1 /* Conditional constant propagation pass for the GNU compiler.
2 Copyright (C) 2000-2013 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.
103 Constant propagation with conditional branches,
104 Wegman and Zadeck, ACM TOPLAS 13(2):181-210.
106 Building an Optimizing Compiler,
107 Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9.
109 Advanced Compiler Design and Implementation,
110 Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */
114 #include "coretypes.h"
119 #include "basic-block.h"
120 #include "function.h"
121 #include "gimple-pretty-print.h"
122 #include "tree-flow.h"
123 #include "tree-pass.h"
124 #include "tree-ssa-propagate.h"
125 #include "value-prof.h"
126 #include "langhooks.h"
128 #include "diagnostic-core.h"
130 #include "gimple-fold.h"
132 #include "hash-table.h"
135 /* Possible lattice values. */
144 struct prop_value_d
{
146 ccp_lattice_t lattice_val
;
148 /* Propagated value. */
151 /* Mask that applies to the propagated value during CCP. For
152 X with a CONSTANT lattice value X & ~mask == value & ~mask. */
156 typedef struct prop_value_d prop_value_t
;
158 /* Array of propagated constant values. After propagation,
159 CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If
160 the constant is held in an SSA name representing a memory store
161 (i.e., a VDEF), CONST_VAL[I].MEM_REF will contain the actual
162 memory reference used to store (i.e., the LHS of the assignment
164 static prop_value_t
*const_val
;
165 static unsigned n_const_val
;
167 static void canonicalize_float_value (prop_value_t
*);
168 static bool ccp_fold_stmt (gimple_stmt_iterator
*);
170 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */
173 dump_lattice_value (FILE *outf
, const char *prefix
, prop_value_t val
)
175 switch (val
.lattice_val
)
178 fprintf (outf
, "%sUNINITIALIZED", prefix
);
181 fprintf (outf
, "%sUNDEFINED", prefix
);
184 fprintf (outf
, "%sVARYING", prefix
);
187 if (TREE_CODE (val
.value
) != INTEGER_CST
188 || val
.mask
.is_zero ())
190 fprintf (outf
, "%sCONSTANT ", prefix
);
191 print_generic_expr (outf
, val
.value
, dump_flags
);
195 double_int cval
= tree_to_double_int (val
.value
).and_not (val
.mask
);
196 fprintf (outf
, "%sCONSTANT " HOST_WIDE_INT_PRINT_DOUBLE_HEX
,
197 prefix
, cval
.high
, cval
.low
);
198 fprintf (outf
, " (" HOST_WIDE_INT_PRINT_DOUBLE_HEX
")",
199 val
.mask
.high
, val
.mask
.low
);
208 /* Print lattice value VAL to stderr. */
210 void debug_lattice_value (prop_value_t val
);
213 debug_lattice_value (prop_value_t val
)
215 dump_lattice_value (stderr
, "", val
);
216 fprintf (stderr
, "\n");
220 /* Compute a default value for variable VAR and store it in the
221 CONST_VAL array. The following rules are used to get default
224 1- Global and static variables that are declared constant are
227 2- Any other value is considered UNDEFINED. This is useful when
228 considering PHI nodes. PHI arguments that are undefined do not
229 change the constant value of the PHI node, which allows for more
230 constants to be propagated.
232 3- Variables defined by statements other than assignments and PHI
233 nodes are considered VARYING.
235 4- Initial values of variables that are not GIMPLE registers are
236 considered VARYING. */
239 get_default_value (tree var
)
241 prop_value_t val
= { UNINITIALIZED
, NULL_TREE
, { 0, 0 } };
244 stmt
= SSA_NAME_DEF_STMT (var
);
246 if (gimple_nop_p (stmt
))
248 /* Variables defined by an empty statement are those used
249 before being initialized. If VAR is a local variable, we
250 can assume initially that it is UNDEFINED, otherwise we must
251 consider it VARYING. */
252 if (!virtual_operand_p (var
)
253 && TREE_CODE (SSA_NAME_VAR (var
)) == VAR_DECL
)
254 val
.lattice_val
= UNDEFINED
;
257 val
.lattice_val
= VARYING
;
258 val
.mask
= double_int_minus_one
;
261 else if (is_gimple_assign (stmt
))
264 if (gimple_assign_single_p (stmt
)
265 && DECL_P (gimple_assign_rhs1 (stmt
))
266 && (cst
= get_symbol_constant_value (gimple_assign_rhs1 (stmt
))))
268 val
.lattice_val
= CONSTANT
;
273 /* Any other variable defined by an assignment is considered
275 val
.lattice_val
= UNDEFINED
;
278 else if ((is_gimple_call (stmt
)
279 && gimple_call_lhs (stmt
) != NULL_TREE
)
280 || gimple_code (stmt
) == GIMPLE_PHI
)
282 /* A variable defined by a call or a PHI node is considered
284 val
.lattice_val
= UNDEFINED
;
288 /* Otherwise, VAR will never take on a constant value. */
289 val
.lattice_val
= VARYING
;
290 val
.mask
= double_int_minus_one
;
297 /* Get the constant value associated with variable VAR. */
299 static inline prop_value_t
*
304 if (const_val
== NULL
305 || SSA_NAME_VERSION (var
) >= n_const_val
)
308 val
= &const_val
[SSA_NAME_VERSION (var
)];
309 if (val
->lattice_val
== UNINITIALIZED
)
310 *val
= get_default_value (var
);
312 canonicalize_float_value (val
);
317 /* Return the constant tree value associated with VAR. */
320 get_constant_value (tree var
)
323 if (TREE_CODE (var
) != SSA_NAME
)
325 if (is_gimple_min_invariant (var
))
329 val
= get_value (var
);
331 && val
->lattice_val
== CONSTANT
332 && (TREE_CODE (val
->value
) != INTEGER_CST
333 || val
->mask
.is_zero ()))
338 /* Sets the value associated with VAR to VARYING. */
341 set_value_varying (tree var
)
343 prop_value_t
*val
= &const_val
[SSA_NAME_VERSION (var
)];
345 val
->lattice_val
= VARYING
;
346 val
->value
= NULL_TREE
;
347 val
->mask
= double_int_minus_one
;
350 /* For float types, modify the value of VAL to make ccp work correctly
351 for non-standard values (-0, NaN):
353 If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0.
354 If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED.
355 This is to fix the following problem (see PR 29921): Suppose we have
359 and we set value of y to NaN. This causes value of x to be set to NaN.
360 When we later determine that y is in fact VARYING, fold uses the fact
361 that HONOR_NANS is false, and we try to change the value of x to 0,
362 causing an ICE. With HONOR_NANS being false, the real appearance of
363 NaN would cause undefined behavior, though, so claiming that y (and x)
364 are UNDEFINED initially is correct. */
367 canonicalize_float_value (prop_value_t
*val
)
369 enum machine_mode mode
;
373 if (val
->lattice_val
!= CONSTANT
374 || TREE_CODE (val
->value
) != REAL_CST
)
377 d
= TREE_REAL_CST (val
->value
);
378 type
= TREE_TYPE (val
->value
);
379 mode
= TYPE_MODE (type
);
381 if (!HONOR_SIGNED_ZEROS (mode
)
382 && REAL_VALUE_MINUS_ZERO (d
))
384 val
->value
= build_real (type
, dconst0
);
388 if (!HONOR_NANS (mode
)
389 && REAL_VALUE_ISNAN (d
))
391 val
->lattice_val
= UNDEFINED
;
397 /* Return whether the lattice transition is valid. */
400 valid_lattice_transition (prop_value_t old_val
, prop_value_t new_val
)
402 /* Lattice transitions must always be monotonically increasing in
404 if (old_val
.lattice_val
< new_val
.lattice_val
)
407 if (old_val
.lattice_val
!= new_val
.lattice_val
)
410 if (!old_val
.value
&& !new_val
.value
)
413 /* Now both lattice values are CONSTANT. */
415 /* Allow transitioning from PHI <&x, not executable> == &x
416 to PHI <&x, &y> == common alignment. */
417 if (TREE_CODE (old_val
.value
) != INTEGER_CST
418 && TREE_CODE (new_val
.value
) == INTEGER_CST
)
421 /* Bit-lattices have to agree in the still valid bits. */
422 if (TREE_CODE (old_val
.value
) == INTEGER_CST
423 && TREE_CODE (new_val
.value
) == INTEGER_CST
)
424 return tree_to_double_int (old_val
.value
).and_not (new_val
.mask
)
425 == tree_to_double_int (new_val
.value
).and_not (new_val
.mask
);
427 /* Otherwise constant values have to agree. */
428 return operand_equal_p (old_val
.value
, new_val
.value
, 0);
431 /* Set the value for variable VAR to NEW_VAL. Return true if the new
432 value is different from VAR's previous value. */
435 set_lattice_value (tree var
, prop_value_t new_val
)
437 /* We can deal with old UNINITIALIZED values just fine here. */
438 prop_value_t
*old_val
= &const_val
[SSA_NAME_VERSION (var
)];
440 canonicalize_float_value (&new_val
);
442 /* We have to be careful to not go up the bitwise lattice
443 represented by the mask.
444 ??? This doesn't seem to be the best place to enforce this. */
445 if (new_val
.lattice_val
== CONSTANT
446 && old_val
->lattice_val
== CONSTANT
447 && TREE_CODE (new_val
.value
) == INTEGER_CST
448 && TREE_CODE (old_val
->value
) == INTEGER_CST
)
451 diff
= tree_to_double_int (new_val
.value
)
452 ^ tree_to_double_int (old_val
->value
);
453 new_val
.mask
= new_val
.mask
| old_val
->mask
| diff
;
456 gcc_assert (valid_lattice_transition (*old_val
, new_val
));
458 /* If *OLD_VAL and NEW_VAL are the same, return false to inform the
459 caller that this was a non-transition. */
460 if (old_val
->lattice_val
!= new_val
.lattice_val
461 || (new_val
.lattice_val
== CONSTANT
462 && TREE_CODE (new_val
.value
) == INTEGER_CST
463 && (TREE_CODE (old_val
->value
) != INTEGER_CST
464 || new_val
.mask
!= old_val
->mask
)))
466 /* ??? We would like to delay creation of INTEGER_CSTs from
467 partially constants here. */
469 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
471 dump_lattice_value (dump_file
, "Lattice value changed to ", new_val
);
472 fprintf (dump_file
, ". Adding SSA edges to worklist.\n");
477 gcc_assert (new_val
.lattice_val
!= UNINITIALIZED
);
484 static prop_value_t
get_value_for_expr (tree
, bool);
485 static prop_value_t
bit_value_binop (enum tree_code
, tree
, tree
, tree
);
486 static void bit_value_binop_1 (enum tree_code
, tree
, double_int
*, double_int
*,
487 tree
, double_int
, double_int
,
488 tree
, double_int
, double_int
);
490 /* Return a double_int that can be used for bitwise simplifications
494 value_to_double_int (prop_value_t val
)
497 && TREE_CODE (val
.value
) == INTEGER_CST
)
498 return tree_to_double_int (val
.value
);
500 return double_int_zero
;
503 /* Return the value for the address expression EXPR based on alignment
507 get_value_from_alignment (tree expr
)
509 tree type
= TREE_TYPE (expr
);
511 unsigned HOST_WIDE_INT bitpos
;
514 gcc_assert (TREE_CODE (expr
) == ADDR_EXPR
);
516 get_pointer_alignment_1 (expr
, &align
, &bitpos
);
517 val
.mask
= (POINTER_TYPE_P (type
) || TYPE_UNSIGNED (type
)
518 ? double_int::mask (TYPE_PRECISION (type
))
519 : double_int_minus_one
)
520 .and_not (double_int::from_uhwi (align
/ BITS_PER_UNIT
- 1));
521 val
.lattice_val
= val
.mask
.is_minus_one () ? VARYING
: CONSTANT
;
522 if (val
.lattice_val
== CONSTANT
)
524 = double_int_to_tree (type
,
525 double_int::from_uhwi (bitpos
/ BITS_PER_UNIT
));
527 val
.value
= NULL_TREE
;
532 /* Return the value for the tree operand EXPR. If FOR_BITS_P is true
533 return constant bits extracted from alignment information for
534 invariant addresses. */
537 get_value_for_expr (tree expr
, bool for_bits_p
)
541 if (TREE_CODE (expr
) == SSA_NAME
)
543 val
= *get_value (expr
);
545 && val
.lattice_val
== CONSTANT
546 && TREE_CODE (val
.value
) == ADDR_EXPR
)
547 val
= get_value_from_alignment (val
.value
);
549 else if (is_gimple_min_invariant (expr
)
550 && (!for_bits_p
|| TREE_CODE (expr
) != ADDR_EXPR
))
552 val
.lattice_val
= CONSTANT
;
554 val
.mask
= double_int_zero
;
555 canonicalize_float_value (&val
);
557 else if (TREE_CODE (expr
) == ADDR_EXPR
)
558 val
= get_value_from_alignment (expr
);
561 val
.lattice_val
= VARYING
;
562 val
.mask
= double_int_minus_one
;
563 val
.value
= NULL_TREE
;
568 /* Return the likely CCP lattice value for STMT.
570 If STMT has no operands, then return CONSTANT.
572 Else if undefinedness of operands of STMT cause its value to be
573 undefined, then return UNDEFINED.
575 Else if any operands of STMT are constants, then return CONSTANT.
577 Else return VARYING. */
580 likely_value (gimple stmt
)
582 bool has_constant_operand
, has_undefined_operand
, all_undefined_operands
;
587 enum gimple_code code
= gimple_code (stmt
);
589 /* This function appears to be called only for assignments, calls,
590 conditionals, and switches, due to the logic in visit_stmt. */
591 gcc_assert (code
== GIMPLE_ASSIGN
592 || code
== GIMPLE_CALL
593 || code
== GIMPLE_COND
594 || code
== GIMPLE_SWITCH
);
596 /* If the statement has volatile operands, it won't fold to a
598 if (gimple_has_volatile_ops (stmt
))
601 /* Arrive here for more complex cases. */
602 has_constant_operand
= false;
603 has_undefined_operand
= false;
604 all_undefined_operands
= true;
605 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, iter
, SSA_OP_USE
)
607 prop_value_t
*val
= get_value (use
);
609 if (val
->lattice_val
== UNDEFINED
)
610 has_undefined_operand
= true;
612 all_undefined_operands
= false;
614 if (val
->lattice_val
== CONSTANT
)
615 has_constant_operand
= true;
618 /* There may be constants in regular rhs operands. For calls we
619 have to ignore lhs, fndecl and static chain, otherwise only
621 for (i
= (is_gimple_call (stmt
) ? 2 : 0) + gimple_has_lhs (stmt
);
622 i
< gimple_num_ops (stmt
); ++i
)
624 tree op
= gimple_op (stmt
, i
);
625 if (!op
|| TREE_CODE (op
) == SSA_NAME
)
627 if (is_gimple_min_invariant (op
))
628 has_constant_operand
= true;
631 if (has_constant_operand
)
632 all_undefined_operands
= false;
634 /* If the operation combines operands like COMPLEX_EXPR make sure to
635 not mark the result UNDEFINED if only one part of the result is
637 if (has_undefined_operand
&& all_undefined_operands
)
639 else if (code
== GIMPLE_ASSIGN
&& has_undefined_operand
)
641 switch (gimple_assign_rhs_code (stmt
))
643 /* Unary operators are handled with all_undefined_operands. */
646 case POINTER_PLUS_EXPR
:
647 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected.
648 Not bitwise operators, one VARYING operand may specify the
649 result completely. Not logical operators for the same reason.
650 Not COMPLEX_EXPR as one VARYING operand makes the result partly
651 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because
652 the undefined operand may be promoted. */
656 /* If any part of an address is UNDEFINED, like the index
657 of an ARRAY_EXPR, then treat the result as UNDEFINED. */
664 /* If there was an UNDEFINED operand but the result may be not UNDEFINED
665 fall back to CONSTANT. During iteration UNDEFINED may still drop
667 if (has_undefined_operand
)
670 /* We do not consider virtual operands here -- load from read-only
671 memory may have only VARYING virtual operands, but still be
673 if (has_constant_operand
674 || gimple_references_memory_p (stmt
))
680 /* Returns true if STMT cannot be constant. */
683 surely_varying_stmt_p (gimple stmt
)
685 /* If the statement has operands that we cannot handle, it cannot be
687 if (gimple_has_volatile_ops (stmt
))
690 /* If it is a call and does not return a value or is not a
691 builtin and not an indirect call, it is varying. */
692 if (is_gimple_call (stmt
))
695 if (!gimple_call_lhs (stmt
)
696 || ((fndecl
= gimple_call_fndecl (stmt
)) != NULL_TREE
697 && !DECL_BUILT_IN (fndecl
)))
701 /* Any other store operation is not interesting. */
702 else if (gimple_vdef (stmt
))
705 /* Anything other than assignments and conditional jumps are not
706 interesting for CCP. */
707 if (gimple_code (stmt
) != GIMPLE_ASSIGN
708 && gimple_code (stmt
) != GIMPLE_COND
709 && gimple_code (stmt
) != GIMPLE_SWITCH
710 && gimple_code (stmt
) != GIMPLE_CALL
)
716 /* Initialize local data structures for CCP. */
719 ccp_initialize (void)
723 n_const_val
= num_ssa_names
;
724 const_val
= XCNEWVEC (prop_value_t
, n_const_val
);
726 /* Initialize simulation flags for PHI nodes and statements. */
729 gimple_stmt_iterator i
;
731 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); gsi_next (&i
))
733 gimple stmt
= gsi_stmt (i
);
736 /* If the statement is a control insn, then we do not
737 want to avoid simulating the statement once. Failure
738 to do so means that those edges will never get added. */
739 if (stmt_ends_bb_p (stmt
))
742 is_varying
= surely_varying_stmt_p (stmt
);
749 /* If the statement will not produce a constant, mark
750 all its outputs VARYING. */
751 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
752 set_value_varying (def
);
754 prop_set_simulate_again (stmt
, !is_varying
);
758 /* Now process PHI nodes. We never clear the simulate_again flag on
759 phi nodes, since we do not know which edges are executable yet,
760 except for phi nodes for virtual operands when we do not do store ccp. */
763 gimple_stmt_iterator i
;
765 for (i
= gsi_start_phis (bb
); !gsi_end_p (i
); gsi_next (&i
))
767 gimple phi
= gsi_stmt (i
);
769 if (virtual_operand_p (gimple_phi_result (phi
)))
770 prop_set_simulate_again (phi
, false);
772 prop_set_simulate_again (phi
, true);
777 /* Debug count support. Reset the values of ssa names
778 VARYING when the total number ssa names analyzed is
779 beyond the debug count specified. */
785 for (i
= 0; i
< num_ssa_names
; i
++)
789 const_val
[i
].lattice_val
= VARYING
;
790 const_val
[i
].mask
= double_int_minus_one
;
791 const_val
[i
].value
= NULL_TREE
;
797 /* Do final substitution of propagated values, cleanup the flowgraph and
798 free allocated storage.
800 Return TRUE when something was optimized. */
805 bool something_changed
;
810 /* Derive alignment and misalignment information from partially
811 constant pointers in the lattice. */
812 for (i
= 1; i
< num_ssa_names
; ++i
)
814 tree name
= ssa_name (i
);
816 unsigned int tem
, align
;
819 || !POINTER_TYPE_P (TREE_TYPE (name
)))
822 val
= get_value (name
);
823 if (val
->lattice_val
!= CONSTANT
824 || TREE_CODE (val
->value
) != INTEGER_CST
)
827 /* Trailing constant bits specify the alignment, trailing value
828 bits the misalignment. */
830 align
= (tem
& -tem
);
832 set_ptr_info_alignment (get_ptr_info (name
), align
,
833 TREE_INT_CST_LOW (val
->value
) & (align
- 1));
836 /* Perform substitutions based on the known constant values. */
837 something_changed
= substitute_and_fold (get_constant_value
,
838 ccp_fold_stmt
, true);
842 return something_changed
;;
846 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
849 any M UNDEFINED = any
850 any M VARYING = VARYING
851 Ci M Cj = Ci if (i == j)
852 Ci M Cj = VARYING if (i != j)
856 ccp_lattice_meet (prop_value_t
*val1
, prop_value_t
*val2
)
858 if (val1
->lattice_val
== UNDEFINED
)
860 /* UNDEFINED M any = any */
863 else if (val2
->lattice_val
== UNDEFINED
)
865 /* any M UNDEFINED = any
866 Nothing to do. VAL1 already contains the value we want. */
869 else if (val1
->lattice_val
== VARYING
870 || val2
->lattice_val
== VARYING
)
872 /* any M VARYING = VARYING. */
873 val1
->lattice_val
= VARYING
;
874 val1
->mask
= double_int_minus_one
;
875 val1
->value
= NULL_TREE
;
877 else if (val1
->lattice_val
== CONSTANT
878 && val2
->lattice_val
== CONSTANT
879 && TREE_CODE (val1
->value
) == INTEGER_CST
880 && TREE_CODE (val2
->value
) == INTEGER_CST
)
882 /* Ci M Cj = Ci if (i == j)
883 Ci M Cj = VARYING if (i != j)
885 For INTEGER_CSTs mask unequal bits. If no equal bits remain,
887 val1
->mask
= val1
->mask
| val2
->mask
888 | (tree_to_double_int (val1
->value
)
889 ^ tree_to_double_int (val2
->value
));
890 if (val1
->mask
.is_minus_one ())
892 val1
->lattice_val
= VARYING
;
893 val1
->value
= NULL_TREE
;
896 else if (val1
->lattice_val
== CONSTANT
897 && val2
->lattice_val
== CONSTANT
898 && simple_cst_equal (val1
->value
, val2
->value
) == 1)
900 /* Ci M Cj = Ci if (i == j)
901 Ci M Cj = VARYING if (i != j)
903 VAL1 already contains the value we want for equivalent values. */
905 else if (val1
->lattice_val
== CONSTANT
906 && val2
->lattice_val
== CONSTANT
907 && (TREE_CODE (val1
->value
) == ADDR_EXPR
908 || TREE_CODE (val2
->value
) == ADDR_EXPR
))
910 /* When not equal addresses are involved try meeting for
912 prop_value_t tem
= *val2
;
913 if (TREE_CODE (val1
->value
) == ADDR_EXPR
)
914 *val1
= get_value_for_expr (val1
->value
, true);
915 if (TREE_CODE (val2
->value
) == ADDR_EXPR
)
916 tem
= get_value_for_expr (val2
->value
, true);
917 ccp_lattice_meet (val1
, &tem
);
921 /* Any other combination is VARYING. */
922 val1
->lattice_val
= VARYING
;
923 val1
->mask
= double_int_minus_one
;
924 val1
->value
= NULL_TREE
;
929 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
930 lattice values to determine PHI_NODE's lattice value. The value of a
931 PHI node is determined calling ccp_lattice_meet with all the arguments
932 of the PHI node that are incoming via executable edges. */
934 static enum ssa_prop_result
935 ccp_visit_phi_node (gimple phi
)
938 prop_value_t
*old_val
, new_val
;
940 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
942 fprintf (dump_file
, "\nVisiting PHI node: ");
943 print_gimple_stmt (dump_file
, phi
, 0, dump_flags
);
946 old_val
= get_value (gimple_phi_result (phi
));
947 switch (old_val
->lattice_val
)
950 return SSA_PROP_VARYING
;
957 new_val
.lattice_val
= UNDEFINED
;
958 new_val
.value
= NULL_TREE
;
965 for (i
= 0; i
< gimple_phi_num_args (phi
); i
++)
967 /* Compute the meet operator over all the PHI arguments flowing
968 through executable edges. */
969 edge e
= gimple_phi_arg_edge (phi
, i
);
971 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
974 "\n Argument #%d (%d -> %d %sexecutable)\n",
975 i
, e
->src
->index
, e
->dest
->index
,
976 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
979 /* If the incoming edge is executable, Compute the meet operator for
980 the existing value of the PHI node and the current PHI argument. */
981 if (e
->flags
& EDGE_EXECUTABLE
)
983 tree arg
= gimple_phi_arg (phi
, i
)->def
;
984 prop_value_t arg_val
= get_value_for_expr (arg
, false);
986 ccp_lattice_meet (&new_val
, &arg_val
);
988 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
990 fprintf (dump_file
, "\t");
991 print_generic_expr (dump_file
, arg
, dump_flags
);
992 dump_lattice_value (dump_file
, "\tValue: ", arg_val
);
993 fprintf (dump_file
, "\n");
996 if (new_val
.lattice_val
== VARYING
)
1001 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1003 dump_lattice_value (dump_file
, "\n PHI node value: ", new_val
);
1004 fprintf (dump_file
, "\n\n");
1007 /* Make the transition to the new value. */
1008 if (set_lattice_value (gimple_phi_result (phi
), new_val
))
1010 if (new_val
.lattice_val
== VARYING
)
1011 return SSA_PROP_VARYING
;
1013 return SSA_PROP_INTERESTING
;
1016 return SSA_PROP_NOT_INTERESTING
;
1019 /* Return the constant value for OP or OP otherwise. */
1022 valueize_op (tree op
)
1024 if (TREE_CODE (op
) == SSA_NAME
)
1026 tree tem
= get_constant_value (op
);
1033 /* CCP specific front-end to the non-destructive constant folding
1036 Attempt to simplify the RHS of STMT knowing that one or more
1037 operands are constants.
1039 If simplification is possible, return the simplified RHS,
1040 otherwise return the original RHS or NULL_TREE. */
1043 ccp_fold (gimple stmt
)
1045 location_t loc
= gimple_location (stmt
);
1046 switch (gimple_code (stmt
))
1050 /* Handle comparison operators that can appear in GIMPLE form. */
1051 tree op0
= valueize_op (gimple_cond_lhs (stmt
));
1052 tree op1
= valueize_op (gimple_cond_rhs (stmt
));
1053 enum tree_code code
= gimple_cond_code (stmt
);
1054 return fold_binary_loc (loc
, code
, boolean_type_node
, op0
, op1
);
1059 /* Return the constant switch index. */
1060 return valueize_op (gimple_switch_index (stmt
));
1065 return gimple_fold_stmt_to_constant_1 (stmt
, valueize_op
);
1072 /* Apply the operation CODE in type TYPE to the value, mask pair
1073 RVAL and RMASK representing a value of type RTYPE and set
1074 the value, mask pair *VAL and *MASK to the result. */
1077 bit_value_unop_1 (enum tree_code code
, tree type
,
1078 double_int
*val
, double_int
*mask
,
1079 tree rtype
, double_int rval
, double_int rmask
)
1090 double_int temv
, temm
;
1091 /* Return ~rval + 1. */
1092 bit_value_unop_1 (BIT_NOT_EXPR
, type
, &temv
, &temm
, type
, rval
, rmask
);
1093 bit_value_binop_1 (PLUS_EXPR
, type
, val
, mask
,
1095 type
, double_int_one
, double_int_zero
);
1103 /* First extend mask and value according to the original type. */
1104 uns
= TYPE_UNSIGNED (rtype
);
1105 *mask
= rmask
.ext (TYPE_PRECISION (rtype
), uns
);
1106 *val
= rval
.ext (TYPE_PRECISION (rtype
), uns
);
1108 /* Then extend mask and value according to the target type. */
1109 uns
= TYPE_UNSIGNED (type
);
1110 *mask
= (*mask
).ext (TYPE_PRECISION (type
), uns
);
1111 *val
= (*val
).ext (TYPE_PRECISION (type
), uns
);
1116 *mask
= double_int_minus_one
;
1121 /* Apply the operation CODE in type TYPE to the value, mask pairs
1122 R1VAL, R1MASK and R2VAL, R2MASK representing a values of type R1TYPE
1123 and R2TYPE and set the value, mask pair *VAL and *MASK to the result. */
1126 bit_value_binop_1 (enum tree_code code
, tree type
,
1127 double_int
*val
, double_int
*mask
,
1128 tree r1type
, double_int r1val
, double_int r1mask
,
1129 tree r2type
, double_int r2val
, double_int r2mask
)
1131 bool uns
= TYPE_UNSIGNED (type
);
1132 /* Assume we'll get a constant result. Use an initial varying value,
1133 we fall back to varying in the end if necessary. */
1134 *mask
= double_int_minus_one
;
1138 /* The mask is constant where there is a known not
1139 set bit, (m1 | m2) & ((v1 | m1) & (v2 | m2)) */
1140 *mask
= (r1mask
| r2mask
) & (r1val
| r1mask
) & (r2val
| r2mask
);
1141 *val
= r1val
& r2val
;
1145 /* The mask is constant where there is a known
1146 set bit, (m1 | m2) & ~((v1 & ~m1) | (v2 & ~m2)). */
1147 *mask
= (r1mask
| r2mask
)
1148 .and_not (r1val
.and_not (r1mask
) | r2val
.and_not (r2mask
));
1149 *val
= r1val
| r2val
;
1154 *mask
= r1mask
| r2mask
;
1155 *val
= r1val
^ r2val
;
1160 if (r2mask
.is_zero ())
1162 HOST_WIDE_INT shift
= r2val
.low
;
1163 if (code
== RROTATE_EXPR
)
1165 *mask
= r1mask
.lrotate (shift
, TYPE_PRECISION (type
));
1166 *val
= r1val
.lrotate (shift
, TYPE_PRECISION (type
));
1172 /* ??? We can handle partially known shift counts if we know
1173 its sign. That way we can tell that (x << (y | 8)) & 255
1175 if (r2mask
.is_zero ())
1177 HOST_WIDE_INT shift
= r2val
.low
;
1178 if (code
== RSHIFT_EXPR
)
1180 /* We need to know if we are doing a left or a right shift
1181 to properly shift in zeros for left shift and unsigned
1182 right shifts and the sign bit for signed right shifts.
1183 For signed right shifts we shift in varying in case
1184 the sign bit was varying. */
1187 *mask
= r1mask
.llshift (shift
, TYPE_PRECISION (type
));
1188 *val
= r1val
.llshift (shift
, TYPE_PRECISION (type
));
1193 *mask
= r1mask
.rshift (shift
, TYPE_PRECISION (type
), !uns
);
1194 *val
= r1val
.rshift (shift
, TYPE_PRECISION (type
), !uns
);
1205 case POINTER_PLUS_EXPR
:
1208 /* Do the addition with unknown bits set to zero, to give carry-ins of
1209 zero wherever possible. */
1210 lo
= r1val
.and_not (r1mask
) + r2val
.and_not (r2mask
);
1211 lo
= lo
.ext (TYPE_PRECISION (type
), uns
);
1212 /* Do the addition with unknown bits set to one, to give carry-ins of
1213 one wherever possible. */
1214 hi
= (r1val
| r1mask
) + (r2val
| r2mask
);
1215 hi
= hi
.ext (TYPE_PRECISION (type
), uns
);
1216 /* Each bit in the result is known if (a) the corresponding bits in
1217 both inputs are known, and (b) the carry-in to that bit position
1218 is known. We can check condition (b) by seeing if we got the same
1219 result with minimised carries as with maximised carries. */
1220 *mask
= r1mask
| r2mask
| (lo
^ hi
);
1221 *mask
= (*mask
).ext (TYPE_PRECISION (type
), uns
);
1222 /* It shouldn't matter whether we choose lo or hi here. */
1229 double_int temv
, temm
;
1230 bit_value_unop_1 (NEGATE_EXPR
, r2type
, &temv
, &temm
,
1231 r2type
, r2val
, r2mask
);
1232 bit_value_binop_1 (PLUS_EXPR
, type
, val
, mask
,
1233 r1type
, r1val
, r1mask
,
1234 r2type
, temv
, temm
);
1240 /* Just track trailing zeros in both operands and transfer
1241 them to the other. */
1242 int r1tz
= (r1val
| r1mask
).trailing_zeros ();
1243 int r2tz
= (r2val
| r2mask
).trailing_zeros ();
1244 if (r1tz
+ r2tz
>= HOST_BITS_PER_DOUBLE_INT
)
1246 *mask
= double_int_zero
;
1247 *val
= double_int_zero
;
1249 else if (r1tz
+ r2tz
> 0)
1251 *mask
= ~double_int::mask (r1tz
+ r2tz
);
1252 *mask
= (*mask
).ext (TYPE_PRECISION (type
), uns
);
1253 *val
= double_int_zero
;
1261 double_int m
= r1mask
| r2mask
;
1262 if (r1val
.and_not (m
) != r2val
.and_not (m
))
1264 *mask
= double_int_zero
;
1265 *val
= ((code
== EQ_EXPR
) ? double_int_zero
: double_int_one
);
1269 /* We know the result of a comparison is always one or zero. */
1270 *mask
= double_int_one
;
1271 *val
= double_int_zero
;
1279 double_int tem
= r1val
;
1285 code
= swap_tree_comparison (code
);
1292 /* If the most significant bits are not known we know nothing. */
1293 if (r1mask
.is_negative () || r2mask
.is_negative ())
1296 /* For comparisons the signedness is in the comparison operands. */
1297 uns
= TYPE_UNSIGNED (r1type
);
1299 /* If we know the most significant bits we know the values
1300 value ranges by means of treating varying bits as zero
1301 or one. Do a cross comparison of the max/min pairs. */
1302 maxmin
= (r1val
| r1mask
).cmp (r2val
.and_not (r2mask
), uns
);
1303 minmax
= r1val
.and_not (r1mask
).cmp (r2val
| r2mask
, uns
);
1304 if (maxmin
< 0) /* r1 is less than r2. */
1306 *mask
= double_int_zero
;
1307 *val
= double_int_one
;
1309 else if (minmax
> 0) /* r1 is not less or equal to r2. */
1311 *mask
= double_int_zero
;
1312 *val
= double_int_zero
;
1314 else if (maxmin
== minmax
) /* r1 and r2 are equal. */
1316 /* This probably should never happen as we'd have
1317 folded the thing during fully constant value folding. */
1318 *mask
= double_int_zero
;
1319 *val
= (code
== LE_EXPR
? double_int_one
: double_int_zero
);
1323 /* We know the result of a comparison is always one or zero. */
1324 *mask
= double_int_one
;
1325 *val
= double_int_zero
;
1334 /* Return the propagation value when applying the operation CODE to
1335 the value RHS yielding type TYPE. */
1338 bit_value_unop (enum tree_code code
, tree type
, tree rhs
)
1340 prop_value_t rval
= get_value_for_expr (rhs
, true);
1341 double_int value
, mask
;
1344 if (rval
.lattice_val
== UNDEFINED
)
1347 gcc_assert ((rval
.lattice_val
== CONSTANT
1348 && TREE_CODE (rval
.value
) == INTEGER_CST
)
1349 || rval
.mask
.is_minus_one ());
1350 bit_value_unop_1 (code
, type
, &value
, &mask
,
1351 TREE_TYPE (rhs
), value_to_double_int (rval
), rval
.mask
);
1352 if (!mask
.is_minus_one ())
1354 val
.lattice_val
= CONSTANT
;
1356 /* ??? Delay building trees here. */
1357 val
.value
= double_int_to_tree (type
, value
);
1361 val
.lattice_val
= VARYING
;
1362 val
.value
= NULL_TREE
;
1363 val
.mask
= double_int_minus_one
;
1368 /* Return the propagation value when applying the operation CODE to
1369 the values RHS1 and RHS2 yielding type TYPE. */
1372 bit_value_binop (enum tree_code code
, tree type
, tree rhs1
, tree rhs2
)
1374 prop_value_t r1val
= get_value_for_expr (rhs1
, true);
1375 prop_value_t r2val
= get_value_for_expr (rhs2
, true);
1376 double_int value
, mask
;
1379 if (r1val
.lattice_val
== UNDEFINED
1380 || r2val
.lattice_val
== UNDEFINED
)
1382 val
.lattice_val
= VARYING
;
1383 val
.value
= NULL_TREE
;
1384 val
.mask
= double_int_minus_one
;
1388 gcc_assert ((r1val
.lattice_val
== CONSTANT
1389 && TREE_CODE (r1val
.value
) == INTEGER_CST
)
1390 || r1val
.mask
.is_minus_one ());
1391 gcc_assert ((r2val
.lattice_val
== CONSTANT
1392 && TREE_CODE (r2val
.value
) == INTEGER_CST
)
1393 || r2val
.mask
.is_minus_one ());
1394 bit_value_binop_1 (code
, type
, &value
, &mask
,
1395 TREE_TYPE (rhs1
), value_to_double_int (r1val
), r1val
.mask
,
1396 TREE_TYPE (rhs2
), value_to_double_int (r2val
), r2val
.mask
);
1397 if (!mask
.is_minus_one ())
1399 val
.lattice_val
= CONSTANT
;
1401 /* ??? Delay building trees here. */
1402 val
.value
= double_int_to_tree (type
, value
);
1406 val
.lattice_val
= VARYING
;
1407 val
.value
= NULL_TREE
;
1408 val
.mask
= double_int_minus_one
;
1413 /* Return the propagation value when applying __builtin_assume_aligned to
1417 bit_value_assume_aligned (gimple stmt
)
1419 tree ptr
= gimple_call_arg (stmt
, 0), align
, misalign
= NULL_TREE
;
1420 tree type
= TREE_TYPE (ptr
);
1421 unsigned HOST_WIDE_INT aligni
, misaligni
= 0;
1422 prop_value_t ptrval
= get_value_for_expr (ptr
, true);
1423 prop_value_t alignval
;
1424 double_int value
, mask
;
1426 if (ptrval
.lattice_val
== UNDEFINED
)
1428 gcc_assert ((ptrval
.lattice_val
== CONSTANT
1429 && TREE_CODE (ptrval
.value
) == INTEGER_CST
)
1430 || ptrval
.mask
.is_minus_one ());
1431 align
= gimple_call_arg (stmt
, 1);
1432 if (!host_integerp (align
, 1))
1434 aligni
= tree_low_cst (align
, 1);
1436 || (aligni
& (aligni
- 1)) != 0)
1438 if (gimple_call_num_args (stmt
) > 2)
1440 misalign
= gimple_call_arg (stmt
, 2);
1441 if (!host_integerp (misalign
, 1))
1443 misaligni
= tree_low_cst (misalign
, 1);
1444 if (misaligni
>= aligni
)
1447 align
= build_int_cst_type (type
, -aligni
);
1448 alignval
= get_value_for_expr (align
, true);
1449 bit_value_binop_1 (BIT_AND_EXPR
, type
, &value
, &mask
,
1450 type
, value_to_double_int (ptrval
), ptrval
.mask
,
1451 type
, value_to_double_int (alignval
), alignval
.mask
);
1452 if (!mask
.is_minus_one ())
1454 val
.lattice_val
= CONSTANT
;
1456 gcc_assert ((mask
.low
& (aligni
- 1)) == 0);
1457 gcc_assert ((value
.low
& (aligni
- 1)) == 0);
1458 value
.low
|= misaligni
;
1459 /* ??? Delay building trees here. */
1460 val
.value
= double_int_to_tree (type
, value
);
1464 val
.lattice_val
= VARYING
;
1465 val
.value
= NULL_TREE
;
1466 val
.mask
= double_int_minus_one
;
1471 /* Evaluate statement STMT.
1472 Valid only for assignments, calls, conditionals, and switches. */
1475 evaluate_stmt (gimple stmt
)
1478 tree simplified
= NULL_TREE
;
1479 ccp_lattice_t likelyvalue
= likely_value (stmt
);
1480 bool is_constant
= false;
1483 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1485 fprintf (dump_file
, "which is likely ");
1486 switch (likelyvalue
)
1489 fprintf (dump_file
, "CONSTANT");
1492 fprintf (dump_file
, "UNDEFINED");
1495 fprintf (dump_file
, "VARYING");
1499 fprintf (dump_file
, "\n");
1502 /* If the statement is likely to have a CONSTANT result, then try
1503 to fold the statement to determine the constant value. */
1504 /* FIXME. This is the only place that we call ccp_fold.
1505 Since likely_value never returns CONSTANT for calls, we will
1506 not attempt to fold them, including builtins that may profit. */
1507 if (likelyvalue
== CONSTANT
)
1509 fold_defer_overflow_warnings ();
1510 simplified
= ccp_fold (stmt
);
1511 is_constant
= simplified
&& is_gimple_min_invariant (simplified
);
1512 fold_undefer_overflow_warnings (is_constant
, stmt
, 0);
1515 /* The statement produced a constant value. */
1516 val
.lattice_val
= CONSTANT
;
1517 val
.value
= simplified
;
1518 val
.mask
= double_int_zero
;
1521 /* If the statement is likely to have a VARYING result, then do not
1522 bother folding the statement. */
1523 else if (likelyvalue
== VARYING
)
1525 enum gimple_code code
= gimple_code (stmt
);
1526 if (code
== GIMPLE_ASSIGN
)
1528 enum tree_code subcode
= gimple_assign_rhs_code (stmt
);
1530 /* Other cases cannot satisfy is_gimple_min_invariant
1532 if (get_gimple_rhs_class (subcode
) == GIMPLE_SINGLE_RHS
)
1533 simplified
= gimple_assign_rhs1 (stmt
);
1535 else if (code
== GIMPLE_SWITCH
)
1536 simplified
= gimple_switch_index (stmt
);
1538 /* These cannot satisfy is_gimple_min_invariant without folding. */
1539 gcc_assert (code
== GIMPLE_CALL
|| code
== GIMPLE_COND
);
1540 is_constant
= simplified
&& is_gimple_min_invariant (simplified
);
1543 /* The statement produced a constant value. */
1544 val
.lattice_val
= CONSTANT
;
1545 val
.value
= simplified
;
1546 val
.mask
= double_int_zero
;
1550 /* Resort to simplification for bitwise tracking. */
1551 if (flag_tree_bit_ccp
1552 && (likelyvalue
== CONSTANT
|| is_gimple_call (stmt
))
1555 enum gimple_code code
= gimple_code (stmt
);
1556 val
.lattice_val
= VARYING
;
1557 val
.value
= NULL_TREE
;
1558 val
.mask
= double_int_minus_one
;
1559 if (code
== GIMPLE_ASSIGN
)
1561 enum tree_code subcode
= gimple_assign_rhs_code (stmt
);
1562 tree rhs1
= gimple_assign_rhs1 (stmt
);
1563 switch (get_gimple_rhs_class (subcode
))
1565 case GIMPLE_SINGLE_RHS
:
1566 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1567 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1568 val
= get_value_for_expr (rhs1
, true);
1571 case GIMPLE_UNARY_RHS
:
1572 if ((INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1573 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1574 && (INTEGRAL_TYPE_P (gimple_expr_type (stmt
))
1575 || POINTER_TYPE_P (gimple_expr_type (stmt
))))
1576 val
= bit_value_unop (subcode
, gimple_expr_type (stmt
), rhs1
);
1579 case GIMPLE_BINARY_RHS
:
1580 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1581 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1583 tree lhs
= gimple_assign_lhs (stmt
);
1584 tree rhs2
= gimple_assign_rhs2 (stmt
);
1585 val
= bit_value_binop (subcode
,
1586 TREE_TYPE (lhs
), rhs1
, rhs2
);
1593 else if (code
== GIMPLE_COND
)
1595 enum tree_code code
= gimple_cond_code (stmt
);
1596 tree rhs1
= gimple_cond_lhs (stmt
);
1597 tree rhs2
= gimple_cond_rhs (stmt
);
1598 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1599 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1600 val
= bit_value_binop (code
, TREE_TYPE (rhs1
), rhs1
, rhs2
);
1602 else if (gimple_call_builtin_p (stmt
, BUILT_IN_NORMAL
))
1604 tree fndecl
= gimple_call_fndecl (stmt
);
1605 switch (DECL_FUNCTION_CODE (fndecl
))
1607 case BUILT_IN_MALLOC
:
1608 case BUILT_IN_REALLOC
:
1609 case BUILT_IN_CALLOC
:
1610 case BUILT_IN_STRDUP
:
1611 case BUILT_IN_STRNDUP
:
1612 val
.lattice_val
= CONSTANT
;
1613 val
.value
= build_int_cst (TREE_TYPE (gimple_get_lhs (stmt
)), 0);
1614 val
.mask
= double_int::from_shwi
1615 (~(((HOST_WIDE_INT
) MALLOC_ABI_ALIGNMENT
)
1616 / BITS_PER_UNIT
- 1));
1619 case BUILT_IN_ALLOCA
:
1620 case BUILT_IN_ALLOCA_WITH_ALIGN
:
1621 align
= (DECL_FUNCTION_CODE (fndecl
) == BUILT_IN_ALLOCA_WITH_ALIGN
1622 ? TREE_INT_CST_LOW (gimple_call_arg (stmt
, 1))
1623 : BIGGEST_ALIGNMENT
);
1624 val
.lattice_val
= CONSTANT
;
1625 val
.value
= build_int_cst (TREE_TYPE (gimple_get_lhs (stmt
)), 0);
1626 val
.mask
= double_int::from_shwi (~(((HOST_WIDE_INT
) align
)
1627 / BITS_PER_UNIT
- 1));
1630 /* These builtins return their first argument, unmodified. */
1631 case BUILT_IN_MEMCPY
:
1632 case BUILT_IN_MEMMOVE
:
1633 case BUILT_IN_MEMSET
:
1634 case BUILT_IN_STRCPY
:
1635 case BUILT_IN_STRNCPY
:
1636 case BUILT_IN_MEMCPY_CHK
:
1637 case BUILT_IN_MEMMOVE_CHK
:
1638 case BUILT_IN_MEMSET_CHK
:
1639 case BUILT_IN_STRCPY_CHK
:
1640 case BUILT_IN_STRNCPY_CHK
:
1641 val
= get_value_for_expr (gimple_call_arg (stmt
, 0), true);
1644 case BUILT_IN_ASSUME_ALIGNED
:
1645 val
= bit_value_assume_aligned (stmt
);
1651 is_constant
= (val
.lattice_val
== CONSTANT
);
1656 /* The statement produced a nonconstant value. If the statement
1657 had UNDEFINED operands, then the result of the statement
1658 should be UNDEFINED. Otherwise, the statement is VARYING. */
1659 if (likelyvalue
== UNDEFINED
)
1661 val
.lattice_val
= likelyvalue
;
1662 val
.mask
= double_int_zero
;
1666 val
.lattice_val
= VARYING
;
1667 val
.mask
= double_int_minus_one
;
1670 val
.value
= NULL_TREE
;
1676 typedef hash_table
<pointer_hash
<gimple_statement_d
> > gimple_htab
;
1678 /* Given a BUILT_IN_STACK_SAVE value SAVED_VAL, insert a clobber of VAR before
1679 each matching BUILT_IN_STACK_RESTORE. Mark visited phis in VISITED. */
1682 insert_clobber_before_stack_restore (tree saved_val
, tree var
,
1683 gimple_htab
*visited
)
1685 gimple stmt
, clobber_stmt
;
1687 imm_use_iterator iter
;
1688 gimple_stmt_iterator i
;
1691 FOR_EACH_IMM_USE_STMT (stmt
, iter
, saved_val
)
1692 if (gimple_call_builtin_p (stmt
, BUILT_IN_STACK_RESTORE
))
1694 clobber
= build_constructor (TREE_TYPE (var
),
1696 TREE_THIS_VOLATILE (clobber
) = 1;
1697 clobber_stmt
= gimple_build_assign (var
, clobber
);
1699 i
= gsi_for_stmt (stmt
);
1700 gsi_insert_before (&i
, clobber_stmt
, GSI_SAME_STMT
);
1702 else if (gimple_code (stmt
) == GIMPLE_PHI
)
1704 if (!visited
->is_created ())
1705 visited
->create (10);
1707 slot
= visited
->find_slot (stmt
, INSERT
);
1712 insert_clobber_before_stack_restore (gimple_phi_result (stmt
), var
,
1716 gcc_assert (is_gimple_debug (stmt
));
1719 /* Advance the iterator to the previous non-debug gimple statement in the same
1720 or dominating basic block. */
1723 gsi_prev_dom_bb_nondebug (gimple_stmt_iterator
*i
)
1727 gsi_prev_nondebug (i
);
1728 while (gsi_end_p (*i
))
1730 dom
= get_immediate_dominator (CDI_DOMINATORS
, i
->bb
);
1731 if (dom
== NULL
|| dom
== ENTRY_BLOCK_PTR
)
1734 *i
= gsi_last_bb (dom
);
1738 /* Find a BUILT_IN_STACK_SAVE dominating gsi_stmt (I), and insert
1739 a clobber of VAR before each matching BUILT_IN_STACK_RESTORE.
1741 It is possible that BUILT_IN_STACK_SAVE cannot be find in a dominator when a
1742 previous pass (such as DOM) duplicated it along multiple paths to a BB. In
1743 that case the function gives up without inserting the clobbers. */
1746 insert_clobbers_for_var (gimple_stmt_iterator i
, tree var
)
1750 gimple_htab visited
;
1752 for (; !gsi_end_p (i
); gsi_prev_dom_bb_nondebug (&i
))
1754 stmt
= gsi_stmt (i
);
1756 if (!gimple_call_builtin_p (stmt
, BUILT_IN_STACK_SAVE
))
1759 saved_val
= gimple_call_lhs (stmt
);
1760 if (saved_val
== NULL_TREE
)
1763 insert_clobber_before_stack_restore (saved_val
, var
, &visited
);
1767 if (visited
.is_created ())
1771 /* Detects a __builtin_alloca_with_align with constant size argument. Declares
1772 fixed-size array and returns the address, if found, otherwise returns
1776 fold_builtin_alloca_with_align (gimple stmt
)
1778 unsigned HOST_WIDE_INT size
, threshold
, n_elem
;
1779 tree lhs
, arg
, block
, var
, elem_type
, array_type
;
1782 lhs
= gimple_call_lhs (stmt
);
1783 if (lhs
== NULL_TREE
)
1786 /* Detect constant argument. */
1787 arg
= get_constant_value (gimple_call_arg (stmt
, 0));
1788 if (arg
== NULL_TREE
1789 || TREE_CODE (arg
) != INTEGER_CST
1790 || !host_integerp (arg
, 1))
1793 size
= TREE_INT_CST_LOW (arg
);
1795 /* Heuristic: don't fold large allocas. */
1796 threshold
= (unsigned HOST_WIDE_INT
)PARAM_VALUE (PARAM_LARGE_STACK_FRAME
);
1797 /* In case the alloca is located at function entry, it has the same lifetime
1798 as a declared array, so we allow a larger size. */
1799 block
= gimple_block (stmt
);
1800 if (!(cfun
->after_inlining
1801 && TREE_CODE (BLOCK_SUPERCONTEXT (block
)) == FUNCTION_DECL
))
1803 if (size
> threshold
)
1806 /* Declare array. */
1807 elem_type
= build_nonstandard_integer_type (BITS_PER_UNIT
, 1);
1808 n_elem
= size
* 8 / BITS_PER_UNIT
;
1809 array_type
= build_array_type_nelts (elem_type
, n_elem
);
1810 var
= create_tmp_var (array_type
, NULL
);
1811 DECL_ALIGN (var
) = TREE_INT_CST_LOW (gimple_call_arg (stmt
, 1));
1813 struct ptr_info_def
*pi
= SSA_NAME_PTR_INFO (lhs
);
1814 if (pi
!= NULL
&& !pi
->pt
.anything
)
1818 singleton_p
= pt_solution_singleton_p (&pi
->pt
, &uid
);
1819 gcc_assert (singleton_p
);
1820 SET_DECL_PT_UID (var
, uid
);
1824 /* Fold alloca to the address of the array. */
1825 return fold_convert (TREE_TYPE (lhs
), build_fold_addr_expr (var
));
1828 /* Fold the stmt at *GSI with CCP specific information that propagating
1829 and regular folding does not catch. */
1832 ccp_fold_stmt (gimple_stmt_iterator
*gsi
)
1834 gimple stmt
= gsi_stmt (*gsi
);
1836 switch (gimple_code (stmt
))
1841 /* Statement evaluation will handle type mismatches in constants
1842 more gracefully than the final propagation. This allows us to
1843 fold more conditionals here. */
1844 val
= evaluate_stmt (stmt
);
1845 if (val
.lattice_val
!= CONSTANT
1846 || !val
.mask
.is_zero ())
1851 fprintf (dump_file
, "Folding predicate ");
1852 print_gimple_expr (dump_file
, stmt
, 0, 0);
1853 fprintf (dump_file
, " to ");
1854 print_generic_expr (dump_file
, val
.value
, 0);
1855 fprintf (dump_file
, "\n");
1858 if (integer_zerop (val
.value
))
1859 gimple_cond_make_false (stmt
);
1861 gimple_cond_make_true (stmt
);
1868 tree lhs
= gimple_call_lhs (stmt
);
1869 int flags
= gimple_call_flags (stmt
);
1872 bool changed
= false;
1875 /* If the call was folded into a constant make sure it goes
1876 away even if we cannot propagate into all uses because of
1879 && TREE_CODE (lhs
) == SSA_NAME
1880 && (val
= get_constant_value (lhs
))
1881 /* Don't optimize away calls that have side-effects. */
1882 && (flags
& (ECF_CONST
|ECF_PURE
)) != 0
1883 && (flags
& ECF_LOOPING_CONST_OR_PURE
) == 0)
1885 tree new_rhs
= unshare_expr (val
);
1887 if (!useless_type_conversion_p (TREE_TYPE (lhs
),
1888 TREE_TYPE (new_rhs
)))
1889 new_rhs
= fold_convert (TREE_TYPE (lhs
), new_rhs
);
1890 res
= update_call_from_tree (gsi
, new_rhs
);
1895 /* Internal calls provide no argument types, so the extra laxity
1896 for normal calls does not apply. */
1897 if (gimple_call_internal_p (stmt
))
1900 /* The heuristic of fold_builtin_alloca_with_align differs before and
1901 after inlining, so we don't require the arg to be changed into a
1902 constant for folding, but just to be constant. */
1903 if (gimple_call_builtin_p (stmt
, BUILT_IN_ALLOCA_WITH_ALIGN
))
1905 tree new_rhs
= fold_builtin_alloca_with_align (stmt
);
1908 bool res
= update_call_from_tree (gsi
, new_rhs
);
1909 tree var
= TREE_OPERAND (TREE_OPERAND (new_rhs
, 0),0);
1911 insert_clobbers_for_var (*gsi
, var
);
1916 /* Propagate into the call arguments. Compared to replace_uses_in
1917 this can use the argument slot types for type verification
1918 instead of the current argument type. We also can safely
1919 drop qualifiers here as we are dealing with constants anyway. */
1920 argt
= TYPE_ARG_TYPES (gimple_call_fntype (stmt
));
1921 for (i
= 0; i
< gimple_call_num_args (stmt
) && argt
;
1922 ++i
, argt
= TREE_CHAIN (argt
))
1924 tree arg
= gimple_call_arg (stmt
, i
);
1925 if (TREE_CODE (arg
) == SSA_NAME
1926 && (val
= get_constant_value (arg
))
1927 && useless_type_conversion_p
1928 (TYPE_MAIN_VARIANT (TREE_VALUE (argt
)),
1929 TYPE_MAIN_VARIANT (TREE_TYPE (val
))))
1931 gimple_call_set_arg (stmt
, i
, unshare_expr (val
));
1941 tree lhs
= gimple_assign_lhs (stmt
);
1944 /* If we have a load that turned out to be constant replace it
1945 as we cannot propagate into all uses in all cases. */
1946 if (gimple_assign_single_p (stmt
)
1947 && TREE_CODE (lhs
) == SSA_NAME
1948 && (val
= get_constant_value (lhs
)))
1950 tree rhs
= unshare_expr (val
);
1951 if (!useless_type_conversion_p (TREE_TYPE (lhs
), TREE_TYPE (rhs
)))
1952 rhs
= fold_build1 (VIEW_CONVERT_EXPR
, TREE_TYPE (lhs
), rhs
);
1953 gimple_assign_set_rhs_from_tree (gsi
, rhs
);
1965 /* Visit the assignment statement STMT. Set the value of its LHS to the
1966 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
1967 creates virtual definitions, set the value of each new name to that
1968 of the RHS (if we can derive a constant out of the RHS).
1969 Value-returning call statements also perform an assignment, and
1970 are handled here. */
1972 static enum ssa_prop_result
1973 visit_assignment (gimple stmt
, tree
*output_p
)
1976 enum ssa_prop_result retval
;
1978 tree lhs
= gimple_get_lhs (stmt
);
1980 gcc_assert (gimple_code (stmt
) != GIMPLE_CALL
1981 || gimple_call_lhs (stmt
) != NULL_TREE
);
1983 if (gimple_assign_single_p (stmt
)
1984 && gimple_assign_rhs_code (stmt
) == SSA_NAME
)
1985 /* For a simple copy operation, we copy the lattice values. */
1986 val
= *get_value (gimple_assign_rhs1 (stmt
));
1988 /* Evaluate the statement, which could be
1989 either a GIMPLE_ASSIGN or a GIMPLE_CALL. */
1990 val
= evaluate_stmt (stmt
);
1992 retval
= SSA_PROP_NOT_INTERESTING
;
1994 /* Set the lattice value of the statement's output. */
1995 if (TREE_CODE (lhs
) == SSA_NAME
)
1997 /* If STMT is an assignment to an SSA_NAME, we only have one
1999 if (set_lattice_value (lhs
, val
))
2002 if (val
.lattice_val
== VARYING
)
2003 retval
= SSA_PROP_VARYING
;
2005 retval
= SSA_PROP_INTERESTING
;
2013 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
2014 if it can determine which edge will be taken. Otherwise, return
2015 SSA_PROP_VARYING. */
2017 static enum ssa_prop_result
2018 visit_cond_stmt (gimple stmt
, edge
*taken_edge_p
)
2023 block
= gimple_bb (stmt
);
2024 val
= evaluate_stmt (stmt
);
2025 if (val
.lattice_val
!= CONSTANT
2026 || !val
.mask
.is_zero ())
2027 return SSA_PROP_VARYING
;
2029 /* Find which edge out of the conditional block will be taken and add it
2030 to the worklist. If no single edge can be determined statically,
2031 return SSA_PROP_VARYING to feed all the outgoing edges to the
2032 propagation engine. */
2033 *taken_edge_p
= find_taken_edge (block
, val
.value
);
2035 return SSA_PROP_INTERESTING
;
2037 return SSA_PROP_VARYING
;
2041 /* Evaluate statement STMT. If the statement produces an output value and
2042 its evaluation changes the lattice value of its output, return
2043 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
2046 If STMT is a conditional branch and we can determine its truth
2047 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
2048 value, return SSA_PROP_VARYING. */
2050 static enum ssa_prop_result
2051 ccp_visit_stmt (gimple stmt
, edge
*taken_edge_p
, tree
*output_p
)
2056 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2058 fprintf (dump_file
, "\nVisiting statement:\n");
2059 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2062 switch (gimple_code (stmt
))
2065 /* If the statement is an assignment that produces a single
2066 output value, evaluate its RHS to see if the lattice value of
2067 its output has changed. */
2068 return visit_assignment (stmt
, output_p
);
2071 /* A value-returning call also performs an assignment. */
2072 if (gimple_call_lhs (stmt
) != NULL_TREE
)
2073 return visit_assignment (stmt
, output_p
);
2078 /* If STMT is a conditional branch, see if we can determine
2079 which branch will be taken. */
2080 /* FIXME. It appears that we should be able to optimize
2081 computed GOTOs here as well. */
2082 return visit_cond_stmt (stmt
, taken_edge_p
);
2088 /* Any other kind of statement is not interesting for constant
2089 propagation and, therefore, not worth simulating. */
2090 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2091 fprintf (dump_file
, "No interesting values produced. Marked VARYING.\n");
2093 /* Definitions made by statements other than assignments to
2094 SSA_NAMEs represent unknown modifications to their outputs.
2095 Mark them VARYING. */
2096 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
2098 prop_value_t v
= { VARYING
, NULL_TREE
, { -1, (HOST_WIDE_INT
) -1 } };
2099 set_lattice_value (def
, v
);
2102 return SSA_PROP_VARYING
;
2106 /* Main entry point for SSA Conditional Constant Propagation. */
2111 unsigned int todo
= 0;
2112 calculate_dominance_info (CDI_DOMINATORS
);
2114 ssa_propagate (ccp_visit_stmt
, ccp_visit_phi_node
);
2115 if (ccp_finalize ())
2116 todo
= (TODO_cleanup_cfg
| TODO_update_ssa
);
2117 free_dominance_info (CDI_DOMINATORS
);
2125 return flag_tree_ccp
!= 0;
2131 const pass_data pass_data_ccp
=
2133 GIMPLE_PASS
, /* type */
2135 OPTGROUP_NONE
, /* optinfo_flags */
2136 true, /* has_gate */
2137 true, /* has_execute */
2138 TV_TREE_CCP
, /* tv_id */
2139 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2140 0, /* properties_provided */
2141 0, /* properties_destroyed */
2142 0, /* todo_flags_start */
2143 ( TODO_verify_ssa
| TODO_update_address_taken
2144 | TODO_verify_stmts
), /* todo_flags_finish */
2147 class pass_ccp
: public gimple_opt_pass
2150 pass_ccp(gcc::context
*ctxt
)
2151 : gimple_opt_pass(pass_data_ccp
, ctxt
)
2154 /* opt_pass methods: */
2155 opt_pass
* clone () { return new pass_ccp (ctxt_
); }
2156 bool gate () { return gate_ccp (); }
2157 unsigned int execute () { return do_ssa_ccp (); }
2159 }; // class pass_ccp
2164 make_pass_ccp (gcc::context
*ctxt
)
2166 return new pass_ccp (ctxt
);
2171 /* Try to optimize out __builtin_stack_restore. Optimize it out
2172 if there is another __builtin_stack_restore in the same basic
2173 block and no calls or ASM_EXPRs are in between, or if this block's
2174 only outgoing edge is to EXIT_BLOCK and there are no calls or
2175 ASM_EXPRs after this __builtin_stack_restore. */
2178 optimize_stack_restore (gimple_stmt_iterator i
)
2183 basic_block bb
= gsi_bb (i
);
2184 gimple call
= gsi_stmt (i
);
2186 if (gimple_code (call
) != GIMPLE_CALL
2187 || gimple_call_num_args (call
) != 1
2188 || TREE_CODE (gimple_call_arg (call
, 0)) != SSA_NAME
2189 || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call
, 0))))
2192 for (gsi_next (&i
); !gsi_end_p (i
); gsi_next (&i
))
2194 stmt
= gsi_stmt (i
);
2195 if (gimple_code (stmt
) == GIMPLE_ASM
)
2197 if (gimple_code (stmt
) != GIMPLE_CALL
)
2200 callee
= gimple_call_fndecl (stmt
);
2202 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2203 /* All regular builtins are ok, just obviously not alloca. */
2204 || DECL_FUNCTION_CODE (callee
) == BUILT_IN_ALLOCA
2205 || DECL_FUNCTION_CODE (callee
) == BUILT_IN_ALLOCA_WITH_ALIGN
)
2208 if (DECL_FUNCTION_CODE (callee
) == BUILT_IN_STACK_RESTORE
)
2209 goto second_stack_restore
;
2215 /* Allow one successor of the exit block, or zero successors. */
2216 switch (EDGE_COUNT (bb
->succs
))
2221 if (single_succ_edge (bb
)->dest
!= EXIT_BLOCK_PTR
)
2227 second_stack_restore
:
2229 /* If there's exactly one use, then zap the call to __builtin_stack_save.
2230 If there are multiple uses, then the last one should remove the call.
2231 In any case, whether the call to __builtin_stack_save can be removed
2232 or not is irrelevant to removing the call to __builtin_stack_restore. */
2233 if (has_single_use (gimple_call_arg (call
, 0)))
2235 gimple stack_save
= SSA_NAME_DEF_STMT (gimple_call_arg (call
, 0));
2236 if (is_gimple_call (stack_save
))
2238 callee
= gimple_call_fndecl (stack_save
);
2240 && DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
2241 && DECL_FUNCTION_CODE (callee
) == BUILT_IN_STACK_SAVE
)
2243 gimple_stmt_iterator stack_save_gsi
;
2246 stack_save_gsi
= gsi_for_stmt (stack_save
);
2247 rhs
= build_int_cst (TREE_TYPE (gimple_call_arg (call
, 0)), 0);
2248 update_call_from_tree (&stack_save_gsi
, rhs
);
2253 /* No effect, so the statement will be deleted. */
2254 return integer_zero_node
;
2257 /* If va_list type is a simple pointer and nothing special is needed,
2258 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
2259 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
2260 pointer assignment. */
2263 optimize_stdarg_builtin (gimple call
)
2265 tree callee
, lhs
, rhs
, cfun_va_list
;
2266 bool va_list_simple_ptr
;
2267 location_t loc
= gimple_location (call
);
2269 if (gimple_code (call
) != GIMPLE_CALL
)
2272 callee
= gimple_call_fndecl (call
);
2274 cfun_va_list
= targetm
.fn_abi_va_list (callee
);
2275 va_list_simple_ptr
= POINTER_TYPE_P (cfun_va_list
)
2276 && (TREE_TYPE (cfun_va_list
) == void_type_node
2277 || TREE_TYPE (cfun_va_list
) == char_type_node
);
2279 switch (DECL_FUNCTION_CODE (callee
))
2281 case BUILT_IN_VA_START
:
2282 if (!va_list_simple_ptr
2283 || targetm
.expand_builtin_va_start
!= NULL
2284 || !builtin_decl_explicit_p (BUILT_IN_NEXT_ARG
))
2287 if (gimple_call_num_args (call
) != 2)
2290 lhs
= gimple_call_arg (call
, 0);
2291 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2292 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2293 != TYPE_MAIN_VARIANT (cfun_va_list
))
2296 lhs
= build_fold_indirect_ref_loc (loc
, lhs
);
2297 rhs
= build_call_expr_loc (loc
, builtin_decl_explicit (BUILT_IN_NEXT_ARG
),
2298 1, integer_zero_node
);
2299 rhs
= fold_convert_loc (loc
, TREE_TYPE (lhs
), rhs
);
2300 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2302 case BUILT_IN_VA_COPY
:
2303 if (!va_list_simple_ptr
)
2306 if (gimple_call_num_args (call
) != 2)
2309 lhs
= gimple_call_arg (call
, 0);
2310 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2311 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2312 != TYPE_MAIN_VARIANT (cfun_va_list
))
2315 lhs
= build_fold_indirect_ref_loc (loc
, lhs
);
2316 rhs
= gimple_call_arg (call
, 1);
2317 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs
))
2318 != TYPE_MAIN_VARIANT (cfun_va_list
))
2321 rhs
= fold_convert_loc (loc
, TREE_TYPE (lhs
), rhs
);
2322 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2324 case BUILT_IN_VA_END
:
2325 /* No effect, so the statement will be deleted. */
2326 return integer_zero_node
;
2333 /* Attemp to make the block of __builtin_unreachable I unreachable by changing
2334 the incoming jumps. Return true if at least one jump was changed. */
2337 optimize_unreachable (gimple_stmt_iterator i
)
2339 basic_block bb
= gsi_bb (i
);
2340 gimple_stmt_iterator gsi
;
2346 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
2348 stmt
= gsi_stmt (gsi
);
2350 if (is_gimple_debug (stmt
))
2353 if (gimple_code (stmt
) == GIMPLE_LABEL
)
2355 /* Verify we do not need to preserve the label. */
2356 if (FORCED_LABEL (gimple_label_label (stmt
)))
2362 /* Only handle the case that __builtin_unreachable is the first statement
2363 in the block. We rely on DCE to remove stmts without side-effects
2364 before __builtin_unreachable. */
2365 if (gsi_stmt (gsi
) != gsi_stmt (i
))
2370 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
2372 gsi
= gsi_last_bb (e
->src
);
2373 if (gsi_end_p (gsi
))
2376 stmt
= gsi_stmt (gsi
);
2377 if (gimple_code (stmt
) == GIMPLE_COND
)
2379 if (e
->flags
& EDGE_TRUE_VALUE
)
2380 gimple_cond_make_false (stmt
);
2381 else if (e
->flags
& EDGE_FALSE_VALUE
)
2382 gimple_cond_make_true (stmt
);
2389 /* Todo: handle other cases, f.i. switch statement. */
2399 /* A simple pass that attempts to fold all builtin functions. This pass
2400 is run after we've propagated as many constants as we can. */
2403 execute_fold_all_builtins (void)
2405 bool cfg_changed
= false;
2407 unsigned int todoflags
= 0;
2411 gimple_stmt_iterator i
;
2412 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); )
2414 gimple stmt
, old_stmt
;
2415 tree callee
, result
;
2416 enum built_in_function fcode
;
2418 stmt
= gsi_stmt (i
);
2420 if (gimple_code (stmt
) != GIMPLE_CALL
)
2422 /* Remove all *ssaname_N ={v} {CLOBBER}; stmts,
2423 after the last GIMPLE DSE they aren't needed and might
2424 unnecessarily keep the SSA_NAMEs live. */
2425 if (gimple_clobber_p (stmt
))
2427 tree lhs
= gimple_assign_lhs (stmt
);
2428 if (TREE_CODE (lhs
) == MEM_REF
2429 && TREE_CODE (TREE_OPERAND (lhs
, 0)) == SSA_NAME
)
2431 unlink_stmt_vdef (stmt
);
2432 gsi_remove (&i
, true);
2433 release_defs (stmt
);
2440 callee
= gimple_call_fndecl (stmt
);
2441 if (!callee
|| DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
)
2446 fcode
= DECL_FUNCTION_CODE (callee
);
2448 result
= gimple_fold_builtin (stmt
);
2451 gimple_remove_stmt_histograms (cfun
, stmt
);
2454 switch (DECL_FUNCTION_CODE (callee
))
2456 case BUILT_IN_CONSTANT_P
:
2457 /* Resolve __builtin_constant_p. If it hasn't been
2458 folded to integer_one_node by now, it's fairly
2459 certain that the value simply isn't constant. */
2460 result
= integer_zero_node
;
2463 case BUILT_IN_ASSUME_ALIGNED
:
2464 /* Remove __builtin_assume_aligned. */
2465 result
= gimple_call_arg (stmt
, 0);
2468 case BUILT_IN_STACK_RESTORE
:
2469 result
= optimize_stack_restore (i
);
2475 case BUILT_IN_UNREACHABLE
:
2476 if (optimize_unreachable (i
))
2480 case BUILT_IN_VA_START
:
2481 case BUILT_IN_VA_END
:
2482 case BUILT_IN_VA_COPY
:
2483 /* These shouldn't be folded before pass_stdarg. */
2484 result
= optimize_stdarg_builtin (stmt
);
2494 if (result
== NULL_TREE
)
2497 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2499 fprintf (dump_file
, "Simplified\n ");
2500 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2504 if (!update_call_from_tree (&i
, result
))
2506 gimplify_and_update_call_from_tree (&i
, result
);
2507 todoflags
|= TODO_update_address_taken
;
2510 stmt
= gsi_stmt (i
);
2513 if (maybe_clean_or_replace_eh_stmt (old_stmt
, stmt
)
2514 && gimple_purge_dead_eh_edges (bb
))
2517 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2519 fprintf (dump_file
, "to\n ");
2520 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2521 fprintf (dump_file
, "\n");
2524 /* Retry the same statement if it changed into another
2525 builtin, there might be new opportunities now. */
2526 if (gimple_code (stmt
) != GIMPLE_CALL
)
2531 callee
= gimple_call_fndecl (stmt
);
2533 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2534 || DECL_FUNCTION_CODE (callee
) == fcode
)
2539 /* Delete unreachable blocks. */
2541 todoflags
|= TODO_cleanup_cfg
;
2549 const pass_data pass_data_fold_builtins
=
2551 GIMPLE_PASS
, /* type */
2553 OPTGROUP_NONE
, /* optinfo_flags */
2554 false, /* has_gate */
2555 true, /* has_execute */
2556 TV_NONE
, /* tv_id */
2557 ( PROP_cfg
| PROP_ssa
), /* properties_required */
2558 0, /* properties_provided */
2559 0, /* properties_destroyed */
2560 0, /* todo_flags_start */
2561 ( TODO_verify_ssa
| TODO_update_ssa
), /* todo_flags_finish */
2564 class pass_fold_builtins
: public gimple_opt_pass
2567 pass_fold_builtins(gcc::context
*ctxt
)
2568 : gimple_opt_pass(pass_data_fold_builtins
, ctxt
)
2571 /* opt_pass methods: */
2572 opt_pass
* clone () { return new pass_fold_builtins (ctxt_
); }
2573 unsigned int execute () { return execute_fold_all_builtins (); }
2575 }; // class pass_fold_builtins
2580 make_pass_fold_builtins (gcc::context
*ctxt
)
2582 return new pass_fold_builtins (ctxt
);