1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 88, 92, 93, 94, 95, 1996 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
22 /* This file contains the data flow analysis pass of the compiler.
23 It computes data flow information
24 which tells combine_instructions which insns to consider combining
25 and controls register allocation.
27 Additional data flow information that is too bulky to record
28 is generated during the analysis, and is used at that time to
29 create autoincrement and autodecrement addressing.
31 The first step is dividing the function into basic blocks.
32 find_basic_blocks does this. Then life_analysis determines
33 where each register is live and where it is dead.
35 ** find_basic_blocks **
37 find_basic_blocks divides the current function's rtl
38 into basic blocks. It records the beginnings and ends of the
39 basic blocks in the vectors basic_block_head and basic_block_end,
40 and the number of blocks in n_basic_blocks.
42 find_basic_blocks also finds any unreachable loops
47 life_analysis is called immediately after find_basic_blocks.
48 It uses the basic block information to determine where each
49 hard or pseudo register is live.
51 ** live-register info **
53 The information about where each register is live is in two parts:
54 the REG_NOTES of insns, and the vector basic_block_live_at_start.
56 basic_block_live_at_start has an element for each basic block,
57 and the element is a bit-vector with a bit for each hard or pseudo
58 register. The bit is 1 if the register is live at the beginning
61 Two types of elements can be added to an insn's REG_NOTES.
62 A REG_DEAD note is added to an insn's REG_NOTES for any register
63 that meets both of two conditions: The value in the register is not
64 needed in subsequent insns and the insn does not replace the value in
65 the register (in the case of multi-word hard registers, the value in
66 each register must be replaced by the insn to avoid a REG_DEAD note).
68 In the vast majority of cases, an object in a REG_DEAD note will be
69 used somewhere in the insn. The (rare) exception to this is if an
70 insn uses a multi-word hard register and only some of the registers are
71 needed in subsequent insns. In that case, REG_DEAD notes will be
72 provided for those hard registers that are not subsequently needed.
73 Partial REG_DEAD notes of this type do not occur when an insn sets
74 only some of the hard registers used in such a multi-word operand;
75 omitting REG_DEAD notes for objects stored in an insn is optional and
76 the desire to do so does not justify the complexity of the partial
79 REG_UNUSED notes are added for each register that is set by the insn
80 but is unused subsequently (if every register set by the insn is unused
81 and the insn does not reference memory or have some other side-effect,
82 the insn is deleted instead). If only part of a multi-word hard
83 register is used in a subsequent insn, REG_UNUSED notes are made for
84 the parts that will not be used.
86 To determine which registers are live after any insn, one can
87 start from the beginning of the basic block and scan insns, noting
88 which registers are set by each insn and which die there.
90 ** Other actions of life_analysis **
92 life_analysis sets up the LOG_LINKS fields of insns because the
93 information needed to do so is readily available.
95 life_analysis deletes insns whose only effect is to store a value
98 life_analysis notices cases where a reference to a register as
99 a memory address can be combined with a preceding or following
100 incrementation or decrementation of the register. The separate
101 instruction to increment or decrement is deleted and the address
102 is changed to a POST_INC or similar rtx.
104 Each time an incrementing or decrementing address is created,
105 a REG_INC element is added to the insn's REG_NOTES list.
107 life_analysis fills in certain vectors containing information about
108 register usage: reg_n_refs, reg_n_deaths, reg_n_sets, reg_live_length,
109 reg_n_calls_crosses and reg_basic_block. */
114 #include "basic-block.h"
115 #include "insn-config.h"
117 #include "hard-reg-set.h"
122 #define obstack_chunk_alloc xmalloc
123 #define obstack_chunk_free free
125 /* List of labels that must never be deleted. */
126 extern rtx forced_labels;
128 /* Get the basic block number of an insn.
129 This info should not be expected to remain available
130 after the end of life_analysis. */
132 /* This is the limit of the allocated space in the following two arrays. */
134 static int max_uid_for_flow;
136 #define BLOCK_NUM(INSN) uid_block_number[INSN_UID (INSN)]
138 /* This is where the BLOCK_NUM values are really stored.
139 This is set up by find_basic_blocks and used there and in life_analysis,
142 static int *uid_block_number;
144 /* INSN_VOLATILE (insn) is 1 if the insn refers to anything volatile. */
146 #define INSN_VOLATILE(INSN) uid_volatile[INSN_UID (INSN)]
147 static char *uid_volatile;
149 /* Number of basic blocks in the current function. */
153 /* Maximum register number used in this function, plus one. */
157 /* Maximum number of SCRATCH rtx's used in any basic block of this function. */
161 /* Number of SCRATCH rtx's in the current block. */
163 static int num_scratch;
165 /* Indexed by n, gives number of basic block that (REG n) is used in.
166 If the value is REG_BLOCK_GLOBAL (-2),
167 it means (REG n) is used in more than one basic block.
168 REG_BLOCK_UNKNOWN (-1) means it hasn't been seen yet so we don't know.
169 This information remains valid for the rest of the compilation
170 of the current function; it is used to control register allocation. */
172 int *reg_basic_block;
174 /* Indexed by n, gives number of times (REG n) is used or set, each
175 weighted by its loop-depth.
176 This information remains valid for the rest of the compilation
177 of the current function; it is used to control register allocation. */
181 /* Indexed by N; says whether a pseudo register N was ever used
182 within a SUBREG that changes the size of the reg. Some machines prohibit
183 such objects to be in certain (usually floating-point) registers. */
185 char *reg_changes_size;
187 /* Indexed by N, gives number of places register N dies.
188 This information remains valid for the rest of the compilation
189 of the current function; it is used to control register allocation. */
193 /* Indexed by N, gives 1 if that reg is live across any CALL_INSNs.
194 This information remains valid for the rest of the compilation
195 of the current function; it is used to control register allocation. */
197 int *reg_n_calls_crossed;
199 /* Total number of instructions at which (REG n) is live.
200 The larger this is, the less priority (REG n) gets for
201 allocation in a real register.
202 This information remains valid for the rest of the compilation
203 of the current function; it is used to control register allocation.
205 local-alloc.c may alter this number to change the priority.
207 Negative values are special.
208 -1 is used to mark a pseudo reg which has a constant or memory equivalent
209 and is used infrequently enough that it should not get a hard register.
210 -2 is used to mark a pseudo reg for a parameter, when a frame pointer
211 is not required. global.c makes an allocno for this but does
212 not try to assign a hard register to it. */
214 int *reg_live_length;
216 /* Element N is the next insn that uses (hard or pseudo) register number N
217 within the current basic block; or zero, if there is no such insn.
218 This is valid only during the final backward scan in propagate_block. */
220 static rtx *reg_next_use;
222 /* Size of a regset for the current function,
223 in (1) bytes and (2) elements. */
228 /* Element N is first insn in basic block N.
229 This info lasts until we finish compiling the function. */
231 rtx *basic_block_head;
233 /* Element N is last insn in basic block N.
234 This info lasts until we finish compiling the function. */
236 rtx *basic_block_end;
238 /* Element N is a regset describing the registers live
239 at the start of basic block N.
240 This info lasts until we finish compiling the function. */
242 regset *basic_block_live_at_start;
244 /* Regset of regs live when calls to `setjmp'-like functions happen. */
246 regset regs_live_at_setjmp;
248 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
249 that have to go in the same hard reg.
250 The first two regs in the list are a pair, and the next two
251 are another pair, etc. */
254 /* Element N is nonzero if control can drop into basic block N
255 from the preceding basic block. Freed after life_analysis. */
257 static char *basic_block_drops_in;
259 /* Element N is depth within loops of the last insn in basic block number N.
260 Freed after life_analysis. */
262 static short *basic_block_loop_depth;
264 /* Element N nonzero if basic block N can actually be reached.
265 Vector exists only during find_basic_blocks. */
267 static char *block_live_static;
269 /* Depth within loops of basic block being scanned for lifetime analysis,
270 plus one. This is the weight attached to references to registers. */
272 static int loop_depth;
274 /* During propagate_block, this is non-zero if the value of CC0 is live. */
278 /* During propagate_block, this contains the last MEM stored into. It
279 is used to eliminate consecutive stores to the same location. */
281 static rtx last_mem_set;
283 /* Set of registers that may be eliminable. These are handled specially
284 in updating regs_ever_live. */
286 static HARD_REG_SET elim_reg_set;
288 /* Forward declarations */
289 static void find_basic_blocks PROTO((rtx, rtx));
290 static int jmp_uses_reg_or_mem PROTO((rtx));
291 static void mark_label_ref PROTO((rtx, rtx, int));
292 static void life_analysis PROTO((rtx, int));
293 void allocate_for_life_analysis PROTO((void));
294 static void init_regset_vector PROTO((regset *, regset, int, int));
295 static void propagate_block PROTO((regset, rtx, rtx, int,
297 static rtx flow_delete_insn PROTO((rtx));
298 static int insn_dead_p PROTO((rtx, regset, int));
299 static int libcall_dead_p PROTO((rtx, regset, rtx, rtx));
300 static void mark_set_regs PROTO((regset, regset, rtx,
302 static void mark_set_1 PROTO((regset, regset, rtx,
304 static void find_auto_inc PROTO((regset, rtx, rtx));
305 static void mark_used_regs PROTO((regset, regset, rtx, int, rtx));
306 static int try_pre_increment_1 PROTO((rtx));
307 static int try_pre_increment PROTO((rtx, rtx, HOST_WIDE_INT));
308 static rtx find_use_as_address PROTO((rtx, rtx, HOST_WIDE_INT));
309 void dump_flow_info PROTO((FILE *));
311 /* Find basic blocks of the current function and perform data flow analysis.
312 F is the first insn of the function and NREGS the number of register numbers
316 flow_analysis (f, nregs, file)
323 rtx nonlocal_label_list = nonlocal_label_rtx_list ();
325 #ifdef ELIMINABLE_REGS
326 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
329 /* Record which registers will be eliminated. We use this in
332 CLEAR_HARD_REG_SET (elim_reg_set);
334 #ifdef ELIMINABLE_REGS
335 for (i = 0; i < sizeof eliminables / sizeof eliminables[0]; i++)
336 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
338 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
341 /* Count the basic blocks. Also find maximum insn uid value used. */
344 register RTX_CODE prev_code = JUMP_INSN;
345 register RTX_CODE code;
347 max_uid_for_flow = 0;
349 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
351 code = GET_CODE (insn);
352 if (INSN_UID (insn) > max_uid_for_flow)
353 max_uid_for_flow = INSN_UID (insn);
354 if (code == CODE_LABEL
355 || (GET_RTX_CLASS (code) == 'i'
356 && (prev_code == JUMP_INSN
357 || (prev_code == CALL_INSN
358 && nonlocal_label_list != 0)
359 || prev_code == BARRIER)))
367 /* Leave space for insns we make in some cases for auto-inc. These cases
368 are rare, so we don't need too much space. */
369 max_uid_for_flow += max_uid_for_flow / 10;
372 /* Allocate some tables that last till end of compiling this function
373 and some needed only in find_basic_blocks and life_analysis. */
376 basic_block_head = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
377 basic_block_end = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
378 basic_block_drops_in = (char *) alloca (n_basic_blocks);
379 basic_block_loop_depth = (short *) alloca (n_basic_blocks * sizeof (short));
381 = (int *) alloca ((max_uid_for_flow + 1) * sizeof (int));
382 uid_volatile = (char *) alloca (max_uid_for_flow + 1);
383 bzero (uid_volatile, max_uid_for_flow + 1);
385 find_basic_blocks (f, nonlocal_label_list);
386 life_analysis (f, nregs);
388 dump_flow_info (file);
390 basic_block_drops_in = 0;
391 uid_block_number = 0;
392 basic_block_loop_depth = 0;
395 /* Find all basic blocks of the function whose first insn is F.
396 Store the correct data in the tables that describe the basic blocks,
397 set up the chains of references for each CODE_LABEL, and
398 delete any entire basic blocks that cannot be reached.
400 NONLOCAL_LABEL_LIST is the same local variable from flow_analysis. */
403 find_basic_blocks (f, nonlocal_label_list)
404 rtx f, nonlocal_label_list;
408 register char *block_live = (char *) alloca (n_basic_blocks);
409 register char *block_marked = (char *) alloca (n_basic_blocks);
410 /* List of label_refs to all labels whose addresses are taken
412 rtx label_value_list;
414 enum rtx_code prev_code, code;
420 label_value_list = 0;
421 block_live_static = block_live;
422 bzero (block_live, n_basic_blocks);
423 bzero (block_marked, n_basic_blocks);
425 /* Initialize with just block 0 reachable and no blocks marked. */
426 if (n_basic_blocks > 0)
429 /* Initialize the ref chain of each label to 0. Record where all the
430 blocks start and end and their depth in loops. For each insn, record
431 the block it is in. Also mark as reachable any blocks headed by labels
432 that must not be deleted. */
434 for (insn = f, i = -1, prev_code = JUMP_INSN, depth = 1;
435 insn; insn = NEXT_INSN (insn))
437 code = GET_CODE (insn);
440 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
442 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
446 /* A basic block starts at label, or after something that can jump. */
447 else if (code == CODE_LABEL
448 || (GET_RTX_CLASS (code) == 'i'
449 && (prev_code == JUMP_INSN
450 || (prev_code == CALL_INSN
451 && nonlocal_label_list != 0)
452 || prev_code == BARRIER)))
454 basic_block_head[++i] = insn;
455 basic_block_end[i] = insn;
456 basic_block_loop_depth[i] = depth;
458 if (code == CODE_LABEL)
460 LABEL_REFS (insn) = insn;
461 /* Any label that cannot be deleted
462 is considered to start a reachable block. */
463 if (LABEL_PRESERVE_P (insn))
468 else if (GET_RTX_CLASS (code) == 'i')
470 basic_block_end[i] = insn;
471 basic_block_loop_depth[i] = depth;
474 if (GET_RTX_CLASS (code) == 'i')
476 /* Make a list of all labels referred to other than by jumps. */
477 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
478 if (REG_NOTE_KIND (note) == REG_LABEL)
479 label_value_list = gen_rtx (EXPR_LIST, VOIDmode, XEXP (note, 0),
483 BLOCK_NUM (insn) = i;
489 /* During the second pass, `n_basic_blocks' is only an upper bound.
490 Only perform the sanity check for the first pass, and on the second
491 pass ensure `n_basic_blocks' is set to the correct value. */
492 if (pass == 1 && i + 1 != n_basic_blocks)
494 n_basic_blocks = i + 1;
496 /* Don't delete the labels (in this function)
497 that are referenced by non-jump instructions. */
499 for (x = label_value_list; x; x = XEXP (x, 1))
500 if (! LABEL_REF_NONLOCAL_P (x))
501 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
503 for (x = forced_labels; x; x = XEXP (x, 1))
504 if (! LABEL_REF_NONLOCAL_P (x))
505 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
507 /* Record which basic blocks control can drop in to. */
509 for (i = 0; i < n_basic_blocks; i++)
511 for (insn = PREV_INSN (basic_block_head[i]);
512 insn && GET_CODE (insn) == NOTE; insn = PREV_INSN (insn))
515 basic_block_drops_in[i] = insn && GET_CODE (insn) != BARRIER;
518 /* Now find which basic blocks can actually be reached
519 and put all jump insns' LABEL_REFS onto the ref-chains
520 of their target labels. */
522 if (n_basic_blocks > 0)
524 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 && jmp_uses_reg_or_mem (SET_SRC (XVECEXP (pat, 0, i))))
559 else if (GET_CODE (pat) == SET
560 && SET_DEST (pat) == pc_rtx
561 && jmp_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 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
586 /* ??? This could be made smarter:
587 in some cases it's possible to tell that certain
588 calls will not do a nonlocal goto.
590 For example, if the nested functions that do the
591 nonlocal gotos do not have their addresses taken, then
592 only calls to those functions or to other nested
593 functions that use them could possibly do nonlocal
597 /* Pass over all blocks, marking each block that is reachable
598 and has not yet been marked.
599 Keep doing this until, in one pass, no blocks have been marked.
600 Then blocks_live and blocks_marked are identical and correct.
601 In addition, all jumps actually reachable have been marked. */
603 while (something_marked)
605 something_marked = 0;
606 for (i = 0; i < n_basic_blocks; i++)
607 if (block_live[i] && !block_marked[i])
610 something_marked = 1;
611 if (i + 1 < n_basic_blocks && basic_block_drops_in[i + 1])
612 block_live[i + 1] = 1;
613 insn = basic_block_end[i];
614 if (GET_CODE (insn) == JUMP_INSN)
615 mark_label_ref (PATTERN (insn), insn, 0);
619 /* ??? See if we have a "live" basic block that is not reachable.
620 This can happen if it is headed by a label that is preserved or
621 in one of the label lists, but no call or computed jump is in
622 the loop. It's not clear if we can delete the block or not,
623 but don't for now. However, we will mess up register status if
624 it remains unreachable, so add a fake reachability from the
627 for (i = 1; i < n_basic_blocks; i++)
628 if (block_live[i] && ! basic_block_drops_in[i]
629 && GET_CODE (basic_block_head[i]) == CODE_LABEL
630 && LABEL_REFS (basic_block_head[i]) == basic_block_head[i])
631 basic_block_drops_in[i] = 1;
633 /* Now delete the code for any basic blocks that can't be reached.
634 They can occur because jump_optimize does not recognize
635 unreachable loops as unreachable. */
638 for (i = 0; i < n_basic_blocks; i++)
643 /* Delete the insns in a (non-live) block. We physically delete
644 every non-note insn except the start and end (so
645 basic_block_head/end needn't be updated), we turn the latter
646 into NOTE_INSN_DELETED notes.
647 We use to "delete" the insns by turning them into notes, but
648 we may be deleting lots of insns that subsequent passes would
649 otherwise have to process. Secondly, lots of deleted blocks in
650 a row can really slow down propagate_block since it will
651 otherwise process insn-turned-notes multiple times when it
652 looks for loop begin/end notes. */
653 if (basic_block_head[i] != basic_block_end[i])
655 /* It would be quicker to delete all of these with a single
656 unchaining, rather than one at a time, but we need to keep
658 insn = NEXT_INSN (basic_block_head[i]);
659 while (insn != basic_block_end[i])
661 if (GET_CODE (insn) == BARRIER)
663 else if (GET_CODE (insn) != NOTE)
664 insn = flow_delete_insn (insn);
666 insn = NEXT_INSN (insn);
669 insn = basic_block_head[i];
670 if (GET_CODE (insn) != NOTE)
672 /* Turn the head into a deleted insn note. */
673 if (GET_CODE (insn) == BARRIER)
675 PUT_CODE (insn, NOTE);
676 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
677 NOTE_SOURCE_FILE (insn) = 0;
679 insn = basic_block_end[i];
680 if (GET_CODE (insn) != NOTE)
682 /* Turn the tail into a deleted insn note. */
683 if (GET_CODE (insn) == BARRIER)
685 PUT_CODE (insn, NOTE);
686 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
687 NOTE_SOURCE_FILE (insn) = 0;
689 /* BARRIERs are between basic blocks, not part of one.
690 Delete a BARRIER if the preceding jump is deleted.
691 We cannot alter a BARRIER into a NOTE
692 because it is too short; but we can really delete
693 it because it is not part of a basic block. */
694 if (NEXT_INSN (insn) != 0
695 && GET_CODE (NEXT_INSN (insn)) == BARRIER)
696 delete_insn (NEXT_INSN (insn));
698 /* Each time we delete some basic blocks,
699 see if there is a jump around them that is
700 being turned into a no-op. If so, delete it. */
702 if (block_live[i - 1])
705 for (j = i + 1; j < n_basic_blocks; j++)
709 insn = basic_block_end[i - 1];
710 if (GET_CODE (insn) == JUMP_INSN
711 /* An unconditional jump is the only possibility
712 we must check for, since a conditional one
713 would make these blocks live. */
714 && simplejump_p (insn)
715 && (label = XEXP (SET_SRC (PATTERN (insn)), 0), 1)
716 && INSN_UID (label) != 0
717 && BLOCK_NUM (label) == j)
719 PUT_CODE (insn, NOTE);
720 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
721 NOTE_SOURCE_FILE (insn) = 0;
722 if (GET_CODE (NEXT_INSN (insn)) != BARRIER)
724 delete_insn (NEXT_INSN (insn));
731 /* There are pathological cases where one function calling hundreds of
732 nested inline functions can generate lots and lots of unreachable
733 blocks that jump can't delete. Since we don't use sparse matrices
734 a lot of memory will be needed to compile such functions.
735 Implementing sparse matrices is a fair bit of work and it is not
736 clear that they win more than they lose (we don't want to
737 unnecessarily slow down compilation of normal code). By making
738 another pass for the pathological case, we can greatly speed up
739 their compilation without hurting normal code. This works because
740 all the insns in the unreachable blocks have either been deleted or
742 Note that we're talking about reducing memory usage by 10's of
743 megabytes and reducing compilation time by several minutes. */
744 /* ??? The choice of when to make another pass is a bit arbitrary,
745 and was derived from empirical data. */
750 n_basic_blocks -= deleted;
751 /* `n_basic_blocks' may not be correct at this point: two previously
752 separate blocks may now be merged. That's ok though as we
753 recalculate it during the second pass. It certainly can't be
754 any larger than the current value. */
760 /* Subroutines of find_basic_blocks. */
762 /* Return 1 if X, the SRC_SRC of SET of (pc) contain a REG or MEM that is
763 not in the constant pool and not in the condition of an IF_THEN_ELSE. */
766 jmp_uses_reg_or_mem (x)
769 enum rtx_code code = GET_CODE (x);
784 return ! (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
785 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)));
788 return (jmp_uses_reg_or_mem (XEXP (x, 1))
789 || jmp_uses_reg_or_mem (XEXP (x, 2)));
791 case PLUS: case MINUS: case MULT:
792 return (jmp_uses_reg_or_mem (XEXP (x, 0))
793 || jmp_uses_reg_or_mem (XEXP (x, 1)));
796 fmt = GET_RTX_FORMAT (code);
797 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
800 && jmp_uses_reg_or_mem (XEXP (x, i)))
804 for (j = 0; j < XVECLEN (x, i); j++)
805 if (jmp_uses_reg_or_mem (XVECEXP (x, i, j)))
812 /* Check expression X for label references;
813 if one is found, add INSN to the label's chain of references.
815 CHECKDUP means check for and avoid creating duplicate references
816 from the same insn. Such duplicates do no serious harm but
817 can slow life analysis. CHECKDUP is set only when duplicates
821 mark_label_ref (x, insn, checkdup)
825 register RTX_CODE code;
829 /* We can be called with NULL when scanning label_value_list. */
834 if (code == LABEL_REF)
836 register rtx label = XEXP (x, 0);
838 if (GET_CODE (label) != CODE_LABEL)
840 /* If the label was never emitted, this insn is junk,
841 but avoid a crash trying to refer to BLOCK_NUM (label).
842 This can happen as a result of a syntax error
843 and a diagnostic has already been printed. */
844 if (INSN_UID (label) == 0)
846 CONTAINING_INSN (x) = insn;
847 /* if CHECKDUP is set, check for duplicate ref from same insn
850 for (y = LABEL_REFS (label); y != label; y = LABEL_NEXTREF (y))
851 if (CONTAINING_INSN (y) == insn)
853 LABEL_NEXTREF (x) = LABEL_REFS (label);
854 LABEL_REFS (label) = x;
855 block_live_static[BLOCK_NUM (label)] = 1;
859 fmt = GET_RTX_FORMAT (code);
860 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
863 mark_label_ref (XEXP (x, i), insn, 0);
867 for (j = 0; j < XVECLEN (x, i); j++)
868 mark_label_ref (XVECEXP (x, i, j), insn, 1);
873 /* Delete INSN by patching it out.
874 Return the next insn. */
877 flow_delete_insn (insn)
880 /* ??? For the moment we assume we don't have to watch for NULLs here
881 since the start/end of basic blocks aren't deleted like this. */
882 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
883 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
884 return NEXT_INSN (insn);
887 /* Determine which registers are live at the start of each
888 basic block of the function whose first insn is F.
889 NREGS is the number of registers used in F.
890 We allocate the vector basic_block_live_at_start
891 and the regsets that it points to, and fill them with the data.
892 regset_size and regset_bytes are also set here. */
895 life_analysis (f, nregs)
902 /* For each basic block, a bitmask of regs
903 live on exit from the block. */
904 regset *basic_block_live_at_end;
905 /* For each basic block, a bitmask of regs
906 live on entry to a successor-block of this block.
907 If this does not match basic_block_live_at_end,
908 that must be updated, and the block must be rescanned. */
909 regset *basic_block_new_live_at_end;
910 /* For each basic block, a bitmask of regs
911 whose liveness at the end of the basic block
912 can make a difference in which regs are live on entry to the block.
913 These are the regs that are set within the basic block,
914 possibly excluding those that are used after they are set. */
915 regset *basic_block_significant;
919 struct obstack flow_obstack;
921 gcc_obstack_init (&flow_obstack);
925 bzero (regs_ever_live, sizeof regs_ever_live);
927 /* Allocate and zero out many data structures
928 that will record the data from lifetime analysis. */
930 allocate_for_life_analysis ();
932 reg_next_use = (rtx *) alloca (nregs * sizeof (rtx));
933 bzero ((char *) reg_next_use, nregs * sizeof (rtx));
935 /* Set up several regset-vectors used internally within this function.
936 Their meanings are documented above, with their declarations. */
938 basic_block_live_at_end
939 = (regset *) alloca (n_basic_blocks * sizeof (regset));
941 /* Don't use alloca since that leads to a crash rather than an error message
942 if there isn't enough space.
943 Don't use oballoc since we may need to allocate other things during
944 this function on the temporary obstack. */
945 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
946 bzero ((char *) tem, n_basic_blocks * regset_bytes);
947 init_regset_vector (basic_block_live_at_end, tem,
948 n_basic_blocks, regset_bytes);
950 basic_block_new_live_at_end
951 = (regset *) alloca (n_basic_blocks * sizeof (regset));
952 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
953 bzero ((char *) tem, n_basic_blocks * regset_bytes);
954 init_regset_vector (basic_block_new_live_at_end, tem,
955 n_basic_blocks, regset_bytes);
957 basic_block_significant
958 = (regset *) alloca (n_basic_blocks * sizeof (regset));
959 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
960 bzero ((char *) tem, n_basic_blocks * regset_bytes);
961 init_regset_vector (basic_block_significant, tem,
962 n_basic_blocks, regset_bytes);
964 /* Record which insns refer to any volatile memory
965 or for any reason can't be deleted just because they are dead stores.
966 Also, delete any insns that copy a register to itself. */
968 for (insn = f; insn; insn = NEXT_INSN (insn))
970 enum rtx_code code1 = GET_CODE (insn);
971 if (code1 == CALL_INSN)
972 INSN_VOLATILE (insn) = 1;
973 else if (code1 == INSN || code1 == JUMP_INSN)
975 /* Delete (in effect) any obvious no-op moves. */
976 if (GET_CODE (PATTERN (insn)) == SET
977 && GET_CODE (SET_DEST (PATTERN (insn))) == REG
978 && GET_CODE (SET_SRC (PATTERN (insn))) == REG
979 && REGNO (SET_DEST (PATTERN (insn))) ==
980 REGNO (SET_SRC (PATTERN (insn)))
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;
988 else if (GET_CODE (PATTERN (insn)) == PARALLEL)
990 /* If nothing but SETs of registers to themselves,
991 this insn can also be deleted. */
992 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
994 rtx tem = XVECEXP (PATTERN (insn), 0, i);
996 if (GET_CODE (tem) == USE
997 || GET_CODE (tem) == CLOBBER)
1000 if (GET_CODE (tem) != SET
1001 || GET_CODE (SET_DEST (tem)) != REG
1002 || GET_CODE (SET_SRC (tem)) != REG
1003 || REGNO (SET_DEST (tem)) != REGNO (SET_SRC (tem)))
1007 if (i == XVECLEN (PATTERN (insn), 0)
1008 /* Insns carrying these notes are useful later on. */
1009 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
1011 PUT_CODE (insn, NOTE);
1012 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
1013 NOTE_SOURCE_FILE (insn) = 0;
1016 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
1018 else if (GET_CODE (PATTERN (insn)) != USE)
1019 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
1020 /* A SET that makes space on the stack cannot be dead.
1021 (Such SETs occur only for allocating variable-size data,
1022 so they will always have a PLUS or MINUS according to the
1023 direction of stack growth.)
1024 Even if this function never uses this stack pointer value,
1025 signal handlers do! */
1026 else if (code1 == INSN && GET_CODE (PATTERN (insn)) == SET
1027 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1028 #ifdef STACK_GROWS_DOWNWARD
1029 && GET_CODE (SET_SRC (PATTERN (insn))) == MINUS
1031 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1033 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx)
1034 INSN_VOLATILE (insn) = 1;
1038 if (n_basic_blocks > 0)
1039 #ifdef EXIT_IGNORE_STACK
1040 if (! EXIT_IGNORE_STACK
1041 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
1044 /* If exiting needs the right stack value,
1045 consider the stack pointer live at the end of the function. */
1046 basic_block_live_at_end[n_basic_blocks - 1]
1047 [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
1048 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
1049 basic_block_new_live_at_end[n_basic_blocks - 1]
1050 [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
1051 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
1054 /* Mark the frame pointer is needed at the end of the function. If
1055 we end up eliminating it, it will be removed from the live list
1056 of each basic block by reload. */
1058 if (n_basic_blocks > 0)
1060 basic_block_live_at_end[n_basic_blocks - 1]
1061 [FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
1062 |= (REGSET_ELT_TYPE) 1 << (FRAME_POINTER_REGNUM % REGSET_ELT_BITS);
1063 basic_block_new_live_at_end[n_basic_blocks - 1]
1064 [FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
1065 |= (REGSET_ELT_TYPE) 1 << (FRAME_POINTER_REGNUM % REGSET_ELT_BITS);
1066 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1067 /* If they are different, also mark the hard frame pointer as live */
1068 basic_block_live_at_end[n_basic_blocks - 1]
1069 [HARD_FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
1070 |= (REGSET_ELT_TYPE) 1 << (HARD_FRAME_POINTER_REGNUM
1072 basic_block_new_live_at_end[n_basic_blocks - 1]
1073 [HARD_FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
1074 |= (REGSET_ELT_TYPE) 1 << (HARD_FRAME_POINTER_REGNUM
1079 /* Mark all global registers as being live at the end of the function
1080 since they may be referenced by our caller. */
1082 if (n_basic_blocks > 0)
1083 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1086 basic_block_live_at_end[n_basic_blocks - 1]
1087 [i / REGSET_ELT_BITS]
1088 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
1089 basic_block_new_live_at_end[n_basic_blocks - 1]
1090 [i / REGSET_ELT_BITS]
1091 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
1094 /* Propagate life info through the basic blocks
1095 around the graph of basic blocks.
1097 This is a relaxation process: each time a new register
1098 is live at the end of the basic block, we must scan the block
1099 to determine which registers are, as a consequence, live at the beginning
1100 of that block. These registers must then be marked live at the ends
1101 of all the blocks that can transfer control to that block.
1102 The process continues until it reaches a fixed point. */
1109 for (i = n_basic_blocks - 1; i >= 0; i--)
1111 int consider = first_pass;
1112 int must_rescan = first_pass;
1117 /* Set CONSIDER if this block needs thinking about at all
1118 (that is, if the regs live now at the end of it
1119 are not the same as were live at the end of it when
1120 we last thought about it).
1121 Set must_rescan if it needs to be thought about
1122 instruction by instruction (that is, if any additional
1123 reg that is live at the end now but was not live there before
1124 is one of the significant regs of this basic block). */
1126 for (j = 0; j < regset_size; j++)
1128 register REGSET_ELT_TYPE x
1129 = (basic_block_new_live_at_end[i][j]
1130 & ~basic_block_live_at_end[i][j]);
1133 if (x & basic_block_significant[i][j])
1145 /* The live_at_start of this block may be changing,
1146 so another pass will be required after this one. */
1151 /* No complete rescan needed;
1152 just record those variables newly known live at end
1153 as live at start as well. */
1154 for (j = 0; j < regset_size; j++)
1156 register REGSET_ELT_TYPE x
1157 = (basic_block_new_live_at_end[i][j]
1158 & ~basic_block_live_at_end[i][j]);
1159 basic_block_live_at_start[i][j] |= x;
1160 basic_block_live_at_end[i][j] |= x;
1165 /* Update the basic_block_live_at_start
1166 by propagation backwards through the block. */
1167 bcopy ((char *) basic_block_new_live_at_end[i],
1168 (char *) basic_block_live_at_end[i], regset_bytes);
1169 bcopy ((char *) basic_block_live_at_end[i],
1170 (char *) basic_block_live_at_start[i], regset_bytes);
1171 propagate_block (basic_block_live_at_start[i],
1172 basic_block_head[i], basic_block_end[i], 0,
1173 first_pass ? basic_block_significant[i]
1179 register rtx jump, head;
1181 /* Update the basic_block_new_live_at_end's of the block
1182 that falls through into this one (if any). */
1183 head = basic_block_head[i];
1184 if (basic_block_drops_in[i])
1187 for (j = 0; j < regset_size; j++)
1188 basic_block_new_live_at_end[i-1][j]
1189 |= basic_block_live_at_start[i][j];
1192 /* Update the basic_block_new_live_at_end's of
1193 all the blocks that jump to this one. */
1194 if (GET_CODE (head) == CODE_LABEL)
1195 for (jump = LABEL_REFS (head);
1197 jump = LABEL_NEXTREF (jump))
1199 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
1201 for (j = 0; j < regset_size; j++)
1202 basic_block_new_live_at_end[from_block][j]
1203 |= basic_block_live_at_start[i][j];
1213 /* The only pseudos that are live at the beginning of the function are
1214 those that were not set anywhere in the function. local-alloc doesn't
1215 know how to handle these correctly, so mark them as not local to any
1218 if (n_basic_blocks > 0)
1219 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
1220 if (basic_block_live_at_start[0][i / REGSET_ELT_BITS]
1221 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
1222 reg_basic_block[i] = REG_BLOCK_GLOBAL;
1224 /* Now the life information is accurate.
1225 Make one more pass over each basic block
1226 to delete dead stores, create autoincrement addressing
1227 and record how many times each register is used, is set, or dies.
1229 To save time, we operate directly in basic_block_live_at_end[i],
1230 thus destroying it (in fact, converting it into a copy of
1231 basic_block_live_at_start[i]). This is ok now because
1232 basic_block_live_at_end[i] is no longer used past this point. */
1236 for (i = 0; i < n_basic_blocks; i++)
1238 propagate_block (basic_block_live_at_end[i],
1239 basic_block_head[i], basic_block_end[i], 1,
1247 /* Something live during a setjmp should not be put in a register
1248 on certain machines which restore regs from stack frames
1249 rather than from the jmpbuf.
1250 But we don't need to do this for the user's variables, since
1251 ANSI says only volatile variables need this. */
1252 #ifdef LONGJMP_RESTORE_FROM_STACK
1253 for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1254 if (regs_live_at_setjmp[i / REGSET_ELT_BITS]
1255 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS))
1256 && regno_reg_rtx[i] != 0 && ! REG_USERVAR_P (regno_reg_rtx[i]))
1258 reg_live_length[i] = -1;
1259 reg_basic_block[i] = -1;
1264 /* We have a problem with any pseudoreg that
1265 lives across the setjmp. ANSI says that if a
1266 user variable does not change in value
1267 between the setjmp and the longjmp, then the longjmp preserves it.
1268 This includes longjmp from a place where the pseudo appears dead.
1269 (In principle, the value still exists if it is in scope.)
1270 If the pseudo goes in a hard reg, some other value may occupy
1271 that hard reg where this pseudo is dead, thus clobbering the pseudo.
1272 Conclusion: such a pseudo must not go in a hard reg. */
1273 for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1274 if ((regs_live_at_setjmp[i / REGSET_ELT_BITS]
1275 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
1276 && regno_reg_rtx[i] != 0)
1278 reg_live_length[i] = -1;
1279 reg_basic_block[i] = -1;
1282 obstack_free (&flow_obstack, NULL_PTR);
1285 /* Subroutines of life analysis. */
1287 /* Allocate the permanent data structures that represent the results
1288 of life analysis. Not static since used also for stupid life analysis. */
1291 allocate_for_life_analysis ()
1294 register regset tem;
1296 regset_size = ((max_regno + REGSET_ELT_BITS - 1) / REGSET_ELT_BITS);
1297 regset_bytes = regset_size * sizeof (*(regset)0);
1299 reg_n_refs = (int *) oballoc (max_regno * sizeof (int));
1300 bzero ((char *) reg_n_refs, max_regno * sizeof (int));
1302 reg_n_sets = (short *) oballoc (max_regno * sizeof (short));
1303 bzero ((char *) reg_n_sets, max_regno * sizeof (short));
1305 reg_n_deaths = (short *) oballoc (max_regno * sizeof (short));
1306 bzero ((char *) reg_n_deaths, max_regno * sizeof (short));
1308 reg_changes_size = (char *) oballoc (max_regno * sizeof (char));
1309 bzero (reg_changes_size, max_regno * sizeof (char));;
1311 reg_live_length = (int *) oballoc (max_regno * sizeof (int));
1312 bzero ((char *) reg_live_length, max_regno * sizeof (int));
1314 reg_n_calls_crossed = (int *) oballoc (max_regno * sizeof (int));
1315 bzero ((char *) reg_n_calls_crossed, max_regno * sizeof (int));
1317 reg_basic_block = (int *) oballoc (max_regno * sizeof (int));
1318 for (i = 0; i < max_regno; i++)
1319 reg_basic_block[i] = REG_BLOCK_UNKNOWN;
1321 basic_block_live_at_start
1322 = (regset *) oballoc (n_basic_blocks * sizeof (regset));
1323 tem = (regset) oballoc (n_basic_blocks * regset_bytes);
1324 bzero ((char *) tem, n_basic_blocks * regset_bytes);
1325 init_regset_vector (basic_block_live_at_start, tem,
1326 n_basic_blocks, regset_bytes);
1328 regs_live_at_setjmp = (regset) oballoc (regset_bytes);
1329 bzero ((char *) regs_live_at_setjmp, regset_bytes);
1332 /* Make each element of VECTOR point at a regset,
1333 taking the space for all those regsets from SPACE.
1334 SPACE is of type regset, but it is really as long as NELTS regsets.
1335 BYTES_PER_ELT is the number of bytes in one regset. */
1338 init_regset_vector (vector, space, nelts, bytes_per_elt)
1345 register regset p = space;
1347 for (i = 0; i < nelts; i++)
1350 p += bytes_per_elt / sizeof (*p);
1354 /* Compute the registers live at the beginning of a basic block
1355 from those live at the end.
1357 When called, OLD contains those live at the end.
1358 On return, it contains those live at the beginning.
1359 FIRST and LAST are the first and last insns of the basic block.
1361 FINAL is nonzero if we are doing the final pass which is not
1362 for computing the life info (since that has already been done)
1363 but for acting on it. On this pass, we delete dead stores,
1364 set up the logical links and dead-variables lists of instructions,
1365 and merge instructions for autoincrement and autodecrement addresses.
1367 SIGNIFICANT is nonzero only the first time for each basic block.
1368 If it is nonzero, it points to a regset in which we store
1369 a 1 for each register that is set within the block.
1371 BNUM is the number of the basic block. */
1374 propagate_block (old, first, last, final, significant, bnum)
1375 register regset old;
1387 /* The following variables are used only if FINAL is nonzero. */
1388 /* This vector gets one element for each reg that has been live
1389 at any point in the basic block that has been scanned so far.
1390 SOMETIMES_MAX says how many elements are in use so far.
1391 In each element, OFFSET is the byte-number within a regset
1392 for the register described by the element, and BIT is a mask
1393 for that register's bit within the byte. */
1394 register struct sometimes { short offset; short bit; } *regs_sometimes_live;
1395 int sometimes_max = 0;
1396 /* This regset has 1 for each reg that we have seen live so far.
1397 It and REGS_SOMETIMES_LIVE are updated together. */
1400 /* The loop depth may change in the middle of a basic block. Since we
1401 scan from end to beginning, we start with the depth at the end of the
1402 current basic block, and adjust as we pass ends and starts of loops. */
1403 loop_depth = basic_block_loop_depth[bnum];
1405 dead = (regset) alloca (regset_bytes);
1406 live = (regset) alloca (regset_bytes);
1411 /* Include any notes at the end of the block in the scan.
1412 This is in case the block ends with a call to setjmp. */
1414 while (NEXT_INSN (last) != 0 && GET_CODE (NEXT_INSN (last)) == NOTE)
1416 /* Look for loop boundaries, we are going forward here. */
1417 last = NEXT_INSN (last);
1418 if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_BEG)
1420 else if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_END)
1426 register int i, offset;
1427 REGSET_ELT_TYPE bit;
1430 maxlive = (regset) alloca (regset_bytes);
1431 bcopy ((char *) old, (char *) maxlive, regset_bytes);
1433 = (struct sometimes *) alloca (max_regno * sizeof (struct sometimes));
1435 /* Process the regs live at the end of the block.
1436 Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
1437 Also mark them as not local to any one basic block. */
1439 for (offset = 0, i = 0; offset < regset_size; offset++)
1440 for (bit = 1; bit; bit <<= 1, i++)
1444 if (old[offset] & bit)
1446 reg_basic_block[i] = REG_BLOCK_GLOBAL;
1447 regs_sometimes_live[sometimes_max].offset = offset;
1448 regs_sometimes_live[sometimes_max].bit = i % REGSET_ELT_BITS;
1454 /* Scan the block an insn at a time from end to beginning. */
1456 for (insn = last; ; insn = prev)
1458 prev = PREV_INSN (insn);
1460 if (GET_CODE (insn) == NOTE)
1462 /* Look for loop boundaries, remembering that we are going
1464 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1466 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1469 /* If we have LOOP_DEPTH == 0, there has been a bookkeeping error.
1470 Abort now rather than setting register status incorrectly. */
1471 if (loop_depth == 0)
1474 /* If this is a call to `setjmp' et al,
1475 warn if any non-volatile datum is live. */
1477 if (final && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
1480 for (i = 0; i < regset_size; i++)
1481 regs_live_at_setjmp[i] |= old[i];
1485 /* Update the life-status of regs for this insn.
1486 First DEAD gets which regs are set in this insn
1487 then LIVE gets which regs are used in this insn.
1488 Then the regs live before the insn
1489 are those live after, with DEAD regs turned off,
1490 and then LIVE regs turned on. */
1492 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
1495 rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1497 = (insn_dead_p (PATTERN (insn), old, 0)
1498 /* Don't delete something that refers to volatile storage! */
1499 && ! INSN_VOLATILE (insn));
1501 = (insn_is_dead && note != 0
1502 && libcall_dead_p (PATTERN (insn), old, note, insn));
1504 /* If an instruction consists of just dead store(s) on final pass,
1505 "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
1506 We could really delete it with delete_insn, but that
1507 can cause trouble for first or last insn in a basic block. */
1508 if (final && insn_is_dead)
1510 PUT_CODE (insn, NOTE);
1511 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
1512 NOTE_SOURCE_FILE (insn) = 0;
1514 /* CC0 is now known to be dead. Either this insn used it,
1515 in which case it doesn't anymore, or clobbered it,
1516 so the next insn can't use it. */
1519 /* If this insn is copying the return value from a library call,
1520 delete the entire library call. */
1521 if (libcall_is_dead)
1523 rtx first = XEXP (note, 0);
1525 while (INSN_DELETED_P (first))
1526 first = NEXT_INSN (first);
1531 NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED;
1532 NOTE_SOURCE_FILE (p) = 0;
1538 for (i = 0; i < regset_size; i++)
1540 dead[i] = 0; /* Faster than bzero here */
1541 live[i] = 0; /* since regset_size is usually small */
1544 /* See if this is an increment or decrement that can be
1545 merged into a following memory address. */
1548 register rtx x = PATTERN (insn);
1549 /* Does this instruction increment or decrement a register? */
1550 if (final && GET_CODE (x) == SET
1551 && GET_CODE (SET_DEST (x)) == REG
1552 && (GET_CODE (SET_SRC (x)) == PLUS
1553 || GET_CODE (SET_SRC (x)) == MINUS)
1554 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1555 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1556 /* Ok, look for a following memory ref we can combine with.
1557 If one is found, change the memory ref to a PRE_INC
1558 or PRE_DEC, cancel this insn, and return 1.
1559 Return 0 if nothing has been done. */
1560 && try_pre_increment_1 (insn))
1563 #endif /* AUTO_INC_DEC */
1565 /* If this is not the final pass, and this insn is copying the
1566 value of a library call and it's dead, don't scan the
1567 insns that perform the library call, so that the call's
1568 arguments are not marked live. */
1569 if (libcall_is_dead)
1571 /* Mark the dest reg as `significant'. */
1572 mark_set_regs (old, dead, PATTERN (insn), NULL_RTX, significant);
1574 insn = XEXP (note, 0);
1575 prev = PREV_INSN (insn);
1577 else if (GET_CODE (PATTERN (insn)) == SET
1578 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1579 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1580 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1581 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1582 /* We have an insn to pop a constant amount off the stack.
1583 (Such insns use PLUS regardless of the direction of the stack,
1584 and any insn to adjust the stack by a constant is always a pop.)
1585 These insns, if not dead stores, have no effect on life. */
1589 /* LIVE gets the regs used in INSN;
1590 DEAD gets those set by it. Dead insns don't make anything
1593 mark_set_regs (old, dead, PATTERN (insn),
1594 final ? insn : NULL_RTX, significant);
1596 /* If an insn doesn't use CC0, it becomes dead since we
1597 assume that every insn clobbers it. So show it dead here;
1598 mark_used_regs will set it live if it is referenced. */
1602 mark_used_regs (old, live, PATTERN (insn), final, insn);
1604 /* Sometimes we may have inserted something before INSN (such as
1605 a move) when we make an auto-inc. So ensure we will scan
1608 prev = PREV_INSN (insn);
1611 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1617 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1619 note = XEXP (note, 1))
1620 if (GET_CODE (XEXP (note, 0)) == USE)
1621 mark_used_regs (old, live, SET_DEST (XEXP (note, 0)),
1624 /* Each call clobbers all call-clobbered regs that are not
1625 global or fixed. Note that the function-value reg is a
1626 call-clobbered reg, and mark_set_regs has already had
1627 a chance to handle it. */
1629 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1630 if (call_used_regs[i] && ! global_regs[i]
1632 dead[i / REGSET_ELT_BITS]
1633 |= ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS));
1635 /* The stack ptr is used (honorarily) by a CALL insn. */
1636 live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
1637 |= ((REGSET_ELT_TYPE) 1
1638 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS));
1640 /* Calls may also reference any of the global registers,
1641 so they are made live. */
1642 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1644 mark_used_regs (old, live,
1645 gen_rtx (REG, reg_raw_mode[i], i),
1648 /* Calls also clobber memory. */
1652 /* Update OLD for the registers used or set. */
1653 for (i = 0; i < regset_size; i++)
1659 if (GET_CODE (insn) == CALL_INSN && final)
1661 /* Any regs live at the time of a call instruction
1662 must not go in a register clobbered by calls.
1663 Find all regs now live and record this for them. */
1665 register struct sometimes *p = regs_sometimes_live;
1667 for (i = 0; i < sometimes_max; i++, p++)
1668 if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
1669 reg_n_calls_crossed[p->offset * REGSET_ELT_BITS + p->bit]+= 1;
1673 /* On final pass, add any additional sometimes-live regs
1674 into MAXLIVE and REGS_SOMETIMES_LIVE.
1675 Also update counts of how many insns each reg is live at. */
1679 for (i = 0; i < regset_size; i++)
1681 register REGSET_ELT_TYPE diff = live[i] & ~maxlive[i];
1687 for (regno = 0; diff && regno < REGSET_ELT_BITS; regno++)
1688 if (diff & ((REGSET_ELT_TYPE) 1 << regno))
1690 regs_sometimes_live[sometimes_max].offset = i;
1691 regs_sometimes_live[sometimes_max].bit = regno;
1692 diff &= ~ ((REGSET_ELT_TYPE) 1 << regno);
1699 register struct sometimes *p = regs_sometimes_live;
1700 for (i = 0; i < sometimes_max; i++, p++)
1702 if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
1703 reg_live_length[p->offset * REGSET_ELT_BITS + p->bit]++;
1713 if (num_scratch > max_scratch)
1714 max_scratch = num_scratch;
1717 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1718 (SET expressions whose destinations are registers dead after the insn).
1719 NEEDED is the regset that says which regs are alive after the insn.
1721 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */
1724 insn_dead_p (x, needed, call_ok)
1729 register RTX_CODE code = GET_CODE (x);
1730 /* If setting something that's a reg or part of one,
1731 see if that register's altered value will be live. */
1735 register rtx r = SET_DEST (x);
1736 /* A SET that is a subroutine call cannot be dead. */
1737 if (! call_ok && GET_CODE (SET_SRC (x)) == CALL)
1741 if (GET_CODE (r) == CC0)
1745 if (GET_CODE (r) == MEM && last_mem_set && ! MEM_VOLATILE_P (r)
1746 && rtx_equal_p (r, last_mem_set))
1749 while (GET_CODE (r) == SUBREG
1750 || GET_CODE (r) == STRICT_LOW_PART
1751 || GET_CODE (r) == ZERO_EXTRACT
1752 || GET_CODE (r) == SIGN_EXTRACT)
1755 if (GET_CODE (r) == REG)
1757 register int regno = REGNO (r);
1758 register int offset = regno / REGSET_ELT_BITS;
1759 register REGSET_ELT_TYPE bit
1760 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
1762 /* Don't delete insns to set global regs. */
1763 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
1764 /* Make sure insns to set frame pointer aren't deleted. */
1765 || regno == FRAME_POINTER_REGNUM
1766 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1767 || regno == HARD_FRAME_POINTER_REGNUM
1769 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1770 /* Make sure insns to set arg pointer are never deleted
1771 (if the arg pointer isn't fixed, there will be a USE for
1772 it, so we can treat it normally). */
1773 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1775 || (needed[offset] & bit) != 0)
1778 /* If this is a hard register, verify that subsequent words are
1780 if (regno < FIRST_PSEUDO_REGISTER)
1782 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
1785 if ((needed[(regno + n) / REGSET_ELT_BITS]
1786 & ((REGSET_ELT_TYPE) 1
1787 << ((regno + n) % REGSET_ELT_BITS))) != 0)
1794 /* If performing several activities,
1795 insn is dead if each activity is individually dead.
1796 Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
1797 that's inside a PARALLEL doesn't make the insn worth keeping. */
1798 else if (code == PARALLEL)
1800 register int i = XVECLEN (x, 0);
1801 for (i--; i >= 0; i--)
1803 rtx elt = XVECEXP (x, 0, i);
1804 if (!insn_dead_p (elt, needed, call_ok)
1805 && GET_CODE (elt) != CLOBBER
1806 && GET_CODE (elt) != USE)
1811 /* We do not check CLOBBER or USE here.
1812 An insn consisting of just a CLOBBER or just a USE
1813 should not be deleted. */
1817 /* If X is the pattern of the last insn in a libcall, and assuming X is dead,
1818 return 1 if the entire library call is dead.
1819 This is true if X copies a register (hard or pseudo)
1820 and if the hard return reg of the call insn is dead.
1821 (The caller should have tested the destination of X already for death.)
1823 If this insn doesn't just copy a register, then we don't
1824 have an ordinary libcall. In that case, cse could not have
1825 managed to substitute the source for the dest later on,
1826 so we can assume the libcall is dead.
1828 NEEDED is the bit vector of pseudoregs live before this insn.
1829 NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
1832 libcall_dead_p (x, needed, note, insn)
1838 register RTX_CODE code = GET_CODE (x);
1842 register rtx r = SET_SRC (x);
1843 if (GET_CODE (r) == REG)
1845 rtx call = XEXP (note, 0);
1848 /* Find the call insn. */
1849 while (call != insn && GET_CODE (call) != CALL_INSN)
1850 call = NEXT_INSN (call);
1852 /* If there is none, do nothing special,
1853 since ordinary death handling can understand these insns. */
1857 /* See if the hard reg holding the value is dead.
1858 If this is a PARALLEL, find the call within it. */
1859 call = PATTERN (call);
1860 if (GET_CODE (call) == PARALLEL)
1862 for (i = XVECLEN (call, 0) - 1; i >= 0; i--)
1863 if (GET_CODE (XVECEXP (call, 0, i)) == SET
1864 && GET_CODE (SET_SRC (XVECEXP (call, 0, i))) == CALL)
1867 /* This may be a library call that is returning a value
1868 via invisible pointer. Do nothing special, since
1869 ordinary death handling can understand these insns. */
1873 call = XVECEXP (call, 0, i);
1876 return insn_dead_p (call, needed, 1);
1882 /* Return 1 if register REGNO was used before it was set.
1883 In other words, if it is live at function entry.
1884 Don't count global register variables, though. */
1887 regno_uninitialized (regno)
1890 if (n_basic_blocks == 0
1891 || (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
1894 return (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1895 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS)));
1898 /* 1 if register REGNO was alive at a place where `setjmp' was called
1899 and was set more than once or is an argument.
1900 Such regs may be clobbered by `longjmp'. */
1903 regno_clobbered_at_setjmp (regno)
1906 if (n_basic_blocks == 0)
1909 return ((reg_n_sets[regno] > 1
1910 || (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1911 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))))
1912 && (regs_live_at_setjmp[regno / REGSET_ELT_BITS]
1913 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))));
1916 /* Process the registers that are set within X.
1917 Their bits are set to 1 in the regset DEAD,
1918 because they are dead prior to this insn.
1920 If INSN is nonzero, it is the insn being processed
1921 and the fact that it is nonzero implies this is the FINAL pass
1922 in propagate_block. In this case, various info about register
1923 usage is stored, LOG_LINKS fields of insns are set up. */
1926 mark_set_regs (needed, dead, x, insn, significant)
1933 register RTX_CODE code = GET_CODE (x);
1935 if (code == SET || code == CLOBBER)
1936 mark_set_1 (needed, dead, x, insn, significant);
1937 else if (code == PARALLEL)
1940 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
1942 code = GET_CODE (XVECEXP (x, 0, i));
1943 if (code == SET || code == CLOBBER)
1944 mark_set_1 (needed, dead, XVECEXP (x, 0, i), insn, significant);
1949 /* Process a single SET rtx, X. */
1952 mark_set_1 (needed, dead, x, insn, significant)
1960 register rtx reg = SET_DEST (x);
1962 /* Modifying just one hardware register of a multi-reg value
1963 or just a byte field of a register
1964 does not mean the value from before this insn is now dead.
1965 But it does mean liveness of that register at the end of the block
1968 Within mark_set_1, however, we treat it as if the register is
1969 indeed modified. mark_used_regs will, however, also treat this
1970 register as being used. Thus, we treat these insns as setting a
1971 new value for the register as a function of its old value. This
1972 cases LOG_LINKS to be made appropriately and this will help combine. */
1974 while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
1975 || GET_CODE (reg) == SIGN_EXTRACT
1976 || GET_CODE (reg) == STRICT_LOW_PART)
1977 reg = XEXP (reg, 0);
1979 /* If we are writing into memory or into a register mentioned in the
1980 address of the last thing stored into memory, show we don't know
1981 what the last store was. If we are writing memory, save the address
1982 unless it is volatile. */
1983 if (GET_CODE (reg) == MEM
1984 || (GET_CODE (reg) == REG
1985 && last_mem_set != 0 && reg_overlap_mentioned_p (reg, last_mem_set)))
1988 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
1989 /* There are no REG_INC notes for SP, so we can't assume we'll see
1990 everything that invalidates it. To be safe, don't eliminate any
1991 stores though SP; none of them should be redundant anyway. */
1992 && ! reg_mentioned_p (stack_pointer_rtx, reg))
1995 if (GET_CODE (reg) == REG
1996 && (regno = REGNO (reg), regno != FRAME_POINTER_REGNUM)
1997 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1998 && regno != HARD_FRAME_POINTER_REGNUM
2000 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2001 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2003 && ! (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
2004 /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
2006 register int offset = regno / REGSET_ELT_BITS;
2007 register REGSET_ELT_TYPE bit
2008 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2009 REGSET_ELT_TYPE all_needed = (needed[offset] & bit);
2010 REGSET_ELT_TYPE some_needed = (needed[offset] & bit);
2012 /* Mark it as a significant register for this basic block. */
2014 significant[offset] |= bit;
2016 /* Mark it as as dead before this insn. */
2017 dead[offset] |= bit;
2019 /* A hard reg in a wide mode may really be multiple registers.
2020 If so, mark all of them just like the first. */
2021 if (regno < FIRST_PSEUDO_REGISTER)
2025 /* Nothing below is needed for the stack pointer; get out asap.
2026 Eg, log links aren't needed, since combine won't use them. */
2027 if (regno == STACK_POINTER_REGNUM)
2030 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
2034 significant[(regno + n) / REGSET_ELT_BITS]
2035 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
2036 dead[(regno + n) / REGSET_ELT_BITS]
2037 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
2039 |= (needed[(regno + n) / REGSET_ELT_BITS]
2040 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2042 &= (needed[(regno + n) / REGSET_ELT_BITS]
2043 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2046 /* Additional data to record if this is the final pass. */
2049 register rtx y = reg_next_use[regno];
2050 register int blocknum = BLOCK_NUM (insn);
2052 /* If this is a hard reg, record this function uses the reg. */
2054 if (regno < FIRST_PSEUDO_REGISTER)
2057 int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg));
2059 for (i = regno; i < endregno; i++)
2061 /* The next use is no longer "next", since a store
2063 reg_next_use[i] = 0;
2065 regs_ever_live[i] = 1;
2071 /* The next use is no longer "next", since a store
2073 reg_next_use[regno] = 0;
2075 /* Keep track of which basic blocks each reg appears in. */
2077 if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
2078 reg_basic_block[regno] = blocknum;
2079 else if (reg_basic_block[regno] != blocknum)
2080 reg_basic_block[regno] = REG_BLOCK_GLOBAL;
2082 /* Count (weighted) references, stores, etc. This counts a
2083 register twice if it is modified, but that is correct. */
2084 reg_n_sets[regno]++;
2086 reg_n_refs[regno] += loop_depth;
2088 /* The insns where a reg is live are normally counted
2089 elsewhere, but we want the count to include the insn
2090 where the reg is set, and the normal counting mechanism
2091 would not count it. */
2092 reg_live_length[regno]++;
2097 /* Make a logical link from the next following insn
2098 that uses this register, back to this insn.
2099 The following insns have already been processed.
2101 We don't build a LOG_LINK for hard registers containing
2102 in ASM_OPERANDs. If these registers get replaced,
2103 we might wind up changing the semantics of the insn,
2104 even if reload can make what appear to be valid assignments
2106 if (y && (BLOCK_NUM (y) == blocknum)
2107 && (regno >= FIRST_PSEUDO_REGISTER
2108 || asm_noperands (PATTERN (y)) < 0))
2110 = gen_rtx (INSN_LIST, VOIDmode, insn, LOG_LINKS (y));
2112 else if (! some_needed)
2114 /* Note that dead stores have already been deleted when possible
2115 If we get here, we have found a dead store that cannot
2116 be eliminated (because the same insn does something useful).
2117 Indicate this by marking the reg being set as dying here. */
2119 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
2120 reg_n_deaths[REGNO (reg)]++;
2124 /* This is a case where we have a multi-word hard register
2125 and some, but not all, of the words of the register are
2126 needed in subsequent insns. Write REG_UNUSED notes
2127 for those parts that were not needed. This case should
2132 for (i = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1;
2134 if ((needed[(regno + i) / REGSET_ELT_BITS]
2135 & ((REGSET_ELT_TYPE) 1
2136 << ((regno + i) % REGSET_ELT_BITS))) == 0)
2138 = gen_rtx (EXPR_LIST, REG_UNUSED,
2139 gen_rtx (REG, reg_raw_mode[regno + i],
2145 else if (GET_CODE (reg) == REG)
2146 reg_next_use[regno] = 0;
2148 /* If this is the last pass and this is a SCRATCH, show it will be dying
2149 here and count it. */
2150 else if (GET_CODE (reg) == SCRATCH && insn != 0)
2153 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
2160 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
2164 find_auto_inc (needed, x, insn)
2169 rtx addr = XEXP (x, 0);
2170 HOST_WIDE_INT offset = 0;
2173 /* Here we detect use of an index register which might be good for
2174 postincrement, postdecrement, preincrement, or predecrement. */
2176 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
2177 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
2179 if (GET_CODE (addr) == REG)
2182 register int size = GET_MODE_SIZE (GET_MODE (x));
2185 int regno = REGNO (addr);
2187 /* Is the next use an increment that might make auto-increment? */
2188 if ((incr = reg_next_use[regno]) != 0
2189 && (set = single_set (incr)) != 0
2190 && GET_CODE (set) == SET
2191 && BLOCK_NUM (incr) == BLOCK_NUM (insn)
2192 /* Can't add side effects to jumps; if reg is spilled and
2193 reloaded, there's no way to store back the altered value. */
2194 && GET_CODE (insn) != JUMP_INSN
2195 && (y = SET_SRC (set), GET_CODE (y) == PLUS)
2196 && XEXP (y, 0) == addr
2197 && GET_CODE (XEXP (y, 1)) == CONST_INT
2199 #ifdef HAVE_POST_INCREMENT
2200 || (INTVAL (XEXP (y, 1)) == size && offset == 0)
2202 #ifdef HAVE_POST_DECREMENT
2203 || (INTVAL (XEXP (y, 1)) == - size && offset == 0)
2205 #ifdef HAVE_PRE_INCREMENT
2206 || (INTVAL (XEXP (y, 1)) == size && offset == size)
2208 #ifdef HAVE_PRE_DECREMENT
2209 || (INTVAL (XEXP (y, 1)) == - size && offset == - size)
2212 /* Make sure this reg appears only once in this insn. */
2213 && (use = find_use_as_address (PATTERN (insn), addr, offset),
2214 use != 0 && use != (rtx) 1))
2216 rtx q = SET_DEST (set);
2217 enum rtx_code inc_code = (INTVAL (XEXP (y, 1)) == size
2218 ? (offset ? PRE_INC : POST_INC)
2219 : (offset ? PRE_DEC : POST_DEC));
2221 if (dead_or_set_p (incr, addr))
2223 /* This is the simple case. Try to make the auto-inc. If
2224 we can't, we are done. Otherwise, we will do any
2225 needed updates below. */
2226 if (! validate_change (insn, &XEXP (x, 0),
2227 gen_rtx (inc_code, Pmode, addr),
2231 else if (GET_CODE (q) == REG
2232 /* PREV_INSN used here to check the semi-open interval
2234 && ! reg_used_between_p (q, PREV_INSN (insn), incr))
2236 /* We have *p followed sometime later by q = p+size.
2237 Both p and q must be live afterward,
2238 and q is not used between INSN and it's assignment.
2239 Change it to q = p, ...*q..., q = q+size.
2240 Then fall into the usual case. */
2244 emit_move_insn (q, addr);
2245 insns = get_insns ();
2248 /* If anything in INSNS have UID's that don't fit within the
2249 extra space we allocate earlier, we can't make this auto-inc.
2250 This should never happen. */
2251 for (temp = insns; temp; temp = NEXT_INSN (temp))
2253 if (INSN_UID (temp) > max_uid_for_flow)
2255 BLOCK_NUM (temp) = BLOCK_NUM (insn);
2258 /* If we can't make the auto-inc, or can't make the
2259 replacement into Y, exit. There's no point in making
2260 the change below if we can't do the auto-inc and doing
2261 so is not correct in the pre-inc case. */
2263 validate_change (insn, &XEXP (x, 0),
2264 gen_rtx (inc_code, Pmode, q),
2266 validate_change (incr, &XEXP (y, 0), q, 1);
2267 if (! apply_change_group ())
2270 /* We now know we'll be doing this change, so emit the
2271 new insn(s) and do the updates. */
2272 emit_insns_before (insns, insn);
2274 if (basic_block_head[BLOCK_NUM (insn)] == insn)
2275 basic_block_head[BLOCK_NUM (insn)] = insns;
2277 /* INCR will become a NOTE and INSN won't contain a
2278 use of ADDR. If a use of ADDR was just placed in
2279 the insn before INSN, make that the next use.
2280 Otherwise, invalidate it. */
2281 if (GET_CODE (PREV_INSN (insn)) == INSN
2282 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
2283 && SET_SRC (PATTERN (PREV_INSN (insn))) == addr)
2284 reg_next_use[regno] = PREV_INSN (insn);
2286 reg_next_use[regno] = 0;
2291 /* REGNO is now used in INCR which is below INSN, but
2292 it previously wasn't live here. If we don't mark
2293 it as needed, we'll put a REG_DEAD note for it
2294 on this insn, which is incorrect. */
2295 needed[regno / REGSET_ELT_BITS]
2296 |= (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2298 /* If there are any calls between INSN and INCR, show
2299 that REGNO now crosses them. */
2300 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
2301 if (GET_CODE (temp) == CALL_INSN)
2302 reg_n_calls_crossed[regno]++;
2307 /* If we haven't returned, it means we were able to make the
2308 auto-inc, so update the status. First, record that this insn
2309 has an implicit side effect. */
2312 = gen_rtx (EXPR_LIST, REG_INC, addr, REG_NOTES (insn));
2314 /* Modify the old increment-insn to simply copy
2315 the already-incremented value of our register. */
2316 if (! validate_change (incr, &SET_SRC (set), addr, 0))
2319 /* If that makes it a no-op (copying the register into itself) delete
2320 it so it won't appear to be a "use" and a "set" of this
2322 if (SET_DEST (set) == addr)
2324 PUT_CODE (incr, NOTE);
2325 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
2326 NOTE_SOURCE_FILE (incr) = 0;
2329 if (regno >= FIRST_PSEUDO_REGISTER)
2331 /* Count an extra reference to the reg. When a reg is
2332 incremented, spilling it is worse, so we want to make
2333 that less likely. */
2334 reg_n_refs[regno] += loop_depth;
2336 /* Count the increment as a setting of the register,
2337 even though it isn't a SET in rtl. */
2338 reg_n_sets[regno]++;
2343 #endif /* AUTO_INC_DEC */
2345 /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
2346 This is done assuming the registers needed from X
2347 are those that have 1-bits in NEEDED.
2349 On the final pass, FINAL is 1. This means try for autoincrement
2350 and count the uses and deaths of each pseudo-reg.
2352 INSN is the containing instruction. If INSN is dead, this function is not
2356 mark_used_regs (needed, live, x, final, insn)
2363 register RTX_CODE code;
2368 code = GET_CODE (x);
2389 /* If we are clobbering a MEM, mark any registers inside the address
2391 if (GET_CODE (XEXP (x, 0)) == MEM)
2392 mark_used_regs (needed, live, XEXP (XEXP (x, 0), 0), final, insn);
2396 /* Invalidate the data for the last MEM stored. We could do this only
2397 if the addresses conflict, but this doesn't seem worthwhile. */
2402 find_auto_inc (needed, x, insn);
2407 if (GET_CODE (SUBREG_REG (x)) == REG
2408 && REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
2409 && (GET_MODE_SIZE (GET_MODE (x))
2410 != GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))))
2411 reg_changes_size[REGNO (SUBREG_REG (x))] = 1;
2413 /* While we're here, optimize this case. */
2416 /* In case the SUBREG is not of a register, don't optimize */
2417 if (GET_CODE (x) != REG)
2419 mark_used_regs (needed, live, x, final, insn);
2423 /* ... fall through ... */
2426 /* See a register other than being set
2427 => mark it as needed. */
2431 register int offset = regno / REGSET_ELT_BITS;
2432 register REGSET_ELT_TYPE bit
2433 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2434 REGSET_ELT_TYPE all_needed = needed[offset] & bit;
2435 REGSET_ELT_TYPE some_needed = needed[offset] & bit;
2437 live[offset] |= bit;
2438 /* A hard reg in a wide mode may really be multiple registers.
2439 If so, mark all of them just like the first. */
2440 if (regno < FIRST_PSEUDO_REGISTER)
2444 /* For stack ptr or fixed arg pointer,
2445 nothing below can be necessary, so waste no more time. */
2446 if (regno == STACK_POINTER_REGNUM
2447 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2448 || regno == HARD_FRAME_POINTER_REGNUM
2450 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2451 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2453 || regno == FRAME_POINTER_REGNUM)
2455 /* If this is a register we are going to try to eliminate,
2456 don't mark it live here. If we are successful in
2457 eliminating it, it need not be live unless it is used for
2458 pseudos, in which case it will have been set live when
2459 it was allocated to the pseudos. If the register will not
2460 be eliminated, reload will set it live at that point. */
2462 if (! TEST_HARD_REG_BIT (elim_reg_set, regno))
2463 regs_ever_live[regno] = 1;
2466 /* No death notes for global register variables;
2467 their values are live after this function exits. */
2468 if (global_regs[regno])
2471 reg_next_use[regno] = insn;
2475 n = HARD_REGNO_NREGS (regno, GET_MODE (x));
2478 live[(regno + n) / REGSET_ELT_BITS]
2479 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
2481 |= (needed[(regno + n) / REGSET_ELT_BITS]
2482 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2484 &= (needed[(regno + n) / REGSET_ELT_BITS]
2485 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2490 /* Record where each reg is used, so when the reg
2491 is set we know the next insn that uses it. */
2493 reg_next_use[regno] = insn;
2495 if (regno < FIRST_PSEUDO_REGISTER)
2497 /* If a hard reg is being used,
2498 record that this function does use it. */
2500 i = HARD_REGNO_NREGS (regno, GET_MODE (x));
2504 regs_ever_live[regno + --i] = 1;
2509 /* Keep track of which basic block each reg appears in. */
2511 register int blocknum = BLOCK_NUM (insn);
2513 if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
2514 reg_basic_block[regno] = blocknum;
2515 else if (reg_basic_block[regno] != blocknum)
2516 reg_basic_block[regno] = REG_BLOCK_GLOBAL;
2518 /* Count (weighted) number of uses of each reg. */
2520 reg_n_refs[regno] += loop_depth;
2523 /* Record and count the insns in which a reg dies.
2524 If it is used in this insn and was dead below the insn
2525 then it dies in this insn. If it was set in this insn,
2526 we do not make a REG_DEAD note; likewise if we already
2527 made such a note. */
2530 && ! dead_or_set_p (insn, x)
2532 && (regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
2536 /* Check for the case where the register dying partially
2537 overlaps the register set by this insn. */
2538 if (regno < FIRST_PSEUDO_REGISTER
2539 && HARD_REGNO_NREGS (regno, GET_MODE (x)) > 1)
2541 int n = HARD_REGNO_NREGS (regno, GET_MODE (x));
2543 some_needed |= dead_or_set_regno_p (insn, regno + n);
2546 /* If none of the words in X is needed, make a REG_DEAD
2547 note. Otherwise, we must make partial REG_DEAD notes. */
2551 = gen_rtx (EXPR_LIST, REG_DEAD, x, REG_NOTES (insn));
2552 reg_n_deaths[regno]++;
2558 /* Don't make a REG_DEAD note for a part of a register
2559 that is set in the insn. */
2561 for (i = HARD_REGNO_NREGS (regno, GET_MODE (x)) - 1;
2563 if ((needed[(regno + i) / REGSET_ELT_BITS]
2564 & ((REGSET_ELT_TYPE) 1
2565 << ((regno + i) % REGSET_ELT_BITS))) == 0
2566 && ! dead_or_set_regno_p (insn, regno + i))
2568 = gen_rtx (EXPR_LIST, REG_DEAD,
2569 gen_rtx (REG, reg_raw_mode[regno + i],
2580 register rtx testreg = SET_DEST (x);
2583 /* If storing into MEM, don't show it as being used. But do
2584 show the address as being used. */
2585 if (GET_CODE (testreg) == MEM)
2589 find_auto_inc (needed, testreg, insn);
2591 mark_used_regs (needed, live, XEXP (testreg, 0), final, insn);
2592 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2596 /* Storing in STRICT_LOW_PART is like storing in a reg
2597 in that this SET might be dead, so ignore it in TESTREG.
2598 but in some other ways it is like using the reg.
2600 Storing in a SUBREG or a bit field is like storing the entire
2601 register in that if the register's value is not used
2602 then this SET is not needed. */
2603 while (GET_CODE (testreg) == STRICT_LOW_PART
2604 || GET_CODE (testreg) == ZERO_EXTRACT
2605 || GET_CODE (testreg) == SIGN_EXTRACT
2606 || GET_CODE (testreg) == SUBREG)
2608 if (GET_CODE (testreg) == SUBREG
2609 && GET_CODE (SUBREG_REG (testreg)) == REG
2610 && REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
2611 && (GET_MODE_SIZE (GET_MODE (testreg))
2612 != GET_MODE_SIZE (GET_MODE (SUBREG_REG (testreg)))))
2613 reg_changes_size[REGNO (SUBREG_REG (testreg))] = 1;
2615 /* Modifying a single register in an alternate mode
2616 does not use any of the old value. But these other
2617 ways of storing in a register do use the old value. */
2618 if (GET_CODE (testreg) == SUBREG
2619 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
2624 testreg = XEXP (testreg, 0);
2627 /* If this is a store into a register,
2628 recursively scan the value being stored. */
2630 if (GET_CODE (testreg) == REG
2631 && (regno = REGNO (testreg), regno != FRAME_POINTER_REGNUM)
2632 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2633 && regno != HARD_FRAME_POINTER_REGNUM
2635 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2636 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2639 /* We used to exclude global_regs here, but that seems wrong.
2640 Storing in them is like storing in mem. */
2642 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2644 mark_used_regs (needed, live, SET_DEST (x), final, insn);
2651 /* If exiting needs the right stack value, consider this insn as
2652 using the stack pointer. In any event, consider it as using
2653 all global registers. */
2655 #ifdef EXIT_IGNORE_STACK
2656 if (! EXIT_IGNORE_STACK
2657 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
2659 live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
2660 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
2662 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2664 live[i / REGSET_ELT_BITS]
2665 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
2669 /* Recursively scan the operands of this expression. */
2672 register char *fmt = GET_RTX_FORMAT (code);
2675 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2679 /* Tail recursive case: save a function call level. */
2685 mark_used_regs (needed, live, XEXP (x, i), final, insn);
2687 else if (fmt[i] == 'E')
2690 for (j = 0; j < XVECLEN (x, i); j++)
2691 mark_used_regs (needed, live, XVECEXP (x, i, j), final, insn);
2700 try_pre_increment_1 (insn)
2703 /* Find the next use of this reg. If in same basic block,
2704 make it do pre-increment or pre-decrement if appropriate. */
2705 rtx x = PATTERN (insn);
2706 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
2707 * INTVAL (XEXP (SET_SRC (x), 1)));
2708 int regno = REGNO (SET_DEST (x));
2709 rtx y = reg_next_use[regno];
2711 && BLOCK_NUM (y) == BLOCK_NUM (insn)
2712 /* Don't do this if the reg dies, or gets set in y; a standard addressing
2713 mode would be better. */
2714 && ! dead_or_set_p (y, SET_DEST (x))
2715 && try_pre_increment (y, SET_DEST (PATTERN (insn)),
2718 /* We have found a suitable auto-increment
2719 and already changed insn Y to do it.
2720 So flush this increment-instruction. */
2721 PUT_CODE (insn, NOTE);
2722 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
2723 NOTE_SOURCE_FILE (insn) = 0;
2724 /* Count a reference to this reg for the increment
2725 insn we are deleting. When a reg is incremented.
2726 spilling it is worse, so we want to make that
2728 if (regno >= FIRST_PSEUDO_REGISTER)
2730 reg_n_refs[regno] += loop_depth;
2731 reg_n_sets[regno]++;
2738 /* Try to change INSN so that it does pre-increment or pre-decrement
2739 addressing on register REG in order to add AMOUNT to REG.
2740 AMOUNT is negative for pre-decrement.
2741 Returns 1 if the change could be made.
2742 This checks all about the validity of the result of modifying INSN. */
2745 try_pre_increment (insn, reg, amount)
2747 HOST_WIDE_INT amount;
2751 /* Nonzero if we can try to make a pre-increment or pre-decrement.
2752 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
2754 /* Nonzero if we can try to make a post-increment or post-decrement.
2755 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
2756 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
2757 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
2760 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
2763 /* From the sign of increment, see which possibilities are conceivable
2764 on this target machine. */
2765 #ifdef HAVE_PRE_INCREMENT
2769 #ifdef HAVE_POST_INCREMENT
2774 #ifdef HAVE_PRE_DECREMENT
2778 #ifdef HAVE_POST_DECREMENT
2783 if (! (pre_ok || post_ok))
2786 /* It is not safe to add a side effect to a jump insn
2787 because if the incremented register is spilled and must be reloaded
2788 there would be no way to store the incremented value back in memory. */
2790 if (GET_CODE (insn) == JUMP_INSN)
2795 use = find_use_as_address (PATTERN (insn), reg, 0);
2796 if (post_ok && (use == 0 || use == (rtx) 1))
2798 use = find_use_as_address (PATTERN (insn), reg, -amount);
2802 if (use == 0 || use == (rtx) 1)
2805 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
2808 /* See if this combination of instruction and addressing mode exists. */
2809 if (! validate_change (insn, &XEXP (use, 0),
2811 ? (do_post ? POST_INC : PRE_INC)
2812 : (do_post ? POST_DEC : PRE_DEC),
2816 /* Record that this insn now has an implicit side effect on X. */
2817 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_INC, reg, REG_NOTES (insn));
2821 #endif /* AUTO_INC_DEC */
2823 /* Find the place in the rtx X where REG is used as a memory address.
2824 Return the MEM rtx that so uses it.
2825 If PLUSCONST is nonzero, search instead for a memory address equivalent to
2826 (plus REG (const_int PLUSCONST)).
2828 If such an address does not appear, return 0.
2829 If REG appears more than once, or is used other than in such an address,
2833 find_use_as_address (x, reg, plusconst)
2836 HOST_WIDE_INT plusconst;
2838 enum rtx_code code = GET_CODE (x);
2839 char *fmt = GET_RTX_FORMAT (code);
2841 register rtx value = 0;
2844 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
2847 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
2848 && XEXP (XEXP (x, 0), 0) == reg
2849 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
2850 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
2853 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
2855 /* If REG occurs inside a MEM used in a bit-field reference,
2856 that is unacceptable. */
2857 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
2858 return (rtx) (HOST_WIDE_INT) 1;
2862 return (rtx) (HOST_WIDE_INT) 1;
2864 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2868 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
2872 return (rtx) (HOST_WIDE_INT) 1;
2877 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
2879 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
2883 return (rtx) (HOST_WIDE_INT) 1;
2891 /* Write information about registers and basic blocks into FILE.
2892 This is part of making a debugging dump. */
2895 dump_flow_info (file)
2899 static char *reg_class_names[] = REG_CLASS_NAMES;
2901 fprintf (file, "%d registers.\n", max_regno);
2903 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
2906 enum reg_class class, altclass;
2907 fprintf (file, "\nRegister %d used %d times across %d insns",
2908 i, reg_n_refs[i], reg_live_length[i]);
2909 if (reg_basic_block[i] >= 0)
2910 fprintf (file, " in block %d", reg_basic_block[i]);
2911 if (reg_n_deaths[i] != 1)
2912 fprintf (file, "; dies in %d places", reg_n_deaths[i]);
2913 if (reg_n_calls_crossed[i] == 1)
2914 fprintf (file, "; crosses 1 call");
2915 else if (reg_n_calls_crossed[i])
2916 fprintf (file, "; crosses %d calls", reg_n_calls_crossed[i]);
2917 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
2918 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
2919 class = reg_preferred_class (i);
2920 altclass = reg_alternate_class (i);
2921 if (class != GENERAL_REGS || altclass != ALL_REGS)
2923 if (altclass == ALL_REGS || class == ALL_REGS)
2924 fprintf (file, "; pref %s", reg_class_names[(int) class]);
2925 else if (altclass == NO_REGS)
2926 fprintf (file, "; %s or none", reg_class_names[(int) class]);
2928 fprintf (file, "; pref %s, else %s",
2929 reg_class_names[(int) class],
2930 reg_class_names[(int) altclass]);
2932 if (REGNO_POINTER_FLAG (i))
2933 fprintf (file, "; pointer");
2934 fprintf (file, ".\n");
2936 fprintf (file, "\n%d basic blocks.\n", n_basic_blocks);
2937 for (i = 0; i < n_basic_blocks; i++)
2939 register rtx head, jump;
2941 fprintf (file, "\nBasic block %d: first insn %d, last %d.\n",
2943 INSN_UID (basic_block_head[i]),
2944 INSN_UID (basic_block_end[i]));
2945 /* The control flow graph's storage is freed
2946 now when flow_analysis returns.
2947 Don't try to print it if it is gone. */
2948 if (basic_block_drops_in)
2950 fprintf (file, "Reached from blocks: ");
2951 head = basic_block_head[i];
2952 if (GET_CODE (head) == CODE_LABEL)
2953 for (jump = LABEL_REFS (head);
2955 jump = LABEL_NEXTREF (jump))
2957 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
2958 fprintf (file, " %d", from_block);
2960 if (basic_block_drops_in[i])
2961 fprintf (file, " previous");
2963 fprintf (file, "\nRegisters live at start:");
2964 for (regno = 0; regno < max_regno; regno++)
2966 register int offset = regno / REGSET_ELT_BITS;
2967 register REGSET_ELT_TYPE bit
2968 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2969 if (basic_block_live_at_start[i][offset] & bit)
2970 fprintf (file, " %d", regno);
2972 fprintf (file, "\n");
2974 fprintf (file, "\n");