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);
283 STRIP_USELESS_TYPE_CONVERSION (val);
284 if (is_gimple_min_invariant (val))
287 /* Variables declared 'const' without an initializer
288 have zero as the intializer if they may not be
289 overridden at link or run time. */
291 && targetm.binds_local_p (sym)
292 && (INTEGRAL_TYPE_P (TREE_TYPE (sym))
293 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (sym))))
294 return fold_convert (TREE_TYPE (sym), integer_zero_node);
300 /* Compute a default value for variable VAR and store it in the
301 CONST_VAL array. The following rules are used to get default
304 1- Global and static variables that are declared constant are
307 2- Any other value is considered UNDEFINED. This is useful when
308 considering PHI nodes. PHI arguments that are undefined do not
309 change the constant value of the PHI node, which allows for more
310 constants to be propagated.
312 3- If SSA_NAME_VALUE is set and it is a constant, its value is
315 4- Variables defined by statements other than assignments and PHI
316 nodes are considered VARYING.
318 5- Initial values of variables that are not GIMPLE registers are
319 considered VARYING. */
322 get_default_value (tree var)
324 tree sym = SSA_NAME_VAR (var);
325 prop_value_t val = { UNINITIALIZED, NULL_TREE, NULL_TREE };
328 if (!do_store_ccp && !is_gimple_reg (var))
330 /* Short circuit for regular CCP. We are not interested in any
331 non-register when DO_STORE_CCP is false. */
332 val.lattice_val = VARYING;
334 else if (SSA_NAME_VALUE (var)
335 && is_gimple_min_invariant (SSA_NAME_VALUE (var)))
337 val.lattice_val = CONSTANT;
338 val.value = SSA_NAME_VALUE (var);
340 else if ((cst_val = get_symbol_constant_value (sym)) != NULL_TREE)
342 /* Globals and static variables declared 'const' take their
344 val.lattice_val = CONSTANT;
350 tree stmt = SSA_NAME_DEF_STMT (var);
352 if (IS_EMPTY_STMT (stmt))
354 /* Variables defined by an empty statement are those used
355 before being initialized. If VAR is a local variable, we
356 can assume initially that it is UNDEFINED, otherwise we must
357 consider it VARYING. */
358 if (is_gimple_reg (sym) && TREE_CODE (sym) != PARM_DECL)
359 val.lattice_val = UNDEFINED;
361 val.lattice_val = VARYING;
363 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
364 || TREE_CODE (stmt) == PHI_NODE)
366 /* Any other variable defined by an assignment or a PHI node
367 is considered UNDEFINED. */
368 val.lattice_val = UNDEFINED;
372 /* Otherwise, VAR will never take on a constant value. */
373 val.lattice_val = VARYING;
381 /* Get the constant value associated with variable VAR. */
383 static inline prop_value_t *
388 if (const_val == NULL)
391 val = &const_val[SSA_NAME_VERSION (var)];
392 if (val->lattice_val == UNINITIALIZED)
393 *val = get_default_value (var);
398 /* Sets the value associated with VAR to VARYING. */
401 set_value_varying (tree var)
403 prop_value_t *val = &const_val[SSA_NAME_VERSION (var)];
405 val->lattice_val = VARYING;
406 val->value = NULL_TREE;
407 val->mem_ref = NULL_TREE;
410 /* For float types, modify the value of VAL to make ccp work correctly
411 for non-standard values (-0, NaN):
413 If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0.
414 If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED.
415 This is to fix the following problem (see PR 29921): Suppose we have
419 and we set value of y to NaN. This causes value of x to be set to NaN.
420 When we later determine that y is in fact VARYING, fold uses the fact
421 that HONOR_NANS is false, and we try to change the value of x to 0,
422 causing an ICE. With HONOR_NANS being false, the real appearance of
423 NaN would cause undefined behavior, though, so claiming that y (and x)
424 are UNDEFINED initially is correct. */
427 canonicalize_float_value (prop_value_t *val)
429 enum machine_mode mode;
433 if (val->lattice_val != CONSTANT
434 || TREE_CODE (val->value) != REAL_CST)
437 d = TREE_REAL_CST (val->value);
438 type = TREE_TYPE (val->value);
439 mode = TYPE_MODE (type);
441 if (!HONOR_SIGNED_ZEROS (mode)
442 && REAL_VALUE_MINUS_ZERO (d))
444 val->value = build_real (type, dconst0);
448 if (!HONOR_NANS (mode)
449 && REAL_VALUE_ISNAN (d))
451 val->lattice_val = UNDEFINED;
458 /* Set the value for variable VAR to NEW_VAL. Return true if the new
459 value is different from VAR's previous value. */
462 set_lattice_value (tree var, prop_value_t new_val)
464 prop_value_t *old_val = get_value (var);
466 canonicalize_float_value (&new_val);
468 /* Lattice transitions must always be monotonically increasing in
469 value. If *OLD_VAL and NEW_VAL are the same, return false to
470 inform the caller that this was a non-transition. */
472 gcc_assert (old_val->lattice_val < new_val.lattice_val
473 || (old_val->lattice_val == new_val.lattice_val
474 && ((!old_val->value && !new_val.value)
475 || operand_equal_p (old_val->value, new_val.value, 0))
476 && old_val->mem_ref == new_val.mem_ref));
478 if (old_val->lattice_val != new_val.lattice_val)
480 if (dump_file && (dump_flags & TDF_DETAILS))
482 dump_lattice_value (dump_file, "Lattice value changed to ", new_val);
483 fprintf (dump_file, ". Adding SSA edges to worklist.\n");
488 gcc_assert (new_val.lattice_val != UNDEFINED);
496 /* Return the likely CCP lattice value for STMT.
498 If STMT has no operands, then return CONSTANT.
500 Else if undefinedness of operands of STMT cause its value to be
501 undefined, then return UNDEFINED.
503 Else if any operands of STMT are constants, then return CONSTANT.
505 Else return VARYING. */
508 likely_value (tree stmt)
510 bool has_constant_operand, has_undefined_operand, all_undefined_operands;
515 ann = stmt_ann (stmt);
517 /* If the statement has volatile operands, it won't fold to a
519 if (ann->has_volatile_ops)
522 /* If we are not doing store-ccp, statements with loads
523 and/or stores will never fold into a constant. */
525 && !ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
529 /* A CALL_EXPR is assumed to be varying. NOTE: This may be overly
530 conservative, in the presence of const and pure calls. */
531 if (get_call_expr_in (stmt) != NULL_TREE)
534 /* Anything other than assignments and conditional jumps are not
535 interesting for CCP. */
536 if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT
537 && !(TREE_CODE (stmt) == RETURN_EXPR && get_rhs (stmt) != NULL_TREE)
538 && TREE_CODE (stmt) != COND_EXPR
539 && TREE_CODE (stmt) != SWITCH_EXPR)
542 if (is_gimple_min_invariant (get_rhs (stmt)))
545 has_constant_operand = false;
546 has_undefined_operand = false;
547 all_undefined_operands = true;
548 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
550 prop_value_t *val = get_value (use);
552 if (val->lattice_val == UNDEFINED)
553 has_undefined_operand = true;
555 all_undefined_operands = false;
557 if (val->lattice_val == CONSTANT)
558 has_constant_operand = true;
561 /* If the operation combines operands like COMPLEX_EXPR make sure to
562 not mark the result UNDEFINED if only one part of the result is
564 if (has_undefined_operand
565 && all_undefined_operands)
567 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
568 && has_undefined_operand)
570 switch (TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)))
572 /* Unary operators are handled with all_undefined_operands. */
575 case POINTER_PLUS_EXPR:
576 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected.
577 Not bitwise operators, one VARYING operand may specify the
578 result completely. Not logical operators for the same reason.
579 Not COMPLEX_EXPR as one VARYING operand makes the result partly
580 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because
581 the undefined operand may be promoted. */
588 /* If there was an UNDEFINED operand but the result may be not UNDEFINED
589 fall back to VARYING even if there were CONSTANT operands. */
590 if (has_undefined_operand)
593 if (has_constant_operand
594 /* We do not consider virtual operands here -- load from read-only
595 memory may have only VARYING virtual operands, but still be
597 || ZERO_SSA_OPERANDS (stmt, SSA_OP_USE))
603 /* Returns true if STMT cannot be constant. */
606 surely_varying_stmt_p (tree stmt)
608 /* If the statement has operands that we cannot handle, it cannot be
610 if (stmt_ann (stmt)->has_volatile_ops)
613 if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
618 /* We can only handle simple loads and stores. */
619 if (!stmt_makes_single_load (stmt)
620 && !stmt_makes_single_store (stmt))
624 /* If it contains a call, it is varying. */
625 if (get_call_expr_in (stmt) != NULL_TREE)
628 /* Anything other than assignments and conditional jumps are not
629 interesting for CCP. */
630 if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT
631 && !(TREE_CODE (stmt) == RETURN_EXPR && get_rhs (stmt) != NULL_TREE)
632 && TREE_CODE (stmt) != COND_EXPR
633 && TREE_CODE (stmt) != SWITCH_EXPR)
639 /* Initialize local data structures for CCP. */
642 ccp_initialize (void)
646 const_val = XCNEWVEC (prop_value_t, num_ssa_names);
648 /* Initialize simulation flags for PHI nodes and statements. */
651 block_stmt_iterator i;
653 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
655 tree stmt = bsi_stmt (i);
656 bool is_varying = surely_varying_stmt_p (stmt);
663 /* If the statement will not produce a constant, mark
664 all its outputs VARYING. */
665 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
668 set_value_varying (def);
672 DONT_SIMULATE_AGAIN (stmt) = is_varying;
676 /* Now process PHI nodes. We never set DONT_SIMULATE_AGAIN on phi node,
677 since we do not know which edges are executable yet, except for
678 phi nodes for virtual operands when we do not do store ccp. */
683 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
685 if (!do_store_ccp && !is_gimple_reg (PHI_RESULT (phi)))
686 DONT_SIMULATE_AGAIN (phi) = true;
688 DONT_SIMULATE_AGAIN (phi) = false;
694 /* Do final substitution of propagated values, cleanup the flowgraph and
695 free allocated storage.
697 Return TRUE when something was optimized. */
702 /* Perform substitutions based on the known constant values. */
703 bool something_changed = substitute_and_fold (const_val, false);
707 return something_changed;;
711 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
714 any M UNDEFINED = any
715 any M VARYING = VARYING
716 Ci M Cj = Ci if (i == j)
717 Ci M Cj = VARYING if (i != j)
721 ccp_lattice_meet (prop_value_t *val1, prop_value_t *val2)
723 if (val1->lattice_val == UNDEFINED)
725 /* UNDEFINED M any = any */
728 else if (val2->lattice_val == UNDEFINED)
730 /* any M UNDEFINED = any
731 Nothing to do. VAL1 already contains the value we want. */
734 else if (val1->lattice_val == VARYING
735 || val2->lattice_val == VARYING)
737 /* any M VARYING = VARYING. */
738 val1->lattice_val = VARYING;
739 val1->value = NULL_TREE;
740 val1->mem_ref = NULL_TREE;
742 else if (val1->lattice_val == CONSTANT
743 && val2->lattice_val == CONSTANT
744 && simple_cst_equal (val1->value, val2->value) == 1
746 || (val1->mem_ref && val2->mem_ref
747 && operand_equal_p (val1->mem_ref, val2->mem_ref, 0))))
749 /* Ci M Cj = Ci if (i == j)
750 Ci M Cj = VARYING if (i != j)
752 If these two values come from memory stores, make sure that
753 they come from the same memory reference. */
754 val1->lattice_val = CONSTANT;
755 val1->value = val1->value;
756 val1->mem_ref = val1->mem_ref;
760 /* Any other combination is VARYING. */
761 val1->lattice_val = VARYING;
762 val1->value = NULL_TREE;
763 val1->mem_ref = NULL_TREE;
768 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
769 lattice values to determine PHI_NODE's lattice value. The value of a
770 PHI node is determined calling ccp_lattice_meet with all the arguments
771 of the PHI node that are incoming via executable edges. */
773 static enum ssa_prop_result
774 ccp_visit_phi_node (tree phi)
777 prop_value_t *old_val, new_val;
779 if (dump_file && (dump_flags & TDF_DETAILS))
781 fprintf (dump_file, "\nVisiting PHI node: ");
782 print_generic_expr (dump_file, phi, dump_flags);
785 old_val = get_value (PHI_RESULT (phi));
786 switch (old_val->lattice_val)
789 return SSA_PROP_VARYING;
796 new_val.lattice_val = UNDEFINED;
797 new_val.value = NULL_TREE;
798 new_val.mem_ref = NULL_TREE;
805 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
807 /* Compute the meet operator over all the PHI arguments flowing
808 through executable edges. */
809 edge e = PHI_ARG_EDGE (phi, i);
811 if (dump_file && (dump_flags & TDF_DETAILS))
814 "\n Argument #%d (%d -> %d %sexecutable)\n",
815 i, e->src->index, e->dest->index,
816 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
819 /* If the incoming edge is executable, Compute the meet operator for
820 the existing value of the PHI node and the current PHI argument. */
821 if (e->flags & EDGE_EXECUTABLE)
823 tree arg = PHI_ARG_DEF (phi, i);
824 prop_value_t arg_val;
826 if (is_gimple_min_invariant (arg))
828 arg_val.lattice_val = CONSTANT;
830 arg_val.mem_ref = NULL_TREE;
833 arg_val = *(get_value (arg));
835 ccp_lattice_meet (&new_val, &arg_val);
837 if (dump_file && (dump_flags & TDF_DETAILS))
839 fprintf (dump_file, "\t");
840 print_generic_expr (dump_file, arg, dump_flags);
841 dump_lattice_value (dump_file, "\tValue: ", arg_val);
842 fprintf (dump_file, "\n");
845 if (new_val.lattice_val == VARYING)
850 if (dump_file && (dump_flags & TDF_DETAILS))
852 dump_lattice_value (dump_file, "\n PHI node value: ", new_val);
853 fprintf (dump_file, "\n\n");
856 /* Make the transition to the new value. */
857 if (set_lattice_value (PHI_RESULT (phi), new_val))
859 if (new_val.lattice_val == VARYING)
860 return SSA_PROP_VARYING;
862 return SSA_PROP_INTERESTING;
865 return SSA_PROP_NOT_INTERESTING;
869 /* CCP specific front-end to the non-destructive constant folding
872 Attempt to simplify the RHS of STMT knowing that one or more
873 operands are constants.
875 If simplification is possible, return the simplified RHS,
876 otherwise return the original RHS. */
881 tree rhs = get_rhs (stmt);
882 enum tree_code code = TREE_CODE (rhs);
883 enum tree_code_class kind = TREE_CODE_CLASS (code);
884 tree retval = NULL_TREE;
886 if (TREE_CODE (rhs) == SSA_NAME)
888 /* If the RHS is an SSA_NAME, return its known constant value,
890 return get_value (rhs)->value;
892 else if (do_store_ccp && stmt_makes_single_load (stmt))
894 /* If the RHS is a memory load, see if the VUSEs associated with
895 it are a valid constant for that memory load. */
896 prop_value_t *val = get_value_loaded_by (stmt, const_val);
897 if (val && val->mem_ref)
899 if (operand_equal_p (val->mem_ref, rhs, 0))
902 /* If RHS is extracting REALPART_EXPR or IMAGPART_EXPR of a
903 complex type with a known constant value, return it. */
904 if ((TREE_CODE (rhs) == REALPART_EXPR
905 || TREE_CODE (rhs) == IMAGPART_EXPR)
906 && operand_equal_p (val->mem_ref, TREE_OPERAND (rhs, 0), 0))
907 return fold_build1 (TREE_CODE (rhs), TREE_TYPE (rhs), val->value);
912 /* Unary operators. Note that we know the single operand must
913 be a constant. So this should almost always return a
915 if (kind == tcc_unary)
917 /* Handle unary operators which can appear in GIMPLE form. */
918 tree op0 = TREE_OPERAND (rhs, 0);
920 /* Simplify the operand down to a constant. */
921 if (TREE_CODE (op0) == SSA_NAME)
923 prop_value_t *val = get_value (op0);
924 if (val->lattice_val == CONSTANT)
925 op0 = get_value (op0)->value;
928 /* Conversions are useless for CCP purposes if they are
929 value-preserving. Thus the restrictions that
930 useless_type_conversion_p places for pointer type conversions do
931 not apply here. Substitution later will only substitute to
933 if ((code == NOP_EXPR || code == CONVERT_EXPR)
934 && ((POINTER_TYPE_P (TREE_TYPE (rhs))
935 && POINTER_TYPE_P (TREE_TYPE (op0)))
936 || useless_type_conversion_p (TREE_TYPE (rhs), TREE_TYPE (op0))))
938 return fold_unary (code, TREE_TYPE (rhs), op0);
941 /* Binary and comparison operators. We know one or both of the
942 operands are constants. */
943 else if (kind == tcc_binary
944 || kind == tcc_comparison
945 || code == TRUTH_AND_EXPR
946 || code == TRUTH_OR_EXPR
947 || code == TRUTH_XOR_EXPR)
949 /* Handle binary and comparison operators that can appear in
951 tree op0 = TREE_OPERAND (rhs, 0);
952 tree op1 = TREE_OPERAND (rhs, 1);
954 /* Simplify the operands down to constants when appropriate. */
955 if (TREE_CODE (op0) == SSA_NAME)
957 prop_value_t *val = get_value (op0);
958 if (val->lattice_val == CONSTANT)
962 if (TREE_CODE (op1) == SSA_NAME)
964 prop_value_t *val = get_value (op1);
965 if (val->lattice_val == CONSTANT)
969 return fold_binary (code, TREE_TYPE (rhs), op0, op1);
972 else if (kind == tcc_declaration)
973 return get_symbol_constant_value (rhs);
975 else if (kind == tcc_reference)
976 return fold_const_aggregate_ref (rhs);
978 /* Handle propagating invariant addresses into address operations.
979 The folding we do here matches that in tree-ssa-forwprop.c. */
980 else if (code == ADDR_EXPR)
983 base = &TREE_OPERAND (rhs, 0);
984 while (handled_component_p (*base))
985 base = &TREE_OPERAND (*base, 0);
986 if (TREE_CODE (*base) == INDIRECT_REF
987 && TREE_CODE (TREE_OPERAND (*base, 0)) == SSA_NAME)
989 prop_value_t *val = get_value (TREE_OPERAND (*base, 0));
990 if (val->lattice_val == CONSTANT
991 && TREE_CODE (val->value) == ADDR_EXPR
992 && useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (*base, 0)),
993 TREE_TYPE (val->value))
994 && useless_type_conversion_p (TREE_TYPE (*base),
995 TREE_TYPE (TREE_OPERAND (val->value, 0))))
997 /* We need to return a new tree, not modify the IL or share
998 parts of it. So play some tricks to avoid manually
1000 tree ret, save = *base;
1001 *base = TREE_OPERAND (val->value, 0);
1002 ret = unshare_expr (rhs);
1003 recompute_tree_invariant_for_addr_expr (ret);
1010 /* We may be able to fold away calls to builtin functions if their
1011 arguments are constants. */
1012 else if (code == CALL_EXPR
1013 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
1014 && TREE_CODE (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)) == FUNCTION_DECL
1015 && DECL_BUILT_IN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
1017 if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_USE))
1022 use_operand_p var_p;
1024 /* Preserve the original values of every operand. */
1025 orig = XNEWVEC (tree, NUM_SSA_OPERANDS (stmt, SSA_OP_USE));
1026 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE)
1029 /* Substitute operands with their values and try to fold. */
1030 replace_uses_in (stmt, NULL, const_val);
1031 retval = fold_call_expr (rhs, false);
1033 /* Restore operands to their original form. */
1035 FOR_EACH_SSA_USE_OPERAND (var_p, stmt, iter, SSA_OP_USE)
1036 SET_USE (var_p, orig[i++]);
1043 /* If we got a simplified form, see if we need to convert its type. */
1045 return fold_convert (TREE_TYPE (rhs), retval);
1047 /* No simplification was possible. */
1052 /* Return the tree representing the element referenced by T if T is an
1053 ARRAY_REF or COMPONENT_REF into constant aggregates. Return
1054 NULL_TREE otherwise. */
1057 fold_const_aggregate_ref (tree t)
1059 prop_value_t *value;
1060 tree base, ctor, idx, field;
1061 unsigned HOST_WIDE_INT cnt;
1064 switch (TREE_CODE (t))
1067 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1068 DECL_INITIAL. If BASE is a nested reference into another
1069 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1070 the inner reference. */
1071 base = TREE_OPERAND (t, 0);
1072 switch (TREE_CODE (base))
1075 if (!TREE_READONLY (base)
1076 || TREE_CODE (TREE_TYPE (base)) != ARRAY_TYPE
1077 || !targetm.binds_local_p (base))
1080 ctor = DECL_INITIAL (base);
1085 ctor = fold_const_aggregate_ref (base);
1097 if (ctor == NULL_TREE
1098 || (TREE_CODE (ctor) != CONSTRUCTOR
1099 && TREE_CODE (ctor) != STRING_CST)
1100 || !TREE_STATIC (ctor))
1103 /* Get the index. If we have an SSA_NAME, try to resolve it
1104 with the current lattice value for the SSA_NAME. */
1105 idx = TREE_OPERAND (t, 1);
1106 switch (TREE_CODE (idx))
1109 if ((value = get_value (idx))
1110 && value->lattice_val == CONSTANT
1111 && TREE_CODE (value->value) == INTEGER_CST)
1124 /* Fold read from constant string. */
1125 if (TREE_CODE (ctor) == STRING_CST)
1127 if ((TYPE_MODE (TREE_TYPE (t))
1128 == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1129 && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1131 && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) == 1
1132 && compare_tree_int (idx, TREE_STRING_LENGTH (ctor)) < 0)
1133 return build_int_cst_type (TREE_TYPE (t),
1134 (TREE_STRING_POINTER (ctor)
1135 [TREE_INT_CST_LOW (idx)]));
1139 /* Whoo-hoo! I'll fold ya baby. Yeah! */
1140 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
1141 if (tree_int_cst_equal (cfield, idx))
1143 STRIP_USELESS_TYPE_CONVERSION (cval);
1149 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1150 DECL_INITIAL. If BASE is a nested reference into another
1151 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1152 the inner reference. */
1153 base = TREE_OPERAND (t, 0);
1154 switch (TREE_CODE (base))
1157 if (!TREE_READONLY (base)
1158 || TREE_CODE (TREE_TYPE (base)) != RECORD_TYPE
1159 || !targetm.binds_local_p (base))
1162 ctor = DECL_INITIAL (base);
1167 ctor = fold_const_aggregate_ref (base);
1174 if (ctor == NULL_TREE
1175 || TREE_CODE (ctor) != CONSTRUCTOR
1176 || !TREE_STATIC (ctor))
1179 field = TREE_OPERAND (t, 1);
1181 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
1183 /* FIXME: Handle bit-fields. */
1184 && ! DECL_BIT_FIELD (cfield))
1186 STRIP_USELESS_TYPE_CONVERSION (cval);
1194 tree c = fold_const_aggregate_ref (TREE_OPERAND (t, 0));
1195 if (c && TREE_CODE (c) == COMPLEX_CST)
1196 return fold_build1 (TREE_CODE (t), TREE_TYPE (t), c);
1202 tree base = TREE_OPERAND (t, 0);
1203 if (TREE_CODE (base) == SSA_NAME
1204 && (value = get_value (base))
1205 && value->lattice_val == CONSTANT
1206 && TREE_CODE (value->value) == ADDR_EXPR)
1207 return fold_const_aggregate_ref (TREE_OPERAND (value->value, 0));
1218 /* Evaluate statement STMT. */
1221 evaluate_stmt (tree stmt)
1224 tree simplified = NULL_TREE;
1225 ccp_lattice_t likelyvalue = likely_value (stmt);
1228 val.mem_ref = NULL_TREE;
1230 fold_defer_overflow_warnings ();
1232 /* If the statement is likely to have a CONSTANT result, then try
1233 to fold the statement to determine the constant value. */
1234 if (likelyvalue == CONSTANT)
1235 simplified = ccp_fold (stmt);
1236 /* If the statement is likely to have a VARYING result, then do not
1237 bother folding the statement. */
1238 else if (likelyvalue == VARYING)
1239 simplified = get_rhs (stmt);
1241 is_constant = simplified && is_gimple_min_invariant (simplified);
1243 fold_undefer_overflow_warnings (is_constant, stmt, 0);
1245 if (dump_file && (dump_flags & TDF_DETAILS))
1247 fprintf (dump_file, "which is likely ");
1248 switch (likelyvalue)
1251 fprintf (dump_file, "CONSTANT");
1254 fprintf (dump_file, "UNDEFINED");
1257 fprintf (dump_file, "VARYING");
1261 fprintf (dump_file, "\n");
1266 /* The statement produced a constant value. */
1267 val.lattice_val = CONSTANT;
1268 val.value = simplified;
1272 /* The statement produced a nonconstant value. If the statement
1273 had UNDEFINED operands, then the result of the statement
1274 should be UNDEFINED. Otherwise, the statement is VARYING. */
1275 if (likelyvalue == UNDEFINED)
1276 val.lattice_val = likelyvalue;
1278 val.lattice_val = VARYING;
1280 val.value = NULL_TREE;
1287 /* Visit the assignment statement STMT. Set the value of its LHS to the
1288 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
1289 creates virtual definitions, set the value of each new name to that
1290 of the RHS (if we can derive a constant out of the RHS). */
1292 static enum ssa_prop_result
1293 visit_assignment (tree stmt, tree *output_p)
1297 enum ssa_prop_result retval;
1299 lhs = GIMPLE_STMT_OPERAND (stmt, 0);
1300 rhs = GIMPLE_STMT_OPERAND (stmt, 1);
1302 if (TREE_CODE (rhs) == SSA_NAME)
1304 /* For a simple copy operation, we copy the lattice values. */
1305 prop_value_t *nval = get_value (rhs);
1308 else if (do_store_ccp && stmt_makes_single_load (stmt))
1310 /* Same as above, but the RHS is not a gimple register and yet
1311 has a known VUSE. If STMT is loading from the same memory
1312 location that created the SSA_NAMEs for the virtual operands,
1313 we can propagate the value on the RHS. */
1314 prop_value_t *nval = get_value_loaded_by (stmt, const_val);
1318 && operand_equal_p (nval->mem_ref, rhs, 0))
1321 val = evaluate_stmt (stmt);
1324 /* Evaluate the statement. */
1325 val = evaluate_stmt (stmt);
1327 retval = SSA_PROP_NOT_INTERESTING;
1329 /* Set the lattice value of the statement's output. */
1330 if (TREE_CODE (lhs) == SSA_NAME)
1332 /* If STMT is an assignment to an SSA_NAME, we only have one
1334 if (set_lattice_value (lhs, val))
1337 if (val.lattice_val == VARYING)
1338 retval = SSA_PROP_VARYING;
1340 retval = SSA_PROP_INTERESTING;
1343 else if (do_store_ccp && stmt_makes_single_store (stmt))
1345 /* Otherwise, set the names in VDEF operands to the new
1346 constant value and mark the LHS as the memory reference
1347 associated with VAL. */
1352 /* Mark VAL as stored in the LHS of this assignment. */
1353 if (val.lattice_val == CONSTANT)
1356 /* Set the value of every VDEF to VAL. */
1358 FOR_EACH_SSA_TREE_OPERAND (vdef, stmt, i, SSA_OP_VIRTUAL_DEFS)
1360 /* See PR 29801. We may have VDEFs for read-only variables
1361 (see the handling of unmodifiable variables in
1362 add_virtual_operand); do not attempt to change their value. */
1363 if (get_symbol_constant_value (SSA_NAME_VAR (vdef)) != NULL_TREE)
1366 changed |= set_lattice_value (vdef, val);
1369 /* Note that for propagation purposes, we are only interested in
1370 visiting statements that load the exact same memory reference
1371 stored here. Those statements will have the exact same list
1372 of virtual uses, so it is enough to set the output of this
1373 statement to be its first virtual definition. */
1374 *output_p = first_vdef (stmt);
1377 if (val.lattice_val == VARYING)
1378 retval = SSA_PROP_VARYING;
1380 retval = SSA_PROP_INTERESTING;
1388 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
1389 if it can determine which edge will be taken. Otherwise, return
1390 SSA_PROP_VARYING. */
1392 static enum ssa_prop_result
1393 visit_cond_stmt (tree stmt, edge *taken_edge_p)
1398 block = bb_for_stmt (stmt);
1399 val = evaluate_stmt (stmt);
1401 /* Find which edge out of the conditional block will be taken and add it
1402 to the worklist. If no single edge can be determined statically,
1403 return SSA_PROP_VARYING to feed all the outgoing edges to the
1404 propagation engine. */
1405 *taken_edge_p = val.value ? find_taken_edge (block, val.value) : 0;
1407 return SSA_PROP_INTERESTING;
1409 return SSA_PROP_VARYING;
1413 /* Evaluate statement STMT. If the statement produces an output value and
1414 its evaluation changes the lattice value of its output, return
1415 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
1418 If STMT is a conditional branch and we can determine its truth
1419 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
1420 value, return SSA_PROP_VARYING. */
1422 static enum ssa_prop_result
1423 ccp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
1428 if (dump_file && (dump_flags & TDF_DETAILS))
1430 fprintf (dump_file, "\nVisiting statement:\n");
1431 print_generic_stmt (dump_file, stmt, dump_flags);
1434 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
1436 /* If the statement is an assignment that produces a single
1437 output value, evaluate its RHS to see if the lattice value of
1438 its output has changed. */
1439 return visit_assignment (stmt, output_p);
1441 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
1443 /* If STMT is a conditional branch, see if we can determine
1444 which branch will be taken. */
1445 return visit_cond_stmt (stmt, taken_edge_p);
1448 /* Any other kind of statement is not interesting for constant
1449 propagation and, therefore, not worth simulating. */
1450 if (dump_file && (dump_flags & TDF_DETAILS))
1451 fprintf (dump_file, "No interesting values produced. Marked VARYING.\n");
1453 /* Definitions made by statements other than assignments to
1454 SSA_NAMEs represent unknown modifications to their outputs.
1455 Mark them VARYING. */
1456 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
1458 prop_value_t v = { VARYING, NULL_TREE, NULL_TREE };
1459 set_lattice_value (def, v);
1462 return SSA_PROP_VARYING;
1466 /* Main entry point for SSA Conditional Constant Propagation. */
1469 execute_ssa_ccp (bool store_ccp)
1471 do_store_ccp = store_ccp;
1473 ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node);
1474 if (ccp_finalize ())
1475 return (TODO_cleanup_cfg | TODO_update_ssa | TODO_remove_unused_locals);
1484 return execute_ssa_ccp (false);
1491 return flag_tree_ccp != 0;
1495 struct gimple_opt_pass pass_ccp =
1500 gate_ccp, /* gate */
1501 do_ssa_ccp, /* execute */
1504 0, /* static_pass_number */
1505 TV_TREE_CCP, /* tv_id */
1506 PROP_cfg | PROP_ssa, /* properties_required */
1507 0, /* properties_provided */
1508 0, /* properties_destroyed */
1509 0, /* todo_flags_start */
1510 TODO_dump_func | TODO_verify_ssa
1511 | TODO_verify_stmts | TODO_ggc_collect/* todo_flags_finish */
1517 do_ssa_store_ccp (void)
1519 /* If STORE-CCP is not enabled, we just run regular CCP. */
1520 return execute_ssa_ccp (flag_tree_store_ccp != 0);
1524 gate_store_ccp (void)
1526 /* STORE-CCP is enabled only with -ftree-store-ccp, but when
1527 -fno-tree-store-ccp is specified, we should run regular CCP.
1528 That's why the pass is enabled with either flag. */
1529 return flag_tree_store_ccp != 0 || flag_tree_ccp != 0;
1533 struct gimple_opt_pass pass_store_ccp =
1537 "store_ccp", /* name */
1538 gate_store_ccp, /* gate */
1539 do_ssa_store_ccp, /* execute */
1542 0, /* static_pass_number */
1543 TV_TREE_STORE_CCP, /* tv_id */
1544 PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
1545 0, /* properties_provided */
1546 0, /* properties_destroyed */
1547 0, /* todo_flags_start */
1548 TODO_dump_func | TODO_verify_ssa
1549 | TODO_verify_stmts | TODO_ggc_collect/* todo_flags_finish */
1553 /* A subroutine of fold_stmt_r. Attempts to fold *(A+O) to A[X].
1554 BASE is an array type. OFFSET is a byte displacement. ORIG_TYPE
1555 is the desired result type. */
1558 maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type,
1559 bool allow_negative_idx)
1561 tree min_idx, idx, idx_type, elt_offset = integer_zero_node;
1562 tree array_type, elt_type, elt_size;
1565 /* If BASE is an ARRAY_REF, we can pick up another offset (this time
1566 measured in units of the size of elements type) from that ARRAY_REF).
1567 We can't do anything if either is variable.
1569 The case we handle here is *(&A[N]+O). */
1570 if (TREE_CODE (base) == ARRAY_REF)
1572 tree low_bound = array_ref_low_bound (base);
1574 elt_offset = TREE_OPERAND (base, 1);
1575 if (TREE_CODE (low_bound) != INTEGER_CST
1576 || TREE_CODE (elt_offset) != INTEGER_CST)
1579 elt_offset = int_const_binop (MINUS_EXPR, elt_offset, low_bound, 0);
1580 base = TREE_OPERAND (base, 0);
1583 /* Ignore stupid user tricks of indexing non-array variables. */
1584 array_type = TREE_TYPE (base);
1585 if (TREE_CODE (array_type) != ARRAY_TYPE)
1587 elt_type = TREE_TYPE (array_type);
1588 if (!useless_type_conversion_p (orig_type, elt_type))
1591 /* Use signed size type for intermediate computation on the index. */
1592 idx_type = signed_type_for (size_type_node);
1594 /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the
1595 element type (so we can use the alignment if it's not constant).
1596 Otherwise, compute the offset as an index by using a division. If the
1597 division isn't exact, then don't do anything. */
1598 elt_size = TYPE_SIZE_UNIT (elt_type);
1601 if (integer_zerop (offset))
1603 if (TREE_CODE (elt_size) != INTEGER_CST)
1604 elt_size = size_int (TYPE_ALIGN (elt_type));
1606 idx = build_int_cst (idx_type, 0);
1610 unsigned HOST_WIDE_INT lquo, lrem;
1611 HOST_WIDE_INT hquo, hrem;
1614 /* The final array offset should be signed, so we need
1615 to sign-extend the (possibly pointer) offset here
1616 and use signed division. */
1617 soffset = double_int_sext (tree_to_double_int (offset),
1618 TYPE_PRECISION (TREE_TYPE (offset)));
1619 if (TREE_CODE (elt_size) != INTEGER_CST
1620 || div_and_round_double (TRUNC_DIV_EXPR, 0,
1621 soffset.low, soffset.high,
1622 TREE_INT_CST_LOW (elt_size),
1623 TREE_INT_CST_HIGH (elt_size),
1624 &lquo, &hquo, &lrem, &hrem)
1628 idx = build_int_cst_wide (idx_type, lquo, hquo);
1631 /* Assume the low bound is zero. If there is a domain type, get the
1632 low bound, if any, convert the index into that type, and add the
1634 min_idx = build_int_cst (idx_type, 0);
1635 domain_type = TYPE_DOMAIN (array_type);
1638 idx_type = domain_type;
1639 if (TYPE_MIN_VALUE (idx_type))
1640 min_idx = TYPE_MIN_VALUE (idx_type);
1642 min_idx = fold_convert (idx_type, min_idx);
1644 if (TREE_CODE (min_idx) != INTEGER_CST)
1647 elt_offset = fold_convert (idx_type, elt_offset);
1650 if (!integer_zerop (min_idx))
1651 idx = int_const_binop (PLUS_EXPR, idx, min_idx, 0);
1652 if (!integer_zerop (elt_offset))
1653 idx = int_const_binop (PLUS_EXPR, idx, elt_offset, 0);
1655 /* Make sure to possibly truncate late after offsetting. */
1656 idx = fold_convert (idx_type, idx);
1658 /* We don't want to construct access past array bounds. For example
1661 should not be simplified into (*c)[14] or tree-vrp will
1662 give false warnings. The same is true for
1663 struct A { long x; char d[0]; } *a;
1665 which should be not folded to &a->d[-8]. */
1667 && TYPE_MAX_VALUE (domain_type)
1668 && TREE_CODE (TYPE_MAX_VALUE (domain_type)) == INTEGER_CST)
1670 tree up_bound = TYPE_MAX_VALUE (domain_type);
1672 if (tree_int_cst_lt (up_bound, idx)
1673 /* Accesses after the end of arrays of size 0 (gcc
1674 extension) and 1 are likely intentional ("struct
1676 && compare_tree_int (up_bound, 1) > 0)
1680 && TYPE_MIN_VALUE (domain_type))
1682 if (!allow_negative_idx
1683 && TREE_CODE (TYPE_MIN_VALUE (domain_type)) == INTEGER_CST
1684 && tree_int_cst_lt (idx, TYPE_MIN_VALUE (domain_type)))
1687 else if (!allow_negative_idx
1688 && compare_tree_int (idx, 0) < 0)
1691 return build4 (ARRAY_REF, elt_type, base, idx, NULL_TREE, NULL_TREE);
1695 /* Attempt to fold *(S+O) to S.X.
1696 BASE is a record type. OFFSET is a byte displacement. ORIG_TYPE
1697 is the desired result type. */
1700 maybe_fold_offset_to_component_ref (tree record_type, tree base, tree offset,
1701 tree orig_type, bool base_is_ptr)
1703 tree f, t, field_type, tail_array_field, field_offset;
1707 if (TREE_CODE (record_type) != RECORD_TYPE
1708 && TREE_CODE (record_type) != UNION_TYPE
1709 && TREE_CODE (record_type) != QUAL_UNION_TYPE)
1712 /* Short-circuit silly cases. */
1713 if (useless_type_conversion_p (record_type, orig_type))
1716 tail_array_field = NULL_TREE;
1717 for (f = TYPE_FIELDS (record_type); f ; f = TREE_CHAIN (f))
1721 if (TREE_CODE (f) != FIELD_DECL)
1723 if (DECL_BIT_FIELD (f))
1726 if (!DECL_FIELD_OFFSET (f))
1728 field_offset = byte_position (f);
1729 if (TREE_CODE (field_offset) != INTEGER_CST)
1732 /* ??? Java creates "interesting" fields for representing base classes.
1733 They have no name, and have no context. With no context, we get into
1734 trouble with nonoverlapping_component_refs_p. Skip them. */
1735 if (!DECL_FIELD_CONTEXT (f))
1738 /* The previous array field isn't at the end. */
1739 tail_array_field = NULL_TREE;
1741 /* Check to see if this offset overlaps with the field. */
1742 cmp = tree_int_cst_compare (field_offset, offset);
1746 field_type = TREE_TYPE (f);
1748 /* Here we exactly match the offset being checked. If the types match,
1749 then we can return that field. */
1751 && useless_type_conversion_p (orig_type, field_type))
1754 base = build1 (INDIRECT_REF, record_type, base);
1755 t = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE);
1759 /* Don't care about offsets into the middle of scalars. */
1760 if (!AGGREGATE_TYPE_P (field_type))
1763 /* Check for array at the end of the struct. This is often
1764 used as for flexible array members. We should be able to
1765 turn this into an array access anyway. */
1766 if (TREE_CODE (field_type) == ARRAY_TYPE)
1767 tail_array_field = f;
1769 /* Check the end of the field against the offset. */
1770 if (!DECL_SIZE_UNIT (f)
1771 || TREE_CODE (DECL_SIZE_UNIT (f)) != INTEGER_CST)
1773 t = int_const_binop (MINUS_EXPR, offset, field_offset, 1);
1774 if (!tree_int_cst_lt (t, DECL_SIZE_UNIT (f)))
1777 /* If we matched, then set offset to the displacement into
1780 new_base = build1 (INDIRECT_REF, record_type, base);
1783 new_base = build3 (COMPONENT_REF, field_type, new_base, f, NULL_TREE);
1785 /* Recurse to possibly find the match. */
1786 ret = maybe_fold_offset_to_array_ref (new_base, t, orig_type,
1787 f == TYPE_FIELDS (record_type));
1790 ret = maybe_fold_offset_to_component_ref (field_type, new_base, t,
1796 if (!tail_array_field)
1799 f = tail_array_field;
1800 field_type = TREE_TYPE (f);
1801 offset = int_const_binop (MINUS_EXPR, offset, byte_position (f), 1);
1803 /* If we get here, we've got an aggregate field, and a possibly
1804 nonzero offset into them. Recurse and hope for a valid match. */
1806 base = build1 (INDIRECT_REF, record_type, base);
1807 base = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE);
1809 t = maybe_fold_offset_to_array_ref (base, offset, orig_type,
1810 f == TYPE_FIELDS (record_type));
1813 return maybe_fold_offset_to_component_ref (field_type, base, offset,
1817 /* Attempt to express (ORIG_TYPE)BASE+OFFSET as BASE->field_of_orig_type
1818 or BASE[index] or by combination of those.
1820 Before attempting the conversion strip off existing ADDR_EXPRs and
1821 handled component refs. */
1824 maybe_fold_offset_to_reference (tree base, tree offset, tree orig_type)
1828 bool base_is_ptr = true;
1831 if (TREE_CODE (base) == ADDR_EXPR)
1833 base_is_ptr = false;
1835 base = TREE_OPERAND (base, 0);
1837 /* Handle case where existing COMPONENT_REF pick e.g. wrong field of union,
1838 so it needs to be removed and new COMPONENT_REF constructed.
1839 The wrong COMPONENT_REF are often constructed by folding the
1840 (type *)&object within the expression (type *)&object+offset */
1841 if (handled_component_p (base) && 0)
1843 HOST_WIDE_INT sub_offset, size, maxsize;
1845 newbase = get_ref_base_and_extent (base, &sub_offset,
1847 gcc_assert (newbase);
1848 gcc_assert (!(sub_offset & (BITS_PER_UNIT - 1)));
1849 if (size == maxsize)
1853 offset = int_const_binop (PLUS_EXPR, offset,
1854 build_int_cst (TREE_TYPE (offset),
1855 sub_offset / BITS_PER_UNIT), 1);
1858 if (useless_type_conversion_p (orig_type, TREE_TYPE (base))
1859 && integer_zerop (offset))
1861 type = TREE_TYPE (base);
1866 if (!POINTER_TYPE_P (TREE_TYPE (base)))
1868 type = TREE_TYPE (TREE_TYPE (base));
1870 ret = maybe_fold_offset_to_component_ref (type, base, offset,
1871 orig_type, base_is_ptr);
1875 base = build1 (INDIRECT_REF, type, base);
1876 ret = maybe_fold_offset_to_array_ref (base, offset, orig_type, true);
1881 /* A subroutine of fold_stmt_r. Attempt to simplify *(BASE+OFFSET).
1882 Return the simplified expression, or NULL if nothing could be done. */
1885 maybe_fold_stmt_indirect (tree expr, tree base, tree offset)
1888 bool volatile_p = TREE_THIS_VOLATILE (expr);
1890 /* We may well have constructed a double-nested PLUS_EXPR via multiple
1891 substitutions. Fold that down to one. Remove NON_LVALUE_EXPRs that
1892 are sometimes added. */
1894 STRIP_TYPE_NOPS (base);
1895 TREE_OPERAND (expr, 0) = base;
1897 /* One possibility is that the address reduces to a string constant. */
1898 t = fold_read_from_constant_string (expr);
1902 /* Add in any offset from a POINTER_PLUS_EXPR. */
1903 if (TREE_CODE (base) == POINTER_PLUS_EXPR)
1907 offset2 = TREE_OPERAND (base, 1);
1908 if (TREE_CODE (offset2) != INTEGER_CST)
1910 base = TREE_OPERAND (base, 0);
1912 offset = fold_convert (sizetype,
1913 int_const_binop (PLUS_EXPR, offset, offset2, 1));
1916 if (TREE_CODE (base) == ADDR_EXPR)
1918 tree base_addr = base;
1920 /* Strip the ADDR_EXPR. */
1921 base = TREE_OPERAND (base, 0);
1923 /* Fold away CONST_DECL to its value, if the type is scalar. */
1924 if (TREE_CODE (base) == CONST_DECL
1925 && is_gimple_min_invariant (DECL_INITIAL (base)))
1926 return DECL_INITIAL (base);
1928 /* Try folding *(&B+O) to B.X. */
1929 t = maybe_fold_offset_to_reference (base_addr, offset,
1933 TREE_THIS_VOLATILE (t) = volatile_p;
1939 /* We can get here for out-of-range string constant accesses,
1940 such as "_"[3]. Bail out of the entire substitution search
1941 and arrange for the entire statement to be replaced by a
1942 call to __builtin_trap. In all likelihood this will all be
1943 constant-folded away, but in the meantime we can't leave with
1944 something that get_expr_operands can't understand. */
1948 if (TREE_CODE (t) == ADDR_EXPR
1949 && TREE_CODE (TREE_OPERAND (t, 0)) == STRING_CST)
1951 /* FIXME: Except that this causes problems elsewhere with dead
1952 code not being deleted, and we die in the rtl expanders
1953 because we failed to remove some ssa_name. In the meantime,
1954 just return zero. */
1955 /* FIXME2: This condition should be signaled by
1956 fold_read_from_constant_string directly, rather than
1957 re-checking for it here. */
1958 return integer_zero_node;
1961 /* Try folding *(B+O) to B->X. Still an improvement. */
1962 if (POINTER_TYPE_P (TREE_TYPE (base)))
1964 t = maybe_fold_offset_to_reference (base, offset,
1971 /* Otherwise we had an offset that we could not simplify. */
1976 /* A subroutine of fold_stmt_r. EXPR is a POINTER_PLUS_EXPR.
1978 A quaint feature extant in our address arithmetic is that there
1979 can be hidden type changes here. The type of the result need
1980 not be the same as the type of the input pointer.
1982 What we're after here is an expression of the form
1983 (T *)(&array + const)
1984 where the cast doesn't actually exist, but is implicit in the
1985 type of the POINTER_PLUS_EXPR. We'd like to turn this into
1987 which may be able to propagate further. */
1990 maybe_fold_stmt_addition (tree expr)
1992 tree op0 = TREE_OPERAND (expr, 0);
1993 tree op1 = TREE_OPERAND (expr, 1);
1994 tree ptr_type = TREE_TYPE (expr);
1998 gcc_assert (TREE_CODE (expr) == POINTER_PLUS_EXPR);
2000 /* It had better be a constant. */
2001 if (TREE_CODE (op1) != INTEGER_CST)
2003 /* The first operand should be an ADDR_EXPR. */
2004 if (TREE_CODE (op0) != ADDR_EXPR)
2006 op0 = TREE_OPERAND (op0, 0);
2008 /* If the first operand is an ARRAY_REF, expand it so that we can fold
2009 the offset into it. */
2010 while (TREE_CODE (op0) == ARRAY_REF)
2012 tree array_obj = TREE_OPERAND (op0, 0);
2013 tree array_idx = TREE_OPERAND (op0, 1);
2014 tree elt_type = TREE_TYPE (op0);
2015 tree elt_size = TYPE_SIZE_UNIT (elt_type);
2018 if (TREE_CODE (array_idx) != INTEGER_CST)
2020 if (TREE_CODE (elt_size) != INTEGER_CST)
2023 /* Un-bias the index by the min index of the array type. */
2024 min_idx = TYPE_DOMAIN (TREE_TYPE (array_obj));
2027 min_idx = TYPE_MIN_VALUE (min_idx);
2030 if (TREE_CODE (min_idx) != INTEGER_CST)
2033 array_idx = fold_convert (TREE_TYPE (min_idx), array_idx);
2034 if (!integer_zerop (min_idx))
2035 array_idx = int_const_binop (MINUS_EXPR, array_idx,
2040 /* Convert the index to a byte offset. */
2041 array_idx = fold_convert (sizetype, array_idx);
2042 array_idx = int_const_binop (MULT_EXPR, array_idx, elt_size, 0);
2044 /* Update the operands for the next round, or for folding. */
2045 op1 = int_const_binop (PLUS_EXPR,
2050 ptd_type = TREE_TYPE (ptr_type);
2051 /* If we want a pointer to void, reconstruct the reference from the
2052 array element type. A pointer to that can be trivially converted
2053 to void *. This happens as we fold (void *)(ptr p+ off). */
2054 if (VOID_TYPE_P (ptd_type)
2055 && TREE_CODE (TREE_TYPE (op0)) == ARRAY_TYPE)
2056 ptd_type = TREE_TYPE (TREE_TYPE (op0));
2058 /* At which point we can try some of the same things as for indirects. */
2059 t = maybe_fold_offset_to_array_ref (op0, op1, ptd_type, true);
2061 t = maybe_fold_offset_to_component_ref (TREE_TYPE (op0), op0, op1,
2064 t = build1 (ADDR_EXPR, ptr_type, t);
2069 /* For passing state through walk_tree into fold_stmt_r and its
2072 struct fold_stmt_r_data
2076 bool *inside_addr_expr_p;
2079 /* Subroutine of fold_stmt called via walk_tree. We perform several
2080 simplifications of EXPR_P, mostly having to do with pointer arithmetic. */
2083 fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data)
2085 struct fold_stmt_r_data *fold_stmt_r_data = (struct fold_stmt_r_data *) data;
2086 bool *inside_addr_expr_p = fold_stmt_r_data->inside_addr_expr_p;
2087 bool *changed_p = fold_stmt_r_data->changed_p;
2088 tree expr = *expr_p, t;
2089 bool volatile_p = TREE_THIS_VOLATILE (expr);
2091 /* ??? It'd be nice if walk_tree had a pre-order option. */
2092 switch (TREE_CODE (expr))
2095 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2100 t = maybe_fold_stmt_indirect (expr, TREE_OPERAND (expr, 0),
2103 && TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR)
2104 /* If we had a good reason for propagating the address here,
2105 make sure we end up with valid gimple. See PR34989. */
2106 t = TREE_OPERAND (TREE_OPERAND (expr, 0), 0);
2110 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2115 if (POINTER_TYPE_P (TREE_TYPE (expr))
2116 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0)))
2117 && (t = maybe_fold_offset_to_reference
2118 (TREE_OPERAND (expr, 0),
2120 TREE_TYPE (TREE_TYPE (expr)))))
2122 tree ptr_type = build_pointer_type (TREE_TYPE (t));
2123 if (!useless_type_conversion_p (TREE_TYPE (expr), ptr_type))
2125 t = build_fold_addr_expr_with_type (t, ptr_type);
2129 /* ??? Could handle more ARRAY_REFs here, as a variant of INDIRECT_REF.
2130 We'd only want to bother decomposing an existing ARRAY_REF if
2131 the base array is found to have another offset contained within.
2132 Otherwise we'd be wasting time. */
2134 /* If we are not processing expressions found within an
2135 ADDR_EXPR, then we can fold constant array references. */
2136 if (!*inside_addr_expr_p)
2137 t = fold_read_from_constant_string (expr);
2143 *inside_addr_expr_p = true;
2144 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2145 *inside_addr_expr_p = false;
2150 /* Make sure the value is properly considered constant, and so gets
2151 propagated as expected. */
2153 recompute_tree_invariant_for_addr_expr (expr);
2156 case POINTER_PLUS_EXPR:
2157 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2160 t = walk_tree (&TREE_OPERAND (expr, 1), fold_stmt_r, data, NULL);
2165 t = maybe_fold_stmt_addition (expr);
2169 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2174 /* Make sure the FIELD_DECL is actually a field in the type on the lhs.
2175 We've already checked that the records are compatible, so we should
2176 come up with a set of compatible fields. */
2178 tree expr_record = TREE_TYPE (TREE_OPERAND (expr, 0));
2179 tree expr_field = TREE_OPERAND (expr, 1);
2181 if (DECL_FIELD_CONTEXT (expr_field) != TYPE_MAIN_VARIANT (expr_record))
2183 expr_field = find_compatible_field (expr_record, expr_field);
2184 TREE_OPERAND (expr, 1) = expr_field;
2189 case TARGET_MEM_REF:
2190 t = maybe_fold_tmr (expr);
2194 if (COMPARISON_CLASS_P (TREE_OPERAND (expr, 0)))
2196 tree op0 = TREE_OPERAND (expr, 0);
2200 fold_defer_overflow_warnings ();
2201 tem = fold_binary (TREE_CODE (op0), TREE_TYPE (op0),
2202 TREE_OPERAND (op0, 0),
2203 TREE_OPERAND (op0, 1));
2204 set = tem && set_rhs (expr_p, tem);
2205 fold_undefer_overflow_warnings (set, fold_stmt_r_data->stmt, 0);
2220 /* Preserve volatileness of the original expression. */
2221 TREE_THIS_VOLATILE (t) = volatile_p;
2230 /* Return the string length, maximum string length or maximum value of
2232 If ARG is an SSA name variable, follow its use-def chains. If LENGTH
2233 is not NULL and, for TYPE == 0, its value is not equal to the length
2234 we determine or if we are unable to determine the length or value,
2235 return false. VISITED is a bitmap of visited variables.
2236 TYPE is 0 if string length should be returned, 1 for maximum string
2237 length and 2 for maximum value ARG can have. */
2240 get_maxval_strlen (tree arg, tree *length, bitmap visited, int type)
2242 tree var, def_stmt, val;
2244 if (TREE_CODE (arg) != SSA_NAME)
2246 if (TREE_CODE (arg) == COND_EXPR)
2247 return get_maxval_strlen (COND_EXPR_THEN (arg), length, visited, type)
2248 && get_maxval_strlen (COND_EXPR_ELSE (arg), length, visited, type);
2249 /* We can end up with &(*iftmp_1)[0] here as well, so handle it. */
2250 else if (TREE_CODE (arg) == ADDR_EXPR
2251 && TREE_CODE (TREE_OPERAND (arg, 0)) == ARRAY_REF
2252 && integer_zerop (TREE_OPERAND (TREE_OPERAND (arg, 0), 1)))
2254 tree aop0 = TREE_OPERAND (TREE_OPERAND (arg, 0), 0);
2255 if (TREE_CODE (aop0) == INDIRECT_REF
2256 && TREE_CODE (TREE_OPERAND (aop0, 0)) == SSA_NAME)
2257 return get_maxval_strlen (TREE_OPERAND (aop0, 0),
2258 length, visited, type);
2264 if (TREE_CODE (val) != INTEGER_CST
2265 || tree_int_cst_sgn (val) < 0)
2269 val = c_strlen (arg, 1);
2277 if (TREE_CODE (*length) != INTEGER_CST
2278 || TREE_CODE (val) != INTEGER_CST)
2281 if (tree_int_cst_lt (*length, val))
2285 else if (simple_cst_equal (val, *length) != 1)
2293 /* If we were already here, break the infinite cycle. */
2294 if (bitmap_bit_p (visited, SSA_NAME_VERSION (arg)))
2296 bitmap_set_bit (visited, SSA_NAME_VERSION (arg));
2299 def_stmt = SSA_NAME_DEF_STMT (var);
2301 switch (TREE_CODE (def_stmt))
2303 case GIMPLE_MODIFY_STMT:
2307 /* The RHS of the statement defining VAR must either have a
2308 constant length or come from another SSA_NAME with a constant
2310 rhs = GIMPLE_STMT_OPERAND (def_stmt, 1);
2312 return get_maxval_strlen (rhs, length, visited, type);
2317 /* All the arguments of the PHI node must have the same constant
2321 for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++)
2323 tree arg = PHI_ARG_DEF (def_stmt, i);
2325 /* If this PHI has itself as an argument, we cannot
2326 determine the string length of this argument. However,
2327 if we can find a constant string length for the other
2328 PHI args then we can still be sure that this is a
2329 constant string length. So be optimistic and just
2330 continue with the next argument. */
2331 if (arg == PHI_RESULT (def_stmt))
2334 if (!get_maxval_strlen (arg, length, visited, type))
2350 /* Fold builtin call FN in statement STMT. If it cannot be folded into a
2351 constant, return NULL_TREE. Otherwise, return its constant value. */
2354 ccp_fold_builtin (tree stmt, tree fn)
2356 tree result, val[3];
2358 int arg_mask, i, type;
2361 call_expr_arg_iterator iter;
2364 ignore = TREE_CODE (stmt) != GIMPLE_MODIFY_STMT;
2366 /* First try the generic builtin folder. If that succeeds, return the
2368 result = fold_call_expr (fn, ignore);
2372 STRIP_NOPS (result);
2376 /* Ignore MD builtins. */
2377 callee = get_callee_fndecl (fn);
2378 if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_MD)
2381 /* If the builtin could not be folded, and it has no argument list,
2383 nargs = call_expr_nargs (fn);
2387 /* Limit the work only for builtins we know how to simplify. */
2388 switch (DECL_FUNCTION_CODE (callee))
2390 case BUILT_IN_STRLEN:
2391 case BUILT_IN_FPUTS:
2392 case BUILT_IN_FPUTS_UNLOCKED:
2396 case BUILT_IN_STRCPY:
2397 case BUILT_IN_STRNCPY:
2401 case BUILT_IN_MEMCPY_CHK:
2402 case BUILT_IN_MEMPCPY_CHK:
2403 case BUILT_IN_MEMMOVE_CHK:
2404 case BUILT_IN_MEMSET_CHK:
2405 case BUILT_IN_STRNCPY_CHK:
2409 case BUILT_IN_STRCPY_CHK:
2410 case BUILT_IN_STPCPY_CHK:
2414 case BUILT_IN_SNPRINTF_CHK:
2415 case BUILT_IN_VSNPRINTF_CHK:
2423 /* Try to use the dataflow information gathered by the CCP process. */
2424 visited = BITMAP_ALLOC (NULL);
2426 memset (val, 0, sizeof (val));
2427 init_call_expr_arg_iterator (fn, &iter);
2428 for (i = 0; arg_mask; i++, arg_mask >>= 1)
2430 a = next_call_expr_arg (&iter);
2433 bitmap_clear (visited);
2434 if (!get_maxval_strlen (a, &val[i], visited, type))
2439 BITMAP_FREE (visited);
2442 switch (DECL_FUNCTION_CODE (callee))
2444 case BUILT_IN_STRLEN:
2447 tree new_val = fold_convert (TREE_TYPE (fn), val[0]);
2449 /* If the result is not a valid gimple value, or not a cast
2450 of a valid gimple value, then we can not use the result. */
2451 if (is_gimple_val (new_val)
2452 || (is_gimple_cast (new_val)
2453 && is_gimple_val (TREE_OPERAND (new_val, 0))))
2458 case BUILT_IN_STRCPY:
2459 if (val[1] && is_gimple_val (val[1]) && nargs == 2)
2460 result = fold_builtin_strcpy (callee,
2461 CALL_EXPR_ARG (fn, 0),
2462 CALL_EXPR_ARG (fn, 1),
2466 case BUILT_IN_STRNCPY:
2467 if (val[1] && is_gimple_val (val[1]) && nargs == 3)
2468 result = fold_builtin_strncpy (callee,
2469 CALL_EXPR_ARG (fn, 0),
2470 CALL_EXPR_ARG (fn, 1),
2471 CALL_EXPR_ARG (fn, 2),
2475 case BUILT_IN_FPUTS:
2476 result = fold_builtin_fputs (CALL_EXPR_ARG (fn, 0),
2477 CALL_EXPR_ARG (fn, 1),
2478 TREE_CODE (stmt) != GIMPLE_MODIFY_STMT, 0,
2482 case BUILT_IN_FPUTS_UNLOCKED:
2483 result = fold_builtin_fputs (CALL_EXPR_ARG (fn, 0),
2484 CALL_EXPR_ARG (fn, 1),
2485 TREE_CODE (stmt) != GIMPLE_MODIFY_STMT, 1,
2489 case BUILT_IN_MEMCPY_CHK:
2490 case BUILT_IN_MEMPCPY_CHK:
2491 case BUILT_IN_MEMMOVE_CHK:
2492 case BUILT_IN_MEMSET_CHK:
2493 if (val[2] && is_gimple_val (val[2]))
2494 result = fold_builtin_memory_chk (callee,
2495 CALL_EXPR_ARG (fn, 0),
2496 CALL_EXPR_ARG (fn, 1),
2497 CALL_EXPR_ARG (fn, 2),
2498 CALL_EXPR_ARG (fn, 3),
2500 DECL_FUNCTION_CODE (callee));
2503 case BUILT_IN_STRCPY_CHK:
2504 case BUILT_IN_STPCPY_CHK:
2505 if (val[1] && is_gimple_val (val[1]))
2506 result = fold_builtin_stxcpy_chk (callee,
2507 CALL_EXPR_ARG (fn, 0),
2508 CALL_EXPR_ARG (fn, 1),
2509 CALL_EXPR_ARG (fn, 2),
2511 DECL_FUNCTION_CODE (callee));
2514 case BUILT_IN_STRNCPY_CHK:
2515 if (val[2] && is_gimple_val (val[2]))
2516 result = fold_builtin_strncpy_chk (CALL_EXPR_ARG (fn, 0),
2517 CALL_EXPR_ARG (fn, 1),
2518 CALL_EXPR_ARG (fn, 2),
2519 CALL_EXPR_ARG (fn, 3),
2523 case BUILT_IN_SNPRINTF_CHK:
2524 case BUILT_IN_VSNPRINTF_CHK:
2525 if (val[1] && is_gimple_val (val[1]))
2526 result = fold_builtin_snprintf_chk (fn, val[1],
2527 DECL_FUNCTION_CODE (callee));
2534 if (result && ignore)
2535 result = fold_ignored_result (result);
2540 /* Fold the statement pointed to by STMT_P. In some cases, this function may
2541 replace the whole statement with a new one. Returns true iff folding
2542 makes any changes. */
2545 fold_stmt (tree *stmt_p)
2547 tree rhs, result, stmt;
2548 struct fold_stmt_r_data fold_stmt_r_data;
2549 bool changed = false;
2550 bool inside_addr_expr = false;
2554 fold_stmt_r_data.stmt = stmt;
2555 fold_stmt_r_data.changed_p = &changed;
2556 fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr;
2558 /* If we replaced constants and the statement makes pointer dereferences,
2559 then we may need to fold instances of *&VAR into VAR, etc. */
2560 if (walk_tree (stmt_p, fold_stmt_r, &fold_stmt_r_data, NULL))
2562 *stmt_p = build_call_expr (implicit_built_in_decls[BUILT_IN_TRAP], 0);
2566 rhs = get_rhs (stmt);
2571 if (TREE_CODE (rhs) == CALL_EXPR)
2575 /* Check for builtins that CCP can handle using information not
2576 available in the generic fold routines. */
2577 callee = get_callee_fndecl (rhs);
2578 if (callee && DECL_BUILT_IN (callee))
2579 result = ccp_fold_builtin (stmt, rhs);
2582 /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve
2583 here are when we've propagated the address of a decl into the
2585 /* ??? Should perhaps do this in fold proper. However, doing it
2586 there requires that we create a new CALL_EXPR, and that requires
2587 copying EH region info to the new node. Easier to just do it
2588 here where we can just smash the call operand. Also
2589 CALL_EXPR_RETURN_SLOT_OPT needs to be handled correctly and
2590 copied, fold_call_expr does not have not information. */
2591 callee = CALL_EXPR_FN (rhs);
2592 if (TREE_CODE (callee) == OBJ_TYPE_REF
2593 && lang_hooks.fold_obj_type_ref
2594 && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee)) == ADDR_EXPR
2595 && DECL_P (TREE_OPERAND
2596 (OBJ_TYPE_REF_OBJECT (callee), 0)))
2600 /* ??? Caution: Broken ADDR_EXPR semantics means that
2601 looking at the type of the operand of the addr_expr
2602 can yield an array type. See silly exception in
2603 check_pointer_types_r. */
2605 t = TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee)));
2606 t = lang_hooks.fold_obj_type_ref (callee, t);
2609 CALL_EXPR_FN (rhs) = t;
2615 else if (TREE_CODE (rhs) == COND_EXPR)
2617 tree temp = fold (COND_EXPR_COND (rhs));
2618 if (temp != COND_EXPR_COND (rhs))
2619 result = fold_build3 (COND_EXPR, TREE_TYPE (rhs), temp,
2620 COND_EXPR_THEN (rhs), COND_EXPR_ELSE (rhs));
2623 /* If we couldn't fold the RHS, hand over to the generic fold routines. */
2624 if (result == NULL_TREE)
2625 result = fold (rhs);
2627 /* Strip away useless type conversions. Both the NON_LVALUE_EXPR that
2628 may have been added by fold, and "useless" type conversions that might
2629 now be apparent due to propagation. */
2630 STRIP_USELESS_TYPE_CONVERSION (result);
2633 changed |= set_rhs (stmt_p, result);
2638 /* Perform the minimal folding on statement STMT. Only operations like
2639 *&x created by constant propagation are handled. The statement cannot
2640 be replaced with a new one. */
2643 fold_stmt_inplace (tree stmt)
2645 tree old_stmt = stmt, rhs, new_rhs;
2646 struct fold_stmt_r_data fold_stmt_r_data;
2647 bool changed = false;
2648 bool inside_addr_expr = false;
2650 fold_stmt_r_data.stmt = stmt;
2651 fold_stmt_r_data.changed_p = &changed;
2652 fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr;
2654 walk_tree (&stmt, fold_stmt_r, &fold_stmt_r_data, NULL);
2655 gcc_assert (stmt == old_stmt);
2657 rhs = get_rhs (stmt);
2658 if (!rhs || rhs == stmt)
2661 new_rhs = fold (rhs);
2662 STRIP_USELESS_TYPE_CONVERSION (new_rhs);
2666 changed |= set_rhs (&stmt, new_rhs);
2667 gcc_assert (stmt == old_stmt);
2672 /* Try to optimize out __builtin_stack_restore. Optimize it out
2673 if there is another __builtin_stack_restore in the same basic
2674 block and no calls or ASM_EXPRs are in between, or if this block's
2675 only outgoing edge is to EXIT_BLOCK and there are no calls or
2676 ASM_EXPRs after this __builtin_stack_restore. */
2679 optimize_stack_restore (basic_block bb, tree call, block_stmt_iterator i)
2681 tree stack_save, stmt, callee;
2683 if (TREE_CODE (call) != CALL_EXPR
2684 || call_expr_nargs (call) != 1
2685 || TREE_CODE (CALL_EXPR_ARG (call, 0)) != SSA_NAME
2686 || !POINTER_TYPE_P (TREE_TYPE (CALL_EXPR_ARG (call, 0))))
2689 for (bsi_next (&i); !bsi_end_p (i); bsi_next (&i))
2693 stmt = bsi_stmt (i);
2694 if (TREE_CODE (stmt) == ASM_EXPR)
2696 call = get_call_expr_in (stmt);
2700 callee = get_callee_fndecl (call);
2701 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
2704 if (DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_RESTORE)
2709 && (! single_succ_p (bb)
2710 || single_succ_edge (bb)->dest != EXIT_BLOCK_PTR))
2713 stack_save = SSA_NAME_DEF_STMT (CALL_EXPR_ARG (call, 0));
2714 if (TREE_CODE (stack_save) != GIMPLE_MODIFY_STMT
2715 || GIMPLE_STMT_OPERAND (stack_save, 0) != CALL_EXPR_ARG (call, 0)
2716 || TREE_CODE (GIMPLE_STMT_OPERAND (stack_save, 1)) != CALL_EXPR
2717 || tree_could_throw_p (stack_save)
2718 || !has_single_use (CALL_EXPR_ARG (call, 0)))
2721 callee = get_callee_fndecl (GIMPLE_STMT_OPERAND (stack_save, 1));
2723 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
2724 || DECL_FUNCTION_CODE (callee) != BUILT_IN_STACK_SAVE
2725 || call_expr_nargs (GIMPLE_STMT_OPERAND (stack_save, 1)) != 0)
2729 push_stmt_changes (&stmt);
2730 if (!set_rhs (&stmt,
2731 build_int_cst (TREE_TYPE (CALL_EXPR_ARG (call, 0)), 0)))
2733 discard_stmt_changes (&stmt);
2736 gcc_assert (stmt == stack_save);
2737 pop_stmt_changes (&stmt);
2739 return integer_zero_node;
2742 /* If va_list type is a simple pointer and nothing special is needed,
2743 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
2744 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
2745 pointer assignment. */
2748 optimize_stdarg_builtin (tree call)
2750 tree callee, lhs, rhs;
2751 bool va_list_simple_ptr;
2753 if (TREE_CODE (call) != CALL_EXPR)
2756 va_list_simple_ptr = POINTER_TYPE_P (va_list_type_node)
2757 && (TREE_TYPE (va_list_type_node) == void_type_node
2758 || TREE_TYPE (va_list_type_node) == char_type_node);
2760 callee = get_callee_fndecl (call);
2761 switch (DECL_FUNCTION_CODE (callee))
2763 case BUILT_IN_VA_START:
2764 if (!va_list_simple_ptr
2765 || targetm.expand_builtin_va_start != NULL
2766 || built_in_decls[BUILT_IN_NEXT_ARG] == NULL)
2769 if (call_expr_nargs (call) != 2)
2772 lhs = CALL_EXPR_ARG (call, 0);
2773 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
2774 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
2775 != TYPE_MAIN_VARIANT (va_list_type_node))
2778 lhs = build_fold_indirect_ref (lhs);
2779 rhs = build_call_expr (built_in_decls[BUILT_IN_NEXT_ARG],
2780 1, integer_zero_node);
2781 rhs = fold_convert (TREE_TYPE (lhs), rhs);
2782 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
2784 case BUILT_IN_VA_COPY:
2785 if (!va_list_simple_ptr)
2788 if (call_expr_nargs (call) != 2)
2791 lhs = CALL_EXPR_ARG (call, 0);
2792 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
2793 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
2794 != TYPE_MAIN_VARIANT (va_list_type_node))
2797 lhs = build_fold_indirect_ref (lhs);
2798 rhs = CALL_EXPR_ARG (call, 1);
2799 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs))
2800 != TYPE_MAIN_VARIANT (va_list_type_node))
2803 rhs = fold_convert (TREE_TYPE (lhs), rhs);
2804 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
2806 case BUILT_IN_VA_END:
2807 return integer_zero_node;
2814 /* Convert EXPR into a GIMPLE value suitable for substitution on the
2815 RHS of an assignment. Insert the necessary statements before
2817 When IGNORE is set, don't worry about the return value. */
2820 convert_to_gimple_builtin (block_stmt_iterator *si_p, tree expr, bool ignore)
2822 tree_stmt_iterator ti;
2823 tree stmt = bsi_stmt (*si_p);
2824 tree tmp, stmts = NULL;
2826 push_gimplify_context ();
2829 tmp = build_empty_stmt ();
2830 gimplify_and_add (expr, &stmts);
2833 tmp = get_initialized_tmp_var (expr, &stmts, NULL);
2834 pop_gimplify_context (NULL);
2836 if (EXPR_HAS_LOCATION (stmt))
2837 annotate_all_with_locus (&stmts, EXPR_LOCATION (stmt));
2839 /* The replacement can expose previously unreferenced variables. */
2840 for (ti = tsi_start (stmts); !tsi_end_p (ti); tsi_next (&ti))
2842 tree new_stmt = tsi_stmt (ti);
2843 find_new_referenced_vars (tsi_stmt_ptr (ti));
2844 bsi_insert_before (si_p, new_stmt, BSI_NEW_STMT);
2845 mark_symbols_for_renaming (new_stmt);
2853 /* A simple pass that attempts to fold all builtin functions. This pass
2854 is run after we've propagated as many constants as we can. */
2857 execute_fold_all_builtins (void)
2859 bool cfg_changed = false;
2861 unsigned int todoflags = 0;
2865 block_stmt_iterator i;
2866 for (i = bsi_start (bb); !bsi_end_p (i); )
2868 tree *stmtp = bsi_stmt_ptr (i);
2869 tree old_stmt = *stmtp;
2870 tree call = get_rhs (*stmtp);
2871 tree callee, result;
2872 enum built_in_function fcode;
2874 if (!call || TREE_CODE (call) != CALL_EXPR)
2879 callee = get_callee_fndecl (call);
2880 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
2885 fcode = DECL_FUNCTION_CODE (callee);
2887 result = ccp_fold_builtin (*stmtp, call);
2889 switch (DECL_FUNCTION_CODE (callee))
2891 case BUILT_IN_CONSTANT_P:
2892 /* Resolve __builtin_constant_p. If it hasn't been
2893 folded to integer_one_node by now, it's fairly
2894 certain that the value simply isn't constant. */
2895 result = integer_zero_node;
2898 case BUILT_IN_STACK_RESTORE:
2899 result = optimize_stack_restore (bb, *stmtp, i);
2905 case BUILT_IN_VA_START:
2906 case BUILT_IN_VA_END:
2907 case BUILT_IN_VA_COPY:
2908 /* These shouldn't be folded before pass_stdarg. */
2909 result = optimize_stdarg_builtin (*stmtp);
2919 if (dump_file && (dump_flags & TDF_DETAILS))
2921 fprintf (dump_file, "Simplified\n ");
2922 print_generic_stmt (dump_file, *stmtp, dump_flags);
2925 push_stmt_changes (stmtp);
2927 if (!set_rhs (stmtp, result))
2929 result = convert_to_gimple_builtin (&i, result,
2930 TREE_CODE (old_stmt)
2931 != GIMPLE_MODIFY_STMT);
2934 bool ok = set_rhs (stmtp, result);
2936 todoflags |= TODO_rebuild_alias;
2940 pop_stmt_changes (stmtp);
2942 if (maybe_clean_or_replace_eh_stmt (old_stmt, *stmtp)
2943 && tree_purge_dead_eh_edges (bb))
2946 if (dump_file && (dump_flags & TDF_DETAILS))
2948 fprintf (dump_file, "to\n ");
2949 print_generic_stmt (dump_file, *stmtp, dump_flags);
2950 fprintf (dump_file, "\n");
2953 /* Retry the same statement if it changed into another
2954 builtin, there might be new opportunities now. */
2955 call = get_rhs (*stmtp);
2956 if (!call || TREE_CODE (call) != CALL_EXPR)
2961 callee = get_callee_fndecl (call);
2963 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
2964 || DECL_FUNCTION_CODE (callee) == fcode)
2969 /* Delete unreachable blocks. */
2971 todoflags |= TODO_cleanup_cfg;
2977 struct gimple_opt_pass pass_fold_builtins =
2983 execute_fold_all_builtins, /* execute */
2986 0, /* static_pass_number */
2988 PROP_cfg | PROP_ssa, /* properties_required */
2989 0, /* properties_provided */
2990 0, /* properties_destroyed */
2991 0, /* todo_flags_start */
2994 | TODO_update_ssa /* todo_flags_finish */