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"
37 #ifndef HAVE_conditional_execution
38 #define HAVE_conditional_execution 0
40 #ifndef HAVE_conditional_move
41 #define HAVE_conditional_move 0
50 #ifndef MAX_CONDITIONAL_EXECUTE
51 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
54 #define EDGE_COMPLEX (EDGE_ABNORMAL | EDGE_ABNORMAL_CALL | EDGE_EH)
56 #define NULL_EDGE ((struct edge_def *)NULL)
57 #define NULL_BLOCK ((struct basic_block_def *)NULL)
59 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
60 static int num_possible_if_blocks;
62 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
64 static int num_updated_if_blocks;
66 /* # of basic blocks that were removed. */
67 static int num_removed_blocks;
69 /* The post-dominator relation on the original block numbers. */
70 static sbitmap *post_dominators;
72 /* Forward references. */
73 static int count_bb_insns PARAMS ((basic_block));
74 static rtx first_active_insn PARAMS ((basic_block));
75 static int last_active_insn_p PARAMS ((basic_block, rtx));
76 static int seq_contains_jump PARAMS ((rtx));
78 static int cond_exec_process_insns PARAMS ((rtx, rtx, rtx, rtx, int));
79 static rtx cond_exec_get_condition PARAMS ((rtx));
80 static int cond_exec_process_if_block PARAMS ((basic_block, basic_block,
81 basic_block, basic_block));
83 static rtx noce_get_condition PARAMS ((rtx, rtx *));
84 static int noce_process_if_block PARAMS ((basic_block, basic_block,
85 basic_block, basic_block));
87 static int process_if_block PARAMS ((basic_block, basic_block,
88 basic_block, basic_block));
89 static void merge_if_block PARAMS ((basic_block, basic_block,
90 basic_block, basic_block));
92 static int find_if_header PARAMS ((basic_block));
93 static int find_if_block PARAMS ((basic_block, edge, edge));
94 static int find_if_case_1 PARAMS ((basic_block, edge, edge));
95 static int find_if_case_2 PARAMS ((basic_block, edge, edge));
96 static int find_memory PARAMS ((rtx *, void *));
97 static int dead_or_predicable PARAMS ((basic_block, basic_block,
98 basic_block, rtx, int));
100 /* Abuse the basic_block AUX field to store the original block index,
101 as well as a flag indicating that the block should be rescaned for
104 #define SET_ORIG_INDEX(BB,I) ((BB)->aux = (void *)((size_t)(I) << 1))
105 #define ORIG_INDEX(BB) ((size_t)(BB)->aux >> 1)
106 #define SET_UPDATE_LIFE(BB) ((BB)->aux = (void *)((size_t)(BB)->aux | 1))
107 #define UPDATE_LIFE(BB) ((size_t)(BB)->aux & 1)
110 /* Count the number of non-jump active insns in BB. */
121 if (GET_CODE (insn) == CALL_INSN || GET_CODE (insn) == INSN)
126 insn = NEXT_INSN (insn);
132 /* Return the first non-jump active insn in the basic block. */
135 first_active_insn (bb)
140 if (GET_CODE (insn) == CODE_LABEL)
144 insn = NEXT_INSN (insn);
147 while (GET_CODE (insn) == NOTE)
151 insn = NEXT_INSN (insn);
154 if (GET_CODE (insn) == JUMP_INSN)
160 /* Return true if INSN is the last active non-jump insn in BB. */
163 last_active_insn_p (bb, insn)
171 insn = NEXT_INSN (insn);
173 while (GET_CODE (insn) == NOTE);
175 return GET_CODE (insn) == JUMP_INSN;
178 /* It is possible, especially when having dealt with multi-word
179 arithmetic, for the expanders to have emitted jumps. Search
180 through the sequence and return TRUE if a jump exists so that
181 we can abort the conversion. */
184 seq_contains_jump (insn)
189 if (GET_CODE (insn) == JUMP_INSN)
191 insn = NEXT_INSN (insn);
196 /* Go through a bunch of insns, converting them to conditional
197 execution format if possible. Return TRUE if all of the non-note
198 insns were processed. */
201 cond_exec_process_insns (start, end, test, prob_val, mod_ok)
202 rtx start; /* first insn to look at */
203 rtx end; /* last insn to look at */
204 rtx test; /* conditional execution test */
205 rtx prob_val; /* probability of branch taken. */
206 int mod_ok; /* true if modifications ok last insn. */
208 int must_be_last = FALSE;
211 for (insn = start; ; insn = NEXT_INSN (insn))
213 if (GET_CODE (insn) == NOTE)
216 if (GET_CODE (insn) != INSN && GET_CODE (insn) != CALL_INSN)
219 /* Remove USE and CLOBBER insns that get in the way. */
221 && (GET_CODE (PATTERN (insn)) == USE
222 || GET_CODE (PATTERN (insn)) == CLOBBER))
224 /* ??? Ug. Actually unlinking the thing is problematic,
225 given what we'd have to coordinate with our callers. */
226 PUT_CODE (insn, NOTE);
227 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
228 NOTE_SOURCE_FILE (insn) = 0;
232 /* Last insn wasn't last? */
236 if (modified_in_p (test, insn))
243 /* Now build the conditional form of the instruction. */
244 validate_change (insn, &PATTERN (insn),
245 gen_rtx_COND_EXEC (VOIDmode, copy_rtx (test),
248 if (GET_CODE (insn) == CALL_INSN && prob_val)
249 validate_change (insn, ®_NOTES (insn),
250 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
251 REG_NOTES (insn)), 1);
261 /* Return the condition for a jump. Do not do any special processing. */
264 cond_exec_get_condition (jump)
269 if (any_condjump_p (jump))
270 test_if = SET_SRC (pc_set (jump));
273 cond = XEXP (test_if, 0);
275 /* If this branches to JUMP_LABEL when the condition is false,
276 reverse the condition. */
277 if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF
278 && XEXP (XEXP (test_if, 2), 0) == JUMP_LABEL (jump))
279 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
280 GET_MODE (cond), XEXP (cond, 0),
286 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
287 to conditional execution. Return TRUE if we were successful at
288 converting the the block. */
291 cond_exec_process_if_block (test_bb, then_bb, else_bb, join_bb)
292 basic_block test_bb; /* Basic block test is in */
293 basic_block then_bb; /* Basic block for THEN block */
294 basic_block else_bb; /* Basic block for ELSE block */
295 basic_block join_bb; /* Basic block the join label is in */
297 rtx test_expr; /* expression in IF_THEN_ELSE that is tested */
298 rtx then_start; /* first insn in THEN block */
299 rtx then_end; /* last insn + 1 in THEN block */
300 rtx else_start; /* first insn in ELSE block or NULL */
301 rtx else_end; /* last insn + 1 in ELSE block */
302 int max; /* max # of insns to convert. */
303 int then_mod_ok; /* whether conditional mods are ok in THEN */
304 rtx true_expr; /* test for else block insns */
305 rtx false_expr; /* test for then block insns */
306 rtx true_prob_val; /* probability of else block */
307 rtx false_prob_val; /* probability of then block */
310 /* Find the conditional jump to the ELSE or JOIN part, and isolate
312 test_expr = cond_exec_get_condition (test_bb->end);
316 /* Collect the bounds of where we're to search. */
318 then_start = then_bb->head;
319 then_end = then_bb->end;
321 /* Skip a label heading THEN block. */
322 if (GET_CODE (then_start) == CODE_LABEL)
323 then_start = NEXT_INSN (then_start);
325 /* Skip a (use (const_int 0)) or branch as the final insn. */
326 if (GET_CODE (then_end) == INSN
327 && GET_CODE (PATTERN (then_end)) == USE
328 && GET_CODE (XEXP (PATTERN (then_end), 0)) == CONST_INT)
329 then_end = PREV_INSN (then_end);
330 else if (GET_CODE (then_end) == JUMP_INSN)
331 then_end = PREV_INSN (then_end);
335 /* Skip the ELSE block's label. */
336 else_start = NEXT_INSN (else_bb->head);
337 else_end = else_bb->end;
339 /* Skip a (use (const_int 0)) or branch as the final insn. */
340 if (GET_CODE (else_end) == INSN
341 && GET_CODE (PATTERN (else_end)) == USE
342 && GET_CODE (XEXP (PATTERN (else_end), 0)) == CONST_INT)
343 else_end = PREV_INSN (else_end);
344 else if (GET_CODE (else_end) == JUMP_INSN)
345 else_end = PREV_INSN (else_end);
348 /* How many instructions should we convert in total? */
352 max = 2 * MAX_CONDITIONAL_EXECUTE;
353 n_insns = count_bb_insns (else_bb);
356 max = MAX_CONDITIONAL_EXECUTE;
357 n_insns += count_bb_insns (then_bb);
361 /* Map test_expr/test_jump into the appropriate MD tests to use on
362 the conditionally executed code. */
364 true_expr = test_expr;
365 false_expr = gen_rtx_fmt_ee (reverse_condition (GET_CODE (true_expr)),
366 GET_MODE (true_expr), XEXP (true_expr, 0),
367 XEXP (true_expr, 1));
369 true_prob_val = find_reg_note (test_bb->end, REG_BR_PROB, NULL_RTX);
372 true_prob_val = XEXP (true_prob_val, 0);
373 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
376 false_prob_val = NULL_RTX;
378 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
379 on then THEN block. */
380 then_mod_ok = (else_bb == NULL_BLOCK);
382 /* Go through the THEN and ELSE blocks converting the insns if possible
383 to conditional execution. */
386 && ! cond_exec_process_insns (then_start, then_end,
387 false_expr, false_prob_val, then_mod_ok))
391 && ! cond_exec_process_insns (else_start, else_end,
392 true_expr, true_prob_val, TRUE))
395 if (! apply_change_group ())
398 /* Conversion succeeded. */
400 fprintf (rtl_dump_file, "%d insn%s converted to conditional execution.\n",
401 n_insns, (n_insns == 1) ? " was" : "s were");
403 /* Merge the blocks! */
404 merge_if_block (test_bb, then_bb, else_bb, join_bb);
412 /* Used by noce_process_if_block to communicate with its subroutines.
414 The subroutines know that A and B may be evaluated freely. They
415 know that X is a register. They should insert new instructions
416 before cond_earliest. */
422 rtx jump, cond, cond_earliest;
425 static rtx noce_emit_store_flag PARAMS ((struct noce_if_info *,
427 static int noce_try_store_flag PARAMS ((struct noce_if_info *));
428 static int noce_try_store_flag_inc PARAMS ((struct noce_if_info *));
429 static int noce_try_store_flag_constants PARAMS ((struct noce_if_info *));
430 static int noce_try_store_flag_mask PARAMS ((struct noce_if_info *));
431 static rtx noce_emit_cmove PARAMS ((struct noce_if_info *,
432 rtx, enum rtx_code, rtx,
434 static int noce_try_cmove PARAMS ((struct noce_if_info *));
435 static int noce_try_cmove_arith PARAMS ((struct noce_if_info *));
437 /* Helper function for noce_try_store_flag*. */
440 noce_emit_store_flag (if_info, x, reversep, normalize)
441 struct noce_if_info *if_info;
443 int reversep, normalize;
445 rtx cond = if_info->cond;
449 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
450 || ! general_operand (XEXP (cond, 1), VOIDmode));
452 /* If earliest == jump, or when the condition is complex, try to
453 build the store_flag insn directly. */
456 cond = XEXP (SET_SRC (PATTERN (if_info->jump)), 0);
458 if ((if_info->cond_earliest == if_info->jump || cond_complex)
459 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
463 code = GET_CODE (cond);
465 code = reverse_condition (code);
467 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
469 tmp = gen_rtx_SET (VOIDmode, x, tmp);
472 tmp = emit_insn (tmp);
474 if (recog_memoized (tmp) >= 0)
480 if_info->cond_earliest = if_info->jump;
488 /* Don't even try if the comparison operands are weird. */
492 code = GET_CODE (cond);
494 code = reverse_condition (code);
496 return emit_store_flag (x, code, XEXP (cond, 0),
497 XEXP (cond, 1), VOIDmode,
498 (code == LTU || code == LEU
499 || code == GEU || code == GTU), normalize);
502 /* Convert "if (test) x = 1; else x = 0".
504 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
505 tried in noce_try_store_flag_constants after noce_try_cmove has had
506 a go at the conversion. */
509 noce_try_store_flag (if_info)
510 struct noce_if_info *if_info;
515 if (GET_CODE (if_info->b) == CONST_INT
516 && INTVAL (if_info->b) == STORE_FLAG_VALUE
517 && if_info->a == const0_rtx)
519 else if (if_info->b == const0_rtx
520 && GET_CODE (if_info->a) == CONST_INT
521 && INTVAL (if_info->a) == STORE_FLAG_VALUE
522 && can_reverse_comparison_p (if_info->cond, if_info->jump))
529 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
532 if (target != if_info->x)
533 emit_move_insn (if_info->x, target);
537 emit_insns_before (seq, if_info->cond_earliest);
548 /* Convert "if (test) x = a; else x = b", for A and B constant. */
551 noce_try_store_flag_constants (if_info)
552 struct noce_if_info *if_info;
556 HOST_WIDE_INT itrue, ifalse, diff, tmp;
557 int normalize, can_reverse;
560 && GET_CODE (if_info->a) == CONST_INT
561 && GET_CODE (if_info->b) == CONST_INT)
563 ifalse = INTVAL (if_info->a);
564 itrue = INTVAL (if_info->b);
565 diff = itrue - ifalse;
567 can_reverse = can_reverse_comparison_p (if_info->cond, if_info->jump);
570 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
572 else if (ifalse == 0 && exact_log2 (itrue) >= 0
573 && (STORE_FLAG_VALUE == 1
574 || BRANCH_COST >= 2))
576 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
577 && (STORE_FLAG_VALUE == 1 || BRANCH_COST >= 2))
578 normalize = 1, reversep = 1;
580 && (STORE_FLAG_VALUE == -1
581 || BRANCH_COST >= 2))
583 else if (ifalse == -1 && can_reverse
584 && (STORE_FLAG_VALUE == -1 || BRANCH_COST >= 2))
585 normalize = -1, reversep = 1;
586 else if ((BRANCH_COST >= 2 && STORE_FLAG_VALUE == -1)
594 tmp = itrue; itrue = ifalse; ifalse = tmp;
599 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
606 /* if (test) x = 3; else x = 4;
607 => x = 3 + (test == 0); */
608 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
610 target = expand_binop (GET_MODE (if_info->x),
611 (diff == STORE_FLAG_VALUE
612 ? add_optab : sub_optab),
613 GEN_INT (ifalse), target, if_info->x, 0,
617 /* if (test) x = 8; else x = 0;
618 => x = (test != 0) << 3; */
619 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
621 target = expand_binop (GET_MODE (if_info->x), ashl_optab,
622 target, GEN_INT (tmp), if_info->x, 0,
626 /* if (test) x = -1; else x = b;
627 => x = -(test != 0) | b; */
628 else if (itrue == -1)
630 target = expand_binop (GET_MODE (if_info->x), ior_optab,
631 target, GEN_INT (ifalse), if_info->x, 0,
635 /* if (test) x = a; else x = b;
636 => x = (-(test != 0) & (b - a)) + a; */
639 target = expand_binop (GET_MODE (if_info->x), and_optab,
640 target, GEN_INT (diff), if_info->x, 0,
643 target = expand_binop (GET_MODE (if_info->x), add_optab,
644 target, GEN_INT (ifalse), if_info->x, 0,
654 if (target != if_info->x)
655 emit_move_insn (if_info->x, target);
660 if (seq_contains_jump (seq))
663 emit_insns_before (seq, if_info->cond_earliest);
671 /* Convert "if (test) foo++" into "foo += (test != 0)", and
672 similarly for "foo--". */
675 noce_try_store_flag_inc (if_info)
676 struct noce_if_info *if_info;
679 int subtract, normalize;
685 /* Should be no `else' case to worry about. */
686 && if_info->b == if_info->x
687 && GET_CODE (if_info->a) == PLUS
688 && (XEXP (if_info->a, 1) == const1_rtx
689 || XEXP (if_info->a, 1) == constm1_rtx)
690 && rtx_equal_p (XEXP (if_info->a, 0), if_info->x)
691 && can_reverse_comparison_p (if_info->cond, if_info->jump))
693 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
694 subtract = 0, normalize = 0;
695 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
696 subtract = 1, normalize = 0;
698 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
702 target = noce_emit_store_flag (if_info,
703 gen_reg_rtx (GET_MODE (if_info->x)),
707 target = expand_binop (GET_MODE (if_info->x),
708 subtract ? sub_optab : add_optab,
709 if_info->x, target, if_info->x, 0, OPTAB_WIDEN);
712 if (target != if_info->x)
713 emit_move_insn (if_info->x, target);
718 if (seq_contains_jump (seq))
721 emit_insns_before (seq, if_info->cond_earliest);
732 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
735 noce_try_store_flag_mask (if_info)
736 struct noce_if_info *if_info;
744 || STORE_FLAG_VALUE == -1)
745 && ((if_info->a == const0_rtx
746 && rtx_equal_p (if_info->b, if_info->x))
747 || ((reversep = can_reverse_comparison_p (if_info->cond,
749 && if_info->b == const0_rtx
750 && rtx_equal_p (if_info->a, if_info->x))))
753 target = noce_emit_store_flag (if_info,
754 gen_reg_rtx (GET_MODE (if_info->x)),
757 target = expand_binop (GET_MODE (if_info->x), and_optab,
758 if_info->x, target, if_info->x, 0,
763 if (target != if_info->x)
764 emit_move_insn (if_info->x, target);
769 if (seq_contains_jump (seq))
772 emit_insns_before (seq, if_info->cond_earliest);
783 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
786 noce_emit_cmove (if_info, x, code, cmp_a, cmp_b, vfalse, vtrue)
787 struct noce_if_info *if_info;
788 rtx x, cmp_a, cmp_b, vfalse, vtrue;
791 /* If earliest == jump, try to build the cmove insn directly.
792 This is helpful when combine has created some complex condition
793 (like for alpha's cmovlbs) that we can't hope to regenerate
794 through the normal interface. */
796 if (if_info->cond_earliest == if_info->jump)
800 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
801 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
802 tmp = gen_rtx_SET (VOIDmode, x, tmp);
805 tmp = emit_insn (tmp);
807 if (recog_memoized (tmp) >= 0)
819 /* Don't even try if the comparison operands are weird. */
820 if (! general_operand (cmp_a, GET_MODE (cmp_a))
821 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
824 #if HAVE_conditional_move
825 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
826 vtrue, vfalse, GET_MODE (x),
827 (code == LTU || code == GEU
828 || code == LEU || code == GTU));
830 /* We'll never get here, as noce_process_if_block doesn't call the
831 functions involved. Ifdef code, however, should be discouraged
832 because it leads to typos in the code not selected. However,
833 emit_conditional_move won't exist either. */
838 /* Try only simple constants and registers here. More complex cases
839 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
840 has had a go at it. */
843 noce_try_cmove (if_info)
844 struct noce_if_info *if_info;
849 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
850 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
854 code = GET_CODE (if_info->cond);
855 target = noce_emit_cmove (if_info, if_info->x, code,
856 XEXP (if_info->cond, 0),
857 XEXP (if_info->cond, 1),
858 if_info->a, if_info->b);
862 if (target != if_info->x)
863 emit_move_insn (if_info->x, target);
867 emit_insns_before (seq, if_info->cond_earliest);
880 /* Try more complex cases involving conditional_move. */
883 noce_try_cmove_arith (if_info)
884 struct noce_if_info *if_info;
894 /* A conditional move from two memory sources is equivalent to a
895 conditional on their addresses followed by a load. Don't do this
896 early because it'll screw alias analysis. Note that we've
897 already checked for no side effects. */
898 if (! no_new_pseudos && cse_not_expected
899 && GET_CODE (a) == MEM && GET_CODE (b) == MEM
904 x = gen_reg_rtx (Pmode);
908 /* ??? We could handle this if we knew that a load from A or B could
909 not fault. This is also true if we've already loaded
910 from the address along the path from ENTRY. */
911 else if (may_trap_p (a) || may_trap_p (b))
914 /* if (test) x = a + b; else x = c - d;
921 code = GET_CODE (if_info->cond);
922 insn_a = if_info->insn_a;
923 insn_b = if_info->insn_b;
925 /* Possibly rearrange operands to make things come out more natural. */
926 if (can_reverse_comparison_p (if_info->cond, if_info->jump))
929 if (rtx_equal_p (b, x))
931 else if (general_operand (b, GET_MODE (b)))
936 code = reverse_condition (code);
937 tmp = a, a = b, b = tmp;
938 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
944 /* If either operand is complex, load it into a register first.
945 The best way to do this is to copy the original insn. In this
946 way we preserve any clobbers etc that the insn may have had.
947 This is of course not possible in the IS_MEM case. */
948 if (! general_operand (a, GET_MODE (a)))
953 goto end_seq_and_fail;
957 tmp = gen_reg_rtx (GET_MODE (a));
958 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
961 goto end_seq_and_fail;
964 a = gen_reg_rtx (GET_MODE (a));
965 tmp = copy_rtx (insn_a);
966 set = single_set (tmp);
968 tmp = emit_insn (PATTERN (tmp));
970 if (recog_memoized (tmp) < 0)
971 goto end_seq_and_fail;
973 if (! general_operand (b, GET_MODE (b)))
978 goto end_seq_and_fail;
982 tmp = gen_reg_rtx (GET_MODE (b));
983 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, b));
986 goto end_seq_and_fail;
989 b = gen_reg_rtx (GET_MODE (b));
990 tmp = copy_rtx (insn_b);
991 set = single_set (tmp);
993 tmp = emit_insn (PATTERN (tmp));
995 if (recog_memoized (tmp) < 0)
996 goto end_seq_and_fail;
999 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1000 XEXP (if_info->cond, 1), a, b);
1003 goto end_seq_and_fail;
1005 /* If we're handling a memory for above, emit the load now. */
1008 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1010 /* Copy over flags as appropriate. */
1011 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1012 MEM_VOLATILE_P (tmp) = 1;
1013 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1014 MEM_IN_STRUCT_P (tmp) = 1;
1015 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1016 MEM_SCALAR_P (tmp) = 1;
1017 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1018 MEM_ALIAS_SET (tmp) = MEM_ALIAS_SET (if_info->a);
1020 emit_move_insn (if_info->x, tmp);
1022 else if (target != x)
1023 emit_move_insn (x, target);
1027 emit_insns_before (tmp, if_info->cond_earliest);
1035 /* Look for the condition for the jump first. We'd prefer to avoid
1036 get_condition if we can -- it tries to look back for the contents
1037 of an original compare. On targets that use normal integers for
1038 comparisons, e.g. alpha, this is wasteful. */
1041 noce_get_condition (jump, earliest)
1048 /* If the condition variable is a register and is MODE_INT, accept it.
1049 Otherwise, fall back on get_condition. */
1051 if (! any_condjump_p (jump))
1054 set = pc_set (jump);
1056 cond = XEXP (SET_SRC (set), 0);
1057 if (GET_CODE (XEXP (cond, 0)) == REG
1058 && GET_MODE_CLASS (GET_MODE (XEXP (cond, 0))) == MODE_INT)
1062 /* If this branches to JUMP_LABEL when the condition is false,
1063 reverse the condition. */
1064 if (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1065 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump))
1066 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
1067 GET_MODE (cond), XEXP (cond, 0),
1071 cond = get_condition (jump, earliest);
1076 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1077 without using conditional execution. Return TRUE if we were
1078 successful at converting the the block. */
1081 noce_process_if_block (test_bb, then_bb, else_bb, join_bb)
1082 basic_block test_bb; /* Basic block test is in */
1083 basic_block then_bb; /* Basic block for THEN block */
1084 basic_block else_bb; /* Basic block for ELSE block */
1085 basic_block join_bb; /* Basic block the join label is in */
1087 /* We're looking for patterns of the form
1089 (1) if (...) x = a; else x = b;
1090 (2) x = b; if (...) x = a;
1091 (3) if (...) x = a; // as if with an initial x = x.
1093 The later patterns require jumps to be more expensive.
1095 ??? For future expansion, look for multiple X in such patterns. */
1097 struct noce_if_info if_info;
1100 rtx orig_x, x, a, b;
1101 rtx jump, cond, insn;
1103 /* If this is not a standard conditional jump, we can't parse it. */
1104 jump = test_bb->end;
1105 cond = noce_get_condition (jump, &if_info.cond_earliest);
1109 /* We must be comparing objects whose modes imply the size. */
1110 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
1113 /* Look for one of the potential sets. */
1114 insn_a = first_active_insn (then_bb);
1116 || ! last_active_insn_p (then_bb, insn_a)
1117 || (set_a = single_set (insn_a)) == NULL_RTX)
1120 x = SET_DEST (set_a);
1121 a = SET_SRC (set_a);
1123 /* Look for the other potential set. Make sure we've got equivalent
1125 /* ??? This is overconservative. Storing to two different mems is
1126 as easy as conditionally computing the address. Storing to a
1127 single mem merely requires a scratch memory to use as one of the
1128 destination addresses; often the memory immediately below the
1129 stack pointer is available for this. */
1133 insn_b = first_active_insn (else_bb);
1135 || ! last_active_insn_p (else_bb, insn_b)
1136 || (set_b = single_set (insn_b)) == NULL_RTX
1137 || ! rtx_equal_p (x, SET_DEST (set_b)))
1142 insn_b = prev_nonnote_insn (if_info.cond_earliest);
1144 || GET_CODE (insn_b) != INSN
1145 || (set_b = single_set (insn_b)) == NULL_RTX
1146 || ! rtx_equal_p (x, SET_DEST (set_b))
1147 || reg_mentioned_p (x, cond)
1148 || reg_mentioned_p (x, a)
1149 || reg_mentioned_p (x, SET_SRC (set_b)))
1150 insn_b = set_b = NULL_RTX;
1152 b = (set_b ? SET_SRC (set_b) : x);
1154 /* X may not be mentioned in the range (cond_earliest, jump]. */
1155 for (insn = jump; insn != if_info.cond_earliest; insn = PREV_INSN (insn))
1156 if (INSN_P (insn) && reg_mentioned_p (x, insn))
1159 /* A and B may not be modified in the range [cond_earliest, jump). */
1160 for (insn = if_info.cond_earliest; insn != jump; insn = NEXT_INSN (insn))
1162 && (modified_in_p (a, insn) || modified_in_p (b, insn)))
1165 /* Only operate on register destinations, and even then avoid extending
1166 the lifetime of hard registers on small register class machines. */
1168 if (GET_CODE (x) != REG
1169 || (SMALL_REGISTER_CLASSES
1170 && REGNO (x) < FIRST_PSEUDO_REGISTER))
1174 x = gen_reg_rtx (GET_MODE (x));
1177 /* Don't operate on sources that may trap or are volatile. */
1178 if (side_effects_p (a) || side_effects_p (b)
1179 || (GET_CODE (a) != MEM && may_trap_p (a))
1180 || (GET_CODE (b) != MEM && may_trap_p (b)))
1183 /* Set up the info block for our subroutines. */
1184 if_info.cond = cond;
1185 if_info.jump = jump;
1186 if_info.insn_a = insn_a;
1187 if_info.insn_b = insn_b;
1192 /* Try optimizations in some approximation of a useful order. */
1193 /* ??? Should first look to see if X is live incoming at all. If it
1194 isn't, we don't need anything but an unconditional set. */
1196 /* Look and see if A and B are really the same. Avoid creating silly
1197 cmove constructs that no one will fix up later. */
1198 if (rtx_equal_p (a, b))
1200 /* If we have an INSN_B, we don't have to create any new rtl. Just
1201 move the instruction that we already have. If we don't have an
1202 INSN_B, that means that A == X, and we've got a noop move. In
1203 that case don't do anything and let the code below delete INSN_A. */
1204 if (insn_b && else_bb)
1206 if (else_bb && insn_b == else_bb->end)
1207 else_bb->end = PREV_INSN (insn_b);
1208 reorder_insns (insn_b, insn_b, PREV_INSN (if_info.cond_earliest));
1215 if (noce_try_store_flag (&if_info))
1217 if (HAVE_conditional_move
1218 && noce_try_cmove (&if_info))
1220 if (! HAVE_conditional_execution)
1222 if (noce_try_store_flag_constants (&if_info))
1224 if (noce_try_store_flag_inc (&if_info))
1226 if (noce_try_store_flag_mask (&if_info))
1228 if (HAVE_conditional_move
1229 && noce_try_cmove_arith (&if_info))
1236 /* The original sets may now be killed. */
1237 if (insn_a == then_bb->end)
1238 then_bb->end = PREV_INSN (insn_a);
1239 flow_delete_insn (insn_a);
1241 /* Several special cases here: First, we may have reused insn_b above,
1242 in which case insn_b is now NULL. Second, we want to delete insn_b
1243 if it came from the ELSE block, because follows the now correct
1244 write that appears in the TEST block. However, if we got insn_b from
1245 the TEST block, it may in fact be loading data needed for the comparison.
1246 We'll let life_analysis remove the insn if it's really dead. */
1247 if (insn_b && else_bb)
1249 if (insn_b == else_bb->end)
1250 else_bb->end = PREV_INSN (insn_b);
1251 flow_delete_insn (insn_b);
1254 /* The new insns will have been inserted before cond_earliest. We should
1255 be able to remove the jump with impunity, but the condition itself may
1256 have been modified by gcse to be shared across basic blocks. */
1257 test_bb->end = PREV_INSN (jump);
1258 flow_delete_insn (jump);
1260 /* If we used a temporary, fix it up now. */
1264 emit_move_insn (orig_x, x);
1265 insn_b = gen_sequence ();
1268 test_bb->end = emit_insn_after (insn_b, test_bb->end);
1271 /* Merge the blocks! */
1272 merge_if_block (test_bb, then_bb, else_bb, join_bb);
1277 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
1278 straight line code. Return true if successful. */
1281 process_if_block (test_bb, then_bb, else_bb, join_bb)
1282 basic_block test_bb; /* Basic block test is in */
1283 basic_block then_bb; /* Basic block for THEN block */
1284 basic_block else_bb; /* Basic block for ELSE block */
1285 basic_block join_bb; /* Basic block the join label is in */
1287 if (! reload_completed
1288 && noce_process_if_block (test_bb, then_bb, else_bb, join_bb))
1291 if (HAVE_conditional_execution
1293 && cond_exec_process_if_block (test_bb, then_bb, else_bb, join_bb))
1299 /* Merge the blocks and mark for local life update. */
1302 merge_if_block (test_bb, then_bb, else_bb, join_bb)
1303 basic_block test_bb; /* Basic block test is in */
1304 basic_block then_bb; /* Basic block for THEN block */
1305 basic_block else_bb; /* Basic block for ELSE block */
1306 basic_block join_bb; /* Basic block the join label is in */
1308 basic_block combo_bb;
1310 /* All block merging is done into the lower block numbers. */
1314 /* First merge TEST block into THEN block. This is a no-brainer since
1315 the THEN block did not have a code label to begin with. */
1317 if (combo_bb->global_live_at_end)
1318 COPY_REG_SET (combo_bb->global_live_at_end, then_bb->global_live_at_end);
1319 merge_blocks_nomove (combo_bb, then_bb);
1320 num_removed_blocks++;
1322 /* The ELSE block, if it existed, had a label. That label count
1323 will almost always be zero, but odd things can happen when labels
1324 get their addresses taken. */
1327 merge_blocks_nomove (combo_bb, else_bb);
1328 num_removed_blocks++;
1331 /* If there was no join block reported, that means it was not adjacent
1332 to the others, and so we cannot merge them. */
1336 /* The outgoing edge for the current COMBO block should already
1337 be correct. Verify this. */
1338 if (combo_bb->succ == NULL_EDGE)
1341 /* There should sill be a branch at the end of the THEN or ELSE
1342 blocks taking us to our final destination. */
1343 if (! simplejump_p (combo_bb->end)
1344 && ! returnjump_p (combo_bb->end))
1348 /* The JOIN block may have had quite a number of other predecessors too.
1349 Since we've already merged the TEST, THEN and ELSE blocks, we should
1350 have only one remaining edge from our if-then-else diamond. If there
1351 is more than one remaining edge, it must come from elsewhere. */
1352 else if (join_bb->pred->pred_next == NULL)
1354 /* We can merge the JOIN. */
1355 if (combo_bb->global_live_at_end)
1356 COPY_REG_SET (combo_bb->global_live_at_end,
1357 join_bb->global_live_at_end);
1358 merge_blocks_nomove (combo_bb, join_bb);
1359 num_removed_blocks++;
1363 /* We cannot merge the JOIN. */
1365 /* The outgoing edge for the current COMBO block should already
1366 be correct. Verify this. */
1367 if (combo_bb->succ->succ_next != NULL_EDGE
1368 || combo_bb->succ->dest != join_bb)
1371 /* Remove the jump and cruft from the end of the COMBO block. */
1372 tidy_fallthru_edge (combo_bb->succ, combo_bb, join_bb);
1375 /* Make sure we update life info properly. */
1376 SET_UPDATE_LIFE (combo_bb);
1378 num_updated_if_blocks++;
1381 /* Find a block ending in a simple IF condition. Return TRUE if
1382 we were able to transform it in some way. */
1385 find_if_header (test_bb)
1386 basic_block test_bb;
1391 /* The kind of block we're looking for has exactly two successors. */
1392 if ((then_edge = test_bb->succ) == NULL_EDGE
1393 || (else_edge = then_edge->succ_next) == NULL_EDGE
1394 || else_edge->succ_next != NULL_EDGE)
1397 /* Neither edge should be abnormal. */
1398 if ((then_edge->flags & EDGE_COMPLEX)
1399 || (else_edge->flags & EDGE_COMPLEX))
1402 /* The THEN edge is canonically the one that falls through. */
1403 if (then_edge->flags & EDGE_FALLTHRU)
1405 else if (else_edge->flags & EDGE_FALLTHRU)
1408 else_edge = then_edge;
1412 /* Otherwise this must be a multiway branch of some sort. */
1415 if (find_if_block (test_bb, then_edge, else_edge))
1418 && (! HAVE_conditional_execution || reload_completed))
1420 if (find_if_case_1 (test_bb, then_edge, else_edge))
1422 if (find_if_case_2 (test_bb, then_edge, else_edge))
1430 fprintf (rtl_dump_file, "Conversion succeeded.\n");
1434 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
1435 block. If so, we'll try to convert the insns to not require the branch.
1436 Return TRUE if we were successful at converting the the block. */
1439 find_if_block (test_bb, then_edge, else_edge)
1440 basic_block test_bb;
1441 edge then_edge, else_edge;
1443 basic_block then_bb = then_edge->dest;
1444 basic_block else_bb = else_edge->dest;
1445 basic_block join_bb = NULL_BLOCK;
1446 edge then_succ = then_bb->succ;
1447 edge else_succ = else_bb->succ;
1450 /* The THEN block of an IF-THEN combo must have exactly one predecessor. */
1451 if (then_bb->pred->pred_next != NULL_EDGE)
1454 /* The THEN block of an IF-THEN combo must have exactly one successor. */
1455 if (then_succ == NULL_EDGE
1456 || then_succ->succ_next != NULL_EDGE
1457 || (then_succ->flags & EDGE_COMPLEX))
1460 /* If the THEN block's successor is the other edge out of the TEST block,
1461 then we have an IF-THEN combo without an ELSE. */
1462 if (then_succ->dest == else_bb)
1465 else_bb = NULL_BLOCK;
1468 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
1469 has exactly one predecessor and one successor, and the outgoing edge
1470 is not complex, then we have an IF-THEN-ELSE combo. */
1471 else if (else_succ != NULL_EDGE
1472 && then_succ->dest == else_succ->dest
1473 && else_bb->pred->pred_next == NULL_EDGE
1474 && else_succ->succ_next == NULL_EDGE
1475 && ! (else_succ->flags & EDGE_COMPLEX))
1476 join_bb = else_succ->dest;
1478 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
1482 num_possible_if_blocks++;
1487 fprintf (rtl_dump_file,
1488 "\nIF-THEN-ELSE block found, start %d, then %d, else %d, join %d\n",
1489 test_bb->index, then_bb->index, else_bb->index,
1492 fprintf (rtl_dump_file,
1493 "\nIF-THEN block found, start %d, then %d, join %d\n",
1494 test_bb->index, then_bb->index, join_bb->index);
1497 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we
1498 get the first condition for free, since we've already asserted that
1499 there's a fallthru edge from IF to THEN. */
1500 /* ??? As an enhancement, move the ELSE block. Have to deal with EH and
1501 BLOCK notes, if by no other means than aborting the merge if they
1502 exist. Sticky enough I don't want to think about it now. */
1503 next_index = then_bb->index;
1504 if (else_bb && ++next_index != else_bb->index)
1506 if (++next_index != join_bb->index)
1514 /* Do the real work. */
1515 return process_if_block (test_bb, then_bb, else_bb, join_bb);
1518 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
1519 transformable, but not necessarily the other. There need be no
1522 Return TRUE if we were successful at converting the the block.
1524 Cases we'd like to look at:
1527 if (test) goto over; // x not live
1535 if (! test) goto label;
1538 if (test) goto E; // x not live
1552 (3) // This one's really only interesting for targets that can do
1553 // multiway branching, e.g. IA-64 BBB bundles. For other targets
1554 // it results in multiple branches on a cache line, which often
1555 // does not sit well with predictors.
1557 if (test1) goto E; // predicted not taken
1573 (A) Don't do (2) if the branch is predicted against the block we're
1574 eliminating. Do it anyway if we can eliminate a branch; this requires
1575 that the sole successor of the eliminated block postdominate the other
1578 (B) With CE, on (3) we can steal from both sides of the if, creating
1587 Again, this is most useful if J postdominates.
1589 (C) CE substitutes for helpful life information.
1591 (D) These heuristics need a lot of work. */
1593 /* Tests for case 1 above. */
1596 find_if_case_1 (test_bb, then_edge, else_edge)
1597 basic_block test_bb;
1598 edge then_edge, else_edge;
1600 basic_block then_bb = then_edge->dest;
1601 basic_block else_bb = else_edge->dest;
1602 edge then_succ = then_bb->succ;
1605 /* THEN has one successor. */
1606 if (!then_succ || then_succ->succ_next != NULL)
1609 /* THEN does not fall through, but is not strange either. */
1610 if (then_succ->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
1613 /* THEN has one predecessor. */
1614 if (then_bb->pred->pred_next != NULL)
1617 /* ELSE follows THEN. (??? could be moved) */
1618 if (else_bb->index != then_bb->index + 1)
1621 num_possible_if_blocks++;
1623 fprintf (rtl_dump_file,
1624 "\nIF-CASE-1 found, start %d, then %d\n",
1625 test_bb->index, then_bb->index);
1627 /* THEN is small. */
1628 if (count_bb_insns (then_bb) > BRANCH_COST)
1631 /* Find the label for THEN's destination. */
1632 if (then_succ->dest == EXIT_BLOCK_PTR)
1636 new_lab = JUMP_LABEL (then_bb->end);
1641 /* Registers set are dead, or are predicable. */
1642 if (! dead_or_predicable (test_bb, then_bb, else_bb, new_lab, 1))
1645 /* Conversion went ok, including moving the insns and fixing up the
1646 jump. Adjust the CFG to match. */
1648 SET_UPDATE_LIFE (test_bb);
1649 bitmap_operation (test_bb->global_live_at_end,
1650 else_bb->global_live_at_start,
1651 then_bb->global_live_at_end, BITMAP_IOR);
1653 make_edge (NULL, test_bb, then_succ->dest, 0);
1654 flow_delete_block (then_bb);
1655 tidy_fallthru_edge (else_edge, test_bb, else_bb);
1657 num_removed_blocks++;
1658 num_updated_if_blocks++;
1663 /* Test for case 2 above. */
1666 find_if_case_2 (test_bb, then_edge, else_edge)
1667 basic_block test_bb;
1668 edge then_edge, else_edge;
1670 basic_block then_bb = then_edge->dest;
1671 basic_block else_bb = else_edge->dest;
1672 edge else_succ = else_bb->succ;
1675 /* ELSE has one successor. */
1676 if (!else_succ || else_succ->succ_next != NULL)
1679 /* ELSE outgoing edge is not complex. */
1680 if (else_succ->flags & EDGE_COMPLEX)
1683 /* ELSE has one predecessor. */
1684 if (else_bb->pred->pred_next != NULL)
1687 /* THEN is not EXIT. */
1688 if (then_bb->index < 0)
1691 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
1692 note = find_reg_note (test_bb->end, REG_BR_PROB, NULL_RTX);
1693 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
1695 else if (else_succ->dest->index < 0
1696 || TEST_BIT (post_dominators[ORIG_INDEX (then_bb)],
1697 ORIG_INDEX (else_succ->dest)))
1702 num_possible_if_blocks++;
1704 fprintf (rtl_dump_file,
1705 "\nIF-CASE-2 found, start %d, else %d\n",
1706 test_bb->index, else_bb->index);
1708 /* ELSE is small. */
1709 if (count_bb_insns (then_bb) > BRANCH_COST)
1712 /* Find the label for ELSE's destination. */
1713 if (else_succ->dest == EXIT_BLOCK_PTR)
1717 if (else_succ->flags & EDGE_FALLTHRU)
1719 new_lab = else_succ->dest->head;
1720 if (GET_CODE (new_lab) != CODE_LABEL)
1725 new_lab = JUMP_LABEL (else_bb->end);
1731 /* Registers set are dead, or are predicable. */
1732 if (! dead_or_predicable (test_bb, else_bb, then_bb, new_lab, 0))
1735 /* Conversion went ok, including moving the insns and fixing up the
1736 jump. Adjust the CFG to match. */
1738 SET_UPDATE_LIFE (test_bb);
1739 bitmap_operation (test_bb->global_live_at_end,
1740 then_bb->global_live_at_start,
1741 else_bb->global_live_at_end, BITMAP_IOR);
1743 remove_edge (else_edge);
1744 make_edge (NULL, test_bb, else_succ->dest, 0);
1745 flow_delete_block (else_bb);
1747 num_removed_blocks++;
1748 num_updated_if_blocks++;
1750 /* ??? We may now fallthru from one of THEN's successors into a join
1751 block. Rerun cleanup_cfg? Examine things manually? Wait? */
1756 /* A subroutine of dead_or_predicable called through for_each_rtx.
1757 Return 1 if a memory is found. */
1760 find_memory (px, data)
1762 void *data ATTRIBUTE_UNUSED;
1764 return GET_CODE (*px) == MEM;
1767 /* Used by the code above to perform the actual rtl transformations.
1768 Return TRUE if successful.
1770 TEST_BB is the block containing the conditional branch. MERGE_BB
1771 is the block containing the code to manipulate. NEW_DEST is the
1772 label TEST_BB should be branching to after the conversion.
1773 REVERSEP is true if the sense of the branch should be reversed. */
1776 dead_or_predicable (test_bb, merge_bb, other_bb, new_dest, reversep)
1777 basic_block test_bb, merge_bb, other_bb;
1781 rtx head, end, jump, earliest, old_dest;
1783 jump = test_bb->end;
1785 /* Find the extent of the real code in the merge block. */
1786 head = merge_bb->head;
1787 end = merge_bb->end;
1789 if (GET_CODE (head) == CODE_LABEL)
1790 head = NEXT_INSN (head);
1791 if (GET_CODE (head) == NOTE)
1795 head = end = NULL_RTX;
1798 head = NEXT_INSN (head);
1801 if (GET_CODE (end) == JUMP_INSN)
1805 head = end = NULL_RTX;
1808 end = PREV_INSN (end);
1811 if (HAVE_conditional_execution)
1813 /* In the conditional execution case, we have things easy. We know
1814 the condition is reversable. We don't have to check life info,
1815 becase we're going to conditionally execute the code anyway.
1816 All that's left is making sure the insns involved can actually
1821 cond = cond_exec_get_condition (jump);
1823 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
1825 prob_val = XEXP (prob_val, 0);
1829 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
1830 GET_MODE (cond), XEXP (cond, 0),
1833 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
1836 if (! cond_exec_process_insns (head, end, cond, prob_val, 0))
1843 /* In the non-conditional execution case, we have to verify that there
1844 are no trapping operations, no calls, no references to memory, and
1845 that any registers modified are dead at the branch site. */
1847 rtx insn, cond, prev;
1848 regset_head merge_set_head, tmp_head, test_live_head, test_set_head;
1849 regset merge_set, tmp, test_live, test_set;
1850 struct propagate_block_info *pbi;
1853 /* Check for no calls or trapping operations. */
1854 for (insn = head; ; insn = NEXT_INSN (insn))
1856 if (GET_CODE (insn) == CALL_INSN)
1860 if (may_trap_p (PATTERN (insn)))
1863 /* ??? Even non-trapping memories such as stack frame
1864 references must be avoided. For stores, we collect
1865 no lifetime info; for reads, we'd have to assert
1866 true_dependance false against every store in the
1868 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
1875 if (! any_condjump_p (jump))
1878 /* Find the extent of the conditional. */
1879 cond = noce_get_condition (jump, &earliest);
1884 MERGE_SET = set of registers set in MERGE_BB
1885 TEST_LIVE = set of registers live at EARLIEST
1886 TEST_SET = set of registers set between EARLIEST and the
1887 end of the block. */
1889 tmp = INITIALIZE_REG_SET (tmp_head);
1890 merge_set = INITIALIZE_REG_SET (merge_set_head);
1891 test_live = INITIALIZE_REG_SET (test_live_head);
1892 test_set = INITIALIZE_REG_SET (test_set_head);
1894 /* ??? bb->local_set is only valid during calculate_global_regs_live,
1895 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
1896 since we've already asserted that MERGE_BB is small. */
1897 propagate_block (merge_bb, tmp, merge_set, 0);
1899 /* For small register class machines, don't lengthen lifetimes of
1900 hard registers before reload. */
1901 if (SMALL_REGISTER_CLASSES && ! reload_completed)
1903 EXECUTE_IF_SET_IN_BITMAP
1906 if (i < FIRST_PSEUDO_REGISTER
1908 && ! global_regs[i])
1913 /* For TEST, we're interested in a range of insns, not a whole block.
1914 Moreover, we're interested in the insns live from OTHER_BB. */
1916 COPY_REG_SET (test_live, other_bb->global_live_at_start);
1917 pbi = init_propagate_block_info (test_bb, test_live, test_set, 0);
1919 for (insn = jump; ; insn = prev)
1921 prev = propagate_one_insn (pbi, insn);
1922 if (insn == earliest)
1926 free_propagate_block_info (pbi);
1928 /* We can perform the transformation if
1929 MERGE_SET & (TEST_SET | TEST_LIVE)
1931 TEST_SET & merge_bb->global_live_at_start
1934 bitmap_operation (tmp, test_set, test_live, BITMAP_IOR);
1935 bitmap_operation (tmp, tmp, merge_set, BITMAP_AND);
1936 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
1938 bitmap_operation (tmp, test_set, merge_bb->global_live_at_start,
1940 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
1943 FREE_REG_SET (merge_set);
1944 FREE_REG_SET (test_live);
1945 FREE_REG_SET (test_set);
1952 /* We don't want to use normal invert_jump or redirect_jump because
1953 we don't want to delete_insn called. Also, we want to do our own
1954 change group management. */
1956 old_dest = JUMP_LABEL (jump);
1958 ? ! invert_jump_1 (jump, new_dest)
1959 : ! redirect_jump_1 (jump, new_dest))
1962 if (! apply_change_group ())
1966 LABEL_NUSES (old_dest) -= 1;
1968 LABEL_NUSES (new_dest) += 1;
1969 JUMP_LABEL (jump) = new_dest;
1973 rtx note = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
1975 XEXP (note, 0) = GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (note, 0)));
1978 /* Move the insns out of MERGE_BB to before the branch. */
1981 if (end == merge_bb->end)
1982 merge_bb->end = PREV_INSN (head);
1984 head = squeeze_notes (head, end);
1985 if (GET_CODE (end) == NOTE
1986 && (NOTE_LINE_NUMBER (end) == NOTE_INSN_BLOCK_END
1987 || NOTE_LINE_NUMBER (end) == NOTE_INSN_BLOCK_BEG
1988 || NOTE_LINE_NUMBER (end) == NOTE_INSN_LOOP_BEG
1989 || NOTE_LINE_NUMBER (end) == NOTE_INSN_LOOP_END
1990 || NOTE_LINE_NUMBER (end) == NOTE_INSN_LOOP_CONT
1991 || NOTE_LINE_NUMBER (end) == NOTE_INSN_LOOP_VTOP))
1995 end = PREV_INSN (end);
1998 reorder_insns (head, end, PREV_INSN (earliest));
2007 /* Main entry point for all if-conversion. */
2010 if_convert (life_data_ok)
2015 num_possible_if_blocks = 0;
2016 num_updated_if_blocks = 0;
2017 num_removed_blocks = 0;
2019 /* Free up basic_block_for_insn so that we don't have to keep it
2020 up to date, either here or in merge_blocks_nomove. */
2021 free_basic_block_vars (1);
2023 /* Compute postdominators if we think we'll use them. */
2024 post_dominators = NULL;
2025 if (HAVE_conditional_execution || life_data_ok)
2027 post_dominators = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
2028 compute_flow_dominators (NULL, post_dominators);
2031 /* Record initial block numbers. */
2032 for (block_num = 0; block_num < n_basic_blocks; block_num++)
2033 SET_ORIG_INDEX (BASIC_BLOCK (block_num), block_num);
2035 /* Go through each of the basic blocks looking for things to convert. */
2036 for (block_num = 0; block_num < n_basic_blocks; )
2038 basic_block bb = BASIC_BLOCK (block_num);
2039 if (find_if_header (bb))
2040 block_num = bb->index;
2045 if (post_dominators)
2046 sbitmap_vector_free (post_dominators);
2049 fflush (rtl_dump_file);
2051 /* Rebuild basic_block_for_insn for update_life_info and for gcse. */
2052 compute_bb_for_insn (get_max_uid ());
2054 /* Rebuild life info for basic blocks that require it. */
2055 if (num_removed_blocks && life_data_ok)
2057 sbitmap update_life_blocks = sbitmap_alloc (n_basic_blocks);
2058 sbitmap_zero (update_life_blocks);
2060 /* If we allocated new pseudos, we must resize the array for sched1. */
2061 if (max_regno < max_reg_num ())
2063 max_regno = max_reg_num ();
2064 allocate_reg_info (max_regno, FALSE, FALSE);
2067 for (block_num = 0; block_num < n_basic_blocks; block_num++)
2068 if (UPDATE_LIFE (BASIC_BLOCK (block_num)))
2069 SET_BIT (update_life_blocks, block_num);
2071 count_or_remove_death_notes (update_life_blocks, 1);
2072 /* ??? See about adding a mode that verifies that the initial
2073 set of blocks don't let registers come live. */
2074 update_life_info (update_life_blocks, UPDATE_LIFE_GLOBAL,
2075 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2076 | PROP_KILL_DEAD_CODE);
2078 sbitmap_free (update_life_blocks);
2081 /* Write the final stats. */
2082 if (rtl_dump_file && num_possible_if_blocks > 0)
2084 fprintf (rtl_dump_file,
2085 "\n%d possible IF blocks searched.\n",
2086 num_possible_if_blocks);
2087 fprintf (rtl_dump_file,
2088 "%d IF blocks converted.\n",
2089 num_updated_if_blocks);
2090 fprintf (rtl_dump_file,
2091 "%d basic blocks deleted.\n\n\n",
2092 num_removed_blocks);
2095 #ifdef ENABLE_CHECKING
2096 verify_flow_info ();