1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 #include "coretypes.h"
30 #include "insn-config.h"
33 #include "hard-reg-set.h"
34 #include "basic-block.h"
45 #ifndef HAVE_conditional_execution
46 #define HAVE_conditional_execution 0
48 #ifndef HAVE_conditional_move
49 #define HAVE_conditional_move 0
60 #ifndef HAVE_conditional_trap
61 #define HAVE_conditional_trap 0
64 #ifndef MAX_CONDITIONAL_EXECUTE
65 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
68 #define NULL_EDGE ((struct edge_def *)NULL)
69 #define NULL_BLOCK ((struct basic_block_def *)NULL)
71 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
72 static int num_possible_if_blocks
;
74 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
76 static int num_updated_if_blocks
;
78 /* # of changes made which require life information to be updated. */
79 static int num_true_changes
;
81 /* Whether conditional execution changes were made. */
82 static int cond_exec_changed_p
;
84 /* True if life data ok at present. */
85 static bool life_data_ok
;
87 /* Forward references. */
88 static int count_bb_insns (basic_block
);
89 static rtx
first_active_insn (basic_block
);
90 static rtx
last_active_insn (basic_block
, int);
91 static basic_block
block_fallthru (basic_block
);
92 static int cond_exec_process_insns (ce_if_block_t
*, rtx
, rtx
, rtx
, rtx
, int);
93 static rtx
cond_exec_get_condition (rtx
);
94 static int cond_exec_process_if_block (ce_if_block_t
*, int);
95 static rtx
noce_get_condition (rtx
, rtx
*);
96 static int noce_operand_ok (rtx
);
97 static int noce_process_if_block (ce_if_block_t
*);
98 static int process_if_block (ce_if_block_t
*);
99 static void merge_if_block (ce_if_block_t
*);
100 static int find_cond_trap (basic_block
, edge
, edge
);
101 static basic_block
find_if_header (basic_block
, int);
102 static int block_jumps_and_fallthru_p (basic_block
, basic_block
);
103 static int find_if_block (ce_if_block_t
*);
104 static int find_if_case_1 (basic_block
, edge
, edge
);
105 static int find_if_case_2 (basic_block
, edge
, edge
);
106 static int find_memory (rtx
*, void *);
107 static int dead_or_predicable (basic_block
, basic_block
, basic_block
,
109 static void noce_emit_move_insn (rtx
, rtx
);
110 static rtx
block_has_only_trap (basic_block
);
111 static void mark_loop_exit_edges (void);
113 /* Sets EDGE_LOOP_EXIT flag for all loop exits. */
115 mark_loop_exit_edges (void)
121 flow_loops_find (&loops
, LOOP_TREE
);
122 free_dominance_info (CDI_DOMINATORS
);
128 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
130 if (find_common_loop (bb
->loop_father
, e
->dest
->loop_father
)
132 e
->flags
|= EDGE_LOOP_EXIT
;
134 e
->flags
&= ~EDGE_LOOP_EXIT
;
139 flow_loops_free (&loops
);
142 /* Count the number of non-jump active insns in BB. */
145 count_bb_insns (basic_block bb
)
148 rtx insn
= BB_HEAD (bb
);
152 if (GET_CODE (insn
) == CALL_INSN
|| GET_CODE (insn
) == INSN
)
155 if (insn
== BB_END (bb
))
157 insn
= NEXT_INSN (insn
);
163 /* Return the first non-jump active insn in the basic block. */
166 first_active_insn (basic_block bb
)
168 rtx insn
= BB_HEAD (bb
);
170 if (GET_CODE (insn
) == CODE_LABEL
)
172 if (insn
== BB_END (bb
))
174 insn
= NEXT_INSN (insn
);
177 while (GET_CODE (insn
) == NOTE
)
179 if (insn
== BB_END (bb
))
181 insn
= NEXT_INSN (insn
);
184 if (GET_CODE (insn
) == JUMP_INSN
)
190 /* Return the last non-jump active (non-jump) insn in the basic block. */
193 last_active_insn (basic_block bb
, int skip_use_p
)
195 rtx insn
= BB_END (bb
);
196 rtx head
= BB_HEAD (bb
);
198 while (GET_CODE (insn
) == NOTE
199 || GET_CODE (insn
) == JUMP_INSN
201 && GET_CODE (insn
) == INSN
202 && GET_CODE (PATTERN (insn
)) == USE
))
206 insn
= PREV_INSN (insn
);
209 if (GET_CODE (insn
) == CODE_LABEL
)
215 /* Return the basic block reached by falling though the basic block BB. */
218 block_fallthru (basic_block bb
)
223 e
!= NULL_EDGE
&& (e
->flags
& EDGE_FALLTHRU
) == 0;
227 return (e
) ? e
->dest
: NULL_BLOCK
;
230 /* Go through a bunch of insns, converting them to conditional
231 execution format if possible. Return TRUE if all of the non-note
232 insns were processed. */
235 cond_exec_process_insns (ce_if_block_t
*ce_info ATTRIBUTE_UNUSED
,
236 /* if block information */rtx start
,
237 /* first insn to look at */rtx end
,
238 /* last insn to look at */rtx test
,
239 /* conditional execution test */rtx prob_val
,
240 /* probability of branch taken. */int mod_ok
)
242 int must_be_last
= FALSE
;
250 for (insn
= start
; ; insn
= NEXT_INSN (insn
))
252 if (GET_CODE (insn
) == NOTE
)
255 if (GET_CODE (insn
) != INSN
&& GET_CODE (insn
) != CALL_INSN
)
258 /* Remove USE insns that get in the way. */
259 if (reload_completed
&& GET_CODE (PATTERN (insn
)) == USE
)
261 /* ??? Ug. Actually unlinking the thing is problematic,
262 given what we'd have to coordinate with our callers. */
263 SET_INSN_DELETED (insn
);
267 /* Last insn wasn't last? */
271 if (modified_in_p (test
, insn
))
278 /* Now build the conditional form of the instruction. */
279 pattern
= PATTERN (insn
);
280 xtest
= copy_rtx (test
);
282 /* If this is already a COND_EXEC, rewrite the test to be an AND of the
284 if (GET_CODE (pattern
) == COND_EXEC
)
286 if (GET_MODE (xtest
) != GET_MODE (COND_EXEC_TEST (pattern
)))
289 xtest
= gen_rtx_AND (GET_MODE (xtest
), xtest
,
290 COND_EXEC_TEST (pattern
));
291 pattern
= COND_EXEC_CODE (pattern
);
294 pattern
= gen_rtx_COND_EXEC (VOIDmode
, xtest
, pattern
);
296 /* If the machine needs to modify the insn being conditionally executed,
297 say for example to force a constant integer operand into a temp
298 register, do so here. */
299 #ifdef IFCVT_MODIFY_INSN
300 IFCVT_MODIFY_INSN (ce_info
, pattern
, insn
);
305 validate_change (insn
, &PATTERN (insn
), pattern
, 1);
307 if (GET_CODE (insn
) == CALL_INSN
&& prob_val
)
308 validate_change (insn
, ®_NOTES (insn
),
309 alloc_EXPR_LIST (REG_BR_PROB
, prob_val
,
310 REG_NOTES (insn
)), 1);
320 /* Return the condition for a jump. Do not do any special processing. */
323 cond_exec_get_condition (rtx jump
)
327 if (any_condjump_p (jump
))
328 test_if
= SET_SRC (pc_set (jump
));
331 cond
= XEXP (test_if
, 0);
333 /* If this branches to JUMP_LABEL when the condition is false,
334 reverse the condition. */
335 if (GET_CODE (XEXP (test_if
, 2)) == LABEL_REF
336 && XEXP (XEXP (test_if
, 2), 0) == JUMP_LABEL (jump
))
338 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
342 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
349 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
350 to conditional execution. Return TRUE if we were successful at
351 converting the block. */
354 cond_exec_process_if_block (ce_if_block_t
* ce_info
,
355 /* if block information */int do_multiple_p
)
357 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
358 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
359 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
360 rtx test_expr
; /* expression in IF_THEN_ELSE that is tested */
361 rtx then_start
; /* first insn in THEN block */
362 rtx then_end
; /* last insn + 1 in THEN block */
363 rtx else_start
= NULL_RTX
; /* first insn in ELSE block or NULL */
364 rtx else_end
= NULL_RTX
; /* last insn + 1 in ELSE block */
365 int max
; /* max # of insns to convert. */
366 int then_mod_ok
; /* whether conditional mods are ok in THEN */
367 rtx true_expr
; /* test for else block insns */
368 rtx false_expr
; /* test for then block insns */
369 rtx true_prob_val
; /* probability of else block */
370 rtx false_prob_val
; /* probability of then block */
372 enum rtx_code false_code
;
374 /* If test is comprised of && or || elements, and we've failed at handling
375 all of them together, just use the last test if it is the special case of
376 && elements without an ELSE block. */
377 if (!do_multiple_p
&& ce_info
->num_multiple_test_blocks
)
379 if (else_bb
|| ! ce_info
->and_and_p
)
382 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
383 ce_info
->num_multiple_test_blocks
= 0;
384 ce_info
->num_and_and_blocks
= 0;
385 ce_info
->num_or_or_blocks
= 0;
388 /* Find the conditional jump to the ELSE or JOIN part, and isolate
390 test_expr
= cond_exec_get_condition (BB_END (test_bb
));
394 /* If the conditional jump is more than just a conditional jump,
395 then we can not do conditional execution conversion on this block. */
396 if (! onlyjump_p (BB_END (test_bb
)))
399 /* Collect the bounds of where we're to search, skipping any labels, jumps
400 and notes at the beginning and end of the block. Then count the total
401 number of insns and see if it is small enough to convert. */
402 then_start
= first_active_insn (then_bb
);
403 then_end
= last_active_insn (then_bb
, TRUE
);
404 n_insns
= ce_info
->num_then_insns
= count_bb_insns (then_bb
);
405 max
= MAX_CONDITIONAL_EXECUTE
;
410 else_start
= first_active_insn (else_bb
);
411 else_end
= last_active_insn (else_bb
, TRUE
);
412 n_insns
+= ce_info
->num_else_insns
= count_bb_insns (else_bb
);
418 /* Map test_expr/test_jump into the appropriate MD tests to use on
419 the conditionally executed code. */
421 true_expr
= test_expr
;
423 false_code
= reversed_comparison_code (true_expr
, BB_END (test_bb
));
424 if (false_code
!= UNKNOWN
)
425 false_expr
= gen_rtx_fmt_ee (false_code
, GET_MODE (true_expr
),
426 XEXP (true_expr
, 0), XEXP (true_expr
, 1));
428 false_expr
= NULL_RTX
;
430 #ifdef IFCVT_MODIFY_TESTS
431 /* If the machine description needs to modify the tests, such as setting a
432 conditional execution register from a comparison, it can do so here. */
433 IFCVT_MODIFY_TESTS (ce_info
, true_expr
, false_expr
);
435 /* See if the conversion failed. */
436 if (!true_expr
|| !false_expr
)
440 true_prob_val
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
443 true_prob_val
= XEXP (true_prob_val
, 0);
444 false_prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (true_prob_val
));
447 false_prob_val
= NULL_RTX
;
449 /* If we have && or || tests, do them here. These tests are in the adjacent
450 blocks after the first block containing the test. */
451 if (ce_info
->num_multiple_test_blocks
> 0)
453 basic_block bb
= test_bb
;
454 basic_block last_test_bb
= ce_info
->last_test_bb
;
464 bb
= block_fallthru (bb
);
465 start
= first_active_insn (bb
);
466 end
= last_active_insn (bb
, TRUE
);
468 && ! cond_exec_process_insns (ce_info
, start
, end
, false_expr
,
469 false_prob_val
, FALSE
))
472 /* If the conditional jump is more than just a conditional jump, then
473 we can not do conditional execution conversion on this block. */
474 if (! onlyjump_p (BB_END (bb
)))
477 /* Find the conditional jump and isolate the test. */
478 t
= cond_exec_get_condition (BB_END (bb
));
482 f
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (t
)),
487 if (ce_info
->and_and_p
)
489 t
= gen_rtx_AND (GET_MODE (t
), true_expr
, t
);
490 f
= gen_rtx_IOR (GET_MODE (t
), false_expr
, f
);
494 t
= gen_rtx_IOR (GET_MODE (t
), true_expr
, t
);
495 f
= gen_rtx_AND (GET_MODE (t
), false_expr
, f
);
498 /* If the machine description needs to modify the tests, such as
499 setting a conditional execution register from a comparison, it can
501 #ifdef IFCVT_MODIFY_MULTIPLE_TESTS
502 IFCVT_MODIFY_MULTIPLE_TESTS (ce_info
, bb
, t
, f
);
504 /* See if the conversion failed. */
512 while (bb
!= last_test_bb
);
515 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
516 on then THEN block. */
517 then_mod_ok
= (else_bb
== NULL_BLOCK
);
519 /* Go through the THEN and ELSE blocks converting the insns if possible
520 to conditional execution. */
524 || ! cond_exec_process_insns (ce_info
, then_start
, then_end
,
525 false_expr
, false_prob_val
,
529 if (else_bb
&& else_end
530 && ! cond_exec_process_insns (ce_info
, else_start
, else_end
,
531 true_expr
, true_prob_val
, TRUE
))
534 /* If we cannot apply the changes, fail. Do not go through the normal fail
535 processing, since apply_change_group will call cancel_changes. */
536 if (! apply_change_group ())
538 #ifdef IFCVT_MODIFY_CANCEL
539 /* Cancel any machine dependent changes. */
540 IFCVT_MODIFY_CANCEL (ce_info
);
545 #ifdef IFCVT_MODIFY_FINAL
546 /* Do any machine dependent final modifications. */
547 IFCVT_MODIFY_FINAL (ce_info
);
550 /* Conversion succeeded. */
552 fprintf (dump_file
, "%d insn%s converted to conditional execution.\n",
553 n_insns
, (n_insns
== 1) ? " was" : "s were");
555 /* Merge the blocks! */
556 merge_if_block (ce_info
);
557 cond_exec_changed_p
= TRUE
;
561 #ifdef IFCVT_MODIFY_CANCEL
562 /* Cancel any machine dependent changes. */
563 IFCVT_MODIFY_CANCEL (ce_info
);
570 /* Used by noce_process_if_block to communicate with its subroutines.
572 The subroutines know that A and B may be evaluated freely. They
573 know that X is a register. They should insert new instructions
574 before cond_earliest. */
581 rtx jump
, cond
, cond_earliest
;
582 /* True if "b" was originally evaluated unconditionally. */
583 bool b_unconditional
;
586 static rtx
noce_emit_store_flag (struct noce_if_info
*, rtx
, int, int);
587 static int noce_try_move (struct noce_if_info
*);
588 static int noce_try_store_flag (struct noce_if_info
*);
589 static int noce_try_addcc (struct noce_if_info
*);
590 static int noce_try_store_flag_constants (struct noce_if_info
*);
591 static int noce_try_store_flag_mask (struct noce_if_info
*);
592 static rtx
noce_emit_cmove (struct noce_if_info
*, rtx
, enum rtx_code
, rtx
,
594 static int noce_try_cmove (struct noce_if_info
*);
595 static int noce_try_cmove_arith (struct noce_if_info
*);
596 static rtx
noce_get_alt_condition (struct noce_if_info
*, rtx
, rtx
*);
597 static int noce_try_minmax (struct noce_if_info
*);
598 static int noce_try_abs (struct noce_if_info
*);
599 static int noce_try_sign_mask (struct noce_if_info
*);
601 /* Helper function for noce_try_store_flag*. */
604 noce_emit_store_flag (struct noce_if_info
*if_info
, rtx x
, int reversep
,
607 rtx cond
= if_info
->cond
;
611 cond_complex
= (! general_operand (XEXP (cond
, 0), VOIDmode
)
612 || ! general_operand (XEXP (cond
, 1), VOIDmode
));
614 /* If earliest == jump, or when the condition is complex, try to
615 build the store_flag insn directly. */
618 cond
= XEXP (SET_SRC (pc_set (if_info
->jump
)), 0);
621 code
= reversed_comparison_code (cond
, if_info
->jump
);
623 code
= GET_CODE (cond
);
625 if ((if_info
->cond_earliest
== if_info
->jump
|| cond_complex
)
626 && (normalize
== 0 || STORE_FLAG_VALUE
== normalize
))
630 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (x
), XEXP (cond
, 0),
632 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
635 tmp
= emit_insn (tmp
);
637 if (recog_memoized (tmp
) >= 0)
643 if_info
->cond_earliest
= if_info
->jump
;
651 /* Don't even try if the comparison operands or the mode of X are weird. */
652 if (cond_complex
|| !SCALAR_INT_MODE_P (GET_MODE (x
)))
655 return emit_store_flag (x
, code
, XEXP (cond
, 0),
656 XEXP (cond
, 1), VOIDmode
,
657 (code
== LTU
|| code
== LEU
658 || code
== GEU
|| code
== GTU
), normalize
);
661 /* Emit instruction to move an rtx, possibly into STRICT_LOW_PART.
662 X is the destination/target and Y is the value to copy. */
665 noce_emit_move_insn (rtx x
, rtx y
)
667 enum machine_mode outmode
, inmode
;
671 if (GET_CODE (x
) != STRICT_LOW_PART
)
673 emit_move_insn (x
, y
);
678 inner
= XEXP (outer
, 0);
679 outmode
= GET_MODE (outer
);
680 inmode
= GET_MODE (inner
);
681 bitpos
= SUBREG_BYTE (outer
) * BITS_PER_UNIT
;
682 store_bit_field (inner
, GET_MODE_BITSIZE (outmode
), bitpos
, outmode
, y
,
683 GET_MODE_BITSIZE (inmode
));
686 /* Return sequence of instructions generated by if conversion. This
687 function calls end_sequence() to end the current stream, ensures
688 that are instructions are unshared, recognizable non-jump insns.
689 On failure, this function returns a NULL_RTX. */
692 end_ifcvt_sequence (struct noce_if_info
*if_info
)
695 rtx seq
= get_insns ();
697 set_used_flags (if_info
->x
);
698 set_used_flags (if_info
->cond
);
699 unshare_all_rtl_in_chain (seq
);
702 /* Make sure that all of the instructions emitted are recognizable,
703 and that we haven't introduced a new jump instruction.
704 As an exercise for the reader, build a general mechanism that
705 allows proper placement of required clobbers. */
706 for (insn
= seq
; insn
; insn
= NEXT_INSN (insn
))
707 if (GET_CODE (insn
) == JUMP_INSN
708 || recog_memoized (insn
) == -1)
714 /* Convert "if (a != b) x = a; else x = b" into "x = a" and
715 "if (a == b) x = a; else x = b" into "x = b". */
718 noce_try_move (struct noce_if_info
*if_info
)
720 rtx cond
= if_info
->cond
;
721 enum rtx_code code
= GET_CODE (cond
);
724 if (code
!= NE
&& code
!= EQ
)
727 /* This optimization isn't valid if either A or B could be a NaN
729 if (HONOR_NANS (GET_MODE (if_info
->x
))
730 || HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
)))
733 /* Check whether the operands of the comparison are A and in
735 if ((rtx_equal_p (if_info
->a
, XEXP (cond
, 0))
736 && rtx_equal_p (if_info
->b
, XEXP (cond
, 1)))
737 || (rtx_equal_p (if_info
->a
, XEXP (cond
, 1))
738 && rtx_equal_p (if_info
->b
, XEXP (cond
, 0))))
740 y
= (code
== EQ
) ? if_info
->a
: if_info
->b
;
742 /* Avoid generating the move if the source is the destination. */
743 if (! rtx_equal_p (if_info
->x
, y
))
746 noce_emit_move_insn (if_info
->x
, y
);
747 seq
= end_ifcvt_sequence (if_info
);
751 emit_insn_before_setloc (seq
, if_info
->jump
,
752 INSN_LOCATOR (if_info
->insn_a
));
759 /* Convert "if (test) x = 1; else x = 0".
761 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
762 tried in noce_try_store_flag_constants after noce_try_cmove has had
763 a go at the conversion. */
766 noce_try_store_flag (struct noce_if_info
*if_info
)
771 if (GET_CODE (if_info
->b
) == CONST_INT
772 && INTVAL (if_info
->b
) == STORE_FLAG_VALUE
773 && if_info
->a
== const0_rtx
)
775 else if (if_info
->b
== const0_rtx
776 && GET_CODE (if_info
->a
) == CONST_INT
777 && INTVAL (if_info
->a
) == STORE_FLAG_VALUE
778 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
786 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, 0);
789 if (target
!= if_info
->x
)
790 noce_emit_move_insn (if_info
->x
, target
);
792 seq
= end_ifcvt_sequence (if_info
);
796 emit_insn_before_setloc (seq
, if_info
->jump
,
797 INSN_LOCATOR (if_info
->insn_a
));
807 /* Convert "if (test) x = a; else x = b", for A and B constant. */
810 noce_try_store_flag_constants (struct noce_if_info
*if_info
)
814 HOST_WIDE_INT itrue
, ifalse
, diff
, tmp
;
815 int normalize
, can_reverse
;
816 enum machine_mode mode
;
819 && GET_CODE (if_info
->a
) == CONST_INT
820 && GET_CODE (if_info
->b
) == CONST_INT
)
822 mode
= GET_MODE (if_info
->x
);
823 ifalse
= INTVAL (if_info
->a
);
824 itrue
= INTVAL (if_info
->b
);
826 /* Make sure we can represent the difference between the two values. */
827 if ((itrue
- ifalse
> 0)
828 != ((ifalse
< 0) != (itrue
< 0) ? ifalse
< 0 : ifalse
< itrue
))
831 diff
= trunc_int_for_mode (itrue
- ifalse
, mode
);
833 can_reverse
= (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
837 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
839 else if (ifalse
== 0 && exact_log2 (itrue
) >= 0
840 && (STORE_FLAG_VALUE
== 1
841 || BRANCH_COST
>= 2))
843 else if (itrue
== 0 && exact_log2 (ifalse
) >= 0 && can_reverse
844 && (STORE_FLAG_VALUE
== 1 || BRANCH_COST
>= 2))
845 normalize
= 1, reversep
= 1;
847 && (STORE_FLAG_VALUE
== -1
848 || BRANCH_COST
>= 2))
850 else if (ifalse
== -1 && can_reverse
851 && (STORE_FLAG_VALUE
== -1 || BRANCH_COST
>= 2))
852 normalize
= -1, reversep
= 1;
853 else if ((BRANCH_COST
>= 2 && STORE_FLAG_VALUE
== -1)
861 tmp
= itrue
; itrue
= ifalse
; ifalse
= tmp
;
862 diff
= trunc_int_for_mode (-diff
, mode
);
866 target
= noce_emit_store_flag (if_info
, if_info
->x
, reversep
, normalize
);
873 /* if (test) x = 3; else x = 4;
874 => x = 3 + (test == 0); */
875 if (diff
== STORE_FLAG_VALUE
|| diff
== -STORE_FLAG_VALUE
)
877 target
= expand_simple_binop (mode
,
878 (diff
== STORE_FLAG_VALUE
880 GEN_INT (ifalse
), target
, if_info
->x
, 0,
884 /* if (test) x = 8; else x = 0;
885 => x = (test != 0) << 3; */
886 else if (ifalse
== 0 && (tmp
= exact_log2 (itrue
)) >= 0)
888 target
= expand_simple_binop (mode
, ASHIFT
,
889 target
, GEN_INT (tmp
), if_info
->x
, 0,
893 /* if (test) x = -1; else x = b;
894 => x = -(test != 0) | b; */
895 else if (itrue
== -1)
897 target
= expand_simple_binop (mode
, IOR
,
898 target
, GEN_INT (ifalse
), if_info
->x
, 0,
902 /* if (test) x = a; else x = b;
903 => x = (-(test != 0) & (b - a)) + a; */
906 target
= expand_simple_binop (mode
, AND
,
907 target
, GEN_INT (diff
), if_info
->x
, 0,
910 target
= expand_simple_binop (mode
, PLUS
,
911 target
, GEN_INT (ifalse
),
912 if_info
->x
, 0, OPTAB_WIDEN
);
921 if (target
!= if_info
->x
)
922 noce_emit_move_insn (if_info
->x
, target
);
924 seq
= end_ifcvt_sequence (if_info
);
928 emit_insn_before_setloc (seq
, if_info
->jump
,
929 INSN_LOCATOR (if_info
->insn_a
));
936 /* Convert "if (test) foo++" into "foo += (test != 0)", and
937 similarly for "foo--". */
940 noce_try_addcc (struct noce_if_info
*if_info
)
943 int subtract
, normalize
;
946 && GET_CODE (if_info
->a
) == PLUS
947 && rtx_equal_p (XEXP (if_info
->a
, 0), if_info
->b
)
948 && (reversed_comparison_code (if_info
->cond
, if_info
->jump
)
951 rtx cond
= if_info
->cond
;
952 enum rtx_code code
= reversed_comparison_code (cond
, if_info
->jump
);
954 /* First try to use addcc pattern. */
955 if (general_operand (XEXP (cond
, 0), VOIDmode
)
956 && general_operand (XEXP (cond
, 1), VOIDmode
))
959 target
= emit_conditional_add (if_info
->x
, code
,
964 XEXP (if_info
->a
, 1),
965 GET_MODE (if_info
->x
),
966 (code
== LTU
|| code
== GEU
967 || code
== LEU
|| code
== GTU
));
970 if (target
!= if_info
->x
)
971 noce_emit_move_insn (if_info
->x
, target
);
973 seq
= end_ifcvt_sequence (if_info
);
977 emit_insn_before_setloc (seq
, if_info
->jump
,
978 INSN_LOCATOR (if_info
->insn_a
));
984 /* If that fails, construct conditional increment or decrement using
987 && (XEXP (if_info
->a
, 1) == const1_rtx
988 || XEXP (if_info
->a
, 1) == constm1_rtx
))
991 if (STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
992 subtract
= 0, normalize
= 0;
993 else if (-STORE_FLAG_VALUE
== INTVAL (XEXP (if_info
->a
, 1)))
994 subtract
= 1, normalize
= 0;
996 subtract
= 0, normalize
= INTVAL (XEXP (if_info
->a
, 1));
999 target
= noce_emit_store_flag (if_info
,
1000 gen_reg_rtx (GET_MODE (if_info
->x
)),
1004 target
= expand_simple_binop (GET_MODE (if_info
->x
),
1005 subtract
? MINUS
: PLUS
,
1006 if_info
->b
, target
, if_info
->x
,
1010 if (target
!= if_info
->x
)
1011 noce_emit_move_insn (if_info
->x
, target
);
1013 seq
= end_ifcvt_sequence (if_info
);
1017 emit_insn_before_setloc (seq
, if_info
->jump
,
1018 INSN_LOCATOR (if_info
->insn_a
));
1028 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
1031 noce_try_store_flag_mask (struct noce_if_info
*if_info
)
1037 if (! no_new_pseudos
1038 && (BRANCH_COST
>= 2
1039 || STORE_FLAG_VALUE
== -1)
1040 && ((if_info
->a
== const0_rtx
1041 && rtx_equal_p (if_info
->b
, if_info
->x
))
1042 || ((reversep
= (reversed_comparison_code (if_info
->cond
,
1045 && if_info
->b
== const0_rtx
1046 && rtx_equal_p (if_info
->a
, if_info
->x
))))
1049 target
= noce_emit_store_flag (if_info
,
1050 gen_reg_rtx (GET_MODE (if_info
->x
)),
1053 target
= expand_simple_binop (GET_MODE (if_info
->x
), AND
,
1055 target
, if_info
->x
, 0,
1060 if (target
!= if_info
->x
)
1061 noce_emit_move_insn (if_info
->x
, target
);
1063 seq
= end_ifcvt_sequence (if_info
);
1067 emit_insn_before_setloc (seq
, if_info
->jump
,
1068 INSN_LOCATOR (if_info
->insn_a
));
1078 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
1081 noce_emit_cmove (struct noce_if_info
*if_info
, rtx x
, enum rtx_code code
,
1082 rtx cmp_a
, rtx cmp_b
, rtx vfalse
, rtx vtrue
)
1084 /* If earliest == jump, try to build the cmove insn directly.
1085 This is helpful when combine has created some complex condition
1086 (like for alpha's cmovlbs) that we can't hope to regenerate
1087 through the normal interface. */
1089 if (if_info
->cond_earliest
== if_info
->jump
)
1093 tmp
= gen_rtx_fmt_ee (code
, GET_MODE (if_info
->cond
), cmp_a
, cmp_b
);
1094 tmp
= gen_rtx_IF_THEN_ELSE (GET_MODE (x
), tmp
, vtrue
, vfalse
);
1095 tmp
= gen_rtx_SET (VOIDmode
, x
, tmp
);
1098 tmp
= emit_insn (tmp
);
1100 if (recog_memoized (tmp
) >= 0)
1112 /* Don't even try if the comparison operands are weird. */
1113 if (! general_operand (cmp_a
, GET_MODE (cmp_a
))
1114 || ! general_operand (cmp_b
, GET_MODE (cmp_b
)))
1117 #if HAVE_conditional_move
1118 return emit_conditional_move (x
, code
, cmp_a
, cmp_b
, VOIDmode
,
1119 vtrue
, vfalse
, GET_MODE (x
),
1120 (code
== LTU
|| code
== GEU
1121 || code
== LEU
|| code
== GTU
));
1123 /* We'll never get here, as noce_process_if_block doesn't call the
1124 functions involved. Ifdef code, however, should be discouraged
1125 because it leads to typos in the code not selected. However,
1126 emit_conditional_move won't exist either. */
1131 /* Try only simple constants and registers here. More complex cases
1132 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
1133 has had a go at it. */
1136 noce_try_cmove (struct noce_if_info
*if_info
)
1141 if ((CONSTANT_P (if_info
->a
) || register_operand (if_info
->a
, VOIDmode
))
1142 && (CONSTANT_P (if_info
->b
) || register_operand (if_info
->b
, VOIDmode
)))
1146 code
= GET_CODE (if_info
->cond
);
1147 target
= noce_emit_cmove (if_info
, if_info
->x
, code
,
1148 XEXP (if_info
->cond
, 0),
1149 XEXP (if_info
->cond
, 1),
1150 if_info
->a
, if_info
->b
);
1154 if (target
!= if_info
->x
)
1155 noce_emit_move_insn (if_info
->x
, target
);
1157 seq
= end_ifcvt_sequence (if_info
);
1161 emit_insn_before_setloc (seq
, if_info
->jump
,
1162 INSN_LOCATOR (if_info
->insn_a
));
1175 /* Try more complex cases involving conditional_move. */
1178 noce_try_cmove_arith (struct noce_if_info
*if_info
)
1188 /* A conditional move from two memory sources is equivalent to a
1189 conditional on their addresses followed by a load. Don't do this
1190 early because it'll screw alias analysis. Note that we've
1191 already checked for no side effects. */
1192 if (! no_new_pseudos
&& cse_not_expected
1193 && MEM_P (a
) && MEM_P (b
)
1194 && BRANCH_COST
>= 5)
1198 x
= gen_reg_rtx (Pmode
);
1202 /* ??? We could handle this if we knew that a load from A or B could
1203 not fault. This is also true if we've already loaded
1204 from the address along the path from ENTRY. */
1205 else if (may_trap_p (a
) || may_trap_p (b
))
1208 /* if (test) x = a + b; else x = c - d;
1215 code
= GET_CODE (if_info
->cond
);
1216 insn_a
= if_info
->insn_a
;
1217 insn_b
= if_info
->insn_b
;
1219 /* Possibly rearrange operands to make things come out more natural. */
1220 if (reversed_comparison_code (if_info
->cond
, if_info
->jump
) != UNKNOWN
)
1223 if (rtx_equal_p (b
, x
))
1225 else if (general_operand (b
, GET_MODE (b
)))
1230 code
= reversed_comparison_code (if_info
->cond
, if_info
->jump
);
1231 tmp
= a
, a
= b
, b
= tmp
;
1232 tmp
= insn_a
, insn_a
= insn_b
, insn_b
= tmp
;
1238 /* If either operand is complex, load it into a register first.
1239 The best way to do this is to copy the original insn. In this
1240 way we preserve any clobbers etc that the insn may have had.
1241 This is of course not possible in the IS_MEM case. */
1242 if (! general_operand (a
, GET_MODE (a
)))
1247 goto end_seq_and_fail
;
1251 tmp
= gen_reg_rtx (GET_MODE (a
));
1252 tmp
= emit_insn (gen_rtx_SET (VOIDmode
, tmp
, a
));
1255 goto end_seq_and_fail
;
1258 a
= gen_reg_rtx (GET_MODE (a
));
1259 tmp
= copy_rtx (insn_a
);
1260 set
= single_set (tmp
);
1262 tmp
= emit_insn (PATTERN (tmp
));
1264 if (recog_memoized (tmp
) < 0)
1265 goto end_seq_and_fail
;
1267 if (! general_operand (b
, GET_MODE (b
)))
1272 goto end_seq_and_fail
;
1276 tmp
= gen_reg_rtx (GET_MODE (b
));
1277 tmp
= emit_insn (gen_rtx_SET (VOIDmode
,
1282 goto end_seq_and_fail
;
1285 b
= gen_reg_rtx (GET_MODE (b
));
1286 tmp
= copy_rtx (insn_b
);
1287 set
= single_set (tmp
);
1289 tmp
= emit_insn (PATTERN (tmp
));
1291 if (recog_memoized (tmp
) < 0)
1292 goto end_seq_and_fail
;
1295 target
= noce_emit_cmove (if_info
, x
, code
, XEXP (if_info
->cond
, 0),
1296 XEXP (if_info
->cond
, 1), a
, b
);
1299 goto end_seq_and_fail
;
1301 /* If we're handling a memory for above, emit the load now. */
1304 tmp
= gen_rtx_MEM (GET_MODE (if_info
->x
), target
);
1306 /* Copy over flags as appropriate. */
1307 if (MEM_VOLATILE_P (if_info
->a
) || MEM_VOLATILE_P (if_info
->b
))
1308 MEM_VOLATILE_P (tmp
) = 1;
1309 if (MEM_IN_STRUCT_P (if_info
->a
) && MEM_IN_STRUCT_P (if_info
->b
))
1310 MEM_IN_STRUCT_P (tmp
) = 1;
1311 if (MEM_SCALAR_P (if_info
->a
) && MEM_SCALAR_P (if_info
->b
))
1312 MEM_SCALAR_P (tmp
) = 1;
1313 if (MEM_ALIAS_SET (if_info
->a
) == MEM_ALIAS_SET (if_info
->b
))
1314 set_mem_alias_set (tmp
, MEM_ALIAS_SET (if_info
->a
));
1316 MIN (MEM_ALIGN (if_info
->a
), MEM_ALIGN (if_info
->b
)));
1318 noce_emit_move_insn (if_info
->x
, tmp
);
1320 else if (target
!= x
)
1321 noce_emit_move_insn (x
, target
);
1323 tmp
= end_ifcvt_sequence (if_info
);
1327 emit_insn_before_setloc (tmp
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1335 /* For most cases, the simplified condition we found is the best
1336 choice, but this is not the case for the min/max/abs transforms.
1337 For these we wish to know that it is A or B in the condition. */
1340 noce_get_alt_condition (struct noce_if_info
*if_info
, rtx target
,
1343 rtx cond
, set
, insn
;
1346 /* If target is already mentioned in the known condition, return it. */
1347 if (reg_mentioned_p (target
, if_info
->cond
))
1349 *earliest
= if_info
->cond_earliest
;
1350 return if_info
->cond
;
1353 set
= pc_set (if_info
->jump
);
1354 cond
= XEXP (SET_SRC (set
), 0);
1356 = GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1357 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (if_info
->jump
);
1359 /* If we're looking for a constant, try to make the conditional
1360 have that constant in it. There are two reasons why it may
1361 not have the constant we want:
1363 1. GCC may have needed to put the constant in a register, because
1364 the target can't compare directly against that constant. For
1365 this case, we look for a SET immediately before the comparison
1366 that puts a constant in that register.
1368 2. GCC may have canonicalized the conditional, for example
1369 replacing "if x < 4" with "if x <= 3". We can undo that (or
1370 make equivalent types of changes) to get the constants we need
1371 if they're off by one in the right direction. */
1373 if (GET_CODE (target
) == CONST_INT
)
1375 enum rtx_code code
= GET_CODE (if_info
->cond
);
1376 rtx op_a
= XEXP (if_info
->cond
, 0);
1377 rtx op_b
= XEXP (if_info
->cond
, 1);
1380 /* First, look to see if we put a constant in a register. */
1381 prev_insn
= PREV_INSN (if_info
->cond_earliest
);
1383 && INSN_P (prev_insn
)
1384 && GET_CODE (PATTERN (prev_insn
)) == SET
)
1386 rtx src
= find_reg_equal_equiv_note (prev_insn
);
1388 src
= SET_SRC (PATTERN (prev_insn
));
1389 if (GET_CODE (src
) == CONST_INT
)
1391 if (rtx_equal_p (op_a
, SET_DEST (PATTERN (prev_insn
))))
1393 else if (rtx_equal_p (op_b
, SET_DEST (PATTERN (prev_insn
))))
1396 if (GET_CODE (op_a
) == CONST_INT
)
1401 code
= swap_condition (code
);
1406 /* Now, look to see if we can get the right constant by
1407 adjusting the conditional. */
1408 if (GET_CODE (op_b
) == CONST_INT
)
1410 HOST_WIDE_INT desired_val
= INTVAL (target
);
1411 HOST_WIDE_INT actual_val
= INTVAL (op_b
);
1416 if (actual_val
== desired_val
+ 1)
1419 op_b
= GEN_INT (desired_val
);
1423 if (actual_val
== desired_val
- 1)
1426 op_b
= GEN_INT (desired_val
);
1430 if (actual_val
== desired_val
- 1)
1433 op_b
= GEN_INT (desired_val
);
1437 if (actual_val
== desired_val
+ 1)
1440 op_b
= GEN_INT (desired_val
);
1448 /* If we made any changes, generate a new conditional that is
1449 equivalent to what we started with, but has the right
1451 if (code
!= GET_CODE (if_info
->cond
)
1452 || op_a
!= XEXP (if_info
->cond
, 0)
1453 || op_b
!= XEXP (if_info
->cond
, 1))
1455 cond
= gen_rtx_fmt_ee (code
, GET_MODE (cond
), op_a
, op_b
);
1456 *earliest
= if_info
->cond_earliest
;
1461 cond
= canonicalize_condition (if_info
->jump
, cond
, reverse
,
1462 earliest
, target
, false);
1463 if (! cond
|| ! reg_mentioned_p (target
, cond
))
1466 /* We almost certainly searched back to a different place.
1467 Need to re-verify correct lifetimes. */
1469 /* X may not be mentioned in the range (cond_earliest, jump]. */
1470 for (insn
= if_info
->jump
; insn
!= *earliest
; insn
= PREV_INSN (insn
))
1471 if (INSN_P (insn
) && reg_overlap_mentioned_p (if_info
->x
, PATTERN (insn
)))
1474 /* A and B may not be modified in the range [cond_earliest, jump). */
1475 for (insn
= *earliest
; insn
!= if_info
->jump
; insn
= NEXT_INSN (insn
))
1477 && (modified_in_p (if_info
->a
, insn
)
1478 || modified_in_p (if_info
->b
, insn
)))
1484 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1487 noce_try_minmax (struct noce_if_info
*if_info
)
1489 rtx cond
, earliest
, target
, seq
;
1490 enum rtx_code code
, op
;
1493 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1497 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1498 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1499 to get the target to tell us... */
1500 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info
->x
))
1501 || HONOR_NANS (GET_MODE (if_info
->x
)))
1504 cond
= noce_get_alt_condition (if_info
, if_info
->a
, &earliest
);
1508 /* Verify the condition is of the form we expect, and canonicalize
1509 the comparison code. */
1510 code
= GET_CODE (cond
);
1511 if (rtx_equal_p (XEXP (cond
, 0), if_info
->a
))
1513 if (! rtx_equal_p (XEXP (cond
, 1), if_info
->b
))
1516 else if (rtx_equal_p (XEXP (cond
, 1), if_info
->a
))
1518 if (! rtx_equal_p (XEXP (cond
, 0), if_info
->b
))
1520 code
= swap_condition (code
);
1525 /* Determine what sort of operation this is. Note that the code is for
1526 a taken branch, so the code->operation mapping appears backwards. */
1559 target
= expand_simple_binop (GET_MODE (if_info
->x
), op
,
1560 if_info
->a
, if_info
->b
,
1561 if_info
->x
, unsignedp
, OPTAB_WIDEN
);
1567 if (target
!= if_info
->x
)
1568 noce_emit_move_insn (if_info
->x
, target
);
1570 seq
= end_ifcvt_sequence (if_info
);
1574 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1575 if_info
->cond
= cond
;
1576 if_info
->cond_earliest
= earliest
;
1581 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1584 noce_try_abs (struct noce_if_info
*if_info
)
1586 rtx cond
, earliest
, target
, seq
, a
, b
, c
;
1589 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1593 /* Recognize A and B as constituting an ABS or NABS. */
1596 if (GET_CODE (a
) == NEG
&& rtx_equal_p (XEXP (a
, 0), b
))
1598 else if (GET_CODE (b
) == NEG
&& rtx_equal_p (XEXP (b
, 0), a
))
1600 c
= a
; a
= b
; b
= c
;
1606 cond
= noce_get_alt_condition (if_info
, b
, &earliest
);
1610 /* Verify the condition is of the form we expect. */
1611 if (rtx_equal_p (XEXP (cond
, 0), b
))
1613 else if (rtx_equal_p (XEXP (cond
, 1), b
))
1618 /* Verify that C is zero. Search backward through the block for
1619 a REG_EQUAL note if necessary. */
1622 rtx insn
, note
= NULL
;
1623 for (insn
= earliest
;
1624 insn
!= BB_HEAD (if_info
->test_bb
);
1625 insn
= PREV_INSN (insn
))
1627 && ((note
= find_reg_note (insn
, REG_EQUAL
, c
))
1628 || (note
= find_reg_note (insn
, REG_EQUIV
, c
))))
1635 && GET_CODE (XEXP (c
, 0)) == SYMBOL_REF
1636 && CONSTANT_POOL_ADDRESS_P (XEXP (c
, 0)))
1637 c
= get_pool_constant (XEXP (c
, 0));
1639 /* Work around funny ideas get_condition has wrt canonicalization.
1640 Note that these rtx constants are known to be CONST_INT, and
1641 therefore imply integer comparisons. */
1642 if (c
== constm1_rtx
&& GET_CODE (cond
) == GT
)
1644 else if (c
== const1_rtx
&& GET_CODE (cond
) == LT
)
1646 else if (c
!= CONST0_RTX (GET_MODE (b
)))
1649 /* Determine what sort of operation this is. */
1650 switch (GET_CODE (cond
))
1669 target
= expand_abs_nojump (GET_MODE (if_info
->x
), b
, if_info
->x
, 1);
1671 /* ??? It's a quandary whether cmove would be better here, especially
1672 for integers. Perhaps combine will clean things up. */
1673 if (target
&& negate
)
1674 target
= expand_simple_unop (GET_MODE (target
), NEG
, target
, if_info
->x
, 0);
1682 if (target
!= if_info
->x
)
1683 noce_emit_move_insn (if_info
->x
, target
);
1685 seq
= end_ifcvt_sequence (if_info
);
1689 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1690 if_info
->cond
= cond
;
1691 if_info
->cond_earliest
= earliest
;
1696 /* Convert "if (m < 0) x = b; else x = 0;" to "x = (m >> C) & b;". */
1699 noce_try_sign_mask (struct noce_if_info
*if_info
)
1701 rtx cond
, t
, m
, c
, seq
;
1702 enum machine_mode mode
;
1708 cond
= if_info
->cond
;
1709 code
= GET_CODE (cond
);
1714 if (if_info
->a
== const0_rtx
)
1716 if ((code
== LT
&& c
== const0_rtx
)
1717 || (code
== LE
&& c
== constm1_rtx
))
1720 else if (if_info
->b
== const0_rtx
)
1722 if ((code
== GE
&& c
== const0_rtx
)
1723 || (code
== GT
&& c
== constm1_rtx
))
1727 if (! t
|| side_effects_p (t
))
1730 /* We currently don't handle different modes. */
1731 mode
= GET_MODE (t
);
1732 if (GET_MODE (m
) != mode
)
1735 /* This is only profitable if T is cheap, or T is unconditionally
1736 executed/evaluated in the original insn sequence. */
1737 if (rtx_cost (t
, SET
) >= COSTS_N_INSNS (2)
1738 && (!if_info
->b_unconditional
1739 || t
!= if_info
->b
))
1743 /* Use emit_store_flag to generate "m < 0 ? -1 : 0" instead of expanding
1744 "(signed) m >> 31" directly. This benefits targets with specialized
1745 insns to obtain the signmask, but still uses ashr_optab otherwise. */
1746 m
= emit_store_flag (gen_reg_rtx (mode
), LT
, m
, const0_rtx
, mode
, 0, -1);
1747 t
= m
? expand_binop (mode
, and_optab
, m
, t
, NULL_RTX
, 0, OPTAB_DIRECT
)
1756 noce_emit_move_insn (if_info
->x
, t
);
1758 seq
= end_ifcvt_sequence (if_info
);
1762 emit_insn_before_setloc (seq
, if_info
->jump
, INSN_LOCATOR (if_info
->insn_a
));
1767 /* Similar to get_condition, only the resulting condition must be
1768 valid at JUMP, instead of at EARLIEST. */
1771 noce_get_condition (rtx jump
, rtx
*earliest
)
1773 rtx cond
, set
, tmp
, insn
;
1776 if (! any_condjump_p (jump
))
1779 set
= pc_set (jump
);
1781 /* If this branches to JUMP_LABEL when the condition is false,
1782 reverse the condition. */
1783 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
1784 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
1786 /* If the condition variable is a register and is MODE_INT, accept it. */
1788 cond
= XEXP (SET_SRC (set
), 0);
1789 tmp
= XEXP (cond
, 0);
1790 if (REG_P (tmp
) && GET_MODE_CLASS (GET_MODE (tmp
)) == MODE_INT
)
1795 cond
= gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond
)),
1796 GET_MODE (cond
), tmp
, XEXP (cond
, 1));
1800 /* Otherwise, fall back on canonicalize_condition to do the dirty
1801 work of manipulating MODE_CC values and COMPARE rtx codes. */
1803 tmp
= canonicalize_condition (jump
, cond
, reverse
, earliest
, NULL_RTX
,
1808 /* We are going to insert code before JUMP, not before EARLIEST.
1809 We must therefore be certain that the given condition is valid
1810 at JUMP by virtue of not having been modified since. */
1811 for (insn
= *earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
1812 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
1817 /* The condition was modified. See if we can get a partial result
1818 that doesn't follow all the reversals. Perhaps combine can fold
1819 them together later. */
1820 tmp
= XEXP (tmp
, 0);
1821 if (!REG_P (tmp
) || GET_MODE_CLASS (GET_MODE (tmp
)) != MODE_INT
)
1823 tmp
= canonicalize_condition (jump
, cond
, reverse
, earliest
, tmp
,
1828 /* For sanity's sake, re-validate the new result. */
1829 for (insn
= *earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
1830 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
1836 /* Return true if OP is ok for if-then-else processing. */
1839 noce_operand_ok (rtx op
)
1841 /* We special-case memories, so handle any of them with
1842 no address side effects. */
1844 return ! side_effects_p (XEXP (op
, 0));
1846 if (side_effects_p (op
))
1849 return ! may_trap_p (op
);
1852 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1853 without using conditional execution. Return TRUE if we were
1854 successful at converting the block. */
1857 noce_process_if_block (struct ce_if_block
* ce_info
)
1859 basic_block test_bb
= ce_info
->test_bb
; /* test block */
1860 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
1861 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
1862 struct noce_if_info if_info
;
1865 rtx orig_x
, x
, a
, b
;
1868 /* We're looking for patterns of the form
1870 (1) if (...) x = a; else x = b;
1871 (2) x = b; if (...) x = a;
1872 (3) if (...) x = a; // as if with an initial x = x.
1874 The later patterns require jumps to be more expensive.
1876 ??? For future expansion, look for multiple X in such patterns. */
1878 /* If test is comprised of && or || elements, don't handle it unless it is
1879 the special case of && elements without an ELSE block. */
1880 if (ce_info
->num_multiple_test_blocks
)
1882 if (else_bb
|| ! ce_info
->and_and_p
)
1885 ce_info
->test_bb
= test_bb
= ce_info
->last_test_bb
;
1886 ce_info
->num_multiple_test_blocks
= 0;
1887 ce_info
->num_and_and_blocks
= 0;
1888 ce_info
->num_or_or_blocks
= 0;
1891 /* If this is not a standard conditional jump, we can't parse it. */
1892 jump
= BB_END (test_bb
);
1893 cond
= noce_get_condition (jump
, &if_info
.cond_earliest
);
1897 /* If the conditional jump is more than just a conditional
1898 jump, then we can not do if-conversion on this block. */
1899 if (! onlyjump_p (jump
))
1902 /* We must be comparing objects whose modes imply the size. */
1903 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
1906 /* Look for one of the potential sets. */
1907 insn_a
= first_active_insn (then_bb
);
1909 || insn_a
!= last_active_insn (then_bb
, FALSE
)
1910 || (set_a
= single_set (insn_a
)) == NULL_RTX
)
1913 x
= SET_DEST (set_a
);
1914 a
= SET_SRC (set_a
);
1916 /* Look for the other potential set. Make sure we've got equivalent
1918 /* ??? This is overconservative. Storing to two different mems is
1919 as easy as conditionally computing the address. Storing to a
1920 single mem merely requires a scratch memory to use as one of the
1921 destination addresses; often the memory immediately below the
1922 stack pointer is available for this. */
1926 insn_b
= first_active_insn (else_bb
);
1928 || insn_b
!= last_active_insn (else_bb
, FALSE
)
1929 || (set_b
= single_set (insn_b
)) == NULL_RTX
1930 || ! rtx_equal_p (x
, SET_DEST (set_b
)))
1935 insn_b
= prev_nonnote_insn (if_info
.cond_earliest
);
1936 /* We're going to be moving the evaluation of B down from above
1937 COND_EARLIEST to JUMP. Make sure the relevant data is still
1940 || GET_CODE (insn_b
) != INSN
1941 || (set_b
= single_set (insn_b
)) == NULL_RTX
1942 || ! rtx_equal_p (x
, SET_DEST (set_b
))
1943 || reg_overlap_mentioned_p (x
, SET_SRC (set_b
))
1944 || modified_between_p (SET_SRC (set_b
),
1945 PREV_INSN (if_info
.cond_earliest
), jump
)
1946 /* Likewise with X. In particular this can happen when
1947 noce_get_condition looks farther back in the instruction
1948 stream than one might expect. */
1949 || reg_overlap_mentioned_p (x
, cond
)
1950 || reg_overlap_mentioned_p (x
, a
)
1951 || modified_between_p (x
, PREV_INSN (if_info
.cond_earliest
), jump
))
1952 insn_b
= set_b
= NULL_RTX
;
1955 /* If x has side effects then only the if-then-else form is safe to
1956 convert. But even in that case we would need to restore any notes
1957 (such as REG_INC) at then end. That can be tricky if
1958 noce_emit_move_insn expands to more than one insn, so disable the
1959 optimization entirely for now if there are side effects. */
1960 if (side_effects_p (x
))
1963 b
= (set_b
? SET_SRC (set_b
) : x
);
1965 /* Only operate on register destinations, and even then avoid extending
1966 the lifetime of hard registers on small register class machines. */
1969 || (SMALL_REGISTER_CLASSES
1970 && REGNO (x
) < FIRST_PSEUDO_REGISTER
))
1972 if (no_new_pseudos
|| GET_MODE (x
) == BLKmode
)
1974 x
= gen_reg_rtx (GET_MODE (GET_CODE (x
) == STRICT_LOW_PART
1975 ? XEXP (x
, 0) : x
));
1978 /* Don't operate on sources that may trap or are volatile. */
1979 if (! noce_operand_ok (a
) || ! noce_operand_ok (b
))
1982 /* Set up the info block for our subroutines. */
1983 if_info
.test_bb
= test_bb
;
1984 if_info
.cond
= cond
;
1985 if_info
.jump
= jump
;
1986 if_info
.insn_a
= insn_a
;
1987 if_info
.insn_b
= insn_b
;
1991 if_info
.b_unconditional
= else_bb
== 0;
1993 /* Try optimizations in some approximation of a useful order. */
1994 /* ??? Should first look to see if X is live incoming at all. If it
1995 isn't, we don't need anything but an unconditional set. */
1997 /* Look and see if A and B are really the same. Avoid creating silly
1998 cmove constructs that no one will fix up later. */
1999 if (rtx_equal_p (a
, b
))
2001 /* If we have an INSN_B, we don't have to create any new rtl. Just
2002 move the instruction that we already have. If we don't have an
2003 INSN_B, that means that A == X, and we've got a noop move. In
2004 that case don't do anything and let the code below delete INSN_A. */
2005 if (insn_b
&& else_bb
)
2009 if (else_bb
&& insn_b
== BB_END (else_bb
))
2010 BB_END (else_bb
) = PREV_INSN (insn_b
);
2011 reorder_insns (insn_b
, insn_b
, PREV_INSN (jump
));
2013 /* If there was a REG_EQUAL note, delete it since it may have been
2014 true due to this insn being after a jump. */
2015 if ((note
= find_reg_note (insn_b
, REG_EQUAL
, NULL_RTX
)) != 0)
2016 remove_note (insn_b
, note
);
2020 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
2021 x must be executed twice. */
2022 else if (insn_b
&& side_effects_p (orig_x
))
2029 /* Disallow the "if (...) x = a;" form (with an implicit "else x = x;")
2030 for most optimizations if writing to x may trap, i.e. it's a memory
2031 other than a static var or a stack slot. */
2034 && ! MEM_NOTRAP_P (orig_x
)
2035 && rtx_addr_can_trap_p (XEXP (orig_x
, 0)))
2037 if (HAVE_conditional_move
)
2039 if (noce_try_cmove (&if_info
))
2041 if (! HAVE_conditional_execution
2042 && noce_try_cmove_arith (&if_info
))
2048 if (noce_try_move (&if_info
))
2050 if (noce_try_store_flag (&if_info
))
2052 if (noce_try_minmax (&if_info
))
2054 if (noce_try_abs (&if_info
))
2056 if (HAVE_conditional_move
2057 && noce_try_cmove (&if_info
))
2059 if (! HAVE_conditional_execution
)
2061 if (noce_try_store_flag_constants (&if_info
))
2063 if (noce_try_addcc (&if_info
))
2065 if (noce_try_store_flag_mask (&if_info
))
2067 if (HAVE_conditional_move
2068 && noce_try_cmove_arith (&if_info
))
2070 if (noce_try_sign_mask (&if_info
))
2077 /* The original sets may now be killed. */
2078 delete_insn (insn_a
);
2080 /* Several special cases here: First, we may have reused insn_b above,
2081 in which case insn_b is now NULL. Second, we want to delete insn_b
2082 if it came from the ELSE block, because follows the now correct
2083 write that appears in the TEST block. However, if we got insn_b from
2084 the TEST block, it may in fact be loading data needed for the comparison.
2085 We'll let life_analysis remove the insn if it's really dead. */
2086 if (insn_b
&& else_bb
)
2087 delete_insn (insn_b
);
2089 /* The new insns will have been inserted immediately before the jump. We
2090 should be able to remove the jump with impunity, but the condition itself
2091 may have been modified by gcse to be shared across basic blocks. */
2094 /* If we used a temporary, fix it up now. */
2098 noce_emit_move_insn (orig_x
, x
);
2099 insn_b
= get_insns ();
2100 set_used_flags (orig_x
);
2101 unshare_all_rtl_in_chain (insn_b
);
2104 emit_insn_after_setloc (insn_b
, BB_END (test_bb
), INSN_LOCATOR (insn_a
));
2107 /* Merge the blocks! */
2108 merge_if_block (ce_info
);
2113 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
2114 straight line code. Return true if successful. */
2117 process_if_block (struct ce_if_block
* ce_info
)
2119 if (! reload_completed
2120 && noce_process_if_block (ce_info
))
2123 if (HAVE_conditional_execution
&& reload_completed
)
2125 /* If we have && and || tests, try to first handle combining the && and
2126 || tests into the conditional code, and if that fails, go back and
2127 handle it without the && and ||, which at present handles the && case
2128 if there was no ELSE block. */
2129 if (cond_exec_process_if_block (ce_info
, TRUE
))
2132 if (ce_info
->num_multiple_test_blocks
)
2136 if (cond_exec_process_if_block (ce_info
, FALSE
))
2144 /* Merge the blocks and mark for local life update. */
2147 merge_if_block (struct ce_if_block
* ce_info
)
2149 basic_block test_bb
= ce_info
->test_bb
; /* last test block */
2150 basic_block then_bb
= ce_info
->then_bb
; /* THEN */
2151 basic_block else_bb
= ce_info
->else_bb
; /* ELSE or NULL */
2152 basic_block join_bb
= ce_info
->join_bb
; /* join block */
2153 basic_block combo_bb
;
2155 /* All block merging is done into the lower block numbers. */
2159 /* Merge any basic blocks to handle && and || subtests. Each of
2160 the blocks are on the fallthru path from the predecessor block. */
2161 if (ce_info
->num_multiple_test_blocks
> 0)
2163 basic_block bb
= test_bb
;
2164 basic_block last_test_bb
= ce_info
->last_test_bb
;
2165 basic_block fallthru
= block_fallthru (bb
);
2170 fallthru
= block_fallthru (bb
);
2171 merge_blocks (combo_bb
, bb
);
2174 while (bb
!= last_test_bb
);
2177 /* Merge TEST block into THEN block. Normally the THEN block won't have a
2178 label, but it might if there were || tests. That label's count should be
2179 zero, and it normally should be removed. */
2183 if (combo_bb
->global_live_at_end
)
2184 COPY_REG_SET (combo_bb
->global_live_at_end
,
2185 then_bb
->global_live_at_end
);
2186 merge_blocks (combo_bb
, then_bb
);
2190 /* The ELSE block, if it existed, had a label. That label count
2191 will almost always be zero, but odd things can happen when labels
2192 get their addresses taken. */
2195 merge_blocks (combo_bb
, else_bb
);
2199 /* If there was no join block reported, that means it was not adjacent
2200 to the others, and so we cannot merge them. */
2204 rtx last
= BB_END (combo_bb
);
2206 /* The outgoing edge for the current COMBO block should already
2207 be correct. Verify this. */
2208 if (combo_bb
->succ
== NULL_EDGE
)
2210 if (find_reg_note (last
, REG_NORETURN
, NULL
))
2212 else if (GET_CODE (last
) == INSN
2213 && GET_CODE (PATTERN (last
)) == TRAP_IF
2214 && TRAP_CONDITION (PATTERN (last
)) == const_true_rtx
)
2220 /* There should still be something at the end of the THEN or ELSE
2221 blocks taking us to our final destination. */
2222 else if (GET_CODE (last
) == JUMP_INSN
)
2224 else if (combo_bb
->succ
->dest
== EXIT_BLOCK_PTR
2225 && GET_CODE (last
) == CALL_INSN
2226 && SIBLING_CALL_P (last
))
2228 else if ((combo_bb
->succ
->flags
& EDGE_EH
)
2229 && can_throw_internal (last
))
2235 /* The JOIN block may have had quite a number of other predecessors too.
2236 Since we've already merged the TEST, THEN and ELSE blocks, we should
2237 have only one remaining edge from our if-then-else diamond. If there
2238 is more than one remaining edge, it must come from elsewhere. There
2239 may be zero incoming edges if the THEN block didn't actually join
2240 back up (as with a call to abort). */
2241 else if ((join_bb
->pred
== NULL
2242 || join_bb
->pred
->pred_next
== NULL
)
2243 && join_bb
!= EXIT_BLOCK_PTR
)
2245 /* We can merge the JOIN. */
2246 if (combo_bb
->global_live_at_end
)
2247 COPY_REG_SET (combo_bb
->global_live_at_end
,
2248 join_bb
->global_live_at_end
);
2250 merge_blocks (combo_bb
, join_bb
);
2255 /* We cannot merge the JOIN. */
2257 /* The outgoing edge for the current COMBO block should already
2258 be correct. Verify this. */
2259 if (combo_bb
->succ
->succ_next
!= NULL_EDGE
2260 || combo_bb
->succ
->dest
!= join_bb
)
2263 /* Remove the jump and cruft from the end of the COMBO block. */
2264 if (join_bb
!= EXIT_BLOCK_PTR
)
2265 tidy_fallthru_edge (combo_bb
->succ
);
2268 num_updated_if_blocks
++;
2271 /* Find a block ending in a simple IF condition and try to transform it
2272 in some way. When converting a multi-block condition, put the new code
2273 in the first such block and delete the rest. Return a pointer to this
2274 first block if some transformation was done. Return NULL otherwise. */
2277 find_if_header (basic_block test_bb
, int pass
)
2279 ce_if_block_t ce_info
;
2283 /* The kind of block we're looking for has exactly two successors. */
2284 if ((then_edge
= test_bb
->succ
) == NULL_EDGE
2285 || (else_edge
= then_edge
->succ_next
) == NULL_EDGE
2286 || else_edge
->succ_next
!= NULL_EDGE
)
2289 /* Neither edge should be abnormal. */
2290 if ((then_edge
->flags
& EDGE_COMPLEX
)
2291 || (else_edge
->flags
& EDGE_COMPLEX
))
2294 /* Nor exit the loop. */
2295 if ((then_edge
->flags
& EDGE_LOOP_EXIT
)
2296 || (else_edge
->flags
& EDGE_LOOP_EXIT
))
2299 /* The THEN edge is canonically the one that falls through. */
2300 if (then_edge
->flags
& EDGE_FALLTHRU
)
2302 else if (else_edge
->flags
& EDGE_FALLTHRU
)
2305 else_edge
= then_edge
;
2309 /* Otherwise this must be a multiway branch of some sort. */
2312 memset (&ce_info
, '\0', sizeof (ce_info
));
2313 ce_info
.test_bb
= test_bb
;
2314 ce_info
.then_bb
= then_edge
->dest
;
2315 ce_info
.else_bb
= else_edge
->dest
;
2316 ce_info
.pass
= pass
;
2318 #ifdef IFCVT_INIT_EXTRA_FIELDS
2319 IFCVT_INIT_EXTRA_FIELDS (&ce_info
);
2322 if (find_if_block (&ce_info
))
2325 if (HAVE_trap
&& HAVE_conditional_trap
2326 && find_cond_trap (test_bb
, then_edge
, else_edge
))
2329 if (dom_computed
[CDI_POST_DOMINATORS
] >= DOM_NO_FAST_QUERY
2330 && (! HAVE_conditional_execution
|| reload_completed
))
2332 if (find_if_case_1 (test_bb
, then_edge
, else_edge
))
2334 if (find_if_case_2 (test_bb
, then_edge
, else_edge
))
2342 fprintf (dump_file
, "Conversion succeeded on pass %d.\n", pass
);
2343 return ce_info
.test_bb
;
2346 /* Return true if a block has two edges, one of which falls through to the next
2347 block, and the other jumps to a specific block, so that we can tell if the
2348 block is part of an && test or an || test. Returns either -1 or the number
2349 of non-note, non-jump, non-USE/CLOBBER insns in the block. */
2352 block_jumps_and_fallthru_p (basic_block cur_bb
, basic_block target_bb
)
2355 int fallthru_p
= FALSE
;
2361 if (!cur_bb
|| !target_bb
)
2364 /* If no edges, obviously it doesn't jump or fallthru. */
2365 if (cur_bb
->succ
== NULL_EDGE
)
2368 for (cur_edge
= cur_bb
->succ
;
2369 cur_edge
!= NULL_EDGE
;
2370 cur_edge
= cur_edge
->succ_next
)
2372 if (cur_edge
->flags
& EDGE_COMPLEX
)
2373 /* Anything complex isn't what we want. */
2376 else if (cur_edge
->flags
& EDGE_FALLTHRU
)
2379 else if (cur_edge
->dest
== target_bb
)
2386 if ((jump_p
& fallthru_p
) == 0)
2389 /* Don't allow calls in the block, since this is used to group && and ||
2390 together for conditional execution support. ??? we should support
2391 conditional execution support across calls for IA-64 some day, but
2392 for now it makes the code simpler. */
2393 end
= BB_END (cur_bb
);
2394 insn
= BB_HEAD (cur_bb
);
2396 while (insn
!= NULL_RTX
)
2398 if (GET_CODE (insn
) == CALL_INSN
)
2402 && GET_CODE (insn
) != JUMP_INSN
2403 && GET_CODE (PATTERN (insn
)) != USE
2404 && GET_CODE (PATTERN (insn
)) != CLOBBER
)
2410 insn
= NEXT_INSN (insn
);
2416 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
2417 block. If so, we'll try to convert the insns to not require the branch.
2418 Return TRUE if we were successful at converting the block. */
2421 find_if_block (struct ce_if_block
* ce_info
)
2423 basic_block test_bb
= ce_info
->test_bb
;
2424 basic_block then_bb
= ce_info
->then_bb
;
2425 basic_block else_bb
= ce_info
->else_bb
;
2426 basic_block join_bb
= NULL_BLOCK
;
2427 edge then_succ
= then_bb
->succ
;
2428 edge else_succ
= else_bb
->succ
;
2429 int then_predecessors
;
2430 int else_predecessors
;
2434 ce_info
->last_test_bb
= test_bb
;
2436 /* Discover if any fall through predecessors of the current test basic block
2437 were && tests (which jump to the else block) or || tests (which jump to
2439 if (HAVE_conditional_execution
&& reload_completed
2440 && test_bb
->pred
!= NULL_EDGE
2441 && test_bb
->pred
->pred_next
== NULL_EDGE
2442 && test_bb
->pred
->flags
== EDGE_FALLTHRU
)
2444 basic_block bb
= test_bb
->pred
->src
;
2445 basic_block target_bb
;
2446 int max_insns
= MAX_CONDITIONAL_EXECUTE
;
2449 /* Determine if the preceding block is an && or || block. */
2450 if ((n_insns
= block_jumps_and_fallthru_p (bb
, else_bb
)) >= 0)
2452 ce_info
->and_and_p
= TRUE
;
2453 target_bb
= else_bb
;
2455 else if ((n_insns
= block_jumps_and_fallthru_p (bb
, then_bb
)) >= 0)
2457 ce_info
->and_and_p
= FALSE
;
2458 target_bb
= then_bb
;
2461 target_bb
= NULL_BLOCK
;
2463 if (target_bb
&& n_insns
<= max_insns
)
2465 int total_insns
= 0;
2468 ce_info
->last_test_bb
= test_bb
;
2470 /* Found at least one && or || block, look for more. */
2473 ce_info
->test_bb
= test_bb
= bb
;
2474 total_insns
+= n_insns
;
2477 if (bb
->pred
== NULL_EDGE
|| bb
->pred
->pred_next
!= NULL_EDGE
)
2481 n_insns
= block_jumps_and_fallthru_p (bb
, target_bb
);
2483 while (n_insns
>= 0 && (total_insns
+ n_insns
) <= max_insns
);
2485 ce_info
->num_multiple_test_blocks
= blocks
;
2486 ce_info
->num_multiple_test_insns
= total_insns
;
2488 if (ce_info
->and_and_p
)
2489 ce_info
->num_and_and_blocks
= blocks
;
2491 ce_info
->num_or_or_blocks
= blocks
;
2495 /* Count the number of edges the THEN and ELSE blocks have. */
2496 then_predecessors
= 0;
2497 for (cur_edge
= then_bb
->pred
;
2498 cur_edge
!= NULL_EDGE
;
2499 cur_edge
= cur_edge
->pred_next
)
2501 then_predecessors
++;
2502 if (cur_edge
->flags
& EDGE_COMPLEX
)
2506 else_predecessors
= 0;
2507 for (cur_edge
= else_bb
->pred
;
2508 cur_edge
!= NULL_EDGE
;
2509 cur_edge
= cur_edge
->pred_next
)
2511 else_predecessors
++;
2512 if (cur_edge
->flags
& EDGE_COMPLEX
)
2516 /* The THEN block of an IF-THEN combo must have exactly one predecessor,
2517 other than any || blocks which jump to the THEN block. */
2518 if ((then_predecessors
- ce_info
->num_or_or_blocks
) != 1)
2521 /* The THEN block of an IF-THEN combo must have zero or one successors. */
2522 if (then_succ
!= NULL_EDGE
2523 && (then_succ
->succ_next
!= NULL_EDGE
2524 || (then_succ
->flags
& EDGE_COMPLEX
)
2525 || (flow2_completed
&& tablejump_p (BB_END (then_bb
), NULL
, NULL
))))
2528 /* If the THEN block has no successors, conditional execution can still
2529 make a conditional call. Don't do this unless the ELSE block has
2530 only one incoming edge -- the CFG manipulation is too ugly otherwise.
2531 Check for the last insn of the THEN block being an indirect jump, which
2532 is listed as not having any successors, but confuses the rest of the CE
2533 code processing. ??? we should fix this in the future. */
2534 if (then_succ
== NULL
)
2536 if (else_bb
->pred
->pred_next
== NULL_EDGE
)
2538 rtx last_insn
= BB_END (then_bb
);
2541 && GET_CODE (last_insn
) == NOTE
2542 && last_insn
!= BB_HEAD (then_bb
))
2543 last_insn
= PREV_INSN (last_insn
);
2546 && GET_CODE (last_insn
) == JUMP_INSN
2547 && ! simplejump_p (last_insn
))
2551 else_bb
= NULL_BLOCK
;
2557 /* If the THEN block's successor is the other edge out of the TEST block,
2558 then we have an IF-THEN combo without an ELSE. */
2559 else if (then_succ
->dest
== else_bb
)
2562 else_bb
= NULL_BLOCK
;
2565 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2566 has exactly one predecessor and one successor, and the outgoing edge
2567 is not complex, then we have an IF-THEN-ELSE combo. */
2568 else if (else_succ
!= NULL_EDGE
2569 && then_succ
->dest
== else_succ
->dest
2570 && else_bb
->pred
->pred_next
== NULL_EDGE
2571 && else_succ
->succ_next
== NULL_EDGE
2572 && ! (else_succ
->flags
& EDGE_COMPLEX
)
2573 && ! (flow2_completed
&& tablejump_p (BB_END (else_bb
), NULL
, NULL
)))
2574 join_bb
= else_succ
->dest
;
2576 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2580 num_possible_if_blocks
++;
2585 "\nIF-THEN%s block found, pass %d, start block %d "
2586 "[insn %d], then %d [%d]",
2587 (else_bb
) ? "-ELSE" : "",
2590 BB_HEAD (test_bb
) ? (int)INSN_UID (BB_HEAD (test_bb
)) : -1,
2592 BB_HEAD (then_bb
) ? (int)INSN_UID (BB_HEAD (then_bb
)) : -1);
2595 fprintf (dump_file
, ", else %d [%d]",
2597 BB_HEAD (else_bb
) ? (int)INSN_UID (BB_HEAD (else_bb
)) : -1);
2599 fprintf (dump_file
, ", join %d [%d]",
2601 BB_HEAD (join_bb
) ? (int)INSN_UID (BB_HEAD (join_bb
)) : -1);
2603 if (ce_info
->num_multiple_test_blocks
> 0)
2604 fprintf (dump_file
, ", %d %s block%s last test %d [%d]",
2605 ce_info
->num_multiple_test_blocks
,
2606 (ce_info
->and_and_p
) ? "&&" : "||",
2607 (ce_info
->num_multiple_test_blocks
== 1) ? "" : "s",
2608 ce_info
->last_test_bb
->index
,
2609 ((BB_HEAD (ce_info
->last_test_bb
))
2610 ? (int)INSN_UID (BB_HEAD (ce_info
->last_test_bb
))
2613 fputc ('\n', dump_file
);
2616 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we get the
2617 first condition for free, since we've already asserted that there's a
2618 fallthru edge from IF to THEN. Likewise for the && and || blocks, since
2619 we checked the FALLTHRU flag, those are already adjacent to the last IF
2621 /* ??? As an enhancement, move the ELSE block. Have to deal with
2622 BLOCK notes, if by no other means than aborting the merge if they
2623 exist. Sticky enough I don't want to think about it now. */
2625 if (else_bb
&& (next
= next
->next_bb
) != else_bb
)
2627 if ((next
= next
->next_bb
) != join_bb
&& join_bb
!= EXIT_BLOCK_PTR
)
2635 /* Do the real work. */
2636 ce_info
->else_bb
= else_bb
;
2637 ce_info
->join_bb
= join_bb
;
2639 return process_if_block (ce_info
);
2642 /* Convert a branch over a trap, or a branch
2643 to a trap, into a conditional trap. */
2646 find_cond_trap (basic_block test_bb
, edge then_edge
, edge else_edge
)
2648 basic_block then_bb
= then_edge
->dest
;
2649 basic_block else_bb
= else_edge
->dest
;
2650 basic_block other_bb
, trap_bb
;
2651 rtx trap
, jump
, cond
, cond_earliest
, seq
;
2654 /* Locate the block with the trap instruction. */
2655 /* ??? While we look for no successors, we really ought to allow
2656 EH successors. Need to fix merge_if_block for that to work. */
2657 if ((trap
= block_has_only_trap (then_bb
)) != NULL
)
2658 trap_bb
= then_bb
, other_bb
= else_bb
;
2659 else if ((trap
= block_has_only_trap (else_bb
)) != NULL
)
2660 trap_bb
= else_bb
, other_bb
= then_bb
;
2666 fprintf (dump_file
, "\nTRAP-IF block found, start %d, trap %d\n",
2667 test_bb
->index
, trap_bb
->index
);
2670 /* If this is not a standard conditional jump, we can't parse it. */
2671 jump
= BB_END (test_bb
);
2672 cond
= noce_get_condition (jump
, &cond_earliest
);
2676 /* If the conditional jump is more than just a conditional jump, then
2677 we can not do if-conversion on this block. */
2678 if (! onlyjump_p (jump
))
2681 /* We must be comparing objects whose modes imply the size. */
2682 if (GET_MODE (XEXP (cond
, 0)) == BLKmode
)
2685 /* Reverse the comparison code, if necessary. */
2686 code
= GET_CODE (cond
);
2687 if (then_bb
== trap_bb
)
2689 code
= reversed_comparison_code (cond
, jump
);
2690 if (code
== UNKNOWN
)
2694 /* Attempt to generate the conditional trap. */
2695 seq
= gen_cond_trap (code
, XEXP (cond
, 0),
2697 TRAP_CODE (PATTERN (trap
)));
2703 /* Emit the new insns before cond_earliest. */
2704 emit_insn_before_setloc (seq
, cond_earliest
, INSN_LOCATOR (trap
));
2706 /* Delete the trap block if possible. */
2707 remove_edge (trap_bb
== then_bb
? then_edge
: else_edge
);
2708 if (trap_bb
->pred
== NULL
)
2709 delete_basic_block (trap_bb
);
2711 /* If the non-trap block and the test are now adjacent, merge them.
2712 Otherwise we must insert a direct branch. */
2713 if (test_bb
->next_bb
== other_bb
)
2715 struct ce_if_block new_ce_info
;
2717 memset (&new_ce_info
, '\0', sizeof (new_ce_info
));
2718 new_ce_info
.test_bb
= test_bb
;
2719 new_ce_info
.then_bb
= NULL
;
2720 new_ce_info
.else_bb
= NULL
;
2721 new_ce_info
.join_bb
= other_bb
;
2722 merge_if_block (&new_ce_info
);
2728 lab
= JUMP_LABEL (jump
);
2729 newjump
= emit_jump_insn_after (gen_jump (lab
), jump
);
2730 LABEL_NUSES (lab
) += 1;
2731 JUMP_LABEL (newjump
) = lab
;
2732 emit_barrier_after (newjump
);
2740 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2744 block_has_only_trap (basic_block bb
)
2748 /* We're not the exit block. */
2749 if (bb
== EXIT_BLOCK_PTR
)
2752 /* The block must have no successors. */
2756 /* The only instruction in the THEN block must be the trap. */
2757 trap
= first_active_insn (bb
);
2758 if (! (trap
== BB_END (bb
)
2759 && GET_CODE (PATTERN (trap
)) == TRAP_IF
2760 && TRAP_CONDITION (PATTERN (trap
)) == const_true_rtx
))
2766 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2767 transformable, but not necessarily the other. There need be no
2770 Return TRUE if we were successful at converting the block.
2772 Cases we'd like to look at:
2775 if (test) goto over; // x not live
2783 if (! test) goto label;
2786 if (test) goto E; // x not live
2800 (3) // This one's really only interesting for targets that can do
2801 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2802 // it results in multiple branches on a cache line, which often
2803 // does not sit well with predictors.
2805 if (test1) goto E; // predicted not taken
2821 (A) Don't do (2) if the branch is predicted against the block we're
2822 eliminating. Do it anyway if we can eliminate a branch; this requires
2823 that the sole successor of the eliminated block postdominate the other
2826 (B) With CE, on (3) we can steal from both sides of the if, creating
2835 Again, this is most useful if J postdominates.
2837 (C) CE substitutes for helpful life information.
2839 (D) These heuristics need a lot of work. */
2841 /* Tests for case 1 above. */
2844 find_if_case_1 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2846 basic_block then_bb
= then_edge
->dest
;
2847 basic_block else_bb
= else_edge
->dest
, new_bb
;
2848 edge then_succ
= then_bb
->succ
;
2851 /* If we are partitioning hot/cold basic blocks, we don't want to
2852 mess up unconditional or indirect jumps that cross between hot
2853 and cold sections. */
2855 if (flag_reorder_blocks_and_partition
2856 && ((BB_END (then_bb
)
2857 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2858 || (BB_END (else_bb
)
2859 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2863 /* THEN has one successor. */
2864 if (!then_succ
|| then_succ
->succ_next
!= NULL
)
2867 /* THEN does not fall through, but is not strange either. */
2868 if (then_succ
->flags
& (EDGE_COMPLEX
| EDGE_FALLTHRU
))
2871 /* THEN has one predecessor. */
2872 if (then_bb
->pred
->pred_next
!= NULL
)
2875 /* THEN must do something. */
2876 if (forwarder_block_p (then_bb
))
2879 num_possible_if_blocks
++;
2882 "\nIF-CASE-1 found, start %d, then %d\n",
2883 test_bb
->index
, then_bb
->index
);
2885 /* THEN is small. */
2886 if (count_bb_insns (then_bb
) > BRANCH_COST
)
2889 /* Registers set are dead, or are predicable. */
2890 if (! dead_or_predicable (test_bb
, then_bb
, else_bb
,
2891 then_bb
->succ
->dest
, 1))
2894 /* Conversion went ok, including moving the insns and fixing up the
2895 jump. Adjust the CFG to match. */
2897 bitmap_operation (test_bb
->global_live_at_end
,
2898 else_bb
->global_live_at_start
,
2899 then_bb
->global_live_at_end
, BITMAP_IOR
);
2901 new_bb
= redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb
), else_bb
);
2902 then_bb_index
= then_bb
->index
;
2903 delete_basic_block (then_bb
);
2905 /* Make rest of code believe that the newly created block is the THEN_BB
2906 block we removed. */
2909 new_bb
->index
= then_bb_index
;
2910 BASIC_BLOCK (then_bb_index
) = new_bb
;
2912 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2916 num_updated_if_blocks
++;
2921 /* Test for case 2 above. */
2924 find_if_case_2 (basic_block test_bb
, edge then_edge
, edge else_edge
)
2926 basic_block then_bb
= then_edge
->dest
;
2927 basic_block else_bb
= else_edge
->dest
;
2928 edge else_succ
= else_bb
->succ
;
2931 /* If we are partitioning hot/cold basic blocks, we don't want to
2932 mess up unconditional or indirect jumps that cross between hot
2933 and cold sections. */
2935 if (flag_reorder_blocks_and_partition
2936 && ((BB_END (then_bb
)
2937 && find_reg_note (BB_END (then_bb
), REG_CROSSING_JUMP
, NULL_RTX
))
2938 || (BB_END (else_bb
)
2939 && find_reg_note (BB_END (else_bb
), REG_CROSSING_JUMP
,
2943 /* ELSE has one successor. */
2944 if (!else_succ
|| else_succ
->succ_next
!= NULL
)
2947 /* ELSE outgoing edge is not complex. */
2948 if (else_succ
->flags
& EDGE_COMPLEX
)
2951 /* ELSE has one predecessor. */
2952 if (else_bb
->pred
->pred_next
!= NULL
)
2955 /* THEN is not EXIT. */
2956 if (then_bb
->index
< 0)
2959 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2960 note
= find_reg_note (BB_END (test_bb
), REG_BR_PROB
, NULL_RTX
);
2961 if (note
&& INTVAL (XEXP (note
, 0)) >= REG_BR_PROB_BASE
/ 2)
2963 else if (else_succ
->dest
->index
< 0
2964 || dominated_by_p (CDI_POST_DOMINATORS
, then_bb
,
2970 num_possible_if_blocks
++;
2973 "\nIF-CASE-2 found, start %d, else %d\n",
2974 test_bb
->index
, else_bb
->index
);
2976 /* ELSE is small. */
2977 if (count_bb_insns (else_bb
) > BRANCH_COST
)
2980 /* Registers set are dead, or are predicable. */
2981 if (! dead_or_predicable (test_bb
, else_bb
, then_bb
, else_succ
->dest
, 0))
2984 /* Conversion went ok, including moving the insns and fixing up the
2985 jump. Adjust the CFG to match. */
2987 bitmap_operation (test_bb
->global_live_at_end
,
2988 then_bb
->global_live_at_start
,
2989 else_bb
->global_live_at_end
, BITMAP_IOR
);
2991 delete_basic_block (else_bb
);
2994 num_updated_if_blocks
++;
2996 /* ??? We may now fallthru from one of THEN's successors into a join
2997 block. Rerun cleanup_cfg? Examine things manually? Wait? */
3002 /* A subroutine of dead_or_predicable called through for_each_rtx.
3003 Return 1 if a memory is found. */
3006 find_memory (rtx
*px
, void *data ATTRIBUTE_UNUSED
)
3011 /* Used by the code above to perform the actual rtl transformations.
3012 Return TRUE if successful.
3014 TEST_BB is the block containing the conditional branch. MERGE_BB
3015 is the block containing the code to manipulate. NEW_DEST is the
3016 label TEST_BB should be branching to after the conversion.
3017 REVERSEP is true if the sense of the branch should be reversed. */
3020 dead_or_predicable (basic_block test_bb
, basic_block merge_bb
,
3021 basic_block other_bb
, basic_block new_dest
, int reversep
)
3023 rtx head
, end
, jump
, earliest
= NULL_RTX
, old_dest
, new_label
= NULL_RTX
;
3025 jump
= BB_END (test_bb
);
3027 /* Find the extent of the real code in the merge block. */
3028 head
= BB_HEAD (merge_bb
);
3029 end
= BB_END (merge_bb
);
3031 if (GET_CODE (head
) == CODE_LABEL
)
3032 head
= NEXT_INSN (head
);
3033 if (GET_CODE (head
) == NOTE
)
3037 head
= end
= NULL_RTX
;
3040 head
= NEXT_INSN (head
);
3043 if (GET_CODE (end
) == JUMP_INSN
)
3047 head
= end
= NULL_RTX
;
3050 end
= PREV_INSN (end
);
3053 /* Disable handling dead code by conditional execution if the machine needs
3054 to do anything funny with the tests, etc. */
3055 #ifndef IFCVT_MODIFY_TESTS
3056 if (HAVE_conditional_execution
)
3058 /* In the conditional execution case, we have things easy. We know
3059 the condition is reversible. We don't have to check life info
3060 because we're going to conditionally execute the code anyway.
3061 All that's left is making sure the insns involved can actually
3066 cond
= cond_exec_get_condition (jump
);
3070 prob_val
= find_reg_note (jump
, REG_BR_PROB
, NULL_RTX
);
3072 prob_val
= XEXP (prob_val
, 0);
3076 enum rtx_code rev
= reversed_comparison_code (cond
, jump
);
3079 cond
= gen_rtx_fmt_ee (rev
, GET_MODE (cond
), XEXP (cond
, 0),
3082 prob_val
= GEN_INT (REG_BR_PROB_BASE
- INTVAL (prob_val
));
3085 if (! cond_exec_process_insns ((ce_if_block_t
*)0, head
, end
, cond
,
3094 /* In the non-conditional execution case, we have to verify that there
3095 are no trapping operations, no calls, no references to memory, and
3096 that any registers modified are dead at the branch site. */
3098 rtx insn
, cond
, prev
;
3099 regset_head merge_set_head
, tmp_head
, test_live_head
, test_set_head
;
3100 regset merge_set
, tmp
, test_live
, test_set
;
3101 struct propagate_block_info
*pbi
;
3104 /* Check for no calls or trapping operations. */
3105 for (insn
= head
; ; insn
= NEXT_INSN (insn
))
3107 if (GET_CODE (insn
) == CALL_INSN
)
3111 if (may_trap_p (PATTERN (insn
)))
3114 /* ??? Even non-trapping memories such as stack frame
3115 references must be avoided. For stores, we collect
3116 no lifetime info; for reads, we'd have to assert
3117 true_dependence false against every store in the
3119 if (for_each_rtx (&PATTERN (insn
), find_memory
, NULL
))
3126 if (! any_condjump_p (jump
))
3129 /* Find the extent of the conditional. */
3130 cond
= noce_get_condition (jump
, &earliest
);
3135 MERGE_SET = set of registers set in MERGE_BB
3136 TEST_LIVE = set of registers live at EARLIEST
3137 TEST_SET = set of registers set between EARLIEST and the
3138 end of the block. */
3140 tmp
= INITIALIZE_REG_SET (tmp_head
);
3141 merge_set
= INITIALIZE_REG_SET (merge_set_head
);
3142 test_live
= INITIALIZE_REG_SET (test_live_head
);
3143 test_set
= INITIALIZE_REG_SET (test_set_head
);
3145 /* ??? bb->local_set is only valid during calculate_global_regs_live,
3146 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
3147 since we've already asserted that MERGE_BB is small. */
3148 propagate_block (merge_bb
, tmp
, merge_set
, merge_set
, 0);
3150 /* For small register class machines, don't lengthen lifetimes of
3151 hard registers before reload. */
3152 if (SMALL_REGISTER_CLASSES
&& ! reload_completed
)
3154 EXECUTE_IF_SET_IN_BITMAP
3157 if (i
< FIRST_PSEUDO_REGISTER
3159 && ! global_regs
[i
])
3164 /* For TEST, we're interested in a range of insns, not a whole block.
3165 Moreover, we're interested in the insns live from OTHER_BB. */
3167 COPY_REG_SET (test_live
, other_bb
->global_live_at_start
);
3168 pbi
= init_propagate_block_info (test_bb
, test_live
, test_set
, test_set
,
3171 for (insn
= jump
; ; insn
= prev
)
3173 prev
= propagate_one_insn (pbi
, insn
);
3174 if (insn
== earliest
)
3178 free_propagate_block_info (pbi
);
3180 /* We can perform the transformation if
3181 MERGE_SET & (TEST_SET | TEST_LIVE)
3183 TEST_SET & merge_bb->global_live_at_start
3186 bitmap_operation (tmp
, test_set
, test_live
, BITMAP_IOR
);
3187 bitmap_operation (tmp
, tmp
, merge_set
, BITMAP_AND
);
3188 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
3190 bitmap_operation (tmp
, test_set
, merge_bb
->global_live_at_start
,
3192 EXECUTE_IF_SET_IN_BITMAP(tmp
, 0, i
, fail
= 1);
3195 FREE_REG_SET (merge_set
);
3196 FREE_REG_SET (test_live
);
3197 FREE_REG_SET (test_set
);
3204 /* We don't want to use normal invert_jump or redirect_jump because
3205 we don't want to delete_insn called. Also, we want to do our own
3206 change group management. */
3208 old_dest
= JUMP_LABEL (jump
);
3209 if (other_bb
!= new_dest
)
3211 new_label
= block_label (new_dest
);
3213 ? ! invert_jump_1 (jump
, new_label
)
3214 : ! redirect_jump_1 (jump
, new_label
))
3218 if (! apply_change_group ())
3221 if (other_bb
!= new_dest
)
3224 LABEL_NUSES (old_dest
) -= 1;
3226 LABEL_NUSES (new_label
) += 1;
3227 JUMP_LABEL (jump
) = new_label
;
3229 invert_br_probabilities (jump
);
3231 redirect_edge_succ (BRANCH_EDGE (test_bb
), new_dest
);
3234 gcov_type count
, probability
;
3235 count
= BRANCH_EDGE (test_bb
)->count
;
3236 BRANCH_EDGE (test_bb
)->count
= FALLTHRU_EDGE (test_bb
)->count
;
3237 FALLTHRU_EDGE (test_bb
)->count
= count
;
3238 probability
= BRANCH_EDGE (test_bb
)->probability
;
3239 BRANCH_EDGE (test_bb
)->probability
3240 = FALLTHRU_EDGE (test_bb
)->probability
;
3241 FALLTHRU_EDGE (test_bb
)->probability
= probability
;
3242 update_br_prob_note (test_bb
);
3246 /* Move the insns out of MERGE_BB to before the branch. */
3249 if (end
== BB_END (merge_bb
))
3250 BB_END (merge_bb
) = PREV_INSN (head
);
3252 if (squeeze_notes (&head
, &end
))
3255 reorder_insns (head
, end
, PREV_INSN (earliest
));
3258 /* Remove the jump and edge if we can. */
3259 if (other_bb
== new_dest
)
3262 remove_edge (BRANCH_EDGE (test_bb
));
3263 /* ??? Can't merge blocks here, as then_bb is still in use.
3264 At minimum, the merge will get done just before bb-reorder. */
3274 /* Main entry point for all if-conversion. */
3277 if_convert (int x_life_data_ok
)
3282 num_possible_if_blocks
= 0;
3283 num_updated_if_blocks
= 0;
3284 num_true_changes
= 0;
3285 life_data_ok
= (x_life_data_ok
!= 0);
3287 if ((! targetm
.cannot_modify_jumps_p ())
3288 && (!flag_reorder_blocks_and_partition
|| !no_new_pseudos
))
3289 mark_loop_exit_edges ();
3291 /* Compute postdominators if we think we'll use them. */
3292 if (HAVE_conditional_execution
|| life_data_ok
)
3293 calculate_dominance_info (CDI_POST_DOMINATORS
);
3298 /* Go through each of the basic blocks looking for things to convert. If we
3299 have conditional execution, we make multiple passes to allow us to handle
3300 IF-THEN{-ELSE} blocks within other IF-THEN{-ELSE} blocks. */
3304 cond_exec_changed_p
= FALSE
;
3307 #ifdef IFCVT_MULTIPLE_DUMPS
3308 if (dump_file
&& pass
> 1)
3309 fprintf (dump_file
, "\n\n========== Pass %d ==========\n", pass
);
3315 while ((new_bb
= find_if_header (bb
, pass
)))
3319 #ifdef IFCVT_MULTIPLE_DUMPS
3320 if (dump_file
&& cond_exec_changed_p
)
3321 print_rtl_with_bb (dump_file
, get_insns ());
3324 while (cond_exec_changed_p
);
3326 #ifdef IFCVT_MULTIPLE_DUMPS
3328 fprintf (dump_file
, "\n\n========== no more changes\n");
3331 free_dominance_info (CDI_POST_DOMINATORS
);
3336 clear_aux_for_blocks ();
3338 /* Rebuild life info for basic blocks that require it. */
3339 if (num_true_changes
&& life_data_ok
)
3341 /* If we allocated new pseudos, we must resize the array for sched1. */
3342 if (max_regno
< max_reg_num ())
3344 max_regno
= max_reg_num ();
3345 allocate_reg_info (max_regno
, FALSE
, FALSE
);
3347 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES
,
3348 PROP_DEATH_NOTES
| PROP_SCAN_DEAD_CODE
3349 | PROP_KILL_DEAD_CODE
);
3352 /* Write the final stats. */
3353 if (dump_file
&& num_possible_if_blocks
> 0)
3356 "\n%d possible IF blocks searched.\n",
3357 num_possible_if_blocks
);
3359 "%d IF blocks converted.\n",
3360 num_updated_if_blocks
);
3362 "%d true changes made.\n\n\n",
3366 #ifdef ENABLE_CHECKING
3367 verify_flow_info ();