* arm.md (IOR (COMPARISON) (AND)): New define_splits.
[official-gcc.git] / gcc / flow.c
blob952e7d9eb9252e4470f5836ab992086f3adaa53d
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 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 (bb->local_live, bb->local_set)
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 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
145 the stack pointer does not matter. The value is tested only in
146 functions that have frame pointers.
147 No definition is equivalent to always zero. */
148 #ifndef EXIT_IGNORE_STACK
149 #define EXIT_IGNORE_STACK 0
150 #endif
152 #ifndef HAVE_epilogue
153 #define HAVE_epilogue 0
154 #endif
155 #ifndef HAVE_prologue
156 #define HAVE_prologue 0
157 #endif
158 #ifndef HAVE_sibcall_epilogue
159 #define HAVE_sibcall_epilogue 0
160 #endif
162 #ifndef LOCAL_REGNO
163 #define LOCAL_REGNO(REGNO) 0
164 #endif
165 #ifndef EPILOGUE_USES
166 #define EPILOGUE_USES(REGNO) 0
167 #endif
168 #ifndef EH_USES
169 #define EH_USES(REGNO) 0
170 #endif
172 #ifdef HAVE_conditional_execution
173 #ifndef REVERSE_CONDEXEC_PREDICATES_P
174 #define REVERSE_CONDEXEC_PREDICATES_P(x, y) ((x) == reverse_condition (y))
175 #endif
176 #endif
178 /* Nonzero if the second flow pass has completed. */
179 int flow2_completed;
181 /* Maximum register number used in this function, plus one. */
183 int max_regno;
185 /* Indexed by n, giving various register information */
187 varray_type reg_n_info;
189 /* Size of a regset for the current function,
190 in (1) bytes and (2) elements. */
192 int regset_bytes;
193 int regset_size;
195 /* Regset of regs live when calls to `setjmp'-like functions happen. */
196 /* ??? Does this exist only for the setjmp-clobbered warning message? */
198 regset regs_live_at_setjmp;
200 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
201 that have to go in the same hard reg.
202 The first two regs in the list are a pair, and the next two
203 are another pair, etc. */
204 rtx regs_may_share;
206 /* Callback that determines if it's ok for a function to have no
207 noreturn attribute. */
208 int (*lang_missing_noreturn_ok_p) (tree);
210 /* Set of registers that may be eliminable. These are handled specially
211 in updating regs_ever_live. */
213 static HARD_REG_SET elim_reg_set;
215 /* Holds information for tracking conditional register life information. */
216 struct reg_cond_life_info
218 /* A boolean expression of conditions under which a register is dead. */
219 rtx condition;
220 /* Conditions under which a register is dead at the basic block end. */
221 rtx orig_condition;
223 /* A boolean expression of conditions under which a register has been
224 stored into. */
225 rtx stores;
227 /* ??? Could store mask of bytes that are dead, so that we could finally
228 track lifetimes of multi-word registers accessed via subregs. */
231 /* For use in communicating between propagate_block and its subroutines.
232 Holds all information needed to compute life and def-use information. */
234 struct propagate_block_info
236 /* The basic block we're considering. */
237 basic_block bb;
239 /* Bit N is set if register N is conditionally or unconditionally live. */
240 regset reg_live;
242 /* Bit N is set if register N is set this insn. */
243 regset new_set;
245 /* Element N is the next insn that uses (hard or pseudo) register N
246 within the current basic block; or zero, if there is no such insn. */
247 rtx *reg_next_use;
249 /* Contains a list of all the MEMs we are tracking for dead store
250 elimination. */
251 rtx mem_set_list;
253 /* If non-null, record the set of registers set unconditionally in the
254 basic block. */
255 regset local_set;
257 /* If non-null, record the set of registers set conditionally in the
258 basic block. */
259 regset cond_local_set;
261 #ifdef HAVE_conditional_execution
262 /* Indexed by register number, holds a reg_cond_life_info for each
263 register that is not unconditionally live or dead. */
264 splay_tree reg_cond_dead;
266 /* Bit N is set if register N is in an expression in reg_cond_dead. */
267 regset reg_cond_reg;
268 #endif
270 /* The length of mem_set_list. */
271 int mem_set_list_len;
273 /* Nonzero if the value of CC0 is live. */
274 int cc0_live;
276 /* Flags controlling the set of information propagate_block collects. */
277 int flags;
280 /* Number of dead insns removed. */
281 static int ndead;
283 /* Maximum length of pbi->mem_set_list before we start dropping
284 new elements on the floor. */
285 #define MAX_MEM_SET_LIST_LEN 100
287 /* Forward declarations */
288 static int verify_wide_reg_1 (rtx *, void *);
289 static void verify_wide_reg (int, basic_block);
290 static void verify_local_live_at_start (regset, basic_block);
291 static void notice_stack_pointer_modification_1 (rtx, rtx, void *);
292 static void notice_stack_pointer_modification (rtx);
293 static void mark_reg (rtx, void *);
294 static void mark_regs_live_at_end (regset);
295 static void calculate_global_regs_live (sbitmap, sbitmap, int);
296 static void propagate_block_delete_insn (rtx);
297 static rtx propagate_block_delete_libcall (rtx, rtx);
298 static int insn_dead_p (struct propagate_block_info *, rtx, int, rtx);
299 static int libcall_dead_p (struct propagate_block_info *, rtx, rtx);
300 static void mark_set_regs (struct propagate_block_info *, rtx, rtx);
301 static void mark_set_1 (struct propagate_block_info *, enum rtx_code, rtx,
302 rtx, rtx, int);
303 static int find_regno_partial (rtx *, void *);
305 #ifdef HAVE_conditional_execution
306 static int mark_regno_cond_dead (struct propagate_block_info *, int, rtx);
307 static void free_reg_cond_life_info (splay_tree_value);
308 static int flush_reg_cond_reg_1 (splay_tree_node, void *);
309 static void flush_reg_cond_reg (struct propagate_block_info *, int);
310 static rtx elim_reg_cond (rtx, unsigned int);
311 static rtx ior_reg_cond (rtx, rtx, int);
312 static rtx not_reg_cond (rtx);
313 static rtx and_reg_cond (rtx, rtx, int);
314 #endif
315 #ifdef AUTO_INC_DEC
316 static void attempt_auto_inc (struct propagate_block_info *, rtx, rtx, rtx,
317 rtx, rtx);
318 static void find_auto_inc (struct propagate_block_info *, rtx, rtx);
319 static int try_pre_increment_1 (struct propagate_block_info *, rtx);
320 static int try_pre_increment (rtx, rtx, HOST_WIDE_INT);
321 #endif
322 static void mark_used_reg (struct propagate_block_info *, rtx, rtx, rtx);
323 static void mark_used_regs (struct propagate_block_info *, rtx, rtx, rtx);
324 void debug_flow_info (void);
325 static void add_to_mem_set_list (struct propagate_block_info *, rtx);
326 static int invalidate_mems_from_autoinc (rtx *, void *);
327 static void invalidate_mems_from_set (struct propagate_block_info *, rtx);
328 static void clear_log_links (sbitmap);
329 static int count_or_remove_death_notes_bb (basic_block, int);
332 void
333 check_function_return_warnings (void)
335 if (warn_missing_noreturn
336 && !TREE_THIS_VOLATILE (cfun->decl)
337 && EXIT_BLOCK_PTR->pred == NULL
338 && (lang_missing_noreturn_ok_p
339 && !lang_missing_noreturn_ok_p (cfun->decl)))
340 warning ("function might be possible candidate for attribute `noreturn'");
342 /* If we have a path to EXIT, then we do return. */
343 if (TREE_THIS_VOLATILE (cfun->decl)
344 && EXIT_BLOCK_PTR->pred != NULL)
345 warning ("`noreturn' function does return");
347 /* If the clobber_return_insn appears in some basic block, then we
348 do reach the end without returning a value. */
349 else if (warn_return_type
350 && cfun->x_clobber_return_insn != NULL
351 && EXIT_BLOCK_PTR->pred != NULL)
353 int max_uid = get_max_uid ();
355 /* If clobber_return_insn was excised by jump1, then renumber_insns
356 can make max_uid smaller than the number still recorded in our rtx.
357 That's fine, since this is a quick way of verifying that the insn
358 is no longer in the chain. */
359 if (INSN_UID (cfun->x_clobber_return_insn) < max_uid)
361 rtx insn;
363 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
364 if (insn == cfun->x_clobber_return_insn)
366 warning ("control reaches end of non-void function");
367 break;
373 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
374 note associated with the BLOCK. */
377 first_insn_after_basic_block_note (basic_block block)
379 rtx insn;
381 /* Get the first instruction in the block. */
382 insn = block->head;
384 if (insn == NULL_RTX)
385 return NULL_RTX;
386 if (GET_CODE (insn) == CODE_LABEL)
387 insn = NEXT_INSN (insn);
388 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
389 abort ();
391 return NEXT_INSN (insn);
394 /* Perform data flow analysis.
395 F is the first insn of the function; FLAGS is a set of PROP_* flags
396 to be used in accumulating flow info. */
398 void
399 life_analysis (rtx f, FILE *file, int flags)
401 #ifdef ELIMINABLE_REGS
402 int i;
403 static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS;
404 #endif
406 /* Record which registers will be eliminated. We use this in
407 mark_used_regs. */
409 CLEAR_HARD_REG_SET (elim_reg_set);
411 #ifdef ELIMINABLE_REGS
412 for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
413 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
414 #else
415 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
416 #endif
419 #ifdef CANNOT_CHANGE_MODE_CLASS
420 if (flags & PROP_REG_INFO)
421 bitmap_initialize (&subregs_of_mode, 1);
422 #endif
424 if (! optimize)
425 flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES);
427 /* The post-reload life analysis have (on a global basis) the same
428 registers live as was computed by reload itself. elimination
429 Otherwise offsets and such may be incorrect.
431 Reload will make some registers as live even though they do not
432 appear in the rtl.
434 We don't want to create new auto-incs after reload, since they
435 are unlikely to be useful and can cause problems with shared
436 stack slots. */
437 if (reload_completed)
438 flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
440 /* We want alias analysis information for local dead store elimination. */
441 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
442 init_alias_analysis ();
444 /* Always remove no-op moves. Do this before other processing so
445 that we don't have to keep re-scanning them. */
446 delete_noop_moves (f);
448 /* Some targets can emit simpler epilogues if they know that sp was
449 not ever modified during the function. After reload, of course,
450 we've already emitted the epilogue so there's no sense searching. */
451 if (! reload_completed)
452 notice_stack_pointer_modification (f);
454 /* Allocate and zero out data structures that will record the
455 data from lifetime analysis. */
456 allocate_reg_life_data ();
457 allocate_bb_life_data ();
459 /* Find the set of registers live on function exit. */
460 mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
462 /* "Update" life info from zero. It'd be nice to begin the
463 relaxation with just the exit and noreturn blocks, but that set
464 is not immediately handy. */
466 if (flags & PROP_REG_INFO)
468 memset (regs_ever_live, 0, sizeof (regs_ever_live));
469 memset (regs_asm_clobbered, 0, sizeof (regs_asm_clobbered));
471 update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
473 /* Clean up. */
474 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
475 end_alias_analysis ();
477 if (file)
478 dump_flow_info (file);
480 free_basic_block_vars (1);
482 /* Removing dead insns should've made jumptables really dead. */
483 delete_dead_jumptables ();
486 /* A subroutine of verify_wide_reg, called through for_each_rtx.
487 Search for REGNO. If found, return 2 if it is not wider than
488 word_mode. */
490 static int
491 verify_wide_reg_1 (rtx *px, void *pregno)
493 rtx x = *px;
494 unsigned int regno = *(int *) pregno;
496 if (GET_CODE (x) == REG && REGNO (x) == regno)
498 if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
499 return 2;
500 return 1;
502 return 0;
505 /* A subroutine of verify_local_live_at_start. Search through insns
506 of BB looking for register REGNO. */
508 static void
509 verify_wide_reg (int regno, basic_block bb)
511 rtx head = bb->head, end = bb->end;
513 while (1)
515 if (INSN_P (head))
517 int r = for_each_rtx (&PATTERN (head), verify_wide_reg_1, &regno);
518 if (r == 1)
519 return;
520 if (r == 2)
521 break;
523 if (head == end)
524 break;
525 head = NEXT_INSN (head);
528 if (rtl_dump_file)
530 fprintf (rtl_dump_file, "Register %d died unexpectedly.\n", regno);
531 dump_bb (bb, rtl_dump_file);
533 abort ();
536 /* A subroutine of update_life_info. Verify that there are no untoward
537 changes in live_at_start during a local update. */
539 static void
540 verify_local_live_at_start (regset new_live_at_start, basic_block bb)
542 if (reload_completed)
544 /* After reload, there are no pseudos, nor subregs of multi-word
545 registers. The regsets should exactly match. */
546 if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
548 if (rtl_dump_file)
550 fprintf (rtl_dump_file,
551 "live_at_start mismatch in bb %d, aborting\nNew:\n",
552 bb->index);
553 debug_bitmap_file (rtl_dump_file, new_live_at_start);
554 fputs ("Old:\n", rtl_dump_file);
555 dump_bb (bb, rtl_dump_file);
557 abort ();
560 else
562 int i;
564 /* Find the set of changed registers. */
565 XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
567 EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i,
569 /* No registers should die. */
570 if (REGNO_REG_SET_P (bb->global_live_at_start, i))
572 if (rtl_dump_file)
574 fprintf (rtl_dump_file,
575 "Register %d died unexpectedly.\n", i);
576 dump_bb (bb, rtl_dump_file);
578 abort ();
581 /* Verify that the now-live register is wider than word_mode. */
582 verify_wide_reg (i, bb);
587 /* Updates life information starting with the basic blocks set in BLOCKS.
588 If BLOCKS is null, consider it to be the universal set.
590 If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholing,
591 we are only expecting local modifications to basic blocks. If we find
592 extra registers live at the beginning of a block, then we either killed
593 useful data, or we have a broken split that wants data not provided.
594 If we find registers removed from live_at_start, that means we have
595 a broken peephole that is killing a register it shouldn't.
597 ??? This is not true in one situation -- when a pre-reload splitter
598 generates subregs of a multi-word pseudo, current life analysis will
599 lose the kill. So we _can_ have a pseudo go live. How irritating.
601 It is also not true when a peephole decides that it doesn't need one
602 or more of the inputs.
604 Including PROP_REG_INFO does not properly refresh regs_ever_live
605 unless the caller resets it to zero. */
608 update_life_info (sbitmap blocks, enum update_life_extent extent, int prop_flags)
610 regset tmp;
611 regset_head tmp_head;
612 int i;
613 int stabilized_prop_flags = prop_flags;
614 basic_block bb;
616 tmp = INITIALIZE_REG_SET (tmp_head);
617 ndead = 0;
619 timevar_push ((extent == UPDATE_LIFE_LOCAL || blocks)
620 ? TV_LIFE_UPDATE : TV_LIFE);
622 /* Changes to the CFG are only allowed when
623 doing a global update for the entire CFG. */
624 if ((prop_flags & PROP_ALLOW_CFG_CHANGES)
625 && (extent == UPDATE_LIFE_LOCAL || blocks))
626 abort ();
628 /* For a global update, we go through the relaxation process again. */
629 if (extent != UPDATE_LIFE_LOCAL)
631 for ( ; ; )
633 int changed = 0;
635 calculate_global_regs_live (blocks, blocks,
636 prop_flags & (PROP_SCAN_DEAD_CODE
637 | PROP_SCAN_DEAD_STORES
638 | PROP_ALLOW_CFG_CHANGES));
640 if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
641 != (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
642 break;
644 /* Removing dead code may allow the CFG to be simplified which
645 in turn may allow for further dead code detection / removal. */
646 FOR_EACH_BB_REVERSE (bb)
648 COPY_REG_SET (tmp, bb->global_live_at_end);
649 changed |= propagate_block (bb, tmp, NULL, NULL,
650 prop_flags & (PROP_SCAN_DEAD_CODE
651 | PROP_SCAN_DEAD_STORES
652 | PROP_KILL_DEAD_CODE));
655 /* Don't pass PROP_SCAN_DEAD_CODE or PROP_KILL_DEAD_CODE to
656 subsequent propagate_block calls, since removing or acting as
657 removing dead code can affect global register liveness, which
658 is supposed to be finalized for this call after this loop. */
659 stabilized_prop_flags
660 &= ~(PROP_SCAN_DEAD_CODE | PROP_SCAN_DEAD_STORES
661 | PROP_KILL_DEAD_CODE);
663 if (! changed)
664 break;
666 /* We repeat regardless of what cleanup_cfg says. If there were
667 instructions deleted above, that might have been only a
668 partial improvement (see MAX_MEM_SET_LIST_LEN usage).
669 Further improvement may be possible. */
670 cleanup_cfg (CLEANUP_EXPENSIVE);
672 /* Zap the life information from the last round. If we don't
673 do this, we can wind up with registers that no longer appear
674 in the code being marked live at entry, which twiggs bogus
675 warnings from regno_uninitialized. */
676 FOR_EACH_BB (bb)
678 CLEAR_REG_SET (bb->global_live_at_start);
679 CLEAR_REG_SET (bb->global_live_at_end);
683 /* If asked, remove notes from the blocks we'll update. */
684 if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
685 count_or_remove_death_notes (blocks, 1);
688 /* Clear log links in case we are asked to (re)compute them. */
689 if (prop_flags & PROP_LOG_LINKS)
690 clear_log_links (blocks);
692 if (blocks)
694 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
696 bb = BASIC_BLOCK (i);
698 COPY_REG_SET (tmp, bb->global_live_at_end);
699 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags);
701 if (extent == UPDATE_LIFE_LOCAL)
702 verify_local_live_at_start (tmp, bb);
705 else
707 FOR_EACH_BB_REVERSE (bb)
709 COPY_REG_SET (tmp, bb->global_live_at_end);
711 propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags);
713 if (extent == UPDATE_LIFE_LOCAL)
714 verify_local_live_at_start (tmp, bb);
718 FREE_REG_SET (tmp);
720 if (prop_flags & PROP_REG_INFO)
722 /* The only pseudos that are live at the beginning of the function
723 are those that were not set anywhere in the function. local-alloc
724 doesn't know how to handle these correctly, so mark them as not
725 local to any one basic block. */
726 EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
727 FIRST_PSEUDO_REGISTER, i,
728 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
730 /* We have a problem with any pseudoreg that lives across the setjmp.
731 ANSI says that if a user variable does not change in value between
732 the setjmp and the longjmp, then the longjmp preserves it. This
733 includes longjmp from a place where the pseudo appears dead.
734 (In principle, the value still exists if it is in scope.)
735 If the pseudo goes in a hard reg, some other value may occupy
736 that hard reg where this pseudo is dead, thus clobbering the pseudo.
737 Conclusion: such a pseudo must not go in a hard reg. */
738 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
739 FIRST_PSEUDO_REGISTER, i,
741 if (regno_reg_rtx[i] != 0)
743 REG_LIVE_LENGTH (i) = -1;
744 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
748 timevar_pop ((extent == UPDATE_LIFE_LOCAL || blocks)
749 ? TV_LIFE_UPDATE : TV_LIFE);
750 if (ndead && rtl_dump_file)
751 fprintf (rtl_dump_file, "deleted %i dead insns\n", ndead);
752 return ndead;
755 /* Update life information in all blocks where BB_DIRTY is set. */
758 update_life_info_in_dirty_blocks (enum update_life_extent extent, int prop_flags)
760 sbitmap update_life_blocks = sbitmap_alloc (last_basic_block);
761 int n = 0;
762 basic_block bb;
763 int retval = 0;
765 sbitmap_zero (update_life_blocks);
766 FOR_EACH_BB (bb)
768 if (extent == UPDATE_LIFE_LOCAL)
770 if (bb->flags & BB_DIRTY)
772 SET_BIT (update_life_blocks, bb->index);
773 n++;
776 else
778 /* ??? Bootstrap with -march=pentium4 fails to terminate
779 with only a partial life update. */
780 SET_BIT (update_life_blocks, bb->index);
781 if (bb->flags & BB_DIRTY)
782 n++;
786 if (n)
787 retval = update_life_info (update_life_blocks, extent, prop_flags);
789 sbitmap_free (update_life_blocks);
790 return retval;
793 /* Free the variables allocated by find_basic_blocks.
795 KEEP_HEAD_END_P is nonzero if basic_block_info is not to be freed. */
797 void
798 free_basic_block_vars (int keep_head_end_p)
800 if (! keep_head_end_p)
802 if (basic_block_info)
804 clear_edges ();
805 VARRAY_FREE (basic_block_info);
807 n_basic_blocks = 0;
808 last_basic_block = 0;
810 ENTRY_BLOCK_PTR->aux = NULL;
811 ENTRY_BLOCK_PTR->global_live_at_end = NULL;
812 EXIT_BLOCK_PTR->aux = NULL;
813 EXIT_BLOCK_PTR->global_live_at_start = NULL;
817 /* Delete any insns that copy a register to itself. */
820 delete_noop_moves (rtx f ATTRIBUTE_UNUSED)
822 rtx insn, next;
823 basic_block bb;
824 int nnoops = 0;
826 FOR_EACH_BB (bb)
828 for (insn = bb->head; insn != NEXT_INSN (bb->end); insn = next)
830 next = NEXT_INSN (insn);
831 if (INSN_P (insn) && noop_move_p (insn))
833 rtx note;
835 /* If we're about to remove the first insn of a libcall
836 then move the libcall note to the next real insn and
837 update the retval note. */
838 if ((note = find_reg_note (insn, REG_LIBCALL, NULL_RTX))
839 && XEXP (note, 0) != insn)
841 rtx new_libcall_insn = next_real_insn (insn);
842 rtx retval_note = find_reg_note (XEXP (note, 0),
843 REG_RETVAL, NULL_RTX);
844 REG_NOTES (new_libcall_insn)
845 = gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0),
846 REG_NOTES (new_libcall_insn));
847 XEXP (retval_note, 0) = new_libcall_insn;
850 delete_insn_and_edges (insn);
851 nnoops++;
855 if (nnoops && rtl_dump_file)
856 fprintf (rtl_dump_file, "deleted %i noop moves", nnoops);
857 return nnoops;
860 /* Delete any jump tables never referenced. We can't delete them at the
861 time of removing tablejump insn as they are referenced by the preceding
862 insns computing the destination, so we delay deleting and garbagecollect
863 them once life information is computed. */
864 void
865 delete_dead_jumptables (void)
867 rtx insn, next;
868 for (insn = get_insns (); insn; insn = next)
870 next = NEXT_INSN (insn);
871 if (GET_CODE (insn) == CODE_LABEL
872 && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
873 && GET_CODE (next) == JUMP_INSN
874 && (GET_CODE (PATTERN (next)) == ADDR_VEC
875 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
877 if (rtl_dump_file)
878 fprintf (rtl_dump_file, "Dead jumptable %i removed\n", INSN_UID (insn));
879 delete_insn (NEXT_INSN (insn));
880 delete_insn (insn);
881 next = NEXT_INSN (next);
886 /* Determine if the stack pointer is constant over the life of the function.
887 Only useful before prologues have been emitted. */
889 static void
890 notice_stack_pointer_modification_1 (rtx x, rtx pat ATTRIBUTE_UNUSED,
891 void *data ATTRIBUTE_UNUSED)
893 if (x == stack_pointer_rtx
894 /* The stack pointer is only modified indirectly as the result
895 of a push until later in flow. See the comments in rtl.texi
896 regarding Embedded Side-Effects on Addresses. */
897 || (GET_CODE (x) == MEM
898 && GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'a'
899 && XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
900 current_function_sp_is_unchanging = 0;
903 static void
904 notice_stack_pointer_modification (rtx f)
906 rtx insn;
908 /* Assume that the stack pointer is unchanging if alloca hasn't
909 been used. */
910 current_function_sp_is_unchanging = !current_function_calls_alloca;
911 if (! current_function_sp_is_unchanging)
912 return;
914 for (insn = f; insn; insn = NEXT_INSN (insn))
916 if (INSN_P (insn))
918 /* Check if insn modifies the stack pointer. */
919 note_stores (PATTERN (insn), notice_stack_pointer_modification_1,
920 NULL);
921 if (! current_function_sp_is_unchanging)
922 return;
927 /* Mark a register in SET. Hard registers in large modes get all
928 of their component registers set as well. */
930 static void
931 mark_reg (rtx reg, void *xset)
933 regset set = (regset) xset;
934 int regno = REGNO (reg);
936 if (GET_MODE (reg) == BLKmode)
937 abort ();
939 SET_REGNO_REG_SET (set, regno);
940 if (regno < FIRST_PSEUDO_REGISTER)
942 int n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
943 while (--n > 0)
944 SET_REGNO_REG_SET (set, regno + n);
948 /* Mark those regs which are needed at the end of the function as live
949 at the end of the last basic block. */
951 static void
952 mark_regs_live_at_end (regset set)
954 unsigned int i;
956 /* If exiting needs the right stack value, consider the stack pointer
957 live at the end of the function. */
958 if ((HAVE_epilogue && epilogue_completed)
959 || ! EXIT_IGNORE_STACK
960 || (! FRAME_POINTER_REQUIRED
961 && ! current_function_calls_alloca
962 && flag_omit_frame_pointer)
963 || current_function_sp_is_unchanging)
965 SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
968 /* Mark the frame pointer if needed at the end of the function. If
969 we end up eliminating it, it will be removed from the live list
970 of each basic block by reload. */
972 if (! reload_completed || frame_pointer_needed)
974 SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
975 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
976 /* If they are different, also mark the hard frame pointer as live. */
977 if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
978 SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
979 #endif
982 #ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
983 /* Many architectures have a GP register even without flag_pic.
984 Assume the pic register is not in use, or will be handled by
985 other means, if it is not fixed. */
986 if ((unsigned) PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
987 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
988 SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
989 #endif
991 /* Mark all global registers, and all registers used by the epilogue
992 as being live at the end of the function since they may be
993 referenced by our caller. */
994 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
995 if (global_regs[i] || EPILOGUE_USES (i))
996 SET_REGNO_REG_SET (set, i);
998 if (HAVE_epilogue && epilogue_completed)
1000 /* Mark all call-saved registers that we actually used. */
1001 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1002 if (regs_ever_live[i] && ! LOCAL_REGNO (i)
1003 && ! TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1004 SET_REGNO_REG_SET (set, i);
1007 #ifdef EH_RETURN_DATA_REGNO
1008 /* Mark the registers that will contain data for the handler. */
1009 if (reload_completed && current_function_calls_eh_return)
1010 for (i = 0; ; ++i)
1012 unsigned regno = EH_RETURN_DATA_REGNO(i);
1013 if (regno == INVALID_REGNUM)
1014 break;
1015 SET_REGNO_REG_SET (set, regno);
1017 #endif
1018 #ifdef EH_RETURN_STACKADJ_RTX
1019 if ((! HAVE_epilogue || ! epilogue_completed)
1020 && current_function_calls_eh_return)
1022 rtx tmp = EH_RETURN_STACKADJ_RTX;
1023 if (tmp && REG_P (tmp))
1024 mark_reg (tmp, set);
1026 #endif
1027 #ifdef EH_RETURN_HANDLER_RTX
1028 if ((! HAVE_epilogue || ! epilogue_completed)
1029 && current_function_calls_eh_return)
1031 rtx tmp = EH_RETURN_HANDLER_RTX;
1032 if (tmp && REG_P (tmp))
1033 mark_reg (tmp, set);
1035 #endif
1037 /* Mark function return value. */
1038 diddle_return_value (mark_reg, set);
1041 /* Propagate global life info around the graph of basic blocks. Begin
1042 considering blocks with their corresponding bit set in BLOCKS_IN.
1043 If BLOCKS_IN is null, consider it the universal set.
1045 BLOCKS_OUT is set for every block that was changed. */
1047 static void
1048 calculate_global_regs_live (sbitmap blocks_in, sbitmap blocks_out, int flags)
1050 basic_block *queue, *qhead, *qtail, *qend, bb;
1051 regset tmp, new_live_at_end, invalidated_by_call;
1052 regset_head tmp_head, invalidated_by_call_head;
1053 regset_head new_live_at_end_head;
1054 int i;
1056 /* Some passes used to forget clear aux field of basic block causing
1057 sick behavior here. */
1058 #ifdef ENABLE_CHECKING
1059 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1060 if (bb->aux)
1061 abort ();
1062 #endif
1064 tmp = INITIALIZE_REG_SET (tmp_head);
1065 new_live_at_end = INITIALIZE_REG_SET (new_live_at_end_head);
1066 invalidated_by_call = INITIALIZE_REG_SET (invalidated_by_call_head);
1068 /* Inconveniently, this is only readily available in hard reg set form. */
1069 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
1070 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
1071 SET_REGNO_REG_SET (invalidated_by_call, i);
1073 /* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
1074 because the `head == tail' style test for an empty queue doesn't
1075 work with a full queue. */
1076 queue = xmalloc ((n_basic_blocks + 2) * sizeof (*queue));
1077 qtail = queue;
1078 qhead = qend = queue + n_basic_blocks + 2;
1080 /* Queue the blocks set in the initial mask. Do this in reverse block
1081 number order so that we are more likely for the first round to do
1082 useful work. We use AUX non-null to flag that the block is queued. */
1083 if (blocks_in)
1085 FOR_EACH_BB (bb)
1086 if (TEST_BIT (blocks_in, bb->index))
1088 *--qhead = bb;
1089 bb->aux = bb;
1092 else
1094 FOR_EACH_BB (bb)
1096 *--qhead = bb;
1097 bb->aux = bb;
1101 /* We clean aux when we remove the initially-enqueued bbs, but we
1102 don't enqueue ENTRY and EXIT initially, so clean them upfront and
1103 unconditionally. */
1104 ENTRY_BLOCK_PTR->aux = EXIT_BLOCK_PTR->aux = NULL;
1106 if (blocks_out)
1107 sbitmap_zero (blocks_out);
1109 /* We work through the queue until there are no more blocks. What
1110 is live at the end of this block is precisely the union of what
1111 is live at the beginning of all its successors. So, we set its
1112 GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
1113 for its successors. Then, we compute GLOBAL_LIVE_AT_START for
1114 this block by walking through the instructions in this block in
1115 reverse order and updating as we go. If that changed
1116 GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
1117 queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
1119 We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
1120 never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
1121 must either be live at the end of the block, or used within the
1122 block. In the latter case, it will certainly never disappear
1123 from GLOBAL_LIVE_AT_START. In the former case, the register
1124 could go away only if it disappeared from GLOBAL_LIVE_AT_START
1125 for one of the successor blocks. By induction, that cannot
1126 occur. */
1127 while (qhead != qtail)
1129 int rescan, changed;
1130 basic_block bb;
1131 edge e;
1133 bb = *qhead++;
1134 if (qhead == qend)
1135 qhead = queue;
1136 bb->aux = NULL;
1138 /* Begin by propagating live_at_start from the successor blocks. */
1139 CLEAR_REG_SET (new_live_at_end);
1141 if (bb->succ)
1142 for (e = bb->succ; e; e = e->succ_next)
1144 basic_block sb = e->dest;
1146 /* Call-clobbered registers die across exception and
1147 call edges. */
1148 /* ??? Abnormal call edges ignored for the moment, as this gets
1149 confused by sibling call edges, which crashes reg-stack. */
1150 if (e->flags & EDGE_EH)
1152 bitmap_operation (tmp, sb->global_live_at_start,
1153 invalidated_by_call, BITMAP_AND_COMPL);
1154 IOR_REG_SET (new_live_at_end, tmp);
1156 else
1157 IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
1159 /* If a target saves one register in another (instead of on
1160 the stack) the save register will need to be live for EH. */
1161 if (e->flags & EDGE_EH)
1162 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1163 if (EH_USES (i))
1164 SET_REGNO_REG_SET (new_live_at_end, i);
1166 else
1168 /* This might be a noreturn function that throws. And
1169 even if it isn't, getting the unwind info right helps
1170 debugging. */
1171 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1172 if (EH_USES (i))
1173 SET_REGNO_REG_SET (new_live_at_end, i);
1176 /* The all-important stack pointer must always be live. */
1177 SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
1179 /* Before reload, there are a few registers that must be forced
1180 live everywhere -- which might not already be the case for
1181 blocks within infinite loops. */
1182 if (! reload_completed)
1184 /* Any reference to any pseudo before reload is a potential
1185 reference of the frame pointer. */
1186 SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
1188 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1189 /* Pseudos with argument area equivalences may require
1190 reloading via the argument pointer. */
1191 if (fixed_regs[ARG_POINTER_REGNUM])
1192 SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
1193 #endif
1195 /* Any constant, or pseudo with constant equivalences, may
1196 require reloading from memory using the pic register. */
1197 if ((unsigned) PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
1198 && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
1199 SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
1202 if (bb == ENTRY_BLOCK_PTR)
1204 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1205 continue;
1208 /* On our first pass through this block, we'll go ahead and continue.
1209 Recognize first pass by local_set NULL. On subsequent passes, we
1210 get to skip out early if live_at_end wouldn't have changed. */
1212 if (bb->local_set == NULL)
1214 bb->local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1215 bb->cond_local_set = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1216 rescan = 1;
1218 else
1220 /* If any bits were removed from live_at_end, we'll have to
1221 rescan the block. This wouldn't be necessary if we had
1222 precalculated local_live, however with PROP_SCAN_DEAD_CODE
1223 local_live is really dependent on live_at_end. */
1224 CLEAR_REG_SET (tmp);
1225 rescan = bitmap_operation (tmp, bb->global_live_at_end,
1226 new_live_at_end, BITMAP_AND_COMPL);
1228 if (! rescan)
1230 /* If any of the registers in the new live_at_end set are
1231 conditionally set in this basic block, we must rescan.
1232 This is because conditional lifetimes at the end of the
1233 block do not just take the live_at_end set into account,
1234 but also the liveness at the start of each successor
1235 block. We can miss changes in those sets if we only
1236 compare the new live_at_end against the previous one. */
1237 CLEAR_REG_SET (tmp);
1238 rescan = bitmap_operation (tmp, new_live_at_end,
1239 bb->cond_local_set, BITMAP_AND);
1242 if (! rescan)
1244 /* Find the set of changed bits. Take this opportunity
1245 to notice that this set is empty and early out. */
1246 CLEAR_REG_SET (tmp);
1247 changed = bitmap_operation (tmp, bb->global_live_at_end,
1248 new_live_at_end, BITMAP_XOR);
1249 if (! changed)
1250 continue;
1252 /* If any of the changed bits overlap with local_set,
1253 we'll have to rescan the block. Detect overlap by
1254 the AND with ~local_set turning off bits. */
1255 rescan = bitmap_operation (tmp, tmp, bb->local_set,
1256 BITMAP_AND_COMPL);
1260 /* Let our caller know that BB changed enough to require its
1261 death notes updated. */
1262 if (blocks_out)
1263 SET_BIT (blocks_out, bb->index);
1265 if (! rescan)
1267 /* Add to live_at_start the set of all registers in
1268 new_live_at_end that aren't in the old live_at_end. */
1270 bitmap_operation (tmp, new_live_at_end, bb->global_live_at_end,
1271 BITMAP_AND_COMPL);
1272 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1274 changed = bitmap_operation (bb->global_live_at_start,
1275 bb->global_live_at_start,
1276 tmp, BITMAP_IOR);
1277 if (! changed)
1278 continue;
1280 else
1282 COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
1284 /* Rescan the block insn by insn to turn (a copy of) live_at_end
1285 into live_at_start. */
1286 propagate_block (bb, new_live_at_end, bb->local_set,
1287 bb->cond_local_set, flags);
1289 /* If live_at start didn't change, no need to go farther. */
1290 if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
1291 continue;
1293 COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
1296 /* Queue all predecessors of BB so that we may re-examine
1297 their live_at_end. */
1298 for (e = bb->pred; e; e = e->pred_next)
1300 basic_block pb = e->src;
1301 if (pb->aux == NULL)
1303 *qtail++ = pb;
1304 if (qtail == qend)
1305 qtail = queue;
1306 pb->aux = pb;
1311 FREE_REG_SET (tmp);
1312 FREE_REG_SET (new_live_at_end);
1313 FREE_REG_SET (invalidated_by_call);
1315 if (blocks_out)
1317 EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
1319 basic_block bb = BASIC_BLOCK (i);
1320 FREE_REG_SET (bb->local_set);
1321 FREE_REG_SET (bb->cond_local_set);
1324 else
1326 FOR_EACH_BB (bb)
1328 FREE_REG_SET (bb->local_set);
1329 FREE_REG_SET (bb->cond_local_set);
1333 free (queue);
1337 /* This structure is used to pass parameters to and from the
1338 the function find_regno_partial(). It is used to pass in the
1339 register number we are looking, as well as to return any rtx
1340 we find. */
1342 typedef struct {
1343 unsigned regno_to_find;
1344 rtx retval;
1345 } find_regno_partial_param;
1348 /* Find the rtx for the reg numbers specified in 'data' if it is
1349 part of an expression which only uses part of the register. Return
1350 it in the structure passed in. */
1351 static int
1352 find_regno_partial (rtx *ptr, void *data)
1354 find_regno_partial_param *param = (find_regno_partial_param *)data;
1355 unsigned reg = param->regno_to_find;
1356 param->retval = NULL_RTX;
1358 if (*ptr == NULL_RTX)
1359 return 0;
1361 switch (GET_CODE (*ptr))
1363 case ZERO_EXTRACT:
1364 case SIGN_EXTRACT:
1365 case STRICT_LOW_PART:
1366 if (GET_CODE (XEXP (*ptr, 0)) == REG && REGNO (XEXP (*ptr, 0)) == reg)
1368 param->retval = XEXP (*ptr, 0);
1369 return 1;
1371 break;
1373 case SUBREG:
1374 if (GET_CODE (SUBREG_REG (*ptr)) == REG
1375 && REGNO (SUBREG_REG (*ptr)) == reg)
1377 param->retval = SUBREG_REG (*ptr);
1378 return 1;
1380 break;
1382 default:
1383 break;
1386 return 0;
1389 /* Process all immediate successors of the entry block looking for pseudo
1390 registers which are live on entry. Find all of those whose first
1391 instance is a partial register reference of some kind, and initialize
1392 them to 0 after the entry block. This will prevent bit sets within
1393 registers whose value is unknown, and may contain some kind of sticky
1394 bits we don't want. */
1397 initialize_uninitialized_subregs (void)
1399 rtx insn;
1400 edge e;
1401 int reg, did_something = 0;
1402 find_regno_partial_param param;
1404 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
1406 basic_block bb = e->dest;
1407 regset map = bb->global_live_at_start;
1408 EXECUTE_IF_SET_IN_REG_SET (map,
1409 FIRST_PSEUDO_REGISTER, reg,
1411 int uid = REGNO_FIRST_UID (reg);
1412 rtx i;
1414 /* Find an insn which mentions the register we are looking for.
1415 Its preferable to have an instance of the register's rtl since
1416 there may be various flags set which we need to duplicate.
1417 If we can't find it, its probably an automatic whose initial
1418 value doesn't matter, or hopefully something we don't care about. */
1419 for (i = get_insns (); i && INSN_UID (i) != uid; i = NEXT_INSN (i))
1421 if (i != NULL_RTX)
1423 /* Found the insn, now get the REG rtx, if we can. */
1424 param.regno_to_find = reg;
1425 for_each_rtx (&i, find_regno_partial, &param);
1426 if (param.retval != NULL_RTX)
1428 start_sequence ();
1429 emit_move_insn (param.retval,
1430 CONST0_RTX (GET_MODE (param.retval)));
1431 insn = get_insns ();
1432 end_sequence ();
1433 insert_insn_on_edge (insn, e);
1434 did_something = 1;
1440 if (did_something)
1441 commit_edge_insertions ();
1442 return did_something;
1446 /* Subroutines of life analysis. */
1448 /* Allocate the permanent data structures that represent the results
1449 of life analysis. Not static since used also for stupid life analysis. */
1451 void
1452 allocate_bb_life_data (void)
1454 basic_block bb;
1456 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
1458 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1459 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1462 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1465 void
1466 allocate_reg_life_data (void)
1468 int i;
1470 max_regno = max_reg_num ();
1472 /* Recalculate the register space, in case it has grown. Old style
1473 vector oriented regsets would set regset_{size,bytes} here also. */
1474 allocate_reg_info (max_regno, FALSE, FALSE);
1476 /* Reset all the data we'll collect in propagate_block and its
1477 subroutines. */
1478 for (i = 0; i < max_regno; i++)
1480 REG_N_SETS (i) = 0;
1481 REG_N_REFS (i) = 0;
1482 REG_N_DEATHS (i) = 0;
1483 REG_N_CALLS_CROSSED (i) = 0;
1484 REG_LIVE_LENGTH (i) = 0;
1485 REG_FREQ (i) = 0;
1486 REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
1490 /* Delete dead instructions for propagate_block. */
1492 static void
1493 propagate_block_delete_insn (rtx insn)
1495 rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
1497 /* If the insn referred to a label, and that label was attached to
1498 an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
1499 pretty much mandatory to delete it, because the ADDR_VEC may be
1500 referencing labels that no longer exist.
1502 INSN may reference a deleted label, particularly when a jump
1503 table has been optimized into a direct jump. There's no
1504 real good way to fix up the reference to the deleted label
1505 when the label is deleted, so we just allow it here. */
1507 if (inote && GET_CODE (inote) == CODE_LABEL)
1509 rtx label = XEXP (inote, 0);
1510 rtx next;
1512 /* The label may be forced if it has been put in the constant
1513 pool. If that is the only use we must discard the table
1514 jump following it, but not the label itself. */
1515 if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
1516 && (next = next_nonnote_insn (label)) != NULL
1517 && GET_CODE (next) == JUMP_INSN
1518 && (GET_CODE (PATTERN (next)) == ADDR_VEC
1519 || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
1521 rtx pat = PATTERN (next);
1522 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
1523 int len = XVECLEN (pat, diff_vec_p);
1524 int i;
1526 for (i = 0; i < len; i++)
1527 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
1529 delete_insn_and_edges (next);
1530 ndead++;
1534 delete_insn_and_edges (insn);
1535 ndead++;
1538 /* Delete dead libcalls for propagate_block. Return the insn
1539 before the libcall. */
1541 static rtx
1542 propagate_block_delete_libcall (rtx insn, rtx note)
1544 rtx first = XEXP (note, 0);
1545 rtx before = PREV_INSN (first);
1547 delete_insn_chain_and_edges (first, insn);
1548 ndead++;
1549 return before;
1552 /* Update the life-status of regs for one insn. Return the previous insn. */
1555 propagate_one_insn (struct propagate_block_info *pbi, rtx insn)
1557 rtx prev = PREV_INSN (insn);
1558 int flags = pbi->flags;
1559 int insn_is_dead = 0;
1560 int libcall_is_dead = 0;
1561 rtx note;
1562 int i;
1564 if (! INSN_P (insn))
1565 return prev;
1567 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1568 if (flags & PROP_SCAN_DEAD_CODE)
1570 insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
1571 libcall_is_dead = (insn_is_dead && note != 0
1572 && libcall_dead_p (pbi, note, insn));
1575 /* If an instruction consists of just dead store(s) on final pass,
1576 delete it. */
1577 if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
1579 /* If we're trying to delete a prologue or epilogue instruction
1580 that isn't flagged as possibly being dead, something is wrong.
1581 But if we are keeping the stack pointer depressed, we might well
1582 be deleting insns that are used to compute the amount to update
1583 it by, so they are fine. */
1584 if (reload_completed
1585 && !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1586 && (TYPE_RETURNS_STACK_DEPRESSED
1587 (TREE_TYPE (current_function_decl))))
1588 && (((HAVE_epilogue || HAVE_prologue)
1589 && prologue_epilogue_contains (insn))
1590 || (HAVE_sibcall_epilogue
1591 && sibcall_epilogue_contains (insn)))
1592 && find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
1593 fatal_insn ("Attempt to delete prologue/epilogue insn:", insn);
1595 /* Record sets. Do this even for dead instructions, since they
1596 would have killed the values if they hadn't been deleted. */
1597 mark_set_regs (pbi, PATTERN (insn), insn);
1599 /* CC0 is now known to be dead. Either this insn used it,
1600 in which case it doesn't anymore, or clobbered it,
1601 so the next insn can't use it. */
1602 pbi->cc0_live = 0;
1604 if (libcall_is_dead)
1605 prev = propagate_block_delete_libcall ( insn, note);
1606 else
1609 /* If INSN contains a RETVAL note and is dead, but the libcall
1610 as a whole is not dead, then we want to remove INSN, but
1611 not the whole libcall sequence.
1613 However, we need to also remove the dangling REG_LIBCALL
1614 note so that we do not have mis-matched LIBCALL/RETVAL
1615 notes. In theory we could find a new location for the
1616 REG_RETVAL note, but it hardly seems worth the effort.
1618 NOTE at this point will be the RETVAL note if it exists. */
1619 if (note)
1621 rtx libcall_note;
1623 libcall_note
1624 = find_reg_note (XEXP (note, 0), REG_LIBCALL, NULL_RTX);
1625 remove_note (XEXP (note, 0), libcall_note);
1628 /* Similarly if INSN contains a LIBCALL note, remove the
1629 dangling REG_RETVAL note. */
1630 note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
1631 if (note)
1633 rtx retval_note;
1635 retval_note
1636 = find_reg_note (XEXP (note, 0), REG_RETVAL, NULL_RTX);
1637 remove_note (XEXP (note, 0), retval_note);
1640 /* Now delete INSN. */
1641 propagate_block_delete_insn (insn);
1644 return prev;
1647 /* See if this is an increment or decrement that can be merged into
1648 a following memory address. */
1649 #ifdef AUTO_INC_DEC
1651 rtx x = single_set (insn);
1653 /* Does this instruction increment or decrement a register? */
1654 if ((flags & PROP_AUTOINC)
1655 && x != 0
1656 && GET_CODE (SET_DEST (x)) == REG
1657 && (GET_CODE (SET_SRC (x)) == PLUS
1658 || GET_CODE (SET_SRC (x)) == MINUS)
1659 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1660 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1661 /* Ok, look for a following memory ref we can combine with.
1662 If one is found, change the memory ref to a PRE_INC
1663 or PRE_DEC, cancel this insn, and return 1.
1664 Return 0 if nothing has been done. */
1665 && try_pre_increment_1 (pbi, insn))
1666 return prev;
1668 #endif /* AUTO_INC_DEC */
1670 CLEAR_REG_SET (pbi->new_set);
1672 /* If this is not the final pass, and this insn is copying the value of
1673 a library call and it's dead, don't scan the insns that perform the
1674 library call, so that the call's arguments are not marked live. */
1675 if (libcall_is_dead)
1677 /* Record the death of the dest reg. */
1678 mark_set_regs (pbi, PATTERN (insn), insn);
1680 insn = XEXP (note, 0);
1681 return PREV_INSN (insn);
1683 else if (GET_CODE (PATTERN (insn)) == SET
1684 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1685 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1686 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1687 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1688 /* We have an insn to pop a constant amount off the stack.
1689 (Such insns use PLUS regardless of the direction of the stack,
1690 and any insn to adjust the stack by a constant is always a pop.)
1691 These insns, if not dead stores, have no effect on life, though
1692 they do have an effect on the memory stores we are tracking. */
1693 invalidate_mems_from_set (pbi, stack_pointer_rtx);
1694 else
1696 rtx note;
1697 /* Any regs live at the time of a call instruction must not go
1698 in a register clobbered by calls. Find all regs now live and
1699 record this for them. */
1701 if (GET_CODE (insn) == CALL_INSN && (flags & PROP_REG_INFO))
1702 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
1703 { REG_N_CALLS_CROSSED (i)++; });
1705 /* Record sets. Do this even for dead instructions, since they
1706 would have killed the values if they hadn't been deleted. */
1707 mark_set_regs (pbi, PATTERN (insn), insn);
1709 if (GET_CODE (insn) == CALL_INSN)
1711 regset live_at_end;
1712 bool sibcall_p;
1713 rtx note, cond;
1714 int i;
1716 cond = NULL_RTX;
1717 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1718 cond = COND_EXEC_TEST (PATTERN (insn));
1720 /* Non-constant calls clobber memory, constant calls do not
1721 clobber memory, though they may clobber outgoing arguments
1722 on the stack. */
1723 if (! CONST_OR_PURE_CALL_P (insn))
1725 free_EXPR_LIST_list (&pbi->mem_set_list);
1726 pbi->mem_set_list_len = 0;
1728 else
1729 invalidate_mems_from_set (pbi, stack_pointer_rtx);
1731 /* There may be extra registers to be clobbered. */
1732 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1733 note;
1734 note = XEXP (note, 1))
1735 if (GET_CODE (XEXP (note, 0)) == CLOBBER)
1736 mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
1737 cond, insn, pbi->flags);
1739 /* Calls change all call-used and global registers; sibcalls do not
1740 clobber anything that must be preserved at end-of-function,
1741 except for return values. */
1743 sibcall_p = SIBLING_CALL_P (insn);
1744 live_at_end = EXIT_BLOCK_PTR->global_live_at_start;
1745 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1746 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i)
1747 && ! (sibcall_p
1748 && REGNO_REG_SET_P (live_at_end, i)
1749 && ! refers_to_regno_p (i, i+1,
1750 current_function_return_rtx,
1751 (rtx *) 0)))
1753 /* We do not want REG_UNUSED notes for these registers. */
1754 mark_set_1 (pbi, CLOBBER, regno_reg_rtx[i], cond, insn,
1755 pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
1759 /* If an insn doesn't use CC0, it becomes dead since we assume
1760 that every insn clobbers it. So show it dead here;
1761 mark_used_regs will set it live if it is referenced. */
1762 pbi->cc0_live = 0;
1764 /* Record uses. */
1765 if (! insn_is_dead)
1766 mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
1767 if ((flags & PROP_EQUAL_NOTES)
1768 && ((note = find_reg_note (insn, REG_EQUAL, NULL_RTX))
1769 || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX))))
1770 mark_used_regs (pbi, XEXP (note, 0), NULL_RTX, insn);
1772 /* Sometimes we may have inserted something before INSN (such as a move)
1773 when we make an auto-inc. So ensure we will scan those insns. */
1774 #ifdef AUTO_INC_DEC
1775 prev = PREV_INSN (insn);
1776 #endif
1778 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1780 int i;
1781 rtx note, cond;
1783 cond = NULL_RTX;
1784 if (GET_CODE (PATTERN (insn)) == COND_EXEC)
1785 cond = COND_EXEC_TEST (PATTERN (insn));
1787 /* Calls use their arguments, and may clobber memory which
1788 address involves some register. */
1789 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1790 note;
1791 note = XEXP (note, 1))
1792 /* We find USE or CLOBBER entities in a FUNCTION_USAGE list: both
1793 of which mark_used_regs knows how to handle. */
1794 mark_used_regs (pbi, XEXP (XEXP (note, 0), 0), cond, insn);
1796 /* The stack ptr is used (honorarily) by a CALL insn. */
1797 SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
1799 /* Calls may also reference any of the global registers,
1800 so they are made live. */
1801 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1802 if (global_regs[i])
1803 mark_used_reg (pbi, regno_reg_rtx[i], cond, insn);
1807 /* On final pass, update counts of how many insns in which each reg
1808 is live. */
1809 if (flags & PROP_REG_INFO)
1810 EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i,
1811 { REG_LIVE_LENGTH (i)++; });
1813 return prev;
1816 /* Initialize a propagate_block_info struct for public consumption.
1817 Note that the structure itself is opaque to this file, but that
1818 the user can use the regsets provided here. */
1820 struct propagate_block_info *
1821 init_propagate_block_info (basic_block bb, regset live, regset local_set,
1822 regset cond_local_set, int flags)
1824 struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
1826 pbi->bb = bb;
1827 pbi->reg_live = live;
1828 pbi->mem_set_list = NULL_RTX;
1829 pbi->mem_set_list_len = 0;
1830 pbi->local_set = local_set;
1831 pbi->cond_local_set = cond_local_set;
1832 pbi->cc0_live = 0;
1833 pbi->flags = flags;
1835 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
1836 pbi->reg_next_use = xcalloc (max_reg_num (), sizeof (rtx));
1837 else
1838 pbi->reg_next_use = NULL;
1840 pbi->new_set = BITMAP_XMALLOC ();
1842 #ifdef HAVE_conditional_execution
1843 pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
1844 free_reg_cond_life_info);
1845 pbi->reg_cond_reg = BITMAP_XMALLOC ();
1847 /* If this block ends in a conditional branch, for each register
1848 live from one side of the branch and not the other, record the
1849 register as conditionally dead. */
1850 if (GET_CODE (bb->end) == JUMP_INSN
1851 && any_condjump_p (bb->end))
1853 regset_head diff_head;
1854 regset diff = INITIALIZE_REG_SET (diff_head);
1855 basic_block bb_true, bb_false;
1856 int i;
1858 /* Identify the successor blocks. */
1859 bb_true = bb->succ->dest;
1860 if (bb->succ->succ_next != NULL)
1862 bb_false = bb->succ->succ_next->dest;
1864 if (bb->succ->flags & EDGE_FALLTHRU)
1866 basic_block t = bb_false;
1867 bb_false = bb_true;
1868 bb_true = t;
1870 else if (! (bb->succ->succ_next->flags & EDGE_FALLTHRU))
1871 abort ();
1873 else
1875 /* This can happen with a conditional jump to the next insn. */
1876 if (JUMP_LABEL (bb->end) != bb_true->head)
1877 abort ();
1879 /* Simplest way to do nothing. */
1880 bb_false = bb_true;
1883 /* Compute which register lead different lives in the successors. */
1884 if (bitmap_operation (diff, bb_true->global_live_at_start,
1885 bb_false->global_live_at_start, BITMAP_XOR))
1887 /* Extract the condition from the branch. */
1888 rtx set_src = SET_SRC (pc_set (bb->end));
1889 rtx cond_true = XEXP (set_src, 0);
1890 rtx reg = XEXP (cond_true, 0);
1892 if (GET_CODE (reg) == SUBREG)
1893 reg = SUBREG_REG (reg);
1895 /* We can only track conditional lifetimes if the condition is
1896 in the form of a comparison of a register against zero.
1897 If the condition is more complex than that, then it is safe
1898 not to record any information. */
1899 if (GET_CODE (reg) == REG
1900 && XEXP (cond_true, 1) == const0_rtx)
1902 rtx cond_false
1903 = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond_true)),
1904 GET_MODE (cond_true), XEXP (cond_true, 0),
1905 XEXP (cond_true, 1));
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
1917 (diff, 0, i,
1919 struct reg_cond_life_info *rcli;
1920 rtx cond;
1922 rcli = xmalloc (sizeof (*rcli));
1924 if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
1925 cond = cond_false;
1926 else
1927 cond = cond_true;
1928 rcli->condition = cond;
1929 rcli->stores = const0_rtx;
1930 rcli->orig_condition = cond;
1932 splay_tree_insert (pbi->reg_cond_dead, i,
1933 (splay_tree_value) rcli);
1938 FREE_REG_SET (diff);
1940 #endif
1942 /* If this block has no successors, any stores to the frame that aren't
1943 used later in the block are dead. So make a pass over the block
1944 recording any such that are made and show them dead at the end. We do
1945 a very conservative and simple job here. */
1946 if (optimize
1947 && ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
1948 && (TYPE_RETURNS_STACK_DEPRESSED
1949 (TREE_TYPE (current_function_decl))))
1950 && (flags & PROP_SCAN_DEAD_STORES)
1951 && (bb->succ == NULL
1952 || (bb->succ->succ_next == NULL
1953 && bb->succ->dest == EXIT_BLOCK_PTR
1954 && ! current_function_calls_eh_return)))
1956 rtx insn, set;
1957 for (insn = bb->end; insn != bb->head; insn = PREV_INSN (insn))
1958 if (GET_CODE (insn) == INSN
1959 && (set = single_set (insn))
1960 && GET_CODE (SET_DEST (set)) == MEM)
1962 rtx mem = SET_DEST (set);
1963 rtx canon_mem = canon_rtx (mem);
1965 if (XEXP (canon_mem, 0) == frame_pointer_rtx
1966 || (GET_CODE (XEXP (canon_mem, 0)) == PLUS
1967 && XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
1968 && GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
1969 add_to_mem_set_list (pbi, canon_mem);
1973 return pbi;
1976 /* Release a propagate_block_info struct. */
1978 void
1979 free_propagate_block_info (struct propagate_block_info *pbi)
1981 free_EXPR_LIST_list (&pbi->mem_set_list);
1983 BITMAP_XFREE (pbi->new_set);
1985 #ifdef HAVE_conditional_execution
1986 splay_tree_delete (pbi->reg_cond_dead);
1987 BITMAP_XFREE (pbi->reg_cond_reg);
1988 #endif
1990 if (pbi->reg_next_use)
1991 free (pbi->reg_next_use);
1993 free (pbi);
1996 /* Compute the registers live at the beginning of a basic block BB from
1997 those live at the end.
1999 When called, REG_LIVE contains those live at the end. On return, it
2000 contains those live at the beginning.
2002 LOCAL_SET, if non-null, will be set with all registers killed
2003 unconditionally by this basic block.
2004 Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
2005 killed conditionally by this basic block. If there is any unconditional
2006 set of a register, then the corresponding bit will be set in LOCAL_SET
2007 and cleared in COND_LOCAL_SET.
2008 It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
2009 case, the resulting set will be equal to the union of the two sets that
2010 would otherwise be computed.
2012 Return nonzero if an INSN is deleted (i.e. by dead code removal). */
2015 propagate_block (basic_block bb, regset live, regset local_set,
2016 regset cond_local_set, int flags)
2018 struct propagate_block_info *pbi;
2019 rtx insn, prev;
2020 int changed;
2022 pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
2024 if (flags & PROP_REG_INFO)
2026 int i;
2028 /* Process the regs live at the end of the block.
2029 Mark them as not local to any one basic block. */
2030 EXECUTE_IF_SET_IN_REG_SET (live, 0, i,
2031 { REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL; });
2034 /* Scan the block an insn at a time from end to beginning. */
2036 changed = 0;
2037 for (insn = bb->end;; insn = prev)
2039 /* If this is a call to `setjmp' et al, warn if any
2040 non-volatile datum is live. */
2041 if ((flags & PROP_REG_INFO)
2042 && GET_CODE (insn) == CALL_INSN
2043 && find_reg_note (insn, REG_SETJMP, NULL))
2044 IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
2046 prev = propagate_one_insn (pbi, insn);
2047 if (!prev)
2048 changed |= insn != get_insns ();
2049 else
2050 changed |= NEXT_INSN (prev) != insn;
2052 if (insn == bb->head)
2053 break;
2056 free_propagate_block_info (pbi);
2058 return changed;
2061 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
2062 (SET expressions whose destinations are registers dead after the insn).
2063 NEEDED is the regset that says which regs are alive after the insn.
2065 Unless CALL_OK is nonzero, an insn is needed if it contains a CALL.
2067 If X is the entire body of an insn, NOTES contains the reg notes
2068 pertaining to the insn. */
2070 static int
2071 insn_dead_p (struct propagate_block_info *pbi, rtx x, int call_ok,
2072 rtx notes ATTRIBUTE_UNUSED)
2074 enum rtx_code code = GET_CODE (x);
2076 /* Don't eliminate insns that may trap. */
2077 if (flag_non_call_exceptions && may_trap_p (x))
2078 return 0;
2080 #ifdef AUTO_INC_DEC
2081 /* As flow is invoked after combine, we must take existing AUTO_INC
2082 expressions into account. */
2083 for (; notes; notes = XEXP (notes, 1))
2085 if (REG_NOTE_KIND (notes) == REG_INC)
2087 int regno = REGNO (XEXP (notes, 0));
2089 /* Don't delete insns to set global regs. */
2090 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2091 || REGNO_REG_SET_P (pbi->reg_live, regno))
2092 return 0;
2095 #endif
2097 /* If setting something that's a reg or part of one,
2098 see if that register's altered value will be live. */
2100 if (code == SET)
2102 rtx r = SET_DEST (x);
2104 #ifdef HAVE_cc0
2105 if (GET_CODE (r) == CC0)
2106 return ! pbi->cc0_live;
2107 #endif
2109 /* A SET that is a subroutine call cannot be dead. */
2110 if (GET_CODE (SET_SRC (x)) == CALL)
2112 if (! call_ok)
2113 return 0;
2116 /* Don't eliminate loads from volatile memory or volatile asms. */
2117 else if (volatile_refs_p (SET_SRC (x)))
2118 return 0;
2120 if (GET_CODE (r) == MEM)
2122 rtx temp, canon_r;
2124 if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode)
2125 return 0;
2127 canon_r = canon_rtx (r);
2129 /* Walk the set of memory locations we are currently tracking
2130 and see if one is an identical match to this memory location.
2131 If so, this memory write is dead (remember, we're walking
2132 backwards from the end of the block to the start). Since
2133 rtx_equal_p does not check the alias set or flags, we also
2134 must have the potential for them to conflict (anti_dependence). */
2135 for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
2136 if (unchanging_anti_dependence (r, XEXP (temp, 0)))
2138 rtx mem = XEXP (temp, 0);
2140 if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0))
2141 && (GET_MODE_SIZE (GET_MODE (canon_r))
2142 <= GET_MODE_SIZE (GET_MODE (mem))))
2143 return 1;
2145 #ifdef AUTO_INC_DEC
2146 /* Check if memory reference matches an auto increment. Only
2147 post increment/decrement or modify are valid. */
2148 if (GET_MODE (mem) == GET_MODE (r)
2149 && (GET_CODE (XEXP (mem, 0)) == POST_DEC
2150 || GET_CODE (XEXP (mem, 0)) == POST_INC
2151 || GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
2152 && GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
2153 && rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
2154 return 1;
2155 #endif
2158 else
2160 while (GET_CODE (r) == SUBREG
2161 || GET_CODE (r) == STRICT_LOW_PART
2162 || GET_CODE (r) == ZERO_EXTRACT)
2163 r = XEXP (r, 0);
2165 if (GET_CODE (r) == REG)
2167 int regno = REGNO (r);
2169 /* Obvious. */
2170 if (REGNO_REG_SET_P (pbi->reg_live, regno))
2171 return 0;
2173 /* If this is a hard register, verify that subsequent
2174 words are not needed. */
2175 if (regno < FIRST_PSEUDO_REGISTER)
2177 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
2179 while (--n > 0)
2180 if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
2181 return 0;
2184 /* Don't delete insns to set global regs. */
2185 if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
2186 return 0;
2188 /* Make sure insns to set the stack pointer aren't deleted. */
2189 if (regno == STACK_POINTER_REGNUM)
2190 return 0;
2192 /* ??? These bits might be redundant with the force live bits
2193 in calculate_global_regs_live. We would delete from
2194 sequential sets; whether this actually affects real code
2195 for anything but the stack pointer I don't know. */
2196 /* Make sure insns to set the frame pointer aren't deleted. */
2197 if (regno == FRAME_POINTER_REGNUM
2198 && (! reload_completed || frame_pointer_needed))
2199 return 0;
2200 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2201 if (regno == HARD_FRAME_POINTER_REGNUM
2202 && (! reload_completed || frame_pointer_needed))
2203 return 0;
2204 #endif
2206 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2207 /* Make sure insns to set arg pointer are never deleted
2208 (if the arg pointer isn't fixed, there will be a USE
2209 for it, so we can treat it normally). */
2210 if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2211 return 0;
2212 #endif
2214 /* Otherwise, the set is dead. */
2215 return 1;
2220 /* If performing several activities, insn is dead if each activity
2221 is individually dead. Also, CLOBBERs and USEs can be ignored; a
2222 CLOBBER or USE that's inside a PARALLEL doesn't make the insn
2223 worth keeping. */
2224 else if (code == PARALLEL)
2226 int i = XVECLEN (x, 0);
2228 for (i--; i >= 0; i--)
2229 if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
2230 && GET_CODE (XVECEXP (x, 0, i)) != USE
2231 && ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
2232 return 0;
2234 return 1;
2237 /* A CLOBBER of a pseudo-register that is dead serves no purpose. That
2238 is not necessarily true for hard registers. */
2239 else if (code == CLOBBER && GET_CODE (XEXP (x, 0)) == REG
2240 && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
2241 && ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
2242 return 1;
2244 /* We do not check other CLOBBER or USE here. An insn consisting of just
2245 a CLOBBER or just a USE should not be deleted. */
2246 return 0;
2249 /* If INSN is the last insn in a libcall, and assuming INSN is dead,
2250 return 1 if the entire library call is dead.
2251 This is true if INSN copies a register (hard or pseudo)
2252 and if the hard return reg of the call insn is dead.
2253 (The caller should have tested the destination of the SET inside
2254 INSN already for death.)
2256 If this insn doesn't just copy a register, then we don't
2257 have an ordinary libcall. In that case, cse could not have
2258 managed to substitute the source for the dest later on,
2259 so we can assume the libcall is dead.
2261 PBI is the block info giving pseudoregs live before this insn.
2262 NOTE is the REG_RETVAL note of the insn. */
2264 static int
2265 libcall_dead_p (struct propagate_block_info *pbi, rtx note, rtx insn)
2267 rtx x = single_set (insn);
2269 if (x)
2271 rtx r = SET_SRC (x);
2273 if (GET_CODE (r) == REG)
2275 rtx call = XEXP (note, 0);
2276 rtx call_pat;
2277 int i;
2279 /* Find the call insn. */
2280 while (call != insn && GET_CODE (call) != CALL_INSN)
2281 call = NEXT_INSN (call);
2283 /* If there is none, do nothing special,
2284 since ordinary death handling can understand these insns. */
2285 if (call == insn)
2286 return 0;
2288 /* See if the hard reg holding the value is dead.
2289 If this is a PARALLEL, find the call within it. */
2290 call_pat = PATTERN (call);
2291 if (GET_CODE (call_pat) == PARALLEL)
2293 for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
2294 if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
2295 && GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
2296 break;
2298 /* This may be a library call that is returning a value
2299 via invisible pointer. Do nothing special, since
2300 ordinary death handling can understand these insns. */
2301 if (i < 0)
2302 return 0;
2304 call_pat = XVECEXP (call_pat, 0, i);
2307 return insn_dead_p (pbi, call_pat, 1, REG_NOTES (call));
2310 return 1;
2313 /* Return 1 if register REGNO was used before it was set, i.e. if it is
2314 live at function entry. Don't count global register variables, variables
2315 in registers that can be used for function arg passing, or variables in
2316 fixed hard registers. */
2319 regno_uninitialized (unsigned int regno)
2321 if (n_basic_blocks == 0
2322 || (regno < FIRST_PSEUDO_REGISTER
2323 && (global_regs[regno]
2324 || fixed_regs[regno]
2325 || FUNCTION_ARG_REGNO_P (regno))))
2326 return 0;
2328 return REGNO_REG_SET_P (ENTRY_BLOCK_PTR->global_live_at_end, regno);
2331 /* 1 if register REGNO was alive at a place where `setjmp' was called
2332 and was set more than once or is an argument.
2333 Such regs may be clobbered by `longjmp'. */
2336 regno_clobbered_at_setjmp (int regno)
2338 if (n_basic_blocks == 0)
2339 return 0;
2341 return ((REG_N_SETS (regno) > 1
2342 || REGNO_REG_SET_P (ENTRY_BLOCK_PTR->global_live_at_end, regno))
2343 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
2346 /* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
2347 maximal list size; look for overlaps in mode and select the largest. */
2348 static void
2349 add_to_mem_set_list (struct propagate_block_info *pbi, rtx mem)
2351 rtx i;
2353 /* We don't know how large a BLKmode store is, so we must not
2354 take them into consideration. */
2355 if (GET_MODE (mem) == BLKmode)
2356 return;
2358 for (i = pbi->mem_set_list; i ; i = XEXP (i, 1))
2360 rtx e = XEXP (i, 0);
2361 if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0)))
2363 if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e)))
2365 #ifdef AUTO_INC_DEC
2366 /* If we must store a copy of the mem, we can just modify
2367 the mode of the stored copy. */
2368 if (pbi->flags & PROP_AUTOINC)
2369 PUT_MODE (e, GET_MODE (mem));
2370 else
2371 #endif
2372 XEXP (i, 0) = mem;
2374 return;
2378 if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN)
2380 #ifdef AUTO_INC_DEC
2381 /* Store a copy of mem, otherwise the address may be
2382 scrogged by find_auto_inc. */
2383 if (pbi->flags & PROP_AUTOINC)
2384 mem = shallow_copy_rtx (mem);
2385 #endif
2386 pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
2387 pbi->mem_set_list_len++;
2391 /* INSN references memory, possibly using autoincrement addressing modes.
2392 Find any entries on the mem_set_list that need to be invalidated due
2393 to an address change. */
2395 static int
2396 invalidate_mems_from_autoinc (rtx *px, void *data)
2398 rtx x = *px;
2399 struct propagate_block_info *pbi = data;
2401 if (GET_RTX_CLASS (GET_CODE (x)) == 'a')
2403 invalidate_mems_from_set (pbi, XEXP (x, 0));
2404 return -1;
2407 return 0;
2410 /* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
2412 static void
2413 invalidate_mems_from_set (struct propagate_block_info *pbi, rtx exp)
2415 rtx temp = pbi->mem_set_list;
2416 rtx prev = NULL_RTX;
2417 rtx next;
2419 while (temp)
2421 next = XEXP (temp, 1);
2422 if (reg_overlap_mentioned_p (exp, XEXP (temp, 0)))
2424 /* Splice this entry out of the list. */
2425 if (prev)
2426 XEXP (prev, 1) = next;
2427 else
2428 pbi->mem_set_list = next;
2429 free_EXPR_LIST_node (temp);
2430 pbi->mem_set_list_len--;
2432 else
2433 prev = temp;
2434 temp = next;
2438 /* Process the registers that are set within X. Their bits are set to
2439 1 in the regset DEAD, because they are dead prior to this insn.
2441 If INSN is nonzero, it is the insn being processed.
2443 FLAGS is the set of operations to perform. */
2445 static void
2446 mark_set_regs (struct propagate_block_info *pbi, rtx x, rtx insn)
2448 rtx cond = NULL_RTX;
2449 rtx link;
2450 enum rtx_code code;
2451 int flags = pbi->flags;
2453 if (insn)
2454 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
2456 if (REG_NOTE_KIND (link) == REG_INC)
2457 mark_set_1 (pbi, SET, XEXP (link, 0),
2458 (GET_CODE (x) == COND_EXEC
2459 ? COND_EXEC_TEST (x) : NULL_RTX),
2460 insn, flags);
2462 retry:
2463 switch (code = GET_CODE (x))
2465 case SET:
2466 if (GET_CODE (XEXP (x, 1)) == ASM_OPERANDS)
2467 flags |= PROP_ASM_SCAN;
2468 /* Fall thru */
2469 case CLOBBER:
2470 mark_set_1 (pbi, code, SET_DEST (x), cond, insn, flags);
2471 return;
2473 case COND_EXEC:
2474 cond = COND_EXEC_TEST (x);
2475 x = COND_EXEC_CODE (x);
2476 goto retry;
2478 case PARALLEL:
2480 int i;
2482 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
2484 rtx sub = XVECEXP (x, 0, i);
2485 switch (code = GET_CODE (sub))
2487 case COND_EXEC:
2488 if (cond != NULL_RTX)
2489 abort ();
2491 cond = COND_EXEC_TEST (sub);
2492 sub = COND_EXEC_CODE (sub);
2493 if (GET_CODE (sub) == SET)
2494 goto mark_set;
2495 if (GET_CODE (sub) == CLOBBER)
2496 goto mark_clob;
2497 break;
2499 case SET:
2500 mark_set:
2501 if (GET_CODE (XEXP (sub, 1)) == ASM_OPERANDS)
2502 flags |= PROP_ASM_SCAN;
2503 /* Fall thru */
2504 case CLOBBER:
2505 mark_clob:
2506 mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, flags);
2507 break;
2509 default:
2510 break;
2513 break;
2516 default:
2517 break;
2521 /* Process a single set, which appears in INSN. REG (which may not
2522 actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
2523 being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
2524 If the set is conditional (because it appear in a COND_EXEC), COND
2525 will be the condition. */
2527 static void
2528 mark_set_1 (struct propagate_block_info *pbi, enum rtx_code code, rtx reg, rtx cond, rtx insn, int flags)
2530 int regno_first = -1, regno_last = -1;
2531 unsigned long not_dead = 0;
2532 int i;
2534 /* Modifying just one hardware register of a multi-reg value or just a
2535 byte field of a register does not mean the value from before this insn
2536 is now dead. Of course, if it was dead after it's unused now. */
2538 switch (GET_CODE (reg))
2540 case PARALLEL:
2541 /* Some targets place small structures in registers for return values of
2542 functions. We have to detect this case specially here to get correct
2543 flow information. */
2544 for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
2545 if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
2546 mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
2547 flags);
2548 return;
2550 case ZERO_EXTRACT:
2551 case SIGN_EXTRACT:
2552 case STRICT_LOW_PART:
2553 /* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
2555 reg = XEXP (reg, 0);
2556 while (GET_CODE (reg) == SUBREG
2557 || GET_CODE (reg) == ZERO_EXTRACT
2558 || GET_CODE (reg) == SIGN_EXTRACT
2559 || GET_CODE (reg) == STRICT_LOW_PART);
2560 if (GET_CODE (reg) == MEM)
2561 break;
2562 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
2563 /* Fall through. */
2565 case REG:
2566 regno_last = regno_first = REGNO (reg);
2567 if (regno_first < FIRST_PSEUDO_REGISTER)
2568 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
2569 break;
2571 case SUBREG:
2572 if (GET_CODE (SUBREG_REG (reg)) == REG)
2574 enum machine_mode outer_mode = GET_MODE (reg);
2575 enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
2577 /* Identify the range of registers affected. This is moderately
2578 tricky for hard registers. See alter_subreg. */
2580 regno_last = regno_first = REGNO (SUBREG_REG (reg));
2581 if (regno_first < FIRST_PSEUDO_REGISTER)
2583 regno_first += subreg_regno_offset (regno_first, inner_mode,
2584 SUBREG_BYTE (reg),
2585 outer_mode);
2586 regno_last = (regno_first
2587 + HARD_REGNO_NREGS (regno_first, outer_mode) - 1);
2589 /* Since we've just adjusted the register number ranges, make
2590 sure REG matches. Otherwise some_was_live will be clear
2591 when it shouldn't have been, and we'll create incorrect
2592 REG_UNUSED notes. */
2593 reg = gen_rtx_REG (outer_mode, regno_first);
2595 else
2597 /* If the number of words in the subreg is less than the number
2598 of words in the full register, we have a well-defined partial
2599 set. Otherwise the high bits are undefined.
2601 This is only really applicable to pseudos, since we just took
2602 care of multi-word hard registers. */
2603 if (((GET_MODE_SIZE (outer_mode)
2604 + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
2605 < ((GET_MODE_SIZE (inner_mode)
2606 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
2607 not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
2608 regno_first);
2610 reg = SUBREG_REG (reg);
2613 else
2614 reg = SUBREG_REG (reg);
2615 break;
2617 default:
2618 break;
2621 /* If this set is a MEM, then it kills any aliased writes.
2622 If this set is a REG, then it kills any MEMs which use the reg. */
2623 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
2625 if (GET_CODE (reg) == REG)
2626 invalidate_mems_from_set (pbi, reg);
2628 /* If the memory reference had embedded side effects (autoincrement
2629 address modes. Then we may need to kill some entries on the
2630 memory set list. */
2631 if (insn && GET_CODE (reg) == MEM)
2632 for_each_rtx (&PATTERN (insn), invalidate_mems_from_autoinc, pbi);
2634 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
2635 /* ??? With more effort we could track conditional memory life. */
2636 && ! cond)
2637 add_to_mem_set_list (pbi, canon_rtx (reg));
2640 if (GET_CODE (reg) == REG
2641 && ! (regno_first == FRAME_POINTER_REGNUM
2642 && (! reload_completed || frame_pointer_needed))
2643 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2644 && ! (regno_first == HARD_FRAME_POINTER_REGNUM
2645 && (! reload_completed || frame_pointer_needed))
2646 #endif
2647 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2648 && ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
2649 #endif
2652 int some_was_live = 0, some_was_dead = 0;
2654 for (i = regno_first; i <= regno_last; ++i)
2656 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
2657 if (pbi->local_set)
2659 /* Order of the set operation matters here since both
2660 sets may be the same. */
2661 CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
2662 if (cond != NULL_RTX
2663 && ! REGNO_REG_SET_P (pbi->local_set, i))
2664 SET_REGNO_REG_SET (pbi->cond_local_set, i);
2665 else
2666 SET_REGNO_REG_SET (pbi->local_set, i);
2668 if (code != CLOBBER)
2669 SET_REGNO_REG_SET (pbi->new_set, i);
2671 some_was_live |= needed_regno;
2672 some_was_dead |= ! needed_regno;
2675 #ifdef HAVE_conditional_execution
2676 /* Consider conditional death in deciding that the register needs
2677 a death note. */
2678 if (some_was_live && ! not_dead
2679 /* The stack pointer is never dead. Well, not strictly true,
2680 but it's very difficult to tell from here. Hopefully
2681 combine_stack_adjustments will fix up the most egregious
2682 errors. */
2683 && regno_first != STACK_POINTER_REGNUM)
2685 for (i = regno_first; i <= regno_last; ++i)
2686 if (! mark_regno_cond_dead (pbi, i, cond))
2687 not_dead |= ((unsigned long) 1) << (i - regno_first);
2689 #endif
2691 /* Additional data to record if this is the final pass. */
2692 if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
2693 | PROP_DEATH_NOTES | PROP_AUTOINC))
2695 rtx y;
2696 int blocknum = pbi->bb->index;
2698 y = NULL_RTX;
2699 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2701 y = pbi->reg_next_use[regno_first];
2703 /* The next use is no longer next, since a store intervenes. */
2704 for (i = regno_first; i <= regno_last; ++i)
2705 pbi->reg_next_use[i] = 0;
2708 if (flags & PROP_REG_INFO)
2710 for (i = regno_first; i <= regno_last; ++i)
2712 /* Count (weighted) references, stores, etc. This counts a
2713 register twice if it is modified, but that is correct. */
2714 REG_N_SETS (i) += 1;
2715 REG_N_REFS (i) += 1;
2716 REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb);
2718 /* The insns where a reg is live are normally counted
2719 elsewhere, but we want the count to include the insn
2720 where the reg is set, and the normal counting mechanism
2721 would not count it. */
2722 REG_LIVE_LENGTH (i) += 1;
2725 /* If this is a hard reg, record this function uses the reg. */
2726 if (regno_first < FIRST_PSEUDO_REGISTER)
2728 for (i = regno_first; i <= regno_last; i++)
2729 regs_ever_live[i] = 1;
2730 if (flags & PROP_ASM_SCAN)
2731 for (i = regno_first; i <= regno_last; i++)
2732 regs_asm_clobbered[i] = 1;
2734 else
2736 /* Keep track of which basic blocks each reg appears in. */
2737 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
2738 REG_BASIC_BLOCK (regno_first) = blocknum;
2739 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
2740 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
2744 if (! some_was_dead)
2746 if (flags & PROP_LOG_LINKS)
2748 /* Make a logical link from the next following insn
2749 that uses this register, back to this insn.
2750 The following insns have already been processed.
2752 We don't build a LOG_LINK for hard registers containing
2753 in ASM_OPERANDs. If these registers get replaced,
2754 we might wind up changing the semantics of the insn,
2755 even if reload can make what appear to be valid
2756 assignments later. */
2757 if (y && (BLOCK_NUM (y) == blocknum)
2758 && (regno_first >= FIRST_PSEUDO_REGISTER
2759 || asm_noperands (PATTERN (y)) < 0))
2760 LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
2763 else if (not_dead)
2765 else if (! some_was_live)
2767 if (flags & PROP_REG_INFO)
2768 REG_N_DEATHS (regno_first) += 1;
2770 if (flags & PROP_DEATH_NOTES)
2772 /* Note that dead stores have already been deleted
2773 when possible. If we get here, we have found a
2774 dead store that cannot be eliminated (because the
2775 same insn does something useful). Indicate this
2776 by marking the reg being set as dying here. */
2777 REG_NOTES (insn)
2778 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2781 else
2783 if (flags & PROP_DEATH_NOTES)
2785 /* This is a case where we have a multi-word hard register
2786 and some, but not all, of the words of the register are
2787 needed in subsequent insns. Write REG_UNUSED notes
2788 for those parts that were not needed. This case should
2789 be rare. */
2791 for (i = regno_first; i <= regno_last; ++i)
2792 if (! REGNO_REG_SET_P (pbi->reg_live, i))
2793 REG_NOTES (insn)
2794 = alloc_EXPR_LIST (REG_UNUSED,
2795 regno_reg_rtx[i],
2796 REG_NOTES (insn));
2801 /* Mark the register as being dead. */
2802 if (some_was_live
2803 /* The stack pointer is never dead. Well, not strictly true,
2804 but it's very difficult to tell from here. Hopefully
2805 combine_stack_adjustments will fix up the most egregious
2806 errors. */
2807 && regno_first != STACK_POINTER_REGNUM)
2809 for (i = regno_first; i <= regno_last; ++i)
2810 if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
2811 CLEAR_REGNO_REG_SET (pbi->reg_live, i);
2814 else if (GET_CODE (reg) == REG)
2816 if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
2817 pbi->reg_next_use[regno_first] = 0;
2819 if ((flags & PROP_REG_INFO) != 0
2820 && (flags & PROP_ASM_SCAN) != 0
2821 && regno_first < FIRST_PSEUDO_REGISTER)
2823 for (i = regno_first; i <= regno_last; i++)
2824 regs_asm_clobbered[i] = 1;
2828 /* If this is the last pass and this is a SCRATCH, show it will be dying
2829 here and count it. */
2830 else if (GET_CODE (reg) == SCRATCH)
2832 if (flags & PROP_DEATH_NOTES)
2833 REG_NOTES (insn)
2834 = alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
2838 #ifdef HAVE_conditional_execution
2839 /* Mark REGNO conditionally dead.
2840 Return true if the register is now unconditionally dead. */
2842 static int
2843 mark_regno_cond_dead (struct propagate_block_info *pbi, int regno, rtx cond)
2845 /* If this is a store to a predicate register, the value of the
2846 predicate is changing, we don't know that the predicate as seen
2847 before is the same as that seen after. Flush all dependent
2848 conditions from reg_cond_dead. This will make all such
2849 conditionally live registers unconditionally live. */
2850 if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
2851 flush_reg_cond_reg (pbi, regno);
2853 /* If this is an unconditional store, remove any conditional
2854 life that may have existed. */
2855 if (cond == NULL_RTX)
2856 splay_tree_remove (pbi->reg_cond_dead, regno);
2857 else
2859 splay_tree_node node;
2860 struct reg_cond_life_info *rcli;
2861 rtx ncond;
2863 /* Otherwise this is a conditional set. Record that fact.
2864 It may have been conditionally used, or there may be a
2865 subsequent set with a complimentary condition. */
2867 node = splay_tree_lookup (pbi->reg_cond_dead, regno);
2868 if (node == NULL)
2870 /* The register was unconditionally live previously.
2871 Record the current condition as the condition under
2872 which it is dead. */
2873 rcli = xmalloc (sizeof (*rcli));
2874 rcli->condition = cond;
2875 rcli->stores = cond;
2876 rcli->orig_condition = const0_rtx;
2877 splay_tree_insert (pbi->reg_cond_dead, regno,
2878 (splay_tree_value) rcli);
2880 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2882 /* Not unconditionally dead. */
2883 return 0;
2885 else
2887 /* The register was conditionally live previously.
2888 Add the new condition to the old. */
2889 rcli = (struct reg_cond_life_info *) node->value;
2890 ncond = rcli->condition;
2891 ncond = ior_reg_cond (ncond, cond, 1);
2892 if (rcli->stores == const0_rtx)
2893 rcli->stores = cond;
2894 else if (rcli->stores != const1_rtx)
2895 rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
2897 /* If the register is now unconditionally dead, remove the entry
2898 in the splay_tree. A register is unconditionally dead if the
2899 dead condition ncond is true. A register is also unconditionally
2900 dead if the sum of all conditional stores is an unconditional
2901 store (stores is true), and the dead condition is identically the
2902 same as the original dead condition initialized at the end of
2903 the block. This is a pointer compare, not an rtx_equal_p
2904 compare. */
2905 if (ncond == const1_rtx
2906 || (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
2907 splay_tree_remove (pbi->reg_cond_dead, regno);
2908 else
2910 rcli->condition = ncond;
2912 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
2914 /* Not unconditionally dead. */
2915 return 0;
2920 return 1;
2923 /* Called from splay_tree_delete for pbi->reg_cond_life. */
2925 static void
2926 free_reg_cond_life_info (splay_tree_value value)
2928 struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
2929 free (rcli);
2932 /* Helper function for flush_reg_cond_reg. */
2934 static int
2935 flush_reg_cond_reg_1 (splay_tree_node node, void *data)
2937 struct reg_cond_life_info *rcli;
2938 int *xdata = (int *) data;
2939 unsigned int regno = xdata[0];
2941 /* Don't need to search if last flushed value was farther on in
2942 the in-order traversal. */
2943 if (xdata[1] >= (int) node->key)
2944 return 0;
2946 /* Splice out portions of the expression that refer to regno. */
2947 rcli = (struct reg_cond_life_info *) node->value;
2948 rcli->condition = elim_reg_cond (rcli->condition, regno);
2949 if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
2950 rcli->stores = elim_reg_cond (rcli->stores, regno);
2952 /* If the entire condition is now false, signal the node to be removed. */
2953 if (rcli->condition == const0_rtx)
2955 xdata[1] = node->key;
2956 return -1;
2958 else if (rcli->condition == const1_rtx)
2959 abort ();
2961 return 0;
2964 /* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
2966 static void
2967 flush_reg_cond_reg (struct propagate_block_info *pbi, int regno)
2969 int pair[2];
2971 pair[0] = regno;
2972 pair[1] = -1;
2973 while (splay_tree_foreach (pbi->reg_cond_dead,
2974 flush_reg_cond_reg_1, pair) == -1)
2975 splay_tree_remove (pbi->reg_cond_dead, pair[1]);
2977 CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
2980 /* Logical arithmetic on predicate conditions. IOR, NOT and AND.
2981 For ior/and, the ADD flag determines whether we want to add the new
2982 condition X to the old one unconditionally. If it is zero, we will
2983 only return a new expression if X allows us to simplify part of
2984 OLD, otherwise we return NULL to the caller.
2985 If ADD is nonzero, we will return a new condition in all cases. The
2986 toplevel caller of one of these functions should always pass 1 for
2987 ADD. */
2989 static rtx
2990 ior_reg_cond (rtx old, rtx x, int add)
2992 rtx op0, op1;
2994 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
2996 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
2997 && REVERSE_CONDEXEC_PREDICATES_P (GET_CODE (x), GET_CODE (old))
2998 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
2999 return const1_rtx;
3000 if (GET_CODE (x) == GET_CODE (old)
3001 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3002 return old;
3003 if (! add)
3004 return NULL;
3005 return gen_rtx_IOR (0, old, x);
3008 switch (GET_CODE (old))
3010 case IOR:
3011 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3012 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3013 if (op0 != NULL || op1 != NULL)
3015 if (op0 == const0_rtx)
3016 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3017 if (op1 == const0_rtx)
3018 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3019 if (op0 == const1_rtx || op1 == const1_rtx)
3020 return const1_rtx;
3021 if (op0 == NULL)
3022 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3023 else if (rtx_equal_p (x, op0))
3024 /* (x | A) | x ~ (x | A). */
3025 return old;
3026 if (op1 == NULL)
3027 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3028 else if (rtx_equal_p (x, op1))
3029 /* (A | x) | x ~ (A | x). */
3030 return old;
3031 return gen_rtx_IOR (0, op0, op1);
3033 if (! add)
3034 return NULL;
3035 return gen_rtx_IOR (0, old, x);
3037 case AND:
3038 op0 = ior_reg_cond (XEXP (old, 0), x, 0);
3039 op1 = ior_reg_cond (XEXP (old, 1), x, 0);
3040 if (op0 != NULL || op1 != NULL)
3042 if (op0 == const1_rtx)
3043 return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
3044 if (op1 == const1_rtx)
3045 return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
3046 if (op0 == const0_rtx || op1 == const0_rtx)
3047 return const0_rtx;
3048 if (op0 == NULL)
3049 op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
3050 else if (rtx_equal_p (x, op0))
3051 /* (x & A) | x ~ x. */
3052 return op0;
3053 if (op1 == NULL)
3054 op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
3055 else if (rtx_equal_p (x, op1))
3056 /* (A & x) | x ~ x. */
3057 return op1;
3058 return gen_rtx_AND (0, op0, op1);
3060 if (! add)
3061 return NULL;
3062 return gen_rtx_IOR (0, old, x);
3064 case NOT:
3065 op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3066 if (op0 != NULL)
3067 return not_reg_cond (op0);
3068 if (! add)
3069 return NULL;
3070 return gen_rtx_IOR (0, old, x);
3072 default:
3073 abort ();
3077 static rtx
3078 not_reg_cond (rtx x)
3080 enum rtx_code x_code;
3082 if (x == const0_rtx)
3083 return const1_rtx;
3084 else if (x == const1_rtx)
3085 return const0_rtx;
3086 x_code = GET_CODE (x);
3087 if (x_code == NOT)
3088 return XEXP (x, 0);
3089 if (GET_RTX_CLASS (x_code) == '<'
3090 && GET_CODE (XEXP (x, 0)) == REG)
3092 if (XEXP (x, 1) != const0_rtx)
3093 abort ();
3095 return gen_rtx_fmt_ee (reverse_condition (x_code),
3096 VOIDmode, XEXP (x, 0), const0_rtx);
3098 return gen_rtx_NOT (0, x);
3101 static rtx
3102 and_reg_cond (rtx old, rtx x, int add)
3104 rtx op0, op1;
3106 if (GET_RTX_CLASS (GET_CODE (old)) == '<')
3108 if (GET_RTX_CLASS (GET_CODE (x)) == '<'
3109 && GET_CODE (x) == reverse_condition (GET_CODE (old))
3110 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3111 return const0_rtx;
3112 if (GET_CODE (x) == GET_CODE (old)
3113 && REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
3114 return old;
3115 if (! add)
3116 return NULL;
3117 return gen_rtx_AND (0, old, x);
3120 switch (GET_CODE (old))
3122 case IOR:
3123 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3124 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3125 if (op0 != NULL || op1 != NULL)
3127 if (op0 == const0_rtx)
3128 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3129 if (op1 == const0_rtx)
3130 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3131 if (op0 == const1_rtx || op1 == const1_rtx)
3132 return const1_rtx;
3133 if (op0 == NULL)
3134 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3135 else if (rtx_equal_p (x, op0))
3136 /* (x | A) & x ~ x. */
3137 return op0;
3138 if (op1 == NULL)
3139 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3140 else if (rtx_equal_p (x, op1))
3141 /* (A | x) & x ~ x. */
3142 return op1;
3143 return gen_rtx_IOR (0, op0, op1);
3145 if (! add)
3146 return NULL;
3147 return gen_rtx_AND (0, old, x);
3149 case AND:
3150 op0 = and_reg_cond (XEXP (old, 0), x, 0);
3151 op1 = and_reg_cond (XEXP (old, 1), x, 0);
3152 if (op0 != NULL || op1 != NULL)
3154 if (op0 == const1_rtx)
3155 return op1 ? op1 : gen_rtx_AND (0, XEXP (old, 1), x);
3156 if (op1 == const1_rtx)
3157 return op0 ? op0 : gen_rtx_AND (0, XEXP (old, 0), x);
3158 if (op0 == const0_rtx || op1 == const0_rtx)
3159 return const0_rtx;
3160 if (op0 == NULL)
3161 op0 = gen_rtx_AND (0, XEXP (old, 0), x);
3162 else if (rtx_equal_p (x, op0))
3163 /* (x & A) & x ~ (x & A). */
3164 return old;
3165 if (op1 == NULL)
3166 op1 = gen_rtx_AND (0, XEXP (old, 1), x);
3167 else if (rtx_equal_p (x, op1))
3168 /* (A & x) & x ~ (A & x). */
3169 return old;
3170 return gen_rtx_AND (0, op0, op1);
3172 if (! add)
3173 return NULL;
3174 return gen_rtx_AND (0, old, x);
3176 case NOT:
3177 op0 = ior_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
3178 if (op0 != NULL)
3179 return not_reg_cond (op0);
3180 if (! add)
3181 return NULL;
3182 return gen_rtx_AND (0, old, x);
3184 default:
3185 abort ();
3189 /* Given a condition X, remove references to reg REGNO and return the
3190 new condition. The removal will be done so that all conditions
3191 involving REGNO are considered to evaluate to false. This function
3192 is used when the value of REGNO changes. */
3194 static rtx
3195 elim_reg_cond (rtx x, unsigned int regno)
3197 rtx op0, op1;
3199 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
3201 if (REGNO (XEXP (x, 0)) == regno)
3202 return const0_rtx;
3203 return x;
3206 switch (GET_CODE (x))
3208 case AND:
3209 op0 = elim_reg_cond (XEXP (x, 0), regno);
3210 op1 = elim_reg_cond (XEXP (x, 1), regno);
3211 if (op0 == const0_rtx || op1 == const0_rtx)
3212 return const0_rtx;
3213 if (op0 == const1_rtx)
3214 return op1;
3215 if (op1 == const1_rtx)
3216 return op0;
3217 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3218 return x;
3219 return gen_rtx_AND (0, op0, op1);
3221 case IOR:
3222 op0 = elim_reg_cond (XEXP (x, 0), regno);
3223 op1 = elim_reg_cond (XEXP (x, 1), regno);
3224 if (op0 == const1_rtx || op1 == const1_rtx)
3225 return const1_rtx;
3226 if (op0 == const0_rtx)
3227 return op1;
3228 if (op1 == const0_rtx)
3229 return op0;
3230 if (op0 == XEXP (x, 0) && op1 == XEXP (x, 1))
3231 return x;
3232 return gen_rtx_IOR (0, op0, op1);
3234 case NOT:
3235 op0 = elim_reg_cond (XEXP (x, 0), regno);
3236 if (op0 == const0_rtx)
3237 return const1_rtx;
3238 if (op0 == const1_rtx)
3239 return const0_rtx;
3240 if (op0 != XEXP (x, 0))
3241 return not_reg_cond (op0);
3242 return x;
3244 default:
3245 abort ();
3248 #endif /* HAVE_conditional_execution */
3250 #ifdef AUTO_INC_DEC
3252 /* Try to substitute the auto-inc expression INC as the address inside
3253 MEM which occurs in INSN. Currently, the address of MEM is an expression
3254 involving INCR_REG, and INCR is the next use of INCR_REG; it is an insn
3255 that has a single set whose source is a PLUS of INCR_REG and something
3256 else. */
3258 static void
3259 attempt_auto_inc (struct propagate_block_info *pbi, rtx inc, rtx insn,
3260 rtx mem, rtx incr, rtx incr_reg)
3262 int regno = REGNO (incr_reg);
3263 rtx set = single_set (incr);
3264 rtx q = SET_DEST (set);
3265 rtx y = SET_SRC (set);
3266 int opnum = XEXP (y, 0) == incr_reg ? 0 : 1;
3268 /* Make sure this reg appears only once in this insn. */
3269 if (count_occurrences (PATTERN (insn), incr_reg, 1) != 1)
3270 return;
3272 if (dead_or_set_p (incr, incr_reg)
3273 /* Mustn't autoinc an eliminable register. */
3274 && (regno >= FIRST_PSEUDO_REGISTER
3275 || ! TEST_HARD_REG_BIT (elim_reg_set, regno)))
3277 /* This is the simple case. Try to make the auto-inc. If
3278 we can't, we are done. Otherwise, we will do any
3279 needed updates below. */
3280 if (! validate_change (insn, &XEXP (mem, 0), inc, 0))
3281 return;
3283 else if (GET_CODE (q) == REG
3284 /* PREV_INSN used here to check the semi-open interval
3285 [insn,incr). */
3286 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
3287 /* We must also check for sets of q as q may be
3288 a call clobbered hard register and there may
3289 be a call between PREV_INSN (insn) and incr. */
3290 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
3292 /* We have *p followed sometime later by q = p+size.
3293 Both p and q must be live afterward,
3294 and q is not used between INSN and its assignment.
3295 Change it to q = p, ...*q..., q = q+size.
3296 Then fall into the usual case. */
3297 rtx insns, temp;
3299 start_sequence ();
3300 emit_move_insn (q, incr_reg);
3301 insns = get_insns ();
3302 end_sequence ();
3304 /* If we can't make the auto-inc, or can't make the
3305 replacement into Y, exit. There's no point in making
3306 the change below if we can't do the auto-inc and doing
3307 so is not correct in the pre-inc case. */
3309 XEXP (inc, 0) = q;
3310 validate_change (insn, &XEXP (mem, 0), inc, 1);
3311 validate_change (incr, &XEXP (y, opnum), q, 1);
3312 if (! apply_change_group ())
3313 return;
3315 /* We now know we'll be doing this change, so emit the
3316 new insn(s) and do the updates. */
3317 emit_insn_before (insns, insn);
3319 if (pbi->bb->head == insn)
3320 pbi->bb->head = insns;
3322 /* INCR will become a NOTE and INSN won't contain a
3323 use of INCR_REG. If a use of INCR_REG was just placed in
3324 the insn before INSN, make that the next use.
3325 Otherwise, invalidate it. */
3326 if (GET_CODE (PREV_INSN (insn)) == INSN
3327 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
3328 && SET_SRC (PATTERN (PREV_INSN (insn))) == incr_reg)
3329 pbi->reg_next_use[regno] = PREV_INSN (insn);
3330 else
3331 pbi->reg_next_use[regno] = 0;
3333 incr_reg = q;
3334 regno = REGNO (q);
3336 /* REGNO is now used in INCR which is below INSN, but
3337 it previously wasn't live here. If we don't mark
3338 it as live, we'll put a REG_DEAD note for it
3339 on this insn, which is incorrect. */
3340 SET_REGNO_REG_SET (pbi->reg_live, regno);
3342 /* If there are any calls between INSN and INCR, show
3343 that REGNO now crosses them. */
3344 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
3345 if (GET_CODE (temp) == CALL_INSN)
3346 REG_N_CALLS_CROSSED (regno)++;
3348 /* Invalidate alias info for Q since we just changed its value. */
3349 clear_reg_alias_info (q);
3351 else
3352 return;
3354 /* If we haven't returned, it means we were able to make the
3355 auto-inc, so update the status. First, record that this insn
3356 has an implicit side effect. */
3358 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, incr_reg, REG_NOTES (insn));
3360 /* Modify the old increment-insn to simply copy
3361 the already-incremented value of our register. */
3362 if (! validate_change (incr, &SET_SRC (set), incr_reg, 0))
3363 abort ();
3365 /* If that makes it a no-op (copying the register into itself) delete
3366 it so it won't appear to be a "use" and a "set" of this
3367 register. */
3368 if (REGNO (SET_DEST (set)) == REGNO (incr_reg))
3370 /* If the original source was dead, it's dead now. */
3371 rtx note;
3373 while ((note = find_reg_note (incr, REG_DEAD, NULL_RTX)) != NULL_RTX)
3375 remove_note (incr, note);
3376 if (XEXP (note, 0) != incr_reg)
3377 CLEAR_REGNO_REG_SET (pbi->reg_live, REGNO (XEXP (note, 0)));
3380 PUT_CODE (incr, NOTE);
3381 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
3382 NOTE_SOURCE_FILE (incr) = 0;
3385 if (regno >= FIRST_PSEUDO_REGISTER)
3387 /* Count an extra reference to the reg. When a reg is
3388 incremented, spilling it is worse, so we want to make
3389 that less likely. */
3390 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3392 /* Count the increment as a setting of the register,
3393 even though it isn't a SET in rtl. */
3394 REG_N_SETS (regno)++;
3398 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
3399 reference. */
3401 static void
3402 find_auto_inc (struct propagate_block_info *pbi, rtx x, rtx insn)
3404 rtx addr = XEXP (x, 0);
3405 HOST_WIDE_INT offset = 0;
3406 rtx set, y, incr, inc_val;
3407 int regno;
3408 int size = GET_MODE_SIZE (GET_MODE (x));
3410 if (GET_CODE (insn) == JUMP_INSN)
3411 return;
3413 /* Here we detect use of an index register which might be good for
3414 postincrement, postdecrement, preincrement, or predecrement. */
3416 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
3417 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
3419 if (GET_CODE (addr) != REG)
3420 return;
3422 regno = REGNO (addr);
3424 /* Is the next use an increment that might make auto-increment? */
3425 incr = pbi->reg_next_use[regno];
3426 if (incr == 0 || BLOCK_NUM (incr) != BLOCK_NUM (insn))
3427 return;
3428 set = single_set (incr);
3429 if (set == 0 || GET_CODE (set) != SET)
3430 return;
3431 y = SET_SRC (set);
3433 if (GET_CODE (y) != PLUS)
3434 return;
3436 if (REG_P (XEXP (y, 0)) && REGNO (XEXP (y, 0)) == REGNO (addr))
3437 inc_val = XEXP (y, 1);
3438 else if (REG_P (XEXP (y, 1)) && REGNO (XEXP (y, 1)) == REGNO (addr))
3439 inc_val = XEXP (y, 0);
3440 else
3441 return;
3443 if (GET_CODE (inc_val) == CONST_INT)
3445 if (HAVE_POST_INCREMENT
3446 && (INTVAL (inc_val) == size && offset == 0))
3447 attempt_auto_inc (pbi, gen_rtx_POST_INC (Pmode, addr), insn, x,
3448 incr, addr);
3449 else if (HAVE_POST_DECREMENT
3450 && (INTVAL (inc_val) == -size && offset == 0))
3451 attempt_auto_inc (pbi, gen_rtx_POST_DEC (Pmode, addr), insn, x,
3452 incr, addr);
3453 else if (HAVE_PRE_INCREMENT
3454 && (INTVAL (inc_val) == size && offset == size))
3455 attempt_auto_inc (pbi, gen_rtx_PRE_INC (Pmode, addr), insn, x,
3456 incr, addr);
3457 else if (HAVE_PRE_DECREMENT
3458 && (INTVAL (inc_val) == -size && offset == -size))
3459 attempt_auto_inc (pbi, gen_rtx_PRE_DEC (Pmode, addr), insn, x,
3460 incr, addr);
3461 else if (HAVE_POST_MODIFY_DISP && offset == 0)
3462 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3463 gen_rtx_PLUS (Pmode,
3464 addr,
3465 inc_val)),
3466 insn, x, incr, addr);
3467 else if (HAVE_PRE_MODIFY_DISP && offset == INTVAL (inc_val))
3468 attempt_auto_inc (pbi, gen_rtx_PRE_MODIFY (Pmode, addr,
3469 gen_rtx_PLUS (Pmode,
3470 addr,
3471 inc_val)),
3472 insn, x, incr, addr);
3474 else if (GET_CODE (inc_val) == REG
3475 && ! reg_set_between_p (inc_val, PREV_INSN (insn),
3476 NEXT_INSN (incr)))
3479 if (HAVE_POST_MODIFY_REG && offset == 0)
3480 attempt_auto_inc (pbi, gen_rtx_POST_MODIFY (Pmode, addr,
3481 gen_rtx_PLUS (Pmode,
3482 addr,
3483 inc_val)),
3484 insn, x, incr, addr);
3488 #endif /* AUTO_INC_DEC */
3490 static void
3491 mark_used_reg (struct propagate_block_info *pbi, rtx reg,
3492 rtx cond ATTRIBUTE_UNUSED, rtx insn)
3494 unsigned int regno_first, regno_last, i;
3495 int some_was_live, some_was_dead, some_not_set;
3497 regno_last = regno_first = REGNO (reg);
3498 if (regno_first < FIRST_PSEUDO_REGISTER)
3499 regno_last += HARD_REGNO_NREGS (regno_first, GET_MODE (reg)) - 1;
3501 /* Find out if any of this register is live after this instruction. */
3502 some_was_live = some_was_dead = 0;
3503 for (i = regno_first; i <= regno_last; ++i)
3505 int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
3506 some_was_live |= needed_regno;
3507 some_was_dead |= ! needed_regno;
3510 /* Find out if any of the register was set this insn. */
3511 some_not_set = 0;
3512 for (i = regno_first; i <= regno_last; ++i)
3513 some_not_set |= ! REGNO_REG_SET_P (pbi->new_set, i);
3515 if (pbi->flags & (PROP_LOG_LINKS | PROP_AUTOINC))
3517 /* Record where each reg is used, so when the reg is set we know
3518 the next insn that uses it. */
3519 pbi->reg_next_use[regno_first] = insn;
3522 if (pbi->flags & PROP_REG_INFO)
3524 if (regno_first < FIRST_PSEUDO_REGISTER)
3526 /* If this is a register we are going to try to eliminate,
3527 don't mark it live here. If we are successful in
3528 eliminating it, it need not be live unless it is used for
3529 pseudos, in which case it will have been set live when it
3530 was allocated to the pseudos. If the register will not
3531 be eliminated, reload will set it live at that point.
3533 Otherwise, record that this function uses this register. */
3534 /* ??? The PPC backend tries to "eliminate" on the pic
3535 register to itself. This should be fixed. In the mean
3536 time, hack around it. */
3538 if (! (TEST_HARD_REG_BIT (elim_reg_set, regno_first)
3539 && (regno_first == FRAME_POINTER_REGNUM
3540 || regno_first == ARG_POINTER_REGNUM)))
3541 for (i = regno_first; i <= regno_last; ++i)
3542 regs_ever_live[i] = 1;
3544 else
3546 /* Keep track of which basic block each reg appears in. */
3548 int blocknum = pbi->bb->index;
3549 if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
3550 REG_BASIC_BLOCK (regno_first) = blocknum;
3551 else if (REG_BASIC_BLOCK (regno_first) != blocknum)
3552 REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
3554 /* Count (weighted) number of uses of each reg. */
3555 REG_FREQ (regno_first) += REG_FREQ_FROM_BB (pbi->bb);
3556 REG_N_REFS (regno_first)++;
3560 /* Record and count the insns in which a reg dies. If it is used in
3561 this insn and was dead below the insn then it dies in this insn.
3562 If it was set in this insn, we do not make a REG_DEAD note;
3563 likewise if we already made such a note. */
3564 if ((pbi->flags & (PROP_DEATH_NOTES | PROP_REG_INFO))
3565 && some_was_dead
3566 && some_not_set)
3568 /* Check for the case where the register dying partially
3569 overlaps the register set by this insn. */
3570 if (regno_first != regno_last)
3571 for (i = regno_first; i <= regno_last; ++i)
3572 some_was_live |= REGNO_REG_SET_P (pbi->new_set, i);
3574 /* If none of the words in X is needed, make a REG_DEAD note.
3575 Otherwise, we must make partial REG_DEAD notes. */
3576 if (! some_was_live)
3578 if ((pbi->flags & PROP_DEATH_NOTES)
3579 && ! find_regno_note (insn, REG_DEAD, regno_first))
3580 REG_NOTES (insn)
3581 = alloc_EXPR_LIST (REG_DEAD, reg, REG_NOTES (insn));
3583 if (pbi->flags & PROP_REG_INFO)
3584 REG_N_DEATHS (regno_first)++;
3586 else
3588 /* Don't make a REG_DEAD note for a part of a register
3589 that is set in the insn. */
3590 for (i = regno_first; i <= regno_last; ++i)
3591 if (! REGNO_REG_SET_P (pbi->reg_live, i)
3592 && ! dead_or_set_regno_p (insn, i))
3593 REG_NOTES (insn)
3594 = alloc_EXPR_LIST (REG_DEAD,
3595 regno_reg_rtx[i],
3596 REG_NOTES (insn));
3600 /* Mark the register as being live. */
3601 for (i = regno_first; i <= regno_last; ++i)
3603 #ifdef HAVE_conditional_execution
3604 int this_was_live = REGNO_REG_SET_P (pbi->reg_live, i);
3605 #endif
3607 SET_REGNO_REG_SET (pbi->reg_live, i);
3609 #ifdef HAVE_conditional_execution
3610 /* If this is a conditional use, record that fact. If it is later
3611 conditionally set, we'll know to kill the register. */
3612 if (cond != NULL_RTX)
3614 splay_tree_node node;
3615 struct reg_cond_life_info *rcli;
3616 rtx ncond;
3618 if (this_was_live)
3620 node = splay_tree_lookup (pbi->reg_cond_dead, i);
3621 if (node == NULL)
3623 /* The register was unconditionally live previously.
3624 No need to do anything. */
3626 else
3628 /* The register was conditionally live previously.
3629 Subtract the new life cond from the old death cond. */
3630 rcli = (struct reg_cond_life_info *) node->value;
3631 ncond = rcli->condition;
3632 ncond = and_reg_cond (ncond, not_reg_cond (cond), 1);
3634 /* If the register is now unconditionally live,
3635 remove the entry in the splay_tree. */
3636 if (ncond == const0_rtx)
3637 splay_tree_remove (pbi->reg_cond_dead, i);
3638 else
3640 rcli->condition = ncond;
3641 SET_REGNO_REG_SET (pbi->reg_cond_reg,
3642 REGNO (XEXP (cond, 0)));
3646 else
3648 /* The register was not previously live at all. Record
3649 the condition under which it is still dead. */
3650 rcli = xmalloc (sizeof (*rcli));
3651 rcli->condition = not_reg_cond (cond);
3652 rcli->stores = const0_rtx;
3653 rcli->orig_condition = const0_rtx;
3654 splay_tree_insert (pbi->reg_cond_dead, i,
3655 (splay_tree_value) rcli);
3657 SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
3660 else if (this_was_live)
3662 /* The register may have been conditionally live previously, but
3663 is now unconditionally live. Remove it from the conditionally
3664 dead list, so that a conditional set won't cause us to think
3665 it dead. */
3666 splay_tree_remove (pbi->reg_cond_dead, i);
3668 #endif
3672 /* Scan expression X and store a 1-bit in NEW_LIVE for each reg it uses.
3673 This is done assuming the registers needed from X are those that
3674 have 1-bits in PBI->REG_LIVE.
3676 INSN is the containing instruction. If INSN is dead, this function
3677 is not called. */
3679 static void
3680 mark_used_regs (struct propagate_block_info *pbi, rtx x, rtx cond, rtx insn)
3682 RTX_CODE code;
3683 int regno;
3684 int flags = pbi->flags;
3686 retry:
3687 if (!x)
3688 return;
3689 code = GET_CODE (x);
3690 switch (code)
3692 case LABEL_REF:
3693 case SYMBOL_REF:
3694 case CONST_INT:
3695 case CONST:
3696 case CONST_DOUBLE:
3697 case CONST_VECTOR:
3698 case PC:
3699 case ADDR_VEC:
3700 case ADDR_DIFF_VEC:
3701 return;
3703 #ifdef HAVE_cc0
3704 case CC0:
3705 pbi->cc0_live = 1;
3706 return;
3707 #endif
3709 case CLOBBER:
3710 /* If we are clobbering a MEM, mark any registers inside the address
3711 as being used. */
3712 if (GET_CODE (XEXP (x, 0)) == MEM)
3713 mark_used_regs (pbi, XEXP (XEXP (x, 0), 0), cond, insn);
3714 return;
3716 case MEM:
3717 /* Don't bother watching stores to mems if this is not the
3718 final pass. We'll not be deleting dead stores this round. */
3719 if (optimize && (flags & PROP_SCAN_DEAD_STORES))
3721 /* Invalidate the data for the last MEM stored, but only if MEM is
3722 something that can be stored into. */
3723 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
3724 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
3725 /* Needn't clear the memory set list. */
3727 else
3729 rtx temp = pbi->mem_set_list;
3730 rtx prev = NULL_RTX;
3731 rtx next;
3733 while (temp)
3735 next = XEXP (temp, 1);
3736 if (unchanging_anti_dependence (XEXP (temp, 0), x))
3738 /* Splice temp out of the list. */
3739 if (prev)
3740 XEXP (prev, 1) = next;
3741 else
3742 pbi->mem_set_list = next;
3743 free_EXPR_LIST_node (temp);
3744 pbi->mem_set_list_len--;
3746 else
3747 prev = temp;
3748 temp = next;
3752 /* If the memory reference had embedded side effects (autoincrement
3753 address modes. Then we may need to kill some entries on the
3754 memory set list. */
3755 if (insn)
3756 for_each_rtx (&PATTERN (insn), invalidate_mems_from_autoinc, pbi);
3759 #ifdef AUTO_INC_DEC
3760 if (flags & PROP_AUTOINC)
3761 find_auto_inc (pbi, x, insn);
3762 #endif
3763 break;
3765 case SUBREG:
3766 #ifdef CANNOT_CHANGE_MODE_CLASS
3767 if ((flags & PROP_REG_INFO)
3768 && GET_CODE (SUBREG_REG (x)) == REG
3769 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER)
3770 bitmap_set_bit (&subregs_of_mode, REGNO (SUBREG_REG (x))
3771 * MAX_MACHINE_MODE
3772 + GET_MODE (x));
3773 #endif
3775 /* While we're here, optimize this case. */
3776 x = SUBREG_REG (x);
3777 if (GET_CODE (x) != REG)
3778 goto retry;
3779 /* Fall through. */
3781 case REG:
3782 /* See a register other than being set => mark it as needed. */
3783 mark_used_reg (pbi, x, cond, insn);
3784 return;
3786 case SET:
3788 rtx testreg = SET_DEST (x);
3789 int mark_dest = 0;
3791 /* If storing into MEM, don't show it as being used. But do
3792 show the address as being used. */
3793 if (GET_CODE (testreg) == MEM)
3795 #ifdef AUTO_INC_DEC
3796 if (flags & PROP_AUTOINC)
3797 find_auto_inc (pbi, testreg, insn);
3798 #endif
3799 mark_used_regs (pbi, XEXP (testreg, 0), cond, insn);
3800 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3801 return;
3804 /* Storing in STRICT_LOW_PART is like storing in a reg
3805 in that this SET might be dead, so ignore it in TESTREG.
3806 but in some other ways it is like using the reg.
3808 Storing in a SUBREG or a bit field is like storing the entire
3809 register in that if the register's value is not used
3810 then this SET is not needed. */
3811 while (GET_CODE (testreg) == STRICT_LOW_PART
3812 || GET_CODE (testreg) == ZERO_EXTRACT
3813 || GET_CODE (testreg) == SIGN_EXTRACT
3814 || GET_CODE (testreg) == SUBREG)
3816 #ifdef CANNOT_CHANGE_MODE_CLASS
3817 if ((flags & PROP_REG_INFO)
3818 && GET_CODE (testreg) == SUBREG
3819 && GET_CODE (SUBREG_REG (testreg)) == REG
3820 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER)
3821 bitmap_set_bit (&subregs_of_mode, REGNO (SUBREG_REG (testreg))
3822 * MAX_MACHINE_MODE
3823 + GET_MODE (testreg));
3824 #endif
3826 /* Modifying a single register in an alternate mode
3827 does not use any of the old value. But these other
3828 ways of storing in a register do use the old value. */
3829 if (GET_CODE (testreg) == SUBREG
3830 && !((REG_BYTES (SUBREG_REG (testreg))
3831 + UNITS_PER_WORD - 1) / UNITS_PER_WORD
3832 > (REG_BYTES (testreg)
3833 + UNITS_PER_WORD - 1) / UNITS_PER_WORD))
3835 else
3836 mark_dest = 1;
3838 testreg = XEXP (testreg, 0);
3841 /* If this is a store into a register or group of registers,
3842 recursively scan the value being stored. */
3844 if ((GET_CODE (testreg) == PARALLEL
3845 && GET_MODE (testreg) == BLKmode)
3846 || (GET_CODE (testreg) == REG
3847 && (regno = REGNO (testreg),
3848 ! (regno == FRAME_POINTER_REGNUM
3849 && (! reload_completed || frame_pointer_needed)))
3850 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
3851 && ! (regno == HARD_FRAME_POINTER_REGNUM
3852 && (! reload_completed || frame_pointer_needed))
3853 #endif
3854 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
3855 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
3856 #endif
3859 if (mark_dest)
3860 mark_used_regs (pbi, SET_DEST (x), cond, insn);
3861 mark_used_regs (pbi, SET_SRC (x), cond, insn);
3862 return;
3865 break;
3867 case ASM_OPERANDS:
3868 case UNSPEC_VOLATILE:
3869 case TRAP_IF:
3870 case ASM_INPUT:
3872 /* Traditional and volatile asm instructions must be considered to use
3873 and clobber all hard registers, all pseudo-registers and all of
3874 memory. So must TRAP_IF and UNSPEC_VOLATILE operations.
3876 Consider for instance a volatile asm that changes the fpu rounding
3877 mode. An insn should not be moved across this even if it only uses
3878 pseudo-regs because it might give an incorrectly rounded result.
3880 ?!? Unfortunately, marking all hard registers as live causes massive
3881 problems for the register allocator and marking all pseudos as live
3882 creates mountains of uninitialized variable warnings.
3884 So for now, just clear the memory set list and mark any regs
3885 we can find in ASM_OPERANDS as used. */
3886 if (code != ASM_OPERANDS || MEM_VOLATILE_P (x))
3888 free_EXPR_LIST_list (&pbi->mem_set_list);
3889 pbi->mem_set_list_len = 0;
3892 /* For all ASM_OPERANDS, we must traverse the vector of input operands.
3893 We can not just fall through here since then we would be confused
3894 by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate
3895 traditional asms unlike their normal usage. */
3896 if (code == ASM_OPERANDS)
3898 int j;
3900 for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++)
3901 mark_used_regs (pbi, ASM_OPERANDS_INPUT (x, j), cond, insn);
3903 break;
3906 case COND_EXEC:
3907 if (cond != NULL_RTX)
3908 abort ();
3910 mark_used_regs (pbi, COND_EXEC_TEST (x), NULL_RTX, insn);
3912 cond = COND_EXEC_TEST (x);
3913 x = COND_EXEC_CODE (x);
3914 goto retry;
3916 default:
3917 break;
3920 /* Recursively scan the operands of this expression. */
3923 const char * const fmt = GET_RTX_FORMAT (code);
3924 int i;
3926 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3928 if (fmt[i] == 'e')
3930 /* Tail recursive case: save a function call level. */
3931 if (i == 0)
3933 x = XEXP (x, 0);
3934 goto retry;
3936 mark_used_regs (pbi, XEXP (x, i), cond, insn);
3938 else if (fmt[i] == 'E')
3940 int j;
3941 for (j = 0; j < XVECLEN (x, i); j++)
3942 mark_used_regs (pbi, XVECEXP (x, i, j), cond, insn);
3948 #ifdef AUTO_INC_DEC
3950 static int
3951 try_pre_increment_1 (struct propagate_block_info *pbi, rtx insn)
3953 /* Find the next use of this reg. If in same basic block,
3954 make it do pre-increment or pre-decrement if appropriate. */
3955 rtx x = single_set (insn);
3956 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
3957 * INTVAL (XEXP (SET_SRC (x), 1)));
3958 int regno = REGNO (SET_DEST (x));
3959 rtx y = pbi->reg_next_use[regno];
3960 if (y != 0
3961 && SET_DEST (x) != stack_pointer_rtx
3962 && BLOCK_NUM (y) == BLOCK_NUM (insn)
3963 /* Don't do this if the reg dies, or gets set in y; a standard addressing
3964 mode would be better. */
3965 && ! dead_or_set_p (y, SET_DEST (x))
3966 && try_pre_increment (y, SET_DEST (x), amount))
3968 /* We have found a suitable auto-increment and already changed
3969 insn Y to do it. So flush this increment instruction. */
3970 propagate_block_delete_insn (insn);
3972 /* Count a reference to this reg for the increment insn we are
3973 deleting. When a reg is incremented, spilling it is worse,
3974 so we want to make that less likely. */
3975 if (regno >= FIRST_PSEUDO_REGISTER)
3977 REG_FREQ (regno) += REG_FREQ_FROM_BB (pbi->bb);
3978 REG_N_SETS (regno)++;
3981 /* Flush any remembered memories depending on the value of
3982 the incremented register. */
3983 invalidate_mems_from_set (pbi, SET_DEST (x));
3985 return 1;
3987 return 0;
3990 /* Try to change INSN so that it does pre-increment or pre-decrement
3991 addressing on register REG in order to add AMOUNT to REG.
3992 AMOUNT is negative for pre-decrement.
3993 Returns 1 if the change could be made.
3994 This checks all about the validity of the result of modifying INSN. */
3996 static int
3997 try_pre_increment (rtx insn, rtx reg, HOST_WIDE_INT amount)
3999 rtx use;
4001 /* Nonzero if we can try to make a pre-increment or pre-decrement.
4002 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
4003 int pre_ok = 0;
4004 /* Nonzero if we can try to make a post-increment or post-decrement.
4005 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
4006 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
4007 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
4008 int post_ok = 0;
4010 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
4011 int do_post = 0;
4013 /* From the sign of increment, see which possibilities are conceivable
4014 on this target machine. */
4015 if (HAVE_PRE_INCREMENT && amount > 0)
4016 pre_ok = 1;
4017 if (HAVE_POST_INCREMENT && amount > 0)
4018 post_ok = 1;
4020 if (HAVE_PRE_DECREMENT && amount < 0)
4021 pre_ok = 1;
4022 if (HAVE_POST_DECREMENT && amount < 0)
4023 post_ok = 1;
4025 if (! (pre_ok || post_ok))
4026 return 0;
4028 /* It is not safe to add a side effect to a jump insn
4029 because if the incremented register is spilled and must be reloaded
4030 there would be no way to store the incremented value back in memory. */
4032 if (GET_CODE (insn) == JUMP_INSN)
4033 return 0;
4035 use = 0;
4036 if (pre_ok)
4037 use = find_use_as_address (PATTERN (insn), reg, 0);
4038 if (post_ok && (use == 0 || use == (rtx) (size_t) 1))
4040 use = find_use_as_address (PATTERN (insn), reg, -amount);
4041 do_post = 1;
4044 if (use == 0 || use == (rtx) (size_t) 1)
4045 return 0;
4047 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
4048 return 0;
4050 /* See if this combination of instruction and addressing mode exists. */
4051 if (! validate_change (insn, &XEXP (use, 0),
4052 gen_rtx_fmt_e (amount > 0
4053 ? (do_post ? POST_INC : PRE_INC)
4054 : (do_post ? POST_DEC : PRE_DEC),
4055 Pmode, reg), 0))
4056 return 0;
4058 /* Record that this insn now has an implicit side effect on X. */
4059 REG_NOTES (insn) = alloc_EXPR_LIST (REG_INC, reg, REG_NOTES (insn));
4060 return 1;
4063 #endif /* AUTO_INC_DEC */
4065 /* Find the place in the rtx X where REG is used as a memory address.
4066 Return the MEM rtx that so uses it.
4067 If PLUSCONST is nonzero, search instead for a memory address equivalent to
4068 (plus REG (const_int PLUSCONST)).
4070 If such an address does not appear, return 0.
4071 If REG appears more than once, or is used other than in such an address,
4072 return (rtx) 1. */
4075 find_use_as_address (rtx x, rtx reg, HOST_WIDE_INT plusconst)
4077 enum rtx_code code = GET_CODE (x);
4078 const char * const fmt = GET_RTX_FORMAT (code);
4079 int i;
4080 rtx value = 0;
4081 rtx tem;
4083 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
4084 return x;
4086 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
4087 && XEXP (XEXP (x, 0), 0) == reg
4088 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
4089 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
4090 return x;
4092 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
4094 /* If REG occurs inside a MEM used in a bit-field reference,
4095 that is unacceptable. */
4096 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
4097 return (rtx) (size_t) 1;
4100 if (x == reg)
4101 return (rtx) (size_t) 1;
4103 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4105 if (fmt[i] == 'e')
4107 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
4108 if (value == 0)
4109 value = tem;
4110 else if (tem != 0)
4111 return (rtx) (size_t) 1;
4113 else if (fmt[i] == 'E')
4115 int j;
4116 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4118 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
4119 if (value == 0)
4120 value = tem;
4121 else if (tem != 0)
4122 return (rtx) (size_t) 1;
4127 return value;
4130 /* Write information about registers and basic blocks into FILE.
4131 This is part of making a debugging dump. */
4133 void
4134 dump_regset (regset r, FILE *outf)
4136 int i;
4137 if (r == NULL)
4139 fputs (" (nil)", outf);
4140 return;
4143 EXECUTE_IF_SET_IN_REG_SET (r, 0, i,
4145 fprintf (outf, " %d", i);
4146 if (i < FIRST_PSEUDO_REGISTER)
4147 fprintf (outf, " [%s]",
4148 reg_names[i]);
4152 /* Print a human-readable representation of R on the standard error
4153 stream. This function is designed to be used from within the
4154 debugger. */
4156 void
4157 debug_regset (regset r)
4159 dump_regset (r, stderr);
4160 putc ('\n', stderr);
4163 /* Recompute register set/reference counts immediately prior to register
4164 allocation.
4166 This avoids problems with set/reference counts changing to/from values
4167 which have special meanings to the register allocators.
4169 Additionally, the reference counts are the primary component used by the
4170 register allocators to prioritize pseudos for allocation to hard regs.
4171 More accurate reference counts generally lead to better register allocation.
4173 F is the first insn to be scanned.
4175 LOOP_STEP denotes how much loop_depth should be incremented per
4176 loop nesting level in order to increase the ref count more for
4177 references in a loop.
4179 It might be worthwhile to update REG_LIVE_LENGTH, REG_BASIC_BLOCK and
4180 possibly other information which is used by the register allocators. */
4182 void
4183 recompute_reg_usage (rtx f ATTRIBUTE_UNUSED, int loop_step ATTRIBUTE_UNUSED)
4185 allocate_reg_life_data ();
4186 update_life_info (NULL, UPDATE_LIFE_LOCAL, PROP_REG_INFO);
4189 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from a set of
4190 blocks. If BLOCKS is NULL, assume the universal set. Returns a count
4191 of the number of registers that died. */
4194 count_or_remove_death_notes (sbitmap blocks, int kill)
4196 int count = 0;
4197 int i;
4198 basic_block bb;
4201 /* This used to be a loop over all the blocks with a membership test
4202 inside the loop. That can be amazingly expensive on a large CFG
4203 when only a small number of bits are set in BLOCKs (for example,
4204 the calls from the scheduler typically have very few bits set).
4206 For extra credit, someone should convert BLOCKS to a bitmap rather
4207 than an sbitmap. */
4208 if (blocks)
4210 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4212 count += count_or_remove_death_notes_bb (BASIC_BLOCK (i), kill);
4215 else
4217 FOR_EACH_BB (bb)
4219 count += count_or_remove_death_notes_bb (bb, kill);
4223 return count;
4226 /* Optionally removes all the REG_DEAD and REG_UNUSED notes from basic
4227 block BB. Returns a count of the number of registers that died. */
4229 static int
4230 count_or_remove_death_notes_bb (basic_block bb, int kill)
4232 int count = 0;
4233 rtx insn;
4235 for (insn = bb->head;; insn = NEXT_INSN (insn))
4237 if (INSN_P (insn))
4239 rtx *pprev = &REG_NOTES (insn);
4240 rtx link = *pprev;
4242 while (link)
4244 switch (REG_NOTE_KIND (link))
4246 case REG_DEAD:
4247 if (GET_CODE (XEXP (link, 0)) == REG)
4249 rtx reg = XEXP (link, 0);
4250 int n;
4252 if (REGNO (reg) >= FIRST_PSEUDO_REGISTER)
4253 n = 1;
4254 else
4255 n = HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg));
4256 count += n;
4259 /* Fall through. */
4261 case REG_UNUSED:
4262 if (kill)
4264 rtx next = XEXP (link, 1);
4265 free_EXPR_LIST_node (link);
4266 *pprev = link = next;
4267 break;
4269 /* Fall through. */
4271 default:
4272 pprev = &XEXP (link, 1);
4273 link = *pprev;
4274 break;
4279 if (insn == bb->end)
4280 break;
4283 return count;
4286 /* Clear LOG_LINKS fields of insns in a selected blocks or whole chain
4287 if blocks is NULL. */
4289 static void
4290 clear_log_links (sbitmap blocks)
4292 rtx insn;
4293 int i;
4295 if (!blocks)
4297 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4298 if (INSN_P (insn))
4299 free_INSN_LIST_list (&LOG_LINKS (insn));
4301 else
4302 EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
4304 basic_block bb = BASIC_BLOCK (i);
4306 for (insn = bb->head; insn != NEXT_INSN (bb->end);
4307 insn = NEXT_INSN (insn))
4308 if (INSN_P (insn))
4309 free_INSN_LIST_list (&LOG_LINKS (insn));
4313 /* Given a register bitmap, turn on the bits in a HARD_REG_SET that
4314 correspond to the hard registers, if any, set in that map. This
4315 could be done far more efficiently by having all sorts of special-cases
4316 with moving single words, but probably isn't worth the trouble. */
4318 void
4319 reg_set_to_hard_reg_set (HARD_REG_SET *to, bitmap from)
4321 int i;
4323 EXECUTE_IF_SET_IN_BITMAP
4324 (from, 0, i,
4326 if (i >= FIRST_PSEUDO_REGISTER)
4327 return;
4328 SET_HARD_REG_BIT (*to, i);