1 /* Conditional constant propagation pass for the GNU compiler.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
3 Free Software Foundation, Inc.
4 Adapted from original RTL SSA-CCP by Daniel Berlin <dberlin@dberlin.org>
5 Adapted to GIMPLE trees by Diego Novillo <dnovillo@redhat.com>
7 This file is part of GCC.
9 GCC is free software; you can redistribute it and/or modify it
10 under the terms of the GNU General Public License as published by the
11 Free Software Foundation; either version 2, or (at your option) any
14 GCC is distributed in the hope that it will be useful, but WITHOUT
15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
16 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
19 You should have received a copy of the GNU General Public License
20 along with GCC; see the file COPYING. If not, write to the Free
21 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
24 /* Conditional constant propagation (CCP) is based on the SSA
25 propagation engine (tree-ssa-propagate.c). Constant assignments of
26 the form VAR = CST are propagated from the assignments into uses of
27 VAR, which in turn may generate new constants. The simulation uses
28 a four level lattice to keep track of constant values associated
29 with SSA names. Given an SSA name V_i, it may take one of the
32 UNINITIALIZED -> the initial state of the value. This value
33 is replaced with a correct initial value
34 the first time the value is used, so the
35 rest of the pass does not need to care about
36 it. Using this value simplifies initialization
37 of the pass, and prevents us from needlessly
38 scanning statements that are never reached.
40 UNDEFINED -> V_i is a local variable whose definition
41 has not been processed yet. Therefore we
42 don't yet know if its value is a constant
45 CONSTANT -> V_i has been found to hold a constant
48 VARYING -> V_i cannot take a constant value, or if it
49 does, it is not possible to determine it
52 The core of SSA-CCP is in ccp_visit_stmt and ccp_visit_phi_node:
54 1- In ccp_visit_stmt, we are interested in assignments whose RHS
55 evaluates into a constant and conditional jumps whose predicate
56 evaluates into a boolean true or false. When an assignment of
57 the form V_i = CONST is found, V_i's lattice value is set to
58 CONSTANT and CONST is associated with it. This causes the
59 propagation engine to add all the SSA edges coming out the
60 assignment into the worklists, so that statements that use V_i
63 If the statement is a conditional with a constant predicate, we
64 mark the outgoing edges as executable or not executable
65 depending on the predicate's value. This is then used when
66 visiting PHI nodes to know when a PHI argument can be ignored.
69 2- In ccp_visit_phi_node, if all the PHI arguments evaluate to the
70 same constant C, then the LHS of the PHI is set to C. This
71 evaluation is known as the "meet operation". Since one of the
72 goals of this evaluation is to optimistically return constant
73 values as often as possible, it uses two main short cuts:
75 - If an argument is flowing in through a non-executable edge, it
76 is ignored. This is useful in cases like this:
82 a_11 = PHI (a_9, a_10)
84 If PRED is known to always evaluate to false, then we can
85 assume that a_11 will always take its value from a_10, meaning
86 that instead of consider it VARYING (a_9 and a_10 have
87 different values), we can consider it CONSTANT 100.
89 - If an argument has an UNDEFINED value, then it does not affect
90 the outcome of the meet operation. If a variable V_i has an
91 UNDEFINED value, it means that either its defining statement
92 hasn't been visited yet or V_i has no defining statement, in
93 which case the original symbol 'V' is being used
94 uninitialized. Since 'V' is a local variable, the compiler
95 may assume any initial value for it.
98 After propagation, every variable V_i that ends up with a lattice
99 value of CONSTANT will have the associated constant value in the
100 array CONST_VAL[i].VALUE. That is fed into substitute_and_fold for
101 final substitution and folding.
104 Constant propagation in stores and loads (STORE-CCP)
105 ----------------------------------------------------
107 While CCP has all the logic to propagate constants in GIMPLE
108 registers, it is missing the ability to associate constants with
109 stores and loads (i.e., pointer dereferences, structures and
110 global/aliased variables). We don't keep loads and stores in
111 SSA, but we do build a factored use-def web for them (in the
114 For instance, consider the following code fragment:
133 We should be able to deduce that the predicate 'a.a != B' is always
134 false. To achieve this, we associate constant values to the SSA
135 names in the VDEF operands for each store. Additionally,
136 since we also glob partial loads/stores with the base symbol, we
137 also keep track of the memory reference where the constant value
138 was stored (in the MEM_REF field of PROP_VALUE_T). For instance,
146 In the example above, CCP will associate value '2' with 'a_5', but
147 it would be wrong to replace the load from 'a.b' with '2', because
148 '2' had been stored into a.a.
150 Note that the initial value of virtual operands is VARYING, not
151 UNDEFINED. Consider, for instance global variables:
159 # A_5 = PHI (A_4, A_2);
167 The value of A_2 cannot be assumed to be UNDEFINED, as it may have
168 been defined outside of foo. If we were to assume it UNDEFINED, we
169 would erroneously optimize the above into 'return 3;'.
171 Though STORE-CCP is not too expensive, it does have to do more work
172 than regular CCP, so it is only enabled at -O2. Both regular CCP
173 and STORE-CCP use the exact same algorithm. The only distinction
174 is that when doing STORE-CCP, the boolean variable DO_STORE_CCP is
175 set to true. This affects the evaluation of statements and PHI
180 Constant propagation with conditional branches,
181 Wegman and Zadeck, ACM TOPLAS 13(2):181-210.
183 Building an Optimizing Compiler,
184 Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9.
186 Advanced Compiler Design and Implementation,
187 Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */
191 #include "coretypes.h"
198 #include "basic-block.h"
201 #include "function.h"
202 #include "diagnostic.h"
204 #include "tree-dump.h"
205 #include "tree-flow.h"
206 #include "tree-pass.h"
207 #include "tree-ssa-propagate.h"
208 #include "langhooks.h"
213 /* Possible lattice values. */
222 /* Array of propagated constant values. After propagation,
223 CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If
224 the constant is held in an SSA name representing a memory store
225 (i.e., a VDEF), CONST_VAL[I].MEM_REF will contain the actual
226 memory reference used to store (i.e., the LHS of the assignment
228 static prop_value_t *const_val;
230 /* True if we are also propagating constants in stores and loads. */
231 static bool do_store_ccp;
233 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */
236 dump_lattice_value (FILE *outf, const char *prefix, prop_value_t val)
238 switch (val.lattice_val)
241 fprintf (outf, "%sUNINITIALIZED", prefix);
244 fprintf (outf, "%sUNDEFINED", prefix);
247 fprintf (outf, "%sVARYING", prefix);
250 fprintf (outf, "%sCONSTANT ", prefix);
251 print_generic_expr (outf, val.value, dump_flags);
259 /* Print lattice value VAL to stderr. */
261 void debug_lattice_value (prop_value_t val);
264 debug_lattice_value (prop_value_t val)
266 dump_lattice_value (stderr, "", val);
267 fprintf (stderr, "\n");
271 /* The regular is_gimple_min_invariant does a shallow test of the object.
272 It assumes that full gimplification has happened, or will happen on the
273 object. For a value coming from DECL_INITIAL, this is not true, so we
274 have to be more strict ourselves. */
277 ccp_decl_initial_min_invariant (tree t)
279 if (!is_gimple_min_invariant (t))
281 if (TREE_CODE (t) == ADDR_EXPR)
283 /* Inline and unroll is_gimple_addressable. */
286 t = TREE_OPERAND (t, 0);
287 if (is_gimple_id (t))
289 if (!handled_component_p (t))
296 /* If SYM is a constant variable with known value, return the value.
297 NULL_TREE is returned otherwise. */
300 get_symbol_constant_value (tree sym)
302 if (TREE_STATIC (sym)
303 && TREE_READONLY (sym)
306 tree val = DECL_INITIAL (sym);
308 && ccp_decl_initial_min_invariant (val))
315 /* Compute a default value for variable VAR and store it in the
316 CONST_VAL array. The following rules are used to get default
319 1- Global and static variables that are declared constant are
322 2- Any other value is considered UNDEFINED. This is useful when
323 considering PHI nodes. PHI arguments that are undefined do not
324 change the constant value of the PHI node, which allows for more
325 constants to be propagated.
327 3- If SSA_NAME_VALUE is set and it is a constant, its value is
330 4- Variables defined by statements other than assignments and PHI
331 nodes are considered VARYING.
333 5- Initial values of variables that are not GIMPLE registers are
334 considered VARYING. */
337 get_default_value (tree var)
339 tree sym = SSA_NAME_VAR (var);
340 prop_value_t val = { UNINITIALIZED, NULL_TREE, NULL_TREE };
343 if (!do_store_ccp && !is_gimple_reg (var))
345 /* Short circuit for regular CCP. We are not interested in any
346 non-register when DO_STORE_CCP is false. */
347 val.lattice_val = VARYING;
349 else if (SSA_NAME_VALUE (var)
350 && is_gimple_min_invariant (SSA_NAME_VALUE (var)))
352 val.lattice_val = CONSTANT;
353 val.value = SSA_NAME_VALUE (var);
355 else if ((cst_val = get_symbol_constant_value (sym)) != NULL_TREE)
357 /* Globals and static variables declared 'const' take their
359 val.lattice_val = CONSTANT;
365 tree stmt = SSA_NAME_DEF_STMT (var);
367 if (IS_EMPTY_STMT (stmt))
369 /* Variables defined by an empty statement are those used
370 before being initialized. If VAR is a local variable, we
371 can assume initially that it is UNDEFINED, otherwise we must
372 consider it VARYING. */
373 if (is_gimple_reg (sym) && TREE_CODE (sym) != PARM_DECL)
374 val.lattice_val = UNDEFINED;
376 val.lattice_val = VARYING;
378 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
379 || TREE_CODE (stmt) == PHI_NODE)
381 /* Any other variable defined by an assignment or a PHI node
382 is considered UNDEFINED. */
383 val.lattice_val = UNDEFINED;
387 /* Otherwise, VAR will never take on a constant value. */
388 val.lattice_val = VARYING;
396 /* Get the constant value associated with variable VAR. */
398 static inline prop_value_t *
401 prop_value_t *val = &const_val[SSA_NAME_VERSION (var)];
403 if (val->lattice_val == UNINITIALIZED)
404 *val = get_default_value (var);
409 /* Sets the value associated with VAR to VARYING. */
412 set_value_varying (tree var)
414 prop_value_t *val = &const_val[SSA_NAME_VERSION (var)];
416 val->lattice_val = VARYING;
417 val->value = NULL_TREE;
418 val->mem_ref = NULL_TREE;
421 /* For float types, modify the value of VAL to make ccp work correctly
422 for non-standard values (-0, NaN):
424 If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0.
425 If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED.
426 This is to fix the following problem (see PR 29921): Suppose we have
430 and we set value of y to NaN. This causes value of x to be set to NaN.
431 When we later determine that y is in fact VARYING, fold uses the fact
432 that HONOR_NANS is false, and we try to change the value of x to 0,
433 causing an ICE. With HONOR_NANS being false, the real appearance of
434 NaN would cause undefined behavior, though, so claiming that y (and x)
435 are UNDEFINED initially is correct. */
438 canonicalize_float_value (prop_value_t *val)
440 enum machine_mode mode;
444 if (val->lattice_val != CONSTANT
445 || TREE_CODE (val->value) != REAL_CST)
448 d = TREE_REAL_CST (val->value);
449 type = TREE_TYPE (val->value);
450 mode = TYPE_MODE (type);
452 if (!HONOR_SIGNED_ZEROS (mode)
453 && REAL_VALUE_MINUS_ZERO (d))
455 val->value = build_real (type, dconst0);
459 if (!HONOR_NANS (mode)
460 && REAL_VALUE_ISNAN (d))
462 val->lattice_val = UNDEFINED;
469 /* Set the value for variable VAR to NEW_VAL. Return true if the new
470 value is different from VAR's previous value. */
473 set_lattice_value (tree var, prop_value_t new_val)
475 prop_value_t *old_val = get_value (var);
477 canonicalize_float_value (&new_val);
479 /* Lattice transitions must always be monotonically increasing in
480 value. If *OLD_VAL and NEW_VAL are the same, return false to
481 inform the caller that this was a non-transition. */
483 gcc_assert (old_val->lattice_val < new_val.lattice_val
484 || (old_val->lattice_val == new_val.lattice_val
485 && ((!old_val->value && !new_val.value)
486 || operand_equal_p (old_val->value, new_val.value, 0))
487 && old_val->mem_ref == new_val.mem_ref));
489 if (old_val->lattice_val != new_val.lattice_val)
491 if (dump_file && (dump_flags & TDF_DETAILS))
493 dump_lattice_value (dump_file, "Lattice value changed to ", new_val);
494 fprintf (dump_file, ". Adding SSA edges to worklist.\n");
499 gcc_assert (new_val.lattice_val != UNDEFINED);
507 /* Return the likely CCP lattice value for STMT.
509 If STMT has no operands, then return CONSTANT.
511 Else if any operands of STMT are undefined, then return UNDEFINED.
513 Else if any operands of STMT are constants, then return CONSTANT.
515 Else return VARYING. */
518 likely_value (tree stmt)
520 bool has_constant_operand;
525 ann = stmt_ann (stmt);
527 /* If the statement has volatile operands, it won't fold to a
529 if (ann->has_volatile_ops)
532 /* If we are not doing store-ccp, statements with loads
533 and/or stores will never fold into a constant. */
535 && !ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
539 /* A CALL_EXPR is assumed to be varying. NOTE: This may be overly
540 conservative, in the presence of const and pure calls. */
541 if (get_call_expr_in (stmt) != NULL_TREE)
544 /* Anything other than assignments and conditional jumps are not
545 interesting for CCP. */
546 if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT
547 && !(TREE_CODE (stmt) == RETURN_EXPR && get_rhs (stmt) != NULL_TREE)
548 && TREE_CODE (stmt) != COND_EXPR
549 && TREE_CODE (stmt) != SWITCH_EXPR)
552 if (is_gimple_min_invariant (get_rhs (stmt)))
555 has_constant_operand = false;
556 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
558 prop_value_t *val = get_value (use);
560 if (val->lattice_val == UNDEFINED)
563 if (val->lattice_val == CONSTANT)
564 has_constant_operand = true;
567 if (has_constant_operand
568 /* We do not consider virtual operands here -- load from read-only
569 memory may have only VARYING virtual operands, but still be
571 || ZERO_SSA_OPERANDS (stmt, SSA_OP_USE))
577 /* Returns true if STMT cannot be constant. */
580 surely_varying_stmt_p (tree stmt)
582 /* If the statement has operands that we cannot handle, it cannot be
584 if (stmt_ann (stmt)->has_volatile_ops)
587 if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
592 /* We can only handle simple loads and stores. */
593 if (!stmt_makes_single_load (stmt)
594 && !stmt_makes_single_store (stmt))
598 /* If it contains a call, it is varying. */
599 if (get_call_expr_in (stmt) != NULL_TREE)
602 /* Anything other than assignments and conditional jumps are not
603 interesting for CCP. */
604 if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT
605 && !(TREE_CODE (stmt) == RETURN_EXPR && get_rhs (stmt) != NULL_TREE)
606 && TREE_CODE (stmt) != COND_EXPR
607 && TREE_CODE (stmt) != SWITCH_EXPR)
613 /* Initialize local data structures for CCP. */
616 ccp_initialize (void)
620 const_val = XCNEWVEC (prop_value_t, num_ssa_names);
622 /* Initialize simulation flags for PHI nodes and statements. */
625 block_stmt_iterator i;
627 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
629 tree stmt = bsi_stmt (i);
630 bool is_varying = surely_varying_stmt_p (stmt);
637 /* If the statement will not produce a constant, mark
638 all its outputs VARYING. */
639 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
642 set_value_varying (def);
646 DONT_SIMULATE_AGAIN (stmt) = is_varying;
650 /* Now process PHI nodes. We never set DONT_SIMULATE_AGAIN on phi node,
651 since we do not know which edges are executable yet, except for
652 phi nodes for virtual operands when we do not do store ccp. */
657 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
659 if (!do_store_ccp && !is_gimple_reg (PHI_RESULT (phi)))
660 DONT_SIMULATE_AGAIN (phi) = true;
662 DONT_SIMULATE_AGAIN (phi) = false;
668 /* Do final substitution of propagated values, cleanup the flowgraph and
669 free allocated storage.
671 Return TRUE when something was optimized. */
676 /* Perform substitutions based on the known constant values. */
677 bool something_changed = substitute_and_fold (const_val, false);
680 return something_changed;;
684 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
687 any M UNDEFINED = any
688 any M VARYING = VARYING
689 Ci M Cj = Ci if (i == j)
690 Ci M Cj = VARYING if (i != j)
694 ccp_lattice_meet (prop_value_t *val1, prop_value_t *val2)
696 if (val1->lattice_val == UNDEFINED)
698 /* UNDEFINED M any = any */
701 else if (val2->lattice_val == UNDEFINED)
703 /* any M UNDEFINED = any
704 Nothing to do. VAL1 already contains the value we want. */
707 else if (val1->lattice_val == VARYING
708 || val2->lattice_val == VARYING)
710 /* any M VARYING = VARYING. */
711 val1->lattice_val = VARYING;
712 val1->value = NULL_TREE;
713 val1->mem_ref = NULL_TREE;
715 else if (val1->lattice_val == CONSTANT
716 && val2->lattice_val == CONSTANT
717 && simple_cst_equal (val1->value, val2->value) == 1
719 || (val1->mem_ref && val2->mem_ref
720 && operand_equal_p (val1->mem_ref, val2->mem_ref, 0))))
722 /* Ci M Cj = Ci if (i == j)
723 Ci M Cj = VARYING if (i != j)
725 If these two values come from memory stores, make sure that
726 they come from the same memory reference. */
727 val1->lattice_val = CONSTANT;
728 val1->value = val1->value;
729 val1->mem_ref = val1->mem_ref;
733 /* Any other combination is VARYING. */
734 val1->lattice_val = VARYING;
735 val1->value = NULL_TREE;
736 val1->mem_ref = NULL_TREE;
741 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
742 lattice values to determine PHI_NODE's lattice value. The value of a
743 PHI node is determined calling ccp_lattice_meet with all the arguments
744 of the PHI node that are incoming via executable edges. */
746 static enum ssa_prop_result
747 ccp_visit_phi_node (tree phi)
750 prop_value_t *old_val, new_val;
752 if (dump_file && (dump_flags & TDF_DETAILS))
754 fprintf (dump_file, "\nVisiting PHI node: ");
755 print_generic_expr (dump_file, phi, dump_flags);
758 old_val = get_value (PHI_RESULT (phi));
759 switch (old_val->lattice_val)
762 return SSA_PROP_VARYING;
769 new_val.lattice_val = UNDEFINED;
770 new_val.value = NULL_TREE;
771 new_val.mem_ref = NULL_TREE;
778 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
780 /* Compute the meet operator over all the PHI arguments flowing
781 through executable edges. */
782 edge e = PHI_ARG_EDGE (phi, i);
784 if (dump_file && (dump_flags & TDF_DETAILS))
787 "\n Argument #%d (%d -> %d %sexecutable)\n",
788 i, e->src->index, e->dest->index,
789 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
792 /* If the incoming edge is executable, Compute the meet operator for
793 the existing value of the PHI node and the current PHI argument. */
794 if (e->flags & EDGE_EXECUTABLE)
796 tree arg = PHI_ARG_DEF (phi, i);
797 prop_value_t arg_val;
799 if (is_gimple_min_invariant (arg))
801 arg_val.lattice_val = CONSTANT;
803 arg_val.mem_ref = NULL_TREE;
806 arg_val = *(get_value (arg));
808 ccp_lattice_meet (&new_val, &arg_val);
810 if (dump_file && (dump_flags & TDF_DETAILS))
812 fprintf (dump_file, "\t");
813 print_generic_expr (dump_file, arg, dump_flags);
814 dump_lattice_value (dump_file, "\tValue: ", arg_val);
815 fprintf (dump_file, "\n");
818 if (new_val.lattice_val == VARYING)
823 if (dump_file && (dump_flags & TDF_DETAILS))
825 dump_lattice_value (dump_file, "\n PHI node value: ", new_val);
826 fprintf (dump_file, "\n\n");
829 /* Make the transition to the new value. */
830 if (set_lattice_value (PHI_RESULT (phi), new_val))
832 if (new_val.lattice_val == VARYING)
833 return SSA_PROP_VARYING;
835 return SSA_PROP_INTERESTING;
838 return SSA_PROP_NOT_INTERESTING;
842 /* CCP specific front-end to the non-destructive constant folding
845 Attempt to simplify the RHS of STMT knowing that one or more
846 operands are constants.
848 If simplification is possible, return the simplified RHS,
849 otherwise return the original RHS. */
854 tree rhs = get_rhs (stmt);
855 enum tree_code code = TREE_CODE (rhs);
856 enum tree_code_class kind = TREE_CODE_CLASS (code);
857 tree retval = NULL_TREE;
859 if (TREE_CODE (rhs) == SSA_NAME)
861 /* If the RHS is an SSA_NAME, return its known constant value,
863 return get_value (rhs)->value;
865 else if (do_store_ccp && stmt_makes_single_load (stmt))
867 /* If the RHS is a memory load, see if the VUSEs associated with
868 it are a valid constant for that memory load. */
869 prop_value_t *val = get_value_loaded_by (stmt, const_val);
870 if (val && val->mem_ref)
872 if (operand_equal_p (val->mem_ref, rhs, 0))
875 /* If RHS is extracting REALPART_EXPR or IMAGPART_EXPR of a
876 complex type with a known constant value, return it. */
877 if ((TREE_CODE (rhs) == REALPART_EXPR
878 || TREE_CODE (rhs) == IMAGPART_EXPR)
879 && operand_equal_p (val->mem_ref, TREE_OPERAND (rhs, 0), 0))
880 return fold_build1 (TREE_CODE (rhs), TREE_TYPE (rhs), val->value);
885 /* Unary operators. Note that we know the single operand must
886 be a constant. So this should almost always return a
888 if (kind == tcc_unary)
890 /* Handle unary operators which can appear in GIMPLE form. */
891 tree op0 = TREE_OPERAND (rhs, 0);
893 /* Simplify the operand down to a constant. */
894 if (TREE_CODE (op0) == SSA_NAME)
896 prop_value_t *val = get_value (op0);
897 if (val->lattice_val == CONSTANT)
898 op0 = get_value (op0)->value;
901 if ((code == NOP_EXPR || code == CONVERT_EXPR)
902 && useless_type_conversion_p (TREE_TYPE (rhs), TREE_TYPE (op0)))
904 return fold_unary (code, TREE_TYPE (rhs), op0);
907 /* Binary and comparison operators. We know one or both of the
908 operands are constants. */
909 else if (kind == tcc_binary
910 || kind == tcc_comparison
911 || code == TRUTH_AND_EXPR
912 || code == TRUTH_OR_EXPR
913 || code == TRUTH_XOR_EXPR)
915 /* Handle binary and comparison operators that can appear in
917 tree op0 = TREE_OPERAND (rhs, 0);
918 tree op1 = TREE_OPERAND (rhs, 1);
920 /* Simplify the operands down to constants when appropriate. */
921 if (TREE_CODE (op0) == SSA_NAME)
923 prop_value_t *val = get_value (op0);
924 if (val->lattice_val == CONSTANT)
928 if (TREE_CODE (op1) == SSA_NAME)
930 prop_value_t *val = get_value (op1);
931 if (val->lattice_val == CONSTANT)
935 return fold_binary (code, TREE_TYPE (rhs), op0, op1);
938 /* We may be able to fold away calls to builtin functions if their
939 arguments are constants. */
940 else if (code == CALL_EXPR
941 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
942 && TREE_CODE (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)) == FUNCTION_DECL
943 && DECL_BUILT_IN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
945 if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_USE))
952 /* Preserve the original values of every operand. */
953 orig = XNEWVEC (tree, NUM_SSA_OPERANDS (stmt, SSA_OP_USE));
954 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE)
957 /* Substitute operands with their values and try to fold. */
958 replace_uses_in (stmt, NULL, const_val);
959 retval = fold_call_expr (rhs, false);
961 /* Restore operands to their original form. */
963 FOR_EACH_SSA_USE_OPERAND (var_p, stmt, iter, SSA_OP_USE)
964 SET_USE (var_p, orig[i++]);
971 /* If we got a simplified form, see if we need to convert its type. */
973 return fold_convert (TREE_TYPE (rhs), retval);
975 /* No simplification was possible. */
980 /* Return the tree representing the element referenced by T if T is an
981 ARRAY_REF or COMPONENT_REF into constant aggregates. Return
982 NULL_TREE otherwise. */
985 fold_const_aggregate_ref (tree t)
988 tree base, ctor, idx, field;
989 unsigned HOST_WIDE_INT cnt;
992 switch (TREE_CODE (t))
995 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
996 DECL_INITIAL. If BASE is a nested reference into another
997 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
998 the inner reference. */
999 base = TREE_OPERAND (t, 0);
1000 switch (TREE_CODE (base))
1003 if (!TREE_READONLY (base)
1004 || TREE_CODE (TREE_TYPE (base)) != ARRAY_TYPE
1005 || !targetm.binds_local_p (base))
1008 ctor = DECL_INITIAL (base);
1013 ctor = fold_const_aggregate_ref (base);
1020 if (ctor == NULL_TREE
1021 || (TREE_CODE (ctor) != CONSTRUCTOR
1022 && TREE_CODE (ctor) != STRING_CST)
1023 || !TREE_STATIC (ctor))
1026 /* Get the index. If we have an SSA_NAME, try to resolve it
1027 with the current lattice value for the SSA_NAME. */
1028 idx = TREE_OPERAND (t, 1);
1029 switch (TREE_CODE (idx))
1032 if ((value = get_value (idx))
1033 && value->lattice_val == CONSTANT
1034 && TREE_CODE (value->value) == INTEGER_CST)
1047 /* Fold read from constant string. */
1048 if (TREE_CODE (ctor) == STRING_CST)
1050 if ((TYPE_MODE (TREE_TYPE (t))
1051 == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1052 && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1054 && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) == 1
1055 && compare_tree_int (idx, TREE_STRING_LENGTH (ctor)) < 0)
1056 return fold_convert (TREE_TYPE (t),
1057 build_int_cst (NULL,
1058 (TREE_STRING_POINTER (ctor)
1059 [TREE_INT_CST_LOW (idx)])));
1063 /* Whoo-hoo! I'll fold ya baby. Yeah! */
1064 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
1065 if (tree_int_cst_equal (cfield, idx))
1070 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1071 DECL_INITIAL. If BASE is a nested reference into another
1072 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1073 the inner reference. */
1074 base = TREE_OPERAND (t, 0);
1075 switch (TREE_CODE (base))
1078 if (!TREE_READONLY (base)
1079 || TREE_CODE (TREE_TYPE (base)) != RECORD_TYPE
1080 || !targetm.binds_local_p (base))
1083 ctor = DECL_INITIAL (base);
1088 ctor = fold_const_aggregate_ref (base);
1095 if (ctor == NULL_TREE
1096 || TREE_CODE (ctor) != CONSTRUCTOR
1097 || !TREE_STATIC (ctor))
1100 field = TREE_OPERAND (t, 1);
1102 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
1104 /* FIXME: Handle bit-fields. */
1105 && ! DECL_BIT_FIELD (cfield))
1112 tree c = fold_const_aggregate_ref (TREE_OPERAND (t, 0));
1113 if (c && TREE_CODE (c) == COMPLEX_CST)
1114 return fold_build1 (TREE_CODE (t), TREE_TYPE (t), c);
1125 /* Evaluate statement STMT. */
1128 evaluate_stmt (tree stmt)
1131 tree simplified = NULL_TREE;
1132 ccp_lattice_t likelyvalue = likely_value (stmt);
1135 val.mem_ref = NULL_TREE;
1137 fold_defer_overflow_warnings ();
1139 /* If the statement is likely to have a CONSTANT result, then try
1140 to fold the statement to determine the constant value. */
1141 if (likelyvalue == CONSTANT)
1142 simplified = ccp_fold (stmt);
1143 /* If the statement is likely to have a VARYING result, then do not
1144 bother folding the statement. */
1145 if (likelyvalue == VARYING)
1146 simplified = get_rhs (stmt);
1147 /* If the statement is an ARRAY_REF or COMPONENT_REF into constant
1148 aggregates, extract the referenced constant. Otherwise the
1149 statement is likely to have an UNDEFINED value, and there will be
1150 nothing to do. Note that fold_const_aggregate_ref returns
1151 NULL_TREE if the first case does not match. */
1152 else if (!simplified)
1153 simplified = fold_const_aggregate_ref (get_rhs (stmt));
1155 is_constant = simplified && is_gimple_min_invariant (simplified);
1157 fold_undefer_overflow_warnings (is_constant, stmt, 0);
1161 /* The statement produced a constant value. */
1162 val.lattice_val = CONSTANT;
1163 val.value = simplified;
1167 /* The statement produced a nonconstant value. If the statement
1168 had UNDEFINED operands, then the result of the statement
1169 should be UNDEFINED. Otherwise, the statement is VARYING. */
1170 if (likelyvalue == UNDEFINED)
1171 val.lattice_val = likelyvalue;
1173 val.lattice_val = VARYING;
1175 val.value = NULL_TREE;
1182 /* Visit the assignment statement STMT. Set the value of its LHS to the
1183 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
1184 creates virtual definitions, set the value of each new name to that
1185 of the RHS (if we can derive a constant out of the RHS). */
1187 static enum ssa_prop_result
1188 visit_assignment (tree stmt, tree *output_p)
1192 enum ssa_prop_result retval;
1194 lhs = GIMPLE_STMT_OPERAND (stmt, 0);
1195 rhs = GIMPLE_STMT_OPERAND (stmt, 1);
1197 if (TREE_CODE (rhs) == SSA_NAME)
1199 /* For a simple copy operation, we copy the lattice values. */
1200 prop_value_t *nval = get_value (rhs);
1203 else if (do_store_ccp && stmt_makes_single_load (stmt))
1205 /* Same as above, but the RHS is not a gimple register and yet
1206 has a known VUSE. If STMT is loading from the same memory
1207 location that created the SSA_NAMEs for the virtual operands,
1208 we can propagate the value on the RHS. */
1209 prop_value_t *nval = get_value_loaded_by (stmt, const_val);
1213 && operand_equal_p (nval->mem_ref, rhs, 0))
1216 val = evaluate_stmt (stmt);
1219 /* Evaluate the statement. */
1220 val = evaluate_stmt (stmt);
1222 /* If the original LHS was a VIEW_CONVERT_EXPR, modify the constant
1223 value to be a VIEW_CONVERT_EXPR of the old constant value.
1225 ??? Also, if this was a definition of a bitfield, we need to widen
1226 the constant value into the type of the destination variable. This
1227 should not be necessary if GCC represented bitfields properly. */
1229 tree orig_lhs = GIMPLE_STMT_OPERAND (stmt, 0);
1231 if (TREE_CODE (orig_lhs) == VIEW_CONVERT_EXPR
1232 && val.lattice_val == CONSTANT)
1234 tree w = fold_unary (VIEW_CONVERT_EXPR,
1235 TREE_TYPE (TREE_OPERAND (orig_lhs, 0)),
1238 orig_lhs = TREE_OPERAND (orig_lhs, 0);
1239 if (w && is_gimple_min_invariant (w))
1243 val.lattice_val = VARYING;
1248 if (val.lattice_val == CONSTANT
1249 && TREE_CODE (orig_lhs) == COMPONENT_REF
1250 && DECL_BIT_FIELD (TREE_OPERAND (orig_lhs, 1)))
1252 tree w = widen_bitfield (val.value, TREE_OPERAND (orig_lhs, 1),
1255 if (w && is_gimple_min_invariant (w))
1259 val.lattice_val = VARYING;
1260 val.value = NULL_TREE;
1261 val.mem_ref = NULL_TREE;
1266 retval = SSA_PROP_NOT_INTERESTING;
1268 /* Set the lattice value of the statement's output. */
1269 if (TREE_CODE (lhs) == SSA_NAME)
1271 /* If STMT is an assignment to an SSA_NAME, we only have one
1273 if (set_lattice_value (lhs, val))
1276 if (val.lattice_val == VARYING)
1277 retval = SSA_PROP_VARYING;
1279 retval = SSA_PROP_INTERESTING;
1282 else if (do_store_ccp && stmt_makes_single_store (stmt))
1284 /* Otherwise, set the names in VDEF operands to the new
1285 constant value and mark the LHS as the memory reference
1286 associated with VAL. */
1291 /* Mark VAL as stored in the LHS of this assignment. */
1292 if (val.lattice_val == CONSTANT)
1295 /* Set the value of every VDEF to VAL. */
1297 FOR_EACH_SSA_TREE_OPERAND (vdef, stmt, i, SSA_OP_VIRTUAL_DEFS)
1299 /* See PR 29801. We may have VDEFs for read-only variables
1300 (see the handling of unmodifiable variables in
1301 add_virtual_operand); do not attempt to change their value. */
1302 if (get_symbol_constant_value (SSA_NAME_VAR (vdef)) != NULL_TREE)
1305 changed |= set_lattice_value (vdef, val);
1308 /* Note that for propagation purposes, we are only interested in
1309 visiting statements that load the exact same memory reference
1310 stored here. Those statements will have the exact same list
1311 of virtual uses, so it is enough to set the output of this
1312 statement to be its first virtual definition. */
1313 *output_p = first_vdef (stmt);
1316 if (val.lattice_val == VARYING)
1317 retval = SSA_PROP_VARYING;
1319 retval = SSA_PROP_INTERESTING;
1327 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
1328 if it can determine which edge will be taken. Otherwise, return
1329 SSA_PROP_VARYING. */
1331 static enum ssa_prop_result
1332 visit_cond_stmt (tree stmt, edge *taken_edge_p)
1337 block = bb_for_stmt (stmt);
1338 val = evaluate_stmt (stmt);
1340 /* Find which edge out of the conditional block will be taken and add it
1341 to the worklist. If no single edge can be determined statically,
1342 return SSA_PROP_VARYING to feed all the outgoing edges to the
1343 propagation engine. */
1344 *taken_edge_p = val.value ? find_taken_edge (block, val.value) : 0;
1346 return SSA_PROP_INTERESTING;
1348 return SSA_PROP_VARYING;
1352 /* Evaluate statement STMT. If the statement produces an output value and
1353 its evaluation changes the lattice value of its output, return
1354 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
1357 If STMT is a conditional branch and we can determine its truth
1358 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
1359 value, return SSA_PROP_VARYING. */
1361 static enum ssa_prop_result
1362 ccp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
1367 if (dump_file && (dump_flags & TDF_DETAILS))
1369 fprintf (dump_file, "\nVisiting statement:\n");
1370 print_generic_stmt (dump_file, stmt, dump_flags);
1371 fprintf (dump_file, "\n");
1374 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
1376 /* If the statement is an assignment that produces a single
1377 output value, evaluate its RHS to see if the lattice value of
1378 its output has changed. */
1379 return visit_assignment (stmt, output_p);
1381 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
1383 /* If STMT is a conditional branch, see if we can determine
1384 which branch will be taken. */
1385 return visit_cond_stmt (stmt, taken_edge_p);
1388 /* Any other kind of statement is not interesting for constant
1389 propagation and, therefore, not worth simulating. */
1390 if (dump_file && (dump_flags & TDF_DETAILS))
1391 fprintf (dump_file, "No interesting values produced. Marked VARYING.\n");
1393 /* Definitions made by statements other than assignments to
1394 SSA_NAMEs represent unknown modifications to their outputs.
1395 Mark them VARYING. */
1396 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
1398 prop_value_t v = { VARYING, NULL_TREE, NULL_TREE };
1399 set_lattice_value (def, v);
1402 return SSA_PROP_VARYING;
1406 /* Main entry point for SSA Conditional Constant Propagation. */
1409 execute_ssa_ccp (bool store_ccp)
1411 do_store_ccp = store_ccp;
1413 ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node);
1414 if (ccp_finalize ())
1415 return (TODO_cleanup_cfg | TODO_update_ssa | TODO_remove_unused_locals);
1424 return execute_ssa_ccp (false);
1431 return flag_tree_ccp != 0;
1435 struct tree_opt_pass pass_ccp =
1438 gate_ccp, /* gate */
1439 do_ssa_ccp, /* execute */
1442 0, /* static_pass_number */
1443 TV_TREE_CCP, /* tv_id */
1444 PROP_cfg | PROP_ssa, /* properties_required */
1445 0, /* properties_provided */
1446 0, /* properties_destroyed */
1447 0, /* todo_flags_start */
1448 TODO_dump_func | TODO_verify_ssa
1449 | TODO_verify_stmts | TODO_ggc_collect,/* todo_flags_finish */
1455 do_ssa_store_ccp (void)
1457 /* If STORE-CCP is not enabled, we just run regular CCP. */
1458 return execute_ssa_ccp (flag_tree_store_ccp != 0);
1462 gate_store_ccp (void)
1464 /* STORE-CCP is enabled only with -ftree-store-ccp, but when
1465 -fno-tree-store-ccp is specified, we should run regular CCP.
1466 That's why the pass is enabled with either flag. */
1467 return flag_tree_store_ccp != 0 || flag_tree_ccp != 0;
1471 struct tree_opt_pass pass_store_ccp =
1473 "store_ccp", /* name */
1474 gate_store_ccp, /* gate */
1475 do_ssa_store_ccp, /* execute */
1478 0, /* static_pass_number */
1479 TV_TREE_STORE_CCP, /* tv_id */
1480 PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
1481 0, /* properties_provided */
1482 0, /* properties_destroyed */
1483 0, /* todo_flags_start */
1484 TODO_dump_func | TODO_verify_ssa
1485 | TODO_verify_stmts | TODO_ggc_collect,/* todo_flags_finish */
1489 /* Given a constant value VAL for bitfield FIELD, and a destination
1490 variable VAR, return VAL appropriately widened to fit into VAR. If
1491 FIELD is wider than HOST_WIDE_INT, NULL is returned. */
1494 widen_bitfield (tree val, tree field, tree var)
1496 unsigned HOST_WIDE_INT var_size, field_size;
1498 unsigned HOST_WIDE_INT mask;
1501 /* We can only do this if the size of the type and field and VAL are
1502 all constants representable in HOST_WIDE_INT. */
1503 if (!host_integerp (TYPE_SIZE (TREE_TYPE (var)), 1)
1504 || !host_integerp (DECL_SIZE (field), 1)
1505 || !host_integerp (val, 0))
1508 var_size = tree_low_cst (TYPE_SIZE (TREE_TYPE (var)), 1);
1509 field_size = tree_low_cst (DECL_SIZE (field), 1);
1511 /* Give up if either the bitfield or the variable are too wide. */
1512 if (field_size > HOST_BITS_PER_WIDE_INT || var_size > HOST_BITS_PER_WIDE_INT)
1515 gcc_assert (var_size >= field_size);
1517 /* If the sign bit of the value is not set or the field's type is unsigned,
1518 just mask off the high order bits of the value. */
1519 if (DECL_UNSIGNED (field)
1520 || !(tree_low_cst (val, 0) & (((HOST_WIDE_INT)1) << (field_size - 1))))
1522 /* Zero extension. Build a mask with the lower 'field_size' bits
1523 set and a BIT_AND_EXPR node to clear the high order bits of
1525 for (i = 0, mask = 0; i < field_size; i++)
1526 mask |= ((HOST_WIDE_INT) 1) << i;
1528 wide_val = fold_build2 (BIT_AND_EXPR, TREE_TYPE (var), val,
1529 build_int_cst (TREE_TYPE (var), mask));
1533 /* Sign extension. Create a mask with the upper 'field_size'
1534 bits set and a BIT_IOR_EXPR to set the high order bits of the
1536 for (i = 0, mask = 0; i < (var_size - field_size); i++)
1537 mask |= ((HOST_WIDE_INT) 1) << (var_size - i - 1);
1539 wide_val = fold_build2 (BIT_IOR_EXPR, TREE_TYPE (var), val,
1540 build_int_cst (TREE_TYPE (var), mask));
1547 /* A subroutine of fold_stmt_r. Attempts to fold *(A+O) to A[X].
1548 BASE is an array type. OFFSET is a byte displacement. ORIG_TYPE
1549 is the desired result type. */
1552 maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type)
1554 tree min_idx, idx, idx_type, elt_offset = integer_zero_node;
1555 tree array_type, elt_type, elt_size;
1557 /* If BASE is an ARRAY_REF, we can pick up another offset (this time
1558 measured in units of the size of elements type) from that ARRAY_REF).
1559 We can't do anything if either is variable.
1561 The case we handle here is *(&A[N]+O). */
1562 if (TREE_CODE (base) == ARRAY_REF)
1564 tree low_bound = array_ref_low_bound (base);
1566 elt_offset = TREE_OPERAND (base, 1);
1567 if (TREE_CODE (low_bound) != INTEGER_CST
1568 || TREE_CODE (elt_offset) != INTEGER_CST)
1571 elt_offset = int_const_binop (MINUS_EXPR, elt_offset, low_bound, 0);
1572 base = TREE_OPERAND (base, 0);
1575 /* Ignore stupid user tricks of indexing non-array variables. */
1576 array_type = TREE_TYPE (base);
1577 if (TREE_CODE (array_type) != ARRAY_TYPE)
1579 elt_type = TREE_TYPE (array_type);
1580 if (!useless_type_conversion_p (orig_type, elt_type))
1583 /* Use signed size type for intermediate computation on the index. */
1584 idx_type = signed_type_for (size_type_node);
1586 /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the
1587 element type (so we can use the alignment if it's not constant).
1588 Otherwise, compute the offset as an index by using a division. If the
1589 division isn't exact, then don't do anything. */
1590 elt_size = TYPE_SIZE_UNIT (elt_type);
1593 if (integer_zerop (offset))
1595 if (TREE_CODE (elt_size) != INTEGER_CST)
1596 elt_size = size_int (TYPE_ALIGN (elt_type));
1598 idx = build_int_cst (idx_type, 0);
1602 unsigned HOST_WIDE_INT lquo, lrem;
1603 HOST_WIDE_INT hquo, hrem;
1606 /* The final array offset should be signed, so we need
1607 to sign-extend the (possibly pointer) offset here
1608 and use signed division. */
1609 soffset = double_int_sext (tree_to_double_int (offset),
1610 TYPE_PRECISION (TREE_TYPE (offset)));
1611 if (TREE_CODE (elt_size) != INTEGER_CST
1612 || div_and_round_double (TRUNC_DIV_EXPR, 0,
1613 soffset.low, soffset.high,
1614 TREE_INT_CST_LOW (elt_size),
1615 TREE_INT_CST_HIGH (elt_size),
1616 &lquo, &hquo, &lrem, &hrem)
1620 idx = build_int_cst_wide (idx_type, lquo, hquo);
1623 /* Assume the low bound is zero. If there is a domain type, get the
1624 low bound, if any, convert the index into that type, and add the
1626 min_idx = build_int_cst (idx_type, 0);
1627 if (TYPE_DOMAIN (array_type))
1629 idx_type = TYPE_DOMAIN (array_type);
1630 if (TYPE_MIN_VALUE (idx_type))
1631 min_idx = TYPE_MIN_VALUE (idx_type);
1633 min_idx = fold_convert (idx_type, min_idx);
1635 if (TREE_CODE (min_idx) != INTEGER_CST)
1638 elt_offset = fold_convert (idx_type, elt_offset);
1641 if (!integer_zerop (min_idx))
1642 idx = int_const_binop (PLUS_EXPR, idx, min_idx, 0);
1643 if (!integer_zerop (elt_offset))
1644 idx = int_const_binop (PLUS_EXPR, idx, elt_offset, 0);
1646 /* Make sure to possibly truncate late after offsetting. */
1647 idx = fold_convert (idx_type, idx);
1649 return build4 (ARRAY_REF, orig_type, base, idx, NULL_TREE, NULL_TREE);
1653 /* Attempt to fold *(S+O) to S.X.
1654 BASE is a record type. OFFSET is a byte displacement. ORIG_TYPE
1655 is the desired result type. */
1658 maybe_fold_offset_to_component_ref (tree record_type, tree base, tree offset,
1659 tree orig_type, bool base_is_ptr)
1661 tree f, t, field_type, tail_array_field, field_offset;
1665 if (TREE_CODE (record_type) != RECORD_TYPE
1666 && TREE_CODE (record_type) != UNION_TYPE
1667 && TREE_CODE (record_type) != QUAL_UNION_TYPE)
1670 /* Short-circuit silly cases. */
1671 if (useless_type_conversion_p (record_type, orig_type))
1674 tail_array_field = NULL_TREE;
1675 for (f = TYPE_FIELDS (record_type); f ; f = TREE_CHAIN (f))
1679 if (TREE_CODE (f) != FIELD_DECL)
1681 if (DECL_BIT_FIELD (f))
1684 if (!DECL_FIELD_OFFSET (f))
1686 field_offset = byte_position (f);
1687 if (TREE_CODE (field_offset) != INTEGER_CST)
1690 /* ??? Java creates "interesting" fields for representing base classes.
1691 They have no name, and have no context. With no context, we get into
1692 trouble with nonoverlapping_component_refs_p. Skip them. */
1693 if (!DECL_FIELD_CONTEXT (f))
1696 /* The previous array field isn't at the end. */
1697 tail_array_field = NULL_TREE;
1699 /* Check to see if this offset overlaps with the field. */
1700 cmp = tree_int_cst_compare (field_offset, offset);
1704 field_type = TREE_TYPE (f);
1706 /* Here we exactly match the offset being checked. If the types match,
1707 then we can return that field. */
1709 && useless_type_conversion_p (orig_type, field_type))
1712 base = build1 (INDIRECT_REF, record_type, base);
1713 t = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE);
1717 /* Don't care about offsets into the middle of scalars. */
1718 if (!AGGREGATE_TYPE_P (field_type))
1721 /* Check for array at the end of the struct. This is often
1722 used as for flexible array members. We should be able to
1723 turn this into an array access anyway. */
1724 if (TREE_CODE (field_type) == ARRAY_TYPE)
1725 tail_array_field = f;
1727 /* Check the end of the field against the offset. */
1728 if (!DECL_SIZE_UNIT (f)
1729 || TREE_CODE (DECL_SIZE_UNIT (f)) != INTEGER_CST)
1731 t = int_const_binop (MINUS_EXPR, offset, field_offset, 1);
1732 if (!tree_int_cst_lt (t, DECL_SIZE_UNIT (f)))
1735 /* If we matched, then set offset to the displacement into
1738 new_base = build1 (INDIRECT_REF, record_type, base);
1741 new_base = build3 (COMPONENT_REF, field_type, new_base, f, NULL_TREE);
1743 /* Recurse to possibly find the match. */
1744 ret = maybe_fold_offset_to_array_ref (new_base, t, orig_type);
1747 ret = maybe_fold_offset_to_component_ref (field_type, new_base, t,
1753 if (!tail_array_field)
1756 f = tail_array_field;
1757 field_type = TREE_TYPE (f);
1758 offset = int_const_binop (MINUS_EXPR, offset, byte_position (f), 1);
1760 /* If we get here, we've got an aggregate field, and a possibly
1761 nonzero offset into them. Recurse and hope for a valid match. */
1763 base = build1 (INDIRECT_REF, record_type, base);
1764 base = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE);
1766 t = maybe_fold_offset_to_array_ref (base, offset, orig_type);
1769 return maybe_fold_offset_to_component_ref (field_type, base, offset,
1773 /* Attempt to express (ORIG_TYPE)BASE+OFFSET as BASE->field_of_orig_type
1774 or BASE[index] or by combination of those.
1776 Before attempting the conversion strip off existing ADDR_EXPRs and
1777 handled component refs. */
1780 maybe_fold_offset_to_reference (tree base, tree offset, tree orig_type)
1784 bool base_is_ptr = true;
1787 if (TREE_CODE (base) == ADDR_EXPR)
1789 base_is_ptr = false;
1791 base = TREE_OPERAND (base, 0);
1793 /* Handle case where existing COMPONENT_REF pick e.g. wrong field of union,
1794 so it needs to be removed and new COMPONENT_REF constructed.
1795 The wrong COMPONENT_REF are often constructed by folding the
1796 (type *)&object within the expression (type *)&object+offset */
1797 if (handled_component_p (base) && 0)
1799 HOST_WIDE_INT sub_offset, size, maxsize;
1801 newbase = get_ref_base_and_extent (base, &sub_offset,
1803 gcc_assert (newbase);
1804 gcc_assert (!(sub_offset & (BITS_PER_UNIT - 1)));
1805 if (size == maxsize)
1809 offset = int_const_binop (PLUS_EXPR, offset,
1810 build_int_cst (TREE_TYPE (offset),
1811 sub_offset / BITS_PER_UNIT), 1);
1814 if (useless_type_conversion_p (orig_type, TREE_TYPE (base))
1815 && integer_zerop (offset))
1817 type = TREE_TYPE (base);
1822 if (!POINTER_TYPE_P (TREE_TYPE (base)))
1824 type = TREE_TYPE (TREE_TYPE (base));
1826 ret = maybe_fold_offset_to_component_ref (type, base, offset,
1827 orig_type, base_is_ptr);
1831 base = build1 (INDIRECT_REF, type, base);
1832 ret = maybe_fold_offset_to_array_ref (base, offset, orig_type);
1837 /* A subroutine of fold_stmt_r. Attempt to simplify *(BASE+OFFSET).
1838 Return the simplified expression, or NULL if nothing could be done. */
1841 maybe_fold_stmt_indirect (tree expr, tree base, tree offset)
1844 bool volatile_p = TREE_THIS_VOLATILE (expr);
1846 /* We may well have constructed a double-nested PLUS_EXPR via multiple
1847 substitutions. Fold that down to one. Remove NON_LVALUE_EXPRs that
1848 are sometimes added. */
1850 STRIP_TYPE_NOPS (base);
1851 TREE_OPERAND (expr, 0) = base;
1853 /* One possibility is that the address reduces to a string constant. */
1854 t = fold_read_from_constant_string (expr);
1858 /* Add in any offset from a POINTER_PLUS_EXPR. */
1859 if (TREE_CODE (base) == POINTER_PLUS_EXPR)
1863 offset2 = TREE_OPERAND (base, 1);
1864 if (TREE_CODE (offset2) != INTEGER_CST)
1866 base = TREE_OPERAND (base, 0);
1868 offset = fold_convert (sizetype,
1869 int_const_binop (PLUS_EXPR, offset, offset2, 1));
1872 if (TREE_CODE (base) == ADDR_EXPR)
1874 tree base_addr = base;
1876 /* Strip the ADDR_EXPR. */
1877 base = TREE_OPERAND (base, 0);
1879 /* Fold away CONST_DECL to its value, if the type is scalar. */
1880 if (TREE_CODE (base) == CONST_DECL
1881 && ccp_decl_initial_min_invariant (DECL_INITIAL (base)))
1882 return DECL_INITIAL (base);
1884 /* Try folding *(&B+O) to B.X. */
1885 t = maybe_fold_offset_to_reference (base_addr, offset,
1889 TREE_THIS_VOLATILE (t) = volatile_p;
1895 /* We can get here for out-of-range string constant accesses,
1896 such as "_"[3]. Bail out of the entire substitution search
1897 and arrange for the entire statement to be replaced by a
1898 call to __builtin_trap. In all likelihood this will all be
1899 constant-folded away, but in the meantime we can't leave with
1900 something that get_expr_operands can't understand. */
1904 if (TREE_CODE (t) == ADDR_EXPR
1905 && TREE_CODE (TREE_OPERAND (t, 0)) == STRING_CST)
1907 /* FIXME: Except that this causes problems elsewhere with dead
1908 code not being deleted, and we die in the rtl expanders
1909 because we failed to remove some ssa_name. In the meantime,
1910 just return zero. */
1911 /* FIXME2: This condition should be signaled by
1912 fold_read_from_constant_string directly, rather than
1913 re-checking for it here. */
1914 return integer_zero_node;
1917 /* Try folding *(B+O) to B->X. Still an improvement. */
1918 if (POINTER_TYPE_P (TREE_TYPE (base)))
1920 t = maybe_fold_offset_to_reference (base, offset,
1927 /* Otherwise we had an offset that we could not simplify. */
1932 /* A subroutine of fold_stmt_r. EXPR is a POINTER_PLUS_EXPR.
1934 A quaint feature extant in our address arithmetic is that there
1935 can be hidden type changes here. The type of the result need
1936 not be the same as the type of the input pointer.
1938 What we're after here is an expression of the form
1939 (T *)(&array + const)
1940 where the cast doesn't actually exist, but is implicit in the
1941 type of the POINTER_PLUS_EXPR. We'd like to turn this into
1943 which may be able to propagate further. */
1946 maybe_fold_stmt_addition (tree expr)
1948 tree op0 = TREE_OPERAND (expr, 0);
1949 tree op1 = TREE_OPERAND (expr, 1);
1950 tree ptr_type = TREE_TYPE (expr);
1954 gcc_assert (TREE_CODE (expr) == POINTER_PLUS_EXPR);
1956 /* It had better be a constant. */
1957 if (TREE_CODE (op1) != INTEGER_CST)
1959 /* The first operand should be an ADDR_EXPR. */
1960 if (TREE_CODE (op0) != ADDR_EXPR)
1962 op0 = TREE_OPERAND (op0, 0);
1964 /* If the first operand is an ARRAY_REF, expand it so that we can fold
1965 the offset into it. */
1966 while (TREE_CODE (op0) == ARRAY_REF)
1968 tree array_obj = TREE_OPERAND (op0, 0);
1969 tree array_idx = TREE_OPERAND (op0, 1);
1970 tree elt_type = TREE_TYPE (op0);
1971 tree elt_size = TYPE_SIZE_UNIT (elt_type);
1974 if (TREE_CODE (array_idx) != INTEGER_CST)
1976 if (TREE_CODE (elt_size) != INTEGER_CST)
1979 /* Un-bias the index by the min index of the array type. */
1980 min_idx = TYPE_DOMAIN (TREE_TYPE (array_obj));
1983 min_idx = TYPE_MIN_VALUE (min_idx);
1986 if (TREE_CODE (min_idx) != INTEGER_CST)
1989 array_idx = fold_convert (TREE_TYPE (min_idx), array_idx);
1990 if (!integer_zerop (min_idx))
1991 array_idx = int_const_binop (MINUS_EXPR, array_idx,
1996 /* Convert the index to a byte offset. */
1997 array_idx = fold_convert (sizetype, array_idx);
1998 array_idx = int_const_binop (MULT_EXPR, array_idx, elt_size, 0);
2000 /* Update the operands for the next round, or for folding. */
2001 op1 = int_const_binop (PLUS_EXPR,
2006 ptd_type = TREE_TYPE (ptr_type);
2008 /* At which point we can try some of the same things as for indirects. */
2009 t = maybe_fold_offset_to_array_ref (op0, op1, ptd_type);
2011 t = maybe_fold_offset_to_component_ref (TREE_TYPE (op0), op0, op1,
2014 t = build1 (ADDR_EXPR, ptr_type, t);
2019 /* For passing state through walk_tree into fold_stmt_r and its
2022 struct fold_stmt_r_data
2026 bool *inside_addr_expr_p;
2029 /* Subroutine of fold_stmt called via walk_tree. We perform several
2030 simplifications of EXPR_P, mostly having to do with pointer arithmetic. */
2033 fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data)
2035 struct fold_stmt_r_data *fold_stmt_r_data = (struct fold_stmt_r_data *) data;
2036 bool *inside_addr_expr_p = fold_stmt_r_data->inside_addr_expr_p;
2037 bool *changed_p = fold_stmt_r_data->changed_p;
2038 tree expr = *expr_p, t;
2040 /* ??? It'd be nice if walk_tree had a pre-order option. */
2041 switch (TREE_CODE (expr))
2044 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2049 t = maybe_fold_stmt_indirect (expr, TREE_OPERAND (expr, 0),
2054 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2059 if (POINTER_TYPE_P (TREE_TYPE (expr))
2060 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0)))
2061 && (t = maybe_fold_offset_to_reference
2062 (TREE_OPERAND (expr, 0),
2064 TREE_TYPE (TREE_TYPE (expr)))))
2065 t = build_fold_addr_expr_with_type (t, TREE_TYPE (expr));
2068 /* ??? Could handle more ARRAY_REFs here, as a variant of INDIRECT_REF.
2069 We'd only want to bother decomposing an existing ARRAY_REF if
2070 the base array is found to have another offset contained within.
2071 Otherwise we'd be wasting time. */
2073 /* If we are not processing expressions found within an
2074 ADDR_EXPR, then we can fold constant array references. */
2075 if (!*inside_addr_expr_p)
2076 t = fold_read_from_constant_string (expr);
2082 *inside_addr_expr_p = true;
2083 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2084 *inside_addr_expr_p = false;
2089 /* Set TREE_INVARIANT properly so that the value is properly
2090 considered constant, and so gets propagated as expected. */
2092 recompute_tree_invariant_for_addr_expr (expr);
2095 case POINTER_PLUS_EXPR:
2096 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2099 t = walk_tree (&TREE_OPERAND (expr, 1), fold_stmt_r, data, NULL);
2104 t = maybe_fold_stmt_addition (expr);
2108 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2113 /* Make sure the FIELD_DECL is actually a field in the type on the lhs.
2114 We've already checked that the records are compatible, so we should
2115 come up with a set of compatible fields. */
2117 tree expr_record = TREE_TYPE (TREE_OPERAND (expr, 0));
2118 tree expr_field = TREE_OPERAND (expr, 1);
2120 if (DECL_FIELD_CONTEXT (expr_field) != TYPE_MAIN_VARIANT (expr_record))
2122 expr_field = find_compatible_field (expr_record, expr_field);
2123 TREE_OPERAND (expr, 1) = expr_field;
2128 case TARGET_MEM_REF:
2129 t = maybe_fold_tmr (expr);
2133 if (COMPARISON_CLASS_P (TREE_OPERAND (expr, 0)))
2135 tree op0 = TREE_OPERAND (expr, 0);
2139 fold_defer_overflow_warnings ();
2140 tem = fold_binary (TREE_CODE (op0), TREE_TYPE (op0),
2141 TREE_OPERAND (op0, 0),
2142 TREE_OPERAND (op0, 1));
2143 set = tem && set_rhs (expr_p, tem);
2144 fold_undefer_overflow_warnings (set, fold_stmt_r_data->stmt, 0);
2167 /* Return the string length, maximum string length or maximum value of
2169 If ARG is an SSA name variable, follow its use-def chains. If LENGTH
2170 is not NULL and, for TYPE == 0, its value is not equal to the length
2171 we determine or if we are unable to determine the length or value,
2172 return false. VISITED is a bitmap of visited variables.
2173 TYPE is 0 if string length should be returned, 1 for maximum string
2174 length and 2 for maximum value ARG can have. */
2177 get_maxval_strlen (tree arg, tree *length, bitmap visited, int type)
2179 tree var, def_stmt, val;
2181 if (TREE_CODE (arg) != SSA_NAME)
2183 if (TREE_CODE (arg) == COND_EXPR)
2184 return get_maxval_strlen (COND_EXPR_THEN (arg), length, visited, type)
2185 && get_maxval_strlen (COND_EXPR_ELSE (arg), length, visited, type);
2190 if (TREE_CODE (val) != INTEGER_CST
2191 || tree_int_cst_sgn (val) < 0)
2195 val = c_strlen (arg, 1);
2203 if (TREE_CODE (*length) != INTEGER_CST
2204 || TREE_CODE (val) != INTEGER_CST)
2207 if (tree_int_cst_lt (*length, val))
2211 else if (simple_cst_equal (val, *length) != 1)
2219 /* If we were already here, break the infinite cycle. */
2220 if (bitmap_bit_p (visited, SSA_NAME_VERSION (arg)))
2222 bitmap_set_bit (visited, SSA_NAME_VERSION (arg));
2225 def_stmt = SSA_NAME_DEF_STMT (var);
2227 switch (TREE_CODE (def_stmt))
2229 case GIMPLE_MODIFY_STMT:
2233 /* The RHS of the statement defining VAR must either have a
2234 constant length or come from another SSA_NAME with a constant
2236 rhs = GIMPLE_STMT_OPERAND (def_stmt, 1);
2238 return get_maxval_strlen (rhs, length, visited, type);
2243 /* All the arguments of the PHI node must have the same constant
2247 for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++)
2249 tree arg = PHI_ARG_DEF (def_stmt, i);
2251 /* If this PHI has itself as an argument, we cannot
2252 determine the string length of this argument. However,
2253 if we can find a constant string length for the other
2254 PHI args then we can still be sure that this is a
2255 constant string length. So be optimistic and just
2256 continue with the next argument. */
2257 if (arg == PHI_RESULT (def_stmt))
2260 if (!get_maxval_strlen (arg, length, visited, type))
2276 /* Fold builtin call FN in statement STMT. If it cannot be folded into a
2277 constant, return NULL_TREE. Otherwise, return its constant value. */
2280 ccp_fold_builtin (tree stmt, tree fn)
2282 tree result, val[3];
2284 int arg_mask, i, type;
2287 call_expr_arg_iterator iter;
2290 ignore = TREE_CODE (stmt) != GIMPLE_MODIFY_STMT;
2292 /* First try the generic builtin folder. If that succeeds, return the
2294 result = fold_call_expr (fn, ignore);
2298 STRIP_NOPS (result);
2302 /* Ignore MD builtins. */
2303 callee = get_callee_fndecl (fn);
2304 if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_MD)
2307 /* If the builtin could not be folded, and it has no argument list,
2309 nargs = call_expr_nargs (fn);
2313 /* Limit the work only for builtins we know how to simplify. */
2314 switch (DECL_FUNCTION_CODE (callee))
2316 case BUILT_IN_STRLEN:
2317 case BUILT_IN_FPUTS:
2318 case BUILT_IN_FPUTS_UNLOCKED:
2322 case BUILT_IN_STRCPY:
2323 case BUILT_IN_STRNCPY:
2327 case BUILT_IN_MEMCPY_CHK:
2328 case BUILT_IN_MEMPCPY_CHK:
2329 case BUILT_IN_MEMMOVE_CHK:
2330 case BUILT_IN_MEMSET_CHK:
2331 case BUILT_IN_STRNCPY_CHK:
2335 case BUILT_IN_STRCPY_CHK:
2336 case BUILT_IN_STPCPY_CHK:
2340 case BUILT_IN_SNPRINTF_CHK:
2341 case BUILT_IN_VSNPRINTF_CHK:
2349 /* Try to use the dataflow information gathered by the CCP process. */
2350 visited = BITMAP_ALLOC (NULL);
2352 memset (val, 0, sizeof (val));
2353 init_call_expr_arg_iterator (fn, &iter);
2354 for (i = 0; arg_mask; i++, arg_mask >>= 1)
2356 a = next_call_expr_arg (&iter);
2359 bitmap_clear (visited);
2360 if (!get_maxval_strlen (a, &val[i], visited, type))
2365 BITMAP_FREE (visited);
2368 switch (DECL_FUNCTION_CODE (callee))
2370 case BUILT_IN_STRLEN:
2373 tree new_val = fold_convert (TREE_TYPE (fn), val[0]);
2375 /* If the result is not a valid gimple value, or not a cast
2376 of a valid gimple value, then we can not use the result. */
2377 if (is_gimple_val (new_val)
2378 || (is_gimple_cast (new_val)
2379 && is_gimple_val (TREE_OPERAND (new_val, 0))))
2384 case BUILT_IN_STRCPY:
2385 if (val[1] && is_gimple_val (val[1]) && nargs == 2)
2386 result = fold_builtin_strcpy (callee,
2387 CALL_EXPR_ARG (fn, 0),
2388 CALL_EXPR_ARG (fn, 1),
2392 case BUILT_IN_STRNCPY:
2393 if (val[1] && is_gimple_val (val[1]) && nargs == 3)
2394 result = fold_builtin_strncpy (callee,
2395 CALL_EXPR_ARG (fn, 0),
2396 CALL_EXPR_ARG (fn, 1),
2397 CALL_EXPR_ARG (fn, 2),
2401 case BUILT_IN_FPUTS:
2402 result = fold_builtin_fputs (CALL_EXPR_ARG (fn, 0),
2403 CALL_EXPR_ARG (fn, 1),
2404 TREE_CODE (stmt) != GIMPLE_MODIFY_STMT, 0,
2408 case BUILT_IN_FPUTS_UNLOCKED:
2409 result = fold_builtin_fputs (CALL_EXPR_ARG (fn, 0),
2410 CALL_EXPR_ARG (fn, 1),
2411 TREE_CODE (stmt) != GIMPLE_MODIFY_STMT, 1,
2415 case BUILT_IN_MEMCPY_CHK:
2416 case BUILT_IN_MEMPCPY_CHK:
2417 case BUILT_IN_MEMMOVE_CHK:
2418 case BUILT_IN_MEMSET_CHK:
2419 if (val[2] && is_gimple_val (val[2]))
2420 result = fold_builtin_memory_chk (callee,
2421 CALL_EXPR_ARG (fn, 0),
2422 CALL_EXPR_ARG (fn, 1),
2423 CALL_EXPR_ARG (fn, 2),
2424 CALL_EXPR_ARG (fn, 3),
2426 DECL_FUNCTION_CODE (callee));
2429 case BUILT_IN_STRCPY_CHK:
2430 case BUILT_IN_STPCPY_CHK:
2431 if (val[1] && is_gimple_val (val[1]))
2432 result = fold_builtin_stxcpy_chk (callee,
2433 CALL_EXPR_ARG (fn, 0),
2434 CALL_EXPR_ARG (fn, 1),
2435 CALL_EXPR_ARG (fn, 2),
2437 DECL_FUNCTION_CODE (callee));
2440 case BUILT_IN_STRNCPY_CHK:
2441 if (val[2] && is_gimple_val (val[2]))
2442 result = fold_builtin_strncpy_chk (CALL_EXPR_ARG (fn, 0),
2443 CALL_EXPR_ARG (fn, 1),
2444 CALL_EXPR_ARG (fn, 2),
2445 CALL_EXPR_ARG (fn, 3),
2449 case BUILT_IN_SNPRINTF_CHK:
2450 case BUILT_IN_VSNPRINTF_CHK:
2451 if (val[1] && is_gimple_val (val[1]))
2452 result = fold_builtin_snprintf_chk (fn, val[1],
2453 DECL_FUNCTION_CODE (callee));
2460 if (result && ignore)
2461 result = fold_ignored_result (result);
2466 /* Fold the statement pointed to by STMT_P. In some cases, this function may
2467 replace the whole statement with a new one. Returns true iff folding
2468 makes any changes. */
2471 fold_stmt (tree *stmt_p)
2473 tree rhs, result, stmt;
2474 struct fold_stmt_r_data fold_stmt_r_data;
2475 bool changed = false;
2476 bool inside_addr_expr = false;
2480 fold_stmt_r_data.stmt = stmt;
2481 fold_stmt_r_data.changed_p = &changed;
2482 fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr;
2484 /* If we replaced constants and the statement makes pointer dereferences,
2485 then we may need to fold instances of *&VAR into VAR, etc. */
2486 if (walk_tree (stmt_p, fold_stmt_r, &fold_stmt_r_data, NULL))
2488 *stmt_p = build_call_expr (implicit_built_in_decls[BUILT_IN_TRAP], 0);
2492 rhs = get_rhs (stmt);
2497 if (TREE_CODE (rhs) == CALL_EXPR)
2501 /* Check for builtins that CCP can handle using information not
2502 available in the generic fold routines. */
2503 callee = get_callee_fndecl (rhs);
2504 if (callee && DECL_BUILT_IN (callee))
2505 result = ccp_fold_builtin (stmt, rhs);
2508 /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve
2509 here are when we've propagated the address of a decl into the
2511 /* ??? Should perhaps do this in fold proper. However, doing it
2512 there requires that we create a new CALL_EXPR, and that requires
2513 copying EH region info to the new node. Easier to just do it
2514 here where we can just smash the call operand. Also
2515 CALL_EXPR_RETURN_SLOT_OPT needs to be handled correctly and
2516 copied, fold_call_expr does not have not information. */
2517 callee = CALL_EXPR_FN (rhs);
2518 if (TREE_CODE (callee) == OBJ_TYPE_REF
2519 && lang_hooks.fold_obj_type_ref
2520 && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee)) == ADDR_EXPR
2521 && DECL_P (TREE_OPERAND
2522 (OBJ_TYPE_REF_OBJECT (callee), 0)))
2526 /* ??? Caution: Broken ADDR_EXPR semantics means that
2527 looking at the type of the operand of the addr_expr
2528 can yield an array type. See silly exception in
2529 check_pointer_types_r. */
2531 t = TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee)));
2532 t = lang_hooks.fold_obj_type_ref (callee, t);
2535 CALL_EXPR_FN (rhs) = t;
2541 else if (TREE_CODE (rhs) == COND_EXPR)
2543 tree temp = fold (COND_EXPR_COND (rhs));
2544 if (temp != COND_EXPR_COND (rhs))
2545 result = fold_build3 (COND_EXPR, TREE_TYPE (rhs), temp,
2546 COND_EXPR_THEN (rhs), COND_EXPR_ELSE (rhs));
2549 /* If we couldn't fold the RHS, hand over to the generic fold routines. */
2550 if (result == NULL_TREE)
2551 result = fold (rhs);
2553 /* Strip away useless type conversions. Both the NON_LVALUE_EXPR that
2554 may have been added by fold, and "useless" type conversions that might
2555 now be apparent due to propagation. */
2556 STRIP_USELESS_TYPE_CONVERSION (result);
2559 changed |= set_rhs (stmt_p, result);
2564 /* Perform the minimal folding on statement STMT. Only operations like
2565 *&x created by constant propagation are handled. The statement cannot
2566 be replaced with a new one. */
2569 fold_stmt_inplace (tree stmt)
2571 tree old_stmt = stmt, rhs, new_rhs;
2572 struct fold_stmt_r_data fold_stmt_r_data;
2573 bool changed = false;
2574 bool inside_addr_expr = false;
2576 fold_stmt_r_data.stmt = stmt;
2577 fold_stmt_r_data.changed_p = &changed;
2578 fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr;
2580 walk_tree (&stmt, fold_stmt_r, &fold_stmt_r_data, NULL);
2581 gcc_assert (stmt == old_stmt);
2583 rhs = get_rhs (stmt);
2584 if (!rhs || rhs == stmt)
2587 new_rhs = fold (rhs);
2588 STRIP_USELESS_TYPE_CONVERSION (new_rhs);
2592 changed |= set_rhs (&stmt, new_rhs);
2593 gcc_assert (stmt == old_stmt);
2598 /* Convert EXPR into a GIMPLE value suitable for substitution on the
2599 RHS of an assignment. Insert the necessary statements before
2601 When IGNORE is set, don't worry about the return value. */
2604 convert_to_gimple_builtin (block_stmt_iterator *si_p, tree expr, bool ignore)
2606 tree_stmt_iterator ti;
2607 tree stmt = bsi_stmt (*si_p);
2608 tree tmp, stmts = NULL;
2610 push_gimplify_context ();
2613 tmp = build_empty_stmt ();
2614 gimplify_and_add (expr, &stmts);
2617 tmp = get_initialized_tmp_var (expr, &stmts, NULL);
2618 pop_gimplify_context (NULL);
2620 if (EXPR_HAS_LOCATION (stmt))
2621 annotate_all_with_locus (&stmts, EXPR_LOCATION (stmt));
2623 /* The replacement can expose previously unreferenced variables. */
2624 for (ti = tsi_start (stmts); !tsi_end_p (ti); tsi_next (&ti))
2626 tree new_stmt = tsi_stmt (ti);
2627 find_new_referenced_vars (tsi_stmt_ptr (ti));
2628 bsi_insert_before (si_p, new_stmt, BSI_NEW_STMT);
2629 mark_symbols_for_renaming (new_stmt);
2637 /* A simple pass that attempts to fold all builtin functions. This pass
2638 is run after we've propagated as many constants as we can. */
2641 execute_fold_all_builtins (void)
2643 bool cfg_changed = false;
2647 block_stmt_iterator i;
2648 for (i = bsi_start (bb); !bsi_end_p (i); )
2650 tree *stmtp = bsi_stmt_ptr (i);
2651 tree old_stmt = *stmtp;
2652 tree call = get_rhs (*stmtp);
2653 tree callee, result;
2654 enum built_in_function fcode;
2656 if (!call || TREE_CODE (call) != CALL_EXPR)
2661 callee = get_callee_fndecl (call);
2662 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
2667 fcode = DECL_FUNCTION_CODE (callee);
2669 result = ccp_fold_builtin (*stmtp, call);
2671 switch (DECL_FUNCTION_CODE (callee))
2673 case BUILT_IN_CONSTANT_P:
2674 /* Resolve __builtin_constant_p. If it hasn't been
2675 folded to integer_one_node by now, it's fairly
2676 certain that the value simply isn't constant. */
2677 result = integer_zero_node;
2685 if (dump_file && (dump_flags & TDF_DETAILS))
2687 fprintf (dump_file, "Simplified\n ");
2688 print_generic_stmt (dump_file, *stmtp, dump_flags);
2691 push_stmt_changes (stmtp);
2693 if (!set_rhs (stmtp, result))
2695 result = convert_to_gimple_builtin (&i, result,
2696 TREE_CODE (old_stmt)
2697 != GIMPLE_MODIFY_STMT);
2700 bool ok = set_rhs (stmtp, result);
2705 pop_stmt_changes (stmtp);
2707 if (maybe_clean_or_replace_eh_stmt (old_stmt, *stmtp)
2708 && tree_purge_dead_eh_edges (bb))
2711 if (dump_file && (dump_flags & TDF_DETAILS))
2713 fprintf (dump_file, "to\n ");
2714 print_generic_stmt (dump_file, *stmtp, dump_flags);
2715 fprintf (dump_file, "\n");
2718 /* Retry the same statement if it changed into another
2719 builtin, there might be new opportunities now. */
2720 call = get_rhs (*stmtp);
2721 if (!call || TREE_CODE (call) != CALL_EXPR)
2726 callee = get_callee_fndecl (call);
2728 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
2729 || DECL_FUNCTION_CODE (callee) == fcode)
2734 /* Delete unreachable blocks. */
2735 return cfg_changed ? TODO_cleanup_cfg : 0;
2739 struct tree_opt_pass pass_fold_builtins =
2743 execute_fold_all_builtins, /* execute */
2746 0, /* static_pass_number */
2748 PROP_cfg | PROP_ssa, /* properties_required */
2749 0, /* properties_provided */
2750 0, /* properties_destroyed */
2751 0, /* todo_flags_start */
2754 | TODO_update_ssa, /* todo_flags_finish */