1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 88, 92-96, 1997 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
22 /* This file contains the data flow analysis pass of the compiler.
23 It computes data flow information
24 which tells combine_instructions which insns to consider combining
25 and controls register allocation.
27 Additional data flow information that is too bulky to record
28 is generated during the analysis, and is used at that time to
29 create autoincrement and autodecrement addressing.
31 The first step is dividing the function into basic blocks.
32 find_basic_blocks does this. Then life_analysis determines
33 where each register is live and where it is dead.
35 ** find_basic_blocks **
37 find_basic_blocks divides the current function's rtl
38 into basic blocks. It records the beginnings and ends of the
39 basic blocks in the vectors basic_block_head and basic_block_end,
40 and the number of blocks in n_basic_blocks.
42 find_basic_blocks also finds any unreachable loops
47 life_analysis is called immediately after find_basic_blocks.
48 It uses the basic block information to determine where each
49 hard or pseudo register is live.
51 ** live-register info **
53 The information about where each register is live is in two parts:
54 the REG_NOTES of insns, and the vector basic_block_live_at_start.
56 basic_block_live_at_start has an element for each basic block,
57 and the element is a bit-vector with a bit for each hard or pseudo
58 register. The bit is 1 if the register is live at the beginning
61 Two types of elements can be added to an insn's REG_NOTES.
62 A REG_DEAD note is added to an insn's REG_NOTES for any register
63 that meets both of two conditions: The value in the register is not
64 needed in subsequent insns and the insn does not replace the value in
65 the register (in the case of multi-word hard registers, the value in
66 each register must be replaced by the insn to avoid a REG_DEAD note).
68 In the vast majority of cases, an object in a REG_DEAD note will be
69 used somewhere in the insn. The (rare) exception to this is if an
70 insn uses a multi-word hard register and only some of the registers are
71 needed in subsequent insns. In that case, REG_DEAD notes will be
72 provided for those hard registers that are not subsequently needed.
73 Partial REG_DEAD notes of this type do not occur when an insn sets
74 only some of the hard registers used in such a multi-word operand;
75 omitting REG_DEAD notes for objects stored in an insn is optional and
76 the desire to do so does not justify the complexity of the partial
79 REG_UNUSED notes are added for each register that is set by the insn
80 but is unused subsequently (if every register set by the insn is unused
81 and the insn does not reference memory or have some other side-effect,
82 the insn is deleted instead). If only part of a multi-word hard
83 register is used in a subsequent insn, REG_UNUSED notes are made for
84 the parts that will not be used.
86 To determine which registers are live after any insn, one can
87 start from the beginning of the basic block and scan insns, noting
88 which registers are set by each insn and which die there.
90 ** Other actions of life_analysis **
92 life_analysis sets up the LOG_LINKS fields of insns because the
93 information needed to do so is readily available.
95 life_analysis deletes insns whose only effect is to store a value
98 life_analysis notices cases where a reference to a register as
99 a memory address can be combined with a preceding or following
100 incrementation or decrementation of the register. The separate
101 instruction to increment or decrement is deleted and the address
102 is changed to a POST_INC or similar rtx.
104 Each time an incrementing or decrementing address is created,
105 a REG_INC element is added to the insn's REG_NOTES list.
107 life_analysis fills in certain vectors containing information about
108 register usage: reg_n_refs, reg_n_deaths, reg_n_sets, reg_live_length,
109 reg_n_calls_crosses and reg_basic_block. */
114 #include "basic-block.h"
115 #include "insn-config.h"
117 #include "hard-reg-set.h"
123 #define obstack_chunk_alloc xmalloc
124 #define obstack_chunk_free free
126 /* The contents of the current function definition are allocated
127 in this obstack, and all are freed at the end of the function.
128 For top-level functions, this is temporary_obstack.
129 Separate obstacks are made for nested functions. */
131 extern struct obstack *function_obstack;
133 /* List of labels that must never be deleted. */
134 extern rtx forced_labels;
136 /* Get the basic block number of an insn.
137 This info should not be expected to remain available
138 after the end of life_analysis. */
140 /* This is the limit of the allocated space in the following two arrays. */
142 static int max_uid_for_flow;
144 #define BLOCK_NUM(INSN) uid_block_number[INSN_UID (INSN)]
146 /* This is where the BLOCK_NUM values are really stored.
147 This is set up by find_basic_blocks and used there and in life_analysis,
150 static int *uid_block_number;
152 /* INSN_VOLATILE (insn) is 1 if the insn refers to anything volatile. */
154 #define INSN_VOLATILE(INSN) uid_volatile[INSN_UID (INSN)]
155 static char *uid_volatile;
157 /* Number of basic blocks in the current function. */
161 /* Maximum register number used in this function, plus one. */
165 /* Maximum number of SCRATCH rtx's used in any basic block of this
170 /* Number of SCRATCH rtx's in the current block. */
172 static int num_scratch;
174 /* Indexed by n, giving various register information */
176 reg_info *reg_n_info;
178 /* Element N is the next insn that uses (hard or pseudo) register number N
179 within the current basic block; or zero, if there is no such insn.
180 This is valid only during the final backward scan in propagate_block. */
182 static rtx *reg_next_use;
184 /* Size of a regset for the current function,
185 in (1) bytes and (2) elements. */
190 /* Element N is first insn in basic block N.
191 This info lasts until we finish compiling the function. */
193 rtx *basic_block_head;
195 /* Element N is last insn in basic block N.
196 This info lasts until we finish compiling the function. */
198 rtx *basic_block_end;
200 /* Element N is a regset describing the registers live
201 at the start of basic block N.
202 This info lasts until we finish compiling the function. */
204 regset *basic_block_live_at_start;
206 /* Regset of regs live when calls to `setjmp'-like functions happen. */
208 regset regs_live_at_setjmp;
210 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
211 that have to go in the same hard reg.
212 The first two regs in the list are a pair, and the next two
213 are another pair, etc. */
216 /* Element N is nonzero if control can drop into basic block N
217 from the preceding basic block. Freed after life_analysis. */
219 static char *basic_block_drops_in;
221 /* Element N is depth within loops of the last insn in basic block number N.
222 Freed after life_analysis. */
224 static short *basic_block_loop_depth;
226 /* Element N nonzero if basic block N can actually be reached.
227 Vector exists only during find_basic_blocks. */
229 static char *block_live_static;
231 /* Depth within loops of basic block being scanned for lifetime analysis,
232 plus one. This is the weight attached to references to registers. */
234 static int loop_depth;
236 /* During propagate_block, this is non-zero if the value of CC0 is live. */
240 /* During propagate_block, this contains the last MEM stored into. It
241 is used to eliminate consecutive stores to the same location. */
243 static rtx last_mem_set;
245 /* Set of registers that may be eliminable. These are handled specially
246 in updating regs_ever_live. */
248 static HARD_REG_SET elim_reg_set;
250 /* Forward declarations */
251 static void find_basic_blocks PROTO((rtx, rtx));
252 static int jmp_uses_reg_or_mem PROTO((rtx));
253 static void mark_label_ref PROTO((rtx, rtx, int));
254 static void life_analysis PROTO((rtx, int));
255 void allocate_for_life_analysis PROTO((void));
256 static void init_regset_vector PROTO((regset *, int, int, struct obstack *));
257 static void propagate_block PROTO((regset, rtx, rtx, int,
259 static rtx flow_delete_insn PROTO((rtx));
260 static int insn_dead_p PROTO((rtx, regset, int));
261 static int libcall_dead_p PROTO((rtx, regset, rtx, rtx));
262 static void mark_set_regs PROTO((regset, regset, rtx,
264 static void mark_set_1 PROTO((regset, regset, rtx,
266 static void find_auto_inc PROTO((regset, rtx, rtx));
267 static void mark_used_regs PROTO((regset, regset, rtx, int, rtx));
268 static int try_pre_increment_1 PROTO((rtx));
269 static int try_pre_increment PROTO((rtx, rtx, HOST_WIDE_INT));
270 static rtx find_use_as_address PROTO((rtx, rtx, HOST_WIDE_INT));
271 void dump_flow_info PROTO((FILE *));
273 /* Find basic blocks of the current function and perform data flow analysis.
274 F is the first insn of the function and NREGS the number of register numbers
278 flow_analysis (f, nregs, file)
285 rtx nonlocal_label_list = nonlocal_label_rtx_list ();
287 #ifdef ELIMINABLE_REGS
288 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
291 /* Record which registers will be eliminated. We use this in
294 CLEAR_HARD_REG_SET (elim_reg_set);
296 #ifdef ELIMINABLE_REGS
297 for (i = 0; i < sizeof eliminables / sizeof eliminables[0]; i++)
298 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
300 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
303 /* Count the basic blocks. Also find maximum insn uid value used. */
306 register RTX_CODE prev_code = JUMP_INSN;
307 register RTX_CODE code;
309 max_uid_for_flow = 0;
311 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
313 code = GET_CODE (insn);
314 if (INSN_UID (insn) > max_uid_for_flow)
315 max_uid_for_flow = INSN_UID (insn);
316 if (code == CODE_LABEL
317 || (GET_RTX_CLASS (code) == 'i'
318 && (prev_code == JUMP_INSN
319 || (prev_code == CALL_INSN
320 && nonlocal_label_list != 0)
321 || prev_code == BARRIER)))
324 if (code == CALL_INSN && find_reg_note (insn, REG_RETVAL, NULL_RTX))
333 /* Leave space for insns we make in some cases for auto-inc. These cases
334 are rare, so we don't need too much space. */
335 max_uid_for_flow += max_uid_for_flow / 10;
338 /* Allocate some tables that last till end of compiling this function
339 and some needed only in find_basic_blocks and life_analysis. */
342 basic_block_head = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
343 basic_block_end = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
344 basic_block_drops_in = (char *) alloca (n_basic_blocks);
345 basic_block_loop_depth = (short *) alloca (n_basic_blocks * sizeof (short));
347 = (int *) alloca ((max_uid_for_flow + 1) * sizeof (int));
348 uid_volatile = (char *) alloca (max_uid_for_flow + 1);
349 bzero (uid_volatile, max_uid_for_flow + 1);
351 find_basic_blocks (f, nonlocal_label_list);
352 life_analysis (f, nregs);
354 dump_flow_info (file);
356 basic_block_drops_in = 0;
357 uid_block_number = 0;
358 basic_block_loop_depth = 0;
361 /* Find all basic blocks of the function whose first insn is F.
362 Store the correct data in the tables that describe the basic blocks,
363 set up the chains of references for each CODE_LABEL, and
364 delete any entire basic blocks that cannot be reached.
366 NONLOCAL_LABEL_LIST is the same local variable from flow_analysis. */
369 find_basic_blocks (f, nonlocal_label_list)
370 rtx f, nonlocal_label_list;
374 register char *block_live = (char *) alloca (n_basic_blocks);
375 register char *block_marked = (char *) alloca (n_basic_blocks);
376 /* List of label_refs to all labels whose addresses are taken
378 rtx label_value_list;
380 enum rtx_code prev_code, code;
386 label_value_list = 0;
387 block_live_static = block_live;
388 bzero (block_live, n_basic_blocks);
389 bzero (block_marked, n_basic_blocks);
391 /* Initialize with just block 0 reachable and no blocks marked. */
392 if (n_basic_blocks > 0)
395 /* Initialize the ref chain of each label to 0. Record where all the
396 blocks start and end and their depth in loops. For each insn, record
397 the block it is in. Also mark as reachable any blocks headed by labels
398 that must not be deleted. */
400 for (insn = f, i = -1, prev_code = JUMP_INSN, depth = 1;
401 insn; insn = NEXT_INSN (insn))
403 code = GET_CODE (insn);
406 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
408 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
412 /* A basic block starts at label, or after something that can jump. */
413 else if (code == CODE_LABEL
414 || (GET_RTX_CLASS (code) == 'i'
415 && (prev_code == JUMP_INSN
416 || (prev_code == CALL_INSN
417 && nonlocal_label_list != 0
418 && ! find_reg_note (insn, REG_RETVAL, NULL_RTX))
419 || prev_code == BARRIER)))
421 basic_block_head[++i] = insn;
422 basic_block_end[i] = insn;
423 basic_block_loop_depth[i] = depth;
425 if (code == CODE_LABEL)
427 LABEL_REFS (insn) = insn;
428 /* Any label that cannot be deleted
429 is considered to start a reachable block. */
430 if (LABEL_PRESERVE_P (insn))
435 else if (GET_RTX_CLASS (code) == 'i')
437 basic_block_end[i] = insn;
438 basic_block_loop_depth[i] = depth;
441 if (GET_RTX_CLASS (code) == 'i')
443 /* Make a list of all labels referred to other than by jumps. */
444 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
445 if (REG_NOTE_KIND (note) == REG_LABEL)
446 label_value_list = gen_rtx (EXPR_LIST, VOIDmode, XEXP (note, 0),
450 BLOCK_NUM (insn) = i;
456 /* During the second pass, `n_basic_blocks' is only an upper bound.
457 Only perform the sanity check for the first pass, and on the second
458 pass ensure `n_basic_blocks' is set to the correct value. */
459 if (pass == 1 && i + 1 != n_basic_blocks)
461 n_basic_blocks = i + 1;
463 /* Don't delete the labels (in this function)
464 that are referenced by non-jump instructions. */
466 for (x = label_value_list; x; x = XEXP (x, 1))
467 if (! LABEL_REF_NONLOCAL_P (x))
468 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
470 for (x = forced_labels; x; x = XEXP (x, 1))
471 if (! LABEL_REF_NONLOCAL_P (x))
472 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
474 for (x = exception_handler_labels; x; x = XEXP (x, 1))
475 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
477 /* Record which basic blocks control can drop in to. */
479 for (i = 0; i < n_basic_blocks; i++)
481 for (insn = PREV_INSN (basic_block_head[i]);
482 insn && GET_CODE (insn) == NOTE; insn = PREV_INSN (insn))
485 basic_block_drops_in[i] = insn && GET_CODE (insn) != BARRIER;
488 /* Now find which basic blocks can actually be reached
489 and put all jump insns' LABEL_REFS onto the ref-chains
490 of their target labels. */
492 if (n_basic_blocks > 0)
494 int something_marked = 1;
497 /* Find all indirect jump insns and mark them as possibly jumping to all
498 the labels whose addresses are explicitly used. This is because,
499 when there are computed gotos, we can't tell which labels they jump
500 to, of all the possibilities.
502 Tablejumps and casesi insns are OK and we can recognize them by
503 a (use (label_ref)). */
505 for (insn = f; insn; insn = NEXT_INSN (insn))
506 if (GET_CODE (insn) == JUMP_INSN)
508 rtx pat = PATTERN (insn);
509 int computed_jump = 0;
511 if (GET_CODE (pat) == PARALLEL)
513 int len = XVECLEN (pat, 0);
514 int has_use_labelref = 0;
516 for (i = len - 1; i >= 0; i--)
517 if (GET_CODE (XVECEXP (pat, 0, i)) == USE
518 && (GET_CODE (XEXP (XVECEXP (pat, 0, i), 0))
520 has_use_labelref = 1;
522 if (! has_use_labelref)
523 for (i = len - 1; i >= 0; i--)
524 if (GET_CODE (XVECEXP (pat, 0, i)) == SET
525 && SET_DEST (XVECEXP (pat, 0, i)) == pc_rtx
526 && jmp_uses_reg_or_mem (SET_SRC (XVECEXP (pat, 0, i))))
529 else if (GET_CODE (pat) == SET
530 && SET_DEST (pat) == pc_rtx
531 && jmp_uses_reg_or_mem (SET_SRC (pat)))
536 for (x = label_value_list; x; x = XEXP (x, 1))
537 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
540 for (x = forced_labels; x; x = XEXP (x, 1))
541 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
546 /* Find all call insns and mark them as possibly jumping
547 to all the nonlocal goto handler labels. */
549 for (insn = f; insn; insn = NEXT_INSN (insn))
550 if (GET_CODE (insn) == CALL_INSN
551 && ! find_reg_note (insn, REG_RETVAL, NULL_RTX))
553 for (x = nonlocal_label_list; x; x = XEXP (x, 1))
554 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
557 /* ??? This could be made smarter:
558 in some cases it's possible to tell that certain
559 calls will not do a nonlocal goto.
561 For example, if the nested functions that do the
562 nonlocal gotos do not have their addresses taken, then
563 only calls to those functions or to other nested
564 functions that use them could possibly do nonlocal
568 /* Pass over all blocks, marking each block that is reachable
569 and has not yet been marked.
570 Keep doing this until, in one pass, no blocks have been marked.
571 Then blocks_live and blocks_marked are identical and correct.
572 In addition, all jumps actually reachable have been marked. */
574 while (something_marked)
576 something_marked = 0;
577 for (i = 0; i < n_basic_blocks; i++)
578 if (block_live[i] && !block_marked[i])
581 something_marked = 1;
582 if (i + 1 < n_basic_blocks && basic_block_drops_in[i + 1])
583 block_live[i + 1] = 1;
584 insn = basic_block_end[i];
585 if (GET_CODE (insn) == JUMP_INSN)
586 mark_label_ref (PATTERN (insn), insn, 0);
590 /* ??? See if we have a "live" basic block that is not reachable.
591 This can happen if it is headed by a label that is preserved or
592 in one of the label lists, but no call or computed jump is in
593 the loop. It's not clear if we can delete the block or not,
594 but don't for now. However, we will mess up register status if
595 it remains unreachable, so add a fake reachability from the
598 for (i = 1; i < n_basic_blocks; i++)
599 if (block_live[i] && ! basic_block_drops_in[i]
600 && GET_CODE (basic_block_head[i]) == CODE_LABEL
601 && LABEL_REFS (basic_block_head[i]) == basic_block_head[i])
602 basic_block_drops_in[i] = 1;
604 /* Now delete the code for any basic blocks that can't be reached.
605 They can occur because jump_optimize does not recognize
606 unreachable loops as unreachable. */
609 for (i = 0; i < n_basic_blocks; i++)
614 /* Delete the insns in a (non-live) block. We physically delete
615 every non-note insn except the start and end (so
616 basic_block_head/end needn't be updated), we turn the latter
617 into NOTE_INSN_DELETED notes.
618 We use to "delete" the insns by turning them into notes, but
619 we may be deleting lots of insns that subsequent passes would
620 otherwise have to process. Secondly, lots of deleted blocks in
621 a row can really slow down propagate_block since it will
622 otherwise process insn-turned-notes multiple times when it
623 looks for loop begin/end notes. */
624 if (basic_block_head[i] != basic_block_end[i])
626 /* It would be quicker to delete all of these with a single
627 unchaining, rather than one at a time, but we need to keep
629 insn = NEXT_INSN (basic_block_head[i]);
630 while (insn != basic_block_end[i])
632 if (GET_CODE (insn) == BARRIER)
634 else if (GET_CODE (insn) != NOTE)
635 insn = flow_delete_insn (insn);
637 insn = NEXT_INSN (insn);
640 insn = basic_block_head[i];
641 if (GET_CODE (insn) != NOTE)
643 /* Turn the head into a deleted insn note. */
644 if (GET_CODE (insn) == BARRIER)
646 PUT_CODE (insn, NOTE);
647 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
648 NOTE_SOURCE_FILE (insn) = 0;
650 insn = basic_block_end[i];
651 if (GET_CODE (insn) != NOTE)
653 /* Turn the tail into a deleted insn note. */
654 if (GET_CODE (insn) == BARRIER)
656 PUT_CODE (insn, NOTE);
657 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
658 NOTE_SOURCE_FILE (insn) = 0;
660 /* BARRIERs are between basic blocks, not part of one.
661 Delete a BARRIER if the preceding jump is deleted.
662 We cannot alter a BARRIER into a NOTE
663 because it is too short; but we can really delete
664 it because it is not part of a basic block. */
665 if (NEXT_INSN (insn) != 0
666 && GET_CODE (NEXT_INSN (insn)) == BARRIER)
667 delete_insn (NEXT_INSN (insn));
669 /* Each time we delete some basic blocks,
670 see if there is a jump around them that is
671 being turned into a no-op. If so, delete it. */
673 if (block_live[i - 1])
676 for (j = i + 1; j < n_basic_blocks; j++)
680 insn = basic_block_end[i - 1];
681 if (GET_CODE (insn) == JUMP_INSN
682 /* An unconditional jump is the only possibility
683 we must check for, since a conditional one
684 would make these blocks live. */
685 && simplejump_p (insn)
686 && (label = XEXP (SET_SRC (PATTERN (insn)), 0), 1)
687 && INSN_UID (label) != 0
688 && BLOCK_NUM (label) == j)
690 PUT_CODE (insn, NOTE);
691 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
692 NOTE_SOURCE_FILE (insn) = 0;
693 if (GET_CODE (NEXT_INSN (insn)) != BARRIER)
695 delete_insn (NEXT_INSN (insn));
702 /* There are pathological cases where one function calling hundreds of
703 nested inline functions can generate lots and lots of unreachable
704 blocks that jump can't delete. Since we don't use sparse matrices
705 a lot of memory will be needed to compile such functions.
706 Implementing sparse matrices is a fair bit of work and it is not
707 clear that they win more than they lose (we don't want to
708 unnecessarily slow down compilation of normal code). By making
709 another pass for the pathological case, we can greatly speed up
710 their compilation without hurting normal code. This works because
711 all the insns in the unreachable blocks have either been deleted or
713 Note that we're talking about reducing memory usage by 10's of
714 megabytes and reducing compilation time by several minutes. */
715 /* ??? The choice of when to make another pass is a bit arbitrary,
716 and was derived from empirical data. */
721 n_basic_blocks -= deleted;
722 /* `n_basic_blocks' may not be correct at this point: two previously
723 separate blocks may now be merged. That's ok though as we
724 recalculate it during the second pass. It certainly can't be
725 any larger than the current value. */
731 /* Subroutines of find_basic_blocks. */
733 /* Return 1 if X, the SRC_SRC of SET of (pc) contain a REG or MEM that is
734 not in the constant pool and not in the condition of an IF_THEN_ELSE. */
737 jmp_uses_reg_or_mem (x)
740 enum rtx_code code = GET_CODE (x);
755 return ! (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
756 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)));
759 return (jmp_uses_reg_or_mem (XEXP (x, 1))
760 || jmp_uses_reg_or_mem (XEXP (x, 2)));
762 case PLUS: case MINUS: case MULT:
763 return (jmp_uses_reg_or_mem (XEXP (x, 0))
764 || jmp_uses_reg_or_mem (XEXP (x, 1)));
767 fmt = GET_RTX_FORMAT (code);
768 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
771 && jmp_uses_reg_or_mem (XEXP (x, i)))
775 for (j = 0; j < XVECLEN (x, i); j++)
776 if (jmp_uses_reg_or_mem (XVECEXP (x, i, j)))
783 /* Check expression X for label references;
784 if one is found, add INSN to the label's chain of references.
786 CHECKDUP means check for and avoid creating duplicate references
787 from the same insn. Such duplicates do no serious harm but
788 can slow life analysis. CHECKDUP is set only when duplicates
792 mark_label_ref (x, insn, checkdup)
796 register RTX_CODE code;
800 /* We can be called with NULL when scanning label_value_list. */
805 if (code == LABEL_REF)
807 register rtx label = XEXP (x, 0);
809 if (GET_CODE (label) != CODE_LABEL)
811 /* If the label was never emitted, this insn is junk,
812 but avoid a crash trying to refer to BLOCK_NUM (label).
813 This can happen as a result of a syntax error
814 and a diagnostic has already been printed. */
815 if (INSN_UID (label) == 0)
817 CONTAINING_INSN (x) = insn;
818 /* if CHECKDUP is set, check for duplicate ref from same insn
821 for (y = LABEL_REFS (label); y != label; y = LABEL_NEXTREF (y))
822 if (CONTAINING_INSN (y) == insn)
824 LABEL_NEXTREF (x) = LABEL_REFS (label);
825 LABEL_REFS (label) = x;
826 block_live_static[BLOCK_NUM (label)] = 1;
830 fmt = GET_RTX_FORMAT (code);
831 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
834 mark_label_ref (XEXP (x, i), insn, 0);
838 for (j = 0; j < XVECLEN (x, i); j++)
839 mark_label_ref (XVECEXP (x, i, j), insn, 1);
844 /* Delete INSN by patching it out.
845 Return the next insn. */
848 flow_delete_insn (insn)
851 /* ??? For the moment we assume we don't have to watch for NULLs here
852 since the start/end of basic blocks aren't deleted like this. */
853 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
854 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
855 return NEXT_INSN (insn);
858 /* Determine which registers are live at the start of each
859 basic block of the function whose first insn is F.
860 NREGS is the number of registers used in F.
861 We allocate the vector basic_block_live_at_start
862 and the regsets that it points to, and fill them with the data.
863 regset_size and regset_bytes are also set here. */
866 life_analysis (f, nregs)
872 /* For each basic block, a bitmask of regs
873 live on exit from the block. */
874 regset *basic_block_live_at_end;
875 /* For each basic block, a bitmask of regs
876 live on entry to a successor-block of this block.
877 If this does not match basic_block_live_at_end,
878 that must be updated, and the block must be rescanned. */
879 regset *basic_block_new_live_at_end;
880 /* For each basic block, a bitmask of regs
881 whose liveness at the end of the basic block
882 can make a difference in which regs are live on entry to the block.
883 These are the regs that are set within the basic block,
884 possibly excluding those that are used after they are set. */
885 regset *basic_block_significant;
889 struct obstack flow_obstack;
891 gcc_obstack_init (&flow_obstack);
895 bzero (regs_ever_live, sizeof regs_ever_live);
897 /* Allocate and zero out many data structures
898 that will record the data from lifetime analysis. */
900 allocate_for_life_analysis ();
902 reg_next_use = (rtx *) alloca (nregs * sizeof (rtx));
903 bzero ((char *) reg_next_use, nregs * sizeof (rtx));
905 /* Set up several regset-vectors used internally within this function.
906 Their meanings are documented above, with their declarations. */
908 basic_block_live_at_end
909 = (regset *) alloca (n_basic_blocks * sizeof (regset));
911 /* Don't use alloca since that leads to a crash rather than an error message
912 if there isn't enough space.
913 Don't use oballoc since we may need to allocate other things during
914 this function on the temporary obstack. */
915 init_regset_vector (basic_block_live_at_end, n_basic_blocks, regset_bytes,
918 basic_block_new_live_at_end
919 = (regset *) alloca (n_basic_blocks * sizeof (regset));
920 init_regset_vector (basic_block_new_live_at_end, n_basic_blocks, regset_bytes,
923 basic_block_significant
924 = (regset *) alloca (n_basic_blocks * sizeof (regset));
925 init_regset_vector (basic_block_significant, n_basic_blocks, regset_bytes,
928 /* Record which insns refer to any volatile memory
929 or for any reason can't be deleted just because they are dead stores.
930 Also, delete any insns that copy a register to itself. */
932 for (insn = f; insn; insn = NEXT_INSN (insn))
934 enum rtx_code code1 = GET_CODE (insn);
935 if (code1 == CALL_INSN)
936 INSN_VOLATILE (insn) = 1;
937 else if (code1 == INSN || code1 == JUMP_INSN)
939 /* Delete (in effect) any obvious no-op moves. */
940 if (GET_CODE (PATTERN (insn)) == SET
941 && GET_CODE (SET_DEST (PATTERN (insn))) == REG
942 && GET_CODE (SET_SRC (PATTERN (insn))) == REG
943 && (REGNO (SET_DEST (PATTERN (insn)))
944 == REGNO (SET_SRC (PATTERN (insn))))
945 /* Insns carrying these notes are useful later on. */
946 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
948 PUT_CODE (insn, NOTE);
949 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
950 NOTE_SOURCE_FILE (insn) = 0;
952 /* Delete (in effect) any obvious no-op moves. */
953 else if (GET_CODE (PATTERN (insn)) == SET
954 && GET_CODE (SET_DEST (PATTERN (insn))) == SUBREG
955 && GET_CODE (SUBREG_REG (SET_DEST (PATTERN (insn)))) == REG
956 && GET_CODE (SET_SRC (PATTERN (insn))) == SUBREG
957 && GET_CODE (SUBREG_REG (SET_SRC (PATTERN (insn)))) == REG
958 && (REGNO (SUBREG_REG (SET_DEST (PATTERN (insn))))
959 == REGNO (SUBREG_REG (SET_SRC (PATTERN (insn)))))
960 && SUBREG_WORD (SET_DEST (PATTERN (insn))) ==
961 SUBREG_WORD (SET_SRC (PATTERN (insn)))
962 /* Insns carrying these notes are useful later on. */
963 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
965 PUT_CODE (insn, NOTE);
966 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
967 NOTE_SOURCE_FILE (insn) = 0;
969 else if (GET_CODE (PATTERN (insn)) == PARALLEL)
971 /* If nothing but SETs of registers to themselves,
972 this insn can also be deleted. */
973 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
975 rtx tem = XVECEXP (PATTERN (insn), 0, i);
977 if (GET_CODE (tem) == USE
978 || GET_CODE (tem) == CLOBBER)
981 if (GET_CODE (tem) != SET
982 || GET_CODE (SET_DEST (tem)) != REG
983 || GET_CODE (SET_SRC (tem)) != REG
984 || REGNO (SET_DEST (tem)) != REGNO (SET_SRC (tem)))
988 if (i == XVECLEN (PATTERN (insn), 0)
989 /* Insns carrying these notes are useful later on. */
990 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
992 PUT_CODE (insn, NOTE);
993 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
994 NOTE_SOURCE_FILE (insn) = 0;
997 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
999 else if (GET_CODE (PATTERN (insn)) != USE)
1000 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
1001 /* A SET that makes space on the stack cannot be dead.
1002 (Such SETs occur only for allocating variable-size data,
1003 so they will always have a PLUS or MINUS according to the
1004 direction of stack growth.)
1005 Even if this function never uses this stack pointer value,
1006 signal handlers do! */
1007 else if (code1 == INSN && GET_CODE (PATTERN (insn)) == SET
1008 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1009 #ifdef STACK_GROWS_DOWNWARD
1010 && GET_CODE (SET_SRC (PATTERN (insn))) == MINUS
1012 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1014 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx)
1015 INSN_VOLATILE (insn) = 1;
1019 if (n_basic_blocks > 0)
1020 #ifdef EXIT_IGNORE_STACK
1021 if (! EXIT_IGNORE_STACK
1022 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
1025 /* If exiting needs the right stack value,
1026 consider the stack pointer live at the end of the function. */
1027 SET_REGNO_REG_SET (basic_block_live_at_end[n_basic_blocks - 1],
1028 STACK_POINTER_REGNUM);
1029 SET_REGNO_REG_SET (basic_block_new_live_at_end[n_basic_blocks - 1],
1030 STACK_POINTER_REGNUM);
1033 /* Mark the frame pointer is needed at the end of the function. If
1034 we end up eliminating it, it will be removed from the live list
1035 of each basic block by reload. */
1037 if (n_basic_blocks > 0)
1039 SET_REGNO_REG_SET (basic_block_live_at_end[n_basic_blocks - 1],
1040 FRAME_POINTER_REGNUM);
1041 SET_REGNO_REG_SET (basic_block_new_live_at_end[n_basic_blocks - 1],
1042 FRAME_POINTER_REGNUM);
1043 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1044 /* If they are different, also mark the hard frame pointer as live */
1045 SET_REGNO_REG_SET (basic_block_live_at_end[n_basic_blocks - 1],
1046 HARD_FRAME_POINTER_REGNUM);
1047 SET_REGNO_REG_SET (basic_block_new_live_at_end[n_basic_blocks - 1],
1048 HARD_FRAME_POINTER_REGNUM);
1052 /* Mark all global registers and all registers used by the epilogue
1053 as being live at the end of the function since they may be
1054 referenced by our caller. */
1056 if (n_basic_blocks > 0)
1057 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1059 #ifdef EPILOGUE_USES
1060 || EPILOGUE_USES (i)
1064 SET_REGNO_REG_SET (basic_block_live_at_end[n_basic_blocks - 1], i);
1065 SET_REGNO_REG_SET (basic_block_new_live_at_end[n_basic_blocks - 1], i);
1068 /* Propagate life info through the basic blocks
1069 around the graph of basic blocks.
1071 This is a relaxation process: each time a new register
1072 is live at the end of the basic block, we must scan the block
1073 to determine which registers are, as a consequence, live at the beginning
1074 of that block. These registers must then be marked live at the ends
1075 of all the blocks that can transfer control to that block.
1076 The process continues until it reaches a fixed point. */
1083 for (i = n_basic_blocks - 1; i >= 0; i--)
1085 int consider = first_pass;
1086 int must_rescan = first_pass;
1091 /* Set CONSIDER if this block needs thinking about at all
1092 (that is, if the regs live now at the end of it
1093 are not the same as were live at the end of it when
1094 we last thought about it).
1095 Set must_rescan if it needs to be thought about
1096 instruction by instruction (that is, if any additional
1097 reg that is live at the end now but was not live there before
1098 is one of the significant regs of this basic block). */
1100 EXECUTE_IF_AND_COMPL_IN_REG_SET (basic_block_new_live_at_end[i],
1101 basic_block_live_at_end[i],
1105 if (REGNO_REG_SET_P (basic_block_significant[i], j))
1116 /* The live_at_start of this block may be changing,
1117 so another pass will be required after this one. */
1122 /* No complete rescan needed;
1123 just record those variables newly known live at end
1124 as live at start as well. */
1125 IOR_AND_COMPL_REG_SET (basic_block_live_at_start[i],
1126 basic_block_new_live_at_end[i],
1127 basic_block_live_at_end[i]);
1129 IOR_AND_COMPL_REG_SET (basic_block_live_at_end[i],
1130 basic_block_new_live_at_end[i],
1131 basic_block_live_at_end[i]);
1135 /* Update the basic_block_live_at_start
1136 by propagation backwards through the block. */
1137 COPY_REG_SET (basic_block_live_at_end[i],
1138 basic_block_new_live_at_end[i]);
1139 COPY_REG_SET (basic_block_live_at_start[i],
1140 basic_block_live_at_end[i]);
1141 propagate_block (basic_block_live_at_start[i],
1142 basic_block_head[i], basic_block_end[i], 0,
1143 first_pass ? basic_block_significant[i]
1149 register rtx jump, head;
1151 /* Update the basic_block_new_live_at_end's of the block
1152 that falls through into this one (if any). */
1153 head = basic_block_head[i];
1154 if (basic_block_drops_in[i])
1155 IOR_REG_SET (basic_block_new_live_at_end[i-1],
1156 basic_block_live_at_start[i]);
1158 /* Update the basic_block_new_live_at_end's of
1159 all the blocks that jump to this one. */
1160 if (GET_CODE (head) == CODE_LABEL)
1161 for (jump = LABEL_REFS (head);
1163 jump = LABEL_NEXTREF (jump))
1165 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
1166 IOR_REG_SET (basic_block_new_live_at_end[from_block],
1167 basic_block_live_at_start[i]);
1177 /* The only pseudos that are live at the beginning of the function are
1178 those that were not set anywhere in the function. local-alloc doesn't
1179 know how to handle these correctly, so mark them as not local to any
1182 if (n_basic_blocks > 0)
1183 EXECUTE_IF_SET_IN_REG_SET (basic_block_live_at_start[0],
1184 FIRST_PSEUDO_REGISTER, i,
1186 REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL;
1189 /* Now the life information is accurate.
1190 Make one more pass over each basic block
1191 to delete dead stores, create autoincrement addressing
1192 and record how many times each register is used, is set, or dies.
1194 To save time, we operate directly in basic_block_live_at_end[i],
1195 thus destroying it (in fact, converting it into a copy of
1196 basic_block_live_at_start[i]). This is ok now because
1197 basic_block_live_at_end[i] is no longer used past this point. */
1201 for (i = 0; i < n_basic_blocks; i++)
1203 propagate_block (basic_block_live_at_end[i],
1204 basic_block_head[i], basic_block_end[i], 1,
1212 /* Something live during a setjmp should not be put in a register
1213 on certain machines which restore regs from stack frames
1214 rather than from the jmpbuf.
1215 But we don't need to do this for the user's variables, since
1216 ANSI says only volatile variables need this. */
1217 #ifdef LONGJMP_RESTORE_FROM_STACK
1218 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
1219 FIRST_PSEUDO_REGISTER, i,
1221 if (regno_reg_rtx[i] != 0
1222 && ! REG_USERVAR_P (regno_reg_rtx[i]))
1224 REG_LIVE_LENGTH (i) = -1;
1225 REG_BASIC_BLOCK (i) = -1;
1231 /* We have a problem with any pseudoreg that
1232 lives across the setjmp. ANSI says that if a
1233 user variable does not change in value
1234 between the setjmp and the longjmp, then the longjmp preserves it.
1235 This includes longjmp from a place where the pseudo appears dead.
1236 (In principle, the value still exists if it is in scope.)
1237 If the pseudo goes in a hard reg, some other value may occupy
1238 that hard reg where this pseudo is dead, thus clobbering the pseudo.
1239 Conclusion: such a pseudo must not go in a hard reg. */
1240 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
1241 FIRST_PSEUDO_REGISTER, i,
1243 if (regno_reg_rtx[i] != 0)
1245 REG_LIVE_LENGTH (i) = -1;
1246 REG_BASIC_BLOCK (i) = -1;
1250 obstack_free (&flow_obstack, NULL_PTR);
1253 /* Subroutines of life analysis. */
1255 /* Allocate the permanent data structures that represent the results
1256 of life analysis. Not static since used also for stupid life analysis. */
1259 allocate_for_life_analysis ()
1263 regset_size = ((max_regno + REGSET_ELT_BITS - 1) / REGSET_ELT_BITS);
1264 regset_bytes = regset_size * sizeof (*(regset) 0);
1266 /* Because both reg_scan and flow_analysis want to set up the REG_N_SETS
1267 information, explicitly reset it here. The allocation should have
1268 already happened on the previous reg_scan pass. Make sure in case
1269 some more registers were allocated. */
1270 allocate_reg_info (max_regno, FALSE, FALSE);
1272 for (i = 0; i < max_regno; i++)
1275 basic_block_live_at_start
1276 = (regset *) oballoc (n_basic_blocks * sizeof (regset));
1277 init_regset_vector (basic_block_live_at_start, n_basic_blocks, regset_bytes,
1280 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (function_obstack);
1281 CLEAR_REG_SET (regs_live_at_setjmp);
1284 /* Make each element of VECTOR point at a regset,
1285 taking the space for all those regsets from SPACE.
1286 SPACE is of type regset, but it is really as long as NELTS regsets.
1287 BYTES_PER_ELT is the number of bytes in one regset. */
1290 init_regset_vector (vector, nelts, bytes_per_elt, alloc_obstack)
1294 struct obstack *alloc_obstack;
1298 for (i = 0; i < nelts; i++)
1300 vector[i] = OBSTACK_ALLOC_REG_SET (alloc_obstack);
1301 CLEAR_REG_SET (vector[i]);
1305 /* Compute the registers live at the beginning of a basic block
1306 from those live at the end.
1308 When called, OLD contains those live at the end.
1309 On return, it contains those live at the beginning.
1310 FIRST and LAST are the first and last insns of the basic block.
1312 FINAL is nonzero if we are doing the final pass which is not
1313 for computing the life info (since that has already been done)
1314 but for acting on it. On this pass, we delete dead stores,
1315 set up the logical links and dead-variables lists of instructions,
1316 and merge instructions for autoincrement and autodecrement addresses.
1318 SIGNIFICANT is nonzero only the first time for each basic block.
1319 If it is nonzero, it points to a regset in which we store
1320 a 1 for each register that is set within the block.
1322 BNUM is the number of the basic block. */
1325 propagate_block (old, first, last, final, significant, bnum)
1326 register regset old;
1338 /* The following variables are used only if FINAL is nonzero. */
1339 /* This vector gets one element for each reg that has been live
1340 at any point in the basic block that has been scanned so far.
1341 SOMETIMES_MAX says how many elements are in use so far. */
1342 register int *regs_sometimes_live;
1343 int sometimes_max = 0;
1344 /* This regset has 1 for each reg that we have seen live so far.
1345 It and REGS_SOMETIMES_LIVE are updated together. */
1348 /* The loop depth may change in the middle of a basic block. Since we
1349 scan from end to beginning, we start with the depth at the end of the
1350 current basic block, and adjust as we pass ends and starts of loops. */
1351 loop_depth = basic_block_loop_depth[bnum];
1353 dead = ALLOCA_REG_SET ();
1354 live = ALLOCA_REG_SET ();
1359 /* Include any notes at the end of the block in the scan.
1360 This is in case the block ends with a call to setjmp. */
1362 while (NEXT_INSN (last) != 0 && GET_CODE (NEXT_INSN (last)) == NOTE)
1364 /* Look for loop boundaries, we are going forward here. */
1365 last = NEXT_INSN (last);
1366 if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_BEG)
1368 else if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_END)
1377 maxlive = ALLOCA_REG_SET ();
1378 COPY_REG_SET (maxlive, old);
1379 regs_sometimes_live = (int *) alloca (max_regno * sizeof (int));
1381 /* Process the regs live at the end of the block.
1382 Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
1383 Also mark them as not local to any one basic block. */
1384 EXECUTE_IF_SET_IN_REG_SET (old, 0, i,
1386 REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL;
1387 regs_sometimes_live[sometimes_max] = i;
1392 /* Scan the block an insn at a time from end to beginning. */
1394 for (insn = last; ; insn = prev)
1396 prev = PREV_INSN (insn);
1398 if (GET_CODE (insn) == NOTE)
1400 /* Look for loop boundaries, remembering that we are going
1402 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1404 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1407 /* If we have LOOP_DEPTH == 0, there has been a bookkeeping error.
1408 Abort now rather than setting register status incorrectly. */
1409 if (loop_depth == 0)
1412 /* If this is a call to `setjmp' et al,
1413 warn if any non-volatile datum is live. */
1415 if (final && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
1416 IOR_REG_SET (regs_live_at_setjmp, old);
1419 /* Update the life-status of regs for this insn.
1420 First DEAD gets which regs are set in this insn
1421 then LIVE gets which regs are used in this insn.
1422 Then the regs live before the insn
1423 are those live after, with DEAD regs turned off,
1424 and then LIVE regs turned on. */
1426 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
1429 rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1431 = (insn_dead_p (PATTERN (insn), old, 0)
1432 /* Don't delete something that refers to volatile storage! */
1433 && ! INSN_VOLATILE (insn));
1435 = (insn_is_dead && note != 0
1436 && libcall_dead_p (PATTERN (insn), old, note, insn));
1438 /* If an instruction consists of just dead store(s) on final pass,
1439 "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
1440 We could really delete it with delete_insn, but that
1441 can cause trouble for first or last insn in a basic block. */
1442 if (final && insn_is_dead)
1444 PUT_CODE (insn, NOTE);
1445 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
1446 NOTE_SOURCE_FILE (insn) = 0;
1448 /* CC0 is now known to be dead. Either this insn used it,
1449 in which case it doesn't anymore, or clobbered it,
1450 so the next insn can't use it. */
1453 /* If this insn is copying the return value from a library call,
1454 delete the entire library call. */
1455 if (libcall_is_dead)
1457 rtx first = XEXP (note, 0);
1459 while (INSN_DELETED_P (first))
1460 first = NEXT_INSN (first);
1465 NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED;
1466 NOTE_SOURCE_FILE (p) = 0;
1472 CLEAR_REG_SET (dead);
1473 CLEAR_REG_SET (live);
1475 /* See if this is an increment or decrement that can be
1476 merged into a following memory address. */
1479 register rtx x = PATTERN (insn);
1480 /* Does this instruction increment or decrement a register? */
1481 if (final && GET_CODE (x) == SET
1482 && GET_CODE (SET_DEST (x)) == REG
1483 && (GET_CODE (SET_SRC (x)) == PLUS
1484 || GET_CODE (SET_SRC (x)) == MINUS)
1485 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1486 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1487 /* Ok, look for a following memory ref we can combine with.
1488 If one is found, change the memory ref to a PRE_INC
1489 or PRE_DEC, cancel this insn, and return 1.
1490 Return 0 if nothing has been done. */
1491 && try_pre_increment_1 (insn))
1494 #endif /* AUTO_INC_DEC */
1496 /* If this is not the final pass, and this insn is copying the
1497 value of a library call and it's dead, don't scan the
1498 insns that perform the library call, so that the call's
1499 arguments are not marked live. */
1500 if (libcall_is_dead)
1502 /* Mark the dest reg as `significant'. */
1503 mark_set_regs (old, dead, PATTERN (insn), NULL_RTX, significant);
1505 insn = XEXP (note, 0);
1506 prev = PREV_INSN (insn);
1508 else if (GET_CODE (PATTERN (insn)) == SET
1509 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1510 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1511 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1512 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1513 /* We have an insn to pop a constant amount off the stack.
1514 (Such insns use PLUS regardless of the direction of the stack,
1515 and any insn to adjust the stack by a constant is always a pop.)
1516 These insns, if not dead stores, have no effect on life. */
1520 /* LIVE gets the regs used in INSN;
1521 DEAD gets those set by it. Dead insns don't make anything
1524 mark_set_regs (old, dead, PATTERN (insn),
1525 final ? insn : NULL_RTX, significant);
1527 /* If an insn doesn't use CC0, it becomes dead since we
1528 assume that every insn clobbers it. So show it dead here;
1529 mark_used_regs will set it live if it is referenced. */
1533 mark_used_regs (old, live, PATTERN (insn), final, insn);
1535 /* Sometimes we may have inserted something before INSN (such as
1536 a move) when we make an auto-inc. So ensure we will scan
1539 prev = PREV_INSN (insn);
1542 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1548 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1550 note = XEXP (note, 1))
1551 if (GET_CODE (XEXP (note, 0)) == USE)
1552 mark_used_regs (old, live, SET_DEST (XEXP (note, 0)),
1555 /* Each call clobbers all call-clobbered regs that are not
1556 global or fixed. Note that the function-value reg is a
1557 call-clobbered reg, and mark_set_regs has already had
1558 a chance to handle it. */
1560 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1561 if (call_used_regs[i] && ! global_regs[i]
1563 SET_REGNO_REG_SET (dead, i);
1565 /* The stack ptr is used (honorarily) by a CALL insn. */
1566 SET_REGNO_REG_SET (live, STACK_POINTER_REGNUM);
1568 /* Calls may also reference any of the global registers,
1569 so they are made live. */
1570 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1572 mark_used_regs (old, live,
1573 gen_rtx (REG, reg_raw_mode[i], i),
1576 /* Calls also clobber memory. */
1580 /* Update OLD for the registers used or set. */
1581 AND_COMPL_REG_SET (old, dead);
1582 IOR_REG_SET (old, live);
1584 if (GET_CODE (insn) == CALL_INSN && final)
1586 /* Any regs live at the time of a call instruction
1587 must not go in a register clobbered by calls.
1588 Find all regs now live and record this for them. */
1590 register int *p = regs_sometimes_live;
1592 for (i = 0; i < sometimes_max; i++, p++)
1593 if (REGNO_REG_SET_P (old, *p))
1594 REG_N_CALLS_CROSSED (*p)++;
1598 /* On final pass, add any additional sometimes-live regs
1599 into MAXLIVE and REGS_SOMETIMES_LIVE.
1600 Also update counts of how many insns each reg is live at. */
1607 EXECUTE_IF_AND_COMPL_IN_REG_SET (live, maxlive, 0, regno,
1609 regs_sometimes_live[sometimes_max++] = regno;
1610 SET_REGNO_REG_SET (maxlive, regno);
1613 p = regs_sometimes_live;
1614 for (i = 0; i < sometimes_max; i++)
1617 if (REGNO_REG_SET_P (old, regno))
1618 REG_LIVE_LENGTH (regno)++;
1627 if (num_scratch > max_scratch)
1628 max_scratch = num_scratch;
1631 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1632 (SET expressions whose destinations are registers dead after the insn).
1633 NEEDED is the regset that says which regs are alive after the insn.
1635 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */
1638 insn_dead_p (x, needed, call_ok)
1643 register RTX_CODE code = GET_CODE (x);
1644 /* If setting something that's a reg or part of one,
1645 see if that register's altered value will be live. */
1649 register rtx r = SET_DEST (x);
1650 /* A SET that is a subroutine call cannot be dead. */
1651 if (! call_ok && GET_CODE (SET_SRC (x)) == CALL)
1655 if (GET_CODE (r) == CC0)
1659 if (GET_CODE (r) == MEM && last_mem_set && ! MEM_VOLATILE_P (r)
1660 && rtx_equal_p (r, last_mem_set))
1663 while (GET_CODE (r) == SUBREG
1664 || GET_CODE (r) == STRICT_LOW_PART
1665 || GET_CODE (r) == ZERO_EXTRACT
1666 || GET_CODE (r) == SIGN_EXTRACT)
1669 if (GET_CODE (r) == REG)
1671 register int regno = REGNO (r);
1673 /* Don't delete insns to set global regs. */
1674 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
1675 /* Make sure insns to set frame pointer aren't deleted. */
1676 || regno == FRAME_POINTER_REGNUM
1677 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1678 || regno == HARD_FRAME_POINTER_REGNUM
1680 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1681 /* Make sure insns to set arg pointer are never deleted
1682 (if the arg pointer isn't fixed, there will be a USE for
1683 it, so we can treat it normally). */
1684 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1686 || REGNO_REG_SET_P (needed, regno))
1689 /* If this is a hard register, verify that subsequent words are
1691 if (regno < FIRST_PSEUDO_REGISTER)
1693 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
1696 if (REGNO_REG_SET_P (needed, regno+n))
1703 /* If performing several activities,
1704 insn is dead if each activity is individually dead.
1705 Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
1706 that's inside a PARALLEL doesn't make the insn worth keeping. */
1707 else if (code == PARALLEL)
1709 register int i = XVECLEN (x, 0);
1710 for (i--; i >= 0; i--)
1712 rtx elt = XVECEXP (x, 0, i);
1713 if (!insn_dead_p (elt, needed, call_ok)
1714 && GET_CODE (elt) != CLOBBER
1715 && GET_CODE (elt) != USE)
1720 /* We do not check CLOBBER or USE here.
1721 An insn consisting of just a CLOBBER or just a USE
1722 should not be deleted. */
1726 /* If X is the pattern of the last insn in a libcall, and assuming X is dead,
1727 return 1 if the entire library call is dead.
1728 This is true if X copies a register (hard or pseudo)
1729 and if the hard return reg of the call insn is dead.
1730 (The caller should have tested the destination of X already for death.)
1732 If this insn doesn't just copy a register, then we don't
1733 have an ordinary libcall. In that case, cse could not have
1734 managed to substitute the source for the dest later on,
1735 so we can assume the libcall is dead.
1737 NEEDED is the bit vector of pseudoregs live before this insn.
1738 NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
1741 libcall_dead_p (x, needed, note, insn)
1747 register RTX_CODE code = GET_CODE (x);
1751 register rtx r = SET_SRC (x);
1752 if (GET_CODE (r) == REG)
1754 rtx call = XEXP (note, 0);
1757 /* Find the call insn. */
1758 while (call != insn && GET_CODE (call) != CALL_INSN)
1759 call = NEXT_INSN (call);
1761 /* If there is none, do nothing special,
1762 since ordinary death handling can understand these insns. */
1766 /* See if the hard reg holding the value is dead.
1767 If this is a PARALLEL, find the call within it. */
1768 call = PATTERN (call);
1769 if (GET_CODE (call) == PARALLEL)
1771 for (i = XVECLEN (call, 0) - 1; i >= 0; i--)
1772 if (GET_CODE (XVECEXP (call, 0, i)) == SET
1773 && GET_CODE (SET_SRC (XVECEXP (call, 0, i))) == CALL)
1776 /* This may be a library call that is returning a value
1777 via invisible pointer. Do nothing special, since
1778 ordinary death handling can understand these insns. */
1782 call = XVECEXP (call, 0, i);
1785 return insn_dead_p (call, needed, 1);
1791 /* Return 1 if register REGNO was used before it was set.
1792 In other words, if it is live at function entry.
1793 Don't count global register variables or variables in registers
1794 that can be used for function arg passing, though. */
1797 regno_uninitialized (regno)
1800 if (n_basic_blocks == 0
1801 || (regno < FIRST_PSEUDO_REGISTER
1802 && (global_regs[regno] || FUNCTION_ARG_REGNO_P (regno))))
1805 return REGNO_REG_SET_P (basic_block_live_at_start[0], regno);
1808 /* 1 if register REGNO was alive at a place where `setjmp' was called
1809 and was set more than once or is an argument.
1810 Such regs may be clobbered by `longjmp'. */
1813 regno_clobbered_at_setjmp (regno)
1816 if (n_basic_blocks == 0)
1819 return ((REG_N_SETS (regno) > 1
1820 || REGNO_REG_SET_P (basic_block_live_at_start[0], regno))
1821 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
1824 /* Process the registers that are set within X.
1825 Their bits are set to 1 in the regset DEAD,
1826 because they are dead prior to this insn.
1828 If INSN is nonzero, it is the insn being processed
1829 and the fact that it is nonzero implies this is the FINAL pass
1830 in propagate_block. In this case, various info about register
1831 usage is stored, LOG_LINKS fields of insns are set up. */
1834 mark_set_regs (needed, dead, x, insn, significant)
1841 register RTX_CODE code = GET_CODE (x);
1843 if (code == SET || code == CLOBBER)
1844 mark_set_1 (needed, dead, x, insn, significant);
1845 else if (code == PARALLEL)
1848 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
1850 code = GET_CODE (XVECEXP (x, 0, i));
1851 if (code == SET || code == CLOBBER)
1852 mark_set_1 (needed, dead, XVECEXP (x, 0, i), insn, significant);
1857 /* Process a single SET rtx, X. */
1860 mark_set_1 (needed, dead, x, insn, significant)
1868 register rtx reg = SET_DEST (x);
1870 /* Modifying just one hardware register of a multi-reg value
1871 or just a byte field of a register
1872 does not mean the value from before this insn is now dead.
1873 But it does mean liveness of that register at the end of the block
1876 Within mark_set_1, however, we treat it as if the register is
1877 indeed modified. mark_used_regs will, however, also treat this
1878 register as being used. Thus, we treat these insns as setting a
1879 new value for the register as a function of its old value. This
1880 cases LOG_LINKS to be made appropriately and this will help combine. */
1882 while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
1883 || GET_CODE (reg) == SIGN_EXTRACT
1884 || GET_CODE (reg) == STRICT_LOW_PART)
1885 reg = XEXP (reg, 0);
1887 /* If we are writing into memory or into a register mentioned in the
1888 address of the last thing stored into memory, show we don't know
1889 what the last store was. If we are writing memory, save the address
1890 unless it is volatile. */
1891 if (GET_CODE (reg) == MEM
1892 || (GET_CODE (reg) == REG
1893 && last_mem_set != 0 && reg_overlap_mentioned_p (reg, last_mem_set)))
1896 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
1897 /* There are no REG_INC notes for SP, so we can't assume we'll see
1898 everything that invalidates it. To be safe, don't eliminate any
1899 stores though SP; none of them should be redundant anyway. */
1900 && ! reg_mentioned_p (stack_pointer_rtx, reg))
1903 if (GET_CODE (reg) == REG
1904 && (regno = REGNO (reg), regno != FRAME_POINTER_REGNUM)
1905 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1906 && regno != HARD_FRAME_POINTER_REGNUM
1908 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1909 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1911 && ! (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
1912 /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
1914 int some_needed = REGNO_REG_SET_P (needed, regno);
1915 int some_not_needed = ! some_needed;
1917 /* Mark it as a significant register for this basic block. */
1919 SET_REGNO_REG_SET (significant, regno);
1921 /* Mark it as as dead before this insn. */
1922 SET_REGNO_REG_SET (dead, regno);
1924 /* A hard reg in a wide mode may really be multiple registers.
1925 If so, mark all of them just like the first. */
1926 if (regno < FIRST_PSEUDO_REGISTER)
1930 /* Nothing below is needed for the stack pointer; get out asap.
1931 Eg, log links aren't needed, since combine won't use them. */
1932 if (regno == STACK_POINTER_REGNUM)
1935 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
1938 int regno_n = regno + n;
1939 int needed_regno = REGNO_REG_SET_P (needed, regno_n);
1941 SET_REGNO_REG_SET (significant, regno_n);
1943 SET_REGNO_REG_SET (dead, regno_n);
1944 some_needed |= needed_regno;
1945 some_not_needed |= ! needed_regno;
1948 /* Additional data to record if this is the final pass. */
1951 register rtx y = reg_next_use[regno];
1952 register int blocknum = BLOCK_NUM (insn);
1954 /* If this is a hard reg, record this function uses the reg. */
1956 if (regno < FIRST_PSEUDO_REGISTER)
1959 int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg));
1961 for (i = regno; i < endregno; i++)
1963 /* The next use is no longer "next", since a store
1965 reg_next_use[i] = 0;
1967 regs_ever_live[i] = 1;
1973 /* The next use is no longer "next", since a store
1975 reg_next_use[regno] = 0;
1977 /* Keep track of which basic blocks each reg appears in. */
1979 if (REG_BASIC_BLOCK (regno) == REG_BLOCK_UNKNOWN)
1980 REG_BASIC_BLOCK (regno) = blocknum;
1981 else if (REG_BASIC_BLOCK (regno) != blocknum)
1982 REG_BASIC_BLOCK (regno) = REG_BLOCK_GLOBAL;
1984 /* Count (weighted) references, stores, etc. This counts a
1985 register twice if it is modified, but that is correct. */
1986 REG_N_SETS (regno)++;
1988 REG_N_REFS (regno) += loop_depth;
1990 /* The insns where a reg is live are normally counted
1991 elsewhere, but we want the count to include the insn
1992 where the reg is set, and the normal counting mechanism
1993 would not count it. */
1994 REG_LIVE_LENGTH (regno)++;
1997 if (! some_not_needed)
1999 /* Make a logical link from the next following insn
2000 that uses this register, back to this insn.
2001 The following insns have already been processed.
2003 We don't build a LOG_LINK for hard registers containing
2004 in ASM_OPERANDs. If these registers get replaced,
2005 we might wind up changing the semantics of the insn,
2006 even if reload can make what appear to be valid assignments
2008 if (y && (BLOCK_NUM (y) == blocknum)
2009 && (regno >= FIRST_PSEUDO_REGISTER
2010 || asm_noperands (PATTERN (y)) < 0))
2012 = gen_rtx (INSN_LIST, VOIDmode, insn, LOG_LINKS (y));
2014 else if (! some_needed)
2016 /* Note that dead stores have already been deleted when possible
2017 If we get here, we have found a dead store that cannot
2018 be eliminated (because the same insn does something useful).
2019 Indicate this by marking the reg being set as dying here. */
2021 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
2022 REG_N_DEATHS (REGNO (reg))++;
2026 /* This is a case where we have a multi-word hard register
2027 and some, but not all, of the words of the register are
2028 needed in subsequent insns. Write REG_UNUSED notes
2029 for those parts that were not needed. This case should
2034 for (i = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1;
2036 if (!REGNO_REG_SET_P (needed, regno + i))
2038 = gen_rtx (EXPR_LIST, REG_UNUSED,
2039 gen_rtx (REG, reg_raw_mode[regno + i],
2045 else if (GET_CODE (reg) == REG)
2046 reg_next_use[regno] = 0;
2048 /* If this is the last pass and this is a SCRATCH, show it will be dying
2049 here and count it. */
2050 else if (GET_CODE (reg) == SCRATCH && insn != 0)
2053 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
2060 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
2064 find_auto_inc (needed, x, insn)
2069 rtx addr = XEXP (x, 0);
2070 HOST_WIDE_INT offset = 0;
2073 /* Here we detect use of an index register which might be good for
2074 postincrement, postdecrement, preincrement, or predecrement. */
2076 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
2077 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
2079 if (GET_CODE (addr) == REG)
2082 register int size = GET_MODE_SIZE (GET_MODE (x));
2085 int regno = REGNO (addr);
2087 /* Is the next use an increment that might make auto-increment? */
2088 if ((incr = reg_next_use[regno]) != 0
2089 && (set = single_set (incr)) != 0
2090 && GET_CODE (set) == SET
2091 && BLOCK_NUM (incr) == BLOCK_NUM (insn)
2092 /* Can't add side effects to jumps; if reg is spilled and
2093 reloaded, there's no way to store back the altered value. */
2094 && GET_CODE (insn) != JUMP_INSN
2095 && (y = SET_SRC (set), GET_CODE (y) == PLUS)
2096 && XEXP (y, 0) == addr
2097 && GET_CODE (XEXP (y, 1)) == CONST_INT
2099 #ifdef HAVE_POST_INCREMENT
2100 || (INTVAL (XEXP (y, 1)) == size && offset == 0)
2102 #ifdef HAVE_POST_DECREMENT
2103 || (INTVAL (XEXP (y, 1)) == - size && offset == 0)
2105 #ifdef HAVE_PRE_INCREMENT
2106 || (INTVAL (XEXP (y, 1)) == size && offset == size)
2108 #ifdef HAVE_PRE_DECREMENT
2109 || (INTVAL (XEXP (y, 1)) == - size && offset == - size)
2112 /* Make sure this reg appears only once in this insn. */
2113 && (use = find_use_as_address (PATTERN (insn), addr, offset),
2114 use != 0 && use != (rtx) 1))
2116 rtx q = SET_DEST (set);
2117 enum rtx_code inc_code = (INTVAL (XEXP (y, 1)) == size
2118 ? (offset ? PRE_INC : POST_INC)
2119 : (offset ? PRE_DEC : POST_DEC));
2121 if (dead_or_set_p (incr, addr))
2123 /* This is the simple case. Try to make the auto-inc. If
2124 we can't, we are done. Otherwise, we will do any
2125 needed updates below. */
2126 if (! validate_change (insn, &XEXP (x, 0),
2127 gen_rtx (inc_code, Pmode, addr),
2131 else if (GET_CODE (q) == REG
2132 /* PREV_INSN used here to check the semi-open interval
2134 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
2135 /* We must also check for sets of q as q may be
2136 a call clobbered hard register and there may
2137 be a call between PREV_INSN (insn) and incr. */
2138 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
2140 /* We have *p followed sometime later by q = p+size.
2141 Both p and q must be live afterward,
2142 and q is not used between INSN and it's assignment.
2143 Change it to q = p, ...*q..., q = q+size.
2144 Then fall into the usual case. */
2148 emit_move_insn (q, addr);
2149 insns = get_insns ();
2152 /* If anything in INSNS have UID's that don't fit within the
2153 extra space we allocate earlier, we can't make this auto-inc.
2154 This should never happen. */
2155 for (temp = insns; temp; temp = NEXT_INSN (temp))
2157 if (INSN_UID (temp) > max_uid_for_flow)
2159 BLOCK_NUM (temp) = BLOCK_NUM (insn);
2162 /* If we can't make the auto-inc, or can't make the
2163 replacement into Y, exit. There's no point in making
2164 the change below if we can't do the auto-inc and doing
2165 so is not correct in the pre-inc case. */
2167 validate_change (insn, &XEXP (x, 0),
2168 gen_rtx (inc_code, Pmode, q),
2170 validate_change (incr, &XEXP (y, 0), q, 1);
2171 if (! apply_change_group ())
2174 /* We now know we'll be doing this change, so emit the
2175 new insn(s) and do the updates. */
2176 emit_insns_before (insns, insn);
2178 if (basic_block_head[BLOCK_NUM (insn)] == insn)
2179 basic_block_head[BLOCK_NUM (insn)] = insns;
2181 /* INCR will become a NOTE and INSN won't contain a
2182 use of ADDR. If a use of ADDR was just placed in
2183 the insn before INSN, make that the next use.
2184 Otherwise, invalidate it. */
2185 if (GET_CODE (PREV_INSN (insn)) == INSN
2186 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
2187 && SET_SRC (PATTERN (PREV_INSN (insn))) == addr)
2188 reg_next_use[regno] = PREV_INSN (insn);
2190 reg_next_use[regno] = 0;
2195 /* REGNO is now used in INCR which is below INSN, but
2196 it previously wasn't live here. If we don't mark
2197 it as needed, we'll put a REG_DEAD note for it
2198 on this insn, which is incorrect. */
2199 SET_REGNO_REG_SET (needed, regno);
2201 /* If there are any calls between INSN and INCR, show
2202 that REGNO now crosses them. */
2203 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
2204 if (GET_CODE (temp) == CALL_INSN)
2205 REG_N_CALLS_CROSSED (regno)++;
2210 /* If we haven't returned, it means we were able to make the
2211 auto-inc, so update the status. First, record that this insn
2212 has an implicit side effect. */
2215 = gen_rtx (EXPR_LIST, REG_INC, addr, REG_NOTES (insn));
2217 /* Modify the old increment-insn to simply copy
2218 the already-incremented value of our register. */
2219 if (! validate_change (incr, &SET_SRC (set), addr, 0))
2222 /* If that makes it a no-op (copying the register into itself) delete
2223 it so it won't appear to be a "use" and a "set" of this
2225 if (SET_DEST (set) == addr)
2227 PUT_CODE (incr, NOTE);
2228 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
2229 NOTE_SOURCE_FILE (incr) = 0;
2232 if (regno >= FIRST_PSEUDO_REGISTER)
2234 /* Count an extra reference to the reg. When a reg is
2235 incremented, spilling it is worse, so we want to make
2236 that less likely. */
2237 REG_N_REFS (regno) += loop_depth;
2239 /* Count the increment as a setting of the register,
2240 even though it isn't a SET in rtl. */
2241 REG_N_SETS (regno)++;
2246 #endif /* AUTO_INC_DEC */
2248 /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
2249 This is done assuming the registers needed from X
2250 are those that have 1-bits in NEEDED.
2252 On the final pass, FINAL is 1. This means try for autoincrement
2253 and count the uses and deaths of each pseudo-reg.
2255 INSN is the containing instruction. If INSN is dead, this function is not
2259 mark_used_regs (needed, live, x, final, insn)
2266 register RTX_CODE code;
2271 code = GET_CODE (x);
2292 /* If we are clobbering a MEM, mark any registers inside the address
2294 if (GET_CODE (XEXP (x, 0)) == MEM)
2295 mark_used_regs (needed, live, XEXP (XEXP (x, 0), 0), final, insn);
2299 /* CYGNUS LOCAL dje/8176 */
2300 /* Invalidate the data for the last MEM stored, but only if MEM is
2301 something that can be stored into. */
2302 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
2303 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
2304 ; /* needn't clear last_mem_set */
2307 /* END CYGNUS LOCAL */
2311 find_auto_inc (needed, x, insn);
2316 if (GET_CODE (SUBREG_REG (x)) == REG
2317 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
2318 && (GET_MODE_SIZE (GET_MODE (x))
2319 != GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))))
2320 REG_CHANGES_SIZE (REGNO (SUBREG_REG (x))) = 1;
2322 /* While we're here, optimize this case. */
2325 /* In case the SUBREG is not of a register, don't optimize */
2326 if (GET_CODE (x) != REG)
2328 mark_used_regs (needed, live, x, final, insn);
2332 /* ... fall through ... */
2335 /* See a register other than being set
2336 => mark it as needed. */
2340 REGSET_ELT_TYPE some_needed = REGNO_REG_SET_P (needed, regno);
2341 REGSET_ELT_TYPE some_not_needed = ! some_needed;
2343 SET_REGNO_REG_SET (live, regno);
2345 /* A hard reg in a wide mode may really be multiple registers.
2346 If so, mark all of them just like the first. */
2347 if (regno < FIRST_PSEUDO_REGISTER)
2351 /* For stack ptr or fixed arg pointer,
2352 nothing below can be necessary, so waste no more time. */
2353 if (regno == STACK_POINTER_REGNUM
2354 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2355 || regno == HARD_FRAME_POINTER_REGNUM
2357 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2358 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2360 || regno == FRAME_POINTER_REGNUM)
2362 /* If this is a register we are going to try to eliminate,
2363 don't mark it live here. If we are successful in
2364 eliminating it, it need not be live unless it is used for
2365 pseudos, in which case it will have been set live when
2366 it was allocated to the pseudos. If the register will not
2367 be eliminated, reload will set it live at that point. */
2369 if (! TEST_HARD_REG_BIT (elim_reg_set, regno))
2370 regs_ever_live[regno] = 1;
2373 /* No death notes for global register variables;
2374 their values are live after this function exits. */
2375 if (global_regs[regno])
2378 reg_next_use[regno] = insn;
2382 n = HARD_REGNO_NREGS (regno, GET_MODE (x));
2385 int regno_n = regno + n;
2386 int needed_regno = REGNO_REG_SET_P (needed, regno_n);
2388 SET_REGNO_REG_SET (live, regno_n);
2389 some_needed |= needed_regno;
2390 some_not_needed != ! needed_regno;
2395 /* Record where each reg is used, so when the reg
2396 is set we know the next insn that uses it. */
2398 reg_next_use[regno] = insn;
2400 if (regno < FIRST_PSEUDO_REGISTER)
2402 /* If a hard reg is being used,
2403 record that this function does use it. */
2405 i = HARD_REGNO_NREGS (regno, GET_MODE (x));
2409 regs_ever_live[regno + --i] = 1;
2414 /* Keep track of which basic block each reg appears in. */
2416 register int blocknum = BLOCK_NUM (insn);
2418 if (REG_BASIC_BLOCK (regno) == REG_BLOCK_UNKNOWN)
2419 REG_BASIC_BLOCK (regno) = blocknum;
2420 else if (REG_BASIC_BLOCK (regno) != blocknum)
2421 REG_BASIC_BLOCK (regno) = REG_BLOCK_GLOBAL;
2423 /* Count (weighted) number of uses of each reg. */
2425 REG_N_REFS (regno) += loop_depth;
2428 /* Record and count the insns in which a reg dies.
2429 If it is used in this insn and was dead below the insn
2430 then it dies in this insn. If it was set in this insn,
2431 we do not make a REG_DEAD note; likewise if we already
2432 made such a note. */
2435 && ! dead_or_set_p (insn, x)
2437 && (regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
2441 /* Check for the case where the register dying partially
2442 overlaps the register set by this insn. */
2443 if (regno < FIRST_PSEUDO_REGISTER
2444 && HARD_REGNO_NREGS (regno, GET_MODE (x)) > 1)
2446 int n = HARD_REGNO_NREGS (regno, GET_MODE (x));
2448 some_needed |= dead_or_set_regno_p (insn, regno + n);
2451 /* If none of the words in X is needed, make a REG_DEAD
2452 note. Otherwise, we must make partial REG_DEAD notes. */
2456 = gen_rtx (EXPR_LIST, REG_DEAD, x, REG_NOTES (insn));
2457 REG_N_DEATHS (regno)++;
2463 /* Don't make a REG_DEAD note for a part of a register
2464 that is set in the insn. */
2466 for (i = HARD_REGNO_NREGS (regno, GET_MODE (x)) - 1;
2468 if (!REGNO_REG_SET_P (needed, regno + i)
2469 && ! dead_or_set_regno_p (insn, regno + i))
2471 = gen_rtx (EXPR_LIST, REG_DEAD,
2472 gen_rtx (REG, reg_raw_mode[regno + i],
2483 register rtx testreg = SET_DEST (x);
2486 /* If storing into MEM, don't show it as being used. But do
2487 show the address as being used. */
2488 if (GET_CODE (testreg) == MEM)
2492 find_auto_inc (needed, testreg, insn);
2494 mark_used_regs (needed, live, XEXP (testreg, 0), final, insn);
2495 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2499 /* Storing in STRICT_LOW_PART is like storing in a reg
2500 in that this SET might be dead, so ignore it in TESTREG.
2501 but in some other ways it is like using the reg.
2503 Storing in a SUBREG or a bit field is like storing the entire
2504 register in that if the register's value is not used
2505 then this SET is not needed. */
2506 while (GET_CODE (testreg) == STRICT_LOW_PART
2507 || GET_CODE (testreg) == ZERO_EXTRACT
2508 || GET_CODE (testreg) == SIGN_EXTRACT
2509 || GET_CODE (testreg) == SUBREG)
2511 if (GET_CODE (testreg) == SUBREG
2512 && GET_CODE (SUBREG_REG (testreg)) == REG
2513 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
2514 && (GET_MODE_SIZE (GET_MODE (testreg))
2515 != GET_MODE_SIZE (GET_MODE (SUBREG_REG (testreg)))))
2516 REG_CHANGES_SIZE (REGNO (SUBREG_REG (testreg))) = 1;
2518 /* Modifying a single register in an alternate mode
2519 does not use any of the old value. But these other
2520 ways of storing in a register do use the old value. */
2521 if (GET_CODE (testreg) == SUBREG
2522 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
2527 testreg = XEXP (testreg, 0);
2530 /* If this is a store into a register,
2531 recursively scan the value being stored. */
2533 if (GET_CODE (testreg) == REG
2534 && (regno = REGNO (testreg), regno != FRAME_POINTER_REGNUM)
2535 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2536 && regno != HARD_FRAME_POINTER_REGNUM
2538 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2539 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2542 /* We used to exclude global_regs here, but that seems wrong.
2543 Storing in them is like storing in mem. */
2545 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2547 mark_used_regs (needed, live, SET_DEST (x), final, insn);
2554 /* If exiting needs the right stack value, consider this insn as
2555 using the stack pointer. In any event, consider it as using
2556 all global registers and all registers used by return. */
2558 #ifdef EXIT_IGNORE_STACK
2559 if (! EXIT_IGNORE_STACK
2560 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
2562 SET_REGNO_REG_SET (live, STACK_POINTER_REGNUM);
2564 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2566 #ifdef EPILOGUE_USES
2567 || EPILOGUE_USES (i)
2570 SET_REGNO_REG_SET (live, i);
2574 /* Recursively scan the operands of this expression. */
2577 register char *fmt = GET_RTX_FORMAT (code);
2580 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2584 /* Tail recursive case: save a function call level. */
2590 mark_used_regs (needed, live, XEXP (x, i), final, insn);
2592 else if (fmt[i] == 'E')
2595 for (j = 0; j < XVECLEN (x, i); j++)
2596 mark_used_regs (needed, live, XVECEXP (x, i, j), final, insn);
2605 try_pre_increment_1 (insn)
2608 /* Find the next use of this reg. If in same basic block,
2609 make it do pre-increment or pre-decrement if appropriate. */
2610 rtx x = PATTERN (insn);
2611 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
2612 * INTVAL (XEXP (SET_SRC (x), 1)));
2613 int regno = REGNO (SET_DEST (x));
2614 rtx y = reg_next_use[regno];
2616 && BLOCK_NUM (y) == BLOCK_NUM (insn)
2617 /* Don't do this if the reg dies, or gets set in y; a standard addressing
2618 mode would be better. */
2619 && ! dead_or_set_p (y, SET_DEST (x))
2620 && try_pre_increment (y, SET_DEST (PATTERN (insn)),
2623 /* We have found a suitable auto-increment
2624 and already changed insn Y to do it.
2625 So flush this increment-instruction. */
2626 PUT_CODE (insn, NOTE);
2627 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
2628 NOTE_SOURCE_FILE (insn) = 0;
2629 /* Count a reference to this reg for the increment
2630 insn we are deleting. When a reg is incremented.
2631 spilling it is worse, so we want to make that
2633 if (regno >= FIRST_PSEUDO_REGISTER)
2635 REG_N_REFS (regno) += loop_depth;
2636 REG_N_SETS (regno)++;
2643 /* Try to change INSN so that it does pre-increment or pre-decrement
2644 addressing on register REG in order to add AMOUNT to REG.
2645 AMOUNT is negative for pre-decrement.
2646 Returns 1 if the change could be made.
2647 This checks all about the validity of the result of modifying INSN. */
2650 try_pre_increment (insn, reg, amount)
2652 HOST_WIDE_INT amount;
2656 /* Nonzero if we can try to make a pre-increment or pre-decrement.
2657 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
2659 /* Nonzero if we can try to make a post-increment or post-decrement.
2660 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
2661 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
2662 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
2665 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
2668 /* From the sign of increment, see which possibilities are conceivable
2669 on this target machine. */
2670 #ifdef HAVE_PRE_INCREMENT
2674 #ifdef HAVE_POST_INCREMENT
2679 #ifdef HAVE_PRE_DECREMENT
2683 #ifdef HAVE_POST_DECREMENT
2688 if (! (pre_ok || post_ok))
2691 /* It is not safe to add a side effect to a jump insn
2692 because if the incremented register is spilled and must be reloaded
2693 there would be no way to store the incremented value back in memory. */
2695 if (GET_CODE (insn) == JUMP_INSN)
2700 use = find_use_as_address (PATTERN (insn), reg, 0);
2701 if (post_ok && (use == 0 || use == (rtx) 1))
2703 use = find_use_as_address (PATTERN (insn), reg, -amount);
2707 if (use == 0 || use == (rtx) 1)
2710 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
2713 /* See if this combination of instruction and addressing mode exists. */
2714 if (! validate_change (insn, &XEXP (use, 0),
2716 ? (do_post ? POST_INC : PRE_INC)
2717 : (do_post ? POST_DEC : PRE_DEC),
2721 /* Record that this insn now has an implicit side effect on X. */
2722 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_INC, reg, REG_NOTES (insn));
2726 #endif /* AUTO_INC_DEC */
2728 /* Find the place in the rtx X where REG is used as a memory address.
2729 Return the MEM rtx that so uses it.
2730 If PLUSCONST is nonzero, search instead for a memory address equivalent to
2731 (plus REG (const_int PLUSCONST)).
2733 If such an address does not appear, return 0.
2734 If REG appears more than once, or is used other than in such an address,
2738 find_use_as_address (x, reg, plusconst)
2741 HOST_WIDE_INT plusconst;
2743 enum rtx_code code = GET_CODE (x);
2744 char *fmt = GET_RTX_FORMAT (code);
2746 register rtx value = 0;
2749 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
2752 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
2753 && XEXP (XEXP (x, 0), 0) == reg
2754 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
2755 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
2758 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
2760 /* If REG occurs inside a MEM used in a bit-field reference,
2761 that is unacceptable. */
2762 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
2763 return (rtx) (HOST_WIDE_INT) 1;
2767 return (rtx) (HOST_WIDE_INT) 1;
2769 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2773 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
2777 return (rtx) (HOST_WIDE_INT) 1;
2782 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
2784 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
2788 return (rtx) (HOST_WIDE_INT) 1;
2796 /* Write information about registers and basic blocks into FILE.
2797 This is part of making a debugging dump. */
2800 dump_flow_info (file)
2804 static char *reg_class_names[] = REG_CLASS_NAMES;
2806 fprintf (file, "%d registers.\n", max_regno);
2808 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
2811 enum reg_class class, altclass;
2812 fprintf (file, "\nRegister %d used %d times across %d insns",
2813 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
2814 if (REG_BASIC_BLOCK (i) >= 0)
2815 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
2816 if (REG_N_DEATHS (i) != 1)
2817 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
2818 if (REG_N_CALLS_CROSSED (i) == 1)
2819 fprintf (file, "; crosses 1 call");
2820 else if (REG_N_CALLS_CROSSED (i))
2821 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
2822 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
2823 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
2824 class = reg_preferred_class (i);
2825 altclass = reg_alternate_class (i);
2826 if (class != GENERAL_REGS || altclass != ALL_REGS)
2828 if (altclass == ALL_REGS || class == ALL_REGS)
2829 fprintf (file, "; pref %s", reg_class_names[(int) class]);
2830 else if (altclass == NO_REGS)
2831 fprintf (file, "; %s or none", reg_class_names[(int) class]);
2833 fprintf (file, "; pref %s, else %s",
2834 reg_class_names[(int) class],
2835 reg_class_names[(int) altclass]);
2837 if (REGNO_POINTER_FLAG (i))
2838 fprintf (file, "; pointer");
2839 fprintf (file, ".\n");
2841 fprintf (file, "\n%d basic blocks.\n", n_basic_blocks);
2842 for (i = 0; i < n_basic_blocks; i++)
2844 register rtx head, jump;
2846 fprintf (file, "\nBasic block %d: first insn %d, last %d.\n",
2848 INSN_UID (basic_block_head[i]),
2849 INSN_UID (basic_block_end[i]));
2850 /* The control flow graph's storage is freed
2851 now when flow_analysis returns.
2852 Don't try to print it if it is gone. */
2853 if (basic_block_drops_in)
2855 fprintf (file, "Reached from blocks: ");
2856 head = basic_block_head[i];
2857 if (GET_CODE (head) == CODE_LABEL)
2858 for (jump = LABEL_REFS (head);
2860 jump = LABEL_NEXTREF (jump))
2862 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
2863 fprintf (file, " %d", from_block);
2865 if (basic_block_drops_in[i])
2866 fprintf (file, " previous");
2868 fprintf (file, "\nRegisters live at start:");
2869 for (regno = 0; regno < max_regno; regno++)
2870 if (REGNO_REG_SET_P (basic_block_live_at_start[i], regno))
2871 fprintf (file, " %d", regno);
2872 fprintf (file, "\n");
2874 fprintf (file, "\n");
OSDN Git Service
