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)
280 || TREE_CODE (sym) == CONST_DECL))
282 tree val = DECL_INITIAL (sym);
285 STRIP_USELESS_TYPE_CONVERSION (val);
286 if (is_gimple_min_invariant (val))
288 if (TREE_CODE (val) == ADDR_EXPR)
290 tree base = get_base_address (TREE_OPERAND (val, 0));
291 if (base && TREE_CODE (base) == VAR_DECL)
293 TREE_ADDRESSABLE (base) = 1;
294 if (gimple_referenced_vars (cfun))
295 add_referenced_var (base);
301 /* Variables declared 'const' without an initializer
302 have zero as the initializer if they may not be
303 overridden at link or run time. */
305 && !DECL_EXTERNAL (sym)
306 && targetm.binds_local_p (sym)
307 && (INTEGRAL_TYPE_P (TREE_TYPE (sym))
308 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (sym))))
309 return fold_convert (TREE_TYPE (sym), integer_zero_node);
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- Variables defined by statements other than assignments and PHI
328 nodes are considered VARYING.
330 4- Initial values of variables that are not GIMPLE registers are
331 considered VARYING. */
334 get_default_value (tree var)
336 tree sym = SSA_NAME_VAR (var);
337 prop_value_t val = { UNINITIALIZED, NULL_TREE };
340 stmt = SSA_NAME_DEF_STMT (var);
342 if (gimple_nop_p (stmt))
344 /* Variables defined by an empty statement are those used
345 before being initialized. If VAR is a local variable, we
346 can assume initially that it is UNDEFINED, otherwise we must
347 consider it VARYING. */
348 if (is_gimple_reg (sym) && TREE_CODE (sym) != PARM_DECL)
349 val.lattice_val = UNDEFINED;
351 val.lattice_val = VARYING;
353 else if (is_gimple_assign (stmt)
354 /* Value-returning GIMPLE_CALL statements assign to
355 a variable, and are treated similarly to GIMPLE_ASSIGN. */
356 || (is_gimple_call (stmt)
357 && gimple_call_lhs (stmt) != NULL_TREE)
358 || gimple_code (stmt) == GIMPLE_PHI)
361 if (gimple_assign_single_p (stmt)
362 && DECL_P (gimple_assign_rhs1 (stmt))
363 && (cst = get_symbol_constant_value (gimple_assign_rhs1 (stmt))))
365 val.lattice_val = CONSTANT;
369 /* Any other variable defined by an assignment or a PHI node
370 is considered UNDEFINED. */
371 val.lattice_val = UNDEFINED;
375 /* Otherwise, VAR will never take on a constant value. */
376 val.lattice_val = VARYING;
383 /* Get the constant value associated with variable VAR. */
385 static inline prop_value_t *
390 if (const_val == NULL)
393 val = &const_val[SSA_NAME_VERSION (var)];
394 if (val->lattice_val == UNINITIALIZED)
395 *val = get_default_value (var);
397 canonicalize_float_value (val);
402 /* Sets the value associated with VAR to VARYING. */
405 set_value_varying (tree var)
407 prop_value_t *val = &const_val[SSA_NAME_VERSION (var)];
409 val->lattice_val = VARYING;
410 val->value = NULL_TREE;
413 /* For float types, modify the value of VAL to make ccp work correctly
414 for non-standard values (-0, NaN):
416 If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0.
417 If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED.
418 This is to fix the following problem (see PR 29921): Suppose we have
422 and we set value of y to NaN. This causes value of x to be set to NaN.
423 When we later determine that y is in fact VARYING, fold uses the fact
424 that HONOR_NANS is false, and we try to change the value of x to 0,
425 causing an ICE. With HONOR_NANS being false, the real appearance of
426 NaN would cause undefined behavior, though, so claiming that y (and x)
427 are UNDEFINED initially is correct. */
430 canonicalize_float_value (prop_value_t *val)
432 enum machine_mode mode;
436 if (val->lattice_val != CONSTANT
437 || TREE_CODE (val->value) != REAL_CST)
440 d = TREE_REAL_CST (val->value);
441 type = TREE_TYPE (val->value);
442 mode = TYPE_MODE (type);
444 if (!HONOR_SIGNED_ZEROS (mode)
445 && REAL_VALUE_MINUS_ZERO (d))
447 val->value = build_real (type, dconst0);
451 if (!HONOR_NANS (mode)
452 && REAL_VALUE_ISNAN (d))
454 val->lattice_val = UNDEFINED;
460 /* Set the value for variable VAR to NEW_VAL. Return true if the new
461 value is different from VAR's previous value. */
464 set_lattice_value (tree var, prop_value_t new_val)
466 prop_value_t *old_val = get_value (var);
468 canonicalize_float_value (&new_val);
470 /* Lattice transitions must always be monotonically increasing in
471 value. If *OLD_VAL and NEW_VAL are the same, return false to
472 inform the caller that this was a non-transition. */
474 gcc_assert (old_val->lattice_val < new_val.lattice_val
475 || (old_val->lattice_val == new_val.lattice_val
476 && ((!old_val->value && !new_val.value)
477 || operand_equal_p (old_val->value, new_val.value, 0))));
479 if (old_val->lattice_val != new_val.lattice_val)
481 if (dump_file && (dump_flags & TDF_DETAILS))
483 dump_lattice_value (dump_file, "Lattice value changed to ", new_val);
484 fprintf (dump_file, ". Adding SSA edges to worklist.\n");
489 gcc_assert (new_val.lattice_val != UNDEFINED);
497 /* Return the likely CCP lattice value for STMT.
499 If STMT has no operands, then return CONSTANT.
501 Else if undefinedness of operands of STMT cause its value to be
502 undefined, then return UNDEFINED.
504 Else if any operands of STMT are constants, then return CONSTANT.
506 Else return VARYING. */
509 likely_value (gimple stmt)
511 bool has_constant_operand, has_undefined_operand, all_undefined_operands;
516 enum gimple_code code = gimple_code (stmt);
518 /* This function appears to be called only for assignments, calls,
519 conditionals, and switches, due to the logic in visit_stmt. */
520 gcc_assert (code == GIMPLE_ASSIGN
521 || code == GIMPLE_CALL
522 || code == GIMPLE_COND
523 || code == GIMPLE_SWITCH);
525 /* If the statement has volatile operands, it won't fold to a
527 if (gimple_has_volatile_ops (stmt))
530 /* Arrive here for more complex cases. */
531 has_constant_operand = false;
532 has_undefined_operand = false;
533 all_undefined_operands = true;
534 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE)
536 prop_value_t *val = get_value (use);
538 if (val->lattice_val == UNDEFINED)
539 has_undefined_operand = true;
541 all_undefined_operands = false;
543 if (val->lattice_val == CONSTANT)
544 has_constant_operand = true;
547 /* There may be constants in regular rhs operands. For calls we
548 have to ignore lhs, fndecl and static chain, otherwise only
550 for (i = (is_gimple_call (stmt) ? 2 : 0) + gimple_has_lhs (stmt);
551 i < gimple_num_ops (stmt); ++i)
553 tree op = gimple_op (stmt, i);
554 if (!op || TREE_CODE (op) == SSA_NAME)
556 if (is_gimple_min_invariant (op))
557 has_constant_operand = true;
560 /* If the operation combines operands like COMPLEX_EXPR make sure to
561 not mark the result UNDEFINED if only one part of the result is
563 if (has_undefined_operand && all_undefined_operands)
565 else if (code == GIMPLE_ASSIGN && has_undefined_operand)
567 switch (gimple_assign_rhs_code (stmt))
569 /* Unary operators are handled with all_undefined_operands. */
572 case POINTER_PLUS_EXPR:
573 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected.
574 Not bitwise operators, one VARYING operand may specify the
575 result completely. Not logical operators for the same reason.
576 Not COMPLEX_EXPR as one VARYING operand makes the result partly
577 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because
578 the undefined operand may be promoted. */
585 /* If there was an UNDEFINED operand but the result may be not UNDEFINED
586 fall back to VARYING even if there were CONSTANT operands. */
587 if (has_undefined_operand)
590 /* We do not consider virtual operands here -- load from read-only
591 memory may have only VARYING virtual operands, but still be
593 if (has_constant_operand
594 || gimple_references_memory_p (stmt))
600 /* Returns true if STMT cannot be constant. */
603 surely_varying_stmt_p (gimple stmt)
605 /* If the statement has operands that we cannot handle, it cannot be
607 if (gimple_has_volatile_ops (stmt))
610 /* If it is a call and does not return a value or is not a
611 builtin and not an indirect call, it is varying. */
612 if (is_gimple_call (stmt))
615 if (!gimple_call_lhs (stmt)
616 || ((fndecl = gimple_call_fndecl (stmt)) != NULL_TREE
617 && !DECL_BUILT_IN (fndecl)))
621 /* Any other store operation is not interesting. */
622 else if (gimple_vdef (stmt))
625 /* Anything other than assignments and conditional jumps are not
626 interesting for CCP. */
627 if (gimple_code (stmt) != GIMPLE_ASSIGN
628 && gimple_code (stmt) != GIMPLE_COND
629 && gimple_code (stmt) != GIMPLE_SWITCH
630 && gimple_code (stmt) != GIMPLE_CALL)
636 /* Initialize local data structures for CCP. */
639 ccp_initialize (void)
643 const_val = XCNEWVEC (prop_value_t, num_ssa_names);
645 /* Initialize simulation flags for PHI nodes and statements. */
648 gimple_stmt_iterator i;
650 for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i))
652 gimple stmt = gsi_stmt (i);
653 bool is_varying = surely_varying_stmt_p (stmt);
660 /* If the statement will not produce a constant, mark
661 all its outputs VARYING. */
662 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
663 set_value_varying (def);
665 prop_set_simulate_again (stmt, !is_varying);
669 /* Now process PHI nodes. We never clear the simulate_again flag on
670 phi nodes, since we do not know which edges are executable yet,
671 except for phi nodes for virtual operands when we do not do store ccp. */
674 gimple_stmt_iterator i;
676 for (i = gsi_start_phis (bb); !gsi_end_p (i); gsi_next (&i))
678 gimple phi = gsi_stmt (i);
680 if (!is_gimple_reg (gimple_phi_result (phi)))
681 prop_set_simulate_again (phi, false);
683 prop_set_simulate_again (phi, true);
688 /* Debug count support. Reset the values of ssa names
689 VARYING when the total number ssa names analyzed is
690 beyond the debug count specified. */
696 for (i = 0; i < num_ssa_names; i++)
700 const_val[i].lattice_val = VARYING;
701 const_val[i].value = NULL_TREE;
707 /* Do final substitution of propagated values, cleanup the flowgraph and
708 free allocated storage.
710 Return TRUE when something was optimized. */
715 bool something_changed;
718 /* Perform substitutions based on the known constant values. */
719 something_changed = substitute_and_fold (const_val, false);
723 return something_changed;;
727 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
730 any M UNDEFINED = any
731 any M VARYING = VARYING
732 Ci M Cj = Ci if (i == j)
733 Ci M Cj = VARYING if (i != j)
737 ccp_lattice_meet (prop_value_t *val1, prop_value_t *val2)
739 if (val1->lattice_val == UNDEFINED)
741 /* UNDEFINED M any = any */
744 else if (val2->lattice_val == UNDEFINED)
746 /* any M UNDEFINED = any
747 Nothing to do. VAL1 already contains the value we want. */
750 else if (val1->lattice_val == VARYING
751 || val2->lattice_val == VARYING)
753 /* any M VARYING = VARYING. */
754 val1->lattice_val = VARYING;
755 val1->value = NULL_TREE;
757 else if (val1->lattice_val == CONSTANT
758 && val2->lattice_val == CONSTANT
759 && simple_cst_equal (val1->value, val2->value) == 1)
761 /* Ci M Cj = Ci if (i == j)
762 Ci M Cj = VARYING if (i != j)
764 If these two values come from memory stores, make sure that
765 they come from the same memory reference. */
766 val1->lattice_val = CONSTANT;
767 val1->value = val1->value;
771 /* Any other combination is VARYING. */
772 val1->lattice_val = VARYING;
773 val1->value = NULL_TREE;
778 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
779 lattice values to determine PHI_NODE's lattice value. The value of a
780 PHI node is determined calling ccp_lattice_meet with all the arguments
781 of the PHI node that are incoming via executable edges. */
783 static enum ssa_prop_result
784 ccp_visit_phi_node (gimple phi)
787 prop_value_t *old_val, new_val;
789 if (dump_file && (dump_flags & TDF_DETAILS))
791 fprintf (dump_file, "\nVisiting PHI node: ");
792 print_gimple_stmt (dump_file, phi, 0, dump_flags);
795 old_val = get_value (gimple_phi_result (phi));
796 switch (old_val->lattice_val)
799 return SSA_PROP_VARYING;
806 new_val.lattice_val = UNDEFINED;
807 new_val.value = NULL_TREE;
814 for (i = 0; i < gimple_phi_num_args (phi); i++)
816 /* Compute the meet operator over all the PHI arguments flowing
817 through executable edges. */
818 edge e = gimple_phi_arg_edge (phi, i);
820 if (dump_file && (dump_flags & TDF_DETAILS))
823 "\n Argument #%d (%d -> %d %sexecutable)\n",
824 i, e->src->index, e->dest->index,
825 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
828 /* If the incoming edge is executable, Compute the meet operator for
829 the existing value of the PHI node and the current PHI argument. */
830 if (e->flags & EDGE_EXECUTABLE)
832 tree arg = gimple_phi_arg (phi, i)->def;
833 prop_value_t arg_val;
835 if (is_gimple_min_invariant (arg))
837 arg_val.lattice_val = CONSTANT;
841 arg_val = *(get_value (arg));
843 ccp_lattice_meet (&new_val, &arg_val);
845 if (dump_file && (dump_flags & TDF_DETAILS))
847 fprintf (dump_file, "\t");
848 print_generic_expr (dump_file, arg, dump_flags);
849 dump_lattice_value (dump_file, "\tValue: ", arg_val);
850 fprintf (dump_file, "\n");
853 if (new_val.lattice_val == VARYING)
858 if (dump_file && (dump_flags & TDF_DETAILS))
860 dump_lattice_value (dump_file, "\n PHI node value: ", new_val);
861 fprintf (dump_file, "\n\n");
864 /* Make the transition to the new value. */
865 if (set_lattice_value (gimple_phi_result (phi), new_val))
867 if (new_val.lattice_val == VARYING)
868 return SSA_PROP_VARYING;
870 return SSA_PROP_INTERESTING;
873 return SSA_PROP_NOT_INTERESTING;
876 /* Return true if we may propagate the address expression ADDR into the
877 dereference DEREF and cancel them. */
880 may_propagate_address_into_dereference (tree addr, tree deref)
882 gcc_assert (INDIRECT_REF_P (deref)
883 && TREE_CODE (addr) == ADDR_EXPR);
885 /* Don't propagate if ADDR's operand has incomplete type. */
886 if (!COMPLETE_TYPE_P (TREE_TYPE (TREE_OPERAND (addr, 0))))
889 /* If the address is invariant then we do not need to preserve restrict
890 qualifications. But we do need to preserve volatile qualifiers until
891 we can annotate the folded dereference itself properly. */
892 if (is_gimple_min_invariant (addr)
893 && (!TREE_THIS_VOLATILE (deref)
894 || TYPE_VOLATILE (TREE_TYPE (addr))))
895 return useless_type_conversion_p (TREE_TYPE (deref),
896 TREE_TYPE (TREE_OPERAND (addr, 0)));
898 /* Else both the address substitution and the folding must result in
899 a valid useless type conversion sequence. */
900 return (useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (deref, 0)),
902 && useless_type_conversion_p (TREE_TYPE (deref),
903 TREE_TYPE (TREE_OPERAND (addr, 0))));
906 /* CCP specific front-end to the non-destructive constant folding
909 Attempt to simplify the RHS of STMT knowing that one or more
910 operands are constants.
912 If simplification is possible, return the simplified RHS,
913 otherwise return the original RHS or NULL_TREE. */
916 ccp_fold (gimple stmt)
918 location_t loc = gimple_location (stmt);
919 switch (gimple_code (stmt))
923 enum tree_code subcode = gimple_assign_rhs_code (stmt);
925 switch (get_gimple_rhs_class (subcode))
927 case GIMPLE_SINGLE_RHS:
929 tree rhs = gimple_assign_rhs1 (stmt);
930 enum tree_code_class kind = TREE_CODE_CLASS (subcode);
932 if (TREE_CODE (rhs) == SSA_NAME)
934 /* If the RHS is an SSA_NAME, return its known constant value,
936 return get_value (rhs)->value;
938 /* Handle propagating invariant addresses into address operations.
939 The folding we do here matches that in tree-ssa-forwprop.c. */
940 else if (TREE_CODE (rhs) == ADDR_EXPR)
943 base = &TREE_OPERAND (rhs, 0);
944 while (handled_component_p (*base))
945 base = &TREE_OPERAND (*base, 0);
946 if (TREE_CODE (*base) == INDIRECT_REF
947 && TREE_CODE (TREE_OPERAND (*base, 0)) == SSA_NAME)
949 prop_value_t *val = get_value (TREE_OPERAND (*base, 0));
950 if (val->lattice_val == CONSTANT
951 && TREE_CODE (val->value) == ADDR_EXPR
952 && may_propagate_address_into_dereference
955 /* We need to return a new tree, not modify the IL
956 or share parts of it. So play some tricks to
957 avoid manually building it. */
958 tree ret, save = *base;
959 *base = TREE_OPERAND (val->value, 0);
960 ret = unshare_expr (rhs);
961 recompute_tree_invariant_for_addr_expr (ret);
967 else if (TREE_CODE (rhs) == CONSTRUCTOR
968 && TREE_CODE (TREE_TYPE (rhs)) == VECTOR_TYPE
969 && (CONSTRUCTOR_NELTS (rhs)
970 == TYPE_VECTOR_SUBPARTS (TREE_TYPE (rhs))))
976 FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (rhs), i, val)
978 if (TREE_CODE (val) == SSA_NAME
979 && get_value (val)->lattice_val == CONSTANT)
980 val = get_value (val)->value;
981 if (TREE_CODE (val) == INTEGER_CST
982 || TREE_CODE (val) == REAL_CST
983 || TREE_CODE (val) == FIXED_CST)
984 list = tree_cons (NULL_TREE, val, list);
989 return build_vector (TREE_TYPE (rhs), nreverse (list));
992 if (kind == tcc_reference)
994 if ((TREE_CODE (rhs) == VIEW_CONVERT_EXPR
995 || TREE_CODE (rhs) == REALPART_EXPR
996 || TREE_CODE (rhs) == IMAGPART_EXPR)
997 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
999 prop_value_t *val = get_value (TREE_OPERAND (rhs, 0));
1000 if (val->lattice_val == CONSTANT)
1001 return fold_unary_loc (EXPR_LOCATION (rhs),
1003 TREE_TYPE (rhs), val->value);
1005 else if (TREE_CODE (rhs) == INDIRECT_REF
1006 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
1008 prop_value_t *val = get_value (TREE_OPERAND (rhs, 0));
1009 if (val->lattice_val == CONSTANT
1010 && TREE_CODE (val->value) == ADDR_EXPR
1011 && useless_type_conversion_p (TREE_TYPE (rhs),
1012 TREE_TYPE (TREE_TYPE (val->value))))
1013 rhs = TREE_OPERAND (val->value, 0);
1015 return fold_const_aggregate_ref (rhs);
1017 else if (kind == tcc_declaration)
1018 return get_symbol_constant_value (rhs);
1022 case GIMPLE_UNARY_RHS:
1024 /* Handle unary operators that can appear in GIMPLE form.
1025 Note that we know the single operand must be a constant,
1026 so this should almost always return a simplified RHS. */
1027 tree lhs = gimple_assign_lhs (stmt);
1028 tree op0 = gimple_assign_rhs1 (stmt);
1030 /* Simplify the operand down to a constant. */
1031 if (TREE_CODE (op0) == SSA_NAME)
1033 prop_value_t *val = get_value (op0);
1034 if (val->lattice_val == CONSTANT)
1035 op0 = get_value (op0)->value;
1038 /* Conversions are useless for CCP purposes if they are
1039 value-preserving. Thus the restrictions that
1040 useless_type_conversion_p places for pointer type conversions
1041 do not apply here. Substitution later will only substitute to
1043 if (CONVERT_EXPR_CODE_P (subcode)
1044 && POINTER_TYPE_P (TREE_TYPE (lhs))
1045 && POINTER_TYPE_P (TREE_TYPE (op0))
1046 /* Do not allow differences in volatile qualification
1047 as this might get us confused as to whether a
1048 propagation destination statement is volatile
1049 or not. See PR36988. */
1050 && (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (lhs)))
1051 == TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (op0)))))
1054 /* Still try to generate a constant of correct type. */
1055 if (!useless_type_conversion_p (TREE_TYPE (lhs),
1057 && ((tem = maybe_fold_offset_to_address
1059 op0, integer_zero_node, TREE_TYPE (lhs)))
1066 fold_unary_ignore_overflow_loc (loc, subcode,
1067 gimple_expr_type (stmt), op0);
1070 case GIMPLE_BINARY_RHS:
1072 /* Handle binary operators that can appear in GIMPLE form. */
1073 tree op0 = gimple_assign_rhs1 (stmt);
1074 tree op1 = gimple_assign_rhs2 (stmt);
1076 /* Simplify the operands down to constants when appropriate. */
1077 if (TREE_CODE (op0) == SSA_NAME)
1079 prop_value_t *val = get_value (op0);
1080 if (val->lattice_val == CONSTANT)
1084 if (TREE_CODE (op1) == SSA_NAME)
1086 prop_value_t *val = get_value (op1);
1087 if (val->lattice_val == CONSTANT)
1091 /* Fold &foo + CST into an invariant reference if possible. */
1092 if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR
1093 && TREE_CODE (op0) == ADDR_EXPR
1094 && TREE_CODE (op1) == INTEGER_CST)
1096 tree lhs = gimple_assign_lhs (stmt);
1097 tree tem = maybe_fold_offset_to_address
1098 (loc, op0, op1, TREE_TYPE (lhs));
1099 if (tem != NULL_TREE)
1103 return fold_binary_loc (loc, subcode,
1104 gimple_expr_type (stmt), op0, op1);
1115 tree fn = gimple_call_fn (stmt);
1118 if (TREE_CODE (fn) == SSA_NAME)
1120 val = get_value (fn);
1121 if (val->lattice_val == CONSTANT)
1124 if (TREE_CODE (fn) == ADDR_EXPR
1125 && TREE_CODE (TREE_OPERAND (fn, 0)) == FUNCTION_DECL
1126 && DECL_BUILT_IN (TREE_OPERAND (fn, 0)))
1128 tree *args = XALLOCAVEC (tree, gimple_call_num_args (stmt));
1131 for (i = 0; i < gimple_call_num_args (stmt); ++i)
1133 args[i] = gimple_call_arg (stmt, i);
1134 if (TREE_CODE (args[i]) == SSA_NAME)
1136 val = get_value (args[i]);
1137 if (val->lattice_val == CONSTANT)
1138 args[i] = val->value;
1141 call = build_call_array_loc (loc,
1142 gimple_call_return_type (stmt),
1143 fn, gimple_call_num_args (stmt), args);
1144 retval = fold_call_expr (EXPR_LOCATION (call), call, false);
1146 /* fold_call_expr wraps the result inside a NOP_EXPR. */
1147 STRIP_NOPS (retval);
1155 /* Handle comparison operators that can appear in GIMPLE form. */
1156 tree op0 = gimple_cond_lhs (stmt);
1157 tree op1 = gimple_cond_rhs (stmt);
1158 enum tree_code code = gimple_cond_code (stmt);
1160 /* Simplify the operands down to constants when appropriate. */
1161 if (TREE_CODE (op0) == SSA_NAME)
1163 prop_value_t *val = get_value (op0);
1164 if (val->lattice_val == CONSTANT)
1168 if (TREE_CODE (op1) == SSA_NAME)
1170 prop_value_t *val = get_value (op1);
1171 if (val->lattice_val == CONSTANT)
1175 return fold_binary_loc (loc, code, boolean_type_node, op0, op1);
1180 tree rhs = gimple_switch_index (stmt);
1182 if (TREE_CODE (rhs) == SSA_NAME)
1184 /* If the RHS is an SSA_NAME, return its known constant value,
1186 return get_value (rhs)->value;
1198 /* Return the tree representing the element referenced by T if T is an
1199 ARRAY_REF or COMPONENT_REF into constant aggregates. Return
1200 NULL_TREE otherwise. */
1203 fold_const_aggregate_ref (tree t)
1205 prop_value_t *value;
1206 tree base, ctor, idx, field;
1207 unsigned HOST_WIDE_INT cnt;
1210 if (TREE_CODE_CLASS (TREE_CODE (t)) == tcc_declaration)
1211 return get_symbol_constant_value (t);
1213 switch (TREE_CODE (t))
1216 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1217 DECL_INITIAL. If BASE is a nested reference into another
1218 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1219 the inner reference. */
1220 base = TREE_OPERAND (t, 0);
1221 switch (TREE_CODE (base))
1224 if (!TREE_READONLY (base)
1225 || TREE_CODE (TREE_TYPE (base)) != ARRAY_TYPE
1226 || !targetm.binds_local_p (base))
1229 ctor = DECL_INITIAL (base);
1234 ctor = fold_const_aggregate_ref (base);
1246 if (ctor == NULL_TREE
1247 || (TREE_CODE (ctor) != CONSTRUCTOR
1248 && TREE_CODE (ctor) != STRING_CST)
1249 || !TREE_STATIC (ctor))
1252 /* Get the index. If we have an SSA_NAME, try to resolve it
1253 with the current lattice value for the SSA_NAME. */
1254 idx = TREE_OPERAND (t, 1);
1255 switch (TREE_CODE (idx))
1258 if ((value = get_value (idx))
1259 && value->lattice_val == CONSTANT
1260 && TREE_CODE (value->value) == INTEGER_CST)
1273 /* Fold read from constant string. */
1274 if (TREE_CODE (ctor) == STRING_CST)
1276 if ((TYPE_MODE (TREE_TYPE (t))
1277 == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1278 && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1280 && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) == 1
1281 && compare_tree_int (idx, TREE_STRING_LENGTH (ctor)) < 0)
1282 return build_int_cst_type (TREE_TYPE (t),
1283 (TREE_STRING_POINTER (ctor)
1284 [TREE_INT_CST_LOW (idx)]));
1288 /* Whoo-hoo! I'll fold ya baby. Yeah! */
1289 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
1290 if (tree_int_cst_equal (cfield, idx))
1292 STRIP_USELESS_TYPE_CONVERSION (cval);
1293 if (TREE_CODE (cval) == ADDR_EXPR)
1295 tree base = get_base_address (TREE_OPERAND (cval, 0));
1296 if (base && TREE_CODE (base) == VAR_DECL)
1297 add_referenced_var (base);
1304 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1305 DECL_INITIAL. If BASE is a nested reference into another
1306 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1307 the inner reference. */
1308 base = TREE_OPERAND (t, 0);
1309 switch (TREE_CODE (base))
1312 if (!TREE_READONLY (base)
1313 || TREE_CODE (TREE_TYPE (base)) != RECORD_TYPE
1314 || !targetm.binds_local_p (base))
1317 ctor = DECL_INITIAL (base);
1322 ctor = fold_const_aggregate_ref (base);
1329 if (ctor == NULL_TREE
1330 || TREE_CODE (ctor) != CONSTRUCTOR
1331 || !TREE_STATIC (ctor))
1334 field = TREE_OPERAND (t, 1);
1336 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
1338 /* FIXME: Handle bit-fields. */
1339 && ! DECL_BIT_FIELD (cfield))
1341 STRIP_USELESS_TYPE_CONVERSION (cval);
1342 if (TREE_CODE (cval) == ADDR_EXPR)
1344 tree base = get_base_address (TREE_OPERAND (cval, 0));
1345 if (base && TREE_CODE (base) == VAR_DECL)
1346 add_referenced_var (base);
1355 tree c = fold_const_aggregate_ref (TREE_OPERAND (t, 0));
1356 if (c && TREE_CODE (c) == COMPLEX_CST)
1357 return fold_build1_loc (EXPR_LOCATION (t),
1358 TREE_CODE (t), TREE_TYPE (t), c);
1364 tree base = TREE_OPERAND (t, 0);
1365 if (TREE_CODE (base) == SSA_NAME
1366 && (value = get_value (base))
1367 && value->lattice_val == CONSTANT
1368 && TREE_CODE (value->value) == ADDR_EXPR
1369 && useless_type_conversion_p (TREE_TYPE (t),
1370 TREE_TYPE (TREE_TYPE (value->value))))
1371 return fold_const_aggregate_ref (TREE_OPERAND (value->value, 0));
1382 /* Evaluate statement STMT.
1383 Valid only for assignments, calls, conditionals, and switches. */
1386 evaluate_stmt (gimple stmt)
1389 tree simplified = NULL_TREE;
1390 ccp_lattice_t likelyvalue = likely_value (stmt);
1393 fold_defer_overflow_warnings ();
1395 /* If the statement is likely to have a CONSTANT result, then try
1396 to fold the statement to determine the constant value. */
1397 /* FIXME. This is the only place that we call ccp_fold.
1398 Since likely_value never returns CONSTANT for calls, we will
1399 not attempt to fold them, including builtins that may profit. */
1400 if (likelyvalue == CONSTANT)
1401 simplified = ccp_fold (stmt);
1402 /* If the statement is likely to have a VARYING result, then do not
1403 bother folding the statement. */
1404 else if (likelyvalue == VARYING)
1406 enum gimple_code code = gimple_code (stmt);
1407 if (code == GIMPLE_ASSIGN)
1409 enum tree_code subcode = gimple_assign_rhs_code (stmt);
1411 /* Other cases cannot satisfy is_gimple_min_invariant
1413 if (get_gimple_rhs_class (subcode) == GIMPLE_SINGLE_RHS)
1414 simplified = gimple_assign_rhs1 (stmt);
1416 else if (code == GIMPLE_SWITCH)
1417 simplified = gimple_switch_index (stmt);
1419 /* These cannot satisfy is_gimple_min_invariant without folding. */
1420 gcc_assert (code == GIMPLE_CALL || code == GIMPLE_COND);
1423 is_constant = simplified && is_gimple_min_invariant (simplified);
1425 fold_undefer_overflow_warnings (is_constant, stmt, 0);
1427 if (dump_file && (dump_flags & TDF_DETAILS))
1429 fprintf (dump_file, "which is likely ");
1430 switch (likelyvalue)
1433 fprintf (dump_file, "CONSTANT");
1436 fprintf (dump_file, "UNDEFINED");
1439 fprintf (dump_file, "VARYING");
1443 fprintf (dump_file, "\n");
1448 /* The statement produced a constant value. */
1449 val.lattice_val = CONSTANT;
1450 val.value = simplified;
1454 /* The statement produced a nonconstant value. If the statement
1455 had UNDEFINED operands, then the result of the statement
1456 should be UNDEFINED. Otherwise, the statement is VARYING. */
1457 if (likelyvalue == UNDEFINED)
1458 val.lattice_val = likelyvalue;
1460 val.lattice_val = VARYING;
1462 val.value = NULL_TREE;
1468 /* Visit the assignment statement STMT. Set the value of its LHS to the
1469 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
1470 creates virtual definitions, set the value of each new name to that
1471 of the RHS (if we can derive a constant out of the RHS).
1472 Value-returning call statements also perform an assignment, and
1473 are handled here. */
1475 static enum ssa_prop_result
1476 visit_assignment (gimple stmt, tree *output_p)
1479 enum ssa_prop_result retval;
1481 tree lhs = gimple_get_lhs (stmt);
1483 gcc_assert (gimple_code (stmt) != GIMPLE_CALL
1484 || gimple_call_lhs (stmt) != NULL_TREE);
1486 if (gimple_assign_copy_p (stmt))
1488 tree rhs = gimple_assign_rhs1 (stmt);
1490 if (TREE_CODE (rhs) == SSA_NAME)
1492 /* For a simple copy operation, we copy the lattice values. */
1493 prop_value_t *nval = get_value (rhs);
1497 val = evaluate_stmt (stmt);
1500 /* Evaluate the statement, which could be
1501 either a GIMPLE_ASSIGN or a GIMPLE_CALL. */
1502 val = evaluate_stmt (stmt);
1504 retval = SSA_PROP_NOT_INTERESTING;
1506 /* Set the lattice value of the statement's output. */
1507 if (TREE_CODE (lhs) == SSA_NAME)
1509 /* If STMT is an assignment to an SSA_NAME, we only have one
1511 if (set_lattice_value (lhs, val))
1514 if (val.lattice_val == VARYING)
1515 retval = SSA_PROP_VARYING;
1517 retval = SSA_PROP_INTERESTING;
1525 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
1526 if it can determine which edge will be taken. Otherwise, return
1527 SSA_PROP_VARYING. */
1529 static enum ssa_prop_result
1530 visit_cond_stmt (gimple stmt, edge *taken_edge_p)
1535 block = gimple_bb (stmt);
1536 val = evaluate_stmt (stmt);
1538 /* Find which edge out of the conditional block will be taken and add it
1539 to the worklist. If no single edge can be determined statically,
1540 return SSA_PROP_VARYING to feed all the outgoing edges to the
1541 propagation engine. */
1542 *taken_edge_p = val.value ? find_taken_edge (block, val.value) : 0;
1544 return SSA_PROP_INTERESTING;
1546 return SSA_PROP_VARYING;
1550 /* Evaluate statement STMT. If the statement produces an output value and
1551 its evaluation changes the lattice value of its output, return
1552 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
1555 If STMT is a conditional branch and we can determine its truth
1556 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
1557 value, return SSA_PROP_VARYING. */
1559 static enum ssa_prop_result
1560 ccp_visit_stmt (gimple stmt, edge *taken_edge_p, tree *output_p)
1565 if (dump_file && (dump_flags & TDF_DETAILS))
1567 fprintf (dump_file, "\nVisiting statement:\n");
1568 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
1571 switch (gimple_code (stmt))
1574 /* If the statement is an assignment that produces a single
1575 output value, evaluate its RHS to see if the lattice value of
1576 its output has changed. */
1577 return visit_assignment (stmt, output_p);
1580 /* A value-returning call also performs an assignment. */
1581 if (gimple_call_lhs (stmt) != NULL_TREE)
1582 return visit_assignment (stmt, output_p);
1587 /* If STMT is a conditional branch, see if we can determine
1588 which branch will be taken. */
1589 /* FIXME. It appears that we should be able to optimize
1590 computed GOTOs here as well. */
1591 return visit_cond_stmt (stmt, taken_edge_p);
1597 /* Any other kind of statement is not interesting for constant
1598 propagation and, therefore, not worth simulating. */
1599 if (dump_file && (dump_flags & TDF_DETAILS))
1600 fprintf (dump_file, "No interesting values produced. Marked VARYING.\n");
1602 /* Definitions made by statements other than assignments to
1603 SSA_NAMEs represent unknown modifications to their outputs.
1604 Mark them VARYING. */
1605 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
1607 prop_value_t v = { VARYING, NULL_TREE };
1608 set_lattice_value (def, v);
1611 return SSA_PROP_VARYING;
1615 /* Main entry point for SSA Conditional Constant Propagation. */
1621 ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node);
1622 if (ccp_finalize ())
1623 return (TODO_cleanup_cfg | TODO_update_ssa | TODO_remove_unused_locals);
1632 return flag_tree_ccp != 0;
1636 struct gimple_opt_pass pass_ccp =
1641 gate_ccp, /* gate */
1642 do_ssa_ccp, /* execute */
1645 0, /* static_pass_number */
1646 TV_TREE_CCP, /* tv_id */
1647 PROP_cfg | PROP_ssa, /* properties_required */
1648 0, /* properties_provided */
1649 0, /* properties_destroyed */
1650 0, /* todo_flags_start */
1651 TODO_dump_func | TODO_verify_ssa
1652 | TODO_verify_stmts | TODO_ggc_collect/* todo_flags_finish */
1657 /* A subroutine of fold_stmt. Attempts to fold *(A+O) to A[X].
1658 BASE is an array type. OFFSET is a byte displacement. ORIG_TYPE
1659 is the desired result type.
1661 LOC is the location of the original expression. */
1664 maybe_fold_offset_to_array_ref (location_t loc, tree base, tree offset,
1666 bool allow_negative_idx)
1668 tree min_idx, idx, idx_type, elt_offset = integer_zero_node;
1669 tree array_type, elt_type, elt_size;
1672 /* If BASE is an ARRAY_REF, we can pick up another offset (this time
1673 measured in units of the size of elements type) from that ARRAY_REF).
1674 We can't do anything if either is variable.
1676 The case we handle here is *(&A[N]+O). */
1677 if (TREE_CODE (base) == ARRAY_REF)
1679 tree low_bound = array_ref_low_bound (base);
1681 elt_offset = TREE_OPERAND (base, 1);
1682 if (TREE_CODE (low_bound) != INTEGER_CST
1683 || TREE_CODE (elt_offset) != INTEGER_CST)
1686 elt_offset = int_const_binop (MINUS_EXPR, elt_offset, low_bound, 0);
1687 base = TREE_OPERAND (base, 0);
1690 /* Ignore stupid user tricks of indexing non-array variables. */
1691 array_type = TREE_TYPE (base);
1692 if (TREE_CODE (array_type) != ARRAY_TYPE)
1694 elt_type = TREE_TYPE (array_type);
1695 if (!useless_type_conversion_p (orig_type, elt_type))
1698 /* Use signed size type for intermediate computation on the index. */
1699 idx_type = signed_type_for (size_type_node);
1701 /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the
1702 element type (so we can use the alignment if it's not constant).
1703 Otherwise, compute the offset as an index by using a division. If the
1704 division isn't exact, then don't do anything. */
1705 elt_size = TYPE_SIZE_UNIT (elt_type);
1708 if (integer_zerop (offset))
1710 if (TREE_CODE (elt_size) != INTEGER_CST)
1711 elt_size = size_int (TYPE_ALIGN (elt_type));
1713 idx = build_int_cst (idx_type, 0);
1717 unsigned HOST_WIDE_INT lquo, lrem;
1718 HOST_WIDE_INT hquo, hrem;
1721 /* The final array offset should be signed, so we need
1722 to sign-extend the (possibly pointer) offset here
1723 and use signed division. */
1724 soffset = double_int_sext (tree_to_double_int (offset),
1725 TYPE_PRECISION (TREE_TYPE (offset)));
1726 if (TREE_CODE (elt_size) != INTEGER_CST
1727 || div_and_round_double (TRUNC_DIV_EXPR, 0,
1728 soffset.low, soffset.high,
1729 TREE_INT_CST_LOW (elt_size),
1730 TREE_INT_CST_HIGH (elt_size),
1731 &lquo, &hquo, &lrem, &hrem)
1735 idx = build_int_cst_wide (idx_type, lquo, hquo);
1738 /* Assume the low bound is zero. If there is a domain type, get the
1739 low bound, if any, convert the index into that type, and add the
1741 min_idx = build_int_cst (idx_type, 0);
1742 domain_type = TYPE_DOMAIN (array_type);
1745 idx_type = domain_type;
1746 if (TYPE_MIN_VALUE (idx_type))
1747 min_idx = TYPE_MIN_VALUE (idx_type);
1749 min_idx = fold_convert (idx_type, min_idx);
1751 if (TREE_CODE (min_idx) != INTEGER_CST)
1754 elt_offset = fold_convert (idx_type, elt_offset);
1757 if (!integer_zerop (min_idx))
1758 idx = int_const_binop (PLUS_EXPR, idx, min_idx, 0);
1759 if (!integer_zerop (elt_offset))
1760 idx = int_const_binop (PLUS_EXPR, idx, elt_offset, 0);
1762 /* Make sure to possibly truncate late after offsetting. */
1763 idx = fold_convert (idx_type, idx);
1765 /* We don't want to construct access past array bounds. For example
1768 should not be simplified into (*c)[14] or tree-vrp will
1769 give false warnings. The same is true for
1770 struct A { long x; char d[0]; } *a;
1772 which should be not folded to &a->d[-8]. */
1774 && TYPE_MAX_VALUE (domain_type)
1775 && TREE_CODE (TYPE_MAX_VALUE (domain_type)) == INTEGER_CST)
1777 tree up_bound = TYPE_MAX_VALUE (domain_type);
1779 if (tree_int_cst_lt (up_bound, idx)
1780 /* Accesses after the end of arrays of size 0 (gcc
1781 extension) and 1 are likely intentional ("struct
1783 && compare_tree_int (up_bound, 1) > 0)
1787 && TYPE_MIN_VALUE (domain_type))
1789 if (!allow_negative_idx
1790 && TREE_CODE (TYPE_MIN_VALUE (domain_type)) == INTEGER_CST
1791 && tree_int_cst_lt (idx, TYPE_MIN_VALUE (domain_type)))
1794 else if (!allow_negative_idx
1795 && compare_tree_int (idx, 0) < 0)
1799 tree t = build4 (ARRAY_REF, elt_type, base, idx, NULL_TREE, NULL_TREE);
1800 SET_EXPR_LOCATION (t, loc);
1806 /* Attempt to fold *(S+O) to S.X.
1807 BASE is a record type. OFFSET is a byte displacement. ORIG_TYPE
1808 is the desired result type.
1810 LOC is the location of the original expression. */
1813 maybe_fold_offset_to_component_ref (location_t loc, tree record_type,
1814 tree base, tree offset,
1815 tree orig_type, bool base_is_ptr)
1817 tree f, t, field_type, tail_array_field, field_offset;
1821 if (TREE_CODE (record_type) != RECORD_TYPE
1822 && TREE_CODE (record_type) != UNION_TYPE
1823 && TREE_CODE (record_type) != QUAL_UNION_TYPE)
1826 /* Short-circuit silly cases. */
1827 if (useless_type_conversion_p (record_type, orig_type))
1830 tail_array_field = NULL_TREE;
1831 for (f = TYPE_FIELDS (record_type); f ; f = TREE_CHAIN (f))
1835 if (TREE_CODE (f) != FIELD_DECL)
1837 if (DECL_BIT_FIELD (f))
1840 if (!DECL_FIELD_OFFSET (f))
1842 field_offset = byte_position (f);
1843 if (TREE_CODE (field_offset) != INTEGER_CST)
1846 /* ??? Java creates "interesting" fields for representing base classes.
1847 They have no name, and have no context. With no context, we get into
1848 trouble with nonoverlapping_component_refs_p. Skip them. */
1849 if (!DECL_FIELD_CONTEXT (f))
1852 /* The previous array field isn't at the end. */
1853 tail_array_field = NULL_TREE;
1855 /* Check to see if this offset overlaps with the field. */
1856 cmp = tree_int_cst_compare (field_offset, offset);
1860 field_type = TREE_TYPE (f);
1862 /* Here we exactly match the offset being checked. If the types match,
1863 then we can return that field. */
1865 && useless_type_conversion_p (orig_type, field_type))
1868 base = build1 (INDIRECT_REF, record_type, base);
1869 t = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE);
1873 /* Don't care about offsets into the middle of scalars. */
1874 if (!AGGREGATE_TYPE_P (field_type))
1877 /* Check for array at the end of the struct. This is often
1878 used as for flexible array members. We should be able to
1879 turn this into an array access anyway. */
1880 if (TREE_CODE (field_type) == ARRAY_TYPE)
1881 tail_array_field = f;
1883 /* Check the end of the field against the offset. */
1884 if (!DECL_SIZE_UNIT (f)
1885 || TREE_CODE (DECL_SIZE_UNIT (f)) != INTEGER_CST)
1887 t = int_const_binop (MINUS_EXPR, offset, field_offset, 1);
1888 if (!tree_int_cst_lt (t, DECL_SIZE_UNIT (f)))
1891 /* If we matched, then set offset to the displacement into
1894 new_base = build1 (INDIRECT_REF, record_type, base);
1897 protected_set_expr_location (new_base, loc);
1898 new_base = build3 (COMPONENT_REF, field_type, new_base, f, NULL_TREE);
1899 protected_set_expr_location (new_base, loc);
1901 /* Recurse to possibly find the match. */
1902 ret = maybe_fold_offset_to_array_ref (loc, new_base, t, orig_type,
1903 f == TYPE_FIELDS (record_type));
1906 ret = maybe_fold_offset_to_component_ref (loc, field_type, new_base, t,
1912 if (!tail_array_field)
1915 f = tail_array_field;
1916 field_type = TREE_TYPE (f);
1917 offset = int_const_binop (MINUS_EXPR, offset, byte_position (f), 1);
1919 /* If we get here, we've got an aggregate field, and a possibly
1920 nonzero offset into them. Recurse and hope for a valid match. */
1923 base = build1 (INDIRECT_REF, record_type, base);
1924 SET_EXPR_LOCATION (base, loc);
1926 base = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE);
1927 SET_EXPR_LOCATION (base, loc);
1929 t = maybe_fold_offset_to_array_ref (loc, base, offset, orig_type,
1930 f == TYPE_FIELDS (record_type));
1933 return maybe_fold_offset_to_component_ref (loc, field_type, base, offset,
1937 /* Attempt to express (ORIG_TYPE)BASE+OFFSET as BASE->field_of_orig_type
1938 or BASE[index] or by combination of those.
1940 LOC is the location of original expression.
1942 Before attempting the conversion strip off existing ADDR_EXPRs and
1943 handled component refs. */
1946 maybe_fold_offset_to_reference (location_t loc, tree base, tree offset,
1951 bool base_is_ptr = true;
1954 if (TREE_CODE (base) == ADDR_EXPR)
1956 base_is_ptr = false;
1958 base = TREE_OPERAND (base, 0);
1960 /* Handle case where existing COMPONENT_REF pick e.g. wrong field of union,
1961 so it needs to be removed and new COMPONENT_REF constructed.
1962 The wrong COMPONENT_REF are often constructed by folding the
1963 (type *)&object within the expression (type *)&object+offset */
1964 if (handled_component_p (base))
1966 HOST_WIDE_INT sub_offset, size, maxsize;
1968 newbase = get_ref_base_and_extent (base, &sub_offset,
1970 gcc_assert (newbase);
1973 && !(sub_offset & (BITS_PER_UNIT - 1)))
1977 offset = int_const_binop (PLUS_EXPR, offset,
1978 build_int_cst (TREE_TYPE (offset),
1979 sub_offset / BITS_PER_UNIT), 1);
1982 if (useless_type_conversion_p (orig_type, TREE_TYPE (base))
1983 && integer_zerop (offset))
1985 type = TREE_TYPE (base);
1990 if (!POINTER_TYPE_P (TREE_TYPE (base)))
1992 type = TREE_TYPE (TREE_TYPE (base));
1994 ret = maybe_fold_offset_to_component_ref (loc, type, base, offset,
1995 orig_type, base_is_ptr);
2000 base = build1 (INDIRECT_REF, type, base);
2001 SET_EXPR_LOCATION (base, loc);
2003 ret = maybe_fold_offset_to_array_ref (loc,
2004 base, offset, orig_type, true);
2009 /* Attempt to express (ORIG_TYPE)&BASE+OFFSET as &BASE->field_of_orig_type
2010 or &BASE[index] or by combination of those.
2012 LOC is the location of the original expression.
2014 Before attempting the conversion strip off existing component refs. */
2017 maybe_fold_offset_to_address (location_t loc, tree addr, tree offset,
2022 gcc_assert (POINTER_TYPE_P (TREE_TYPE (addr))
2023 && POINTER_TYPE_P (orig_type));
2025 t = maybe_fold_offset_to_reference (loc, addr, offset,
2026 TREE_TYPE (orig_type));
2032 /* For __builtin_object_size to function correctly we need to
2033 make sure not to fold address arithmetic so that we change
2034 reference from one array to another. This would happen for
2037 struct X { char s1[10]; char s2[10] } s;
2038 char *foo (void) { return &s.s2[-4]; }
2040 where we need to avoid generating &s.s1[6]. As the C and
2041 C++ frontends create different initial trees
2042 (char *) &s.s1 + -4 vs. &s.s1[-4] we have to do some
2043 sophisticated comparisons here. Note that checking for the
2044 condition after the fact is easier than trying to avoid doing
2047 if (TREE_CODE (orig) == ADDR_EXPR)
2048 orig = TREE_OPERAND (orig, 0);
2049 if ((TREE_CODE (orig) == ARRAY_REF
2050 || (TREE_CODE (orig) == COMPONENT_REF
2051 && TREE_CODE (TREE_TYPE (TREE_OPERAND (orig, 1))) == ARRAY_TYPE))
2052 && (TREE_CODE (t) == ARRAY_REF
2053 || TREE_CODE (t) == COMPONENT_REF)
2054 && !operand_equal_p (TREE_CODE (orig) == ARRAY_REF
2055 ? TREE_OPERAND (orig, 0) : orig,
2056 TREE_CODE (t) == ARRAY_REF
2057 ? TREE_OPERAND (t, 0) : t, 0))
2060 ptr_type = build_pointer_type (TREE_TYPE (t));
2061 if (!useless_type_conversion_p (orig_type, ptr_type))
2063 return build_fold_addr_expr_with_type_loc (loc, t, ptr_type);
2069 /* A subroutine of fold_stmt. Attempt to simplify *(BASE+OFFSET).
2070 Return the simplified expression, or NULL if nothing could be done. */
2073 maybe_fold_stmt_indirect (tree expr, tree base, tree offset)
2076 bool volatile_p = TREE_THIS_VOLATILE (expr);
2077 location_t loc = EXPR_LOCATION (expr);
2079 /* We may well have constructed a double-nested PLUS_EXPR via multiple
2080 substitutions. Fold that down to one. Remove NON_LVALUE_EXPRs that
2081 are sometimes added. */
2083 STRIP_TYPE_NOPS (base);
2084 TREE_OPERAND (expr, 0) = base;
2086 /* One possibility is that the address reduces to a string constant. */
2087 t = fold_read_from_constant_string (expr);
2091 /* Add in any offset from a POINTER_PLUS_EXPR. */
2092 if (TREE_CODE (base) == POINTER_PLUS_EXPR)
2096 offset2 = TREE_OPERAND (base, 1);
2097 if (TREE_CODE (offset2) != INTEGER_CST)
2099 base = TREE_OPERAND (base, 0);
2101 offset = fold_convert (sizetype,
2102 int_const_binop (PLUS_EXPR, offset, offset2, 1));
2105 if (TREE_CODE (base) == ADDR_EXPR)
2107 tree base_addr = base;
2109 /* Strip the ADDR_EXPR. */
2110 base = TREE_OPERAND (base, 0);
2112 /* Fold away CONST_DECL to its value, if the type is scalar. */
2113 if (TREE_CODE (base) == CONST_DECL
2114 && is_gimple_min_invariant (DECL_INITIAL (base)))
2115 return DECL_INITIAL (base);
2117 /* Try folding *(&B+O) to B.X. */
2118 t = maybe_fold_offset_to_reference (loc, base_addr, offset,
2122 /* Preserve volatileness of the original expression.
2123 We can end up with a plain decl here which is shared
2124 and we shouldn't mess with its flags. */
2126 TREE_THIS_VOLATILE (t) = volatile_p;
2132 /* We can get here for out-of-range string constant accesses,
2133 such as "_"[3]. Bail out of the entire substitution search
2134 and arrange for the entire statement to be replaced by a
2135 call to __builtin_trap. In all likelihood this will all be
2136 constant-folded away, but in the meantime we can't leave with
2137 something that get_expr_operands can't understand. */
2141 if (TREE_CODE (t) == ADDR_EXPR
2142 && TREE_CODE (TREE_OPERAND (t, 0)) == STRING_CST)
2144 /* FIXME: Except that this causes problems elsewhere with dead
2145 code not being deleted, and we die in the rtl expanders
2146 because we failed to remove some ssa_name. In the meantime,
2147 just return zero. */
2148 /* FIXME2: This condition should be signaled by
2149 fold_read_from_constant_string directly, rather than
2150 re-checking for it here. */
2151 return integer_zero_node;
2154 /* Try folding *(B+O) to B->X. Still an improvement. */
2155 if (POINTER_TYPE_P (TREE_TYPE (base)))
2157 t = maybe_fold_offset_to_reference (loc, base, offset,
2164 /* Otherwise we had an offset that we could not simplify. */
2169 /* A quaint feature extant in our address arithmetic is that there
2170 can be hidden type changes here. The type of the result need
2171 not be the same as the type of the input pointer.
2173 What we're after here is an expression of the form
2174 (T *)(&array + const)
2175 where array is OP0, const is OP1, RES_TYPE is T and
2176 the cast doesn't actually exist, but is implicit in the
2177 type of the POINTER_PLUS_EXPR. We'd like to turn this into
2179 which may be able to propagate further. */
2182 maybe_fold_stmt_addition (location_t loc, tree res_type, tree op0, tree op1)
2187 /* The first operand should be an ADDR_EXPR. */
2188 if (TREE_CODE (op0) != ADDR_EXPR)
2190 op0 = TREE_OPERAND (op0, 0);
2192 /* It had better be a constant. */
2193 if (TREE_CODE (op1) != INTEGER_CST)
2195 /* Or op0 should now be A[0] and the non-constant offset defined
2196 via a multiplication by the array element size. */
2197 if (TREE_CODE (op0) == ARRAY_REF
2198 && integer_zerop (TREE_OPERAND (op0, 1))
2199 && TREE_CODE (op1) == SSA_NAME
2200 && host_integerp (TYPE_SIZE_UNIT (TREE_TYPE (op0)), 1))
2202 gimple offset_def = SSA_NAME_DEF_STMT (op1);
2203 if (!is_gimple_assign (offset_def))
2206 if (gimple_assign_rhs_code (offset_def) == MULT_EXPR
2207 && TREE_CODE (gimple_assign_rhs2 (offset_def)) == INTEGER_CST
2208 && tree_int_cst_equal (gimple_assign_rhs2 (offset_def),
2209 TYPE_SIZE_UNIT (TREE_TYPE (op0))))
2210 return build1 (ADDR_EXPR, res_type,
2211 build4 (ARRAY_REF, TREE_TYPE (op0),
2212 TREE_OPERAND (op0, 0),
2213 gimple_assign_rhs1 (offset_def),
2214 TREE_OPERAND (op0, 2),
2215 TREE_OPERAND (op0, 3)));
2216 else if (integer_onep (TYPE_SIZE_UNIT (TREE_TYPE (op0)))
2217 && gimple_assign_rhs_code (offset_def) != MULT_EXPR)
2218 return build1 (ADDR_EXPR, res_type,
2219 build4 (ARRAY_REF, TREE_TYPE (op0),
2220 TREE_OPERAND (op0, 0),
2222 TREE_OPERAND (op0, 2),
2223 TREE_OPERAND (op0, 3)));
2228 /* If the first operand is an ARRAY_REF, expand it so that we can fold
2229 the offset into it. */
2230 while (TREE_CODE (op0) == ARRAY_REF)
2232 tree array_obj = TREE_OPERAND (op0, 0);
2233 tree array_idx = TREE_OPERAND (op0, 1);
2234 tree elt_type = TREE_TYPE (op0);
2235 tree elt_size = TYPE_SIZE_UNIT (elt_type);
2238 if (TREE_CODE (array_idx) != INTEGER_CST)
2240 if (TREE_CODE (elt_size) != INTEGER_CST)
2243 /* Un-bias the index by the min index of the array type. */
2244 min_idx = TYPE_DOMAIN (TREE_TYPE (array_obj));
2247 min_idx = TYPE_MIN_VALUE (min_idx);
2250 if (TREE_CODE (min_idx) != INTEGER_CST)
2253 array_idx = fold_convert (TREE_TYPE (min_idx), array_idx);
2254 if (!integer_zerop (min_idx))
2255 array_idx = int_const_binop (MINUS_EXPR, array_idx,
2260 /* Convert the index to a byte offset. */
2261 array_idx = fold_convert (sizetype, array_idx);
2262 array_idx = int_const_binop (MULT_EXPR, array_idx, elt_size, 0);
2264 /* Update the operands for the next round, or for folding. */
2265 op1 = int_const_binop (PLUS_EXPR,
2270 ptd_type = TREE_TYPE (res_type);
2271 /* If we want a pointer to void, reconstruct the reference from the
2272 array element type. A pointer to that can be trivially converted
2273 to void *. This happens as we fold (void *)(ptr p+ off). */
2274 if (VOID_TYPE_P (ptd_type)
2275 && TREE_CODE (TREE_TYPE (op0)) == ARRAY_TYPE)
2276 ptd_type = TREE_TYPE (TREE_TYPE (op0));
2278 /* At which point we can try some of the same things as for indirects. */
2279 t = maybe_fold_offset_to_array_ref (loc, op0, op1, ptd_type, true);
2281 t = maybe_fold_offset_to_component_ref (loc, TREE_TYPE (op0), op0, op1,
2285 t = build1 (ADDR_EXPR, res_type, t);
2286 SET_EXPR_LOCATION (t, loc);
2292 /* Subroutine of fold_stmt. We perform several simplifications of the
2293 memory reference tree EXPR and make sure to re-gimplify them properly
2294 after propagation of constant addresses. IS_LHS is true if the
2295 reference is supposed to be an lvalue. */
2298 maybe_fold_reference (tree expr, bool is_lhs)
2302 if (TREE_CODE (expr) == ARRAY_REF
2305 tree tem = fold_read_from_constant_string (expr);
2310 /* ??? We might want to open-code the relevant remaining cases
2311 to avoid using the generic fold. */
2312 if (handled_component_p (*t)
2313 && CONSTANT_CLASS_P (TREE_OPERAND (*t, 0)))
2315 tree tem = fold (*t);
2320 while (handled_component_p (*t))
2321 t = &TREE_OPERAND (*t, 0);
2323 if (TREE_CODE (*t) == INDIRECT_REF)
2325 tree tem = maybe_fold_stmt_indirect (*t, TREE_OPERAND (*t, 0),
2327 /* Avoid folding *"abc" = 5 into 'a' = 5. */
2328 if (is_lhs && tem && CONSTANT_CLASS_P (tem))
2331 && TREE_CODE (TREE_OPERAND (*t, 0)) == ADDR_EXPR)
2332 /* If we had a good reason for propagating the address here,
2333 make sure we end up with valid gimple. See PR34989. */
2334 tem = TREE_OPERAND (TREE_OPERAND (*t, 0), 0);
2339 tem = maybe_fold_reference (expr, is_lhs);
2348 tree tem = get_symbol_constant_value (*t);
2352 tem = maybe_fold_reference (expr, is_lhs);
2363 /* Return the string length, maximum string length or maximum value of
2365 If ARG is an SSA name variable, follow its use-def chains. If LENGTH
2366 is not NULL and, for TYPE == 0, its value is not equal to the length
2367 we determine or if we are unable to determine the length or value,
2368 return false. VISITED is a bitmap of visited variables.
2369 TYPE is 0 if string length should be returned, 1 for maximum string
2370 length and 2 for maximum value ARG can have. */
2373 get_maxval_strlen (tree arg, tree *length, bitmap visited, int type)
2378 if (TREE_CODE (arg) != SSA_NAME)
2380 if (TREE_CODE (arg) == COND_EXPR)
2381 return get_maxval_strlen (COND_EXPR_THEN (arg), length, visited, type)
2382 && get_maxval_strlen (COND_EXPR_ELSE (arg), length, visited, type);
2383 /* We can end up with &(*iftmp_1)[0] here as well, so handle it. */
2384 else if (TREE_CODE (arg) == ADDR_EXPR
2385 && TREE_CODE (TREE_OPERAND (arg, 0)) == ARRAY_REF
2386 && integer_zerop (TREE_OPERAND (TREE_OPERAND (arg, 0), 1)))
2388 tree aop0 = TREE_OPERAND (TREE_OPERAND (arg, 0), 0);
2389 if (TREE_CODE (aop0) == INDIRECT_REF
2390 && TREE_CODE (TREE_OPERAND (aop0, 0)) == SSA_NAME)
2391 return get_maxval_strlen (TREE_OPERAND (aop0, 0),
2392 length, visited, type);
2398 if (TREE_CODE (val) != INTEGER_CST
2399 || tree_int_cst_sgn (val) < 0)
2403 val = c_strlen (arg, 1);
2411 if (TREE_CODE (*length) != INTEGER_CST
2412 || TREE_CODE (val) != INTEGER_CST)
2415 if (tree_int_cst_lt (*length, val))
2419 else if (simple_cst_equal (val, *length) != 1)
2427 /* If we were already here, break the infinite cycle. */
2428 if (bitmap_bit_p (visited, SSA_NAME_VERSION (arg)))
2430 bitmap_set_bit (visited, SSA_NAME_VERSION (arg));
2433 def_stmt = SSA_NAME_DEF_STMT (var);
2435 switch (gimple_code (def_stmt))
2438 /* The RHS of the statement defining VAR must either have a
2439 constant length or come from another SSA_NAME with a constant
2441 if (gimple_assign_single_p (def_stmt)
2442 || gimple_assign_unary_nop_p (def_stmt))
2444 tree rhs = gimple_assign_rhs1 (def_stmt);
2445 return get_maxval_strlen (rhs, length, visited, type);
2451 /* All the arguments of the PHI node must have the same constant
2455 for (i = 0; i < gimple_phi_num_args (def_stmt); i++)
2457 tree arg = gimple_phi_arg (def_stmt, i)->def;
2459 /* If this PHI has itself as an argument, we cannot
2460 determine the string length of this argument. However,
2461 if we can find a constant string length for the other
2462 PHI args then we can still be sure that this is a
2463 constant string length. So be optimistic and just
2464 continue with the next argument. */
2465 if (arg == gimple_phi_result (def_stmt))
2468 if (!get_maxval_strlen (arg, length, visited, type))
2480 /* Fold builtin call in statement STMT. Returns a simplified tree.
2481 We may return a non-constant expression, including another call
2482 to a different function and with different arguments, e.g.,
2483 substituting memcpy for strcpy when the string length is known.
2484 Note that some builtins expand into inline code that may not
2485 be valid in GIMPLE. Callers must take care. */
2488 ccp_fold_builtin (gimple stmt)
2490 tree result, val[3];
2496 location_t loc = gimple_location (stmt);
2498 gcc_assert (is_gimple_call (stmt));
2500 ignore = (gimple_call_lhs (stmt) == NULL);
2502 /* First try the generic builtin folder. If that succeeds, return the
2504 result = fold_call_stmt (stmt, ignore);
2508 STRIP_NOPS (result);
2512 /* Ignore MD builtins. */
2513 callee = gimple_call_fndecl (stmt);
2514 if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_MD)
2517 /* If the builtin could not be folded, and it has no argument list,
2519 nargs = gimple_call_num_args (stmt);
2523 /* Limit the work only for builtins we know how to simplify. */
2524 switch (DECL_FUNCTION_CODE (callee))
2526 case BUILT_IN_STRLEN:
2527 case BUILT_IN_FPUTS:
2528 case BUILT_IN_FPUTS_UNLOCKED:
2532 case BUILT_IN_STRCPY:
2533 case BUILT_IN_STRNCPY:
2537 case BUILT_IN_MEMCPY_CHK:
2538 case BUILT_IN_MEMPCPY_CHK:
2539 case BUILT_IN_MEMMOVE_CHK:
2540 case BUILT_IN_MEMSET_CHK:
2541 case BUILT_IN_STRNCPY_CHK:
2545 case BUILT_IN_STRCPY_CHK:
2546 case BUILT_IN_STPCPY_CHK:
2550 case BUILT_IN_SNPRINTF_CHK:
2551 case BUILT_IN_VSNPRINTF_CHK:
2559 if (arg_idx >= nargs)
2562 /* Try to use the dataflow information gathered by the CCP process. */
2563 visited = BITMAP_ALLOC (NULL);
2564 bitmap_clear (visited);
2566 memset (val, 0, sizeof (val));
2567 a = gimple_call_arg (stmt, arg_idx);
2568 if (!get_maxval_strlen (a, &val[arg_idx], visited, type))
2569 val[arg_idx] = NULL_TREE;
2571 BITMAP_FREE (visited);
2574 switch (DECL_FUNCTION_CODE (callee))
2576 case BUILT_IN_STRLEN:
2577 if (val[0] && nargs == 1)
2580 fold_convert (TREE_TYPE (gimple_call_lhs (stmt)), val[0]);
2582 /* If the result is not a valid gimple value, or not a cast
2583 of a valid gimple value, then we can not use the result. */
2584 if (is_gimple_val (new_val)
2585 || (is_gimple_cast (new_val)
2586 && is_gimple_val (TREE_OPERAND (new_val, 0))))
2591 case BUILT_IN_STRCPY:
2592 if (val[1] && is_gimple_val (val[1]) && nargs == 2)
2593 result = fold_builtin_strcpy (loc, callee,
2594 gimple_call_arg (stmt, 0),
2595 gimple_call_arg (stmt, 1),
2599 case BUILT_IN_STRNCPY:
2600 if (val[1] && is_gimple_val (val[1]) && nargs == 3)
2601 result = fold_builtin_strncpy (loc, callee,
2602 gimple_call_arg (stmt, 0),
2603 gimple_call_arg (stmt, 1),
2604 gimple_call_arg (stmt, 2),
2608 case BUILT_IN_FPUTS:
2610 result = fold_builtin_fputs (loc, gimple_call_arg (stmt, 0),
2611 gimple_call_arg (stmt, 1),
2612 ignore, false, val[0]);
2615 case BUILT_IN_FPUTS_UNLOCKED:
2617 result = fold_builtin_fputs (loc, gimple_call_arg (stmt, 0),
2618 gimple_call_arg (stmt, 1),
2619 ignore, true, val[0]);
2622 case BUILT_IN_MEMCPY_CHK:
2623 case BUILT_IN_MEMPCPY_CHK:
2624 case BUILT_IN_MEMMOVE_CHK:
2625 case BUILT_IN_MEMSET_CHK:
2626 if (val[2] && is_gimple_val (val[2]) && nargs == 4)
2627 result = fold_builtin_memory_chk (loc, callee,
2628 gimple_call_arg (stmt, 0),
2629 gimple_call_arg (stmt, 1),
2630 gimple_call_arg (stmt, 2),
2631 gimple_call_arg (stmt, 3),
2633 DECL_FUNCTION_CODE (callee));
2636 case BUILT_IN_STRCPY_CHK:
2637 case BUILT_IN_STPCPY_CHK:
2638 if (val[1] && is_gimple_val (val[1]) && nargs == 3)
2639 result = fold_builtin_stxcpy_chk (loc, callee,
2640 gimple_call_arg (stmt, 0),
2641 gimple_call_arg (stmt, 1),
2642 gimple_call_arg (stmt, 2),
2644 DECL_FUNCTION_CODE (callee));
2647 case BUILT_IN_STRNCPY_CHK:
2648 if (val[2] && is_gimple_val (val[2]) && nargs == 4)
2649 result = fold_builtin_strncpy_chk (loc, gimple_call_arg (stmt, 0),
2650 gimple_call_arg (stmt, 1),
2651 gimple_call_arg (stmt, 2),
2652 gimple_call_arg (stmt, 3),
2656 case BUILT_IN_SNPRINTF_CHK:
2657 case BUILT_IN_VSNPRINTF_CHK:
2658 if (val[1] && is_gimple_val (val[1]))
2659 result = gimple_fold_builtin_snprintf_chk (stmt, val[1],
2660 DECL_FUNCTION_CODE (callee));
2667 if (result && ignore)
2668 result = fold_ignored_result (result);
2672 /* Attempt to fold an assignment statement pointed-to by SI. Returns a
2673 replacement rhs for the statement or NULL_TREE if no simplification
2674 could be made. It is assumed that the operands have been previously
2678 fold_gimple_assign (gimple_stmt_iterator *si)
2680 gimple stmt = gsi_stmt (*si);
2681 enum tree_code subcode = gimple_assign_rhs_code (stmt);
2682 location_t loc = gimple_location (stmt);
2684 tree result = NULL_TREE;
2686 switch (get_gimple_rhs_class (subcode))
2688 case GIMPLE_SINGLE_RHS:
2690 tree rhs = gimple_assign_rhs1 (stmt);
2692 /* Try to fold a conditional expression. */
2693 if (TREE_CODE (rhs) == COND_EXPR)
2695 tree op0 = COND_EXPR_COND (rhs);
2698 location_t cond_loc = EXPR_LOCATION (rhs);
2700 if (COMPARISON_CLASS_P (op0))
2702 fold_defer_overflow_warnings ();
2703 tem = fold_binary_loc (cond_loc,
2704 TREE_CODE (op0), TREE_TYPE (op0),
2705 TREE_OPERAND (op0, 0),
2706 TREE_OPERAND (op0, 1));
2707 /* This is actually a conditional expression, not a GIMPLE
2708 conditional statement, however, the valid_gimple_rhs_p
2709 test still applies. */
2710 set = (tem && is_gimple_condexpr (tem)
2711 && valid_gimple_rhs_p (tem));
2712 fold_undefer_overflow_warnings (set, stmt, 0);
2714 else if (is_gimple_min_invariant (op0))
2723 result = fold_build3_loc (cond_loc, COND_EXPR, TREE_TYPE (rhs), tem,
2724 COND_EXPR_THEN (rhs), COND_EXPR_ELSE (rhs));
2727 else if (TREE_CODE (rhs) == TARGET_MEM_REF)
2728 return maybe_fold_tmr (rhs);
2730 else if (REFERENCE_CLASS_P (rhs))
2731 return maybe_fold_reference (rhs, false);
2733 else if (TREE_CODE (rhs) == ADDR_EXPR)
2735 tree tem = maybe_fold_reference (TREE_OPERAND (rhs, 0), true);
2737 result = fold_convert (TREE_TYPE (rhs),
2738 build_fold_addr_expr_loc (loc, tem));
2741 else if (TREE_CODE (rhs) == CONSTRUCTOR
2742 && TREE_CODE (TREE_TYPE (rhs)) == VECTOR_TYPE
2743 && (CONSTRUCTOR_NELTS (rhs)
2744 == TYPE_VECTOR_SUBPARTS (TREE_TYPE (rhs))))
2746 /* Fold a constant vector CONSTRUCTOR to VECTOR_CST. */
2750 FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (rhs), i, val)
2751 if (TREE_CODE (val) != INTEGER_CST
2752 && TREE_CODE (val) != REAL_CST
2753 && TREE_CODE (val) != FIXED_CST)
2756 return build_vector_from_ctor (TREE_TYPE (rhs),
2757 CONSTRUCTOR_ELTS (rhs));
2760 else if (DECL_P (rhs))
2761 return get_symbol_constant_value (rhs);
2763 /* If we couldn't fold the RHS, hand over to the generic
2765 if (result == NULL_TREE)
2766 result = fold (rhs);
2768 /* Strip away useless type conversions. Both the NON_LVALUE_EXPR
2769 that may have been added by fold, and "useless" type
2770 conversions that might now be apparent due to propagation. */
2771 STRIP_USELESS_TYPE_CONVERSION (result);
2773 if (result != rhs && valid_gimple_rhs_p (result))
2780 case GIMPLE_UNARY_RHS:
2782 tree rhs = gimple_assign_rhs1 (stmt);
2784 result = fold_unary_loc (loc, subcode, gimple_expr_type (stmt), rhs);
2787 /* If the operation was a conversion do _not_ mark a
2788 resulting constant with TREE_OVERFLOW if the original
2789 constant was not. These conversions have implementation
2790 defined behavior and retaining the TREE_OVERFLOW flag
2791 here would confuse later passes such as VRP. */
2792 if (CONVERT_EXPR_CODE_P (subcode)
2793 && TREE_CODE (result) == INTEGER_CST
2794 && TREE_CODE (rhs) == INTEGER_CST)
2795 TREE_OVERFLOW (result) = TREE_OVERFLOW (rhs);
2797 STRIP_USELESS_TYPE_CONVERSION (result);
2798 if (valid_gimple_rhs_p (result))
2801 else if (CONVERT_EXPR_CODE_P (subcode)
2802 && POINTER_TYPE_P (gimple_expr_type (stmt))
2803 && POINTER_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (stmt))))
2805 tree type = gimple_expr_type (stmt);
2806 tree t = maybe_fold_offset_to_address (loc,
2807 gimple_assign_rhs1 (stmt),
2808 integer_zero_node, type);
2815 case GIMPLE_BINARY_RHS:
2816 /* Try to fold pointer addition. */
2817 if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR)
2819 tree type = TREE_TYPE (gimple_assign_rhs1 (stmt));
2820 if (TREE_CODE (TREE_TYPE (type)) == ARRAY_TYPE)
2822 type = build_pointer_type (TREE_TYPE (TREE_TYPE (type)));
2823 if (!useless_type_conversion_p
2824 (TREE_TYPE (gimple_assign_lhs (stmt)), type))
2825 type = TREE_TYPE (gimple_assign_rhs1 (stmt));
2827 result = maybe_fold_stmt_addition (gimple_location (stmt),
2829 gimple_assign_rhs1 (stmt),
2830 gimple_assign_rhs2 (stmt));
2834 result = fold_binary_loc (loc, subcode,
2835 TREE_TYPE (gimple_assign_lhs (stmt)),
2836 gimple_assign_rhs1 (stmt),
2837 gimple_assign_rhs2 (stmt));
2841 STRIP_USELESS_TYPE_CONVERSION (result);
2842 if (valid_gimple_rhs_p (result))
2845 /* Fold might have produced non-GIMPLE, so if we trust it blindly
2846 we lose canonicalization opportunities. Do not go again
2847 through fold here though, or the same non-GIMPLE will be
2849 if (commutative_tree_code (subcode)
2850 && tree_swap_operands_p (gimple_assign_rhs1 (stmt),
2851 gimple_assign_rhs2 (stmt), false))
2852 return build2 (subcode, TREE_TYPE (gimple_assign_lhs (stmt)),
2853 gimple_assign_rhs2 (stmt),
2854 gimple_assign_rhs1 (stmt));
2858 case GIMPLE_INVALID_RHS:
2865 /* Attempt to fold a conditional statement. Return true if any changes were
2866 made. We only attempt to fold the condition expression, and do not perform
2867 any transformation that would require alteration of the cfg. It is
2868 assumed that the operands have been previously folded. */
2871 fold_gimple_cond (gimple stmt)
2873 tree result = fold_binary_loc (gimple_location (stmt),
2874 gimple_cond_code (stmt),
2876 gimple_cond_lhs (stmt),
2877 gimple_cond_rhs (stmt));
2881 STRIP_USELESS_TYPE_CONVERSION (result);
2882 if (is_gimple_condexpr (result) && valid_gimple_rhs_p (result))
2884 gimple_cond_set_condition_from_tree (stmt, result);
2893 /* Attempt to fold a call statement referenced by the statement iterator GSI.
2894 The statement may be replaced by another statement, e.g., if the call
2895 simplifies to a constant value. Return true if any changes were made.
2896 It is assumed that the operands have been previously folded. */
2899 fold_gimple_call (gimple_stmt_iterator *gsi)
2901 gimple stmt = gsi_stmt (*gsi);
2903 tree callee = gimple_call_fndecl (stmt);
2905 /* Check for builtins that CCP can handle using information not
2906 available in the generic fold routines. */
2907 if (callee && DECL_BUILT_IN (callee))
2909 tree result = ccp_fold_builtin (stmt);
2912 return update_call_from_tree (gsi, result);
2916 /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve
2917 here are when we've propagated the address of a decl into the
2919 /* ??? Should perhaps do this in fold proper. However, doing it
2920 there requires that we create a new CALL_EXPR, and that requires
2921 copying EH region info to the new node. Easier to just do it
2922 here where we can just smash the call operand. */
2923 /* ??? Is there a good reason not to do this in fold_stmt_inplace? */
2924 callee = gimple_call_fn (stmt);
2925 if (TREE_CODE (callee) == OBJ_TYPE_REF
2926 && lang_hooks.fold_obj_type_ref
2927 && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee)) == ADDR_EXPR
2928 && DECL_P (TREE_OPERAND
2929 (OBJ_TYPE_REF_OBJECT (callee), 0)))
2933 /* ??? Caution: Broken ADDR_EXPR semantics means that
2934 looking at the type of the operand of the addr_expr
2935 can yield an array type. See silly exception in
2936 check_pointer_types_r. */
2937 t = TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee)));
2938 t = lang_hooks.fold_obj_type_ref (callee, t);
2941 gimple_call_set_fn (stmt, t);
2950 /* Worker for both fold_stmt and fold_stmt_inplace. The INPLACE argument
2951 distinguishes both cases. */
2954 fold_stmt_1 (gimple_stmt_iterator *gsi, bool inplace)
2956 bool changed = false;
2957 gimple stmt = gsi_stmt (*gsi);
2960 /* Fold the main computation performed by the statement. */
2961 switch (gimple_code (stmt))
2965 unsigned old_num_ops = gimple_num_ops (stmt);
2966 tree new_rhs = fold_gimple_assign (gsi);
2967 if (new_rhs != NULL_TREE
2969 || get_gimple_rhs_num_ops (TREE_CODE (new_rhs)) < old_num_ops))
2971 gimple_assign_set_rhs_from_tree (gsi, new_rhs);
2978 changed |= fold_gimple_cond (stmt);
2982 /* Fold *& in call arguments. */
2983 for (i = 0; i < gimple_call_num_args (stmt); ++i)
2984 if (REFERENCE_CLASS_P (gimple_call_arg (stmt, i)))
2986 tree tmp = maybe_fold_reference (gimple_call_arg (stmt, i), false);
2989 gimple_call_set_arg (stmt, i, tmp);
2993 /* The entire statement may be replaced in this case. */
2995 changed |= fold_gimple_call (gsi);
2999 /* Fold *& in asm operands. */
3000 for (i = 0; i < gimple_asm_noutputs (stmt); ++i)
3002 tree link = gimple_asm_output_op (stmt, i);
3003 tree op = TREE_VALUE (link);
3004 if (REFERENCE_CLASS_P (op)
3005 && (op = maybe_fold_reference (op, true)) != NULL_TREE)
3007 TREE_VALUE (link) = op;
3011 for (i = 0; i < gimple_asm_ninputs (stmt); ++i)
3013 tree link = gimple_asm_input_op (stmt, i);
3014 tree op = TREE_VALUE (link);
3015 if (REFERENCE_CLASS_P (op)
3016 && (op = maybe_fold_reference (op, false)) != NULL_TREE)
3018 TREE_VALUE (link) = op;
3027 stmt = gsi_stmt (*gsi);
3029 /* Fold *& on the lhs. */
3030 if (gimple_has_lhs (stmt))
3032 tree lhs = gimple_get_lhs (stmt);
3033 if (lhs && REFERENCE_CLASS_P (lhs))
3035 tree new_lhs = maybe_fold_reference (lhs, true);
3038 gimple_set_lhs (stmt, new_lhs);
3047 /* Fold the statement pointed to by GSI. In some cases, this function may
3048 replace the whole statement with a new one. Returns true iff folding
3050 The statement pointed to by GSI should be in valid gimple form but may
3051 be in unfolded state as resulting from for example constant propagation
3052 which can produce *&x = 0. */
3055 fold_stmt (gimple_stmt_iterator *gsi)
3057 return fold_stmt_1 (gsi, false);
3060 /* Perform the minimal folding on statement STMT. Only operations like
3061 *&x created by constant propagation are handled. The statement cannot
3062 be replaced with a new one. Return true if the statement was
3063 changed, false otherwise.
3064 The statement STMT should be in valid gimple form but may
3065 be in unfolded state as resulting from for example constant propagation
3066 which can produce *&x = 0. */
3069 fold_stmt_inplace (gimple stmt)
3071 gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
3072 bool changed = fold_stmt_1 (&gsi, true);
3073 gcc_assert (gsi_stmt (gsi) == stmt);
3077 /* Try to optimize out __builtin_stack_restore. Optimize it out
3078 if there is another __builtin_stack_restore in the same basic
3079 block and no calls or ASM_EXPRs are in between, or if this block's
3080 only outgoing edge is to EXIT_BLOCK and there are no calls or
3081 ASM_EXPRs after this __builtin_stack_restore. */
3084 optimize_stack_restore (gimple_stmt_iterator i)
3087 gimple stmt, stack_save;
3088 gimple_stmt_iterator stack_save_gsi;
3090 basic_block bb = gsi_bb (i);
3091 gimple call = gsi_stmt (i);
3093 if (gimple_code (call) != GIMPLE_CALL
3094 || gimple_call_num_args (call) != 1
3095 || TREE_CODE (gimple_call_arg (call, 0)) != SSA_NAME
3096 || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call, 0))))
3099 for (gsi_next (&i); !gsi_end_p (i); gsi_next (&i))
3101 stmt = gsi_stmt (i);
3102 if (gimple_code (stmt) == GIMPLE_ASM)
3104 if (gimple_code (stmt) != GIMPLE_CALL)
3107 callee = gimple_call_fndecl (stmt);
3108 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
3111 if (DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_RESTORE)
3116 && (! single_succ_p (bb)
3117 || single_succ_edge (bb)->dest != EXIT_BLOCK_PTR))
3120 stack_save = SSA_NAME_DEF_STMT (gimple_call_arg (call, 0));
3121 if (gimple_code (stack_save) != GIMPLE_CALL
3122 || gimple_call_lhs (stack_save) != gimple_call_arg (call, 0)
3123 || stmt_could_throw_p (stack_save)
3124 || !has_single_use (gimple_call_arg (call, 0)))
3127 callee = gimple_call_fndecl (stack_save);
3129 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
3130 || DECL_FUNCTION_CODE (callee) != BUILT_IN_STACK_SAVE
3131 || gimple_call_num_args (stack_save) != 0)
3134 stack_save_gsi = gsi_for_stmt (stack_save);
3135 rhs = build_int_cst (TREE_TYPE (gimple_call_arg (call, 0)), 0);
3136 if (!update_call_from_tree (&stack_save_gsi, rhs))
3139 /* No effect, so the statement will be deleted. */
3140 return integer_zero_node;
3143 /* If va_list type is a simple pointer and nothing special is needed,
3144 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
3145 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
3146 pointer assignment. */
3149 optimize_stdarg_builtin (gimple call)
3151 tree callee, lhs, rhs, cfun_va_list;
3152 bool va_list_simple_ptr;
3153 location_t loc = gimple_location (call);
3155 if (gimple_code (call) != GIMPLE_CALL)
3158 callee = gimple_call_fndecl (call);
3160 cfun_va_list = targetm.fn_abi_va_list (callee);
3161 va_list_simple_ptr = POINTER_TYPE_P (cfun_va_list)
3162 && (TREE_TYPE (cfun_va_list) == void_type_node
3163 || TREE_TYPE (cfun_va_list) == char_type_node);
3165 switch (DECL_FUNCTION_CODE (callee))
3167 case BUILT_IN_VA_START:
3168 if (!va_list_simple_ptr
3169 || targetm.expand_builtin_va_start != NULL
3170 || built_in_decls[BUILT_IN_NEXT_ARG] == NULL)
3173 if (gimple_call_num_args (call) != 2)
3176 lhs = gimple_call_arg (call, 0);
3177 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
3178 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
3179 != TYPE_MAIN_VARIANT (cfun_va_list))
3182 lhs = build_fold_indirect_ref_loc (loc, lhs);
3183 rhs = build_call_expr_loc (loc, built_in_decls[BUILT_IN_NEXT_ARG],
3184 1, integer_zero_node);
3185 rhs = fold_convert_loc (loc, TREE_TYPE (lhs), rhs);
3186 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
3188 case BUILT_IN_VA_COPY:
3189 if (!va_list_simple_ptr)
3192 if (gimple_call_num_args (call) != 2)
3195 lhs = gimple_call_arg (call, 0);
3196 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
3197 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
3198 != TYPE_MAIN_VARIANT (cfun_va_list))
3201 lhs = build_fold_indirect_ref_loc (loc, lhs);
3202 rhs = gimple_call_arg (call, 1);
3203 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs))
3204 != TYPE_MAIN_VARIANT (cfun_va_list))
3207 rhs = fold_convert_loc (loc, TREE_TYPE (lhs), rhs);
3208 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
3210 case BUILT_IN_VA_END:
3211 /* No effect, so the statement will be deleted. */
3212 return integer_zero_node;
3219 /* Convert EXPR into a GIMPLE value suitable for substitution on the
3220 RHS of an assignment. Insert the necessary statements before
3221 iterator *SI_P. The statement at *SI_P, which must be a GIMPLE_CALL
3222 is replaced. If the call is expected to produces a result, then it
3223 is replaced by an assignment of the new RHS to the result variable.
3224 If the result is to be ignored, then the call is replaced by a
3228 gimplify_and_update_call_from_tree (gimple_stmt_iterator *si_p, tree expr)
3231 tree tmp = NULL_TREE; /* Silence warning. */
3232 gimple stmt, new_stmt;
3233 gimple_stmt_iterator i;
3234 gimple_seq stmts = gimple_seq_alloc();
3235 struct gimplify_ctx gctx;
3237 stmt = gsi_stmt (*si_p);
3239 gcc_assert (is_gimple_call (stmt));
3241 lhs = gimple_call_lhs (stmt);
3243 push_gimplify_context (&gctx);
3245 if (lhs == NULL_TREE)
3246 gimplify_and_add (expr, &stmts);
3248 tmp = get_initialized_tmp_var (expr, &stmts, NULL);
3250 pop_gimplify_context (NULL);
3252 if (gimple_has_location (stmt))
3253 annotate_all_with_location (stmts, gimple_location (stmt));
3255 /* The replacement can expose previously unreferenced variables. */
3256 for (i = gsi_start (stmts); !gsi_end_p (i); gsi_next (&i))
3258 new_stmt = gsi_stmt (i);
3259 find_new_referenced_vars (new_stmt);
3260 gsi_insert_before (si_p, new_stmt, GSI_NEW_STMT);
3261 mark_symbols_for_renaming (new_stmt);
3265 if (lhs == NULL_TREE)
3267 new_stmt = gimple_build_nop ();
3268 unlink_stmt_vdef (stmt);
3269 release_defs (stmt);
3273 new_stmt = gimple_build_assign (lhs, tmp);
3274 gimple_set_vuse (new_stmt, gimple_vuse (stmt));
3275 gimple_set_vdef (new_stmt, gimple_vdef (stmt));
3276 move_ssa_defining_stmt_for_defs (new_stmt, stmt);
3279 gimple_set_location (new_stmt, gimple_location (stmt));
3280 gsi_replace (si_p, new_stmt, false);
3283 /* A simple pass that attempts to fold all builtin functions. This pass
3284 is run after we've propagated as many constants as we can. */
3287 execute_fold_all_builtins (void)
3289 bool cfg_changed = false;
3291 unsigned int todoflags = 0;
3295 gimple_stmt_iterator i;
3296 for (i = gsi_start_bb (bb); !gsi_end_p (i); )
3298 gimple stmt, old_stmt;
3299 tree callee, result;
3300 enum built_in_function fcode;
3302 stmt = gsi_stmt (i);
3304 if (gimple_code (stmt) != GIMPLE_CALL)
3309 callee = gimple_call_fndecl (stmt);
3310 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
3315 fcode = DECL_FUNCTION_CODE (callee);
3317 result = ccp_fold_builtin (stmt);
3320 gimple_remove_stmt_histograms (cfun, stmt);
3323 switch (DECL_FUNCTION_CODE (callee))
3325 case BUILT_IN_CONSTANT_P:
3326 /* Resolve __builtin_constant_p. If it hasn't been
3327 folded to integer_one_node by now, it's fairly
3328 certain that the value simply isn't constant. */
3329 result = integer_zero_node;
3332 case BUILT_IN_STACK_RESTORE:
3333 result = optimize_stack_restore (i);
3339 case BUILT_IN_VA_START:
3340 case BUILT_IN_VA_END:
3341 case BUILT_IN_VA_COPY:
3342 /* These shouldn't be folded before pass_stdarg. */
3343 result = optimize_stdarg_builtin (stmt);
3353 if (dump_file && (dump_flags & TDF_DETAILS))
3355 fprintf (dump_file, "Simplified\n ");
3356 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
3360 if (!update_call_from_tree (&i, result))
3362 gimplify_and_update_call_from_tree (&i, result);
3363 todoflags |= TODO_update_address_taken;
3366 stmt = gsi_stmt (i);
3369 if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt)
3370 && gimple_purge_dead_eh_edges (bb))
3373 if (dump_file && (dump_flags & TDF_DETAILS))
3375 fprintf (dump_file, "to\n ");
3376 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
3377 fprintf (dump_file, "\n");
3380 /* Retry the same statement if it changed into another
3381 builtin, there might be new opportunities now. */
3382 if (gimple_code (stmt) != GIMPLE_CALL)
3387 callee = gimple_call_fndecl (stmt);
3389 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
3390 || DECL_FUNCTION_CODE (callee) == fcode)
3395 /* Delete unreachable blocks. */
3397 todoflags |= TODO_cleanup_cfg;
3403 struct gimple_opt_pass pass_fold_builtins =
3409 execute_fold_all_builtins, /* execute */
3412 0, /* static_pass_number */
3413 TV_NONE, /* tv_id */
3414 PROP_cfg | PROP_ssa, /* properties_required */
3415 0, /* properties_provided */
3416 0, /* properties_destroyed */
3417 0, /* todo_flags_start */
3420 | TODO_update_ssa /* todo_flags_finish */