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.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 (in this function)
480 that are referenced by non-jump instructions. */
483 for (x = label_value_list; x; x = XEXP (x, 1))
484 if (! LABEL_REF_NONLOCAL_P (x))
485 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
488 /* Record which basic blocks control can drop in to. */
492 for (i = 0; i < n_basic_blocks; i++)
494 register rtx insn = PREV_INSN (basic_block_head[i]);
495 /* TEMP1 is used to avoid a bug in Sequent's compiler. */
497 while (insn && GET_CODE (insn) == NOTE)
498 insn = PREV_INSN (insn);
499 temp1 = insn && GET_CODE (insn) != BARRIER;
500 basic_block_drops_in[i] = temp1;
504 /* Now find which basic blocks can actually be reached
505 and put all jump insns' LABEL_REFS onto the ref-chains
506 of their target labels. */
508 if (n_basic_blocks > 0)
510 int something_marked = 1;
512 /* Find all indirect jump insns and mark them as possibly jumping
513 to all the labels whose addresses are explicitly used.
514 This is because, when there are computed gotos,
515 we can't tell which labels they jump to, of all the possibilities. */
517 for (insn = f; insn; insn = NEXT_INSN (insn))
518 if (GET_CODE (insn) == JUMP_INSN
519 && GET_CODE (PATTERN (insn)) == SET
520 && SET_DEST (PATTERN (insn)) == pc_rtx
521 && (GET_CODE (SET_SRC (PATTERN (insn))) == REG
522 || GET_CODE (SET_SRC (PATTERN (insn))) == MEM))
525 for (x = label_value_list; x; x = XEXP (x, 1))
526 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
528 for (x = forced_labels; x; x = XEXP (x, 1))
529 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
533 /* Find all call insns and mark them as possibly jumping
534 to all the nonlocal goto handler labels. */
536 for (insn = f; insn; insn = NEXT_INSN (insn))
537 if (GET_CODE (insn) == CALL_INSN)
540 for (x = nonlocal_label_list; x; x = XEXP (x, 1))
541 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
543 /* ??? This could be made smarter:
544 in some cases it's possible to tell that certain
545 calls will not do a nonlocal goto.
547 For example, if the nested functions that do the
548 nonlocal gotos do not have their addresses taken, then
549 only calls to those functions or to other nested
550 functions that use them could possibly do nonlocal
554 /* Pass over all blocks, marking each block that is reachable
555 and has not yet been marked.
556 Keep doing this until, in one pass, no blocks have been marked.
557 Then blocks_live and blocks_marked are identical and correct.
558 In addition, all jumps actually reachable have been marked. */
560 while (something_marked)
562 something_marked = 0;
563 for (i = 0; i < n_basic_blocks; i++)
564 if (block_live[i] && !block_marked[i])
567 something_marked = 1;
568 if (i + 1 < n_basic_blocks && basic_block_drops_in[i + 1])
569 block_live[i + 1] = 1;
570 insn = basic_block_end[i];
571 if (GET_CODE (insn) == JUMP_INSN)
572 mark_label_ref (PATTERN (insn), insn, 0);
576 /* Now delete the code for any basic blocks that can't be reached.
577 They can occur because jump_optimize does not recognize
578 unreachable loops as unreachable. */
580 for (i = 0; i < n_basic_blocks; i++)
583 insn = basic_block_head[i];
586 if (GET_CODE (insn) == BARRIER)
588 if (GET_CODE (insn) != NOTE)
590 PUT_CODE (insn, NOTE);
591 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
592 NOTE_SOURCE_FILE (insn) = 0;
594 if (insn == basic_block_end[i])
596 /* BARRIERs are between basic blocks, not part of one.
597 Delete a BARRIER if the preceding jump is deleted.
598 We cannot alter a BARRIER into a NOTE
599 because it is too short; but we can really delete
600 it because it is not part of a basic block. */
601 if (NEXT_INSN (insn) != 0
602 && GET_CODE (NEXT_INSN (insn)) == BARRIER)
603 delete_insn (NEXT_INSN (insn));
606 insn = NEXT_INSN (insn);
608 /* Each time we delete some basic blocks,
609 see if there is a jump around them that is
610 being turned into a no-op. If so, delete it. */
612 if (block_live[i - 1])
615 for (j = i; j < n_basic_blocks; j++)
619 insn = basic_block_end[i - 1];
620 if (GET_CODE (insn) == JUMP_INSN
621 /* An unconditional jump is the only possibility
622 we must check for, since a conditional one
623 would make these blocks live. */
624 && simplejump_p (insn)
625 && (label = XEXP (SET_SRC (PATTERN (insn)), 0), 1)
626 && INSN_UID (label) != 0
627 && BLOCK_NUM (label) == j)
629 PUT_CODE (insn, NOTE);
630 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
631 NOTE_SOURCE_FILE (insn) = 0;
632 if (GET_CODE (NEXT_INSN (insn)) != BARRIER)
634 delete_insn (NEXT_INSN (insn));
643 /* Check expression X for label references;
644 if one is found, add INSN to the label's chain of references.
646 CHECKDUP means check for and avoid creating duplicate references
647 from the same insn. Such duplicates do no serious harm but
648 can slow life analysis. CHECKDUP is set only when duplicates
652 mark_label_ref (x, insn, checkdup)
656 register RTX_CODE code;
660 /* We can be called with NULL when scanning label_value_list. */
665 if (code == LABEL_REF)
667 register rtx label = XEXP (x, 0);
669 if (GET_CODE (label) != CODE_LABEL)
671 /* If the label was never emitted, this insn is junk,
672 but avoid a crash trying to refer to BLOCK_NUM (label).
673 This can happen as a result of a syntax error
674 and a diagnostic has already been printed. */
675 if (INSN_UID (label) == 0)
677 CONTAINING_INSN (x) = insn;
678 /* if CHECKDUP is set, check for duplicate ref from same insn
681 for (y = LABEL_REFS (label); y != label; y = LABEL_NEXTREF (y))
682 if (CONTAINING_INSN (y) == insn)
684 LABEL_NEXTREF (x) = LABEL_REFS (label);
685 LABEL_REFS (label) = x;
686 block_live_static[BLOCK_NUM (label)] = 1;
690 fmt = GET_RTX_FORMAT (code);
691 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
694 mark_label_ref (XEXP (x, i), insn, 0);
698 for (j = 0; j < XVECLEN (x, i); j++)
699 mark_label_ref (XVECEXP (x, i, j), insn, 1);
704 /* Determine which registers are live at the start of each
705 basic block of the function whose first insn is F.
706 NREGS is the number of registers used in F.
707 We allocate the vector basic_block_live_at_start
708 and the regsets that it points to, and fill them with the data.
709 regset_size and regset_bytes are also set here. */
712 life_analysis (f, nregs)
719 /* For each basic block, a bitmask of regs
720 live on exit from the block. */
721 regset *basic_block_live_at_end;
722 /* For each basic block, a bitmask of regs
723 live on entry to a successor-block of this block.
724 If this does not match basic_block_live_at_end,
725 that must be updated, and the block must be rescanned. */
726 regset *basic_block_new_live_at_end;
727 /* For each basic block, a bitmask of regs
728 whose liveness at the end of the basic block
729 can make a difference in which regs are live on entry to the block.
730 These are the regs that are set within the basic block,
731 possibly excluding those that are used after they are set. */
732 regset *basic_block_significant;
736 struct obstack flow_obstack;
738 gcc_obstack_init (&flow_obstack);
742 bzero (regs_ever_live, sizeof regs_ever_live);
744 /* Allocate and zero out many data structures
745 that will record the data from lifetime analysis. */
747 allocate_for_life_analysis ();
749 reg_next_use = (rtx *) alloca (nregs * sizeof (rtx));
750 bzero (reg_next_use, nregs * sizeof (rtx));
752 /* Set up several regset-vectors used internally within this function.
753 Their meanings are documented above, with their declarations. */
755 basic_block_live_at_end = (regset *) alloca (n_basic_blocks * sizeof (regset));
756 /* Don't use alloca since that leads to a crash rather than an error message
757 if there isn't enough space.
758 Don't use oballoc since we may need to allocate other things during
759 this function on the temporary obstack. */
760 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
761 bzero (tem, n_basic_blocks * regset_bytes);
762 init_regset_vector (basic_block_live_at_end, tem, n_basic_blocks, regset_bytes);
764 basic_block_new_live_at_end = (regset *) alloca (n_basic_blocks * sizeof (regset));
765 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
766 bzero (tem, n_basic_blocks * regset_bytes);
767 init_regset_vector (basic_block_new_live_at_end, tem, n_basic_blocks, regset_bytes);
769 basic_block_significant = (regset *) alloca (n_basic_blocks * sizeof (regset));
770 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
771 bzero (tem, n_basic_blocks * regset_bytes);
772 init_regset_vector (basic_block_significant, tem, n_basic_blocks, regset_bytes);
774 /* Record which insns refer to any volatile memory
775 or for any reason can't be deleted just because they are dead stores.
776 Also, delete any insns that copy a register to itself. */
778 for (insn = f; insn; insn = NEXT_INSN (insn))
780 enum rtx_code code1 = GET_CODE (insn);
781 if (code1 == CALL_INSN)
782 INSN_VOLATILE (insn) = 1;
783 else if (code1 == INSN || code1 == JUMP_INSN)
785 /* Delete (in effect) any obvious no-op moves. */
786 if (GET_CODE (PATTERN (insn)) == SET
787 && GET_CODE (SET_DEST (PATTERN (insn))) == REG
788 && GET_CODE (SET_SRC (PATTERN (insn))) == REG
789 && REGNO (SET_DEST (PATTERN (insn))) ==
790 REGNO (SET_SRC (PATTERN (insn)))
791 /* Insns carrying these notes are useful later on. */
792 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
794 PUT_CODE (insn, NOTE);
795 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
796 NOTE_SOURCE_FILE (insn) = 0;
798 else if (GET_CODE (PATTERN (insn)) == PARALLEL)
800 /* If nothing but SETs of registers to themselves,
801 this insn can also be deleted. */
802 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
804 rtx tem = XVECEXP (PATTERN (insn), 0, i);
806 if (GET_CODE (tem) == USE
807 || GET_CODE (tem) == CLOBBER)
810 if (GET_CODE (tem) != SET
811 || GET_CODE (SET_DEST (tem)) != REG
812 || GET_CODE (SET_SRC (tem)) != REG
813 || REGNO (SET_DEST (tem)) != REGNO (SET_SRC (tem)))
817 if (i == XVECLEN (PATTERN (insn), 0)
818 /* Insns carrying these notes are useful later on. */
819 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
821 PUT_CODE (insn, NOTE);
822 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
823 NOTE_SOURCE_FILE (insn) = 0;
826 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
828 else if (GET_CODE (PATTERN (insn)) != USE)
829 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
830 /* A SET that makes space on the stack cannot be dead.
831 (Such SETs occur only for allocating variable-size data,
832 so they will always have a PLUS or MINUS according to the
833 direction of stack growth.)
834 Even if this function never uses this stack pointer value,
835 signal handlers do! */
836 else if (code1 == INSN && GET_CODE (PATTERN (insn)) == SET
837 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
838 #ifdef STACK_GROWS_DOWNWARD
839 && GET_CODE (SET_SRC (PATTERN (insn))) == MINUS
841 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
843 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx)
844 INSN_VOLATILE (insn) = 1;
848 if (n_basic_blocks > 0)
849 #ifdef EXIT_IGNORE_STACK
850 if (! EXIT_IGNORE_STACK
851 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
854 /* If exiting needs the right stack value,
855 consider the stack pointer live at the end of the function. */
856 basic_block_live_at_end[n_basic_blocks - 1]
857 [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
858 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
859 basic_block_new_live_at_end[n_basic_blocks - 1]
860 [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
861 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
864 /* Mark the frame pointer is needed at the end of the function. If
865 we end up eliminating it, it will be removed from the live list
866 of each basic block by reload. */
868 if (n_basic_blocks > 0)
870 basic_block_live_at_end[n_basic_blocks - 1]
871 [FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
872 |= (REGSET_ELT_TYPE) 1 << (FRAME_POINTER_REGNUM % REGSET_ELT_BITS);
873 basic_block_new_live_at_end[n_basic_blocks - 1]
874 [FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
875 |= (REGSET_ELT_TYPE) 1 << (FRAME_POINTER_REGNUM % REGSET_ELT_BITS);
878 /* Mark all global registers as being live at the end of the function
879 since they may be referenced by our caller. */
881 if (n_basic_blocks > 0)
882 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
885 basic_block_live_at_end[n_basic_blocks - 1]
886 [i / REGSET_ELT_BITS]
887 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
888 basic_block_new_live_at_end[n_basic_blocks - 1]
889 [i / REGSET_ELT_BITS]
890 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
893 /* Propagate life info through the basic blocks
894 around the graph of basic blocks.
896 This is a relaxation process: each time a new register
897 is live at the end of the basic block, we must scan the block
898 to determine which registers are, as a consequence, live at the beginning
899 of that block. These registers must then be marked live at the ends
900 of all the blocks that can transfer control to that block.
901 The process continues until it reaches a fixed point. */
908 for (i = n_basic_blocks - 1; i >= 0; i--)
910 int consider = first_pass;
911 int must_rescan = first_pass;
916 /* Set CONSIDER if this block needs thinking about at all
917 (that is, if the regs live now at the end of it
918 are not the same as were live at the end of it when
919 we last thought about it).
920 Set must_rescan if it needs to be thought about
921 instruction by instruction (that is, if any additional
922 reg that is live at the end now but was not live there before
923 is one of the significant regs of this basic block). */
925 for (j = 0; j < regset_size; j++)
927 register REGSET_ELT_TYPE x
928 = (basic_block_new_live_at_end[i][j]
929 & ~basic_block_live_at_end[i][j]);
932 if (x & basic_block_significant[i][j])
944 /* The live_at_start of this block may be changing,
945 so another pass will be required after this one. */
950 /* No complete rescan needed;
951 just record those variables newly known live at end
952 as live at start as well. */
953 for (j = 0; j < regset_size; j++)
955 register REGSET_ELT_TYPE x
956 = (basic_block_new_live_at_end[i][j]
957 & ~basic_block_live_at_end[i][j]);
958 basic_block_live_at_start[i][j] |= x;
959 basic_block_live_at_end[i][j] |= x;
964 /* Update the basic_block_live_at_start
965 by propagation backwards through the block. */
966 bcopy (basic_block_new_live_at_end[i],
967 basic_block_live_at_end[i], regset_bytes);
968 bcopy (basic_block_live_at_end[i],
969 basic_block_live_at_start[i], regset_bytes);
970 propagate_block (basic_block_live_at_start[i],
971 basic_block_head[i], basic_block_end[i], 0,
972 first_pass ? basic_block_significant[i]
978 register rtx jump, head;
979 /* Update the basic_block_new_live_at_end's of the block
980 that falls through into this one (if any). */
981 head = basic_block_head[i];
982 jump = PREV_INSN (head);
983 if (basic_block_drops_in[i])
985 register int from_block = BLOCK_NUM (jump);
987 for (j = 0; j < regset_size; j++)
988 basic_block_new_live_at_end[from_block][j]
989 |= basic_block_live_at_start[i][j];
991 /* Update the basic_block_new_live_at_end's of
992 all the blocks that jump to this one. */
993 if (GET_CODE (head) == CODE_LABEL)
994 for (jump = LABEL_REFS (head);
996 jump = LABEL_NEXTREF (jump))
998 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
1000 for (j = 0; j < regset_size; j++)
1001 basic_block_new_live_at_end[from_block][j]
1002 |= basic_block_live_at_start[i][j];
1012 /* The only pseudos that are live at the beginning of the function are
1013 those that were not set anywhere in the function. local-alloc doesn't
1014 know how to handle these correctly, so mark them as not local to any
1017 if (n_basic_blocks > 0)
1018 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
1019 if (basic_block_live_at_start[0][i / REGSET_ELT_BITS]
1020 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
1021 reg_basic_block[i] = REG_BLOCK_GLOBAL;
1023 /* Now the life information is accurate.
1024 Make one more pass over each basic block
1025 to delete dead stores, create autoincrement addressing
1026 and record how many times each register is used, is set, or dies.
1028 To save time, we operate directly in basic_block_live_at_end[i],
1029 thus destroying it (in fact, converting it into a copy of
1030 basic_block_live_at_start[i]). This is ok now because
1031 basic_block_live_at_end[i] is no longer used past this point. */
1035 for (i = 0; i < n_basic_blocks; i++)
1037 propagate_block (basic_block_live_at_end[i],
1038 basic_block_head[i], basic_block_end[i], 1,
1046 /* Something live during a setjmp should not be put in a register
1047 on certain machines which restore regs from stack frames
1048 rather than from the jmpbuf.
1049 But we don't need to do this for the user's variables, since
1050 ANSI says only volatile variables need this. */
1051 #ifdef LONGJMP_RESTORE_FROM_STACK
1052 for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1053 if (regs_live_at_setjmp[i / REGSET_ELT_BITS]
1054 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS))
1055 && regno_reg_rtx[i] != 0 && ! REG_USERVAR_P (regno_reg_rtx[i]))
1057 reg_live_length[i] = -1;
1058 reg_basic_block[i] = -1;
1063 /* We have a problem with any pseudoreg that
1064 lives across the setjmp. ANSI says that if a
1065 user variable does not change in value
1066 between the setjmp and the longjmp, then the longjmp preserves it.
1067 This includes longjmp from a place where the pseudo appears dead.
1068 (In principle, the value still exists if it is in scope.)
1069 If the pseudo goes in a hard reg, some other value may occupy
1070 that hard reg where this pseudo is dead, thus clobbering the pseudo.
1071 Conclusion: such a pseudo must not go in a hard reg. */
1072 for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1073 if ((regs_live_at_setjmp[i / REGSET_ELT_BITS]
1074 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
1075 && regno_reg_rtx[i] != 0)
1077 reg_live_length[i] = -1;
1078 reg_basic_block[i] = -1;
1081 obstack_free (&flow_obstack, NULL_PTR);
1084 /* Subroutines of life analysis. */
1086 /* Allocate the permanent data structures that represent the results
1087 of life analysis. Not static since used also for stupid life analysis. */
1090 allocate_for_life_analysis ()
1093 register regset tem;
1095 regset_size = ((max_regno + REGSET_ELT_BITS - 1) / REGSET_ELT_BITS);
1096 regset_bytes = regset_size * sizeof (*(regset)0);
1098 reg_n_refs = (int *) oballoc (max_regno * sizeof (int));
1099 bzero (reg_n_refs, max_regno * sizeof (int));
1101 reg_n_sets = (short *) oballoc (max_regno * sizeof (short));
1102 bzero (reg_n_sets, max_regno * sizeof (short));
1104 reg_n_deaths = (short *) oballoc (max_regno * sizeof (short));
1105 bzero (reg_n_deaths, max_regno * sizeof (short));
1107 reg_live_length = (int *) oballoc (max_regno * sizeof (int));
1108 bzero (reg_live_length, max_regno * sizeof (int));
1110 reg_n_calls_crossed = (int *) oballoc (max_regno * sizeof (int));
1111 bzero (reg_n_calls_crossed, max_regno * sizeof (int));
1113 reg_basic_block = (short *) oballoc (max_regno * sizeof (short));
1114 for (i = 0; i < max_regno; i++)
1115 reg_basic_block[i] = REG_BLOCK_UNKNOWN;
1117 basic_block_live_at_start = (regset *) oballoc (n_basic_blocks * sizeof (regset));
1118 tem = (regset) oballoc (n_basic_blocks * regset_bytes);
1119 bzero (tem, n_basic_blocks * regset_bytes);
1120 init_regset_vector (basic_block_live_at_start, tem, n_basic_blocks, regset_bytes);
1122 regs_live_at_setjmp = (regset) oballoc (regset_bytes);
1123 bzero (regs_live_at_setjmp, regset_bytes);
1126 /* Make each element of VECTOR point at a regset,
1127 taking the space for all those regsets from SPACE.
1128 SPACE is of type regset, but it is really as long as NELTS regsets.
1129 BYTES_PER_ELT is the number of bytes in one regset. */
1132 init_regset_vector (vector, space, nelts, bytes_per_elt)
1139 register regset p = space;
1141 for (i = 0; i < nelts; i++)
1144 p += bytes_per_elt / sizeof (*p);
1148 /* Compute the registers live at the beginning of a basic block
1149 from those live at the end.
1151 When called, OLD contains those live at the end.
1152 On return, it contains those live at the beginning.
1153 FIRST and LAST are the first and last insns of the basic block.
1155 FINAL is nonzero if we are doing the final pass which is not
1156 for computing the life info (since that has already been done)
1157 but for acting on it. On this pass, we delete dead stores,
1158 set up the logical links and dead-variables lists of instructions,
1159 and merge instructions for autoincrement and autodecrement addresses.
1161 SIGNIFICANT is nonzero only the first time for each basic block.
1162 If it is nonzero, it points to a regset in which we store
1163 a 1 for each register that is set within the block.
1165 BNUM is the number of the basic block. */
1168 propagate_block (old, first, last, final, significant, bnum)
1169 register regset old;
1181 /* The following variables are used only if FINAL is nonzero. */
1182 /* This vector gets one element for each reg that has been live
1183 at any point in the basic block that has been scanned so far.
1184 SOMETIMES_MAX says how many elements are in use so far.
1185 In each element, OFFSET is the byte-number within a regset
1186 for the register described by the element, and BIT is a mask
1187 for that register's bit within the byte. */
1188 register struct sometimes { short offset; short bit; } *regs_sometimes_live;
1189 int sometimes_max = 0;
1190 /* This regset has 1 for each reg that we have seen live so far.
1191 It and REGS_SOMETIMES_LIVE are updated together. */
1194 /* The loop depth may change in the middle of a basic block. Since we
1195 scan from end to beginning, we start with the depth at the end of the
1196 current basic block, and adjust as we pass ends and starts of loops. */
1197 loop_depth = basic_block_loop_depth[bnum];
1199 dead = (regset) alloca (regset_bytes);
1200 live = (regset) alloca (regset_bytes);
1205 /* Include any notes at the end of the block in the scan.
1206 This is in case the block ends with a call to setjmp. */
1208 while (NEXT_INSN (last) != 0 && GET_CODE (NEXT_INSN (last)) == NOTE)
1210 /* Look for loop boundaries, we are going forward here. */
1211 last = NEXT_INSN (last);
1212 if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_BEG)
1214 else if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_END)
1220 register int i, offset;
1221 REGSET_ELT_TYPE bit;
1224 maxlive = (regset) alloca (regset_bytes);
1225 bcopy (old, maxlive, regset_bytes);
1227 = (struct sometimes *) alloca (max_regno * sizeof (struct sometimes));
1229 /* Process the regs live at the end of the block.
1230 Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
1231 Also mark them as not local to any one basic block. */
1233 for (offset = 0, i = 0; offset < regset_size; offset++)
1234 for (bit = 1; bit; bit <<= 1, i++)
1238 if (old[offset] & bit)
1240 reg_basic_block[i] = REG_BLOCK_GLOBAL;
1241 regs_sometimes_live[sometimes_max].offset = offset;
1242 regs_sometimes_live[sometimes_max].bit = i % REGSET_ELT_BITS;
1248 /* Scan the block an insn at a time from end to beginning. */
1250 for (insn = last; ; insn = prev)
1252 prev = PREV_INSN (insn);
1254 /* Look for loop boundaries, remembering that we are going backwards. */
1255 if (GET_CODE (insn) == NOTE
1256 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1258 else if (GET_CODE (insn) == NOTE
1259 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1262 /* If we have LOOP_DEPTH == 0, there has been a bookkeeping error.
1263 Abort now rather than setting register status incorrectly. */
1264 if (loop_depth == 0)
1267 /* If this is a call to `setjmp' et al,
1268 warn if any non-volatile datum is live. */
1270 if (final && GET_CODE (insn) == NOTE
1271 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
1274 for (i = 0; i < regset_size; i++)
1275 regs_live_at_setjmp[i] |= old[i];
1278 /* Update the life-status of regs for this insn.
1279 First DEAD gets which regs are set in this insn
1280 then LIVE gets which regs are used in this insn.
1281 Then the regs live before the insn
1282 are those live after, with DEAD regs turned off,
1283 and then LIVE regs turned on. */
1285 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
1288 rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1290 = (insn_dead_p (PATTERN (insn), old, 0)
1291 /* Don't delete something that refers to volatile storage! */
1292 && ! INSN_VOLATILE (insn));
1294 = (insn_is_dead && note != 0
1295 && libcall_dead_p (PATTERN (insn), old, note, insn));
1297 /* If an instruction consists of just dead store(s) on final pass,
1298 "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
1299 We could really delete it with delete_insn, but that
1300 can cause trouble for first or last insn in a basic block. */
1301 if (final && insn_is_dead)
1303 PUT_CODE (insn, NOTE);
1304 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
1305 NOTE_SOURCE_FILE (insn) = 0;
1307 /* CC0 is now known to be dead. Either this insn used it,
1308 in which case it doesn't anymore, or clobbered it,
1309 so the next insn can't use it. */
1312 /* If this insn is copying the return value from a library call,
1313 delete the entire library call. */
1314 if (libcall_is_dead)
1316 rtx first = XEXP (note, 0);
1318 while (INSN_DELETED_P (first))
1319 first = NEXT_INSN (first);
1324 NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED;
1325 NOTE_SOURCE_FILE (p) = 0;
1331 for (i = 0; i < regset_size; i++)
1333 dead[i] = 0; /* Faster than bzero here */
1334 live[i] = 0; /* since regset_size is usually small */
1337 /* See if this is an increment or decrement that can be
1338 merged into a following memory address. */
1341 register rtx x = PATTERN (insn);
1342 /* Does this instruction increment or decrement a register? */
1343 if (final && GET_CODE (x) == SET
1344 && GET_CODE (SET_DEST (x)) == REG
1345 && (GET_CODE (SET_SRC (x)) == PLUS
1346 || GET_CODE (SET_SRC (x)) == MINUS)
1347 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1348 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1349 /* Ok, look for a following memory ref we can combine with.
1350 If one is found, change the memory ref to a PRE_INC
1351 or PRE_DEC, cancel this insn, and return 1.
1352 Return 0 if nothing has been done. */
1353 && try_pre_increment_1 (insn))
1356 #endif /* AUTO_INC_DEC */
1358 /* If this is not the final pass, and this insn is copying the
1359 value of a library call and it's dead, don't scan the
1360 insns that perform the library call, so that the call's
1361 arguments are not marked live. */
1362 if (libcall_is_dead)
1364 /* Mark the dest reg as `significant'. */
1365 mark_set_regs (old, dead, PATTERN (insn), NULL_RTX, significant);
1367 insn = XEXP (note, 0);
1368 prev = PREV_INSN (insn);
1370 else if (GET_CODE (PATTERN (insn)) == SET
1371 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1372 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1373 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1374 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1375 /* We have an insn to pop a constant amount off the stack.
1376 (Such insns use PLUS regardless of the direction of the stack,
1377 and any insn to adjust the stack by a constant is always a pop.)
1378 These insns, if not dead stores, have no effect on life. */
1382 /* LIVE gets the regs used in INSN;
1383 DEAD gets those set by it. Dead insns don't make anything
1386 mark_set_regs (old, dead, PATTERN (insn),
1387 final ? insn : NULL_RTX, significant);
1389 /* If an insn doesn't use CC0, it becomes dead since we
1390 assume that every insn clobbers it. So show it dead here;
1391 mark_used_regs will set it live if it is referenced. */
1395 mark_used_regs (old, live, PATTERN (insn), final, insn);
1397 /* Sometimes we may have inserted something before INSN (such as
1398 a move) when we make an auto-inc. So ensure we will scan
1401 prev = PREV_INSN (insn);
1404 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1408 /* Each call clobbers all call-clobbered regs that are not
1409 global. Note that the function-value reg is a
1410 call-clobbered reg, and mark_set_regs has already had
1411 a chance to handle it. */
1413 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1414 if (call_used_regs[i] && ! global_regs[i])
1415 dead[i / REGSET_ELT_BITS]
1416 |= ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS));
1418 /* The stack ptr is used (honorarily) by a CALL insn. */
1419 live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
1420 |= ((REGSET_ELT_TYPE) 1
1421 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS));
1423 /* Calls may also reference any of the global registers,
1424 so they are made live. */
1426 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1428 live[i / REGSET_ELT_BITS]
1429 |= ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS));
1431 /* Calls also clobber memory. */
1435 /* Update OLD for the registers used or set. */
1436 for (i = 0; i < regset_size; i++)
1442 if (GET_CODE (insn) == CALL_INSN && final)
1444 /* Any regs live at the time of a call instruction
1445 must not go in a register clobbered by calls.
1446 Find all regs now live and record this for them. */
1448 register struct sometimes *p = regs_sometimes_live;
1450 for (i = 0; i < sometimes_max; i++, p++)
1451 if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
1452 reg_n_calls_crossed[p->offset * REGSET_ELT_BITS + p->bit]+= 1;
1456 /* On final pass, add any additional sometimes-live regs
1457 into MAXLIVE and REGS_SOMETIMES_LIVE.
1458 Also update counts of how many insns each reg is live at. */
1462 for (i = 0; i < regset_size; i++)
1464 register REGSET_ELT_TYPE diff = live[i] & ~maxlive[i];
1470 for (regno = 0; diff && regno < REGSET_ELT_BITS; regno++)
1471 if (diff & ((REGSET_ELT_TYPE) 1 << regno))
1473 regs_sometimes_live[sometimes_max].offset = i;
1474 regs_sometimes_live[sometimes_max].bit = regno;
1475 diff &= ~ ((REGSET_ELT_TYPE) 1 << regno);
1482 register struct sometimes *p = regs_sometimes_live;
1483 for (i = 0; i < sometimes_max; i++, p++)
1485 if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
1486 reg_live_length[p->offset * REGSET_ELT_BITS + p->bit]++;
1496 if (num_scratch > max_scratch)
1497 max_scratch = num_scratch;
1500 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1501 (SET expressions whose destinations are registers dead after the insn).
1502 NEEDED is the regset that says which regs are alive after the insn.
1504 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */
1507 insn_dead_p (x, needed, call_ok)
1512 register RTX_CODE code = GET_CODE (x);
1513 /* If setting something that's a reg or part of one,
1514 see if that register's altered value will be live. */
1518 register rtx r = SET_DEST (x);
1519 /* A SET that is a subroutine call cannot be dead. */
1520 if (! call_ok && GET_CODE (SET_SRC (x)) == CALL)
1524 if (GET_CODE (r) == CC0)
1528 if (GET_CODE (r) == MEM && last_mem_set && ! MEM_VOLATILE_P (r)
1529 && rtx_equal_p (r, last_mem_set))
1532 while (GET_CODE (r) == SUBREG
1533 || GET_CODE (r) == STRICT_LOW_PART
1534 || GET_CODE (r) == ZERO_EXTRACT
1535 || GET_CODE (r) == SIGN_EXTRACT)
1538 if (GET_CODE (r) == REG)
1540 register int regno = REGNO (r);
1541 register int offset = regno / REGSET_ELT_BITS;
1542 register REGSET_ELT_TYPE bit
1543 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
1545 /* Don't delete insns to set global regs. */
1546 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
1547 /* Make sure insns to set frame pointer aren't deleted. */
1548 || regno == FRAME_POINTER_REGNUM
1549 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1550 /* Make sure insns to set arg pointer are never deleted
1551 (if the arg pointer isn't fixed, there will be a USE for
1552 it, so we can treat it normally). */
1553 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1555 || (needed[offset] & bit) != 0)
1558 /* If this is a hard register, verify that subsequent words are
1560 if (regno < FIRST_PSEUDO_REGISTER)
1562 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
1565 if ((needed[(regno + n) / REGSET_ELT_BITS]
1566 & ((REGSET_ELT_TYPE) 1
1567 << ((regno + n) % REGSET_ELT_BITS))) != 0)
1574 /* If performing several activities,
1575 insn is dead if each activity is individually dead.
1576 Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
1577 that's inside a PARALLEL doesn't make the insn worth keeping. */
1578 else if (code == PARALLEL)
1580 register int i = XVECLEN (x, 0);
1581 for (i--; i >= 0; i--)
1583 rtx elt = XVECEXP (x, 0, i);
1584 if (!insn_dead_p (elt, needed, call_ok)
1585 && GET_CODE (elt) != CLOBBER
1586 && GET_CODE (elt) != USE)
1591 /* We do not check CLOBBER or USE here.
1592 An insn consisting of just a CLOBBER or just a USE
1593 should not be deleted. */
1597 /* If X is the pattern of the last insn in a libcall, and assuming X is dead,
1598 return 1 if the entire library call is dead.
1599 This is true if X copies a register (hard or pseudo)
1600 and if the hard return reg of the call insn is dead.
1601 (The caller should have tested the destination of X already for death.)
1603 If this insn doesn't just copy a register, then we don't
1604 have an ordinary libcall. In that case, cse could not have
1605 managed to substitute the source for the dest later on,
1606 so we can assume the libcall is dead.
1608 NEEDED is the bit vector of pseudoregs live before this insn.
1609 NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
1612 libcall_dead_p (x, needed, note, insn)
1618 register RTX_CODE code = GET_CODE (x);
1622 register rtx r = SET_SRC (x);
1623 if (GET_CODE (r) == REG)
1625 rtx call = XEXP (note, 0);
1628 /* Find the call insn. */
1629 while (call != insn && GET_CODE (call) != CALL_INSN)
1630 call = NEXT_INSN (call);
1632 /* If there is none, do nothing special,
1633 since ordinary death handling can understand these insns. */
1637 /* See if the hard reg holding the value is dead.
1638 If this is a PARALLEL, find the call within it. */
1639 call = PATTERN (call);
1640 if (GET_CODE (call) == PARALLEL)
1642 for (i = XVECLEN (call, 0) - 1; i >= 0; i--)
1643 if (GET_CODE (XVECEXP (call, 0, i)) == SET
1644 && GET_CODE (SET_SRC (XVECEXP (call, 0, i))) == CALL)
1650 call = XVECEXP (call, 0, i);
1653 return insn_dead_p (call, needed, 1);
1659 /* Return 1 if register REGNO was used before it was set.
1660 In other words, if it is live at function entry.
1661 Don't count global regster variables, though. */
1664 regno_uninitialized (regno)
1667 if (n_basic_blocks == 0 || global_regs[regno])
1670 return (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1671 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS)));
1674 /* 1 if register REGNO was alive at a place where `setjmp' was called
1675 and was set more than once or is an argument.
1676 Such regs may be clobbered by `longjmp'. */
1679 regno_clobbered_at_setjmp (regno)
1682 if (n_basic_blocks == 0)
1685 return ((reg_n_sets[regno] > 1
1686 || (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1687 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))))
1688 && (regs_live_at_setjmp[regno / REGSET_ELT_BITS]
1689 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))));
1692 /* Process the registers that are set within X.
1693 Their bits are set to 1 in the regset DEAD,
1694 because they are dead prior to this insn.
1696 If INSN is nonzero, it is the insn being processed
1697 and the fact that it is nonzero implies this is the FINAL pass
1698 in propagate_block. In this case, various info about register
1699 usage is stored, LOG_LINKS fields of insns are set up. */
1701 static void mark_set_1 ();
1704 mark_set_regs (needed, dead, x, insn, significant)
1711 register RTX_CODE code = GET_CODE (x);
1713 if (code == SET || code == CLOBBER)
1714 mark_set_1 (needed, dead, x, insn, significant);
1715 else if (code == PARALLEL)
1718 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
1720 code = GET_CODE (XVECEXP (x, 0, i));
1721 if (code == SET || code == CLOBBER)
1722 mark_set_1 (needed, dead, XVECEXP (x, 0, i), insn, significant);
1727 /* Process a single SET rtx, X. */
1730 mark_set_1 (needed, dead, x, insn, significant)
1738 register rtx reg = SET_DEST (x);
1740 /* Modifying just one hardware register of a multi-reg value
1741 or just a byte field of a register
1742 does not mean the value from before this insn is now dead.
1743 But it does mean liveness of that register at the end of the block
1746 Within mark_set_1, however, we treat it as if the register is
1747 indeed modified. mark_used_regs will, however, also treat this
1748 register as being used. Thus, we treat these insns as setting a
1749 new value for the register as a function of its old value. This
1750 cases LOG_LINKS to be made appropriately and this will help combine. */
1752 while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
1753 || GET_CODE (reg) == SIGN_EXTRACT
1754 || GET_CODE (reg) == STRICT_LOW_PART)
1755 reg = XEXP (reg, 0);
1757 /* If we are writing into memory or into a register mentioned in the
1758 address of the last thing stored into memory, show we don't know
1759 what the last store was. If we are writing memory, save the address
1760 unless it is volatile. */
1761 if (GET_CODE (reg) == MEM
1762 || (GET_CODE (reg) == REG
1763 && last_mem_set != 0 && reg_overlap_mentioned_p (reg, last_mem_set)))
1766 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
1767 /* There are no REG_INC notes for SP, so we can't assume we'll see
1768 everything that invalidates it. To be safe, don't eliminate any
1769 stores though SP; none of them should be redundant anyway. */
1770 && ! reg_mentioned_p (stack_pointer_rtx, reg))
1773 if (GET_CODE (reg) == REG
1774 && (regno = REGNO (reg), regno != FRAME_POINTER_REGNUM)
1775 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1776 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1778 && ! (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
1779 /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
1781 register int offset = regno / REGSET_ELT_BITS;
1782 register REGSET_ELT_TYPE bit
1783 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
1784 REGSET_ELT_TYPE all_needed = (needed[offset] & bit);
1785 REGSET_ELT_TYPE some_needed = (needed[offset] & bit);
1787 /* Mark it as a significant register for this basic block. */
1789 significant[offset] |= bit;
1791 /* Mark it as as dead before this insn. */
1792 dead[offset] |= bit;
1794 /* A hard reg in a wide mode may really be multiple registers.
1795 If so, mark all of them just like the first. */
1796 if (regno < FIRST_PSEUDO_REGISTER)
1800 /* Nothing below is needed for the stack pointer; get out asap.
1801 Eg, log links aren't needed, since combine won't use them. */
1802 if (regno == STACK_POINTER_REGNUM)
1805 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
1809 significant[(regno + n) / REGSET_ELT_BITS]
1810 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
1811 dead[(regno + n) / REGSET_ELT_BITS]
1812 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
1814 |= (needed[(regno + n) / REGSET_ELT_BITS]
1815 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
1817 &= (needed[(regno + n) / REGSET_ELT_BITS]
1818 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
1821 /* Additional data to record if this is the final pass. */
1824 register rtx y = reg_next_use[regno];
1825 register int blocknum = BLOCK_NUM (insn);
1827 /* If this is a hard reg, record this function uses the reg. */
1829 if (regno < FIRST_PSEUDO_REGISTER)
1832 int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg));
1834 for (i = regno; i < endregno; i++)
1836 regs_ever_live[i] = 1;
1842 /* Keep track of which basic blocks each reg appears in. */
1844 if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
1845 reg_basic_block[regno] = blocknum;
1846 else if (reg_basic_block[regno] != blocknum)
1847 reg_basic_block[regno] = REG_BLOCK_GLOBAL;
1849 /* Count (weighted) references, stores, etc. This counts a
1850 register twice if it is modified, but that is correct. */
1851 reg_n_sets[regno]++;
1853 reg_n_refs[regno] += loop_depth;
1855 /* The insns where a reg is live are normally counted
1856 elsewhere, but we want the count to include the insn
1857 where the reg is set, and the normal counting mechanism
1858 would not count it. */
1859 reg_live_length[regno]++;
1862 /* The next use is no longer "next", since a store intervenes. */
1863 reg_next_use[regno] = 0;
1867 /* Make a logical link from the next following insn
1868 that uses this register, back to this insn.
1869 The following insns have already been processed.
1871 We don't build a LOG_LINK for hard registers containing
1872 in ASM_OPERANDs. If these registers get replaced,
1873 we might wind up changing the semantics of the insn,
1874 even if reload can make what appear to be valid assignments
1876 if (y && (BLOCK_NUM (y) == blocknum)
1877 && (regno >= FIRST_PSEUDO_REGISTER
1878 || asm_noperands (PATTERN (y)) < 0))
1880 = gen_rtx (INSN_LIST, VOIDmode, insn, LOG_LINKS (y));
1882 else if (! some_needed)
1884 /* Note that dead stores have already been deleted when possible
1885 If we get here, we have found a dead store that cannot
1886 be eliminated (because the same insn does something useful).
1887 Indicate this by marking the reg being set as dying here. */
1889 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
1890 reg_n_deaths[REGNO (reg)]++;
1894 /* This is a case where we have a multi-word hard register
1895 and some, but not all, of the words of the register are
1896 needed in subsequent insns. Write REG_UNUSED notes
1897 for those parts that were not needed. This case should
1902 for (i = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1;
1904 if ((needed[(regno + i) / REGSET_ELT_BITS]
1905 & ((REGSET_ELT_TYPE) 1
1906 << ((regno + i) % REGSET_ELT_BITS))) == 0)
1908 = gen_rtx (EXPR_LIST, REG_UNUSED,
1909 gen_rtx (REG, word_mode, regno + i),
1915 /* If this is the last pass and this is a SCRATCH, show it will be dying
1916 here and count it. */
1917 else if (GET_CODE (reg) == SCRATCH && insn != 0)
1920 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
1927 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
1931 find_auto_inc (needed, x, insn)
1936 rtx addr = XEXP (x, 0);
1939 /* Here we detect use of an index register which might be good for
1940 postincrement, postdecrement, preincrement, or predecrement. */
1942 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
1943 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
1945 if (GET_CODE (addr) == REG)
1948 register int size = GET_MODE_SIZE (GET_MODE (x));
1951 int regno = REGNO (addr);
1953 /* Is the next use an increment that might make auto-increment? */
1954 incr = reg_next_use[regno];
1955 if (incr && GET_CODE (PATTERN (incr)) == SET
1956 && BLOCK_NUM (incr) == BLOCK_NUM (insn)
1957 /* Can't add side effects to jumps; if reg is spilled and
1958 reloaded, there's no way to store back the altered value. */
1959 && GET_CODE (insn) != JUMP_INSN
1960 && (y = SET_SRC (PATTERN (incr)), GET_CODE (y) == PLUS)
1961 && XEXP (y, 0) == addr
1962 && GET_CODE (XEXP (y, 1)) == CONST_INT
1964 #ifdef HAVE_POST_INCREMENT
1965 || (INTVAL (XEXP (y, 1)) == size && offset == 0)
1967 #ifdef HAVE_POST_DECREMENT
1968 || (INTVAL (XEXP (y, 1)) == - size && offset == 0)
1970 #ifdef HAVE_PRE_INCREMENT
1971 || (INTVAL (XEXP (y, 1)) == size && offset == size)
1973 #ifdef HAVE_PRE_DECREMENT
1974 || (INTVAL (XEXP (y, 1)) == - size && offset == - size)
1977 /* Make sure this reg appears only once in this insn. */
1978 && (use = find_use_as_address (PATTERN (insn), addr, offset),
1979 use != 0 && use != (rtx) 1))
1982 rtx q = SET_DEST (PATTERN (incr));
1984 if (dead_or_set_p (incr, addr))
1986 else if (GET_CODE (q) == REG && ! reg_used_between_p (q, insn, incr))
1988 /* We have *p followed by q = p+size.
1989 Both p and q must be live afterward,
1990 and q must be dead before.
1991 Change it to q = p, ...*q..., q = q+size.
1992 Then fall into the usual case. */
1996 emit_move_insn (q, addr);
1997 insns = get_insns ();
2000 /* If anything in INSNS have UID's that don't fit within the
2001 extra space we allocate earlier, we can't make this auto-inc.
2002 This should never happen. */
2003 for (temp = insns; temp; temp = NEXT_INSN (temp))
2005 if (INSN_UID (temp) > max_uid_for_flow)
2007 BLOCK_NUM (temp) = BLOCK_NUM (insn);
2010 emit_insns_before (insns, insn);
2012 if (basic_block_head[BLOCK_NUM (insn)] == insn)
2013 basic_block_head[BLOCK_NUM (insn)] = insns;
2018 /* INCR will become a NOTE and INSN won't contain a
2019 use of ADDR. If a use of ADDR was just placed in
2020 the insn before INSN, make that the next use.
2021 Otherwise, invalidate it. */
2022 if (GET_CODE (PREV_INSN (insn)) == INSN
2023 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
2024 && SET_SRC (PATTERN (PREV_INSN (insn))) == addr)
2025 reg_next_use[regno] = PREV_INSN (insn);
2027 reg_next_use[regno] = 0;
2033 /* REGNO is now used in INCR which is below INSN, but
2034 it previously wasn't live here. If we don't mark
2035 it as needed, we'll put a REG_DEAD note for it
2036 on this insn, which is incorrect. */
2037 needed[regno / REGSET_ELT_BITS]
2038 |= (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2040 /* If there are any calls between INSN and INCR, show
2041 that REGNO now crosses them. */
2042 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
2043 if (GET_CODE (temp) == CALL_INSN)
2044 reg_n_calls_crossed[regno]++;
2049 /* We have found a suitable auto-increment: do POST_INC around
2050 the register here, and patch out the increment instruction
2052 XEXP (x, 0) = gen_rtx ((INTVAL (XEXP (y, 1)) == size
2053 ? (offset ? PRE_INC : POST_INC)
2054 : (offset ? PRE_DEC : POST_DEC)),
2057 /* Record that this insn has an implicit side effect. */
2059 = gen_rtx (EXPR_LIST, REG_INC, addr, REG_NOTES (insn));
2061 /* Modify the old increment-insn to simply copy
2062 the already-incremented value of our register. */
2063 SET_SRC (PATTERN (incr)) = addr;
2064 /* Indicate insn must be re-recognized. */
2065 INSN_CODE (incr) = -1;
2067 /* If that makes it a no-op (copying the register into itself)
2068 then delete it so it won't appear to be a "use" and a "set"
2069 of this register. */
2070 if (SET_DEST (PATTERN (incr)) == addr)
2072 PUT_CODE (incr, NOTE);
2073 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
2074 NOTE_SOURCE_FILE (incr) = 0;
2077 if (regno >= FIRST_PSEUDO_REGISTER)
2079 /* Count an extra reference to the reg. When a reg is
2080 incremented, spilling it is worse, so we want to make
2081 that less likely. */
2082 reg_n_refs[regno] += loop_depth;
2083 /* Count the increment as a setting of the register,
2084 even though it isn't a SET in rtl. */
2085 reg_n_sets[regno]++;
2091 #endif /* AUTO_INC_DEC */
2093 /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
2094 This is done assuming the registers needed from X
2095 are those that have 1-bits in NEEDED.
2097 On the final pass, FINAL is 1. This means try for autoincrement
2098 and count the uses and deaths of each pseudo-reg.
2100 INSN is the containing instruction. If INSN is dead, this function is not
2104 mark_used_regs (needed, live, x, final, insn)
2111 register RTX_CODE code;
2116 code = GET_CODE (x);
2138 /* Invalidate the data for the last MEM stored. We could do this only
2139 if the addresses conflict, but this doesn't seem worthwhile. */
2144 find_auto_inc (needed, x, insn);
2149 /* See a register other than being set
2150 => mark it as needed. */
2154 register int offset = regno / REGSET_ELT_BITS;
2155 register REGSET_ELT_TYPE bit
2156 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2157 int all_needed = (needed[offset] & bit) != 0;
2158 int some_needed = (needed[offset] & bit) != 0;
2160 live[offset] |= bit;
2161 /* A hard reg in a wide mode may really be multiple registers.
2162 If so, mark all of them just like the first. */
2163 if (regno < FIRST_PSEUDO_REGISTER)
2167 /* For stack ptr or fixed arg pointer,
2168 nothing below can be necessary, so waste no more time. */
2169 if (regno == STACK_POINTER_REGNUM
2170 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2171 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2173 || regno == FRAME_POINTER_REGNUM)
2175 /* If this is a register we are going to try to eliminate,
2176 don't mark it live here. If we are successful in
2177 eliminating it, it need not be live unless it is used for
2178 pseudos, in which case it will have been set live when
2179 it was allocated to the pseudos. If the register will not
2180 be eliminated, reload will set it live at that point. */
2182 if (! TEST_HARD_REG_BIT (elim_reg_set, regno))
2183 regs_ever_live[regno] = 1;
2186 /* No death notes for global register variables;
2187 their values are live after this function exits. */
2188 if (global_regs[regno])
2191 reg_next_use[regno] = insn;
2195 n = HARD_REGNO_NREGS (regno, GET_MODE (x));
2198 live[(regno + n) / REGSET_ELT_BITS]
2199 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
2201 |= (needed[(regno + n) / REGSET_ELT_BITS]
2202 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2204 &= (needed[(regno + n) / REGSET_ELT_BITS]
2205 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2210 /* Record where each reg is used, so when the reg
2211 is set we know the next insn that uses it. */
2213 reg_next_use[regno] = insn;
2215 if (regno < FIRST_PSEUDO_REGISTER)
2217 /* If a hard reg is being used,
2218 record that this function does use it. */
2220 i = HARD_REGNO_NREGS (regno, GET_MODE (x));
2224 regs_ever_live[regno + --i] = 1;
2229 /* Keep track of which basic block each reg appears in. */
2231 register int blocknum = BLOCK_NUM (insn);
2233 if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
2234 reg_basic_block[regno] = blocknum;
2235 else if (reg_basic_block[regno] != blocknum)
2236 reg_basic_block[regno] = REG_BLOCK_GLOBAL;
2238 /* Count (weighted) number of uses of each reg. */
2240 reg_n_refs[regno] += loop_depth;
2243 /* Record and count the insns in which a reg dies.
2244 If it is used in this insn and was dead below the insn
2245 then it dies in this insn. If it was set in this insn,
2246 we do not make a REG_DEAD note; likewise if we already
2247 made such a note. */
2250 && ! dead_or_set_p (insn, x)
2252 && (regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
2256 /* If none of the words in X is needed, make a REG_DEAD
2257 note. Otherwise, we must make partial REG_DEAD notes. */
2261 = gen_rtx (EXPR_LIST, REG_DEAD, x, REG_NOTES (insn));
2262 reg_n_deaths[regno]++;
2268 /* Don't make a REG_DEAD note for a part of a register
2269 that is set in the insn. */
2271 for (i = HARD_REGNO_NREGS (regno, GET_MODE (x)) - 1;
2273 if ((needed[(regno + i) / REGSET_ELT_BITS]
2274 & ((REGSET_ELT_TYPE) 1
2275 << ((regno + i) % REGSET_ELT_BITS))) == 0
2276 && ! dead_or_set_regno_p (insn, regno + i))
2278 = gen_rtx (EXPR_LIST, REG_DEAD,
2279 gen_rtx (REG, word_mode, regno + i),
2289 register rtx testreg = SET_DEST (x);
2292 /* If storing into MEM, don't show it as being used. But do
2293 show the address as being used. */
2294 if (GET_CODE (testreg) == MEM)
2298 find_auto_inc (needed, testreg, insn);
2300 mark_used_regs (needed, live, XEXP (testreg, 0), final, insn);
2301 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2305 /* Storing in STRICT_LOW_PART is like storing in a reg
2306 in that this SET might be dead, so ignore it in TESTREG.
2307 but in some other ways it is like using the reg.
2309 Storing in a SUBREG or a bit field is like storing the entire
2310 register in that if the register's value is not used
2311 then this SET is not needed. */
2312 while (GET_CODE (testreg) == STRICT_LOW_PART
2313 || GET_CODE (testreg) == ZERO_EXTRACT
2314 || GET_CODE (testreg) == SIGN_EXTRACT
2315 || GET_CODE (testreg) == SUBREG)
2317 /* Modifying a single register in an alternate mode
2318 does not use any of the old value. But these other
2319 ways of storing in a register do use the old value. */
2320 if (GET_CODE (testreg) == SUBREG
2321 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
2326 testreg = XEXP (testreg, 0);
2329 /* If this is a store into a register,
2330 recursively scan the value being stored. */
2332 if (GET_CODE (testreg) == REG
2333 && (regno = REGNO (testreg), regno != FRAME_POINTER_REGNUM)
2334 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2335 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2338 /* We used to exclude global_regs here, but that seems wrong.
2339 Storing in them is like storing in mem. */
2341 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2343 mark_used_regs (needed, live, SET_DEST (x), final, insn);
2350 /* If exiting needs the right stack value, consider this insn as
2351 using the stack pointer. In any event, consider it as using
2352 all global registers. */
2354 #ifdef EXIT_IGNORE_STACK
2355 if (! EXIT_IGNORE_STACK
2356 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
2358 live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
2359 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
2361 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2363 live[i / REGSET_ELT_BITS]
2364 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
2368 /* Recursively scan the operands of this expression. */
2371 register char *fmt = GET_RTX_FORMAT (code);
2374 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2378 /* Tail recursive case: save a function call level. */
2384 mark_used_regs (needed, live, XEXP (x, i), final, insn);
2386 else if (fmt[i] == 'E')
2389 for (j = 0; j < XVECLEN (x, i); j++)
2390 mark_used_regs (needed, live, XVECEXP (x, i, j), final, insn);
2399 try_pre_increment_1 (insn)
2402 /* Find the next use of this reg. If in same basic block,
2403 make it do pre-increment or pre-decrement if appropriate. */
2404 rtx x = PATTERN (insn);
2405 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
2406 * INTVAL (XEXP (SET_SRC (x), 1)));
2407 int regno = REGNO (SET_DEST (x));
2408 rtx y = reg_next_use[regno];
2410 && BLOCK_NUM (y) == BLOCK_NUM (insn)
2411 && try_pre_increment (y, SET_DEST (PATTERN (insn)),
2414 /* We have found a suitable auto-increment
2415 and already changed insn Y to do it.
2416 So flush this increment-instruction. */
2417 PUT_CODE (insn, NOTE);
2418 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
2419 NOTE_SOURCE_FILE (insn) = 0;
2420 /* Count a reference to this reg for the increment
2421 insn we are deleting. When a reg is incremented.
2422 spilling it is worse, so we want to make that
2424 if (regno >= FIRST_PSEUDO_REGISTER)
2426 reg_n_refs[regno] += loop_depth;
2427 reg_n_sets[regno]++;
2434 /* Try to change INSN so that it does pre-increment or pre-decrement
2435 addressing on register REG in order to add AMOUNT to REG.
2436 AMOUNT is negative for pre-decrement.
2437 Returns 1 if the change could be made.
2438 This checks all about the validity of the result of modifying INSN. */
2441 try_pre_increment (insn, reg, amount)
2443 HOST_WIDE_INT amount;
2447 /* Nonzero if we can try to make a pre-increment or pre-decrement.
2448 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
2450 /* Nonzero if we can try to make a post-increment or post-decrement.
2451 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
2452 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
2453 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
2456 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
2459 /* From the sign of increment, see which possibilities are conceivable
2460 on this target machine. */
2461 #ifdef HAVE_PRE_INCREMENT
2465 #ifdef HAVE_POST_INCREMENT
2470 #ifdef HAVE_PRE_DECREMENT
2474 #ifdef HAVE_POST_DECREMENT
2479 if (! (pre_ok || post_ok))
2482 /* It is not safe to add a side effect to a jump insn
2483 because if the incremented register is spilled and must be reloaded
2484 there would be no way to store the incremented value back in memory. */
2486 if (GET_CODE (insn) == JUMP_INSN)
2491 use = find_use_as_address (PATTERN (insn), reg, 0);
2492 if (post_ok && (use == 0 || use == (rtx) 1))
2494 use = find_use_as_address (PATTERN (insn), reg, -amount);
2498 if (use == 0 || use == (rtx) 1)
2501 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
2504 XEXP (use, 0) = gen_rtx (amount > 0
2505 ? (do_post ? POST_INC : PRE_INC)
2506 : (do_post ? POST_DEC : PRE_DEC),
2509 /* Record that this insn now has an implicit side effect on X. */
2510 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_INC, reg, REG_NOTES (insn));
2514 #endif /* AUTO_INC_DEC */
2516 /* Find the place in the rtx X where REG is used as a memory address.
2517 Return the MEM rtx that so uses it.
2518 If PLUSCONST is nonzero, search instead for a memory address equivalent to
2519 (plus REG (const_int PLUSCONST)).
2521 If such an address does not appear, return 0.
2522 If REG appears more than once, or is used other than in such an address,
2526 find_use_as_address (x, reg, plusconst)
2531 enum rtx_code code = GET_CODE (x);
2532 char *fmt = GET_RTX_FORMAT (code);
2534 register rtx value = 0;
2537 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
2540 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
2541 && XEXP (XEXP (x, 0), 0) == reg
2542 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
2543 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
2546 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
2548 /* If REG occurs inside a MEM used in a bit-field reference,
2549 that is unacceptable. */
2550 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
2551 return (rtx) (HOST_WIDE_INT) 1;
2555 return (rtx) (HOST_WIDE_INT) 1;
2557 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2561 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
2565 return (rtx) (HOST_WIDE_INT) 1;
2570 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
2572 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
2576 return (rtx) (HOST_WIDE_INT) 1;
2584 /* Write information about registers and basic blocks into FILE.
2585 This is part of making a debugging dump. */
2588 dump_flow_info (file)
2592 static char *reg_class_names[] = REG_CLASS_NAMES;
2594 fprintf (file, "%d registers.\n", max_regno);
2596 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
2599 enum reg_class class, altclass;
2600 fprintf (file, "\nRegister %d used %d times across %d insns",
2601 i, reg_n_refs[i], reg_live_length[i]);
2602 if (reg_basic_block[i] >= 0)
2603 fprintf (file, " in block %d", reg_basic_block[i]);
2604 if (reg_n_deaths[i] != 1)
2605 fprintf (file, "; dies in %d places", reg_n_deaths[i]);
2606 if (reg_n_calls_crossed[i] == 1)
2607 fprintf (file, "; crosses 1 call");
2608 else if (reg_n_calls_crossed[i])
2609 fprintf (file, "; crosses %d calls", reg_n_calls_crossed[i]);
2610 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
2611 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
2612 class = reg_preferred_class (i);
2613 altclass = reg_alternate_class (i);
2614 if (class != GENERAL_REGS || altclass != ALL_REGS)
2616 if (altclass == ALL_REGS || class == ALL_REGS)
2617 fprintf (file, "; pref %s", reg_class_names[(int) class]);
2618 else if (altclass == NO_REGS)
2619 fprintf (file, "; %s or none", reg_class_names[(int) class]);
2621 fprintf (file, "; pref %s, else %s",
2622 reg_class_names[(int) class],
2623 reg_class_names[(int) altclass]);
2625 if (REGNO_POINTER_FLAG (i))
2626 fprintf (file, "; pointer");
2627 fprintf (file, ".\n");
2629 fprintf (file, "\n%d basic blocks.\n", n_basic_blocks);
2630 for (i = 0; i < n_basic_blocks; i++)
2632 register rtx head, jump;
2634 fprintf (file, "\nBasic block %d: first insn %d, last %d.\n",
2636 INSN_UID (basic_block_head[i]),
2637 INSN_UID (basic_block_end[i]));
2638 /* The control flow graph's storage is freed
2639 now when flow_analysis returns.
2640 Don't try to print it if it is gone. */
2641 if (basic_block_drops_in)
2643 fprintf (file, "Reached from blocks: ");
2644 head = basic_block_head[i];
2645 if (GET_CODE (head) == CODE_LABEL)
2646 for (jump = LABEL_REFS (head);
2648 jump = LABEL_NEXTREF (jump))
2650 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
2651 fprintf (file, " %d", from_block);
2653 if (basic_block_drops_in[i])
2654 fprintf (file, " previous");
2656 fprintf (file, "\nRegisters live at start:");
2657 for (regno = 0; regno < max_regno; regno++)
2659 register int offset = regno / REGSET_ELT_BITS;
2660 register REGSET_ELT_TYPE bit
2661 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2662 if (basic_block_live_at_start[i][offset] & bit)
2663 fprintf (file, " %d", regno);
2665 fprintf (file, "\n");
2667 fprintf (file, "\n");