local_set,
2011 regset cond_local_set, int flags)
2013 struct propagate_block_info *pbi;
2017 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
2019 if (flags & PROP_REG_INFO)
2022 reg_set_iterator rsi;
2024 /* Process the regs live at the end of the block.
2025 Mark them as not local to any one basic block. */
2026 EXECUTE_IF_SET_IN_REG_SET (live, 0, i, rsi)
2027 REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL;
2030 /* Scan the block an insn at a time from end to beginning. */
2033 for (insn = BB_END (bb); ; insn = prev)
2035 /* If this is a call to `setjmp' et al, warn if any
2036 non-volatile datum is live. */
2037 if ((flags & PROP_REG_INFO)
2039 && find_reg_note (insn, REG_SETJMP, NULL))
2040 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
2042 prev = propagate_one_insn (pbi, insn);
2044 changed |= insn != get_insns ();
2046 changed |= NEXT_INSN (prev) != insn;
2048 if (insn == BB_HEAD (bb))
2052 free_propagate_block_info (pbi);
2057 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2058 (SET expressions whose destinations are registers dead after the insn).
2059 NEEDED is the regset that says which regs are alive after the insn.
2061 Unless CALL_OK is nonzero, an insn is needed if it contains a CALL.
2063 If X is the entire body of an insn, NOTES contains the reg notes
2064 pertaining to the insn. */
2067 insn_dead_p (struct propagate_block_info *pbi, rtx x, int call_ok,
2068 rtx notes ATTRIBUTE_UNUSED)
2070 enum rtx_code code = GET_CODE (x);
2072 /* Don't eliminate insns that may trap. */
2073 if (flag_non_call_exceptions && may_trap_p (x))
2077 /* As flow is invoked after combine, we must take existing AUTO_INC
2078 expressions into account. */
2079 for (; notes; notes = XEXP (notes, 1))
2081 if (REG_NOTE_KIND (notes) == REG_INC)
2083 int regno = REGNO (XEXP (notes, 0));
2085 /* Don't delete insns to set global regs. */
2086 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2087 || REGNO_REG_SET_P (pbi->reg_live, regno))
2093 /* If setting something that's a reg or part of one,
2094 see if that register's altered value will be live. */
2098 rtx r = SET_DEST (x);
2101 if (GET_CODE (r) == CC0)
2102 return ! pbi->cc0_live;
2105 /* A SET that is a subroutine call cannot be dead. */
2106 if (GET_CODE (SET_SRC (x)) == CALL)
2112 /* Don't eliminate loads from volatile memory or volatile asms. */
2113 else if (volatile_refs_p (SET_SRC (x)))
2120 if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode)
2123 canon_r = canon_rtx (r);
2125 /* Walk the set of memory locations we are currently tracking
2126 and see if one is an identical match to this memory location.
2127 If so, this memory write is dead (remember, we're walking
2128 backwards from the end of the block to the start). Since
2129 rtx_equal_p does not check the alias set or flags, we also
2130 must have the potential for them to conflict (anti_dependence). */
2131 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
2132 if (anti_dependence (r, XEXP (temp, 0)))
2134 rtx mem = XEXP (temp, 0);
2136 if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0))
2137 && (GET_MODE_SIZE (GET_MODE (canon_r))
2138 <= GET_MODE_SIZE (GET_MODE (mem))))
2142 /* Check if memory reference matches an auto increment. Only
2143 post increment/decrement or modify are valid. */
2144 if (GET_MODE (mem) == GET_MODE (r)
2145 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
2146 || GET_CODE (XEXP (mem, 0)) == POST_INC
2147 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
2148 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
2149 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
2156 while (GET_CODE (r) == SUBREG
2157 || GET_CODE (r) == STRICT_LOW_PART
2158 || GET_CODE (r) == ZERO_EXTRACT)
2163 int regno = REGNO (r);
2166 if (REGNO_REG_SET_P (pbi->reg_live, regno))
2169 /* If this is a hard register, verify that subsequent
2170 words are not needed. */
2171 if (regno < FIRST_PSEUDO_REGISTER)
2173 int n = hard_regno_nregs[regno][GET_MODE (r)];
2176 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
2180 /* Don't delete insns to set global regs. */
2181 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2184 /* Make sure insns to set the stack pointer aren't deleted. */
2185 if (regno == STACK_POINTER_REGNUM)
2188 /* ??? These bits might be redundant with the force live bits
2189 in calculate_global_regs_live. We would delete from
2190 sequential sets; whether this actually affects real code
2191 for anything but the stack pointer I don't know. */
2192 /* Make sure insns to set the frame pointer aren't deleted. */
2193 if (regno == FRAME_POINTER_REGNUM
2194 && (! reload_completed || frame_pointer_needed))
2196 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2197 if (regno == HARD_FRAME_POINTER_REGNUM
2198 && (! reload_completed || frame_pointer_needed))
2202 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2203 /* Make sure insns to set arg pointer are never deleted
2204 (if the arg pointer isn't fixed, there will be a USE
2205 for it, so we can treat it normally). */
2206 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2210 /* Otherwise, the set is dead. */
2216 /* If performing several activities, insn is dead if each activity
2217 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2218 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2220 else if (code == PARALLEL)
2222 int i = XVECLEN (x, 0);
2224 for (i--; i >= 0; i--)
2225 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
2226 && GET_CODE (XVECEXP (x, 0, i)) != USE
2227 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
2233 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2234 is not necessarily true for hard registers until after reload. */
2235 else if (code == CLOBBER)
2237 if (REG_P (XEXP (x, 0))
2238 && (REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
2239 || reload_completed)
2240 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
2244 /* ??? A base USE is a historical relic. It ought not be needed anymore.
2245 Instances where it is still used are either (1) temporary and the USE
2246 escaped the pass, (2) cruft and the USE need not be emitted anymore,
2247 or (3) hiding bugs elsewhere that are not properly representing data
2253 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2254 return 1 if the entire library call is dead.
2255 This is true if INSN copies a register (hard or pseudo)
2256 and if the hard return reg of the call insn is dead.
2257 (The caller should have tested the destination of the SET inside
2258 INSN already for death.)
2260 If this insn doesn't just copy a register, then we don't
2261 have an ordinary libcall. In that case, cse could not have
2262 managed to substitute the source for the dest later on,
2263 so we can assume the libcall is dead.
2265 PBI is the block info giving pseudoregs live before this insn.
2266 NOTE is the REG_RETVAL note of the insn. */
2269 libcall_dead_p (struct propagate_block_info *pbi, rtx note, rtx insn)
2271 rtx x = single_set (insn);
2275 rtx r = SET_SRC (x);
2279 rtx call = XEXP (note, 0);
2283 /* Find the call insn. */
2284 while (call != insn && !CALL_P (call))
2285 call = NEXT_INSN (call);
2287 /* If there is none, do nothing special,
2288 since ordinary death handling can understand these insns. */
2292 /* See if the hard reg holding the value is dead.
2293 If this is a PARALLEL, find the call within it. */
2294 call_pat = PATTERN (call);
2295 if (GET_CODE (call_pat) == PARALLEL)
2297 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
2298 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
2299 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
2302 /* This may be a library call that is returning a value
2303 via invisible pointer. Do nothing special, since
2304 ordinary death handling can understand these insns. */
2308 call_pat = XVECEXP (call_pat, 0, i);
2311 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
2317 /* 1 if register REGNO was alive at a place where `setjmp' was called
2318 and was set more than once or is an argument.
2319 Such regs may be clobbered by `longjmp'. */
2322 regno_clobbered_at_setjmp (int regno)
2324 if (n_basic_blocks == 0)
2327 return ((REG_N_SETS (regno) > 1
2328 || REGNO_REG_SET_P (ENTRY_BLOCK_PTR->global_live_at_end, regno))
2329 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
2332 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2333 maximal list size; look for overlaps in mode and select the largest. */
2335 add_to_mem_set_list (struct propagate_block_info *pbi, rtx mem)
2339 /* We don't know how large a BLKmode store is, so we must not
2340 take them into consideration. */
2341 if (GET_MODE (mem) == BLKmode)
2344 for (i = pbi->mem_set_list; i ; i = XEXP (i, 1))
2346 rtx e = XEXP (i, 0);
2347 if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0)))
2349 if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e)))
2352 /* If we must store a copy of the mem, we can just modify
2353 the mode of the stored copy. */
2354 if (pbi->flags & PROP_AUTOINC)
2355 PUT_MODE (e, GET_MODE (mem));
2364 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN)
2367 /* Store a copy of mem, otherwise the address may be
2368 scrogged by find_auto_inc. */
2369 if (pbi->flags & PROP_AUTOINC)
2370 mem = shallow_copy_rtx (mem);
2372 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
2373 pbi->mem_set_list_len++;
2377 /* INSN references memory, possibly using autoincrement addressing modes.
2378 Find any entries on the mem_set_list that need to be invalidated due
2379 to an address change. */
2382 invalidate_mems_from_autoinc (rtx *px, void *data)
2385 struct propagate_block_info *pbi = data;
2387 if (GET_RTX_CLASS (GET_CODE (x)) == RTX_AUTOINC)
2389 invalidate_mems_from_set (pbi, XEXP (x, 0));
2396 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2399 invalidate_mems_from_set (struct propagate_block_info *pbi, rtx exp)
2401 rtx temp = pbi->mem_set_list;
2402 rtx prev = NULL_RTX;
2407 next = XEXP (temp, 1);
2408 if (reg_overlap_mentioned_p (exp, XEXP (temp, 0)))
2410 /* Splice this entry out of the list. */
2412 XEXP (prev, 1) = next;
2414 pbi->mem_set_list = next;
2415 free_EXPR_LIST_node (temp);
2416 pbi->mem_set_list_len--;
2424 /* Process the registers that are set within X. Their bits are set to
2425 1 in the regset DEAD, because they are dead prior to this insn.
2427 If INSN is nonzero, it is the insn being processed.
2429 FLAGS is the set of operations to perform. */
2432 mark_set_regs (struct propagate_block_info *pbi, rtx x, rtx insn)
2434 rtx cond = NULL_RTX;
2437 int flags = pbi->flags;
2440 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2442 if (REG_NOTE_KIND (link) == REG_INC)
2443 mark_set_1 (pbi, SET, XEXP (link, 0),
2444 (GET_CODE (x) == COND_EXEC
2445 ? COND_EXEC_TEST (x) : NULL_RTX),
2449 switch (code = GET_CODE (x))
2452 if (GET_CODE (XEXP (x, 1)) == ASM_OPERANDS)
2453 flags |= PROP_ASM_SCAN;
2456 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, flags);
2460 cond = COND_EXEC_TEST (x);
2461 x = COND_EXEC_CODE (x);
2468 /* We must scan forwards. If we have an asm, we need to set
2469 the PROP_ASM_SCAN flag before scanning the clobbers. */
2470 for (i = 0; i < XVECLEN (x, 0); i++)
2472 rtx sub = XVECEXP (x, 0, i);
2473 switch (code = GET_CODE (sub))
2478 cond = COND_EXEC_TEST (sub);
2479 sub = COND_EXEC_CODE (sub);
2480 if (GET_CODE (sub) == SET)
2482 if (GET_CODE (sub) == CLOBBER)
2488 if (GET_CODE (XEXP (sub, 1)) == ASM_OPERANDS)
2489 flags |= PROP_ASM_SCAN;
2493 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, flags);
2497 flags |= PROP_ASM_SCAN;
2512 /* Process a single set, which appears in INSN. REG (which may not
2513 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2514 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2515 If the set is conditional (because it appear in a COND_EXEC), COND
2516 will be the condition. */
2519 mark_set_1 (struct propagate_block_info *pbi, enum rtx_code code, rtx reg, rtx cond, rtx insn, int flags)
2521 int regno_first = -1, regno_last = -1;
2522 unsigned long not_dead = 0;
2525 /* Modifying just one hardware register of a multi-reg value or just a
2526 byte field of a register does not mean the value from before this insn
2527 is now dead. Of course, if it was dead after it's unused now. */
2529 switch (GET_CODE (reg))
2532 /* Some targets place small structures in registers for return values of
2533 functions. We have to detect this case specially here to get correct
2534 flow information. */
2535 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
2536 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
2537 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
2543 case STRICT_LOW_PART:
2544 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2546 reg = XEXP (reg, 0);
2547 while (GET_CODE (reg) == SUBREG
2548 || GET_CODE (reg) == ZERO_EXTRACT
2549 || GET_CODE (reg) == SIGN_EXTRACT
2550 || GET_CODE (reg) == STRICT_LOW_PART);
2553 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
2557 regno_last = regno_first = REGNO (reg);
2558 if (regno_first < FIRST_PSEUDO_REGISTER)
2559 regno_last += hard_regno_nregs[regno_first][GET_MODE (reg)] - 1;
2563 if (REG_P (SUBREG_REG (reg)))
2565 enum machine_mode outer_mode = GET_MODE (reg);
2566 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
2568 /* Identify the range of registers affected. This is moderately
2569 tricky for hard registers. See alter_subreg. */
2571 regno_last = regno_first = REGNO (SUBREG_REG (reg));
2572 if (regno_first < FIRST_PSEUDO_REGISTER)
2574 regno_first += subreg_regno_offset (regno_first, inner_mode,
2577 regno_last = (regno_first
2578 + hard_regno_nregs[regno_first][outer_mode] - 1);
2580 /* Since we've just adjusted the register number ranges, make
2581 sure REG matches. Otherwise some_was_live will be clear
2582 when it shouldn't have been, and we'll create incorrect
2583 REG_UNUSED notes. */
2584 reg = gen_rtx_REG (outer_mode, regno_first);
2588 /* If the number of words in the subreg is less than the number
2589 of words in the full register, we have a well-defined partial
2590 set. Otherwise the high bits are undefined.
2592 This is only really applicable to pseudos, since we just took
2593 care of multi-word hard registers. */
2594 if (((GET_MODE_SIZE (outer_mode)
2595 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
2596 < ((GET_MODE_SIZE (inner_mode)
2597 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
2598 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
2601 reg = SUBREG_REG (reg);
2605 reg = SUBREG_REG (reg);
2612 /* If this set is a MEM, then it kills any aliased writes.
2613 If this set is a REG, then it kills any MEMs which use the reg. */
2614 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
2617 invalidate_mems_from_set (pbi, reg);
2619 /* If the memory reference had embedded side effects (autoincrement
2620 address modes. Then we may need to kill some entries on the
2622 if (insn && MEM_P (reg))
2623 for_each_rtx (&PATTERN (insn), invalidate_mems_from_autoinc, pbi);
2625 if (MEM_P (reg) && ! side_effects_p (reg)
2626 /* ??? With more effort we could track conditional memory life. */
2628 add_to_mem_set_list (pbi, canon_rtx (reg));
2632 && ! (regno_first == FRAME_POINTER_REGNUM
2633 && (! reload_completed || frame_pointer_needed))
2634 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2635 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
2636 && (! reload_completed || frame_pointer_needed))
2638 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2639 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
2643 int some_was_live = 0, some_was_dead = 0;
2645 for (i = regno_first; i <= regno_last; ++i)
2647 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
2650 /* Order of the set operation matters here since both
2651 sets may be the same. */
2652 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
2653 if (cond != NULL_RTX
2654 && ! REGNO_REG_SET_P (pbi->local_set, i))
2655 SET_REGNO_REG_SET (pbi->cond_local_set, i);
2657 SET_REGNO_REG_SET (pbi->local_set, i);
2659 if (code != CLOBBER)
2660 SET_REGNO_REG_SET (pbi->new_set, i);
2662 some_was_live |= needed_regno;
2663 some_was_dead |= ! needed_regno;
2666 #ifdef HAVE_conditional_execution
2667 /* Consider conditional death in deciding that the register needs
2669 if (some_was_live && ! not_dead
2670 /* The stack pointer is never dead. Well, not strictly true,
2671 but it's very difficult to tell from here. Hopefully
2672 combine_stack_adjustments will fix up the most egregious
2674 && regno_first != STACK_POINTER_REGNUM)
2676 for (i = regno_first; i <= regno_last; ++i)
2677 if (! mark_regno_cond_dead (pbi, i, cond))
2678 not_dead |= ((unsigned long) 1) << (i - regno_first);
2682 /* Additional data to record if this is the final pass. */
2683 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
2684 | PROP_DEATH_NOTES | PROP_AUTOINC))
2687 int blocknum = pbi->bb->index;
2690 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2692 y = pbi->reg_next_use[regno_first];
2694 /* The next use is no longer next, since a store intervenes. */
2695 for (i = regno_first; i <= regno_last; ++i)
2696 pbi->reg_next_use[i] = 0;
2699 if (flags & PROP_REG_INFO)
2701 for (i = regno_first; i <= regno_last; ++i)
2703 /* Count (weighted) references, stores, etc. This counts a
2704 register twice if it is modified, but that is correct. */
2705 REG_N_SETS (i) += 1;
2706 REG_N_REFS (i) += 1;
2707 REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb);
2709 /* The insns where a reg is live are normally counted
2710 elsewhere, but we want the count to include the insn
2711 where the reg is set, and the normal counting mechanism
2712 would not count it. */
2713 REG_LIVE_LENGTH (i) += 1;
2716 /* If this is a hard reg, record this function uses the reg. */
2717 if (regno_first < FIRST_PSEUDO_REGISTER)
2719 for (i = regno_first; i <= regno_last; i++)
2720 regs_ever_live[i] = 1;
2721 if (flags & PROP_ASM_SCAN)
2722 for (i = regno_first; i <= regno_last; i++)
2723 regs_asm_clobbered[i] = 1;
2727 /* Keep track of which basic blocks each reg appears in. */
2728 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
2729 REG_BASIC_BLOCK (regno_first) = blocknum;
2730 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
2731 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
2735 if (! some_was_dead)
2737 if (flags & PROP_LOG_LINKS)
2739 /* Make a logical link from the next following insn
2740 that uses this register, back to this insn.
2741 The following insns have already been processed.
2743 We don't build a LOG_LINK for hard registers containing
2744 in ASM_OPERANDs. If these registers get replaced,
2745 we might wind up changing the semantics of the insn,
2746 even if reload can make what appear to be valid
2749 We don't build a LOG_LINK for global registers to
2750 or from a function call. We don't want to let
2751 combine think that it knows what is going on with
2752 global registers. */
2753 if (y && (BLOCK_NUM (y) == blocknum)
2754 && (regno_first >= FIRST_PSEUDO_REGISTER
2755 || (asm_noperands (PATTERN (y)) < 0
2756 && ! ((CALL_P (insn)
2758 && global_regs[regno_first]))))
2759 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
2764 else if (! some_was_live)
2766 if (flags & PROP_REG_INFO)
2767 REG_N_DEATHS (regno_first) += 1;
2769 if (flags & PROP_DEATH_NOTES)
2771 /* Note that dead stores have already been deleted
2772 when possible. If we get here, we have found a
2773 dead store that cannot be eliminated (because the
2774 same insn does something useful). Indicate this
2775 by marking the reg being set as dying here. */
2777 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2782 if (flags & PROP_DEATH_NOTES)
2784 /* This is a case where we have a multi-word hard register
2785 and some, but not all, of the words of the register are
2786 needed in subsequent insns. Write REG_UNUSED notes
2787 for those parts that were not needed. This case should
2790 for (i = regno_first; i <= regno_last; ++i)
2791 if (! REGNO_REG_SET_P (pbi->reg_live, i))
2793 = alloc_EXPR_LIST (REG_UNUSED,
2800 /* Mark the register as being dead. */
2802 /* The stack pointer is never dead. Well, not strictly true,
2803 but it's very difficult to tell from here. Hopefully
2804 combine_stack_adjustments will fix up the most egregious
2806 && regno_first != STACK_POINTER_REGNUM)
2808 for (i = regno_first; i <= regno_last; ++i)
2809 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
2811 if ((pbi->flags & PROP_REG_INFO)
2812 && REGNO_REG_SET_P (pbi->reg_live, i))
2814 REG_LIVE_LENGTH (i) += pbi->insn_num - reg_deaths[i];
2817 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
2821 else if (REG_P (reg))
2823 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2824 pbi->reg_next_use[regno_first] = 0;
2826 if ((flags & PROP_REG_INFO) != 0
2827 && (flags & PROP_ASM_SCAN) != 0
2828 && regno_first < FIRST_PSEUDO_REGISTER)
2830 for (i = regno_first; i <= regno_last; i++)
2831 regs_asm_clobbered[i] = 1;
2835 /* If this is the last pass and this is a SCRATCH, show it will be dying
2836 here and count it. */
2837 else if (GET_CODE (reg) == SCRATCH)
2839 if (flags & PROP_DEATH_NOTES)
2841 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2845 #ifdef HAVE_conditional_execution
2846 /* Mark REGNO conditionally dead.
2847 Return true if the register is now unconditionally dead. */
2850 mark_regno_cond_dead (struct propagate_block_info *pbi, int regno, rtx cond)
2852 /* If this is a store to a predicate register, the value of the
2853 predicate is changing, we don't know that the predicate as seen
2854 before is the same as that seen after. Flush all dependent
2855 conditions from reg_cond_dead. This will make all such
2856 conditionally live registers unconditionally live. */
2857 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
2858 flush_reg_cond_reg (pbi, regno);
2860 /* If this is an unconditional store, remove any conditional
2861 life that may have existed. */
2862 if (cond == NULL_RTX)
2863 splay_tree_remove (pbi->reg_cond_dead, regno);
2866 splay_tree_node node;
2867 struct reg_cond_life_info *rcli;
2870 /* Otherwise this is a conditional set. Record that fact.
2871 It may have been conditionally used, or there may be a
2872 subsequent set with a complimentary condition. */
2874 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
2877 /* The register was unconditionally live previously.
2878 Record the current condition as the condition under
2879 which it is dead. */
2880 rcli = xmalloc (sizeof (*rcli));
2881 rcli->condition = cond;
2882 rcli->stores = cond;
2883 rcli->orig_condition = const0_rtx;
2884 splay_tree_insert (pbi->reg_cond_dead, regno,
2885 (splay_tree_value) rcli);
2887 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2889 /* Not unconditionally dead. */
2894 /* The register was conditionally live previously.
2895 Add the new condition to the old. */
2896 rcli = (struct reg_cond_life_info *) node->value;
2897 ncond = rcli->condition;
2898 ncond = ior_reg_cond (ncond, cond, 1);
2899 if (rcli->stores == const0_rtx)
2900 rcli->stores = cond;
2901 else if (rcli->stores != const1_rtx)
2902 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
2904 /* If the register is now unconditionally dead, remove the entry
2905 in the splay_tree. A register is unconditionally dead if the
2906 dead condition ncond is true. A register is also unconditionally
2907 dead if the sum of all conditional stores is an unconditional
2908 store (stores is true), and the dead condition is identically the
2909 same as the original dead condition initialized at the end of
2910 the block. This is a pointer compare, not an rtx_equal_p
2912 if (ncond == const1_rtx
2913 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
2914 splay_tree_remove (pbi->reg_cond_dead, regno);
2917 rcli->condition = ncond;
2919 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2921 /* Not unconditionally dead. */
2930 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2933 free_reg_cond_life_info (splay_tree_value value)
2935 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
2939 /* Helper function for flush_reg_cond_reg. */
2942 flush_reg_cond_reg_1 (splay_tree_node node, void *data)
2944 struct reg_cond_life_info *rcli;
2945 int *xdata = (int *) data;
2946 unsigned int regno = xdata[0];
2948 /* Don't need to search if last flushed value was farther on in
2949 the in-order traversal. */
2950 if (xdata[1] >= (int) node->key)
2953 /* Splice out portions of the expression that refer to regno. */
2954 rcli = (struct reg_cond_life_info *) node->value;
2955 rcli->condition = elim_reg_cond (rcli->condition, regno);
2956 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
2957 rcli->stores = elim_reg_cond (rcli->stores, regno);
2959 /* If the entire condition is now false, signal the node to be removed. */
2960 if (rcli->condition == const0_rtx)
2962 xdata[1] = node->key;
2966 gcc_assert (rcli->condition != const1_rtx);
2971 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2974 flush_reg_cond_reg (struct propagate_block_info *pbi, int regno)
2980 while (splay_tree_foreach (pbi->reg_cond_dead,
2981 flush_reg_cond_reg_1, pair) == -1)
2982 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
2984 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
2987 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2988 For ior/and, the ADD flag determines whether we want to add the new
2989 condition X to the old one unconditionally. If it is zero, we will
2990 only return a new expression if X allows us to simplify part of
2991 OLD, otherwise we return NULL to the caller.
2992 If ADD is nonzero, we will return a new condition in all cases. The
2993 toplevel caller of one of these functions should always pass 1 for
2997 ior_reg_cond (rtx old, rtx x, int add)
3001 if (COMPARISON_P (old))
3003 if (COMPARISON_P (x)
3004 && REVERSE_CONDEXEC_PREDICATES_P (x, old)
3005 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3007 if (GET_CODE (x) == GET_CODE (old)
3008 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3012 return gen_rtx_IOR (0, old, x);
3015 switch (GET_CODE (old))
3018 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3019 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3020 if (op0 != NULL || op1 != NULL)
3022 if (op0 == const0_rtx)
3023 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3024 if (op1 == const0_rtx)
3025 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3026 if (op0 == const1_rtx || op1 == const1_rtx)
3029 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3030 else if (rtx_equal_p (x, op0))
3031 /* (x | A) | x ~ (x | A). */
3034 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3035 else if (rtx_equal_p (x, op1))
3036 /* (A | x) | x ~ (A | x). */
3038 return gen_rtx_IOR (0, op0, op1);
3042 return gen_rtx_IOR (0, old, x);
3045 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3046 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3047 if (op0 != NULL || op1 != NULL)
3049 if (op0 == const1_rtx)
3050 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3051 if (op1 == const1_rtx)
3052 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3053 if (op0 == const0_rtx || op1 == const0_rtx)
3056 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3057 else if (rtx_equal_p (x, op0))
3058 /* (x & A) | x ~ x. */
3061 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3062 else if (rtx_equal_p (x, op1))
3063 /* (A & x) | x ~ x. */
3065 return gen_rtx_AND (0, op0, op1);
3069 return gen_rtx_IOR (0, old, x);
3072 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3074 return not_reg_cond (op0);
3077 return gen_rtx_IOR (0, old, x);
3085 not_reg_cond (rtx x)
3087 if (x == const0_rtx)
3089 else if (x == const1_rtx)
3091 if (GET_CODE (x) == NOT)
3093 if (COMPARISON_P (x)
3094 && REG_P (XEXP (x, 0)))
3096 gcc_assert (XEXP (x, 1) == const0_rtx);
3098 return gen_rtx_fmt_ee (reversed_comparison_code (x, NULL),
3099 VOIDmode, XEXP (x, 0), const0_rtx);
3101 return gen_rtx_NOT (0, x);
3105 and_reg_cond (rtx old, rtx x, int add)
3109 if (COMPARISON_P (old))
3111 if (COMPARISON_P (x)
3112 && GET_CODE (x) == reversed_comparison_code (old, NULL)
3113 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3115 if (GET_CODE (x) == GET_CODE (old)
3116 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3120 return gen_rtx_AND (0, old, x);
3123 switch (GET_CODE (old))
3126 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3127 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3128 if (op0 != NULL || op1 != NULL)
3130 if (op0 == const0_rtx)
3131 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3132 if (op1 == const0_rtx)
3133 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3134 if (op0 == const1_rtx || op1 == const1_rtx)
3137 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3138 else if (rtx_equal_p (x, op0))
3139 /* (x | A) & x ~ x. */
3142 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3143 else if (rtx_equal_p (x, op1))
3144 /* (A | x) & x ~ x. */
3146 return gen_rtx_IOR (0, op0, op1);
3150 return gen_rtx_AND (0, old, x);
3153 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3154 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3155 if (op0 != NULL || op1 != NULL)
3157 if (op0 == const1_rtx)
3158 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3159 if (op1 == const1_rtx)
3160 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3161 if (op0 == const0_rtx || op1 == const0_rtx)
3164 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3165 else if (rtx_equal_p (x, op0))
3166 /* (x & A) & x ~ (x & A). */
3169 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3170 else if (rtx_equal_p (x, op1))
3171 /* (A & x) & x ~ (A & x). */
3173 return gen_rtx_AND (0, op0, op1);
3177 return gen_rtx_AND (0, old, x);
3180 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3182 return not_reg_cond (op0);
3185 return gen_rtx_AND (0, old, x);
3192 /* Given a condition X, remove references to reg REGNO and return the
3193 new condition. The removal will be done so that all conditions
3194 involving REGNO are considered to evaluate to false. This function
3195 is used when the value of REGNO changes. */
3198 elim_reg_cond (rtx x, unsigned int regno)
3202 if (COMPARISON_P (x))
3204 if (REGNO (XEXP (x, 0)) == regno)
3209 switch (GET_CODE (x))
3212 op0 = elim_reg_cond (XEXP (x, 0), regno);
3213 op1 = elim_reg_cond (XEXP (x, 1), regno);
3214 if (op0 == const0_rtx || op1 == const0_rtx)
3216 if (op0 == const1_rtx)
3218 if (op1 == const1_rtx)
3220 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3222 return gen_rtx_AND (0, op0, op1);
3225 op0 = elim_reg_cond (XEXP (x, 0), regno);
3226 op1 = elim_reg_cond (XEXP (x, 1), regno);
3227 if (op0 == const1_rtx || op1 == const1_rtx)
3229 if (op0 == const0_rtx)
3231 if (op1 == const0_rtx)
3233 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3235 return gen_rtx_IOR (0, op0, op1);
3238 op0 = elim_reg_cond (XEXP (x, 0), regno);
3239 if (op0 == const0_rtx)
3241 if (op0 == const1_rtx)
3243 if (op0 != XEXP (x, 0))
3244 return not_reg_cond (op0);
3251 #endif /* HAVE_conditional_execution */
3255 /* Try to substitute the auto-inc expression INC as the address inside
3256 MEM which occurs in INSN. Currently, the address of MEM is an expression
3257 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3258 that has a single set whose source is a PLUS of INCR_REG and something
3262 attempt_auto_inc (struct propagate_block_info *pbi, rtx inc, rtx insn,
3263 rtx mem, rtx incr, rtx incr_reg)
3265 int regno = REGNO (incr_reg);
3266 rtx set = single_set (incr);
3267 rtx q = SET_DEST (set);
3268 rtx y = SET_SRC (set);
3269 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
3272 /* Make sure this reg appears only once in this insn. */
3273 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
3276 if (dead_or_set_p (incr, incr_reg)
3277 /* Mustn't autoinc an eliminable register. */
3278 && (regno >= FIRST_PSEUDO_REGISTER
3279 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
3281 /* This is the simple case. Try to make the auto-inc. If
3282 we can't, we are done. Otherwise, we will do any
3283 needed updates below. */
3284 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
3288 /* PREV_INSN used here to check the semi-open interval
3290 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
3291 /* We must also check for sets of q as q may be
3292 a call clobbered hard register and there may
3293 be a call between PREV_INSN (insn) and incr. */
3294 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
3296 /* We have *p followed sometime later by q = p+size.
3297 Both p and q must be live afterward,
3298 and q is not used between INSN and its assignment.
3299 Change it to q = p, ...*q..., q = q+size.
3300 Then fall into the usual case. */
3304 emit_move_insn (q, incr_reg);
3305 insns = get_insns ();
3308 /* If we can't make the auto-inc, or can't make the
3309 replacement into Y, exit. There's no point in making
3310 the change below if we can't do the auto-inc and doing
3311 so is not correct in the pre-inc case. */
3314 validate_change (insn, &XEXP (mem, 0), inc, 1);
3315 validate_change (incr, &XEXP (y, opnum), q, 1);
3316 if (! apply_change_group ())
3319 /* We now know we'll be doing this change, so emit the
3320 new insn(s) and do the updates. */
3321 emit_insn_before (insns, insn);
3323 if (BB_HEAD (pbi->bb) == insn)
3324 BB_HEAD (pbi->bb) = insns;
3326 /* INCR will become a NOTE and INSN won't contain a
3327 use of INCR_REG. If a use of INCR_REG was just placed in
3328 the insn before INSN, make that the next use.
3329 Otherwise, invalidate it. */
3330 if (NONJUMP_INSN_P (PREV_INSN (insn))
3331 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
3332 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
3333 pbi->reg_next_use[regno] = PREV_INSN (insn);
3335 pbi->reg_next_use[regno] = 0;
3340 if ((pbi->flags & PROP_REG_INFO)
3341 && !REGNO_REG_SET_P (pbi->reg_live, regno))
3342 reg_deaths[regno] = pbi->insn_num;
3344 /* REGNO is now used in INCR which is below INSN, but
3345 it previously wasn't live here. If we don't mark
3346 it as live, we'll put a REG_DEAD note for it
3347 on this insn, which is incorrect. */
3348 SET_REGNO_REG_SET (pbi->reg_live, regno);
3350 /* If there are any calls between INSN and INCR, show
3351 that REGNO now crosses them. */
3352 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
3354 REG_N_CALLS_CROSSED (regno)++;
3356 /* Invalidate alias info for Q since we just changed its value. */
3357 clear_reg_alias_info (q);
3362 /* If we haven't returned, it means we were able to make the
3363 auto-inc, so update the status. First, record that this insn
3364 has an implicit side effect. */
3366 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
3368 /* Modify the old increment-insn to simply copy
3369 the already-incremented value of our register. */
3370 changed = validate_change (incr, &SET_SRC (set), incr_reg, 0);
3371 gcc_assert (changed);
3373 /* If that makes it a no-op (copying the register into itself) delete
3374 it so it won't appear to be a "use" and a "set" of this
3376 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
3378 /* If the original source was dead, it's dead now. */
3381 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
3383 remove_note (incr, note);
3384 if (XEXP (note, 0) != incr_reg)
3386 unsigned int regno = REGNO (XEXP (note, 0));
3388 if ((pbi->flags & PROP_REG_INFO)
3389 && REGNO_REG_SET_P (pbi->reg_live, regno))
3391 REG_LIVE_LENGTH (regno) += pbi->insn_num - reg_deaths[regno];
3392 reg_deaths[regno] = 0;
3394 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
3398 SET_INSN_DELETED (incr);
3401 if (regno >= FIRST_PSEUDO_REGISTER)
3403 /* Count an extra reference to the reg. When a reg is
3404 incremented, spilling it is worse, so we want to make
3405 that less likely. */
3406 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3408 /* Count the increment as a setting of the register,
3409 even though it isn't a SET in rtl. */
3410 REG_N_SETS (regno)++;
3414 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3418 find_auto_inc (struct propagate_block_info *pbi, rtx x, rtx insn)
3420 rtx addr = XEXP (x, 0);
3421 HOST_WIDE_INT offset = 0;
3422 rtx set, y, incr, inc_val;
3424 int size = GET_MODE_SIZE (GET_MODE (x));
3429 /* Here we detect use of an index register which might be good for
3430 postincrement, postdecrement, preincrement, or predecrement. */
3432 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
3433 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
3438 regno = REGNO (addr);
3440 /* Is the next use an increment that might make auto-increment? */
3441 incr = pbi->reg_next_use[regno];
3442 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
3444 set = single_set (incr);
3445 if (set == 0 || GET_CODE (set) != SET)
3449 if (GET_CODE (y) != PLUS)
3452 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
3453 inc_val = XEXP (y, 1);
3454 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
3455 inc_val = XEXP (y, 0);
3459 if (GET_CODE (inc_val) == CONST_INT)
3461 if (HAVE_POST_INCREMENT
3462 && (INTVAL (inc_val) == size && offset == 0))
3463 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
3465 else if (HAVE_POST_DECREMENT
3466 && (INTVAL (inc_val) == -size && offset == 0))
3467 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
3469 else if (HAVE_PRE_INCREMENT
3470 && (INTVAL (inc_val) == size && offset == size))
3471 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
3473 else if (HAVE_PRE_DECREMENT
3474 && (INTVAL (inc_val) == -size && offset == -size))
3475 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
3477 else if (HAVE_POST_MODIFY_DISP && offset == 0)
3478 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3479 gen_rtx_PLUS (Pmode,
3482 insn, x, incr, addr);
3483 else if (HAVE_PRE_MODIFY_DISP && offset == INTVAL (inc_val))
3484 attempt_auto_inc (pbi, gen_rtx_PRE_MODIFY (Pmode, addr,
3485 gen_rtx_PLUS (Pmode,
3488 insn, x, incr, addr);
3490 else if (REG_P (inc_val)
3491 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
3495 if (HAVE_POST_MODIFY_REG && offset == 0)
3496 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3497 gen_rtx_PLUS (Pmode,
3500 insn, x, incr, addr);
3504 #endif /* AUTO_INC_DEC */
3507 mark_used_reg (struct propagate_block_info *pbi, rtx reg,
3508 rtx cond ATTRIBUTE_UNUSED, rtx insn)
3510 unsigned int regno_first, regno_last, i;
3511 int some_was_live, some_was_dead, some_not_set;
3513 regno_last = regno_first = REGNO (reg);
3514 if (regno_first < FIRST_PSEUDO_REGISTER)
3515 regno_last += hard_regno_nregs[regno_first][GET_MODE (reg)] - 1;
3517 /* Find out if any of this register is live after this instruction. */
3518 some_was_live = some_was_dead = 0;
3519 for (i = regno_first; i <= regno_last; ++i)
3521 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
3522 some_was_live |= needed_regno;
3523 some_was_dead |= ! needed_regno;
3526 /* Find out if any of the register was set this insn. */
3528 for (i = regno_first; i <= regno_last; ++i)
3529 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
3531 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3533 /* Record where each reg is used, so when the reg is set we know
3534 the next insn that uses it. */
3535 pbi->reg_next_use[regno_first] = insn;
3538 if (pbi->flags & PROP_REG_INFO)
3540 if (regno_first < FIRST_PSEUDO_REGISTER)
3542 /* If this is a register we are going to try to eliminate,
3543 don't mark it live here. If we are successful in
3544 eliminating it, it need not be live unless it is used for
3545 pseudos, in which case it will have been set live when it
3546 was allocated to the pseudos. If the register will not
3547 be eliminated, reload will set it live at that point.
3549 Otherwise, record that this function uses this register. */
3550 /* ??? The PPC backend tries to "eliminate" on the pic
3551 register to itself. This should be fixed. In the mean
3552 time, hack around it. */
3554 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
3555 && (regno_first == FRAME_POINTER_REGNUM
3556 || regno_first == ARG_POINTER_REGNUM)))
3557 for (i = regno_first; i <= regno_last; ++i)
3558 regs_ever_live[i] = 1;
3562 /* Keep track of which basic block each reg appears in. */
3564 int blocknum = pbi->bb->index;
3565 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
3566 REG_BASIC_BLOCK (regno_first) = blocknum;
3567 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
3568 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
3570 /* Count (weighted) number of uses of each reg. */
3571 REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb);
3572 REG_N_REFS (regno_first)++;
3574 for (i = regno_first; i <= regno_last; ++i)
3575 if (! REGNO_REG_SET_P (pbi->reg_live, i))
3577 gcc_assert (!reg_deaths[i]);
3578 reg_deaths[i] = pbi->insn_num;
3582 /* Record and count the insns in which a reg dies. If it is used in
3583 this insn and was dead below the insn then it dies in this insn.
3584 If it was set in this insn, we do not make a REG_DEAD note;
3585 likewise if we already made such a note. */
3586 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
3590 /* Check for the case where the register dying partially
3591 overlaps the register set by this insn. */
3592 if (regno_first != regno_last)
3593 for (i = regno_first; i <= regno_last; ++i)
3594 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
3596 /* If none of the words in X is needed, make a REG_DEAD note.
3597 Otherwise, we must make partial REG_DEAD notes. */
3598 if (! some_was_live)
3600 if ((pbi->flags & PROP_DEATH_NOTES)
3601 && ! find_regno_note (insn, REG_DEAD, regno_first))
3603 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
3605 if (pbi->flags & PROP_REG_INFO)
3606 REG_N_DEATHS (regno_first)++;
3610 /* Don't make a REG_DEAD note for a part of a register
3611 that is set in the insn. */
3612 for (i = regno_first; i <= regno_last; ++i)
3613 if (! REGNO_REG_SET_P (pbi->reg_live, i)
3614 && ! dead_or_set_regno_p (insn, i))
3616 = alloc_EXPR_LIST (REG_DEAD,
3622 /* Mark the register as being live. */
3623 for (i = regno_first; i <= regno_last; ++i)
3625 #ifdef HAVE_conditional_execution
3626 int this_was_live = REGNO_REG_SET_P (pbi->reg_live, i);
3629 SET_REGNO_REG_SET (pbi->reg_live, i);
3631 #ifdef HAVE_conditional_execution
3632 /* If this is a conditional use, record that fact. If it is later
3633 conditionally set, we'll know to kill the register. */
3634 if (cond != NULL_RTX)
3636 splay_tree_node node;
3637 struct reg_cond_life_info *rcli;
3642 node = splay_tree_lookup (pbi->reg_cond_dead, i);
3645 /* The register was unconditionally live previously.
3646 No need to do anything. */
3650 /* The register was conditionally live previously.
3651 Subtract the new life cond from the old death cond. */
3652 rcli = (struct reg_cond_life_info *) node->value;
3653 ncond = rcli->condition;
3654 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
3656 /* If the register is now unconditionally live,
3657 remove the entry in the splay_tree. */
3658 if (ncond == const0_rtx)
3659 splay_tree_remove (pbi->reg_cond_dead, i);
3662 rcli->condition = ncond;
3663 SET_REGNO_REG_SET (pbi->reg_cond_reg,
3664 REGNO (XEXP (cond, 0)));
3670 /* The register was not previously live at all. Record
3671 the condition under which it is still dead. */
3672 rcli = xmalloc (sizeof (*rcli));
3673 rcli->condition = not_reg_cond (cond);
3674 rcli->stores = const0_rtx;
3675 rcli->orig_condition = const0_rtx;
3676 splay_tree_insert (pbi->reg_cond_dead, i,
3677 (splay_tree_value) rcli);
3679 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
3682 else if (this_was_live)
3684 /* The register may have been conditionally live previously, but
3685 is now unconditionally live. Remove it from the conditionally
3686 dead list, so that a conditional set won't cause us to think
3688 splay_tree_remove (pbi->reg_cond_dead, i);
3694 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3695 This is done assuming the registers needed from X are those that
3696 have 1-bits in PBI->REG_LIVE.
3698 INSN is the containing instruction. If INSN is dead, this function
3702 mark_used_regs (struct propagate_block_info *pbi, rtx x, rtx cond, rtx insn)
3706 int flags = pbi->flags;
3711 code = GET_CODE (x);
3732 /* If we are clobbering a MEM, mark any registers inside the address
3734 if (MEM_P (XEXP (x, 0)))
3735 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
3739 /* Don't bother watching stores to mems if this is not the
3740 final pass. We'll not be deleting dead stores this round. */
3741 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
3743 /* Invalidate the data for the last MEM stored, but only if MEM is
3744 something that can be stored into. */
3745 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3746 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3747 /* Needn't clear the memory set list. */
3751 rtx temp = pbi->mem_set_list;
3752 rtx prev = NULL_RTX;
3757 next = XEXP (temp, 1);
3758 if (anti_dependence (XEXP (temp, 0), x))
3760 /* Splice temp out of the list. */
3762 XEXP (prev, 1) = next;
3764 pbi->mem_set_list = next;
3765 free_EXPR_LIST_node (temp);
3766 pbi->mem_set_list_len--;
3774 /* If the memory reference had embedded side effects (autoincrement
3775 address modes. Then we may need to kill some entries on the
3778 for_each_rtx (&PATTERN (insn), invalidate_mems_from_autoinc, pbi);
3782 if (flags & PROP_AUTOINC)
3783 find_auto_inc (pbi, x, insn);
3788 #ifdef CANNOT_CHANGE_MODE_CLASS
3789 if (flags & PROP_REG_INFO)
3790 record_subregs_of_mode (x);
3793 /* While we're here, optimize this case. */
3800 /* See a register other than being set => mark it as needed. */
3801 mark_used_reg (pbi, x, cond, insn);
3806 rtx testreg = SET_DEST (x);
3809 /* If storing into MEM, don't show it as being used. But do
3810 show the address as being used. */
3811 if (MEM_P (testreg))
3814 if (flags & PROP_AUTOINC)
3815 find_auto_inc (pbi, testreg, insn);
3817 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
3818 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3822 /* Storing in STRICT_LOW_PART is like storing in a reg
3823 in that this SET might be dead, so ignore it in TESTREG.
3824 but in some other ways it is like using the reg.
3826 Storing in a SUBREG or a bit field is like storing the entire
3827 register in that if the register's value is not used
3828 then this SET is not needed. */
3829 while (GET_CODE (testreg) == STRICT_LOW_PART
3830 || GET_CODE (testreg) == ZERO_EXTRACT
3831 || GET_CODE (testreg) == SIGN_EXTRACT
3832 || GET_CODE (testreg) == SUBREG)
3834 #ifdef CANNOT_CHANGE_MODE_CLASS
3835 if ((flags & PROP_REG_INFO) && GET_CODE (testreg) == SUBREG)
3836 record_subregs_of_mode (testreg);
3839 /* Modifying a single register in an alternate mode
3840 does not use any of the old value. But these other
3841 ways of storing in a register do use the old value. */
3842 if (GET_CODE (testreg) == SUBREG
3843 && !((REG_BYTES (SUBREG_REG (testreg))
3844 + UNITS_PER_WORD - 1) / UNITS_PER_WORD
3845 > (REG_BYTES (testreg)
3846 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
3851 testreg = XEXP (testreg, 0);
3854 /* If this is a store into a register or group of registers,
3855 recursively scan the value being stored. */
3857 if ((GET_CODE (testreg) == PARALLEL
3858 && GET_MODE (testreg) == BLKmode)
3860 && (regno = REGNO (testreg),
3861 ! (regno == FRAME_POINTER_REGNUM
3862 && (! reload_completed || frame_pointer_needed)))
3863 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3864 && ! (regno == HARD_FRAME_POINTER_REGNUM
3865 && (! reload_completed || frame_pointer_needed))
3867 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3868 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
3873 mark_used_regs (pbi, SET_DEST (x), cond, insn);
3874 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3881 case UNSPEC_VOLATILE:
3885 /* Traditional and volatile asm instructions must be considered to use
3886 and clobber all hard registers, all pseudo-registers and all of
3887 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3889 Consider for instance a volatile asm that changes the fpu rounding
3890 mode. An insn should not be moved across this even if it only uses
3891 pseudo-regs because it might give an incorrectly rounded result.
3893 ?!? Unfortunately, marking all hard registers as live causes massive
3894 problems for the register allocator and marking all pseudos as live
3895 creates mountains of uninitialized variable warnings.
3897 So for now, just clear the memory set list and mark any regs
3898 we can find in ASM_OPERANDS as used. */
3899 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
3901 free_EXPR_LIST_list (&pbi->mem_set_list);
3902 pbi->mem_set_list_len = 0;
3905 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3906 We can not just fall through here since then we would be confused
3907 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3908 traditional asms unlike their normal usage. */
3909 if (code == ASM_OPERANDS)
3913 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
3914 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
3922 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
3924 cond = COND_EXEC_TEST (x);
3925 x = COND_EXEC_CODE (x);
3932 /* Recursively scan the operands of this expression. */
3935 const char * const fmt = GET_RTX_FORMAT (code);
3938 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3942 /* Tail recursive case: save a function call level. */
3948 mark_used_regs (pbi, XEXP (x, i), cond, insn);
3950 else if (fmt[i] == 'E')
3953 for (j = 0; j < XVECLEN (x, i); j++)
3954 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
3963 try_pre_increment_1 (struct propagate_block_info *pbi, rtx insn)
3965 /* Find the next use of this reg. If in same basic block,
3966 make it do pre-increment or pre-decrement if appropriate. */
3967 rtx x = single_set (insn);
3968 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
3969 * INTVAL (XEXP (SET_SRC (x), 1)));
3970 int regno = REGNO (SET_DEST (x));
3971 rtx y = pbi->reg_next_use[regno];
3973 && SET_DEST (x) != stack_pointer_rtx
3974 && BLOCK_NUM (y) == BLOCK_NUM (insn)
3975 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3976 mode would be better. */
3977 && ! dead_or_set_p (y, SET_DEST (x))
3978 && try_pre_increment (y, SET_DEST (x), amount))
3980 /* We have found a suitable auto-increment and already changed
3981 insn Y to do it. So flush this increment instruction. */
3982 propagate_block_delete_insn (insn);
3984 /* Count a reference to this reg for the increment insn we are
3985 deleting. When a reg is incremented, spilling it is worse,
3986 so we want to make that less likely. */
3987 if (regno >= FIRST_PSEUDO_REGISTER)
3989 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3990 REG_N_SETS (regno)++;
3993 /* Flush any remembered memories depending on the value of
3994 the incremented register. */
3995 invalidate_mems_from_set (pbi, SET_DEST (x));
4002 /* Try to change INSN so that it does pre-increment or pre-decrement
4003 addressing on register REG in order to add AMOUNT to REG.
4004 AMOUNT is negative for pre-decrement.
4005 Returns 1 if the change could be made.
4006 This checks all about the validity of the result of modifying INSN. */
4009 try_pre_increment (rtx insn, rtx reg, HOST_WIDE_INT amount)
4013 /* Nonzero if we can try to make a pre-increment or pre-decrement.
4014 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
4016 /* Nonzero if we can try to make a post-increment or post-decrement.
4017 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
4018 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
4019 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
4022 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
4025 /* From the sign of increment, see which possibilities are conceivable
4026 on this target machine. */
4027 if (HAVE_PRE_INCREMENT && amount > 0)
4029 if (HAVE_POST_INCREMENT && amount > 0)
4032 if (HAVE_PRE_DECREMENT && amount < 0)
4034 if (HAVE_POST_DECREMENT && amount < 0)
4037 if (! (pre_ok || post_ok))
4040 /* It is not safe to add a side effect to a jump insn
4041 because if the incremented register is spilled and must be reloaded
4042 there would be no way to store the incremented value back in memory. */
4049 use = find_use_as_address (PATTERN (insn), reg, 0);
4050 if (post_ok && (use == 0 || use == (rtx) (size_t) 1))
4052 use = find_use_as_address (PATTERN (insn), reg, -amount);
4056 if (use == 0 || use == (rtx) (size_t) 1)
4059 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
4062 /* See if this combination of instruction and addressing mode exists. */
4063 if (! validate_change (insn, &XEXP (use, 0),
4064 gen_rtx_fmt_e (amount > 0
4065 ? (do_post ? POST_INC : PRE_INC)
4066 : (do_post ? POST_DEC : PRE_DEC),
4070 /* Record that this insn now has an implicit side effect on X. */
4071 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
4075 #endif /* AUTO_INC_DEC */
4077 /* Find the place in the rtx X where REG is used as a memory address.
4078 Return the MEM rtx that so uses it.
4079 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4080 (plus REG (const_int PLUSCONST)).
4082 If such an address does not appear, return 0.
4083 If REG appears more than once, or is used other than in such an address,
4087 find_use_as_address (rtx x, rtx reg, HOST_WIDE_INT plusconst)
4089 enum rtx_code code = GET_CODE (x);
4090 const char * const fmt = GET_RTX_FORMAT (code);
4095 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
4098 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
4099 && XEXP (XEXP (x, 0), 0) == reg
4100 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
4101 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
4104 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
4106 /* If REG occurs inside a MEM used in a bit-field reference,
4107 that is unacceptable. */
4108 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
4109 return (rtx) (size_t) 1;
4113 return (rtx) (size_t) 1;
4115 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4119 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
4123 return (rtx) (size_t) 1;
4125 else if (fmt[i] == 'E')
4128 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4130 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
4134 return (rtx) (size_t) 1;
4142 /* Write information about registers and basic blocks into FILE.
4143 This is part of making a debugging dump. */
4146 dump_regset (regset r, FILE *outf)
4149 reg_set_iterator rsi;
4153 fputs (" (nil)", outf);
4157 EXECUTE_IF_SET_IN_REG_SET (r, 0, i, rsi)
4159 fprintf (outf, " %d", i);
4160 if (i < FIRST_PSEUDO_REGISTER)
4161 fprintf (outf, " [%s]",
4166 /* Print a human-readable representation of R on the standard error
4167 stream. This function is designed to be used from within the
4171 debug_regset (regset r)
4173 dump_regset (r, stderr);
4174 putc ('\n', stderr);
4177 /* Recompute register set/reference counts immediately prior to register
4180 This avoids problems with set/reference counts changing to/from values
4181 which have special meanings to the register allocators.
4183 Additionally, the reference counts are the primary component used by the
4184 register allocators to prioritize pseudos for allocation to hard regs.
4185 More accurate reference counts generally lead to better register allocation.
4187 F is the first insn to be scanned.
4189 LOOP_STEP denotes how much loop_depth should be incremented per
4190 loop nesting level in order to increase the ref count more for
4191 references in a loop.
4193 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4194 possibly other information which is used by the register allocators. */
4197 recompute_reg_usage (rtx f ATTRIBUTE_UNUSED, int loop_step ATTRIBUTE_UNUSED)
4199 allocate_reg_life_data ();
4200 /* distribute_notes in combiner fails to convert some of the REG_UNUSED notes
4201 to REG_DEAD notes. This causes CHECK_DEAD_NOTES in sched1 to abort. To
4202 solve this update the DEATH_NOTES here. */
4203 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO | PROP_DEATH_NOTES);
4206 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4207 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4208 of the number of registers that died. */
4211 count_or_remove_death_notes (sbitmap blocks, int kill)
4217 /* This used to be a loop over all the blocks with a membership test
4218 inside the loop. That can be amazingly expensive on a large CFG
4219 when only a small number of bits are set in BLOCKs (for example,
4220 the calls from the scheduler typically have very few bits set).
4222 For extra credit, someone should convert BLOCKS to a bitmap rather
4226 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4228 count += count_or_remove_death_notes_bb (BASIC_BLOCK (i), kill);
4235 count += count_or_remove_death_notes_bb (bb, kill);
4242 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from basic
4243 block BB. Returns a count of the number of registers that died. */
4246 count_or_remove_death_notes_bb (basic_block bb, int kill)
4251 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
4255 rtx *pprev = ®_NOTES (insn);
4260 switch (REG_NOTE_KIND (link))
4263 if (REG_P (XEXP (link, 0)))
4265 rtx reg = XEXP (link, 0);
4268 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
4271 n = hard_regno_nregs[REGNO (reg)][GET_MODE (reg)];
4280 rtx next = XEXP (link, 1);
4281 free_EXPR_LIST_node (link);
4282 *pprev = link = next;
4288 pprev = &XEXP (link, 1);
4295 if (insn == BB_END (bb))
4302 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4303 if blocks is NULL. */
4306 clear_log_links (sbitmap blocks)
4313 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4315 free_INSN_LIST_list (&LOG_LINKS (insn));
4318 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4320 basic_block bb = BASIC_BLOCK (i);
4322 for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
4323 insn = NEXT_INSN (insn))
4325 free_INSN_LIST_list (&LOG_LINKS (insn));
4329 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4330 correspond to the hard registers, if any, set in that map. This
4331 could be done far more efficiently by having all sorts of special-cases
4332 with moving single words, but probably isn't worth the trouble. */
4335 reg_set_to_hard_reg_set (HARD_REG_SET *to, bitmap from)
4340 EXECUTE_IF_SET_IN_BITMAP (from, 0, i, bi)
4342 if (i >= FIRST_PSEUDO_REGISTER)
4344 SET_HARD_REG_BIT (*to, i);