1 /* Conditional constant propagation pass for the GNU compiler.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
3 Free Software Foundation, Inc.
4 Adapted from original RTL SSA-CCP by Daniel Berlin <dberlin@dberlin.org>
5 Adapted to GIMPLE trees by Diego Novillo <dnovillo@redhat.com>
7 This file is part of GCC.
9 GCC is free software; you can redistribute it and/or modify it
10 under the terms of the GNU General Public License as published by the
11 Free Software Foundation; either version 3, or (at your option) any
14 GCC is distributed in the hope that it will be useful, but WITHOUT
15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
16 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
19 You should have received a copy of the GNU General Public License
20 along with GCC; see the file COPYING3. If not see
21 <http://www.gnu.org/licenses/>. */
23 /* Conditional constant propagation (CCP) is based on the SSA
24 propagation engine (tree-ssa-propagate.c). Constant assignments of
25 the form VAR = CST are propagated from the assignments into uses of
26 VAR, which in turn may generate new constants. The simulation uses
27 a four level lattice to keep track of constant values associated
28 with SSA names. Given an SSA name V_i, it may take one of the
31 UNINITIALIZED -> the initial state of the value. This value
32 is replaced with a correct initial value
33 the first time the value is used, so the
34 rest of the pass does not need to care about
35 it. Using this value simplifies initialization
36 of the pass, and prevents us from needlessly
37 scanning statements that are never reached.
39 UNDEFINED -> V_i is a local variable whose definition
40 has not been processed yet. Therefore we
41 don't yet know if its value is a constant
44 CONSTANT -> V_i has been found to hold a constant
47 VARYING -> V_i cannot take a constant value, or if it
48 does, it is not possible to determine it
51 The core of SSA-CCP is in ccp_visit_stmt and ccp_visit_phi_node:
53 1- In ccp_visit_stmt, we are interested in assignments whose RHS
54 evaluates into a constant and conditional jumps whose predicate
55 evaluates into a boolean true or false. When an assignment of
56 the form V_i = CONST is found, V_i's lattice value is set to
57 CONSTANT and CONST is associated with it. This causes the
58 propagation engine to add all the SSA edges coming out the
59 assignment into the worklists, so that statements that use V_i
62 If the statement is a conditional with a constant predicate, we
63 mark the outgoing edges as executable or not executable
64 depending on the predicate's value. This is then used when
65 visiting PHI nodes to know when a PHI argument can be ignored.
68 2- In ccp_visit_phi_node, if all the PHI arguments evaluate to the
69 same constant C, then the LHS of the PHI is set to C. This
70 evaluation is known as the "meet operation". Since one of the
71 goals of this evaluation is to optimistically return constant
72 values as often as possible, it uses two main short cuts:
74 - If an argument is flowing in through a non-executable edge, it
75 is ignored. This is useful in cases like this:
81 a_11 = PHI (a_9, a_10)
83 If PRED is known to always evaluate to false, then we can
84 assume that a_11 will always take its value from a_10, meaning
85 that instead of consider it VARYING (a_9 and a_10 have
86 different values), we can consider it CONSTANT 100.
88 - If an argument has an UNDEFINED value, then it does not affect
89 the outcome of the meet operation. If a variable V_i has an
90 UNDEFINED value, it means that either its defining statement
91 hasn't been visited yet or V_i has no defining statement, in
92 which case the original symbol 'V' is being used
93 uninitialized. Since 'V' is a local variable, the compiler
94 may assume any initial value for it.
97 After propagation, every variable V_i that ends up with a lattice
98 value of CONSTANT will have the associated constant value in the
99 array CONST_VAL[i].VALUE. That is fed into substitute_and_fold for
100 final substitution and folding.
103 Constant propagation in stores and loads (STORE-CCP)
104 ----------------------------------------------------
106 While CCP has all the logic to propagate constants in GIMPLE
107 registers, it is missing the ability to associate constants with
108 stores and loads (i.e., pointer dereferences, structures and
109 global/aliased variables). We don't keep loads and stores in
110 SSA, but we do build a factored use-def web for them (in the
113 For instance, consider the following code fragment:
132 We should be able to deduce that the predicate 'a.a != B' is always
133 false. To achieve this, we associate constant values to the SSA
134 names in the VDEF operands for each store. Additionally,
135 since we also glob partial loads/stores with the base symbol, we
136 also keep track of the memory reference where the constant value
137 was stored (in the MEM_REF field of PROP_VALUE_T). For instance,
145 In the example above, CCP will associate value '2' with 'a_5', but
146 it would be wrong to replace the load from 'a.b' with '2', because
147 '2' had been stored into a.a.
149 Note that the initial value of virtual operands is VARYING, not
150 UNDEFINED. Consider, for instance global variables:
158 # A_5 = PHI (A_4, A_2);
166 The value of A_2 cannot be assumed to be UNDEFINED, as it may have
167 been defined outside of foo. If we were to assume it UNDEFINED, we
168 would erroneously optimize the above into 'return 3;'.
170 Though STORE-CCP is not too expensive, it does have to do more work
171 than regular CCP, so it is only enabled at -O2. Both regular CCP
172 and STORE-CCP use the exact same algorithm. The only distinction
173 is that when doing STORE-CCP, the boolean variable DO_STORE_CCP is
174 set to true. This affects the evaluation of statements and PHI
179 Constant propagation with conditional branches,
180 Wegman and Zadeck, ACM TOPLAS 13(2):181-210.
182 Building an Optimizing Compiler,
183 Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9.
185 Advanced Compiler Design and Implementation,
186 Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */
190 #include "coretypes.h"
197 #include "basic-block.h"
200 #include "function.h"
201 #include "diagnostic.h"
203 #include "tree-dump.h"
204 #include "tree-flow.h"
205 #include "tree-pass.h"
206 #include "tree-ssa-propagate.h"
207 #include "langhooks.h"
212 /* Possible lattice values. */
221 /* Array of propagated constant values. After propagation,
222 CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If
223 the constant is held in an SSA name representing a memory store
224 (i.e., a VDEF), CONST_VAL[I].MEM_REF will contain the actual
225 memory reference used to store (i.e., the LHS of the assignment
227 static prop_value_t *const_val;
229 /* True if we are also propagating constants in stores and loads. */
230 static bool do_store_ccp;
232 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */
235 dump_lattice_value (FILE *outf, const char *prefix, prop_value_t val)
237 switch (val.lattice_val)
240 fprintf (outf, "%sUNINITIALIZED", prefix);
243 fprintf (outf, "%sUNDEFINED", prefix);
246 fprintf (outf, "%sVARYING", prefix);
249 fprintf (outf, "%sCONSTANT ", prefix);
250 print_generic_expr (outf, val.value, dump_flags);
258 /* Print lattice value VAL to stderr. */
260 void debug_lattice_value (prop_value_t val);
263 debug_lattice_value (prop_value_t val)
265 dump_lattice_value (stderr, "", val);
266 fprintf (stderr, "\n");
270 /* If SYM is a constant variable with known value, return the value.
271 NULL_TREE is returned otherwise. */
274 get_symbol_constant_value (tree sym)
276 if (TREE_STATIC (sym)
277 && TREE_READONLY (sym)
280 tree val = DECL_INITIAL (sym);
282 && is_gimple_min_invariant (val))
284 /* Variables declared 'const' without an initializer
285 have zero as the intializer if they may not be
286 overridden at link or run time. */
288 && targetm.binds_local_p (sym)
289 && (INTEGRAL_TYPE_P (TREE_TYPE (sym))
290 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (sym))))
291 return fold_convert (TREE_TYPE (sym), integer_zero_node);
297 /* Compute a default value for variable VAR and store it in the
298 CONST_VAL array. The following rules are used to get default
301 1- Global and static variables that are declared constant are
304 2- Any other value is considered UNDEFINED. This is useful when
305 considering PHI nodes. PHI arguments that are undefined do not
306 change the constant value of the PHI node, which allows for more
307 constants to be propagated.
309 3- If SSA_NAME_VALUE is set and it is a constant, its value is
312 4- Variables defined by statements other than assignments and PHI
313 nodes are considered VARYING.
315 5- Initial values of variables that are not GIMPLE registers are
316 considered VARYING. */
319 get_default_value (tree var)
321 tree sym = SSA_NAME_VAR (var);
322 prop_value_t val = { UNINITIALIZED, NULL_TREE, NULL_TREE };
325 if (!do_store_ccp && !is_gimple_reg (var))
327 /* Short circuit for regular CCP. We are not interested in any
328 non-register when DO_STORE_CCP is false. */
329 val.lattice_val = VARYING;
331 else if (SSA_NAME_VALUE (var)
332 && is_gimple_min_invariant (SSA_NAME_VALUE (var)))
334 val.lattice_val = CONSTANT;
335 val.value = SSA_NAME_VALUE (var);
337 else if ((cst_val = get_symbol_constant_value (sym)) != NULL_TREE)
339 /* Globals and static variables declared 'const' take their
341 val.lattice_val = CONSTANT;
347 tree stmt = SSA_NAME_DEF_STMT (var);
349 if (IS_EMPTY_STMT (stmt))
351 /* Variables defined by an empty statement are those used
352 before being initialized. If VAR is a local variable, we
353 can assume initially that it is UNDEFINED, otherwise we must
354 consider it VARYING. */
355 if (is_gimple_reg (sym) && TREE_CODE (sym) != PARM_DECL)
356 val.lattice_val = UNDEFINED;
358 val.lattice_val = VARYING;
360 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
361 || TREE_CODE (stmt) == PHI_NODE)
363 /* Any other variable defined by an assignment or a PHI node
364 is considered UNDEFINED. */
365 val.lattice_val = UNDEFINED;
369 /* Otherwise, VAR will never take on a constant value. */
370 val.lattice_val = VARYING;
378 /* Get the constant value associated with variable VAR. */
380 static inline prop_value_t *
385 if (const_val == NULL)
388 val = &const_val[SSA_NAME_VERSION (var)];
389 if (val->lattice_val == UNINITIALIZED)
390 *val = get_default_value (var);
395 /* Sets the value associated with VAR to VARYING. */
398 set_value_varying (tree var)
400 prop_value_t *val = &const_val[SSA_NAME_VERSION (var)];
402 val->lattice_val = VARYING;
403 val->value = NULL_TREE;
404 val->mem_ref = NULL_TREE;
407 /* For float types, modify the value of VAL to make ccp work correctly
408 for non-standard values (-0, NaN):
410 If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0.
411 If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED.
412 This is to fix the following problem (see PR 29921): Suppose we have
416 and we set value of y to NaN. This causes value of x to be set to NaN.
417 When we later determine that y is in fact VARYING, fold uses the fact
418 that HONOR_NANS is false, and we try to change the value of x to 0,
419 causing an ICE. With HONOR_NANS being false, the real appearance of
420 NaN would cause undefined behavior, though, so claiming that y (and x)
421 are UNDEFINED initially is correct. */
424 canonicalize_float_value (prop_value_t *val)
426 enum machine_mode mode;
430 if (val->lattice_val != CONSTANT
431 || TREE_CODE (val->value) != REAL_CST)
434 d = TREE_REAL_CST (val->value);
435 type = TREE_TYPE (val->value);
436 mode = TYPE_MODE (type);
438 if (!HONOR_SIGNED_ZEROS (mode)
439 && REAL_VALUE_MINUS_ZERO (d))
441 val->value = build_real (type, dconst0);
445 if (!HONOR_NANS (mode)
446 && REAL_VALUE_ISNAN (d))
448 val->lattice_val = UNDEFINED;
455 /* Set the value for variable VAR to NEW_VAL. Return true if the new
456 value is different from VAR's previous value. */
459 set_lattice_value (tree var, prop_value_t new_val)
461 prop_value_t *old_val = get_value (var);
463 canonicalize_float_value (&new_val);
465 /* Lattice transitions must always be monotonically increasing in
466 value. If *OLD_VAL and NEW_VAL are the same, return false to
467 inform the caller that this was a non-transition. */
469 gcc_assert (old_val->lattice_val < new_val.lattice_val
470 || (old_val->lattice_val == new_val.lattice_val
471 && ((!old_val->value && !new_val.value)
472 || operand_equal_p (old_val->value, new_val.value, 0))
473 && old_val->mem_ref == new_val.mem_ref));
475 if (old_val->lattice_val != new_val.lattice_val)
477 if (dump_file && (dump_flags & TDF_DETAILS))
479 dump_lattice_value (dump_file, "Lattice value changed to ", new_val);
480 fprintf (dump_file, ". Adding SSA edges to worklist.\n");
485 gcc_assert (new_val.lattice_val != UNDEFINED);
493 /* Return the likely CCP lattice value for STMT.
495 If STMT has no operands, then return CONSTANT.
497 Else if undefinedness of operands of STMT cause its value to be
498 undefined, then return UNDEFINED.
500 Else if any operands of STMT are constants, then return CONSTANT.
502 Else return VARYING. */
505 likely_value (tree stmt)
507 bool has_constant_operand, has_undefined_operand, all_undefined_operands;
512 ann = stmt_ann (stmt);
514 /* If the statement has volatile operands, it won't fold to a
516 if (ann->has_volatile_ops)
519 /* If we are not doing store-ccp, statements with loads
520 and/or stores will never fold into a constant. */
522 && !ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
526 /* A CALL_EXPR is assumed to be varying. NOTE: This may be overly
527 conservative, in the presence of const and pure calls. */
528 if (get_call_expr_in (stmt) != NULL_TREE)
531 /* Anything other than assignments and conditional jumps are not
532 interesting for CCP. */
533 if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT
534 && !(TREE_CODE (stmt) == RETURN_EXPR && get_rhs (stmt) != NULL_TREE)
535 && TREE_CODE (stmt) != COND_EXPR
536 && TREE_CODE (stmt) != SWITCH_EXPR)
539 if (is_gimple_min_invariant (get_rhs (stmt)))
542 has_constant_operand = false;
543 has_undefined_operand = false;
544 all_undefined_operands = true;
545 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
547 prop_value_t *val = get_value (use);
549 if (val->lattice_val == UNDEFINED)
550 has_undefined_operand = true;
552 all_undefined_operands = false;
554 if (val->lattice_val == CONSTANT)
555 has_constant_operand = true;
558 /* If the operation combines operands like COMPLEX_EXPR make sure to
559 not mark the result UNDEFINED if only one part of the result is
561 if (has_undefined_operand
562 && all_undefined_operands)
564 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
565 && has_undefined_operand)
567 switch (TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)))
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 if (has_constant_operand
591 /* We do not consider virtual operands here -- load from read-only
592 memory may have only VARYING virtual operands, but still be
594 || ZERO_SSA_OPERANDS (stmt, SSA_OP_USE))
600 /* Returns true if STMT cannot be constant. */
603 surely_varying_stmt_p (tree stmt)
605 /* If the statement has operands that we cannot handle, it cannot be
607 if (stmt_ann (stmt)->has_volatile_ops)
610 if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
615 /* We can only handle simple loads and stores. */
616 if (!stmt_makes_single_load (stmt)
617 && !stmt_makes_single_store (stmt))
621 /* If it contains a call, it is varying. */
622 if (get_call_expr_in (stmt) != NULL_TREE)
625 /* Anything other than assignments and conditional jumps are not
626 interesting for CCP. */
627 if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT
628 && !(TREE_CODE (stmt) == RETURN_EXPR && get_rhs (stmt) != NULL_TREE)
629 && TREE_CODE (stmt) != COND_EXPR
630 && TREE_CODE (stmt) != SWITCH_EXPR)
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 block_stmt_iterator i;
650 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
652 tree stmt = bsi_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)
665 set_value_varying (def);
669 DONT_SIMULATE_AGAIN (stmt) = is_varying;
673 /* Now process PHI nodes. We never set DONT_SIMULATE_AGAIN on phi node,
674 since we do not know which edges are executable yet, except for
675 phi nodes for virtual operands when we do not do store ccp. */
680 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
682 if (!do_store_ccp && !is_gimple_reg (PHI_RESULT (phi)))
683 DONT_SIMULATE_AGAIN (phi) = true;
685 DONT_SIMULATE_AGAIN (phi) = false;
691 /* Do final substitution of propagated values, cleanup the flowgraph and
692 free allocated storage.
694 Return TRUE when something was optimized. */
699 /* Perform substitutions based on the known constant values. */
700 bool something_changed = substitute_and_fold (const_val, false);
704 return something_changed;;
708 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
711 any M UNDEFINED = any
712 any M VARYING = VARYING
713 Ci M Cj = Ci if (i == j)
714 Ci M Cj = VARYING if (i != j)
718 ccp_lattice_meet (prop_value_t *val1, prop_value_t *val2)
720 if (val1->lattice_val == UNDEFINED)
722 /* UNDEFINED M any = any */
725 else if (val2->lattice_val == UNDEFINED)
727 /* any M UNDEFINED = any
728 Nothing to do. VAL1 already contains the value we want. */
731 else if (val1->lattice_val == VARYING
732 || val2->lattice_val == VARYING)
734 /* any M VARYING = VARYING. */
735 val1->lattice_val = VARYING;
736 val1->value = NULL_TREE;
737 val1->mem_ref = NULL_TREE;
739 else if (val1->lattice_val == CONSTANT
740 && val2->lattice_val == CONSTANT
741 && simple_cst_equal (val1->value, val2->value) == 1
743 || (val1->mem_ref && val2->mem_ref
744 && operand_equal_p (val1->mem_ref, val2->mem_ref, 0))))
746 /* Ci M Cj = Ci if (i == j)
747 Ci M Cj = VARYING if (i != j)
749 If these two values come from memory stores, make sure that
750 they come from the same memory reference. */
751 val1->lattice_val = CONSTANT;
752 val1->value = val1->value;
753 val1->mem_ref = val1->mem_ref;
757 /* Any other combination is VARYING. */
758 val1->lattice_val = VARYING;
759 val1->value = NULL_TREE;
760 val1->mem_ref = NULL_TREE;
765 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
766 lattice values to determine PHI_NODE's lattice value. The value of a
767 PHI node is determined calling ccp_lattice_meet with all the arguments
768 of the PHI node that are incoming via executable edges. */
770 static enum ssa_prop_result
771 ccp_visit_phi_node (tree phi)
774 prop_value_t *old_val, new_val;
776 if (dump_file && (dump_flags & TDF_DETAILS))
778 fprintf (dump_file, "\nVisiting PHI node: ");
779 print_generic_expr (dump_file, phi, dump_flags);
782 old_val = get_value (PHI_RESULT (phi));
783 switch (old_val->lattice_val)
786 return SSA_PROP_VARYING;
793 new_val.lattice_val = UNDEFINED;
794 new_val.value = NULL_TREE;
795 new_val.mem_ref = NULL_TREE;
802 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
804 /* Compute the meet operator over all the PHI arguments flowing
805 through executable edges. */
806 edge e = PHI_ARG_EDGE (phi, i);
808 if (dump_file && (dump_flags & TDF_DETAILS))
811 "\n Argument #%d (%d -> %d %sexecutable)\n",
812 i, e->src->index, e->dest->index,
813 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
816 /* If the incoming edge is executable, Compute the meet operator for
817 the existing value of the PHI node and the current PHI argument. */
818 if (e->flags & EDGE_EXECUTABLE)
820 tree arg = PHI_ARG_DEF (phi, i);
821 prop_value_t arg_val;
823 if (is_gimple_min_invariant (arg))
825 arg_val.lattice_val = CONSTANT;
827 arg_val.mem_ref = NULL_TREE;
830 arg_val = *(get_value (arg));
832 ccp_lattice_meet (&new_val, &arg_val);
834 if (dump_file && (dump_flags & TDF_DETAILS))
836 fprintf (dump_file, "\t");
837 print_generic_expr (dump_file, arg, dump_flags);
838 dump_lattice_value (dump_file, "\tValue: ", arg_val);
839 fprintf (dump_file, "\n");
842 if (new_val.lattice_val == VARYING)
847 if (dump_file && (dump_flags & TDF_DETAILS))
849 dump_lattice_value (dump_file, "\n PHI node value: ", new_val);
850 fprintf (dump_file, "\n\n");
853 /* Make the transition to the new value. */
854 if (set_lattice_value (PHI_RESULT (phi), new_val))
856 if (new_val.lattice_val == VARYING)
857 return SSA_PROP_VARYING;
859 return SSA_PROP_INTERESTING;
862 return SSA_PROP_NOT_INTERESTING;
866 /* CCP specific front-end to the non-destructive constant folding
869 Attempt to simplify the RHS of STMT knowing that one or more
870 operands are constants.
872 If simplification is possible, return the simplified RHS,
873 otherwise return the original RHS. */
878 tree rhs = get_rhs (stmt);
879 enum tree_code code = TREE_CODE (rhs);
880 enum tree_code_class kind = TREE_CODE_CLASS (code);
881 tree retval = NULL_TREE;
883 if (TREE_CODE (rhs) == SSA_NAME)
885 /* If the RHS is an SSA_NAME, return its known constant value,
887 return get_value (rhs)->value;
889 else if (do_store_ccp && stmt_makes_single_load (stmt))
891 /* If the RHS is a memory load, see if the VUSEs associated with
892 it are a valid constant for that memory load. */
893 prop_value_t *val = get_value_loaded_by (stmt, const_val);
894 if (val && val->mem_ref)
896 if (operand_equal_p (val->mem_ref, rhs, 0))
899 /* If RHS is extracting REALPART_EXPR or IMAGPART_EXPR of a
900 complex type with a known constant value, return it. */
901 if ((TREE_CODE (rhs) == REALPART_EXPR
902 || TREE_CODE (rhs) == IMAGPART_EXPR)
903 && operand_equal_p (val->mem_ref, TREE_OPERAND (rhs, 0), 0))
904 return fold_build1 (TREE_CODE (rhs), TREE_TYPE (rhs), val->value);
909 /* Unary operators. Note that we know the single operand must
910 be a constant. So this should almost always return a
912 if (kind == tcc_unary)
914 /* Handle unary operators which can appear in GIMPLE form. */
915 tree op0 = TREE_OPERAND (rhs, 0);
917 /* Simplify the operand down to a constant. */
918 if (TREE_CODE (op0) == SSA_NAME)
920 prop_value_t *val = get_value (op0);
921 if (val->lattice_val == CONSTANT)
922 op0 = get_value (op0)->value;
925 /* Conversions are useless for CCP purposes if they are
926 value-preserving. Thus the restrictions that
927 useless_type_conversion_p places for pointer type conversions do
928 not apply here. Substitution later will only substitute to
930 if ((code == NOP_EXPR || code == CONVERT_EXPR)
931 && ((POINTER_TYPE_P (TREE_TYPE (rhs))
932 && POINTER_TYPE_P (TREE_TYPE (op0)))
933 || useless_type_conversion_p (TREE_TYPE (rhs), TREE_TYPE (op0))))
935 return fold_unary (code, TREE_TYPE (rhs), op0);
938 /* Binary and comparison operators. We know one or both of the
939 operands are constants. */
940 else if (kind == tcc_binary
941 || kind == tcc_comparison
942 || code == TRUTH_AND_EXPR
943 || code == TRUTH_OR_EXPR
944 || code == TRUTH_XOR_EXPR)
946 /* Handle binary and comparison operators that can appear in
948 tree op0 = TREE_OPERAND (rhs, 0);
949 tree op1 = TREE_OPERAND (rhs, 1);
951 /* Simplify the operands down to constants when appropriate. */
952 if (TREE_CODE (op0) == SSA_NAME)
954 prop_value_t *val = get_value (op0);
955 if (val->lattice_val == CONSTANT)
959 if (TREE_CODE (op1) == SSA_NAME)
961 prop_value_t *val = get_value (op1);
962 if (val->lattice_val == CONSTANT)
966 return fold_binary (code, TREE_TYPE (rhs), op0, op1);
969 else if (kind == tcc_declaration)
970 return get_symbol_constant_value (rhs);
972 else if (kind == tcc_reference)
973 return fold_const_aggregate_ref (rhs);
975 /* We may be able to fold away calls to builtin functions if their
976 arguments are constants. */
977 else if (code == CALL_EXPR
978 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
979 && TREE_CODE (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)) == FUNCTION_DECL
980 && DECL_BUILT_IN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
982 if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_USE))
989 /* Preserve the original values of every operand. */
990 orig = XNEWVEC (tree, NUM_SSA_OPERANDS (stmt, SSA_OP_USE));
991 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE)
994 /* Substitute operands with their values and try to fold. */
995 replace_uses_in (stmt, NULL, const_val);
996 retval = fold_call_expr (rhs, false);
998 /* Restore operands to their original form. */
1000 FOR_EACH_SSA_USE_OPERAND (var_p, stmt, iter, SSA_OP_USE)
1001 SET_USE (var_p, orig[i++]);
1008 /* If we got a simplified form, see if we need to convert its type. */
1010 return fold_convert (TREE_TYPE (rhs), retval);
1012 /* No simplification was possible. */
1017 /* Return the tree representing the element referenced by T if T is an
1018 ARRAY_REF or COMPONENT_REF into constant aggregates. Return
1019 NULL_TREE otherwise. */
1022 fold_const_aggregate_ref (tree t)
1024 prop_value_t *value;
1025 tree base, ctor, idx, field;
1026 unsigned HOST_WIDE_INT cnt;
1029 switch (TREE_CODE (t))
1032 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1033 DECL_INITIAL. If BASE is a nested reference into another
1034 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1035 the inner reference. */
1036 base = TREE_OPERAND (t, 0);
1037 switch (TREE_CODE (base))
1040 if (!TREE_READONLY (base)
1041 || TREE_CODE (TREE_TYPE (base)) != ARRAY_TYPE
1042 || !targetm.binds_local_p (base))
1045 ctor = DECL_INITIAL (base);
1050 ctor = fold_const_aggregate_ref (base);
1062 if (ctor == NULL_TREE
1063 || (TREE_CODE (ctor) != CONSTRUCTOR
1064 && TREE_CODE (ctor) != STRING_CST)
1065 || !TREE_STATIC (ctor))
1068 /* Get the index. If we have an SSA_NAME, try to resolve it
1069 with the current lattice value for the SSA_NAME. */
1070 idx = TREE_OPERAND (t, 1);
1071 switch (TREE_CODE (idx))
1074 if ((value = get_value (idx))
1075 && value->lattice_val == CONSTANT
1076 && TREE_CODE (value->value) == INTEGER_CST)
1089 /* Fold read from constant string. */
1090 if (TREE_CODE (ctor) == STRING_CST)
1092 if ((TYPE_MODE (TREE_TYPE (t))
1093 == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1094 && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1096 && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) == 1
1097 && compare_tree_int (idx, TREE_STRING_LENGTH (ctor)) < 0)
1098 return build_int_cst_type (TREE_TYPE (t),
1099 (TREE_STRING_POINTER (ctor)
1100 [TREE_INT_CST_LOW (idx)]));
1104 /* Whoo-hoo! I'll fold ya baby. Yeah! */
1105 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
1106 if (tree_int_cst_equal (cfield, idx))
1111 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1112 DECL_INITIAL. If BASE is a nested reference into another
1113 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1114 the inner reference. */
1115 base = TREE_OPERAND (t, 0);
1116 switch (TREE_CODE (base))
1119 if (!TREE_READONLY (base)
1120 || TREE_CODE (TREE_TYPE (base)) != RECORD_TYPE
1121 || !targetm.binds_local_p (base))
1124 ctor = DECL_INITIAL (base);
1129 ctor = fold_const_aggregate_ref (base);
1136 if (ctor == NULL_TREE
1137 || TREE_CODE (ctor) != CONSTRUCTOR
1138 || !TREE_STATIC (ctor))
1141 field = TREE_OPERAND (t, 1);
1143 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
1145 /* FIXME: Handle bit-fields. */
1146 && ! DECL_BIT_FIELD (cfield))
1153 tree c = fold_const_aggregate_ref (TREE_OPERAND (t, 0));
1154 if (c && TREE_CODE (c) == COMPLEX_CST)
1155 return fold_build1 (TREE_CODE (t), TREE_TYPE (t), c);
1161 tree base = TREE_OPERAND (t, 0);
1162 if (TREE_CODE (base) == SSA_NAME
1163 && (value = get_value (base))
1164 && value->lattice_val == CONSTANT
1165 && TREE_CODE (value->value) == ADDR_EXPR)
1166 return fold_const_aggregate_ref (TREE_OPERAND (value->value, 0));
1177 /* Evaluate statement STMT. */
1180 evaluate_stmt (tree stmt)
1183 tree simplified = NULL_TREE;
1184 ccp_lattice_t likelyvalue = likely_value (stmt);
1187 val.mem_ref = NULL_TREE;
1189 fold_defer_overflow_warnings ();
1191 /* If the statement is likely to have a CONSTANT result, then try
1192 to fold the statement to determine the constant value. */
1193 if (likelyvalue == CONSTANT)
1194 simplified = ccp_fold (stmt);
1195 /* If the statement is likely to have a VARYING result, then do not
1196 bother folding the statement. */
1197 else if (likelyvalue == VARYING)
1198 simplified = get_rhs (stmt);
1200 is_constant = simplified && is_gimple_min_invariant (simplified);
1202 fold_undefer_overflow_warnings (is_constant, stmt, 0);
1206 /* The statement produced a constant value. */
1207 val.lattice_val = CONSTANT;
1208 val.value = simplified;
1212 /* The statement produced a nonconstant value. If the statement
1213 had UNDEFINED operands, then the result of the statement
1214 should be UNDEFINED. Otherwise, the statement is VARYING. */
1215 if (likelyvalue == UNDEFINED)
1216 val.lattice_val = likelyvalue;
1218 val.lattice_val = VARYING;
1220 val.value = NULL_TREE;
1227 /* Visit the assignment statement STMT. Set the value of its LHS to the
1228 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
1229 creates virtual definitions, set the value of each new name to that
1230 of the RHS (if we can derive a constant out of the RHS). */
1232 static enum ssa_prop_result
1233 visit_assignment (tree stmt, tree *output_p)
1237 enum ssa_prop_result retval;
1239 lhs = GIMPLE_STMT_OPERAND (stmt, 0);
1240 rhs = GIMPLE_STMT_OPERAND (stmt, 1);
1242 if (TREE_CODE (rhs) == SSA_NAME)
1244 /* For a simple copy operation, we copy the lattice values. */
1245 prop_value_t *nval = get_value (rhs);
1248 else if (do_store_ccp && stmt_makes_single_load (stmt))
1250 /* Same as above, but the RHS is not a gimple register and yet
1251 has a known VUSE. If STMT is loading from the same memory
1252 location that created the SSA_NAMEs for the virtual operands,
1253 we can propagate the value on the RHS. */
1254 prop_value_t *nval = get_value_loaded_by (stmt, const_val);
1258 && operand_equal_p (nval->mem_ref, rhs, 0))
1261 val = evaluate_stmt (stmt);
1264 /* Evaluate the statement. */
1265 val = evaluate_stmt (stmt);
1267 retval = SSA_PROP_NOT_INTERESTING;
1269 /* Set the lattice value of the statement's output. */
1270 if (TREE_CODE (lhs) == SSA_NAME)
1272 /* If STMT is an assignment to an SSA_NAME, we only have one
1274 if (set_lattice_value (lhs, val))
1277 if (val.lattice_val == VARYING)
1278 retval = SSA_PROP_VARYING;
1280 retval = SSA_PROP_INTERESTING;
1283 else if (do_store_ccp && stmt_makes_single_store (stmt))
1285 /* Otherwise, set the names in VDEF operands to the new
1286 constant value and mark the LHS as the memory reference
1287 associated with VAL. */
1292 /* Mark VAL as stored in the LHS of this assignment. */
1293 if (val.lattice_val == CONSTANT)
1296 /* Set the value of every VDEF to VAL. */
1298 FOR_EACH_SSA_TREE_OPERAND (vdef, stmt, i, SSA_OP_VIRTUAL_DEFS)
1300 /* See PR 29801. We may have VDEFs for read-only variables
1301 (see the handling of unmodifiable variables in
1302 add_virtual_operand); do not attempt to change their value. */
1303 if (get_symbol_constant_value (SSA_NAME_VAR (vdef)) != NULL_TREE)
1306 changed |= set_lattice_value (vdef, val);
1309 /* Note that for propagation purposes, we are only interested in
1310 visiting statements that load the exact same memory reference
1311 stored here. Those statements will have the exact same list
1312 of virtual uses, so it is enough to set the output of this
1313 statement to be its first virtual definition. */
1314 *output_p = first_vdef (stmt);
1317 if (val.lattice_val == VARYING)
1318 retval = SSA_PROP_VARYING;
1320 retval = SSA_PROP_INTERESTING;
1328 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
1329 if it can determine which edge will be taken. Otherwise, return
1330 SSA_PROP_VARYING. */
1332 static enum ssa_prop_result
1333 visit_cond_stmt (tree stmt, edge *taken_edge_p)
1338 block = bb_for_stmt (stmt);
1339 val = evaluate_stmt (stmt);
1341 /* Find which edge out of the conditional block will be taken and add it
1342 to the worklist. If no single edge can be determined statically,
1343 return SSA_PROP_VARYING to feed all the outgoing edges to the
1344 propagation engine. */
1345 *taken_edge_p = val.value ? find_taken_edge (block, val.value) : 0;
1347 return SSA_PROP_INTERESTING;
1349 return SSA_PROP_VARYING;
1353 /* Evaluate statement STMT. If the statement produces an output value and
1354 its evaluation changes the lattice value of its output, return
1355 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
1358 If STMT is a conditional branch and we can determine its truth
1359 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
1360 value, return SSA_PROP_VARYING. */
1362 static enum ssa_prop_result
1363 ccp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
1368 if (dump_file && (dump_flags & TDF_DETAILS))
1370 fprintf (dump_file, "\nVisiting statement:\n");
1371 print_generic_stmt (dump_file, stmt, dump_flags);
1372 fprintf (dump_file, "\n");
1375 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
1377 /* If the statement is an assignment that produces a single
1378 output value, evaluate its RHS to see if the lattice value of
1379 its output has changed. */
1380 return visit_assignment (stmt, output_p);
1382 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
1384 /* If STMT is a conditional branch, see if we can determine
1385 which branch will be taken. */
1386 return visit_cond_stmt (stmt, taken_edge_p);
1389 /* Any other kind of statement is not interesting for constant
1390 propagation and, therefore, not worth simulating. */
1391 if (dump_file && (dump_flags & TDF_DETAILS))
1392 fprintf (dump_file, "No interesting values produced. Marked VARYING.\n");
1394 /* Definitions made by statements other than assignments to
1395 SSA_NAMEs represent unknown modifications to their outputs.
1396 Mark them VARYING. */
1397 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
1399 prop_value_t v = { VARYING, NULL_TREE, NULL_TREE };
1400 set_lattice_value (def, v);
1403 return SSA_PROP_VARYING;
1407 /* Main entry point for SSA Conditional Constant Propagation. */
1410 execute_ssa_ccp (bool store_ccp)
1412 do_store_ccp = store_ccp;
1414 ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node);
1415 if (ccp_finalize ())
1416 return (TODO_cleanup_cfg | TODO_update_ssa | TODO_remove_unused_locals);
1425 return execute_ssa_ccp (false);
1432 return flag_tree_ccp != 0;
1436 struct gimple_opt_pass pass_ccp =
1441 gate_ccp, /* gate */
1442 do_ssa_ccp, /* execute */
1445 0, /* static_pass_number */
1446 TV_TREE_CCP, /* tv_id */
1447 PROP_cfg | PROP_ssa, /* properties_required */
1448 0, /* properties_provided */
1449 0, /* properties_destroyed */
1450 0, /* todo_flags_start */
1451 TODO_dump_func | TODO_verify_ssa
1452 | TODO_verify_stmts | TODO_ggc_collect/* todo_flags_finish */
1458 do_ssa_store_ccp (void)
1460 /* If STORE-CCP is not enabled, we just run regular CCP. */
1461 return execute_ssa_ccp (flag_tree_store_ccp != 0);
1465 gate_store_ccp (void)
1467 /* STORE-CCP is enabled only with -ftree-store-ccp, but when
1468 -fno-tree-store-ccp is specified, we should run regular CCP.
1469 That's why the pass is enabled with either flag. */
1470 return flag_tree_store_ccp != 0 || flag_tree_ccp != 0;
1474 struct gimple_opt_pass pass_store_ccp =
1478 "store_ccp", /* name */
1479 gate_store_ccp, /* gate */
1480 do_ssa_store_ccp, /* execute */
1483 0, /* static_pass_number */
1484 TV_TREE_STORE_CCP, /* tv_id */
1485 PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
1486 0, /* properties_provided */
1487 0, /* properties_destroyed */
1488 0, /* todo_flags_start */
1489 TODO_dump_func | TODO_verify_ssa
1490 | TODO_verify_stmts | TODO_ggc_collect/* todo_flags_finish */
1494 /* A subroutine of fold_stmt_r. Attempts to fold *(A+O) to A[X].
1495 BASE is an array type. OFFSET is a byte displacement. ORIG_TYPE
1496 is the desired result type. */
1499 maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type,
1500 bool allow_negative_idx)
1502 tree min_idx, idx, idx_type, elt_offset = integer_zero_node;
1503 tree array_type, elt_type, elt_size;
1506 /* If BASE is an ARRAY_REF, we can pick up another offset (this time
1507 measured in units of the size of elements type) from that ARRAY_REF).
1508 We can't do anything if either is variable.
1510 The case we handle here is *(&A[N]+O). */
1511 if (TREE_CODE (base) == ARRAY_REF)
1513 tree low_bound = array_ref_low_bound (base);
1515 elt_offset = TREE_OPERAND (base, 1);
1516 if (TREE_CODE (low_bound) != INTEGER_CST
1517 || TREE_CODE (elt_offset) != INTEGER_CST)
1520 elt_offset = int_const_binop (MINUS_EXPR, elt_offset, low_bound, 0);
1521 base = TREE_OPERAND (base, 0);
1524 /* Ignore stupid user tricks of indexing non-array variables. */
1525 array_type = TREE_TYPE (base);
1526 if (TREE_CODE (array_type) != ARRAY_TYPE)
1528 elt_type = TREE_TYPE (array_type);
1529 if (!useless_type_conversion_p (orig_type, elt_type))
1532 /* Use signed size type for intermediate computation on the index. */
1533 idx_type = signed_type_for (size_type_node);
1535 /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the
1536 element type (so we can use the alignment if it's not constant).
1537 Otherwise, compute the offset as an index by using a division. If the
1538 division isn't exact, then don't do anything. */
1539 elt_size = TYPE_SIZE_UNIT (elt_type);
1542 if (integer_zerop (offset))
1544 if (TREE_CODE (elt_size) != INTEGER_CST)
1545 elt_size = size_int (TYPE_ALIGN (elt_type));
1547 idx = build_int_cst (idx_type, 0);
1551 unsigned HOST_WIDE_INT lquo, lrem;
1552 HOST_WIDE_INT hquo, hrem;
1555 /* The final array offset should be signed, so we need
1556 to sign-extend the (possibly pointer) offset here
1557 and use signed division. */
1558 soffset = double_int_sext (tree_to_double_int (offset),
1559 TYPE_PRECISION (TREE_TYPE (offset)));
1560 if (TREE_CODE (elt_size) != INTEGER_CST
1561 || div_and_round_double (TRUNC_DIV_EXPR, 0,
1562 soffset.low, soffset.high,
1563 TREE_INT_CST_LOW (elt_size),
1564 TREE_INT_CST_HIGH (elt_size),
1565 &lquo, &hquo, &lrem, &hrem)
1569 idx = build_int_cst_wide (idx_type, lquo, hquo);
1572 /* Assume the low bound is zero. If there is a domain type, get the
1573 low bound, if any, convert the index into that type, and add the
1575 min_idx = build_int_cst (idx_type, 0);
1576 domain_type = TYPE_DOMAIN (array_type);
1579 idx_type = domain_type;
1580 if (TYPE_MIN_VALUE (idx_type))
1581 min_idx = TYPE_MIN_VALUE (idx_type);
1583 min_idx = fold_convert (idx_type, min_idx);
1585 if (TREE_CODE (min_idx) != INTEGER_CST)
1588 elt_offset = fold_convert (idx_type, elt_offset);
1591 if (!integer_zerop (min_idx))
1592 idx = int_const_binop (PLUS_EXPR, idx, min_idx, 0);
1593 if (!integer_zerop (elt_offset))
1594 idx = int_const_binop (PLUS_EXPR, idx, elt_offset, 0);
1596 /* Make sure to possibly truncate late after offsetting. */
1597 idx = fold_convert (idx_type, idx);
1599 /* We don't want to construct access past array bounds. For example
1602 should not be simplified into (*c)[14] or tree-vrp will
1603 give false warnings. The same is true for
1604 struct A { long x; char d[0]; } *a;
1606 which should be not folded to &a->d[-8]. */
1608 && TYPE_MAX_VALUE (domain_type)
1609 && TREE_CODE (TYPE_MAX_VALUE (domain_type)) == INTEGER_CST)
1611 tree up_bound = TYPE_MAX_VALUE (domain_type);
1613 if (tree_int_cst_lt (up_bound, idx)
1614 /* Accesses after the end of arrays of size 0 (gcc
1615 extension) and 1 are likely intentional ("struct
1617 && compare_tree_int (up_bound, 1) > 0)
1621 && TYPE_MIN_VALUE (domain_type))
1623 if (!allow_negative_idx
1624 && TREE_CODE (TYPE_MIN_VALUE (domain_type)) == INTEGER_CST
1625 && tree_int_cst_lt (idx, TYPE_MIN_VALUE (domain_type)))
1628 else if (!allow_negative_idx
1629 && compare_tree_int (idx, 0) < 0)
1632 return build4 (ARRAY_REF, elt_type, base, idx, NULL_TREE, NULL_TREE);
1636 /* Attempt to fold *(S+O) to S.X.
1637 BASE is a record type. OFFSET is a byte displacement. ORIG_TYPE
1638 is the desired result type. */
1641 maybe_fold_offset_to_component_ref (tree record_type, tree base, tree offset,
1642 tree orig_type, bool base_is_ptr)
1644 tree f, t, field_type, tail_array_field, field_offset;
1648 if (TREE_CODE (record_type) != RECORD_TYPE
1649 && TREE_CODE (record_type) != UNION_TYPE
1650 && TREE_CODE (record_type) != QUAL_UNION_TYPE)
1653 /* Short-circuit silly cases. */
1654 if (useless_type_conversion_p (record_type, orig_type))
1657 tail_array_field = NULL_TREE;
1658 for (f = TYPE_FIELDS (record_type); f ; f = TREE_CHAIN (f))
1662 if (TREE_CODE (f) != FIELD_DECL)
1664 if (DECL_BIT_FIELD (f))
1667 if (!DECL_FIELD_OFFSET (f))
1669 field_offset = byte_position (f);
1670 if (TREE_CODE (field_offset) != INTEGER_CST)
1673 /* ??? Java creates "interesting" fields for representing base classes.
1674 They have no name, and have no context. With no context, we get into
1675 trouble with nonoverlapping_component_refs_p. Skip them. */
1676 if (!DECL_FIELD_CONTEXT (f))
1679 /* The previous array field isn't at the end. */
1680 tail_array_field = NULL_TREE;
1682 /* Check to see if this offset overlaps with the field. */
1683 cmp = tree_int_cst_compare (field_offset, offset);
1687 field_type = TREE_TYPE (f);
1689 /* Here we exactly match the offset being checked. If the types match,
1690 then we can return that field. */
1692 && useless_type_conversion_p (orig_type, field_type))
1695 base = build1 (INDIRECT_REF, record_type, base);
1696 t = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE);
1700 /* Don't care about offsets into the middle of scalars. */
1701 if (!AGGREGATE_TYPE_P (field_type))
1704 /* Check for array at the end of the struct. This is often
1705 used as for flexible array members. We should be able to
1706 turn this into an array access anyway. */
1707 if (TREE_CODE (field_type) == ARRAY_TYPE)
1708 tail_array_field = f;
1710 /* Check the end of the field against the offset. */
1711 if (!DECL_SIZE_UNIT (f)
1712 || TREE_CODE (DECL_SIZE_UNIT (f)) != INTEGER_CST)
1714 t = int_const_binop (MINUS_EXPR, offset, field_offset, 1);
1715 if (!tree_int_cst_lt (t, DECL_SIZE_UNIT (f)))
1718 /* If we matched, then set offset to the displacement into
1721 new_base = build1 (INDIRECT_REF, record_type, base);
1724 new_base = build3 (COMPONENT_REF, field_type, new_base, f, NULL_TREE);
1726 /* Recurse to possibly find the match. */
1727 ret = maybe_fold_offset_to_array_ref (new_base, t, orig_type,
1728 f == TYPE_FIELDS (record_type));
1731 ret = maybe_fold_offset_to_component_ref (field_type, new_base, t,
1737 if (!tail_array_field)
1740 f = tail_array_field;
1741 field_type = TREE_TYPE (f);
1742 offset = int_const_binop (MINUS_EXPR, offset, byte_position (f), 1);
1744 /* If we get here, we've got an aggregate field, and a possibly
1745 nonzero offset into them. Recurse and hope for a valid match. */
1747 base = build1 (INDIRECT_REF, record_type, base);
1748 base = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE);
1750 t = maybe_fold_offset_to_array_ref (base, offset, orig_type,
1751 f == TYPE_FIELDS (record_type));
1754 return maybe_fold_offset_to_component_ref (field_type, base, offset,
1758 /* Attempt to express (ORIG_TYPE)BASE+OFFSET as BASE->field_of_orig_type
1759 or BASE[index] or by combination of those.
1761 Before attempting the conversion strip off existing ADDR_EXPRs and
1762 handled component refs. */
1765 maybe_fold_offset_to_reference (tree base, tree offset, tree orig_type)
1769 bool base_is_ptr = true;
1772 if (TREE_CODE (base) == ADDR_EXPR)
1774 base_is_ptr = false;
1776 base = TREE_OPERAND (base, 0);
1778 /* Handle case where existing COMPONENT_REF pick e.g. wrong field of union,
1779 so it needs to be removed and new COMPONENT_REF constructed.
1780 The wrong COMPONENT_REF are often constructed by folding the
1781 (type *)&object within the expression (type *)&object+offset */
1782 if (handled_component_p (base) && 0)
1784 HOST_WIDE_INT sub_offset, size, maxsize;
1786 newbase = get_ref_base_and_extent (base, &sub_offset,
1788 gcc_assert (newbase);
1789 gcc_assert (!(sub_offset & (BITS_PER_UNIT - 1)));
1790 if (size == maxsize)
1794 offset = int_const_binop (PLUS_EXPR, offset,
1795 build_int_cst (TREE_TYPE (offset),
1796 sub_offset / BITS_PER_UNIT), 1);
1799 if (useless_type_conversion_p (orig_type, TREE_TYPE (base))
1800 && integer_zerop (offset))
1802 type = TREE_TYPE (base);
1807 if (!POINTER_TYPE_P (TREE_TYPE (base)))
1809 type = TREE_TYPE (TREE_TYPE (base));
1811 ret = maybe_fold_offset_to_component_ref (type, base, offset,
1812 orig_type, base_is_ptr);
1816 base = build1 (INDIRECT_REF, type, base);
1817 ret = maybe_fold_offset_to_array_ref (base, offset, orig_type, true);
1822 /* A subroutine of fold_stmt_r. Attempt to simplify *(BASE+OFFSET).
1823 Return the simplified expression, or NULL if nothing could be done. */
1826 maybe_fold_stmt_indirect (tree expr, tree base, tree offset)
1829 bool volatile_p = TREE_THIS_VOLATILE (expr);
1831 /* We may well have constructed a double-nested PLUS_EXPR via multiple
1832 substitutions. Fold that down to one. Remove NON_LVALUE_EXPRs that
1833 are sometimes added. */
1835 STRIP_TYPE_NOPS (base);
1836 TREE_OPERAND (expr, 0) = base;
1838 /* One possibility is that the address reduces to a string constant. */
1839 t = fold_read_from_constant_string (expr);
1843 /* Add in any offset from a POINTER_PLUS_EXPR. */
1844 if (TREE_CODE (base) == POINTER_PLUS_EXPR)
1848 offset2 = TREE_OPERAND (base, 1);
1849 if (TREE_CODE (offset2) != INTEGER_CST)
1851 base = TREE_OPERAND (base, 0);
1853 offset = fold_convert (sizetype,
1854 int_const_binop (PLUS_EXPR, offset, offset2, 1));
1857 if (TREE_CODE (base) == ADDR_EXPR)
1859 tree base_addr = base;
1861 /* Strip the ADDR_EXPR. */
1862 base = TREE_OPERAND (base, 0);
1864 /* Fold away CONST_DECL to its value, if the type is scalar. */
1865 if (TREE_CODE (base) == CONST_DECL
1866 && is_gimple_min_invariant (DECL_INITIAL (base)))
1867 return DECL_INITIAL (base);
1869 /* Try folding *(&B+O) to B.X. */
1870 t = maybe_fold_offset_to_reference (base_addr, offset,
1874 TREE_THIS_VOLATILE (t) = volatile_p;
1880 /* We can get here for out-of-range string constant accesses,
1881 such as "_"[3]. Bail out of the entire substitution search
1882 and arrange for the entire statement to be replaced by a
1883 call to __builtin_trap. In all likelihood this will all be
1884 constant-folded away, but in the meantime we can't leave with
1885 something that get_expr_operands can't understand. */
1889 if (TREE_CODE (t) == ADDR_EXPR
1890 && TREE_CODE (TREE_OPERAND (t, 0)) == STRING_CST)
1892 /* FIXME: Except that this causes problems elsewhere with dead
1893 code not being deleted, and we die in the rtl expanders
1894 because we failed to remove some ssa_name. In the meantime,
1895 just return zero. */
1896 /* FIXME2: This condition should be signaled by
1897 fold_read_from_constant_string directly, rather than
1898 re-checking for it here. */
1899 return integer_zero_node;
1902 /* Try folding *(B+O) to B->X. Still an improvement. */
1903 if (POINTER_TYPE_P (TREE_TYPE (base)))
1905 t = maybe_fold_offset_to_reference (base, offset,
1912 /* Otherwise we had an offset that we could not simplify. */
1917 /* A subroutine of fold_stmt_r. EXPR is a POINTER_PLUS_EXPR.
1919 A quaint feature extant in our address arithmetic is that there
1920 can be hidden type changes here. The type of the result need
1921 not be the same as the type of the input pointer.
1923 What we're after here is an expression of the form
1924 (T *)(&array + const)
1925 where the cast doesn't actually exist, but is implicit in the
1926 type of the POINTER_PLUS_EXPR. We'd like to turn this into
1928 which may be able to propagate further. */
1931 maybe_fold_stmt_addition (tree expr)
1933 tree op0 = TREE_OPERAND (expr, 0);
1934 tree op1 = TREE_OPERAND (expr, 1);
1935 tree ptr_type = TREE_TYPE (expr);
1939 gcc_assert (TREE_CODE (expr) == POINTER_PLUS_EXPR);
1941 /* It had better be a constant. */
1942 if (TREE_CODE (op1) != INTEGER_CST)
1944 /* The first operand should be an ADDR_EXPR. */
1945 if (TREE_CODE (op0) != ADDR_EXPR)
1947 op0 = TREE_OPERAND (op0, 0);
1949 /* If the first operand is an ARRAY_REF, expand it so that we can fold
1950 the offset into it. */
1951 while (TREE_CODE (op0) == ARRAY_REF)
1953 tree array_obj = TREE_OPERAND (op0, 0);
1954 tree array_idx = TREE_OPERAND (op0, 1);
1955 tree elt_type = TREE_TYPE (op0);
1956 tree elt_size = TYPE_SIZE_UNIT (elt_type);
1959 if (TREE_CODE (array_idx) != INTEGER_CST)
1961 if (TREE_CODE (elt_size) != INTEGER_CST)
1964 /* Un-bias the index by the min index of the array type. */
1965 min_idx = TYPE_DOMAIN (TREE_TYPE (array_obj));
1968 min_idx = TYPE_MIN_VALUE (min_idx);
1971 if (TREE_CODE (min_idx) != INTEGER_CST)
1974 array_idx = fold_convert (TREE_TYPE (min_idx), array_idx);
1975 if (!integer_zerop (min_idx))
1976 array_idx = int_const_binop (MINUS_EXPR, array_idx,
1981 /* Convert the index to a byte offset. */
1982 array_idx = fold_convert (sizetype, array_idx);
1983 array_idx = int_const_binop (MULT_EXPR, array_idx, elt_size, 0);
1985 /* Update the operands for the next round, or for folding. */
1986 op1 = int_const_binop (PLUS_EXPR,
1991 ptd_type = TREE_TYPE (ptr_type);
1992 /* If we want a pointer to void, reconstruct the reference from the
1993 array element type. A pointer to that can be trivially converted
1994 to void *. This happens as we fold (void *)(ptr p+ off). */
1995 if (VOID_TYPE_P (ptd_type)
1996 && TREE_CODE (TREE_TYPE (op0)) == ARRAY_TYPE)
1997 ptd_type = TREE_TYPE (TREE_TYPE (op0));
1999 /* At which point we can try some of the same things as for indirects. */
2000 t = maybe_fold_offset_to_array_ref (op0, op1, ptd_type, true);
2002 t = maybe_fold_offset_to_component_ref (TREE_TYPE (op0), op0, op1,
2005 t = build1 (ADDR_EXPR, ptr_type, t);
2010 /* For passing state through walk_tree into fold_stmt_r and its
2013 struct fold_stmt_r_data
2017 bool *inside_addr_expr_p;
2020 /* Subroutine of fold_stmt called via walk_tree. We perform several
2021 simplifications of EXPR_P, mostly having to do with pointer arithmetic. */
2024 fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data)
2026 struct fold_stmt_r_data *fold_stmt_r_data = (struct fold_stmt_r_data *) data;
2027 bool *inside_addr_expr_p = fold_stmt_r_data->inside_addr_expr_p;
2028 bool *changed_p = fold_stmt_r_data->changed_p;
2029 tree expr = *expr_p, t;
2030 bool volatile_p = TREE_THIS_VOLATILE (expr);
2032 /* ??? It'd be nice if walk_tree had a pre-order option. */
2033 switch (TREE_CODE (expr))
2036 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2041 t = maybe_fold_stmt_indirect (expr, TREE_OPERAND (expr, 0),
2044 && TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR)
2045 /* If we had a good reason for propagating the address here,
2046 make sure we end up with valid gimple. See PR34989. */
2047 t = TREE_OPERAND (TREE_OPERAND (expr, 0), 0);
2051 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2056 if (POINTER_TYPE_P (TREE_TYPE (expr))
2057 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0)))
2058 && (t = maybe_fold_offset_to_reference
2059 (TREE_OPERAND (expr, 0),
2061 TREE_TYPE (TREE_TYPE (expr)))))
2063 tree ptr_type = build_pointer_type (TREE_TYPE (t));
2064 if (!useless_type_conversion_p (TREE_TYPE (expr), ptr_type))
2066 t = build_fold_addr_expr_with_type (t, ptr_type);
2070 /* ??? Could handle more ARRAY_REFs here, as a variant of INDIRECT_REF.
2071 We'd only want to bother decomposing an existing ARRAY_REF if
2072 the base array is found to have another offset contained within.
2073 Otherwise we'd be wasting time. */
2075 /* If we are not processing expressions found within an
2076 ADDR_EXPR, then we can fold constant array references. */
2077 if (!*inside_addr_expr_p)
2078 t = fold_read_from_constant_string (expr);
2084 *inside_addr_expr_p = true;
2085 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2086 *inside_addr_expr_p = false;
2091 /* Set TREE_INVARIANT properly so that the value is properly
2092 considered constant, and so gets propagated as expected. */
2094 recompute_tree_invariant_for_addr_expr (expr);
2097 case POINTER_PLUS_EXPR:
2098 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2101 t = walk_tree (&TREE_OPERAND (expr, 1), fold_stmt_r, data, NULL);
2106 t = maybe_fold_stmt_addition (expr);
2110 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2115 /* Make sure the FIELD_DECL is actually a field in the type on the lhs.
2116 We've already checked that the records are compatible, so we should
2117 come up with a set of compatible fields. */
2119 tree expr_record = TREE_TYPE (TREE_OPERAND (expr, 0));
2120 tree expr_field = TREE_OPERAND (expr, 1);
2122 if (DECL_FIELD_CONTEXT (expr_field) != TYPE_MAIN_VARIANT (expr_record))
2124 expr_field = find_compatible_field (expr_record, expr_field);
2125 TREE_OPERAND (expr, 1) = expr_field;
2130 case TARGET_MEM_REF:
2131 t = maybe_fold_tmr (expr);
2135 if (COMPARISON_CLASS_P (TREE_OPERAND (expr, 0)))
2137 tree op0 = TREE_OPERAND (expr, 0);
2141 fold_defer_overflow_warnings ();
2142 tem = fold_binary (TREE_CODE (op0), TREE_TYPE (op0),
2143 TREE_OPERAND (op0, 0),
2144 TREE_OPERAND (op0, 1));
2145 set = tem && set_rhs (expr_p, tem);
2146 fold_undefer_overflow_warnings (set, fold_stmt_r_data->stmt, 0);
2161 /* Preserve volatileness of the original expression. */
2162 TREE_THIS_VOLATILE (t) = volatile_p;
2171 /* Return the string length, maximum string length or maximum value of
2173 If ARG is an SSA name variable, follow its use-def chains. If LENGTH
2174 is not NULL and, for TYPE == 0, its value is not equal to the length
2175 we determine or if we are unable to determine the length or value,
2176 return false. VISITED is a bitmap of visited variables.
2177 TYPE is 0 if string length should be returned, 1 for maximum string
2178 length and 2 for maximum value ARG can have. */
2181 get_maxval_strlen (tree arg, tree *length, bitmap visited, int type)
2183 tree var, def_stmt, val;
2185 if (TREE_CODE (arg) != SSA_NAME)
2187 if (TREE_CODE (arg) == COND_EXPR)
2188 return get_maxval_strlen (COND_EXPR_THEN (arg), length, visited, type)
2189 && get_maxval_strlen (COND_EXPR_ELSE (arg), length, visited, type);
2190 /* We can end up with &(*iftmp_1)[0] here as well, so handle it. */
2191 else if (TREE_CODE (arg) == ADDR_EXPR
2192 && TREE_CODE (TREE_OPERAND (arg, 0)) == ARRAY_REF
2193 && integer_zerop (TREE_OPERAND (TREE_OPERAND (arg, 0), 1)))
2195 tree aop0 = TREE_OPERAND (TREE_OPERAND (arg, 0), 0);
2196 if (TREE_CODE (aop0) == INDIRECT_REF
2197 && TREE_CODE (TREE_OPERAND (aop0, 0)) == SSA_NAME)
2198 return get_maxval_strlen (TREE_OPERAND (aop0, 0),
2199 length, visited, type);
2205 if (TREE_CODE (val) != INTEGER_CST
2206 || tree_int_cst_sgn (val) < 0)
2210 val = c_strlen (arg, 1);
2218 if (TREE_CODE (*length) != INTEGER_CST
2219 || TREE_CODE (val) != INTEGER_CST)
2222 if (tree_int_cst_lt (*length, val))
2226 else if (simple_cst_equal (val, *length) != 1)
2234 /* If we were already here, break the infinite cycle. */
2235 if (bitmap_bit_p (visited, SSA_NAME_VERSION (arg)))
2237 bitmap_set_bit (visited, SSA_NAME_VERSION (arg));
2240 def_stmt = SSA_NAME_DEF_STMT (var);
2242 switch (TREE_CODE (def_stmt))
2244 case GIMPLE_MODIFY_STMT:
2248 /* The RHS of the statement defining VAR must either have a
2249 constant length or come from another SSA_NAME with a constant
2251 rhs = GIMPLE_STMT_OPERAND (def_stmt, 1);
2253 return get_maxval_strlen (rhs, length, visited, type);
2258 /* All the arguments of the PHI node must have the same constant
2262 for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++)
2264 tree arg = PHI_ARG_DEF (def_stmt, i);
2266 /* If this PHI has itself as an argument, we cannot
2267 determine the string length of this argument. However,
2268 if we can find a constant string length for the other
2269 PHI args then we can still be sure that this is a
2270 constant string length. So be optimistic and just
2271 continue with the next argument. */
2272 if (arg == PHI_RESULT (def_stmt))
2275 if (!get_maxval_strlen (arg, length, visited, type))
2291 /* Fold builtin call FN in statement STMT. If it cannot be folded into a
2292 constant, return NULL_TREE. Otherwise, return its constant value. */
2295 ccp_fold_builtin (tree stmt, tree fn)
2297 tree result, val[3];
2299 int arg_mask, i, type;
2302 call_expr_arg_iterator iter;
2305 ignore = TREE_CODE (stmt) != GIMPLE_MODIFY_STMT;
2307 /* First try the generic builtin folder. If that succeeds, return the
2309 result = fold_call_expr (fn, ignore);
2313 STRIP_NOPS (result);
2317 /* Ignore MD builtins. */
2318 callee = get_callee_fndecl (fn);
2319 if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_MD)
2322 /* If the builtin could not be folded, and it has no argument list,
2324 nargs = call_expr_nargs (fn);
2328 /* Limit the work only for builtins we know how to simplify. */
2329 switch (DECL_FUNCTION_CODE (callee))
2331 case BUILT_IN_STRLEN:
2332 case BUILT_IN_FPUTS:
2333 case BUILT_IN_FPUTS_UNLOCKED:
2337 case BUILT_IN_STRCPY:
2338 case BUILT_IN_STRNCPY:
2342 case BUILT_IN_MEMCPY_CHK:
2343 case BUILT_IN_MEMPCPY_CHK:
2344 case BUILT_IN_MEMMOVE_CHK:
2345 case BUILT_IN_MEMSET_CHK:
2346 case BUILT_IN_STRNCPY_CHK:
2350 case BUILT_IN_STRCPY_CHK:
2351 case BUILT_IN_STPCPY_CHK:
2355 case BUILT_IN_SNPRINTF_CHK:
2356 case BUILT_IN_VSNPRINTF_CHK:
2364 /* Try to use the dataflow information gathered by the CCP process. */
2365 visited = BITMAP_ALLOC (NULL);
2367 memset (val, 0, sizeof (val));
2368 init_call_expr_arg_iterator (fn, &iter);
2369 for (i = 0; arg_mask; i++, arg_mask >>= 1)
2371 a = next_call_expr_arg (&iter);
2374 bitmap_clear (visited);
2375 if (!get_maxval_strlen (a, &val[i], visited, type))
2380 BITMAP_FREE (visited);
2383 switch (DECL_FUNCTION_CODE (callee))
2385 case BUILT_IN_STRLEN:
2388 tree new_val = fold_convert (TREE_TYPE (fn), val[0]);
2390 /* If the result is not a valid gimple value, or not a cast
2391 of a valid gimple value, then we can not use the result. */
2392 if (is_gimple_val (new_val)
2393 || (is_gimple_cast (new_val)
2394 && is_gimple_val (TREE_OPERAND (new_val, 0))))
2399 case BUILT_IN_STRCPY:
2400 if (val[1] && is_gimple_val (val[1]) && nargs == 2)
2401 result = fold_builtin_strcpy (callee,
2402 CALL_EXPR_ARG (fn, 0),
2403 CALL_EXPR_ARG (fn, 1),
2407 case BUILT_IN_STRNCPY:
2408 if (val[1] && is_gimple_val (val[1]) && nargs == 3)
2409 result = fold_builtin_strncpy (callee,
2410 CALL_EXPR_ARG (fn, 0),
2411 CALL_EXPR_ARG (fn, 1),
2412 CALL_EXPR_ARG (fn, 2),
2416 case BUILT_IN_FPUTS:
2417 result = fold_builtin_fputs (CALL_EXPR_ARG (fn, 0),
2418 CALL_EXPR_ARG (fn, 1),
2419 TREE_CODE (stmt) != GIMPLE_MODIFY_STMT, 0,
2423 case BUILT_IN_FPUTS_UNLOCKED:
2424 result = fold_builtin_fputs (CALL_EXPR_ARG (fn, 0),
2425 CALL_EXPR_ARG (fn, 1),
2426 TREE_CODE (stmt) != GIMPLE_MODIFY_STMT, 1,
2430 case BUILT_IN_MEMCPY_CHK:
2431 case BUILT_IN_MEMPCPY_CHK:
2432 case BUILT_IN_MEMMOVE_CHK:
2433 case BUILT_IN_MEMSET_CHK:
2434 if (val[2] && is_gimple_val (val[2]))
2435 result = fold_builtin_memory_chk (callee,
2436 CALL_EXPR_ARG (fn, 0),
2437 CALL_EXPR_ARG (fn, 1),
2438 CALL_EXPR_ARG (fn, 2),
2439 CALL_EXPR_ARG (fn, 3),
2441 DECL_FUNCTION_CODE (callee));
2444 case BUILT_IN_STRCPY_CHK:
2445 case BUILT_IN_STPCPY_CHK:
2446 if (val[1] && is_gimple_val (val[1]))
2447 result = fold_builtin_stxcpy_chk (callee,
2448 CALL_EXPR_ARG (fn, 0),
2449 CALL_EXPR_ARG (fn, 1),
2450 CALL_EXPR_ARG (fn, 2),
2452 DECL_FUNCTION_CODE (callee));
2455 case BUILT_IN_STRNCPY_CHK:
2456 if (val[2] && is_gimple_val (val[2]))
2457 result = fold_builtin_strncpy_chk (CALL_EXPR_ARG (fn, 0),
2458 CALL_EXPR_ARG (fn, 1),
2459 CALL_EXPR_ARG (fn, 2),
2460 CALL_EXPR_ARG (fn, 3),
2464 case BUILT_IN_SNPRINTF_CHK:
2465 case BUILT_IN_VSNPRINTF_CHK:
2466 if (val[1] && is_gimple_val (val[1]))
2467 result = fold_builtin_snprintf_chk (fn, val[1],
2468 DECL_FUNCTION_CODE (callee));
2475 if (result && ignore)
2476 result = fold_ignored_result (result);
2481 /* Fold the statement pointed to by STMT_P. In some cases, this function may
2482 replace the whole statement with a new one. Returns true iff folding
2483 makes any changes. */
2486 fold_stmt (tree *stmt_p)
2488 tree rhs, result, stmt;
2489 struct fold_stmt_r_data fold_stmt_r_data;
2490 bool changed = false;
2491 bool inside_addr_expr = false;
2495 fold_stmt_r_data.stmt = stmt;
2496 fold_stmt_r_data.changed_p = &changed;
2497 fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr;
2499 /* If we replaced constants and the statement makes pointer dereferences,
2500 then we may need to fold instances of *&VAR into VAR, etc. */
2501 if (walk_tree (stmt_p, fold_stmt_r, &fold_stmt_r_data, NULL))
2503 *stmt_p = build_call_expr (implicit_built_in_decls[BUILT_IN_TRAP], 0);
2507 rhs = get_rhs (stmt);
2512 if (TREE_CODE (rhs) == CALL_EXPR)
2516 /* Check for builtins that CCP can handle using information not
2517 available in the generic fold routines. */
2518 callee = get_callee_fndecl (rhs);
2519 if (callee && DECL_BUILT_IN (callee))
2520 result = ccp_fold_builtin (stmt, rhs);
2523 /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve
2524 here are when we've propagated the address of a decl into the
2526 /* ??? Should perhaps do this in fold proper. However, doing it
2527 there requires that we create a new CALL_EXPR, and that requires
2528 copying EH region info to the new node. Easier to just do it
2529 here where we can just smash the call operand. Also
2530 CALL_EXPR_RETURN_SLOT_OPT needs to be handled correctly and
2531 copied, fold_call_expr does not have not information. */
2532 callee = CALL_EXPR_FN (rhs);
2533 if (TREE_CODE (callee) == OBJ_TYPE_REF
2534 && lang_hooks.fold_obj_type_ref
2535 && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee)) == ADDR_EXPR
2536 && DECL_P (TREE_OPERAND
2537 (OBJ_TYPE_REF_OBJECT (callee), 0)))
2541 /* ??? Caution: Broken ADDR_EXPR semantics means that
2542 looking at the type of the operand of the addr_expr
2543 can yield an array type. See silly exception in
2544 check_pointer_types_r. */
2546 t = TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee)));
2547 t = lang_hooks.fold_obj_type_ref (callee, t);
2550 CALL_EXPR_FN (rhs) = t;
2556 else if (TREE_CODE (rhs) == COND_EXPR)
2558 tree temp = fold (COND_EXPR_COND (rhs));
2559 if (temp != COND_EXPR_COND (rhs))
2560 result = fold_build3 (COND_EXPR, TREE_TYPE (rhs), temp,
2561 COND_EXPR_THEN (rhs), COND_EXPR_ELSE (rhs));
2564 /* If we couldn't fold the RHS, hand over to the generic fold routines. */
2565 if (result == NULL_TREE)
2566 result = fold (rhs);
2568 /* Strip away useless type conversions. Both the NON_LVALUE_EXPR that
2569 may have been added by fold, and "useless" type conversions that might
2570 now be apparent due to propagation. */
2571 STRIP_USELESS_TYPE_CONVERSION (result);
2574 changed |= set_rhs (stmt_p, result);
2579 /* Perform the minimal folding on statement STMT. Only operations like
2580 *&x created by constant propagation are handled. The statement cannot
2581 be replaced with a new one. */
2584 fold_stmt_inplace (tree stmt)
2586 tree old_stmt = stmt, rhs, new_rhs;
2587 struct fold_stmt_r_data fold_stmt_r_data;
2588 bool changed = false;
2589 bool inside_addr_expr = false;
2591 fold_stmt_r_data.stmt = stmt;
2592 fold_stmt_r_data.changed_p = &changed;
2593 fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr;
2595 walk_tree (&stmt, fold_stmt_r, &fold_stmt_r_data, NULL);
2596 gcc_assert (stmt == old_stmt);
2598 rhs = get_rhs (stmt);
2599 if (!rhs || rhs == stmt)
2602 new_rhs = fold (rhs);
2603 STRIP_USELESS_TYPE_CONVERSION (new_rhs);
2607 changed |= set_rhs (&stmt, new_rhs);
2608 gcc_assert (stmt == old_stmt);
2613 /* Try to optimize out __builtin_stack_restore. Optimize it out
2614 if there is another __builtin_stack_restore in the same basic
2615 block and no calls or ASM_EXPRs are in between, or if this block's
2616 only outgoing edge is to EXIT_BLOCK and there are no calls or
2617 ASM_EXPRs after this __builtin_stack_restore. */
2620 optimize_stack_restore (basic_block bb, tree call, block_stmt_iterator i)
2622 tree stack_save, stmt, callee;
2624 if (TREE_CODE (call) != CALL_EXPR
2625 || call_expr_nargs (call) != 1
2626 || TREE_CODE (CALL_EXPR_ARG (call, 0)) != SSA_NAME
2627 || !POINTER_TYPE_P (TREE_TYPE (CALL_EXPR_ARG (call, 0))))
2630 for (bsi_next (&i); !bsi_end_p (i); bsi_next (&i))
2634 stmt = bsi_stmt (i);
2635 if (TREE_CODE (stmt) == ASM_EXPR)
2637 call = get_call_expr_in (stmt);
2641 callee = get_callee_fndecl (call);
2642 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
2645 if (DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_RESTORE)
2650 && (! single_succ_p (bb)
2651 || single_succ_edge (bb)->dest != EXIT_BLOCK_PTR))
2654 stack_save = SSA_NAME_DEF_STMT (CALL_EXPR_ARG (call, 0));
2655 if (TREE_CODE (stack_save) != GIMPLE_MODIFY_STMT
2656 || GIMPLE_STMT_OPERAND (stack_save, 0) != CALL_EXPR_ARG (call, 0)
2657 || TREE_CODE (GIMPLE_STMT_OPERAND (stack_save, 1)) != CALL_EXPR
2658 || tree_could_throw_p (stack_save)
2659 || !has_single_use (CALL_EXPR_ARG (call, 0)))
2662 callee = get_callee_fndecl (GIMPLE_STMT_OPERAND (stack_save, 1));
2664 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
2665 || DECL_FUNCTION_CODE (callee) != BUILT_IN_STACK_SAVE
2666 || call_expr_nargs (GIMPLE_STMT_OPERAND (stack_save, 1)) != 0)
2670 push_stmt_changes (&stmt);
2671 if (!set_rhs (&stmt,
2672 build_int_cst (TREE_TYPE (CALL_EXPR_ARG (call, 0)), 0)))
2674 discard_stmt_changes (&stmt);
2677 gcc_assert (stmt == stack_save);
2678 pop_stmt_changes (&stmt);
2680 return integer_zero_node;
2683 /* If va_list type is a simple pointer and nothing special is needed,
2684 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
2685 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
2686 pointer assignment. */
2689 optimize_stdarg_builtin (tree call)
2691 tree callee, lhs, rhs;
2692 bool va_list_simple_ptr;
2694 if (TREE_CODE (call) != CALL_EXPR)
2697 va_list_simple_ptr = POINTER_TYPE_P (va_list_type_node)
2698 && (TREE_TYPE (va_list_type_node) == void_type_node
2699 || TREE_TYPE (va_list_type_node) == char_type_node);
2701 callee = get_callee_fndecl (call);
2702 switch (DECL_FUNCTION_CODE (callee))
2704 case BUILT_IN_VA_START:
2705 if (!va_list_simple_ptr
2706 || targetm.expand_builtin_va_start != NULL
2707 || built_in_decls[BUILT_IN_NEXT_ARG] == NULL)
2710 if (call_expr_nargs (call) != 2)
2713 lhs = CALL_EXPR_ARG (call, 0);
2714 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
2715 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
2716 != TYPE_MAIN_VARIANT (va_list_type_node))
2719 lhs = build_fold_indirect_ref (lhs);
2720 rhs = build_call_expr (built_in_decls[BUILT_IN_NEXT_ARG],
2721 1, integer_zero_node);
2722 rhs = fold_convert (TREE_TYPE (lhs), rhs);
2723 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
2725 case BUILT_IN_VA_COPY:
2726 if (!va_list_simple_ptr)
2729 if (call_expr_nargs (call) != 2)
2732 lhs = CALL_EXPR_ARG (call, 0);
2733 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
2734 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
2735 != TYPE_MAIN_VARIANT (va_list_type_node))
2738 lhs = build_fold_indirect_ref (lhs);
2739 rhs = CALL_EXPR_ARG (call, 1);
2740 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs))
2741 != TYPE_MAIN_VARIANT (va_list_type_node))
2744 rhs = fold_convert (TREE_TYPE (lhs), rhs);
2745 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
2747 case BUILT_IN_VA_END:
2748 return integer_zero_node;
2755 /* Convert EXPR into a GIMPLE value suitable for substitution on the
2756 RHS of an assignment. Insert the necessary statements before
2758 When IGNORE is set, don't worry about the return value. */
2761 convert_to_gimple_builtin (block_stmt_iterator *si_p, tree expr, bool ignore)
2763 tree_stmt_iterator ti;
2764 tree stmt = bsi_stmt (*si_p);
2765 tree tmp, stmts = NULL;
2767 push_gimplify_context ();
2770 tmp = build_empty_stmt ();
2771 gimplify_and_add (expr, &stmts);
2774 tmp = get_initialized_tmp_var (expr, &stmts, NULL);
2775 pop_gimplify_context (NULL);
2777 if (EXPR_HAS_LOCATION (stmt))
2778 annotate_all_with_locus (&stmts, EXPR_LOCATION (stmt));
2780 /* The replacement can expose previously unreferenced variables. */
2781 for (ti = tsi_start (stmts); !tsi_end_p (ti); tsi_next (&ti))
2783 tree new_stmt = tsi_stmt (ti);
2784 find_new_referenced_vars (tsi_stmt_ptr (ti));
2785 bsi_insert_before (si_p, new_stmt, BSI_NEW_STMT);
2786 mark_symbols_for_renaming (new_stmt);
2794 /* A simple pass that attempts to fold all builtin functions. This pass
2795 is run after we've propagated as many constants as we can. */
2798 execute_fold_all_builtins (void)
2800 bool cfg_changed = false;
2802 unsigned int todoflags = 0;
2806 block_stmt_iterator i;
2807 for (i = bsi_start (bb); !bsi_end_p (i); )
2809 tree *stmtp = bsi_stmt_ptr (i);
2810 tree old_stmt = *stmtp;
2811 tree call = get_rhs (*stmtp);
2812 tree callee, result;
2813 enum built_in_function fcode;
2815 if (!call || TREE_CODE (call) != CALL_EXPR)
2820 callee = get_callee_fndecl (call);
2821 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
2826 fcode = DECL_FUNCTION_CODE (callee);
2828 result = ccp_fold_builtin (*stmtp, call);
2830 switch (DECL_FUNCTION_CODE (callee))
2832 case BUILT_IN_CONSTANT_P:
2833 /* Resolve __builtin_constant_p. If it hasn't been
2834 folded to integer_one_node by now, it's fairly
2835 certain that the value simply isn't constant. */
2836 result = integer_zero_node;
2839 case BUILT_IN_STACK_RESTORE:
2840 result = optimize_stack_restore (bb, *stmtp, i);
2846 case BUILT_IN_VA_START:
2847 case BUILT_IN_VA_END:
2848 case BUILT_IN_VA_COPY:
2849 /* These shouldn't be folded before pass_stdarg. */
2850 result = optimize_stdarg_builtin (*stmtp);
2860 if (dump_file && (dump_flags & TDF_DETAILS))
2862 fprintf (dump_file, "Simplified\n ");
2863 print_generic_stmt (dump_file, *stmtp, dump_flags);
2866 push_stmt_changes (stmtp);
2868 if (!set_rhs (stmtp, result))
2870 result = convert_to_gimple_builtin (&i, result,
2871 TREE_CODE (old_stmt)
2872 != GIMPLE_MODIFY_STMT);
2875 bool ok = set_rhs (stmtp, result);
2877 todoflags |= TODO_rebuild_alias;
2881 pop_stmt_changes (stmtp);
2883 if (maybe_clean_or_replace_eh_stmt (old_stmt, *stmtp)
2884 && tree_purge_dead_eh_edges (bb))
2887 if (dump_file && (dump_flags & TDF_DETAILS))
2889 fprintf (dump_file, "to\n ");
2890 print_generic_stmt (dump_file, *stmtp, dump_flags);
2891 fprintf (dump_file, "\n");
2894 /* Retry the same statement if it changed into another
2895 builtin, there might be new opportunities now. */
2896 call = get_rhs (*stmtp);
2897 if (!call || TREE_CODE (call) != CALL_EXPR)
2902 callee = get_callee_fndecl (call);
2904 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
2905 || DECL_FUNCTION_CODE (callee) == fcode)
2910 /* Delete unreachable blocks. */
2912 todoflags |= TODO_cleanup_cfg;
2918 struct gimple_opt_pass pass_fold_builtins =
2924 execute_fold_all_builtins, /* execute */
2927 0, /* static_pass_number */
2929 PROP_cfg | PROP_ssa, /* properties_required */
2930 0, /* properties_provided */
2931 0, /* properties_destroyed */
2932 0, /* todo_flags_start */
2935 | TODO_update_ssa /* todo_flags_finish */