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 int total_bb_rtx_cost (basic_block
);
90 static rtx
first_active_insn (basic_block
);
91 static rtx
last_active_insn (basic_block
, int);
92 static basic_block
block_fallthru (basic_block
);
93 static int cond_exec_process_insns (ce_if_block_t
*, rtx
, rtx
, rtx
, rtx
, int);
94 static rtx
cond_exec_get_condition (rtx
);
95 static int cond_exec_process_if_block (ce_if_block_t
*, int);
96 static rtx
noce_get_condition (rtx
, rtx
*);
97 static int noce_operand_ok (rtx
);
98 static int noce_process_if_block (ce_if_block_t
*);
99 static int process_if_block (ce_if_block_t
*);
100 static void merge_if_block (ce_if_block_t
*);
101 static int find_cond_trap (basic_block
, edge
, edge
);
102 static basic_block
find_if_header (basic_block
, int);
103 static int block_jumps_and_fallthru_p (basic_block
, basic_block
);
104 static int find_if_block (ce_if_block_t
*);
105 static int find_if_case_1 (basic_block
, edge
, edge
);
106 static int find_if_case_2 (basic_block
, edge
, edge
);
107 static int find_memory (rtx
*, void *);
108 static int dead_or_predicable (basic_block
, basic_block
, basic_block
,
110 static void noce_emit_move_insn (rtx
, rtx
);
111 static rtx
block_has_only_trap (basic_block
);
112 static void mark_loop_exit_edges (void);
114 /* Sets EDGE_LOOP_EXIT flag for all loop exits. */
116 mark_loop_exit_edges (void)
122 flow_loops_find (&loops
, LOOP_TREE
);
123 free_dominance_info (CDI_DOMINATORS
);
129 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
131 if (find_common_loop (bb
->loop_father
, e
->dest
->loop_father
)
133 e
->flags
|= EDGE_LOOP_EXIT
;
135 e
->flags
&= ~EDGE_LOOP_EXIT
;
140 flow_loops_free (&loops
);
143 /* Count the number of non-jump active insns in BB. */
146 count_bb_insns (basic_block bb
)
149 rtx insn
= BB_HEAD (bb
);
153 if (CALL_P (insn
) || NONJUMP_INSN_P (insn
))
156 if (insn
== BB_END (bb
))
158 insn
= NEXT_INSN (insn
);
164 /* Count the total insn_rtx_cost of non-jump active insns in BB.
165 This function returns -1, if the cost of any instruction could
169 total_bb_rtx_cost (basic_block bb
)
172 rtx insn
= BB_HEAD (bb
);
176 if (NONJUMP_INSN_P (insn
))
178 int cost
= insn_rtx_cost (PATTERN (insn
));
183 else if (CALL_P (insn
))
186 if (insn
== BB_END (bb
))
188 insn
= NEXT_INSN (insn
);
194 /* Return the first non-jump active insn in the basic block. */
197 first_active_insn (basic_block bb
)
199 rtx insn
= BB_HEAD (bb
);
203 if (insn
== BB_END (bb
))
205 insn
= NEXT_INSN (insn
);
208 while (NOTE_P (insn
))
210 if (insn
== BB_END (bb
))
212 insn
= NEXT_INSN (insn
);
221 /* Return the last non-jump active (non-jump) insn in the basic block. */
224 last_active_insn (basic_block bb
, int skip_use_p
)
226 rtx insn
= BB_END (bb
);
227 rtx head
= BB_HEAD (bb
);
232 && NONJUMP_INSN_P (insn
)
233 && GET_CODE (PATTERN (insn
)) == USE
))
237 insn
= PREV_INSN (insn
);
246 /* Return the basic block reached by falling though the basic block BB. */
249 block_fallthru (basic_block bb
)
254 e
!= NULL_EDGE
&& (e
->flags
& EDGE_FALLTHRU
) == 0;
258 return (e
) ? e
->dest
: NULL_BLOCK
;
261 /* Go through a bunch of insns, converting them to conditional
262 execution format if possible. Return TRUE if all of the non-note
263 insns were processed. */
266 cond_exec_process_insns (ce_if_block_t
*ce_info ATTRIBUTE_UNUSED
,
267 /* if block information */rtx start
,
268 /* first insn to look at */rtx end
,
269 /* last insn to look at */rtx test
,
270 /* conditional execution test */rtx prob_val
,
271 /* probability of branch taken. */int mod_ok
)
273 int must_be_last
= FALSE
;
281 for (insn
= start
; ; insn
= NEXT_INSN (insn
))
286 if (!NONJUMP_INSN_P (insn
) && !CALL_P (insn
))
289 /* Remove USE insns that get in the way. */
290 if (reload_completed
&& GET_CODE (PATTERN (insn
)) == USE
)
292 /* ??? Ug. Actually unlinking the thing is problematic,
293 given what we'd have to coordinate with our callers. */
294 SET_INSN_DELETED (insn
);
298 /* Last insn wasn't last? */
302 if (modified_in_p (test
, insn
))
309 /* Now build the conditional form of the instruction. */
310 pattern
= PATTERN (insn
);
311 xtest
= copy_rtx (test
);
313 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
315 if (GET_CODE (pattern
) == COND_EXEC
)
317 if (GET_MODE (xtest
) != GET_MODE (COND_EXEC_TEST (pattern
)))
320 xtest
= gen_rtx_AND (GET_MODE (xtest
), xtest
,
321 COND_EXEC_TEST (pattern
));
322 pattern
= COND_EXEC_CODE (pattern
);
325 pattern
= gen_rtx_COND_EXEC (VOIDmode
, xtest
, pattern
);
327 /* If the machine needs to modify the insn being conditionally executed,
328 say for example to force a constant integer operand into a temp
329 register, do so here. */
330 #ifdef IFCVT_MODIFY_INSN
331 IFCVT_MODIFY_INSN (ce_info
, pattern
, insn
);
336 validate_change (insn
, &PATTERN (insn
), pattern
, 1);
338 if (CALL_P (insn
) && prob_val
)
339 validate_change (insn
, ®_NOTES (insn
),
340 alloc_EXPR_LIST (REG_BR_PROB
, prob_val
,
341 REG_NOTES (insn
)), 1);
351 /* Return the condition for a jump. Do not do any special processing. */
354 cond_exec_get_condition (rtx jump
)
358 if (any_condjump_p (jump
))
359 test_if
= SET_SRC (pc_set (jump
));
362 cond
= XEXP (test_if
, 0);
364 /* If this branches to JUMP_LABEL when the condition is false,
365 reverse the condition. */
366 if (GET_CODE (XEXP (test_if
, 2)) == LABEL_REF
367 && XEXP (XEXP (test_if
, 2), 0) == JUMP_LABEL (jump
))
369 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
373 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
380 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
381 to conditional execution. Return TRUE if we were successful at
382 converting the block. */
385 cond_exec_process_if_block (ce_if_block_t
* ce_info
,
386 /* if block information */int do_multiple_p
)
388 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
389 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
390 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
391 rtx test_expr
; /* expression in IF_THEN_ELSE that is tested */
392 rtx then_start
; /* first insn in THEN block */
393 rtx then_end
; /* last insn + 1 in THEN block */
394 rtx else_start
= NULL_RTX
; /* first insn in ELSE block or NULL */
395 rtx else_end
= NULL_RTX
; /* last insn + 1 in ELSE block */
396 int max
; /* max # of insns to convert. */
397 int then_mod_ok
; /* whether conditional mods are ok in THEN */
398 rtx true_expr
; /* test for else block insns */
399 rtx false_expr
; /* test for then block insns */
400 rtx true_prob_val
; /* probability of else block */
401 rtx false_prob_val
; /* probability of then block */
403 enum rtx_code false_code
;
405 /* If test is comprised of && or || elements, and we've failed at handling
406 all of them together, just use the last test if it is the special case of
407 && elements without an ELSE block. */
408 if (!do_multiple_p
&& ce_info
->num_multiple_test_blocks
)
410 if (else_bb
|| ! ce_info
->and_and_p
)
413 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
414 ce_info
->num_multiple_test_blocks
= 0;
415 ce_info
->num_and_and_blocks
= 0;
416 ce_info
->num_or_or_blocks
= 0;
419 /* Find the conditional jump to the ELSE or JOIN part, and isolate
421 test_expr
= cond_exec_get_condition (BB_END (test_bb
));
425 /* If the conditional jump is more than just a conditional jump,
426 then we can not do conditional execution conversion on this block. */
427 if (! onlyjump_p (BB_END (test_bb
)))
430 /* Collect the bounds of where we're to search, skipping any labels, jumps
431 and notes at the beginning and end of the block. Then count the total
432 number of insns and see if it is small enough to convert. */
433 then_start
= first_active_insn (then_bb
);
434 then_end
= last_active_insn (then_bb
, TRUE
);
435 n_insns
= ce_info
->num_then_insns
= count_bb_insns (then_bb
);
436 max
= MAX_CONDITIONAL_EXECUTE
;
441 else_start
= first_active_insn (else_bb
);
442 else_end
= last_active_insn (else_bb
, TRUE
);
443 n_insns
+= ce_info
->num_else_insns
= count_bb_insns (else_bb
);
449 /* Map test_expr/test_jump into the appropriate MD tests to use on
450 the conditionally executed code. */
452 true_expr
= test_expr
;
454 false_code
= reversed_comparison_code (true_expr
, BB_END (test_bb
));
455 if (false_code
!= UNKNOWN
)
456 false_expr
= gen_rtx_fmt_ee (false_code
, GET_MODE (true_expr
),
457 XEXP (true_expr
, 0), XEXP (true_expr
, 1));
459 false_expr
= NULL_RTX
;
461 #ifdef IFCVT_MODIFY_TESTS
462 /* If the machine description needs to modify the tests, such as setting a
463 conditional execution register from a comparison, it can do so here. */
464 IFCVT_MODIFY_TESTS (ce_info
, true_expr
, false_expr
);
466 /* See if the conversion failed. */
467 if (!true_expr
|| !false_expr
)
471 true_prob_val
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
474 true_prob_val
= XEXP (true_prob_val
, 0);
475 false_prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (true_prob_val
));
478 false_prob_val
= NULL_RTX
;
480 /* If we have && or || tests, do them here. These tests are in the adjacent
481 blocks after the first block containing the test. */
482 if (ce_info
->num_multiple_test_blocks
> 0)
484 basic_block bb
= test_bb
;
485 basic_block last_test_bb
= ce_info
->last_test_bb
;
494 enum rtx_code f_code
;
496 bb
= block_fallthru (bb
);
497 start
= first_active_insn (bb
);
498 end
= last_active_insn (bb
, TRUE
);
500 && ! cond_exec_process_insns (ce_info
, start
, end
, false_expr
,
501 false_prob_val
, FALSE
))
504 /* If the conditional jump is more than just a conditional jump, then
505 we can not do conditional execution conversion on this block. */
506 if (! onlyjump_p (BB_END (bb
)))
509 /* Find the conditional jump and isolate the test. */
510 t
= cond_exec_get_condition (BB_END (bb
));
514 f_code
= reversed_comparison_code (t
, BB_END (bb
));
515 if (f_code
== UNKNOWN
)
518 f
= gen_rtx_fmt_ee (f_code
, GET_MODE (t
), XEXP (t
, 0), XEXP (t
, 1));
519 if (ce_info
->and_and_p
)
521 t
= gen_rtx_AND (GET_MODE (t
), true_expr
, t
);
522 f
= gen_rtx_IOR (GET_MODE (t
), false_expr
, f
);
526 t
= gen_rtx_IOR (GET_MODE (t
), true_expr
, t
);
527 f
= gen_rtx_AND (GET_MODE (t
), false_expr
, f
);
530 /* If the machine description needs to modify the tests, such as
531 setting a conditional execution register from a comparison, it can
533 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
534 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info
, bb
, t
, f
);
536 /* See if the conversion failed. */
544 while (bb
!= last_test_bb
);
547 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
548 on then THEN block. */
549 then_mod_ok
= (else_bb
== NULL_BLOCK
);
551 /* Go through the THEN and ELSE blocks converting the insns if possible
552 to conditional execution. */
556 || ! cond_exec_process_insns (ce_info
, then_start
, then_end
,
557 false_expr
, false_prob_val
,
561 if (else_bb
&& else_end
562 && ! cond_exec_process_insns (ce_info
, else_start
, else_end
,
563 true_expr
, true_prob_val
, TRUE
))
566 /* If we cannot apply the changes, fail. Do not go through the normal fail
567 processing, since apply_change_group will call cancel_changes. */
568 if (! apply_change_group ())
570 #ifdef IFCVT_MODIFY_CANCEL
571 /* Cancel any machine dependent changes. */
572 IFCVT_MODIFY_CANCEL (ce_info
);
577 #ifdef IFCVT_MODIFY_FINAL
578 /* Do any machine dependent final modifications. */
579 IFCVT_MODIFY_FINAL (ce_info
);
582 /* Conversion succeeded. */
584 fprintf (dump_file
, "%d insn%s converted to conditional execution.\n",
585 n_insns
, (n_insns
== 1) ? " was" : "s were");
587 /* Merge the blocks! */
588 merge_if_block (ce_info
);
589 cond_exec_changed_p
= TRUE
;
593 #ifdef IFCVT_MODIFY_CANCEL
594 /* Cancel any machine dependent changes. */
595 IFCVT_MODIFY_CANCEL (ce_info
);
602 /* Used by noce_process_if_block to communicate with its subroutines.
604 The subroutines know that A and B may be evaluated freely. They
605 know that X is a register. They should insert new instructions
606 before cond_earliest. */
613 rtx jump
, cond
, cond_earliest
;
614 /* True if "b" was originally evaluated unconditionally. */
615 bool b_unconditional
;
618 static rtx
noce_emit_store_flag (struct noce_if_info
*, rtx
, int, int);
619 static int noce_try_move (struct noce_if_info
*);
620 static int noce_try_store_flag (struct noce_if_info
*);
621 static int noce_try_addcc (struct noce_if_info
*);
622 static int noce_try_store_flag_constants (struct noce_if_info
*);
623 static int noce_try_store_flag_mask (struct noce_if_info
*);
624 static rtx
noce_emit_cmove (struct noce_if_info
*, rtx
, enum rtx_code
, rtx
,
626 static int noce_try_cmove (struct noce_if_info
*);
627 static int noce_try_cmove_arith (struct noce_if_info
*);
628 static rtx
noce_get_alt_condition (struct noce_if_info
*, rtx
, rtx
*);
629 static int noce_try_minmax (struct noce_if_info
*);
630 static int noce_try_abs (struct noce_if_info
*);
631 static int noce_try_sign_mask (struct noce_if_info
*);
633 /* Helper function for noce_try_store_flag*. */
636 noce_emit_store_flag (struct noce_if_info
*if_info
, rtx x
, int reversep
,
639 rtx cond
= if_info
->cond
;
643 cond_complex
= (! general_operand (XEXP (cond
, 0), VOIDmode
)
644 || ! general_operand (XEXP (cond
, 1), VOIDmode
));
646 /* If earliest == jump, or when the condition is complex, try to
647 build the store_flag insn directly. */
650 cond
= XEXP (SET_SRC (pc_set (if_info
->jump
)), 0);
653 code
= reversed_comparison_code (cond
, if_info
->jump
);
655 code
= GET_CODE (cond
);
657 if ((if_info
->cond_earliest
== if_info
->jump
|| cond_complex
)
658 && (normalize
== 0 || STORE_FLAG_VALUE
== normalize
))
662 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (x
), XEXP (cond
, 0),
664 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
667 tmp
= emit_insn (tmp
);
669 if (recog_memoized (tmp
) >= 0)
675 if_info
->cond_earliest
= if_info
->jump
;
683 /* Don't even try if the comparison operands or the mode of X are weird. */
684 if (cond_complex
|| !SCALAR_INT_MODE_P (GET_MODE (x
)))
687 return emit_store_flag (x
, code
, XEXP (cond
, 0),
688 XEXP (cond
, 1), VOIDmode
,
689 (code
== LTU
|| code
== LEU
690 || code
== GEU
|| code
== GTU
), normalize
);
693 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
694 X is the destination/target and Y is the value to copy. */
697 noce_emit_move_insn (rtx x
, rtx y
)
699 enum machine_mode outmode
, inmode
;
703 if (GET_CODE (x
) != STRICT_LOW_PART
)
705 emit_move_insn (x
, y
);
710 inner
= XEXP (outer
, 0);
711 outmode
= GET_MODE (outer
);
712 inmode
= GET_MODE (inner
);
713 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
714 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
, outmode
, y
);
717 /* Return sequence of instructions generated by if conversion. This
718 function calls end_sequence() to end the current stream, ensures
719 that are instructions are unshared, recognizable non-jump insns.
720 On failure, this function returns a NULL_RTX. */
723 end_ifcvt_sequence (struct noce_if_info
*if_info
)
726 rtx seq
= get_insns ();
728 set_used_flags (if_info
->x
);
729 set_used_flags (if_info
->cond
);
730 unshare_all_rtl_in_chain (seq
);
733 /* Make sure that all of the instructions emitted are recognizable,
734 and that we haven't introduced a new jump instruction.
735 As an exercise for the reader, build a general mechanism that
736 allows proper placement of required clobbers. */
737 for (insn
= seq
; insn
; insn
= NEXT_INSN (insn
))
739 || recog_memoized (insn
) == -1)
745 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
746 "if (a == b) x = a; else x = b" into "x = b". */
749 noce_try_move (struct noce_if_info
*if_info
)
751 rtx cond
= if_info
->cond
;
752 enum rtx_code code
= GET_CODE (cond
);
755 if (code
!= NE
&& code
!= EQ
)
758 /* This optimization isn't valid if either A or B could be a NaN
760 if (HONOR_NANS (GET_MODE (if_info
->x
))
761 || HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
)))
764 /* Check whether the operands of the comparison are A and in
766 if ((rtx_equal_p (if_info
->a
, XEXP (cond
, 0))
767 && rtx_equal_p (if_info
->b
, XEXP (cond
, 1)))
768 || (rtx_equal_p (if_info
->a
, XEXP (cond
, 1))
769 && rtx_equal_p (if_info
->b
, XEXP (cond
, 0))))
771 y
= (code
== EQ
) ? if_info
->a
: if_info
->b
;
773 /* Avoid generating the move if the source is the destination. */
774 if (! rtx_equal_p (if_info
->x
, y
))
777 noce_emit_move_insn (if_info
->x
, y
);
778 seq
= end_ifcvt_sequence (if_info
);
782 emit_insn_before_setloc (seq
, if_info
->jump
,
783 INSN_LOCATOR (if_info
->insn_a
));
790 /* Convert "if (test) x = 1; else x = 0".
792 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
793 tried in noce_try_store_flag_constants after noce_try_cmove has had
794 a go at the conversion. */
797 noce_try_store_flag (struct noce_if_info
*if_info
)
802 if (GET_CODE (if_info
->b
) == CONST_INT
803 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
804 && if_info
->a
== const0_rtx
)
806 else if (if_info
->b
== const0_rtx
807 && GET_CODE (if_info
->a
) == CONST_INT
808 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
809 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
817 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
820 if (target
!= if_info
->x
)
821 noce_emit_move_insn (if_info
->x
, target
);
823 seq
= end_ifcvt_sequence (if_info
);
827 emit_insn_before_setloc (seq
, if_info
->jump
,
828 INSN_LOCATOR (if_info
->insn_a
));
838 /* Convert "if (test) x = a; else x = b", for A and B constant. */
841 noce_try_store_flag_constants (struct noce_if_info
*if_info
)
845 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
846 int normalize
, can_reverse
;
847 enum machine_mode mode
;
850 && GET_CODE (if_info
->a
) == CONST_INT
851 && GET_CODE (if_info
->b
) == CONST_INT
)
853 mode
= GET_MODE (if_info
->x
);
854 ifalse
= INTVAL (if_info
->a
);
855 itrue
= INTVAL (if_info
->b
);
857 /* Make sure we can represent the difference between the two values. */
858 if ((itrue
- ifalse
> 0)
859 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
862 diff
= trunc_int_for_mode (itrue
- ifalse
, mode
);
864 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
868 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
870 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
871 && (STORE_FLAG_VALUE
== 1
872 || BRANCH_COST
>= 2))
874 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
875 && (STORE_FLAG_VALUE
== 1 || BRANCH_COST
>= 2))
876 normalize
= 1, reversep
= 1;
878 && (STORE_FLAG_VALUE
== -1
879 || BRANCH_COST
>= 2))
881 else if (ifalse
== -1 && can_reverse
882 && (STORE_FLAG_VALUE
== -1 || BRANCH_COST
>= 2))
883 normalize
= -1, reversep
= 1;
884 else if ((BRANCH_COST
>= 2 && STORE_FLAG_VALUE
== -1)
892 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
893 diff
= trunc_int_for_mode (-diff
, mode
);
897 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
904 /* if (test) x = 3; else x = 4;
905 => x = 3 + (test == 0); */
906 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
908 target
= expand_simple_binop (mode
,
909 (diff
== STORE_FLAG_VALUE
911 GEN_INT (ifalse
), target
, if_info
->x
, 0,
915 /* if (test) x = 8; else x = 0;
916 => x = (test != 0) << 3; */
917 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
919 target
= expand_simple_binop (mode
, ASHIFT
,
920 target
, GEN_INT (tmp
), if_info
->x
, 0,
924 /* if (test) x = -1; else x = b;
925 => x = -(test != 0) | b; */
926 else if (itrue
== -1)
928 target
= expand_simple_binop (mode
, IOR
,
929 target
, GEN_INT (ifalse
), if_info
->x
, 0,
933 /* if (test) x = a; else x = b;
934 => x = (-(test != 0) & (b - a)) + a; */
937 target
= expand_simple_binop (mode
, AND
,
938 target
, GEN_INT (diff
), if_info
->x
, 0,
941 target
= expand_simple_binop (mode
, PLUS
,
942 target
, GEN_INT (ifalse
),
943 if_info
->x
, 0, OPTAB_WIDEN
);
952 if (target
!= if_info
->x
)
953 noce_emit_move_insn (if_info
->x
, target
);
955 seq
= end_ifcvt_sequence (if_info
);
959 emit_insn_before_setloc (seq
, if_info
->jump
,
960 INSN_LOCATOR (if_info
->insn_a
));
967 /* Convert "if (test) foo++" into "foo += (test != 0)", and
968 similarly for "foo--". */
971 noce_try_addcc (struct noce_if_info
*if_info
)
974 int subtract
, normalize
;
977 && GET_CODE (if_info
->a
) == PLUS
978 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->b
)
979 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
982 rtx cond
= if_info
->cond
;
983 enum rtx_code code
= reversed_comparison_code (cond
, if_info
->jump
);
985 /* First try to use addcc pattern. */
986 if (general_operand (XEXP (cond
, 0), VOIDmode
)
987 && general_operand (XEXP (cond
, 1), VOIDmode
))
990 target
= emit_conditional_add (if_info
->x
, code
,
995 XEXP (if_info
->a
, 1),
996 GET_MODE (if_info
->x
),
997 (code
== LTU
|| code
== GEU
998 || code
== LEU
|| code
== GTU
));
1001 if (target
!= if_info
->x
)
1002 noce_emit_move_insn (if_info
->x
, target
);
1004 seq
= end_ifcvt_sequence (if_info
);
1008 emit_insn_before_setloc (seq
, if_info
->jump
,
1009 INSN_LOCATOR (if_info
->insn_a
));
1015 /* If that fails, construct conditional increment or decrement using
1017 if (BRANCH_COST
>= 2
1018 && (XEXP (if_info
->a
, 1) == const1_rtx
1019 || XEXP (if_info
->a
, 1) == constm1_rtx
))
1022 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1023 subtract
= 0, normalize
= 0;
1024 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
1025 subtract
= 1, normalize
= 0;
1027 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
1030 target
= noce_emit_store_flag (if_info
,
1031 gen_reg_rtx (GET_MODE (if_info
->x
)),
1035 target
= expand_simple_binop (GET_MODE (if_info
->x
),
1036 subtract
? MINUS
: PLUS
,
1037 if_info
->b
, target
, if_info
->x
,
1041 if (target
!= if_info
->x
)
1042 noce_emit_move_insn (if_info
->x
, target
);
1044 seq
= end_ifcvt_sequence (if_info
);
1048 emit_insn_before_setloc (seq
, if_info
->jump
,
1049 INSN_LOCATOR (if_info
->insn_a
));
1059 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1062 noce_try_store_flag_mask (struct noce_if_info
*if_info
)
1068 if (! no_new_pseudos
1069 && (BRANCH_COST
>= 2
1070 || STORE_FLAG_VALUE
== -1)
1071 && ((if_info
->a
== const0_rtx
1072 && rtx_equal_p (if_info
->b
, if_info
->x
))
1073 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
1076 && if_info
->b
== const0_rtx
1077 && rtx_equal_p (if_info
->a
, if_info
->x
))))
1080 target
= noce_emit_store_flag (if_info
,
1081 gen_reg_rtx (GET_MODE (if_info
->x
)),
1084 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
1086 target
, if_info
->x
, 0,
1091 if (target
!= if_info
->x
)
1092 noce_emit_move_insn (if_info
->x
, target
);
1094 seq
= end_ifcvt_sequence (if_info
);
1098 emit_insn_before_setloc (seq
, if_info
->jump
,
1099 INSN_LOCATOR (if_info
->insn_a
));
1109 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1112 noce_emit_cmove (struct noce_if_info
*if_info
, rtx x
, enum rtx_code code
,
1113 rtx cmp_a
, rtx cmp_b
, rtx vfalse
, rtx vtrue
)
1115 /* If earliest == jump, try to build the cmove insn directly.
1116 This is helpful when combine has created some complex condition
1117 (like for alpha's cmovlbs) that we can't hope to regenerate
1118 through the normal interface. */
1120 if (if_info
->cond_earliest
== if_info
->jump
)
1124 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1125 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1126 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1129 tmp
= emit_insn (tmp
);
1131 if (recog_memoized (tmp
) >= 0)
1143 /* Don't even try if the comparison operands are weird. */
1144 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1145 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1148 #if HAVE_conditional_move
1149 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1150 vtrue
, vfalse
, GET_MODE (x
),
1151 (code
== LTU
|| code
== GEU
1152 || code
== LEU
|| code
== GTU
));
1154 /* We'll never get here, as noce_process_if_block doesn't call the
1155 functions involved. Ifdef code, however, should be discouraged
1156 because it leads to typos in the code not selected. However,
1157 emit_conditional_move won't exist either. */
1162 /* Try only simple constants and registers here. More complex cases
1163 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1164 has had a go at it. */
1167 noce_try_cmove (struct noce_if_info
*if_info
)
1172 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1173 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1177 code
= GET_CODE (if_info
->cond
);
1178 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1179 XEXP (if_info
->cond
, 0),
1180 XEXP (if_info
->cond
, 1),
1181 if_info
->a
, if_info
->b
);
1185 if (target
!= if_info
->x
)
1186 noce_emit_move_insn (if_info
->x
, target
);
1188 seq
= end_ifcvt_sequence (if_info
);
1192 emit_insn_before_setloc (seq
, if_info
->jump
,
1193 INSN_LOCATOR (if_info
->insn_a
));
1206 /* Try more complex cases involving conditional_move. */
1209 noce_try_cmove_arith (struct noce_if_info
*if_info
)
1220 /* A conditional move from two memory sources is equivalent to a
1221 conditional on their addresses followed by a load. Don't do this
1222 early because it'll screw alias analysis. Note that we've
1223 already checked for no side effects. */
1224 if (! no_new_pseudos
&& cse_not_expected
1225 && MEM_P (a
) && MEM_P (b
)
1226 && BRANCH_COST
>= 5)
1230 x
= gen_reg_rtx (Pmode
);
1234 /* ??? We could handle this if we knew that a load from A or B could
1235 not fault. This is also true if we've already loaded
1236 from the address along the path from ENTRY. */
1237 else if (may_trap_p (a
) || may_trap_p (b
))
1240 /* if (test) x = a + b; else x = c - d;
1247 code
= GET_CODE (if_info
->cond
);
1248 insn_a
= if_info
->insn_a
;
1249 insn_b
= if_info
->insn_b
;
1251 /* Total insn_rtx_cost should be smaller than branch cost. Exit
1252 if insn_rtx_cost can't be estimated. */
1255 insn_cost
= insn_rtx_cost (PATTERN (insn_a
));
1256 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1265 insn_cost
+= insn_rtx_cost (PATTERN (insn_b
));
1266 if (insn_cost
== 0 || insn_cost
> COSTS_N_INSNS (BRANCH_COST
))
1270 /* Possibly rearrange operands to make things come out more natural. */
1271 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1274 if (rtx_equal_p (b
, x
))
1276 else if (general_operand (b
, GET_MODE (b
)))
1281 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1282 tmp
= a
, a
= b
, b
= tmp
;
1283 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1289 /* If either operand is complex, load it into a register first.
1290 The best way to do this is to copy the original insn. In this
1291 way we preserve any clobbers etc that the insn may have had.
1292 This is of course not possible in the IS_MEM case. */
1293 if (! general_operand (a
, GET_MODE (a
)))
1298 goto end_seq_and_fail
;
1302 tmp
= gen_reg_rtx (GET_MODE (a
));
1303 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1306 goto end_seq_and_fail
;
1309 a
= gen_reg_rtx (GET_MODE (a
));
1310 tmp
= copy_rtx (insn_a
);
1311 set
= single_set (tmp
);
1313 tmp
= emit_insn (PATTERN (tmp
));
1315 if (recog_memoized (tmp
) < 0)
1316 goto end_seq_and_fail
;
1318 if (! general_operand (b
, GET_MODE (b
)))
1323 goto end_seq_and_fail
;
1327 tmp
= gen_reg_rtx (GET_MODE (b
));
1328 tmp
= emit_insn (gen_rtx_SET (VOIDmode
,
1333 goto end_seq_and_fail
;
1336 b
= gen_reg_rtx (GET_MODE (b
));
1337 tmp
= copy_rtx (insn_b
);
1338 set
= single_set (tmp
);
1340 tmp
= emit_insn (PATTERN (tmp
));
1342 if (recog_memoized (tmp
) < 0)
1343 goto end_seq_and_fail
;
1346 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1347 XEXP (if_info
->cond
, 1), a
, b
);
1350 goto end_seq_and_fail
;
1352 /* If we're handling a memory for above, emit the load now. */
1355 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1357 /* Copy over flags as appropriate. */
1358 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1359 MEM_VOLATILE_P (tmp
) = 1;
1360 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1361 MEM_IN_STRUCT_P (tmp
) = 1;
1362 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1363 MEM_SCALAR_P (tmp
) = 1;
1364 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1365 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1367 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1369 noce_emit_move_insn (if_info
->x
, tmp
);
1371 else if (target
!= x
)
1372 noce_emit_move_insn (x
, target
);
1374 tmp
= end_ifcvt_sequence (if_info
);
1378 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1386 /* For most cases, the simplified condition we found is the best
1387 choice, but this is not the case for the min/max/abs transforms.
1388 For these we wish to know that it is A or B in the condition. */
1391 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1394 rtx cond
, set
, insn
;
1397 /* If target is already mentioned in the known condition, return it. */
1398 if (reg_mentioned_p (target
, if_info
->cond
))
1400 *earliest
= if_info
->cond_earliest
;
1401 return if_info
->cond
;
1404 set
= pc_set (if_info
->jump
);
1405 cond
= XEXP (SET_SRC (set
), 0);
1407 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1408 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1410 /* If we're looking for a constant, try to make the conditional
1411 have that constant in it. There are two reasons why it may
1412 not have the constant we want:
1414 1. GCC may have needed to put the constant in a register, because
1415 the target can't compare directly against that constant. For
1416 this case, we look for a SET immediately before the comparison
1417 that puts a constant in that register.
1419 2. GCC may have canonicalized the conditional, for example
1420 replacing "if x < 4" with "if x <= 3". We can undo that (or
1421 make equivalent types of changes) to get the constants we need
1422 if they're off by one in the right direction. */
1424 if (GET_CODE (target
) == CONST_INT
)
1426 enum rtx_code code
= GET_CODE (if_info
->cond
);
1427 rtx op_a
= XEXP (if_info
->cond
, 0);
1428 rtx op_b
= XEXP (if_info
->cond
, 1);
1431 /* First, look to see if we put a constant in a register. */
1432 prev_insn
= PREV_INSN (if_info
->cond_earliest
);
1434 && INSN_P (prev_insn
)
1435 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1437 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1439 src
= SET_SRC (PATTERN (prev_insn
));
1440 if (GET_CODE (src
) == CONST_INT
)
1442 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1444 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1447 if (GET_CODE (op_a
) == CONST_INT
)
1452 code
= swap_condition (code
);
1457 /* Now, look to see if we can get the right constant by
1458 adjusting the conditional. */
1459 if (GET_CODE (op_b
) == CONST_INT
)
1461 HOST_WIDE_INT desired_val
= INTVAL (target
);
1462 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1467 if (actual_val
== desired_val
+ 1)
1470 op_b
= GEN_INT (desired_val
);
1474 if (actual_val
== desired_val
- 1)
1477 op_b
= GEN_INT (desired_val
);
1481 if (actual_val
== desired_val
- 1)
1484 op_b
= GEN_INT (desired_val
);
1488 if (actual_val
== desired_val
+ 1)
1491 op_b
= GEN_INT (desired_val
);
1499 /* If we made any changes, generate a new conditional that is
1500 equivalent to what we started with, but has the right
1502 if (code
!= GET_CODE (if_info
->cond
)
1503 || op_a
!= XEXP (if_info
->cond
, 0)
1504 || op_b
!= XEXP (if_info
->cond
, 1))
1506 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1507 *earliest
= if_info
->cond_earliest
;
1512 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1513 earliest
, target
, false, true);
1514 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1517 /* We almost certainly searched back to a different place.
1518 Need to re-verify correct lifetimes. */
1520 /* X may not be mentioned in the range (cond_earliest, jump]. */
1521 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1522 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1525 /* A and B may not be modified in the range [cond_earliest, jump). */
1526 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1528 && (modified_in_p (if_info
->a
, insn
)
1529 || modified_in_p (if_info
->b
, insn
)))
1535 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1538 noce_try_minmax (struct noce_if_info
*if_info
)
1540 rtx cond
, earliest
, target
, seq
;
1541 enum rtx_code code
, op
;
1544 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1548 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1549 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1550 to get the target to tell us... */
1551 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1552 || HONOR_NANS (GET_MODE (if_info
->x
)))
1555 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1559 /* Verify the condition is of the form we expect, and canonicalize
1560 the comparison code. */
1561 code
= GET_CODE (cond
);
1562 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1564 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1567 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1569 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1571 code
= swap_condition (code
);
1576 /* Determine what sort of operation this is. Note that the code is for
1577 a taken branch, so the code->operation mapping appears backwards. */
1610 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1611 if_info
->a
, if_info
->b
,
1612 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1618 if (target
!= if_info
->x
)
1619 noce_emit_move_insn (if_info
->x
, target
);
1621 seq
= end_ifcvt_sequence (if_info
);
1625 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1626 if_info
->cond
= cond
;
1627 if_info
->cond_earliest
= earliest
;
1632 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1635 noce_try_abs (struct noce_if_info
*if_info
)
1637 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1640 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1644 /* Recognize A and B as constituting an ABS or NABS. */
1647 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1649 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1651 c
= a
; a
= b
; b
= c
;
1657 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1661 /* Verify the condition is of the form we expect. */
1662 if (rtx_equal_p (XEXP (cond
, 0), b
))
1664 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1669 /* Verify that C is zero. Search backward through the block for
1670 a REG_EQUAL note if necessary. */
1673 rtx insn
, note
= NULL
;
1674 for (insn
= earliest
;
1675 insn
!= BB_HEAD (if_info
->test_bb
);
1676 insn
= PREV_INSN (insn
))
1678 && ((note
= find_reg_note (insn
, REG_EQUAL
, c
))
1679 || (note
= find_reg_note (insn
, REG_EQUIV
, c
))))
1686 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1687 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1688 c
= get_pool_constant (XEXP (c
, 0));
1690 /* Work around funny ideas get_condition has wrt canonicalization.
1691 Note that these rtx constants are known to be CONST_INT, and
1692 therefore imply integer comparisons. */
1693 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1695 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1697 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1700 /* Determine what sort of operation this is. */
1701 switch (GET_CODE (cond
))
1720 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
1722 /* ??? It's a quandary whether cmove would be better here, especially
1723 for integers. Perhaps combine will clean things up. */
1724 if (target
&& negate
)
1725 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1733 if (target
!= if_info
->x
)
1734 noce_emit_move_insn (if_info
->x
, target
);
1736 seq
= end_ifcvt_sequence (if_info
);
1740 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1741 if_info
->cond
= cond
;
1742 if_info
->cond_earliest
= earliest
;
1747 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1750 noce_try_sign_mask (struct noce_if_info
*if_info
)
1752 rtx cond
, t
, m
, c
, seq
;
1753 enum machine_mode mode
;
1759 cond
= if_info
->cond
;
1760 code
= GET_CODE (cond
);
1765 if (if_info
->a
== const0_rtx
)
1767 if ((code
== LT
&& c
== const0_rtx
)
1768 || (code
== LE
&& c
== constm1_rtx
))
1771 else if (if_info
->b
== const0_rtx
)
1773 if ((code
== GE
&& c
== const0_rtx
)
1774 || (code
== GT
&& c
== constm1_rtx
))
1778 if (! t
|| side_effects_p (t
))
1781 /* We currently don't handle different modes. */
1782 mode
= GET_MODE (t
);
1783 if (GET_MODE (m
) != mode
)
1786 /* This is only profitable if T is cheap, or T is unconditionally
1787 executed/evaluated in the original insn sequence. */
1788 if (rtx_cost (t
, SET
) >= COSTS_N_INSNS (2)
1789 && (!if_info
->b_unconditional
1790 || t
!= if_info
->b
))
1794 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1795 "(signed) m >> 31" directly. This benefits targets with specialized
1796 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1797 m
= emit_store_flag (gen_reg_rtx (mode
), LT
, m
, const0_rtx
, mode
, 0, -1);
1798 t
= m
? expand_binop (mode
, and_optab
, m
, t
, NULL_RTX
, 0, OPTAB_DIRECT
)
1807 noce_emit_move_insn (if_info
->x
, t
);
1809 seq
= end_ifcvt_sequence (if_info
);
1813 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1818 /* Similar to get_condition, only the resulting condition must be
1819 valid at JUMP, instead of at EARLIEST. */
1822 noce_get_condition (rtx jump
, rtx
*earliest
)
1827 if (! any_condjump_p (jump
))
1830 set
= pc_set (jump
);
1832 /* If this branches to JUMP_LABEL when the condition is false,
1833 reverse the condition. */
1834 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1835 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
1837 /* If the condition variable is a register and is MODE_INT, accept it. */
1839 cond
= XEXP (SET_SRC (set
), 0);
1840 tmp
= XEXP (cond
, 0);
1841 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
1846 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
1847 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
1851 /* Otherwise, fall back on canonicalize_condition to do the dirty
1852 work of manipulating MODE_CC values and COMPARE rtx codes. */
1853 return canonicalize_condition (jump
, cond
, reverse
, earliest
,
1854 NULL_RTX
, false, true);
1857 /* Return true if OP is ok for if-then-else processing. */
1860 noce_operand_ok (rtx op
)
1862 /* We special-case memories, so handle any of them with
1863 no address side effects. */
1865 return ! side_effects_p (XEXP (op
, 0));
1867 if (side_effects_p (op
))
1870 return ! may_trap_p (op
);
1873 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1874 without using conditional execution. Return TRUE if we were
1875 successful at converting the block. */
1878 noce_process_if_block (struct ce_if_block
* ce_info
)
1880 basic_block test_bb
= ce_info
->test_bb
; /* test block */
1881 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1882 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1883 struct noce_if_info if_info
;
1886 rtx orig_x
, x
, a
, b
;
1889 /* We're looking for patterns of the form
1891 (1) if (...) x = a; else x = b;
1892 (2) x = b; if (...) x = a;
1893 (3) if (...) x = a; // as if with an initial x = x.
1895 The later patterns require jumps to be more expensive.
1897 ??? For future expansion, look for multiple X in such patterns. */
1899 /* If test is comprised of && or || elements, don't handle it unless it is
1900 the special case of && elements without an ELSE block. */
1901 if (ce_info
->num_multiple_test_blocks
)
1903 if (else_bb
|| ! ce_info
->and_and_p
)
1906 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
1907 ce_info
->num_multiple_test_blocks
= 0;
1908 ce_info
->num_and_and_blocks
= 0;
1909 ce_info
->num_or_or_blocks
= 0;
1912 /* If this is not a standard conditional jump, we can't parse it. */
1913 jump
= BB_END (test_bb
);
1914 cond
= noce_get_condition (jump
, &if_info
.cond_earliest
);
1918 /* If the conditional jump is more than just a conditional
1919 jump, then we can not do if-conversion on this block. */
1920 if (! onlyjump_p (jump
))
1923 /* We must be comparing objects whose modes imply the size. */
1924 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
1927 /* Look for one of the potential sets. */
1928 insn_a
= first_active_insn (then_bb
);
1930 || insn_a
!= last_active_insn (then_bb
, FALSE
)
1931 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
1934 x
= SET_DEST (set_a
);
1935 a
= SET_SRC (set_a
);
1937 /* Look for the other potential set. Make sure we've got equivalent
1939 /* ??? This is overconservative. Storing to two different mems is
1940 as easy as conditionally computing the address. Storing to a
1941 single mem merely requires a scratch memory to use as one of the
1942 destination addresses; often the memory immediately below the
1943 stack pointer is available for this. */
1947 insn_b
= first_active_insn (else_bb
);
1949 || insn_b
!= last_active_insn (else_bb
, FALSE
)
1950 || (set_b
= single_set (insn_b
)) == NULL_RTX
1951 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
1956 insn_b
= prev_nonnote_insn (if_info
.cond_earliest
);
1957 /* We're going to be moving the evaluation of B down from above
1958 COND_EARLIEST to JUMP. Make sure the relevant data is still
1961 || !NONJUMP_INSN_P (insn_b
)
1962 || (set_b
= single_set (insn_b
)) == NULL_RTX
1963 || ! rtx_equal_p (x
, SET_DEST (set_b
))
1964 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
1965 || modified_between_p (SET_SRC (set_b
),
1966 PREV_INSN (if_info
.cond_earliest
), jump
)
1967 /* Likewise with X. In particular this can happen when
1968 noce_get_condition looks farther back in the instruction
1969 stream than one might expect. */
1970 || reg_overlap_mentioned_p (x
, cond
)
1971 || reg_overlap_mentioned_p (x
, a
)
1972 || modified_between_p (x
, PREV_INSN (if_info
.cond_earliest
), jump
))
1973 insn_b
= set_b
= NULL_RTX
;
1976 /* If x has side effects then only the if-then-else form is safe to
1977 convert. But even in that case we would need to restore any notes
1978 (such as REG_INC) at then end. That can be tricky if
1979 noce_emit_move_insn expands to more than one insn, so disable the
1980 optimization entirely for now if there are side effects. */
1981 if (side_effects_p (x
))
1984 b
= (set_b
? SET_SRC (set_b
) : x
);
1986 /* Only operate on register destinations, and even then avoid extending
1987 the lifetime of hard registers on small register class machines. */
1990 || (SMALL_REGISTER_CLASSES
1991 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
1993 if (no_new_pseudos
|| GET_MODE (x
) == BLKmode
)
1995 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
1996 ? XEXP (x
, 0) : x
));
1999 /* Don't operate on sources that may trap or are volatile. */
2000 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
2003 /* Set up the info block for our subroutines. */
2004 if_info
.test_bb
= test_bb
;
2005 if_info
.cond
= cond
;
2006 if_info
.jump
= jump
;
2007 if_info
.insn_a
= insn_a
;
2008 if_info
.insn_b
= insn_b
;
2012 if_info
.b_unconditional
= else_bb
== 0;
2014 /* Try optimizations in some approximation of a useful order. */
2015 /* ??? Should first look to see if X is live incoming at all. If it
2016 isn't, we don't need anything but an unconditional set. */
2018 /* Look and see if A and B are really the same. Avoid creating silly
2019 cmove constructs that no one will fix up later. */
2020 if (rtx_equal_p (a
, b
))
2022 /* If we have an INSN_B, we don't have to create any new rtl. Just
2023 move the instruction that we already have. If we don't have an
2024 INSN_B, that means that A == X, and we've got a noop move. In
2025 that case don't do anything and let the code below delete INSN_A. */
2026 if (insn_b
&& else_bb
)
2030 if (else_bb
&& insn_b
== BB_END (else_bb
))
2031 BB_END (else_bb
) = PREV_INSN (insn_b
);
2032 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
2034 /* If there was a REG_EQUAL note, delete it since it may have been
2035 true due to this insn being after a jump. */
2036 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
2037 remove_note (insn_b
, note
);
2041 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2042 x must be executed twice. */
2043 else if (insn_b
&& side_effects_p (orig_x
))
2050 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2051 for most optimizations if writing to x may trap, i.e. it's a memory
2052 other than a static var or a stack slot. */
2055 && ! MEM_NOTRAP_P (orig_x
)
2056 && rtx_addr_can_trap_p (XEXP (orig_x
, 0)))
2058 if (HAVE_conditional_move
)
2060 if (noce_try_cmove (&if_info
))
2062 if (! HAVE_conditional_execution
2063 && noce_try_cmove_arith (&if_info
))
2069 if (noce_try_move (&if_info
))
2071 if (noce_try_store_flag (&if_info
))
2073 if (noce_try_minmax (&if_info
))
2075 if (noce_try_abs (&if_info
))
2077 if (HAVE_conditional_move
2078 && noce_try_cmove (&if_info
))
2080 if (! HAVE_conditional_execution
)
2082 if (noce_try_store_flag_constants (&if_info
))
2084 if (noce_try_addcc (&if_info
))
2086 if (noce_try_store_flag_mask (&if_info
))
2088 if (HAVE_conditional_move
2089 && noce_try_cmove_arith (&if_info
))
2091 if (noce_try_sign_mask (&if_info
))
2098 /* The original sets may now be killed. */
2099 delete_insn (insn_a
);
2101 /* Several special cases here: First, we may have reused insn_b above,
2102 in which case insn_b is now NULL. Second, we want to delete insn_b
2103 if it came from the ELSE block, because follows the now correct
2104 write that appears in the TEST block. However, if we got insn_b from
2105 the TEST block, it may in fact be loading data needed for the comparison.
2106 We'll let life_analysis remove the insn if it's really dead. */
2107 if (insn_b
&& else_bb
)
2108 delete_insn (insn_b
);
2110 /* The new insns will have been inserted immediately before the jump. We
2111 should be able to remove the jump with impunity, but the condition itself
2112 may have been modified by gcse to be shared across basic blocks. */
2115 /* If we used a temporary, fix it up now. */
2119 noce_emit_move_insn (orig_x
, x
);
2120 insn_b
= get_insns ();
2121 set_used_flags (orig_x
);
2122 unshare_all_rtl_in_chain (insn_b
);
2125 emit_insn_after_setloc (insn_b
, BB_END (test_bb
), INSN_LOCATOR (insn_a
));
2128 /* Merge the blocks! */
2129 merge_if_block (ce_info
);
2134 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2135 straight line code. Return true if successful. */
2138 process_if_block (struct ce_if_block
* ce_info
)
2140 if (! reload_completed
2141 && noce_process_if_block (ce_info
))
2144 if (HAVE_conditional_execution
&& reload_completed
)
2146 /* If we have && and || tests, try to first handle combining the && and
2147 || tests into the conditional code, and if that fails, go back and
2148 handle it without the && and ||, which at present handles the && case
2149 if there was no ELSE block. */
2150 if (cond_exec_process_if_block (ce_info
, TRUE
))
2153 if (ce_info
->num_multiple_test_blocks
)
2157 if (cond_exec_process_if_block (ce_info
, FALSE
))
2165 /* Merge the blocks and mark for local life update. */
2168 merge_if_block (struct ce_if_block
* ce_info
)
2170 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
2171 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
2172 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
2173 basic_block join_bb
= ce_info
->join_bb
; /* join block */
2174 basic_block combo_bb
;
2176 /* All block merging is done into the lower block numbers. */
2180 /* Merge any basic blocks to handle && and || subtests. Each of
2181 the blocks are on the fallthru path from the predecessor block. */
2182 if (ce_info
->num_multiple_test_blocks
> 0)
2184 basic_block bb
= test_bb
;
2185 basic_block last_test_bb
= ce_info
->last_test_bb
;
2186 basic_block fallthru
= block_fallthru (bb
);
2191 fallthru
= block_fallthru (bb
);
2192 merge_blocks (combo_bb
, bb
);
2195 while (bb
!= last_test_bb
);
2198 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2199 label, but it might if there were || tests. That label's count should be
2200 zero, and it normally should be removed. */
2204 if (combo_bb
->global_live_at_end
)
2205 COPY_REG_SET (combo_bb
->global_live_at_end
,
2206 then_bb
->global_live_at_end
);
2207 merge_blocks (combo_bb
, then_bb
);
2211 /* The ELSE block, if it existed, had a label. That label count
2212 will almost always be zero, but odd things can happen when labels
2213 get their addresses taken. */
2216 merge_blocks (combo_bb
, else_bb
);
2220 /* If there was no join block reported, that means it was not adjacent
2221 to the others, and so we cannot merge them. */
2225 rtx last
= BB_END (combo_bb
);
2227 /* The outgoing edge for the current COMBO block should already
2228 be correct. Verify this. */
2229 if (combo_bb
->succ
== NULL_EDGE
)
2231 if (find_reg_note (last
, REG_NORETURN
, NULL
))
2233 else if (NONJUMP_INSN_P (last
)
2234 && GET_CODE (PATTERN (last
)) == TRAP_IF
2235 && TRAP_CONDITION (PATTERN (last
)) == const_true_rtx
)
2241 /* There should still be something at the end of the THEN or ELSE
2242 blocks taking us to our final destination. */
2243 else if (JUMP_P (last
))
2245 else if (combo_bb
->succ
->dest
== EXIT_BLOCK_PTR
2247 && SIBLING_CALL_P (last
))
2249 else if ((combo_bb
->succ
->flags
& EDGE_EH
)
2250 && can_throw_internal (last
))
2256 /* The JOIN block may have had quite a number of other predecessors too.
2257 Since we've already merged the TEST, THEN and ELSE blocks, we should
2258 have only one remaining edge from our if-then-else diamond. If there
2259 is more than one remaining edge, it must come from elsewhere. There
2260 may be zero incoming edges if the THEN block didn't actually join
2261 back up (as with a call to abort). */
2262 else if ((join_bb
->pred
== NULL
2263 || join_bb
->pred
->pred_next
== NULL
)
2264 && join_bb
!= EXIT_BLOCK_PTR
)
2266 /* We can merge the JOIN. */
2267 if (combo_bb
->global_live_at_end
)
2268 COPY_REG_SET (combo_bb
->global_live_at_end
,
2269 join_bb
->global_live_at_end
);
2271 merge_blocks (combo_bb
, join_bb
);
2276 /* We cannot merge the JOIN. */
2278 /* The outgoing edge for the current COMBO block should already
2279 be correct. Verify this. */
2280 if (combo_bb
->succ
->succ_next
!= NULL_EDGE
2281 || combo_bb
->succ
->dest
!= join_bb
)
2284 /* Remove the jump and cruft from the end of the COMBO block. */
2285 if (join_bb
!= EXIT_BLOCK_PTR
)
2286 tidy_fallthru_edge (combo_bb
->succ
);
2289 num_updated_if_blocks
++;
2292 /* Find a block ending in a simple IF condition and try to transform it
2293 in some way. When converting a multi-block condition, put the new code
2294 in the first such block and delete the rest. Return a pointer to this
2295 first block if some transformation was done. Return NULL otherwise. */
2298 find_if_header (basic_block test_bb
, int pass
)
2300 ce_if_block_t ce_info
;
2304 /* The kind of block we're looking for has exactly two successors. */
2305 if ((then_edge
= test_bb
->succ
) == NULL_EDGE
2306 || (else_edge
= then_edge
->succ_next
) == NULL_EDGE
2307 || else_edge
->succ_next
!= NULL_EDGE
)
2310 /* Neither edge should be abnormal. */
2311 if ((then_edge
->flags
& EDGE_COMPLEX
)
2312 || (else_edge
->flags
& EDGE_COMPLEX
))
2315 /* Nor exit the loop. */
2316 if ((then_edge
->flags
& EDGE_LOOP_EXIT
)
2317 || (else_edge
->flags
& EDGE_LOOP_EXIT
))
2320 /* The THEN edge is canonically the one that falls through. */
2321 if (then_edge
->flags
& EDGE_FALLTHRU
)
2323 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2326 else_edge
= then_edge
;
2330 /* Otherwise this must be a multiway branch of some sort. */
2333 memset (&ce_info
, '\0', sizeof (ce_info
));
2334 ce_info
.test_bb
= test_bb
;
2335 ce_info
.then_bb
= then_edge
->dest
;
2336 ce_info
.else_bb
= else_edge
->dest
;
2337 ce_info
.pass
= pass
;
2339 #ifdef IFCVT_INIT_EXTRA_FIELDS
2340 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2343 if (find_if_block (&ce_info
))
2346 if (HAVE_trap
&& HAVE_conditional_trap
2347 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2350 if (dom_computed
[CDI_POST_DOMINATORS
] >= DOM_NO_FAST_QUERY
2351 && (! HAVE_conditional_execution
|| reload_completed
))
2353 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2355 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2363 fprintf (dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2364 return ce_info
.test_bb
;
2367 /* Return true if a block has two edges, one of which falls through to the next
2368 block, and the other jumps to a specific block, so that we can tell if the
2369 block is part of an && test or an || test. Returns either -1 or the number
2370 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2373 block_jumps_and_fallthru_p (basic_block cur_bb
, basic_block target_bb
)
2376 int fallthru_p
= FALSE
;
2382 if (!cur_bb
|| !target_bb
)
2385 /* If no edges, obviously it doesn't jump or fallthru. */
2386 if (cur_bb
->succ
== NULL_EDGE
)
2389 for (cur_edge
= cur_bb
->succ
;
2390 cur_edge
!= NULL_EDGE
;
2391 cur_edge
= cur_edge
->succ_next
)
2393 if (cur_edge
->flags
& EDGE_COMPLEX
)
2394 /* Anything complex isn't what we want. */
2397 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2400 else if (cur_edge
->dest
== target_bb
)
2407 if ((jump_p
& fallthru_p
) == 0)
2410 /* Don't allow calls in the block, since this is used to group && and ||
2411 together for conditional execution support. ??? we should support
2412 conditional execution support across calls for IA-64 some day, but
2413 for now it makes the code simpler. */
2414 end
= BB_END (cur_bb
);
2415 insn
= BB_HEAD (cur_bb
);
2417 while (insn
!= NULL_RTX
)
2424 && GET_CODE (PATTERN (insn
)) != USE
2425 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
2431 insn
= NEXT_INSN (insn
);
2437 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2438 block. If so, we'll try to convert the insns to not require the branch.
2439 Return TRUE if we were successful at converting the block. */
2442 find_if_block (struct ce_if_block
* ce_info
)
2444 basic_block test_bb
= ce_info
->test_bb
;
2445 basic_block then_bb
= ce_info
->then_bb
;
2446 basic_block else_bb
= ce_info
->else_bb
;
2447 basic_block join_bb
= NULL_BLOCK
;
2448 edge then_succ
= then_bb
->succ
;
2449 edge else_succ
= else_bb
->succ
;
2450 int then_predecessors
;
2451 int else_predecessors
;
2455 ce_info
->last_test_bb
= test_bb
;
2457 /* Discover if any fall through predecessors of the current test basic block
2458 were && tests (which jump to the else block) or || tests (which jump to
2460 if (HAVE_conditional_execution
&& reload_completed
2461 && test_bb
->pred
!= NULL_EDGE
2462 && test_bb
->pred
->pred_next
== NULL_EDGE
2463 && test_bb
->pred
->flags
== EDGE_FALLTHRU
)
2465 basic_block bb
= test_bb
->pred
->src
;
2466 basic_block target_bb
;
2467 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
2470 /* Determine if the preceding block is an && or || block. */
2471 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
2473 ce_info
->and_and_p
= TRUE
;
2474 target_bb
= else_bb
;
2476 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
2478 ce_info
->and_and_p
= FALSE
;
2479 target_bb
= then_bb
;
2482 target_bb
= NULL_BLOCK
;
2484 if (target_bb
&& n_insns
<= max_insns
)
2486 int total_insns
= 0;
2489 ce_info
->last_test_bb
= test_bb
;
2491 /* Found at least one && or || block, look for more. */
2494 ce_info
->test_bb
= test_bb
= bb
;
2495 total_insns
+= n_insns
;
2498 if (bb
->pred
== NULL_EDGE
|| bb
->pred
->pred_next
!= NULL_EDGE
)
2502 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
2504 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
2506 ce_info
->num_multiple_test_blocks
= blocks
;
2507 ce_info
->num_multiple_test_insns
= total_insns
;
2509 if (ce_info
->and_and_p
)
2510 ce_info
->num_and_and_blocks
= blocks
;
2512 ce_info
->num_or_or_blocks
= blocks
;
2516 /* Count the number of edges the THEN and ELSE blocks have. */
2517 then_predecessors
= 0;
2518 for (cur_edge
= then_bb
->pred
;
2519 cur_edge
!= NULL_EDGE
;
2520 cur_edge
= cur_edge
->pred_next
)
2522 then_predecessors
++;
2523 if (cur_edge
->flags
& EDGE_COMPLEX
)
2527 else_predecessors
= 0;
2528 for (cur_edge
= else_bb
->pred
;
2529 cur_edge
!= NULL_EDGE
;
2530 cur_edge
= cur_edge
->pred_next
)
2532 else_predecessors
++;
2533 if (cur_edge
->flags
& EDGE_COMPLEX
)
2537 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2538 other than any || blocks which jump to the THEN block. */
2539 if ((then_predecessors
- ce_info
->num_or_or_blocks
) != 1)
2542 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2543 if (then_succ
!= NULL_EDGE
2544 && (then_succ
->succ_next
!= NULL_EDGE
2545 || (then_succ
->flags
& EDGE_COMPLEX
)
2546 || (flow2_completed
&& tablejump_p (BB_END (then_bb
), NULL
, NULL
))))
2549 /* If the THEN block has no successors, conditional execution can still
2550 make a conditional call. Don't do this unless the ELSE block has
2551 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2552 Check for the last insn of the THEN block being an indirect jump, which
2553 is listed as not having any successors, but confuses the rest of the CE
2554 code processing. ??? we should fix this in the future. */
2555 if (then_succ
== NULL
)
2557 if (else_bb
->pred
->pred_next
== NULL_EDGE
)
2559 rtx last_insn
= BB_END (then_bb
);
2562 && NOTE_P (last_insn
)
2563 && last_insn
!= BB_HEAD (then_bb
))
2564 last_insn
= PREV_INSN (last_insn
);
2567 && JUMP_P (last_insn
)
2568 && ! simplejump_p (last_insn
))
2572 else_bb
= NULL_BLOCK
;
2578 /* If the THEN block's successor is the other edge out of the TEST block,
2579 then we have an IF-THEN combo without an ELSE. */
2580 else if (then_succ
->dest
== else_bb
)
2583 else_bb
= NULL_BLOCK
;
2586 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2587 has exactly one predecessor and one successor, and the outgoing edge
2588 is not complex, then we have an IF-THEN-ELSE combo. */
2589 else if (else_succ
!= NULL_EDGE
2590 && then_succ
->dest
== else_succ
->dest
2591 && else_bb
->pred
->pred_next
== NULL_EDGE
2592 && else_succ
->succ_next
== NULL_EDGE
2593 && ! (else_succ
->flags
& EDGE_COMPLEX
)
2594 && ! (flow2_completed
&& tablejump_p (BB_END (else_bb
), NULL
, NULL
)))
2595 join_bb
= else_succ
->dest
;
2597 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2601 num_possible_if_blocks
++;
2606 "\nIF-THEN%s block found, pass %d, start block %d "
2607 "[insn %d], then %d [%d]",
2608 (else_bb
) ? "-ELSE" : "",
2611 BB_HEAD (test_bb
) ? (int)INSN_UID (BB_HEAD (test_bb
)) : -1,
2613 BB_HEAD (then_bb
) ? (int)INSN_UID (BB_HEAD (then_bb
)) : -1);
2616 fprintf (dump_file
, ", else %d [%d]",
2618 BB_HEAD (else_bb
) ? (int)INSN_UID (BB_HEAD (else_bb
)) : -1);
2620 fprintf (dump_file
, ", join %d [%d]",
2622 BB_HEAD (join_bb
) ? (int)INSN_UID (BB_HEAD (join_bb
)) : -1);
2624 if (ce_info
->num_multiple_test_blocks
> 0)
2625 fprintf (dump_file
, ", %d %s block%s last test %d [%d]",
2626 ce_info
->num_multiple_test_blocks
,
2627 (ce_info
->and_and_p
) ? "&&" : "||",
2628 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
2629 ce_info
->last_test_bb
->index
,
2630 ((BB_HEAD (ce_info
->last_test_bb
))
2631 ? (int)INSN_UID (BB_HEAD (ce_info
->last_test_bb
))
2634 fputc ('\n', dump_file
);
2637 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2638 first condition for free, since we've already asserted that there's a
2639 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2640 we checked the FALLTHRU flag, those are already adjacent to the last IF
2642 /* ??? As an enhancement, move the ELSE block. Have to deal with
2643 BLOCK notes, if by no other means than aborting the merge if they
2644 exist. Sticky enough I don't want to think about it now. */
2646 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
2648 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
2656 /* Do the real work. */
2657 ce_info
->else_bb
= else_bb
;
2658 ce_info
->join_bb
= join_bb
;
2660 return process_if_block (ce_info
);
2663 /* Convert a branch over a trap, or a branch
2664 to a trap, into a conditional trap. */
2667 find_cond_trap (basic_block test_bb
, edge then_edge
, edge else_edge
)
2669 basic_block then_bb
= then_edge
->dest
;
2670 basic_block else_bb
= else_edge
->dest
;
2671 basic_block other_bb
, trap_bb
;
2672 rtx trap
, jump
, cond
, cond_earliest
, seq
;
2675 /* Locate the block with the trap instruction. */
2676 /* ??? While we look for no successors, we really ought to allow
2677 EH successors. Need to fix merge_if_block for that to work. */
2678 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
2679 trap_bb
= then_bb
, other_bb
= else_bb
;
2680 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
2681 trap_bb
= else_bb
, other_bb
= then_bb
;
2687 fprintf (dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
2688 test_bb
->index
, trap_bb
->index
);
2691 /* If this is not a standard conditional jump, we can't parse it. */
2692 jump
= BB_END (test_bb
);
2693 cond
= noce_get_condition (jump
, &cond_earliest
);
2697 /* If the conditional jump is more than just a conditional jump, then
2698 we can not do if-conversion on this block. */
2699 if (! onlyjump_p (jump
))
2702 /* We must be comparing objects whose modes imply the size. */
2703 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2706 /* Reverse the comparison code, if necessary. */
2707 code
= GET_CODE (cond
);
2708 if (then_bb
== trap_bb
)
2710 code
= reversed_comparison_code (cond
, jump
);
2711 if (code
== UNKNOWN
)
2715 /* Attempt to generate the conditional trap. */
2716 seq
= gen_cond_trap (code
, XEXP (cond
, 0),
2718 TRAP_CODE (PATTERN (trap
)));
2724 /* Emit the new insns before cond_earliest. */
2725 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATOR (trap
));
2727 /* Delete the trap block if possible. */
2728 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
2729 if (trap_bb
->pred
== NULL
)
2730 delete_basic_block (trap_bb
);
2732 /* If the non-trap block and the test are now adjacent, merge them.
2733 Otherwise we must insert a direct branch. */
2734 if (test_bb
->next_bb
== other_bb
)
2736 struct ce_if_block new_ce_info
;
2738 memset (&new_ce_info
, '\0', sizeof (new_ce_info
));
2739 new_ce_info
.test_bb
= test_bb
;
2740 new_ce_info
.then_bb
= NULL
;
2741 new_ce_info
.else_bb
= NULL
;
2742 new_ce_info
.join_bb
= other_bb
;
2743 merge_if_block (&new_ce_info
);
2749 lab
= JUMP_LABEL (jump
);
2750 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
2751 LABEL_NUSES (lab
) += 1;
2752 JUMP_LABEL (newjump
) = lab
;
2753 emit_barrier_after (newjump
);
2761 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2765 block_has_only_trap (basic_block bb
)
2769 /* We're not the exit block. */
2770 if (bb
== EXIT_BLOCK_PTR
)
2773 /* The block must have no successors. */
2777 /* The only instruction in the THEN block must be the trap. */
2778 trap
= first_active_insn (bb
);
2779 if (! (trap
== BB_END (bb
)
2780 && GET_CODE (PATTERN (trap
)) == TRAP_IF
2781 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
2787 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2788 transformable, but not necessarily the other. There need be no
2791 Return TRUE if we were successful at converting the block.
2793 Cases we'd like to look at:
2796 if (test) goto over; // x not live
2804 if (! test) goto label;
2807 if (test) goto E; // x not live
2821 (3) // This one's really only interesting for targets that can do
2822 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2823 // it results in multiple branches on a cache line, which often
2824 // does not sit well with predictors.
2826 if (test1) goto E; // predicted not taken
2842 (A) Don't do (2) if the branch is predicted against the block we're
2843 eliminating. Do it anyway if we can eliminate a branch; this requires
2844 that the sole successor of the eliminated block postdominate the other
2847 (B) With CE, on (3) we can steal from both sides of the if, creating
2856 Again, this is most useful if J postdominates.
2858 (C) CE substitutes for helpful life information.
2860 (D) These heuristics need a lot of work. */
2862 /* Tests for case 1 above. */
2865 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2867 basic_block then_bb
= then_edge
->dest
;
2868 basic_block else_bb
= else_edge
->dest
, new_bb
;
2869 edge then_succ
= then_bb
->succ
;
2870 int then_bb_index
, bb_cost
;
2872 /* If we are partitioning hot/cold basic blocks, we don't want to
2873 mess up unconditional or indirect jumps that cross between hot
2876 Basic block partitioning may result in some jumps that appear to
2877 be optimizable (or blocks that appear to be mergeable), but which really
2878 must be left untouched (they are required to make it safely across
2879 partition boundaries). See the comments at the top of
2880 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2882 if (flag_reorder_blocks_and_partition
2883 && ((BB_END (then_bb
)
2884 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2885 || (BB_END (else_bb
)
2886 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2890 /* THEN has one successor. */
2891 if (!then_succ
|| then_succ
->succ_next
!= NULL
)
2894 /* THEN does not fall through, but is not strange either. */
2895 if (then_succ
->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
2898 /* THEN has one predecessor. */
2899 if (then_bb
->pred
->pred_next
!= NULL
)
2902 /* THEN must do something. */
2903 if (forwarder_block_p (then_bb
))
2906 num_possible_if_blocks
++;
2909 "\nIF-CASE-1 found, start %d, then %d\n",
2910 test_bb
->index
, then_bb
->index
);
2912 /* THEN is small. */
2913 bb_cost
= total_bb_rtx_cost (then_bb
);
2914 if (bb_cost
< 0 || bb_cost
>= COSTS_N_INSNS (BRANCH_COST
))
2917 /* Registers set are dead, or are predicable. */
2918 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
2919 then_bb
->succ
->dest
, 1))
2922 /* Conversion went ok, including moving the insns and fixing up the
2923 jump. Adjust the CFG to match. */
2925 bitmap_operation (test_bb
->global_live_at_end
,
2926 else_bb
->global_live_at_start
,
2927 then_bb
->global_live_at_end
, BITMAP_IOR
);
2929 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
), else_bb
);
2930 then_bb_index
= then_bb
->index
;
2931 delete_basic_block (then_bb
);
2933 /* Make rest of code believe that the newly created block is the THEN_BB
2934 block we removed. */
2937 new_bb
->index
= then_bb_index
;
2938 BASIC_BLOCK (then_bb_index
) = new_bb
;
2939 /* Since the fallthru edge was redirected from test_bb to new_bb,
2940 we need to ensure that new_bb is in the same partition as
2941 test bb (you can not fall through across section boundaries). */
2942 BB_COPY_PARTITION (new_bb
, test_bb
);
2944 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2948 num_updated_if_blocks
++;
2953 /* Test for case 2 above. */
2956 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2958 basic_block then_bb
= then_edge
->dest
;
2959 basic_block else_bb
= else_edge
->dest
;
2960 edge else_succ
= else_bb
->succ
;
2964 /* If we are partitioning hot/cold basic blocks, we don't want to
2965 mess up unconditional or indirect jumps that cross between hot
2968 Basic block partitioning may result in some jumps that appear to
2969 be optimizable (or blocks that appear to be mergeable), but which really
2970 must be left untouched (they are required to make it safely across
2971 partition boundaries). See the comments at the top of
2972 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2974 if (flag_reorder_blocks_and_partition
2975 && ((BB_END (then_bb
)
2976 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2977 || (BB_END (else_bb
)
2978 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2982 /* ELSE has one successor. */
2983 if (!else_succ
|| else_succ
->succ_next
!= NULL
)
2986 /* ELSE outgoing edge is not complex. */
2987 if (else_succ
->flags
& EDGE_COMPLEX
)
2990 /* ELSE has one predecessor. */
2991 if (else_bb
->pred
->pred_next
!= NULL
)
2994 /* THEN is not EXIT. */
2995 if (then_bb
->index
< 0)
2998 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2999 note
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
3000 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
3002 else if (else_succ
->dest
->index
< 0
3003 || dominated_by_p (CDI_POST_DOMINATORS
, then_bb
,
3009 num_possible_if_blocks
++;
3012 "\nIF-CASE-2 found, start %d, else %d\n",
3013 test_bb
->index
, else_bb
->index
);
3015 /* ELSE is small. */
3016 bb_cost
= total_bb_rtx_cost (else_bb
);
3017 if (bb_cost
< 0 || bb_cost
>= COSTS_N_INSNS (BRANCH_COST
))
3020 /* Registers set are dead, or are predicable. */
3021 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
3024 /* Conversion went ok, including moving the insns and fixing up the
3025 jump. Adjust the CFG to match. */
3027 bitmap_operation (test_bb
->global_live_at_end
,
3028 then_bb
->global_live_at_start
,
3029 else_bb
->global_live_at_end
, BITMAP_IOR
);
3031 delete_basic_block (else_bb
);
3034 num_updated_if_blocks
++;
3036 /* ??? We may now fallthru from one of THEN's successors into a join
3037 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3042 /* A subroutine of dead_or_predicable called through for_each_rtx.
3043 Return 1 if a memory is found. */
3046 find_memory (rtx
*px
, void *data ATTRIBUTE_UNUSED
)
3051 /* Used by the code above to perform the actual rtl transformations.
3052 Return TRUE if successful.
3054 TEST_BB is the block containing the conditional branch. MERGE_BB
3055 is the block containing the code to manipulate. NEW_DEST is the
3056 label TEST_BB should be branching to after the conversion.
3057 REVERSEP is true if the sense of the branch should be reversed. */
3060 dead_or_predicable (basic_block test_bb
, basic_block merge_bb
,
3061 basic_block other_bb
, basic_block new_dest
, int reversep
)
3063 rtx head
, end
, jump
, earliest
= NULL_RTX
, old_dest
, new_label
= NULL_RTX
;
3065 jump
= BB_END (test_bb
);
3067 /* Find the extent of the real code in the merge block. */
3068 head
= BB_HEAD (merge_bb
);
3069 end
= BB_END (merge_bb
);
3072 head
= NEXT_INSN (head
);
3077 head
= end
= NULL_RTX
;
3080 head
= NEXT_INSN (head
);
3087 head
= end
= NULL_RTX
;
3090 end
= PREV_INSN (end
);
3093 /* Disable handling dead code by conditional execution if the machine needs
3094 to do anything funny with the tests, etc. */
3095 #ifndef IFCVT_MODIFY_TESTS
3096 if (HAVE_conditional_execution
)
3098 /* In the conditional execution case, we have things easy. We know
3099 the condition is reversible. We don't have to check life info
3100 because we're going to conditionally execute the code anyway.
3101 All that's left is making sure the insns involved can actually
3106 cond
= cond_exec_get_condition (jump
);
3110 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
3112 prob_val
= XEXP (prob_val
, 0);
3116 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
3119 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
3122 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
3125 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
3134 /* In the non-conditional execution case, we have to verify that there
3135 are no trapping operations, no calls, no references to memory, and
3136 that any registers modified are dead at the branch site. */
3138 rtx insn
, cond
, prev
;
3139 regset_head merge_set_head
, tmp_head
, test_live_head
, test_set_head
;
3140 regset merge_set
, tmp
, test_live
, test_set
;
3141 struct propagate_block_info
*pbi
;
3145 /* Check for no calls or trapping operations. */
3146 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
3152 if (may_trap_p (PATTERN (insn
)))
3155 /* ??? Even non-trapping memories such as stack frame
3156 references must be avoided. For stores, we collect
3157 no lifetime info; for reads, we'd have to assert
3158 true_dependence false against every store in the
3160 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
3167 if (! any_condjump_p (jump
))
3170 /* Find the extent of the conditional. */
3171 cond
= noce_get_condition (jump
, &earliest
);
3176 MERGE_SET = set of registers set in MERGE_BB
3177 TEST_LIVE = set of registers live at EARLIEST
3178 TEST_SET = set of registers set between EARLIEST and the
3179 end of the block. */
3181 tmp
= INITIALIZE_REG_SET (tmp_head
);
3182 merge_set
= INITIALIZE_REG_SET (merge_set_head
);
3183 test_live
= INITIALIZE_REG_SET (test_live_head
);
3184 test_set
= INITIALIZE_REG_SET (test_set_head
);
3186 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3187 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3188 since we've already asserted that MERGE_BB is small. */
3189 propagate_block (merge_bb
, tmp
, merge_set
, merge_set
, 0);
3191 /* For small register class machines, don't lengthen lifetimes of
3192 hard registers before reload. */
3193 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
3195 EXECUTE_IF_SET_IN_BITMAP (merge_set
, 0, i
, bi
)
3197 if (i
< FIRST_PSEUDO_REGISTER
3199 && ! global_regs
[i
])
3204 /* For TEST, we're interested in a range of insns, not a whole block.
3205 Moreover, we're interested in the insns live from OTHER_BB. */
3207 COPY_REG_SET (test_live
, other_bb
->global_live_at_start
);
3208 pbi
= init_propagate_block_info (test_bb
, test_live
, test_set
, test_set
,
3211 for (insn
= jump
; ; insn
= prev
)
3213 prev
= propagate_one_insn (pbi
, insn
);
3214 if (insn
== earliest
)
3218 free_propagate_block_info (pbi
);
3220 /* We can perform the transformation if
3221 MERGE_SET & (TEST_SET | TEST_LIVE)
3223 TEST_SET & merge_bb->global_live_at_start
3226 bitmap_operation (tmp
, test_set
, test_live
, BITMAP_IOR
);
3227 bitmap_operation (tmp
, tmp
, merge_set
, BITMAP_AND
);
3228 if (bitmap_first_set_bit (tmp
) >= 0)
3231 bitmap_operation (tmp
, test_set
, merge_bb
->global_live_at_start
,
3233 if (bitmap_first_set_bit (tmp
) >= 0)
3237 FREE_REG_SET (merge_set
);
3238 FREE_REG_SET (test_live
);
3239 FREE_REG_SET (test_set
);
3246 /* We don't want to use normal invert_jump or redirect_jump because
3247 we don't want to delete_insn called. Also, we want to do our own
3248 change group management. */
3250 old_dest
= JUMP_LABEL (jump
);
3251 if (other_bb
!= new_dest
)
3253 new_label
= block_label (new_dest
);
3255 ? ! invert_jump_1 (jump
, new_label
)
3256 : ! redirect_jump_1 (jump
, new_label
))
3260 if (! apply_change_group ())
3263 if (other_bb
!= new_dest
)
3266 LABEL_NUSES (old_dest
) -= 1;
3268 LABEL_NUSES (new_label
) += 1;
3269 JUMP_LABEL (jump
) = new_label
;
3271 invert_br_probabilities (jump
);
3273 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3276 gcov_type count
, probability
;
3277 count
= BRANCH_EDGE (test_bb
)->count
;
3278 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3279 FALLTHRU_EDGE (test_bb
)->count
= count
;
3280 probability
= BRANCH_EDGE (test_bb
)->probability
;
3281 BRANCH_EDGE (test_bb
)->probability
3282 = FALLTHRU_EDGE (test_bb
)->probability
;
3283 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3284 update_br_prob_note (test_bb
);
3288 /* Move the insns out of MERGE_BB to before the branch. */
3291 if (end
== BB_END (merge_bb
))
3292 BB_END (merge_bb
) = PREV_INSN (head
);
3294 if (squeeze_notes (&head
, &end
))
3297 reorder_insns (head
, end
, PREV_INSN (earliest
));
3300 /* Remove the jump and edge if we can. */
3301 if (other_bb
== new_dest
)
3304 remove_edge (BRANCH_EDGE (test_bb
));
3305 /* ??? Can't merge blocks here, as then_bb is still in use.
3306 At minimum, the merge will get done just before bb-reorder. */
3316 /* Main entry point for all if-conversion. */
3319 if_convert (int x_life_data_ok
)
3324 num_possible_if_blocks
= 0;
3325 num_updated_if_blocks
= 0;
3326 num_true_changes
= 0;
3327 life_data_ok
= (x_life_data_ok
!= 0);
3329 if ((! targetm
.cannot_modify_jumps_p ())
3330 && (!flag_reorder_blocks_and_partition
|| !no_new_pseudos
3331 || !targetm
.have_named_sections
))
3332 mark_loop_exit_edges ();
3334 /* Compute postdominators if we think we'll use them. */
3335 if (HAVE_conditional_execution
|| life_data_ok
)
3336 calculate_dominance_info (CDI_POST_DOMINATORS
);
3341 /* Go through each of the basic blocks looking for things to convert. If we
3342 have conditional execution, we make multiple passes to allow us to handle
3343 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3347 cond_exec_changed_p
= FALSE
;
3350 #ifdef IFCVT_MULTIPLE_DUMPS
3351 if (dump_file
&& pass
> 1)
3352 fprintf (dump_file
, "\n\n========== Pass %d ==========\n", pass
);
3358 while ((new_bb
= find_if_header (bb
, pass
)))
3362 #ifdef IFCVT_MULTIPLE_DUMPS
3363 if (dump_file
&& cond_exec_changed_p
)
3364 print_rtl_with_bb (dump_file
, get_insns ());
3367 while (cond_exec_changed_p
);
3369 #ifdef IFCVT_MULTIPLE_DUMPS
3371 fprintf (dump_file
, "\n\n========== no more changes\n");
3374 free_dominance_info (CDI_POST_DOMINATORS
);
3379 clear_aux_for_blocks ();
3381 /* Rebuild life info for basic blocks that require it. */
3382 if (num_true_changes
&& life_data_ok
)
3384 /* If we allocated new pseudos, we must resize the array for sched1. */
3385 if (max_regno
< max_reg_num ())
3387 max_regno
= max_reg_num ();
3388 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3390 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES
,
3391 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
3392 | PROP_KILL_DEAD_CODE
);
3395 /* Write the final stats. */
3396 if (dump_file
&& num_possible_if_blocks
> 0)
3399 "\n%d possible IF blocks searched.\n",
3400 num_possible_if_blocks
);
3402 "%d IF blocks converted.\n",
3403 num_updated_if_blocks
);
3405 "%d true changes made.\n\n\n",
3409 #ifdef ENABLE_CHECKING
3410 verify_flow_info ();