1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GCC is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
15 License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
24 #include "coretypes.h"
31 #include "insn-config.h"
34 #include "hard-reg-set.h"
35 #include "basic-block.h"
45 #include "tree-pass.h"
48 #ifndef HAVE_conditional_execution
49 #define HAVE_conditional_execution 0
51 #ifndef HAVE_conditional_move
52 #define HAVE_conditional_move 0
63 #ifndef HAVE_conditional_trap
64 #define HAVE_conditional_trap 0
67 #ifndef MAX_CONDITIONAL_EXECUTE
68 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
71 #define NULL_BLOCK ((basic_block) NULL)
73 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
74 static int num_possible_if_blocks;
76 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
78 static int num_updated_if_blocks;
80 /* # of changes made which require life information to be updated. */
81 static int num_true_changes;
83 /* Whether conditional execution changes were made. */
84 static int cond_exec_changed_p;
86 /* True if life data ok at present. */
87 static bool life_data_ok;
89 /* Forward references. */
90 static int count_bb_insns (basic_block);
91 static bool cheap_bb_rtx_cost_p (basic_block, int);
92 static rtx first_active_insn (basic_block);
93 static rtx last_active_insn (basic_block, int);
94 static basic_block block_fallthru (basic_block);
95 static int cond_exec_process_insns (ce_if_block_t *, rtx, rtx, rtx, rtx, int);
96 static rtx cond_exec_get_condition (rtx);
97 static int cond_exec_process_if_block (ce_if_block_t *, int);
98 static rtx noce_get_condition (rtx, rtx *);
99 static int noce_operand_ok (rtx);
100 static int noce_process_if_block (ce_if_block_t *);
101 static int process_if_block (ce_if_block_t *);
102 static void merge_if_block (ce_if_block_t *);
103 static int find_cond_trap (basic_block, edge, edge);
104 static basic_block find_if_header (basic_block, int);
105 static int block_jumps_and_fallthru_p (basic_block, basic_block);
106 static int find_if_block (ce_if_block_t *);
107 static int find_if_case_1 (basic_block, edge, edge);
108 static int find_if_case_2 (basic_block, edge, edge);
109 static int find_memory (rtx *, void *);
110 static int dead_or_predicable (basic_block, basic_block, basic_block,
112 static void noce_emit_move_insn (rtx, rtx);
113 static rtx block_has_only_trap (basic_block);
115 /* Count the number of non-jump active insns in BB. */
118 count_bb_insns (basic_block bb)
121 rtx insn = BB_HEAD (bb);
125 if (CALL_P (insn) || NONJUMP_INSN_P (insn))
128 if (insn == BB_END (bb))
130 insn = NEXT_INSN (insn);
136 /* Determine whether the total insn_rtx_cost on non-jump insns in
137 basic block BB is less than MAX_COST. This function returns
138 false if the cost of any instruction could not be estimated. */
141 cheap_bb_rtx_cost_p (basic_block bb, int max_cost)
144 rtx insn = BB_HEAD (bb);
148 if (NONJUMP_INSN_P (insn))
150 int cost = insn_rtx_cost (PATTERN (insn));
154 /* If this instruction is the load or set of a "stack" register,
155 such as a floating point register on x87, then the cost of
156 speculatively executing this insn may need to include
157 the additional cost of popping its result off of the
158 register stack. Unfortunately, correctly recognizing and
159 accounting for this additional overhead is tricky, so for
160 now we simply prohibit such speculative execution. */
163 rtx set = single_set (insn);
164 if (set && STACK_REG_P (SET_DEST (set)))
170 if (count >= max_cost)
173 else if (CALL_P (insn))
176 if (insn == BB_END (bb))
178 insn = NEXT_INSN (insn);
184 /* Return the first non-jump active insn in the basic block. */
187 first_active_insn (basic_block bb)
189 rtx insn = BB_HEAD (bb);
193 if (insn == BB_END (bb))
195 insn = NEXT_INSN (insn);
198 while (NOTE_P (insn))
200 if (insn == BB_END (bb))
202 insn = NEXT_INSN (insn);
211 /* Return the last non-jump active (non-jump) insn in the basic block. */
214 last_active_insn (basic_block bb, int skip_use_p)
216 rtx insn = BB_END (bb);
217 rtx head = BB_HEAD (bb);
222 && NONJUMP_INSN_P (insn)
223 && GET_CODE (PATTERN (insn)) == USE))
227 insn = PREV_INSN (insn);
236 /* Return the basic block reached by falling though the basic block BB. */
239 block_fallthru (basic_block bb)
244 FOR_EACH_EDGE (e, ei, bb->succs)
245 if (e->flags & EDGE_FALLTHRU)
248 return (e) ? e->dest : NULL_BLOCK;
251 /* Go through a bunch of insns, converting them to conditional
252 execution format if possible. Return TRUE if all of the non-note
253 insns were processed. */
256 cond_exec_process_insns (ce_if_block_t *ce_info ATTRIBUTE_UNUSED,
257 /* if block information */rtx start,
258 /* first insn to look at */rtx end,
259 /* last insn to look at */rtx test,
260 /* conditional execution test */rtx prob_val,
261 /* probability of branch taken. */int mod_ok)
263 int must_be_last = FALSE;
271 for (insn = start; ; insn = NEXT_INSN (insn))
276 gcc_assert(NONJUMP_INSN_P (insn) || CALL_P (insn));
278 /* Remove USE insns that get in the way. */
279 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
281 /* ??? Ug. Actually unlinking the thing is problematic,
282 given what we'd have to coordinate with our callers. */
283 SET_INSN_DELETED (insn);
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 (CALL_P (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 (BB_END (test_bb));
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 (BB_END (test_bb)))
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, BB_END (test_bb));
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 (BB_END (test_bb), 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;
483 enum rtx_code f_code;
485 bb = block_fallthru (bb);
486 start = first_active_insn (bb);
487 end = last_active_insn (bb, TRUE);
489 && ! cond_exec_process_insns (ce_info, start, end, false_expr,
490 false_prob_val, FALSE))
493 /* If the conditional jump is more than just a conditional jump, then
494 we can not do conditional execution conversion on this block. */
495 if (! onlyjump_p (BB_END (bb)))
498 /* Find the conditional jump and isolate the test. */
499 t = cond_exec_get_condition (BB_END (bb));
503 f_code = reversed_comparison_code (t, BB_END (bb));
504 if (f_code == UNKNOWN)
507 f = gen_rtx_fmt_ee (f_code, GET_MODE (t), XEXP (t, 0), XEXP (t, 1));
508 if (ce_info->and_and_p)
510 t = gen_rtx_AND (GET_MODE (t), true_expr, t);
511 f = gen_rtx_IOR (GET_MODE (t), false_expr, f);
515 t = gen_rtx_IOR (GET_MODE (t), true_expr, t);
516 f = gen_rtx_AND (GET_MODE (t), false_expr, f);
519 /* If the machine description needs to modify the tests, such as
520 setting a conditional execution register from a comparison, it can
522 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
523 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info, bb, t, f);
525 /* See if the conversion failed. */
533 while (bb != last_test_bb);
536 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
537 on then THEN block. */
538 then_mod_ok = (else_bb == NULL_BLOCK);
540 /* Go through the THEN and ELSE blocks converting the insns if possible
541 to conditional execution. */
545 || ! cond_exec_process_insns (ce_info, then_start, then_end,
546 false_expr, false_prob_val,
550 if (else_bb && else_end
551 && ! cond_exec_process_insns (ce_info, else_start, else_end,
552 true_expr, true_prob_val, TRUE))
555 /* If we cannot apply the changes, fail. Do not go through the normal fail
556 processing, since apply_change_group will call cancel_changes. */
557 if (! apply_change_group ())
559 #ifdef IFCVT_MODIFY_CANCEL
560 /* Cancel any machine dependent changes. */
561 IFCVT_MODIFY_CANCEL (ce_info);
566 #ifdef IFCVT_MODIFY_FINAL
567 /* Do any machine dependent final modifications. */
568 IFCVT_MODIFY_FINAL (ce_info);
571 /* Conversion succeeded. */
573 fprintf (dump_file, "%d insn%s converted to conditional execution.\n",
574 n_insns, (n_insns == 1) ? " was" : "s were");
576 /* Merge the blocks! */
577 merge_if_block (ce_info);
578 cond_exec_changed_p = TRUE;
582 #ifdef IFCVT_MODIFY_CANCEL
583 /* Cancel any machine dependent changes. */
584 IFCVT_MODIFY_CANCEL (ce_info);
591 /* Used by noce_process_if_block to communicate with its subroutines.
593 The subroutines know that A and B may be evaluated freely. They
594 know that X is a register. They should insert new instructions
595 before cond_earliest. */
602 rtx jump, cond, cond_earliest;
603 /* True if "b" was originally evaluated unconditionally. */
604 bool b_unconditional;
607 static rtx noce_emit_store_flag (struct noce_if_info *, rtx, int, int);
608 static int noce_try_move (struct noce_if_info *);
609 static int noce_try_store_flag (struct noce_if_info *);
610 static int noce_try_addcc (struct noce_if_info *);
611 static int noce_try_store_flag_constants (struct noce_if_info *);
612 static int noce_try_store_flag_mask (struct noce_if_info *);
613 static rtx noce_emit_cmove (struct noce_if_info *, rtx, enum rtx_code, rtx,
615 static int noce_try_cmove (struct noce_if_info *);
616 static int noce_try_cmove_arith (struct noce_if_info *);
617 static rtx noce_get_alt_condition (struct noce_if_info *, rtx, rtx *);
618 static int noce_try_minmax (struct noce_if_info *);
619 static int noce_try_abs (struct noce_if_info *);
620 static int noce_try_sign_mask (struct noce_if_info *);
622 /* Helper function for noce_try_store_flag*. */
625 noce_emit_store_flag (struct noce_if_info *if_info, rtx x, int reversep,
628 rtx cond = if_info->cond;
632 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
633 || ! general_operand (XEXP (cond, 1), VOIDmode));
635 /* If earliest == jump, or when the condition is complex, try to
636 build the store_flag insn directly. */
639 cond = XEXP (SET_SRC (pc_set (if_info->jump)), 0);
642 code = reversed_comparison_code (cond, if_info->jump);
644 code = GET_CODE (cond);
646 if ((if_info->cond_earliest == if_info->jump || cond_complex)
647 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
651 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
653 tmp = gen_rtx_SET (VOIDmode, x, tmp);
656 tmp = emit_insn (tmp);
658 if (recog_memoized (tmp) >= 0)
664 if_info->cond_earliest = if_info->jump;
672 /* Don't even try if the comparison operands or the mode of X are weird. */
673 if (cond_complex || !SCALAR_INT_MODE_P (GET_MODE (x)))
676 return emit_store_flag (x, code, XEXP (cond, 0),
677 XEXP (cond, 1), VOIDmode,
678 (code == LTU || code == LEU
679 || code == GEU || code == GTU), normalize);
682 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
683 X is the destination/target and Y is the value to copy. */
686 noce_emit_move_insn (rtx x, rtx y)
688 enum machine_mode outmode;
692 if (GET_CODE (x) != STRICT_LOW_PART)
694 rtx seq, insn, target;
698 /* Check that the SET_SRC is reasonable before calling emit_move_insn,
699 otherwise construct a suitable SET pattern ourselves. */
700 insn = (OBJECT_P (y) || CONSTANT_P (y) || GET_CODE (y) == SUBREG)
701 ? emit_move_insn (x, y)
702 : emit_insn (gen_rtx_SET (VOIDmode, x, y));
706 if (recog_memoized (insn) <= 0)
708 if (GET_CODE (x) == ZERO_EXTRACT)
710 rtx op = XEXP (x, 0);
711 unsigned HOST_WIDE_INT size = INTVAL (XEXP (x, 1));
712 unsigned HOST_WIDE_INT start = INTVAL (XEXP (x, 2));
714 /* store_bit_field expects START to be relative to
715 BYTES_BIG_ENDIAN and adjusts this value for machines with
716 BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN. In order to be able to
717 invoke store_bit_field again it is necessary to have the START
718 value from the first call. */
719 if (BITS_BIG_ENDIAN != BYTES_BIG_ENDIAN)
722 start = BITS_PER_UNIT - start - size;
725 gcc_assert (REG_P (op));
726 start = BITS_PER_WORD - start - size;
730 gcc_assert (start < (MEM_P (op) ? BITS_PER_UNIT : BITS_PER_WORD));
731 store_bit_field (op, size, start, GET_MODE (x), y);
735 switch (GET_RTX_CLASS (GET_CODE (y)))
738 ot = code_to_optab[GET_CODE (y)];
742 target = expand_unop (GET_MODE (y), ot, XEXP (y, 0), x, 0);
743 if (target != NULL_RTX)
746 emit_move_insn (x, target);
755 ot = code_to_optab[GET_CODE (y)];
759 target = expand_binop (GET_MODE (y), ot,
760 XEXP (y, 0), XEXP (y, 1),
762 if (target != NULL_RTX)
765 emit_move_insn (x, target);
782 inner = XEXP (outer, 0);
783 outmode = GET_MODE (outer);
784 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
785 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y);
788 /* Return sequence of instructions generated by if conversion. This
789 function calls end_sequence() to end the current stream, ensures
790 that are instructions are unshared, recognizable non-jump insns.
791 On failure, this function returns a NULL_RTX. */
794 end_ifcvt_sequence (struct noce_if_info *if_info)
797 rtx seq = get_insns ();
799 set_used_flags (if_info->x);
800 set_used_flags (if_info->cond);
801 unshare_all_rtl_in_chain (seq);
804 /* Make sure that all of the instructions emitted are recognizable,
805 and that we haven't introduced a new jump instruction.
806 As an exercise for the reader, build a general mechanism that
807 allows proper placement of required clobbers. */
808 for (insn = seq; insn; insn = NEXT_INSN (insn))
810 || recog_memoized (insn) == -1)
816 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
817 "if (a == b) x = a; else x = b" into "x = b". */
820 noce_try_move (struct noce_if_info *if_info)
822 rtx cond = if_info->cond;
823 enum rtx_code code = GET_CODE (cond);
826 if (code != NE && code != EQ)
829 /* This optimization isn't valid if either A or B could be a NaN
831 if (HONOR_NANS (GET_MODE (if_info->x))
832 || HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
835 /* Check whether the operands of the comparison are A and in
837 if ((rtx_equal_p (if_info->a, XEXP (cond, 0))
838 && rtx_equal_p (if_info->b, XEXP (cond, 1)))
839 || (rtx_equal_p (if_info->a, XEXP (cond, 1))
840 && rtx_equal_p (if_info->b, XEXP (cond, 0))))
842 y = (code == EQ) ? if_info->a : if_info->b;
844 /* Avoid generating the move if the source is the destination. */
845 if (! rtx_equal_p (if_info->x, y))
848 noce_emit_move_insn (if_info->x, y);
849 seq = end_ifcvt_sequence (if_info);
853 emit_insn_before_setloc (seq, if_info->jump,
854 INSN_LOCATOR (if_info->insn_a));
861 /* Convert "if (test) x = 1; else x = 0".
863 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
864 tried in noce_try_store_flag_constants after noce_try_cmove has had
865 a go at the conversion. */
868 noce_try_store_flag (struct noce_if_info *if_info)
873 if (GET_CODE (if_info->b) == CONST_INT
874 && INTVAL (if_info->b) == STORE_FLAG_VALUE
875 && if_info->a == const0_rtx)
877 else if (if_info->b == const0_rtx
878 && GET_CODE (if_info->a) == CONST_INT
879 && INTVAL (if_info->a) == STORE_FLAG_VALUE
880 && (reversed_comparison_code (if_info->cond, if_info->jump)
888 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
891 if (target != if_info->x)
892 noce_emit_move_insn (if_info->x, target);
894 seq = end_ifcvt_sequence (if_info);
898 emit_insn_before_setloc (seq, if_info->jump,
899 INSN_LOCATOR (if_info->insn_a));
909 /* Convert "if (test) x = a; else x = b", for A and B constant. */
912 noce_try_store_flag_constants (struct noce_if_info *if_info)
916 HOST_WIDE_INT itrue, ifalse, diff, tmp;
917 int normalize, can_reverse;
918 enum machine_mode mode;
921 && GET_CODE (if_info->a) == CONST_INT
922 && GET_CODE (if_info->b) == CONST_INT)
924 mode = GET_MODE (if_info->x);
925 ifalse = INTVAL (if_info->a);
926 itrue = INTVAL (if_info->b);
928 /* Make sure we can represent the difference between the two values. */
929 if ((itrue - ifalse > 0)
930 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
933 diff = trunc_int_for_mode (itrue - ifalse, mode);
935 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
939 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
941 else if (ifalse == 0 && exact_log2 (itrue) >= 0
942 && (STORE_FLAG_VALUE == 1
943 || BRANCH_COST >= 2))
945 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
946 && (STORE_FLAG_VALUE == 1 || BRANCH_COST >= 2))
947 normalize = 1, reversep = 1;
949 && (STORE_FLAG_VALUE == -1
950 || BRANCH_COST >= 2))
952 else if (ifalse == -1 && can_reverse
953 && (STORE_FLAG_VALUE == -1 || BRANCH_COST >= 2))
954 normalize = -1, reversep = 1;
955 else if ((BRANCH_COST >= 2 && STORE_FLAG_VALUE == -1)
963 tmp = itrue; itrue = ifalse; ifalse = tmp;
964 diff = trunc_int_for_mode (-diff, mode);
968 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
975 /* if (test) x = 3; else x = 4;
976 => x = 3 + (test == 0); */
977 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
979 target = expand_simple_binop (mode,
980 (diff == STORE_FLAG_VALUE
982 GEN_INT (ifalse), target, if_info->x, 0,
986 /* if (test) x = 8; else x = 0;
987 => x = (test != 0) << 3; */
988 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
990 target = expand_simple_binop (mode, ASHIFT,
991 target, GEN_INT (tmp), if_info->x, 0,
995 /* if (test) x = -1; else x = b;
996 => x = -(test != 0) | b; */
997 else if (itrue == -1)
999 target = expand_simple_binop (mode, IOR,
1000 target, GEN_INT (ifalse), if_info->x, 0,
1004 /* if (test) x = a; else x = b;
1005 => x = (-(test != 0) & (b - a)) + a; */
1008 target = expand_simple_binop (mode, AND,
1009 target, GEN_INT (diff), if_info->x, 0,
1012 target = expand_simple_binop (mode, PLUS,
1013 target, GEN_INT (ifalse),
1014 if_info->x, 0, OPTAB_WIDEN);
1023 if (target != if_info->x)
1024 noce_emit_move_insn (if_info->x, target);
1026 seq = end_ifcvt_sequence (if_info);
1030 emit_insn_before_setloc (seq, if_info->jump,
1031 INSN_LOCATOR (if_info->insn_a));
1038 /* Convert "if (test) foo++" into "foo += (test != 0)", and
1039 similarly for "foo--". */
1042 noce_try_addcc (struct noce_if_info *if_info)
1045 int subtract, normalize;
1047 if (! no_new_pseudos
1048 && GET_CODE (if_info->a) == PLUS
1049 && rtx_equal_p (XEXP (if_info->a, 0), if_info->b)
1050 && (reversed_comparison_code (if_info->cond, if_info->jump)
1053 rtx cond = if_info->cond;
1054 enum rtx_code code = reversed_comparison_code (cond, if_info->jump);
1056 /* First try to use addcc pattern. */
1057 if (general_operand (XEXP (cond, 0), VOIDmode)
1058 && general_operand (XEXP (cond, 1), VOIDmode))
1061 target = emit_conditional_add (if_info->x, code,
1066 XEXP (if_info->a, 1),
1067 GET_MODE (if_info->x),
1068 (code == LTU || code == GEU
1069 || code == LEU || code == GTU));
1072 if (target != if_info->x)
1073 noce_emit_move_insn (if_info->x, target);
1075 seq = end_ifcvt_sequence (if_info);
1079 emit_insn_before_setloc (seq, if_info->jump,
1080 INSN_LOCATOR (if_info->insn_a));
1086 /* If that fails, construct conditional increment or decrement using
1088 if (BRANCH_COST >= 2
1089 && (XEXP (if_info->a, 1) == const1_rtx
1090 || XEXP (if_info->a, 1) == constm1_rtx))
1093 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1094 subtract = 0, normalize = 0;
1095 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
1096 subtract = 1, normalize = 0;
1098 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
1101 target = noce_emit_store_flag (if_info,
1102 gen_reg_rtx (GET_MODE (if_info->x)),
1106 target = expand_simple_binop (GET_MODE (if_info->x),
1107 subtract ? MINUS : PLUS,
1108 if_info->b, target, if_info->x,
1112 if (target != if_info->x)
1113 noce_emit_move_insn (if_info->x, target);
1115 seq = end_ifcvt_sequence (if_info);
1119 emit_insn_before_setloc (seq, if_info->jump,
1120 INSN_LOCATOR (if_info->insn_a));
1130 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1133 noce_try_store_flag_mask (struct noce_if_info *if_info)
1139 if (! no_new_pseudos
1140 && (BRANCH_COST >= 2
1141 || STORE_FLAG_VALUE == -1)
1142 && ((if_info->a == const0_rtx
1143 && rtx_equal_p (if_info->b, if_info->x))
1144 || ((reversep = (reversed_comparison_code (if_info->cond,
1147 && if_info->b == const0_rtx
1148 && rtx_equal_p (if_info->a, if_info->x))))
1151 target = noce_emit_store_flag (if_info,
1152 gen_reg_rtx (GET_MODE (if_info->x)),
1155 target = expand_simple_binop (GET_MODE (if_info->x), AND,
1157 target, if_info->x, 0,
1162 if (target != if_info->x)
1163 noce_emit_move_insn (if_info->x, target);
1165 seq = end_ifcvt_sequence (if_info);
1169 emit_insn_before_setloc (seq, if_info->jump,
1170 INSN_LOCATOR (if_info->insn_a));
1180 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1183 noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code,
1184 rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue)
1186 /* If earliest == jump, try to build the cmove insn directly.
1187 This is helpful when combine has created some complex condition
1188 (like for alpha's cmovlbs) that we can't hope to regenerate
1189 through the normal interface. */
1191 if (if_info->cond_earliest == if_info->jump)
1195 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
1196 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
1197 tmp = gen_rtx_SET (VOIDmode, x, tmp);
1200 tmp = emit_insn (tmp);
1202 if (recog_memoized (tmp) >= 0)
1214 /* Don't even try if the comparison operands are weird. */
1215 if (! general_operand (cmp_a, GET_MODE (cmp_a))
1216 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
1219 #if HAVE_conditional_move
1220 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
1221 vtrue, vfalse, GET_MODE (x),
1222 (code == LTU || code == GEU
1223 || code == LEU || code == GTU));
1225 /* We'll never get here, as noce_process_if_block doesn't call the
1226 functions involved. Ifdef code, however, should be discouraged
1227 because it leads to typos in the code not selected. However,
1228 emit_conditional_move won't exist either. */
1233 /* Try only simple constants and registers here. More complex cases
1234 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1235 has had a go at it. */
1238 noce_try_cmove (struct noce_if_info *if_info)
1243 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
1244 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
1248 code = GET_CODE (if_info->cond);
1249 target = noce_emit_cmove (if_info, if_info->x, code,
1250 XEXP (if_info->cond, 0),
1251 XEXP (if_info->cond, 1),
1252 if_info->a, if_info->b);
1256 if (target != if_info->x)
1257 noce_emit_move_insn (if_info->x, target);
1259 seq = end_ifcvt_sequence (if_info);
1263 emit_insn_before_setloc (seq, if_info->jump,
1264 INSN_LOCATOR (if_info->insn_a));
1277 /* Try more complex cases involving conditional_move. */
1280 noce_try_cmove_arith (struct noce_if_info *if_info)
1292 /* A conditional move from two memory sources is equivalent to a
1293 conditional on their addresses followed by a load. Don't do this
1294 early because it'll screw alias analysis. Note that we've
1295 already checked for no side effects. */
1296 if (! no_new_pseudos && cse_not_expected
1297 && MEM_P (a) && MEM_P (b)
1298 && BRANCH_COST >= 5)
1302 x = gen_reg_rtx (Pmode);
1306 /* ??? We could handle this if we knew that a load from A or B could
1307 not fault. This is also true if we've already loaded
1308 from the address along the path from ENTRY. */
1309 else if (may_trap_p (a) || may_trap_p (b))
1312 /* if (test) x = a + b; else x = c - d;
1319 code = GET_CODE (if_info->cond);
1320 insn_a = if_info->insn_a;
1321 insn_b = if_info->insn_b;
1323 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1324 if insn_rtx_cost can't be estimated. */
1327 insn_cost = insn_rtx_cost (PATTERN (insn_a));
1328 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (BRANCH_COST))
1336 insn_cost += insn_rtx_cost (PATTERN (insn_b));
1337 if (insn_cost == 0 || insn_cost > COSTS_N_INSNS (BRANCH_COST))
1341 /* Possibly rearrange operands to make things come out more natural. */
1342 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1345 if (rtx_equal_p (b, x))
1347 else if (general_operand (b, GET_MODE (b)))
1352 code = reversed_comparison_code (if_info->cond, if_info->jump);
1353 tmp = a, a = b, b = tmp;
1354 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1363 /* If either operand is complex, load it into a register first.
1364 The best way to do this is to copy the original insn. In this
1365 way we preserve any clobbers etc that the insn may have had.
1366 This is of course not possible in the IS_MEM case. */
1367 if (! general_operand (a, GET_MODE (a)))
1372 goto end_seq_and_fail;
1376 tmp = gen_reg_rtx (GET_MODE (a));
1377 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1380 goto end_seq_and_fail;
1383 a = gen_reg_rtx (GET_MODE (a));
1384 tmp = copy_rtx (insn_a);
1385 set = single_set (tmp);
1387 tmp = emit_insn (PATTERN (tmp));
1389 if (recog_memoized (tmp) < 0)
1390 goto end_seq_and_fail;
1392 if (! general_operand (b, GET_MODE (b)))
1397 goto end_seq_and_fail;
1401 tmp = gen_reg_rtx (GET_MODE (b));
1402 tmp = gen_rtx_SET (VOIDmode, tmp, b);
1405 goto end_seq_and_fail;
1408 b = gen_reg_rtx (GET_MODE (b));
1409 tmp = copy_rtx (insn_b);
1410 set = single_set (tmp);
1412 tmp = PATTERN (tmp);
1415 /* If insn to set up A clobbers any registers B depends on, try to
1416 swap insn that sets up A with the one that sets up B. If even
1417 that doesn't help, punt. */
1418 last = get_last_insn ();
1419 if (last && modified_in_p (orig_b, last))
1421 tmp = emit_insn_before (tmp, get_insns ());
1422 if (modified_in_p (orig_a, tmp))
1423 goto end_seq_and_fail;
1426 tmp = emit_insn (tmp);
1428 if (recog_memoized (tmp) < 0)
1429 goto end_seq_and_fail;
1432 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1433 XEXP (if_info->cond, 1), a, b);
1436 goto end_seq_and_fail;
1438 /* If we're handling a memory for above, emit the load now. */
1441 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1443 /* Copy over flags as appropriate. */
1444 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1445 MEM_VOLATILE_P (tmp) = 1;
1446 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1447 MEM_IN_STRUCT_P (tmp) = 1;
1448 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1449 MEM_SCALAR_P (tmp) = 1;
1450 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1451 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1453 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1455 noce_emit_move_insn (if_info->x, tmp);
1457 else if (target != x)
1458 noce_emit_move_insn (x, target);
1460 tmp = end_ifcvt_sequence (if_info);
1464 emit_insn_before_setloc (tmp, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1472 /* For most cases, the simplified condition we found is the best
1473 choice, but this is not the case for the min/max/abs transforms.
1474 For these we wish to know that it is A or B in the condition. */
1477 noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
1480 rtx cond, set, insn;
1483 /* If target is already mentioned in the known condition, return it. */
1484 if (reg_mentioned_p (target, if_info->cond))
1486 *earliest = if_info->cond_earliest;
1487 return if_info->cond;
1490 set = pc_set (if_info->jump);
1491 cond = XEXP (SET_SRC (set), 0);
1493 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1494 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1496 /* If we're looking for a constant, try to make the conditional
1497 have that constant in it. There are two reasons why it may
1498 not have the constant we want:
1500 1. GCC may have needed to put the constant in a register, because
1501 the target can't compare directly against that constant. For
1502 this case, we look for a SET immediately before the comparison
1503 that puts a constant in that register.
1505 2. GCC may have canonicalized the conditional, for example
1506 replacing "if x < 4" with "if x <= 3". We can undo that (or
1507 make equivalent types of changes) to get the constants we need
1508 if they're off by one in the right direction. */
1510 if (GET_CODE (target) == CONST_INT)
1512 enum rtx_code code = GET_CODE (if_info->cond);
1513 rtx op_a = XEXP (if_info->cond, 0);
1514 rtx op_b = XEXP (if_info->cond, 1);
1517 /* First, look to see if we put a constant in a register. */
1518 prev_insn = prev_nonnote_insn (if_info->cond_earliest);
1520 && INSN_P (prev_insn)
1521 && GET_CODE (PATTERN (prev_insn)) == SET)
1523 rtx src = find_reg_equal_equiv_note (prev_insn);
1525 src = SET_SRC (PATTERN (prev_insn));
1526 if (GET_CODE (src) == CONST_INT)
1528 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1530 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1533 if (GET_CODE (op_a) == CONST_INT)
1538 code = swap_condition (code);
1543 /* Now, look to see if we can get the right constant by
1544 adjusting the conditional. */
1545 if (GET_CODE (op_b) == CONST_INT)
1547 HOST_WIDE_INT desired_val = INTVAL (target);
1548 HOST_WIDE_INT actual_val = INTVAL (op_b);
1553 if (actual_val == desired_val + 1)
1556 op_b = GEN_INT (desired_val);
1560 if (actual_val == desired_val - 1)
1563 op_b = GEN_INT (desired_val);
1567 if (actual_val == desired_val - 1)
1570 op_b = GEN_INT (desired_val);
1574 if (actual_val == desired_val + 1)
1577 op_b = GEN_INT (desired_val);
1585 /* If we made any changes, generate a new conditional that is
1586 equivalent to what we started with, but has the right
1588 if (code != GET_CODE (if_info->cond)
1589 || op_a != XEXP (if_info->cond, 0)
1590 || op_b != XEXP (if_info->cond, 1))
1592 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1593 *earliest = if_info->cond_earliest;
1598 cond = canonicalize_condition (if_info->jump, cond, reverse,
1599 earliest, target, false, true);
1600 if (! cond || ! reg_mentioned_p (target, cond))
1603 /* We almost certainly searched back to a different place.
1604 Need to re-verify correct lifetimes. */
1606 /* X may not be mentioned in the range (cond_earliest, jump]. */
1607 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1608 if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
1611 /* A and B may not be modified in the range [cond_earliest, jump). */
1612 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1614 && (modified_in_p (if_info->a, insn)
1615 || modified_in_p (if_info->b, insn)))
1621 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1624 noce_try_minmax (struct noce_if_info *if_info)
1626 rtx cond, earliest, target, seq;
1627 enum rtx_code code, op;
1630 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1634 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1635 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1636 to get the target to tell us... */
1637 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1638 || HONOR_NANS (GET_MODE (if_info->x)))
1641 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1645 /* Verify the condition is of the form we expect, and canonicalize
1646 the comparison code. */
1647 code = GET_CODE (cond);
1648 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1650 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1653 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1655 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1657 code = swap_condition (code);
1662 /* Determine what sort of operation this is. Note that the code is for
1663 a taken branch, so the code->operation mapping appears backwards. */
1696 target = expand_simple_binop (GET_MODE (if_info->x), op,
1697 if_info->a, if_info->b,
1698 if_info->x, unsignedp, OPTAB_WIDEN);
1704 if (target != if_info->x)
1705 noce_emit_move_insn (if_info->x, target);
1707 seq = end_ifcvt_sequence (if_info);
1711 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1712 if_info->cond = cond;
1713 if_info->cond_earliest = earliest;
1718 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1721 noce_try_abs (struct noce_if_info *if_info)
1723 rtx cond, earliest, target, seq, a, b, c;
1726 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1730 /* Recognize A and B as constituting an ABS or NABS. The canonical
1731 form is a branch around the negation, taken when the object is the
1732 first operand of a comparison against 0 that evaluates to true. */
1735 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1737 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1739 c = a; a = b; b = c;
1745 cond = noce_get_alt_condition (if_info, b, &earliest);
1749 /* Verify the condition is of the form we expect. */
1750 if (rtx_equal_p (XEXP (cond, 0), b))
1752 else if (rtx_equal_p (XEXP (cond, 1), b))
1760 /* Verify that C is zero. Search one step backward for a
1761 REG_EQUAL note or a simple source if necessary. */
1764 rtx set, insn = prev_nonnote_insn (earliest);
1766 && (set = single_set (insn))
1767 && rtx_equal_p (SET_DEST (set), c))
1769 rtx note = find_reg_equal_equiv_note (insn);
1779 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1780 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1781 c = get_pool_constant (XEXP (c, 0));
1783 /* Work around funny ideas get_condition has wrt canonicalization.
1784 Note that these rtx constants are known to be CONST_INT, and
1785 therefore imply integer comparisons. */
1786 if (c == constm1_rtx && GET_CODE (cond) == GT)
1788 else if (c == const1_rtx && GET_CODE (cond) == LT)
1790 else if (c != CONST0_RTX (GET_MODE (b)))
1793 /* Determine what sort of operation this is. */
1794 switch (GET_CODE (cond))
1813 target = expand_abs_nojump (GET_MODE (if_info->x), b, if_info->x, 1);
1815 /* ??? It's a quandary whether cmove would be better here, especially
1816 for integers. Perhaps combine will clean things up. */
1817 if (target && negate)
1818 target = expand_simple_unop (GET_MODE (target), NEG, target, if_info->x, 0);
1826 if (target != if_info->x)
1827 noce_emit_move_insn (if_info->x, target);
1829 seq = end_ifcvt_sequence (if_info);
1833 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1834 if_info->cond = cond;
1835 if_info->cond_earliest = earliest;
1840 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1843 noce_try_sign_mask (struct noce_if_info *if_info)
1845 rtx cond, t, m, c, seq;
1846 enum machine_mode mode;
1852 cond = if_info->cond;
1853 code = GET_CODE (cond);
1858 if (if_info->a == const0_rtx)
1860 if ((code == LT && c == const0_rtx)
1861 || (code == LE && c == constm1_rtx))
1864 else if (if_info->b == const0_rtx)
1866 if ((code == GE && c == const0_rtx)
1867 || (code == GT && c == constm1_rtx))
1871 if (! t || side_effects_p (t))
1874 /* We currently don't handle different modes. */
1875 mode = GET_MODE (t);
1876 if (GET_MODE (m) != mode)
1879 /* This is only profitable if T is cheap, or T is unconditionally
1880 executed/evaluated in the original insn sequence. */
1881 if (rtx_cost (t, SET) >= COSTS_N_INSNS (2)
1882 && (!if_info->b_unconditional
1883 || t != if_info->b))
1887 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1888 "(signed) m >> 31" directly. This benefits targets with specialized
1889 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1890 m = emit_store_flag (gen_reg_rtx (mode), LT, m, const0_rtx, mode, 0, -1);
1891 t = m ? expand_binop (mode, and_optab, m, t, NULL_RTX, 0, OPTAB_DIRECT)
1900 noce_emit_move_insn (if_info->x, t);
1902 seq = end_ifcvt_sequence (if_info);
1906 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1911 /* Optimize away "if (x & C) x |= C" and similar bit manipulation
1915 noce_try_bitop (struct noce_if_info *if_info)
1917 rtx cond, x, a, result, seq;
1918 enum machine_mode mode;
1923 cond = if_info->cond;
1924 code = GET_CODE (cond);
1926 /* Check for no else condition. */
1927 if (! rtx_equal_p (x, if_info->b))
1930 /* Check for a suitable condition. */
1931 if (code != NE && code != EQ)
1933 if (XEXP (cond, 1) != const0_rtx)
1935 cond = XEXP (cond, 0);
1937 /* ??? We could also handle AND here. */
1938 if (GET_CODE (cond) == ZERO_EXTRACT)
1940 if (XEXP (cond, 1) != const1_rtx
1941 || GET_CODE (XEXP (cond, 2)) != CONST_INT
1942 || ! rtx_equal_p (x, XEXP (cond, 0)))
1944 bitnum = INTVAL (XEXP (cond, 2));
1945 mode = GET_MODE (x);
1946 if (bitnum >= HOST_BITS_PER_WIDE_INT)
1953 if (GET_CODE (a) == IOR || GET_CODE (a) == XOR)
1955 /* Check for "if (X & C) x = x op C". */
1956 if (! rtx_equal_p (x, XEXP (a, 0))
1957 || GET_CODE (XEXP (a, 1)) != CONST_INT
1958 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
1959 != (unsigned HOST_WIDE_INT) 1 << bitnum)
1962 /* if ((x & C) == 0) x |= C; is transformed to x |= C. */
1963 /* if ((x & C) != 0) x |= C; is transformed to nothing. */
1964 if (GET_CODE (a) == IOR)
1965 result = (code == NE) ? a : NULL_RTX;
1966 else if (code == NE)
1968 /* if ((x & C) == 0) x ^= C; is transformed to x |= C. */
1969 result = gen_int_mode ((HOST_WIDE_INT) 1 << bitnum, mode);
1970 result = simplify_gen_binary (IOR, mode, x, result);
1974 /* if ((x & C) != 0) x ^= C; is transformed to x &= ~C. */
1975 result = gen_int_mode (~((HOST_WIDE_INT) 1 << bitnum), mode);
1976 result = simplify_gen_binary (AND, mode, x, result);
1979 else if (GET_CODE (a) == AND)
1981 /* Check for "if (X & C) x &= ~C". */
1982 if (! rtx_equal_p (x, XEXP (a, 0))
1983 || GET_CODE (XEXP (a, 1)) != CONST_INT
1984 || (INTVAL (XEXP (a, 1)) & GET_MODE_MASK (mode))
1985 != (~((HOST_WIDE_INT) 1 << bitnum) & GET_MODE_MASK (mode)))
1988 /* if ((x & C) == 0) x &= ~C; is transformed to nothing. */
1989 /* if ((x & C) != 0) x &= ~C; is transformed to x &= ~C. */
1990 result = (code == EQ) ? a : NULL_RTX;
1998 noce_emit_move_insn (x, result);
1999 seq = end_ifcvt_sequence (if_info);
2003 emit_insn_before_setloc (seq, if_info->jump,
2004 INSN_LOCATOR (if_info->insn_a));
2010 /* Similar to get_condition, only the resulting condition must be
2011 valid at JUMP, instead of at EARLIEST. */
2014 noce_get_condition (rtx jump, rtx *earliest)
2019 if (! any_condjump_p (jump))
2022 set = pc_set (jump);
2024 /* If this branches to JUMP_LABEL when the condition is false,
2025 reverse the condition. */
2026 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
2027 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
2029 /* If the condition variable is a register and is MODE_INT, accept it. */
2031 cond = XEXP (SET_SRC (set), 0);
2032 tmp = XEXP (cond, 0);
2033 if (REG_P (tmp) && GET_MODE_CLASS (GET_MODE (tmp)) == MODE_INT)
2038 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
2039 GET_MODE (cond), tmp, XEXP (cond, 1));
2043 /* Otherwise, fall back on canonicalize_condition to do the dirty
2044 work of manipulating MODE_CC values and COMPARE rtx codes. */
2045 return canonicalize_condition (jump, cond, reverse, earliest,
2046 NULL_RTX, false, true);
2049 /* Initialize for a simple IF-THEN or IF-THEN-ELSE block. We will not
2050 be using conditional execution. Set some fields of IF_INFO based
2051 on CE_INFO: test_bb, cond, jump, cond_earliest. Return TRUE if
2055 noce_init_if_info (struct ce_if_block *ce_info, struct noce_if_info *if_info)
2057 basic_block test_bb = ce_info->test_bb;
2060 /* If test is comprised of && or || elements, don't handle it unless
2061 it is the special case of && elements without an ELSE block. */
2062 if (ce_info->num_multiple_test_blocks)
2064 if (ce_info->else_bb || !ce_info->and_and_p)
2067 ce_info->test_bb = test_bb = ce_info->last_test_bb;
2068 ce_info->num_multiple_test_blocks = 0;
2069 ce_info->num_and_and_blocks = 0;
2070 ce_info->num_or_or_blocks = 0;
2073 /* If this is not a standard conditional jump, we can't parse it. */
2074 jump = BB_END (test_bb);
2075 cond = noce_get_condition (jump, &if_info->cond_earliest);
2079 /* If the conditional jump is more than just a conditional
2080 jump, then we can not do if-conversion on this block. */
2081 if (! onlyjump_p (jump))
2084 /* We must be comparing objects whose modes imply the size. */
2085 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2088 if_info->test_bb = test_bb;
2089 if_info->cond = cond;
2090 if_info->jump = jump;
2095 /* Return true if OP is ok for if-then-else processing. */
2098 noce_operand_ok (rtx op)
2100 /* We special-case memories, so handle any of them with
2101 no address side effects. */
2103 return ! side_effects_p (XEXP (op, 0));
2105 if (side_effects_p (op))
2108 return ! may_trap_p (op);
2111 /* Return true if a write into MEM may trap or fault. */
2114 noce_mem_write_may_trap_or_fault_p (rtx mem)
2118 if (MEM_READONLY_P (mem))
2121 if (may_trap_or_fault_p (mem))
2124 addr = XEXP (mem, 0);
2126 /* Call target hook to avoid the effects of -fpic etc.... */
2127 addr = targetm.delegitimize_address (addr);
2130 switch (GET_CODE (addr))
2138 addr = XEXP (addr, 0);
2142 addr = XEXP (addr, 1);
2145 if (GET_CODE (XEXP (addr, 1)) == CONST_INT)
2146 addr = XEXP (addr, 0);
2153 if (SYMBOL_REF_DECL (addr)
2154 && decl_readonly_section (SYMBOL_REF_DECL (addr), 0))
2164 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
2165 without using conditional execution. Return TRUE if we were
2166 successful at converting the block. */
2169 noce_process_if_block (struct ce_if_block * ce_info)
2171 basic_block test_bb = ce_info->test_bb; /* test block */
2172 basic_block then_bb = ce_info->then_bb; /* THEN */
2173 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2174 struct noce_if_info if_info;
2177 rtx orig_x, x, a, b;
2180 /* We're looking for patterns of the form
2182 (1) if (...) x = a; else x = b;
2183 (2) x = b; if (...) x = a;
2184 (3) if (...) x = a; // as if with an initial x = x.
2186 The later patterns require jumps to be more expensive.
2188 ??? For future expansion, look for multiple X in such patterns. */
2190 if (!noce_init_if_info (ce_info, &if_info))
2193 cond = if_info.cond;
2194 jump = if_info.jump;
2196 /* Look for one of the potential sets. */
2197 insn_a = first_active_insn (then_bb);
2199 || insn_a != last_active_insn (then_bb, FALSE)
2200 || (set_a = single_set (insn_a)) == NULL_RTX)
2203 x = SET_DEST (set_a);
2204 a = SET_SRC (set_a);
2206 /* Look for the other potential set. Make sure we've got equivalent
2208 /* ??? This is overconservative. Storing to two different mems is
2209 as easy as conditionally computing the address. Storing to a
2210 single mem merely requires a scratch memory to use as one of the
2211 destination addresses; often the memory immediately below the
2212 stack pointer is available for this. */
2216 insn_b = first_active_insn (else_bb);
2218 || insn_b != last_active_insn (else_bb, FALSE)
2219 || (set_b = single_set (insn_b)) == NULL_RTX
2220 || ! rtx_equal_p (x, SET_DEST (set_b)))
2225 insn_b = prev_nonnote_insn (if_info.cond_earliest);
2226 /* We're going to be moving the evaluation of B down from above
2227 COND_EARLIEST to JUMP. Make sure the relevant data is still
2230 || !NONJUMP_INSN_P (insn_b)
2231 || (set_b = single_set (insn_b)) == NULL_RTX
2232 || ! rtx_equal_p (x, SET_DEST (set_b))
2233 || reg_overlap_mentioned_p (x, SET_SRC (set_b))
2234 || modified_between_p (SET_SRC (set_b),
2235 PREV_INSN (if_info.cond_earliest), jump)
2236 /* Likewise with X. In particular this can happen when
2237 noce_get_condition looks farther back in the instruction
2238 stream than one might expect. */
2239 || reg_overlap_mentioned_p (x, cond)
2240 || reg_overlap_mentioned_p (x, a)
2241 || modified_between_p (x, PREV_INSN (if_info.cond_earliest), jump))
2242 insn_b = set_b = NULL_RTX;
2245 /* If x has side effects then only the if-then-else form is safe to
2246 convert. But even in that case we would need to restore any notes
2247 (such as REG_INC) at then end. That can be tricky if
2248 noce_emit_move_insn expands to more than one insn, so disable the
2249 optimization entirely for now if there are side effects. */
2250 if (side_effects_p (x))
2253 b = (set_b ? SET_SRC (set_b) : x);
2255 /* Only operate on register destinations, and even then avoid extending
2256 the lifetime of hard registers on small register class machines. */
2259 || (SMALL_REGISTER_CLASSES
2260 && REGNO (x) < FIRST_PSEUDO_REGISTER))
2262 if (no_new_pseudos || GET_MODE (x) == BLKmode)
2265 if (GET_MODE (x) == ZERO_EXTRACT
2266 && (GET_CODE (XEXP (x, 1)) != CONST_INT
2267 || GET_CODE (XEXP (x, 2)) != CONST_INT))
2270 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
2271 ? XEXP (x, 0) : x));
2274 /* Don't operate on sources that may trap or are volatile. */
2275 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
2278 /* Set up the info block for our subroutines. */
2279 if_info.insn_a = insn_a;
2280 if_info.insn_b = insn_b;
2284 if_info.b_unconditional = else_bb == 0;
2286 /* Try optimizations in some approximation of a useful order. */
2287 /* ??? Should first look to see if X is live incoming at all. If it
2288 isn't, we don't need anything but an unconditional set. */
2290 /* Look and see if A and B are really the same. Avoid creating silly
2291 cmove constructs that no one will fix up later. */
2292 if (rtx_equal_p (a, b))
2294 /* If we have an INSN_B, we don't have to create any new rtl. Just
2295 move the instruction that we already have. If we don't have an
2296 INSN_B, that means that A == X, and we've got a noop move. In
2297 that case don't do anything and let the code below delete INSN_A. */
2298 if (insn_b && else_bb)
2302 if (else_bb && insn_b == BB_END (else_bb))
2303 BB_END (else_bb) = PREV_INSN (insn_b);
2304 reorder_insns (insn_b, insn_b, PREV_INSN (jump));
2306 /* If there was a REG_EQUAL note, delete it since it may have been
2307 true due to this insn being after a jump. */
2308 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
2309 remove_note (insn_b, note);
2313 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2314 x must be executed twice. */
2315 else if (insn_b && side_effects_p (orig_x))
2322 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2323 for optimizations if writing to x may trap or fault, i.e. it's a memory
2324 other than a static var or a stack slot, is misaligned on strict
2325 aligned machines or is read-only.
2326 If x is a read-only memory, then the program is valid only if we
2327 avoid the store into it. If there are stores on both the THEN and
2328 ELSE arms, then we can go ahead with the conversion; either the
2329 program is broken, or the condition is always false such that the
2330 other memory is selected. */
2331 if (!set_b && MEM_P (orig_x) && noce_mem_write_may_trap_or_fault_p (orig_x))
2334 if (noce_try_move (&if_info))
2336 if (noce_try_store_flag (&if_info))
2338 if (noce_try_bitop (&if_info))
2340 if (noce_try_minmax (&if_info))
2342 if (noce_try_abs (&if_info))
2344 if (HAVE_conditional_move
2345 && noce_try_cmove (&if_info))
2347 if (! HAVE_conditional_execution)
2349 if (noce_try_store_flag_constants (&if_info))
2351 if (noce_try_addcc (&if_info))
2353 if (noce_try_store_flag_mask (&if_info))
2355 if (HAVE_conditional_move
2356 && noce_try_cmove_arith (&if_info))
2358 if (noce_try_sign_mask (&if_info))
2365 /* The original sets may now be killed. */
2366 delete_insn (insn_a);
2368 /* Several special cases here: First, we may have reused insn_b above,
2369 in which case insn_b is now NULL. Second, we want to delete insn_b
2370 if it came from the ELSE block, because follows the now correct
2371 write that appears in the TEST block. However, if we got insn_b from
2372 the TEST block, it may in fact be loading data needed for the comparison.
2373 We'll let life_analysis remove the insn if it's really dead. */
2374 if (insn_b && else_bb)
2375 delete_insn (insn_b);
2377 /* The new insns will have been inserted immediately before the jump. We
2378 should be able to remove the jump with impunity, but the condition itself
2379 may have been modified by gcse to be shared across basic blocks. */
2382 /* If we used a temporary, fix it up now. */
2386 noce_emit_move_insn (orig_x, x);
2387 insn_b = get_insns ();
2388 set_used_flags (orig_x);
2389 unshare_all_rtl_in_chain (insn_b);
2392 emit_insn_after_setloc (insn_b, BB_END (test_bb), INSN_LOCATOR (insn_a));
2395 /* Merge the blocks! */
2396 merge_if_block (ce_info);
2401 /* Check whether a block is suitable for conditional move conversion.
2402 Every insn must be a simple set of a register to a constant or a
2403 register. For each assignment, store the value in the array VALS,
2404 indexed by register number. COND is the condition we will
2408 check_cond_move_block (basic_block bb, rtx *vals, rtx cond)
2412 FOR_BB_INSNS (bb, insn)
2416 if (!INSN_P (insn) || JUMP_P (insn))
2418 set = single_set (insn);
2422 dest = SET_DEST (set);
2423 src = SET_SRC (set);
2425 || (SMALL_REGISTER_CLASSES && HARD_REGISTER_P (dest)))
2428 if (!CONSTANT_P (src) && !register_operand (src, VOIDmode))
2431 if (side_effects_p (src) || side_effects_p (dest))
2434 if (may_trap_p (src) || may_trap_p (dest))
2437 /* Don't try to handle this if the source register was
2438 modified earlier in the block. */
2440 && vals[REGNO (src)] != NULL)
2441 || (GET_CODE (src) == SUBREG && REG_P (SUBREG_REG (src))
2442 && vals[REGNO (SUBREG_REG (src))] != NULL))
2445 /* Don't try to handle this if the destination register was
2446 modified earlier in the block. */
2447 if (vals[REGNO (dest)] != NULL)
2450 /* Don't try to handle this if the condition uses the
2451 destination register. */
2452 if (reg_overlap_mentioned_p (dest, cond))
2455 vals[REGNO (dest)] = src;
2457 /* Don't try to handle this if the source register is modified
2458 later in the block. */
2459 if (!CONSTANT_P (src)
2460 && modified_between_p (src, insn, NEXT_INSN (BB_END (bb))))
2467 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
2468 using only conditional moves. Return TRUE if we were successful at
2469 converting the block. */
2472 cond_move_process_if_block (struct ce_if_block *ce_info)
2474 basic_block then_bb = ce_info->then_bb;
2475 basic_block else_bb = ce_info->else_bb;
2476 struct noce_if_info if_info;
2477 rtx jump, cond, insn, seq, cond_arg0, cond_arg1, loc_insn;
2478 int max_reg, size, c, i;
2483 if (!HAVE_conditional_move || no_new_pseudos)
2486 memset (&if_info, 0, sizeof if_info);
2488 if (!noce_init_if_info (ce_info, &if_info))
2491 cond = if_info.cond;
2492 jump = if_info.jump;
2494 /* Build a mapping for each block to the value used for each
2496 max_reg = max_reg_num ();
2497 size = (max_reg + 1) * sizeof (rtx);
2498 then_vals = (rtx *) alloca (size);
2499 else_vals = (rtx *) alloca (size);
2500 memset (then_vals, 0, size);
2501 memset (else_vals, 0, size);
2503 /* Make sure the blocks are suitable. */
2504 if (!check_cond_move_block (then_bb, then_vals, cond)
2505 || (else_bb && !check_cond_move_block (else_bb, else_vals, cond)))
2508 /* Make sure the blocks can be used together. If the same register
2509 is set in both blocks, and is not set to a constant in both
2510 cases, then both blocks must set it to the same register. We
2511 have already verified that if it is set to a register, that the
2512 source register does not change after the assignment. Also count
2513 the number of registers set in only one of the blocks. */
2515 for (i = 0; i <= max_reg; ++i)
2517 if (!then_vals[i] && !else_vals[i])
2520 if (!then_vals[i] || !else_vals[i])
2524 if (!CONSTANT_P (then_vals[i])
2525 && !CONSTANT_P (else_vals[i])
2526 && !rtx_equal_p (then_vals[i], else_vals[i]))
2531 /* Make sure it is reasonable to convert this block. What matters
2532 is the number of assignments currently made in only one of the
2533 branches, since if we convert we are going to always execute
2535 if (c > MAX_CONDITIONAL_EXECUTE)
2538 /* Emit the conditional moves. First do the then block, then do
2539 anything left in the else blocks. */
2541 code = GET_CODE (cond);
2542 cond_arg0 = XEXP (cond, 0);
2543 cond_arg1 = XEXP (cond, 1);
2547 FOR_BB_INSNS (then_bb, insn)
2549 rtx set, target, dest, t, e;
2552 if (!INSN_P (insn) || JUMP_P (insn))
2554 set = single_set (insn);
2555 gcc_assert (set && REG_P (SET_DEST (set)));
2557 dest = SET_DEST (set);
2558 regno = REGNO (dest);
2559 t = then_vals[regno];
2560 e = else_vals[regno];
2564 target = noce_emit_cmove (&if_info, dest, code, cond_arg0, cond_arg1,
2573 noce_emit_move_insn (dest, target);
2578 FOR_BB_INSNS (else_bb, insn)
2580 rtx set, target, dest;
2583 if (!INSN_P (insn) || JUMP_P (insn))
2585 set = single_set (insn);
2586 gcc_assert (set && REG_P (SET_DEST (set)));
2588 dest = SET_DEST (set);
2589 regno = REGNO (dest);
2591 /* If this register was set in the then block, we already
2592 handled this case above. */
2593 if (then_vals[regno])
2595 gcc_assert (else_vals[regno]);
2597 target = noce_emit_cmove (&if_info, dest, code, cond_arg0, cond_arg1,
2598 dest, else_vals[regno]);
2606 noce_emit_move_insn (dest, target);
2610 seq = end_ifcvt_sequence (&if_info);
2614 loc_insn = first_active_insn (then_bb);
2617 loc_insn = first_active_insn (else_bb);
2618 gcc_assert (loc_insn);
2620 emit_insn_before_setloc (seq, jump, INSN_LOCATOR (loc_insn));
2622 FOR_BB_INSNS (then_bb, insn)
2623 if (INSN_P (insn) && !JUMP_P (insn))
2627 FOR_BB_INSNS (else_bb, insn)
2628 if (INSN_P (insn) && !JUMP_P (insn))
2633 merge_if_block (ce_info);
2638 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2639 straight line code. Return true if successful. */
2642 process_if_block (struct ce_if_block * ce_info)
2644 if (! reload_completed
2645 && noce_process_if_block (ce_info))
2648 if (HAVE_conditional_move
2649 && cond_move_process_if_block (ce_info))
2652 if (HAVE_conditional_execution && reload_completed)
2654 /* If we have && and || tests, try to first handle combining the && and
2655 || tests into the conditional code, and if that fails, go back and
2656 handle it without the && and ||, which at present handles the && case
2657 if there was no ELSE block. */
2658 if (cond_exec_process_if_block (ce_info, TRUE))
2661 if (ce_info->num_multiple_test_blocks)
2665 if (cond_exec_process_if_block (ce_info, FALSE))
2673 /* Merge the blocks and mark for local life update. */
2676 merge_if_block (struct ce_if_block * ce_info)
2678 basic_block test_bb = ce_info->test_bb; /* last test block */
2679 basic_block then_bb = ce_info->then_bb; /* THEN */
2680 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2681 basic_block join_bb = ce_info->join_bb; /* join block */
2682 basic_block combo_bb;
2684 /* All block merging is done into the lower block numbers. */
2688 /* Merge any basic blocks to handle && and || subtests. Each of
2689 the blocks are on the fallthru path from the predecessor block. */
2690 if (ce_info->num_multiple_test_blocks > 0)
2692 basic_block bb = test_bb;
2693 basic_block last_test_bb = ce_info->last_test_bb;
2694 basic_block fallthru = block_fallthru (bb);
2699 fallthru = block_fallthru (bb);
2700 merge_blocks (combo_bb, bb);
2703 while (bb != last_test_bb);
2706 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2707 label, but it might if there were || tests. That label's count should be
2708 zero, and it normally should be removed. */
2712 if (combo_bb->il.rtl->global_live_at_end)
2713 COPY_REG_SET (combo_bb->il.rtl->global_live_at_end,
2714 then_bb->il.rtl->global_live_at_end);
2715 merge_blocks (combo_bb, then_bb);
2719 /* The ELSE block, if it existed, had a label. That label count
2720 will almost always be zero, but odd things can happen when labels
2721 get their addresses taken. */
2724 merge_blocks (combo_bb, else_bb);
2728 /* If there was no join block reported, that means it was not adjacent
2729 to the others, and so we cannot merge them. */
2733 rtx last = BB_END (combo_bb);
2735 /* The outgoing edge for the current COMBO block should already
2736 be correct. Verify this. */
2737 if (EDGE_COUNT (combo_bb->succs) == 0)
2738 gcc_assert (find_reg_note (last, REG_NORETURN, NULL)
2739 || (NONJUMP_INSN_P (last)
2740 && GET_CODE (PATTERN (last)) == TRAP_IF
2741 && (TRAP_CONDITION (PATTERN (last))
2742 == const_true_rtx)));
2745 /* There should still be something at the end of the THEN or ELSE
2746 blocks taking us to our final destination. */
2747 gcc_assert (JUMP_P (last)
2748 || (EDGE_SUCC (combo_bb, 0)->dest == EXIT_BLOCK_PTR
2750 && SIBLING_CALL_P (last))
2751 || ((EDGE_SUCC (combo_bb, 0)->flags & EDGE_EH)
2752 && can_throw_internal (last)));
2755 /* The JOIN block may have had quite a number of other predecessors too.
2756 Since we've already merged the TEST, THEN and ELSE blocks, we should
2757 have only one remaining edge from our if-then-else diamond. If there
2758 is more than one remaining edge, it must come from elsewhere. There
2759 may be zero incoming edges if the THEN block didn't actually join
2760 back up (as with a call to a non-return function). */
2761 else if (EDGE_COUNT (join_bb->preds) < 2
2762 && join_bb != EXIT_BLOCK_PTR)
2764 /* We can merge the JOIN. */
2765 if (combo_bb->il.rtl->global_live_at_end)
2766 COPY_REG_SET (combo_bb->il.rtl->global_live_at_end,
2767 join_bb->il.rtl->global_live_at_end);
2769 merge_blocks (combo_bb, join_bb);
2774 /* We cannot merge the JOIN. */
2776 /* The outgoing edge for the current COMBO block should already
2777 be correct. Verify this. */
2778 gcc_assert (single_succ_p (combo_bb)
2779 && single_succ (combo_bb) == join_bb);
2781 /* Remove the jump and cruft from the end of the COMBO block. */
2782 if (join_bb != EXIT_BLOCK_PTR)
2783 tidy_fallthru_edge (single_succ_edge (combo_bb));
2786 num_updated_if_blocks++;
2789 /* Find a block ending in a simple IF condition and try to transform it
2790 in some way. When converting a multi-block condition, put the new code
2791 in the first such block and delete the rest. Return a pointer to this
2792 first block if some transformation was done. Return NULL otherwise. */
2795 find_if_header (basic_block test_bb, int pass)
2797 ce_if_block_t ce_info;
2801 /* The kind of block we're looking for has exactly two successors. */
2802 if (EDGE_COUNT (test_bb->succs) != 2)
2805 then_edge = EDGE_SUCC (test_bb, 0);
2806 else_edge = EDGE_SUCC (test_bb, 1);
2808 /* Neither edge should be abnormal. */
2809 if ((then_edge->flags & EDGE_COMPLEX)
2810 || (else_edge->flags & EDGE_COMPLEX))
2813 /* Nor exit the loop. */
2814 if ((then_edge->flags & EDGE_LOOP_EXIT)
2815 || (else_edge->flags & EDGE_LOOP_EXIT))
2818 /* The THEN edge is canonically the one that falls through. */
2819 if (then_edge->flags & EDGE_FALLTHRU)
2821 else if (else_edge->flags & EDGE_FALLTHRU)
2824 else_edge = then_edge;
2828 /* Otherwise this must be a multiway branch of some sort. */
2831 memset (&ce_info, '\0', sizeof (ce_info));
2832 ce_info.test_bb = test_bb;
2833 ce_info.then_bb = then_edge->dest;
2834 ce_info.else_bb = else_edge->dest;
2835 ce_info.pass = pass;
2837 #ifdef IFCVT_INIT_EXTRA_FIELDS
2838 IFCVT_INIT_EXTRA_FIELDS (&ce_info);
2841 if (find_if_block (&ce_info))
2844 if (HAVE_trap && HAVE_conditional_trap
2845 && find_cond_trap (test_bb, then_edge, else_edge))
2848 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY
2849 && (! HAVE_conditional_execution || reload_completed))
2851 if (find_if_case_1 (test_bb, then_edge, else_edge))
2853 if (find_if_case_2 (test_bb, then_edge, else_edge))
2861 fprintf (dump_file, "Conversion succeeded on pass %d.\n", pass);
2862 return ce_info.test_bb;
2865 /* Return true if a block has two edges, one of which falls through to the next
2866 block, and the other jumps to a specific block, so that we can tell if the
2867 block is part of an && test or an || test. Returns either -1 or the number
2868 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2871 block_jumps_and_fallthru_p (basic_block cur_bb, basic_block target_bb)
2874 int fallthru_p = FALSE;
2881 if (!cur_bb || !target_bb)
2884 /* If no edges, obviously it doesn't jump or fallthru. */
2885 if (EDGE_COUNT (cur_bb->succs) == 0)
2888 FOR_EACH_EDGE (cur_edge, ei, cur_bb->succs)
2890 if (cur_edge->flags & EDGE_COMPLEX)
2891 /* Anything complex isn't what we want. */
2894 else if (cur_edge->flags & EDGE_FALLTHRU)
2897 else if (cur_edge->dest == target_bb)
2904 if ((jump_p & fallthru_p) == 0)
2907 /* Don't allow calls in the block, since this is used to group && and ||
2908 together for conditional execution support. ??? we should support
2909 conditional execution support across calls for IA-64 some day, but
2910 for now it makes the code simpler. */
2911 end = BB_END (cur_bb);
2912 insn = BB_HEAD (cur_bb);
2914 while (insn != NULL_RTX)
2921 && GET_CODE (PATTERN (insn)) != USE
2922 && GET_CODE (PATTERN (insn)) != CLOBBER)
2928 insn = NEXT_INSN (insn);
2934 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2935 block. If so, we'll try to convert the insns to not require the branch.
2936 Return TRUE if we were successful at converting the block. */
2939 find_if_block (struct ce_if_block * ce_info)
2941 basic_block test_bb = ce_info->test_bb;
2942 basic_block then_bb = ce_info->then_bb;
2943 basic_block else_bb = ce_info->else_bb;
2944 basic_block join_bb = NULL_BLOCK;
2949 ce_info->last_test_bb = test_bb;
2951 /* Discover if any fall through predecessors of the current test basic block
2952 were && tests (which jump to the else block) or || tests (which jump to
2954 if (HAVE_conditional_execution && reload_completed
2955 && single_pred_p (test_bb)
2956 && single_pred_edge (test_bb)->flags == EDGE_FALLTHRU)
2958 basic_block bb = single_pred (test_bb);
2959 basic_block target_bb;
2960 int max_insns = MAX_CONDITIONAL_EXECUTE;
2963 /* Determine if the preceding block is an && or || block. */
2964 if ((n_insns = block_jumps_and_fallthru_p (bb, else_bb)) >= 0)
2966 ce_info->and_and_p = TRUE;
2967 target_bb = else_bb;
2969 else if ((n_insns = block_jumps_and_fallthru_p (bb, then_bb)) >= 0)
2971 ce_info->and_and_p = FALSE;
2972 target_bb = then_bb;
2975 target_bb = NULL_BLOCK;
2977 if (target_bb && n_insns <= max_insns)
2979 int total_insns = 0;
2982 ce_info->last_test_bb = test_bb;
2984 /* Found at least one && or || block, look for more. */
2987 ce_info->test_bb = test_bb = bb;
2988 total_insns += n_insns;
2991 if (!single_pred_p (bb))
2994 bb = single_pred (bb);
2995 n_insns = block_jumps_and_fallthru_p (bb, target_bb);
2997 while (n_insns >= 0 && (total_insns + n_insns) <= max_insns);
2999 ce_info->num_multiple_test_blocks = blocks;
3000 ce_info->num_multiple_test_insns = total_insns;
3002 if (ce_info->and_and_p)
3003 ce_info->num_and_and_blocks = blocks;
3005 ce_info->num_or_or_blocks = blocks;
3009 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
3010 other than any || blocks which jump to the THEN block. */
3011 if ((EDGE_COUNT (then_bb->preds) - ce_info->num_or_or_blocks) != 1)
3014 /* The edges of the THEN and ELSE blocks cannot have complex edges. */
3015 FOR_EACH_EDGE (cur_edge, ei, then_bb->preds)
3017 if (cur_edge->flags & EDGE_COMPLEX)
3021 FOR_EACH_EDGE (cur_edge, ei, else_bb->preds)
3023 if (cur_edge->flags & EDGE_COMPLEX)
3027 /* The THEN block of an IF-THEN combo must have zero or one successors. */
3028 if (EDGE_COUNT (then_bb->succs) > 0
3029 && (!single_succ_p (then_bb)
3030 || (single_succ_edge (then_bb)->flags & EDGE_COMPLEX)
3031 || (flow2_completed && tablejump_p (BB_END (then_bb), NULL, NULL))))
3034 /* If the THEN block has no successors, conditional execution can still
3035 make a conditional call. Don't do this unless the ELSE block has
3036 only one incoming edge -- the CFG manipulation is too ugly otherwise.
3037 Check for the last insn of the THEN block being an indirect jump, which
3038 is listed as not having any successors, but confuses the rest of the CE
3039 code processing. ??? we should fix this in the future. */
3040 if (EDGE_COUNT (then_bb->succs) == 0)
3042 if (single_pred_p (else_bb))
3044 rtx last_insn = BB_END (then_bb);
3047 && NOTE_P (last_insn)
3048 && last_insn != BB_HEAD (then_bb))
3049 last_insn = PREV_INSN (last_insn);
3052 && JUMP_P (last_insn)
3053 && ! simplejump_p (last_insn))
3057 else_bb = NULL_BLOCK;
3063 /* If the THEN block's successor is the other edge out of the TEST block,
3064 then we have an IF-THEN combo without an ELSE. */
3065 else if (single_succ (then_bb) == else_bb)
3068 else_bb = NULL_BLOCK;
3071 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
3072 has exactly one predecessor and one successor, and the outgoing edge
3073 is not complex, then we have an IF-THEN-ELSE combo. */
3074 else if (single_succ_p (else_bb)
3075 && single_succ (then_bb) == single_succ (else_bb)
3076 && single_pred_p (else_bb)
3077 && ! (single_succ_edge (else_bb)->flags & EDGE_COMPLEX)
3078 && ! (flow2_completed && tablejump_p (BB_END (else_bb), NULL, NULL)))
3079 join_bb = single_succ (else_bb);
3081 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
3085 num_possible_if_blocks++;
3090 "\nIF-THEN%s block found, pass %d, start block %d "
3091 "[insn %d], then %d [%d]",
3092 (else_bb) ? "-ELSE" : "",
3095 BB_HEAD (test_bb) ? (int)INSN_UID (BB_HEAD (test_bb)) : -1,
3097 BB_HEAD (then_bb) ? (int)INSN_UID (BB_HEAD (then_bb)) : -1);
3100 fprintf (dump_file, ", else %d [%d]",
3102 BB_HEAD (else_bb) ? (int)INSN_UID (BB_HEAD (else_bb)) : -1);
3104 fprintf (dump_file, ", join %d [%d]",
3106 BB_HEAD (join_bb) ? (int)INSN_UID (BB_HEAD (join_bb)) : -1);
3108 if (ce_info->num_multiple_test_blocks > 0)
3109 fprintf (dump_file, ", %d %s block%s last test %d [%d]",
3110 ce_info->num_multiple_test_blocks,
3111 (ce_info->and_and_p) ? "&&" : "||",
3112 (ce_info->num_multiple_test_blocks == 1) ? "" : "s",
3113 ce_info->last_test_bb->index,
3114 ((BB_HEAD (ce_info->last_test_bb))
3115 ? (int)INSN_UID (BB_HEAD (ce_info->last_test_bb))
3118 fputc ('\n', dump_file);
3121 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
3122 first condition for free, since we've already asserted that there's a
3123 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
3124 we checked the FALLTHRU flag, those are already adjacent to the last IF
3126 /* ??? As an enhancement, move the ELSE block. Have to deal with
3127 BLOCK notes, if by no other means than backing out the merge if they
3128 exist. Sticky enough I don't want to think about it now. */
3130 if (else_bb && (next = next->next_bb) != else_bb)
3132 if ((next = next->next_bb) != join_bb && join_bb != EXIT_BLOCK_PTR)
3140 /* Do the real work. */
3141 ce_info->else_bb = else_bb;
3142 ce_info->join_bb = join_bb;
3144 return process_if_block (ce_info);
3147 /* Convert a branch over a trap, or a branch
3148 to a trap, into a conditional trap. */
3151 find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
3153 basic_block then_bb = then_edge->dest;
3154 basic_block else_bb = else_edge->dest;
3155 basic_block other_bb, trap_bb;
3156 rtx trap, jump, cond, cond_earliest, seq;
3159 /* Locate the block with the trap instruction. */
3160 /* ??? While we look for no successors, we really ought to allow
3161 EH successors. Need to fix merge_if_block for that to work. */
3162 if ((trap = block_has_only_trap (then_bb)) != NULL)
3163 trap_bb = then_bb, other_bb = else_bb;
3164 else if ((trap = block_has_only_trap (else_bb)) != NULL)
3165 trap_bb = else_bb, other_bb = then_bb;
3171 fprintf (dump_file, "\nTRAP-IF block found, start %d, trap %d\n",
3172 test_bb->index, trap_bb->index);
3175 /* If this is not a standard conditional jump, we can't parse it. */
3176 jump = BB_END (test_bb);
3177 cond = noce_get_condition (jump, &cond_earliest);
3181 /* If the conditional jump is more than just a conditional jump, then
3182 we can not do if-conversion on this block. */
3183 if (! onlyjump_p (jump))
3186 /* We must be comparing objects whose modes imply the size. */
3187 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
3190 /* Reverse the comparison code, if necessary. */
3191 code = GET_CODE (cond);
3192 if (then_bb == trap_bb)
3194 code = reversed_comparison_code (cond, jump);
3195 if (code == UNKNOWN)
3199 /* Attempt to generate the conditional trap. */
3200 seq = gen_cond_trap (code, XEXP (cond, 0),
3202 TRAP_CODE (PATTERN (trap)));
3208 /* Emit the new insns before cond_earliest. */
3209 emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
3211 /* Delete the trap block if possible. */
3212 remove_edge (trap_bb == then_bb ? then_edge : else_edge);
3213 if (EDGE_COUNT (trap_bb->preds) == 0)
3214 delete_basic_block (trap_bb);
3216 /* If the non-trap block and the test are now adjacent, merge them.
3217 Otherwise we must insert a direct branch. */
3218 if (test_bb->next_bb == other_bb)
3220 struct ce_if_block new_ce_info;
3222 memset (&new_ce_info, '\0', sizeof (new_ce_info));
3223 new_ce_info.test_bb = test_bb;
3224 new_ce_info.then_bb = NULL;
3225 new_ce_info.else_bb = NULL;
3226 new_ce_info.join_bb = other_bb;
3227 merge_if_block (&new_ce_info);
3233 lab = JUMP_LABEL (jump);
3234 newjump = emit_jump_insn_after (gen_jump (lab), jump);
3235 LABEL_NUSES (lab) += 1;
3236 JUMP_LABEL (newjump) = lab;
3237 emit_barrier_after (newjump);
3245 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
3249 block_has_only_trap (basic_block bb)
3253 /* We're not the exit block. */
3254 if (bb == EXIT_BLOCK_PTR)
3257 /* The block must have no successors. */
3258 if (EDGE_COUNT (bb->succs) > 0)
3261 /* The only instruction in the THEN block must be the trap. */
3262 trap = first_active_insn (bb);
3263 if (! (trap == BB_END (bb)
3264 && GET_CODE (PATTERN (trap)) == TRAP_IF
3265 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
3271 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
3272 transformable, but not necessarily the other. There need be no
3275 Return TRUE if we were successful at converting the block.
3277 Cases we'd like to look at:
3280 if (test) goto over; // x not live
3288 if (! test) goto label;
3291 if (test) goto E; // x not live
3305 (3) // This one's really only interesting for targets that can do
3306 // multiway branching, e.g. IA-64 BBB bundles. For other targets
3307 // it results in multiple branches on a cache line, which often
3308 // does not sit well with predictors.
3310 if (test1) goto E; // predicted not taken
3326 (A) Don't do (2) if the branch is predicted against the block we're
3327 eliminating. Do it anyway if we can eliminate a branch; this requires
3328 that the sole successor of the eliminated block postdominate the other
3331 (B) With CE, on (3) we can steal from both sides of the if, creating
3340 Again, this is most useful if J postdominates.
3342 (C) CE substitutes for helpful life information.
3344 (D) These heuristics need a lot of work. */
3346 /* Tests for case 1 above. */
3349 find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
3351 basic_block then_bb = then_edge->dest;
3352 basic_block else_bb = else_edge->dest, new_bb;
3355 /* If we are partitioning hot/cold basic blocks, we don't want to
3356 mess up unconditional or indirect jumps that cross between hot
3359 Basic block partitioning may result in some jumps that appear to
3360 be optimizable (or blocks that appear to be mergeable), but which really
3361 must be left untouched (they are required to make it safely across
3362 partition boundaries). See the comments at the top of
3363 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3365 if ((BB_END (then_bb)
3366 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3367 || (BB_END (test_bb)
3368 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3369 || (BB_END (else_bb)
3370 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3374 /* THEN has one successor. */
3375 if (!single_succ_p (then_bb))
3378 /* THEN does not fall through, but is not strange either. */
3379 if (single_succ_edge (then_bb)->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
3382 /* THEN has one predecessor. */
3383 if (!single_pred_p (then_bb))
3386 /* THEN must do something. */
3387 if (forwarder_block_p (then_bb))
3390 num_possible_if_blocks++;
3393 "\nIF-CASE-1 found, start %d, then %d\n",
3394 test_bb->index, then_bb->index);
3396 /* THEN is small. */
3397 if (! cheap_bb_rtx_cost_p (then_bb, COSTS_N_INSNS (BRANCH_COST)))
3400 /* Registers set are dead, or are predicable. */
3401 if (! dead_or_predicable (test_bb, then_bb, else_bb,
3402 single_succ (then_bb), 1))
3405 /* Conversion went ok, including moving the insns and fixing up the
3406 jump. Adjust the CFG to match. */
3408 bitmap_ior (test_bb->il.rtl->global_live_at_end,
3409 else_bb->il.rtl->global_live_at_start,
3410 then_bb->il.rtl->global_live_at_end);
3413 /* We can avoid creating a new basic block if then_bb is immediately
3414 followed by else_bb, i.e. deleting then_bb allows test_bb to fall
3417 if (then_bb->next_bb == else_bb
3418 && then_bb->prev_bb == test_bb
3419 && else_bb != EXIT_BLOCK_PTR)
3421 redirect_edge_succ (FALLTHRU_EDGE (test_bb), else_bb);
3425 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb),
3428 then_bb_index = then_bb->index;
3429 delete_basic_block (then_bb);
3431 /* Make rest of code believe that the newly created block is the THEN_BB
3432 block we removed. */
3435 new_bb->index = then_bb_index;
3436 SET_BASIC_BLOCK (then_bb_index, new_bb);
3437 /* Since the fallthru edge was redirected from test_bb to new_bb,
3438 we need to ensure that new_bb is in the same partition as
3439 test bb (you can not fall through across section boundaries). */
3440 BB_COPY_PARTITION (new_bb, test_bb);
3442 /* We've possibly created jump to next insn, cleanup_cfg will solve that
3446 num_updated_if_blocks++;
3451 /* Test for case 2 above. */
3454 find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
3456 basic_block then_bb = then_edge->dest;
3457 basic_block else_bb = else_edge->dest;
3461 /* If we are partitioning hot/cold basic blocks, we don't want to
3462 mess up unconditional or indirect jumps that cross between hot
3465 Basic block partitioning may result in some jumps that appear to
3466 be optimizable (or blocks that appear to be mergeable), but which really
3467 must be left untouched (they are required to make it safely across
3468 partition boundaries). See the comments at the top of
3469 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
3471 if ((BB_END (then_bb)
3472 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
3473 || (BB_END (test_bb)
3474 && find_reg_note (BB_END (test_bb), REG_CROSSING_JUMP, NULL_RTX))
3475 || (BB_END (else_bb)
3476 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
3480 /* ELSE has one successor. */
3481 if (!single_succ_p (else_bb))
3484 else_succ = single_succ_edge (else_bb);
3486 /* ELSE outgoing edge is not complex. */
3487 if (else_succ->flags & EDGE_COMPLEX)
3490 /* ELSE has one predecessor. */
3491 if (!single_pred_p (else_bb))
3494 /* THEN is not EXIT. */
3495 if (then_bb->index < NUM_FIXED_BLOCKS)
3498 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
3499 note = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
3500 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
3502 else if (else_succ->dest->index < NUM_FIXED_BLOCKS
3503 || dominated_by_p (CDI_POST_DOMINATORS, then_bb,
3509 num_possible_if_blocks++;
3512 "\nIF-CASE-2 found, start %d, else %d\n",
3513 test_bb->index, else_bb->index);
3515 /* ELSE is small. */
3516 if (! cheap_bb_rtx_cost_p (else_bb, COSTS_N_INSNS (BRANCH_COST)))
3519 /* Registers set are dead, or are predicable. */
3520 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
3523 /* Conversion went ok, including moving the insns and fixing up the
3524 jump. Adjust the CFG to match. */
3526 bitmap_ior (test_bb->il.rtl->global_live_at_end,
3527 then_bb->il.rtl->global_live_at_start,
3528 else_bb->il.rtl->global_live_at_end);
3530 delete_basic_block (else_bb);
3533 num_updated_if_blocks++;
3535 /* ??? We may now fallthru from one of THEN's successors into a join
3536 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3541 /* A subroutine of dead_or_predicable called through for_each_rtx.
3542 Return 1 if a memory is found. */
3545 find_memory (rtx *px, void *data ATTRIBUTE_UNUSED)
3550 /* Used by the code above to perform the actual rtl transformations.
3551 Return TRUE if successful.
3553 TEST_BB is the block containing the conditional branch. MERGE_BB
3554 is the block containing the code to manipulate. NEW_DEST is the
3555 label TEST_BB should be branching to after the conversion.
3556 REVERSEP is true if the sense of the branch should be reversed. */
3559 dead_or_predicable (basic_block test_bb, basic_block merge_bb,
3560 basic_block other_bb, basic_block new_dest, int reversep)
3562 rtx head, end, jump, earliest = NULL_RTX, old_dest, new_label = NULL_RTX;
3564 jump = BB_END (test_bb);
3566 /* Find the extent of the real code in the merge block. */
3567 head = BB_HEAD (merge_bb);
3568 end = BB_END (merge_bb);
3570 /* If merge_bb ends with a tablejump, predicating/moving insn's
3571 into test_bb and then deleting merge_bb will result in the jumptable
3572 that follows merge_bb being removed along with merge_bb and then we
3573 get an unresolved reference to the jumptable. */
3574 if (tablejump_p (end, NULL, NULL))
3578 head = NEXT_INSN (head);
3583 head = end = NULL_RTX;
3586 head = NEXT_INSN (head);
3593 head = end = NULL_RTX;
3596 end = PREV_INSN (end);
3599 /* Disable handling dead code by conditional execution if the machine needs
3600 to do anything funny with the tests, etc. */
3601 #ifndef IFCVT_MODIFY_TESTS
3602 if (HAVE_conditional_execution)
3604 /* In the conditional execution case, we have things easy. We know
3605 the condition is reversible. We don't have to check life info
3606 because we're going to conditionally execute the code anyway.
3607 All that's left is making sure the insns involved can actually
3612 cond = cond_exec_get_condition (jump);
3616 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3618 prob_val = XEXP (prob_val, 0);
3622 enum rtx_code rev = reversed_comparison_code (cond, jump);
3625 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
3628 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
3631 if (! cond_exec_process_insns ((ce_if_block_t *)0, head, end, cond,
3640 /* In the non-conditional execution case, we have to verify that there
3641 are no trapping operations, no calls, no references to memory, and
3642 that any registers modified are dead at the branch site. */
3644 rtx insn, cond, prev;
3645 regset merge_set, tmp, test_live, test_set;
3646 struct propagate_block_info *pbi;
3647 unsigned i, fail = 0;
3650 /* Check for no calls or trapping operations. */
3651 for (insn = head; ; insn = NEXT_INSN (insn))
3657 if (may_trap_p (PATTERN (insn)))
3660 /* ??? Even non-trapping memories such as stack frame
3661 references must be avoided. For stores, we collect
3662 no lifetime info; for reads, we'd have to assert
3663 true_dependence false against every store in the
3665 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
3672 if (! any_condjump_p (jump))
3675 /* Find the extent of the conditional. */
3676 cond = noce_get_condition (jump, &earliest);
3681 MERGE_SET = set of registers set in MERGE_BB
3682 TEST_LIVE = set of registers live at EARLIEST
3683 TEST_SET = set of registers set between EARLIEST and the
3684 end of the block. */
3686 tmp = ALLOC_REG_SET (®_obstack);
3687 merge_set = ALLOC_REG_SET (®_obstack);
3688 test_live = ALLOC_REG_SET (®_obstack);
3689 test_set = ALLOC_REG_SET (®_obstack);
3691 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3692 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3693 since we've already asserted that MERGE_BB is small. */
3694 /* If we allocated new pseudos (e.g. in the conditional move
3695 expander called from noce_emit_cmove), we must resize the
3697 if (max_regno < max_reg_num ())
3699 max_regno = max_reg_num ();
3700 allocate_reg_info (max_regno, FALSE, FALSE);
3702 propagate_block (merge_bb, tmp, merge_set, merge_set, 0);
3704 /* For small register class machines, don't lengthen lifetimes of
3705 hard registers before reload. */
3706 if (SMALL_REGISTER_CLASSES && ! reload_completed)
3708 EXECUTE_IF_SET_IN_BITMAP (merge_set, 0, i, bi)
3710 if (i < FIRST_PSEUDO_REGISTER
3712 && ! global_regs[i])
3717 /* For TEST, we're interested in a range of insns, not a whole block.
3718 Moreover, we're interested in the insns live from OTHER_BB. */
3720 COPY_REG_SET (test_live, other_bb->il.rtl->global_live_at_start);
3721 pbi = init_propagate_block_info (test_bb, test_live, test_set, test_set,
3724 for (insn = jump; ; insn = prev)
3726 prev = propagate_one_insn (pbi, insn);
3727 if (insn == earliest)
3731 free_propagate_block_info (pbi);
3733 /* We can perform the transformation if
3734 MERGE_SET & (TEST_SET | TEST_LIVE)
3736 TEST_SET & merge_bb->il.rtl->global_live_at_start
3739 if (bitmap_intersect_p (test_set, merge_set)
3740 || bitmap_intersect_p (test_live, merge_set)
3741 || bitmap_intersect_p (test_set,
3742 merge_bb->il.rtl->global_live_at_start))
3746 FREE_REG_SET (merge_set);
3747 FREE_REG_SET (test_live);
3748 FREE_REG_SET (test_set);
3755 /* We don't want to use normal invert_jump or redirect_jump because
3756 we don't want to delete_insn called. Also, we want to do our own
3757 change group management. */
3759 old_dest = JUMP_LABEL (jump);
3760 if (other_bb != new_dest)
3762 new_label = block_label (new_dest);
3764 ? ! invert_jump_1 (jump, new_label)
3765 : ! redirect_jump_1 (jump, new_label))
3769 if (! apply_change_group ())
3772 if (other_bb != new_dest)
3774 redirect_jump_2 (jump, old_dest, new_label, -1, reversep);
3776 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
3779 gcov_type count, probability;
3780 count = BRANCH_EDGE (test_bb)->count;
3781 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
3782 FALLTHRU_EDGE (test_bb)->count = count;
3783 probability = BRANCH_EDGE (test_bb)->probability;
3784 BRANCH_EDGE (test_bb)->probability
3785 = FALLTHRU_EDGE (test_bb)->probability;
3786 FALLTHRU_EDGE (test_bb)->probability = probability;
3787 update_br_prob_note (test_bb);
3791 /* Move the insns out of MERGE_BB to before the branch. */
3796 if (end == BB_END (merge_bb))
3797 BB_END (merge_bb) = PREV_INSN (head);
3799 if (squeeze_notes (&head, &end))
3802 /* PR 21767: When moving insns above a conditional branch, REG_EQUAL
3803 notes might become invalid. */
3809 if (! INSN_P (insn))
3811 note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3814 set = single_set (insn);
3815 if (!set || !function_invariant_p (SET_SRC (set)))
3816 remove_note (insn, note);
3817 } while (insn != end && (insn = NEXT_INSN (insn)));
3819 reorder_insns (head, end, PREV_INSN (earliest));
3822 /* Remove the jump and edge if we can. */
3823 if (other_bb == new_dest)
3826 remove_edge (BRANCH_EDGE (test_bb));
3827 /* ??? Can't merge blocks here, as then_bb is still in use.
3828 At minimum, the merge will get done just before bb-reorder. */
3838 /* Main entry point for all if-conversion. */
3841 if_convert (int x_life_data_ok)
3846 num_possible_if_blocks = 0;
3847 num_updated_if_blocks = 0;
3848 num_true_changes = 0;
3849 life_data_ok = (x_life_data_ok != 0);
3851 if ((! targetm.cannot_modify_jumps_p ())
3852 && (!flag_reorder_blocks_and_partition || !no_new_pseudos
3853 || !targetm.have_named_sections))
3857 flow_loops_find (&loops);
3858 mark_loop_exit_edges (&loops);
3859 flow_loops_free (&loops);
3860 free_dominance_info (CDI_DOMINATORS);
3863 /* Compute postdominators if we think we'll use them. */
3864 if (HAVE_conditional_execution || life_data_ok)
3865 calculate_dominance_info (CDI_POST_DOMINATORS);
3870 /* Go through each of the basic blocks looking for things to convert. If we
3871 have conditional execution, we make multiple passes to allow us to handle
3872 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3876 cond_exec_changed_p = FALSE;
3879 #ifdef IFCVT_MULTIPLE_DUMPS
3880 if (dump_file && pass > 1)
3881 fprintf (dump_file, "\n\n========== Pass %d ==========\n", pass);
3887 while ((new_bb = find_if_header (bb, pass)))
3891 #ifdef IFCVT_MULTIPLE_DUMPS
3892 if (dump_file && cond_exec_changed_p)
3893 print_rtl_with_bb (dump_file, get_insns ());
3896 while (cond_exec_changed_p);
3898 #ifdef IFCVT_MULTIPLE_DUMPS
3900 fprintf (dump_file, "\n\n========== no more changes\n");
3903 free_dominance_info (CDI_POST_DOMINATORS);
3908 clear_aux_for_blocks ();
3910 /* Rebuild life info for basic blocks that require it. */
3911 if (num_true_changes && life_data_ok)
3913 /* If we allocated new pseudos, we must resize the array for sched1. */
3914 if (max_regno < max_reg_num ())
3916 max_regno = max_reg_num ();
3917 allocate_reg_info (max_regno, FALSE, FALSE);
3919 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES,
3920 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
3921 | PROP_KILL_DEAD_CODE);
3924 /* Write the final stats. */
3925 if (dump_file && num_possible_if_blocks > 0)
3928 "\n%d possible IF blocks searched.\n",
3929 num_possible_if_blocks);
3931 "%d IF blocks converted.\n",
3932 num_updated_if_blocks);
3934 "%d true changes made.\n\n\n",
3938 #ifdef ENABLE_CHECKING
3939 verify_flow_info ();
3944 gate_handle_if_conversion (void)
3946 return (optimize > 0);
3949 /* If-conversion and CFG cleanup. */
3951 rest_of_handle_if_conversion (void)
3953 if (flag_if_conversion)
3956 dump_flow_info (dump_file, dump_flags);
3957 cleanup_cfg (CLEANUP_EXPENSIVE);
3958 reg_scan (get_insns (), max_reg_num ());
3962 timevar_push (TV_JUMP);
3963 cleanup_cfg (CLEANUP_EXPENSIVE);
3964 reg_scan (get_insns (), max_reg_num ());
3965 timevar_pop (TV_JUMP);
3969 struct tree_opt_pass pass_rtl_ifcvt =
3972 gate_handle_if_conversion, /* gate */
3973 rest_of_handle_if_conversion, /* execute */
3976 0, /* static_pass_number */
3977 TV_IFCVT, /* tv_id */
3978 0, /* properties_required */
3979 0, /* properties_provided */
3980 0, /* properties_destroyed */
3981 0, /* todo_flags_start */
3982 TODO_dump_func, /* todo_flags_finish */
3987 gate_handle_if_after_combine (void)
3989 return (optimize > 0 && flag_if_conversion);
3993 /* Rerun if-conversion, as combine may have simplified things enough
3994 to now meet sequence length restrictions. */
3996 rest_of_handle_if_after_combine (void)
4004 struct tree_opt_pass pass_if_after_combine =
4007 gate_handle_if_after_combine, /* gate */
4008 rest_of_handle_if_after_combine, /* execute */
4011 0, /* static_pass_number */
4012 TV_IFCVT, /* tv_id */
4013 0, /* properties_required */
4014 0, /* properties_provided */
4015 0, /* properties_destroyed */
4016 0, /* todo_flags_start */
4018 TODO_ggc_collect, /* todo_flags_finish */
4024 gate_handle_if_after_reload (void)
4026 return (optimize > 0);
4030 rest_of_handle_if_after_reload (void)
4032 /* Last attempt to optimize CFG, as scheduling, peepholing and insn
4033 splitting possibly introduced more crossjumping opportunities. */
4034 cleanup_cfg (CLEANUP_EXPENSIVE
4035 | CLEANUP_UPDATE_LIFE
4036 | (flag_crossjumping ? CLEANUP_CROSSJUMP : 0));
4037 if (flag_if_conversion2)
4043 struct tree_opt_pass pass_if_after_reload =
4046 gate_handle_if_after_reload, /* gate */
4047 rest_of_handle_if_after_reload, /* execute */
4050 0, /* static_pass_number */
4051 TV_IFCVT2, /* tv_id */
4052 0, /* properties_required */
4053 0, /* properties_provided */
4054 0, /* properties_destroyed */
4055 0, /* todo_flags_start */
4057 TODO_ggc_collect, /* todo_flags_finish */