1 /* Data flow analysis for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
21 /* This file contains the data flow analysis pass of the compiler.
22 It computes data flow information
23 which tells combine_instructions which insns to consider combining
24 and controls register allocation.
26 Additional data flow information that is too bulky to record
27 is generated during the analysis, and is used at that time to
28 create autoincrement and autodecrement addressing.
30 The first step is dividing the function into basic blocks.
31 find_basic_blocks does this. Then life_analysis determines
32 where each register is live and where it is dead.
34 ** find_basic_blocks **
36 find_basic_blocks divides the current function's rtl
37 into basic blocks. It records the beginnings and ends of the
38 basic blocks in the vectors basic_block_head and basic_block_end,
39 and the number of blocks in n_basic_blocks.
41 find_basic_blocks also finds any unreachable loops
46 life_analysis is called immediately after find_basic_blocks.
47 It uses the basic block information to determine where each
48 hard or pseudo register is live.
50 ** live-register info **
52 The information about where each register is live is in two parts:
53 the REG_NOTES of insns, and the vector basic_block_live_at_start.
55 basic_block_live_at_start has an element for each basic block,
56 and the element is a bit-vector with a bit for each hard or pseudo
57 register. The bit is 1 if the register is live at the beginning
60 Two types of elements can be added to an insn's REG_NOTES.
61 A REG_DEAD note is added to an insn's REG_NOTES for any register
62 that meets both of two conditions: The value in the register is not
63 needed in subsequent insns and the insn does not replace the value in
64 the register (in the case of multi-word hard registers, the value in
65 each register must be replaced by the insn to avoid a REG_DEAD note).
67 In the vast majority of cases, an object in a REG_DEAD note will be
68 used somewhere in the insn. The (rare) exception to this is if an
69 insn uses a multi-word hard register and only some of the registers are
70 needed in subsequent insns. In that case, REG_DEAD notes will be
71 provided for those hard registers that are not subsequently needed.
72 Partial REG_DEAD notes of this type do not occur when an insn sets
73 only some of the hard registers used in such a multi-word operand;
74 omitting REG_DEAD notes for objects stored in an insn is optional and
75 the desire to do so does not justify the complexity of the partial
78 REG_UNUSED notes are added for each register that is set by the insn
79 but is unused subsequently (if every register set by the insn is unused
80 and the insn does not reference memory or have some other side-effect,
81 the insn is deleted instead). If only part of a multi-word hard
82 register is used in a subsequent insn, REG_UNUSED notes are made for
83 the parts that will not be used.
85 To determine which registers are live after any insn, one can
86 start from the beginning of the basic block and scan insns, noting
87 which registers are set by each insn and which die there.
89 ** Other actions of life_analysis **
91 life_analysis sets up the LOG_LINKS fields of insns because the
92 information needed to do so is readily available.
94 life_analysis deletes insns whose only effect is to store a value
97 life_analysis notices cases where a reference to a register as
98 a memory address can be combined with a preceding or following
99 incrementation or decrementation of the register. The separate
100 instruction to increment or decrement is deleted and the address
101 is changed to a POST_INC or similar rtx.
103 Each time an incrementing or decrementing address is created,
104 a REG_INC element is added to the insn's REG_NOTES list.
106 life_analysis fills in certain vectors containing information about
107 register usage: reg_n_refs, reg_n_deaths, reg_n_sets, reg_live_length,
108 reg_n_calls_crosses and reg_basic_block. */
113 #include "basic-block.h"
114 #include "insn-config.h"
116 #include "hard-reg-set.h"
121 #define obstack_chunk_alloc xmalloc
122 #define obstack_chunk_free free
124 /* List of labels that must never be deleted. */
125 extern rtx forced_labels;
127 /* Get the basic block number of an insn.
128 This info should not be expected to remain available
129 after the end of life_analysis. */
131 /* This is the limit of the allocated space in the following two arrays. */
133 static int max_uid_for_flow;
135 #define BLOCK_NUM(INSN) uid_block_number[INSN_UID (INSN)]
137 /* This is where the BLOCK_NUM values are really stored.
138 This is set up by find_basic_blocks and used there and in life_analysis,
141 static int *uid_block_number;
143 /* INSN_VOLATILE (insn) is 1 if the insn refers to anything volatile. */
145 #define INSN_VOLATILE(INSN) uid_volatile[INSN_UID (INSN)]
146 static char *uid_volatile;
148 /* Number of basic blocks in the current function. */
152 /* Maximum register number used in this function, plus one. */
156 /* Maximum number of SCRATCH rtx's used in any basic block of this function. */
160 /* Number of SCRATCH rtx's in the current block. */
162 static int num_scratch;
164 /* Indexed by n, gives number of basic block that (REG n) is used in.
165 If the value is REG_BLOCK_GLOBAL (-2),
166 it means (REG n) is used in more than one basic block.
167 REG_BLOCK_UNKNOWN (-1) means it hasn't been seen yet so we don't know.
168 This information remains valid for the rest of the compilation
169 of the current function; it is used to control register allocation. */
171 int *reg_basic_block;
173 /* Indexed by n, gives number of times (REG n) is used or set, each
174 weighted by its loop-depth.
175 This information remains valid for the rest of the compilation
176 of the current function; it is used to control register allocation. */
180 /* Indexed by N, gives number of places register N dies.
181 This information remains valid for the rest of the compilation
182 of the current function; it is used to control register allocation. */
186 /* Indexed by N, gives 1 if that reg is live across any CALL_INSNs.
187 This information remains valid for the rest of the compilation
188 of the current function; it is used to control register allocation. */
190 int *reg_n_calls_crossed;
192 /* Total number of instructions at which (REG n) is live.
193 The larger this is, the less priority (REG n) gets for
194 allocation in a real register.
195 This information remains valid for the rest of the compilation
196 of the current function; it is used to control register allocation.
198 local-alloc.c may alter this number to change the priority.
200 Negative values are special.
201 -1 is used to mark a pseudo reg which has a constant or memory equivalent
202 and is used infrequently enough that it should not get a hard register.
203 -2 is used to mark a pseudo reg for a parameter, when a frame pointer
204 is not required. global.c makes an allocno for this but does
205 not try to assign a hard register to it. */
207 int *reg_live_length;
209 /* Element N is the next insn that uses (hard or pseudo) register number N
210 within the current basic block; or zero, if there is no such insn.
211 This is valid only during the final backward scan in propagate_block. */
213 static rtx *reg_next_use;
215 /* Size of a regset for the current function,
216 in (1) bytes and (2) elements. */
221 /* Element N is first insn in basic block N.
222 This info lasts until we finish compiling the function. */
224 rtx *basic_block_head;
226 /* Element N is last insn in basic block N.
227 This info lasts until we finish compiling the function. */
229 rtx *basic_block_end;
231 /* Element N is a regset describing the registers live
232 at the start of basic block N.
233 This info lasts until we finish compiling the function. */
235 regset *basic_block_live_at_start;
237 /* Regset of regs live when calls to `setjmp'-like functions happen. */
239 regset regs_live_at_setjmp;
241 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
242 that have to go in the same hard reg.
243 The first two regs in the list are a pair, and the next two
244 are another pair, etc. */
247 /* Element N is nonzero if control can drop into basic block N
248 from the preceding basic block. Freed after life_analysis. */
250 static char *basic_block_drops_in;
252 /* Element N is depth within loops of the last insn in basic block number N.
253 Freed after life_analysis. */
255 static short *basic_block_loop_depth;
257 /* Element N nonzero if basic block N can actually be reached.
258 Vector exists only during find_basic_blocks. */
260 static char *block_live_static;
262 /* Depth within loops of basic block being scanned for lifetime analysis,
263 plus one. This is the weight attached to references to registers. */
265 static int loop_depth;
267 /* During propagate_block, this is non-zero if the value of CC0 is live. */
271 /* During propagate_block, this contains the last MEM stored into. It
272 is used to eliminate consecutive stores to the same location. */
274 static rtx last_mem_set;
276 /* Set of registers that may be eliminable. These are handled specially
277 in updating regs_ever_live. */
279 static HARD_REG_SET elim_reg_set;
281 /* Forward declarations */
282 static void find_basic_blocks PROTO((rtx, rtx));
283 static int uses_reg_or_mem PROTO((rtx));
284 static void mark_label_ref PROTO((rtx, rtx, int));
285 static void life_analysis PROTO((rtx, int));
286 void allocate_for_life_analysis PROTO((void));
287 static void init_regset_vector PROTO((regset *, regset, int, int));
288 static void propagate_block PROTO((regset, rtx, rtx, int,
290 static int insn_dead_p PROTO((rtx, regset, int));
291 static int libcall_dead_p PROTO((rtx, regset, rtx, rtx));
292 static void mark_set_regs PROTO((regset, regset, rtx,
294 static void mark_set_1 PROTO((regset, regset, rtx,
296 static void find_auto_inc PROTO((regset, rtx, rtx));
297 static void mark_used_regs PROTO((regset, regset, rtx, int, rtx));
298 static int try_pre_increment_1 PROTO((rtx));
299 static int try_pre_increment PROTO((rtx, rtx, HOST_WIDE_INT));
300 static rtx find_use_as_address PROTO((rtx, rtx, HOST_WIDE_INT));
301 void dump_flow_info PROTO((FILE *));
303 /* Find basic blocks of the current function and perform data flow analysis.
304 F is the first insn of the function and NREGS the number of register numbers
308 flow_analysis (f, nregs, file)
315 rtx nonlocal_label_list = nonlocal_label_rtx_list ();
317 #ifdef ELIMINABLE_REGS
318 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
321 /* Record which registers will be eliminated. We use this in
324 CLEAR_HARD_REG_SET (elim_reg_set);
326 #ifdef ELIMINABLE_REGS
327 for (i = 0; i < sizeof eliminables / sizeof eliminables[0]; i++)
328 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
330 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
333 /* Count the basic blocks. Also find maximum insn uid value used. */
336 register RTX_CODE prev_code = JUMP_INSN;
337 register RTX_CODE code;
339 max_uid_for_flow = 0;
341 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
343 code = GET_CODE (insn);
344 if (INSN_UID (insn) > max_uid_for_flow)
345 max_uid_for_flow = INSN_UID (insn);
346 if (code == CODE_LABEL
347 || (GET_RTX_CLASS (code) == 'i'
348 && (prev_code == JUMP_INSN
349 || (prev_code == CALL_INSN
350 && nonlocal_label_list != 0)
351 || prev_code == BARRIER)))
359 /* Leave space for insns we make in some cases for auto-inc. These cases
360 are rare, so we don't need too much space. */
361 max_uid_for_flow += max_uid_for_flow / 10;
364 /* Allocate some tables that last till end of compiling this function
365 and some needed only in find_basic_blocks and life_analysis. */
368 basic_block_head = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
369 basic_block_end = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
370 basic_block_drops_in = (char *) alloca (n_basic_blocks);
371 basic_block_loop_depth = (short *) alloca (n_basic_blocks * sizeof (short));
373 = (int *) alloca ((max_uid_for_flow + 1) * sizeof (int));
374 uid_volatile = (char *) alloca (max_uid_for_flow + 1);
375 bzero (uid_volatile, max_uid_for_flow + 1);
377 find_basic_blocks (f, nonlocal_label_list);
378 life_analysis (f, nregs);
380 dump_flow_info (file);
382 basic_block_drops_in = 0;
383 uid_block_number = 0;
384 basic_block_loop_depth = 0;
387 /* Find all basic blocks of the function whose first insn is F.
388 Store the correct data in the tables that describe the basic blocks,
389 set up the chains of references for each CODE_LABEL, and
390 delete any entire basic blocks that cannot be reached.
392 NONLOCAL_LABEL_LIST is the same local variable from flow_analysis. */
395 find_basic_blocks (f, nonlocal_label_list)
396 rtx f, nonlocal_label_list;
400 register char *block_live = (char *) alloca (n_basic_blocks);
401 register char *block_marked = (char *) alloca (n_basic_blocks);
402 /* List of label_refs to all labels whose addresses are taken
404 rtx label_value_list = 0;
406 enum rtx_code prev_code, code;
409 block_live_static = block_live;
410 bzero (block_live, n_basic_blocks);
411 bzero (block_marked, n_basic_blocks);
413 /* Initialize with just block 0 reachable and no blocks marked. */
414 if (n_basic_blocks > 0)
417 /* Initialize the ref chain of each label to 0. Record where all the
418 blocks start and end and their depth in loops. For each insn, record
419 the block it is in. Also mark as reachable any blocks headed by labels
420 that must not be deleted. */
422 for (insn = f, i = -1, prev_code = JUMP_INSN, depth = 1;
423 insn; insn = NEXT_INSN (insn))
425 code = GET_CODE (insn);
428 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
430 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
434 /* A basic block starts at label, or after something that can jump. */
435 else if (code == CODE_LABEL
436 || (GET_RTX_CLASS (code) == 'i'
437 && (prev_code == JUMP_INSN
438 || (prev_code == CALL_INSN
439 && nonlocal_label_list != 0)
440 || prev_code == BARRIER)))
442 basic_block_head[++i] = insn;
443 basic_block_end[i] = insn;
444 basic_block_loop_depth[i] = depth;
446 if (code == CODE_LABEL)
448 LABEL_REFS (insn) = insn;
449 /* Any label that cannot be deleted
450 is considered to start a reachable block. */
451 if (LABEL_PRESERVE_P (insn))
456 else if (GET_RTX_CLASS (code) == 'i')
458 basic_block_end[i] = insn;
459 basic_block_loop_depth[i] = depth;
462 if (GET_RTX_CLASS (code) == 'i')
464 /* Make a list of all labels referred to other than by jumps. */
465 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
466 if (REG_NOTE_KIND (note) == REG_LABEL)
467 label_value_list = gen_rtx (EXPR_LIST, VOIDmode, XEXP (note, 0),
471 BLOCK_NUM (insn) = i;
477 if (i + 1 != n_basic_blocks)
480 /* Don't delete the labels (in this function)
481 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;
487 for (x = forced_labels; x; x = XEXP (x, 1))
488 if (! LABEL_REF_NONLOCAL_P (x))
489 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
491 /* Record which basic blocks control can drop in to. */
493 for (i = 0; i < n_basic_blocks; i++)
495 for (insn = PREV_INSN (basic_block_head[i]);
496 insn && GET_CODE (insn) == NOTE; insn = PREV_INSN (insn))
499 basic_block_drops_in[i] = insn && GET_CODE (insn) != BARRIER;
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 to all
511 the labels whose addresses are explicitly used. This is because,
512 when there are computed gotos, we can't tell which labels they jump
513 to, of all the possibilities.
515 Tablejumps and casesi insns are OK and we can recognize them by
516 a (use (label_ref)). */
518 for (insn = f; insn; insn = NEXT_INSN (insn))
519 if (GET_CODE (insn) == JUMP_INSN)
521 rtx pat = PATTERN (insn);
522 int computed_jump = 0;
524 if (GET_CODE (pat) == PARALLEL)
526 int len = XVECLEN (pat, 0);
527 int has_use_labelref = 0;
529 for (i = len - 1; i >= 0; i--)
530 if (GET_CODE (XVECEXP (pat, 0, i)) == USE
531 && (GET_CODE (XEXP (XVECEXP (pat, 0, i), 0))
533 has_use_labelref = 1;
535 if (! has_use_labelref)
536 for (i = len - 1; i >= 0; i--)
537 if (GET_CODE (XVECEXP (pat, 0, i)) == SET
538 && SET_DEST (XVECEXP (pat, 0, i)) == pc_rtx
539 && uses_reg_or_mem (SET_SRC (XVECEXP (pat, 0, i))))
542 else if (GET_CODE (pat) == SET
543 && SET_DEST (pat) == pc_rtx
544 && uses_reg_or_mem (SET_SRC (pat)))
549 for (x = label_value_list; x; x = XEXP (x, 1))
550 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
553 for (x = forced_labels; x; x = XEXP (x, 1))
554 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
559 /* Find all call insns and mark them as possibly jumping
560 to all the nonlocal goto handler labels. */
562 for (insn = f; insn; insn = NEXT_INSN (insn))
563 if (GET_CODE (insn) == CALL_INSN)
565 for (x = nonlocal_label_list; x; x = XEXP (x, 1))
566 /* Don't try marking labels that
567 were deleted as unreferenced. */
568 if (GET_CODE (XEXP (x, 0)) == CODE_LABEL)
569 mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
572 /* ??? This could be made smarter:
573 in some cases it's possible to tell that certain
574 calls will not do a nonlocal goto.
576 For example, if the nested functions that do the
577 nonlocal gotos do not have their addresses taken, then
578 only calls to those functions or to other nested
579 functions that use them could possibly do nonlocal
583 /* Pass over all blocks, marking each block that is reachable
584 and has not yet been marked.
585 Keep doing this until, in one pass, no blocks have been marked.
586 Then blocks_live and blocks_marked are identical and correct.
587 In addition, all jumps actually reachable have been marked. */
589 while (something_marked)
591 something_marked = 0;
592 for (i = 0; i < n_basic_blocks; i++)
593 if (block_live[i] && !block_marked[i])
596 something_marked = 1;
597 if (i + 1 < n_basic_blocks && basic_block_drops_in[i + 1])
598 block_live[i + 1] = 1;
599 insn = basic_block_end[i];
600 if (GET_CODE (insn) == JUMP_INSN)
601 mark_label_ref (PATTERN (insn), insn, 0);
605 /* Now delete the code for any basic blocks that can't be reached.
606 They can occur because jump_optimize does not recognize
607 unreachable loops as unreachable. */
609 for (i = 0; i < n_basic_blocks; i++)
612 insn = basic_block_head[i];
615 if (GET_CODE (insn) == BARRIER)
617 if (GET_CODE (insn) != NOTE)
619 PUT_CODE (insn, NOTE);
620 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
621 NOTE_SOURCE_FILE (insn) = 0;
623 if (insn == basic_block_end[i])
625 /* BARRIERs are between basic blocks, not part of one.
626 Delete a BARRIER if the preceding jump is deleted.
627 We cannot alter a BARRIER into a NOTE
628 because it is too short; but we can really delete
629 it because it is not part of a basic block. */
630 if (NEXT_INSN (insn) != 0
631 && GET_CODE (NEXT_INSN (insn)) == BARRIER)
632 delete_insn (NEXT_INSN (insn));
635 insn = NEXT_INSN (insn);
637 /* Each time we delete some basic blocks,
638 see if there is a jump around them that is
639 being turned into a no-op. If so, delete it. */
641 if (block_live[i - 1])
644 for (j = i; j < n_basic_blocks; j++)
648 insn = basic_block_end[i - 1];
649 if (GET_CODE (insn) == JUMP_INSN
650 /* An unconditional jump is the only possibility
651 we must check for, since a conditional one
652 would make these blocks live. */
653 && simplejump_p (insn)
654 && (label = XEXP (SET_SRC (PATTERN (insn)), 0), 1)
655 && INSN_UID (label) != 0
656 && BLOCK_NUM (label) == j)
658 PUT_CODE (insn, NOTE);
659 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
660 NOTE_SOURCE_FILE (insn) = 0;
661 if (GET_CODE (NEXT_INSN (insn)) != BARRIER)
663 delete_insn (NEXT_INSN (insn));
672 /* Return 1 if X contain a REG or MEM that is not in the constant pool. */
678 enum rtx_code code = GET_CODE (x);
684 && ! (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
685 && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))))
688 fmt = GET_RTX_FORMAT (code);
689 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
692 && uses_reg_or_mem (XEXP (x, i)))
696 for (j = 0; j < XVECLEN (x, i); j++)
697 if (uses_reg_or_mem (XVECEXP (x, i, j)))
704 /* Check expression X for label references;
705 if one is found, add INSN to the label's chain of references.
707 CHECKDUP means check for and avoid creating duplicate references
708 from the same insn. Such duplicates do no serious harm but
709 can slow life analysis. CHECKDUP is set only when duplicates
713 mark_label_ref (x, insn, checkdup)
717 register RTX_CODE code;
721 /* We can be called with NULL when scanning label_value_list. */
726 if (code == LABEL_REF)
728 register rtx label = XEXP (x, 0);
730 if (GET_CODE (label) != CODE_LABEL)
732 /* If the label was never emitted, this insn is junk,
733 but avoid a crash trying to refer to BLOCK_NUM (label).
734 This can happen as a result of a syntax error
735 and a diagnostic has already been printed. */
736 if (INSN_UID (label) == 0)
738 CONTAINING_INSN (x) = insn;
739 /* if CHECKDUP is set, check for duplicate ref from same insn
742 for (y = LABEL_REFS (label); y != label; y = LABEL_NEXTREF (y))
743 if (CONTAINING_INSN (y) == insn)
745 LABEL_NEXTREF (x) = LABEL_REFS (label);
746 LABEL_REFS (label) = x;
747 block_live_static[BLOCK_NUM (label)] = 1;
751 fmt = GET_RTX_FORMAT (code);
752 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
755 mark_label_ref (XEXP (x, i), insn, 0);
759 for (j = 0; j < XVECLEN (x, i); j++)
760 mark_label_ref (XVECEXP (x, i, j), insn, 1);
765 /* Determine which registers are live at the start of each
766 basic block of the function whose first insn is F.
767 NREGS is the number of registers used in F.
768 We allocate the vector basic_block_live_at_start
769 and the regsets that it points to, and fill them with the data.
770 regset_size and regset_bytes are also set here. */
773 life_analysis (f, nregs)
780 /* For each basic block, a bitmask of regs
781 live on exit from the block. */
782 regset *basic_block_live_at_end;
783 /* For each basic block, a bitmask of regs
784 live on entry to a successor-block of this block.
785 If this does not match basic_block_live_at_end,
786 that must be updated, and the block must be rescanned. */
787 regset *basic_block_new_live_at_end;
788 /* For each basic block, a bitmask of regs
789 whose liveness at the end of the basic block
790 can make a difference in which regs are live on entry to the block.
791 These are the regs that are set within the basic block,
792 possibly excluding those that are used after they are set. */
793 regset *basic_block_significant;
797 struct obstack flow_obstack;
799 gcc_obstack_init (&flow_obstack);
803 bzero (regs_ever_live, sizeof regs_ever_live);
805 /* Allocate and zero out many data structures
806 that will record the data from lifetime analysis. */
808 allocate_for_life_analysis ();
810 reg_next_use = (rtx *) alloca (nregs * sizeof (rtx));
811 bzero ((char *) reg_next_use, nregs * sizeof (rtx));
813 /* Set up several regset-vectors used internally within this function.
814 Their meanings are documented above, with their declarations. */
816 basic_block_live_at_end
817 = (regset *) alloca (n_basic_blocks * sizeof (regset));
819 /* Don't use alloca since that leads to a crash rather than an error message
820 if there isn't enough space.
821 Don't use oballoc since we may need to allocate other things during
822 this function on the temporary obstack. */
823 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
824 bzero ((char *) tem, n_basic_blocks * regset_bytes);
825 init_regset_vector (basic_block_live_at_end, tem,
826 n_basic_blocks, regset_bytes);
828 basic_block_new_live_at_end
829 = (regset *) alloca (n_basic_blocks * sizeof (regset));
830 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
831 bzero ((char *) tem, n_basic_blocks * regset_bytes);
832 init_regset_vector (basic_block_new_live_at_end, tem,
833 n_basic_blocks, regset_bytes);
835 basic_block_significant
836 = (regset *) alloca (n_basic_blocks * sizeof (regset));
837 tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
838 bzero ((char *) tem, n_basic_blocks * regset_bytes);
839 init_regset_vector (basic_block_significant, tem,
840 n_basic_blocks, regset_bytes);
842 /* Record which insns refer to any volatile memory
843 or for any reason can't be deleted just because they are dead stores.
844 Also, delete any insns that copy a register to itself. */
846 for (insn = f; insn; insn = NEXT_INSN (insn))
848 enum rtx_code code1 = GET_CODE (insn);
849 if (code1 == CALL_INSN)
850 INSN_VOLATILE (insn) = 1;
851 else if (code1 == INSN || code1 == JUMP_INSN)
853 /* Delete (in effect) any obvious no-op moves. */
854 if (GET_CODE (PATTERN (insn)) == SET
855 && GET_CODE (SET_DEST (PATTERN (insn))) == REG
856 && GET_CODE (SET_SRC (PATTERN (insn))) == REG
857 && REGNO (SET_DEST (PATTERN (insn))) ==
858 REGNO (SET_SRC (PATTERN (insn)))
859 /* Insns carrying these notes are useful later on. */
860 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
862 PUT_CODE (insn, NOTE);
863 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
864 NOTE_SOURCE_FILE (insn) = 0;
866 else if (GET_CODE (PATTERN (insn)) == PARALLEL)
868 /* If nothing but SETs of registers to themselves,
869 this insn can also be deleted. */
870 for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
872 rtx tem = XVECEXP (PATTERN (insn), 0, i);
874 if (GET_CODE (tem) == USE
875 || GET_CODE (tem) == CLOBBER)
878 if (GET_CODE (tem) != SET
879 || GET_CODE (SET_DEST (tem)) != REG
880 || GET_CODE (SET_SRC (tem)) != REG
881 || REGNO (SET_DEST (tem)) != REGNO (SET_SRC (tem)))
885 if (i == XVECLEN (PATTERN (insn), 0)
886 /* Insns carrying these notes are useful later on. */
887 && ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
889 PUT_CODE (insn, NOTE);
890 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
891 NOTE_SOURCE_FILE (insn) = 0;
894 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
896 else if (GET_CODE (PATTERN (insn)) != USE)
897 INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
898 /* A SET that makes space on the stack cannot be dead.
899 (Such SETs occur only for allocating variable-size data,
900 so they will always have a PLUS or MINUS according to the
901 direction of stack growth.)
902 Even if this function never uses this stack pointer value,
903 signal handlers do! */
904 else if (code1 == INSN && GET_CODE (PATTERN (insn)) == SET
905 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
906 #ifdef STACK_GROWS_DOWNWARD
907 && GET_CODE (SET_SRC (PATTERN (insn))) == MINUS
909 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
911 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx)
912 INSN_VOLATILE (insn) = 1;
916 if (n_basic_blocks > 0)
917 #ifdef EXIT_IGNORE_STACK
918 if (! EXIT_IGNORE_STACK
919 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
922 /* If exiting needs the right stack value,
923 consider the stack pointer live at the end of the function. */
924 basic_block_live_at_end[n_basic_blocks - 1]
925 [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
926 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
927 basic_block_new_live_at_end[n_basic_blocks - 1]
928 [STACK_POINTER_REGNUM / REGSET_ELT_BITS]
929 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
932 /* Mark the frame pointer is needed at the end of the function. If
933 we end up eliminating it, it will be removed from the live list
934 of each basic block by reload. */
936 if (n_basic_blocks > 0)
938 basic_block_live_at_end[n_basic_blocks - 1]
939 [FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
940 |= (REGSET_ELT_TYPE) 1 << (FRAME_POINTER_REGNUM % REGSET_ELT_BITS);
941 basic_block_new_live_at_end[n_basic_blocks - 1]
942 [FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
943 |= (REGSET_ELT_TYPE) 1 << (FRAME_POINTER_REGNUM % REGSET_ELT_BITS);
944 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
945 /* If they are different, also mark the hard frame pointer as live */
946 basic_block_live_at_end[n_basic_blocks - 1]
947 [HARD_FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
948 |= (REGSET_ELT_TYPE) 1 << (HARD_FRAME_POINTER_REGNUM
950 basic_block_new_live_at_end[n_basic_blocks - 1]
951 [HARD_FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
952 |= (REGSET_ELT_TYPE) 1 << (HARD_FRAME_POINTER_REGNUM
957 /* Mark all global registers as being live at the end of the function
958 since they may be referenced by our caller. */
960 if (n_basic_blocks > 0)
961 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
964 basic_block_live_at_end[n_basic_blocks - 1]
965 [i / REGSET_ELT_BITS]
966 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
967 basic_block_new_live_at_end[n_basic_blocks - 1]
968 [i / REGSET_ELT_BITS]
969 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
972 /* Propagate life info through the basic blocks
973 around the graph of basic blocks.
975 This is a relaxation process: each time a new register
976 is live at the end of the basic block, we must scan the block
977 to determine which registers are, as a consequence, live at the beginning
978 of that block. These registers must then be marked live at the ends
979 of all the blocks that can transfer control to that block.
980 The process continues until it reaches a fixed point. */
987 for (i = n_basic_blocks - 1; i >= 0; i--)
989 int consider = first_pass;
990 int must_rescan = first_pass;
995 /* Set CONSIDER if this block needs thinking about at all
996 (that is, if the regs live now at the end of it
997 are not the same as were live at the end of it when
998 we last thought about it).
999 Set must_rescan if it needs to be thought about
1000 instruction by instruction (that is, if any additional
1001 reg that is live at the end now but was not live there before
1002 is one of the significant regs of this basic block). */
1004 for (j = 0; j < regset_size; j++)
1006 register REGSET_ELT_TYPE x
1007 = (basic_block_new_live_at_end[i][j]
1008 & ~basic_block_live_at_end[i][j]);
1011 if (x & basic_block_significant[i][j])
1023 /* The live_at_start of this block may be changing,
1024 so another pass will be required after this one. */
1029 /* No complete rescan needed;
1030 just record those variables newly known live at end
1031 as live at start as well. */
1032 for (j = 0; j < regset_size; j++)
1034 register REGSET_ELT_TYPE x
1035 = (basic_block_new_live_at_end[i][j]
1036 & ~basic_block_live_at_end[i][j]);
1037 basic_block_live_at_start[i][j] |= x;
1038 basic_block_live_at_end[i][j] |= x;
1043 /* Update the basic_block_live_at_start
1044 by propagation backwards through the block. */
1045 bcopy ((char *) basic_block_new_live_at_end[i],
1046 (char *) basic_block_live_at_end[i], regset_bytes);
1047 bcopy ((char *) basic_block_live_at_end[i],
1048 (char *) basic_block_live_at_start[i], regset_bytes);
1049 propagate_block (basic_block_live_at_start[i],
1050 basic_block_head[i], basic_block_end[i], 0,
1051 first_pass ? basic_block_significant[i]
1057 register rtx jump, head;
1058 /* Update the basic_block_new_live_at_end's of the block
1059 that falls through into this one (if any). */
1060 head = basic_block_head[i];
1061 jump = PREV_INSN (head);
1062 if (basic_block_drops_in[i])
1064 register int from_block = BLOCK_NUM (jump);
1066 for (j = 0; j < regset_size; j++)
1067 basic_block_new_live_at_end[from_block][j]
1068 |= basic_block_live_at_start[i][j];
1070 /* Update the basic_block_new_live_at_end's of
1071 all the blocks that jump to this one. */
1072 if (GET_CODE (head) == CODE_LABEL)
1073 for (jump = LABEL_REFS (head);
1075 jump = LABEL_NEXTREF (jump))
1077 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
1079 for (j = 0; j < regset_size; j++)
1080 basic_block_new_live_at_end[from_block][j]
1081 |= basic_block_live_at_start[i][j];
1091 /* The only pseudos that are live at the beginning of the function are
1092 those that were not set anywhere in the function. local-alloc doesn't
1093 know how to handle these correctly, so mark them as not local to any
1096 if (n_basic_blocks > 0)
1097 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
1098 if (basic_block_live_at_start[0][i / REGSET_ELT_BITS]
1099 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
1100 reg_basic_block[i] = REG_BLOCK_GLOBAL;
1102 /* Now the life information is accurate.
1103 Make one more pass over each basic block
1104 to delete dead stores, create autoincrement addressing
1105 and record how many times each register is used, is set, or dies.
1107 To save time, we operate directly in basic_block_live_at_end[i],
1108 thus destroying it (in fact, converting it into a copy of
1109 basic_block_live_at_start[i]). This is ok now because
1110 basic_block_live_at_end[i] is no longer used past this point. */
1114 for (i = 0; i < n_basic_blocks; i++)
1116 propagate_block (basic_block_live_at_end[i],
1117 basic_block_head[i], basic_block_end[i], 1,
1125 /* Something live during a setjmp should not be put in a register
1126 on certain machines which restore regs from stack frames
1127 rather than from the jmpbuf.
1128 But we don't need to do this for the user's variables, since
1129 ANSI says only volatile variables need this. */
1130 #ifdef LONGJMP_RESTORE_FROM_STACK
1131 for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1132 if (regs_live_at_setjmp[i / REGSET_ELT_BITS]
1133 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS))
1134 && regno_reg_rtx[i] != 0 && ! REG_USERVAR_P (regno_reg_rtx[i]))
1136 reg_live_length[i] = -1;
1137 reg_basic_block[i] = -1;
1142 /* We have a problem with any pseudoreg that
1143 lives across the setjmp. ANSI says that if a
1144 user variable does not change in value
1145 between the setjmp and the longjmp, then the longjmp preserves it.
1146 This includes longjmp from a place where the pseudo appears dead.
1147 (In principle, the value still exists if it is in scope.)
1148 If the pseudo goes in a hard reg, some other value may occupy
1149 that hard reg where this pseudo is dead, thus clobbering the pseudo.
1150 Conclusion: such a pseudo must not go in a hard reg. */
1151 for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1152 if ((regs_live_at_setjmp[i / REGSET_ELT_BITS]
1153 & ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
1154 && regno_reg_rtx[i] != 0)
1156 reg_live_length[i] = -1;
1157 reg_basic_block[i] = -1;
1160 obstack_free (&flow_obstack, NULL_PTR);
1163 /* Subroutines of life analysis. */
1165 /* Allocate the permanent data structures that represent the results
1166 of life analysis. Not static since used also for stupid life analysis. */
1169 allocate_for_life_analysis ()
1172 register regset tem;
1174 regset_size = ((max_regno + REGSET_ELT_BITS - 1) / REGSET_ELT_BITS);
1175 regset_bytes = regset_size * sizeof (*(regset)0);
1177 reg_n_refs = (int *) oballoc (max_regno * sizeof (int));
1178 bzero ((char *) reg_n_refs, max_regno * sizeof (int));
1180 reg_n_sets = (short *) oballoc (max_regno * sizeof (short));
1181 bzero ((char *) reg_n_sets, max_regno * sizeof (short));
1183 reg_n_deaths = (short *) oballoc (max_regno * sizeof (short));
1184 bzero ((char *) reg_n_deaths, max_regno * sizeof (short));
1186 reg_live_length = (int *) oballoc (max_regno * sizeof (int));
1187 bzero ((char *) reg_live_length, max_regno * sizeof (int));
1189 reg_n_calls_crossed = (int *) oballoc (max_regno * sizeof (int));
1190 bzero ((char *) reg_n_calls_crossed, max_regno * sizeof (int));
1192 reg_basic_block = (int *) oballoc (max_regno * sizeof (int));
1193 for (i = 0; i < max_regno; i++)
1194 reg_basic_block[i] = REG_BLOCK_UNKNOWN;
1196 basic_block_live_at_start
1197 = (regset *) oballoc (n_basic_blocks * sizeof (regset));
1198 tem = (regset) oballoc (n_basic_blocks * regset_bytes);
1199 bzero ((char *) tem, n_basic_blocks * regset_bytes);
1200 init_regset_vector (basic_block_live_at_start, tem,
1201 n_basic_blocks, regset_bytes);
1203 regs_live_at_setjmp = (regset) oballoc (regset_bytes);
1204 bzero ((char *) regs_live_at_setjmp, regset_bytes);
1207 /* Make each element of VECTOR point at a regset,
1208 taking the space for all those regsets from SPACE.
1209 SPACE is of type regset, but it is really as long as NELTS regsets.
1210 BYTES_PER_ELT is the number of bytes in one regset. */
1213 init_regset_vector (vector, space, nelts, bytes_per_elt)
1220 register regset p = space;
1222 for (i = 0; i < nelts; i++)
1225 p += bytes_per_elt / sizeof (*p);
1229 /* Compute the registers live at the beginning of a basic block
1230 from those live at the end.
1232 When called, OLD contains those live at the end.
1233 On return, it contains those live at the beginning.
1234 FIRST and LAST are the first and last insns of the basic block.
1236 FINAL is nonzero if we are doing the final pass which is not
1237 for computing the life info (since that has already been done)
1238 but for acting on it. On this pass, we delete dead stores,
1239 set up the logical links and dead-variables lists of instructions,
1240 and merge instructions for autoincrement and autodecrement addresses.
1242 SIGNIFICANT is nonzero only the first time for each basic block.
1243 If it is nonzero, it points to a regset in which we store
1244 a 1 for each register that is set within the block.
1246 BNUM is the number of the basic block. */
1249 propagate_block (old, first, last, final, significant, bnum)
1250 register regset old;
1262 /* The following variables are used only if FINAL is nonzero. */
1263 /* This vector gets one element for each reg that has been live
1264 at any point in the basic block that has been scanned so far.
1265 SOMETIMES_MAX says how many elements are in use so far.
1266 In each element, OFFSET is the byte-number within a regset
1267 for the register described by the element, and BIT is a mask
1268 for that register's bit within the byte. */
1269 register struct sometimes { short offset; short bit; } *regs_sometimes_live;
1270 int sometimes_max = 0;
1271 /* This regset has 1 for each reg that we have seen live so far.
1272 It and REGS_SOMETIMES_LIVE are updated together. */
1275 /* The loop depth may change in the middle of a basic block. Since we
1276 scan from end to beginning, we start with the depth at the end of the
1277 current basic block, and adjust as we pass ends and starts of loops. */
1278 loop_depth = basic_block_loop_depth[bnum];
1280 dead = (regset) alloca (regset_bytes);
1281 live = (regset) alloca (regset_bytes);
1286 /* Include any notes at the end of the block in the scan.
1287 This is in case the block ends with a call to setjmp. */
1289 while (NEXT_INSN (last) != 0 && GET_CODE (NEXT_INSN (last)) == NOTE)
1291 /* Look for loop boundaries, we are going forward here. */
1292 last = NEXT_INSN (last);
1293 if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_BEG)
1295 else if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_END)
1301 register int i, offset;
1302 REGSET_ELT_TYPE bit;
1305 maxlive = (regset) alloca (regset_bytes);
1306 bcopy ((char *) old, (char *) maxlive, regset_bytes);
1308 = (struct sometimes *) alloca (max_regno * sizeof (struct sometimes));
1310 /* Process the regs live at the end of the block.
1311 Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
1312 Also mark them as not local to any one basic block. */
1314 for (offset = 0, i = 0; offset < regset_size; offset++)
1315 for (bit = 1; bit; bit <<= 1, i++)
1319 if (old[offset] & bit)
1321 reg_basic_block[i] = REG_BLOCK_GLOBAL;
1322 regs_sometimes_live[sometimes_max].offset = offset;
1323 regs_sometimes_live[sometimes_max].bit = i % REGSET_ELT_BITS;
1329 /* Scan the block an insn at a time from end to beginning. */
1331 for (insn = last; ; insn = prev)
1333 prev = PREV_INSN (insn);
1335 /* Look for loop boundaries, remembering that we are going backwards. */
1336 if (GET_CODE (insn) == NOTE
1337 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1339 else if (GET_CODE (insn) == NOTE
1340 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1343 /* If we have LOOP_DEPTH == 0, there has been a bookkeeping error.
1344 Abort now rather than setting register status incorrectly. */
1345 if (loop_depth == 0)
1348 /* If this is a call to `setjmp' et al,
1349 warn if any non-volatile datum is live. */
1351 if (final && GET_CODE (insn) == NOTE
1352 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
1355 for (i = 0; i < regset_size; i++)
1356 regs_live_at_setjmp[i] |= old[i];
1359 /* Update the life-status of regs for this insn.
1360 First DEAD gets which regs are set in this insn
1361 then LIVE gets which regs are used in this insn.
1362 Then the regs live before the insn
1363 are those live after, with DEAD regs turned off,
1364 and then LIVE regs turned on. */
1366 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
1369 rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1371 = (insn_dead_p (PATTERN (insn), old, 0)
1372 /* Don't delete something that refers to volatile storage! */
1373 && ! INSN_VOLATILE (insn));
1375 = (insn_is_dead && note != 0
1376 && libcall_dead_p (PATTERN (insn), old, note, insn));
1378 /* If an instruction consists of just dead store(s) on final pass,
1379 "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
1380 We could really delete it with delete_insn, but that
1381 can cause trouble for first or last insn in a basic block. */
1382 if (final && insn_is_dead)
1384 PUT_CODE (insn, NOTE);
1385 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
1386 NOTE_SOURCE_FILE (insn) = 0;
1388 /* CC0 is now known to be dead. Either this insn used it,
1389 in which case it doesn't anymore, or clobbered it,
1390 so the next insn can't use it. */
1393 /* If this insn is copying the return value from a library call,
1394 delete the entire library call. */
1395 if (libcall_is_dead)
1397 rtx first = XEXP (note, 0);
1399 while (INSN_DELETED_P (first))
1400 first = NEXT_INSN (first);
1405 NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED;
1406 NOTE_SOURCE_FILE (p) = 0;
1412 for (i = 0; i < regset_size; i++)
1414 dead[i] = 0; /* Faster than bzero here */
1415 live[i] = 0; /* since regset_size is usually small */
1418 /* See if this is an increment or decrement that can be
1419 merged into a following memory address. */
1422 register rtx x = PATTERN (insn);
1423 /* Does this instruction increment or decrement a register? */
1424 if (final && GET_CODE (x) == SET
1425 && GET_CODE (SET_DEST (x)) == REG
1426 && (GET_CODE (SET_SRC (x)) == PLUS
1427 || GET_CODE (SET_SRC (x)) == MINUS)
1428 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1429 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1430 /* Ok, look for a following memory ref we can combine with.
1431 If one is found, change the memory ref to a PRE_INC
1432 or PRE_DEC, cancel this insn, and return 1.
1433 Return 0 if nothing has been done. */
1434 && try_pre_increment_1 (insn))
1437 #endif /* AUTO_INC_DEC */
1439 /* If this is not the final pass, and this insn is copying the
1440 value of a library call and it's dead, don't scan the
1441 insns that perform the library call, so that the call's
1442 arguments are not marked live. */
1443 if (libcall_is_dead)
1445 /* Mark the dest reg as `significant'. */
1446 mark_set_regs (old, dead, PATTERN (insn), NULL_RTX, significant);
1448 insn = XEXP (note, 0);
1449 prev = PREV_INSN (insn);
1451 else if (GET_CODE (PATTERN (insn)) == SET
1452 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1453 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1454 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1455 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1456 /* We have an insn to pop a constant amount off the stack.
1457 (Such insns use PLUS regardless of the direction of the stack,
1458 and any insn to adjust the stack by a constant is always a pop.)
1459 These insns, if not dead stores, have no effect on life. */
1463 /* LIVE gets the regs used in INSN;
1464 DEAD gets those set by it. Dead insns don't make anything
1467 mark_set_regs (old, dead, PATTERN (insn),
1468 final ? insn : NULL_RTX, significant);
1470 /* If an insn doesn't use CC0, it becomes dead since we
1471 assume that every insn clobbers it. So show it dead here;
1472 mark_used_regs will set it live if it is referenced. */
1476 mark_used_regs (old, live, PATTERN (insn), final, insn);
1478 /* Sometimes we may have inserted something before INSN (such as
1479 a move) when we make an auto-inc. So ensure we will scan
1482 prev = PREV_INSN (insn);
1485 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1491 for (note = CALL_INSN_FUNCTION_USAGE (insn);
1493 note = XEXP (note, 1))
1494 if (GET_CODE (XEXP (note, 0)) == USE)
1495 mark_used_regs (old, live, SET_DEST (XEXP (note, 0)),
1498 /* Each call clobbers all call-clobbered regs that are not
1499 global. Note that the function-value reg is a
1500 call-clobbered reg, and mark_set_regs has already had
1501 a chance to handle it. */
1503 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1504 if (call_used_regs[i] && ! global_regs[i])
1505 dead[i / REGSET_ELT_BITS]
1506 |= ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS));
1508 /* The stack ptr is used (honorarily) by a CALL insn. */
1509 live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
1510 |= ((REGSET_ELT_TYPE) 1
1511 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS));
1513 /* Calls may also reference any of the global registers,
1514 so they are made live. */
1516 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1518 live[i / REGSET_ELT_BITS]
1519 |= ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS));
1521 /* Calls also clobber memory. */
1525 /* Update OLD for the registers used or set. */
1526 for (i = 0; i < regset_size; i++)
1532 if (GET_CODE (insn) == CALL_INSN && final)
1534 /* Any regs live at the time of a call instruction
1535 must not go in a register clobbered by calls.
1536 Find all regs now live and record this for them. */
1538 register struct sometimes *p = regs_sometimes_live;
1540 for (i = 0; i < sometimes_max; i++, p++)
1541 if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
1542 reg_n_calls_crossed[p->offset * REGSET_ELT_BITS + p->bit]+= 1;
1546 /* On final pass, add any additional sometimes-live regs
1547 into MAXLIVE and REGS_SOMETIMES_LIVE.
1548 Also update counts of how many insns each reg is live at. */
1552 for (i = 0; i < regset_size; i++)
1554 register REGSET_ELT_TYPE diff = live[i] & ~maxlive[i];
1560 for (regno = 0; diff && regno < REGSET_ELT_BITS; regno++)
1561 if (diff & ((REGSET_ELT_TYPE) 1 << regno))
1563 regs_sometimes_live[sometimes_max].offset = i;
1564 regs_sometimes_live[sometimes_max].bit = regno;
1565 diff &= ~ ((REGSET_ELT_TYPE) 1 << regno);
1572 register struct sometimes *p = regs_sometimes_live;
1573 for (i = 0; i < sometimes_max; i++, p++)
1575 if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
1576 reg_live_length[p->offset * REGSET_ELT_BITS + p->bit]++;
1586 if (num_scratch > max_scratch)
1587 max_scratch = num_scratch;
1590 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1591 (SET expressions whose destinations are registers dead after the insn).
1592 NEEDED is the regset that says which regs are alive after the insn.
1594 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */
1597 insn_dead_p (x, needed, call_ok)
1602 register RTX_CODE code = GET_CODE (x);
1603 /* If setting something that's a reg or part of one,
1604 see if that register's altered value will be live. */
1608 register rtx r = SET_DEST (x);
1609 /* A SET that is a subroutine call cannot be dead. */
1610 if (! call_ok && GET_CODE (SET_SRC (x)) == CALL)
1614 if (GET_CODE (r) == CC0)
1618 if (GET_CODE (r) == MEM && last_mem_set && ! MEM_VOLATILE_P (r)
1619 && rtx_equal_p (r, last_mem_set))
1622 while (GET_CODE (r) == SUBREG
1623 || GET_CODE (r) == STRICT_LOW_PART
1624 || GET_CODE (r) == ZERO_EXTRACT
1625 || GET_CODE (r) == SIGN_EXTRACT)
1628 if (GET_CODE (r) == REG)
1630 register int regno = REGNO (r);
1631 register int offset = regno / REGSET_ELT_BITS;
1632 register REGSET_ELT_TYPE bit
1633 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
1635 /* Don't delete insns to set global regs. */
1636 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
1637 /* Make sure insns to set frame pointer aren't deleted. */
1638 || regno == FRAME_POINTER_REGNUM
1639 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1640 || regno == HARD_FRAME_POINTER_REGNUM
1642 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1643 /* Make sure insns to set arg pointer are never deleted
1644 (if the arg pointer isn't fixed, there will be a USE for
1645 it, so we can treat it normally). */
1646 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1648 || (needed[offset] & bit) != 0)
1651 /* If this is a hard register, verify that subsequent words are
1653 if (regno < FIRST_PSEUDO_REGISTER)
1655 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
1658 if ((needed[(regno + n) / REGSET_ELT_BITS]
1659 & ((REGSET_ELT_TYPE) 1
1660 << ((regno + n) % REGSET_ELT_BITS))) != 0)
1667 /* If performing several activities,
1668 insn is dead if each activity is individually dead.
1669 Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
1670 that's inside a PARALLEL doesn't make the insn worth keeping. */
1671 else if (code == PARALLEL)
1673 register int i = XVECLEN (x, 0);
1674 for (i--; i >= 0; i--)
1676 rtx elt = XVECEXP (x, 0, i);
1677 if (!insn_dead_p (elt, needed, call_ok)
1678 && GET_CODE (elt) != CLOBBER
1679 && GET_CODE (elt) != USE)
1684 /* We do not check CLOBBER or USE here.
1685 An insn consisting of just a CLOBBER or just a USE
1686 should not be deleted. */
1690 /* If X is the pattern of the last insn in a libcall, and assuming X is dead,
1691 return 1 if the entire library call is dead.
1692 This is true if X copies a register (hard or pseudo)
1693 and if the hard return reg of the call insn is dead.
1694 (The caller should have tested the destination of X already for death.)
1696 If this insn doesn't just copy a register, then we don't
1697 have an ordinary libcall. In that case, cse could not have
1698 managed to substitute the source for the dest later on,
1699 so we can assume the libcall is dead.
1701 NEEDED is the bit vector of pseudoregs live before this insn.
1702 NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
1705 libcall_dead_p (x, needed, note, insn)
1711 register RTX_CODE code = GET_CODE (x);
1715 register rtx r = SET_SRC (x);
1716 if (GET_CODE (r) == REG)
1718 rtx call = XEXP (note, 0);
1721 /* Find the call insn. */
1722 while (call != insn && GET_CODE (call) != CALL_INSN)
1723 call = NEXT_INSN (call);
1725 /* If there is none, do nothing special,
1726 since ordinary death handling can understand these insns. */
1730 /* See if the hard reg holding the value is dead.
1731 If this is a PARALLEL, find the call within it. */
1732 call = PATTERN (call);
1733 if (GET_CODE (call) == PARALLEL)
1735 for (i = XVECLEN (call, 0) - 1; i >= 0; i--)
1736 if (GET_CODE (XVECEXP (call, 0, i)) == SET
1737 && GET_CODE (SET_SRC (XVECEXP (call, 0, i))) == CALL)
1740 /* This may be a library call that is returning a value
1741 via invisible pointer. Do nothing special, since
1742 ordinary death handling can understand these insns. */
1746 call = XVECEXP (call, 0, i);
1749 return insn_dead_p (call, needed, 1);
1755 /* Return 1 if register REGNO was used before it was set.
1756 In other words, if it is live at function entry.
1757 Don't count global regster variables, though. */
1760 regno_uninitialized (regno)
1763 if (n_basic_blocks == 0
1764 || (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
1767 return (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1768 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS)));
1771 /* 1 if register REGNO was alive at a place where `setjmp' was called
1772 and was set more than once or is an argument.
1773 Such regs may be clobbered by `longjmp'. */
1776 regno_clobbered_at_setjmp (regno)
1779 if (n_basic_blocks == 0)
1782 return ((reg_n_sets[regno] > 1
1783 || (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1784 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))))
1785 && (regs_live_at_setjmp[regno / REGSET_ELT_BITS]
1786 & ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))));
1789 /* Process the registers that are set within X.
1790 Their bits are set to 1 in the regset DEAD,
1791 because they are dead prior to this insn.
1793 If INSN is nonzero, it is the insn being processed
1794 and the fact that it is nonzero implies this is the FINAL pass
1795 in propagate_block. In this case, various info about register
1796 usage is stored, LOG_LINKS fields of insns are set up. */
1799 mark_set_regs (needed, dead, x, insn, significant)
1806 register RTX_CODE code = GET_CODE (x);
1808 if (code == SET || code == CLOBBER)
1809 mark_set_1 (needed, dead, x, insn, significant);
1810 else if (code == PARALLEL)
1813 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
1815 code = GET_CODE (XVECEXP (x, 0, i));
1816 if (code == SET || code == CLOBBER)
1817 mark_set_1 (needed, dead, XVECEXP (x, 0, i), insn, significant);
1822 /* Process a single SET rtx, X. */
1825 mark_set_1 (needed, dead, x, insn, significant)
1833 register rtx reg = SET_DEST (x);
1835 /* Modifying just one hardware register of a multi-reg value
1836 or just a byte field of a register
1837 does not mean the value from before this insn is now dead.
1838 But it does mean liveness of that register at the end of the block
1841 Within mark_set_1, however, we treat it as if the register is
1842 indeed modified. mark_used_regs will, however, also treat this
1843 register as being used. Thus, we treat these insns as setting a
1844 new value for the register as a function of its old value. This
1845 cases LOG_LINKS to be made appropriately and this will help combine. */
1847 while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
1848 || GET_CODE (reg) == SIGN_EXTRACT
1849 || GET_CODE (reg) == STRICT_LOW_PART)
1850 reg = XEXP (reg, 0);
1852 /* If we are writing into memory or into a register mentioned in the
1853 address of the last thing stored into memory, show we don't know
1854 what the last store was. If we are writing memory, save the address
1855 unless it is volatile. */
1856 if (GET_CODE (reg) == MEM
1857 || (GET_CODE (reg) == REG
1858 && last_mem_set != 0 && reg_overlap_mentioned_p (reg, last_mem_set)))
1861 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
1862 /* There are no REG_INC notes for SP, so we can't assume we'll see
1863 everything that invalidates it. To be safe, don't eliminate any
1864 stores though SP; none of them should be redundant anyway. */
1865 && ! reg_mentioned_p (stack_pointer_rtx, reg))
1868 if (GET_CODE (reg) == REG
1869 && (regno = REGNO (reg), regno != FRAME_POINTER_REGNUM)
1870 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1871 && regno != HARD_FRAME_POINTER_REGNUM
1873 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1874 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1876 && ! (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
1877 /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
1879 register int offset = regno / REGSET_ELT_BITS;
1880 register REGSET_ELT_TYPE bit
1881 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
1882 REGSET_ELT_TYPE all_needed = (needed[offset] & bit);
1883 REGSET_ELT_TYPE some_needed = (needed[offset] & bit);
1885 /* Mark it as a significant register for this basic block. */
1887 significant[offset] |= bit;
1889 /* Mark it as as dead before this insn. */
1890 dead[offset] |= bit;
1892 /* A hard reg in a wide mode may really be multiple registers.
1893 If so, mark all of them just like the first. */
1894 if (regno < FIRST_PSEUDO_REGISTER)
1898 /* Nothing below is needed for the stack pointer; get out asap.
1899 Eg, log links aren't needed, since combine won't use them. */
1900 if (regno == STACK_POINTER_REGNUM)
1903 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
1907 significant[(regno + n) / REGSET_ELT_BITS]
1908 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
1909 dead[(regno + n) / REGSET_ELT_BITS]
1910 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
1912 |= (needed[(regno + n) / REGSET_ELT_BITS]
1913 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
1915 &= (needed[(regno + n) / REGSET_ELT_BITS]
1916 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
1919 /* Additional data to record if this is the final pass. */
1922 register rtx y = reg_next_use[regno];
1923 register int blocknum = BLOCK_NUM (insn);
1925 /* The next use is no longer "next", since a store intervenes. */
1926 reg_next_use[regno] = 0;
1928 /* If this is a hard reg, record this function uses the reg. */
1930 if (regno < FIRST_PSEUDO_REGISTER)
1933 int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg));
1935 for (i = regno; i < endregno; i++)
1937 regs_ever_live[i] = 1;
1943 /* Keep track of which basic blocks each reg appears in. */
1945 if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
1946 reg_basic_block[regno] = blocknum;
1947 else if (reg_basic_block[regno] != blocknum)
1948 reg_basic_block[regno] = REG_BLOCK_GLOBAL;
1950 /* Count (weighted) references, stores, etc. This counts a
1951 register twice if it is modified, but that is correct. */
1952 reg_n_sets[regno]++;
1954 reg_n_refs[regno] += loop_depth;
1956 /* The insns where a reg is live are normally counted
1957 elsewhere, but we want the count to include the insn
1958 where the reg is set, and the normal counting mechanism
1959 would not count it. */
1960 reg_live_length[regno]++;
1965 /* Make a logical link from the next following insn
1966 that uses this register, back to this insn.
1967 The following insns have already been processed.
1969 We don't build a LOG_LINK for hard registers containing
1970 in ASM_OPERANDs. If these registers get replaced,
1971 we might wind up changing the semantics of the insn,
1972 even if reload can make what appear to be valid assignments
1974 if (y && (BLOCK_NUM (y) == blocknum)
1975 && (regno >= FIRST_PSEUDO_REGISTER
1976 || asm_noperands (PATTERN (y)) < 0))
1978 = gen_rtx (INSN_LIST, VOIDmode, insn, LOG_LINKS (y));
1980 else if (! some_needed)
1982 /* Note that dead stores have already been deleted when possible
1983 If we get here, we have found a dead store that cannot
1984 be eliminated (because the same insn does something useful).
1985 Indicate this by marking the reg being set as dying here. */
1987 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
1988 reg_n_deaths[REGNO (reg)]++;
1992 /* This is a case where we have a multi-word hard register
1993 and some, but not all, of the words of the register are
1994 needed in subsequent insns. Write REG_UNUSED notes
1995 for those parts that were not needed. This case should
2000 for (i = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1;
2002 if ((needed[(regno + i) / REGSET_ELT_BITS]
2003 & ((REGSET_ELT_TYPE) 1
2004 << ((regno + i) % REGSET_ELT_BITS))) == 0)
2006 = gen_rtx (EXPR_LIST, REG_UNUSED,
2007 gen_rtx (REG, word_mode, regno + i),
2012 else if (GET_CODE (reg) == REG)
2013 reg_next_use[regno] = 0;
2015 /* If this is the last pass and this is a SCRATCH, show it will be dying
2016 here and count it. */
2017 else if (GET_CODE (reg) == SCRATCH && insn != 0)
2020 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
2027 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
2031 find_auto_inc (needed, x, insn)
2036 rtx addr = XEXP (x, 0);
2037 HOST_WIDE_INT offset = 0;
2040 /* Here we detect use of an index register which might be good for
2041 postincrement, postdecrement, preincrement, or predecrement. */
2043 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
2044 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
2046 if (GET_CODE (addr) == REG)
2049 register int size = GET_MODE_SIZE (GET_MODE (x));
2052 int regno = REGNO (addr);
2054 /* Is the next use an increment that might make auto-increment? */
2055 if ((incr = reg_next_use[regno]) != 0
2056 && (set = single_set (incr)) != 0
2057 && GET_CODE (set) == SET
2058 && BLOCK_NUM (incr) == BLOCK_NUM (insn)
2059 /* Can't add side effects to jumps; if reg is spilled and
2060 reloaded, there's no way to store back the altered value. */
2061 && GET_CODE (insn) != JUMP_INSN
2062 && (y = SET_SRC (set), GET_CODE (y) == PLUS)
2063 && XEXP (y, 0) == addr
2064 && GET_CODE (XEXP (y, 1)) == CONST_INT
2066 #ifdef HAVE_POST_INCREMENT
2067 || (INTVAL (XEXP (y, 1)) == size && offset == 0)
2069 #ifdef HAVE_POST_DECREMENT
2070 || (INTVAL (XEXP (y, 1)) == - size && offset == 0)
2072 #ifdef HAVE_PRE_INCREMENT
2073 || (INTVAL (XEXP (y, 1)) == size && offset == size)
2075 #ifdef HAVE_PRE_DECREMENT
2076 || (INTVAL (XEXP (y, 1)) == - size && offset == - size)
2079 /* Make sure this reg appears only once in this insn. */
2080 && (use = find_use_as_address (PATTERN (insn), addr, offset),
2081 use != 0 && use != (rtx) 1))
2084 rtx q = SET_DEST (set);
2086 if (dead_or_set_p (incr, addr))
2088 else if (GET_CODE (q) == REG
2089 /* PREV_INSN used here to check the semi-open interval
2091 && ! reg_used_between_p (q, PREV_INSN (insn), incr))
2093 /* We have *p followed sometime later by q = p+size.
2094 Both p and q must be live afterward,
2095 and q is not used between INSN and it's assignment.
2096 Change it to q = p, ...*q..., q = q+size.
2097 Then fall into the usual case. */
2101 emit_move_insn (q, addr);
2102 insns = get_insns ();
2105 /* If anything in INSNS have UID's that don't fit within the
2106 extra space we allocate earlier, we can't make this auto-inc.
2107 This should never happen. */
2108 for (temp = insns; temp; temp = NEXT_INSN (temp))
2110 if (INSN_UID (temp) > max_uid_for_flow)
2112 BLOCK_NUM (temp) = BLOCK_NUM (insn);
2115 emit_insns_before (insns, insn);
2117 if (basic_block_head[BLOCK_NUM (insn)] == insn)
2118 basic_block_head[BLOCK_NUM (insn)] = insns;
2123 /* INCR will become a NOTE and INSN won't contain a
2124 use of ADDR. If a use of ADDR was just placed in
2125 the insn before INSN, make that the next use.
2126 Otherwise, invalidate it. */
2127 if (GET_CODE (PREV_INSN (insn)) == INSN
2128 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
2129 && SET_SRC (PATTERN (PREV_INSN (insn))) == addr)
2130 reg_next_use[regno] = PREV_INSN (insn);
2132 reg_next_use[regno] = 0;
2138 /* REGNO is now used in INCR which is below INSN, but
2139 it previously wasn't live here. If we don't mark
2140 it as needed, we'll put a REG_DEAD note for it
2141 on this insn, which is incorrect. */
2142 needed[regno / REGSET_ELT_BITS]
2143 |= (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2145 /* If there are any calls between INSN and INCR, show
2146 that REGNO now crosses them. */
2147 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
2148 if (GET_CODE (temp) == CALL_INSN)
2149 reg_n_calls_crossed[regno]++;
2153 /* If we have found a suitable auto-increment, do
2154 POST_INC around the register here, and patch out the
2155 increment instruction that follows. */
2156 && validate_change (insn, &XEXP (x, 0),
2157 gen_rtx ((INTVAL (XEXP (y, 1)) == size
2158 ? (offset ? PRE_INC : POST_INC)
2159 : (offset ? PRE_DEC : POST_DEC)),
2162 /* Record that this insn has an implicit side effect. */
2164 = gen_rtx (EXPR_LIST, REG_INC, addr, REG_NOTES (insn));
2166 /* Modify the old increment-insn to simply copy
2167 the already-incremented value of our register. */
2168 SET_SRC (set) = addr;
2169 /* Indicate insn must be re-recognized. */
2170 INSN_CODE (incr) = -1;
2172 /* If that makes it a no-op (copying the register into itself)
2173 then delete it so it won't appear to be a "use" and a "set"
2174 of this register. */
2175 if (SET_DEST (set) == addr)
2177 PUT_CODE (incr, NOTE);
2178 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
2179 NOTE_SOURCE_FILE (incr) = 0;
2182 if (regno >= FIRST_PSEUDO_REGISTER)
2184 /* Count an extra reference to the reg. When a reg is
2185 incremented, spilling it is worse, so we want to make
2186 that less likely. */
2187 reg_n_refs[regno] += loop_depth;
2188 /* Count the increment as a setting of the register,
2189 even though it isn't a SET in rtl. */
2190 reg_n_sets[regno]++;
2196 #endif /* AUTO_INC_DEC */
2198 /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
2199 This is done assuming the registers needed from X
2200 are those that have 1-bits in NEEDED.
2202 On the final pass, FINAL is 1. This means try for autoincrement
2203 and count the uses and deaths of each pseudo-reg.
2205 INSN is the containing instruction. If INSN is dead, this function is not
2209 mark_used_regs (needed, live, x, final, insn)
2216 register RTX_CODE code;
2221 code = GET_CODE (x);
2242 /* If we are clobbering a MEM, mark any registers inside the address
2244 if (GET_CODE (XEXP (x, 0)) == MEM)
2245 mark_used_regs (needed, live, XEXP (XEXP (x, 0), 0), final, insn);
2249 /* Invalidate the data for the last MEM stored. We could do this only
2250 if the addresses conflict, but this doesn't seem worthwhile. */
2255 find_auto_inc (needed, x, insn);
2260 /* See a register other than being set
2261 => mark it as needed. */
2265 register int offset = regno / REGSET_ELT_BITS;
2266 register REGSET_ELT_TYPE bit
2267 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2268 REGSET_ELT_TYPE all_needed = needed[offset] & bit;
2269 REGSET_ELT_TYPE some_needed = needed[offset] & bit;
2271 live[offset] |= bit;
2272 /* A hard reg in a wide mode may really be multiple registers.
2273 If so, mark all of them just like the first. */
2274 if (regno < FIRST_PSEUDO_REGISTER)
2278 /* For stack ptr or fixed arg pointer,
2279 nothing below can be necessary, so waste no more time. */
2280 if (regno == STACK_POINTER_REGNUM
2281 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2282 || regno == HARD_FRAME_POINTER_REGNUM
2284 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2285 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2287 || regno == FRAME_POINTER_REGNUM)
2289 /* If this is a register we are going to try to eliminate,
2290 don't mark it live here. If we are successful in
2291 eliminating it, it need not be live unless it is used for
2292 pseudos, in which case it will have been set live when
2293 it was allocated to the pseudos. If the register will not
2294 be eliminated, reload will set it live at that point. */
2296 if (! TEST_HARD_REG_BIT (elim_reg_set, regno))
2297 regs_ever_live[regno] = 1;
2300 /* No death notes for global register variables;
2301 their values are live after this function exits. */
2302 if (global_regs[regno])
2305 reg_next_use[regno] = insn;
2309 n = HARD_REGNO_NREGS (regno, GET_MODE (x));
2312 live[(regno + n) / REGSET_ELT_BITS]
2313 |= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
2315 |= (needed[(regno + n) / REGSET_ELT_BITS]
2316 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2318 &= (needed[(regno + n) / REGSET_ELT_BITS]
2319 & (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
2324 /* Record where each reg is used, so when the reg
2325 is set we know the next insn that uses it. */
2327 reg_next_use[regno] = insn;
2329 if (regno < FIRST_PSEUDO_REGISTER)
2331 /* If a hard reg is being used,
2332 record that this function does use it. */
2334 i = HARD_REGNO_NREGS (regno, GET_MODE (x));
2338 regs_ever_live[regno + --i] = 1;
2343 /* Keep track of which basic block each reg appears in. */
2345 register int blocknum = BLOCK_NUM (insn);
2347 if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
2348 reg_basic_block[regno] = blocknum;
2349 else if (reg_basic_block[regno] != blocknum)
2350 reg_basic_block[regno] = REG_BLOCK_GLOBAL;
2352 /* Count (weighted) number of uses of each reg. */
2354 reg_n_refs[regno] += loop_depth;
2357 /* Record and count the insns in which a reg dies.
2358 If it is used in this insn and was dead below the insn
2359 then it dies in this insn. If it was set in this insn,
2360 we do not make a REG_DEAD note; likewise if we already
2361 made such a note. */
2364 && ! dead_or_set_p (insn, x)
2366 && (regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
2370 /* If none of the words in X is needed, make a REG_DEAD
2371 note. Otherwise, we must make partial REG_DEAD notes. */
2375 = gen_rtx (EXPR_LIST, REG_DEAD, x, REG_NOTES (insn));
2376 reg_n_deaths[regno]++;
2382 /* Don't make a REG_DEAD note for a part of a register
2383 that is set in the insn. */
2385 for (i = HARD_REGNO_NREGS (regno, GET_MODE (x)) - 1;
2387 if ((needed[(regno + i) / REGSET_ELT_BITS]
2388 & ((REGSET_ELT_TYPE) 1
2389 << ((regno + i) % REGSET_ELT_BITS))) == 0
2390 && ! dead_or_set_regno_p (insn, regno + i))
2392 = gen_rtx (EXPR_LIST, REG_DEAD,
2393 gen_rtx (REG, word_mode, regno + i),
2403 register rtx testreg = SET_DEST (x);
2406 /* If storing into MEM, don't show it as being used. But do
2407 show the address as being used. */
2408 if (GET_CODE (testreg) == MEM)
2412 find_auto_inc (needed, testreg, insn);
2414 mark_used_regs (needed, live, XEXP (testreg, 0), final, insn);
2415 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2419 /* Storing in STRICT_LOW_PART is like storing in a reg
2420 in that this SET might be dead, so ignore it in TESTREG.
2421 but in some other ways it is like using the reg.
2423 Storing in a SUBREG or a bit field is like storing the entire
2424 register in that if the register's value is not used
2425 then this SET is not needed. */
2426 while (GET_CODE (testreg) == STRICT_LOW_PART
2427 || GET_CODE (testreg) == ZERO_EXTRACT
2428 || GET_CODE (testreg) == SIGN_EXTRACT
2429 || GET_CODE (testreg) == SUBREG)
2431 /* Modifying a single register in an alternate mode
2432 does not use any of the old value. But these other
2433 ways of storing in a register do use the old value. */
2434 if (GET_CODE (testreg) == SUBREG
2435 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
2440 testreg = XEXP (testreg, 0);
2443 /* If this is a store into a register,
2444 recursively scan the value being stored. */
2446 if (GET_CODE (testreg) == REG
2447 && (regno = REGNO (testreg), regno != FRAME_POINTER_REGNUM)
2448 #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
2449 && regno != HARD_FRAME_POINTER_REGNUM
2451 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2452 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2455 /* We used to exclude global_regs here, but that seems wrong.
2456 Storing in them is like storing in mem. */
2458 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2460 mark_used_regs (needed, live, SET_DEST (x), final, insn);
2467 /* If exiting needs the right stack value, consider this insn as
2468 using the stack pointer. In any event, consider it as using
2469 all global registers. */
2471 #ifdef EXIT_IGNORE_STACK
2472 if (! EXIT_IGNORE_STACK
2473 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
2475 live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
2476 |= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
2478 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2480 live[i / REGSET_ELT_BITS]
2481 |= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
2485 /* Recursively scan the operands of this expression. */
2488 register char *fmt = GET_RTX_FORMAT (code);
2491 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2495 /* Tail recursive case: save a function call level. */
2501 mark_used_regs (needed, live, XEXP (x, i), final, insn);
2503 else if (fmt[i] == 'E')
2506 for (j = 0; j < XVECLEN (x, i); j++)
2507 mark_used_regs (needed, live, XVECEXP (x, i, j), final, insn);
2516 try_pre_increment_1 (insn)
2519 /* Find the next use of this reg. If in same basic block,
2520 make it do pre-increment or pre-decrement if appropriate. */
2521 rtx x = PATTERN (insn);
2522 HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
2523 * INTVAL (XEXP (SET_SRC (x), 1)));
2524 int regno = REGNO (SET_DEST (x));
2525 rtx y = reg_next_use[regno];
2527 && BLOCK_NUM (y) == BLOCK_NUM (insn)
2528 /* Don't do this if the reg dies, or gets set in y; a standard addressing
2529 mode would be better. */
2530 && ! dead_or_set_p (y, SET_DEST (x))
2531 && try_pre_increment (y, SET_DEST (PATTERN (insn)),
2534 /* We have found a suitable auto-increment
2535 and already changed insn Y to do it.
2536 So flush this increment-instruction. */
2537 PUT_CODE (insn, NOTE);
2538 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
2539 NOTE_SOURCE_FILE (insn) = 0;
2540 /* Count a reference to this reg for the increment
2541 insn we are deleting. When a reg is incremented.
2542 spilling it is worse, so we want to make that
2544 if (regno >= FIRST_PSEUDO_REGISTER)
2546 reg_n_refs[regno] += loop_depth;
2547 reg_n_sets[regno]++;
2554 /* Try to change INSN so that it does pre-increment or pre-decrement
2555 addressing on register REG in order to add AMOUNT to REG.
2556 AMOUNT is negative for pre-decrement.
2557 Returns 1 if the change could be made.
2558 This checks all about the validity of the result of modifying INSN. */
2561 try_pre_increment (insn, reg, amount)
2563 HOST_WIDE_INT amount;
2567 /* Nonzero if we can try to make a pre-increment or pre-decrement.
2568 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
2570 /* Nonzero if we can try to make a post-increment or post-decrement.
2571 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
2572 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
2573 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
2576 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
2579 /* From the sign of increment, see which possibilities are conceivable
2580 on this target machine. */
2581 #ifdef HAVE_PRE_INCREMENT
2585 #ifdef HAVE_POST_INCREMENT
2590 #ifdef HAVE_PRE_DECREMENT
2594 #ifdef HAVE_POST_DECREMENT
2599 if (! (pre_ok || post_ok))
2602 /* It is not safe to add a side effect to a jump insn
2603 because if the incremented register is spilled and must be reloaded
2604 there would be no way to store the incremented value back in memory. */
2606 if (GET_CODE (insn) == JUMP_INSN)
2611 use = find_use_as_address (PATTERN (insn), reg, 0);
2612 if (post_ok && (use == 0 || use == (rtx) 1))
2614 use = find_use_as_address (PATTERN (insn), reg, -amount);
2618 if (use == 0 || use == (rtx) 1)
2621 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
2624 /* See if this combination of instruction and addressing mode exists. */
2625 if (! validate_change (insn, &XEXP (use, 0),
2627 ? (do_post ? POST_INC : PRE_INC)
2628 : (do_post ? POST_DEC : PRE_DEC),
2632 /* Record that this insn now has an implicit side effect on X. */
2633 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_INC, reg, REG_NOTES (insn));
2637 #endif /* AUTO_INC_DEC */
2639 /* Find the place in the rtx X where REG is used as a memory address.
2640 Return the MEM rtx that so uses it.
2641 If PLUSCONST is nonzero, search instead for a memory address equivalent to
2642 (plus REG (const_int PLUSCONST)).
2644 If such an address does not appear, return 0.
2645 If REG appears more than once, or is used other than in such an address,
2649 find_use_as_address (x, reg, plusconst)
2652 HOST_WIDE_INT plusconst;
2654 enum rtx_code code = GET_CODE (x);
2655 char *fmt = GET_RTX_FORMAT (code);
2657 register rtx value = 0;
2660 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
2663 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
2664 && XEXP (XEXP (x, 0), 0) == reg
2665 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
2666 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
2669 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
2671 /* If REG occurs inside a MEM used in a bit-field reference,
2672 that is unacceptable. */
2673 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
2674 return (rtx) (HOST_WIDE_INT) 1;
2678 return (rtx) (HOST_WIDE_INT) 1;
2680 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2684 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
2688 return (rtx) (HOST_WIDE_INT) 1;
2693 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
2695 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
2699 return (rtx) (HOST_WIDE_INT) 1;
2707 /* Write information about registers and basic blocks into FILE.
2708 This is part of making a debugging dump. */
2711 dump_flow_info (file)
2715 static char *reg_class_names[] = REG_CLASS_NAMES;
2717 fprintf (file, "%d registers.\n", max_regno);
2719 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
2722 enum reg_class class, altclass;
2723 fprintf (file, "\nRegister %d used %d times across %d insns",
2724 i, reg_n_refs[i], reg_live_length[i]);
2725 if (reg_basic_block[i] >= 0)
2726 fprintf (file, " in block %d", reg_basic_block[i]);
2727 if (reg_n_deaths[i] != 1)
2728 fprintf (file, "; dies in %d places", reg_n_deaths[i]);
2729 if (reg_n_calls_crossed[i] == 1)
2730 fprintf (file, "; crosses 1 call");
2731 else if (reg_n_calls_crossed[i])
2732 fprintf (file, "; crosses %d calls", reg_n_calls_crossed[i]);
2733 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
2734 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
2735 class = reg_preferred_class (i);
2736 altclass = reg_alternate_class (i);
2737 if (class != GENERAL_REGS || altclass != ALL_REGS)
2739 if (altclass == ALL_REGS || class == ALL_REGS)
2740 fprintf (file, "; pref %s", reg_class_names[(int) class]);
2741 else if (altclass == NO_REGS)
2742 fprintf (file, "; %s or none", reg_class_names[(int) class]);
2744 fprintf (file, "; pref %s, else %s",
2745 reg_class_names[(int) class],
2746 reg_class_names[(int) altclass]);
2748 if (REGNO_POINTER_FLAG (i))
2749 fprintf (file, "; pointer");
2750 fprintf (file, ".\n");
2752 fprintf (file, "\n%d basic blocks.\n", n_basic_blocks);
2753 for (i = 0; i < n_basic_blocks; i++)
2755 register rtx head, jump;
2757 fprintf (file, "\nBasic block %d: first insn %d, last %d.\n",
2759 INSN_UID (basic_block_head[i]),
2760 INSN_UID (basic_block_end[i]));
2761 /* The control flow graph's storage is freed
2762 now when flow_analysis returns.
2763 Don't try to print it if it is gone. */
2764 if (basic_block_drops_in)
2766 fprintf (file, "Reached from blocks: ");
2767 head = basic_block_head[i];
2768 if (GET_CODE (head) == CODE_LABEL)
2769 for (jump = LABEL_REFS (head);
2771 jump = LABEL_NEXTREF (jump))
2773 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
2774 fprintf (file, " %d", from_block);
2776 if (basic_block_drops_in[i])
2777 fprintf (file, " previous");
2779 fprintf (file, "\nRegisters live at start:");
2780 for (regno = 0; regno < max_regno; regno++)
2782 register int offset = regno / REGSET_ELT_BITS;
2783 register REGSET_ELT_TYPE bit
2784 = (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
2785 if (basic_block_live_at_start[i][offset] & bit)
2786 fprintf (file, " %d", regno);
2788 fprintf (file, "\n");
2790 fprintf (file, "\n");