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 extern int xmalloc ();
127 /* List of labels that must never be deleted. */
128 extern rtx forced_labels;
130 /* Get the basic block number of an insn.
131 This info should not be expected to remain available
132 after the end of life_analysis. */
134 /* This is the limit of the allocated space in the following two arrays. */
136 static int max_uid_for_flow;
138 #define BLOCK_NUM(INSN) uid_block_number[INSN_UID (INSN)]
140 /* This is where the BLOCK_NUM values are really stored.
141 This is set up by find_basic_blocks and used there and in life_analysis,
144 static short *uid_block_number;
146 /* INSN_VOLATILE (insn) is 1 if the insn refers to anything volatile. */
148 #define INSN_VOLATILE(INSN) uid_volatile[INSN_UID (INSN)]
149 static char *uid_volatile;
151 /* Number of basic blocks in the current function. */
155 /* Maximum register number used in this function, plus one. */
159 /* Maximum number of SCRATCH rtx's used in any basic block of this function. */
163 /* Number of SCRATCH rtx's in the current block. */
165 static int num_scratch;
167 /* Indexed by n, gives number of basic block that (REG n) is used in.
168 If the value is REG_BLOCK_GLOBAL (-2),
169 it means (REG n) is used in more than one basic block.
170 REG_BLOCK_UNKNOWN (-1) means it hasn't been seen yet so we don't know.
171 This information remains valid for the rest of the compilation
172 of the current function; it is used to control register allocation. */
174 short *reg_basic_block;
176 /* Indexed by n, gives number of times (REG n) is used or set, each
177 weighted by its loop-depth.
178 This information remains valid for the rest of the compilation
179 of the current function; it is used to control register allocation. */
183 /* Indexed by N, gives number of places register N dies.
184 This information remains valid for the rest of the compilation
185 of the current function; it is used to control register allocation. */
189 /* Indexed by N, gives 1 if that reg is live across any CALL_INSNs.
190 This information remains valid for the rest of the compilation
191 of the current function; it is used to control register allocation. */
193 int *reg_n_calls_crossed;
195 /* Total number of instructions at which (REG n) is live.
196 The larger this is, the less priority (REG n) gets for
197 allocation in a real register.
198 This information remains valid for the rest of the compilation
199 of the current function; it is used to control register allocation.
201 local-alloc.c may alter this number to change the priority.
203 Negative values are special.
204 -1 is used to mark a pseudo reg which has a constant or memory equivalent
205 and is used infrequently enough that it should not get a hard register.
206 -2 is used to mark a pseudo reg for a parameter, when a frame pointer
207 is not required. global-alloc.c makes an allocno for this but does
208 not try to assign a hard register to it. */
210 int *reg_live_length;
212 /* Element N is the next insn that uses (hard or pseudo) register number N
213 within the current basic block; or zero, if there is no such insn.
214 This is valid only during the final backward scan in propagate_block. */
216 static rtx *reg_next_use;
218 /* Size of a regset for the current function,
219 in (1) bytes and (2) elements. */
224 /* Element N is first insn in basic block N.
225 This info lasts until we finish compiling the function. */
227 rtx *basic_block_head;
229 /* Element N is last insn in basic block N.
230 This info lasts until we finish compiling the function. */
232 rtx *basic_block_end;
234 /* Element N is a regset describing the registers live
235 at the start of basic block N.
236 This info lasts until we finish compiling the function. */
238 regset *basic_block_live_at_start;
240 /* Regset of regs live when calls to `setjmp'-like functions happen. */
242 regset regs_live_at_setjmp;
244 /* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
245 that have to go in the same hard reg.
246 The first two regs in the list are a pair, and the next two
247 are another pair, etc. */
250 /* Element N is nonzero if control can drop into basic block N
251 from the preceding basic block. Freed after life_analysis. */
253 static char *basic_block_drops_in;
255 /* Element N is depth within loops of the last insn in basic block number N.
256 Freed after life_analysis. */
258 static short *basic_block_loop_depth;
260 /* Element N nonzero if basic block N can actually be reached.
261 Vector exists only during find_basic_blocks. */
263 static char *block_live_static;
265 /* Depth within loops of basic block being scanned for lifetime analysis,
266 plus one. This is the weight attached to references to registers. */
268 static int loop_depth;
270 /* During propagate_block, this is non-zero if the value of CC0 is live. */
274 /* During propagate_block, this contains the last MEM stored into. It
275 is used to eliminate consecutive stores to the same location. */
277 static rtx last_mem_set;
279 /* Set of registers that may be eliminable. These are handled specially
280 in updating regs_ever_live. */
282 static HARD_REG_SET elim_reg_set;
284 /* Forward declarations */
285 static void find_basic_blocks ();
286 static void life_analysis ();
287 static void mark_label_ref ();
288 void allocate_for_life_analysis (); /* Used also in stupid_life_analysis */
289 static void init_regset_vector ();
290 static void propagate_block ();
291 static void mark_set_regs ();
292 static void mark_used_regs ();
293 static int insn_dead_p ();
294 static int libcall_dead_p ();
295 static int try_pre_increment ();
296 static int try_pre_increment_1 ();
297 static rtx find_use_as_address ();
298 void dump_flow_info ();
300 /* Find basic blocks of the current function and perform data flow analysis.
301 F is the first insn of the function and NREGS the number of register numbers
305 flow_analysis (f, nregs, file)
312 rtx nonlocal_label_list = nonlocal_label_rtx_list ();
314 #ifdef ELIMINABLE_REGS
315 static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
318 /* Record which registers will be eliminated. We use this in
321 CLEAR_HARD_REG_SET (elim_reg_set);
323 #ifdef ELIMINABLE_REGS
324 for (i = 0; i < sizeof eliminables / sizeof eliminables[0]; i++)
325 SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
327 SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
330 /* Count the basic blocks. Also find maximum insn uid value used. */
333 register RTX_CODE prev_code = JUMP_INSN;
334 register RTX_CODE code;
336 max_uid_for_flow = 0;
338 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
340 code = GET_CODE (insn);
341 if (INSN_UID (insn) > max_uid_for_flow)
342 max_uid_for_flow = INSN_UID (insn);
343 if (code == CODE_LABEL
344 || (GET_RTX_CLASS (code) == 'i'
345 && (prev_code == JUMP_INSN
346 || (prev_code == CALL_INSN
347 && nonlocal_label_list != 0)
348 || prev_code == BARRIER)))
356 /* Leave space for insns we make in some cases for auto-inc. These cases
357 are rare, so we don't need too much space. */
358 max_uid_for_flow += max_uid_for_flow / 10;
361 /* Allocate some tables that last till end of compiling this function
362 and some needed only in find_basic_blocks and life_analysis. */
365 basic_block_head = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
366 basic_block_end = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
367 basic_block_drops_in = (char *) alloca (n_basic_blocks);
368 basic_block_loop_depth = (short *) alloca (n_basic_blocks * sizeof (short));
370 = (short *) alloca ((max_uid_for_flow + 1) * sizeof (short));
371 uid_volatile = (char *) alloca (max_uid_for_flow + 1);
372 bzero (uid_volatile, max_uid_for_flow + 1);
374 find_basic_blocks (f, nonlocal_label_list);
375 life_analysis (f, nregs);
377 dump_flow_info (file);
379 basic_block_drops_in = 0;
380 uid_block_number = 0;
381 basic_block_loop_depth = 0;
384 /* Find all basic blocks of the function whose first insn is F.
385 Store the correct data in the tables that describe the basic blocks,
386 set up the chains of references for each CODE_LABEL, and
387 delete any entire basic blocks that cannot be reached.
389 NONLOCAL_LABEL_LIST is the same local variable from flow_analysis. */
392 find_basic_blocks (f, nonlocal_label_list)
393 rtx f, nonlocal_label_list;
397 register char *block_live = (char *) alloca (n_basic_blocks);
398 register char *block_marked = (char *) alloca (n_basic_blocks);
399 /* List of label_refs to all labels whose addresses are taken
401 rtx label_value_list = 0;
403 block_live_static = block_live;
404 bzero (block_live, n_basic_blocks);
405 bzero (block_marked, n_basic_blocks);
407 /* Initialize with just block 0 reachable and no blocks marked. */
408 if (n_basic_blocks > 0)
411 /* Initialize the ref chain of each label to 0. */
412 /* Record where all the blocks start and end and their depth in loops. */
413 /* For each insn, record the block it is in. */
414 /* Also mark as reachable any blocks headed by labels that
415 must not be deleted. */
418 register RTX_CODE prev_code = JUMP_INSN;
419 register RTX_CODE code;
422 for (insn = f, i = -1; insn; insn = NEXT_INSN (insn))
424 code = GET_CODE (insn);
427 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
429 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
432 /* A basic block starts at label, or after something that can jump. */
433 else if (code == CODE_LABEL
434 || (GET_RTX_CLASS (code) == 'i'
435 && (prev_code == JUMP_INSN
436 || (prev_code == CALL_INSN
437 && nonlocal_label_list != 0)
438 || prev_code == BARRIER)))
440 basic_block_head[++i] = insn;
441 basic_block_end[i] = insn;
442 basic_block_loop_depth[i] = depth;
443 if (code == CODE_LABEL)
445 LABEL_REFS (insn) = insn;
446 /* Any label that cannot be deleted
447 is considered to start a reachable block. */
448 if (LABEL_PRESERVE_P (insn))
452 else if (GET_RTX_CLASS (code) == 'i')
454 basic_block_end[i] = insn;
455 basic_block_loop_depth[i] = depth;
458 /* Make a list of all labels referred to other than by jumps. */
459 if (code == INSN || code == CALL_INSN)
461 rtx note = find_reg_note (insn, REG_LABEL, 0);
463 label_value_list = gen_rtx (EXPR_LIST, VOIDmode, XEXP (note, 0),
467 BLOCK_NUM (insn) = i;
469 /* Don't separare a CALL_INSN from following CLOBBER insns. This is
470 a kludge that will go away when each CALL_INSN records its
474 && ! (prev_code == CALL_INSN && code == INSN
475 && GET_CODE (PATTERN (insn)) == CLOBBER))
478 if (i + 1 != n_basic_blocks)
482 /* Don't delete the labels that are referenced by non-jump instructions. */
485 for (x = label_value_list; x; x = XEXP (x, 1))
486 block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
489 /* Record which basic blocks control can drop in to. */
493 for (i = 0; i < n_basic_blocks; i++)
495 register rtx insn = PREV_INSN (basic_block_head[i]);
496 /* TEMP1 is used to avoid a bug in Sequent's compiler. */
498 while (insn && GET_CODE (insn) == NOTE)
499 insn = PREV_INSN (insn);
500 temp1 = insn && GET_CODE (insn) != BARRIER;
501 basic_block_drops_in[i] = temp1;
505 /* Now find which basic blocks can actually be reached
506 and put all jump insns' LABEL_REFS onto the ref-chains
507 of their target labels. */
509 if (n_basic_blocks > 0)
511 int something_marked = 1;
513 /* Find all indirect jump insns and mark them as possibly jumping
514 to all the labels whose addresses are explicitly used.
515 This is because, when there are computed gotos,
516 we can't tell which labels they jump to, of all the possibilities. */
518 for (insn = f; insn; insn = NEXT_INSN (insn))
519 if (GET_CODE (insn) == JUMP_INSN
520 && GET_CODE (PATTERN (insn)) == SET
521 && SET_DEST (PATTERN (insn)) == pc_rtx
522 && GET_CODE (SET_SRC (PATTERN (insn))) == REG)
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, 0))
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, 0))
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 |= 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 |= 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
864 /* Mark all global registers as being live at the end of the function
865 since they may be referenced by our caller. */
867 if (n_basic_blocks > 0)
868 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
871 basic_block_live_at_end[n_basic_blocks - 1]
872 [i / REGSET_ELT_BITS] |= 1 << (i % REGSET_ELT_BITS);
873 basic_block_new_live_at_end[n_basic_blocks - 1]
874 [i / REGSET_ELT_BITS] |= 1 << (i % REGSET_ELT_BITS);
877 /* Propagate life info through the basic blocks
878 around the graph of basic blocks.
880 This is a relaxation process: each time a new register
881 is live at the end of the basic block, we must scan the block
882 to determine which registers are, as a consequence, live at the beginning
883 of that block. These registers must then be marked live at the ends
884 of all the blocks that can transfer control to that block.
885 The process continues until it reaches a fixed point. */
892 for (i = n_basic_blocks - 1; i >= 0; i--)
894 int consider = first_pass;
895 int must_rescan = first_pass;
900 /* Set CONSIDER if this block needs thinking about at all
901 (that is, if the regs live now at the end of it
902 are not the same as were live at the end of it when
903 we last thought about it).
904 Set must_rescan if it needs to be thought about
905 instruction by instruction (that is, if any additional
906 reg that is live at the end now but was not live there before
907 is one of the significant regs of this basic block). */
909 for (j = 0; j < regset_size; j++)
911 register int x = (basic_block_new_live_at_end[i][j]
912 & ~basic_block_live_at_end[i][j]);
915 if (x & basic_block_significant[i][j])
927 /* The live_at_start of this block may be changing,
928 so another pass will be required after this one. */
933 /* No complete rescan needed;
934 just record those variables newly known live at end
935 as live at start as well. */
936 for (j = 0; j < regset_size; j++)
938 register int x = basic_block_new_live_at_end[i][j]
939 & ~basic_block_live_at_end[i][j];
940 basic_block_live_at_start[i][j] |= x;
941 basic_block_live_at_end[i][j] |= x;
946 /* Update the basic_block_live_at_start
947 by propagation backwards through the block. */
948 bcopy (basic_block_new_live_at_end[i],
949 basic_block_live_at_end[i], regset_bytes);
950 bcopy (basic_block_live_at_end[i],
951 basic_block_live_at_start[i], regset_bytes);
952 propagate_block (basic_block_live_at_start[i],
953 basic_block_head[i], basic_block_end[i], 0,
954 first_pass ? basic_block_significant[i] : 0,
959 register rtx jump, head;
960 /* Update the basic_block_new_live_at_end's of the block
961 that falls through into this one (if any). */
962 head = basic_block_head[i];
963 jump = PREV_INSN (head);
964 if (basic_block_drops_in[i])
966 register int from_block = BLOCK_NUM (jump);
968 for (j = 0; j < regset_size; j++)
969 basic_block_new_live_at_end[from_block][j]
970 |= basic_block_live_at_start[i][j];
972 /* Update the basic_block_new_live_at_end's of
973 all the blocks that jump to this one. */
974 if (GET_CODE (head) == CODE_LABEL)
975 for (jump = LABEL_REFS (head);
977 jump = LABEL_NEXTREF (jump))
979 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
981 for (j = 0; j < regset_size; j++)
982 basic_block_new_live_at_end[from_block][j]
983 |= basic_block_live_at_start[i][j];
993 /* The only pseudos that are live at the beginning of the function are
994 those that were not set anywhere in the function. local-alloc doesn't
995 know how to handle these correctly, so mark them as not local to any
998 if (n_basic_blocks > 0)
999 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
1000 if (basic_block_live_at_start[0][i / REGSET_ELT_BITS]
1001 & (1 << (i % REGSET_ELT_BITS)))
1002 reg_basic_block[i] = REG_BLOCK_GLOBAL;
1004 /* Now the life information is accurate.
1005 Make one more pass over each basic block
1006 to delete dead stores, create autoincrement addressing
1007 and record how many times each register is used, is set, or dies.
1009 To save time, we operate directly in basic_block_live_at_end[i],
1010 thus destroying it (in fact, converting it into a copy of
1011 basic_block_live_at_start[i]). This is ok now because
1012 basic_block_live_at_end[i] is no longer used past this point. */
1016 for (i = 0; i < n_basic_blocks; i++)
1018 propagate_block (basic_block_live_at_end[i],
1019 basic_block_head[i], basic_block_end[i], 1, 0, i);
1026 /* Something live during a setjmp should not be put in a register
1027 on certain machines which restore regs from stack frames
1028 rather than from the jmpbuf.
1029 But we don't need to do this for the user's variables, since
1030 ANSI says only volatile variables need this. */
1031 #ifdef LONGJMP_RESTORE_FROM_STACK
1032 for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1033 if (regs_live_at_setjmp[i / REGSET_ELT_BITS] & (1 << (i % REGSET_ELT_BITS))
1034 && regno_reg_rtx[i] != 0 && ! REG_USERVAR_P (regno_reg_rtx[i]))
1036 reg_live_length[i] = -1;
1037 reg_basic_block[i] = -1;
1042 /* We have a problem with any pseudoreg that
1043 lives across the setjmp. ANSI says that if a
1044 user variable does not change in value
1045 between the setjmp and the longjmp, then the longjmp preserves it.
1046 This includes longjmp from a place where the pseudo appears dead.
1047 (In principle, the value still exists if it is in scope.)
1048 If the pseudo goes in a hard reg, some other value may occupy
1049 that hard reg where this pseudo is dead, thus clobbering the pseudo.
1050 Conclusion: such a pseudo must not go in a hard reg. */
1051 for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
1052 if (regs_live_at_setjmp[i / REGSET_ELT_BITS] & (1 << (i % REGSET_ELT_BITS))
1053 && regno_reg_rtx[i] != 0)
1055 reg_live_length[i] = -1;
1056 reg_basic_block[i] = -1;
1059 obstack_free (&flow_obstack, 0);
1062 /* Subroutines of life analysis. */
1064 /* Allocate the permanent data structures that represent the results
1065 of life analysis. Not static since used also for stupid life analysis. */
1068 allocate_for_life_analysis ()
1071 register regset tem;
1073 regset_size = ((max_regno + REGSET_ELT_BITS - 1) / REGSET_ELT_BITS);
1074 regset_bytes = regset_size * sizeof (*(regset)0);
1076 reg_n_refs = (int *) oballoc (max_regno * sizeof (int));
1077 bzero (reg_n_refs, max_regno * sizeof (int));
1079 reg_n_sets = (short *) oballoc (max_regno * sizeof (short));
1080 bzero (reg_n_sets, max_regno * sizeof (short));
1082 reg_n_deaths = (short *) oballoc (max_regno * sizeof (short));
1083 bzero (reg_n_deaths, max_regno * sizeof (short));
1085 reg_live_length = (int *) oballoc (max_regno * sizeof (int));
1086 bzero (reg_live_length, max_regno * sizeof (int));
1088 reg_n_calls_crossed = (int *) oballoc (max_regno * sizeof (int));
1089 bzero (reg_n_calls_crossed, max_regno * sizeof (int));
1091 reg_basic_block = (short *) oballoc (max_regno * sizeof (short));
1092 for (i = 0; i < max_regno; i++)
1093 reg_basic_block[i] = REG_BLOCK_UNKNOWN;
1095 basic_block_live_at_start = (regset *) oballoc (n_basic_blocks * sizeof (regset));
1096 tem = (regset) oballoc (n_basic_blocks * regset_bytes);
1097 bzero (tem, n_basic_blocks * regset_bytes);
1098 init_regset_vector (basic_block_live_at_start, tem, n_basic_blocks, regset_bytes);
1100 regs_live_at_setjmp = (regset) oballoc (regset_bytes);
1101 bzero (regs_live_at_setjmp, regset_bytes);
1104 /* Make each element of VECTOR point at a regset,
1105 taking the space for all those regsets from SPACE.
1106 SPACE is of type regset, but it is really as long as NELTS regsets.
1107 BYTES_PER_ELT is the number of bytes in one regset. */
1110 init_regset_vector (vector, space, nelts, bytes_per_elt)
1117 register regset p = space;
1119 for (i = 0; i < nelts; i++)
1122 p += bytes_per_elt / sizeof (*p);
1126 /* Compute the registers live at the beginning of a basic block
1127 from those live at the end.
1129 When called, OLD contains those live at the end.
1130 On return, it contains those live at the beginning.
1131 FIRST and LAST are the first and last insns of the basic block.
1133 FINAL is nonzero if we are doing the final pass which is not
1134 for computing the life info (since that has already been done)
1135 but for acting on it. On this pass, we delete dead stores,
1136 set up the logical links and dead-variables lists of instructions,
1137 and merge instructions for autoincrement and autodecrement addresses.
1139 SIGNIFICANT is nonzero only the first time for each basic block.
1140 If it is nonzero, it points to a regset in which we store
1141 a 1 for each register that is set within the block.
1143 BNUM is the number of the basic block. */
1146 propagate_block (old, first, last, final, significant, bnum)
1147 register regset old;
1159 /* The following variables are used only if FINAL is nonzero. */
1160 /* This vector gets one element for each reg that has been live
1161 at any point in the basic block that has been scanned so far.
1162 SOMETIMES_MAX says how many elements are in use so far.
1163 In each element, OFFSET is the byte-number within a regset
1164 for the register described by the element, and BIT is a mask
1165 for that register's bit within the byte. */
1166 register struct foo { short offset; short bit; } *regs_sometimes_live;
1167 int sometimes_max = 0;
1168 /* This regset has 1 for each reg that we have seen live so far.
1169 It and REGS_SOMETIMES_LIVE are updated together. */
1172 /* The loop depth may change in the middle of a basic block. Since we
1173 scan from end to beginning, we start with the depth at the end of the
1174 current basic block, and adjust as we pass ends and starts of loops. */
1175 loop_depth = basic_block_loop_depth[bnum];
1177 dead = (regset) alloca (regset_bytes);
1178 live = (regset) alloca (regset_bytes);
1183 /* Include any notes at the end of the block in the scan.
1184 This is in case the block ends with a call to setjmp. */
1186 while (NEXT_INSN (last) != 0 && GET_CODE (NEXT_INSN (last)) == NOTE)
1188 /* Look for loop boundaries, we are going forward here. */
1189 last = NEXT_INSN (last);
1190 if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_BEG)
1192 else if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_END)
1198 register int i, offset, bit;
1201 maxlive = (regset) alloca (regset_bytes);
1202 bcopy (old, maxlive, regset_bytes);
1204 = (struct foo *) alloca (max_regno * sizeof (struct foo));
1206 /* Process the regs live at the end of the block.
1207 Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
1208 Also mark them as not local to any one basic block. */
1210 for (offset = 0, i = 0; offset < regset_size; offset++)
1211 for (bit = 1; bit; bit <<= 1, i++)
1215 if (old[offset] & bit)
1217 reg_basic_block[i] = REG_BLOCK_GLOBAL;
1218 regs_sometimes_live[sometimes_max].offset = offset;
1219 regs_sometimes_live[sometimes_max].bit = i % REGSET_ELT_BITS;
1225 /* Scan the block an insn at a time from end to beginning. */
1227 for (insn = last; ; insn = prev)
1229 prev = PREV_INSN (insn);
1231 /* Look for loop boundaries, remembering that we are going backwards. */
1232 if (GET_CODE (insn) == NOTE
1233 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1235 else if (GET_CODE (insn) == NOTE
1236 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1239 /* If we have LOOP_DEPTH == 0, there has been a bookkeeping error.
1240 Abort now rather than setting register status incorrectly. */
1241 if (loop_depth == 0)
1244 /* If this is a call to `setjmp' et al,
1245 warn if any non-volatile datum is live. */
1247 if (final && GET_CODE (insn) == NOTE
1248 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
1251 for (i = 0; i < regset_size; i++)
1252 regs_live_at_setjmp[i] |= old[i];
1255 /* Update the life-status of regs for this insn.
1256 First DEAD gets which regs are set in this insn
1257 then LIVE gets which regs are used in this insn.
1258 Then the regs live before the insn
1259 are those live after, with DEAD regs turned off,
1260 and then LIVE regs turned on. */
1262 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
1265 rtx note = find_reg_note (insn, REG_RETVAL, 0);
1267 = (insn_dead_p (PATTERN (insn), old, 0)
1268 /* Don't delete something that refers to volatile storage! */
1269 && ! INSN_VOLATILE (insn));
1271 = (insn_is_dead && note != 0
1272 && libcall_dead_p (PATTERN (insn), old, note, insn));
1274 /* If an instruction consists of just dead store(s) on final pass,
1275 "delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
1276 We could really delete it with delete_insn, but that
1277 can cause trouble for first or last insn in a basic block. */
1278 if (final && insn_is_dead)
1280 PUT_CODE (insn, NOTE);
1281 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
1282 NOTE_SOURCE_FILE (insn) = 0;
1284 /* If this insn is copying the return value from a library call,
1285 delete the entire library call. */
1286 if (libcall_is_dead)
1288 rtx first = XEXP (note, 0);
1290 while (INSN_DELETED_P (first))
1291 first = NEXT_INSN (first);
1296 NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED;
1297 NOTE_SOURCE_FILE (p) = 0;
1303 for (i = 0; i < regset_size; i++)
1305 dead[i] = 0; /* Faster than bzero here */
1306 live[i] = 0; /* since regset_size is usually small */
1309 /* See if this is an increment or decrement that can be
1310 merged into a following memory address. */
1313 register rtx x = PATTERN (insn);
1314 /* Does this instruction increment or decrement a register? */
1315 if (final && GET_CODE (x) == SET
1316 && GET_CODE (SET_DEST (x)) == REG
1317 && (GET_CODE (SET_SRC (x)) == PLUS
1318 || GET_CODE (SET_SRC (x)) == MINUS)
1319 && XEXP (SET_SRC (x), 0) == SET_DEST (x)
1320 && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
1321 /* Ok, look for a following memory ref we can combine with.
1322 If one is found, change the memory ref to a PRE_INC
1323 or PRE_DEC, cancel this insn, and return 1.
1324 Return 0 if nothing has been done. */
1325 && try_pre_increment_1 (insn))
1328 #endif /* AUTO_INC_DEC */
1330 /* If this is not the final pass, and this insn is copying the
1331 value of a library call and it's dead, don't scan the
1332 insns that perform the library call, so that the call's
1333 arguments are not marked live. */
1334 if (libcall_is_dead)
1336 /* Mark the dest reg as `significant'. */
1337 mark_set_regs (old, dead, PATTERN (insn), 0, significant);
1339 insn = XEXP (note, 0);
1340 prev = PREV_INSN (insn);
1342 else if (GET_CODE (PATTERN (insn)) == SET
1343 && SET_DEST (PATTERN (insn)) == stack_pointer_rtx
1344 && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
1345 && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
1346 && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
1347 /* We have an insn to pop a constant amount off the stack.
1348 (Such insns use PLUS regardless of the direction of the stack,
1349 and any insn to adjust the stack by a constant is always a pop.)
1350 These insns, if not dead stores, have no effect on life. */
1354 /* LIVE gets the regs used in INSN;
1355 DEAD gets those set by it. Dead insns don't make anything
1358 mark_set_regs (old, dead, PATTERN (insn), final ? insn : 0,
1361 /* If an insn doesn't use CC0, it becomes dead since we
1362 assume that every insn clobbers it. So show it dead here;
1363 mark_used_regs will set it live if it is referenced. */
1367 mark_used_regs (old, live, PATTERN (insn), final, insn);
1369 /* Sometimes we may have inserted something before INSN (such as
1370 a move) when we make an auto-inc. So ensure we will scan
1373 prev = PREV_INSN (insn);
1376 if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
1380 /* Each call clobbers all call-clobbered regs that are not
1381 global. Note that the function-value reg is a
1382 call-clobbered reg, and mark_set_regs has already had
1383 a chance to handle it. */
1385 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1386 if (call_used_regs[i] && ! global_regs[i])
1387 dead[i / REGSET_ELT_BITS]
1388 |= (1 << (i % REGSET_ELT_BITS));
1390 /* The stack ptr is used (honorarily) by a CALL insn. */
1391 live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
1392 |= (1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS));
1394 /* Calls may also reference any of the global registers,
1395 so they are made live. */
1397 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
1399 live[i / REGSET_ELT_BITS]
1400 |= (1 << (i % REGSET_ELT_BITS));
1402 /* Calls also clobber memory. */
1406 /* Update OLD for the registers used or set. */
1407 for (i = 0; i < regset_size; i++)
1413 if (GET_CODE (insn) == CALL_INSN && final)
1415 /* Any regs live at the time of a call instruction
1416 must not go in a register clobbered by calls.
1417 Find all regs now live and record this for them. */
1419 register struct foo *p = regs_sometimes_live;
1421 for (i = 0; i < sometimes_max; i++, p++)
1422 if (old[p->offset] & (1 << p->bit))
1423 reg_n_calls_crossed[p->offset * REGSET_ELT_BITS + p->bit]+= 1;
1427 /* On final pass, add any additional sometimes-live regs
1428 into MAXLIVE and REGS_SOMETIMES_LIVE.
1429 Also update counts of how many insns each reg is live at. */
1433 for (i = 0; i < regset_size; i++)
1435 register int diff = live[i] & ~maxlive[i];
1441 for (regno = 0; diff && regno < REGSET_ELT_BITS; regno++)
1442 if (diff & (1 << regno))
1444 regs_sometimes_live[sometimes_max].offset = i;
1445 regs_sometimes_live[sometimes_max].bit = regno;
1446 diff &= ~ (1 << regno);
1453 register struct foo *p = regs_sometimes_live;
1454 for (i = 0; i < sometimes_max; i++, p++)
1456 if (old[p->offset] & (1 << p->bit))
1457 reg_live_length[p->offset * REGSET_ELT_BITS + p->bit]++;
1467 if (num_scratch > max_scratch)
1468 max_scratch = num_scratch;
1471 /* Return 1 if X (the body of an insn, or part of it) is just dead stores
1472 (SET expressions whose destinations are registers dead after the insn).
1473 NEEDED is the regset that says which regs are alive after the insn.
1475 Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */
1478 insn_dead_p (x, needed, call_ok)
1483 register RTX_CODE code = GET_CODE (x);
1484 /* If setting something that's a reg or part of one,
1485 see if that register's altered value will be live. */
1489 register rtx r = SET_DEST (x);
1490 /* A SET that is a subroutine call cannot be dead. */
1491 if (! call_ok && GET_CODE (SET_SRC (x)) == CALL)
1495 if (GET_CODE (r) == CC0)
1499 if (GET_CODE (r) == MEM && last_mem_set && ! MEM_VOLATILE_P (r)
1500 && rtx_equal_p (r, last_mem_set))
1503 while (GET_CODE (r) == SUBREG
1504 || GET_CODE (r) == STRICT_LOW_PART
1505 || GET_CODE (r) == ZERO_EXTRACT
1506 || GET_CODE (r) == SIGN_EXTRACT)
1509 if (GET_CODE (r) == REG)
1511 register int regno = REGNO (r);
1512 register int offset = regno / REGSET_ELT_BITS;
1513 register int bit = 1 << (regno % REGSET_ELT_BITS);
1515 if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
1516 /* Make sure insns to set frame pointer aren't deleted. */
1517 || regno == FRAME_POINTER_REGNUM
1518 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1519 /* Make sure insns to set arg pointer are never deleted
1520 (if the arg pointer isn't fixed, there will be a USE for
1521 it, so we can treat it normally). */
1522 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1524 || (needed[offset] & bit) != 0)
1527 /* If this is a hard register, verify that subsequent words are
1529 if (regno < FIRST_PSEUDO_REGISTER)
1531 int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
1534 if ((needed[(regno + n) / REGSET_ELT_BITS]
1535 & 1 << ((regno + n) % REGSET_ELT_BITS)) != 0)
1542 /* If performing several activities,
1543 insn is dead if each activity is individually dead.
1544 Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
1545 that's inside a PARALLEL doesn't make the insn worth keeping. */
1546 else if (code == PARALLEL)
1548 register int i = XVECLEN (x, 0);
1549 for (i--; i >= 0; i--)
1551 rtx elt = XVECEXP (x, 0, i);
1552 if (!insn_dead_p (elt, needed, call_ok)
1553 && GET_CODE (elt) != CLOBBER
1554 && GET_CODE (elt) != USE)
1559 /* We do not check CLOBBER or USE here.
1560 An insn consisting of just a CLOBBER or just a USE
1561 should not be deleted. */
1565 /* If X is the pattern of the last insn in a libcall, and assuming X is dead,
1566 return 1 if the entire library call is dead.
1567 This is true if X copies a register (hard or pseudo)
1568 and if the hard return reg of the call insn is dead.
1569 (The caller should have tested the destination of X already for death.)
1571 If this insn doesn't just copy a register, then we don't
1572 have an ordinary libcall. In that case, cse could not have
1573 managed to substitute the source for the dest later on,
1574 so we can assume the libcall is dead.
1576 NEEDED is the bit vector of pseudoregs live before this insn.
1577 NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
1580 libcall_dead_p (x, needed, note, insn)
1586 register RTX_CODE code = GET_CODE (x);
1590 register rtx r = SET_SRC (x);
1591 if (GET_CODE (r) == REG)
1593 rtx call = XEXP (note, 0);
1596 /* Find the call insn. */
1597 while (call != insn && GET_CODE (call) != CALL_INSN)
1598 call = NEXT_INSN (call);
1600 /* If there is none, do nothing special,
1601 since ordinary death handling can understand these insns. */
1605 /* See if the hard reg holding the value is dead.
1606 If this is a PARALLEL, find the call within it. */
1607 call = PATTERN (call);
1608 if (GET_CODE (call) == PARALLEL)
1610 for (i = XVECLEN (call, 0) - 1; i >= 0; i--)
1611 if (GET_CODE (XVECEXP (call, 0, i)) == SET
1612 && GET_CODE (SET_SRC (XVECEXP (call, 0, i))) == CALL)
1618 call = XVECEXP (call, 0, i);
1621 return insn_dead_p (call, needed, 1);
1627 /* Return 1 if register REGNO was used before it was set.
1628 In other words, if it is live at function entry. */
1631 regno_uninitialized (regno)
1634 if (n_basic_blocks == 0)
1637 return (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1638 & (1 << (regno % REGSET_ELT_BITS)));
1641 /* 1 if register REGNO was alive at a place where `setjmp' was called
1642 and was set more than once or is an argument.
1643 Such regs may be clobbered by `longjmp'. */
1646 regno_clobbered_at_setjmp (regno)
1649 if (n_basic_blocks == 0)
1652 return ((reg_n_sets[regno] > 1
1653 || (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
1654 & (1 << (regno % REGSET_ELT_BITS))))
1655 && (regs_live_at_setjmp[regno / REGSET_ELT_BITS]
1656 & (1 << (regno % REGSET_ELT_BITS))));
1659 /* Process the registers that are set within X.
1660 Their bits are set to 1 in the regset DEAD,
1661 because they are dead prior to this insn.
1663 If INSN is nonzero, it is the insn being processed
1664 and the fact that it is nonzero implies this is the FINAL pass
1665 in propagate_block. In this case, various info about register
1666 usage is stored, LOG_LINKS fields of insns are set up. */
1668 static void mark_set_1 ();
1671 mark_set_regs (needed, dead, x, insn, significant)
1678 register RTX_CODE code = GET_CODE (x);
1680 if (code == SET || code == CLOBBER)
1681 mark_set_1 (needed, dead, x, insn, significant);
1682 else if (code == PARALLEL)
1685 for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
1687 code = GET_CODE (XVECEXP (x, 0, i));
1688 if (code == SET || code == CLOBBER)
1689 mark_set_1 (needed, dead, XVECEXP (x, 0, i), insn, significant);
1694 /* Process a single SET rtx, X. */
1697 mark_set_1 (needed, dead, x, insn, significant)
1705 register rtx reg = SET_DEST (x);
1707 /* Modifying just one hardware register of a multi-reg value
1708 or just a byte field of a register
1709 does not mean the value from before this insn is now dead.
1710 But it does mean liveness of that register at the end of the block
1713 Within mark_set_1, however, we treat it as if the register is
1714 indeed modified. mark_used_regs will, however, also treat this
1715 register as being used. Thus, we treat these insns as setting a
1716 new value for the register as a function of its old value. This
1717 cases LOG_LINKS to be made appropriately and this will help combine. */
1719 while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
1720 || GET_CODE (reg) == SIGN_EXTRACT
1721 || GET_CODE (reg) == STRICT_LOW_PART)
1722 reg = XEXP (reg, 0);
1724 /* If we are writing into memory or into a register mentioned in the
1725 address of the last thing stored into memory, show we don't know
1726 what the last store was. If we are writing memory, save the address
1727 unless it is volatile. */
1728 if (GET_CODE (reg) == MEM
1729 || (GET_CODE (reg) == REG
1730 && last_mem_set != 0 && reg_overlap_mentioned_p (reg, last_mem_set)))
1733 if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
1734 /* There are no REG_INC notes for SP, so we can't assume we'll see
1735 everything that invalidates it. To be safe, don't eliminate any
1736 stores though SP; none of them should be redundant anyway. */
1737 && ! reg_mentioned_p (stack_pointer_rtx, reg))
1740 if (GET_CODE (reg) == REG
1741 && (regno = REGNO (reg), regno != FRAME_POINTER_REGNUM)
1742 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
1743 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
1745 && ! (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
1746 /* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
1748 register int offset = regno / REGSET_ELT_BITS;
1749 register int bit = 1 << (regno % REGSET_ELT_BITS);
1750 int all_needed = (needed[offset] & bit) != 0;
1751 int some_needed = (needed[offset] & bit) != 0;
1753 /* Mark it as a significant register for this basic block. */
1755 significant[offset] |= bit;
1757 /* Mark it as as dead before this insn. */
1758 dead[offset] |= bit;
1760 /* A hard reg in a wide mode may really be multiple registers.
1761 If so, mark all of them just like the first. */
1762 if (regno < FIRST_PSEUDO_REGISTER)
1766 /* Nothing below is needed for the stack pointer; get out asap.
1767 Eg, log links aren't needed, since combine won't use them. */
1768 if (regno == STACK_POINTER_REGNUM)
1771 n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
1775 significant[(regno + n) / REGSET_ELT_BITS]
1776 |= 1 << ((regno + n) % REGSET_ELT_BITS);
1777 dead[(regno + n) / REGSET_ELT_BITS]
1778 |= 1 << ((regno + n) % REGSET_ELT_BITS);
1779 some_needed |= (needed[(regno + n) / REGSET_ELT_BITS]
1780 & 1 << ((regno + n) % REGSET_ELT_BITS));
1781 all_needed &= (needed[(regno + n) / REGSET_ELT_BITS]
1782 & 1 << ((regno + n) % REGSET_ELT_BITS));
1785 /* Additional data to record if this is the final pass. */
1788 register rtx y = reg_next_use[regno];
1789 register int blocknum = BLOCK_NUM (insn);
1791 /* If this is a hard reg, record this function uses the reg. */
1793 if (regno < FIRST_PSEUDO_REGISTER)
1796 int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg));
1798 for (i = regno; i < endregno; i++)
1800 regs_ever_live[i] = 1;
1806 /* Keep track of which basic blocks each reg appears in. */
1808 if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
1809 reg_basic_block[regno] = blocknum;
1810 else if (reg_basic_block[regno] != blocknum)
1811 reg_basic_block[regno] = REG_BLOCK_GLOBAL;
1813 /* Count (weighted) references, stores, etc. This counts a
1814 register twice if it is modified, but that is correct. */
1815 reg_n_sets[regno]++;
1817 reg_n_refs[regno] += loop_depth;
1819 /* The insns where a reg is live are normally counted
1820 elsewhere, but we want the count to include the insn
1821 where the reg is set, and the normal counting mechanism
1822 would not count it. */
1823 reg_live_length[regno]++;
1826 /* The next use is no longer "next", since a store intervenes. */
1827 reg_next_use[regno] = 0;
1831 /* Make a logical link from the next following insn
1832 that uses this register, back to this insn.
1833 The following insns have already been processed.
1835 We don't build a LOG_LINK for hard registers containing
1836 in ASM_OPERANDs. If these registers get replaced,
1837 we might wind up changing the semantics of the insn,
1838 even if reload can make what appear to be valid assignments
1840 if (y && (BLOCK_NUM (y) == blocknum)
1841 && (regno >= FIRST_PSEUDO_REGISTER
1842 || asm_noperands (PATTERN (y)) < 0))
1844 = gen_rtx (INSN_LIST, VOIDmode, insn, LOG_LINKS (y));
1846 else if (! some_needed)
1848 /* Note that dead stores have already been deleted when possible
1849 If we get here, we have found a dead store that cannot
1850 be eliminated (because the same insn does something useful).
1851 Indicate this by marking the reg being set as dying here. */
1853 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
1854 reg_n_deaths[REGNO (reg)]++;
1858 /* This is a case where we have a multi-word hard register
1859 and some, but not all, of the words of the register are
1860 needed in subsequent insns. Write REG_UNUSED notes
1861 for those parts that were not needed. This case should
1866 for (i = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1;
1868 if ((needed[(regno + i) / REGSET_ELT_BITS]
1869 & 1 << ((regno + i) % REGSET_ELT_BITS)) == 0)
1871 = gen_rtx (EXPR_LIST, REG_UNUSED,
1872 gen_rtx (REG, word_mode, regno + i),
1878 /* If this is the last pass and this is a SCRATCH, show it will be dying
1879 here and count it. */
1880 else if (GET_CODE (reg) == SCRATCH && insn != 0)
1883 = gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
1890 /* X is a MEM found in INSN. See if we can convert it into an auto-increment
1894 find_auto_inc (needed, x, insn)
1899 rtx addr = XEXP (x, 0);
1902 /* Here we detect use of an index register which might be good for
1903 postincrement, postdecrement, preincrement, or predecrement. */
1905 if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
1906 offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
1908 if (GET_CODE (addr) == REG)
1911 register int size = GET_MODE_SIZE (GET_MODE (x));
1914 int regno = REGNO (addr);
1916 /* Is the next use an increment that might make auto-increment? */
1917 incr = reg_next_use[regno];
1918 if (incr && GET_CODE (PATTERN (incr)) == SET
1919 && BLOCK_NUM (incr) == BLOCK_NUM (insn)
1920 /* Can't add side effects to jumps; if reg is spilled and
1921 reloaded, there's no way to store back the altered value. */
1922 && GET_CODE (insn) != JUMP_INSN
1923 && (y = SET_SRC (PATTERN (incr)), GET_CODE (y) == PLUS)
1924 && XEXP (y, 0) == addr
1925 && GET_CODE (XEXP (y, 1)) == CONST_INT
1927 #ifdef HAVE_POST_INCREMENT
1928 || (INTVAL (XEXP (y, 1)) == size && offset == 0)
1930 #ifdef HAVE_POST_DECREMENT
1931 || (INTVAL (XEXP (y, 1)) == - size && offset == 0)
1933 #ifdef HAVE_PRE_INCREMENT
1934 || (INTVAL (XEXP (y, 1)) == size && offset == size)
1936 #ifdef HAVE_PRE_DECREMENT
1937 || (INTVAL (XEXP (y, 1)) == - size && offset == - size)
1940 /* Make sure this reg appears only once in this insn. */
1941 && (use = find_use_as_address (PATTERN (insn), addr, offset),
1942 use != 0 && use != (rtx) 1))
1945 rtx q = SET_DEST (PATTERN (incr));
1947 if (dead_or_set_p (incr, addr))
1949 else if (GET_CODE (q) == REG && ! reg_used_between_p (q, insn, incr))
1951 /* We have *p followed by q = p+size.
1952 Both p and q must be live afterward,
1953 and q must be dead before.
1954 Change it to q = p, ...*q..., q = q+size.
1955 Then fall into the usual case. */
1959 emit_move_insn (q, addr);
1960 insns = get_insns ();
1963 /* If anything in INSNS have UID's that don't fit within the
1964 extra space we allocate earlier, we can't make this auto-inc.
1965 This should never happen. */
1966 for (temp = insns; temp; temp = NEXT_INSN (temp))
1968 if (INSN_UID (temp) > max_uid_for_flow)
1970 BLOCK_NUM (temp) = BLOCK_NUM (insn);
1973 emit_insns_before (insns, insn);
1975 if (basic_block_head[BLOCK_NUM (insn)] == insn)
1976 basic_block_head[BLOCK_NUM (insn)] = insns;
1981 /* INCR will become a NOTE and INSN won't contain a
1982 use of ADDR. If a use of ADDR was just placed in
1983 the insn before INSN, make that the next use.
1984 Otherwise, invalidate it. */
1985 if (GET_CODE (PREV_INSN (insn)) == INSN
1986 && GET_CODE (PATTERN (PREV_INSN (insn))) == SET
1987 && SET_SRC (PATTERN (PREV_INSN (insn))) == addr)
1988 reg_next_use[regno] = PREV_INSN (insn);
1990 reg_next_use[regno] = 0;
1996 /* REGNO is now used in INCR which is below INSN, but
1997 it previously wasn't live here. If we don't mark
1998 it as needed, we'll put a REG_DEAD note for it
1999 on this insn, which is incorrect. */
2000 needed[regno / REGSET_ELT_BITS]
2001 |= 1 << (regno % REGSET_ELT_BITS);
2003 /* If there are any calls between INSN and INCR, show
2004 that REGNO now crosses them. */
2005 for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
2006 if (GET_CODE (temp) == CALL_INSN)
2007 reg_n_calls_crossed[regno]++;
2012 /* We have found a suitable auto-increment: do POST_INC around
2013 the register here, and patch out the increment instruction
2015 XEXP (x, 0) = gen_rtx ((INTVAL (XEXP (y, 1)) == size
2016 ? (offset ? PRE_INC : POST_INC)
2017 : (offset ? PRE_DEC : POST_DEC)),
2020 /* Record that this insn has an implicit side effect. */
2022 = gen_rtx (EXPR_LIST, REG_INC, addr, REG_NOTES (insn));
2024 /* Modify the old increment-insn to simply copy
2025 the already-incremented value of our register. */
2026 SET_SRC (PATTERN (incr)) = addr;
2027 /* Indicate insn must be re-recognized. */
2028 INSN_CODE (incr) = -1;
2030 /* If that makes it a no-op (copying the register into itself)
2031 then delete it so it won't appear to be a "use" and a "set"
2032 of this register. */
2033 if (SET_DEST (PATTERN (incr)) == addr)
2035 PUT_CODE (incr, NOTE);
2036 NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
2037 NOTE_SOURCE_FILE (incr) = 0;
2040 if (regno >= FIRST_PSEUDO_REGISTER)
2042 /* Count an extra reference to the reg. When a reg is
2043 incremented, spilling it is worse, so we want to make
2044 that less likely. */
2045 reg_n_refs[regno] += loop_depth;
2046 /* Count the increment as a setting of the register,
2047 even though it isn't a SET in rtl. */
2048 reg_n_sets[regno]++;
2054 #endif /* AUTO_INC_DEC */
2056 /* Scan expression X and store a 1-bit in LIVE for each reg it uses.
2057 This is done assuming the registers needed from X
2058 are those that have 1-bits in NEEDED.
2060 On the final pass, FINAL is 1. This means try for autoincrement
2061 and count the uses and deaths of each pseudo-reg.
2063 INSN is the containing instruction. If INSN is dead, this function is not
2067 mark_used_regs (needed, live, x, final, insn)
2074 register RTX_CODE code;
2079 code = GET_CODE (x);
2101 /* Invalidate the data for the last MEM stored. We could do this only
2102 if the addresses conflict, but this doesn't seem worthwhile. */
2107 find_auto_inc (needed, x, insn);
2112 /* See a register other than being set
2113 => mark it as needed. */
2117 register int offset = regno / REGSET_ELT_BITS;
2118 register int bit = 1 << (regno % REGSET_ELT_BITS);
2119 int all_needed = (needed[offset] & bit) != 0;
2120 int some_needed = (needed[offset] & bit) != 0;
2122 live[offset] |= bit;
2123 /* A hard reg in a wide mode may really be multiple registers.
2124 If so, mark all of them just like the first. */
2125 if (regno < FIRST_PSEUDO_REGISTER)
2129 /* For stack ptr or fixed arg pointer,
2130 nothing below can be necessary, so waste no more time. */
2131 if (regno == STACK_POINTER_REGNUM
2132 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2133 || (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2135 || regno == FRAME_POINTER_REGNUM)
2137 /* If this is a register we are going to try to eliminate,
2138 don't mark it live here. If we are successful in
2139 eliminating it, it need not be live unless it is used for
2140 pseudos, in which case it will have been set live when
2141 it was allocated to the pseudos. If the register will not
2142 be eliminated, reload will set it live at that point. */
2144 if (! TEST_HARD_REG_BIT (elim_reg_set, regno))
2145 regs_ever_live[regno] = 1;
2148 /* No death notes for global register variables;
2149 their values are live after this function exits. */
2150 if (global_regs[regno])
2153 n = HARD_REGNO_NREGS (regno, GET_MODE (x));
2156 live[(regno + n) / REGSET_ELT_BITS]
2157 |= 1 << ((regno + n) % REGSET_ELT_BITS);
2158 some_needed |= (needed[(regno + n) / REGSET_ELT_BITS]
2159 & 1 << ((regno + n) % REGSET_ELT_BITS));
2160 all_needed &= (needed[(regno + n) / REGSET_ELT_BITS]
2161 & 1 << ((regno + n) % REGSET_ELT_BITS));
2166 /* Record where each reg is used, so when the reg
2167 is set we know the next insn that uses it. */
2169 reg_next_use[regno] = insn;
2171 if (regno < FIRST_PSEUDO_REGISTER)
2173 /* If a hard reg is being used,
2174 record that this function does use it. */
2176 i = HARD_REGNO_NREGS (regno, GET_MODE (x));
2180 regs_ever_live[regno + --i] = 1;
2185 /* Keep track of which basic block each reg appears in. */
2187 register int blocknum = BLOCK_NUM (insn);
2189 if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
2190 reg_basic_block[regno] = blocknum;
2191 else if (reg_basic_block[regno] != blocknum)
2192 reg_basic_block[regno] = REG_BLOCK_GLOBAL;
2194 /* Count (weighted) number of uses of each reg. */
2196 reg_n_refs[regno] += loop_depth;
2199 /* Record and count the insns in which a reg dies.
2200 If it is used in this insn and was dead below the insn
2201 then it dies in this insn. If it was set in this insn,
2202 we do not make a REG_DEAD note; likewise if we already
2203 made such a note. */
2206 && ! dead_or_set_p (insn, x)
2208 && (regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
2212 /* If none of the words in X is needed, make a REG_DEAD
2213 note. Otherwise, we must make partial REG_DEAD notes. */
2217 = gen_rtx (EXPR_LIST, REG_DEAD, x, REG_NOTES (insn));
2218 reg_n_deaths[regno]++;
2224 /* Don't make a REG_DEAD note for a part of a register
2225 that is set in the insn. */
2227 for (i = HARD_REGNO_NREGS (regno, GET_MODE (x)) - 1;
2229 if ((needed[(regno + i) / REGSET_ELT_BITS]
2230 & 1 << ((regno + i) % REGSET_ELT_BITS)) == 0
2231 && ! dead_or_set_regno_p (insn, regno + i))
2233 = gen_rtx (EXPR_LIST, REG_DEAD,
2234 gen_rtx (REG, word_mode, regno + i),
2244 register rtx testreg = SET_DEST (x);
2247 /* If storing into MEM, don't show it as being used. But do
2248 show the address as being used. */
2249 if (GET_CODE (testreg) == MEM)
2253 find_auto_inc (needed, testreg, insn);
2255 mark_used_regs (needed, live, XEXP (testreg, 0), final, insn);
2256 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2260 /* Storing in STRICT_LOW_PART is like storing in a reg
2261 in that this SET might be dead, so ignore it in TESTREG.
2262 but in some other ways it is like using the reg.
2264 Storing in a SUBREG or a bit field is like storing the entire
2265 register in that if the register's value is not used
2266 then this SET is not needed. */
2267 while (GET_CODE (testreg) == STRICT_LOW_PART
2268 || GET_CODE (testreg) == ZERO_EXTRACT
2269 || GET_CODE (testreg) == SIGN_EXTRACT
2270 || GET_CODE (testreg) == SUBREG)
2272 /* Modifying a single register in an alternate mode
2273 does not use any of the old value. But these other
2274 ways of storing in a register do use the old value. */
2275 if (GET_CODE (testreg) == SUBREG
2276 && !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
2281 testreg = XEXP (testreg, 0);
2284 /* If this is a store into a register,
2285 recursively scan the value being stored. */
2287 if (GET_CODE (testreg) == REG
2288 && (regno = REGNO (testreg), regno != FRAME_POINTER_REGNUM)
2289 #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
2290 && ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
2292 && ! (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
2294 mark_used_regs (needed, live, SET_SRC (x), final, insn);
2296 mark_used_regs (needed, live, SET_DEST (x), final, insn);
2303 /* If exiting needs the right stack value, consider this insn as
2304 using the stack pointer. In any event, consider it as using
2305 all global registers. */
2307 #ifdef EXIT_IGNORE_STACK
2308 if (! EXIT_IGNORE_STACK
2309 || (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
2311 live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
2312 |= 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
2314 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2316 live[i / REGSET_ELT_BITS] |= 1 << (i % REGSET_ELT_BITS);
2320 /* Recursively scan the operands of this expression. */
2323 register char *fmt = GET_RTX_FORMAT (code);
2326 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2330 /* Tail recursive case: save a function call level. */
2336 mark_used_regs (needed, live, XEXP (x, i), final, insn);
2338 else if (fmt[i] == 'E')
2341 for (j = 0; j < XVECLEN (x, i); j++)
2342 mark_used_regs (needed, live, XVECEXP (x, i, j), final, insn);
2351 try_pre_increment_1 (insn)
2354 /* Find the next use of this reg. If in same basic block,
2355 make it do pre-increment or pre-decrement if appropriate. */
2356 rtx x = PATTERN (insn);
2357 int amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
2358 * INTVAL (XEXP (SET_SRC (x), 1)));
2359 int regno = REGNO (SET_DEST (x));
2360 rtx y = reg_next_use[regno];
2362 && BLOCK_NUM (y) == BLOCK_NUM (insn)
2363 && try_pre_increment (y, SET_DEST (PATTERN (insn)),
2366 /* We have found a suitable auto-increment
2367 and already changed insn Y to do it.
2368 So flush this increment-instruction. */
2369 PUT_CODE (insn, NOTE);
2370 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
2371 NOTE_SOURCE_FILE (insn) = 0;
2372 /* Count a reference to this reg for the increment
2373 insn we are deleting. When a reg is incremented.
2374 spilling it is worse, so we want to make that
2376 if (regno >= FIRST_PSEUDO_REGISTER)
2378 reg_n_refs[regno] += loop_depth;
2379 reg_n_sets[regno]++;
2386 /* Try to change INSN so that it does pre-increment or pre-decrement
2387 addressing on register REG in order to add AMOUNT to REG.
2388 AMOUNT is negative for pre-decrement.
2389 Returns 1 if the change could be made.
2390 This checks all about the validity of the result of modifying INSN. */
2393 try_pre_increment (insn, reg, amount)
2399 /* Nonzero if we can try to make a pre-increment or pre-decrement.
2400 For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
2402 /* Nonzero if we can try to make a post-increment or post-decrement.
2403 For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
2404 It is possible for both PRE_OK and POST_OK to be nonzero if the machine
2405 supports both pre-inc and post-inc, or both pre-dec and post-dec. */
2408 /* Nonzero if the opportunity actually requires post-inc or post-dec. */
2411 /* From the sign of increment, see which possibilities are conceivable
2412 on this target machine. */
2413 #ifdef HAVE_PRE_INCREMENT
2417 #ifdef HAVE_POST_INCREMENT
2422 #ifdef HAVE_PRE_DECREMENT
2426 #ifdef HAVE_POST_DECREMENT
2431 if (! (pre_ok || post_ok))
2434 /* It is not safe to add a side effect to a jump insn
2435 because if the incremented register is spilled and must be reloaded
2436 there would be no way to store the incremented value back in memory. */
2438 if (GET_CODE (insn) == JUMP_INSN)
2443 use = find_use_as_address (PATTERN (insn), reg, 0);
2444 if (post_ok && (use == 0 || use == (rtx) 1))
2446 use = find_use_as_address (PATTERN (insn), reg, -amount);
2450 if (use == 0 || use == (rtx) 1)
2453 if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
2456 XEXP (use, 0) = gen_rtx (amount > 0
2457 ? (do_post ? POST_INC : PRE_INC)
2458 : (do_post ? POST_DEC : PRE_DEC),
2461 /* Record that this insn now has an implicit side effect on X. */
2462 REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_INC, reg, REG_NOTES (insn));
2466 #endif /* AUTO_INC_DEC */
2468 /* Find the place in the rtx X where REG is used as a memory address.
2469 Return the MEM rtx that so uses it.
2470 If PLUSCONST is nonzero, search instead for a memory address equivalent to
2471 (plus REG (const_int PLUSCONST)).
2473 If such an address does not appear, return 0.
2474 If REG appears more than once, or is used other than in such an address,
2478 find_use_as_address (x, reg, plusconst)
2483 enum rtx_code code = GET_CODE (x);
2484 char *fmt = GET_RTX_FORMAT (code);
2486 register rtx value = 0;
2489 if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
2492 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
2493 && XEXP (XEXP (x, 0), 0) == reg
2494 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
2495 && INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
2498 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
2500 /* If REG occurs inside a MEM used in a bit-field reference,
2501 that is unacceptable. */
2502 if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
2509 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2513 tem = find_use_as_address (XEXP (x, i), reg, plusconst);
2522 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
2524 tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
2536 /* Write information about registers and basic blocks into FILE.
2537 This is part of making a debugging dump. */
2540 dump_flow_info (file)
2544 static char *reg_class_names[] = REG_CLASS_NAMES;
2546 fprintf (file, "%d registers.\n", max_regno);
2548 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
2551 enum reg_class class;
2552 fprintf (file, "\nRegister %d used %d times across %d insns",
2553 i, reg_n_refs[i], reg_live_length[i]);
2554 if (reg_basic_block[i] >= 0)
2555 fprintf (file, " in block %d", reg_basic_block[i]);
2556 if (reg_n_deaths[i] != 1)
2557 fprintf (file, "; dies in %d places", reg_n_deaths[i]);
2558 if (reg_n_calls_crossed[i] == 1)
2559 fprintf (file, "; crosses 1 call");
2560 else if (reg_n_calls_crossed[i])
2561 fprintf (file, "; crosses %d calls", reg_n_calls_crossed[i]);
2562 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
2563 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
2564 class = reg_preferred_class (i);
2565 if (class != GENERAL_REGS)
2567 if (reg_preferred_or_nothing (i))
2568 fprintf (file, "; %s or none", reg_class_names[(int) class]);
2570 fprintf (file, "; pref %s", reg_class_names[(int) class]);
2572 if (REGNO_POINTER_FLAG (i))
2573 fprintf (file, "; pointer");
2574 fprintf (file, ".\n");
2576 fprintf (file, "\n%d basic blocks.\n", n_basic_blocks);
2577 for (i = 0; i < n_basic_blocks; i++)
2579 register rtx head, jump;
2581 fprintf (file, "\nBasic block %d: first insn %d, last %d.\n",
2583 INSN_UID (basic_block_head[i]),
2584 INSN_UID (basic_block_end[i]));
2585 /* The control flow graph's storage is freed
2586 now when flow_analysis returns.
2587 Don't try to print it if it is gone. */
2588 if (basic_block_drops_in)
2590 fprintf (file, "Reached from blocks: ");
2591 head = basic_block_head[i];
2592 if (GET_CODE (head) == CODE_LABEL)
2593 for (jump = LABEL_REFS (head);
2595 jump = LABEL_NEXTREF (jump))
2597 register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
2598 fprintf (file, " %d", from_block);
2600 if (basic_block_drops_in[i])
2601 fprintf (file, " previous");
2603 fprintf (file, "\nRegisters live at start:");
2604 for (regno = 0; regno < max_regno; regno++)
2606 register int offset = regno / REGSET_ELT_BITS;
2607 register int bit = 1 << (regno % REGSET_ELT_BITS);
2608 if (basic_block_live_at_start[i][offset] & bit)
2609 fprintf (file, " %d", regno);
2611 fprintf (file, "\n");
2613 fprintf (file, "\n");