1 /* If-conversion support.
2 Copyright (C) 2000 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it 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 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
28 #include "insn-config.h"
30 #include "hard-reg-set.h"
31 #include "basic-block.h"
39 #ifndef HAVE_conditional_execution
40 #define HAVE_conditional_execution 0
42 #ifndef HAVE_conditional_move
43 #define HAVE_conditional_move 0
54 #ifndef HAVE_conditional_trap
55 #define HAVE_conditional_trap 0
58 #ifndef MAX_CONDITIONAL_EXECUTE
59 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
62 #define NULL_EDGE ((struct edge_def *)NULL)
63 #define NULL_BLOCK ((struct basic_block_def *)NULL)
65 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
66 static int num_possible_if_blocks;
68 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
70 static int num_updated_if_blocks;
72 /* # of basic blocks that were removed. */
73 static int num_removed_blocks;
75 /* True if life data ok at present. */
76 static bool life_data_ok;
78 /* The post-dominator relation on the original block numbers. */
79 static sbitmap *post_dominators;
81 /* Forward references. */
82 static int count_bb_insns PARAMS ((basic_block));
83 static rtx first_active_insn PARAMS ((basic_block));
84 static int last_active_insn_p PARAMS ((basic_block, rtx));
85 static int seq_contains_jump PARAMS ((rtx));
87 static int cond_exec_process_insns PARAMS ((rtx, rtx, rtx, rtx, int));
88 static rtx cond_exec_get_condition PARAMS ((rtx));
89 static int cond_exec_process_if_block PARAMS ((basic_block, basic_block,
90 basic_block, basic_block));
92 static rtx noce_get_condition PARAMS ((rtx, rtx *));
93 static int noce_operand_ok PARAMS ((rtx));
94 static int noce_process_if_block PARAMS ((basic_block, basic_block,
95 basic_block, basic_block));
97 static int process_if_block PARAMS ((basic_block, basic_block,
98 basic_block, basic_block));
99 static void merge_if_block PARAMS ((basic_block, basic_block,
100 basic_block, basic_block));
102 static int find_if_header PARAMS ((basic_block));
103 static int find_if_block PARAMS ((basic_block, edge, edge));
104 static int find_if_case_1 PARAMS ((basic_block, edge, edge));
105 static int find_if_case_2 PARAMS ((basic_block, edge, edge));
106 static int find_cond_trap PARAMS ((basic_block, edge, edge));
107 static int find_memory PARAMS ((rtx *, void *));
108 static int dead_or_predicable PARAMS ((basic_block, basic_block,
109 basic_block, rtx, int));
110 static void noce_emit_move_insn PARAMS ((rtx, rtx));
112 /* Abuse the basic_block AUX field to store the original block index,
113 as well as a flag indicating that the block should be rescaned for
116 #define SET_ORIG_INDEX(BB,I) ((BB)->aux = (void *)((size_t)(I) << 1))
117 #define ORIG_INDEX(BB) ((size_t)(BB)->aux >> 1)
118 #define SET_UPDATE_LIFE(BB) ((BB)->aux = (void *)((size_t)(BB)->aux | 1))
119 #define UPDATE_LIFE(BB) ((size_t)(BB)->aux & 1)
122 /* Count the number of non-jump active insns in BB. */
133 if (GET_CODE (insn) == CALL_INSN || GET_CODE (insn) == INSN)
138 insn = NEXT_INSN (insn);
144 /* Return the first non-jump active insn in the basic block. */
147 first_active_insn (bb)
152 if (GET_CODE (insn) == CODE_LABEL)
156 insn = NEXT_INSN (insn);
159 while (GET_CODE (insn) == NOTE)
163 insn = NEXT_INSN (insn);
166 if (GET_CODE (insn) == JUMP_INSN)
172 /* Return true if INSN is the last active non-jump insn in BB. */
175 last_active_insn_p (bb, insn)
183 insn = NEXT_INSN (insn);
185 while (GET_CODE (insn) == NOTE);
187 return GET_CODE (insn) == JUMP_INSN;
190 /* It is possible, especially when having dealt with multi-word
191 arithmetic, for the expanders to have emitted jumps. Search
192 through the sequence and return TRUE if a jump exists so that
193 we can abort the conversion. */
196 seq_contains_jump (insn)
201 if (GET_CODE (insn) == JUMP_INSN)
203 insn = NEXT_INSN (insn);
208 /* Go through a bunch of insns, converting them to conditional
209 execution format if possible. Return TRUE if all of the non-note
210 insns were processed. */
213 cond_exec_process_insns (start, end, test, prob_val, mod_ok)
214 rtx start; /* first insn to look at */
215 rtx end; /* last insn to look at */
216 rtx test; /* conditional execution test */
217 rtx prob_val; /* probability of branch taken. */
218 int mod_ok; /* true if modifications ok last insn. */
220 int must_be_last = FALSE;
224 for (insn = start; ; insn = NEXT_INSN (insn))
226 if (GET_CODE (insn) == NOTE)
229 if (GET_CODE (insn) != INSN && GET_CODE (insn) != CALL_INSN)
232 /* Remove USE insns that get in the way. */
233 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
235 /* ??? Ug. Actually unlinking the thing is problematic,
236 given what we'd have to coordinate with our callers. */
237 PUT_CODE (insn, NOTE);
238 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
239 NOTE_SOURCE_FILE (insn) = 0;
243 /* Last insn wasn't last? */
247 if (modified_in_p (test, insn))
254 /* Now build the conditional form of the instruction. */
255 pattern = PATTERN (insn);
257 /* If the machine needs to modify the insn being conditionally executed,
258 say for example to force a constant integer operand into a temp
259 register, do so here. */
260 #ifdef IFCVT_MODIFY_INSN
261 IFCVT_MODIFY_INSN (pattern, insn);
266 validate_change (insn, &PATTERN (insn),
267 gen_rtx_COND_EXEC (VOIDmode, copy_rtx (test),
270 if (GET_CODE (insn) == CALL_INSN && prob_val)
271 validate_change (insn, ®_NOTES (insn),
272 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
273 REG_NOTES (insn)), 1);
283 /* Return the condition for a jump. Do not do any special processing. */
286 cond_exec_get_condition (jump)
291 if (any_condjump_p (jump))
292 test_if = SET_SRC (pc_set (jump));
295 cond = XEXP (test_if, 0);
297 /* If this branches to JUMP_LABEL when the condition is false,
298 reverse the condition. */
299 if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF
300 && XEXP (XEXP (test_if, 2), 0) == JUMP_LABEL (jump))
302 enum rtx_code rev = reversed_comparison_code (cond, jump);
306 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
313 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
314 to conditional execution. Return TRUE if we were successful at
315 converting the the block. */
318 cond_exec_process_if_block (test_bb, then_bb, else_bb, join_bb)
319 basic_block test_bb; /* Basic block test is in */
320 basic_block then_bb; /* Basic block for THEN block */
321 basic_block else_bb; /* Basic block for ELSE block */
322 basic_block join_bb; /* Basic block the join label is in */
324 rtx test_expr; /* expression in IF_THEN_ELSE that is tested */
325 rtx then_start; /* first insn in THEN block */
326 rtx then_end; /* last insn + 1 in THEN block */
327 rtx else_start = NULL_RTX; /* first insn in ELSE block or NULL */
328 rtx else_end = NULL_RTX; /* last insn + 1 in ELSE block */
329 int max; /* max # of insns to convert. */
330 int then_mod_ok; /* whether conditional mods are ok in THEN */
331 rtx true_expr; /* test for else block insns */
332 rtx false_expr; /* test for then block insns */
333 rtx true_prob_val; /* probability of else block */
334 rtx false_prob_val; /* probability of then block */
336 enum rtx_code false_code;
338 /* Find the conditional jump to the ELSE or JOIN part, and isolate
340 test_expr = cond_exec_get_condition (test_bb->end);
344 /* If the conditional jump is more than just a conditional jump,
345 then we can not do conditional execution conversion on this block. */
346 if (!onlyjump_p (test_bb->end))
349 /* Collect the bounds of where we're to search. */
351 then_start = then_bb->head;
352 then_end = then_bb->end;
354 /* Skip a label heading THEN block. */
355 if (GET_CODE (then_start) == CODE_LABEL)
356 then_start = NEXT_INSN (then_start);
358 /* Skip a (use (const_int 0)) or branch as the final insn. */
359 if (GET_CODE (then_end) == INSN
360 && GET_CODE (PATTERN (then_end)) == USE
361 && GET_CODE (XEXP (PATTERN (then_end), 0)) == CONST_INT)
362 then_end = PREV_INSN (then_end);
363 else if (GET_CODE (then_end) == JUMP_INSN)
364 then_end = PREV_INSN (then_end);
368 /* Skip the ELSE block's label. */
369 else_start = NEXT_INSN (else_bb->head);
370 else_end = else_bb->end;
372 /* Skip a (use (const_int 0)) or branch as the final insn. */
373 if (GET_CODE (else_end) == INSN
374 && GET_CODE (PATTERN (else_end)) == USE
375 && GET_CODE (XEXP (PATTERN (else_end), 0)) == CONST_INT)
376 else_end = PREV_INSN (else_end);
377 else if (GET_CODE (else_end) == JUMP_INSN)
378 else_end = PREV_INSN (else_end);
381 /* How many instructions should we convert in total? */
385 max = 2 * MAX_CONDITIONAL_EXECUTE;
386 n_insns = count_bb_insns (else_bb);
389 max = MAX_CONDITIONAL_EXECUTE;
390 n_insns += count_bb_insns (then_bb);
394 /* Map test_expr/test_jump into the appropriate MD tests to use on
395 the conditionally executed code. */
397 true_expr = test_expr;
399 false_code = reversed_comparison_code (true_expr, test_bb->end);
400 if (false_code != UNKNOWN)
401 false_expr = gen_rtx_fmt_ee (false_code, GET_MODE (true_expr),
402 XEXP (true_expr, 0), XEXP (true_expr, 1));
404 false_expr = NULL_RTX;
406 #ifdef IFCVT_MODIFY_TESTS
407 /* If the machine description needs to modify the tests, such as setting a
408 conditional execution register from a comparison, it can do so here. */
409 IFCVT_MODIFY_TESTS (true_expr, false_expr, test_bb, then_bb, else_bb,
412 /* See if the conversion failed */
413 if (!true_expr || !false_expr)
417 true_prob_val = find_reg_note (test_bb->end, REG_BR_PROB, NULL_RTX);
420 true_prob_val = XEXP (true_prob_val, 0);
421 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
424 false_prob_val = NULL_RTX;
426 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
427 on then THEN block. */
428 then_mod_ok = (else_bb == NULL_BLOCK);
430 /* Go through the THEN and ELSE blocks converting the insns if possible
431 to conditional execution. */
435 || ! cond_exec_process_insns (then_start, then_end, false_expr,
436 false_prob_val, then_mod_ok)))
440 && ! cond_exec_process_insns (else_start, else_end,
441 true_expr, true_prob_val, TRUE))
444 if (! apply_change_group ())
447 #ifdef IFCVT_MODIFY_FINAL
448 /* Do any machine dependent final modifications */
449 IFCVT_MODIFY_FINAL (test_bb, then_bb, else_bb, join_bb);
452 /* Conversion succeeded. */
454 fprintf (rtl_dump_file, "%d insn%s converted to conditional execution.\n",
455 n_insns, (n_insns == 1) ? " was" : "s were");
457 /* Merge the blocks! */
458 merge_if_block (test_bb, then_bb, else_bb, join_bb);
462 #ifdef IFCVT_MODIFY_CANCEL
463 /* Cancel any machine dependent changes. */
464 IFCVT_MODIFY_CANCEL (test_bb, then_bb, else_bb, join_bb);
471 /* Used by noce_process_if_block to communicate with its subroutines.
473 The subroutines know that A and B may be evaluated freely. They
474 know that X is a register. They should insert new instructions
475 before cond_earliest. */
482 rtx jump, cond, cond_earliest;
485 static rtx noce_emit_store_flag PARAMS ((struct noce_if_info *,
487 static int noce_try_store_flag PARAMS ((struct noce_if_info *));
488 static int noce_try_store_flag_inc PARAMS ((struct noce_if_info *));
489 static int noce_try_store_flag_constants PARAMS ((struct noce_if_info *));
490 static int noce_try_store_flag_mask PARAMS ((struct noce_if_info *));
491 static rtx noce_emit_cmove PARAMS ((struct noce_if_info *,
492 rtx, enum rtx_code, rtx,
494 static int noce_try_cmove PARAMS ((struct noce_if_info *));
495 static int noce_try_cmove_arith PARAMS ((struct noce_if_info *));
496 static rtx noce_get_alt_condition PARAMS ((struct noce_if_info *,
498 static int noce_try_minmax PARAMS ((struct noce_if_info *));
499 static int noce_try_abs PARAMS ((struct noce_if_info *));
501 /* Helper function for noce_try_store_flag*. */
504 noce_emit_store_flag (if_info, x, reversep, normalize)
505 struct noce_if_info *if_info;
507 int reversep, normalize;
509 rtx cond = if_info->cond;
513 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
514 || ! general_operand (XEXP (cond, 1), VOIDmode));
516 /* If earliest == jump, or when the condition is complex, try to
517 build the store_flag insn directly. */
520 cond = XEXP (SET_SRC (pc_set (if_info->jump)), 0);
523 code = reversed_comparison_code (cond, if_info->jump);
525 code = GET_CODE (cond);
527 if ((if_info->cond_earliest == if_info->jump || cond_complex)
528 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
532 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
534 tmp = gen_rtx_SET (VOIDmode, x, tmp);
537 tmp = emit_insn (tmp);
539 if (recog_memoized (tmp) >= 0)
545 if_info->cond_earliest = if_info->jump;
553 /* Don't even try if the comparison operands are weird. */
557 return emit_store_flag (x, code, XEXP (cond, 0),
558 XEXP (cond, 1), VOIDmode,
559 (code == LTU || code == LEU
560 || code == GEU || code == GTU), normalize);
563 /* Emit instruction to move a rtx into STRICT_LOW_PART. */
565 noce_emit_move_insn (x, y)
568 enum machine_mode outmode, inmode;
572 if (GET_CODE (x) != STRICT_LOW_PART)
574 emit_move_insn (x, y);
579 inner = XEXP (outer, 0);
580 outmode = GET_MODE (outer);
581 inmode = GET_MODE (inner);
582 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
583 store_bit_field (inner, GET_MODE_BITSIZE (outmode),
584 bitpos, outmode, y, GET_MODE_BITSIZE (inmode),
585 GET_MODE_BITSIZE (inmode));
588 /* Convert "if (test) x = 1; else x = 0".
590 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
591 tried in noce_try_store_flag_constants after noce_try_cmove has had
592 a go at the conversion. */
595 noce_try_store_flag (if_info)
596 struct noce_if_info *if_info;
601 if (GET_CODE (if_info->b) == CONST_INT
602 && INTVAL (if_info->b) == STORE_FLAG_VALUE
603 && if_info->a == const0_rtx)
605 else if (if_info->b == const0_rtx
606 && GET_CODE (if_info->a) == CONST_INT
607 && INTVAL (if_info->a) == STORE_FLAG_VALUE
608 && (reversed_comparison_code (if_info->cond, if_info->jump)
616 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
619 if (target != if_info->x)
620 noce_emit_move_insn (if_info->x, target);
624 emit_insns_before (seq, if_info->cond_earliest);
635 /* Convert "if (test) x = a; else x = b", for A and B constant. */
638 noce_try_store_flag_constants (if_info)
639 struct noce_if_info *if_info;
643 HOST_WIDE_INT itrue, ifalse, diff, tmp;
644 int normalize, can_reverse;
645 enum machine_mode mode;
648 && GET_CODE (if_info->a) == CONST_INT
649 && GET_CODE (if_info->b) == CONST_INT)
651 mode = GET_MODE (if_info->x);
652 ifalse = INTVAL (if_info->a);
653 itrue = INTVAL (if_info->b);
654 diff = trunc_int_for_mode (mode, itrue - ifalse);
656 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
660 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
662 else if (ifalse == 0 && exact_log2 (itrue) >= 0
663 && (STORE_FLAG_VALUE == 1
664 || BRANCH_COST >= 2))
666 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
667 && (STORE_FLAG_VALUE == 1 || BRANCH_COST >= 2))
668 normalize = 1, reversep = 1;
670 && (STORE_FLAG_VALUE == -1
671 || BRANCH_COST >= 2))
673 else if (ifalse == -1 && can_reverse
674 && (STORE_FLAG_VALUE == -1 || BRANCH_COST >= 2))
675 normalize = -1, reversep = 1;
676 else if ((BRANCH_COST >= 2 && STORE_FLAG_VALUE == -1)
684 tmp = itrue; itrue = ifalse; ifalse = tmp;
685 diff = trunc_int_for_mode (mode, -diff);
689 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
696 /* if (test) x = 3; else x = 4;
697 => x = 3 + (test == 0); */
698 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
700 target = expand_binop (mode,
701 (diff == STORE_FLAG_VALUE
702 ? add_optab : sub_optab),
703 GEN_INT (ifalse), target, if_info->x, 0,
707 /* if (test) x = 8; else x = 0;
708 => x = (test != 0) << 3; */
709 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
711 target = expand_binop (mode, ashl_optab,
712 target, GEN_INT (tmp), if_info->x, 0,
716 /* if (test) x = -1; else x = b;
717 => x = -(test != 0) | b; */
718 else if (itrue == -1)
720 target = expand_binop (mode, ior_optab,
721 target, GEN_INT (ifalse), if_info->x, 0,
725 /* if (test) x = a; else x = b;
726 => x = (-(test != 0) & (b - a)) + a; */
729 target = expand_binop (mode, and_optab,
730 target, GEN_INT (diff), if_info->x, 0,
733 target = expand_binop (mode, add_optab,
734 target, GEN_INT (ifalse), if_info->x, 0,
744 if (target != if_info->x)
745 noce_emit_move_insn (if_info->x, target);
750 if (seq_contains_jump (seq))
753 emit_insns_before (seq, if_info->cond_earliest);
761 /* Convert "if (test) foo++" into "foo += (test != 0)", and
762 similarly for "foo--". */
765 noce_try_store_flag_inc (if_info)
766 struct noce_if_info *if_info;
769 int subtract, normalize;
775 /* Should be no `else' case to worry about. */
776 && if_info->b == if_info->x
777 && GET_CODE (if_info->a) == PLUS
778 && (XEXP (if_info->a, 1) == const1_rtx
779 || XEXP (if_info->a, 1) == constm1_rtx)
780 && rtx_equal_p (XEXP (if_info->a, 0), if_info->x)
781 && (reversed_comparison_code (if_info->cond, if_info->jump)
784 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
785 subtract = 0, normalize = 0;
786 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
787 subtract = 1, normalize = 0;
789 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
793 target = noce_emit_store_flag (if_info,
794 gen_reg_rtx (GET_MODE (if_info->x)),
798 target = expand_binop (GET_MODE (if_info->x),
799 subtract ? sub_optab : add_optab,
800 if_info->x, target, if_info->x, 0, OPTAB_WIDEN);
803 if (target != if_info->x)
804 noce_emit_move_insn (if_info->x, target);
809 if (seq_contains_jump (seq))
812 emit_insns_before (seq, if_info->cond_earliest);
823 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
826 noce_try_store_flag_mask (if_info)
827 struct noce_if_info *if_info;
835 || STORE_FLAG_VALUE == -1)
836 && ((if_info->a == const0_rtx
837 && rtx_equal_p (if_info->b, if_info->x))
838 || ((reversep = (reversed_comparison_code (if_info->cond,
841 && if_info->b == const0_rtx
842 && rtx_equal_p (if_info->a, if_info->x))))
845 target = noce_emit_store_flag (if_info,
846 gen_reg_rtx (GET_MODE (if_info->x)),
849 target = expand_binop (GET_MODE (if_info->x), and_optab,
850 if_info->x, target, if_info->x, 0,
855 if (target != if_info->x)
856 noce_emit_move_insn (if_info->x, target);
861 if (seq_contains_jump (seq))
864 emit_insns_before (seq, if_info->cond_earliest);
875 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
878 noce_emit_cmove (if_info, x, code, cmp_a, cmp_b, vfalse, vtrue)
879 struct noce_if_info *if_info;
880 rtx x, cmp_a, cmp_b, vfalse, vtrue;
883 /* If earliest == jump, try to build the cmove insn directly.
884 This is helpful when combine has created some complex condition
885 (like for alpha's cmovlbs) that we can't hope to regenerate
886 through the normal interface. */
888 if (if_info->cond_earliest == if_info->jump)
892 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
893 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
894 tmp = gen_rtx_SET (VOIDmode, x, tmp);
897 tmp = emit_insn (tmp);
899 if (recog_memoized (tmp) >= 0)
911 /* Don't even try if the comparison operands are weird. */
912 if (! general_operand (cmp_a, GET_MODE (cmp_a))
913 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
916 #if HAVE_conditional_move
917 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
918 vtrue, vfalse, GET_MODE (x),
919 (code == LTU || code == GEU
920 || code == LEU || code == GTU));
922 /* We'll never get here, as noce_process_if_block doesn't call the
923 functions involved. Ifdef code, however, should be discouraged
924 because it leads to typos in the code not selected. However,
925 emit_conditional_move won't exist either. */
930 /* Try only simple constants and registers here. More complex cases
931 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
932 has had a go at it. */
935 noce_try_cmove (if_info)
936 struct noce_if_info *if_info;
941 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
942 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
946 code = GET_CODE (if_info->cond);
947 target = noce_emit_cmove (if_info, if_info->x, code,
948 XEXP (if_info->cond, 0),
949 XEXP (if_info->cond, 1),
950 if_info->a, if_info->b);
954 if (target != if_info->x)
955 noce_emit_move_insn (if_info->x, target);
959 emit_insns_before (seq, if_info->cond_earliest);
972 /* Try more complex cases involving conditional_move. */
975 noce_try_cmove_arith (if_info)
976 struct noce_if_info *if_info;
986 /* A conditional move from two memory sources is equivalent to a
987 conditional on their addresses followed by a load. Don't do this
988 early because it'll screw alias analysis. Note that we've
989 already checked for no side effects. */
990 if (! no_new_pseudos && cse_not_expected
991 && GET_CODE (a) == MEM && GET_CODE (b) == MEM
996 x = gen_reg_rtx (Pmode);
1000 /* ??? We could handle this if we knew that a load from A or B could
1001 not fault. This is also true if we've already loaded
1002 from the address along the path from ENTRY. */
1003 else if (may_trap_p (a) || may_trap_p (b))
1006 /* if (test) x = a + b; else x = c - d;
1013 code = GET_CODE (if_info->cond);
1014 insn_a = if_info->insn_a;
1015 insn_b = if_info->insn_b;
1017 /* Possibly rearrange operands to make things come out more natural. */
1018 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1021 if (rtx_equal_p (b, x))
1023 else if (general_operand (b, GET_MODE (b)))
1028 code = reversed_comparison_code (if_info->cond, if_info->jump);
1029 tmp = a, a = b, b = tmp;
1030 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1036 /* If either operand is complex, load it into a register first.
1037 The best way to do this is to copy the original insn. In this
1038 way we preserve any clobbers etc that the insn may have had.
1039 This is of course not possible in the IS_MEM case. */
1040 if (! general_operand (a, GET_MODE (a)))
1045 goto end_seq_and_fail;
1049 tmp = gen_reg_rtx (GET_MODE (a));
1050 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1053 goto end_seq_and_fail;
1056 a = gen_reg_rtx (GET_MODE (a));
1057 tmp = copy_rtx (insn_a);
1058 set = single_set (tmp);
1060 tmp = emit_insn (PATTERN (tmp));
1062 if (recog_memoized (tmp) < 0)
1063 goto end_seq_and_fail;
1065 if (! general_operand (b, GET_MODE (b)))
1070 goto end_seq_and_fail;
1074 tmp = gen_reg_rtx (GET_MODE (b));
1075 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, b));
1078 goto end_seq_and_fail;
1081 b = gen_reg_rtx (GET_MODE (b));
1082 tmp = copy_rtx (insn_b);
1083 set = single_set (tmp);
1085 tmp = emit_insn (PATTERN (tmp));
1087 if (recog_memoized (tmp) < 0)
1088 goto end_seq_and_fail;
1091 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1092 XEXP (if_info->cond, 1), a, b);
1095 goto end_seq_and_fail;
1097 /* If we're handling a memory for above, emit the load now. */
1100 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1102 /* Copy over flags as appropriate. */
1103 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1104 MEM_VOLATILE_P (tmp) = 1;
1105 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1106 MEM_IN_STRUCT_P (tmp) = 1;
1107 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1108 MEM_SCALAR_P (tmp) = 1;
1109 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1110 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1112 noce_emit_move_insn (if_info->x, tmp);
1114 else if (target != x)
1115 noce_emit_move_insn (x, target);
1119 emit_insns_before (tmp, if_info->cond_earliest);
1127 /* For most cases, the simplified condition we found is the best
1128 choice, but this is not the case for the min/max/abs transforms.
1129 For these we wish to know that it is A or B in the condition. */
1132 noce_get_alt_condition (if_info, target, earliest)
1133 struct noce_if_info *if_info;
1137 rtx cond, set, insn;
1140 /* If target is already mentioned in the known condition, return it. */
1141 if (reg_mentioned_p (target, if_info->cond))
1143 *earliest = if_info->cond_earliest;
1144 return if_info->cond;
1147 set = pc_set (if_info->jump);
1148 cond = XEXP (SET_SRC (set), 0);
1150 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1151 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1153 cond = canonicalize_condition (if_info->jump, cond, reverse,
1155 if (! cond || ! reg_mentioned_p (target, cond))
1158 /* We almost certainly searched back to a different place.
1159 Need to re-verify correct lifetimes. */
1161 /* X may not be mentioned in the range (cond_earliest, jump]. */
1162 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1163 if (INSN_P (insn) && reg_mentioned_p (if_info->x, insn))
1166 /* A and B may not be modified in the range [cond_earliest, jump). */
1167 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1169 && (modified_in_p (if_info->a, insn)
1170 || modified_in_p (if_info->b, insn)))
1176 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1179 noce_try_minmax (if_info)
1180 struct noce_if_info *if_info;
1182 rtx cond, earliest, target, seq;
1187 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1191 /* ??? Reject FP modes since we don't know how 0 vs -0 or NaNs
1192 will be resolved with an SMIN/SMAX. It wouldn't be too hard
1193 to get the target to tell us... */
1194 if (FLOAT_MODE_P (GET_MODE (if_info->x))
1195 && TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
1196 && ! flag_unsafe_math_optimizations)
1199 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1203 /* Verify the condition is of the form we expect, and canonicalize
1204 the comparison code. */
1205 code = GET_CODE (cond);
1206 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1208 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1211 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1213 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1215 code = swap_condition (code);
1220 /* Determine what sort of operation this is. Note that the code is for
1221 a taken branch, so the code->operation mapping appears backwards. */
1254 target = expand_binop (GET_MODE (if_info->x), op, if_info->a, if_info->b,
1255 if_info->x, unsignedp, OPTAB_WIDEN);
1261 if (target != if_info->x)
1262 noce_emit_move_insn (if_info->x, target);
1267 if (seq_contains_jump (seq))
1270 emit_insns_before (seq, earliest);
1271 if_info->cond = cond;
1272 if_info->cond_earliest = earliest;
1277 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1280 noce_try_abs (if_info)
1281 struct noce_if_info *if_info;
1283 rtx cond, earliest, target, seq, a, b, c;
1286 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1290 /* Recognize A and B as constituting an ABS or NABS. */
1293 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1295 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1297 c = a; a = b; b = c;
1303 cond = noce_get_alt_condition (if_info, b, &earliest);
1307 /* Verify the condition is of the form we expect. */
1308 if (rtx_equal_p (XEXP (cond, 0), b))
1310 else if (rtx_equal_p (XEXP (cond, 1), b))
1315 /* Verify that C is zero. Search backward through the block for
1316 a REG_EQUAL note if necessary. */
1319 rtx insn, note = NULL;
1320 for (insn = earliest;
1321 insn != if_info->test_bb->head;
1322 insn = PREV_INSN (insn))
1324 && ((note = find_reg_note (insn, REG_EQUAL, c))
1325 || (note = find_reg_note (insn, REG_EQUIV, c))))
1331 if (GET_CODE (c) == MEM
1332 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1333 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1334 c = get_pool_constant (XEXP (c, 0));
1336 /* Work around funny ideas get_condition has wrt canonicalization.
1337 Note that these rtx constants are known to be CONST_INT, and
1338 therefore imply integer comparisons. */
1339 if (c == constm1_rtx && GET_CODE (cond) == GT)
1341 else if (c == const1_rtx && GET_CODE (cond) == LT)
1343 else if (c != CONST0_RTX (GET_MODE (b)))
1346 /* Determine what sort of operation this is. */
1347 switch (GET_CODE (cond))
1366 target = expand_unop (GET_MODE (if_info->x), abs_optab, b, if_info->x, 0);
1368 /* ??? It's a quandry whether cmove would be better here, especially
1369 for integers. Perhaps combine will clean things up. */
1370 if (target && negate)
1371 target = expand_unop (GET_MODE (target), neg_optab, target, if_info->x, 0);
1379 if (target != if_info->x)
1380 noce_emit_move_insn (if_info->x, target);
1385 if (seq_contains_jump (seq))
1388 emit_insns_before (seq, earliest);
1389 if_info->cond = cond;
1390 if_info->cond_earliest = earliest;
1395 /* Look for the condition for the jump first. We'd prefer to avoid
1396 get_condition if we can -- it tries to look back for the contents
1397 of an original compare. On targets that use normal integers for
1398 comparisons, e.g. alpha, this is wasteful. */
1401 noce_get_condition (jump, earliest)
1408 /* If the condition variable is a register and is MODE_INT, accept it.
1409 Otherwise, fall back on get_condition. */
1411 if (! any_condjump_p (jump))
1414 set = pc_set (jump);
1416 cond = XEXP (SET_SRC (set), 0);
1417 if (GET_CODE (XEXP (cond, 0)) == REG
1418 && GET_MODE_CLASS (GET_MODE (XEXP (cond, 0))) == MODE_INT)
1422 /* If this branches to JUMP_LABEL when the condition is false,
1423 reverse the condition. */
1424 if (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1425 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump))
1426 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
1427 GET_MODE (cond), XEXP (cond, 0),
1431 cond = get_condition (jump, earliest);
1436 /* Return true if OP is ok for if-then-else processing. */
1439 noce_operand_ok (op)
1442 /* We special-case memories, so handle any of them with
1443 no address side effects. */
1444 if (GET_CODE (op) == MEM)
1445 return ! side_effects_p (XEXP (op, 0));
1447 if (side_effects_p (op))
1450 /* ??? Unfortuantely may_trap_p can't look at flag_trapping_math, due to
1451 being linked into the genfoo programs. This is probably a mistake.
1452 With finite operands, most fp operations don't trap. */
1453 if (!flag_trapping_math && FLOAT_MODE_P (GET_MODE (op)))
1454 switch (GET_CODE (op))
1460 /* ??? This is kinda lame -- almost every target will have forced
1461 the constant into a register first. But given the expense of
1462 division, this is probably for the best. */
1463 return (CONSTANT_P (XEXP (op, 1))
1464 && XEXP (op, 1) != CONST0_RTX (GET_MODE (op))
1465 && ! may_trap_p (XEXP (op, 0)));
1468 switch (GET_RTX_CLASS (GET_CODE (op)))
1471 return ! may_trap_p (XEXP (op, 0));
1474 return ! may_trap_p (XEXP (op, 0)) && ! may_trap_p (XEXP (op, 1));
1479 return ! may_trap_p (op);
1482 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1483 without using conditional execution. Return TRUE if we were
1484 successful at converting the the block. */
1487 noce_process_if_block (test_bb, then_bb, else_bb, join_bb)
1488 basic_block test_bb; /* Basic block test is in */
1489 basic_block then_bb; /* Basic block for THEN block */
1490 basic_block else_bb; /* Basic block for ELSE block */
1491 basic_block join_bb; /* Basic block the join label is in */
1493 /* We're looking for patterns of the form
1495 (1) if (...) x = a; else x = b;
1496 (2) x = b; if (...) x = a;
1497 (3) if (...) x = a; // as if with an initial x = x.
1499 The later patterns require jumps to be more expensive.
1501 ??? For future expansion, look for multiple X in such patterns. */
1503 struct noce_if_info if_info;
1506 rtx orig_x, x, a, b;
1507 rtx jump, cond, insn;
1509 /* If this is not a standard conditional jump, we can't parse it. */
1510 jump = test_bb->end;
1511 cond = noce_get_condition (jump, &if_info.cond_earliest);
1515 /* If the conditional jump is more than just a conditional jump,
1516 then we can not do if-conversion on this block. */
1517 if (! onlyjump_p (jump))
1520 /* We must be comparing objects whose modes imply the size. */
1521 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
1524 /* Look for one of the potential sets. */
1525 insn_a = first_active_insn (then_bb);
1527 || ! last_active_insn_p (then_bb, insn_a)
1528 || (set_a = single_set (insn_a)) == NULL_RTX)
1531 x = SET_DEST (set_a);
1532 a = SET_SRC (set_a);
1534 /* Look for the other potential set. Make sure we've got equivalent
1536 /* ??? This is overconservative. Storing to two different mems is
1537 as easy as conditionally computing the address. Storing to a
1538 single mem merely requires a scratch memory to use as one of the
1539 destination addresses; often the memory immediately below the
1540 stack pointer is available for this. */
1544 insn_b = first_active_insn (else_bb);
1546 || ! last_active_insn_p (else_bb, insn_b)
1547 || (set_b = single_set (insn_b)) == NULL_RTX
1548 || ! rtx_equal_p (x, SET_DEST (set_b)))
1553 insn_b = prev_nonnote_insn (if_info.cond_earliest);
1555 || GET_CODE (insn_b) != INSN
1556 || (set_b = single_set (insn_b)) == NULL_RTX
1557 || ! rtx_equal_p (x, SET_DEST (set_b))
1558 || reg_mentioned_p (x, cond)
1559 || reg_mentioned_p (x, a)
1560 || reg_mentioned_p (x, SET_SRC (set_b)))
1561 insn_b = set_b = NULL_RTX;
1563 b = (set_b ? SET_SRC (set_b) : x);
1565 /* X may not be mentioned in the range (cond_earliest, jump]. */
1566 for (insn = jump; insn != if_info.cond_earliest; insn = PREV_INSN (insn))
1567 if (INSN_P (insn) && reg_mentioned_p (x, insn))
1570 /* A and B may not be modified in the range [cond_earliest, jump). */
1571 for (insn = if_info.cond_earliest; insn != jump; insn = NEXT_INSN (insn))
1573 && (modified_in_p (a, insn) || modified_in_p (b, insn)))
1576 /* Only operate on register destinations, and even then avoid extending
1577 the lifetime of hard registers on small register class machines. */
1579 if (GET_CODE (x) != REG
1580 || (SMALL_REGISTER_CLASSES
1581 && REGNO (x) < FIRST_PSEUDO_REGISTER))
1585 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
1586 ? XEXP (x, 0) : x));
1589 /* Don't operate on sources that may trap or are volatile. */
1590 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
1593 /* Set up the info block for our subroutines. */
1594 if_info.test_bb = test_bb;
1595 if_info.cond = cond;
1596 if_info.jump = jump;
1597 if_info.insn_a = insn_a;
1598 if_info.insn_b = insn_b;
1603 /* Try optimizations in some approximation of a useful order. */
1604 /* ??? Should first look to see if X is live incoming at all. If it
1605 isn't, we don't need anything but an unconditional set. */
1607 /* Look and see if A and B are really the same. Avoid creating silly
1608 cmove constructs that no one will fix up later. */
1609 if (rtx_equal_p (a, b))
1611 /* If we have an INSN_B, we don't have to create any new rtl. Just
1612 move the instruction that we already have. If we don't have an
1613 INSN_B, that means that A == X, and we've got a noop move. In
1614 that case don't do anything and let the code below delete INSN_A. */
1615 if (insn_b && else_bb)
1619 if (else_bb && insn_b == else_bb->end)
1620 else_bb->end = PREV_INSN (insn_b);
1621 reorder_insns (insn_b, insn_b, PREV_INSN (if_info.cond_earliest));
1623 /* If there was a REG_EQUAL note, delete it since it may have been
1624 true due to this insn being after a jump. */
1625 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
1626 remove_note (insn_b, note);
1630 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
1631 x must be executed twice. */
1632 else if (insn_b && side_effects_p (orig_x))
1639 if (noce_try_store_flag (&if_info))
1641 if (noce_try_minmax (&if_info))
1643 if (noce_try_abs (&if_info))
1645 if (HAVE_conditional_move
1646 && noce_try_cmove (&if_info))
1648 if (! HAVE_conditional_execution)
1650 if (noce_try_store_flag_constants (&if_info))
1652 if (noce_try_store_flag_inc (&if_info))
1654 if (noce_try_store_flag_mask (&if_info))
1656 if (HAVE_conditional_move
1657 && noce_try_cmove_arith (&if_info))
1664 /* The original sets may now be killed. */
1665 if (insn_a == then_bb->end)
1666 then_bb->end = PREV_INSN (insn_a);
1667 flow_delete_insn (insn_a);
1669 /* Several special cases here: First, we may have reused insn_b above,
1670 in which case insn_b is now NULL. Second, we want to delete insn_b
1671 if it came from the ELSE block, because follows the now correct
1672 write that appears in the TEST block. However, if we got insn_b from
1673 the TEST block, it may in fact be loading data needed for the comparison.
1674 We'll let life_analysis remove the insn if it's really dead. */
1675 if (insn_b && else_bb)
1677 if (insn_b == else_bb->end)
1678 else_bb->end = PREV_INSN (insn_b);
1679 flow_delete_insn (insn_b);
1682 /* The new insns will have been inserted before cond_earliest. We should
1683 be able to remove the jump with impunity, but the condition itself may
1684 have been modified by gcse to be shared across basic blocks. */
1685 test_bb->end = PREV_INSN (jump);
1686 flow_delete_insn (jump);
1688 /* If we used a temporary, fix it up now. */
1692 noce_emit_move_insn (orig_x, x);
1693 insn_b = gen_sequence ();
1696 test_bb->end = emit_insn_after (insn_b, test_bb->end);
1699 /* Merge the blocks! */
1700 merge_if_block (test_bb, then_bb, else_bb, join_bb);
1705 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
1706 straight line code. Return true if successful. */
1709 process_if_block (test_bb, then_bb, else_bb, join_bb)
1710 basic_block test_bb; /* Basic block test is in */
1711 basic_block then_bb; /* Basic block for THEN block */
1712 basic_block else_bb; /* Basic block for ELSE block */
1713 basic_block join_bb; /* Basic block the join label is in */
1715 if (! reload_completed
1716 && noce_process_if_block (test_bb, then_bb, else_bb, join_bb))
1719 if (HAVE_conditional_execution
1721 && cond_exec_process_if_block (test_bb, then_bb, else_bb, join_bb))
1727 /* Merge the blocks and mark for local life update. */
1730 merge_if_block (test_bb, then_bb, else_bb, join_bb)
1731 basic_block test_bb; /* Basic block test is in */
1732 basic_block then_bb; /* Basic block for THEN block */
1733 basic_block else_bb; /* Basic block for ELSE block */
1734 basic_block join_bb; /* Basic block the join label is in */
1736 basic_block combo_bb;
1738 /* All block merging is done into the lower block numbers. */
1742 /* First merge TEST block into THEN block. This is a no-brainer since
1743 the THEN block did not have a code label to begin with. */
1746 COPY_REG_SET (combo_bb->global_live_at_end, then_bb->global_live_at_end);
1747 merge_blocks_nomove (combo_bb, then_bb);
1748 num_removed_blocks++;
1750 /* The ELSE block, if it existed, had a label. That label count
1751 will almost always be zero, but odd things can happen when labels
1752 get their addresses taken. */
1755 merge_blocks_nomove (combo_bb, else_bb);
1756 num_removed_blocks++;
1759 /* If there was no join block reported, that means it was not adjacent
1760 to the others, and so we cannot merge them. */
1764 /* The outgoing edge for the current COMBO block should already
1765 be correct. Verify this. */
1766 if (combo_bb->succ == NULL_EDGE)
1769 /* There should still be a branch at the end of the THEN or ELSE
1770 blocks taking us to our final destination. */
1771 if (GET_CODE (combo_bb->end) != JUMP_INSN)
1775 /* The JOIN block may have had quite a number of other predecessors too.
1776 Since we've already merged the TEST, THEN and ELSE blocks, we should
1777 have only one remaining edge from our if-then-else diamond. If there
1778 is more than one remaining edge, it must come from elsewhere. There
1779 may be zero incoming edges if the THEN block didn't actually join
1780 back up (as with a call to abort). */
1781 else if (join_bb->pred == NULL || join_bb->pred->pred_next == NULL)
1783 /* We can merge the JOIN. */
1785 COPY_REG_SET (combo_bb->global_live_at_end,
1786 join_bb->global_live_at_end);
1787 merge_blocks_nomove (combo_bb, join_bb);
1788 num_removed_blocks++;
1792 /* We cannot merge the JOIN. */
1794 /* The outgoing edge for the current COMBO block should already
1795 be correct. Verify this. */
1796 if (combo_bb->succ->succ_next != NULL_EDGE
1797 || combo_bb->succ->dest != join_bb)
1800 /* Remove the jump and cruft from the end of the COMBO block. */
1801 tidy_fallthru_edge (combo_bb->succ, combo_bb, join_bb);
1804 /* Make sure we update life info properly. */
1805 SET_UPDATE_LIFE (combo_bb);
1807 num_updated_if_blocks++;
1810 /* Find a block ending in a simple IF condition. Return TRUE if
1811 we were able to transform it in some way. */
1814 find_if_header (test_bb)
1815 basic_block test_bb;
1820 /* The kind of block we're looking for has exactly two successors. */
1821 if ((then_edge = test_bb->succ) == NULL_EDGE
1822 || (else_edge = then_edge->succ_next) == NULL_EDGE
1823 || else_edge->succ_next != NULL_EDGE)
1826 /* Neither edge should be abnormal. */
1827 if ((then_edge->flags & EDGE_COMPLEX)
1828 || (else_edge->flags & EDGE_COMPLEX))
1831 /* The THEN edge is canonically the one that falls through. */
1832 if (then_edge->flags & EDGE_FALLTHRU)
1834 else if (else_edge->flags & EDGE_FALLTHRU)
1837 else_edge = then_edge;
1841 /* Otherwise this must be a multiway branch of some sort. */
1844 if (find_if_block (test_bb, then_edge, else_edge))
1846 if (HAVE_trap && HAVE_conditional_trap
1847 && find_cond_trap (test_bb, then_edge, else_edge))
1850 && (! HAVE_conditional_execution || reload_completed))
1852 if (find_if_case_1 (test_bb, then_edge, else_edge))
1854 if (find_if_case_2 (test_bb, then_edge, else_edge))
1862 fprintf (rtl_dump_file, "Conversion succeeded.\n");
1866 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
1867 block. If so, we'll try to convert the insns to not require the branch.
1868 Return TRUE if we were successful at converting the the block. */
1871 find_if_block (test_bb, then_edge, else_edge)
1872 basic_block test_bb;
1873 edge then_edge, else_edge;
1875 basic_block then_bb = then_edge->dest;
1876 basic_block else_bb = else_edge->dest;
1877 basic_block join_bb = NULL_BLOCK;
1878 edge then_succ = then_bb->succ;
1879 edge else_succ = else_bb->succ;
1882 /* The THEN block of an IF-THEN combo must have exactly one predecessor. */
1883 if (then_bb->pred->pred_next != NULL_EDGE)
1886 /* The THEN block of an IF-THEN combo must have zero or one successors. */
1887 if (then_succ != NULL_EDGE
1888 && (then_succ->succ_next != NULL_EDGE
1889 || (then_succ->flags & EDGE_COMPLEX)))
1892 /* If the THEN block has no successors, conditional execution can still
1893 make a conditional call. Don't do this unless the ELSE block has
1894 only one incoming edge -- the CFG manipulation is too ugly otherwise.
1895 Check for the last insn of the THEN block being an indirect jump, which
1896 is listed as not having any successors, but confuses the rest of the CE
1897 code processing. XXX we should fix this in the future. */
1898 if (then_succ == NULL)
1900 if (else_bb->pred->pred_next == NULL_EDGE)
1902 rtx last_insn = then_bb->end;
1905 && GET_CODE (last_insn) == NOTE
1906 && last_insn != then_bb->head)
1907 last_insn = PREV_INSN (last_insn);
1910 && GET_CODE (last_insn) == JUMP_INSN
1911 && ! simplejump_p (last_insn))
1915 else_bb = NULL_BLOCK;
1921 /* If the THEN block's successor is the other edge out of the TEST block,
1922 then we have an IF-THEN combo without an ELSE. */
1923 else if (then_succ->dest == else_bb)
1926 else_bb = NULL_BLOCK;
1929 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
1930 has exactly one predecessor and one successor, and the outgoing edge
1931 is not complex, then we have an IF-THEN-ELSE combo. */
1932 else if (else_succ != NULL_EDGE
1933 && then_succ->dest == else_succ->dest
1934 && else_bb->pred->pred_next == NULL_EDGE
1935 && else_succ->succ_next == NULL_EDGE
1936 && ! (else_succ->flags & EDGE_COMPLEX))
1937 join_bb = else_succ->dest;
1939 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
1943 num_possible_if_blocks++;
1948 fprintf (rtl_dump_file,
1949 "\nIF-THEN-ELSE block found, start %d, then %d, else %d, join %d\n",
1950 test_bb->index, then_bb->index, else_bb->index,
1953 fprintf (rtl_dump_file,
1954 "\nIF-THEN block found, start %d, then %d, join %d\n",
1955 test_bb->index, then_bb->index, join_bb->index);
1958 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we
1959 get the first condition for free, since we've already asserted that
1960 there's a fallthru edge from IF to THEN. */
1961 /* ??? As an enhancement, move the ELSE block. Have to deal with
1962 BLOCK notes, if by no other means than aborting the merge if they
1963 exist. Sticky enough I don't want to think about it now. */
1964 next_index = then_bb->index;
1965 if (else_bb && ++next_index != else_bb->index)
1967 if (++next_index != join_bb->index)
1975 /* Do the real work. */
1976 return process_if_block (test_bb, then_bb, else_bb, join_bb);
1979 /* Convert a branch over a trap, or a branch to a trap,
1980 into a conditional trap. */
1983 find_cond_trap (test_bb, then_edge, else_edge)
1984 basic_block test_bb;
1985 edge then_edge, else_edge;
1987 basic_block then_bb, else_bb, join_bb, trap_bb;
1988 rtx trap, jump, cond, cond_earliest, seq;
1991 then_bb = then_edge->dest;
1992 else_bb = else_edge->dest;
1995 /* Locate the block with the trap instruction. */
1996 /* ??? While we look for no successors, we really ought to allow
1997 EH successors. Need to fix merge_if_block for that to work. */
1998 /* ??? We can't currently handle merging the blocks if they are not
1999 already adjacent. Prevent losage in merge_if_block by detecting
2001 if (then_bb->succ == NULL)
2004 if (else_bb->index != then_bb->index + 1)
2009 else if (else_bb->succ == NULL)
2012 if (else_bb->index != then_bb->index + 1)
2014 else if (then_bb->succ
2015 && ! then_bb->succ->succ_next
2016 && ! (then_bb->succ->flags & EDGE_COMPLEX)
2017 && then_bb->succ->dest->index == else_bb->index + 1)
2018 join_bb = then_bb->succ->dest;
2023 /* Don't confuse a conditional return with something we want to
2025 if (trap_bb == EXIT_BLOCK_PTR)
2028 /* The only instruction in the THEN block must be the trap. */
2029 trap = first_active_insn (trap_bb);
2030 if (! (trap == trap_bb->end
2031 && GET_CODE (PATTERN (trap)) == TRAP_IF
2032 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
2037 if (trap_bb == then_bb)
2038 fprintf (rtl_dump_file,
2039 "\nTRAP-IF block found, start %d, trap %d",
2040 test_bb->index, then_bb->index);
2042 fprintf (rtl_dump_file,
2043 "\nTRAP-IF block found, start %d, then %d, trap %d",
2044 test_bb->index, then_bb->index, trap_bb->index);
2046 fprintf (rtl_dump_file, ", join %d\n", join_bb->index);
2048 fputc ('\n', rtl_dump_file);
2051 /* If this is not a standard conditional jump, we can't parse it. */
2052 jump = test_bb->end;
2053 cond = noce_get_condition (jump, &cond_earliest);
2057 /* If the conditional jump is more than just a conditional jump,
2058 then we can not do if-conversion on this block. */
2059 if (! onlyjump_p (jump))
2062 /* We must be comparing objects whose modes imply the size. */
2063 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2066 /* Reverse the comparison code, if necessary. */
2067 code = GET_CODE (cond);
2068 if (then_bb == trap_bb)
2070 code = reversed_comparison_code (cond, jump);
2071 if (code == UNKNOWN)
2075 /* Attempt to generate the conditional trap. */
2076 seq = gen_cond_trap (code, XEXP (cond, 0), XEXP (cond, 1),
2077 TRAP_CODE (PATTERN (trap)));
2081 /* Emit the new insns before cond_earliest; delete the old jump
2084 emit_insn_before (seq, cond_earliest);
2086 test_bb->end = PREV_INSN (jump);
2087 flow_delete_insn (jump);
2089 trap_bb->end = PREV_INSN (trap);
2090 flow_delete_insn (trap);
2092 /* Merge the blocks! */
2093 if (trap_bb != then_bb && ! else_bb)
2095 flow_delete_block (trap_bb);
2096 num_removed_blocks++;
2098 merge_if_block (test_bb, then_bb, else_bb, join_bb);
2103 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2104 transformable, but not necessarily the other. There need be no
2107 Return TRUE if we were successful at converting the the block.
2109 Cases we'd like to look at:
2112 if (test) goto over; // x not live
2120 if (! test) goto label;
2123 if (test) goto E; // x not live
2137 (3) // This one's really only interesting for targets that can do
2138 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2139 // it results in multiple branches on a cache line, which often
2140 // does not sit well with predictors.
2142 if (test1) goto E; // predicted not taken
2158 (A) Don't do (2) if the branch is predicted against the block we're
2159 eliminating. Do it anyway if we can eliminate a branch; this requires
2160 that the sole successor of the eliminated block postdominate the other
2163 (B) With CE, on (3) we can steal from both sides of the if, creating
2172 Again, this is most useful if J postdominates.
2174 (C) CE substitutes for helpful life information.
2176 (D) These heuristics need a lot of work. */
2178 /* Tests for case 1 above. */
2181 find_if_case_1 (test_bb, then_edge, else_edge)
2182 basic_block test_bb;
2183 edge then_edge, else_edge;
2185 basic_block then_bb = then_edge->dest;
2186 basic_block else_bb = else_edge->dest;
2187 edge then_succ = then_bb->succ;
2190 /* THEN has one successor. */
2191 if (!then_succ || then_succ->succ_next != NULL)
2194 /* THEN does not fall through, but is not strange either. */
2195 if (then_succ->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
2198 /* THEN has one predecessor. */
2199 if (then_bb->pred->pred_next != NULL)
2202 /* ELSE follows THEN. (??? could be moved) */
2203 if (else_bb->index != then_bb->index + 1)
2206 num_possible_if_blocks++;
2208 fprintf (rtl_dump_file,
2209 "\nIF-CASE-1 found, start %d, then %d\n",
2210 test_bb->index, then_bb->index);
2212 /* THEN is small. */
2213 if (count_bb_insns (then_bb) > BRANCH_COST)
2216 /* Find the label for THEN's destination. */
2217 if (then_succ->dest == EXIT_BLOCK_PTR)
2221 new_lab = JUMP_LABEL (then_bb->end);
2226 /* Registers set are dead, or are predicable. */
2227 if (! dead_or_predicable (test_bb, then_bb, else_bb, new_lab, 1))
2230 /* Conversion went ok, including moving the insns and fixing up the
2231 jump. Adjust the CFG to match. */
2233 SET_UPDATE_LIFE (test_bb);
2234 bitmap_operation (test_bb->global_live_at_end,
2235 else_bb->global_live_at_start,
2236 then_bb->global_live_at_end, BITMAP_IOR);
2238 make_edge (NULL, test_bb, then_succ->dest, 0);
2239 flow_delete_block (then_bb);
2240 tidy_fallthru_edge (else_edge, test_bb, else_bb);
2242 num_removed_blocks++;
2243 num_updated_if_blocks++;
2248 /* Test for case 2 above. */
2251 find_if_case_2 (test_bb, then_edge, else_edge)
2252 basic_block test_bb;
2253 edge then_edge, else_edge;
2255 basic_block then_bb = then_edge->dest;
2256 basic_block else_bb = else_edge->dest;
2257 edge else_succ = else_bb->succ;
2260 /* ELSE has one successor. */
2261 if (!else_succ || else_succ->succ_next != NULL)
2264 /* ELSE outgoing edge is not complex. */
2265 if (else_succ->flags & EDGE_COMPLEX)
2268 /* ELSE has one predecessor. */
2269 if (else_bb->pred->pred_next != NULL)
2272 /* THEN is not EXIT. */
2273 if (then_bb->index < 0)
2276 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2277 note = find_reg_note (test_bb->end, REG_BR_PROB, NULL_RTX);
2278 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
2280 else if (else_succ->dest->index < 0
2281 || TEST_BIT (post_dominators[ORIG_INDEX (then_bb)],
2282 ORIG_INDEX (else_succ->dest)))
2287 num_possible_if_blocks++;
2289 fprintf (rtl_dump_file,
2290 "\nIF-CASE-2 found, start %d, else %d\n",
2291 test_bb->index, else_bb->index);
2293 /* ELSE is small. */
2294 if (count_bb_insns (then_bb) > BRANCH_COST)
2297 /* Find the label for ELSE's destination. */
2298 if (else_succ->dest == EXIT_BLOCK_PTR)
2302 if (else_succ->flags & EDGE_FALLTHRU)
2304 new_lab = else_succ->dest->head;
2305 if (GET_CODE (new_lab) != CODE_LABEL)
2310 new_lab = JUMP_LABEL (else_bb->end);
2316 /* Registers set are dead, or are predicable. */
2317 if (! dead_or_predicable (test_bb, else_bb, then_bb, new_lab, 0))
2320 /* Conversion went ok, including moving the insns and fixing up the
2321 jump. Adjust the CFG to match. */
2323 SET_UPDATE_LIFE (test_bb);
2324 bitmap_operation (test_bb->global_live_at_end,
2325 then_bb->global_live_at_start,
2326 else_bb->global_live_at_end, BITMAP_IOR);
2328 remove_edge (else_edge);
2329 make_edge (NULL, test_bb, else_succ->dest, 0);
2330 flow_delete_block (else_bb);
2332 num_removed_blocks++;
2333 num_updated_if_blocks++;
2335 /* ??? We may now fallthru from one of THEN's successors into a join
2336 block. Rerun cleanup_cfg? Examine things manually? Wait? */
2341 /* A subroutine of dead_or_predicable called through for_each_rtx.
2342 Return 1 if a memory is found. */
2345 find_memory (px, data)
2347 void *data ATTRIBUTE_UNUSED;
2349 return GET_CODE (*px) == MEM;
2352 /* Used by the code above to perform the actual rtl transformations.
2353 Return TRUE if successful.
2355 TEST_BB is the block containing the conditional branch. MERGE_BB
2356 is the block containing the code to manipulate. NEW_DEST is the
2357 label TEST_BB should be branching to after the conversion.
2358 REVERSEP is true if the sense of the branch should be reversed. */
2361 dead_or_predicable (test_bb, merge_bb, other_bb, new_dest, reversep)
2362 basic_block test_bb, merge_bb, other_bb;
2366 rtx head, end, jump, earliest, old_dest;
2368 jump = test_bb->end;
2370 /* Find the extent of the real code in the merge block. */
2371 head = merge_bb->head;
2372 end = merge_bb->end;
2374 if (GET_CODE (head) == CODE_LABEL)
2375 head = NEXT_INSN (head);
2376 if (GET_CODE (head) == NOTE)
2380 head = end = NULL_RTX;
2383 head = NEXT_INSN (head);
2386 if (GET_CODE (end) == JUMP_INSN)
2390 head = end = NULL_RTX;
2393 end = PREV_INSN (end);
2396 /* Disable handling dead code by conditional execution if the machine needs
2397 to do anything funny with the tests, etc. */
2398 #ifndef IFCVT_MODIFY_TESTS
2399 if (HAVE_conditional_execution)
2401 /* In the conditional execution case, we have things easy. We know
2402 the condition is reversable. We don't have to check life info,
2403 becase we're going to conditionally execute the code anyway.
2404 All that's left is making sure the insns involved can actually
2409 cond = cond_exec_get_condition (jump);
2413 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
2415 prob_val = XEXP (prob_val, 0);
2419 enum rtx_code rev = reversed_comparison_code (cond, jump);
2422 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
2425 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
2428 if (! cond_exec_process_insns (head, end, cond, prob_val, 0))
2436 /* In the non-conditional execution case, we have to verify that there
2437 are no trapping operations, no calls, no references to memory, and
2438 that any registers modified are dead at the branch site. */
2440 rtx insn, cond, prev;
2441 regset_head merge_set_head, tmp_head, test_live_head, test_set_head;
2442 regset merge_set, tmp, test_live, test_set;
2443 struct propagate_block_info *pbi;
2446 /* Check for no calls or trapping operations. */
2447 for (insn = head; ; insn = NEXT_INSN (insn))
2449 if (GET_CODE (insn) == CALL_INSN)
2453 if (may_trap_p (PATTERN (insn)))
2456 /* ??? Even non-trapping memories such as stack frame
2457 references must be avoided. For stores, we collect
2458 no lifetime info; for reads, we'd have to assert
2459 true_dependance false against every store in the
2461 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
2468 if (! any_condjump_p (jump))
2471 /* Find the extent of the conditional. */
2472 cond = noce_get_condition (jump, &earliest);
2477 MERGE_SET = set of registers set in MERGE_BB
2478 TEST_LIVE = set of registers live at EARLIEST
2479 TEST_SET = set of registers set between EARLIEST and the
2480 end of the block. */
2482 tmp = INITIALIZE_REG_SET (tmp_head);
2483 merge_set = INITIALIZE_REG_SET (merge_set_head);
2484 test_live = INITIALIZE_REG_SET (test_live_head);
2485 test_set = INITIALIZE_REG_SET (test_set_head);
2487 /* ??? bb->local_set is only valid during calculate_global_regs_live,
2488 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
2489 since we've already asserted that MERGE_BB is small. */
2490 propagate_block (merge_bb, tmp, merge_set, merge_set, 0);
2492 /* For small register class machines, don't lengthen lifetimes of
2493 hard registers before reload. */
2494 if (SMALL_REGISTER_CLASSES && ! reload_completed)
2496 EXECUTE_IF_SET_IN_BITMAP
2499 if (i < FIRST_PSEUDO_REGISTER
2501 && ! global_regs[i])
2506 /* For TEST, we're interested in a range of insns, not a whole block.
2507 Moreover, we're interested in the insns live from OTHER_BB. */
2509 COPY_REG_SET (test_live, other_bb->global_live_at_start);
2510 pbi = init_propagate_block_info (test_bb, test_live, test_set, test_set,
2513 for (insn = jump; ; insn = prev)
2515 prev = propagate_one_insn (pbi, insn);
2516 if (insn == earliest)
2520 free_propagate_block_info (pbi);
2522 /* We can perform the transformation if
2523 MERGE_SET & (TEST_SET | TEST_LIVE)
2525 TEST_SET & merge_bb->global_live_at_start
2528 bitmap_operation (tmp, test_set, test_live, BITMAP_IOR);
2529 bitmap_operation (tmp, tmp, merge_set, BITMAP_AND);
2530 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
2532 bitmap_operation (tmp, test_set, merge_bb->global_live_at_start,
2534 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
2537 FREE_REG_SET (merge_set);
2538 FREE_REG_SET (test_live);
2539 FREE_REG_SET (test_set);
2546 /* We don't want to use normal invert_jump or redirect_jump because
2547 we don't want to delete_insn called. Also, we want to do our own
2548 change group management. */
2550 old_dest = JUMP_LABEL (jump);
2552 ? ! invert_jump_1 (jump, new_dest)
2553 : ! redirect_jump_1 (jump, new_dest))
2556 if (! apply_change_group ())
2560 LABEL_NUSES (old_dest) -= 1;
2562 LABEL_NUSES (new_dest) += 1;
2563 JUMP_LABEL (jump) = new_dest;
2566 invert_br_probabilities (jump);
2568 /* Move the insns out of MERGE_BB to before the branch. */
2571 if (end == merge_bb->end)
2572 merge_bb->end = PREV_INSN (head);
2574 head = squeeze_notes (head, end);
2575 if (GET_CODE (end) == NOTE
2576 && (NOTE_LINE_NUMBER (end) == NOTE_INSN_BLOCK_END
2577 || NOTE_LINE_NUMBER (end) == NOTE_INSN_BLOCK_BEG
2578 || NOTE_LINE_NUMBER (end) == NOTE_INSN_LOOP_BEG
2579 || NOTE_LINE_NUMBER (end) == NOTE_INSN_LOOP_END
2580 || NOTE_LINE_NUMBER (end) == NOTE_INSN_LOOP_CONT
2581 || NOTE_LINE_NUMBER (end) == NOTE_INSN_LOOP_VTOP))
2585 end = PREV_INSN (end);
2588 reorder_insns (head, end, PREV_INSN (earliest));
2597 /* Main entry point for all if-conversion. */
2600 if_convert (x_life_data_ok)
2605 num_possible_if_blocks = 0;
2606 num_updated_if_blocks = 0;
2607 num_removed_blocks = 0;
2608 life_data_ok = (x_life_data_ok != 0);
2610 /* Free up basic_block_for_insn so that we don't have to keep it
2611 up to date, either here or in merge_blocks_nomove. */
2612 free_basic_block_vars (1);
2614 /* Compute postdominators if we think we'll use them. */
2615 post_dominators = NULL;
2616 if (HAVE_conditional_execution || life_data_ok)
2618 post_dominators = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
2619 calculate_dominance_info (NULL, post_dominators, CDI_POST_DOMINATORS);
2622 /* Record initial block numbers. */
2623 for (block_num = 0; block_num < n_basic_blocks; block_num++)
2624 SET_ORIG_INDEX (BASIC_BLOCK (block_num), block_num);
2626 /* Go through each of the basic blocks looking for things to convert. */
2627 for (block_num = 0; block_num < n_basic_blocks; )
2629 basic_block bb = BASIC_BLOCK (block_num);
2630 if (find_if_header (bb))
2631 block_num = bb->index;
2636 if (post_dominators)
2637 sbitmap_vector_free (post_dominators);
2640 fflush (rtl_dump_file);
2642 /* Rebuild basic_block_for_insn for update_life_info and for gcse. */
2643 compute_bb_for_insn (get_max_uid ());
2645 /* Rebuild life info for basic blocks that require it. */
2646 if (num_removed_blocks && life_data_ok)
2648 sbitmap update_life_blocks = sbitmap_alloc (n_basic_blocks);
2649 sbitmap_zero (update_life_blocks);
2651 /* If we allocated new pseudos, we must resize the array for sched1. */
2652 if (max_regno < max_reg_num ())
2654 max_regno = max_reg_num ();
2655 allocate_reg_info (max_regno, FALSE, FALSE);
2658 for (block_num = 0; block_num < n_basic_blocks; block_num++)
2659 if (UPDATE_LIFE (BASIC_BLOCK (block_num)))
2660 SET_BIT (update_life_blocks, block_num);
2662 count_or_remove_death_notes (update_life_blocks, 1);
2663 /* ??? See about adding a mode that verifies that the initial
2664 set of blocks don't let registers come live. */
2665 update_life_info (update_life_blocks, UPDATE_LIFE_GLOBAL,
2666 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2667 | PROP_KILL_DEAD_CODE);
2669 sbitmap_free (update_life_blocks);
2672 /* Write the final stats. */
2673 if (rtl_dump_file && num_possible_if_blocks > 0)
2675 fprintf (rtl_dump_file,
2676 "\n%d possible IF blocks searched.\n",
2677 num_possible_if_blocks);
2678 fprintf (rtl_dump_file,
2679 "%d IF blocks converted.\n",
2680 num_updated_if_blocks);
2681 fprintf (rtl_dump_file,
2682 "%d basic blocks deleted.\n\n\n",
2683 num_removed_blocks);
2686 #ifdef ENABLE_CHECKING
2687 verify_flow_info ();