1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it
7 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 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 #include "coretypes.h"
30 #include "insn-config.h"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
45 #ifndef HAVE_conditional_execution
46 #define HAVE_conditional_execution 0
48 #ifndef HAVE_conditional_move
49 #define HAVE_conditional_move 0
60 #ifndef HAVE_conditional_trap
61 #define HAVE_conditional_trap 0
64 #ifndef MAX_CONDITIONAL_EXECUTE
65 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
68 #define NULL_EDGE ((struct edge_def *)NULL)
69 #define NULL_BLOCK ((struct basic_block_def *)NULL)
71 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
72 static int num_possible_if_blocks;
74 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
76 static int num_updated_if_blocks;
78 /* # of changes made which require life information to be updated. */
79 static int num_true_changes;
81 /* Whether conditional execution changes were made. */
82 static int cond_exec_changed_p;
84 /* True if life data ok at present. */
85 static bool life_data_ok;
87 /* The post-dominator relation on the original block numbers. */
88 static dominance_info post_dominators;
90 /* Forward references. */
91 static int count_bb_insns (basic_block);
92 static rtx first_active_insn (basic_block);
93 static rtx last_active_insn (basic_block, int);
94 static int seq_contains_jump (rtx);
95 static basic_block block_fallthru (basic_block);
96 static int cond_exec_process_insns (ce_if_block_t *, rtx, rtx, rtx, rtx, int);
97 static rtx cond_exec_get_condition (rtx);
98 static int cond_exec_process_if_block (ce_if_block_t *, int);
99 static rtx noce_get_condition (rtx, rtx *);
100 static int noce_operand_ok (rtx);
101 static int noce_process_if_block (ce_if_block_t *);
102 static int process_if_block (ce_if_block_t *);
103 static void merge_if_block (ce_if_block_t *);
104 static int find_cond_trap (basic_block, edge, edge);
105 static basic_block find_if_header (basic_block, int);
106 static int block_jumps_and_fallthru_p (basic_block, basic_block);
107 static int find_if_block (ce_if_block_t *);
108 static int find_if_case_1 (basic_block, edge, edge);
109 static int find_if_case_2 (basic_block, edge, edge);
110 static int find_memory (rtx *, void *);
111 static int dead_or_predicable (basic_block, basic_block, basic_block,
113 static void noce_emit_move_insn (rtx, rtx);
114 static rtx block_has_only_trap (basic_block);
115 static void mark_loop_exit_edges (void);
117 /* Sets EDGE_LOOP_EXIT flag for all loop exits. */
119 mark_loop_exit_edges (void)
125 flow_loops_find (&loops, LOOP_TREE);
131 for (e = bb->succ; e; e = e->succ_next)
133 if (find_common_loop (bb->loop_father, e->dest->loop_father)
135 e->flags |= EDGE_LOOP_EXIT;
137 e->flags &= ~EDGE_LOOP_EXIT;
142 flow_loops_free (&loops);
145 /* Count the number of non-jump active insns in BB. */
148 count_bb_insns (basic_block bb)
155 if (GET_CODE (insn) == CALL_INSN || GET_CODE (insn) == INSN)
160 insn = NEXT_INSN (insn);
166 /* Return the first non-jump active insn in the basic block. */
169 first_active_insn (basic_block bb)
173 if (GET_CODE (insn) == CODE_LABEL)
177 insn = NEXT_INSN (insn);
180 while (GET_CODE (insn) == NOTE)
184 insn = NEXT_INSN (insn);
187 if (GET_CODE (insn) == JUMP_INSN)
193 /* Return the last non-jump active (non-jump) insn in the basic block. */
196 last_active_insn (basic_block bb, int skip_use_p)
201 while (GET_CODE (insn) == NOTE
202 || GET_CODE (insn) == JUMP_INSN
204 && GET_CODE (insn) == INSN
205 && GET_CODE (PATTERN (insn)) == USE))
209 insn = PREV_INSN (insn);
212 if (GET_CODE (insn) == CODE_LABEL)
218 /* It is possible, especially when having dealt with multi-word
219 arithmetic, for the expanders to have emitted jumps. Search
220 through the sequence and return TRUE if a jump exists so that
221 we can abort the conversion. */
224 seq_contains_jump (rtx insn)
228 if (GET_CODE (insn) == JUMP_INSN)
230 insn = NEXT_INSN (insn);
236 block_fallthru (basic_block bb)
241 e != NULL_EDGE && (e->flags & EDGE_FALLTHRU) == 0;
245 return (e) ? e->dest : NULL_BLOCK;
248 /* Go through a bunch of insns, converting them to conditional
249 execution format if possible. Return TRUE if all of the non-note
250 insns were processed. */
253 cond_exec_process_insns (ce_if_block_t *ce_info ATTRIBUTE_UNUSED,
254 /* if block information */rtx start,
255 /* first insn to look at */rtx end,
256 /* last insn to look at */rtx test,
257 /* conditional execution test */rtx prob_val,
258 /* probability of branch taken. */int mod_ok)
260 int must_be_last = FALSE;
268 for (insn = start; ; insn = NEXT_INSN (insn))
270 if (GET_CODE (insn) == NOTE)
273 if (GET_CODE (insn) != INSN && GET_CODE (insn) != CALL_INSN)
276 /* Remove USE insns that get in the way. */
277 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
279 /* ??? Ug. Actually unlinking the thing is problematic,
280 given what we'd have to coordinate with our callers. */
281 PUT_CODE (insn, NOTE);
282 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
283 NOTE_SOURCE_FILE (insn) = 0;
287 /* Last insn wasn't last? */
291 if (modified_in_p (test, insn))
298 /* Now build the conditional form of the instruction. */
299 pattern = PATTERN (insn);
300 xtest = copy_rtx (test);
302 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
304 if (GET_CODE (pattern) == COND_EXEC)
306 if (GET_MODE (xtest) != GET_MODE (COND_EXEC_TEST (pattern)))
309 xtest = gen_rtx_AND (GET_MODE (xtest), xtest,
310 COND_EXEC_TEST (pattern));
311 pattern = COND_EXEC_CODE (pattern);
314 pattern = gen_rtx_COND_EXEC (VOIDmode, xtest, pattern);
316 /* If the machine needs to modify the insn being conditionally executed,
317 say for example to force a constant integer operand into a temp
318 register, do so here. */
319 #ifdef IFCVT_MODIFY_INSN
320 IFCVT_MODIFY_INSN (ce_info, pattern, insn);
325 validate_change (insn, &PATTERN (insn), pattern, 1);
327 if (GET_CODE (insn) == CALL_INSN && prob_val)
328 validate_change (insn, ®_NOTES (insn),
329 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
330 REG_NOTES (insn)), 1);
340 /* Return the condition for a jump. Do not do any special processing. */
343 cond_exec_get_condition (rtx jump)
347 if (any_condjump_p (jump))
348 test_if = SET_SRC (pc_set (jump));
351 cond = XEXP (test_if, 0);
353 /* If this branches to JUMP_LABEL when the condition is false,
354 reverse the condition. */
355 if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF
356 && XEXP (XEXP (test_if, 2), 0) == JUMP_LABEL (jump))
358 enum rtx_code rev = reversed_comparison_code (cond, jump);
362 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
369 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
370 to conditional execution. Return TRUE if we were successful at
371 converting the block. */
374 cond_exec_process_if_block (ce_if_block_t * ce_info,
375 /* if block information */int do_multiple_p)
377 basic_block test_bb = ce_info->test_bb; /* last test block */
378 basic_block then_bb = ce_info->then_bb; /* THEN */
379 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
380 rtx test_expr; /* expression in IF_THEN_ELSE that is tested */
381 rtx then_start; /* first insn in THEN block */
382 rtx then_end; /* last insn + 1 in THEN block */
383 rtx else_start = NULL_RTX; /* first insn in ELSE block or NULL */
384 rtx else_end = NULL_RTX; /* last insn + 1 in ELSE block */
385 int max; /* max # of insns to convert. */
386 int then_mod_ok; /* whether conditional mods are ok in THEN */
387 rtx true_expr; /* test for else block insns */
388 rtx false_expr; /* test for then block insns */
389 rtx true_prob_val; /* probability of else block */
390 rtx false_prob_val; /* probability of then block */
392 enum rtx_code false_code;
394 /* If test is comprised of && or || elements, and we've failed at handling
395 all of them together, just use the last test if it is the special case of
396 && elements without an ELSE block. */
397 if (!do_multiple_p && ce_info->num_multiple_test_blocks)
399 if (else_bb || ! ce_info->and_and_p)
402 ce_info->test_bb = test_bb = ce_info->last_test_bb;
403 ce_info->num_multiple_test_blocks = 0;
404 ce_info->num_and_and_blocks = 0;
405 ce_info->num_or_or_blocks = 0;
408 /* Find the conditional jump to the ELSE or JOIN part, and isolate
410 test_expr = cond_exec_get_condition (test_bb->end);
414 /* If the conditional jump is more than just a conditional jump,
415 then we can not do conditional execution conversion on this block. */
416 if (! onlyjump_p (test_bb->end))
419 /* Collect the bounds of where we're to search, skipping any labels, jumps
420 and notes at the beginning and end of the block. Then count the total
421 number of insns and see if it is small enough to convert. */
422 then_start = first_active_insn (then_bb);
423 then_end = last_active_insn (then_bb, TRUE);
424 n_insns = ce_info->num_then_insns = count_bb_insns (then_bb);
425 max = MAX_CONDITIONAL_EXECUTE;
430 else_start = first_active_insn (else_bb);
431 else_end = last_active_insn (else_bb, TRUE);
432 n_insns += ce_info->num_else_insns = count_bb_insns (else_bb);
438 /* Map test_expr/test_jump into the appropriate MD tests to use on
439 the conditionally executed code. */
441 true_expr = test_expr;
443 false_code = reversed_comparison_code (true_expr, test_bb->end);
444 if (false_code != UNKNOWN)
445 false_expr = gen_rtx_fmt_ee (false_code, GET_MODE (true_expr),
446 XEXP (true_expr, 0), XEXP (true_expr, 1));
448 false_expr = NULL_RTX;
450 #ifdef IFCVT_MODIFY_TESTS
451 /* If the machine description needs to modify the tests, such as setting a
452 conditional execution register from a comparison, it can do so here. */
453 IFCVT_MODIFY_TESTS (ce_info, true_expr, false_expr);
455 /* See if the conversion failed */
456 if (!true_expr || !false_expr)
460 true_prob_val = find_reg_note (test_bb->end, REG_BR_PROB, NULL_RTX);
463 true_prob_val = XEXP (true_prob_val, 0);
464 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
467 false_prob_val = NULL_RTX;
469 /* If we have && or || tests, do them here. These tests are in the adjacent
470 blocks after the first block containing the test. */
471 if (ce_info->num_multiple_test_blocks > 0)
473 basic_block bb = test_bb;
474 basic_block last_test_bb = ce_info->last_test_bb;
484 bb = block_fallthru (bb);
485 start = first_active_insn (bb);
486 end = last_active_insn (bb, TRUE);
488 && ! cond_exec_process_insns (ce_info, start, end, false_expr,
489 false_prob_val, FALSE))
492 /* If the conditional jump is more than just a conditional jump, then
493 we can not do conditional execution conversion on this block. */
494 if (! onlyjump_p (bb->end))
497 /* Find the conditional jump and isolate the test. */
498 t = cond_exec_get_condition (bb->end);
502 f = gen_rtx_fmt_ee (reverse_condition (GET_CODE (t)),
507 if (ce_info->and_and_p)
509 t = gen_rtx_AND (GET_MODE (t), true_expr, t);
510 f = gen_rtx_IOR (GET_MODE (t), false_expr, f);
514 t = gen_rtx_IOR (GET_MODE (t), true_expr, t);
515 f = gen_rtx_AND (GET_MODE (t), false_expr, f);
518 /* If the machine description needs to modify the tests, such as
519 setting a conditional execution register from a comparison, it can
521 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
522 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info, bb, t, f);
524 /* See if the conversion failed */
532 while (bb != last_test_bb);
535 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
536 on then THEN block. */
537 then_mod_ok = (else_bb == NULL_BLOCK);
539 /* Go through the THEN and ELSE blocks converting the insns if possible
540 to conditional execution. */
544 || ! cond_exec_process_insns (ce_info, then_start, then_end,
545 false_expr, false_prob_val,
549 if (else_bb && else_end
550 && ! cond_exec_process_insns (ce_info, else_start, else_end,
551 true_expr, true_prob_val, TRUE))
554 /* If we cannot apply the changes, fail. Do not go through the normal fail
555 processing, since apply_change_group will call cancel_changes. */
556 if (! apply_change_group ())
558 #ifdef IFCVT_MODIFY_CANCEL
559 /* Cancel any machine dependent changes. */
560 IFCVT_MODIFY_CANCEL (ce_info);
565 #ifdef IFCVT_MODIFY_FINAL
566 /* Do any machine dependent final modifications */
567 IFCVT_MODIFY_FINAL (ce_info);
570 /* Conversion succeeded. */
572 fprintf (rtl_dump_file, "%d insn%s converted to conditional execution.\n",
573 n_insns, (n_insns == 1) ? " was" : "s were");
575 /* Merge the blocks! */
576 merge_if_block (ce_info);
577 cond_exec_changed_p = TRUE;
581 #ifdef IFCVT_MODIFY_CANCEL
582 /* Cancel any machine dependent changes. */
583 IFCVT_MODIFY_CANCEL (ce_info);
590 /* Used by noce_process_if_block to communicate with its subroutines.
592 The subroutines know that A and B may be evaluated freely. They
593 know that X is a register. They should insert new instructions
594 before cond_earliest. */
601 rtx jump, cond, cond_earliest;
604 static rtx noce_emit_store_flag (struct noce_if_info *, rtx, int, int);
605 static int noce_try_move (struct noce_if_info *);
606 static int noce_try_store_flag (struct noce_if_info *);
607 static int noce_try_addcc (struct noce_if_info *);
608 static int noce_try_store_flag_constants (struct noce_if_info *);
609 static int noce_try_store_flag_mask (struct noce_if_info *);
610 static rtx noce_emit_cmove (struct noce_if_info *, rtx, enum rtx_code, rtx,
612 static int noce_try_cmove (struct noce_if_info *);
613 static int noce_try_cmove_arith (struct noce_if_info *);
614 static rtx noce_get_alt_condition (struct noce_if_info *, rtx, rtx *);
615 static int noce_try_minmax (struct noce_if_info *);
616 static int noce_try_abs (struct noce_if_info *);
618 /* Helper function for noce_try_store_flag*. */
621 noce_emit_store_flag (struct noce_if_info *if_info, rtx x, int reversep,
624 rtx cond = if_info->cond;
628 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
629 || ! general_operand (XEXP (cond, 1), VOIDmode));
631 /* If earliest == jump, or when the condition is complex, try to
632 build the store_flag insn directly. */
635 cond = XEXP (SET_SRC (pc_set (if_info->jump)), 0);
638 code = reversed_comparison_code (cond, if_info->jump);
640 code = GET_CODE (cond);
642 if ((if_info->cond_earliest == if_info->jump || cond_complex)
643 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
647 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
649 tmp = gen_rtx_SET (VOIDmode, x, tmp);
652 tmp = emit_insn (tmp);
654 if (recog_memoized (tmp) >= 0)
660 if_info->cond_earliest = if_info->jump;
668 /* Don't even try if the comparison operands or the mode of X are weird. */
669 if (cond_complex || !SCALAR_INT_MODE_P (GET_MODE (x)))
672 return emit_store_flag (x, code, XEXP (cond, 0),
673 XEXP (cond, 1), VOIDmode,
674 (code == LTU || code == LEU
675 || code == GEU || code == GTU), normalize);
678 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
679 X is the destination/target and Y is the value to copy. */
682 noce_emit_move_insn (rtx x, rtx y)
684 enum machine_mode outmode, inmode;
688 if (GET_CODE (x) != STRICT_LOW_PART)
690 emit_move_insn (x, y);
695 inner = XEXP (outer, 0);
696 outmode = GET_MODE (outer);
697 inmode = GET_MODE (inner);
698 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
699 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y,
700 GET_MODE_BITSIZE (inmode));
703 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
704 "if (a == b) x = a; else x = b" into "x = b". */
707 noce_try_move (struct noce_if_info *if_info)
709 rtx cond = if_info->cond;
710 enum rtx_code code = GET_CODE (cond);
713 if (code != NE && code != EQ)
716 /* This optimization isn't valid if either A or B could be a NaN
718 if (HONOR_NANS (GET_MODE (if_info->x))
719 || HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
722 /* Check whether the operands of the comparison are A and in
724 if ((rtx_equal_p (if_info->a, XEXP (cond, 0))
725 && rtx_equal_p (if_info->b, XEXP (cond, 1)))
726 || (rtx_equal_p (if_info->a, XEXP (cond, 1))
727 && rtx_equal_p (if_info->b, XEXP (cond, 0))))
729 y = (code == EQ) ? if_info->a : if_info->b;
731 /* Avoid generating the move if the source is the destination. */
732 if (! rtx_equal_p (if_info->x, y))
735 noce_emit_move_insn (if_info->x, y);
738 emit_insn_before_setloc (seq, if_info->jump,
739 INSN_LOCATOR (if_info->insn_a));
746 /* Convert "if (test) x = 1; else x = 0".
748 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
749 tried in noce_try_store_flag_constants after noce_try_cmove has had
750 a go at the conversion. */
753 noce_try_store_flag (struct noce_if_info *if_info)
758 if (GET_CODE (if_info->b) == CONST_INT
759 && INTVAL (if_info->b) == STORE_FLAG_VALUE
760 && if_info->a == const0_rtx)
762 else if (if_info->b == const0_rtx
763 && GET_CODE (if_info->a) == CONST_INT
764 && INTVAL (if_info->a) == STORE_FLAG_VALUE
765 && (reversed_comparison_code (if_info->cond, if_info->jump)
773 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
776 if (target != if_info->x)
777 noce_emit_move_insn (if_info->x, target);
781 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
792 /* Convert "if (test) x = a; else x = b", for A and B constant. */
795 noce_try_store_flag_constants (struct noce_if_info *if_info)
799 HOST_WIDE_INT itrue, ifalse, diff, tmp;
800 int normalize, can_reverse;
801 enum machine_mode mode;
804 && GET_CODE (if_info->a) == CONST_INT
805 && GET_CODE (if_info->b) == CONST_INT)
807 mode = GET_MODE (if_info->x);
808 ifalse = INTVAL (if_info->a);
809 itrue = INTVAL (if_info->b);
811 /* Make sure we can represent the difference between the two values. */
812 if ((itrue - ifalse > 0)
813 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
816 diff = trunc_int_for_mode (itrue - ifalse, mode);
818 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
822 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
824 else if (ifalse == 0 && exact_log2 (itrue) >= 0
825 && (STORE_FLAG_VALUE == 1
826 || BRANCH_COST >= 2))
828 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
829 && (STORE_FLAG_VALUE == 1 || BRANCH_COST >= 2))
830 normalize = 1, reversep = 1;
832 && (STORE_FLAG_VALUE == -1
833 || BRANCH_COST >= 2))
835 else if (ifalse == -1 && can_reverse
836 && (STORE_FLAG_VALUE == -1 || BRANCH_COST >= 2))
837 normalize = -1, reversep = 1;
838 else if ((BRANCH_COST >= 2 && STORE_FLAG_VALUE == -1)
846 tmp = itrue; itrue = ifalse; ifalse = tmp;
847 diff = trunc_int_for_mode (-diff, mode);
851 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
858 /* if (test) x = 3; else x = 4;
859 => x = 3 + (test == 0); */
860 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
862 target = expand_simple_binop (mode,
863 (diff == STORE_FLAG_VALUE
865 GEN_INT (ifalse), target, if_info->x, 0,
869 /* if (test) x = 8; else x = 0;
870 => x = (test != 0) << 3; */
871 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
873 target = expand_simple_binop (mode, ASHIFT,
874 target, GEN_INT (tmp), if_info->x, 0,
878 /* if (test) x = -1; else x = b;
879 => x = -(test != 0) | b; */
880 else if (itrue == -1)
882 target = expand_simple_binop (mode, IOR,
883 target, GEN_INT (ifalse), if_info->x, 0,
887 /* if (test) x = a; else x = b;
888 => x = (-(test != 0) & (b - a)) + a; */
891 target = expand_simple_binop (mode, AND,
892 target, GEN_INT (diff), if_info->x, 0,
895 target = expand_simple_binop (mode, PLUS,
896 target, GEN_INT (ifalse),
897 if_info->x, 0, OPTAB_WIDEN);
906 if (target != if_info->x)
907 noce_emit_move_insn (if_info->x, target);
912 if (seq_contains_jump (seq))
915 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
923 /* Convert "if (test) foo++" into "foo += (test != 0)", and
924 similarly for "foo--". */
927 noce_try_addcc (struct noce_if_info *if_info)
930 int subtract, normalize;
933 && GET_CODE (if_info->a) == PLUS
934 && rtx_equal_p (XEXP (if_info->a, 0), if_info->b)
935 && (reversed_comparison_code (if_info->cond, if_info->jump)
938 rtx cond = if_info->cond;
939 enum rtx_code code = reversed_comparison_code (cond, if_info->jump);
941 /* First try to use addcc pattern. */
942 if (general_operand (XEXP (cond, 0), VOIDmode)
943 && general_operand (XEXP (cond, 1), VOIDmode))
946 target = emit_conditional_add (if_info->x, code,
947 XEXP (cond, 0), XEXP (cond, 1),
949 if_info->b, XEXP (if_info->a, 1),
950 GET_MODE (if_info->x),
951 (code == LTU || code == GEU
952 || code == LEU || code == GTU));
955 if (target != if_info->x)
956 noce_emit_move_insn (if_info->x, target);
960 emit_insn_before_setloc (seq, if_info->jump,
961 INSN_LOCATOR (if_info->insn_a));
967 /* If that fails, construct conditional increment or decrement using
970 && (XEXP (if_info->a, 1) == const1_rtx
971 || XEXP (if_info->a, 1) == constm1_rtx))
974 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
975 subtract = 0, normalize = 0;
976 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
977 subtract = 1, normalize = 0;
979 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
982 target = noce_emit_store_flag (if_info,
983 gen_reg_rtx (GET_MODE (if_info->x)),
987 target = expand_simple_binop (GET_MODE (if_info->x),
988 subtract ? MINUS : PLUS,
989 if_info->b, target, if_info->x,
993 if (target != if_info->x)
994 noce_emit_move_insn (if_info->x, target);
999 if (seq_contains_jump (seq))
1002 emit_insn_before_setloc (seq, if_info->jump,
1003 INSN_LOCATOR (if_info->insn_a));
1014 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1017 noce_try_store_flag_mask (struct noce_if_info *if_info)
1023 if (! no_new_pseudos
1024 && (BRANCH_COST >= 2
1025 || STORE_FLAG_VALUE == -1)
1026 && ((if_info->a == const0_rtx
1027 && rtx_equal_p (if_info->b, if_info->x))
1028 || ((reversep = (reversed_comparison_code (if_info->cond,
1031 && if_info->b == const0_rtx
1032 && rtx_equal_p (if_info->a, if_info->x))))
1035 target = noce_emit_store_flag (if_info,
1036 gen_reg_rtx (GET_MODE (if_info->x)),
1039 target = expand_simple_binop (GET_MODE (if_info->x), AND,
1040 if_info->x, target, if_info->x, 0,
1045 if (target != if_info->x)
1046 noce_emit_move_insn (if_info->x, target);
1051 if (seq_contains_jump (seq))
1054 emit_insn_before_setloc (seq, if_info->jump,
1055 INSN_LOCATOR (if_info->insn_a));
1066 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1069 noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code,
1070 rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue)
1072 /* If earliest == jump, try to build the cmove insn directly.
1073 This is helpful when combine has created some complex condition
1074 (like for alpha's cmovlbs) that we can't hope to regenerate
1075 through the normal interface. */
1077 if (if_info->cond_earliest == if_info->jump)
1081 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
1082 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
1083 tmp = gen_rtx_SET (VOIDmode, x, tmp);
1086 tmp = emit_insn (tmp);
1088 if (recog_memoized (tmp) >= 0)
1100 /* Don't even try if the comparison operands are weird. */
1101 if (! general_operand (cmp_a, GET_MODE (cmp_a))
1102 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
1105 #if HAVE_conditional_move
1106 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
1107 vtrue, vfalse, GET_MODE (x),
1108 (code == LTU || code == GEU
1109 || code == LEU || code == GTU));
1111 /* We'll never get here, as noce_process_if_block doesn't call the
1112 functions involved. Ifdef code, however, should be discouraged
1113 because it leads to typos in the code not selected. However,
1114 emit_conditional_move won't exist either. */
1119 /* Try only simple constants and registers here. More complex cases
1120 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1121 has had a go at it. */
1124 noce_try_cmove (struct noce_if_info *if_info)
1129 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
1130 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
1134 code = GET_CODE (if_info->cond);
1135 target = noce_emit_cmove (if_info, if_info->x, code,
1136 XEXP (if_info->cond, 0),
1137 XEXP (if_info->cond, 1),
1138 if_info->a, if_info->b);
1142 if (target != if_info->x)
1143 noce_emit_move_insn (if_info->x, target);
1147 emit_insn_before_setloc (seq, if_info->jump,
1148 INSN_LOCATOR (if_info->insn_a));
1161 /* Try more complex cases involving conditional_move. */
1164 noce_try_cmove_arith (struct noce_if_info *if_info)
1174 /* A conditional move from two memory sources is equivalent to a
1175 conditional on their addresses followed by a load. Don't do this
1176 early because it'll screw alias analysis. Note that we've
1177 already checked for no side effects. */
1178 if (! no_new_pseudos && cse_not_expected
1179 && GET_CODE (a) == MEM && GET_CODE (b) == MEM
1180 && BRANCH_COST >= 5)
1184 x = gen_reg_rtx (Pmode);
1188 /* ??? We could handle this if we knew that a load from A or B could
1189 not fault. This is also true if we've already loaded
1190 from the address along the path from ENTRY. */
1191 else if (may_trap_p (a) || may_trap_p (b))
1194 /* if (test) x = a + b; else x = c - d;
1201 code = GET_CODE (if_info->cond);
1202 insn_a = if_info->insn_a;
1203 insn_b = if_info->insn_b;
1205 /* Possibly rearrange operands to make things come out more natural. */
1206 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1209 if (rtx_equal_p (b, x))
1211 else if (general_operand (b, GET_MODE (b)))
1216 code = reversed_comparison_code (if_info->cond, if_info->jump);
1217 tmp = a, a = b, b = tmp;
1218 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1224 /* If either operand is complex, load it into a register first.
1225 The best way to do this is to copy the original insn. In this
1226 way we preserve any clobbers etc that the insn may have had.
1227 This is of course not possible in the IS_MEM case. */
1228 if (! general_operand (a, GET_MODE (a)))
1233 goto end_seq_and_fail;
1237 tmp = gen_reg_rtx (GET_MODE (a));
1238 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1241 goto end_seq_and_fail;
1244 a = gen_reg_rtx (GET_MODE (a));
1245 tmp = copy_rtx (insn_a);
1246 set = single_set (tmp);
1248 tmp = emit_insn (PATTERN (tmp));
1250 if (recog_memoized (tmp) < 0)
1251 goto end_seq_and_fail;
1253 if (! general_operand (b, GET_MODE (b)))
1258 goto end_seq_and_fail;
1262 tmp = gen_reg_rtx (GET_MODE (b));
1263 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, b));
1266 goto end_seq_and_fail;
1269 b = gen_reg_rtx (GET_MODE (b));
1270 tmp = copy_rtx (insn_b);
1271 set = single_set (tmp);
1273 tmp = emit_insn (PATTERN (tmp));
1275 if (recog_memoized (tmp) < 0)
1276 goto end_seq_and_fail;
1279 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1280 XEXP (if_info->cond, 1), a, b);
1283 goto end_seq_and_fail;
1285 /* If we're handling a memory for above, emit the load now. */
1288 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1290 /* Copy over flags as appropriate. */
1291 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1292 MEM_VOLATILE_P (tmp) = 1;
1293 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1294 MEM_IN_STRUCT_P (tmp) = 1;
1295 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1296 MEM_SCALAR_P (tmp) = 1;
1297 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1298 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1300 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1302 noce_emit_move_insn (if_info->x, tmp);
1304 else if (target != x)
1305 noce_emit_move_insn (x, target);
1309 emit_insn_before_setloc (tmp, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1317 /* For most cases, the simplified condition we found is the best
1318 choice, but this is not the case for the min/max/abs transforms.
1319 For these we wish to know that it is A or B in the condition. */
1322 noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
1325 rtx cond, set, insn;
1328 /* If target is already mentioned in the known condition, return it. */
1329 if (reg_mentioned_p (target, if_info->cond))
1331 *earliest = if_info->cond_earliest;
1332 return if_info->cond;
1335 set = pc_set (if_info->jump);
1336 cond = XEXP (SET_SRC (set), 0);
1338 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1339 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1341 /* If we're looking for a constant, try to make the conditional
1342 have that constant in it. There are two reasons why it may
1343 not have the constant we want:
1345 1. GCC may have needed to put the constant in a register, because
1346 the target can't compare directly against that constant. For
1347 this case, we look for a SET immediately before the comparison
1348 that puts a constant in that register.
1350 2. GCC may have canonicalized the conditional, for example
1351 replacing "if x < 4" with "if x <= 3". We can undo that (or
1352 make equivalent types of changes) to get the constants we need
1353 if they're off by one in the right direction. */
1355 if (GET_CODE (target) == CONST_INT)
1357 enum rtx_code code = GET_CODE (if_info->cond);
1358 rtx op_a = XEXP (if_info->cond, 0);
1359 rtx op_b = XEXP (if_info->cond, 1);
1362 /* First, look to see if we put a constant in a register. */
1363 prev_insn = PREV_INSN (if_info->cond_earliest);
1365 && INSN_P (prev_insn)
1366 && GET_CODE (PATTERN (prev_insn)) == SET)
1368 rtx src = find_reg_equal_equiv_note (prev_insn);
1370 src = SET_SRC (PATTERN (prev_insn));
1371 if (GET_CODE (src) == CONST_INT)
1373 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1375 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1378 if (GET_CODE (op_a) == CONST_INT)
1383 code = swap_condition (code);
1388 /* Now, look to see if we can get the right constant by
1389 adjusting the conditional. */
1390 if (GET_CODE (op_b) == CONST_INT)
1392 HOST_WIDE_INT desired_val = INTVAL (target);
1393 HOST_WIDE_INT actual_val = INTVAL (op_b);
1398 if (actual_val == desired_val + 1)
1401 op_b = GEN_INT (desired_val);
1405 if (actual_val == desired_val - 1)
1408 op_b = GEN_INT (desired_val);
1412 if (actual_val == desired_val - 1)
1415 op_b = GEN_INT (desired_val);
1419 if (actual_val == desired_val + 1)
1422 op_b = GEN_INT (desired_val);
1430 /* If we made any changes, generate a new conditional that is
1431 equivalent to what we started with, but has the right
1433 if (code != GET_CODE (if_info->cond)
1434 || op_a != XEXP (if_info->cond, 0)
1435 || op_b != XEXP (if_info->cond, 1))
1437 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1438 *earliest = if_info->cond_earliest;
1443 cond = canonicalize_condition (if_info->jump, cond, reverse,
1444 earliest, target, false);
1445 if (! cond || ! reg_mentioned_p (target, cond))
1448 /* We almost certainly searched back to a different place.
1449 Need to re-verify correct lifetimes. */
1451 /* X may not be mentioned in the range (cond_earliest, jump]. */
1452 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1453 if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
1456 /* A and B may not be modified in the range [cond_earliest, jump). */
1457 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1459 && (modified_in_p (if_info->a, insn)
1460 || modified_in_p (if_info->b, insn)))
1466 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1469 noce_try_minmax (struct noce_if_info *if_info)
1471 rtx cond, earliest, target, seq;
1472 enum rtx_code code, op;
1475 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1479 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1480 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1481 to get the target to tell us... */
1482 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1483 || HONOR_NANS (GET_MODE (if_info->x)))
1486 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1490 /* Verify the condition is of the form we expect, and canonicalize
1491 the comparison code. */
1492 code = GET_CODE (cond);
1493 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1495 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1498 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1500 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1502 code = swap_condition (code);
1507 /* Determine what sort of operation this is. Note that the code is for
1508 a taken branch, so the code->operation mapping appears backwards. */
1541 target = expand_simple_binop (GET_MODE (if_info->x), op,
1542 if_info->a, if_info->b,
1543 if_info->x, unsignedp, OPTAB_WIDEN);
1549 if (target != if_info->x)
1550 noce_emit_move_insn (if_info->x, target);
1555 if (seq_contains_jump (seq))
1558 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1559 if_info->cond = cond;
1560 if_info->cond_earliest = earliest;
1565 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1568 noce_try_abs (struct noce_if_info *if_info)
1570 rtx cond, earliest, target, seq, a, b, c;
1573 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1577 /* Recognize A and B as constituting an ABS or NABS. */
1580 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1582 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1584 c = a; a = b; b = c;
1590 cond = noce_get_alt_condition (if_info, b, &earliest);
1594 /* Verify the condition is of the form we expect. */
1595 if (rtx_equal_p (XEXP (cond, 0), b))
1597 else if (rtx_equal_p (XEXP (cond, 1), b))
1602 /* Verify that C is zero. Search backward through the block for
1603 a REG_EQUAL note if necessary. */
1606 rtx insn, note = NULL;
1607 for (insn = earliest;
1608 insn != if_info->test_bb->head;
1609 insn = PREV_INSN (insn))
1611 && ((note = find_reg_note (insn, REG_EQUAL, c))
1612 || (note = find_reg_note (insn, REG_EQUIV, c))))
1618 if (GET_CODE (c) == MEM
1619 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1620 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1621 c = get_pool_constant (XEXP (c, 0));
1623 /* Work around funny ideas get_condition has wrt canonicalization.
1624 Note that these rtx constants are known to be CONST_INT, and
1625 therefore imply integer comparisons. */
1626 if (c == constm1_rtx && GET_CODE (cond) == GT)
1628 else if (c == const1_rtx && GET_CODE (cond) == LT)
1630 else if (c != CONST0_RTX (GET_MODE (b)))
1633 /* Determine what sort of operation this is. */
1634 switch (GET_CODE (cond))
1653 target = expand_abs_nojump (GET_MODE (if_info->x), b, if_info->x, 1);
1655 /* ??? It's a quandry whether cmove would be better here, especially
1656 for integers. Perhaps combine will clean things up. */
1657 if (target && negate)
1658 target = expand_simple_unop (GET_MODE (target), NEG, target, if_info->x, 0);
1666 if (target != if_info->x)
1667 noce_emit_move_insn (if_info->x, target);
1672 if (seq_contains_jump (seq))
1675 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1676 if_info->cond = cond;
1677 if_info->cond_earliest = earliest;
1682 /* Similar to get_condition, only the resulting condition must be
1683 valid at JUMP, instead of at EARLIEST. */
1686 noce_get_condition (rtx jump, rtx *earliest)
1688 rtx cond, set, tmp, insn;
1691 if (! any_condjump_p (jump))
1694 set = pc_set (jump);
1696 /* If this branches to JUMP_LABEL when the condition is false,
1697 reverse the condition. */
1698 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1699 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
1701 /* If the condition variable is a register and is MODE_INT, accept it. */
1703 cond = XEXP (SET_SRC (set), 0);
1704 tmp = XEXP (cond, 0);
1705 if (REG_P (tmp) && GET_MODE_CLASS (GET_MODE (tmp)) == MODE_INT)
1710 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
1711 GET_MODE (cond), tmp, XEXP (cond, 1));
1715 /* Otherwise, fall back on canonicalize_condition to do the dirty
1716 work of manipulating MODE_CC values and COMPARE rtx codes. */
1718 tmp = canonicalize_condition (jump, cond, reverse, earliest, NULL_RTX,
1723 /* We are going to insert code before JUMP, not before EARLIEST.
1724 We must therefore be certain that the given condition is valid
1725 at JUMP by virtue of not having been modified since. */
1726 for (insn = *earliest; insn != jump; insn = NEXT_INSN (insn))
1727 if (INSN_P (insn) && modified_in_p (tmp, insn))
1732 /* The condition was modified. See if we can get a partial result
1733 that doesn't follow all the reversals. Perhaps combine can fold
1734 them together later. */
1735 tmp = XEXP (tmp, 0);
1736 if (!REG_P (tmp) || GET_MODE_CLASS (GET_MODE (tmp)) != MODE_INT)
1738 tmp = canonicalize_condition (jump, cond, reverse, earliest, tmp,
1743 /* For sanity's sake, re-validate the new result. */
1744 for (insn = *earliest; insn != jump; insn = NEXT_INSN (insn))
1745 if (INSN_P (insn) && modified_in_p (tmp, insn))
1751 /* Return true if OP is ok for if-then-else processing. */
1754 noce_operand_ok (rtx op)
1756 /* We special-case memories, so handle any of them with
1757 no address side effects. */
1758 if (GET_CODE (op) == MEM)
1759 return ! side_effects_p (XEXP (op, 0));
1761 if (side_effects_p (op))
1764 return ! may_trap_p (op);
1767 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1768 without using conditional execution. Return TRUE if we were
1769 successful at converting the block. */
1772 noce_process_if_block (struct ce_if_block * ce_info)
1774 basic_block test_bb = ce_info->test_bb; /* test block */
1775 basic_block then_bb = ce_info->then_bb; /* THEN */
1776 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
1777 struct noce_if_info if_info;
1780 rtx orig_x, x, a, b;
1783 /* We're looking for patterns of the form
1785 (1) if (...) x = a; else x = b;
1786 (2) x = b; if (...) x = a;
1787 (3) if (...) x = a; // as if with an initial x = x.
1789 The later patterns require jumps to be more expensive.
1791 ??? For future expansion, look for multiple X in such patterns. */
1793 /* If test is comprised of && or || elements, don't handle it unless it is
1794 the special case of && elements without an ELSE block. */
1795 if (ce_info->num_multiple_test_blocks)
1797 if (else_bb || ! ce_info->and_and_p)
1800 ce_info->test_bb = test_bb = ce_info->last_test_bb;
1801 ce_info->num_multiple_test_blocks = 0;
1802 ce_info->num_and_and_blocks = 0;
1803 ce_info->num_or_or_blocks = 0;
1806 /* If this is not a standard conditional jump, we can't parse it. */
1807 jump = test_bb->end;
1808 cond = noce_get_condition (jump, &if_info.cond_earliest);
1812 /* If the conditional jump is more than just a conditional
1813 jump, then we can not do if-conversion on this block. */
1814 if (! onlyjump_p (jump))
1817 /* We must be comparing objects whose modes imply the size. */
1818 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
1821 /* Look for one of the potential sets. */
1822 insn_a = first_active_insn (then_bb);
1824 || insn_a != last_active_insn (then_bb, FALSE)
1825 || (set_a = single_set (insn_a)) == NULL_RTX)
1828 x = SET_DEST (set_a);
1829 a = SET_SRC (set_a);
1831 /* Look for the other potential set. Make sure we've got equivalent
1833 /* ??? This is overconservative. Storing to two different mems is
1834 as easy as conditionally computing the address. Storing to a
1835 single mem merely requires a scratch memory to use as one of the
1836 destination addresses; often the memory immediately below the
1837 stack pointer is available for this. */
1841 insn_b = first_active_insn (else_bb);
1843 || insn_b != last_active_insn (else_bb, FALSE)
1844 || (set_b = single_set (insn_b)) == NULL_RTX
1845 || ! rtx_equal_p (x, SET_DEST (set_b)))
1850 insn_b = prev_nonnote_insn (if_info.cond_earliest);
1851 /* We're going to be moving the evaluation of B down from above
1852 COND_EARLIEST to JUMP. Make sure the relevant data is still
1855 || GET_CODE (insn_b) != INSN
1856 || (set_b = single_set (insn_b)) == NULL_RTX
1857 || ! rtx_equal_p (x, SET_DEST (set_b))
1858 || reg_overlap_mentioned_p (x, SET_SRC (set_b))
1859 || modified_between_p (SET_SRC (set_b),
1860 PREV_INSN (if_info.cond_earliest), jump)
1861 /* Likewise with X. In particular this can happen when
1862 noce_get_condition looks farther back in the instruction
1863 stream than one might expect. */
1864 || reg_overlap_mentioned_p (x, cond)
1865 || reg_overlap_mentioned_p (x, a)
1866 || modified_between_p (x, PREV_INSN (if_info.cond_earliest), jump))
1867 insn_b = set_b = NULL_RTX;
1870 /* If x has side effects then only the if-then-else form is safe to
1871 convert. But even in that case we would need to restore any notes
1872 (such as REG_INC) at then end. That can be tricky if
1873 noce_emit_move_insn expands to more than one insn, so disable the
1874 optimization entirely for now if there are side effects. */
1875 if (side_effects_p (x))
1878 b = (set_b ? SET_SRC (set_b) : x);
1880 /* Only operate on register destinations, and even then avoid extending
1881 the lifetime of hard registers on small register class machines. */
1883 if (GET_CODE (x) != REG
1884 || (SMALL_REGISTER_CLASSES
1885 && REGNO (x) < FIRST_PSEUDO_REGISTER))
1887 if (no_new_pseudos || GET_MODE (x) == BLKmode)
1889 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
1890 ? XEXP (x, 0) : x));
1893 /* Don't operate on sources that may trap or are volatile. */
1894 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
1897 /* Set up the info block for our subroutines. */
1898 if_info.test_bb = test_bb;
1899 if_info.cond = cond;
1900 if_info.jump = jump;
1901 if_info.insn_a = insn_a;
1902 if_info.insn_b = insn_b;
1907 /* Try optimizations in some approximation of a useful order. */
1908 /* ??? Should first look to see if X is live incoming at all. If it
1909 isn't, we don't need anything but an unconditional set. */
1911 /* Look and see if A and B are really the same. Avoid creating silly
1912 cmove constructs that no one will fix up later. */
1913 if (rtx_equal_p (a, b))
1915 /* If we have an INSN_B, we don't have to create any new rtl. Just
1916 move the instruction that we already have. If we don't have an
1917 INSN_B, that means that A == X, and we've got a noop move. In
1918 that case don't do anything and let the code below delete INSN_A. */
1919 if (insn_b && else_bb)
1923 if (else_bb && insn_b == else_bb->end)
1924 else_bb->end = PREV_INSN (insn_b);
1925 reorder_insns (insn_b, insn_b, PREV_INSN (jump));
1927 /* If there was a REG_EQUAL note, delete it since it may have been
1928 true due to this insn being after a jump. */
1929 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
1930 remove_note (insn_b, note);
1934 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
1935 x must be executed twice. */
1936 else if (insn_b && side_effects_p (orig_x))
1943 if (noce_try_move (&if_info))
1945 if (noce_try_store_flag (&if_info))
1947 if (noce_try_minmax (&if_info))
1949 if (noce_try_abs (&if_info))
1951 if (HAVE_conditional_move
1952 && noce_try_cmove (&if_info))
1954 if (! HAVE_conditional_execution)
1956 if (noce_try_store_flag_constants (&if_info))
1958 if (noce_try_addcc (&if_info))
1960 if (noce_try_store_flag_mask (&if_info))
1962 if (HAVE_conditional_move
1963 && noce_try_cmove_arith (&if_info))
1970 /* The original sets may now be killed. */
1971 delete_insn (insn_a);
1973 /* Several special cases here: First, we may have reused insn_b above,
1974 in which case insn_b is now NULL. Second, we want to delete insn_b
1975 if it came from the ELSE block, because follows the now correct
1976 write that appears in the TEST block. However, if we got insn_b from
1977 the TEST block, it may in fact be loading data needed for the comparison.
1978 We'll let life_analysis remove the insn if it's really dead. */
1979 if (insn_b && else_bb)
1980 delete_insn (insn_b);
1982 /* The new insns will have been inserted immediately before the jump. We
1983 should be able to remove the jump with impunity, but the condition itself
1984 may have been modified by gcse to be shared across basic blocks. */
1987 /* If we used a temporary, fix it up now. */
1991 noce_emit_move_insn (copy_rtx (orig_x), x);
1992 insn_b = get_insns ();
1995 emit_insn_after_setloc (insn_b, test_bb->end, INSN_LOCATOR (insn_a));
1998 /* Merge the blocks! */
1999 merge_if_block (ce_info);
2004 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2005 straight line code. Return true if successful. */
2008 process_if_block (struct ce_if_block * ce_info)
2010 if (! reload_completed
2011 && noce_process_if_block (ce_info))
2014 if (HAVE_conditional_execution && reload_completed)
2016 /* If we have && and || tests, try to first handle combining the && and
2017 || tests into the conditional code, and if that fails, go back and
2018 handle it without the && and ||, which at present handles the && case
2019 if there was no ELSE block. */
2020 if (cond_exec_process_if_block (ce_info, TRUE))
2023 if (ce_info->num_multiple_test_blocks)
2027 if (cond_exec_process_if_block (ce_info, FALSE))
2035 /* Merge the blocks and mark for local life update. */
2038 merge_if_block (struct ce_if_block * ce_info)
2040 basic_block test_bb = ce_info->test_bb; /* last test block */
2041 basic_block then_bb = ce_info->then_bb; /* THEN */
2042 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2043 basic_block join_bb = ce_info->join_bb; /* join block */
2044 basic_block combo_bb;
2046 /* All block merging is done into the lower block numbers. */
2050 /* Merge any basic blocks to handle && and || subtests. Each of
2051 the blocks are on the fallthru path from the predecessor block. */
2052 if (ce_info->num_multiple_test_blocks > 0)
2054 basic_block bb = test_bb;
2055 basic_block last_test_bb = ce_info->last_test_bb;
2056 basic_block fallthru = block_fallthru (bb);
2061 fallthru = block_fallthru (bb);
2062 if (post_dominators)
2063 delete_from_dominance_info (post_dominators, bb);
2064 merge_blocks (combo_bb, bb);
2067 while (bb != last_test_bb);
2070 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2071 label, but it might if there were || tests. That label's count should be
2072 zero, and it normally should be removed. */
2076 if (combo_bb->global_live_at_end)
2077 COPY_REG_SET (combo_bb->global_live_at_end,
2078 then_bb->global_live_at_end);
2079 if (post_dominators)
2080 delete_from_dominance_info (post_dominators, then_bb);
2081 merge_blocks (combo_bb, then_bb);
2085 /* The ELSE block, if it existed, had a label. That label count
2086 will almost always be zero, but odd things can happen when labels
2087 get their addresses taken. */
2090 if (post_dominators)
2091 delete_from_dominance_info (post_dominators, else_bb);
2092 merge_blocks (combo_bb, else_bb);
2096 /* If there was no join block reported, that means it was not adjacent
2097 to the others, and so we cannot merge them. */
2101 rtx last = combo_bb->end;
2103 /* The outgoing edge for the current COMBO block should already
2104 be correct. Verify this. */
2105 if (combo_bb->succ == NULL_EDGE)
2107 if (find_reg_note (last, REG_NORETURN, NULL))
2109 else if (GET_CODE (last) == INSN
2110 && GET_CODE (PATTERN (last)) == TRAP_IF
2111 && TRAP_CONDITION (PATTERN (last)) == const_true_rtx)
2117 /* There should still be something at the end of the THEN or ELSE
2118 blocks taking us to our final destination. */
2119 else if (GET_CODE (last) == JUMP_INSN)
2121 else if (combo_bb->succ->dest == EXIT_BLOCK_PTR
2122 && GET_CODE (last) == CALL_INSN
2123 && SIBLING_CALL_P (last))
2125 else if ((combo_bb->succ->flags & EDGE_EH)
2126 && can_throw_internal (last))
2132 /* The JOIN block may have had quite a number of other predecessors too.
2133 Since we've already merged the TEST, THEN and ELSE blocks, we should
2134 have only one remaining edge from our if-then-else diamond. If there
2135 is more than one remaining edge, it must come from elsewhere. There
2136 may be zero incoming edges if the THEN block didn't actually join
2137 back up (as with a call to abort). */
2138 else if ((join_bb->pred == NULL
2139 || join_bb->pred->pred_next == NULL)
2140 && join_bb != EXIT_BLOCK_PTR)
2142 /* We can merge the JOIN. */
2143 if (combo_bb->global_live_at_end)
2144 COPY_REG_SET (combo_bb->global_live_at_end,
2145 join_bb->global_live_at_end);
2147 if (post_dominators)
2148 delete_from_dominance_info (post_dominators, join_bb);
2149 merge_blocks (combo_bb, join_bb);
2154 /* We cannot merge the JOIN. */
2156 /* The outgoing edge for the current COMBO block should already
2157 be correct. Verify this. */
2158 if (combo_bb->succ->succ_next != NULL_EDGE
2159 || combo_bb->succ->dest != join_bb)
2162 /* Remove the jump and cruft from the end of the COMBO block. */
2163 if (join_bb != EXIT_BLOCK_PTR)
2164 tidy_fallthru_edge (combo_bb->succ, combo_bb, join_bb);
2167 num_updated_if_blocks++;
2170 /* Find a block ending in a simple IF condition and try to transform it
2171 in some way. When converting a multi-block condition, put the new code
2172 in the first such block and delete the rest. Return a pointer to this
2173 first block if some transformation was done. Return NULL otherwise. */
2176 find_if_header (basic_block test_bb, int pass)
2178 ce_if_block_t ce_info;
2182 /* The kind of block we're looking for has exactly two successors. */
2183 if ((then_edge = test_bb->succ) == NULL_EDGE
2184 || (else_edge = then_edge->succ_next) == NULL_EDGE
2185 || else_edge->succ_next != NULL_EDGE)
2188 /* Neither edge should be abnormal. */
2189 if ((then_edge->flags & EDGE_COMPLEX)
2190 || (else_edge->flags & EDGE_COMPLEX))
2193 /* Nor exit the loop. */
2194 if ((then_edge->flags & EDGE_LOOP_EXIT)
2195 || (else_edge->flags & EDGE_LOOP_EXIT))
2198 /* The THEN edge is canonically the one that falls through. */
2199 if (then_edge->flags & EDGE_FALLTHRU)
2201 else if (else_edge->flags & EDGE_FALLTHRU)
2204 else_edge = then_edge;
2208 /* Otherwise this must be a multiway branch of some sort. */
2211 memset (&ce_info, '\0', sizeof (ce_info));
2212 ce_info.test_bb = test_bb;
2213 ce_info.then_bb = then_edge->dest;
2214 ce_info.else_bb = else_edge->dest;
2215 ce_info.pass = pass;
2217 #ifdef IFCVT_INIT_EXTRA_FIELDS
2218 IFCVT_INIT_EXTRA_FIELDS (&ce_info);
2221 if (find_if_block (&ce_info))
2224 if (HAVE_trap && HAVE_conditional_trap
2225 && find_cond_trap (test_bb, then_edge, else_edge))
2229 && (! HAVE_conditional_execution || reload_completed))
2231 if (find_if_case_1 (test_bb, then_edge, else_edge))
2233 if (find_if_case_2 (test_bb, then_edge, else_edge))
2241 fprintf (rtl_dump_file, "Conversion succeeded on pass %d.\n", pass);
2242 return ce_info.test_bb;
2245 /* Return true if a block has two edges, one of which falls through to the next
2246 block, and the other jumps to a specific block, so that we can tell if the
2247 block is part of an && test or an || test. Returns either -1 or the number
2248 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2251 block_jumps_and_fallthru_p (basic_block cur_bb, basic_block target_bb)
2254 int fallthru_p = FALSE;
2260 if (!cur_bb || !target_bb)
2263 /* If no edges, obviously it doesn't jump or fallthru. */
2264 if (cur_bb->succ == NULL_EDGE)
2267 for (cur_edge = cur_bb->succ;
2268 cur_edge != NULL_EDGE;
2269 cur_edge = cur_edge->succ_next)
2271 if (cur_edge->flags & EDGE_COMPLEX)
2272 /* Anything complex isn't what we want. */
2275 else if (cur_edge->flags & EDGE_FALLTHRU)
2278 else if (cur_edge->dest == target_bb)
2285 if ((jump_p & fallthru_p) == 0)
2288 /* Don't allow calls in the block, since this is used to group && and ||
2289 together for conditional execution support. ??? we should support
2290 conditional execution support across calls for IA-64 some day, but
2291 for now it makes the code simpler. */
2293 insn = cur_bb->head;
2295 while (insn != NULL_RTX)
2297 if (GET_CODE (insn) == CALL_INSN)
2301 && GET_CODE (insn) != JUMP_INSN
2302 && GET_CODE (PATTERN (insn)) != USE
2303 && GET_CODE (PATTERN (insn)) != CLOBBER)
2309 insn = NEXT_INSN (insn);
2315 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2316 block. If so, we'll try to convert the insns to not require the branch.
2317 Return TRUE if we were successful at converting the block. */
2320 find_if_block (struct ce_if_block * ce_info)
2322 basic_block test_bb = ce_info->test_bb;
2323 basic_block then_bb = ce_info->then_bb;
2324 basic_block else_bb = ce_info->else_bb;
2325 basic_block join_bb = NULL_BLOCK;
2326 edge then_succ = then_bb->succ;
2327 edge else_succ = else_bb->succ;
2328 int then_predecessors;
2329 int else_predecessors;
2333 ce_info->last_test_bb = test_bb;
2335 /* Discover if any fall through predecessors of the current test basic block
2336 were && tests (which jump to the else block) or || tests (which jump to
2338 if (HAVE_conditional_execution && reload_completed
2339 && test_bb->pred != NULL_EDGE
2340 && test_bb->pred->pred_next == NULL_EDGE
2341 && test_bb->pred->flags == EDGE_FALLTHRU)
2343 basic_block bb = test_bb->pred->src;
2344 basic_block target_bb;
2345 int max_insns = MAX_CONDITIONAL_EXECUTE;
2348 /* Determine if the preceding block is an && or || block. */
2349 if ((n_insns = block_jumps_and_fallthru_p (bb, else_bb)) >= 0)
2351 ce_info->and_and_p = TRUE;
2352 target_bb = else_bb;
2354 else if ((n_insns = block_jumps_and_fallthru_p (bb, then_bb)) >= 0)
2356 ce_info->and_and_p = FALSE;
2357 target_bb = then_bb;
2360 target_bb = NULL_BLOCK;
2362 if (target_bb && n_insns <= max_insns)
2364 int total_insns = 0;
2367 ce_info->last_test_bb = test_bb;
2369 /* Found at least one && or || block, look for more. */
2372 ce_info->test_bb = test_bb = bb;
2373 total_insns += n_insns;
2376 if (bb->pred == NULL_EDGE || bb->pred->pred_next != NULL_EDGE)
2380 n_insns = block_jumps_and_fallthru_p (bb, target_bb);
2382 while (n_insns >= 0 && (total_insns + n_insns) <= max_insns);
2384 ce_info->num_multiple_test_blocks = blocks;
2385 ce_info->num_multiple_test_insns = total_insns;
2387 if (ce_info->and_and_p)
2388 ce_info->num_and_and_blocks = blocks;
2390 ce_info->num_or_or_blocks = blocks;
2394 /* Count the number of edges the THEN and ELSE blocks have. */
2395 then_predecessors = 0;
2396 for (cur_edge = then_bb->pred;
2397 cur_edge != NULL_EDGE;
2398 cur_edge = cur_edge->pred_next)
2400 then_predecessors++;
2401 if (cur_edge->flags & EDGE_COMPLEX)
2405 else_predecessors = 0;
2406 for (cur_edge = else_bb->pred;
2407 cur_edge != NULL_EDGE;
2408 cur_edge = cur_edge->pred_next)
2410 else_predecessors++;
2411 if (cur_edge->flags & EDGE_COMPLEX)
2415 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2416 other than any || blocks which jump to the THEN block. */
2417 if ((then_predecessors - ce_info->num_or_or_blocks) != 1)
2420 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2421 if (then_succ != NULL_EDGE
2422 && (then_succ->succ_next != NULL_EDGE
2423 || (then_succ->flags & EDGE_COMPLEX)
2424 || (flow2_completed && tablejump_p (then_bb->end, NULL, NULL))))
2427 /* If the THEN block has no successors, conditional execution can still
2428 make a conditional call. Don't do this unless the ELSE block has
2429 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2430 Check for the last insn of the THEN block being an indirect jump, which
2431 is listed as not having any successors, but confuses the rest of the CE
2432 code processing. ??? we should fix this in the future. */
2433 if (then_succ == NULL)
2435 if (else_bb->pred->pred_next == NULL_EDGE)
2437 rtx last_insn = then_bb->end;
2440 && GET_CODE (last_insn) == NOTE
2441 && last_insn != then_bb->head)
2442 last_insn = PREV_INSN (last_insn);
2445 && GET_CODE (last_insn) == JUMP_INSN
2446 && ! simplejump_p (last_insn))
2450 else_bb = NULL_BLOCK;
2456 /* If the THEN block's successor is the other edge out of the TEST block,
2457 then we have an IF-THEN combo without an ELSE. */
2458 else if (then_succ->dest == else_bb)
2461 else_bb = NULL_BLOCK;
2464 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2465 has exactly one predecessor and one successor, and the outgoing edge
2466 is not complex, then we have an IF-THEN-ELSE combo. */
2467 else if (else_succ != NULL_EDGE
2468 && then_succ->dest == else_succ->dest
2469 && else_bb->pred->pred_next == NULL_EDGE
2470 && else_succ->succ_next == NULL_EDGE
2471 && ! (else_succ->flags & EDGE_COMPLEX)
2472 && ! (flow2_completed && tablejump_p (else_bb->end, NULL, NULL)))
2473 join_bb = else_succ->dest;
2475 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2479 num_possible_if_blocks++;
2483 fprintf (rtl_dump_file, "\nIF-THEN%s block found, pass %d, start block %d [insn %d], then %d [%d]",
2484 (else_bb) ? "-ELSE" : "",
2486 test_bb->index, (test_bb->head) ? (int)INSN_UID (test_bb->head) : -1,
2487 then_bb->index, (then_bb->head) ? (int)INSN_UID (then_bb->head) : -1);
2490 fprintf (rtl_dump_file, ", else %d [%d]",
2491 else_bb->index, (else_bb->head) ? (int)INSN_UID (else_bb->head) : -1);
2493 fprintf (rtl_dump_file, ", join %d [%d]",
2494 join_bb->index, (join_bb->head) ? (int)INSN_UID (join_bb->head) : -1);
2496 if (ce_info->num_multiple_test_blocks > 0)
2497 fprintf (rtl_dump_file, ", %d %s block%s last test %d [%d]",
2498 ce_info->num_multiple_test_blocks,
2499 (ce_info->and_and_p) ? "&&" : "||",
2500 (ce_info->num_multiple_test_blocks == 1) ? "" : "s",
2501 ce_info->last_test_bb->index,
2502 ((ce_info->last_test_bb->head)
2503 ? (int)INSN_UID (ce_info->last_test_bb->head)
2506 fputc ('\n', rtl_dump_file);
2509 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2510 first condition for free, since we've already asserted that there's a
2511 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2512 we checked the FALLTHRU flag, those are already adjacent to the last IF
2514 /* ??? As an enhancement, move the ELSE block. Have to deal with
2515 BLOCK notes, if by no other means than aborting the merge if they
2516 exist. Sticky enough I don't want to think about it now. */
2518 if (else_bb && (next = next->next_bb) != else_bb)
2520 if ((next = next->next_bb) != join_bb && join_bb != EXIT_BLOCK_PTR)
2528 /* Do the real work. */
2529 ce_info->else_bb = else_bb;
2530 ce_info->join_bb = join_bb;
2532 return process_if_block (ce_info);
2535 /* Convert a branch over a trap, or a branch
2536 to a trap, into a conditional trap. */
2539 find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
2541 basic_block then_bb = then_edge->dest;
2542 basic_block else_bb = else_edge->dest;
2543 basic_block other_bb, trap_bb;
2544 rtx trap, jump, cond, cond_earliest, seq;
2547 /* Locate the block with the trap instruction. */
2548 /* ??? While we look for no successors, we really ought to allow
2549 EH successors. Need to fix merge_if_block for that to work. */
2550 if ((trap = block_has_only_trap (then_bb)) != NULL)
2551 trap_bb = then_bb, other_bb = else_bb;
2552 else if ((trap = block_has_only_trap (else_bb)) != NULL)
2553 trap_bb = else_bb, other_bb = then_bb;
2559 fprintf (rtl_dump_file, "\nTRAP-IF block found, start %d, trap %d\n",
2560 test_bb->index, trap_bb->index);
2563 /* If this is not a standard conditional jump, we can't parse it. */
2564 jump = test_bb->end;
2565 cond = noce_get_condition (jump, &cond_earliest);
2569 /* If the conditional jump is more than just a conditional jump, then
2570 we can not do if-conversion on this block. */
2571 if (! onlyjump_p (jump))
2574 /* We must be comparing objects whose modes imply the size. */
2575 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2578 /* Reverse the comparison code, if necessary. */
2579 code = GET_CODE (cond);
2580 if (then_bb == trap_bb)
2582 code = reversed_comparison_code (cond, jump);
2583 if (code == UNKNOWN)
2587 /* Attempt to generate the conditional trap. */
2588 seq = gen_cond_trap (code, XEXP (cond, 0), XEXP (cond, 1),
2589 TRAP_CODE (PATTERN (trap)));
2595 /* Emit the new insns before cond_earliest. */
2596 emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
2598 /* Delete the trap block if possible. */
2599 remove_edge (trap_bb == then_bb ? then_edge : else_edge);
2600 if (trap_bb->pred == NULL)
2602 if (post_dominators)
2603 delete_from_dominance_info (post_dominators, trap_bb);
2604 delete_block (trap_bb);
2607 /* If the non-trap block and the test are now adjacent, merge them.
2608 Otherwise we must insert a direct branch. */
2609 if (test_bb->next_bb == other_bb)
2611 struct ce_if_block new_ce_info;
2613 memset (&new_ce_info, '\0', sizeof (new_ce_info));
2614 new_ce_info.test_bb = test_bb;
2615 new_ce_info.then_bb = NULL;
2616 new_ce_info.else_bb = NULL;
2617 new_ce_info.join_bb = other_bb;
2618 merge_if_block (&new_ce_info);
2624 lab = JUMP_LABEL (jump);
2625 newjump = emit_jump_insn_after (gen_jump (lab), jump);
2626 LABEL_NUSES (lab) += 1;
2627 JUMP_LABEL (newjump) = lab;
2628 emit_barrier_after (newjump);
2636 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2640 block_has_only_trap (basic_block bb)
2644 /* We're not the exit block. */
2645 if (bb == EXIT_BLOCK_PTR)
2648 /* The block must have no successors. */
2652 /* The only instruction in the THEN block must be the trap. */
2653 trap = first_active_insn (bb);
2654 if (! (trap == bb->end
2655 && GET_CODE (PATTERN (trap)) == TRAP_IF
2656 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
2662 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2663 transformable, but not necessarily the other. There need be no
2666 Return TRUE if we were successful at converting the block.
2668 Cases we'd like to look at:
2671 if (test) goto over; // x not live
2679 if (! test) goto label;
2682 if (test) goto E; // x not live
2696 (3) // This one's really only interesting for targets that can do
2697 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2698 // it results in multiple branches on a cache line, which often
2699 // does not sit well with predictors.
2701 if (test1) goto E; // predicted not taken
2717 (A) Don't do (2) if the branch is predicted against the block we're
2718 eliminating. Do it anyway if we can eliminate a branch; this requires
2719 that the sole successor of the eliminated block postdominate the other
2722 (B) With CE, on (3) we can steal from both sides of the if, creating
2731 Again, this is most useful if J postdominates.
2733 (C) CE substitutes for helpful life information.
2735 (D) These heuristics need a lot of work. */
2737 /* Tests for case 1 above. */
2740 find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
2742 basic_block then_bb = then_edge->dest;
2743 basic_block else_bb = else_edge->dest, new_bb;
2744 edge then_succ = then_bb->succ;
2747 /* THEN has one successor. */
2748 if (!then_succ || then_succ->succ_next != NULL)
2751 /* THEN does not fall through, but is not strange either. */
2752 if (then_succ->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
2755 /* THEN has one predecessor. */
2756 if (then_bb->pred->pred_next != NULL)
2759 /* THEN must do something. */
2760 if (forwarder_block_p (then_bb))
2763 num_possible_if_blocks++;
2765 fprintf (rtl_dump_file,
2766 "\nIF-CASE-1 found, start %d, then %d\n",
2767 test_bb->index, then_bb->index);
2769 /* THEN is small. */
2770 if (count_bb_insns (then_bb) > BRANCH_COST)
2773 /* Registers set are dead, or are predicable. */
2774 if (! dead_or_predicable (test_bb, then_bb, else_bb,
2775 then_bb->succ->dest, 1))
2778 /* Conversion went ok, including moving the insns and fixing up the
2779 jump. Adjust the CFG to match. */
2781 bitmap_operation (test_bb->global_live_at_end,
2782 else_bb->global_live_at_start,
2783 then_bb->global_live_at_end, BITMAP_IOR);
2785 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb), else_bb);
2786 then_bb_index = then_bb->index;
2787 if (post_dominators)
2788 delete_from_dominance_info (post_dominators, then_bb);
2789 delete_block (then_bb);
2791 /* Make rest of code believe that the newly created block is the THEN_BB
2792 block we removed. */
2795 new_bb->index = then_bb_index;
2796 BASIC_BLOCK (then_bb_index) = new_bb;
2797 if (post_dominators)
2798 add_to_dominance_info (post_dominators, new_bb);
2800 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2804 num_updated_if_blocks++;
2809 /* Test for case 2 above. */
2812 find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
2814 basic_block then_bb = then_edge->dest;
2815 basic_block else_bb = else_edge->dest;
2816 edge else_succ = else_bb->succ;
2819 /* ELSE has one successor. */
2820 if (!else_succ || else_succ->succ_next != NULL)
2823 /* ELSE outgoing edge is not complex. */
2824 if (else_succ->flags & EDGE_COMPLEX)
2827 /* ELSE has one predecessor. */
2828 if (else_bb->pred->pred_next != NULL)
2831 /* THEN is not EXIT. */
2832 if (then_bb->index < 0)
2835 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2836 note = find_reg_note (test_bb->end, REG_BR_PROB, NULL_RTX);
2837 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
2839 else if (else_succ->dest->index < 0
2840 || dominated_by_p (post_dominators, then_bb,
2846 num_possible_if_blocks++;
2848 fprintf (rtl_dump_file,
2849 "\nIF-CASE-2 found, start %d, else %d\n",
2850 test_bb->index, else_bb->index);
2852 /* ELSE is small. */
2853 if (count_bb_insns (else_bb) > BRANCH_COST)
2856 /* Registers set are dead, or are predicable. */
2857 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
2860 /* Conversion went ok, including moving the insns and fixing up the
2861 jump. Adjust the CFG to match. */
2863 bitmap_operation (test_bb->global_live_at_end,
2864 then_bb->global_live_at_start,
2865 else_bb->global_live_at_end, BITMAP_IOR);
2867 if (post_dominators)
2868 delete_from_dominance_info (post_dominators, else_bb);
2869 delete_block (else_bb);
2872 num_updated_if_blocks++;
2874 /* ??? We may now fallthru from one of THEN's successors into a join
2875 block. Rerun cleanup_cfg? Examine things manually? Wait? */
2880 /* A subroutine of dead_or_predicable called through for_each_rtx.
2881 Return 1 if a memory is found. */
2884 find_memory (rtx *px, void *data ATTRIBUTE_UNUSED)
2886 return GET_CODE (*px) == MEM;
2889 /* Used by the code above to perform the actual rtl transformations.
2890 Return TRUE if successful.
2892 TEST_BB is the block containing the conditional branch. MERGE_BB
2893 is the block containing the code to manipulate. NEW_DEST is the
2894 label TEST_BB should be branching to after the conversion.
2895 REVERSEP is true if the sense of the branch should be reversed. */
2898 dead_or_predicable (basic_block test_bb, basic_block merge_bb,
2899 basic_block other_bb, basic_block new_dest, int reversep)
2901 rtx head, end, jump, earliest, old_dest, new_label = NULL_RTX;
2903 jump = test_bb->end;
2905 /* Find the extent of the real code in the merge block. */
2906 head = merge_bb->head;
2907 end = merge_bb->end;
2909 if (GET_CODE (head) == CODE_LABEL)
2910 head = NEXT_INSN (head);
2911 if (GET_CODE (head) == NOTE)
2915 head = end = NULL_RTX;
2918 head = NEXT_INSN (head);
2921 if (GET_CODE (end) == JUMP_INSN)
2925 head = end = NULL_RTX;
2928 end = PREV_INSN (end);
2931 /* Disable handling dead code by conditional execution if the machine needs
2932 to do anything funny with the tests, etc. */
2933 #ifndef IFCVT_MODIFY_TESTS
2934 if (HAVE_conditional_execution)
2936 /* In the conditional execution case, we have things easy. We know
2937 the condition is reversible. We don't have to check life info,
2938 becase we're going to conditionally execute the code anyway.
2939 All that's left is making sure the insns involved can actually
2944 cond = cond_exec_get_condition (jump);
2948 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
2950 prob_val = XEXP (prob_val, 0);
2954 enum rtx_code rev = reversed_comparison_code (cond, jump);
2957 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
2960 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
2963 if (! cond_exec_process_insns ((ce_if_block_t *)0, head, end, cond,
2972 /* In the non-conditional execution case, we have to verify that there
2973 are no trapping operations, no calls, no references to memory, and
2974 that any registers modified are dead at the branch site. */
2976 rtx insn, cond, prev;
2977 regset_head merge_set_head, tmp_head, test_live_head, test_set_head;
2978 regset merge_set, tmp, test_live, test_set;
2979 struct propagate_block_info *pbi;
2982 /* Check for no calls or trapping operations. */
2983 for (insn = head; ; insn = NEXT_INSN (insn))
2985 if (GET_CODE (insn) == CALL_INSN)
2989 if (may_trap_p (PATTERN (insn)))
2992 /* ??? Even non-trapping memories such as stack frame
2993 references must be avoided. For stores, we collect
2994 no lifetime info; for reads, we'd have to assert
2995 true_dependence false against every store in the
2997 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
3004 if (! any_condjump_p (jump))
3007 /* Find the extent of the conditional. */
3008 cond = noce_get_condition (jump, &earliest);
3013 MERGE_SET = set of registers set in MERGE_BB
3014 TEST_LIVE = set of registers live at EARLIEST
3015 TEST_SET = set of registers set between EARLIEST and the
3016 end of the block. */
3018 tmp = INITIALIZE_REG_SET (tmp_head);
3019 merge_set = INITIALIZE_REG_SET (merge_set_head);
3020 test_live = INITIALIZE_REG_SET (test_live_head);
3021 test_set = INITIALIZE_REG_SET (test_set_head);
3023 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3024 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3025 since we've already asserted that MERGE_BB is small. */
3026 propagate_block (merge_bb, tmp, merge_set, merge_set, 0);
3028 /* For small register class machines, don't lengthen lifetimes of
3029 hard registers before reload. */
3030 if (SMALL_REGISTER_CLASSES && ! reload_completed)
3032 EXECUTE_IF_SET_IN_BITMAP
3035 if (i < FIRST_PSEUDO_REGISTER
3037 && ! global_regs[i])
3042 /* For TEST, we're interested in a range of insns, not a whole block.
3043 Moreover, we're interested in the insns live from OTHER_BB. */
3045 COPY_REG_SET (test_live, other_bb->global_live_at_start);
3046 pbi = init_propagate_block_info (test_bb, test_live, test_set, test_set,
3049 for (insn = jump; ; insn = prev)
3051 prev = propagate_one_insn (pbi, insn);
3052 if (insn == earliest)
3056 free_propagate_block_info (pbi);
3058 /* We can perform the transformation if
3059 MERGE_SET & (TEST_SET | TEST_LIVE)
3061 TEST_SET & merge_bb->global_live_at_start
3064 bitmap_operation (tmp, test_set, test_live, BITMAP_IOR);
3065 bitmap_operation (tmp, tmp, merge_set, BITMAP_AND);
3066 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
3068 bitmap_operation (tmp, test_set, merge_bb->global_live_at_start,
3070 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
3073 FREE_REG_SET (merge_set);
3074 FREE_REG_SET (test_live);
3075 FREE_REG_SET (test_set);
3082 /* We don't want to use normal invert_jump or redirect_jump because
3083 we don't want to delete_insn called. Also, we want to do our own
3084 change group management. */
3086 old_dest = JUMP_LABEL (jump);
3087 if (other_bb != new_dest)
3089 new_label = block_label (new_dest);
3091 ? ! invert_jump_1 (jump, new_label)
3092 : ! redirect_jump_1 (jump, new_label))
3096 if (! apply_change_group ())
3099 if (other_bb != new_dest)
3102 LABEL_NUSES (old_dest) -= 1;
3104 LABEL_NUSES (new_label) += 1;
3105 JUMP_LABEL (jump) = new_label;
3107 invert_br_probabilities (jump);
3109 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
3112 gcov_type count, probability;
3113 count = BRANCH_EDGE (test_bb)->count;
3114 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
3115 FALLTHRU_EDGE (test_bb)->count = count;
3116 probability = BRANCH_EDGE (test_bb)->probability;
3117 BRANCH_EDGE (test_bb)->probability
3118 = FALLTHRU_EDGE (test_bb)->probability;
3119 FALLTHRU_EDGE (test_bb)->probability = probability;
3120 update_br_prob_note (test_bb);
3124 /* Move the insns out of MERGE_BB to before the branch. */
3127 if (end == merge_bb->end)
3128 merge_bb->end = PREV_INSN (head);
3130 if (squeeze_notes (&head, &end))
3133 reorder_insns (head, end, PREV_INSN (earliest));
3136 /* Remove the jump and edge if we can. */
3137 if (other_bb == new_dest)
3140 remove_edge (BRANCH_EDGE (test_bb));
3141 /* ??? Can't merge blocks here, as then_bb is still in use.
3142 At minimum, the merge will get done just before bb-reorder. */
3152 /* Main entry point for all if-conversion. */
3155 if_convert (int x_life_data_ok)
3160 num_possible_if_blocks = 0;
3161 num_updated_if_blocks = 0;
3162 num_true_changes = 0;
3163 life_data_ok = (x_life_data_ok != 0);
3165 if (! (* targetm.cannot_modify_jumps_p) ())
3166 mark_loop_exit_edges ();
3168 /* Free up basic_block_for_insn so that we don't have to keep it
3169 up to date, either here or in merge_blocks. */
3170 free_basic_block_vars (1);
3172 /* Compute postdominators if we think we'll use them. */
3173 post_dominators = NULL;
3174 if (HAVE_conditional_execution || life_data_ok)
3176 post_dominators = calculate_dominance_info (CDI_POST_DOMINATORS);
3181 /* Go through each of the basic blocks looking for things to convert. If we
3182 have conditional execution, we make multiple passes to allow us to handle
3183 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3187 cond_exec_changed_p = FALSE;
3190 #ifdef IFCVT_MULTIPLE_DUMPS
3191 if (rtl_dump_file && pass > 1)
3192 fprintf (rtl_dump_file, "\n\n========== Pass %d ==========\n", pass);
3198 while ((new_bb = find_if_header (bb, pass)))
3202 #ifdef IFCVT_MULTIPLE_DUMPS
3203 if (rtl_dump_file && cond_exec_changed_p)
3204 print_rtl_with_bb (rtl_dump_file, get_insns ());
3207 while (cond_exec_changed_p);
3209 #ifdef IFCVT_MULTIPLE_DUMPS
3211 fprintf (rtl_dump_file, "\n\n========== no more changes\n");
3214 if (post_dominators)
3215 free_dominance_info (post_dominators);
3218 fflush (rtl_dump_file);
3220 clear_aux_for_blocks ();
3222 /* Rebuild life info for basic blocks that require it. */
3223 if (num_true_changes && life_data_ok)
3225 /* If we allocated new pseudos, we must resize the array for sched1. */
3226 if (max_regno < max_reg_num ())
3228 max_regno = max_reg_num ();
3229 allocate_reg_info (max_regno, FALSE, FALSE);
3231 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES,
3232 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
3233 | PROP_KILL_DEAD_CODE);
3236 /* Write the final stats. */
3237 if (rtl_dump_file && num_possible_if_blocks > 0)
3239 fprintf (rtl_dump_file,
3240 "\n%d possible IF blocks searched.\n",
3241 num_possible_if_blocks);
3242 fprintf (rtl_dump_file,
3243 "%d IF blocks converted.\n",
3244 num_updated_if_blocks);
3245 fprintf (rtl_dump_file,
3246 "%d true changes made.\n\n\n",
3250 #ifdef ENABLE_CHECKING
3251 verify_flow_info ();