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
)
1219 /* A conditional move from two memory sources is equivalent to a
1220 conditional on their addresses followed by a load. Don't do this
1221 early because it'll screw alias analysis. Note that we've
1222 already checked for no side effects. */
1223 if (! no_new_pseudos
&& cse_not_expected
1224 && MEM_P (a
) && MEM_P (b
)
1225 && BRANCH_COST
>= 5)
1229 x
= gen_reg_rtx (Pmode
);
1233 /* ??? We could handle this if we knew that a load from A or B could
1234 not fault. This is also true if we've already loaded
1235 from the address along the path from ENTRY. */
1236 else if (may_trap_p (a
) || may_trap_p (b
))
1239 /* if (test) x = a + b; else x = c - d;
1246 code
= GET_CODE (if_info
->cond
);
1247 insn_a
= if_info
->insn_a
;
1248 insn_b
= if_info
->insn_b
;
1250 /* Possibly rearrange operands to make things come out more natural. */
1251 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1254 if (rtx_equal_p (b
, x
))
1256 else if (general_operand (b
, GET_MODE (b
)))
1261 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1262 tmp
= a
, a
= b
, b
= tmp
;
1263 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1269 /* If either operand is complex, load it into a register first.
1270 The best way to do this is to copy the original insn. In this
1271 way we preserve any clobbers etc that the insn may have had.
1272 This is of course not possible in the IS_MEM case. */
1273 if (! general_operand (a
, GET_MODE (a
)))
1278 goto end_seq_and_fail
;
1282 tmp
= gen_reg_rtx (GET_MODE (a
));
1283 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1286 goto end_seq_and_fail
;
1289 a
= gen_reg_rtx (GET_MODE (a
));
1290 tmp
= copy_rtx (insn_a
);
1291 set
= single_set (tmp
);
1293 tmp
= emit_insn (PATTERN (tmp
));
1295 if (recog_memoized (tmp
) < 0)
1296 goto end_seq_and_fail
;
1298 if (! general_operand (b
, GET_MODE (b
)))
1303 goto end_seq_and_fail
;
1307 tmp
= gen_reg_rtx (GET_MODE (b
));
1308 tmp
= emit_insn (gen_rtx_SET (VOIDmode
,
1313 goto end_seq_and_fail
;
1316 b
= gen_reg_rtx (GET_MODE (b
));
1317 tmp
= copy_rtx (insn_b
);
1318 set
= single_set (tmp
);
1320 tmp
= emit_insn (PATTERN (tmp
));
1322 if (recog_memoized (tmp
) < 0)
1323 goto end_seq_and_fail
;
1326 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1327 XEXP (if_info
->cond
, 1), a
, b
);
1330 goto end_seq_and_fail
;
1332 /* If we're handling a memory for above, emit the load now. */
1335 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1337 /* Copy over flags as appropriate. */
1338 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1339 MEM_VOLATILE_P (tmp
) = 1;
1340 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1341 MEM_IN_STRUCT_P (tmp
) = 1;
1342 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1343 MEM_SCALAR_P (tmp
) = 1;
1344 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1345 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1347 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1349 noce_emit_move_insn (if_info
->x
, tmp
);
1351 else if (target
!= x
)
1352 noce_emit_move_insn (x
, target
);
1354 tmp
= end_ifcvt_sequence (if_info
);
1358 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1366 /* For most cases, the simplified condition we found is the best
1367 choice, but this is not the case for the min/max/abs transforms.
1368 For these we wish to know that it is A or B in the condition. */
1371 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1374 rtx cond
, set
, insn
;
1377 /* If target is already mentioned in the known condition, return it. */
1378 if (reg_mentioned_p (target
, if_info
->cond
))
1380 *earliest
= if_info
->cond_earliest
;
1381 return if_info
->cond
;
1384 set
= pc_set (if_info
->jump
);
1385 cond
= XEXP (SET_SRC (set
), 0);
1387 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1388 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1390 /* If we're looking for a constant, try to make the conditional
1391 have that constant in it. There are two reasons why it may
1392 not have the constant we want:
1394 1. GCC may have needed to put the constant in a register, because
1395 the target can't compare directly against that constant. For
1396 this case, we look for a SET immediately before the comparison
1397 that puts a constant in that register.
1399 2. GCC may have canonicalized the conditional, for example
1400 replacing "if x < 4" with "if x <= 3". We can undo that (or
1401 make equivalent types of changes) to get the constants we need
1402 if they're off by one in the right direction. */
1404 if (GET_CODE (target
) == CONST_INT
)
1406 enum rtx_code code
= GET_CODE (if_info
->cond
);
1407 rtx op_a
= XEXP (if_info
->cond
, 0);
1408 rtx op_b
= XEXP (if_info
->cond
, 1);
1411 /* First, look to see if we put a constant in a register. */
1412 prev_insn
= PREV_INSN (if_info
->cond_earliest
);
1414 && INSN_P (prev_insn
)
1415 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1417 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1419 src
= SET_SRC (PATTERN (prev_insn
));
1420 if (GET_CODE (src
) == CONST_INT
)
1422 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1424 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1427 if (GET_CODE (op_a
) == CONST_INT
)
1432 code
= swap_condition (code
);
1437 /* Now, look to see if we can get the right constant by
1438 adjusting the conditional. */
1439 if (GET_CODE (op_b
) == CONST_INT
)
1441 HOST_WIDE_INT desired_val
= INTVAL (target
);
1442 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1447 if (actual_val
== desired_val
+ 1)
1450 op_b
= GEN_INT (desired_val
);
1454 if (actual_val
== desired_val
- 1)
1457 op_b
= GEN_INT (desired_val
);
1461 if (actual_val
== desired_val
- 1)
1464 op_b
= GEN_INT (desired_val
);
1468 if (actual_val
== desired_val
+ 1)
1471 op_b
= GEN_INT (desired_val
);
1479 /* If we made any changes, generate a new conditional that is
1480 equivalent to what we started with, but has the right
1482 if (code
!= GET_CODE (if_info
->cond
)
1483 || op_a
!= XEXP (if_info
->cond
, 0)
1484 || op_b
!= XEXP (if_info
->cond
, 1))
1486 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1487 *earliest
= if_info
->cond_earliest
;
1492 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1493 earliest
, target
, false, true);
1494 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1497 /* We almost certainly searched back to a different place.
1498 Need to re-verify correct lifetimes. */
1500 /* X may not be mentioned in the range (cond_earliest, jump]. */
1501 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1502 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1505 /* A and B may not be modified in the range [cond_earliest, jump). */
1506 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1508 && (modified_in_p (if_info
->a
, insn
)
1509 || modified_in_p (if_info
->b
, insn
)))
1515 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1518 noce_try_minmax (struct noce_if_info
*if_info
)
1520 rtx cond
, earliest
, target
, seq
;
1521 enum rtx_code code
, op
;
1524 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1528 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1529 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1530 to get the target to tell us... */
1531 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1532 || HONOR_NANS (GET_MODE (if_info
->x
)))
1535 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1539 /* Verify the condition is of the form we expect, and canonicalize
1540 the comparison code. */
1541 code
= GET_CODE (cond
);
1542 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1544 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1547 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1549 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1551 code
= swap_condition (code
);
1556 /* Determine what sort of operation this is. Note that the code is for
1557 a taken branch, so the code->operation mapping appears backwards. */
1590 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1591 if_info
->a
, if_info
->b
,
1592 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1598 if (target
!= if_info
->x
)
1599 noce_emit_move_insn (if_info
->x
, target
);
1601 seq
= end_ifcvt_sequence (if_info
);
1605 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1606 if_info
->cond
= cond
;
1607 if_info
->cond_earliest
= earliest
;
1612 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1615 noce_try_abs (struct noce_if_info
*if_info
)
1617 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1620 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1624 /* Recognize A and B as constituting an ABS or NABS. */
1627 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1629 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1631 c
= a
; a
= b
; b
= c
;
1637 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1641 /* Verify the condition is of the form we expect. */
1642 if (rtx_equal_p (XEXP (cond
, 0), b
))
1644 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1649 /* Verify that C is zero. Search backward through the block for
1650 a REG_EQUAL note if necessary. */
1653 rtx insn
, note
= NULL
;
1654 for (insn
= earliest
;
1655 insn
!= BB_HEAD (if_info
->test_bb
);
1656 insn
= PREV_INSN (insn
))
1658 && ((note
= find_reg_note (insn
, REG_EQUAL
, c
))
1659 || (note
= find_reg_note (insn
, REG_EQUIV
, c
))))
1666 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1667 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1668 c
= get_pool_constant (XEXP (c
, 0));
1670 /* Work around funny ideas get_condition has wrt canonicalization.
1671 Note that these rtx constants are known to be CONST_INT, and
1672 therefore imply integer comparisons. */
1673 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1675 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1677 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1680 /* Determine what sort of operation this is. */
1681 switch (GET_CODE (cond
))
1700 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
1702 /* ??? It's a quandary whether cmove would be better here, especially
1703 for integers. Perhaps combine will clean things up. */
1704 if (target
&& negate
)
1705 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1713 if (target
!= if_info
->x
)
1714 noce_emit_move_insn (if_info
->x
, target
);
1716 seq
= end_ifcvt_sequence (if_info
);
1720 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1721 if_info
->cond
= cond
;
1722 if_info
->cond_earliest
= earliest
;
1727 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1730 noce_try_sign_mask (struct noce_if_info
*if_info
)
1732 rtx cond
, t
, m
, c
, seq
;
1733 enum machine_mode mode
;
1739 cond
= if_info
->cond
;
1740 code
= GET_CODE (cond
);
1745 if (if_info
->a
== const0_rtx
)
1747 if ((code
== LT
&& c
== const0_rtx
)
1748 || (code
== LE
&& c
== constm1_rtx
))
1751 else if (if_info
->b
== const0_rtx
)
1753 if ((code
== GE
&& c
== const0_rtx
)
1754 || (code
== GT
&& c
== constm1_rtx
))
1758 if (! t
|| side_effects_p (t
))
1761 /* We currently don't handle different modes. */
1762 mode
= GET_MODE (t
);
1763 if (GET_MODE (m
) != mode
)
1766 /* This is only profitable if T is cheap, or T is unconditionally
1767 executed/evaluated in the original insn sequence. */
1768 if (rtx_cost (t
, SET
) >= COSTS_N_INSNS (2)
1769 && (!if_info
->b_unconditional
1770 || t
!= if_info
->b
))
1774 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1775 "(signed) m >> 31" directly. This benefits targets with specialized
1776 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1777 m
= emit_store_flag (gen_reg_rtx (mode
), LT
, m
, const0_rtx
, mode
, 0, -1);
1778 t
= m
? expand_binop (mode
, and_optab
, m
, t
, NULL_RTX
, 0, OPTAB_DIRECT
)
1787 noce_emit_move_insn (if_info
->x
, t
);
1789 seq
= end_ifcvt_sequence (if_info
);
1793 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1798 /* Similar to get_condition, only the resulting condition must be
1799 valid at JUMP, instead of at EARLIEST. */
1802 noce_get_condition (rtx jump
, rtx
*earliest
)
1807 if (! any_condjump_p (jump
))
1810 set
= pc_set (jump
);
1812 /* If this branches to JUMP_LABEL when the condition is false,
1813 reverse the condition. */
1814 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1815 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
1817 /* If the condition variable is a register and is MODE_INT, accept it. */
1819 cond
= XEXP (SET_SRC (set
), 0);
1820 tmp
= XEXP (cond
, 0);
1821 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
1826 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
1827 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
1831 /* Otherwise, fall back on canonicalize_condition to do the dirty
1832 work of manipulating MODE_CC values and COMPARE rtx codes. */
1833 return canonicalize_condition (jump
, cond
, reverse
, earliest
,
1834 NULL_RTX
, false, true);
1837 /* Return true if OP is ok for if-then-else processing. */
1840 noce_operand_ok (rtx op
)
1842 /* We special-case memories, so handle any of them with
1843 no address side effects. */
1845 return ! side_effects_p (XEXP (op
, 0));
1847 if (side_effects_p (op
))
1850 return ! may_trap_p (op
);
1853 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1854 without using conditional execution. Return TRUE if we were
1855 successful at converting the block. */
1858 noce_process_if_block (struct ce_if_block
* ce_info
)
1860 basic_block test_bb
= ce_info
->test_bb
; /* test block */
1861 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1862 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1863 struct noce_if_info if_info
;
1866 rtx orig_x
, x
, a
, b
;
1869 /* We're looking for patterns of the form
1871 (1) if (...) x = a; else x = b;
1872 (2) x = b; if (...) x = a;
1873 (3) if (...) x = a; // as if with an initial x = x.
1875 The later patterns require jumps to be more expensive.
1877 ??? For future expansion, look for multiple X in such patterns. */
1879 /* If test is comprised of && or || elements, don't handle it unless it is
1880 the special case of && elements without an ELSE block. */
1881 if (ce_info
->num_multiple_test_blocks
)
1883 if (else_bb
|| ! ce_info
->and_and_p
)
1886 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
1887 ce_info
->num_multiple_test_blocks
= 0;
1888 ce_info
->num_and_and_blocks
= 0;
1889 ce_info
->num_or_or_blocks
= 0;
1892 /* If this is not a standard conditional jump, we can't parse it. */
1893 jump
= BB_END (test_bb
);
1894 cond
= noce_get_condition (jump
, &if_info
.cond_earliest
);
1898 /* If the conditional jump is more than just a conditional
1899 jump, then we can not do if-conversion on this block. */
1900 if (! onlyjump_p (jump
))
1903 /* We must be comparing objects whose modes imply the size. */
1904 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
1907 /* Look for one of the potential sets. */
1908 insn_a
= first_active_insn (then_bb
);
1910 || insn_a
!= last_active_insn (then_bb
, FALSE
)
1911 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
1914 x
= SET_DEST (set_a
);
1915 a
= SET_SRC (set_a
);
1917 /* Look for the other potential set. Make sure we've got equivalent
1919 /* ??? This is overconservative. Storing to two different mems is
1920 as easy as conditionally computing the address. Storing to a
1921 single mem merely requires a scratch memory to use as one of the
1922 destination addresses; often the memory immediately below the
1923 stack pointer is available for this. */
1927 insn_b
= first_active_insn (else_bb
);
1929 || insn_b
!= last_active_insn (else_bb
, FALSE
)
1930 || (set_b
= single_set (insn_b
)) == NULL_RTX
1931 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
1936 insn_b
= prev_nonnote_insn (if_info
.cond_earliest
);
1937 /* We're going to be moving the evaluation of B down from above
1938 COND_EARLIEST to JUMP. Make sure the relevant data is still
1941 || !NONJUMP_INSN_P (insn_b
)
1942 || (set_b
= single_set (insn_b
)) == NULL_RTX
1943 || ! rtx_equal_p (x
, SET_DEST (set_b
))
1944 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
1945 || modified_between_p (SET_SRC (set_b
),
1946 PREV_INSN (if_info
.cond_earliest
), jump
)
1947 /* Likewise with X. In particular this can happen when
1948 noce_get_condition looks farther back in the instruction
1949 stream than one might expect. */
1950 || reg_overlap_mentioned_p (x
, cond
)
1951 || reg_overlap_mentioned_p (x
, a
)
1952 || modified_between_p (x
, PREV_INSN (if_info
.cond_earliest
), jump
))
1953 insn_b
= set_b
= NULL_RTX
;
1956 /* If x has side effects then only the if-then-else form is safe to
1957 convert. But even in that case we would need to restore any notes
1958 (such as REG_INC) at then end. That can be tricky if
1959 noce_emit_move_insn expands to more than one insn, so disable the
1960 optimization entirely for now if there are side effects. */
1961 if (side_effects_p (x
))
1964 b
= (set_b
? SET_SRC (set_b
) : x
);
1966 /* Only operate on register destinations, and even then avoid extending
1967 the lifetime of hard registers on small register class machines. */
1970 || (SMALL_REGISTER_CLASSES
1971 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
1973 if (no_new_pseudos
|| GET_MODE (x
) == BLKmode
)
1975 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
1976 ? XEXP (x
, 0) : x
));
1979 /* Don't operate on sources that may trap or are volatile. */
1980 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
1983 /* Set up the info block for our subroutines. */
1984 if_info
.test_bb
= test_bb
;
1985 if_info
.cond
= cond
;
1986 if_info
.jump
= jump
;
1987 if_info
.insn_a
= insn_a
;
1988 if_info
.insn_b
= insn_b
;
1992 if_info
.b_unconditional
= else_bb
== 0;
1994 /* Try optimizations in some approximation of a useful order. */
1995 /* ??? Should first look to see if X is live incoming at all. If it
1996 isn't, we don't need anything but an unconditional set. */
1998 /* Look and see if A and B are really the same. Avoid creating silly
1999 cmove constructs that no one will fix up later. */
2000 if (rtx_equal_p (a
, b
))
2002 /* If we have an INSN_B, we don't have to create any new rtl. Just
2003 move the instruction that we already have. If we don't have an
2004 INSN_B, that means that A == X, and we've got a noop move. In
2005 that case don't do anything and let the code below delete INSN_A. */
2006 if (insn_b
&& else_bb
)
2010 if (else_bb
&& insn_b
== BB_END (else_bb
))
2011 BB_END (else_bb
) = PREV_INSN (insn_b
);
2012 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
2014 /* If there was a REG_EQUAL note, delete it since it may have been
2015 true due to this insn being after a jump. */
2016 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
2017 remove_note (insn_b
, note
);
2021 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2022 x must be executed twice. */
2023 else if (insn_b
&& side_effects_p (orig_x
))
2030 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2031 for most optimizations if writing to x may trap, i.e. it's a memory
2032 other than a static var or a stack slot. */
2035 && ! MEM_NOTRAP_P (orig_x
)
2036 && rtx_addr_can_trap_p (XEXP (orig_x
, 0)))
2038 if (HAVE_conditional_move
)
2040 if (noce_try_cmove (&if_info
))
2042 if (! HAVE_conditional_execution
2043 && noce_try_cmove_arith (&if_info
))
2049 if (noce_try_move (&if_info
))
2051 if (noce_try_store_flag (&if_info
))
2053 if (noce_try_minmax (&if_info
))
2055 if (noce_try_abs (&if_info
))
2057 if (HAVE_conditional_move
2058 && noce_try_cmove (&if_info
))
2060 if (! HAVE_conditional_execution
)
2062 if (noce_try_store_flag_constants (&if_info
))
2064 if (noce_try_addcc (&if_info
))
2066 if (noce_try_store_flag_mask (&if_info
))
2068 if (HAVE_conditional_move
2069 && noce_try_cmove_arith (&if_info
))
2071 if (noce_try_sign_mask (&if_info
))
2078 /* The original sets may now be killed. */
2079 delete_insn (insn_a
);
2081 /* Several special cases here: First, we may have reused insn_b above,
2082 in which case insn_b is now NULL. Second, we want to delete insn_b
2083 if it came from the ELSE block, because follows the now correct
2084 write that appears in the TEST block. However, if we got insn_b from
2085 the TEST block, it may in fact be loading data needed for the comparison.
2086 We'll let life_analysis remove the insn if it's really dead. */
2087 if (insn_b
&& else_bb
)
2088 delete_insn (insn_b
);
2090 /* The new insns will have been inserted immediately before the jump. We
2091 should be able to remove the jump with impunity, but the condition itself
2092 may have been modified by gcse to be shared across basic blocks. */
2095 /* If we used a temporary, fix it up now. */
2099 noce_emit_move_insn (orig_x
, x
);
2100 insn_b
= get_insns ();
2101 set_used_flags (orig_x
);
2102 unshare_all_rtl_in_chain (insn_b
);
2105 emit_insn_after_setloc (insn_b
, BB_END (test_bb
), INSN_LOCATOR (insn_a
));
2108 /* Merge the blocks! */
2109 merge_if_block (ce_info
);
2114 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2115 straight line code. Return true if successful. */
2118 process_if_block (struct ce_if_block
* ce_info
)
2120 if (! reload_completed
2121 && noce_process_if_block (ce_info
))
2124 if (HAVE_conditional_execution
&& reload_completed
)
2126 /* If we have && and || tests, try to first handle combining the && and
2127 || tests into the conditional code, and if that fails, go back and
2128 handle it without the && and ||, which at present handles the && case
2129 if there was no ELSE block. */
2130 if (cond_exec_process_if_block (ce_info
, TRUE
))
2133 if (ce_info
->num_multiple_test_blocks
)
2137 if (cond_exec_process_if_block (ce_info
, FALSE
))
2145 /* Merge the blocks and mark for local life update. */
2148 merge_if_block (struct ce_if_block
* ce_info
)
2150 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
2151 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
2152 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
2153 basic_block join_bb
= ce_info
->join_bb
; /* join block */
2154 basic_block combo_bb
;
2156 /* All block merging is done into the lower block numbers. */
2160 /* Merge any basic blocks to handle && and || subtests. Each of
2161 the blocks are on the fallthru path from the predecessor block. */
2162 if (ce_info
->num_multiple_test_blocks
> 0)
2164 basic_block bb
= test_bb
;
2165 basic_block last_test_bb
= ce_info
->last_test_bb
;
2166 basic_block fallthru
= block_fallthru (bb
);
2171 fallthru
= block_fallthru (bb
);
2172 merge_blocks (combo_bb
, bb
);
2175 while (bb
!= last_test_bb
);
2178 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2179 label, but it might if there were || tests. That label's count should be
2180 zero, and it normally should be removed. */
2184 if (combo_bb
->global_live_at_end
)
2185 COPY_REG_SET (combo_bb
->global_live_at_end
,
2186 then_bb
->global_live_at_end
);
2187 merge_blocks (combo_bb
, then_bb
);
2191 /* The ELSE block, if it existed, had a label. That label count
2192 will almost always be zero, but odd things can happen when labels
2193 get their addresses taken. */
2196 merge_blocks (combo_bb
, else_bb
);
2200 /* If there was no join block reported, that means it was not adjacent
2201 to the others, and so we cannot merge them. */
2205 rtx last
= BB_END (combo_bb
);
2207 /* The outgoing edge for the current COMBO block should already
2208 be correct. Verify this. */
2209 if (combo_bb
->succ
== NULL_EDGE
)
2211 if (find_reg_note (last
, REG_NORETURN
, NULL
))
2213 else if (NONJUMP_INSN_P (last
)
2214 && GET_CODE (PATTERN (last
)) == TRAP_IF
2215 && TRAP_CONDITION (PATTERN (last
)) == const_true_rtx
)
2221 /* There should still be something at the end of the THEN or ELSE
2222 blocks taking us to our final destination. */
2223 else if (JUMP_P (last
))
2225 else if (combo_bb
->succ
->dest
== EXIT_BLOCK_PTR
2227 && SIBLING_CALL_P (last
))
2229 else if ((combo_bb
->succ
->flags
& EDGE_EH
)
2230 && can_throw_internal (last
))
2236 /* The JOIN block may have had quite a number of other predecessors too.
2237 Since we've already merged the TEST, THEN and ELSE blocks, we should
2238 have only one remaining edge from our if-then-else diamond. If there
2239 is more than one remaining edge, it must come from elsewhere. There
2240 may be zero incoming edges if the THEN block didn't actually join
2241 back up (as with a call to abort). */
2242 else if ((join_bb
->pred
== NULL
2243 || join_bb
->pred
->pred_next
== NULL
)
2244 && join_bb
!= EXIT_BLOCK_PTR
)
2246 /* We can merge the JOIN. */
2247 if (combo_bb
->global_live_at_end
)
2248 COPY_REG_SET (combo_bb
->global_live_at_end
,
2249 join_bb
->global_live_at_end
);
2251 merge_blocks (combo_bb
, join_bb
);
2256 /* We cannot merge the JOIN. */
2258 /* The outgoing edge for the current COMBO block should already
2259 be correct. Verify this. */
2260 if (combo_bb
->succ
->succ_next
!= NULL_EDGE
2261 || combo_bb
->succ
->dest
!= join_bb
)
2264 /* Remove the jump and cruft from the end of the COMBO block. */
2265 if (join_bb
!= EXIT_BLOCK_PTR
)
2266 tidy_fallthru_edge (combo_bb
->succ
);
2269 num_updated_if_blocks
++;
2272 /* Find a block ending in a simple IF condition and try to transform it
2273 in some way. When converting a multi-block condition, put the new code
2274 in the first such block and delete the rest. Return a pointer to this
2275 first block if some transformation was done. Return NULL otherwise. */
2278 find_if_header (basic_block test_bb
, int pass
)
2280 ce_if_block_t ce_info
;
2284 /* The kind of block we're looking for has exactly two successors. */
2285 if ((then_edge
= test_bb
->succ
) == NULL_EDGE
2286 || (else_edge
= then_edge
->succ_next
) == NULL_EDGE
2287 || else_edge
->succ_next
!= NULL_EDGE
)
2290 /* Neither edge should be abnormal. */
2291 if ((then_edge
->flags
& EDGE_COMPLEX
)
2292 || (else_edge
->flags
& EDGE_COMPLEX
))
2295 /* Nor exit the loop. */
2296 if ((then_edge
->flags
& EDGE_LOOP_EXIT
)
2297 || (else_edge
->flags
& EDGE_LOOP_EXIT
))
2300 /* The THEN edge is canonically the one that falls through. */
2301 if (then_edge
->flags
& EDGE_FALLTHRU
)
2303 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2306 else_edge
= then_edge
;
2310 /* Otherwise this must be a multiway branch of some sort. */
2313 memset (&ce_info
, '\0', sizeof (ce_info
));
2314 ce_info
.test_bb
= test_bb
;
2315 ce_info
.then_bb
= then_edge
->dest
;
2316 ce_info
.else_bb
= else_edge
->dest
;
2317 ce_info
.pass
= pass
;
2319 #ifdef IFCVT_INIT_EXTRA_FIELDS
2320 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2323 if (find_if_block (&ce_info
))
2326 if (HAVE_trap
&& HAVE_conditional_trap
2327 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2330 if (dom_computed
[CDI_POST_DOMINATORS
] >= DOM_NO_FAST_QUERY
2331 && (! HAVE_conditional_execution
|| reload_completed
))
2333 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2335 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2343 fprintf (dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2344 return ce_info
.test_bb
;
2347 /* Return true if a block has two edges, one of which falls through to the next
2348 block, and the other jumps to a specific block, so that we can tell if the
2349 block is part of an && test or an || test. Returns either -1 or the number
2350 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2353 block_jumps_and_fallthru_p (basic_block cur_bb
, basic_block target_bb
)
2356 int fallthru_p
= FALSE
;
2362 if (!cur_bb
|| !target_bb
)
2365 /* If no edges, obviously it doesn't jump or fallthru. */
2366 if (cur_bb
->succ
== NULL_EDGE
)
2369 for (cur_edge
= cur_bb
->succ
;
2370 cur_edge
!= NULL_EDGE
;
2371 cur_edge
= cur_edge
->succ_next
)
2373 if (cur_edge
->flags
& EDGE_COMPLEX
)
2374 /* Anything complex isn't what we want. */
2377 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2380 else if (cur_edge
->dest
== target_bb
)
2387 if ((jump_p
& fallthru_p
) == 0)
2390 /* Don't allow calls in the block, since this is used to group && and ||
2391 together for conditional execution support. ??? we should support
2392 conditional execution support across calls for IA-64 some day, but
2393 for now it makes the code simpler. */
2394 end
= BB_END (cur_bb
);
2395 insn
= BB_HEAD (cur_bb
);
2397 while (insn
!= NULL_RTX
)
2404 && GET_CODE (PATTERN (insn
)) != USE
2405 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
2411 insn
= NEXT_INSN (insn
);
2417 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2418 block. If so, we'll try to convert the insns to not require the branch.
2419 Return TRUE if we were successful at converting the block. */
2422 find_if_block (struct ce_if_block
* ce_info
)
2424 basic_block test_bb
= ce_info
->test_bb
;
2425 basic_block then_bb
= ce_info
->then_bb
;
2426 basic_block else_bb
= ce_info
->else_bb
;
2427 basic_block join_bb
= NULL_BLOCK
;
2428 edge then_succ
= then_bb
->succ
;
2429 edge else_succ
= else_bb
->succ
;
2430 int then_predecessors
;
2431 int else_predecessors
;
2435 ce_info
->last_test_bb
= test_bb
;
2437 /* Discover if any fall through predecessors of the current test basic block
2438 were && tests (which jump to the else block) or || tests (which jump to
2440 if (HAVE_conditional_execution
&& reload_completed
2441 && test_bb
->pred
!= NULL_EDGE
2442 && test_bb
->pred
->pred_next
== NULL_EDGE
2443 && test_bb
->pred
->flags
== EDGE_FALLTHRU
)
2445 basic_block bb
= test_bb
->pred
->src
;
2446 basic_block target_bb
;
2447 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
2450 /* Determine if the preceding block is an && or || block. */
2451 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
2453 ce_info
->and_and_p
= TRUE
;
2454 target_bb
= else_bb
;
2456 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
2458 ce_info
->and_and_p
= FALSE
;
2459 target_bb
= then_bb
;
2462 target_bb
= NULL_BLOCK
;
2464 if (target_bb
&& n_insns
<= max_insns
)
2466 int total_insns
= 0;
2469 ce_info
->last_test_bb
= test_bb
;
2471 /* Found at least one && or || block, look for more. */
2474 ce_info
->test_bb
= test_bb
= bb
;
2475 total_insns
+= n_insns
;
2478 if (bb
->pred
== NULL_EDGE
|| bb
->pred
->pred_next
!= NULL_EDGE
)
2482 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
2484 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
2486 ce_info
->num_multiple_test_blocks
= blocks
;
2487 ce_info
->num_multiple_test_insns
= total_insns
;
2489 if (ce_info
->and_and_p
)
2490 ce_info
->num_and_and_blocks
= blocks
;
2492 ce_info
->num_or_or_blocks
= blocks
;
2496 /* Count the number of edges the THEN and ELSE blocks have. */
2497 then_predecessors
= 0;
2498 for (cur_edge
= then_bb
->pred
;
2499 cur_edge
!= NULL_EDGE
;
2500 cur_edge
= cur_edge
->pred_next
)
2502 then_predecessors
++;
2503 if (cur_edge
->flags
& EDGE_COMPLEX
)
2507 else_predecessors
= 0;
2508 for (cur_edge
= else_bb
->pred
;
2509 cur_edge
!= NULL_EDGE
;
2510 cur_edge
= cur_edge
->pred_next
)
2512 else_predecessors
++;
2513 if (cur_edge
->flags
& EDGE_COMPLEX
)
2517 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2518 other than any || blocks which jump to the THEN block. */
2519 if ((then_predecessors
- ce_info
->num_or_or_blocks
) != 1)
2522 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2523 if (then_succ
!= NULL_EDGE
2524 && (then_succ
->succ_next
!= NULL_EDGE
2525 || (then_succ
->flags
& EDGE_COMPLEX
)
2526 || (flow2_completed
&& tablejump_p (BB_END (then_bb
), NULL
, NULL
))))
2529 /* If the THEN block has no successors, conditional execution can still
2530 make a conditional call. Don't do this unless the ELSE block has
2531 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2532 Check for the last insn of the THEN block being an indirect jump, which
2533 is listed as not having any successors, but confuses the rest of the CE
2534 code processing. ??? we should fix this in the future. */
2535 if (then_succ
== NULL
)
2537 if (else_bb
->pred
->pred_next
== NULL_EDGE
)
2539 rtx last_insn
= BB_END (then_bb
);
2542 && NOTE_P (last_insn
)
2543 && last_insn
!= BB_HEAD (then_bb
))
2544 last_insn
= PREV_INSN (last_insn
);
2547 && JUMP_P (last_insn
)
2548 && ! simplejump_p (last_insn
))
2552 else_bb
= NULL_BLOCK
;
2558 /* If the THEN block's successor is the other edge out of the TEST block,
2559 then we have an IF-THEN combo without an ELSE. */
2560 else if (then_succ
->dest
== else_bb
)
2563 else_bb
= NULL_BLOCK
;
2566 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2567 has exactly one predecessor and one successor, and the outgoing edge
2568 is not complex, then we have an IF-THEN-ELSE combo. */
2569 else if (else_succ
!= NULL_EDGE
2570 && then_succ
->dest
== else_succ
->dest
2571 && else_bb
->pred
->pred_next
== NULL_EDGE
2572 && else_succ
->succ_next
== NULL_EDGE
2573 && ! (else_succ
->flags
& EDGE_COMPLEX
)
2574 && ! (flow2_completed
&& tablejump_p (BB_END (else_bb
), NULL
, NULL
)))
2575 join_bb
= else_succ
->dest
;
2577 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2581 num_possible_if_blocks
++;
2586 "\nIF-THEN%s block found, pass %d, start block %d "
2587 "[insn %d], then %d [%d]",
2588 (else_bb
) ? "-ELSE" : "",
2591 BB_HEAD (test_bb
) ? (int)INSN_UID (BB_HEAD (test_bb
)) : -1,
2593 BB_HEAD (then_bb
) ? (int)INSN_UID (BB_HEAD (then_bb
)) : -1);
2596 fprintf (dump_file
, ", else %d [%d]",
2598 BB_HEAD (else_bb
) ? (int)INSN_UID (BB_HEAD (else_bb
)) : -1);
2600 fprintf (dump_file
, ", join %d [%d]",
2602 BB_HEAD (join_bb
) ? (int)INSN_UID (BB_HEAD (join_bb
)) : -1);
2604 if (ce_info
->num_multiple_test_blocks
> 0)
2605 fprintf (dump_file
, ", %d %s block%s last test %d [%d]",
2606 ce_info
->num_multiple_test_blocks
,
2607 (ce_info
->and_and_p
) ? "&&" : "||",
2608 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
2609 ce_info
->last_test_bb
->index
,
2610 ((BB_HEAD (ce_info
->last_test_bb
))
2611 ? (int)INSN_UID (BB_HEAD (ce_info
->last_test_bb
))
2614 fputc ('\n', dump_file
);
2617 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2618 first condition for free, since we've already asserted that there's a
2619 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2620 we checked the FALLTHRU flag, those are already adjacent to the last IF
2622 /* ??? As an enhancement, move the ELSE block. Have to deal with
2623 BLOCK notes, if by no other means than aborting the merge if they
2624 exist. Sticky enough I don't want to think about it now. */
2626 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
2628 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
2636 /* Do the real work. */
2637 ce_info
->else_bb
= else_bb
;
2638 ce_info
->join_bb
= join_bb
;
2640 return process_if_block (ce_info
);
2643 /* Convert a branch over a trap, or a branch
2644 to a trap, into a conditional trap. */
2647 find_cond_trap (basic_block test_bb
, edge then_edge
, edge else_edge
)
2649 basic_block then_bb
= then_edge
->dest
;
2650 basic_block else_bb
= else_edge
->dest
;
2651 basic_block other_bb
, trap_bb
;
2652 rtx trap
, jump
, cond
, cond_earliest
, seq
;
2655 /* Locate the block with the trap instruction. */
2656 /* ??? While we look for no successors, we really ought to allow
2657 EH successors. Need to fix merge_if_block for that to work. */
2658 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
2659 trap_bb
= then_bb
, other_bb
= else_bb
;
2660 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
2661 trap_bb
= else_bb
, other_bb
= then_bb
;
2667 fprintf (dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
2668 test_bb
->index
, trap_bb
->index
);
2671 /* If this is not a standard conditional jump, we can't parse it. */
2672 jump
= BB_END (test_bb
);
2673 cond
= noce_get_condition (jump
, &cond_earliest
);
2677 /* If the conditional jump is more than just a conditional jump, then
2678 we can not do if-conversion on this block. */
2679 if (! onlyjump_p (jump
))
2682 /* We must be comparing objects whose modes imply the size. */
2683 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2686 /* Reverse the comparison code, if necessary. */
2687 code
= GET_CODE (cond
);
2688 if (then_bb
== trap_bb
)
2690 code
= reversed_comparison_code (cond
, jump
);
2691 if (code
== UNKNOWN
)
2695 /* Attempt to generate the conditional trap. */
2696 seq
= gen_cond_trap (code
, XEXP (cond
, 0),
2698 TRAP_CODE (PATTERN (trap
)));
2704 /* Emit the new insns before cond_earliest. */
2705 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATOR (trap
));
2707 /* Delete the trap block if possible. */
2708 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
2709 if (trap_bb
->pred
== NULL
)
2710 delete_basic_block (trap_bb
);
2712 /* If the non-trap block and the test are now adjacent, merge them.
2713 Otherwise we must insert a direct branch. */
2714 if (test_bb
->next_bb
== other_bb
)
2716 struct ce_if_block new_ce_info
;
2718 memset (&new_ce_info
, '\0', sizeof (new_ce_info
));
2719 new_ce_info
.test_bb
= test_bb
;
2720 new_ce_info
.then_bb
= NULL
;
2721 new_ce_info
.else_bb
= NULL
;
2722 new_ce_info
.join_bb
= other_bb
;
2723 merge_if_block (&new_ce_info
);
2729 lab
= JUMP_LABEL (jump
);
2730 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
2731 LABEL_NUSES (lab
) += 1;
2732 JUMP_LABEL (newjump
) = lab
;
2733 emit_barrier_after (newjump
);
2741 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2745 block_has_only_trap (basic_block bb
)
2749 /* We're not the exit block. */
2750 if (bb
== EXIT_BLOCK_PTR
)
2753 /* The block must have no successors. */
2757 /* The only instruction in the THEN block must be the trap. */
2758 trap
= first_active_insn (bb
);
2759 if (! (trap
== BB_END (bb
)
2760 && GET_CODE (PATTERN (trap
)) == TRAP_IF
2761 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
2767 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2768 transformable, but not necessarily the other. There need be no
2771 Return TRUE if we were successful at converting the block.
2773 Cases we'd like to look at:
2776 if (test) goto over; // x not live
2784 if (! test) goto label;
2787 if (test) goto E; // x not live
2801 (3) // This one's really only interesting for targets that can do
2802 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2803 // it results in multiple branches on a cache line, which often
2804 // does not sit well with predictors.
2806 if (test1) goto E; // predicted not taken
2822 (A) Don't do (2) if the branch is predicted against the block we're
2823 eliminating. Do it anyway if we can eliminate a branch; this requires
2824 that the sole successor of the eliminated block postdominate the other
2827 (B) With CE, on (3) we can steal from both sides of the if, creating
2836 Again, this is most useful if J postdominates.
2838 (C) CE substitutes for helpful life information.
2840 (D) These heuristics need a lot of work. */
2842 /* Tests for case 1 above. */
2845 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2847 basic_block then_bb
= then_edge
->dest
;
2848 basic_block else_bb
= else_edge
->dest
, new_bb
;
2849 edge then_succ
= then_bb
->succ
;
2850 int then_bb_index
, bb_cost
;
2852 /* If we are partitioning hot/cold basic blocks, we don't want to
2853 mess up unconditional or indirect jumps that cross between hot
2856 Basic block partitioning may result in some jumps that appear to
2857 be optimizable (or blocks that appear to be mergeable), but which really
2858 must be left untouched (they are required to make it safely across
2859 partition boundaries). See the comments at the top of
2860 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2862 if (flag_reorder_blocks_and_partition
2863 && ((BB_END (then_bb
)
2864 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2865 || (BB_END (else_bb
)
2866 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2870 /* THEN has one successor. */
2871 if (!then_succ
|| then_succ
->succ_next
!= NULL
)
2874 /* THEN does not fall through, but is not strange either. */
2875 if (then_succ
->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
2878 /* THEN has one predecessor. */
2879 if (then_bb
->pred
->pred_next
!= NULL
)
2882 /* THEN must do something. */
2883 if (forwarder_block_p (then_bb
))
2886 num_possible_if_blocks
++;
2889 "\nIF-CASE-1 found, start %d, then %d\n",
2890 test_bb
->index
, then_bb
->index
);
2892 /* THEN is small. */
2893 bb_cost
= total_bb_rtx_cost (then_bb
);
2894 if (bb_cost
< 0 || bb_cost
>= COSTS_N_INSNS (BRANCH_COST
))
2897 /* Registers set are dead, or are predicable. */
2898 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
2899 then_bb
->succ
->dest
, 1))
2902 /* Conversion went ok, including moving the insns and fixing up the
2903 jump. Adjust the CFG to match. */
2905 bitmap_operation (test_bb
->global_live_at_end
,
2906 else_bb
->global_live_at_start
,
2907 then_bb
->global_live_at_end
, BITMAP_IOR
);
2909 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
), else_bb
);
2910 then_bb_index
= then_bb
->index
;
2911 delete_basic_block (then_bb
);
2913 /* Make rest of code believe that the newly created block is the THEN_BB
2914 block we removed. */
2917 new_bb
->index
= then_bb_index
;
2918 BASIC_BLOCK (then_bb_index
) = new_bb
;
2919 /* Since the fallthru edge was redirected from test_bb to new_bb,
2920 we need to ensure that new_bb is in the same partition as
2921 test bb (you can not fall through across section boundaries). */
2922 BB_COPY_PARTITION (new_bb
, test_bb
);
2924 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2928 num_updated_if_blocks
++;
2933 /* Test for case 2 above. */
2936 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2938 basic_block then_bb
= then_edge
->dest
;
2939 basic_block else_bb
= else_edge
->dest
;
2940 edge else_succ
= else_bb
->succ
;
2944 /* If we are partitioning hot/cold basic blocks, we don't want to
2945 mess up unconditional or indirect jumps that cross between hot
2948 Basic block partitioning may result in some jumps that appear to
2949 be optimizable (or blocks that appear to be mergeable), but which really
2950 must be left untouched (they are required to make it safely across
2951 partition boundaries). See the comments at the top of
2952 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2954 if (flag_reorder_blocks_and_partition
2955 && ((BB_END (then_bb
)
2956 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2957 || (BB_END (else_bb
)
2958 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2962 /* ELSE has one successor. */
2963 if (!else_succ
|| else_succ
->succ_next
!= NULL
)
2966 /* ELSE outgoing edge is not complex. */
2967 if (else_succ
->flags
& EDGE_COMPLEX
)
2970 /* ELSE has one predecessor. */
2971 if (else_bb
->pred
->pred_next
!= NULL
)
2974 /* THEN is not EXIT. */
2975 if (then_bb
->index
< 0)
2978 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2979 note
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
2980 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
2982 else if (else_succ
->dest
->index
< 0
2983 || dominated_by_p (CDI_POST_DOMINATORS
, then_bb
,
2989 num_possible_if_blocks
++;
2992 "\nIF-CASE-2 found, start %d, else %d\n",
2993 test_bb
->index
, else_bb
->index
);
2995 /* ELSE is small. */
2996 bb_cost
= total_bb_rtx_cost (else_bb
);
2997 if (bb_cost
< 0 || bb_cost
>= COSTS_N_INSNS (BRANCH_COST
))
3000 /* Registers set are dead, or are predicable. */
3001 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
3004 /* Conversion went ok, including moving the insns and fixing up the
3005 jump. Adjust the CFG to match. */
3007 bitmap_operation (test_bb
->global_live_at_end
,
3008 then_bb
->global_live_at_start
,
3009 else_bb
->global_live_at_end
, BITMAP_IOR
);
3011 delete_basic_block (else_bb
);
3014 num_updated_if_blocks
++;
3016 /* ??? We may now fallthru from one of THEN's successors into a join
3017 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3022 /* A subroutine of dead_or_predicable called through for_each_rtx.
3023 Return 1 if a memory is found. */
3026 find_memory (rtx
*px
, void *data ATTRIBUTE_UNUSED
)
3031 /* Used by the code above to perform the actual rtl transformations.
3032 Return TRUE if successful.
3034 TEST_BB is the block containing the conditional branch. MERGE_BB
3035 is the block containing the code to manipulate. NEW_DEST is the
3036 label TEST_BB should be branching to after the conversion.
3037 REVERSEP is true if the sense of the branch should be reversed. */
3040 dead_or_predicable (basic_block test_bb
, basic_block merge_bb
,
3041 basic_block other_bb
, basic_block new_dest
, int reversep
)
3043 rtx head
, end
, jump
, earliest
= NULL_RTX
, old_dest
, new_label
= NULL_RTX
;
3045 jump
= BB_END (test_bb
);
3047 /* Find the extent of the real code in the merge block. */
3048 head
= BB_HEAD (merge_bb
);
3049 end
= BB_END (merge_bb
);
3052 head
= NEXT_INSN (head
);
3057 head
= end
= NULL_RTX
;
3060 head
= NEXT_INSN (head
);
3067 head
= end
= NULL_RTX
;
3070 end
= PREV_INSN (end
);
3073 /* Disable handling dead code by conditional execution if the machine needs
3074 to do anything funny with the tests, etc. */
3075 #ifndef IFCVT_MODIFY_TESTS
3076 if (HAVE_conditional_execution
)
3078 /* In the conditional execution case, we have things easy. We know
3079 the condition is reversible. We don't have to check life info
3080 because we're going to conditionally execute the code anyway.
3081 All that's left is making sure the insns involved can actually
3086 cond
= cond_exec_get_condition (jump
);
3090 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
3092 prob_val
= XEXP (prob_val
, 0);
3096 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
3099 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
3102 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
3105 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
3114 /* In the non-conditional execution case, we have to verify that there
3115 are no trapping operations, no calls, no references to memory, and
3116 that any registers modified are dead at the branch site. */
3118 rtx insn
, cond
, prev
;
3119 regset_head merge_set_head
, tmp_head
, test_live_head
, test_set_head
;
3120 regset merge_set
, tmp
, test_live
, test_set
;
3121 struct propagate_block_info
*pbi
;
3124 /* Check for no calls or trapping operations. */
3125 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
3131 if (may_trap_p (PATTERN (insn
)))
3134 /* ??? Even non-trapping memories such as stack frame
3135 references must be avoided. For stores, we collect
3136 no lifetime info; for reads, we'd have to assert
3137 true_dependence false against every store in the
3139 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
3146 if (! any_condjump_p (jump
))
3149 /* Find the extent of the conditional. */
3150 cond
= noce_get_condition (jump
, &earliest
);
3155 MERGE_SET = set of registers set in MERGE_BB
3156 TEST_LIVE = set of registers live at EARLIEST
3157 TEST_SET = set of registers set between EARLIEST and the
3158 end of the block. */
3160 tmp
= INITIALIZE_REG_SET (tmp_head
);
3161 merge_set
= INITIALIZE_REG_SET (merge_set_head
);
3162 test_live
= INITIALIZE_REG_SET (test_live_head
);
3163 test_set
= INITIALIZE_REG_SET (test_set_head
);
3165 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3166 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3167 since we've already asserted that MERGE_BB is small. */
3168 propagate_block (merge_bb
, tmp
, merge_set
, merge_set
, 0);
3170 /* For small register class machines, don't lengthen lifetimes of
3171 hard registers before reload. */
3172 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
3174 EXECUTE_IF_SET_IN_BITMAP
3177 if (i
< FIRST_PSEUDO_REGISTER
3179 && ! global_regs
[i
])
3184 /* For TEST, we're interested in a range of insns, not a whole block.
3185 Moreover, we're interested in the insns live from OTHER_BB. */
3187 COPY_REG_SET (test_live
, other_bb
->global_live_at_start
);
3188 pbi
= init_propagate_block_info (test_bb
, test_live
, test_set
, test_set
,
3191 for (insn
= jump
; ; insn
= prev
)
3193 prev
= propagate_one_insn (pbi
, insn
);
3194 if (insn
== earliest
)
3198 free_propagate_block_info (pbi
);
3200 /* We can perform the transformation if
3201 MERGE_SET & (TEST_SET | TEST_LIVE)
3203 TEST_SET & merge_bb->global_live_at_start
3206 bitmap_operation (tmp
, test_set
, test_live
, BITMAP_IOR
);
3207 bitmap_operation (tmp
, tmp
, merge_set
, BITMAP_AND
);
3208 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
3210 bitmap_operation (tmp
, test_set
, merge_bb
->global_live_at_start
,
3212 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
3215 FREE_REG_SET (merge_set
);
3216 FREE_REG_SET (test_live
);
3217 FREE_REG_SET (test_set
);
3224 /* We don't want to use normal invert_jump or redirect_jump because
3225 we don't want to delete_insn called. Also, we want to do our own
3226 change group management. */
3228 old_dest
= JUMP_LABEL (jump
);
3229 if (other_bb
!= new_dest
)
3231 new_label
= block_label (new_dest
);
3233 ? ! invert_jump_1 (jump
, new_label
)
3234 : ! redirect_jump_1 (jump
, new_label
))
3238 if (! apply_change_group ())
3241 if (other_bb
!= new_dest
)
3244 LABEL_NUSES (old_dest
) -= 1;
3246 LABEL_NUSES (new_label
) += 1;
3247 JUMP_LABEL (jump
) = new_label
;
3249 invert_br_probabilities (jump
);
3251 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3254 gcov_type count
, probability
;
3255 count
= BRANCH_EDGE (test_bb
)->count
;
3256 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3257 FALLTHRU_EDGE (test_bb
)->count
= count
;
3258 probability
= BRANCH_EDGE (test_bb
)->probability
;
3259 BRANCH_EDGE (test_bb
)->probability
3260 = FALLTHRU_EDGE (test_bb
)->probability
;
3261 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3262 update_br_prob_note (test_bb
);
3266 /* Move the insns out of MERGE_BB to before the branch. */
3269 if (end
== BB_END (merge_bb
))
3270 BB_END (merge_bb
) = PREV_INSN (head
);
3272 if (squeeze_notes (&head
, &end
))
3275 reorder_insns (head
, end
, PREV_INSN (earliest
));
3278 /* Remove the jump and edge if we can. */
3279 if (other_bb
== new_dest
)
3282 remove_edge (BRANCH_EDGE (test_bb
));
3283 /* ??? Can't merge blocks here, as then_bb is still in use.
3284 At minimum, the merge will get done just before bb-reorder. */
3294 /* Main entry point for all if-conversion. */
3297 if_convert (int x_life_data_ok
)
3302 num_possible_if_blocks
= 0;
3303 num_updated_if_blocks
= 0;
3304 num_true_changes
= 0;
3305 life_data_ok
= (x_life_data_ok
!= 0);
3307 if ((! targetm
.cannot_modify_jumps_p ())
3308 && (!flag_reorder_blocks_and_partition
|| !no_new_pseudos
3309 || !targetm
.have_named_sections
))
3310 mark_loop_exit_edges ();
3312 /* Compute postdominators if we think we'll use them. */
3313 if (HAVE_conditional_execution
|| life_data_ok
)
3314 calculate_dominance_info (CDI_POST_DOMINATORS
);
3319 /* Go through each of the basic blocks looking for things to convert. If we
3320 have conditional execution, we make multiple passes to allow us to handle
3321 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3325 cond_exec_changed_p
= FALSE
;
3328 #ifdef IFCVT_MULTIPLE_DUMPS
3329 if (dump_file
&& pass
> 1)
3330 fprintf (dump_file
, "\n\n========== Pass %d ==========\n", pass
);
3336 while ((new_bb
= find_if_header (bb
, pass
)))
3340 #ifdef IFCVT_MULTIPLE_DUMPS
3341 if (dump_file
&& cond_exec_changed_p
)
3342 print_rtl_with_bb (dump_file
, get_insns ());
3345 while (cond_exec_changed_p
);
3347 #ifdef IFCVT_MULTIPLE_DUMPS
3349 fprintf (dump_file
, "\n\n========== no more changes\n");
3352 free_dominance_info (CDI_POST_DOMINATORS
);
3357 clear_aux_for_blocks ();
3359 /* Rebuild life info for basic blocks that require it. */
3360 if (num_true_changes
&& life_data_ok
)
3362 /* If we allocated new pseudos, we must resize the array for sched1. */
3363 if (max_regno
< max_reg_num ())
3365 max_regno
= max_reg_num ();
3366 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3368 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES
,
3369 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
3370 | PROP_KILL_DEAD_CODE
);
3373 /* Write the final stats. */
3374 if (dump_file
&& num_possible_if_blocks
> 0)
3377 "\n%d possible IF blocks searched.\n",
3378 num_possible_if_blocks
);
3380 "%d IF blocks converted.\n",
3381 num_updated_if_blocks
);
3383 "%d true changes made.\n\n\n",
3387 #ifdef ENABLE_CHECKING
3388 verify_flow_info ();