* config/i386/i386.c (output_387_binary_op,
[official-gcc.git] / gcc / flow.c
blobcc2c19887677586e7fbf920fc70d1e264477f99e
1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
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 /* Size of a regset for the current function,
180 in (1) bytes and (2) elements. */
182 int regset_bytes;
183 int regset_size;
185 /* Regset of regs live when calls to `setjmp'-like functions happen. */
186 /* ??? Does this exist only for the setjmp-clobbered warning message? */
188 regset regs_live_at_setjmp;
190 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
191 that have to go in the same hard reg.
192 The first two regs in the list are a pair, and the next two
193 are another pair, etc. */
194 rtx regs_may_share;
196 /* Set of registers that may be eliminable. These are handled specially
197 in updating regs_ever_live. */
199 static HARD_REG_SET elim_reg_set;
201 /* Holds information for tracking conditional register life information. */
202 struct reg_cond_life_info
204 /* A boolean expression of conditions under which a register is dead. */
205 rtx condition;
206 /* Conditions under which a register is dead at the basic block end. */
207 rtx orig_condition;
209 /* A boolean expression of conditions under which a register has been
210 stored into. */
211 rtx stores;
213 /* ??? Could store mask of bytes that are dead, so that we could finally
214 track lifetimes of multi-word registers accessed via subregs. */
217 /* For use in communicating between propagate_block and its subroutines.
218 Holds all information needed to compute life and def-use information. */
220 struct propagate_block_info
222 /* The basic block we're considering. */
223 basic_block bb;
225 /* Bit N is set if register N is conditionally or unconditionally live. */
226 regset reg_live;
228 /* Bit N is set if register N is set this insn. */
229 regset new_set;
231 /* Element N is the next insn that uses (hard or pseudo) register N
232 within the current basic block; or zero, if there is no such insn. */
233 rtx *reg_next_use;
235 /* Contains a list of all the MEMs we are tracking for dead store
236 elimination. */
237 rtx mem_set_list;
239 /* If non-null, record the set of registers set unconditionally in the
240 basic block. */
241 regset local_set;
243 /* If non-null, record the set of registers set conditionally in the
244 basic block. */
245 regset cond_local_set;
247 #ifdef HAVE_conditional_execution
248 /* Indexed by register number, holds a reg_cond_life_info for each
249 register that is not unconditionally live or dead. */
250 splay_tree reg_cond_dead;
252 /* Bit N is set if register N is in an expression in reg_cond_dead. */
253 regset reg_cond_reg;
254 #endif
256 /* The length of mem_set_list. */
257 int mem_set_list_len;
259 /* Nonzero if the value of CC0 is live. */
260 int cc0_live;
262 /* Flags controlling the set of information propagate_block collects. */
263 int flags;
264 /* Index of instruction being processed. */
265 int insn_num;
268 /* Number of dead insns removed. */
269 static int ndead;
271 /* When PROP_REG_INFO set, array contains pbi->insn_num of instruction
272 where given register died. When the register is marked alive, we use the
273 information to compute amount of instructions life range cross.
274 (remember, we are walking backward). This can be computed as current
275 pbi->insn_num - reg_deaths[regno].
276 At the end of processing each basic block, the remaining live registers
277 are inspected and liferanges are increased same way so liverange of global
278 registers are computed correctly.
280 The array is maintained clear for dead registers, so it can be safely reused
281 for next basic block without expensive memset of the whole array after
282 reseting pbi->insn_num to 0. */
284 static int *reg_deaths;
286 /* Maximum length of pbi->mem_set_list before we start dropping
287 new elements on the floor. */
288 #define MAX_MEM_SET_LIST_LEN 100
290 /* Forward declarations */
291 static int verify_wide_reg_1 (rtx *, void *);
292 static void verify_wide_reg (int, basic_block);
293 static void verify_local_live_at_start (regset, basic_block);
294 static void notice_stack_pointer_modification_1 (rtx, rtx, void *);
295 static void notice_stack_pointer_modification (void);
296 static void mark_reg (rtx, void *);
297 static void mark_regs_live_at_end (regset);
298 static void calculate_global_regs_live (sbitmap, sbitmap, int);
299 static void propagate_block_delete_insn (rtx);
300 static rtx propagate_block_delete_libcall (rtx, rtx);
301 static int insn_dead_p (struct propagate_block_info *, rtx, int, rtx);
302 static int libcall_dead_p (struct propagate_block_info *, rtx, rtx);
303 static void mark_set_regs (struct propagate_block_info *, rtx, rtx);
304 static void mark_set_1 (struct propagate_block_info *, enum rtx_code, rtx,
305 rtx, rtx, int);
306 static int find_regno_partial (rtx *, void *);
308 #ifdef HAVE_conditional_execution
309 static int mark_regno_cond_dead (struct propagate_block_info *, int, rtx);
310 static void free_reg_cond_life_info (splay_tree_value);
311 static int flush_reg_cond_reg_1 (splay_tree_node, void *);
312 static void flush_reg_cond_reg (struct propagate_block_info *, int);
313 static rtx elim_reg_cond (rtx, unsigned int);
314 static rtx ior_reg_cond (rtx, rtx, int);
315 static rtx not_reg_cond (rtx);
316 static rtx and_reg_cond (rtx, rtx, int);
317 #endif
318 #ifdef AUTO_INC_DEC
319 static void attempt_auto_inc (struct propagate_block_info *, rtx, rtx, rtx,
320 rtx, rtx);
321 static void find_auto_inc (struct propagate_block_info *, rtx, rtx);
322 static int try_pre_increment_1 (struct propagate_block_info *, rtx);
323 static int try_pre_increment (rtx, rtx, HOST_WIDE_INT);
324 #endif
325 static void mark_used_reg (struct propagate_block_info *, rtx, rtx, rtx);
326 static void mark_used_regs (struct propagate_block_info *, rtx, rtx, rtx);
327 void debug_flow_info (void);
328 static void add_to_mem_set_list (struct propagate_block_info *, rtx);
329 static int invalidate_mems_from_autoinc (rtx *, void *);
330 static void invalidate_mems_from_set (struct propagate_block_info *, rtx);
331 static void clear_log_links (sbitmap);
332 static int count_or_remove_death_notes_bb (basic_block, int);
333 static void allocate_bb_life_data (void);
335 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
336 note associated with the BLOCK. */
339 first_insn_after_basic_block_note (basic_block block)
341 rtx insn;
343 /* Get the first instruction in the block. */
344 insn = BB_HEAD (block);
346 if (insn == NULL_RTX)
347 return NULL_RTX;
348 if (LABEL_P (insn))
349 insn = NEXT_INSN (insn);
350 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
352 return NEXT_INSN (insn);
355 /* Perform data flow analysis for the whole control flow graph.
356 FLAGS is a set of PROP_* flags to be used in accumulating flow info. */
358 void
359 life_analysis (FILE *file, int flags)
361 #ifdef ELIMINABLE_REGS
362 int i;
363 static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS;
364 #endif
366 /* Record which registers will be eliminated. We use this in
367 mark_used_regs. */
369 CLEAR_HARD_REG_SET (elim_reg_set);
371 #ifdef ELIMINABLE_REGS
372 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
373 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
374 #else
375 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
376 #endif
379 #ifdef CANNOT_CHANGE_MODE_CLASS
380 if (flags & PROP_REG_INFO)
381 init_subregs_of_mode ();
382 #endif
384 if (! optimize)
385 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES);
387 /* The post-reload life analysis have (on a global basis) the same
388 registers live as was computed by reload itself. elimination
389 Otherwise offsets and such may be incorrect.
391 Reload will make some registers as live even though they do not
392 appear in the rtl.
394 We don't want to create new auto-incs after reload, since they
395 are unlikely to be useful and can cause problems with shared
396 stack slots. */
397 if (reload_completed)
398 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
400 /* We want alias analysis information for local dead store elimination. */
401 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
402 init_alias_analysis ();
404 /* Always remove no-op moves. Do this before other processing so
405 that we don't have to keep re-scanning them. */
406 delete_noop_moves ();
408 /* Some targets can emit simpler epilogues if they know that sp was
409 not ever modified during the function. After reload, of course,
410 we've already emitted the epilogue so there's no sense searching. */
411 if (! reload_completed)
412 notice_stack_pointer_modification ();
414 /* Allocate and zero out data structures that will record the
415 data from lifetime analysis. */
416 allocate_reg_life_data ();
417 allocate_bb_life_data ();
419 /* Find the set of registers live on function exit. */
420 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
422 /* "Update" life info from zero. It'd be nice to begin the
423 relaxation with just the exit and noreturn blocks, but that set
424 is not immediately handy. */
426 if (flags & PROP_REG_INFO)
428 memset (regs_ever_live, 0, sizeof (regs_ever_live));
429 memset (regs_asm_clobbered, 0, sizeof (regs_asm_clobbered));
431 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
432 if (reg_deaths)
434 free (reg_deaths);
435 reg_deaths = NULL;
438 /* Clean up. */
439 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
440 end_alias_analysis ();
442 if (file)
443 dump_flow_info (file);
445 /* Removing dead insns should have made jumptables really dead. */
446 delete_dead_jumptables ();
449 /* A subroutine of verify_wide_reg, called through for_each_rtx.
450 Search for REGNO. If found, return 2 if it is not wider than
451 word_mode. */
453 static int
454 verify_wide_reg_1 (rtx *px, void *pregno)
456 rtx x = *px;
457 unsigned int regno = *(int *) pregno;
459 if (REG_P (x) && REGNO (x) == regno)
461 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
462 return 2;
463 return 1;
465 return 0;
468 /* A subroutine of verify_local_live_at_start. Search through insns
469 of BB looking for register REGNO. */
471 static void
472 verify_wide_reg (int regno, basic_block bb)
474 rtx head = BB_HEAD (bb), end = BB_END (bb);
476 while (1)
478 if (INSN_P (head))
480 int r = for_each_rtx (&PATTERN (head), verify_wide_reg_1, &regno);
481 if (r == 1)
482 return;
483 if (r == 2)
484 break;
486 if (head == end)
487 break;
488 head = NEXT_INSN (head);
490 if (dump_file)
492 fprintf (dump_file, "Register %d died unexpectedly.\n", regno);
493 dump_bb (bb, dump_file, 0);
495 fatal_error ("internal consistency failure");
498 /* A subroutine of update_life_info. Verify that there are no untoward
499 changes in live_at_start during a local update. */
501 static void
502 verify_local_live_at_start (regset new_live_at_start, basic_block bb)
504 if (reload_completed)
506 /* After reload, there are no pseudos, nor subregs of multi-word
507 registers. The regsets should exactly match. */
508 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
510 if (dump_file)
512 fprintf (dump_file,
513 "live_at_start mismatch in bb %d, aborting\nNew:\n",
514 bb->index);
515 debug_bitmap_file (dump_file, new_live_at_start);
516 fputs ("Old:\n", dump_file);
517 dump_bb (bb, dump_file, 0);
519 fatal_error ("internal consistency failure");
522 else
524 unsigned i;
525 reg_set_iterator rsi;
527 /* Find the set of changed registers. */
528 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
530 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i, rsi)
532 /* No registers should die. */
533 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
535 if (dump_file)
537 fprintf (dump_file,
538 "Register %d died unexpectedly.\n", i);
539 dump_bb (bb, dump_file, 0);
541 fatal_error ("internal consistency failure");
543 /* Verify that the now-live register is wider than word_mode. */
544 verify_wide_reg (i, bb);
549 /* Updates life information starting with the basic blocks set in BLOCKS.
550 If BLOCKS is null, consider it to be the universal set.
552 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholing,
553 we are only expecting local modifications to basic blocks. If we find
554 extra registers live at the beginning of a block, then we either killed
555 useful data, or we have a broken split that wants data not provided.
556 If we find registers removed from live_at_start, that means we have
557 a broken peephole that is killing a register it shouldn't.
559 ??? This is not true in one situation -- when a pre-reload splitter
560 generates subregs of a multi-word pseudo, current life analysis will
561 lose the kill. So we _can_ have a pseudo go live. How irritating.
563 It is also not true when a peephole decides that it doesn't need one
564 or more of the inputs.
566 Including PROP_REG_INFO does not properly refresh regs_ever_live
567 unless the caller resets it to zero. */
570 update_life_info (sbitmap blocks, enum update_life_extent extent,
571 int prop_flags)
573 regset tmp;
574 unsigned i;
575 int stabilized_prop_flags = prop_flags;
576 basic_block bb;
578 tmp = ALLOC_REG_SET (&reg_obstack);
579 ndead = 0;
581 if ((prop_flags & PROP_REG_INFO) && !reg_deaths)
582 reg_deaths = xcalloc (sizeof (*reg_deaths), max_regno);
584 timevar_push ((extent == UPDATE_LIFE_LOCAL || blocks)
585 ? TV_LIFE_UPDATE : TV_LIFE);
587 /* Changes to the CFG are only allowed when
588 doing a global update for the entire CFG. */
589 gcc_assert (!(prop_flags & PROP_ALLOW_CFG_CHANGES)
590 || (extent != UPDATE_LIFE_LOCAL && !blocks));
592 /* For a global update, we go through the relaxation process again. */
593 if (extent != UPDATE_LIFE_LOCAL)
595 for ( ; ; )
597 int changed = 0;
599 calculate_global_regs_live (blocks, blocks,
600 prop_flags & (PROP_SCAN_DEAD_CODE
601 | PROP_SCAN_DEAD_STORES
602 | PROP_ALLOW_CFG_CHANGES));
604 if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
605 != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
606 break;
608 /* Removing dead code may allow the CFG to be simplified which
609 in turn may allow for further dead code detection / removal. */
610 FOR_EACH_BB_REVERSE (bb)
612 COPY_REG_SET (tmp, bb->global_live_at_end);
613 changed |= propagate_block (bb, tmp, NULL, NULL,
614 prop_flags & (PROP_SCAN_DEAD_CODE
615 | PROP_SCAN_DEAD_STORES
616 | PROP_KILL_DEAD_CODE));
619 /* Don't pass PROP_SCAN_DEAD_CODE or PROP_KILL_DEAD_CODE to
620 subsequent propagate_block calls, since removing or acting as
621 removing dead code can affect global register liveness, which
622 is supposed to be finalized for this call after this loop. */
623 stabilized_prop_flags
624 &= ~(PROP_SCAN_DEAD_CODE | PROP_SCAN_DEAD_STORES
625 | PROP_KILL_DEAD_CODE);
627 if (! changed)
628 break;
630 /* We repeat regardless of what cleanup_cfg says. If there were
631 instructions deleted above, that might have been only a
632 partial improvement (see MAX_MEM_SET_LIST_LEN usage).
633 Further improvement may be possible. */
634 cleanup_cfg (CLEANUP_EXPENSIVE);
636 /* Zap the life information from the last round. If we don't
637 do this, we can wind up with registers that no longer appear
638 in the code being marked live at entry. */
639 FOR_EACH_BB (bb)
641 CLEAR_REG_SET (bb->global_live_at_start);
642 CLEAR_REG_SET (bb->global_live_at_end);
646 /* If asked, remove notes from the blocks we'll update. */
647 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
648 count_or_remove_death_notes (blocks, 1);
651 /* Clear log links in case we are asked to (re)compute them. */
652 if (prop_flags & PROP_LOG_LINKS)
653 clear_log_links (blocks);
655 if (blocks)
657 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
659 bb = BASIC_BLOCK (i);
661 COPY_REG_SET (tmp, bb->global_live_at_end);
662 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags);
664 if (extent == UPDATE_LIFE_LOCAL)
665 verify_local_live_at_start (tmp, bb);
668 else
670 FOR_EACH_BB_REVERSE (bb)
672 COPY_REG_SET (tmp, bb->global_live_at_end);
674 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags);
676 if (extent == UPDATE_LIFE_LOCAL)
677 verify_local_live_at_start (tmp, bb);
681 FREE_REG_SET (tmp);
683 if (prop_flags & PROP_REG_INFO)
685 reg_set_iterator rsi;
687 /* The only pseudos that are live at the beginning of the function
688 are those that were not set anywhere in the function. local-alloc
689 doesn't know how to handle these correctly, so mark them as not
690 local to any one basic block. */
691 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
692 FIRST_PSEUDO_REGISTER, i, rsi)
693 REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL;
695 /* We have a problem with any pseudoreg that lives across the setjmp.
696 ANSI says that if a user variable does not change in value between
697 the setjmp and the longjmp, then the longjmp preserves it. This
698 includes longjmp from a place where the pseudo appears dead.
699 (In principle, the value still exists if it is in scope.)
700 If the pseudo goes in a hard reg, some other value may occupy
701 that hard reg where this pseudo is dead, thus clobbering the pseudo.
702 Conclusion: such a pseudo must not go in a hard reg. */
703 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
704 FIRST_PSEUDO_REGISTER, i, rsi)
706 if (regno_reg_rtx[i] != 0)
708 REG_LIVE_LENGTH (i) = -1;
709 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
713 if (reg_deaths)
715 free (reg_deaths);
716 reg_deaths = NULL;
718 timevar_pop ((extent == UPDATE_LIFE_LOCAL || blocks)
719 ? TV_LIFE_UPDATE : TV_LIFE);
720 if (ndead && dump_file)
721 fprintf (dump_file, "deleted %i dead insns\n", ndead);
722 return ndead;
725 /* Update life information in all blocks where BB_DIRTY is set. */
728 update_life_info_in_dirty_blocks (enum update_life_extent extent, int prop_flags)
730 sbitmap update_life_blocks = sbitmap_alloc (last_basic_block);
731 int n = 0;
732 basic_block bb;
733 int retval = 0;
735 sbitmap_zero (update_life_blocks);
736 FOR_EACH_BB (bb)
738 if (extent == UPDATE_LIFE_LOCAL)
740 if (bb->flags & BB_DIRTY)
742 SET_BIT (update_life_blocks, bb->index);
743 n++;
746 else
748 /* ??? Bootstrap with -march=pentium4 fails to terminate
749 with only a partial life update. */
750 SET_BIT (update_life_blocks, bb->index);
751 if (bb->flags & BB_DIRTY)
752 n++;
756 if (n)
757 retval = update_life_info (update_life_blocks, extent, prop_flags);
759 sbitmap_free (update_life_blocks);
760 return retval;
763 /* Free the variables allocated by find_basic_blocks. */
765 void
766 free_basic_block_vars (void)
768 if (basic_block_info)
770 clear_edges ();
771 basic_block_info = NULL;
773 n_basic_blocks = 0;
774 last_basic_block = 0;
776 ENTRY_BLOCK_PTR->aux = NULL;
777 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
778 EXIT_BLOCK_PTR->aux = NULL;
779 EXIT_BLOCK_PTR->global_live_at_start = NULL;
782 /* Delete any insns that copy a register to itself. */
785 delete_noop_moves (void)
787 rtx insn, next;
788 basic_block bb;
789 int nnoops = 0;
791 FOR_EACH_BB (bb)
793 for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb)); insn = next)
795 next = NEXT_INSN (insn);
796 if (INSN_P (insn) && noop_move_p (insn))
798 rtx note;
800 /* If we're about to remove the first insn of a libcall
801 then move the libcall note to the next real insn and
802 update the retval note. */
803 if ((note = find_reg_note (insn, REG_LIBCALL, NULL_RTX))
804 && XEXP (note, 0) != insn)
806 rtx new_libcall_insn = next_real_insn (insn);
807 rtx retval_note = find_reg_note (XEXP (note, 0),
808 REG_RETVAL, NULL_RTX);
809 REG_NOTES (new_libcall_insn)
810 = gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0),
811 REG_NOTES (new_libcall_insn));
812 XEXP (retval_note, 0) = new_libcall_insn;
815 delete_insn_and_edges (insn);
816 nnoops++;
820 if (nnoops && dump_file)
821 fprintf (dump_file, "deleted %i noop moves", nnoops);
822 return nnoops;
825 /* Delete any jump tables never referenced. We can't delete them at the
826 time of removing tablejump insn as they are referenced by the preceding
827 insns computing the destination, so we delay deleting and garbagecollect
828 them once life information is computed. */
829 void
830 delete_dead_jumptables (void)
832 rtx insn, next;
833 for (insn = get_insns (); insn; insn = next)
835 next = NEXT_INSN (insn);
836 if (LABEL_P (insn)
837 && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
838 && JUMP_P (next)
839 && (GET_CODE (PATTERN (next)) == ADDR_VEC
840 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
842 if (dump_file)
843 fprintf (dump_file, "Dead jumptable %i removed\n", INSN_UID (insn));
844 delete_insn (NEXT_INSN (insn));
845 delete_insn (insn);
846 next = NEXT_INSN (next);
851 /* Determine if the stack pointer is constant over the life of the function.
852 Only useful before prologues have been emitted. */
854 static void
855 notice_stack_pointer_modification_1 (rtx x, rtx pat ATTRIBUTE_UNUSED,
856 void *data ATTRIBUTE_UNUSED)
858 if (x == stack_pointer_rtx
859 /* The stack pointer is only modified indirectly as the result
860 of a push until later in flow. See the comments in rtl.texi
861 regarding Embedded Side-Effects on Addresses. */
862 || (MEM_P (x)
863 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == RTX_AUTOINC
864 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
865 current_function_sp_is_unchanging = 0;
868 static void
869 notice_stack_pointer_modification (void)
871 basic_block bb;
872 rtx insn;
874 /* Assume that the stack pointer is unchanging if alloca hasn't
875 been used. */
876 current_function_sp_is_unchanging = !current_function_calls_alloca;
877 if (! current_function_sp_is_unchanging)
878 return;
880 FOR_EACH_BB (bb)
881 FOR_BB_INSNS (bb, insn)
883 if (INSN_P (insn))
885 /* Check if insn modifies the stack pointer. */
886 note_stores (PATTERN (insn),
887 notice_stack_pointer_modification_1,
888 NULL);
889 if (! current_function_sp_is_unchanging)
890 return;
895 /* Mark a register in SET. Hard registers in large modes get all
896 of their component registers set as well. */
898 static void
899 mark_reg (rtx reg, void *xset)
901 regset set = (regset) xset;
902 int regno = REGNO (reg);
904 gcc_assert (GET_MODE (reg) != BLKmode);
906 SET_REGNO_REG_SET (set, regno);
907 if (regno < FIRST_PSEUDO_REGISTER)
909 int n = hard_regno_nregs[regno][GET_MODE (reg)];
910 while (--n > 0)
911 SET_REGNO_REG_SET (set, regno + n);
915 /* Mark those regs which are needed at the end of the function as live
916 at the end of the last basic block. */
918 static void
919 mark_regs_live_at_end (regset set)
921 unsigned int i;
923 /* If exiting needs the right stack value, consider the stack pointer
924 live at the end of the function. */
925 if ((HAVE_epilogue && epilogue_completed)
926 || ! EXIT_IGNORE_STACK
927 || (! FRAME_POINTER_REQUIRED
928 && ! current_function_calls_alloca
929 && flag_omit_frame_pointer)
930 || current_function_sp_is_unchanging)
932 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
935 /* Mark the frame pointer if needed at the end of the function. If
936 we end up eliminating it, it will be removed from the live list
937 of each basic block by reload. */
939 if (! reload_completed || frame_pointer_needed)
941 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
942 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
943 /* If they are different, also mark the hard frame pointer as live. */
944 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
945 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
946 #endif
949 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
950 /* Many architectures have a GP register even without flag_pic.
951 Assume the pic register is not in use, or will be handled by
952 other means, if it is not fixed. */
953 if ((unsigned) PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
954 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
955 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
956 #endif
958 /* Mark all global registers, and all registers used by the epilogue
959 as being live at the end of the function since they may be
960 referenced by our caller. */
961 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
962 if (global_regs[i] || EPILOGUE_USES (i))
963 SET_REGNO_REG_SET (set, i);
965 if (HAVE_epilogue && epilogue_completed)
967 /* Mark all call-saved registers that we actually used. */
968 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
969 if (regs_ever_live[i] && ! LOCAL_REGNO (i)
970 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
971 SET_REGNO_REG_SET (set, i);
974 #ifdef EH_RETURN_DATA_REGNO
975 /* Mark the registers that will contain data for the handler. */
976 if (reload_completed && current_function_calls_eh_return)
977 for (i = 0; ; ++i)
979 unsigned regno = EH_RETURN_DATA_REGNO(i);
980 if (regno == INVALID_REGNUM)
981 break;
982 SET_REGNO_REG_SET (set, regno);
984 #endif
985 #ifdef EH_RETURN_STACKADJ_RTX
986 if ((! HAVE_epilogue || ! epilogue_completed)
987 && current_function_calls_eh_return)
989 rtx tmp = EH_RETURN_STACKADJ_RTX;
990 if (tmp && REG_P (tmp))
991 mark_reg (tmp, set);
993 #endif
994 #ifdef EH_RETURN_HANDLER_RTX
995 if ((! HAVE_epilogue || ! epilogue_completed)
996 && current_function_calls_eh_return)
998 rtx tmp = EH_RETURN_HANDLER_RTX;
999 if (tmp && REG_P (tmp))
1000 mark_reg (tmp, set);
1002 #endif
1004 /* Mark function return value. */
1005 diddle_return_value (mark_reg, set);
1008 /* Propagate global life info around the graph of basic blocks. Begin
1009 considering blocks with their corresponding bit set in BLOCKS_IN.
1010 If BLOCKS_IN is null, consider it the universal set.
1012 BLOCKS_OUT is set for every block that was changed. */
1014 static void
1015 calculate_global_regs_live (sbitmap blocks_in, sbitmap blocks_out, int flags)
1017 basic_block *queue, *qhead, *qtail, *qend, bb;
1018 regset tmp, new_live_at_end, invalidated_by_call;
1020 /* The registers that are modified within this in block. */
1021 regset *local_sets;
1023 /* The registers that are conditionally modified within this block.
1024 In other words, regs that are set only as part of a COND_EXEC. */
1025 regset *cond_local_sets;
1027 int i;
1029 /* Some passes used to forget clear aux field of basic block causing
1030 sick behavior here. */
1031 #ifdef ENABLE_CHECKING
1032 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1033 gcc_assert (!bb->aux);
1034 #endif
1036 tmp = ALLOC_REG_SET (&reg_obstack);
1037 new_live_at_end = ALLOC_REG_SET (&reg_obstack);
1038 invalidated_by_call = ALLOC_REG_SET (&reg_obstack);
1040 /* Inconveniently, this is only readily available in hard reg set form. */
1041 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
1042 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1043 SET_REGNO_REG_SET (invalidated_by_call, i);
1045 /* Allocate space for the sets of local properties. */
1046 local_sets = xcalloc (last_basic_block - (INVALID_BLOCK + 1),
1047 sizeof (regset));
1048 cond_local_sets = xcalloc (last_basic_block - (INVALID_BLOCK + 1),
1049 sizeof (regset));
1051 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1052 because the `head == tail' style test for an empty queue doesn't
1053 work with a full queue. */
1054 queue = xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1)) * sizeof (*queue));
1055 qtail = queue;
1056 qhead = qend = queue + n_basic_blocks - (INVALID_BLOCK + 1);
1058 /* Queue the blocks set in the initial mask. Do this in reverse block
1059 number order so that we are more likely for the first round to do
1060 useful work. We use AUX non-null to flag that the block is queued. */
1061 if (blocks_in)
1063 FOR_EACH_BB (bb)
1064 if (TEST_BIT (blocks_in, bb->index))
1066 *--qhead = bb;
1067 bb->aux = bb;
1070 else
1072 FOR_EACH_BB (bb)
1074 *--qhead = bb;
1075 bb->aux = bb;
1079 /* We clean aux when we remove the initially-enqueued bbs, but we
1080 don't enqueue ENTRY and EXIT initially, so clean them upfront and
1081 unconditionally. */
1082 ENTRY_BLOCK_PTR->aux = EXIT_BLOCK_PTR->aux = NULL;
1084 if (blocks_out)
1085 sbitmap_zero (blocks_out);
1087 /* We work through the queue until there are no more blocks. What
1088 is live at the end of this block is precisely the union of what
1089 is live at the beginning of all its successors. So, we set its
1090 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1091 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1092 this block by walking through the instructions in this block in
1093 reverse order and updating as we go. If that changed
1094 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1095 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1097 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1098 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1099 must either be live at the end of the block, or used within the
1100 block. In the latter case, it will certainly never disappear
1101 from GLOBAL_LIVE_AT_START. In the former case, the register
1102 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1103 for one of the successor blocks. By induction, that cannot
1104 occur. */
1105 while (qhead != qtail)
1107 int rescan, changed;
1108 basic_block bb;
1109 edge e;
1110 edge_iterator ei;
1112 bb = *qhead++;
1113 if (qhead == qend)
1114 qhead = queue;
1115 bb->aux = NULL;
1117 /* Begin by propagating live_at_start from the successor blocks. */
1118 CLEAR_REG_SET (new_live_at_end);
1120 if (EDGE_COUNT (bb->succs) > 0)
1121 FOR_EACH_EDGE (e, ei, bb->succs)
1123 basic_block sb = e->dest;
1125 /* Call-clobbered registers die across exception and
1126 call edges. */
1127 /* ??? Abnormal call edges ignored for the moment, as this gets
1128 confused by sibling call edges, which crashes reg-stack. */
1129 if (e->flags & EDGE_EH)
1130 bitmap_ior_and_compl_into (new_live_at_end,
1131 sb->global_live_at_start,
1132 invalidated_by_call);
1133 else
1134 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
1136 /* If a target saves one register in another (instead of on
1137 the stack) the save register will need to be live for EH. */
1138 if (e->flags & EDGE_EH)
1139 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1140 if (EH_USES (i))
1141 SET_REGNO_REG_SET (new_live_at_end, i);
1143 else
1145 /* This might be a noreturn function that throws. And
1146 even if it isn't, getting the unwind info right helps
1147 debugging. */
1148 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1149 if (EH_USES (i))
1150 SET_REGNO_REG_SET (new_live_at_end, i);
1153 /* The all-important stack pointer must always be live. */
1154 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
1156 /* Before reload, there are a few registers that must be forced
1157 live everywhere -- which might not already be the case for
1158 blocks within infinite loops. */
1159 if (! reload_completed)
1161 /* Any reference to any pseudo before reload is a potential
1162 reference of the frame pointer. */
1163 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
1165 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1166 /* Pseudos with argument area equivalences may require
1167 reloading via the argument pointer. */
1168 if (fixed_regs[ARG_POINTER_REGNUM])
1169 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
1170 #endif
1172 /* Any constant, or pseudo with constant equivalences, may
1173 require reloading from memory using the pic register. */
1174 if ((unsigned) PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
1175 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
1176 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
1179 if (bb == ENTRY_BLOCK_PTR)
1181 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1182 continue;
1185 /* On our first pass through this block, we'll go ahead and continue.
1186 Recognize first pass by checking if local_set is NULL for this
1187 basic block. On subsequent passes, we get to skip out early if
1188 live_at_end wouldn't have changed. */
1190 if (local_sets[bb->index - (INVALID_BLOCK + 1)] == NULL)
1192 local_sets[bb->index - (INVALID_BLOCK + 1)]
1193 = ALLOC_REG_SET (&reg_obstack);
1194 cond_local_sets[bb->index - (INVALID_BLOCK + 1)]
1195 = ALLOC_REG_SET (&reg_obstack);
1196 rescan = 1;
1198 else
1200 /* If any bits were removed from live_at_end, we'll have to
1201 rescan the block. This wouldn't be necessary if we had
1202 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1203 local_live is really dependent on live_at_end. */
1204 rescan = bitmap_intersect_compl_p (bb->global_live_at_end,
1205 new_live_at_end);
1207 if (!rescan)
1209 regset cond_local_set;
1211 /* If any of the registers in the new live_at_end set are
1212 conditionally set in this basic block, we must rescan.
1213 This is because conditional lifetimes at the end of the
1214 block do not just take the live_at_end set into
1215 account, but also the liveness at the start of each
1216 successor block. We can miss changes in those sets if
1217 we only compare the new live_at_end against the
1218 previous one. */
1219 cond_local_set = cond_local_sets[bb->index - (INVALID_BLOCK + 1)];
1220 rescan = bitmap_intersect_p (new_live_at_end, cond_local_set);
1223 if (!rescan)
1225 regset local_set;
1227 /* Find the set of changed bits. Take this opportunity
1228 to notice that this set is empty and early out. */
1229 bitmap_xor (tmp, bb->global_live_at_end, new_live_at_end);
1230 if (bitmap_empty_p (tmp))
1231 continue;
1233 /* If any of the changed bits overlap with local_sets[bb],
1234 we'll have to rescan the block. */
1235 local_set = local_sets[bb->index - (INVALID_BLOCK + 1)];
1236 rescan = bitmap_intersect_p (tmp, local_set);
1240 /* Let our caller know that BB changed enough to require its
1241 death notes updated. */
1242 if (blocks_out)
1243 SET_BIT (blocks_out, bb->index);
1245 if (! rescan)
1247 /* Add to live_at_start the set of all registers in
1248 new_live_at_end that aren't in the old live_at_end. */
1250 changed = bitmap_ior_and_compl_into (bb->global_live_at_start,
1251 new_live_at_end,
1252 bb->global_live_at_end);
1253 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1254 if (! changed)
1255 continue;
1257 else
1259 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1261 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1262 into live_at_start. */
1263 propagate_block (bb, new_live_at_end,
1264 local_sets[bb->index - (INVALID_BLOCK + 1)],
1265 cond_local_sets[bb->index - (INVALID_BLOCK + 1)],
1266 flags);
1268 /* If live_at start didn't change, no need to go farther. */
1269 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
1270 continue;
1272 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
1275 /* Queue all predecessors of BB so that we may re-examine
1276 their live_at_end. */
1277 FOR_EACH_EDGE (e, ei, bb->preds)
1279 basic_block pb = e->src;
1280 if (pb->aux == NULL)
1282 *qtail++ = pb;
1283 if (qtail == qend)
1284 qtail = queue;
1285 pb->aux = pb;
1290 FREE_REG_SET (tmp);
1291 FREE_REG_SET (new_live_at_end);
1292 FREE_REG_SET (invalidated_by_call);
1294 if (blocks_out)
1296 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
1298 basic_block bb = BASIC_BLOCK (i);
1299 FREE_REG_SET (local_sets[bb->index - (INVALID_BLOCK + 1)]);
1300 FREE_REG_SET (cond_local_sets[bb->index - (INVALID_BLOCK + 1)]);
1303 else
1305 FOR_EACH_BB (bb)
1307 FREE_REG_SET (local_sets[bb->index - (INVALID_BLOCK + 1)]);
1308 FREE_REG_SET (cond_local_sets[bb->index - (INVALID_BLOCK + 1)]);
1312 free (queue);
1313 free (cond_local_sets);
1314 free (local_sets);
1318 /* This structure is used to pass parameters to and from the
1319 the function find_regno_partial(). It is used to pass in the
1320 register number we are looking, as well as to return any rtx
1321 we find. */
1323 typedef struct {
1324 unsigned regno_to_find;
1325 rtx retval;
1326 } find_regno_partial_param;
1329 /* Find the rtx for the reg numbers specified in 'data' if it is
1330 part of an expression which only uses part of the register. Return
1331 it in the structure passed in. */
1332 static int
1333 find_regno_partial (rtx *ptr, void *data)
1335 find_regno_partial_param *param = (find_regno_partial_param *)data;
1336 unsigned reg = param->regno_to_find;
1337 param->retval = NULL_RTX;
1339 if (*ptr == NULL_RTX)
1340 return 0;
1342 switch (GET_CODE (*ptr))
1344 case ZERO_EXTRACT:
1345 case SIGN_EXTRACT:
1346 case STRICT_LOW_PART:
1347 if (REG_P (XEXP (*ptr, 0)) && REGNO (XEXP (*ptr, 0)) == reg)
1349 param->retval = XEXP (*ptr, 0);
1350 return 1;
1352 break;
1354 case SUBREG:
1355 if (REG_P (SUBREG_REG (*ptr))
1356 && REGNO (SUBREG_REG (*ptr)) == reg)
1358 param->retval = SUBREG_REG (*ptr);
1359 return 1;
1361 break;
1363 default:
1364 break;
1367 return 0;
1370 /* Process all immediate successors of the entry block looking for pseudo
1371 registers which are live on entry. Find all of those whose first
1372 instance is a partial register reference of some kind, and initialize
1373 them to 0 after the entry block. This will prevent bit sets within
1374 registers whose value is unknown, and may contain some kind of sticky
1375 bits we don't want. */
1378 initialize_uninitialized_subregs (void)
1380 rtx insn;
1381 edge e;
1382 unsigned reg, did_something = 0;
1383 find_regno_partial_param param;
1384 edge_iterator ei;
1386 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
1388 basic_block bb = e->dest;
1389 regset map = bb->global_live_at_start;
1390 reg_set_iterator rsi;
1392 EXECUTE_IF_SET_IN_REG_SET (map, FIRST_PSEUDO_REGISTER, reg, rsi)
1394 int uid = REGNO_FIRST_UID (reg);
1395 rtx i;
1397 /* Find an insn which mentions the register we are looking for.
1398 Its preferable to have an instance of the register's rtl since
1399 there may be various flags set which we need to duplicate.
1400 If we can't find it, its probably an automatic whose initial
1401 value doesn't matter, or hopefully something we don't care about. */
1402 for (i = get_insns (); i && INSN_UID (i) != uid; i = NEXT_INSN (i))
1404 if (i != NULL_RTX)
1406 /* Found the insn, now get the REG rtx, if we can. */
1407 param.regno_to_find = reg;
1408 for_each_rtx (&i, find_regno_partial, &param);
1409 if (param.retval != NULL_RTX)
1411 start_sequence ();
1412 emit_move_insn (param.retval,
1413 CONST0_RTX (GET_MODE (param.retval)));
1414 insn = get_insns ();
1415 end_sequence ();
1416 insert_insn_on_edge (insn, e);
1417 did_something = 1;
1423 if (did_something)
1424 commit_edge_insertions ();
1425 return did_something;
1429 /* Subroutines of life analysis. */
1431 /* Allocate the permanent data structures that represent the results
1432 of life analysis. */
1434 static void
1435 allocate_bb_life_data (void)
1437 basic_block bb;
1439 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1441 bb->global_live_at_start = ALLOC_REG_SET (&reg_obstack);
1442 bb->global_live_at_end = ALLOC_REG_SET (&reg_obstack);
1445 regs_live_at_setjmp = ALLOC_REG_SET (&reg_obstack);
1448 void
1449 allocate_reg_life_data (void)
1451 int i;
1453 max_regno = max_reg_num ();
1454 gcc_assert (!reg_deaths);
1455 reg_deaths = xcalloc (sizeof (*reg_deaths), max_regno);
1457 /* Recalculate the register space, in case it has grown. Old style
1458 vector oriented regsets would set regset_{size,bytes} here also. */
1459 allocate_reg_info (max_regno, FALSE, FALSE);
1461 /* Reset all the data we'll collect in propagate_block and its
1462 subroutines. */
1463 for (i = 0; i < max_regno; i++)
1465 REG_N_SETS (i) = 0;
1466 REG_N_REFS (i) = 0;
1467 REG_N_DEATHS (i) = 0;
1468 REG_N_CALLS_CROSSED (i) = 0;
1469 REG_LIVE_LENGTH (i) = 0;
1470 REG_FREQ (i) = 0;
1471 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
1475 /* Delete dead instructions for propagate_block. */
1477 static void
1478 propagate_block_delete_insn (rtx insn)
1480 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
1482 /* If the insn referred to a label, and that label was attached to
1483 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1484 pretty much mandatory to delete it, because the ADDR_VEC may be
1485 referencing labels that no longer exist.
1487 INSN may reference a deleted label, particularly when a jump
1488 table has been optimized into a direct jump. There's no
1489 real good way to fix up the reference to the deleted label
1490 when the label is deleted, so we just allow it here. */
1492 if (inote && LABEL_P (inote))
1494 rtx label = XEXP (inote, 0);
1495 rtx next;
1497 /* The label may be forced if it has been put in the constant
1498 pool. If that is the only use we must discard the table
1499 jump following it, but not the label itself. */
1500 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
1501 && (next = next_nonnote_insn (label)) != NULL
1502 && JUMP_P (next)
1503 && (GET_CODE (PATTERN (next)) == ADDR_VEC
1504 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
1506 rtx pat = PATTERN (next);
1507 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
1508 int len = XVECLEN (pat, diff_vec_p);
1509 int i;
1511 for (i = 0; i < len; i++)
1512 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
1514 delete_insn_and_edges (next);
1515 ndead++;
1519 delete_insn_and_edges (insn);
1520 ndead++;
1523 /* Delete dead libcalls for propagate_block. Return the insn
1524 before the libcall. */
1526 static rtx
1527 propagate_block_delete_libcall (rtx insn, rtx note)
1529 rtx first = XEXP (note, 0);
1530 rtx before = PREV_INSN (first);
1532 delete_insn_chain_and_edges (first, insn);
1533 ndead++;
1534 return before;
1537 /* Update the life-status of regs for one insn. Return the previous insn. */
1540 propagate_one_insn (struct propagate_block_info *pbi, rtx insn)
1542 rtx prev = PREV_INSN (insn);
1543 int flags = pbi->flags;
1544 int insn_is_dead = 0;
1545 int libcall_is_dead = 0;
1546 rtx note;
1547 unsigned i;
1549 if (! INSN_P (insn))
1550 return prev;
1552 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1553 if (flags & PROP_SCAN_DEAD_CODE)
1555 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
1556 libcall_is_dead = (insn_is_dead && note != 0
1557 && libcall_dead_p (pbi, note, insn));
1560 /* If an instruction consists of just dead store(s) on final pass,
1561 delete it. */
1562 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
1564 /* If we're trying to delete a prologue or epilogue instruction
1565 that isn't flagged as possibly being dead, something is wrong.
1566 But if we are keeping the stack pointer depressed, we might well
1567 be deleting insns that are used to compute the amount to update
1568 it by, so they are fine. */
1569 if (reload_completed
1570 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1571 && (TYPE_RETURNS_STACK_DEPRESSED
1572 (TREE_TYPE (current_function_decl))))
1573 && (((HAVE_epilogue || HAVE_prologue)
1574 && prologue_epilogue_contains (insn))
1575 || (HAVE_sibcall_epilogue
1576 && sibcall_epilogue_contains (insn)))
1577 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
1578 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn);
1580 /* Record sets. Do this even for dead instructions, since they
1581 would have killed the values if they hadn't been deleted. */
1582 mark_set_regs (pbi, PATTERN (insn), insn);
1584 /* CC0 is now known to be dead. Either this insn used it,
1585 in which case it doesn't anymore, or clobbered it,
1586 so the next insn can't use it. */
1587 pbi->cc0_live = 0;
1589 if (libcall_is_dead)
1590 prev = propagate_block_delete_libcall ( insn, note);
1591 else
1594 /* If INSN contains a RETVAL note and is dead, but the libcall
1595 as a whole is not dead, then we want to remove INSN, but
1596 not the whole libcall sequence.
1598 However, we need to also remove the dangling REG_LIBCALL
1599 note so that we do not have mis-matched LIBCALL/RETVAL
1600 notes. In theory we could find a new location for the
1601 REG_RETVAL note, but it hardly seems worth the effort.
1603 NOTE at this point will be the RETVAL note if it exists. */
1604 if (note)
1606 rtx libcall_note;
1608 libcall_note
1609 = find_reg_note (XEXP (note, 0), REG_LIBCALL, NULL_RTX);
1610 remove_note (XEXP (note, 0), libcall_note);
1613 /* Similarly if INSN contains a LIBCALL note, remove the
1614 dangling REG_RETVAL note. */
1615 note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
1616 if (note)
1618 rtx retval_note;
1620 retval_note
1621 = find_reg_note (XEXP (note, 0), REG_RETVAL, NULL_RTX);
1622 remove_note (XEXP (note, 0), retval_note);
1625 /* Now delete INSN. */
1626 propagate_block_delete_insn (insn);
1629 return prev;
1632 /* See if this is an increment or decrement that can be merged into
1633 a following memory address. */
1634 #ifdef AUTO_INC_DEC
1636 rtx x = single_set (insn);
1638 /* Does this instruction increment or decrement a register? */
1639 if ((flags & PROP_AUTOINC)
1640 && x != 0
1641 && REG_P (SET_DEST (x))
1642 && (GET_CODE (SET_SRC (x)) == PLUS
1643 || GET_CODE (SET_SRC (x)) == MINUS)
1644 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1645 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1646 /* Ok, look for a following memory ref we can combine with.
1647 If one is found, change the memory ref to a PRE_INC
1648 or PRE_DEC, cancel this insn, and return 1.
1649 Return 0 if nothing has been done. */
1650 && try_pre_increment_1 (pbi, insn))
1651 return prev;
1653 #endif /* AUTO_INC_DEC */
1655 CLEAR_REG_SET (pbi->new_set);
1657 /* If this is not the final pass, and this insn is copying the value of
1658 a library call and it's dead, don't scan the insns that perform the
1659 library call, so that the call's arguments are not marked live. */
1660 if (libcall_is_dead)
1662 /* Record the death of the dest reg. */
1663 mark_set_regs (pbi, PATTERN (insn), insn);
1665 insn = XEXP (note, 0);
1666 return PREV_INSN (insn);
1668 else if (GET_CODE (PATTERN (insn)) == SET
1669 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1670 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1671 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1672 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1674 /* We have an insn to pop a constant amount off the stack.
1675 (Such insns use PLUS regardless of the direction of the stack,
1676 and any insn to adjust the stack by a constant is always a pop
1677 or part of a push.)
1678 These insns, if not dead stores, have no effect on life, though
1679 they do have an effect on the memory stores we are tracking. */
1680 invalidate_mems_from_set (pbi, stack_pointer_rtx);
1681 /* Still, we need to update local_set, lest ifcvt.c:dead_or_predicable
1682 concludes that the stack pointer is not modified. */
1683 mark_set_regs (pbi, PATTERN (insn), insn);
1685 else
1687 rtx note;
1688 /* Any regs live at the time of a call instruction must not go
1689 in a register clobbered by calls. Find all regs now live and
1690 record this for them. */
1692 if (CALL_P (insn) && (flags & PROP_REG_INFO))
1694 reg_set_iterator rsi;
1695 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i, rsi)
1696 REG_N_CALLS_CROSSED (i)++;
1699 /* Record sets. Do this even for dead instructions, since they
1700 would have killed the values if they hadn't been deleted. */
1701 mark_set_regs (pbi, PATTERN (insn), insn);
1703 if (CALL_P (insn))
1705 regset live_at_end;
1706 bool sibcall_p;
1707 rtx note, cond;
1708 int i;
1710 cond = NULL_RTX;
1711 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1712 cond = COND_EXEC_TEST (PATTERN (insn));
1714 /* Non-constant calls clobber memory, constant calls do not
1715 clobber memory, though they may clobber outgoing arguments
1716 on the stack. */
1717 if (! CONST_OR_PURE_CALL_P (insn))
1719 free_EXPR_LIST_list (&pbi->mem_set_list);
1720 pbi->mem_set_list_len = 0;
1722 else
1723 invalidate_mems_from_set (pbi, stack_pointer_rtx);
1725 /* There may be extra registers to be clobbered. */
1726 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1727 note;
1728 note = XEXP (note, 1))
1729 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
1730 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
1731 cond, insn, pbi->flags);
1733 /* Calls change all call-used and global registers; sibcalls do not
1734 clobber anything that must be preserved at end-of-function,
1735 except for return values. */
1737 sibcall_p = SIBLING_CALL_P (insn);
1738 live_at_end = EXIT_BLOCK_PTR->global_live_at_start;
1739 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1740 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i)
1741 && ! (sibcall_p
1742 && REGNO_REG_SET_P (live_at_end, i)
1743 && ! refers_to_regno_p (i, i+1,
1744 current_function_return_rtx,
1745 (rtx *) 0)))
1747 enum rtx_code code = global_regs[i] ? SET : CLOBBER;
1748 /* We do not want REG_UNUSED notes for these registers. */
1749 mark_set_1 (pbi, code, regno_reg_rtx[i], cond, insn,
1750 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
1754 /* If an insn doesn't use CC0, it becomes dead since we assume
1755 that every insn clobbers it. So show it dead here;
1756 mark_used_regs will set it live if it is referenced. */
1757 pbi->cc0_live = 0;
1759 /* Record uses. */
1760 if (! insn_is_dead)
1761 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
1762 if ((flags & PROP_EQUAL_NOTES)
1763 && ((note = find_reg_note (insn, REG_EQUAL, NULL_RTX))
1764 || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX))))
1765 mark_used_regs (pbi, XEXP (note, 0), NULL_RTX, insn);
1767 /* Sometimes we may have inserted something before INSN (such as a move)
1768 when we make an auto-inc. So ensure we will scan those insns. */
1769 #ifdef AUTO_INC_DEC
1770 prev = PREV_INSN (insn);
1771 #endif
1773 if (! insn_is_dead && CALL_P (insn))
1775 int i;
1776 rtx note, cond;
1778 cond = NULL_RTX;
1779 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1780 cond = COND_EXEC_TEST (PATTERN (insn));
1782 /* Calls use their arguments, and may clobber memory which
1783 address involves some register. */
1784 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1785 note;
1786 note = XEXP (note, 1))
1787 /* We find USE or CLOBBER entities in a FUNCTION_USAGE list: both
1788 of which mark_used_regs knows how to handle. */
1789 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0), cond, insn);
1791 /* The stack ptr is used (honorarily) by a CALL insn. */
1792 if ((flags & PROP_REG_INFO)
1793 && !REGNO_REG_SET_P (pbi->reg_live, STACK_POINTER_REGNUM))
1794 reg_deaths[STACK_POINTER_REGNUM] = pbi->insn_num;
1795 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
1797 /* Calls may also reference any of the global registers,
1798 so they are made live. */
1799 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1800 if (global_regs[i])
1801 mark_used_reg (pbi, regno_reg_rtx[i], cond, insn);
1805 pbi->insn_num++;
1807 return prev;
1810 /* Initialize a propagate_block_info struct for public consumption.
1811 Note that the structure itself is opaque to this file, but that
1812 the user can use the regsets provided here. */
1814 struct propagate_block_info *
1815 init_propagate_block_info (basic_block bb, regset live, regset local_set,
1816 regset cond_local_set, int flags)
1818 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
1820 pbi->bb = bb;
1821 pbi->reg_live = live;
1822 pbi->mem_set_list = NULL_RTX;
1823 pbi->mem_set_list_len = 0;
1824 pbi->local_set = local_set;
1825 pbi->cond_local_set = cond_local_set;
1826 pbi->cc0_live = 0;
1827 pbi->flags = flags;
1828 pbi->insn_num = 0;
1830 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
1831 pbi->reg_next_use = xcalloc (max_reg_num (), sizeof (rtx));
1832 else
1833 pbi->reg_next_use = NULL;
1835 pbi->new_set = BITMAP_XMALLOC ();
1837 #ifdef HAVE_conditional_execution
1838 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
1839 free_reg_cond_life_info);
1840 pbi->reg_cond_reg = BITMAP_XMALLOC ();
1842 /* If this block ends in a conditional branch, for each register
1843 live from one side of the branch and not the other, record the
1844 register as conditionally dead. */
1845 if (JUMP_P (BB_END (bb))
1846 && any_condjump_p (BB_END (bb)))
1848 regset diff = ALLOC_REG_SET (&reg_obstack);
1849 basic_block bb_true, bb_false;
1850 unsigned i;
1852 /* Identify the successor blocks. */
1853 bb_true = EDGE_SUCC (bb, 0)->dest;
1854 if (EDGE_COUNT (bb->succs) > 1)
1856 bb_false = EDGE_SUCC (bb, 1)->dest;
1858 if (EDGE_SUCC (bb, 0)->flags & EDGE_FALLTHRU)
1860 basic_block t = bb_false;
1861 bb_false = bb_true;
1862 bb_true = t;
1864 else
1865 gcc_assert (EDGE_SUCC (bb, 1)->flags & EDGE_FALLTHRU);
1867 else
1869 /* This can happen with a conditional jump to the next insn. */
1870 gcc_assert (JUMP_LABEL (BB_END (bb)) == BB_HEAD (bb_true));
1872 /* Simplest way to do nothing. */
1873 bb_false = bb_true;
1876 /* Compute which register lead different lives in the successors. */
1877 bitmap_xor (diff, bb_true->global_live_at_start,
1878 bb_false->global_live_at_start);
1880 if (!bitmap_empty_p (diff))
1882 /* Extract the condition from the branch. */
1883 rtx set_src = SET_SRC (pc_set (BB_END (bb)));
1884 rtx cond_true = XEXP (set_src, 0);
1885 rtx reg = XEXP (cond_true, 0);
1886 enum rtx_code inv_cond;
1888 if (GET_CODE (reg) == SUBREG)
1889 reg = SUBREG_REG (reg);
1891 /* We can only track conditional lifetimes if the condition is
1892 in the form of a reversible comparison of a register against
1893 zero. If the condition is more complex than that, then it is
1894 safe not to record any information. */
1895 inv_cond = reversed_comparison_code (cond_true, BB_END (bb));
1896 if (inv_cond != UNKNOWN
1897 && REG_P (reg)
1898 && XEXP (cond_true, 1) == const0_rtx)
1900 rtx cond_false
1901 = gen_rtx_fmt_ee (inv_cond,
1902 GET_MODE (cond_true), XEXP (cond_true, 0),
1903 XEXP (cond_true, 1));
1904 reg_set_iterator rsi;
1906 if (GET_CODE (XEXP (set_src, 1)) == PC)
1908 rtx t = cond_false;
1909 cond_false = cond_true;
1910 cond_true = t;
1913 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
1915 /* For each such register, mark it conditionally dead. */
1916 EXECUTE_IF_SET_IN_REG_SET (diff, 0, i, rsi)
1918 struct reg_cond_life_info *rcli;
1919 rtx cond;
1921 rcli = xmalloc (sizeof (*rcli));
1923 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
1924 cond = cond_false;
1925 else
1926 cond = cond_true;
1927 rcli->condition = cond;
1928 rcli->stores = const0_rtx;
1929 rcli->orig_condition = cond;
1931 splay_tree_insert (pbi->reg_cond_dead, i,
1932 (splay_tree_value) rcli);
1937 FREE_REG_SET (diff);
1939 #endif
1941 /* If this block has no successors, any stores to the frame that aren't
1942 used later in the block are dead. So make a pass over the block
1943 recording any such that are made and show them dead at the end. We do
1944 a very conservative and simple job here. */
1945 if (optimize
1946 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1947 && (TYPE_RETURNS_STACK_DEPRESSED
1948 (TREE_TYPE (current_function_decl))))
1949 && (flags & PROP_SCAN_DEAD_STORES)
1950 && (EDGE_COUNT (bb->succs) == 0
1951 || (EDGE_COUNT (bb->succs) == 1
1952 && EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
1953 && ! current_function_calls_eh_return)))
1955 rtx insn, set;
1956 for (insn = BB_END (bb); insn != BB_HEAD (bb); insn = PREV_INSN (insn))
1957 if (NONJUMP_INSN_P (insn)
1958 && (set = single_set (insn))
1959 && MEM_P (SET_DEST (set)))
1961 rtx mem = SET_DEST (set);
1962 rtx canon_mem = canon_rtx (mem);
1964 if (XEXP (canon_mem, 0) == frame_pointer_rtx
1965 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
1966 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
1967 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
1968 add_to_mem_set_list (pbi, canon_mem);
1972 return pbi;
1975 /* Release a propagate_block_info struct. */
1977 void
1978 free_propagate_block_info (struct propagate_block_info *pbi)
1980 free_EXPR_LIST_list (&pbi->mem_set_list);
1982 BITMAP_XFREE (pbi->new_set);
1984 #ifdef HAVE_conditional_execution
1985 splay_tree_delete (pbi->reg_cond_dead);
1986 BITMAP_XFREE (pbi->reg_cond_reg);
1987 #endif
1989 if (pbi->flags & PROP_REG_INFO)
1991 int num = pbi->insn_num;
1992 unsigned i;
1993 reg_set_iterator rsi;
1995 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i, rsi)
1997 REG_LIVE_LENGTH (i) += num - reg_deaths[i];
1998 reg_deaths[i] = 0;
2001 if (pbi->reg_next_use)
2002 free (pbi->reg_next_use);
2004 free (pbi);
2007 /* Compute the registers live at the beginning of a basic block BB from
2008 those live at the end.
2010 When called, REG_LIVE contains those live at the end. On return, it
2011 contains those live at the beginning.
2013 LOCAL_SET, if non-null, will be set with all registers killed
2014 unconditionally by this basic block.
2015 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
2016 killed conditionally by this basic block. If there is any unconditional
2017 set of a register, then the corresponding bit will be set in LOCAL_SET
2018 and cleared in COND_LOCAL_SET.
2019 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
2020 case, the resulting set will be equal to the union of the two sets that
2021 would otherwise be computed.
2023 Return nonzero if an INSN is deleted (i.e. by dead code removal). */
2026 propagate_block (basic_block bb, regset live, regset local_set,
2027 regset cond_local_set, int flags)
2029 struct propagate_block_info *pbi;
2030 rtx insn, prev;
2031 int changed;
2033 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
2035 if (flags & PROP_REG_INFO)
2037 unsigned i;
2038 reg_set_iterator rsi;
2040 /* Process the regs live at the end of the block.
2041 Mark them as not local to any one basic block. */
2042 EXECUTE_IF_SET_IN_REG_SET (live, 0, i, rsi)
2043 REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL;
2046 /* Scan the block an insn at a time from end to beginning. */
2048 changed = 0;
2049 for (insn = BB_END (bb); ; insn = prev)
2051 /* If this is a call to `setjmp' et al, warn if any
2052 non-volatile datum is live. */
2053 if ((flags & PROP_REG_INFO)
2054 && CALL_P (insn)
2055 && find_reg_note (insn, REG_SETJMP, NULL))
2056 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
2058 prev = propagate_one_insn (pbi, insn);
2059 if (!prev)
2060 changed |= insn != get_insns ();
2061 else
2062 changed |= NEXT_INSN (prev) != insn;
2064 if (insn == BB_HEAD (bb))
2065 break;
2068 free_propagate_block_info (pbi);
2070 return changed;
2073 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2074 (SET expressions whose destinations are registers dead after the insn).
2075 NEEDED is the regset that says which regs are alive after the insn.
2077 Unless CALL_OK is nonzero, an insn is needed if it contains a CALL.
2079 If X is the entire body of an insn, NOTES contains the reg notes
2080 pertaining to the insn. */
2082 static int
2083 insn_dead_p (struct propagate_block_info *pbi, rtx x, int call_ok,
2084 rtx notes ATTRIBUTE_UNUSED)
2086 enum rtx_code code = GET_CODE (x);
2088 /* Don't eliminate insns that may trap. */
2089 if (flag_non_call_exceptions && may_trap_p (x))
2090 return 0;
2092 #ifdef AUTO_INC_DEC
2093 /* As flow is invoked after combine, we must take existing AUTO_INC
2094 expressions into account. */
2095 for (; notes; notes = XEXP (notes, 1))
2097 if (REG_NOTE_KIND (notes) == REG_INC)
2099 int regno = REGNO (XEXP (notes, 0));
2101 /* Don't delete insns to set global regs. */
2102 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2103 || REGNO_REG_SET_P (pbi->reg_live, regno))
2104 return 0;
2107 #endif
2109 /* If setting something that's a reg or part of one,
2110 see if that register's altered value will be live. */
2112 if (code == SET)
2114 rtx r = SET_DEST (x);
2116 #ifdef HAVE_cc0
2117 if (GET_CODE (r) == CC0)
2118 return ! pbi->cc0_live;
2119 #endif
2121 /* A SET that is a subroutine call cannot be dead. */
2122 if (GET_CODE (SET_SRC (x)) == CALL)
2124 if (! call_ok)
2125 return 0;
2128 /* Don't eliminate loads from volatile memory or volatile asms. */
2129 else if (volatile_refs_p (SET_SRC (x)))
2130 return 0;
2132 if (MEM_P (r))
2134 rtx temp, canon_r;
2136 if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode)
2137 return 0;
2139 canon_r = canon_rtx (r);
2141 /* Walk the set of memory locations we are currently tracking
2142 and see if one is an identical match to this memory location.
2143 If so, this memory write is dead (remember, we're walking
2144 backwards from the end of the block to the start). Since
2145 rtx_equal_p does not check the alias set or flags, we also
2146 must have the potential for them to conflict (anti_dependence). */
2147 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
2148 if (anti_dependence (r, XEXP (temp, 0)))
2150 rtx mem = XEXP (temp, 0);
2152 if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0))
2153 && (GET_MODE_SIZE (GET_MODE (canon_r))
2154 <= GET_MODE_SIZE (GET_MODE (mem))))
2155 return 1;
2157 #ifdef AUTO_INC_DEC
2158 /* Check if memory reference matches an auto increment. Only
2159 post increment/decrement or modify are valid. */
2160 if (GET_MODE (mem) == GET_MODE (r)
2161 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
2162 || GET_CODE (XEXP (mem, 0)) == POST_INC
2163 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
2164 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
2165 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
2166 return 1;
2167 #endif
2170 else
2172 while (GET_CODE (r) == SUBREG
2173 || GET_CODE (r) == STRICT_LOW_PART
2174 || GET_CODE (r) == ZERO_EXTRACT)
2175 r = XEXP (r, 0);
2177 if (REG_P (r))
2179 int regno = REGNO (r);
2181 /* Obvious. */
2182 if (REGNO_REG_SET_P (pbi->reg_live, regno))
2183 return 0;
2185 /* If this is a hard register, verify that subsequent
2186 words are not needed. */
2187 if (regno < FIRST_PSEUDO_REGISTER)
2189 int n = hard_regno_nregs[regno][GET_MODE (r)];
2191 while (--n > 0)
2192 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
2193 return 0;
2196 /* Don't delete insns to set global regs. */
2197 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2198 return 0;
2200 /* Make sure insns to set the stack pointer aren't deleted. */
2201 if (regno == STACK_POINTER_REGNUM)
2202 return 0;
2204 /* ??? These bits might be redundant with the force live bits
2205 in calculate_global_regs_live. We would delete from
2206 sequential sets; whether this actually affects real code
2207 for anything but the stack pointer I don't know. */
2208 /* Make sure insns to set the frame pointer aren't deleted. */
2209 if (regno == FRAME_POINTER_REGNUM
2210 && (! reload_completed || frame_pointer_needed))
2211 return 0;
2212 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2213 if (regno == HARD_FRAME_POINTER_REGNUM
2214 && (! reload_completed || frame_pointer_needed))
2215 return 0;
2216 #endif
2218 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2219 /* Make sure insns to set arg pointer are never deleted
2220 (if the arg pointer isn't fixed, there will be a USE
2221 for it, so we can treat it normally). */
2222 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2223 return 0;
2224 #endif
2226 /* Otherwise, the set is dead. */
2227 return 1;
2232 /* If performing several activities, insn is dead if each activity
2233 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2234 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2235 worth keeping. */
2236 else if (code == PARALLEL)
2238 int i = XVECLEN (x, 0);
2240 for (i--; i >= 0; i--)
2241 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
2242 && GET_CODE (XVECEXP (x, 0, i)) != USE
2243 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
2244 return 0;
2246 return 1;
2249 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2250 is not necessarily true for hard registers until after reload. */
2251 else if (code == CLOBBER)
2253 if (REG_P (XEXP (x, 0))
2254 && (REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
2255 || reload_completed)
2256 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
2257 return 1;
2260 /* ??? A base USE is a historical relic. It ought not be needed anymore.
2261 Instances where it is still used are either (1) temporary and the USE
2262 escaped the pass, (2) cruft and the USE need not be emitted anymore,
2263 or (3) hiding bugs elsewhere that are not properly representing data
2264 flow. */
2266 return 0;
2269 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2270 return 1 if the entire library call is dead.
2271 This is true if INSN copies a register (hard or pseudo)
2272 and if the hard return reg of the call insn is dead.
2273 (The caller should have tested the destination of the SET inside
2274 INSN already for death.)
2276 If this insn doesn't just copy a register, then we don't
2277 have an ordinary libcall. In that case, cse could not have
2278 managed to substitute the source for the dest later on,
2279 so we can assume the libcall is dead.
2281 PBI is the block info giving pseudoregs live before this insn.
2282 NOTE is the REG_RETVAL note of the insn. */
2284 static int
2285 libcall_dead_p (struct propagate_block_info *pbi, rtx note, rtx insn)
2287 rtx x = single_set (insn);
2289 if (x)
2291 rtx r = SET_SRC (x);
2293 if (REG_P (r))
2295 rtx call = XEXP (note, 0);
2296 rtx call_pat;
2297 int i;
2299 /* Find the call insn. */
2300 while (call != insn && !CALL_P (call))
2301 call = NEXT_INSN (call);
2303 /* If there is none, do nothing special,
2304 since ordinary death handling can understand these insns. */
2305 if (call == insn)
2306 return 0;
2308 /* See if the hard reg holding the value is dead.
2309 If this is a PARALLEL, find the call within it. */
2310 call_pat = PATTERN (call);
2311 if (GET_CODE (call_pat) == PARALLEL)
2313 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
2314 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
2315 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
2316 break;
2318 /* This may be a library call that is returning a value
2319 via invisible pointer. Do nothing special, since
2320 ordinary death handling can understand these insns. */
2321 if (i < 0)
2322 return 0;
2324 call_pat = XVECEXP (call_pat, 0, i);
2327 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
2330 return 1;
2333 /* 1 if register REGNO was alive at a place where `setjmp' was called
2334 and was set more than once or is an argument.
2335 Such regs may be clobbered by `longjmp'. */
2338 regno_clobbered_at_setjmp (int regno)
2340 if (n_basic_blocks == 0)
2341 return 0;
2343 return ((REG_N_SETS (regno) > 1
2344 || REGNO_REG_SET_P (ENTRY_BLOCK_PTR->global_live_at_end, regno))
2345 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
2348 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2349 maximal list size; look for overlaps in mode and select the largest. */
2350 static void
2351 add_to_mem_set_list (struct propagate_block_info *pbi, rtx mem)
2353 rtx i;
2355 /* We don't know how large a BLKmode store is, so we must not
2356 take them into consideration. */
2357 if (GET_MODE (mem) == BLKmode)
2358 return;
2360 for (i = pbi->mem_set_list; i ; i = XEXP (i, 1))
2362 rtx e = XEXP (i, 0);
2363 if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0)))
2365 if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e)))
2367 #ifdef AUTO_INC_DEC
2368 /* If we must store a copy of the mem, we can just modify
2369 the mode of the stored copy. */
2370 if (pbi->flags & PROP_AUTOINC)
2371 PUT_MODE (e, GET_MODE (mem));
2372 else
2373 #endif
2374 XEXP (i, 0) = mem;
2376 return;
2380 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN)
2382 #ifdef AUTO_INC_DEC
2383 /* Store a copy of mem, otherwise the address may be
2384 scrogged by find_auto_inc. */
2385 if (pbi->flags & PROP_AUTOINC)
2386 mem = shallow_copy_rtx (mem);
2387 #endif
2388 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
2389 pbi->mem_set_list_len++;
2393 /* INSN references memory, possibly using autoincrement addressing modes.
2394 Find any entries on the mem_set_list that need to be invalidated due
2395 to an address change. */
2397 static int
2398 invalidate_mems_from_autoinc (rtx *px, void *data)
2400 rtx x = *px;
2401 struct propagate_block_info *pbi = data;
2403 if (GET_RTX_CLASS (GET_CODE (x)) == RTX_AUTOINC)
2405 invalidate_mems_from_set (pbi, XEXP (x, 0));
2406 return -1;
2409 return 0;
2412 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2414 static void
2415 invalidate_mems_from_set (struct propagate_block_info *pbi, rtx exp)
2417 rtx temp = pbi->mem_set_list;
2418 rtx prev = NULL_RTX;
2419 rtx next;
2421 while (temp)
2423 next = XEXP (temp, 1);
2424 if (reg_overlap_mentioned_p (exp, XEXP (temp, 0)))
2426 /* Splice this entry out of the list. */
2427 if (prev)
2428 XEXP (prev, 1) = next;
2429 else
2430 pbi->mem_set_list = next;
2431 free_EXPR_LIST_node (temp);
2432 pbi->mem_set_list_len--;
2434 else
2435 prev = temp;
2436 temp = next;
2440 /* Process the registers that are set within X. Their bits are set to
2441 1 in the regset DEAD, because they are dead prior to this insn.
2443 If INSN is nonzero, it is the insn being processed.
2445 FLAGS is the set of operations to perform. */
2447 static void
2448 mark_set_regs (struct propagate_block_info *pbi, rtx x, rtx insn)
2450 rtx cond = NULL_RTX;
2451 rtx link;
2452 enum rtx_code code;
2453 int flags = pbi->flags;
2455 if (insn)
2456 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2458 if (REG_NOTE_KIND (link) == REG_INC)
2459 mark_set_1 (pbi, SET, XEXP (link, 0),
2460 (GET_CODE (x) == COND_EXEC
2461 ? COND_EXEC_TEST (x) : NULL_RTX),
2462 insn, flags);
2464 retry:
2465 switch (code = GET_CODE (x))
2467 case SET:
2468 if (GET_CODE (XEXP (x, 1)) == ASM_OPERANDS)
2469 flags |= PROP_ASM_SCAN;
2470 /* Fall through */
2471 case CLOBBER:
2472 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, flags);
2473 return;
2475 case COND_EXEC:
2476 cond = COND_EXEC_TEST (x);
2477 x = COND_EXEC_CODE (x);
2478 goto retry;
2480 case PARALLEL:
2482 int i;
2484 /* We must scan forwards. If we have an asm, we need to set
2485 the PROP_ASM_SCAN flag before scanning the clobbers. */
2486 for (i = 0; i < XVECLEN (x, 0); i++)
2488 rtx sub = XVECEXP (x, 0, i);
2489 switch (code = GET_CODE (sub))
2491 case COND_EXEC:
2492 gcc_assert (!cond);
2494 cond = COND_EXEC_TEST (sub);
2495 sub = COND_EXEC_CODE (sub);
2496 if (GET_CODE (sub) == SET)
2497 goto mark_set;
2498 if (GET_CODE (sub) == CLOBBER)
2499 goto mark_clob;
2500 break;
2502 case SET:
2503 mark_set:
2504 if (GET_CODE (XEXP (sub, 1)) == ASM_OPERANDS)
2505 flags |= PROP_ASM_SCAN;
2506 /* Fall through */
2507 case CLOBBER:
2508 mark_clob:
2509 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, flags);
2510 break;
2512 case ASM_OPERANDS:
2513 flags |= PROP_ASM_SCAN;
2514 break;
2516 default:
2517 break;
2520 break;
2523 default:
2524 break;
2528 /* Process a single set, which appears in INSN. REG (which may not
2529 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2530 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2531 If the set is conditional (because it appear in a COND_EXEC), COND
2532 will be the condition. */
2534 static void
2535 mark_set_1 (struct propagate_block_info *pbi, enum rtx_code code, rtx reg, rtx cond, rtx insn, int flags)
2537 int regno_first = -1, regno_last = -1;
2538 unsigned long not_dead = 0;
2539 int i;
2541 /* Modifying just one hardware register of a multi-reg value or just a
2542 byte field of a register does not mean the value from before this insn
2543 is now dead. Of course, if it was dead after it's unused now. */
2545 switch (GET_CODE (reg))
2547 case PARALLEL:
2548 /* Some targets place small structures in registers for return values of
2549 functions. We have to detect this case specially here to get correct
2550 flow information. */
2551 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
2552 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
2553 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
2554 flags);
2555 return;
2557 case ZERO_EXTRACT:
2558 case SIGN_EXTRACT:
2559 case STRICT_LOW_PART:
2560 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2562 reg = XEXP (reg, 0);
2563 while (GET_CODE (reg) == SUBREG
2564 || GET_CODE (reg) == ZERO_EXTRACT
2565 || GET_CODE (reg) == SIGN_EXTRACT
2566 || GET_CODE (reg) == STRICT_LOW_PART);
2567 if (MEM_P (reg))
2568 break;
2569 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
2570 /* Fall through. */
2572 case REG:
2573 regno_last = regno_first = REGNO (reg);
2574 if (regno_first < FIRST_PSEUDO_REGISTER)
2575 regno_last += hard_regno_nregs[regno_first][GET_MODE (reg)] - 1;
2576 break;
2578 case SUBREG:
2579 if (REG_P (SUBREG_REG (reg)))
2581 enum machine_mode outer_mode = GET_MODE (reg);
2582 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
2584 /* Identify the range of registers affected. This is moderately
2585 tricky for hard registers. See alter_subreg. */
2587 regno_last = regno_first = REGNO (SUBREG_REG (reg));
2588 if (regno_first < FIRST_PSEUDO_REGISTER)
2590 regno_first += subreg_regno_offset (regno_first, inner_mode,
2591 SUBREG_BYTE (reg),
2592 outer_mode);
2593 regno_last = (regno_first
2594 + hard_regno_nregs[regno_first][outer_mode] - 1);
2596 /* Since we've just adjusted the register number ranges, make
2597 sure REG matches. Otherwise some_was_live will be clear
2598 when it shouldn't have been, and we'll create incorrect
2599 REG_UNUSED notes. */
2600 reg = gen_rtx_REG (outer_mode, regno_first);
2602 else
2604 /* If the number of words in the subreg is less than the number
2605 of words in the full register, we have a well-defined partial
2606 set. Otherwise the high bits are undefined.
2608 This is only really applicable to pseudos, since we just took
2609 care of multi-word hard registers. */
2610 if (((GET_MODE_SIZE (outer_mode)
2611 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
2612 < ((GET_MODE_SIZE (inner_mode)
2613 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
2614 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
2615 regno_first);
2617 reg = SUBREG_REG (reg);
2620 else
2621 reg = SUBREG_REG (reg);
2622 break;
2624 default:
2625 break;
2628 /* If this set is a MEM, then it kills any aliased writes.
2629 If this set is a REG, then it kills any MEMs which use the reg. */
2630 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
2632 if (REG_P (reg))
2633 invalidate_mems_from_set (pbi, reg);
2635 /* If the memory reference had embedded side effects (autoincrement
2636 address modes) then we may need to kill some entries on the
2637 memory set list. */
2638 if (insn && MEM_P (reg))
2639 for_each_rtx (&PATTERN (insn), invalidate_mems_from_autoinc, pbi);
2641 if (MEM_P (reg) && ! side_effects_p (reg)
2642 /* ??? With more effort we could track conditional memory life. */
2643 && ! cond)
2644 add_to_mem_set_list (pbi, canon_rtx (reg));
2647 if (REG_P (reg)
2648 && ! (regno_first == FRAME_POINTER_REGNUM
2649 && (! reload_completed || frame_pointer_needed))
2650 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2651 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
2652 && (! reload_completed || frame_pointer_needed))
2653 #endif
2654 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2655 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
2656 #endif
2659 int some_was_live = 0, some_was_dead = 0;
2661 for (i = regno_first; i <= regno_last; ++i)
2663 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
2664 if (pbi->local_set)
2666 /* Order of the set operation matters here since both
2667 sets may be the same. */
2668 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
2669 if (cond != NULL_RTX
2670 && ! REGNO_REG_SET_P (pbi->local_set, i))
2671 SET_REGNO_REG_SET (pbi->cond_local_set, i);
2672 else
2673 SET_REGNO_REG_SET (pbi->local_set, i);
2675 if (code != CLOBBER)
2676 SET_REGNO_REG_SET (pbi->new_set, i);
2678 some_was_live |= needed_regno;
2679 some_was_dead |= ! needed_regno;
2682 #ifdef HAVE_conditional_execution
2683 /* Consider conditional death in deciding that the register needs
2684 a death note. */
2685 if (some_was_live && ! not_dead
2686 /* The stack pointer is never dead. Well, not strictly true,
2687 but it's very difficult to tell from here. Hopefully
2688 combine_stack_adjustments will fix up the most egregious
2689 errors. */
2690 && regno_first != STACK_POINTER_REGNUM)
2692 for (i = regno_first; i <= regno_last; ++i)
2693 if (! mark_regno_cond_dead (pbi, i, cond))
2694 not_dead |= ((unsigned long) 1) << (i - regno_first);
2696 #endif
2698 /* Additional data to record if this is the final pass. */
2699 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
2700 | PROP_DEATH_NOTES | PROP_AUTOINC))
2702 rtx y;
2703 int blocknum = pbi->bb->index;
2705 y = NULL_RTX;
2706 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2708 y = pbi->reg_next_use[regno_first];
2710 /* The next use is no longer next, since a store intervenes. */
2711 for (i = regno_first; i <= regno_last; ++i)
2712 pbi->reg_next_use[i] = 0;
2715 if (flags & PROP_REG_INFO)
2717 for (i = regno_first; i <= regno_last; ++i)
2719 /* Count (weighted) references, stores, etc. This counts a
2720 register twice if it is modified, but that is correct. */
2721 REG_N_SETS (i) += 1;
2722 REG_N_REFS (i) += 1;
2723 REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb);
2725 /* The insns where a reg is live are normally counted
2726 elsewhere, but we want the count to include the insn
2727 where the reg is set, and the normal counting mechanism
2728 would not count it. */
2729 REG_LIVE_LENGTH (i) += 1;
2732 /* If this is a hard reg, record this function uses the reg. */
2733 if (regno_first < FIRST_PSEUDO_REGISTER)
2735 for (i = regno_first; i <= regno_last; i++)
2736 regs_ever_live[i] = 1;
2737 if (flags & PROP_ASM_SCAN)
2738 for (i = regno_first; i <= regno_last; i++)
2739 regs_asm_clobbered[i] = 1;
2741 else
2743 /* Keep track of which basic blocks each reg appears in. */
2744 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
2745 REG_BASIC_BLOCK (regno_first) = blocknum;
2746 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
2747 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
2751 if (! some_was_dead)
2753 if (flags & PROP_LOG_LINKS)
2755 /* Make a logical link from the next following insn
2756 that uses this register, back to this insn.
2757 The following insns have already been processed.
2759 We don't build a LOG_LINK for hard registers containing
2760 in ASM_OPERANDs. If these registers get replaced,
2761 we might wind up changing the semantics of the insn,
2762 even if reload can make what appear to be valid
2763 assignments later.
2765 We don't build a LOG_LINK for global registers to
2766 or from a function call. We don't want to let
2767 combine think that it knows what is going on with
2768 global registers. */
2769 if (y && (BLOCK_NUM (y) == blocknum)
2770 && (regno_first >= FIRST_PSEUDO_REGISTER
2771 || (asm_noperands (PATTERN (y)) < 0
2772 && ! ((CALL_P (insn)
2773 || CALL_P (y))
2774 && global_regs[regno_first]))))
2775 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
2778 else if (not_dead)
2780 else if (! some_was_live)
2782 if (flags & PROP_REG_INFO)
2783 REG_N_DEATHS (regno_first) += 1;
2785 if (flags & PROP_DEATH_NOTES)
2787 /* Note that dead stores have already been deleted
2788 when possible. If we get here, we have found a
2789 dead store that cannot be eliminated (because the
2790 same insn does something useful). Indicate this
2791 by marking the reg being set as dying here. */
2792 REG_NOTES (insn)
2793 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2796 else
2798 if (flags & PROP_DEATH_NOTES)
2800 /* This is a case where we have a multi-word hard register
2801 and some, but not all, of the words of the register are
2802 needed in subsequent insns. Write REG_UNUSED notes
2803 for those parts that were not needed. This case should
2804 be rare. */
2806 for (i = regno_first; i <= regno_last; ++i)
2807 if (! REGNO_REG_SET_P (pbi->reg_live, i))
2808 REG_NOTES (insn)
2809 = alloc_EXPR_LIST (REG_UNUSED,
2810 regno_reg_rtx[i],
2811 REG_NOTES (insn));
2816 /* Mark the register as being dead. */
2817 if (some_was_live
2818 /* The stack pointer is never dead. Well, not strictly true,
2819 but it's very difficult to tell from here. Hopefully
2820 combine_stack_adjustments will fix up the most egregious
2821 errors. */
2822 && regno_first != STACK_POINTER_REGNUM)
2824 for (i = regno_first; i <= regno_last; ++i)
2825 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
2827 if ((pbi->flags & PROP_REG_INFO)
2828 && REGNO_REG_SET_P (pbi->reg_live, i))
2830 REG_LIVE_LENGTH (i) += pbi->insn_num - reg_deaths[i];
2831 reg_deaths[i] = 0;
2833 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
2837 else if (REG_P (reg))
2839 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2840 pbi->reg_next_use[regno_first] = 0;
2842 if ((flags & PROP_REG_INFO) != 0
2843 && (flags & PROP_ASM_SCAN) != 0
2844 && regno_first < FIRST_PSEUDO_REGISTER)
2846 for (i = regno_first; i <= regno_last; i++)
2847 regs_asm_clobbered[i] = 1;
2851 /* If this is the last pass and this is a SCRATCH, show it will be dying
2852 here and count it. */
2853 else if (GET_CODE (reg) == SCRATCH)
2855 if (flags & PROP_DEATH_NOTES)
2856 REG_NOTES (insn)
2857 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2861 #ifdef HAVE_conditional_execution
2862 /* Mark REGNO conditionally dead.
2863 Return true if the register is now unconditionally dead. */
2865 static int
2866 mark_regno_cond_dead (struct propagate_block_info *pbi, int regno, rtx cond)
2868 /* If this is a store to a predicate register, the value of the
2869 predicate is changing, we don't know that the predicate as seen
2870 before is the same as that seen after. Flush all dependent
2871 conditions from reg_cond_dead. This will make all such
2872 conditionally live registers unconditionally live. */
2873 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
2874 flush_reg_cond_reg (pbi, regno);
2876 /* If this is an unconditional store, remove any conditional
2877 life that may have existed. */
2878 if (cond == NULL_RTX)
2879 splay_tree_remove (pbi->reg_cond_dead, regno);
2880 else
2882 splay_tree_node node;
2883 struct reg_cond_life_info *rcli;
2884 rtx ncond;
2886 /* Otherwise this is a conditional set. Record that fact.
2887 It may have been conditionally used, or there may be a
2888 subsequent set with a complimentary condition. */
2890 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
2891 if (node == NULL)
2893 /* The register was unconditionally live previously.
2894 Record the current condition as the condition under
2895 which it is dead. */
2896 rcli = xmalloc (sizeof (*rcli));
2897 rcli->condition = cond;
2898 rcli->stores = cond;
2899 rcli->orig_condition = const0_rtx;
2900 splay_tree_insert (pbi->reg_cond_dead, regno,
2901 (splay_tree_value) rcli);
2903 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2905 /* Not unconditionally dead. */
2906 return 0;
2908 else
2910 /* The register was conditionally live previously.
2911 Add the new condition to the old. */
2912 rcli = (struct reg_cond_life_info *) node->value;
2913 ncond = rcli->condition;
2914 ncond = ior_reg_cond (ncond, cond, 1);
2915 if (rcli->stores == const0_rtx)
2916 rcli->stores = cond;
2917 else if (rcli->stores != const1_rtx)
2918 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
2920 /* If the register is now unconditionally dead, remove the entry
2921 in the splay_tree. A register is unconditionally dead if the
2922 dead condition ncond is true. A register is also unconditionally
2923 dead if the sum of all conditional stores is an unconditional
2924 store (stores is true), and the dead condition is identically the
2925 same as the original dead condition initialized at the end of
2926 the block. This is a pointer compare, not an rtx_equal_p
2927 compare. */
2928 if (ncond == const1_rtx
2929 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
2930 splay_tree_remove (pbi->reg_cond_dead, regno);
2931 else
2933 rcli->condition = ncond;
2935 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2937 /* Not unconditionally dead. */
2938 return 0;
2943 return 1;
2946 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2948 static void
2949 free_reg_cond_life_info (splay_tree_value value)
2951 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
2952 free (rcli);
2955 /* Helper function for flush_reg_cond_reg. */
2957 static int
2958 flush_reg_cond_reg_1 (splay_tree_node node, void *data)
2960 struct reg_cond_life_info *rcli;
2961 int *xdata = (int *) data;
2962 unsigned int regno = xdata[0];
2964 /* Don't need to search if last flushed value was farther on in
2965 the in-order traversal. */
2966 if (xdata[1] >= (int) node->key)
2967 return 0;
2969 /* Splice out portions of the expression that refer to regno. */
2970 rcli = (struct reg_cond_life_info *) node->value;
2971 rcli->condition = elim_reg_cond (rcli->condition, regno);
2972 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
2973 rcli->stores = elim_reg_cond (rcli->stores, regno);
2975 /* If the entire condition is now false, signal the node to be removed. */
2976 if (rcli->condition == const0_rtx)
2978 xdata[1] = node->key;
2979 return -1;
2981 else
2982 gcc_assert (rcli->condition != const1_rtx);
2984 return 0;
2987 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2989 static void
2990 flush_reg_cond_reg (struct propagate_block_info *pbi, int regno)
2992 int pair[2];
2994 pair[0] = regno;
2995 pair[1] = -1;
2996 while (splay_tree_foreach (pbi->reg_cond_dead,
2997 flush_reg_cond_reg_1, pair) == -1)
2998 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
3000 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
3003 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
3004 For ior/and, the ADD flag determines whether we want to add the new
3005 condition X to the old one unconditionally. If it is zero, we will
3006 only return a new expression if X allows us to simplify part of
3007 OLD, otherwise we return NULL to the caller.
3008 If ADD is nonzero, we will return a new condition in all cases. The
3009 toplevel caller of one of these functions should always pass 1 for
3010 ADD. */
3012 static rtx
3013 ior_reg_cond (rtx old, rtx x, int add)
3015 rtx op0, op1;
3017 if (COMPARISON_P (old))
3019 if (COMPARISON_P (x)
3020 && REVERSE_CONDEXEC_PREDICATES_P (x, old)
3021 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3022 return const1_rtx;
3023 if (GET_CODE (x) == GET_CODE (old)
3024 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3025 return old;
3026 if (! add)
3027 return NULL;
3028 return gen_rtx_IOR (0, old, x);
3031 switch (GET_CODE (old))
3033 case IOR:
3034 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3035 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3036 if (op0 != NULL || op1 != NULL)
3038 if (op0 == const0_rtx)
3039 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3040 if (op1 == const0_rtx)
3041 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3042 if (op0 == const1_rtx || op1 == const1_rtx)
3043 return const1_rtx;
3044 if (op0 == NULL)
3045 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3046 else if (rtx_equal_p (x, op0))
3047 /* (x | A) | x ~ (x | A). */
3048 return old;
3049 if (op1 == NULL)
3050 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3051 else if (rtx_equal_p (x, op1))
3052 /* (A | x) | x ~ (A | x). */
3053 return old;
3054 return gen_rtx_IOR (0, op0, op1);
3056 if (! add)
3057 return NULL;
3058 return gen_rtx_IOR (0, old, x);
3060 case AND:
3061 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3062 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3063 if (op0 != NULL || op1 != NULL)
3065 if (op0 == const1_rtx)
3066 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3067 if (op1 == const1_rtx)
3068 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3069 if (op0 == const0_rtx || op1 == const0_rtx)
3070 return const0_rtx;
3071 if (op0 == NULL)
3072 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3073 else if (rtx_equal_p (x, op0))
3074 /* (x & A) | x ~ x. */
3075 return op0;
3076 if (op1 == NULL)
3077 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3078 else if (rtx_equal_p (x, op1))
3079 /* (A & x) | x ~ x. */
3080 return op1;
3081 return gen_rtx_AND (0, op0, op1);
3083 if (! add)
3084 return NULL;
3085 return gen_rtx_IOR (0, old, x);
3087 case NOT:
3088 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3089 if (op0 != NULL)
3090 return not_reg_cond (op0);
3091 if (! add)
3092 return NULL;
3093 return gen_rtx_IOR (0, old, x);
3095 default:
3096 gcc_unreachable ();
3100 static rtx
3101 not_reg_cond (rtx x)
3103 if (x == const0_rtx)
3104 return const1_rtx;
3105 else if (x == const1_rtx)
3106 return const0_rtx;
3107 if (GET_CODE (x) == NOT)
3108 return XEXP (x, 0);
3109 if (COMPARISON_P (x)
3110 && REG_P (XEXP (x, 0)))
3112 gcc_assert (XEXP (x, 1) == const0_rtx);
3114 return gen_rtx_fmt_ee (reversed_comparison_code (x, NULL),
3115 VOIDmode, XEXP (x, 0), const0_rtx);
3117 return gen_rtx_NOT (0, x);
3120 static rtx
3121 and_reg_cond (rtx old, rtx x, int add)
3123 rtx op0, op1;
3125 if (COMPARISON_P (old))
3127 if (COMPARISON_P (x)
3128 && GET_CODE (x) == reversed_comparison_code (old, NULL)
3129 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3130 return const0_rtx;
3131 if (GET_CODE (x) == GET_CODE (old)
3132 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3133 return old;
3134 if (! add)
3135 return NULL;
3136 return gen_rtx_AND (0, old, x);
3139 switch (GET_CODE (old))
3141 case IOR:
3142 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3143 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3144 if (op0 != NULL || op1 != NULL)
3146 if (op0 == const0_rtx)
3147 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3148 if (op1 == const0_rtx)
3149 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3150 if (op0 == const1_rtx || op1 == const1_rtx)
3151 return const1_rtx;
3152 if (op0 == NULL)
3153 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3154 else if (rtx_equal_p (x, op0))
3155 /* (x | A) & x ~ x. */
3156 return op0;
3157 if (op1 == NULL)
3158 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3159 else if (rtx_equal_p (x, op1))
3160 /* (A | x) & x ~ x. */
3161 return op1;
3162 return gen_rtx_IOR (0, op0, op1);
3164 if (! add)
3165 return NULL;
3166 return gen_rtx_AND (0, old, x);
3168 case AND:
3169 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3170 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3171 if (op0 != NULL || op1 != NULL)
3173 if (op0 == const1_rtx)
3174 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3175 if (op1 == const1_rtx)
3176 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3177 if (op0 == const0_rtx || op1 == const0_rtx)
3178 return const0_rtx;
3179 if (op0 == NULL)
3180 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3181 else if (rtx_equal_p (x, op0))
3182 /* (x & A) & x ~ (x & A). */
3183 return old;
3184 if (op1 == NULL)
3185 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3186 else if (rtx_equal_p (x, op1))
3187 /* (A & x) & x ~ (A & x). */
3188 return old;
3189 return gen_rtx_AND (0, op0, op1);
3191 if (! add)
3192 return NULL;
3193 return gen_rtx_AND (0, old, x);
3195 case NOT:
3196 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3197 if (op0 != NULL)
3198 return not_reg_cond (op0);
3199 if (! add)
3200 return NULL;
3201 return gen_rtx_AND (0, old, x);
3203 default:
3204 gcc_unreachable ();
3208 /* Given a condition X, remove references to reg REGNO and return the
3209 new condition. The removal will be done so that all conditions
3210 involving REGNO are considered to evaluate to false. This function
3211 is used when the value of REGNO changes. */
3213 static rtx
3214 elim_reg_cond (rtx x, unsigned int regno)
3216 rtx op0, op1;
3218 if (COMPARISON_P (x))
3220 if (REGNO (XEXP (x, 0)) == regno)
3221 return const0_rtx;
3222 return x;
3225 switch (GET_CODE (x))
3227 case AND:
3228 op0 = elim_reg_cond (XEXP (x, 0), regno);
3229 op1 = elim_reg_cond (XEXP (x, 1), regno);
3230 if (op0 == const0_rtx || op1 == const0_rtx)
3231 return const0_rtx;
3232 if (op0 == const1_rtx)
3233 return op1;
3234 if (op1 == const1_rtx)
3235 return op0;
3236 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3237 return x;
3238 return gen_rtx_AND (0, op0, op1);
3240 case IOR:
3241 op0 = elim_reg_cond (XEXP (x, 0), regno);
3242 op1 = elim_reg_cond (XEXP (x, 1), regno);
3243 if (op0 == const1_rtx || op1 == const1_rtx)
3244 return const1_rtx;
3245 if (op0 == const0_rtx)
3246 return op1;
3247 if (op1 == const0_rtx)
3248 return op0;
3249 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3250 return x;
3251 return gen_rtx_IOR (0, op0, op1);
3253 case NOT:
3254 op0 = elim_reg_cond (XEXP (x, 0), regno);
3255 if (op0 == const0_rtx)
3256 return const1_rtx;
3257 if (op0 == const1_rtx)
3258 return const0_rtx;
3259 if (op0 != XEXP (x, 0))
3260 return not_reg_cond (op0);
3261 return x;
3263 default:
3264 gcc_unreachable ();
3267 #endif /* HAVE_conditional_execution */
3269 #ifdef AUTO_INC_DEC
3271 /* Try to substitute the auto-inc expression INC as the address inside
3272 MEM which occurs in INSN. Currently, the address of MEM is an expression
3273 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3274 that has a single set whose source is a PLUS of INCR_REG and something
3275 else. */
3277 static void
3278 attempt_auto_inc (struct propagate_block_info *pbi, rtx inc, rtx insn,
3279 rtx mem, rtx incr, rtx incr_reg)
3281 int regno = REGNO (incr_reg);
3282 rtx set = single_set (incr);
3283 rtx q = SET_DEST (set);
3284 rtx y = SET_SRC (set);
3285 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
3286 int changed;
3288 /* Make sure this reg appears only once in this insn. */
3289 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
3290 return;
3292 if (dead_or_set_p (incr, incr_reg)
3293 /* Mustn't autoinc an eliminable register. */
3294 && (regno >= FIRST_PSEUDO_REGISTER
3295 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
3297 /* This is the simple case. Try to make the auto-inc. If
3298 we can't, we are done. Otherwise, we will do any
3299 needed updates below. */
3300 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
3301 return;
3303 else if (REG_P (q)
3304 /* PREV_INSN used here to check the semi-open interval
3305 [insn,incr). */
3306 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
3307 /* We must also check for sets of q as q may be
3308 a call clobbered hard register and there may
3309 be a call between PREV_INSN (insn) and incr. */
3310 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
3312 /* We have *p followed sometime later by q = p+size.
3313 Both p and q must be live afterward,
3314 and q is not used between INSN and its assignment.
3315 Change it to q = p, ...*q..., q = q+size.
3316 Then fall into the usual case. */
3317 rtx insns, temp;
3319 start_sequence ();
3320 emit_move_insn (q, incr_reg);
3321 insns = get_insns ();
3322 end_sequence ();
3324 /* If we can't make the auto-inc, or can't make the
3325 replacement into Y, exit. There's no point in making
3326 the change below if we can't do the auto-inc and doing
3327 so is not correct in the pre-inc case. */
3329 XEXP (inc, 0) = q;
3330 validate_change (insn, &XEXP (mem, 0), inc, 1);
3331 validate_change (incr, &XEXP (y, opnum), q, 1);
3332 if (! apply_change_group ())
3333 return;
3335 /* We now know we'll be doing this change, so emit the
3336 new insn(s) and do the updates. */
3337 emit_insn_before (insns, insn);
3339 if (BB_HEAD (pbi->bb) == insn)
3340 BB_HEAD (pbi->bb) = insns;
3342 /* INCR will become a NOTE and INSN won't contain a
3343 use of INCR_REG. If a use of INCR_REG was just placed in
3344 the insn before INSN, make that the next use.
3345 Otherwise, invalidate it. */
3346 if (NONJUMP_INSN_P (PREV_INSN (insn))
3347 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
3348 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
3349 pbi->reg_next_use[regno] = PREV_INSN (insn);
3350 else
3351 pbi->reg_next_use[regno] = 0;
3353 incr_reg = q;
3354 regno = REGNO (q);
3356 if ((pbi->flags & PROP_REG_INFO)
3357 && !REGNO_REG_SET_P (pbi->reg_live, regno))
3358 reg_deaths[regno] = pbi->insn_num;
3360 /* REGNO is now used in INCR which is below INSN, but
3361 it previously wasn't live here. If we don't mark
3362 it as live, we'll put a REG_DEAD note for it
3363 on this insn, which is incorrect. */
3364 SET_REGNO_REG_SET (pbi->reg_live, regno);
3366 /* If there are any calls between INSN and INCR, show
3367 that REGNO now crosses them. */
3368 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
3369 if (CALL_P (temp))
3370 REG_N_CALLS_CROSSED (regno)++;
3372 /* Invalidate alias info for Q since we just changed its value. */
3373 clear_reg_alias_info (q);
3375 else
3376 return;
3378 /* If we haven't returned, it means we were able to make the
3379 auto-inc, so update the status. First, record that this insn
3380 has an implicit side effect. */
3382 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
3384 /* Modify the old increment-insn to simply copy
3385 the already-incremented value of our register. */
3386 changed = validate_change (incr, &SET_SRC (set), incr_reg, 0);
3387 gcc_assert (changed);
3389 /* If that makes it a no-op (copying the register into itself) delete
3390 it so it won't appear to be a "use" and a "set" of this
3391 register. */
3392 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
3394 /* If the original source was dead, it's dead now. */
3395 rtx note;
3397 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
3399 remove_note (incr, note);
3400 if (XEXP (note, 0) != incr_reg)
3402 unsigned int regno = REGNO (XEXP (note, 0));
3404 if ((pbi->flags & PROP_REG_INFO)
3405 && REGNO_REG_SET_P (pbi->reg_live, regno))
3407 REG_LIVE_LENGTH (regno) += pbi->insn_num - reg_deaths[regno];
3408 reg_deaths[regno] = 0;
3410 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
3414 SET_INSN_DELETED (incr);
3417 if (regno >= FIRST_PSEUDO_REGISTER)
3419 /* Count an extra reference to the reg. When a reg is
3420 incremented, spilling it is worse, so we want to make
3421 that less likely. */
3422 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3424 /* Count the increment as a setting of the register,
3425 even though it isn't a SET in rtl. */
3426 REG_N_SETS (regno)++;
3430 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3431 reference. */
3433 static void
3434 find_auto_inc (struct propagate_block_info *pbi, rtx x, rtx insn)
3436 rtx addr = XEXP (x, 0);
3437 HOST_WIDE_INT offset = 0;
3438 rtx set, y, incr, inc_val;
3439 int regno;
3440 int size = GET_MODE_SIZE (GET_MODE (x));
3442 if (JUMP_P (insn))
3443 return;
3445 /* Here we detect use of an index register which might be good for
3446 postincrement, postdecrement, preincrement, or predecrement. */
3448 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
3449 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
3451 if (!REG_P (addr))
3452 return;
3454 regno = REGNO (addr);
3456 /* Is the next use an increment that might make auto-increment? */
3457 incr = pbi->reg_next_use[regno];
3458 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
3459 return;
3460 set = single_set (incr);
3461 if (set == 0 || GET_CODE (set) != SET)
3462 return;
3463 y = SET_SRC (set);
3465 if (GET_CODE (y) != PLUS)
3466 return;
3468 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
3469 inc_val = XEXP (y, 1);
3470 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
3471 inc_val = XEXP (y, 0);
3472 else
3473 return;
3475 if (GET_CODE (inc_val) == CONST_INT)
3477 if (HAVE_POST_INCREMENT
3478 && (INTVAL (inc_val) == size && offset == 0))
3479 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
3480 incr, addr);
3481 else if (HAVE_POST_DECREMENT
3482 && (INTVAL (inc_val) == -size && offset == 0))
3483 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
3484 incr, addr);
3485 else if (HAVE_PRE_INCREMENT
3486 && (INTVAL (inc_val) == size && offset == size))
3487 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
3488 incr, addr);
3489 else if (HAVE_PRE_DECREMENT
3490 && (INTVAL (inc_val) == -size && offset == -size))
3491 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
3492 incr, addr);
3493 else if (HAVE_POST_MODIFY_DISP && offset == 0)
3494 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3495 gen_rtx_PLUS (Pmode,
3496 addr,
3497 inc_val)),
3498 insn, x, incr, addr);
3499 else if (HAVE_PRE_MODIFY_DISP && offset == INTVAL (inc_val))
3500 attempt_auto_inc (pbi, gen_rtx_PRE_MODIFY (Pmode, addr,
3501 gen_rtx_PLUS (Pmode,
3502 addr,
3503 inc_val)),
3504 insn, x, incr, addr);
3506 else if (REG_P (inc_val)
3507 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
3508 NEXT_INSN (incr)))
3511 if (HAVE_POST_MODIFY_REG && offset == 0)
3512 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3513 gen_rtx_PLUS (Pmode,
3514 addr,
3515 inc_val)),
3516 insn, x, incr, addr);
3520 #endif /* AUTO_INC_DEC */
3522 static void
3523 mark_used_reg (struct propagate_block_info *pbi, rtx reg,
3524 rtx cond ATTRIBUTE_UNUSED, rtx insn)
3526 unsigned int regno_first, regno_last, i;
3527 int some_was_live, some_was_dead, some_not_set;
3529 regno_last = regno_first = REGNO (reg);
3530 if (regno_first < FIRST_PSEUDO_REGISTER)
3531 regno_last += hard_regno_nregs[regno_first][GET_MODE (reg)] - 1;
3533 /* Find out if any of this register is live after this instruction. */
3534 some_was_live = some_was_dead = 0;
3535 for (i = regno_first; i <= regno_last; ++i)
3537 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
3538 some_was_live |= needed_regno;
3539 some_was_dead |= ! needed_regno;
3542 /* Find out if any of the register was set this insn. */
3543 some_not_set = 0;
3544 for (i = regno_first; i <= regno_last; ++i)
3545 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
3547 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3549 /* Record where each reg is used, so when the reg is set we know
3550 the next insn that uses it. */
3551 pbi->reg_next_use[regno_first] = insn;
3554 if (pbi->flags & PROP_REG_INFO)
3556 if (regno_first < FIRST_PSEUDO_REGISTER)
3558 /* If this is a register we are going to try to eliminate,
3559 don't mark it live here. If we are successful in
3560 eliminating it, it need not be live unless it is used for
3561 pseudos, in which case it will have been set live when it
3562 was allocated to the pseudos. If the register will not
3563 be eliminated, reload will set it live at that point.
3565 Otherwise, record that this function uses this register. */
3566 /* ??? The PPC backend tries to "eliminate" on the pic
3567 register to itself. This should be fixed. In the mean
3568 time, hack around it. */
3570 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
3571 && (regno_first == FRAME_POINTER_REGNUM
3572 || regno_first == ARG_POINTER_REGNUM)))
3573 for (i = regno_first; i <= regno_last; ++i)
3574 regs_ever_live[i] = 1;
3576 else
3578 /* Keep track of which basic block each reg appears in. */
3580 int blocknum = pbi->bb->index;
3581 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
3582 REG_BASIC_BLOCK (regno_first) = blocknum;
3583 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
3584 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
3586 /* Count (weighted) number of uses of each reg. */
3587 REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb);
3588 REG_N_REFS (regno_first)++;
3590 for (i = regno_first; i <= regno_last; ++i)
3591 if (! REGNO_REG_SET_P (pbi->reg_live, i))
3593 gcc_assert (!reg_deaths[i]);
3594 reg_deaths[i] = pbi->insn_num;
3598 /* Record and count the insns in which a reg dies. If it is used in
3599 this insn and was dead below the insn then it dies in this insn.
3600 If it was set in this insn, we do not make a REG_DEAD note;
3601 likewise if we already made such a note. */
3602 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
3603 && some_was_dead
3604 && some_not_set)
3606 /* Check for the case where the register dying partially
3607 overlaps the register set by this insn. */
3608 if (regno_first != regno_last)
3609 for (i = regno_first; i <= regno_last; ++i)
3610 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
3612 /* If none of the words in X is needed, make a REG_DEAD note.
3613 Otherwise, we must make partial REG_DEAD notes. */
3614 if (! some_was_live)
3616 if ((pbi->flags & PROP_DEATH_NOTES)
3617 && ! find_regno_note (insn, REG_DEAD, regno_first))
3618 REG_NOTES (insn)
3619 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
3621 if (pbi->flags & PROP_REG_INFO)
3622 REG_N_DEATHS (regno_first)++;
3624 else
3626 /* Don't make a REG_DEAD note for a part of a register
3627 that is set in the insn. */
3628 for (i = regno_first; i <= regno_last; ++i)
3629 if (! REGNO_REG_SET_P (pbi->reg_live, i)
3630 && ! dead_or_set_regno_p (insn, i))
3631 REG_NOTES (insn)
3632 = alloc_EXPR_LIST (REG_DEAD,
3633 regno_reg_rtx[i],
3634 REG_NOTES (insn));
3638 /* Mark the register as being live. */
3639 for (i = regno_first; i <= regno_last; ++i)
3641 #ifdef HAVE_conditional_execution
3642 int this_was_live = REGNO_REG_SET_P (pbi->reg_live, i);
3643 #endif
3645 SET_REGNO_REG_SET (pbi->reg_live, i);
3647 #ifdef HAVE_conditional_execution
3648 /* If this is a conditional use, record that fact. If it is later
3649 conditionally set, we'll know to kill the register. */
3650 if (cond != NULL_RTX)
3652 splay_tree_node node;
3653 struct reg_cond_life_info *rcli;
3654 rtx ncond;
3656 if (this_was_live)
3658 node = splay_tree_lookup (pbi->reg_cond_dead, i);
3659 if (node == NULL)
3661 /* The register was unconditionally live previously.
3662 No need to do anything. */
3664 else
3666 /* The register was conditionally live previously.
3667 Subtract the new life cond from the old death cond. */
3668 rcli = (struct reg_cond_life_info *) node->value;
3669 ncond = rcli->condition;
3670 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
3672 /* If the register is now unconditionally live,
3673 remove the entry in the splay_tree. */
3674 if (ncond == const0_rtx)
3675 splay_tree_remove (pbi->reg_cond_dead, i);
3676 else
3678 rcli->condition = ncond;
3679 SET_REGNO_REG_SET (pbi->reg_cond_reg,
3680 REGNO (XEXP (cond, 0)));
3684 else
3686 /* The register was not previously live at all. Record
3687 the condition under which it is still dead. */
3688 rcli = xmalloc (sizeof (*rcli));
3689 rcli->condition = not_reg_cond (cond);
3690 rcli->stores = const0_rtx;
3691 rcli->orig_condition = const0_rtx;
3692 splay_tree_insert (pbi->reg_cond_dead, i,
3693 (splay_tree_value) rcli);
3695 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
3698 else if (this_was_live)
3700 /* The register may have been conditionally live previously, but
3701 is now unconditionally live. Remove it from the conditionally
3702 dead list, so that a conditional set won't cause us to think
3703 it dead. */
3704 splay_tree_remove (pbi->reg_cond_dead, i);
3706 #endif
3710 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3711 This is done assuming the registers needed from X are those that
3712 have 1-bits in PBI->REG_LIVE.
3714 INSN is the containing instruction. If INSN is dead, this function
3715 is not called. */
3717 static void
3718 mark_used_regs (struct propagate_block_info *pbi, rtx x, rtx cond, rtx insn)
3720 RTX_CODE code;
3721 int regno;
3722 int flags = pbi->flags;
3724 retry:
3725 if (!x)
3726 return;
3727 code = GET_CODE (x);
3728 switch (code)
3730 case LABEL_REF:
3731 case SYMBOL_REF:
3732 case CONST_INT:
3733 case CONST:
3734 case CONST_DOUBLE:
3735 case CONST_VECTOR:
3736 case PC:
3737 case ADDR_VEC:
3738 case ADDR_DIFF_VEC:
3739 return;
3741 #ifdef HAVE_cc0
3742 case CC0:
3743 pbi->cc0_live = 1;
3744 return;
3745 #endif
3747 case CLOBBER:
3748 /* If we are clobbering a MEM, mark any registers inside the address
3749 as being used. */
3750 if (MEM_P (XEXP (x, 0)))
3751 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
3752 return;
3754 case MEM:
3755 /* Don't bother watching stores to mems if this is not the
3756 final pass. We'll not be deleting dead stores this round. */
3757 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
3759 /* Invalidate the data for the last MEM stored, but only if MEM is
3760 something that can be stored into. */
3761 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3762 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3763 /* Needn't clear the memory set list. */
3765 else
3767 rtx temp = pbi->mem_set_list;
3768 rtx prev = NULL_RTX;
3769 rtx next;
3771 while (temp)
3773 next = XEXP (temp, 1);
3774 if (anti_dependence (XEXP (temp, 0), x))
3776 /* Splice temp out of the list. */
3777 if (prev)
3778 XEXP (prev, 1) = next;
3779 else
3780 pbi->mem_set_list = next;
3781 free_EXPR_LIST_node (temp);
3782 pbi->mem_set_list_len--;
3784 else
3785 prev = temp;
3786 temp = next;
3790 /* If the memory reference had embedded side effects (autoincrement
3791 address modes. Then we may need to kill some entries on the
3792 memory set list. */
3793 if (insn)
3794 for_each_rtx (&PATTERN (insn), invalidate_mems_from_autoinc, pbi);
3797 #ifdef AUTO_INC_DEC
3798 if (flags & PROP_AUTOINC)
3799 find_auto_inc (pbi, x, insn);
3800 #endif
3801 break;
3803 case SUBREG:
3804 #ifdef CANNOT_CHANGE_MODE_CLASS
3805 if (flags & PROP_REG_INFO)
3806 record_subregs_of_mode (x);
3807 #endif
3809 /* While we're here, optimize this case. */
3810 x = SUBREG_REG (x);
3811 if (!REG_P (x))
3812 goto retry;
3813 /* Fall through. */
3815 case REG:
3816 /* See a register other than being set => mark it as needed. */
3817 mark_used_reg (pbi, x, cond, insn);
3818 return;
3820 case SET:
3822 rtx testreg = SET_DEST (x);
3823 int mark_dest = 0;
3825 /* If storing into MEM, don't show it as being used. But do
3826 show the address as being used. */
3827 if (MEM_P (testreg))
3829 #ifdef AUTO_INC_DEC
3830 if (flags & PROP_AUTOINC)
3831 find_auto_inc (pbi, testreg, insn);
3832 #endif
3833 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
3834 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3835 return;
3838 /* Storing in STRICT_LOW_PART is like storing in a reg
3839 in that this SET might be dead, so ignore it in TESTREG.
3840 but in some other ways it is like using the reg.
3842 Storing in a SUBREG or a bit field is like storing the entire
3843 register in that if the register's value is not used
3844 then this SET is not needed. */
3845 while (GET_CODE (testreg) == STRICT_LOW_PART
3846 || GET_CODE (testreg) == ZERO_EXTRACT
3847 || GET_CODE (testreg) == SIGN_EXTRACT
3848 || GET_CODE (testreg) == SUBREG)
3850 #ifdef CANNOT_CHANGE_MODE_CLASS
3851 if ((flags & PROP_REG_INFO) && GET_CODE (testreg) == SUBREG)
3852 record_subregs_of_mode (testreg);
3853 #endif
3855 /* Modifying a single register in an alternate mode
3856 does not use any of the old value. But these other
3857 ways of storing in a register do use the old value. */
3858 if (GET_CODE (testreg) == SUBREG
3859 && !((REG_BYTES (SUBREG_REG (testreg))
3860 + UNITS_PER_WORD - 1) / UNITS_PER_WORD
3861 > (REG_BYTES (testreg)
3862 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
3864 else
3865 mark_dest = 1;
3867 testreg = XEXP (testreg, 0);
3870 /* If this is a store into a register or group of registers,
3871 recursively scan the value being stored. */
3873 if ((GET_CODE (testreg) == PARALLEL
3874 && GET_MODE (testreg) == BLKmode)
3875 || (REG_P (testreg)
3876 && (regno = REGNO (testreg),
3877 ! (regno == FRAME_POINTER_REGNUM
3878 && (! reload_completed || frame_pointer_needed)))
3879 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3880 && ! (regno == HARD_FRAME_POINTER_REGNUM
3881 && (! reload_completed || frame_pointer_needed))
3882 #endif
3883 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3884 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
3885 #endif
3888 if (mark_dest)
3889 mark_used_regs (pbi, SET_DEST (x), cond, insn);
3890 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3891 return;
3894 break;
3896 case ASM_OPERANDS:
3897 case UNSPEC_VOLATILE:
3898 case TRAP_IF:
3899 case ASM_INPUT:
3901 /* Traditional and volatile asm instructions must be considered to use
3902 and clobber all hard registers, all pseudo-registers and all of
3903 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3905 Consider for instance a volatile asm that changes the fpu rounding
3906 mode. An insn should not be moved across this even if it only uses
3907 pseudo-regs because it might give an incorrectly rounded result.
3909 ?!? Unfortunately, marking all hard registers as live causes massive
3910 problems for the register allocator and marking all pseudos as live
3911 creates mountains of uninitialized variable warnings.
3913 So for now, just clear the memory set list and mark any regs
3914 we can find in ASM_OPERANDS as used. */
3915 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
3917 free_EXPR_LIST_list (&pbi->mem_set_list);
3918 pbi->mem_set_list_len = 0;
3921 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3922 We can not just fall through here since then we would be confused
3923 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3924 traditional asms unlike their normal usage. */
3925 if (code == ASM_OPERANDS)
3927 int j;
3929 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
3930 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
3932 break;
3935 case COND_EXEC:
3936 gcc_assert (!cond);
3938 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
3940 cond = COND_EXEC_TEST (x);
3941 x = COND_EXEC_CODE (x);
3942 goto retry;
3944 default:
3945 break;
3948 /* Recursively scan the operands of this expression. */
3951 const char * const fmt = GET_RTX_FORMAT (code);
3952 int i;
3954 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3956 if (fmt[i] == 'e')
3958 /* Tail recursive case: save a function call level. */
3959 if (i == 0)
3961 x = XEXP (x, 0);
3962 goto retry;
3964 mark_used_regs (pbi, XEXP (x, i), cond, insn);
3966 else if (fmt[i] == 'E')
3968 int j;
3969 for (j = 0; j < XVECLEN (x, i); j++)
3970 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
3976 #ifdef AUTO_INC_DEC
3978 static int
3979 try_pre_increment_1 (struct propagate_block_info *pbi, rtx insn)
3981 /* Find the next use of this reg. If in same basic block,
3982 make it do pre-increment or pre-decrement if appropriate. */
3983 rtx x = single_set (insn);
3984 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
3985 * INTVAL (XEXP (SET_SRC (x), 1)));
3986 int regno = REGNO (SET_DEST (x));
3987 rtx y = pbi->reg_next_use[regno];
3988 if (y != 0
3989 && SET_DEST (x) != stack_pointer_rtx
3990 && BLOCK_NUM (y) == BLOCK_NUM (insn)
3991 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3992 mode would be better. */
3993 && ! dead_or_set_p (y, SET_DEST (x))
3994 && try_pre_increment (y, SET_DEST (x), amount))
3996 /* We have found a suitable auto-increment and already changed
3997 insn Y to do it. So flush this increment instruction. */
3998 propagate_block_delete_insn (insn);
4000 /* Count a reference to this reg for the increment insn we are
4001 deleting. When a reg is incremented, spilling it is worse,
4002 so we want to make that less likely. */
4003 if (regno >= FIRST_PSEUDO_REGISTER)
4005 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
4006 REG_N_SETS (regno)++;
4009 /* Flush any remembered memories depending on the value of
4010 the incremented register. */
4011 invalidate_mems_from_set (pbi, SET_DEST (x));
4013 return 1;
4015 return 0;
4018 /* Try to change INSN so that it does pre-increment or pre-decrement
4019 addressing on register REG in order to add AMOUNT to REG.
4020 AMOUNT is negative for pre-decrement.
4021 Returns 1 if the change could be made.
4022 This checks all about the validity of the result of modifying INSN. */
4024 static int
4025 try_pre_increment (rtx insn, rtx reg, HOST_WIDE_INT amount)
4027 rtx use;
4029 /* Nonzero if we can try to make a pre-increment or pre-decrement.
4030 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
4031 int pre_ok = 0;
4032 /* Nonzero if we can try to make a post-increment or post-decrement.
4033 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
4034 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
4035 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
4036 int post_ok = 0;
4038 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
4039 int do_post = 0;
4041 /* From the sign of increment, see which possibilities are conceivable
4042 on this target machine. */
4043 if (HAVE_PRE_INCREMENT && amount > 0)
4044 pre_ok = 1;
4045 if (HAVE_POST_INCREMENT && amount > 0)
4046 post_ok = 1;
4048 if (HAVE_PRE_DECREMENT && amount < 0)
4049 pre_ok = 1;
4050 if (HAVE_POST_DECREMENT && amount < 0)
4051 post_ok = 1;
4053 if (! (pre_ok || post_ok))
4054 return 0;
4056 /* It is not safe to add a side effect to a jump insn
4057 because if the incremented register is spilled and must be reloaded
4058 there would be no way to store the incremented value back in memory. */
4060 if (JUMP_P (insn))
4061 return 0;
4063 use = 0;
4064 if (pre_ok)
4065 use = find_use_as_address (PATTERN (insn), reg, 0);
4066 if (post_ok && (use == 0 || use == (rtx) (size_t) 1))
4068 use = find_use_as_address (PATTERN (insn), reg, -amount);
4069 do_post = 1;
4072 if (use == 0 || use == (rtx) (size_t) 1)
4073 return 0;
4075 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
4076 return 0;
4078 /* See if this combination of instruction and addressing mode exists. */
4079 if (! validate_change (insn, &XEXP (use, 0),
4080 gen_rtx_fmt_e (amount > 0
4081 ? (do_post ? POST_INC : PRE_INC)
4082 : (do_post ? POST_DEC : PRE_DEC),
4083 Pmode, reg), 0))
4084 return 0;
4086 /* Record that this insn now has an implicit side effect on X. */
4087 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
4088 return 1;
4091 #endif /* AUTO_INC_DEC */
4093 /* Find the place in the rtx X where REG is used as a memory address.
4094 Return the MEM rtx that so uses it.
4095 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4096 (plus REG (const_int PLUSCONST)).
4098 If such an address does not appear, return 0.
4099 If REG appears more than once, or is used other than in such an address,
4100 return (rtx) 1. */
4103 find_use_as_address (rtx x, rtx reg, HOST_WIDE_INT plusconst)
4105 enum rtx_code code = GET_CODE (x);
4106 const char * const fmt = GET_RTX_FORMAT (code);
4107 int i;
4108 rtx value = 0;
4109 rtx tem;
4111 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
4112 return x;
4114 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
4115 && XEXP (XEXP (x, 0), 0) == reg
4116 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
4117 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
4118 return x;
4120 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
4122 /* If REG occurs inside a MEM used in a bit-field reference,
4123 that is unacceptable. */
4124 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
4125 return (rtx) (size_t) 1;
4128 if (x == reg)
4129 return (rtx) (size_t) 1;
4131 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4133 if (fmt[i] == 'e')
4135 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
4136 if (value == 0)
4137 value = tem;
4138 else if (tem != 0)
4139 return (rtx) (size_t) 1;
4141 else if (fmt[i] == 'E')
4143 int j;
4144 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4146 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
4147 if (value == 0)
4148 value = tem;
4149 else if (tem != 0)
4150 return (rtx) (size_t) 1;
4155 return value;
4158 /* Write information about registers and basic blocks into FILE.
4159 This is part of making a debugging dump. */
4161 void
4162 dump_regset (regset r, FILE *outf)
4164 unsigned i;
4165 reg_set_iterator rsi;
4167 if (r == NULL)
4169 fputs (" (nil)", outf);
4170 return;
4173 EXECUTE_IF_SET_IN_REG_SET (r, 0, i, rsi)
4175 fprintf (outf, " %d", i);
4176 if (i < FIRST_PSEUDO_REGISTER)
4177 fprintf (outf, " [%s]",
4178 reg_names[i]);
4182 /* Print a human-readable representation of R on the standard error
4183 stream. This function is designed to be used from within the
4184 debugger. */
4186 void
4187 debug_regset (regset r)
4189 dump_regset (r, stderr);
4190 putc ('\n', stderr);
4193 /* Recompute register set/reference counts immediately prior to register
4194 allocation.
4196 This avoids problems with set/reference counts changing to/from values
4197 which have special meanings to the register allocators.
4199 Additionally, the reference counts are the primary component used by the
4200 register allocators to prioritize pseudos for allocation to hard regs.
4201 More accurate reference counts generally lead to better register allocation.
4203 F is the first insn to be scanned.
4205 LOOP_STEP denotes how much loop_depth should be incremented per
4206 loop nesting level in order to increase the ref count more for
4207 references in a loop.
4209 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4210 possibly other information which is used by the register allocators. */
4212 void
4213 recompute_reg_usage (rtx f ATTRIBUTE_UNUSED, int loop_step ATTRIBUTE_UNUSED)
4215 allocate_reg_life_data ();
4216 /* distribute_notes in combiner fails to convert some of the REG_UNUSED notes
4217 to REG_DEAD notes. This causes CHECK_DEAD_NOTES in sched1 to abort. To
4218 solve this update the DEATH_NOTES here. */
4219 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO | PROP_DEATH_NOTES);
4222 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4223 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4224 of the number of registers that died. */
4227 count_or_remove_death_notes (sbitmap blocks, int kill)
4229 int count = 0;
4230 int i;
4231 basic_block bb;
4233 /* This used to be a loop over all the blocks with a membership test
4234 inside the loop. That can be amazingly expensive on a large CFG
4235 when only a small number of bits are set in BLOCKs (for example,
4236 the calls from the scheduler typically have very few bits set).
4238 For extra credit, someone should convert BLOCKS to a bitmap rather
4239 than an sbitmap. */
4240 if (blocks)
4242 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4244 count += count_or_remove_death_notes_bb (BASIC_BLOCK (i), kill);
4247 else
4249 FOR_EACH_BB (bb)
4251 count += count_or_remove_death_notes_bb (bb, kill);
4255 return count;
4258 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from basic
4259 block BB. Returns a count of the number of registers that died. */
4261 static int
4262 count_or_remove_death_notes_bb (basic_block bb, int kill)
4264 int count = 0;
4265 rtx insn;
4267 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
4269 if (INSN_P (insn))
4271 rtx *pprev = &REG_NOTES (insn);
4272 rtx link = *pprev;
4274 while (link)
4276 switch (REG_NOTE_KIND (link))
4278 case REG_DEAD:
4279 if (REG_P (XEXP (link, 0)))
4281 rtx reg = XEXP (link, 0);
4282 int n;
4284 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
4285 n = 1;
4286 else
4287 n = hard_regno_nregs[REGNO (reg)][GET_MODE (reg)];
4288 count += n;
4291 /* Fall through. */
4293 case REG_UNUSED:
4294 if (kill)
4296 rtx next = XEXP (link, 1);
4297 free_EXPR_LIST_node (link);
4298 *pprev = link = next;
4299 break;
4301 /* Fall through. */
4303 default:
4304 pprev = &XEXP (link, 1);
4305 link = *pprev;
4306 break;
4311 if (insn == BB_END (bb))
4312 break;
4315 return count;
4318 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4319 if blocks is NULL. */
4321 static void
4322 clear_log_links (sbitmap blocks)
4324 rtx insn;
4325 int i;
4327 if (!blocks)
4329 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4330 if (INSN_P (insn))
4331 free_INSN_LIST_list (&LOG_LINKS (insn));
4333 else
4334 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4336 basic_block bb = BASIC_BLOCK (i);
4338 for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
4339 insn = NEXT_INSN (insn))
4340 if (INSN_P (insn))
4341 free_INSN_LIST_list (&LOG_LINKS (insn));
4345 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4346 correspond to the hard registers, if any, set in that map. This
4347 could be done far more efficiently by having all sorts of special-cases
4348 with moving single words, but probably isn't worth the trouble. */
4350 void
4351 reg_set_to_hard_reg_set (HARD_REG_SET *to, bitmap from)
4353 unsigned i;
4354 bitmap_iterator bi;
4356 EXECUTE_IF_SET_IN_BITMAP (from, 0, i, bi)
4358 if (i >= FIRST_PSEUDO_REGISTER)
4359 return;
4360 SET_HARD_REG_BIT (*to, i);