1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 #include "coretypes.h"
30 #include "insn-config.h"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
45 #ifndef HAVE_conditional_execution
46 #define HAVE_conditional_execution 0
48 #ifndef HAVE_conditional_move
49 #define HAVE_conditional_move 0
60 #ifndef HAVE_conditional_trap
61 #define HAVE_conditional_trap 0
64 #ifndef MAX_CONDITIONAL_EXECUTE
65 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
68 #define NULL_EDGE ((struct edge_def *)NULL)
69 #define NULL_BLOCK ((struct basic_block_def *)NULL)
71 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
72 static int num_possible_if_blocks;
74 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
76 static int num_updated_if_blocks;
78 /* # of changes made which require life information to be updated. */
79 static int num_true_changes;
81 /* Whether conditional execution changes were made. */
82 static int cond_exec_changed_p;
84 /* True if life data ok at present. */
85 static bool life_data_ok;
87 /* Forward references. */
88 static int count_bb_insns (basic_block);
89 static rtx first_active_insn (basic_block);
90 static rtx last_active_insn (basic_block, int);
91 static basic_block block_fallthru (basic_block);
92 static int cond_exec_process_insns (ce_if_block_t *, rtx, rtx, rtx, rtx, int);
93 static rtx cond_exec_get_condition (rtx);
94 static int cond_exec_process_if_block (ce_if_block_t *, int);
95 static rtx noce_get_condition (rtx, rtx *);
96 static int noce_operand_ok (rtx);
97 static int noce_process_if_block (ce_if_block_t *);
98 static int process_if_block (ce_if_block_t *);
99 static void merge_if_block (ce_if_block_t *);
100 static int find_cond_trap (basic_block, edge, edge);
101 static basic_block find_if_header (basic_block, int);
102 static int block_jumps_and_fallthru_p (basic_block, basic_block);
103 static int find_if_block (ce_if_block_t *);
104 static int find_if_case_1 (basic_block, edge, edge);
105 static int find_if_case_2 (basic_block, edge, edge);
106 static int find_memory (rtx *, void *);
107 static int dead_or_predicable (basic_block, basic_block, basic_block,
109 static void noce_emit_move_insn (rtx, rtx);
110 static rtx block_has_only_trap (basic_block);
111 static void mark_loop_exit_edges (void);
113 /* Sets EDGE_LOOP_EXIT flag for all loop exits. */
115 mark_loop_exit_edges (void)
121 flow_loops_find (&loops, LOOP_TREE);
122 free_dominance_info (CDI_DOMINATORS);
128 for (e = bb->succ; e; e = e->succ_next)
130 if (find_common_loop (bb->loop_father, e->dest->loop_father)
132 e->flags |= EDGE_LOOP_EXIT;
134 e->flags &= ~EDGE_LOOP_EXIT;
139 flow_loops_free (&loops);
142 /* Count the number of non-jump active insns in BB. */
145 count_bb_insns (basic_block bb)
148 rtx insn = BB_HEAD (bb);
152 if (GET_CODE (insn) == CALL_INSN || GET_CODE (insn) == INSN)
155 if (insn == BB_END (bb))
157 insn = NEXT_INSN (insn);
163 /* Return the first non-jump active insn in the basic block. */
166 first_active_insn (basic_block bb)
168 rtx insn = BB_HEAD (bb);
170 if (GET_CODE (insn) == CODE_LABEL)
172 if (insn == BB_END (bb))
174 insn = NEXT_INSN (insn);
177 while (GET_CODE (insn) == NOTE)
179 if (insn == BB_END (bb))
181 insn = NEXT_INSN (insn);
184 if (GET_CODE (insn) == JUMP_INSN)
190 /* Return the last non-jump active (non-jump) insn in the basic block. */
193 last_active_insn (basic_block bb, int skip_use_p)
195 rtx insn = BB_END (bb);
196 rtx head = BB_HEAD (bb);
198 while (GET_CODE (insn) == NOTE
199 || GET_CODE (insn) == JUMP_INSN
201 && GET_CODE (insn) == INSN
202 && GET_CODE (PATTERN (insn)) == USE))
206 insn = PREV_INSN (insn);
209 if (GET_CODE (insn) == CODE_LABEL)
215 /* Return the basic block reached by falling though the basic block BB. */
218 block_fallthru (basic_block bb)
223 e != NULL_EDGE && (e->flags & EDGE_FALLTHRU) == 0;
227 return (e) ? e->dest : NULL_BLOCK;
230 /* Go through a bunch of insns, converting them to conditional
231 execution format if possible. Return TRUE if all of the non-note
232 insns were processed. */
235 cond_exec_process_insns (ce_if_block_t *ce_info ATTRIBUTE_UNUSED,
236 /* if block information */rtx start,
237 /* first insn to look at */rtx end,
238 /* last insn to look at */rtx test,
239 /* conditional execution test */rtx prob_val,
240 /* probability of branch taken. */int mod_ok)
242 int must_be_last = FALSE;
250 for (insn = start; ; insn = NEXT_INSN (insn))
252 if (GET_CODE (insn) == NOTE)
255 if (GET_CODE (insn) != INSN && GET_CODE (insn) != CALL_INSN)
258 /* Remove USE insns that get in the way. */
259 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
261 /* ??? Ug. Actually unlinking the thing is problematic,
262 given what we'd have to coordinate with our callers. */
263 SET_INSN_DELETED (insn);
267 /* Last insn wasn't last? */
271 if (modified_in_p (test, insn))
278 /* Now build the conditional form of the instruction. */
279 pattern = PATTERN (insn);
280 xtest = copy_rtx (test);
282 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
284 if (GET_CODE (pattern) == COND_EXEC)
286 if (GET_MODE (xtest) != GET_MODE (COND_EXEC_TEST (pattern)))
289 xtest = gen_rtx_AND (GET_MODE (xtest), xtest,
290 COND_EXEC_TEST (pattern));
291 pattern = COND_EXEC_CODE (pattern);
294 pattern = gen_rtx_COND_EXEC (VOIDmode, xtest, pattern);
296 /* If the machine needs to modify the insn being conditionally executed,
297 say for example to force a constant integer operand into a temp
298 register, do so here. */
299 #ifdef IFCVT_MODIFY_INSN
300 IFCVT_MODIFY_INSN (ce_info, pattern, insn);
305 validate_change (insn, &PATTERN (insn), pattern, 1);
307 if (GET_CODE (insn) == CALL_INSN && prob_val)
308 validate_change (insn, ®_NOTES (insn),
309 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
310 REG_NOTES (insn)), 1);
320 /* Return the condition for a jump. Do not do any special processing. */
323 cond_exec_get_condition (rtx jump)
327 if (any_condjump_p (jump))
328 test_if = SET_SRC (pc_set (jump));
331 cond = XEXP (test_if, 0);
333 /* If this branches to JUMP_LABEL when the condition is false,
334 reverse the condition. */
335 if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF
336 && XEXP (XEXP (test_if, 2), 0) == JUMP_LABEL (jump))
338 enum rtx_code rev = reversed_comparison_code (cond, jump);
342 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
349 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
350 to conditional execution. Return TRUE if we were successful at
351 converting the block. */
354 cond_exec_process_if_block (ce_if_block_t * ce_info,
355 /* if block information */int do_multiple_p)
357 basic_block test_bb = ce_info->test_bb; /* last test block */
358 basic_block then_bb = ce_info->then_bb; /* THEN */
359 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
360 rtx test_expr; /* expression in IF_THEN_ELSE that is tested */
361 rtx then_start; /* first insn in THEN block */
362 rtx then_end; /* last insn + 1 in THEN block */
363 rtx else_start = NULL_RTX; /* first insn in ELSE block or NULL */
364 rtx else_end = NULL_RTX; /* last insn + 1 in ELSE block */
365 int max; /* max # of insns to convert. */
366 int then_mod_ok; /* whether conditional mods are ok in THEN */
367 rtx true_expr; /* test for else block insns */
368 rtx false_expr; /* test for then block insns */
369 rtx true_prob_val; /* probability of else block */
370 rtx false_prob_val; /* probability of then block */
372 enum rtx_code false_code;
374 /* If test is comprised of && or || elements, and we've failed at handling
375 all of them together, just use the last test if it is the special case of
376 && elements without an ELSE block. */
377 if (!do_multiple_p && ce_info->num_multiple_test_blocks)
379 if (else_bb || ! ce_info->and_and_p)
382 ce_info->test_bb = test_bb = ce_info->last_test_bb;
383 ce_info->num_multiple_test_blocks = 0;
384 ce_info->num_and_and_blocks = 0;
385 ce_info->num_or_or_blocks = 0;
388 /* Find the conditional jump to the ELSE or JOIN part, and isolate
390 test_expr = cond_exec_get_condition (BB_END (test_bb));
394 /* If the conditional jump is more than just a conditional jump,
395 then we can not do conditional execution conversion on this block. */
396 if (! onlyjump_p (BB_END (test_bb)))
399 /* Collect the bounds of where we're to search, skipping any labels, jumps
400 and notes at the beginning and end of the block. Then count the total
401 number of insns and see if it is small enough to convert. */
402 then_start = first_active_insn (then_bb);
403 then_end = last_active_insn (then_bb, TRUE);
404 n_insns = ce_info->num_then_insns = count_bb_insns (then_bb);
405 max = MAX_CONDITIONAL_EXECUTE;
410 else_start = first_active_insn (else_bb);
411 else_end = last_active_insn (else_bb, TRUE);
412 n_insns += ce_info->num_else_insns = count_bb_insns (else_bb);
418 /* Map test_expr/test_jump into the appropriate MD tests to use on
419 the conditionally executed code. */
421 true_expr = test_expr;
423 false_code = reversed_comparison_code (true_expr, BB_END (test_bb));
424 if (false_code != UNKNOWN)
425 false_expr = gen_rtx_fmt_ee (false_code, GET_MODE (true_expr),
426 XEXP (true_expr, 0), XEXP (true_expr, 1));
428 false_expr = NULL_RTX;
430 #ifdef IFCVT_MODIFY_TESTS
431 /* If the machine description needs to modify the tests, such as setting a
432 conditional execution register from a comparison, it can do so here. */
433 IFCVT_MODIFY_TESTS (ce_info, true_expr, false_expr);
435 /* See if the conversion failed. */
436 if (!true_expr || !false_expr)
440 true_prob_val = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
443 true_prob_val = XEXP (true_prob_val, 0);
444 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
447 false_prob_val = NULL_RTX;
449 /* If we have && or || tests, do them here. These tests are in the adjacent
450 blocks after the first block containing the test. */
451 if (ce_info->num_multiple_test_blocks > 0)
453 basic_block bb = test_bb;
454 basic_block last_test_bb = ce_info->last_test_bb;
464 bb = block_fallthru (bb);
465 start = first_active_insn (bb);
466 end = last_active_insn (bb, TRUE);
468 && ! cond_exec_process_insns (ce_info, start, end, false_expr,
469 false_prob_val, FALSE))
472 /* If the conditional jump is more than just a conditional jump, then
473 we can not do conditional execution conversion on this block. */
474 if (! onlyjump_p (BB_END (bb)))
477 /* Find the conditional jump and isolate the test. */
478 t = cond_exec_get_condition (BB_END (bb));
482 f = gen_rtx_fmt_ee (reverse_condition (GET_CODE (t)),
487 if (ce_info->and_and_p)
489 t = gen_rtx_AND (GET_MODE (t), true_expr, t);
490 f = gen_rtx_IOR (GET_MODE (t), false_expr, f);
494 t = gen_rtx_IOR (GET_MODE (t), true_expr, t);
495 f = gen_rtx_AND (GET_MODE (t), false_expr, f);
498 /* If the machine description needs to modify the tests, such as
499 setting a conditional execution register from a comparison, it can
501 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
502 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info, bb, t, f);
504 /* See if the conversion failed. */
512 while (bb != last_test_bb);
515 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
516 on then THEN block. */
517 then_mod_ok = (else_bb == NULL_BLOCK);
519 /* Go through the THEN and ELSE blocks converting the insns if possible
520 to conditional execution. */
524 || ! cond_exec_process_insns (ce_info, then_start, then_end,
525 false_expr, false_prob_val,
529 if (else_bb && else_end
530 && ! cond_exec_process_insns (ce_info, else_start, else_end,
531 true_expr, true_prob_val, TRUE))
534 /* If we cannot apply the changes, fail. Do not go through the normal fail
535 processing, since apply_change_group will call cancel_changes. */
536 if (! apply_change_group ())
538 #ifdef IFCVT_MODIFY_CANCEL
539 /* Cancel any machine dependent changes. */
540 IFCVT_MODIFY_CANCEL (ce_info);
545 #ifdef IFCVT_MODIFY_FINAL
546 /* Do any machine dependent final modifications. */
547 IFCVT_MODIFY_FINAL (ce_info);
550 /* Conversion succeeded. */
552 fprintf (dump_file, "%d insn%s converted to conditional execution.\n",
553 n_insns, (n_insns == 1) ? " was" : "s were");
555 /* Merge the blocks! */
556 merge_if_block (ce_info);
557 cond_exec_changed_p = TRUE;
561 #ifdef IFCVT_MODIFY_CANCEL
562 /* Cancel any machine dependent changes. */
563 IFCVT_MODIFY_CANCEL (ce_info);
570 /* Used by noce_process_if_block to communicate with its subroutines.
572 The subroutines know that A and B may be evaluated freely. They
573 know that X is a register. They should insert new instructions
574 before cond_earliest. */
581 rtx jump, cond, cond_earliest;
584 static rtx noce_emit_store_flag (struct noce_if_info *, rtx, int, int);
585 static int noce_try_move (struct noce_if_info *);
586 static int noce_try_store_flag (struct noce_if_info *);
587 static int noce_try_addcc (struct noce_if_info *);
588 static int noce_try_store_flag_constants (struct noce_if_info *);
589 static int noce_try_store_flag_mask (struct noce_if_info *);
590 static rtx noce_emit_cmove (struct noce_if_info *, rtx, enum rtx_code, rtx,
592 static int noce_try_cmove (struct noce_if_info *);
593 static int noce_try_cmove_arith (struct noce_if_info *);
594 static rtx noce_get_alt_condition (struct noce_if_info *, rtx, rtx *);
595 static int noce_try_minmax (struct noce_if_info *);
596 static int noce_try_abs (struct noce_if_info *);
597 static int noce_try_sign_mask (struct noce_if_info *);
599 /* Helper function for noce_try_store_flag*. */
602 noce_emit_store_flag (struct noce_if_info *if_info, rtx x, int reversep,
605 rtx cond = if_info->cond;
609 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
610 || ! general_operand (XEXP (cond, 1), VOIDmode));
612 /* If earliest == jump, or when the condition is complex, try to
613 build the store_flag insn directly. */
616 cond = XEXP (SET_SRC (pc_set (if_info->jump)), 0);
619 code = reversed_comparison_code (cond, if_info->jump);
621 code = GET_CODE (cond);
623 if ((if_info->cond_earliest == if_info->jump || cond_complex)
624 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
628 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
630 tmp = gen_rtx_SET (VOIDmode, x, tmp);
633 tmp = emit_insn (tmp);
635 if (recog_memoized (tmp) >= 0)
641 if_info->cond_earliest = if_info->jump;
649 /* Don't even try if the comparison operands or the mode of X are weird. */
650 if (cond_complex || !SCALAR_INT_MODE_P (GET_MODE (x)))
653 return emit_store_flag (x, code, XEXP (cond, 0),
654 XEXP (cond, 1), VOIDmode,
655 (code == LTU || code == LEU
656 || code == GEU || code == GTU), normalize);
659 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
660 X is the destination/target and Y is the value to copy. */
663 noce_emit_move_insn (rtx x, rtx y)
665 enum machine_mode outmode, inmode;
669 if (GET_CODE (x) != STRICT_LOW_PART)
671 emit_move_insn (x, y);
676 inner = XEXP (outer, 0);
677 outmode = GET_MODE (outer);
678 inmode = GET_MODE (inner);
679 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
680 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y,
681 GET_MODE_BITSIZE (inmode));
684 /* Return sequence of instructions generated by if conversion. This
685 function calls end_sequence() to end the current stream, ensures
686 that are instructions are unshared, recognizable non-jump insns.
687 On failure, this function returns a NULL_RTX. */
690 end_ifcvt_sequence (struct noce_if_info *if_info)
693 rtx seq = get_insns ();
695 set_used_flags (if_info->x);
696 set_used_flags (if_info->cond);
697 unshare_all_rtl_in_chain (seq);
700 /* Make sure that all of the instructions emitted are recognizable,
701 and that we haven't introduced a new jump instruction.
702 As an exercise for the reader, build a general mechanism that
703 allows proper placement of required clobbers. */
704 for (insn = seq; insn; insn = NEXT_INSN (insn))
705 if (GET_CODE (insn) == JUMP_INSN
706 || recog_memoized (insn) == -1)
712 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
713 "if (a == b) x = a; else x = b" into "x = b". */
716 noce_try_move (struct noce_if_info *if_info)
718 rtx cond = if_info->cond;
719 enum rtx_code code = GET_CODE (cond);
722 if (code != NE && code != EQ)
725 /* This optimization isn't valid if either A or B could be a NaN
727 if (HONOR_NANS (GET_MODE (if_info->x))
728 || HONOR_SIGNED_ZEROS (GET_MODE (if_info->x)))
731 /* Check whether the operands of the comparison are A and in
733 if ((rtx_equal_p (if_info->a, XEXP (cond, 0))
734 && rtx_equal_p (if_info->b, XEXP (cond, 1)))
735 || (rtx_equal_p (if_info->a, XEXP (cond, 1))
736 && rtx_equal_p (if_info->b, XEXP (cond, 0))))
738 y = (code == EQ) ? if_info->a : if_info->b;
740 /* Avoid generating the move if the source is the destination. */
741 if (! rtx_equal_p (if_info->x, y))
744 noce_emit_move_insn (if_info->x, y);
745 seq = end_ifcvt_sequence (if_info);
749 emit_insn_before_setloc (seq, if_info->jump,
750 INSN_LOCATOR (if_info->insn_a));
757 /* Convert "if (test) x = 1; else x = 0".
759 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
760 tried in noce_try_store_flag_constants after noce_try_cmove has had
761 a go at the conversion. */
764 noce_try_store_flag (struct noce_if_info *if_info)
769 if (GET_CODE (if_info->b) == CONST_INT
770 && INTVAL (if_info->b) == STORE_FLAG_VALUE
771 && if_info->a == const0_rtx)
773 else if (if_info->b == const0_rtx
774 && GET_CODE (if_info->a) == CONST_INT
775 && INTVAL (if_info->a) == STORE_FLAG_VALUE
776 && (reversed_comparison_code (if_info->cond, if_info->jump)
784 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
787 if (target != if_info->x)
788 noce_emit_move_insn (if_info->x, target);
790 seq = end_ifcvt_sequence (if_info);
794 emit_insn_before_setloc (seq, if_info->jump,
795 INSN_LOCATOR (if_info->insn_a));
805 /* Convert "if (test) x = a; else x = b", for A and B constant. */
808 noce_try_store_flag_constants (struct noce_if_info *if_info)
812 HOST_WIDE_INT itrue, ifalse, diff, tmp;
813 int normalize, can_reverse;
814 enum machine_mode mode;
817 && GET_CODE (if_info->a) == CONST_INT
818 && GET_CODE (if_info->b) == CONST_INT)
820 mode = GET_MODE (if_info->x);
821 ifalse = INTVAL (if_info->a);
822 itrue = INTVAL (if_info->b);
824 /* Make sure we can represent the difference between the two values. */
825 if ((itrue - ifalse > 0)
826 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
829 diff = trunc_int_for_mode (itrue - ifalse, mode);
831 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
835 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
837 else if (ifalse == 0 && exact_log2 (itrue) >= 0
838 && (STORE_FLAG_VALUE == 1
839 || BRANCH_COST >= 2))
841 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
842 && (STORE_FLAG_VALUE == 1 || BRANCH_COST >= 2))
843 normalize = 1, reversep = 1;
845 && (STORE_FLAG_VALUE == -1
846 || BRANCH_COST >= 2))
848 else if (ifalse == -1 && can_reverse
849 && (STORE_FLAG_VALUE == -1 || BRANCH_COST >= 2))
850 normalize = -1, reversep = 1;
851 else if ((BRANCH_COST >= 2 && STORE_FLAG_VALUE == -1)
859 tmp = itrue; itrue = ifalse; ifalse = tmp;
860 diff = trunc_int_for_mode (-diff, mode);
864 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
871 /* if (test) x = 3; else x = 4;
872 => x = 3 + (test == 0); */
873 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
875 target = expand_simple_binop (mode,
876 (diff == STORE_FLAG_VALUE
878 GEN_INT (ifalse), target, if_info->x, 0,
882 /* if (test) x = 8; else x = 0;
883 => x = (test != 0) << 3; */
884 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
886 target = expand_simple_binop (mode, ASHIFT,
887 target, GEN_INT (tmp), if_info->x, 0,
891 /* if (test) x = -1; else x = b;
892 => x = -(test != 0) | b; */
893 else if (itrue == -1)
895 target = expand_simple_binop (mode, IOR,
896 target, GEN_INT (ifalse), if_info->x, 0,
900 /* if (test) x = a; else x = b;
901 => x = (-(test != 0) & (b - a)) + a; */
904 target = expand_simple_binop (mode, AND,
905 target, GEN_INT (diff), if_info->x, 0,
908 target = expand_simple_binop (mode, PLUS,
909 target, GEN_INT (ifalse),
910 if_info->x, 0, OPTAB_WIDEN);
919 if (target != if_info->x)
920 noce_emit_move_insn (if_info->x, target);
922 seq = end_ifcvt_sequence (if_info);
926 emit_insn_before_setloc (seq, if_info->jump,
927 INSN_LOCATOR (if_info->insn_a));
934 /* Convert "if (test) foo++" into "foo += (test != 0)", and
935 similarly for "foo--". */
938 noce_try_addcc (struct noce_if_info *if_info)
941 int subtract, normalize;
944 && GET_CODE (if_info->a) == PLUS
945 && rtx_equal_p (XEXP (if_info->a, 0), if_info->b)
946 && (reversed_comparison_code (if_info->cond, if_info->jump)
949 rtx cond = if_info->cond;
950 enum rtx_code code = reversed_comparison_code (cond, if_info->jump);
952 /* First try to use addcc pattern. */
953 if (general_operand (XEXP (cond, 0), VOIDmode)
954 && general_operand (XEXP (cond, 1), VOIDmode))
957 target = emit_conditional_add (if_info->x, code,
962 XEXP (if_info->a, 1),
963 GET_MODE (if_info->x),
964 (code == LTU || code == GEU
965 || code == LEU || code == GTU));
968 if (target != if_info->x)
969 noce_emit_move_insn (if_info->x, target);
971 seq = end_ifcvt_sequence (if_info);
975 emit_insn_before_setloc (seq, if_info->jump,
976 INSN_LOCATOR (if_info->insn_a));
982 /* If that fails, construct conditional increment or decrement using
985 && (XEXP (if_info->a, 1) == const1_rtx
986 || XEXP (if_info->a, 1) == constm1_rtx))
989 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
990 subtract = 0, normalize = 0;
991 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
992 subtract = 1, normalize = 0;
994 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
997 target = noce_emit_store_flag (if_info,
998 gen_reg_rtx (GET_MODE (if_info->x)),
1002 target = expand_simple_binop (GET_MODE (if_info->x),
1003 subtract ? MINUS : PLUS,
1004 if_info->b, target, if_info->x,
1008 if (target != if_info->x)
1009 noce_emit_move_insn (if_info->x, target);
1011 seq = end_ifcvt_sequence (if_info);
1015 emit_insn_before_setloc (seq, if_info->jump,
1016 INSN_LOCATOR (if_info->insn_a));
1026 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1029 noce_try_store_flag_mask (struct noce_if_info *if_info)
1035 if (! no_new_pseudos
1036 && (BRANCH_COST >= 2
1037 || STORE_FLAG_VALUE == -1)
1038 && ((if_info->a == const0_rtx
1039 && rtx_equal_p (if_info->b, if_info->x))
1040 || ((reversep = (reversed_comparison_code (if_info->cond,
1043 && if_info->b == const0_rtx
1044 && rtx_equal_p (if_info->a, if_info->x))))
1047 target = noce_emit_store_flag (if_info,
1048 gen_reg_rtx (GET_MODE (if_info->x)),
1051 target = expand_simple_binop (GET_MODE (if_info->x), AND,
1053 target, if_info->x, 0,
1058 if (target != if_info->x)
1059 noce_emit_move_insn (if_info->x, target);
1061 seq = end_ifcvt_sequence (if_info);
1065 emit_insn_before_setloc (seq, if_info->jump,
1066 INSN_LOCATOR (if_info->insn_a));
1076 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1079 noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code,
1080 rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue)
1082 /* If earliest == jump, try to build the cmove insn directly.
1083 This is helpful when combine has created some complex condition
1084 (like for alpha's cmovlbs) that we can't hope to regenerate
1085 through the normal interface. */
1087 if (if_info->cond_earliest == if_info->jump)
1091 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
1092 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
1093 tmp = gen_rtx_SET (VOIDmode, x, tmp);
1096 tmp = emit_insn (tmp);
1098 if (recog_memoized (tmp) >= 0)
1110 /* Don't even try if the comparison operands are weird. */
1111 if (! general_operand (cmp_a, GET_MODE (cmp_a))
1112 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
1115 #if HAVE_conditional_move
1116 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
1117 vtrue, vfalse, GET_MODE (x),
1118 (code == LTU || code == GEU
1119 || code == LEU || code == GTU));
1121 /* We'll never get here, as noce_process_if_block doesn't call the
1122 functions involved. Ifdef code, however, should be discouraged
1123 because it leads to typos in the code not selected. However,
1124 emit_conditional_move won't exist either. */
1129 /* Try only simple constants and registers here. More complex cases
1130 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1131 has had a go at it. */
1134 noce_try_cmove (struct noce_if_info *if_info)
1139 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
1140 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
1144 code = GET_CODE (if_info->cond);
1145 target = noce_emit_cmove (if_info, if_info->x, code,
1146 XEXP (if_info->cond, 0),
1147 XEXP (if_info->cond, 1),
1148 if_info->a, if_info->b);
1152 if (target != if_info->x)
1153 noce_emit_move_insn (if_info->x, target);
1155 seq = end_ifcvt_sequence (if_info);
1159 emit_insn_before_setloc (seq, if_info->jump,
1160 INSN_LOCATOR (if_info->insn_a));
1173 /* Try more complex cases involving conditional_move. */
1176 noce_try_cmove_arith (struct noce_if_info *if_info)
1186 /* A conditional move from two memory sources is equivalent to a
1187 conditional on their addresses followed by a load. Don't do this
1188 early because it'll screw alias analysis. Note that we've
1189 already checked for no side effects. */
1190 if (! no_new_pseudos && cse_not_expected
1191 && MEM_P (a) && MEM_P (b)
1192 && BRANCH_COST >= 5)
1196 x = gen_reg_rtx (Pmode);
1200 /* ??? We could handle this if we knew that a load from A or B could
1201 not fault. This is also true if we've already loaded
1202 from the address along the path from ENTRY. */
1203 else if (may_trap_p (a) || may_trap_p (b))
1206 /* if (test) x = a + b; else x = c - d;
1213 code = GET_CODE (if_info->cond);
1214 insn_a = if_info->insn_a;
1215 insn_b = if_info->insn_b;
1217 /* Possibly rearrange operands to make things come out more natural. */
1218 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1221 if (rtx_equal_p (b, x))
1223 else if (general_operand (b, GET_MODE (b)))
1228 code = reversed_comparison_code (if_info->cond, if_info->jump);
1229 tmp = a, a = b, b = tmp;
1230 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1236 /* If either operand is complex, load it into a register first.
1237 The best way to do this is to copy the original insn. In this
1238 way we preserve any clobbers etc that the insn may have had.
1239 This is of course not possible in the IS_MEM case. */
1240 if (! general_operand (a, GET_MODE (a)))
1245 goto end_seq_and_fail;
1249 tmp = gen_reg_rtx (GET_MODE (a));
1250 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1253 goto end_seq_and_fail;
1256 a = gen_reg_rtx (GET_MODE (a));
1257 tmp = copy_rtx (insn_a);
1258 set = single_set (tmp);
1260 tmp = emit_insn (PATTERN (tmp));
1262 if (recog_memoized (tmp) < 0)
1263 goto end_seq_and_fail;
1265 if (! general_operand (b, GET_MODE (b)))
1270 goto end_seq_and_fail;
1274 tmp = gen_reg_rtx (GET_MODE (b));
1275 tmp = emit_insn (gen_rtx_SET (VOIDmode,
1280 goto end_seq_and_fail;
1283 b = gen_reg_rtx (GET_MODE (b));
1284 tmp = copy_rtx (insn_b);
1285 set = single_set (tmp);
1287 tmp = emit_insn (PATTERN (tmp));
1289 if (recog_memoized (tmp) < 0)
1290 goto end_seq_and_fail;
1293 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1294 XEXP (if_info->cond, 1), a, b);
1297 goto end_seq_and_fail;
1299 /* If we're handling a memory for above, emit the load now. */
1302 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1304 /* Copy over flags as appropriate. */
1305 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1306 MEM_VOLATILE_P (tmp) = 1;
1307 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1308 MEM_IN_STRUCT_P (tmp) = 1;
1309 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1310 MEM_SCALAR_P (tmp) = 1;
1311 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1312 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1314 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1316 noce_emit_move_insn (if_info->x, tmp);
1318 else if (target != x)
1319 noce_emit_move_insn (x, target);
1321 tmp = end_ifcvt_sequence (if_info);
1325 emit_insn_before_setloc (tmp, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1333 /* For most cases, the simplified condition we found is the best
1334 choice, but this is not the case for the min/max/abs transforms.
1335 For these we wish to know that it is A or B in the condition. */
1338 noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
1341 rtx cond, set, insn;
1344 /* If target is already mentioned in the known condition, return it. */
1345 if (reg_mentioned_p (target, if_info->cond))
1347 *earliest = if_info->cond_earliest;
1348 return if_info->cond;
1351 set = pc_set (if_info->jump);
1352 cond = XEXP (SET_SRC (set), 0);
1354 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1355 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1357 /* If we're looking for a constant, try to make the conditional
1358 have that constant in it. There are two reasons why it may
1359 not have the constant we want:
1361 1. GCC may have needed to put the constant in a register, because
1362 the target can't compare directly against that constant. For
1363 this case, we look for a SET immediately before the comparison
1364 that puts a constant in that register.
1366 2. GCC may have canonicalized the conditional, for example
1367 replacing "if x < 4" with "if x <= 3". We can undo that (or
1368 make equivalent types of changes) to get the constants we need
1369 if they're off by one in the right direction. */
1371 if (GET_CODE (target) == CONST_INT)
1373 enum rtx_code code = GET_CODE (if_info->cond);
1374 rtx op_a = XEXP (if_info->cond, 0);
1375 rtx op_b = XEXP (if_info->cond, 1);
1378 /* First, look to see if we put a constant in a register. */
1379 prev_insn = PREV_INSN (if_info->cond_earliest);
1381 && INSN_P (prev_insn)
1382 && GET_CODE (PATTERN (prev_insn)) == SET)
1384 rtx src = find_reg_equal_equiv_note (prev_insn);
1386 src = SET_SRC (PATTERN (prev_insn));
1387 if (GET_CODE (src) == CONST_INT)
1389 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1391 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1394 if (GET_CODE (op_a) == CONST_INT)
1399 code = swap_condition (code);
1404 /* Now, look to see if we can get the right constant by
1405 adjusting the conditional. */
1406 if (GET_CODE (op_b) == CONST_INT)
1408 HOST_WIDE_INT desired_val = INTVAL (target);
1409 HOST_WIDE_INT actual_val = INTVAL (op_b);
1414 if (actual_val == desired_val + 1)
1417 op_b = GEN_INT (desired_val);
1421 if (actual_val == desired_val - 1)
1424 op_b = GEN_INT (desired_val);
1428 if (actual_val == desired_val - 1)
1431 op_b = GEN_INT (desired_val);
1435 if (actual_val == desired_val + 1)
1438 op_b = GEN_INT (desired_val);
1446 /* If we made any changes, generate a new conditional that is
1447 equivalent to what we started with, but has the right
1449 if (code != GET_CODE (if_info->cond)
1450 || op_a != XEXP (if_info->cond, 0)
1451 || op_b != XEXP (if_info->cond, 1))
1453 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1454 *earliest = if_info->cond_earliest;
1459 cond = canonicalize_condition (if_info->jump, cond, reverse,
1460 earliest, target, false);
1461 if (! cond || ! reg_mentioned_p (target, cond))
1464 /* We almost certainly searched back to a different place.
1465 Need to re-verify correct lifetimes. */
1467 /* X may not be mentioned in the range (cond_earliest, jump]. */
1468 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1469 if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
1472 /* A and B may not be modified in the range [cond_earliest, jump). */
1473 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1475 && (modified_in_p (if_info->a, insn)
1476 || modified_in_p (if_info->b, insn)))
1482 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1485 noce_try_minmax (struct noce_if_info *if_info)
1487 rtx cond, earliest, target, seq;
1488 enum rtx_code code, op;
1491 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1495 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1496 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1497 to get the target to tell us... */
1498 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1499 || HONOR_NANS (GET_MODE (if_info->x)))
1502 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1506 /* Verify the condition is of the form we expect, and canonicalize
1507 the comparison code. */
1508 code = GET_CODE (cond);
1509 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1511 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1514 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1516 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1518 code = swap_condition (code);
1523 /* Determine what sort of operation this is. Note that the code is for
1524 a taken branch, so the code->operation mapping appears backwards. */
1557 target = expand_simple_binop (GET_MODE (if_info->x), op,
1558 if_info->a, if_info->b,
1559 if_info->x, unsignedp, OPTAB_WIDEN);
1565 if (target != if_info->x)
1566 noce_emit_move_insn (if_info->x, target);
1568 seq = end_ifcvt_sequence (if_info);
1572 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1573 if_info->cond = cond;
1574 if_info->cond_earliest = earliest;
1579 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1582 noce_try_abs (struct noce_if_info *if_info)
1584 rtx cond, earliest, target, seq, a, b, c;
1587 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1591 /* Recognize A and B as constituting an ABS or NABS. */
1594 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1596 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1598 c = a; a = b; b = c;
1604 cond = noce_get_alt_condition (if_info, b, &earliest);
1608 /* Verify the condition is of the form we expect. */
1609 if (rtx_equal_p (XEXP (cond, 0), b))
1611 else if (rtx_equal_p (XEXP (cond, 1), b))
1616 /* Verify that C is zero. Search backward through the block for
1617 a REG_EQUAL note if necessary. */
1620 rtx insn, note = NULL;
1621 for (insn = earliest;
1622 insn != BB_HEAD (if_info->test_bb);
1623 insn = PREV_INSN (insn))
1625 && ((note = find_reg_note (insn, REG_EQUAL, c))
1626 || (note = find_reg_note (insn, REG_EQUIV, c))))
1633 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1634 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1635 c = get_pool_constant (XEXP (c, 0));
1637 /* Work around funny ideas get_condition has wrt canonicalization.
1638 Note that these rtx constants are known to be CONST_INT, and
1639 therefore imply integer comparisons. */
1640 if (c == constm1_rtx && GET_CODE (cond) == GT)
1642 else if (c == const1_rtx && GET_CODE (cond) == LT)
1644 else if (c != CONST0_RTX (GET_MODE (b)))
1647 /* Determine what sort of operation this is. */
1648 switch (GET_CODE (cond))
1667 target = expand_abs_nojump (GET_MODE (if_info->x), b, if_info->x, 1);
1669 /* ??? It's a quandary whether cmove would be better here, especially
1670 for integers. Perhaps combine will clean things up. */
1671 if (target && negate)
1672 target = expand_simple_unop (GET_MODE (target), NEG, target, if_info->x, 0);
1680 if (target != if_info->x)
1681 noce_emit_move_insn (if_info->x, target);
1683 seq = end_ifcvt_sequence (if_info);
1687 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1688 if_info->cond = cond;
1689 if_info->cond_earliest = earliest;
1694 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1697 noce_try_sign_mask (struct noce_if_info *if_info)
1699 rtx cond, t, m, c, seq;
1700 enum machine_mode mode;
1706 cond = if_info->cond;
1707 code = GET_CODE (cond);
1712 if (if_info->a == const0_rtx)
1714 if ((code == LT && c == const0_rtx)
1715 || (code == LE && c == constm1_rtx))
1718 else if (if_info->b == const0_rtx)
1720 if ((code == GE && c == const0_rtx)
1721 || (code == GT && c == constm1_rtx))
1725 if (! t || side_effects_p (t))
1728 /* We currently don't handle different modes. */
1729 mode = GET_MODE (t);
1730 if (GET_MODE (m) != mode)
1733 /* This is only profitable if T is cheap. */
1734 if (rtx_cost (t, SET) >= COSTS_N_INSNS (2))
1738 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1739 "(signed) m >> 31" directly. This benefits targets with specialized
1740 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1741 m = emit_store_flag (gen_reg_rtx (mode), LT, m, const0_rtx, mode, 0, -1);
1742 t = m ? expand_binop (mode, and_optab, m, t, NULL_RTX, 0, OPTAB_DIRECT)
1751 noce_emit_move_insn (if_info->x, t);
1753 seq = end_ifcvt_sequence (if_info);
1757 emit_insn_before_setloc (seq, if_info->jump, INSN_LOCATOR (if_info->insn_a));
1762 /* Similar to get_condition, only the resulting condition must be
1763 valid at JUMP, instead of at EARLIEST. */
1766 noce_get_condition (rtx jump, rtx *earliest)
1768 rtx cond, set, tmp, insn;
1771 if (! any_condjump_p (jump))
1774 set = pc_set (jump);
1776 /* If this branches to JUMP_LABEL when the condition is false,
1777 reverse the condition. */
1778 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1779 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
1781 /* If the condition variable is a register and is MODE_INT, accept it. */
1783 cond = XEXP (SET_SRC (set), 0);
1784 tmp = XEXP (cond, 0);
1785 if (REG_P (tmp) && GET_MODE_CLASS (GET_MODE (tmp)) == MODE_INT)
1790 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
1791 GET_MODE (cond), tmp, XEXP (cond, 1));
1795 /* Otherwise, fall back on canonicalize_condition to do the dirty
1796 work of manipulating MODE_CC values and COMPARE rtx codes. */
1798 tmp = canonicalize_condition (jump, cond, reverse, earliest, NULL_RTX,
1803 /* We are going to insert code before JUMP, not before EARLIEST.
1804 We must therefore be certain that the given condition is valid
1805 at JUMP by virtue of not having been modified since. */
1806 for (insn = *earliest; insn != jump; insn = NEXT_INSN (insn))
1807 if (INSN_P (insn) && modified_in_p (tmp, insn))
1812 /* The condition was modified. See if we can get a partial result
1813 that doesn't follow all the reversals. Perhaps combine can fold
1814 them together later. */
1815 tmp = XEXP (tmp, 0);
1816 if (!REG_P (tmp) || GET_MODE_CLASS (GET_MODE (tmp)) != MODE_INT)
1818 tmp = canonicalize_condition (jump, cond, reverse, earliest, tmp,
1823 /* For sanity's sake, re-validate the new result. */
1824 for (insn = *earliest; insn != jump; insn = NEXT_INSN (insn))
1825 if (INSN_P (insn) && modified_in_p (tmp, insn))
1831 /* Return true if OP is ok for if-then-else processing. */
1834 noce_operand_ok (rtx op)
1836 /* We special-case memories, so handle any of them with
1837 no address side effects. */
1839 return ! side_effects_p (XEXP (op, 0));
1841 if (side_effects_p (op))
1844 return ! may_trap_p (op);
1847 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1848 without using conditional execution. Return TRUE if we were
1849 successful at converting the block. */
1852 noce_process_if_block (struct ce_if_block * ce_info)
1854 basic_block test_bb = ce_info->test_bb; /* test block */
1855 basic_block then_bb = ce_info->then_bb; /* THEN */
1856 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
1857 struct noce_if_info if_info;
1860 rtx orig_x, x, a, b;
1863 /* We're looking for patterns of the form
1865 (1) if (...) x = a; else x = b;
1866 (2) x = b; if (...) x = a;
1867 (3) if (...) x = a; // as if with an initial x = x.
1869 The later patterns require jumps to be more expensive.
1871 ??? For future expansion, look for multiple X in such patterns. */
1873 /* If test is comprised of && or || elements, don't handle it unless it is
1874 the special case of && elements without an ELSE block. */
1875 if (ce_info->num_multiple_test_blocks)
1877 if (else_bb || ! ce_info->and_and_p)
1880 ce_info->test_bb = test_bb = ce_info->last_test_bb;
1881 ce_info->num_multiple_test_blocks = 0;
1882 ce_info->num_and_and_blocks = 0;
1883 ce_info->num_or_or_blocks = 0;
1886 /* If this is not a standard conditional jump, we can't parse it. */
1887 jump = BB_END (test_bb);
1888 cond = noce_get_condition (jump, &if_info.cond_earliest);
1892 /* If the conditional jump is more than just a conditional
1893 jump, then we can not do if-conversion on this block. */
1894 if (! onlyjump_p (jump))
1897 /* We must be comparing objects whose modes imply the size. */
1898 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
1901 /* Look for one of the potential sets. */
1902 insn_a = first_active_insn (then_bb);
1904 || insn_a != last_active_insn (then_bb, FALSE)
1905 || (set_a = single_set (insn_a)) == NULL_RTX)
1908 x = SET_DEST (set_a);
1909 a = SET_SRC (set_a);
1911 /* Look for the other potential set. Make sure we've got equivalent
1913 /* ??? This is overconservative. Storing to two different mems is
1914 as easy as conditionally computing the address. Storing to a
1915 single mem merely requires a scratch memory to use as one of the
1916 destination addresses; often the memory immediately below the
1917 stack pointer is available for this. */
1921 insn_b = first_active_insn (else_bb);
1923 || insn_b != last_active_insn (else_bb, FALSE)
1924 || (set_b = single_set (insn_b)) == NULL_RTX
1925 || ! rtx_equal_p (x, SET_DEST (set_b)))
1930 insn_b = prev_nonnote_insn (if_info.cond_earliest);
1931 /* We're going to be moving the evaluation of B down from above
1932 COND_EARLIEST to JUMP. Make sure the relevant data is still
1935 || GET_CODE (insn_b) != INSN
1936 || (set_b = single_set (insn_b)) == NULL_RTX
1937 || ! rtx_equal_p (x, SET_DEST (set_b))
1938 || reg_overlap_mentioned_p (x, SET_SRC (set_b))
1939 || modified_between_p (SET_SRC (set_b),
1940 PREV_INSN (if_info.cond_earliest), jump)
1941 /* Likewise with X. In particular this can happen when
1942 noce_get_condition looks farther back in the instruction
1943 stream than one might expect. */
1944 || reg_overlap_mentioned_p (x, cond)
1945 || reg_overlap_mentioned_p (x, a)
1946 || modified_between_p (x, PREV_INSN (if_info.cond_earliest), jump))
1947 insn_b = set_b = NULL_RTX;
1950 /* If x has side effects then only the if-then-else form is safe to
1951 convert. But even in that case we would need to restore any notes
1952 (such as REG_INC) at then end. That can be tricky if
1953 noce_emit_move_insn expands to more than one insn, so disable the
1954 optimization entirely for now if there are side effects. */
1955 if (side_effects_p (x))
1958 b = (set_b ? SET_SRC (set_b) : x);
1960 /* Only operate on register destinations, and even then avoid extending
1961 the lifetime of hard registers on small register class machines. */
1964 || (SMALL_REGISTER_CLASSES
1965 && REGNO (x) < FIRST_PSEUDO_REGISTER))
1967 if (no_new_pseudos || GET_MODE (x) == BLKmode)
1969 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
1970 ? XEXP (x, 0) : x));
1973 /* Don't operate on sources that may trap or are volatile. */
1974 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
1977 /* Set up the info block for our subroutines. */
1978 if_info.test_bb = test_bb;
1979 if_info.cond = cond;
1980 if_info.jump = jump;
1981 if_info.insn_a = insn_a;
1982 if_info.insn_b = insn_b;
1987 /* Try optimizations in some approximation of a useful order. */
1988 /* ??? Should first look to see if X is live incoming at all. If it
1989 isn't, we don't need anything but an unconditional set. */
1991 /* Look and see if A and B are really the same. Avoid creating silly
1992 cmove constructs that no one will fix up later. */
1993 if (rtx_equal_p (a, b))
1995 /* If we have an INSN_B, we don't have to create any new rtl. Just
1996 move the instruction that we already have. If we don't have an
1997 INSN_B, that means that A == X, and we've got a noop move. In
1998 that case don't do anything and let the code below delete INSN_A. */
1999 if (insn_b && else_bb)
2003 if (else_bb && insn_b == BB_END (else_bb))
2004 BB_END (else_bb) = PREV_INSN (insn_b);
2005 reorder_insns (insn_b, insn_b, PREV_INSN (jump));
2007 /* If there was a REG_EQUAL note, delete it since it may have been
2008 true due to this insn being after a jump. */
2009 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
2010 remove_note (insn_b, note);
2014 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2015 x must be executed twice. */
2016 else if (insn_b && side_effects_p (orig_x))
2023 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2024 for most optimizations if writing to x may trap, i.e. it's a memory
2025 other than a static var or a stack slot. */
2028 && ! MEM_NOTRAP_P (orig_x)
2029 && rtx_addr_can_trap_p (XEXP (orig_x, 0)))
2031 if (HAVE_conditional_move)
2033 if (noce_try_cmove (&if_info))
2035 if (! HAVE_conditional_execution
2036 && noce_try_cmove_arith (&if_info))
2042 if (noce_try_move (&if_info))
2044 if (noce_try_store_flag (&if_info))
2046 if (noce_try_minmax (&if_info))
2048 if (noce_try_abs (&if_info))
2050 if (HAVE_conditional_move
2051 && noce_try_cmove (&if_info))
2053 if (! HAVE_conditional_execution)
2055 if (noce_try_store_flag_constants (&if_info))
2057 if (noce_try_addcc (&if_info))
2059 if (noce_try_store_flag_mask (&if_info))
2061 if (HAVE_conditional_move
2062 && noce_try_cmove_arith (&if_info))
2064 if (noce_try_sign_mask (&if_info))
2071 /* The original sets may now be killed. */
2072 delete_insn (insn_a);
2074 /* Several special cases here: First, we may have reused insn_b above,
2075 in which case insn_b is now NULL. Second, we want to delete insn_b
2076 if it came from the ELSE block, because follows the now correct
2077 write that appears in the TEST block. However, if we got insn_b from
2078 the TEST block, it may in fact be loading data needed for the comparison.
2079 We'll let life_analysis remove the insn if it's really dead. */
2080 if (insn_b && else_bb)
2081 delete_insn (insn_b);
2083 /* The new insns will have been inserted immediately before the jump. We
2084 should be able to remove the jump with impunity, but the condition itself
2085 may have been modified by gcse to be shared across basic blocks. */
2088 /* If we used a temporary, fix it up now. */
2092 noce_emit_move_insn (orig_x, x);
2093 insn_b = get_insns ();
2094 set_used_flags (orig_x);
2095 unshare_all_rtl_in_chain (insn_b);
2098 emit_insn_after_setloc (insn_b, BB_END (test_bb), INSN_LOCATOR (insn_a));
2101 /* Merge the blocks! */
2102 merge_if_block (ce_info);
2107 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2108 straight line code. Return true if successful. */
2111 process_if_block (struct ce_if_block * ce_info)
2113 if (! reload_completed
2114 && noce_process_if_block (ce_info))
2117 if (HAVE_conditional_execution && reload_completed)
2119 /* If we have && and || tests, try to first handle combining the && and
2120 || tests into the conditional code, and if that fails, go back and
2121 handle it without the && and ||, which at present handles the && case
2122 if there was no ELSE block. */
2123 if (cond_exec_process_if_block (ce_info, TRUE))
2126 if (ce_info->num_multiple_test_blocks)
2130 if (cond_exec_process_if_block (ce_info, FALSE))
2138 /* Merge the blocks and mark for local life update. */
2141 merge_if_block (struct ce_if_block * ce_info)
2143 basic_block test_bb = ce_info->test_bb; /* last test block */
2144 basic_block then_bb = ce_info->then_bb; /* THEN */
2145 basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
2146 basic_block join_bb = ce_info->join_bb; /* join block */
2147 basic_block combo_bb;
2149 /* All block merging is done into the lower block numbers. */
2153 /* Merge any basic blocks to handle && and || subtests. Each of
2154 the blocks are on the fallthru path from the predecessor block. */
2155 if (ce_info->num_multiple_test_blocks > 0)
2157 basic_block bb = test_bb;
2158 basic_block last_test_bb = ce_info->last_test_bb;
2159 basic_block fallthru = block_fallthru (bb);
2164 fallthru = block_fallthru (bb);
2165 merge_blocks (combo_bb, bb);
2168 while (bb != last_test_bb);
2171 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2172 label, but it might if there were || tests. That label's count should be
2173 zero, and it normally should be removed. */
2177 if (combo_bb->global_live_at_end)
2178 COPY_REG_SET (combo_bb->global_live_at_end,
2179 then_bb->global_live_at_end);
2180 merge_blocks (combo_bb, then_bb);
2184 /* The ELSE block, if it existed, had a label. That label count
2185 will almost always be zero, but odd things can happen when labels
2186 get their addresses taken. */
2189 merge_blocks (combo_bb, else_bb);
2193 /* If there was no join block reported, that means it was not adjacent
2194 to the others, and so we cannot merge them. */
2198 rtx last = BB_END (combo_bb);
2200 /* The outgoing edge for the current COMBO block should already
2201 be correct. Verify this. */
2202 if (combo_bb->succ == NULL_EDGE)
2204 if (find_reg_note (last, REG_NORETURN, NULL))
2206 else if (GET_CODE (last) == INSN
2207 && GET_CODE (PATTERN (last)) == TRAP_IF
2208 && TRAP_CONDITION (PATTERN (last)) == const_true_rtx)
2214 /* There should still be something at the end of the THEN or ELSE
2215 blocks taking us to our final destination. */
2216 else if (GET_CODE (last) == JUMP_INSN)
2218 else if (combo_bb->succ->dest == EXIT_BLOCK_PTR
2219 && GET_CODE (last) == CALL_INSN
2220 && SIBLING_CALL_P (last))
2222 else if ((combo_bb->succ->flags & EDGE_EH)
2223 && can_throw_internal (last))
2229 /* The JOIN block may have had quite a number of other predecessors too.
2230 Since we've already merged the TEST, THEN and ELSE blocks, we should
2231 have only one remaining edge from our if-then-else diamond. If there
2232 is more than one remaining edge, it must come from elsewhere. There
2233 may be zero incoming edges if the THEN block didn't actually join
2234 back up (as with a call to abort). */
2235 else if ((join_bb->pred == NULL
2236 || join_bb->pred->pred_next == NULL)
2237 && join_bb != EXIT_BLOCK_PTR)
2239 /* We can merge the JOIN. */
2240 if (combo_bb->global_live_at_end)
2241 COPY_REG_SET (combo_bb->global_live_at_end,
2242 join_bb->global_live_at_end);
2244 merge_blocks (combo_bb, join_bb);
2249 /* We cannot merge the JOIN. */
2251 /* The outgoing edge for the current COMBO block should already
2252 be correct. Verify this. */
2253 if (combo_bb->succ->succ_next != NULL_EDGE
2254 || combo_bb->succ->dest != join_bb)
2257 /* Remove the jump and cruft from the end of the COMBO block. */
2258 if (join_bb != EXIT_BLOCK_PTR)
2259 tidy_fallthru_edge (combo_bb->succ);
2262 num_updated_if_blocks++;
2265 /* Find a block ending in a simple IF condition and try to transform it
2266 in some way. When converting a multi-block condition, put the new code
2267 in the first such block and delete the rest. Return a pointer to this
2268 first block if some transformation was done. Return NULL otherwise. */
2271 find_if_header (basic_block test_bb, int pass)
2273 ce_if_block_t ce_info;
2277 /* The kind of block we're looking for has exactly two successors. */
2278 if ((then_edge = test_bb->succ) == NULL_EDGE
2279 || (else_edge = then_edge->succ_next) == NULL_EDGE
2280 || else_edge->succ_next != NULL_EDGE)
2283 /* Neither edge should be abnormal. */
2284 if ((then_edge->flags & EDGE_COMPLEX)
2285 || (else_edge->flags & EDGE_COMPLEX))
2288 /* Nor exit the loop. */
2289 if ((then_edge->flags & EDGE_LOOP_EXIT)
2290 || (else_edge->flags & EDGE_LOOP_EXIT))
2293 /* The THEN edge is canonically the one that falls through. */
2294 if (then_edge->flags & EDGE_FALLTHRU)
2296 else if (else_edge->flags & EDGE_FALLTHRU)
2299 else_edge = then_edge;
2303 /* Otherwise this must be a multiway branch of some sort. */
2306 memset (&ce_info, '\0', sizeof (ce_info));
2307 ce_info.test_bb = test_bb;
2308 ce_info.then_bb = then_edge->dest;
2309 ce_info.else_bb = else_edge->dest;
2310 ce_info.pass = pass;
2312 #ifdef IFCVT_INIT_EXTRA_FIELDS
2313 IFCVT_INIT_EXTRA_FIELDS (&ce_info);
2316 if (find_if_block (&ce_info))
2319 if (HAVE_trap && HAVE_conditional_trap
2320 && find_cond_trap (test_bb, then_edge, else_edge))
2323 if (dom_computed[CDI_POST_DOMINATORS] >= DOM_NO_FAST_QUERY
2324 && (! HAVE_conditional_execution || reload_completed))
2326 if (find_if_case_1 (test_bb, then_edge, else_edge))
2328 if (find_if_case_2 (test_bb, then_edge, else_edge))
2336 fprintf (dump_file, "Conversion succeeded on pass %d.\n", pass);
2337 return ce_info.test_bb;
2340 /* Return true if a block has two edges, one of which falls through to the next
2341 block, and the other jumps to a specific block, so that we can tell if the
2342 block is part of an && test or an || test. Returns either -1 or the number
2343 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2346 block_jumps_and_fallthru_p (basic_block cur_bb, basic_block target_bb)
2349 int fallthru_p = FALSE;
2355 if (!cur_bb || !target_bb)
2358 /* If no edges, obviously it doesn't jump or fallthru. */
2359 if (cur_bb->succ == NULL_EDGE)
2362 for (cur_edge = cur_bb->succ;
2363 cur_edge != NULL_EDGE;
2364 cur_edge = cur_edge->succ_next)
2366 if (cur_edge->flags & EDGE_COMPLEX)
2367 /* Anything complex isn't what we want. */
2370 else if (cur_edge->flags & EDGE_FALLTHRU)
2373 else if (cur_edge->dest == target_bb)
2380 if ((jump_p & fallthru_p) == 0)
2383 /* Don't allow calls in the block, since this is used to group && and ||
2384 together for conditional execution support. ??? we should support
2385 conditional execution support across calls for IA-64 some day, but
2386 for now it makes the code simpler. */
2387 end = BB_END (cur_bb);
2388 insn = BB_HEAD (cur_bb);
2390 while (insn != NULL_RTX)
2392 if (GET_CODE (insn) == CALL_INSN)
2396 && GET_CODE (insn) != JUMP_INSN
2397 && GET_CODE (PATTERN (insn)) != USE
2398 && GET_CODE (PATTERN (insn)) != CLOBBER)
2404 insn = NEXT_INSN (insn);
2410 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2411 block. If so, we'll try to convert the insns to not require the branch.
2412 Return TRUE if we were successful at converting the block. */
2415 find_if_block (struct ce_if_block * ce_info)
2417 basic_block test_bb = ce_info->test_bb;
2418 basic_block then_bb = ce_info->then_bb;
2419 basic_block else_bb = ce_info->else_bb;
2420 basic_block join_bb = NULL_BLOCK;
2421 edge then_succ = then_bb->succ;
2422 edge else_succ = else_bb->succ;
2423 int then_predecessors;
2424 int else_predecessors;
2428 ce_info->last_test_bb = test_bb;
2430 /* Discover if any fall through predecessors of the current test basic block
2431 were && tests (which jump to the else block) or || tests (which jump to
2433 if (HAVE_conditional_execution && reload_completed
2434 && test_bb->pred != NULL_EDGE
2435 && test_bb->pred->pred_next == NULL_EDGE
2436 && test_bb->pred->flags == EDGE_FALLTHRU)
2438 basic_block bb = test_bb->pred->src;
2439 basic_block target_bb;
2440 int max_insns = MAX_CONDITIONAL_EXECUTE;
2443 /* Determine if the preceding block is an && or || block. */
2444 if ((n_insns = block_jumps_and_fallthru_p (bb, else_bb)) >= 0)
2446 ce_info->and_and_p = TRUE;
2447 target_bb = else_bb;
2449 else if ((n_insns = block_jumps_and_fallthru_p (bb, then_bb)) >= 0)
2451 ce_info->and_and_p = FALSE;
2452 target_bb = then_bb;
2455 target_bb = NULL_BLOCK;
2457 if (target_bb && n_insns <= max_insns)
2459 int total_insns = 0;
2462 ce_info->last_test_bb = test_bb;
2464 /* Found at least one && or || block, look for more. */
2467 ce_info->test_bb = test_bb = bb;
2468 total_insns += n_insns;
2471 if (bb->pred == NULL_EDGE || bb->pred->pred_next != NULL_EDGE)
2475 n_insns = block_jumps_and_fallthru_p (bb, target_bb);
2477 while (n_insns >= 0 && (total_insns + n_insns) <= max_insns);
2479 ce_info->num_multiple_test_blocks = blocks;
2480 ce_info->num_multiple_test_insns = total_insns;
2482 if (ce_info->and_and_p)
2483 ce_info->num_and_and_blocks = blocks;
2485 ce_info->num_or_or_blocks = blocks;
2489 /* Count the number of edges the THEN and ELSE blocks have. */
2490 then_predecessors = 0;
2491 for (cur_edge = then_bb->pred;
2492 cur_edge != NULL_EDGE;
2493 cur_edge = cur_edge->pred_next)
2495 then_predecessors++;
2496 if (cur_edge->flags & EDGE_COMPLEX)
2500 else_predecessors = 0;
2501 for (cur_edge = else_bb->pred;
2502 cur_edge != NULL_EDGE;
2503 cur_edge = cur_edge->pred_next)
2505 else_predecessors++;
2506 if (cur_edge->flags & EDGE_COMPLEX)
2510 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2511 other than any || blocks which jump to the THEN block. */
2512 if ((then_predecessors - ce_info->num_or_or_blocks) != 1)
2515 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2516 if (then_succ != NULL_EDGE
2517 && (then_succ->succ_next != NULL_EDGE
2518 || (then_succ->flags & EDGE_COMPLEX)
2519 || (flow2_completed && tablejump_p (BB_END (then_bb), NULL, NULL))))
2522 /* If the THEN block has no successors, conditional execution can still
2523 make a conditional call. Don't do this unless the ELSE block has
2524 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2525 Check for the last insn of the THEN block being an indirect jump, which
2526 is listed as not having any successors, but confuses the rest of the CE
2527 code processing. ??? we should fix this in the future. */
2528 if (then_succ == NULL)
2530 if (else_bb->pred->pred_next == NULL_EDGE)
2532 rtx last_insn = BB_END (then_bb);
2535 && GET_CODE (last_insn) == NOTE
2536 && last_insn != BB_HEAD (then_bb))
2537 last_insn = PREV_INSN (last_insn);
2540 && GET_CODE (last_insn) == JUMP_INSN
2541 && ! simplejump_p (last_insn))
2545 else_bb = NULL_BLOCK;
2551 /* If the THEN block's successor is the other edge out of the TEST block,
2552 then we have an IF-THEN combo without an ELSE. */
2553 else if (then_succ->dest == else_bb)
2556 else_bb = NULL_BLOCK;
2559 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2560 has exactly one predecessor and one successor, and the outgoing edge
2561 is not complex, then we have an IF-THEN-ELSE combo. */
2562 else if (else_succ != NULL_EDGE
2563 && then_succ->dest == else_succ->dest
2564 && else_bb->pred->pred_next == NULL_EDGE
2565 && else_succ->succ_next == NULL_EDGE
2566 && ! (else_succ->flags & EDGE_COMPLEX)
2567 && ! (flow2_completed && tablejump_p (BB_END (else_bb), NULL, NULL)))
2568 join_bb = else_succ->dest;
2570 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2574 num_possible_if_blocks++;
2579 "\nIF-THEN%s block found, pass %d, start block %d "
2580 "[insn %d], then %d [%d]",
2581 (else_bb) ? "-ELSE" : "",
2584 BB_HEAD (test_bb) ? (int)INSN_UID (BB_HEAD (test_bb)) : -1,
2586 BB_HEAD (then_bb) ? (int)INSN_UID (BB_HEAD (then_bb)) : -1);
2589 fprintf (dump_file, ", else %d [%d]",
2591 BB_HEAD (else_bb) ? (int)INSN_UID (BB_HEAD (else_bb)) : -1);
2593 fprintf (dump_file, ", join %d [%d]",
2595 BB_HEAD (join_bb) ? (int)INSN_UID (BB_HEAD (join_bb)) : -1);
2597 if (ce_info->num_multiple_test_blocks > 0)
2598 fprintf (dump_file, ", %d %s block%s last test %d [%d]",
2599 ce_info->num_multiple_test_blocks,
2600 (ce_info->and_and_p) ? "&&" : "||",
2601 (ce_info->num_multiple_test_blocks == 1) ? "" : "s",
2602 ce_info->last_test_bb->index,
2603 ((BB_HEAD (ce_info->last_test_bb))
2604 ? (int)INSN_UID (BB_HEAD (ce_info->last_test_bb))
2607 fputc ('\n', dump_file);
2610 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2611 first condition for free, since we've already asserted that there's a
2612 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2613 we checked the FALLTHRU flag, those are already adjacent to the last IF
2615 /* ??? As an enhancement, move the ELSE block. Have to deal with
2616 BLOCK notes, if by no other means than aborting the merge if they
2617 exist. Sticky enough I don't want to think about it now. */
2619 if (else_bb && (next = next->next_bb) != else_bb)
2621 if ((next = next->next_bb) != join_bb && join_bb != EXIT_BLOCK_PTR)
2629 /* Do the real work. */
2630 ce_info->else_bb = else_bb;
2631 ce_info->join_bb = join_bb;
2633 return process_if_block (ce_info);
2636 /* Convert a branch over a trap, or a branch
2637 to a trap, into a conditional trap. */
2640 find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
2642 basic_block then_bb = then_edge->dest;
2643 basic_block else_bb = else_edge->dest;
2644 basic_block other_bb, trap_bb;
2645 rtx trap, jump, cond, cond_earliest, seq;
2648 /* Locate the block with the trap instruction. */
2649 /* ??? While we look for no successors, we really ought to allow
2650 EH successors. Need to fix merge_if_block for that to work. */
2651 if ((trap = block_has_only_trap (then_bb)) != NULL)
2652 trap_bb = then_bb, other_bb = else_bb;
2653 else if ((trap = block_has_only_trap (else_bb)) != NULL)
2654 trap_bb = else_bb, other_bb = then_bb;
2660 fprintf (dump_file, "\nTRAP-IF block found, start %d, trap %d\n",
2661 test_bb->index, trap_bb->index);
2664 /* If this is not a standard conditional jump, we can't parse it. */
2665 jump = BB_END (test_bb);
2666 cond = noce_get_condition (jump, &cond_earliest);
2670 /* If the conditional jump is more than just a conditional jump, then
2671 we can not do if-conversion on this block. */
2672 if (! onlyjump_p (jump))
2675 /* We must be comparing objects whose modes imply the size. */
2676 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2679 /* Reverse the comparison code, if necessary. */
2680 code = GET_CODE (cond);
2681 if (then_bb == trap_bb)
2683 code = reversed_comparison_code (cond, jump);
2684 if (code == UNKNOWN)
2688 /* Attempt to generate the conditional trap. */
2689 seq = gen_cond_trap (code, XEXP (cond, 0),
2691 TRAP_CODE (PATTERN (trap)));
2697 /* Emit the new insns before cond_earliest. */
2698 emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
2700 /* Delete the trap block if possible. */
2701 remove_edge (trap_bb == then_bb ? then_edge : else_edge);
2702 if (trap_bb->pred == NULL)
2703 delete_basic_block (trap_bb);
2705 /* If the non-trap block and the test are now adjacent, merge them.
2706 Otherwise we must insert a direct branch. */
2707 if (test_bb->next_bb == other_bb)
2709 struct ce_if_block new_ce_info;
2711 memset (&new_ce_info, '\0', sizeof (new_ce_info));
2712 new_ce_info.test_bb = test_bb;
2713 new_ce_info.then_bb = NULL;
2714 new_ce_info.else_bb = NULL;
2715 new_ce_info.join_bb = other_bb;
2716 merge_if_block (&new_ce_info);
2722 lab = JUMP_LABEL (jump);
2723 newjump = emit_jump_insn_after (gen_jump (lab), jump);
2724 LABEL_NUSES (lab) += 1;
2725 JUMP_LABEL (newjump) = lab;
2726 emit_barrier_after (newjump);
2734 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2738 block_has_only_trap (basic_block bb)
2742 /* We're not the exit block. */
2743 if (bb == EXIT_BLOCK_PTR)
2746 /* The block must have no successors. */
2750 /* The only instruction in the THEN block must be the trap. */
2751 trap = first_active_insn (bb);
2752 if (! (trap == BB_END (bb)
2753 && GET_CODE (PATTERN (trap)) == TRAP_IF
2754 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
2760 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2761 transformable, but not necessarily the other. There need be no
2764 Return TRUE if we were successful at converting the block.
2766 Cases we'd like to look at:
2769 if (test) goto over; // x not live
2777 if (! test) goto label;
2780 if (test) goto E; // x not live
2794 (3) // This one's really only interesting for targets that can do
2795 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2796 // it results in multiple branches on a cache line, which often
2797 // does not sit well with predictors.
2799 if (test1) goto E; // predicted not taken
2815 (A) Don't do (2) if the branch is predicted against the block we're
2816 eliminating. Do it anyway if we can eliminate a branch; this requires
2817 that the sole successor of the eliminated block postdominate the other
2820 (B) With CE, on (3) we can steal from both sides of the if, creating
2829 Again, this is most useful if J postdominates.
2831 (C) CE substitutes for helpful life information.
2833 (D) These heuristics need a lot of work. */
2835 /* Tests for case 1 above. */
2838 find_if_case_1 (basic_block test_bb, edge then_edge, edge else_edge)
2840 basic_block then_bb = then_edge->dest;
2841 basic_block else_bb = else_edge->dest, new_bb;
2842 edge then_succ = then_bb->succ;
2845 /* If we are partitioning hot/cold basic blocks, we don't want to
2846 mess up unconditional or indirect jumps that cross between hot
2847 and cold sections. */
2849 if (flag_reorder_blocks_and_partition
2850 && ((BB_END (then_bb)
2851 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
2852 || (BB_END (else_bb)
2853 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
2857 /* THEN has one successor. */
2858 if (!then_succ || then_succ->succ_next != NULL)
2861 /* THEN does not fall through, but is not strange either. */
2862 if (then_succ->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
2865 /* THEN has one predecessor. */
2866 if (then_bb->pred->pred_next != NULL)
2869 /* THEN must do something. */
2870 if (forwarder_block_p (then_bb))
2873 num_possible_if_blocks++;
2876 "\nIF-CASE-1 found, start %d, then %d\n",
2877 test_bb->index, then_bb->index);
2879 /* THEN is small. */
2880 if (count_bb_insns (then_bb) > BRANCH_COST)
2883 /* Registers set are dead, or are predicable. */
2884 if (! dead_or_predicable (test_bb, then_bb, else_bb,
2885 then_bb->succ->dest, 1))
2888 /* Conversion went ok, including moving the insns and fixing up the
2889 jump. Adjust the CFG to match. */
2891 bitmap_operation (test_bb->global_live_at_end,
2892 else_bb->global_live_at_start,
2893 then_bb->global_live_at_end, BITMAP_IOR);
2895 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb), else_bb);
2896 then_bb_index = then_bb->index;
2897 delete_basic_block (then_bb);
2899 /* Make rest of code believe that the newly created block is the THEN_BB
2900 block we removed. */
2903 new_bb->index = then_bb_index;
2904 BASIC_BLOCK (then_bb_index) = new_bb;
2906 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2910 num_updated_if_blocks++;
2915 /* Test for case 2 above. */
2918 find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
2920 basic_block then_bb = then_edge->dest;
2921 basic_block else_bb = else_edge->dest;
2922 edge else_succ = else_bb->succ;
2925 /* If we are partitioning hot/cold basic blocks, we don't want to
2926 mess up unconditional or indirect jumps that cross between hot
2927 and cold sections. */
2929 if (flag_reorder_blocks_and_partition
2930 && ((BB_END (then_bb)
2931 && find_reg_note (BB_END (then_bb), REG_CROSSING_JUMP, NULL_RTX))
2932 || (BB_END (else_bb)
2933 && find_reg_note (BB_END (else_bb), REG_CROSSING_JUMP,
2937 /* ELSE has one successor. */
2938 if (!else_succ || else_succ->succ_next != NULL)
2941 /* ELSE outgoing edge is not complex. */
2942 if (else_succ->flags & EDGE_COMPLEX)
2945 /* ELSE has one predecessor. */
2946 if (else_bb->pred->pred_next != NULL)
2949 /* THEN is not EXIT. */
2950 if (then_bb->index < 0)
2953 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2954 note = find_reg_note (BB_END (test_bb), REG_BR_PROB, NULL_RTX);
2955 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
2957 else if (else_succ->dest->index < 0
2958 || dominated_by_p (CDI_POST_DOMINATORS, then_bb,
2964 num_possible_if_blocks++;
2967 "\nIF-CASE-2 found, start %d, else %d\n",
2968 test_bb->index, else_bb->index);
2970 /* ELSE is small. */
2971 if (count_bb_insns (else_bb) > BRANCH_COST)
2974 /* Registers set are dead, or are predicable. */
2975 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
2978 /* Conversion went ok, including moving the insns and fixing up the
2979 jump. Adjust the CFG to match. */
2981 bitmap_operation (test_bb->global_live_at_end,
2982 then_bb->global_live_at_start,
2983 else_bb->global_live_at_end, BITMAP_IOR);
2985 delete_basic_block (else_bb);
2988 num_updated_if_blocks++;
2990 /* ??? We may now fallthru from one of THEN's successors into a join
2991 block. Rerun cleanup_cfg? Examine things manually? Wait? */
2996 /* A subroutine of dead_or_predicable called through for_each_rtx.
2997 Return 1 if a memory is found. */
3000 find_memory (rtx *px, void *data ATTRIBUTE_UNUSED)
3005 /* Used by the code above to perform the actual rtl transformations.
3006 Return TRUE if successful.
3008 TEST_BB is the block containing the conditional branch. MERGE_BB
3009 is the block containing the code to manipulate. NEW_DEST is the
3010 label TEST_BB should be branching to after the conversion.
3011 REVERSEP is true if the sense of the branch should be reversed. */
3014 dead_or_predicable (basic_block test_bb, basic_block merge_bb,
3015 basic_block other_bb, basic_block new_dest, int reversep)
3017 rtx head, end, jump, earliest = NULL_RTX, old_dest, new_label = NULL_RTX;
3019 jump = BB_END (test_bb);
3021 /* Find the extent of the real code in the merge block. */
3022 head = BB_HEAD (merge_bb);
3023 end = BB_END (merge_bb);
3025 if (GET_CODE (head) == CODE_LABEL)
3026 head = NEXT_INSN (head);
3027 if (GET_CODE (head) == NOTE)
3031 head = end = NULL_RTX;
3034 head = NEXT_INSN (head);
3037 if (GET_CODE (end) == JUMP_INSN)
3041 head = end = NULL_RTX;
3044 end = PREV_INSN (end);
3047 /* Disable handling dead code by conditional execution if the machine needs
3048 to do anything funny with the tests, etc. */
3049 #ifndef IFCVT_MODIFY_TESTS
3050 if (HAVE_conditional_execution)
3052 /* In the conditional execution case, we have things easy. We know
3053 the condition is reversible. We don't have to check life info
3054 because we're going to conditionally execute the code anyway.
3055 All that's left is making sure the insns involved can actually
3060 cond = cond_exec_get_condition (jump);
3064 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
3066 prob_val = XEXP (prob_val, 0);
3070 enum rtx_code rev = reversed_comparison_code (cond, jump);
3073 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
3076 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
3079 if (! cond_exec_process_insns ((ce_if_block_t *)0, head, end, cond,
3088 /* In the non-conditional execution case, we have to verify that there
3089 are no trapping operations, no calls, no references to memory, and
3090 that any registers modified are dead at the branch site. */
3092 rtx insn, cond, prev;
3093 regset_head merge_set_head, tmp_head, test_live_head, test_set_head;
3094 regset merge_set, tmp, test_live, test_set;
3095 struct propagate_block_info *pbi;
3098 /* Check for no calls or trapping operations. */
3099 for (insn = head; ; insn = NEXT_INSN (insn))
3101 if (GET_CODE (insn) == CALL_INSN)
3105 if (may_trap_p (PATTERN (insn)))
3108 /* ??? Even non-trapping memories such as stack frame
3109 references must be avoided. For stores, we collect
3110 no lifetime info; for reads, we'd have to assert
3111 true_dependence false against every store in the
3113 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
3120 if (! any_condjump_p (jump))
3123 /* Find the extent of the conditional. */
3124 cond = noce_get_condition (jump, &earliest);
3129 MERGE_SET = set of registers set in MERGE_BB
3130 TEST_LIVE = set of registers live at EARLIEST
3131 TEST_SET = set of registers set between EARLIEST and the
3132 end of the block. */
3134 tmp = INITIALIZE_REG_SET (tmp_head);
3135 merge_set = INITIALIZE_REG_SET (merge_set_head);
3136 test_live = INITIALIZE_REG_SET (test_live_head);
3137 test_set = INITIALIZE_REG_SET (test_set_head);
3139 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3140 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3141 since we've already asserted that MERGE_BB is small. */
3142 propagate_block (merge_bb, tmp, merge_set, merge_set, 0);
3144 /* For small register class machines, don't lengthen lifetimes of
3145 hard registers before reload. */
3146 if (SMALL_REGISTER_CLASSES && ! reload_completed)
3148 EXECUTE_IF_SET_IN_BITMAP
3151 if (i < FIRST_PSEUDO_REGISTER
3153 && ! global_regs[i])
3158 /* For TEST, we're interested in a range of insns, not a whole block.
3159 Moreover, we're interested in the insns live from OTHER_BB. */
3161 COPY_REG_SET (test_live, other_bb->global_live_at_start);
3162 pbi = init_propagate_block_info (test_bb, test_live, test_set, test_set,
3165 for (insn = jump; ; insn = prev)
3167 prev = propagate_one_insn (pbi, insn);
3168 if (insn == earliest)
3172 free_propagate_block_info (pbi);
3174 /* We can perform the transformation if
3175 MERGE_SET & (TEST_SET | TEST_LIVE)
3177 TEST_SET & merge_bb->global_live_at_start
3180 bitmap_operation (tmp, test_set, test_live, BITMAP_IOR);
3181 bitmap_operation (tmp, tmp, merge_set, BITMAP_AND);
3182 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
3184 bitmap_operation (tmp, test_set, merge_bb->global_live_at_start,
3186 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
3189 FREE_REG_SET (merge_set);
3190 FREE_REG_SET (test_live);
3191 FREE_REG_SET (test_set);
3198 /* We don't want to use normal invert_jump or redirect_jump because
3199 we don't want to delete_insn called. Also, we want to do our own
3200 change group management. */
3202 old_dest = JUMP_LABEL (jump);
3203 if (other_bb != new_dest)
3205 new_label = block_label (new_dest);
3207 ? ! invert_jump_1 (jump, new_label)
3208 : ! redirect_jump_1 (jump, new_label))
3212 if (! apply_change_group ())
3215 if (other_bb != new_dest)
3218 LABEL_NUSES (old_dest) -= 1;
3220 LABEL_NUSES (new_label) += 1;
3221 JUMP_LABEL (jump) = new_label;
3223 invert_br_probabilities (jump);
3225 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
3228 gcov_type count, probability;
3229 count = BRANCH_EDGE (test_bb)->count;
3230 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
3231 FALLTHRU_EDGE (test_bb)->count = count;
3232 probability = BRANCH_EDGE (test_bb)->probability;
3233 BRANCH_EDGE (test_bb)->probability
3234 = FALLTHRU_EDGE (test_bb)->probability;
3235 FALLTHRU_EDGE (test_bb)->probability = probability;
3236 update_br_prob_note (test_bb);
3240 /* Move the insns out of MERGE_BB to before the branch. */
3243 if (end == BB_END (merge_bb))
3244 BB_END (merge_bb) = PREV_INSN (head);
3246 if (squeeze_notes (&head, &end))
3249 reorder_insns (head, end, PREV_INSN (earliest));
3252 /* Remove the jump and edge if we can. */
3253 if (other_bb == new_dest)
3256 remove_edge (BRANCH_EDGE (test_bb));
3257 /* ??? Can't merge blocks here, as then_bb is still in use.
3258 At minimum, the merge will get done just before bb-reorder. */
3268 /* Main entry point for all if-conversion. */
3271 if_convert (int x_life_data_ok)
3276 num_possible_if_blocks = 0;
3277 num_updated_if_blocks = 0;
3278 num_true_changes = 0;
3279 life_data_ok = (x_life_data_ok != 0);
3281 if ((! targetm.cannot_modify_jumps_p ())
3282 && (!flag_reorder_blocks_and_partition || !no_new_pseudos))
3283 mark_loop_exit_edges ();
3285 /* Compute postdominators if we think we'll use them. */
3286 if (HAVE_conditional_execution || life_data_ok)
3287 calculate_dominance_info (CDI_POST_DOMINATORS);
3292 /* Go through each of the basic blocks looking for things to convert. If we
3293 have conditional execution, we make multiple passes to allow us to handle
3294 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3298 cond_exec_changed_p = FALSE;
3301 #ifdef IFCVT_MULTIPLE_DUMPS
3302 if (dump_file && pass > 1)
3303 fprintf (dump_file, "\n\n========== Pass %d ==========\n", pass);
3309 while ((new_bb = find_if_header (bb, pass)))
3313 #ifdef IFCVT_MULTIPLE_DUMPS
3314 if (dump_file && cond_exec_changed_p)
3315 print_rtl_with_bb (dump_file, get_insns ());
3318 while (cond_exec_changed_p);
3320 #ifdef IFCVT_MULTIPLE_DUMPS
3322 fprintf (dump_file, "\n\n========== no more changes\n");
3325 free_dominance_info (CDI_POST_DOMINATORS);
3330 clear_aux_for_blocks ();
3332 /* Rebuild life info for basic blocks that require it. */
3333 if (num_true_changes && life_data_ok)
3335 /* If we allocated new pseudos, we must resize the array for sched1. */
3336 if (max_regno < max_reg_num ())
3338 max_regno = max_reg_num ();
3339 allocate_reg_info (max_regno, FALSE, FALSE);
3341 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES,
3342 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
3343 | PROP_KILL_DEAD_CODE);
3346 /* Write the final stats. */
3347 if (dump_file && num_possible_if_blocks > 0)
3350 "\n%d possible IF blocks searched.\n",
3351 num_possible_if_blocks);
3353 "%d IF blocks converted.\n",
3354 num_updated_if_blocks);
3356 "%d true changes made.\n\n\n",
3360 #ifdef ENABLE_CHECKING
3361 verify_flow_info ();