2013-08-02 Paolo Carlini <paolo.carlini@oracle.com>
[official-gcc.git] / gcc / auto-inc-dec.c
blob6119bb6e75745aeb1b874f3c2cc61e95090de68b
1 /* Discovery of auto-inc and auto-dec instructions.
2 Copyright (C) 2006-2013 Free Software Foundation, Inc.
3 Contributed by Kenneth Zadeck <zadeck@naturalbridge.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
10 version.
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
21 #include "config.h"
22 #include "system.h"
23 #include "coretypes.h"
24 #include "tm.h"
25 #include "tree.h"
26 #include "rtl.h"
27 #include "tm_p.h"
28 #include "hard-reg-set.h"
29 #include "basic-block.h"
30 #include "insn-config.h"
31 #include "regs.h"
32 #include "flags.h"
33 #include "function.h"
34 #include "except.h"
35 #include "diagnostic-core.h"
36 #include "recog.h"
37 #include "expr.h"
38 #include "tree-pass.h"
39 #include "df.h"
40 #include "dbgcnt.h"
41 #include "target.h"
43 /* This pass was originally removed from flow.c. However there is
44 almost nothing that remains of that code.
46 There are (4) basic forms that are matched:
48 (1) FORM_PRE_ADD
49 a <- b + c
50 ...
53 becomes
55 a <- b
56 ...
57 *(a += c) pre
60 (2) FORM_PRE_INC
61 a += c
62 ...
65 becomes
67 *(a += c) pre
70 (3) FORM_POST_ADD
72 ...
73 b <- a + c
75 (For this case to be true, b must not be assigned or used between
76 the *a and the assignment to b. B must also be a Pmode reg.)
78 becomes
80 b <- a
81 ...
82 *(b += c) post
85 (4) FORM_POST_INC
87 ...
88 a <- a + c
90 becomes
92 *(a += c) post
94 There are three types of values of c.
96 1) c is a constant equal to the width of the value being accessed by
97 the pointer. This is useful for machines that have
98 HAVE_PRE_INCREMENT, HAVE_POST_INCREMENT, HAVE_PRE_DECREMENT or
99 HAVE_POST_DECREMENT defined.
101 2) c is a constant not equal to the width of the value being accessed
102 by the pointer. This is useful for machines that have
103 HAVE_PRE_MODIFY_DISP, HAVE_POST_MODIFY_DISP defined.
105 3) c is a register. This is useful for machines that have
106 HAVE_PRE_MODIFY_REG, HAVE_POST_MODIFY_REG
108 The is one special case: if a already had an offset equal to it +-
109 its width and that offset is equal to -c when the increment was
110 before the ref or +c if the increment was after the ref, then if we
111 can do the combination but switch the pre/post bit. */
113 #ifdef AUTO_INC_DEC
115 enum form
117 FORM_PRE_ADD,
118 FORM_PRE_INC,
119 FORM_POST_ADD,
120 FORM_POST_INC,
121 FORM_last
124 /* The states of the second operands of mem refs and inc insns. If no
125 second operand of the mem_ref was found, it is assumed to just be
126 ZERO. SIZE is the size of the mode accessed in the memref. The
127 ANY is used for constants that are not +-size or 0. REG is used if
128 the forms are reg1 + reg2. */
130 enum inc_state
132 INC_ZERO, /* == 0 */
133 INC_NEG_SIZE, /* == +size */
134 INC_POS_SIZE, /* == -size */
135 INC_NEG_ANY, /* == some -constant */
136 INC_POS_ANY, /* == some +constant */
137 INC_REG, /* == some register */
138 INC_last
141 /* The eight forms that pre/post inc/dec can take. */
142 enum gen_form
144 NOTHING,
145 SIMPLE_PRE_INC, /* ++size */
146 SIMPLE_POST_INC, /* size++ */
147 SIMPLE_PRE_DEC, /* --size */
148 SIMPLE_POST_DEC, /* size-- */
149 DISP_PRE, /* ++con */
150 DISP_POST, /* con++ */
151 REG_PRE, /* ++reg */
152 REG_POST /* reg++ */
155 /* Tmp mem rtx for use in cost modeling. */
156 static rtx mem_tmp;
158 static enum inc_state
159 set_inc_state (HOST_WIDE_INT val, int size)
161 if (val == 0)
162 return INC_ZERO;
163 if (val < 0)
164 return (val == -size) ? INC_NEG_SIZE : INC_NEG_ANY;
165 else
166 return (val == size) ? INC_POS_SIZE : INC_POS_ANY;
169 /* The DECISION_TABLE that describes what form, if any, the increment
170 or decrement will take. It is a three dimensional table. The first
171 index is the type of constant or register found as the second
172 operand of the inc insn. The second index is the type of constant
173 or register found as the second operand of the memory reference (if
174 no second operand exists, 0 is used). The third index is the form
175 and location (relative to the mem reference) of inc insn. */
177 static bool initialized = false;
178 static enum gen_form decision_table[INC_last][INC_last][FORM_last];
180 static void
181 init_decision_table (void)
183 enum gen_form value;
185 if (HAVE_PRE_INCREMENT || HAVE_PRE_MODIFY_DISP)
187 /* Prefer the simple form if both are available. */
188 value = (HAVE_PRE_INCREMENT) ? SIMPLE_PRE_INC : DISP_PRE;
190 decision_table[INC_POS_SIZE][INC_ZERO][FORM_PRE_ADD] = value;
191 decision_table[INC_POS_SIZE][INC_ZERO][FORM_PRE_INC] = value;
193 decision_table[INC_POS_SIZE][INC_POS_SIZE][FORM_POST_ADD] = value;
194 decision_table[INC_POS_SIZE][INC_POS_SIZE][FORM_POST_INC] = value;
197 if (HAVE_POST_INCREMENT || HAVE_POST_MODIFY_DISP)
199 /* Prefer the simple form if both are available. */
200 value = (HAVE_POST_INCREMENT) ? SIMPLE_POST_INC : DISP_POST;
202 decision_table[INC_POS_SIZE][INC_ZERO][FORM_POST_ADD] = value;
203 decision_table[INC_POS_SIZE][INC_ZERO][FORM_POST_INC] = value;
205 decision_table[INC_POS_SIZE][INC_NEG_SIZE][FORM_PRE_ADD] = value;
206 decision_table[INC_POS_SIZE][INC_NEG_SIZE][FORM_PRE_INC] = value;
209 if (HAVE_PRE_DECREMENT || HAVE_PRE_MODIFY_DISP)
211 /* Prefer the simple form if both are available. */
212 value = (HAVE_PRE_DECREMENT) ? SIMPLE_PRE_DEC : DISP_PRE;
214 decision_table[INC_NEG_SIZE][INC_ZERO][FORM_PRE_ADD] = value;
215 decision_table[INC_NEG_SIZE][INC_ZERO][FORM_PRE_INC] = value;
217 decision_table[INC_NEG_SIZE][INC_NEG_SIZE][FORM_POST_ADD] = value;
218 decision_table[INC_NEG_SIZE][INC_NEG_SIZE][FORM_POST_INC] = value;
221 if (HAVE_POST_DECREMENT || HAVE_POST_MODIFY_DISP)
223 /* Prefer the simple form if both are available. */
224 value = (HAVE_POST_DECREMENT) ? SIMPLE_POST_DEC : DISP_POST;
226 decision_table[INC_NEG_SIZE][INC_ZERO][FORM_POST_ADD] = value;
227 decision_table[INC_NEG_SIZE][INC_ZERO][FORM_POST_INC] = value;
229 decision_table[INC_NEG_SIZE][INC_POS_SIZE][FORM_PRE_ADD] = value;
230 decision_table[INC_NEG_SIZE][INC_POS_SIZE][FORM_PRE_INC] = value;
233 if (HAVE_PRE_MODIFY_DISP)
235 decision_table[INC_POS_ANY][INC_ZERO][FORM_PRE_ADD] = DISP_PRE;
236 decision_table[INC_POS_ANY][INC_ZERO][FORM_PRE_INC] = DISP_PRE;
238 decision_table[INC_POS_ANY][INC_POS_ANY][FORM_POST_ADD] = DISP_PRE;
239 decision_table[INC_POS_ANY][INC_POS_ANY][FORM_POST_INC] = DISP_PRE;
241 decision_table[INC_NEG_ANY][INC_ZERO][FORM_PRE_ADD] = DISP_PRE;
242 decision_table[INC_NEG_ANY][INC_ZERO][FORM_PRE_INC] = DISP_PRE;
244 decision_table[INC_NEG_ANY][INC_NEG_ANY][FORM_POST_ADD] = DISP_PRE;
245 decision_table[INC_NEG_ANY][INC_NEG_ANY][FORM_POST_INC] = DISP_PRE;
248 if (HAVE_POST_MODIFY_DISP)
250 decision_table[INC_POS_ANY][INC_ZERO][FORM_POST_ADD] = DISP_POST;
251 decision_table[INC_POS_ANY][INC_ZERO][FORM_POST_INC] = DISP_POST;
253 decision_table[INC_POS_ANY][INC_NEG_ANY][FORM_PRE_ADD] = DISP_POST;
254 decision_table[INC_POS_ANY][INC_NEG_ANY][FORM_PRE_INC] = DISP_POST;
256 decision_table[INC_NEG_ANY][INC_ZERO][FORM_POST_ADD] = DISP_POST;
257 decision_table[INC_NEG_ANY][INC_ZERO][FORM_POST_INC] = DISP_POST;
259 decision_table[INC_NEG_ANY][INC_POS_ANY][FORM_PRE_ADD] = DISP_POST;
260 decision_table[INC_NEG_ANY][INC_POS_ANY][FORM_PRE_INC] = DISP_POST;
263 /* This is much simpler than the other cases because we do not look
264 for the reg1-reg2 case. Note that we do not have a INC_POS_REG
265 and INC_NEG_REG states. Most of the use of such states would be
266 on a target that had an R1 - R2 update address form.
268 There is the remote possibility that you could also catch a = a +
269 b; *(a - b) as a postdecrement of (a + b). However, it is
270 unclear if *(a - b) would ever be generated on a machine that did
271 not have that kind of addressing mode. The IA-64 and RS6000 will
272 not do this, and I cannot speak for any other. If any
273 architecture does have an a-b update for, these cases should be
274 added. */
275 if (HAVE_PRE_MODIFY_REG)
277 decision_table[INC_REG][INC_ZERO][FORM_PRE_ADD] = REG_PRE;
278 decision_table[INC_REG][INC_ZERO][FORM_PRE_INC] = REG_PRE;
280 decision_table[INC_REG][INC_REG][FORM_POST_ADD] = REG_PRE;
281 decision_table[INC_REG][INC_REG][FORM_POST_INC] = REG_PRE;
284 if (HAVE_POST_MODIFY_REG)
286 decision_table[INC_REG][INC_ZERO][FORM_POST_ADD] = REG_POST;
287 decision_table[INC_REG][INC_ZERO][FORM_POST_INC] = REG_POST;
290 initialized = true;
293 /* Parsed fields of an inc insn of the form "reg_res = reg0+reg1" or
294 "reg_res = reg0+c". */
296 static struct inc_insn
298 rtx insn; /* The insn being parsed. */
299 rtx pat; /* The pattern of the insn. */
300 bool reg1_is_const; /* True if reg1 is const, false if reg1 is a reg. */
301 enum form form;
302 rtx reg_res;
303 rtx reg0;
304 rtx reg1;
305 enum inc_state reg1_state;/* The form of the const if reg1 is a const. */
306 HOST_WIDE_INT reg1_val;/* Value if reg1 is const. */
307 } inc_insn;
310 /* Dump the parsed inc insn to FILE. */
312 static void
313 dump_inc_insn (FILE *file)
315 const char *f = ((inc_insn.form == FORM_PRE_ADD)
316 || (inc_insn.form == FORM_PRE_INC)) ? "pre" : "post";
318 dump_insn_slim (file, inc_insn.insn);
320 switch (inc_insn.form)
322 case FORM_PRE_ADD:
323 case FORM_POST_ADD:
324 if (inc_insn.reg1_is_const)
325 fprintf (file, "found %s add(%d) r[%d]=r[%d]+%d\n",
326 f, INSN_UID (inc_insn.insn),
327 REGNO (inc_insn.reg_res),
328 REGNO (inc_insn.reg0), (int) inc_insn.reg1_val);
329 else
330 fprintf (file, "found %s add(%d) r[%d]=r[%d]+r[%d]\n",
331 f, INSN_UID (inc_insn.insn),
332 REGNO (inc_insn.reg_res),
333 REGNO (inc_insn.reg0), REGNO (inc_insn.reg1));
334 break;
336 case FORM_PRE_INC:
337 case FORM_POST_INC:
338 if (inc_insn.reg1_is_const)
339 fprintf (file, "found %s inc(%d) r[%d]+=%d\n",
340 f, INSN_UID (inc_insn.insn),
341 REGNO (inc_insn.reg_res), (int) inc_insn.reg1_val);
342 else
343 fprintf (file, "found %s inc(%d) r[%d]+=r[%d]\n",
344 f, INSN_UID (inc_insn.insn),
345 REGNO (inc_insn.reg_res), REGNO (inc_insn.reg1));
346 break;
348 default:
349 break;
354 /* Parsed fields of a mem ref of the form "*(reg0+reg1)" or "*(reg0+c)". */
356 static struct mem_insn
358 rtx insn; /* The insn being parsed. */
359 rtx pat; /* The pattern of the insn. */
360 rtx *mem_loc; /* The address of the field that holds the mem */
361 /* that is to be replaced. */
362 bool reg1_is_const; /* True if reg1 is const, false if reg1 is a reg. */
363 rtx reg0;
364 rtx reg1; /* This is either a reg or a const depending on
365 reg1_is_const. */
366 enum inc_state reg1_state;/* The form of the const if reg1 is a const. */
367 HOST_WIDE_INT reg1_val;/* Value if reg1 is const. */
368 } mem_insn;
371 /* Dump the parsed mem insn to FILE. */
373 static void
374 dump_mem_insn (FILE *file)
376 dump_insn_slim (file, mem_insn.insn);
378 if (mem_insn.reg1_is_const)
379 fprintf (file, "found mem(%d) *(r[%d]+%d)\n",
380 INSN_UID (mem_insn.insn),
381 REGNO (mem_insn.reg0), (int) mem_insn.reg1_val);
382 else
383 fprintf (file, "found mem(%d) *(r[%d]+r[%d])\n",
384 INSN_UID (mem_insn.insn),
385 REGNO (mem_insn.reg0), REGNO (mem_insn.reg1));
389 /* The following three arrays contain pointers to instructions. They
390 are indexed by REGNO. At any point in the basic block where we are
391 looking these three arrays contain, respectively, the next insn
392 that uses REGNO, the next inc or add insn that uses REGNO and the
393 next insn that sets REGNO.
395 The arrays are not cleared when we move from block to block so
396 whenever an insn is retrieved from these arrays, it's block number
397 must be compared with the current block.
400 static rtx *reg_next_use = NULL;
401 static rtx *reg_next_inc_use = NULL;
402 static rtx *reg_next_def = NULL;
405 /* Move dead note that match PATTERN to TO_INSN from FROM_INSN. We do
406 not really care about moving any other notes from the inc or add
407 insn. Moving the REG_EQUAL and REG_EQUIV is clearly wrong and it
408 does not appear that there are any other kinds of relevant notes. */
410 static void
411 move_dead_notes (rtx to_insn, rtx from_insn, rtx pattern)
413 rtx note;
414 rtx next_note;
415 rtx prev_note = NULL;
417 for (note = REG_NOTES (from_insn); note; note = next_note)
419 next_note = XEXP (note, 1);
421 if ((REG_NOTE_KIND (note) == REG_DEAD)
422 && pattern == XEXP (note, 0))
424 XEXP (note, 1) = REG_NOTES (to_insn);
425 REG_NOTES (to_insn) = note;
426 if (prev_note)
427 XEXP (prev_note, 1) = next_note;
428 else
429 REG_NOTES (from_insn) = next_note;
431 else prev_note = note;
436 /* Create a mov insn DEST_REG <- SRC_REG and insert it before
437 NEXT_INSN. */
439 static rtx
440 insert_move_insn_before (rtx next_insn, rtx dest_reg, rtx src_reg)
442 rtx insns;
444 start_sequence ();
445 emit_move_insn (dest_reg, src_reg);
446 insns = get_insns ();
447 end_sequence ();
448 emit_insn_before (insns, next_insn);
449 return insns;
453 /* Change mem_insn.mem_loc so that uses NEW_ADDR which has an
454 increment of INC_REG. To have reached this point, the change is a
455 legitimate one from a dataflow point of view. The only questions
456 are is this a valid change to the instruction and is this a
457 profitable change to the instruction. */
459 static bool
460 attempt_change (rtx new_addr, rtx inc_reg)
462 /* There are four cases: For the two cases that involve an add
463 instruction, we are going to have to delete the add and insert a
464 mov. We are going to assume that the mov is free. This is
465 fairly early in the backend and there are a lot of opportunities
466 for removing that move later. In particular, there is the case
467 where the move may be dead, this is what dead code elimination
468 passes are for. The two cases where we have an inc insn will be
469 handled mov free. */
471 basic_block bb = BLOCK_FOR_INSN (mem_insn.insn);
472 rtx mov_insn = NULL;
473 int regno;
474 rtx mem = *mem_insn.mem_loc;
475 enum machine_mode mode = GET_MODE (mem);
476 rtx new_mem;
477 int old_cost = 0;
478 int new_cost = 0;
479 bool speed = optimize_bb_for_speed_p (bb);
481 PUT_MODE (mem_tmp, mode);
482 XEXP (mem_tmp, 0) = new_addr;
484 old_cost = (set_src_cost (mem, speed)
485 + set_rtx_cost (PATTERN (inc_insn.insn), speed));
486 new_cost = set_src_cost (mem_tmp, speed);
488 /* The first item of business is to see if this is profitable. */
489 if (old_cost < new_cost)
491 if (dump_file)
492 fprintf (dump_file, "cost failure old=%d new=%d\n", old_cost, new_cost);
493 return false;
496 /* Jump through a lot of hoops to keep the attributes up to date. We
497 do not want to call one of the change address variants that take
498 an offset even though we know the offset in many cases. These
499 assume you are changing where the address is pointing by the
500 offset. */
501 new_mem = replace_equiv_address_nv (mem, new_addr);
502 if (! validate_change (mem_insn.insn, mem_insn.mem_loc, new_mem, 0))
504 if (dump_file)
505 fprintf (dump_file, "validation failure\n");
506 return false;
509 /* From here to the end of the function we are committed to the
510 change, i.e. nothing fails. Generate any necessary movs, move
511 any regnotes, and fix up the reg_next_{use,inc_use,def}. */
512 switch (inc_insn.form)
514 case FORM_PRE_ADD:
515 /* Replace the addition with a move. Do it at the location of
516 the addition since the operand of the addition may change
517 before the memory reference. */
518 mov_insn = insert_move_insn_before (inc_insn.insn,
519 inc_insn.reg_res, inc_insn.reg0);
520 move_dead_notes (mov_insn, inc_insn.insn, inc_insn.reg0);
522 regno = REGNO (inc_insn.reg_res);
523 reg_next_def[regno] = mov_insn;
524 reg_next_use[regno] = NULL;
525 regno = REGNO (inc_insn.reg0);
526 reg_next_use[regno] = mov_insn;
527 df_recompute_luids (bb);
528 break;
530 case FORM_POST_INC:
531 regno = REGNO (inc_insn.reg_res);
532 if (reg_next_use[regno] == reg_next_inc_use[regno])
533 reg_next_inc_use[regno] = NULL;
535 /* Fallthru. */
536 case FORM_PRE_INC:
537 regno = REGNO (inc_insn.reg_res);
538 reg_next_def[regno] = mem_insn.insn;
539 reg_next_use[regno] = NULL;
541 break;
543 case FORM_POST_ADD:
544 mov_insn = insert_move_insn_before (mem_insn.insn,
545 inc_insn.reg_res, inc_insn.reg0);
546 move_dead_notes (mov_insn, inc_insn.insn, inc_insn.reg0);
548 /* Do not move anything to the mov insn because the instruction
549 pointer for the main iteration has not yet hit that. It is
550 still pointing to the mem insn. */
551 regno = REGNO (inc_insn.reg_res);
552 reg_next_def[regno] = mem_insn.insn;
553 reg_next_use[regno] = NULL;
555 regno = REGNO (inc_insn.reg0);
556 reg_next_use[regno] = mem_insn.insn;
557 if ((reg_next_use[regno] == reg_next_inc_use[regno])
558 || (reg_next_inc_use[regno] == inc_insn.insn))
559 reg_next_inc_use[regno] = NULL;
560 df_recompute_luids (bb);
561 break;
563 case FORM_last:
564 default:
565 gcc_unreachable ();
568 if (!inc_insn.reg1_is_const)
570 regno = REGNO (inc_insn.reg1);
571 reg_next_use[regno] = mem_insn.insn;
572 if ((reg_next_use[regno] == reg_next_inc_use[regno])
573 || (reg_next_inc_use[regno] == inc_insn.insn))
574 reg_next_inc_use[regno] = NULL;
577 delete_insn (inc_insn.insn);
579 if (dump_file && mov_insn)
581 fprintf (dump_file, "inserting mov ");
582 dump_insn_slim (dump_file, mov_insn);
585 /* Record that this insn has an implicit side effect. */
586 add_reg_note (mem_insn.insn, REG_INC, inc_reg);
588 if (dump_file)
590 fprintf (dump_file, "****success ");
591 dump_insn_slim (dump_file, mem_insn.insn);
594 return true;
598 /* Try to combine the instruction in INC_INSN with the instruction in
599 MEM_INSN. First the form is determined using the DECISION_TABLE
600 and the results of parsing the INC_INSN and the MEM_INSN.
601 Assuming the form is ok, a prototype new address is built which is
602 passed to ATTEMPT_CHANGE for final processing. */
604 static bool
605 try_merge (void)
607 enum gen_form gen_form;
608 rtx mem = *mem_insn.mem_loc;
609 rtx inc_reg = inc_insn.form == FORM_POST_ADD ?
610 inc_insn.reg_res : mem_insn.reg0;
612 /* The width of the mem being accessed. */
613 int size = GET_MODE_SIZE (GET_MODE (mem));
614 rtx last_insn = NULL;
615 enum machine_mode reg_mode = GET_MODE (inc_reg);
617 switch (inc_insn.form)
619 case FORM_PRE_ADD:
620 case FORM_PRE_INC:
621 last_insn = mem_insn.insn;
622 break;
623 case FORM_POST_INC:
624 case FORM_POST_ADD:
625 last_insn = inc_insn.insn;
626 break;
627 case FORM_last:
628 default:
629 gcc_unreachable ();
632 /* Cannot handle auto inc of the stack. */
633 if (inc_reg == stack_pointer_rtx)
635 if (dump_file)
636 fprintf (dump_file, "cannot inc stack %d failure\n", REGNO (inc_reg));
637 return false;
640 /* Look to see if the inc register is dead after the memory
641 reference. If it is, do not do the combination. */
642 if (find_regno_note (last_insn, REG_DEAD, REGNO (inc_reg)))
644 if (dump_file)
645 fprintf (dump_file, "dead failure %d\n", REGNO (inc_reg));
646 return false;
649 mem_insn.reg1_state = (mem_insn.reg1_is_const)
650 ? set_inc_state (mem_insn.reg1_val, size) : INC_REG;
651 inc_insn.reg1_state = (inc_insn.reg1_is_const)
652 ? set_inc_state (inc_insn.reg1_val, size) : INC_REG;
654 /* Now get the form that we are generating. */
655 gen_form = decision_table
656 [inc_insn.reg1_state][mem_insn.reg1_state][inc_insn.form];
658 if (dbg_cnt (auto_inc_dec) == false)
659 return false;
661 switch (gen_form)
663 default:
664 case NOTHING:
665 return false;
667 case SIMPLE_PRE_INC: /* ++size */
668 if (dump_file)
669 fprintf (dump_file, "trying SIMPLE_PRE_INC\n");
670 return attempt_change (gen_rtx_PRE_INC (reg_mode, inc_reg), inc_reg);
671 break;
673 case SIMPLE_POST_INC: /* size++ */
674 if (dump_file)
675 fprintf (dump_file, "trying SIMPLE_POST_INC\n");
676 return attempt_change (gen_rtx_POST_INC (reg_mode, inc_reg), inc_reg);
677 break;
679 case SIMPLE_PRE_DEC: /* --size */
680 if (dump_file)
681 fprintf (dump_file, "trying SIMPLE_PRE_DEC\n");
682 return attempt_change (gen_rtx_PRE_DEC (reg_mode, inc_reg), inc_reg);
683 break;
685 case SIMPLE_POST_DEC: /* size-- */
686 if (dump_file)
687 fprintf (dump_file, "trying SIMPLE_POST_DEC\n");
688 return attempt_change (gen_rtx_POST_DEC (reg_mode, inc_reg), inc_reg);
689 break;
691 case DISP_PRE: /* ++con */
692 if (dump_file)
693 fprintf (dump_file, "trying DISP_PRE\n");
694 return attempt_change (gen_rtx_PRE_MODIFY (reg_mode,
695 inc_reg,
696 gen_rtx_PLUS (reg_mode,
697 inc_reg,
698 inc_insn.reg1)),
699 inc_reg);
700 break;
702 case DISP_POST: /* con++ */
703 if (dump_file)
704 fprintf (dump_file, "trying POST_DISP\n");
705 return attempt_change (gen_rtx_POST_MODIFY (reg_mode,
706 inc_reg,
707 gen_rtx_PLUS (reg_mode,
708 inc_reg,
709 inc_insn.reg1)),
710 inc_reg);
711 break;
713 case REG_PRE: /* ++reg */
714 if (dump_file)
715 fprintf (dump_file, "trying PRE_REG\n");
716 return attempt_change (gen_rtx_PRE_MODIFY (reg_mode,
717 inc_reg,
718 gen_rtx_PLUS (reg_mode,
719 inc_reg,
720 inc_insn.reg1)),
721 inc_reg);
722 break;
724 case REG_POST: /* reg++ */
725 if (dump_file)
726 fprintf (dump_file, "trying POST_REG\n");
727 return attempt_change (gen_rtx_POST_MODIFY (reg_mode,
728 inc_reg,
729 gen_rtx_PLUS (reg_mode,
730 inc_reg,
731 inc_insn.reg1)),
732 inc_reg);
733 break;
737 /* Return the next insn that uses (if reg_next_use is passed in
738 NEXT_ARRAY) or defines (if reg_next_def is passed in NEXT_ARRAY)
739 REGNO in BB. */
741 static rtx
742 get_next_ref (int regno, basic_block bb, rtx *next_array)
744 rtx insn = next_array[regno];
746 /* Lazy about cleaning out the next_arrays. */
747 if (insn && BLOCK_FOR_INSN (insn) != bb)
749 next_array[regno] = NULL;
750 insn = NULL;
753 return insn;
757 /* Reverse the operands in a mem insn. */
759 static void
760 reverse_mem (void)
762 rtx tmp = mem_insn.reg1;
763 mem_insn.reg1 = mem_insn.reg0;
764 mem_insn.reg0 = tmp;
768 /* Reverse the operands in a inc insn. */
770 static void
771 reverse_inc (void)
773 rtx tmp = inc_insn.reg1;
774 inc_insn.reg1 = inc_insn.reg0;
775 inc_insn.reg0 = tmp;
779 /* Return true if INSN is of a form "a = b op c" where a and b are
780 regs. op is + if c is a reg and +|- if c is a const. Fill in
781 INC_INSN with what is found.
783 This function is called in two contexts, if BEFORE_MEM is true,
784 this is called for each insn in the basic block. If BEFORE_MEM is
785 false, it is called for the instruction in the block that uses the
786 index register for some memory reference that is currently being
787 processed. */
789 static bool
790 parse_add_or_inc (rtx insn, bool before_mem)
792 rtx pat = single_set (insn);
793 if (!pat)
794 return false;
796 /* Result must be single reg. */
797 if (!REG_P (SET_DEST (pat)))
798 return false;
800 if ((GET_CODE (SET_SRC (pat)) != PLUS)
801 && (GET_CODE (SET_SRC (pat)) != MINUS))
802 return false;
804 if (!REG_P (XEXP (SET_SRC (pat), 0)))
805 return false;
807 inc_insn.insn = insn;
808 inc_insn.pat = pat;
809 inc_insn.reg_res = SET_DEST (pat);
810 inc_insn.reg0 = XEXP (SET_SRC (pat), 0);
811 if (rtx_equal_p (inc_insn.reg_res, inc_insn.reg0))
812 inc_insn.form = before_mem ? FORM_PRE_INC : FORM_POST_INC;
813 else
814 inc_insn.form = before_mem ? FORM_PRE_ADD : FORM_POST_ADD;
816 if (CONST_INT_P (XEXP (SET_SRC (pat), 1)))
818 /* Process a = b + c where c is a const. */
819 inc_insn.reg1_is_const = true;
820 if (GET_CODE (SET_SRC (pat)) == PLUS)
822 inc_insn.reg1 = XEXP (SET_SRC (pat), 1);
823 inc_insn.reg1_val = INTVAL (inc_insn.reg1);
825 else
827 inc_insn.reg1_val = -INTVAL (XEXP (SET_SRC (pat), 1));
828 inc_insn.reg1 = GEN_INT (inc_insn.reg1_val);
830 return true;
832 else if ((HAVE_PRE_MODIFY_REG || HAVE_POST_MODIFY_REG)
833 && (REG_P (XEXP (SET_SRC (pat), 1)))
834 && GET_CODE (SET_SRC (pat)) == PLUS)
836 /* Process a = b + c where c is a reg. */
837 inc_insn.reg1 = XEXP (SET_SRC (pat), 1);
838 inc_insn.reg1_is_const = false;
840 if (inc_insn.form == FORM_PRE_INC
841 || inc_insn.form == FORM_POST_INC)
842 return true;
843 else if (rtx_equal_p (inc_insn.reg_res, inc_insn.reg1))
845 /* Reverse the two operands and turn *_ADD into *_INC since
846 a = c + a. */
847 reverse_inc ();
848 inc_insn.form = before_mem ? FORM_PRE_INC : FORM_POST_INC;
849 return true;
851 else
852 return true;
855 return false;
859 /* A recursive function that checks all of the mem uses in
860 ADDRESS_OF_X to see if any single one of them is compatible with
861 what has been found in inc_insn.
863 -1 is returned for success. 0 is returned if nothing was found and
864 1 is returned for failure. */
866 static int
867 find_address (rtx *address_of_x)
869 rtx x = *address_of_x;
870 enum rtx_code code = GET_CODE (x);
871 const char *const fmt = GET_RTX_FORMAT (code);
872 int i;
873 int value = 0;
874 int tem;
876 if (code == MEM && rtx_equal_p (XEXP (x, 0), inc_insn.reg_res))
878 /* Match with *reg0. */
879 mem_insn.mem_loc = address_of_x;
880 mem_insn.reg0 = inc_insn.reg_res;
881 mem_insn.reg1_is_const = true;
882 mem_insn.reg1_val = 0;
883 mem_insn.reg1 = GEN_INT (0);
884 return -1;
886 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
887 && rtx_equal_p (XEXP (XEXP (x, 0), 0), inc_insn.reg_res))
889 rtx b = XEXP (XEXP (x, 0), 1);
890 mem_insn.mem_loc = address_of_x;
891 mem_insn.reg0 = inc_insn.reg_res;
892 mem_insn.reg1 = b;
893 mem_insn.reg1_is_const = inc_insn.reg1_is_const;
894 if (CONST_INT_P (b))
896 /* Match with *(reg0 + reg1) where reg1 is a const. */
897 HOST_WIDE_INT val = INTVAL (b);
898 if (inc_insn.reg1_is_const
899 && (inc_insn.reg1_val == val || inc_insn.reg1_val == -val))
901 mem_insn.reg1_val = val;
902 return -1;
905 else if (!inc_insn.reg1_is_const
906 && rtx_equal_p (inc_insn.reg1, b))
907 /* Match with *(reg0 + reg1). */
908 return -1;
911 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
913 /* If REG occurs inside a MEM used in a bit-field reference,
914 that is unacceptable. */
915 if (find_address (&XEXP (x, 0)))
916 return 1;
919 if (x == inc_insn.reg_res)
920 return 1;
922 /* Time for some deep diving. */
923 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
925 if (fmt[i] == 'e')
927 tem = find_address (&XEXP (x, i));
928 /* If this is the first use, let it go so the rest of the
929 insn can be checked. */
930 if (value == 0)
931 value = tem;
932 else if (tem != 0)
933 /* More than one match was found. */
934 return 1;
936 else if (fmt[i] == 'E')
938 int j;
939 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
941 tem = find_address (&XVECEXP (x, i, j));
942 /* If this is the first use, let it go so the rest of
943 the insn can be checked. */
944 if (value == 0)
945 value = tem;
946 else if (tem != 0)
947 /* More than one match was found. */
948 return 1;
952 return value;
955 /* Once a suitable mem reference has been found and the MEM_INSN
956 structure has been filled in, FIND_INC is called to see if there is
957 a suitable add or inc insn that follows the mem reference and
958 determine if it is suitable to merge.
960 In the case where the MEM_INSN has two registers in the reference,
961 this function may be called recursively. The first time looking
962 for an add of the first register, and if that fails, looking for an
963 add of the second register. The FIRST_TRY parameter is used to
964 only allow the parameters to be reversed once. */
966 static bool
967 find_inc (bool first_try)
969 rtx insn;
970 basic_block bb = BLOCK_FOR_INSN (mem_insn.insn);
971 rtx other_insn;
972 df_ref *def_rec;
974 /* Make sure this reg appears only once in this insn. */
975 if (count_occurrences (PATTERN (mem_insn.insn), mem_insn.reg0, 1) != 1)
977 if (dump_file)
978 fprintf (dump_file, "mem count failure\n");
979 return false;
982 if (dump_file)
983 dump_mem_insn (dump_file);
985 /* Find the next use that is an inc. */
986 insn = get_next_ref (REGNO (mem_insn.reg0),
987 BLOCK_FOR_INSN (mem_insn.insn),
988 reg_next_inc_use);
989 if (!insn)
990 return false;
992 /* Even though we know the next use is an add or inc because it came
993 from the reg_next_inc_use, we must still reparse. */
994 if (!parse_add_or_inc (insn, false))
996 /* Next use was not an add. Look for one extra case. It could be
997 that we have:
999 *(a + b)
1000 ...= a;
1001 ...= b + a
1003 if we reverse the operands in the mem ref we would
1004 find this. Only try it once though. */
1005 if (first_try && !mem_insn.reg1_is_const)
1007 reverse_mem ();
1008 return find_inc (false);
1010 else
1011 return false;
1014 /* Need to assure that none of the operands of the inc instruction are
1015 assigned to by the mem insn. */
1016 for (def_rec = DF_INSN_DEFS (mem_insn.insn); *def_rec; def_rec++)
1018 df_ref def = *def_rec;
1019 unsigned int regno = DF_REF_REGNO (def);
1020 if ((regno == REGNO (inc_insn.reg0))
1021 || (regno == REGNO (inc_insn.reg_res)))
1023 if (dump_file)
1024 fprintf (dump_file, "inc conflicts with store failure.\n");
1025 return false;
1027 if (!inc_insn.reg1_is_const && (regno == REGNO (inc_insn.reg1)))
1029 if (dump_file)
1030 fprintf (dump_file, "inc conflicts with store failure.\n");
1031 return false;
1035 if (dump_file)
1036 dump_inc_insn (dump_file);
1038 if (inc_insn.form == FORM_POST_ADD)
1040 /* Make sure that there is no insn that assigns to inc_insn.res
1041 between the mem_insn and the inc_insn. */
1042 rtx other_insn = get_next_ref (REGNO (inc_insn.reg_res),
1043 BLOCK_FOR_INSN (mem_insn.insn),
1044 reg_next_def);
1045 if (other_insn != inc_insn.insn)
1047 if (dump_file)
1048 fprintf (dump_file,
1049 "result of add is assigned to between mem and inc insns.\n");
1050 return false;
1053 other_insn = get_next_ref (REGNO (inc_insn.reg_res),
1054 BLOCK_FOR_INSN (mem_insn.insn),
1055 reg_next_use);
1056 if (other_insn
1057 && (other_insn != inc_insn.insn)
1058 && (DF_INSN_LUID (inc_insn.insn) > DF_INSN_LUID (other_insn)))
1060 if (dump_file)
1061 fprintf (dump_file,
1062 "result of add is used between mem and inc insns.\n");
1063 return false;
1066 /* For the post_add to work, the result_reg of the inc must not be
1067 used in the mem insn since this will become the new index
1068 register. */
1069 if (reg_overlap_mentioned_p (inc_insn.reg_res, PATTERN (mem_insn.insn)))
1071 if (dump_file)
1072 fprintf (dump_file, "base reg replacement failure.\n");
1073 return false;
1077 if (mem_insn.reg1_is_const)
1079 if (mem_insn.reg1_val == 0)
1081 if (!inc_insn.reg1_is_const)
1083 /* The mem looks like *r0 and the rhs of the add has two
1084 registers. */
1085 int luid = DF_INSN_LUID (inc_insn.insn);
1086 if (inc_insn.form == FORM_POST_ADD)
1088 /* The trick is that we are not going to increment r0,
1089 we are going to increment the result of the add insn.
1090 For this trick to be correct, the result reg of
1091 the inc must be a valid addressing reg. */
1092 addr_space_t as = MEM_ADDR_SPACE (*mem_insn.mem_loc);
1093 if (GET_MODE (inc_insn.reg_res)
1094 != targetm.addr_space.address_mode (as))
1096 if (dump_file)
1097 fprintf (dump_file, "base reg mode failure.\n");
1098 return false;
1101 /* We also need to make sure that the next use of
1102 inc result is after the inc. */
1103 other_insn
1104 = get_next_ref (REGNO (inc_insn.reg1), bb, reg_next_use);
1105 if (other_insn && luid > DF_INSN_LUID (other_insn))
1106 return false;
1108 if (!rtx_equal_p (mem_insn.reg0, inc_insn.reg0))
1109 reverse_inc ();
1112 other_insn
1113 = get_next_ref (REGNO (inc_insn.reg1), bb, reg_next_def);
1114 if (other_insn && luid > DF_INSN_LUID (other_insn))
1115 return false;
1118 /* Both the inc/add and the mem have a constant. Need to check
1119 that the constants are ok. */
1120 else if ((mem_insn.reg1_val != inc_insn.reg1_val)
1121 && (mem_insn.reg1_val != -inc_insn.reg1_val))
1122 return false;
1124 else
1126 /* The mem insn is of the form *(a + b) where a and b are both
1127 regs. It may be that in order to match the add or inc we
1128 need to treat it as if it was *(b + a). It may also be that
1129 the add is of the form a + c where c does not match b and
1130 then we just abandon this. */
1132 int luid = DF_INSN_LUID (inc_insn.insn);
1133 rtx other_insn;
1135 /* Make sure this reg appears only once in this insn. */
1136 if (count_occurrences (PATTERN (mem_insn.insn), mem_insn.reg1, 1) != 1)
1137 return false;
1139 if (inc_insn.form == FORM_POST_ADD)
1141 /* For this trick to be correct, the result reg of the inc
1142 must be a valid addressing reg. */
1143 addr_space_t as = MEM_ADDR_SPACE (*mem_insn.mem_loc);
1144 if (GET_MODE (inc_insn.reg_res)
1145 != targetm.addr_space.address_mode (as))
1147 if (dump_file)
1148 fprintf (dump_file, "base reg mode failure.\n");
1149 return false;
1152 if (rtx_equal_p (mem_insn.reg0, inc_insn.reg0))
1154 if (!rtx_equal_p (mem_insn.reg1, inc_insn.reg1))
1156 /* See comment above on find_inc (false) call. */
1157 if (first_try)
1159 reverse_mem ();
1160 return find_inc (false);
1162 else
1163 return false;
1166 /* Need to check that there are no assignments to b
1167 before the add insn. */
1168 other_insn
1169 = get_next_ref (REGNO (inc_insn.reg1), bb, reg_next_def);
1170 if (other_insn && luid > DF_INSN_LUID (other_insn))
1171 return false;
1172 /* All ok for the next step. */
1174 else
1176 /* We know that mem_insn.reg0 must equal inc_insn.reg1
1177 or else we would not have found the inc insn. */
1178 reverse_mem ();
1179 if (!rtx_equal_p (mem_insn.reg0, inc_insn.reg0))
1181 /* See comment above on find_inc (false) call. */
1182 if (first_try)
1183 return find_inc (false);
1184 else
1185 return false;
1187 /* To have gotten here know that.
1188 *(b + a)
1190 ... = (b + a)
1192 We also know that the lhs of the inc is not b or a. We
1193 need to make sure that there are no assignments to b
1194 between the mem ref and the inc. */
1196 other_insn
1197 = get_next_ref (REGNO (inc_insn.reg0), bb, reg_next_def);
1198 if (other_insn && luid > DF_INSN_LUID (other_insn))
1199 return false;
1202 /* Need to check that the next use of the add result is later than
1203 add insn since this will be the reg incremented. */
1204 other_insn
1205 = get_next_ref (REGNO (inc_insn.reg_res), bb, reg_next_use);
1206 if (other_insn && luid > DF_INSN_LUID (other_insn))
1207 return false;
1209 else /* FORM_POST_INC. There is less to check here because we
1210 know that operands must line up. */
1212 if (!rtx_equal_p (mem_insn.reg1, inc_insn.reg1))
1213 /* See comment above on find_inc (false) call. */
1215 if (first_try)
1217 reverse_mem ();
1218 return find_inc (false);
1220 else
1221 return false;
1224 /* To have gotten here know that.
1225 *(a + b)
1227 ... = (a + b)
1229 We also know that the lhs of the inc is not b. We need to make
1230 sure that there are no assignments to b between the mem ref and
1231 the inc. */
1232 other_insn
1233 = get_next_ref (REGNO (inc_insn.reg1), bb, reg_next_def);
1234 if (other_insn && luid > DF_INSN_LUID (other_insn))
1235 return false;
1239 if (inc_insn.form == FORM_POST_INC)
1241 other_insn
1242 = get_next_ref (REGNO (inc_insn.reg0), bb, reg_next_use);
1243 /* When we found inc_insn, we were looking for the
1244 next add or inc, not the next insn that used the
1245 reg. Because we are going to increment the reg
1246 in this form, we need to make sure that there
1247 were no intervening uses of reg. */
1248 if (inc_insn.insn != other_insn)
1249 return false;
1252 return try_merge ();
1256 /* A recursive function that walks ADDRESS_OF_X to find all of the mem
1257 uses in pat that could be used as an auto inc or dec. It then
1258 calls FIND_INC for each one. */
1260 static bool
1261 find_mem (rtx *address_of_x)
1263 rtx x = *address_of_x;
1264 enum rtx_code code = GET_CODE (x);
1265 const char *const fmt = GET_RTX_FORMAT (code);
1266 int i;
1268 if (code == MEM && REG_P (XEXP (x, 0)))
1270 /* Match with *reg0. */
1271 mem_insn.mem_loc = address_of_x;
1272 mem_insn.reg0 = XEXP (x, 0);
1273 mem_insn.reg1_is_const = true;
1274 mem_insn.reg1_val = 0;
1275 mem_insn.reg1 = GEN_INT (0);
1276 if (find_inc (true))
1277 return true;
1279 if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
1280 && REG_P (XEXP (XEXP (x, 0), 0)))
1282 rtx reg1 = XEXP (XEXP (x, 0), 1);
1283 mem_insn.mem_loc = address_of_x;
1284 mem_insn.reg0 = XEXP (XEXP (x, 0), 0);
1285 mem_insn.reg1 = reg1;
1286 if (CONST_INT_P (reg1))
1288 mem_insn.reg1_is_const = true;
1289 /* Match with *(reg0 + c) where c is a const. */
1290 mem_insn.reg1_val = INTVAL (reg1);
1291 if (find_inc (true))
1292 return true;
1294 else if (REG_P (reg1))
1296 /* Match with *(reg0 + reg1). */
1297 mem_insn.reg1_is_const = false;
1298 if (find_inc (true))
1299 return true;
1303 if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
1305 /* If REG occurs inside a MEM used in a bit-field reference,
1306 that is unacceptable. */
1307 return false;
1310 /* Time for some deep diving. */
1311 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1313 if (fmt[i] == 'e')
1315 if (find_mem (&XEXP (x, i)))
1316 return true;
1318 else if (fmt[i] == 'E')
1320 int j;
1321 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
1322 if (find_mem (&XVECEXP (x, i, j)))
1323 return true;
1326 return false;
1330 /* Try to combine all incs and decs by constant values with memory
1331 references in BB. */
1333 static void
1334 merge_in_block (int max_reg, basic_block bb)
1336 rtx insn;
1337 rtx curr;
1338 int success_in_block = 0;
1340 if (dump_file)
1341 fprintf (dump_file, "\n\nstarting bb %d\n", bb->index);
1343 FOR_BB_INSNS_REVERSE_SAFE (bb, insn, curr)
1345 unsigned int uid = INSN_UID (insn);
1346 bool insn_is_add_or_inc = true;
1348 if (!NONDEBUG_INSN_P (insn))
1349 continue;
1351 /* This continue is deliberate. We do not want the uses of the
1352 jump put into reg_next_use because it is not considered safe to
1353 combine a preincrement with a jump. */
1354 if (JUMP_P (insn))
1355 continue;
1357 if (dump_file)
1358 dump_insn_slim (dump_file, insn);
1360 /* Does this instruction increment or decrement a register? */
1361 if (parse_add_or_inc (insn, true))
1363 int regno = REGNO (inc_insn.reg_res);
1364 /* Cannot handle case where there are three separate regs
1365 before a mem ref. Too many moves would be needed to be
1366 profitable. */
1367 if ((inc_insn.form == FORM_PRE_INC) || inc_insn.reg1_is_const)
1369 mem_insn.insn = get_next_ref (regno, bb, reg_next_use);
1370 if (mem_insn.insn)
1372 bool ok = true;
1373 if (!inc_insn.reg1_is_const)
1375 /* We are only here if we are going to try a
1376 HAVE_*_MODIFY_REG type transformation. c is a
1377 reg and we must sure that the path from the
1378 inc_insn to the mem_insn.insn is both def and use
1379 clear of c because the inc insn is going to move
1380 into the mem_insn.insn. */
1381 int luid = DF_INSN_LUID (mem_insn.insn);
1382 rtx other_insn
1383 = get_next_ref (REGNO (inc_insn.reg1), bb, reg_next_use);
1385 if (other_insn && luid > DF_INSN_LUID (other_insn))
1386 ok = false;
1388 other_insn
1389 = get_next_ref (REGNO (inc_insn.reg1), bb, reg_next_def);
1391 if (other_insn && luid > DF_INSN_LUID (other_insn))
1392 ok = false;
1395 if (dump_file)
1396 dump_inc_insn (dump_file);
1398 if (ok && find_address (&PATTERN (mem_insn.insn)) == -1)
1400 if (dump_file)
1401 dump_mem_insn (dump_file);
1402 if (try_merge ())
1404 success_in_block++;
1405 insn_is_add_or_inc = false;
1411 else
1413 insn_is_add_or_inc = false;
1414 mem_insn.insn = insn;
1415 if (find_mem (&PATTERN (insn)))
1416 success_in_block++;
1419 /* If the inc insn was merged with a mem, the inc insn is gone
1420 and there is noting to update. */
1421 if (DF_INSN_UID_GET (uid))
1423 df_ref *def_rec;
1424 df_ref *use_rec;
1425 /* Need to update next use. */
1426 for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)
1428 df_ref def = *def_rec;
1429 reg_next_use[DF_REF_REGNO (def)] = NULL;
1430 reg_next_inc_use[DF_REF_REGNO (def)] = NULL;
1431 reg_next_def[DF_REF_REGNO (def)] = insn;
1434 for (use_rec = DF_INSN_UID_USES (uid); *use_rec; use_rec++)
1436 df_ref use = *use_rec;
1437 reg_next_use[DF_REF_REGNO (use)] = insn;
1438 if (insn_is_add_or_inc)
1439 reg_next_inc_use[DF_REF_REGNO (use)] = insn;
1440 else
1441 reg_next_inc_use[DF_REF_REGNO (use)] = NULL;
1444 else if (dump_file)
1445 fprintf (dump_file, "skipping update of deleted insn %d\n", uid);
1448 /* If we were successful, try again. There may have been several
1449 opportunities that were interleaved. This is rare but
1450 gcc.c-torture/compile/pr17273.c actually exhibits this. */
1451 if (success_in_block)
1453 /* In this case, we must clear these vectors since the trick of
1454 testing if the stale insn in the block will not work. */
1455 memset (reg_next_use, 0, max_reg * sizeof(rtx));
1456 memset (reg_next_inc_use, 0, max_reg * sizeof(rtx));
1457 memset (reg_next_def, 0, max_reg * sizeof(rtx));
1458 df_recompute_luids (bb);
1459 merge_in_block (max_reg, bb);
1463 #endif
1465 static unsigned int
1466 rest_of_handle_auto_inc_dec (void)
1468 #ifdef AUTO_INC_DEC
1469 basic_block bb;
1470 int max_reg = max_reg_num ();
1472 if (!initialized)
1473 init_decision_table ();
1475 mem_tmp = gen_rtx_MEM (Pmode, NULL_RTX);
1477 df_note_add_problem ();
1478 df_analyze ();
1480 reg_next_use = XCNEWVEC (rtx, max_reg);
1481 reg_next_inc_use = XCNEWVEC (rtx, max_reg);
1482 reg_next_def = XCNEWVEC (rtx, max_reg);
1483 FOR_EACH_BB (bb)
1484 merge_in_block (max_reg, bb);
1486 free (reg_next_use);
1487 free (reg_next_inc_use);
1488 free (reg_next_def);
1490 mem_tmp = NULL;
1491 #endif
1492 return 0;
1496 /* Discover auto-inc auto-dec instructions. */
1498 static bool
1499 gate_auto_inc_dec (void)
1501 #ifdef AUTO_INC_DEC
1502 return (optimize > 0 && flag_auto_inc_dec);
1503 #else
1504 return false;
1505 #endif
1509 struct rtl_opt_pass pass_inc_dec =
1512 RTL_PASS,
1513 "auto_inc_dec", /* name */
1514 OPTGROUP_NONE, /* optinfo_flags */
1515 gate_auto_inc_dec, /* gate */
1516 rest_of_handle_auto_inc_dec, /* execute */
1517 NULL, /* sub */
1518 NULL, /* next */
1519 0, /* static_pass_number */
1520 TV_AUTO_INC_DEC, /* tv_id */
1521 0, /* properties_required */
1522 0, /* properties_provided */
1523 0, /* properties_destroyed */
1524 0, /* todo_flags_start */
1525 TODO_df_finish, /* todo_flags_finish */