* c-tree.h, combine.c, expmed.c, flow.c, libgcc2.c,
[official-gcc.git] / gcc / flow.c
blob1ab2a94567f8d330ff5264d06579f391b7f905a1
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, 2005 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
10 version.
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
15 for more details.
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
20 02111-1307, USA. */
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.
43 ** life_analysis **
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
75 REG_DEAD notes.
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
94 that is never used.
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. */
112 /* TODO:
114 Split out from life_analysis:
115 - local property discovery
116 - global property computation
117 - log links creation
118 - pre/post modify transformation
121 #include "config.h"
122 #include "system.h"
123 #include "coretypes.h"
124 #include "tm.h"
125 #include "tree.h"
126 #include "rtl.h"
127 #include "tm_p.h"
128 #include "hard-reg-set.h"
129 #include "basic-block.h"
130 #include "insn-config.h"
131 #include "regs.h"
132 #include "flags.h"
133 #include "output.h"
134 #include "function.h"
135 #include "except.h"
136 #include "toplev.h"
137 #include "recog.h"
138 #include "expr.h"
139 #include "timevar.h"
141 #include "obstack.h"
142 #include "splay-tree.h"
144 #ifndef HAVE_epilogue
145 #define HAVE_epilogue 0
146 #endif
147 #ifndef HAVE_prologue
148 #define HAVE_prologue 0
149 #endif
150 #ifndef HAVE_sibcall_epilogue
151 #define HAVE_sibcall_epilogue 0
152 #endif
154 #ifndef EPILOGUE_USES
155 #define EPILOGUE_USES(REGNO) 0
156 #endif
157 #ifndef EH_USES
158 #define EH_USES(REGNO) 0
159 #endif
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))
165 #endif
166 #endif
168 /* Nonzero if the second flow pass has completed. */
169 int flow2_completed;
171 /* Maximum register number used in this function, plus one. */
173 int max_regno;
175 /* Indexed by n, giving various register information */
177 varray_type reg_n_info;
179 /* Regset of regs live when calls to `setjmp'-like functions happen. */
180 /* ??? Does this exist only for the setjmp-clobbered warning message? */
182 regset regs_live_at_setjmp;
184 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
185 that have to go in the same hard reg.
186 The first two regs in the list are a pair, and the next two
187 are another pair, etc. */
188 rtx regs_may_share;
190 /* Set of registers that may be eliminable. These are handled specially
191 in updating regs_ever_live. */
193 static HARD_REG_SET elim_reg_set;
195 /* Holds information for tracking conditional register life information. */
196 struct reg_cond_life_info
198 /* A boolean expression of conditions under which a register is dead. */
199 rtx condition;
200 /* Conditions under which a register is dead at the basic block end. */
201 rtx orig_condition;
203 /* A boolean expression of conditions under which a register has been
204 stored into. */
205 rtx stores;
207 /* ??? Could store mask of bytes that are dead, so that we could finally
208 track lifetimes of multi-word registers accessed via subregs. */
211 /* For use in communicating between propagate_block and its subroutines.
212 Holds all information needed to compute life and def-use information. */
214 struct propagate_block_info
216 /* The basic block we're considering. */
217 basic_block bb;
219 /* Bit N is set if register N is conditionally or unconditionally live. */
220 regset reg_live;
222 /* Bit N is set if register N is set this insn. */
223 regset new_set;
225 /* Element N is the next insn that uses (hard or pseudo) register N
226 within the current basic block; or zero, if there is no such insn. */
227 rtx *reg_next_use;
229 /* Contains a list of all the MEMs we are tracking for dead store
230 elimination. */
231 rtx mem_set_list;
233 /* If non-null, record the set of registers set unconditionally in the
234 basic block. */
235 regset local_set;
237 /* If non-null, record the set of registers set conditionally in the
238 basic block. */
239 regset cond_local_set;
241 #ifdef HAVE_conditional_execution
242 /* Indexed by register number, holds a reg_cond_life_info for each
243 register that is not unconditionally live or dead. */
244 splay_tree reg_cond_dead;
246 /* Bit N is set if register N is in an expression in reg_cond_dead. */
247 regset reg_cond_reg;
248 #endif
250 /* The length of mem_set_list. */
251 int mem_set_list_len;
253 /* Nonzero if the value of CC0 is live. */
254 int cc0_live;
256 /* Flags controlling the set of information propagate_block collects. */
257 int flags;
258 /* Index of instruction being processed. */
259 int insn_num;
262 /* Number of dead insns removed. */
263 static int ndead;
265 /* When PROP_REG_INFO set, array contains pbi->insn_num of instruction
266 where given register died. When the register is marked alive, we use the
267 information to compute amount of instructions life range cross.
268 (remember, we are walking backward). This can be computed as current
269 pbi->insn_num - reg_deaths[regno].
270 At the end of processing each basic block, the remaining live registers
271 are inspected and liferanges are increased same way so liverange of global
272 registers are computed correctly.
274 The array is maintained clear for dead registers, so it can be safely reused
275 for next basic block without expensive memset of the whole array after
276 reseting pbi->insn_num to 0. */
278 static int *reg_deaths;
280 /* Maximum length of pbi->mem_set_list before we start dropping
281 new elements on the floor. */
282 #define MAX_MEM_SET_LIST_LEN 100
284 /* Forward declarations */
285 static int verify_wide_reg_1 (rtx *, void *);
286 static void verify_wide_reg (int, basic_block);
287 static void verify_local_live_at_start (regset, basic_block);
288 static void notice_stack_pointer_modification_1 (rtx, rtx, void *);
289 static void notice_stack_pointer_modification (void);
290 static void mark_reg (rtx, void *);
291 static void mark_regs_live_at_end (regset);
292 static void calculate_global_regs_live (sbitmap, sbitmap, int);
293 static void propagate_block_delete_insn (rtx);
294 static rtx propagate_block_delete_libcall (rtx, rtx);
295 static int insn_dead_p (struct propagate_block_info *, rtx, int, rtx);
296 static int libcall_dead_p (struct propagate_block_info *, rtx, rtx);
297 static void mark_set_regs (struct propagate_block_info *, rtx, rtx);
298 static void mark_set_1 (struct propagate_block_info *, enum rtx_code, rtx,
299 rtx, rtx, int);
300 static int find_regno_partial (rtx *, void *);
302 #ifdef HAVE_conditional_execution
303 static int mark_regno_cond_dead (struct propagate_block_info *, int, rtx);
304 static void free_reg_cond_life_info (splay_tree_value);
305 static int flush_reg_cond_reg_1 (splay_tree_node, void *);
306 static void flush_reg_cond_reg (struct propagate_block_info *, int);
307 static rtx elim_reg_cond (rtx, unsigned int);
308 static rtx ior_reg_cond (rtx, rtx, int);
309 static rtx not_reg_cond (rtx);
310 static rtx and_reg_cond (rtx, rtx, int);
311 #endif
312 #ifdef AUTO_INC_DEC
313 static void attempt_auto_inc (struct propagate_block_info *, rtx, rtx, rtx,
314 rtx, rtx);
315 static void find_auto_inc (struct propagate_block_info *, rtx, rtx);
316 static int try_pre_increment_1 (struct propagate_block_info *, rtx);
317 static int try_pre_increment (rtx, rtx, HOST_WIDE_INT);
318 #endif
319 static void mark_used_reg (struct propagate_block_info *, rtx, rtx, rtx);
320 static void mark_used_regs (struct propagate_block_info *, rtx, rtx, rtx);
321 void debug_flow_info (void);
322 static void add_to_mem_set_list (struct propagate_block_info *, rtx);
323 static int invalidate_mems_from_autoinc (rtx *, void *);
324 static void invalidate_mems_from_set (struct propagate_block_info *, rtx);
325 static void clear_log_links (sbitmap);
326 static int count_or_remove_death_notes_bb (basic_block, int);
327 static void allocate_bb_life_data (void);
329 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
330 note associated with the BLOCK. */
333 first_insn_after_basic_block_note (basic_block block)
335 rtx insn;
337 /* Get the first instruction in the block. */
338 insn = BB_HEAD (block);
340 if (insn == NULL_RTX)
341 return NULL_RTX;
342 if (LABEL_P (insn))
343 insn = NEXT_INSN (insn);
344 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
346 return NEXT_INSN (insn);
349 /* Perform data flow analysis for the whole control flow graph.
350 FLAGS is a set of PROP_* flags to be used in accumulating flow info. */
352 void
353 life_analysis (FILE *file, int flags)
355 #ifdef ELIMINABLE_REGS
356 int i;
357 static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS;
358 #endif
360 /* Record which registers will be eliminated. We use this in
361 mark_used_regs. */
363 CLEAR_HARD_REG_SET (elim_reg_set);
365 #ifdef ELIMINABLE_REGS
366 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
367 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
368 #else
369 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
370 #endif
373 #ifdef CANNOT_CHANGE_MODE_CLASS
374 if (flags & PROP_REG_INFO)
375 init_subregs_of_mode ();
376 #endif
378 if (! optimize)
379 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES);
381 /* The post-reload life analysis have (on a global basis) the same
382 registers live as was computed by reload itself. elimination
383 Otherwise offsets and such may be incorrect.
385 Reload will make some registers as live even though they do not
386 appear in the rtl.
388 We don't want to create new auto-incs after reload, since they
389 are unlikely to be useful and can cause problems with shared
390 stack slots. */
391 if (reload_completed)
392 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
394 /* We want alias analysis information for local dead store elimination. */
395 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
396 init_alias_analysis ();
398 /* Always remove no-op moves. Do this before other processing so
399 that we don't have to keep re-scanning them. */
400 delete_noop_moves ();
402 /* Some targets can emit simpler epilogues if they know that sp was
403 not ever modified during the function. After reload, of course,
404 we've already emitted the epilogue so there's no sense searching. */
405 if (! reload_completed)
406 notice_stack_pointer_modification ();
408 /* Allocate and zero out data structures that will record the
409 data from lifetime analysis. */
410 allocate_reg_life_data ();
411 allocate_bb_life_data ();
413 /* Find the set of registers live on function exit. */
414 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
416 /* "Update" life info from zero. It'd be nice to begin the
417 relaxation with just the exit and noreturn blocks, but that set
418 is not immediately handy. */
420 if (flags & PROP_REG_INFO)
422 memset (regs_ever_live, 0, sizeof (regs_ever_live));
423 memset (regs_asm_clobbered, 0, sizeof (regs_asm_clobbered));
425 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
426 if (reg_deaths)
428 free (reg_deaths);
429 reg_deaths = NULL;
432 /* Clean up. */
433 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
434 end_alias_analysis ();
436 if (file)
437 dump_flow_info (file);
439 /* Removing dead insns should have made jumptables really dead. */
440 delete_dead_jumptables ();
443 /* A subroutine of verify_wide_reg, called through for_each_rtx.
444 Search for REGNO. If found, return 2 if it is not wider than
445 word_mode. */
447 static int
448 verify_wide_reg_1 (rtx *px, void *pregno)
450 rtx x = *px;
451 unsigned int regno = *(int *) pregno;
453 if (REG_P (x) && REGNO (x) == regno)
455 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
456 return 2;
457 return 1;
459 return 0;
462 /* A subroutine of verify_local_live_at_start. Search through insns
463 of BB looking for register REGNO. */
465 static void
466 verify_wide_reg (int regno, basic_block bb)
468 rtx head = BB_HEAD (bb), end = BB_END (bb);
470 while (1)
472 if (INSN_P (head))
474 int r = for_each_rtx (&PATTERN (head), verify_wide_reg_1, &regno);
475 if (r == 1)
476 return;
477 if (r == 2)
478 break;
480 if (head == end)
481 break;
482 head = NEXT_INSN (head);
484 if (dump_file)
486 fprintf (dump_file, "Register %d died unexpectedly.\n", regno);
487 dump_bb (bb, dump_file, 0);
489 fatal_error ("internal consistency failure");
492 /* A subroutine of update_life_info. Verify that there are no untoward
493 changes in live_at_start during a local update. */
495 static void
496 verify_local_live_at_start (regset new_live_at_start, basic_block bb)
498 if (reload_completed)
500 /* After reload, there are no pseudos, nor subregs of multi-word
501 registers. The regsets should exactly match. */
502 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
504 if (dump_file)
506 fprintf (dump_file,
507 "live_at_start mismatch in bb %d, aborting\nNew:\n",
508 bb->index);
509 debug_bitmap_file (dump_file, new_live_at_start);
510 fputs ("Old:\n", dump_file);
511 dump_bb (bb, dump_file, 0);
513 fatal_error ("internal consistency failure");
516 else
518 unsigned i;
519 reg_set_iterator rsi;
521 /* Find the set of changed registers. */
522 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
524 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i, rsi)
526 /* No registers should die. */
527 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
529 if (dump_file)
531 fprintf (dump_file,
532 "Register %d died unexpectedly.\n", i);
533 dump_bb (bb, dump_file, 0);
535 fatal_error ("internal consistency failure");
537 /* Verify that the now-live register is wider than word_mode. */
538 verify_wide_reg (i, bb);
543 /* Updates life information starting with the basic blocks set in BLOCKS.
544 If BLOCKS is null, consider it to be the universal set.
546 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholing,
547 we are only expecting local modifications to basic blocks. If we find
548 extra registers live at the beginning of a block, then we either killed
549 useful data, or we have a broken split that wants data not provided.
550 If we find registers removed from live_at_start, that means we have
551 a broken peephole that is killing a register it shouldn't.
553 ??? This is not true in one situation -- when a pre-reload splitter
554 generates subregs of a multi-word pseudo, current life analysis will
555 lose the kill. So we _can_ have a pseudo go live. How irritating.
557 It is also not true when a peephole decides that it doesn't need one
558 or more of the inputs.
560 Including PROP_REG_INFO does not properly refresh regs_ever_live
561 unless the caller resets it to zero. */
564 update_life_info (sbitmap blocks, enum update_life_extent extent,
565 int prop_flags)
567 regset tmp;
568 unsigned i;
569 int stabilized_prop_flags = prop_flags;
570 basic_block bb;
572 tmp = ALLOC_REG_SET (&reg_obstack);
573 ndead = 0;
575 if ((prop_flags & PROP_REG_INFO) && !reg_deaths)
576 reg_deaths = xcalloc (sizeof (*reg_deaths), max_regno);
578 timevar_push ((extent == UPDATE_LIFE_LOCAL || blocks)
579 ? TV_LIFE_UPDATE : TV_LIFE);
581 /* Changes to the CFG are only allowed when
582 doing a global update for the entire CFG. */
583 gcc_assert (!(prop_flags & PROP_ALLOW_CFG_CHANGES)
584 || (extent != UPDATE_LIFE_LOCAL && !blocks));
586 /* For a global update, we go through the relaxation process again. */
587 if (extent != UPDATE_LIFE_LOCAL)
589 for ( ; ; )
591 int changed = 0;
593 calculate_global_regs_live (blocks, blocks,
594 prop_flags & (PROP_SCAN_DEAD_CODE
595 | PROP_SCAN_DEAD_STORES
596 | PROP_ALLOW_CFG_CHANGES));
598 if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
599 != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
600 break;
602 /* Removing dead code may allow the CFG to be simplified which
603 in turn may allow for further dead code detection / removal. */
604 FOR_EACH_BB_REVERSE (bb)
606 COPY_REG_SET (tmp, bb->global_live_at_end);
607 changed |= propagate_block (bb, tmp, NULL, NULL,
608 prop_flags & (PROP_SCAN_DEAD_CODE
609 | PROP_SCAN_DEAD_STORES
610 | PROP_KILL_DEAD_CODE));
613 /* Don't pass PROP_SCAN_DEAD_CODE or PROP_KILL_DEAD_CODE to
614 subsequent propagate_block calls, since removing or acting as
615 removing dead code can affect global register liveness, which
616 is supposed to be finalized for this call after this loop. */
617 stabilized_prop_flags
618 &= ~(PROP_SCAN_DEAD_CODE | PROP_SCAN_DEAD_STORES
619 | PROP_KILL_DEAD_CODE);
621 if (! changed)
622 break;
624 /* We repeat regardless of what cleanup_cfg says. If there were
625 instructions deleted above, that might have been only a
626 partial improvement (see MAX_MEM_SET_LIST_LEN usage).
627 Further improvement may be possible. */
628 cleanup_cfg (CLEANUP_EXPENSIVE);
630 /* Zap the life information from the last round. If we don't
631 do this, we can wind up with registers that no longer appear
632 in the code being marked live at entry. */
633 FOR_EACH_BB (bb)
635 CLEAR_REG_SET (bb->global_live_at_start);
636 CLEAR_REG_SET (bb->global_live_at_end);
640 /* If asked, remove notes from the blocks we'll update. */
641 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
642 count_or_remove_death_notes (blocks, 1);
645 /* Clear log links in case we are asked to (re)compute them. */
646 if (prop_flags & PROP_LOG_LINKS)
647 clear_log_links (blocks);
649 if (blocks)
651 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
653 bb = BASIC_BLOCK (i);
655 COPY_REG_SET (tmp, bb->global_live_at_end);
656 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags);
658 if (extent == UPDATE_LIFE_LOCAL)
659 verify_local_live_at_start (tmp, bb);
662 else
664 FOR_EACH_BB_REVERSE (bb)
666 COPY_REG_SET (tmp, bb->global_live_at_end);
668 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags);
670 if (extent == UPDATE_LIFE_LOCAL)
671 verify_local_live_at_start (tmp, bb);
675 FREE_REG_SET (tmp);
677 if (prop_flags & PROP_REG_INFO)
679 reg_set_iterator rsi;
681 /* The only pseudos that are live at the beginning of the function
682 are those that were not set anywhere in the function. local-alloc
683 doesn't know how to handle these correctly, so mark them as not
684 local to any one basic block. */
685 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
686 FIRST_PSEUDO_REGISTER, i, rsi)
687 REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL;
689 /* We have a problem with any pseudoreg that lives across the setjmp.
690 ANSI says that if a user variable does not change in value between
691 the setjmp and the longjmp, then the longjmp preserves it. This
692 includes longjmp from a place where the pseudo appears dead.
693 (In principle, the value still exists if it is in scope.)
694 If the pseudo goes in a hard reg, some other value may occupy
695 that hard reg where this pseudo is dead, thus clobbering the pseudo.
696 Conclusion: such a pseudo must not go in a hard reg. */
697 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
698 FIRST_PSEUDO_REGISTER, i, rsi)
700 if (regno_reg_rtx[i] != 0)
702 REG_LIVE_LENGTH (i) = -1;
703 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
707 if (reg_deaths)
709 free (reg_deaths);
710 reg_deaths = NULL;
712 timevar_pop ((extent == UPDATE_LIFE_LOCAL || blocks)
713 ? TV_LIFE_UPDATE : TV_LIFE);
714 if (ndead && dump_file)
715 fprintf (dump_file, "deleted %i dead insns\n", ndead);
716 return ndead;
719 /* Update life information in all blocks where BB_DIRTY is set. */
722 update_life_info_in_dirty_blocks (enum update_life_extent extent, int prop_flags)
724 sbitmap update_life_blocks = sbitmap_alloc (last_basic_block);
725 int n = 0;
726 basic_block bb;
727 int retval = 0;
729 sbitmap_zero (update_life_blocks);
730 FOR_EACH_BB (bb)
732 if (extent == UPDATE_LIFE_LOCAL)
734 if (bb->flags & BB_DIRTY)
736 SET_BIT (update_life_blocks, bb->index);
737 n++;
740 else
742 /* ??? Bootstrap with -march=pentium4 fails to terminate
743 with only a partial life update. */
744 SET_BIT (update_life_blocks, bb->index);
745 if (bb->flags & BB_DIRTY)
746 n++;
750 if (n)
751 retval = update_life_info (update_life_blocks, extent, prop_flags);
753 sbitmap_free (update_life_blocks);
754 return retval;
757 /* Free the variables allocated by find_basic_blocks. */
759 void
760 free_basic_block_vars (void)
762 if (basic_block_info)
764 clear_edges ();
765 basic_block_info = NULL;
767 n_basic_blocks = 0;
768 last_basic_block = 0;
770 ENTRY_BLOCK_PTR->aux = NULL;
771 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
772 EXIT_BLOCK_PTR->aux = NULL;
773 EXIT_BLOCK_PTR->global_live_at_start = NULL;
776 /* Delete any insns that copy a register to itself. */
779 delete_noop_moves (void)
781 rtx insn, next;
782 basic_block bb;
783 int nnoops = 0;
785 FOR_EACH_BB (bb)
787 for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb)); insn = next)
789 next = NEXT_INSN (insn);
790 if (INSN_P (insn) && noop_move_p (insn))
792 rtx note;
794 /* If we're about to remove the first insn of a libcall
795 then move the libcall note to the next real insn and
796 update the retval note. */
797 if ((note = find_reg_note (insn, REG_LIBCALL, NULL_RTX))
798 && XEXP (note, 0) != insn)
800 rtx new_libcall_insn = next_real_insn (insn);
801 rtx retval_note = find_reg_note (XEXP (note, 0),
802 REG_RETVAL, NULL_RTX);
803 REG_NOTES (new_libcall_insn)
804 = gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0),
805 REG_NOTES (new_libcall_insn));
806 XEXP (retval_note, 0) = new_libcall_insn;
809 delete_insn_and_edges (insn);
810 nnoops++;
814 if (nnoops && dump_file)
815 fprintf (dump_file, "deleted %i noop moves", nnoops);
816 return nnoops;
819 /* Delete any jump tables never referenced. We can't delete them at the
820 time of removing tablejump insn as they are referenced by the preceding
821 insns computing the destination, so we delay deleting and garbagecollect
822 them once life information is computed. */
823 void
824 delete_dead_jumptables (void)
826 rtx insn, next;
827 for (insn = get_insns (); insn; insn = next)
829 next = NEXT_INSN (insn);
830 if (LABEL_P (insn)
831 && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
832 && JUMP_P (next)
833 && (GET_CODE (PATTERN (next)) == ADDR_VEC
834 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
836 if (dump_file)
837 fprintf (dump_file, "Dead jumptable %i removed\n", INSN_UID (insn));
838 delete_insn (NEXT_INSN (insn));
839 delete_insn (insn);
840 next = NEXT_INSN (next);
845 /* Determine if the stack pointer is constant over the life of the function.
846 Only useful before prologues have been emitted. */
848 static void
849 notice_stack_pointer_modification_1 (rtx x, rtx pat ATTRIBUTE_UNUSED,
850 void *data ATTRIBUTE_UNUSED)
852 if (x == stack_pointer_rtx
853 /* The stack pointer is only modified indirectly as the result
854 of a push until later in flow. See the comments in rtl.texi
855 regarding Embedded Side-Effects on Addresses. */
856 || (MEM_P (x)
857 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == RTX_AUTOINC
858 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
859 current_function_sp_is_unchanging = 0;
862 static void
863 notice_stack_pointer_modification (void)
865 basic_block bb;
866 rtx insn;
868 /* Assume that the stack pointer is unchanging if alloca hasn't
869 been used. */
870 current_function_sp_is_unchanging = !current_function_calls_alloca;
871 if (! current_function_sp_is_unchanging)
872 return;
874 FOR_EACH_BB (bb)
875 FOR_BB_INSNS (bb, insn)
877 if (INSN_P (insn))
879 /* Check if insn modifies the stack pointer. */
880 note_stores (PATTERN (insn),
881 notice_stack_pointer_modification_1,
882 NULL);
883 if (! current_function_sp_is_unchanging)
884 return;
889 /* Mark a register in SET. Hard registers in large modes get all
890 of their component registers set as well. */
892 static void
893 mark_reg (rtx reg, void *xset)
895 regset set = (regset) xset;
896 int regno = REGNO (reg);
898 gcc_assert (GET_MODE (reg) != BLKmode);
900 SET_REGNO_REG_SET (set, regno);
901 if (regno < FIRST_PSEUDO_REGISTER)
903 int n = hard_regno_nregs[regno][GET_MODE (reg)];
904 while (--n > 0)
905 SET_REGNO_REG_SET (set, regno + n);
909 /* Mark those regs which are needed at the end of the function as live
910 at the end of the last basic block. */
912 static void
913 mark_regs_live_at_end (regset set)
915 unsigned int i;
917 /* If exiting needs the right stack value, consider the stack pointer
918 live at the end of the function. */
919 if ((HAVE_epilogue && epilogue_completed)
920 || ! EXIT_IGNORE_STACK
921 || (! FRAME_POINTER_REQUIRED
922 && ! current_function_calls_alloca
923 && flag_omit_frame_pointer)
924 || current_function_sp_is_unchanging)
926 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
929 /* Mark the frame pointer if needed at the end of the function. If
930 we end up eliminating it, it will be removed from the live list
931 of each basic block by reload. */
933 if (! reload_completed || frame_pointer_needed)
935 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
936 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
937 /* If they are different, also mark the hard frame pointer as live. */
938 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
939 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
940 #endif
943 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
944 /* Many architectures have a GP register even without flag_pic.
945 Assume the pic register is not in use, or will be handled by
946 other means, if it is not fixed. */
947 if ((unsigned) PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
948 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
949 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
950 #endif
952 /* Mark all global registers, and all registers used by the epilogue
953 as being live at the end of the function since they may be
954 referenced by our caller. */
955 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
956 if (global_regs[i] || EPILOGUE_USES (i))
957 SET_REGNO_REG_SET (set, i);
959 if (HAVE_epilogue && epilogue_completed)
961 /* Mark all call-saved registers that we actually used. */
962 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
963 if (regs_ever_live[i] && ! LOCAL_REGNO (i)
964 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
965 SET_REGNO_REG_SET (set, i);
968 #ifdef EH_RETURN_DATA_REGNO
969 /* Mark the registers that will contain data for the handler. */
970 if (reload_completed && current_function_calls_eh_return)
971 for (i = 0; ; ++i)
973 unsigned regno = EH_RETURN_DATA_REGNO(i);
974 if (regno == INVALID_REGNUM)
975 break;
976 SET_REGNO_REG_SET (set, regno);
978 #endif
979 #ifdef EH_RETURN_STACKADJ_RTX
980 if ((! HAVE_epilogue || ! epilogue_completed)
981 && current_function_calls_eh_return)
983 rtx tmp = EH_RETURN_STACKADJ_RTX;
984 if (tmp && REG_P (tmp))
985 mark_reg (tmp, set);
987 #endif
988 #ifdef EH_RETURN_HANDLER_RTX
989 if ((! HAVE_epilogue || ! epilogue_completed)
990 && current_function_calls_eh_return)
992 rtx tmp = EH_RETURN_HANDLER_RTX;
993 if (tmp && REG_P (tmp))
994 mark_reg (tmp, set);
996 #endif
998 /* Mark function return value. */
999 diddle_return_value (mark_reg, set);
1002 /* Propagate global life info around the graph of basic blocks. Begin
1003 considering blocks with their corresponding bit set in BLOCKS_IN.
1004 If BLOCKS_IN is null, consider it the universal set.
1006 BLOCKS_OUT is set for every block that was changed. */
1008 static void
1009 calculate_global_regs_live (sbitmap blocks_in, sbitmap blocks_out, int flags)
1011 basic_block *queue, *qhead, *qtail, *qend, bb;
1012 regset tmp, new_live_at_end, invalidated_by_call;
1014 /* The registers that are modified within this in block. */
1015 regset *local_sets;
1017 /* The registers that are conditionally modified within this block.
1018 In other words, regs that are set only as part of a COND_EXEC. */
1019 regset *cond_local_sets;
1021 int i;
1023 /* Some passes used to forget clear aux field of basic block causing
1024 sick behavior here. */
1025 #ifdef ENABLE_CHECKING
1026 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1027 gcc_assert (!bb->aux);
1028 #endif
1030 tmp = ALLOC_REG_SET (&reg_obstack);
1031 new_live_at_end = ALLOC_REG_SET (&reg_obstack);
1032 invalidated_by_call = ALLOC_REG_SET (&reg_obstack);
1034 /* Inconveniently, this is only readily available in hard reg set form. */
1035 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
1036 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1037 SET_REGNO_REG_SET (invalidated_by_call, i);
1039 /* Allocate space for the sets of local properties. */
1040 local_sets = xcalloc (last_basic_block - (INVALID_BLOCK + 1),
1041 sizeof (regset));
1042 cond_local_sets = xcalloc (last_basic_block - (INVALID_BLOCK + 1),
1043 sizeof (regset));
1045 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1046 because the `head == tail' style test for an empty queue doesn't
1047 work with a full queue. */
1048 queue = xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1)) * sizeof (*queue));
1049 qtail = queue;
1050 qhead = qend = queue + n_basic_blocks - (INVALID_BLOCK + 1);
1052 /* Queue the blocks set in the initial mask. Do this in reverse block
1053 number order so that we are more likely for the first round to do
1054 useful work. We use AUX non-null to flag that the block is queued. */
1055 if (blocks_in)
1057 FOR_EACH_BB (bb)
1058 if (TEST_BIT (blocks_in, bb->index))
1060 *--qhead = bb;
1061 bb->aux = bb;
1064 else
1066 FOR_EACH_BB (bb)
1068 *--qhead = bb;
1069 bb->aux = bb;
1073 /* We clean aux when we remove the initially-enqueued bbs, but we
1074 don't enqueue ENTRY and EXIT initially, so clean them upfront and
1075 unconditionally. */
1076 ENTRY_BLOCK_PTR->aux = EXIT_BLOCK_PTR->aux = NULL;
1078 if (blocks_out)
1079 sbitmap_zero (blocks_out);
1081 /* We work through the queue until there are no more blocks. What
1082 is live at the end of this block is precisely the union of what
1083 is live at the beginning of all its successors. So, we set its
1084 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1085 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1086 this block by walking through the instructions in this block in
1087 reverse order and updating as we go. If that changed
1088 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1089 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1091 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1092 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1093 must either be live at the end of the block, or used within the
1094 block. In the latter case, it will certainly never disappear
1095 from GLOBAL_LIVE_AT_START. In the former case, the register
1096 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1097 for one of the successor blocks. By induction, that cannot
1098 occur. */
1099 while (qhead != qtail)
1101 int rescan, changed;
1102 basic_block bb;
1103 edge e;
1104 edge_iterator ei;
1106 bb = *qhead++;
1107 if (qhead == qend)
1108 qhead = queue;
1109 bb->aux = NULL;
1111 /* Begin by propagating live_at_start from the successor blocks. */
1112 CLEAR_REG_SET (new_live_at_end);
1114 if (EDGE_COUNT (bb->succs) > 0)
1115 FOR_EACH_EDGE (e, ei, bb->succs)
1117 basic_block sb = e->dest;
1119 /* Call-clobbered registers die across exception and
1120 call edges. */
1121 /* ??? Abnormal call edges ignored for the moment, as this gets
1122 confused by sibling call edges, which crashes reg-stack. */
1123 if (e->flags & EDGE_EH)
1124 bitmap_ior_and_compl_into (new_live_at_end,
1125 sb->global_live_at_start,
1126 invalidated_by_call);
1127 else
1128 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
1130 /* If a target saves one register in another (instead of on
1131 the stack) the save register will need to be live for EH. */
1132 if (e->flags & EDGE_EH)
1133 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1134 if (EH_USES (i))
1135 SET_REGNO_REG_SET (new_live_at_end, i);
1137 else
1139 /* This might be a noreturn function that throws. And
1140 even if it isn't, getting the unwind info right helps
1141 debugging. */
1142 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1143 if (EH_USES (i))
1144 SET_REGNO_REG_SET (new_live_at_end, i);
1147 /* The all-important stack pointer must always be live. */
1148 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
1150 /* Before reload, there are a few registers that must be forced
1151 live everywhere -- which might not already be the case for
1152 blocks within infinite loops. */
1153 if (! reload_completed)
1155 /* Any reference to any pseudo before reload is a potential
1156 reference of the frame pointer. */
1157 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
1159 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1160 /* Pseudos with argument area equivalences may require
1161 reloading via the argument pointer. */
1162 if (fixed_regs[ARG_POINTER_REGNUM])
1163 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
1164 #endif
1166 /* Any constant, or pseudo with constant equivalences, may
1167 require reloading from memory using the pic register. */
1168 if ((unsigned) PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
1169 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
1170 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
1173 if (bb == ENTRY_BLOCK_PTR)
1175 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1176 continue;
1179 /* On our first pass through this block, we'll go ahead and continue.
1180 Recognize first pass by checking if local_set is NULL for this
1181 basic block. On subsequent passes, we get to skip out early if
1182 live_at_end wouldn't have changed. */
1184 if (local_sets[bb->index - (INVALID_BLOCK + 1)] == NULL)
1186 local_sets[bb->index - (INVALID_BLOCK + 1)]
1187 = ALLOC_REG_SET (&reg_obstack);
1188 cond_local_sets[bb->index - (INVALID_BLOCK + 1)]
1189 = ALLOC_REG_SET (&reg_obstack);
1190 rescan = 1;
1192 else
1194 /* If any bits were removed from live_at_end, we'll have to
1195 rescan the block. This wouldn't be necessary if we had
1196 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1197 local_live is really dependent on live_at_end. */
1198 rescan = bitmap_intersect_compl_p (bb->global_live_at_end,
1199 new_live_at_end);
1201 if (!rescan)
1203 regset cond_local_set;
1205 /* If any of the registers in the new live_at_end set are
1206 conditionally set in this basic block, we must rescan.
1207 This is because conditional lifetimes at the end of the
1208 block do not just take the live_at_end set into
1209 account, but also the liveness at the start of each
1210 successor block. We can miss changes in those sets if
1211 we only compare the new live_at_end against the
1212 previous one. */
1213 cond_local_set = cond_local_sets[bb->index - (INVALID_BLOCK + 1)];
1214 rescan = bitmap_intersect_p (new_live_at_end, cond_local_set);
1217 if (!rescan)
1219 regset local_set;
1221 /* Find the set of changed bits. Take this opportunity
1222 to notice that this set is empty and early out. */
1223 bitmap_xor (tmp, bb->global_live_at_end, new_live_at_end);
1224 if (bitmap_empty_p (tmp))
1225 continue;
1227 /* If any of the changed bits overlap with local_sets[bb],
1228 we'll have to rescan the block. */
1229 local_set = local_sets[bb->index - (INVALID_BLOCK + 1)];
1230 rescan = bitmap_intersect_p (tmp, local_set);
1234 /* Let our caller know that BB changed enough to require its
1235 death notes updated. */
1236 if (blocks_out)
1237 SET_BIT (blocks_out, bb->index);
1239 if (! rescan)
1241 /* Add to live_at_start the set of all registers in
1242 new_live_at_end that aren't in the old live_at_end. */
1244 changed = bitmap_ior_and_compl_into (bb->global_live_at_start,
1245 new_live_at_end,
1246 bb->global_live_at_end);
1247 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1248 if (! changed)
1249 continue;
1251 else
1253 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1255 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1256 into live_at_start. */
1257 propagate_block (bb, new_live_at_end,
1258 local_sets[bb->index - (INVALID_BLOCK + 1)],
1259 cond_local_sets[bb->index - (INVALID_BLOCK + 1)],
1260 flags);
1262 /* If live_at start didn't change, no need to go farther. */
1263 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
1264 continue;
1266 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
1269 /* Queue all predecessors of BB so that we may re-examine
1270 their live_at_end. */
1271 FOR_EACH_EDGE (e, ei, bb->preds)
1273 basic_block pb = e->src;
1274 if (pb->aux == NULL)
1276 *qtail++ = pb;
1277 if (qtail == qend)
1278 qtail = queue;
1279 pb->aux = pb;
1284 FREE_REG_SET (tmp);
1285 FREE_REG_SET (new_live_at_end);
1286 FREE_REG_SET (invalidated_by_call);
1288 if (blocks_out)
1290 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
1292 basic_block bb = BASIC_BLOCK (i);
1293 FREE_REG_SET (local_sets[bb->index - (INVALID_BLOCK + 1)]);
1294 FREE_REG_SET (cond_local_sets[bb->index - (INVALID_BLOCK + 1)]);
1297 else
1299 FOR_EACH_BB (bb)
1301 FREE_REG_SET (local_sets[bb->index - (INVALID_BLOCK + 1)]);
1302 FREE_REG_SET (cond_local_sets[bb->index - (INVALID_BLOCK + 1)]);
1306 free (queue);
1307 free (cond_local_sets);
1308 free (local_sets);
1312 /* This structure is used to pass parameters to and from the
1313 the function find_regno_partial(). It is used to pass in the
1314 register number we are looking, as well as to return any rtx
1315 we find. */
1317 typedef struct {
1318 unsigned regno_to_find;
1319 rtx retval;
1320 } find_regno_partial_param;
1323 /* Find the rtx for the reg numbers specified in 'data' if it is
1324 part of an expression which only uses part of the register. Return
1325 it in the structure passed in. */
1326 static int
1327 find_regno_partial (rtx *ptr, void *data)
1329 find_regno_partial_param *param = (find_regno_partial_param *)data;
1330 unsigned reg = param->regno_to_find;
1331 param->retval = NULL_RTX;
1333 if (*ptr == NULL_RTX)
1334 return 0;
1336 switch (GET_CODE (*ptr))
1338 case ZERO_EXTRACT:
1339 case SIGN_EXTRACT:
1340 case STRICT_LOW_PART:
1341 if (REG_P (XEXP (*ptr, 0)) && REGNO (XEXP (*ptr, 0)) == reg)
1343 param->retval = XEXP (*ptr, 0);
1344 return 1;
1346 break;
1348 case SUBREG:
1349 if (REG_P (SUBREG_REG (*ptr))
1350 && REGNO (SUBREG_REG (*ptr)) == reg)
1352 param->retval = SUBREG_REG (*ptr);
1353 return 1;
1355 break;
1357 default:
1358 break;
1361 return 0;
1364 /* Process all immediate successors of the entry block looking for pseudo
1365 registers which are live on entry. Find all of those whose first
1366 instance is a partial register reference of some kind, and initialize
1367 them to 0 after the entry block. This will prevent bit sets within
1368 registers whose value is unknown, and may contain some kind of sticky
1369 bits we don't want. */
1372 initialize_uninitialized_subregs (void)
1374 rtx insn;
1375 edge e;
1376 unsigned reg, did_something = 0;
1377 find_regno_partial_param param;
1378 edge_iterator ei;
1380 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
1382 basic_block bb = e->dest;
1383 regset map = bb->global_live_at_start;
1384 reg_set_iterator rsi;
1386 EXECUTE_IF_SET_IN_REG_SET (map, FIRST_PSEUDO_REGISTER, reg, rsi)
1388 int uid = REGNO_FIRST_UID (reg);
1389 rtx i;
1391 /* Find an insn which mentions the register we are looking for.
1392 Its preferable to have an instance of the register's rtl since
1393 there may be various flags set which we need to duplicate.
1394 If we can't find it, its probably an automatic whose initial
1395 value doesn't matter, or hopefully something we don't care about. */
1396 for (i = get_insns (); i && INSN_UID (i) != uid; i = NEXT_INSN (i))
1398 if (i != NULL_RTX)
1400 /* Found the insn, now get the REG rtx, if we can. */
1401 param.regno_to_find = reg;
1402 for_each_rtx (&i, find_regno_partial, &param);
1403 if (param.retval != NULL_RTX)
1405 start_sequence ();
1406 emit_move_insn (param.retval,
1407 CONST0_RTX (GET_MODE (param.retval)));
1408 insn = get_insns ();
1409 end_sequence ();
1410 insert_insn_on_edge (insn, e);
1411 did_something = 1;
1417 if (did_something)
1418 commit_edge_insertions ();
1419 return did_something;
1423 /* Subroutines of life analysis. */
1425 /* Allocate the permanent data structures that represent the results
1426 of life analysis. */
1428 static void
1429 allocate_bb_life_data (void)
1431 basic_block bb;
1433 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1435 bb->global_live_at_start = ALLOC_REG_SET (&reg_obstack);
1436 bb->global_live_at_end = ALLOC_REG_SET (&reg_obstack);
1439 regs_live_at_setjmp = ALLOC_REG_SET (&reg_obstack);
1442 void
1443 allocate_reg_life_data (void)
1445 int i;
1447 max_regno = max_reg_num ();
1448 gcc_assert (!reg_deaths);
1449 reg_deaths = xcalloc (sizeof (*reg_deaths), max_regno);
1451 /* Recalculate the register space, in case it has grown. Old style
1452 vector oriented regsets would set regset_{size,bytes} here also. */
1453 allocate_reg_info (max_regno, FALSE, FALSE);
1455 /* Reset all the data we'll collect in propagate_block and its
1456 subroutines. */
1457 for (i = 0; i < max_regno; i++)
1459 REG_N_SETS (i) = 0;
1460 REG_N_REFS (i) = 0;
1461 REG_N_DEATHS (i) = 0;
1462 REG_N_CALLS_CROSSED (i) = 0;
1463 REG_LIVE_LENGTH (i) = 0;
1464 REG_FREQ (i) = 0;
1465 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
1469 /* Delete dead instructions for propagate_block. */
1471 static void
1472 propagate_block_delete_insn (rtx insn)
1474 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
1476 /* If the insn referred to a label, and that label was attached to
1477 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1478 pretty much mandatory to delete it, because the ADDR_VEC may be
1479 referencing labels that no longer exist.
1481 INSN may reference a deleted label, particularly when a jump
1482 table has been optimized into a direct jump. There's no
1483 real good way to fix up the reference to the deleted label
1484 when the label is deleted, so we just allow it here. */
1486 if (inote && LABEL_P (inote))
1488 rtx label = XEXP (inote, 0);
1489 rtx next;
1491 /* The label may be forced if it has been put in the constant
1492 pool. If that is the only use we must discard the table
1493 jump following it, but not the label itself. */
1494 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
1495 && (next = next_nonnote_insn (label)) != NULL
1496 && JUMP_P (next)
1497 && (GET_CODE (PATTERN (next)) == ADDR_VEC
1498 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
1500 rtx pat = PATTERN (next);
1501 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
1502 int len = XVECLEN (pat, diff_vec_p);
1503 int i;
1505 for (i = 0; i < len; i++)
1506 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
1508 delete_insn_and_edges (next);
1509 ndead++;
1513 delete_insn_and_edges (insn);
1514 ndead++;
1517 /* Delete dead libcalls for propagate_block. Return the insn
1518 before the libcall. */
1520 static rtx
1521 propagate_block_delete_libcall (rtx insn, rtx note)
1523 rtx first = XEXP (note, 0);
1524 rtx before = PREV_INSN (first);
1526 delete_insn_chain_and_edges (first, insn);
1527 ndead++;
1528 return before;
1531 /* Update the life-status of regs for one insn. Return the previous insn. */
1534 propagate_one_insn (struct propagate_block_info *pbi, rtx insn)
1536 rtx prev = PREV_INSN (insn);
1537 int flags = pbi->flags;
1538 int insn_is_dead = 0;
1539 int libcall_is_dead = 0;
1540 rtx note;
1541 unsigned i;
1543 if (! INSN_P (insn))
1544 return prev;
1546 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1547 if (flags & PROP_SCAN_DEAD_CODE)
1549 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
1550 libcall_is_dead = (insn_is_dead && note != 0
1551 && libcall_dead_p (pbi, note, insn));
1554 /* If an instruction consists of just dead store(s) on final pass,
1555 delete it. */
1556 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
1558 /* If we're trying to delete a prologue or epilogue instruction
1559 that isn't flagged as possibly being dead, something is wrong.
1560 But if we are keeping the stack pointer depressed, we might well
1561 be deleting insns that are used to compute the amount to update
1562 it by, so they are fine. */
1563 if (reload_completed
1564 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1565 && (TYPE_RETURNS_STACK_DEPRESSED
1566 (TREE_TYPE (current_function_decl))))
1567 && (((HAVE_epilogue || HAVE_prologue)
1568 && prologue_epilogue_contains (insn))
1569 || (HAVE_sibcall_epilogue
1570 && sibcall_epilogue_contains (insn)))
1571 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
1572 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn);
1574 /* Record sets. Do this even for dead instructions, since they
1575 would have killed the values if they hadn't been deleted. */
1576 mark_set_regs (pbi, PATTERN (insn), insn);
1578 /* CC0 is now known to be dead. Either this insn used it,
1579 in which case it doesn't anymore, or clobbered it,
1580 so the next insn can't use it. */
1581 pbi->cc0_live = 0;
1583 if (libcall_is_dead)
1584 prev = propagate_block_delete_libcall (insn, note);
1585 else
1588 /* If INSN contains a RETVAL note and is dead, but the libcall
1589 as a whole is not dead, then we want to remove INSN, but
1590 not the whole libcall sequence.
1592 However, we need to also remove the dangling REG_LIBCALL
1593 note so that we do not have mis-matched LIBCALL/RETVAL
1594 notes. In theory we could find a new location for the
1595 REG_RETVAL note, but it hardly seems worth the effort.
1597 NOTE at this point will be the RETVAL note if it exists. */
1598 if (note)
1600 rtx libcall_note;
1602 libcall_note
1603 = find_reg_note (XEXP (note, 0), REG_LIBCALL, NULL_RTX);
1604 remove_note (XEXP (note, 0), libcall_note);
1607 /* Similarly if INSN contains a LIBCALL note, remove the
1608 dangling REG_RETVAL note. */
1609 note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
1610 if (note)
1612 rtx retval_note;
1614 retval_note
1615 = find_reg_note (XEXP (note, 0), REG_RETVAL, NULL_RTX);
1616 remove_note (XEXP (note, 0), retval_note);
1619 /* Now delete INSN. */
1620 propagate_block_delete_insn (insn);
1623 return prev;
1626 /* See if this is an increment or decrement that can be merged into
1627 a following memory address. */
1628 #ifdef AUTO_INC_DEC
1630 rtx x = single_set (insn);
1632 /* Does this instruction increment or decrement a register? */
1633 if ((flags & PROP_AUTOINC)
1634 && x != 0
1635 && REG_P (SET_DEST (x))
1636 && (GET_CODE (SET_SRC (x)) == PLUS
1637 || GET_CODE (SET_SRC (x)) == MINUS)
1638 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1639 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1640 /* Ok, look for a following memory ref we can combine with.
1641 If one is found, change the memory ref to a PRE_INC
1642 or PRE_DEC, cancel this insn, and return 1.
1643 Return 0 if nothing has been done. */
1644 && try_pre_increment_1 (pbi, insn))
1645 return prev;
1647 #endif /* AUTO_INC_DEC */
1649 CLEAR_REG_SET (pbi->new_set);
1651 /* If this is not the final pass, and this insn is copying the value of
1652 a library call and it's dead, don't scan the insns that perform the
1653 library call, so that the call's arguments are not marked live. */
1654 if (libcall_is_dead)
1656 /* Record the death of the dest reg. */
1657 mark_set_regs (pbi, PATTERN (insn), insn);
1659 insn = XEXP (note, 0);
1660 return PREV_INSN (insn);
1662 else if (GET_CODE (PATTERN (insn)) == SET
1663 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1664 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1665 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1666 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1668 /* We have an insn to pop a constant amount off the stack.
1669 (Such insns use PLUS regardless of the direction of the stack,
1670 and any insn to adjust the stack by a constant is always a pop
1671 or part of a push.)
1672 These insns, if not dead stores, have no effect on life, though
1673 they do have an effect on the memory stores we are tracking. */
1674 invalidate_mems_from_set (pbi, stack_pointer_rtx);
1675 /* Still, we need to update local_set, lest ifcvt.c:dead_or_predicable
1676 concludes that the stack pointer is not modified. */
1677 mark_set_regs (pbi, PATTERN (insn), insn);
1679 else
1681 rtx note;
1682 /* Any regs live at the time of a call instruction must not go
1683 in a register clobbered by calls. Find all regs now live and
1684 record this for them. */
1686 if (CALL_P (insn) && (flags & PROP_REG_INFO))
1688 reg_set_iterator rsi;
1689 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i, rsi)
1690 REG_N_CALLS_CROSSED (i)++;
1693 /* Record sets. Do this even for dead instructions, since they
1694 would have killed the values if they hadn't been deleted. */
1695 mark_set_regs (pbi, PATTERN (insn), insn);
1697 if (CALL_P (insn))
1699 regset live_at_end;
1700 bool sibcall_p;
1701 rtx note, cond;
1702 int i;
1704 cond = NULL_RTX;
1705 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1706 cond = COND_EXEC_TEST (PATTERN (insn));
1708 /* Non-constant calls clobber memory, constant calls do not
1709 clobber memory, though they may clobber outgoing arguments
1710 on the stack. */
1711 if (! CONST_OR_PURE_CALL_P (insn))
1713 free_EXPR_LIST_list (&pbi->mem_set_list);
1714 pbi->mem_set_list_len = 0;
1716 else
1717 invalidate_mems_from_set (pbi, stack_pointer_rtx);
1719 /* There may be extra registers to be clobbered. */
1720 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1721 note;
1722 note = XEXP (note, 1))
1723 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
1724 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
1725 cond, insn, pbi->flags);
1727 /* Calls change all call-used and global registers; sibcalls do not
1728 clobber anything that must be preserved at end-of-function,
1729 except for return values. */
1731 sibcall_p = SIBLING_CALL_P (insn);
1732 live_at_end = EXIT_BLOCK_PTR->global_live_at_start;
1733 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1734 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i)
1735 && ! (sibcall_p
1736 && REGNO_REG_SET_P (live_at_end, i)
1737 && ! refers_to_regno_p (i, i+1,
1738 current_function_return_rtx,
1739 (rtx *) 0)))
1741 enum rtx_code code = global_regs[i] ? SET : CLOBBER;
1742 /* We do not want REG_UNUSED notes for these registers. */
1743 mark_set_1 (pbi, code, regno_reg_rtx[i], cond, insn,
1744 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
1748 /* If an insn doesn't use CC0, it becomes dead since we assume
1749 that every insn clobbers it. So show it dead here;
1750 mark_used_regs will set it live if it is referenced. */
1751 pbi->cc0_live = 0;
1753 /* Record uses. */
1754 if (! insn_is_dead)
1755 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
1756 if ((flags & PROP_EQUAL_NOTES)
1757 && ((note = find_reg_note (insn, REG_EQUAL, NULL_RTX))
1758 || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX))))
1759 mark_used_regs (pbi, XEXP (note, 0), NULL_RTX, insn);
1761 /* Sometimes we may have inserted something before INSN (such as a move)
1762 when we make an auto-inc. So ensure we will scan those insns. */
1763 #ifdef AUTO_INC_DEC
1764 prev = PREV_INSN (insn);
1765 #endif
1767 if (! insn_is_dead && CALL_P (insn))
1769 int i;
1770 rtx note, cond;
1772 cond = NULL_RTX;
1773 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1774 cond = COND_EXEC_TEST (PATTERN (insn));
1776 /* Calls use their arguments, and may clobber memory which
1777 address involves some register. */
1778 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1779 note;
1780 note = XEXP (note, 1))
1781 /* We find USE or CLOBBER entities in a FUNCTION_USAGE list: both
1782 of which mark_used_regs knows how to handle. */
1783 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0), cond, insn);
1785 /* The stack ptr is used (honorarily) by a CALL insn. */
1786 if ((flags & PROP_REG_INFO)
1787 && !REGNO_REG_SET_P (pbi->reg_live, STACK_POINTER_REGNUM))
1788 reg_deaths[STACK_POINTER_REGNUM] = pbi->insn_num;
1789 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
1791 /* Calls may also reference any of the global registers,
1792 so they are made live. */
1793 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1794 if (global_regs[i])
1795 mark_used_reg (pbi, regno_reg_rtx[i], cond, insn);
1799 pbi->insn_num++;
1801 return prev;
1804 /* Initialize a propagate_block_info struct for public consumption.
1805 Note that the structure itself is opaque to this file, but that
1806 the user can use the regsets provided here. */
1808 struct propagate_block_info *
1809 init_propagate_block_info (basic_block bb, regset live, regset local_set,
1810 regset cond_local_set, int flags)
1812 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
1814 pbi->bb = bb;
1815 pbi->reg_live = live;
1816 pbi->mem_set_list = NULL_RTX;
1817 pbi->mem_set_list_len = 0;
1818 pbi->local_set = local_set;
1819 pbi->cond_local_set = cond_local_set;
1820 pbi->cc0_live = 0;
1821 pbi->flags = flags;
1822 pbi->insn_num = 0;
1824 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
1825 pbi->reg_next_use = xcalloc (max_reg_num (), sizeof (rtx));
1826 else
1827 pbi->reg_next_use = NULL;
1829 pbi->new_set = BITMAP_XMALLOC ();
1831 #ifdef HAVE_conditional_execution
1832 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
1833 free_reg_cond_life_info);
1834 pbi->reg_cond_reg = BITMAP_XMALLOC ();
1836 /* If this block ends in a conditional branch, for each register
1837 live from one side of the branch and not the other, record the
1838 register as conditionally dead. */
1839 if (JUMP_P (BB_END (bb))
1840 && any_condjump_p (BB_END (bb)))
1842 regset diff = ALLOC_REG_SET (&reg_obstack);
1843 basic_block bb_true, bb_false;
1844 unsigned i;
1846 /* Identify the successor blocks. */
1847 bb_true = EDGE_SUCC (bb, 0)->dest;
1848 if (EDGE_COUNT (bb->succs) > 1)
1850 bb_false = EDGE_SUCC (bb, 1)->dest;
1852 if (EDGE_SUCC (bb, 0)->flags & EDGE_FALLTHRU)
1854 basic_block t = bb_false;
1855 bb_false = bb_true;
1856 bb_true = t;
1858 else
1859 gcc_assert (EDGE_SUCC (bb, 1)->flags & EDGE_FALLTHRU);
1861 else
1863 /* This can happen with a conditional jump to the next insn. */
1864 gcc_assert (JUMP_LABEL (BB_END (bb)) == BB_HEAD (bb_true));
1866 /* Simplest way to do nothing. */
1867 bb_false = bb_true;
1870 /* Compute which register lead different lives in the successors. */
1871 bitmap_xor (diff, bb_true->global_live_at_start,
1872 bb_false->global_live_at_start);
1874 if (!bitmap_empty_p (diff))
1876 /* Extract the condition from the branch. */
1877 rtx set_src = SET_SRC (pc_set (BB_END (bb)));
1878 rtx cond_true = XEXP (set_src, 0);
1879 rtx reg = XEXP (cond_true, 0);
1880 enum rtx_code inv_cond;
1882 if (GET_CODE (reg) == SUBREG)
1883 reg = SUBREG_REG (reg);
1885 /* We can only track conditional lifetimes if the condition is
1886 in the form of a reversible comparison of a register against
1887 zero. If the condition is more complex than that, then it is
1888 safe not to record any information. */
1889 inv_cond = reversed_comparison_code (cond_true, BB_END (bb));
1890 if (inv_cond != UNKNOWN
1891 && REG_P (reg)
1892 && XEXP (cond_true, 1) == const0_rtx)
1894 rtx cond_false
1895 = gen_rtx_fmt_ee (inv_cond,
1896 GET_MODE (cond_true), XEXP (cond_true, 0),
1897 XEXP (cond_true, 1));
1898 reg_set_iterator rsi;
1900 if (GET_CODE (XEXP (set_src, 1)) == PC)
1902 rtx t = cond_false;
1903 cond_false = cond_true;
1904 cond_true = t;
1907 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
1909 /* For each such register, mark it conditionally dead. */
1910 EXECUTE_IF_SET_IN_REG_SET (diff, 0, i, rsi)
1912 struct reg_cond_life_info *rcli;
1913 rtx cond;
1915 rcli = xmalloc (sizeof (*rcli));
1917 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
1918 cond = cond_false;
1919 else
1920 cond = cond_true;
1921 rcli->condition = cond;
1922 rcli->stores = const0_rtx;
1923 rcli->orig_condition = cond;
1925 splay_tree_insert (pbi->reg_cond_dead, i,
1926 (splay_tree_value) rcli);
1931 FREE_REG_SET (diff);
1933 #endif
1935 /* If this block has no successors, any stores to the frame that aren't
1936 used later in the block are dead. So make a pass over the block
1937 recording any such that are made and show them dead at the end. We do
1938 a very conservative and simple job here. */
1939 if (optimize
1940 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1941 && (TYPE_RETURNS_STACK_DEPRESSED
1942 (TREE_TYPE (current_function_decl))))
1943 && (flags & PROP_SCAN_DEAD_STORES)
1944 && (EDGE_COUNT (bb->succs) == 0
1945 || (EDGE_COUNT (bb->succs) == 1
1946 && EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
1947 && ! current_function_calls_eh_return)))
1949 rtx insn, set;
1950 for (insn = BB_END (bb); insn != BB_HEAD (bb); insn = PREV_INSN (insn))
1951 if (NONJUMP_INSN_P (insn)
1952 && (set = single_set (insn))
1953 && MEM_P (SET_DEST (set)))
1955 rtx mem = SET_DEST (set);
1956 rtx canon_mem = canon_rtx (mem);
1958 if (XEXP (canon_mem, 0) == frame_pointer_rtx
1959 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
1960 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
1961 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
1962 add_to_mem_set_list (pbi, canon_mem);
1966 return pbi;
1969 /* Release a propagate_block_info struct. */
1971 void
1972 free_propagate_block_info (struct propagate_block_info *pbi)
1974 free_EXPR_LIST_list (&pbi->mem_set_list);
1976 BITMAP_XFREE (pbi->new_set);
1978 #ifdef HAVE_conditional_execution
1979 splay_tree_delete (pbi->reg_cond_dead);
1980 BITMAP_XFREE (pbi->reg_cond_reg);
1981 #endif
1983 if (pbi->flags & PROP_REG_INFO)
1985 int num = pbi->insn_num;
1986 unsigned i;
1987 reg_set_iterator rsi;
1989 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i, rsi)
1991 REG_LIVE_LENGTH (i) += num - reg_deaths[i];
1992 reg_deaths[i] = 0;
1995 if (pbi->reg_next_use)
1996 free (pbi->reg_next_use);
1998 free (pbi);
2001 /* Compute the registers live at the beginning of a basic block BB from
2002 those live at the end.
2004 When called, REG_LIVE contains those live at the end. On return, it
2005 contains those live at the beginning.
2007 LOCAL_SET, if non-null, will be set with all registers killed
2008 unconditionally by this basic block.
2009 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
2010 killed conditionally by this basic block. If there is any unconditional
2011 set of a register, then the corresponding bit will be set in LOCAL_SET
2012 and cleared in COND_LOCAL_SET.
2013 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
2014 case, the resulting set will be equal to the union of the two sets that
2015 would otherwise be computed.
2017 Return nonzero if an INSN is deleted (i.e. by dead code removal). */
2020 propagate_block (basic_block bb, regset live, regset local_set,
2021 regset cond_local_set, int flags)
2023 struct propagate_block_info *pbi;
2024 rtx insn, prev;
2025 int changed;
2027 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
2029 if (flags & PROP_REG_INFO)
2031 unsigned i;
2032 reg_set_iterator rsi;
2034 /* Process the regs live at the end of the block.
2035 Mark them as not local to any one basic block. */
2036 EXECUTE_IF_SET_IN_REG_SET (live, 0, i, rsi)
2037 REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL;
2040 /* Scan the block an insn at a time from end to beginning. */
2042 changed = 0;
2043 for (insn = BB_END (bb); ; insn = prev)
2045 /* If this is a call to `setjmp' et al, warn if any
2046 non-volatile datum is live. */
2047 if ((flags & PROP_REG_INFO)
2048 && CALL_P (insn)
2049 && find_reg_note (insn, REG_SETJMP, NULL))
2050 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
2052 prev = propagate_one_insn (pbi, insn);
2053 if (!prev)
2054 changed |= insn != get_insns ();
2055 else
2056 changed |= NEXT_INSN (prev) != insn;
2058 if (insn == BB_HEAD (bb))
2059 break;
2062 free_propagate_block_info (pbi);
2064 return changed;
2067 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2068 (SET expressions whose destinations are registers dead after the insn).
2069 NEEDED is the regset that says which regs are alive after the insn.
2071 Unless CALL_OK is nonzero, an insn is needed if it contains a CALL.
2073 If X is the entire body of an insn, NOTES contains the reg notes
2074 pertaining to the insn. */
2076 static int
2077 insn_dead_p (struct propagate_block_info *pbi, rtx x, int call_ok,
2078 rtx notes ATTRIBUTE_UNUSED)
2080 enum rtx_code code = GET_CODE (x);
2082 /* Don't eliminate insns that may trap. */
2083 if (flag_non_call_exceptions && may_trap_p (x))
2084 return 0;
2086 #ifdef AUTO_INC_DEC
2087 /* As flow is invoked after combine, we must take existing AUTO_INC
2088 expressions into account. */
2089 for (; notes; notes = XEXP (notes, 1))
2091 if (REG_NOTE_KIND (notes) == REG_INC)
2093 int regno = REGNO (XEXP (notes, 0));
2095 /* Don't delete insns to set global regs. */
2096 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2097 || REGNO_REG_SET_P (pbi->reg_live, regno))
2098 return 0;
2101 #endif
2103 /* If setting something that's a reg or part of one,
2104 see if that register's altered value will be live. */
2106 if (code == SET)
2108 rtx r = SET_DEST (x);
2110 #ifdef HAVE_cc0
2111 if (GET_CODE (r) == CC0)
2112 return ! pbi->cc0_live;
2113 #endif
2115 /* A SET that is a subroutine call cannot be dead. */
2116 if (GET_CODE (SET_SRC (x)) == CALL)
2118 if (! call_ok)
2119 return 0;
2122 /* Don't eliminate loads from volatile memory or volatile asms. */
2123 else if (volatile_refs_p (SET_SRC (x)))
2124 return 0;
2126 if (MEM_P (r))
2128 rtx temp, canon_r;
2130 if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode)
2131 return 0;
2133 canon_r = canon_rtx (r);
2135 /* Walk the set of memory locations we are currently tracking
2136 and see if one is an identical match to this memory location.
2137 If so, this memory write is dead (remember, we're walking
2138 backwards from the end of the block to the start). Since
2139 rtx_equal_p does not check the alias set or flags, we also
2140 must have the potential for them to conflict (anti_dependence). */
2141 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
2142 if (anti_dependence (r, XEXP (temp, 0)))
2144 rtx mem = XEXP (temp, 0);
2146 if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0))
2147 && (GET_MODE_SIZE (GET_MODE (canon_r))
2148 <= GET_MODE_SIZE (GET_MODE (mem))))
2149 return 1;
2151 #ifdef AUTO_INC_DEC
2152 /* Check if memory reference matches an auto increment. Only
2153 post increment/decrement or modify are valid. */
2154 if (GET_MODE (mem) == GET_MODE (r)
2155 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
2156 || GET_CODE (XEXP (mem, 0)) == POST_INC
2157 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
2158 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
2159 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
2160 return 1;
2161 #endif
2164 else
2166 while (GET_CODE (r) == SUBREG
2167 || GET_CODE (r) == STRICT_LOW_PART
2168 || GET_CODE (r) == ZERO_EXTRACT)
2169 r = XEXP (r, 0);
2171 if (REG_P (r))
2173 int regno = REGNO (r);
2175 /* Obvious. */
2176 if (REGNO_REG_SET_P (pbi->reg_live, regno))
2177 return 0;
2179 /* If this is a hard register, verify that subsequent
2180 words are not needed. */
2181 if (regno < FIRST_PSEUDO_REGISTER)
2183 int n = hard_regno_nregs[regno][GET_MODE (r)];
2185 while (--n > 0)
2186 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
2187 return 0;
2190 /* Don't delete insns to set global regs. */
2191 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2192 return 0;
2194 /* Make sure insns to set the stack pointer aren't deleted. */
2195 if (regno == STACK_POINTER_REGNUM)
2196 return 0;
2198 /* ??? These bits might be redundant with the force live bits
2199 in calculate_global_regs_live. We would delete from
2200 sequential sets; whether this actually affects real code
2201 for anything but the stack pointer I don't know. */
2202 /* Make sure insns to set the frame pointer aren't deleted. */
2203 if (regno == FRAME_POINTER_REGNUM
2204 && (! reload_completed || frame_pointer_needed))
2205 return 0;
2206 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2207 if (regno == HARD_FRAME_POINTER_REGNUM
2208 && (! reload_completed || frame_pointer_needed))
2209 return 0;
2210 #endif
2212 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2213 /* Make sure insns to set arg pointer are never deleted
2214 (if the arg pointer isn't fixed, there will be a USE
2215 for it, so we can treat it normally). */
2216 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2217 return 0;
2218 #endif
2220 /* Otherwise, the set is dead. */
2221 return 1;
2226 /* If performing several activities, insn is dead if each activity
2227 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2228 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2229 worth keeping. */
2230 else if (code == PARALLEL)
2232 int i = XVECLEN (x, 0);
2234 for (i--; i >= 0; i--)
2235 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
2236 && GET_CODE (XVECEXP (x, 0, i)) != USE
2237 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
2238 return 0;
2240 return 1;
2243 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2244 is not necessarily true for hard registers until after reload. */
2245 else if (code == CLOBBER)
2247 if (REG_P (XEXP (x, 0))
2248 && (REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
2249 || reload_completed)
2250 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
2251 return 1;
2254 /* ??? A base USE is a historical relic. It ought not be needed anymore.
2255 Instances where it is still used are either (1) temporary and the USE
2256 escaped the pass, (2) cruft and the USE need not be emitted anymore,
2257 or (3) hiding bugs elsewhere that are not properly representing data
2258 flow. */
2260 return 0;
2263 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2264 return 1 if the entire library call is dead.
2265 This is true if INSN copies a register (hard or pseudo)
2266 and if the hard return reg of the call insn is dead.
2267 (The caller should have tested the destination of the SET inside
2268 INSN already for death.)
2270 If this insn doesn't just copy a register, then we don't
2271 have an ordinary libcall. In that case, cse could not have
2272 managed to substitute the source for the dest later on,
2273 so we can assume the libcall is dead.
2275 PBI is the block info giving pseudoregs live before this insn.
2276 NOTE is the REG_RETVAL note of the insn. */
2278 static int
2279 libcall_dead_p (struct propagate_block_info *pbi, rtx note, rtx insn)
2281 rtx x = single_set (insn);
2283 if (x)
2285 rtx r = SET_SRC (x);
2287 if (REG_P (r) || GET_CODE (r) == SUBREG)
2289 rtx call = XEXP (note, 0);
2290 rtx call_pat;
2291 int i;
2293 /* Find the call insn. */
2294 while (call != insn && !CALL_P (call))
2295 call = NEXT_INSN (call);
2297 /* If there is none, do nothing special,
2298 since ordinary death handling can understand these insns. */
2299 if (call == insn)
2300 return 0;
2302 /* See if the hard reg holding the value is dead.
2303 If this is a PARALLEL, find the call within it. */
2304 call_pat = PATTERN (call);
2305 if (GET_CODE (call_pat) == PARALLEL)
2307 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
2308 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
2309 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
2310 break;
2312 /* This may be a library call that is returning a value
2313 via invisible pointer. Do nothing special, since
2314 ordinary death handling can understand these insns. */
2315 if (i < 0)
2316 return 0;
2318 call_pat = XVECEXP (call_pat, 0, i);
2321 if (! insn_dead_p (pbi, call_pat, 1, REG_NOTES (call)))
2322 return 0;
2324 while ((insn = PREV_INSN (insn)) != call)
2326 if (! INSN_P (insn))
2327 continue;
2328 if (! insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn)))
2329 return 0;
2331 return 1;
2334 return 0;
2337 /* 1 if register REGNO was alive at a place where `setjmp' was called
2338 and was set more than once or is an argument.
2339 Such regs may be clobbered by `longjmp'. */
2342 regno_clobbered_at_setjmp (int regno)
2344 if (n_basic_blocks == 0)
2345 return 0;
2347 return ((REG_N_SETS (regno) > 1
2348 || REGNO_REG_SET_P (ENTRY_BLOCK_PTR->global_live_at_end, regno))
2349 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
2352 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2353 maximal list size; look for overlaps in mode and select the largest. */
2354 static void
2355 add_to_mem_set_list (struct propagate_block_info *pbi, rtx mem)
2357 rtx i;
2359 /* We don't know how large a BLKmode store is, so we must not
2360 take them into consideration. */
2361 if (GET_MODE (mem) == BLKmode)
2362 return;
2364 for (i = pbi->mem_set_list; i ; i = XEXP (i, 1))
2366 rtx e = XEXP (i, 0);
2367 if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0)))
2369 if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e)))
2371 #ifdef AUTO_INC_DEC
2372 /* If we must store a copy of the mem, we can just modify
2373 the mode of the stored copy. */
2374 if (pbi->flags & PROP_AUTOINC)
2375 PUT_MODE (e, GET_MODE (mem));
2376 else
2377 #endif
2378 XEXP (i, 0) = mem;
2380 return;
2384 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN)
2386 #ifdef AUTO_INC_DEC
2387 /* Store a copy of mem, otherwise the address may be
2388 scrogged by find_auto_inc. */
2389 if (pbi->flags & PROP_AUTOINC)
2390 mem = shallow_copy_rtx (mem);
2391 #endif
2392 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
2393 pbi->mem_set_list_len++;
2397 /* INSN references memory, possibly using autoincrement addressing modes.
2398 Find any entries on the mem_set_list that need to be invalidated due
2399 to an address change. */
2401 static int
2402 invalidate_mems_from_autoinc (rtx *px, void *data)
2404 rtx x = *px;
2405 struct propagate_block_info *pbi = data;
2407 if (GET_RTX_CLASS (GET_CODE (x)) == RTX_AUTOINC)
2409 invalidate_mems_from_set (pbi, XEXP (x, 0));
2410 return -1;
2413 return 0;
2416 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2418 static void
2419 invalidate_mems_from_set (struct propagate_block_info *pbi, rtx exp)
2421 rtx temp = pbi->mem_set_list;
2422 rtx prev = NULL_RTX;
2423 rtx next;
2425 while (temp)
2427 next = XEXP (temp, 1);
2428 if (reg_overlap_mentioned_p (exp, XEXP (temp, 0)))
2430 /* Splice this entry out of the list. */
2431 if (prev)
2432 XEXP (prev, 1) = next;
2433 else
2434 pbi->mem_set_list = next;
2435 free_EXPR_LIST_node (temp);
2436 pbi->mem_set_list_len--;
2438 else
2439 prev = temp;
2440 temp = next;
2444 /* Process the registers that are set within X. Their bits are set to
2445 1 in the regset DEAD, because they are dead prior to this insn.
2447 If INSN is nonzero, it is the insn being processed.
2449 FLAGS is the set of operations to perform. */
2451 static void
2452 mark_set_regs (struct propagate_block_info *pbi, rtx x, rtx insn)
2454 rtx cond = NULL_RTX;
2455 rtx link;
2456 enum rtx_code code;
2457 int flags = pbi->flags;
2459 if (insn)
2460 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2462 if (REG_NOTE_KIND (link) == REG_INC)
2463 mark_set_1 (pbi, SET, XEXP (link, 0),
2464 (GET_CODE (x) == COND_EXEC
2465 ? COND_EXEC_TEST (x) : NULL_RTX),
2466 insn, flags);
2468 retry:
2469 switch (code = GET_CODE (x))
2471 case SET:
2472 if (GET_CODE (XEXP (x, 1)) == ASM_OPERANDS)
2473 flags |= PROP_ASM_SCAN;
2474 /* Fall through */
2475 case CLOBBER:
2476 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, flags);
2477 return;
2479 case COND_EXEC:
2480 cond = COND_EXEC_TEST (x);
2481 x = COND_EXEC_CODE (x);
2482 goto retry;
2484 case PARALLEL:
2486 int i;
2488 /* We must scan forwards. If we have an asm, we need to set
2489 the PROP_ASM_SCAN flag before scanning the clobbers. */
2490 for (i = 0; i < XVECLEN (x, 0); i++)
2492 rtx sub = XVECEXP (x, 0, i);
2493 switch (code = GET_CODE (sub))
2495 case COND_EXEC:
2496 gcc_assert (!cond);
2498 cond = COND_EXEC_TEST (sub);
2499 sub = COND_EXEC_CODE (sub);
2500 if (GET_CODE (sub) == SET)
2501 goto mark_set;
2502 if (GET_CODE (sub) == CLOBBER)
2503 goto mark_clob;
2504 break;
2506 case SET:
2507 mark_set:
2508 if (GET_CODE (XEXP (sub, 1)) == ASM_OPERANDS)
2509 flags |= PROP_ASM_SCAN;
2510 /* Fall through */
2511 case CLOBBER:
2512 mark_clob:
2513 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, flags);
2514 break;
2516 case ASM_OPERANDS:
2517 flags |= PROP_ASM_SCAN;
2518 break;
2520 default:
2521 break;
2524 break;
2527 default:
2528 break;
2532 /* Process a single set, which appears in INSN. REG (which may not
2533 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2534 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2535 If the set is conditional (because it appear in a COND_EXEC), COND
2536 will be the condition. */
2538 static void
2539 mark_set_1 (struct propagate_block_info *pbi, enum rtx_code code, rtx reg, rtx cond, rtx insn, int flags)
2541 int regno_first = -1, regno_last = -1;
2542 unsigned long not_dead = 0;
2543 int i;
2545 /* Modifying just one hardware register of a multi-reg value or just a
2546 byte field of a register does not mean the value from before this insn
2547 is now dead. Of course, if it was dead after it's unused now. */
2549 switch (GET_CODE (reg))
2551 case PARALLEL:
2552 /* Some targets place small structures in registers for return values of
2553 functions. We have to detect this case specially here to get correct
2554 flow information. */
2555 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
2556 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
2557 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
2558 flags);
2559 return;
2561 case SIGN_EXTRACT:
2562 /* SIGN_EXTRACT cannot be an lvalue. */
2563 gcc_unreachable ();
2565 case ZERO_EXTRACT:
2566 case STRICT_LOW_PART:
2567 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2569 reg = XEXP (reg, 0);
2570 while (GET_CODE (reg) == SUBREG
2571 || GET_CODE (reg) == ZERO_EXTRACT
2572 || GET_CODE (reg) == STRICT_LOW_PART);
2573 if (MEM_P (reg))
2574 break;
2575 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
2576 /* Fall through. */
2578 case REG:
2579 regno_last = regno_first = REGNO (reg);
2580 if (regno_first < FIRST_PSEUDO_REGISTER)
2581 regno_last += hard_regno_nregs[regno_first][GET_MODE (reg)] - 1;
2582 break;
2584 case SUBREG:
2585 if (REG_P (SUBREG_REG (reg)))
2587 enum machine_mode outer_mode = GET_MODE (reg);
2588 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
2590 /* Identify the range of registers affected. This is moderately
2591 tricky for hard registers. See alter_subreg. */
2593 regno_last = regno_first = REGNO (SUBREG_REG (reg));
2594 if (regno_first < FIRST_PSEUDO_REGISTER)
2596 regno_first += subreg_regno_offset (regno_first, inner_mode,
2597 SUBREG_BYTE (reg),
2598 outer_mode);
2599 regno_last = (regno_first
2600 + hard_regno_nregs[regno_first][outer_mode] - 1);
2602 /* Since we've just adjusted the register number ranges, make
2603 sure REG matches. Otherwise some_was_live will be clear
2604 when it shouldn't have been, and we'll create incorrect
2605 REG_UNUSED notes. */
2606 reg = gen_rtx_REG (outer_mode, regno_first);
2608 else
2610 /* If the number of words in the subreg is less than the number
2611 of words in the full register, we have a well-defined partial
2612 set. Otherwise the high bits are undefined.
2614 This is only really applicable to pseudos, since we just took
2615 care of multi-word hard registers. */
2616 if (((GET_MODE_SIZE (outer_mode)
2617 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
2618 < ((GET_MODE_SIZE (inner_mode)
2619 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
2620 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
2621 regno_first);
2623 reg = SUBREG_REG (reg);
2626 else
2627 reg = SUBREG_REG (reg);
2628 break;
2630 default:
2631 break;
2634 /* If this set is a MEM, then it kills any aliased writes.
2635 If this set is a REG, then it kills any MEMs which use the reg. */
2636 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
2638 if (REG_P (reg))
2639 invalidate_mems_from_set (pbi, reg);
2641 /* If the memory reference had embedded side effects (autoincrement
2642 address modes) then we may need to kill some entries on the
2643 memory set list. */
2644 if (insn && MEM_P (reg))
2645 for_each_rtx (&PATTERN (insn), invalidate_mems_from_autoinc, pbi);
2647 if (MEM_P (reg) && ! side_effects_p (reg)
2648 /* ??? With more effort we could track conditional memory life. */
2649 && ! cond)
2650 add_to_mem_set_list (pbi, canon_rtx (reg));
2653 if (REG_P (reg)
2654 && ! (regno_first == FRAME_POINTER_REGNUM
2655 && (! reload_completed || frame_pointer_needed))
2656 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2657 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
2658 && (! reload_completed || frame_pointer_needed))
2659 #endif
2660 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2661 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
2662 #endif
2665 int some_was_live = 0, some_was_dead = 0;
2667 for (i = regno_first; i <= regno_last; ++i)
2669 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
2670 if (pbi->local_set)
2672 /* Order of the set operation matters here since both
2673 sets may be the same. */
2674 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
2675 if (cond != NULL_RTX
2676 && ! REGNO_REG_SET_P (pbi->local_set, i))
2677 SET_REGNO_REG_SET (pbi->cond_local_set, i);
2678 else
2679 SET_REGNO_REG_SET (pbi->local_set, i);
2681 if (code != CLOBBER)
2682 SET_REGNO_REG_SET (pbi->new_set, i);
2684 some_was_live |= needed_regno;
2685 some_was_dead |= ! needed_regno;
2688 #ifdef HAVE_conditional_execution
2689 /* Consider conditional death in deciding that the register needs
2690 a death note. */
2691 if (some_was_live && ! not_dead
2692 /* The stack pointer is never dead. Well, not strictly true,
2693 but it's very difficult to tell from here. Hopefully
2694 combine_stack_adjustments will fix up the most egregious
2695 errors. */
2696 && regno_first != STACK_POINTER_REGNUM)
2698 for (i = regno_first; i <= regno_last; ++i)
2699 if (! mark_regno_cond_dead (pbi, i, cond))
2700 not_dead |= ((unsigned long) 1) << (i - regno_first);
2702 #endif
2704 /* Additional data to record if this is the final pass. */
2705 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
2706 | PROP_DEATH_NOTES | PROP_AUTOINC))
2708 rtx y;
2709 int blocknum = pbi->bb->index;
2711 y = NULL_RTX;
2712 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2714 y = pbi->reg_next_use[regno_first];
2716 /* The next use is no longer next, since a store intervenes. */
2717 for (i = regno_first; i <= regno_last; ++i)
2718 pbi->reg_next_use[i] = 0;
2721 if (flags & PROP_REG_INFO)
2723 for (i = regno_first; i <= regno_last; ++i)
2725 /* Count (weighted) references, stores, etc. This counts a
2726 register twice if it is modified, but that is correct. */
2727 REG_N_SETS (i) += 1;
2728 REG_N_REFS (i) += 1;
2729 REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb);
2731 /* The insns where a reg is live are normally counted
2732 elsewhere, but we want the count to include the insn
2733 where the reg is set, and the normal counting mechanism
2734 would not count it. */
2735 REG_LIVE_LENGTH (i) += 1;
2738 /* If this is a hard reg, record this function uses the reg. */
2739 if (regno_first < FIRST_PSEUDO_REGISTER)
2741 for (i = regno_first; i <= regno_last; i++)
2742 regs_ever_live[i] = 1;
2743 if (flags & PROP_ASM_SCAN)
2744 for (i = regno_first; i <= regno_last; i++)
2745 regs_asm_clobbered[i] = 1;
2747 else
2749 /* Keep track of which basic blocks each reg appears in. */
2750 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
2751 REG_BASIC_BLOCK (regno_first) = blocknum;
2752 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
2753 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
2757 if (! some_was_dead)
2759 if (flags & PROP_LOG_LINKS)
2761 /* Make a logical link from the next following insn
2762 that uses this register, back to this insn.
2763 The following insns have already been processed.
2765 We don't build a LOG_LINK for hard registers containing
2766 in ASM_OPERANDs. If these registers get replaced,
2767 we might wind up changing the semantics of the insn,
2768 even if reload can make what appear to be valid
2769 assignments later.
2771 We don't build a LOG_LINK for global registers to
2772 or from a function call. We don't want to let
2773 combine think that it knows what is going on with
2774 global registers. */
2775 if (y && (BLOCK_NUM (y) == blocknum)
2776 && (regno_first >= FIRST_PSEUDO_REGISTER
2777 || (asm_noperands (PATTERN (y)) < 0
2778 && ! ((CALL_P (insn)
2779 || CALL_P (y))
2780 && global_regs[regno_first]))))
2781 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
2784 else if (not_dead)
2786 else if (! some_was_live)
2788 if (flags & PROP_REG_INFO)
2789 REG_N_DEATHS (regno_first) += 1;
2791 if (flags & PROP_DEATH_NOTES)
2793 /* Note that dead stores have already been deleted
2794 when possible. If we get here, we have found a
2795 dead store that cannot be eliminated (because the
2796 same insn does something useful). Indicate this
2797 by marking the reg being set as dying here. */
2798 REG_NOTES (insn)
2799 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2802 else
2804 if (flags & PROP_DEATH_NOTES)
2806 /* This is a case where we have a multi-word hard register
2807 and some, but not all, of the words of the register are
2808 needed in subsequent insns. Write REG_UNUSED notes
2809 for those parts that were not needed. This case should
2810 be rare. */
2812 for (i = regno_first; i <= regno_last; ++i)
2813 if (! REGNO_REG_SET_P (pbi->reg_live, i))
2814 REG_NOTES (insn)
2815 = alloc_EXPR_LIST (REG_UNUSED,
2816 regno_reg_rtx[i],
2817 REG_NOTES (insn));
2822 /* Mark the register as being dead. */
2823 if (some_was_live
2824 /* The stack pointer is never dead. Well, not strictly true,
2825 but it's very difficult to tell from here. Hopefully
2826 combine_stack_adjustments will fix up the most egregious
2827 errors. */
2828 && regno_first != STACK_POINTER_REGNUM)
2830 for (i = regno_first; i <= regno_last; ++i)
2831 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
2833 if ((pbi->flags & PROP_REG_INFO)
2834 && REGNO_REG_SET_P (pbi->reg_live, i))
2836 REG_LIVE_LENGTH (i) += pbi->insn_num - reg_deaths[i];
2837 reg_deaths[i] = 0;
2839 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
2843 else if (REG_P (reg))
2845 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2846 pbi->reg_next_use[regno_first] = 0;
2848 if ((flags & PROP_REG_INFO) != 0
2849 && (flags & PROP_ASM_SCAN) != 0
2850 && regno_first < FIRST_PSEUDO_REGISTER)
2852 for (i = regno_first; i <= regno_last; i++)
2853 regs_asm_clobbered[i] = 1;
2857 /* If this is the last pass and this is a SCRATCH, show it will be dying
2858 here and count it. */
2859 else if (GET_CODE (reg) == SCRATCH)
2861 if (flags & PROP_DEATH_NOTES)
2862 REG_NOTES (insn)
2863 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2867 #ifdef HAVE_conditional_execution
2868 /* Mark REGNO conditionally dead.
2869 Return true if the register is now unconditionally dead. */
2871 static int
2872 mark_regno_cond_dead (struct propagate_block_info *pbi, int regno, rtx cond)
2874 /* If this is a store to a predicate register, the value of the
2875 predicate is changing, we don't know that the predicate as seen
2876 before is the same as that seen after. Flush all dependent
2877 conditions from reg_cond_dead. This will make all such
2878 conditionally live registers unconditionally live. */
2879 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
2880 flush_reg_cond_reg (pbi, regno);
2882 /* If this is an unconditional store, remove any conditional
2883 life that may have existed. */
2884 if (cond == NULL_RTX)
2885 splay_tree_remove (pbi->reg_cond_dead, regno);
2886 else
2888 splay_tree_node node;
2889 struct reg_cond_life_info *rcli;
2890 rtx ncond;
2892 /* Otherwise this is a conditional set. Record that fact.
2893 It may have been conditionally used, or there may be a
2894 subsequent set with a complementary condition. */
2896 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
2897 if (node == NULL)
2899 /* The register was unconditionally live previously.
2900 Record the current condition as the condition under
2901 which it is dead. */
2902 rcli = xmalloc (sizeof (*rcli));
2903 rcli->condition = cond;
2904 rcli->stores = cond;
2905 rcli->orig_condition = const0_rtx;
2906 splay_tree_insert (pbi->reg_cond_dead, regno,
2907 (splay_tree_value) rcli);
2909 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2911 /* Not unconditionally dead. */
2912 return 0;
2914 else
2916 /* The register was conditionally live previously.
2917 Add the new condition to the old. */
2918 rcli = (struct reg_cond_life_info *) node->value;
2919 ncond = rcli->condition;
2920 ncond = ior_reg_cond (ncond, cond, 1);
2921 if (rcli->stores == const0_rtx)
2922 rcli->stores = cond;
2923 else if (rcli->stores != const1_rtx)
2924 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
2926 /* If the register is now unconditionally dead, remove the entry
2927 in the splay_tree. A register is unconditionally dead if the
2928 dead condition ncond is true. A register is also unconditionally
2929 dead if the sum of all conditional stores is an unconditional
2930 store (stores is true), and the dead condition is identically the
2931 same as the original dead condition initialized at the end of
2932 the block. This is a pointer compare, not an rtx_equal_p
2933 compare. */
2934 if (ncond == const1_rtx
2935 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
2936 splay_tree_remove (pbi->reg_cond_dead, regno);
2937 else
2939 rcli->condition = ncond;
2941 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2943 /* Not unconditionally dead. */
2944 return 0;
2949 return 1;
2952 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2954 static void
2955 free_reg_cond_life_info (splay_tree_value value)
2957 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
2958 free (rcli);
2961 /* Helper function for flush_reg_cond_reg. */
2963 static int
2964 flush_reg_cond_reg_1 (splay_tree_node node, void *data)
2966 struct reg_cond_life_info *rcli;
2967 int *xdata = (int *) data;
2968 unsigned int regno = xdata[0];
2970 /* Don't need to search if last flushed value was farther on in
2971 the in-order traversal. */
2972 if (xdata[1] >= (int) node->key)
2973 return 0;
2975 /* Splice out portions of the expression that refer to regno. */
2976 rcli = (struct reg_cond_life_info *) node->value;
2977 rcli->condition = elim_reg_cond (rcli->condition, regno);
2978 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
2979 rcli->stores = elim_reg_cond (rcli->stores, regno);
2981 /* If the entire condition is now false, signal the node to be removed. */
2982 if (rcli->condition == const0_rtx)
2984 xdata[1] = node->key;
2985 return -1;
2987 else
2988 gcc_assert (rcli->condition != const1_rtx);
2990 return 0;
2993 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2995 static void
2996 flush_reg_cond_reg (struct propagate_block_info *pbi, int regno)
2998 int pair[2];
3000 pair[0] = regno;
3001 pair[1] = -1;
3002 while (splay_tree_foreach (pbi->reg_cond_dead,
3003 flush_reg_cond_reg_1, pair) == -1)
3004 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
3006 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
3009 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
3010 For ior/and, the ADD flag determines whether we want to add the new
3011 condition X to the old one unconditionally. If it is zero, we will
3012 only return a new expression if X allows us to simplify part of
3013 OLD, otherwise we return NULL to the caller.
3014 If ADD is nonzero, we will return a new condition in all cases. The
3015 toplevel caller of one of these functions should always pass 1 for
3016 ADD. */
3018 static rtx
3019 ior_reg_cond (rtx old, rtx x, int add)
3021 rtx op0, op1;
3023 if (COMPARISON_P (old))
3025 if (COMPARISON_P (x)
3026 && REVERSE_CONDEXEC_PREDICATES_P (x, old)
3027 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3028 return const1_rtx;
3029 if (GET_CODE (x) == GET_CODE (old)
3030 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3031 return old;
3032 if (! add)
3033 return NULL;
3034 return gen_rtx_IOR (0, old, x);
3037 switch (GET_CODE (old))
3039 case IOR:
3040 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3041 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3042 if (op0 != NULL || op1 != NULL)
3044 if (op0 == const0_rtx)
3045 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3046 if (op1 == const0_rtx)
3047 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3048 if (op0 == const1_rtx || op1 == const1_rtx)
3049 return const1_rtx;
3050 if (op0 == NULL)
3051 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3052 else if (rtx_equal_p (x, op0))
3053 /* (x | A) | x ~ (x | A). */
3054 return old;
3055 if (op1 == NULL)
3056 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3057 else if (rtx_equal_p (x, op1))
3058 /* (A | x) | x ~ (A | x). */
3059 return old;
3060 return gen_rtx_IOR (0, op0, op1);
3062 if (! add)
3063 return NULL;
3064 return gen_rtx_IOR (0, old, x);
3066 case AND:
3067 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3068 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3069 if (op0 != NULL || op1 != NULL)
3071 if (op0 == const1_rtx)
3072 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3073 if (op1 == const1_rtx)
3074 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3075 if (op0 == const0_rtx || op1 == const0_rtx)
3076 return const0_rtx;
3077 if (op0 == NULL)
3078 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3079 else if (rtx_equal_p (x, op0))
3080 /* (x & A) | x ~ x. */
3081 return op0;
3082 if (op1 == NULL)
3083 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3084 else if (rtx_equal_p (x, op1))
3085 /* (A & x) | x ~ x. */
3086 return op1;
3087 return gen_rtx_AND (0, op0, op1);
3089 if (! add)
3090 return NULL;
3091 return gen_rtx_IOR (0, old, x);
3093 case NOT:
3094 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3095 if (op0 != NULL)
3096 return not_reg_cond (op0);
3097 if (! add)
3098 return NULL;
3099 return gen_rtx_IOR (0, old, x);
3101 default:
3102 gcc_unreachable ();
3106 static rtx
3107 not_reg_cond (rtx x)
3109 if (x == const0_rtx)
3110 return const1_rtx;
3111 else if (x == const1_rtx)
3112 return const0_rtx;
3113 if (GET_CODE (x) == NOT)
3114 return XEXP (x, 0);
3115 if (COMPARISON_P (x)
3116 && REG_P (XEXP (x, 0)))
3118 gcc_assert (XEXP (x, 1) == const0_rtx);
3120 return gen_rtx_fmt_ee (reversed_comparison_code (x, NULL),
3121 VOIDmode, XEXP (x, 0), const0_rtx);
3123 return gen_rtx_NOT (0, x);
3126 static rtx
3127 and_reg_cond (rtx old, rtx x, int add)
3129 rtx op0, op1;
3131 if (COMPARISON_P (old))
3133 if (COMPARISON_P (x)
3134 && GET_CODE (x) == reversed_comparison_code (old, NULL)
3135 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3136 return const0_rtx;
3137 if (GET_CODE (x) == GET_CODE (old)
3138 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3139 return old;
3140 if (! add)
3141 return NULL;
3142 return gen_rtx_AND (0, old, x);
3145 switch (GET_CODE (old))
3147 case IOR:
3148 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3149 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3150 if (op0 != NULL || op1 != NULL)
3152 if (op0 == const0_rtx)
3153 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3154 if (op1 == const0_rtx)
3155 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3156 if (op0 == const1_rtx || op1 == const1_rtx)
3157 return const1_rtx;
3158 if (op0 == NULL)
3159 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3160 else if (rtx_equal_p (x, op0))
3161 /* (x | A) & x ~ x. */
3162 return op0;
3163 if (op1 == NULL)
3164 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3165 else if (rtx_equal_p (x, op1))
3166 /* (A | x) & x ~ x. */
3167 return op1;
3168 return gen_rtx_IOR (0, op0, op1);
3170 if (! add)
3171 return NULL;
3172 return gen_rtx_AND (0, old, x);
3174 case AND:
3175 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3176 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3177 if (op0 != NULL || op1 != NULL)
3179 if (op0 == const1_rtx)
3180 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3181 if (op1 == const1_rtx)
3182 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3183 if (op0 == const0_rtx || op1 == const0_rtx)
3184 return const0_rtx;
3185 if (op0 == NULL)
3186 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3187 else if (rtx_equal_p (x, op0))
3188 /* (x & A) & x ~ (x & A). */
3189 return old;
3190 if (op1 == NULL)
3191 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3192 else if (rtx_equal_p (x, op1))
3193 /* (A & x) & x ~ (A & x). */
3194 return old;
3195 return gen_rtx_AND (0, op0, op1);
3197 if (! add)
3198 return NULL;
3199 return gen_rtx_AND (0, old, x);
3201 case NOT:
3202 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3203 if (op0 != NULL)
3204 return not_reg_cond (op0);
3205 if (! add)
3206 return NULL;
3207 return gen_rtx_AND (0, old, x);
3209 default:
3210 gcc_unreachable ();
3214 /* Given a condition X, remove references to reg REGNO and return the
3215 new condition. The removal will be done so that all conditions
3216 involving REGNO are considered to evaluate to false. This function
3217 is used when the value of REGNO changes. */
3219 static rtx
3220 elim_reg_cond (rtx x, unsigned int regno)
3222 rtx op0, op1;
3224 if (COMPARISON_P (x))
3226 if (REGNO (XEXP (x, 0)) == regno)
3227 return const0_rtx;
3228 return x;
3231 switch (GET_CODE (x))
3233 case AND:
3234 op0 = elim_reg_cond (XEXP (x, 0), regno);
3235 op1 = elim_reg_cond (XEXP (x, 1), regno);
3236 if (op0 == const0_rtx || op1 == const0_rtx)
3237 return const0_rtx;
3238 if (op0 == const1_rtx)
3239 return op1;
3240 if (op1 == const1_rtx)
3241 return op0;
3242 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3243 return x;
3244 return gen_rtx_AND (0, op0, op1);
3246 case IOR:
3247 op0 = elim_reg_cond (XEXP (x, 0), regno);
3248 op1 = elim_reg_cond (XEXP (x, 1), regno);
3249 if (op0 == const1_rtx || op1 == const1_rtx)
3250 return const1_rtx;
3251 if (op0 == const0_rtx)
3252 return op1;
3253 if (op1 == const0_rtx)
3254 return op0;
3255 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3256 return x;
3257 return gen_rtx_IOR (0, op0, op1);
3259 case NOT:
3260 op0 = elim_reg_cond (XEXP (x, 0), regno);
3261 if (op0 == const0_rtx)
3262 return const1_rtx;
3263 if (op0 == const1_rtx)
3264 return const0_rtx;
3265 if (op0 != XEXP (x, 0))
3266 return not_reg_cond (op0);
3267 return x;
3269 default:
3270 gcc_unreachable ();
3273 #endif /* HAVE_conditional_execution */
3275 #ifdef AUTO_INC_DEC
3277 /* Try to substitute the auto-inc expression INC as the address inside
3278 MEM which occurs in INSN. Currently, the address of MEM is an expression
3279 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3280 that has a single set whose source is a PLUS of INCR_REG and something
3281 else. */
3283 static void
3284 attempt_auto_inc (struct propagate_block_info *pbi, rtx inc, rtx insn,
3285 rtx mem, rtx incr, rtx incr_reg)
3287 int regno = REGNO (incr_reg);
3288 rtx set = single_set (incr);
3289 rtx q = SET_DEST (set);
3290 rtx y = SET_SRC (set);
3291 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
3292 int changed;
3294 /* Make sure this reg appears only once in this insn. */
3295 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
3296 return;
3298 if (dead_or_set_p (incr, incr_reg)
3299 /* Mustn't autoinc an eliminable register. */
3300 && (regno >= FIRST_PSEUDO_REGISTER
3301 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
3303 /* This is the simple case. Try to make the auto-inc. If
3304 we can't, we are done. Otherwise, we will do any
3305 needed updates below. */
3306 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
3307 return;
3309 else if (REG_P (q)
3310 /* PREV_INSN used here to check the semi-open interval
3311 [insn,incr). */
3312 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
3313 /* We must also check for sets of q as q may be
3314 a call clobbered hard register and there may
3315 be a call between PREV_INSN (insn) and incr. */
3316 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
3318 /* We have *p followed sometime later by q = p+size.
3319 Both p and q must be live afterward,
3320 and q is not used between INSN and its assignment.
3321 Change it to q = p, ...*q..., q = q+size.
3322 Then fall into the usual case. */
3323 rtx insns, temp;
3325 start_sequence ();
3326 emit_move_insn (q, incr_reg);
3327 insns = get_insns ();
3328 end_sequence ();
3330 /* If we can't make the auto-inc, or can't make the
3331 replacement into Y, exit. There's no point in making
3332 the change below if we can't do the auto-inc and doing
3333 so is not correct in the pre-inc case. */
3335 XEXP (inc, 0) = q;
3336 validate_change (insn, &XEXP (mem, 0), inc, 1);
3337 validate_change (incr, &XEXP (y, opnum), q, 1);
3338 if (! apply_change_group ())
3339 return;
3341 /* We now know we'll be doing this change, so emit the
3342 new insn(s) and do the updates. */
3343 emit_insn_before (insns, insn);
3345 if (BB_HEAD (pbi->bb) == insn)
3346 BB_HEAD (pbi->bb) = insns;
3348 /* INCR will become a NOTE and INSN won't contain a
3349 use of INCR_REG. If a use of INCR_REG was just placed in
3350 the insn before INSN, make that the next use.
3351 Otherwise, invalidate it. */
3352 if (NONJUMP_INSN_P (PREV_INSN (insn))
3353 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
3354 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
3355 pbi->reg_next_use[regno] = PREV_INSN (insn);
3356 else
3357 pbi->reg_next_use[regno] = 0;
3359 incr_reg = q;
3360 regno = REGNO (q);
3362 if ((pbi->flags & PROP_REG_INFO)
3363 && !REGNO_REG_SET_P (pbi->reg_live, regno))
3364 reg_deaths[regno] = pbi->insn_num;
3366 /* REGNO is now used in INCR which is below INSN, but
3367 it previously wasn't live here. If we don't mark
3368 it as live, we'll put a REG_DEAD note for it
3369 on this insn, which is incorrect. */
3370 SET_REGNO_REG_SET (pbi->reg_live, regno);
3372 /* If there are any calls between INSN and INCR, show
3373 that REGNO now crosses them. */
3374 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
3375 if (CALL_P (temp))
3376 REG_N_CALLS_CROSSED (regno)++;
3378 /* Invalidate alias info for Q since we just changed its value. */
3379 clear_reg_alias_info (q);
3381 else
3382 return;
3384 /* If we haven't returned, it means we were able to make the
3385 auto-inc, so update the status. First, record that this insn
3386 has an implicit side effect. */
3388 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
3390 /* Modify the old increment-insn to simply copy
3391 the already-incremented value of our register. */
3392 changed = validate_change (incr, &SET_SRC (set), incr_reg, 0);
3393 gcc_assert (changed);
3395 /* If that makes it a no-op (copying the register into itself) delete
3396 it so it won't appear to be a "use" and a "set" of this
3397 register. */
3398 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
3400 /* If the original source was dead, it's dead now. */
3401 rtx note;
3403 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
3405 remove_note (incr, note);
3406 if (XEXP (note, 0) != incr_reg)
3408 unsigned int regno = REGNO (XEXP (note, 0));
3410 if ((pbi->flags & PROP_REG_INFO)
3411 && REGNO_REG_SET_P (pbi->reg_live, regno))
3413 REG_LIVE_LENGTH (regno) += pbi->insn_num - reg_deaths[regno];
3414 reg_deaths[regno] = 0;
3416 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
3420 SET_INSN_DELETED (incr);
3423 if (regno >= FIRST_PSEUDO_REGISTER)
3425 /* Count an extra reference to the reg. When a reg is
3426 incremented, spilling it is worse, so we want to make
3427 that less likely. */
3428 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3430 /* Count the increment as a setting of the register,
3431 even though it isn't a SET in rtl. */
3432 REG_N_SETS (regno)++;
3436 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3437 reference. */
3439 static void
3440 find_auto_inc (struct propagate_block_info *pbi, rtx x, rtx insn)
3442 rtx addr = XEXP (x, 0);
3443 HOST_WIDE_INT offset = 0;
3444 rtx set, y, incr, inc_val;
3445 int regno;
3446 int size = GET_MODE_SIZE (GET_MODE (x));
3448 if (JUMP_P (insn))
3449 return;
3451 /* Here we detect use of an index register which might be good for
3452 postincrement, postdecrement, preincrement, or predecrement. */
3454 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
3455 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
3457 if (!REG_P (addr))
3458 return;
3460 regno = REGNO (addr);
3462 /* Is the next use an increment that might make auto-increment? */
3463 incr = pbi->reg_next_use[regno];
3464 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
3465 return;
3466 set = single_set (incr);
3467 if (set == 0 || GET_CODE (set) != SET)
3468 return;
3469 y = SET_SRC (set);
3471 if (GET_CODE (y) != PLUS)
3472 return;
3474 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
3475 inc_val = XEXP (y, 1);
3476 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
3477 inc_val = XEXP (y, 0);
3478 else
3479 return;
3481 if (GET_CODE (inc_val) == CONST_INT)
3483 if (HAVE_POST_INCREMENT
3484 && (INTVAL (inc_val) == size && offset == 0))
3485 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
3486 incr, addr);
3487 else if (HAVE_POST_DECREMENT
3488 && (INTVAL (inc_val) == -size && offset == 0))
3489 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
3490 incr, addr);
3491 else if (HAVE_PRE_INCREMENT
3492 && (INTVAL (inc_val) == size && offset == size))
3493 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
3494 incr, addr);
3495 else if (HAVE_PRE_DECREMENT
3496 && (INTVAL (inc_val) == -size && offset == -size))
3497 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
3498 incr, addr);
3499 else if (HAVE_POST_MODIFY_DISP && offset == 0)
3500 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3501 gen_rtx_PLUS (Pmode,
3502 addr,
3503 inc_val)),
3504 insn, x, incr, addr);
3505 else if (HAVE_PRE_MODIFY_DISP && offset == INTVAL (inc_val))
3506 attempt_auto_inc (pbi, gen_rtx_PRE_MODIFY (Pmode, addr,
3507 gen_rtx_PLUS (Pmode,
3508 addr,
3509 inc_val)),
3510 insn, x, incr, addr);
3512 else if (REG_P (inc_val)
3513 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
3514 NEXT_INSN (incr)))
3517 if (HAVE_POST_MODIFY_REG && offset == 0)
3518 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3519 gen_rtx_PLUS (Pmode,
3520 addr,
3521 inc_val)),
3522 insn, x, incr, addr);
3526 #endif /* AUTO_INC_DEC */
3528 static void
3529 mark_used_reg (struct propagate_block_info *pbi, rtx reg,
3530 rtx cond ATTRIBUTE_UNUSED, rtx insn)
3532 unsigned int regno_first, regno_last, i;
3533 int some_was_live, some_was_dead, some_not_set;
3535 regno_last = regno_first = REGNO (reg);
3536 if (regno_first < FIRST_PSEUDO_REGISTER)
3537 regno_last += hard_regno_nregs[regno_first][GET_MODE (reg)] - 1;
3539 /* Find out if any of this register is live after this instruction. */
3540 some_was_live = some_was_dead = 0;
3541 for (i = regno_first; i <= regno_last; ++i)
3543 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
3544 some_was_live |= needed_regno;
3545 some_was_dead |= ! needed_regno;
3548 /* Find out if any of the register was set this insn. */
3549 some_not_set = 0;
3550 for (i = regno_first; i <= regno_last; ++i)
3551 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
3553 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3555 /* Record where each reg is used, so when the reg is set we know
3556 the next insn that uses it. */
3557 pbi->reg_next_use[regno_first] = insn;
3560 if (pbi->flags & PROP_REG_INFO)
3562 if (regno_first < FIRST_PSEUDO_REGISTER)
3564 /* If this is a register we are going to try to eliminate,
3565 don't mark it live here. If we are successful in
3566 eliminating it, it need not be live unless it is used for
3567 pseudos, in which case it will have been set live when it
3568 was allocated to the pseudos. If the register will not
3569 be eliminated, reload will set it live at that point.
3571 Otherwise, record that this function uses this register. */
3572 /* ??? The PPC backend tries to "eliminate" on the pic
3573 register to itself. This should be fixed. In the mean
3574 time, hack around it. */
3576 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
3577 && (regno_first == FRAME_POINTER_REGNUM
3578 || regno_first == ARG_POINTER_REGNUM)))
3579 for (i = regno_first; i <= regno_last; ++i)
3580 regs_ever_live[i] = 1;
3582 else
3584 /* Keep track of which basic block each reg appears in. */
3586 int blocknum = pbi->bb->index;
3587 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
3588 REG_BASIC_BLOCK (regno_first) = blocknum;
3589 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
3590 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
3592 /* Count (weighted) number of uses of each reg. */
3593 REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb);
3594 REG_N_REFS (regno_first)++;
3596 for (i = regno_first; i <= regno_last; ++i)
3597 if (! REGNO_REG_SET_P (pbi->reg_live, i))
3599 gcc_assert (!reg_deaths[i]);
3600 reg_deaths[i] = pbi->insn_num;
3604 /* Record and count the insns in which a reg dies. If it is used in
3605 this insn and was dead below the insn then it dies in this insn.
3606 If it was set in this insn, we do not make a REG_DEAD note;
3607 likewise if we already made such a note. */
3608 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
3609 && some_was_dead
3610 && some_not_set)
3612 /* Check for the case where the register dying partially
3613 overlaps the register set by this insn. */
3614 if (regno_first != regno_last)
3615 for (i = regno_first; i <= regno_last; ++i)
3616 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
3618 /* If none of the words in X is needed, make a REG_DEAD note.
3619 Otherwise, we must make partial REG_DEAD notes. */
3620 if (! some_was_live)
3622 if ((pbi->flags & PROP_DEATH_NOTES)
3623 && ! find_regno_note (insn, REG_DEAD, regno_first))
3624 REG_NOTES (insn)
3625 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
3627 if (pbi->flags & PROP_REG_INFO)
3628 REG_N_DEATHS (regno_first)++;
3630 else
3632 /* Don't make a REG_DEAD note for a part of a register
3633 that is set in the insn. */
3634 for (i = regno_first; i <= regno_last; ++i)
3635 if (! REGNO_REG_SET_P (pbi->reg_live, i)
3636 && ! dead_or_set_regno_p (insn, i))
3637 REG_NOTES (insn)
3638 = alloc_EXPR_LIST (REG_DEAD,
3639 regno_reg_rtx[i],
3640 REG_NOTES (insn));
3644 /* Mark the register as being live. */
3645 for (i = regno_first; i <= regno_last; ++i)
3647 #ifdef HAVE_conditional_execution
3648 int this_was_live = REGNO_REG_SET_P (pbi->reg_live, i);
3649 #endif
3651 SET_REGNO_REG_SET (pbi->reg_live, i);
3653 #ifdef HAVE_conditional_execution
3654 /* If this is a conditional use, record that fact. If it is later
3655 conditionally set, we'll know to kill the register. */
3656 if (cond != NULL_RTX)
3658 splay_tree_node node;
3659 struct reg_cond_life_info *rcli;
3660 rtx ncond;
3662 if (this_was_live)
3664 node = splay_tree_lookup (pbi->reg_cond_dead, i);
3665 if (node == NULL)
3667 /* The register was unconditionally live previously.
3668 No need to do anything. */
3670 else
3672 /* The register was conditionally live previously.
3673 Subtract the new life cond from the old death cond. */
3674 rcli = (struct reg_cond_life_info *) node->value;
3675 ncond = rcli->condition;
3676 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
3678 /* If the register is now unconditionally live,
3679 remove the entry in the splay_tree. */
3680 if (ncond == const0_rtx)
3681 splay_tree_remove (pbi->reg_cond_dead, i);
3682 else
3684 rcli->condition = ncond;
3685 SET_REGNO_REG_SET (pbi->reg_cond_reg,
3686 REGNO (XEXP (cond, 0)));
3690 else
3692 /* The register was not previously live at all. Record
3693 the condition under which it is still dead. */
3694 rcli = xmalloc (sizeof (*rcli));
3695 rcli->condition = not_reg_cond (cond);
3696 rcli->stores = const0_rtx;
3697 rcli->orig_condition = const0_rtx;
3698 splay_tree_insert (pbi->reg_cond_dead, i,
3699 (splay_tree_value) rcli);
3701 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
3704 else if (this_was_live)
3706 /* The register may have been conditionally live previously, but
3707 is now unconditionally live. Remove it from the conditionally
3708 dead list, so that a conditional set won't cause us to think
3709 it dead. */
3710 splay_tree_remove (pbi->reg_cond_dead, i);
3712 #endif
3716 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3717 This is done assuming the registers needed from X are those that
3718 have 1-bits in PBI->REG_LIVE.
3720 INSN is the containing instruction. If INSN is dead, this function
3721 is not called. */
3723 static void
3724 mark_used_regs (struct propagate_block_info *pbi, rtx x, rtx cond, rtx insn)
3726 RTX_CODE code;
3727 int regno;
3728 int flags = pbi->flags;
3730 retry:
3731 if (!x)
3732 return;
3733 code = GET_CODE (x);
3734 switch (code)
3736 case LABEL_REF:
3737 case SYMBOL_REF:
3738 case CONST_INT:
3739 case CONST:
3740 case CONST_DOUBLE:
3741 case CONST_VECTOR:
3742 case PC:
3743 case ADDR_VEC:
3744 case ADDR_DIFF_VEC:
3745 return;
3747 #ifdef HAVE_cc0
3748 case CC0:
3749 pbi->cc0_live = 1;
3750 return;
3751 #endif
3753 case CLOBBER:
3754 /* If we are clobbering a MEM, mark any registers inside the address
3755 as being used. */
3756 if (MEM_P (XEXP (x, 0)))
3757 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
3758 return;
3760 case MEM:
3761 /* Don't bother watching stores to mems if this is not the
3762 final pass. We'll not be deleting dead stores this round. */
3763 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
3765 /* Invalidate the data for the last MEM stored, but only if MEM is
3766 something that can be stored into. */
3767 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3768 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3769 /* Needn't clear the memory set list. */
3771 else
3773 rtx temp = pbi->mem_set_list;
3774 rtx prev = NULL_RTX;
3775 rtx next;
3777 while (temp)
3779 next = XEXP (temp, 1);
3780 if (anti_dependence (XEXP (temp, 0), x))
3782 /* Splice temp out of the list. */
3783 if (prev)
3784 XEXP (prev, 1) = next;
3785 else
3786 pbi->mem_set_list = next;
3787 free_EXPR_LIST_node (temp);
3788 pbi->mem_set_list_len--;
3790 else
3791 prev = temp;
3792 temp = next;
3796 /* If the memory reference had embedded side effects (autoincrement
3797 address modes. Then we may need to kill some entries on the
3798 memory set list. */
3799 if (insn)
3800 for_each_rtx (&PATTERN (insn), invalidate_mems_from_autoinc, pbi);
3803 #ifdef AUTO_INC_DEC
3804 if (flags & PROP_AUTOINC)
3805 find_auto_inc (pbi, x, insn);
3806 #endif
3807 break;
3809 case SUBREG:
3810 #ifdef CANNOT_CHANGE_MODE_CLASS
3811 if (flags & PROP_REG_INFO)
3812 record_subregs_of_mode (x);
3813 #endif
3815 /* While we're here, optimize this case. */
3816 x = SUBREG_REG (x);
3817 if (!REG_P (x))
3818 goto retry;
3819 /* Fall through. */
3821 case REG:
3822 /* See a register other than being set => mark it as needed. */
3823 mark_used_reg (pbi, x, cond, insn);
3824 return;
3826 case SET:
3828 rtx testreg = SET_DEST (x);
3829 int mark_dest = 0;
3831 /* If storing into MEM, don't show it as being used. But do
3832 show the address as being used. */
3833 if (MEM_P (testreg))
3835 #ifdef AUTO_INC_DEC
3836 if (flags & PROP_AUTOINC)
3837 find_auto_inc (pbi, testreg, insn);
3838 #endif
3839 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
3840 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3841 return;
3844 /* Storing in STRICT_LOW_PART is like storing in a reg
3845 in that this SET might be dead, so ignore it in TESTREG.
3846 but in some other ways it is like using the reg.
3848 Storing in a SUBREG or a bit field is like storing the entire
3849 register in that if the register's value is not used
3850 then this SET is not needed. */
3851 while (GET_CODE (testreg) == STRICT_LOW_PART
3852 || GET_CODE (testreg) == ZERO_EXTRACT
3853 || GET_CODE (testreg) == SUBREG)
3855 #ifdef CANNOT_CHANGE_MODE_CLASS
3856 if ((flags & PROP_REG_INFO) && GET_CODE (testreg) == SUBREG)
3857 record_subregs_of_mode (testreg);
3858 #endif
3860 /* Modifying a single register in an alternate mode
3861 does not use any of the old value. But these other
3862 ways of storing in a register do use the old value. */
3863 if (GET_CODE (testreg) == SUBREG
3864 && !((REG_BYTES (SUBREG_REG (testreg))
3865 + UNITS_PER_WORD - 1) / UNITS_PER_WORD
3866 > (REG_BYTES (testreg)
3867 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
3869 else
3870 mark_dest = 1;
3872 testreg = XEXP (testreg, 0);
3875 /* If this is a store into a register or group of registers,
3876 recursively scan the value being stored. */
3878 if ((GET_CODE (testreg) == PARALLEL
3879 && GET_MODE (testreg) == BLKmode)
3880 || (REG_P (testreg)
3881 && (regno = REGNO (testreg),
3882 ! (regno == FRAME_POINTER_REGNUM
3883 && (! reload_completed || frame_pointer_needed)))
3884 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3885 && ! (regno == HARD_FRAME_POINTER_REGNUM
3886 && (! reload_completed || frame_pointer_needed))
3887 #endif
3888 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3889 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
3890 #endif
3893 if (mark_dest)
3894 mark_used_regs (pbi, SET_DEST (x), cond, insn);
3895 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3896 return;
3899 break;
3901 case ASM_OPERANDS:
3902 case UNSPEC_VOLATILE:
3903 case TRAP_IF:
3904 case ASM_INPUT:
3906 /* Traditional and volatile asm instructions must be considered to use
3907 and clobber all hard registers, all pseudo-registers and all of
3908 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3910 Consider for instance a volatile asm that changes the fpu rounding
3911 mode. An insn should not be moved across this even if it only uses
3912 pseudo-regs because it might give an incorrectly rounded result.
3914 ?!? Unfortunately, marking all hard registers as live causes massive
3915 problems for the register allocator and marking all pseudos as live
3916 creates mountains of uninitialized variable warnings.
3918 So for now, just clear the memory set list and mark any regs
3919 we can find in ASM_OPERANDS as used. */
3920 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
3922 free_EXPR_LIST_list (&pbi->mem_set_list);
3923 pbi->mem_set_list_len = 0;
3926 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3927 We can not just fall through here since then we would be confused
3928 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3929 traditional asms unlike their normal usage. */
3930 if (code == ASM_OPERANDS)
3932 int j;
3934 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
3935 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
3937 break;
3940 case COND_EXEC:
3941 gcc_assert (!cond);
3943 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
3945 cond = COND_EXEC_TEST (x);
3946 x = COND_EXEC_CODE (x);
3947 goto retry;
3949 default:
3950 break;
3953 /* Recursively scan the operands of this expression. */
3956 const char * const fmt = GET_RTX_FORMAT (code);
3957 int i;
3959 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3961 if (fmt[i] == 'e')
3963 /* Tail recursive case: save a function call level. */
3964 if (i == 0)
3966 x = XEXP (x, 0);
3967 goto retry;
3969 mark_used_regs (pbi, XEXP (x, i), cond, insn);
3971 else if (fmt[i] == 'E')
3973 int j;
3974 for (j = 0; j < XVECLEN (x, i); j++)
3975 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
3981 #ifdef AUTO_INC_DEC
3983 static int
3984 try_pre_increment_1 (struct propagate_block_info *pbi, rtx insn)
3986 /* Find the next use of this reg. If in same basic block,
3987 make it do pre-increment or pre-decrement if appropriate. */
3988 rtx x = single_set (insn);
3989 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
3990 * INTVAL (XEXP (SET_SRC (x), 1)));
3991 int regno = REGNO (SET_DEST (x));
3992 rtx y = pbi->reg_next_use[regno];
3993 if (y != 0
3994 && SET_DEST (x) != stack_pointer_rtx
3995 && BLOCK_NUM (y) == BLOCK_NUM (insn)
3996 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3997 mode would be better. */
3998 && ! dead_or_set_p (y, SET_DEST (x))
3999 && try_pre_increment (y, SET_DEST (x), amount))
4001 /* We have found a suitable auto-increment and already changed
4002 insn Y to do it. So flush this increment instruction. */
4003 propagate_block_delete_insn (insn);
4005 /* Count a reference to this reg for the increment insn we are
4006 deleting. When a reg is incremented, spilling it is worse,
4007 so we want to make that less likely. */
4008 if (regno >= FIRST_PSEUDO_REGISTER)
4010 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
4011 REG_N_SETS (regno)++;
4014 /* Flush any remembered memories depending on the value of
4015 the incremented register. */
4016 invalidate_mems_from_set (pbi, SET_DEST (x));
4018 return 1;
4020 return 0;
4023 /* Try to change INSN so that it does pre-increment or pre-decrement
4024 addressing on register REG in order to add AMOUNT to REG.
4025 AMOUNT is negative for pre-decrement.
4026 Returns 1 if the change could be made.
4027 This checks all about the validity of the result of modifying INSN. */
4029 static int
4030 try_pre_increment (rtx insn, rtx reg, HOST_WIDE_INT amount)
4032 rtx use;
4034 /* Nonzero if we can try to make a pre-increment or pre-decrement.
4035 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
4036 int pre_ok = 0;
4037 /* Nonzero if we can try to make a post-increment or post-decrement.
4038 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
4039 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
4040 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
4041 int post_ok = 0;
4043 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
4044 int do_post = 0;
4046 /* From the sign of increment, see which possibilities are conceivable
4047 on this target machine. */
4048 if (HAVE_PRE_INCREMENT && amount > 0)
4049 pre_ok = 1;
4050 if (HAVE_POST_INCREMENT && amount > 0)
4051 post_ok = 1;
4053 if (HAVE_PRE_DECREMENT && amount < 0)
4054 pre_ok = 1;
4055 if (HAVE_POST_DECREMENT && amount < 0)
4056 post_ok = 1;
4058 if (! (pre_ok || post_ok))
4059 return 0;
4061 /* It is not safe to add a side effect to a jump insn
4062 because if the incremented register is spilled and must be reloaded
4063 there would be no way to store the incremented value back in memory. */
4065 if (JUMP_P (insn))
4066 return 0;
4068 use = 0;
4069 if (pre_ok)
4070 use = find_use_as_address (PATTERN (insn), reg, 0);
4071 if (post_ok && (use == 0 || use == (rtx) (size_t) 1))
4073 use = find_use_as_address (PATTERN (insn), reg, -amount);
4074 do_post = 1;
4077 if (use == 0 || use == (rtx) (size_t) 1)
4078 return 0;
4080 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
4081 return 0;
4083 /* See if this combination of instruction and addressing mode exists. */
4084 if (! validate_change (insn, &XEXP (use, 0),
4085 gen_rtx_fmt_e (amount > 0
4086 ? (do_post ? POST_INC : PRE_INC)
4087 : (do_post ? POST_DEC : PRE_DEC),
4088 Pmode, reg), 0))
4089 return 0;
4091 /* Record that this insn now has an implicit side effect on X. */
4092 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
4093 return 1;
4096 #endif /* AUTO_INC_DEC */
4098 /* Find the place in the rtx X where REG is used as a memory address.
4099 Return the MEM rtx that so uses it.
4100 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4101 (plus REG (const_int PLUSCONST)).
4103 If such an address does not appear, return 0.
4104 If REG appears more than once, or is used other than in such an address,
4105 return (rtx) 1. */
4108 find_use_as_address (rtx x, rtx reg, HOST_WIDE_INT plusconst)
4110 enum rtx_code code = GET_CODE (x);
4111 const char * const fmt = GET_RTX_FORMAT (code);
4112 int i;
4113 rtx value = 0;
4114 rtx tem;
4116 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
4117 return x;
4119 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
4120 && XEXP (XEXP (x, 0), 0) == reg
4121 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
4122 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
4123 return x;
4125 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
4127 /* If REG occurs inside a MEM used in a bit-field reference,
4128 that is unacceptable. */
4129 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
4130 return (rtx) (size_t) 1;
4133 if (x == reg)
4134 return (rtx) (size_t) 1;
4136 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4138 if (fmt[i] == 'e')
4140 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
4141 if (value == 0)
4142 value = tem;
4143 else if (tem != 0)
4144 return (rtx) (size_t) 1;
4146 else if (fmt[i] == 'E')
4148 int j;
4149 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4151 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
4152 if (value == 0)
4153 value = tem;
4154 else if (tem != 0)
4155 return (rtx) (size_t) 1;
4160 return value;
4163 /* Write information about registers and basic blocks into FILE.
4164 This is part of making a debugging dump. */
4166 void
4167 dump_regset (regset r, FILE *outf)
4169 unsigned i;
4170 reg_set_iterator rsi;
4172 if (r == NULL)
4174 fputs (" (nil)", outf);
4175 return;
4178 EXECUTE_IF_SET_IN_REG_SET (r, 0, i, rsi)
4180 fprintf (outf, " %d", i);
4181 if (i < FIRST_PSEUDO_REGISTER)
4182 fprintf (outf, " [%s]",
4183 reg_names[i]);
4187 /* Print a human-readable representation of R on the standard error
4188 stream. This function is designed to be used from within the
4189 debugger. */
4191 void
4192 debug_regset (regset r)
4194 dump_regset (r, stderr);
4195 putc ('\n', stderr);
4198 /* Recompute register set/reference counts immediately prior to register
4199 allocation.
4201 This avoids problems with set/reference counts changing to/from values
4202 which have special meanings to the register allocators.
4204 Additionally, the reference counts are the primary component used by the
4205 register allocators to prioritize pseudos for allocation to hard regs.
4206 More accurate reference counts generally lead to better register allocation.
4208 F is the first insn to be scanned.
4210 LOOP_STEP denotes how much loop_depth should be incremented per
4211 loop nesting level in order to increase the ref count more for
4212 references in a loop.
4214 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4215 possibly other information which is used by the register allocators. */
4217 void
4218 recompute_reg_usage (rtx f ATTRIBUTE_UNUSED, int loop_step ATTRIBUTE_UNUSED)
4220 allocate_reg_life_data ();
4221 /* distribute_notes in combiner fails to convert some of the REG_UNUSED notes
4222 to REG_DEAD notes. This causes CHECK_DEAD_NOTES in sched1 to abort. To
4223 solve this update the DEATH_NOTES here. */
4224 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO | PROP_DEATH_NOTES);
4227 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4228 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4229 of the number of registers that died. */
4232 count_or_remove_death_notes (sbitmap blocks, int kill)
4234 int count = 0;
4235 int i;
4236 basic_block bb;
4238 /* This used to be a loop over all the blocks with a membership test
4239 inside the loop. That can be amazingly expensive on a large CFG
4240 when only a small number of bits are set in BLOCKs (for example,
4241 the calls from the scheduler typically have very few bits set).
4243 For extra credit, someone should convert BLOCKS to a bitmap rather
4244 than an sbitmap. */
4245 if (blocks)
4247 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4249 count += count_or_remove_death_notes_bb (BASIC_BLOCK (i), kill);
4252 else
4254 FOR_EACH_BB (bb)
4256 count += count_or_remove_death_notes_bb (bb, kill);
4260 return count;
4263 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from basic
4264 block BB. Returns a count of the number of registers that died. */
4266 static int
4267 count_or_remove_death_notes_bb (basic_block bb, int kill)
4269 int count = 0;
4270 rtx insn;
4272 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
4274 if (INSN_P (insn))
4276 rtx *pprev = &REG_NOTES (insn);
4277 rtx link = *pprev;
4279 while (link)
4281 switch (REG_NOTE_KIND (link))
4283 case REG_DEAD:
4284 if (REG_P (XEXP (link, 0)))
4286 rtx reg = XEXP (link, 0);
4287 int n;
4289 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
4290 n = 1;
4291 else
4292 n = hard_regno_nregs[REGNO (reg)][GET_MODE (reg)];
4293 count += n;
4296 /* Fall through. */
4298 case REG_UNUSED:
4299 if (kill)
4301 rtx next = XEXP (link, 1);
4302 free_EXPR_LIST_node (link);
4303 *pprev = link = next;
4304 break;
4306 /* Fall through. */
4308 default:
4309 pprev = &XEXP (link, 1);
4310 link = *pprev;
4311 break;
4316 if (insn == BB_END (bb))
4317 break;
4320 return count;
4323 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4324 if blocks is NULL. */
4326 static void
4327 clear_log_links (sbitmap blocks)
4329 rtx insn;
4330 int i;
4332 if (!blocks)
4334 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4335 if (INSN_P (insn))
4336 free_INSN_LIST_list (&LOG_LINKS (insn));
4338 else
4339 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4341 basic_block bb = BASIC_BLOCK (i);
4343 for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
4344 insn = NEXT_INSN (insn))
4345 if (INSN_P (insn))
4346 free_INSN_LIST_list (&LOG_LINKS (insn));
4350 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4351 correspond to the hard registers, if any, set in that map. This
4352 could be done far more efficiently by having all sorts of special-cases
4353 with moving single words, but probably isn't worth the trouble. */
4355 void
4356 reg_set_to_hard_reg_set (HARD_REG_SET *to, bitmap from)
4358 unsigned i;
4359 bitmap_iterator bi;
4361 EXECUTE_IF_SET_IN_BITMAP (from, 0, i, bi)
4363 if (i >= FIRST_PSEUDO_REGISTER)
4364 return;
4365 SET_HARD_REG_BIT (*to, i);