1 /* If-conversion support.
2 Copyright (C) 2000, 2001, 2002 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"
31 #include "hard-reg-set.h"
32 #include "basic-block.h"
40 #ifndef HAVE_conditional_execution
41 #define HAVE_conditional_execution 0
43 #ifndef HAVE_conditional_move
44 #define HAVE_conditional_move 0
55 #ifndef HAVE_conditional_trap
56 #define HAVE_conditional_trap 0
59 #ifndef MAX_CONDITIONAL_EXECUTE
60 #define MAX_CONDITIONAL_EXECUTE (BRANCH_COST + 1)
63 #define NULL_EDGE ((struct edge_def *)NULL)
64 #define NULL_BLOCK ((struct basic_block_def *)NULL)
66 /* # of IF-THEN or IF-THEN-ELSE blocks we looked at */
67 static int num_possible_if_blocks;
69 /* # of IF-THEN or IF-THEN-ELSE blocks were converted to conditional
71 static int num_updated_if_blocks;
73 /* # of basic blocks that were removed. */
74 static int num_removed_blocks;
76 /* True if life data ok at present. */
77 static bool life_data_ok;
79 /* The post-dominator relation on the original block numbers. */
80 static sbitmap *post_dominators;
82 /* Forward references. */
83 static int count_bb_insns PARAMS ((basic_block));
84 static rtx first_active_insn PARAMS ((basic_block));
85 static int last_active_insn_p PARAMS ((basic_block, rtx));
86 static int seq_contains_jump PARAMS ((rtx));
88 static int cond_exec_process_insns PARAMS ((rtx, rtx, rtx, rtx, int));
89 static rtx cond_exec_get_condition PARAMS ((rtx));
90 static int cond_exec_process_if_block PARAMS ((basic_block, basic_block,
91 basic_block, basic_block));
93 static rtx noce_get_condition PARAMS ((rtx, rtx *));
94 static int noce_operand_ok PARAMS ((rtx));
95 static int noce_process_if_block PARAMS ((basic_block, basic_block,
96 basic_block, basic_block));
98 static int process_if_block PARAMS ((basic_block, basic_block,
99 basic_block, basic_block));
100 static void merge_if_block PARAMS ((basic_block, basic_block,
101 basic_block, basic_block));
103 static int find_if_header PARAMS ((basic_block));
104 static int find_if_block PARAMS ((basic_block, edge, edge));
105 static int find_if_case_1 PARAMS ((basic_block, edge, edge));
106 static int find_if_case_2 PARAMS ((basic_block, edge, edge));
107 static int find_cond_trap PARAMS ((basic_block, edge, edge));
108 static rtx block_has_only_trap PARAMS ((basic_block));
109 static int find_memory PARAMS ((rtx *, void *));
110 static int dead_or_predicable PARAMS ((basic_block, basic_block,
111 basic_block, basic_block, int));
112 static void noce_emit_move_insn PARAMS ((rtx, rtx));
114 /* Abuse the basic_block AUX field to store the original block index,
115 as well as a flag indicating that the block should be rescaned for
118 #define SET_ORIG_INDEX(BB,I) ((BB)->aux = (void *)((size_t)(I)))
119 #define ORIG_INDEX(BB) ((size_t)(BB)->aux)
122 /* Count the number of non-jump active insns in BB. */
133 if (GET_CODE (insn) == CALL_INSN || GET_CODE (insn) == INSN)
138 insn = NEXT_INSN (insn);
144 /* Return the first non-jump active insn in the basic block. */
147 first_active_insn (bb)
152 if (GET_CODE (insn) == CODE_LABEL)
156 insn = NEXT_INSN (insn);
159 while (GET_CODE (insn) == NOTE)
163 insn = NEXT_INSN (insn);
166 if (GET_CODE (insn) == JUMP_INSN)
172 /* Return true if INSN is the last active non-jump insn in BB. */
175 last_active_insn_p (bb, insn)
183 insn = NEXT_INSN (insn);
185 while (GET_CODE (insn) == NOTE);
187 return GET_CODE (insn) == JUMP_INSN;
190 /* It is possible, especially when having dealt with multi-word
191 arithmetic, for the expanders to have emitted jumps. Search
192 through the sequence and return TRUE if a jump exists so that
193 we can abort the conversion. */
196 seq_contains_jump (insn)
201 if (GET_CODE (insn) == JUMP_INSN)
203 insn = NEXT_INSN (insn);
208 /* Go through a bunch of insns, converting them to conditional
209 execution format if possible. Return TRUE if all of the non-note
210 insns were processed. */
213 cond_exec_process_insns (start, end, test, prob_val, mod_ok)
214 rtx start; /* first insn to look at */
215 rtx end; /* last insn to look at */
216 rtx test; /* conditional execution test */
217 rtx prob_val; /* probability of branch taken. */
218 int mod_ok; /* true if modifications ok last insn. */
220 int must_be_last = FALSE;
224 for (insn = start; ; insn = NEXT_INSN (insn))
226 if (GET_CODE (insn) == NOTE)
229 if (GET_CODE (insn) != INSN && GET_CODE (insn) != CALL_INSN)
232 /* Remove USE insns that get in the way. */
233 if (reload_completed && GET_CODE (PATTERN (insn)) == USE)
235 /* ??? Ug. Actually unlinking the thing is problematic,
236 given what we'd have to coordinate with our callers. */
237 PUT_CODE (insn, NOTE);
238 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
239 NOTE_SOURCE_FILE (insn) = 0;
243 /* Last insn wasn't last? */
247 if (modified_in_p (test, insn))
254 /* Now build the conditional form of the instruction. */
255 pattern = PATTERN (insn);
257 /* If the machine needs to modify the insn being conditionally executed,
258 say for example to force a constant integer operand into a temp
259 register, do so here. */
260 #ifdef IFCVT_MODIFY_INSN
261 IFCVT_MODIFY_INSN (pattern, insn);
266 validate_change (insn, &PATTERN (insn),
267 gen_rtx_COND_EXEC (VOIDmode, copy_rtx (test),
270 if (GET_CODE (insn) == CALL_INSN && prob_val)
271 validate_change (insn, ®_NOTES (insn),
272 alloc_EXPR_LIST (REG_BR_PROB, prob_val,
273 REG_NOTES (insn)), 1);
283 /* Return the condition for a jump. Do not do any special processing. */
286 cond_exec_get_condition (jump)
291 if (any_condjump_p (jump))
292 test_if = SET_SRC (pc_set (jump));
295 cond = XEXP (test_if, 0);
297 /* If this branches to JUMP_LABEL when the condition is false,
298 reverse the condition. */
299 if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF
300 && XEXP (XEXP (test_if, 2), 0) == JUMP_LABEL (jump))
302 enum rtx_code rev = reversed_comparison_code (cond, jump);
306 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
313 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
314 to conditional execution. Return TRUE if we were successful at
315 converting the the block. */
318 cond_exec_process_if_block (test_bb, then_bb, else_bb, join_bb)
319 basic_block test_bb; /* Basic block test is in */
320 basic_block then_bb; /* Basic block for THEN block */
321 basic_block else_bb; /* Basic block for ELSE block */
322 basic_block join_bb; /* Basic block the join label is in */
324 rtx test_expr; /* expression in IF_THEN_ELSE that is tested */
325 rtx then_start; /* first insn in THEN block */
326 rtx then_end; /* last insn + 1 in THEN block */
327 rtx else_start = NULL_RTX; /* first insn in ELSE block or NULL */
328 rtx else_end = NULL_RTX; /* last insn + 1 in ELSE block */
329 int max; /* max # of insns to convert. */
330 int then_mod_ok; /* whether conditional mods are ok in THEN */
331 rtx true_expr; /* test for else block insns */
332 rtx false_expr; /* test for then block insns */
333 rtx true_prob_val; /* probability of else block */
334 rtx false_prob_val; /* probability of then block */
336 enum rtx_code false_code;
338 /* Find the conditional jump to the ELSE or JOIN part, and isolate
340 test_expr = cond_exec_get_condition (test_bb->end);
344 /* If the conditional jump is more than just a conditional jump,
345 then we can not do conditional execution conversion on this block. */
346 if (!onlyjump_p (test_bb->end))
349 /* Collect the bounds of where we're to search. */
351 then_start = then_bb->head;
352 then_end = then_bb->end;
354 /* Skip a label heading THEN block. */
355 if (GET_CODE (then_start) == CODE_LABEL)
356 then_start = NEXT_INSN (then_start);
358 /* Skip a (use (const_int 0)) or branch as the final insn. */
359 if (GET_CODE (then_end) == INSN
360 && GET_CODE (PATTERN (then_end)) == USE
361 && GET_CODE (XEXP (PATTERN (then_end), 0)) == CONST_INT)
362 then_end = PREV_INSN (then_end);
363 else if (GET_CODE (then_end) == JUMP_INSN)
364 then_end = PREV_INSN (then_end);
368 /* Skip the ELSE block's label. */
369 else_start = NEXT_INSN (else_bb->head);
370 else_end = else_bb->end;
372 /* Skip a (use (const_int 0)) or branch as the final insn. */
373 if (GET_CODE (else_end) == INSN
374 && GET_CODE (PATTERN (else_end)) == USE
375 && GET_CODE (XEXP (PATTERN (else_end), 0)) == CONST_INT)
376 else_end = PREV_INSN (else_end);
377 else if (GET_CODE (else_end) == JUMP_INSN)
378 else_end = PREV_INSN (else_end);
381 /* How many instructions should we convert in total? */
385 max = 2 * MAX_CONDITIONAL_EXECUTE;
386 n_insns = count_bb_insns (else_bb);
389 max = MAX_CONDITIONAL_EXECUTE;
390 n_insns += count_bb_insns (then_bb);
394 /* Map test_expr/test_jump into the appropriate MD tests to use on
395 the conditionally executed code. */
397 true_expr = test_expr;
399 false_code = reversed_comparison_code (true_expr, test_bb->end);
400 if (false_code != UNKNOWN)
401 false_expr = gen_rtx_fmt_ee (false_code, GET_MODE (true_expr),
402 XEXP (true_expr, 0), XEXP (true_expr, 1));
404 false_expr = NULL_RTX;
406 #ifdef IFCVT_MODIFY_TESTS
407 /* If the machine description needs to modify the tests, such as setting a
408 conditional execution register from a comparison, it can do so here. */
409 IFCVT_MODIFY_TESTS (true_expr, false_expr, test_bb, then_bb, else_bb,
412 /* See if the conversion failed */
413 if (!true_expr || !false_expr)
417 true_prob_val = find_reg_note (test_bb->end, REG_BR_PROB, NULL_RTX);
420 true_prob_val = XEXP (true_prob_val, 0);
421 false_prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (true_prob_val));
424 false_prob_val = NULL_RTX;
426 /* For IF-THEN-ELSE blocks, we don't allow modifications of the test
427 on then THEN block. */
428 then_mod_ok = (else_bb == NULL_BLOCK);
430 /* Go through the THEN and ELSE blocks converting the insns if possible
431 to conditional execution. */
435 || ! cond_exec_process_insns (then_start, then_end, false_expr,
436 false_prob_val, then_mod_ok)))
440 && ! cond_exec_process_insns (else_start, else_end,
441 true_expr, true_prob_val, TRUE))
444 if (! apply_change_group ())
447 #ifdef IFCVT_MODIFY_FINAL
448 /* Do any machine dependent final modifications */
449 IFCVT_MODIFY_FINAL (test_bb, then_bb, else_bb, join_bb);
452 /* Conversion succeeded. */
454 fprintf (rtl_dump_file, "%d insn%s converted to conditional execution.\n",
455 n_insns, (n_insns == 1) ? " was" : "s were");
457 /* Merge the blocks! */
458 merge_if_block (test_bb, then_bb, else_bb, join_bb);
462 #ifdef IFCVT_MODIFY_CANCEL
463 /* Cancel any machine dependent changes. */
464 IFCVT_MODIFY_CANCEL (test_bb, then_bb, else_bb, join_bb);
471 /* Used by noce_process_if_block to communicate with its subroutines.
473 The subroutines know that A and B may be evaluated freely. They
474 know that X is a register. They should insert new instructions
475 before cond_earliest. */
482 rtx jump, cond, cond_earliest;
485 static rtx noce_emit_store_flag PARAMS ((struct noce_if_info *,
487 static int noce_try_store_flag PARAMS ((struct noce_if_info *));
488 static int noce_try_store_flag_inc PARAMS ((struct noce_if_info *));
489 static int noce_try_store_flag_constants PARAMS ((struct noce_if_info *));
490 static int noce_try_store_flag_mask PARAMS ((struct noce_if_info *));
491 static rtx noce_emit_cmove PARAMS ((struct noce_if_info *,
492 rtx, enum rtx_code, rtx,
494 static int noce_try_cmove PARAMS ((struct noce_if_info *));
495 static int noce_try_cmove_arith PARAMS ((struct noce_if_info *));
496 static rtx noce_get_alt_condition PARAMS ((struct noce_if_info *,
498 static int noce_try_minmax PARAMS ((struct noce_if_info *));
499 static int noce_try_abs PARAMS ((struct noce_if_info *));
501 /* Helper function for noce_try_store_flag*. */
504 noce_emit_store_flag (if_info, x, reversep, normalize)
505 struct noce_if_info *if_info;
507 int reversep, normalize;
509 rtx cond = if_info->cond;
513 cond_complex = (! general_operand (XEXP (cond, 0), VOIDmode)
514 || ! general_operand (XEXP (cond, 1), VOIDmode));
516 /* If earliest == jump, or when the condition is complex, try to
517 build the store_flag insn directly. */
520 cond = XEXP (SET_SRC (pc_set (if_info->jump)), 0);
523 code = reversed_comparison_code (cond, if_info->jump);
525 code = GET_CODE (cond);
527 if ((if_info->cond_earliest == if_info->jump || cond_complex)
528 && (normalize == 0 || STORE_FLAG_VALUE == normalize))
532 tmp = gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (cond, 0),
534 tmp = gen_rtx_SET (VOIDmode, x, tmp);
537 tmp = emit_insn (tmp);
539 if (recog_memoized (tmp) >= 0)
545 if_info->cond_earliest = if_info->jump;
553 /* Don't even try if the comparison operands are weird. */
557 return emit_store_flag (x, code, XEXP (cond, 0),
558 XEXP (cond, 1), VOIDmode,
559 (code == LTU || code == LEU
560 || code == GEU || code == GTU), normalize);
563 /* Emit instruction to move an rtx into STRICT_LOW_PART. */
565 noce_emit_move_insn (x, y)
568 enum machine_mode outmode, inmode;
572 if (GET_CODE (x) != STRICT_LOW_PART)
574 emit_move_insn (x, y);
579 inner = XEXP (outer, 0);
580 outmode = GET_MODE (outer);
581 inmode = GET_MODE (inner);
582 bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
583 store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y,
584 GET_MODE_BITSIZE (inmode));
587 /* Convert "if (test) x = 1; else x = 0".
589 Only try 0 and STORE_FLAG_VALUE here. Other combinations will be
590 tried in noce_try_store_flag_constants after noce_try_cmove has had
591 a go at the conversion. */
594 noce_try_store_flag (if_info)
595 struct noce_if_info *if_info;
600 if (GET_CODE (if_info->b) == CONST_INT
601 && INTVAL (if_info->b) == STORE_FLAG_VALUE
602 && if_info->a == const0_rtx)
604 else if (if_info->b == const0_rtx
605 && GET_CODE (if_info->a) == CONST_INT
606 && INTVAL (if_info->a) == STORE_FLAG_VALUE
607 && (reversed_comparison_code (if_info->cond, if_info->jump)
615 target = noce_emit_store_flag (if_info, if_info->x, reversep, 0);
618 if (target != if_info->x)
619 noce_emit_move_insn (if_info->x, target);
623 emit_insns_before (seq, if_info->cond_earliest);
634 /* Convert "if (test) x = a; else x = b", for A and B constant. */
637 noce_try_store_flag_constants (if_info)
638 struct noce_if_info *if_info;
642 HOST_WIDE_INT itrue, ifalse, diff, tmp;
643 int normalize, can_reverse;
644 enum machine_mode mode;
647 && GET_CODE (if_info->a) == CONST_INT
648 && GET_CODE (if_info->b) == CONST_INT)
650 mode = GET_MODE (if_info->x);
651 ifalse = INTVAL (if_info->a);
652 itrue = INTVAL (if_info->b);
654 /* Make sure we can represent the difference between the two values. */
655 if ((itrue - ifalse > 0)
656 != ((ifalse < 0) != (itrue < 0) ? ifalse < 0 : ifalse < itrue))
659 diff = trunc_int_for_mode (itrue - ifalse, mode);
661 can_reverse = (reversed_comparison_code (if_info->cond, if_info->jump)
665 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
667 else if (ifalse == 0 && exact_log2 (itrue) >= 0
668 && (STORE_FLAG_VALUE == 1
669 || BRANCH_COST >= 2))
671 else if (itrue == 0 && exact_log2 (ifalse) >= 0 && can_reverse
672 && (STORE_FLAG_VALUE == 1 || BRANCH_COST >= 2))
673 normalize = 1, reversep = 1;
675 && (STORE_FLAG_VALUE == -1
676 || BRANCH_COST >= 2))
678 else if (ifalse == -1 && can_reverse
679 && (STORE_FLAG_VALUE == -1 || BRANCH_COST >= 2))
680 normalize = -1, reversep = 1;
681 else if ((BRANCH_COST >= 2 && STORE_FLAG_VALUE == -1)
689 tmp = itrue; itrue = ifalse; ifalse = tmp;
690 diff = trunc_int_for_mode (-diff, mode);
694 target = noce_emit_store_flag (if_info, if_info->x, reversep, normalize);
701 /* if (test) x = 3; else x = 4;
702 => x = 3 + (test == 0); */
703 if (diff == STORE_FLAG_VALUE || diff == -STORE_FLAG_VALUE)
705 target = expand_simple_binop (mode,
706 (diff == STORE_FLAG_VALUE
708 GEN_INT (ifalse), target, if_info->x, 0,
712 /* if (test) x = 8; else x = 0;
713 => x = (test != 0) << 3; */
714 else if (ifalse == 0 && (tmp = exact_log2 (itrue)) >= 0)
716 target = expand_simple_binop (mode, ASHIFT,
717 target, GEN_INT (tmp), if_info->x, 0,
721 /* if (test) x = -1; else x = b;
722 => x = -(test != 0) | b; */
723 else if (itrue == -1)
725 target = expand_simple_binop (mode, IOR,
726 target, GEN_INT (ifalse), if_info->x, 0,
730 /* if (test) x = a; else x = b;
731 => x = (-(test != 0) & (b - a)) + a; */
734 target = expand_simple_binop (mode, AND,
735 target, GEN_INT (diff), if_info->x, 0,
738 target = expand_simple_binop (mode, PLUS,
739 target, GEN_INT (ifalse),
740 if_info->x, 0, OPTAB_WIDEN);
749 if (target != if_info->x)
750 noce_emit_move_insn (if_info->x, target);
755 if (seq_contains_jump (seq))
758 emit_insns_before (seq, if_info->cond_earliest);
766 /* Convert "if (test) foo++" into "foo += (test != 0)", and
767 similarly for "foo--". */
770 noce_try_store_flag_inc (if_info)
771 struct noce_if_info *if_info;
774 int subtract, normalize;
780 /* Should be no `else' case to worry about. */
781 && if_info->b == if_info->x
782 && GET_CODE (if_info->a) == PLUS
783 && (XEXP (if_info->a, 1) == const1_rtx
784 || XEXP (if_info->a, 1) == constm1_rtx)
785 && rtx_equal_p (XEXP (if_info->a, 0), if_info->x)
786 && (reversed_comparison_code (if_info->cond, if_info->jump)
789 if (STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
790 subtract = 0, normalize = 0;
791 else if (-STORE_FLAG_VALUE == INTVAL (XEXP (if_info->a, 1)))
792 subtract = 1, normalize = 0;
794 subtract = 0, normalize = INTVAL (XEXP (if_info->a, 1));
798 target = noce_emit_store_flag (if_info,
799 gen_reg_rtx (GET_MODE (if_info->x)),
803 target = expand_simple_binop (GET_MODE (if_info->x),
804 subtract ? MINUS : PLUS,
805 if_info->x, target, if_info->x,
809 if (target != if_info->x)
810 noce_emit_move_insn (if_info->x, target);
815 if (seq_contains_jump (seq))
818 emit_insns_before (seq, if_info->cond_earliest);
829 /* Convert "if (test) x = 0;" to "x &= -(test == 0);" */
832 noce_try_store_flag_mask (if_info)
833 struct noce_if_info *if_info;
841 || STORE_FLAG_VALUE == -1)
842 && ((if_info->a == const0_rtx
843 && rtx_equal_p (if_info->b, if_info->x))
844 || ((reversep = (reversed_comparison_code (if_info->cond,
847 && if_info->b == const0_rtx
848 && rtx_equal_p (if_info->a, if_info->x))))
851 target = noce_emit_store_flag (if_info,
852 gen_reg_rtx (GET_MODE (if_info->x)),
855 target = expand_simple_binop (GET_MODE (if_info->x), AND,
856 if_info->x, target, if_info->x, 0,
861 if (target != if_info->x)
862 noce_emit_move_insn (if_info->x, target);
867 if (seq_contains_jump (seq))
870 emit_insns_before (seq, if_info->cond_earliest);
881 /* Helper function for noce_try_cmove and noce_try_cmove_arith. */
884 noce_emit_cmove (if_info, x, code, cmp_a, cmp_b, vfalse, vtrue)
885 struct noce_if_info *if_info;
886 rtx x, cmp_a, cmp_b, vfalse, vtrue;
889 /* If earliest == jump, try to build the cmove insn directly.
890 This is helpful when combine has created some complex condition
891 (like for alpha's cmovlbs) that we can't hope to regenerate
892 through the normal interface. */
894 if (if_info->cond_earliest == if_info->jump)
898 tmp = gen_rtx_fmt_ee (code, GET_MODE (if_info->cond), cmp_a, cmp_b);
899 tmp = gen_rtx_IF_THEN_ELSE (GET_MODE (x), tmp, vtrue, vfalse);
900 tmp = gen_rtx_SET (VOIDmode, x, tmp);
903 tmp = emit_insn (tmp);
905 if (recog_memoized (tmp) >= 0)
917 /* Don't even try if the comparison operands are weird. */
918 if (! general_operand (cmp_a, GET_MODE (cmp_a))
919 || ! general_operand (cmp_b, GET_MODE (cmp_b)))
922 #if HAVE_conditional_move
923 return emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode,
924 vtrue, vfalse, GET_MODE (x),
925 (code == LTU || code == GEU
926 || code == LEU || code == GTU));
928 /* We'll never get here, as noce_process_if_block doesn't call the
929 functions involved. Ifdef code, however, should be discouraged
930 because it leads to typos in the code not selected. However,
931 emit_conditional_move won't exist either. */
936 /* Try only simple constants and registers here. More complex cases
937 are handled in noce_try_cmove_arith after noce_try_store_flag_arith
938 has had a go at it. */
941 noce_try_cmove (if_info)
942 struct noce_if_info *if_info;
947 if ((CONSTANT_P (if_info->a) || register_operand (if_info->a, VOIDmode))
948 && (CONSTANT_P (if_info->b) || register_operand (if_info->b, VOIDmode)))
952 code = GET_CODE (if_info->cond);
953 target = noce_emit_cmove (if_info, if_info->x, code,
954 XEXP (if_info->cond, 0),
955 XEXP (if_info->cond, 1),
956 if_info->a, if_info->b);
960 if (target != if_info->x)
961 noce_emit_move_insn (if_info->x, target);
965 emit_insns_before (seq, if_info->cond_earliest);
978 /* Try more complex cases involving conditional_move. */
981 noce_try_cmove_arith (if_info)
982 struct noce_if_info *if_info;
992 /* A conditional move from two memory sources is equivalent to a
993 conditional on their addresses followed by a load. Don't do this
994 early because it'll screw alias analysis. Note that we've
995 already checked for no side effects. */
996 if (! no_new_pseudos && cse_not_expected
997 && GET_CODE (a) == MEM && GET_CODE (b) == MEM
1002 x = gen_reg_rtx (Pmode);
1006 /* ??? We could handle this if we knew that a load from A or B could
1007 not fault. This is also true if we've already loaded
1008 from the address along the path from ENTRY. */
1009 else if (may_trap_p (a) || may_trap_p (b))
1012 /* if (test) x = a + b; else x = c - d;
1019 code = GET_CODE (if_info->cond);
1020 insn_a = if_info->insn_a;
1021 insn_b = if_info->insn_b;
1023 /* Possibly rearrange operands to make things come out more natural. */
1024 if (reversed_comparison_code (if_info->cond, if_info->jump) != UNKNOWN)
1027 if (rtx_equal_p (b, x))
1029 else if (general_operand (b, GET_MODE (b)))
1034 code = reversed_comparison_code (if_info->cond, if_info->jump);
1035 tmp = a, a = b, b = tmp;
1036 tmp = insn_a, insn_a = insn_b, insn_b = tmp;
1042 /* If either operand is complex, load it into a register first.
1043 The best way to do this is to copy the original insn. In this
1044 way we preserve any clobbers etc that the insn may have had.
1045 This is of course not possible in the IS_MEM case. */
1046 if (! general_operand (a, GET_MODE (a)))
1051 goto end_seq_and_fail;
1055 tmp = gen_reg_rtx (GET_MODE (a));
1056 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, a));
1059 goto end_seq_and_fail;
1062 a = gen_reg_rtx (GET_MODE (a));
1063 tmp = copy_rtx (insn_a);
1064 set = single_set (tmp);
1066 tmp = emit_insn (PATTERN (tmp));
1068 if (recog_memoized (tmp) < 0)
1069 goto end_seq_and_fail;
1071 if (! general_operand (b, GET_MODE (b)))
1076 goto end_seq_and_fail;
1080 tmp = gen_reg_rtx (GET_MODE (b));
1081 tmp = emit_insn (gen_rtx_SET (VOIDmode, tmp, b));
1084 goto end_seq_and_fail;
1087 b = gen_reg_rtx (GET_MODE (b));
1088 tmp = copy_rtx (insn_b);
1089 set = single_set (tmp);
1091 tmp = emit_insn (PATTERN (tmp));
1093 if (recog_memoized (tmp) < 0)
1094 goto end_seq_and_fail;
1097 target = noce_emit_cmove (if_info, x, code, XEXP (if_info->cond, 0),
1098 XEXP (if_info->cond, 1), a, b);
1101 goto end_seq_and_fail;
1103 /* If we're handling a memory for above, emit the load now. */
1106 tmp = gen_rtx_MEM (GET_MODE (if_info->x), target);
1108 /* Copy over flags as appropriate. */
1109 if (MEM_VOLATILE_P (if_info->a) || MEM_VOLATILE_P (if_info->b))
1110 MEM_VOLATILE_P (tmp) = 1;
1111 if (MEM_IN_STRUCT_P (if_info->a) && MEM_IN_STRUCT_P (if_info->b))
1112 MEM_IN_STRUCT_P (tmp) = 1;
1113 if (MEM_SCALAR_P (if_info->a) && MEM_SCALAR_P (if_info->b))
1114 MEM_SCALAR_P (tmp) = 1;
1115 if (MEM_ALIAS_SET (if_info->a) == MEM_ALIAS_SET (if_info->b))
1116 set_mem_alias_set (tmp, MEM_ALIAS_SET (if_info->a));
1118 MIN (MEM_ALIGN (if_info->a), MEM_ALIGN (if_info->b)));
1120 noce_emit_move_insn (if_info->x, tmp);
1122 else if (target != x)
1123 noce_emit_move_insn (x, target);
1127 emit_insns_before (tmp, if_info->cond_earliest);
1135 /* For most cases, the simplified condition we found is the best
1136 choice, but this is not the case for the min/max/abs transforms.
1137 For these we wish to know that it is A or B in the condition. */
1140 noce_get_alt_condition (if_info, target, earliest)
1141 struct noce_if_info *if_info;
1145 rtx cond, set, insn;
1148 /* If target is already mentioned in the known condition, return it. */
1149 if (reg_mentioned_p (target, if_info->cond))
1151 *earliest = if_info->cond_earliest;
1152 return if_info->cond;
1155 set = pc_set (if_info->jump);
1156 cond = XEXP (SET_SRC (set), 0);
1158 = GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1159 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (if_info->jump);
1161 /* If we're looking for a constant, try to make the conditional
1162 have that constant in it. There are two reasons why it may
1163 not have the constant we want:
1165 1. GCC may have needed to put the constant in a register, because
1166 the target can't compare directly against that constant. For
1167 this case, we look for a SET immediately before the comparison
1168 that puts a constant in that register.
1170 2. GCC may have canonicalized the conditional, for example
1171 replacing "if x < 4" with "if x <= 3". We can undo that (or
1172 make equivalent types of changes) to get the constants we need
1173 if they're off by one in the right direction. */
1175 if (GET_CODE (target) == CONST_INT)
1177 enum rtx_code code = GET_CODE (if_info->cond);
1178 rtx op_a = XEXP (if_info->cond, 0);
1179 rtx op_b = XEXP (if_info->cond, 1);
1182 /* First, look to see if we put a constant in a register. */
1183 prev_insn = PREV_INSN (if_info->cond_earliest);
1185 && INSN_P (prev_insn)
1186 && GET_CODE (PATTERN (prev_insn)) == SET)
1188 rtx src = find_reg_equal_equiv_note (prev_insn);
1190 src = SET_SRC (PATTERN (prev_insn));
1191 if (GET_CODE (src) == CONST_INT)
1193 if (rtx_equal_p (op_a, SET_DEST (PATTERN (prev_insn))))
1195 else if (rtx_equal_p (op_b, SET_DEST (PATTERN (prev_insn))))
1198 if (GET_CODE (op_a) == CONST_INT)
1203 code = swap_condition (code);
1208 /* Now, look to see if we can get the right constant by
1209 adjusting the conditional. */
1210 if (GET_CODE (op_b) == CONST_INT)
1212 HOST_WIDE_INT desired_val = INTVAL (target);
1213 HOST_WIDE_INT actual_val = INTVAL (op_b);
1218 if (actual_val == desired_val + 1)
1221 op_b = GEN_INT (desired_val);
1225 if (actual_val == desired_val - 1)
1228 op_b = GEN_INT (desired_val);
1232 if (actual_val == desired_val - 1)
1235 op_b = GEN_INT (desired_val);
1239 if (actual_val == desired_val + 1)
1242 op_b = GEN_INT (desired_val);
1250 /* If we made any changes, generate a new conditional that is
1251 equivalent to what we started with, but has the right
1253 if (code != GET_CODE (if_info->cond)
1254 || op_a != XEXP (if_info->cond, 0)
1255 || op_b != XEXP (if_info->cond, 1))
1257 cond = gen_rtx_fmt_ee (code, GET_MODE (cond), op_a, op_b);
1258 *earliest = if_info->cond_earliest;
1263 cond = canonicalize_condition (if_info->jump, cond, reverse,
1265 if (! cond || ! reg_mentioned_p (target, cond))
1268 /* We almost certainly searched back to a different place.
1269 Need to re-verify correct lifetimes. */
1271 /* X may not be mentioned in the range (cond_earliest, jump]. */
1272 for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
1273 if (INSN_P (insn) && reg_mentioned_p (if_info->x, insn))
1276 /* A and B may not be modified in the range [cond_earliest, jump). */
1277 for (insn = *earliest; insn != if_info->jump; insn = NEXT_INSN (insn))
1279 && (modified_in_p (if_info->a, insn)
1280 || modified_in_p (if_info->b, insn)))
1286 /* Convert "if (a < b) x = a; else x = b;" to "x = min(a, b);", etc. */
1289 noce_try_minmax (if_info)
1290 struct noce_if_info *if_info;
1292 rtx cond, earliest, target, seq;
1293 enum rtx_code code, op;
1296 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1300 /* ??? Reject modes with NaNs or signed zeros since we don't know how
1301 they will be resolved with an SMIN/SMAX. It wouldn't be too hard
1302 to get the target to tell us... */
1303 if (HONOR_SIGNED_ZEROS (GET_MODE (if_info->x))
1304 || HONOR_NANS (GET_MODE (if_info->x)))
1307 cond = noce_get_alt_condition (if_info, if_info->a, &earliest);
1311 /* Verify the condition is of the form we expect, and canonicalize
1312 the comparison code. */
1313 code = GET_CODE (cond);
1314 if (rtx_equal_p (XEXP (cond, 0), if_info->a))
1316 if (! rtx_equal_p (XEXP (cond, 1), if_info->b))
1319 else if (rtx_equal_p (XEXP (cond, 1), if_info->a))
1321 if (! rtx_equal_p (XEXP (cond, 0), if_info->b))
1323 code = swap_condition (code);
1328 /* Determine what sort of operation this is. Note that the code is for
1329 a taken branch, so the code->operation mapping appears backwards. */
1362 target = expand_simple_binop (GET_MODE (if_info->x), op,
1363 if_info->a, if_info->b,
1364 if_info->x, unsignedp, OPTAB_WIDEN);
1370 if (target != if_info->x)
1371 noce_emit_move_insn (if_info->x, target);
1376 if (seq_contains_jump (seq))
1379 emit_insns_before (seq, earliest);
1380 if_info->cond = cond;
1381 if_info->cond_earliest = earliest;
1386 /* Convert "if (a < 0) x = -a; else x = a;" to "x = abs(a);", etc. */
1389 noce_try_abs (if_info)
1390 struct noce_if_info *if_info;
1392 rtx cond, earliest, target, seq, a, b, c;
1395 /* ??? Can't guarantee that expand_binop won't create pseudos. */
1399 /* Recognize A and B as constituting an ABS or NABS. */
1402 if (GET_CODE (a) == NEG && rtx_equal_p (XEXP (a, 0), b))
1404 else if (GET_CODE (b) == NEG && rtx_equal_p (XEXP (b, 0), a))
1406 c = a; a = b; b = c;
1412 cond = noce_get_alt_condition (if_info, b, &earliest);
1416 /* Verify the condition is of the form we expect. */
1417 if (rtx_equal_p (XEXP (cond, 0), b))
1419 else if (rtx_equal_p (XEXP (cond, 1), b))
1424 /* Verify that C is zero. Search backward through the block for
1425 a REG_EQUAL note if necessary. */
1428 rtx insn, note = NULL;
1429 for (insn = earliest;
1430 insn != if_info->test_bb->head;
1431 insn = PREV_INSN (insn))
1433 && ((note = find_reg_note (insn, REG_EQUAL, c))
1434 || (note = find_reg_note (insn, REG_EQUIV, c))))
1440 if (GET_CODE (c) == MEM
1441 && GET_CODE (XEXP (c, 0)) == SYMBOL_REF
1442 && CONSTANT_POOL_ADDRESS_P (XEXP (c, 0)))
1443 c = get_pool_constant (XEXP (c, 0));
1445 /* Work around funny ideas get_condition has wrt canonicalization.
1446 Note that these rtx constants are known to be CONST_INT, and
1447 therefore imply integer comparisons. */
1448 if (c == constm1_rtx && GET_CODE (cond) == GT)
1450 else if (c == const1_rtx && GET_CODE (cond) == LT)
1452 else if (c != CONST0_RTX (GET_MODE (b)))
1455 /* Determine what sort of operation this is. */
1456 switch (GET_CODE (cond))
1475 target = expand_simple_unop (GET_MODE (if_info->x), ABS, b, if_info->x, 0);
1477 /* ??? It's a quandry whether cmove would be better here, especially
1478 for integers. Perhaps combine will clean things up. */
1479 if (target && negate)
1480 target = expand_simple_unop (GET_MODE (target), NEG, target, if_info->x, 0);
1488 if (target != if_info->x)
1489 noce_emit_move_insn (if_info->x, target);
1494 if (seq_contains_jump (seq))
1497 emit_insns_before (seq, earliest);
1498 if_info->cond = cond;
1499 if_info->cond_earliest = earliest;
1504 /* Look for the condition for the jump first. We'd prefer to avoid
1505 get_condition if we can -- it tries to look back for the contents
1506 of an original compare. On targets that use normal integers for
1507 comparisons, e.g. alpha, this is wasteful. */
1510 noce_get_condition (jump, earliest)
1517 /* If the condition variable is a register and is MODE_INT, accept it.
1518 Otherwise, fall back on get_condition. */
1520 if (! any_condjump_p (jump))
1523 set = pc_set (jump);
1525 cond = XEXP (SET_SRC (set), 0);
1526 if (GET_CODE (XEXP (cond, 0)) == REG
1527 && GET_MODE_CLASS (GET_MODE (XEXP (cond, 0))) == MODE_INT)
1531 /* If this branches to JUMP_LABEL when the condition is false,
1532 reverse the condition. */
1533 if (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
1534 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump))
1535 cond = gen_rtx_fmt_ee (reverse_condition (GET_CODE (cond)),
1536 GET_MODE (cond), XEXP (cond, 0),
1540 cond = get_condition (jump, earliest);
1545 /* Return true if OP is ok for if-then-else processing. */
1548 noce_operand_ok (op)
1551 /* We special-case memories, so handle any of them with
1552 no address side effects. */
1553 if (GET_CODE (op) == MEM)
1554 return ! side_effects_p (XEXP (op, 0));
1556 if (side_effects_p (op))
1559 return ! may_trap_p (op);
1562 /* Given a simple IF-THEN or IF-THEN-ELSE block, attempt to convert it
1563 without using conditional execution. Return TRUE if we were
1564 successful at converting the the block. */
1567 noce_process_if_block (test_bb, then_bb, else_bb, join_bb)
1568 basic_block test_bb; /* Basic block test is in */
1569 basic_block then_bb; /* Basic block for THEN block */
1570 basic_block else_bb; /* Basic block for ELSE block */
1571 basic_block join_bb; /* Basic block the join label is in */
1573 /* We're looking for patterns of the form
1575 (1) if (...) x = a; else x = b;
1576 (2) x = b; if (...) x = a;
1577 (3) if (...) x = a; // as if with an initial x = x.
1579 The later patterns require jumps to be more expensive.
1581 ??? For future expansion, look for multiple X in such patterns. */
1583 struct noce_if_info if_info;
1586 rtx orig_x, x, a, b;
1587 rtx jump, cond, insn;
1589 /* If this is not a standard conditional jump, we can't parse it. */
1590 jump = test_bb->end;
1591 cond = noce_get_condition (jump, &if_info.cond_earliest);
1595 /* If the conditional jump is more than just a conditional jump,
1596 then we can not do if-conversion on this block. */
1597 if (! onlyjump_p (jump))
1600 /* We must be comparing objects whose modes imply the size. */
1601 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
1604 /* Look for one of the potential sets. */
1605 insn_a = first_active_insn (then_bb);
1607 || ! last_active_insn_p (then_bb, insn_a)
1608 || (set_a = single_set (insn_a)) == NULL_RTX)
1611 x = SET_DEST (set_a);
1612 a = SET_SRC (set_a);
1614 /* Look for the other potential set. Make sure we've got equivalent
1616 /* ??? This is overconservative. Storing to two different mems is
1617 as easy as conditionally computing the address. Storing to a
1618 single mem merely requires a scratch memory to use as one of the
1619 destination addresses; often the memory immediately below the
1620 stack pointer is available for this. */
1624 insn_b = first_active_insn (else_bb);
1626 || ! last_active_insn_p (else_bb, insn_b)
1627 || (set_b = single_set (insn_b)) == NULL_RTX
1628 || ! rtx_equal_p (x, SET_DEST (set_b)))
1633 insn_b = prev_nonnote_insn (if_info.cond_earliest);
1635 || GET_CODE (insn_b) != INSN
1636 || (set_b = single_set (insn_b)) == NULL_RTX
1637 || ! rtx_equal_p (x, SET_DEST (set_b))
1638 || reg_mentioned_p (x, cond)
1639 || reg_mentioned_p (x, a)
1640 || reg_mentioned_p (x, SET_SRC (set_b)))
1641 insn_b = set_b = NULL_RTX;
1643 b = (set_b ? SET_SRC (set_b) : x);
1645 /* X may not be mentioned in the range (cond_earliest, jump]. */
1646 for (insn = jump; insn != if_info.cond_earliest; insn = PREV_INSN (insn))
1647 if (INSN_P (insn) && reg_mentioned_p (x, insn))
1650 /* A and B may not be modified in the range [cond_earliest, jump). */
1651 for (insn = if_info.cond_earliest; insn != jump; insn = NEXT_INSN (insn))
1653 && (modified_in_p (a, insn) || modified_in_p (b, insn)))
1656 /* Only operate on register destinations, and even then avoid extending
1657 the lifetime of hard registers on small register class machines. */
1659 if (GET_CODE (x) != REG
1660 || (SMALL_REGISTER_CLASSES
1661 && REGNO (x) < FIRST_PSEUDO_REGISTER))
1665 x = gen_reg_rtx (GET_MODE (GET_CODE (x) == STRICT_LOW_PART
1666 ? XEXP (x, 0) : x));
1669 /* Don't operate on sources that may trap or are volatile. */
1670 if (! noce_operand_ok (a) || ! noce_operand_ok (b))
1673 /* Set up the info block for our subroutines. */
1674 if_info.test_bb = test_bb;
1675 if_info.cond = cond;
1676 if_info.jump = jump;
1677 if_info.insn_a = insn_a;
1678 if_info.insn_b = insn_b;
1683 /* Try optimizations in some approximation of a useful order. */
1684 /* ??? Should first look to see if X is live incoming at all. If it
1685 isn't, we don't need anything but an unconditional set. */
1687 /* Look and see if A and B are really the same. Avoid creating silly
1688 cmove constructs that no one will fix up later. */
1689 if (rtx_equal_p (a, b))
1691 /* If we have an INSN_B, we don't have to create any new rtl. Just
1692 move the instruction that we already have. If we don't have an
1693 INSN_B, that means that A == X, and we've got a noop move. In
1694 that case don't do anything and let the code below delete INSN_A. */
1695 if (insn_b && else_bb)
1699 if (else_bb && insn_b == else_bb->end)
1700 else_bb->end = PREV_INSN (insn_b);
1701 reorder_insns (insn_b, insn_b, PREV_INSN (if_info.cond_earliest));
1703 /* If there was a REG_EQUAL note, delete it since it may have been
1704 true due to this insn being after a jump. */
1705 if ((note = find_reg_note (insn_b, REG_EQUAL, NULL_RTX)) != 0)
1706 remove_note (insn_b, note);
1710 /* If we have "x = b; if (...) x = a;", and x has side-effects, then
1711 x must be executed twice. */
1712 else if (insn_b && side_effects_p (orig_x))
1719 if (noce_try_store_flag (&if_info))
1721 if (noce_try_minmax (&if_info))
1723 if (noce_try_abs (&if_info))
1725 if (HAVE_conditional_move
1726 && noce_try_cmove (&if_info))
1728 if (! HAVE_conditional_execution)
1730 if (noce_try_store_flag_constants (&if_info))
1732 if (noce_try_store_flag_inc (&if_info))
1734 if (noce_try_store_flag_mask (&if_info))
1736 if (HAVE_conditional_move
1737 && noce_try_cmove_arith (&if_info))
1744 /* The original sets may now be killed. */
1745 delete_insn (insn_a);
1747 /* Several special cases here: First, we may have reused insn_b above,
1748 in which case insn_b is now NULL. Second, we want to delete insn_b
1749 if it came from the ELSE block, because follows the now correct
1750 write that appears in the TEST block. However, if we got insn_b from
1751 the TEST block, it may in fact be loading data needed for the comparison.
1752 We'll let life_analysis remove the insn if it's really dead. */
1753 if (insn_b && else_bb)
1754 delete_insn (insn_b);
1756 /* The new insns will have been inserted before cond_earliest. We should
1757 be able to remove the jump with impunity, but the condition itself may
1758 have been modified by gcse to be shared across basic blocks. */
1761 /* If we used a temporary, fix it up now. */
1765 noce_emit_move_insn (copy_rtx (orig_x), x);
1766 insn_b = gen_sequence ();
1769 emit_insn_after (insn_b, test_bb->end);
1772 /* Merge the blocks! */
1773 merge_if_block (test_bb, then_bb, else_bb, join_bb);
1778 /* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
1779 straight line code. Return true if successful. */
1782 process_if_block (test_bb, then_bb, else_bb, join_bb)
1783 basic_block test_bb; /* Basic block test is in */
1784 basic_block then_bb; /* Basic block for THEN block */
1785 basic_block else_bb; /* Basic block for ELSE block */
1786 basic_block join_bb; /* Basic block the join label is in */
1788 if (! reload_completed
1789 && noce_process_if_block (test_bb, then_bb, else_bb, join_bb))
1792 if (HAVE_conditional_execution
1794 && cond_exec_process_if_block (test_bb, then_bb, else_bb, join_bb))
1800 /* Merge the blocks and mark for local life update. */
1803 merge_if_block (test_bb, then_bb, else_bb, join_bb)
1804 basic_block test_bb; /* Basic block test is in */
1805 basic_block then_bb; /* Basic block for THEN block */
1806 basic_block else_bb; /* Basic block for ELSE block */
1807 basic_block join_bb; /* Basic block the join label is in */
1809 basic_block combo_bb;
1811 /* All block merging is done into the lower block numbers. */
1815 /* First merge TEST block into THEN block. This is a no-brainer since
1816 the THEN block did not have a code label to begin with. */
1819 if (combo_bb->global_live_at_end)
1820 COPY_REG_SET (combo_bb->global_live_at_end,
1821 then_bb->global_live_at_end);
1822 merge_blocks_nomove (combo_bb, then_bb);
1823 num_removed_blocks++;
1826 /* The ELSE block, if it existed, had a label. That label count
1827 will almost always be zero, but odd things can happen when labels
1828 get their addresses taken. */
1831 merge_blocks_nomove (combo_bb, else_bb);
1832 num_removed_blocks++;
1835 /* If there was no join block reported, that means it was not adjacent
1836 to the others, and so we cannot merge them. */
1840 rtx last = combo_bb->end;
1842 /* The outgoing edge for the current COMBO block should already
1843 be correct. Verify this. */
1844 if (combo_bb->succ == NULL_EDGE)
1846 if (find_reg_note (last, REG_NORETURN, NULL))
1848 else if (GET_CODE (last) == INSN
1849 && GET_CODE (PATTERN (last)) == TRAP_IF
1850 && TRAP_CONDITION (PATTERN (last)) == const_true_rtx)
1856 /* There should still be something at the end of the THEN or ELSE
1857 blocks taking us to our final destination. */
1858 else if (GET_CODE (last) == JUMP_INSN)
1860 else if (combo_bb->succ->dest == EXIT_BLOCK_PTR
1861 && GET_CODE (last) == CALL_INSN
1862 && SIBLING_CALL_P (last))
1864 else if ((combo_bb->succ->flags & EDGE_EH)
1865 && can_throw_internal (last))
1871 /* The JOIN block may have had quite a number of other predecessors too.
1872 Since we've already merged the TEST, THEN and ELSE blocks, we should
1873 have only one remaining edge from our if-then-else diamond. If there
1874 is more than one remaining edge, it must come from elsewhere. There
1875 may be zero incoming edges if the THEN block didn't actually join
1876 back up (as with a call to abort). */
1877 else if ((join_bb->pred == NULL
1878 || join_bb->pred->pred_next == NULL)
1879 && join_bb != EXIT_BLOCK_PTR)
1881 /* We can merge the JOIN. */
1882 if (combo_bb->global_live_at_end)
1883 COPY_REG_SET (combo_bb->global_live_at_end,
1884 join_bb->global_live_at_end);
1885 merge_blocks_nomove (combo_bb, join_bb);
1886 num_removed_blocks++;
1890 /* We cannot merge the JOIN. */
1892 /* The outgoing edge for the current COMBO block should already
1893 be correct. Verify this. */
1894 if (combo_bb->succ->succ_next != NULL_EDGE
1895 || combo_bb->succ->dest != join_bb)
1898 /* Remove the jump and cruft from the end of the COMBO block. */
1899 if (join_bb != EXIT_BLOCK_PTR)
1900 tidy_fallthru_edge (combo_bb->succ, combo_bb, join_bb);
1903 num_updated_if_blocks++;
1906 /* Find a block ending in a simple IF condition. Return TRUE if
1907 we were able to transform it in some way. */
1910 find_if_header (test_bb)
1911 basic_block test_bb;
1916 /* The kind of block we're looking for has exactly two successors. */
1917 if ((then_edge = test_bb->succ) == NULL_EDGE
1918 || (else_edge = then_edge->succ_next) == NULL_EDGE
1919 || else_edge->succ_next != NULL_EDGE)
1922 /* Neither edge should be abnormal. */
1923 if ((then_edge->flags & EDGE_COMPLEX)
1924 || (else_edge->flags & EDGE_COMPLEX))
1927 /* The THEN edge is canonically the one that falls through. */
1928 if (then_edge->flags & EDGE_FALLTHRU)
1930 else if (else_edge->flags & EDGE_FALLTHRU)
1933 else_edge = then_edge;
1937 /* Otherwise this must be a multiway branch of some sort. */
1940 if (find_if_block (test_bb, then_edge, else_edge))
1942 if (HAVE_trap && HAVE_conditional_trap
1943 && find_cond_trap (test_bb, then_edge, else_edge))
1946 && (! HAVE_conditional_execution || reload_completed))
1948 if (find_if_case_1 (test_bb, then_edge, else_edge))
1950 if (find_if_case_2 (test_bb, then_edge, else_edge))
1958 fprintf (rtl_dump_file, "Conversion succeeded.\n");
1962 /* Determine if a given basic block heads a simple IF-THEN or IF-THEN-ELSE
1963 block. If so, we'll try to convert the insns to not require the branch.
1964 Return TRUE if we were successful at converting the the block. */
1967 find_if_block (test_bb, then_edge, else_edge)
1968 basic_block test_bb;
1969 edge then_edge, else_edge;
1971 basic_block then_bb = then_edge->dest;
1972 basic_block else_bb = else_edge->dest;
1973 basic_block join_bb = NULL_BLOCK;
1974 edge then_succ = then_bb->succ;
1975 edge else_succ = else_bb->succ;
1978 /* The THEN block of an IF-THEN combo must have exactly one predecessor. */
1979 if (then_bb->pred->pred_next != NULL_EDGE)
1982 /* The THEN block of an IF-THEN combo must have zero or one successors. */
1983 if (then_succ != NULL_EDGE
1984 && (then_succ->succ_next != NULL_EDGE
1985 || (then_succ->flags & EDGE_COMPLEX)))
1988 /* If the THEN block has no successors, conditional execution can still
1989 make a conditional call. Don't do this unless the ELSE block has
1990 only one incoming edge -- the CFG manipulation is too ugly otherwise.
1991 Check for the last insn of the THEN block being an indirect jump, which
1992 is listed as not having any successors, but confuses the rest of the CE
1993 code processing. XXX we should fix this in the future. */
1994 if (then_succ == NULL)
1996 if (else_bb->pred->pred_next == NULL_EDGE)
1998 rtx last_insn = then_bb->end;
2001 && GET_CODE (last_insn) == NOTE
2002 && last_insn != then_bb->head)
2003 last_insn = PREV_INSN (last_insn);
2006 && GET_CODE (last_insn) == JUMP_INSN
2007 && ! simplejump_p (last_insn))
2011 else_bb = NULL_BLOCK;
2017 /* If the THEN block's successor is the other edge out of the TEST block,
2018 then we have an IF-THEN combo without an ELSE. */
2019 else if (then_succ->dest == else_bb)
2022 else_bb = NULL_BLOCK;
2025 /* If the THEN and ELSE block meet in a subsequent block, and the ELSE
2026 has exactly one predecessor and one successor, and the outgoing edge
2027 is not complex, then we have an IF-THEN-ELSE combo. */
2028 else if (else_succ != NULL_EDGE
2029 && then_succ->dest == else_succ->dest
2030 && else_bb->pred->pred_next == NULL_EDGE
2031 && else_succ->succ_next == NULL_EDGE
2032 && ! (else_succ->flags & EDGE_COMPLEX))
2033 join_bb = else_succ->dest;
2035 /* Otherwise it is not an IF-THEN or IF-THEN-ELSE combination. */
2039 num_possible_if_blocks++;
2044 fprintf (rtl_dump_file,
2045 "\nIF-THEN-ELSE block found, start %d, then %d, else %d, join %d\n",
2046 test_bb->index, then_bb->index, else_bb->index,
2049 fprintf (rtl_dump_file,
2050 "\nIF-THEN block found, start %d, then %d, join %d\n",
2051 test_bb->index, then_bb->index, join_bb->index);
2054 /* Make sure IF, THEN, and ELSE, blocks are adjacent. Actually, we
2055 get the first condition for free, since we've already asserted that
2056 there's a fallthru edge from IF to THEN. */
2057 /* ??? As an enhancement, move the ELSE block. Have to deal with
2058 BLOCK notes, if by no other means than aborting the merge if they
2059 exist. Sticky enough I don't want to think about it now. */
2060 next_index = then_bb->index;
2061 if (else_bb && ++next_index != else_bb->index)
2063 if (++next_index != join_bb->index && join_bb->index != EXIT_BLOCK)
2071 /* Do the real work. */
2072 return process_if_block (test_bb, then_bb, else_bb, join_bb);
2075 /* Convert a branch over a trap, or a branch to a trap,
2076 into a conditional trap. */
2079 find_cond_trap (test_bb, then_edge, else_edge)
2080 basic_block test_bb;
2081 edge then_edge, else_edge;
2083 basic_block then_bb, else_bb, join_bb, trap_bb;
2084 rtx trap, jump, cond, cond_earliest, seq;
2087 then_bb = then_edge->dest;
2088 else_bb = else_edge->dest;
2091 /* Locate the block with the trap instruction. */
2092 /* ??? While we look for no successors, we really ought to allow
2093 EH successors. Need to fix merge_if_block for that to work. */
2094 /* ??? We can't currently handle merging the blocks if they are not
2095 already adjacent. Prevent losage in merge_if_block by detecting
2097 if ((trap = block_has_only_trap (then_bb)) != NULL)
2100 if (else_bb->index != then_bb->index + 1)
2105 else if ((trap = block_has_only_trap (else_bb)) != NULL)
2108 if (else_bb->index != then_bb->index + 1)
2110 else if (then_bb->succ
2111 && ! then_bb->succ->succ_next
2112 && ! (then_bb->succ->flags & EDGE_COMPLEX)
2113 && then_bb->succ->dest->index == else_bb->index + 1)
2114 join_bb = then_bb->succ->dest;
2121 if (trap_bb == then_bb)
2122 fprintf (rtl_dump_file,
2123 "\nTRAP-IF block found, start %d, trap %d",
2124 test_bb->index, then_bb->index);
2126 fprintf (rtl_dump_file,
2127 "\nTRAP-IF block found, start %d, then %d, trap %d",
2128 test_bb->index, then_bb->index, trap_bb->index);
2130 fprintf (rtl_dump_file, ", join %d\n", join_bb->index);
2132 fputc ('\n', rtl_dump_file);
2135 /* If this is not a standard conditional jump, we can't parse it. */
2136 jump = test_bb->end;
2137 cond = noce_get_condition (jump, &cond_earliest);
2141 /* If the conditional jump is more than just a conditional jump,
2142 then we can not do if-conversion on this block. */
2143 if (! onlyjump_p (jump))
2146 /* We must be comparing objects whose modes imply the size. */
2147 if (GET_MODE (XEXP (cond, 0)) == BLKmode)
2150 /* Reverse the comparison code, if necessary. */
2151 code = GET_CODE (cond);
2152 if (then_bb == trap_bb)
2154 code = reversed_comparison_code (cond, jump);
2155 if (code == UNKNOWN)
2159 /* Attempt to generate the conditional trap. */
2160 seq = gen_cond_trap (code, XEXP (cond, 0), XEXP (cond, 1),
2161 TRAP_CODE (PATTERN (trap)));
2165 /* Emit the new insns before cond_earliest; delete the old jump. */
2166 emit_insn_before (seq, cond_earliest);
2169 /* Delete the trap block together with its insn. */
2170 if (trap_bb == then_bb)
2172 else if (else_bb == NULL)
2174 else if (trap_bb == else_bb)
2178 flow_delete_block (trap_bb);
2179 num_removed_blocks++;
2181 /* Merge what's left. */
2182 merge_if_block (test_bb, then_bb, else_bb, join_bb);
2187 /* Subroutine of find_cond_trap: if BB contains only a trap insn,
2191 block_has_only_trap (bb)
2196 /* We're not the exit block. */
2197 if (bb == EXIT_BLOCK_PTR)
2200 /* The block must have no successors. */
2204 /* The only instruction in the THEN block must be the trap. */
2205 trap = first_active_insn (bb);
2206 if (! (trap == bb->end
2207 && GET_CODE (PATTERN (trap)) == TRAP_IF
2208 && TRAP_CONDITION (PATTERN (trap)) == const_true_rtx))
2214 /* Look for IF-THEN-ELSE cases in which one of THEN or ELSE is
2215 transformable, but not necessarily the other. There need be no
2218 Return TRUE if we were successful at converting the the block.
2220 Cases we'd like to look at:
2223 if (test) goto over; // x not live
2231 if (! test) goto label;
2234 if (test) goto E; // x not live
2248 (3) // This one's really only interesting for targets that can do
2249 // multiway branching, e.g. IA-64 BBB bundles. For other targets
2250 // it results in multiple branches on a cache line, which often
2251 // does not sit well with predictors.
2253 if (test1) goto E; // predicted not taken
2269 (A) Don't do (2) if the branch is predicted against the block we're
2270 eliminating. Do it anyway if we can eliminate a branch; this requires
2271 that the sole successor of the eliminated block postdominate the other
2274 (B) With CE, on (3) we can steal from both sides of the if, creating
2283 Again, this is most useful if J postdominates.
2285 (C) CE substitutes for helpful life information.
2287 (D) These heuristics need a lot of work. */
2289 /* Tests for case 1 above. */
2292 find_if_case_1 (test_bb, then_edge, else_edge)
2293 basic_block test_bb;
2294 edge then_edge, else_edge;
2296 basic_block then_bb = then_edge->dest;
2297 basic_block else_bb = else_edge->dest, new_bb;
2298 edge then_succ = then_bb->succ;
2300 /* THEN has one successor. */
2301 if (!then_succ || then_succ->succ_next != NULL)
2304 /* THEN does not fall through, but is not strange either. */
2305 if (then_succ->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))
2308 /* THEN has one predecessor. */
2309 if (then_bb->pred->pred_next != NULL)
2312 /* THEN must do something. */
2313 if (forwarder_block_p (then_bb))
2316 num_possible_if_blocks++;
2318 fprintf (rtl_dump_file,
2319 "\nIF-CASE-1 found, start %d, then %d\n",
2320 test_bb->index, then_bb->index);
2322 /* THEN is small. */
2323 if (count_bb_insns (then_bb) > BRANCH_COST)
2326 /* Registers set are dead, or are predicable. */
2327 if (! dead_or_predicable (test_bb, then_bb, else_bb,
2328 then_bb->succ->dest, 1))
2331 /* Conversion went ok, including moving the insns and fixing up the
2332 jump. Adjust the CFG to match. */
2334 bitmap_operation (test_bb->global_live_at_end,
2335 else_bb->global_live_at_start,
2336 then_bb->global_live_at_end, BITMAP_IOR);
2338 new_bb = redirect_edge_and_branch_force (FALLTHRU_EDGE (test_bb), else_bb);
2339 /* Make rest of code believe that the newly created block is the THEN_BB
2340 block we are going to remove. */
2342 new_bb->aux = then_bb->aux;
2343 flow_delete_block (then_bb);
2344 /* We've possibly created jump to next insn, cleanup_cfg will solve that
2347 num_removed_blocks++;
2348 num_updated_if_blocks++;
2353 /* Test for case 2 above. */
2356 find_if_case_2 (test_bb, then_edge, else_edge)
2357 basic_block test_bb;
2358 edge then_edge, else_edge;
2360 basic_block then_bb = then_edge->dest;
2361 basic_block else_bb = else_edge->dest;
2362 edge else_succ = else_bb->succ;
2365 /* ELSE has one successor. */
2366 if (!else_succ || else_succ->succ_next != NULL)
2369 /* ELSE outgoing edge is not complex. */
2370 if (else_succ->flags & EDGE_COMPLEX)
2373 /* ELSE has one predecessor. */
2374 if (else_bb->pred->pred_next != NULL)
2377 /* THEN is not EXIT. */
2378 if (then_bb->index < 0)
2381 /* ELSE is predicted or SUCC(ELSE) postdominates THEN. */
2382 note = find_reg_note (test_bb->end, REG_BR_PROB, NULL_RTX);
2383 if (note && INTVAL (XEXP (note, 0)) >= REG_BR_PROB_BASE / 2)
2385 else if (else_succ->dest->index < 0
2386 || TEST_BIT (post_dominators[ORIG_INDEX (then_bb)],
2387 ORIG_INDEX (else_succ->dest)))
2392 num_possible_if_blocks++;
2394 fprintf (rtl_dump_file,
2395 "\nIF-CASE-2 found, start %d, else %d\n",
2396 test_bb->index, else_bb->index);
2398 /* ELSE is small. */
2399 if (count_bb_insns (then_bb) > BRANCH_COST)
2402 /* Registers set are dead, or are predicable. */
2403 if (! dead_or_predicable (test_bb, else_bb, then_bb, else_succ->dest, 0))
2406 /* Conversion went ok, including moving the insns and fixing up the
2407 jump. Adjust the CFG to match. */
2409 bitmap_operation (test_bb->global_live_at_end,
2410 then_bb->global_live_at_start,
2411 else_bb->global_live_at_end, BITMAP_IOR);
2413 flow_delete_block (else_bb);
2415 num_removed_blocks++;
2416 num_updated_if_blocks++;
2418 /* ??? We may now fallthru from one of THEN's successors into a join
2419 block. Rerun cleanup_cfg? Examine things manually? Wait? */
2424 /* A subroutine of dead_or_predicable called through for_each_rtx.
2425 Return 1 if a memory is found. */
2428 find_memory (px, data)
2430 void *data ATTRIBUTE_UNUSED;
2432 return GET_CODE (*px) == MEM;
2435 /* Used by the code above to perform the actual rtl transformations.
2436 Return TRUE if successful.
2438 TEST_BB is the block containing the conditional branch. MERGE_BB
2439 is the block containing the code to manipulate. NEW_DEST is the
2440 label TEST_BB should be branching to after the conversion.
2441 REVERSEP is true if the sense of the branch should be reversed. */
2444 dead_or_predicable (test_bb, merge_bb, other_bb, new_dest, reversep)
2445 basic_block test_bb, merge_bb, other_bb;
2446 basic_block new_dest;
2449 rtx head, end, jump, earliest, old_dest, new_label = NULL_RTX;
2451 jump = test_bb->end;
2453 /* Find the extent of the real code in the merge block. */
2454 head = merge_bb->head;
2455 end = merge_bb->end;
2457 if (GET_CODE (head) == CODE_LABEL)
2458 head = NEXT_INSN (head);
2459 if (GET_CODE (head) == NOTE)
2463 head = end = NULL_RTX;
2466 head = NEXT_INSN (head);
2469 if (GET_CODE (end) == JUMP_INSN)
2473 head = end = NULL_RTX;
2476 end = PREV_INSN (end);
2479 /* Disable handling dead code by conditional execution if the machine needs
2480 to do anything funny with the tests, etc. */
2481 #ifndef IFCVT_MODIFY_TESTS
2482 if (HAVE_conditional_execution)
2484 /* In the conditional execution case, we have things easy. We know
2485 the condition is reversable. We don't have to check life info,
2486 becase we're going to conditionally execute the code anyway.
2487 All that's left is making sure the insns involved can actually
2492 cond = cond_exec_get_condition (jump);
2496 prob_val = find_reg_note (jump, REG_BR_PROB, NULL_RTX);
2498 prob_val = XEXP (prob_val, 0);
2502 enum rtx_code rev = reversed_comparison_code (cond, jump);
2505 cond = gen_rtx_fmt_ee (rev, GET_MODE (cond), XEXP (cond, 0),
2508 prob_val = GEN_INT (REG_BR_PROB_BASE - INTVAL (prob_val));
2511 if (! cond_exec_process_insns (head, end, cond, prob_val, 0))
2519 /* In the non-conditional execution case, we have to verify that there
2520 are no trapping operations, no calls, no references to memory, and
2521 that any registers modified are dead at the branch site. */
2523 rtx insn, cond, prev;
2524 regset_head merge_set_head, tmp_head, test_live_head, test_set_head;
2525 regset merge_set, tmp, test_live, test_set;
2526 struct propagate_block_info *pbi;
2529 /* Check for no calls or trapping operations. */
2530 for (insn = head; ; insn = NEXT_INSN (insn))
2532 if (GET_CODE (insn) == CALL_INSN)
2536 if (may_trap_p (PATTERN (insn)))
2539 /* ??? Even non-trapping memories such as stack frame
2540 references must be avoided. For stores, we collect
2541 no lifetime info; for reads, we'd have to assert
2542 true_dependence false against every store in the
2544 if (for_each_rtx (&PATTERN (insn), find_memory, NULL))
2551 if (! any_condjump_p (jump))
2554 /* Find the extent of the conditional. */
2555 cond = noce_get_condition (jump, &earliest);
2560 MERGE_SET = set of registers set in MERGE_BB
2561 TEST_LIVE = set of registers live at EARLIEST
2562 TEST_SET = set of registers set between EARLIEST and the
2563 end of the block. */
2565 tmp = INITIALIZE_REG_SET (tmp_head);
2566 merge_set = INITIALIZE_REG_SET (merge_set_head);
2567 test_live = INITIALIZE_REG_SET (test_live_head);
2568 test_set = INITIALIZE_REG_SET (test_set_head);
2570 /* ??? bb->local_set is only valid during calculate_global_regs_live,
2571 so we must recompute usage for MERGE_BB. Not so bad, I suppose,
2572 since we've already asserted that MERGE_BB is small. */
2573 propagate_block (merge_bb, tmp, merge_set, merge_set, 0);
2575 /* For small register class machines, don't lengthen lifetimes of
2576 hard registers before reload. */
2577 if (SMALL_REGISTER_CLASSES && ! reload_completed)
2579 EXECUTE_IF_SET_IN_BITMAP
2582 if (i < FIRST_PSEUDO_REGISTER
2584 && ! global_regs[i])
2589 /* For TEST, we're interested in a range of insns, not a whole block.
2590 Moreover, we're interested in the insns live from OTHER_BB. */
2592 COPY_REG_SET (test_live, other_bb->global_live_at_start);
2593 pbi = init_propagate_block_info (test_bb, test_live, test_set, test_set,
2596 for (insn = jump; ; insn = prev)
2598 prev = propagate_one_insn (pbi, insn);
2599 if (insn == earliest)
2603 free_propagate_block_info (pbi);
2605 /* We can perform the transformation if
2606 MERGE_SET & (TEST_SET | TEST_LIVE)
2608 TEST_SET & merge_bb->global_live_at_start
2611 bitmap_operation (tmp, test_set, test_live, BITMAP_IOR);
2612 bitmap_operation (tmp, tmp, merge_set, BITMAP_AND);
2613 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
2615 bitmap_operation (tmp, test_set, merge_bb->global_live_at_start,
2617 EXECUTE_IF_SET_IN_BITMAP(tmp, 0, i, fail = 1);
2620 FREE_REG_SET (merge_set);
2621 FREE_REG_SET (test_live);
2622 FREE_REG_SET (test_set);
2629 /* We don't want to use normal invert_jump or redirect_jump because
2630 we don't want to delete_insn called. Also, we want to do our own
2631 change group management. */
2633 old_dest = JUMP_LABEL (jump);
2634 if (other_bb != new_dest)
2636 new_label = block_label (new_dest);
2638 ? ! invert_jump_1 (jump, new_label)
2639 : ! redirect_jump_1 (jump, new_label))
2643 if (! apply_change_group ())
2646 if (other_bb != new_dest)
2649 LABEL_NUSES (old_dest) -= 1;
2651 LABEL_NUSES (new_label) += 1;
2652 JUMP_LABEL (jump) = new_label;
2654 invert_br_probabilities (jump);
2656 redirect_edge_succ (BRANCH_EDGE (test_bb), new_dest);
2659 gcov_type count, probability;
2660 count = BRANCH_EDGE (test_bb)->count;
2661 BRANCH_EDGE (test_bb)->count = FALLTHRU_EDGE (test_bb)->count;
2662 FALLTHRU_EDGE (test_bb)->count = count;
2663 probability = BRANCH_EDGE (test_bb)->probability;
2664 BRANCH_EDGE (test_bb)->probability
2665 = FALLTHRU_EDGE (test_bb)->probability;
2666 FALLTHRU_EDGE (test_bb)->probability = probability;
2667 update_br_prob_note (test_bb);
2671 /* Move the insns out of MERGE_BB to before the branch. */
2674 if (end == merge_bb->end)
2675 merge_bb->end = PREV_INSN (head);
2677 if (squeeze_notes (&head, &end))
2680 reorder_insns (head, end, PREV_INSN (earliest));
2683 /* Remove the jump and edge if we can. */
2684 if (other_bb == new_dest)
2687 remove_edge (BRANCH_EDGE (test_bb));
2688 /* ??? Can't merge blocks here, as then_bb is still in use.
2689 At minimum, the merge will get done just before bb-reorder. */
2699 /* Main entry point for all if-conversion. */
2702 if_convert (x_life_data_ok)
2707 num_possible_if_blocks = 0;
2708 num_updated_if_blocks = 0;
2709 num_removed_blocks = 0;
2710 life_data_ok = (x_life_data_ok != 0);
2712 /* Free up basic_block_for_insn so that we don't have to keep it
2713 up to date, either here or in merge_blocks_nomove. */
2714 free_basic_block_vars (1);
2716 /* Compute postdominators if we think we'll use them. */
2717 post_dominators = NULL;
2718 if (HAVE_conditional_execution || life_data_ok)
2720 post_dominators = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
2721 calculate_dominance_info (NULL, post_dominators, CDI_POST_DOMINATORS);
2726 /* Record initial block numbers. */
2727 for (block_num = 0; block_num < n_basic_blocks; block_num++)
2728 SET_ORIG_INDEX (BASIC_BLOCK (block_num), block_num);
2730 /* Go through each of the basic blocks looking for things to convert. */
2731 for (block_num = 0; block_num < n_basic_blocks; )
2733 basic_block bb = BASIC_BLOCK (block_num);
2734 if (find_if_header (bb))
2735 block_num = bb->index;
2740 if (post_dominators)
2741 sbitmap_vector_free (post_dominators);
2744 fflush (rtl_dump_file);
2746 clear_aux_for_blocks ();
2748 /* Rebuild life info for basic blocks that require it. */
2749 if (num_removed_blocks && life_data_ok)
2751 /* If we allocated new pseudos, we must resize the array for sched1. */
2752 if (max_regno < max_reg_num ())
2754 max_regno = max_reg_num ();
2755 allocate_reg_info (max_regno, FALSE, FALSE);
2757 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES,
2758 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2759 | PROP_KILL_DEAD_CODE);
2762 /* Write the final stats. */
2763 if (rtl_dump_file && num_possible_if_blocks > 0)
2765 fprintf (rtl_dump_file,
2766 "\n%d possible IF blocks searched.\n",
2767 num_possible_if_blocks);
2768 fprintf (rtl_dump_file,
2769 "%d IF blocks converted.\n",
2770 num_updated_if_blocks);
2771 fprintf (rtl_dump_file,
2772 "%d basic blocks deleted.\n\n\n",
2773 num_removed_blocks);
2776 #ifdef ENABLE_CHECKING
2777 verify_flow_info ();