1 /* Conditional constant propagation pass for the GNU compiler.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
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 3, 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 COPYING3. If not see
21 <http://www.gnu.org/licenses/>. */
23 /* Conditional constant propagation (CCP) is based on the SSA
24 propagation engine (tree-ssa-propagate.c). Constant assignments of
25 the form VAR = CST are propagated from the assignments into uses of
26 VAR, which in turn may generate new constants. The simulation uses
27 a four level lattice to keep track of constant values associated
28 with SSA names. Given an SSA name V_i, it may take one of the
31 UNINITIALIZED -> the initial state of the value. This value
32 is replaced with a correct initial value
33 the first time the value is used, so the
34 rest of the pass does not need to care about
35 it. Using this value simplifies initialization
36 of the pass, and prevents us from needlessly
37 scanning statements that are never reached.
39 UNDEFINED -> V_i is a local variable whose definition
40 has not been processed yet. Therefore we
41 don't yet know if its value is a constant
44 CONSTANT -> V_i has been found to hold a constant
47 VARYING -> V_i cannot take a constant value, or if it
48 does, it is not possible to determine it
51 The core of SSA-CCP is in ccp_visit_stmt and ccp_visit_phi_node:
53 1- In ccp_visit_stmt, we are interested in assignments whose RHS
54 evaluates into a constant and conditional jumps whose predicate
55 evaluates into a boolean true or false. When an assignment of
56 the form V_i = CONST is found, V_i's lattice value is set to
57 CONSTANT and CONST is associated with it. This causes the
58 propagation engine to add all the SSA edges coming out the
59 assignment into the worklists, so that statements that use V_i
62 If the statement is a conditional with a constant predicate, we
63 mark the outgoing edges as executable or not executable
64 depending on the predicate's value. This is then used when
65 visiting PHI nodes to know when a PHI argument can be ignored.
68 2- In ccp_visit_phi_node, if all the PHI arguments evaluate to the
69 same constant C, then the LHS of the PHI is set to C. This
70 evaluation is known as the "meet operation". Since one of the
71 goals of this evaluation is to optimistically return constant
72 values as often as possible, it uses two main short cuts:
74 - If an argument is flowing in through a non-executable edge, it
75 is ignored. This is useful in cases like this:
81 a_11 = PHI (a_9, a_10)
83 If PRED is known to always evaluate to false, then we can
84 assume that a_11 will always take its value from a_10, meaning
85 that instead of consider it VARYING (a_9 and a_10 have
86 different values), we can consider it CONSTANT 100.
88 - If an argument has an UNDEFINED value, then it does not affect
89 the outcome of the meet operation. If a variable V_i has an
90 UNDEFINED value, it means that either its defining statement
91 hasn't been visited yet or V_i has no defining statement, in
92 which case the original symbol 'V' is being used
93 uninitialized. Since 'V' is a local variable, the compiler
94 may assume any initial value for it.
97 After propagation, every variable V_i that ends up with a lattice
98 value of CONSTANT will have the associated constant value in the
99 array CONST_VAL[i].VALUE. That is fed into substitute_and_fold for
100 final substitution and folding.
103 Constant propagation in stores and loads (STORE-CCP)
104 ----------------------------------------------------
106 While CCP has all the logic to propagate constants in GIMPLE
107 registers, it is missing the ability to associate constants with
108 stores and loads (i.e., pointer dereferences, structures and
109 global/aliased variables). We don't keep loads and stores in
110 SSA, but we do build a factored use-def web for them (in the
113 For instance, consider the following code fragment:
132 We should be able to deduce that the predicate 'a.a != B' is always
133 false. To achieve this, we associate constant values to the SSA
134 names in the VDEF operands for each store. Additionally,
135 since we also glob partial loads/stores with the base symbol, we
136 also keep track of the memory reference where the constant value
137 was stored (in the MEM_REF field of PROP_VALUE_T). For instance,
145 In the example above, CCP will associate value '2' with 'a_5', but
146 it would be wrong to replace the load from 'a.b' with '2', because
147 '2' had been stored into a.a.
149 Note that the initial value of virtual operands is VARYING, not
150 UNDEFINED. 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;'.
170 Though STORE-CCP is not too expensive, it does have to do more work
171 than regular CCP, so it is only enabled at -O2. Both regular CCP
172 and STORE-CCP use the exact same algorithm. The only distinction
173 is that when doing STORE-CCP, the boolean variable DO_STORE_CCP is
174 set to true. This affects the evaluation of statements and PHI
179 Constant propagation with conditional branches,
180 Wegman and Zadeck, ACM TOPLAS 13(2):181-210.
182 Building an Optimizing Compiler,
183 Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9.
185 Advanced Compiler Design and Implementation,
186 Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */
190 #include "coretypes.h"
197 #include "basic-block.h"
200 #include "function.h"
201 #include "diagnostic.h"
203 #include "tree-dump.h"
204 #include "tree-flow.h"
205 #include "tree-pass.h"
206 #include "tree-ssa-propagate.h"
207 #include "value-prof.h"
208 #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 VDEF), CONST_VAL[I].MEM_REF will contain the actual
226 memory reference used to store (i.e., the LHS of the assignment
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 undefinedness of operands of STMT cause its value to be
512 undefined, then return UNDEFINED.
514 Else if any operands of STMT are constants, then return CONSTANT.
516 Else return VARYING. */
519 likely_value (tree stmt
)
521 bool has_constant_operand
, has_undefined_operand
, all_undefined_operands
;
526 ann
= stmt_ann (stmt
);
528 /* If the statement has volatile operands, it won't fold to a
530 if (ann
->has_volatile_ops
)
533 /* If we are not doing store-ccp, statements with loads
534 and/or stores will never fold into a constant. */
536 && !ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
540 /* A CALL_EXPR is assumed to be varying. NOTE: This may be overly
541 conservative, in the presence of const and pure calls. */
542 if (get_call_expr_in (stmt
) != NULL_TREE
)
545 /* Anything other than assignments and conditional jumps are not
546 interesting for CCP. */
547 if (TREE_CODE (stmt
) != GIMPLE_MODIFY_STMT
548 && !(TREE_CODE (stmt
) == RETURN_EXPR
&& get_rhs (stmt
) != NULL_TREE
)
549 && TREE_CODE (stmt
) != COND_EXPR
550 && TREE_CODE (stmt
) != SWITCH_EXPR
)
553 if (is_gimple_min_invariant (get_rhs (stmt
)))
556 has_constant_operand
= false;
557 has_undefined_operand
= false;
558 all_undefined_operands
= true;
559 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, iter
, SSA_OP_USE
| SSA_OP_VUSE
)
561 prop_value_t
*val
= get_value (use
);
563 if (val
->lattice_val
== UNDEFINED
)
564 has_undefined_operand
= true;
566 all_undefined_operands
= false;
568 if (val
->lattice_val
== CONSTANT
)
569 has_constant_operand
= true;
572 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
)
574 tree rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
575 if (REFERENCE_CLASS_P (rhs
))
577 if (is_gimple_min_invariant (TREE_OPERAND (rhs
, 0)))
578 has_constant_operand
= true;
580 else if (EXPR_P (rhs
))
583 for (i
= 0; i
< TREE_CODE_LENGTH (TREE_CODE (rhs
)); ++i
)
584 if (TREE_OPERAND (rhs
, i
)
585 && is_gimple_min_invariant (TREE_OPERAND (rhs
, i
)))
586 has_constant_operand
= true;
589 else if (TREE_CODE (stmt
) == CALL_EXPR
)
592 for (i
= 0; i
< call_expr_nargs (stmt
); ++i
)
593 if (is_gimple_min_invariant (CALL_EXPR_ARG (stmt
, i
)))
594 has_constant_operand
= true;
597 if (has_constant_operand
)
598 all_undefined_operands
= false;
600 /* If the operation combines operands like COMPLEX_EXPR make sure to
601 not mark the result UNDEFINED if only one part of the result is
603 if (has_undefined_operand
604 && all_undefined_operands
)
606 else if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
607 && has_undefined_operand
)
609 switch (TREE_CODE (GIMPLE_STMT_OPERAND (stmt
, 1)))
611 /* Unary operators are handled with all_undefined_operands. */
614 case POINTER_PLUS_EXPR
:
615 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected.
616 Not bitwise operators, one VARYING operand may specify the
617 result completely. Not logical operators for the same reason.
618 Not COMPLEX_EXPR as one VARYING operand makes the result partly
619 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because
620 the undefined operand may be promoted. */
627 /* If there was an UNDEFINED operand but the result may be not UNDEFINED
628 fall back to VARYING even if there were CONSTANT operands. */
629 if (has_undefined_operand
)
632 if (has_constant_operand
633 /* We do not consider virtual operands here -- load from read-only
634 memory may have only VARYING virtual operands, but still be
636 || ZERO_SSA_OPERANDS (stmt
, SSA_OP_USE
))
642 /* Returns true if STMT cannot be constant. */
645 surely_varying_stmt_p (tree stmt
)
647 /* If the statement has operands that we cannot handle, it cannot be
649 if (stmt_ann (stmt
)->has_volatile_ops
)
652 if (!ZERO_SSA_OPERANDS (stmt
, SSA_OP_ALL_VIRTUALS
))
657 /* We can only handle simple loads and stores. */
658 if (!stmt_makes_single_load (stmt
)
659 && !stmt_makes_single_store (stmt
))
663 /* If it contains a call, it is varying. */
664 if (get_call_expr_in (stmt
) != NULL_TREE
)
667 /* Anything other than assignments and conditional jumps are not
668 interesting for CCP. */
669 if (TREE_CODE (stmt
) != GIMPLE_MODIFY_STMT
670 && !(TREE_CODE (stmt
) == RETURN_EXPR
&& get_rhs (stmt
) != NULL_TREE
)
671 && TREE_CODE (stmt
) != COND_EXPR
672 && TREE_CODE (stmt
) != SWITCH_EXPR
)
678 /* Initialize local data structures for CCP. */
681 ccp_initialize (void)
685 const_val
= XCNEWVEC (prop_value_t
, num_ssa_names
);
687 /* Initialize simulation flags for PHI nodes and statements. */
690 block_stmt_iterator i
;
692 for (i
= bsi_start (bb
); !bsi_end_p (i
); bsi_next (&i
))
694 tree stmt
= bsi_stmt (i
);
695 bool is_varying
= surely_varying_stmt_p (stmt
);
702 /* If the statement will not produce a constant, mark
703 all its outputs VARYING. */
704 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
707 set_value_varying (def
);
711 DONT_SIMULATE_AGAIN (stmt
) = is_varying
;
715 /* Now process PHI nodes. We never set DONT_SIMULATE_AGAIN on phi node,
716 since we do not know which edges are executable yet, except for
717 phi nodes for virtual operands when we do not do store ccp. */
722 for (phi
= phi_nodes (bb
); phi
; phi
= PHI_CHAIN (phi
))
724 if (!do_store_ccp
&& !is_gimple_reg (PHI_RESULT (phi
)))
725 DONT_SIMULATE_AGAIN (phi
) = true;
727 DONT_SIMULATE_AGAIN (phi
) = false;
733 /* Do final substitution of propagated values, cleanup the flowgraph and
734 free allocated storage.
736 Return TRUE when something was optimized. */
741 /* Perform substitutions based on the known constant values. */
742 bool something_changed
= substitute_and_fold (const_val
, false);
745 return something_changed
;;
749 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
752 any M UNDEFINED = any
753 any M VARYING = VARYING
754 Ci M Cj = Ci if (i == j)
755 Ci M Cj = VARYING if (i != j)
759 ccp_lattice_meet (prop_value_t
*val1
, prop_value_t
*val2
)
761 if (val1
->lattice_val
== UNDEFINED
)
763 /* UNDEFINED M any = any */
766 else if (val2
->lattice_val
== UNDEFINED
)
768 /* any M UNDEFINED = any
769 Nothing to do. VAL1 already contains the value we want. */
772 else if (val1
->lattice_val
== VARYING
773 || val2
->lattice_val
== VARYING
)
775 /* any M VARYING = VARYING. */
776 val1
->lattice_val
= VARYING
;
777 val1
->value
= NULL_TREE
;
778 val1
->mem_ref
= NULL_TREE
;
780 else if (val1
->lattice_val
== CONSTANT
781 && val2
->lattice_val
== CONSTANT
782 && simple_cst_equal (val1
->value
, val2
->value
) == 1
784 || (val1
->mem_ref
&& val2
->mem_ref
785 && operand_equal_p (val1
->mem_ref
, val2
->mem_ref
, 0))))
787 /* Ci M Cj = Ci if (i == j)
788 Ci M Cj = VARYING if (i != j)
790 If these two values come from memory stores, make sure that
791 they come from the same memory reference. */
792 val1
->lattice_val
= CONSTANT
;
793 val1
->value
= val1
->value
;
794 val1
->mem_ref
= val1
->mem_ref
;
798 /* Any other combination is VARYING. */
799 val1
->lattice_val
= VARYING
;
800 val1
->value
= NULL_TREE
;
801 val1
->mem_ref
= NULL_TREE
;
806 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
807 lattice values to determine PHI_NODE's lattice value. The value of a
808 PHI node is determined calling ccp_lattice_meet with all the arguments
809 of the PHI node that are incoming via executable edges. */
811 static enum ssa_prop_result
812 ccp_visit_phi_node (tree phi
)
815 prop_value_t
*old_val
, new_val
;
817 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
819 fprintf (dump_file
, "\nVisiting PHI node: ");
820 print_generic_expr (dump_file
, phi
, dump_flags
);
823 old_val
= get_value (PHI_RESULT (phi
));
824 switch (old_val
->lattice_val
)
827 return SSA_PROP_VARYING
;
834 new_val
.lattice_val
= UNDEFINED
;
835 new_val
.value
= NULL_TREE
;
836 new_val
.mem_ref
= NULL_TREE
;
843 for (i
= 0; i
< PHI_NUM_ARGS (phi
); i
++)
845 /* Compute the meet operator over all the PHI arguments flowing
846 through executable edges. */
847 edge e
= PHI_ARG_EDGE (phi
, i
);
849 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
852 "\n Argument #%d (%d -> %d %sexecutable)\n",
853 i
, e
->src
->index
, e
->dest
->index
,
854 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
857 /* If the incoming edge is executable, Compute the meet operator for
858 the existing value of the PHI node and the current PHI argument. */
859 if (e
->flags
& EDGE_EXECUTABLE
)
861 tree arg
= PHI_ARG_DEF (phi
, i
);
862 prop_value_t arg_val
;
864 if (is_gimple_min_invariant (arg
))
866 arg_val
.lattice_val
= CONSTANT
;
868 arg_val
.mem_ref
= NULL_TREE
;
871 arg_val
= *(get_value (arg
));
873 ccp_lattice_meet (&new_val
, &arg_val
);
875 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
877 fprintf (dump_file
, "\t");
878 print_generic_expr (dump_file
, arg
, dump_flags
);
879 dump_lattice_value (dump_file
, "\tValue: ", arg_val
);
880 fprintf (dump_file
, "\n");
883 if (new_val
.lattice_val
== VARYING
)
888 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
890 dump_lattice_value (dump_file
, "\n PHI node value: ", new_val
);
891 fprintf (dump_file
, "\n\n");
894 /* Make the transition to the new value. */
895 if (set_lattice_value (PHI_RESULT (phi
), new_val
))
897 if (new_val
.lattice_val
== VARYING
)
898 return SSA_PROP_VARYING
;
900 return SSA_PROP_INTERESTING
;
903 return SSA_PROP_NOT_INTERESTING
;
907 /* CCP specific front-end to the non-destructive constant folding
910 Attempt to simplify the RHS of STMT knowing that one or more
911 operands are constants.
913 If simplification is possible, return the simplified RHS,
914 otherwise return the original RHS. */
919 tree rhs
= get_rhs (stmt
);
920 enum tree_code code
= TREE_CODE (rhs
);
921 enum tree_code_class kind
= TREE_CODE_CLASS (code
);
922 tree retval
= NULL_TREE
;
924 if (TREE_CODE (rhs
) == SSA_NAME
)
926 /* If the RHS is an SSA_NAME, return its known constant value,
928 return get_value (rhs
)->value
;
930 else if (do_store_ccp
&& stmt_makes_single_load (stmt
))
932 /* If the RHS is a memory load, see if the VUSEs associated with
933 it are a valid constant for that memory load. */
934 prop_value_t
*val
= get_value_loaded_by (stmt
, const_val
);
935 if (val
&& val
->mem_ref
)
937 if (operand_equal_p (val
->mem_ref
, rhs
, 0))
940 /* If RHS is extracting REALPART_EXPR or IMAGPART_EXPR of a
941 complex type with a known constant value, return it. */
942 if ((TREE_CODE (rhs
) == REALPART_EXPR
943 || TREE_CODE (rhs
) == IMAGPART_EXPR
)
944 && operand_equal_p (val
->mem_ref
, TREE_OPERAND (rhs
, 0), 0))
945 return fold_build1 (TREE_CODE (rhs
), TREE_TYPE (rhs
), val
->value
);
950 /* Unary operators. Note that we know the single operand must
951 be a constant. So this should almost always return a
953 if (kind
== tcc_unary
)
955 /* Handle unary operators which can appear in GIMPLE form. */
956 tree op0
= TREE_OPERAND (rhs
, 0);
958 /* Simplify the operand down to a constant. */
959 if (TREE_CODE (op0
) == SSA_NAME
)
961 prop_value_t
*val
= get_value (op0
);
962 if (val
->lattice_val
== CONSTANT
)
963 op0
= get_value (op0
)->value
;
966 if ((code
== NOP_EXPR
|| code
== CONVERT_EXPR
)
967 && useless_type_conversion_p (TREE_TYPE (rhs
), TREE_TYPE (op0
)))
969 return fold_unary_ignore_overflow (code
, TREE_TYPE (rhs
), op0
);
972 /* Binary and comparison operators. We know one or both of the
973 operands are constants. */
974 else if (kind
== tcc_binary
975 || kind
== tcc_comparison
976 || code
== TRUTH_AND_EXPR
977 || code
== TRUTH_OR_EXPR
978 || code
== TRUTH_XOR_EXPR
)
980 /* Handle binary and comparison operators that can appear in
982 tree op0
= TREE_OPERAND (rhs
, 0);
983 tree op1
= TREE_OPERAND (rhs
, 1);
985 /* Simplify the operands down to constants when appropriate. */
986 if (TREE_CODE (op0
) == SSA_NAME
)
988 prop_value_t
*val
= get_value (op0
);
989 if (val
->lattice_val
== CONSTANT
)
993 if (TREE_CODE (op1
) == SSA_NAME
)
995 prop_value_t
*val
= get_value (op1
);
996 if (val
->lattice_val
== CONSTANT
)
1000 return fold_binary (code
, TREE_TYPE (rhs
), op0
, op1
);
1003 /* We may be able to fold away calls to builtin functions if their
1004 arguments are constants. */
1005 else if (code
== CALL_EXPR
1006 && TREE_CODE (CALL_EXPR_FN (rhs
)) == ADDR_EXPR
1007 && TREE_CODE (TREE_OPERAND (CALL_EXPR_FN (rhs
), 0)) == FUNCTION_DECL
1008 && DECL_BUILT_IN (TREE_OPERAND (CALL_EXPR_FN (rhs
), 0)))
1010 if (!ZERO_SSA_OPERANDS (stmt
, SSA_OP_USE
))
1015 use_operand_p var_p
;
1017 /* Preserve the original values of every operand. */
1018 orig
= XNEWVEC (tree
, NUM_SSA_OPERANDS (stmt
, SSA_OP_USE
));
1019 FOR_EACH_SSA_TREE_OPERAND (var
, stmt
, iter
, SSA_OP_USE
)
1022 /* Substitute operands with their values and try to fold. */
1023 replace_uses_in (stmt
, NULL
, const_val
);
1024 retval
= fold_call_expr (rhs
, false);
1026 /* Restore operands to their original form. */
1028 FOR_EACH_SSA_USE_OPERAND (var_p
, stmt
, iter
, SSA_OP_USE
)
1029 SET_USE (var_p
, orig
[i
++]);
1036 /* If we got a simplified form, see if we need to convert its type. */
1038 return fold_convert (TREE_TYPE (rhs
), retval
);
1040 /* No simplification was possible. */
1045 /* Return the tree representing the element referenced by T if T is an
1046 ARRAY_REF or COMPONENT_REF into constant aggregates. Return
1047 NULL_TREE otherwise. */
1050 fold_const_aggregate_ref (tree t
)
1052 prop_value_t
*value
;
1053 tree base
, ctor
, idx
, field
;
1054 unsigned HOST_WIDE_INT cnt
;
1057 switch (TREE_CODE (t
))
1060 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1061 DECL_INITIAL. If BASE is a nested reference into another
1062 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1063 the inner reference. */
1064 base
= TREE_OPERAND (t
, 0);
1065 switch (TREE_CODE (base
))
1068 if (!TREE_READONLY (base
)
1069 || TREE_CODE (TREE_TYPE (base
)) != ARRAY_TYPE
1070 || !targetm
.binds_local_p (base
))
1073 ctor
= DECL_INITIAL (base
);
1078 ctor
= fold_const_aggregate_ref (base
);
1085 if (ctor
== NULL_TREE
1086 || (TREE_CODE (ctor
) != CONSTRUCTOR
1087 && TREE_CODE (ctor
) != STRING_CST
)
1088 || !TREE_STATIC (ctor
))
1091 /* Get the index. If we have an SSA_NAME, try to resolve it
1092 with the current lattice value for the SSA_NAME. */
1093 idx
= TREE_OPERAND (t
, 1);
1094 switch (TREE_CODE (idx
))
1097 if ((value
= get_value (idx
))
1098 && value
->lattice_val
== CONSTANT
1099 && TREE_CODE (value
->value
) == INTEGER_CST
)
1112 /* Fold read from constant string. */
1113 if (TREE_CODE (ctor
) == STRING_CST
)
1115 if ((TYPE_MODE (TREE_TYPE (t
))
1116 == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor
))))
1117 && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor
))))
1119 && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor
)))) == 1
1120 && compare_tree_int (idx
, TREE_STRING_LENGTH (ctor
)) < 0)
1121 return build_int_cst_type (TREE_TYPE (t
),
1122 (TREE_STRING_POINTER (ctor
)
1123 [TREE_INT_CST_LOW (idx
)]));
1127 /* Whoo-hoo! I'll fold ya baby. Yeah! */
1128 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor
), cnt
, cfield
, cval
)
1129 if (tree_int_cst_equal (cfield
, idx
))
1134 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1135 DECL_INITIAL. If BASE is a nested reference into another
1136 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1137 the inner reference. */
1138 base
= TREE_OPERAND (t
, 0);
1139 switch (TREE_CODE (base
))
1142 if (!TREE_READONLY (base
)
1143 || TREE_CODE (TREE_TYPE (base
)) != RECORD_TYPE
1144 || !targetm
.binds_local_p (base
))
1147 ctor
= DECL_INITIAL (base
);
1152 ctor
= fold_const_aggregate_ref (base
);
1159 if (ctor
== NULL_TREE
1160 || TREE_CODE (ctor
) != CONSTRUCTOR
1161 || !TREE_STATIC (ctor
))
1164 field
= TREE_OPERAND (t
, 1);
1166 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor
), cnt
, cfield
, cval
)
1168 /* FIXME: Handle bit-fields. */
1169 && ! DECL_BIT_FIELD (cfield
))
1176 tree c
= fold_const_aggregate_ref (TREE_OPERAND (t
, 0));
1177 if (c
&& TREE_CODE (c
) == COMPLEX_CST
)
1178 return fold_build1 (TREE_CODE (t
), TREE_TYPE (t
), c
);
1189 /* Evaluate statement STMT. */
1192 evaluate_stmt (tree stmt
)
1195 tree simplified
= NULL_TREE
;
1196 ccp_lattice_t likelyvalue
= likely_value (stmt
);
1199 val
.mem_ref
= NULL_TREE
;
1201 fold_defer_overflow_warnings ();
1203 /* If the statement is likely to have a CONSTANT result, then try
1204 to fold the statement to determine the constant value. */
1205 if (likelyvalue
== CONSTANT
)
1206 simplified
= ccp_fold (stmt
);
1207 /* If the statement is likely to have a VARYING result, then do not
1208 bother folding the statement. */
1209 if (likelyvalue
== VARYING
)
1210 simplified
= get_rhs (stmt
);
1211 /* If the statement is an ARRAY_REF or COMPONENT_REF into constant
1212 aggregates, extract the referenced constant. Otherwise the
1213 statement is likely to have an UNDEFINED value, and there will be
1214 nothing to do. Note that fold_const_aggregate_ref returns
1215 NULL_TREE if the first case does not match. */
1216 else if (!simplified
)
1217 simplified
= fold_const_aggregate_ref (get_rhs (stmt
));
1219 is_constant
= simplified
&& is_gimple_min_invariant (simplified
);
1221 fold_undefer_overflow_warnings (is_constant
, stmt
, 0);
1225 /* The statement produced a constant value. */
1226 val
.lattice_val
= CONSTANT
;
1227 val
.value
= simplified
;
1231 /* The statement produced a nonconstant value. If the statement
1232 had UNDEFINED operands, then the result of the statement
1233 should be UNDEFINED. Otherwise, the statement is VARYING. */
1234 if (likelyvalue
== UNDEFINED
)
1235 val
.lattice_val
= likelyvalue
;
1237 val
.lattice_val
= VARYING
;
1239 val
.value
= NULL_TREE
;
1246 /* Visit the assignment statement STMT. Set the value of its LHS to the
1247 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
1248 creates virtual definitions, set the value of each new name to that
1249 of the RHS (if we can derive a constant out of the RHS). */
1251 static enum ssa_prop_result
1252 visit_assignment (tree stmt
, tree
*output_p
)
1256 enum ssa_prop_result retval
;
1258 lhs
= GIMPLE_STMT_OPERAND (stmt
, 0);
1259 rhs
= GIMPLE_STMT_OPERAND (stmt
, 1);
1261 if (TREE_CODE (rhs
) == SSA_NAME
)
1263 /* For a simple copy operation, we copy the lattice values. */
1264 prop_value_t
*nval
= get_value (rhs
);
1267 else if (do_store_ccp
&& stmt_makes_single_load (stmt
))
1269 /* Same as above, but the RHS is not a gimple register and yet
1270 has a known VUSE. If STMT is loading from the same memory
1271 location that created the SSA_NAMEs for the virtual operands,
1272 we can propagate the value on the RHS. */
1273 prop_value_t
*nval
= get_value_loaded_by (stmt
, const_val
);
1277 && operand_equal_p (nval
->mem_ref
, rhs
, 0))
1280 val
= evaluate_stmt (stmt
);
1283 /* Evaluate the statement. */
1284 val
= evaluate_stmt (stmt
);
1286 /* If the original LHS was a VIEW_CONVERT_EXPR, modify the constant
1287 value to be a VIEW_CONVERT_EXPR of the old constant value.
1289 ??? Also, if this was a definition of a bitfield, we need to widen
1290 the constant value into the type of the destination variable. This
1291 should not be necessary if GCC represented bitfields properly. */
1293 tree orig_lhs
= GIMPLE_STMT_OPERAND (stmt
, 0);
1295 if (TREE_CODE (orig_lhs
) == VIEW_CONVERT_EXPR
1296 && val
.lattice_val
== CONSTANT
)
1298 tree w
= fold_unary (VIEW_CONVERT_EXPR
,
1299 TREE_TYPE (TREE_OPERAND (orig_lhs
, 0)),
1302 orig_lhs
= TREE_OPERAND (orig_lhs
, 0);
1303 if (w
&& is_gimple_min_invariant (w
))
1307 val
.lattice_val
= VARYING
;
1312 if (val
.lattice_val
== CONSTANT
1313 && TREE_CODE (orig_lhs
) == COMPONENT_REF
1314 && DECL_BIT_FIELD (TREE_OPERAND (orig_lhs
, 1)))
1316 tree w
= widen_bitfield (val
.value
, TREE_OPERAND (orig_lhs
, 1),
1319 if (w
&& is_gimple_min_invariant (w
))
1323 val
.lattice_val
= VARYING
;
1324 val
.value
= NULL_TREE
;
1325 val
.mem_ref
= NULL_TREE
;
1330 retval
= SSA_PROP_NOT_INTERESTING
;
1332 /* Set the lattice value of the statement's output. */
1333 if (TREE_CODE (lhs
) == SSA_NAME
)
1335 /* If STMT is an assignment to an SSA_NAME, we only have one
1337 if (set_lattice_value (lhs
, val
))
1340 if (val
.lattice_val
== VARYING
)
1341 retval
= SSA_PROP_VARYING
;
1343 retval
= SSA_PROP_INTERESTING
;
1346 else if (do_store_ccp
&& stmt_makes_single_store (stmt
))
1348 /* Otherwise, set the names in VDEF operands to the new
1349 constant value and mark the LHS as the memory reference
1350 associated with VAL. */
1355 /* Mark VAL as stored in the LHS of this assignment. */
1356 if (val
.lattice_val
== CONSTANT
)
1359 /* Set the value of every VDEF to VAL. */
1361 FOR_EACH_SSA_TREE_OPERAND (vdef
, stmt
, i
, SSA_OP_VIRTUAL_DEFS
)
1363 /* See PR 29801. We may have VDEFs for read-only variables
1364 (see the handling of unmodifiable variables in
1365 add_virtual_operand); do not attempt to change their value. */
1366 if (get_symbol_constant_value (SSA_NAME_VAR (vdef
)) != NULL_TREE
)
1369 changed
|= set_lattice_value (vdef
, val
);
1372 /* Note that for propagation purposes, we are only interested in
1373 visiting statements that load the exact same memory reference
1374 stored here. Those statements will have the exact same list
1375 of virtual uses, so it is enough to set the output of this
1376 statement to be its first virtual definition. */
1377 *output_p
= first_vdef (stmt
);
1380 if (val
.lattice_val
== VARYING
)
1381 retval
= SSA_PROP_VARYING
;
1383 retval
= SSA_PROP_INTERESTING
;
1391 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
1392 if it can determine which edge will be taken. Otherwise, return
1393 SSA_PROP_VARYING. */
1395 static enum ssa_prop_result
1396 visit_cond_stmt (tree stmt
, edge
*taken_edge_p
)
1401 block
= bb_for_stmt (stmt
);
1402 val
= evaluate_stmt (stmt
);
1404 /* Find which edge out of the conditional block will be taken and add it
1405 to the worklist. If no single edge can be determined statically,
1406 return SSA_PROP_VARYING to feed all the outgoing edges to the
1407 propagation engine. */
1408 *taken_edge_p
= val
.value
? find_taken_edge (block
, val
.value
) : 0;
1410 return SSA_PROP_INTERESTING
;
1412 return SSA_PROP_VARYING
;
1416 /* Evaluate statement STMT. If the statement produces an output value and
1417 its evaluation changes the lattice value of its output, return
1418 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
1421 If STMT is a conditional branch and we can determine its truth
1422 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
1423 value, return SSA_PROP_VARYING. */
1425 static enum ssa_prop_result
1426 ccp_visit_stmt (tree stmt
, edge
*taken_edge_p
, tree
*output_p
)
1431 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1433 fprintf (dump_file
, "\nVisiting statement:\n");
1434 print_generic_stmt (dump_file
, stmt
, dump_flags
);
1435 fprintf (dump_file
, "\n");
1438 if (TREE_CODE (stmt
) == GIMPLE_MODIFY_STMT
)
1440 /* If the statement is an assignment that produces a single
1441 output value, evaluate its RHS to see if the lattice value of
1442 its output has changed. */
1443 return visit_assignment (stmt
, output_p
);
1445 else if (TREE_CODE (stmt
) == COND_EXPR
|| TREE_CODE (stmt
) == SWITCH_EXPR
)
1447 /* If STMT is a conditional branch, see if we can determine
1448 which branch will be taken. */
1449 return visit_cond_stmt (stmt
, taken_edge_p
);
1452 /* Any other kind of statement is not interesting for constant
1453 propagation and, therefore, not worth simulating. */
1454 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1455 fprintf (dump_file
, "No interesting values produced. Marked VARYING.\n");
1457 /* Definitions made by statements other than assignments to
1458 SSA_NAMEs represent unknown modifications to their outputs.
1459 Mark them VARYING. */
1460 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
1462 prop_value_t v
= { VARYING
, NULL_TREE
, NULL_TREE
};
1463 set_lattice_value (def
, v
);
1466 return SSA_PROP_VARYING
;
1470 /* Main entry point for SSA Conditional Constant Propagation. */
1473 execute_ssa_ccp (bool store_ccp
)
1475 do_store_ccp
= store_ccp
;
1477 ssa_propagate (ccp_visit_stmt
, ccp_visit_phi_node
);
1478 if (ccp_finalize ())
1479 return (TODO_cleanup_cfg
| TODO_update_ssa
| TODO_remove_unused_locals
);
1488 return execute_ssa_ccp (false);
1495 return flag_tree_ccp
!= 0;
1499 struct tree_opt_pass pass_ccp
=
1502 gate_ccp
, /* gate */
1503 do_ssa_ccp
, /* execute */
1506 0, /* static_pass_number */
1507 TV_TREE_CCP
, /* tv_id */
1508 PROP_cfg
| PROP_ssa
, /* properties_required */
1509 0, /* properties_provided */
1510 0, /* properties_destroyed */
1511 0, /* todo_flags_start */
1512 TODO_dump_func
| TODO_verify_ssa
1513 | TODO_verify_stmts
| TODO_ggc_collect
,/* todo_flags_finish */
1519 do_ssa_store_ccp (void)
1521 /* If STORE-CCP is not enabled, we just run regular CCP. */
1522 return execute_ssa_ccp (flag_tree_store_ccp
!= 0);
1526 gate_store_ccp (void)
1528 /* STORE-CCP is enabled only with -ftree-store-ccp, but when
1529 -fno-tree-store-ccp is specified, we should run regular CCP.
1530 That's why the pass is enabled with either flag. */
1531 return flag_tree_store_ccp
!= 0 || flag_tree_ccp
!= 0;
1535 struct tree_opt_pass pass_store_ccp
=
1537 "store_ccp", /* name */
1538 gate_store_ccp
, /* gate */
1539 do_ssa_store_ccp
, /* execute */
1542 0, /* static_pass_number */
1543 TV_TREE_STORE_CCP
, /* tv_id */
1544 PROP_cfg
| PROP_ssa
| PROP_alias
, /* properties_required */
1545 0, /* properties_provided */
1546 0, /* properties_destroyed */
1547 0, /* todo_flags_start */
1548 TODO_dump_func
| TODO_verify_ssa
1549 | TODO_verify_stmts
| TODO_ggc_collect
,/* todo_flags_finish */
1553 /* Given a constant value VAL for bitfield FIELD, and a destination
1554 variable VAR, return VAL appropriately widened to fit into VAR. If
1555 FIELD is wider than HOST_WIDE_INT, NULL is returned. */
1558 widen_bitfield (tree val
, tree field
, tree var
)
1560 unsigned HOST_WIDE_INT var_size
, field_size
;
1562 unsigned HOST_WIDE_INT mask
;
1565 /* We can only do this if the size of the type and field and VAL are
1566 all constants representable in HOST_WIDE_INT. */
1567 if (!host_integerp (TYPE_SIZE (TREE_TYPE (var
)), 1)
1568 || !host_integerp (DECL_SIZE (field
), 1)
1569 || !host_integerp (val
, 0))
1572 var_size
= tree_low_cst (TYPE_SIZE (TREE_TYPE (var
)), 1);
1573 field_size
= tree_low_cst (DECL_SIZE (field
), 1);
1575 /* Give up if either the bitfield or the variable are too wide. */
1576 if (field_size
> HOST_BITS_PER_WIDE_INT
|| var_size
> HOST_BITS_PER_WIDE_INT
)
1579 gcc_assert (var_size
>= field_size
);
1581 /* If the sign bit of the value is not set or the field's type is unsigned,
1582 just mask off the high order bits of the value. */
1583 if (DECL_UNSIGNED (field
)
1584 || !(tree_low_cst (val
, 0) & (((HOST_WIDE_INT
)1) << (field_size
- 1))))
1586 /* Zero extension. Build a mask with the lower 'field_size' bits
1587 set and a BIT_AND_EXPR node to clear the high order bits of
1589 for (i
= 0, mask
= 0; i
< field_size
; i
++)
1590 mask
|= ((HOST_WIDE_INT
) 1) << i
;
1592 wide_val
= fold_build2 (BIT_AND_EXPR
, TREE_TYPE (var
), val
,
1593 build_int_cst (TREE_TYPE (var
), mask
));
1597 /* Sign extension. Create a mask with the upper 'field_size'
1598 bits set and a BIT_IOR_EXPR to set the high order bits of the
1600 for (i
= 0, mask
= 0; i
< (var_size
- field_size
); i
++)
1601 mask
|= ((HOST_WIDE_INT
) 1) << (var_size
- i
- 1);
1603 wide_val
= fold_build2 (BIT_IOR_EXPR
, TREE_TYPE (var
), val
,
1604 build_int_cst (TREE_TYPE (var
), mask
));
1611 /* A subroutine of fold_stmt_r. Attempts to fold *(A+O) to A[X].
1612 BASE is an array type. OFFSET is a byte displacement. ORIG_TYPE
1613 is the desired result type. */
1616 maybe_fold_offset_to_array_ref (tree base
, tree offset
, tree orig_type
,
1617 bool allow_negative_idx
)
1619 tree min_idx
, idx
, idx_type
, elt_offset
= integer_zero_node
;
1620 tree array_type
, elt_type
, elt_size
;
1623 /* If BASE is an ARRAY_REF, we can pick up another offset (this time
1624 measured in units of the size of elements type) from that ARRAY_REF).
1625 We can't do anything if either is variable.
1627 The case we handle here is *(&A[N]+O). */
1628 if (TREE_CODE (base
) == ARRAY_REF
)
1630 tree low_bound
= array_ref_low_bound (base
);
1632 elt_offset
= TREE_OPERAND (base
, 1);
1633 if (TREE_CODE (low_bound
) != INTEGER_CST
1634 || TREE_CODE (elt_offset
) != INTEGER_CST
)
1637 elt_offset
= int_const_binop (MINUS_EXPR
, elt_offset
, low_bound
, 0);
1638 base
= TREE_OPERAND (base
, 0);
1641 /* Ignore stupid user tricks of indexing non-array variables. */
1642 array_type
= TREE_TYPE (base
);
1643 if (TREE_CODE (array_type
) != ARRAY_TYPE
)
1645 elt_type
= TREE_TYPE (array_type
);
1646 if (!useless_type_conversion_p (orig_type
, elt_type
))
1649 /* Use signed size type for intermediate computation on the index. */
1650 idx_type
= signed_type_for (size_type_node
);
1652 /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the
1653 element type (so we can use the alignment if it's not constant).
1654 Otherwise, compute the offset as an index by using a division. If the
1655 division isn't exact, then don't do anything. */
1656 elt_size
= TYPE_SIZE_UNIT (elt_type
);
1659 if (integer_zerop (offset
))
1661 if (TREE_CODE (elt_size
) != INTEGER_CST
)
1662 elt_size
= size_int (TYPE_ALIGN (elt_type
));
1664 idx
= build_int_cst (idx_type
, 0);
1668 unsigned HOST_WIDE_INT lquo
, lrem
;
1669 HOST_WIDE_INT hquo
, hrem
;
1672 /* The final array offset should be signed, so we need
1673 to sign-extend the (possibly pointer) offset here
1674 and use signed division. */
1675 soffset
= double_int_sext (tree_to_double_int (offset
),
1676 TYPE_PRECISION (TREE_TYPE (offset
)));
1677 if (TREE_CODE (elt_size
) != INTEGER_CST
1678 || div_and_round_double (TRUNC_DIV_EXPR
, 0,
1679 soffset
.low
, soffset
.high
,
1680 TREE_INT_CST_LOW (elt_size
),
1681 TREE_INT_CST_HIGH (elt_size
),
1682 &lquo
, &hquo
, &lrem
, &hrem
)
1686 idx
= build_int_cst_wide (idx_type
, lquo
, hquo
);
1689 /* Assume the low bound is zero. If there is a domain type, get the
1690 low bound, if any, convert the index into that type, and add the
1692 min_idx
= build_int_cst (idx_type
, 0);
1693 domain_type
= TYPE_DOMAIN (array_type
);
1696 idx_type
= domain_type
;
1697 if (TYPE_MIN_VALUE (idx_type
))
1698 min_idx
= TYPE_MIN_VALUE (idx_type
);
1700 min_idx
= fold_convert (idx_type
, min_idx
);
1702 if (TREE_CODE (min_idx
) != INTEGER_CST
)
1705 elt_offset
= fold_convert (idx_type
, elt_offset
);
1708 if (!integer_zerop (min_idx
))
1709 idx
= int_const_binop (PLUS_EXPR
, idx
, min_idx
, 0);
1710 if (!integer_zerop (elt_offset
))
1711 idx
= int_const_binop (PLUS_EXPR
, idx
, elt_offset
, 0);
1713 /* Make sure to possibly truncate late after offsetting. */
1714 idx
= fold_convert (idx_type
, idx
);
1716 /* We don't want to construct access past array bounds. For example
1719 should not be simplified into (*c)[14] or tree-vrp will
1720 give false warnings. The same is true for
1721 struct A { long x; char d[0]; } *a;
1723 which should be not folded to &a->d[-8]. */
1725 && TYPE_MAX_VALUE (domain_type
)
1726 && TREE_CODE (TYPE_MAX_VALUE (domain_type
)) == INTEGER_CST
)
1728 tree up_bound
= TYPE_MAX_VALUE (domain_type
);
1730 if (tree_int_cst_lt (up_bound
, idx
)
1731 /* Accesses after the end of arrays of size 0 (gcc
1732 extension) and 1 are likely intentional ("struct
1734 && compare_tree_int (up_bound
, 1) > 0)
1738 && TYPE_MIN_VALUE (domain_type
))
1740 if (!allow_negative_idx
1741 && TREE_CODE (TYPE_MIN_VALUE (domain_type
)) == INTEGER_CST
1742 && tree_int_cst_lt (idx
, TYPE_MIN_VALUE (domain_type
)))
1745 else if (!allow_negative_idx
1746 && compare_tree_int (idx
, 0) < 0)
1749 return build4 (ARRAY_REF
, elt_type
, base
, idx
, NULL_TREE
, NULL_TREE
);
1753 /* Attempt to fold *(S+O) to S.X.
1754 BASE is a record type. OFFSET is a byte displacement. ORIG_TYPE
1755 is the desired result type. */
1758 maybe_fold_offset_to_component_ref (tree record_type
, tree base
, tree offset
,
1759 tree orig_type
, bool base_is_ptr
)
1761 tree f
, t
, field_type
, tail_array_field
, field_offset
;
1765 if (TREE_CODE (record_type
) != RECORD_TYPE
1766 && TREE_CODE (record_type
) != UNION_TYPE
1767 && TREE_CODE (record_type
) != QUAL_UNION_TYPE
)
1770 /* Short-circuit silly cases. */
1771 if (useless_type_conversion_p (record_type
, orig_type
))
1774 tail_array_field
= NULL_TREE
;
1775 for (f
= TYPE_FIELDS (record_type
); f
; f
= TREE_CHAIN (f
))
1779 if (TREE_CODE (f
) != FIELD_DECL
)
1781 if (DECL_BIT_FIELD (f
))
1784 if (!DECL_FIELD_OFFSET (f
))
1786 field_offset
= byte_position (f
);
1787 if (TREE_CODE (field_offset
) != INTEGER_CST
)
1790 /* ??? Java creates "interesting" fields for representing base classes.
1791 They have no name, and have no context. With no context, we get into
1792 trouble with nonoverlapping_component_refs_p. Skip them. */
1793 if (!DECL_FIELD_CONTEXT (f
))
1796 /* The previous array field isn't at the end. */
1797 tail_array_field
= NULL_TREE
;
1799 /* Check to see if this offset overlaps with the field. */
1800 cmp
= tree_int_cst_compare (field_offset
, offset
);
1804 field_type
= TREE_TYPE (f
);
1806 /* Here we exactly match the offset being checked. If the types match,
1807 then we can return that field. */
1809 && useless_type_conversion_p (orig_type
, field_type
))
1812 base
= build1 (INDIRECT_REF
, record_type
, base
);
1813 t
= build3 (COMPONENT_REF
, field_type
, base
, f
, NULL_TREE
);
1817 /* Don't care about offsets into the middle of scalars. */
1818 if (!AGGREGATE_TYPE_P (field_type
))
1821 /* Check for array at the end of the struct. This is often
1822 used as for flexible array members. We should be able to
1823 turn this into an array access anyway. */
1824 if (TREE_CODE (field_type
) == ARRAY_TYPE
)
1825 tail_array_field
= f
;
1827 /* Check the end of the field against the offset. */
1828 if (!DECL_SIZE_UNIT (f
)
1829 || TREE_CODE (DECL_SIZE_UNIT (f
)) != INTEGER_CST
)
1831 t
= int_const_binop (MINUS_EXPR
, offset
, field_offset
, 1);
1832 if (!tree_int_cst_lt (t
, DECL_SIZE_UNIT (f
)))
1835 /* If we matched, then set offset to the displacement into
1838 new_base
= build1 (INDIRECT_REF
, record_type
, base
);
1841 new_base
= build3 (COMPONENT_REF
, field_type
, new_base
, f
, NULL_TREE
);
1843 /* Recurse to possibly find the match. */
1844 ret
= maybe_fold_offset_to_array_ref (new_base
, t
, orig_type
,
1845 f
== TYPE_FIELDS (record_type
));
1848 ret
= maybe_fold_offset_to_component_ref (field_type
, new_base
, t
,
1854 if (!tail_array_field
)
1857 f
= tail_array_field
;
1858 field_type
= TREE_TYPE (f
);
1859 offset
= int_const_binop (MINUS_EXPR
, offset
, byte_position (f
), 1);
1861 /* If we get here, we've got an aggregate field, and a possibly
1862 nonzero offset into them. Recurse and hope for a valid match. */
1864 base
= build1 (INDIRECT_REF
, record_type
, base
);
1865 base
= build3 (COMPONENT_REF
, field_type
, base
, f
, NULL_TREE
);
1867 t
= maybe_fold_offset_to_array_ref (base
, offset
, orig_type
,
1868 f
== TYPE_FIELDS (record_type
));
1871 return maybe_fold_offset_to_component_ref (field_type
, base
, offset
,
1875 /* Attempt to express (ORIG_TYPE)BASE+OFFSET as BASE->field_of_orig_type
1876 or BASE[index] or by combination of those.
1878 Before attempting the conversion strip off existing ADDR_EXPRs and
1879 handled component refs. */
1882 maybe_fold_offset_to_reference (tree base
, tree offset
, tree orig_type
)
1886 bool base_is_ptr
= true;
1889 if (TREE_CODE (base
) == ADDR_EXPR
)
1891 base_is_ptr
= false;
1893 base
= TREE_OPERAND (base
, 0);
1895 /* Handle case where existing COMPONENT_REF pick e.g. wrong field of union,
1896 so it needs to be removed and new COMPONENT_REF constructed.
1897 The wrong COMPONENT_REF are often constructed by folding the
1898 (type *)&object within the expression (type *)&object+offset */
1899 if (handled_component_p (base
) && 0)
1901 HOST_WIDE_INT sub_offset
, size
, maxsize
;
1903 newbase
= get_ref_base_and_extent (base
, &sub_offset
,
1905 gcc_assert (newbase
);
1906 gcc_assert (!(sub_offset
& (BITS_PER_UNIT
- 1)));
1907 if (size
== maxsize
)
1911 offset
= int_const_binop (PLUS_EXPR
, offset
,
1912 build_int_cst (TREE_TYPE (offset
),
1913 sub_offset
/ BITS_PER_UNIT
), 1);
1916 if (useless_type_conversion_p (orig_type
, TREE_TYPE (base
))
1917 && integer_zerop (offset
))
1919 type
= TREE_TYPE (base
);
1924 if (!POINTER_TYPE_P (TREE_TYPE (base
)))
1926 type
= TREE_TYPE (TREE_TYPE (base
));
1928 ret
= maybe_fold_offset_to_component_ref (type
, base
, offset
,
1929 orig_type
, base_is_ptr
);
1933 base
= build1 (INDIRECT_REF
, type
, base
);
1934 ret
= maybe_fold_offset_to_array_ref (base
, offset
, orig_type
, true);
1939 /* A subroutine of fold_stmt_r. Attempt to simplify *(BASE+OFFSET).
1940 Return the simplified expression, or NULL if nothing could be done. */
1943 maybe_fold_stmt_indirect (tree expr
, tree base
, tree offset
)
1946 bool volatile_p
= TREE_THIS_VOLATILE (expr
);
1948 /* We may well have constructed a double-nested PLUS_EXPR via multiple
1949 substitutions. Fold that down to one. Remove NON_LVALUE_EXPRs that
1950 are sometimes added. */
1952 STRIP_TYPE_NOPS (base
);
1953 TREE_OPERAND (expr
, 0) = base
;
1955 /* One possibility is that the address reduces to a string constant. */
1956 t
= fold_read_from_constant_string (expr
);
1960 /* Add in any offset from a POINTER_PLUS_EXPR. */
1961 if (TREE_CODE (base
) == POINTER_PLUS_EXPR
)
1965 offset2
= TREE_OPERAND (base
, 1);
1966 if (TREE_CODE (offset2
) != INTEGER_CST
)
1968 base
= TREE_OPERAND (base
, 0);
1970 offset
= fold_convert (sizetype
,
1971 int_const_binop (PLUS_EXPR
, offset
, offset2
, 1));
1974 if (TREE_CODE (base
) == ADDR_EXPR
)
1976 tree base_addr
= base
;
1978 /* Strip the ADDR_EXPR. */
1979 base
= TREE_OPERAND (base
, 0);
1981 /* Fold away CONST_DECL to its value, if the type is scalar. */
1982 if (TREE_CODE (base
) == CONST_DECL
1983 && ccp_decl_initial_min_invariant (DECL_INITIAL (base
)))
1984 return DECL_INITIAL (base
);
1986 /* Try folding *(&B+O) to B.X. */
1987 t
= maybe_fold_offset_to_reference (base_addr
, offset
,
1991 TREE_THIS_VOLATILE (t
) = volatile_p
;
1997 /* We can get here for out-of-range string constant accesses,
1998 such as "_"[3]. Bail out of the entire substitution search
1999 and arrange for the entire statement to be replaced by a
2000 call to __builtin_trap. In all likelihood this will all be
2001 constant-folded away, but in the meantime we can't leave with
2002 something that get_expr_operands can't understand. */
2006 if (TREE_CODE (t
) == ADDR_EXPR
2007 && TREE_CODE (TREE_OPERAND (t
, 0)) == STRING_CST
)
2009 /* FIXME: Except that this causes problems elsewhere with dead
2010 code not being deleted, and we die in the rtl expanders
2011 because we failed to remove some ssa_name. In the meantime,
2012 just return zero. */
2013 /* FIXME2: This condition should be signaled by
2014 fold_read_from_constant_string directly, rather than
2015 re-checking for it here. */
2016 return integer_zero_node
;
2019 /* Try folding *(B+O) to B->X. Still an improvement. */
2020 if (POINTER_TYPE_P (TREE_TYPE (base
)))
2022 t
= maybe_fold_offset_to_reference (base
, offset
,
2029 /* Otherwise we had an offset that we could not simplify. */
2034 /* A subroutine of fold_stmt_r. EXPR is a POINTER_PLUS_EXPR.
2036 A quaint feature extant in our address arithmetic is that there
2037 can be hidden type changes here. The type of the result need
2038 not be the same as the type of the input pointer.
2040 What we're after here is an expression of the form
2041 (T *)(&array + const)
2042 where the cast doesn't actually exist, but is implicit in the
2043 type of the POINTER_PLUS_EXPR. We'd like to turn this into
2045 which may be able to propagate further. */
2048 maybe_fold_stmt_addition (tree expr
)
2050 tree op0
= TREE_OPERAND (expr
, 0);
2051 tree op1
= TREE_OPERAND (expr
, 1);
2052 tree ptr_type
= TREE_TYPE (expr
);
2056 gcc_assert (TREE_CODE (expr
) == POINTER_PLUS_EXPR
);
2058 /* It had better be a constant. */
2059 if (TREE_CODE (op1
) != INTEGER_CST
)
2061 /* The first operand should be an ADDR_EXPR. */
2062 if (TREE_CODE (op0
) != ADDR_EXPR
)
2064 op0
= TREE_OPERAND (op0
, 0);
2066 /* If the first operand is an ARRAY_REF, expand it so that we can fold
2067 the offset into it. */
2068 while (TREE_CODE (op0
) == ARRAY_REF
)
2070 tree array_obj
= TREE_OPERAND (op0
, 0);
2071 tree array_idx
= TREE_OPERAND (op0
, 1);
2072 tree elt_type
= TREE_TYPE (op0
);
2073 tree elt_size
= TYPE_SIZE_UNIT (elt_type
);
2076 if (TREE_CODE (array_idx
) != INTEGER_CST
)
2078 if (TREE_CODE (elt_size
) != INTEGER_CST
)
2081 /* Un-bias the index by the min index of the array type. */
2082 min_idx
= TYPE_DOMAIN (TREE_TYPE (array_obj
));
2085 min_idx
= TYPE_MIN_VALUE (min_idx
);
2088 if (TREE_CODE (min_idx
) != INTEGER_CST
)
2091 array_idx
= fold_convert (TREE_TYPE (min_idx
), array_idx
);
2092 if (!integer_zerop (min_idx
))
2093 array_idx
= int_const_binop (MINUS_EXPR
, array_idx
,
2098 /* Convert the index to a byte offset. */
2099 array_idx
= fold_convert (sizetype
, array_idx
);
2100 array_idx
= int_const_binop (MULT_EXPR
, array_idx
, elt_size
, 0);
2102 /* Update the operands for the next round, or for folding. */
2103 op1
= int_const_binop (PLUS_EXPR
,
2108 ptd_type
= TREE_TYPE (ptr_type
);
2110 /* At which point we can try some of the same things as for indirects. */
2111 t
= maybe_fold_offset_to_array_ref (op0
, op1
, ptd_type
, true);
2113 t
= maybe_fold_offset_to_component_ref (TREE_TYPE (op0
), op0
, op1
,
2116 t
= build1 (ADDR_EXPR
, ptr_type
, t
);
2121 /* For passing state through walk_tree into fold_stmt_r and its
2124 struct fold_stmt_r_data
2128 bool *inside_addr_expr_p
;
2131 /* Subroutine of fold_stmt called via walk_tree. We perform several
2132 simplifications of EXPR_P, mostly having to do with pointer arithmetic. */
2135 fold_stmt_r (tree
*expr_p
, int *walk_subtrees
, void *data
)
2137 struct fold_stmt_r_data
*fold_stmt_r_data
= (struct fold_stmt_r_data
*) data
;
2138 bool *inside_addr_expr_p
= fold_stmt_r_data
->inside_addr_expr_p
;
2139 bool *changed_p
= fold_stmt_r_data
->changed_p
;
2140 tree expr
= *expr_p
, t
;
2141 bool volatile_p
= TREE_THIS_VOLATILE (expr
);
2143 /* ??? It'd be nice if walk_tree had a pre-order option. */
2144 switch (TREE_CODE (expr
))
2147 t
= walk_tree (&TREE_OPERAND (expr
, 0), fold_stmt_r
, data
, NULL
);
2152 t
= maybe_fold_stmt_indirect (expr
, TREE_OPERAND (expr
, 0),
2157 t
= walk_tree (&TREE_OPERAND (expr
, 0), fold_stmt_r
, data
, NULL
);
2162 if (POINTER_TYPE_P (TREE_TYPE (expr
))
2163 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (expr
, 0)))
2164 && (t
= maybe_fold_offset_to_reference
2165 (TREE_OPERAND (expr
, 0),
2167 TREE_TYPE (TREE_TYPE (expr
)))))
2169 tree ptr_type
= build_pointer_type (TREE_TYPE (t
));
2170 if (!useless_type_conversion_p (TREE_TYPE (expr
), ptr_type
))
2172 t
= build_fold_addr_expr_with_type (t
, ptr_type
);
2176 /* ??? Could handle more ARRAY_REFs here, as a variant of INDIRECT_REF.
2177 We'd only want to bother decomposing an existing ARRAY_REF if
2178 the base array is found to have another offset contained within.
2179 Otherwise we'd be wasting time. */
2181 /* If we are not processing expressions found within an
2182 ADDR_EXPR, then we can fold constant array references. */
2183 if (!*inside_addr_expr_p
)
2184 t
= fold_read_from_constant_string (expr
);
2190 *inside_addr_expr_p
= true;
2191 t
= walk_tree (&TREE_OPERAND (expr
, 0), fold_stmt_r
, data
, NULL
);
2192 *inside_addr_expr_p
= false;
2197 /* Set TREE_INVARIANT properly so that the value is properly
2198 considered constant, and so gets propagated as expected. */
2200 recompute_tree_invariant_for_addr_expr (expr
);
2203 case POINTER_PLUS_EXPR
:
2204 t
= walk_tree (&TREE_OPERAND (expr
, 0), fold_stmt_r
, data
, NULL
);
2207 t
= walk_tree (&TREE_OPERAND (expr
, 1), fold_stmt_r
, data
, NULL
);
2212 t
= maybe_fold_stmt_addition (expr
);
2216 t
= walk_tree (&TREE_OPERAND (expr
, 0), fold_stmt_r
, data
, NULL
);
2221 /* Make sure the FIELD_DECL is actually a field in the type on the lhs.
2222 We've already checked that the records are compatible, so we should
2223 come up with a set of compatible fields. */
2225 tree expr_record
= TREE_TYPE (TREE_OPERAND (expr
, 0));
2226 tree expr_field
= TREE_OPERAND (expr
, 1);
2228 if (DECL_FIELD_CONTEXT (expr_field
) != TYPE_MAIN_VARIANT (expr_record
))
2230 expr_field
= find_compatible_field (expr_record
, expr_field
);
2231 TREE_OPERAND (expr
, 1) = expr_field
;
2236 case TARGET_MEM_REF
:
2237 t
= maybe_fold_tmr (expr
);
2241 if (COMPARISON_CLASS_P (TREE_OPERAND (expr
, 0)))
2243 tree op0
= TREE_OPERAND (expr
, 0);
2247 fold_defer_overflow_warnings ();
2248 tem
= fold_binary (TREE_CODE (op0
), TREE_TYPE (op0
),
2249 TREE_OPERAND (op0
, 0),
2250 TREE_OPERAND (op0
, 1));
2251 set
= tem
&& set_rhs (expr_p
, tem
);
2252 fold_undefer_overflow_warnings (set
, fold_stmt_r_data
->stmt
, 0);
2267 /* Preserve volatileness of the original expression. */
2268 TREE_THIS_VOLATILE (t
) = volatile_p
;
2277 /* Return the string length, maximum string length or maximum value of
2279 If ARG is an SSA name variable, follow its use-def chains. If LENGTH
2280 is not NULL and, for TYPE == 0, its value is not equal to the length
2281 we determine or if we are unable to determine the length or value,
2282 return false. VISITED is a bitmap of visited variables.
2283 TYPE is 0 if string length should be returned, 1 for maximum string
2284 length and 2 for maximum value ARG can have. */
2287 get_maxval_strlen (tree arg
, tree
*length
, bitmap visited
, int type
)
2289 tree var
, def_stmt
, val
;
2291 if (TREE_CODE (arg
) != SSA_NAME
)
2293 if (TREE_CODE (arg
) == COND_EXPR
)
2294 return get_maxval_strlen (COND_EXPR_THEN (arg
), length
, visited
, type
)
2295 && get_maxval_strlen (COND_EXPR_ELSE (arg
), length
, visited
, type
);
2300 if (TREE_CODE (val
) != INTEGER_CST
2301 || tree_int_cst_sgn (val
) < 0)
2305 val
= c_strlen (arg
, 1);
2313 if (TREE_CODE (*length
) != INTEGER_CST
2314 || TREE_CODE (val
) != INTEGER_CST
)
2317 if (tree_int_cst_lt (*length
, val
))
2321 else if (simple_cst_equal (val
, *length
) != 1)
2329 /* If we were already here, break the infinite cycle. */
2330 if (bitmap_bit_p (visited
, SSA_NAME_VERSION (arg
)))
2332 bitmap_set_bit (visited
, SSA_NAME_VERSION (arg
));
2335 def_stmt
= SSA_NAME_DEF_STMT (var
);
2337 switch (TREE_CODE (def_stmt
))
2339 case GIMPLE_MODIFY_STMT
:
2343 /* The RHS of the statement defining VAR must either have a
2344 constant length or come from another SSA_NAME with a constant
2346 rhs
= GIMPLE_STMT_OPERAND (def_stmt
, 1);
2348 return get_maxval_strlen (rhs
, length
, visited
, type
);
2353 /* All the arguments of the PHI node must have the same constant
2357 for (i
= 0; i
< PHI_NUM_ARGS (def_stmt
); i
++)
2359 tree arg
= PHI_ARG_DEF (def_stmt
, i
);
2361 /* If this PHI has itself as an argument, we cannot
2362 determine the string length of this argument. However,
2363 if we can find a constant string length for the other
2364 PHI args then we can still be sure that this is a
2365 constant string length. So be optimistic and just
2366 continue with the next argument. */
2367 if (arg
== PHI_RESULT (def_stmt
))
2370 if (!get_maxval_strlen (arg
, length
, visited
, type
))
2386 /* Fold builtin call FN in statement STMT. If it cannot be folded into a
2387 constant, return NULL_TREE. Otherwise, return its constant value. */
2390 ccp_fold_builtin (tree stmt
, tree fn
)
2392 tree result
, val
[3];
2394 int arg_mask
, i
, type
;
2397 call_expr_arg_iterator iter
;
2400 ignore
= TREE_CODE (stmt
) != GIMPLE_MODIFY_STMT
;
2402 /* First try the generic builtin folder. If that succeeds, return the
2404 result
= fold_call_expr (fn
, ignore
);
2408 STRIP_NOPS (result
);
2412 /* Ignore MD builtins. */
2413 callee
= get_callee_fndecl (fn
);
2414 if (DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_MD
)
2417 /* If the builtin could not be folded, and it has no argument list,
2419 nargs
= call_expr_nargs (fn
);
2423 /* Limit the work only for builtins we know how to simplify. */
2424 switch (DECL_FUNCTION_CODE (callee
))
2426 case BUILT_IN_STRLEN
:
2427 case BUILT_IN_FPUTS
:
2428 case BUILT_IN_FPUTS_UNLOCKED
:
2432 case BUILT_IN_STRCPY
:
2433 case BUILT_IN_STRNCPY
:
2437 case BUILT_IN_MEMCPY_CHK
:
2438 case BUILT_IN_MEMPCPY_CHK
:
2439 case BUILT_IN_MEMMOVE_CHK
:
2440 case BUILT_IN_MEMSET_CHK
:
2441 case BUILT_IN_STRNCPY_CHK
:
2445 case BUILT_IN_STRCPY_CHK
:
2446 case BUILT_IN_STPCPY_CHK
:
2450 case BUILT_IN_SNPRINTF_CHK
:
2451 case BUILT_IN_VSNPRINTF_CHK
:
2459 /* Try to use the dataflow information gathered by the CCP process. */
2460 visited
= BITMAP_ALLOC (NULL
);
2462 memset (val
, 0, sizeof (val
));
2463 init_call_expr_arg_iterator (fn
, &iter
);
2464 for (i
= 0; arg_mask
; i
++, arg_mask
>>= 1)
2466 a
= next_call_expr_arg (&iter
);
2469 bitmap_clear (visited
);
2470 if (!get_maxval_strlen (a
, &val
[i
], visited
, type
))
2475 BITMAP_FREE (visited
);
2478 switch (DECL_FUNCTION_CODE (callee
))
2480 case BUILT_IN_STRLEN
:
2481 if (val
[0] && nargs
== 1)
2483 tree new_val
= fold_convert (TREE_TYPE (fn
), val
[0]);
2485 /* If the result is not a valid gimple value, or not a cast
2486 of a valid gimple value, then we can not use the result. */
2487 if (is_gimple_val (new_val
)
2488 || (is_gimple_cast (new_val
)
2489 && is_gimple_val (TREE_OPERAND (new_val
, 0))))
2494 case BUILT_IN_STRCPY
:
2495 if (val
[1] && is_gimple_val (val
[1]) && nargs
== 2)
2496 result
= fold_builtin_strcpy (callee
,
2497 CALL_EXPR_ARG (fn
, 0),
2498 CALL_EXPR_ARG (fn
, 1),
2502 case BUILT_IN_STRNCPY
:
2503 if (val
[1] && is_gimple_val (val
[1]) && nargs
== 3)
2504 result
= fold_builtin_strncpy (callee
,
2505 CALL_EXPR_ARG (fn
, 0),
2506 CALL_EXPR_ARG (fn
, 1),
2507 CALL_EXPR_ARG (fn
, 2),
2511 case BUILT_IN_FPUTS
:
2513 result
= fold_builtin_fputs (CALL_EXPR_ARG (fn
, 0),
2514 CALL_EXPR_ARG (fn
, 1),
2515 TREE_CODE (stmt
) != GIMPLE_MODIFY_STMT
, 0,
2519 case BUILT_IN_FPUTS_UNLOCKED
:
2521 result
= fold_builtin_fputs (CALL_EXPR_ARG (fn
, 0),
2522 CALL_EXPR_ARG (fn
, 1),
2523 TREE_CODE (stmt
) != GIMPLE_MODIFY_STMT
, 1,
2527 case BUILT_IN_MEMCPY_CHK
:
2528 case BUILT_IN_MEMPCPY_CHK
:
2529 case BUILT_IN_MEMMOVE_CHK
:
2530 case BUILT_IN_MEMSET_CHK
:
2531 if (val
[2] && is_gimple_val (val
[2]) && nargs
== 4)
2532 result
= fold_builtin_memory_chk (callee
,
2533 CALL_EXPR_ARG (fn
, 0),
2534 CALL_EXPR_ARG (fn
, 1),
2535 CALL_EXPR_ARG (fn
, 2),
2536 CALL_EXPR_ARG (fn
, 3),
2538 DECL_FUNCTION_CODE (callee
));
2541 case BUILT_IN_STRCPY_CHK
:
2542 case BUILT_IN_STPCPY_CHK
:
2543 if (val
[1] && is_gimple_val (val
[1]) && nargs
== 3)
2544 result
= fold_builtin_stxcpy_chk (callee
,
2545 CALL_EXPR_ARG (fn
, 0),
2546 CALL_EXPR_ARG (fn
, 1),
2547 CALL_EXPR_ARG (fn
, 2),
2549 DECL_FUNCTION_CODE (callee
));
2552 case BUILT_IN_STRNCPY_CHK
:
2553 if (val
[2] && is_gimple_val (val
[2]) && nargs
== 4)
2554 result
= fold_builtin_strncpy_chk (CALL_EXPR_ARG (fn
, 0),
2555 CALL_EXPR_ARG (fn
, 1),
2556 CALL_EXPR_ARG (fn
, 2),
2557 CALL_EXPR_ARG (fn
, 3),
2561 case BUILT_IN_SNPRINTF_CHK
:
2562 case BUILT_IN_VSNPRINTF_CHK
:
2563 if (val
[1] && is_gimple_val (val
[1]))
2564 result
= fold_builtin_snprintf_chk (fn
, val
[1],
2565 DECL_FUNCTION_CODE (callee
));
2572 if (result
&& ignore
)
2573 result
= fold_ignored_result (result
);
2578 /* Fold the statement pointed to by STMT_P. In some cases, this function may
2579 replace the whole statement with a new one. Returns true iff folding
2580 makes any changes. */
2583 fold_stmt (tree
*stmt_p
)
2585 tree rhs
, result
, stmt
;
2586 struct fold_stmt_r_data fold_stmt_r_data
;
2587 bool changed
= false;
2588 bool inside_addr_expr
= false;
2592 fold_stmt_r_data
.stmt
= stmt
;
2593 fold_stmt_r_data
.changed_p
= &changed
;
2594 fold_stmt_r_data
.inside_addr_expr_p
= &inside_addr_expr
;
2596 /* If we replaced constants and the statement makes pointer dereferences,
2597 then we may need to fold instances of *&VAR into VAR, etc. */
2598 if (walk_tree (stmt_p
, fold_stmt_r
, &fold_stmt_r_data
, NULL
))
2600 *stmt_p
= build_call_expr (implicit_built_in_decls
[BUILT_IN_TRAP
], 0);
2604 rhs
= get_rhs (stmt
);
2609 if (TREE_CODE (rhs
) == CALL_EXPR
)
2613 /* Check for builtins that CCP can handle using information not
2614 available in the generic fold routines. */
2615 callee
= get_callee_fndecl (rhs
);
2616 if (callee
&& DECL_BUILT_IN (callee
))
2617 result
= ccp_fold_builtin (stmt
, rhs
);
2620 /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve
2621 here are when we've propagated the address of a decl into the
2623 /* ??? Should perhaps do this in fold proper. However, doing it
2624 there requires that we create a new CALL_EXPR, and that requires
2625 copying EH region info to the new node. Easier to just do it
2626 here where we can just smash the call operand. Also
2627 CALL_EXPR_RETURN_SLOT_OPT needs to be handled correctly and
2628 copied, fold_call_expr does not have not information. */
2629 callee
= CALL_EXPR_FN (rhs
);
2630 if (TREE_CODE (callee
) == OBJ_TYPE_REF
2631 && lang_hooks
.fold_obj_type_ref
2632 && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee
)) == ADDR_EXPR
2633 && DECL_P (TREE_OPERAND
2634 (OBJ_TYPE_REF_OBJECT (callee
), 0)))
2638 /* ??? Caution: Broken ADDR_EXPR semantics means that
2639 looking at the type of the operand of the addr_expr
2640 can yield an array type. See silly exception in
2641 check_pointer_types_r. */
2643 t
= TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee
)));
2644 t
= lang_hooks
.fold_obj_type_ref (callee
, t
);
2647 CALL_EXPR_FN (rhs
) = t
;
2653 else if (TREE_CODE (rhs
) == COND_EXPR
)
2655 tree temp
= fold (COND_EXPR_COND (rhs
));
2656 if (temp
!= COND_EXPR_COND (rhs
))
2657 result
= fold_build3 (COND_EXPR
, TREE_TYPE (rhs
), temp
,
2658 COND_EXPR_THEN (rhs
), COND_EXPR_ELSE (rhs
));
2661 /* If we couldn't fold the RHS, hand over to the generic fold routines. */
2662 if (result
== NULL_TREE
)
2663 result
= fold (rhs
);
2665 /* Strip away useless type conversions. Both the NON_LVALUE_EXPR that
2666 may have been added by fold, and "useless" type conversions that might
2667 now be apparent due to propagation. */
2668 STRIP_USELESS_TYPE_CONVERSION (result
);
2671 changed
|= set_rhs (stmt_p
, result
);
2676 /* Perform the minimal folding on statement STMT. Only operations like
2677 *&x created by constant propagation are handled. The statement cannot
2678 be replaced with a new one. */
2681 fold_stmt_inplace (tree stmt
)
2683 tree old_stmt
= stmt
, rhs
, new_rhs
;
2684 struct fold_stmt_r_data fold_stmt_r_data
;
2685 bool changed
= false;
2686 bool inside_addr_expr
= false;
2688 fold_stmt_r_data
.stmt
= stmt
;
2689 fold_stmt_r_data
.changed_p
= &changed
;
2690 fold_stmt_r_data
.inside_addr_expr_p
= &inside_addr_expr
;
2692 walk_tree (&stmt
, fold_stmt_r
, &fold_stmt_r_data
, NULL
);
2693 gcc_assert (stmt
== old_stmt
);
2695 rhs
= get_rhs (stmt
);
2696 if (!rhs
|| rhs
== stmt
)
2699 new_rhs
= fold (rhs
);
2700 STRIP_USELESS_TYPE_CONVERSION (new_rhs
);
2704 changed
|= set_rhs (&stmt
, new_rhs
);
2705 gcc_assert (stmt
== old_stmt
);
2710 /* Try to optimize out __builtin_stack_restore. Optimize it out
2711 if there is another __builtin_stack_restore in the same basic
2712 block and no calls or ASM_EXPRs are in between, or if this block's
2713 only outgoing edge is to EXIT_BLOCK and there are no calls or
2714 ASM_EXPRs after this __builtin_stack_restore. */
2717 optimize_stack_restore (basic_block bb
, tree call
, block_stmt_iterator i
)
2719 tree stack_save
, stmt
, callee
;
2721 if (TREE_CODE (call
) != CALL_EXPR
2722 || call_expr_nargs (call
) != 1
2723 || TREE_CODE (CALL_EXPR_ARG (call
, 0)) != SSA_NAME
2724 || !POINTER_TYPE_P (TREE_TYPE (CALL_EXPR_ARG (call
, 0))))
2727 for (bsi_next (&i
); !bsi_end_p (i
); bsi_next (&i
))
2731 stmt
= bsi_stmt (i
);
2732 if (TREE_CODE (stmt
) == ASM_EXPR
)
2734 call
= get_call_expr_in (stmt
);
2738 callee
= get_callee_fndecl (call
);
2740 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2741 /* All regular builtins are ok, just obviously not alloca. */
2742 || DECL_FUNCTION_CODE (callee
) == BUILT_IN_ALLOCA
)
2745 if (DECL_FUNCTION_CODE (callee
) == BUILT_IN_STACK_RESTORE
)
2750 && (! single_succ_p (bb
)
2751 || single_succ_edge (bb
)->dest
!= EXIT_BLOCK_PTR
))
2754 stack_save
= SSA_NAME_DEF_STMT (CALL_EXPR_ARG (call
, 0));
2755 if (TREE_CODE (stack_save
) != GIMPLE_MODIFY_STMT
2756 || GIMPLE_STMT_OPERAND (stack_save
, 0) != CALL_EXPR_ARG (call
, 0)
2757 || TREE_CODE (GIMPLE_STMT_OPERAND (stack_save
, 1)) != CALL_EXPR
2758 || tree_could_throw_p (stack_save
)
2759 || !has_single_use (CALL_EXPR_ARG (call
, 0)))
2762 callee
= get_callee_fndecl (GIMPLE_STMT_OPERAND (stack_save
, 1));
2764 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2765 || DECL_FUNCTION_CODE (callee
) != BUILT_IN_STACK_SAVE
2766 || call_expr_nargs (GIMPLE_STMT_OPERAND (stack_save
, 1)) != 0)
2770 push_stmt_changes (&stmt
);
2771 if (!set_rhs (&stmt
,
2772 build_int_cst (TREE_TYPE (CALL_EXPR_ARG (call
, 0)), 0)))
2774 discard_stmt_changes (&stmt
);
2777 gcc_assert (stmt
== stack_save
);
2778 pop_stmt_changes (&stmt
);
2780 return integer_zero_node
;
2783 /* If va_list type is a simple pointer and nothing special is needed,
2784 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
2785 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
2786 pointer assignment. */
2789 optimize_stdarg_builtin (tree call
)
2791 tree callee
, lhs
, rhs
;
2792 bool va_list_simple_ptr
;
2794 if (TREE_CODE (call
) != CALL_EXPR
)
2797 va_list_simple_ptr
= POINTER_TYPE_P (va_list_type_node
)
2798 && (TREE_TYPE (va_list_type_node
) == void_type_node
2799 || TREE_TYPE (va_list_type_node
) == char_type_node
);
2801 callee
= get_callee_fndecl (call
);
2802 switch (DECL_FUNCTION_CODE (callee
))
2804 case BUILT_IN_VA_START
:
2805 if (!va_list_simple_ptr
2806 || targetm
.expand_builtin_va_start
!= NULL
2807 || built_in_decls
[BUILT_IN_NEXT_ARG
] == NULL
)
2810 if (call_expr_nargs (call
) != 2)
2813 lhs
= CALL_EXPR_ARG (call
, 0);
2814 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2815 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2816 != TYPE_MAIN_VARIANT (va_list_type_node
))
2819 lhs
= build_fold_indirect_ref (lhs
);
2820 rhs
= build_call_expr (built_in_decls
[BUILT_IN_NEXT_ARG
],
2821 1, integer_zero_node
);
2822 rhs
= fold_convert (TREE_TYPE (lhs
), rhs
);
2823 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2825 case BUILT_IN_VA_COPY
:
2826 if (!va_list_simple_ptr
)
2829 if (call_expr_nargs (call
) != 2)
2832 lhs
= CALL_EXPR_ARG (call
, 0);
2833 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2834 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2835 != TYPE_MAIN_VARIANT (va_list_type_node
))
2838 lhs
= build_fold_indirect_ref (lhs
);
2839 rhs
= CALL_EXPR_ARG (call
, 1);
2840 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs
))
2841 != TYPE_MAIN_VARIANT (va_list_type_node
))
2844 rhs
= fold_convert (TREE_TYPE (lhs
), rhs
);
2845 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2847 case BUILT_IN_VA_END
:
2848 return integer_zero_node
;
2855 /* Convert EXPR into a GIMPLE value suitable for substitution on the
2856 RHS of an assignment. Insert the necessary statements before
2858 When IGNORE is set, don't worry about the return value. */
2861 convert_to_gimple_builtin (block_stmt_iterator
*si_p
, tree expr
, bool ignore
)
2863 tree_stmt_iterator ti
;
2864 tree stmt
= bsi_stmt (*si_p
);
2865 tree tmp
, stmts
= NULL
;
2867 push_gimplify_context ();
2870 tmp
= build_empty_stmt ();
2871 gimplify_and_add (expr
, &stmts
);
2874 tmp
= get_initialized_tmp_var (expr
, &stmts
, NULL
);
2875 pop_gimplify_context (NULL
);
2877 if (EXPR_HAS_LOCATION (stmt
))
2878 annotate_all_with_locus (&stmts
, EXPR_LOCATION (stmt
));
2880 /* The replacement can expose previously unreferenced variables. */
2881 for (ti
= tsi_start (stmts
); !tsi_end_p (ti
); tsi_next (&ti
))
2883 tree new_stmt
= tsi_stmt (ti
);
2884 find_new_referenced_vars (tsi_stmt_ptr (ti
));
2885 bsi_insert_before (si_p
, new_stmt
, BSI_NEW_STMT
);
2886 mark_symbols_for_renaming (new_stmt
);
2894 /* A simple pass that attempts to fold all builtin functions. This pass
2895 is run after we've propagated as many constants as we can. */
2898 execute_fold_all_builtins (void)
2900 bool cfg_changed
= false;
2902 unsigned int todoflags
= 0;
2906 block_stmt_iterator i
;
2907 for (i
= bsi_start (bb
); !bsi_end_p (i
); )
2909 tree
*stmtp
= bsi_stmt_ptr (i
);
2910 tree old_stmt
= *stmtp
;
2911 tree call
= get_rhs (*stmtp
);
2912 tree callee
, result
;
2913 enum built_in_function fcode
;
2915 if (!call
|| TREE_CODE (call
) != CALL_EXPR
)
2920 callee
= get_callee_fndecl (call
);
2921 if (!callee
|| DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
)
2926 fcode
= DECL_FUNCTION_CODE (callee
);
2928 result
= ccp_fold_builtin (*stmtp
, call
);
2931 gimple_remove_stmt_histograms (cfun
, *stmtp
);
2934 switch (DECL_FUNCTION_CODE (callee
))
2936 case BUILT_IN_CONSTANT_P
:
2937 /* Resolve __builtin_constant_p. If it hasn't been
2938 folded to integer_one_node by now, it's fairly
2939 certain that the value simply isn't constant. */
2940 result
= integer_zero_node
;
2943 case BUILT_IN_STACK_RESTORE
:
2944 result
= optimize_stack_restore (bb
, *stmtp
, i
);
2950 case BUILT_IN_VA_START
:
2951 case BUILT_IN_VA_END
:
2952 case BUILT_IN_VA_COPY
:
2953 /* These shouldn't be folded before pass_stdarg. */
2954 result
= optimize_stdarg_builtin (*stmtp
);
2964 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2966 fprintf (dump_file
, "Simplified\n ");
2967 print_generic_stmt (dump_file
, *stmtp
, dump_flags
);
2970 push_stmt_changes (stmtp
);
2972 if (!set_rhs (stmtp
, result
))
2974 result
= convert_to_gimple_builtin (&i
, result
,
2975 TREE_CODE (old_stmt
)
2976 != GIMPLE_MODIFY_STMT
);
2979 bool ok
= set_rhs (stmtp
, result
);
2981 todoflags
|= TODO_rebuild_alias
;
2985 pop_stmt_changes (stmtp
);
2987 if (maybe_clean_or_replace_eh_stmt (old_stmt
, *stmtp
)
2988 && tree_purge_dead_eh_edges (bb
))
2991 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2993 fprintf (dump_file
, "to\n ");
2994 print_generic_stmt (dump_file
, *stmtp
, dump_flags
);
2995 fprintf (dump_file
, "\n");
2998 /* Retry the same statement if it changed into another
2999 builtin, there might be new opportunities now. */
3000 call
= get_rhs (*stmtp
);
3001 if (!call
|| TREE_CODE (call
) != CALL_EXPR
)
3006 callee
= get_callee_fndecl (call
);
3008 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
3009 || DECL_FUNCTION_CODE (callee
) == fcode
)
3014 /* Delete unreachable blocks. */
3016 todoflags
|= TODO_cleanup_cfg
;
3022 struct tree_opt_pass pass_fold_builtins
=
3026 execute_fold_all_builtins
, /* execute */
3029 0, /* static_pass_number */
3031 PROP_cfg
| PROP_ssa
, /* properties_required */
3032 0, /* properties_provided */
3033 0, /* properties_destroyed */
3034 0, /* todo_flags_start */
3037 | TODO_update_ssa
, /* todo_flags_finish */