1 /* Conditional constant propagation pass for the GNU compiler.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006
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 -> the initial state of the value. This value
33 is replaced with a correct initial value
34 the first time the value is used, so the
35 rest of the pass does not need to care about
36 it. Using this value simplifies initialization
37 of the pass, and prevents us from needlessly
38 scanning statements that are never reached.
40 UNDEFINED -> V_i is a local variable whose definition
41 has not been processed yet. Therefore we
42 don't yet know if its value is a constant
45 CONSTANT -> V_i has been found to hold a constant
48 VARYING -> V_i cannot take a constant value, or if it
49 does, it is not possible to determine it
52 The core of SSA-CCP is in ccp_visit_stmt and ccp_visit_phi_node:
54 1- In ccp_visit_stmt, we are interested in assignments whose RHS
55 evaluates into a constant and conditional jumps whose predicate
56 evaluates into a boolean true or false. When an assignment of
57 the form V_i = CONST is found, V_i's lattice value is set to
58 CONSTANT and CONST is associated with it. This causes the
59 propagation engine to add all the SSA edges coming out the
60 assignment into the worklists, so that statements that use V_i
63 If the statement is a conditional with a constant predicate, we
64 mark the outgoing edges as executable or not executable
65 depending on the predicate's value. This is then used when
66 visiting PHI nodes to know when a PHI argument can be ignored.
69 2- In ccp_visit_phi_node, if all the PHI arguments evaluate to the
70 same constant C, then the LHS of the PHI is set to C. This
71 evaluation is known as the "meet operation". Since one of the
72 goals of this evaluation is to optimistically return constant
73 values as often as possible, it uses two main short cuts:
75 - If an argument is flowing in through a non-executable edge, it
76 is ignored. This is useful in cases like this:
82 a_11 = PHI (a_9, a_10)
84 If PRED is known to always evaluate to false, then we can
85 assume that a_11 will always take its value from a_10, meaning
86 that instead of consider it VARYING (a_9 and a_10 have
87 different values), we can consider it CONSTANT 100.
89 - If an argument has an UNDEFINED value, then it does not affect
90 the outcome of the meet operation. If a variable V_i has an
91 UNDEFINED value, it means that either its defining statement
92 hasn't been visited yet or V_i has no defining statement, in
93 which case the original symbol 'V' is being used
94 uninitialized. Since 'V' is a local variable, the compiler
95 may assume any initial value for it.
98 After propagation, every variable V_i that ends up with a lattice
99 value of CONSTANT will have the associated constant value in the
100 array CONST_VAL[i].VALUE. That is fed into substitute_and_fold for
101 final substitution and folding.
104 Constant propagation in stores and loads (STORE-CCP)
105 ----------------------------------------------------
107 While CCP has all the logic to propagate constants in GIMPLE
108 registers, it is missing the ability to associate constants with
109 stores and loads (i.e., pointer dereferences, structures and
110 global/aliased variables). We don't keep loads and stores in
111 SSA, but we do build a factored use-def web for them (in the
114 For instance, consider the following code fragment:
133 We should be able to deduce that the predicate 'a.a != B' is always
134 false. To achieve this, we associate constant values to the SSA
135 names in the V_MAY_DEF and V_MUST_DEF operands for each store.
136 Additionally, since we also glob partial loads/stores with the base
137 symbol, we also keep track of the memory reference where the
138 constant value was stored (in the MEM_REF field of PROP_VALUE_T).
141 # a_5 = V_MAY_DEF <a_4>
147 In the example above, CCP will associate value '2' with 'a_5', but
148 it would be wrong to replace the load from 'a.b' with '2', because
149 '2' had been stored into a.a.
151 Note that the initial value of virtual operands is VARYING, not
152 UNDEFINED. Consider, for instance global variables:
160 # A_5 = PHI (A_4, A_2);
168 The value of A_2 cannot be assumed to be UNDEFINED, as it may have
169 been defined outside of foo. If we were to assume it UNDEFINED, we
170 would erroneously optimize the above into 'return 3;'.
172 Though STORE-CCP is not too expensive, it does have to do more work
173 than regular CCP, so it is only enabled at -O2. Both regular CCP
174 and STORE-CCP use the exact same algorithm. The only distinction
175 is that when doing STORE-CCP, the boolean variable DO_STORE_CCP is
176 set to true. This affects the evaluation of statements and PHI
181 Constant propagation with conditional branches,
182 Wegman and Zadeck, ACM TOPLAS 13(2):181-210.
184 Building an Optimizing Compiler,
185 Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9.
187 Advanced Compiler Design and Implementation,
188 Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */
192 #include "coretypes.h"
199 #include "basic-block.h"
202 #include "function.h"
203 #include "diagnostic.h"
205 #include "tree-dump.h"
206 #include "tree-flow.h"
207 #include "tree-pass.h"
208 #include "tree-ssa-propagate.h"
209 #include "langhooks.h"
213 /* Possible lattice values. */
222 /* Array of propagated constant values. After propagation,
223 CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If
224 the constant is held in an SSA name representing a memory store
225 (i.e., a V_MAY_DEF or V_MUST_DEF), CONST_VAL[I].MEM_REF will
226 contain the actual memory reference used to store (i.e., the LHS of
227 the assignment doing the store). */
228 static prop_value_t
*const_val
;
230 /* True if we are also propagating constants in stores and loads. */
231 static bool do_store_ccp
;
233 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */
236 dump_lattice_value (FILE *outf
, const char *prefix
, prop_value_t val
)
238 switch (val
.lattice_val
)
241 fprintf (outf
, "%sUNINITIALIZED", prefix
);
244 fprintf (outf
, "%sUNDEFINED", prefix
);
247 fprintf (outf
, "%sVARYING", prefix
);
250 fprintf (outf
, "%sCONSTANT ", prefix
);
251 print_generic_expr (outf
, val
.value
, dump_flags
);
259 /* Print lattice value VAL to stderr. */
261 void debug_lattice_value (prop_value_t val
);
264 debug_lattice_value (prop_value_t val
)
266 dump_lattice_value (stderr
, "", val
);
267 fprintf (stderr
, "\n");
271 /* The regular is_gimple_min_invariant does a shallow test of the object.
272 It assumes that full gimplification has happened, or will happen on the
273 object. For a value coming from DECL_INITIAL, this is not true, so we
274 have to be more strict ourselves. */
277 ccp_decl_initial_min_invariant (tree t
)
279 if (!is_gimple_min_invariant (t
))
281 if (TREE_CODE (t
) == ADDR_EXPR
)
283 /* Inline and unroll is_gimple_addressable. */
286 t
= TREE_OPERAND (t
, 0);
287 if (is_gimple_id (t
))
289 if (!handled_component_p (t
))
296 /* If SYM is a constant variable with known value, return the value.
297 NULL_TREE is returned otherwise. */
300 get_symbol_constant_value (tree sym
)
302 if (TREE_STATIC (sym
)
303 && TREE_READONLY (sym
)
306 tree val
= DECL_INITIAL (sym
);
308 && ccp_decl_initial_min_invariant (val
))
315 /* Compute a default value for variable VAR and store it in the
316 CONST_VAL array. The following rules are used to get default
319 1- Global and static variables that are declared constant are
322 2- Any other value is considered UNDEFINED. This is useful when
323 considering PHI nodes. PHI arguments that are undefined do not
324 change the constant value of the PHI node, which allows for more
325 constants to be propagated.
327 3- If SSA_NAME_VALUE is set and it is a constant, its value is
330 4- Variables defined by statements other than assignments and PHI
331 nodes are considered VARYING.
333 5- Initial values of variables that are not GIMPLE registers are
334 considered VARYING. */
337 get_default_value (tree var
)
339 tree sym
= SSA_NAME_VAR (var
);
340 prop_value_t val
= { UNINITIALIZED
, NULL_TREE
, NULL_TREE
};
343 if (!do_store_ccp
&& !is_gimple_reg (var
))
345 /* Short circuit for regular CCP. We are not interested in any
346 non-register when DO_STORE_CCP is false. */
347 val
.lattice_val
= VARYING
;
349 else if (SSA_NAME_VALUE (var
)
350 && is_gimple_min_invariant (SSA_NAME_VALUE (var
)))
352 val
.lattice_val
= CONSTANT
;
353 val
.value
= SSA_NAME_VALUE (var
);
355 else if ((cst_val
= get_symbol_constant_value (sym
)) != NULL_TREE
)
357 /* Globals and static variables declared 'const' take their
359 val
.lattice_val
= CONSTANT
;
365 tree stmt
= SSA_NAME_DEF_STMT (var
);
367 if (IS_EMPTY_STMT (stmt
))
369 /* Variables defined by an empty statement are those used
370 before being initialized. If VAR is a local variable, we
371 can assume initially that it is UNDEFINED, otherwise we must
372 consider it VARYING. */
373 if (is_gimple_reg (sym
) && TREE_CODE (sym
) != PARM_DECL
)
374 val
.lattice_val
= UNDEFINED
;
376 val
.lattice_val
= VARYING
;
378 else if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
379 || TREE_CODE (stmt
) == PHI_NODE
)
381 /* Any other variable defined by an assignment or a PHI node
382 is considered UNDEFINED. */
383 val
.lattice_val
= UNDEFINED
;
387 /* Otherwise, VAR will never take on a constant value. */
388 val
.lattice_val
= VARYING
;
396 /* Get the constant value associated with variable VAR. */
398 static inline prop_value_t
*
401 prop_value_t
*val
= &const_val
[SSA_NAME_VERSION (var
)];
403 if (val
->lattice_val
== UNINITIALIZED
)
404 *val
= get_default_value (var
);
409 /* Sets the value associated with VAR to VARYING. */
412 set_value_varying (tree var
)
414 prop_value_t
*val
= &const_val
[SSA_NAME_VERSION (var
)];
416 val
->lattice_val
= VARYING
;
417 val
->value
= NULL_TREE
;
418 val
->mem_ref
= NULL_TREE
;
421 /* For float types, modify the value of VAL to make ccp work correctly
422 for non-standard values (-0, NaN):
424 If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0.
425 If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED.
426 This is to fix the following problem (see PR 29921): Suppose we have
430 and we set value of y to NaN. This causes value of x to be set to NaN.
431 When we later determine that y is in fact VARYING, fold uses the fact
432 that HONOR_NANS is false, and we try to change the value of x to 0,
433 causing an ICE. With HONOR_NANS being false, the real appearance of
434 NaN would cause undefined behavior, though, so claiming that y (and x)
435 are UNDEFINED initially is correct. */
438 canonicalize_float_value (prop_value_t
*val
)
440 enum machine_mode mode
;
444 if (val
->lattice_val
!= CONSTANT
445 || TREE_CODE (val
->value
) != REAL_CST
)
448 d
= TREE_REAL_CST (val
->value
);
449 type
= TREE_TYPE (val
->value
);
450 mode
= TYPE_MODE (type
);
452 if (!HONOR_SIGNED_ZEROS (mode
)
453 && REAL_VALUE_MINUS_ZERO (d
))
455 val
->value
= build_real (type
, dconst0
);
459 if (!HONOR_NANS (mode
)
460 && REAL_VALUE_ISNAN (d
))
462 val
->lattice_val
= UNDEFINED
;
469 /* Set the value for variable VAR to NEW_VAL. Return true if the new
470 value is different from VAR's previous value. */
473 set_lattice_value (tree var
, prop_value_t new_val
)
475 prop_value_t
*old_val
= get_value (var
);
477 canonicalize_float_value (&new_val
);
479 /* Lattice transitions must always be monotonically increasing in
480 value. If *OLD_VAL and NEW_VAL are the same, return false to
481 inform the caller that this was a non-transition. */
483 gcc_assert (old_val
->lattice_val
< new_val
.lattice_val
484 || (old_val
->lattice_val
== new_val
.lattice_val
485 && ((!old_val
->value
&& !new_val
.value
)
486 || operand_equal_p (old_val
->value
, new_val
.value
, 0))
487 && old_val
->mem_ref
== new_val
.mem_ref
));
489 if (old_val
->lattice_val
!= new_val
.lattice_val
)
491 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
493 dump_lattice_value (dump_file
, "Lattice value changed to ", new_val
);
494 fprintf (dump_file
, ". Adding SSA edges to worklist.\n");
499 gcc_assert (new_val
.lattice_val
!= UNDEFINED
);
507 /* Return the likely CCP lattice value for STMT.
509 If STMT has no operands, then return CONSTANT.
511 Else if any operands of STMT are undefined, then return UNDEFINED.
513 Else if any operands of STMT are constants, then return CONSTANT.
515 Else return VARYING. */
518 likely_value (tree stmt
)
520 bool has_constant_operand
;
525 ann
= stmt_ann (stmt
);
527 /* If the statement has volatile operands, it won't fold to a
529 if (ann
->has_volatile_ops
)
532 /* If we are not doing store-ccp, statements with loads
533 and/or stores will never fold into a constant. */
535 && !ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
539 /* A CALL_EXPR is assumed to be varying. NOTE: This may be overly
540 conservative, in the presence of const and pure calls. */
541 if (get_call_expr_in (stmt
) != NULL_TREE
)
544 /* Anything other than assignments and conditional jumps are not
545 interesting for CCP. */
546 if (TREE_CODE (stmt
) != GIMPLE_MODIFY_STMT
547 && !(TREE_CODE (stmt
) == RETURN_EXPR
&& get_rhs (stmt
) != NULL_TREE
)
548 && TREE_CODE (stmt
) != COND_EXPR
549 && TREE_CODE (stmt
) != SWITCH_EXPR
)
552 if (is_gimple_min_invariant (get_rhs (stmt
)))
555 has_constant_operand
= false;
556 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, iter
, SSA_OP_USE
| SSA_OP_VUSE
)
558 prop_value_t
*val
= get_value (use
);
560 if (val
->lattice_val
== UNDEFINED
)
563 if (val
->lattice_val
== CONSTANT
)
564 has_constant_operand
= true;
567 if (has_constant_operand
568 /* We do not consider virtual operands here -- load from read-only
569 memory may have only VARYING virtual operands, but still be
571 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_USE
))
577 /* Returns true if STMT cannot be constant. */
580 surely_varying_stmt_p (tree stmt
)
582 /* If the statement has operands that we cannot handle, it cannot be
584 if (stmt_ann (stmt
)->has_volatile_ops
)
587 if (!ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
592 /* We can only handle simple loads and stores. */
593 if (!stmt_makes_single_load (stmt
)
594 && !stmt_makes_single_store (stmt
))
598 /* If it contains a call, it is varying. */
599 if (get_call_expr_in (stmt
) != NULL_TREE
)
602 /* Anything other than assignments and conditional jumps are not
603 interesting for CCP. */
604 if (TREE_CODE (stmt
) != GIMPLE_MODIFY_STMT
605 && !(TREE_CODE (stmt
) == RETURN_EXPR
&& get_rhs (stmt
) != NULL_TREE
)
606 && TREE_CODE (stmt
) != COND_EXPR
607 && TREE_CODE (stmt
) != SWITCH_EXPR
)
613 /* Initialize local data structures for CCP. */
616 ccp_initialize (void)
620 const_val
= XCNEWVEC (prop_value_t
, num_ssa_names
);
622 /* Initialize simulation flags for PHI nodes and statements. */
625 block_stmt_iterator i
;
627 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
629 tree stmt
= bsi_stmt (i
);
630 bool is_varying
= surely_varying_stmt_p (stmt
);
637 /* If the statement will not produce a constant, mark
638 all its outputs VARYING. */
639 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
642 set_value_varying (def
);
646 DONT_SIMULATE_AGAIN (stmt
) = is_varying
;
650 /* Now process PHI nodes. We never set DONT_SIMULATE_AGAIN on phi node,
651 since we do not know which edges are executable yet, except for
652 phi nodes for virtual operands when we do not do store ccp. */
657 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
659 if (!do_store_ccp
&& !is_gimple_reg (PHI_RESULT (phi
)))
660 DONT_SIMULATE_AGAIN (phi
) = true;
662 DONT_SIMULATE_AGAIN (phi
) = false;
668 /* Do final substitution of propagated values, cleanup the flowgraph and
669 free allocated storage. */
674 /* Perform substitutions based on the known constant values. */
675 substitute_and_fold (const_val
, false);
681 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
684 any M UNDEFINED = any
685 any M VARYING = VARYING
686 Ci M Cj = Ci if (i == j)
687 Ci M Cj = VARYING if (i != j)
691 ccp_lattice_meet (prop_value_t
*val1
, prop_value_t
*val2
)
693 if (val1
->lattice_val
== UNDEFINED
)
695 /* UNDEFINED M any = any */
698 else if (val2
->lattice_val
== UNDEFINED
)
700 /* any M UNDEFINED = any
701 Nothing to do. VAL1 already contains the value we want. */
704 else if (val1
->lattice_val
== VARYING
705 || val2
->lattice_val
== VARYING
)
707 /* any M VARYING = VARYING. */
708 val1
->lattice_val
= VARYING
;
709 val1
->value
= NULL_TREE
;
710 val1
->mem_ref
= NULL_TREE
;
712 else if (val1
->lattice_val
== CONSTANT
713 && val2
->lattice_val
== CONSTANT
714 && simple_cst_equal (val1
->value
, val2
->value
) == 1
716 || (val1
->mem_ref
&& val2
->mem_ref
717 && operand_equal_p (val1
->mem_ref
, val2
->mem_ref
, 0))))
719 /* Ci M Cj = Ci if (i == j)
720 Ci M Cj = VARYING if (i != j)
722 If these two values come from memory stores, make sure that
723 they come from the same memory reference. */
724 val1
->lattice_val
= CONSTANT
;
725 val1
->value
= val1
->value
;
726 val1
->mem_ref
= val1
->mem_ref
;
730 /* Any other combination is VARYING. */
731 val1
->lattice_val
= VARYING
;
732 val1
->value
= NULL_TREE
;
733 val1
->mem_ref
= NULL_TREE
;
738 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
739 lattice values to determine PHI_NODE's lattice value. The value of a
740 PHI node is determined calling ccp_lattice_meet with all the arguments
741 of the PHI node that are incoming via executable edges. */
743 static enum ssa_prop_result
744 ccp_visit_phi_node (tree phi
)
747 prop_value_t
*old_val
, new_val
;
749 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
751 fprintf (dump_file
, "\nVisiting PHI node: ");
752 print_generic_expr (dump_file
, phi
, dump_flags
);
755 old_val
= get_value (PHI_RESULT (phi
));
756 switch (old_val
->lattice_val
)
759 return SSA_PROP_VARYING
;
766 new_val
.lattice_val
= UNDEFINED
;
767 new_val
.value
= NULL_TREE
;
768 new_val
.mem_ref
= NULL_TREE
;
775 for (i
= 0; i
< PHI_NUM_ARGS (phi
); i
++)
777 /* Compute the meet operator over all the PHI arguments flowing
778 through executable edges. */
779 edge e
= PHI_ARG_EDGE (phi
, i
);
781 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
784 "\n Argument #%d (%d -> %d %sexecutable)\n",
785 i
, e
->src
->index
, e
->dest
->index
,
786 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
789 /* If the incoming edge is executable, Compute the meet operator for
790 the existing value of the PHI node and the current PHI argument. */
791 if (e
->flags
& EDGE_EXECUTABLE
)
793 tree arg
= PHI_ARG_DEF (phi
, i
);
794 prop_value_t arg_val
;
796 if (is_gimple_min_invariant (arg
))
798 arg_val
.lattice_val
= CONSTANT
;
800 arg_val
.mem_ref
= NULL_TREE
;
803 arg_val
= *(get_value (arg
));
805 ccp_lattice_meet (&new_val
, &arg_val
);
807 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
809 fprintf (dump_file
, "\t");
810 print_generic_expr (dump_file
, arg
, dump_flags
);
811 dump_lattice_value (dump_file
, "\tValue: ", arg_val
);
812 fprintf (dump_file
, "\n");
815 if (new_val
.lattice_val
== VARYING
)
820 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
822 dump_lattice_value (dump_file
, "\n PHI node value: ", new_val
);
823 fprintf (dump_file
, "\n\n");
826 /* Make the transition to the new value. */
827 if (set_lattice_value (PHI_RESULT (phi
), new_val
))
829 if (new_val
.lattice_val
== VARYING
)
830 return SSA_PROP_VARYING
;
832 return SSA_PROP_INTERESTING
;
835 return SSA_PROP_NOT_INTERESTING
;
839 /* CCP specific front-end to the non-destructive constant folding
842 Attempt to simplify the RHS of STMT knowing that one or more
843 operands are constants.
845 If simplification is possible, return the simplified RHS,
846 otherwise return the original RHS. */
851 tree rhs
= get_rhs (stmt
);
852 enum tree_code code
= TREE_CODE (rhs
);
853 enum tree_code_class kind
= TREE_CODE_CLASS (code
);
854 tree retval
= NULL_TREE
;
856 if (TREE_CODE (rhs
) == SSA_NAME
)
858 /* If the RHS is an SSA_NAME, return its known constant value,
860 return get_value (rhs
)->value
;
862 else if (do_store_ccp
&& stmt_makes_single_load (stmt
))
864 /* If the RHS is a memory load, see if the VUSEs associated with
865 it are a valid constant for that memory load. */
866 prop_value_t
*val
= get_value_loaded_by (stmt
, const_val
);
867 if (val
&& val
->mem_ref
)
869 if (operand_equal_p (val
->mem_ref
, rhs
, 0))
872 /* If RHS is extracting REALPART_EXPR or IMAGPART_EXPR of a
873 complex type with a known constant value, return it. */
874 if ((TREE_CODE (rhs
) == REALPART_EXPR
875 || TREE_CODE (rhs
) == IMAGPART_EXPR
)
876 && operand_equal_p (val
->mem_ref
, TREE_OPERAND (rhs
, 0), 0))
877 return fold_build1 (TREE_CODE (rhs
), TREE_TYPE (rhs
), val
->value
);
882 /* Unary operators. Note that we know the single operand must
883 be a constant. So this should almost always return a
885 if (kind
== tcc_unary
)
887 /* Handle unary operators which can appear in GIMPLE form. */
888 tree op0
= TREE_OPERAND (rhs
, 0);
890 /* Simplify the operand down to a constant. */
891 if (TREE_CODE (op0
) == SSA_NAME
)
893 prop_value_t
*val
= get_value (op0
);
894 if (val
->lattice_val
== CONSTANT
)
895 op0
= get_value (op0
)->value
;
898 if ((code
== NOP_EXPR
|| code
== CONVERT_EXPR
)
899 && tree_ssa_useless_type_conversion_1 (TREE_TYPE (rhs
),
902 return fold_unary (code
, TREE_TYPE (rhs
), op0
);
905 /* Binary and comparison operators. We know one or both of the
906 operands are constants. */
907 else if (kind
== tcc_binary
908 || kind
== tcc_comparison
909 || code
== TRUTH_AND_EXPR
910 || code
== TRUTH_OR_EXPR
911 || code
== TRUTH_XOR_EXPR
)
913 /* Handle binary and comparison operators that can appear in
915 tree op0
= TREE_OPERAND (rhs
, 0);
916 tree op1
= TREE_OPERAND (rhs
, 1);
918 /* Simplify the operands down to constants when appropriate. */
919 if (TREE_CODE (op0
) == SSA_NAME
)
921 prop_value_t
*val
= get_value (op0
);
922 if (val
->lattice_val
== CONSTANT
)
926 if (TREE_CODE (op1
) == SSA_NAME
)
928 prop_value_t
*val
= get_value (op1
);
929 if (val
->lattice_val
== CONSTANT
)
933 return fold_binary (code
, TREE_TYPE (rhs
), op0
, op1
);
936 /* We may be able to fold away calls to builtin functions if their
937 arguments are constants. */
938 else if (code
== CALL_EXPR
939 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == ADDR_EXPR
940 && (TREE_CODE (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0))
942 && DECL_BUILT_IN (TREE_OPERAND (TREE_OPERAND (rhs
, 0), 0)))
944 if (!ZERO_SSA_OPERANDS (stmt
, SSA_OP_USE
))
947 tree fndecl
, arglist
;
952 /* Preserve the original values of every operand. */
953 orig
= XNEWVEC (tree
, NUM_SSA_OPERANDS (stmt
, SSA_OP_USE
));
954 FOR_EACH_SSA_TREE_OPERAND (var
, stmt
, iter
, SSA_OP_USE
)
957 /* Substitute operands with their values and try to fold. */
958 replace_uses_in (stmt
, NULL
, const_val
);
959 fndecl
= get_callee_fndecl (rhs
);
960 arglist
= TREE_OPERAND (rhs
, 1);
961 retval
= fold_builtin (fndecl
, arglist
, false);
963 /* Restore operands to their original form. */
965 FOR_EACH_SSA_USE_OPERAND (var_p
, stmt
, iter
, SSA_OP_USE
)
966 SET_USE (var_p
, orig
[i
++]);
973 /* If we got a simplified form, see if we need to convert its type. */
975 return fold_convert (TREE_TYPE (rhs
), retval
);
977 /* No simplification was possible. */
982 /* Return the tree representing the element referenced by T if T is an
983 ARRAY_REF or COMPONENT_REF into constant aggregates. Return
984 NULL_TREE otherwise. */
987 fold_const_aggregate_ref (tree t
)
990 tree base
, ctor
, idx
, field
;
991 unsigned HOST_WIDE_INT cnt
;
994 switch (TREE_CODE (t
))
997 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
998 DECL_INITIAL. If BASE is a nested reference into another
999 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1000 the inner reference. */
1001 base
= TREE_OPERAND (t
, 0);
1002 switch (TREE_CODE (base
))
1005 if (!TREE_READONLY (base
)
1006 || TREE_CODE (TREE_TYPE (base
)) != ARRAY_TYPE
1007 || !targetm
.binds_local_p (base
))
1010 ctor
= DECL_INITIAL (base
);
1015 ctor
= fold_const_aggregate_ref (base
);
1022 if (ctor
== NULL_TREE
1023 || (TREE_CODE (ctor
) != CONSTRUCTOR
1024 && TREE_CODE (ctor
) != STRING_CST
)
1025 || !TREE_STATIC (ctor
))
1028 /* Get the index. If we have an SSA_NAME, try to resolve it
1029 with the current lattice value for the SSA_NAME. */
1030 idx
= TREE_OPERAND (t
, 1);
1031 switch (TREE_CODE (idx
))
1034 if ((value
= get_value (idx
))
1035 && value
->lattice_val
== CONSTANT
1036 && TREE_CODE (value
->value
) == INTEGER_CST
)
1049 /* Fold read from constant string. */
1050 if (TREE_CODE (ctor
) == STRING_CST
)
1052 if ((TYPE_MODE (TREE_TYPE (t
))
1053 == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor
))))
1054 && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor
))))
1056 && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor
)))) == 1
1057 && compare_tree_int (idx
, TREE_STRING_LENGTH (ctor
)) < 0)
1058 return build_int_cst (TREE_TYPE (t
), (TREE_STRING_POINTER (ctor
)
1059 [TREE_INT_CST_LOW (idx
)]));
1063 /* Whoo-hoo! I'll fold ya baby. Yeah! */
1064 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor
), cnt
, cfield
, cval
)
1065 if (tree_int_cst_equal (cfield
, idx
))
1070 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1071 DECL_INITIAL. If BASE is a nested reference into another
1072 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1073 the inner reference. */
1074 base
= TREE_OPERAND (t
, 0);
1075 switch (TREE_CODE (base
))
1078 if (!TREE_READONLY (base
)
1079 || TREE_CODE (TREE_TYPE (base
)) != RECORD_TYPE
1080 || !targetm
.binds_local_p (base
))
1083 ctor
= DECL_INITIAL (base
);
1088 ctor
= fold_const_aggregate_ref (base
);
1095 if (ctor
== NULL_TREE
1096 || TREE_CODE (ctor
) != CONSTRUCTOR
1097 || !TREE_STATIC (ctor
))
1100 field
= TREE_OPERAND (t
, 1);
1102 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor
), cnt
, cfield
, cval
)
1104 /* FIXME: Handle bit-fields. */
1105 && ! DECL_BIT_FIELD (cfield
))
1112 tree c
= fold_const_aggregate_ref (TREE_OPERAND (t
, 0));
1113 if (c
&& TREE_CODE (c
) == COMPLEX_CST
)
1114 return fold_build1 (TREE_CODE (t
), TREE_TYPE (t
), c
);
1125 /* Evaluate statement STMT. */
1128 evaluate_stmt (tree stmt
)
1131 tree simplified
= NULL_TREE
;
1132 ccp_lattice_t likelyvalue
= likely_value (stmt
);
1134 val
.mem_ref
= NULL_TREE
;
1136 /* If the statement is likely to have a CONSTANT result, then try
1137 to fold the statement to determine the constant value. */
1138 if (likelyvalue
== CONSTANT
)
1139 simplified
= ccp_fold (stmt
);
1140 /* If the statement is likely to have a VARYING result, then do not
1141 bother folding the statement. */
1142 if (likelyvalue
== VARYING
)
1143 simplified
= get_rhs (stmt
);
1144 /* If the statement is an ARRAY_REF or COMPONENT_REF into constant
1145 aggregates, extract the referenced constant. Otherwise the
1146 statement is likely to have an UNDEFINED value, and there will be
1147 nothing to do. Note that fold_const_aggregate_ref returns
1148 NULL_TREE if the first case does not match. */
1149 else if (!simplified
)
1150 simplified
= fold_const_aggregate_ref (get_rhs (stmt
));
1152 if (simplified
&& is_gimple_min_invariant (simplified
))
1154 /* The statement produced a constant value. */
1155 val
.lattice_val
= CONSTANT
;
1156 val
.value
= simplified
;
1160 /* The statement produced a nonconstant value. If the statement
1161 had UNDEFINED operands, then the result of the statement
1162 should be UNDEFINED. Otherwise, the statement is VARYING. */
1163 if (likelyvalue
== UNDEFINED
)
1164 val
.lattice_val
= likelyvalue
;
1166 val
.lattice_val
= VARYING
;
1168 val
.value
= NULL_TREE
;
1175 /* Visit the assignment statement STMT. Set the value of its LHS to the
1176 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
1177 creates virtual definitions, set the value of each new name to that
1178 of the RHS (if we can derive a constant out of the RHS). */
1180 static enum ssa_prop_result
1181 visit_assignment (tree stmt
, tree
*output_p
)
1185 enum ssa_prop_result retval
;
1187 lhs
= GIMPLE_STMT_OPERAND (stmt
, 0);
1188 rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
1190 if (TREE_CODE (rhs
) == SSA_NAME
)
1192 /* For a simple copy operation, we copy the lattice values. */
1193 prop_value_t
*nval
= get_value (rhs
);
1196 else if (do_store_ccp
&& stmt_makes_single_load (stmt
))
1198 /* Same as above, but the RHS is not a gimple register and yet
1199 has a known VUSE. If STMT is loading from the same memory
1200 location that created the SSA_NAMEs for the virtual operands,
1201 we can propagate the value on the RHS. */
1202 prop_value_t
*nval
= get_value_loaded_by (stmt
, const_val
);
1206 && operand_equal_p (nval
->mem_ref
, rhs
, 0))
1209 val
= evaluate_stmt (stmt
);
1212 /* Evaluate the statement. */
1213 val
= evaluate_stmt (stmt
);
1215 /* If the original LHS was a VIEW_CONVERT_EXPR, modify the constant
1216 value to be a VIEW_CONVERT_EXPR of the old constant value.
1218 ??? Also, if this was a definition of a bitfield, we need to widen
1219 the constant value into the type of the destination variable. This
1220 should not be necessary if GCC represented bitfields properly. */
1222 tree orig_lhs
= GIMPLE_STMT_OPERAND (stmt
, 0);
1224 if (TREE_CODE (orig_lhs
) == VIEW_CONVERT_EXPR
1225 && val
.lattice_val
== CONSTANT
)
1227 tree w
= fold_unary (VIEW_CONVERT_EXPR
,
1228 TREE_TYPE (TREE_OPERAND (orig_lhs
, 0)),
1231 orig_lhs
= TREE_OPERAND (orig_lhs
, 0);
1232 if (w
&& is_gimple_min_invariant (w
))
1236 val
.lattice_val
= VARYING
;
1241 if (val
.lattice_val
== CONSTANT
1242 && TREE_CODE (orig_lhs
) == COMPONENT_REF
1243 && DECL_BIT_FIELD (TREE_OPERAND (orig_lhs
, 1)))
1245 tree w
= widen_bitfield (val
.value
, TREE_OPERAND (orig_lhs
, 1),
1248 if (w
&& is_gimple_min_invariant (w
))
1252 val
.lattice_val
= VARYING
;
1253 val
.value
= NULL_TREE
;
1254 val
.mem_ref
= NULL_TREE
;
1259 retval
= SSA_PROP_NOT_INTERESTING
;
1261 /* Set the lattice value of the statement's output. */
1262 if (TREE_CODE (lhs
) == SSA_NAME
)
1264 /* If STMT is an assignment to an SSA_NAME, we only have one
1266 if (set_lattice_value (lhs
, val
))
1269 if (val
.lattice_val
== VARYING
)
1270 retval
= SSA_PROP_VARYING
;
1272 retval
= SSA_PROP_INTERESTING
;
1275 else if (do_store_ccp
&& stmt_makes_single_store (stmt
))
1277 /* Otherwise, set the names in V_MAY_DEF/V_MUST_DEF operands
1278 to the new constant value and mark the LHS as the memory
1279 reference associated with VAL. */
1284 /* Mark VAL as stored in the LHS of this assignment. */
1285 if (val
.lattice_val
== CONSTANT
)
1288 /* Set the value of every VDEF to VAL. */
1290 FOR_EACH_SSA_TREE_OPERAND (vdef
, stmt
, i
, SSA_OP_VIRTUAL_DEFS
)
1292 /* See PR 29801. We may have VDEFs for read-only variables
1293 (see the handling of unmodifiable variables in
1294 add_virtual_operand); do not attempt to change their value. */
1295 if (get_symbol_constant_value (SSA_NAME_VAR (vdef
)) != NULL_TREE
)
1298 changed
|= set_lattice_value (vdef
, val
);
1301 /* Note that for propagation purposes, we are only interested in
1302 visiting statements that load the exact same memory reference
1303 stored here. Those statements will have the exact same list
1304 of virtual uses, so it is enough to set the output of this
1305 statement to be its first virtual definition. */
1306 *output_p
= first_vdef (stmt
);
1309 if (val
.lattice_val
== VARYING
)
1310 retval
= SSA_PROP_VARYING
;
1312 retval
= SSA_PROP_INTERESTING
;
1320 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
1321 if it can determine which edge will be taken. Otherwise, return
1322 SSA_PROP_VARYING. */
1324 static enum ssa_prop_result
1325 visit_cond_stmt (tree stmt
, edge
*taken_edge_p
)
1330 block
= bb_for_stmt (stmt
);
1331 val
= evaluate_stmt (stmt
);
1333 /* Find which edge out of the conditional block will be taken and add it
1334 to the worklist. If no single edge can be determined statically,
1335 return SSA_PROP_VARYING to feed all the outgoing edges to the
1336 propagation engine. */
1337 *taken_edge_p
= val
.value
? find_taken_edge (block
, val
.value
) : 0;
1339 return SSA_PROP_INTERESTING
;
1341 return SSA_PROP_VARYING
;
1345 /* Evaluate statement STMT. If the statement produces an output value and
1346 its evaluation changes the lattice value of its output, return
1347 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
1350 If STMT is a conditional branch and we can determine its truth
1351 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
1352 value, return SSA_PROP_VARYING. */
1354 static enum ssa_prop_result
1355 ccp_visit_stmt (tree stmt
, edge
*taken_edge_p
, tree
*output_p
)
1360 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1362 fprintf (dump_file
, "\nVisiting statement:\n");
1363 print_generic_stmt (dump_file
, stmt
, dump_flags
);
1364 fprintf (dump_file
, "\n");
1367 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
)
1369 /* If the statement is an assignment that produces a single
1370 output value, evaluate its RHS to see if the lattice value of
1371 its output has changed. */
1372 return visit_assignment (stmt
, output_p
);
1374 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
1376 /* If STMT is a conditional branch, see if we can determine
1377 which branch will be taken. */
1378 return visit_cond_stmt (stmt
, taken_edge_p
);
1381 /* Any other kind of statement is not interesting for constant
1382 propagation and, therefore, not worth simulating. */
1383 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1384 fprintf (dump_file
, "No interesting values produced. Marked VARYING.\n");
1386 /* Definitions made by statements other than assignments to
1387 SSA_NAMEs represent unknown modifications to their outputs.
1388 Mark them VARYING. */
1389 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
1391 prop_value_t v
= { VARYING
, NULL_TREE
, NULL_TREE
};
1392 set_lattice_value (def
, v
);
1395 return SSA_PROP_VARYING
;
1399 /* Main entry point for SSA Conditional Constant Propagation. */
1402 execute_ssa_ccp (bool store_ccp
)
1404 do_store_ccp
= store_ccp
;
1406 ssa_propagate (ccp_visit_stmt
, ccp_visit_phi_node
);
1414 execute_ssa_ccp (false);
1422 return flag_tree_ccp
!= 0;
1426 struct tree_opt_pass pass_ccp
=
1429 gate_ccp
, /* gate */
1430 do_ssa_ccp
, /* execute */
1433 0, /* static_pass_number */
1434 TV_TREE_CCP
, /* tv_id */
1435 PROP_cfg
| PROP_ssa
| PROP_alias
, /* properties_required */
1436 0, /* properties_provided */
1437 0, /* properties_destroyed */
1438 0, /* todo_flags_start */
1439 TODO_cleanup_cfg
| TODO_dump_func
| TODO_update_ssa
1440 | TODO_ggc_collect
| TODO_verify_ssa
1441 | TODO_verify_stmts
| TODO_update_smt_usage
, /* todo_flags_finish */
1447 do_ssa_store_ccp (void)
1449 /* If STORE-CCP is not enabled, we just run regular CCP. */
1450 execute_ssa_ccp (flag_tree_store_ccp
!= 0);
1455 gate_store_ccp (void)
1457 /* STORE-CCP is enabled only with -ftree-store-ccp, but when
1458 -fno-tree-store-ccp is specified, we should run regular CCP.
1459 That's why the pass is enabled with either flag. */
1460 return flag_tree_store_ccp
!= 0 || flag_tree_ccp
!= 0;
1464 struct tree_opt_pass pass_store_ccp
=
1466 "store_ccp", /* name */
1467 gate_store_ccp
, /* gate */
1468 do_ssa_store_ccp
, /* execute */
1471 0, /* static_pass_number */
1472 TV_TREE_STORE_CCP
, /* tv_id */
1473 PROP_cfg
| PROP_ssa
| PROP_alias
, /* properties_required */
1474 0, /* properties_provided */
1475 0, /* properties_destroyed */
1476 0, /* todo_flags_start */
1477 TODO_dump_func
| TODO_update_ssa
1478 | TODO_ggc_collect
| TODO_verify_ssa
1480 | TODO_verify_stmts
| TODO_update_smt_usage
, /* todo_flags_finish */
1484 /* Given a constant value VAL for bitfield FIELD, and a destination
1485 variable VAR, return VAL appropriately widened to fit into VAR. If
1486 FIELD is wider than HOST_WIDE_INT, NULL is returned. */
1489 widen_bitfield (tree val
, tree field
, tree var
)
1491 unsigned HOST_WIDE_INT var_size
, field_size
;
1493 unsigned HOST_WIDE_INT mask
;
1496 /* We can only do this if the size of the type and field and VAL are
1497 all constants representable in HOST_WIDE_INT. */
1498 if (!host_integerp (TYPE_SIZE (TREE_TYPE (var
)), 1)
1499 || !host_integerp (DECL_SIZE (field
), 1)
1500 || !host_integerp (val
, 0))
1503 var_size
= tree_low_cst (TYPE_SIZE (TREE_TYPE (var
)), 1);
1504 field_size
= tree_low_cst (DECL_SIZE (field
), 1);
1506 /* Give up if either the bitfield or the variable are too wide. */
1507 if (field_size
> HOST_BITS_PER_WIDE_INT
|| var_size
> HOST_BITS_PER_WIDE_INT
)
1510 gcc_assert (var_size
>= field_size
);
1512 /* If the sign bit of the value is not set or the field's type is unsigned,
1513 just mask off the high order bits of the value. */
1514 if (DECL_UNSIGNED (field
)
1515 || !(tree_low_cst (val
, 0) & (((HOST_WIDE_INT
)1) << (field_size
- 1))))
1517 /* Zero extension. Build a mask with the lower 'field_size' bits
1518 set and a BIT_AND_EXPR node to clear the high order bits of
1520 for (i
= 0, mask
= 0; i
< field_size
; i
++)
1521 mask
|= ((HOST_WIDE_INT
) 1) << i
;
1523 wide_val
= fold_build2 (BIT_AND_EXPR
, TREE_TYPE (var
), val
,
1524 build_int_cst (TREE_TYPE (var
), mask
));
1528 /* Sign extension. Create a mask with the upper 'field_size'
1529 bits set and a BIT_IOR_EXPR to set the high order bits of the
1531 for (i
= 0, mask
= 0; i
< (var_size
- field_size
); i
++)
1532 mask
|= ((HOST_WIDE_INT
) 1) << (var_size
- i
- 1);
1534 wide_val
= fold_build2 (BIT_IOR_EXPR
, TREE_TYPE (var
), val
,
1535 build_int_cst (TREE_TYPE (var
), mask
));
1542 /* A subroutine of fold_stmt_r. Attempts to fold *(A+O) to A[X].
1543 BASE is an array type. OFFSET is a byte displacement. ORIG_TYPE
1544 is the desired result type. */
1547 maybe_fold_offset_to_array_ref (tree base
, tree offset
, tree orig_type
)
1549 tree min_idx
, idx
, elt_offset
= integer_zero_node
;
1550 tree array_type
, elt_type
, elt_size
;
1552 /* If BASE is an ARRAY_REF, we can pick up another offset (this time
1553 measured in units of the size of elements type) from that ARRAY_REF).
1554 We can't do anything if either is variable.
1556 The case we handle here is *(&A[N]+O). */
1557 if (TREE_CODE (base
) == ARRAY_REF
)
1559 tree low_bound
= array_ref_low_bound (base
);
1561 elt_offset
= TREE_OPERAND (base
, 1);
1562 if (TREE_CODE (low_bound
) != INTEGER_CST
1563 || TREE_CODE (elt_offset
) != INTEGER_CST
)
1566 elt_offset
= int_const_binop (MINUS_EXPR
, elt_offset
, low_bound
, 0);
1567 base
= TREE_OPERAND (base
, 0);
1570 /* Ignore stupid user tricks of indexing non-array variables. */
1571 array_type
= TREE_TYPE (base
);
1572 if (TREE_CODE (array_type
) != ARRAY_TYPE
)
1574 elt_type
= TREE_TYPE (array_type
);
1575 if (!lang_hooks
.types_compatible_p (orig_type
, elt_type
))
1578 /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the
1579 element type (so we can use the alignment if it's not constant).
1580 Otherwise, compute the offset as an index by using a division. If the
1581 division isn't exact, then don't do anything. */
1582 elt_size
= TYPE_SIZE_UNIT (elt_type
);
1583 if (integer_zerop (offset
))
1585 if (TREE_CODE (elt_size
) != INTEGER_CST
)
1586 elt_size
= size_int (TYPE_ALIGN (elt_type
));
1588 idx
= integer_zero_node
;
1592 unsigned HOST_WIDE_INT lquo
, lrem
;
1593 HOST_WIDE_INT hquo
, hrem
;
1595 if (TREE_CODE (elt_size
) != INTEGER_CST
1596 || div_and_round_double (TRUNC_DIV_EXPR
, 1,
1597 TREE_INT_CST_LOW (offset
),
1598 TREE_INT_CST_HIGH (offset
),
1599 TREE_INT_CST_LOW (elt_size
),
1600 TREE_INT_CST_HIGH (elt_size
),
1601 &lquo
, &hquo
, &lrem
, &hrem
)
1605 idx
= build_int_cst_wide (NULL_TREE
, lquo
, hquo
);
1608 /* Assume the low bound is zero. If there is a domain type, get the
1609 low bound, if any, convert the index into that type, and add the
1611 min_idx
= integer_zero_node
;
1612 if (TYPE_DOMAIN (array_type
))
1614 if (TYPE_MIN_VALUE (TYPE_DOMAIN (array_type
)))
1615 min_idx
= TYPE_MIN_VALUE (TYPE_DOMAIN (array_type
));
1617 min_idx
= fold_convert (TYPE_DOMAIN (array_type
), min_idx
);
1619 if (TREE_CODE (min_idx
) != INTEGER_CST
)
1622 idx
= fold_convert (TYPE_DOMAIN (array_type
), idx
);
1623 elt_offset
= fold_convert (TYPE_DOMAIN (array_type
), elt_offset
);
1626 if (!integer_zerop (min_idx
))
1627 idx
= int_const_binop (PLUS_EXPR
, idx
, min_idx
, 0);
1628 if (!integer_zerop (elt_offset
))
1629 idx
= int_const_binop (PLUS_EXPR
, idx
, elt_offset
, 0);
1631 return build4 (ARRAY_REF
, orig_type
, base
, idx
, min_idx
,
1632 size_int (tree_low_cst (elt_size
, 1)
1633 / (TYPE_ALIGN_UNIT (elt_type
))));
1637 /* A subroutine of fold_stmt_r. Attempts to fold *(S+O) to S.X.
1638 BASE is a record type. OFFSET is a byte displacement. ORIG_TYPE
1639 is the desired result type. */
1640 /* ??? This doesn't handle class inheritance. */
1643 maybe_fold_offset_to_component_ref (tree record_type
, tree base
, tree offset
,
1644 tree orig_type
, bool base_is_ptr
)
1646 tree f
, t
, field_type
, tail_array_field
, field_offset
;
1648 if (TREE_CODE (record_type
) != RECORD_TYPE
1649 && TREE_CODE (record_type
) != UNION_TYPE
1650 && TREE_CODE (record_type
) != QUAL_UNION_TYPE
)
1653 /* Short-circuit silly cases. */
1654 if (lang_hooks
.types_compatible_p (record_type
, orig_type
))
1657 tail_array_field
= NULL_TREE
;
1658 for (f
= TYPE_FIELDS (record_type
); f
; f
= TREE_CHAIN (f
))
1662 if (TREE_CODE (f
) != FIELD_DECL
)
1664 if (DECL_BIT_FIELD (f
))
1667 field_offset
= byte_position (f
);
1668 if (TREE_CODE (field_offset
) != INTEGER_CST
)
1671 /* ??? Java creates "interesting" fields for representing base classes.
1672 They have no name, and have no context. With no context, we get into
1673 trouble with nonoverlapping_component_refs_p. Skip them. */
1674 if (!DECL_FIELD_CONTEXT (f
))
1677 /* The previous array field isn't at the end. */
1678 tail_array_field
= NULL_TREE
;
1680 /* Check to see if this offset overlaps with the field. */
1681 cmp
= tree_int_cst_compare (field_offset
, offset
);
1685 field_type
= TREE_TYPE (f
);
1687 /* Here we exactly match the offset being checked. If the types match,
1688 then we can return that field. */
1690 && lang_hooks
.types_compatible_p (orig_type
, field_type
))
1693 base
= build1 (INDIRECT_REF
, record_type
, base
);
1694 t
= build3 (COMPONENT_REF
, field_type
, base
, f
, NULL_TREE
);
1698 /* Don't care about offsets into the middle of scalars. */
1699 if (!AGGREGATE_TYPE_P (field_type
))
1702 /* Check for array at the end of the struct. This is often
1703 used as for flexible array members. We should be able to
1704 turn this into an array access anyway. */
1705 if (TREE_CODE (field_type
) == ARRAY_TYPE
)
1706 tail_array_field
= f
;
1708 /* Check the end of the field against the offset. */
1709 if (!DECL_SIZE_UNIT (f
)
1710 || TREE_CODE (DECL_SIZE_UNIT (f
)) != INTEGER_CST
)
1712 t
= int_const_binop (MINUS_EXPR
, offset
, field_offset
, 1);
1713 if (!tree_int_cst_lt (t
, DECL_SIZE_UNIT (f
)))
1716 /* If we matched, then set offset to the displacement into
1722 if (!tail_array_field
)
1725 f
= tail_array_field
;
1726 field_type
= TREE_TYPE (f
);
1727 offset
= int_const_binop (MINUS_EXPR
, offset
, byte_position (f
), 1);
1730 /* If we get here, we've got an aggregate field, and a possibly
1731 nonzero offset into them. Recurse and hope for a valid match. */
1733 base
= build1 (INDIRECT_REF
, record_type
, base
);
1734 base
= build3 (COMPONENT_REF
, field_type
, base
, f
, NULL_TREE
);
1736 t
= maybe_fold_offset_to_array_ref (base
, offset
, orig_type
);
1739 return maybe_fold_offset_to_component_ref (field_type
, base
, offset
,
1744 /* A subroutine of fold_stmt_r. Attempt to simplify *(BASE+OFFSET).
1745 Return the simplified expression, or NULL if nothing could be done. */
1748 maybe_fold_stmt_indirect (tree expr
, tree base
, tree offset
)
1752 /* We may well have constructed a double-nested PLUS_EXPR via multiple
1753 substitutions. Fold that down to one. Remove NON_LVALUE_EXPRs that
1754 are sometimes added. */
1756 STRIP_TYPE_NOPS (base
);
1757 TREE_OPERAND (expr
, 0) = base
;
1759 /* One possibility is that the address reduces to a string constant. */
1760 t
= fold_read_from_constant_string (expr
);
1764 /* Add in any offset from a PLUS_EXPR. */
1765 if (TREE_CODE (base
) == PLUS_EXPR
)
1769 offset2
= TREE_OPERAND (base
, 1);
1770 if (TREE_CODE (offset2
) != INTEGER_CST
)
1772 base
= TREE_OPERAND (base
, 0);
1774 offset
= int_const_binop (PLUS_EXPR
, offset
, offset2
, 1);
1777 if (TREE_CODE (base
) == ADDR_EXPR
)
1779 /* Strip the ADDR_EXPR. */
1780 base
= TREE_OPERAND (base
, 0);
1782 /* Fold away CONST_DECL to its value, if the type is scalar. */
1783 if (TREE_CODE (base
) == CONST_DECL
1784 && ccp_decl_initial_min_invariant (DECL_INITIAL (base
)))
1785 return DECL_INITIAL (base
);
1787 /* Try folding *(&B+O) to B[X]. */
1788 t
= maybe_fold_offset_to_array_ref (base
, offset
, TREE_TYPE (expr
));
1792 /* Try folding *(&B+O) to B.X. */
1793 t
= maybe_fold_offset_to_component_ref (TREE_TYPE (base
), base
, offset
,
1794 TREE_TYPE (expr
), false);
1798 /* Fold *&B to B. We can only do this if EXPR is the same type
1799 as BASE. We can't do this if EXPR is the element type of an array
1800 and BASE is the array. */
1801 if (integer_zerop (offset
)
1802 && lang_hooks
.types_compatible_p (TREE_TYPE (base
),
1808 /* We can get here for out-of-range string constant accesses,
1809 such as "_"[3]. Bail out of the entire substitution search
1810 and arrange for the entire statement to be replaced by a
1811 call to __builtin_trap. In all likelihood this will all be
1812 constant-folded away, but in the meantime we can't leave with
1813 something that get_expr_operands can't understand. */
1817 if (TREE_CODE (t
) == ADDR_EXPR
1818 && TREE_CODE (TREE_OPERAND (t
, 0)) == STRING_CST
)
1820 /* FIXME: Except that this causes problems elsewhere with dead
1821 code not being deleted, and we die in the rtl expanders
1822 because we failed to remove some ssa_name. In the meantime,
1823 just return zero. */
1824 /* FIXME2: This condition should be signaled by
1825 fold_read_from_constant_string directly, rather than
1826 re-checking for it here. */
1827 return integer_zero_node
;
1830 /* Try folding *(B+O) to B->X. Still an improvement. */
1831 if (POINTER_TYPE_P (TREE_TYPE (base
)))
1833 t
= maybe_fold_offset_to_component_ref (TREE_TYPE (TREE_TYPE (base
)),
1835 TREE_TYPE (expr
), true);
1841 /* Otherwise we had an offset that we could not simplify. */
1846 /* A subroutine of fold_stmt_r. EXPR is a PLUS_EXPR.
1848 A quaint feature extant in our address arithmetic is that there
1849 can be hidden type changes here. The type of the result need
1850 not be the same as the type of the input pointer.
1852 What we're after here is an expression of the form
1853 (T *)(&array + const)
1854 where the cast doesn't actually exist, but is implicit in the
1855 type of the PLUS_EXPR. We'd like to turn this into
1857 which may be able to propagate further. */
1860 maybe_fold_stmt_addition (tree expr
)
1862 tree op0
= TREE_OPERAND (expr
, 0);
1863 tree op1
= TREE_OPERAND (expr
, 1);
1864 tree ptr_type
= TREE_TYPE (expr
);
1867 bool subtract
= (TREE_CODE (expr
) == MINUS_EXPR
);
1869 /* We're only interested in pointer arithmetic. */
1870 if (!POINTER_TYPE_P (ptr_type
))
1872 /* Canonicalize the integral operand to op1. */
1873 if (INTEGRAL_TYPE_P (TREE_TYPE (op0
)))
1877 t
= op0
, op0
= op1
, op1
= t
;
1879 /* It had better be a constant. */
1880 if (TREE_CODE (op1
) != INTEGER_CST
)
1882 /* The first operand should be an ADDR_EXPR. */
1883 if (TREE_CODE (op0
) != ADDR_EXPR
)
1885 op0
= TREE_OPERAND (op0
, 0);
1887 /* If the first operand is an ARRAY_REF, expand it so that we can fold
1888 the offset into it. */
1889 while (TREE_CODE (op0
) == ARRAY_REF
)
1891 tree array_obj
= TREE_OPERAND (op0
, 0);
1892 tree array_idx
= TREE_OPERAND (op0
, 1);
1893 tree elt_type
= TREE_TYPE (op0
);
1894 tree elt_size
= TYPE_SIZE_UNIT (elt_type
);
1897 if (TREE_CODE (array_idx
) != INTEGER_CST
)
1899 if (TREE_CODE (elt_size
) != INTEGER_CST
)
1902 /* Un-bias the index by the min index of the array type. */
1903 min_idx
= TYPE_DOMAIN (TREE_TYPE (array_obj
));
1906 min_idx
= TYPE_MIN_VALUE (min_idx
);
1909 if (TREE_CODE (min_idx
) != INTEGER_CST
)
1912 array_idx
= fold_convert (TREE_TYPE (min_idx
), array_idx
);
1913 if (!integer_zerop (min_idx
))
1914 array_idx
= int_const_binop (MINUS_EXPR
, array_idx
,
1919 /* Convert the index to a byte offset. */
1920 array_idx
= fold_convert (sizetype
, array_idx
);
1921 array_idx
= int_const_binop (MULT_EXPR
, array_idx
, elt_size
, 0);
1923 /* Update the operands for the next round, or for folding. */
1924 /* If we're manipulating unsigned types, then folding into negative
1925 values can produce incorrect results. Particularly if the type
1926 is smaller than the width of the pointer. */
1928 && TYPE_UNSIGNED (TREE_TYPE (op1
))
1929 && tree_int_cst_lt (array_idx
, op1
))
1931 op1
= int_const_binop (subtract
? MINUS_EXPR
: PLUS_EXPR
,
1937 /* If we weren't able to fold the subtraction into another array reference,
1938 canonicalize the integer for passing to the array and component ref
1939 simplification functions. */
1942 if (TYPE_UNSIGNED (TREE_TYPE (op1
)))
1944 op1
= fold_unary (NEGATE_EXPR
, TREE_TYPE (op1
), op1
);
1945 /* ??? In theory fold should always produce another integer. */
1946 if (op1
== NULL
|| TREE_CODE (op1
) != INTEGER_CST
)
1950 ptd_type
= TREE_TYPE (ptr_type
);
1952 /* At which point we can try some of the same things as for indirects. */
1953 t
= maybe_fold_offset_to_array_ref (op0
, op1
, ptd_type
);
1955 t
= maybe_fold_offset_to_component_ref (TREE_TYPE (op0
), op0
, op1
,
1958 t
= build1 (ADDR_EXPR
, ptr_type
, t
);
1963 /* For passing state through walk_tree into fold_stmt_r and its
1966 struct fold_stmt_r_data
1969 bool *inside_addr_expr_p
;
1972 /* Subroutine of fold_stmt called via walk_tree. We perform several
1973 simplifications of EXPR_P, mostly having to do with pointer arithmetic. */
1976 fold_stmt_r (tree
*expr_p
, int *walk_subtrees
, void *data
)
1978 struct fold_stmt_r_data
*fold_stmt_r_data
= (struct fold_stmt_r_data
*) data
;
1979 bool *inside_addr_expr_p
= fold_stmt_r_data
->inside_addr_expr_p
;
1980 bool *changed_p
= fold_stmt_r_data
->changed_p
;
1981 tree expr
= *expr_p
, t
;
1983 /* ??? It'd be nice if walk_tree had a pre-order option. */
1984 switch (TREE_CODE (expr
))
1987 t
= walk_tree (&TREE_OPERAND (expr
, 0), fold_stmt_r
, data
, NULL
);
1992 t
= maybe_fold_stmt_indirect (expr
, TREE_OPERAND (expr
, 0),
1996 /* ??? Could handle more ARRAY_REFs here, as a variant of INDIRECT_REF.
1997 We'd only want to bother decomposing an existing ARRAY_REF if
1998 the base array is found to have another offset contained within.
1999 Otherwise we'd be wasting time. */
2001 /* If we are not processing expressions found within an
2002 ADDR_EXPR, then we can fold constant array references. */
2003 if (!*inside_addr_expr_p
)
2004 t
= fold_read_from_constant_string (expr
);
2010 *inside_addr_expr_p
= true;
2011 t
= walk_tree (&TREE_OPERAND (expr
, 0), fold_stmt_r
, data
, NULL
);
2012 *inside_addr_expr_p
= false;
2017 /* Set TREE_INVARIANT properly so that the value is properly
2018 considered constant, and so gets propagated as expected. */
2020 recompute_tree_invariant_for_addr_expr (expr
);
2025 t
= walk_tree (&TREE_OPERAND (expr
, 0), fold_stmt_r
, data
, NULL
);
2028 t
= walk_tree (&TREE_OPERAND (expr
, 1), fold_stmt_r
, data
, NULL
);
2033 t
= maybe_fold_stmt_addition (expr
);
2037 t
= walk_tree (&TREE_OPERAND (expr
, 0), fold_stmt_r
, data
, NULL
);
2042 /* Make sure the FIELD_DECL is actually a field in the type on the lhs.
2043 We've already checked that the records are compatible, so we should
2044 come up with a set of compatible fields. */
2046 tree expr_record
= TREE_TYPE (TREE_OPERAND (expr
, 0));
2047 tree expr_field
= TREE_OPERAND (expr
, 1);
2049 if (DECL_FIELD_CONTEXT (expr_field
) != TYPE_MAIN_VARIANT (expr_record
))
2051 expr_field
= find_compatible_field (expr_record
, expr_field
);
2052 TREE_OPERAND (expr
, 1) = expr_field
;
2057 case TARGET_MEM_REF
:
2058 t
= maybe_fold_tmr (expr
);
2062 if (COMPARISON_CLASS_P (TREE_OPERAND (expr
, 0)))
2064 tree op0
= TREE_OPERAND (expr
, 0);
2065 tree tem
= fold_binary (TREE_CODE (op0
), TREE_TYPE (op0
),
2066 TREE_OPERAND (op0
, 0),
2067 TREE_OPERAND (op0
, 1));
2068 if (tem
&& set_rhs (expr_p
, tem
))
2090 /* Return the string length, maximum string length or maximum value of
2092 If ARG is an SSA name variable, follow its use-def chains. If LENGTH
2093 is not NULL and, for TYPE == 0, its value is not equal to the length
2094 we determine or if we are unable to determine the length or value,
2095 return false. VISITED is a bitmap of visited variables.
2096 TYPE is 0 if string length should be returned, 1 for maximum string
2097 length and 2 for maximum value ARG can have. */
2100 get_maxval_strlen (tree arg
, tree
*length
, bitmap visited
, int type
)
2102 tree var
, def_stmt
, val
;
2104 if (TREE_CODE (arg
) != SSA_NAME
)
2109 if (TREE_CODE (val
) != INTEGER_CST
2110 || tree_int_cst_sgn (val
) < 0)
2114 val
= c_strlen (arg
, 1);
2122 if (TREE_CODE (*length
) != INTEGER_CST
2123 || TREE_CODE (val
) != INTEGER_CST
)
2126 if (tree_int_cst_lt (*length
, val
))
2130 else if (simple_cst_equal (val
, *length
) != 1)
2138 /* If we were already here, break the infinite cycle. */
2139 if (bitmap_bit_p (visited
, SSA_NAME_VERSION (arg
)))
2141 bitmap_set_bit (visited
, SSA_NAME_VERSION (arg
));
2144 def_stmt
= SSA_NAME_DEF_STMT (var
);
2146 switch (TREE_CODE (def_stmt
))
2148 case GIMPLE_MODIFY_STMT
:
2152 /* The RHS of the statement defining VAR must either have a
2153 constant length or come from another SSA_NAME with a constant
2155 rhs
= GIMPLE_STMT_OPERAND (def_stmt
, 1);
2157 return get_maxval_strlen (rhs
, length
, visited
, type
);
2162 /* All the arguments of the PHI node must have the same constant
2166 for (i
= 0; i
< PHI_NUM_ARGS (def_stmt
); i
++)
2168 tree arg
= PHI_ARG_DEF (def_stmt
, i
);
2170 /* If this PHI has itself as an argument, we cannot
2171 determine the string length of this argument. However,
2172 if we can find a constant string length for the other
2173 PHI args then we can still be sure that this is a
2174 constant string length. So be optimistic and just
2175 continue with the next argument. */
2176 if (arg
== PHI_RESULT (def_stmt
))
2179 if (!get_maxval_strlen (arg
, length
, visited
, type
))
2195 /* Fold builtin call FN in statement STMT. If it cannot be folded into a
2196 constant, return NULL_TREE. Otherwise, return its constant value. */
2199 ccp_fold_builtin (tree stmt
, tree fn
)
2201 tree result
, val
[3];
2202 tree callee
, arglist
, a
;
2203 int arg_mask
, i
, type
;
2207 ignore
= TREE_CODE (stmt
) != GIMPLE_MODIFY_STMT
;
2209 /* First try the generic builtin folder. If that succeeds, return the
2211 callee
= get_callee_fndecl (fn
);
2212 arglist
= TREE_OPERAND (fn
, 1);
2213 result
= fold_builtin (callee
, arglist
, ignore
);
2217 STRIP_NOPS (result
);
2221 /* Ignore MD builtins. */
2222 if (DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_MD
)
2225 /* If the builtin could not be folded, and it has no argument list,
2230 /* Limit the work only for builtins we know how to simplify. */
2231 switch (DECL_FUNCTION_CODE (callee
))
2233 case BUILT_IN_STRLEN
:
2234 case BUILT_IN_FPUTS
:
2235 case BUILT_IN_FPUTS_UNLOCKED
:
2239 case BUILT_IN_STRCPY
:
2240 case BUILT_IN_STRNCPY
:
2244 case BUILT_IN_MEMCPY_CHK
:
2245 case BUILT_IN_MEMPCPY_CHK
:
2246 case BUILT_IN_MEMMOVE_CHK
:
2247 case BUILT_IN_MEMSET_CHK
:
2248 case BUILT_IN_STRNCPY_CHK
:
2252 case BUILT_IN_STRCPY_CHK
:
2253 case BUILT_IN_STPCPY_CHK
:
2257 case BUILT_IN_SNPRINTF_CHK
:
2258 case BUILT_IN_VSNPRINTF_CHK
:
2266 /* Try to use the dataflow information gathered by the CCP process. */
2267 visited
= BITMAP_ALLOC (NULL
);
2269 memset (val
, 0, sizeof (val
));
2270 for (i
= 0, a
= arglist
;
2272 i
++, arg_mask
>>= 1, a
= TREE_CHAIN (a
))
2275 bitmap_clear (visited
);
2276 if (!get_maxval_strlen (TREE_VALUE (a
), &val
[i
], visited
, type
))
2280 BITMAP_FREE (visited
);
2283 switch (DECL_FUNCTION_CODE (callee
))
2285 case BUILT_IN_STRLEN
:
2288 tree
new = fold_convert (TREE_TYPE (fn
), val
[0]);
2290 /* If the result is not a valid gimple value, or not a cast
2291 of a valid gimple value, then we can not use the result. */
2292 if (is_gimple_val (new)
2293 || (is_gimple_cast (new)
2294 && is_gimple_val (TREE_OPERAND (new, 0))))
2299 case BUILT_IN_STRCPY
:
2300 if (val
[1] && is_gimple_val (val
[1]))
2301 result
= fold_builtin_strcpy (callee
, arglist
, val
[1]);
2304 case BUILT_IN_STRNCPY
:
2305 if (val
[1] && is_gimple_val (val
[1]))
2306 result
= fold_builtin_strncpy (callee
, arglist
, val
[1]);
2309 case BUILT_IN_FPUTS
:
2310 result
= fold_builtin_fputs (arglist
,
2311 TREE_CODE (stmt
) != GIMPLE_MODIFY_STMT
, 0,
2315 case BUILT_IN_FPUTS_UNLOCKED
:
2316 result
= fold_builtin_fputs (arglist
,
2317 TREE_CODE (stmt
) != GIMPLE_MODIFY_STMT
, 1,
2321 case BUILT_IN_MEMCPY_CHK
:
2322 case BUILT_IN_MEMPCPY_CHK
:
2323 case BUILT_IN_MEMMOVE_CHK
:
2324 case BUILT_IN_MEMSET_CHK
:
2325 if (val
[2] && is_gimple_val (val
[2]))
2326 result
= fold_builtin_memory_chk (callee
, arglist
, val
[2], ignore
,
2327 DECL_FUNCTION_CODE (callee
));
2330 case BUILT_IN_STRCPY_CHK
:
2331 case BUILT_IN_STPCPY_CHK
:
2332 if (val
[1] && is_gimple_val (val
[1]))
2333 result
= fold_builtin_stxcpy_chk (callee
, arglist
, val
[1], ignore
,
2334 DECL_FUNCTION_CODE (callee
));
2337 case BUILT_IN_STRNCPY_CHK
:
2338 if (val
[2] && is_gimple_val (val
[2]))
2339 result
= fold_builtin_strncpy_chk (arglist
, val
[2]);
2342 case BUILT_IN_SNPRINTF_CHK
:
2343 case BUILT_IN_VSNPRINTF_CHK
:
2344 if (val
[1] && is_gimple_val (val
[1]))
2345 result
= fold_builtin_snprintf_chk (arglist
, val
[1],
2346 DECL_FUNCTION_CODE (callee
));
2353 if (result
&& ignore
)
2354 result
= fold_ignored_result (result
);
2359 /* Fold the statement pointed to by STMT_P. In some cases, this function may
2360 replace the whole statement with a new one. Returns true iff folding
2361 makes any changes. */
2364 fold_stmt (tree
*stmt_p
)
2366 tree rhs
, result
, stmt
;
2367 struct fold_stmt_r_data fold_stmt_r_data
;
2368 bool changed
= false;
2369 bool inside_addr_expr
= false;
2371 fold_stmt_r_data
.changed_p
= &changed
;
2372 fold_stmt_r_data
.inside_addr_expr_p
= &inside_addr_expr
;
2376 /* If we replaced constants and the statement makes pointer dereferences,
2377 then we may need to fold instances of *&VAR into VAR, etc. */
2378 if (walk_tree (stmt_p
, fold_stmt_r
, &fold_stmt_r_data
, NULL
))
2381 = build_function_call_expr (implicit_built_in_decls
[BUILT_IN_TRAP
],
2386 rhs
= get_rhs (stmt
);
2391 if (TREE_CODE (rhs
) == CALL_EXPR
)
2395 /* Check for builtins that CCP can handle using information not
2396 available in the generic fold routines. */
2397 callee
= get_callee_fndecl (rhs
);
2398 if (callee
&& DECL_BUILT_IN (callee
))
2399 result
= ccp_fold_builtin (stmt
, rhs
);
2402 /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve
2403 here are when we've propagated the address of a decl into the
2405 /* ??? Should perhaps do this in fold proper. However, doing it
2406 there requires that we create a new CALL_EXPR, and that requires
2407 copying EH region info to the new node. Easier to just do it
2408 here where we can just smash the call operand. Also
2409 CALL_EXPR_RETURN_SLOT_OPT needs to be handled correctly and
2410 copied, fold_ternary does not have not information. */
2411 callee
= TREE_OPERAND (rhs
, 0);
2412 if (TREE_CODE (callee
) == OBJ_TYPE_REF
2413 && lang_hooks
.fold_obj_type_ref
2414 && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee
)) == ADDR_EXPR
2415 && DECL_P (TREE_OPERAND
2416 (OBJ_TYPE_REF_OBJECT (callee
), 0)))
2420 /* ??? Caution: Broken ADDR_EXPR semantics means that
2421 looking at the type of the operand of the addr_expr
2422 can yield an array type. See silly exception in
2423 check_pointer_types_r. */
2425 t
= TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee
)));
2426 t
= lang_hooks
.fold_obj_type_ref (callee
, t
);
2429 TREE_OPERAND (rhs
, 0) = t
;
2436 /* If we couldn't fold the RHS, hand over to the generic fold routines. */
2437 if (result
== NULL_TREE
)
2438 result
= fold (rhs
);
2440 /* Strip away useless type conversions. Both the NON_LVALUE_EXPR that
2441 may have been added by fold, and "useless" type conversions that might
2442 now be apparent due to propagation. */
2443 STRIP_USELESS_TYPE_CONVERSION (result
);
2446 changed
|= set_rhs (stmt_p
, result
);
2451 /* Perform the minimal folding on statement STMT. Only operations like
2452 *&x created by constant propagation are handled. The statement cannot
2453 be replaced with a new one. */
2456 fold_stmt_inplace (tree stmt
)
2458 tree old_stmt
= stmt
, rhs
, new_rhs
;
2459 struct fold_stmt_r_data fold_stmt_r_data
;
2460 bool changed
= false;
2461 bool inside_addr_expr
= false;
2463 fold_stmt_r_data
.changed_p
= &changed
;
2464 fold_stmt_r_data
.inside_addr_expr_p
= &inside_addr_expr
;
2466 walk_tree (&stmt
, fold_stmt_r
, &fold_stmt_r_data
, NULL
);
2467 gcc_assert (stmt
== old_stmt
);
2469 rhs
= get_rhs (stmt
);
2470 if (!rhs
|| rhs
== stmt
)
2473 new_rhs
= fold (rhs
);
2474 STRIP_USELESS_TYPE_CONVERSION (new_rhs
);
2478 changed
|= set_rhs (&stmt
, new_rhs
);
2479 gcc_assert (stmt
== old_stmt
);
2484 /* Convert EXPR into a GIMPLE value suitable for substitution on the
2485 RHS of an assignment. Insert the necessary statements before
2487 When IGNORE is set, don't worry about the return value. */
2490 convert_to_gimple_builtin (block_stmt_iterator
*si_p
, tree expr
, bool ignore
)
2492 tree_stmt_iterator ti
;
2493 tree stmt
= bsi_stmt (*si_p
);
2494 tree tmp
, stmts
= NULL
;
2496 push_gimplify_context ();
2499 tmp
= build_empty_stmt ();
2500 gimplify_and_add (expr
, &stmts
);
2503 tmp
= get_initialized_tmp_var (expr
, &stmts
, NULL
);
2504 pop_gimplify_context (NULL
);
2506 if (EXPR_HAS_LOCATION (stmt
))
2507 annotate_all_with_locus (&stmts
, EXPR_LOCATION (stmt
));
2509 /* The replacement can expose previously unreferenced variables. */
2510 for (ti
= tsi_start (stmts
); !tsi_end_p (ti
); tsi_next (&ti
))
2512 tree new_stmt
= tsi_stmt (ti
);
2513 find_new_referenced_vars (tsi_stmt_ptr (ti
));
2514 bsi_insert_before (si_p
, new_stmt
, BSI_NEW_STMT
);
2515 mark_new_vars_to_rename (bsi_stmt (*si_p
));
2523 /* A simple pass that attempts to fold all builtin functions. This pass
2524 is run after we've propagated as many constants as we can. */
2527 execute_fold_all_builtins (void)
2529 bool cfg_changed
= false;
2533 block_stmt_iterator i
;
2534 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
2536 tree
*stmtp
= bsi_stmt_ptr (i
);
2537 tree old_stmt
= *stmtp
;
2538 tree call
= get_rhs (*stmtp
);
2539 tree callee
, result
;
2540 enum built_in_function fcode
;
2542 if (!call
|| TREE_CODE (call
) != CALL_EXPR
)
2547 callee
= get_callee_fndecl (call
);
2548 if (!callee
|| DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
)
2553 fcode
= DECL_FUNCTION_CODE (callee
);
2555 result
= ccp_fold_builtin (*stmtp
, call
);
2557 switch (DECL_FUNCTION_CODE (callee
))
2559 case BUILT_IN_CONSTANT_P
:
2560 /* Resolve __builtin_constant_p. If it hasn't been
2561 folded to integer_one_node by now, it's fairly
2562 certain that the value simply isn't constant. */
2563 result
= integer_zero_node
;
2571 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2573 fprintf (dump_file
, "Simplified\n ");
2574 print_generic_stmt (dump_file
, *stmtp
, dump_flags
);
2577 if (!set_rhs (stmtp
, result
))
2579 result
= convert_to_gimple_builtin (&i
, result
,
2580 TREE_CODE (old_stmt
)
2581 != GIMPLE_MODIFY_STMT
);
2584 bool ok
= set_rhs (stmtp
, result
);
2589 mark_new_vars_to_rename (*stmtp
);
2590 if (maybe_clean_or_replace_eh_stmt (old_stmt
, *stmtp
)
2591 && tree_purge_dead_eh_edges (bb
))
2594 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2596 fprintf (dump_file
, "to\n ");
2597 print_generic_stmt (dump_file
, *stmtp
, dump_flags
);
2598 fprintf (dump_file
, "\n");
2601 /* Retry the same statement if it changed into another
2602 builtin, there might be new opportunities now. */
2603 call
= get_rhs (*stmtp
);
2604 if (!call
|| TREE_CODE (call
) != CALL_EXPR
)
2609 callee
= get_callee_fndecl (call
);
2611 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2612 || DECL_FUNCTION_CODE (callee
) == fcode
)
2617 /* Delete unreachable blocks. */
2619 cleanup_tree_cfg ();
2624 struct tree_opt_pass pass_fold_builtins
=
2628 execute_fold_all_builtins
, /* execute */
2631 0, /* static_pass_number */
2633 PROP_cfg
| PROP_ssa
| PROP_alias
, /* properties_required */
2634 0, /* properties_provided */
2635 0, /* properties_destroyed */
2636 0, /* todo_flags_start */
2639 | TODO_update_ssa
, /* todo_flags_finish */