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"
127 #include "hard-reg-set.h"
130 #include "fold-const.h"
131 #include "stor-layout.h"
134 #include "gimple-pretty-print.h"
135 #include "internal-fn.h"
136 #include "gimple-fold.h"
138 #include "gimplify.h"
139 #include "gimple-iterator.h"
140 #include "tree-cfg.h"
141 #include "tree-pass.h"
142 #include "tree-ssa-propagate.h"
143 #include "value-prof.h"
144 #include "langhooks.h"
146 #include "diagnostic-core.h"
149 #include "wide-int-print.h"
150 #include "builtins.h"
151 #include "tree-chkp.h"
154 /* Possible lattice values. */
163 struct ccp_prop_value_t
{
165 ccp_lattice_t lattice_val
;
167 /* Propagated value. */
170 /* Mask that applies to the propagated value during CCP. For X
171 with a CONSTANT lattice value X & ~mask == value & ~mask. The
172 zero bits in the mask cover constant values. The ones mean no
177 /* Array of propagated constant values. After propagation,
178 CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If
179 the constant is held in an SSA name representing a memory store
180 (i.e., a VDEF), CONST_VAL[I].MEM_REF will contain the actual
181 memory reference used to store (i.e., the LHS of the assignment
183 static ccp_prop_value_t
*const_val
;
184 static unsigned n_const_val
;
186 static void canonicalize_value (ccp_prop_value_t
*);
187 static bool ccp_fold_stmt (gimple_stmt_iterator
*);
188 static void ccp_lattice_meet (ccp_prop_value_t
*, ccp_prop_value_t
*);
190 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */
193 dump_lattice_value (FILE *outf
, const char *prefix
, ccp_prop_value_t val
)
195 switch (val
.lattice_val
)
198 fprintf (outf
, "%sUNINITIALIZED", prefix
);
201 fprintf (outf
, "%sUNDEFINED", prefix
);
204 fprintf (outf
, "%sVARYING", prefix
);
207 if (TREE_CODE (val
.value
) != INTEGER_CST
210 fprintf (outf
, "%sCONSTANT ", prefix
);
211 print_generic_expr (outf
, val
.value
, dump_flags
);
215 widest_int cval
= wi::bit_and_not (wi::to_widest (val
.value
),
217 fprintf (outf
, "%sCONSTANT ", prefix
);
218 print_hex (cval
, outf
);
219 fprintf (outf
, " (");
220 print_hex (val
.mask
, outf
);
230 /* Print lattice value VAL to stderr. */
232 void debug_lattice_value (ccp_prop_value_t val
);
235 debug_lattice_value (ccp_prop_value_t val
)
237 dump_lattice_value (stderr
, "", val
);
238 fprintf (stderr
, "\n");
241 /* Extend NONZERO_BITS to a full mask, with the upper bits being set. */
244 extend_mask (const wide_int
&nonzero_bits
)
246 return (wi::mask
<widest_int
> (wi::get_precision (nonzero_bits
), true)
247 | widest_int::from (nonzero_bits
, UNSIGNED
));
250 /* Compute a default value for variable VAR and store it in the
251 CONST_VAL array. The following rules are used to get default
254 1- Global and static variables that are declared constant are
257 2- Any other value is considered UNDEFINED. This is useful when
258 considering PHI nodes. PHI arguments that are undefined do not
259 change the constant value of the PHI node, which allows for more
260 constants to be propagated.
262 3- Variables defined by statements other than assignments and PHI
263 nodes are considered VARYING.
265 4- Initial values of variables that are not GIMPLE registers are
266 considered VARYING. */
268 static ccp_prop_value_t
269 get_default_value (tree var
)
271 ccp_prop_value_t val
= { UNINITIALIZED
, NULL_TREE
, 0 };
274 stmt
= SSA_NAME_DEF_STMT (var
);
276 if (gimple_nop_p (stmt
))
278 /* Variables defined by an empty statement are those used
279 before being initialized. If VAR is a local variable, we
280 can assume initially that it is UNDEFINED, otherwise we must
281 consider it VARYING. */
282 if (!virtual_operand_p (var
)
283 && TREE_CODE (SSA_NAME_VAR (var
)) == VAR_DECL
)
284 val
.lattice_val
= UNDEFINED
;
287 val
.lattice_val
= VARYING
;
289 if (flag_tree_bit_ccp
)
291 wide_int nonzero_bits
= get_nonzero_bits (var
);
292 if (nonzero_bits
!= -1)
294 val
.lattice_val
= CONSTANT
;
295 val
.value
= build_zero_cst (TREE_TYPE (var
));
296 val
.mask
= extend_mask (nonzero_bits
);
301 else if (is_gimple_assign (stmt
))
304 if (gimple_assign_single_p (stmt
)
305 && DECL_P (gimple_assign_rhs1 (stmt
))
306 && (cst
= get_symbol_constant_value (gimple_assign_rhs1 (stmt
))))
308 val
.lattice_val
= CONSTANT
;
313 /* Any other variable defined by an assignment is considered
315 val
.lattice_val
= UNDEFINED
;
318 else if ((is_gimple_call (stmt
)
319 && gimple_call_lhs (stmt
) != NULL_TREE
)
320 || gimple_code (stmt
) == GIMPLE_PHI
)
322 /* A variable defined by a call or a PHI node is considered
324 val
.lattice_val
= UNDEFINED
;
328 /* Otherwise, VAR will never take on a constant value. */
329 val
.lattice_val
= VARYING
;
337 /* Get the constant value associated with variable VAR. */
339 static inline ccp_prop_value_t
*
342 ccp_prop_value_t
*val
;
344 if (const_val
== NULL
345 || SSA_NAME_VERSION (var
) >= n_const_val
)
348 val
= &const_val
[SSA_NAME_VERSION (var
)];
349 if (val
->lattice_val
== UNINITIALIZED
)
350 *val
= get_default_value (var
);
352 canonicalize_value (val
);
357 /* Return the constant tree value associated with VAR. */
360 get_constant_value (tree var
)
362 ccp_prop_value_t
*val
;
363 if (TREE_CODE (var
) != SSA_NAME
)
365 if (is_gimple_min_invariant (var
))
369 val
= get_value (var
);
371 && val
->lattice_val
== CONSTANT
372 && (TREE_CODE (val
->value
) != INTEGER_CST
378 /* Sets the value associated with VAR to VARYING. */
381 set_value_varying (tree var
)
383 ccp_prop_value_t
*val
= &const_val
[SSA_NAME_VERSION (var
)];
385 val
->lattice_val
= VARYING
;
386 val
->value
= NULL_TREE
;
390 /* For integer constants, make sure to drop TREE_OVERFLOW. */
393 canonicalize_value (ccp_prop_value_t
*val
)
395 if (val
->lattice_val
!= CONSTANT
)
398 if (TREE_OVERFLOW_P (val
->value
))
399 val
->value
= drop_tree_overflow (val
->value
);
402 /* Return whether the lattice transition is valid. */
405 valid_lattice_transition (ccp_prop_value_t old_val
, ccp_prop_value_t new_val
)
407 /* Lattice transitions must always be monotonically increasing in
409 if (old_val
.lattice_val
< new_val
.lattice_val
)
412 if (old_val
.lattice_val
!= new_val
.lattice_val
)
415 if (!old_val
.value
&& !new_val
.value
)
418 /* Now both lattice values are CONSTANT. */
420 /* Allow arbitrary copy changes as we might look through PHI <a_1, ...>
421 when only a single copy edge is executable. */
422 if (TREE_CODE (old_val
.value
) == SSA_NAME
423 && TREE_CODE (new_val
.value
) == SSA_NAME
)
426 /* Allow transitioning from a constant to a copy. */
427 if (is_gimple_min_invariant (old_val
.value
)
428 && TREE_CODE (new_val
.value
) == SSA_NAME
)
431 /* Allow transitioning from PHI <&x, not executable> == &x
432 to PHI <&x, &y> == common alignment. */
433 if (TREE_CODE (old_val
.value
) != INTEGER_CST
434 && TREE_CODE (new_val
.value
) == INTEGER_CST
)
437 /* Bit-lattices have to agree in the still valid bits. */
438 if (TREE_CODE (old_val
.value
) == INTEGER_CST
439 && TREE_CODE (new_val
.value
) == INTEGER_CST
)
440 return (wi::bit_and_not (wi::to_widest (old_val
.value
), new_val
.mask
)
441 == wi::bit_and_not (wi::to_widest (new_val
.value
), new_val
.mask
));
443 /* Otherwise constant values have to agree. */
444 if (operand_equal_p (old_val
.value
, new_val
.value
, 0))
447 /* At least the kinds and types should agree now. */
448 if (TREE_CODE (old_val
.value
) != TREE_CODE (new_val
.value
)
449 || !types_compatible_p (TREE_TYPE (old_val
.value
),
450 TREE_TYPE (new_val
.value
)))
453 /* For floats and !HONOR_NANS allow transitions from (partial) NaN
455 tree type
= TREE_TYPE (new_val
.value
);
456 if (SCALAR_FLOAT_TYPE_P (type
)
457 && !HONOR_NANS (type
))
459 if (REAL_VALUE_ISNAN (TREE_REAL_CST (old_val
.value
)))
462 else if (VECTOR_FLOAT_TYPE_P (type
)
463 && !HONOR_NANS (type
))
465 for (unsigned i
= 0; i
< VECTOR_CST_NELTS (old_val
.value
); ++i
)
466 if (!REAL_VALUE_ISNAN
467 (TREE_REAL_CST (VECTOR_CST_ELT (old_val
.value
, i
)))
468 && !operand_equal_p (VECTOR_CST_ELT (old_val
.value
, i
),
469 VECTOR_CST_ELT (new_val
.value
, i
), 0))
473 else if (COMPLEX_FLOAT_TYPE_P (type
)
474 && !HONOR_NANS (type
))
476 if (!REAL_VALUE_ISNAN (TREE_REAL_CST (TREE_REALPART (old_val
.value
)))
477 && !operand_equal_p (TREE_REALPART (old_val
.value
),
478 TREE_REALPART (new_val
.value
), 0))
480 if (!REAL_VALUE_ISNAN (TREE_REAL_CST (TREE_IMAGPART (old_val
.value
)))
481 && !operand_equal_p (TREE_IMAGPART (old_val
.value
),
482 TREE_IMAGPART (new_val
.value
), 0))
489 /* Set the value for variable VAR to NEW_VAL. Return true if the new
490 value is different from VAR's previous value. */
493 set_lattice_value (tree var
, ccp_prop_value_t
*new_val
)
495 /* We can deal with old UNINITIALIZED values just fine here. */
496 ccp_prop_value_t
*old_val
= &const_val
[SSA_NAME_VERSION (var
)];
498 canonicalize_value (new_val
);
500 /* We have to be careful to not go up the bitwise lattice
501 represented by the mask. Instead of dropping to VARYING
502 use the meet operator to retain a conservative value.
503 Missed optimizations like PR65851 makes this necessary.
504 It also ensures we converge to a stable lattice solution. */
505 if (new_val
->lattice_val
== CONSTANT
506 && old_val
->lattice_val
== CONSTANT
507 && TREE_CODE (new_val
->value
) != SSA_NAME
)
508 ccp_lattice_meet (new_val
, old_val
);
510 gcc_checking_assert (valid_lattice_transition (*old_val
, *new_val
));
512 /* If *OLD_VAL and NEW_VAL are the same, return false to inform the
513 caller that this was a non-transition. */
514 if (old_val
->lattice_val
!= new_val
->lattice_val
515 || (new_val
->lattice_val
== CONSTANT
516 && (TREE_CODE (new_val
->value
) != TREE_CODE (old_val
->value
)
517 || (TREE_CODE (new_val
->value
) == INTEGER_CST
518 && (new_val
->mask
!= old_val
->mask
519 || (wi::bit_and_not (wi::to_widest (old_val
->value
),
521 != wi::bit_and_not (wi::to_widest (new_val
->value
),
523 || (TREE_CODE (new_val
->value
) != INTEGER_CST
524 && !operand_equal_p (new_val
->value
, old_val
->value
, 0)))))
526 /* ??? We would like to delay creation of INTEGER_CSTs from
527 partially constants here. */
529 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
531 dump_lattice_value (dump_file
, "Lattice value changed to ", *new_val
);
532 fprintf (dump_file
, ". Adding SSA edges to worklist.\n");
537 gcc_assert (new_val
->lattice_val
!= UNINITIALIZED
);
544 static ccp_prop_value_t
get_value_for_expr (tree
, bool);
545 static ccp_prop_value_t
bit_value_binop (enum tree_code
, tree
, tree
, tree
);
546 static void bit_value_binop_1 (enum tree_code
, tree
, widest_int
*, widest_int
*,
547 tree
, const widest_int
&, const widest_int
&,
548 tree
, const widest_int
&, const widest_int
&);
550 /* Return a widest_int that can be used for bitwise simplifications
554 value_to_wide_int (ccp_prop_value_t val
)
557 && TREE_CODE (val
.value
) == INTEGER_CST
)
558 return wi::to_widest (val
.value
);
563 /* Return the value for the address expression EXPR based on alignment
566 static ccp_prop_value_t
567 get_value_from_alignment (tree expr
)
569 tree type
= TREE_TYPE (expr
);
570 ccp_prop_value_t val
;
571 unsigned HOST_WIDE_INT bitpos
;
574 gcc_assert (TREE_CODE (expr
) == ADDR_EXPR
);
576 get_pointer_alignment_1 (expr
, &align
, &bitpos
);
577 val
.mask
= (POINTER_TYPE_P (type
) || TYPE_UNSIGNED (type
)
578 ? wi::mask
<widest_int
> (TYPE_PRECISION (type
), false)
579 : -1).and_not (align
/ BITS_PER_UNIT
- 1);
581 = wi::sext (val
.mask
, TYPE_PRECISION (type
)) == -1 ? VARYING
: CONSTANT
;
582 if (val
.lattice_val
== CONSTANT
)
583 val
.value
= build_int_cstu (type
, bitpos
/ BITS_PER_UNIT
);
585 val
.value
= NULL_TREE
;
590 /* Return the value for the tree operand EXPR. If FOR_BITS_P is true
591 return constant bits extracted from alignment information for
592 invariant addresses. */
594 static ccp_prop_value_t
595 get_value_for_expr (tree expr
, bool for_bits_p
)
597 ccp_prop_value_t val
;
599 if (TREE_CODE (expr
) == SSA_NAME
)
601 val
= *get_value (expr
);
603 && val
.lattice_val
== CONSTANT
604 && TREE_CODE (val
.value
) == ADDR_EXPR
)
605 val
= get_value_from_alignment (val
.value
);
606 /* Fall back to a copy value. */
608 && val
.lattice_val
== VARYING
609 && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (expr
))
611 val
.lattice_val
= CONSTANT
;
616 else if (is_gimple_min_invariant (expr
)
617 && (!for_bits_p
|| TREE_CODE (expr
) != ADDR_EXPR
))
619 val
.lattice_val
= CONSTANT
;
622 canonicalize_value (&val
);
624 else if (TREE_CODE (expr
) == ADDR_EXPR
)
625 val
= get_value_from_alignment (expr
);
628 val
.lattice_val
= VARYING
;
630 val
.value
= NULL_TREE
;
633 if (val
.lattice_val
== VARYING
634 && TYPE_UNSIGNED (TREE_TYPE (expr
)))
635 val
.mask
= wi::zext (val
.mask
, TYPE_PRECISION (TREE_TYPE (expr
)));
640 /* Return the likely CCP lattice value for STMT.
642 If STMT has no operands, then return CONSTANT.
644 Else if undefinedness of operands of STMT cause its value to be
645 undefined, then return UNDEFINED.
647 Else if any operands of STMT are constants, then return CONSTANT.
649 Else return VARYING. */
652 likely_value (gimple
*stmt
)
654 bool has_constant_operand
, has_undefined_operand
, all_undefined_operands
;
655 bool has_nsa_operand
;
660 enum gimple_code code
= gimple_code (stmt
);
662 /* This function appears to be called only for assignments, calls,
663 conditionals, and switches, due to the logic in visit_stmt. */
664 gcc_assert (code
== GIMPLE_ASSIGN
665 || code
== GIMPLE_CALL
666 || code
== GIMPLE_COND
667 || code
== GIMPLE_SWITCH
);
669 /* If the statement has volatile operands, it won't fold to a
671 if (gimple_has_volatile_ops (stmt
))
674 /* Arrive here for more complex cases. */
675 has_constant_operand
= false;
676 has_undefined_operand
= false;
677 all_undefined_operands
= true;
678 has_nsa_operand
= false;
679 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, iter
, SSA_OP_USE
)
681 ccp_prop_value_t
*val
= get_value (use
);
683 if (val
->lattice_val
== UNDEFINED
)
684 has_undefined_operand
= true;
686 all_undefined_operands
= false;
688 if (val
->lattice_val
== CONSTANT
)
689 has_constant_operand
= true;
691 if (SSA_NAME_IS_DEFAULT_DEF (use
)
692 || !prop_simulate_again_p (SSA_NAME_DEF_STMT (use
)))
693 has_nsa_operand
= true;
696 /* There may be constants in regular rhs operands. For calls we
697 have to ignore lhs, fndecl and static chain, otherwise only
699 for (i
= (is_gimple_call (stmt
) ? 2 : 0) + gimple_has_lhs (stmt
);
700 i
< gimple_num_ops (stmt
); ++i
)
702 tree op
= gimple_op (stmt
, i
);
703 if (!op
|| TREE_CODE (op
) == SSA_NAME
)
705 if (is_gimple_min_invariant (op
))
706 has_constant_operand
= true;
709 if (has_constant_operand
)
710 all_undefined_operands
= false;
712 if (has_undefined_operand
713 && code
== GIMPLE_CALL
714 && gimple_call_internal_p (stmt
))
715 switch (gimple_call_internal_fn (stmt
))
717 /* These 3 builtins use the first argument just as a magic
718 way how to find out a decl uid. */
719 case IFN_GOMP_SIMD_LANE
:
720 case IFN_GOMP_SIMD_VF
:
721 case IFN_GOMP_SIMD_LAST_LANE
:
722 has_undefined_operand
= false;
728 /* If the operation combines operands like COMPLEX_EXPR make sure to
729 not mark the result UNDEFINED if only one part of the result is
731 if (has_undefined_operand
&& all_undefined_operands
)
733 else if (code
== GIMPLE_ASSIGN
&& has_undefined_operand
)
735 switch (gimple_assign_rhs_code (stmt
))
737 /* Unary operators are handled with all_undefined_operands. */
740 case POINTER_PLUS_EXPR
:
741 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected.
742 Not bitwise operators, one VARYING operand may specify the
743 result completely. Not logical operators for the same reason.
744 Not COMPLEX_EXPR as one VARYING operand makes the result partly
745 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because
746 the undefined operand may be promoted. */
750 /* If any part of an address is UNDEFINED, like the index
751 of an ARRAY_EXPR, then treat the result as UNDEFINED. */
758 /* If there was an UNDEFINED operand but the result may be not UNDEFINED
759 fall back to CONSTANT. During iteration UNDEFINED may still drop
761 if (has_undefined_operand
)
764 /* We do not consider virtual operands here -- load from read-only
765 memory may have only VARYING virtual operands, but still be
766 constant. Also we can combine the stmt with definitions from
767 operands whose definitions are not simulated again. */
768 if (has_constant_operand
770 || gimple_references_memory_p (stmt
))
776 /* Returns true if STMT cannot be constant. */
779 surely_varying_stmt_p (gimple
*stmt
)
781 /* If the statement has operands that we cannot handle, it cannot be
783 if (gimple_has_volatile_ops (stmt
))
786 /* If it is a call and does not return a value or is not a
787 builtin and not an indirect call or a call to function with
788 assume_aligned/alloc_align attribute, it is varying. */
789 if (is_gimple_call (stmt
))
791 tree fndecl
, fntype
= gimple_call_fntype (stmt
);
792 if (!gimple_call_lhs (stmt
)
793 || ((fndecl
= gimple_call_fndecl (stmt
)) != NULL_TREE
794 && !DECL_BUILT_IN (fndecl
)
795 && !lookup_attribute ("assume_aligned",
796 TYPE_ATTRIBUTES (fntype
))
797 && !lookup_attribute ("alloc_align",
798 TYPE_ATTRIBUTES (fntype
))))
802 /* Any other store operation is not interesting. */
803 else if (gimple_vdef (stmt
))
806 /* Anything other than assignments and conditional jumps are not
807 interesting for CCP. */
808 if (gimple_code (stmt
) != GIMPLE_ASSIGN
809 && gimple_code (stmt
) != GIMPLE_COND
810 && gimple_code (stmt
) != GIMPLE_SWITCH
811 && gimple_code (stmt
) != GIMPLE_CALL
)
817 /* Initialize local data structures for CCP. */
820 ccp_initialize (void)
824 n_const_val
= num_ssa_names
;
825 const_val
= XCNEWVEC (ccp_prop_value_t
, n_const_val
);
827 /* Initialize simulation flags for PHI nodes and statements. */
828 FOR_EACH_BB_FN (bb
, cfun
)
830 gimple_stmt_iterator i
;
832 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); gsi_next (&i
))
834 gimple
*stmt
= gsi_stmt (i
);
837 /* If the statement is a control insn, then we do not
838 want to avoid simulating the statement once. Failure
839 to do so means that those edges will never get added. */
840 if (stmt_ends_bb_p (stmt
))
843 is_varying
= surely_varying_stmt_p (stmt
);
850 /* If the statement will not produce a constant, mark
851 all its outputs VARYING. */
852 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
853 set_value_varying (def
);
855 prop_set_simulate_again (stmt
, !is_varying
);
859 /* Now process PHI nodes. We never clear the simulate_again flag on
860 phi nodes, since we do not know which edges are executable yet,
861 except for phi nodes for virtual operands when we do not do store ccp. */
862 FOR_EACH_BB_FN (bb
, cfun
)
866 for (i
= gsi_start_phis (bb
); !gsi_end_p (i
); gsi_next (&i
))
868 gphi
*phi
= i
.phi ();
870 if (virtual_operand_p (gimple_phi_result (phi
)))
871 prop_set_simulate_again (phi
, false);
873 prop_set_simulate_again (phi
, true);
878 /* Debug count support. Reset the values of ssa names
879 VARYING when the total number ssa names analyzed is
880 beyond the debug count specified. */
886 for (i
= 0; i
< num_ssa_names
; i
++)
890 const_val
[i
].lattice_val
= VARYING
;
891 const_val
[i
].mask
= -1;
892 const_val
[i
].value
= NULL_TREE
;
898 /* Do final substitution of propagated values, cleanup the flowgraph and
899 free allocated storage.
901 Return TRUE when something was optimized. */
906 bool something_changed
;
911 /* Derive alignment and misalignment information from partially
912 constant pointers in the lattice or nonzero bits from partially
913 constant integers. */
914 for (i
= 1; i
< num_ssa_names
; ++i
)
916 tree name
= ssa_name (i
);
917 ccp_prop_value_t
*val
;
918 unsigned int tem
, align
;
921 || (!POINTER_TYPE_P (TREE_TYPE (name
))
922 && (!INTEGRAL_TYPE_P (TREE_TYPE (name
))
923 /* Don't record nonzero bits before IPA to avoid
924 using too much memory. */
925 || first_pass_instance
)))
928 val
= get_value (name
);
929 if (val
->lattice_val
!= CONSTANT
930 || TREE_CODE (val
->value
) != INTEGER_CST
)
933 if (POINTER_TYPE_P (TREE_TYPE (name
)))
935 /* Trailing mask bits specify the alignment, trailing value
936 bits the misalignment. */
937 tem
= val
->mask
.to_uhwi ();
938 align
= (tem
& -tem
);
940 set_ptr_info_alignment (get_ptr_info (name
), align
,
941 (TREE_INT_CST_LOW (val
->value
)
946 unsigned int precision
= TYPE_PRECISION (TREE_TYPE (val
->value
));
947 wide_int nonzero_bits
= wide_int::from (val
->mask
, precision
,
948 UNSIGNED
) | val
->value
;
949 nonzero_bits
&= get_nonzero_bits (name
);
950 set_nonzero_bits (name
, nonzero_bits
);
954 /* Perform substitutions based on the known constant values. */
955 something_changed
= substitute_and_fold (get_constant_value
,
956 ccp_fold_stmt
, true);
960 return something_changed
;;
964 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
967 any M UNDEFINED = any
968 any M VARYING = VARYING
969 Ci M Cj = Ci if (i == j)
970 Ci M Cj = VARYING if (i != j)
974 ccp_lattice_meet (ccp_prop_value_t
*val1
, ccp_prop_value_t
*val2
)
976 if (val1
->lattice_val
== UNDEFINED
977 /* For UNDEFINED M SSA we can't always SSA because its definition
978 may not dominate the PHI node. Doing optimistic copy propagation
979 also causes a lot of gcc.dg/uninit-pred*.c FAILs. */
980 && (val2
->lattice_val
!= CONSTANT
981 || TREE_CODE (val2
->value
) != SSA_NAME
))
983 /* UNDEFINED M any = any */
986 else if (val2
->lattice_val
== UNDEFINED
988 && (val1
->lattice_val
!= CONSTANT
989 || TREE_CODE (val1
->value
) != SSA_NAME
))
991 /* any M UNDEFINED = any
992 Nothing to do. VAL1 already contains the value we want. */
995 else if (val1
->lattice_val
== VARYING
996 || val2
->lattice_val
== VARYING
)
998 /* any M VARYING = VARYING. */
999 val1
->lattice_val
= VARYING
;
1001 val1
->value
= NULL_TREE
;
1003 else if (val1
->lattice_val
== CONSTANT
1004 && val2
->lattice_val
== CONSTANT
1005 && TREE_CODE (val1
->value
) == INTEGER_CST
1006 && TREE_CODE (val2
->value
) == INTEGER_CST
)
1008 /* Ci M Cj = Ci if (i == j)
1009 Ci M Cj = VARYING if (i != j)
1011 For INTEGER_CSTs mask unequal bits. If no equal bits remain,
1013 val1
->mask
= (val1
->mask
| val2
->mask
1014 | (wi::to_widest (val1
->value
)
1015 ^ wi::to_widest (val2
->value
)));
1016 if (wi::sext (val1
->mask
, TYPE_PRECISION (TREE_TYPE (val1
->value
))) == -1)
1018 val1
->lattice_val
= VARYING
;
1019 val1
->value
= NULL_TREE
;
1022 else if (val1
->lattice_val
== CONSTANT
1023 && val2
->lattice_val
== CONSTANT
1024 && operand_equal_p (val1
->value
, val2
->value
, 0))
1026 /* Ci M Cj = Ci if (i == j)
1027 Ci M Cj = VARYING if (i != j)
1029 VAL1 already contains the value we want for equivalent values. */
1031 else if (val1
->lattice_val
== CONSTANT
1032 && val2
->lattice_val
== CONSTANT
1033 && (TREE_CODE (val1
->value
) == ADDR_EXPR
1034 || TREE_CODE (val2
->value
) == ADDR_EXPR
))
1036 /* When not equal addresses are involved try meeting for
1038 ccp_prop_value_t tem
= *val2
;
1039 if (TREE_CODE (val1
->value
) == ADDR_EXPR
)
1040 *val1
= get_value_for_expr (val1
->value
, true);
1041 if (TREE_CODE (val2
->value
) == ADDR_EXPR
)
1042 tem
= get_value_for_expr (val2
->value
, true);
1043 ccp_lattice_meet (val1
, &tem
);
1047 /* Any other combination is VARYING. */
1048 val1
->lattice_val
= VARYING
;
1050 val1
->value
= NULL_TREE
;
1055 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
1056 lattice values to determine PHI_NODE's lattice value. The value of a
1057 PHI node is determined calling ccp_lattice_meet with all the arguments
1058 of the PHI node that are incoming via executable edges. */
1060 static enum ssa_prop_result
1061 ccp_visit_phi_node (gphi
*phi
)
1064 ccp_prop_value_t new_val
;
1066 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1068 fprintf (dump_file
, "\nVisiting PHI node: ");
1069 print_gimple_stmt (dump_file
, phi
, 0, dump_flags
);
1072 new_val
.lattice_val
= UNDEFINED
;
1073 new_val
.value
= NULL_TREE
;
1077 bool non_exec_edge
= false;
1078 for (i
= 0; i
< gimple_phi_num_args (phi
); i
++)
1080 /* Compute the meet operator over all the PHI arguments flowing
1081 through executable edges. */
1082 edge e
= gimple_phi_arg_edge (phi
, i
);
1084 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1087 "\n Argument #%d (%d -> %d %sexecutable)\n",
1088 i
, e
->src
->index
, e
->dest
->index
,
1089 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
1092 /* If the incoming edge is executable, Compute the meet operator for
1093 the existing value of the PHI node and the current PHI argument. */
1094 if (e
->flags
& EDGE_EXECUTABLE
)
1096 tree arg
= gimple_phi_arg (phi
, i
)->def
;
1097 ccp_prop_value_t arg_val
= get_value_for_expr (arg
, false);
1105 ccp_lattice_meet (&new_val
, &arg_val
);
1107 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1109 fprintf (dump_file
, "\t");
1110 print_generic_expr (dump_file
, arg
, dump_flags
);
1111 dump_lattice_value (dump_file
, "\tValue: ", arg_val
);
1112 fprintf (dump_file
, "\n");
1115 if (new_val
.lattice_val
== VARYING
)
1119 non_exec_edge
= true;
1122 /* In case there were non-executable edges and the value is a copy
1123 make sure its definition dominates the PHI node. */
1125 && new_val
.lattice_val
== CONSTANT
1126 && TREE_CODE (new_val
.value
) == SSA_NAME
1127 && ! SSA_NAME_IS_DEFAULT_DEF (new_val
.value
)
1128 && ! dominated_by_p (CDI_DOMINATORS
, gimple_bb (phi
),
1129 gimple_bb (SSA_NAME_DEF_STMT (new_val
.value
))))
1131 new_val
.lattice_val
= VARYING
;
1132 new_val
.value
= NULL_TREE
;
1136 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1138 dump_lattice_value (dump_file
, "\n PHI node value: ", new_val
);
1139 fprintf (dump_file
, "\n\n");
1142 /* Make the transition to the new value. */
1143 if (set_lattice_value (gimple_phi_result (phi
), &new_val
))
1145 if (new_val
.lattice_val
== VARYING
)
1146 return SSA_PROP_VARYING
;
1148 return SSA_PROP_INTERESTING
;
1151 return SSA_PROP_NOT_INTERESTING
;
1154 /* Return the constant value for OP or OP otherwise. */
1157 valueize_op (tree op
)
1159 if (TREE_CODE (op
) == SSA_NAME
)
1161 tree tem
= get_constant_value (op
);
1168 /* Return the constant value for OP, but signal to not follow SSA
1169 edges if the definition may be simulated again. */
1172 valueize_op_1 (tree op
)
1174 if (TREE_CODE (op
) == SSA_NAME
)
1176 /* If the definition may be simulated again we cannot follow
1177 this SSA edge as the SSA propagator does not necessarily
1178 re-visit the use. */
1179 gimple
*def_stmt
= SSA_NAME_DEF_STMT (op
);
1180 if (!gimple_nop_p (def_stmt
)
1181 && prop_simulate_again_p (def_stmt
))
1183 tree tem
= get_constant_value (op
);
1190 /* CCP specific front-end to the non-destructive constant folding
1193 Attempt to simplify the RHS of STMT knowing that one or more
1194 operands are constants.
1196 If simplification is possible, return the simplified RHS,
1197 otherwise return the original RHS or NULL_TREE. */
1200 ccp_fold (gimple
*stmt
)
1202 location_t loc
= gimple_location (stmt
);
1203 switch (gimple_code (stmt
))
1207 /* Handle comparison operators that can appear in GIMPLE form. */
1208 tree op0
= valueize_op (gimple_cond_lhs (stmt
));
1209 tree op1
= valueize_op (gimple_cond_rhs (stmt
));
1210 enum tree_code code
= gimple_cond_code (stmt
);
1211 return fold_binary_loc (loc
, code
, boolean_type_node
, op0
, op1
);
1216 /* Return the constant switch index. */
1217 return valueize_op (gimple_switch_index (as_a
<gswitch
*> (stmt
)));
1222 return gimple_fold_stmt_to_constant_1 (stmt
,
1223 valueize_op
, valueize_op_1
);
1230 /* Apply the operation CODE in type TYPE to the value, mask pair
1231 RVAL and RMASK representing a value of type RTYPE and set
1232 the value, mask pair *VAL and *MASK to the result. */
1235 bit_value_unop_1 (enum tree_code code
, tree type
,
1236 widest_int
*val
, widest_int
*mask
,
1237 tree rtype
, const widest_int
&rval
, const widest_int
&rmask
)
1248 widest_int temv
, temm
;
1249 /* Return ~rval + 1. */
1250 bit_value_unop_1 (BIT_NOT_EXPR
, type
, &temv
, &temm
, type
, rval
, rmask
);
1251 bit_value_binop_1 (PLUS_EXPR
, type
, val
, mask
,
1252 type
, temv
, temm
, type
, 1, 0);
1260 /* First extend mask and value according to the original type. */
1261 sgn
= TYPE_SIGN (rtype
);
1262 *mask
= wi::ext (rmask
, TYPE_PRECISION (rtype
), sgn
);
1263 *val
= wi::ext (rval
, TYPE_PRECISION (rtype
), sgn
);
1265 /* Then extend mask and value according to the target type. */
1266 sgn
= TYPE_SIGN (type
);
1267 *mask
= wi::ext (*mask
, TYPE_PRECISION (type
), sgn
);
1268 *val
= wi::ext (*val
, TYPE_PRECISION (type
), sgn
);
1278 /* Apply the operation CODE in type TYPE to the value, mask pairs
1279 R1VAL, R1MASK and R2VAL, R2MASK representing a values of type R1TYPE
1280 and R2TYPE and set the value, mask pair *VAL and *MASK to the result. */
1283 bit_value_binop_1 (enum tree_code code
, tree type
,
1284 widest_int
*val
, widest_int
*mask
,
1285 tree r1type
, const widest_int
&r1val
,
1286 const widest_int
&r1mask
, tree r2type
,
1287 const widest_int
&r2val
, const widest_int
&r2mask
)
1289 signop sgn
= TYPE_SIGN (type
);
1290 int width
= TYPE_PRECISION (type
);
1291 bool swap_p
= false;
1293 /* Assume we'll get a constant result. Use an initial non varying
1294 value, we fall back to varying in the end if necessary. */
1300 /* The mask is constant where there is a known not
1301 set bit, (m1 | m2) & ((v1 | m1) & (v2 | m2)) */
1302 *mask
= (r1mask
| r2mask
) & (r1val
| r1mask
) & (r2val
| r2mask
);
1303 *val
= r1val
& r2val
;
1307 /* The mask is constant where there is a known
1308 set bit, (m1 | m2) & ~((v1 & ~m1) | (v2 & ~m2)). */
1309 *mask
= (r1mask
| r2mask
)
1310 .and_not (r1val
.and_not (r1mask
) | r2val
.and_not (r2mask
));
1311 *val
= r1val
| r2val
;
1316 *mask
= r1mask
| r2mask
;
1317 *val
= r1val
^ r2val
;
1324 widest_int shift
= r2val
;
1332 if (wi::neg_p (shift
))
1335 if (code
== RROTATE_EXPR
)
1336 code
= LROTATE_EXPR
;
1338 code
= RROTATE_EXPR
;
1340 if (code
== RROTATE_EXPR
)
1342 *mask
= wi::rrotate (r1mask
, shift
, width
);
1343 *val
= wi::rrotate (r1val
, shift
, width
);
1347 *mask
= wi::lrotate (r1mask
, shift
, width
);
1348 *val
= wi::lrotate (r1val
, shift
, width
);
1356 /* ??? We can handle partially known shift counts if we know
1357 its sign. That way we can tell that (x << (y | 8)) & 255
1361 widest_int shift
= r2val
;
1369 if (wi::neg_p (shift
))
1372 if (code
== RSHIFT_EXPR
)
1377 if (code
== RSHIFT_EXPR
)
1379 *mask
= wi::rshift (wi::ext (r1mask
, width
, sgn
), shift
, sgn
);
1380 *val
= wi::rshift (wi::ext (r1val
, width
, sgn
), shift
, sgn
);
1384 *mask
= wi::ext (wi::lshift (r1mask
, shift
), width
, sgn
);
1385 *val
= wi::ext (wi::lshift (r1val
, shift
), width
, sgn
);
1392 case POINTER_PLUS_EXPR
:
1394 /* Do the addition with unknown bits set to zero, to give carry-ins of
1395 zero wherever possible. */
1396 widest_int lo
= r1val
.and_not (r1mask
) + r2val
.and_not (r2mask
);
1397 lo
= wi::ext (lo
, width
, sgn
);
1398 /* Do the addition with unknown bits set to one, to give carry-ins of
1399 one wherever possible. */
1400 widest_int hi
= (r1val
| r1mask
) + (r2val
| r2mask
);
1401 hi
= wi::ext (hi
, width
, sgn
);
1402 /* Each bit in the result is known if (a) the corresponding bits in
1403 both inputs are known, and (b) the carry-in to that bit position
1404 is known. We can check condition (b) by seeing if we got the same
1405 result with minimised carries as with maximised carries. */
1406 *mask
= r1mask
| r2mask
| (lo
^ hi
);
1407 *mask
= wi::ext (*mask
, width
, sgn
);
1408 /* It shouldn't matter whether we choose lo or hi here. */
1415 widest_int temv
, temm
;
1416 bit_value_unop_1 (NEGATE_EXPR
, r2type
, &temv
, &temm
,
1417 r2type
, r2val
, r2mask
);
1418 bit_value_binop_1 (PLUS_EXPR
, type
, val
, mask
,
1419 r1type
, r1val
, r1mask
,
1420 r2type
, temv
, temm
);
1426 /* Just track trailing zeros in both operands and transfer
1427 them to the other. */
1428 int r1tz
= wi::ctz (r1val
| r1mask
);
1429 int r2tz
= wi::ctz (r2val
| r2mask
);
1430 if (r1tz
+ r2tz
>= width
)
1435 else if (r1tz
+ r2tz
> 0)
1437 *mask
= wi::ext (wi::mask
<widest_int
> (r1tz
+ r2tz
, true),
1447 widest_int m
= r1mask
| r2mask
;
1448 if (r1val
.and_not (m
) != r2val
.and_not (m
))
1451 *val
= ((code
== EQ_EXPR
) ? 0 : 1);
1455 /* We know the result of a comparison is always one or zero. */
1465 code
= swap_tree_comparison (code
);
1472 const widest_int
&o1val
= swap_p
? r2val
: r1val
;
1473 const widest_int
&o1mask
= swap_p
? r2mask
: r1mask
;
1474 const widest_int
&o2val
= swap_p
? r1val
: r2val
;
1475 const widest_int
&o2mask
= swap_p
? r1mask
: r2mask
;
1477 /* If the most significant bits are not known we know nothing. */
1478 if (wi::neg_p (o1mask
) || wi::neg_p (o2mask
))
1481 /* For comparisons the signedness is in the comparison operands. */
1482 sgn
= TYPE_SIGN (r1type
);
1484 /* If we know the most significant bits we know the values
1485 value ranges by means of treating varying bits as zero
1486 or one. Do a cross comparison of the max/min pairs. */
1487 maxmin
= wi::cmp (o1val
| o1mask
, o2val
.and_not (o2mask
), sgn
);
1488 minmax
= wi::cmp (o1val
.and_not (o1mask
), o2val
| o2mask
, sgn
);
1489 if (maxmin
< 0) /* o1 is less than o2. */
1494 else if (minmax
> 0) /* o1 is not less or equal to o2. */
1499 else if (maxmin
== minmax
) /* o1 and o2 are equal. */
1501 /* This probably should never happen as we'd have
1502 folded the thing during fully constant value folding. */
1504 *val
= (code
== LE_EXPR
? 1 : 0);
1508 /* We know the result of a comparison is always one or zero. */
1519 /* Return the propagation value when applying the operation CODE to
1520 the value RHS yielding type TYPE. */
1522 static ccp_prop_value_t
1523 bit_value_unop (enum tree_code code
, tree type
, tree rhs
)
1525 ccp_prop_value_t rval
= get_value_for_expr (rhs
, true);
1526 widest_int value
, mask
;
1527 ccp_prop_value_t val
;
1529 if (rval
.lattice_val
== UNDEFINED
)
1532 gcc_assert ((rval
.lattice_val
== CONSTANT
1533 && TREE_CODE (rval
.value
) == INTEGER_CST
)
1534 || wi::sext (rval
.mask
, TYPE_PRECISION (TREE_TYPE (rhs
))) == -1);
1535 bit_value_unop_1 (code
, type
, &value
, &mask
,
1536 TREE_TYPE (rhs
), value_to_wide_int (rval
), rval
.mask
);
1537 if (wi::sext (mask
, TYPE_PRECISION (type
)) != -1)
1539 val
.lattice_val
= CONSTANT
;
1541 /* ??? Delay building trees here. */
1542 val
.value
= wide_int_to_tree (type
, value
);
1546 val
.lattice_val
= VARYING
;
1547 val
.value
= NULL_TREE
;
1553 /* Return the propagation value when applying the operation CODE to
1554 the values RHS1 and RHS2 yielding type TYPE. */
1556 static ccp_prop_value_t
1557 bit_value_binop (enum tree_code code
, tree type
, tree rhs1
, tree rhs2
)
1559 ccp_prop_value_t r1val
= get_value_for_expr (rhs1
, true);
1560 ccp_prop_value_t r2val
= get_value_for_expr (rhs2
, true);
1561 widest_int value
, mask
;
1562 ccp_prop_value_t val
;
1564 if (r1val
.lattice_val
== UNDEFINED
1565 || r2val
.lattice_val
== UNDEFINED
)
1567 val
.lattice_val
= VARYING
;
1568 val
.value
= NULL_TREE
;
1573 gcc_assert ((r1val
.lattice_val
== CONSTANT
1574 && TREE_CODE (r1val
.value
) == INTEGER_CST
)
1575 || wi::sext (r1val
.mask
,
1576 TYPE_PRECISION (TREE_TYPE (rhs1
))) == -1);
1577 gcc_assert ((r2val
.lattice_val
== CONSTANT
1578 && TREE_CODE (r2val
.value
) == INTEGER_CST
)
1579 || wi::sext (r2val
.mask
,
1580 TYPE_PRECISION (TREE_TYPE (rhs2
))) == -1);
1581 bit_value_binop_1 (code
, type
, &value
, &mask
,
1582 TREE_TYPE (rhs1
), value_to_wide_int (r1val
), r1val
.mask
,
1583 TREE_TYPE (rhs2
), value_to_wide_int (r2val
), r2val
.mask
);
1584 if (wi::sext (mask
, TYPE_PRECISION (type
)) != -1)
1586 val
.lattice_val
= CONSTANT
;
1588 /* ??? Delay building trees here. */
1589 val
.value
= wide_int_to_tree (type
, value
);
1593 val
.lattice_val
= VARYING
;
1594 val
.value
= NULL_TREE
;
1600 /* Return the propagation value for __builtin_assume_aligned
1601 and functions with assume_aligned or alloc_aligned attribute.
1602 For __builtin_assume_aligned, ATTR is NULL_TREE,
1603 for assume_aligned attribute ATTR is non-NULL and ALLOC_ALIGNED
1604 is false, for alloc_aligned attribute ATTR is non-NULL and
1605 ALLOC_ALIGNED is true. */
1607 static ccp_prop_value_t
1608 bit_value_assume_aligned (gimple
*stmt
, tree attr
, ccp_prop_value_t ptrval
,
1611 tree align
, misalign
= NULL_TREE
, type
;
1612 unsigned HOST_WIDE_INT aligni
, misaligni
= 0;
1613 ccp_prop_value_t alignval
;
1614 widest_int value
, mask
;
1615 ccp_prop_value_t val
;
1617 if (attr
== NULL_TREE
)
1619 tree ptr
= gimple_call_arg (stmt
, 0);
1620 type
= TREE_TYPE (ptr
);
1621 ptrval
= get_value_for_expr (ptr
, true);
1625 tree lhs
= gimple_call_lhs (stmt
);
1626 type
= TREE_TYPE (lhs
);
1629 if (ptrval
.lattice_val
== UNDEFINED
)
1631 gcc_assert ((ptrval
.lattice_val
== CONSTANT
1632 && TREE_CODE (ptrval
.value
) == INTEGER_CST
)
1633 || wi::sext (ptrval
.mask
, TYPE_PRECISION (type
)) == -1);
1634 if (attr
== NULL_TREE
)
1636 /* Get aligni and misaligni from __builtin_assume_aligned. */
1637 align
= gimple_call_arg (stmt
, 1);
1638 if (!tree_fits_uhwi_p (align
))
1640 aligni
= tree_to_uhwi (align
);
1641 if (gimple_call_num_args (stmt
) > 2)
1643 misalign
= gimple_call_arg (stmt
, 2);
1644 if (!tree_fits_uhwi_p (misalign
))
1646 misaligni
= tree_to_uhwi (misalign
);
1651 /* Get aligni and misaligni from assume_aligned or
1652 alloc_align attributes. */
1653 if (TREE_VALUE (attr
) == NULL_TREE
)
1655 attr
= TREE_VALUE (attr
);
1656 align
= TREE_VALUE (attr
);
1657 if (!tree_fits_uhwi_p (align
))
1659 aligni
= tree_to_uhwi (align
);
1662 if (aligni
== 0 || aligni
> gimple_call_num_args (stmt
))
1664 align
= gimple_call_arg (stmt
, aligni
- 1);
1665 if (!tree_fits_uhwi_p (align
))
1667 aligni
= tree_to_uhwi (align
);
1669 else if (TREE_CHAIN (attr
) && TREE_VALUE (TREE_CHAIN (attr
)))
1671 misalign
= TREE_VALUE (TREE_CHAIN (attr
));
1672 if (!tree_fits_uhwi_p (misalign
))
1674 misaligni
= tree_to_uhwi (misalign
);
1677 if (aligni
<= 1 || (aligni
& (aligni
- 1)) != 0 || misaligni
>= aligni
)
1680 align
= build_int_cst_type (type
, -aligni
);
1681 alignval
= get_value_for_expr (align
, true);
1682 bit_value_binop_1 (BIT_AND_EXPR
, type
, &value
, &mask
,
1683 type
, value_to_wide_int (ptrval
), ptrval
.mask
,
1684 type
, value_to_wide_int (alignval
), alignval
.mask
);
1685 if (wi::sext (mask
, TYPE_PRECISION (type
)) != -1)
1687 val
.lattice_val
= CONSTANT
;
1689 gcc_assert ((mask
.to_uhwi () & (aligni
- 1)) == 0);
1690 gcc_assert ((value
.to_uhwi () & (aligni
- 1)) == 0);
1692 /* ??? Delay building trees here. */
1693 val
.value
= wide_int_to_tree (type
, value
);
1697 val
.lattice_val
= VARYING
;
1698 val
.value
= NULL_TREE
;
1704 /* Evaluate statement STMT.
1705 Valid only for assignments, calls, conditionals, and switches. */
1707 static ccp_prop_value_t
1708 evaluate_stmt (gimple
*stmt
)
1710 ccp_prop_value_t val
;
1711 tree simplified
= NULL_TREE
;
1712 ccp_lattice_t likelyvalue
= likely_value (stmt
);
1713 bool is_constant
= false;
1716 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1718 fprintf (dump_file
, "which is likely ");
1719 switch (likelyvalue
)
1722 fprintf (dump_file
, "CONSTANT");
1725 fprintf (dump_file
, "UNDEFINED");
1728 fprintf (dump_file
, "VARYING");
1732 fprintf (dump_file
, "\n");
1735 /* If the statement is likely to have a CONSTANT result, then try
1736 to fold the statement to determine the constant value. */
1737 /* FIXME. This is the only place that we call ccp_fold.
1738 Since likely_value never returns CONSTANT for calls, we will
1739 not attempt to fold them, including builtins that may profit. */
1740 if (likelyvalue
== CONSTANT
)
1742 fold_defer_overflow_warnings ();
1743 simplified
= ccp_fold (stmt
);
1744 if (simplified
&& TREE_CODE (simplified
) == SSA_NAME
)
1746 val
= *get_value (simplified
);
1747 if (val
.lattice_val
!= VARYING
)
1749 fold_undefer_overflow_warnings (true, stmt
, 0);
1753 is_constant
= simplified
&& is_gimple_min_invariant (simplified
);
1754 fold_undefer_overflow_warnings (is_constant
, stmt
, 0);
1757 /* The statement produced a constant value. */
1758 val
.lattice_val
= CONSTANT
;
1759 val
.value
= simplified
;
1764 /* If the statement is likely to have a VARYING result, then do not
1765 bother folding the statement. */
1766 else if (likelyvalue
== VARYING
)
1768 enum gimple_code code
= gimple_code (stmt
);
1769 if (code
== GIMPLE_ASSIGN
)
1771 enum tree_code subcode
= gimple_assign_rhs_code (stmt
);
1773 /* Other cases cannot satisfy is_gimple_min_invariant
1775 if (get_gimple_rhs_class (subcode
) == GIMPLE_SINGLE_RHS
)
1776 simplified
= gimple_assign_rhs1 (stmt
);
1778 else if (code
== GIMPLE_SWITCH
)
1779 simplified
= gimple_switch_index (as_a
<gswitch
*> (stmt
));
1781 /* These cannot satisfy is_gimple_min_invariant without folding. */
1782 gcc_assert (code
== GIMPLE_CALL
|| code
== GIMPLE_COND
);
1783 is_constant
= simplified
&& is_gimple_min_invariant (simplified
);
1786 /* The statement produced a constant value. */
1787 val
.lattice_val
= CONSTANT
;
1788 val
.value
= simplified
;
1792 /* If the statement result is likely UNDEFINED, make it so. */
1793 else if (likelyvalue
== UNDEFINED
)
1795 val
.lattice_val
= UNDEFINED
;
1796 val
.value
= NULL_TREE
;
1801 /* Resort to simplification for bitwise tracking. */
1802 if (flag_tree_bit_ccp
1803 && (likelyvalue
== CONSTANT
|| is_gimple_call (stmt
)
1804 || (gimple_assign_single_p (stmt
)
1805 && gimple_assign_rhs_code (stmt
) == ADDR_EXPR
))
1808 enum gimple_code code
= gimple_code (stmt
);
1809 val
.lattice_val
= VARYING
;
1810 val
.value
= NULL_TREE
;
1812 if (code
== GIMPLE_ASSIGN
)
1814 enum tree_code subcode
= gimple_assign_rhs_code (stmt
);
1815 tree rhs1
= gimple_assign_rhs1 (stmt
);
1816 tree lhs
= gimple_assign_lhs (stmt
);
1817 if ((INTEGRAL_TYPE_P (TREE_TYPE (lhs
))
1818 || POINTER_TYPE_P (TREE_TYPE (lhs
)))
1819 && (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1820 || POINTER_TYPE_P (TREE_TYPE (rhs1
))))
1821 switch (get_gimple_rhs_class (subcode
))
1823 case GIMPLE_SINGLE_RHS
:
1824 val
= get_value_for_expr (rhs1
, true);
1827 case GIMPLE_UNARY_RHS
:
1828 val
= bit_value_unop (subcode
, TREE_TYPE (lhs
), rhs1
);
1831 case GIMPLE_BINARY_RHS
:
1832 val
= bit_value_binop (subcode
, TREE_TYPE (lhs
), rhs1
,
1833 gimple_assign_rhs2 (stmt
));
1839 else if (code
== GIMPLE_COND
)
1841 enum tree_code code
= gimple_cond_code (stmt
);
1842 tree rhs1
= gimple_cond_lhs (stmt
);
1843 tree rhs2
= gimple_cond_rhs (stmt
);
1844 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1845 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1846 val
= bit_value_binop (code
, TREE_TYPE (rhs1
), rhs1
, rhs2
);
1848 else if (gimple_call_builtin_p (stmt
, BUILT_IN_NORMAL
))
1850 tree fndecl
= gimple_call_fndecl (stmt
);
1851 switch (DECL_FUNCTION_CODE (fndecl
))
1853 case BUILT_IN_MALLOC
:
1854 case BUILT_IN_REALLOC
:
1855 case BUILT_IN_CALLOC
:
1856 case BUILT_IN_STRDUP
:
1857 case BUILT_IN_STRNDUP
:
1858 val
.lattice_val
= CONSTANT
;
1859 val
.value
= build_int_cst (TREE_TYPE (gimple_get_lhs (stmt
)), 0);
1860 val
.mask
= ~((HOST_WIDE_INT
) MALLOC_ABI_ALIGNMENT
1861 / BITS_PER_UNIT
- 1);
1864 case BUILT_IN_ALLOCA
:
1865 case BUILT_IN_ALLOCA_WITH_ALIGN
:
1866 align
= (DECL_FUNCTION_CODE (fndecl
) == BUILT_IN_ALLOCA_WITH_ALIGN
1867 ? TREE_INT_CST_LOW (gimple_call_arg (stmt
, 1))
1868 : BIGGEST_ALIGNMENT
);
1869 val
.lattice_val
= CONSTANT
;
1870 val
.value
= build_int_cst (TREE_TYPE (gimple_get_lhs (stmt
)), 0);
1871 val
.mask
= ~((HOST_WIDE_INT
) align
/ BITS_PER_UNIT
- 1);
1874 /* These builtins return their first argument, unmodified. */
1875 case BUILT_IN_MEMCPY
:
1876 case BUILT_IN_MEMMOVE
:
1877 case BUILT_IN_MEMSET
:
1878 case BUILT_IN_STRCPY
:
1879 case BUILT_IN_STRNCPY
:
1880 case BUILT_IN_MEMCPY_CHK
:
1881 case BUILT_IN_MEMMOVE_CHK
:
1882 case BUILT_IN_MEMSET_CHK
:
1883 case BUILT_IN_STRCPY_CHK
:
1884 case BUILT_IN_STRNCPY_CHK
:
1885 val
= get_value_for_expr (gimple_call_arg (stmt
, 0), true);
1888 case BUILT_IN_ASSUME_ALIGNED
:
1889 val
= bit_value_assume_aligned (stmt
, NULL_TREE
, val
, false);
1892 case BUILT_IN_ALIGNED_ALLOC
:
1894 tree align
= get_constant_value (gimple_call_arg (stmt
, 0));
1896 && tree_fits_uhwi_p (align
))
1898 unsigned HOST_WIDE_INT aligni
= tree_to_uhwi (align
);
1900 /* align must be power-of-two */
1901 && (aligni
& (aligni
- 1)) == 0)
1903 val
.lattice_val
= CONSTANT
;
1904 val
.value
= build_int_cst (ptr_type_node
, 0);
1914 if (is_gimple_call (stmt
) && gimple_call_lhs (stmt
))
1916 tree fntype
= gimple_call_fntype (stmt
);
1919 tree attrs
= lookup_attribute ("assume_aligned",
1920 TYPE_ATTRIBUTES (fntype
));
1922 val
= bit_value_assume_aligned (stmt
, attrs
, val
, false);
1923 attrs
= lookup_attribute ("alloc_align",
1924 TYPE_ATTRIBUTES (fntype
));
1926 val
= bit_value_assume_aligned (stmt
, attrs
, val
, true);
1929 is_constant
= (val
.lattice_val
== CONSTANT
);
1932 if (flag_tree_bit_ccp
1933 && ((is_constant
&& TREE_CODE (val
.value
) == INTEGER_CST
)
1935 && gimple_get_lhs (stmt
)
1936 && TREE_CODE (gimple_get_lhs (stmt
)) == SSA_NAME
)
1938 tree lhs
= gimple_get_lhs (stmt
);
1939 wide_int nonzero_bits
= get_nonzero_bits (lhs
);
1940 if (nonzero_bits
!= -1)
1944 val
.lattice_val
= CONSTANT
;
1945 val
.value
= build_zero_cst (TREE_TYPE (lhs
));
1946 val
.mask
= extend_mask (nonzero_bits
);
1951 if (wi::bit_and_not (val
.value
, nonzero_bits
) != 0)
1952 val
.value
= wide_int_to_tree (TREE_TYPE (lhs
),
1953 nonzero_bits
& val
.value
);
1954 if (nonzero_bits
== 0)
1957 val
.mask
= val
.mask
& extend_mask (nonzero_bits
);
1962 /* The statement produced a nonconstant value. */
1965 /* The statement produced a copy. */
1966 if (simplified
&& TREE_CODE (simplified
) == SSA_NAME
1967 && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (simplified
))
1969 val
.lattice_val
= CONSTANT
;
1970 val
.value
= simplified
;
1973 /* The statement is VARYING. */
1976 val
.lattice_val
= VARYING
;
1977 val
.value
= NULL_TREE
;
1985 typedef hash_table
<nofree_ptr_hash
<gimple
> > gimple_htab
;
1987 /* Given a BUILT_IN_STACK_SAVE value SAVED_VAL, insert a clobber of VAR before
1988 each matching BUILT_IN_STACK_RESTORE. Mark visited phis in VISITED. */
1991 insert_clobber_before_stack_restore (tree saved_val
, tree var
,
1992 gimple_htab
**visited
)
1995 gassign
*clobber_stmt
;
1997 imm_use_iterator iter
;
1998 gimple_stmt_iterator i
;
2001 FOR_EACH_IMM_USE_STMT (stmt
, iter
, saved_val
)
2002 if (gimple_call_builtin_p (stmt
, BUILT_IN_STACK_RESTORE
))
2004 clobber
= build_constructor (TREE_TYPE (var
),
2006 TREE_THIS_VOLATILE (clobber
) = 1;
2007 clobber_stmt
= gimple_build_assign (var
, clobber
);
2009 i
= gsi_for_stmt (stmt
);
2010 gsi_insert_before (&i
, clobber_stmt
, GSI_SAME_STMT
);
2012 else if (gimple_code (stmt
) == GIMPLE_PHI
)
2015 *visited
= new gimple_htab (10);
2017 slot
= (*visited
)->find_slot (stmt
, INSERT
);
2022 insert_clobber_before_stack_restore (gimple_phi_result (stmt
), var
,
2025 else if (gimple_assign_ssa_name_copy_p (stmt
))
2026 insert_clobber_before_stack_restore (gimple_assign_lhs (stmt
), var
,
2028 else if (chkp_gimple_call_builtin_p (stmt
, BUILT_IN_CHKP_BNDRET
))
2031 gcc_assert (is_gimple_debug (stmt
));
2034 /* Advance the iterator to the previous non-debug gimple statement in the same
2035 or dominating basic block. */
2038 gsi_prev_dom_bb_nondebug (gimple_stmt_iterator
*i
)
2042 gsi_prev_nondebug (i
);
2043 while (gsi_end_p (*i
))
2045 dom
= get_immediate_dominator (CDI_DOMINATORS
, i
->bb
);
2046 if (dom
== NULL
|| dom
== ENTRY_BLOCK_PTR_FOR_FN (cfun
))
2049 *i
= gsi_last_bb (dom
);
2053 /* Find a BUILT_IN_STACK_SAVE dominating gsi_stmt (I), and insert
2054 a clobber of VAR before each matching BUILT_IN_STACK_RESTORE.
2056 It is possible that BUILT_IN_STACK_SAVE cannot be find in a dominator when a
2057 previous pass (such as DOM) duplicated it along multiple paths to a BB. In
2058 that case the function gives up without inserting the clobbers. */
2061 insert_clobbers_for_var (gimple_stmt_iterator i
, tree var
)
2065 gimple_htab
*visited
= NULL
;
2067 for (; !gsi_end_p (i
); gsi_prev_dom_bb_nondebug (&i
))
2069 stmt
= gsi_stmt (i
);
2071 if (!gimple_call_builtin_p (stmt
, BUILT_IN_STACK_SAVE
))
2074 saved_val
= gimple_call_lhs (stmt
);
2075 if (saved_val
== NULL_TREE
)
2078 insert_clobber_before_stack_restore (saved_val
, var
, &visited
);
2085 /* Detects a __builtin_alloca_with_align with constant size argument. Declares
2086 fixed-size array and returns the address, if found, otherwise returns
2090 fold_builtin_alloca_with_align (gimple
*stmt
)
2092 unsigned HOST_WIDE_INT size
, threshold
, n_elem
;
2093 tree lhs
, arg
, block
, var
, elem_type
, array_type
;
2096 lhs
= gimple_call_lhs (stmt
);
2097 if (lhs
== NULL_TREE
)
2100 /* Detect constant argument. */
2101 arg
= get_constant_value (gimple_call_arg (stmt
, 0));
2102 if (arg
== NULL_TREE
2103 || TREE_CODE (arg
) != INTEGER_CST
2104 || !tree_fits_uhwi_p (arg
))
2107 size
= tree_to_uhwi (arg
);
2109 /* Heuristic: don't fold large allocas. */
2110 threshold
= (unsigned HOST_WIDE_INT
)PARAM_VALUE (PARAM_LARGE_STACK_FRAME
);
2111 /* In case the alloca is located at function entry, it has the same lifetime
2112 as a declared array, so we allow a larger size. */
2113 block
= gimple_block (stmt
);
2114 if (!(cfun
->after_inlining
2116 && TREE_CODE (BLOCK_SUPERCONTEXT (block
)) == FUNCTION_DECL
))
2118 if (size
> threshold
)
2121 /* Declare array. */
2122 elem_type
= build_nonstandard_integer_type (BITS_PER_UNIT
, 1);
2123 n_elem
= size
* 8 / BITS_PER_UNIT
;
2124 array_type
= build_array_type_nelts (elem_type
, n_elem
);
2125 var
= create_tmp_var (array_type
);
2126 DECL_ALIGN (var
) = TREE_INT_CST_LOW (gimple_call_arg (stmt
, 1));
2128 struct ptr_info_def
*pi
= SSA_NAME_PTR_INFO (lhs
);
2129 if (pi
!= NULL
&& !pi
->pt
.anything
)
2133 singleton_p
= pt_solution_singleton_p (&pi
->pt
, &uid
);
2134 gcc_assert (singleton_p
);
2135 SET_DECL_PT_UID (var
, uid
);
2139 /* Fold alloca to the address of the array. */
2140 return fold_convert (TREE_TYPE (lhs
), build_fold_addr_expr (var
));
2143 /* Fold the stmt at *GSI with CCP specific information that propagating
2144 and regular folding does not catch. */
2147 ccp_fold_stmt (gimple_stmt_iterator
*gsi
)
2149 gimple
*stmt
= gsi_stmt (*gsi
);
2151 switch (gimple_code (stmt
))
2155 gcond
*cond_stmt
= as_a
<gcond
*> (stmt
);
2156 ccp_prop_value_t val
;
2157 /* Statement evaluation will handle type mismatches in constants
2158 more gracefully than the final propagation. This allows us to
2159 fold more conditionals here. */
2160 val
= evaluate_stmt (stmt
);
2161 if (val
.lattice_val
!= CONSTANT
2167 fprintf (dump_file
, "Folding predicate ");
2168 print_gimple_expr (dump_file
, stmt
, 0, 0);
2169 fprintf (dump_file
, " to ");
2170 print_generic_expr (dump_file
, val
.value
, 0);
2171 fprintf (dump_file
, "\n");
2174 if (integer_zerop (val
.value
))
2175 gimple_cond_make_false (cond_stmt
);
2177 gimple_cond_make_true (cond_stmt
);
2184 tree lhs
= gimple_call_lhs (stmt
);
2185 int flags
= gimple_call_flags (stmt
);
2188 bool changed
= false;
2191 /* If the call was folded into a constant make sure it goes
2192 away even if we cannot propagate into all uses because of
2195 && TREE_CODE (lhs
) == SSA_NAME
2196 && (val
= get_constant_value (lhs
))
2197 /* Don't optimize away calls that have side-effects. */
2198 && (flags
& (ECF_CONST
|ECF_PURE
)) != 0
2199 && (flags
& ECF_LOOPING_CONST_OR_PURE
) == 0)
2201 tree new_rhs
= unshare_expr (val
);
2203 if (!useless_type_conversion_p (TREE_TYPE (lhs
),
2204 TREE_TYPE (new_rhs
)))
2205 new_rhs
= fold_convert (TREE_TYPE (lhs
), new_rhs
);
2206 res
= update_call_from_tree (gsi
, new_rhs
);
2211 /* Internal calls provide no argument types, so the extra laxity
2212 for normal calls does not apply. */
2213 if (gimple_call_internal_p (stmt
))
2216 /* The heuristic of fold_builtin_alloca_with_align differs before and
2217 after inlining, so we don't require the arg to be changed into a
2218 constant for folding, but just to be constant. */
2219 if (gimple_call_builtin_p (stmt
, BUILT_IN_ALLOCA_WITH_ALIGN
))
2221 tree new_rhs
= fold_builtin_alloca_with_align (stmt
);
2224 bool res
= update_call_from_tree (gsi
, new_rhs
);
2225 tree var
= TREE_OPERAND (TREE_OPERAND (new_rhs
, 0),0);
2227 insert_clobbers_for_var (*gsi
, var
);
2232 /* Propagate into the call arguments. Compared to replace_uses_in
2233 this can use the argument slot types for type verification
2234 instead of the current argument type. We also can safely
2235 drop qualifiers here as we are dealing with constants anyway. */
2236 argt
= TYPE_ARG_TYPES (gimple_call_fntype (stmt
));
2237 for (i
= 0; i
< gimple_call_num_args (stmt
) && argt
;
2238 ++i
, argt
= TREE_CHAIN (argt
))
2240 tree arg
= gimple_call_arg (stmt
, i
);
2241 if (TREE_CODE (arg
) == SSA_NAME
2242 && (val
= get_constant_value (arg
))
2243 && useless_type_conversion_p
2244 (TYPE_MAIN_VARIANT (TREE_VALUE (argt
)),
2245 TYPE_MAIN_VARIANT (TREE_TYPE (val
))))
2247 gimple_call_set_arg (stmt
, i
, unshare_expr (val
));
2257 tree lhs
= gimple_assign_lhs (stmt
);
2260 /* If we have a load that turned out to be constant replace it
2261 as we cannot propagate into all uses in all cases. */
2262 if (gimple_assign_single_p (stmt
)
2263 && TREE_CODE (lhs
) == SSA_NAME
2264 && (val
= get_constant_value (lhs
)))
2266 tree rhs
= unshare_expr (val
);
2267 if (!useless_type_conversion_p (TREE_TYPE (lhs
), TREE_TYPE (rhs
)))
2268 rhs
= fold_build1 (VIEW_CONVERT_EXPR
, TREE_TYPE (lhs
), rhs
);
2269 gimple_assign_set_rhs_from_tree (gsi
, rhs
);
2281 /* Visit the assignment statement STMT. Set the value of its LHS to the
2282 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
2283 creates virtual definitions, set the value of each new name to that
2284 of the RHS (if we can derive a constant out of the RHS).
2285 Value-returning call statements also perform an assignment, and
2286 are handled here. */
2288 static enum ssa_prop_result
2289 visit_assignment (gimple
*stmt
, tree
*output_p
)
2291 ccp_prop_value_t val
;
2292 enum ssa_prop_result retval
= SSA_PROP_NOT_INTERESTING
;
2294 tree lhs
= gimple_get_lhs (stmt
);
2295 if (TREE_CODE (lhs
) == SSA_NAME
)
2297 /* Evaluate the statement, which could be
2298 either a GIMPLE_ASSIGN or a GIMPLE_CALL. */
2299 val
= evaluate_stmt (stmt
);
2301 /* If STMT is an assignment to an SSA_NAME, we only have one
2303 if (set_lattice_value (lhs
, &val
))
2306 if (val
.lattice_val
== VARYING
)
2307 retval
= SSA_PROP_VARYING
;
2309 retval
= SSA_PROP_INTERESTING
;
2317 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
2318 if it can determine which edge will be taken. Otherwise, return
2319 SSA_PROP_VARYING. */
2321 static enum ssa_prop_result
2322 visit_cond_stmt (gimple
*stmt
, edge
*taken_edge_p
)
2324 ccp_prop_value_t val
;
2327 block
= gimple_bb (stmt
);
2328 val
= evaluate_stmt (stmt
);
2329 if (val
.lattice_val
!= CONSTANT
2331 return SSA_PROP_VARYING
;
2333 /* Find which edge out of the conditional block will be taken and add it
2334 to the worklist. If no single edge can be determined statically,
2335 return SSA_PROP_VARYING to feed all the outgoing edges to the
2336 propagation engine. */
2337 *taken_edge_p
= find_taken_edge (block
, val
.value
);
2339 return SSA_PROP_INTERESTING
;
2341 return SSA_PROP_VARYING
;
2345 /* Evaluate statement STMT. If the statement produces an output value and
2346 its evaluation changes the lattice value of its output, return
2347 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
2350 If STMT is a conditional branch and we can determine its truth
2351 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
2352 value, return SSA_PROP_VARYING. */
2354 static enum ssa_prop_result
2355 ccp_visit_stmt (gimple
*stmt
, edge
*taken_edge_p
, tree
*output_p
)
2360 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2362 fprintf (dump_file
, "\nVisiting statement:\n");
2363 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2366 switch (gimple_code (stmt
))
2369 /* If the statement is an assignment that produces a single
2370 output value, evaluate its RHS to see if the lattice value of
2371 its output has changed. */
2372 return visit_assignment (stmt
, output_p
);
2375 /* A value-returning call also performs an assignment. */
2376 if (gimple_call_lhs (stmt
) != NULL_TREE
)
2377 return visit_assignment (stmt
, output_p
);
2382 /* If STMT is a conditional branch, see if we can determine
2383 which branch will be taken. */
2384 /* FIXME. It appears that we should be able to optimize
2385 computed GOTOs here as well. */
2386 return visit_cond_stmt (stmt
, taken_edge_p
);
2392 /* Any other kind of statement is not interesting for constant
2393 propagation and, therefore, not worth simulating. */
2394 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2395 fprintf (dump_file
, "No interesting values produced. Marked VARYING.\n");
2397 /* Definitions made by statements other than assignments to
2398 SSA_NAMEs represent unknown modifications to their outputs.
2399 Mark them VARYING. */
2400 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
2401 set_value_varying (def
);
2403 return SSA_PROP_VARYING
;
2407 /* Main entry point for SSA Conditional Constant Propagation. */
2412 unsigned int todo
= 0;
2413 calculate_dominance_info (CDI_DOMINATORS
);
2415 ssa_propagate (ccp_visit_stmt
, ccp_visit_phi_node
);
2416 if (ccp_finalize ())
2417 todo
= (TODO_cleanup_cfg
| TODO_update_ssa
);
2418 free_dominance_info (CDI_DOMINATORS
);
2425 const pass_data pass_data_ccp
=
2427 GIMPLE_PASS
, /* type */
2429 OPTGROUP_NONE
, /* optinfo_flags */
2430 TV_TREE_CCP
, /* tv_id */
2431 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2432 0, /* properties_provided */
2433 0, /* properties_destroyed */
2434 0, /* todo_flags_start */
2435 TODO_update_address_taken
, /* todo_flags_finish */
2438 class pass_ccp
: public gimple_opt_pass
2441 pass_ccp (gcc::context
*ctxt
)
2442 : gimple_opt_pass (pass_data_ccp
, ctxt
)
2445 /* opt_pass methods: */
2446 opt_pass
* clone () { return new pass_ccp (m_ctxt
); }
2447 virtual bool gate (function
*) { return flag_tree_ccp
!= 0; }
2448 virtual unsigned int execute (function
*) { return do_ssa_ccp (); }
2450 }; // class pass_ccp
2455 make_pass_ccp (gcc::context
*ctxt
)
2457 return new pass_ccp (ctxt
);
2462 /* Try to optimize out __builtin_stack_restore. Optimize it out
2463 if there is another __builtin_stack_restore in the same basic
2464 block and no calls or ASM_EXPRs are in between, or if this block's
2465 only outgoing edge is to EXIT_BLOCK and there are no calls or
2466 ASM_EXPRs after this __builtin_stack_restore. */
2469 optimize_stack_restore (gimple_stmt_iterator i
)
2474 basic_block bb
= gsi_bb (i
);
2475 gimple
*call
= gsi_stmt (i
);
2477 if (gimple_code (call
) != GIMPLE_CALL
2478 || gimple_call_num_args (call
) != 1
2479 || TREE_CODE (gimple_call_arg (call
, 0)) != SSA_NAME
2480 || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call
, 0))))
2483 for (gsi_next (&i
); !gsi_end_p (i
); gsi_next (&i
))
2485 stmt
= gsi_stmt (i
);
2486 if (gimple_code (stmt
) == GIMPLE_ASM
)
2488 if (gimple_code (stmt
) != GIMPLE_CALL
)
2491 callee
= gimple_call_fndecl (stmt
);
2493 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2494 /* All regular builtins are ok, just obviously not alloca. */
2495 || DECL_FUNCTION_CODE (callee
) == BUILT_IN_ALLOCA
2496 || DECL_FUNCTION_CODE (callee
) == BUILT_IN_ALLOCA_WITH_ALIGN
)
2499 if (DECL_FUNCTION_CODE (callee
) == BUILT_IN_STACK_RESTORE
)
2500 goto second_stack_restore
;
2506 /* Allow one successor of the exit block, or zero successors. */
2507 switch (EDGE_COUNT (bb
->succs
))
2512 if (single_succ_edge (bb
)->dest
!= EXIT_BLOCK_PTR_FOR_FN (cfun
))
2518 second_stack_restore
:
2520 /* If there's exactly one use, then zap the call to __builtin_stack_save.
2521 If there are multiple uses, then the last one should remove the call.
2522 In any case, whether the call to __builtin_stack_save can be removed
2523 or not is irrelevant to removing the call to __builtin_stack_restore. */
2524 if (has_single_use (gimple_call_arg (call
, 0)))
2526 gimple
*stack_save
= SSA_NAME_DEF_STMT (gimple_call_arg (call
, 0));
2527 if (is_gimple_call (stack_save
))
2529 callee
= gimple_call_fndecl (stack_save
);
2531 && DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
2532 && DECL_FUNCTION_CODE (callee
) == BUILT_IN_STACK_SAVE
)
2534 gimple_stmt_iterator stack_save_gsi
;
2537 stack_save_gsi
= gsi_for_stmt (stack_save
);
2538 rhs
= build_int_cst (TREE_TYPE (gimple_call_arg (call
, 0)), 0);
2539 update_call_from_tree (&stack_save_gsi
, rhs
);
2544 /* No effect, so the statement will be deleted. */
2545 return integer_zero_node
;
2548 /* If va_list type is a simple pointer and nothing special is needed,
2549 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
2550 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
2551 pointer assignment. */
2554 optimize_stdarg_builtin (gimple
*call
)
2556 tree callee
, lhs
, rhs
, cfun_va_list
;
2557 bool va_list_simple_ptr
;
2558 location_t loc
= gimple_location (call
);
2560 if (gimple_code (call
) != GIMPLE_CALL
)
2563 callee
= gimple_call_fndecl (call
);
2565 cfun_va_list
= targetm
.fn_abi_va_list (callee
);
2566 va_list_simple_ptr
= POINTER_TYPE_P (cfun_va_list
)
2567 && (TREE_TYPE (cfun_va_list
) == void_type_node
2568 || TREE_TYPE (cfun_va_list
) == char_type_node
);
2570 switch (DECL_FUNCTION_CODE (callee
))
2572 case BUILT_IN_VA_START
:
2573 if (!va_list_simple_ptr
2574 || targetm
.expand_builtin_va_start
!= NULL
2575 || !builtin_decl_explicit_p (BUILT_IN_NEXT_ARG
))
2578 if (gimple_call_num_args (call
) != 2)
2581 lhs
= gimple_call_arg (call
, 0);
2582 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2583 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2584 != TYPE_MAIN_VARIANT (cfun_va_list
))
2587 lhs
= build_fold_indirect_ref_loc (loc
, lhs
);
2588 rhs
= build_call_expr_loc (loc
, builtin_decl_explicit (BUILT_IN_NEXT_ARG
),
2589 1, integer_zero_node
);
2590 rhs
= fold_convert_loc (loc
, TREE_TYPE (lhs
), rhs
);
2591 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2593 case BUILT_IN_VA_COPY
:
2594 if (!va_list_simple_ptr
)
2597 if (gimple_call_num_args (call
) != 2)
2600 lhs
= gimple_call_arg (call
, 0);
2601 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2602 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2603 != TYPE_MAIN_VARIANT (cfun_va_list
))
2606 lhs
= build_fold_indirect_ref_loc (loc
, lhs
);
2607 rhs
= gimple_call_arg (call
, 1);
2608 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs
))
2609 != TYPE_MAIN_VARIANT (cfun_va_list
))
2612 rhs
= fold_convert_loc (loc
, TREE_TYPE (lhs
), rhs
);
2613 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2615 case BUILT_IN_VA_END
:
2616 /* No effect, so the statement will be deleted. */
2617 return integer_zero_node
;
2624 /* Attemp to make the block of __builtin_unreachable I unreachable by changing
2625 the incoming jumps. Return true if at least one jump was changed. */
2628 optimize_unreachable (gimple_stmt_iterator i
)
2630 basic_block bb
= gsi_bb (i
);
2631 gimple_stmt_iterator gsi
;
2637 if (flag_sanitize
& SANITIZE_UNREACHABLE
)
2640 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
2642 stmt
= gsi_stmt (gsi
);
2644 if (is_gimple_debug (stmt
))
2647 if (glabel
*label_stmt
= dyn_cast
<glabel
*> (stmt
))
2649 /* Verify we do not need to preserve the label. */
2650 if (FORCED_LABEL (gimple_label_label (label_stmt
)))
2656 /* Only handle the case that __builtin_unreachable is the first statement
2657 in the block. We rely on DCE to remove stmts without side-effects
2658 before __builtin_unreachable. */
2659 if (gsi_stmt (gsi
) != gsi_stmt (i
))
2664 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
2666 gsi
= gsi_last_bb (e
->src
);
2667 if (gsi_end_p (gsi
))
2670 stmt
= gsi_stmt (gsi
);
2671 if (gcond
*cond_stmt
= dyn_cast
<gcond
*> (stmt
))
2673 if (e
->flags
& EDGE_TRUE_VALUE
)
2674 gimple_cond_make_false (cond_stmt
);
2675 else if (e
->flags
& EDGE_FALSE_VALUE
)
2676 gimple_cond_make_true (cond_stmt
);
2679 update_stmt (cond_stmt
);
2683 /* Todo: handle other cases, f.i. switch statement. */
2693 /* A simple pass that attempts to fold all builtin functions. This pass
2694 is run after we've propagated as many constants as we can. */
2698 const pass_data pass_data_fold_builtins
=
2700 GIMPLE_PASS
, /* type */
2702 OPTGROUP_NONE
, /* optinfo_flags */
2703 TV_NONE
, /* tv_id */
2704 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2705 0, /* properties_provided */
2706 0, /* properties_destroyed */
2707 0, /* todo_flags_start */
2708 TODO_update_ssa
, /* todo_flags_finish */
2711 class pass_fold_builtins
: public gimple_opt_pass
2714 pass_fold_builtins (gcc::context
*ctxt
)
2715 : gimple_opt_pass (pass_data_fold_builtins
, ctxt
)
2718 /* opt_pass methods: */
2719 opt_pass
* clone () { return new pass_fold_builtins (m_ctxt
); }
2720 virtual unsigned int execute (function
*);
2722 }; // class pass_fold_builtins
2725 pass_fold_builtins::execute (function
*fun
)
2727 bool cfg_changed
= false;
2729 unsigned int todoflags
= 0;
2731 FOR_EACH_BB_FN (bb
, fun
)
2733 gimple_stmt_iterator i
;
2734 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); )
2736 gimple
*stmt
, *old_stmt
;
2738 enum built_in_function fcode
;
2740 stmt
= gsi_stmt (i
);
2742 if (gimple_code (stmt
) != GIMPLE_CALL
)
2744 /* Remove all *ssaname_N ={v} {CLOBBER}; stmts,
2745 after the last GIMPLE DSE they aren't needed and might
2746 unnecessarily keep the SSA_NAMEs live. */
2747 if (gimple_clobber_p (stmt
))
2749 tree lhs
= gimple_assign_lhs (stmt
);
2750 if (TREE_CODE (lhs
) == MEM_REF
2751 && TREE_CODE (TREE_OPERAND (lhs
, 0)) == SSA_NAME
)
2753 unlink_stmt_vdef (stmt
);
2754 gsi_remove (&i
, true);
2755 release_defs (stmt
);
2763 callee
= gimple_call_fndecl (stmt
);
2764 if (!callee
|| DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
)
2770 fcode
= DECL_FUNCTION_CODE (callee
);
2775 tree result
= NULL_TREE
;
2776 switch (DECL_FUNCTION_CODE (callee
))
2778 case BUILT_IN_CONSTANT_P
:
2779 /* Resolve __builtin_constant_p. If it hasn't been
2780 folded to integer_one_node by now, it's fairly
2781 certain that the value simply isn't constant. */
2782 result
= integer_zero_node
;
2785 case BUILT_IN_ASSUME_ALIGNED
:
2786 /* Remove __builtin_assume_aligned. */
2787 result
= gimple_call_arg (stmt
, 0);
2790 case BUILT_IN_STACK_RESTORE
:
2791 result
= optimize_stack_restore (i
);
2797 case BUILT_IN_UNREACHABLE
:
2798 if (optimize_unreachable (i
))
2802 case BUILT_IN_VA_START
:
2803 case BUILT_IN_VA_END
:
2804 case BUILT_IN_VA_COPY
:
2805 /* These shouldn't be folded before pass_stdarg. */
2806 result
= optimize_stdarg_builtin (stmt
);
2820 if (!update_call_from_tree (&i
, result
))
2821 gimplify_and_update_call_from_tree (&i
, result
);
2824 todoflags
|= TODO_update_address_taken
;
2826 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2828 fprintf (dump_file
, "Simplified\n ");
2829 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2833 stmt
= gsi_stmt (i
);
2836 if (maybe_clean_or_replace_eh_stmt (old_stmt
, stmt
)
2837 && gimple_purge_dead_eh_edges (bb
))
2840 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2842 fprintf (dump_file
, "to\n ");
2843 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2844 fprintf (dump_file
, "\n");
2847 /* Retry the same statement if it changed into another
2848 builtin, there might be new opportunities now. */
2849 if (gimple_code (stmt
) != GIMPLE_CALL
)
2854 callee
= gimple_call_fndecl (stmt
);
2856 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2857 || DECL_FUNCTION_CODE (callee
) == fcode
)
2862 /* Delete unreachable blocks. */
2864 todoflags
|= TODO_cleanup_cfg
;
2872 make_pass_fold_builtins (gcc::context
*ctxt
)
2874 return new pass_fold_builtins (ctxt
);