1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 88, 92, 93, 94, 1995 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, 675 Mass Ave, Cambridge, MA 02139, USA. */
21 /* This file contains the data flow analysis pass of the compiler.
22 It computes data flow information
23 which tells combine_instructions which insns to consider combining
24 and controls register allocation.
26 Additional data flow information that is too bulky to record
27 is generated during the analysis, and is used at that time to
28 create autoincrement and autodecrement addressing.
30 The first step is dividing the function into basic blocks.
31 find_basic_blocks does this. Then life_analysis determines
32 where each register is live and where it is dead.
34 ** find_basic_blocks **
36 find_basic_blocks divides the current function's rtl
37 into basic blocks. It records the beginnings and ends of the
38 basic blocks in the vectors basic_block_head and basic_block_end,
39 and the number of blocks in n_basic_blocks.
41 find_basic_blocks also finds any unreachable loops
46 life_analysis is called immediately after find_basic_blocks.
47 It uses the basic block information to determine where each
48 hard or pseudo register is live.
50 ** live-register info **
52 The information about where each register is live is in two parts:
53 the REG_NOTES of insns, and the vector basic_block_live_at_start.
55 basic_block_live_at_start has an element for each basic block,
56 and the element is a bit-vector with a bit for each hard or pseudo
57 register. The bit is 1 if the register is live at the beginning
60 Two types of elements can be added to an insn's REG_NOTES.
61 A REG_DEAD note is added to an insn's REG_NOTES for any register
62 that meets both of two conditions: The value in the register is not
63 needed in subsequent insns and the insn does not replace the value in
64 the register (in the case of multi-word hard registers, the value in
65 each register must be replaced by the insn to avoid a REG_DEAD note).
67 In the vast majority of cases, an object in a REG_DEAD note will be
68 used somewhere in the insn. The (rare) exception to this is if an
69 insn uses a multi-word hard register and only some of the registers are
70 needed in subsequent insns. In that case, REG_DEAD notes will be
71 provided for those hard registers that are not subsequently needed.
72 Partial REG_DEAD notes of this type do not occur when an insn sets
73 only some of the hard registers used in such a multi-word operand;
74 omitting REG_DEAD notes for objects stored in an insn is optional and
75 the desire to do so does not justify the complexity of the partial
78 REG_UNUSED notes are added for each register that is set by the insn
79 but is unused subsequently (if every register set by the insn is unused
80 and the insn does not reference memory or have some other side-effect,
81 the insn is deleted instead). If only part of a multi-word hard
82 register is used in a subsequent insn, REG_UNUSED notes are made for
83 the parts that will not be used.
85 To determine which registers are live after any insn, one can
86 start from the beginning of the basic block and scan insns, noting
87 which registers are set by each insn and which die there.
89 ** Other actions of life_analysis **
91 life_analysis sets up the LOG_LINKS fields of insns because the
92 information needed to do so is readily available.
94 life_analysis deletes insns whose only effect is to store a value
97 life_analysis notices cases where a reference to a register as
98 a memory address can be combined with a preceding or following
99 incrementation or decrementation of the register. The separate
100 instruction to increment or decrement is deleted and the address
101 is changed to a POST_INC or similar rtx.
103 Each time an incrementing or decrementing address is created,
104 a REG_INC element is added to the insn's REG_NOTES list.
106 life_analysis fills in certain vectors containing information about
107 register usage: reg_n_refs, reg_n_deaths, reg_n_sets, reg_live_length,
108 reg_n_calls_crosses and reg_basic_block. */
113 #include "basic-block.h"
114 #include "insn-config.h"
116 #include "hard-reg-set.h"
121 #define obstack_chunk_alloc xmalloc
122 #define obstack_chunk_free free
124 /* List of labels that must never be deleted. */
125 extern rtx forced_labels;
127 /* Get the basic block number of an insn.
128 This info should not be expected to remain available
129 after the end of life_analysis. */
131 /* This is the limit of the allocated space in the following two arrays. */
133 static int max_uid_for_flow;
135 #define BLOCK_NUM(INSN) uid_block_number[INSN_UID (INSN)]
137 /* This is where the BLOCK_NUM values are really stored.
138 This is set up by find_basic_blocks and used there and in life_analysis,
141 static int *uid_block_number;
143 /* INSN_VOLATILE (insn) is 1 if the insn refers to anything volatile. */
145 #define INSN_VOLATILE(INSN) uid_volatile[INSN_UID (INSN)]
146 static char *uid_volatile;
148 /* Number of basic blocks in the current function. */
152 /* Maximum register number used in this function, plus one. */
156 /* Maximum number of SCRATCH rtx's used in any basic block of this function. */
160 /* Number of SCRATCH rtx's in the current block. */
162 static int num_scratch;
164 /* Indexed by n, gives number of basic block that (REG n) is used in.
165 If the value is REG_BLOCK_GLOBAL (-2),
166 it means (REG n) is used in more than one basic block.
167 REG_BLOCK_UNKNOWN (-1) means it hasn't been seen yet so we don't know.
168 This information remains valid for the rest of the compilation
169 of the current function; it is used to control register allocation. */
171 int *reg_basic_block;
173 /* Indexed by n, gives number of times (REG n) is used or set, each
174 weighted by its loop-depth.
175 This information remains valid for the rest of the compilation
176 of the current function; it is used to control register allocation. */
180 /* Indexed by N; says whether a psuedo register N was ever used
181 within a SUBREG that changes the size of the reg. Some machines prohibit
182 such objects to be in certain (usually floating-point) registers. */
184 char *reg_changes_size;
186 /* Indexed by N, gives number of places register N dies.
187 This information remains valid for the rest of the compilation
188 of the current function; it is used to control register allocation. */
192 /* Indexed by N, gives 1 if that reg is live across any CALL_INSNs.
193 This information remains valid for the rest of the compilation
194 of the current function; it is used to control register allocation. */
196 int *reg_n_calls_crossed;
198 /* Total number of instructions at which (REG n) is live.
199 The larger this is, the less priority (REG n) gets for
200 allocation in a real register.
201 This information remains valid for the rest of the compilation
202 of the current function; it is used to control register allocation.
204 local-alloc.c may alter this number to change the priority.
206 Negative values are special.
207 -1 is used to mark a pseudo reg which has a constant or memory equivalent
208 and is used infrequently enough that it should not get a hard register.
209 -2 is used to mark a pseudo reg for a parameter, when a frame pointer
210 is not required. global.c makes an allocno for this but does
211 not try to assign a hard register to it. */
213 int *reg_live_length;
215 /* Element N is the next insn that uses (hard or pseudo) register number N
216 within the current basic block; or zero, if there is no such insn.
217 This is valid only during the final backward scan in propagate_block. */
219 static rtx *reg_next_use;
221 /* Size of a regset for the current function,
222 in (1) bytes and (2) elements. */
227 /* Element N is first insn in basic block N.
228 This info lasts until we finish compiling the function. */
230 rtx *basic_block_head;
232 /* Element N is last insn in basic block N.
233 This info lasts until we finish compiling the function. */
235 rtx *basic_block_end;
237 /* Element N is a regset describing the registers live
238 at the start of basic block N.
239 This info lasts until we finish compiling the function. */
241 regset *basic_block_live_at_start;
243 /* Regset of regs live when calls to `setjmp'-like functions happen. */
245 regset regs_live_at_setjmp;
247 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
248 that have to go in the same hard reg.
249 The first two regs in the list are a pair, and the next two
250 are another pair, etc. */
253 /* Element N is nonzero if control can drop into basic block N
254 from the preceding basic block. Freed after life_analysis. */
256 static char *basic_block_drops_in;
258 /* Element N is depth within loops of the last insn in basic block number N.
259 Freed after life_analysis. */
261 static short *basic_block_loop_depth;
263 /* Element N nonzero if basic block N can actually be reached.
264 Vector exists only during find_basic_blocks. */
266 static char *block_live_static;
268 /* Depth within loops of basic block being scanned for lifetime analysis,
269 plus one. This is the weight attached to references to registers. */
271 static int loop_depth;
273 /* During propagate_block, this is non-zero if the value of CC0 is live. */
277 /* During propagate_block, this contains the last MEM stored into. It
278 is used to eliminate consecutive stores to the same location. */
280 static rtx last_mem_set;
282 /* Set of registers that may be eliminable. These are handled specially
283 in updating regs_ever_live. */
285 static HARD_REG_SET elim_reg_set;
287 /* Forward declarations */
288 static void find_basic_blocks PROTO((rtx, rtx));
289 static int uses_reg_or_mem PROTO((rtx));
290 static void mark_label_ref PROTO((rtx, rtx, int));
291 static void life_analysis PROTO((rtx, int));
292 void allocate_for_life_analysis PROTO((void));
293 static void init_regset_vector PROTO((regset *, regset, int, int));
294 static void propagate_block PROTO((regset, rtx, rtx, int,
296 static rtx flow_delete_insn PROTO((rtx));
297 static int insn_dead_p PROTO((rtx, regset, int));
298 static int libcall_dead_p PROTO((rtx, regset, rtx, rtx));
299 static void mark_set_regs PROTO((regset, regset, rtx,
301 static void mark_set_1 PROTO((regset, regset, rtx,
303 static void find_auto_inc PROTO((regset, rtx, rtx));
304 static void mark_used_regs PROTO((regset, regset, rtx, int, rtx));
305 static int try_pre_increment_1 PROTO((rtx));
306 static int try_pre_increment PROTO((rtx, rtx, HOST_WIDE_INT));
307 static rtx find_use_as_address PROTO((rtx, rtx, HOST_WIDE_INT));
308 void dump_flow_info PROTO((FILE *));
310 /* Find basic blocks of the current function and perform data flow analysis.
311 F is the first insn of the function and NREGS the number of register numbers
315 flow_analysis (f, nregs, file)
322 rtx nonlocal_label_list = nonlocal_label_rtx_list ();
324 #ifdef ELIMINABLE_REGS
325 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
328 /* Record which registers will be eliminated. We use this in
331 CLEAR_HARD_REG_SET (elim_reg_set);
333 #ifdef ELIMINABLE_REGS
334 for (i = 0; i < sizeof eliminables / sizeof eliminables[0]; i++)
335 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
337 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
340 /* Count the basic blocks. Also find maximum insn uid value used. */
343 register RTX_CODE prev_code = JUMP_INSN;
344 register RTX_CODE code;
346 max_uid_for_flow = 0;
348 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
350 code = GET_CODE (insn);
351 if (INSN_UID (insn) > max_uid_for_flow)
352 max_uid_for_flow = INSN_UID (insn);
353 if (code == CODE_LABEL
354 || (GET_RTX_CLASS (code) == 'i'
355 && (prev_code == JUMP_INSN
356 || (prev_code == CALL_INSN
357 && nonlocal_label_list != 0)
358 || prev_code == BARRIER)))
366 /* Leave space for insns we make in some cases for auto-inc. These cases
367 are rare, so we don't need too much space. */
368 max_uid_for_flow += max_uid_for_flow / 10;
371 /* Allocate some tables that last till end of compiling this function
372 and some needed only in find_basic_blocks and life_analysis. */
375 basic_block_head = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
376 basic_block_end = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
377 basic_block_drops_in = (char *) alloca (n_basic_blocks);
378 basic_block_loop_depth = (short *) alloca (n_basic_blocks * sizeof (short));
380 = (int *) alloca ((max_uid_for_flow + 1) * sizeof (int));
381 uid_volatile = (char *) alloca (max_uid_for_flow + 1);
382 bzero (uid_volatile, max_uid_for_flow + 1);
384 find_basic_blocks (f, nonlocal_label_list);
385 life_analysis (f, nregs);
387 dump_flow_info (file);
389 basic_block_drops_in = 0;
390 uid_block_number = 0;
391 basic_block_loop_depth = 0;
394 /* Find all basic blocks of the function whose first insn is F.
395 Store the correct data in the tables that describe the basic blocks,
396 set up the chains of references for each CODE_LABEL, and
397 delete any entire basic blocks that cannot be reached.
399 NONLOCAL_LABEL_LIST is the same local variable from flow_analysis. */
402 find_basic_blocks (f, nonlocal_label_list)
403 rtx f, nonlocal_label_list;
407 register char *block_live = (char *) alloca (n_basic_blocks);
408 register char *block_marked = (char *) alloca (n_basic_blocks);
409 /* List of label_refs to all labels whose addresses are taken
411 rtx label_value_list;
413 enum rtx_code prev_code, code;
419 label_value_list = 0;
420 block_live_static = block_live;
421 bzero (block_live, n_basic_blocks);
422 bzero (block_marked, n_basic_blocks);
424 /* Initialize with just block 0 reachable and no blocks marked. */
425 if (n_basic_blocks > 0)
428 /* Initialize the ref chain of each label to 0. Record where all the
429 blocks start and end and their depth in loops. For each insn, record
430 the block it is in. Also mark as reachable any blocks headed by labels
431 that must not be deleted. */
433 for (insn = f, i = -1, prev_code = JUMP_INSN, depth = 1;
434 insn; insn = NEXT_INSN (insn))
436 code = GET_CODE (insn);
439 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
441 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
445 /* A basic block starts at label, or after something that can jump. */
446 else if (code == CODE_LABEL
447 || (GET_RTX_CLASS (code) == 'i'
448 && (prev_code == JUMP_INSN
449 || (prev_code == CALL_INSN
450 && nonlocal_label_list != 0)
451 || prev_code == BARRIER)))
453 basic_block_head[++i] = insn;
454 basic_block_end[i] = insn;
455 basic_block_loop_depth[i] = depth;
457 if (code == CODE_LABEL)
459 LABEL_REFS (insn) = insn;
460 /* Any label that cannot be deleted
461 is considered to start a reachable block. */
462 if (LABEL_PRESERVE_P (insn))
467 else if (GET_RTX_CLASS (code) == 'i')
469 basic_block_end[i] = insn;
470 basic_block_loop_depth[i] = depth;
473 if (GET_RTX_CLASS (code) == 'i')
475 /* Make a list of all labels referred to other than by jumps. */
476 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
477 if (REG_NOTE_KIND (note) == REG_LABEL)
478 label_value_list = gen_rtx (EXPR_LIST, VOIDmode, XEXP (note, 0),
482 BLOCK_NUM (insn) = i;
488 if (i + 1 != n_basic_blocks)
491 /* Don't delete the labels (in this function)
492 that are referenced by non-jump instructions. */
494 for (x = label_value_list; x; x = XEXP (x, 1))
495 if (! LABEL_REF_NONLOCAL_P (x))
496 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
498 for (x = forced_labels; x; x = XEXP (x, 1))
499 if (! LABEL_REF_NONLOCAL_P (x))
500 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
502 /* Record which basic blocks control can drop in to. */
504 for (i = 0; i < n_basic_blocks; i++)
506 for (insn = PREV_INSN (basic_block_head[i]);
507 insn && GET_CODE (insn) == NOTE; insn = PREV_INSN (insn))
510 basic_block_drops_in[i] = insn && GET_CODE (insn) != BARRIER;
513 /* Now find which basic blocks can actually be reached
514 and put all jump insns' LABEL_REFS onto the ref-chains
515 of their target labels. */
517 if (n_basic_blocks > 0)
519 int something_marked = 1;
522 /* Find all indirect jump insns and mark them as possibly jumping to all
523 the labels whose addresses are explicitly used. This is because,
524 when there are computed gotos, we can't tell which labels they jump
525 to, of all the possibilities.
527 Tablejumps and casesi insns are OK and we can recognize them by
528 a (use (label_ref)). */
530 for (insn = f; insn; insn = NEXT_INSN (insn))
531 if (GET_CODE (insn) == JUMP_INSN)
533 rtx pat = PATTERN (insn);
534 int computed_jump = 0;
536 if (GET_CODE (pat) == PARALLEL)
538 int len = XVECLEN (pat, 0);
539 int has_use_labelref = 0;
541 for (i = len - 1; i >= 0; i--)
542 if (GET_CODE (XVECEXP (pat, 0, i)) == USE
543 && (GET_CODE (XEXP (XVECEXP (pat, 0, i), 0))
545 has_use_labelref = 1;
547 if (! has_use_labelref)
548 for (i = len - 1; i >= 0; i--)
549 if (GET_CODE (XVECEXP (pat, 0, i)) == SET
550 && SET_DEST (XVECEXP (pat, 0, i)) == pc_rtx
551 && uses_reg_or_mem (SET_SRC (XVECEXP (pat, 0, i))))
554 else if (GET_CODE (pat) == SET
555 && SET_DEST (pat) == pc_rtx
556 && uses_reg_or_mem (SET_SRC (pat)))
561 for (x = label_value_list; x; x = XEXP (x, 1))
562 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
565 for (x = forced_labels; x; x = XEXP (x, 1))
566 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
571 /* Find all call insns and mark them as possibly jumping
572 to all the nonlocal goto handler labels. */
574 for (insn = f; insn; insn = NEXT_INSN (insn))
575 if (GET_CODE (insn) == CALL_INSN)
577 for (x = nonlocal_label_list; x; x = XEXP (x, 1))
578 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
581 /* ??? This could be made smarter:
582 in some cases it's possible to tell that certain
583 calls will not do a nonlocal goto.
585 For example, if the nested functions that do the
586 nonlocal gotos do not have their addresses taken, then
587 only calls to those functions or to other nested
588 functions that use them could possibly do nonlocal
592 /* Pass over all blocks, marking each block that is reachable
593 and has not yet been marked.
594 Keep doing this until, in one pass, no blocks have been marked.
595 Then blocks_live and blocks_marked are identical and correct.
596 In addition, all jumps actually reachable have been marked. */
598 while (something_marked)
600 something_marked = 0;
601 for (i = 0; i < n_basic_blocks; i++)
602 if (block_live[i] && !block_marked[i])
605 something_marked = 1;
606 if (i + 1 < n_basic_blocks && basic_block_drops_in[i + 1])
607 block_live[i + 1] = 1;
608 insn = basic_block_end[i];
609 if (GET_CODE (insn) == JUMP_INSN)
610 mark_label_ref (PATTERN (insn), insn, 0);
614 /* ??? See if we have a "live" basic block that is not reachable.
615 This can happen if it is headed by a label that is preserved or
616 in one of the label lists, but no call or computed jump is in
617 the loop. It's not clear if we can delete the block or not,
618 but don't for now. However, we will mess up register status if
619 it remains unreachable, so add a fake reachability from the
622 for (i = 1; i < n_basic_blocks; i++)
623 if (block_live[i] && ! basic_block_drops_in[i]
624 && GET_CODE (basic_block_head[i]) == CODE_LABEL
625 && LABEL_REFS (basic_block_head[i]) == basic_block_head[i])
626 basic_block_drops_in[i] = 1;
628 /* Now delete the code for any basic blocks that can't be reached.
629 They can occur because jump_optimize does not recognize
630 unreachable loops as unreachable. */
633 for (i = 0; i < n_basic_blocks; i++)
638 /* Delete the insns in a (non-live) block. We physically delete
639 every non-note insn except the start and end (so
640 basic_block_head/end needn't be updated), we turn the latter
641 into NOTE_INSN_DELETED notes.
642 We use to "delete" the insns by turning them into notes, but
643 we may be deleting lots of insns that subsequent passes would
644 otherwise have to process. Secondly, lots of deleted blocks in
645 a row can really slow down propagate_block since it will
646 otherwise process insn-turned-notes multiple times when it
647 looks for loop begin/end notes. */
648 if (basic_block_head[i] != basic_block_end[i])
650 /* It would be quicker to delete all of these with a single
651 unchaining, rather than one at a time, but we need to keep
653 insn = NEXT_INSN (basic_block_head[i]);
654 while (insn != basic_block_end[i])
656 if (GET_CODE (insn) == BARRIER)
658 else if (GET_CODE (insn) != NOTE)
659 insn = flow_delete_insn (insn);
661 insn = NEXT_INSN (insn);
664 insn = basic_block_head[i];
665 if (GET_CODE (insn) != NOTE)
667 /* Turn the head into a deleted insn note. */
668 if (GET_CODE (insn) == BARRIER)
670 PUT_CODE (insn, NOTE);
671 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
672 NOTE_SOURCE_FILE (insn) = 0;
674 insn = basic_block_end[i];
675 if (GET_CODE (insn) != NOTE)
677 /* Turn the tail into a deleted insn note. */
678 if (GET_CODE (insn) == BARRIER)
680 PUT_CODE (insn, NOTE);
681 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
682 NOTE_SOURCE_FILE (insn) = 0;
684 /* BARRIERs are between basic blocks, not part of one.
685 Delete a BARRIER if the preceding jump is deleted.
686 We cannot alter a BARRIER into a NOTE
687 because it is too short; but we can really delete
688 it because it is not part of a basic block. */
689 if (NEXT_INSN (insn) != 0
690 && GET_CODE (NEXT_INSN (insn)) == BARRIER)
691 delete_insn (NEXT_INSN (insn));
693 /* Each time we delete some basic blocks,
694 see if there is a jump around them that is
695 being turned into a no-op. If so, delete it. */
697 if (block_live[i - 1])
700 for (j = i + 1; j < n_basic_blocks; j++)
704 insn = basic_block_end[i - 1];
705 if (GET_CODE (insn) == JUMP_INSN
706 /* An unconditional jump is the only possibility
707 we must check for, since a conditional one
708 would make these blocks live. */
709 && simplejump_p (insn)
710 && (label = XEXP (SET_SRC (PATTERN (insn)), 0), 1)
711 && INSN_UID (label) != 0
712 && BLOCK_NUM (label) == j)
714 PUT_CODE (insn, NOTE);
715 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
716 NOTE_SOURCE_FILE (insn) = 0;
717 if (GET_CODE (NEXT_INSN (insn)) != BARRIER)
719 delete_insn (NEXT_INSN (insn));
726 /* There are pathalogical cases where one function calling hundreds of
727 nested inline functions can generate lots and lots of unreachable
728 blocks that jump can't delete. Since we don't use sparse matrices
729 a lot of memory will be needed to compile such functions.
730 Implementing sparse matrices is a fair bit of work and it is not
731 clear that they win more than they lose (we don't want to
732 unnecessarily slow down compilation of normal code). By making
733 another pass for the pathalogical case, we can greatly speed up
734 their compilation without hurting normal code. This works because
735 all the insns in the unreachable blocks have either been deleted or
737 Note that we're talking about reducing memory usage by 10's of
738 megabytes and reducing compilation time by several minutes. */
739 /* ??? The choice of when to make another pass is a bit arbitrary,
740 and was derived from empirical data. */
745 n_basic_blocks -= deleted;
751 /* Subroutines of find_basic_blocks. */
753 /* Return 1 if X contain a REG or MEM that is not in the constant pool. */
759 enum rtx_code code = GET_CODE (x);
765 && ! (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
766 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))))
769 fmt = GET_RTX_FORMAT (code);
770 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
773 && uses_reg_or_mem (XEXP (x, i)))
777 for (j = 0; j < XVECLEN (x, i); j++)
778 if (uses_reg_or_mem (XVECEXP (x, i, j)))
785 /* Check expression X for label references;
786 if one is found, add INSN to the label's chain of references.
788 CHECKDUP means check for and avoid creating duplicate references
789 from the same insn. Such duplicates do no serious harm but
790 can slow life analysis. CHECKDUP is set only when duplicates
794 mark_label_ref (x, insn, checkdup)
798 register RTX_CODE code;
802 /* We can be called with NULL when scanning label_value_list. */
807 if (code == LABEL_REF)
809 register rtx label = XEXP (x, 0);
811 if (GET_CODE (label) != CODE_LABEL)
813 /* If the label was never emitted, this insn is junk,
814 but avoid a crash trying to refer to BLOCK_NUM (label).
815 This can happen as a result of a syntax error
816 and a diagnostic has already been printed. */
817 if (INSN_UID (label) == 0)
819 CONTAINING_INSN (x) = insn;
820 /* if CHECKDUP is set, check for duplicate ref from same insn
823 for (y = LABEL_REFS (label); y != label; y = LABEL_NEXTREF (y))
824 if (CONTAINING_INSN (y) == insn)
826 LABEL_NEXTREF (x) = LABEL_REFS (label);
827 LABEL_REFS (label) = x;
828 block_live_static[BLOCK_NUM (label)] = 1;
832 fmt = GET_RTX_FORMAT (code);
833 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
836 mark_label_ref (XEXP (x, i), insn, 0);
840 for (j = 0; j < XVECLEN (x, i); j++)
841 mark_label_ref (XVECEXP (x, i, j), insn, 1);
846 /* Delete INSN by patching it out.
847 Return the next insn. */
850 flow_delete_insn (insn)
853 /* ??? For the moment we assume we don't have to watch for NULLs here
854 since the start/end of basic blocks aren't deleted like this. */
855 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
856 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
857 return NEXT_INSN (insn);
860 /* Determine which registers are live at the start of each
861 basic block of the function whose first insn is F.
862 NREGS is the number of registers used in F.
863 We allocate the vector basic_block_live_at_start
864 and the regsets that it points to, and fill them with the data.
865 regset_size and regset_bytes are also set here. */
868 life_analysis (f, nregs)
875 /* For each basic block, a bitmask of regs
876 live on exit from the block. */
877 regset *basic_block_live_at_end;
878 /* For each basic block, a bitmask of regs
879 live on entry to a successor-block of this block.
880 If this does not match basic_block_live_at_end,
881 that must be updated, and the block must be rescanned. */
882 regset *basic_block_new_live_at_end;
883 /* For each basic block, a bitmask of regs
884 whose liveness at the end of the basic block
885 can make a difference in which regs are live on entry to the block.
886 These are the regs that are set within the basic block,
887 possibly excluding those that are used after they are set. */
888 regset *basic_block_significant;
892 struct obstack flow_obstack;
894 gcc_obstack_init (&flow_obstack);
898 bzero (regs_ever_live, sizeof regs_ever_live);
900 /* Allocate and zero out many data structures
901 that will record the data from lifetime analysis. */
903 allocate_for_life_analysis ();
905 reg_next_use = (rtx *) alloca (nregs * sizeof (rtx));
906 bzero ((char *) reg_next_use, nregs * sizeof (rtx));
908 /* Set up several regset-vectors used internally within this function.
909 Their meanings are documented above, with their declarations. */
911 basic_block_live_at_end
912 = (regset *) alloca (n_basic_blocks * sizeof (regset));
914 /* Don't use alloca since that leads to a crash rather than an error message
915 if there isn't enough space.
916 Don't use oballoc since we may need to allocate other things during
917 this function on the temporary obstack. */
918 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
919 bzero ((char *) tem, n_basic_blocks * regset_bytes);
920 init_regset_vector (basic_block_live_at_end, tem,
921 n_basic_blocks, regset_bytes);
923 basic_block_new_live_at_end
924 = (regset *) alloca (n_basic_blocks * sizeof (regset));
925 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
926 bzero ((char *) tem, n_basic_blocks * regset_bytes);
927 init_regset_vector (basic_block_new_live_at_end, tem,
928 n_basic_blocks, regset_bytes);
930 basic_block_significant
931 = (regset *) alloca (n_basic_blocks * sizeof (regset));
932 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
933 bzero ((char *) tem, n_basic_blocks * regset_bytes);
934 init_regset_vector (basic_block_significant, tem,
935 n_basic_blocks, regset_bytes);
937 /* Record which insns refer to any volatile memory
938 or for any reason can't be deleted just because they are dead stores.
939 Also, delete any insns that copy a register to itself. */
941 for (insn = f; insn; insn = NEXT_INSN (insn))
943 enum rtx_code code1 = GET_CODE (insn);
944 if (code1 == CALL_INSN)
945 INSN_VOLATILE (insn) = 1;
946 else if (code1 == INSN || code1 == JUMP_INSN)
948 /* Delete (in effect) any obvious no-op moves. */
949 if (GET_CODE (PATTERN (insn)) == SET
950 && GET_CODE (SET_DEST (PATTERN (insn))) == REG
951 && GET_CODE (SET_SRC (PATTERN (insn))) == REG
952 && REGNO (SET_DEST (PATTERN (insn))) ==
953 REGNO (SET_SRC (PATTERN (insn)))
954 /* Insns carrying these notes are useful later on. */
955 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
957 PUT_CODE (insn, NOTE);
958 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
959 NOTE_SOURCE_FILE (insn) = 0;
961 else if (GET_CODE (PATTERN (insn)) == PARALLEL)
963 /* If nothing but SETs of registers to themselves,
964 this insn can also be deleted. */
965 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
967 rtx tem = XVECEXP (PATTERN (insn), 0, i);
969 if (GET_CODE (tem) == USE
970 || GET_CODE (tem) == CLOBBER)
973 if (GET_CODE (tem) != SET
974 || GET_CODE (SET_DEST (tem)) != REG
975 || GET_CODE (SET_SRC (tem)) != REG
976 || REGNO (SET_DEST (tem)) != REGNO (SET_SRC (tem)))
980 if (i == XVECLEN (PATTERN (insn), 0)
981 /* Insns carrying these notes are useful later on. */
982 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
984 PUT_CODE (insn, NOTE);
985 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
986 NOTE_SOURCE_FILE (insn) = 0;
989 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
991 else if (GET_CODE (PATTERN (insn)) != USE)
992 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
993 /* A SET that makes space on the stack cannot be dead.
994 (Such SETs occur only for allocating variable-size data,
995 so they will always have a PLUS or MINUS according to the
996 direction of stack growth.)
997 Even if this function never uses this stack pointer value,
998 signal handlers do! */
999 else if (code1 == INSN && GET_CODE (PATTERN (insn)) == SET
1000 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1001 #ifdef STACK_GROWS_DOWNWARD
1002 && GET_CODE (SET_SRC (PATTERN (insn))) == MINUS
1004 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1006 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx)
1007 INSN_VOLATILE (insn) = 1;
1011 if (n_basic_blocks > 0)
1012 #ifdef EXIT_IGNORE_STACK
1013 if (! EXIT_IGNORE_STACK
1014 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
1017 /* If exiting needs the right stack value,
1018 consider the stack pointer live at the end of the function. */
1019 basic_block_live_at_end[n_basic_blocks - 1]
1020 [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
1021 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
1022 basic_block_new_live_at_end[n_basic_blocks - 1]
1023 [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
1024 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
1027 /* Mark the frame pointer is needed at the end of the function. If
1028 we end up eliminating it, it will be removed from the live list
1029 of each basic block by reload. */
1031 if (n_basic_blocks > 0)
1033 basic_block_live_at_end[n_basic_blocks - 1]
1034 [FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
1035 |= (REGSET_ELT_TYPE) 1 << (FRAME_POINTER_REGNUM % REGSET_ELT_BITS);
1036 basic_block_new_live_at_end[n_basic_blocks - 1]
1037 [FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
1038 |= (REGSET_ELT_TYPE) 1 << (FRAME_POINTER_REGNUM % REGSET_ELT_BITS);
1039 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1040 /* If they are different, also mark the hard frame pointer as live */
1041 basic_block_live_at_end[n_basic_blocks - 1]
1042 [HARD_FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
1043 |= (REGSET_ELT_TYPE) 1 << (HARD_FRAME_POINTER_REGNUM
1045 basic_block_new_live_at_end[n_basic_blocks - 1]
1046 [HARD_FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
1047 |= (REGSET_ELT_TYPE) 1 << (HARD_FRAME_POINTER_REGNUM
1052 /* Mark all global registers as being live at the end of the function
1053 since they may be referenced by our caller. */
1055 if (n_basic_blocks > 0)
1056 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1059 basic_block_live_at_end[n_basic_blocks - 1]
1060 [i / REGSET_ELT_BITS]
1061 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
1062 basic_block_new_live_at_end[n_basic_blocks - 1]
1063 [i / REGSET_ELT_BITS]
1064 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
1067 /* Propagate life info through the basic blocks
1068 around the graph of basic blocks.
1070 This is a relaxation process: each time a new register
1071 is live at the end of the basic block, we must scan the block
1072 to determine which registers are, as a consequence, live at the beginning
1073 of that block. These registers must then be marked live at the ends
1074 of all the blocks that can transfer control to that block.
1075 The process continues until it reaches a fixed point. */
1082 for (i = n_basic_blocks - 1; i >= 0; i--)
1084 int consider = first_pass;
1085 int must_rescan = first_pass;
1090 /* Set CONSIDER if this block needs thinking about at all
1091 (that is, if the regs live now at the end of it
1092 are not the same as were live at the end of it when
1093 we last thought about it).
1094 Set must_rescan if it needs to be thought about
1095 instruction by instruction (that is, if any additional
1096 reg that is live at the end now but was not live there before
1097 is one of the significant regs of this basic block). */
1099 for (j = 0; j < regset_size; j++)
1101 register REGSET_ELT_TYPE x
1102 = (basic_block_new_live_at_end[i][j]
1103 & ~basic_block_live_at_end[i][j]);
1106 if (x & basic_block_significant[i][j])
1118 /* The live_at_start of this block may be changing,
1119 so another pass will be required after this one. */
1124 /* No complete rescan needed;
1125 just record those variables newly known live at end
1126 as live at start as well. */
1127 for (j = 0; j < regset_size; j++)
1129 register REGSET_ELT_TYPE x
1130 = (basic_block_new_live_at_end[i][j]
1131 & ~basic_block_live_at_end[i][j]);
1132 basic_block_live_at_start[i][j] |= x;
1133 basic_block_live_at_end[i][j] |= x;
1138 /* Update the basic_block_live_at_start
1139 by propagation backwards through the block. */
1140 bcopy ((char *) basic_block_new_live_at_end[i],
1141 (char *) basic_block_live_at_end[i], regset_bytes);
1142 bcopy ((char *) basic_block_live_at_end[i],
1143 (char *) basic_block_live_at_start[i], regset_bytes);
1144 propagate_block (basic_block_live_at_start[i],
1145 basic_block_head[i], basic_block_end[i], 0,
1146 first_pass ? basic_block_significant[i]
1152 register rtx jump, head;
1154 /* Update the basic_block_new_live_at_end's of the block
1155 that falls through into this one (if any). */
1156 head = basic_block_head[i];
1157 if (basic_block_drops_in[i])
1160 for (j = 0; j < regset_size; j++)
1161 basic_block_new_live_at_end[i-1][j]
1162 |= basic_block_live_at_start[i][j];
1165 /* Update the basic_block_new_live_at_end's of
1166 all the blocks that jump to this one. */
1167 if (GET_CODE (head) == CODE_LABEL)
1168 for (jump = LABEL_REFS (head);
1170 jump = LABEL_NEXTREF (jump))
1172 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
1174 for (j = 0; j < regset_size; j++)
1175 basic_block_new_live_at_end[from_block][j]
1176 |= basic_block_live_at_start[i][j];
1186 /* The only pseudos that are live at the beginning of the function are
1187 those that were not set anywhere in the function. local-alloc doesn't
1188 know how to handle these correctly, so mark them as not local to any
1191 if (n_basic_blocks > 0)
1192 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
1193 if (basic_block_live_at_start[0][i / REGSET_ELT_BITS]
1194 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
1195 reg_basic_block[i] = REG_BLOCK_GLOBAL;
1197 /* Now the life information is accurate.
1198 Make one more pass over each basic block
1199 to delete dead stores, create autoincrement addressing
1200 and record how many times each register is used, is set, or dies.
1202 To save time, we operate directly in basic_block_live_at_end[i],
1203 thus destroying it (in fact, converting it into a copy of
1204 basic_block_live_at_start[i]). This is ok now because
1205 basic_block_live_at_end[i] is no longer used past this point. */
1209 for (i = 0; i < n_basic_blocks; i++)
1211 propagate_block (basic_block_live_at_end[i],
1212 basic_block_head[i], basic_block_end[i], 1,
1220 /* Something live during a setjmp should not be put in a register
1221 on certain machines which restore regs from stack frames
1222 rather than from the jmpbuf.
1223 But we don't need to do this for the user's variables, since
1224 ANSI says only volatile variables need this. */
1225 #ifdef LONGJMP_RESTORE_FROM_STACK
1226 for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1227 if (regs_live_at_setjmp[i / REGSET_ELT_BITS]
1228 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS))
1229 && regno_reg_rtx[i] != 0 && ! REG_USERVAR_P (regno_reg_rtx[i]))
1231 reg_live_length[i] = -1;
1232 reg_basic_block[i] = -1;
1237 /* We have a problem with any pseudoreg that
1238 lives across the setjmp. ANSI says that if a
1239 user variable does not change in value
1240 between the setjmp and the longjmp, then the longjmp preserves it.
1241 This includes longjmp from a place where the pseudo appears dead.
1242 (In principle, the value still exists if it is in scope.)
1243 If the pseudo goes in a hard reg, some other value may occupy
1244 that hard reg where this pseudo is dead, thus clobbering the pseudo.
1245 Conclusion: such a pseudo must not go in a hard reg. */
1246 for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1247 if ((regs_live_at_setjmp[i / REGSET_ELT_BITS]
1248 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
1249 && regno_reg_rtx[i] != 0)
1251 reg_live_length[i] = -1;
1252 reg_basic_block[i] = -1;
1255 obstack_free (&flow_obstack, NULL_PTR);
1258 /* Subroutines of life analysis. */
1260 /* Allocate the permanent data structures that represent the results
1261 of life analysis. Not static since used also for stupid life analysis. */
1264 allocate_for_life_analysis ()
1267 register regset tem;
1269 regset_size = ((max_regno + REGSET_ELT_BITS - 1) / REGSET_ELT_BITS);
1270 regset_bytes = regset_size * sizeof (*(regset)0);
1272 reg_n_refs = (int *) oballoc (max_regno * sizeof (int));
1273 bzero ((char *) reg_n_refs, max_regno * sizeof (int));
1275 reg_n_sets = (short *) oballoc (max_regno * sizeof (short));
1276 bzero ((char *) reg_n_sets, max_regno * sizeof (short));
1278 reg_n_deaths = (short *) oballoc (max_regno * sizeof (short));
1279 bzero ((char *) reg_n_deaths, max_regno * sizeof (short));
1281 reg_changes_size = (char *) oballoc (max_regno * sizeof (char));
1282 bzero (reg_changes_size, max_regno * sizeof (char));;
1284 reg_live_length = (int *) oballoc (max_regno * sizeof (int));
1285 bzero ((char *) reg_live_length, max_regno * sizeof (int));
1287 reg_n_calls_crossed = (int *) oballoc (max_regno * sizeof (int));
1288 bzero ((char *) reg_n_calls_crossed, max_regno * sizeof (int));
1290 reg_basic_block = (int *) oballoc (max_regno * sizeof (int));
1291 for (i = 0; i < max_regno; i++)
1292 reg_basic_block[i] = REG_BLOCK_UNKNOWN;
1294 basic_block_live_at_start
1295 = (regset *) oballoc (n_basic_blocks * sizeof (regset));
1296 tem = (regset) oballoc (n_basic_blocks * regset_bytes);
1297 bzero ((char *) tem, n_basic_blocks * regset_bytes);
1298 init_regset_vector (basic_block_live_at_start, tem,
1299 n_basic_blocks, regset_bytes);
1301 regs_live_at_setjmp = (regset) oballoc (regset_bytes);
1302 bzero ((char *) regs_live_at_setjmp, regset_bytes);
1305 /* Make each element of VECTOR point at a regset,
1306 taking the space for all those regsets from SPACE.
1307 SPACE is of type regset, but it is really as long as NELTS regsets.
1308 BYTES_PER_ELT is the number of bytes in one regset. */
1311 init_regset_vector (vector, space, nelts, bytes_per_elt)
1318 register regset p = space;
1320 for (i = 0; i < nelts; i++)
1323 p += bytes_per_elt / sizeof (*p);
1327 /* Compute the registers live at the beginning of a basic block
1328 from those live at the end.
1330 When called, OLD contains those live at the end.
1331 On return, it contains those live at the beginning.
1332 FIRST and LAST are the first and last insns of the basic block.
1334 FINAL is nonzero if we are doing the final pass which is not
1335 for computing the life info (since that has already been done)
1336 but for acting on it. On this pass, we delete dead stores,
1337 set up the logical links and dead-variables lists of instructions,
1338 and merge instructions for autoincrement and autodecrement addresses.
1340 SIGNIFICANT is nonzero only the first time for each basic block.
1341 If it is nonzero, it points to a regset in which we store
1342 a 1 for each register that is set within the block.
1344 BNUM is the number of the basic block. */
1347 propagate_block (old, first, last, final, significant, bnum)
1348 register regset old;
1360 /* The following variables are used only if FINAL is nonzero. */
1361 /* This vector gets one element for each reg that has been live
1362 at any point in the basic block that has been scanned so far.
1363 SOMETIMES_MAX says how many elements are in use so far.
1364 In each element, OFFSET is the byte-number within a regset
1365 for the register described by the element, and BIT is a mask
1366 for that register's bit within the byte. */
1367 register struct sometimes { short offset; short bit; } *regs_sometimes_live;
1368 int sometimes_max = 0;
1369 /* This regset has 1 for each reg that we have seen live so far.
1370 It and REGS_SOMETIMES_LIVE are updated together. */
1373 /* The loop depth may change in the middle of a basic block. Since we
1374 scan from end to beginning, we start with the depth at the end of the
1375 current basic block, and adjust as we pass ends and starts of loops. */
1376 loop_depth = basic_block_loop_depth[bnum];
1378 dead = (regset) alloca (regset_bytes);
1379 live = (regset) alloca (regset_bytes);
1384 /* Include any notes at the end of the block in the scan.
1385 This is in case the block ends with a call to setjmp. */
1387 while (NEXT_INSN (last) != 0 && GET_CODE (NEXT_INSN (last)) == NOTE)
1389 /* Look for loop boundaries, we are going forward here. */
1390 last = NEXT_INSN (last);
1391 if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_BEG)
1393 else if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_END)
1399 register int i, offset;
1400 REGSET_ELT_TYPE bit;
1403 maxlive = (regset) alloca (regset_bytes);
1404 bcopy ((char *) old, (char *) maxlive, regset_bytes);
1406 = (struct sometimes *) alloca (max_regno * sizeof (struct sometimes));
1408 /* Process the regs live at the end of the block.
1409 Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
1410 Also mark them as not local to any one basic block. */
1412 for (offset = 0, i = 0; offset < regset_size; offset++)
1413 for (bit = 1; bit; bit <<= 1, i++)
1417 if (old[offset] & bit)
1419 reg_basic_block[i] = REG_BLOCK_GLOBAL;
1420 regs_sometimes_live[sometimes_max].offset = offset;
1421 regs_sometimes_live[sometimes_max].bit = i % REGSET_ELT_BITS;
1427 /* Scan the block an insn at a time from end to beginning. */
1429 for (insn = last; ; insn = prev)
1431 prev = PREV_INSN (insn);
1433 if (GET_CODE (insn) == NOTE)
1435 /* Look for loop boundaries, remembering that we are going
1437 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1439 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1442 /* If we have LOOP_DEPTH == 0, there has been a bookkeeping error.
1443 Abort now rather than setting register status incorrectly. */
1444 if (loop_depth == 0)
1447 /* If this is a call to `setjmp' et al,
1448 warn if any non-volatile datum is live. */
1450 if (final && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
1453 for (i = 0; i < regset_size; i++)
1454 regs_live_at_setjmp[i] |= old[i];
1458 /* Update the life-status of regs for this insn.
1459 First DEAD gets which regs are set in this insn
1460 then LIVE gets which regs are used in this insn.
1461 Then the regs live before the insn
1462 are those live after, with DEAD regs turned off,
1463 and then LIVE regs turned on. */
1465 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
1468 rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1470 = (insn_dead_p (PATTERN (insn), old, 0)
1471 /* Don't delete something that refers to volatile storage! */
1472 && ! INSN_VOLATILE (insn));
1474 = (insn_is_dead && note != 0
1475 && libcall_dead_p (PATTERN (insn), old, note, insn));
1477 /* If an instruction consists of just dead store(s) on final pass,
1478 "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
1479 We could really delete it with delete_insn, but that
1480 can cause trouble for first or last insn in a basic block. */
1481 if (final && insn_is_dead)
1483 PUT_CODE (insn, NOTE);
1484 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
1485 NOTE_SOURCE_FILE (insn) = 0;
1487 /* CC0 is now known to be dead. Either this insn used it,
1488 in which case it doesn't anymore, or clobbered it,
1489 so the next insn can't use it. */
1492 /* If this insn is copying the return value from a library call,
1493 delete the entire library call. */
1494 if (libcall_is_dead)
1496 rtx first = XEXP (note, 0);
1498 while (INSN_DELETED_P (first))
1499 first = NEXT_INSN (first);
1504 NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED;
1505 NOTE_SOURCE_FILE (p) = 0;
1511 for (i = 0; i < regset_size; i++)
1513 dead[i] = 0; /* Faster than bzero here */
1514 live[i] = 0; /* since regset_size is usually small */
1517 /* See if this is an increment or decrement that can be
1518 merged into a following memory address. */
1521 register rtx x = PATTERN (insn);
1522 /* Does this instruction increment or decrement a register? */
1523 if (final && GET_CODE (x) == SET
1524 && GET_CODE (SET_DEST (x)) == REG
1525 && (GET_CODE (SET_SRC (x)) == PLUS
1526 || GET_CODE (SET_SRC (x)) == MINUS)
1527 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1528 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1529 /* Ok, look for a following memory ref we can combine with.
1530 If one is found, change the memory ref to a PRE_INC
1531 or PRE_DEC, cancel this insn, and return 1.
1532 Return 0 if nothing has been done. */
1533 && try_pre_increment_1 (insn))
1536 #endif /* AUTO_INC_DEC */
1538 /* If this is not the final pass, and this insn is copying the
1539 value of a library call and it's dead, don't scan the
1540 insns that perform the library call, so that the call's
1541 arguments are not marked live. */
1542 if (libcall_is_dead)
1544 /* Mark the dest reg as `significant'. */
1545 mark_set_regs (old, dead, PATTERN (insn), NULL_RTX, significant);
1547 insn = XEXP (note, 0);
1548 prev = PREV_INSN (insn);
1550 else if (GET_CODE (PATTERN (insn)) == SET
1551 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1552 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1553 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1554 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1555 /* We have an insn to pop a constant amount off the stack.
1556 (Such insns use PLUS regardless of the direction of the stack,
1557 and any insn to adjust the stack by a constant is always a pop.)
1558 These insns, if not dead stores, have no effect on life. */
1562 /* LIVE gets the regs used in INSN;
1563 DEAD gets those set by it. Dead insns don't make anything
1566 mark_set_regs (old, dead, PATTERN (insn),
1567 final ? insn : NULL_RTX, significant);
1569 /* If an insn doesn't use CC0, it becomes dead since we
1570 assume that every insn clobbers it. So show it dead here;
1571 mark_used_regs will set it live if it is referenced. */
1575 mark_used_regs (old, live, PATTERN (insn), final, insn);
1577 /* Sometimes we may have inserted something before INSN (such as
1578 a move) when we make an auto-inc. So ensure we will scan
1581 prev = PREV_INSN (insn);
1584 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1590 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1592 note = XEXP (note, 1))
1593 if (GET_CODE (XEXP (note, 0)) == USE)
1594 mark_used_regs (old, live, SET_DEST (XEXP (note, 0)),
1597 /* Each call clobbers all call-clobbered regs that are not
1598 global. Note that the function-value reg is a
1599 call-clobbered reg, and mark_set_regs has already had
1600 a chance to handle it. */
1602 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1603 if (call_used_regs[i] && ! global_regs[i])
1604 dead[i / REGSET_ELT_BITS]
1605 |= ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS));
1607 /* The stack ptr is used (honorarily) by a CALL insn. */
1608 live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
1609 |= ((REGSET_ELT_TYPE) 1
1610 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS));
1612 /* Calls may also reference any of the global registers,
1613 so they are made live. */
1614 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1616 mark_used_regs (old, live,
1617 gen_rtx (REG, reg_raw_mode[i], i),
1620 /* Calls also clobber memory. */
1624 /* Update OLD for the registers used or set. */
1625 for (i = 0; i < regset_size; i++)
1631 if (GET_CODE (insn) == CALL_INSN && final)
1633 /* Any regs live at the time of a call instruction
1634 must not go in a register clobbered by calls.
1635 Find all regs now live and record this for them. */
1637 register struct sometimes *p = regs_sometimes_live;
1639 for (i = 0; i < sometimes_max; i++, p++)
1640 if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
1641 reg_n_calls_crossed[p->offset * REGSET_ELT_BITS + p->bit]+= 1;
1645 /* On final pass, add any additional sometimes-live regs
1646 into MAXLIVE and REGS_SOMETIMES_LIVE.
1647 Also update counts of how many insns each reg is live at. */
1651 for (i = 0; i < regset_size; i++)
1653 register REGSET_ELT_TYPE diff = live[i] & ~maxlive[i];
1659 for (regno = 0; diff && regno < REGSET_ELT_BITS; regno++)
1660 if (diff & ((REGSET_ELT_TYPE) 1 << regno))
1662 regs_sometimes_live[sometimes_max].offset = i;
1663 regs_sometimes_live[sometimes_max].bit = regno;
1664 diff &= ~ ((REGSET_ELT_TYPE) 1 << regno);
1671 register struct sometimes *p = regs_sometimes_live;
1672 for (i = 0; i < sometimes_max; i++, p++)
1674 if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
1675 reg_live_length[p->offset * REGSET_ELT_BITS + p->bit]++;
1685 if (num_scratch > max_scratch)
1686 max_scratch = num_scratch;
1689 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1690 (SET expressions whose destinations are registers dead after the insn).
1691 NEEDED is the regset that says which regs are alive after the insn.
1693 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */
1696 insn_dead_p (x, needed, call_ok)
1701 register RTX_CODE code = GET_CODE (x);
1702 /* If setting something that's a reg or part of one,
1703 see if that register's altered value will be live. */
1707 register rtx r = SET_DEST (x);
1708 /* A SET that is a subroutine call cannot be dead. */
1709 if (! call_ok && GET_CODE (SET_SRC (x)) == CALL)
1713 if (GET_CODE (r) == CC0)
1717 if (GET_CODE (r) == MEM && last_mem_set && ! MEM_VOLATILE_P (r)
1718 && rtx_equal_p (r, last_mem_set))
1721 while (GET_CODE (r) == SUBREG
1722 || GET_CODE (r) == STRICT_LOW_PART
1723 || GET_CODE (r) == ZERO_EXTRACT
1724 || GET_CODE (r) == SIGN_EXTRACT)
1727 if (GET_CODE (r) == REG)
1729 register int regno = REGNO (r);
1730 register int offset = regno / REGSET_ELT_BITS;
1731 register REGSET_ELT_TYPE bit
1732 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
1734 /* Don't delete insns to set global regs. */
1735 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
1736 /* Make sure insns to set frame pointer aren't deleted. */
1737 || regno == FRAME_POINTER_REGNUM
1738 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1739 || regno == HARD_FRAME_POINTER_REGNUM
1741 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1742 /* Make sure insns to set arg pointer are never deleted
1743 (if the arg pointer isn't fixed, there will be a USE for
1744 it, so we can treat it normally). */
1745 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1747 || (needed[offset] & bit) != 0)
1750 /* If this is a hard register, verify that subsequent words are
1752 if (regno < FIRST_PSEUDO_REGISTER)
1754 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
1757 if ((needed[(regno + n) / REGSET_ELT_BITS]
1758 & ((REGSET_ELT_TYPE) 1
1759 << ((regno + n) % REGSET_ELT_BITS))) != 0)
1766 /* If performing several activities,
1767 insn is dead if each activity is individually dead.
1768 Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
1769 that's inside a PARALLEL doesn't make the insn worth keeping. */
1770 else if (code == PARALLEL)
1772 register int i = XVECLEN (x, 0);
1773 for (i--; i >= 0; i--)
1775 rtx elt = XVECEXP (x, 0, i);
1776 if (!insn_dead_p (elt, needed, call_ok)
1777 && GET_CODE (elt) != CLOBBER
1778 && GET_CODE (elt) != USE)
1783 /* We do not check CLOBBER or USE here.
1784 An insn consisting of just a CLOBBER or just a USE
1785 should not be deleted. */
1789 /* If X is the pattern of the last insn in a libcall, and assuming X is dead,
1790 return 1 if the entire library call is dead.
1791 This is true if X copies a register (hard or pseudo)
1792 and if the hard return reg of the call insn is dead.
1793 (The caller should have tested the destination of X already for death.)
1795 If this insn doesn't just copy a register, then we don't
1796 have an ordinary libcall. In that case, cse could not have
1797 managed to substitute the source for the dest later on,
1798 so we can assume the libcall is dead.
1800 NEEDED is the bit vector of pseudoregs live before this insn.
1801 NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
1804 libcall_dead_p (x, needed, note, insn)
1810 register RTX_CODE code = GET_CODE (x);
1814 register rtx r = SET_SRC (x);
1815 if (GET_CODE (r) == REG)
1817 rtx call = XEXP (note, 0);
1820 /* Find the call insn. */
1821 while (call != insn && GET_CODE (call) != CALL_INSN)
1822 call = NEXT_INSN (call);
1824 /* If there is none, do nothing special,
1825 since ordinary death handling can understand these insns. */
1829 /* See if the hard reg holding the value is dead.
1830 If this is a PARALLEL, find the call within it. */
1831 call = PATTERN (call);
1832 if (GET_CODE (call) == PARALLEL)
1834 for (i = XVECLEN (call, 0) - 1; i >= 0; i--)
1835 if (GET_CODE (XVECEXP (call, 0, i)) == SET
1836 && GET_CODE (SET_SRC (XVECEXP (call, 0, i))) == CALL)
1839 /* This may be a library call that is returning a value
1840 via invisible pointer. Do nothing special, since
1841 ordinary death handling can understand these insns. */
1845 call = XVECEXP (call, 0, i);
1848 return insn_dead_p (call, needed, 1);
1854 /* Return 1 if register REGNO was used before it was set.
1855 In other words, if it is live at function entry.
1856 Don't count global regster variables, though. */
1859 regno_uninitialized (regno)
1862 if (n_basic_blocks == 0
1863 || (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
1866 return (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1867 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS)));
1870 /* 1 if register REGNO was alive at a place where `setjmp' was called
1871 and was set more than once or is an argument.
1872 Such regs may be clobbered by `longjmp'. */
1875 regno_clobbered_at_setjmp (regno)
1878 if (n_basic_blocks == 0)
1881 return ((reg_n_sets[regno] > 1
1882 || (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1883 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))))
1884 && (regs_live_at_setjmp[regno / REGSET_ELT_BITS]
1885 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))));
1888 /* Process the registers that are set within X.
1889 Their bits are set to 1 in the regset DEAD,
1890 because they are dead prior to this insn.
1892 If INSN is nonzero, it is the insn being processed
1893 and the fact that it is nonzero implies this is the FINAL pass
1894 in propagate_block. In this case, various info about register
1895 usage is stored, LOG_LINKS fields of insns are set up. */
1898 mark_set_regs (needed, dead, x, insn, significant)
1905 register RTX_CODE code = GET_CODE (x);
1907 if (code == SET || code == CLOBBER)
1908 mark_set_1 (needed, dead, x, insn, significant);
1909 else if (code == PARALLEL)
1912 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
1914 code = GET_CODE (XVECEXP (x, 0, i));
1915 if (code == SET || code == CLOBBER)
1916 mark_set_1 (needed, dead, XVECEXP (x, 0, i), insn, significant);
1921 /* Process a single SET rtx, X. */
1924 mark_set_1 (needed, dead, x, insn, significant)
1932 register rtx reg = SET_DEST (x);
1934 /* Modifying just one hardware register of a multi-reg value
1935 or just a byte field of a register
1936 does not mean the value from before this insn is now dead.
1937 But it does mean liveness of that register at the end of the block
1940 Within mark_set_1, however, we treat it as if the register is
1941 indeed modified. mark_used_regs will, however, also treat this
1942 register as being used. Thus, we treat these insns as setting a
1943 new value for the register as a function of its old value. This
1944 cases LOG_LINKS to be made appropriately and this will help combine. */
1946 while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
1947 || GET_CODE (reg) == SIGN_EXTRACT
1948 || GET_CODE (reg) == STRICT_LOW_PART)
1949 reg = XEXP (reg, 0);
1951 /* If we are writing into memory or into a register mentioned in the
1952 address of the last thing stored into memory, show we don't know
1953 what the last store was. If we are writing memory, save the address
1954 unless it is volatile. */
1955 if (GET_CODE (reg) == MEM
1956 || (GET_CODE (reg) == REG
1957 && last_mem_set != 0 && reg_overlap_mentioned_p (reg, last_mem_set)))
1960 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
1961 /* There are no REG_INC notes for SP, so we can't assume we'll see
1962 everything that invalidates it. To be safe, don't eliminate any
1963 stores though SP; none of them should be redundant anyway. */
1964 && ! reg_mentioned_p (stack_pointer_rtx, reg))
1967 if (GET_CODE (reg) == REG
1968 && (regno = REGNO (reg), regno != FRAME_POINTER_REGNUM)
1969 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1970 && regno != HARD_FRAME_POINTER_REGNUM
1972 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1973 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1975 && ! (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
1976 /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
1978 register int offset = regno / REGSET_ELT_BITS;
1979 register REGSET_ELT_TYPE bit
1980 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
1981 REGSET_ELT_TYPE all_needed = (needed[offset] & bit);
1982 REGSET_ELT_TYPE some_needed = (needed[offset] & bit);
1984 /* Mark it as a significant register for this basic block. */
1986 significant[offset] |= bit;
1988 /* Mark it as as dead before this insn. */
1989 dead[offset] |= bit;
1991 /* A hard reg in a wide mode may really be multiple registers.
1992 If so, mark all of them just like the first. */
1993 if (regno < FIRST_PSEUDO_REGISTER)
1997 /* Nothing below is needed for the stack pointer; get out asap.
1998 Eg, log links aren't needed, since combine won't use them. */
1999 if (regno == STACK_POINTER_REGNUM)
2002 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
2006 significant[(regno + n) / REGSET_ELT_BITS]
2007 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
2008 dead[(regno + n) / REGSET_ELT_BITS]
2009 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
2011 |= (needed[(regno + n) / REGSET_ELT_BITS]
2012 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2014 &= (needed[(regno + n) / REGSET_ELT_BITS]
2015 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2018 /* Additional data to record if this is the final pass. */
2021 register rtx y = reg_next_use[regno];
2022 register int blocknum = BLOCK_NUM (insn);
2024 /* If this is a hard reg, record this function uses the reg. */
2026 if (regno < FIRST_PSEUDO_REGISTER)
2029 int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg));
2031 for (i = regno; i < endregno; i++)
2033 /* The next use is no longer "next", since a store
2035 reg_next_use[i] = 0;
2037 regs_ever_live[i] = 1;
2043 /* The next use is no longer "next", since a store
2045 reg_next_use[regno] = 0;
2047 /* Keep track of which basic blocks each reg appears in. */
2049 if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
2050 reg_basic_block[regno] = blocknum;
2051 else if (reg_basic_block[regno] != blocknum)
2052 reg_basic_block[regno] = REG_BLOCK_GLOBAL;
2054 /* Count (weighted) references, stores, etc. This counts a
2055 register twice if it is modified, but that is correct. */
2056 reg_n_sets[regno]++;
2058 reg_n_refs[regno] += loop_depth;
2060 /* The insns where a reg is live are normally counted
2061 elsewhere, but we want the count to include the insn
2062 where the reg is set, and the normal counting mechanism
2063 would not count it. */
2064 reg_live_length[regno]++;
2069 /* Make a logical link from the next following insn
2070 that uses this register, back to this insn.
2071 The following insns have already been processed.
2073 We don't build a LOG_LINK for hard registers containing
2074 in ASM_OPERANDs. If these registers get replaced,
2075 we might wind up changing the semantics of the insn,
2076 even if reload can make what appear to be valid assignments
2078 if (y && (BLOCK_NUM (y) == blocknum)
2079 && (regno >= FIRST_PSEUDO_REGISTER
2080 || asm_noperands (PATTERN (y)) < 0))
2082 = gen_rtx (INSN_LIST, VOIDmode, insn, LOG_LINKS (y));
2084 else if (! some_needed)
2086 /* Note that dead stores have already been deleted when possible
2087 If we get here, we have found a dead store that cannot
2088 be eliminated (because the same insn does something useful).
2089 Indicate this by marking the reg being set as dying here. */
2091 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
2092 reg_n_deaths[REGNO (reg)]++;
2096 /* This is a case where we have a multi-word hard register
2097 and some, but not all, of the words of the register are
2098 needed in subsequent insns. Write REG_UNUSED notes
2099 for those parts that were not needed. This case should
2104 for (i = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1;
2106 if ((needed[(regno + i) / REGSET_ELT_BITS]
2107 & ((REGSET_ELT_TYPE) 1
2108 << ((regno + i) % REGSET_ELT_BITS))) == 0)
2110 = gen_rtx (EXPR_LIST, REG_UNUSED,
2111 gen_rtx (REG, reg_raw_mode[regno + i],
2117 else if (GET_CODE (reg) == REG)
2118 reg_next_use[regno] = 0;
2120 /* If this is the last pass and this is a SCRATCH, show it will be dying
2121 here and count it. */
2122 else if (GET_CODE (reg) == SCRATCH && insn != 0)
2125 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
2132 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
2136 find_auto_inc (needed, x, insn)
2141 rtx addr = XEXP (x, 0);
2142 HOST_WIDE_INT offset = 0;
2145 /* Here we detect use of an index register which might be good for
2146 postincrement, postdecrement, preincrement, or predecrement. */
2148 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
2149 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
2151 if (GET_CODE (addr) == REG)
2154 register int size = GET_MODE_SIZE (GET_MODE (x));
2157 int regno = REGNO (addr);
2159 /* Is the next use an increment that might make auto-increment? */
2160 if ((incr = reg_next_use[regno]) != 0
2161 && (set = single_set (incr)) != 0
2162 && GET_CODE (set) == SET
2163 && BLOCK_NUM (incr) == BLOCK_NUM (insn)
2164 /* Can't add side effects to jumps; if reg is spilled and
2165 reloaded, there's no way to store back the altered value. */
2166 && GET_CODE (insn) != JUMP_INSN
2167 && (y = SET_SRC (set), GET_CODE (y) == PLUS)
2168 && XEXP (y, 0) == addr
2169 && GET_CODE (XEXP (y, 1)) == CONST_INT
2171 #ifdef HAVE_POST_INCREMENT
2172 || (INTVAL (XEXP (y, 1)) == size && offset == 0)
2174 #ifdef HAVE_POST_DECREMENT
2175 || (INTVAL (XEXP (y, 1)) == - size && offset == 0)
2177 #ifdef HAVE_PRE_INCREMENT
2178 || (INTVAL (XEXP (y, 1)) == size && offset == size)
2180 #ifdef HAVE_PRE_DECREMENT
2181 || (INTVAL (XEXP (y, 1)) == - size && offset == - size)
2184 /* Make sure this reg appears only once in this insn. */
2185 && (use = find_use_as_address (PATTERN (insn), addr, offset),
2186 use != 0 && use != (rtx) 1))
2188 rtx q = SET_DEST (set);
2189 enum rtx_code inc_code = (INTVAL (XEXP (y, 1)) == size
2190 ? (offset ? PRE_INC : POST_INC)
2191 : (offset ? PRE_DEC : POST_DEC));
2193 if (dead_or_set_p (incr, addr))
2195 /* This is the simple case. Try to make the auto-inc. If
2196 we can't, we are done. Otherwise, we will do any
2197 needed updates below. */
2198 if (! validate_change (insn, &XEXP (x, 0),
2199 gen_rtx (inc_code, Pmode, addr),
2203 else if (GET_CODE (q) == REG
2204 /* PREV_INSN used here to check the semi-open interval
2206 && ! reg_used_between_p (q, PREV_INSN (insn), incr))
2208 /* We have *p followed sometime later by q = p+size.
2209 Both p and q must be live afterward,
2210 and q is not used between INSN and it's assignment.
2211 Change it to q = p, ...*q..., q = q+size.
2212 Then fall into the usual case. */
2216 emit_move_insn (q, addr);
2217 insns = get_insns ();
2220 /* If anything in INSNS have UID's that don't fit within the
2221 extra space we allocate earlier, we can't make this auto-inc.
2222 This should never happen. */
2223 for (temp = insns; temp; temp = NEXT_INSN (temp))
2225 if (INSN_UID (temp) > max_uid_for_flow)
2227 BLOCK_NUM (temp) = BLOCK_NUM (insn);
2230 /* If we can't make the auto-inc, or can't make the
2231 replacement into Y, exit. There's no point in making
2232 the change below if we can't do the auto-inc and doing
2233 so is not correct in the pre-inc case. */
2235 validate_change (insn, &XEXP (x, 0),
2236 gen_rtx (inc_code, Pmode, q),
2238 validate_change (incr, &XEXP (y, 0), q, 1);
2239 if (! apply_change_group ())
2242 /* We now know we'll be doing this change, so emit the
2243 new insn(s) and do the updates. */
2244 emit_insns_before (insns, insn);
2246 if (basic_block_head[BLOCK_NUM (insn)] == insn)
2247 basic_block_head[BLOCK_NUM (insn)] = insns;
2249 /* INCR will become a NOTE and INSN won't contain a
2250 use of ADDR. If a use of ADDR was just placed in
2251 the insn before INSN, make that the next use.
2252 Otherwise, invalidate it. */
2253 if (GET_CODE (PREV_INSN (insn)) == INSN
2254 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
2255 && SET_SRC (PATTERN (PREV_INSN (insn))) == addr)
2256 reg_next_use[regno] = PREV_INSN (insn);
2258 reg_next_use[regno] = 0;
2263 /* REGNO is now used in INCR which is below INSN, but
2264 it previously wasn't live here. If we don't mark
2265 it as needed, we'll put a REG_DEAD note for it
2266 on this insn, which is incorrect. */
2267 needed[regno / REGSET_ELT_BITS]
2268 |= (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2270 /* If there are any calls between INSN and INCR, show
2271 that REGNO now crosses them. */
2272 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
2273 if (GET_CODE (temp) == CALL_INSN)
2274 reg_n_calls_crossed[regno]++;
2279 /* If we haven't returned, it means we were able to make the
2280 auto-inc, so update the status. First, record that this insn
2281 has an implicit side effect. */
2284 = gen_rtx (EXPR_LIST, REG_INC, addr, REG_NOTES (insn));
2286 /* Modify the old increment-insn to simply copy
2287 the already-incremented value of our register. */
2288 if (! validate_change (incr, &SET_SRC (set), addr, 0))
2291 /* If that makes it a no-op (copying the register into itself) delete
2292 it so it won't appear to be a "use" and a "set" of this
2294 if (SET_DEST (set) == addr)
2296 PUT_CODE (incr, NOTE);
2297 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
2298 NOTE_SOURCE_FILE (incr) = 0;
2301 if (regno >= FIRST_PSEUDO_REGISTER)
2303 /* Count an extra reference to the reg. When a reg is
2304 incremented, spilling it is worse, so we want to make
2305 that less likely. */
2306 reg_n_refs[regno] += loop_depth;
2308 /* Count the increment as a setting of the register,
2309 even though it isn't a SET in rtl. */
2310 reg_n_sets[regno]++;
2315 #endif /* AUTO_INC_DEC */
2317 /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
2318 This is done assuming the registers needed from X
2319 are those that have 1-bits in NEEDED.
2321 On the final pass, FINAL is 1. This means try for autoincrement
2322 and count the uses and deaths of each pseudo-reg.
2324 INSN is the containing instruction. If INSN is dead, this function is not
2328 mark_used_regs (needed, live, x, final, insn)
2335 register RTX_CODE code;
2340 code = GET_CODE (x);
2361 /* If we are clobbering a MEM, mark any registers inside the address
2363 if (GET_CODE (XEXP (x, 0)) == MEM)
2364 mark_used_regs (needed, live, XEXP (XEXP (x, 0), 0), final, insn);
2368 /* Invalidate the data for the last MEM stored. We could do this only
2369 if the addresses conflict, but this doesn't seem worthwhile. */
2374 find_auto_inc (needed, x, insn);
2379 if (GET_CODE (SUBREG_REG (x)) == REG
2380 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
2381 && (GET_MODE_SIZE (GET_MODE (x))
2382 != GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))))
2383 reg_changes_size[REGNO (SUBREG_REG (x))] = 1;
2385 /* While we're here, optimize this case. */
2388 /* Must verify that it is a register, since the RS/6000 port has
2389 (subreg:QI (lshift:SI ...)). */
2390 if (GET_CODE (x) != REG)
2393 /* ... fall through ... */
2396 /* See a register other than being set
2397 => mark it as needed. */
2401 register int offset = regno / REGSET_ELT_BITS;
2402 register REGSET_ELT_TYPE bit
2403 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2404 REGSET_ELT_TYPE all_needed = needed[offset] & bit;
2405 REGSET_ELT_TYPE some_needed = needed[offset] & bit;
2407 live[offset] |= bit;
2408 /* A hard reg in a wide mode may really be multiple registers.
2409 If so, mark all of them just like the first. */
2410 if (regno < FIRST_PSEUDO_REGISTER)
2414 /* For stack ptr or fixed arg pointer,
2415 nothing below can be necessary, so waste no more time. */
2416 if (regno == STACK_POINTER_REGNUM
2417 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2418 || regno == HARD_FRAME_POINTER_REGNUM
2420 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2421 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2423 || regno == FRAME_POINTER_REGNUM)
2425 /* If this is a register we are going to try to eliminate,
2426 don't mark it live here. If we are successful in
2427 eliminating it, it need not be live unless it is used for
2428 pseudos, in which case it will have been set live when
2429 it was allocated to the pseudos. If the register will not
2430 be eliminated, reload will set it live at that point. */
2432 if (! TEST_HARD_REG_BIT (elim_reg_set, regno))
2433 regs_ever_live[regno] = 1;
2436 /* No death notes for global register variables;
2437 their values are live after this function exits. */
2438 if (global_regs[regno])
2441 reg_next_use[regno] = insn;
2445 n = HARD_REGNO_NREGS (regno, GET_MODE (x));
2448 live[(regno + n) / REGSET_ELT_BITS]
2449 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
2451 |= (needed[(regno + n) / REGSET_ELT_BITS]
2452 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2454 &= (needed[(regno + n) / REGSET_ELT_BITS]
2455 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2460 /* Record where each reg is used, so when the reg
2461 is set we know the next insn that uses it. */
2463 reg_next_use[regno] = insn;
2465 if (regno < FIRST_PSEUDO_REGISTER)
2467 /* If a hard reg is being used,
2468 record that this function does use it. */
2470 i = HARD_REGNO_NREGS (regno, GET_MODE (x));
2474 regs_ever_live[regno + --i] = 1;
2479 /* Keep track of which basic block each reg appears in. */
2481 register int blocknum = BLOCK_NUM (insn);
2483 if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
2484 reg_basic_block[regno] = blocknum;
2485 else if (reg_basic_block[regno] != blocknum)
2486 reg_basic_block[regno] = REG_BLOCK_GLOBAL;
2488 /* Count (weighted) number of uses of each reg. */
2490 reg_n_refs[regno] += loop_depth;
2493 /* Record and count the insns in which a reg dies.
2494 If it is used in this insn and was dead below the insn
2495 then it dies in this insn. If it was set in this insn,
2496 we do not make a REG_DEAD note; likewise if we already
2497 made such a note. */
2500 && ! dead_or_set_p (insn, x)
2502 && (regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
2506 /* Check for the case where the register dying partially
2507 overlaps the register set by this insn. */
2508 if (regno < FIRST_PSEUDO_REGISTER
2509 && HARD_REGNO_NREGS (regno, GET_MODE (x)) > 1)
2511 int n = HARD_REGNO_NREGS (regno, GET_MODE (x));
2513 some_needed |= dead_or_set_regno_p (insn, regno + n);
2516 /* If none of the words in X is needed, make a REG_DEAD
2517 note. Otherwise, we must make partial REG_DEAD notes. */
2521 = gen_rtx (EXPR_LIST, REG_DEAD, x, REG_NOTES (insn));
2522 reg_n_deaths[regno]++;
2528 /* Don't make a REG_DEAD note for a part of a register
2529 that is set in the insn. */
2531 for (i = HARD_REGNO_NREGS (regno, GET_MODE (x)) - 1;
2533 if ((needed[(regno + i) / REGSET_ELT_BITS]
2534 & ((REGSET_ELT_TYPE) 1
2535 << ((regno + i) % REGSET_ELT_BITS))) == 0
2536 && ! dead_or_set_regno_p (insn, regno + i))
2538 = gen_rtx (EXPR_LIST, REG_DEAD,
2539 gen_rtx (REG, reg_raw_mode[regno + i],
2550 register rtx testreg = SET_DEST (x);
2553 /* If storing into MEM, don't show it as being used. But do
2554 show the address as being used. */
2555 if (GET_CODE (testreg) == MEM)
2559 find_auto_inc (needed, testreg, insn);
2561 mark_used_regs (needed, live, XEXP (testreg, 0), final, insn);
2562 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2566 /* Storing in STRICT_LOW_PART is like storing in a reg
2567 in that this SET might be dead, so ignore it in TESTREG.
2568 but in some other ways it is like using the reg.
2570 Storing in a SUBREG or a bit field is like storing the entire
2571 register in that if the register's value is not used
2572 then this SET is not needed. */
2573 while (GET_CODE (testreg) == STRICT_LOW_PART
2574 || GET_CODE (testreg) == ZERO_EXTRACT
2575 || GET_CODE (testreg) == SIGN_EXTRACT
2576 || GET_CODE (testreg) == SUBREG)
2578 if (GET_CODE (testreg) == SUBREG
2579 && GET_CODE (SUBREG_REG (testreg)) == REG
2580 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
2581 && (GET_MODE_SIZE (GET_MODE (testreg))
2582 != GET_MODE_SIZE (GET_MODE (SUBREG_REG (testreg)))))
2583 reg_changes_size[REGNO (SUBREG_REG (testreg))] = 1;
2585 /* Modifying a single register in an alternate mode
2586 does not use any of the old value. But these other
2587 ways of storing in a register do use the old value. */
2588 if (GET_CODE (testreg) == SUBREG
2589 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
2594 testreg = XEXP (testreg, 0);
2597 /* If this is a store into a register,
2598 recursively scan the value being stored. */
2600 if (GET_CODE (testreg) == REG
2601 && (regno = REGNO (testreg), regno != FRAME_POINTER_REGNUM)
2602 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2603 && regno != HARD_FRAME_POINTER_REGNUM
2605 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2606 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2609 /* We used to exclude global_regs here, but that seems wrong.
2610 Storing in them is like storing in mem. */
2612 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2614 mark_used_regs (needed, live, SET_DEST (x), final, insn);
2621 /* If exiting needs the right stack value, consider this insn as
2622 using the stack pointer. In any event, consider it as using
2623 all global registers. */
2625 #ifdef EXIT_IGNORE_STACK
2626 if (! EXIT_IGNORE_STACK
2627 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
2629 live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
2630 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
2632 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2634 live[i / REGSET_ELT_BITS]
2635 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
2639 /* Recursively scan the operands of this expression. */
2642 register char *fmt = GET_RTX_FORMAT (code);
2645 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2649 /* Tail recursive case: save a function call level. */
2655 mark_used_regs (needed, live, XEXP (x, i), final, insn);
2657 else if (fmt[i] == 'E')
2660 for (j = 0; j < XVECLEN (x, i); j++)
2661 mark_used_regs (needed, live, XVECEXP (x, i, j), final, insn);
2670 try_pre_increment_1 (insn)
2673 /* Find the next use of this reg. If in same basic block,
2674 make it do pre-increment or pre-decrement if appropriate. */
2675 rtx x = PATTERN (insn);
2676 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
2677 * INTVAL (XEXP (SET_SRC (x), 1)));
2678 int regno = REGNO (SET_DEST (x));
2679 rtx y = reg_next_use[regno];
2681 && BLOCK_NUM (y) == BLOCK_NUM (insn)
2682 /* Don't do this if the reg dies, or gets set in y; a standard addressing
2683 mode would be better. */
2684 && ! dead_or_set_p (y, SET_DEST (x))
2685 && try_pre_increment (y, SET_DEST (PATTERN (insn)),
2688 /* We have found a suitable auto-increment
2689 and already changed insn Y to do it.
2690 So flush this increment-instruction. */
2691 PUT_CODE (insn, NOTE);
2692 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
2693 NOTE_SOURCE_FILE (insn) = 0;
2694 /* Count a reference to this reg for the increment
2695 insn we are deleting. When a reg is incremented.
2696 spilling it is worse, so we want to make that
2698 if (regno >= FIRST_PSEUDO_REGISTER)
2700 reg_n_refs[regno] += loop_depth;
2701 reg_n_sets[regno]++;
2708 /* Try to change INSN so that it does pre-increment or pre-decrement
2709 addressing on register REG in order to add AMOUNT to REG.
2710 AMOUNT is negative for pre-decrement.
2711 Returns 1 if the change could be made.
2712 This checks all about the validity of the result of modifying INSN. */
2715 try_pre_increment (insn, reg, amount)
2717 HOST_WIDE_INT amount;
2721 /* Nonzero if we can try to make a pre-increment or pre-decrement.
2722 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
2724 /* Nonzero if we can try to make a post-increment or post-decrement.
2725 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
2726 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
2727 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
2730 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
2733 /* From the sign of increment, see which possibilities are conceivable
2734 on this target machine. */
2735 #ifdef HAVE_PRE_INCREMENT
2739 #ifdef HAVE_POST_INCREMENT
2744 #ifdef HAVE_PRE_DECREMENT
2748 #ifdef HAVE_POST_DECREMENT
2753 if (! (pre_ok || post_ok))
2756 /* It is not safe to add a side effect to a jump insn
2757 because if the incremented register is spilled and must be reloaded
2758 there would be no way to store the incremented value back in memory. */
2760 if (GET_CODE (insn) == JUMP_INSN)
2765 use = find_use_as_address (PATTERN (insn), reg, 0);
2766 if (post_ok && (use == 0 || use == (rtx) 1))
2768 use = find_use_as_address (PATTERN (insn), reg, -amount);
2772 if (use == 0 || use == (rtx) 1)
2775 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
2778 /* See if this combination of instruction and addressing mode exists. */
2779 if (! validate_change (insn, &XEXP (use, 0),
2781 ? (do_post ? POST_INC : PRE_INC)
2782 : (do_post ? POST_DEC : PRE_DEC),
2786 /* Record that this insn now has an implicit side effect on X. */
2787 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_INC, reg, REG_NOTES (insn));
2791 #endif /* AUTO_INC_DEC */
2793 /* Find the place in the rtx X where REG is used as a memory address.
2794 Return the MEM rtx that so uses it.
2795 If PLUSCONST is nonzero, search instead for a memory address equivalent to
2796 (plus REG (const_int PLUSCONST)).
2798 If such an address does not appear, return 0.
2799 If REG appears more than once, or is used other than in such an address,
2803 find_use_as_address (x, reg, plusconst)
2806 HOST_WIDE_INT plusconst;
2808 enum rtx_code code = GET_CODE (x);
2809 char *fmt = GET_RTX_FORMAT (code);
2811 register rtx value = 0;
2814 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
2817 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
2818 && XEXP (XEXP (x, 0), 0) == reg
2819 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
2820 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
2823 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
2825 /* If REG occurs inside a MEM used in a bit-field reference,
2826 that is unacceptable. */
2827 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
2828 return (rtx) (HOST_WIDE_INT) 1;
2832 return (rtx) (HOST_WIDE_INT) 1;
2834 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2838 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
2842 return (rtx) (HOST_WIDE_INT) 1;
2847 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
2849 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
2853 return (rtx) (HOST_WIDE_INT) 1;
2861 /* Write information about registers and basic blocks into FILE.
2862 This is part of making a debugging dump. */
2865 dump_flow_info (file)
2869 static char *reg_class_names[] = REG_CLASS_NAMES;
2871 fprintf (file, "%d registers.\n", max_regno);
2873 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
2876 enum reg_class class, altclass;
2877 fprintf (file, "\nRegister %d used %d times across %d insns",
2878 i, reg_n_refs[i], reg_live_length[i]);
2879 if (reg_basic_block[i] >= 0)
2880 fprintf (file, " in block %d", reg_basic_block[i]);
2881 if (reg_n_deaths[i] != 1)
2882 fprintf (file, "; dies in %d places", reg_n_deaths[i]);
2883 if (reg_n_calls_crossed[i] == 1)
2884 fprintf (file, "; crosses 1 call");
2885 else if (reg_n_calls_crossed[i])
2886 fprintf (file, "; crosses %d calls", reg_n_calls_crossed[i]);
2887 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
2888 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
2889 class = reg_preferred_class (i);
2890 altclass = reg_alternate_class (i);
2891 if (class != GENERAL_REGS || altclass != ALL_REGS)
2893 if (altclass == ALL_REGS || class == ALL_REGS)
2894 fprintf (file, "; pref %s", reg_class_names[(int) class]);
2895 else if (altclass == NO_REGS)
2896 fprintf (file, "; %s or none", reg_class_names[(int) class]);
2898 fprintf (file, "; pref %s, else %s",
2899 reg_class_names[(int) class],
2900 reg_class_names[(int) altclass]);
2902 if (REGNO_POINTER_FLAG (i))
2903 fprintf (file, "; pointer");
2904 fprintf (file, ".\n");
2906 fprintf (file, "\n%d basic blocks.\n", n_basic_blocks);
2907 for (i = 0; i < n_basic_blocks; i++)
2909 register rtx head, jump;
2911 fprintf (file, "\nBasic block %d: first insn %d, last %d.\n",
2913 INSN_UID (basic_block_head[i]),
2914 INSN_UID (basic_block_end[i]));
2915 /* The control flow graph's storage is freed
2916 now when flow_analysis returns.
2917 Don't try to print it if it is gone. */
2918 if (basic_block_drops_in)
2920 fprintf (file, "Reached from blocks: ");
2921 head = basic_block_head[i];
2922 if (GET_CODE (head) == CODE_LABEL)
2923 for (jump = LABEL_REFS (head);
2925 jump = LABEL_NEXTREF (jump))
2927 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
2928 fprintf (file, " %d", from_block);
2930 if (basic_block_drops_in[i])
2931 fprintf (file, " previous");
2933 fprintf (file, "\nRegisters live at start:");
2934 for (regno = 0; regno < max_regno; regno++)
2936 register int offset = regno / REGSET_ELT_BITS;
2937 register REGSET_ELT_TYPE bit
2938 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2939 if (basic_block_live_at_start[i][offset] & bit)
2940 fprintf (file, " %d", regno);
2942 fprintf (file, "\n");
2944 fprintf (file, "\n");