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 /* The regular is_gimple_min_invariant does a shallow test of the object.
271 It assumes that full gimplification has happened, or will happen on the
272 object. For a value coming from DECL_INITIAL, this is not true, so we
273 have to be more strict ourselves. */
276 ccp_decl_initial_min_invariant (tree t)
278 if (!is_gimple_min_invariant (t))
280 if (TREE_CODE (t) == ADDR_EXPR)
282 /* Inline and unroll is_gimple_addressable. */
285 t = TREE_OPERAND (t, 0);
286 if (is_gimple_id (t))
288 if (!handled_component_p (t))
295 /* If SYM is a constant variable with known value, return the value.
296 NULL_TREE is returned otherwise. */
299 get_symbol_constant_value (tree sym)
301 if (TREE_STATIC (sym)
302 && TREE_READONLY (sym)
305 tree val = DECL_INITIAL (sym);
307 && ccp_decl_initial_min_invariant (val))
309 /* Variables declared 'const' without an initializer
310 have zero as the intializer. */
312 && (INTEGRAL_TYPE_P (TREE_TYPE (sym))
313 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (sym))))
314 return fold_convert (TREE_TYPE (sym), integer_zero_node);
320 /* Compute a default value for variable VAR and store it in the
321 CONST_VAL array. The following rules are used to get default
324 1- Global and static variables that are declared constant are
327 2- Any other value is considered UNDEFINED. This is useful when
328 considering PHI nodes. PHI arguments that are undefined do not
329 change the constant value of the PHI node, which allows for more
330 constants to be propagated.
332 3- If SSA_NAME_VALUE is set and it is a constant, its value is
335 4- Variables defined by statements other than assignments and PHI
336 nodes are considered VARYING.
338 5- Initial values of variables that are not GIMPLE registers are
339 considered VARYING. */
342 get_default_value (tree var)
344 tree sym = SSA_NAME_VAR (var);
345 prop_value_t val = { UNINITIALIZED, NULL_TREE, NULL_TREE };
348 if (!do_store_ccp && !is_gimple_reg (var))
350 /* Short circuit for regular CCP. We are not interested in any
351 non-register when DO_STORE_CCP is false. */
352 val.lattice_val = VARYING;
354 else if (SSA_NAME_VALUE (var)
355 && is_gimple_min_invariant (SSA_NAME_VALUE (var)))
357 val.lattice_val = CONSTANT;
358 val.value = SSA_NAME_VALUE (var);
360 else if ((cst_val = get_symbol_constant_value (sym)) != NULL_TREE)
362 /* Globals and static variables declared 'const' take their
364 val.lattice_val = CONSTANT;
370 tree stmt = SSA_NAME_DEF_STMT (var);
372 if (IS_EMPTY_STMT (stmt))
374 /* Variables defined by an empty statement are those used
375 before being initialized. If VAR is a local variable, we
376 can assume initially that it is UNDEFINED, otherwise we must
377 consider it VARYING. */
378 if (is_gimple_reg (sym) && TREE_CODE (sym) != PARM_DECL)
379 val.lattice_val = UNDEFINED;
381 val.lattice_val = VARYING;
383 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
384 || TREE_CODE (stmt) == PHI_NODE)
386 /* Any other variable defined by an assignment or a PHI node
387 is considered UNDEFINED. */
388 val.lattice_val = UNDEFINED;
392 /* Otherwise, VAR will never take on a constant value. */
393 val.lattice_val = VARYING;
401 /* Get the constant value associated with variable VAR. */
403 static inline prop_value_t *
406 prop_value_t *val = &const_val[SSA_NAME_VERSION (var)];
408 if (val->lattice_val == UNINITIALIZED)
409 *val = get_default_value (var);
414 /* Sets the value associated with VAR to VARYING. */
417 set_value_varying (tree var)
419 prop_value_t *val = &const_val[SSA_NAME_VERSION (var)];
421 val->lattice_val = VARYING;
422 val->value = NULL_TREE;
423 val->mem_ref = NULL_TREE;
426 /* For float types, modify the value of VAL to make ccp work correctly
427 for non-standard values (-0, NaN):
429 If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0.
430 If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED.
431 This is to fix the following problem (see PR 29921): Suppose we have
435 and we set value of y to NaN. This causes value of x to be set to NaN.
436 When we later determine that y is in fact VARYING, fold uses the fact
437 that HONOR_NANS is false, and we try to change the value of x to 0,
438 causing an ICE. With HONOR_NANS being false, the real appearance of
439 NaN would cause undefined behavior, though, so claiming that y (and x)
440 are UNDEFINED initially is correct. */
443 canonicalize_float_value (prop_value_t *val)
445 enum machine_mode mode;
449 if (val->lattice_val != CONSTANT
450 || TREE_CODE (val->value) != REAL_CST)
453 d = TREE_REAL_CST (val->value);
454 type = TREE_TYPE (val->value);
455 mode = TYPE_MODE (type);
457 if (!HONOR_SIGNED_ZEROS (mode)
458 && REAL_VALUE_MINUS_ZERO (d))
460 val->value = build_real (type, dconst0);
464 if (!HONOR_NANS (mode)
465 && REAL_VALUE_ISNAN (d))
467 val->lattice_val = UNDEFINED;
474 /* Set the value for variable VAR to NEW_VAL. Return true if the new
475 value is different from VAR's previous value. */
478 set_lattice_value (tree var, prop_value_t new_val)
480 prop_value_t *old_val = get_value (var);
482 canonicalize_float_value (&new_val);
484 /* Lattice transitions must always be monotonically increasing in
485 value. If *OLD_VAL and NEW_VAL are the same, return false to
486 inform the caller that this was a non-transition. */
488 gcc_assert (old_val->lattice_val < new_val.lattice_val
489 || (old_val->lattice_val == new_val.lattice_val
490 && ((!old_val->value && !new_val.value)
491 || operand_equal_p (old_val->value, new_val.value, 0))
492 && old_val->mem_ref == new_val.mem_ref));
494 if (old_val->lattice_val != new_val.lattice_val)
496 if (dump_file && (dump_flags & TDF_DETAILS))
498 dump_lattice_value (dump_file, "Lattice value changed to ", new_val);
499 fprintf (dump_file, ". Adding SSA edges to worklist.\n");
504 gcc_assert (new_val.lattice_val != UNDEFINED);
512 /* Return the likely CCP lattice value for STMT.
514 If STMT has no operands, then return CONSTANT.
516 Else if undefinedness of operands of STMT cause its value to be
517 undefined, then return UNDEFINED.
519 Else if any operands of STMT are constants, then return CONSTANT.
521 Else return VARYING. */
524 likely_value (tree stmt)
526 bool has_constant_operand, has_undefined_operand, all_undefined_operands;
531 ann = stmt_ann (stmt);
533 /* If the statement has volatile operands, it won't fold to a
535 if (ann->has_volatile_ops)
538 /* If we are not doing store-ccp, statements with loads
539 and/or stores will never fold into a constant. */
541 && !ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
545 /* A CALL_EXPR is assumed to be varying. NOTE: This may be overly
546 conservative, in the presence of const and pure calls. */
547 if (get_call_expr_in (stmt) != NULL_TREE)
550 /* Anything other than assignments and conditional jumps are not
551 interesting for CCP. */
552 if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT
553 && !(TREE_CODE (stmt) == RETURN_EXPR && get_rhs (stmt) != NULL_TREE)
554 && TREE_CODE (stmt) != COND_EXPR
555 && TREE_CODE (stmt) != SWITCH_EXPR)
558 if (is_gimple_min_invariant (get_rhs (stmt)))
561 has_constant_operand = false;
562 has_undefined_operand = false;
563 all_undefined_operands = true;
564 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
566 prop_value_t *val = get_value (use);
568 if (val->lattice_val == UNDEFINED)
569 has_undefined_operand = true;
571 all_undefined_operands = false;
573 if (val->lattice_val == CONSTANT)
574 has_constant_operand = true;
577 /* If the operation combines operands like COMPLEX_EXPR make sure to
578 not mark the result UNDEFINED if only one part of the result is
580 if (has_undefined_operand
581 && all_undefined_operands)
583 else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
584 && has_undefined_operand)
586 switch (TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)))
588 /* Unary operators are handled with all_undefined_operands. */
591 case POINTER_PLUS_EXPR:
592 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected.
593 Not bitwise operators, one VARYING operand may specify the
594 result completely. Not logical operators for the same reason.
595 Not COMPLEX_EXPR as one VARYING operand makes the result partly
596 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because
597 the undefined operand may be promoted. */
604 /* If there was an UNDEFINED operand but the result may be not UNDEFINED
605 fall back to VARYING even if there were CONSTANT operands. */
606 if (has_undefined_operand)
609 if (has_constant_operand
610 /* We do not consider virtual operands here -- load from read-only
611 memory may have only VARYING virtual operands, but still be
613 || ZERO_SSA_OPERANDS (stmt, SSA_OP_USE))
619 /* Returns true if STMT cannot be constant. */
622 surely_varying_stmt_p (tree stmt)
624 /* If the statement has operands that we cannot handle, it cannot be
626 if (stmt_ann (stmt)->has_volatile_ops)
629 if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
634 /* We can only handle simple loads and stores. */
635 if (!stmt_makes_single_load (stmt)
636 && !stmt_makes_single_store (stmt))
640 /* If it contains a call, it is varying. */
641 if (get_call_expr_in (stmt) != NULL_TREE)
644 /* Anything other than assignments and conditional jumps are not
645 interesting for CCP. */
646 if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT
647 && !(TREE_CODE (stmt) == RETURN_EXPR && get_rhs (stmt) != NULL_TREE)
648 && TREE_CODE (stmt) != COND_EXPR
649 && TREE_CODE (stmt) != SWITCH_EXPR)
655 /* Initialize local data structures for CCP. */
658 ccp_initialize (void)
662 const_val = XCNEWVEC (prop_value_t, num_ssa_names);
664 /* Initialize simulation flags for PHI nodes and statements. */
667 block_stmt_iterator i;
669 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
671 tree stmt = bsi_stmt (i);
672 bool is_varying = surely_varying_stmt_p (stmt);
679 /* If the statement will not produce a constant, mark
680 all its outputs VARYING. */
681 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
684 set_value_varying (def);
688 DONT_SIMULATE_AGAIN (stmt) = is_varying;
692 /* Now process PHI nodes. We never set DONT_SIMULATE_AGAIN on phi node,
693 since we do not know which edges are executable yet, except for
694 phi nodes for virtual operands when we do not do store ccp. */
699 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
701 if (!do_store_ccp && !is_gimple_reg (PHI_RESULT (phi)))
702 DONT_SIMULATE_AGAIN (phi) = true;
704 DONT_SIMULATE_AGAIN (phi) = false;
710 /* Do final substitution of propagated values, cleanup the flowgraph and
711 free allocated storage.
713 Return TRUE when something was optimized. */
718 /* Perform substitutions based on the known constant values. */
719 bool something_changed = substitute_and_fold (const_val, false);
722 return something_changed;;
726 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
729 any M UNDEFINED = any
730 any M VARYING = VARYING
731 Ci M Cj = Ci if (i == j)
732 Ci M Cj = VARYING if (i != j)
736 ccp_lattice_meet (prop_value_t *val1, prop_value_t *val2)
738 if (val1->lattice_val == UNDEFINED)
740 /* UNDEFINED M any = any */
743 else if (val2->lattice_val == UNDEFINED)
745 /* any M UNDEFINED = any
746 Nothing to do. VAL1 already contains the value we want. */
749 else if (val1->lattice_val == VARYING
750 || val2->lattice_val == VARYING)
752 /* any M VARYING = VARYING. */
753 val1->lattice_val = VARYING;
754 val1->value = NULL_TREE;
755 val1->mem_ref = NULL_TREE;
757 else if (val1->lattice_val == CONSTANT
758 && val2->lattice_val == CONSTANT
759 && simple_cst_equal (val1->value, val2->value) == 1
761 || (val1->mem_ref && val2->mem_ref
762 && operand_equal_p (val1->mem_ref, val2->mem_ref, 0))))
764 /* Ci M Cj = Ci if (i == j)
765 Ci M Cj = VARYING if (i != j)
767 If these two values come from memory stores, make sure that
768 they come from the same memory reference. */
769 val1->lattice_val = CONSTANT;
770 val1->value = val1->value;
771 val1->mem_ref = val1->mem_ref;
775 /* Any other combination is VARYING. */
776 val1->lattice_val = VARYING;
777 val1->value = NULL_TREE;
778 val1->mem_ref = NULL_TREE;
783 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
784 lattice values to determine PHI_NODE's lattice value. The value of a
785 PHI node is determined calling ccp_lattice_meet with all the arguments
786 of the PHI node that are incoming via executable edges. */
788 static enum ssa_prop_result
789 ccp_visit_phi_node (tree phi)
792 prop_value_t *old_val, new_val;
794 if (dump_file && (dump_flags & TDF_DETAILS))
796 fprintf (dump_file, "\nVisiting PHI node: ");
797 print_generic_expr (dump_file, phi, dump_flags);
800 old_val = get_value (PHI_RESULT (phi));
801 switch (old_val->lattice_val)
804 return SSA_PROP_VARYING;
811 new_val.lattice_val = UNDEFINED;
812 new_val.value = NULL_TREE;
813 new_val.mem_ref = NULL_TREE;
820 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
822 /* Compute the meet operator over all the PHI arguments flowing
823 through executable edges. */
824 edge e = PHI_ARG_EDGE (phi, i);
826 if (dump_file && (dump_flags & TDF_DETAILS))
829 "\n Argument #%d (%d -> %d %sexecutable)\n",
830 i, e->src->index, e->dest->index,
831 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
834 /* If the incoming edge is executable, Compute the meet operator for
835 the existing value of the PHI node and the current PHI argument. */
836 if (e->flags & EDGE_EXECUTABLE)
838 tree arg = PHI_ARG_DEF (phi, i);
839 prop_value_t arg_val;
841 if (is_gimple_min_invariant (arg))
843 arg_val.lattice_val = CONSTANT;
845 arg_val.mem_ref = NULL_TREE;
848 arg_val = *(get_value (arg));
850 ccp_lattice_meet (&new_val, &arg_val);
852 if (dump_file && (dump_flags & TDF_DETAILS))
854 fprintf (dump_file, "\t");
855 print_generic_expr (dump_file, arg, dump_flags);
856 dump_lattice_value (dump_file, "\tValue: ", arg_val);
857 fprintf (dump_file, "\n");
860 if (new_val.lattice_val == VARYING)
865 if (dump_file && (dump_flags & TDF_DETAILS))
867 dump_lattice_value (dump_file, "\n PHI node value: ", new_val);
868 fprintf (dump_file, "\n\n");
871 /* Make the transition to the new value. */
872 if (set_lattice_value (PHI_RESULT (phi), new_val))
874 if (new_val.lattice_val == VARYING)
875 return SSA_PROP_VARYING;
877 return SSA_PROP_INTERESTING;
880 return SSA_PROP_NOT_INTERESTING;
884 /* CCP specific front-end to the non-destructive constant folding
887 Attempt to simplify the RHS of STMT knowing that one or more
888 operands are constants.
890 If simplification is possible, return the simplified RHS,
891 otherwise return the original RHS. */
896 tree rhs = get_rhs (stmt);
897 enum tree_code code = TREE_CODE (rhs);
898 enum tree_code_class kind = TREE_CODE_CLASS (code);
899 tree retval = NULL_TREE;
901 if (TREE_CODE (rhs) == SSA_NAME)
903 /* If the RHS is an SSA_NAME, return its known constant value,
905 return get_value (rhs)->value;
907 else if (do_store_ccp && stmt_makes_single_load (stmt))
909 /* If the RHS is a memory load, see if the VUSEs associated with
910 it are a valid constant for that memory load. */
911 prop_value_t *val = get_value_loaded_by (stmt, const_val);
912 if (val && val->mem_ref)
914 if (operand_equal_p (val->mem_ref, rhs, 0))
917 /* If RHS is extracting REALPART_EXPR or IMAGPART_EXPR of a
918 complex type with a known constant value, return it. */
919 if ((TREE_CODE (rhs) == REALPART_EXPR
920 || TREE_CODE (rhs) == IMAGPART_EXPR)
921 && operand_equal_p (val->mem_ref, TREE_OPERAND (rhs, 0), 0))
922 return fold_build1 (TREE_CODE (rhs), TREE_TYPE (rhs), val->value);
927 /* Unary operators. Note that we know the single operand must
928 be a constant. So this should almost always return a
930 if (kind == tcc_unary)
932 /* Handle unary operators which can appear in GIMPLE form. */
933 tree op0 = TREE_OPERAND (rhs, 0);
935 /* Simplify the operand down to a constant. */
936 if (TREE_CODE (op0) == SSA_NAME)
938 prop_value_t *val = get_value (op0);
939 if (val->lattice_val == CONSTANT)
940 op0 = get_value (op0)->value;
943 if ((code == NOP_EXPR || code == CONVERT_EXPR)
944 && useless_type_conversion_p (TREE_TYPE (rhs), TREE_TYPE (op0)))
946 return fold_unary (code, TREE_TYPE (rhs), op0);
949 /* Binary and comparison operators. We know one or both of the
950 operands are constants. */
951 else if (kind == tcc_binary
952 || kind == tcc_comparison
953 || code == TRUTH_AND_EXPR
954 || code == TRUTH_OR_EXPR
955 || code == TRUTH_XOR_EXPR)
957 /* Handle binary and comparison operators that can appear in
959 tree op0 = TREE_OPERAND (rhs, 0);
960 tree op1 = TREE_OPERAND (rhs, 1);
962 /* Simplify the operands down to constants when appropriate. */
963 if (TREE_CODE (op0) == SSA_NAME)
965 prop_value_t *val = get_value (op0);
966 if (val->lattice_val == CONSTANT)
970 if (TREE_CODE (op1) == SSA_NAME)
972 prop_value_t *val = get_value (op1);
973 if (val->lattice_val == CONSTANT)
977 return fold_binary (code, TREE_TYPE (rhs), op0, op1);
980 /* We may be able to fold away calls to builtin functions if their
981 arguments are constants. */
982 else if (code == CALL_EXPR
983 && TREE_CODE (CALL_EXPR_FN (rhs)) == ADDR_EXPR
984 && TREE_CODE (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)) == FUNCTION_DECL
985 && DECL_BUILT_IN (TREE_OPERAND (CALL_EXPR_FN (rhs), 0)))
987 if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_USE))
994 /* Preserve the original values of every operand. */
995 orig = XNEWVEC (tree, NUM_SSA_OPERANDS (stmt, SSA_OP_USE));
996 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE)
999 /* Substitute operands with their values and try to fold. */
1000 replace_uses_in (stmt, NULL, const_val);
1001 retval = fold_call_expr (rhs, false);
1003 /* Restore operands to their original form. */
1005 FOR_EACH_SSA_USE_OPERAND (var_p, stmt, iter, SSA_OP_USE)
1006 SET_USE (var_p, orig[i++]);
1013 /* If we got a simplified form, see if we need to convert its type. */
1015 return fold_convert (TREE_TYPE (rhs), retval);
1017 /* No simplification was possible. */
1022 /* Return the tree representing the element referenced by T if T is an
1023 ARRAY_REF or COMPONENT_REF into constant aggregates. Return
1024 NULL_TREE otherwise. */
1027 fold_const_aggregate_ref (tree t)
1029 prop_value_t *value;
1030 tree base, ctor, idx, field;
1031 unsigned HOST_WIDE_INT cnt;
1034 switch (TREE_CODE (t))
1037 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1038 DECL_INITIAL. If BASE is a nested reference into another
1039 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1040 the inner reference. */
1041 base = TREE_OPERAND (t, 0);
1042 switch (TREE_CODE (base))
1045 if (!TREE_READONLY (base)
1046 || TREE_CODE (TREE_TYPE (base)) != ARRAY_TYPE
1047 || !targetm.binds_local_p (base))
1050 ctor = DECL_INITIAL (base);
1055 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);
1166 /* Evaluate statement STMT. */
1169 evaluate_stmt (tree stmt)
1172 tree simplified = NULL_TREE;
1173 ccp_lattice_t likelyvalue = likely_value (stmt);
1176 val.mem_ref = NULL_TREE;
1178 fold_defer_overflow_warnings ();
1180 /* If the statement is likely to have a CONSTANT result, then try
1181 to fold the statement to determine the constant value. */
1182 if (likelyvalue == CONSTANT)
1183 simplified = ccp_fold (stmt);
1184 /* If the statement is likely to have a VARYING result, then do not
1185 bother folding the statement. */
1186 if (likelyvalue == VARYING)
1187 simplified = get_rhs (stmt);
1188 /* If the statement is an ARRAY_REF or COMPONENT_REF into constant
1189 aggregates, extract the referenced constant. Otherwise the
1190 statement is likely to have an UNDEFINED value, and there will be
1191 nothing to do. Note that fold_const_aggregate_ref returns
1192 NULL_TREE if the first case does not match. */
1193 else if (!simplified)
1194 simplified = fold_const_aggregate_ref (get_rhs (stmt));
1196 is_constant = simplified && is_gimple_min_invariant (simplified);
1198 fold_undefer_overflow_warnings (is_constant, stmt, 0);
1202 /* The statement produced a constant value. */
1203 val.lattice_val = CONSTANT;
1204 val.value = simplified;
1208 /* The statement produced a nonconstant value. If the statement
1209 had UNDEFINED operands, then the result of the statement
1210 should be UNDEFINED. Otherwise, the statement is VARYING. */
1211 if (likelyvalue == UNDEFINED)
1212 val.lattice_val = likelyvalue;
1214 val.lattice_val = VARYING;
1216 val.value = NULL_TREE;
1223 /* Visit the assignment statement STMT. Set the value of its LHS to the
1224 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
1225 creates virtual definitions, set the value of each new name to that
1226 of the RHS (if we can derive a constant out of the RHS). */
1228 static enum ssa_prop_result
1229 visit_assignment (tree stmt, tree *output_p)
1233 enum ssa_prop_result retval;
1235 lhs = GIMPLE_STMT_OPERAND (stmt, 0);
1236 rhs = GIMPLE_STMT_OPERAND (stmt, 1);
1238 if (TREE_CODE (rhs) == SSA_NAME)
1240 /* For a simple copy operation, we copy the lattice values. */
1241 prop_value_t *nval = get_value (rhs);
1244 else if (do_store_ccp && stmt_makes_single_load (stmt))
1246 /* Same as above, but the RHS is not a gimple register and yet
1247 has a known VUSE. If STMT is loading from the same memory
1248 location that created the SSA_NAMEs for the virtual operands,
1249 we can propagate the value on the RHS. */
1250 prop_value_t *nval = get_value_loaded_by (stmt, const_val);
1254 && operand_equal_p (nval->mem_ref, rhs, 0))
1257 val = evaluate_stmt (stmt);
1260 /* Evaluate the statement. */
1261 val = evaluate_stmt (stmt);
1263 /* If the original LHS was a VIEW_CONVERT_EXPR, modify the constant
1264 value to be a VIEW_CONVERT_EXPR of the old constant value.
1266 ??? Also, if this was a definition of a bitfield, we need to widen
1267 the constant value into the type of the destination variable. This
1268 should not be necessary if GCC represented bitfields properly. */
1270 tree orig_lhs = GIMPLE_STMT_OPERAND (stmt, 0);
1272 if (TREE_CODE (orig_lhs) == VIEW_CONVERT_EXPR
1273 && val.lattice_val == CONSTANT)
1275 tree w = fold_unary (VIEW_CONVERT_EXPR,
1276 TREE_TYPE (TREE_OPERAND (orig_lhs, 0)),
1279 orig_lhs = TREE_OPERAND (orig_lhs, 0);
1280 if (w && is_gimple_min_invariant (w))
1284 val.lattice_val = VARYING;
1289 if (val.lattice_val == CONSTANT
1290 && TREE_CODE (orig_lhs) == COMPONENT_REF
1291 && DECL_BIT_FIELD (TREE_OPERAND (orig_lhs, 1)))
1293 tree w = widen_bitfield (val.value, TREE_OPERAND (orig_lhs, 1),
1296 if (w && is_gimple_min_invariant (w))
1300 val.lattice_val = VARYING;
1301 val.value = NULL_TREE;
1302 val.mem_ref = NULL_TREE;
1307 retval = SSA_PROP_NOT_INTERESTING;
1309 /* Set the lattice value of the statement's output. */
1310 if (TREE_CODE (lhs) == SSA_NAME)
1312 /* If STMT is an assignment to an SSA_NAME, we only have one
1314 if (set_lattice_value (lhs, val))
1317 if (val.lattice_val == VARYING)
1318 retval = SSA_PROP_VARYING;
1320 retval = SSA_PROP_INTERESTING;
1323 else if (do_store_ccp && stmt_makes_single_store (stmt))
1325 /* Otherwise, set the names in VDEF operands to the new
1326 constant value and mark the LHS as the memory reference
1327 associated with VAL. */
1332 /* Mark VAL as stored in the LHS of this assignment. */
1333 if (val.lattice_val == CONSTANT)
1336 /* Set the value of every VDEF to VAL. */
1338 FOR_EACH_SSA_TREE_OPERAND (vdef, stmt, i, SSA_OP_VIRTUAL_DEFS)
1340 /* See PR 29801. We may have VDEFs for read-only variables
1341 (see the handling of unmodifiable variables in
1342 add_virtual_operand); do not attempt to change their value. */
1343 if (get_symbol_constant_value (SSA_NAME_VAR (vdef)) != NULL_TREE)
1346 changed |= set_lattice_value (vdef, val);
1349 /* Note that for propagation purposes, we are only interested in
1350 visiting statements that load the exact same memory reference
1351 stored here. Those statements will have the exact same list
1352 of virtual uses, so it is enough to set the output of this
1353 statement to be its first virtual definition. */
1354 *output_p = first_vdef (stmt);
1357 if (val.lattice_val == VARYING)
1358 retval = SSA_PROP_VARYING;
1360 retval = SSA_PROP_INTERESTING;
1368 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
1369 if it can determine which edge will be taken. Otherwise, return
1370 SSA_PROP_VARYING. */
1372 static enum ssa_prop_result
1373 visit_cond_stmt (tree stmt, edge *taken_edge_p)
1378 block = bb_for_stmt (stmt);
1379 val = evaluate_stmt (stmt);
1381 /* Find which edge out of the conditional block will be taken and add it
1382 to the worklist. If no single edge can be determined statically,
1383 return SSA_PROP_VARYING to feed all the outgoing edges to the
1384 propagation engine. */
1385 *taken_edge_p = val.value ? find_taken_edge (block, val.value) : 0;
1387 return SSA_PROP_INTERESTING;
1389 return SSA_PROP_VARYING;
1393 /* Evaluate statement STMT. If the statement produces an output value and
1394 its evaluation changes the lattice value of its output, return
1395 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
1398 If STMT is a conditional branch and we can determine its truth
1399 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
1400 value, return SSA_PROP_VARYING. */
1402 static enum ssa_prop_result
1403 ccp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
1408 if (dump_file && (dump_flags & TDF_DETAILS))
1410 fprintf (dump_file, "\nVisiting statement:\n");
1411 print_generic_stmt (dump_file, stmt, dump_flags);
1412 fprintf (dump_file, "\n");
1415 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
1417 /* If the statement is an assignment that produces a single
1418 output value, evaluate its RHS to see if the lattice value of
1419 its output has changed. */
1420 return visit_assignment (stmt, output_p);
1422 else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR)
1424 /* If STMT is a conditional branch, see if we can determine
1425 which branch will be taken. */
1426 return visit_cond_stmt (stmt, taken_edge_p);
1429 /* Any other kind of statement is not interesting for constant
1430 propagation and, therefore, not worth simulating. */
1431 if (dump_file && (dump_flags & TDF_DETAILS))
1432 fprintf (dump_file, "No interesting values produced. Marked VARYING.\n");
1434 /* Definitions made by statements other than assignments to
1435 SSA_NAMEs represent unknown modifications to their outputs.
1436 Mark them VARYING. */
1437 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
1439 prop_value_t v = { VARYING, NULL_TREE, NULL_TREE };
1440 set_lattice_value (def, v);
1443 return SSA_PROP_VARYING;
1447 /* Main entry point for SSA Conditional Constant Propagation. */
1450 execute_ssa_ccp (bool store_ccp)
1452 do_store_ccp = store_ccp;
1454 ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node);
1455 if (ccp_finalize ())
1456 return (TODO_cleanup_cfg | TODO_update_ssa | TODO_remove_unused_locals);
1465 return execute_ssa_ccp (false);
1472 return flag_tree_ccp != 0;
1476 struct tree_opt_pass pass_ccp =
1479 gate_ccp, /* gate */
1480 do_ssa_ccp, /* execute */
1483 0, /* static_pass_number */
1484 TV_TREE_CCP, /* tv_id */
1485 PROP_cfg | PROP_ssa, /* 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 */
1496 do_ssa_store_ccp (void)
1498 /* If STORE-CCP is not enabled, we just run regular CCP. */
1499 return execute_ssa_ccp (flag_tree_store_ccp != 0);
1503 gate_store_ccp (void)
1505 /* STORE-CCP is enabled only with -ftree-store-ccp, but when
1506 -fno-tree-store-ccp is specified, we should run regular CCP.
1507 That's why the pass is enabled with either flag. */
1508 return flag_tree_store_ccp != 0 || flag_tree_ccp != 0;
1512 struct tree_opt_pass pass_store_ccp =
1514 "store_ccp", /* name */
1515 gate_store_ccp, /* gate */
1516 do_ssa_store_ccp, /* execute */
1519 0, /* static_pass_number */
1520 TV_TREE_STORE_CCP, /* tv_id */
1521 PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
1522 0, /* properties_provided */
1523 0, /* properties_destroyed */
1524 0, /* todo_flags_start */
1525 TODO_dump_func | TODO_verify_ssa
1526 | TODO_verify_stmts | TODO_ggc_collect,/* todo_flags_finish */
1530 /* Given a constant value VAL for bitfield FIELD, and a destination
1531 variable VAR, return VAL appropriately widened to fit into VAR. If
1532 FIELD is wider than HOST_WIDE_INT, NULL is returned. */
1535 widen_bitfield (tree val, tree field, tree var)
1537 unsigned HOST_WIDE_INT var_size, field_size;
1539 unsigned HOST_WIDE_INT mask;
1542 /* We can only do this if the size of the type and field and VAL are
1543 all constants representable in HOST_WIDE_INT. */
1544 if (!host_integerp (TYPE_SIZE (TREE_TYPE (var)), 1)
1545 || !host_integerp (DECL_SIZE (field), 1)
1546 || !host_integerp (val, 0))
1549 var_size = tree_low_cst (TYPE_SIZE (TREE_TYPE (var)), 1);
1550 field_size = tree_low_cst (DECL_SIZE (field), 1);
1552 /* Give up if either the bitfield or the variable are too wide. */
1553 if (field_size > HOST_BITS_PER_WIDE_INT || var_size > HOST_BITS_PER_WIDE_INT)
1556 gcc_assert (var_size >= field_size);
1558 /* If the sign bit of the value is not set or the field's type is unsigned,
1559 just mask off the high order bits of the value. */
1560 if (DECL_UNSIGNED (field)
1561 || !(tree_low_cst (val, 0) & (((HOST_WIDE_INT)1) << (field_size - 1))))
1563 /* Zero extension. Build a mask with the lower 'field_size' bits
1564 set and a BIT_AND_EXPR node to clear the high order bits of
1566 for (i = 0, mask = 0; i < field_size; i++)
1567 mask |= ((HOST_WIDE_INT) 1) << i;
1569 wide_val = fold_build2 (BIT_AND_EXPR, TREE_TYPE (var), val,
1570 build_int_cst (TREE_TYPE (var), mask));
1574 /* Sign extension. Create a mask with the upper 'field_size'
1575 bits set and a BIT_IOR_EXPR to set the high order bits of the
1577 for (i = 0, mask = 0; i < (var_size - field_size); i++)
1578 mask |= ((HOST_WIDE_INT) 1) << (var_size - i - 1);
1580 wide_val = fold_build2 (BIT_IOR_EXPR, TREE_TYPE (var), val,
1581 build_int_cst (TREE_TYPE (var), mask));
1588 /* A subroutine of fold_stmt_r. Attempts to fold *(A+O) to A[X].
1589 BASE is an array type. OFFSET is a byte displacement. ORIG_TYPE
1590 is the desired result type. */
1593 maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type)
1595 tree min_idx, idx, idx_type, elt_offset = integer_zero_node;
1596 tree array_type, elt_type, elt_size;
1599 /* If BASE is an ARRAY_REF, we can pick up another offset (this time
1600 measured in units of the size of elements type) from that ARRAY_REF).
1601 We can't do anything if either is variable.
1603 The case we handle here is *(&A[N]+O). */
1604 if (TREE_CODE (base) == ARRAY_REF)
1606 tree low_bound = array_ref_low_bound (base);
1608 elt_offset = TREE_OPERAND (base, 1);
1609 if (TREE_CODE (low_bound) != INTEGER_CST
1610 || TREE_CODE (elt_offset) != INTEGER_CST)
1613 elt_offset = int_const_binop (MINUS_EXPR, elt_offset, low_bound, 0);
1614 base = TREE_OPERAND (base, 0);
1617 /* Ignore stupid user tricks of indexing non-array variables. */
1618 array_type = TREE_TYPE (base);
1619 if (TREE_CODE (array_type) != ARRAY_TYPE)
1621 elt_type = TREE_TYPE (array_type);
1622 if (!useless_type_conversion_p (orig_type, elt_type))
1625 /* Use signed size type for intermediate computation on the index. */
1626 idx_type = signed_type_for (size_type_node);
1628 /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the
1629 element type (so we can use the alignment if it's not constant).
1630 Otherwise, compute the offset as an index by using a division. If the
1631 division isn't exact, then don't do anything. */
1632 elt_size = TYPE_SIZE_UNIT (elt_type);
1635 if (integer_zerop (offset))
1637 if (TREE_CODE (elt_size) != INTEGER_CST)
1638 elt_size = size_int (TYPE_ALIGN (elt_type));
1640 idx = build_int_cst (idx_type, 0);
1644 unsigned HOST_WIDE_INT lquo, lrem;
1645 HOST_WIDE_INT hquo, hrem;
1648 /* The final array offset should be signed, so we need
1649 to sign-extend the (possibly pointer) offset here
1650 and use signed division. */
1651 soffset = double_int_sext (tree_to_double_int (offset),
1652 TYPE_PRECISION (TREE_TYPE (offset)));
1653 if (TREE_CODE (elt_size) != INTEGER_CST
1654 || div_and_round_double (TRUNC_DIV_EXPR, 0,
1655 soffset.low, soffset.high,
1656 TREE_INT_CST_LOW (elt_size),
1657 TREE_INT_CST_HIGH (elt_size),
1658 &lquo, &hquo, &lrem, &hrem)
1662 idx = build_int_cst_wide (idx_type, lquo, hquo);
1665 /* Assume the low bound is zero. If there is a domain type, get the
1666 low bound, if any, convert the index into that type, and add the
1668 min_idx = build_int_cst (idx_type, 0);
1669 domain_type = TYPE_DOMAIN (array_type);
1672 idx_type = domain_type;
1673 if (TYPE_MIN_VALUE (idx_type))
1674 min_idx = TYPE_MIN_VALUE (idx_type);
1676 min_idx = fold_convert (idx_type, min_idx);
1678 if (TREE_CODE (min_idx) != INTEGER_CST)
1681 elt_offset = fold_convert (idx_type, elt_offset);
1684 if (!integer_zerop (min_idx))
1685 idx = int_const_binop (PLUS_EXPR, idx, min_idx, 0);
1686 if (!integer_zerop (elt_offset))
1687 idx = int_const_binop (PLUS_EXPR, idx, elt_offset, 0);
1689 /* Make sure to possibly truncate late after offsetting. */
1690 idx = fold_convert (idx_type, idx);
1692 /* We don't want to construct access past array bounds. For example
1695 c[3][2]; should not be simplified into (*c)[14] or tree-vrp will give false
1697 if (domain_type && TYPE_MAX_VALUE (domain_type)
1698 && TREE_CODE (TYPE_MAX_VALUE (domain_type)) == INTEGER_CST)
1700 tree up_bound = TYPE_MAX_VALUE (domain_type);
1702 if (tree_int_cst_lt (up_bound, idx)
1703 /* Accesses after the end of arrays of size 0 (gcc
1704 extension) and 1 are likely intentional ("struct
1706 && compare_tree_int (up_bound, 1) > 0)
1710 return build4 (ARRAY_REF, elt_type, base, idx, NULL_TREE, NULL_TREE);
1714 /* Attempt to fold *(S+O) to S.X.
1715 BASE is a record type. OFFSET is a byte displacement. ORIG_TYPE
1716 is the desired result type. */
1719 maybe_fold_offset_to_component_ref (tree record_type, tree base, tree offset,
1720 tree orig_type, bool base_is_ptr)
1722 tree f, t, field_type, tail_array_field, field_offset;
1726 if (TREE_CODE (record_type) != RECORD_TYPE
1727 && TREE_CODE (record_type) != UNION_TYPE
1728 && TREE_CODE (record_type) != QUAL_UNION_TYPE)
1731 /* Short-circuit silly cases. */
1732 if (useless_type_conversion_p (record_type, orig_type))
1735 tail_array_field = NULL_TREE;
1736 for (f = TYPE_FIELDS (record_type); f ; f = TREE_CHAIN (f))
1740 if (TREE_CODE (f) != FIELD_DECL)
1742 if (DECL_BIT_FIELD (f))
1745 if (!DECL_FIELD_OFFSET (f))
1747 field_offset = byte_position (f);
1748 if (TREE_CODE (field_offset) != INTEGER_CST)
1751 /* ??? Java creates "interesting" fields for representing base classes.
1752 They have no name, and have no context. With no context, we get into
1753 trouble with nonoverlapping_component_refs_p. Skip them. */
1754 if (!DECL_FIELD_CONTEXT (f))
1757 /* The previous array field isn't at the end. */
1758 tail_array_field = NULL_TREE;
1760 /* Check to see if this offset overlaps with the field. */
1761 cmp = tree_int_cst_compare (field_offset, offset);
1765 field_type = TREE_TYPE (f);
1767 /* Here we exactly match the offset being checked. If the types match,
1768 then we can return that field. */
1770 && useless_type_conversion_p (orig_type, field_type))
1773 base = build1 (INDIRECT_REF, record_type, base);
1774 t = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE);
1778 /* Don't care about offsets into the middle of scalars. */
1779 if (!AGGREGATE_TYPE_P (field_type))
1782 /* Check for array at the end of the struct. This is often
1783 used as for flexible array members. We should be able to
1784 turn this into an array access anyway. */
1785 if (TREE_CODE (field_type) == ARRAY_TYPE)
1786 tail_array_field = f;
1788 /* Check the end of the field against the offset. */
1789 if (!DECL_SIZE_UNIT (f)
1790 || TREE_CODE (DECL_SIZE_UNIT (f)) != INTEGER_CST)
1792 t = int_const_binop (MINUS_EXPR, offset, field_offset, 1);
1793 if (!tree_int_cst_lt (t, DECL_SIZE_UNIT (f)))
1796 /* If we matched, then set offset to the displacement into
1799 new_base = build1 (INDIRECT_REF, record_type, base);
1802 new_base = build3 (COMPONENT_REF, field_type, new_base, f, NULL_TREE);
1804 /* Recurse to possibly find the match. */
1805 ret = maybe_fold_offset_to_array_ref (new_base, t, orig_type);
1808 ret = maybe_fold_offset_to_component_ref (field_type, new_base, t,
1814 if (!tail_array_field)
1817 f = tail_array_field;
1818 field_type = TREE_TYPE (f);
1819 offset = int_const_binop (MINUS_EXPR, offset, byte_position (f), 1);
1821 /* If we get here, we've got an aggregate field, and a possibly
1822 nonzero offset into them. Recurse and hope for a valid match. */
1824 base = build1 (INDIRECT_REF, record_type, base);
1825 base = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE);
1827 t = maybe_fold_offset_to_array_ref (base, offset, orig_type);
1830 return maybe_fold_offset_to_component_ref (field_type, base, offset,
1834 /* Attempt to express (ORIG_TYPE)BASE+OFFSET as BASE->field_of_orig_type
1835 or BASE[index] or by combination of those.
1837 Before attempting the conversion strip off existing ADDR_EXPRs and
1838 handled component refs. */
1841 maybe_fold_offset_to_reference (tree base, tree offset, tree orig_type)
1845 bool base_is_ptr = true;
1848 if (TREE_CODE (base) == ADDR_EXPR)
1850 base_is_ptr = false;
1852 base = TREE_OPERAND (base, 0);
1854 /* Handle case where existing COMPONENT_REF pick e.g. wrong field of union,
1855 so it needs to be removed and new COMPONENT_REF constructed.
1856 The wrong COMPONENT_REF are often constructed by folding the
1857 (type *)&object within the expression (type *)&object+offset */
1858 if (handled_component_p (base) && 0)
1860 HOST_WIDE_INT sub_offset, size, maxsize;
1862 newbase = get_ref_base_and_extent (base, &sub_offset,
1864 gcc_assert (newbase);
1865 gcc_assert (!(sub_offset & (BITS_PER_UNIT - 1)));
1866 if (size == maxsize)
1870 offset = int_const_binop (PLUS_EXPR, offset,
1871 build_int_cst (TREE_TYPE (offset),
1872 sub_offset / BITS_PER_UNIT), 1);
1875 if (useless_type_conversion_p (orig_type, TREE_TYPE (base))
1876 && integer_zerop (offset))
1878 type = TREE_TYPE (base);
1883 if (!POINTER_TYPE_P (TREE_TYPE (base)))
1885 type = TREE_TYPE (TREE_TYPE (base));
1887 ret = maybe_fold_offset_to_component_ref (type, base, offset,
1888 orig_type, base_is_ptr);
1892 base = build1 (INDIRECT_REF, type, base);
1893 ret = maybe_fold_offset_to_array_ref (base, offset, orig_type);
1898 /* A subroutine of fold_stmt_r. Attempt to simplify *(BASE+OFFSET).
1899 Return the simplified expression, or NULL if nothing could be done. */
1902 maybe_fold_stmt_indirect (tree expr, tree base, tree offset)
1905 bool volatile_p = TREE_THIS_VOLATILE (expr);
1907 /* We may well have constructed a double-nested PLUS_EXPR via multiple
1908 substitutions. Fold that down to one. Remove NON_LVALUE_EXPRs that
1909 are sometimes added. */
1911 STRIP_TYPE_NOPS (base);
1912 TREE_OPERAND (expr, 0) = base;
1914 /* One possibility is that the address reduces to a string constant. */
1915 t = fold_read_from_constant_string (expr);
1919 /* Add in any offset from a POINTER_PLUS_EXPR. */
1920 if (TREE_CODE (base) == POINTER_PLUS_EXPR)
1924 offset2 = TREE_OPERAND (base, 1);
1925 if (TREE_CODE (offset2) != INTEGER_CST)
1927 base = TREE_OPERAND (base, 0);
1929 offset = fold_convert (sizetype,
1930 int_const_binop (PLUS_EXPR, offset, offset2, 1));
1933 if (TREE_CODE (base) == ADDR_EXPR)
1935 tree base_addr = base;
1937 /* Strip the ADDR_EXPR. */
1938 base = TREE_OPERAND (base, 0);
1940 /* Fold away CONST_DECL to its value, if the type is scalar. */
1941 if (TREE_CODE (base) == CONST_DECL
1942 && ccp_decl_initial_min_invariant (DECL_INITIAL (base)))
1943 return DECL_INITIAL (base);
1945 /* Try folding *(&B+O) to B.X. */
1946 t = maybe_fold_offset_to_reference (base_addr, offset,
1950 TREE_THIS_VOLATILE (t) = volatile_p;
1956 /* We can get here for out-of-range string constant accesses,
1957 such as "_"[3]. Bail out of the entire substitution search
1958 and arrange for the entire statement to be replaced by a
1959 call to __builtin_trap. In all likelihood this will all be
1960 constant-folded away, but in the meantime we can't leave with
1961 something that get_expr_operands can't understand. */
1965 if (TREE_CODE (t) == ADDR_EXPR
1966 && TREE_CODE (TREE_OPERAND (t, 0)) == STRING_CST)
1968 /* FIXME: Except that this causes problems elsewhere with dead
1969 code not being deleted, and we die in the rtl expanders
1970 because we failed to remove some ssa_name. In the meantime,
1971 just return zero. */
1972 /* FIXME2: This condition should be signaled by
1973 fold_read_from_constant_string directly, rather than
1974 re-checking for it here. */
1975 return integer_zero_node;
1978 /* Try folding *(B+O) to B->X. Still an improvement. */
1979 if (POINTER_TYPE_P (TREE_TYPE (base)))
1981 t = maybe_fold_offset_to_reference (base, offset,
1988 /* Otherwise we had an offset that we could not simplify. */
1993 /* A subroutine of fold_stmt_r. EXPR is a POINTER_PLUS_EXPR.
1995 A quaint feature extant in our address arithmetic is that there
1996 can be hidden type changes here. The type of the result need
1997 not be the same as the type of the input pointer.
1999 What we're after here is an expression of the form
2000 (T *)(&array + const)
2001 where the cast doesn't actually exist, but is implicit in the
2002 type of the POINTER_PLUS_EXPR. We'd like to turn this into
2004 which may be able to propagate further. */
2007 maybe_fold_stmt_addition (tree expr)
2009 tree op0 = TREE_OPERAND (expr, 0);
2010 tree op1 = TREE_OPERAND (expr, 1);
2011 tree ptr_type = TREE_TYPE (expr);
2015 gcc_assert (TREE_CODE (expr) == POINTER_PLUS_EXPR);
2017 /* It had better be a constant. */
2018 if (TREE_CODE (op1) != INTEGER_CST)
2020 /* The first operand should be an ADDR_EXPR. */
2021 if (TREE_CODE (op0) != ADDR_EXPR)
2023 op0 = TREE_OPERAND (op0, 0);
2025 /* If the first operand is an ARRAY_REF, expand it so that we can fold
2026 the offset into it. */
2027 while (TREE_CODE (op0) == ARRAY_REF)
2029 tree array_obj = TREE_OPERAND (op0, 0);
2030 tree array_idx = TREE_OPERAND (op0, 1);
2031 tree elt_type = TREE_TYPE (op0);
2032 tree elt_size = TYPE_SIZE_UNIT (elt_type);
2035 if (TREE_CODE (array_idx) != INTEGER_CST)
2037 if (TREE_CODE (elt_size) != INTEGER_CST)
2040 /* Un-bias the index by the min index of the array type. */
2041 min_idx = TYPE_DOMAIN (TREE_TYPE (array_obj));
2044 min_idx = TYPE_MIN_VALUE (min_idx);
2047 if (TREE_CODE (min_idx) != INTEGER_CST)
2050 array_idx = fold_convert (TREE_TYPE (min_idx), array_idx);
2051 if (!integer_zerop (min_idx))
2052 array_idx = int_const_binop (MINUS_EXPR, array_idx,
2057 /* Convert the index to a byte offset. */
2058 array_idx = fold_convert (sizetype, array_idx);
2059 array_idx = int_const_binop (MULT_EXPR, array_idx, elt_size, 0);
2061 /* Update the operands for the next round, or for folding. */
2062 op1 = int_const_binop (PLUS_EXPR,
2067 ptd_type = TREE_TYPE (ptr_type);
2069 /* At which point we can try some of the same things as for indirects. */
2070 t = maybe_fold_offset_to_array_ref (op0, op1, ptd_type);
2072 t = maybe_fold_offset_to_component_ref (TREE_TYPE (op0), op0, op1,
2075 t = build1 (ADDR_EXPR, ptr_type, t);
2080 /* For passing state through walk_tree into fold_stmt_r and its
2083 struct fold_stmt_r_data
2087 bool *inside_addr_expr_p;
2090 /* Subroutine of fold_stmt called via walk_tree. We perform several
2091 simplifications of EXPR_P, mostly having to do with pointer arithmetic. */
2094 fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data)
2096 struct fold_stmt_r_data *fold_stmt_r_data = (struct fold_stmt_r_data *) data;
2097 bool *inside_addr_expr_p = fold_stmt_r_data->inside_addr_expr_p;
2098 bool *changed_p = fold_stmt_r_data->changed_p;
2099 tree expr = *expr_p, t;
2100 bool volatile_p = TREE_THIS_VOLATILE (expr);
2102 /* ??? It'd be nice if walk_tree had a pre-order option. */
2103 switch (TREE_CODE (expr))
2106 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2111 t = maybe_fold_stmt_indirect (expr, TREE_OPERAND (expr, 0),
2116 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2121 if (POINTER_TYPE_P (TREE_TYPE (expr))
2122 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0)))
2123 && (t = maybe_fold_offset_to_reference
2124 (TREE_OPERAND (expr, 0),
2126 TREE_TYPE (TREE_TYPE (expr)))))
2128 tree ptr_type = build_pointer_type (TREE_TYPE (t));
2129 if (!useless_type_conversion_p (TREE_TYPE (expr), ptr_type))
2131 t = build_fold_addr_expr_with_type (t, ptr_type);
2135 /* ??? Could handle more ARRAY_REFs here, as a variant of INDIRECT_REF.
2136 We'd only want to bother decomposing an existing ARRAY_REF if
2137 the base array is found to have another offset contained within.
2138 Otherwise we'd be wasting time. */
2140 /* If we are not processing expressions found within an
2141 ADDR_EXPR, then we can fold constant array references. */
2142 if (!*inside_addr_expr_p)
2143 t = fold_read_from_constant_string (expr);
2149 *inside_addr_expr_p = true;
2150 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2151 *inside_addr_expr_p = false;
2156 /* Set TREE_INVARIANT properly so that the value is properly
2157 considered constant, and so gets propagated as expected. */
2159 recompute_tree_invariant_for_addr_expr (expr);
2162 case POINTER_PLUS_EXPR:
2163 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2166 t = walk_tree (&TREE_OPERAND (expr, 1), fold_stmt_r, data, NULL);
2171 t = maybe_fold_stmt_addition (expr);
2175 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2180 /* Make sure the FIELD_DECL is actually a field in the type on the lhs.
2181 We've already checked that the records are compatible, so we should
2182 come up with a set of compatible fields. */
2184 tree expr_record = TREE_TYPE (TREE_OPERAND (expr, 0));
2185 tree expr_field = TREE_OPERAND (expr, 1);
2187 if (DECL_FIELD_CONTEXT (expr_field) != TYPE_MAIN_VARIANT (expr_record))
2189 expr_field = find_compatible_field (expr_record, expr_field);
2190 TREE_OPERAND (expr, 1) = expr_field;
2195 case TARGET_MEM_REF:
2196 t = maybe_fold_tmr (expr);
2200 if (COMPARISON_CLASS_P (TREE_OPERAND (expr, 0)))
2202 tree op0 = TREE_OPERAND (expr, 0);
2206 fold_defer_overflow_warnings ();
2207 tem = fold_binary (TREE_CODE (op0), TREE_TYPE (op0),
2208 TREE_OPERAND (op0, 0),
2209 TREE_OPERAND (op0, 1));
2210 set = tem && set_rhs (expr_p, tem);
2211 fold_undefer_overflow_warnings (set, fold_stmt_r_data->stmt, 0);
2226 /* Preserve volatileness of the original expression. */
2227 TREE_THIS_VOLATILE (t) = volatile_p;
2236 /* Return the string length, maximum string length or maximum value of
2238 If ARG is an SSA name variable, follow its use-def chains. If LENGTH
2239 is not NULL and, for TYPE == 0, its value is not equal to the length
2240 we determine or if we are unable to determine the length or value,
2241 return false. VISITED is a bitmap of visited variables.
2242 TYPE is 0 if string length should be returned, 1 for maximum string
2243 length and 2 for maximum value ARG can have. */
2246 get_maxval_strlen (tree arg, tree *length, bitmap visited, int type)
2248 tree var, def_stmt, val;
2250 if (TREE_CODE (arg) != SSA_NAME)
2252 if (TREE_CODE (arg) == COND_EXPR)
2253 return get_maxval_strlen (COND_EXPR_THEN (arg), length, visited, type)
2254 && get_maxval_strlen (COND_EXPR_ELSE (arg), length, visited, type);
2259 if (TREE_CODE (val) != INTEGER_CST
2260 || tree_int_cst_sgn (val) < 0)
2264 val = c_strlen (arg, 1);
2272 if (TREE_CODE (*length) != INTEGER_CST
2273 || TREE_CODE (val) != INTEGER_CST)
2276 if (tree_int_cst_lt (*length, val))
2280 else if (simple_cst_equal (val, *length) != 1)
2288 /* If we were already here, break the infinite cycle. */
2289 if (bitmap_bit_p (visited, SSA_NAME_VERSION (arg)))
2291 bitmap_set_bit (visited, SSA_NAME_VERSION (arg));
2294 def_stmt = SSA_NAME_DEF_STMT (var);
2296 switch (TREE_CODE (def_stmt))
2298 case GIMPLE_MODIFY_STMT:
2302 /* The RHS of the statement defining VAR must either have a
2303 constant length or come from another SSA_NAME with a constant
2305 rhs = GIMPLE_STMT_OPERAND (def_stmt, 1);
2307 return get_maxval_strlen (rhs, length, visited, type);
2312 /* All the arguments of the PHI node must have the same constant
2316 for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++)
2318 tree arg = PHI_ARG_DEF (def_stmt, i);
2320 /* If this PHI has itself as an argument, we cannot
2321 determine the string length of this argument. However,
2322 if we can find a constant string length for the other
2323 PHI args then we can still be sure that this is a
2324 constant string length. So be optimistic and just
2325 continue with the next argument. */
2326 if (arg == PHI_RESULT (def_stmt))
2329 if (!get_maxval_strlen (arg, length, visited, type))
2345 /* Fold builtin call FN in statement STMT. If it cannot be folded into a
2346 constant, return NULL_TREE. Otherwise, return its constant value. */
2349 ccp_fold_builtin (tree stmt, tree fn)
2351 tree result, val[3];
2353 int arg_mask, i, type;
2356 call_expr_arg_iterator iter;
2359 ignore = TREE_CODE (stmt) != GIMPLE_MODIFY_STMT;
2361 /* First try the generic builtin folder. If that succeeds, return the
2363 result = fold_call_expr (fn, ignore);
2367 STRIP_NOPS (result);
2371 /* Ignore MD builtins. */
2372 callee = get_callee_fndecl (fn);
2373 if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_MD)
2376 /* If the builtin could not be folded, and it has no argument list,
2378 nargs = call_expr_nargs (fn);
2382 /* Limit the work only for builtins we know how to simplify. */
2383 switch (DECL_FUNCTION_CODE (callee))
2385 case BUILT_IN_STRLEN:
2386 case BUILT_IN_FPUTS:
2387 case BUILT_IN_FPUTS_UNLOCKED:
2391 case BUILT_IN_STRCPY:
2392 case BUILT_IN_STRNCPY:
2396 case BUILT_IN_MEMCPY_CHK:
2397 case BUILT_IN_MEMPCPY_CHK:
2398 case BUILT_IN_MEMMOVE_CHK:
2399 case BUILT_IN_MEMSET_CHK:
2400 case BUILT_IN_STRNCPY_CHK:
2404 case BUILT_IN_STRCPY_CHK:
2405 case BUILT_IN_STPCPY_CHK:
2409 case BUILT_IN_SNPRINTF_CHK:
2410 case BUILT_IN_VSNPRINTF_CHK:
2418 /* Try to use the dataflow information gathered by the CCP process. */
2419 visited = BITMAP_ALLOC (NULL);
2421 memset (val, 0, sizeof (val));
2422 init_call_expr_arg_iterator (fn, &iter);
2423 for (i = 0; arg_mask; i++, arg_mask >>= 1)
2425 a = next_call_expr_arg (&iter);
2428 bitmap_clear (visited);
2429 if (!get_maxval_strlen (a, &val[i], visited, type))
2434 BITMAP_FREE (visited);
2437 switch (DECL_FUNCTION_CODE (callee))
2439 case BUILT_IN_STRLEN:
2442 tree new_val = fold_convert (TREE_TYPE (fn), val[0]);
2444 /* If the result is not a valid gimple value, or not a cast
2445 of a valid gimple value, then we can not use the result. */
2446 if (is_gimple_val (new_val)
2447 || (is_gimple_cast (new_val)
2448 && is_gimple_val (TREE_OPERAND (new_val, 0))))
2453 case BUILT_IN_STRCPY:
2454 if (val[1] && is_gimple_val (val[1]) && nargs == 2)
2455 result = fold_builtin_strcpy (callee,
2456 CALL_EXPR_ARG (fn, 0),
2457 CALL_EXPR_ARG (fn, 1),
2461 case BUILT_IN_STRNCPY:
2462 if (val[1] && is_gimple_val (val[1]) && nargs == 3)
2463 result = fold_builtin_strncpy (callee,
2464 CALL_EXPR_ARG (fn, 0),
2465 CALL_EXPR_ARG (fn, 1),
2466 CALL_EXPR_ARG (fn, 2),
2470 case BUILT_IN_FPUTS:
2471 result = fold_builtin_fputs (CALL_EXPR_ARG (fn, 0),
2472 CALL_EXPR_ARG (fn, 1),
2473 TREE_CODE (stmt) != GIMPLE_MODIFY_STMT, 0,
2477 case BUILT_IN_FPUTS_UNLOCKED:
2478 result = fold_builtin_fputs (CALL_EXPR_ARG (fn, 0),
2479 CALL_EXPR_ARG (fn, 1),
2480 TREE_CODE (stmt) != GIMPLE_MODIFY_STMT, 1,
2484 case BUILT_IN_MEMCPY_CHK:
2485 case BUILT_IN_MEMPCPY_CHK:
2486 case BUILT_IN_MEMMOVE_CHK:
2487 case BUILT_IN_MEMSET_CHK:
2488 if (val[2] && is_gimple_val (val[2]))
2489 result = fold_builtin_memory_chk (callee,
2490 CALL_EXPR_ARG (fn, 0),
2491 CALL_EXPR_ARG (fn, 1),
2492 CALL_EXPR_ARG (fn, 2),
2493 CALL_EXPR_ARG (fn, 3),
2495 DECL_FUNCTION_CODE (callee));
2498 case BUILT_IN_STRCPY_CHK:
2499 case BUILT_IN_STPCPY_CHK:
2500 if (val[1] && is_gimple_val (val[1]))
2501 result = fold_builtin_stxcpy_chk (callee,
2502 CALL_EXPR_ARG (fn, 0),
2503 CALL_EXPR_ARG (fn, 1),
2504 CALL_EXPR_ARG (fn, 2),
2506 DECL_FUNCTION_CODE (callee));
2509 case BUILT_IN_STRNCPY_CHK:
2510 if (val[2] && is_gimple_val (val[2]))
2511 result = fold_builtin_strncpy_chk (CALL_EXPR_ARG (fn, 0),
2512 CALL_EXPR_ARG (fn, 1),
2513 CALL_EXPR_ARG (fn, 2),
2514 CALL_EXPR_ARG (fn, 3),
2518 case BUILT_IN_SNPRINTF_CHK:
2519 case BUILT_IN_VSNPRINTF_CHK:
2520 if (val[1] && is_gimple_val (val[1]))
2521 result = fold_builtin_snprintf_chk (fn, val[1],
2522 DECL_FUNCTION_CODE (callee));
2529 if (result && ignore)
2530 result = fold_ignored_result (result);
2535 /* Fold the statement pointed to by STMT_P. In some cases, this function may
2536 replace the whole statement with a new one. Returns true iff folding
2537 makes any changes. */
2540 fold_stmt (tree *stmt_p)
2542 tree rhs, result, stmt;
2543 struct fold_stmt_r_data fold_stmt_r_data;
2544 bool changed = false;
2545 bool inside_addr_expr = false;
2549 fold_stmt_r_data.stmt = stmt;
2550 fold_stmt_r_data.changed_p = &changed;
2551 fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr;
2553 /* If we replaced constants and the statement makes pointer dereferences,
2554 then we may need to fold instances of *&VAR into VAR, etc. */
2555 if (walk_tree (stmt_p, fold_stmt_r, &fold_stmt_r_data, NULL))
2557 *stmt_p = build_call_expr (implicit_built_in_decls[BUILT_IN_TRAP], 0);
2561 rhs = get_rhs (stmt);
2566 if (TREE_CODE (rhs) == CALL_EXPR)
2570 /* Check for builtins that CCP can handle using information not
2571 available in the generic fold routines. */
2572 callee = get_callee_fndecl (rhs);
2573 if (callee && DECL_BUILT_IN (callee))
2574 result = ccp_fold_builtin (stmt, rhs);
2577 /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve
2578 here are when we've propagated the address of a decl into the
2580 /* ??? Should perhaps do this in fold proper. However, doing it
2581 there requires that we create a new CALL_EXPR, and that requires
2582 copying EH region info to the new node. Easier to just do it
2583 here where we can just smash the call operand. Also
2584 CALL_EXPR_RETURN_SLOT_OPT needs to be handled correctly and
2585 copied, fold_call_expr does not have not information. */
2586 callee = CALL_EXPR_FN (rhs);
2587 if (TREE_CODE (callee) == OBJ_TYPE_REF
2588 && lang_hooks.fold_obj_type_ref
2589 && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee)) == ADDR_EXPR
2590 && DECL_P (TREE_OPERAND
2591 (OBJ_TYPE_REF_OBJECT (callee), 0)))
2595 /* ??? Caution: Broken ADDR_EXPR semantics means that
2596 looking at the type of the operand of the addr_expr
2597 can yield an array type. See silly exception in
2598 check_pointer_types_r. */
2600 t = TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee)));
2601 t = lang_hooks.fold_obj_type_ref (callee, t);
2604 CALL_EXPR_FN (rhs) = t;
2610 else if (TREE_CODE (rhs) == COND_EXPR)
2612 tree temp = fold (COND_EXPR_COND (rhs));
2613 if (temp != COND_EXPR_COND (rhs))
2614 result = fold_build3 (COND_EXPR, TREE_TYPE (rhs), temp,
2615 COND_EXPR_THEN (rhs), COND_EXPR_ELSE (rhs));
2618 /* If we couldn't fold the RHS, hand over to the generic fold routines. */
2619 if (result == NULL_TREE)
2620 result = fold (rhs);
2622 /* Strip away useless type conversions. Both the NON_LVALUE_EXPR that
2623 may have been added by fold, and "useless" type conversions that might
2624 now be apparent due to propagation. */
2625 STRIP_USELESS_TYPE_CONVERSION (result);
2628 changed |= set_rhs (stmt_p, result);
2633 /* Perform the minimal folding on statement STMT. Only operations like
2634 *&x created by constant propagation are handled. The statement cannot
2635 be replaced with a new one. */
2638 fold_stmt_inplace (tree stmt)
2640 tree old_stmt = stmt, rhs, new_rhs;
2641 struct fold_stmt_r_data fold_stmt_r_data;
2642 bool changed = false;
2643 bool inside_addr_expr = false;
2645 fold_stmt_r_data.stmt = stmt;
2646 fold_stmt_r_data.changed_p = &changed;
2647 fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr;
2649 walk_tree (&stmt, fold_stmt_r, &fold_stmt_r_data, NULL);
2650 gcc_assert (stmt == old_stmt);
2652 rhs = get_rhs (stmt);
2653 if (!rhs || rhs == stmt)
2656 new_rhs = fold (rhs);
2657 STRIP_USELESS_TYPE_CONVERSION (new_rhs);
2661 changed |= set_rhs (&stmt, new_rhs);
2662 gcc_assert (stmt == old_stmt);
2667 /* Try to optimize out __builtin_stack_restore. Optimize it out
2668 if there is another __builtin_stack_restore in the same basic
2669 block and no calls or ASM_EXPRs are in between, or if this block's
2670 only outgoing edge is to EXIT_BLOCK and there are no calls or
2671 ASM_EXPRs after this __builtin_stack_restore. */
2674 optimize_stack_restore (basic_block bb, tree call, block_stmt_iterator i)
2676 tree stack_save, stmt, callee;
2678 if (TREE_CODE (call) != CALL_EXPR
2679 || call_expr_nargs (call) != 1
2680 || TREE_CODE (CALL_EXPR_ARG (call, 0)) != SSA_NAME
2681 || !POINTER_TYPE_P (TREE_TYPE (CALL_EXPR_ARG (call, 0))))
2684 for (bsi_next (&i); !bsi_end_p (i); bsi_next (&i))
2688 stmt = bsi_stmt (i);
2689 if (TREE_CODE (stmt) == ASM_EXPR)
2691 call = get_call_expr_in (stmt);
2695 callee = get_callee_fndecl (call);
2696 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
2699 if (DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_RESTORE)
2704 && (! single_succ_p (bb)
2705 || single_succ_edge (bb)->dest != EXIT_BLOCK_PTR))
2708 stack_save = SSA_NAME_DEF_STMT (CALL_EXPR_ARG (call, 0));
2709 if (TREE_CODE (stack_save) != GIMPLE_MODIFY_STMT
2710 || GIMPLE_STMT_OPERAND (stack_save, 0) != CALL_EXPR_ARG (call, 0)
2711 || TREE_CODE (GIMPLE_STMT_OPERAND (stack_save, 1)) != CALL_EXPR
2712 || tree_could_throw_p (stack_save)
2713 || !has_single_use (CALL_EXPR_ARG (call, 0)))
2716 callee = get_callee_fndecl (GIMPLE_STMT_OPERAND (stack_save, 1));
2718 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
2719 || DECL_FUNCTION_CODE (callee) != BUILT_IN_STACK_SAVE
2720 || call_expr_nargs (GIMPLE_STMT_OPERAND (stack_save, 1)) != 0)
2724 push_stmt_changes (&stmt);
2725 if (!set_rhs (&stmt,
2726 build_int_cst (TREE_TYPE (CALL_EXPR_ARG (call, 0)), 0)))
2728 discard_stmt_changes (&stmt);
2731 gcc_assert (stmt == stack_save);
2732 pop_stmt_changes (&stmt);
2734 return integer_zero_node;
2737 /* If va_list type is a simple pointer and nothing special is needed,
2738 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
2739 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
2740 pointer assignment. */
2743 optimize_stdarg_builtin (tree call)
2745 tree callee, lhs, rhs;
2746 bool va_list_simple_ptr;
2748 if (TREE_CODE (call) != CALL_EXPR)
2751 va_list_simple_ptr = POINTER_TYPE_P (va_list_type_node)
2752 && (TREE_TYPE (va_list_type_node) == void_type_node
2753 || TREE_TYPE (va_list_type_node) == char_type_node);
2755 callee = get_callee_fndecl (call);
2756 switch (DECL_FUNCTION_CODE (callee))
2758 case BUILT_IN_VA_START:
2759 if (!va_list_simple_ptr
2760 || targetm.expand_builtin_va_start != NULL
2761 || built_in_decls[BUILT_IN_NEXT_ARG] == NULL)
2764 if (call_expr_nargs (call) != 2)
2767 lhs = CALL_EXPR_ARG (call, 0);
2768 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
2769 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
2770 != TYPE_MAIN_VARIANT (va_list_type_node))
2773 lhs = build_fold_indirect_ref (lhs);
2774 rhs = build_call_expr (built_in_decls[BUILT_IN_NEXT_ARG],
2775 1, integer_zero_node);
2776 rhs = fold_convert (TREE_TYPE (lhs), rhs);
2777 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
2779 case BUILT_IN_VA_COPY:
2780 if (!va_list_simple_ptr)
2783 if (call_expr_nargs (call) != 2)
2786 lhs = CALL_EXPR_ARG (call, 0);
2787 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
2788 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
2789 != TYPE_MAIN_VARIANT (va_list_type_node))
2792 lhs = build_fold_indirect_ref (lhs);
2793 rhs = CALL_EXPR_ARG (call, 1);
2794 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs))
2795 != TYPE_MAIN_VARIANT (va_list_type_node))
2798 rhs = fold_convert (TREE_TYPE (lhs), rhs);
2799 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
2801 case BUILT_IN_VA_END:
2802 return integer_zero_node;
2809 /* Convert EXPR into a GIMPLE value suitable for substitution on the
2810 RHS of an assignment. Insert the necessary statements before
2812 When IGNORE is set, don't worry about the return value. */
2815 convert_to_gimple_builtin (block_stmt_iterator *si_p, tree expr, bool ignore)
2817 tree_stmt_iterator ti;
2818 tree stmt = bsi_stmt (*si_p);
2819 tree tmp, stmts = NULL;
2821 push_gimplify_context ();
2824 tmp = build_empty_stmt ();
2825 gimplify_and_add (expr, &stmts);
2828 tmp = get_initialized_tmp_var (expr, &stmts, NULL);
2829 pop_gimplify_context (NULL);
2831 if (EXPR_HAS_LOCATION (stmt))
2832 annotate_all_with_locus (&stmts, EXPR_LOCATION (stmt));
2834 /* The replacement can expose previously unreferenced variables. */
2835 for (ti = tsi_start (stmts); !tsi_end_p (ti); tsi_next (&ti))
2837 tree new_stmt = tsi_stmt (ti);
2838 find_new_referenced_vars (tsi_stmt_ptr (ti));
2839 bsi_insert_before (si_p, new_stmt, BSI_NEW_STMT);
2840 mark_symbols_for_renaming (new_stmt);
2848 /* A simple pass that attempts to fold all builtin functions. This pass
2849 is run after we've propagated as many constants as we can. */
2852 execute_fold_all_builtins (void)
2854 bool cfg_changed = false;
2856 unsigned int todoflags = 0;
2860 block_stmt_iterator i;
2861 for (i = bsi_start (bb); !bsi_end_p (i); )
2863 tree *stmtp = bsi_stmt_ptr (i);
2864 tree old_stmt = *stmtp;
2865 tree call = get_rhs (*stmtp);
2866 tree callee, result;
2867 enum built_in_function fcode;
2869 if (!call || TREE_CODE (call) != CALL_EXPR)
2874 callee = get_callee_fndecl (call);
2875 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
2880 fcode = DECL_FUNCTION_CODE (callee);
2882 result = ccp_fold_builtin (*stmtp, call);
2884 switch (DECL_FUNCTION_CODE (callee))
2886 case BUILT_IN_CONSTANT_P:
2887 /* Resolve __builtin_constant_p. If it hasn't been
2888 folded to integer_one_node by now, it's fairly
2889 certain that the value simply isn't constant. */
2890 result = integer_zero_node;
2893 case BUILT_IN_STACK_RESTORE:
2894 result = optimize_stack_restore (bb, *stmtp, i);
2900 case BUILT_IN_VA_START:
2901 case BUILT_IN_VA_END:
2902 case BUILT_IN_VA_COPY:
2903 /* These shouldn't be folded before pass_stdarg. */
2904 result = optimize_stdarg_builtin (*stmtp);
2914 if (dump_file && (dump_flags & TDF_DETAILS))
2916 fprintf (dump_file, "Simplified\n ");
2917 print_generic_stmt (dump_file, *stmtp, dump_flags);
2920 push_stmt_changes (stmtp);
2922 if (!set_rhs (stmtp, result))
2924 result = convert_to_gimple_builtin (&i, result,
2925 TREE_CODE (old_stmt)
2926 != GIMPLE_MODIFY_STMT);
2929 bool ok = set_rhs (stmtp, result);
2931 todoflags |= TODO_rebuild_alias;
2935 pop_stmt_changes (stmtp);
2937 if (maybe_clean_or_replace_eh_stmt (old_stmt, *stmtp)
2938 && tree_purge_dead_eh_edges (bb))
2941 if (dump_file && (dump_flags & TDF_DETAILS))
2943 fprintf (dump_file, "to\n ");
2944 print_generic_stmt (dump_file, *stmtp, dump_flags);
2945 fprintf (dump_file, "\n");
2948 /* Retry the same statement if it changed into another
2949 builtin, there might be new opportunities now. */
2950 call = get_rhs (*stmtp);
2951 if (!call || TREE_CODE (call) != CALL_EXPR)
2956 callee = get_callee_fndecl (call);
2958 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
2959 || DECL_FUNCTION_CODE (callee) == fcode)
2964 /* Delete unreachable blocks. */
2966 todoflags |= TODO_cleanup_cfg;
2972 struct tree_opt_pass pass_fold_builtins =
2976 execute_fold_all_builtins, /* execute */
2979 0, /* static_pass_number */
2981 PROP_cfg | PROP_ssa, /* properties_required */
2982 0, /* properties_provided */
2983 0, /* properties_destroyed */
2984 0, /* todo_flags_start */
2987 | TODO_update_ssa, /* todo_flags_finish */