1 /* Conditional constant propagation pass for the GNU compiler.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005
3 Free Software Foundation, Inc.
4 Adapted from original RTL SSA-CCP by Daniel Berlin <dberlin@dberlin.org>
5 Adapted to GIMPLE trees by Diego Novillo <dnovillo@redhat.com>
7 This file is part of GCC.
9 GCC is free software; you can redistribute it and/or modify it
10 under the terms of the GNU General Public License as published by the
11 Free Software Foundation; either version 2, or (at your option) any
14 GCC is distributed in the hope that it will be useful, but WITHOUT
15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
16 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
19 You should have received a copy of the GNU General Public License
20 along with GCC; see the file COPYING. If not, write to the Free
21 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
24 /* Conditional constant propagation (CCP) is based on the SSA
25 propagation engine (tree-ssa-propagate.c). Constant assignments of
26 the form VAR = CST are propagated from the assignments into uses of
27 VAR, which in turn may generate new constants. The simulation uses
28 a four level lattice to keep track of constant values associated
29 with SSA names. Given an SSA name V_i, it may take one of the
32 UNINITIALIZED -> This is the default starting value. V_i
33 has not been processed yet.
35 UNDEFINED -> V_i is a local variable whose definition
36 has not been processed yet. Therefore we
37 don't yet know if its value is a constant
40 CONSTANT -> V_i has been found to hold a constant
43 VARYING -> V_i cannot take a constant value, or if it
44 does, it is not possible to determine it
47 The core of SSA-CCP is in ccp_visit_stmt and ccp_visit_phi_node:
49 1- In ccp_visit_stmt, we are interested in assignments whose RHS
50 evaluates into a constant and conditional jumps whose predicate
51 evaluates into a boolean true or false. When an assignment of
52 the form V_i = CONST is found, V_i's lattice value is set to
53 CONSTANT and CONST is associated with it. This causes the
54 propagation engine to add all the SSA edges coming out the
55 assignment into the worklists, so that statements that use V_i
58 If the statement is a conditional with a constant predicate, we
59 mark the outgoing edges as executable or not executable
60 depending on the predicate's value. This is then used when
61 visiting PHI nodes to know when a PHI argument can be ignored.
64 2- In ccp_visit_phi_node, if all the PHI arguments evaluate to the
65 same constant C, then the LHS of the PHI is set to C. This
66 evaluation is known as the "meet operation". Since one of the
67 goals of this evaluation is to optimistically return constant
68 values as often as possible, it uses two main short cuts:
70 - If an argument is flowing in through a non-executable edge, it
71 is ignored. This is useful in cases like this:
77 a_11 = PHI (a_9, a_10)
79 If PRED is known to always evaluate to false, then we can
80 assume that a_11 will always take its value from a_10, meaning
81 that instead of consider it VARYING (a_9 and a_10 have
82 different values), we can consider it CONSTANT 100.
84 - If an argument has an UNDEFINED value, then it does not affect
85 the outcome of the meet operation. If a variable V_i has an
86 UNDEFINED value, it means that either its defining statement
87 hasn't been visited yet or V_i has no defining statement, in
88 which case the original symbol 'V' is being used
89 uninitialized. Since 'V' is a local variable, the compiler
90 may assume any initial value for it.
93 After propagation, every variable V_i that ends up with a lattice
94 value of CONSTANT will have the associated constant value in the
95 array CONST_VAL[i].VALUE. That is fed into substitute_and_fold for
96 final substitution and folding.
99 Constant propagation in stores and loads (STORE-CCP)
100 ----------------------------------------------------
102 While CCP has all the logic to propagate constants in GIMPLE
103 registers, it is missing the ability to associate constants with
104 stores and loads (i.e., pointer dereferences, structures and
105 global/aliased variables). We don't keep loads and stores in
106 SSA, but we do build a factored use-def web for them (in the
109 For instance, consider the following code fragment:
128 We should be able to deduce that the predicate 'a.a != B' is always
129 false. To achieve this, we associate constant values to the SSA
130 names in the V_MAY_DEF and V_MUST_DEF operands for each store.
131 Additionally, since we also glob partial loads/stores with the base
132 symbol, we also keep track of the memory reference where the
133 constant value was stored (in the MEM_REF field of PROP_VALUE_T).
136 # a_5 = V_MAY_DEF <a_4>
142 In the example above, CCP will associate value '2' with 'a_5', but
143 it would be wrong to replace the load from 'a.b' with '2', because
144 '2' had been stored into a.a.
146 To support STORE-CCP, it is necessary to add a new value to the
147 constant propagation lattice. When evaluating a load for a memory
148 reference we can no longer assume a value of UNDEFINED if we
149 haven't seen a preceding store to the same memory location.
150 Consider, for instance global variables:
158 # A_5 = PHI (A_4, A_2);
166 The value of A_2 cannot be assumed to be UNDEFINED, as it may have
167 been defined outside of foo. If we were to assume it UNDEFINED, we
168 would erroneously optimize the above into 'return 3;'. Therefore,
169 when doing STORE-CCP, we introduce a fifth lattice value
170 (UNKNOWN_VAL), which overrides any other value when computing the
171 meet operation in PHI nodes.
173 Though STORE-CCP is not too expensive, it does have to do more work
174 than regular CCP, so it is only enabled at -O2. Both regular CCP
175 and STORE-CCP use the exact same algorithm. The only distinction
176 is that when doing STORE-CCP, the boolean variable DO_STORE_CCP is
177 set to true. This affects the evaluation of statements and PHI
182 Constant propagation with conditional branches,
183 Wegman and Zadeck, ACM TOPLAS 13(2):181-210.
185 Building an Optimizing Compiler,
186 Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9.
188 Advanced Compiler Design and Implementation,
189 Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */
193 #include "coretypes.h"
200 #include "basic-block.h"
203 #include "function.h"
204 #include "diagnostic.h"
206 #include "tree-dump.h"
207 #include "tree-flow.h"
208 #include "tree-pass.h"
209 #include "tree-ssa-propagate.h"
210 #include "langhooks.h"
214 /* Possible lattice values. */
224 /* Array of propagated constant values. After propagation,
225 CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If
226 the constant is held in an SSA name representing a memory store
227 (i.e., a V_MAY_DEF or V_MUST_DEF), CONST_VAL[I].MEM_REF will
228 contain the actual memory reference used to store (i.e., the LHS of
229 the assignment doing the store). */
230 static prop_value_t
*const_val
;
232 /* True if we are also propagating constants in stores and loads. */
233 static bool do_store_ccp
;
235 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */
238 dump_lattice_value (FILE *outf
, const char *prefix
, prop_value_t val
)
240 switch (val
.lattice_val
)
243 fprintf (outf
, "%sUNINITIALIZED", prefix
);
246 fprintf (outf
, "%sUNDEFINED", prefix
);
249 fprintf (outf
, "%sVARYING", prefix
);
252 fprintf (outf
, "%sUNKNOWN_VAL", prefix
);
255 fprintf (outf
, "%sCONSTANT ", prefix
);
256 print_generic_expr (outf
, val
.value
, dump_flags
);
264 /* Print lattice value VAL to stderr. */
266 void debug_lattice_value (prop_value_t val
);
269 debug_lattice_value (prop_value_t val
)
271 dump_lattice_value (stderr
, "", val
);
272 fprintf (stderr
, "\n");
276 /* Compute a default value for variable VAR and store it in the
277 CONST_VAL array. The following rules are used to get default
280 1- Global and static variables that are declared constant are
283 2- Any other value is considered UNDEFINED. This is useful when
284 considering PHI nodes. PHI arguments that are undefined do not
285 change the constant value of the PHI node, which allows for more
286 constants to be propagated.
288 3- If SSA_NAME_VALUE is set and it is a constant, its value is
291 4- Variables defined by statements other than assignments and PHI
292 nodes are considered VARYING.
294 5- Variables that are not GIMPLE registers are considered
295 UNKNOWN_VAL, which is really a stronger version of UNDEFINED.
296 It's used to avoid the short circuit evaluation implied by
297 UNDEFINED in ccp_lattice_meet. */
300 get_default_value (tree var
)
302 tree sym
= SSA_NAME_VAR (var
);
303 prop_value_t val
= { UNINITIALIZED
, NULL_TREE
, NULL_TREE
};
305 if (!do_store_ccp
&& !is_gimple_reg (var
))
307 /* Short circuit for regular CCP. We are not interested in any
308 non-register when DO_STORE_CCP is false. */
309 val
.lattice_val
= VARYING
;
311 else if (SSA_NAME_VALUE (var
)
312 && is_gimple_min_invariant (SSA_NAME_VALUE (var
)))
314 val
.lattice_val
= CONSTANT
;
315 val
.value
= SSA_NAME_VALUE (var
);
317 else if (TREE_STATIC (sym
)
318 && TREE_READONLY (sym
)
320 && DECL_INITIAL (sym
)
321 && is_gimple_min_invariant (DECL_INITIAL (sym
)))
323 /* Globals and static variables declared 'const' take their
325 val
.lattice_val
= CONSTANT
;
326 val
.value
= DECL_INITIAL (sym
);
331 tree stmt
= SSA_NAME_DEF_STMT (var
);
333 if (IS_EMPTY_STMT (stmt
))
335 /* Variables defined by an empty statement are those used
336 before being initialized. If VAR is a local variable, we
337 can assume initially that it is UNDEFINED. If we are
338 doing STORE-CCP, function arguments and non-register
339 variables are initially UNKNOWN_VAL, because we cannot
340 discard the value incoming from outside of this function
341 (see ccp_lattice_meet for details). */
342 if (is_gimple_reg (sym
) && TREE_CODE (sym
) != PARM_DECL
)
343 val
.lattice_val
= UNDEFINED
;
344 else if (do_store_ccp
)
345 val
.lattice_val
= UNKNOWN_VAL
;
347 val
.lattice_val
= VARYING
;
349 else if (TREE_CODE (stmt
) == MODIFY_EXPR
350 || TREE_CODE (stmt
) == PHI_NODE
)
352 /* Any other variable defined by an assignment or a PHI node
353 is considered UNDEFINED (or UNKNOWN_VAL if VAR is not a
355 val
.lattice_val
= is_gimple_reg (sym
) ? UNDEFINED
: UNKNOWN_VAL
;
359 /* Otherwise, VAR will never take on a constant value. */
360 val
.lattice_val
= VARYING
;
368 /* Get the constant value associated with variable VAR. If
369 MAY_USE_DEFAULT_P is true, call get_default_value on variables that
370 have the lattice value UNINITIALIZED. */
372 static prop_value_t
*
373 get_value (tree var
, bool may_use_default_p
)
375 prop_value_t
*val
= &const_val
[SSA_NAME_VERSION (var
)];
376 if (may_use_default_p
&& val
->lattice_val
== UNINITIALIZED
)
377 *val
= get_default_value (var
);
383 /* Set the value for variable VAR to NEW_VAL. Return true if the new
384 value is different from VAR's previous value. */
387 set_lattice_value (tree var
, prop_value_t new_val
)
389 prop_value_t
*old_val
= get_value (var
, false);
391 /* Lattice transitions must always be monotonically increasing in
392 value. We allow two exceptions:
394 1- If *OLD_VAL and NEW_VAL are the same, return false to
395 inform the caller that this was a non-transition.
397 2- If we are doing store-ccp (i.e., DOING_STORE_CCP is true),
398 allow CONSTANT->UNKNOWN_VAL. The UNKNOWN_VAL state is a
399 special type of UNDEFINED state which prevents the short
400 circuit evaluation of PHI arguments (see ccp_visit_phi_node
401 and ccp_lattice_meet). */
402 gcc_assert (old_val
->lattice_val
<= new_val
.lattice_val
403 || (old_val
->lattice_val
== new_val
.lattice_val
404 && old_val
->value
== new_val
.value
405 && old_val
->mem_ref
== new_val
.mem_ref
)
407 && old_val
->lattice_val
== CONSTANT
408 && new_val
.lattice_val
== UNKNOWN_VAL
));
410 if (old_val
->lattice_val
!= new_val
.lattice_val
)
412 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
414 dump_lattice_value (dump_file
, "Lattice value changed to ", new_val
);
415 fprintf (dump_file
, ". %sdding SSA edges to worklist.\n",
416 new_val
.lattice_val
!= UNDEFINED
? "A" : "Not a");
421 /* Transitions UNINITIALIZED -> UNDEFINED are never interesting
422 for propagation purposes. In these cases return false to
423 avoid doing useless work. */
424 return (new_val
.lattice_val
!= UNDEFINED
);
431 /* Return the likely CCP lattice value for STMT.
433 If STMT has no operands, then return CONSTANT.
435 Else if any operands of STMT are undefined, then return UNDEFINED.
437 Else if any operands of STMT are constants, then return CONSTANT.
439 Else return VARYING. */
442 likely_value (tree stmt
)
449 ann
= stmt_ann (stmt
);
451 /* If the statement has volatile operands, it won't fold to a
453 if (ann
->has_volatile_ops
)
456 /* If we are not doing store-ccp, statements with loads
457 and/or stores will never fold into a constant. */
459 && (ann
->makes_aliased_stores
460 || ann
->makes_aliased_loads
461 || !ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
)))
465 /* A CALL_EXPR is assumed to be varying. NOTE: This may be overly
466 conservative, in the presence of const and pure calls. */
467 if (get_call_expr_in (stmt
) != NULL_TREE
)
470 /* Anything other than assignments and conditional jumps are not
471 interesting for CCP. */
472 if (TREE_CODE (stmt
) != MODIFY_EXPR
473 && TREE_CODE (stmt
) != COND_EXPR
474 && TREE_CODE (stmt
) != SWITCH_EXPR
)
477 if (is_gimple_min_invariant (get_rhs (stmt
)))
480 found_constant
= false;
481 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, iter
, SSA_OP_USE
|SSA_OP_VUSE
)
483 prop_value_t
*val
= get_value (use
, true);
485 if (val
->lattice_val
== VARYING
)
488 if (val
->lattice_val
== UNKNOWN_VAL
)
490 /* UNKNOWN_VAL is invalid when not doing STORE-CCP. */
491 gcc_assert (do_store_ccp
);
495 if (val
->lattice_val
== CONSTANT
)
496 found_constant
= true;
500 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_USE
)
501 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_VUSE
))
508 /* Initialize local data structures for CCP. */
511 ccp_initialize (void)
515 const_val
= xmalloc (num_ssa_names
* sizeof (*const_val
));
516 memset (const_val
, 0, num_ssa_names
* sizeof (*const_val
));
518 /* Initialize simulation flags for PHI nodes and statements. */
521 block_stmt_iterator i
;
523 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
525 bool is_varying
= false;
526 tree stmt
= bsi_stmt (i
);
528 if (likely_value (stmt
) == VARYING
)
534 /* If the statement will not produce a constant, mark
535 all its outputs VARYING. */
536 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
537 get_value (def
, false)->lattice_val
= VARYING
;
539 /* Never mark conditional jumps with DONT_SIMULATE_AGAIN,
540 otherwise the propagator will never add the outgoing
542 if (TREE_CODE (stmt
) != COND_EXPR
543 && TREE_CODE (stmt
) != SWITCH_EXPR
)
547 DONT_SIMULATE_AGAIN (stmt
) = is_varying
;
551 /* Now process PHI nodes. */
556 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
560 prop_value_t
*val
= get_value (PHI_RESULT (phi
), false);
562 for (i
= 0; i
< PHI_NUM_ARGS (phi
); i
++)
564 arg
= PHI_ARG_DEF (phi
, i
);
566 if (TREE_CODE (arg
) == SSA_NAME
567 && get_value (arg
, false)->lattice_val
== VARYING
)
569 val
->lattice_val
= VARYING
;
574 DONT_SIMULATE_AGAIN (phi
) = (val
->lattice_val
== VARYING
);
580 /* Do final substitution of propagated values, cleanup the flowgraph and
581 free allocated storage. */
586 /* Perform substitutions based on the known constant values. */
587 substitute_and_fold (const_val
, false);
593 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
596 any M UNDEFINED = any
597 any M UNKNOWN_VAL = UNKNOWN_VAL
598 any M VARYING = VARYING
599 Ci M Cj = Ci if (i == j)
600 Ci M Cj = VARYING if (i != j)
602 Lattice values UNKNOWN_VAL and UNDEFINED are similar but have
603 different semantics at PHI nodes. Both values imply that we don't
604 know whether the variable is constant or not. However, UNKNOWN_VAL
605 values override all others. For instance, suppose that A is a
615 | A_3 = PHI (A_2, A_1)
620 If the edge into A_2 is not executable, the first visit to A_3 will
621 yield the constant 4. But the second visit to A_3 will be with A_2
622 in state UNKNOWN_VAL. We can no longer conclude that A_3 is 4
623 because A_2 may have been set in another function. If we had used
624 the lattice value UNDEFINED, we would have had wrongly concluded
629 ccp_lattice_meet (prop_value_t
*val1
, prop_value_t
*val2
)
631 if (val1
->lattice_val
== UNDEFINED
)
633 /* UNDEFINED M any = any */
636 else if (val2
->lattice_val
== UNDEFINED
)
638 /* any M UNDEFINED = any
639 Nothing to do. VAL1 already contains the value we want. */
642 else if (val1
->lattice_val
== UNKNOWN_VAL
643 || val2
->lattice_val
== UNKNOWN_VAL
)
645 /* UNKNOWN_VAL values are invalid if we are not doing STORE-CCP. */
646 gcc_assert (do_store_ccp
);
648 /* any M UNKNOWN_VAL = UNKNOWN_VAL. */
649 val1
->lattice_val
= UNKNOWN_VAL
;
650 val1
->value
= NULL_TREE
;
651 val1
->mem_ref
= NULL_TREE
;
653 else if (val1
->lattice_val
== VARYING
654 || val2
->lattice_val
== VARYING
)
656 /* any M VARYING = VARYING. */
657 val1
->lattice_val
= VARYING
;
658 val1
->value
= NULL_TREE
;
659 val1
->mem_ref
= NULL_TREE
;
661 else if (val1
->lattice_val
== CONSTANT
662 && val2
->lattice_val
== CONSTANT
663 && simple_cst_equal (val1
->value
, val2
->value
) == 1
665 || (val1
->mem_ref
&& val2
->mem_ref
666 && operand_equal_p (val1
->mem_ref
, val2
->mem_ref
, 0))))
668 /* Ci M Cj = Ci if (i == j)
669 Ci M Cj = VARYING if (i != j)
671 If these two values come from memory stores, make sure that
672 they come from the same memory reference. */
673 val1
->lattice_val
= CONSTANT
;
674 val1
->value
= val1
->value
;
675 val1
->mem_ref
= val1
->mem_ref
;
679 /* Any other combination is VARYING. */
680 val1
->lattice_val
= VARYING
;
681 val1
->value
= NULL_TREE
;
682 val1
->mem_ref
= NULL_TREE
;
687 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
688 lattice values to determine PHI_NODE's lattice value. The value of a
689 PHI node is determined calling ccp_lattice_meet with all the arguments
690 of the PHI node that are incoming via executable edges. */
692 static enum ssa_prop_result
693 ccp_visit_phi_node (tree phi
)
696 prop_value_t
*old_val
, new_val
;
698 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
700 fprintf (dump_file
, "\nVisiting PHI node: ");
701 print_generic_expr (dump_file
, phi
, dump_flags
);
704 old_val
= get_value (PHI_RESULT (phi
), false);
705 switch (old_val
->lattice_val
)
708 return SSA_PROP_VARYING
;
715 /* To avoid the default value of UNKNOWN_VAL overriding
716 that of its possible constant arguments, temporarily
717 set the PHI node's default lattice value to be
718 UNDEFINED. If the PHI node's old value was UNKNOWN_VAL and
719 the new value is UNDEFINED, then we prevent the invalid
720 transition by not calling set_lattice_value. */
721 gcc_assert (do_store_ccp
);
727 new_val
.lattice_val
= UNDEFINED
;
728 new_val
.value
= NULL_TREE
;
729 new_val
.mem_ref
= NULL_TREE
;
736 for (i
= 0; i
< PHI_NUM_ARGS (phi
); i
++)
738 /* Compute the meet operator over all the PHI arguments flowing
739 through executable edges. */
740 edge e
= PHI_ARG_EDGE (phi
, i
);
742 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
745 "\n Argument #%d (%d -> %d %sexecutable)\n",
746 i
, e
->src
->index
, e
->dest
->index
,
747 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
750 /* If the incoming edge is executable, Compute the meet operator for
751 the existing value of the PHI node and the current PHI argument. */
752 if (e
->flags
& EDGE_EXECUTABLE
)
754 tree arg
= PHI_ARG_DEF (phi
, i
);
755 prop_value_t arg_val
;
757 if (is_gimple_min_invariant (arg
))
759 arg_val
.lattice_val
= CONSTANT
;
761 arg_val
.mem_ref
= NULL_TREE
;
764 arg_val
= *(get_value (arg
, true));
766 ccp_lattice_meet (&new_val
, &arg_val
);
768 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
770 fprintf (dump_file
, "\t");
771 print_generic_expr (dump_file
, arg
, dump_flags
);
772 dump_lattice_value (dump_file
, "\tValue: ", arg_val
);
773 fprintf (dump_file
, "\n");
776 if (new_val
.lattice_val
== VARYING
)
781 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
783 dump_lattice_value (dump_file
, "\n PHI node value: ", new_val
);
784 fprintf (dump_file
, "\n\n");
787 /* Check for an invalid change from UNKNOWN_VAL to UNDEFINED. */
789 && old_val
->lattice_val
== UNKNOWN_VAL
790 && new_val
.lattice_val
== UNDEFINED
)
791 return SSA_PROP_NOT_INTERESTING
;
793 /* Otherwise, make the transition to the new value. */
794 if (set_lattice_value (PHI_RESULT (phi
), new_val
))
796 if (new_val
.lattice_val
== VARYING
)
797 return SSA_PROP_VARYING
;
799 return SSA_PROP_INTERESTING
;
802 return SSA_PROP_NOT_INTERESTING
;
806 /* CCP specific front-end to the non-destructive constant folding
809 Attempt to simplify the RHS of STMT knowing that one or more
810 operands are constants.
812 If simplification is possible, return the simplified RHS,
813 otherwise return the original RHS. */
818 tree rhs
= get_rhs (stmt
);
819 enum tree_code code
= TREE_CODE (rhs
);
820 enum tree_code_class kind
= TREE_CODE_CLASS (code
);
821 tree retval
= NULL_TREE
;
823 if (TREE_CODE (rhs
) == SSA_NAME
)
825 /* If the RHS is an SSA_NAME, return its known constant value,
827 return get_value (rhs
, true)->value
;
829 else if (do_store_ccp
&& stmt_makes_single_load (stmt
))
831 /* If the RHS is a memory load, see if the VUSEs associated with
832 it are a valid constant for that memory load. */
833 prop_value_t
*val
= get_value_loaded_by (stmt
, const_val
);
834 if (val
&& val
->mem_ref
835 && operand_equal_p (val
->mem_ref
, rhs
, 0))
841 /* Unary operators. Note that we know the single operand must
842 be a constant. So this should almost always return a
844 if (kind
== tcc_unary
)
846 /* Handle unary operators which can appear in GIMPLE form. */
847 tree op0
= TREE_OPERAND (rhs
, 0);
849 /* Simplify the operand down to a constant. */
850 if (TREE_CODE (op0
) == SSA_NAME
)
852 prop_value_t
*val
= get_value (op0
, true);
853 if (val
->lattice_val
== CONSTANT
)
854 op0
= get_value (op0
, true)->value
;
857 return fold_unary (code
, TREE_TYPE (rhs
), op0
);
860 /* Binary and comparison operators. We know one or both of the
861 operands are constants. */
862 else if (kind
== tcc_binary
863 || kind
== tcc_comparison
864 || code
== TRUTH_AND_EXPR
865 || code
== TRUTH_OR_EXPR
866 || code
== TRUTH_XOR_EXPR
)
868 /* Handle binary and comparison operators that can appear in
870 tree op0
= TREE_OPERAND (rhs
, 0);
871 tree op1
= TREE_OPERAND (rhs
, 1);
873 /* Simplify the operands down to constants when appropriate. */
874 if (TREE_CODE (op0
) == SSA_NAME
)
876 prop_value_t
*val
= get_value (op0
, true);
877 if (val
->lattice_val
== CONSTANT
)
881 if (TREE_CODE (op1
) == SSA_NAME
)
883 prop_value_t
*val
= get_value (op1
, true);
884 if (val
->lattice_val
== CONSTANT
)
888 return fold_binary (code
, TREE_TYPE (rhs
), op0
, op1
);
891 /* We may be able to fold away calls to builtin functions if their
892 arguments are constants. */
893 else if (code
== CALL_EXPR
894 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == ADDR_EXPR
895 && (TREE_CODE (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0))
897 && DECL_BUILT_IN (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0)))
899 if (!ZERO_SSA_OPERANDS (stmt
, SSA_OP_USE
))
902 tree fndecl
, arglist
;
907 /* Preserve the original values of every operand. */
908 orig
= xmalloc (sizeof (tree
) * NUM_SSA_OPERANDS (stmt
, SSA_OP_USE
));
909 FOR_EACH_SSA_TREE_OPERAND (var
, stmt
, iter
, SSA_OP_USE
)
912 /* Substitute operands with their values and try to fold. */
913 replace_uses_in (stmt
, NULL
, const_val
);
914 fndecl
= get_callee_fndecl (rhs
);
915 arglist
= TREE_OPERAND (rhs
, 1);
916 retval
= fold_builtin (fndecl
, arglist
, false);
918 /* Restore operands to their original form. */
920 FOR_EACH_SSA_USE_OPERAND (var_p
, stmt
, iter
, SSA_OP_USE
)
921 SET_USE (var_p
, orig
[i
++]);
928 /* If we got a simplified form, see if we need to convert its type. */
930 return fold_convert (TREE_TYPE (rhs
), retval
);
932 /* No simplification was possible. */
937 /* Return the tree representing the element referenced by T if T is an
938 ARRAY_REF or COMPONENT_REF into constant aggregates. Return
939 NULL_TREE otherwise. */
942 fold_const_aggregate_ref (tree t
)
945 tree base
, ctor
, idx
, field
;
946 unsigned HOST_WIDE_INT cnt
;
949 switch (TREE_CODE (t
))
952 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
953 DECL_INITIAL. If BASE is a nested reference into another
954 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
955 the inner reference. */
956 base
= TREE_OPERAND (t
, 0);
957 switch (TREE_CODE (base
))
960 if (!TREE_READONLY (base
)
961 || TREE_CODE (TREE_TYPE (base
)) != ARRAY_TYPE
962 || !targetm
.binds_local_p (base
))
965 ctor
= DECL_INITIAL (base
);
970 ctor
= fold_const_aggregate_ref (base
);
977 if (ctor
== NULL_TREE
978 || TREE_CODE (ctor
) != CONSTRUCTOR
979 || !TREE_STATIC (ctor
))
982 /* Get the index. If we have an SSA_NAME, try to resolve it
983 with the current lattice value for the SSA_NAME. */
984 idx
= TREE_OPERAND (t
, 1);
985 switch (TREE_CODE (idx
))
988 if ((value
= get_value (idx
, true))
989 && value
->lattice_val
== CONSTANT
990 && TREE_CODE (value
->value
) == INTEGER_CST
)
1003 /* Whoo-hoo! I'll fold ya baby. Yeah! */
1004 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor
), cnt
, cfield
, cval
)
1005 if (tree_int_cst_equal (cfield
, idx
))
1010 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1011 DECL_INITIAL. If BASE is a nested reference into another
1012 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1013 the inner reference. */
1014 base
= TREE_OPERAND (t
, 0);
1015 switch (TREE_CODE (base
))
1018 if (!TREE_READONLY (base
)
1019 || TREE_CODE (TREE_TYPE (base
)) != RECORD_TYPE
1020 || !targetm
.binds_local_p (base
))
1023 ctor
= DECL_INITIAL (base
);
1028 ctor
= fold_const_aggregate_ref (base
);
1035 if (ctor
== NULL_TREE
1036 || TREE_CODE (ctor
) != CONSTRUCTOR
1037 || !TREE_STATIC (ctor
))
1040 field
= TREE_OPERAND (t
, 1);
1042 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor
), cnt
, cfield
, cval
)
1044 /* FIXME: Handle bit-fields. */
1045 && ! DECL_BIT_FIELD (cfield
))
1056 /* Evaluate statement STMT. */
1059 evaluate_stmt (tree stmt
)
1063 ccp_lattice_t likelyvalue
= likely_value (stmt
);
1065 val
.mem_ref
= NULL_TREE
;
1067 /* If the statement is likely to have a CONSTANT result, then try
1068 to fold the statement to determine the constant value. */
1069 if (likelyvalue
== CONSTANT
)
1070 simplified
= ccp_fold (stmt
);
1071 /* If the statement is likely to have a VARYING result, then do not
1072 bother folding the statement. */
1073 else if (likelyvalue
== VARYING
)
1074 simplified
= get_rhs (stmt
);
1075 /* If the statement is an ARRAY_REF or COMPONENT_REF into constant
1076 aggregates, extract the referenced constant. Otherwise the
1077 statement is likely to have an UNDEFINED value, and there will be
1078 nothing to do. Note that fold_const_aggregate_ref returns
1079 NULL_TREE if the first case does not match. */
1081 simplified
= fold_const_aggregate_ref (get_rhs (stmt
));
1083 if (simplified
&& is_gimple_min_invariant (simplified
))
1085 /* The statement produced a constant value. */
1086 val
.lattice_val
= CONSTANT
;
1087 val
.value
= simplified
;
1091 /* The statement produced a nonconstant value. If the statement
1092 had UNDEFINED operands, then the result of the statement
1093 should be UNDEFINED. Otherwise, the statement is VARYING. */
1094 if (likelyvalue
== UNDEFINED
|| likelyvalue
== UNKNOWN_VAL
)
1095 val
.lattice_val
= likelyvalue
;
1097 val
.lattice_val
= VARYING
;
1099 val
.value
= NULL_TREE
;
1106 /* Visit the assignment statement STMT. Set the value of its LHS to the
1107 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
1108 creates virtual definitions, set the value of each new name to that
1109 of the RHS (if we can derive a constant out of the RHS). */
1111 static enum ssa_prop_result
1112 visit_assignment (tree stmt
, tree
*output_p
)
1116 enum ssa_prop_result retval
;
1118 lhs
= TREE_OPERAND (stmt
, 0);
1119 rhs
= TREE_OPERAND (stmt
, 1);
1121 if (TREE_CODE (rhs
) == SSA_NAME
)
1123 /* For a simple copy operation, we copy the lattice values. */
1124 prop_value_t
*nval
= get_value (rhs
, true);
1127 else if (do_store_ccp
&& stmt_makes_single_load (stmt
))
1129 /* Same as above, but the RHS is not a gimple register and yet
1130 has a known VUSE. If STMT is loading from the same memory
1131 location that created the SSA_NAMEs for the virtual operands,
1132 we can propagate the value on the RHS. */
1133 prop_value_t
*nval
= get_value_loaded_by (stmt
, const_val
);
1135 if (nval
&& nval
->mem_ref
1136 && operand_equal_p (nval
->mem_ref
, rhs
, 0))
1139 val
= evaluate_stmt (stmt
);
1142 /* Evaluate the statement. */
1143 val
= evaluate_stmt (stmt
);
1145 /* If the original LHS was a VIEW_CONVERT_EXPR, modify the constant
1146 value to be a VIEW_CONVERT_EXPR of the old constant value.
1148 ??? Also, if this was a definition of a bitfield, we need to widen
1149 the constant value into the type of the destination variable. This
1150 should not be necessary if GCC represented bitfields properly. */
1152 tree orig_lhs
= TREE_OPERAND (stmt
, 0);
1154 if (TREE_CODE (orig_lhs
) == VIEW_CONVERT_EXPR
1155 && val
.lattice_val
== CONSTANT
)
1157 tree w
= fold_build1 (VIEW_CONVERT_EXPR
,
1158 TREE_TYPE (TREE_OPERAND (orig_lhs
, 0)),
1161 orig_lhs
= TREE_OPERAND (orig_lhs
, 0);
1162 if (w
&& is_gimple_min_invariant (w
))
1166 val
.lattice_val
= VARYING
;
1171 if (val
.lattice_val
== CONSTANT
1172 && TREE_CODE (orig_lhs
) == COMPONENT_REF
1173 && DECL_BIT_FIELD (TREE_OPERAND (orig_lhs
, 1)))
1175 tree w
= widen_bitfield (val
.value
, TREE_OPERAND (orig_lhs
, 1),
1178 if (w
&& is_gimple_min_invariant (w
))
1182 val
.lattice_val
= VARYING
;
1183 val
.value
= NULL_TREE
;
1184 val
.mem_ref
= NULL_TREE
;
1189 retval
= SSA_PROP_NOT_INTERESTING
;
1191 /* Set the lattice value of the statement's output. */
1192 if (TREE_CODE (lhs
) == SSA_NAME
)
1194 /* If STMT is an assignment to an SSA_NAME, we only have one
1196 if (set_lattice_value (lhs
, val
))
1199 if (val
.lattice_val
== VARYING
)
1200 retval
= SSA_PROP_VARYING
;
1202 retval
= SSA_PROP_INTERESTING
;
1205 else if (do_store_ccp
&& stmt_makes_single_store (stmt
))
1207 /* Otherwise, set the names in V_MAY_DEF/V_MUST_DEF operands
1208 to the new constant value and mark the LHS as the memory
1209 reference associated with VAL. */
1214 /* Stores cannot take on an UNDEFINED value. */
1215 if (val
.lattice_val
== UNDEFINED
)
1216 val
.lattice_val
= UNKNOWN_VAL
;
1218 /* Mark VAL as stored in the LHS of this assignment. */
1221 /* Set the value of every VDEF to VAL. */
1223 FOR_EACH_SSA_TREE_OPERAND (vdef
, stmt
, i
, SSA_OP_VIRTUAL_DEFS
)
1224 changed
|= set_lattice_value (vdef
, val
);
1226 /* Note that for propagation purposes, we are only interested in
1227 visiting statements that load the exact same memory reference
1228 stored here. Those statements will have the exact same list
1229 of virtual uses, so it is enough to set the output of this
1230 statement to be its first virtual definition. */
1231 *output_p
= first_vdef (stmt
);
1234 if (val
.lattice_val
== VARYING
)
1235 retval
= SSA_PROP_VARYING
;
1237 retval
= SSA_PROP_INTERESTING
;
1245 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
1246 if it can determine which edge will be taken. Otherwise, return
1247 SSA_PROP_VARYING. */
1249 static enum ssa_prop_result
1250 visit_cond_stmt (tree stmt
, edge
*taken_edge_p
)
1255 block
= bb_for_stmt (stmt
);
1256 val
= evaluate_stmt (stmt
);
1258 /* Find which edge out of the conditional block will be taken and add it
1259 to the worklist. If no single edge can be determined statically,
1260 return SSA_PROP_VARYING to feed all the outgoing edges to the
1261 propagation engine. */
1262 *taken_edge_p
= val
.value
? find_taken_edge (block
, val
.value
) : 0;
1264 return SSA_PROP_INTERESTING
;
1266 return SSA_PROP_VARYING
;
1270 /* Evaluate statement STMT. If the statement produces an output value and
1271 its evaluation changes the lattice value of its output, return
1272 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
1275 If STMT is a conditional branch and we can determine its truth
1276 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
1277 value, return SSA_PROP_VARYING. */
1279 static enum ssa_prop_result
1280 ccp_visit_stmt (tree stmt
, edge
*taken_edge_p
, tree
*output_p
)
1285 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1287 fprintf (dump_file
, "\nVisiting statement:\n");
1288 print_generic_stmt (dump_file
, stmt
, dump_flags
);
1289 fprintf (dump_file
, "\n");
1292 if (TREE_CODE (stmt
) == MODIFY_EXPR
)
1294 /* If the statement is an assignment that produces a single
1295 output value, evaluate its RHS to see if the lattice value of
1296 its output has changed. */
1297 return visit_assignment (stmt
, output_p
);
1299 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
1301 /* If STMT is a conditional branch, see if we can determine
1302 which branch will be taken. */
1303 return visit_cond_stmt (stmt
, taken_edge_p
);
1306 /* Any other kind of statement is not interesting for constant
1307 propagation and, therefore, not worth simulating. */
1308 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1309 fprintf (dump_file
, "No interesting values produced. Marked VARYING.\n");
1311 /* Definitions made by statements other than assignments to
1312 SSA_NAMEs represent unknown modifications to their outputs.
1313 Mark them VARYING. */
1314 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
1316 prop_value_t v
= { VARYING
, NULL_TREE
, NULL_TREE
};
1317 set_lattice_value (def
, v
);
1320 return SSA_PROP_VARYING
;
1324 /* Main entry point for SSA Conditional Constant Propagation. */
1327 execute_ssa_ccp (bool store_ccp
)
1329 do_store_ccp
= store_ccp
;
1331 ssa_propagate (ccp_visit_stmt
, ccp_visit_phi_node
);
1339 execute_ssa_ccp (false);
1346 return flag_tree_ccp
!= 0;
1350 struct tree_opt_pass pass_ccp
=
1353 gate_ccp
, /* gate */
1354 do_ssa_ccp
, /* execute */
1357 0, /* static_pass_number */
1358 TV_TREE_CCP
, /* tv_id */
1359 PROP_cfg
| PROP_ssa
| PROP_alias
, /* properties_required */
1360 0, /* properties_provided */
1361 0, /* properties_destroyed */
1362 0, /* todo_flags_start */
1363 TODO_cleanup_cfg
| TODO_dump_func
| TODO_update_ssa
1364 | TODO_ggc_collect
| TODO_verify_ssa
1365 | TODO_verify_stmts
, /* todo_flags_finish */
1371 do_ssa_store_ccp (void)
1373 /* If STORE-CCP is not enabled, we just run regular CCP. */
1374 execute_ssa_ccp (flag_tree_store_ccp
!= 0);
1378 gate_store_ccp (void)
1380 /* STORE-CCP is enabled only with -ftree-store-ccp, but when
1381 -fno-tree-store-ccp is specified, we should run regular CCP.
1382 That's why the pass is enabled with either flag. */
1383 return flag_tree_store_ccp
!= 0 || flag_tree_ccp
!= 0;
1387 struct tree_opt_pass pass_store_ccp
=
1389 "store_ccp", /* name */
1390 gate_store_ccp
, /* gate */
1391 do_ssa_store_ccp
, /* execute */
1394 0, /* static_pass_number */
1395 TV_TREE_STORE_CCP
, /* tv_id */
1396 PROP_cfg
| PROP_ssa
| PROP_alias
, /* properties_required */
1397 0, /* properties_provided */
1398 0, /* properties_destroyed */
1399 0, /* todo_flags_start */
1400 TODO_dump_func
| TODO_update_ssa
1401 | TODO_ggc_collect
| TODO_verify_ssa
1403 | TODO_verify_stmts
, /* todo_flags_finish */
1407 /* Given a constant value VAL for bitfield FIELD, and a destination
1408 variable VAR, return VAL appropriately widened to fit into VAR. If
1409 FIELD is wider than HOST_WIDE_INT, NULL is returned. */
1412 widen_bitfield (tree val
, tree field
, tree var
)
1414 unsigned HOST_WIDE_INT var_size
, field_size
;
1416 unsigned HOST_WIDE_INT mask
;
1419 /* We can only do this if the size of the type and field and VAL are
1420 all constants representable in HOST_WIDE_INT. */
1421 if (!host_integerp (TYPE_SIZE (TREE_TYPE (var
)), 1)
1422 || !host_integerp (DECL_SIZE (field
), 1)
1423 || !host_integerp (val
, 0))
1426 var_size
= tree_low_cst (TYPE_SIZE (TREE_TYPE (var
)), 1);
1427 field_size
= tree_low_cst (DECL_SIZE (field
), 1);
1429 /* Give up if either the bitfield or the variable are too wide. */
1430 if (field_size
> HOST_BITS_PER_WIDE_INT
|| var_size
> HOST_BITS_PER_WIDE_INT
)
1433 gcc_assert (var_size
>= field_size
);
1435 /* If the sign bit of the value is not set or the field's type is unsigned,
1436 just mask off the high order bits of the value. */
1437 if (DECL_UNSIGNED (field
)
1438 || !(tree_low_cst (val
, 0) & (((HOST_WIDE_INT
)1) << (field_size
- 1))))
1440 /* Zero extension. Build a mask with the lower 'field_size' bits
1441 set and a BIT_AND_EXPR node to clear the high order bits of
1443 for (i
= 0, mask
= 0; i
< field_size
; i
++)
1444 mask
|= ((HOST_WIDE_INT
) 1) << i
;
1446 wide_val
= fold_build2 (BIT_AND_EXPR
, TREE_TYPE (var
), val
,
1447 build_int_cst (TREE_TYPE (var
), mask
));
1451 /* Sign extension. Create a mask with the upper 'field_size'
1452 bits set and a BIT_IOR_EXPR to set the high order bits of the
1454 for (i
= 0, mask
= 0; i
< (var_size
- field_size
); i
++)
1455 mask
|= ((HOST_WIDE_INT
) 1) << (var_size
- i
- 1);
1457 wide_val
= fold_build2 (BIT_IOR_EXPR
, TREE_TYPE (var
), val
,
1458 build_int_cst (TREE_TYPE (var
), mask
));
1465 /* A subroutine of fold_stmt_r. Attempts to fold *(A+O) to A[X].
1466 BASE is an array type. OFFSET is a byte displacement. ORIG_TYPE
1467 is the desired result type. */
1470 maybe_fold_offset_to_array_ref (tree base
, tree offset
, tree orig_type
)
1472 tree min_idx
, idx
, elt_offset
= integer_zero_node
;
1473 tree array_type
, elt_type
, elt_size
;
1475 /* If BASE is an ARRAY_REF, we can pick up another offset (this time
1476 measured in units of the size of elements type) from that ARRAY_REF).
1477 We can't do anything if either is variable.
1479 The case we handle here is *(&A[N]+O). */
1480 if (TREE_CODE (base
) == ARRAY_REF
)
1482 tree low_bound
= array_ref_low_bound (base
);
1484 elt_offset
= TREE_OPERAND (base
, 1);
1485 if (TREE_CODE (low_bound
) != INTEGER_CST
1486 || TREE_CODE (elt_offset
) != INTEGER_CST
)
1489 elt_offset
= int_const_binop (MINUS_EXPR
, elt_offset
, low_bound
, 0);
1490 base
= TREE_OPERAND (base
, 0);
1493 /* Ignore stupid user tricks of indexing non-array variables. */
1494 array_type
= TREE_TYPE (base
);
1495 if (TREE_CODE (array_type
) != ARRAY_TYPE
)
1497 elt_type
= TREE_TYPE (array_type
);
1498 if (!lang_hooks
.types_compatible_p (orig_type
, elt_type
))
1501 /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the
1502 element type (so we can use the alignment if it's not constant).
1503 Otherwise, compute the offset as an index by using a division. If the
1504 division isn't exact, then don't do anything. */
1505 elt_size
= TYPE_SIZE_UNIT (elt_type
);
1506 if (integer_zerop (offset
))
1508 if (TREE_CODE (elt_size
) != INTEGER_CST
)
1509 elt_size
= size_int (TYPE_ALIGN (elt_type
));
1511 idx
= integer_zero_node
;
1515 unsigned HOST_WIDE_INT lquo
, lrem
;
1516 HOST_WIDE_INT hquo
, hrem
;
1518 if (TREE_CODE (elt_size
) != INTEGER_CST
1519 || div_and_round_double (TRUNC_DIV_EXPR
, 1,
1520 TREE_INT_CST_LOW (offset
),
1521 TREE_INT_CST_HIGH (offset
),
1522 TREE_INT_CST_LOW (elt_size
),
1523 TREE_INT_CST_HIGH (elt_size
),
1524 &lquo
, &hquo
, &lrem
, &hrem
)
1528 idx
= build_int_cst_wide (NULL_TREE
, lquo
, hquo
);
1531 /* Assume the low bound is zero. If there is a domain type, get the
1532 low bound, if any, convert the index into that type, and add the
1534 min_idx
= integer_zero_node
;
1535 if (TYPE_DOMAIN (array_type
))
1537 if (TYPE_MIN_VALUE (TYPE_DOMAIN (array_type
)))
1538 min_idx
= TYPE_MIN_VALUE (TYPE_DOMAIN (array_type
));
1540 min_idx
= fold_convert (TYPE_DOMAIN (array_type
), min_idx
);
1542 if (TREE_CODE (min_idx
) != INTEGER_CST
)
1545 idx
= fold_convert (TYPE_DOMAIN (array_type
), idx
);
1546 elt_offset
= fold_convert (TYPE_DOMAIN (array_type
), elt_offset
);
1549 if (!integer_zerop (min_idx
))
1550 idx
= int_const_binop (PLUS_EXPR
, idx
, min_idx
, 0);
1551 if (!integer_zerop (elt_offset
))
1552 idx
= int_const_binop (PLUS_EXPR
, idx
, elt_offset
, 0);
1554 return build (ARRAY_REF
, orig_type
, base
, idx
, min_idx
,
1555 size_int (tree_low_cst (elt_size
, 1)
1556 / (TYPE_ALIGN_UNIT (elt_type
))));
1560 /* A subroutine of fold_stmt_r. Attempts to fold *(S+O) to S.X.
1561 BASE is a record type. OFFSET is a byte displacement. ORIG_TYPE
1562 is the desired result type. */
1563 /* ??? This doesn't handle class inheritance. */
1566 maybe_fold_offset_to_component_ref (tree record_type
, tree base
, tree offset
,
1567 tree orig_type
, bool base_is_ptr
)
1569 tree f
, t
, field_type
, tail_array_field
, field_offset
;
1571 if (TREE_CODE (record_type
) != RECORD_TYPE
1572 && TREE_CODE (record_type
) != UNION_TYPE
1573 && TREE_CODE (record_type
) != QUAL_UNION_TYPE
)
1576 /* Short-circuit silly cases. */
1577 if (lang_hooks
.types_compatible_p (record_type
, orig_type
))
1580 tail_array_field
= NULL_TREE
;
1581 for (f
= TYPE_FIELDS (record_type
); f
; f
= TREE_CHAIN (f
))
1585 if (TREE_CODE (f
) != FIELD_DECL
)
1587 if (DECL_BIT_FIELD (f
))
1590 field_offset
= byte_position (f
);
1591 if (TREE_CODE (field_offset
) != INTEGER_CST
)
1594 /* ??? Java creates "interesting" fields for representing base classes.
1595 They have no name, and have no context. With no context, we get into
1596 trouble with nonoverlapping_component_refs_p. Skip them. */
1597 if (!DECL_FIELD_CONTEXT (f
))
1600 /* The previous array field isn't at the end. */
1601 tail_array_field
= NULL_TREE
;
1603 /* Check to see if this offset overlaps with the field. */
1604 cmp
= tree_int_cst_compare (field_offset
, offset
);
1608 field_type
= TREE_TYPE (f
);
1610 /* Here we exactly match the offset being checked. If the types match,
1611 then we can return that field. */
1613 && lang_hooks
.types_compatible_p (orig_type
, field_type
))
1616 base
= build1 (INDIRECT_REF
, record_type
, base
);
1617 t
= build (COMPONENT_REF
, field_type
, base
, f
, NULL_TREE
);
1621 /* Don't care about offsets into the middle of scalars. */
1622 if (!AGGREGATE_TYPE_P (field_type
))
1625 /* Check for array at the end of the struct. This is often
1626 used as for flexible array members. We should be able to
1627 turn this into an array access anyway. */
1628 if (TREE_CODE (field_type
) == ARRAY_TYPE
)
1629 tail_array_field
= f
;
1631 /* Check the end of the field against the offset. */
1632 if (!DECL_SIZE_UNIT (f
)
1633 || TREE_CODE (DECL_SIZE_UNIT (f
)) != INTEGER_CST
)
1635 t
= int_const_binop (MINUS_EXPR
, offset
, field_offset
, 1);
1636 if (!tree_int_cst_lt (t
, DECL_SIZE_UNIT (f
)))
1639 /* If we matched, then set offset to the displacement into
1645 if (!tail_array_field
)
1648 f
= tail_array_field
;
1649 field_type
= TREE_TYPE (f
);
1650 offset
= int_const_binop (MINUS_EXPR
, offset
, byte_position (f
), 1);
1653 /* If we get here, we've got an aggregate field, and a possibly
1654 nonzero offset into them. Recurse and hope for a valid match. */
1656 base
= build1 (INDIRECT_REF
, record_type
, base
);
1657 base
= build (COMPONENT_REF
, field_type
, base
, f
, NULL_TREE
);
1659 t
= maybe_fold_offset_to_array_ref (base
, offset
, orig_type
);
1662 return maybe_fold_offset_to_component_ref (field_type
, base
, offset
,
1667 /* A subroutine of fold_stmt_r. Attempt to simplify *(BASE+OFFSET).
1668 Return the simplified expression, or NULL if nothing could be done. */
1671 maybe_fold_stmt_indirect (tree expr
, tree base
, tree offset
)
1675 /* We may well have constructed a double-nested PLUS_EXPR via multiple
1676 substitutions. Fold that down to one. Remove NON_LVALUE_EXPRs that
1677 are sometimes added. */
1679 STRIP_TYPE_NOPS (base
);
1680 TREE_OPERAND (expr
, 0) = base
;
1682 /* One possibility is that the address reduces to a string constant. */
1683 t
= fold_read_from_constant_string (expr
);
1687 /* Add in any offset from a PLUS_EXPR. */
1688 if (TREE_CODE (base
) == PLUS_EXPR
)
1692 offset2
= TREE_OPERAND (base
, 1);
1693 if (TREE_CODE (offset2
) != INTEGER_CST
)
1695 base
= TREE_OPERAND (base
, 0);
1697 offset
= int_const_binop (PLUS_EXPR
, offset
, offset2
, 1);
1700 if (TREE_CODE (base
) == ADDR_EXPR
)
1702 /* Strip the ADDR_EXPR. */
1703 base
= TREE_OPERAND (base
, 0);
1705 /* Fold away CONST_DECL to its value, if the type is scalar. */
1706 if (TREE_CODE (base
) == CONST_DECL
1707 && is_gimple_min_invariant (DECL_INITIAL (base
)))
1708 return DECL_INITIAL (base
);
1710 /* Try folding *(&B+O) to B[X]. */
1711 t
= maybe_fold_offset_to_array_ref (base
, offset
, TREE_TYPE (expr
));
1715 /* Try folding *(&B+O) to B.X. */
1716 t
= maybe_fold_offset_to_component_ref (TREE_TYPE (base
), base
, offset
,
1717 TREE_TYPE (expr
), false);
1721 /* Fold *&B to B. We can only do this if EXPR is the same type
1722 as BASE. We can't do this if EXPR is the element type of an array
1723 and BASE is the array. */
1724 if (integer_zerop (offset
)
1725 && lang_hooks
.types_compatible_p (TREE_TYPE (base
),
1731 /* We can get here for out-of-range string constant accesses,
1732 such as "_"[3]. Bail out of the entire substitution search
1733 and arrange for the entire statement to be replaced by a
1734 call to __builtin_trap. In all likelihood this will all be
1735 constant-folded away, but in the meantime we can't leave with
1736 something that get_expr_operands can't understand. */
1740 if (TREE_CODE (t
) == ADDR_EXPR
1741 && TREE_CODE (TREE_OPERAND (t
, 0)) == STRING_CST
)
1743 /* FIXME: Except that this causes problems elsewhere with dead
1744 code not being deleted, and we die in the rtl expanders
1745 because we failed to remove some ssa_name. In the meantime,
1746 just return zero. */
1747 /* FIXME2: This condition should be signaled by
1748 fold_read_from_constant_string directly, rather than
1749 re-checking for it here. */
1750 return integer_zero_node
;
1753 /* Try folding *(B+O) to B->X. Still an improvement. */
1754 if (POINTER_TYPE_P (TREE_TYPE (base
)))
1756 t
= maybe_fold_offset_to_component_ref (TREE_TYPE (TREE_TYPE (base
)),
1758 TREE_TYPE (expr
), true);
1764 /* Otherwise we had an offset that we could not simplify. */
1769 /* A subroutine of fold_stmt_r. EXPR is a PLUS_EXPR.
1771 A quaint feature extant in our address arithmetic is that there
1772 can be hidden type changes here. The type of the result need
1773 not be the same as the type of the input pointer.
1775 What we're after here is an expression of the form
1776 (T *)(&array + const)
1777 where the cast doesn't actually exist, but is implicit in the
1778 type of the PLUS_EXPR. We'd like to turn this into
1780 which may be able to propagate further. */
1783 maybe_fold_stmt_addition (tree expr
)
1785 tree op0
= TREE_OPERAND (expr
, 0);
1786 tree op1
= TREE_OPERAND (expr
, 1);
1787 tree ptr_type
= TREE_TYPE (expr
);
1790 bool subtract
= (TREE_CODE (expr
) == MINUS_EXPR
);
1792 /* We're only interested in pointer arithmetic. */
1793 if (!POINTER_TYPE_P (ptr_type
))
1795 /* Canonicalize the integral operand to op1. */
1796 if (INTEGRAL_TYPE_P (TREE_TYPE (op0
)))
1800 t
= op0
, op0
= op1
, op1
= t
;
1802 /* It had better be a constant. */
1803 if (TREE_CODE (op1
) != INTEGER_CST
)
1805 /* The first operand should be an ADDR_EXPR. */
1806 if (TREE_CODE (op0
) != ADDR_EXPR
)
1808 op0
= TREE_OPERAND (op0
, 0);
1810 /* If the first operand is an ARRAY_REF, expand it so that we can fold
1811 the offset into it. */
1812 while (TREE_CODE (op0
) == ARRAY_REF
)
1814 tree array_obj
= TREE_OPERAND (op0
, 0);
1815 tree array_idx
= TREE_OPERAND (op0
, 1);
1816 tree elt_type
= TREE_TYPE (op0
);
1817 tree elt_size
= TYPE_SIZE_UNIT (elt_type
);
1820 if (TREE_CODE (array_idx
) != INTEGER_CST
)
1822 if (TREE_CODE (elt_size
) != INTEGER_CST
)
1825 /* Un-bias the index by the min index of the array type. */
1826 min_idx
= TYPE_DOMAIN (TREE_TYPE (array_obj
));
1829 min_idx
= TYPE_MIN_VALUE (min_idx
);
1832 if (TREE_CODE (min_idx
) != INTEGER_CST
)
1835 array_idx
= convert (TREE_TYPE (min_idx
), array_idx
);
1836 if (!integer_zerop (min_idx
))
1837 array_idx
= int_const_binop (MINUS_EXPR
, array_idx
,
1842 /* Convert the index to a byte offset. */
1843 array_idx
= convert (sizetype
, array_idx
);
1844 array_idx
= int_const_binop (MULT_EXPR
, array_idx
, elt_size
, 0);
1846 /* Update the operands for the next round, or for folding. */
1847 /* If we're manipulating unsigned types, then folding into negative
1848 values can produce incorrect results. Particularly if the type
1849 is smaller than the width of the pointer. */
1851 && TYPE_UNSIGNED (TREE_TYPE (op1
))
1852 && tree_int_cst_lt (array_idx
, op1
))
1854 op1
= int_const_binop (subtract
? MINUS_EXPR
: PLUS_EXPR
,
1860 /* If we weren't able to fold the subtraction into another array reference,
1861 canonicalize the integer for passing to the array and component ref
1862 simplification functions. */
1865 if (TYPE_UNSIGNED (TREE_TYPE (op1
)))
1867 op1
= fold_build1 (NEGATE_EXPR
, TREE_TYPE (op1
), op1
);
1868 /* ??? In theory fold should always produce another integer. */
1869 if (TREE_CODE (op1
) != INTEGER_CST
)
1873 ptd_type
= TREE_TYPE (ptr_type
);
1875 /* At which point we can try some of the same things as for indirects. */
1876 t
= maybe_fold_offset_to_array_ref (op0
, op1
, ptd_type
);
1878 t
= maybe_fold_offset_to_component_ref (TREE_TYPE (op0
), op0
, op1
,
1881 t
= build1 (ADDR_EXPR
, ptr_type
, t
);
1886 /* Subroutine of fold_stmt called via walk_tree. We perform several
1887 simplifications of EXPR_P, mostly having to do with pointer arithmetic. */
1890 fold_stmt_r (tree
*expr_p
, int *walk_subtrees
, void *data
)
1892 bool *changed_p
= data
;
1893 tree expr
= *expr_p
, t
;
1895 /* ??? It'd be nice if walk_tree had a pre-order option. */
1896 switch (TREE_CODE (expr
))
1899 t
= walk_tree (&TREE_OPERAND (expr
, 0), fold_stmt_r
, data
, NULL
);
1904 t
= maybe_fold_stmt_indirect (expr
, TREE_OPERAND (expr
, 0),
1908 /* ??? Could handle ARRAY_REF here, as a variant of INDIRECT_REF.
1909 We'd only want to bother decomposing an existing ARRAY_REF if
1910 the base array is found to have another offset contained within.
1911 Otherwise we'd be wasting time. */
1914 t
= walk_tree (&TREE_OPERAND (expr
, 0), fold_stmt_r
, data
, NULL
);
1919 /* Set TREE_INVARIANT properly so that the value is properly
1920 considered constant, and so gets propagated as expected. */
1922 recompute_tree_invarant_for_addr_expr (expr
);
1927 t
= walk_tree (&TREE_OPERAND (expr
, 0), fold_stmt_r
, data
, NULL
);
1930 t
= walk_tree (&TREE_OPERAND (expr
, 1), fold_stmt_r
, data
, NULL
);
1935 t
= maybe_fold_stmt_addition (expr
);
1939 t
= walk_tree (&TREE_OPERAND (expr
, 0), fold_stmt_r
, data
, NULL
);
1944 /* Make sure the FIELD_DECL is actually a field in the type on the lhs.
1945 We've already checked that the records are compatible, so we should
1946 come up with a set of compatible fields. */
1948 tree expr_record
= TREE_TYPE (TREE_OPERAND (expr
, 0));
1949 tree expr_field
= TREE_OPERAND (expr
, 1);
1951 if (DECL_FIELD_CONTEXT (expr_field
) != TYPE_MAIN_VARIANT (expr_record
))
1953 expr_field
= find_compatible_field (expr_record
, expr_field
);
1954 TREE_OPERAND (expr
, 1) = expr_field
;
1959 case TARGET_MEM_REF
:
1960 t
= maybe_fold_tmr (expr
);
1977 /* Return the string length, maximum string length or maximum value of
1979 If ARG is an SSA name variable, follow its use-def chains. If LENGTH
1980 is not NULL and, for TYPE == 0, its value is not equal to the length
1981 we determine or if we are unable to determine the length or value,
1982 return false. VISITED is a bitmap of visited variables.
1983 TYPE is 0 if string length should be returned, 1 for maximum string
1984 length and 2 for maximum value ARG can have. */
1987 get_maxval_strlen (tree arg
, tree
*length
, bitmap visited
, int type
)
1989 tree var
, def_stmt
, val
;
1991 if (TREE_CODE (arg
) != SSA_NAME
)
1996 if (TREE_CODE (val
) != INTEGER_CST
1997 || tree_int_cst_sgn (val
) < 0)
2001 val
= c_strlen (arg
, 1);
2009 if (TREE_CODE (*length
) != INTEGER_CST
2010 || TREE_CODE (val
) != INTEGER_CST
)
2013 if (tree_int_cst_lt (*length
, val
))
2017 else if (simple_cst_equal (val
, *length
) != 1)
2025 /* If we were already here, break the infinite cycle. */
2026 if (bitmap_bit_p (visited
, SSA_NAME_VERSION (arg
)))
2028 bitmap_set_bit (visited
, SSA_NAME_VERSION (arg
));
2031 def_stmt
= SSA_NAME_DEF_STMT (var
);
2033 switch (TREE_CODE (def_stmt
))
2039 /* The RHS of the statement defining VAR must either have a
2040 constant length or come from another SSA_NAME with a constant
2042 rhs
= TREE_OPERAND (def_stmt
, 1);
2044 return get_maxval_strlen (rhs
, length
, visited
, type
);
2049 /* All the arguments of the PHI node must have the same constant
2053 for (i
= 0; i
< PHI_NUM_ARGS (def_stmt
); i
++)
2055 tree arg
= PHI_ARG_DEF (def_stmt
, i
);
2057 /* If this PHI has itself as an argument, we cannot
2058 determine the string length of this argument. However,
2059 if we can find a constant string length for the other
2060 PHI args then we can still be sure that this is a
2061 constant string length. So be optimistic and just
2062 continue with the next argument. */
2063 if (arg
== PHI_RESULT (def_stmt
))
2066 if (!get_maxval_strlen (arg
, length
, visited
, type
))
2082 /* Fold builtin call FN in statement STMT. If it cannot be folded into a
2083 constant, return NULL_TREE. Otherwise, return its constant value. */
2086 ccp_fold_builtin (tree stmt
, tree fn
)
2088 tree result
, val
[3];
2089 tree callee
, arglist
, a
;
2090 int arg_mask
, i
, type
;
2094 ignore
= TREE_CODE (stmt
) != MODIFY_EXPR
;
2096 /* First try the generic builtin folder. If that succeeds, return the
2098 callee
= get_callee_fndecl (fn
);
2099 arglist
= TREE_OPERAND (fn
, 1);
2100 result
= fold_builtin (callee
, arglist
, ignore
);
2104 STRIP_NOPS (result
);
2108 /* Ignore MD builtins. */
2109 if (DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_MD
)
2112 /* If the builtin could not be folded, and it has no argument list,
2117 /* Limit the work only for builtins we know how to simplify. */
2118 switch (DECL_FUNCTION_CODE (callee
))
2120 case BUILT_IN_STRLEN
:
2121 case BUILT_IN_FPUTS
:
2122 case BUILT_IN_FPUTS_UNLOCKED
:
2126 case BUILT_IN_STRCPY
:
2127 case BUILT_IN_STRNCPY
:
2131 case BUILT_IN_MEMCPY_CHK
:
2132 case BUILT_IN_MEMPCPY_CHK
:
2133 case BUILT_IN_MEMMOVE_CHK
:
2134 case BUILT_IN_MEMSET_CHK
:
2135 case BUILT_IN_STRNCPY_CHK
:
2139 case BUILT_IN_STRCPY_CHK
:
2140 case BUILT_IN_STPCPY_CHK
:
2144 case BUILT_IN_SNPRINTF_CHK
:
2145 case BUILT_IN_VSNPRINTF_CHK
:
2153 /* Try to use the dataflow information gathered by the CCP process. */
2154 visited
= BITMAP_ALLOC (NULL
);
2156 memset (val
, 0, sizeof (val
));
2157 for (i
= 0, a
= arglist
;
2159 i
++, arg_mask
>>= 1, a
= TREE_CHAIN (a
))
2162 bitmap_clear (visited
);
2163 if (!get_maxval_strlen (TREE_VALUE (a
), &val
[i
], visited
, type
))
2167 BITMAP_FREE (visited
);
2170 switch (DECL_FUNCTION_CODE (callee
))
2172 case BUILT_IN_STRLEN
:
2175 tree
new = fold_convert (TREE_TYPE (fn
), val
[0]);
2177 /* If the result is not a valid gimple value, or not a cast
2178 of a valid gimple value, then we can not use the result. */
2179 if (is_gimple_val (new)
2180 || (is_gimple_cast (new)
2181 && is_gimple_val (TREE_OPERAND (new, 0))))
2186 case BUILT_IN_STRCPY
:
2187 if (val
[1] && is_gimple_val (val
[1]))
2188 result
= fold_builtin_strcpy (callee
, arglist
, val
[1]);
2191 case BUILT_IN_STRNCPY
:
2192 if (val
[1] && is_gimple_val (val
[1]))
2193 result
= fold_builtin_strncpy (callee
, arglist
, val
[1]);
2196 case BUILT_IN_FPUTS
:
2197 result
= fold_builtin_fputs (arglist
,
2198 TREE_CODE (stmt
) != MODIFY_EXPR
, 0,
2202 case BUILT_IN_FPUTS_UNLOCKED
:
2203 result
= fold_builtin_fputs (arglist
,
2204 TREE_CODE (stmt
) != MODIFY_EXPR
, 1,
2208 case BUILT_IN_MEMCPY_CHK
:
2209 case BUILT_IN_MEMPCPY_CHK
:
2210 case BUILT_IN_MEMMOVE_CHK
:
2211 case BUILT_IN_MEMSET_CHK
:
2212 if (val
[2] && is_gimple_val (val
[2]))
2213 result
= fold_builtin_memory_chk (callee
, arglist
, val
[2], ignore
,
2214 DECL_FUNCTION_CODE (callee
));
2217 case BUILT_IN_STRCPY_CHK
:
2218 case BUILT_IN_STPCPY_CHK
:
2219 if (val
[1] && is_gimple_val (val
[1]))
2220 result
= fold_builtin_stxcpy_chk (callee
, arglist
, val
[1], ignore
,
2221 DECL_FUNCTION_CODE (callee
));
2224 case BUILT_IN_STRNCPY_CHK
:
2225 if (val
[2] && is_gimple_val (val
[2]))
2226 result
= fold_builtin_strncpy_chk (arglist
, val
[2]);
2229 case BUILT_IN_SNPRINTF_CHK
:
2230 case BUILT_IN_VSNPRINTF_CHK
:
2231 if (val
[1] && is_gimple_val (val
[1]))
2232 result
= fold_builtin_snprintf_chk (arglist
, val
[1],
2233 DECL_FUNCTION_CODE (callee
));
2240 if (result
&& ignore
)
2241 result
= fold_ignored_result (result
);
2246 /* Fold the statement pointed to by STMT_P. In some cases, this function may
2247 replace the whole statement with a new one. Returns true iff folding
2248 makes any changes. */
2251 fold_stmt (tree
*stmt_p
)
2253 tree rhs
, result
, stmt
;
2254 bool changed
= false;
2258 /* If we replaced constants and the statement makes pointer dereferences,
2259 then we may need to fold instances of *&VAR into VAR, etc. */
2260 if (walk_tree (stmt_p
, fold_stmt_r
, &changed
, NULL
))
2263 = build_function_call_expr (implicit_built_in_decls
[BUILT_IN_TRAP
],
2268 rhs
= get_rhs (stmt
);
2273 if (TREE_CODE (rhs
) == CALL_EXPR
)
2277 /* Check for builtins that CCP can handle using information not
2278 available in the generic fold routines. */
2279 callee
= get_callee_fndecl (rhs
);
2280 if (callee
&& DECL_BUILT_IN (callee
))
2281 result
= ccp_fold_builtin (stmt
, rhs
);
2284 /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve
2285 here are when we've propagated the address of a decl into the
2287 /* ??? Should perhaps do this in fold proper. However, doing it
2288 there requires that we create a new CALL_EXPR, and that requires
2289 copying EH region info to the new node. Easier to just do it
2290 here where we can just smash the call operand. */
2291 callee
= TREE_OPERAND (rhs
, 0);
2292 if (TREE_CODE (callee
) == OBJ_TYPE_REF
2293 && lang_hooks
.fold_obj_type_ref
2294 && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee
)) == ADDR_EXPR
2295 && DECL_P (TREE_OPERAND
2296 (OBJ_TYPE_REF_OBJECT (callee
), 0)))
2300 /* ??? Caution: Broken ADDR_EXPR semantics means that
2301 looking at the type of the operand of the addr_expr
2302 can yield an array type. See silly exception in
2303 check_pointer_types_r. */
2305 t
= TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee
)));
2306 t
= lang_hooks
.fold_obj_type_ref (callee
, t
);
2309 TREE_OPERAND (rhs
, 0) = t
;
2316 /* If we couldn't fold the RHS, hand over to the generic fold routines. */
2317 if (result
== NULL_TREE
)
2318 result
= fold (rhs
);
2320 /* Strip away useless type conversions. Both the NON_LVALUE_EXPR that
2321 may have been added by fold, and "useless" type conversions that might
2322 now be apparent due to propagation. */
2323 STRIP_USELESS_TYPE_CONVERSION (result
);
2326 changed
|= set_rhs (stmt_p
, result
);
2331 /* Perform the minimal folding on statement STMT. Only operations like
2332 *&x created by constant propagation are handled. The statement cannot
2333 be replaced with a new one. */
2336 fold_stmt_inplace (tree stmt
)
2338 tree old_stmt
= stmt
, rhs
, new_rhs
;
2339 bool changed
= false;
2341 walk_tree (&stmt
, fold_stmt_r
, &changed
, NULL
);
2342 gcc_assert (stmt
== old_stmt
);
2344 rhs
= get_rhs (stmt
);
2345 if (!rhs
|| rhs
== stmt
)
2348 new_rhs
= fold (rhs
);
2349 STRIP_USELESS_TYPE_CONVERSION (new_rhs
);
2353 changed
|= set_rhs (&stmt
, new_rhs
);
2354 gcc_assert (stmt
== old_stmt
);
2359 /* Convert EXPR into a GIMPLE value suitable for substitution on the
2360 RHS of an assignment. Insert the necessary statements before
2364 convert_to_gimple_builtin (block_stmt_iterator
*si_p
, tree expr
)
2366 tree_stmt_iterator ti
;
2367 tree stmt
= bsi_stmt (*si_p
);
2368 tree tmp
, stmts
= NULL
;
2370 push_gimplify_context ();
2371 tmp
= get_initialized_tmp_var (expr
, &stmts
, NULL
);
2372 pop_gimplify_context (NULL
);
2374 if (EXPR_HAS_LOCATION (stmt
))
2375 annotate_all_with_locus (&stmts
, EXPR_LOCATION (stmt
));
2377 /* The replacement can expose previously unreferenced variables. */
2378 for (ti
= tsi_start (stmts
); !tsi_end_p (ti
); tsi_next (&ti
))
2380 tree new_stmt
= tsi_stmt (ti
);
2381 find_new_referenced_vars (tsi_stmt_ptr (ti
));
2382 bsi_insert_before (si_p
, new_stmt
, BSI_NEW_STMT
);
2383 mark_new_vars_to_rename (bsi_stmt (*si_p
));
2391 /* A simple pass that attempts to fold all builtin functions. This pass
2392 is run after we've propagated as many constants as we can. */
2395 execute_fold_all_builtins (void)
2397 bool cfg_changed
= false;
2401 block_stmt_iterator i
;
2402 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
2404 tree
*stmtp
= bsi_stmt_ptr (i
);
2405 tree old_stmt
= *stmtp
;
2406 tree call
= get_rhs (*stmtp
);
2407 tree callee
, result
;
2408 enum built_in_function fcode
;
2410 if (!call
|| TREE_CODE (call
) != CALL_EXPR
)
2415 callee
= get_callee_fndecl (call
);
2416 if (!callee
|| DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
)
2421 fcode
= DECL_FUNCTION_CODE (callee
);
2423 result
= ccp_fold_builtin (*stmtp
, call
);
2425 switch (DECL_FUNCTION_CODE (callee
))
2427 case BUILT_IN_CONSTANT_P
:
2428 /* Resolve __builtin_constant_p. If it hasn't been
2429 folded to integer_one_node by now, it's fairly
2430 certain that the value simply isn't constant. */
2431 result
= integer_zero_node
;
2439 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2441 fprintf (dump_file
, "Simplified\n ");
2442 print_generic_stmt (dump_file
, *stmtp
, dump_flags
);
2445 if (!set_rhs (stmtp
, result
))
2447 result
= convert_to_gimple_builtin (&i
, result
);
2450 bool ok
= set_rhs (stmtp
, result
);
2455 update_stmt (*stmtp
);
2456 if (maybe_clean_or_replace_eh_stmt (old_stmt
, *stmtp
)
2457 && tree_purge_dead_eh_edges (bb
))
2460 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2462 fprintf (dump_file
, "to\n ");
2463 print_generic_stmt (dump_file
, *stmtp
, dump_flags
);
2464 fprintf (dump_file
, "\n");
2467 /* Retry the same statement if it changed into another
2468 builtin, there might be new opportunities now. */
2469 call
= get_rhs (*stmtp
);
2470 if (!call
|| TREE_CODE (call
) != CALL_EXPR
)
2475 callee
= get_callee_fndecl (call
);
2477 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2478 || DECL_FUNCTION_CODE (callee
) == fcode
)
2483 /* Delete unreachable blocks. */
2485 cleanup_tree_cfg ();
2489 struct tree_opt_pass pass_fold_builtins
=
2493 execute_fold_all_builtins
, /* execute */
2496 0, /* static_pass_number */
2498 PROP_cfg
| PROP_ssa
| PROP_alias
, /* properties_required */
2499 0, /* properties_provided */
2500 0, /* properties_destroyed */
2501 0, /* todo_flags_start */
2504 | TODO_update_ssa
, /* todo_flags_finish */