1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994 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, gives number of places register N dies.
181 This information remains valid for the rest of the compilation
182 of the current function; it is used to control register allocation. */
186 /* Indexed by N, gives 1 if that reg is live across any CALL_INSNs.
187 This information remains valid for the rest of the compilation
188 of the current function; it is used to control register allocation. */
190 int *reg_n_calls_crossed;
192 /* Total number of instructions at which (REG n) is live.
193 The larger this is, the less priority (REG n) gets for
194 allocation in a real register.
195 This information remains valid for the rest of the compilation
196 of the current function; it is used to control register allocation.
198 local-alloc.c may alter this number to change the priority.
200 Negative values are special.
201 -1 is used to mark a pseudo reg which has a constant or memory equivalent
202 and is used infrequently enough that it should not get a hard register.
203 -2 is used to mark a pseudo reg for a parameter, when a frame pointer
204 is not required. global.c makes an allocno for this but does
205 not try to assign a hard register to it. */
207 int *reg_live_length;
209 /* Element N is the next insn that uses (hard or pseudo) register number N
210 within the current basic block; or zero, if there is no such insn.
211 This is valid only during the final backward scan in propagate_block. */
213 static rtx *reg_next_use;
215 /* Size of a regset for the current function,
216 in (1) bytes and (2) elements. */
221 /* Element N is first insn in basic block N.
222 This info lasts until we finish compiling the function. */
224 rtx *basic_block_head;
226 /* Element N is last insn in basic block N.
227 This info lasts until we finish compiling the function. */
229 rtx *basic_block_end;
231 /* Element N is a regset describing the registers live
232 at the start of basic block N.
233 This info lasts until we finish compiling the function. */
235 regset *basic_block_live_at_start;
237 /* Regset of regs live when calls to `setjmp'-like functions happen. */
239 regset regs_live_at_setjmp;
241 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
242 that have to go in the same hard reg.
243 The first two regs in the list are a pair, and the next two
244 are another pair, etc. */
247 /* Element N is nonzero if control can drop into basic block N
248 from the preceding basic block. Freed after life_analysis. */
250 static char *basic_block_drops_in;
252 /* Element N is depth within loops of the last insn in basic block number N.
253 Freed after life_analysis. */
255 static short *basic_block_loop_depth;
257 /* Element N nonzero if basic block N can actually be reached.
258 Vector exists only during find_basic_blocks. */
260 static char *block_live_static;
262 /* Depth within loops of basic block being scanned for lifetime analysis,
263 plus one. This is the weight attached to references to registers. */
265 static int loop_depth;
267 /* During propagate_block, this is non-zero if the value of CC0 is live. */
271 /* During propagate_block, this contains the last MEM stored into. It
272 is used to eliminate consecutive stores to the same location. */
274 static rtx last_mem_set;
276 /* Set of registers that may be eliminable. These are handled specially
277 in updating regs_ever_live. */
279 static HARD_REG_SET elim_reg_set;
281 /* Forward declarations */
282 static void find_basic_blocks PROTO((rtx, rtx));
283 static int uses_reg_or_mem PROTO((rtx));
284 static void mark_label_ref PROTO((rtx, rtx, int));
285 static void life_analysis PROTO((rtx, int));
286 void allocate_for_life_analysis PROTO((void));
287 static void init_regset_vector PROTO((regset *, regset, int, int));
288 static void propagate_block PROTO((regset, rtx, rtx, int,
290 static int insn_dead_p PROTO((rtx, regset, int));
291 static int libcall_dead_p PROTO((rtx, regset, rtx, rtx));
292 static void mark_set_regs PROTO((regset, regset, rtx,
294 static void mark_set_1 PROTO((regset, regset, rtx,
296 static void find_auto_inc PROTO((regset, rtx, rtx));
297 static void mark_used_regs PROTO((regset, regset, rtx, int, rtx));
298 static int try_pre_increment_1 PROTO((rtx));
299 static int try_pre_increment PROTO((rtx, rtx, HOST_WIDE_INT));
300 static rtx find_use_as_address PROTO((rtx, rtx, HOST_WIDE_INT));
301 void dump_flow_info PROTO((FILE *));
303 /* Find basic blocks of the current function and perform data flow analysis.
304 F is the first insn of the function and NREGS the number of register numbers
308 flow_analysis (f, nregs, file)
315 rtx nonlocal_label_list = nonlocal_label_rtx_list ();
317 #ifdef ELIMINABLE_REGS
318 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
321 /* Record which registers will be eliminated. We use this in
324 CLEAR_HARD_REG_SET (elim_reg_set);
326 #ifdef ELIMINABLE_REGS
327 for (i = 0; i < sizeof eliminables / sizeof eliminables[0]; i++)
328 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
330 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
333 /* Count the basic blocks. Also find maximum insn uid value used. */
336 register RTX_CODE prev_code = JUMP_INSN;
337 register RTX_CODE code;
339 max_uid_for_flow = 0;
341 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
343 code = GET_CODE (insn);
344 if (INSN_UID (insn) > max_uid_for_flow)
345 max_uid_for_flow = INSN_UID (insn);
346 if (code == CODE_LABEL
347 || (GET_RTX_CLASS (code) == 'i'
348 && (prev_code == JUMP_INSN
349 || (prev_code == CALL_INSN
350 && nonlocal_label_list != 0
351 /* Ignore a CLOBBER after a CALL_INSN here. */
353 && GET_CODE (PATTERN (insn)) == CLOBBER))
354 || prev_code == BARRIER)))
357 /* Skip a CLOBBER after a CALL_INSN. See similar code in
358 find_basic_blocks. */
359 && ! (prev_code == CALL_INSN
360 && code == INSN && GET_CODE (PATTERN (insn)) == CLOBBER))
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 = 0;
413 enum rtx_code prev_code, code;
416 block_live_static = block_live;
417 bzero (block_live, n_basic_blocks);
418 bzero (block_marked, n_basic_blocks);
420 /* Initialize with just block 0 reachable and no blocks marked. */
421 if (n_basic_blocks > 0)
424 /* Initialize the ref chain of each label to 0. Record where all the
425 blocks start and end and their depth in loops. For each insn, record
426 the block it is in. Also mark as reachable any blocks headed by labels
427 that must not be deleted. */
429 for (insn = f, i = -1, prev_code = JUMP_INSN, depth = 1;
430 insn; insn = NEXT_INSN (insn))
432 code = GET_CODE (insn);
435 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
437 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
441 /* A basic block starts at label, or after something that can jump. */
442 else if (code == CODE_LABEL
443 || (GET_RTX_CLASS (code) == 'i'
444 && (prev_code == JUMP_INSN
445 || (prev_code == CALL_INSN
446 && nonlocal_label_list != 0
447 /* Ignore if CLOBBER since we consider this
448 part of the CALL. See below. */
450 && GET_CODE (PATTERN (insn)) == CLOBBER))
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;
484 /* Don't separate a CALL_INSN from following CLOBBER insns. This is a
485 kludge that will go away when each CALL_INSN records its USE and
489 && ! (prev_code == CALL_INSN && code == INSN
490 && GET_CODE (PATTERN (insn)) == CLOBBER))
494 if (i + 1 != n_basic_blocks)
497 /* Don't delete the labels (in this function)
498 that are referenced by non-jump instructions. */
500 for (x = label_value_list; x; x = XEXP (x, 1))
501 if (! LABEL_REF_NONLOCAL_P (x))
502 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
504 for (x = forced_labels; x; x = XEXP (x, 1))
505 if (! LABEL_REF_NONLOCAL_P (x))
506 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
508 /* Record which basic blocks control can drop in to. */
510 for (i = 0; i < n_basic_blocks; i++)
512 for (insn = PREV_INSN (basic_block_head[i]);
513 insn && GET_CODE (insn) == NOTE; insn = PREV_INSN (insn))
516 basic_block_drops_in[i] = insn && GET_CODE (insn) != BARRIER;
519 /* Now find which basic blocks can actually be reached
520 and put all jump insns' LABEL_REFS onto the ref-chains
521 of their target labels. */
523 if (n_basic_blocks > 0)
525 int something_marked = 1;
527 /* Find all indirect jump insns and mark them as possibly jumping to all
528 the labels whose addresses are explicitly used. This is because,
529 when there are computed gotos, we can't tell which labels they jump
530 to, of all the possibilities.
532 Tablejumps and casesi insns are OK and we can recognize them by
533 a (use (label_ref)). */
535 for (insn = f; insn; insn = NEXT_INSN (insn))
536 if (GET_CODE (insn) == JUMP_INSN)
538 rtx pat = PATTERN (insn);
539 int computed_jump = 0;
541 if (GET_CODE (pat) == PARALLEL)
543 int len = XVECLEN (pat, 0);
544 int has_use_labelref = 0;
546 for (i = len - 1; i >= 0; i--)
547 if (GET_CODE (XVECEXP (pat, 0, i)) == USE
548 && (GET_CODE (XEXP (XVECEXP (pat, 0, i), 0))
550 has_use_labelref = 1;
552 if (! has_use_labelref)
553 for (i = len - 1; i >= 0; i--)
554 if (GET_CODE (XVECEXP (pat, 0, i)) == SET
555 && SET_DEST (XVECEXP (pat, 0, i)) == pc_rtx
556 && uses_reg_or_mem (SET_SRC (XVECEXP (pat, 0, i))))
559 else if (GET_CODE (pat) == SET
560 && SET_DEST (pat) == pc_rtx
561 && uses_reg_or_mem (SET_SRC (pat)))
566 for (x = label_value_list; x; x = XEXP (x, 1))
567 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
570 for (x = forced_labels; x; x = XEXP (x, 1))
571 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
576 /* Find all call insns and mark them as possibly jumping
577 to all the nonlocal goto handler labels. */
579 for (insn = f; insn; insn = NEXT_INSN (insn))
580 if (GET_CODE (insn) == CALL_INSN)
582 for (x = nonlocal_label_list; x; x = XEXP (x, 1))
583 /* Don't try marking labels that
584 were deleted as unreferenced. */
585 if (GET_CODE (XEXP (x, 0)) == CODE_LABEL)
586 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
589 /* ??? This could be made smarter:
590 in some cases it's possible to tell that certain
591 calls will not do a nonlocal goto.
593 For example, if the nested functions that do the
594 nonlocal gotos do not have their addresses taken, then
595 only calls to those functions or to other nested
596 functions that use them could possibly do nonlocal
600 /* Pass over all blocks, marking each block that is reachable
601 and has not yet been marked.
602 Keep doing this until, in one pass, no blocks have been marked.
603 Then blocks_live and blocks_marked are identical and correct.
604 In addition, all jumps actually reachable have been marked. */
606 while (something_marked)
608 something_marked = 0;
609 for (i = 0; i < n_basic_blocks; i++)
610 if (block_live[i] && !block_marked[i])
613 something_marked = 1;
614 if (i + 1 < n_basic_blocks && basic_block_drops_in[i + 1])
615 block_live[i + 1] = 1;
616 insn = basic_block_end[i];
617 if (GET_CODE (insn) == JUMP_INSN)
618 mark_label_ref (PATTERN (insn), insn, 0);
622 /* Now delete the code for any basic blocks that can't be reached.
623 They can occur because jump_optimize does not recognize
624 unreachable loops as unreachable. */
626 for (i = 0; i < n_basic_blocks; i++)
629 insn = basic_block_head[i];
632 if (GET_CODE (insn) == BARRIER)
634 if (GET_CODE (insn) != NOTE)
636 PUT_CODE (insn, NOTE);
637 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
638 NOTE_SOURCE_FILE (insn) = 0;
640 if (insn == basic_block_end[i])
642 /* BARRIERs are between basic blocks, not part of one.
643 Delete a BARRIER if the preceding jump is deleted.
644 We cannot alter a BARRIER into a NOTE
645 because it is too short; but we can really delete
646 it because it is not part of a basic block. */
647 if (NEXT_INSN (insn) != 0
648 && GET_CODE (NEXT_INSN (insn)) == BARRIER)
649 delete_insn (NEXT_INSN (insn));
652 insn = NEXT_INSN (insn);
654 /* Each time we delete some basic blocks,
655 see if there is a jump around them that is
656 being turned into a no-op. If so, delete it. */
658 if (block_live[i - 1])
661 for (j = i; j < n_basic_blocks; j++)
665 insn = basic_block_end[i - 1];
666 if (GET_CODE (insn) == JUMP_INSN
667 /* An unconditional jump is the only possibility
668 we must check for, since a conditional one
669 would make these blocks live. */
670 && simplejump_p (insn)
671 && (label = XEXP (SET_SRC (PATTERN (insn)), 0), 1)
672 && INSN_UID (label) != 0
673 && BLOCK_NUM (label) == j)
675 PUT_CODE (insn, NOTE);
676 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
677 NOTE_SOURCE_FILE (insn) = 0;
678 if (GET_CODE (NEXT_INSN (insn)) != BARRIER)
680 delete_insn (NEXT_INSN (insn));
689 /* Return 1 if X contain a REG or MEM that is not in the constant pool. */
695 enum rtx_code code = GET_CODE (x);
701 && ! (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
702 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))))
705 fmt = GET_RTX_FORMAT (code);
706 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
709 && uses_reg_or_mem (XEXP (x, i)))
713 for (j = 0; j < XVECLEN (x, i); j++)
714 if (uses_reg_or_mem (XVECEXP (x, i, j)))
721 /* Check expression X for label references;
722 if one is found, add INSN to the label's chain of references.
724 CHECKDUP means check for and avoid creating duplicate references
725 from the same insn. Such duplicates do no serious harm but
726 can slow life analysis. CHECKDUP is set only when duplicates
730 mark_label_ref (x, insn, checkdup)
734 register RTX_CODE code;
738 /* We can be called with NULL when scanning label_value_list. */
743 if (code == LABEL_REF)
745 register rtx label = XEXP (x, 0);
747 if (GET_CODE (label) != CODE_LABEL)
749 /* If the label was never emitted, this insn is junk,
750 but avoid a crash trying to refer to BLOCK_NUM (label).
751 This can happen as a result of a syntax error
752 and a diagnostic has already been printed. */
753 if (INSN_UID (label) == 0)
755 CONTAINING_INSN (x) = insn;
756 /* if CHECKDUP is set, check for duplicate ref from same insn
759 for (y = LABEL_REFS (label); y != label; y = LABEL_NEXTREF (y))
760 if (CONTAINING_INSN (y) == insn)
762 LABEL_NEXTREF (x) = LABEL_REFS (label);
763 LABEL_REFS (label) = x;
764 block_live_static[BLOCK_NUM (label)] = 1;
768 fmt = GET_RTX_FORMAT (code);
769 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
772 mark_label_ref (XEXP (x, i), insn, 0);
776 for (j = 0; j < XVECLEN (x, i); j++)
777 mark_label_ref (XVECEXP (x, i, j), insn, 1);
782 /* Determine which registers are live at the start of each
783 basic block of the function whose first insn is F.
784 NREGS is the number of registers used in F.
785 We allocate the vector basic_block_live_at_start
786 and the regsets that it points to, and fill them with the data.
787 regset_size and regset_bytes are also set here. */
790 life_analysis (f, nregs)
797 /* For each basic block, a bitmask of regs
798 live on exit from the block. */
799 regset *basic_block_live_at_end;
800 /* For each basic block, a bitmask of regs
801 live on entry to a successor-block of this block.
802 If this does not match basic_block_live_at_end,
803 that must be updated, and the block must be rescanned. */
804 regset *basic_block_new_live_at_end;
805 /* For each basic block, a bitmask of regs
806 whose liveness at the end of the basic block
807 can make a difference in which regs are live on entry to the block.
808 These are the regs that are set within the basic block,
809 possibly excluding those that are used after they are set. */
810 regset *basic_block_significant;
814 struct obstack flow_obstack;
816 gcc_obstack_init (&flow_obstack);
820 bzero (regs_ever_live, sizeof regs_ever_live);
822 /* Allocate and zero out many data structures
823 that will record the data from lifetime analysis. */
825 allocate_for_life_analysis ();
827 reg_next_use = (rtx *) alloca (nregs * sizeof (rtx));
828 bzero (reg_next_use, nregs * sizeof (rtx));
830 /* Set up several regset-vectors used internally within this function.
831 Their meanings are documented above, with their declarations. */
833 basic_block_live_at_end = (regset *) alloca (n_basic_blocks * sizeof (regset));
834 /* Don't use alloca since that leads to a crash rather than an error message
835 if there isn't enough space.
836 Don't use oballoc since we may need to allocate other things during
837 this function on the temporary obstack. */
838 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
839 bzero (tem, n_basic_blocks * regset_bytes);
840 init_regset_vector (basic_block_live_at_end, tem, n_basic_blocks, regset_bytes);
842 basic_block_new_live_at_end = (regset *) alloca (n_basic_blocks * sizeof (regset));
843 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
844 bzero (tem, n_basic_blocks * regset_bytes);
845 init_regset_vector (basic_block_new_live_at_end, tem, n_basic_blocks, regset_bytes);
847 basic_block_significant = (regset *) alloca (n_basic_blocks * sizeof (regset));
848 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
849 bzero (tem, n_basic_blocks * regset_bytes);
850 init_regset_vector (basic_block_significant, tem, n_basic_blocks, regset_bytes);
852 /* Record which insns refer to any volatile memory
853 or for any reason can't be deleted just because they are dead stores.
854 Also, delete any insns that copy a register to itself. */
856 for (insn = f; insn; insn = NEXT_INSN (insn))
858 enum rtx_code code1 = GET_CODE (insn);
859 if (code1 == CALL_INSN)
860 INSN_VOLATILE (insn) = 1;
861 else if (code1 == INSN || code1 == JUMP_INSN)
863 /* Delete (in effect) any obvious no-op moves. */
864 if (GET_CODE (PATTERN (insn)) == SET
865 && GET_CODE (SET_DEST (PATTERN (insn))) == REG
866 && GET_CODE (SET_SRC (PATTERN (insn))) == REG
867 && REGNO (SET_DEST (PATTERN (insn))) ==
868 REGNO (SET_SRC (PATTERN (insn)))
869 /* Insns carrying these notes are useful later on. */
870 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
872 PUT_CODE (insn, NOTE);
873 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
874 NOTE_SOURCE_FILE (insn) = 0;
876 else if (GET_CODE (PATTERN (insn)) == PARALLEL)
878 /* If nothing but SETs of registers to themselves,
879 this insn can also be deleted. */
880 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
882 rtx tem = XVECEXP (PATTERN (insn), 0, i);
884 if (GET_CODE (tem) == USE
885 || GET_CODE (tem) == CLOBBER)
888 if (GET_CODE (tem) != SET
889 || GET_CODE (SET_DEST (tem)) != REG
890 || GET_CODE (SET_SRC (tem)) != REG
891 || REGNO (SET_DEST (tem)) != REGNO (SET_SRC (tem)))
895 if (i == XVECLEN (PATTERN (insn), 0)
896 /* Insns carrying these notes are useful later on. */
897 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
899 PUT_CODE (insn, NOTE);
900 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
901 NOTE_SOURCE_FILE (insn) = 0;
904 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
906 else if (GET_CODE (PATTERN (insn)) != USE)
907 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
908 /* A SET that makes space on the stack cannot be dead.
909 (Such SETs occur only for allocating variable-size data,
910 so they will always have a PLUS or MINUS according to the
911 direction of stack growth.)
912 Even if this function never uses this stack pointer value,
913 signal handlers do! */
914 else if (code1 == INSN && GET_CODE (PATTERN (insn)) == SET
915 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
916 #ifdef STACK_GROWS_DOWNWARD
917 && GET_CODE (SET_SRC (PATTERN (insn))) == MINUS
919 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
921 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx)
922 INSN_VOLATILE (insn) = 1;
926 if (n_basic_blocks > 0)
927 #ifdef EXIT_IGNORE_STACK
928 if (! EXIT_IGNORE_STACK
929 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
932 /* If exiting needs the right stack value,
933 consider the stack pointer live at the end of the function. */
934 basic_block_live_at_end[n_basic_blocks - 1]
935 [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
936 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
937 basic_block_new_live_at_end[n_basic_blocks - 1]
938 [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
939 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
942 /* Mark the frame pointer is needed at the end of the function. If
943 we end up eliminating it, it will be removed from the live list
944 of each basic block by reload. */
946 if (n_basic_blocks > 0)
948 basic_block_live_at_end[n_basic_blocks - 1]
949 [FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
950 |= (REGSET_ELT_TYPE) 1 << (FRAME_POINTER_REGNUM % REGSET_ELT_BITS);
951 basic_block_new_live_at_end[n_basic_blocks - 1]
952 [FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
953 |= (REGSET_ELT_TYPE) 1 << (FRAME_POINTER_REGNUM % REGSET_ELT_BITS);
954 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
955 /* If they are different, also mark the hard frame pointer as live */
956 basic_block_live_at_end[n_basic_blocks - 1]
957 [HARD_FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
958 |= (REGSET_ELT_TYPE) 1 << (HARD_FRAME_POINTER_REGNUM
960 basic_block_new_live_at_end[n_basic_blocks - 1]
961 [HARD_FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
962 |= (REGSET_ELT_TYPE) 1 << (HARD_FRAME_POINTER_REGNUM
967 /* Mark all global registers as being live at the end of the function
968 since they may be referenced by our caller. */
970 if (n_basic_blocks > 0)
971 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
974 basic_block_live_at_end[n_basic_blocks - 1]
975 [i / REGSET_ELT_BITS]
976 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
977 basic_block_new_live_at_end[n_basic_blocks - 1]
978 [i / REGSET_ELT_BITS]
979 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
982 /* Propagate life info through the basic blocks
983 around the graph of basic blocks.
985 This is a relaxation process: each time a new register
986 is live at the end of the basic block, we must scan the block
987 to determine which registers are, as a consequence, live at the beginning
988 of that block. These registers must then be marked live at the ends
989 of all the blocks that can transfer control to that block.
990 The process continues until it reaches a fixed point. */
997 for (i = n_basic_blocks - 1; i >= 0; i--)
999 int consider = first_pass;
1000 int must_rescan = first_pass;
1005 /* Set CONSIDER if this block needs thinking about at all
1006 (that is, if the regs live now at the end of it
1007 are not the same as were live at the end of it when
1008 we last thought about it).
1009 Set must_rescan if it needs to be thought about
1010 instruction by instruction (that is, if any additional
1011 reg that is live at the end now but was not live there before
1012 is one of the significant regs of this basic block). */
1014 for (j = 0; j < regset_size; j++)
1016 register REGSET_ELT_TYPE x
1017 = (basic_block_new_live_at_end[i][j]
1018 & ~basic_block_live_at_end[i][j]);
1021 if (x & basic_block_significant[i][j])
1033 /* The live_at_start of this block may be changing,
1034 so another pass will be required after this one. */
1039 /* No complete rescan needed;
1040 just record those variables newly known live at end
1041 as live at start as well. */
1042 for (j = 0; j < regset_size; j++)
1044 register REGSET_ELT_TYPE x
1045 = (basic_block_new_live_at_end[i][j]
1046 & ~basic_block_live_at_end[i][j]);
1047 basic_block_live_at_start[i][j] |= x;
1048 basic_block_live_at_end[i][j] |= x;
1053 /* Update the basic_block_live_at_start
1054 by propagation backwards through the block. */
1055 bcopy (basic_block_new_live_at_end[i],
1056 basic_block_live_at_end[i], regset_bytes);
1057 bcopy (basic_block_live_at_end[i],
1058 basic_block_live_at_start[i], regset_bytes);
1059 propagate_block (basic_block_live_at_start[i],
1060 basic_block_head[i], basic_block_end[i], 0,
1061 first_pass ? basic_block_significant[i]
1067 register rtx jump, head;
1068 /* Update the basic_block_new_live_at_end's of the block
1069 that falls through into this one (if any). */
1070 head = basic_block_head[i];
1071 jump = PREV_INSN (head);
1072 if (basic_block_drops_in[i])
1074 register int from_block = BLOCK_NUM (jump);
1076 for (j = 0; j < regset_size; j++)
1077 basic_block_new_live_at_end[from_block][j]
1078 |= basic_block_live_at_start[i][j];
1080 /* Update the basic_block_new_live_at_end's of
1081 all the blocks that jump to this one. */
1082 if (GET_CODE (head) == CODE_LABEL)
1083 for (jump = LABEL_REFS (head);
1085 jump = LABEL_NEXTREF (jump))
1087 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
1089 for (j = 0; j < regset_size; j++)
1090 basic_block_new_live_at_end[from_block][j]
1091 |= basic_block_live_at_start[i][j];
1101 /* The only pseudos that are live at the beginning of the function are
1102 those that were not set anywhere in the function. local-alloc doesn't
1103 know how to handle these correctly, so mark them as not local to any
1106 if (n_basic_blocks > 0)
1107 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
1108 if (basic_block_live_at_start[0][i / REGSET_ELT_BITS]
1109 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
1110 reg_basic_block[i] = REG_BLOCK_GLOBAL;
1112 /* Now the life information is accurate.
1113 Make one more pass over each basic block
1114 to delete dead stores, create autoincrement addressing
1115 and record how many times each register is used, is set, or dies.
1117 To save time, we operate directly in basic_block_live_at_end[i],
1118 thus destroying it (in fact, converting it into a copy of
1119 basic_block_live_at_start[i]). This is ok now because
1120 basic_block_live_at_end[i] is no longer used past this point. */
1124 for (i = 0; i < n_basic_blocks; i++)
1126 propagate_block (basic_block_live_at_end[i],
1127 basic_block_head[i], basic_block_end[i], 1,
1135 /* Something live during a setjmp should not be put in a register
1136 on certain machines which restore regs from stack frames
1137 rather than from the jmpbuf.
1138 But we don't need to do this for the user's variables, since
1139 ANSI says only volatile variables need this. */
1140 #ifdef LONGJMP_RESTORE_FROM_STACK
1141 for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1142 if (regs_live_at_setjmp[i / REGSET_ELT_BITS]
1143 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS))
1144 && regno_reg_rtx[i] != 0 && ! REG_USERVAR_P (regno_reg_rtx[i]))
1146 reg_live_length[i] = -1;
1147 reg_basic_block[i] = -1;
1152 /* We have a problem with any pseudoreg that
1153 lives across the setjmp. ANSI says that if a
1154 user variable does not change in value
1155 between the setjmp and the longjmp, then the longjmp preserves it.
1156 This includes longjmp from a place where the pseudo appears dead.
1157 (In principle, the value still exists if it is in scope.)
1158 If the pseudo goes in a hard reg, some other value may occupy
1159 that hard reg where this pseudo is dead, thus clobbering the pseudo.
1160 Conclusion: such a pseudo must not go in a hard reg. */
1161 for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1162 if ((regs_live_at_setjmp[i / REGSET_ELT_BITS]
1163 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
1164 && regno_reg_rtx[i] != 0)
1166 reg_live_length[i] = -1;
1167 reg_basic_block[i] = -1;
1170 obstack_free (&flow_obstack, NULL_PTR);
1173 /* Subroutines of life analysis. */
1175 /* Allocate the permanent data structures that represent the results
1176 of life analysis. Not static since used also for stupid life analysis. */
1179 allocate_for_life_analysis ()
1182 register regset tem;
1184 regset_size = ((max_regno + REGSET_ELT_BITS - 1) / REGSET_ELT_BITS);
1185 regset_bytes = regset_size * sizeof (*(regset)0);
1187 reg_n_refs = (int *) oballoc (max_regno * sizeof (int));
1188 bzero (reg_n_refs, max_regno * sizeof (int));
1190 reg_n_sets = (short *) oballoc (max_regno * sizeof (short));
1191 bzero (reg_n_sets, max_regno * sizeof (short));
1193 reg_n_deaths = (short *) oballoc (max_regno * sizeof (short));
1194 bzero (reg_n_deaths, max_regno * sizeof (short));
1196 reg_live_length = (int *) oballoc (max_regno * sizeof (int));
1197 bzero (reg_live_length, max_regno * sizeof (int));
1199 reg_n_calls_crossed = (int *) oballoc (max_regno * sizeof (int));
1200 bzero (reg_n_calls_crossed, max_regno * sizeof (int));
1202 reg_basic_block = (int *) oballoc (max_regno * sizeof (int));
1203 for (i = 0; i < max_regno; i++)
1204 reg_basic_block[i] = REG_BLOCK_UNKNOWN;
1206 basic_block_live_at_start = (regset *) oballoc (n_basic_blocks * sizeof (regset));
1207 tem = (regset) oballoc (n_basic_blocks * regset_bytes);
1208 bzero (tem, n_basic_blocks * regset_bytes);
1209 init_regset_vector (basic_block_live_at_start, tem, n_basic_blocks, regset_bytes);
1211 regs_live_at_setjmp = (regset) oballoc (regset_bytes);
1212 bzero (regs_live_at_setjmp, regset_bytes);
1215 /* Make each element of VECTOR point at a regset,
1216 taking the space for all those regsets from SPACE.
1217 SPACE is of type regset, but it is really as long as NELTS regsets.
1218 BYTES_PER_ELT is the number of bytes in one regset. */
1221 init_regset_vector (vector, space, nelts, bytes_per_elt)
1228 register regset p = space;
1230 for (i = 0; i < nelts; i++)
1233 p += bytes_per_elt / sizeof (*p);
1237 /* Compute the registers live at the beginning of a basic block
1238 from those live at the end.
1240 When called, OLD contains those live at the end.
1241 On return, it contains those live at the beginning.
1242 FIRST and LAST are the first and last insns of the basic block.
1244 FINAL is nonzero if we are doing the final pass which is not
1245 for computing the life info (since that has already been done)
1246 but for acting on it. On this pass, we delete dead stores,
1247 set up the logical links and dead-variables lists of instructions,
1248 and merge instructions for autoincrement and autodecrement addresses.
1250 SIGNIFICANT is nonzero only the first time for each basic block.
1251 If it is nonzero, it points to a regset in which we store
1252 a 1 for each register that is set within the block.
1254 BNUM is the number of the basic block. */
1257 propagate_block (old, first, last, final, significant, bnum)
1258 register regset old;
1270 /* The following variables are used only if FINAL is nonzero. */
1271 /* This vector gets one element for each reg that has been live
1272 at any point in the basic block that has been scanned so far.
1273 SOMETIMES_MAX says how many elements are in use so far.
1274 In each element, OFFSET is the byte-number within a regset
1275 for the register described by the element, and BIT is a mask
1276 for that register's bit within the byte. */
1277 register struct sometimes { short offset; short bit; } *regs_sometimes_live;
1278 int sometimes_max = 0;
1279 /* This regset has 1 for each reg that we have seen live so far.
1280 It and REGS_SOMETIMES_LIVE are updated together. */
1283 /* The loop depth may change in the middle of a basic block. Since we
1284 scan from end to beginning, we start with the depth at the end of the
1285 current basic block, and adjust as we pass ends and starts of loops. */
1286 loop_depth = basic_block_loop_depth[bnum];
1288 dead = (regset) alloca (regset_bytes);
1289 live = (regset) alloca (regset_bytes);
1294 /* Include any notes at the end of the block in the scan.
1295 This is in case the block ends with a call to setjmp. */
1297 while (NEXT_INSN (last) != 0 && GET_CODE (NEXT_INSN (last)) == NOTE)
1299 /* Look for loop boundaries, we are going forward here. */
1300 last = NEXT_INSN (last);
1301 if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_BEG)
1303 else if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_END)
1309 register int i, offset;
1310 REGSET_ELT_TYPE bit;
1313 maxlive = (regset) alloca (regset_bytes);
1314 bcopy (old, maxlive, regset_bytes);
1316 = (struct sometimes *) alloca (max_regno * sizeof (struct sometimes));
1318 /* Process the regs live at the end of the block.
1319 Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
1320 Also mark them as not local to any one basic block. */
1322 for (offset = 0, i = 0; offset < regset_size; offset++)
1323 for (bit = 1; bit; bit <<= 1, i++)
1327 if (old[offset] & bit)
1329 reg_basic_block[i] = REG_BLOCK_GLOBAL;
1330 regs_sometimes_live[sometimes_max].offset = offset;
1331 regs_sometimes_live[sometimes_max].bit = i % REGSET_ELT_BITS;
1337 /* Scan the block an insn at a time from end to beginning. */
1339 for (insn = last; ; insn = prev)
1341 prev = PREV_INSN (insn);
1343 /* Look for loop boundaries, remembering that we are going backwards. */
1344 if (GET_CODE (insn) == NOTE
1345 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1347 else if (GET_CODE (insn) == NOTE
1348 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1351 /* If we have LOOP_DEPTH == 0, there has been a bookkeeping error.
1352 Abort now rather than setting register status incorrectly. */
1353 if (loop_depth == 0)
1356 /* If this is a call to `setjmp' et al,
1357 warn if any non-volatile datum is live. */
1359 if (final && GET_CODE (insn) == NOTE
1360 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
1363 for (i = 0; i < regset_size; i++)
1364 regs_live_at_setjmp[i] |= old[i];
1367 /* Update the life-status of regs for this insn.
1368 First DEAD gets which regs are set in this insn
1369 then LIVE gets which regs are used in this insn.
1370 Then the regs live before the insn
1371 are those live after, with DEAD regs turned off,
1372 and then LIVE regs turned on. */
1374 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
1377 rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1379 = (insn_dead_p (PATTERN (insn), old, 0)
1380 /* Don't delete something that refers to volatile storage! */
1381 && ! INSN_VOLATILE (insn));
1383 = (insn_is_dead && note != 0
1384 && libcall_dead_p (PATTERN (insn), old, note, insn));
1386 /* If an instruction consists of just dead store(s) on final pass,
1387 "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
1388 We could really delete it with delete_insn, but that
1389 can cause trouble for first or last insn in a basic block. */
1390 if (final && insn_is_dead)
1392 PUT_CODE (insn, NOTE);
1393 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
1394 NOTE_SOURCE_FILE (insn) = 0;
1396 /* CC0 is now known to be dead. Either this insn used it,
1397 in which case it doesn't anymore, or clobbered it,
1398 so the next insn can't use it. */
1401 /* If this insn is copying the return value from a library call,
1402 delete the entire library call. */
1403 if (libcall_is_dead)
1405 rtx first = XEXP (note, 0);
1407 while (INSN_DELETED_P (first))
1408 first = NEXT_INSN (first);
1413 NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED;
1414 NOTE_SOURCE_FILE (p) = 0;
1420 for (i = 0; i < regset_size; i++)
1422 dead[i] = 0; /* Faster than bzero here */
1423 live[i] = 0; /* since regset_size is usually small */
1426 /* See if this is an increment or decrement that can be
1427 merged into a following memory address. */
1430 register rtx x = PATTERN (insn);
1431 /* Does this instruction increment or decrement a register? */
1432 if (final && GET_CODE (x) == SET
1433 && GET_CODE (SET_DEST (x)) == REG
1434 && (GET_CODE (SET_SRC (x)) == PLUS
1435 || GET_CODE (SET_SRC (x)) == MINUS)
1436 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1437 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1438 /* Ok, look for a following memory ref we can combine with.
1439 If one is found, change the memory ref to a PRE_INC
1440 or PRE_DEC, cancel this insn, and return 1.
1441 Return 0 if nothing has been done. */
1442 && try_pre_increment_1 (insn))
1445 #endif /* AUTO_INC_DEC */
1447 /* If this is not the final pass, and this insn is copying the
1448 value of a library call and it's dead, don't scan the
1449 insns that perform the library call, so that the call's
1450 arguments are not marked live. */
1451 if (libcall_is_dead)
1453 /* Mark the dest reg as `significant'. */
1454 mark_set_regs (old, dead, PATTERN (insn), NULL_RTX, significant);
1456 insn = XEXP (note, 0);
1457 prev = PREV_INSN (insn);
1459 else if (GET_CODE (PATTERN (insn)) == SET
1460 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1461 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1462 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1463 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1464 /* We have an insn to pop a constant amount off the stack.
1465 (Such insns use PLUS regardless of the direction of the stack,
1466 and any insn to adjust the stack by a constant is always a pop.)
1467 These insns, if not dead stores, have no effect on life. */
1471 /* LIVE gets the regs used in INSN;
1472 DEAD gets those set by it. Dead insns don't make anything
1475 mark_set_regs (old, dead, PATTERN (insn),
1476 final ? insn : NULL_RTX, significant);
1478 /* If an insn doesn't use CC0, it becomes dead since we
1479 assume that every insn clobbers it. So show it dead here;
1480 mark_used_regs will set it live if it is referenced. */
1484 mark_used_regs (old, live, PATTERN (insn), final, insn);
1486 /* Sometimes we may have inserted something before INSN (such as
1487 a move) when we make an auto-inc. So ensure we will scan
1490 prev = PREV_INSN (insn);
1493 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1497 /* Each call clobbers all call-clobbered regs that are not
1498 global. Note that the function-value reg is a
1499 call-clobbered reg, and mark_set_regs has already had
1500 a chance to handle it. */
1502 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1503 if (call_used_regs[i] && ! global_regs[i])
1504 dead[i / REGSET_ELT_BITS]
1505 |= ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS));
1507 /* The stack ptr is used (honorarily) by a CALL insn. */
1508 live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
1509 |= ((REGSET_ELT_TYPE) 1
1510 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS));
1512 /* Calls may also reference any of the global registers,
1513 so they are made live. */
1515 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1517 live[i / REGSET_ELT_BITS]
1518 |= ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS));
1520 /* Calls also clobber memory. */
1524 /* Update OLD for the registers used or set. */
1525 for (i = 0; i < regset_size; i++)
1531 if (GET_CODE (insn) == CALL_INSN && final)
1533 /* Any regs live at the time of a call instruction
1534 must not go in a register clobbered by calls.
1535 Find all regs now live and record this for them. */
1537 register struct sometimes *p = regs_sometimes_live;
1539 for (i = 0; i < sometimes_max; i++, p++)
1540 if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
1541 reg_n_calls_crossed[p->offset * REGSET_ELT_BITS + p->bit]+= 1;
1545 /* On final pass, add any additional sometimes-live regs
1546 into MAXLIVE and REGS_SOMETIMES_LIVE.
1547 Also update counts of how many insns each reg is live at. */
1551 for (i = 0; i < regset_size; i++)
1553 register REGSET_ELT_TYPE diff = live[i] & ~maxlive[i];
1559 for (regno = 0; diff && regno < REGSET_ELT_BITS; regno++)
1560 if (diff & ((REGSET_ELT_TYPE) 1 << regno))
1562 regs_sometimes_live[sometimes_max].offset = i;
1563 regs_sometimes_live[sometimes_max].bit = regno;
1564 diff &= ~ ((REGSET_ELT_TYPE) 1 << regno);
1571 register struct sometimes *p = regs_sometimes_live;
1572 for (i = 0; i < sometimes_max; i++, p++)
1574 if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
1575 reg_live_length[p->offset * REGSET_ELT_BITS + p->bit]++;
1585 if (num_scratch > max_scratch)
1586 max_scratch = num_scratch;
1589 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1590 (SET expressions whose destinations are registers dead after the insn).
1591 NEEDED is the regset that says which regs are alive after the insn.
1593 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */
1596 insn_dead_p (x, needed, call_ok)
1601 register RTX_CODE code = GET_CODE (x);
1602 /* If setting something that's a reg or part of one,
1603 see if that register's altered value will be live. */
1607 register rtx r = SET_DEST (x);
1608 /* A SET that is a subroutine call cannot be dead. */
1609 if (! call_ok && GET_CODE (SET_SRC (x)) == CALL)
1613 if (GET_CODE (r) == CC0)
1617 if (GET_CODE (r) == MEM && last_mem_set && ! MEM_VOLATILE_P (r)
1618 && rtx_equal_p (r, last_mem_set))
1621 while (GET_CODE (r) == SUBREG
1622 || GET_CODE (r) == STRICT_LOW_PART
1623 || GET_CODE (r) == ZERO_EXTRACT
1624 || GET_CODE (r) == SIGN_EXTRACT)
1627 if (GET_CODE (r) == REG)
1629 register int regno = REGNO (r);
1630 register int offset = regno / REGSET_ELT_BITS;
1631 register REGSET_ELT_TYPE bit
1632 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
1634 /* Don't delete insns to set global regs. */
1635 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
1636 /* Make sure insns to set frame pointer aren't deleted. */
1637 || regno == FRAME_POINTER_REGNUM
1638 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1639 || regno == HARD_FRAME_POINTER_REGNUM
1641 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1642 /* Make sure insns to set arg pointer are never deleted
1643 (if the arg pointer isn't fixed, there will be a USE for
1644 it, so we can treat it normally). */
1645 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1647 || (needed[offset] & bit) != 0)
1650 /* If this is a hard register, verify that subsequent words are
1652 if (regno < FIRST_PSEUDO_REGISTER)
1654 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
1657 if ((needed[(regno + n) / REGSET_ELT_BITS]
1658 & ((REGSET_ELT_TYPE) 1
1659 << ((regno + n) % REGSET_ELT_BITS))) != 0)
1666 /* If performing several activities,
1667 insn is dead if each activity is individually dead.
1668 Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
1669 that's inside a PARALLEL doesn't make the insn worth keeping. */
1670 else if (code == PARALLEL)
1672 register int i = XVECLEN (x, 0);
1673 for (i--; i >= 0; i--)
1675 rtx elt = XVECEXP (x, 0, i);
1676 if (!insn_dead_p (elt, needed, call_ok)
1677 && GET_CODE (elt) != CLOBBER
1678 && GET_CODE (elt) != USE)
1683 /* We do not check CLOBBER or USE here.
1684 An insn consisting of just a CLOBBER or just a USE
1685 should not be deleted. */
1689 /* If X is the pattern of the last insn in a libcall, and assuming X is dead,
1690 return 1 if the entire library call is dead.
1691 This is true if X copies a register (hard or pseudo)
1692 and if the hard return reg of the call insn is dead.
1693 (The caller should have tested the destination of X already for death.)
1695 If this insn doesn't just copy a register, then we don't
1696 have an ordinary libcall. In that case, cse could not have
1697 managed to substitute the source for the dest later on,
1698 so we can assume the libcall is dead.
1700 NEEDED is the bit vector of pseudoregs live before this insn.
1701 NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
1704 libcall_dead_p (x, needed, note, insn)
1710 register RTX_CODE code = GET_CODE (x);
1714 register rtx r = SET_SRC (x);
1715 if (GET_CODE (r) == REG)
1717 rtx call = XEXP (note, 0);
1720 /* Find the call insn. */
1721 while (call != insn && GET_CODE (call) != CALL_INSN)
1722 call = NEXT_INSN (call);
1724 /* If there is none, do nothing special,
1725 since ordinary death handling can understand these insns. */
1729 /* See if the hard reg holding the value is dead.
1730 If this is a PARALLEL, find the call within it. */
1731 call = PATTERN (call);
1732 if (GET_CODE (call) == PARALLEL)
1734 for (i = XVECLEN (call, 0) - 1; i >= 0; i--)
1735 if (GET_CODE (XVECEXP (call, 0, i)) == SET
1736 && GET_CODE (SET_SRC (XVECEXP (call, 0, i))) == CALL)
1742 call = XVECEXP (call, 0, i);
1745 return insn_dead_p (call, needed, 1);
1751 /* Return 1 if register REGNO was used before it was set.
1752 In other words, if it is live at function entry.
1753 Don't count global regster variables, though. */
1756 regno_uninitialized (regno)
1759 if (n_basic_blocks == 0
1760 || (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
1763 return (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1764 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS)));
1767 /* 1 if register REGNO was alive at a place where `setjmp' was called
1768 and was set more than once or is an argument.
1769 Such regs may be clobbered by `longjmp'. */
1772 regno_clobbered_at_setjmp (regno)
1775 if (n_basic_blocks == 0)
1778 return ((reg_n_sets[regno] > 1
1779 || (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1780 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))))
1781 && (regs_live_at_setjmp[regno / REGSET_ELT_BITS]
1782 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))));
1785 /* Process the registers that are set within X.
1786 Their bits are set to 1 in the regset DEAD,
1787 because they are dead prior to this insn.
1789 If INSN is nonzero, it is the insn being processed
1790 and the fact that it is nonzero implies this is the FINAL pass
1791 in propagate_block. In this case, various info about register
1792 usage is stored, LOG_LINKS fields of insns are set up. */
1795 mark_set_regs (needed, dead, x, insn, significant)
1802 register RTX_CODE code = GET_CODE (x);
1804 if (code == SET || code == CLOBBER)
1805 mark_set_1 (needed, dead, x, insn, significant);
1806 else if (code == PARALLEL)
1809 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
1811 code = GET_CODE (XVECEXP (x, 0, i));
1812 if (code == SET || code == CLOBBER)
1813 mark_set_1 (needed, dead, XVECEXP (x, 0, i), insn, significant);
1818 /* Process a single SET rtx, X. */
1821 mark_set_1 (needed, dead, x, insn, significant)
1829 register rtx reg = SET_DEST (x);
1831 /* Modifying just one hardware register of a multi-reg value
1832 or just a byte field of a register
1833 does not mean the value from before this insn is now dead.
1834 But it does mean liveness of that register at the end of the block
1837 Within mark_set_1, however, we treat it as if the register is
1838 indeed modified. mark_used_regs will, however, also treat this
1839 register as being used. Thus, we treat these insns as setting a
1840 new value for the register as a function of its old value. This
1841 cases LOG_LINKS to be made appropriately and this will help combine. */
1843 while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
1844 || GET_CODE (reg) == SIGN_EXTRACT
1845 || GET_CODE (reg) == STRICT_LOW_PART)
1846 reg = XEXP (reg, 0);
1848 /* If we are writing into memory or into a register mentioned in the
1849 address of the last thing stored into memory, show we don't know
1850 what the last store was. If we are writing memory, save the address
1851 unless it is volatile. */
1852 if (GET_CODE (reg) == MEM
1853 || (GET_CODE (reg) == REG
1854 && last_mem_set != 0 && reg_overlap_mentioned_p (reg, last_mem_set)))
1857 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
1858 /* There are no REG_INC notes for SP, so we can't assume we'll see
1859 everything that invalidates it. To be safe, don't eliminate any
1860 stores though SP; none of them should be redundant anyway. */
1861 && ! reg_mentioned_p (stack_pointer_rtx, reg))
1864 if (GET_CODE (reg) == REG
1865 && (regno = REGNO (reg), regno != FRAME_POINTER_REGNUM)
1866 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1867 && regno != HARD_FRAME_POINTER_REGNUM
1869 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1870 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1872 && ! (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
1873 /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
1875 register int offset = regno / REGSET_ELT_BITS;
1876 register REGSET_ELT_TYPE bit
1877 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
1878 REGSET_ELT_TYPE all_needed = (needed[offset] & bit);
1879 REGSET_ELT_TYPE some_needed = (needed[offset] & bit);
1881 /* Mark it as a significant register for this basic block. */
1883 significant[offset] |= bit;
1885 /* Mark it as as dead before this insn. */
1886 dead[offset] |= bit;
1888 /* A hard reg in a wide mode may really be multiple registers.
1889 If so, mark all of them just like the first. */
1890 if (regno < FIRST_PSEUDO_REGISTER)
1894 /* Nothing below is needed for the stack pointer; get out asap.
1895 Eg, log links aren't needed, since combine won't use them. */
1896 if (regno == STACK_POINTER_REGNUM)
1899 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
1903 significant[(regno + n) / REGSET_ELT_BITS]
1904 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
1905 dead[(regno + n) / REGSET_ELT_BITS]
1906 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
1908 |= (needed[(regno + n) / REGSET_ELT_BITS]
1909 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
1911 &= (needed[(regno + n) / REGSET_ELT_BITS]
1912 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
1915 /* Additional data to record if this is the final pass. */
1918 register rtx y = reg_next_use[regno];
1919 register int blocknum = BLOCK_NUM (insn);
1921 /* The next use is no longer "next", since a store intervenes. */
1922 reg_next_use[regno] = 0;
1924 /* If this is a hard reg, record this function uses the reg. */
1926 if (regno < FIRST_PSEUDO_REGISTER)
1929 int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg));
1931 for (i = regno; i < endregno; i++)
1933 regs_ever_live[i] = 1;
1939 /* Keep track of which basic blocks each reg appears in. */
1941 if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
1942 reg_basic_block[regno] = blocknum;
1943 else if (reg_basic_block[regno] != blocknum)
1944 reg_basic_block[regno] = REG_BLOCK_GLOBAL;
1946 /* Count (weighted) references, stores, etc. This counts a
1947 register twice if it is modified, but that is correct. */
1948 reg_n_sets[regno]++;
1950 reg_n_refs[regno] += loop_depth;
1952 /* The insns where a reg is live are normally counted
1953 elsewhere, but we want the count to include the insn
1954 where the reg is set, and the normal counting mechanism
1955 would not count it. */
1956 reg_live_length[regno]++;
1961 /* Make a logical link from the next following insn
1962 that uses this register, back to this insn.
1963 The following insns have already been processed.
1965 We don't build a LOG_LINK for hard registers containing
1966 in ASM_OPERANDs. If these registers get replaced,
1967 we might wind up changing the semantics of the insn,
1968 even if reload can make what appear to be valid assignments
1970 if (y && (BLOCK_NUM (y) == blocknum)
1971 && (regno >= FIRST_PSEUDO_REGISTER
1972 || asm_noperands (PATTERN (y)) < 0))
1974 = gen_rtx (INSN_LIST, VOIDmode, insn, LOG_LINKS (y));
1976 else if (! some_needed)
1978 /* Note that dead stores have already been deleted when possible
1979 If we get here, we have found a dead store that cannot
1980 be eliminated (because the same insn does something useful).
1981 Indicate this by marking the reg being set as dying here. */
1983 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
1984 reg_n_deaths[REGNO (reg)]++;
1988 /* This is a case where we have a multi-word hard register
1989 and some, but not all, of the words of the register are
1990 needed in subsequent insns. Write REG_UNUSED notes
1991 for those parts that were not needed. This case should
1996 for (i = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1;
1998 if ((needed[(regno + i) / REGSET_ELT_BITS]
1999 & ((REGSET_ELT_TYPE) 1
2000 << ((regno + i) % REGSET_ELT_BITS))) == 0)
2002 = gen_rtx (EXPR_LIST, REG_UNUSED,
2003 gen_rtx (REG, word_mode, regno + i),
2008 else if (GET_CODE (reg) == REG)
2009 reg_next_use[regno] = 0;
2011 /* If this is the last pass and this is a SCRATCH, show it will be dying
2012 here and count it. */
2013 else if (GET_CODE (reg) == SCRATCH && insn != 0)
2016 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
2023 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
2027 find_auto_inc (needed, x, insn)
2032 rtx addr = XEXP (x, 0);
2033 HOST_WIDE_INT offset = 0;
2036 /* Here we detect use of an index register which might be good for
2037 postincrement, postdecrement, preincrement, or predecrement. */
2039 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
2040 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
2042 if (GET_CODE (addr) == REG)
2045 register int size = GET_MODE_SIZE (GET_MODE (x));
2048 int regno = REGNO (addr);
2050 /* Is the next use an increment that might make auto-increment? */
2051 if ((incr = reg_next_use[regno]) != 0
2052 && (set = single_set (incr)) != 0
2053 && GET_CODE (set) == SET
2054 && BLOCK_NUM (incr) == BLOCK_NUM (insn)
2055 /* Can't add side effects to jumps; if reg is spilled and
2056 reloaded, there's no way to store back the altered value. */
2057 && GET_CODE (insn) != JUMP_INSN
2058 && (y = SET_SRC (set), GET_CODE (y) == PLUS)
2059 && XEXP (y, 0) == addr
2060 && GET_CODE (XEXP (y, 1)) == CONST_INT
2062 #ifdef HAVE_POST_INCREMENT
2063 || (INTVAL (XEXP (y, 1)) == size && offset == 0)
2065 #ifdef HAVE_POST_DECREMENT
2066 || (INTVAL (XEXP (y, 1)) == - size && offset == 0)
2068 #ifdef HAVE_PRE_INCREMENT
2069 || (INTVAL (XEXP (y, 1)) == size && offset == size)
2071 #ifdef HAVE_PRE_DECREMENT
2072 || (INTVAL (XEXP (y, 1)) == - size && offset == - size)
2075 /* Make sure this reg appears only once in this insn. */
2076 && (use = find_use_as_address (PATTERN (insn), addr, offset),
2077 use != 0 && use != (rtx) 1))
2080 rtx q = SET_DEST (set);
2082 if (dead_or_set_p (incr, addr))
2084 else if (GET_CODE (q) == REG
2085 /* PREV_INSN used here to check the semi-open interval
2087 && ! reg_used_between_p (q, PREV_INSN (insn), incr))
2089 /* We have *p followed sometime later by q = p+size.
2090 Both p and q must be live afterward,
2091 and q is not used between INSN and it's assignment.
2092 Change it to q = p, ...*q..., q = q+size.
2093 Then fall into the usual case. */
2097 emit_move_insn (q, addr);
2098 insns = get_insns ();
2101 /* If anything in INSNS have UID's that don't fit within the
2102 extra space we allocate earlier, we can't make this auto-inc.
2103 This should never happen. */
2104 for (temp = insns; temp; temp = NEXT_INSN (temp))
2106 if (INSN_UID (temp) > max_uid_for_flow)
2108 BLOCK_NUM (temp) = BLOCK_NUM (insn);
2111 emit_insns_before (insns, insn);
2113 if (basic_block_head[BLOCK_NUM (insn)] == insn)
2114 basic_block_head[BLOCK_NUM (insn)] = insns;
2119 /* INCR will become a NOTE and INSN won't contain a
2120 use of ADDR. If a use of ADDR was just placed in
2121 the insn before INSN, make that the next use.
2122 Otherwise, invalidate it. */
2123 if (GET_CODE (PREV_INSN (insn)) == INSN
2124 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
2125 && SET_SRC (PATTERN (PREV_INSN (insn))) == addr)
2126 reg_next_use[regno] = PREV_INSN (insn);
2128 reg_next_use[regno] = 0;
2134 /* REGNO is now used in INCR which is below INSN, but
2135 it previously wasn't live here. If we don't mark
2136 it as needed, we'll put a REG_DEAD note for it
2137 on this insn, which is incorrect. */
2138 needed[regno / REGSET_ELT_BITS]
2139 |= (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2141 /* If there are any calls between INSN and INCR, show
2142 that REGNO now crosses them. */
2143 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
2144 if (GET_CODE (temp) == CALL_INSN)
2145 reg_n_calls_crossed[regno]++;
2150 /* We have found a suitable auto-increment: do POST_INC around
2151 the register here, and patch out the increment instruction
2153 XEXP (x, 0) = gen_rtx ((INTVAL (XEXP (y, 1)) == size
2154 ? (offset ? PRE_INC : POST_INC)
2155 : (offset ? PRE_DEC : POST_DEC)),
2158 /* Record that this insn has an implicit side effect. */
2160 = gen_rtx (EXPR_LIST, REG_INC, addr, REG_NOTES (insn));
2162 /* Modify the old increment-insn to simply copy
2163 the already-incremented value of our register. */
2164 SET_SRC (set) = addr;
2165 /* Indicate insn must be re-recognized. */
2166 INSN_CODE (incr) = -1;
2168 /* If that makes it a no-op (copying the register into itself)
2169 then delete it so it won't appear to be a "use" and a "set"
2170 of this register. */
2171 if (SET_DEST (set) == addr)
2173 PUT_CODE (incr, NOTE);
2174 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
2175 NOTE_SOURCE_FILE (incr) = 0;
2178 if (regno >= FIRST_PSEUDO_REGISTER)
2180 /* Count an extra reference to the reg. When a reg is
2181 incremented, spilling it is worse, so we want to make
2182 that less likely. */
2183 reg_n_refs[regno] += loop_depth;
2184 /* Count the increment as a setting of the register,
2185 even though it isn't a SET in rtl. */
2186 reg_n_sets[regno]++;
2192 #endif /* AUTO_INC_DEC */
2194 /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
2195 This is done assuming the registers needed from X
2196 are those that have 1-bits in NEEDED.
2198 On the final pass, FINAL is 1. This means try for autoincrement
2199 and count the uses and deaths of each pseudo-reg.
2201 INSN is the containing instruction. If INSN is dead, this function is not
2205 mark_used_regs (needed, live, x, final, insn)
2212 register RTX_CODE code;
2217 code = GET_CODE (x);
2238 /* If we are clobbering a MEM, mark any registers inside the address
2240 if (GET_CODE (XEXP (x, 0)) == MEM)
2241 mark_used_regs (needed, live, XEXP (XEXP (x, 0), 0), final, insn);
2245 /* Invalidate the data for the last MEM stored. We could do this only
2246 if the addresses conflict, but this doesn't seem worthwhile. */
2251 find_auto_inc (needed, x, insn);
2256 /* See a register other than being set
2257 => mark it as needed. */
2261 register int offset = regno / REGSET_ELT_BITS;
2262 register REGSET_ELT_TYPE bit
2263 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2264 REGSET_ELT_TYPE all_needed = needed[offset] & bit;
2265 REGSET_ELT_TYPE some_needed = needed[offset] & bit;
2267 live[offset] |= bit;
2268 /* A hard reg in a wide mode may really be multiple registers.
2269 If so, mark all of them just like the first. */
2270 if (regno < FIRST_PSEUDO_REGISTER)
2274 /* For stack ptr or fixed arg pointer,
2275 nothing below can be necessary, so waste no more time. */
2276 if (regno == STACK_POINTER_REGNUM
2277 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2278 || regno == HARD_FRAME_POINTER_REGNUM
2280 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2281 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2283 || regno == FRAME_POINTER_REGNUM)
2285 /* If this is a register we are going to try to eliminate,
2286 don't mark it live here. If we are successful in
2287 eliminating it, it need not be live unless it is used for
2288 pseudos, in which case it will have been set live when
2289 it was allocated to the pseudos. If the register will not
2290 be eliminated, reload will set it live at that point. */
2292 if (! TEST_HARD_REG_BIT (elim_reg_set, regno))
2293 regs_ever_live[regno] = 1;
2296 /* No death notes for global register variables;
2297 their values are live after this function exits. */
2298 if (global_regs[regno])
2301 reg_next_use[regno] = insn;
2305 n = HARD_REGNO_NREGS (regno, GET_MODE (x));
2308 live[(regno + n) / REGSET_ELT_BITS]
2309 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
2311 |= (needed[(regno + n) / REGSET_ELT_BITS]
2312 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2314 &= (needed[(regno + n) / REGSET_ELT_BITS]
2315 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2320 /* Record where each reg is used, so when the reg
2321 is set we know the next insn that uses it. */
2323 reg_next_use[regno] = insn;
2325 if (regno < FIRST_PSEUDO_REGISTER)
2327 /* If a hard reg is being used,
2328 record that this function does use it. */
2330 i = HARD_REGNO_NREGS (regno, GET_MODE (x));
2334 regs_ever_live[regno + --i] = 1;
2339 /* Keep track of which basic block each reg appears in. */
2341 register int blocknum = BLOCK_NUM (insn);
2343 if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
2344 reg_basic_block[regno] = blocknum;
2345 else if (reg_basic_block[regno] != blocknum)
2346 reg_basic_block[regno] = REG_BLOCK_GLOBAL;
2348 /* Count (weighted) number of uses of each reg. */
2350 reg_n_refs[regno] += loop_depth;
2353 /* Record and count the insns in which a reg dies.
2354 If it is used in this insn and was dead below the insn
2355 then it dies in this insn. If it was set in this insn,
2356 we do not make a REG_DEAD note; likewise if we already
2357 made such a note. */
2360 && ! dead_or_set_p (insn, x)
2362 && (regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
2366 /* If none of the words in X is needed, make a REG_DEAD
2367 note. Otherwise, we must make partial REG_DEAD notes. */
2371 = gen_rtx (EXPR_LIST, REG_DEAD, x, REG_NOTES (insn));
2372 reg_n_deaths[regno]++;
2378 /* Don't make a REG_DEAD note for a part of a register
2379 that is set in the insn. */
2381 for (i = HARD_REGNO_NREGS (regno, GET_MODE (x)) - 1;
2383 if ((needed[(regno + i) / REGSET_ELT_BITS]
2384 & ((REGSET_ELT_TYPE) 1
2385 << ((regno + i) % REGSET_ELT_BITS))) == 0
2386 && ! dead_or_set_regno_p (insn, regno + i))
2388 = gen_rtx (EXPR_LIST, REG_DEAD,
2389 gen_rtx (REG, word_mode, regno + i),
2399 register rtx testreg = SET_DEST (x);
2402 /* If storing into MEM, don't show it as being used. But do
2403 show the address as being used. */
2404 if (GET_CODE (testreg) == MEM)
2408 find_auto_inc (needed, testreg, insn);
2410 mark_used_regs (needed, live, XEXP (testreg, 0), final, insn);
2411 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2415 /* Storing in STRICT_LOW_PART is like storing in a reg
2416 in that this SET might be dead, so ignore it in TESTREG.
2417 but in some other ways it is like using the reg.
2419 Storing in a SUBREG or a bit field is like storing the entire
2420 register in that if the register's value is not used
2421 then this SET is not needed. */
2422 while (GET_CODE (testreg) == STRICT_LOW_PART
2423 || GET_CODE (testreg) == ZERO_EXTRACT
2424 || GET_CODE (testreg) == SIGN_EXTRACT
2425 || GET_CODE (testreg) == SUBREG)
2427 /* Modifying a single register in an alternate mode
2428 does not use any of the old value. But these other
2429 ways of storing in a register do use the old value. */
2430 if (GET_CODE (testreg) == SUBREG
2431 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
2436 testreg = XEXP (testreg, 0);
2439 /* If this is a store into a register,
2440 recursively scan the value being stored. */
2442 if (GET_CODE (testreg) == REG
2443 && (regno = REGNO (testreg), regno != FRAME_POINTER_REGNUM)
2444 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2445 && regno != HARD_FRAME_POINTER_REGNUM
2447 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2448 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2451 /* We used to exclude global_regs here, but that seems wrong.
2452 Storing in them is like storing in mem. */
2454 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2456 mark_used_regs (needed, live, SET_DEST (x), final, insn);
2463 /* If exiting needs the right stack value, consider this insn as
2464 using the stack pointer. In any event, consider it as using
2465 all global registers. */
2467 #ifdef EXIT_IGNORE_STACK
2468 if (! EXIT_IGNORE_STACK
2469 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
2471 live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
2472 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
2474 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2476 live[i / REGSET_ELT_BITS]
2477 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
2481 /* Recursively scan the operands of this expression. */
2484 register char *fmt = GET_RTX_FORMAT (code);
2487 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2491 /* Tail recursive case: save a function call level. */
2497 mark_used_regs (needed, live, XEXP (x, i), final, insn);
2499 else if (fmt[i] == 'E')
2502 for (j = 0; j < XVECLEN (x, i); j++)
2503 mark_used_regs (needed, live, XVECEXP (x, i, j), final, insn);
2512 try_pre_increment_1 (insn)
2515 /* Find the next use of this reg. If in same basic block,
2516 make it do pre-increment or pre-decrement if appropriate. */
2517 rtx x = PATTERN (insn);
2518 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
2519 * INTVAL (XEXP (SET_SRC (x), 1)));
2520 int regno = REGNO (SET_DEST (x));
2521 rtx y = reg_next_use[regno];
2523 && BLOCK_NUM (y) == BLOCK_NUM (insn)
2524 && try_pre_increment (y, SET_DEST (PATTERN (insn)),
2527 /* We have found a suitable auto-increment
2528 and already changed insn Y to do it.
2529 So flush this increment-instruction. */
2530 PUT_CODE (insn, NOTE);
2531 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
2532 NOTE_SOURCE_FILE (insn) = 0;
2533 /* Count a reference to this reg for the increment
2534 insn we are deleting. When a reg is incremented.
2535 spilling it is worse, so we want to make that
2537 if (regno >= FIRST_PSEUDO_REGISTER)
2539 reg_n_refs[regno] += loop_depth;
2540 reg_n_sets[regno]++;
2547 /* Try to change INSN so that it does pre-increment or pre-decrement
2548 addressing on register REG in order to add AMOUNT to REG.
2549 AMOUNT is negative for pre-decrement.
2550 Returns 1 if the change could be made.
2551 This checks all about the validity of the result of modifying INSN. */
2554 try_pre_increment (insn, reg, amount)
2556 HOST_WIDE_INT amount;
2560 /* Nonzero if we can try to make a pre-increment or pre-decrement.
2561 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
2563 /* Nonzero if we can try to make a post-increment or post-decrement.
2564 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
2565 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
2566 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
2569 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
2572 /* From the sign of increment, see which possibilities are conceivable
2573 on this target machine. */
2574 #ifdef HAVE_PRE_INCREMENT
2578 #ifdef HAVE_POST_INCREMENT
2583 #ifdef HAVE_PRE_DECREMENT
2587 #ifdef HAVE_POST_DECREMENT
2592 if (! (pre_ok || post_ok))
2595 /* It is not safe to add a side effect to a jump insn
2596 because if the incremented register is spilled and must be reloaded
2597 there would be no way to store the incremented value back in memory. */
2599 if (GET_CODE (insn) == JUMP_INSN)
2604 use = find_use_as_address (PATTERN (insn), reg, 0);
2605 if (post_ok && (use == 0 || use == (rtx) 1))
2607 use = find_use_as_address (PATTERN (insn), reg, -amount);
2611 if (use == 0 || use == (rtx) 1)
2614 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
2617 XEXP (use, 0) = gen_rtx (amount > 0
2618 ? (do_post ? POST_INC : PRE_INC)
2619 : (do_post ? POST_DEC : PRE_DEC),
2622 /* Record that this insn now has an implicit side effect on X. */
2623 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_INC, reg, REG_NOTES (insn));
2627 #endif /* AUTO_INC_DEC */
2629 /* Find the place in the rtx X where REG is used as a memory address.
2630 Return the MEM rtx that so uses it.
2631 If PLUSCONST is nonzero, search instead for a memory address equivalent to
2632 (plus REG (const_int PLUSCONST)).
2634 If such an address does not appear, return 0.
2635 If REG appears more than once, or is used other than in such an address,
2639 find_use_as_address (x, reg, plusconst)
2642 HOST_WIDE_INT plusconst;
2644 enum rtx_code code = GET_CODE (x);
2645 char *fmt = GET_RTX_FORMAT (code);
2647 register rtx value = 0;
2650 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
2653 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
2654 && XEXP (XEXP (x, 0), 0) == reg
2655 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
2656 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
2659 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
2661 /* If REG occurs inside a MEM used in a bit-field reference,
2662 that is unacceptable. */
2663 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
2664 return (rtx) (HOST_WIDE_INT) 1;
2668 return (rtx) (HOST_WIDE_INT) 1;
2670 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2674 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
2678 return (rtx) (HOST_WIDE_INT) 1;
2683 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
2685 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
2689 return (rtx) (HOST_WIDE_INT) 1;
2697 /* Write information about registers and basic blocks into FILE.
2698 This is part of making a debugging dump. */
2701 dump_flow_info (file)
2705 static char *reg_class_names[] = REG_CLASS_NAMES;
2707 fprintf (file, "%d registers.\n", max_regno);
2709 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
2712 enum reg_class class, altclass;
2713 fprintf (file, "\nRegister %d used %d times across %d insns",
2714 i, reg_n_refs[i], reg_live_length[i]);
2715 if (reg_basic_block[i] >= 0)
2716 fprintf (file, " in block %d", reg_basic_block[i]);
2717 if (reg_n_deaths[i] != 1)
2718 fprintf (file, "; dies in %d places", reg_n_deaths[i]);
2719 if (reg_n_calls_crossed[i] == 1)
2720 fprintf (file, "; crosses 1 call");
2721 else if (reg_n_calls_crossed[i])
2722 fprintf (file, "; crosses %d calls", reg_n_calls_crossed[i]);
2723 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
2724 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
2725 class = reg_preferred_class (i);
2726 altclass = reg_alternate_class (i);
2727 if (class != GENERAL_REGS || altclass != ALL_REGS)
2729 if (altclass == ALL_REGS || class == ALL_REGS)
2730 fprintf (file, "; pref %s", reg_class_names[(int) class]);
2731 else if (altclass == NO_REGS)
2732 fprintf (file, "; %s or none", reg_class_names[(int) class]);
2734 fprintf (file, "; pref %s, else %s",
2735 reg_class_names[(int) class],
2736 reg_class_names[(int) altclass]);
2738 if (REGNO_POINTER_FLAG (i))
2739 fprintf (file, "; pointer");
2740 fprintf (file, ".\n");
2742 fprintf (file, "\n%d basic blocks.\n", n_basic_blocks);
2743 for (i = 0; i < n_basic_blocks; i++)
2745 register rtx head, jump;
2747 fprintf (file, "\nBasic block %d: first insn %d, last %d.\n",
2749 INSN_UID (basic_block_head[i]),
2750 INSN_UID (basic_block_end[i]));
2751 /* The control flow graph's storage is freed
2752 now when flow_analysis returns.
2753 Don't try to print it if it is gone. */
2754 if (basic_block_drops_in)
2756 fprintf (file, "Reached from blocks: ");
2757 head = basic_block_head[i];
2758 if (GET_CODE (head) == CODE_LABEL)
2759 for (jump = LABEL_REFS (head);
2761 jump = LABEL_NEXTREF (jump))
2763 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
2764 fprintf (file, " %d", from_block);
2766 if (basic_block_drops_in[i])
2767 fprintf (file, " previous");
2769 fprintf (file, "\nRegisters live at start:");
2770 for (regno = 0; regno < max_regno; regno++)
2772 register int offset = regno / REGSET_ELT_BITS;
2773 register REGSET_ELT_TYPE bit
2774 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2775 if (basic_block_live_at_start[i][offset] & bit)
2776 fprintf (file, " %d", regno);
2778 fprintf (file, "\n");
2780 fprintf (file, "\n");