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"
125 #include "hash-set.h"
126 #include "machmode.h"
128 #include "double-int.h"
132 #include "wide-int.h"
136 #include "fold-const.h"
137 #include "stor-layout.h"
141 #include "hard-reg-set.h"
143 #include "function.h"
144 #include "dominance.h"
146 #include "basic-block.h"
147 #include "gimple-pretty-print.h"
148 #include "hash-table.h"
149 #include "tree-ssa-alias.h"
150 #include "internal-fn.h"
151 #include "gimple-fold.h"
153 #include "gimple-expr.h"
156 #include "gimplify.h"
157 #include "gimple-iterator.h"
158 #include "gimple-ssa.h"
159 #include "tree-cfg.h"
160 #include "tree-phinodes.h"
161 #include "ssa-iterators.h"
162 #include "stringpool.h"
163 #include "tree-ssanames.h"
164 #include "tree-pass.h"
165 #include "tree-ssa-propagate.h"
166 #include "value-prof.h"
167 #include "langhooks.h"
169 #include "diagnostic-core.h"
172 #include "wide-int-print.h"
173 #include "builtins.h"
174 #include "tree-chkp.h"
177 /* Possible lattice values. */
186 struct ccp_prop_value_t
{
188 ccp_lattice_t lattice_val
;
190 /* Propagated value. */
193 /* Mask that applies to the propagated value during CCP. For X
194 with a CONSTANT lattice value X & ~mask == value & ~mask. The
195 zero bits in the mask cover constant values. The ones mean no
200 /* Array of propagated constant values. After propagation,
201 CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If
202 the constant is held in an SSA name representing a memory store
203 (i.e., a VDEF), CONST_VAL[I].MEM_REF will contain the actual
204 memory reference used to store (i.e., the LHS of the assignment
206 static ccp_prop_value_t
*const_val
;
207 static unsigned n_const_val
;
209 static void canonicalize_value (ccp_prop_value_t
*);
210 static bool ccp_fold_stmt (gimple_stmt_iterator
*);
212 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */
215 dump_lattice_value (FILE *outf
, const char *prefix
, ccp_prop_value_t val
)
217 switch (val
.lattice_val
)
220 fprintf (outf
, "%sUNINITIALIZED", prefix
);
223 fprintf (outf
, "%sUNDEFINED", prefix
);
226 fprintf (outf
, "%sVARYING", prefix
);
229 if (TREE_CODE (val
.value
) != INTEGER_CST
232 fprintf (outf
, "%sCONSTANT ", prefix
);
233 print_generic_expr (outf
, val
.value
, dump_flags
);
237 widest_int cval
= wi::bit_and_not (wi::to_widest (val
.value
),
239 fprintf (outf
, "%sCONSTANT ", prefix
);
240 print_hex (cval
, outf
);
241 fprintf (outf
, " (");
242 print_hex (val
.mask
, outf
);
252 /* Print lattice value VAL to stderr. */
254 void debug_lattice_value (ccp_prop_value_t val
);
257 debug_lattice_value (ccp_prop_value_t val
)
259 dump_lattice_value (stderr
, "", val
);
260 fprintf (stderr
, "\n");
263 /* Extend NONZERO_BITS to a full mask, with the upper bits being set. */
266 extend_mask (const wide_int
&nonzero_bits
)
268 return (wi::mask
<widest_int
> (wi::get_precision (nonzero_bits
), true)
269 | widest_int::from (nonzero_bits
, UNSIGNED
));
272 /* Compute a default value for variable VAR and store it in the
273 CONST_VAL array. The following rules are used to get default
276 1- Global and static variables that are declared constant are
279 2- Any other value is considered UNDEFINED. This is useful when
280 considering PHI nodes. PHI arguments that are undefined do not
281 change the constant value of the PHI node, which allows for more
282 constants to be propagated.
284 3- Variables defined by statements other than assignments and PHI
285 nodes are considered VARYING.
287 4- Initial values of variables that are not GIMPLE registers are
288 considered VARYING. */
290 static ccp_prop_value_t
291 get_default_value (tree var
)
293 ccp_prop_value_t val
= { UNINITIALIZED
, NULL_TREE
, 0 };
296 stmt
= SSA_NAME_DEF_STMT (var
);
298 if (gimple_nop_p (stmt
))
300 /* Variables defined by an empty statement are those used
301 before being initialized. If VAR is a local variable, we
302 can assume initially that it is UNDEFINED, otherwise we must
303 consider it VARYING. */
304 if (!virtual_operand_p (var
)
305 && TREE_CODE (SSA_NAME_VAR (var
)) == VAR_DECL
)
306 val
.lattice_val
= UNDEFINED
;
309 val
.lattice_val
= VARYING
;
311 if (flag_tree_bit_ccp
)
313 wide_int nonzero_bits
= get_nonzero_bits (var
);
314 if (nonzero_bits
!= -1)
316 val
.lattice_val
= CONSTANT
;
317 val
.value
= build_zero_cst (TREE_TYPE (var
));
318 val
.mask
= extend_mask (nonzero_bits
);
323 else if (is_gimple_assign (stmt
))
326 if (gimple_assign_single_p (stmt
)
327 && DECL_P (gimple_assign_rhs1 (stmt
))
328 && (cst
= get_symbol_constant_value (gimple_assign_rhs1 (stmt
))))
330 val
.lattice_val
= CONSTANT
;
335 /* Any other variable defined by an assignment is considered
337 val
.lattice_val
= UNDEFINED
;
340 else if ((is_gimple_call (stmt
)
341 && gimple_call_lhs (stmt
) != NULL_TREE
)
342 || gimple_code (stmt
) == GIMPLE_PHI
)
344 /* A variable defined by a call or a PHI node is considered
346 val
.lattice_val
= UNDEFINED
;
350 /* Otherwise, VAR will never take on a constant value. */
351 val
.lattice_val
= VARYING
;
359 /* Get the constant value associated with variable VAR. */
361 static inline ccp_prop_value_t
*
364 ccp_prop_value_t
*val
;
366 if (const_val
== NULL
367 || SSA_NAME_VERSION (var
) >= n_const_val
)
370 val
= &const_val
[SSA_NAME_VERSION (var
)];
371 if (val
->lattice_val
== UNINITIALIZED
)
372 *val
= get_default_value (var
);
374 canonicalize_value (val
);
379 /* Return the constant tree value associated with VAR. */
382 get_constant_value (tree var
)
384 ccp_prop_value_t
*val
;
385 if (TREE_CODE (var
) != SSA_NAME
)
387 if (is_gimple_min_invariant (var
))
391 val
= get_value (var
);
393 && val
->lattice_val
== CONSTANT
394 && (TREE_CODE (val
->value
) != INTEGER_CST
400 /* Sets the value associated with VAR to VARYING. */
403 set_value_varying (tree var
)
405 ccp_prop_value_t
*val
= &const_val
[SSA_NAME_VERSION (var
)];
407 val
->lattice_val
= VARYING
;
408 val
->value
= NULL_TREE
;
412 /* For integer constants, make sure to drop TREE_OVERFLOW. */
415 canonicalize_value (ccp_prop_value_t
*val
)
417 if (val
->lattice_val
!= CONSTANT
)
420 if (TREE_OVERFLOW_P (val
->value
))
421 val
->value
= drop_tree_overflow (val
->value
);
424 /* Return whether the lattice transition is valid. */
427 valid_lattice_transition (ccp_prop_value_t old_val
, ccp_prop_value_t new_val
)
429 /* Lattice transitions must always be monotonically increasing in
431 if (old_val
.lattice_val
< new_val
.lattice_val
)
434 if (old_val
.lattice_val
!= new_val
.lattice_val
)
437 if (!old_val
.value
&& !new_val
.value
)
440 /* Now both lattice values are CONSTANT. */
442 /* Allow transitioning from PHI <&x, not executable> == &x
443 to PHI <&x, &y> == common alignment. */
444 if (TREE_CODE (old_val
.value
) != INTEGER_CST
445 && TREE_CODE (new_val
.value
) == INTEGER_CST
)
448 /* Bit-lattices have to agree in the still valid bits. */
449 if (TREE_CODE (old_val
.value
) == INTEGER_CST
450 && TREE_CODE (new_val
.value
) == INTEGER_CST
)
451 return (wi::bit_and_not (wi::to_widest (old_val
.value
), new_val
.mask
)
452 == wi::bit_and_not (wi::to_widest (new_val
.value
), new_val
.mask
));
454 /* Otherwise constant values have to agree. */
455 if (operand_equal_p (old_val
.value
, new_val
.value
, 0))
458 /* At least the kinds and types should agree now. */
459 if (TREE_CODE (old_val
.value
) != TREE_CODE (new_val
.value
)
460 || !types_compatible_p (TREE_TYPE (old_val
.value
),
461 TREE_TYPE (new_val
.value
)))
464 /* For floats and !HONOR_NANS allow transitions from (partial) NaN
466 tree type
= TREE_TYPE (new_val
.value
);
467 if (SCALAR_FLOAT_TYPE_P (type
)
468 && !HONOR_NANS (type
))
470 if (REAL_VALUE_ISNAN (TREE_REAL_CST (old_val
.value
)))
473 else if (VECTOR_FLOAT_TYPE_P (type
)
474 && !HONOR_NANS (type
))
476 for (unsigned i
= 0; i
< VECTOR_CST_NELTS (old_val
.value
); ++i
)
477 if (!REAL_VALUE_ISNAN
478 (TREE_REAL_CST (VECTOR_CST_ELT (old_val
.value
, i
)))
479 && !operand_equal_p (VECTOR_CST_ELT (old_val
.value
, i
),
480 VECTOR_CST_ELT (new_val
.value
, i
), 0))
484 else if (COMPLEX_FLOAT_TYPE_P (type
)
485 && !HONOR_NANS (type
))
487 if (!REAL_VALUE_ISNAN (TREE_REAL_CST (TREE_REALPART (old_val
.value
)))
488 && !operand_equal_p (TREE_REALPART (old_val
.value
),
489 TREE_REALPART (new_val
.value
), 0))
491 if (!REAL_VALUE_ISNAN (TREE_REAL_CST (TREE_IMAGPART (old_val
.value
)))
492 && !operand_equal_p (TREE_IMAGPART (old_val
.value
),
493 TREE_IMAGPART (new_val
.value
), 0))
500 /* Set the value for variable VAR to NEW_VAL. Return true if the new
501 value is different from VAR's previous value. */
504 set_lattice_value (tree var
, ccp_prop_value_t new_val
)
506 /* We can deal with old UNINITIALIZED values just fine here. */
507 ccp_prop_value_t
*old_val
= &const_val
[SSA_NAME_VERSION (var
)];
509 canonicalize_value (&new_val
);
511 /* We have to be careful to not go up the bitwise lattice
512 represented by the mask.
513 ??? This doesn't seem to be the best place to enforce this. */
514 if (new_val
.lattice_val
== CONSTANT
515 && old_val
->lattice_val
== CONSTANT
516 && TREE_CODE (new_val
.value
) == INTEGER_CST
517 && TREE_CODE (old_val
->value
) == INTEGER_CST
)
519 widest_int diff
= (wi::to_widest (new_val
.value
)
520 ^ wi::to_widest (old_val
->value
));
521 new_val
.mask
= new_val
.mask
| old_val
->mask
| diff
;
524 gcc_checking_assert (valid_lattice_transition (*old_val
, new_val
));
526 /* If *OLD_VAL and NEW_VAL are the same, return false to inform the
527 caller that this was a non-transition. */
528 if (old_val
->lattice_val
!= new_val
.lattice_val
529 || (new_val
.lattice_val
== CONSTANT
530 && TREE_CODE (new_val
.value
) == INTEGER_CST
531 && (TREE_CODE (old_val
->value
) != INTEGER_CST
532 || new_val
.mask
!= old_val
->mask
)))
534 /* ??? We would like to delay creation of INTEGER_CSTs from
535 partially constants here. */
537 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
539 dump_lattice_value (dump_file
, "Lattice value changed to ", new_val
);
540 fprintf (dump_file
, ". Adding SSA edges to worklist.\n");
545 gcc_assert (new_val
.lattice_val
!= UNINITIALIZED
);
552 static ccp_prop_value_t
get_value_for_expr (tree
, bool);
553 static ccp_prop_value_t
bit_value_binop (enum tree_code
, tree
, tree
, tree
);
554 static void bit_value_binop_1 (enum tree_code
, tree
, widest_int
*, widest_int
*,
555 tree
, const widest_int
&, const widest_int
&,
556 tree
, const widest_int
&, const widest_int
&);
558 /* Return a widest_int that can be used for bitwise simplifications
562 value_to_wide_int (ccp_prop_value_t val
)
565 && TREE_CODE (val
.value
) == INTEGER_CST
)
566 return wi::to_widest (val
.value
);
571 /* Return the value for the address expression EXPR based on alignment
574 static ccp_prop_value_t
575 get_value_from_alignment (tree expr
)
577 tree type
= TREE_TYPE (expr
);
578 ccp_prop_value_t val
;
579 unsigned HOST_WIDE_INT bitpos
;
582 gcc_assert (TREE_CODE (expr
) == ADDR_EXPR
);
584 get_pointer_alignment_1 (expr
, &align
, &bitpos
);
585 val
.mask
= (POINTER_TYPE_P (type
) || TYPE_UNSIGNED (type
)
586 ? wi::mask
<widest_int
> (TYPE_PRECISION (type
), false)
587 : -1).and_not (align
/ BITS_PER_UNIT
- 1);
588 val
.lattice_val
= val
.mask
== -1 ? VARYING
: CONSTANT
;
589 if (val
.lattice_val
== CONSTANT
)
590 val
.value
= build_int_cstu (type
, bitpos
/ BITS_PER_UNIT
);
592 val
.value
= NULL_TREE
;
597 /* Return the value for the tree operand EXPR. If FOR_BITS_P is true
598 return constant bits extracted from alignment information for
599 invariant addresses. */
601 static ccp_prop_value_t
602 get_value_for_expr (tree expr
, bool for_bits_p
)
604 ccp_prop_value_t val
;
606 if (TREE_CODE (expr
) == SSA_NAME
)
608 val
= *get_value (expr
);
610 && val
.lattice_val
== CONSTANT
611 && TREE_CODE (val
.value
) == ADDR_EXPR
)
612 val
= get_value_from_alignment (val
.value
);
614 else if (is_gimple_min_invariant (expr
)
615 && (!for_bits_p
|| TREE_CODE (expr
) != ADDR_EXPR
))
617 val
.lattice_val
= CONSTANT
;
620 canonicalize_value (&val
);
622 else if (TREE_CODE (expr
) == ADDR_EXPR
)
623 val
= get_value_from_alignment (expr
);
626 val
.lattice_val
= VARYING
;
628 val
.value
= NULL_TREE
;
633 /* Return the likely CCP lattice value for STMT.
635 If STMT has no operands, then return CONSTANT.
637 Else if undefinedness of operands of STMT cause its value to be
638 undefined, then return UNDEFINED.
640 Else if any operands of STMT are constants, then return CONSTANT.
642 Else return VARYING. */
645 likely_value (gimple stmt
)
647 bool has_constant_operand
, has_undefined_operand
, all_undefined_operands
;
652 enum gimple_code code
= gimple_code (stmt
);
654 /* This function appears to be called only for assignments, calls,
655 conditionals, and switches, due to the logic in visit_stmt. */
656 gcc_assert (code
== GIMPLE_ASSIGN
657 || code
== GIMPLE_CALL
658 || code
== GIMPLE_COND
659 || code
== GIMPLE_SWITCH
);
661 /* If the statement has volatile operands, it won't fold to a
663 if (gimple_has_volatile_ops (stmt
))
666 /* Arrive here for more complex cases. */
667 has_constant_operand
= false;
668 has_undefined_operand
= false;
669 all_undefined_operands
= true;
670 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, iter
, SSA_OP_USE
)
672 ccp_prop_value_t
*val
= get_value (use
);
674 if (val
->lattice_val
== UNDEFINED
)
675 has_undefined_operand
= true;
677 all_undefined_operands
= false;
679 if (val
->lattice_val
== CONSTANT
)
680 has_constant_operand
= true;
683 /* There may be constants in regular rhs operands. For calls we
684 have to ignore lhs, fndecl and static chain, otherwise only
686 for (i
= (is_gimple_call (stmt
) ? 2 : 0) + gimple_has_lhs (stmt
);
687 i
< gimple_num_ops (stmt
); ++i
)
689 tree op
= gimple_op (stmt
, i
);
690 if (!op
|| TREE_CODE (op
) == SSA_NAME
)
692 if (is_gimple_min_invariant (op
))
693 has_constant_operand
= true;
696 if (has_constant_operand
)
697 all_undefined_operands
= false;
699 if (has_undefined_operand
700 && code
== GIMPLE_CALL
701 && gimple_call_internal_p (stmt
))
702 switch (gimple_call_internal_fn (stmt
))
704 /* These 3 builtins use the first argument just as a magic
705 way how to find out a decl uid. */
706 case IFN_GOMP_SIMD_LANE
:
707 case IFN_GOMP_SIMD_VF
:
708 case IFN_GOMP_SIMD_LAST_LANE
:
709 has_undefined_operand
= false;
715 /* If the operation combines operands like COMPLEX_EXPR make sure to
716 not mark the result UNDEFINED if only one part of the result is
718 if (has_undefined_operand
&& all_undefined_operands
)
720 else if (code
== GIMPLE_ASSIGN
&& has_undefined_operand
)
722 switch (gimple_assign_rhs_code (stmt
))
724 /* Unary operators are handled with all_undefined_operands. */
727 case POINTER_PLUS_EXPR
:
728 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected.
729 Not bitwise operators, one VARYING operand may specify the
730 result completely. Not logical operators for the same reason.
731 Not COMPLEX_EXPR as one VARYING operand makes the result partly
732 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because
733 the undefined operand may be promoted. */
737 /* If any part of an address is UNDEFINED, like the index
738 of an ARRAY_EXPR, then treat the result as UNDEFINED. */
745 /* If there was an UNDEFINED operand but the result may be not UNDEFINED
746 fall back to CONSTANT. During iteration UNDEFINED may still drop
748 if (has_undefined_operand
)
751 /* We do not consider virtual operands here -- load from read-only
752 memory may have only VARYING virtual operands, but still be
754 if (has_constant_operand
755 || gimple_references_memory_p (stmt
))
761 /* Returns true if STMT cannot be constant. */
764 surely_varying_stmt_p (gimple stmt
)
766 /* If the statement has operands that we cannot handle, it cannot be
768 if (gimple_has_volatile_ops (stmt
))
771 /* If it is a call and does not return a value or is not a
772 builtin and not an indirect call or a call to function with
773 assume_aligned/alloc_align attribute, it is varying. */
774 if (is_gimple_call (stmt
))
776 tree fndecl
, fntype
= gimple_call_fntype (stmt
);
777 if (!gimple_call_lhs (stmt
)
778 || ((fndecl
= gimple_call_fndecl (stmt
)) != NULL_TREE
779 && !DECL_BUILT_IN (fndecl
)
780 && !lookup_attribute ("assume_aligned",
781 TYPE_ATTRIBUTES (fntype
))
782 && !lookup_attribute ("alloc_align",
783 TYPE_ATTRIBUTES (fntype
))))
787 /* Any other store operation is not interesting. */
788 else if (gimple_vdef (stmt
))
791 /* Anything other than assignments and conditional jumps are not
792 interesting for CCP. */
793 if (gimple_code (stmt
) != GIMPLE_ASSIGN
794 && gimple_code (stmt
) != GIMPLE_COND
795 && gimple_code (stmt
) != GIMPLE_SWITCH
796 && gimple_code (stmt
) != GIMPLE_CALL
)
802 /* Initialize local data structures for CCP. */
805 ccp_initialize (void)
809 n_const_val
= num_ssa_names
;
810 const_val
= XCNEWVEC (ccp_prop_value_t
, n_const_val
);
812 /* Initialize simulation flags for PHI nodes and statements. */
813 FOR_EACH_BB_FN (bb
, cfun
)
815 gimple_stmt_iterator i
;
817 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); gsi_next (&i
))
819 gimple stmt
= gsi_stmt (i
);
822 /* If the statement is a control insn, then we do not
823 want to avoid simulating the statement once. Failure
824 to do so means that those edges will never get added. */
825 if (stmt_ends_bb_p (stmt
))
828 is_varying
= surely_varying_stmt_p (stmt
);
835 /* If the statement will not produce a constant, mark
836 all its outputs VARYING. */
837 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
838 set_value_varying (def
);
840 prop_set_simulate_again (stmt
, !is_varying
);
844 /* Now process PHI nodes. We never clear the simulate_again flag on
845 phi nodes, since we do not know which edges are executable yet,
846 except for phi nodes for virtual operands when we do not do store ccp. */
847 FOR_EACH_BB_FN (bb
, cfun
)
851 for (i
= gsi_start_phis (bb
); !gsi_end_p (i
); gsi_next (&i
))
853 gphi
*phi
= i
.phi ();
855 if (virtual_operand_p (gimple_phi_result (phi
)))
856 prop_set_simulate_again (phi
, false);
858 prop_set_simulate_again (phi
, true);
863 /* Debug count support. Reset the values of ssa names
864 VARYING when the total number ssa names analyzed is
865 beyond the debug count specified. */
871 for (i
= 0; i
< num_ssa_names
; i
++)
875 const_val
[i
].lattice_val
= VARYING
;
876 const_val
[i
].mask
= -1;
877 const_val
[i
].value
= NULL_TREE
;
883 /* Do final substitution of propagated values, cleanup the flowgraph and
884 free allocated storage.
886 Return TRUE when something was optimized. */
891 bool something_changed
;
896 /* Derive alignment and misalignment information from partially
897 constant pointers in the lattice or nonzero bits from partially
898 constant integers. */
899 for (i
= 1; i
< num_ssa_names
; ++i
)
901 tree name
= ssa_name (i
);
902 ccp_prop_value_t
*val
;
903 unsigned int tem
, align
;
906 || (!POINTER_TYPE_P (TREE_TYPE (name
))
907 && (!INTEGRAL_TYPE_P (TREE_TYPE (name
))
908 /* Don't record nonzero bits before IPA to avoid
909 using too much memory. */
910 || first_pass_instance
)))
913 val
= get_value (name
);
914 if (val
->lattice_val
!= CONSTANT
915 || TREE_CODE (val
->value
) != INTEGER_CST
)
918 if (POINTER_TYPE_P (TREE_TYPE (name
)))
920 /* Trailing mask bits specify the alignment, trailing value
921 bits the misalignment. */
922 tem
= val
->mask
.to_uhwi ();
923 align
= (tem
& -tem
);
925 set_ptr_info_alignment (get_ptr_info (name
), align
,
926 (TREE_INT_CST_LOW (val
->value
)
931 unsigned int precision
= TYPE_PRECISION (TREE_TYPE (val
->value
));
932 wide_int nonzero_bits
= wide_int::from (val
->mask
, precision
,
933 UNSIGNED
) | val
->value
;
934 nonzero_bits
&= get_nonzero_bits (name
);
935 set_nonzero_bits (name
, nonzero_bits
);
939 /* Perform substitutions based on the known constant values. */
940 something_changed
= substitute_and_fold (get_constant_value
,
941 ccp_fold_stmt
, true);
945 return something_changed
;;
949 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
952 any M UNDEFINED = any
953 any M VARYING = VARYING
954 Ci M Cj = Ci if (i == j)
955 Ci M Cj = VARYING if (i != j)
959 ccp_lattice_meet (ccp_prop_value_t
*val1
, ccp_prop_value_t
*val2
)
961 if (val1
->lattice_val
== UNDEFINED
)
963 /* UNDEFINED M any = any */
966 else if (val2
->lattice_val
== UNDEFINED
)
968 /* any M UNDEFINED = any
969 Nothing to do. VAL1 already contains the value we want. */
972 else if (val1
->lattice_val
== VARYING
973 || val2
->lattice_val
== VARYING
)
975 /* any M VARYING = VARYING. */
976 val1
->lattice_val
= VARYING
;
978 val1
->value
= NULL_TREE
;
980 else if (val1
->lattice_val
== CONSTANT
981 && val2
->lattice_val
== CONSTANT
982 && TREE_CODE (val1
->value
) == INTEGER_CST
983 && TREE_CODE (val2
->value
) == INTEGER_CST
)
985 /* Ci M Cj = Ci if (i == j)
986 Ci M Cj = VARYING if (i != j)
988 For INTEGER_CSTs mask unequal bits. If no equal bits remain,
990 val1
->mask
= (val1
->mask
| val2
->mask
991 | (wi::to_widest (val1
->value
)
992 ^ wi::to_widest (val2
->value
)));
993 if (val1
->mask
== -1)
995 val1
->lattice_val
= VARYING
;
996 val1
->value
= NULL_TREE
;
999 else if (val1
->lattice_val
== CONSTANT
1000 && val2
->lattice_val
== CONSTANT
1001 && simple_cst_equal (val1
->value
, val2
->value
) == 1)
1003 /* Ci M Cj = Ci if (i == j)
1004 Ci M Cj = VARYING if (i != j)
1006 VAL1 already contains the value we want for equivalent values. */
1008 else if (val1
->lattice_val
== CONSTANT
1009 && val2
->lattice_val
== CONSTANT
1010 && (TREE_CODE (val1
->value
) == ADDR_EXPR
1011 || TREE_CODE (val2
->value
) == ADDR_EXPR
))
1013 /* When not equal addresses are involved try meeting for
1015 ccp_prop_value_t tem
= *val2
;
1016 if (TREE_CODE (val1
->value
) == ADDR_EXPR
)
1017 *val1
= get_value_for_expr (val1
->value
, true);
1018 if (TREE_CODE (val2
->value
) == ADDR_EXPR
)
1019 tem
= get_value_for_expr (val2
->value
, true);
1020 ccp_lattice_meet (val1
, &tem
);
1024 /* Any other combination is VARYING. */
1025 val1
->lattice_val
= VARYING
;
1027 val1
->value
= NULL_TREE
;
1032 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
1033 lattice values to determine PHI_NODE's lattice value. The value of a
1034 PHI node is determined calling ccp_lattice_meet with all the arguments
1035 of the PHI node that are incoming via executable edges. */
1037 static enum ssa_prop_result
1038 ccp_visit_phi_node (gphi
*phi
)
1041 ccp_prop_value_t
*old_val
, new_val
;
1043 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1045 fprintf (dump_file
, "\nVisiting PHI node: ");
1046 print_gimple_stmt (dump_file
, phi
, 0, dump_flags
);
1049 old_val
= get_value (gimple_phi_result (phi
));
1050 switch (old_val
->lattice_val
)
1053 return SSA_PROP_VARYING
;
1060 new_val
.lattice_val
= UNDEFINED
;
1061 new_val
.value
= NULL_TREE
;
1068 for (i
= 0; i
< gimple_phi_num_args (phi
); i
++)
1070 /* Compute the meet operator over all the PHI arguments flowing
1071 through executable edges. */
1072 edge e
= gimple_phi_arg_edge (phi
, i
);
1074 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1077 "\n Argument #%d (%d -> %d %sexecutable)\n",
1078 i
, e
->src
->index
, e
->dest
->index
,
1079 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
1082 /* If the incoming edge is executable, Compute the meet operator for
1083 the existing value of the PHI node and the current PHI argument. */
1084 if (e
->flags
& EDGE_EXECUTABLE
)
1086 tree arg
= gimple_phi_arg (phi
, i
)->def
;
1087 ccp_prop_value_t arg_val
= get_value_for_expr (arg
, false);
1089 ccp_lattice_meet (&new_val
, &arg_val
);
1091 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1093 fprintf (dump_file
, "\t");
1094 print_generic_expr (dump_file
, arg
, dump_flags
);
1095 dump_lattice_value (dump_file
, "\tValue: ", arg_val
);
1096 fprintf (dump_file
, "\n");
1099 if (new_val
.lattice_val
== VARYING
)
1104 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1106 dump_lattice_value (dump_file
, "\n PHI node value: ", new_val
);
1107 fprintf (dump_file
, "\n\n");
1110 /* Make the transition to the new value. */
1111 if (set_lattice_value (gimple_phi_result (phi
), new_val
))
1113 if (new_val
.lattice_val
== VARYING
)
1114 return SSA_PROP_VARYING
;
1116 return SSA_PROP_INTERESTING
;
1119 return SSA_PROP_NOT_INTERESTING
;
1122 /* Return the constant value for OP or OP otherwise. */
1125 valueize_op (tree op
)
1127 if (TREE_CODE (op
) == SSA_NAME
)
1129 tree tem
= get_constant_value (op
);
1136 /* Return the constant value for OP, but signal to not follow SSA
1137 edges if the definition may be simulated again. */
1140 valueize_op_1 (tree op
)
1142 if (TREE_CODE (op
) == SSA_NAME
)
1144 /* If the definition may be simulated again we cannot follow
1145 this SSA edge as the SSA propagator does not necessarily
1146 re-visit the use. */
1147 gimple def_stmt
= SSA_NAME_DEF_STMT (op
);
1148 if (!gimple_nop_p (def_stmt
)
1149 && prop_simulate_again_p (def_stmt
))
1151 tree tem
= get_constant_value (op
);
1158 /* CCP specific front-end to the non-destructive constant folding
1161 Attempt to simplify the RHS of STMT knowing that one or more
1162 operands are constants.
1164 If simplification is possible, return the simplified RHS,
1165 otherwise return the original RHS or NULL_TREE. */
1168 ccp_fold (gimple stmt
)
1170 location_t loc
= gimple_location (stmt
);
1171 switch (gimple_code (stmt
))
1175 /* Handle comparison operators that can appear in GIMPLE form. */
1176 tree op0
= valueize_op (gimple_cond_lhs (stmt
));
1177 tree op1
= valueize_op (gimple_cond_rhs (stmt
));
1178 enum tree_code code
= gimple_cond_code (stmt
);
1179 return fold_binary_loc (loc
, code
, boolean_type_node
, op0
, op1
);
1184 /* Return the constant switch index. */
1185 return valueize_op (gimple_switch_index (as_a
<gswitch
*> (stmt
)));
1190 return gimple_fold_stmt_to_constant_1 (stmt
,
1191 valueize_op
, valueize_op_1
);
1198 /* Apply the operation CODE in type TYPE to the value, mask pair
1199 RVAL and RMASK representing a value of type RTYPE and set
1200 the value, mask pair *VAL and *MASK to the result. */
1203 bit_value_unop_1 (enum tree_code code
, tree type
,
1204 widest_int
*val
, widest_int
*mask
,
1205 tree rtype
, const widest_int
&rval
, const widest_int
&rmask
)
1216 widest_int temv
, temm
;
1217 /* Return ~rval + 1. */
1218 bit_value_unop_1 (BIT_NOT_EXPR
, type
, &temv
, &temm
, type
, rval
, rmask
);
1219 bit_value_binop_1 (PLUS_EXPR
, type
, val
, mask
,
1220 type
, temv
, temm
, type
, 1, 0);
1228 /* First extend mask and value according to the original type. */
1229 sgn
= TYPE_SIGN (rtype
);
1230 *mask
= wi::ext (rmask
, TYPE_PRECISION (rtype
), sgn
);
1231 *val
= wi::ext (rval
, TYPE_PRECISION (rtype
), sgn
);
1233 /* Then extend mask and value according to the target type. */
1234 sgn
= TYPE_SIGN (type
);
1235 *mask
= wi::ext (*mask
, TYPE_PRECISION (type
), sgn
);
1236 *val
= wi::ext (*val
, TYPE_PRECISION (type
), sgn
);
1246 /* Apply the operation CODE in type TYPE to the value, mask pairs
1247 R1VAL, R1MASK and R2VAL, R2MASK representing a values of type R1TYPE
1248 and R2TYPE and set the value, mask pair *VAL and *MASK to the result. */
1251 bit_value_binop_1 (enum tree_code code
, tree type
,
1252 widest_int
*val
, widest_int
*mask
,
1253 tree r1type
, const widest_int
&r1val
,
1254 const widest_int
&r1mask
, tree r2type
,
1255 const widest_int
&r2val
, const widest_int
&r2mask
)
1257 signop sgn
= TYPE_SIGN (type
);
1258 int width
= TYPE_PRECISION (type
);
1259 bool swap_p
= false;
1261 /* Assume we'll get a constant result. Use an initial non varying
1262 value, we fall back to varying in the end if necessary. */
1268 /* The mask is constant where there is a known not
1269 set bit, (m1 | m2) & ((v1 | m1) & (v2 | m2)) */
1270 *mask
= (r1mask
| r2mask
) & (r1val
| r1mask
) & (r2val
| r2mask
);
1271 *val
= r1val
& r2val
;
1275 /* The mask is constant where there is a known
1276 set bit, (m1 | m2) & ~((v1 & ~m1) | (v2 & ~m2)). */
1277 *mask
= (r1mask
| r2mask
)
1278 .and_not (r1val
.and_not (r1mask
) | r2val
.and_not (r2mask
));
1279 *val
= r1val
| r2val
;
1284 *mask
= r1mask
| r2mask
;
1285 *val
= r1val
^ r2val
;
1292 widest_int shift
= r2val
;
1300 if (wi::neg_p (shift
))
1303 if (code
== RROTATE_EXPR
)
1304 code
= LROTATE_EXPR
;
1306 code
= RROTATE_EXPR
;
1308 if (code
== RROTATE_EXPR
)
1310 *mask
= wi::rrotate (r1mask
, shift
, width
);
1311 *val
= wi::rrotate (r1val
, shift
, width
);
1315 *mask
= wi::lrotate (r1mask
, shift
, width
);
1316 *val
= wi::lrotate (r1val
, shift
, width
);
1324 /* ??? We can handle partially known shift counts if we know
1325 its sign. That way we can tell that (x << (y | 8)) & 255
1329 widest_int shift
= r2val
;
1337 if (wi::neg_p (shift
))
1340 if (code
== RSHIFT_EXPR
)
1345 if (code
== RSHIFT_EXPR
)
1347 *mask
= wi::rshift (wi::ext (r1mask
, width
, sgn
), shift
, sgn
);
1348 *val
= wi::rshift (wi::ext (r1val
, width
, sgn
), shift
, sgn
);
1352 *mask
= wi::ext (wi::lshift (r1mask
, shift
), width
, sgn
);
1353 *val
= wi::ext (wi::lshift (r1val
, shift
), width
, sgn
);
1360 case POINTER_PLUS_EXPR
:
1362 /* Do the addition with unknown bits set to zero, to give carry-ins of
1363 zero wherever possible. */
1364 widest_int lo
= r1val
.and_not (r1mask
) + r2val
.and_not (r2mask
);
1365 lo
= wi::ext (lo
, width
, sgn
);
1366 /* Do the addition with unknown bits set to one, to give carry-ins of
1367 one wherever possible. */
1368 widest_int hi
= (r1val
| r1mask
) + (r2val
| r2mask
);
1369 hi
= wi::ext (hi
, width
, sgn
);
1370 /* Each bit in the result is known if (a) the corresponding bits in
1371 both inputs are known, and (b) the carry-in to that bit position
1372 is known. We can check condition (b) by seeing if we got the same
1373 result with minimised carries as with maximised carries. */
1374 *mask
= r1mask
| r2mask
| (lo
^ hi
);
1375 *mask
= wi::ext (*mask
, width
, sgn
);
1376 /* It shouldn't matter whether we choose lo or hi here. */
1383 widest_int temv
, temm
;
1384 bit_value_unop_1 (NEGATE_EXPR
, r2type
, &temv
, &temm
,
1385 r2type
, r2val
, r2mask
);
1386 bit_value_binop_1 (PLUS_EXPR
, type
, val
, mask
,
1387 r1type
, r1val
, r1mask
,
1388 r2type
, temv
, temm
);
1394 /* Just track trailing zeros in both operands and transfer
1395 them to the other. */
1396 int r1tz
= wi::ctz (r1val
| r1mask
);
1397 int r2tz
= wi::ctz (r2val
| r2mask
);
1398 if (r1tz
+ r2tz
>= width
)
1403 else if (r1tz
+ r2tz
> 0)
1405 *mask
= wi::ext (wi::mask
<widest_int
> (r1tz
+ r2tz
, true),
1415 widest_int m
= r1mask
| r2mask
;
1416 if (r1val
.and_not (m
) != r2val
.and_not (m
))
1419 *val
= ((code
== EQ_EXPR
) ? 0 : 1);
1423 /* We know the result of a comparison is always one or zero. */
1433 code
= swap_tree_comparison (code
);
1440 const widest_int
&o1val
= swap_p
? r2val
: r1val
;
1441 const widest_int
&o1mask
= swap_p
? r2mask
: r1mask
;
1442 const widest_int
&o2val
= swap_p
? r1val
: r2val
;
1443 const widest_int
&o2mask
= swap_p
? r1mask
: r2mask
;
1445 /* If the most significant bits are not known we know nothing. */
1446 if (wi::neg_p (o1mask
) || wi::neg_p (o2mask
))
1449 /* For comparisons the signedness is in the comparison operands. */
1450 sgn
= TYPE_SIGN (r1type
);
1452 /* If we know the most significant bits we know the values
1453 value ranges by means of treating varying bits as zero
1454 or one. Do a cross comparison of the max/min pairs. */
1455 maxmin
= wi::cmp (o1val
| o1mask
, o2val
.and_not (o2mask
), sgn
);
1456 minmax
= wi::cmp (o1val
.and_not (o1mask
), o2val
| o2mask
, sgn
);
1457 if (maxmin
< 0) /* o1 is less than o2. */
1462 else if (minmax
> 0) /* o1 is not less or equal to o2. */
1467 else if (maxmin
== minmax
) /* o1 and o2 are equal. */
1469 /* This probably should never happen as we'd have
1470 folded the thing during fully constant value folding. */
1472 *val
= (code
== LE_EXPR
? 1 : 0);
1476 /* We know the result of a comparison is always one or zero. */
1487 /* Return the propagation value when applying the operation CODE to
1488 the value RHS yielding type TYPE. */
1490 static ccp_prop_value_t
1491 bit_value_unop (enum tree_code code
, tree type
, tree rhs
)
1493 ccp_prop_value_t rval
= get_value_for_expr (rhs
, true);
1494 widest_int value
, mask
;
1495 ccp_prop_value_t val
;
1497 if (rval
.lattice_val
== UNDEFINED
)
1500 gcc_assert ((rval
.lattice_val
== CONSTANT
1501 && TREE_CODE (rval
.value
) == INTEGER_CST
)
1502 || rval
.mask
== -1);
1503 bit_value_unop_1 (code
, type
, &value
, &mask
,
1504 TREE_TYPE (rhs
), value_to_wide_int (rval
), rval
.mask
);
1507 val
.lattice_val
= CONSTANT
;
1509 /* ??? Delay building trees here. */
1510 val
.value
= wide_int_to_tree (type
, value
);
1514 val
.lattice_val
= VARYING
;
1515 val
.value
= NULL_TREE
;
1521 /* Return the propagation value when applying the operation CODE to
1522 the values RHS1 and RHS2 yielding type TYPE. */
1524 static ccp_prop_value_t
1525 bit_value_binop (enum tree_code code
, tree type
, tree rhs1
, tree rhs2
)
1527 ccp_prop_value_t r1val
= get_value_for_expr (rhs1
, true);
1528 ccp_prop_value_t r2val
= get_value_for_expr (rhs2
, true);
1529 widest_int value
, mask
;
1530 ccp_prop_value_t val
;
1532 if (r1val
.lattice_val
== UNDEFINED
1533 || r2val
.lattice_val
== UNDEFINED
)
1535 val
.lattice_val
= VARYING
;
1536 val
.value
= NULL_TREE
;
1541 gcc_assert ((r1val
.lattice_val
== CONSTANT
1542 && TREE_CODE (r1val
.value
) == INTEGER_CST
)
1543 || r1val
.mask
== -1);
1544 gcc_assert ((r2val
.lattice_val
== CONSTANT
1545 && TREE_CODE (r2val
.value
) == INTEGER_CST
)
1546 || r2val
.mask
== -1);
1547 bit_value_binop_1 (code
, type
, &value
, &mask
,
1548 TREE_TYPE (rhs1
), value_to_wide_int (r1val
), r1val
.mask
,
1549 TREE_TYPE (rhs2
), value_to_wide_int (r2val
), r2val
.mask
);
1552 val
.lattice_val
= CONSTANT
;
1554 /* ??? Delay building trees here. */
1555 val
.value
= wide_int_to_tree (type
, value
);
1559 val
.lattice_val
= VARYING
;
1560 val
.value
= NULL_TREE
;
1566 /* Return the propagation value for __builtin_assume_aligned
1567 and functions with assume_aligned or alloc_aligned attribute.
1568 For __builtin_assume_aligned, ATTR is NULL_TREE,
1569 for assume_aligned attribute ATTR is non-NULL and ALLOC_ALIGNED
1570 is false, for alloc_aligned attribute ATTR is non-NULL and
1571 ALLOC_ALIGNED is true. */
1573 static ccp_prop_value_t
1574 bit_value_assume_aligned (gimple stmt
, tree attr
, ccp_prop_value_t ptrval
,
1577 tree align
, misalign
= NULL_TREE
, type
;
1578 unsigned HOST_WIDE_INT aligni
, misaligni
= 0;
1579 ccp_prop_value_t alignval
;
1580 widest_int value
, mask
;
1581 ccp_prop_value_t val
;
1583 if (attr
== NULL_TREE
)
1585 tree ptr
= gimple_call_arg (stmt
, 0);
1586 type
= TREE_TYPE (ptr
);
1587 ptrval
= get_value_for_expr (ptr
, true);
1591 tree lhs
= gimple_call_lhs (stmt
);
1592 type
= TREE_TYPE (lhs
);
1595 if (ptrval
.lattice_val
== UNDEFINED
)
1597 gcc_assert ((ptrval
.lattice_val
== CONSTANT
1598 && TREE_CODE (ptrval
.value
) == INTEGER_CST
)
1599 || ptrval
.mask
== -1);
1600 if (attr
== NULL_TREE
)
1602 /* Get aligni and misaligni from __builtin_assume_aligned. */
1603 align
= gimple_call_arg (stmt
, 1);
1604 if (!tree_fits_uhwi_p (align
))
1606 aligni
= tree_to_uhwi (align
);
1607 if (gimple_call_num_args (stmt
) > 2)
1609 misalign
= gimple_call_arg (stmt
, 2);
1610 if (!tree_fits_uhwi_p (misalign
))
1612 misaligni
= tree_to_uhwi (misalign
);
1617 /* Get aligni and misaligni from assume_aligned or
1618 alloc_align attributes. */
1619 if (TREE_VALUE (attr
) == NULL_TREE
)
1621 attr
= TREE_VALUE (attr
);
1622 align
= TREE_VALUE (attr
);
1623 if (!tree_fits_uhwi_p (align
))
1625 aligni
= tree_to_uhwi (align
);
1628 if (aligni
== 0 || aligni
> gimple_call_num_args (stmt
))
1630 align
= gimple_call_arg (stmt
, aligni
- 1);
1631 if (!tree_fits_uhwi_p (align
))
1633 aligni
= tree_to_uhwi (align
);
1635 else if (TREE_CHAIN (attr
) && TREE_VALUE (TREE_CHAIN (attr
)))
1637 misalign
= TREE_VALUE (TREE_CHAIN (attr
));
1638 if (!tree_fits_uhwi_p (misalign
))
1640 misaligni
= tree_to_uhwi (misalign
);
1643 if (aligni
<= 1 || (aligni
& (aligni
- 1)) != 0 || misaligni
>= aligni
)
1646 align
= build_int_cst_type (type
, -aligni
);
1647 alignval
= get_value_for_expr (align
, true);
1648 bit_value_binop_1 (BIT_AND_EXPR
, type
, &value
, &mask
,
1649 type
, value_to_wide_int (ptrval
), ptrval
.mask
,
1650 type
, value_to_wide_int (alignval
), alignval
.mask
);
1653 val
.lattice_val
= CONSTANT
;
1655 gcc_assert ((mask
.to_uhwi () & (aligni
- 1)) == 0);
1656 gcc_assert ((value
.to_uhwi () & (aligni
- 1)) == 0);
1658 /* ??? Delay building trees here. */
1659 val
.value
= wide_int_to_tree (type
, value
);
1663 val
.lattice_val
= VARYING
;
1664 val
.value
= NULL_TREE
;
1670 /* Evaluate statement STMT.
1671 Valid only for assignments, calls, conditionals, and switches. */
1673 static ccp_prop_value_t
1674 evaluate_stmt (gimple stmt
)
1676 ccp_prop_value_t val
;
1677 tree simplified
= NULL_TREE
;
1678 ccp_lattice_t likelyvalue
= likely_value (stmt
);
1679 bool is_constant
= false;
1682 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1684 fprintf (dump_file
, "which is likely ");
1685 switch (likelyvalue
)
1688 fprintf (dump_file
, "CONSTANT");
1691 fprintf (dump_file
, "UNDEFINED");
1694 fprintf (dump_file
, "VARYING");
1698 fprintf (dump_file
, "\n");
1701 /* If the statement is likely to have a CONSTANT result, then try
1702 to fold the statement to determine the constant value. */
1703 /* FIXME. This is the only place that we call ccp_fold.
1704 Since likely_value never returns CONSTANT for calls, we will
1705 not attempt to fold them, including builtins that may profit. */
1706 if (likelyvalue
== CONSTANT
)
1708 fold_defer_overflow_warnings ();
1709 simplified
= ccp_fold (stmt
);
1710 is_constant
= simplified
&& is_gimple_min_invariant (simplified
);
1711 fold_undefer_overflow_warnings (is_constant
, stmt
, 0);
1714 /* The statement produced a constant value. */
1715 val
.lattice_val
= CONSTANT
;
1716 val
.value
= simplified
;
1720 /* If the statement is likely to have a VARYING result, then do not
1721 bother folding the statement. */
1722 else if (likelyvalue
== VARYING
)
1724 enum gimple_code code
= gimple_code (stmt
);
1725 if (code
== GIMPLE_ASSIGN
)
1727 enum tree_code subcode
= gimple_assign_rhs_code (stmt
);
1729 /* Other cases cannot satisfy is_gimple_min_invariant
1731 if (get_gimple_rhs_class (subcode
) == GIMPLE_SINGLE_RHS
)
1732 simplified
= gimple_assign_rhs1 (stmt
);
1734 else if (code
== GIMPLE_SWITCH
)
1735 simplified
= gimple_switch_index (as_a
<gswitch
*> (stmt
));
1737 /* These cannot satisfy is_gimple_min_invariant without folding. */
1738 gcc_assert (code
== GIMPLE_CALL
|| code
== GIMPLE_COND
);
1739 is_constant
= simplified
&& is_gimple_min_invariant (simplified
);
1742 /* The statement produced a constant value. */
1743 val
.lattice_val
= CONSTANT
;
1744 val
.value
= simplified
;
1749 /* Resort to simplification for bitwise tracking. */
1750 if (flag_tree_bit_ccp
1751 && (likelyvalue
== CONSTANT
|| is_gimple_call (stmt
)
1752 || (gimple_assign_single_p (stmt
)
1753 && gimple_assign_rhs_code (stmt
) == ADDR_EXPR
))
1756 enum gimple_code code
= gimple_code (stmt
);
1757 val
.lattice_val
= VARYING
;
1758 val
.value
= NULL_TREE
;
1760 if (code
== GIMPLE_ASSIGN
)
1762 enum tree_code subcode
= gimple_assign_rhs_code (stmt
);
1763 tree rhs1
= gimple_assign_rhs1 (stmt
);
1764 switch (get_gimple_rhs_class (subcode
))
1766 case GIMPLE_SINGLE_RHS
:
1767 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1768 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1769 val
= get_value_for_expr (rhs1
, true);
1772 case GIMPLE_UNARY_RHS
:
1773 if ((INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1774 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1775 && (INTEGRAL_TYPE_P (gimple_expr_type (stmt
))
1776 || POINTER_TYPE_P (gimple_expr_type (stmt
))))
1777 val
= bit_value_unop (subcode
, gimple_expr_type (stmt
), rhs1
);
1780 case GIMPLE_BINARY_RHS
:
1781 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1782 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1784 tree lhs
= gimple_assign_lhs (stmt
);
1785 tree rhs2
= gimple_assign_rhs2 (stmt
);
1786 val
= bit_value_binop (subcode
,
1787 TREE_TYPE (lhs
), rhs1
, rhs2
);
1794 else if (code
== GIMPLE_COND
)
1796 enum tree_code code
= gimple_cond_code (stmt
);
1797 tree rhs1
= gimple_cond_lhs (stmt
);
1798 tree rhs2
= gimple_cond_rhs (stmt
);
1799 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1800 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1801 val
= bit_value_binop (code
, TREE_TYPE (rhs1
), rhs1
, rhs2
);
1803 else if (gimple_call_builtin_p (stmt
, BUILT_IN_NORMAL
))
1805 tree fndecl
= gimple_call_fndecl (stmt
);
1806 switch (DECL_FUNCTION_CODE (fndecl
))
1808 case BUILT_IN_MALLOC
:
1809 case BUILT_IN_REALLOC
:
1810 case BUILT_IN_CALLOC
:
1811 case BUILT_IN_STRDUP
:
1812 case BUILT_IN_STRNDUP
:
1813 val
.lattice_val
= CONSTANT
;
1814 val
.value
= build_int_cst (TREE_TYPE (gimple_get_lhs (stmt
)), 0);
1815 val
.mask
= ~((HOST_WIDE_INT
) MALLOC_ABI_ALIGNMENT
1816 / BITS_PER_UNIT
- 1);
1819 case BUILT_IN_ALLOCA
:
1820 case BUILT_IN_ALLOCA_WITH_ALIGN
:
1821 align
= (DECL_FUNCTION_CODE (fndecl
) == BUILT_IN_ALLOCA_WITH_ALIGN
1822 ? TREE_INT_CST_LOW (gimple_call_arg (stmt
, 1))
1823 : BIGGEST_ALIGNMENT
);
1824 val
.lattice_val
= CONSTANT
;
1825 val
.value
= build_int_cst (TREE_TYPE (gimple_get_lhs (stmt
)), 0);
1826 val
.mask
= ~((HOST_WIDE_INT
) align
/ BITS_PER_UNIT
- 1);
1829 /* These builtins return their first argument, unmodified. */
1830 case BUILT_IN_MEMCPY
:
1831 case BUILT_IN_MEMMOVE
:
1832 case BUILT_IN_MEMSET
:
1833 case BUILT_IN_STRCPY
:
1834 case BUILT_IN_STRNCPY
:
1835 case BUILT_IN_MEMCPY_CHK
:
1836 case BUILT_IN_MEMMOVE_CHK
:
1837 case BUILT_IN_MEMSET_CHK
:
1838 case BUILT_IN_STRCPY_CHK
:
1839 case BUILT_IN_STRNCPY_CHK
:
1840 val
= get_value_for_expr (gimple_call_arg (stmt
, 0), true);
1843 case BUILT_IN_ASSUME_ALIGNED
:
1844 val
= bit_value_assume_aligned (stmt
, NULL_TREE
, val
, false);
1847 case BUILT_IN_ALIGNED_ALLOC
:
1849 tree align
= get_constant_value (gimple_call_arg (stmt
, 0));
1851 && tree_fits_uhwi_p (align
))
1853 unsigned HOST_WIDE_INT aligni
= tree_to_uhwi (align
);
1855 /* align must be power-of-two */
1856 && (aligni
& (aligni
- 1)) == 0)
1858 val
.lattice_val
= CONSTANT
;
1859 val
.value
= build_int_cst (ptr_type_node
, 0);
1869 if (is_gimple_call (stmt
) && gimple_call_lhs (stmt
))
1871 tree fntype
= gimple_call_fntype (stmt
);
1874 tree attrs
= lookup_attribute ("assume_aligned",
1875 TYPE_ATTRIBUTES (fntype
));
1877 val
= bit_value_assume_aligned (stmt
, attrs
, val
, false);
1878 attrs
= lookup_attribute ("alloc_align",
1879 TYPE_ATTRIBUTES (fntype
));
1881 val
= bit_value_assume_aligned (stmt
, attrs
, val
, true);
1884 is_constant
= (val
.lattice_val
== CONSTANT
);
1887 if (flag_tree_bit_ccp
1888 && ((is_constant
&& TREE_CODE (val
.value
) == INTEGER_CST
)
1889 || (!is_constant
&& likelyvalue
!= UNDEFINED
))
1890 && gimple_get_lhs (stmt
)
1891 && TREE_CODE (gimple_get_lhs (stmt
)) == SSA_NAME
)
1893 tree lhs
= gimple_get_lhs (stmt
);
1894 wide_int nonzero_bits
= get_nonzero_bits (lhs
);
1895 if (nonzero_bits
!= -1)
1899 val
.lattice_val
= CONSTANT
;
1900 val
.value
= build_zero_cst (TREE_TYPE (lhs
));
1901 val
.mask
= extend_mask (nonzero_bits
);
1906 if (wi::bit_and_not (val
.value
, nonzero_bits
) != 0)
1907 val
.value
= wide_int_to_tree (TREE_TYPE (lhs
),
1908 nonzero_bits
& val
.value
);
1909 if (nonzero_bits
== 0)
1912 val
.mask
= val
.mask
& extend_mask (nonzero_bits
);
1919 /* The statement produced a nonconstant value. If the statement
1920 had UNDEFINED operands, then the result of the statement
1921 should be UNDEFINED. Otherwise, the statement is VARYING. */
1922 if (likelyvalue
== UNDEFINED
)
1924 val
.lattice_val
= likelyvalue
;
1929 val
.lattice_val
= VARYING
;
1933 val
.value
= NULL_TREE
;
1939 typedef hash_table
<pointer_hash
<gimple_statement_base
> > gimple_htab
;
1941 /* Given a BUILT_IN_STACK_SAVE value SAVED_VAL, insert a clobber of VAR before
1942 each matching BUILT_IN_STACK_RESTORE. Mark visited phis in VISITED. */
1945 insert_clobber_before_stack_restore (tree saved_val
, tree var
,
1946 gimple_htab
**visited
)
1949 gassign
*clobber_stmt
;
1951 imm_use_iterator iter
;
1952 gimple_stmt_iterator i
;
1955 FOR_EACH_IMM_USE_STMT (stmt
, iter
, saved_val
)
1956 if (gimple_call_builtin_p (stmt
, BUILT_IN_STACK_RESTORE
))
1958 clobber
= build_constructor (TREE_TYPE (var
),
1960 TREE_THIS_VOLATILE (clobber
) = 1;
1961 clobber_stmt
= gimple_build_assign (var
, clobber
);
1963 i
= gsi_for_stmt (stmt
);
1964 gsi_insert_before (&i
, clobber_stmt
, GSI_SAME_STMT
);
1966 else if (gimple_code (stmt
) == GIMPLE_PHI
)
1969 *visited
= new gimple_htab (10);
1971 slot
= (*visited
)->find_slot (stmt
, INSERT
);
1976 insert_clobber_before_stack_restore (gimple_phi_result (stmt
), var
,
1979 else if (gimple_assign_ssa_name_copy_p (stmt
))
1980 insert_clobber_before_stack_restore (gimple_assign_lhs (stmt
), var
,
1982 else if (chkp_gimple_call_builtin_p (stmt
, BUILT_IN_CHKP_BNDRET
))
1985 gcc_assert (is_gimple_debug (stmt
));
1988 /* Advance the iterator to the previous non-debug gimple statement in the same
1989 or dominating basic block. */
1992 gsi_prev_dom_bb_nondebug (gimple_stmt_iterator
*i
)
1996 gsi_prev_nondebug (i
);
1997 while (gsi_end_p (*i
))
1999 dom
= get_immediate_dominator (CDI_DOMINATORS
, i
->bb
);
2000 if (dom
== NULL
|| dom
== ENTRY_BLOCK_PTR_FOR_FN (cfun
))
2003 *i
= gsi_last_bb (dom
);
2007 /* Find a BUILT_IN_STACK_SAVE dominating gsi_stmt (I), and insert
2008 a clobber of VAR before each matching BUILT_IN_STACK_RESTORE.
2010 It is possible that BUILT_IN_STACK_SAVE cannot be find in a dominator when a
2011 previous pass (such as DOM) duplicated it along multiple paths to a BB. In
2012 that case the function gives up without inserting the clobbers. */
2015 insert_clobbers_for_var (gimple_stmt_iterator i
, tree var
)
2019 gimple_htab
*visited
= NULL
;
2021 for (; !gsi_end_p (i
); gsi_prev_dom_bb_nondebug (&i
))
2023 stmt
= gsi_stmt (i
);
2025 if (!gimple_call_builtin_p (stmt
, BUILT_IN_STACK_SAVE
))
2028 saved_val
= gimple_call_lhs (stmt
);
2029 if (saved_val
== NULL_TREE
)
2032 insert_clobber_before_stack_restore (saved_val
, var
, &visited
);
2039 /* Detects a __builtin_alloca_with_align with constant size argument. Declares
2040 fixed-size array and returns the address, if found, otherwise returns
2044 fold_builtin_alloca_with_align (gimple stmt
)
2046 unsigned HOST_WIDE_INT size
, threshold
, n_elem
;
2047 tree lhs
, arg
, block
, var
, elem_type
, array_type
;
2050 lhs
= gimple_call_lhs (stmt
);
2051 if (lhs
== NULL_TREE
)
2054 /* Detect constant argument. */
2055 arg
= get_constant_value (gimple_call_arg (stmt
, 0));
2056 if (arg
== NULL_TREE
2057 || TREE_CODE (arg
) != INTEGER_CST
2058 || !tree_fits_uhwi_p (arg
))
2061 size
= tree_to_uhwi (arg
);
2063 /* Heuristic: don't fold large allocas. */
2064 threshold
= (unsigned HOST_WIDE_INT
)PARAM_VALUE (PARAM_LARGE_STACK_FRAME
);
2065 /* In case the alloca is located at function entry, it has the same lifetime
2066 as a declared array, so we allow a larger size. */
2067 block
= gimple_block (stmt
);
2068 if (!(cfun
->after_inlining
2069 && TREE_CODE (BLOCK_SUPERCONTEXT (block
)) == FUNCTION_DECL
))
2071 if (size
> threshold
)
2074 /* Declare array. */
2075 elem_type
= build_nonstandard_integer_type (BITS_PER_UNIT
, 1);
2076 n_elem
= size
* 8 / BITS_PER_UNIT
;
2077 array_type
= build_array_type_nelts (elem_type
, n_elem
);
2078 var
= create_tmp_var (array_type
);
2079 DECL_ALIGN (var
) = TREE_INT_CST_LOW (gimple_call_arg (stmt
, 1));
2081 struct ptr_info_def
*pi
= SSA_NAME_PTR_INFO (lhs
);
2082 if (pi
!= NULL
&& !pi
->pt
.anything
)
2086 singleton_p
= pt_solution_singleton_p (&pi
->pt
, &uid
);
2087 gcc_assert (singleton_p
);
2088 SET_DECL_PT_UID (var
, uid
);
2092 /* Fold alloca to the address of the array. */
2093 return fold_convert (TREE_TYPE (lhs
), build_fold_addr_expr (var
));
2096 /* Fold the stmt at *GSI with CCP specific information that propagating
2097 and regular folding does not catch. */
2100 ccp_fold_stmt (gimple_stmt_iterator
*gsi
)
2102 gimple stmt
= gsi_stmt (*gsi
);
2104 switch (gimple_code (stmt
))
2108 gcond
*cond_stmt
= as_a
<gcond
*> (stmt
);
2109 ccp_prop_value_t val
;
2110 /* Statement evaluation will handle type mismatches in constants
2111 more gracefully than the final propagation. This allows us to
2112 fold more conditionals here. */
2113 val
= evaluate_stmt (stmt
);
2114 if (val
.lattice_val
!= CONSTANT
2120 fprintf (dump_file
, "Folding predicate ");
2121 print_gimple_expr (dump_file
, stmt
, 0, 0);
2122 fprintf (dump_file
, " to ");
2123 print_generic_expr (dump_file
, val
.value
, 0);
2124 fprintf (dump_file
, "\n");
2127 if (integer_zerop (val
.value
))
2128 gimple_cond_make_false (cond_stmt
);
2130 gimple_cond_make_true (cond_stmt
);
2137 tree lhs
= gimple_call_lhs (stmt
);
2138 int flags
= gimple_call_flags (stmt
);
2141 bool changed
= false;
2144 /* If the call was folded into a constant make sure it goes
2145 away even if we cannot propagate into all uses because of
2148 && TREE_CODE (lhs
) == SSA_NAME
2149 && (val
= get_constant_value (lhs
))
2150 /* Don't optimize away calls that have side-effects. */
2151 && (flags
& (ECF_CONST
|ECF_PURE
)) != 0
2152 && (flags
& ECF_LOOPING_CONST_OR_PURE
) == 0)
2154 tree new_rhs
= unshare_expr (val
);
2156 if (!useless_type_conversion_p (TREE_TYPE (lhs
),
2157 TREE_TYPE (new_rhs
)))
2158 new_rhs
= fold_convert (TREE_TYPE (lhs
), new_rhs
);
2159 res
= update_call_from_tree (gsi
, new_rhs
);
2164 /* Internal calls provide no argument types, so the extra laxity
2165 for normal calls does not apply. */
2166 if (gimple_call_internal_p (stmt
))
2169 /* The heuristic of fold_builtin_alloca_with_align differs before and
2170 after inlining, so we don't require the arg to be changed into a
2171 constant for folding, but just to be constant. */
2172 if (gimple_call_builtin_p (stmt
, BUILT_IN_ALLOCA_WITH_ALIGN
))
2174 tree new_rhs
= fold_builtin_alloca_with_align (stmt
);
2177 bool res
= update_call_from_tree (gsi
, new_rhs
);
2178 tree var
= TREE_OPERAND (TREE_OPERAND (new_rhs
, 0),0);
2180 insert_clobbers_for_var (*gsi
, var
);
2185 /* Propagate into the call arguments. Compared to replace_uses_in
2186 this can use the argument slot types for type verification
2187 instead of the current argument type. We also can safely
2188 drop qualifiers here as we are dealing with constants anyway. */
2189 argt
= TYPE_ARG_TYPES (gimple_call_fntype (stmt
));
2190 for (i
= 0; i
< gimple_call_num_args (stmt
) && argt
;
2191 ++i
, argt
= TREE_CHAIN (argt
))
2193 tree arg
= gimple_call_arg (stmt
, i
);
2194 if (TREE_CODE (arg
) == SSA_NAME
2195 && (val
= get_constant_value (arg
))
2196 && useless_type_conversion_p
2197 (TYPE_MAIN_VARIANT (TREE_VALUE (argt
)),
2198 TYPE_MAIN_VARIANT (TREE_TYPE (val
))))
2200 gimple_call_set_arg (stmt
, i
, unshare_expr (val
));
2210 tree lhs
= gimple_assign_lhs (stmt
);
2213 /* If we have a load that turned out to be constant replace it
2214 as we cannot propagate into all uses in all cases. */
2215 if (gimple_assign_single_p (stmt
)
2216 && TREE_CODE (lhs
) == SSA_NAME
2217 && (val
= get_constant_value (lhs
)))
2219 tree rhs
= unshare_expr (val
);
2220 if (!useless_type_conversion_p (TREE_TYPE (lhs
), TREE_TYPE (rhs
)))
2221 rhs
= fold_build1 (VIEW_CONVERT_EXPR
, TREE_TYPE (lhs
), rhs
);
2222 gimple_assign_set_rhs_from_tree (gsi
, rhs
);
2234 /* Visit the assignment statement STMT. Set the value of its LHS to the
2235 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
2236 creates virtual definitions, set the value of each new name to that
2237 of the RHS (if we can derive a constant out of the RHS).
2238 Value-returning call statements also perform an assignment, and
2239 are handled here. */
2241 static enum ssa_prop_result
2242 visit_assignment (gimple stmt
, tree
*output_p
)
2244 ccp_prop_value_t val
;
2245 enum ssa_prop_result retval
;
2247 tree lhs
= gimple_get_lhs (stmt
);
2249 gcc_assert (gimple_code (stmt
) != GIMPLE_CALL
2250 || gimple_call_lhs (stmt
) != NULL_TREE
);
2252 if (gimple_assign_single_p (stmt
)
2253 && gimple_assign_rhs_code (stmt
) == SSA_NAME
)
2254 /* For a simple copy operation, we copy the lattice values. */
2255 val
= *get_value (gimple_assign_rhs1 (stmt
));
2257 /* Evaluate the statement, which could be
2258 either a GIMPLE_ASSIGN or a GIMPLE_CALL. */
2259 val
= evaluate_stmt (stmt
);
2261 retval
= SSA_PROP_NOT_INTERESTING
;
2263 /* Set the lattice value of the statement's output. */
2264 if (TREE_CODE (lhs
) == SSA_NAME
)
2266 /* If STMT is an assignment to an SSA_NAME, we only have one
2268 if (set_lattice_value (lhs
, val
))
2271 if (val
.lattice_val
== VARYING
)
2272 retval
= SSA_PROP_VARYING
;
2274 retval
= SSA_PROP_INTERESTING
;
2282 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
2283 if it can determine which edge will be taken. Otherwise, return
2284 SSA_PROP_VARYING. */
2286 static enum ssa_prop_result
2287 visit_cond_stmt (gimple stmt
, edge
*taken_edge_p
)
2289 ccp_prop_value_t val
;
2292 block
= gimple_bb (stmt
);
2293 val
= evaluate_stmt (stmt
);
2294 if (val
.lattice_val
!= CONSTANT
2296 return SSA_PROP_VARYING
;
2298 /* Find which edge out of the conditional block will be taken and add it
2299 to the worklist. If no single edge can be determined statically,
2300 return SSA_PROP_VARYING to feed all the outgoing edges to the
2301 propagation engine. */
2302 *taken_edge_p
= find_taken_edge (block
, val
.value
);
2304 return SSA_PROP_INTERESTING
;
2306 return SSA_PROP_VARYING
;
2310 /* Evaluate statement STMT. If the statement produces an output value and
2311 its evaluation changes the lattice value of its output, return
2312 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
2315 If STMT is a conditional branch and we can determine its truth
2316 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
2317 value, return SSA_PROP_VARYING. */
2319 static enum ssa_prop_result
2320 ccp_visit_stmt (gimple stmt
, edge
*taken_edge_p
, tree
*output_p
)
2325 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2327 fprintf (dump_file
, "\nVisiting statement:\n");
2328 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2331 switch (gimple_code (stmt
))
2334 /* If the statement is an assignment that produces a single
2335 output value, evaluate its RHS to see if the lattice value of
2336 its output has changed. */
2337 return visit_assignment (stmt
, output_p
);
2340 /* A value-returning call also performs an assignment. */
2341 if (gimple_call_lhs (stmt
) != NULL_TREE
)
2342 return visit_assignment (stmt
, output_p
);
2347 /* If STMT is a conditional branch, see if we can determine
2348 which branch will be taken. */
2349 /* FIXME. It appears that we should be able to optimize
2350 computed GOTOs here as well. */
2351 return visit_cond_stmt (stmt
, taken_edge_p
);
2357 /* Any other kind of statement is not interesting for constant
2358 propagation and, therefore, not worth simulating. */
2359 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2360 fprintf (dump_file
, "No interesting values produced. Marked VARYING.\n");
2362 /* Definitions made by statements other than assignments to
2363 SSA_NAMEs represent unknown modifications to their outputs.
2364 Mark them VARYING. */
2365 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
2367 ccp_prop_value_t v
= { VARYING
, NULL_TREE
, -1 };
2368 set_lattice_value (def
, v
);
2371 return SSA_PROP_VARYING
;
2375 /* Main entry point for SSA Conditional Constant Propagation. */
2380 unsigned int todo
= 0;
2381 calculate_dominance_info (CDI_DOMINATORS
);
2383 ssa_propagate (ccp_visit_stmt
, ccp_visit_phi_node
);
2384 if (ccp_finalize ())
2385 todo
= (TODO_cleanup_cfg
| TODO_update_ssa
);
2386 free_dominance_info (CDI_DOMINATORS
);
2393 const pass_data pass_data_ccp
=
2395 GIMPLE_PASS
, /* type */
2397 OPTGROUP_NONE
, /* optinfo_flags */
2398 TV_TREE_CCP
, /* tv_id */
2399 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2400 0, /* properties_provided */
2401 0, /* properties_destroyed */
2402 0, /* todo_flags_start */
2403 TODO_update_address_taken
, /* todo_flags_finish */
2406 class pass_ccp
: public gimple_opt_pass
2409 pass_ccp (gcc::context
*ctxt
)
2410 : gimple_opt_pass (pass_data_ccp
, ctxt
)
2413 /* opt_pass methods: */
2414 opt_pass
* clone () { return new pass_ccp (m_ctxt
); }
2415 virtual bool gate (function
*) { return flag_tree_ccp
!= 0; }
2416 virtual unsigned int execute (function
*) { return do_ssa_ccp (); }
2418 }; // class pass_ccp
2423 make_pass_ccp (gcc::context
*ctxt
)
2425 return new pass_ccp (ctxt
);
2430 /* Try to optimize out __builtin_stack_restore. Optimize it out
2431 if there is another __builtin_stack_restore in the same basic
2432 block and no calls or ASM_EXPRs are in between, or if this block's
2433 only outgoing edge is to EXIT_BLOCK and there are no calls or
2434 ASM_EXPRs after this __builtin_stack_restore. */
2437 optimize_stack_restore (gimple_stmt_iterator i
)
2442 basic_block bb
= gsi_bb (i
);
2443 gimple call
= gsi_stmt (i
);
2445 if (gimple_code (call
) != GIMPLE_CALL
2446 || gimple_call_num_args (call
) != 1
2447 || TREE_CODE (gimple_call_arg (call
, 0)) != SSA_NAME
2448 || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call
, 0))))
2451 for (gsi_next (&i
); !gsi_end_p (i
); gsi_next (&i
))
2453 stmt
= gsi_stmt (i
);
2454 if (gimple_code (stmt
) == GIMPLE_ASM
)
2456 if (gimple_code (stmt
) != GIMPLE_CALL
)
2459 callee
= gimple_call_fndecl (stmt
);
2461 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2462 /* All regular builtins are ok, just obviously not alloca. */
2463 || DECL_FUNCTION_CODE (callee
) == BUILT_IN_ALLOCA
2464 || DECL_FUNCTION_CODE (callee
) == BUILT_IN_ALLOCA_WITH_ALIGN
)
2467 if (DECL_FUNCTION_CODE (callee
) == BUILT_IN_STACK_RESTORE
)
2468 goto second_stack_restore
;
2474 /* Allow one successor of the exit block, or zero successors. */
2475 switch (EDGE_COUNT (bb
->succs
))
2480 if (single_succ_edge (bb
)->dest
!= EXIT_BLOCK_PTR_FOR_FN (cfun
))
2486 second_stack_restore
:
2488 /* If there's exactly one use, then zap the call to __builtin_stack_save.
2489 If there are multiple uses, then the last one should remove the call.
2490 In any case, whether the call to __builtin_stack_save can be removed
2491 or not is irrelevant to removing the call to __builtin_stack_restore. */
2492 if (has_single_use (gimple_call_arg (call
, 0)))
2494 gimple stack_save
= SSA_NAME_DEF_STMT (gimple_call_arg (call
, 0));
2495 if (is_gimple_call (stack_save
))
2497 callee
= gimple_call_fndecl (stack_save
);
2499 && DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
2500 && DECL_FUNCTION_CODE (callee
) == BUILT_IN_STACK_SAVE
)
2502 gimple_stmt_iterator stack_save_gsi
;
2505 stack_save_gsi
= gsi_for_stmt (stack_save
);
2506 rhs
= build_int_cst (TREE_TYPE (gimple_call_arg (call
, 0)), 0);
2507 update_call_from_tree (&stack_save_gsi
, rhs
);
2512 /* No effect, so the statement will be deleted. */
2513 return integer_zero_node
;
2516 /* If va_list type is a simple pointer and nothing special is needed,
2517 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
2518 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
2519 pointer assignment. */
2522 optimize_stdarg_builtin (gimple call
)
2524 tree callee
, lhs
, rhs
, cfun_va_list
;
2525 bool va_list_simple_ptr
;
2526 location_t loc
= gimple_location (call
);
2528 if (gimple_code (call
) != GIMPLE_CALL
)
2531 callee
= gimple_call_fndecl (call
);
2533 cfun_va_list
= targetm
.fn_abi_va_list (callee
);
2534 va_list_simple_ptr
= POINTER_TYPE_P (cfun_va_list
)
2535 && (TREE_TYPE (cfun_va_list
) == void_type_node
2536 || TREE_TYPE (cfun_va_list
) == char_type_node
);
2538 switch (DECL_FUNCTION_CODE (callee
))
2540 case BUILT_IN_VA_START
:
2541 if (!va_list_simple_ptr
2542 || targetm
.expand_builtin_va_start
!= NULL
2543 || !builtin_decl_explicit_p (BUILT_IN_NEXT_ARG
))
2546 if (gimple_call_num_args (call
) != 2)
2549 lhs
= gimple_call_arg (call
, 0);
2550 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2551 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2552 != TYPE_MAIN_VARIANT (cfun_va_list
))
2555 lhs
= build_fold_indirect_ref_loc (loc
, lhs
);
2556 rhs
= build_call_expr_loc (loc
, builtin_decl_explicit (BUILT_IN_NEXT_ARG
),
2557 1, integer_zero_node
);
2558 rhs
= fold_convert_loc (loc
, TREE_TYPE (lhs
), rhs
);
2559 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2561 case BUILT_IN_VA_COPY
:
2562 if (!va_list_simple_ptr
)
2565 if (gimple_call_num_args (call
) != 2)
2568 lhs
= gimple_call_arg (call
, 0);
2569 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2570 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2571 != TYPE_MAIN_VARIANT (cfun_va_list
))
2574 lhs
= build_fold_indirect_ref_loc (loc
, lhs
);
2575 rhs
= gimple_call_arg (call
, 1);
2576 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs
))
2577 != TYPE_MAIN_VARIANT (cfun_va_list
))
2580 rhs
= fold_convert_loc (loc
, TREE_TYPE (lhs
), rhs
);
2581 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2583 case BUILT_IN_VA_END
:
2584 /* No effect, so the statement will be deleted. */
2585 return integer_zero_node
;
2592 /* Attemp to make the block of __builtin_unreachable I unreachable by changing
2593 the incoming jumps. Return true if at least one jump was changed. */
2596 optimize_unreachable (gimple_stmt_iterator i
)
2598 basic_block bb
= gsi_bb (i
);
2599 gimple_stmt_iterator gsi
;
2605 if (flag_sanitize
& SANITIZE_UNREACHABLE
)
2608 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
2610 stmt
= gsi_stmt (gsi
);
2612 if (is_gimple_debug (stmt
))
2615 if (glabel
*label_stmt
= dyn_cast
<glabel
*> (stmt
))
2617 /* Verify we do not need to preserve the label. */
2618 if (FORCED_LABEL (gimple_label_label (label_stmt
)))
2624 /* Only handle the case that __builtin_unreachable is the first statement
2625 in the block. We rely on DCE to remove stmts without side-effects
2626 before __builtin_unreachable. */
2627 if (gsi_stmt (gsi
) != gsi_stmt (i
))
2632 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
2634 gsi
= gsi_last_bb (e
->src
);
2635 if (gsi_end_p (gsi
))
2638 stmt
= gsi_stmt (gsi
);
2639 if (gcond
*cond_stmt
= dyn_cast
<gcond
*> (stmt
))
2641 if (e
->flags
& EDGE_TRUE_VALUE
)
2642 gimple_cond_make_false (cond_stmt
);
2643 else if (e
->flags
& EDGE_FALSE_VALUE
)
2644 gimple_cond_make_true (cond_stmt
);
2647 update_stmt (cond_stmt
);
2651 /* Todo: handle other cases, f.i. switch statement. */
2661 /* A simple pass that attempts to fold all builtin functions. This pass
2662 is run after we've propagated as many constants as we can. */
2666 const pass_data pass_data_fold_builtins
=
2668 GIMPLE_PASS
, /* type */
2670 OPTGROUP_NONE
, /* optinfo_flags */
2671 TV_NONE
, /* tv_id */
2672 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2673 0, /* properties_provided */
2674 0, /* properties_destroyed */
2675 0, /* todo_flags_start */
2676 TODO_update_ssa
, /* todo_flags_finish */
2679 class pass_fold_builtins
: public gimple_opt_pass
2682 pass_fold_builtins (gcc::context
*ctxt
)
2683 : gimple_opt_pass (pass_data_fold_builtins
, ctxt
)
2686 /* opt_pass methods: */
2687 opt_pass
* clone () { return new pass_fold_builtins (m_ctxt
); }
2688 virtual unsigned int execute (function
*);
2690 }; // class pass_fold_builtins
2693 pass_fold_builtins::execute (function
*fun
)
2695 bool cfg_changed
= false;
2697 unsigned int todoflags
= 0;
2699 FOR_EACH_BB_FN (bb
, fun
)
2701 gimple_stmt_iterator i
;
2702 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); )
2704 gimple stmt
, old_stmt
;
2706 enum built_in_function fcode
;
2708 stmt
= gsi_stmt (i
);
2710 if (gimple_code (stmt
) != GIMPLE_CALL
)
2712 /* Remove all *ssaname_N ={v} {CLOBBER}; stmts,
2713 after the last GIMPLE DSE they aren't needed and might
2714 unnecessarily keep the SSA_NAMEs live. */
2715 if (gimple_clobber_p (stmt
))
2717 tree lhs
= gimple_assign_lhs (stmt
);
2718 if (TREE_CODE (lhs
) == MEM_REF
2719 && TREE_CODE (TREE_OPERAND (lhs
, 0)) == SSA_NAME
)
2721 unlink_stmt_vdef (stmt
);
2722 gsi_remove (&i
, true);
2723 release_defs (stmt
);
2731 callee
= gimple_call_fndecl (stmt
);
2732 if (!callee
|| DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
)
2738 fcode
= DECL_FUNCTION_CODE (callee
);
2743 tree result
= NULL_TREE
;
2744 switch (DECL_FUNCTION_CODE (callee
))
2746 case BUILT_IN_CONSTANT_P
:
2747 /* Resolve __builtin_constant_p. If it hasn't been
2748 folded to integer_one_node by now, it's fairly
2749 certain that the value simply isn't constant. */
2750 result
= integer_zero_node
;
2753 case BUILT_IN_ASSUME_ALIGNED
:
2754 /* Remove __builtin_assume_aligned. */
2755 result
= gimple_call_arg (stmt
, 0);
2758 case BUILT_IN_STACK_RESTORE
:
2759 result
= optimize_stack_restore (i
);
2765 case BUILT_IN_UNREACHABLE
:
2766 if (optimize_unreachable (i
))
2770 case BUILT_IN_VA_START
:
2771 case BUILT_IN_VA_END
:
2772 case BUILT_IN_VA_COPY
:
2773 /* These shouldn't be folded before pass_stdarg. */
2774 result
= optimize_stdarg_builtin (stmt
);
2788 if (!update_call_from_tree (&i
, result
))
2789 gimplify_and_update_call_from_tree (&i
, result
);
2792 todoflags
|= TODO_update_address_taken
;
2794 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2796 fprintf (dump_file
, "Simplified\n ");
2797 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2801 stmt
= gsi_stmt (i
);
2804 if (maybe_clean_or_replace_eh_stmt (old_stmt
, stmt
)
2805 && gimple_purge_dead_eh_edges (bb
))
2808 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2810 fprintf (dump_file
, "to\n ");
2811 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2812 fprintf (dump_file
, "\n");
2815 /* Retry the same statement if it changed into another
2816 builtin, there might be new opportunities now. */
2817 if (gimple_code (stmt
) != GIMPLE_CALL
)
2822 callee
= gimple_call_fndecl (stmt
);
2824 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2825 || DECL_FUNCTION_CODE (callee
) == fcode
)
2830 /* Delete unreachable blocks. */
2832 todoflags
|= TODO_cleanup_cfg
;
2840 make_pass_fold_builtins (gcc::context
*ctxt
)
2842 return new pass_fold_builtins (ctxt
);