1 /* Conditional Dead Call Elimination pass for the GNU compiler.
3 Free Software Foundation, Inc.
4 Contributed by Xinliang David Li <davidxl@google.com>
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it
9 under the terms of the GNU General Public License as published by the
10 Free Software Foundation; either version 3, or (at your option) any
13 GCC is distributed in the hope that it will be useful, but WITHOUT
14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
24 #include "coretypes.h"
28 /* These RTL headers are needed for basic-block.h. */
31 #include "hard-reg-set.h"
33 #include "basic-block.h"
36 #include "diagnostic.h"
37 #include "tree-flow.h"
39 #include "tree-dump.h"
40 #include "tree-pass.h"
45 /* Conditional dead call elimination
47 Some builtin functions can set errno on error conditions, but they
48 are otherwise pure. If the result of a call to such a function is
49 not used, the compiler can still not eliminate the call without
50 powerful interprocedural analysis to prove that the errno is not
51 checked. However, if the conditions under which the error occurs
52 are known, the compiler can conditionally dead code eliminate the
53 calls by shrink-wrapping the semi-dead calls into the error condition:
57 if (error_cond (args))
60 An actual simple example is :
61 log (x); // Mostly dead call
65 With this change, call to log (x) is effectively eliminated, as
66 in majority of the cases, log won't be called with x out of
67 range. The branch is totally predictable, so the branch cost
70 Note that library functions are not supposed to clear errno to zero without
71 error. See IEEE Std 1003.1, section 2.3 Error Numbers, and section 7.5:3 of
74 The condition wrapping the builtin call is conservatively set to avoid too
75 aggressive (wrong) shrink wrapping. The optimization is called conditional
76 dead call elimination because the call is eliminated under the condition
77 that the input arguments would not lead to domain or range error (for
78 instance when x <= 0 for a log (x) call), however the chances that the error
79 condition is hit is very low (those builtin calls which are conditionally
80 dead are usually part of the C++ abstraction penalty exposed after
84 /* A structure for representing input domain of
85 a function argument in integer. If the lower
86 bound is -inf, has_lb is set to false. If the
87 upper bound is +inf, has_ub is false.
88 is_lb_inclusive and is_ub_inclusive are flags
89 to indicate if lb and ub value are inclusive
92 typedef struct input_domain
102 /* A helper function to construct and return an input
103 domain object. LB is the lower bound, HAS_LB is
104 a boolean flag indicating if the lower bound exists,
105 and LB_INCLUSIVE is a boolean flag indicating if the
106 lower bound is inclusive or not. UB, HAS_UB, and
107 UB_INCLUSIVE have the same meaning, but for upper
108 bound of the domain. */
111 get_domain (int lb, bool has_lb, bool lb_inclusive,
112 int ub, bool has_ub, bool ub_inclusive)
116 domain.has_lb = has_lb;
117 domain.is_lb_inclusive = lb_inclusive;
119 domain.has_ub = has_ub;
120 domain.is_ub_inclusive = ub_inclusive;
124 /* A helper function to check the target format for the
125 argument type. In this implementation, only IEEE formats
126 are supported. ARG is the call argument to be checked.
127 Returns true if the format is supported. To support other
128 target formats, function get_no_error_domain needs to be
129 enhanced to have range bounds properly computed. Since
130 the check is cheap (very small number of candidates
131 to be checked), the result is not cached for each float type. */
134 check_target_format (tree arg)
137 enum machine_mode mode;
138 const struct real_format *rfmt;
140 type = TREE_TYPE (arg);
141 mode = TYPE_MODE (type);
142 rfmt = REAL_MODE_FORMAT (mode);
144 && (rfmt == &ieee_single_format || rfmt == &mips_single_format))
146 && (rfmt == &ieee_double_format || rfmt == &mips_double_format))
147 /* For long double, we can not really check XFmode
148 which is only defined on intel platforms.
149 Candidate pre-selection using builtin function
150 code guarantees that we are checking formats
151 for long double modes: double, quad, and extended. */
152 || (mode != SFmode && mode != DFmode
153 && (rfmt == &ieee_quad_format
154 || rfmt == &mips_quad_format
155 || rfmt == &ieee_extended_intel_96_format
156 || rfmt == &ieee_extended_intel_128_format
157 || rfmt == &ieee_extended_intel_96_round_53_format)))
164 /* A helper function to help select calls to pow that are suitable for
165 conditional DCE transformation. It looks for pow calls that can be
166 guided with simple conditions. Such calls either have constant base
167 values or base values converted from integers. Returns true if
168 the pow call POW_CALL is a candidate. */
170 /* The maximum integer bit size for base argument of a pow call
171 that is suitable for shrink-wrapping transformation. */
172 #define MAX_BASE_INT_BIT_SIZE 32
175 check_pow (gimple pow_call)
178 enum tree_code bc, ec;
180 if (gimple_call_num_args (pow_call) != 2)
183 base = gimple_call_arg (pow_call, 0);
184 expn = gimple_call_arg (pow_call, 1);
186 if (!check_target_format (expn))
189 bc = TREE_CODE (base);
190 ec = TREE_CODE (expn);
192 /* Folding candidates are not interesting.
193 Can actually assert that it is already folded. */
194 if (ec == REAL_CST && bc == REAL_CST)
199 /* Only handle a fixed range of constant. */
201 REAL_VALUE_TYPE bcv = TREE_REAL_CST (base);
202 if (REAL_VALUES_EQUAL (bcv, dconst1))
204 if (REAL_VALUES_LESS (bcv, dconst1))
206 real_from_integer (&mv, TYPE_MODE (TREE_TYPE (base)), 256, 0, 1);
207 if (REAL_VALUES_LESS (mv, bcv))
211 else if (bc == SSA_NAME)
213 tree base_val0, base_var, type;
217 /* Only handles cases where base value is converted
218 from integer values. */
219 base_def = SSA_NAME_DEF_STMT (base);
220 if (gimple_code (base_def) != GIMPLE_ASSIGN)
223 if (gimple_assign_rhs_code (base_def) != FLOAT_EXPR)
225 base_val0 = gimple_assign_rhs1 (base_def);
227 base_var = SSA_NAME_VAR (base_val0);
228 if (!DECL_P (base_var))
231 type = TREE_TYPE (base_var);
232 if (TREE_CODE (type) != INTEGER_TYPE)
234 bit_sz = TYPE_PRECISION (type);
235 /* If the type of the base is too wide,
236 the resulting shrink wrapping condition
237 will be too conservative. */
238 if (bit_sz > MAX_BASE_INT_BIT_SIZE)
247 /* A helper function to help select candidate function calls that are
248 suitable for conditional DCE. Candidate functions must have single
249 valid input domain in this implementation except for pow (see check_pow).
250 Returns true if the function call is a candidate. */
253 check_builtin_call (gimple bcall)
257 arg = gimple_call_arg (bcall, 0);
258 return check_target_format (arg);
261 /* A helper function to determine if a builtin function call is a
262 candidate for conditional DCE. Returns true if the builtin call
266 is_call_dce_candidate (gimple call)
269 enum built_in_function fnc;
271 /* Only potentially dead calls are considered. */
272 if (gimple_call_lhs (call))
275 fn = gimple_call_fndecl (call);
277 || !DECL_BUILT_IN (fn)
278 || (DECL_BUILT_IN_CLASS (fn) != BUILT_IN_NORMAL))
281 fnc = DECL_FUNCTION_CODE (fn);
284 /* Trig functions. */
285 CASE_FLT_FN (BUILT_IN_ACOS):
286 CASE_FLT_FN (BUILT_IN_ASIN):
287 /* Hyperbolic functions. */
288 CASE_FLT_FN (BUILT_IN_ACOSH):
289 CASE_FLT_FN (BUILT_IN_ATANH):
290 CASE_FLT_FN (BUILT_IN_COSH):
291 CASE_FLT_FN (BUILT_IN_SINH):
293 CASE_FLT_FN (BUILT_IN_LOG):
294 CASE_FLT_FN (BUILT_IN_LOG2):
295 CASE_FLT_FN (BUILT_IN_LOG10):
296 CASE_FLT_FN (BUILT_IN_LOG1P):
298 CASE_FLT_FN (BUILT_IN_EXP):
299 CASE_FLT_FN (BUILT_IN_EXP2):
300 CASE_FLT_FN (BUILT_IN_EXP10):
301 CASE_FLT_FN (BUILT_IN_EXPM1):
302 CASE_FLT_FN (BUILT_IN_POW10):
304 CASE_FLT_FN (BUILT_IN_SQRT):
305 return check_builtin_call (call);
306 /* Special one: two argument pow. */
308 return check_pow (call);
317 /* A helper function to generate gimple statements for
318 one bound comparison. ARG is the call argument to
319 be compared with the bound, LBUB is the bound value
320 in integer, TCODE is the tree_code of the comparison,
321 TEMP_NAME1/TEMP_NAME2 are names of the temporaries,
322 CONDS is a vector holding the produced GIMPLE statements,
323 and NCONDS points to the variable holding the number
324 of logical comparisons. CONDS is either empty or
325 a list ended with a null tree. */
328 gen_one_condition (tree arg, int lbub,
329 enum tree_code tcode,
330 const char *temp_name1,
331 const char *temp_name2,
332 VEC (gimple, heap) *conds,
335 tree lbub_real_cst, lbub_cst, float_type;
336 tree temp, tempn, tempc, tempcn;
337 gimple stmt1, stmt2, stmt3;
339 float_type = TREE_TYPE (arg);
340 lbub_cst = build_int_cst (integer_type_node, lbub);
341 lbub_real_cst = build_real_from_int_cst (float_type, lbub_cst);
343 temp = create_tmp_var (float_type, temp_name1);
344 stmt1 = gimple_build_assign (temp, arg);
345 tempn = make_ssa_name (temp, stmt1);
346 gimple_assign_set_lhs (stmt1, tempn);
348 tempc = create_tmp_var (boolean_type_node, temp_name2);
349 stmt2 = gimple_build_assign (tempc,
352 tempn, lbub_real_cst));
353 tempcn = make_ssa_name (tempc, stmt2);
354 gimple_assign_set_lhs (stmt2, tempcn);
356 stmt3 = gimple_build_cond_from_tree (tempcn, NULL_TREE, NULL_TREE);
357 VEC_quick_push (gimple, conds, stmt1);
358 VEC_quick_push (gimple, conds, stmt2);
359 VEC_quick_push (gimple, conds, stmt3);
363 /* A helper function to generate GIMPLE statements for
364 out of input domain check. ARG is the call argument
365 to be runtime checked, DOMAIN holds the valid domain
366 for the given function, CONDS points to the vector
367 holding the result GIMPLE statements. *NCONDS is
368 the number of logical comparisons. This function
369 produces no more than two logical comparisons, one
370 for lower bound check, one for upper bound check. */
373 gen_conditions_for_domain (tree arg, inp_domain domain,
374 VEC (gimple, heap) *conds,
378 gen_one_condition (arg, domain.lb,
379 (domain.is_lb_inclusive
380 ? LT_EXPR : LE_EXPR),
381 "DCE_COND_LB", "DCE_COND_LB_TEST",
386 /* Now push a separator. */
388 VEC_quick_push (gimple, conds, NULL);
390 gen_one_condition (arg, domain.ub,
391 (domain.is_ub_inclusive
392 ? GT_EXPR : GE_EXPR),
393 "DCE_COND_UB", "DCE_COND_UB_TEST",
399 /* A helper function to generate condition
400 code for the y argument in call pow (some_const, y).
401 See candidate selection in check_pow. Since the
402 candidates' base values have a limited range,
403 the guarded code generated for y are simple:
406 Note max_y can be computed separately for each
407 const base, but in this implementation, we
408 choose to compute it using the max base
409 in the allowed range for the purpose of
410 simplicity. BASE is the constant base value,
411 EXPN is the expression for the exponent argument,
412 *CONDS is the vector to hold resulting statements,
413 and *NCONDS is the number of logical conditions. */
416 gen_conditions_for_pow_cst_base (tree base, tree expn,
417 VEC (gimple, heap) *conds,
420 inp_domain exp_domain;
421 /* Validate the range of the base constant to make
422 sure it is consistent with check_pow. */
424 REAL_VALUE_TYPE bcv = TREE_REAL_CST (base);
425 gcc_assert (!REAL_VALUES_EQUAL (bcv, dconst1)
426 && !REAL_VALUES_LESS (bcv, dconst1));
427 real_from_integer (&mv, TYPE_MODE (TREE_TYPE (base)), 256, 0, 1);
428 gcc_assert (!REAL_VALUES_LESS (mv, bcv));
430 exp_domain = get_domain (0, false, false,
433 gen_conditions_for_domain (expn, exp_domain,
437 /* Generate error condition code for pow calls with
438 non constant base values. The candidates selected
439 have their base argument value converted from
440 integer (see check_pow) value (1, 2, 4 bytes), and
441 the max exp value is computed based on the size
442 of the integer type (i.e. max possible base value).
443 The resulting input domain for exp argument is thus
444 conservative (smaller than the max value allowed by
445 the runtime value of the base). BASE is the integer
446 base value, EXPN is the expression for the exponent
447 argument, *CONDS is the vector to hold resulting
448 statements, and *NCONDS is the number of logical
452 gen_conditions_for_pow_int_base (tree base, tree expn,
453 VEC (gimple, heap) *conds,
457 tree base_nm, base_val0;
458 tree base_var, int_type;
463 inp_domain exp_domain;
465 base_def = SSA_NAME_DEF_STMT (base);
466 base_nm = gimple_assign_lhs (base_def);
467 base_val0 = gimple_assign_rhs1 (base_def);
468 base_var = SSA_NAME_VAR (base_val0);
469 int_type = TREE_TYPE (base_var);
470 bit_sz = TYPE_PRECISION (int_type);
471 gcc_assert (bit_sz > 0
472 && bit_sz <= MAX_BASE_INT_BIT_SIZE);
474 /* Determine the max exp argument value according to
475 the size of the base integer. The max exp value
476 is conservatively estimated assuming IEEE754 double
480 else if (bit_sz == 16)
484 gcc_assert (bit_sz == MAX_BASE_INT_BIT_SIZE);
488 /* For pow ((double)x, y), generate the following conditions:
495 if (temp2 > max_exp_real_cst) */
497 /* Generate condition in reverse order -- first
498 the condition for the exp argument. */
500 exp_domain = get_domain (0, false, false,
501 max_exp, true, true);
503 gen_conditions_for_domain (expn, exp_domain,
506 /* Now generate condition for the base argument.
507 Note it does not use the helper function
508 gen_conditions_for_domain because the base
511 /* Push a separator. */
512 VEC_quick_push (gimple, conds, NULL);
514 temp = create_tmp_var (int_type, "DCE_COND1");
515 cst0 = build_int_cst (int_type, 0);
516 stmt1 = gimple_build_assign (temp, base_val0);
517 tempn = make_ssa_name (temp, stmt1);
518 gimple_assign_set_lhs (stmt1, tempn);
519 stmt2 = gimple_build_cond (LE_EXPR, tempn, cst0, NULL_TREE, NULL_TREE);
521 VEC_quick_push (gimple, conds, stmt1);
522 VEC_quick_push (gimple, conds, stmt2);
526 /* Method to generate conditional statements for guarding conditionally
527 dead calls to pow. One or more statements can be generated for
528 each logical condition. Statement groups of different conditions
529 are separated by a NULL tree and they are stored in the VEC
530 conds. The number of logical conditions are stored in *nconds.
532 See C99 standard, 7.12.7.4:2, for description of pow (x, y).
533 The precise condition for domain errors are complex. In this
534 implementation, a simplified (but conservative) valid domain
535 for x and y are used: x is positive to avoid dom errors, while
536 y is smaller than a upper bound (depending on x) to avoid range
537 errors. Runtime code is generated to check x (if not constant)
538 and y against the valid domain. If it is out, jump to the call,
539 otherwise the call is bypassed. POW_CALL is the call statement,
540 *CONDS is a vector holding the resulting condition statements,
541 and *NCONDS is the number of logical conditions. */
544 gen_conditions_for_pow (gimple pow_call, VEC (gimple, heap) *conds,
548 enum tree_code bc, ec;
550 #ifdef ENABLE_CHECKING
551 gcc_assert (check_pow (pow_call));
556 base = gimple_call_arg (pow_call, 0);
557 expn = gimple_call_arg (pow_call, 1);
559 bc = TREE_CODE (base);
560 ec = TREE_CODE (expn);
563 gen_conditions_for_pow_cst_base (base, expn, conds, nconds);
564 else if (bc == SSA_NAME)
565 gen_conditions_for_pow_int_base (base, expn, conds, nconds);
570 /* A helper routine to help computing the valid input domain
571 for a builtin function. See C99 7.12.7 for details. In this
572 implementation, we only handle single region domain. The
573 resulting region can be conservative (smaller) than the actual
574 one and rounded to integers. Some of the bounds are documented
575 in the standard, while other limit constants are computed
576 assuming IEEE floating point format (for SF and DF modes).
577 Since IEEE only sets minimum requirements for long double format,
578 different long double formats exist under different implementations
579 (e.g, 64 bit double precision (DF), 80 bit double-extended
580 precision (XF), and 128 bit quad precision (QF) ). For simplicity,
581 in this implementation, the computed bounds for long double assume
582 64 bit format (DF), and are therefore conservative. Another
583 assumption is that single precision float type is always SF mode,
584 and double type is DF mode. This function is quite
585 implementation specific, so it may not be suitable to be part of
586 builtins.c. This needs to be revisited later to see if it can
587 be leveraged in x87 assembly expansion. */
590 get_no_error_domain (enum built_in_function fnc)
594 /* Trig functions: return [-1, +1] */
595 CASE_FLT_FN (BUILT_IN_ACOS):
596 CASE_FLT_FN (BUILT_IN_ASIN):
597 return get_domain (-1, true, true,
599 /* Hyperbolic functions. */
600 CASE_FLT_FN (BUILT_IN_ACOSH):
601 /* acosh: [1, +inf) */
602 return get_domain (1, true, true,
604 CASE_FLT_FN (BUILT_IN_ATANH):
605 /* atanh: (-1, +1) */
606 return get_domain (-1, true, false,
610 /* coshf: (-89, +89) */
611 return get_domain (-89, true, false,
617 /* cosh: (-710, +710) */
618 return get_domain (-710, true, false,
620 /* Log functions: (0, +inf) */
621 CASE_FLT_FN (BUILT_IN_LOG):
622 CASE_FLT_FN (BUILT_IN_LOG2):
623 CASE_FLT_FN (BUILT_IN_LOG10):
624 return get_domain (0, true, false,
626 CASE_FLT_FN (BUILT_IN_LOG1P):
627 return get_domain (-1, true, false,
631 case BUILT_IN_EXPM1F:
632 /* expf: (-inf, 88) */
633 return get_domain (-1, false, false,
638 case BUILT_IN_EXPM1L:
639 /* exp: (-inf, 709) */
640 return get_domain (-1, false, false,
643 /* exp2f: (-inf, 128) */
644 return get_domain (-1, false, false,
648 /* exp2: (-inf, 1024) */
649 return get_domain (-1, false, false,
651 case BUILT_IN_EXP10F:
652 case BUILT_IN_POW10F:
653 /* exp10f: (-inf, 38) */
654 return get_domain (-1, false, false,
658 case BUILT_IN_EXP10L:
659 case BUILT_IN_POW10L:
660 /* exp10: (-inf, 308) */
661 return get_domain (-1, false, false,
663 /* sqrt: [0, +inf) */
664 CASE_FLT_FN (BUILT_IN_SQRT):
665 return get_domain (0, true, true,
674 /* The function to generate shrink wrap conditions for a partially
675 dead builtin call whose return value is not used anywhere,
676 but has to be kept live due to potential error condition.
677 BI_CALL is the builtin call, CONDS is the vector of statements
678 for condition code, NCODES is the pointer to the number of
679 logical conditions. Statements belonging to different logical
680 condition are separated by NULL tree in the vector. */
683 gen_shrink_wrap_conditions (gimple bi_call, VEC (gimple, heap) *conds,
684 unsigned int *nconds)
688 enum built_in_function fnc;
690 gcc_assert (nconds && conds);
691 gcc_assert (VEC_length (gimple, conds) == 0);
692 gcc_assert (is_gimple_call (bi_call));
695 fn = gimple_call_fndecl (call);
696 gcc_assert (fn && DECL_BUILT_IN (fn));
697 fnc = DECL_FUNCTION_CODE (fn);
700 if (fnc == BUILT_IN_POW)
701 gen_conditions_for_pow (call, conds, nconds);
705 inp_domain domain = get_no_error_domain (fnc);
707 arg = gimple_call_arg (bi_call, 0);
708 gen_conditions_for_domain (arg, domain, conds, nconds);
715 /* Probability of the branch (to the call) is taken. */
716 #define ERR_PROB 0.01
718 /* The function to shrink wrap a partially dead builtin call
719 whose return value is not used anywhere, but has to be kept
720 live due to potential error condition. Returns true if the
721 transformation actually happens. */
724 shrink_wrap_one_built_in_call (gimple bi_call)
726 gimple_stmt_iterator bi_call_bsi;
727 basic_block bi_call_bb, join_tgt_bb, guard_bb, guard_bb0;
728 edge join_tgt_in_edge_from_call, join_tgt_in_edge_fall_thru;
729 edge bi_call_in_edge0, guard_bb_in_edge;
730 VEC (gimple, heap) *conds;
731 unsigned tn_cond_stmts, nconds;
733 gimple cond_expr = NULL;
734 gimple cond_expr_start;
735 tree bi_call_label_decl;
736 gimple bi_call_label;
738 conds = VEC_alloc (gimple, heap, 12);
739 gen_shrink_wrap_conditions (bi_call, conds, &nconds);
741 /* This can happen if the condition generator decides
742 it is not beneficial to do the transformation. Just
743 return false and do not do any transformation for
748 bi_call_bb = gimple_bb (bi_call);
750 /* Now find the join target bb -- split
751 bi_call_bb if needed. */
752 bi_call_bsi = gsi_for_stmt (bi_call);
754 join_tgt_in_edge_from_call = split_block (bi_call_bb, bi_call);
755 bi_call_bsi = gsi_for_stmt (bi_call);
757 join_tgt_bb = join_tgt_in_edge_from_call->dest;
759 /* Now it is time to insert the first conditional expression
760 into bi_call_bb and split this bb so that bi_call is
762 tn_cond_stmts = VEC_length (gimple, conds);
764 cond_expr_start = VEC_index (gimple, conds, 0);
765 for (ci = 0; ci < tn_cond_stmts; ci++)
767 gimple c = VEC_index (gimple, conds, ci);
768 gcc_assert (c || ci != 0);
771 gsi_insert_before (&bi_call_bsi, c, GSI_SAME_STMT);
776 gcc_assert (cond_expr && gimple_code (cond_expr) == GIMPLE_COND);
779 bi_call_label_decl = create_artificial_label ();
780 bi_call_label = gimple_build_label (bi_call_label_decl);
781 gsi_insert_before (&bi_call_bsi, bi_call_label, GSI_SAME_STMT);
783 bi_call_in_edge0 = split_block (bi_call_bb, cond_expr);
784 bi_call_in_edge0->flags &= ~EDGE_FALLTHRU;
785 bi_call_in_edge0->flags |= EDGE_TRUE_VALUE;
786 guard_bb0 = bi_call_bb;
787 bi_call_bb = bi_call_in_edge0->dest;
788 join_tgt_in_edge_fall_thru = make_edge (guard_bb0, join_tgt_bb,
791 bi_call_in_edge0->probability = REG_BR_PROB_BASE * ERR_PROB;
792 join_tgt_in_edge_fall_thru->probability =
793 REG_BR_PROB_BASE - bi_call_in_edge0->probability;
795 /* Code generation for the rest of the conditions */
796 guard_bb = guard_bb0;
800 edge bi_call_in_edge;
801 gimple_stmt_iterator guard_bsi = gsi_for_stmt (cond_expr_start);
803 cond_expr_start = VEC_index (gimple, conds, ci0);
804 for (; ci < tn_cond_stmts; ci++)
806 gimple c = VEC_index (gimple, conds, ci);
807 gcc_assert (c || ci != ci0);
810 gsi_insert_before (&guard_bsi, c, GSI_SAME_STMT);
815 gcc_assert (cond_expr && gimple_code (cond_expr) == GIMPLE_COND);
816 guard_bb_in_edge = split_block (guard_bb, cond_expr);
817 guard_bb_in_edge->flags &= ~EDGE_FALLTHRU;
818 guard_bb_in_edge->flags |= EDGE_FALSE_VALUE;
820 bi_call_in_edge = make_edge (guard_bb, bi_call_bb, EDGE_TRUE_VALUE);
822 bi_call_in_edge->probability = REG_BR_PROB_BASE * ERR_PROB;
823 guard_bb_in_edge->probability =
824 REG_BR_PROB_BASE - bi_call_in_edge->probability;
827 VEC_free (gimple, heap, conds);
828 if (dump_file && (dump_flags & TDF_DETAILS))
831 loc = gimple_location (bi_call);
833 "%s:%d: note: function call is shrink-wrapped"
834 " into error conditions.\n",
835 LOCATION_FILE (loc), LOCATION_LINE (loc));
841 /* The top level function for conditional dead code shrink
842 wrapping transformation. */
845 shrink_wrap_conditional_dead_built_in_calls (VEC (gimple, heap) *calls)
847 bool changed = false;
850 unsigned n = VEC_length (gimple, calls);
856 gimple bi_call = VEC_index (gimple, calls, i);
857 changed |= shrink_wrap_one_built_in_call (bi_call);
863 /* Pass entry points. */
866 tree_call_cdce (void)
869 gimple_stmt_iterator i;
870 bool something_changed = false;
871 VEC (gimple, heap) *cond_dead_built_in_calls = NULL;
874 /* Collect dead call candidates. */
875 for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i))
877 gimple stmt = gsi_stmt (i);
878 if (is_gimple_call (stmt)
879 && is_call_dce_candidate (stmt))
881 if (dump_file && (dump_flags & TDF_DETAILS))
883 fprintf (dump_file, "Found conditional dead call: ");
884 print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
885 fprintf (dump_file, "\n");
887 if (cond_dead_built_in_calls == NULL)
888 cond_dead_built_in_calls = VEC_alloc (gimple, heap, 64);
889 VEC_safe_push (gimple, heap, cond_dead_built_in_calls, stmt);
894 if (cond_dead_built_in_calls == NULL)
898 = shrink_wrap_conditional_dead_built_in_calls (cond_dead_built_in_calls);
900 VEC_free (gimple, heap, cond_dead_built_in_calls);
902 if (something_changed)
904 free_dominance_info (CDI_DOMINATORS);
905 free_dominance_info (CDI_POST_DOMINATORS);
906 return (TODO_update_ssa | TODO_cleanup_cfg | TODO_ggc_collect
907 | TODO_remove_unused_locals);
914 gate_call_cdce (void)
916 /* The limit constants used in the implementation
917 assume IEEE floating point format. Other formats
918 can be supported in the future if needed. */
919 return flag_tree_builtin_call_dce != 0 && optimize_function_for_speed_p (cfun);
922 struct gimple_opt_pass pass_call_cdce =
927 gate_call_cdce, /* gate */
928 tree_call_cdce, /* execute */
931 0, /* static_pass_number */
932 TV_TREE_CALL_CDCE, /* tv_id */
933 PROP_cfg | PROP_ssa, /* properties_required */
934 0, /* properties_provided */
935 0, /* properties_destroyed */
936 0, /* todo_flags_start */
937 TODO_dump_func | TODO_verify_ssa /* todo_flags_finish */