1 /* Conditional constant propagation pass for the GNU compiler.
2 Copyright (C) 2000-2015 Free Software Foundation, Inc.
3 Adapted from original RTL SSA-CCP by Daniel Berlin <dberlin@dberlin.org>
4 Adapted to GIMPLE trees by Diego Novillo <dnovillo@redhat.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/>. */
22 /* Conditional constant propagation (CCP) is based on the SSA
23 propagation engine (tree-ssa-propagate.c). Constant assignments of
24 the form VAR = CST are propagated from the assignments into uses of
25 VAR, which in turn may generate new constants. The simulation uses
26 a four level lattice to keep track of constant values associated
27 with SSA names. Given an SSA name V_i, it may take one of the
30 UNINITIALIZED -> the initial state of the value. This value
31 is replaced with a correct initial value
32 the first time the value is used, so the
33 rest of the pass does not need to care about
34 it. Using this value simplifies initialization
35 of the pass, and prevents us from needlessly
36 scanning statements that are never reached.
38 UNDEFINED -> V_i is a local variable whose definition
39 has not been processed yet. Therefore we
40 don't yet know if its value is a constant
43 CONSTANT -> V_i has been found to hold a constant
46 VARYING -> V_i cannot take a constant value, or if it
47 does, it is not possible to determine it
50 The core of SSA-CCP is in ccp_visit_stmt and ccp_visit_phi_node:
52 1- In ccp_visit_stmt, we are interested in assignments whose RHS
53 evaluates into a constant and conditional jumps whose predicate
54 evaluates into a boolean true or false. When an assignment of
55 the form V_i = CONST is found, V_i's lattice value is set to
56 CONSTANT and CONST is associated with it. This causes the
57 propagation engine to add all the SSA edges coming out the
58 assignment into the worklists, so that statements that use V_i
61 If the statement is a conditional with a constant predicate, we
62 mark the outgoing edges as executable or not executable
63 depending on the predicate's value. This is then used when
64 visiting PHI nodes to know when a PHI argument can be ignored.
67 2- In ccp_visit_phi_node, if all the PHI arguments evaluate to the
68 same constant C, then the LHS of the PHI is set to C. This
69 evaluation is known as the "meet operation". Since one of the
70 goals of this evaluation is to optimistically return constant
71 values as often as possible, it uses two main short cuts:
73 - If an argument is flowing in through a non-executable edge, it
74 is ignored. This is useful in cases like this:
80 a_11 = PHI (a_9, a_10)
82 If PRED is known to always evaluate to false, then we can
83 assume that a_11 will always take its value from a_10, meaning
84 that instead of consider it VARYING (a_9 and a_10 have
85 different values), we can consider it CONSTANT 100.
87 - If an argument has an UNDEFINED value, then it does not affect
88 the outcome of the meet operation. If a variable V_i has an
89 UNDEFINED value, it means that either its defining statement
90 hasn't been visited yet or V_i has no defining statement, in
91 which case the original symbol 'V' is being used
92 uninitialized. Since 'V' is a local variable, the compiler
93 may assume any initial value for it.
96 After propagation, every variable V_i that ends up with a lattice
97 value of CONSTANT will have the associated constant value in the
98 array CONST_VAL[i].VALUE. That is fed into substitute_and_fold for
99 final substitution and folding.
101 This algorithm uses wide-ints at the max precision of the target.
102 This means that, with one uninteresting exception, variables with
103 UNSIGNED types never go to VARYING because the bits above the
104 precision of the type of the variable are always zero. The
105 uninteresting case is a variable of UNSIGNED type that has the
106 maximum precision of the target. Such variables can go to VARYING,
107 but this causes no loss of infomation since these variables will
112 Constant propagation with conditional branches,
113 Wegman and Zadeck, ACM TOPLAS 13(2):181-210.
115 Building an Optimizing Compiler,
116 Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9.
118 Advanced Compiler Design and Implementation,
119 Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */
123 #include "coretypes.h"
128 #include "fold-const.h"
129 #include "stor-layout.h"
133 #include "hard-reg-set.h"
134 #include "function.h"
135 #include "dominance.h"
137 #include "basic-block.h"
138 #include "gimple-pretty-print.h"
139 #include "tree-ssa-alias.h"
140 #include "internal-fn.h"
141 #include "gimple-fold.h"
143 #include "gimple-expr.h"
145 #include "gimplify.h"
146 #include "gimple-iterator.h"
147 #include "gimple-ssa.h"
148 #include "tree-cfg.h"
149 #include "tree-phinodes.h"
150 #include "ssa-iterators.h"
151 #include "stringpool.h"
152 #include "tree-ssanames.h"
153 #include "tree-pass.h"
154 #include "tree-ssa-propagate.h"
155 #include "value-prof.h"
156 #include "langhooks.h"
158 #include "diagnostic-core.h"
161 #include "wide-int-print.h"
162 #include "builtins.h"
163 #include "tree-chkp.h"
166 /* Possible lattice values. */
175 struct ccp_prop_value_t
{
177 ccp_lattice_t lattice_val
;
179 /* Propagated value. */
182 /* Mask that applies to the propagated value during CCP. For X
183 with a CONSTANT lattice value X & ~mask == value & ~mask. The
184 zero bits in the mask cover constant values. The ones mean no
189 /* Array of propagated constant values. After propagation,
190 CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If
191 the constant is held in an SSA name representing a memory store
192 (i.e., a VDEF), CONST_VAL[I].MEM_REF will contain the actual
193 memory reference used to store (i.e., the LHS of the assignment
195 static ccp_prop_value_t
*const_val
;
196 static unsigned n_const_val
;
198 static void canonicalize_value (ccp_prop_value_t
*);
199 static bool ccp_fold_stmt (gimple_stmt_iterator
*);
200 static void ccp_lattice_meet (ccp_prop_value_t
*, ccp_prop_value_t
*);
202 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */
205 dump_lattice_value (FILE *outf
, const char *prefix
, ccp_prop_value_t val
)
207 switch (val
.lattice_val
)
210 fprintf (outf
, "%sUNINITIALIZED", prefix
);
213 fprintf (outf
, "%sUNDEFINED", prefix
);
216 fprintf (outf
, "%sVARYING", prefix
);
219 if (TREE_CODE (val
.value
) != INTEGER_CST
222 fprintf (outf
, "%sCONSTANT ", prefix
);
223 print_generic_expr (outf
, val
.value
, dump_flags
);
227 widest_int cval
= wi::bit_and_not (wi::to_widest (val
.value
),
229 fprintf (outf
, "%sCONSTANT ", prefix
);
230 print_hex (cval
, outf
);
231 fprintf (outf
, " (");
232 print_hex (val
.mask
, outf
);
242 /* Print lattice value VAL to stderr. */
244 void debug_lattice_value (ccp_prop_value_t val
);
247 debug_lattice_value (ccp_prop_value_t val
)
249 dump_lattice_value (stderr
, "", val
);
250 fprintf (stderr
, "\n");
253 /* Extend NONZERO_BITS to a full mask, with the upper bits being set. */
256 extend_mask (const wide_int
&nonzero_bits
)
258 return (wi::mask
<widest_int
> (wi::get_precision (nonzero_bits
), true)
259 | widest_int::from (nonzero_bits
, UNSIGNED
));
262 /* Compute a default value for variable VAR and store it in the
263 CONST_VAL array. The following rules are used to get default
266 1- Global and static variables that are declared constant are
269 2- Any other value is considered UNDEFINED. This is useful when
270 considering PHI nodes. PHI arguments that are undefined do not
271 change the constant value of the PHI node, which allows for more
272 constants to be propagated.
274 3- Variables defined by statements other than assignments and PHI
275 nodes are considered VARYING.
277 4- Initial values of variables that are not GIMPLE registers are
278 considered VARYING. */
280 static ccp_prop_value_t
281 get_default_value (tree var
)
283 ccp_prop_value_t val
= { UNINITIALIZED
, NULL_TREE
, 0 };
286 stmt
= SSA_NAME_DEF_STMT (var
);
288 if (gimple_nop_p (stmt
))
290 /* Variables defined by an empty statement are those used
291 before being initialized. If VAR is a local variable, we
292 can assume initially that it is UNDEFINED, otherwise we must
293 consider it VARYING. */
294 if (!virtual_operand_p (var
)
295 && TREE_CODE (SSA_NAME_VAR (var
)) == VAR_DECL
)
296 val
.lattice_val
= UNDEFINED
;
299 val
.lattice_val
= VARYING
;
301 if (flag_tree_bit_ccp
)
303 wide_int nonzero_bits
= get_nonzero_bits (var
);
304 if (nonzero_bits
!= -1)
306 val
.lattice_val
= CONSTANT
;
307 val
.value
= build_zero_cst (TREE_TYPE (var
));
308 val
.mask
= extend_mask (nonzero_bits
);
313 else if (is_gimple_assign (stmt
))
316 if (gimple_assign_single_p (stmt
)
317 && DECL_P (gimple_assign_rhs1 (stmt
))
318 && (cst
= get_symbol_constant_value (gimple_assign_rhs1 (stmt
))))
320 val
.lattice_val
= CONSTANT
;
325 /* Any other variable defined by an assignment is considered
327 val
.lattice_val
= UNDEFINED
;
330 else if ((is_gimple_call (stmt
)
331 && gimple_call_lhs (stmt
) != NULL_TREE
)
332 || gimple_code (stmt
) == GIMPLE_PHI
)
334 /* A variable defined by a call or a PHI node is considered
336 val
.lattice_val
= UNDEFINED
;
340 /* Otherwise, VAR will never take on a constant value. */
341 val
.lattice_val
= VARYING
;
349 /* Get the constant value associated with variable VAR. */
351 static inline ccp_prop_value_t
*
354 ccp_prop_value_t
*val
;
356 if (const_val
== NULL
357 || SSA_NAME_VERSION (var
) >= n_const_val
)
360 val
= &const_val
[SSA_NAME_VERSION (var
)];
361 if (val
->lattice_val
== UNINITIALIZED
)
362 *val
= get_default_value (var
);
364 canonicalize_value (val
);
369 /* Return the constant tree value associated with VAR. */
372 get_constant_value (tree var
)
374 ccp_prop_value_t
*val
;
375 if (TREE_CODE (var
) != SSA_NAME
)
377 if (is_gimple_min_invariant (var
))
381 val
= get_value (var
);
383 && val
->lattice_val
== CONSTANT
384 && (TREE_CODE (val
->value
) != INTEGER_CST
390 /* Sets the value associated with VAR to VARYING. */
393 set_value_varying (tree var
)
395 ccp_prop_value_t
*val
= &const_val
[SSA_NAME_VERSION (var
)];
397 val
->lattice_val
= VARYING
;
398 val
->value
= NULL_TREE
;
402 /* For integer constants, make sure to drop TREE_OVERFLOW. */
405 canonicalize_value (ccp_prop_value_t
*val
)
407 if (val
->lattice_val
!= CONSTANT
)
410 if (TREE_OVERFLOW_P (val
->value
))
411 val
->value
= drop_tree_overflow (val
->value
);
414 /* Return whether the lattice transition is valid. */
417 valid_lattice_transition (ccp_prop_value_t old_val
, ccp_prop_value_t new_val
)
419 /* Lattice transitions must always be monotonically increasing in
421 if (old_val
.lattice_val
< new_val
.lattice_val
)
424 if (old_val
.lattice_val
!= new_val
.lattice_val
)
427 if (!old_val
.value
&& !new_val
.value
)
430 /* Now both lattice values are CONSTANT. */
432 /* Allow arbitrary copy changes as we might look through PHI <a_1, ...>
433 when only a single copy edge is executable. */
434 if (TREE_CODE (old_val
.value
) == SSA_NAME
435 && TREE_CODE (new_val
.value
) == SSA_NAME
)
438 /* Allow transitioning from a constant to a copy. */
439 if (is_gimple_min_invariant (old_val
.value
)
440 && TREE_CODE (new_val
.value
) == SSA_NAME
)
443 /* Allow transitioning from PHI <&x, not executable> == &x
444 to PHI <&x, &y> == common alignment. */
445 if (TREE_CODE (old_val
.value
) != INTEGER_CST
446 && TREE_CODE (new_val
.value
) == INTEGER_CST
)
449 /* Bit-lattices have to agree in the still valid bits. */
450 if (TREE_CODE (old_val
.value
) == INTEGER_CST
451 && TREE_CODE (new_val
.value
) == INTEGER_CST
)
452 return (wi::bit_and_not (wi::to_widest (old_val
.value
), new_val
.mask
)
453 == wi::bit_and_not (wi::to_widest (new_val
.value
), new_val
.mask
));
455 /* Otherwise constant values have to agree. */
456 if (operand_equal_p (old_val
.value
, new_val
.value
, 0))
459 /* At least the kinds and types should agree now. */
460 if (TREE_CODE (old_val
.value
) != TREE_CODE (new_val
.value
)
461 || !types_compatible_p (TREE_TYPE (old_val
.value
),
462 TREE_TYPE (new_val
.value
)))
465 /* For floats and !HONOR_NANS allow transitions from (partial) NaN
467 tree type
= TREE_TYPE (new_val
.value
);
468 if (SCALAR_FLOAT_TYPE_P (type
)
469 && !HONOR_NANS (type
))
471 if (REAL_VALUE_ISNAN (TREE_REAL_CST (old_val
.value
)))
474 else if (VECTOR_FLOAT_TYPE_P (type
)
475 && !HONOR_NANS (type
))
477 for (unsigned i
= 0; i
< VECTOR_CST_NELTS (old_val
.value
); ++i
)
478 if (!REAL_VALUE_ISNAN
479 (TREE_REAL_CST (VECTOR_CST_ELT (old_val
.value
, i
)))
480 && !operand_equal_p (VECTOR_CST_ELT (old_val
.value
, i
),
481 VECTOR_CST_ELT (new_val
.value
, i
), 0))
485 else if (COMPLEX_FLOAT_TYPE_P (type
)
486 && !HONOR_NANS (type
))
488 if (!REAL_VALUE_ISNAN (TREE_REAL_CST (TREE_REALPART (old_val
.value
)))
489 && !operand_equal_p (TREE_REALPART (old_val
.value
),
490 TREE_REALPART (new_val
.value
), 0))
492 if (!REAL_VALUE_ISNAN (TREE_REAL_CST (TREE_IMAGPART (old_val
.value
)))
493 && !operand_equal_p (TREE_IMAGPART (old_val
.value
),
494 TREE_IMAGPART (new_val
.value
), 0))
501 /* Set the value for variable VAR to NEW_VAL. Return true if the new
502 value is different from VAR's previous value. */
505 set_lattice_value (tree var
, ccp_prop_value_t
*new_val
)
507 /* We can deal with old UNINITIALIZED values just fine here. */
508 ccp_prop_value_t
*old_val
= &const_val
[SSA_NAME_VERSION (var
)];
510 canonicalize_value (new_val
);
512 /* We have to be careful to not go up the bitwise lattice
513 represented by the mask. Instead of dropping to VARYING
514 use the meet operator to retain a conservative value.
515 Missed optimizations like PR65851 makes this necessary.
516 It also ensures we converge to a stable lattice solution. */
517 if (new_val
->lattice_val
== CONSTANT
518 && old_val
->lattice_val
== CONSTANT
519 && TREE_CODE (new_val
->value
) != SSA_NAME
)
520 ccp_lattice_meet (new_val
, old_val
);
522 gcc_checking_assert (valid_lattice_transition (*old_val
, *new_val
));
524 /* If *OLD_VAL and NEW_VAL are the same, return false to inform the
525 caller that this was a non-transition. */
526 if (old_val
->lattice_val
!= new_val
->lattice_val
527 || (new_val
->lattice_val
== CONSTANT
528 && (TREE_CODE (new_val
->value
) != TREE_CODE (old_val
->value
)
529 || (TREE_CODE (new_val
->value
) == INTEGER_CST
530 && (new_val
->mask
!= old_val
->mask
531 || (wi::bit_and_not (wi::to_widest (old_val
->value
),
533 != wi::bit_and_not (wi::to_widest (new_val
->value
),
535 || (TREE_CODE (new_val
->value
) != INTEGER_CST
536 && !operand_equal_p (new_val
->value
, old_val
->value
, 0)))))
538 /* ??? We would like to delay creation of INTEGER_CSTs from
539 partially constants here. */
541 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
543 dump_lattice_value (dump_file
, "Lattice value changed to ", *new_val
);
544 fprintf (dump_file
, ". Adding SSA edges to worklist.\n");
549 gcc_assert (new_val
->lattice_val
!= UNINITIALIZED
);
556 static ccp_prop_value_t
get_value_for_expr (tree
, bool);
557 static ccp_prop_value_t
bit_value_binop (enum tree_code
, tree
, tree
, tree
);
558 static void bit_value_binop_1 (enum tree_code
, tree
, widest_int
*, widest_int
*,
559 tree
, const widest_int
&, const widest_int
&,
560 tree
, const widest_int
&, const widest_int
&);
562 /* Return a widest_int that can be used for bitwise simplifications
566 value_to_wide_int (ccp_prop_value_t val
)
569 && TREE_CODE (val
.value
) == INTEGER_CST
)
570 return wi::to_widest (val
.value
);
575 /* Return the value for the address expression EXPR based on alignment
578 static ccp_prop_value_t
579 get_value_from_alignment (tree expr
)
581 tree type
= TREE_TYPE (expr
);
582 ccp_prop_value_t val
;
583 unsigned HOST_WIDE_INT bitpos
;
586 gcc_assert (TREE_CODE (expr
) == ADDR_EXPR
);
588 get_pointer_alignment_1 (expr
, &align
, &bitpos
);
589 val
.mask
= (POINTER_TYPE_P (type
) || TYPE_UNSIGNED (type
)
590 ? wi::mask
<widest_int
> (TYPE_PRECISION (type
), false)
591 : -1).and_not (align
/ BITS_PER_UNIT
- 1);
593 = wi::sext (val
.mask
, TYPE_PRECISION (type
)) == -1 ? VARYING
: CONSTANT
;
594 if (val
.lattice_val
== CONSTANT
)
595 val
.value
= build_int_cstu (type
, bitpos
/ BITS_PER_UNIT
);
597 val
.value
= NULL_TREE
;
602 /* Return the value for the tree operand EXPR. If FOR_BITS_P is true
603 return constant bits extracted from alignment information for
604 invariant addresses. */
606 static ccp_prop_value_t
607 get_value_for_expr (tree expr
, bool for_bits_p
)
609 ccp_prop_value_t val
;
611 if (TREE_CODE (expr
) == SSA_NAME
)
613 val
= *get_value (expr
);
615 && val
.lattice_val
== CONSTANT
616 && TREE_CODE (val
.value
) == ADDR_EXPR
)
617 val
= get_value_from_alignment (val
.value
);
618 /* Fall back to a copy value. */
620 && val
.lattice_val
== VARYING
621 && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (expr
))
623 val
.lattice_val
= CONSTANT
;
628 else if (is_gimple_min_invariant (expr
)
629 && (!for_bits_p
|| TREE_CODE (expr
) != ADDR_EXPR
))
631 val
.lattice_val
= CONSTANT
;
634 canonicalize_value (&val
);
636 else if (TREE_CODE (expr
) == ADDR_EXPR
)
637 val
= get_value_from_alignment (expr
);
640 val
.lattice_val
= VARYING
;
642 val
.value
= NULL_TREE
;
647 /* Return the likely CCP lattice value for STMT.
649 If STMT has no operands, then return CONSTANT.
651 Else if undefinedness of operands of STMT cause its value to be
652 undefined, then return UNDEFINED.
654 Else if any operands of STMT are constants, then return CONSTANT.
656 Else return VARYING. */
659 likely_value (gimple stmt
)
661 bool has_constant_operand
, has_undefined_operand
, all_undefined_operands
;
662 bool has_nsa_operand
;
667 enum gimple_code code
= gimple_code (stmt
);
669 /* This function appears to be called only for assignments, calls,
670 conditionals, and switches, due to the logic in visit_stmt. */
671 gcc_assert (code
== GIMPLE_ASSIGN
672 || code
== GIMPLE_CALL
673 || code
== GIMPLE_COND
674 || code
== GIMPLE_SWITCH
);
676 /* If the statement has volatile operands, it won't fold to a
678 if (gimple_has_volatile_ops (stmt
))
681 /* Arrive here for more complex cases. */
682 has_constant_operand
= false;
683 has_undefined_operand
= false;
684 all_undefined_operands
= true;
685 has_nsa_operand
= false;
686 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, iter
, SSA_OP_USE
)
688 ccp_prop_value_t
*val
= get_value (use
);
690 if (val
->lattice_val
== UNDEFINED
)
691 has_undefined_operand
= true;
693 all_undefined_operands
= false;
695 if (val
->lattice_val
== CONSTANT
)
696 has_constant_operand
= true;
698 if (SSA_NAME_IS_DEFAULT_DEF (use
)
699 || !prop_simulate_again_p (SSA_NAME_DEF_STMT (use
)))
700 has_nsa_operand
= true;
703 /* There may be constants in regular rhs operands. For calls we
704 have to ignore lhs, fndecl and static chain, otherwise only
706 for (i
= (is_gimple_call (stmt
) ? 2 : 0) + gimple_has_lhs (stmt
);
707 i
< gimple_num_ops (stmt
); ++i
)
709 tree op
= gimple_op (stmt
, i
);
710 if (!op
|| TREE_CODE (op
) == SSA_NAME
)
712 if (is_gimple_min_invariant (op
))
713 has_constant_operand
= true;
716 if (has_constant_operand
)
717 all_undefined_operands
= false;
719 if (has_undefined_operand
720 && code
== GIMPLE_CALL
721 && gimple_call_internal_p (stmt
))
722 switch (gimple_call_internal_fn (stmt
))
724 /* These 3 builtins use the first argument just as a magic
725 way how to find out a decl uid. */
726 case IFN_GOMP_SIMD_LANE
:
727 case IFN_GOMP_SIMD_VF
:
728 case IFN_GOMP_SIMD_LAST_LANE
:
729 has_undefined_operand
= false;
735 /* If the operation combines operands like COMPLEX_EXPR make sure to
736 not mark the result UNDEFINED if only one part of the result is
738 if (has_undefined_operand
&& all_undefined_operands
)
740 else if (code
== GIMPLE_ASSIGN
&& has_undefined_operand
)
742 switch (gimple_assign_rhs_code (stmt
))
744 /* Unary operators are handled with all_undefined_operands. */
747 case POINTER_PLUS_EXPR
:
748 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected.
749 Not bitwise operators, one VARYING operand may specify the
750 result completely. Not logical operators for the same reason.
751 Not COMPLEX_EXPR as one VARYING operand makes the result partly
752 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because
753 the undefined operand may be promoted. */
757 /* If any part of an address is UNDEFINED, like the index
758 of an ARRAY_EXPR, then treat the result as UNDEFINED. */
765 /* If there was an UNDEFINED operand but the result may be not UNDEFINED
766 fall back to CONSTANT. During iteration UNDEFINED may still drop
768 if (has_undefined_operand
)
771 /* We do not consider virtual operands here -- load from read-only
772 memory may have only VARYING virtual operands, but still be
773 constant. Also we can combine the stmt with definitions from
774 operands whose definitions are not simulated again. */
775 if (has_constant_operand
777 || gimple_references_memory_p (stmt
))
783 /* Returns true if STMT cannot be constant. */
786 surely_varying_stmt_p (gimple stmt
)
788 /* If the statement has operands that we cannot handle, it cannot be
790 if (gimple_has_volatile_ops (stmt
))
793 /* If it is a call and does not return a value or is not a
794 builtin and not an indirect call or a call to function with
795 assume_aligned/alloc_align attribute, it is varying. */
796 if (is_gimple_call (stmt
))
798 tree fndecl
, fntype
= gimple_call_fntype (stmt
);
799 if (!gimple_call_lhs (stmt
)
800 || ((fndecl
= gimple_call_fndecl (stmt
)) != NULL_TREE
801 && !DECL_BUILT_IN (fndecl
)
802 && !lookup_attribute ("assume_aligned",
803 TYPE_ATTRIBUTES (fntype
))
804 && !lookup_attribute ("alloc_align",
805 TYPE_ATTRIBUTES (fntype
))))
809 /* Any other store operation is not interesting. */
810 else if (gimple_vdef (stmt
))
813 /* Anything other than assignments and conditional jumps are not
814 interesting for CCP. */
815 if (gimple_code (stmt
) != GIMPLE_ASSIGN
816 && gimple_code (stmt
) != GIMPLE_COND
817 && gimple_code (stmt
) != GIMPLE_SWITCH
818 && gimple_code (stmt
) != GIMPLE_CALL
)
824 /* Initialize local data structures for CCP. */
827 ccp_initialize (void)
831 n_const_val
= num_ssa_names
;
832 const_val
= XCNEWVEC (ccp_prop_value_t
, n_const_val
);
834 /* Initialize simulation flags for PHI nodes and statements. */
835 FOR_EACH_BB_FN (bb
, cfun
)
837 gimple_stmt_iterator i
;
839 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); gsi_next (&i
))
841 gimple stmt
= gsi_stmt (i
);
844 /* If the statement is a control insn, then we do not
845 want to avoid simulating the statement once. Failure
846 to do so means that those edges will never get added. */
847 if (stmt_ends_bb_p (stmt
))
850 is_varying
= surely_varying_stmt_p (stmt
);
857 /* If the statement will not produce a constant, mark
858 all its outputs VARYING. */
859 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
860 set_value_varying (def
);
862 prop_set_simulate_again (stmt
, !is_varying
);
866 /* Now process PHI nodes. We never clear the simulate_again flag on
867 phi nodes, since we do not know which edges are executable yet,
868 except for phi nodes for virtual operands when we do not do store ccp. */
869 FOR_EACH_BB_FN (bb
, cfun
)
873 for (i
= gsi_start_phis (bb
); !gsi_end_p (i
); gsi_next (&i
))
875 gphi
*phi
= i
.phi ();
877 if (virtual_operand_p (gimple_phi_result (phi
)))
878 prop_set_simulate_again (phi
, false);
880 prop_set_simulate_again (phi
, true);
885 /* Debug count support. Reset the values of ssa names
886 VARYING when the total number ssa names analyzed is
887 beyond the debug count specified. */
893 for (i
= 0; i
< num_ssa_names
; i
++)
897 const_val
[i
].lattice_val
= VARYING
;
898 const_val
[i
].mask
= -1;
899 const_val
[i
].value
= NULL_TREE
;
905 /* Do final substitution of propagated values, cleanup the flowgraph and
906 free allocated storage.
908 Return TRUE when something was optimized. */
913 bool something_changed
;
918 /* Derive alignment and misalignment information from partially
919 constant pointers in the lattice or nonzero bits from partially
920 constant integers. */
921 for (i
= 1; i
< num_ssa_names
; ++i
)
923 tree name
= ssa_name (i
);
924 ccp_prop_value_t
*val
;
925 unsigned int tem
, align
;
928 || (!POINTER_TYPE_P (TREE_TYPE (name
))
929 && (!INTEGRAL_TYPE_P (TREE_TYPE (name
))
930 /* Don't record nonzero bits before IPA to avoid
931 using too much memory. */
932 || first_pass_instance
)))
935 val
= get_value (name
);
936 if (val
->lattice_val
!= CONSTANT
937 || TREE_CODE (val
->value
) != INTEGER_CST
)
940 if (POINTER_TYPE_P (TREE_TYPE (name
)))
942 /* Trailing mask bits specify the alignment, trailing value
943 bits the misalignment. */
944 tem
= val
->mask
.to_uhwi ();
945 align
= (tem
& -tem
);
947 set_ptr_info_alignment (get_ptr_info (name
), align
,
948 (TREE_INT_CST_LOW (val
->value
)
953 unsigned int precision
= TYPE_PRECISION (TREE_TYPE (val
->value
));
954 wide_int nonzero_bits
= wide_int::from (val
->mask
, precision
,
955 UNSIGNED
) | val
->value
;
956 nonzero_bits
&= get_nonzero_bits (name
);
957 set_nonzero_bits (name
, nonzero_bits
);
961 /* Perform substitutions based on the known constant values. */
962 something_changed
= substitute_and_fold (get_constant_value
,
963 ccp_fold_stmt
, true);
967 return something_changed
;;
971 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
974 any M UNDEFINED = any
975 any M VARYING = VARYING
976 Ci M Cj = Ci if (i == j)
977 Ci M Cj = VARYING if (i != j)
981 ccp_lattice_meet (ccp_prop_value_t
*val1
, ccp_prop_value_t
*val2
)
983 if (val1
->lattice_val
== UNDEFINED
984 /* For UNDEFINED M SSA we can't always SSA because its definition
985 may not dominate the PHI node. Doing optimistic copy propagation
986 also causes a lot of gcc.dg/uninit-pred*.c FAILs. */
987 && (val2
->lattice_val
!= CONSTANT
988 || TREE_CODE (val2
->value
) != SSA_NAME
))
990 /* UNDEFINED M any = any */
993 else if (val2
->lattice_val
== UNDEFINED
995 && (val1
->lattice_val
!= CONSTANT
996 || TREE_CODE (val1
->value
) != SSA_NAME
))
998 /* any M UNDEFINED = any
999 Nothing to do. VAL1 already contains the value we want. */
1002 else if (val1
->lattice_val
== VARYING
1003 || val2
->lattice_val
== VARYING
)
1005 /* any M VARYING = VARYING. */
1006 val1
->lattice_val
= VARYING
;
1008 val1
->value
= NULL_TREE
;
1010 else if (val1
->lattice_val
== CONSTANT
1011 && val2
->lattice_val
== CONSTANT
1012 && TREE_CODE (val1
->value
) == INTEGER_CST
1013 && TREE_CODE (val2
->value
) == INTEGER_CST
)
1015 /* Ci M Cj = Ci if (i == j)
1016 Ci M Cj = VARYING if (i != j)
1018 For INTEGER_CSTs mask unequal bits. If no equal bits remain,
1020 val1
->mask
= (val1
->mask
| val2
->mask
1021 | (wi::to_widest (val1
->value
)
1022 ^ wi::to_widest (val2
->value
)));
1023 if (wi::sext (val1
->mask
, TYPE_PRECISION (TREE_TYPE (val1
->value
))) == -1)
1025 val1
->lattice_val
= VARYING
;
1026 val1
->value
= NULL_TREE
;
1029 else if (val1
->lattice_val
== CONSTANT
1030 && val2
->lattice_val
== CONSTANT
1031 && operand_equal_p (val1
->value
, val2
->value
, 0))
1033 /* Ci M Cj = Ci if (i == j)
1034 Ci M Cj = VARYING if (i != j)
1036 VAL1 already contains the value we want for equivalent values. */
1038 else if (val1
->lattice_val
== CONSTANT
1039 && val2
->lattice_val
== CONSTANT
1040 && (TREE_CODE (val1
->value
) == ADDR_EXPR
1041 || TREE_CODE (val2
->value
) == ADDR_EXPR
))
1043 /* When not equal addresses are involved try meeting for
1045 ccp_prop_value_t tem
= *val2
;
1046 if (TREE_CODE (val1
->value
) == ADDR_EXPR
)
1047 *val1
= get_value_for_expr (val1
->value
, true);
1048 if (TREE_CODE (val2
->value
) == ADDR_EXPR
)
1049 tem
= get_value_for_expr (val2
->value
, true);
1050 ccp_lattice_meet (val1
, &tem
);
1054 /* Any other combination is VARYING. */
1055 val1
->lattice_val
= VARYING
;
1057 val1
->value
= NULL_TREE
;
1062 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
1063 lattice values to determine PHI_NODE's lattice value. The value of a
1064 PHI node is determined calling ccp_lattice_meet with all the arguments
1065 of the PHI node that are incoming via executable edges. */
1067 static enum ssa_prop_result
1068 ccp_visit_phi_node (gphi
*phi
)
1071 ccp_prop_value_t new_val
;
1073 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1075 fprintf (dump_file
, "\nVisiting PHI node: ");
1076 print_gimple_stmt (dump_file
, phi
, 0, dump_flags
);
1079 new_val
.lattice_val
= UNDEFINED
;
1080 new_val
.value
= NULL_TREE
;
1084 bool non_exec_edge
= false;
1085 for (i
= 0; i
< gimple_phi_num_args (phi
); i
++)
1087 /* Compute the meet operator over all the PHI arguments flowing
1088 through executable edges. */
1089 edge e
= gimple_phi_arg_edge (phi
, i
);
1091 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1094 "\n Argument #%d (%d -> %d %sexecutable)\n",
1095 i
, e
->src
->index
, e
->dest
->index
,
1096 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
1099 /* If the incoming edge is executable, Compute the meet operator for
1100 the existing value of the PHI node and the current PHI argument. */
1101 if (e
->flags
& EDGE_EXECUTABLE
)
1103 tree arg
= gimple_phi_arg (phi
, i
)->def
;
1104 ccp_prop_value_t arg_val
= get_value_for_expr (arg
, false);
1112 ccp_lattice_meet (&new_val
, &arg_val
);
1114 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1116 fprintf (dump_file
, "\t");
1117 print_generic_expr (dump_file
, arg
, dump_flags
);
1118 dump_lattice_value (dump_file
, "\tValue: ", arg_val
);
1119 fprintf (dump_file
, "\n");
1122 if (new_val
.lattice_val
== VARYING
)
1126 non_exec_edge
= true;
1129 /* In case there were non-executable edges and the value is a copy
1130 make sure its definition dominates the PHI node. */
1132 && new_val
.lattice_val
== CONSTANT
1133 && TREE_CODE (new_val
.value
) == SSA_NAME
1134 && ! SSA_NAME_IS_DEFAULT_DEF (new_val
.value
)
1135 && ! dominated_by_p (CDI_DOMINATORS
, gimple_bb (phi
),
1136 gimple_bb (SSA_NAME_DEF_STMT (new_val
.value
))))
1138 new_val
.lattice_val
= VARYING
;
1139 new_val
.value
= NULL_TREE
;
1143 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1145 dump_lattice_value (dump_file
, "\n PHI node value: ", new_val
);
1146 fprintf (dump_file
, "\n\n");
1149 /* Make the transition to the new value. */
1150 if (set_lattice_value (gimple_phi_result (phi
), &new_val
))
1152 if (new_val
.lattice_val
== VARYING
)
1153 return SSA_PROP_VARYING
;
1155 return SSA_PROP_INTERESTING
;
1158 return SSA_PROP_NOT_INTERESTING
;
1161 /* Return the constant value for OP or OP otherwise. */
1164 valueize_op (tree op
)
1166 if (TREE_CODE (op
) == SSA_NAME
)
1168 tree tem
= get_constant_value (op
);
1175 /* Return the constant value for OP, but signal to not follow SSA
1176 edges if the definition may be simulated again. */
1179 valueize_op_1 (tree op
)
1181 if (TREE_CODE (op
) == SSA_NAME
)
1183 /* If the definition may be simulated again we cannot follow
1184 this SSA edge as the SSA propagator does not necessarily
1185 re-visit the use. */
1186 gimple def_stmt
= SSA_NAME_DEF_STMT (op
);
1187 if (!gimple_nop_p (def_stmt
)
1188 && prop_simulate_again_p (def_stmt
))
1190 tree tem
= get_constant_value (op
);
1197 /* CCP specific front-end to the non-destructive constant folding
1200 Attempt to simplify the RHS of STMT knowing that one or more
1201 operands are constants.
1203 If simplification is possible, return the simplified RHS,
1204 otherwise return the original RHS or NULL_TREE. */
1207 ccp_fold (gimple stmt
)
1209 location_t loc
= gimple_location (stmt
);
1210 switch (gimple_code (stmt
))
1214 /* Handle comparison operators that can appear in GIMPLE form. */
1215 tree op0
= valueize_op (gimple_cond_lhs (stmt
));
1216 tree op1
= valueize_op (gimple_cond_rhs (stmt
));
1217 enum tree_code code
= gimple_cond_code (stmt
);
1218 return fold_binary_loc (loc
, code
, boolean_type_node
, op0
, op1
);
1223 /* Return the constant switch index. */
1224 return valueize_op (gimple_switch_index (as_a
<gswitch
*> (stmt
)));
1229 return gimple_fold_stmt_to_constant_1 (stmt
,
1230 valueize_op
, valueize_op_1
);
1237 /* Apply the operation CODE in type TYPE to the value, mask pair
1238 RVAL and RMASK representing a value of type RTYPE and set
1239 the value, mask pair *VAL and *MASK to the result. */
1242 bit_value_unop_1 (enum tree_code code
, tree type
,
1243 widest_int
*val
, widest_int
*mask
,
1244 tree rtype
, const widest_int
&rval
, const widest_int
&rmask
)
1255 widest_int temv
, temm
;
1256 /* Return ~rval + 1. */
1257 bit_value_unop_1 (BIT_NOT_EXPR
, type
, &temv
, &temm
, type
, rval
, rmask
);
1258 bit_value_binop_1 (PLUS_EXPR
, type
, val
, mask
,
1259 type
, temv
, temm
, type
, 1, 0);
1267 /* First extend mask and value according to the original type. */
1268 sgn
= TYPE_SIGN (rtype
);
1269 *mask
= wi::ext (rmask
, TYPE_PRECISION (rtype
), sgn
);
1270 *val
= wi::ext (rval
, TYPE_PRECISION (rtype
), sgn
);
1272 /* Then extend mask and value according to the target type. */
1273 sgn
= TYPE_SIGN (type
);
1274 *mask
= wi::ext (*mask
, TYPE_PRECISION (type
), sgn
);
1275 *val
= wi::ext (*val
, TYPE_PRECISION (type
), sgn
);
1285 /* Apply the operation CODE in type TYPE to the value, mask pairs
1286 R1VAL, R1MASK and R2VAL, R2MASK representing a values of type R1TYPE
1287 and R2TYPE and set the value, mask pair *VAL and *MASK to the result. */
1290 bit_value_binop_1 (enum tree_code code
, tree type
,
1291 widest_int
*val
, widest_int
*mask
,
1292 tree r1type
, const widest_int
&r1val
,
1293 const widest_int
&r1mask
, tree r2type
,
1294 const widest_int
&r2val
, const widest_int
&r2mask
)
1296 signop sgn
= TYPE_SIGN (type
);
1297 int width
= TYPE_PRECISION (type
);
1298 bool swap_p
= false;
1300 /* Assume we'll get a constant result. Use an initial non varying
1301 value, we fall back to varying in the end if necessary. */
1307 /* The mask is constant where there is a known not
1308 set bit, (m1 | m2) & ((v1 | m1) & (v2 | m2)) */
1309 *mask
= (r1mask
| r2mask
) & (r1val
| r1mask
) & (r2val
| r2mask
);
1310 *val
= r1val
& r2val
;
1314 /* The mask is constant where there is a known
1315 set bit, (m1 | m2) & ~((v1 & ~m1) | (v2 & ~m2)). */
1316 *mask
= (r1mask
| r2mask
)
1317 .and_not (r1val
.and_not (r1mask
) | r2val
.and_not (r2mask
));
1318 *val
= r1val
| r2val
;
1323 *mask
= r1mask
| r2mask
;
1324 *val
= r1val
^ r2val
;
1331 widest_int shift
= r2val
;
1339 if (wi::neg_p (shift
))
1342 if (code
== RROTATE_EXPR
)
1343 code
= LROTATE_EXPR
;
1345 code
= RROTATE_EXPR
;
1347 if (code
== RROTATE_EXPR
)
1349 *mask
= wi::rrotate (r1mask
, shift
, width
);
1350 *val
= wi::rrotate (r1val
, shift
, width
);
1354 *mask
= wi::lrotate (r1mask
, shift
, width
);
1355 *val
= wi::lrotate (r1val
, shift
, width
);
1363 /* ??? We can handle partially known shift counts if we know
1364 its sign. That way we can tell that (x << (y | 8)) & 255
1368 widest_int shift
= r2val
;
1376 if (wi::neg_p (shift
))
1379 if (code
== RSHIFT_EXPR
)
1384 if (code
== RSHIFT_EXPR
)
1386 *mask
= wi::rshift (wi::ext (r1mask
, width
, sgn
), shift
, sgn
);
1387 *val
= wi::rshift (wi::ext (r1val
, width
, sgn
), shift
, sgn
);
1391 *mask
= wi::ext (wi::lshift (r1mask
, shift
), width
, sgn
);
1392 *val
= wi::ext (wi::lshift (r1val
, shift
), width
, sgn
);
1399 case POINTER_PLUS_EXPR
:
1401 /* Do the addition with unknown bits set to zero, to give carry-ins of
1402 zero wherever possible. */
1403 widest_int lo
= r1val
.and_not (r1mask
) + r2val
.and_not (r2mask
);
1404 lo
= wi::ext (lo
, width
, sgn
);
1405 /* Do the addition with unknown bits set to one, to give carry-ins of
1406 one wherever possible. */
1407 widest_int hi
= (r1val
| r1mask
) + (r2val
| r2mask
);
1408 hi
= wi::ext (hi
, width
, sgn
);
1409 /* Each bit in the result is known if (a) the corresponding bits in
1410 both inputs are known, and (b) the carry-in to that bit position
1411 is known. We can check condition (b) by seeing if we got the same
1412 result with minimised carries as with maximised carries. */
1413 *mask
= r1mask
| r2mask
| (lo
^ hi
);
1414 *mask
= wi::ext (*mask
, width
, sgn
);
1415 /* It shouldn't matter whether we choose lo or hi here. */
1422 widest_int temv
, temm
;
1423 bit_value_unop_1 (NEGATE_EXPR
, r2type
, &temv
, &temm
,
1424 r2type
, r2val
, r2mask
);
1425 bit_value_binop_1 (PLUS_EXPR
, type
, val
, mask
,
1426 r1type
, r1val
, r1mask
,
1427 r2type
, temv
, temm
);
1433 /* Just track trailing zeros in both operands and transfer
1434 them to the other. */
1435 int r1tz
= wi::ctz (r1val
| r1mask
);
1436 int r2tz
= wi::ctz (r2val
| r2mask
);
1437 if (r1tz
+ r2tz
>= width
)
1442 else if (r1tz
+ r2tz
> 0)
1444 *mask
= wi::ext (wi::mask
<widest_int
> (r1tz
+ r2tz
, true),
1454 widest_int m
= r1mask
| r2mask
;
1455 if (r1val
.and_not (m
) != r2val
.and_not (m
))
1458 *val
= ((code
== EQ_EXPR
) ? 0 : 1);
1462 /* We know the result of a comparison is always one or zero. */
1472 code
= swap_tree_comparison (code
);
1479 const widest_int
&o1val
= swap_p
? r2val
: r1val
;
1480 const widest_int
&o1mask
= swap_p
? r2mask
: r1mask
;
1481 const widest_int
&o2val
= swap_p
? r1val
: r2val
;
1482 const widest_int
&o2mask
= swap_p
? r1mask
: r2mask
;
1484 /* If the most significant bits are not known we know nothing. */
1485 if (wi::neg_p (o1mask
) || wi::neg_p (o2mask
))
1488 /* For comparisons the signedness is in the comparison operands. */
1489 sgn
= TYPE_SIGN (r1type
);
1491 /* If we know the most significant bits we know the values
1492 value ranges by means of treating varying bits as zero
1493 or one. Do a cross comparison of the max/min pairs. */
1494 maxmin
= wi::cmp (o1val
| o1mask
, o2val
.and_not (o2mask
), sgn
);
1495 minmax
= wi::cmp (o1val
.and_not (o1mask
), o2val
| o2mask
, sgn
);
1496 if (maxmin
< 0) /* o1 is less than o2. */
1501 else if (minmax
> 0) /* o1 is not less or equal to o2. */
1506 else if (maxmin
== minmax
) /* o1 and o2 are equal. */
1508 /* This probably should never happen as we'd have
1509 folded the thing during fully constant value folding. */
1511 *val
= (code
== LE_EXPR
? 1 : 0);
1515 /* We know the result of a comparison is always one or zero. */
1526 /* Return the propagation value when applying the operation CODE to
1527 the value RHS yielding type TYPE. */
1529 static ccp_prop_value_t
1530 bit_value_unop (enum tree_code code
, tree type
, tree rhs
)
1532 ccp_prop_value_t rval
= get_value_for_expr (rhs
, true);
1533 widest_int value
, mask
;
1534 ccp_prop_value_t val
;
1536 if (rval
.lattice_val
== UNDEFINED
)
1539 gcc_assert ((rval
.lattice_val
== CONSTANT
1540 && TREE_CODE (rval
.value
) == INTEGER_CST
)
1541 || wi::sext (rval
.mask
, TYPE_PRECISION (TREE_TYPE (rhs
))) == -1);
1542 bit_value_unop_1 (code
, type
, &value
, &mask
,
1543 TREE_TYPE (rhs
), value_to_wide_int (rval
), rval
.mask
);
1544 if (wi::sext (mask
, TYPE_PRECISION (type
)) != -1)
1546 val
.lattice_val
= CONSTANT
;
1548 /* ??? Delay building trees here. */
1549 val
.value
= wide_int_to_tree (type
, value
);
1553 val
.lattice_val
= VARYING
;
1554 val
.value
= NULL_TREE
;
1560 /* Return the propagation value when applying the operation CODE to
1561 the values RHS1 and RHS2 yielding type TYPE. */
1563 static ccp_prop_value_t
1564 bit_value_binop (enum tree_code code
, tree type
, tree rhs1
, tree rhs2
)
1566 ccp_prop_value_t r1val
= get_value_for_expr (rhs1
, true);
1567 ccp_prop_value_t r2val
= get_value_for_expr (rhs2
, true);
1568 widest_int value
, mask
;
1569 ccp_prop_value_t val
;
1571 if (r1val
.lattice_val
== UNDEFINED
1572 || r2val
.lattice_val
== UNDEFINED
)
1574 val
.lattice_val
= VARYING
;
1575 val
.value
= NULL_TREE
;
1580 gcc_assert ((r1val
.lattice_val
== CONSTANT
1581 && TREE_CODE (r1val
.value
) == INTEGER_CST
)
1582 || wi::sext (r1val
.mask
,
1583 TYPE_PRECISION (TREE_TYPE (rhs1
))) == -1);
1584 gcc_assert ((r2val
.lattice_val
== CONSTANT
1585 && TREE_CODE (r2val
.value
) == INTEGER_CST
)
1586 || wi::sext (r2val
.mask
,
1587 TYPE_PRECISION (TREE_TYPE (rhs2
))) == -1);
1588 bit_value_binop_1 (code
, type
, &value
, &mask
,
1589 TREE_TYPE (rhs1
), value_to_wide_int (r1val
), r1val
.mask
,
1590 TREE_TYPE (rhs2
), value_to_wide_int (r2val
), r2val
.mask
);
1591 if (wi::sext (mask
, TYPE_PRECISION (type
)) != -1)
1593 val
.lattice_val
= CONSTANT
;
1595 /* ??? Delay building trees here. */
1596 val
.value
= wide_int_to_tree (type
, value
);
1600 val
.lattice_val
= VARYING
;
1601 val
.value
= NULL_TREE
;
1607 /* Return the propagation value for __builtin_assume_aligned
1608 and functions with assume_aligned or alloc_aligned attribute.
1609 For __builtin_assume_aligned, ATTR is NULL_TREE,
1610 for assume_aligned attribute ATTR is non-NULL and ALLOC_ALIGNED
1611 is false, for alloc_aligned attribute ATTR is non-NULL and
1612 ALLOC_ALIGNED is true. */
1614 static ccp_prop_value_t
1615 bit_value_assume_aligned (gimple stmt
, tree attr
, ccp_prop_value_t ptrval
,
1618 tree align
, misalign
= NULL_TREE
, type
;
1619 unsigned HOST_WIDE_INT aligni
, misaligni
= 0;
1620 ccp_prop_value_t alignval
;
1621 widest_int value
, mask
;
1622 ccp_prop_value_t val
;
1624 if (attr
== NULL_TREE
)
1626 tree ptr
= gimple_call_arg (stmt
, 0);
1627 type
= TREE_TYPE (ptr
);
1628 ptrval
= get_value_for_expr (ptr
, true);
1632 tree lhs
= gimple_call_lhs (stmt
);
1633 type
= TREE_TYPE (lhs
);
1636 if (ptrval
.lattice_val
== UNDEFINED
)
1638 gcc_assert ((ptrval
.lattice_val
== CONSTANT
1639 && TREE_CODE (ptrval
.value
) == INTEGER_CST
)
1640 || wi::sext (ptrval
.mask
, TYPE_PRECISION (type
)) == -1);
1641 if (attr
== NULL_TREE
)
1643 /* Get aligni and misaligni from __builtin_assume_aligned. */
1644 align
= gimple_call_arg (stmt
, 1);
1645 if (!tree_fits_uhwi_p (align
))
1647 aligni
= tree_to_uhwi (align
);
1648 if (gimple_call_num_args (stmt
) > 2)
1650 misalign
= gimple_call_arg (stmt
, 2);
1651 if (!tree_fits_uhwi_p (misalign
))
1653 misaligni
= tree_to_uhwi (misalign
);
1658 /* Get aligni and misaligni from assume_aligned or
1659 alloc_align attributes. */
1660 if (TREE_VALUE (attr
) == NULL_TREE
)
1662 attr
= TREE_VALUE (attr
);
1663 align
= TREE_VALUE (attr
);
1664 if (!tree_fits_uhwi_p (align
))
1666 aligni
= tree_to_uhwi (align
);
1669 if (aligni
== 0 || aligni
> gimple_call_num_args (stmt
))
1671 align
= gimple_call_arg (stmt
, aligni
- 1);
1672 if (!tree_fits_uhwi_p (align
))
1674 aligni
= tree_to_uhwi (align
);
1676 else if (TREE_CHAIN (attr
) && TREE_VALUE (TREE_CHAIN (attr
)))
1678 misalign
= TREE_VALUE (TREE_CHAIN (attr
));
1679 if (!tree_fits_uhwi_p (misalign
))
1681 misaligni
= tree_to_uhwi (misalign
);
1684 if (aligni
<= 1 || (aligni
& (aligni
- 1)) != 0 || misaligni
>= aligni
)
1687 align
= build_int_cst_type (type
, -aligni
);
1688 alignval
= get_value_for_expr (align
, true);
1689 bit_value_binop_1 (BIT_AND_EXPR
, type
, &value
, &mask
,
1690 type
, value_to_wide_int (ptrval
), ptrval
.mask
,
1691 type
, value_to_wide_int (alignval
), alignval
.mask
);
1692 if (wi::sext (mask
, TYPE_PRECISION (type
)) != -1)
1694 val
.lattice_val
= CONSTANT
;
1696 gcc_assert ((mask
.to_uhwi () & (aligni
- 1)) == 0);
1697 gcc_assert ((value
.to_uhwi () & (aligni
- 1)) == 0);
1699 /* ??? Delay building trees here. */
1700 val
.value
= wide_int_to_tree (type
, value
);
1704 val
.lattice_val
= VARYING
;
1705 val
.value
= NULL_TREE
;
1711 /* Evaluate statement STMT.
1712 Valid only for assignments, calls, conditionals, and switches. */
1714 static ccp_prop_value_t
1715 evaluate_stmt (gimple stmt
)
1717 ccp_prop_value_t val
;
1718 tree simplified
= NULL_TREE
;
1719 ccp_lattice_t likelyvalue
= likely_value (stmt
);
1720 bool is_constant
= false;
1723 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1725 fprintf (dump_file
, "which is likely ");
1726 switch (likelyvalue
)
1729 fprintf (dump_file
, "CONSTANT");
1732 fprintf (dump_file
, "UNDEFINED");
1735 fprintf (dump_file
, "VARYING");
1739 fprintf (dump_file
, "\n");
1742 /* If the statement is likely to have a CONSTANT result, then try
1743 to fold the statement to determine the constant value. */
1744 /* FIXME. This is the only place that we call ccp_fold.
1745 Since likely_value never returns CONSTANT for calls, we will
1746 not attempt to fold them, including builtins that may profit. */
1747 if (likelyvalue
== CONSTANT
)
1749 fold_defer_overflow_warnings ();
1750 simplified
= ccp_fold (stmt
);
1751 if (simplified
&& TREE_CODE (simplified
) == SSA_NAME
)
1753 val
= *get_value (simplified
);
1754 if (val
.lattice_val
!= VARYING
)
1756 fold_undefer_overflow_warnings (true, stmt
, 0);
1760 is_constant
= simplified
&& is_gimple_min_invariant (simplified
);
1761 fold_undefer_overflow_warnings (is_constant
, stmt
, 0);
1764 /* The statement produced a constant value. */
1765 val
.lattice_val
= CONSTANT
;
1766 val
.value
= simplified
;
1771 /* If the statement is likely to have a VARYING result, then do not
1772 bother folding the statement. */
1773 else if (likelyvalue
== VARYING
)
1775 enum gimple_code code
= gimple_code (stmt
);
1776 if (code
== GIMPLE_ASSIGN
)
1778 enum tree_code subcode
= gimple_assign_rhs_code (stmt
);
1780 /* Other cases cannot satisfy is_gimple_min_invariant
1782 if (get_gimple_rhs_class (subcode
) == GIMPLE_SINGLE_RHS
)
1783 simplified
= gimple_assign_rhs1 (stmt
);
1785 else if (code
== GIMPLE_SWITCH
)
1786 simplified
= gimple_switch_index (as_a
<gswitch
*> (stmt
));
1788 /* These cannot satisfy is_gimple_min_invariant without folding. */
1789 gcc_assert (code
== GIMPLE_CALL
|| code
== GIMPLE_COND
);
1790 is_constant
= simplified
&& is_gimple_min_invariant (simplified
);
1793 /* The statement produced a constant value. */
1794 val
.lattice_val
= CONSTANT
;
1795 val
.value
= simplified
;
1799 /* If the statement result is likely UNDEFINED, make it so. */
1800 else if (likelyvalue
== UNDEFINED
)
1802 val
.lattice_val
= UNDEFINED
;
1803 val
.value
= NULL_TREE
;
1808 /* Resort to simplification for bitwise tracking. */
1809 if (flag_tree_bit_ccp
1810 && (likelyvalue
== CONSTANT
|| is_gimple_call (stmt
)
1811 || (gimple_assign_single_p (stmt
)
1812 && gimple_assign_rhs_code (stmt
) == ADDR_EXPR
))
1815 enum gimple_code code
= gimple_code (stmt
);
1816 val
.lattice_val
= VARYING
;
1817 val
.value
= NULL_TREE
;
1819 if (code
== GIMPLE_ASSIGN
)
1821 enum tree_code subcode
= gimple_assign_rhs_code (stmt
);
1822 tree rhs1
= gimple_assign_rhs1 (stmt
);
1823 tree lhs
= gimple_assign_lhs (stmt
);
1824 if ((INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
1825 || POINTER_TYPE_P (TREE_TYPE (lhs
)))
1826 && (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1827 || POINTER_TYPE_P (TREE_TYPE (rhs1
))))
1828 switch (get_gimple_rhs_class (subcode
))
1830 case GIMPLE_SINGLE_RHS
:
1831 val
= get_value_for_expr (rhs1
, true);
1834 case GIMPLE_UNARY_RHS
:
1835 val
= bit_value_unop (subcode
, TREE_TYPE (lhs
), rhs1
);
1838 case GIMPLE_BINARY_RHS
:
1839 val
= bit_value_binop (subcode
, TREE_TYPE (lhs
), rhs1
,
1840 gimple_assign_rhs2 (stmt
));
1846 else if (code
== GIMPLE_COND
)
1848 enum tree_code code
= gimple_cond_code (stmt
);
1849 tree rhs1
= gimple_cond_lhs (stmt
);
1850 tree rhs2
= gimple_cond_rhs (stmt
);
1851 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1852 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1853 val
= bit_value_binop (code
, TREE_TYPE (rhs1
), rhs1
, rhs2
);
1855 else if (gimple_call_builtin_p (stmt
, BUILT_IN_NORMAL
))
1857 tree fndecl
= gimple_call_fndecl (stmt
);
1858 switch (DECL_FUNCTION_CODE (fndecl
))
1860 case BUILT_IN_MALLOC
:
1861 case BUILT_IN_REALLOC
:
1862 case BUILT_IN_CALLOC
:
1863 case BUILT_IN_STRDUP
:
1864 case BUILT_IN_STRNDUP
:
1865 val
.lattice_val
= CONSTANT
;
1866 val
.value
= build_int_cst (TREE_TYPE (gimple_get_lhs (stmt
)), 0);
1867 val
.mask
= ~((HOST_WIDE_INT
) MALLOC_ABI_ALIGNMENT
1868 / BITS_PER_UNIT
- 1);
1871 case BUILT_IN_ALLOCA
:
1872 case BUILT_IN_ALLOCA_WITH_ALIGN
:
1873 align
= (DECL_FUNCTION_CODE (fndecl
) == BUILT_IN_ALLOCA_WITH_ALIGN
1874 ? TREE_INT_CST_LOW (gimple_call_arg (stmt
, 1))
1875 : BIGGEST_ALIGNMENT
);
1876 val
.lattice_val
= CONSTANT
;
1877 val
.value
= build_int_cst (TREE_TYPE (gimple_get_lhs (stmt
)), 0);
1878 val
.mask
= ~((HOST_WIDE_INT
) align
/ BITS_PER_UNIT
- 1);
1881 /* These builtins return their first argument, unmodified. */
1882 case BUILT_IN_MEMCPY
:
1883 case BUILT_IN_MEMMOVE
:
1884 case BUILT_IN_MEMSET
:
1885 case BUILT_IN_STRCPY
:
1886 case BUILT_IN_STRNCPY
:
1887 case BUILT_IN_MEMCPY_CHK
:
1888 case BUILT_IN_MEMMOVE_CHK
:
1889 case BUILT_IN_MEMSET_CHK
:
1890 case BUILT_IN_STRCPY_CHK
:
1891 case BUILT_IN_STRNCPY_CHK
:
1892 val
= get_value_for_expr (gimple_call_arg (stmt
, 0), true);
1895 case BUILT_IN_ASSUME_ALIGNED
:
1896 val
= bit_value_assume_aligned (stmt
, NULL_TREE
, val
, false);
1899 case BUILT_IN_ALIGNED_ALLOC
:
1901 tree align
= get_constant_value (gimple_call_arg (stmt
, 0));
1903 && tree_fits_uhwi_p (align
))
1905 unsigned HOST_WIDE_INT aligni
= tree_to_uhwi (align
);
1907 /* align must be power-of-two */
1908 && (aligni
& (aligni
- 1)) == 0)
1910 val
.lattice_val
= CONSTANT
;
1911 val
.value
= build_int_cst (ptr_type_node
, 0);
1921 if (is_gimple_call (stmt
) && gimple_call_lhs (stmt
))
1923 tree fntype
= gimple_call_fntype (stmt
);
1926 tree attrs
= lookup_attribute ("assume_aligned",
1927 TYPE_ATTRIBUTES (fntype
));
1929 val
= bit_value_assume_aligned (stmt
, attrs
, val
, false);
1930 attrs
= lookup_attribute ("alloc_align",
1931 TYPE_ATTRIBUTES (fntype
));
1933 val
= bit_value_assume_aligned (stmt
, attrs
, val
, true);
1936 is_constant
= (val
.lattice_val
== CONSTANT
);
1939 if (flag_tree_bit_ccp
1940 && ((is_constant
&& TREE_CODE (val
.value
) == INTEGER_CST
)
1942 && gimple_get_lhs (stmt
)
1943 && TREE_CODE (gimple_get_lhs (stmt
)) == SSA_NAME
)
1945 tree lhs
= gimple_get_lhs (stmt
);
1946 wide_int nonzero_bits
= get_nonzero_bits (lhs
);
1947 if (nonzero_bits
!= -1)
1951 val
.lattice_val
= CONSTANT
;
1952 val
.value
= build_zero_cst (TREE_TYPE (lhs
));
1953 val
.mask
= extend_mask (nonzero_bits
);
1958 if (wi::bit_and_not (val
.value
, nonzero_bits
) != 0)
1959 val
.value
= wide_int_to_tree (TREE_TYPE (lhs
),
1960 nonzero_bits
& val
.value
);
1961 if (nonzero_bits
== 0)
1964 val
.mask
= val
.mask
& extend_mask (nonzero_bits
);
1969 /* The statement produced a nonconstant value. */
1972 /* The statement produced a copy. */
1973 if (simplified
&& TREE_CODE (simplified
) == SSA_NAME
1974 && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (simplified
))
1976 val
.lattice_val
= CONSTANT
;
1977 val
.value
= simplified
;
1980 /* The statement is VARYING. */
1983 val
.lattice_val
= VARYING
;
1984 val
.value
= NULL_TREE
;
1992 typedef hash_table
<nofree_ptr_hash
<gimple_statement_base
> > gimple_htab
;
1994 /* Given a BUILT_IN_STACK_SAVE value SAVED_VAL, insert a clobber of VAR before
1995 each matching BUILT_IN_STACK_RESTORE. Mark visited phis in VISITED. */
1998 insert_clobber_before_stack_restore (tree saved_val
, tree var
,
1999 gimple_htab
**visited
)
2002 gassign
*clobber_stmt
;
2004 imm_use_iterator iter
;
2005 gimple_stmt_iterator i
;
2008 FOR_EACH_IMM_USE_STMT (stmt
, iter
, saved_val
)
2009 if (gimple_call_builtin_p (stmt
, BUILT_IN_STACK_RESTORE
))
2011 clobber
= build_constructor (TREE_TYPE (var
),
2013 TREE_THIS_VOLATILE (clobber
) = 1;
2014 clobber_stmt
= gimple_build_assign (var
, clobber
);
2016 i
= gsi_for_stmt (stmt
);
2017 gsi_insert_before (&i
, clobber_stmt
, GSI_SAME_STMT
);
2019 else if (gimple_code (stmt
) == GIMPLE_PHI
)
2022 *visited
= new gimple_htab (10);
2024 slot
= (*visited
)->find_slot (stmt
, INSERT
);
2029 insert_clobber_before_stack_restore (gimple_phi_result (stmt
), var
,
2032 else if (gimple_assign_ssa_name_copy_p (stmt
))
2033 insert_clobber_before_stack_restore (gimple_assign_lhs (stmt
), var
,
2035 else if (chkp_gimple_call_builtin_p (stmt
, BUILT_IN_CHKP_BNDRET
))
2038 gcc_assert (is_gimple_debug (stmt
));
2041 /* Advance the iterator to the previous non-debug gimple statement in the same
2042 or dominating basic block. */
2045 gsi_prev_dom_bb_nondebug (gimple_stmt_iterator
*i
)
2049 gsi_prev_nondebug (i
);
2050 while (gsi_end_p (*i
))
2052 dom
= get_immediate_dominator (CDI_DOMINATORS
, i
->bb
);
2053 if (dom
== NULL
|| dom
== ENTRY_BLOCK_PTR_FOR_FN (cfun
))
2056 *i
= gsi_last_bb (dom
);
2060 /* Find a BUILT_IN_STACK_SAVE dominating gsi_stmt (I), and insert
2061 a clobber of VAR before each matching BUILT_IN_STACK_RESTORE.
2063 It is possible that BUILT_IN_STACK_SAVE cannot be find in a dominator when a
2064 previous pass (such as DOM) duplicated it along multiple paths to a BB. In
2065 that case the function gives up without inserting the clobbers. */
2068 insert_clobbers_for_var (gimple_stmt_iterator i
, tree var
)
2072 gimple_htab
*visited
= NULL
;
2074 for (; !gsi_end_p (i
); gsi_prev_dom_bb_nondebug (&i
))
2076 stmt
= gsi_stmt (i
);
2078 if (!gimple_call_builtin_p (stmt
, BUILT_IN_STACK_SAVE
))
2081 saved_val
= gimple_call_lhs (stmt
);
2082 if (saved_val
== NULL_TREE
)
2085 insert_clobber_before_stack_restore (saved_val
, var
, &visited
);
2092 /* Detects a __builtin_alloca_with_align with constant size argument. Declares
2093 fixed-size array and returns the address, if found, otherwise returns
2097 fold_builtin_alloca_with_align (gimple stmt
)
2099 unsigned HOST_WIDE_INT size
, threshold
, n_elem
;
2100 tree lhs
, arg
, block
, var
, elem_type
, array_type
;
2103 lhs
= gimple_call_lhs (stmt
);
2104 if (lhs
== NULL_TREE
)
2107 /* Detect constant argument. */
2108 arg
= get_constant_value (gimple_call_arg (stmt
, 0));
2109 if (arg
== NULL_TREE
2110 || TREE_CODE (arg
) != INTEGER_CST
2111 || !tree_fits_uhwi_p (arg
))
2114 size
= tree_to_uhwi (arg
);
2116 /* Heuristic: don't fold large allocas. */
2117 threshold
= (unsigned HOST_WIDE_INT
)PARAM_VALUE (PARAM_LARGE_STACK_FRAME
);
2118 /* In case the alloca is located at function entry, it has the same lifetime
2119 as a declared array, so we allow a larger size. */
2120 block
= gimple_block (stmt
);
2121 if (!(cfun
->after_inlining
2122 && TREE_CODE (BLOCK_SUPERCONTEXT (block
)) == FUNCTION_DECL
))
2124 if (size
> threshold
)
2127 /* Declare array. */
2128 elem_type
= build_nonstandard_integer_type (BITS_PER_UNIT
, 1);
2129 n_elem
= size
* 8 / BITS_PER_UNIT
;
2130 array_type
= build_array_type_nelts (elem_type
, n_elem
);
2131 var
= create_tmp_var (array_type
);
2132 DECL_ALIGN (var
) = TREE_INT_CST_LOW (gimple_call_arg (stmt
, 1));
2134 struct ptr_info_def
*pi
= SSA_NAME_PTR_INFO (lhs
);
2135 if (pi
!= NULL
&& !pi
->pt
.anything
)
2139 singleton_p
= pt_solution_singleton_p (&pi
->pt
, &uid
);
2140 gcc_assert (singleton_p
);
2141 SET_DECL_PT_UID (var
, uid
);
2145 /* Fold alloca to the address of the array. */
2146 return fold_convert (TREE_TYPE (lhs
), build_fold_addr_expr (var
));
2149 /* Fold the stmt at *GSI with CCP specific information that propagating
2150 and regular folding does not catch. */
2153 ccp_fold_stmt (gimple_stmt_iterator
*gsi
)
2155 gimple stmt
= gsi_stmt (*gsi
);
2157 switch (gimple_code (stmt
))
2161 gcond
*cond_stmt
= as_a
<gcond
*> (stmt
);
2162 ccp_prop_value_t val
;
2163 /* Statement evaluation will handle type mismatches in constants
2164 more gracefully than the final propagation. This allows us to
2165 fold more conditionals here. */
2166 val
= evaluate_stmt (stmt
);
2167 if (val
.lattice_val
!= CONSTANT
2173 fprintf (dump_file
, "Folding predicate ");
2174 print_gimple_expr (dump_file
, stmt
, 0, 0);
2175 fprintf (dump_file
, " to ");
2176 print_generic_expr (dump_file
, val
.value
, 0);
2177 fprintf (dump_file
, "\n");
2180 if (integer_zerop (val
.value
))
2181 gimple_cond_make_false (cond_stmt
);
2183 gimple_cond_make_true (cond_stmt
);
2190 tree lhs
= gimple_call_lhs (stmt
);
2191 int flags
= gimple_call_flags (stmt
);
2194 bool changed
= false;
2197 /* If the call was folded into a constant make sure it goes
2198 away even if we cannot propagate into all uses because of
2201 && TREE_CODE (lhs
) == SSA_NAME
2202 && (val
= get_constant_value (lhs
))
2203 /* Don't optimize away calls that have side-effects. */
2204 && (flags
& (ECF_CONST
|ECF_PURE
)) != 0
2205 && (flags
& ECF_LOOPING_CONST_OR_PURE
) == 0)
2207 tree new_rhs
= unshare_expr (val
);
2209 if (!useless_type_conversion_p (TREE_TYPE (lhs
),
2210 TREE_TYPE (new_rhs
)))
2211 new_rhs
= fold_convert (TREE_TYPE (lhs
), new_rhs
);
2212 res
= update_call_from_tree (gsi
, new_rhs
);
2217 /* Internal calls provide no argument types, so the extra laxity
2218 for normal calls does not apply. */
2219 if (gimple_call_internal_p (stmt
))
2222 /* The heuristic of fold_builtin_alloca_with_align differs before and
2223 after inlining, so we don't require the arg to be changed into a
2224 constant for folding, but just to be constant. */
2225 if (gimple_call_builtin_p (stmt
, BUILT_IN_ALLOCA_WITH_ALIGN
))
2227 tree new_rhs
= fold_builtin_alloca_with_align (stmt
);
2230 bool res
= update_call_from_tree (gsi
, new_rhs
);
2231 tree var
= TREE_OPERAND (TREE_OPERAND (new_rhs
, 0),0);
2233 insert_clobbers_for_var (*gsi
, var
);
2238 /* Propagate into the call arguments. Compared to replace_uses_in
2239 this can use the argument slot types for type verification
2240 instead of the current argument type. We also can safely
2241 drop qualifiers here as we are dealing with constants anyway. */
2242 argt
= TYPE_ARG_TYPES (gimple_call_fntype (stmt
));
2243 for (i
= 0; i
< gimple_call_num_args (stmt
) && argt
;
2244 ++i
, argt
= TREE_CHAIN (argt
))
2246 tree arg
= gimple_call_arg (stmt
, i
);
2247 if (TREE_CODE (arg
) == SSA_NAME
2248 && (val
= get_constant_value (arg
))
2249 && useless_type_conversion_p
2250 (TYPE_MAIN_VARIANT (TREE_VALUE (argt
)),
2251 TYPE_MAIN_VARIANT (TREE_TYPE (val
))))
2253 gimple_call_set_arg (stmt
, i
, unshare_expr (val
));
2263 tree lhs
= gimple_assign_lhs (stmt
);
2266 /* If we have a load that turned out to be constant replace it
2267 as we cannot propagate into all uses in all cases. */
2268 if (gimple_assign_single_p (stmt
)
2269 && TREE_CODE (lhs
) == SSA_NAME
2270 && (val
= get_constant_value (lhs
)))
2272 tree rhs
= unshare_expr (val
);
2273 if (!useless_type_conversion_p (TREE_TYPE (lhs
), TREE_TYPE (rhs
)))
2274 rhs
= fold_build1 (VIEW_CONVERT_EXPR
, TREE_TYPE (lhs
), rhs
);
2275 gimple_assign_set_rhs_from_tree (gsi
, rhs
);
2287 /* Visit the assignment statement STMT. Set the value of its LHS to the
2288 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
2289 creates virtual definitions, set the value of each new name to that
2290 of the RHS (if we can derive a constant out of the RHS).
2291 Value-returning call statements also perform an assignment, and
2292 are handled here. */
2294 static enum ssa_prop_result
2295 visit_assignment (gimple stmt
, tree
*output_p
)
2297 ccp_prop_value_t val
;
2298 enum ssa_prop_result retval
= SSA_PROP_NOT_INTERESTING
;
2300 tree lhs
= gimple_get_lhs (stmt
);
2301 if (TREE_CODE (lhs
) == SSA_NAME
)
2303 /* Evaluate the statement, which could be
2304 either a GIMPLE_ASSIGN or a GIMPLE_CALL. */
2305 val
= evaluate_stmt (stmt
);
2307 /* If STMT is an assignment to an SSA_NAME, we only have one
2309 if (set_lattice_value (lhs
, &val
))
2312 if (val
.lattice_val
== VARYING
)
2313 retval
= SSA_PROP_VARYING
;
2315 retval
= SSA_PROP_INTERESTING
;
2323 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
2324 if it can determine which edge will be taken. Otherwise, return
2325 SSA_PROP_VARYING. */
2327 static enum ssa_prop_result
2328 visit_cond_stmt (gimple stmt
, edge
*taken_edge_p
)
2330 ccp_prop_value_t val
;
2333 block
= gimple_bb (stmt
);
2334 val
= evaluate_stmt (stmt
);
2335 if (val
.lattice_val
!= CONSTANT
2337 return SSA_PROP_VARYING
;
2339 /* Find which edge out of the conditional block will be taken and add it
2340 to the worklist. If no single edge can be determined statically,
2341 return SSA_PROP_VARYING to feed all the outgoing edges to the
2342 propagation engine. */
2343 *taken_edge_p
= find_taken_edge (block
, val
.value
);
2345 return SSA_PROP_INTERESTING
;
2347 return SSA_PROP_VARYING
;
2351 /* Evaluate statement STMT. If the statement produces an output value and
2352 its evaluation changes the lattice value of its output, return
2353 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
2356 If STMT is a conditional branch and we can determine its truth
2357 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
2358 value, return SSA_PROP_VARYING. */
2360 static enum ssa_prop_result
2361 ccp_visit_stmt (gimple stmt
, edge
*taken_edge_p
, tree
*output_p
)
2366 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2368 fprintf (dump_file
, "\nVisiting statement:\n");
2369 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2372 switch (gimple_code (stmt
))
2375 /* If the statement is an assignment that produces a single
2376 output value, evaluate its RHS to see if the lattice value of
2377 its output has changed. */
2378 return visit_assignment (stmt
, output_p
);
2381 /* A value-returning call also performs an assignment. */
2382 if (gimple_call_lhs (stmt
) != NULL_TREE
)
2383 return visit_assignment (stmt
, output_p
);
2388 /* If STMT is a conditional branch, see if we can determine
2389 which branch will be taken. */
2390 /* FIXME. It appears that we should be able to optimize
2391 computed GOTOs here as well. */
2392 return visit_cond_stmt (stmt
, taken_edge_p
);
2398 /* Any other kind of statement is not interesting for constant
2399 propagation and, therefore, not worth simulating. */
2400 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2401 fprintf (dump_file
, "No interesting values produced. Marked VARYING.\n");
2403 /* Definitions made by statements other than assignments to
2404 SSA_NAMEs represent unknown modifications to their outputs.
2405 Mark them VARYING. */
2406 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
2407 set_value_varying (def
);
2409 return SSA_PROP_VARYING
;
2413 /* Main entry point for SSA Conditional Constant Propagation. */
2418 unsigned int todo
= 0;
2419 calculate_dominance_info (CDI_DOMINATORS
);
2421 ssa_propagate (ccp_visit_stmt
, ccp_visit_phi_node
);
2422 if (ccp_finalize ())
2423 todo
= (TODO_cleanup_cfg
| TODO_update_ssa
);
2424 free_dominance_info (CDI_DOMINATORS
);
2431 const pass_data pass_data_ccp
=
2433 GIMPLE_PASS
, /* type */
2435 OPTGROUP_NONE
, /* optinfo_flags */
2436 TV_TREE_CCP
, /* tv_id */
2437 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2438 0, /* properties_provided */
2439 0, /* properties_destroyed */
2440 0, /* todo_flags_start */
2441 TODO_update_address_taken
, /* todo_flags_finish */
2444 class pass_ccp
: public gimple_opt_pass
2447 pass_ccp (gcc::context
*ctxt
)
2448 : gimple_opt_pass (pass_data_ccp
, ctxt
)
2451 /* opt_pass methods: */
2452 opt_pass
* clone () { return new pass_ccp (m_ctxt
); }
2453 virtual bool gate (function
*) { return flag_tree_ccp
!= 0; }
2454 virtual unsigned int execute (function
*) { return do_ssa_ccp (); }
2456 }; // class pass_ccp
2461 make_pass_ccp (gcc::context
*ctxt
)
2463 return new pass_ccp (ctxt
);
2468 /* Try to optimize out __builtin_stack_restore. Optimize it out
2469 if there is another __builtin_stack_restore in the same basic
2470 block and no calls or ASM_EXPRs are in between, or if this block's
2471 only outgoing edge is to EXIT_BLOCK and there are no calls or
2472 ASM_EXPRs after this __builtin_stack_restore. */
2475 optimize_stack_restore (gimple_stmt_iterator i
)
2480 basic_block bb
= gsi_bb (i
);
2481 gimple call
= gsi_stmt (i
);
2483 if (gimple_code (call
) != GIMPLE_CALL
2484 || gimple_call_num_args (call
) != 1
2485 || TREE_CODE (gimple_call_arg (call
, 0)) != SSA_NAME
2486 || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call
, 0))))
2489 for (gsi_next (&i
); !gsi_end_p (i
); gsi_next (&i
))
2491 stmt
= gsi_stmt (i
);
2492 if (gimple_code (stmt
) == GIMPLE_ASM
)
2494 if (gimple_code (stmt
) != GIMPLE_CALL
)
2497 callee
= gimple_call_fndecl (stmt
);
2499 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2500 /* All regular builtins are ok, just obviously not alloca. */
2501 || DECL_FUNCTION_CODE (callee
) == BUILT_IN_ALLOCA
2502 || DECL_FUNCTION_CODE (callee
) == BUILT_IN_ALLOCA_WITH_ALIGN
)
2505 if (DECL_FUNCTION_CODE (callee
) == BUILT_IN_STACK_RESTORE
)
2506 goto second_stack_restore
;
2512 /* Allow one successor of the exit block, or zero successors. */
2513 switch (EDGE_COUNT (bb
->succs
))
2518 if (single_succ_edge (bb
)->dest
!= EXIT_BLOCK_PTR_FOR_FN (cfun
))
2524 second_stack_restore
:
2526 /* If there's exactly one use, then zap the call to __builtin_stack_save.
2527 If there are multiple uses, then the last one should remove the call.
2528 In any case, whether the call to __builtin_stack_save can be removed
2529 or not is irrelevant to removing the call to __builtin_stack_restore. */
2530 if (has_single_use (gimple_call_arg (call
, 0)))
2532 gimple stack_save
= SSA_NAME_DEF_STMT (gimple_call_arg (call
, 0));
2533 if (is_gimple_call (stack_save
))
2535 callee
= gimple_call_fndecl (stack_save
);
2537 && DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
2538 && DECL_FUNCTION_CODE (callee
) == BUILT_IN_STACK_SAVE
)
2540 gimple_stmt_iterator stack_save_gsi
;
2543 stack_save_gsi
= gsi_for_stmt (stack_save
);
2544 rhs
= build_int_cst (TREE_TYPE (gimple_call_arg (call
, 0)), 0);
2545 update_call_from_tree (&stack_save_gsi
, rhs
);
2550 /* No effect, so the statement will be deleted. */
2551 return integer_zero_node
;
2554 /* If va_list type is a simple pointer and nothing special is needed,
2555 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
2556 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
2557 pointer assignment. */
2560 optimize_stdarg_builtin (gimple call
)
2562 tree callee
, lhs
, rhs
, cfun_va_list
;
2563 bool va_list_simple_ptr
;
2564 location_t loc
= gimple_location (call
);
2566 if (gimple_code (call
) != GIMPLE_CALL
)
2569 callee
= gimple_call_fndecl (call
);
2571 cfun_va_list
= targetm
.fn_abi_va_list (callee
);
2572 va_list_simple_ptr
= POINTER_TYPE_P (cfun_va_list
)
2573 && (TREE_TYPE (cfun_va_list
) == void_type_node
2574 || TREE_TYPE (cfun_va_list
) == char_type_node
);
2576 switch (DECL_FUNCTION_CODE (callee
))
2578 case BUILT_IN_VA_START
:
2579 if (!va_list_simple_ptr
2580 || targetm
.expand_builtin_va_start
!= NULL
2581 || !builtin_decl_explicit_p (BUILT_IN_NEXT_ARG
))
2584 if (gimple_call_num_args (call
) != 2)
2587 lhs
= gimple_call_arg (call
, 0);
2588 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2589 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2590 != TYPE_MAIN_VARIANT (cfun_va_list
))
2593 lhs
= build_fold_indirect_ref_loc (loc
, lhs
);
2594 rhs
= build_call_expr_loc (loc
, builtin_decl_explicit (BUILT_IN_NEXT_ARG
),
2595 1, integer_zero_node
);
2596 rhs
= fold_convert_loc (loc
, TREE_TYPE (lhs
), rhs
);
2597 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2599 case BUILT_IN_VA_COPY
:
2600 if (!va_list_simple_ptr
)
2603 if (gimple_call_num_args (call
) != 2)
2606 lhs
= gimple_call_arg (call
, 0);
2607 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2608 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2609 != TYPE_MAIN_VARIANT (cfun_va_list
))
2612 lhs
= build_fold_indirect_ref_loc (loc
, lhs
);
2613 rhs
= gimple_call_arg (call
, 1);
2614 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs
))
2615 != TYPE_MAIN_VARIANT (cfun_va_list
))
2618 rhs
= fold_convert_loc (loc
, TREE_TYPE (lhs
), rhs
);
2619 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2621 case BUILT_IN_VA_END
:
2622 /* No effect, so the statement will be deleted. */
2623 return integer_zero_node
;
2630 /* Attemp to make the block of __builtin_unreachable I unreachable by changing
2631 the incoming jumps. Return true if at least one jump was changed. */
2634 optimize_unreachable (gimple_stmt_iterator i
)
2636 basic_block bb
= gsi_bb (i
);
2637 gimple_stmt_iterator gsi
;
2643 if (flag_sanitize
& SANITIZE_UNREACHABLE
)
2646 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
2648 stmt
= gsi_stmt (gsi
);
2650 if (is_gimple_debug (stmt
))
2653 if (glabel
*label_stmt
= dyn_cast
<glabel
*> (stmt
))
2655 /* Verify we do not need to preserve the label. */
2656 if (FORCED_LABEL (gimple_label_label (label_stmt
)))
2662 /* Only handle the case that __builtin_unreachable is the first statement
2663 in the block. We rely on DCE to remove stmts without side-effects
2664 before __builtin_unreachable. */
2665 if (gsi_stmt (gsi
) != gsi_stmt (i
))
2670 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
2672 gsi
= gsi_last_bb (e
->src
);
2673 if (gsi_end_p (gsi
))
2676 stmt
= gsi_stmt (gsi
);
2677 if (gcond
*cond_stmt
= dyn_cast
<gcond
*> (stmt
))
2679 if (e
->flags
& EDGE_TRUE_VALUE
)
2680 gimple_cond_make_false (cond_stmt
);
2681 else if (e
->flags
& EDGE_FALSE_VALUE
)
2682 gimple_cond_make_true (cond_stmt
);
2685 update_stmt (cond_stmt
);
2689 /* Todo: handle other cases, f.i. switch statement. */
2699 /* A simple pass that attempts to fold all builtin functions. This pass
2700 is run after we've propagated as many constants as we can. */
2704 const pass_data pass_data_fold_builtins
=
2706 GIMPLE_PASS
, /* type */
2708 OPTGROUP_NONE
, /* optinfo_flags */
2709 TV_NONE
, /* tv_id */
2710 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2711 0, /* properties_provided */
2712 0, /* properties_destroyed */
2713 0, /* todo_flags_start */
2714 TODO_update_ssa
, /* todo_flags_finish */
2717 class pass_fold_builtins
: public gimple_opt_pass
2720 pass_fold_builtins (gcc::context
*ctxt
)
2721 : gimple_opt_pass (pass_data_fold_builtins
, ctxt
)
2724 /* opt_pass methods: */
2725 opt_pass
* clone () { return new pass_fold_builtins (m_ctxt
); }
2726 virtual unsigned int execute (function
*);
2728 }; // class pass_fold_builtins
2731 pass_fold_builtins::execute (function
*fun
)
2733 bool cfg_changed
= false;
2735 unsigned int todoflags
= 0;
2737 FOR_EACH_BB_FN (bb
, fun
)
2739 gimple_stmt_iterator i
;
2740 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); )
2742 gimple stmt
, old_stmt
;
2744 enum built_in_function fcode
;
2746 stmt
= gsi_stmt (i
);
2748 if (gimple_code (stmt
) != GIMPLE_CALL
)
2750 /* Remove all *ssaname_N ={v} {CLOBBER}; stmts,
2751 after the last GIMPLE DSE they aren't needed and might
2752 unnecessarily keep the SSA_NAMEs live. */
2753 if (gimple_clobber_p (stmt
))
2755 tree lhs
= gimple_assign_lhs (stmt
);
2756 if (TREE_CODE (lhs
) == MEM_REF
2757 && TREE_CODE (TREE_OPERAND (lhs
, 0)) == SSA_NAME
)
2759 unlink_stmt_vdef (stmt
);
2760 gsi_remove (&i
, true);
2761 release_defs (stmt
);
2769 callee
= gimple_call_fndecl (stmt
);
2770 if (!callee
|| DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
)
2776 fcode
= DECL_FUNCTION_CODE (callee
);
2781 tree result
= NULL_TREE
;
2782 switch (DECL_FUNCTION_CODE (callee
))
2784 case BUILT_IN_CONSTANT_P
:
2785 /* Resolve __builtin_constant_p. If it hasn't been
2786 folded to integer_one_node by now, it's fairly
2787 certain that the value simply isn't constant. */
2788 result
= integer_zero_node
;
2791 case BUILT_IN_ASSUME_ALIGNED
:
2792 /* Remove __builtin_assume_aligned. */
2793 result
= gimple_call_arg (stmt
, 0);
2796 case BUILT_IN_STACK_RESTORE
:
2797 result
= optimize_stack_restore (i
);
2803 case BUILT_IN_UNREACHABLE
:
2804 if (optimize_unreachable (i
))
2808 case BUILT_IN_VA_START
:
2809 case BUILT_IN_VA_END
:
2810 case BUILT_IN_VA_COPY
:
2811 /* These shouldn't be folded before pass_stdarg. */
2812 result
= optimize_stdarg_builtin (stmt
);
2826 if (!update_call_from_tree (&i
, result
))
2827 gimplify_and_update_call_from_tree (&i
, result
);
2830 todoflags
|= TODO_update_address_taken
;
2832 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2834 fprintf (dump_file
, "Simplified\n ");
2835 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2839 stmt
= gsi_stmt (i
);
2842 if (maybe_clean_or_replace_eh_stmt (old_stmt
, stmt
)
2843 && gimple_purge_dead_eh_edges (bb
))
2846 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2848 fprintf (dump_file
, "to\n ");
2849 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2850 fprintf (dump_file
, "\n");
2853 /* Retry the same statement if it changed into another
2854 builtin, there might be new opportunities now. */
2855 if (gimple_code (stmt
) != GIMPLE_CALL
)
2860 callee
= gimple_call_fndecl (stmt
);
2862 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2863 || DECL_FUNCTION_CODE (callee
) == fcode
)
2868 /* Delete unreachable blocks. */
2870 todoflags
|= TODO_cleanup_cfg
;
2878 make_pass_fold_builtins (gcc::context
*ctxt
)
2880 return new pass_fold_builtins (ctxt
);