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 void mark_label_ref PROTO((rtx, rtx, int));
253 static void life_analysis PROTO((rtx, int));
254 void allocate_for_life_analysis PROTO((void));
255 void init_regset_vector PROTO((regset *, int, struct obstack *));
256 void free_regset_vector PROTO((regset *, int));
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 void dump_flow_info PROTO((FILE *));
272 /* Find basic blocks of the current function and perform data flow analysis.
273 F is the first insn of the function and NREGS the number of register numbers
277 flow_analysis (f, nregs, file)
284 rtx nonlocal_label_list = nonlocal_label_rtx_list ();
286 #ifdef ELIMINABLE_REGS
287 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
290 /* Record which registers will be eliminated. We use this in
293 CLEAR_HARD_REG_SET (elim_reg_set);
295 #ifdef ELIMINABLE_REGS
296 for (i = 0; i < sizeof eliminables / sizeof eliminables[0]; i++)
297 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
299 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
302 /* Count the basic blocks. Also find maximum insn uid value used. */
305 register RTX_CODE prev_code = JUMP_INSN;
306 register RTX_CODE code;
308 max_uid_for_flow = 0;
310 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
312 code = GET_CODE (insn);
313 if (INSN_UID (insn) > max_uid_for_flow)
314 max_uid_for_flow = INSN_UID (insn);
315 if (code == CODE_LABEL
316 || (GET_RTX_CLASS (code) == 'i'
317 && (prev_code == JUMP_INSN
318 || (prev_code == CALL_INSN
319 && nonlocal_label_list != 0)
320 || prev_code == BARRIER)))
323 if (code == CALL_INSN && find_reg_note (insn, REG_RETVAL, NULL_RTX))
332 /* Leave space for insns we make in some cases for auto-inc. These cases
333 are rare, so we don't need too much space. */
334 max_uid_for_flow += max_uid_for_flow / 10;
337 /* Allocate some tables that last till end of compiling this function
338 and some needed only in find_basic_blocks and life_analysis. */
341 basic_block_head = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
342 basic_block_end = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
343 basic_block_drops_in = (char *) alloca (n_basic_blocks);
344 basic_block_loop_depth = (short *) alloca (n_basic_blocks * sizeof (short));
346 = (int *) alloca ((max_uid_for_flow + 1) * sizeof (int));
347 uid_volatile = (char *) alloca (max_uid_for_flow + 1);
348 bzero (uid_volatile, max_uid_for_flow + 1);
350 find_basic_blocks (f, nonlocal_label_list);
351 life_analysis (f, nregs);
353 dump_flow_info (file);
355 basic_block_drops_in = 0;
356 uid_block_number = 0;
357 basic_block_loop_depth = 0;
360 /* Find all basic blocks of the function whose first insn is F.
361 Store the correct data in the tables that describe the basic blocks,
362 set up the chains of references for each CODE_LABEL, and
363 delete any entire basic blocks that cannot be reached.
365 NONLOCAL_LABEL_LIST is the same local variable from flow_analysis. */
368 find_basic_blocks (f, nonlocal_label_list)
369 rtx f, nonlocal_label_list;
373 register char *block_live = (char *) alloca (n_basic_blocks);
374 register char *block_marked = (char *) alloca (n_basic_blocks);
375 /* List of label_refs to all labels whose addresses are taken
377 rtx label_value_list;
378 int label_value_list_marked_live;
380 enum rtx_code prev_code, code;
386 label_value_list = 0;
387 label_value_list_marked_live = 0;
388 block_live_static = block_live;
389 bzero (block_live, n_basic_blocks);
390 bzero (block_marked, n_basic_blocks);
392 /* Initialize with just block 0 reachable and no blocks marked. */
393 if (n_basic_blocks > 0)
396 /* Initialize the ref chain of each label to 0. Record where all the
397 blocks start and end and their depth in loops. For each insn, record
398 the block it is in. Also mark as reachable any blocks headed by labels
399 that must not be deleted. */
401 for (insn = f, i = -1, prev_code = JUMP_INSN, depth = 1;
402 insn; insn = NEXT_INSN (insn))
404 code = GET_CODE (insn);
407 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
409 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
413 /* A basic block starts at label, or after something that can jump. */
414 else if (code == CODE_LABEL
415 || (GET_RTX_CLASS (code) == 'i'
416 && (prev_code == JUMP_INSN
417 || (prev_code == CALL_INSN
418 && nonlocal_label_list != 0
419 && ! find_reg_note (insn, REG_RETVAL, NULL_RTX))
420 || prev_code == BARRIER)))
422 basic_block_head[++i] = insn;
423 basic_block_end[i] = insn;
424 basic_block_loop_depth[i] = depth;
426 if (code == CODE_LABEL)
428 LABEL_REFS (insn) = insn;
429 /* Any label that cannot be deleted
430 is considered to start a reachable block. */
431 if (LABEL_PRESERVE_P (insn))
436 else if (GET_RTX_CLASS (code) == 'i')
438 basic_block_end[i] = insn;
439 basic_block_loop_depth[i] = depth;
442 if (GET_RTX_CLASS (code) == 'i')
444 /* Make a list of all labels referred to other than by jumps. */
445 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
446 if (REG_NOTE_KIND (note) == REG_LABEL)
447 label_value_list = gen_rtx (EXPR_LIST, VOIDmode, XEXP (note, 0),
451 BLOCK_NUM (insn) = i;
457 /* During the second pass, `n_basic_blocks' is only an upper bound.
458 Only perform the sanity check for the first pass, and on the second
459 pass ensure `n_basic_blocks' is set to the correct value. */
460 if (pass == 1 && i + 1 != n_basic_blocks)
462 n_basic_blocks = i + 1;
464 for (x = forced_labels; x; x = XEXP (x, 1))
465 if (! LABEL_REF_NONLOCAL_P (x))
466 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
468 if (asynchronous_exceptions)
469 for (x = exception_handler_labels; x; x = XEXP (x, 1))
470 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
472 /* Record which basic blocks control can drop in to. */
474 for (i = 0; i < n_basic_blocks; i++)
476 for (insn = PREV_INSN (basic_block_head[i]);
477 insn && GET_CODE (insn) == NOTE; insn = PREV_INSN (insn))
480 basic_block_drops_in[i] = insn && GET_CODE (insn) != BARRIER;
483 /* Now find which basic blocks can actually be reached
484 and put all jump insns' LABEL_REFS onto the ref-chains
485 of their target labels. */
487 if (n_basic_blocks > 0)
489 int something_marked = 1;
492 /* Find all indirect jump insns and mark them as possibly jumping to all
493 the labels whose addresses are explicitly used. This is because,
494 when there are computed gotos, we can't tell which labels they jump
495 to, of all the possibilities. */
497 for (insn = f; insn; insn = NEXT_INSN (insn))
498 if (computed_jump_p (insn))
500 if (label_value_list_marked_live == 0)
502 label_value_list_marked_live = 1;
504 /* This could be made smarter by only considering
505 these live, if the computed goto is live. */
507 /* Don't delete the labels (in this function) that
508 are referenced by non-jump instructions. */
510 for (x = label_value_list; x; x = XEXP (x, 1))
511 if (! LABEL_REF_NONLOCAL_P (x))
512 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
515 for (x = label_value_list; x; x = XEXP (x, 1))
516 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
519 for (x = forced_labels; x; x = XEXP (x, 1))
520 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
524 /* Find all call insns and mark them as possibly jumping
525 to all the nonlocal goto handler labels. */
527 for (insn = f; insn; insn = NEXT_INSN (insn))
528 if (GET_CODE (insn) == CALL_INSN
529 && ! find_reg_note (insn, REG_RETVAL, NULL_RTX))
531 for (x = nonlocal_label_list; x; x = XEXP (x, 1))
532 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
535 if (! asynchronous_exceptions)
536 for (x = exception_handler_labels; x; x = XEXP (x, 1))
537 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
540 /* ??? This could be made smarter:
541 in some cases it's possible to tell that certain
542 calls will not do a nonlocal goto.
544 For example, if the nested functions that do the
545 nonlocal gotos do not have their addresses taken, then
546 only calls to those functions or to other nested
547 functions that use them could possibly do nonlocal
551 /* All blocks associated with labels in label_value_list are
552 trivially considered as marked live, if the list is empty.
553 We do this to speed up the below code. */
555 if (label_value_list == 0)
556 label_value_list_marked_live = 1;
558 /* Pass over all blocks, marking each block that is reachable
559 and has not yet been marked.
560 Keep doing this until, in one pass, no blocks have been marked.
561 Then blocks_live and blocks_marked are identical and correct.
562 In addition, all jumps actually reachable have been marked. */
564 while (something_marked)
566 something_marked = 0;
567 for (i = 0; i < n_basic_blocks; i++)
568 if (block_live[i] && !block_marked[i])
571 something_marked = 1;
572 if (i + 1 < n_basic_blocks && basic_block_drops_in[i + 1])
573 block_live[i + 1] = 1;
574 insn = basic_block_end[i];
575 if (GET_CODE (insn) == JUMP_INSN)
576 mark_label_ref (PATTERN (insn), insn, 0);
578 if (label_value_list_marked_live == 0)
579 /* Now that we know that this block is live, mark as
580 live, all the blocks that we might be able to get
583 for (insn = basic_block_head[i];
584 insn != NEXT_INSN (basic_block_end[i]);
585 insn = NEXT_INSN (insn))
587 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
589 for (note = REG_NOTES (insn);
591 note = XEXP (note, 1))
592 if (REG_NOTE_KIND (note) == REG_LABEL)
595 block_live[BLOCK_NUM (x)] = 1;
602 /* ??? See if we have a "live" basic block that is not reachable.
603 This can happen if it is headed by a label that is preserved or
604 in one of the label lists, but no call or computed jump is in
605 the loop. It's not clear if we can delete the block or not,
606 but don't for now. However, we will mess up register status if
607 it remains unreachable, so add a fake reachability from the
610 for (i = 1; i < n_basic_blocks; i++)
611 if (block_live[i] && ! basic_block_drops_in[i]
612 && GET_CODE (basic_block_head[i]) == CODE_LABEL
613 && LABEL_REFS (basic_block_head[i]) == basic_block_head[i])
614 basic_block_drops_in[i] = 1;
616 /* Now delete the code for any basic blocks that can't be reached.
617 They can occur because jump_optimize does not recognize
618 unreachable loops as unreachable. */
621 for (i = 0; i < n_basic_blocks; i++)
626 /* Delete the insns in a (non-live) block. We physically delete
627 every non-note insn except the start and end (so
628 basic_block_head/end needn't be updated), we turn the latter
629 into NOTE_INSN_DELETED notes.
630 We use to "delete" the insns by turning them into notes, but
631 we may be deleting lots of insns that subsequent passes would
632 otherwise have to process. Secondly, lots of deleted blocks in
633 a row can really slow down propagate_block since it will
634 otherwise process insn-turned-notes multiple times when it
635 looks for loop begin/end notes. */
636 if (basic_block_head[i] != basic_block_end[i])
638 /* It would be quicker to delete all of these with a single
639 unchaining, rather than one at a time, but we need to keep
641 insn = NEXT_INSN (basic_block_head[i]);
642 while (insn != basic_block_end[i])
644 if (GET_CODE (insn) == BARRIER)
646 else if (GET_CODE (insn) != NOTE)
647 insn = flow_delete_insn (insn);
649 insn = NEXT_INSN (insn);
652 insn = basic_block_head[i];
653 if (GET_CODE (insn) != NOTE)
655 /* Turn the head into a deleted insn note. */
656 if (GET_CODE (insn) == BARRIER)
658 PUT_CODE (insn, NOTE);
659 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
660 NOTE_SOURCE_FILE (insn) = 0;
662 insn = basic_block_end[i];
663 if (GET_CODE (insn) != NOTE)
665 /* Turn the tail into a deleted insn note. */
666 if (GET_CODE (insn) == BARRIER)
668 PUT_CODE (insn, NOTE);
669 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
670 NOTE_SOURCE_FILE (insn) = 0;
672 /* BARRIERs are between basic blocks, not part of one.
673 Delete a BARRIER if the preceding jump is deleted.
674 We cannot alter a BARRIER into a NOTE
675 because it is too short; but we can really delete
676 it because it is not part of a basic block. */
677 if (NEXT_INSN (insn) != 0
678 && GET_CODE (NEXT_INSN (insn)) == BARRIER)
679 delete_insn (NEXT_INSN (insn));
681 /* Each time we delete some basic blocks,
682 see if there is a jump around them that is
683 being turned into a no-op. If so, delete it. */
685 if (block_live[i - 1])
688 for (j = i + 1; j < n_basic_blocks; j++)
692 insn = basic_block_end[i - 1];
693 if (GET_CODE (insn) == JUMP_INSN
694 /* An unconditional jump is the only possibility
695 we must check for, since a conditional one
696 would make these blocks live. */
697 && simplejump_p (insn)
698 && (label = XEXP (SET_SRC (PATTERN (insn)), 0), 1)
699 && INSN_UID (label) != 0
700 && BLOCK_NUM (label) == j)
702 PUT_CODE (insn, NOTE);
703 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
704 NOTE_SOURCE_FILE (insn) = 0;
705 if (GET_CODE (NEXT_INSN (insn)) != BARRIER)
707 delete_insn (NEXT_INSN (insn));
714 /* There are pathological cases where one function calling hundreds of
715 nested inline functions can generate lots and lots of unreachable
716 blocks that jump can't delete. Since we don't use sparse matrices
717 a lot of memory will be needed to compile such functions.
718 Implementing sparse matrices is a fair bit of work and it is not
719 clear that they win more than they lose (we don't want to
720 unnecessarily slow down compilation of normal code). By making
721 another pass for the pathological case, we can greatly speed up
722 their compilation without hurting normal code. This works because
723 all the insns in the unreachable blocks have either been deleted or
725 Note that we're talking about reducing memory usage by 10's of
726 megabytes and reducing compilation time by several minutes. */
727 /* ??? The choice of when to make another pass is a bit arbitrary,
728 and was derived from empirical data. */
733 n_basic_blocks -= deleted;
734 /* `n_basic_blocks' may not be correct at this point: two previously
735 separate blocks may now be merged. That's ok though as we
736 recalculate it during the second pass. It certainly can't be
737 any larger than the current value. */
743 /* Subroutines of find_basic_blocks. */
745 /* Check expression X for label references;
746 if one is found, add INSN to the label's chain of references.
748 CHECKDUP means check for and avoid creating duplicate references
749 from the same insn. Such duplicates do no serious harm but
750 can slow life analysis. CHECKDUP is set only when duplicates
754 mark_label_ref (x, insn, checkdup)
758 register RTX_CODE code;
762 /* We can be called with NULL when scanning label_value_list. */
767 if (code == LABEL_REF)
769 register rtx label = XEXP (x, 0);
771 if (GET_CODE (label) != CODE_LABEL)
773 /* If the label was never emitted, this insn is junk,
774 but avoid a crash trying to refer to BLOCK_NUM (label).
775 This can happen as a result of a syntax error
776 and a diagnostic has already been printed. */
777 if (INSN_UID (label) == 0)
779 CONTAINING_INSN (x) = insn;
780 /* if CHECKDUP is set, check for duplicate ref from same insn
783 for (y = LABEL_REFS (label); y != label; y = LABEL_NEXTREF (y))
784 if (CONTAINING_INSN (y) == insn)
786 LABEL_NEXTREF (x) = LABEL_REFS (label);
787 LABEL_REFS (label) = x;
788 block_live_static[BLOCK_NUM (label)] = 1;
792 fmt = GET_RTX_FORMAT (code);
793 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
796 mark_label_ref (XEXP (x, i), insn, 0);
800 for (j = 0; j < XVECLEN (x, i); j++)
801 mark_label_ref (XVECEXP (x, i, j), insn, 1);
806 /* Delete INSN by patching it out.
807 Return the next insn. */
810 flow_delete_insn (insn)
813 /* ??? For the moment we assume we don't have to watch for NULLs here
814 since the start/end of basic blocks aren't deleted like this. */
815 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
816 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
817 return NEXT_INSN (insn);
820 /* Determine which registers are live at the start of each
821 basic block of the function whose first insn is F.
822 NREGS is the number of registers used in F.
823 We allocate the vector basic_block_live_at_start
824 and the regsets that it points to, and fill them with the data.
825 regset_size and regset_bytes are also set here. */
828 life_analysis (f, nregs)
834 /* For each basic block, a bitmask of regs
835 live on exit from the block. */
836 regset *basic_block_live_at_end;
837 /* For each basic block, a bitmask of regs
838 live on entry to a successor-block of this block.
839 If this does not match basic_block_live_at_end,
840 that must be updated, and the block must be rescanned. */
841 regset *basic_block_new_live_at_end;
842 /* For each basic block, a bitmask of regs
843 whose liveness at the end of the basic block
844 can make a difference in which regs are live on entry to the block.
845 These are the regs that are set within the basic block,
846 possibly excluding those that are used after they are set. */
847 regset *basic_block_significant;
851 struct obstack flow_obstack;
853 gcc_obstack_init (&flow_obstack);
857 bzero (regs_ever_live, sizeof regs_ever_live);
859 /* Allocate and zero out many data structures
860 that will record the data from lifetime analysis. */
862 allocate_for_life_analysis ();
864 reg_next_use = (rtx *) alloca (nregs * sizeof (rtx));
865 bzero ((char *) reg_next_use, nregs * sizeof (rtx));
867 /* Set up several regset-vectors used internally within this function.
868 Their meanings are documented above, with their declarations. */
870 basic_block_live_at_end
871 = (regset *) alloca (n_basic_blocks * sizeof (regset));
873 /* Don't use alloca since that leads to a crash rather than an error message
874 if there isn't enough space.
875 Don't use oballoc since we may need to allocate other things during
876 this function on the temporary obstack. */
877 init_regset_vector (basic_block_live_at_end, n_basic_blocks, &flow_obstack);
879 basic_block_new_live_at_end
880 = (regset *) alloca (n_basic_blocks * sizeof (regset));
881 init_regset_vector (basic_block_new_live_at_end, n_basic_blocks,
884 basic_block_significant
885 = (regset *) alloca (n_basic_blocks * sizeof (regset));
886 init_regset_vector (basic_block_significant, n_basic_blocks, &flow_obstack);
888 /* Record which insns refer to any volatile memory
889 or for any reason can't be deleted just because they are dead stores.
890 Also, delete any insns that copy a register to itself. */
892 for (insn = f; insn; insn = NEXT_INSN (insn))
894 enum rtx_code code1 = GET_CODE (insn);
895 if (code1 == CALL_INSN)
896 INSN_VOLATILE (insn) = 1;
897 else if (code1 == INSN || code1 == JUMP_INSN)
899 /* Delete (in effect) any obvious no-op moves. */
900 if (GET_CODE (PATTERN (insn)) == SET
901 && GET_CODE (SET_DEST (PATTERN (insn))) == REG
902 && GET_CODE (SET_SRC (PATTERN (insn))) == REG
903 && (REGNO (SET_DEST (PATTERN (insn)))
904 == REGNO (SET_SRC (PATTERN (insn))))
905 /* Insns carrying these notes are useful later on. */
906 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
908 PUT_CODE (insn, NOTE);
909 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
910 NOTE_SOURCE_FILE (insn) = 0;
912 /* Delete (in effect) any obvious no-op moves. */
913 else if (GET_CODE (PATTERN (insn)) == SET
914 && GET_CODE (SET_DEST (PATTERN (insn))) == SUBREG
915 && GET_CODE (SUBREG_REG (SET_DEST (PATTERN (insn)))) == REG
916 && GET_CODE (SET_SRC (PATTERN (insn))) == SUBREG
917 && GET_CODE (SUBREG_REG (SET_SRC (PATTERN (insn)))) == REG
918 && (REGNO (SUBREG_REG (SET_DEST (PATTERN (insn))))
919 == REGNO (SUBREG_REG (SET_SRC (PATTERN (insn)))))
920 && SUBREG_WORD (SET_DEST (PATTERN (insn))) ==
921 SUBREG_WORD (SET_SRC (PATTERN (insn)))
922 /* Insns carrying these notes are useful later on. */
923 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
925 PUT_CODE (insn, NOTE);
926 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
927 NOTE_SOURCE_FILE (insn) = 0;
929 else if (GET_CODE (PATTERN (insn)) == PARALLEL)
931 /* If nothing but SETs of registers to themselves,
932 this insn can also be deleted. */
933 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
935 rtx tem = XVECEXP (PATTERN (insn), 0, i);
937 if (GET_CODE (tem) == USE
938 || GET_CODE (tem) == CLOBBER)
941 if (GET_CODE (tem) != SET
942 || GET_CODE (SET_DEST (tem)) != REG
943 || GET_CODE (SET_SRC (tem)) != REG
944 || REGNO (SET_DEST (tem)) != REGNO (SET_SRC (tem)))
948 if (i == XVECLEN (PATTERN (insn), 0)
949 /* Insns carrying these notes are useful later on. */
950 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
952 PUT_CODE (insn, NOTE);
953 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
954 NOTE_SOURCE_FILE (insn) = 0;
957 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
959 else if (GET_CODE (PATTERN (insn)) != USE)
960 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
961 /* A SET that makes space on the stack cannot be dead.
962 (Such SETs occur only for allocating variable-size data,
963 so they will always have a PLUS or MINUS according to the
964 direction of stack growth.)
965 Even if this function never uses this stack pointer value,
966 signal handlers do! */
967 else if (code1 == INSN && GET_CODE (PATTERN (insn)) == SET
968 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
969 #ifdef STACK_GROWS_DOWNWARD
970 && GET_CODE (SET_SRC (PATTERN (insn))) == MINUS
972 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
974 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx)
975 INSN_VOLATILE (insn) = 1;
979 if (n_basic_blocks > 0)
980 #ifdef EXIT_IGNORE_STACK
981 if (! EXIT_IGNORE_STACK
982 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
985 /* If exiting needs the right stack value,
986 consider the stack pointer live at the end of the function. */
987 SET_REGNO_REG_SET (basic_block_live_at_end[n_basic_blocks - 1],
988 STACK_POINTER_REGNUM);
989 SET_REGNO_REG_SET (basic_block_new_live_at_end[n_basic_blocks - 1],
990 STACK_POINTER_REGNUM);
993 /* Mark the frame pointer is needed at the end of the function. If
994 we end up eliminating it, it will be removed from the live list
995 of each basic block by reload. */
997 if (n_basic_blocks > 0)
999 SET_REGNO_REG_SET (basic_block_live_at_end[n_basic_blocks - 1],
1000 FRAME_POINTER_REGNUM);
1001 SET_REGNO_REG_SET (basic_block_new_live_at_end[n_basic_blocks - 1],
1002 FRAME_POINTER_REGNUM);
1003 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1004 /* If they are different, also mark the hard frame pointer as live */
1005 SET_REGNO_REG_SET (basic_block_live_at_end[n_basic_blocks - 1],
1006 HARD_FRAME_POINTER_REGNUM);
1007 SET_REGNO_REG_SET (basic_block_new_live_at_end[n_basic_blocks - 1],
1008 HARD_FRAME_POINTER_REGNUM);
1012 /* Mark all global registers and all registers used by the epilogue
1013 as being live at the end of the function since they may be
1014 referenced by our caller. */
1016 if (n_basic_blocks > 0)
1017 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1019 #ifdef EPILOGUE_USES
1020 || EPILOGUE_USES (i)
1024 SET_REGNO_REG_SET (basic_block_live_at_end[n_basic_blocks - 1], i);
1025 SET_REGNO_REG_SET (basic_block_new_live_at_end[n_basic_blocks - 1], i);
1028 /* Propagate life info through the basic blocks
1029 around the graph of basic blocks.
1031 This is a relaxation process: each time a new register
1032 is live at the end of the basic block, we must scan the block
1033 to determine which registers are, as a consequence, live at the beginning
1034 of that block. These registers must then be marked live at the ends
1035 of all the blocks that can transfer control to that block.
1036 The process continues until it reaches a fixed point. */
1043 for (i = n_basic_blocks - 1; i >= 0; i--)
1045 int consider = first_pass;
1046 int must_rescan = first_pass;
1051 /* Set CONSIDER if this block needs thinking about at all
1052 (that is, if the regs live now at the end of it
1053 are not the same as were live at the end of it when
1054 we last thought about it).
1055 Set must_rescan if it needs to be thought about
1056 instruction by instruction (that is, if any additional
1057 reg that is live at the end now but was not live there before
1058 is one of the significant regs of this basic block). */
1060 EXECUTE_IF_AND_COMPL_IN_REG_SET
1061 (basic_block_new_live_at_end[i],
1062 basic_block_live_at_end[i], 0, j,
1065 if (REGNO_REG_SET_P (basic_block_significant[i], j))
1076 /* The live_at_start of this block may be changing,
1077 so another pass will be required after this one. */
1082 /* No complete rescan needed;
1083 just record those variables newly known live at end
1084 as live at start as well. */
1085 IOR_AND_COMPL_REG_SET (basic_block_live_at_start[i],
1086 basic_block_new_live_at_end[i],
1087 basic_block_live_at_end[i]);
1089 IOR_AND_COMPL_REG_SET (basic_block_live_at_end[i],
1090 basic_block_new_live_at_end[i],
1091 basic_block_live_at_end[i]);
1095 /* Update the basic_block_live_at_start
1096 by propagation backwards through the block. */
1097 COPY_REG_SET (basic_block_live_at_end[i],
1098 basic_block_new_live_at_end[i]);
1099 COPY_REG_SET (basic_block_live_at_start[i],
1100 basic_block_live_at_end[i]);
1101 propagate_block (basic_block_live_at_start[i],
1102 basic_block_head[i], basic_block_end[i], 0,
1103 first_pass ? basic_block_significant[i]
1109 register rtx jump, head;
1111 /* Update the basic_block_new_live_at_end's of the block
1112 that falls through into this one (if any). */
1113 head = basic_block_head[i];
1114 if (basic_block_drops_in[i])
1115 IOR_REG_SET (basic_block_new_live_at_end[i-1],
1116 basic_block_live_at_start[i]);
1118 /* Update the basic_block_new_live_at_end's of
1119 all the blocks that jump to this one. */
1120 if (GET_CODE (head) == CODE_LABEL)
1121 for (jump = LABEL_REFS (head);
1123 jump = LABEL_NEXTREF (jump))
1125 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
1126 IOR_REG_SET (basic_block_new_live_at_end[from_block],
1127 basic_block_live_at_start[i]);
1137 /* The only pseudos that are live at the beginning of the function are
1138 those that were not set anywhere in the function. local-alloc doesn't
1139 know how to handle these correctly, so mark them as not local to any
1142 if (n_basic_blocks > 0)
1143 EXECUTE_IF_SET_IN_REG_SET (basic_block_live_at_start[0],
1144 FIRST_PSEUDO_REGISTER, i,
1146 REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL;
1149 /* Now the life information is accurate.
1150 Make one more pass over each basic block
1151 to delete dead stores, create autoincrement addressing
1152 and record how many times each register is used, is set, or dies.
1154 To save time, we operate directly in basic_block_live_at_end[i],
1155 thus destroying it (in fact, converting it into a copy of
1156 basic_block_live_at_start[i]). This is ok now because
1157 basic_block_live_at_end[i] is no longer used past this point. */
1161 for (i = 0; i < n_basic_blocks; i++)
1163 propagate_block (basic_block_live_at_end[i],
1164 basic_block_head[i], basic_block_end[i], 1,
1172 /* Something live during a setjmp should not be put in a register
1173 on certain machines which restore regs from stack frames
1174 rather than from the jmpbuf.
1175 But we don't need to do this for the user's variables, since
1176 ANSI says only volatile variables need this. */
1177 #ifdef LONGJMP_RESTORE_FROM_STACK
1178 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
1179 FIRST_PSEUDO_REGISTER, i,
1181 if (regno_reg_rtx[i] != 0
1182 && ! REG_USERVAR_P (regno_reg_rtx[i]))
1184 REG_LIVE_LENGTH (i) = -1;
1185 REG_BASIC_BLOCK (i) = -1;
1191 /* We have a problem with any pseudoreg that
1192 lives across the setjmp. ANSI says that if a
1193 user variable does not change in value
1194 between the setjmp and the longjmp, then the longjmp preserves it.
1195 This includes longjmp from a place where the pseudo appears dead.
1196 (In principle, the value still exists if it is in scope.)
1197 If the pseudo goes in a hard reg, some other value may occupy
1198 that hard reg where this pseudo is dead, thus clobbering the pseudo.
1199 Conclusion: such a pseudo must not go in a hard reg. */
1200 EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
1201 FIRST_PSEUDO_REGISTER, i,
1203 if (regno_reg_rtx[i] != 0)
1205 REG_LIVE_LENGTH (i) = -1;
1206 REG_BASIC_BLOCK (i) = -1;
1211 free_regset_vector (basic_block_live_at_end, n_basic_blocks);
1212 free_regset_vector (basic_block_new_live_at_end, n_basic_blocks);
1213 free_regset_vector (basic_block_significant, n_basic_blocks);
1214 basic_block_live_at_end = (regset *)0;
1215 basic_block_new_live_at_end = (regset *)0;
1216 basic_block_significant = (regset *)0;
1218 obstack_free (&flow_obstack, NULL_PTR);
1221 /* Subroutines of life analysis. */
1223 /* Allocate the permanent data structures that represent the results
1224 of life analysis. Not static since used also for stupid life analysis. */
1227 allocate_for_life_analysis ()
1231 /* Recalculate the register space, in case it has grown. Old style
1232 vector oriented regsets would set regset_{size,bytes} here also. */
1233 allocate_reg_info (max_regno, FALSE, FALSE);
1235 /* Because both reg_scan and flow_analysis want to set up the REG_N_SETS
1236 information, explicitly reset it here. The allocation should have
1237 already happened on the previous reg_scan pass. Make sure in case
1238 some more registers were allocated. */
1239 for (i = 0; i < max_regno; i++)
1242 basic_block_live_at_start
1243 = (regset *) oballoc (n_basic_blocks * sizeof (regset));
1244 init_regset_vector (basic_block_live_at_start, n_basic_blocks,
1247 regs_live_at_setjmp = OBSTACK_ALLOC_REG_SET (function_obstack);
1248 CLEAR_REG_SET (regs_live_at_setjmp);
1251 /* Make each element of VECTOR point at a regset. The vector has
1252 NELTS elements, and space is allocated from the ALLOC_OBSTACK
1256 init_regset_vector (vector, nelts, alloc_obstack)
1259 struct obstack *alloc_obstack;
1263 for (i = 0; i < nelts; i++)
1265 vector[i] = OBSTACK_ALLOC_REG_SET (alloc_obstack);
1266 CLEAR_REG_SET (vector[i]);
1270 /* Release any additional space allocated for each element of VECTOR point
1271 other than the regset header itself. The vector has NELTS elements. */
1274 free_regset_vector (vector, nelts)
1280 for (i = 0; i < nelts; i++)
1281 FREE_REG_SET (vector[i]);
1284 /* Compute the registers live at the beginning of a basic block
1285 from those live at the end.
1287 When called, OLD contains those live at the end.
1288 On return, it contains those live at the beginning.
1289 FIRST and LAST are the first and last insns of the basic block.
1291 FINAL is nonzero if we are doing the final pass which is not
1292 for computing the life info (since that has already been done)
1293 but for acting on it. On this pass, we delete dead stores,
1294 set up the logical links and dead-variables lists of instructions,
1295 and merge instructions for autoincrement and autodecrement addresses.
1297 SIGNIFICANT is nonzero only the first time for each basic block.
1298 If it is nonzero, it points to a regset in which we store
1299 a 1 for each register that is set within the block.
1301 BNUM is the number of the basic block. */
1304 propagate_block (old, first, last, final, significant, bnum)
1305 register regset old;
1317 /* The following variables are used only if FINAL is nonzero. */
1318 /* This vector gets one element for each reg that has been live
1319 at any point in the basic block that has been scanned so far.
1320 SOMETIMES_MAX says how many elements are in use so far. */
1321 register int *regs_sometimes_live;
1322 int sometimes_max = 0;
1323 /* This regset has 1 for each reg that we have seen live so far.
1324 It and REGS_SOMETIMES_LIVE are updated together. */
1327 /* The loop depth may change in the middle of a basic block. Since we
1328 scan from end to beginning, we start with the depth at the end of the
1329 current basic block, and adjust as we pass ends and starts of loops. */
1330 loop_depth = basic_block_loop_depth[bnum];
1332 dead = ALLOCA_REG_SET ();
1333 live = ALLOCA_REG_SET ();
1338 /* Include any notes at the end of the block in the scan.
1339 This is in case the block ends with a call to setjmp. */
1341 while (NEXT_INSN (last) != 0 && GET_CODE (NEXT_INSN (last)) == NOTE)
1343 /* Look for loop boundaries, we are going forward here. */
1344 last = NEXT_INSN (last);
1345 if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_BEG)
1347 else if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_END)
1356 maxlive = ALLOCA_REG_SET ();
1357 COPY_REG_SET (maxlive, old);
1358 regs_sometimes_live = (int *) alloca (max_regno * sizeof (int));
1360 /* Process the regs live at the end of the block.
1361 Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
1362 Also mark them as not local to any one basic block. */
1363 EXECUTE_IF_SET_IN_REG_SET (old, 0, i,
1365 REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL;
1366 regs_sometimes_live[sometimes_max] = i;
1371 /* Scan the block an insn at a time from end to beginning. */
1373 for (insn = last; ; insn = prev)
1375 prev = PREV_INSN (insn);
1377 if (GET_CODE (insn) == NOTE)
1379 /* Look for loop boundaries, remembering that we are going
1381 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1383 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1386 /* If we have LOOP_DEPTH == 0, there has been a bookkeeping error.
1387 Abort now rather than setting register status incorrectly. */
1388 if (loop_depth == 0)
1391 /* If this is a call to `setjmp' et al,
1392 warn if any non-volatile datum is live. */
1394 if (final && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
1395 IOR_REG_SET (regs_live_at_setjmp, old);
1398 /* Update the life-status of regs for this insn.
1399 First DEAD gets which regs are set in this insn
1400 then LIVE gets which regs are used in this insn.
1401 Then the regs live before the insn
1402 are those live after, with DEAD regs turned off,
1403 and then LIVE regs turned on. */
1405 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
1408 rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1410 = (insn_dead_p (PATTERN (insn), old, 0)
1411 /* Don't delete something that refers to volatile storage! */
1412 && ! INSN_VOLATILE (insn));
1414 = (insn_is_dead && note != 0
1415 && libcall_dead_p (PATTERN (insn), old, note, insn));
1417 /* If an instruction consists of just dead store(s) on final pass,
1418 "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
1419 We could really delete it with delete_insn, but that
1420 can cause trouble for first or last insn in a basic block. */
1421 if (final && insn_is_dead)
1423 PUT_CODE (insn, NOTE);
1424 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
1425 NOTE_SOURCE_FILE (insn) = 0;
1427 /* CC0 is now known to be dead. Either this insn used it,
1428 in which case it doesn't anymore, or clobbered it,
1429 so the next insn can't use it. */
1432 /* If this insn is copying the return value from a library call,
1433 delete the entire library call. */
1434 if (libcall_is_dead)
1436 rtx first = XEXP (note, 0);
1438 while (INSN_DELETED_P (first))
1439 first = NEXT_INSN (first);
1444 NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED;
1445 NOTE_SOURCE_FILE (p) = 0;
1451 CLEAR_REG_SET (dead);
1452 CLEAR_REG_SET (live);
1454 /* See if this is an increment or decrement that can be
1455 merged into a following memory address. */
1458 register rtx x = PATTERN (insn);
1459 /* Does this instruction increment or decrement a register? */
1460 if (final && GET_CODE (x) == SET
1461 && GET_CODE (SET_DEST (x)) == REG
1462 && (GET_CODE (SET_SRC (x)) == PLUS
1463 || GET_CODE (SET_SRC (x)) == MINUS)
1464 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1465 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1466 /* Ok, look for a following memory ref we can combine with.
1467 If one is found, change the memory ref to a PRE_INC
1468 or PRE_DEC, cancel this insn, and return 1.
1469 Return 0 if nothing has been done. */
1470 && try_pre_increment_1 (insn))
1473 #endif /* AUTO_INC_DEC */
1475 /* If this is not the final pass, and this insn is copying the
1476 value of a library call and it's dead, don't scan the
1477 insns that perform the library call, so that the call's
1478 arguments are not marked live. */
1479 if (libcall_is_dead)
1481 /* Mark the dest reg as `significant'. */
1482 mark_set_regs (old, dead, PATTERN (insn), NULL_RTX, significant);
1484 insn = XEXP (note, 0);
1485 prev = PREV_INSN (insn);
1487 else if (GET_CODE (PATTERN (insn)) == SET
1488 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1489 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1490 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1491 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1492 /* We have an insn to pop a constant amount off the stack.
1493 (Such insns use PLUS regardless of the direction of the stack,
1494 and any insn to adjust the stack by a constant is always a pop.)
1495 These insns, if not dead stores, have no effect on life. */
1499 /* LIVE gets the regs used in INSN;
1500 DEAD gets those set by it. Dead insns don't make anything
1503 mark_set_regs (old, dead, PATTERN (insn),
1504 final ? insn : NULL_RTX, significant);
1506 /* If an insn doesn't use CC0, it becomes dead since we
1507 assume that every insn clobbers it. So show it dead here;
1508 mark_used_regs will set it live if it is referenced. */
1512 mark_used_regs (old, live, PATTERN (insn), final, insn);
1514 /* Sometimes we may have inserted something before INSN (such as
1515 a move) when we make an auto-inc. So ensure we will scan
1518 prev = PREV_INSN (insn);
1521 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1527 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1529 note = XEXP (note, 1))
1530 if (GET_CODE (XEXP (note, 0)) == USE)
1531 mark_used_regs (old, live, SET_DEST (XEXP (note, 0)),
1534 /* Each call clobbers all call-clobbered regs that are not
1535 global or fixed. Note that the function-value reg is a
1536 call-clobbered reg, and mark_set_regs has already had
1537 a chance to handle it. */
1539 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1540 if (call_used_regs[i] && ! global_regs[i]
1542 SET_REGNO_REG_SET (dead, i);
1544 /* The stack ptr is used (honorarily) by a CALL insn. */
1545 SET_REGNO_REG_SET (live, STACK_POINTER_REGNUM);
1547 /* Calls may also reference any of the global registers,
1548 so they are made live. */
1549 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1551 mark_used_regs (old, live,
1552 gen_rtx (REG, reg_raw_mode[i], i),
1555 /* Calls also clobber memory. */
1559 /* Update OLD for the registers used or set. */
1560 AND_COMPL_REG_SET (old, dead);
1561 IOR_REG_SET (old, live);
1563 if (GET_CODE (insn) == CALL_INSN && final)
1565 /* Any regs live at the time of a call instruction
1566 must not go in a register clobbered by calls.
1567 Find all regs now live and record this for them. */
1569 register int *p = regs_sometimes_live;
1571 for (i = 0; i < sometimes_max; i++, p++)
1572 if (REGNO_REG_SET_P (old, *p))
1573 REG_N_CALLS_CROSSED (*p)++;
1577 /* On final pass, add any additional sometimes-live regs
1578 into MAXLIVE and REGS_SOMETIMES_LIVE.
1579 Also update counts of how many insns each reg is live at. */
1586 EXECUTE_IF_AND_COMPL_IN_REG_SET
1587 (live, maxlive, 0, regno,
1589 regs_sometimes_live[sometimes_max++] = regno;
1590 SET_REGNO_REG_SET (maxlive, regno);
1593 p = regs_sometimes_live;
1594 for (i = 0; i < sometimes_max; i++)
1597 if (REGNO_REG_SET_P (old, regno))
1598 REG_LIVE_LENGTH (regno)++;
1607 FREE_REG_SET (dead);
1608 FREE_REG_SET (live);
1610 FREE_REG_SET (maxlive);
1612 if (num_scratch > max_scratch)
1613 max_scratch = num_scratch;
1616 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1617 (SET expressions whose destinations are registers dead after the insn).
1618 NEEDED is the regset that says which regs are alive after the insn.
1620 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */
1623 insn_dead_p (x, needed, call_ok)
1628 register RTX_CODE code = GET_CODE (x);
1629 /* If setting something that's a reg or part of one,
1630 see if that register's altered value will be live. */
1634 register rtx r = SET_DEST (x);
1635 /* A SET that is a subroutine call cannot be dead. */
1636 if (! call_ok && GET_CODE (SET_SRC (x)) == CALL)
1640 if (GET_CODE (r) == CC0)
1644 if (GET_CODE (r) == MEM && last_mem_set && ! MEM_VOLATILE_P (r)
1645 && rtx_equal_p (r, last_mem_set))
1648 while (GET_CODE (r) == SUBREG
1649 || GET_CODE (r) == STRICT_LOW_PART
1650 || GET_CODE (r) == ZERO_EXTRACT
1651 || GET_CODE (r) == SIGN_EXTRACT)
1654 if (GET_CODE (r) == REG)
1656 register int regno = REGNO (r);
1658 /* Don't delete insns to set global regs. */
1659 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
1660 /* Make sure insns to set frame pointer aren't deleted. */
1661 || regno == FRAME_POINTER_REGNUM
1662 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1663 || regno == HARD_FRAME_POINTER_REGNUM
1665 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1666 /* Make sure insns to set arg pointer are never deleted
1667 (if the arg pointer isn't fixed, there will be a USE for
1668 it, so we can treat it normally). */
1669 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1671 || REGNO_REG_SET_P (needed, regno))
1674 /* If this is a hard register, verify that subsequent words are
1676 if (regno < FIRST_PSEUDO_REGISTER)
1678 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
1681 if (REGNO_REG_SET_P (needed, regno+n))
1688 /* If performing several activities,
1689 insn is dead if each activity is individually dead.
1690 Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
1691 that's inside a PARALLEL doesn't make the insn worth keeping. */
1692 else if (code == PARALLEL)
1694 register int i = XVECLEN (x, 0);
1695 for (i--; i >= 0; i--)
1697 rtx elt = XVECEXP (x, 0, i);
1698 if (!insn_dead_p (elt, needed, call_ok)
1699 && GET_CODE (elt) != CLOBBER
1700 && GET_CODE (elt) != USE)
1705 /* We do not check CLOBBER or USE here.
1706 An insn consisting of just a CLOBBER or just a USE
1707 should not be deleted. */
1711 /* If X is the pattern of the last insn in a libcall, and assuming X is dead,
1712 return 1 if the entire library call is dead.
1713 This is true if X copies a register (hard or pseudo)
1714 and if the hard return reg of the call insn is dead.
1715 (The caller should have tested the destination of X already for death.)
1717 If this insn doesn't just copy a register, then we don't
1718 have an ordinary libcall. In that case, cse could not have
1719 managed to substitute the source for the dest later on,
1720 so we can assume the libcall is dead.
1722 NEEDED is the bit vector of pseudoregs live before this insn.
1723 NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
1726 libcall_dead_p (x, needed, note, insn)
1732 register RTX_CODE code = GET_CODE (x);
1736 register rtx r = SET_SRC (x);
1737 if (GET_CODE (r) == REG)
1739 rtx call = XEXP (note, 0);
1742 /* Find the call insn. */
1743 while (call != insn && GET_CODE (call) != CALL_INSN)
1744 call = NEXT_INSN (call);
1746 /* If there is none, do nothing special,
1747 since ordinary death handling can understand these insns. */
1751 /* See if the hard reg holding the value is dead.
1752 If this is a PARALLEL, find the call within it. */
1753 call = PATTERN (call);
1754 if (GET_CODE (call) == PARALLEL)
1756 for (i = XVECLEN (call, 0) - 1; i >= 0; i--)
1757 if (GET_CODE (XVECEXP (call, 0, i)) == SET
1758 && GET_CODE (SET_SRC (XVECEXP (call, 0, i))) == CALL)
1761 /* This may be a library call that is returning a value
1762 via invisible pointer. Do nothing special, since
1763 ordinary death handling can understand these insns. */
1767 call = XVECEXP (call, 0, i);
1770 return insn_dead_p (call, needed, 1);
1776 /* Return 1 if register REGNO was used before it was set.
1777 In other words, if it is live at function entry.
1778 Don't count global register variables or variables in registers
1779 that can be used for function arg passing, though. */
1782 regno_uninitialized (regno)
1785 if (n_basic_blocks == 0
1786 || (regno < FIRST_PSEUDO_REGISTER
1787 && (global_regs[regno] || FUNCTION_ARG_REGNO_P (regno))))
1790 return REGNO_REG_SET_P (basic_block_live_at_start[0], regno);
1793 /* 1 if register REGNO was alive at a place where `setjmp' was called
1794 and was set more than once or is an argument.
1795 Such regs may be clobbered by `longjmp'. */
1798 regno_clobbered_at_setjmp (regno)
1801 if (n_basic_blocks == 0)
1804 return ((REG_N_SETS (regno) > 1
1805 || REGNO_REG_SET_P (basic_block_live_at_start[0], regno))
1806 && REGNO_REG_SET_P (regs_live_at_setjmp, regno));
1809 /* Process the registers that are set within X.
1810 Their bits are set to 1 in the regset DEAD,
1811 because they are dead prior to this insn.
1813 If INSN is nonzero, it is the insn being processed
1814 and the fact that it is nonzero implies this is the FINAL pass
1815 in propagate_block. In this case, various info about register
1816 usage is stored, LOG_LINKS fields of insns are set up. */
1819 mark_set_regs (needed, dead, x, insn, significant)
1826 register RTX_CODE code = GET_CODE (x);
1828 if (code == SET || code == CLOBBER)
1829 mark_set_1 (needed, dead, x, insn, significant);
1830 else if (code == PARALLEL)
1833 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
1835 code = GET_CODE (XVECEXP (x, 0, i));
1836 if (code == SET || code == CLOBBER)
1837 mark_set_1 (needed, dead, XVECEXP (x, 0, i), insn, significant);
1842 /* Process a single SET rtx, X. */
1845 mark_set_1 (needed, dead, x, insn, significant)
1853 register rtx reg = SET_DEST (x);
1855 /* Modifying just one hardware register of a multi-reg value
1856 or just a byte field of a register
1857 does not mean the value from before this insn is now dead.
1858 But it does mean liveness of that register at the end of the block
1861 Within mark_set_1, however, we treat it as if the register is
1862 indeed modified. mark_used_regs will, however, also treat this
1863 register as being used. Thus, we treat these insns as setting a
1864 new value for the register as a function of its old value. This
1865 cases LOG_LINKS to be made appropriately and this will help combine. */
1867 while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
1868 || GET_CODE (reg) == SIGN_EXTRACT
1869 || GET_CODE (reg) == STRICT_LOW_PART)
1870 reg = XEXP (reg, 0);
1872 /* If we are writing into memory or into a register mentioned in the
1873 address of the last thing stored into memory, show we don't know
1874 what the last store was. If we are writing memory, save the address
1875 unless it is volatile. */
1876 if (GET_CODE (reg) == MEM
1877 || (GET_CODE (reg) == REG
1878 && last_mem_set != 0 && reg_overlap_mentioned_p (reg, last_mem_set)))
1881 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
1882 /* There are no REG_INC notes for SP, so we can't assume we'll see
1883 everything that invalidates it. To be safe, don't eliminate any
1884 stores though SP; none of them should be redundant anyway. */
1885 && ! reg_mentioned_p (stack_pointer_rtx, reg))
1888 if (GET_CODE (reg) == REG
1889 && (regno = REGNO (reg), regno != FRAME_POINTER_REGNUM)
1890 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1891 && regno != HARD_FRAME_POINTER_REGNUM
1893 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1894 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1896 && ! (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
1897 /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
1899 int some_needed = REGNO_REG_SET_P (needed, regno);
1900 int some_not_needed = ! some_needed;
1902 /* Mark it as a significant register for this basic block. */
1904 SET_REGNO_REG_SET (significant, regno);
1906 /* Mark it as as dead before this insn. */
1907 SET_REGNO_REG_SET (dead, regno);
1909 /* A hard reg in a wide mode may really be multiple registers.
1910 If so, mark all of them just like the first. */
1911 if (regno < FIRST_PSEUDO_REGISTER)
1915 /* Nothing below is needed for the stack pointer; get out asap.
1916 Eg, log links aren't needed, since combine won't use them. */
1917 if (regno == STACK_POINTER_REGNUM)
1920 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
1923 int regno_n = regno + n;
1924 int needed_regno = REGNO_REG_SET_P (needed, regno_n);
1926 SET_REGNO_REG_SET (significant, regno_n);
1928 SET_REGNO_REG_SET (dead, regno_n);
1929 some_needed |= needed_regno;
1930 some_not_needed |= ! needed_regno;
1933 /* Additional data to record if this is the final pass. */
1936 register rtx y = reg_next_use[regno];
1937 register int blocknum = BLOCK_NUM (insn);
1939 /* If this is a hard reg, record this function uses the reg. */
1941 if (regno < FIRST_PSEUDO_REGISTER)
1944 int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg));
1946 for (i = regno; i < endregno; i++)
1948 /* The next use is no longer "next", since a store
1950 reg_next_use[i] = 0;
1952 regs_ever_live[i] = 1;
1958 /* The next use is no longer "next", since a store
1960 reg_next_use[regno] = 0;
1962 /* Keep track of which basic blocks each reg appears in. */
1964 if (REG_BASIC_BLOCK (regno) == REG_BLOCK_UNKNOWN)
1965 REG_BASIC_BLOCK (regno) = blocknum;
1966 else if (REG_BASIC_BLOCK (regno) != blocknum)
1967 REG_BASIC_BLOCK (regno) = REG_BLOCK_GLOBAL;
1969 /* Count (weighted) references, stores, etc. This counts a
1970 register twice if it is modified, but that is correct. */
1971 REG_N_SETS (regno)++;
1973 REG_N_REFS (regno) += loop_depth;
1975 /* The insns where a reg is live are normally counted
1976 elsewhere, but we want the count to include the insn
1977 where the reg is set, and the normal counting mechanism
1978 would not count it. */
1979 REG_LIVE_LENGTH (regno)++;
1982 if (! some_not_needed)
1984 /* Make a logical link from the next following insn
1985 that uses this register, back to this insn.
1986 The following insns have already been processed.
1988 We don't build a LOG_LINK for hard registers containing
1989 in ASM_OPERANDs. If these registers get replaced,
1990 we might wind up changing the semantics of the insn,
1991 even if reload can make what appear to be valid assignments
1993 if (y && (BLOCK_NUM (y) == blocknum)
1994 && (regno >= FIRST_PSEUDO_REGISTER
1995 || asm_noperands (PATTERN (y)) < 0))
1997 = gen_rtx (INSN_LIST, VOIDmode, insn, LOG_LINKS (y));
1999 else if (! some_needed)
2001 /* Note that dead stores have already been deleted when possible
2002 If we get here, we have found a dead store that cannot
2003 be eliminated (because the same insn does something useful).
2004 Indicate this by marking the reg being set as dying here. */
2006 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
2007 REG_N_DEATHS (REGNO (reg))++;
2011 /* This is a case where we have a multi-word hard register
2012 and some, but not all, of the words of the register are
2013 needed in subsequent insns. Write REG_UNUSED notes
2014 for those parts that were not needed. This case should
2019 for (i = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1;
2021 if (!REGNO_REG_SET_P (needed, regno + i))
2023 = gen_rtx (EXPR_LIST, REG_UNUSED,
2024 gen_rtx (REG, reg_raw_mode[regno + i],
2030 else if (GET_CODE (reg) == REG)
2031 reg_next_use[regno] = 0;
2033 /* If this is the last pass and this is a SCRATCH, show it will be dying
2034 here and count it. */
2035 else if (GET_CODE (reg) == SCRATCH && insn != 0)
2038 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
2045 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
2049 find_auto_inc (needed, x, insn)
2054 rtx addr = XEXP (x, 0);
2055 HOST_WIDE_INT offset = 0;
2058 /* Here we detect use of an index register which might be good for
2059 postincrement, postdecrement, preincrement, or predecrement. */
2061 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
2062 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
2064 if (GET_CODE (addr) == REG)
2067 register int size = GET_MODE_SIZE (GET_MODE (x));
2070 int regno = REGNO (addr);
2072 /* Is the next use an increment that might make auto-increment? */
2073 if ((incr = reg_next_use[regno]) != 0
2074 && (set = single_set (incr)) != 0
2075 && GET_CODE (set) == SET
2076 && BLOCK_NUM (incr) == BLOCK_NUM (insn)
2077 /* Can't add side effects to jumps; if reg is spilled and
2078 reloaded, there's no way to store back the altered value. */
2079 && GET_CODE (insn) != JUMP_INSN
2080 && (y = SET_SRC (set), GET_CODE (y) == PLUS)
2081 && XEXP (y, 0) == addr
2082 && GET_CODE (XEXP (y, 1)) == CONST_INT
2084 #ifdef HAVE_POST_INCREMENT
2085 || (INTVAL (XEXP (y, 1)) == size && offset == 0)
2087 #ifdef HAVE_POST_DECREMENT
2088 || (INTVAL (XEXP (y, 1)) == - size && offset == 0)
2090 #ifdef HAVE_PRE_INCREMENT
2091 || (INTVAL (XEXP (y, 1)) == size && offset == size)
2093 #ifdef HAVE_PRE_DECREMENT
2094 || (INTVAL (XEXP (y, 1)) == - size && offset == - size)
2097 /* Make sure this reg appears only once in this insn. */
2098 && (use = find_use_as_address (PATTERN (insn), addr, offset),
2099 use != 0 && use != (rtx) 1))
2101 rtx q = SET_DEST (set);
2102 enum rtx_code inc_code = (INTVAL (XEXP (y, 1)) == size
2103 ? (offset ? PRE_INC : POST_INC)
2104 : (offset ? PRE_DEC : POST_DEC));
2106 if (dead_or_set_p (incr, addr))
2108 /* This is the simple case. Try to make the auto-inc. If
2109 we can't, we are done. Otherwise, we will do any
2110 needed updates below. */
2111 if (! validate_change (insn, &XEXP (x, 0),
2112 gen_rtx (inc_code, Pmode, addr),
2116 else if (GET_CODE (q) == REG
2117 /* PREV_INSN used here to check the semi-open interval
2119 && ! reg_used_between_p (q, PREV_INSN (insn), incr)
2120 /* We must also check for sets of q as q may be
2121 a call clobbered hard register and there may
2122 be a call between PREV_INSN (insn) and incr. */
2123 && ! reg_set_between_p (q, PREV_INSN (insn), incr))
2125 /* We have *p followed sometime later by q = p+size.
2126 Both p and q must be live afterward,
2127 and q is not used between INSN and it's assignment.
2128 Change it to q = p, ...*q..., q = q+size.
2129 Then fall into the usual case. */
2133 emit_move_insn (q, addr);
2134 insns = get_insns ();
2137 /* If anything in INSNS have UID's that don't fit within the
2138 extra space we allocate earlier, we can't make this auto-inc.
2139 This should never happen. */
2140 for (temp = insns; temp; temp = NEXT_INSN (temp))
2142 if (INSN_UID (temp) > max_uid_for_flow)
2144 BLOCK_NUM (temp) = BLOCK_NUM (insn);
2147 /* If we can't make the auto-inc, or can't make the
2148 replacement into Y, exit. There's no point in making
2149 the change below if we can't do the auto-inc and doing
2150 so is not correct in the pre-inc case. */
2152 validate_change (insn, &XEXP (x, 0),
2153 gen_rtx (inc_code, Pmode, q),
2155 validate_change (incr, &XEXP (y, 0), q, 1);
2156 if (! apply_change_group ())
2159 /* We now know we'll be doing this change, so emit the
2160 new insn(s) and do the updates. */
2161 emit_insns_before (insns, insn);
2163 if (basic_block_head[BLOCK_NUM (insn)] == insn)
2164 basic_block_head[BLOCK_NUM (insn)] = insns;
2166 /* INCR will become a NOTE and INSN won't contain a
2167 use of ADDR. If a use of ADDR was just placed in
2168 the insn before INSN, make that the next use.
2169 Otherwise, invalidate it. */
2170 if (GET_CODE (PREV_INSN (insn)) == INSN
2171 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
2172 && SET_SRC (PATTERN (PREV_INSN (insn))) == addr)
2173 reg_next_use[regno] = PREV_INSN (insn);
2175 reg_next_use[regno] = 0;
2180 /* REGNO is now used in INCR which is below INSN, but
2181 it previously wasn't live here. If we don't mark
2182 it as needed, we'll put a REG_DEAD note for it
2183 on this insn, which is incorrect. */
2184 SET_REGNO_REG_SET (needed, regno);
2186 /* If there are any calls between INSN and INCR, show
2187 that REGNO now crosses them. */
2188 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
2189 if (GET_CODE (temp) == CALL_INSN)
2190 REG_N_CALLS_CROSSED (regno)++;
2195 /* If we haven't returned, it means we were able to make the
2196 auto-inc, so update the status. First, record that this insn
2197 has an implicit side effect. */
2200 = gen_rtx (EXPR_LIST, REG_INC, addr, REG_NOTES (insn));
2202 /* Modify the old increment-insn to simply copy
2203 the already-incremented value of our register. */
2204 if (! validate_change (incr, &SET_SRC (set), addr, 0))
2207 /* If that makes it a no-op (copying the register into itself) delete
2208 it so it won't appear to be a "use" and a "set" of this
2210 if (SET_DEST (set) == addr)
2212 PUT_CODE (incr, NOTE);
2213 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
2214 NOTE_SOURCE_FILE (incr) = 0;
2217 if (regno >= FIRST_PSEUDO_REGISTER)
2219 /* Count an extra reference to the reg. When a reg is
2220 incremented, spilling it is worse, so we want to make
2221 that less likely. */
2222 REG_N_REFS (regno) += loop_depth;
2224 /* Count the increment as a setting of the register,
2225 even though it isn't a SET in rtl. */
2226 REG_N_SETS (regno)++;
2231 #endif /* AUTO_INC_DEC */
2233 /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
2234 This is done assuming the registers needed from X
2235 are those that have 1-bits in NEEDED.
2237 On the final pass, FINAL is 1. This means try for autoincrement
2238 and count the uses and deaths of each pseudo-reg.
2240 INSN is the containing instruction. If INSN is dead, this function is not
2244 mark_used_regs (needed, live, x, final, insn)
2251 register RTX_CODE code;
2256 code = GET_CODE (x);
2277 /* If we are clobbering a MEM, mark any registers inside the address
2279 if (GET_CODE (XEXP (x, 0)) == MEM)
2280 mark_used_regs (needed, live, XEXP (XEXP (x, 0), 0), final, insn);
2284 /* Invalidate the data for the last MEM stored, but only if MEM is
2285 something that can be stored into. */
2286 if (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
2287 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))
2288 ; /* needn't clear last_mem_set */
2294 find_auto_inc (needed, x, insn);
2299 if (GET_CODE (SUBREG_REG (x)) == REG
2300 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
2301 && (GET_MODE_SIZE (GET_MODE (x))
2302 != GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))))
2303 REG_CHANGES_SIZE (REGNO (SUBREG_REG (x))) = 1;
2305 /* While we're here, optimize this case. */
2308 /* In case the SUBREG is not of a register, don't optimize */
2309 if (GET_CODE (x) != REG)
2311 mark_used_regs (needed, live, x, final, insn);
2315 /* ... fall through ... */
2318 /* See a register other than being set
2319 => mark it as needed. */
2323 int some_needed = REGNO_REG_SET_P (needed, regno);
2324 int some_not_needed = ! some_needed;
2326 SET_REGNO_REG_SET (live, regno);
2328 /* A hard reg in a wide mode may really be multiple registers.
2329 If so, mark all of them just like the first. */
2330 if (regno < FIRST_PSEUDO_REGISTER)
2334 /* For stack ptr or fixed arg pointer,
2335 nothing below can be necessary, so waste no more time. */
2336 if (regno == STACK_POINTER_REGNUM
2337 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2338 || regno == HARD_FRAME_POINTER_REGNUM
2340 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2341 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2343 || regno == FRAME_POINTER_REGNUM)
2345 /* If this is a register we are going to try to eliminate,
2346 don't mark it live here. If we are successful in
2347 eliminating it, it need not be live unless it is used for
2348 pseudos, in which case it will have been set live when
2349 it was allocated to the pseudos. If the register will not
2350 be eliminated, reload will set it live at that point. */
2352 if (! TEST_HARD_REG_BIT (elim_reg_set, regno))
2353 regs_ever_live[regno] = 1;
2356 /* No death notes for global register variables;
2357 their values are live after this function exits. */
2358 if (global_regs[regno])
2361 reg_next_use[regno] = insn;
2365 n = HARD_REGNO_NREGS (regno, GET_MODE (x));
2368 int regno_n = regno + n;
2369 int needed_regno = REGNO_REG_SET_P (needed, regno_n);
2371 SET_REGNO_REG_SET (live, regno_n);
2372 some_needed |= needed_regno;
2373 some_not_needed |= ! needed_regno;
2378 /* Record where each reg is used, so when the reg
2379 is set we know the next insn that uses it. */
2381 reg_next_use[regno] = insn;
2383 if (regno < FIRST_PSEUDO_REGISTER)
2385 /* If a hard reg is being used,
2386 record that this function does use it. */
2388 i = HARD_REGNO_NREGS (regno, GET_MODE (x));
2392 regs_ever_live[regno + --i] = 1;
2397 /* Keep track of which basic block each reg appears in. */
2399 register int blocknum = BLOCK_NUM (insn);
2401 if (REG_BASIC_BLOCK (regno) == REG_BLOCK_UNKNOWN)
2402 REG_BASIC_BLOCK (regno) = blocknum;
2403 else if (REG_BASIC_BLOCK (regno) != blocknum)
2404 REG_BASIC_BLOCK (regno) = REG_BLOCK_GLOBAL;
2406 /* Count (weighted) number of uses of each reg. */
2408 REG_N_REFS (regno) += loop_depth;
2411 /* Record and count the insns in which a reg dies.
2412 If it is used in this insn and was dead below the insn
2413 then it dies in this insn. If it was set in this insn,
2414 we do not make a REG_DEAD note; likewise if we already
2415 made such a note. */
2418 && ! dead_or_set_p (insn, x)
2420 && (regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
2424 /* Check for the case where the register dying partially
2425 overlaps the register set by this insn. */
2426 if (regno < FIRST_PSEUDO_REGISTER
2427 && HARD_REGNO_NREGS (regno, GET_MODE (x)) > 1)
2429 int n = HARD_REGNO_NREGS (regno, GET_MODE (x));
2431 some_needed |= dead_or_set_regno_p (insn, regno + n);
2434 /* If none of the words in X is needed, make a REG_DEAD
2435 note. Otherwise, we must make partial REG_DEAD notes. */
2439 = gen_rtx (EXPR_LIST, REG_DEAD, x, REG_NOTES (insn));
2440 REG_N_DEATHS (regno)++;
2446 /* Don't make a REG_DEAD note for a part of a register
2447 that is set in the insn. */
2449 for (i = HARD_REGNO_NREGS (regno, GET_MODE (x)) - 1;
2451 if (!REGNO_REG_SET_P (needed, regno + i)
2452 && ! dead_or_set_regno_p (insn, regno + i))
2454 = gen_rtx (EXPR_LIST, REG_DEAD,
2455 gen_rtx (REG, reg_raw_mode[regno + i],
2466 register rtx testreg = SET_DEST (x);
2469 /* If storing into MEM, don't show it as being used. But do
2470 show the address as being used. */
2471 if (GET_CODE (testreg) == MEM)
2475 find_auto_inc (needed, testreg, insn);
2477 mark_used_regs (needed, live, XEXP (testreg, 0), final, insn);
2478 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2482 /* Storing in STRICT_LOW_PART is like storing in a reg
2483 in that this SET might be dead, so ignore it in TESTREG.
2484 but in some other ways it is like using the reg.
2486 Storing in a SUBREG or a bit field is like storing the entire
2487 register in that if the register's value is not used
2488 then this SET is not needed. */
2489 while (GET_CODE (testreg) == STRICT_LOW_PART
2490 || GET_CODE (testreg) == ZERO_EXTRACT
2491 || GET_CODE (testreg) == SIGN_EXTRACT
2492 || GET_CODE (testreg) == SUBREG)
2494 if (GET_CODE (testreg) == SUBREG
2495 && GET_CODE (SUBREG_REG (testreg)) == REG
2496 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
2497 && (GET_MODE_SIZE (GET_MODE (testreg))
2498 != GET_MODE_SIZE (GET_MODE (SUBREG_REG (testreg)))))
2499 REG_CHANGES_SIZE (REGNO (SUBREG_REG (testreg))) = 1;
2501 /* Modifying a single register in an alternate mode
2502 does not use any of the old value. But these other
2503 ways of storing in a register do use the old value. */
2504 if (GET_CODE (testreg) == SUBREG
2505 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
2510 testreg = XEXP (testreg, 0);
2513 /* If this is a store into a register,
2514 recursively scan the value being stored. */
2516 if (GET_CODE (testreg) == REG
2517 && (regno = REGNO (testreg), regno != FRAME_POINTER_REGNUM)
2518 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2519 && regno != HARD_FRAME_POINTER_REGNUM
2521 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2522 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2525 /* We used to exclude global_regs here, but that seems wrong.
2526 Storing in them is like storing in mem. */
2528 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2530 mark_used_regs (needed, live, SET_DEST (x), final, insn);
2537 /* If exiting needs the right stack value, consider this insn as
2538 using the stack pointer. In any event, consider it as using
2539 all global registers and all registers used by return. */
2541 #ifdef EXIT_IGNORE_STACK
2542 if (! EXIT_IGNORE_STACK
2543 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
2545 SET_REGNO_REG_SET (live, STACK_POINTER_REGNUM);
2547 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2549 #ifdef EPILOGUE_USES
2550 || EPILOGUE_USES (i)
2553 SET_REGNO_REG_SET (live, i);
2557 /* Recursively scan the operands of this expression. */
2560 register char *fmt = GET_RTX_FORMAT (code);
2563 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2567 /* Tail recursive case: save a function call level. */
2573 mark_used_regs (needed, live, XEXP (x, i), final, insn);
2575 else if (fmt[i] == 'E')
2578 for (j = 0; j < XVECLEN (x, i); j++)
2579 mark_used_regs (needed, live, XVECEXP (x, i, j), final, insn);
2588 try_pre_increment_1 (insn)
2591 /* Find the next use of this reg. If in same basic block,
2592 make it do pre-increment or pre-decrement if appropriate. */
2593 rtx x = PATTERN (insn);
2594 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
2595 * INTVAL (XEXP (SET_SRC (x), 1)));
2596 int regno = REGNO (SET_DEST (x));
2597 rtx y = reg_next_use[regno];
2599 && BLOCK_NUM (y) == BLOCK_NUM (insn)
2600 /* Don't do this if the reg dies, or gets set in y; a standard addressing
2601 mode would be better. */
2602 && ! dead_or_set_p (y, SET_DEST (x))
2603 && try_pre_increment (y, SET_DEST (PATTERN (insn)),
2606 /* We have found a suitable auto-increment
2607 and already changed insn Y to do it.
2608 So flush this increment-instruction. */
2609 PUT_CODE (insn, NOTE);
2610 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
2611 NOTE_SOURCE_FILE (insn) = 0;
2612 /* Count a reference to this reg for the increment
2613 insn we are deleting. When a reg is incremented.
2614 spilling it is worse, so we want to make that
2616 if (regno >= FIRST_PSEUDO_REGISTER)
2618 REG_N_REFS (regno) += loop_depth;
2619 REG_N_SETS (regno)++;
2626 /* Try to change INSN so that it does pre-increment or pre-decrement
2627 addressing on register REG in order to add AMOUNT to REG.
2628 AMOUNT is negative for pre-decrement.
2629 Returns 1 if the change could be made.
2630 This checks all about the validity of the result of modifying INSN. */
2633 try_pre_increment (insn, reg, amount)
2635 HOST_WIDE_INT amount;
2639 /* Nonzero if we can try to make a pre-increment or pre-decrement.
2640 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
2642 /* Nonzero if we can try to make a post-increment or post-decrement.
2643 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
2644 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
2645 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
2648 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
2651 /* From the sign of increment, see which possibilities are conceivable
2652 on this target machine. */
2653 #ifdef HAVE_PRE_INCREMENT
2657 #ifdef HAVE_POST_INCREMENT
2662 #ifdef HAVE_PRE_DECREMENT
2666 #ifdef HAVE_POST_DECREMENT
2671 if (! (pre_ok || post_ok))
2674 /* It is not safe to add a side effect to a jump insn
2675 because if the incremented register is spilled and must be reloaded
2676 there would be no way to store the incremented value back in memory. */
2678 if (GET_CODE (insn) == JUMP_INSN)
2683 use = find_use_as_address (PATTERN (insn), reg, 0);
2684 if (post_ok && (use == 0 || use == (rtx) 1))
2686 use = find_use_as_address (PATTERN (insn), reg, -amount);
2690 if (use == 0 || use == (rtx) 1)
2693 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
2696 /* See if this combination of instruction and addressing mode exists. */
2697 if (! validate_change (insn, &XEXP (use, 0),
2699 ? (do_post ? POST_INC : PRE_INC)
2700 : (do_post ? POST_DEC : PRE_DEC),
2704 /* Record that this insn now has an implicit side effect on X. */
2705 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_INC, reg, REG_NOTES (insn));
2709 #endif /* AUTO_INC_DEC */
2711 /* Find the place in the rtx X where REG is used as a memory address.
2712 Return the MEM rtx that so uses it.
2713 If PLUSCONST is nonzero, search instead for a memory address equivalent to
2714 (plus REG (const_int PLUSCONST)).
2716 If such an address does not appear, return 0.
2717 If REG appears more than once, or is used other than in such an address,
2721 find_use_as_address (x, reg, plusconst)
2724 HOST_WIDE_INT plusconst;
2726 enum rtx_code code = GET_CODE (x);
2727 char *fmt = GET_RTX_FORMAT (code);
2729 register rtx value = 0;
2732 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
2735 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
2736 && XEXP (XEXP (x, 0), 0) == reg
2737 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
2738 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
2741 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
2743 /* If REG occurs inside a MEM used in a bit-field reference,
2744 that is unacceptable. */
2745 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
2746 return (rtx) (HOST_WIDE_INT) 1;
2750 return (rtx) (HOST_WIDE_INT) 1;
2752 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2756 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
2760 return (rtx) (HOST_WIDE_INT) 1;
2765 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
2767 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
2771 return (rtx) (HOST_WIDE_INT) 1;
2779 /* Write information about registers and basic blocks into FILE.
2780 This is part of making a debugging dump. */
2783 dump_flow_info (file)
2787 static char *reg_class_names[] = REG_CLASS_NAMES;
2789 fprintf (file, "%d registers.\n", max_regno);
2791 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
2794 enum reg_class class, altclass;
2795 fprintf (file, "\nRegister %d used %d times across %d insns",
2796 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
2797 if (REG_BASIC_BLOCK (i) >= 0)
2798 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
2799 if (REG_N_DEATHS (i) != 1)
2800 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
2801 if (REG_N_CALLS_CROSSED (i) == 1)
2802 fprintf (file, "; crosses 1 call");
2803 else if (REG_N_CALLS_CROSSED (i))
2804 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
2805 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
2806 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
2807 class = reg_preferred_class (i);
2808 altclass = reg_alternate_class (i);
2809 if (class != GENERAL_REGS || altclass != ALL_REGS)
2811 if (altclass == ALL_REGS || class == ALL_REGS)
2812 fprintf (file, "; pref %s", reg_class_names[(int) class]);
2813 else if (altclass == NO_REGS)
2814 fprintf (file, "; %s or none", reg_class_names[(int) class]);
2816 fprintf (file, "; pref %s, else %s",
2817 reg_class_names[(int) class],
2818 reg_class_names[(int) altclass]);
2820 if (REGNO_POINTER_FLAG (i))
2821 fprintf (file, "; pointer");
2822 fprintf (file, ".\n");
2824 fprintf (file, "\n%d basic blocks.\n", n_basic_blocks);
2825 for (i = 0; i < n_basic_blocks; i++)
2827 register rtx head, jump;
2829 fprintf (file, "\nBasic block %d: first insn %d, last %d.\n",
2831 INSN_UID (basic_block_head[i]),
2832 INSN_UID (basic_block_end[i]));
2833 /* The control flow graph's storage is freed
2834 now when flow_analysis returns.
2835 Don't try to print it if it is gone. */
2836 if (basic_block_drops_in)
2838 fprintf (file, "Reached from blocks: ");
2839 head = basic_block_head[i];
2840 if (GET_CODE (head) == CODE_LABEL)
2841 for (jump = LABEL_REFS (head);
2843 jump = LABEL_NEXTREF (jump))
2845 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
2846 fprintf (file, " %d", from_block);
2848 if (basic_block_drops_in[i])
2849 fprintf (file, " previous");
2851 fprintf (file, "\nRegisters live at start:");
2852 for (regno = 0; regno < max_regno; regno++)
2853 if (REGNO_REG_SET_P (basic_block_live_at_start[i], regno))
2854 fprintf (file, " %d", regno);
2855 fprintf (file, "\n");
2857 fprintf (file, "\n");
2861 /* Like print_rtl, but also print out live information for the start of each
2865 print_rtl_with_bb (outf, rtx_first)
2869 register rtx tmp_rtx;
2872 fprintf (outf, "(nil)\n");
2877 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
2878 int max_uid = get_max_uid ();
2879 int *start = (int *) alloca (max_uid * sizeof (int));
2880 int *end = (int *) alloca (max_uid * sizeof (int));
2881 char *in_bb_p = (char *) alloca (max_uid * sizeof (enum bb_state));
2883 for (i = 0; i < max_uid; i++)
2885 start[i] = end[i] = -1;
2886 in_bb_p[i] = NOT_IN_BB;
2889 for (i = n_basic_blocks-1; i >= 0; i--)
2892 start[INSN_UID (basic_block_head[i])] = i;
2893 end[INSN_UID (basic_block_end[i])] = i;
2894 for (x = basic_block_head[i]; x != NULL_RTX; x = NEXT_INSN (x))
2896 in_bb_p[ INSN_UID(x)]
2897 = (in_bb_p[ INSN_UID(x)] == NOT_IN_BB)
2898 ? IN_ONE_BB : IN_MULTIPLE_BB;
2899 if (x == basic_block_end[i])
2904 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
2906 if ((bb = start[INSN_UID (tmp_rtx)]) >= 0)
2908 fprintf (outf, ";; Start of basic block %d, registers live:",
2911 EXECUTE_IF_SET_IN_REG_SET (basic_block_live_at_start[bb], 0, i,
2913 fprintf (outf, " %d", i);
2914 if (i < FIRST_PSEUDO_REGISTER)
2915 fprintf (outf, " [%s]",
2921 if (in_bb_p[ INSN_UID(tmp_rtx)] == NOT_IN_BB
2922 && GET_CODE (tmp_rtx) != NOTE
2923 && GET_CODE (tmp_rtx) != BARRIER)
2924 fprintf (outf, ";; Insn is not within a basic block\n");
2925 else if (in_bb_p[ INSN_UID(tmp_rtx)] == IN_MULTIPLE_BB)
2926 fprintf (outf, ";; Insn is in multiple basic blocks\n");
2928 print_rtl_single (outf, tmp_rtx);
2930 if ((bb = end[INSN_UID (tmp_rtx)]) >= 0)
2931 fprintf (outf, ";; End of basic block %d\n", bb);