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);
589 = wi::sext (val
.mask
, TYPE_PRECISION (type
)) == -1 ? VARYING
: CONSTANT
;
590 if (val
.lattice_val
== CONSTANT
)
591 val
.value
= build_int_cstu (type
, bitpos
/ BITS_PER_UNIT
);
593 val
.value
= NULL_TREE
;
598 /* Return the value for the tree operand EXPR. If FOR_BITS_P is true
599 return constant bits extracted from alignment information for
600 invariant addresses. */
602 static ccp_prop_value_t
603 get_value_for_expr (tree expr
, bool for_bits_p
)
605 ccp_prop_value_t val
;
607 if (TREE_CODE (expr
) == SSA_NAME
)
609 val
= *get_value (expr
);
611 && val
.lattice_val
== CONSTANT
612 && TREE_CODE (val
.value
) == ADDR_EXPR
)
613 val
= get_value_from_alignment (val
.value
);
615 else if (is_gimple_min_invariant (expr
)
616 && (!for_bits_p
|| TREE_CODE (expr
) != ADDR_EXPR
))
618 val
.lattice_val
= CONSTANT
;
621 canonicalize_value (&val
);
623 else if (TREE_CODE (expr
) == ADDR_EXPR
)
624 val
= get_value_from_alignment (expr
);
627 val
.lattice_val
= VARYING
;
629 val
.value
= NULL_TREE
;
634 /* Return the likely CCP lattice value for STMT.
636 If STMT has no operands, then return CONSTANT.
638 Else if undefinedness of operands of STMT cause its value to be
639 undefined, then return UNDEFINED.
641 Else if any operands of STMT are constants, then return CONSTANT.
643 Else return VARYING. */
646 likely_value (gimple stmt
)
648 bool has_constant_operand
, has_undefined_operand
, all_undefined_operands
;
653 enum gimple_code code
= gimple_code (stmt
);
655 /* This function appears to be called only for assignments, calls,
656 conditionals, and switches, due to the logic in visit_stmt. */
657 gcc_assert (code
== GIMPLE_ASSIGN
658 || code
== GIMPLE_CALL
659 || code
== GIMPLE_COND
660 || code
== GIMPLE_SWITCH
);
662 /* If the statement has volatile operands, it won't fold to a
664 if (gimple_has_volatile_ops (stmt
))
667 /* Arrive here for more complex cases. */
668 has_constant_operand
= false;
669 has_undefined_operand
= false;
670 all_undefined_operands
= true;
671 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, iter
, SSA_OP_USE
)
673 ccp_prop_value_t
*val
= get_value (use
);
675 if (val
->lattice_val
== UNDEFINED
)
676 has_undefined_operand
= true;
678 all_undefined_operands
= false;
680 if (val
->lattice_val
== CONSTANT
)
681 has_constant_operand
= true;
684 /* There may be constants in regular rhs operands. For calls we
685 have to ignore lhs, fndecl and static chain, otherwise only
687 for (i
= (is_gimple_call (stmt
) ? 2 : 0) + gimple_has_lhs (stmt
);
688 i
< gimple_num_ops (stmt
); ++i
)
690 tree op
= gimple_op (stmt
, i
);
691 if (!op
|| TREE_CODE (op
) == SSA_NAME
)
693 if (is_gimple_min_invariant (op
))
694 has_constant_operand
= true;
697 if (has_constant_operand
)
698 all_undefined_operands
= false;
700 if (has_undefined_operand
701 && code
== GIMPLE_CALL
702 && gimple_call_internal_p (stmt
))
703 switch (gimple_call_internal_fn (stmt
))
705 /* These 3 builtins use the first argument just as a magic
706 way how to find out a decl uid. */
707 case IFN_GOMP_SIMD_LANE
:
708 case IFN_GOMP_SIMD_VF
:
709 case IFN_GOMP_SIMD_LAST_LANE
:
710 has_undefined_operand
= false;
716 /* If the operation combines operands like COMPLEX_EXPR make sure to
717 not mark the result UNDEFINED if only one part of the result is
719 if (has_undefined_operand
&& all_undefined_operands
)
721 else if (code
== GIMPLE_ASSIGN
&& has_undefined_operand
)
723 switch (gimple_assign_rhs_code (stmt
))
725 /* Unary operators are handled with all_undefined_operands. */
728 case POINTER_PLUS_EXPR
:
729 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected.
730 Not bitwise operators, one VARYING operand may specify the
731 result completely. Not logical operators for the same reason.
732 Not COMPLEX_EXPR as one VARYING operand makes the result partly
733 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because
734 the undefined operand may be promoted. */
738 /* If any part of an address is UNDEFINED, like the index
739 of an ARRAY_EXPR, then treat the result as UNDEFINED. */
746 /* If there was an UNDEFINED operand but the result may be not UNDEFINED
747 fall back to CONSTANT. During iteration UNDEFINED may still drop
749 if (has_undefined_operand
)
752 /* We do not consider virtual operands here -- load from read-only
753 memory may have only VARYING virtual operands, but still be
755 if (has_constant_operand
756 || gimple_references_memory_p (stmt
))
762 /* Returns true if STMT cannot be constant. */
765 surely_varying_stmt_p (gimple stmt
)
767 /* If the statement has operands that we cannot handle, it cannot be
769 if (gimple_has_volatile_ops (stmt
))
772 /* If it is a call and does not return a value or is not a
773 builtin and not an indirect call or a call to function with
774 assume_aligned/alloc_align attribute, it is varying. */
775 if (is_gimple_call (stmt
))
777 tree fndecl
, fntype
= gimple_call_fntype (stmt
);
778 if (!gimple_call_lhs (stmt
)
779 || ((fndecl
= gimple_call_fndecl (stmt
)) != NULL_TREE
780 && !DECL_BUILT_IN (fndecl
)
781 && !lookup_attribute ("assume_aligned",
782 TYPE_ATTRIBUTES (fntype
))
783 && !lookup_attribute ("alloc_align",
784 TYPE_ATTRIBUTES (fntype
))))
788 /* Any other store operation is not interesting. */
789 else if (gimple_vdef (stmt
))
792 /* Anything other than assignments and conditional jumps are not
793 interesting for CCP. */
794 if (gimple_code (stmt
) != GIMPLE_ASSIGN
795 && gimple_code (stmt
) != GIMPLE_COND
796 && gimple_code (stmt
) != GIMPLE_SWITCH
797 && gimple_code (stmt
) != GIMPLE_CALL
)
803 /* Initialize local data structures for CCP. */
806 ccp_initialize (void)
810 n_const_val
= num_ssa_names
;
811 const_val
= XCNEWVEC (ccp_prop_value_t
, n_const_val
);
813 /* Initialize simulation flags for PHI nodes and statements. */
814 FOR_EACH_BB_FN (bb
, cfun
)
816 gimple_stmt_iterator i
;
818 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); gsi_next (&i
))
820 gimple stmt
= gsi_stmt (i
);
823 /* If the statement is a control insn, then we do not
824 want to avoid simulating the statement once. Failure
825 to do so means that those edges will never get added. */
826 if (stmt_ends_bb_p (stmt
))
829 is_varying
= surely_varying_stmt_p (stmt
);
836 /* If the statement will not produce a constant, mark
837 all its outputs VARYING. */
838 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
839 set_value_varying (def
);
841 prop_set_simulate_again (stmt
, !is_varying
);
845 /* Now process PHI nodes. We never clear the simulate_again flag on
846 phi nodes, since we do not know which edges are executable yet,
847 except for phi nodes for virtual operands when we do not do store ccp. */
848 FOR_EACH_BB_FN (bb
, cfun
)
852 for (i
= gsi_start_phis (bb
); !gsi_end_p (i
); gsi_next (&i
))
854 gphi
*phi
= i
.phi ();
856 if (virtual_operand_p (gimple_phi_result (phi
)))
857 prop_set_simulate_again (phi
, false);
859 prop_set_simulate_again (phi
, true);
864 /* Debug count support. Reset the values of ssa names
865 VARYING when the total number ssa names analyzed is
866 beyond the debug count specified. */
872 for (i
= 0; i
< num_ssa_names
; i
++)
876 const_val
[i
].lattice_val
= VARYING
;
877 const_val
[i
].mask
= -1;
878 const_val
[i
].value
= NULL_TREE
;
884 /* Do final substitution of propagated values, cleanup the flowgraph and
885 free allocated storage.
887 Return TRUE when something was optimized. */
892 bool something_changed
;
897 /* Derive alignment and misalignment information from partially
898 constant pointers in the lattice or nonzero bits from partially
899 constant integers. */
900 for (i
= 1; i
< num_ssa_names
; ++i
)
902 tree name
= ssa_name (i
);
903 ccp_prop_value_t
*val
;
904 unsigned int tem
, align
;
907 || (!POINTER_TYPE_P (TREE_TYPE (name
))
908 && (!INTEGRAL_TYPE_P (TREE_TYPE (name
))
909 /* Don't record nonzero bits before IPA to avoid
910 using too much memory. */
911 || first_pass_instance
)))
914 val
= get_value (name
);
915 if (val
->lattice_val
!= CONSTANT
916 || TREE_CODE (val
->value
) != INTEGER_CST
)
919 if (POINTER_TYPE_P (TREE_TYPE (name
)))
921 /* Trailing mask bits specify the alignment, trailing value
922 bits the misalignment. */
923 tem
= val
->mask
.to_uhwi ();
924 align
= (tem
& -tem
);
926 set_ptr_info_alignment (get_ptr_info (name
), align
,
927 (TREE_INT_CST_LOW (val
->value
)
932 unsigned int precision
= TYPE_PRECISION (TREE_TYPE (val
->value
));
933 wide_int nonzero_bits
= wide_int::from (val
->mask
, precision
,
934 UNSIGNED
) | val
->value
;
935 nonzero_bits
&= get_nonzero_bits (name
);
936 set_nonzero_bits (name
, nonzero_bits
);
940 /* Perform substitutions based on the known constant values. */
941 something_changed
= substitute_and_fold (get_constant_value
,
942 ccp_fold_stmt
, true);
946 return something_changed
;;
950 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
953 any M UNDEFINED = any
954 any M VARYING = VARYING
955 Ci M Cj = Ci if (i == j)
956 Ci M Cj = VARYING if (i != j)
960 ccp_lattice_meet (ccp_prop_value_t
*val1
, ccp_prop_value_t
*val2
)
962 if (val1
->lattice_val
== UNDEFINED
)
964 /* UNDEFINED M any = any */
967 else if (val2
->lattice_val
== UNDEFINED
)
969 /* any M UNDEFINED = any
970 Nothing to do. VAL1 already contains the value we want. */
973 else if (val1
->lattice_val
== VARYING
974 || val2
->lattice_val
== VARYING
)
976 /* any M VARYING = VARYING. */
977 val1
->lattice_val
= VARYING
;
979 val1
->value
= NULL_TREE
;
981 else if (val1
->lattice_val
== CONSTANT
982 && val2
->lattice_val
== CONSTANT
983 && TREE_CODE (val1
->value
) == INTEGER_CST
984 && TREE_CODE (val2
->value
) == INTEGER_CST
)
986 /* Ci M Cj = Ci if (i == j)
987 Ci M Cj = VARYING if (i != j)
989 For INTEGER_CSTs mask unequal bits. If no equal bits remain,
991 val1
->mask
= (val1
->mask
| val2
->mask
992 | (wi::to_widest (val1
->value
)
993 ^ wi::to_widest (val2
->value
)));
994 if (wi::sext (val1
->mask
, TYPE_PRECISION (TREE_TYPE (val1
->value
))) == -1)
996 val1
->lattice_val
= VARYING
;
997 val1
->value
= NULL_TREE
;
1000 else if (val1
->lattice_val
== CONSTANT
1001 && val2
->lattice_val
== CONSTANT
1002 && simple_cst_equal (val1
->value
, val2
->value
) == 1)
1004 /* Ci M Cj = Ci if (i == j)
1005 Ci M Cj = VARYING if (i != j)
1007 VAL1 already contains the value we want for equivalent values. */
1009 else if (val1
->lattice_val
== CONSTANT
1010 && val2
->lattice_val
== CONSTANT
1011 && (TREE_CODE (val1
->value
) == ADDR_EXPR
1012 || TREE_CODE (val2
->value
) == ADDR_EXPR
))
1014 /* When not equal addresses are involved try meeting for
1016 ccp_prop_value_t tem
= *val2
;
1017 if (TREE_CODE (val1
->value
) == ADDR_EXPR
)
1018 *val1
= get_value_for_expr (val1
->value
, true);
1019 if (TREE_CODE (val2
->value
) == ADDR_EXPR
)
1020 tem
= get_value_for_expr (val2
->value
, true);
1021 ccp_lattice_meet (val1
, &tem
);
1025 /* Any other combination is VARYING. */
1026 val1
->lattice_val
= VARYING
;
1028 val1
->value
= NULL_TREE
;
1033 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
1034 lattice values to determine PHI_NODE's lattice value. The value of a
1035 PHI node is determined calling ccp_lattice_meet with all the arguments
1036 of the PHI node that are incoming via executable edges. */
1038 static enum ssa_prop_result
1039 ccp_visit_phi_node (gphi
*phi
)
1042 ccp_prop_value_t
*old_val
, new_val
;
1044 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1046 fprintf (dump_file
, "\nVisiting PHI node: ");
1047 print_gimple_stmt (dump_file
, phi
, 0, dump_flags
);
1050 old_val
= get_value (gimple_phi_result (phi
));
1051 switch (old_val
->lattice_val
)
1054 return SSA_PROP_VARYING
;
1061 new_val
.lattice_val
= UNDEFINED
;
1062 new_val
.value
= NULL_TREE
;
1069 for (i
= 0; i
< gimple_phi_num_args (phi
); i
++)
1071 /* Compute the meet operator over all the PHI arguments flowing
1072 through executable edges. */
1073 edge e
= gimple_phi_arg_edge (phi
, i
);
1075 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1078 "\n Argument #%d (%d -> %d %sexecutable)\n",
1079 i
, e
->src
->index
, e
->dest
->index
,
1080 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
1083 /* If the incoming edge is executable, Compute the meet operator for
1084 the existing value of the PHI node and the current PHI argument. */
1085 if (e
->flags
& EDGE_EXECUTABLE
)
1087 tree arg
= gimple_phi_arg (phi
, i
)->def
;
1088 ccp_prop_value_t arg_val
= get_value_for_expr (arg
, false);
1090 ccp_lattice_meet (&new_val
, &arg_val
);
1092 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1094 fprintf (dump_file
, "\t");
1095 print_generic_expr (dump_file
, arg
, dump_flags
);
1096 dump_lattice_value (dump_file
, "\tValue: ", arg_val
);
1097 fprintf (dump_file
, "\n");
1100 if (new_val
.lattice_val
== VARYING
)
1105 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1107 dump_lattice_value (dump_file
, "\n PHI node value: ", new_val
);
1108 fprintf (dump_file
, "\n\n");
1111 /* Make the transition to the new value. */
1112 if (set_lattice_value (gimple_phi_result (phi
), new_val
))
1114 if (new_val
.lattice_val
== VARYING
)
1115 return SSA_PROP_VARYING
;
1117 return SSA_PROP_INTERESTING
;
1120 return SSA_PROP_NOT_INTERESTING
;
1123 /* Return the constant value for OP or OP otherwise. */
1126 valueize_op (tree op
)
1128 if (TREE_CODE (op
) == SSA_NAME
)
1130 tree tem
= get_constant_value (op
);
1137 /* Return the constant value for OP, but signal to not follow SSA
1138 edges if the definition may be simulated again. */
1141 valueize_op_1 (tree op
)
1143 if (TREE_CODE (op
) == SSA_NAME
)
1145 /* If the definition may be simulated again we cannot follow
1146 this SSA edge as the SSA propagator does not necessarily
1147 re-visit the use. */
1148 gimple def_stmt
= SSA_NAME_DEF_STMT (op
);
1149 if (!gimple_nop_p (def_stmt
)
1150 && prop_simulate_again_p (def_stmt
))
1152 tree tem
= get_constant_value (op
);
1159 /* CCP specific front-end to the non-destructive constant folding
1162 Attempt to simplify the RHS of STMT knowing that one or more
1163 operands are constants.
1165 If simplification is possible, return the simplified RHS,
1166 otherwise return the original RHS or NULL_TREE. */
1169 ccp_fold (gimple stmt
)
1171 location_t loc
= gimple_location (stmt
);
1172 switch (gimple_code (stmt
))
1176 /* Handle comparison operators that can appear in GIMPLE form. */
1177 tree op0
= valueize_op (gimple_cond_lhs (stmt
));
1178 tree op1
= valueize_op (gimple_cond_rhs (stmt
));
1179 enum tree_code code
= gimple_cond_code (stmt
);
1180 return fold_binary_loc (loc
, code
, boolean_type_node
, op0
, op1
);
1185 /* Return the constant switch index. */
1186 return valueize_op (gimple_switch_index (as_a
<gswitch
*> (stmt
)));
1191 return gimple_fold_stmt_to_constant_1 (stmt
,
1192 valueize_op
, valueize_op_1
);
1199 /* Apply the operation CODE in type TYPE to the value, mask pair
1200 RVAL and RMASK representing a value of type RTYPE and set
1201 the value, mask pair *VAL and *MASK to the result. */
1204 bit_value_unop_1 (enum tree_code code
, tree type
,
1205 widest_int
*val
, widest_int
*mask
,
1206 tree rtype
, const widest_int
&rval
, const widest_int
&rmask
)
1217 widest_int temv
, temm
;
1218 /* Return ~rval + 1. */
1219 bit_value_unop_1 (BIT_NOT_EXPR
, type
, &temv
, &temm
, type
, rval
, rmask
);
1220 bit_value_binop_1 (PLUS_EXPR
, type
, val
, mask
,
1221 type
, temv
, temm
, type
, 1, 0);
1229 /* First extend mask and value according to the original type. */
1230 sgn
= TYPE_SIGN (rtype
);
1231 *mask
= wi::ext (rmask
, TYPE_PRECISION (rtype
), sgn
);
1232 *val
= wi::ext (rval
, TYPE_PRECISION (rtype
), sgn
);
1234 /* Then extend mask and value according to the target type. */
1235 sgn
= TYPE_SIGN (type
);
1236 *mask
= wi::ext (*mask
, TYPE_PRECISION (type
), sgn
);
1237 *val
= wi::ext (*val
, TYPE_PRECISION (type
), sgn
);
1247 /* Apply the operation CODE in type TYPE to the value, mask pairs
1248 R1VAL, R1MASK and R2VAL, R2MASK representing a values of type R1TYPE
1249 and R2TYPE and set the value, mask pair *VAL and *MASK to the result. */
1252 bit_value_binop_1 (enum tree_code code
, tree type
,
1253 widest_int
*val
, widest_int
*mask
,
1254 tree r1type
, const widest_int
&r1val
,
1255 const widest_int
&r1mask
, tree r2type
,
1256 const widest_int
&r2val
, const widest_int
&r2mask
)
1258 signop sgn
= TYPE_SIGN (type
);
1259 int width
= TYPE_PRECISION (type
);
1260 bool swap_p
= false;
1262 /* Assume we'll get a constant result. Use an initial non varying
1263 value, we fall back to varying in the end if necessary. */
1269 /* The mask is constant where there is a known not
1270 set bit, (m1 | m2) & ((v1 | m1) & (v2 | m2)) */
1271 *mask
= (r1mask
| r2mask
) & (r1val
| r1mask
) & (r2val
| r2mask
);
1272 *val
= r1val
& r2val
;
1276 /* The mask is constant where there is a known
1277 set bit, (m1 | m2) & ~((v1 & ~m1) | (v2 & ~m2)). */
1278 *mask
= (r1mask
| r2mask
)
1279 .and_not (r1val
.and_not (r1mask
) | r2val
.and_not (r2mask
));
1280 *val
= r1val
| r2val
;
1285 *mask
= r1mask
| r2mask
;
1286 *val
= r1val
^ r2val
;
1293 widest_int shift
= r2val
;
1301 if (wi::neg_p (shift
))
1304 if (code
== RROTATE_EXPR
)
1305 code
= LROTATE_EXPR
;
1307 code
= RROTATE_EXPR
;
1309 if (code
== RROTATE_EXPR
)
1311 *mask
= wi::rrotate (r1mask
, shift
, width
);
1312 *val
= wi::rrotate (r1val
, shift
, width
);
1316 *mask
= wi::lrotate (r1mask
, shift
, width
);
1317 *val
= wi::lrotate (r1val
, shift
, width
);
1325 /* ??? We can handle partially known shift counts if we know
1326 its sign. That way we can tell that (x << (y | 8)) & 255
1330 widest_int shift
= r2val
;
1338 if (wi::neg_p (shift
))
1341 if (code
== RSHIFT_EXPR
)
1346 if (code
== RSHIFT_EXPR
)
1348 *mask
= wi::rshift (wi::ext (r1mask
, width
, sgn
), shift
, sgn
);
1349 *val
= wi::rshift (wi::ext (r1val
, width
, sgn
), shift
, sgn
);
1353 *mask
= wi::ext (wi::lshift (r1mask
, shift
), width
, sgn
);
1354 *val
= wi::ext (wi::lshift (r1val
, shift
), width
, sgn
);
1361 case POINTER_PLUS_EXPR
:
1363 /* Do the addition with unknown bits set to zero, to give carry-ins of
1364 zero wherever possible. */
1365 widest_int lo
= r1val
.and_not (r1mask
) + r2val
.and_not (r2mask
);
1366 lo
= wi::ext (lo
, width
, sgn
);
1367 /* Do the addition with unknown bits set to one, to give carry-ins of
1368 one wherever possible. */
1369 widest_int hi
= (r1val
| r1mask
) + (r2val
| r2mask
);
1370 hi
= wi::ext (hi
, width
, sgn
);
1371 /* Each bit in the result is known if (a) the corresponding bits in
1372 both inputs are known, and (b) the carry-in to that bit position
1373 is known. We can check condition (b) by seeing if we got the same
1374 result with minimised carries as with maximised carries. */
1375 *mask
= r1mask
| r2mask
| (lo
^ hi
);
1376 *mask
= wi::ext (*mask
, width
, sgn
);
1377 /* It shouldn't matter whether we choose lo or hi here. */
1384 widest_int temv
, temm
;
1385 bit_value_unop_1 (NEGATE_EXPR
, r2type
, &temv
, &temm
,
1386 r2type
, r2val
, r2mask
);
1387 bit_value_binop_1 (PLUS_EXPR
, type
, val
, mask
,
1388 r1type
, r1val
, r1mask
,
1389 r2type
, temv
, temm
);
1395 /* Just track trailing zeros in both operands and transfer
1396 them to the other. */
1397 int r1tz
= wi::ctz (r1val
| r1mask
);
1398 int r2tz
= wi::ctz (r2val
| r2mask
);
1399 if (r1tz
+ r2tz
>= width
)
1404 else if (r1tz
+ r2tz
> 0)
1406 *mask
= wi::ext (wi::mask
<widest_int
> (r1tz
+ r2tz
, true),
1416 widest_int m
= r1mask
| r2mask
;
1417 if (r1val
.and_not (m
) != r2val
.and_not (m
))
1420 *val
= ((code
== EQ_EXPR
) ? 0 : 1);
1424 /* We know the result of a comparison is always one or zero. */
1434 code
= swap_tree_comparison (code
);
1441 const widest_int
&o1val
= swap_p
? r2val
: r1val
;
1442 const widest_int
&o1mask
= swap_p
? r2mask
: r1mask
;
1443 const widest_int
&o2val
= swap_p
? r1val
: r2val
;
1444 const widest_int
&o2mask
= swap_p
? r1mask
: r2mask
;
1446 /* If the most significant bits are not known we know nothing. */
1447 if (wi::neg_p (o1mask
) || wi::neg_p (o2mask
))
1450 /* For comparisons the signedness is in the comparison operands. */
1451 sgn
= TYPE_SIGN (r1type
);
1453 /* If we know the most significant bits we know the values
1454 value ranges by means of treating varying bits as zero
1455 or one. Do a cross comparison of the max/min pairs. */
1456 maxmin
= wi::cmp (o1val
| o1mask
, o2val
.and_not (o2mask
), sgn
);
1457 minmax
= wi::cmp (o1val
.and_not (o1mask
), o2val
| o2mask
, sgn
);
1458 if (maxmin
< 0) /* o1 is less than o2. */
1463 else if (minmax
> 0) /* o1 is not less or equal to o2. */
1468 else if (maxmin
== minmax
) /* o1 and o2 are equal. */
1470 /* This probably should never happen as we'd have
1471 folded the thing during fully constant value folding. */
1473 *val
= (code
== LE_EXPR
? 1 : 0);
1477 /* We know the result of a comparison is always one or zero. */
1488 /* Return the propagation value when applying the operation CODE to
1489 the value RHS yielding type TYPE. */
1491 static ccp_prop_value_t
1492 bit_value_unop (enum tree_code code
, tree type
, tree rhs
)
1494 ccp_prop_value_t rval
= get_value_for_expr (rhs
, true);
1495 widest_int value
, mask
;
1496 ccp_prop_value_t val
;
1498 if (rval
.lattice_val
== UNDEFINED
)
1501 gcc_assert ((rval
.lattice_val
== CONSTANT
1502 && TREE_CODE (rval
.value
) == INTEGER_CST
)
1503 || wi::sext (rval
.mask
, TYPE_PRECISION (TREE_TYPE (rhs
))) == -1);
1504 bit_value_unop_1 (code
, type
, &value
, &mask
,
1505 TREE_TYPE (rhs
), value_to_wide_int (rval
), rval
.mask
);
1506 if (wi::sext (mask
, TYPE_PRECISION (type
)) != -1)
1508 val
.lattice_val
= CONSTANT
;
1510 /* ??? Delay building trees here. */
1511 val
.value
= wide_int_to_tree (type
, value
);
1515 val
.lattice_val
= VARYING
;
1516 val
.value
= NULL_TREE
;
1522 /* Return the propagation value when applying the operation CODE to
1523 the values RHS1 and RHS2 yielding type TYPE. */
1525 static ccp_prop_value_t
1526 bit_value_binop (enum tree_code code
, tree type
, tree rhs1
, tree rhs2
)
1528 ccp_prop_value_t r1val
= get_value_for_expr (rhs1
, true);
1529 ccp_prop_value_t r2val
= get_value_for_expr (rhs2
, true);
1530 widest_int value
, mask
;
1531 ccp_prop_value_t val
;
1533 if (r1val
.lattice_val
== UNDEFINED
1534 || r2val
.lattice_val
== UNDEFINED
)
1536 val
.lattice_val
= VARYING
;
1537 val
.value
= NULL_TREE
;
1542 gcc_assert ((r1val
.lattice_val
== CONSTANT
1543 && TREE_CODE (r1val
.value
) == INTEGER_CST
)
1544 || wi::sext (r1val
.mask
,
1545 TYPE_PRECISION (TREE_TYPE (rhs1
))) == -1);
1546 gcc_assert ((r2val
.lattice_val
== CONSTANT
1547 && TREE_CODE (r2val
.value
) == INTEGER_CST
)
1548 || wi::sext (r2val
.mask
,
1549 TYPE_PRECISION (TREE_TYPE (rhs2
))) == -1);
1550 bit_value_binop_1 (code
, type
, &value
, &mask
,
1551 TREE_TYPE (rhs1
), value_to_wide_int (r1val
), r1val
.mask
,
1552 TREE_TYPE (rhs2
), value_to_wide_int (r2val
), r2val
.mask
);
1553 if (wi::sext (mask
, TYPE_PRECISION (type
)) != -1)
1555 val
.lattice_val
= CONSTANT
;
1557 /* ??? Delay building trees here. */
1558 val
.value
= wide_int_to_tree (type
, value
);
1562 val
.lattice_val
= VARYING
;
1563 val
.value
= NULL_TREE
;
1569 /* Return the propagation value for __builtin_assume_aligned
1570 and functions with assume_aligned or alloc_aligned attribute.
1571 For __builtin_assume_aligned, ATTR is NULL_TREE,
1572 for assume_aligned attribute ATTR is non-NULL and ALLOC_ALIGNED
1573 is false, for alloc_aligned attribute ATTR is non-NULL and
1574 ALLOC_ALIGNED is true. */
1576 static ccp_prop_value_t
1577 bit_value_assume_aligned (gimple stmt
, tree attr
, ccp_prop_value_t ptrval
,
1580 tree align
, misalign
= NULL_TREE
, type
;
1581 unsigned HOST_WIDE_INT aligni
, misaligni
= 0;
1582 ccp_prop_value_t alignval
;
1583 widest_int value
, mask
;
1584 ccp_prop_value_t val
;
1586 if (attr
== NULL_TREE
)
1588 tree ptr
= gimple_call_arg (stmt
, 0);
1589 type
= TREE_TYPE (ptr
);
1590 ptrval
= get_value_for_expr (ptr
, true);
1594 tree lhs
= gimple_call_lhs (stmt
);
1595 type
= TREE_TYPE (lhs
);
1598 if (ptrval
.lattice_val
== UNDEFINED
)
1600 gcc_assert ((ptrval
.lattice_val
== CONSTANT
1601 && TREE_CODE (ptrval
.value
) == INTEGER_CST
)
1602 || wi::sext (ptrval
.mask
, TYPE_PRECISION (type
)) == -1);
1603 if (attr
== NULL_TREE
)
1605 /* Get aligni and misaligni from __builtin_assume_aligned. */
1606 align
= gimple_call_arg (stmt
, 1);
1607 if (!tree_fits_uhwi_p (align
))
1609 aligni
= tree_to_uhwi (align
);
1610 if (gimple_call_num_args (stmt
) > 2)
1612 misalign
= gimple_call_arg (stmt
, 2);
1613 if (!tree_fits_uhwi_p (misalign
))
1615 misaligni
= tree_to_uhwi (misalign
);
1620 /* Get aligni and misaligni from assume_aligned or
1621 alloc_align attributes. */
1622 if (TREE_VALUE (attr
) == NULL_TREE
)
1624 attr
= TREE_VALUE (attr
);
1625 align
= TREE_VALUE (attr
);
1626 if (!tree_fits_uhwi_p (align
))
1628 aligni
= tree_to_uhwi (align
);
1631 if (aligni
== 0 || aligni
> gimple_call_num_args (stmt
))
1633 align
= gimple_call_arg (stmt
, aligni
- 1);
1634 if (!tree_fits_uhwi_p (align
))
1636 aligni
= tree_to_uhwi (align
);
1638 else if (TREE_CHAIN (attr
) && TREE_VALUE (TREE_CHAIN (attr
)))
1640 misalign
= TREE_VALUE (TREE_CHAIN (attr
));
1641 if (!tree_fits_uhwi_p (misalign
))
1643 misaligni
= tree_to_uhwi (misalign
);
1646 if (aligni
<= 1 || (aligni
& (aligni
- 1)) != 0 || misaligni
>= aligni
)
1649 align
= build_int_cst_type (type
, -aligni
);
1650 alignval
= get_value_for_expr (align
, true);
1651 bit_value_binop_1 (BIT_AND_EXPR
, type
, &value
, &mask
,
1652 type
, value_to_wide_int (ptrval
), ptrval
.mask
,
1653 type
, value_to_wide_int (alignval
), alignval
.mask
);
1654 if (wi::sext (mask
, TYPE_PRECISION (type
)) != -1)
1656 val
.lattice_val
= CONSTANT
;
1658 gcc_assert ((mask
.to_uhwi () & (aligni
- 1)) == 0);
1659 gcc_assert ((value
.to_uhwi () & (aligni
- 1)) == 0);
1661 /* ??? Delay building trees here. */
1662 val
.value
= wide_int_to_tree (type
, value
);
1666 val
.lattice_val
= VARYING
;
1667 val
.value
= NULL_TREE
;
1673 /* Evaluate statement STMT.
1674 Valid only for assignments, calls, conditionals, and switches. */
1676 static ccp_prop_value_t
1677 evaluate_stmt (gimple stmt
)
1679 ccp_prop_value_t val
;
1680 tree simplified
= NULL_TREE
;
1681 ccp_lattice_t likelyvalue
= likely_value (stmt
);
1682 bool is_constant
= false;
1685 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1687 fprintf (dump_file
, "which is likely ");
1688 switch (likelyvalue
)
1691 fprintf (dump_file
, "CONSTANT");
1694 fprintf (dump_file
, "UNDEFINED");
1697 fprintf (dump_file
, "VARYING");
1701 fprintf (dump_file
, "\n");
1704 /* If the statement is likely to have a CONSTANT result, then try
1705 to fold the statement to determine the constant value. */
1706 /* FIXME. This is the only place that we call ccp_fold.
1707 Since likely_value never returns CONSTANT for calls, we will
1708 not attempt to fold them, including builtins that may profit. */
1709 if (likelyvalue
== CONSTANT
)
1711 fold_defer_overflow_warnings ();
1712 simplified
= ccp_fold (stmt
);
1713 is_constant
= simplified
&& is_gimple_min_invariant (simplified
);
1714 fold_undefer_overflow_warnings (is_constant
, stmt
, 0);
1717 /* The statement produced a constant value. */
1718 val
.lattice_val
= CONSTANT
;
1719 val
.value
= simplified
;
1723 /* If the statement is likely to have a VARYING result, then do not
1724 bother folding the statement. */
1725 else if (likelyvalue
== VARYING
)
1727 enum gimple_code code
= gimple_code (stmt
);
1728 if (code
== GIMPLE_ASSIGN
)
1730 enum tree_code subcode
= gimple_assign_rhs_code (stmt
);
1732 /* Other cases cannot satisfy is_gimple_min_invariant
1734 if (get_gimple_rhs_class (subcode
) == GIMPLE_SINGLE_RHS
)
1735 simplified
= gimple_assign_rhs1 (stmt
);
1737 else if (code
== GIMPLE_SWITCH
)
1738 simplified
= gimple_switch_index (as_a
<gswitch
*> (stmt
));
1740 /* These cannot satisfy is_gimple_min_invariant without folding. */
1741 gcc_assert (code
== GIMPLE_CALL
|| code
== GIMPLE_COND
);
1742 is_constant
= simplified
&& is_gimple_min_invariant (simplified
);
1745 /* The statement produced a constant value. */
1746 val
.lattice_val
= CONSTANT
;
1747 val
.value
= simplified
;
1752 /* Resort to simplification for bitwise tracking. */
1753 if (flag_tree_bit_ccp
1754 && (likelyvalue
== CONSTANT
|| is_gimple_call (stmt
)
1755 || (gimple_assign_single_p (stmt
)
1756 && gimple_assign_rhs_code (stmt
) == ADDR_EXPR
))
1759 enum gimple_code code
= gimple_code (stmt
);
1760 val
.lattice_val
= VARYING
;
1761 val
.value
= NULL_TREE
;
1763 if (code
== GIMPLE_ASSIGN
)
1765 enum tree_code subcode
= gimple_assign_rhs_code (stmt
);
1766 tree rhs1
= gimple_assign_rhs1 (stmt
);
1767 switch (get_gimple_rhs_class (subcode
))
1769 case GIMPLE_SINGLE_RHS
:
1770 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1771 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1772 val
= get_value_for_expr (rhs1
, true);
1775 case GIMPLE_UNARY_RHS
:
1776 if ((INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1777 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1778 && (INTEGRAL_TYPE_P (gimple_expr_type (stmt
))
1779 || POINTER_TYPE_P (gimple_expr_type (stmt
))))
1780 val
= bit_value_unop (subcode
, gimple_expr_type (stmt
), rhs1
);
1783 case GIMPLE_BINARY_RHS
:
1784 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1785 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1787 tree lhs
= gimple_assign_lhs (stmt
);
1788 tree rhs2
= gimple_assign_rhs2 (stmt
);
1789 val
= bit_value_binop (subcode
,
1790 TREE_TYPE (lhs
), rhs1
, rhs2
);
1797 else if (code
== GIMPLE_COND
)
1799 enum tree_code code
= gimple_cond_code (stmt
);
1800 tree rhs1
= gimple_cond_lhs (stmt
);
1801 tree rhs2
= gimple_cond_rhs (stmt
);
1802 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1803 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1804 val
= bit_value_binop (code
, TREE_TYPE (rhs1
), rhs1
, rhs2
);
1806 else if (gimple_call_builtin_p (stmt
, BUILT_IN_NORMAL
))
1808 tree fndecl
= gimple_call_fndecl (stmt
);
1809 switch (DECL_FUNCTION_CODE (fndecl
))
1811 case BUILT_IN_MALLOC
:
1812 case BUILT_IN_REALLOC
:
1813 case BUILT_IN_CALLOC
:
1814 case BUILT_IN_STRDUP
:
1815 case BUILT_IN_STRNDUP
:
1816 val
.lattice_val
= CONSTANT
;
1817 val
.value
= build_int_cst (TREE_TYPE (gimple_get_lhs (stmt
)), 0);
1818 val
.mask
= ~((HOST_WIDE_INT
) MALLOC_ABI_ALIGNMENT
1819 / BITS_PER_UNIT
- 1);
1822 case BUILT_IN_ALLOCA
:
1823 case BUILT_IN_ALLOCA_WITH_ALIGN
:
1824 align
= (DECL_FUNCTION_CODE (fndecl
) == BUILT_IN_ALLOCA_WITH_ALIGN
1825 ? TREE_INT_CST_LOW (gimple_call_arg (stmt
, 1))
1826 : BIGGEST_ALIGNMENT
);
1827 val
.lattice_val
= CONSTANT
;
1828 val
.value
= build_int_cst (TREE_TYPE (gimple_get_lhs (stmt
)), 0);
1829 val
.mask
= ~((HOST_WIDE_INT
) align
/ BITS_PER_UNIT
- 1);
1832 /* These builtins return their first argument, unmodified. */
1833 case BUILT_IN_MEMCPY
:
1834 case BUILT_IN_MEMMOVE
:
1835 case BUILT_IN_MEMSET
:
1836 case BUILT_IN_STRCPY
:
1837 case BUILT_IN_STRNCPY
:
1838 case BUILT_IN_MEMCPY_CHK
:
1839 case BUILT_IN_MEMMOVE_CHK
:
1840 case BUILT_IN_MEMSET_CHK
:
1841 case BUILT_IN_STRCPY_CHK
:
1842 case BUILT_IN_STRNCPY_CHK
:
1843 val
= get_value_for_expr (gimple_call_arg (stmt
, 0), true);
1846 case BUILT_IN_ASSUME_ALIGNED
:
1847 val
= bit_value_assume_aligned (stmt
, NULL_TREE
, val
, false);
1850 case BUILT_IN_ALIGNED_ALLOC
:
1852 tree align
= get_constant_value (gimple_call_arg (stmt
, 0));
1854 && tree_fits_uhwi_p (align
))
1856 unsigned HOST_WIDE_INT aligni
= tree_to_uhwi (align
);
1858 /* align must be power-of-two */
1859 && (aligni
& (aligni
- 1)) == 0)
1861 val
.lattice_val
= CONSTANT
;
1862 val
.value
= build_int_cst (ptr_type_node
, 0);
1872 if (is_gimple_call (stmt
) && gimple_call_lhs (stmt
))
1874 tree fntype
= gimple_call_fntype (stmt
);
1877 tree attrs
= lookup_attribute ("assume_aligned",
1878 TYPE_ATTRIBUTES (fntype
));
1880 val
= bit_value_assume_aligned (stmt
, attrs
, val
, false);
1881 attrs
= lookup_attribute ("alloc_align",
1882 TYPE_ATTRIBUTES (fntype
));
1884 val
= bit_value_assume_aligned (stmt
, attrs
, val
, true);
1887 is_constant
= (val
.lattice_val
== CONSTANT
);
1890 if (flag_tree_bit_ccp
1891 && ((is_constant
&& TREE_CODE (val
.value
) == INTEGER_CST
)
1892 || (!is_constant
&& likelyvalue
!= UNDEFINED
))
1893 && gimple_get_lhs (stmt
)
1894 && TREE_CODE (gimple_get_lhs (stmt
)) == SSA_NAME
)
1896 tree lhs
= gimple_get_lhs (stmt
);
1897 wide_int nonzero_bits
= get_nonzero_bits (lhs
);
1898 if (nonzero_bits
!= -1)
1902 val
.lattice_val
= CONSTANT
;
1903 val
.value
= build_zero_cst (TREE_TYPE (lhs
));
1904 val
.mask
= extend_mask (nonzero_bits
);
1909 if (wi::bit_and_not (val
.value
, nonzero_bits
) != 0)
1910 val
.value
= wide_int_to_tree (TREE_TYPE (lhs
),
1911 nonzero_bits
& val
.value
);
1912 if (nonzero_bits
== 0)
1915 val
.mask
= val
.mask
& extend_mask (nonzero_bits
);
1922 /* The statement produced a nonconstant value. If the statement
1923 had UNDEFINED operands, then the result of the statement
1924 should be UNDEFINED. Otherwise, the statement is VARYING. */
1925 if (likelyvalue
== UNDEFINED
)
1927 val
.lattice_val
= likelyvalue
;
1932 val
.lattice_val
= VARYING
;
1936 val
.value
= NULL_TREE
;
1942 typedef hash_table
<pointer_hash
<gimple_statement_base
> > gimple_htab
;
1944 /* Given a BUILT_IN_STACK_SAVE value SAVED_VAL, insert a clobber of VAR before
1945 each matching BUILT_IN_STACK_RESTORE. Mark visited phis in VISITED. */
1948 insert_clobber_before_stack_restore (tree saved_val
, tree var
,
1949 gimple_htab
**visited
)
1952 gassign
*clobber_stmt
;
1954 imm_use_iterator iter
;
1955 gimple_stmt_iterator i
;
1958 FOR_EACH_IMM_USE_STMT (stmt
, iter
, saved_val
)
1959 if (gimple_call_builtin_p (stmt
, BUILT_IN_STACK_RESTORE
))
1961 clobber
= build_constructor (TREE_TYPE (var
),
1963 TREE_THIS_VOLATILE (clobber
) = 1;
1964 clobber_stmt
= gimple_build_assign (var
, clobber
);
1966 i
= gsi_for_stmt (stmt
);
1967 gsi_insert_before (&i
, clobber_stmt
, GSI_SAME_STMT
);
1969 else if (gimple_code (stmt
) == GIMPLE_PHI
)
1972 *visited
= new gimple_htab (10);
1974 slot
= (*visited
)->find_slot (stmt
, INSERT
);
1979 insert_clobber_before_stack_restore (gimple_phi_result (stmt
), var
,
1982 else if (gimple_assign_ssa_name_copy_p (stmt
))
1983 insert_clobber_before_stack_restore (gimple_assign_lhs (stmt
), var
,
1985 else if (chkp_gimple_call_builtin_p (stmt
, BUILT_IN_CHKP_BNDRET
))
1988 gcc_assert (is_gimple_debug (stmt
));
1991 /* Advance the iterator to the previous non-debug gimple statement in the same
1992 or dominating basic block. */
1995 gsi_prev_dom_bb_nondebug (gimple_stmt_iterator
*i
)
1999 gsi_prev_nondebug (i
);
2000 while (gsi_end_p (*i
))
2002 dom
= get_immediate_dominator (CDI_DOMINATORS
, i
->bb
);
2003 if (dom
== NULL
|| dom
== ENTRY_BLOCK_PTR_FOR_FN (cfun
))
2006 *i
= gsi_last_bb (dom
);
2010 /* Find a BUILT_IN_STACK_SAVE dominating gsi_stmt (I), and insert
2011 a clobber of VAR before each matching BUILT_IN_STACK_RESTORE.
2013 It is possible that BUILT_IN_STACK_SAVE cannot be find in a dominator when a
2014 previous pass (such as DOM) duplicated it along multiple paths to a BB. In
2015 that case the function gives up without inserting the clobbers. */
2018 insert_clobbers_for_var (gimple_stmt_iterator i
, tree var
)
2022 gimple_htab
*visited
= NULL
;
2024 for (; !gsi_end_p (i
); gsi_prev_dom_bb_nondebug (&i
))
2026 stmt
= gsi_stmt (i
);
2028 if (!gimple_call_builtin_p (stmt
, BUILT_IN_STACK_SAVE
))
2031 saved_val
= gimple_call_lhs (stmt
);
2032 if (saved_val
== NULL_TREE
)
2035 insert_clobber_before_stack_restore (saved_val
, var
, &visited
);
2042 /* Detects a __builtin_alloca_with_align with constant size argument. Declares
2043 fixed-size array and returns the address, if found, otherwise returns
2047 fold_builtin_alloca_with_align (gimple stmt
)
2049 unsigned HOST_WIDE_INT size
, threshold
, n_elem
;
2050 tree lhs
, arg
, block
, var
, elem_type
, array_type
;
2053 lhs
= gimple_call_lhs (stmt
);
2054 if (lhs
== NULL_TREE
)
2057 /* Detect constant argument. */
2058 arg
= get_constant_value (gimple_call_arg (stmt
, 0));
2059 if (arg
== NULL_TREE
2060 || TREE_CODE (arg
) != INTEGER_CST
2061 || !tree_fits_uhwi_p (arg
))
2064 size
= tree_to_uhwi (arg
);
2066 /* Heuristic: don't fold large allocas. */
2067 threshold
= (unsigned HOST_WIDE_INT
)PARAM_VALUE (PARAM_LARGE_STACK_FRAME
);
2068 /* In case the alloca is located at function entry, it has the same lifetime
2069 as a declared array, so we allow a larger size. */
2070 block
= gimple_block (stmt
);
2071 if (!(cfun
->after_inlining
2072 && TREE_CODE (BLOCK_SUPERCONTEXT (block
)) == FUNCTION_DECL
))
2074 if (size
> threshold
)
2077 /* Declare array. */
2078 elem_type
= build_nonstandard_integer_type (BITS_PER_UNIT
, 1);
2079 n_elem
= size
* 8 / BITS_PER_UNIT
;
2080 array_type
= build_array_type_nelts (elem_type
, n_elem
);
2081 var
= create_tmp_var (array_type
);
2082 DECL_ALIGN (var
) = TREE_INT_CST_LOW (gimple_call_arg (stmt
, 1));
2084 struct ptr_info_def
*pi
= SSA_NAME_PTR_INFO (lhs
);
2085 if (pi
!= NULL
&& !pi
->pt
.anything
)
2089 singleton_p
= pt_solution_singleton_p (&pi
->pt
, &uid
);
2090 gcc_assert (singleton_p
);
2091 SET_DECL_PT_UID (var
, uid
);
2095 /* Fold alloca to the address of the array. */
2096 return fold_convert (TREE_TYPE (lhs
), build_fold_addr_expr (var
));
2099 /* Fold the stmt at *GSI with CCP specific information that propagating
2100 and regular folding does not catch. */
2103 ccp_fold_stmt (gimple_stmt_iterator
*gsi
)
2105 gimple stmt
= gsi_stmt (*gsi
);
2107 switch (gimple_code (stmt
))
2111 gcond
*cond_stmt
= as_a
<gcond
*> (stmt
);
2112 ccp_prop_value_t val
;
2113 /* Statement evaluation will handle type mismatches in constants
2114 more gracefully than the final propagation. This allows us to
2115 fold more conditionals here. */
2116 val
= evaluate_stmt (stmt
);
2117 if (val
.lattice_val
!= CONSTANT
2123 fprintf (dump_file
, "Folding predicate ");
2124 print_gimple_expr (dump_file
, stmt
, 0, 0);
2125 fprintf (dump_file
, " to ");
2126 print_generic_expr (dump_file
, val
.value
, 0);
2127 fprintf (dump_file
, "\n");
2130 if (integer_zerop (val
.value
))
2131 gimple_cond_make_false (cond_stmt
);
2133 gimple_cond_make_true (cond_stmt
);
2140 tree lhs
= gimple_call_lhs (stmt
);
2141 int flags
= gimple_call_flags (stmt
);
2144 bool changed
= false;
2147 /* If the call was folded into a constant make sure it goes
2148 away even if we cannot propagate into all uses because of
2151 && TREE_CODE (lhs
) == SSA_NAME
2152 && (val
= get_constant_value (lhs
))
2153 /* Don't optimize away calls that have side-effects. */
2154 && (flags
& (ECF_CONST
|ECF_PURE
)) != 0
2155 && (flags
& ECF_LOOPING_CONST_OR_PURE
) == 0)
2157 tree new_rhs
= unshare_expr (val
);
2159 if (!useless_type_conversion_p (TREE_TYPE (lhs
),
2160 TREE_TYPE (new_rhs
)))
2161 new_rhs
= fold_convert (TREE_TYPE (lhs
), new_rhs
);
2162 res
= update_call_from_tree (gsi
, new_rhs
);
2167 /* Internal calls provide no argument types, so the extra laxity
2168 for normal calls does not apply. */
2169 if (gimple_call_internal_p (stmt
))
2172 /* The heuristic of fold_builtin_alloca_with_align differs before and
2173 after inlining, so we don't require the arg to be changed into a
2174 constant for folding, but just to be constant. */
2175 if (gimple_call_builtin_p (stmt
, BUILT_IN_ALLOCA_WITH_ALIGN
))
2177 tree new_rhs
= fold_builtin_alloca_with_align (stmt
);
2180 bool res
= update_call_from_tree (gsi
, new_rhs
);
2181 tree var
= TREE_OPERAND (TREE_OPERAND (new_rhs
, 0),0);
2183 insert_clobbers_for_var (*gsi
, var
);
2188 /* Propagate into the call arguments. Compared to replace_uses_in
2189 this can use the argument slot types for type verification
2190 instead of the current argument type. We also can safely
2191 drop qualifiers here as we are dealing with constants anyway. */
2192 argt
= TYPE_ARG_TYPES (gimple_call_fntype (stmt
));
2193 for (i
= 0; i
< gimple_call_num_args (stmt
) && argt
;
2194 ++i
, argt
= TREE_CHAIN (argt
))
2196 tree arg
= gimple_call_arg (stmt
, i
);
2197 if (TREE_CODE (arg
) == SSA_NAME
2198 && (val
= get_constant_value (arg
))
2199 && useless_type_conversion_p
2200 (TYPE_MAIN_VARIANT (TREE_VALUE (argt
)),
2201 TYPE_MAIN_VARIANT (TREE_TYPE (val
))))
2203 gimple_call_set_arg (stmt
, i
, unshare_expr (val
));
2213 tree lhs
= gimple_assign_lhs (stmt
);
2216 /* If we have a load that turned out to be constant replace it
2217 as we cannot propagate into all uses in all cases. */
2218 if (gimple_assign_single_p (stmt
)
2219 && TREE_CODE (lhs
) == SSA_NAME
2220 && (val
= get_constant_value (lhs
)))
2222 tree rhs
= unshare_expr (val
);
2223 if (!useless_type_conversion_p (TREE_TYPE (lhs
), TREE_TYPE (rhs
)))
2224 rhs
= fold_build1 (VIEW_CONVERT_EXPR
, TREE_TYPE (lhs
), rhs
);
2225 gimple_assign_set_rhs_from_tree (gsi
, rhs
);
2237 /* Visit the assignment statement STMT. Set the value of its LHS to the
2238 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
2239 creates virtual definitions, set the value of each new name to that
2240 of the RHS (if we can derive a constant out of the RHS).
2241 Value-returning call statements also perform an assignment, and
2242 are handled here. */
2244 static enum ssa_prop_result
2245 visit_assignment (gimple stmt
, tree
*output_p
)
2247 ccp_prop_value_t val
;
2248 enum ssa_prop_result retval
;
2250 tree lhs
= gimple_get_lhs (stmt
);
2252 gcc_assert (gimple_code (stmt
) != GIMPLE_CALL
2253 || gimple_call_lhs (stmt
) != NULL_TREE
);
2255 if (gimple_assign_single_p (stmt
)
2256 && gimple_assign_rhs_code (stmt
) == SSA_NAME
)
2257 /* For a simple copy operation, we copy the lattice values. */
2258 val
= *get_value (gimple_assign_rhs1 (stmt
));
2260 /* Evaluate the statement, which could be
2261 either a GIMPLE_ASSIGN or a GIMPLE_CALL. */
2262 val
= evaluate_stmt (stmt
);
2264 retval
= SSA_PROP_NOT_INTERESTING
;
2266 /* Set the lattice value of the statement's output. */
2267 if (TREE_CODE (lhs
) == SSA_NAME
)
2269 /* If STMT is an assignment to an SSA_NAME, we only have one
2271 if (set_lattice_value (lhs
, val
))
2274 if (val
.lattice_val
== VARYING
)
2275 retval
= SSA_PROP_VARYING
;
2277 retval
= SSA_PROP_INTERESTING
;
2285 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
2286 if it can determine which edge will be taken. Otherwise, return
2287 SSA_PROP_VARYING. */
2289 static enum ssa_prop_result
2290 visit_cond_stmt (gimple stmt
, edge
*taken_edge_p
)
2292 ccp_prop_value_t val
;
2295 block
= gimple_bb (stmt
);
2296 val
= evaluate_stmt (stmt
);
2297 if (val
.lattice_val
!= CONSTANT
2299 return SSA_PROP_VARYING
;
2301 /* Find which edge out of the conditional block will be taken and add it
2302 to the worklist. If no single edge can be determined statically,
2303 return SSA_PROP_VARYING to feed all the outgoing edges to the
2304 propagation engine. */
2305 *taken_edge_p
= find_taken_edge (block
, val
.value
);
2307 return SSA_PROP_INTERESTING
;
2309 return SSA_PROP_VARYING
;
2313 /* Evaluate statement STMT. If the statement produces an output value and
2314 its evaluation changes the lattice value of its output, return
2315 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
2318 If STMT is a conditional branch and we can determine its truth
2319 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
2320 value, return SSA_PROP_VARYING. */
2322 static enum ssa_prop_result
2323 ccp_visit_stmt (gimple stmt
, edge
*taken_edge_p
, tree
*output_p
)
2328 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2330 fprintf (dump_file
, "\nVisiting statement:\n");
2331 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2334 switch (gimple_code (stmt
))
2337 /* If the statement is an assignment that produces a single
2338 output value, evaluate its RHS to see if the lattice value of
2339 its output has changed. */
2340 return visit_assignment (stmt
, output_p
);
2343 /* A value-returning call also performs an assignment. */
2344 if (gimple_call_lhs (stmt
) != NULL_TREE
)
2345 return visit_assignment (stmt
, output_p
);
2350 /* If STMT is a conditional branch, see if we can determine
2351 which branch will be taken. */
2352 /* FIXME. It appears that we should be able to optimize
2353 computed GOTOs here as well. */
2354 return visit_cond_stmt (stmt
, taken_edge_p
);
2360 /* Any other kind of statement is not interesting for constant
2361 propagation and, therefore, not worth simulating. */
2362 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2363 fprintf (dump_file
, "No interesting values produced. Marked VARYING.\n");
2365 /* Definitions made by statements other than assignments to
2366 SSA_NAMEs represent unknown modifications to their outputs.
2367 Mark them VARYING. */
2368 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
2370 ccp_prop_value_t v
= { VARYING
, NULL_TREE
, -1 };
2371 set_lattice_value (def
, v
);
2374 return SSA_PROP_VARYING
;
2378 /* Main entry point for SSA Conditional Constant Propagation. */
2383 unsigned int todo
= 0;
2384 calculate_dominance_info (CDI_DOMINATORS
);
2386 ssa_propagate (ccp_visit_stmt
, ccp_visit_phi_node
);
2387 if (ccp_finalize ())
2388 todo
= (TODO_cleanup_cfg
| TODO_update_ssa
);
2389 free_dominance_info (CDI_DOMINATORS
);
2396 const pass_data pass_data_ccp
=
2398 GIMPLE_PASS
, /* type */
2400 OPTGROUP_NONE
, /* optinfo_flags */
2401 TV_TREE_CCP
, /* tv_id */
2402 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2403 0, /* properties_provided */
2404 0, /* properties_destroyed */
2405 0, /* todo_flags_start */
2406 TODO_update_address_taken
, /* todo_flags_finish */
2409 class pass_ccp
: public gimple_opt_pass
2412 pass_ccp (gcc::context
*ctxt
)
2413 : gimple_opt_pass (pass_data_ccp
, ctxt
)
2416 /* opt_pass methods: */
2417 opt_pass
* clone () { return new pass_ccp (m_ctxt
); }
2418 virtual bool gate (function
*) { return flag_tree_ccp
!= 0; }
2419 virtual unsigned int execute (function
*) { return do_ssa_ccp (); }
2421 }; // class pass_ccp
2426 make_pass_ccp (gcc::context
*ctxt
)
2428 return new pass_ccp (ctxt
);
2433 /* Try to optimize out __builtin_stack_restore. Optimize it out
2434 if there is another __builtin_stack_restore in the same basic
2435 block and no calls or ASM_EXPRs are in between, or if this block's
2436 only outgoing edge is to EXIT_BLOCK and there are no calls or
2437 ASM_EXPRs after this __builtin_stack_restore. */
2440 optimize_stack_restore (gimple_stmt_iterator i
)
2445 basic_block bb
= gsi_bb (i
);
2446 gimple call
= gsi_stmt (i
);
2448 if (gimple_code (call
) != GIMPLE_CALL
2449 || gimple_call_num_args (call
) != 1
2450 || TREE_CODE (gimple_call_arg (call
, 0)) != SSA_NAME
2451 || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call
, 0))))
2454 for (gsi_next (&i
); !gsi_end_p (i
); gsi_next (&i
))
2456 stmt
= gsi_stmt (i
);
2457 if (gimple_code (stmt
) == GIMPLE_ASM
)
2459 if (gimple_code (stmt
) != GIMPLE_CALL
)
2462 callee
= gimple_call_fndecl (stmt
);
2464 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2465 /* All regular builtins are ok, just obviously not alloca. */
2466 || DECL_FUNCTION_CODE (callee
) == BUILT_IN_ALLOCA
2467 || DECL_FUNCTION_CODE (callee
) == BUILT_IN_ALLOCA_WITH_ALIGN
)
2470 if (DECL_FUNCTION_CODE (callee
) == BUILT_IN_STACK_RESTORE
)
2471 goto second_stack_restore
;
2477 /* Allow one successor of the exit block, or zero successors. */
2478 switch (EDGE_COUNT (bb
->succs
))
2483 if (single_succ_edge (bb
)->dest
!= EXIT_BLOCK_PTR_FOR_FN (cfun
))
2489 second_stack_restore
:
2491 /* If there's exactly one use, then zap the call to __builtin_stack_save.
2492 If there are multiple uses, then the last one should remove the call.
2493 In any case, whether the call to __builtin_stack_save can be removed
2494 or not is irrelevant to removing the call to __builtin_stack_restore. */
2495 if (has_single_use (gimple_call_arg (call
, 0)))
2497 gimple stack_save
= SSA_NAME_DEF_STMT (gimple_call_arg (call
, 0));
2498 if (is_gimple_call (stack_save
))
2500 callee
= gimple_call_fndecl (stack_save
);
2502 && DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
2503 && DECL_FUNCTION_CODE (callee
) == BUILT_IN_STACK_SAVE
)
2505 gimple_stmt_iterator stack_save_gsi
;
2508 stack_save_gsi
= gsi_for_stmt (stack_save
);
2509 rhs
= build_int_cst (TREE_TYPE (gimple_call_arg (call
, 0)), 0);
2510 update_call_from_tree (&stack_save_gsi
, rhs
);
2515 /* No effect, so the statement will be deleted. */
2516 return integer_zero_node
;
2519 /* If va_list type is a simple pointer and nothing special is needed,
2520 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
2521 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
2522 pointer assignment. */
2525 optimize_stdarg_builtin (gimple call
)
2527 tree callee
, lhs
, rhs
, cfun_va_list
;
2528 bool va_list_simple_ptr
;
2529 location_t loc
= gimple_location (call
);
2531 if (gimple_code (call
) != GIMPLE_CALL
)
2534 callee
= gimple_call_fndecl (call
);
2536 cfun_va_list
= targetm
.fn_abi_va_list (callee
);
2537 va_list_simple_ptr
= POINTER_TYPE_P (cfun_va_list
)
2538 && (TREE_TYPE (cfun_va_list
) == void_type_node
2539 || TREE_TYPE (cfun_va_list
) == char_type_node
);
2541 switch (DECL_FUNCTION_CODE (callee
))
2543 case BUILT_IN_VA_START
:
2544 if (!va_list_simple_ptr
2545 || targetm
.expand_builtin_va_start
!= NULL
2546 || !builtin_decl_explicit_p (BUILT_IN_NEXT_ARG
))
2549 if (gimple_call_num_args (call
) != 2)
2552 lhs
= gimple_call_arg (call
, 0);
2553 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2554 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2555 != TYPE_MAIN_VARIANT (cfun_va_list
))
2558 lhs
= build_fold_indirect_ref_loc (loc
, lhs
);
2559 rhs
= build_call_expr_loc (loc
, builtin_decl_explicit (BUILT_IN_NEXT_ARG
),
2560 1, integer_zero_node
);
2561 rhs
= fold_convert_loc (loc
, TREE_TYPE (lhs
), rhs
);
2562 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2564 case BUILT_IN_VA_COPY
:
2565 if (!va_list_simple_ptr
)
2568 if (gimple_call_num_args (call
) != 2)
2571 lhs
= gimple_call_arg (call
, 0);
2572 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2573 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2574 != TYPE_MAIN_VARIANT (cfun_va_list
))
2577 lhs
= build_fold_indirect_ref_loc (loc
, lhs
);
2578 rhs
= gimple_call_arg (call
, 1);
2579 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs
))
2580 != TYPE_MAIN_VARIANT (cfun_va_list
))
2583 rhs
= fold_convert_loc (loc
, TREE_TYPE (lhs
), rhs
);
2584 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2586 case BUILT_IN_VA_END
:
2587 /* No effect, so the statement will be deleted. */
2588 return integer_zero_node
;
2595 /* Attemp to make the block of __builtin_unreachable I unreachable by changing
2596 the incoming jumps. Return true if at least one jump was changed. */
2599 optimize_unreachable (gimple_stmt_iterator i
)
2601 basic_block bb
= gsi_bb (i
);
2602 gimple_stmt_iterator gsi
;
2608 if (flag_sanitize
& SANITIZE_UNREACHABLE
)
2611 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
2613 stmt
= gsi_stmt (gsi
);
2615 if (is_gimple_debug (stmt
))
2618 if (glabel
*label_stmt
= dyn_cast
<glabel
*> (stmt
))
2620 /* Verify we do not need to preserve the label. */
2621 if (FORCED_LABEL (gimple_label_label (label_stmt
)))
2627 /* Only handle the case that __builtin_unreachable is the first statement
2628 in the block. We rely on DCE to remove stmts without side-effects
2629 before __builtin_unreachable. */
2630 if (gsi_stmt (gsi
) != gsi_stmt (i
))
2635 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
2637 gsi
= gsi_last_bb (e
->src
);
2638 if (gsi_end_p (gsi
))
2641 stmt
= gsi_stmt (gsi
);
2642 if (gcond
*cond_stmt
= dyn_cast
<gcond
*> (stmt
))
2644 if (e
->flags
& EDGE_TRUE_VALUE
)
2645 gimple_cond_make_false (cond_stmt
);
2646 else if (e
->flags
& EDGE_FALSE_VALUE
)
2647 gimple_cond_make_true (cond_stmt
);
2650 update_stmt (cond_stmt
);
2654 /* Todo: handle other cases, f.i. switch statement. */
2664 /* A simple pass that attempts to fold all builtin functions. This pass
2665 is run after we've propagated as many constants as we can. */
2669 const pass_data pass_data_fold_builtins
=
2671 GIMPLE_PASS
, /* type */
2673 OPTGROUP_NONE
, /* optinfo_flags */
2674 TV_NONE
, /* tv_id */
2675 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2676 0, /* properties_provided */
2677 0, /* properties_destroyed */
2678 0, /* todo_flags_start */
2679 TODO_update_ssa
, /* todo_flags_finish */
2682 class pass_fold_builtins
: public gimple_opt_pass
2685 pass_fold_builtins (gcc::context
*ctxt
)
2686 : gimple_opt_pass (pass_data_fold_builtins
, ctxt
)
2689 /* opt_pass methods: */
2690 opt_pass
* clone () { return new pass_fold_builtins (m_ctxt
); }
2691 virtual unsigned int execute (function
*);
2693 }; // class pass_fold_builtins
2696 pass_fold_builtins::execute (function
*fun
)
2698 bool cfg_changed
= false;
2700 unsigned int todoflags
= 0;
2702 FOR_EACH_BB_FN (bb
, fun
)
2704 gimple_stmt_iterator i
;
2705 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); )
2707 gimple stmt
, old_stmt
;
2709 enum built_in_function fcode
;
2711 stmt
= gsi_stmt (i
);
2713 if (gimple_code (stmt
) != GIMPLE_CALL
)
2715 /* Remove all *ssaname_N ={v} {CLOBBER}; stmts,
2716 after the last GIMPLE DSE they aren't needed and might
2717 unnecessarily keep the SSA_NAMEs live. */
2718 if (gimple_clobber_p (stmt
))
2720 tree lhs
= gimple_assign_lhs (stmt
);
2721 if (TREE_CODE (lhs
) == MEM_REF
2722 && TREE_CODE (TREE_OPERAND (lhs
, 0)) == SSA_NAME
)
2724 unlink_stmt_vdef (stmt
);
2725 gsi_remove (&i
, true);
2726 release_defs (stmt
);
2734 callee
= gimple_call_fndecl (stmt
);
2735 if (!callee
|| DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
)
2741 fcode
= DECL_FUNCTION_CODE (callee
);
2746 tree result
= NULL_TREE
;
2747 switch (DECL_FUNCTION_CODE (callee
))
2749 case BUILT_IN_CONSTANT_P
:
2750 /* Resolve __builtin_constant_p. If it hasn't been
2751 folded to integer_one_node by now, it's fairly
2752 certain that the value simply isn't constant. */
2753 result
= integer_zero_node
;
2756 case BUILT_IN_ASSUME_ALIGNED
:
2757 /* Remove __builtin_assume_aligned. */
2758 result
= gimple_call_arg (stmt
, 0);
2761 case BUILT_IN_STACK_RESTORE
:
2762 result
= optimize_stack_restore (i
);
2768 case BUILT_IN_UNREACHABLE
:
2769 if (optimize_unreachable (i
))
2773 case BUILT_IN_VA_START
:
2774 case BUILT_IN_VA_END
:
2775 case BUILT_IN_VA_COPY
:
2776 /* These shouldn't be folded before pass_stdarg. */
2777 result
= optimize_stdarg_builtin (stmt
);
2791 if (!update_call_from_tree (&i
, result
))
2792 gimplify_and_update_call_from_tree (&i
, result
);
2795 todoflags
|= TODO_update_address_taken
;
2797 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2799 fprintf (dump_file
, "Simplified\n ");
2800 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2804 stmt
= gsi_stmt (i
);
2807 if (maybe_clean_or_replace_eh_stmt (old_stmt
, stmt
)
2808 && gimple_purge_dead_eh_edges (bb
))
2811 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2813 fprintf (dump_file
, "to\n ");
2814 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2815 fprintf (dump_file
, "\n");
2818 /* Retry the same statement if it changed into another
2819 builtin, there might be new opportunities now. */
2820 if (gimple_code (stmt
) != GIMPLE_CALL
)
2825 callee
= gimple_call_fndecl (stmt
);
2827 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2828 || DECL_FUNCTION_CODE (callee
) == fcode
)
2833 /* Delete unreachable blocks. */
2835 todoflags
|= TODO_cleanup_cfg
;
2843 make_pass_fold_builtins (gcc::context
*ctxt
)
2845 return new pass_fold_builtins (ctxt
);