1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992 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 short *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 short *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-alloc.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 ();
283 static void life_analysis ();
284 static void mark_label_ref ();
285 void allocate_for_life_analysis (); /* Used also in stupid_life_analysis */
286 static void init_regset_vector ();
287 static void propagate_block ();
288 static void mark_set_regs ();
289 static void mark_used_regs ();
290 static int insn_dead_p ();
291 static int libcall_dead_p ();
292 static int try_pre_increment ();
293 static int try_pre_increment_1 ();
294 static rtx find_use_as_address ();
295 void dump_flow_info ();
297 /* Find basic blocks of the current function and perform data flow analysis.
298 F is the first insn of the function and NREGS the number of register numbers
302 flow_analysis (f, nregs, file)
309 rtx nonlocal_label_list = nonlocal_label_rtx_list ();
311 #ifdef ELIMINABLE_REGS
312 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
315 /* Record which registers will be eliminated. We use this in
318 CLEAR_HARD_REG_SET (elim_reg_set);
320 #ifdef ELIMINABLE_REGS
321 for (i = 0; i < sizeof eliminables / sizeof eliminables[0]; i++)
322 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
324 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
327 /* Count the basic blocks. Also find maximum insn uid value used. */
330 register RTX_CODE prev_code = JUMP_INSN;
331 register RTX_CODE code;
333 max_uid_for_flow = 0;
335 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
337 code = GET_CODE (insn);
338 if (INSN_UID (insn) > max_uid_for_flow)
339 max_uid_for_flow = INSN_UID (insn);
340 if (code == CODE_LABEL
341 || (GET_RTX_CLASS (code) == 'i'
342 && (prev_code == JUMP_INSN
343 || (prev_code == CALL_INSN
344 && nonlocal_label_list != 0)
345 || prev_code == BARRIER)))
353 /* Leave space for insns we make in some cases for auto-inc. These cases
354 are rare, so we don't need too much space. */
355 max_uid_for_flow += max_uid_for_flow / 10;
358 /* Allocate some tables that last till end of compiling this function
359 and some needed only in find_basic_blocks and life_analysis. */
362 basic_block_head = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
363 basic_block_end = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
364 basic_block_drops_in = (char *) alloca (n_basic_blocks);
365 basic_block_loop_depth = (short *) alloca (n_basic_blocks * sizeof (short));
367 = (short *) alloca ((max_uid_for_flow + 1) * sizeof (short));
368 uid_volatile = (char *) alloca (max_uid_for_flow + 1);
369 bzero (uid_volatile, max_uid_for_flow + 1);
371 find_basic_blocks (f, nonlocal_label_list);
372 life_analysis (f, nregs);
374 dump_flow_info (file);
376 basic_block_drops_in = 0;
377 uid_block_number = 0;
378 basic_block_loop_depth = 0;
381 /* Find all basic blocks of the function whose first insn is F.
382 Store the correct data in the tables that describe the basic blocks,
383 set up the chains of references for each CODE_LABEL, and
384 delete any entire basic blocks that cannot be reached.
386 NONLOCAL_LABEL_LIST is the same local variable from flow_analysis. */
389 find_basic_blocks (f, nonlocal_label_list)
390 rtx f, nonlocal_label_list;
394 register char *block_live = (char *) alloca (n_basic_blocks);
395 register char *block_marked = (char *) alloca (n_basic_blocks);
396 /* List of label_refs to all labels whose addresses are taken
398 rtx label_value_list = 0;
400 block_live_static = block_live;
401 bzero (block_live, n_basic_blocks);
402 bzero (block_marked, n_basic_blocks);
404 /* Initialize with just block 0 reachable and no blocks marked. */
405 if (n_basic_blocks > 0)
408 /* Initialize the ref chain of each label to 0. */
409 /* Record where all the blocks start and end and their depth in loops. */
410 /* For each insn, record the block it is in. */
411 /* Also mark as reachable any blocks headed by labels that
412 must not be deleted. */
415 register RTX_CODE prev_code = JUMP_INSN;
416 register RTX_CODE code;
419 for (insn = f, i = -1; insn; insn = NEXT_INSN (insn))
421 code = GET_CODE (insn);
424 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
426 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
429 /* A basic block starts at label, or after something that can jump. */
430 else if (code == CODE_LABEL
431 || (GET_RTX_CLASS (code) == 'i'
432 && (prev_code == JUMP_INSN
433 || (prev_code == CALL_INSN
434 && nonlocal_label_list != 0)
435 || prev_code == BARRIER)))
437 basic_block_head[++i] = insn;
438 basic_block_end[i] = insn;
439 basic_block_loop_depth[i] = depth;
440 if (code == CODE_LABEL)
442 LABEL_REFS (insn) = insn;
443 /* Any label that cannot be deleted
444 is considered to start a reachable block. */
445 if (LABEL_PRESERVE_P (insn))
449 else if (GET_RTX_CLASS (code) == 'i')
451 basic_block_end[i] = insn;
452 basic_block_loop_depth[i] = depth;
455 /* Make a list of all labels referred to other than by jumps. */
456 if (code == INSN || code == CALL_INSN)
458 rtx note = find_reg_note (insn, REG_LABEL, NULL_RTX);
460 label_value_list = gen_rtx (EXPR_LIST, VOIDmode, XEXP (note, 0),
464 BLOCK_NUM (insn) = i;
466 /* Don't separate a CALL_INSN from following CLOBBER insns. This is
467 a kludge that will go away when each CALL_INSN records its
471 && ! (prev_code == CALL_INSN && code == INSN
472 && GET_CODE (PATTERN (insn)) == CLOBBER))
475 if (i + 1 != n_basic_blocks)
479 /* Don't delete the labels that are referenced by non-jump instructions. */
482 for (x = label_value_list; x; x = XEXP (x, 1))
483 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
486 /* Record which basic blocks control can drop in to. */
490 for (i = 0; i < n_basic_blocks; i++)
492 register rtx insn = PREV_INSN (basic_block_head[i]);
493 /* TEMP1 is used to avoid a bug in Sequent's compiler. */
495 while (insn && GET_CODE (insn) == NOTE)
496 insn = PREV_INSN (insn);
497 temp1 = insn && GET_CODE (insn) != BARRIER;
498 basic_block_drops_in[i] = temp1;
502 /* Now find which basic blocks can actually be reached
503 and put all jump insns' LABEL_REFS onto the ref-chains
504 of their target labels. */
506 if (n_basic_blocks > 0)
508 int something_marked = 1;
510 /* Find all indirect jump insns and mark them as possibly jumping
511 to all the labels whose addresses are explicitly used.
512 This is because, when there are computed gotos,
513 we can't tell which labels they jump to, of all the possibilities. */
515 for (insn = f; insn; insn = NEXT_INSN (insn))
516 if (GET_CODE (insn) == JUMP_INSN
517 && GET_CODE (PATTERN (insn)) == SET
518 && SET_DEST (PATTERN (insn)) == pc_rtx
519 && (GET_CODE (SET_SRC (PATTERN (insn))) == REG
520 || GET_CODE (SET_SRC (PATTERN (insn))) == MEM))
523 for (x = label_value_list; x; x = XEXP (x, 1))
524 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
526 for (x = forced_labels; x; x = XEXP (x, 1))
527 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
531 /* Find all call insns and mark them as possibly jumping
532 to all the nonlocal goto handler labels. */
534 for (insn = f; insn; insn = NEXT_INSN (insn))
535 if (GET_CODE (insn) == CALL_INSN)
538 for (x = nonlocal_label_list; x; x = XEXP (x, 1))
539 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
541 /* ??? This could be made smarter:
542 in some cases it's possible to tell that certain
543 calls will not do a nonlocal goto.
545 For example, if the nested functions that do the
546 nonlocal gotos do not have their addresses taken, then
547 only calls to those functions or to other nested
548 functions that use them could possibly do nonlocal
552 /* Pass over all blocks, marking each block that is reachable
553 and has not yet been marked.
554 Keep doing this until, in one pass, no blocks have been marked.
555 Then blocks_live and blocks_marked are identical and correct.
556 In addition, all jumps actually reachable have been marked. */
558 while (something_marked)
560 something_marked = 0;
561 for (i = 0; i < n_basic_blocks; i++)
562 if (block_live[i] && !block_marked[i])
565 something_marked = 1;
566 if (i + 1 < n_basic_blocks && basic_block_drops_in[i + 1])
567 block_live[i + 1] = 1;
568 insn = basic_block_end[i];
569 if (GET_CODE (insn) == JUMP_INSN)
570 mark_label_ref (PATTERN (insn), insn, 0);
574 /* Now delete the code for any basic blocks that can't be reached.
575 They can occur because jump_optimize does not recognize
576 unreachable loops as unreachable. */
578 for (i = 0; i < n_basic_blocks; i++)
581 insn = basic_block_head[i];
584 if (GET_CODE (insn) == BARRIER)
586 if (GET_CODE (insn) != NOTE)
588 PUT_CODE (insn, NOTE);
589 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
590 NOTE_SOURCE_FILE (insn) = 0;
592 if (insn == basic_block_end[i])
594 /* BARRIERs are between basic blocks, not part of one.
595 Delete a BARRIER if the preceding jump is deleted.
596 We cannot alter a BARRIER into a NOTE
597 because it is too short; but we can really delete
598 it because it is not part of a basic block. */
599 if (NEXT_INSN (insn) != 0
600 && GET_CODE (NEXT_INSN (insn)) == BARRIER)
601 delete_insn (NEXT_INSN (insn));
604 insn = NEXT_INSN (insn);
606 /* Each time we delete some basic blocks,
607 see if there is a jump around them that is
608 being turned into a no-op. If so, delete it. */
610 if (block_live[i - 1])
613 for (j = i; j < n_basic_blocks; j++)
617 insn = basic_block_end[i - 1];
618 if (GET_CODE (insn) == JUMP_INSN
619 /* An unconditional jump is the only possibility
620 we must check for, since a conditional one
621 would make these blocks live. */
622 && simplejump_p (insn)
623 && (label = XEXP (SET_SRC (PATTERN (insn)), 0), 1)
624 && INSN_UID (label) != 0
625 && BLOCK_NUM (label) == j)
627 PUT_CODE (insn, NOTE);
628 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
629 NOTE_SOURCE_FILE (insn) = 0;
630 if (GET_CODE (NEXT_INSN (insn)) != BARRIER)
632 delete_insn (NEXT_INSN (insn));
641 /* Check expression X for label references;
642 if one is found, add INSN to the label's chain of references.
644 CHECKDUP means check for and avoid creating duplicate references
645 from the same insn. Such duplicates do no serious harm but
646 can slow life analysis. CHECKDUP is set only when duplicates
650 mark_label_ref (x, insn, checkdup)
654 register RTX_CODE code;
658 /* We can be called with NULL when scanning label_value_list. */
663 if (code == LABEL_REF)
665 register rtx label = XEXP (x, 0);
667 if (GET_CODE (label) != CODE_LABEL)
669 /* If the label was never emitted, this insn is junk,
670 but avoid a crash trying to refer to BLOCK_NUM (label).
671 This can happen as a result of a syntax error
672 and a diagnostic has already been printed. */
673 if (INSN_UID (label) == 0)
675 CONTAINING_INSN (x) = insn;
676 /* if CHECKDUP is set, check for duplicate ref from same insn
679 for (y = LABEL_REFS (label); y != label; y = LABEL_NEXTREF (y))
680 if (CONTAINING_INSN (y) == insn)
682 LABEL_NEXTREF (x) = LABEL_REFS (label);
683 LABEL_REFS (label) = x;
684 block_live_static[BLOCK_NUM (label)] = 1;
688 fmt = GET_RTX_FORMAT (code);
689 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
692 mark_label_ref (XEXP (x, i), insn, 0);
696 for (j = 0; j < XVECLEN (x, i); j++)
697 mark_label_ref (XVECEXP (x, i, j), insn, 1);
702 /* Determine which registers are live at the start of each
703 basic block of the function whose first insn is F.
704 NREGS is the number of registers used in F.
705 We allocate the vector basic_block_live_at_start
706 and the regsets that it points to, and fill them with the data.
707 regset_size and regset_bytes are also set here. */
710 life_analysis (f, nregs)
717 /* For each basic block, a bitmask of regs
718 live on exit from the block. */
719 regset *basic_block_live_at_end;
720 /* For each basic block, a bitmask of regs
721 live on entry to a successor-block of this block.
722 If this does not match basic_block_live_at_end,
723 that must be updated, and the block must be rescanned. */
724 regset *basic_block_new_live_at_end;
725 /* For each basic block, a bitmask of regs
726 whose liveness at the end of the basic block
727 can make a difference in which regs are live on entry to the block.
728 These are the regs that are set within the basic block,
729 possibly excluding those that are used after they are set. */
730 regset *basic_block_significant;
734 struct obstack flow_obstack;
736 gcc_obstack_init (&flow_obstack);
740 bzero (regs_ever_live, sizeof regs_ever_live);
742 /* Allocate and zero out many data structures
743 that will record the data from lifetime analysis. */
745 allocate_for_life_analysis ();
747 reg_next_use = (rtx *) alloca (nregs * sizeof (rtx));
748 bzero (reg_next_use, nregs * sizeof (rtx));
750 /* Set up several regset-vectors used internally within this function.
751 Their meanings are documented above, with their declarations. */
753 basic_block_live_at_end = (regset *) alloca (n_basic_blocks * sizeof (regset));
754 /* Don't use alloca since that leads to a crash rather than an error message
755 if there isn't enough space.
756 Don't use oballoc since we may need to allocate other things during
757 this function on the temporary obstack. */
758 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
759 bzero (tem, n_basic_blocks * regset_bytes);
760 init_regset_vector (basic_block_live_at_end, tem, n_basic_blocks, regset_bytes);
762 basic_block_new_live_at_end = (regset *) alloca (n_basic_blocks * sizeof (regset));
763 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
764 bzero (tem, n_basic_blocks * regset_bytes);
765 init_regset_vector (basic_block_new_live_at_end, tem, n_basic_blocks, regset_bytes);
767 basic_block_significant = (regset *) alloca (n_basic_blocks * sizeof (regset));
768 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
769 bzero (tem, n_basic_blocks * regset_bytes);
770 init_regset_vector (basic_block_significant, tem, n_basic_blocks, regset_bytes);
772 /* Record which insns refer to any volatile memory
773 or for any reason can't be deleted just because they are dead stores.
774 Also, delete any insns that copy a register to itself. */
776 for (insn = f; insn; insn = NEXT_INSN (insn))
778 enum rtx_code code1 = GET_CODE (insn);
779 if (code1 == CALL_INSN)
780 INSN_VOLATILE (insn) = 1;
781 else if (code1 == INSN || code1 == JUMP_INSN)
783 /* Delete (in effect) any obvious no-op moves. */
784 if (GET_CODE (PATTERN (insn)) == SET
785 && GET_CODE (SET_DEST (PATTERN (insn))) == REG
786 && GET_CODE (SET_SRC (PATTERN (insn))) == REG
787 && REGNO (SET_DEST (PATTERN (insn))) ==
788 REGNO (SET_SRC (PATTERN (insn)))
789 /* Insns carrying these notes are useful later on. */
790 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
792 PUT_CODE (insn, NOTE);
793 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
794 NOTE_SOURCE_FILE (insn) = 0;
796 else if (GET_CODE (PATTERN (insn)) == PARALLEL)
798 /* If nothing but SETs of registers to themselves,
799 this insn can also be deleted. */
800 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
802 rtx tem = XVECEXP (PATTERN (insn), 0, i);
804 if (GET_CODE (tem) == USE
805 || GET_CODE (tem) == CLOBBER)
808 if (GET_CODE (tem) != SET
809 || GET_CODE (SET_DEST (tem)) != REG
810 || GET_CODE (SET_SRC (tem)) != REG
811 || REGNO (SET_DEST (tem)) != REGNO (SET_SRC (tem)))
815 if (i == XVECLEN (PATTERN (insn), 0)
816 /* Insns carrying these notes are useful later on. */
817 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
819 PUT_CODE (insn, NOTE);
820 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
821 NOTE_SOURCE_FILE (insn) = 0;
824 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
826 else if (GET_CODE (PATTERN (insn)) != USE)
827 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
828 /* A SET that makes space on the stack cannot be dead.
829 (Such SETs occur only for allocating variable-size data,
830 so they will always have a PLUS or MINUS according to the
831 direction of stack growth.)
832 Even if this function never uses this stack pointer value,
833 signal handlers do! */
834 else if (code1 == INSN && GET_CODE (PATTERN (insn)) == SET
835 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
836 #ifdef STACK_GROWS_DOWNWARD
837 && GET_CODE (SET_SRC (PATTERN (insn))) == MINUS
839 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
841 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx)
842 INSN_VOLATILE (insn) = 1;
846 if (n_basic_blocks > 0)
847 #ifdef EXIT_IGNORE_STACK
848 if (! EXIT_IGNORE_STACK
849 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
852 /* If exiting needs the right stack value,
853 consider the stack pointer live at the end of the function. */
854 basic_block_live_at_end[n_basic_blocks - 1]
855 [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
856 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
857 basic_block_new_live_at_end[n_basic_blocks - 1]
858 [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
859 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
862 /* Mark all global registers as being live at the end of the function
863 since they may be referenced by our caller. */
865 if (n_basic_blocks > 0)
866 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
869 basic_block_live_at_end[n_basic_blocks - 1]
870 [i / REGSET_ELT_BITS]
871 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
872 basic_block_new_live_at_end[n_basic_blocks - 1]
873 [i / REGSET_ELT_BITS]
874 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
877 /* Propagate life info through the basic blocks
878 around the graph of basic blocks.
880 This is a relaxation process: each time a new register
881 is live at the end of the basic block, we must scan the block
882 to determine which registers are, as a consequence, live at the beginning
883 of that block. These registers must then be marked live at the ends
884 of all the blocks that can transfer control to that block.
885 The process continues until it reaches a fixed point. */
892 for (i = n_basic_blocks - 1; i >= 0; i--)
894 int consider = first_pass;
895 int must_rescan = first_pass;
900 /* Set CONSIDER if this block needs thinking about at all
901 (that is, if the regs live now at the end of it
902 are not the same as were live at the end of it when
903 we last thought about it).
904 Set must_rescan if it needs to be thought about
905 instruction by instruction (that is, if any additional
906 reg that is live at the end now but was not live there before
907 is one of the significant regs of this basic block). */
909 for (j = 0; j < regset_size; j++)
911 register REGSET_ELT_TYPE x
912 = (basic_block_new_live_at_end[i][j]
913 & ~basic_block_live_at_end[i][j]);
916 if (x & basic_block_significant[i][j])
928 /* The live_at_start of this block may be changing,
929 so another pass will be required after this one. */
934 /* No complete rescan needed;
935 just record those variables newly known live at end
936 as live at start as well. */
937 for (j = 0; j < regset_size; j++)
939 register REGSET_ELT_TYPE x
940 = (basic_block_new_live_at_end[i][j]
941 & ~basic_block_live_at_end[i][j]);
942 basic_block_live_at_start[i][j] |= x;
943 basic_block_live_at_end[i][j] |= x;
948 /* Update the basic_block_live_at_start
949 by propagation backwards through the block. */
950 bcopy (basic_block_new_live_at_end[i],
951 basic_block_live_at_end[i], regset_bytes);
952 bcopy (basic_block_live_at_end[i],
953 basic_block_live_at_start[i], regset_bytes);
954 propagate_block (basic_block_live_at_start[i],
955 basic_block_head[i], basic_block_end[i], 0,
956 first_pass ? basic_block_significant[i]
962 register rtx jump, head;
963 /* Update the basic_block_new_live_at_end's of the block
964 that falls through into this one (if any). */
965 head = basic_block_head[i];
966 jump = PREV_INSN (head);
967 if (basic_block_drops_in[i])
969 register int from_block = BLOCK_NUM (jump);
971 for (j = 0; j < regset_size; j++)
972 basic_block_new_live_at_end[from_block][j]
973 |= basic_block_live_at_start[i][j];
975 /* Update the basic_block_new_live_at_end's of
976 all the blocks that jump to this one. */
977 if (GET_CODE (head) == CODE_LABEL)
978 for (jump = LABEL_REFS (head);
980 jump = LABEL_NEXTREF (jump))
982 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
984 for (j = 0; j < regset_size; j++)
985 basic_block_new_live_at_end[from_block][j]
986 |= basic_block_live_at_start[i][j];
996 /* The only pseudos that are live at the beginning of the function are
997 those that were not set anywhere in the function. local-alloc doesn't
998 know how to handle these correctly, so mark them as not local to any
1001 if (n_basic_blocks > 0)
1002 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
1003 if (basic_block_live_at_start[0][i / REGSET_ELT_BITS]
1004 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
1005 reg_basic_block[i] = REG_BLOCK_GLOBAL;
1007 /* Now the life information is accurate.
1008 Make one more pass over each basic block
1009 to delete dead stores, create autoincrement addressing
1010 and record how many times each register is used, is set, or dies.
1012 To save time, we operate directly in basic_block_live_at_end[i],
1013 thus destroying it (in fact, converting it into a copy of
1014 basic_block_live_at_start[i]). This is ok now because
1015 basic_block_live_at_end[i] is no longer used past this point. */
1019 for (i = 0; i < n_basic_blocks; i++)
1021 propagate_block (basic_block_live_at_end[i],
1022 basic_block_head[i], basic_block_end[i], 1,
1030 /* Something live during a setjmp should not be put in a register
1031 on certain machines which restore regs from stack frames
1032 rather than from the jmpbuf.
1033 But we don't need to do this for the user's variables, since
1034 ANSI says only volatile variables need this. */
1035 #ifdef LONGJMP_RESTORE_FROM_STACK
1036 for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1037 if (regs_live_at_setjmp[i / REGSET_ELT_BITS]
1038 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS))
1039 && regno_reg_rtx[i] != 0 && ! REG_USERVAR_P (regno_reg_rtx[i]))
1041 reg_live_length[i] = -1;
1042 reg_basic_block[i] = -1;
1047 /* We have a problem with any pseudoreg that
1048 lives across the setjmp. ANSI says that if a
1049 user variable does not change in value
1050 between the setjmp and the longjmp, then the longjmp preserves it.
1051 This includes longjmp from a place where the pseudo appears dead.
1052 (In principle, the value still exists if it is in scope.)
1053 If the pseudo goes in a hard reg, some other value may occupy
1054 that hard reg where this pseudo is dead, thus clobbering the pseudo.
1055 Conclusion: such a pseudo must not go in a hard reg. */
1056 for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1057 if ((regs_live_at_setjmp[i / REGSET_ELT_BITS]
1058 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
1059 && regno_reg_rtx[i] != 0)
1061 reg_live_length[i] = -1;
1062 reg_basic_block[i] = -1;
1065 obstack_free (&flow_obstack, NULL_PTR);
1068 /* Subroutines of life analysis. */
1070 /* Allocate the permanent data structures that represent the results
1071 of life analysis. Not static since used also for stupid life analysis. */
1074 allocate_for_life_analysis ()
1077 register regset tem;
1079 regset_size = ((max_regno + REGSET_ELT_BITS - 1) / REGSET_ELT_BITS);
1080 regset_bytes = regset_size * sizeof (*(regset)0);
1082 reg_n_refs = (int *) oballoc (max_regno * sizeof (int));
1083 bzero (reg_n_refs, max_regno * sizeof (int));
1085 reg_n_sets = (short *) oballoc (max_regno * sizeof (short));
1086 bzero (reg_n_sets, max_regno * sizeof (short));
1088 reg_n_deaths = (short *) oballoc (max_regno * sizeof (short));
1089 bzero (reg_n_deaths, max_regno * sizeof (short));
1091 reg_live_length = (int *) oballoc (max_regno * sizeof (int));
1092 bzero (reg_live_length, max_regno * sizeof (int));
1094 reg_n_calls_crossed = (int *) oballoc (max_regno * sizeof (int));
1095 bzero (reg_n_calls_crossed, max_regno * sizeof (int));
1097 reg_basic_block = (short *) oballoc (max_regno * sizeof (short));
1098 for (i = 0; i < max_regno; i++)
1099 reg_basic_block[i] = REG_BLOCK_UNKNOWN;
1101 basic_block_live_at_start = (regset *) oballoc (n_basic_blocks * sizeof (regset));
1102 tem = (regset) oballoc (n_basic_blocks * regset_bytes);
1103 bzero (tem, n_basic_blocks * regset_bytes);
1104 init_regset_vector (basic_block_live_at_start, tem, n_basic_blocks, regset_bytes);
1106 regs_live_at_setjmp = (regset) oballoc (regset_bytes);
1107 bzero (regs_live_at_setjmp, regset_bytes);
1110 /* Make each element of VECTOR point at a regset,
1111 taking the space for all those regsets from SPACE.
1112 SPACE is of type regset, but it is really as long as NELTS regsets.
1113 BYTES_PER_ELT is the number of bytes in one regset. */
1116 init_regset_vector (vector, space, nelts, bytes_per_elt)
1123 register regset p = space;
1125 for (i = 0; i < nelts; i++)
1128 p += bytes_per_elt / sizeof (*p);
1132 /* Compute the registers live at the beginning of a basic block
1133 from those live at the end.
1135 When called, OLD contains those live at the end.
1136 On return, it contains those live at the beginning.
1137 FIRST and LAST are the first and last insns of the basic block.
1139 FINAL is nonzero if we are doing the final pass which is not
1140 for computing the life info (since that has already been done)
1141 but for acting on it. On this pass, we delete dead stores,
1142 set up the logical links and dead-variables lists of instructions,
1143 and merge instructions for autoincrement and autodecrement addresses.
1145 SIGNIFICANT is nonzero only the first time for each basic block.
1146 If it is nonzero, it points to a regset in which we store
1147 a 1 for each register that is set within the block.
1149 BNUM is the number of the basic block. */
1152 propagate_block (old, first, last, final, significant, bnum)
1153 register regset old;
1165 /* The following variables are used only if FINAL is nonzero. */
1166 /* This vector gets one element for each reg that has been live
1167 at any point in the basic block that has been scanned so far.
1168 SOMETIMES_MAX says how many elements are in use so far.
1169 In each element, OFFSET is the byte-number within a regset
1170 for the register described by the element, and BIT is a mask
1171 for that register's bit within the byte. */
1172 register struct sometimes { short offset; short bit; } *regs_sometimes_live;
1173 int sometimes_max = 0;
1174 /* This regset has 1 for each reg that we have seen live so far.
1175 It and REGS_SOMETIMES_LIVE are updated together. */
1178 /* The loop depth may change in the middle of a basic block. Since we
1179 scan from end to beginning, we start with the depth at the end of the
1180 current basic block, and adjust as we pass ends and starts of loops. */
1181 loop_depth = basic_block_loop_depth[bnum];
1183 dead = (regset) alloca (regset_bytes);
1184 live = (regset) alloca (regset_bytes);
1189 /* Include any notes at the end of the block in the scan.
1190 This is in case the block ends with a call to setjmp. */
1192 while (NEXT_INSN (last) != 0 && GET_CODE (NEXT_INSN (last)) == NOTE)
1194 /* Look for loop boundaries, we are going forward here. */
1195 last = NEXT_INSN (last);
1196 if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_BEG)
1198 else if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_END)
1204 register int i, offset;
1205 REGSET_ELT_TYPE bit;
1208 maxlive = (regset) alloca (regset_bytes);
1209 bcopy (old, maxlive, regset_bytes);
1211 = (struct sometimes *) alloca (max_regno * sizeof (struct sometimes));
1213 /* Process the regs live at the end of the block.
1214 Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
1215 Also mark them as not local to any one basic block. */
1217 for (offset = 0, i = 0; offset < regset_size; offset++)
1218 for (bit = 1; bit; bit <<= 1, i++)
1222 if (old[offset] & bit)
1224 reg_basic_block[i] = REG_BLOCK_GLOBAL;
1225 regs_sometimes_live[sometimes_max].offset = offset;
1226 regs_sometimes_live[sometimes_max].bit = i % REGSET_ELT_BITS;
1232 /* Scan the block an insn at a time from end to beginning. */
1234 for (insn = last; ; insn = prev)
1236 prev = PREV_INSN (insn);
1238 /* Look for loop boundaries, remembering that we are going backwards. */
1239 if (GET_CODE (insn) == NOTE
1240 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1242 else if (GET_CODE (insn) == NOTE
1243 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1246 /* If we have LOOP_DEPTH == 0, there has been a bookkeeping error.
1247 Abort now rather than setting register status incorrectly. */
1248 if (loop_depth == 0)
1251 /* If this is a call to `setjmp' et al,
1252 warn if any non-volatile datum is live. */
1254 if (final && GET_CODE (insn) == NOTE
1255 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
1258 for (i = 0; i < regset_size; i++)
1259 regs_live_at_setjmp[i] |= old[i];
1262 /* Update the life-status of regs for this insn.
1263 First DEAD gets which regs are set in this insn
1264 then LIVE gets which regs are used in this insn.
1265 Then the regs live before the insn
1266 are those live after, with DEAD regs turned off,
1267 and then LIVE regs turned on. */
1269 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
1272 rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1274 = (insn_dead_p (PATTERN (insn), old, 0)
1275 /* Don't delete something that refers to volatile storage! */
1276 && ! INSN_VOLATILE (insn));
1278 = (insn_is_dead && note != 0
1279 && libcall_dead_p (PATTERN (insn), old, note, insn));
1281 /* If an instruction consists of just dead store(s) on final pass,
1282 "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
1283 We could really delete it with delete_insn, but that
1284 can cause trouble for first or last insn in a basic block. */
1285 if (final && insn_is_dead)
1287 PUT_CODE (insn, NOTE);
1288 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
1289 NOTE_SOURCE_FILE (insn) = 0;
1291 /* CC0 is now known to be dead. Either this insn used it,
1292 in which case it doesn't anymore, or clobbered it,
1293 so the next insn can't use it. */
1296 /* If this insn is copying the return value from a library call,
1297 delete the entire library call. */
1298 if (libcall_is_dead)
1300 rtx first = XEXP (note, 0);
1302 while (INSN_DELETED_P (first))
1303 first = NEXT_INSN (first);
1308 NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED;
1309 NOTE_SOURCE_FILE (p) = 0;
1315 for (i = 0; i < regset_size; i++)
1317 dead[i] = 0; /* Faster than bzero here */
1318 live[i] = 0; /* since regset_size is usually small */
1321 /* See if this is an increment or decrement that can be
1322 merged into a following memory address. */
1325 register rtx x = PATTERN (insn);
1326 /* Does this instruction increment or decrement a register? */
1327 if (final && GET_CODE (x) == SET
1328 && GET_CODE (SET_DEST (x)) == REG
1329 && (GET_CODE (SET_SRC (x)) == PLUS
1330 || GET_CODE (SET_SRC (x)) == MINUS)
1331 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1332 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1333 /* Ok, look for a following memory ref we can combine with.
1334 If one is found, change the memory ref to a PRE_INC
1335 or PRE_DEC, cancel this insn, and return 1.
1336 Return 0 if nothing has been done. */
1337 && try_pre_increment_1 (insn))
1340 #endif /* AUTO_INC_DEC */
1342 /* If this is not the final pass, and this insn is copying the
1343 value of a library call and it's dead, don't scan the
1344 insns that perform the library call, so that the call's
1345 arguments are not marked live. */
1346 if (libcall_is_dead)
1348 /* Mark the dest reg as `significant'. */
1349 mark_set_regs (old, dead, PATTERN (insn), NULL_RTX, significant);
1351 insn = XEXP (note, 0);
1352 prev = PREV_INSN (insn);
1354 else if (GET_CODE (PATTERN (insn)) == SET
1355 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1356 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1357 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1358 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1359 /* We have an insn to pop a constant amount off the stack.
1360 (Such insns use PLUS regardless of the direction of the stack,
1361 and any insn to adjust the stack by a constant is always a pop.)
1362 These insns, if not dead stores, have no effect on life. */
1366 /* LIVE gets the regs used in INSN;
1367 DEAD gets those set by it. Dead insns don't make anything
1370 mark_set_regs (old, dead, PATTERN (insn),
1371 final ? insn : NULL_RTX, significant);
1373 /* If an insn doesn't use CC0, it becomes dead since we
1374 assume that every insn clobbers it. So show it dead here;
1375 mark_used_regs will set it live if it is referenced. */
1379 mark_used_regs (old, live, PATTERN (insn), final, insn);
1381 /* Sometimes we may have inserted something before INSN (such as
1382 a move) when we make an auto-inc. So ensure we will scan
1385 prev = PREV_INSN (insn);
1388 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1392 /* Each call clobbers all call-clobbered regs that are not
1393 global. Note that the function-value reg is a
1394 call-clobbered reg, and mark_set_regs has already had
1395 a chance to handle it. */
1397 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1398 if (call_used_regs[i] && ! global_regs[i])
1399 dead[i / REGSET_ELT_BITS]
1400 |= ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS));
1402 /* The stack ptr is used (honorarily) by a CALL insn. */
1403 live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
1404 |= ((REGSET_ELT_TYPE) 1
1405 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS));
1407 /* Calls may also reference any of the global registers,
1408 so they are made live. */
1410 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1412 live[i / REGSET_ELT_BITS]
1413 |= ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS));
1415 /* Calls also clobber memory. */
1419 /* Update OLD for the registers used or set. */
1420 for (i = 0; i < regset_size; i++)
1426 if (GET_CODE (insn) == CALL_INSN && final)
1428 /* Any regs live at the time of a call instruction
1429 must not go in a register clobbered by calls.
1430 Find all regs now live and record this for them. */
1432 register struct sometimes *p = regs_sometimes_live;
1434 for (i = 0; i < sometimes_max; i++, p++)
1435 if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
1436 reg_n_calls_crossed[p->offset * REGSET_ELT_BITS + p->bit]+= 1;
1440 /* On final pass, add any additional sometimes-live regs
1441 into MAXLIVE and REGS_SOMETIMES_LIVE.
1442 Also update counts of how many insns each reg is live at. */
1446 for (i = 0; i < regset_size; i++)
1448 register REGSET_ELT_TYPE diff = live[i] & ~maxlive[i];
1454 for (regno = 0; diff && regno < REGSET_ELT_BITS; regno++)
1455 if (diff & ((REGSET_ELT_TYPE) 1 << regno))
1457 regs_sometimes_live[sometimes_max].offset = i;
1458 regs_sometimes_live[sometimes_max].bit = regno;
1459 diff &= ~ ((REGSET_ELT_TYPE) 1 << regno);
1466 register struct sometimes *p = regs_sometimes_live;
1467 for (i = 0; i < sometimes_max; i++, p++)
1469 if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
1470 reg_live_length[p->offset * REGSET_ELT_BITS + p->bit]++;
1480 if (num_scratch > max_scratch)
1481 max_scratch = num_scratch;
1484 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1485 (SET expressions whose destinations are registers dead after the insn).
1486 NEEDED is the regset that says which regs are alive after the insn.
1488 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */
1491 insn_dead_p (x, needed, call_ok)
1496 register RTX_CODE code = GET_CODE (x);
1497 /* If setting something that's a reg or part of one,
1498 see if that register's altered value will be live. */
1502 register rtx r = SET_DEST (x);
1503 /* A SET that is a subroutine call cannot be dead. */
1504 if (! call_ok && GET_CODE (SET_SRC (x)) == CALL)
1508 if (GET_CODE (r) == CC0)
1512 if (GET_CODE (r) == MEM && last_mem_set && ! MEM_VOLATILE_P (r)
1513 && rtx_equal_p (r, last_mem_set))
1516 while (GET_CODE (r) == SUBREG
1517 || GET_CODE (r) == STRICT_LOW_PART
1518 || GET_CODE (r) == ZERO_EXTRACT
1519 || GET_CODE (r) == SIGN_EXTRACT)
1522 if (GET_CODE (r) == REG)
1524 register int regno = REGNO (r);
1525 register int offset = regno / REGSET_ELT_BITS;
1526 register REGSET_ELT_TYPE bit
1527 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
1529 /* Don't delete insns to set global regs. */
1530 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
1531 /* Make sure insns to set frame pointer aren't deleted. */
1532 || regno == FRAME_POINTER_REGNUM
1533 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1534 /* Make sure insns to set arg pointer are never deleted
1535 (if the arg pointer isn't fixed, there will be a USE for
1536 it, so we can treat it normally). */
1537 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1539 || (needed[offset] & bit) != 0)
1542 /* If this is a hard register, verify that subsequent words are
1544 if (regno < FIRST_PSEUDO_REGISTER)
1546 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
1549 if ((needed[(regno + n) / REGSET_ELT_BITS]
1550 & ((REGSET_ELT_TYPE) 1
1551 << ((regno + n) % REGSET_ELT_BITS))) != 0)
1558 /* If performing several activities,
1559 insn is dead if each activity is individually dead.
1560 Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
1561 that's inside a PARALLEL doesn't make the insn worth keeping. */
1562 else if (code == PARALLEL)
1564 register int i = XVECLEN (x, 0);
1565 for (i--; i >= 0; i--)
1567 rtx elt = XVECEXP (x, 0, i);
1568 if (!insn_dead_p (elt, needed, call_ok)
1569 && GET_CODE (elt) != CLOBBER
1570 && GET_CODE (elt) != USE)
1575 /* We do not check CLOBBER or USE here.
1576 An insn consisting of just a CLOBBER or just a USE
1577 should not be deleted. */
1581 /* If X is the pattern of the last insn in a libcall, and assuming X is dead,
1582 return 1 if the entire library call is dead.
1583 This is true if X copies a register (hard or pseudo)
1584 and if the hard return reg of the call insn is dead.
1585 (The caller should have tested the destination of X already for death.)
1587 If this insn doesn't just copy a register, then we don't
1588 have an ordinary libcall. In that case, cse could not have
1589 managed to substitute the source for the dest later on,
1590 so we can assume the libcall is dead.
1592 NEEDED is the bit vector of pseudoregs live before this insn.
1593 NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
1596 libcall_dead_p (x, needed, note, insn)
1602 register RTX_CODE code = GET_CODE (x);
1606 register rtx r = SET_SRC (x);
1607 if (GET_CODE (r) == REG)
1609 rtx call = XEXP (note, 0);
1612 /* Find the call insn. */
1613 while (call != insn && GET_CODE (call) != CALL_INSN)
1614 call = NEXT_INSN (call);
1616 /* If there is none, do nothing special,
1617 since ordinary death handling can understand these insns. */
1621 /* See if the hard reg holding the value is dead.
1622 If this is a PARALLEL, find the call within it. */
1623 call = PATTERN (call);
1624 if (GET_CODE (call) == PARALLEL)
1626 for (i = XVECLEN (call, 0) - 1; i >= 0; i--)
1627 if (GET_CODE (XVECEXP (call, 0, i)) == SET
1628 && GET_CODE (SET_SRC (XVECEXP (call, 0, i))) == CALL)
1634 call = XVECEXP (call, 0, i);
1637 return insn_dead_p (call, needed, 1);
1643 /* Return 1 if register REGNO was used before it was set.
1644 In other words, if it is live at function entry.
1645 Don't count global regster variables, though. */
1648 regno_uninitialized (regno)
1651 if (n_basic_blocks == 0 || global_regs[regno])
1654 return (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1655 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS)));
1658 /* 1 if register REGNO was alive at a place where `setjmp' was called
1659 and was set more than once or is an argument.
1660 Such regs may be clobbered by `longjmp'. */
1663 regno_clobbered_at_setjmp (regno)
1666 if (n_basic_blocks == 0)
1669 return ((reg_n_sets[regno] > 1
1670 || (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1671 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))))
1672 && (regs_live_at_setjmp[regno / REGSET_ELT_BITS]
1673 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))));
1676 /* Process the registers that are set within X.
1677 Their bits are set to 1 in the regset DEAD,
1678 because they are dead prior to this insn.
1680 If INSN is nonzero, it is the insn being processed
1681 and the fact that it is nonzero implies this is the FINAL pass
1682 in propagate_block. In this case, various info about register
1683 usage is stored, LOG_LINKS fields of insns are set up. */
1685 static void mark_set_1 ();
1688 mark_set_regs (needed, dead, x, insn, significant)
1695 register RTX_CODE code = GET_CODE (x);
1697 if (code == SET || code == CLOBBER)
1698 mark_set_1 (needed, dead, x, insn, significant);
1699 else if (code == PARALLEL)
1702 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
1704 code = GET_CODE (XVECEXP (x, 0, i));
1705 if (code == SET || code == CLOBBER)
1706 mark_set_1 (needed, dead, XVECEXP (x, 0, i), insn, significant);
1711 /* Process a single SET rtx, X. */
1714 mark_set_1 (needed, dead, x, insn, significant)
1722 register rtx reg = SET_DEST (x);
1724 /* Modifying just one hardware register of a multi-reg value
1725 or just a byte field of a register
1726 does not mean the value from before this insn is now dead.
1727 But it does mean liveness of that register at the end of the block
1730 Within mark_set_1, however, we treat it as if the register is
1731 indeed modified. mark_used_regs will, however, also treat this
1732 register as being used. Thus, we treat these insns as setting a
1733 new value for the register as a function of its old value. This
1734 cases LOG_LINKS to be made appropriately and this will help combine. */
1736 while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
1737 || GET_CODE (reg) == SIGN_EXTRACT
1738 || GET_CODE (reg) == STRICT_LOW_PART)
1739 reg = XEXP (reg, 0);
1741 /* If we are writing into memory or into a register mentioned in the
1742 address of the last thing stored into memory, show we don't know
1743 what the last store was. If we are writing memory, save the address
1744 unless it is volatile. */
1745 if (GET_CODE (reg) == MEM
1746 || (GET_CODE (reg) == REG
1747 && last_mem_set != 0 && reg_overlap_mentioned_p (reg, last_mem_set)))
1750 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
1751 /* There are no REG_INC notes for SP, so we can't assume we'll see
1752 everything that invalidates it. To be safe, don't eliminate any
1753 stores though SP; none of them should be redundant anyway. */
1754 && ! reg_mentioned_p (stack_pointer_rtx, reg))
1757 if (GET_CODE (reg) == REG
1758 && (regno = REGNO (reg), regno != FRAME_POINTER_REGNUM)
1759 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1760 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1762 && ! (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
1763 /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
1765 register int offset = regno / REGSET_ELT_BITS;
1766 register REGSET_ELT_TYPE bit
1767 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
1768 REGSET_ELT_TYPE all_needed = (needed[offset] & bit);
1769 REGSET_ELT_TYPE some_needed = (needed[offset] & bit);
1771 /* Mark it as a significant register for this basic block. */
1773 significant[offset] |= bit;
1775 /* Mark it as as dead before this insn. */
1776 dead[offset] |= bit;
1778 /* A hard reg in a wide mode may really be multiple registers.
1779 If so, mark all of them just like the first. */
1780 if (regno < FIRST_PSEUDO_REGISTER)
1784 /* Nothing below is needed for the stack pointer; get out asap.
1785 Eg, log links aren't needed, since combine won't use them. */
1786 if (regno == STACK_POINTER_REGNUM)
1789 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
1793 significant[(regno + n) / REGSET_ELT_BITS]
1794 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
1795 dead[(regno + n) / REGSET_ELT_BITS]
1796 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
1798 |= (needed[(regno + n) / REGSET_ELT_BITS]
1799 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
1801 &= (needed[(regno + n) / REGSET_ELT_BITS]
1802 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
1805 /* Additional data to record if this is the final pass. */
1808 register rtx y = reg_next_use[regno];
1809 register int blocknum = BLOCK_NUM (insn);
1811 /* If this is a hard reg, record this function uses the reg. */
1813 if (regno < FIRST_PSEUDO_REGISTER)
1816 int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg));
1818 for (i = regno; i < endregno; i++)
1820 regs_ever_live[i] = 1;
1826 /* Keep track of which basic blocks each reg appears in. */
1828 if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
1829 reg_basic_block[regno] = blocknum;
1830 else if (reg_basic_block[regno] != blocknum)
1831 reg_basic_block[regno] = REG_BLOCK_GLOBAL;
1833 /* Count (weighted) references, stores, etc. This counts a
1834 register twice if it is modified, but that is correct. */
1835 reg_n_sets[regno]++;
1837 reg_n_refs[regno] += loop_depth;
1839 /* The insns where a reg is live are normally counted
1840 elsewhere, but we want the count to include the insn
1841 where the reg is set, and the normal counting mechanism
1842 would not count it. */
1843 reg_live_length[regno]++;
1846 /* The next use is no longer "next", since a store intervenes. */
1847 reg_next_use[regno] = 0;
1851 /* Make a logical link from the next following insn
1852 that uses this register, back to this insn.
1853 The following insns have already been processed.
1855 We don't build a LOG_LINK for hard registers containing
1856 in ASM_OPERANDs. If these registers get replaced,
1857 we might wind up changing the semantics of the insn,
1858 even if reload can make what appear to be valid assignments
1860 if (y && (BLOCK_NUM (y) == blocknum)
1861 && (regno >= FIRST_PSEUDO_REGISTER
1862 || asm_noperands (PATTERN (y)) < 0))
1864 = gen_rtx (INSN_LIST, VOIDmode, insn, LOG_LINKS (y));
1866 else if (! some_needed)
1868 /* Note that dead stores have already been deleted when possible
1869 If we get here, we have found a dead store that cannot
1870 be eliminated (because the same insn does something useful).
1871 Indicate this by marking the reg being set as dying here. */
1873 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
1874 reg_n_deaths[REGNO (reg)]++;
1878 /* This is a case where we have a multi-word hard register
1879 and some, but not all, of the words of the register are
1880 needed in subsequent insns. Write REG_UNUSED notes
1881 for those parts that were not needed. This case should
1886 for (i = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1;
1888 if ((needed[(regno + i) / REGSET_ELT_BITS]
1889 & ((REGSET_ELT_TYPE) 1
1890 << ((regno + i) % REGSET_ELT_BITS))) == 0)
1892 = gen_rtx (EXPR_LIST, REG_UNUSED,
1893 gen_rtx (REG, word_mode, regno + i),
1899 /* If this is the last pass and this is a SCRATCH, show it will be dying
1900 here and count it. */
1901 else if (GET_CODE (reg) == SCRATCH && insn != 0)
1904 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
1911 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
1915 find_auto_inc (needed, x, insn)
1920 rtx addr = XEXP (x, 0);
1923 /* Here we detect use of an index register which might be good for
1924 postincrement, postdecrement, preincrement, or predecrement. */
1926 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
1927 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
1929 if (GET_CODE (addr) == REG)
1932 register int size = GET_MODE_SIZE (GET_MODE (x));
1935 int regno = REGNO (addr);
1937 /* Is the next use an increment that might make auto-increment? */
1938 incr = reg_next_use[regno];
1939 if (incr && GET_CODE (PATTERN (incr)) == SET
1940 && BLOCK_NUM (incr) == BLOCK_NUM (insn)
1941 /* Can't add side effects to jumps; if reg is spilled and
1942 reloaded, there's no way to store back the altered value. */
1943 && GET_CODE (insn) != JUMP_INSN
1944 && (y = SET_SRC (PATTERN (incr)), GET_CODE (y) == PLUS)
1945 && XEXP (y, 0) == addr
1946 && GET_CODE (XEXP (y, 1)) == CONST_INT
1948 #ifdef HAVE_POST_INCREMENT
1949 || (INTVAL (XEXP (y, 1)) == size && offset == 0)
1951 #ifdef HAVE_POST_DECREMENT
1952 || (INTVAL (XEXP (y, 1)) == - size && offset == 0)
1954 #ifdef HAVE_PRE_INCREMENT
1955 || (INTVAL (XEXP (y, 1)) == size && offset == size)
1957 #ifdef HAVE_PRE_DECREMENT
1958 || (INTVAL (XEXP (y, 1)) == - size && offset == - size)
1961 /* Make sure this reg appears only once in this insn. */
1962 && (use = find_use_as_address (PATTERN (insn), addr, offset),
1963 use != 0 && use != (rtx) 1))
1966 rtx q = SET_DEST (PATTERN (incr));
1968 if (dead_or_set_p (incr, addr))
1970 else if (GET_CODE (q) == REG && ! reg_used_between_p (q, insn, incr))
1972 /* We have *p followed by q = p+size.
1973 Both p and q must be live afterward,
1974 and q must be dead before.
1975 Change it to q = p, ...*q..., q = q+size.
1976 Then fall into the usual case. */
1980 emit_move_insn (q, addr);
1981 insns = get_insns ();
1984 /* If anything in INSNS have UID's that don't fit within the
1985 extra space we allocate earlier, we can't make this auto-inc.
1986 This should never happen. */
1987 for (temp = insns; temp; temp = NEXT_INSN (temp))
1989 if (INSN_UID (temp) > max_uid_for_flow)
1991 BLOCK_NUM (temp) = BLOCK_NUM (insn);
1994 emit_insns_before (insns, insn);
1996 if (basic_block_head[BLOCK_NUM (insn)] == insn)
1997 basic_block_head[BLOCK_NUM (insn)] = insns;
2002 /* INCR will become a NOTE and INSN won't contain a
2003 use of ADDR. If a use of ADDR was just placed in
2004 the insn before INSN, make that the next use.
2005 Otherwise, invalidate it. */
2006 if (GET_CODE (PREV_INSN (insn)) == INSN
2007 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
2008 && SET_SRC (PATTERN (PREV_INSN (insn))) == addr)
2009 reg_next_use[regno] = PREV_INSN (insn);
2011 reg_next_use[regno] = 0;
2017 /* REGNO is now used in INCR which is below INSN, but
2018 it previously wasn't live here. If we don't mark
2019 it as needed, we'll put a REG_DEAD note for it
2020 on this insn, which is incorrect. */
2021 needed[regno / REGSET_ELT_BITS]
2022 |= (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2024 /* If there are any calls between INSN and INCR, show
2025 that REGNO now crosses them. */
2026 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
2027 if (GET_CODE (temp) == CALL_INSN)
2028 reg_n_calls_crossed[regno]++;
2033 /* We have found a suitable auto-increment: do POST_INC around
2034 the register here, and patch out the increment instruction
2036 XEXP (x, 0) = gen_rtx ((INTVAL (XEXP (y, 1)) == size
2037 ? (offset ? PRE_INC : POST_INC)
2038 : (offset ? PRE_DEC : POST_DEC)),
2041 /* Record that this insn has an implicit side effect. */
2043 = gen_rtx (EXPR_LIST, REG_INC, addr, REG_NOTES (insn));
2045 /* Modify the old increment-insn to simply copy
2046 the already-incremented value of our register. */
2047 SET_SRC (PATTERN (incr)) = addr;
2048 /* Indicate insn must be re-recognized. */
2049 INSN_CODE (incr) = -1;
2051 /* If that makes it a no-op (copying the register into itself)
2052 then delete it so it won't appear to be a "use" and a "set"
2053 of this register. */
2054 if (SET_DEST (PATTERN (incr)) == addr)
2056 PUT_CODE (incr, NOTE);
2057 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
2058 NOTE_SOURCE_FILE (incr) = 0;
2061 if (regno >= FIRST_PSEUDO_REGISTER)
2063 /* Count an extra reference to the reg. When a reg is
2064 incremented, spilling it is worse, so we want to make
2065 that less likely. */
2066 reg_n_refs[regno] += loop_depth;
2067 /* Count the increment as a setting of the register,
2068 even though it isn't a SET in rtl. */
2069 reg_n_sets[regno]++;
2075 #endif /* AUTO_INC_DEC */
2077 /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
2078 This is done assuming the registers needed from X
2079 are those that have 1-bits in NEEDED.
2081 On the final pass, FINAL is 1. This means try for autoincrement
2082 and count the uses and deaths of each pseudo-reg.
2084 INSN is the containing instruction. If INSN is dead, this function is not
2088 mark_used_regs (needed, live, x, final, insn)
2095 register RTX_CODE code;
2100 code = GET_CODE (x);
2122 /* Invalidate the data for the last MEM stored. We could do this only
2123 if the addresses conflict, but this doesn't seem worthwhile. */
2128 find_auto_inc (needed, x, insn);
2133 /* See a register other than being set
2134 => mark it as needed. */
2138 register int offset = regno / REGSET_ELT_BITS;
2139 register REGSET_ELT_TYPE bit
2140 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2141 int all_needed = (needed[offset] & bit) != 0;
2142 int some_needed = (needed[offset] & bit) != 0;
2144 live[offset] |= bit;
2145 /* A hard reg in a wide mode may really be multiple registers.
2146 If so, mark all of them just like the first. */
2147 if (regno < FIRST_PSEUDO_REGISTER)
2151 /* For stack ptr or fixed arg pointer,
2152 nothing below can be necessary, so waste no more time. */
2153 if (regno == STACK_POINTER_REGNUM
2154 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2155 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2157 || regno == FRAME_POINTER_REGNUM)
2159 /* If this is a register we are going to try to eliminate,
2160 don't mark it live here. If we are successful in
2161 eliminating it, it need not be live unless it is used for
2162 pseudos, in which case it will have been set live when
2163 it was allocated to the pseudos. If the register will not
2164 be eliminated, reload will set it live at that point. */
2166 if (! TEST_HARD_REG_BIT (elim_reg_set, regno))
2167 regs_ever_live[regno] = 1;
2170 /* No death notes for global register variables;
2171 their values are live after this function exits. */
2172 if (global_regs[regno])
2175 reg_next_use[regno] = insn;
2179 n = HARD_REGNO_NREGS (regno, GET_MODE (x));
2182 live[(regno + n) / REGSET_ELT_BITS]
2183 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
2185 |= (needed[(regno + n) / REGSET_ELT_BITS]
2186 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2188 &= (needed[(regno + n) / REGSET_ELT_BITS]
2189 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2194 /* Record where each reg is used, so when the reg
2195 is set we know the next insn that uses it. */
2197 reg_next_use[regno] = insn;
2199 if (regno < FIRST_PSEUDO_REGISTER)
2201 /* If a hard reg is being used,
2202 record that this function does use it. */
2204 i = HARD_REGNO_NREGS (regno, GET_MODE (x));
2208 regs_ever_live[regno + --i] = 1;
2213 /* Keep track of which basic block each reg appears in. */
2215 register int blocknum = BLOCK_NUM (insn);
2217 if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
2218 reg_basic_block[regno] = blocknum;
2219 else if (reg_basic_block[regno] != blocknum)
2220 reg_basic_block[regno] = REG_BLOCK_GLOBAL;
2222 /* Count (weighted) number of uses of each reg. */
2224 reg_n_refs[regno] += loop_depth;
2227 /* Record and count the insns in which a reg dies.
2228 If it is used in this insn and was dead below the insn
2229 then it dies in this insn. If it was set in this insn,
2230 we do not make a REG_DEAD note; likewise if we already
2231 made such a note. */
2234 && ! dead_or_set_p (insn, x)
2236 && (regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
2240 /* If none of the words in X is needed, make a REG_DEAD
2241 note. Otherwise, we must make partial REG_DEAD notes. */
2245 = gen_rtx (EXPR_LIST, REG_DEAD, x, REG_NOTES (insn));
2246 reg_n_deaths[regno]++;
2252 /* Don't make a REG_DEAD note for a part of a register
2253 that is set in the insn. */
2255 for (i = HARD_REGNO_NREGS (regno, GET_MODE (x)) - 1;
2257 if ((needed[(regno + i) / REGSET_ELT_BITS]
2258 & ((REGSET_ELT_TYPE) 1
2259 << ((regno + i) % REGSET_ELT_BITS))) == 0
2260 && ! dead_or_set_regno_p (insn, regno + i))
2262 = gen_rtx (EXPR_LIST, REG_DEAD,
2263 gen_rtx (REG, word_mode, regno + i),
2273 register rtx testreg = SET_DEST (x);
2276 /* If storing into MEM, don't show it as being used. But do
2277 show the address as being used. */
2278 if (GET_CODE (testreg) == MEM)
2282 find_auto_inc (needed, testreg, insn);
2284 mark_used_regs (needed, live, XEXP (testreg, 0), final, insn);
2285 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2289 /* Storing in STRICT_LOW_PART is like storing in a reg
2290 in that this SET might be dead, so ignore it in TESTREG.
2291 but in some other ways it is like using the reg.
2293 Storing in a SUBREG or a bit field is like storing the entire
2294 register in that if the register's value is not used
2295 then this SET is not needed. */
2296 while (GET_CODE (testreg) == STRICT_LOW_PART
2297 || GET_CODE (testreg) == ZERO_EXTRACT
2298 || GET_CODE (testreg) == SIGN_EXTRACT
2299 || GET_CODE (testreg) == SUBREG)
2301 /* Modifying a single register in an alternate mode
2302 does not use any of the old value. But these other
2303 ways of storing in a register do use the old value. */
2304 if (GET_CODE (testreg) == SUBREG
2305 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
2310 testreg = XEXP (testreg, 0);
2313 /* If this is a store into a register,
2314 recursively scan the value being stored. */
2316 if (GET_CODE (testreg) == REG
2317 && (regno = REGNO (testreg), regno != FRAME_POINTER_REGNUM)
2318 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2319 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2322 /* We used to exclude global_regs here, but that seems wrong.
2323 Storing in them is like storing in mem. */
2325 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2327 mark_used_regs (needed, live, SET_DEST (x), final, insn);
2334 /* If exiting needs the right stack value, consider this insn as
2335 using the stack pointer. In any event, consider it as using
2336 all global registers. */
2338 #ifdef EXIT_IGNORE_STACK
2339 if (! EXIT_IGNORE_STACK
2340 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
2342 live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
2343 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
2345 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2347 live[i / REGSET_ELT_BITS]
2348 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
2352 /* Recursively scan the operands of this expression. */
2355 register char *fmt = GET_RTX_FORMAT (code);
2358 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2362 /* Tail recursive case: save a function call level. */
2368 mark_used_regs (needed, live, XEXP (x, i), final, insn);
2370 else if (fmt[i] == 'E')
2373 for (j = 0; j < XVECLEN (x, i); j++)
2374 mark_used_regs (needed, live, XVECEXP (x, i, j), final, insn);
2383 try_pre_increment_1 (insn)
2386 /* Find the next use of this reg. If in same basic block,
2387 make it do pre-increment or pre-decrement if appropriate. */
2388 rtx x = PATTERN (insn);
2389 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
2390 * INTVAL (XEXP (SET_SRC (x), 1)));
2391 int regno = REGNO (SET_DEST (x));
2392 rtx y = reg_next_use[regno];
2394 && BLOCK_NUM (y) == BLOCK_NUM (insn)
2395 && try_pre_increment (y, SET_DEST (PATTERN (insn)),
2398 /* We have found a suitable auto-increment
2399 and already changed insn Y to do it.
2400 So flush this increment-instruction. */
2401 PUT_CODE (insn, NOTE);
2402 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
2403 NOTE_SOURCE_FILE (insn) = 0;
2404 /* Count a reference to this reg for the increment
2405 insn we are deleting. When a reg is incremented.
2406 spilling it is worse, so we want to make that
2408 if (regno >= FIRST_PSEUDO_REGISTER)
2410 reg_n_refs[regno] += loop_depth;
2411 reg_n_sets[regno]++;
2418 /* Try to change INSN so that it does pre-increment or pre-decrement
2419 addressing on register REG in order to add AMOUNT to REG.
2420 AMOUNT is negative for pre-decrement.
2421 Returns 1 if the change could be made.
2422 This checks all about the validity of the result of modifying INSN. */
2425 try_pre_increment (insn, reg, amount)
2427 HOST_WIDE_INT amount;
2431 /* Nonzero if we can try to make a pre-increment or pre-decrement.
2432 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
2434 /* Nonzero if we can try to make a post-increment or post-decrement.
2435 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
2436 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
2437 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
2440 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
2443 /* From the sign of increment, see which possibilities are conceivable
2444 on this target machine. */
2445 #ifdef HAVE_PRE_INCREMENT
2449 #ifdef HAVE_POST_INCREMENT
2454 #ifdef HAVE_PRE_DECREMENT
2458 #ifdef HAVE_POST_DECREMENT
2463 if (! (pre_ok || post_ok))
2466 /* It is not safe to add a side effect to a jump insn
2467 because if the incremented register is spilled and must be reloaded
2468 there would be no way to store the incremented value back in memory. */
2470 if (GET_CODE (insn) == JUMP_INSN)
2475 use = find_use_as_address (PATTERN (insn), reg, 0);
2476 if (post_ok && (use == 0 || use == (rtx) 1))
2478 use = find_use_as_address (PATTERN (insn), reg, -amount);
2482 if (use == 0 || use == (rtx) 1)
2485 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
2488 XEXP (use, 0) = gen_rtx (amount > 0
2489 ? (do_post ? POST_INC : PRE_INC)
2490 : (do_post ? POST_DEC : PRE_DEC),
2493 /* Record that this insn now has an implicit side effect on X. */
2494 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_INC, reg, REG_NOTES (insn));
2498 #endif /* AUTO_INC_DEC */
2500 /* Find the place in the rtx X where REG is used as a memory address.
2501 Return the MEM rtx that so uses it.
2502 If PLUSCONST is nonzero, search instead for a memory address equivalent to
2503 (plus REG (const_int PLUSCONST)).
2505 If such an address does not appear, return 0.
2506 If REG appears more than once, or is used other than in such an address,
2510 find_use_as_address (x, reg, plusconst)
2515 enum rtx_code code = GET_CODE (x);
2516 char *fmt = GET_RTX_FORMAT (code);
2518 register rtx value = 0;
2521 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
2524 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
2525 && XEXP (XEXP (x, 0), 0) == reg
2526 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
2527 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
2530 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
2532 /* If REG occurs inside a MEM used in a bit-field reference,
2533 that is unacceptable. */
2534 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
2535 return (rtx) (HOST_WIDE_INT) 1;
2539 return (rtx) (HOST_WIDE_INT) 1;
2541 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2545 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
2549 return (rtx) (HOST_WIDE_INT) 1;
2554 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
2556 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
2560 return (rtx) (HOST_WIDE_INT) 1;
2568 /* Write information about registers and basic blocks into FILE.
2569 This is part of making a debugging dump. */
2572 dump_flow_info (file)
2576 static char *reg_class_names[] = REG_CLASS_NAMES;
2578 fprintf (file, "%d registers.\n", max_regno);
2580 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
2583 enum reg_class class, altclass;
2584 fprintf (file, "\nRegister %d used %d times across %d insns",
2585 i, reg_n_refs[i], reg_live_length[i]);
2586 if (reg_basic_block[i] >= 0)
2587 fprintf (file, " in block %d", reg_basic_block[i]);
2588 if (reg_n_deaths[i] != 1)
2589 fprintf (file, "; dies in %d places", reg_n_deaths[i]);
2590 if (reg_n_calls_crossed[i] == 1)
2591 fprintf (file, "; crosses 1 call");
2592 else if (reg_n_calls_crossed[i])
2593 fprintf (file, "; crosses %d calls", reg_n_calls_crossed[i]);
2594 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
2595 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
2596 class = reg_preferred_class (i);
2597 altclass = reg_alternate_class (i);
2598 if (class != GENERAL_REGS || altclass != ALL_REGS)
2600 if (altclass == ALL_REGS || class == ALL_REGS)
2601 fprintf (file, "; pref %s", reg_class_names[(int) class]);
2602 else if (altclass == NO_REGS)
2603 fprintf (file, "; %s or none", reg_class_names[(int) class]);
2605 fprintf (file, "; pref %s, else %s",
2606 reg_class_names[(int) class],
2607 reg_class_names[(int) altclass]);
2609 if (REGNO_POINTER_FLAG (i))
2610 fprintf (file, "; pointer");
2611 fprintf (file, ".\n");
2613 fprintf (file, "\n%d basic blocks.\n", n_basic_blocks);
2614 for (i = 0; i < n_basic_blocks; i++)
2616 register rtx head, jump;
2618 fprintf (file, "\nBasic block %d: first insn %d, last %d.\n",
2620 INSN_UID (basic_block_head[i]),
2621 INSN_UID (basic_block_end[i]));
2622 /* The control flow graph's storage is freed
2623 now when flow_analysis returns.
2624 Don't try to print it if it is gone. */
2625 if (basic_block_drops_in)
2627 fprintf (file, "Reached from blocks: ");
2628 head = basic_block_head[i];
2629 if (GET_CODE (head) == CODE_LABEL)
2630 for (jump = LABEL_REFS (head);
2632 jump = LABEL_NEXTREF (jump))
2634 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
2635 fprintf (file, " %d", from_block);
2637 if (basic_block_drops_in[i])
2638 fprintf (file, " previous");
2640 fprintf (file, "\nRegisters live at start:");
2641 for (regno = 0; regno < max_regno; regno++)
2643 register int offset = regno / REGSET_ELT_BITS;
2644 register REGSET_ELT_TYPE bit
2645 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2646 if (basic_block_live_at_start[i][offset] & bit)
2647 fprintf (file, " %d", regno);
2649 fprintf (file, "\n");
2651 fprintf (file, "\n");