1 /* Conditional constant propagation pass for the GNU compiler.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
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"
214 /* Possible lattice values. */
223 /* Array of propagated constant values. After propagation,
224 CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If
225 the constant is held in an SSA name representing a memory store
226 (i.e., a VDEF), CONST_VAL[I].MEM_REF will contain the actual
227 memory reference used to store (i.e., the LHS of the assignment
229 static prop_value_t *const_val;
231 static void canonicalize_float_value (prop_value_t *);
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");
272 /* If SYM is a constant variable with known value, return the value.
273 NULL_TREE is returned otherwise. */
276 get_symbol_constant_value (tree sym)
278 if (TREE_STATIC (sym)
279 && TREE_READONLY (sym))
281 tree val = DECL_INITIAL (sym);
284 STRIP_USELESS_TYPE_CONVERSION (val);
285 if (is_gimple_min_invariant (val))
287 if (TREE_CODE (val) == ADDR_EXPR)
289 tree base = get_base_address (TREE_OPERAND (val, 0));
290 if (base && TREE_CODE (base) == VAR_DECL)
291 add_referenced_var (base);
296 /* Variables declared 'const' without an initializer
297 have zero as the initializer if they may not be
298 overridden at link or run time. */
300 && !DECL_EXTERNAL (sym)
301 && targetm.binds_local_p (sym)
302 && (INTEGRAL_TYPE_P (TREE_TYPE (sym))
303 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (sym))))
304 return fold_convert (TREE_TYPE (sym), integer_zero_node);
310 /* Compute a default value for variable VAR and store it in the
311 CONST_VAL array. The following rules are used to get default
314 1- Global and static variables that are declared constant are
317 2- Any other value is considered UNDEFINED. This is useful when
318 considering PHI nodes. PHI arguments that are undefined do not
319 change the constant value of the PHI node, which allows for more
320 constants to be propagated.
322 3- Variables defined by statements other than assignments and PHI
323 nodes are considered VARYING.
325 4- Initial values of variables that are not GIMPLE registers are
326 considered VARYING. */
329 get_default_value (tree var)
331 tree sym = SSA_NAME_VAR (var);
332 prop_value_t val = { UNINITIALIZED, NULL_TREE };
335 stmt = SSA_NAME_DEF_STMT (var);
337 if (gimple_nop_p (stmt))
339 /* Variables defined by an empty statement are those used
340 before being initialized. If VAR is a local variable, we
341 can assume initially that it is UNDEFINED, otherwise we must
342 consider it VARYING. */
343 if (is_gimple_reg (sym) && TREE_CODE (sym) != PARM_DECL)
344 val.lattice_val = UNDEFINED;
346 val.lattice_val = VARYING;
348 else if (is_gimple_assign (stmt)
349 /* Value-returning GIMPLE_CALL statements assign to
350 a variable, and are treated similarly to GIMPLE_ASSIGN. */
351 || (is_gimple_call (stmt)
352 && gimple_call_lhs (stmt) != NULL_TREE)
353 || gimple_code (stmt) == GIMPLE_PHI)
356 if (gimple_assign_single_p (stmt)
357 && DECL_P (gimple_assign_rhs1 (stmt))
358 && (cst = get_symbol_constant_value (gimple_assign_rhs1 (stmt))))
360 val.lattice_val = CONSTANT;
364 /* Any other variable defined by an assignment or a PHI node
365 is considered UNDEFINED. */
366 val.lattice_val = UNDEFINED;
370 /* Otherwise, VAR will never take on a constant value. */
371 val.lattice_val = VARYING;
378 /* Get the constant value associated with variable VAR. */
380 static inline prop_value_t *
385 if (const_val == NULL)
388 val = &const_val[SSA_NAME_VERSION (var)];
389 if (val->lattice_val == UNINITIALIZED)
390 *val = get_default_value (var);
392 canonicalize_float_value (val);
397 /* Sets the value associated with VAR to VARYING. */
400 set_value_varying (tree var)
402 prop_value_t *val = &const_val[SSA_NAME_VERSION (var)];
404 val->lattice_val = VARYING;
405 val->value = NULL_TREE;
408 /* For float types, modify the value of VAL to make ccp work correctly
409 for non-standard values (-0, NaN):
411 If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0.
412 If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED.
413 This is to fix the following problem (see PR 29921): Suppose we have
417 and we set value of y to NaN. This causes value of x to be set to NaN.
418 When we later determine that y is in fact VARYING, fold uses the fact
419 that HONOR_NANS is false, and we try to change the value of x to 0,
420 causing an ICE. With HONOR_NANS being false, the real appearance of
421 NaN would cause undefined behavior, though, so claiming that y (and x)
422 are UNDEFINED initially is correct. */
425 canonicalize_float_value (prop_value_t *val)
427 enum machine_mode mode;
431 if (val->lattice_val != CONSTANT
432 || TREE_CODE (val->value) != REAL_CST)
435 d = TREE_REAL_CST (val->value);
436 type = TREE_TYPE (val->value);
437 mode = TYPE_MODE (type);
439 if (!HONOR_SIGNED_ZEROS (mode)
440 && REAL_VALUE_MINUS_ZERO (d))
442 val->value = build_real (type, dconst0);
446 if (!HONOR_NANS (mode)
447 && REAL_VALUE_ISNAN (d))
449 val->lattice_val = UNDEFINED;
455 /* Set the value for variable VAR to NEW_VAL. Return true if the new
456 value is different from VAR's previous value. */
459 set_lattice_value (tree var, prop_value_t new_val)
461 prop_value_t *old_val = get_value (var);
463 canonicalize_float_value (&new_val);
465 /* Lattice transitions must always be monotonically increasing in
466 value. If *OLD_VAL and NEW_VAL are the same, return false to
467 inform the caller that this was a non-transition. */
469 gcc_assert (old_val->lattice_val < new_val.lattice_val
470 || (old_val->lattice_val == new_val.lattice_val
471 && ((!old_val->value && !new_val.value)
472 || operand_equal_p (old_val->value, new_val.value, 0))));
474 if (old_val->lattice_val != new_val.lattice_val)
476 if (dump_file && (dump_flags & TDF_DETAILS))
478 dump_lattice_value (dump_file, "Lattice value changed to ", new_val);
479 fprintf (dump_file, ". Adding SSA edges to worklist.\n");
484 gcc_assert (new_val.lattice_val != UNDEFINED);
492 /* Return the likely CCP lattice value for STMT.
494 If STMT has no operands, then return CONSTANT.
496 Else if undefinedness of operands of STMT cause its value to be
497 undefined, then return UNDEFINED.
499 Else if any operands of STMT are constants, then return CONSTANT.
501 Else return VARYING. */
504 likely_value (gimple stmt)
506 bool has_constant_operand, has_undefined_operand, all_undefined_operands;
511 enum gimple_code code = gimple_code (stmt);
513 /* This function appears to be called only for assignments, calls,
514 conditionals, and switches, due to the logic in visit_stmt. */
515 gcc_assert (code == GIMPLE_ASSIGN
516 || code == GIMPLE_CALL
517 || code == GIMPLE_COND
518 || code == GIMPLE_SWITCH);
520 /* If the statement has volatile operands, it won't fold to a
522 if (gimple_has_volatile_ops (stmt))
525 /* Arrive here for more complex cases. */
526 has_constant_operand = false;
527 has_undefined_operand = false;
528 all_undefined_operands = true;
529 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE)
531 prop_value_t *val = get_value (use);
533 if (val->lattice_val == UNDEFINED)
534 has_undefined_operand = true;
536 all_undefined_operands = false;
538 if (val->lattice_val == CONSTANT)
539 has_constant_operand = true;
542 /* There may be constants in regular rhs operands. For calls we
543 have to ignore lhs, fndecl and static chain, otherwise only
545 for (i = (is_gimple_call (stmt) ? 2 : 0) + gimple_has_lhs (stmt);
546 i < gimple_num_ops (stmt); ++i)
548 tree op = gimple_op (stmt, i);
549 if (!op || TREE_CODE (op) == SSA_NAME)
551 if (is_gimple_min_invariant (op))
552 has_constant_operand = true;
555 /* If the operation combines operands like COMPLEX_EXPR make sure to
556 not mark the result UNDEFINED if only one part of the result is
558 if (has_undefined_operand && all_undefined_operands)
560 else if (code == GIMPLE_ASSIGN && has_undefined_operand)
562 switch (gimple_assign_rhs_code (stmt))
564 /* Unary operators are handled with all_undefined_operands. */
567 case POINTER_PLUS_EXPR:
568 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected.
569 Not bitwise operators, one VARYING operand may specify the
570 result completely. Not logical operators for the same reason.
571 Not COMPLEX_EXPR as one VARYING operand makes the result partly
572 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because
573 the undefined operand may be promoted. */
580 /* If there was an UNDEFINED operand but the result may be not UNDEFINED
581 fall back to VARYING even if there were CONSTANT operands. */
582 if (has_undefined_operand)
585 /* We do not consider virtual operands here -- load from read-only
586 memory may have only VARYING virtual operands, but still be
588 if (has_constant_operand
589 || gimple_references_memory_p (stmt))
595 /* Returns true if STMT cannot be constant. */
598 surely_varying_stmt_p (gimple stmt)
600 /* If the statement has operands that we cannot handle, it cannot be
602 if (gimple_has_volatile_ops (stmt))
605 /* If it is a call and does not return a value or is not a
606 builtin and not an indirect call, it is varying. */
607 if (is_gimple_call (stmt))
610 if (!gimple_call_lhs (stmt)
611 || ((fndecl = gimple_call_fndecl (stmt)) != NULL_TREE
612 && !DECL_BUILT_IN (fndecl)))
616 /* Any other store operation is not interesting. */
617 else if (gimple_vdef (stmt))
620 /* Anything other than assignments and conditional jumps are not
621 interesting for CCP. */
622 if (gimple_code (stmt) != GIMPLE_ASSIGN
623 && gimple_code (stmt) != GIMPLE_COND
624 && gimple_code (stmt) != GIMPLE_SWITCH
625 && gimple_code (stmt) != GIMPLE_CALL)
631 /* Initialize local data structures for CCP. */
634 ccp_initialize (void)
638 const_val = XCNEWVEC (prop_value_t, num_ssa_names);
640 /* Initialize simulation flags for PHI nodes and statements. */
643 gimple_stmt_iterator i;
645 for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i))
647 gimple stmt = gsi_stmt (i);
648 bool is_varying = surely_varying_stmt_p (stmt);
655 /* If the statement will not produce a constant, mark
656 all its outputs VARYING. */
657 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
658 set_value_varying (def);
660 prop_set_simulate_again (stmt, !is_varying);
664 /* Now process PHI nodes. We never clear the simulate_again flag on
665 phi nodes, since we do not know which edges are executable yet,
666 except for phi nodes for virtual operands when we do not do store ccp. */
669 gimple_stmt_iterator i;
671 for (i = gsi_start_phis (bb); !gsi_end_p (i); gsi_next (&i))
673 gimple phi = gsi_stmt (i);
675 if (!is_gimple_reg (gimple_phi_result (phi)))
676 prop_set_simulate_again (phi, false);
678 prop_set_simulate_again (phi, true);
683 /* Debug count support. Reset the values of ssa names
684 VARYING when the total number ssa names analyzed is
685 beyond the debug count specified. */
691 for (i = 0; i < num_ssa_names; i++)
695 const_val[i].lattice_val = VARYING;
696 const_val[i].value = NULL_TREE;
702 /* Do final substitution of propagated values, cleanup the flowgraph and
703 free allocated storage.
705 Return TRUE when something was optimized. */
710 bool something_changed;
713 /* Perform substitutions based on the known constant values. */
714 something_changed = substitute_and_fold (const_val, false);
718 return something_changed;;
722 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
725 any M UNDEFINED = any
726 any M VARYING = VARYING
727 Ci M Cj = Ci if (i == j)
728 Ci M Cj = VARYING if (i != j)
732 ccp_lattice_meet (prop_value_t *val1, prop_value_t *val2)
734 if (val1->lattice_val == UNDEFINED)
736 /* UNDEFINED M any = any */
739 else if (val2->lattice_val == UNDEFINED)
741 /* any M UNDEFINED = any
742 Nothing to do. VAL1 already contains the value we want. */
745 else if (val1->lattice_val == VARYING
746 || val2->lattice_val == VARYING)
748 /* any M VARYING = VARYING. */
749 val1->lattice_val = VARYING;
750 val1->value = NULL_TREE;
752 else if (val1->lattice_val == CONSTANT
753 && val2->lattice_val == CONSTANT
754 && simple_cst_equal (val1->value, val2->value) == 1)
756 /* Ci M Cj = Ci if (i == j)
757 Ci M Cj = VARYING if (i != j)
759 If these two values come from memory stores, make sure that
760 they come from the same memory reference. */
761 val1->lattice_val = CONSTANT;
762 val1->value = val1->value;
766 /* Any other combination is VARYING. */
767 val1->lattice_val = VARYING;
768 val1->value = NULL_TREE;
773 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
774 lattice values to determine PHI_NODE's lattice value. The value of a
775 PHI node is determined calling ccp_lattice_meet with all the arguments
776 of the PHI node that are incoming via executable edges. */
778 static enum ssa_prop_result
779 ccp_visit_phi_node (gimple phi)
782 prop_value_t *old_val, new_val;
784 if (dump_file && (dump_flags & TDF_DETAILS))
786 fprintf (dump_file, "\nVisiting PHI node: ");
787 print_gimple_stmt (dump_file, phi, 0, dump_flags);
790 old_val = get_value (gimple_phi_result (phi));
791 switch (old_val->lattice_val)
794 return SSA_PROP_VARYING;
801 new_val.lattice_val = UNDEFINED;
802 new_val.value = NULL_TREE;
809 for (i = 0; i < gimple_phi_num_args (phi); i++)
811 /* Compute the meet operator over all the PHI arguments flowing
812 through executable edges. */
813 edge e = gimple_phi_arg_edge (phi, i);
815 if (dump_file && (dump_flags & TDF_DETAILS))
818 "\n Argument #%d (%d -> %d %sexecutable)\n",
819 i, e->src->index, e->dest->index,
820 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
823 /* If the incoming edge is executable, Compute the meet operator for
824 the existing value of the PHI node and the current PHI argument. */
825 if (e->flags & EDGE_EXECUTABLE)
827 tree arg = gimple_phi_arg (phi, i)->def;
828 prop_value_t arg_val;
830 if (is_gimple_min_invariant (arg))
832 arg_val.lattice_val = CONSTANT;
836 arg_val = *(get_value (arg));
838 ccp_lattice_meet (&new_val, &arg_val);
840 if (dump_file && (dump_flags & TDF_DETAILS))
842 fprintf (dump_file, "\t");
843 print_generic_expr (dump_file, arg, dump_flags);
844 dump_lattice_value (dump_file, "\tValue: ", arg_val);
845 fprintf (dump_file, "\n");
848 if (new_val.lattice_val == VARYING)
853 if (dump_file && (dump_flags & TDF_DETAILS))
855 dump_lattice_value (dump_file, "\n PHI node value: ", new_val);
856 fprintf (dump_file, "\n\n");
859 /* Make the transition to the new value. */
860 if (set_lattice_value (gimple_phi_result (phi), new_val))
862 if (new_val.lattice_val == VARYING)
863 return SSA_PROP_VARYING;
865 return SSA_PROP_INTERESTING;
868 return SSA_PROP_NOT_INTERESTING;
871 /* Return true if we may propagate the address expression ADDR into the
872 dereference DEREF and cancel them. */
875 may_propagate_address_into_dereference (tree addr, tree deref)
877 gcc_assert (INDIRECT_REF_P (deref)
878 && TREE_CODE (addr) == ADDR_EXPR);
880 /* Don't propagate if ADDR's operand has incomplete type. */
881 if (!COMPLETE_TYPE_P (TREE_TYPE (TREE_OPERAND (addr, 0))))
884 /* If the address is invariant then we do not need to preserve restrict
885 qualifications. But we do need to preserve volatile qualifiers until
886 we can annotate the folded dereference itself properly. */
887 if (is_gimple_min_invariant (addr)
888 && (!TREE_THIS_VOLATILE (deref)
889 || TYPE_VOLATILE (TREE_TYPE (addr))))
890 return useless_type_conversion_p (TREE_TYPE (deref),
891 TREE_TYPE (TREE_OPERAND (addr, 0)));
893 /* Else both the address substitution and the folding must result in
894 a valid useless type conversion sequence. */
895 return (useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (deref, 0)),
897 && useless_type_conversion_p (TREE_TYPE (deref),
898 TREE_TYPE (TREE_OPERAND (addr, 0))));
901 /* CCP specific front-end to the non-destructive constant folding
904 Attempt to simplify the RHS of STMT knowing that one or more
905 operands are constants.
907 If simplification is possible, return the simplified RHS,
908 otherwise return the original RHS or NULL_TREE. */
911 ccp_fold (gimple stmt)
913 location_t loc = gimple_location (stmt);
914 switch (gimple_code (stmt))
918 enum tree_code subcode = gimple_assign_rhs_code (stmt);
920 switch (get_gimple_rhs_class (subcode))
922 case GIMPLE_SINGLE_RHS:
924 tree rhs = gimple_assign_rhs1 (stmt);
925 enum tree_code_class kind = TREE_CODE_CLASS (subcode);
927 if (TREE_CODE (rhs) == SSA_NAME)
929 /* If the RHS is an SSA_NAME, return its known constant value,
931 return get_value (rhs)->value;
933 /* Handle propagating invariant addresses into address operations.
934 The folding we do here matches that in tree-ssa-forwprop.c. */
935 else if (TREE_CODE (rhs) == ADDR_EXPR)
938 base = &TREE_OPERAND (rhs, 0);
939 while (handled_component_p (*base))
940 base = &TREE_OPERAND (*base, 0);
941 if (TREE_CODE (*base) == INDIRECT_REF
942 && TREE_CODE (TREE_OPERAND (*base, 0)) == SSA_NAME)
944 prop_value_t *val = get_value (TREE_OPERAND (*base, 0));
945 if (val->lattice_val == CONSTANT
946 && TREE_CODE (val->value) == ADDR_EXPR
947 && may_propagate_address_into_dereference
950 /* We need to return a new tree, not modify the IL
951 or share parts of it. So play some tricks to
952 avoid manually building it. */
953 tree ret, save = *base;
954 *base = TREE_OPERAND (val->value, 0);
955 ret = unshare_expr (rhs);
956 recompute_tree_invariant_for_addr_expr (ret);
962 else if (TREE_CODE (rhs) == CONSTRUCTOR
963 && TREE_CODE (TREE_TYPE (rhs)) == VECTOR_TYPE
964 && (CONSTRUCTOR_NELTS (rhs)
965 == TYPE_VECTOR_SUBPARTS (TREE_TYPE (rhs))))
971 FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (rhs), i, val)
973 if (TREE_CODE (val) == SSA_NAME
974 && get_value (val)->lattice_val == CONSTANT)
975 val = get_value (val)->value;
976 if (TREE_CODE (val) == INTEGER_CST
977 || TREE_CODE (val) == REAL_CST
978 || TREE_CODE (val) == FIXED_CST)
979 list = tree_cons (NULL_TREE, val, list);
984 return build_vector (TREE_TYPE (rhs), nreverse (list));
987 if (kind == tcc_reference)
989 if ((TREE_CODE (rhs) == VIEW_CONVERT_EXPR
990 || TREE_CODE (rhs) == REALPART_EXPR
991 || TREE_CODE (rhs) == IMAGPART_EXPR)
992 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
994 prop_value_t *val = get_value (TREE_OPERAND (rhs, 0));
995 if (val->lattice_val == CONSTANT)
996 return fold_unary_loc (EXPR_LOCATION (rhs),
998 TREE_TYPE (rhs), val->value);
1000 else if (TREE_CODE (rhs) == INDIRECT_REF
1001 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
1003 prop_value_t *val = get_value (TREE_OPERAND (rhs, 0));
1004 if (val->lattice_val == CONSTANT
1005 && TREE_CODE (val->value) == ADDR_EXPR
1006 && useless_type_conversion_p (TREE_TYPE (rhs),
1007 TREE_TYPE (TREE_TYPE (val->value))))
1008 rhs = TREE_OPERAND (val->value, 0);
1010 return fold_const_aggregate_ref (rhs);
1012 else if (kind == tcc_declaration)
1013 return get_symbol_constant_value (rhs);
1017 case GIMPLE_UNARY_RHS:
1019 /* Handle unary operators that can appear in GIMPLE form.
1020 Note that we know the single operand must be a constant,
1021 so this should almost always return a simplified RHS. */
1022 tree lhs = gimple_assign_lhs (stmt);
1023 tree op0 = gimple_assign_rhs1 (stmt);
1025 /* Simplify the operand down to a constant. */
1026 if (TREE_CODE (op0) == SSA_NAME)
1028 prop_value_t *val = get_value (op0);
1029 if (val->lattice_val == CONSTANT)
1030 op0 = get_value (op0)->value;
1033 /* Conversions are useless for CCP purposes if they are
1034 value-preserving. Thus the restrictions that
1035 useless_type_conversion_p places for pointer type conversions
1036 do not apply here. Substitution later will only substitute to
1038 if (CONVERT_EXPR_CODE_P (subcode)
1039 && POINTER_TYPE_P (TREE_TYPE (lhs))
1040 && POINTER_TYPE_P (TREE_TYPE (op0))
1041 /* Do not allow differences in volatile qualification
1042 as this might get us confused as to whether a
1043 propagation destination statement is volatile
1044 or not. See PR36988. */
1045 && (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (lhs)))
1046 == TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (op0)))))
1049 /* Still try to generate a constant of correct type. */
1050 if (!useless_type_conversion_p (TREE_TYPE (lhs),
1052 && ((tem = maybe_fold_offset_to_address
1054 op0, integer_zero_node, TREE_TYPE (lhs)))
1061 fold_unary_ignore_overflow_loc (loc, subcode,
1062 gimple_expr_type (stmt), op0);
1065 case GIMPLE_BINARY_RHS:
1067 /* Handle binary operators that can appear in GIMPLE form. */
1068 tree op0 = gimple_assign_rhs1 (stmt);
1069 tree op1 = gimple_assign_rhs2 (stmt);
1071 /* Simplify the operands down to constants when appropriate. */
1072 if (TREE_CODE (op0) == SSA_NAME)
1074 prop_value_t *val = get_value (op0);
1075 if (val->lattice_val == CONSTANT)
1079 if (TREE_CODE (op1) == SSA_NAME)
1081 prop_value_t *val = get_value (op1);
1082 if (val->lattice_val == CONSTANT)
1086 /* Fold &foo + CST into an invariant reference if possible. */
1087 if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR
1088 && TREE_CODE (op0) == ADDR_EXPR
1089 && TREE_CODE (op1) == INTEGER_CST)
1091 tree lhs = gimple_assign_lhs (stmt);
1092 tree tem = maybe_fold_offset_to_address
1093 (loc, op0, op1, TREE_TYPE (lhs));
1094 if (tem != NULL_TREE)
1098 return fold_binary_loc (loc, subcode,
1099 gimple_expr_type (stmt), op0, op1);
1110 tree fn = gimple_call_fn (stmt);
1113 if (TREE_CODE (fn) == SSA_NAME)
1115 val = get_value (fn);
1116 if (val->lattice_val == CONSTANT)
1119 if (TREE_CODE (fn) == ADDR_EXPR
1120 && TREE_CODE (TREE_OPERAND (fn, 0)) == FUNCTION_DECL
1121 && DECL_BUILT_IN (TREE_OPERAND (fn, 0)))
1123 tree *args = XALLOCAVEC (tree, gimple_call_num_args (stmt));
1126 for (i = 0; i < gimple_call_num_args (stmt); ++i)
1128 args[i] = gimple_call_arg (stmt, i);
1129 if (TREE_CODE (args[i]) == SSA_NAME)
1131 val = get_value (args[i]);
1132 if (val->lattice_val == CONSTANT)
1133 args[i] = val->value;
1136 call = build_call_array_loc (loc,
1137 gimple_call_return_type (stmt),
1138 fn, gimple_call_num_args (stmt), args);
1139 retval = fold_call_expr (EXPR_LOCATION (call), call, false);
1141 /* fold_call_expr wraps the result inside a NOP_EXPR. */
1142 STRIP_NOPS (retval);
1150 /* Handle comparison operators that can appear in GIMPLE form. */
1151 tree op0 = gimple_cond_lhs (stmt);
1152 tree op1 = gimple_cond_rhs (stmt);
1153 enum tree_code code = gimple_cond_code (stmt);
1155 /* Simplify the operands down to constants when appropriate. */
1156 if (TREE_CODE (op0) == SSA_NAME)
1158 prop_value_t *val = get_value (op0);
1159 if (val->lattice_val == CONSTANT)
1163 if (TREE_CODE (op1) == SSA_NAME)
1165 prop_value_t *val = get_value (op1);
1166 if (val->lattice_val == CONSTANT)
1170 return fold_binary_loc (loc, code, boolean_type_node, op0, op1);
1175 tree rhs = gimple_switch_index (stmt);
1177 if (TREE_CODE (rhs) == SSA_NAME)
1179 /* If the RHS is an SSA_NAME, return its known constant value,
1181 return get_value (rhs)->value;
1193 /* Return the tree representing the element referenced by T if T is an
1194 ARRAY_REF or COMPONENT_REF into constant aggregates. Return
1195 NULL_TREE otherwise. */
1198 fold_const_aggregate_ref (tree t)
1200 prop_value_t *value;
1201 tree base, ctor, idx, field;
1202 unsigned HOST_WIDE_INT cnt;
1205 if (TREE_CODE_CLASS (TREE_CODE (t)) == tcc_declaration)
1206 return get_symbol_constant_value (t);
1208 switch (TREE_CODE (t))
1211 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1212 DECL_INITIAL. If BASE is a nested reference into another
1213 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1214 the inner reference. */
1215 base = TREE_OPERAND (t, 0);
1216 switch (TREE_CODE (base))
1219 if (!TREE_READONLY (base)
1220 || TREE_CODE (TREE_TYPE (base)) != ARRAY_TYPE
1221 || !targetm.binds_local_p (base))
1224 ctor = DECL_INITIAL (base);
1229 ctor = fold_const_aggregate_ref (base);
1241 if (ctor == NULL_TREE
1242 || (TREE_CODE (ctor) != CONSTRUCTOR
1243 && TREE_CODE (ctor) != STRING_CST)
1244 || !TREE_STATIC (ctor))
1247 /* Get the index. If we have an SSA_NAME, try to resolve it
1248 with the current lattice value for the SSA_NAME. */
1249 idx = TREE_OPERAND (t, 1);
1250 switch (TREE_CODE (idx))
1253 if ((value = get_value (idx))
1254 && value->lattice_val == CONSTANT
1255 && TREE_CODE (value->value) == INTEGER_CST)
1268 /* Fold read from constant string. */
1269 if (TREE_CODE (ctor) == STRING_CST)
1271 if ((TYPE_MODE (TREE_TYPE (t))
1272 == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1273 && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1275 && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) == 1
1276 && compare_tree_int (idx, TREE_STRING_LENGTH (ctor)) < 0)
1277 return build_int_cst_type (TREE_TYPE (t),
1278 (TREE_STRING_POINTER (ctor)
1279 [TREE_INT_CST_LOW (idx)]));
1283 /* Whoo-hoo! I'll fold ya baby. Yeah! */
1284 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
1285 if (tree_int_cst_equal (cfield, idx))
1287 STRIP_USELESS_TYPE_CONVERSION (cval);
1288 if (TREE_CODE (cval) == ADDR_EXPR)
1290 tree base = get_base_address (TREE_OPERAND (cval, 0));
1291 if (base && TREE_CODE (base) == VAR_DECL)
1292 add_referenced_var (base);
1299 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1300 DECL_INITIAL. If BASE is a nested reference into another
1301 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1302 the inner reference. */
1303 base = TREE_OPERAND (t, 0);
1304 switch (TREE_CODE (base))
1307 if (!TREE_READONLY (base)
1308 || TREE_CODE (TREE_TYPE (base)) != RECORD_TYPE
1309 || !targetm.binds_local_p (base))
1312 ctor = DECL_INITIAL (base);
1317 ctor = fold_const_aggregate_ref (base);
1324 if (ctor == NULL_TREE
1325 || TREE_CODE (ctor) != CONSTRUCTOR
1326 || !TREE_STATIC (ctor))
1329 field = TREE_OPERAND (t, 1);
1331 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
1333 /* FIXME: Handle bit-fields. */
1334 && ! DECL_BIT_FIELD (cfield))
1336 STRIP_USELESS_TYPE_CONVERSION (cval);
1337 if (TREE_CODE (cval) == ADDR_EXPR)
1339 tree base = get_base_address (TREE_OPERAND (cval, 0));
1340 if (base && TREE_CODE (base) == VAR_DECL)
1341 add_referenced_var (base);
1350 tree c = fold_const_aggregate_ref (TREE_OPERAND (t, 0));
1351 if (c && TREE_CODE (c) == COMPLEX_CST)
1352 return fold_build1_loc (EXPR_LOCATION (t),
1353 TREE_CODE (t), TREE_TYPE (t), c);
1359 tree base = TREE_OPERAND (t, 0);
1360 if (TREE_CODE (base) == SSA_NAME
1361 && (value = get_value (base))
1362 && value->lattice_val == CONSTANT
1363 && TREE_CODE (value->value) == ADDR_EXPR
1364 && useless_type_conversion_p (TREE_TYPE (t),
1365 TREE_TYPE (TREE_TYPE (value->value))))
1366 return fold_const_aggregate_ref (TREE_OPERAND (value->value, 0));
1377 /* Evaluate statement STMT.
1378 Valid only for assignments, calls, conditionals, and switches. */
1381 evaluate_stmt (gimple stmt)
1384 tree simplified = NULL_TREE;
1385 ccp_lattice_t likelyvalue = likely_value (stmt);
1388 fold_defer_overflow_warnings ();
1390 /* If the statement is likely to have a CONSTANT result, then try
1391 to fold the statement to determine the constant value. */
1392 /* FIXME. This is the only place that we call ccp_fold.
1393 Since likely_value never returns CONSTANT for calls, we will
1394 not attempt to fold them, including builtins that may profit. */
1395 if (likelyvalue == CONSTANT)
1396 simplified = ccp_fold (stmt);
1397 /* If the statement is likely to have a VARYING result, then do not
1398 bother folding the statement. */
1399 else if (likelyvalue == VARYING)
1401 enum gimple_code code = gimple_code (stmt);
1402 if (code == GIMPLE_ASSIGN)
1404 enum tree_code subcode = gimple_assign_rhs_code (stmt);
1406 /* Other cases cannot satisfy is_gimple_min_invariant
1408 if (get_gimple_rhs_class (subcode) == GIMPLE_SINGLE_RHS)
1409 simplified = gimple_assign_rhs1 (stmt);
1411 else if (code == GIMPLE_SWITCH)
1412 simplified = gimple_switch_index (stmt);
1414 /* These cannot satisfy is_gimple_min_invariant without folding. */
1415 gcc_assert (code == GIMPLE_CALL || code == GIMPLE_COND);
1418 is_constant = simplified && is_gimple_min_invariant (simplified);
1420 fold_undefer_overflow_warnings (is_constant, stmt, 0);
1422 if (dump_file && (dump_flags & TDF_DETAILS))
1424 fprintf (dump_file, "which is likely ");
1425 switch (likelyvalue)
1428 fprintf (dump_file, "CONSTANT");
1431 fprintf (dump_file, "UNDEFINED");
1434 fprintf (dump_file, "VARYING");
1438 fprintf (dump_file, "\n");
1443 /* The statement produced a constant value. */
1444 val.lattice_val = CONSTANT;
1445 val.value = simplified;
1449 /* The statement produced a nonconstant value. If the statement
1450 had UNDEFINED operands, then the result of the statement
1451 should be UNDEFINED. Otherwise, the statement is VARYING. */
1452 if (likelyvalue == UNDEFINED)
1453 val.lattice_val = likelyvalue;
1455 val.lattice_val = VARYING;
1457 val.value = NULL_TREE;
1463 /* Visit the assignment statement STMT. Set the value of its LHS to the
1464 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
1465 creates virtual definitions, set the value of each new name to that
1466 of the RHS (if we can derive a constant out of the RHS).
1467 Value-returning call statements also perform an assignment, and
1468 are handled here. */
1470 static enum ssa_prop_result
1471 visit_assignment (gimple stmt, tree *output_p)
1474 enum ssa_prop_result retval;
1476 tree lhs = gimple_get_lhs (stmt);
1478 gcc_assert (gimple_code (stmt) != GIMPLE_CALL
1479 || gimple_call_lhs (stmt) != NULL_TREE);
1481 if (gimple_assign_copy_p (stmt))
1483 tree rhs = gimple_assign_rhs1 (stmt);
1485 if (TREE_CODE (rhs) == SSA_NAME)
1487 /* For a simple copy operation, we copy the lattice values. */
1488 prop_value_t *nval = get_value (rhs);
1492 val = evaluate_stmt (stmt);
1495 /* Evaluate the statement, which could be
1496 either a GIMPLE_ASSIGN or a GIMPLE_CALL. */
1497 val = evaluate_stmt (stmt);
1499 retval = SSA_PROP_NOT_INTERESTING;
1501 /* Set the lattice value of the statement's output. */
1502 if (TREE_CODE (lhs) == SSA_NAME)
1504 /* If STMT is an assignment to an SSA_NAME, we only have one
1506 if (set_lattice_value (lhs, val))
1509 if (val.lattice_val == VARYING)
1510 retval = SSA_PROP_VARYING;
1512 retval = SSA_PROP_INTERESTING;
1520 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
1521 if it can determine which edge will be taken. Otherwise, return
1522 SSA_PROP_VARYING. */
1524 static enum ssa_prop_result
1525 visit_cond_stmt (gimple stmt, edge *taken_edge_p)
1530 block = gimple_bb (stmt);
1531 val = evaluate_stmt (stmt);
1533 /* Find which edge out of the conditional block will be taken and add it
1534 to the worklist. If no single edge can be determined statically,
1535 return SSA_PROP_VARYING to feed all the outgoing edges to the
1536 propagation engine. */
1537 *taken_edge_p = val.value ? find_taken_edge (block, val.value) : 0;
1539 return SSA_PROP_INTERESTING;
1541 return SSA_PROP_VARYING;
1545 /* Evaluate statement STMT. If the statement produces an output value and
1546 its evaluation changes the lattice value of its output, return
1547 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
1550 If STMT is a conditional branch and we can determine its truth
1551 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
1552 value, return SSA_PROP_VARYING. */
1554 static enum ssa_prop_result
1555 ccp_visit_stmt (gimple stmt, edge *taken_edge_p, tree *output_p)
1560 if (dump_file && (dump_flags & TDF_DETAILS))
1562 fprintf (dump_file, "\nVisiting statement:\n");
1563 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
1566 switch (gimple_code (stmt))
1569 /* If the statement is an assignment that produces a single
1570 output value, evaluate its RHS to see if the lattice value of
1571 its output has changed. */
1572 return visit_assignment (stmt, output_p);
1575 /* A value-returning call also performs an assignment. */
1576 if (gimple_call_lhs (stmt) != NULL_TREE)
1577 return visit_assignment (stmt, output_p);
1582 /* If STMT is a conditional branch, see if we can determine
1583 which branch will be taken. */
1584 /* FIXME. It appears that we should be able to optimize
1585 computed GOTOs here as well. */
1586 return visit_cond_stmt (stmt, taken_edge_p);
1592 /* Any other kind of statement is not interesting for constant
1593 propagation and, therefore, not worth simulating. */
1594 if (dump_file && (dump_flags & TDF_DETAILS))
1595 fprintf (dump_file, "No interesting values produced. Marked VARYING.\n");
1597 /* Definitions made by statements other than assignments to
1598 SSA_NAMEs represent unknown modifications to their outputs.
1599 Mark them VARYING. */
1600 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
1602 prop_value_t v = { VARYING, NULL_TREE };
1603 set_lattice_value (def, v);
1606 return SSA_PROP_VARYING;
1610 /* Main entry point for SSA Conditional Constant Propagation. */
1616 ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node);
1617 if (ccp_finalize ())
1618 return (TODO_cleanup_cfg | TODO_update_ssa | TODO_remove_unused_locals);
1627 return flag_tree_ccp != 0;
1631 struct gimple_opt_pass pass_ccp =
1636 gate_ccp, /* gate */
1637 do_ssa_ccp, /* execute */
1640 0, /* static_pass_number */
1641 TV_TREE_CCP, /* tv_id */
1642 PROP_cfg | PROP_ssa, /* properties_required */
1643 0, /* properties_provided */
1644 0, /* properties_destroyed */
1645 0, /* todo_flags_start */
1646 TODO_dump_func | TODO_verify_ssa
1647 | TODO_verify_stmts | TODO_ggc_collect/* todo_flags_finish */
1652 /* A subroutine of fold_stmt. Attempts to fold *(A+O) to A[X].
1653 BASE is an array type. OFFSET is a byte displacement. ORIG_TYPE
1654 is the desired result type.
1656 LOC is the location of the original expression. */
1659 maybe_fold_offset_to_array_ref (location_t loc, tree base, tree offset,
1661 bool allow_negative_idx)
1663 tree min_idx, idx, idx_type, elt_offset = integer_zero_node;
1664 tree array_type, elt_type, elt_size;
1667 /* If BASE is an ARRAY_REF, we can pick up another offset (this time
1668 measured in units of the size of elements type) from that ARRAY_REF).
1669 We can't do anything if either is variable.
1671 The case we handle here is *(&A[N]+O). */
1672 if (TREE_CODE (base) == ARRAY_REF)
1674 tree low_bound = array_ref_low_bound (base);
1676 elt_offset = TREE_OPERAND (base, 1);
1677 if (TREE_CODE (low_bound) != INTEGER_CST
1678 || TREE_CODE (elt_offset) != INTEGER_CST)
1681 elt_offset = int_const_binop (MINUS_EXPR, elt_offset, low_bound, 0);
1682 base = TREE_OPERAND (base, 0);
1685 /* Ignore stupid user tricks of indexing non-array variables. */
1686 array_type = TREE_TYPE (base);
1687 if (TREE_CODE (array_type) != ARRAY_TYPE)
1689 elt_type = TREE_TYPE (array_type);
1690 if (!useless_type_conversion_p (orig_type, elt_type))
1693 /* Use signed size type for intermediate computation on the index. */
1694 idx_type = signed_type_for (size_type_node);
1696 /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the
1697 element type (so we can use the alignment if it's not constant).
1698 Otherwise, compute the offset as an index by using a division. If the
1699 division isn't exact, then don't do anything. */
1700 elt_size = TYPE_SIZE_UNIT (elt_type);
1703 if (integer_zerop (offset))
1705 if (TREE_CODE (elt_size) != INTEGER_CST)
1706 elt_size = size_int (TYPE_ALIGN (elt_type));
1708 idx = build_int_cst (idx_type, 0);
1712 unsigned HOST_WIDE_INT lquo, lrem;
1713 HOST_WIDE_INT hquo, hrem;
1716 /* The final array offset should be signed, so we need
1717 to sign-extend the (possibly pointer) offset here
1718 and use signed division. */
1719 soffset = double_int_sext (tree_to_double_int (offset),
1720 TYPE_PRECISION (TREE_TYPE (offset)));
1721 if (TREE_CODE (elt_size) != INTEGER_CST
1722 || div_and_round_double (TRUNC_DIV_EXPR, 0,
1723 soffset.low, soffset.high,
1724 TREE_INT_CST_LOW (elt_size),
1725 TREE_INT_CST_HIGH (elt_size),
1726 &lquo, &hquo, &lrem, &hrem)
1730 idx = build_int_cst_wide (idx_type, lquo, hquo);
1733 /* Assume the low bound is zero. If there is a domain type, get the
1734 low bound, if any, convert the index into that type, and add the
1736 min_idx = build_int_cst (idx_type, 0);
1737 domain_type = TYPE_DOMAIN (array_type);
1740 idx_type = domain_type;
1741 if (TYPE_MIN_VALUE (idx_type))
1742 min_idx = TYPE_MIN_VALUE (idx_type);
1744 min_idx = fold_convert (idx_type, min_idx);
1746 if (TREE_CODE (min_idx) != INTEGER_CST)
1749 elt_offset = fold_convert (idx_type, elt_offset);
1752 if (!integer_zerop (min_idx))
1753 idx = int_const_binop (PLUS_EXPR, idx, min_idx, 0);
1754 if (!integer_zerop (elt_offset))
1755 idx = int_const_binop (PLUS_EXPR, idx, elt_offset, 0);
1757 /* Make sure to possibly truncate late after offsetting. */
1758 idx = fold_convert (idx_type, idx);
1760 /* We don't want to construct access past array bounds. For example
1763 should not be simplified into (*c)[14] or tree-vrp will
1764 give false warnings. The same is true for
1765 struct A { long x; char d[0]; } *a;
1767 which should be not folded to &a->d[-8]. */
1769 && TYPE_MAX_VALUE (domain_type)
1770 && TREE_CODE (TYPE_MAX_VALUE (domain_type)) == INTEGER_CST)
1772 tree up_bound = TYPE_MAX_VALUE (domain_type);
1774 if (tree_int_cst_lt (up_bound, idx)
1775 /* Accesses after the end of arrays of size 0 (gcc
1776 extension) and 1 are likely intentional ("struct
1778 && compare_tree_int (up_bound, 1) > 0)
1782 && TYPE_MIN_VALUE (domain_type))
1784 if (!allow_negative_idx
1785 && TREE_CODE (TYPE_MIN_VALUE (domain_type)) == INTEGER_CST
1786 && tree_int_cst_lt (idx, TYPE_MIN_VALUE (domain_type)))
1789 else if (!allow_negative_idx
1790 && compare_tree_int (idx, 0) < 0)
1794 tree t = build4 (ARRAY_REF, elt_type, base, idx, NULL_TREE, NULL_TREE);
1795 SET_EXPR_LOCATION (t, loc);
1801 /* Attempt to fold *(S+O) to S.X.
1802 BASE is a record type. OFFSET is a byte displacement. ORIG_TYPE
1803 is the desired result type.
1805 LOC is the location of the original expression. */
1808 maybe_fold_offset_to_component_ref (location_t loc, tree record_type,
1809 tree base, tree offset,
1810 tree orig_type, bool base_is_ptr)
1812 tree f, t, field_type, tail_array_field, field_offset;
1816 if (TREE_CODE (record_type) != RECORD_TYPE
1817 && TREE_CODE (record_type) != UNION_TYPE
1818 && TREE_CODE (record_type) != QUAL_UNION_TYPE)
1821 /* Short-circuit silly cases. */
1822 if (useless_type_conversion_p (record_type, orig_type))
1825 tail_array_field = NULL_TREE;
1826 for (f = TYPE_FIELDS (record_type); f ; f = TREE_CHAIN (f))
1830 if (TREE_CODE (f) != FIELD_DECL)
1832 if (DECL_BIT_FIELD (f))
1835 if (!DECL_FIELD_OFFSET (f))
1837 field_offset = byte_position (f);
1838 if (TREE_CODE (field_offset) != INTEGER_CST)
1841 /* ??? Java creates "interesting" fields for representing base classes.
1842 They have no name, and have no context. With no context, we get into
1843 trouble with nonoverlapping_component_refs_p. Skip them. */
1844 if (!DECL_FIELD_CONTEXT (f))
1847 /* The previous array field isn't at the end. */
1848 tail_array_field = NULL_TREE;
1850 /* Check to see if this offset overlaps with the field. */
1851 cmp = tree_int_cst_compare (field_offset, offset);
1855 field_type = TREE_TYPE (f);
1857 /* Here we exactly match the offset being checked. If the types match,
1858 then we can return that field. */
1860 && useless_type_conversion_p (orig_type, field_type))
1863 base = build1 (INDIRECT_REF, record_type, base);
1864 t = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE);
1868 /* Don't care about offsets into the middle of scalars. */
1869 if (!AGGREGATE_TYPE_P (field_type))
1872 /* Check for array at the end of the struct. This is often
1873 used as for flexible array members. We should be able to
1874 turn this into an array access anyway. */
1875 if (TREE_CODE (field_type) == ARRAY_TYPE)
1876 tail_array_field = f;
1878 /* Check the end of the field against the offset. */
1879 if (!DECL_SIZE_UNIT (f)
1880 || TREE_CODE (DECL_SIZE_UNIT (f)) != INTEGER_CST)
1882 t = int_const_binop (MINUS_EXPR, offset, field_offset, 1);
1883 if (!tree_int_cst_lt (t, DECL_SIZE_UNIT (f)))
1886 /* If we matched, then set offset to the displacement into
1889 new_base = build1 (INDIRECT_REF, record_type, base);
1892 protected_set_expr_location (new_base, loc);
1893 new_base = build3 (COMPONENT_REF, field_type, new_base, f, NULL_TREE);
1894 protected_set_expr_location (new_base, loc);
1896 /* Recurse to possibly find the match. */
1897 ret = maybe_fold_offset_to_array_ref (loc, new_base, t, orig_type,
1898 f == TYPE_FIELDS (record_type));
1901 ret = maybe_fold_offset_to_component_ref (loc, field_type, new_base, t,
1907 if (!tail_array_field)
1910 f = tail_array_field;
1911 field_type = TREE_TYPE (f);
1912 offset = int_const_binop (MINUS_EXPR, offset, byte_position (f), 1);
1914 /* If we get here, we've got an aggregate field, and a possibly
1915 nonzero offset into them. Recurse and hope for a valid match. */
1918 base = build1 (INDIRECT_REF, record_type, base);
1919 SET_EXPR_LOCATION (base, loc);
1921 base = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE);
1922 SET_EXPR_LOCATION (base, loc);
1924 t = maybe_fold_offset_to_array_ref (loc, base, offset, orig_type,
1925 f == TYPE_FIELDS (record_type));
1928 return maybe_fold_offset_to_component_ref (loc, field_type, base, offset,
1932 /* Attempt to express (ORIG_TYPE)BASE+OFFSET as BASE->field_of_orig_type
1933 or BASE[index] or by combination of those.
1935 LOC is the location of original expression.
1937 Before attempting the conversion strip off existing ADDR_EXPRs and
1938 handled component refs. */
1941 maybe_fold_offset_to_reference (location_t loc, tree base, tree offset,
1946 bool base_is_ptr = true;
1949 if (TREE_CODE (base) == ADDR_EXPR)
1951 base_is_ptr = false;
1953 base = TREE_OPERAND (base, 0);
1955 /* Handle case where existing COMPONENT_REF pick e.g. wrong field of union,
1956 so it needs to be removed and new COMPONENT_REF constructed.
1957 The wrong COMPONENT_REF are often constructed by folding the
1958 (type *)&object within the expression (type *)&object+offset */
1959 if (handled_component_p (base))
1961 HOST_WIDE_INT sub_offset, size, maxsize;
1963 newbase = get_ref_base_and_extent (base, &sub_offset,
1965 gcc_assert (newbase);
1968 && !(sub_offset & (BITS_PER_UNIT - 1)))
1972 offset = int_const_binop (PLUS_EXPR, offset,
1973 build_int_cst (TREE_TYPE (offset),
1974 sub_offset / BITS_PER_UNIT), 1);
1977 if (useless_type_conversion_p (orig_type, TREE_TYPE (base))
1978 && integer_zerop (offset))
1980 type = TREE_TYPE (base);
1985 if (!POINTER_TYPE_P (TREE_TYPE (base)))
1987 type = TREE_TYPE (TREE_TYPE (base));
1989 ret = maybe_fold_offset_to_component_ref (loc, type, base, offset,
1990 orig_type, base_is_ptr);
1995 base = build1 (INDIRECT_REF, type, base);
1996 SET_EXPR_LOCATION (base, loc);
1998 ret = maybe_fold_offset_to_array_ref (loc,
1999 base, offset, orig_type, true);
2004 /* Attempt to express (ORIG_TYPE)&BASE+OFFSET as &BASE->field_of_orig_type
2005 or &BASE[index] or by combination of those.
2007 LOC is the location of the original expression.
2009 Before attempting the conversion strip off existing component refs. */
2012 maybe_fold_offset_to_address (location_t loc, tree addr, tree offset,
2017 gcc_assert (POINTER_TYPE_P (TREE_TYPE (addr))
2018 && POINTER_TYPE_P (orig_type));
2020 t = maybe_fold_offset_to_reference (loc, addr, offset,
2021 TREE_TYPE (orig_type));
2027 /* For __builtin_object_size to function correctly we need to
2028 make sure not to fold address arithmetic so that we change
2029 reference from one array to another. This would happen for
2032 struct X { char s1[10]; char s2[10] } s;
2033 char *foo (void) { return &s.s2[-4]; }
2035 where we need to avoid generating &s.s1[6]. As the C and
2036 C++ frontends create different initial trees
2037 (char *) &s.s1 + -4 vs. &s.s1[-4] we have to do some
2038 sophisticated comparisons here. Note that checking for the
2039 condition after the fact is easier than trying to avoid doing
2042 if (TREE_CODE (orig) == ADDR_EXPR)
2043 orig = TREE_OPERAND (orig, 0);
2044 if ((TREE_CODE (orig) == ARRAY_REF
2045 || (TREE_CODE (orig) == COMPONENT_REF
2046 && TREE_CODE (TREE_TYPE (TREE_OPERAND (orig, 1))) == ARRAY_TYPE))
2047 && (TREE_CODE (t) == ARRAY_REF
2048 || TREE_CODE (t) == COMPONENT_REF)
2049 && !operand_equal_p (TREE_CODE (orig) == ARRAY_REF
2050 ? TREE_OPERAND (orig, 0) : orig,
2051 TREE_CODE (t) == ARRAY_REF
2052 ? TREE_OPERAND (t, 0) : t, 0))
2055 ptr_type = build_pointer_type (TREE_TYPE (t));
2056 if (!useless_type_conversion_p (orig_type, ptr_type))
2058 return build_fold_addr_expr_with_type_loc (loc, t, ptr_type);
2064 /* A subroutine of fold_stmt. Attempt to simplify *(BASE+OFFSET).
2065 Return the simplified expression, or NULL if nothing could be done. */
2068 maybe_fold_stmt_indirect (tree expr, tree base, tree offset)
2071 bool volatile_p = TREE_THIS_VOLATILE (expr);
2072 location_t loc = EXPR_LOCATION (expr);
2074 /* We may well have constructed a double-nested PLUS_EXPR via multiple
2075 substitutions. Fold that down to one. Remove NON_LVALUE_EXPRs that
2076 are sometimes added. */
2078 STRIP_TYPE_NOPS (base);
2079 TREE_OPERAND (expr, 0) = base;
2081 /* One possibility is that the address reduces to a string constant. */
2082 t = fold_read_from_constant_string (expr);
2086 /* Add in any offset from a POINTER_PLUS_EXPR. */
2087 if (TREE_CODE (base) == POINTER_PLUS_EXPR)
2091 offset2 = TREE_OPERAND (base, 1);
2092 if (TREE_CODE (offset2) != INTEGER_CST)
2094 base = TREE_OPERAND (base, 0);
2096 offset = fold_convert (sizetype,
2097 int_const_binop (PLUS_EXPR, offset, offset2, 1));
2100 if (TREE_CODE (base) == ADDR_EXPR)
2102 tree base_addr = base;
2104 /* Strip the ADDR_EXPR. */
2105 base = TREE_OPERAND (base, 0);
2107 /* Fold away CONST_DECL to its value, if the type is scalar. */
2108 if (TREE_CODE (base) == CONST_DECL
2109 && is_gimple_min_invariant (DECL_INITIAL (base)))
2110 return DECL_INITIAL (base);
2112 /* Try folding *(&B+O) to B.X. */
2113 t = maybe_fold_offset_to_reference (loc, base_addr, offset,
2117 /* Preserve volatileness of the original expression.
2118 We can end up with a plain decl here which is shared
2119 and we shouldn't mess with its flags. */
2121 TREE_THIS_VOLATILE (t) = volatile_p;
2127 /* We can get here for out-of-range string constant accesses,
2128 such as "_"[3]. Bail out of the entire substitution search
2129 and arrange for the entire statement to be replaced by a
2130 call to __builtin_trap. In all likelihood this will all be
2131 constant-folded away, but in the meantime we can't leave with
2132 something that get_expr_operands can't understand. */
2136 if (TREE_CODE (t) == ADDR_EXPR
2137 && TREE_CODE (TREE_OPERAND (t, 0)) == STRING_CST)
2139 /* FIXME: Except that this causes problems elsewhere with dead
2140 code not being deleted, and we die in the rtl expanders
2141 because we failed to remove some ssa_name. In the meantime,
2142 just return zero. */
2143 /* FIXME2: This condition should be signaled by
2144 fold_read_from_constant_string directly, rather than
2145 re-checking for it here. */
2146 return integer_zero_node;
2149 /* Try folding *(B+O) to B->X. Still an improvement. */
2150 if (POINTER_TYPE_P (TREE_TYPE (base)))
2152 t = maybe_fold_offset_to_reference (loc, base, offset,
2159 /* Otherwise we had an offset that we could not simplify. */
2164 /* A quaint feature extant in our address arithmetic is that there
2165 can be hidden type changes here. The type of the result need
2166 not be the same as the type of the input pointer.
2168 What we're after here is an expression of the form
2169 (T *)(&array + const)
2170 where array is OP0, const is OP1, RES_TYPE is T and
2171 the cast doesn't actually exist, but is implicit in the
2172 type of the POINTER_PLUS_EXPR. We'd like to turn this into
2174 which may be able to propagate further. */
2177 maybe_fold_stmt_addition (location_t loc, tree res_type, tree op0, tree op1)
2182 /* The first operand should be an ADDR_EXPR. */
2183 if (TREE_CODE (op0) != ADDR_EXPR)
2185 op0 = TREE_OPERAND (op0, 0);
2187 /* It had better be a constant. */
2188 if (TREE_CODE (op1) != INTEGER_CST)
2190 /* Or op0 should now be A[0] and the non-constant offset defined
2191 via a multiplication by the array element size. */
2192 if (TREE_CODE (op0) == ARRAY_REF
2193 && integer_zerop (TREE_OPERAND (op0, 1))
2194 && TREE_CODE (op1) == SSA_NAME
2195 && host_integerp (TYPE_SIZE_UNIT (TREE_TYPE (op0)), 1))
2197 gimple offset_def = SSA_NAME_DEF_STMT (op1);
2198 if (!is_gimple_assign (offset_def))
2201 if (gimple_assign_rhs_code (offset_def) == MULT_EXPR
2202 && TREE_CODE (gimple_assign_rhs2 (offset_def)) == INTEGER_CST
2203 && tree_int_cst_equal (gimple_assign_rhs2 (offset_def),
2204 TYPE_SIZE_UNIT (TREE_TYPE (op0))))
2205 return build1 (ADDR_EXPR, res_type,
2206 build4 (ARRAY_REF, TREE_TYPE (op0),
2207 TREE_OPERAND (op0, 0),
2208 gimple_assign_rhs1 (offset_def),
2209 TREE_OPERAND (op0, 2),
2210 TREE_OPERAND (op0, 3)));
2211 else if (integer_onep (TYPE_SIZE_UNIT (TREE_TYPE (op0)))
2212 && gimple_assign_rhs_code (offset_def) != MULT_EXPR)
2213 return build1 (ADDR_EXPR, res_type,
2214 build4 (ARRAY_REF, TREE_TYPE (op0),
2215 TREE_OPERAND (op0, 0),
2217 TREE_OPERAND (op0, 2),
2218 TREE_OPERAND (op0, 3)));
2223 /* If the first operand is an ARRAY_REF, expand it so that we can fold
2224 the offset into it. */
2225 while (TREE_CODE (op0) == ARRAY_REF)
2227 tree array_obj = TREE_OPERAND (op0, 0);
2228 tree array_idx = TREE_OPERAND (op0, 1);
2229 tree elt_type = TREE_TYPE (op0);
2230 tree elt_size = TYPE_SIZE_UNIT (elt_type);
2233 if (TREE_CODE (array_idx) != INTEGER_CST)
2235 if (TREE_CODE (elt_size) != INTEGER_CST)
2238 /* Un-bias the index by the min index of the array type. */
2239 min_idx = TYPE_DOMAIN (TREE_TYPE (array_obj));
2242 min_idx = TYPE_MIN_VALUE (min_idx);
2245 if (TREE_CODE (min_idx) != INTEGER_CST)
2248 array_idx = fold_convert (TREE_TYPE (min_idx), array_idx);
2249 if (!integer_zerop (min_idx))
2250 array_idx = int_const_binop (MINUS_EXPR, array_idx,
2255 /* Convert the index to a byte offset. */
2256 array_idx = fold_convert (sizetype, array_idx);
2257 array_idx = int_const_binop (MULT_EXPR, array_idx, elt_size, 0);
2259 /* Update the operands for the next round, or for folding. */
2260 op1 = int_const_binop (PLUS_EXPR,
2265 ptd_type = TREE_TYPE (res_type);
2266 /* If we want a pointer to void, reconstruct the reference from the
2267 array element type. A pointer to that can be trivially converted
2268 to void *. This happens as we fold (void *)(ptr p+ off). */
2269 if (VOID_TYPE_P (ptd_type)
2270 && TREE_CODE (TREE_TYPE (op0)) == ARRAY_TYPE)
2271 ptd_type = TREE_TYPE (TREE_TYPE (op0));
2273 /* At which point we can try some of the same things as for indirects. */
2274 t = maybe_fold_offset_to_array_ref (loc, op0, op1, ptd_type, true);
2276 t = maybe_fold_offset_to_component_ref (loc, TREE_TYPE (op0), op0, op1,
2280 t = build1 (ADDR_EXPR, res_type, t);
2281 SET_EXPR_LOCATION (t, loc);
2287 /* Subroutine of fold_stmt. We perform several simplifications of the
2288 memory reference tree EXPR and make sure to re-gimplify them properly
2289 after propagation of constant addresses. IS_LHS is true if the
2290 reference is supposed to be an lvalue. */
2293 maybe_fold_reference (tree expr, bool is_lhs)
2297 if (TREE_CODE (expr) == ARRAY_REF
2300 tree tem = fold_read_from_constant_string (expr);
2305 /* ??? We might want to open-code the relevant remaining cases
2306 to avoid using the generic fold. */
2307 if (handled_component_p (*t)
2308 && CONSTANT_CLASS_P (TREE_OPERAND (*t, 0)))
2310 tree tem = fold (*t);
2315 while (handled_component_p (*t))
2316 t = &TREE_OPERAND (*t, 0);
2318 if (TREE_CODE (*t) == INDIRECT_REF)
2320 tree tem = maybe_fold_stmt_indirect (*t, TREE_OPERAND (*t, 0),
2322 /* Avoid folding *"abc" = 5 into 'a' = 5. */
2323 if (is_lhs && tem && CONSTANT_CLASS_P (tem))
2326 && TREE_CODE (TREE_OPERAND (*t, 0)) == ADDR_EXPR)
2327 /* If we had a good reason for propagating the address here,
2328 make sure we end up with valid gimple. See PR34989. */
2329 tem = TREE_OPERAND (TREE_OPERAND (*t, 0), 0);
2334 tem = maybe_fold_reference (expr, is_lhs);
2345 /* Return the string length, maximum string length or maximum value of
2347 If ARG is an SSA name variable, follow its use-def chains. If LENGTH
2348 is not NULL and, for TYPE == 0, its value is not equal to the length
2349 we determine or if we are unable to determine the length or value,
2350 return false. VISITED is a bitmap of visited variables.
2351 TYPE is 0 if string length should be returned, 1 for maximum string
2352 length and 2 for maximum value ARG can have. */
2355 get_maxval_strlen (tree arg, tree *length, bitmap visited, int type)
2360 if (TREE_CODE (arg) != SSA_NAME)
2362 if (TREE_CODE (arg) == COND_EXPR)
2363 return get_maxval_strlen (COND_EXPR_THEN (arg), length, visited, type)
2364 && get_maxval_strlen (COND_EXPR_ELSE (arg), length, visited, type);
2365 /* We can end up with &(*iftmp_1)[0] here as well, so handle it. */
2366 else if (TREE_CODE (arg) == ADDR_EXPR
2367 && TREE_CODE (TREE_OPERAND (arg, 0)) == ARRAY_REF
2368 && integer_zerop (TREE_OPERAND (TREE_OPERAND (arg, 0), 1)))
2370 tree aop0 = TREE_OPERAND (TREE_OPERAND (arg, 0), 0);
2371 if (TREE_CODE (aop0) == INDIRECT_REF
2372 && TREE_CODE (TREE_OPERAND (aop0, 0)) == SSA_NAME)
2373 return get_maxval_strlen (TREE_OPERAND (aop0, 0),
2374 length, visited, type);
2380 if (TREE_CODE (val) != INTEGER_CST
2381 || tree_int_cst_sgn (val) < 0)
2385 val = c_strlen (arg, 1);
2393 if (TREE_CODE (*length) != INTEGER_CST
2394 || TREE_CODE (val) != INTEGER_CST)
2397 if (tree_int_cst_lt (*length, val))
2401 else if (simple_cst_equal (val, *length) != 1)
2409 /* If we were already here, break the infinite cycle. */
2410 if (bitmap_bit_p (visited, SSA_NAME_VERSION (arg)))
2412 bitmap_set_bit (visited, SSA_NAME_VERSION (arg));
2415 def_stmt = SSA_NAME_DEF_STMT (var);
2417 switch (gimple_code (def_stmt))
2420 /* The RHS of the statement defining VAR must either have a
2421 constant length or come from another SSA_NAME with a constant
2423 if (gimple_assign_single_p (def_stmt)
2424 || gimple_assign_unary_nop_p (def_stmt))
2426 tree rhs = gimple_assign_rhs1 (def_stmt);
2427 return get_maxval_strlen (rhs, length, visited, type);
2433 /* All the arguments of the PHI node must have the same constant
2437 for (i = 0; i < gimple_phi_num_args (def_stmt); i++)
2439 tree arg = gimple_phi_arg (def_stmt, i)->def;
2441 /* If this PHI has itself as an argument, we cannot
2442 determine the string length of this argument. However,
2443 if we can find a constant string length for the other
2444 PHI args then we can still be sure that this is a
2445 constant string length. So be optimistic and just
2446 continue with the next argument. */
2447 if (arg == gimple_phi_result (def_stmt))
2450 if (!get_maxval_strlen (arg, length, visited, type))
2462 /* Fold builtin call in statement STMT. Returns a simplified tree.
2463 We may return a non-constant expression, including another call
2464 to a different function and with different arguments, e.g.,
2465 substituting memcpy for strcpy when the string length is known.
2466 Note that some builtins expand into inline code that may not
2467 be valid in GIMPLE. Callers must take care. */
2470 ccp_fold_builtin (gimple stmt)
2472 tree result, val[3];
2478 location_t loc = gimple_location (stmt);
2480 gcc_assert (is_gimple_call (stmt));
2482 ignore = (gimple_call_lhs (stmt) == NULL);
2484 /* First try the generic builtin folder. If that succeeds, return the
2486 result = fold_call_stmt (stmt, ignore);
2490 STRIP_NOPS (result);
2494 /* Ignore MD builtins. */
2495 callee = gimple_call_fndecl (stmt);
2496 if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_MD)
2499 /* If the builtin could not be folded, and it has no argument list,
2501 nargs = gimple_call_num_args (stmt);
2505 /* Limit the work only for builtins we know how to simplify. */
2506 switch (DECL_FUNCTION_CODE (callee))
2508 case BUILT_IN_STRLEN:
2509 case BUILT_IN_FPUTS:
2510 case BUILT_IN_FPUTS_UNLOCKED:
2514 case BUILT_IN_STRCPY:
2515 case BUILT_IN_STRNCPY:
2519 case BUILT_IN_MEMCPY_CHK:
2520 case BUILT_IN_MEMPCPY_CHK:
2521 case BUILT_IN_MEMMOVE_CHK:
2522 case BUILT_IN_MEMSET_CHK:
2523 case BUILT_IN_STRNCPY_CHK:
2527 case BUILT_IN_STRCPY_CHK:
2528 case BUILT_IN_STPCPY_CHK:
2532 case BUILT_IN_SNPRINTF_CHK:
2533 case BUILT_IN_VSNPRINTF_CHK:
2541 if (arg_idx >= nargs)
2544 /* Try to use the dataflow information gathered by the CCP process. */
2545 visited = BITMAP_ALLOC (NULL);
2546 bitmap_clear (visited);
2548 memset (val, 0, sizeof (val));
2549 a = gimple_call_arg (stmt, arg_idx);
2550 if (!get_maxval_strlen (a, &val[arg_idx], visited, type))
2551 val[arg_idx] = NULL_TREE;
2553 BITMAP_FREE (visited);
2556 switch (DECL_FUNCTION_CODE (callee))
2558 case BUILT_IN_STRLEN:
2559 if (val[0] && nargs == 1)
2562 fold_convert (TREE_TYPE (gimple_call_lhs (stmt)), val[0]);
2564 /* If the result is not a valid gimple value, or not a cast
2565 of a valid gimple value, then we can not use the result. */
2566 if (is_gimple_val (new_val)
2567 || (is_gimple_cast (new_val)
2568 && is_gimple_val (TREE_OPERAND (new_val, 0))))
2573 case BUILT_IN_STRCPY:
2574 if (val[1] && is_gimple_val (val[1]) && nargs == 2)
2575 result = fold_builtin_strcpy (loc, callee,
2576 gimple_call_arg (stmt, 0),
2577 gimple_call_arg (stmt, 1),
2581 case BUILT_IN_STRNCPY:
2582 if (val[1] && is_gimple_val (val[1]) && nargs == 3)
2583 result = fold_builtin_strncpy (loc, callee,
2584 gimple_call_arg (stmt, 0),
2585 gimple_call_arg (stmt, 1),
2586 gimple_call_arg (stmt, 2),
2590 case BUILT_IN_FPUTS:
2592 result = fold_builtin_fputs (loc, gimple_call_arg (stmt, 0),
2593 gimple_call_arg (stmt, 1),
2594 ignore, false, val[0]);
2597 case BUILT_IN_FPUTS_UNLOCKED:
2599 result = fold_builtin_fputs (loc, gimple_call_arg (stmt, 0),
2600 gimple_call_arg (stmt, 1),
2601 ignore, true, val[0]);
2604 case BUILT_IN_MEMCPY_CHK:
2605 case BUILT_IN_MEMPCPY_CHK:
2606 case BUILT_IN_MEMMOVE_CHK:
2607 case BUILT_IN_MEMSET_CHK:
2608 if (val[2] && is_gimple_val (val[2]) && nargs == 4)
2609 result = fold_builtin_memory_chk (loc, callee,
2610 gimple_call_arg (stmt, 0),
2611 gimple_call_arg (stmt, 1),
2612 gimple_call_arg (stmt, 2),
2613 gimple_call_arg (stmt, 3),
2615 DECL_FUNCTION_CODE (callee));
2618 case BUILT_IN_STRCPY_CHK:
2619 case BUILT_IN_STPCPY_CHK:
2620 if (val[1] && is_gimple_val (val[1]) && nargs == 3)
2621 result = fold_builtin_stxcpy_chk (loc, callee,
2622 gimple_call_arg (stmt, 0),
2623 gimple_call_arg (stmt, 1),
2624 gimple_call_arg (stmt, 2),
2626 DECL_FUNCTION_CODE (callee));
2629 case BUILT_IN_STRNCPY_CHK:
2630 if (val[2] && is_gimple_val (val[2]) && nargs == 4)
2631 result = fold_builtin_strncpy_chk (loc, gimple_call_arg (stmt, 0),
2632 gimple_call_arg (stmt, 1),
2633 gimple_call_arg (stmt, 2),
2634 gimple_call_arg (stmt, 3),
2638 case BUILT_IN_SNPRINTF_CHK:
2639 case BUILT_IN_VSNPRINTF_CHK:
2640 if (val[1] && is_gimple_val (val[1]))
2641 result = gimple_fold_builtin_snprintf_chk (stmt, val[1],
2642 DECL_FUNCTION_CODE (callee));
2649 if (result && ignore)
2650 result = fold_ignored_result (result);
2654 /* Attempt to fold an assignment statement pointed-to by SI. Returns a
2655 replacement rhs for the statement or NULL_TREE if no simplification
2656 could be made. It is assumed that the operands have been previously
2660 fold_gimple_assign (gimple_stmt_iterator *si)
2662 gimple stmt = gsi_stmt (*si);
2663 enum tree_code subcode = gimple_assign_rhs_code (stmt);
2664 location_t loc = gimple_location (stmt);
2666 tree result = NULL_TREE;
2668 switch (get_gimple_rhs_class (subcode))
2670 case GIMPLE_SINGLE_RHS:
2672 tree rhs = gimple_assign_rhs1 (stmt);
2674 /* Try to fold a conditional expression. */
2675 if (TREE_CODE (rhs) == COND_EXPR)
2677 tree op0 = COND_EXPR_COND (rhs);
2680 location_t cond_loc = EXPR_LOCATION (rhs);
2682 if (COMPARISON_CLASS_P (op0))
2684 fold_defer_overflow_warnings ();
2685 tem = fold_binary_loc (cond_loc,
2686 TREE_CODE (op0), TREE_TYPE (op0),
2687 TREE_OPERAND (op0, 0),
2688 TREE_OPERAND (op0, 1));
2689 /* This is actually a conditional expression, not a GIMPLE
2690 conditional statement, however, the valid_gimple_rhs_p
2691 test still applies. */
2692 set = (tem && is_gimple_condexpr (tem)
2693 && valid_gimple_rhs_p (tem));
2694 fold_undefer_overflow_warnings (set, stmt, 0);
2696 else if (is_gimple_min_invariant (op0))
2705 result = fold_build3_loc (cond_loc, COND_EXPR, TREE_TYPE (rhs), tem,
2706 COND_EXPR_THEN (rhs), COND_EXPR_ELSE (rhs));
2709 else if (TREE_CODE (rhs) == TARGET_MEM_REF)
2710 return maybe_fold_tmr (rhs);
2712 else if (REFERENCE_CLASS_P (rhs))
2713 return maybe_fold_reference (rhs, false);
2715 else if (TREE_CODE (rhs) == ADDR_EXPR)
2717 tree tem = maybe_fold_reference (TREE_OPERAND (rhs, 0), true);
2719 result = fold_convert (TREE_TYPE (rhs),
2720 build_fold_addr_expr_loc (loc, tem));
2723 else if (TREE_CODE (rhs) == CONSTRUCTOR
2724 && TREE_CODE (TREE_TYPE (rhs)) == VECTOR_TYPE
2725 && (CONSTRUCTOR_NELTS (rhs)
2726 == TYPE_VECTOR_SUBPARTS (TREE_TYPE (rhs))))
2728 /* Fold a constant vector CONSTRUCTOR to VECTOR_CST. */
2732 FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (rhs), i, val)
2733 if (TREE_CODE (val) != INTEGER_CST
2734 && TREE_CODE (val) != REAL_CST
2735 && TREE_CODE (val) != FIXED_CST)
2738 return build_vector_from_ctor (TREE_TYPE (rhs),
2739 CONSTRUCTOR_ELTS (rhs));
2742 /* If we couldn't fold the RHS, hand over to the generic
2744 if (result == NULL_TREE)
2745 result = fold (rhs);
2747 /* Strip away useless type conversions. Both the NON_LVALUE_EXPR
2748 that may have been added by fold, and "useless" type
2749 conversions that might now be apparent due to propagation. */
2750 STRIP_USELESS_TYPE_CONVERSION (result);
2752 if (result != rhs && valid_gimple_rhs_p (result))
2759 case GIMPLE_UNARY_RHS:
2761 tree rhs = gimple_assign_rhs1 (stmt);
2763 result = fold_unary_loc (loc, subcode, gimple_expr_type (stmt), rhs);
2766 /* If the operation was a conversion do _not_ mark a
2767 resulting constant with TREE_OVERFLOW if the original
2768 constant was not. These conversions have implementation
2769 defined behavior and retaining the TREE_OVERFLOW flag
2770 here would confuse later passes such as VRP. */
2771 if (CONVERT_EXPR_CODE_P (subcode)
2772 && TREE_CODE (result) == INTEGER_CST
2773 && TREE_CODE (rhs) == INTEGER_CST)
2774 TREE_OVERFLOW (result) = TREE_OVERFLOW (rhs);
2776 STRIP_USELESS_TYPE_CONVERSION (result);
2777 if (valid_gimple_rhs_p (result))
2780 else if (CONVERT_EXPR_CODE_P (subcode)
2781 && POINTER_TYPE_P (gimple_expr_type (stmt))
2782 && POINTER_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (stmt))))
2784 tree type = gimple_expr_type (stmt);
2785 tree t = maybe_fold_offset_to_address (loc,
2786 gimple_assign_rhs1 (stmt),
2787 integer_zero_node, type);
2794 case GIMPLE_BINARY_RHS:
2795 /* Try to fold pointer addition. */
2796 if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR)
2798 tree type = TREE_TYPE (gimple_assign_rhs1 (stmt));
2799 if (TREE_CODE (TREE_TYPE (type)) == ARRAY_TYPE)
2801 type = build_pointer_type (TREE_TYPE (TREE_TYPE (type)));
2802 if (!useless_type_conversion_p
2803 (TREE_TYPE (gimple_assign_lhs (stmt)), type))
2804 type = TREE_TYPE (gimple_assign_rhs1 (stmt));
2806 result = maybe_fold_stmt_addition (gimple_location (stmt),
2808 gimple_assign_rhs1 (stmt),
2809 gimple_assign_rhs2 (stmt));
2813 result = fold_binary_loc (loc, subcode,
2814 TREE_TYPE (gimple_assign_lhs (stmt)),
2815 gimple_assign_rhs1 (stmt),
2816 gimple_assign_rhs2 (stmt));
2820 STRIP_USELESS_TYPE_CONVERSION (result);
2821 if (valid_gimple_rhs_p (result))
2824 /* Fold might have produced non-GIMPLE, so if we trust it blindly
2825 we lose canonicalization opportunities. Do not go again
2826 through fold here though, or the same non-GIMPLE will be
2828 if (commutative_tree_code (subcode)
2829 && tree_swap_operands_p (gimple_assign_rhs1 (stmt),
2830 gimple_assign_rhs2 (stmt), false))
2831 return build2 (subcode, TREE_TYPE (gimple_assign_lhs (stmt)),
2832 gimple_assign_rhs2 (stmt),
2833 gimple_assign_rhs1 (stmt));
2837 case GIMPLE_INVALID_RHS:
2844 /* Attempt to fold a conditional statement. Return true if any changes were
2845 made. We only attempt to fold the condition expression, and do not perform
2846 any transformation that would require alteration of the cfg. It is
2847 assumed that the operands have been previously folded. */
2850 fold_gimple_cond (gimple stmt)
2852 tree result = fold_binary_loc (gimple_location (stmt),
2853 gimple_cond_code (stmt),
2855 gimple_cond_lhs (stmt),
2856 gimple_cond_rhs (stmt));
2860 STRIP_USELESS_TYPE_CONVERSION (result);
2861 if (is_gimple_condexpr (result) && valid_gimple_rhs_p (result))
2863 gimple_cond_set_condition_from_tree (stmt, result);
2872 /* Attempt to fold a call statement referenced by the statement iterator GSI.
2873 The statement may be replaced by another statement, e.g., if the call
2874 simplifies to a constant value. Return true if any changes were made.
2875 It is assumed that the operands have been previously folded. */
2878 fold_gimple_call (gimple_stmt_iterator *gsi)
2880 gimple stmt = gsi_stmt (*gsi);
2882 tree callee = gimple_call_fndecl (stmt);
2884 /* Check for builtins that CCP can handle using information not
2885 available in the generic fold routines. */
2886 if (callee && DECL_BUILT_IN (callee))
2888 tree result = ccp_fold_builtin (stmt);
2891 return update_call_from_tree (gsi, result);
2895 /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve
2896 here are when we've propagated the address of a decl into the
2898 /* ??? Should perhaps do this in fold proper. However, doing it
2899 there requires that we create a new CALL_EXPR, and that requires
2900 copying EH region info to the new node. Easier to just do it
2901 here where we can just smash the call operand. */
2902 /* ??? Is there a good reason not to do this in fold_stmt_inplace? */
2903 callee = gimple_call_fn (stmt);
2904 if (TREE_CODE (callee) == OBJ_TYPE_REF
2905 && lang_hooks.fold_obj_type_ref
2906 && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee)) == ADDR_EXPR
2907 && DECL_P (TREE_OPERAND
2908 (OBJ_TYPE_REF_OBJECT (callee), 0)))
2912 /* ??? Caution: Broken ADDR_EXPR semantics means that
2913 looking at the type of the operand of the addr_expr
2914 can yield an array type. See silly exception in
2915 check_pointer_types_r. */
2916 t = TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee)));
2917 t = lang_hooks.fold_obj_type_ref (callee, t);
2920 gimple_call_set_fn (stmt, t);
2929 /* Worker for both fold_stmt and fold_stmt_inplace. The INPLACE argument
2930 distinguishes both cases. */
2933 fold_stmt_1 (gimple_stmt_iterator *gsi, bool inplace)
2935 bool changed = false;
2936 gimple stmt = gsi_stmt (*gsi);
2939 /* Fold the main computation performed by the statement. */
2940 switch (gimple_code (stmt))
2944 unsigned old_num_ops = gimple_num_ops (stmt);
2945 tree new_rhs = fold_gimple_assign (gsi);
2946 if (new_rhs != NULL_TREE
2948 || get_gimple_rhs_num_ops (TREE_CODE (new_rhs)) < old_num_ops))
2950 gimple_assign_set_rhs_from_tree (gsi, new_rhs);
2957 changed |= fold_gimple_cond (stmt);
2961 /* Fold *& in call arguments. */
2962 for (i = 0; i < gimple_call_num_args (stmt); ++i)
2963 if (REFERENCE_CLASS_P (gimple_call_arg (stmt, i)))
2965 tree tmp = maybe_fold_reference (gimple_call_arg (stmt, i), false);
2968 gimple_call_set_arg (stmt, i, tmp);
2972 /* The entire statement may be replaced in this case. */
2974 changed |= fold_gimple_call (gsi);
2978 /* Fold *& in asm operands. */
2979 for (i = 0; i < gimple_asm_noutputs (stmt); ++i)
2981 tree link = gimple_asm_output_op (stmt, i);
2982 tree op = TREE_VALUE (link);
2983 if (REFERENCE_CLASS_P (op)
2984 && (op = maybe_fold_reference (op, true)) != NULL_TREE)
2986 TREE_VALUE (link) = op;
2990 for (i = 0; i < gimple_asm_ninputs (stmt); ++i)
2992 tree link = gimple_asm_input_op (stmt, i);
2993 tree op = TREE_VALUE (link);
2994 if (REFERENCE_CLASS_P (op)
2995 && (op = maybe_fold_reference (op, false)) != NULL_TREE)
2997 TREE_VALUE (link) = op;
3006 stmt = gsi_stmt (*gsi);
3008 /* Fold *& on the lhs. */
3009 if (gimple_has_lhs (stmt))
3011 tree lhs = gimple_get_lhs (stmt);
3012 if (lhs && REFERENCE_CLASS_P (lhs))
3014 tree new_lhs = maybe_fold_reference (lhs, true);
3017 gimple_set_lhs (stmt, new_lhs);
3026 /* Fold the statement pointed to by GSI. In some cases, this function may
3027 replace the whole statement with a new one. Returns true iff folding
3029 The statement pointed to by GSI should be in valid gimple form but may
3030 be in unfolded state as resulting from for example constant propagation
3031 which can produce *&x = 0. */
3034 fold_stmt (gimple_stmt_iterator *gsi)
3036 return fold_stmt_1 (gsi, false);
3039 /* Perform the minimal folding on statement STMT. Only operations like
3040 *&x created by constant propagation are handled. The statement cannot
3041 be replaced with a new one. Return true if the statement was
3042 changed, false otherwise.
3043 The statement STMT should be in valid gimple form but may
3044 be in unfolded state as resulting from for example constant propagation
3045 which can produce *&x = 0. */
3048 fold_stmt_inplace (gimple stmt)
3050 gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
3051 bool changed = fold_stmt_1 (&gsi, true);
3052 gcc_assert (gsi_stmt (gsi) == stmt);
3056 /* Try to optimize out __builtin_stack_restore. Optimize it out
3057 if there is another __builtin_stack_restore in the same basic
3058 block and no calls or ASM_EXPRs are in between, or if this block's
3059 only outgoing edge is to EXIT_BLOCK and there are no calls or
3060 ASM_EXPRs after this __builtin_stack_restore. */
3063 optimize_stack_restore (gimple_stmt_iterator i)
3066 gimple stmt, stack_save;
3067 gimple_stmt_iterator stack_save_gsi;
3069 basic_block bb = gsi_bb (i);
3070 gimple call = gsi_stmt (i);
3072 if (gimple_code (call) != GIMPLE_CALL
3073 || gimple_call_num_args (call) != 1
3074 || TREE_CODE (gimple_call_arg (call, 0)) != SSA_NAME
3075 || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call, 0))))
3078 for (gsi_next (&i); !gsi_end_p (i); gsi_next (&i))
3080 stmt = gsi_stmt (i);
3081 if (gimple_code (stmt) == GIMPLE_ASM)
3083 if (gimple_code (stmt) != GIMPLE_CALL)
3086 callee = gimple_call_fndecl (stmt);
3087 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
3090 if (DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_RESTORE)
3095 && (! single_succ_p (bb)
3096 || single_succ_edge (bb)->dest != EXIT_BLOCK_PTR))
3099 stack_save = SSA_NAME_DEF_STMT (gimple_call_arg (call, 0));
3100 if (gimple_code (stack_save) != GIMPLE_CALL
3101 || gimple_call_lhs (stack_save) != gimple_call_arg (call, 0)
3102 || stmt_could_throw_p (stack_save)
3103 || !has_single_use (gimple_call_arg (call, 0)))
3106 callee = gimple_call_fndecl (stack_save);
3108 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
3109 || DECL_FUNCTION_CODE (callee) != BUILT_IN_STACK_SAVE
3110 || gimple_call_num_args (stack_save) != 0)
3113 stack_save_gsi = gsi_for_stmt (stack_save);
3114 rhs = build_int_cst (TREE_TYPE (gimple_call_arg (call, 0)), 0);
3115 if (!update_call_from_tree (&stack_save_gsi, rhs))
3118 /* No effect, so the statement will be deleted. */
3119 return integer_zero_node;
3122 /* If va_list type is a simple pointer and nothing special is needed,
3123 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
3124 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
3125 pointer assignment. */
3128 optimize_stdarg_builtin (gimple call)
3130 tree callee, lhs, rhs, cfun_va_list;
3131 bool va_list_simple_ptr;
3132 location_t loc = gimple_location (call);
3134 if (gimple_code (call) != GIMPLE_CALL)
3137 callee = gimple_call_fndecl (call);
3139 cfun_va_list = targetm.fn_abi_va_list (callee);
3140 va_list_simple_ptr = POINTER_TYPE_P (cfun_va_list)
3141 && (TREE_TYPE (cfun_va_list) == void_type_node
3142 || TREE_TYPE (cfun_va_list) == char_type_node);
3144 switch (DECL_FUNCTION_CODE (callee))
3146 case BUILT_IN_VA_START:
3147 if (!va_list_simple_ptr
3148 || targetm.expand_builtin_va_start != NULL
3149 || built_in_decls[BUILT_IN_NEXT_ARG] == NULL)
3152 if (gimple_call_num_args (call) != 2)
3155 lhs = gimple_call_arg (call, 0);
3156 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
3157 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
3158 != TYPE_MAIN_VARIANT (cfun_va_list))
3161 lhs = build_fold_indirect_ref_loc (loc, lhs);
3162 rhs = build_call_expr_loc (loc, built_in_decls[BUILT_IN_NEXT_ARG],
3163 1, integer_zero_node);
3164 rhs = fold_convert_loc (loc, TREE_TYPE (lhs), rhs);
3165 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
3167 case BUILT_IN_VA_COPY:
3168 if (!va_list_simple_ptr)
3171 if (gimple_call_num_args (call) != 2)
3174 lhs = gimple_call_arg (call, 0);
3175 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
3176 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
3177 != TYPE_MAIN_VARIANT (cfun_va_list))
3180 lhs = build_fold_indirect_ref_loc (loc, lhs);
3181 rhs = gimple_call_arg (call, 1);
3182 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs))
3183 != TYPE_MAIN_VARIANT (cfun_va_list))
3186 rhs = fold_convert_loc (loc, TREE_TYPE (lhs), rhs);
3187 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
3189 case BUILT_IN_VA_END:
3190 /* No effect, so the statement will be deleted. */
3191 return integer_zero_node;
3198 /* Convert EXPR into a GIMPLE value suitable for substitution on the
3199 RHS of an assignment. Insert the necessary statements before
3200 iterator *SI_P. The statement at *SI_P, which must be a GIMPLE_CALL
3201 is replaced. If the call is expected to produces a result, then it
3202 is replaced by an assignment of the new RHS to the result variable.
3203 If the result is to be ignored, then the call is replaced by a
3207 gimplify_and_update_call_from_tree (gimple_stmt_iterator *si_p, tree expr)
3210 tree tmp = NULL_TREE; /* Silence warning. */
3211 gimple stmt, new_stmt;
3212 gimple_stmt_iterator i;
3213 gimple_seq stmts = gimple_seq_alloc();
3214 struct gimplify_ctx gctx;
3216 stmt = gsi_stmt (*si_p);
3218 gcc_assert (is_gimple_call (stmt));
3220 lhs = gimple_call_lhs (stmt);
3222 push_gimplify_context (&gctx);
3224 if (lhs == NULL_TREE)
3225 gimplify_and_add (expr, &stmts);
3227 tmp = get_initialized_tmp_var (expr, &stmts, NULL);
3229 pop_gimplify_context (NULL);
3231 if (gimple_has_location (stmt))
3232 annotate_all_with_location (stmts, gimple_location (stmt));
3234 /* The replacement can expose previously unreferenced variables. */
3235 for (i = gsi_start (stmts); !gsi_end_p (i); gsi_next (&i))
3237 new_stmt = gsi_stmt (i);
3238 find_new_referenced_vars (new_stmt);
3239 gsi_insert_before (si_p, new_stmt, GSI_NEW_STMT);
3240 mark_symbols_for_renaming (new_stmt);
3244 if (lhs == NULL_TREE)
3246 new_stmt = gimple_build_nop ();
3247 unlink_stmt_vdef (stmt);
3248 release_defs (stmt);
3252 new_stmt = gimple_build_assign (lhs, tmp);
3253 gimple_set_vuse (new_stmt, gimple_vuse (stmt));
3254 gimple_set_vdef (new_stmt, gimple_vdef (stmt));
3255 move_ssa_defining_stmt_for_defs (new_stmt, stmt);
3258 gimple_set_location (new_stmt, gimple_location (stmt));
3259 gsi_replace (si_p, new_stmt, false);
3262 /* A simple pass that attempts to fold all builtin functions. This pass
3263 is run after we've propagated as many constants as we can. */
3266 execute_fold_all_builtins (void)
3268 bool cfg_changed = false;
3270 unsigned int todoflags = 0;
3274 gimple_stmt_iterator i;
3275 for (i = gsi_start_bb (bb); !gsi_end_p (i); )
3277 gimple stmt, old_stmt;
3278 tree callee, result;
3279 enum built_in_function fcode;
3281 stmt = gsi_stmt (i);
3283 if (gimple_code (stmt) != GIMPLE_CALL)
3288 callee = gimple_call_fndecl (stmt);
3289 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
3294 fcode = DECL_FUNCTION_CODE (callee);
3296 result = ccp_fold_builtin (stmt);
3299 gimple_remove_stmt_histograms (cfun, stmt);
3302 switch (DECL_FUNCTION_CODE (callee))
3304 case BUILT_IN_CONSTANT_P:
3305 /* Resolve __builtin_constant_p. If it hasn't been
3306 folded to integer_one_node by now, it's fairly
3307 certain that the value simply isn't constant. */
3308 result = integer_zero_node;
3311 case BUILT_IN_STACK_RESTORE:
3312 result = optimize_stack_restore (i);
3318 case BUILT_IN_VA_START:
3319 case BUILT_IN_VA_END:
3320 case BUILT_IN_VA_COPY:
3321 /* These shouldn't be folded before pass_stdarg. */
3322 result = optimize_stdarg_builtin (stmt);
3332 if (dump_file && (dump_flags & TDF_DETAILS))
3334 fprintf (dump_file, "Simplified\n ");
3335 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
3339 if (!update_call_from_tree (&i, result))
3341 gimplify_and_update_call_from_tree (&i, result);
3342 todoflags |= TODO_update_address_taken;
3345 stmt = gsi_stmt (i);
3348 if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt)
3349 && gimple_purge_dead_eh_edges (bb))
3352 if (dump_file && (dump_flags & TDF_DETAILS))
3354 fprintf (dump_file, "to\n ");
3355 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
3356 fprintf (dump_file, "\n");
3359 /* Retry the same statement if it changed into another
3360 builtin, there might be new opportunities now. */
3361 if (gimple_code (stmt) != GIMPLE_CALL)
3366 callee = gimple_call_fndecl (stmt);
3368 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
3369 || DECL_FUNCTION_CODE (callee) == fcode)
3374 /* Delete unreachable blocks. */
3376 todoflags |= TODO_cleanup_cfg;
3382 struct gimple_opt_pass pass_fold_builtins =
3388 execute_fold_all_builtins, /* execute */
3391 0, /* static_pass_number */
3392 TV_NONE, /* tv_id */
3393 PROP_cfg | PROP_ssa, /* properties_required */
3394 0, /* properties_provided */
3395 0, /* properties_destroyed */
3396 0, /* todo_flags_start */
3399 | TODO_update_ssa /* todo_flags_finish */