1 /* If-conversion support.
2 Copyright (C) 2000, 2001 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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, basic_block, 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)))
117 #define ORIG_INDEX(BB) ((size_t)(BB)->aux)
120 /* Count the number of non-jump active insns in BB. */
131 if (GET_CODE (insn) == CALL_INSN || GET_CODE (insn) == INSN)
136 insn = NEXT_INSN (insn);
142 /* Return the first non-jump active insn in the basic block. */
145 first_active_insn (bb)
150 if (GET_CODE (insn) == CODE_LABEL)
154 insn = NEXT_INSN (insn);
157 while (GET_CODE (insn) == NOTE)
161 insn = NEXT_INSN (insn);
164 if (GET_CODE (insn) == JUMP_INSN)
170 /* Return true if INSN is the last active non-jump insn in BB. */
173 last_active_insn_p (bb, insn)
181 insn = NEXT_INSN (insn);
183 while (GET_CODE (insn) == NOTE);
185 return GET_CODE (insn) == JUMP_INSN;
188 /* It is possible, especially when having dealt with multi-word
189 arithmetic, for the expanders to have emitted jumps. Search
190 through the sequence and return TRUE if a jump exists so that
191 we can abort the conversion. */
194 seq_contains_jump (insn)
199 if (GET_CODE (insn) == JUMP_INSN)
201 insn = NEXT_INSN (insn);
206 /* Go through a bunch of insns, converting them to conditional
207 execution format if possible. Return TRUE if all of the non-note
208 insns were processed. */
211 cond_exec_process_insns (start, end, test, prob_val, mod_ok)
212 rtx start; /* first insn to look at */
213 rtx end; /* last insn to look at */
214 rtx test; /* conditional execution test */
215 rtx prob_val; /* probability of branch taken. */
216 int mod_ok; /* true if modifications ok last insn. */
218 int must_be_last = FALSE;
222 for (insn = start; ; insn = NEXT_INSN (insn))
224 if (GET_CODE (insn) == NOTE)
227 if (GET_CODE (insn) != INSN && GET_CODE (insn) != CALL_INSN)
230 /* Remove USE insns that get in the way. */
231 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
233 /* ??? Ug. Actually unlinking the thing is problematic,
234 given what we'd have to coordinate with our callers. */
235 PUT_CODE (insn, NOTE);
236 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
237 NOTE_SOURCE_FILE (insn) = 0;
241 /* Last insn wasn't last? */
245 if (modified_in_p (test, insn))
252 /* Now build the conditional form of the instruction. */
253 pattern = PATTERN (insn);
255 /* If the machine needs to modify the insn being conditionally executed,
256 say for example to force a constant integer operand into a temp
257 register, do so here. */
258 #ifdef IFCVT_MODIFY_INSN
259 IFCVT_MODIFY_INSN (pattern, insn);
264 validate_change (insn, &PATTERN (insn),
265 gen_rtx_COND_EXEC (VOIDmode, copy_rtx (test),
268 if (GET_CODE (insn) == CALL_INSN && prob_val)
269 validate_change (insn, ®_NOTES (insn),
270 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
271 REG_NOTES (insn)), 1);
281 /* Return the condition for a jump. Do not do any special processing. */
284 cond_exec_get_condition (jump)
289 if (any_condjump_p (jump))
290 test_if = SET_SRC (pc_set (jump));
293 cond = XEXP (test_if, 0);
295 /* If this branches to JUMP_LABEL when the condition is false,
296 reverse the condition. */
297 if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF
298 && XEXP (XEXP (test_if, 2), 0) == JUMP_LABEL (jump))
300 enum rtx_code rev = reversed_comparison_code (cond, jump);
304 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
311 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
312 to conditional execution. Return TRUE if we were successful at
313 converting the the block. */
316 cond_exec_process_if_block (test_bb, then_bb, else_bb, join_bb)
317 basic_block test_bb; /* Basic block test is in */
318 basic_block then_bb; /* Basic block for THEN block */
319 basic_block else_bb; /* Basic block for ELSE block */
320 basic_block join_bb; /* Basic block the join label is in */
322 rtx test_expr; /* expression in IF_THEN_ELSE that is tested */
323 rtx then_start; /* first insn in THEN block */
324 rtx then_end; /* last insn + 1 in THEN block */
325 rtx else_start = NULL_RTX; /* first insn in ELSE block or NULL */
326 rtx else_end = NULL_RTX; /* last insn + 1 in ELSE block */
327 int max; /* max # of insns to convert. */
328 int then_mod_ok; /* whether conditional mods are ok in THEN */
329 rtx true_expr; /* test for else block insns */
330 rtx false_expr; /* test for then block insns */
331 rtx true_prob_val; /* probability of else block */
332 rtx false_prob_val; /* probability of then block */
334 enum rtx_code false_code;
336 /* Find the conditional jump to the ELSE or JOIN part, and isolate
338 test_expr = cond_exec_get_condition (test_bb->end);
342 /* If the conditional jump is more than just a conditional jump,
343 then we can not do conditional execution conversion on this block. */
344 if (!onlyjump_p (test_bb->end))
347 /* Collect the bounds of where we're to search. */
349 then_start = then_bb->head;
350 then_end = then_bb->end;
352 /* Skip a label heading THEN block. */
353 if (GET_CODE (then_start) == CODE_LABEL)
354 then_start = NEXT_INSN (then_start);
356 /* Skip a (use (const_int 0)) or branch as the final insn. */
357 if (GET_CODE (then_end) == INSN
358 && GET_CODE (PATTERN (then_end)) == USE
359 && GET_CODE (XEXP (PATTERN (then_end), 0)) == CONST_INT)
360 then_end = PREV_INSN (then_end);
361 else if (GET_CODE (then_end) == JUMP_INSN)
362 then_end = PREV_INSN (then_end);
366 /* Skip the ELSE block's label. */
367 else_start = NEXT_INSN (else_bb->head);
368 else_end = else_bb->end;
370 /* Skip a (use (const_int 0)) or branch as the final insn. */
371 if (GET_CODE (else_end) == INSN
372 && GET_CODE (PATTERN (else_end)) == USE
373 && GET_CODE (XEXP (PATTERN (else_end), 0)) == CONST_INT)
374 else_end = PREV_INSN (else_end);
375 else if (GET_CODE (else_end) == JUMP_INSN)
376 else_end = PREV_INSN (else_end);
379 /* How many instructions should we convert in total? */
383 max = 2 * MAX_CONDITIONAL_EXECUTE;
384 n_insns = count_bb_insns (else_bb);
387 max = MAX_CONDITIONAL_EXECUTE;
388 n_insns += count_bb_insns (then_bb);
392 /* Map test_expr/test_jump into the appropriate MD tests to use on
393 the conditionally executed code. */
395 true_expr = test_expr;
397 false_code = reversed_comparison_code (true_expr, test_bb->end);
398 if (false_code != UNKNOWN)
399 false_expr = gen_rtx_fmt_ee (false_code, GET_MODE (true_expr),
400 XEXP (true_expr, 0), XEXP (true_expr, 1));
402 false_expr = NULL_RTX;
404 #ifdef IFCVT_MODIFY_TESTS
405 /* If the machine description needs to modify the tests, such as setting a
406 conditional execution register from a comparison, it can do so here. */
407 IFCVT_MODIFY_TESTS (true_expr, false_expr, test_bb, then_bb, else_bb,
410 /* See if the conversion failed */
411 if (!true_expr || !false_expr)
415 true_prob_val = find_reg_note (test_bb->end, REG_BR_PROB, NULL_RTX);
418 true_prob_val = XEXP (true_prob_val, 0);
419 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
422 false_prob_val = NULL_RTX;
424 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
425 on then THEN block. */
426 then_mod_ok = (else_bb == NULL_BLOCK);
428 /* Go through the THEN and ELSE blocks converting the insns if possible
429 to conditional execution. */
433 || ! cond_exec_process_insns (then_start, then_end, false_expr,
434 false_prob_val, then_mod_ok)))
438 && ! cond_exec_process_insns (else_start, else_end,
439 true_expr, true_prob_val, TRUE))
442 if (! apply_change_group ())
445 #ifdef IFCVT_MODIFY_FINAL
446 /* Do any machine dependent final modifications */
447 IFCVT_MODIFY_FINAL (test_bb, then_bb, else_bb, join_bb);
450 /* Conversion succeeded. */
452 fprintf (rtl_dump_file, "%d insn%s converted to conditional execution.\n",
453 n_insns, (n_insns == 1) ? " was" : "s were");
455 /* Merge the blocks! */
456 merge_if_block (test_bb, then_bb, else_bb, join_bb);
460 #ifdef IFCVT_MODIFY_CANCEL
461 /* Cancel any machine dependent changes. */
462 IFCVT_MODIFY_CANCEL (test_bb, then_bb, else_bb, join_bb);
469 /* Used by noce_process_if_block to communicate with its subroutines.
471 The subroutines know that A and B may be evaluated freely. They
472 know that X is a register. They should insert new instructions
473 before cond_earliest. */
480 rtx jump, cond, cond_earliest;
483 static rtx noce_emit_store_flag PARAMS ((struct noce_if_info *,
485 static int noce_try_store_flag PARAMS ((struct noce_if_info *));
486 static int noce_try_store_flag_inc PARAMS ((struct noce_if_info *));
487 static int noce_try_store_flag_constants PARAMS ((struct noce_if_info *));
488 static int noce_try_store_flag_mask PARAMS ((struct noce_if_info *));
489 static rtx noce_emit_cmove PARAMS ((struct noce_if_info *,
490 rtx, enum rtx_code, rtx,
492 static int noce_try_cmove PARAMS ((struct noce_if_info *));
493 static int noce_try_cmove_arith PARAMS ((struct noce_if_info *));
494 static rtx noce_get_alt_condition PARAMS ((struct noce_if_info *,
496 static int noce_try_minmax PARAMS ((struct noce_if_info *));
497 static int noce_try_abs PARAMS ((struct noce_if_info *));
499 /* Helper function for noce_try_store_flag*. */
502 noce_emit_store_flag (if_info, x, reversep, normalize)
503 struct noce_if_info *if_info;
505 int reversep, normalize;
507 rtx cond = if_info->cond;
511 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
512 || ! general_operand (XEXP (cond, 1), VOIDmode));
514 /* If earliest == jump, or when the condition is complex, try to
515 build the store_flag insn directly. */
518 cond = XEXP (SET_SRC (pc_set (if_info->jump)), 0);
521 code = reversed_comparison_code (cond, if_info->jump);
523 code = GET_CODE (cond);
525 if ((if_info->cond_earliest == if_info->jump || cond_complex)
526 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
530 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
532 tmp = gen_rtx_SET (VOIDmode, x, tmp);
535 tmp = emit_insn (tmp);
537 if (recog_memoized (tmp) >= 0)
543 if_info->cond_earliest = if_info->jump;
551 /* Don't even try if the comparison operands are weird. */
555 return emit_store_flag (x, code, XEXP (cond, 0),
556 XEXP (cond, 1), VOIDmode,
557 (code == LTU || code == LEU
558 || code == GEU || code == GTU), normalize);
561 /* Emit instruction to move an rtx into STRICT_LOW_PART. */
563 noce_emit_move_insn (x, y)
566 enum machine_mode outmode, inmode;
570 if (GET_CODE (x) != STRICT_LOW_PART)
572 emit_move_insn (x, y);
577 inner = XEXP (outer, 0);
578 outmode = GET_MODE (outer);
579 inmode = GET_MODE (inner);
580 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
581 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y,
582 GET_MODE_BITSIZE (inmode));
585 /* Convert "if (test) x = 1; else x = 0".
587 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
588 tried in noce_try_store_flag_constants after noce_try_cmove has had
589 a go at the conversion. */
592 noce_try_store_flag (if_info)
593 struct noce_if_info *if_info;
598 if (GET_CODE (if_info->b) == CONST_INT
599 && INTVAL (if_info->b) == STORE_FLAG_VALUE
600 && if_info->a == const0_rtx)
602 else if (if_info->b == const0_rtx
603 && GET_CODE (if_info->a) == CONST_INT
604 && INTVAL (if_info->a) == STORE_FLAG_VALUE
605 && (reversed_comparison_code (if_info->cond, if_info->jump)
613 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
616 if (target != if_info->x)
617 noce_emit_move_insn (if_info->x, target);
621 emit_insns_before (seq, if_info->cond_earliest);
632 /* Convert "if (test) x = a; else x = b", for A and B constant. */
635 noce_try_store_flag_constants (if_info)
636 struct noce_if_info *if_info;
640 HOST_WIDE_INT itrue, ifalse, diff, tmp;
641 int normalize, can_reverse;
642 enum machine_mode mode;
645 && GET_CODE (if_info->a) == CONST_INT
646 && GET_CODE (if_info->b) == CONST_INT)
648 mode = GET_MODE (if_info->x);
649 ifalse = INTVAL (if_info->a);
650 itrue = INTVAL (if_info->b);
652 /* Make sure we can represent the difference between the two values. */
653 if ((itrue - ifalse > 0)
654 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
657 diff = trunc_int_for_mode (itrue - ifalse, mode);
659 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
663 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
665 else if (ifalse == 0 && exact_log2 (itrue) >= 0
666 && (STORE_FLAG_VALUE == 1
667 || BRANCH_COST >= 2))
669 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
670 && (STORE_FLAG_VALUE == 1 || BRANCH_COST >= 2))
671 normalize = 1, reversep = 1;
673 && (STORE_FLAG_VALUE == -1
674 || BRANCH_COST >= 2))
676 else if (ifalse == -1 && can_reverse
677 && (STORE_FLAG_VALUE == -1 || BRANCH_COST >= 2))
678 normalize = -1, reversep = 1;
679 else if ((BRANCH_COST >= 2 && STORE_FLAG_VALUE == -1)
687 tmp = itrue; itrue = ifalse; ifalse = tmp;
688 diff = trunc_int_for_mode (-diff, mode);
692 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
699 /* if (test) x = 3; else x = 4;
700 => x = 3 + (test == 0); */
701 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
703 target = expand_simple_binop (mode,
704 (diff == STORE_FLAG_VALUE
706 GEN_INT (ifalse), target, if_info->x, 0,
710 /* if (test) x = 8; else x = 0;
711 => x = (test != 0) << 3; */
712 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
714 target = expand_simple_binop (mode, ASHIFT,
715 target, GEN_INT (tmp), if_info->x, 0,
719 /* if (test) x = -1; else x = b;
720 => x = -(test != 0) | b; */
721 else if (itrue == -1)
723 target = expand_simple_binop (mode, IOR,
724 target, GEN_INT (ifalse), if_info->x, 0,
728 /* if (test) x = a; else x = b;
729 => x = (-(test != 0) & (b - a)) + a; */
732 target = expand_simple_binop (mode, AND,
733 target, GEN_INT (diff), if_info->x, 0,
736 target = expand_simple_binop (mode, PLUS,
737 target, GEN_INT (ifalse),
738 if_info->x, 0, OPTAB_WIDEN);
747 if (target != if_info->x)
748 noce_emit_move_insn (if_info->x, target);
753 if (seq_contains_jump (seq))
756 emit_insns_before (seq, if_info->cond_earliest);
764 /* Convert "if (test) foo++" into "foo += (test != 0)", and
765 similarly for "foo--". */
768 noce_try_store_flag_inc (if_info)
769 struct noce_if_info *if_info;
772 int subtract, normalize;
778 /* Should be no `else' case to worry about. */
779 && if_info->b == if_info->x
780 && GET_CODE (if_info->a) == PLUS
781 && (XEXP (if_info->a, 1) == const1_rtx
782 || XEXP (if_info->a, 1) == constm1_rtx)
783 && rtx_equal_p (XEXP (if_info->a, 0), if_info->x)
784 && (reversed_comparison_code (if_info->cond, if_info->jump)
787 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
788 subtract = 0, normalize = 0;
789 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
790 subtract = 1, normalize = 0;
792 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
796 target = noce_emit_store_flag (if_info,
797 gen_reg_rtx (GET_MODE (if_info->x)),
801 target = expand_simple_binop (GET_MODE (if_info->x),
802 subtract ? MINUS : PLUS,
803 if_info->x, target, if_info->x,
807 if (target != if_info->x)
808 noce_emit_move_insn (if_info->x, target);
813 if (seq_contains_jump (seq))
816 emit_insns_before (seq, if_info->cond_earliest);
827 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
830 noce_try_store_flag_mask (if_info)
831 struct noce_if_info *if_info;
839 || STORE_FLAG_VALUE == -1)
840 && ((if_info->a == const0_rtx
841 && rtx_equal_p (if_info->b, if_info->x))
842 || ((reversep = (reversed_comparison_code (if_info->cond,
845 && if_info->b == const0_rtx
846 && rtx_equal_p (if_info->a, if_info->x))))
849 target = noce_emit_store_flag (if_info,
850 gen_reg_rtx (GET_MODE (if_info->x)),
853 target = expand_simple_binop (GET_MODE (if_info->x), AND,
854 if_info->x, target, if_info->x, 0,
859 if (target != if_info->x)
860 noce_emit_move_insn (if_info->x, target);
865 if (seq_contains_jump (seq))
868 emit_insns_before (seq, if_info->cond_earliest);
879 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
882 noce_emit_cmove (if_info, x, code, cmp_a, cmp_b, vfalse, vtrue)
883 struct noce_if_info *if_info;
884 rtx x, cmp_a, cmp_b, vfalse, vtrue;
887 /* If earliest == jump, try to build the cmove insn directly.
888 This is helpful when combine has created some complex condition
889 (like for alpha's cmovlbs) that we can't hope to regenerate
890 through the normal interface. */
892 if (if_info->cond_earliest == if_info->jump)
896 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
897 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
898 tmp = gen_rtx_SET (VOIDmode, x, tmp);
901 tmp = emit_insn (tmp);
903 if (recog_memoized (tmp) >= 0)
915 /* Don't even try if the comparison operands are weird. */
916 if (! general_operand (cmp_a, GET_MODE (cmp_a))
917 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
920 #if HAVE_conditional_move
921 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
922 vtrue, vfalse, GET_MODE (x),
923 (code == LTU || code == GEU
924 || code == LEU || code == GTU));
926 /* We'll never get here, as noce_process_if_block doesn't call the
927 functions involved. Ifdef code, however, should be discouraged
928 because it leads to typos in the code not selected. However,
929 emit_conditional_move won't exist either. */
934 /* Try only simple constants and registers here. More complex cases
935 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
936 has had a go at it. */
939 noce_try_cmove (if_info)
940 struct noce_if_info *if_info;
945 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
946 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
950 code = GET_CODE (if_info->cond);
951 target = noce_emit_cmove (if_info, if_info->x, code,
952 XEXP (if_info->cond, 0),
953 XEXP (if_info->cond, 1),
954 if_info->a, if_info->b);
958 if (target != if_info->x)
959 noce_emit_move_insn (if_info->x, target);
963 emit_insns_before (seq, if_info->cond_earliest);
976 /* Try more complex cases involving conditional_move. */
979 noce_try_cmove_arith (if_info)
980 struct noce_if_info *if_info;
990 /* A conditional move from two memory sources is equivalent to a
991 conditional on their addresses followed by a load. Don't do this
992 early because it'll screw alias analysis. Note that we've
993 already checked for no side effects. */
994 if (! no_new_pseudos && cse_not_expected
995 && GET_CODE (a) == MEM && GET_CODE (b) == MEM
1000 x = gen_reg_rtx (Pmode);
1004 /* ??? We could handle this if we knew that a load from A or B could
1005 not fault. This is also true if we've already loaded
1006 from the address along the path from ENTRY. */
1007 else if (may_trap_p (a) || may_trap_p (b))
1010 /* if (test) x = a + b; else x = c - d;
1017 code = GET_CODE (if_info->cond);
1018 insn_a = if_info->insn_a;
1019 insn_b = if_info->insn_b;
1021 /* Possibly rearrange operands to make things come out more natural. */
1022 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1025 if (rtx_equal_p (b, x))
1027 else if (general_operand (b, GET_MODE (b)))
1032 code = reversed_comparison_code (if_info->cond, if_info->jump);
1033 tmp = a, a = b, b = tmp;
1034 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1040 /* If either operand is complex, load it into a register first.
1041 The best way to do this is to copy the original insn. In this
1042 way we preserve any clobbers etc that the insn may have had.
1043 This is of course not possible in the IS_MEM case. */
1044 if (! general_operand (a, GET_MODE (a)))
1049 goto end_seq_and_fail;
1053 tmp = gen_reg_rtx (GET_MODE (a));
1054 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1057 goto end_seq_and_fail;
1060 a = gen_reg_rtx (GET_MODE (a));
1061 tmp = copy_rtx (insn_a);
1062 set = single_set (tmp);
1064 tmp = emit_insn (PATTERN (tmp));
1066 if (recog_memoized (tmp) < 0)
1067 goto end_seq_and_fail;
1069 if (! general_operand (b, GET_MODE (b)))
1074 goto end_seq_and_fail;
1078 tmp = gen_reg_rtx (GET_MODE (b));
1079 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, b));
1082 goto end_seq_and_fail;
1085 b = gen_reg_rtx (GET_MODE (b));
1086 tmp = copy_rtx (insn_b);
1087 set = single_set (tmp);
1089 tmp = emit_insn (PATTERN (tmp));
1091 if (recog_memoized (tmp) < 0)
1092 goto end_seq_and_fail;
1095 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1096 XEXP (if_info->cond, 1), a, b);
1099 goto end_seq_and_fail;
1101 /* If we're handling a memory for above, emit the load now. */
1104 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1106 /* Copy over flags as appropriate. */
1107 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1108 MEM_VOLATILE_P (tmp) = 1;
1109 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1110 MEM_IN_STRUCT_P (tmp) = 1;
1111 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1112 MEM_SCALAR_P (tmp) = 1;
1113 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1114 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1116 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1118 noce_emit_move_insn (if_info->x, tmp);
1120 else if (target != x)
1121 noce_emit_move_insn (x, target);
1125 emit_insns_before (tmp, if_info->cond_earliest);
1133 /* For most cases, the simplified condition we found is the best
1134 choice, but this is not the case for the min/max/abs transforms.
1135 For these we wish to know that it is A or B in the condition. */
1138 noce_get_alt_condition (if_info, target, earliest)
1139 struct noce_if_info *if_info;
1143 rtx cond, set, insn;
1146 /* If target is already mentioned in the known condition, return it. */
1147 if (reg_mentioned_p (target, if_info->cond))
1149 *earliest = if_info->cond_earliest;
1150 return if_info->cond;
1153 set = pc_set (if_info->jump);
1154 cond = XEXP (SET_SRC (set), 0);
1156 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1157 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1159 /* If we're looking for a constant, try to make the conditional
1160 have that constant in it. There are two reasons why it may
1161 not have the constant we want:
1163 1. GCC may have needed to put the constant in a register, because
1164 the target can't compare directly against that constant. For
1165 this case, we look for a SET immediately before the comparison
1166 that puts a constant in that register.
1168 2. GCC may have canonicalized the conditional, for example
1169 replacing "if x < 4" with "if x <= 3". We can undo that (or
1170 make equivalent types of changes) to get the constants we need
1171 if they're off by one in the right direction. */
1173 if (GET_CODE (target) == CONST_INT)
1175 enum rtx_code code = GET_CODE (if_info->cond);
1176 rtx op_a = XEXP (if_info->cond, 0);
1177 rtx op_b = XEXP (if_info->cond, 1);
1180 /* First, look to see if we put a constant in a register. */
1181 prev_insn = PREV_INSN (if_info->cond_earliest);
1183 && INSN_P (prev_insn)
1184 && GET_CODE (PATTERN (prev_insn)) == SET)
1186 rtx src = find_reg_equal_equiv_note (prev_insn);
1188 src = SET_SRC (PATTERN (prev_insn));
1189 if (GET_CODE (src) == CONST_INT)
1191 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1193 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1196 if (GET_CODE (op_a) == CONST_INT)
1201 code = swap_condition (code);
1206 /* Now, look to see if we can get the right constant by
1207 adjusting the conditional. */
1208 if (GET_CODE (op_b) == CONST_INT)
1210 HOST_WIDE_INT desired_val = INTVAL (target);
1211 HOST_WIDE_INT actual_val = INTVAL (op_b);
1216 if (actual_val == desired_val + 1)
1219 op_b = GEN_INT (desired_val);
1223 if (actual_val == desired_val - 1)
1226 op_b = GEN_INT (desired_val);
1230 if (actual_val == desired_val - 1)
1233 op_b = GEN_INT (desired_val);
1237 if (actual_val == desired_val + 1)
1240 op_b = GEN_INT (desired_val);
1248 /* If we made any changes, generate a new conditional that is
1249 equivalent to what we started with, but has the right
1251 if (code != GET_CODE (if_info->cond)
1252 || op_a != XEXP (if_info->cond, 0)
1253 || op_b != XEXP (if_info->cond, 1))
1255 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1256 *earliest = if_info->cond_earliest;
1261 cond = canonicalize_condition (if_info->jump, cond, reverse,
1263 if (! cond || ! reg_mentioned_p (target, cond))
1266 /* We almost certainly searched back to a different place.
1267 Need to re-verify correct lifetimes. */
1269 /* X may not be mentioned in the range (cond_earliest, jump]. */
1270 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1271 if (INSN_P (insn) && reg_mentioned_p (if_info->x, insn))
1274 /* A and B may not be modified in the range [cond_earliest, jump). */
1275 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1277 && (modified_in_p (if_info->a, insn)
1278 || modified_in_p (if_info->b, insn)))
1284 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1287 noce_try_minmax (if_info)
1288 struct noce_if_info *if_info;
1290 rtx cond, earliest, target, seq;
1291 enum rtx_code code, op;
1294 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1298 /* ??? Reject FP modes since we don't know how 0 vs -0 or NaNs
1299 will be resolved with an SMIN/SMAX. It wouldn't be too hard
1300 to get the target to tell us... */
1301 if (FLOAT_MODE_P (GET_MODE (if_info->x))
1302 && TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
1303 && ! flag_unsafe_math_optimizations)
1306 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1310 /* Verify the condition is of the form we expect, and canonicalize
1311 the comparison code. */
1312 code = GET_CODE (cond);
1313 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1315 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1318 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1320 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1322 code = swap_condition (code);
1327 /* Determine what sort of operation this is. Note that the code is for
1328 a taken branch, so the code->operation mapping appears backwards. */
1361 target = expand_simple_binop (GET_MODE (if_info->x), op,
1362 if_info->a, if_info->b,
1363 if_info->x, unsignedp, OPTAB_WIDEN);
1369 if (target != if_info->x)
1370 noce_emit_move_insn (if_info->x, target);
1375 if (seq_contains_jump (seq))
1378 emit_insns_before (seq, earliest);
1379 if_info->cond = cond;
1380 if_info->cond_earliest = earliest;
1385 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1388 noce_try_abs (if_info)
1389 struct noce_if_info *if_info;
1391 rtx cond, earliest, target, seq, a, b, c;
1394 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1398 /* Recognize A and B as constituting an ABS or NABS. */
1401 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1403 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1405 c = a; a = b; b = c;
1411 cond = noce_get_alt_condition (if_info, b, &earliest);
1415 /* Verify the condition is of the form we expect. */
1416 if (rtx_equal_p (XEXP (cond, 0), b))
1418 else if (rtx_equal_p (XEXP (cond, 1), b))
1423 /* Verify that C is zero. Search backward through the block for
1424 a REG_EQUAL note if necessary. */
1427 rtx insn, note = NULL;
1428 for (insn = earliest;
1429 insn != if_info->test_bb->head;
1430 insn = PREV_INSN (insn))
1432 && ((note = find_reg_note (insn, REG_EQUAL, c))
1433 || (note = find_reg_note (insn, REG_EQUIV, c))))
1439 if (GET_CODE (c) == MEM
1440 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1441 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1442 c = get_pool_constant (XEXP (c, 0));
1444 /* Work around funny ideas get_condition has wrt canonicalization.
1445 Note that these rtx constants are known to be CONST_INT, and
1446 therefore imply integer comparisons. */
1447 if (c == constm1_rtx && GET_CODE (cond) == GT)
1449 else if (c == const1_rtx && GET_CODE (cond) == LT)
1451 else if (c != CONST0_RTX (GET_MODE (b)))
1454 /* Determine what sort of operation this is. */
1455 switch (GET_CODE (cond))
1474 target = expand_simple_unop (GET_MODE (if_info->x), ABS, b, if_info->x, 0);
1476 /* ??? It's a quandry whether cmove would be better here, especially
1477 for integers. Perhaps combine will clean things up. */
1478 if (target && negate)
1479 target = expand_simple_unop (GET_MODE (target), NEG, target, if_info->x, 0);
1487 if (target != if_info->x)
1488 noce_emit_move_insn (if_info->x, target);
1493 if (seq_contains_jump (seq))
1496 emit_insns_before (seq, earliest);
1497 if_info->cond = cond;
1498 if_info->cond_earliest = earliest;
1503 /* Look for the condition for the jump first. We'd prefer to avoid
1504 get_condition if we can -- it tries to look back for the contents
1505 of an original compare. On targets that use normal integers for
1506 comparisons, e.g. alpha, this is wasteful. */
1509 noce_get_condition (jump, earliest)
1516 /* If the condition variable is a register and is MODE_INT, accept it.
1517 Otherwise, fall back on get_condition. */
1519 if (! any_condjump_p (jump))
1522 set = pc_set (jump);
1524 cond = XEXP (SET_SRC (set), 0);
1525 if (GET_CODE (XEXP (cond, 0)) == REG
1526 && GET_MODE_CLASS (GET_MODE (XEXP (cond, 0))) == MODE_INT)
1530 /* If this branches to JUMP_LABEL when the condition is false,
1531 reverse the condition. */
1532 if (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1533 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump))
1534 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
1535 GET_MODE (cond), XEXP (cond, 0),
1539 cond = get_condition (jump, earliest);
1544 /* Return true if OP is ok for if-then-else processing. */
1547 noce_operand_ok (op)
1550 /* We special-case memories, so handle any of them with
1551 no address side effects. */
1552 if (GET_CODE (op) == MEM)
1553 return ! side_effects_p (XEXP (op, 0));
1555 if (side_effects_p (op))
1558 /* ??? Unfortuantely may_trap_p can't look at flag_trapping_math, due to
1559 being linked into the genfoo programs. This is probably a mistake.
1560 With finite operands, most fp operations don't trap. */
1561 if (!flag_trapping_math && FLOAT_MODE_P (GET_MODE (op)))
1562 switch (GET_CODE (op))
1568 /* ??? This is kinda lame -- almost every target will have forced
1569 the constant into a register first. But given the expense of
1570 division, this is probably for the best. */
1571 return (CONSTANT_P (XEXP (op, 1))
1572 && XEXP (op, 1) != CONST0_RTX (GET_MODE (op))
1573 && ! may_trap_p (XEXP (op, 0)));
1576 switch (GET_RTX_CLASS (GET_CODE (op)))
1579 return ! may_trap_p (XEXP (op, 0));
1582 return ! may_trap_p (XEXP (op, 0)) && ! may_trap_p (XEXP (op, 1));
1587 return ! may_trap_p (op);
1590 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1591 without using conditional execution. Return TRUE if we were
1592 successful at converting the the block. */
1595 noce_process_if_block (test_bb, then_bb, else_bb, join_bb)
1596 basic_block test_bb; /* Basic block test is in */
1597 basic_block then_bb; /* Basic block for THEN block */
1598 basic_block else_bb; /* Basic block for ELSE block */
1599 basic_block join_bb; /* Basic block the join label is in */
1601 /* We're looking for patterns of the form
1603 (1) if (...) x = a; else x = b;
1604 (2) x = b; if (...) x = a;
1605 (3) if (...) x = a; // as if with an initial x = x.
1607 The later patterns require jumps to be more expensive.
1609 ??? For future expansion, look for multiple X in such patterns. */
1611 struct noce_if_info if_info;
1614 rtx orig_x, x, a, b;
1615 rtx jump, cond, insn;
1617 /* If this is not a standard conditional jump, we can't parse it. */
1618 jump = test_bb->end;
1619 cond = noce_get_condition (jump, &if_info.cond_earliest);
1623 /* If the conditional jump is more than just a conditional jump,
1624 then we can not do if-conversion on this block. */
1625 if (! onlyjump_p (jump))
1628 /* We must be comparing objects whose modes imply the size. */
1629 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
1632 /* Look for one of the potential sets. */
1633 insn_a = first_active_insn (then_bb);
1635 || ! last_active_insn_p (then_bb, insn_a)
1636 || (set_a = single_set (insn_a)) == NULL_RTX)
1639 x = SET_DEST (set_a);
1640 a = SET_SRC (set_a);
1642 /* Look for the other potential set. Make sure we've got equivalent
1644 /* ??? This is overconservative. Storing to two different mems is
1645 as easy as conditionally computing the address. Storing to a
1646 single mem merely requires a scratch memory to use as one of the
1647 destination addresses; often the memory immediately below the
1648 stack pointer is available for this. */
1652 insn_b = first_active_insn (else_bb);
1654 || ! last_active_insn_p (else_bb, insn_b)
1655 || (set_b = single_set (insn_b)) == NULL_RTX
1656 || ! rtx_equal_p (x, SET_DEST (set_b)))
1661 insn_b = prev_nonnote_insn (if_info.cond_earliest);
1663 || GET_CODE (insn_b) != INSN
1664 || (set_b = single_set (insn_b)) == NULL_RTX
1665 || ! rtx_equal_p (x, SET_DEST (set_b))
1666 || reg_mentioned_p (x, cond)
1667 || reg_mentioned_p (x, a)
1668 || reg_mentioned_p (x, SET_SRC (set_b)))
1669 insn_b = set_b = NULL_RTX;
1671 b = (set_b ? SET_SRC (set_b) : x);
1673 /* X may not be mentioned in the range (cond_earliest, jump]. */
1674 for (insn = jump; insn != if_info.cond_earliest; insn = PREV_INSN (insn))
1675 if (INSN_P (insn) && reg_mentioned_p (x, insn))
1678 /* A and B may not be modified in the range [cond_earliest, jump). */
1679 for (insn = if_info.cond_earliest; insn != jump; insn = NEXT_INSN (insn))
1681 && (modified_in_p (a, insn) || modified_in_p (b, insn)))
1684 /* Only operate on register destinations, and even then avoid extending
1685 the lifetime of hard registers on small register class machines. */
1687 if (GET_CODE (x) != REG
1688 || (SMALL_REGISTER_CLASSES
1689 && REGNO (x) < FIRST_PSEUDO_REGISTER))
1693 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
1694 ? XEXP (x, 0) : x));
1697 /* Don't operate on sources that may trap or are volatile. */
1698 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
1701 /* Set up the info block for our subroutines. */
1702 if_info.test_bb = test_bb;
1703 if_info.cond = cond;
1704 if_info.jump = jump;
1705 if_info.insn_a = insn_a;
1706 if_info.insn_b = insn_b;
1711 /* Try optimizations in some approximation of a useful order. */
1712 /* ??? Should first look to see if X is live incoming at all. If it
1713 isn't, we don't need anything but an unconditional set. */
1715 /* Look and see if A and B are really the same. Avoid creating silly
1716 cmove constructs that no one will fix up later. */
1717 if (rtx_equal_p (a, b))
1719 /* If we have an INSN_B, we don't have to create any new rtl. Just
1720 move the instruction that we already have. If we don't have an
1721 INSN_B, that means that A == X, and we've got a noop move. In
1722 that case don't do anything and let the code below delete INSN_A. */
1723 if (insn_b && else_bb)
1727 if (else_bb && insn_b == else_bb->end)
1728 else_bb->end = PREV_INSN (insn_b);
1729 reorder_insns (insn_b, insn_b, PREV_INSN (if_info.cond_earliest));
1731 /* If there was a REG_EQUAL note, delete it since it may have been
1732 true due to this insn being after a jump. */
1733 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
1734 remove_note (insn_b, note);
1738 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
1739 x must be executed twice. */
1740 else if (insn_b && side_effects_p (orig_x))
1747 if (noce_try_store_flag (&if_info))
1749 if (noce_try_minmax (&if_info))
1751 if (noce_try_abs (&if_info))
1753 if (HAVE_conditional_move
1754 && noce_try_cmove (&if_info))
1756 if (! HAVE_conditional_execution)
1758 if (noce_try_store_flag_constants (&if_info))
1760 if (noce_try_store_flag_inc (&if_info))
1762 if (noce_try_store_flag_mask (&if_info))
1764 if (HAVE_conditional_move
1765 && noce_try_cmove_arith (&if_info))
1772 /* The original sets may now be killed. */
1773 delete_insn (insn_a);
1775 /* Several special cases here: First, we may have reused insn_b above,
1776 in which case insn_b is now NULL. Second, we want to delete insn_b
1777 if it came from the ELSE block, because follows the now correct
1778 write that appears in the TEST block. However, if we got insn_b from
1779 the TEST block, it may in fact be loading data needed for the comparison.
1780 We'll let life_analysis remove the insn if it's really dead. */
1781 if (insn_b && else_bb)
1782 delete_insn (insn_b);
1784 /* The new insns will have been inserted before cond_earliest. We should
1785 be able to remove the jump with impunity, but the condition itself may
1786 have been modified by gcse to be shared across basic blocks. */
1789 /* If we used a temporary, fix it up now. */
1793 noce_emit_move_insn (copy_rtx (orig_x), x);
1794 insn_b = gen_sequence ();
1797 emit_insn_after (insn_b, test_bb->end);
1800 /* Merge the blocks! */
1801 merge_if_block (test_bb, then_bb, else_bb, join_bb);
1806 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
1807 straight line code. Return true if successful. */
1810 process_if_block (test_bb, then_bb, else_bb, join_bb)
1811 basic_block test_bb; /* Basic block test is in */
1812 basic_block then_bb; /* Basic block for THEN block */
1813 basic_block else_bb; /* Basic block for ELSE block */
1814 basic_block join_bb; /* Basic block the join label is in */
1816 if (! reload_completed
1817 && noce_process_if_block (test_bb, then_bb, else_bb, join_bb))
1820 if (HAVE_conditional_execution
1822 && cond_exec_process_if_block (test_bb, then_bb, else_bb, join_bb))
1828 /* Merge the blocks and mark for local life update. */
1831 merge_if_block (test_bb, then_bb, else_bb, join_bb)
1832 basic_block test_bb; /* Basic block test is in */
1833 basic_block then_bb; /* Basic block for THEN block */
1834 basic_block else_bb; /* Basic block for ELSE block */
1835 basic_block join_bb; /* Basic block the join label is in */
1837 basic_block combo_bb;
1839 /* All block merging is done into the lower block numbers. */
1843 /* First merge TEST block into THEN block. This is a no-brainer since
1844 the THEN block did not have a code label to begin with. */
1846 if (combo_bb->global_live_at_end)
1847 COPY_REG_SET (combo_bb->global_live_at_end, then_bb->global_live_at_end);
1848 merge_blocks_nomove (combo_bb, then_bb);
1849 num_removed_blocks++;
1851 /* The ELSE block, if it existed, had a label. That label count
1852 will almost always be zero, but odd things can happen when labels
1853 get their addresses taken. */
1856 merge_blocks_nomove (combo_bb, else_bb);
1857 num_removed_blocks++;
1860 /* If there was no join block reported, that means it was not adjacent
1861 to the others, and so we cannot merge them. */
1865 /* The outgoing edge for the current COMBO block should already
1866 be correct. Verify this. */
1867 if (combo_bb->succ == NULL_EDGE)
1870 /* There should still be a branch at the end of the THEN or ELSE
1871 blocks taking us to our final destination. */
1872 if (GET_CODE (combo_bb->end) != JUMP_INSN)
1876 /* The JOIN block may have had quite a number of other predecessors too.
1877 Since we've already merged the TEST, THEN and ELSE blocks, we should
1878 have only one remaining edge from our if-then-else diamond. If there
1879 is more than one remaining edge, it must come from elsewhere. There
1880 may be zero incoming edges if the THEN block didn't actually join
1881 back up (as with a call to abort). */
1882 else if ((join_bb->pred == NULL
1883 || join_bb->pred->pred_next == NULL)
1884 && join_bb != EXIT_BLOCK_PTR)
1886 /* We can merge the JOIN. */
1887 if (combo_bb->global_live_at_end)
1888 COPY_REG_SET (combo_bb->global_live_at_end,
1889 join_bb->global_live_at_end);
1890 merge_blocks_nomove (combo_bb, join_bb);
1891 num_removed_blocks++;
1895 /* We cannot merge the JOIN. */
1897 /* The outgoing edge for the current COMBO block should already
1898 be correct. Verify this. */
1899 if (combo_bb->succ->succ_next != NULL_EDGE
1900 || combo_bb->succ->dest != join_bb)
1903 /* Remove the jump and cruft from the end of the COMBO block. */
1904 if (join_bb != EXIT_BLOCK_PTR)
1905 tidy_fallthru_edge (combo_bb->succ, combo_bb, join_bb);
1908 num_updated_if_blocks++;
1911 /* Find a block ending in a simple IF condition. Return TRUE if
1912 we were able to transform it in some way. */
1915 find_if_header (test_bb)
1916 basic_block test_bb;
1921 /* The kind of block we're looking for has exactly two successors. */
1922 if ((then_edge = test_bb->succ) == NULL_EDGE
1923 || (else_edge = then_edge->succ_next) == NULL_EDGE
1924 || else_edge->succ_next != NULL_EDGE)
1927 /* Neither edge should be abnormal. */
1928 if ((then_edge->flags & EDGE_COMPLEX)
1929 || (else_edge->flags & EDGE_COMPLEX))
1932 /* The THEN edge is canonically the one that falls through. */
1933 if (then_edge->flags & EDGE_FALLTHRU)
1935 else if (else_edge->flags & EDGE_FALLTHRU)
1938 else_edge = then_edge;
1942 /* Otherwise this must be a multiway branch of some sort. */
1945 if (find_if_block (test_bb, then_edge, else_edge))
1947 if (HAVE_trap && HAVE_conditional_trap
1948 && find_cond_trap (test_bb, then_edge, else_edge))
1951 && (! HAVE_conditional_execution || reload_completed))
1953 if (find_if_case_1 (test_bb, then_edge, else_edge))
1955 if (find_if_case_2 (test_bb, then_edge, else_edge))
1963 fprintf (rtl_dump_file, "Conversion succeeded.\n");
1967 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
1968 block. If so, we'll try to convert the insns to not require the branch.
1969 Return TRUE if we were successful at converting the the block. */
1972 find_if_block (test_bb, then_edge, else_edge)
1973 basic_block test_bb;
1974 edge then_edge, else_edge;
1976 basic_block then_bb = then_edge->dest;
1977 basic_block else_bb = else_edge->dest;
1978 basic_block join_bb = NULL_BLOCK;
1979 edge then_succ = then_bb->succ;
1980 edge else_succ = else_bb->succ;
1983 /* The THEN block of an IF-THEN combo must have exactly one predecessor. */
1984 if (then_bb->pred->pred_next != NULL_EDGE)
1987 /* The THEN block of an IF-THEN combo must have zero or one successors. */
1988 if (then_succ != NULL_EDGE
1989 && (then_succ->succ_next != NULL_EDGE
1990 || (then_succ->flags & EDGE_COMPLEX)))
1993 /* If the THEN block has no successors, conditional execution can still
1994 make a conditional call. Don't do this unless the ELSE block has
1995 only one incoming edge -- the CFG manipulation is too ugly otherwise.
1996 Check for the last insn of the THEN block being an indirect jump, which
1997 is listed as not having any successors, but confuses the rest of the CE
1998 code processing. XXX we should fix this in the future. */
1999 if (then_succ == NULL)
2001 if (else_bb->pred->pred_next == NULL_EDGE)
2003 rtx last_insn = then_bb->end;
2006 && GET_CODE (last_insn) == NOTE
2007 && last_insn != then_bb->head)
2008 last_insn = PREV_INSN (last_insn);
2011 && GET_CODE (last_insn) == JUMP_INSN
2012 && ! simplejump_p (last_insn))
2016 else_bb = NULL_BLOCK;
2022 /* If the THEN block's successor is the other edge out of the TEST block,
2023 then we have an IF-THEN combo without an ELSE. */
2024 else if (then_succ->dest == else_bb)
2027 else_bb = NULL_BLOCK;
2030 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2031 has exactly one predecessor and one successor, and the outgoing edge
2032 is not complex, then we have an IF-THEN-ELSE combo. */
2033 else if (else_succ != NULL_EDGE
2034 && then_succ->dest == else_succ->dest
2035 && else_bb->pred->pred_next == NULL_EDGE
2036 && else_succ->succ_next == NULL_EDGE
2037 && ! (else_succ->flags & EDGE_COMPLEX))
2038 join_bb = else_succ->dest;
2040 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2044 num_possible_if_blocks++;
2049 fprintf (rtl_dump_file,
2050 "\nIF-THEN-ELSE block found, start %d, then %d, else %d, join %d\n",
2051 test_bb->index, then_bb->index, else_bb->index,
2054 fprintf (rtl_dump_file,
2055 "\nIF-THEN block found, start %d, then %d, join %d\n",
2056 test_bb->index, then_bb->index, join_bb->index);
2059 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we
2060 get the first condition for free, since we've already asserted that
2061 there's a fallthru edge from IF to THEN. */
2062 /* ??? As an enhancement, move the ELSE block. Have to deal with
2063 BLOCK notes, if by no other means than aborting the merge if they
2064 exist. Sticky enough I don't want to think about it now. */
2065 next_index = then_bb->index;
2066 if (else_bb && ++next_index != else_bb->index)
2068 if (++next_index != join_bb->index && join_bb->index != EXIT_BLOCK)
2076 /* Do the real work. */
2077 return process_if_block (test_bb, then_bb, else_bb, join_bb);
2080 /* Convert a branch over a trap, or a branch to a trap,
2081 into a conditional trap. */
2084 find_cond_trap (test_bb, then_edge, else_edge)
2085 basic_block test_bb;
2086 edge then_edge, else_edge;
2088 basic_block then_bb, else_bb, join_bb, trap_bb;
2089 rtx trap, jump, cond, cond_earliest, seq;
2092 then_bb = then_edge->dest;
2093 else_bb = else_edge->dest;
2096 /* Locate the block with the trap instruction. */
2097 /* ??? While we look for no successors, we really ought to allow
2098 EH successors. Need to fix merge_if_block for that to work. */
2099 /* ??? We can't currently handle merging the blocks if they are not
2100 already adjacent. Prevent losage in merge_if_block by detecting
2102 if (then_bb->succ == NULL)
2105 if (else_bb->index != then_bb->index + 1)
2110 else if (else_bb->succ == NULL)
2113 if (else_bb->index != then_bb->index + 1)
2115 else if (then_bb->succ
2116 && ! then_bb->succ->succ_next
2117 && ! (then_bb->succ->flags & EDGE_COMPLEX)
2118 && then_bb->succ->dest->index == else_bb->index + 1)
2119 join_bb = then_bb->succ->dest;
2124 /* Don't confuse a conditional return with something we want to
2126 if (trap_bb == EXIT_BLOCK_PTR)
2129 /* The only instruction in the THEN block must be the trap. */
2130 trap = first_active_insn (trap_bb);
2131 if (! (trap == trap_bb->end
2132 && GET_CODE (PATTERN (trap)) == TRAP_IF
2133 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
2138 if (trap_bb == then_bb)
2139 fprintf (rtl_dump_file,
2140 "\nTRAP-IF block found, start %d, trap %d",
2141 test_bb->index, then_bb->index);
2143 fprintf (rtl_dump_file,
2144 "\nTRAP-IF block found, start %d, then %d, trap %d",
2145 test_bb->index, then_bb->index, trap_bb->index);
2147 fprintf (rtl_dump_file, ", join %d\n", join_bb->index);
2149 fputc ('\n', rtl_dump_file);
2152 /* If this is not a standard conditional jump, we can't parse it. */
2153 jump = test_bb->end;
2154 cond = noce_get_condition (jump, &cond_earliest);
2158 /* If the conditional jump is more than just a conditional jump,
2159 then we can not do if-conversion on this block. */
2160 if (! onlyjump_p (jump))
2163 /* We must be comparing objects whose modes imply the size. */
2164 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2167 /* Reverse the comparison code, if necessary. */
2168 code = GET_CODE (cond);
2169 if (then_bb == trap_bb)
2171 code = reversed_comparison_code (cond, jump);
2172 if (code == UNKNOWN)
2176 /* Attempt to generate the conditional trap. */
2177 seq = gen_cond_trap (code, XEXP (cond, 0), XEXP (cond, 1),
2178 TRAP_CODE (PATTERN (trap)));
2182 /* Emit the new insns before cond_earliest; delete the old jump
2185 emit_insn_before (seq, cond_earliest);
2191 /* Merge the blocks! */
2192 if (trap_bb != then_bb && ! else_bb)
2194 flow_delete_block (trap_bb);
2195 num_removed_blocks++;
2197 merge_if_block (test_bb, then_bb, else_bb, join_bb);
2202 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2203 transformable, but not necessarily the other. There need be no
2206 Return TRUE if we were successful at converting the the block.
2208 Cases we'd like to look at:
2211 if (test) goto over; // x not live
2219 if (! test) goto label;
2222 if (test) goto E; // x not live
2236 (3) // This one's really only interesting for targets that can do
2237 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2238 // it results in multiple branches on a cache line, which often
2239 // does not sit well with predictors.
2241 if (test1) goto E; // predicted not taken
2257 (A) Don't do (2) if the branch is predicted against the block we're
2258 eliminating. Do it anyway if we can eliminate a branch; this requires
2259 that the sole successor of the eliminated block postdominate the other
2262 (B) With CE, on (3) we can steal from both sides of the if, creating
2271 Again, this is most useful if J postdominates.
2273 (C) CE substitutes for helpful life information.
2275 (D) These heuristics need a lot of work. */
2277 /* Tests for case 1 above. */
2280 find_if_case_1 (test_bb, then_edge, else_edge)
2281 basic_block test_bb;
2282 edge then_edge, else_edge;
2284 basic_block then_bb = then_edge->dest;
2285 basic_block else_bb = else_edge->dest, new_bb;
2286 edge then_succ = then_bb->succ;
2288 /* THEN has one successor. */
2289 if (!then_succ || then_succ->succ_next != NULL)
2292 /* THEN does not fall through, but is not strange either. */
2293 if (then_succ->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
2296 /* THEN has one predecessor. */
2297 if (then_bb->pred->pred_next != NULL)
2300 /* THEN must do something. */
2301 if (forwarder_block_p (then_bb))
2304 num_possible_if_blocks++;
2306 fprintf (rtl_dump_file,
2307 "\nIF-CASE-1 found, start %d, then %d\n",
2308 test_bb->index, then_bb->index);
2310 /* THEN is small. */
2311 if (count_bb_insns (then_bb) > BRANCH_COST)
2314 /* Registers set are dead, or are predicable. */
2315 if (! dead_or_predicable (test_bb, then_bb, else_bb,
2316 then_bb->succ->dest, 1))
2319 /* Conversion went ok, including moving the insns and fixing up the
2320 jump. Adjust the CFG to match. */
2322 bitmap_operation (test_bb->global_live_at_end,
2323 else_bb->global_live_at_start,
2324 then_bb->global_live_at_end, BITMAP_IOR);
2326 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb), else_bb);
2327 /* Make rest of code believe that the newly created block is the THEN_BB
2328 block we are going to remove. */
2330 new_bb->aux = then_bb->aux;
2331 flow_delete_block (then_bb);
2332 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2335 num_removed_blocks++;
2336 num_updated_if_blocks++;
2341 /* Test for case 2 above. */
2344 find_if_case_2 (test_bb, then_edge, else_edge)
2345 basic_block test_bb;
2346 edge then_edge, else_edge;
2348 basic_block then_bb = then_edge->dest;
2349 basic_block else_bb = else_edge->dest;
2350 edge else_succ = else_bb->succ;
2353 /* ELSE has one successor. */
2354 if (!else_succ || else_succ->succ_next != NULL)
2357 /* ELSE outgoing edge is not complex. */
2358 if (else_succ->flags & EDGE_COMPLEX)
2361 /* ELSE has one predecessor. */
2362 if (else_bb->pred->pred_next != NULL)
2365 /* THEN is not EXIT. */
2366 if (then_bb->index < 0)
2369 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2370 note = find_reg_note (test_bb->end, REG_BR_PROB, NULL_RTX);
2371 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
2373 else if (else_succ->dest->index < 0
2374 || TEST_BIT (post_dominators[ORIG_INDEX (then_bb)],
2375 ORIG_INDEX (else_succ->dest)))
2380 num_possible_if_blocks++;
2382 fprintf (rtl_dump_file,
2383 "\nIF-CASE-2 found, start %d, else %d\n",
2384 test_bb->index, else_bb->index);
2386 /* ELSE is small. */
2387 if (count_bb_insns (then_bb) > BRANCH_COST)
2390 /* Registers set are dead, or are predicable. */
2391 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
2394 /* Conversion went ok, including moving the insns and fixing up the
2395 jump. Adjust the CFG to match. */
2397 bitmap_operation (test_bb->global_live_at_end,
2398 then_bb->global_live_at_start,
2399 else_bb->global_live_at_end, BITMAP_IOR);
2401 flow_delete_block (else_bb);
2403 num_removed_blocks++;
2404 num_updated_if_blocks++;
2406 /* ??? We may now fallthru from one of THEN's successors into a join
2407 block. Rerun cleanup_cfg? Examine things manually? Wait? */
2412 /* A subroutine of dead_or_predicable called through for_each_rtx.
2413 Return 1 if a memory is found. */
2416 find_memory (px, data)
2418 void *data ATTRIBUTE_UNUSED;
2420 return GET_CODE (*px) == MEM;
2423 /* Used by the code above to perform the actual rtl transformations.
2424 Return TRUE if successful.
2426 TEST_BB is the block containing the conditional branch. MERGE_BB
2427 is the block containing the code to manipulate. NEW_DEST is the
2428 label TEST_BB should be branching to after the conversion.
2429 REVERSEP is true if the sense of the branch should be reversed. */
2432 dead_or_predicable (test_bb, merge_bb, other_bb, new_dest, reversep)
2433 basic_block test_bb, merge_bb, other_bb;
2434 basic_block new_dest;
2437 rtx head, end, jump, earliest, old_dest, new_label;
2439 jump = test_bb->end;
2441 /* Find the extent of the real code in the merge block. */
2442 head = merge_bb->head;
2443 end = merge_bb->end;
2445 if (GET_CODE (head) == CODE_LABEL)
2446 head = NEXT_INSN (head);
2447 if (GET_CODE (head) == NOTE)
2451 head = end = NULL_RTX;
2454 head = NEXT_INSN (head);
2457 if (GET_CODE (end) == JUMP_INSN)
2461 head = end = NULL_RTX;
2464 end = PREV_INSN (end);
2467 /* Disable handling dead code by conditional execution if the machine needs
2468 to do anything funny with the tests, etc. */
2469 #ifndef IFCVT_MODIFY_TESTS
2470 if (HAVE_conditional_execution)
2472 /* In the conditional execution case, we have things easy. We know
2473 the condition is reversable. We don't have to check life info,
2474 becase we're going to conditionally execute the code anyway.
2475 All that's left is making sure the insns involved can actually
2480 cond = cond_exec_get_condition (jump);
2484 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
2486 prob_val = XEXP (prob_val, 0);
2490 enum rtx_code rev = reversed_comparison_code (cond, jump);
2493 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
2496 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
2499 if (! cond_exec_process_insns (head, end, cond, prob_val, 0))
2507 /* In the non-conditional execution case, we have to verify that there
2508 are no trapping operations, no calls, no references to memory, and
2509 that any registers modified are dead at the branch site. */
2511 rtx insn, cond, prev;
2512 regset_head merge_set_head, tmp_head, test_live_head, test_set_head;
2513 regset merge_set, tmp, test_live, test_set;
2514 struct propagate_block_info *pbi;
2517 /* Check for no calls or trapping operations. */
2518 for (insn = head; ; insn = NEXT_INSN (insn))
2520 if (GET_CODE (insn) == CALL_INSN)
2524 if (may_trap_p (PATTERN (insn)))
2527 /* ??? Even non-trapping memories such as stack frame
2528 references must be avoided. For stores, we collect
2529 no lifetime info; for reads, we'd have to assert
2530 true_dependence false against every store in the
2532 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
2539 if (! any_condjump_p (jump))
2542 /* Find the extent of the conditional. */
2543 cond = noce_get_condition (jump, &earliest);
2548 MERGE_SET = set of registers set in MERGE_BB
2549 TEST_LIVE = set of registers live at EARLIEST
2550 TEST_SET = set of registers set between EARLIEST and the
2551 end of the block. */
2553 tmp = INITIALIZE_REG_SET (tmp_head);
2554 merge_set = INITIALIZE_REG_SET (merge_set_head);
2555 test_live = INITIALIZE_REG_SET (test_live_head);
2556 test_set = INITIALIZE_REG_SET (test_set_head);
2558 /* ??? bb->local_set is only valid during calculate_global_regs_live,
2559 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
2560 since we've already asserted that MERGE_BB is small. */
2561 propagate_block (merge_bb, tmp, merge_set, merge_set, 0);
2563 /* For small register class machines, don't lengthen lifetimes of
2564 hard registers before reload. */
2565 if (SMALL_REGISTER_CLASSES && ! reload_completed)
2567 EXECUTE_IF_SET_IN_BITMAP
2570 if (i < FIRST_PSEUDO_REGISTER
2572 && ! global_regs[i])
2577 /* For TEST, we're interested in a range of insns, not a whole block.
2578 Moreover, we're interested in the insns live from OTHER_BB. */
2580 COPY_REG_SET (test_live, other_bb->global_live_at_start);
2581 pbi = init_propagate_block_info (test_bb, test_live, test_set, test_set,
2584 for (insn = jump; ; insn = prev)
2586 prev = propagate_one_insn (pbi, insn);
2587 if (insn == earliest)
2591 free_propagate_block_info (pbi);
2593 /* We can perform the transformation if
2594 MERGE_SET & (TEST_SET | TEST_LIVE)
2596 TEST_SET & merge_bb->global_live_at_start
2599 bitmap_operation (tmp, test_set, test_live, BITMAP_IOR);
2600 bitmap_operation (tmp, tmp, merge_set, BITMAP_AND);
2601 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
2603 bitmap_operation (tmp, test_set, merge_bb->global_live_at_start,
2605 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
2608 FREE_REG_SET (merge_set);
2609 FREE_REG_SET (test_live);
2610 FREE_REG_SET (test_set);
2617 /* We don't want to use normal invert_jump or redirect_jump because
2618 we don't want to delete_insn called. Also, we want to do our own
2619 change group management. */
2621 old_dest = JUMP_LABEL (jump);
2622 if (other_bb != new_dest)
2624 new_label = block_label (new_dest);
2626 ? ! invert_jump_1 (jump, new_label)
2627 : ! redirect_jump_1 (jump, new_label))
2631 if (! apply_change_group ())
2634 if (other_bb != new_dest)
2637 LABEL_NUSES (old_dest) -= 1;
2639 LABEL_NUSES (new_label) += 1;
2640 JUMP_LABEL (jump) = new_label;
2642 invert_br_probabilities (jump);
2644 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
2647 gcov_type count, probability;
2648 count = BRANCH_EDGE (test_bb)->count;
2649 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
2650 FALLTHRU_EDGE (test_bb)->count = count;
2651 probability = BRANCH_EDGE (test_bb)->probability;
2652 BRANCH_EDGE (test_bb)->probability
2653 = FALLTHRU_EDGE (test_bb)->probability;
2654 FALLTHRU_EDGE (test_bb)->probability = probability;
2655 update_br_prob_note (test_bb);
2659 /* Move the insns out of MERGE_BB to before the branch. */
2662 if (end == merge_bb->end)
2663 merge_bb->end = PREV_INSN (head);
2665 if (squeeze_notes (&head, &end))
2668 reorder_insns (head, end, PREV_INSN (earliest));
2671 /* Remove the jump and edge if we can. */
2672 if (other_bb == new_dest)
2675 remove_edge (BRANCH_EDGE (test_bb));
2676 /* ??? Can't merge blocks here, as then_bb is still in use.
2677 At minimum, the merge will get done just before bb-reorder. */
2687 /* Main entry point for all if-conversion. */
2690 if_convert (x_life_data_ok)
2695 num_possible_if_blocks = 0;
2696 num_updated_if_blocks = 0;
2697 num_removed_blocks = 0;
2698 life_data_ok = (x_life_data_ok != 0);
2700 /* Free up basic_block_for_insn so that we don't have to keep it
2701 up to date, either here or in merge_blocks_nomove. */
2702 free_basic_block_vars (1);
2704 /* Compute postdominators if we think we'll use them. */
2705 post_dominators = NULL;
2706 if (HAVE_conditional_execution || life_data_ok)
2708 post_dominators = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
2709 calculate_dominance_info (NULL, post_dominators, CDI_POST_DOMINATORS);
2714 /* Record initial block numbers. */
2715 for (block_num = 0; block_num < n_basic_blocks; block_num++)
2716 SET_ORIG_INDEX (BASIC_BLOCK (block_num), block_num);
2718 /* Go through each of the basic blocks looking for things to convert. */
2719 for (block_num = 0; block_num < n_basic_blocks; )
2721 basic_block bb = BASIC_BLOCK (block_num);
2722 if (find_if_header (bb))
2723 block_num = bb->index;
2728 if (post_dominators)
2729 sbitmap_vector_free (post_dominators);
2732 fflush (rtl_dump_file);
2734 /* Rebuild life info for basic blocks that require it. */
2735 if (num_removed_blocks && life_data_ok)
2737 /* If we allocated new pseudos, we must resize the array for sched1. */
2738 if (max_regno < max_reg_num ())
2740 max_regno = max_reg_num ();
2741 allocate_reg_info (max_regno, FALSE, FALSE);
2743 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES,
2744 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2745 | PROP_KILL_DEAD_CODE);
2747 clear_aux_for_blocks ();
2749 /* Write the final stats. */
2750 if (rtl_dump_file && num_possible_if_blocks > 0)
2752 fprintf (rtl_dump_file,
2753 "\n%d possible IF blocks searched.\n",
2754 num_possible_if_blocks);
2755 fprintf (rtl_dump_file,
2756 "%d IF blocks converted.\n",
2757 num_updated_if_blocks);
2758 fprintf (rtl_dump_file,
2759 "%d basic blocks deleted.\n\n\n",
2760 num_removed_blocks);
2763 #ifdef ENABLE_CHECKING
2764 verify_flow_info ();