1 /* Conditional constant propagation pass for the GNU compiler.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
3 Free Software Foundation, Inc.
4 Adapted from original RTL SSA-CCP by Daniel Berlin <dberlin@dberlin.org>
5 Adapted to GIMPLE trees by Diego Novillo <dnovillo@redhat.com>
7 This file is part of GCC.
9 GCC is free software; you can redistribute it and/or modify it
10 under the terms of the GNU General Public License as published by the
11 Free Software Foundation; either version 3, or (at your option) any
14 GCC is distributed in the hope that it will be useful, but WITHOUT
15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
16 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
19 You should have received a copy of the GNU General Public License
20 along with GCC; see the file COPYING3. If not see
21 <http://www.gnu.org/licenses/>. */
23 /* Conditional constant propagation (CCP) is based on the SSA
24 propagation engine (tree-ssa-propagate.c). Constant assignments of
25 the form VAR = CST are propagated from the assignments into uses of
26 VAR, which in turn may generate new constants. The simulation uses
27 a four level lattice to keep track of constant values associated
28 with SSA names. Given an SSA name V_i, it may take one of the
31 UNINITIALIZED -> the initial state of the value. This value
32 is replaced with a correct initial value
33 the first time the value is used, so the
34 rest of the pass does not need to care about
35 it. Using this value simplifies initialization
36 of the pass, and prevents us from needlessly
37 scanning statements that are never reached.
39 UNDEFINED -> V_i is a local variable whose definition
40 has not been processed yet. Therefore we
41 don't yet know if its value is a constant
44 CONSTANT -> V_i has been found to hold a constant
47 VARYING -> V_i cannot take a constant value, or if it
48 does, it is not possible to determine it
51 The core of SSA-CCP is in ccp_visit_stmt and ccp_visit_phi_node:
53 1- In ccp_visit_stmt, we are interested in assignments whose RHS
54 evaluates into a constant and conditional jumps whose predicate
55 evaluates into a boolean true or false. When an assignment of
56 the form V_i = CONST is found, V_i's lattice value is set to
57 CONSTANT and CONST is associated with it. This causes the
58 propagation engine to add all the SSA edges coming out the
59 assignment into the worklists, so that statements that use V_i
62 If the statement is a conditional with a constant predicate, we
63 mark the outgoing edges as executable or not executable
64 depending on the predicate's value. This is then used when
65 visiting PHI nodes to know when a PHI argument can be ignored.
68 2- In ccp_visit_phi_node, if all the PHI arguments evaluate to the
69 same constant C, then the LHS of the PHI is set to C. This
70 evaluation is known as the "meet operation". Since one of the
71 goals of this evaluation is to optimistically return constant
72 values as often as possible, it uses two main short cuts:
74 - If an argument is flowing in through a non-executable edge, it
75 is ignored. This is useful in cases like this:
81 a_11 = PHI (a_9, a_10)
83 If PRED is known to always evaluate to false, then we can
84 assume that a_11 will always take its value from a_10, meaning
85 that instead of consider it VARYING (a_9 and a_10 have
86 different values), we can consider it CONSTANT 100.
88 - If an argument has an UNDEFINED value, then it does not affect
89 the outcome of the meet operation. If a variable V_i has an
90 UNDEFINED value, it means that either its defining statement
91 hasn't been visited yet or V_i has no defining statement, in
92 which case the original symbol 'V' is being used
93 uninitialized. Since 'V' is a local variable, the compiler
94 may assume any initial value for it.
97 After propagation, every variable V_i that ends up with a lattice
98 value of CONSTANT will have the associated constant value in the
99 array CONST_VAL[i].VALUE. That is fed into substitute_and_fold for
100 final substitution and folding.
103 Constant propagation in stores and loads (STORE-CCP)
104 ----------------------------------------------------
106 While CCP has all the logic to propagate constants in GIMPLE
107 registers, it is missing the ability to associate constants with
108 stores and loads (i.e., pointer dereferences, structures and
109 global/aliased variables). We don't keep loads and stores in
110 SSA, but we do build a factored use-def web for them (in the
113 For instance, consider the following code fragment:
132 We should be able to deduce that the predicate 'a.a != B' is always
133 false. To achieve this, we associate constant values to the SSA
134 names in the VDEF operands for each store. Additionally,
135 since we also glob partial loads/stores with the base symbol, we
136 also keep track of the memory reference where the constant value
137 was stored (in the MEM_REF field of PROP_VALUE_T). For instance,
145 In the example above, CCP will associate value '2' with 'a_5', but
146 it would be wrong to replace the load from 'a.b' with '2', because
147 '2' had been stored into a.a.
149 Note that the initial value of virtual operands is VARYING, not
150 UNDEFINED. Consider, for instance global variables:
158 # A_5 = PHI (A_4, A_2);
166 The value of A_2 cannot be assumed to be UNDEFINED, as it may have
167 been defined outside of foo. If we were to assume it UNDEFINED, we
168 would erroneously optimize the above into 'return 3;'.
170 Though STORE-CCP is not too expensive, it does have to do more work
171 than regular CCP, so it is only enabled at -O2. Both regular CCP
172 and STORE-CCP use the exact same algorithm. The only distinction
173 is that when doing STORE-CCP, the boolean variable DO_STORE_CCP is
174 set to true. This affects the evaluation of statements and PHI
179 Constant propagation with conditional branches,
180 Wegman and Zadeck, ACM TOPLAS 13(2):181-210.
182 Building an Optimizing Compiler,
183 Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9.
185 Advanced Compiler Design and Implementation,
186 Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */
190 #include "coretypes.h"
197 #include "basic-block.h"
200 #include "function.h"
201 #include "diagnostic.h"
203 #include "tree-dump.h"
204 #include "tree-flow.h"
205 #include "tree-pass.h"
206 #include "tree-ssa-propagate.h"
207 #include "value-prof.h"
208 #include "langhooks.h"
213 /* Possible lattice values. */
222 /* Array of propagated constant values. After propagation,
223 CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If
224 the constant is held in an SSA name representing a memory store
225 (i.e., a VDEF), CONST_VAL[I].MEM_REF will contain the actual
226 memory reference used to store (i.e., the LHS of the assignment
228 static prop_value_t *const_val;
230 /* True if we are also propagating constants in stores and loads. */
231 static bool do_store_ccp;
233 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */
236 dump_lattice_value (FILE *outf, const char *prefix, prop_value_t val)
238 switch (val.lattice_val)
241 fprintf (outf, "%sUNINITIALIZED", prefix);
244 fprintf (outf, "%sUNDEFINED", prefix);
247 fprintf (outf, "%sVARYING", prefix);
250 fprintf (outf, "%sCONSTANT ", prefix);
251 print_generic_expr (outf, val.value, dump_flags);
259 /* Print lattice value VAL to stderr. */
261 void debug_lattice_value (prop_value_t val);
264 debug_lattice_value (prop_value_t val)
266 dump_lattice_value (stderr, "", val);
267 fprintf (stderr, "\n");
272 /* If SYM is a constant variable with known value, return the value.
273 NULL_TREE is returned otherwise. */
276 get_symbol_constant_value (tree sym)
278 if (TREE_STATIC (sym)
279 && TREE_READONLY (sym)
282 tree val = DECL_INITIAL (sym);
285 STRIP_USELESS_TYPE_CONVERSION (val);
286 if (is_gimple_min_invariant (val))
289 /* Variables declared 'const' without an initializer
290 have zero as the initializer if they may not be
291 overridden at link or run time. */
293 && targetm.binds_local_p (sym)
294 && (INTEGRAL_TYPE_P (TREE_TYPE (sym))
295 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (sym))))
296 return fold_convert (TREE_TYPE (sym), integer_zero_node);
302 /* Compute a default value for variable VAR and store it in the
303 CONST_VAL array. The following rules are used to get default
306 1- Global and static variables that are declared constant are
309 2- Any other value is considered UNDEFINED. This is useful when
310 considering PHI nodes. PHI arguments that are undefined do not
311 change the constant value of the PHI node, which allows for more
312 constants to be propagated.
314 3- Variables defined by statements other than assignments and PHI
315 nodes are considered VARYING.
317 4- Initial values of variables that are not GIMPLE registers are
318 considered VARYING. */
321 get_default_value (tree var)
323 tree sym = SSA_NAME_VAR (var);
324 prop_value_t val = { UNINITIALIZED, NULL_TREE, NULL_TREE };
327 if (!do_store_ccp && !is_gimple_reg (var))
329 /* Short circuit for regular CCP. We are not interested in any
330 non-register when DO_STORE_CCP is false. */
331 val.lattice_val = VARYING;
333 else if ((cst_val = get_symbol_constant_value (sym)) != NULL_TREE)
335 /* Globals and static variables declared 'const' take their
337 val.lattice_val = CONSTANT;
343 gimple stmt = SSA_NAME_DEF_STMT (var);
345 if (gimple_nop_p (stmt))
347 /* Variables defined by an empty statement are those used
348 before being initialized. If VAR is a local variable, we
349 can assume initially that it is UNDEFINED, otherwise we must
350 consider it VARYING. */
351 if (is_gimple_reg (sym) && TREE_CODE (sym) != PARM_DECL)
352 val.lattice_val = UNDEFINED;
354 val.lattice_val = VARYING;
356 else if (is_gimple_assign (stmt)
357 /* Value-returning GIMPLE_CALL statements assign to
358 a variable, and are treated similarly to GIMPLE_ASSIGN. */
359 || (is_gimple_call (stmt)
360 && gimple_call_lhs (stmt) != NULL_TREE)
361 || gimple_code (stmt) == GIMPLE_PHI)
363 /* Any other variable defined by an assignment or a PHI node
364 is considered UNDEFINED. */
365 val.lattice_val = UNDEFINED;
369 /* Otherwise, VAR will never take on a constant value. */
370 val.lattice_val = VARYING;
378 /* Get the constant value associated with variable VAR. */
380 static inline prop_value_t *
385 if (const_val == NULL)
388 val = &const_val[SSA_NAME_VERSION (var)];
389 if (val->lattice_val == UNINITIALIZED)
390 *val = get_default_value (var);
395 /* Sets the value associated with VAR to VARYING. */
398 set_value_varying (tree var)
400 prop_value_t *val = &const_val[SSA_NAME_VERSION (var)];
402 val->lattice_val = VARYING;
403 val->value = NULL_TREE;
404 val->mem_ref = NULL_TREE;
407 /* For float types, modify the value of VAL to make ccp work correctly
408 for non-standard values (-0, NaN):
410 If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0.
411 If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED.
412 This is to fix the following problem (see PR 29921): Suppose we have
416 and we set value of y to NaN. This causes value of x to be set to NaN.
417 When we later determine that y is in fact VARYING, fold uses the fact
418 that HONOR_NANS is false, and we try to change the value of x to 0,
419 causing an ICE. With HONOR_NANS being false, the real appearance of
420 NaN would cause undefined behavior, though, so claiming that y (and x)
421 are UNDEFINED initially is correct. */
424 canonicalize_float_value (prop_value_t *val)
426 enum machine_mode mode;
430 if (val->lattice_val != CONSTANT
431 || TREE_CODE (val->value) != REAL_CST)
434 d = TREE_REAL_CST (val->value);
435 type = TREE_TYPE (val->value);
436 mode = TYPE_MODE (type);
438 if (!HONOR_SIGNED_ZEROS (mode)
439 && REAL_VALUE_MINUS_ZERO (d))
441 val->value = build_real (type, dconst0);
445 if (!HONOR_NANS (mode)
446 && REAL_VALUE_ISNAN (d))
448 val->lattice_val = UNDEFINED;
455 /* Set the value for variable VAR to NEW_VAL. Return true if the new
456 value is different from VAR's previous value. */
459 set_lattice_value (tree var, prop_value_t new_val)
461 prop_value_t *old_val = get_value (var);
463 canonicalize_float_value (&new_val);
465 /* Lattice transitions must always be monotonically increasing in
466 value. If *OLD_VAL and NEW_VAL are the same, return false to
467 inform the caller that this was a non-transition. */
469 gcc_assert (old_val->lattice_val < new_val.lattice_val
470 || (old_val->lattice_val == new_val.lattice_val
471 && ((!old_val->value && !new_val.value)
472 || operand_equal_p (old_val->value, new_val.value, 0))
473 && old_val->mem_ref == new_val.mem_ref));
475 if (old_val->lattice_val != new_val.lattice_val)
477 if (dump_file && (dump_flags & TDF_DETAILS))
479 dump_lattice_value (dump_file, "Lattice value changed to ", new_val);
480 fprintf (dump_file, ". Adding SSA edges to worklist.\n");
485 gcc_assert (new_val.lattice_val != UNDEFINED);
493 /* Return the likely CCP lattice value for STMT.
495 If STMT has no operands, then return CONSTANT.
497 Else if undefinedness of operands of STMT cause its value to be
498 undefined, then return UNDEFINED.
500 Else if any operands of STMT are constants, then return CONSTANT.
502 Else return VARYING. */
505 likely_value (gimple stmt)
507 bool has_constant_operand, has_undefined_operand, all_undefined_operands;
511 enum tree_code code = gimple_code (stmt);
513 /* This function appears to be called only for assignments, calls,
514 conditionals, and switches, due to the logic in visit_stmt. */
515 gcc_assert (code == GIMPLE_ASSIGN
516 || code == GIMPLE_CALL
517 || code == GIMPLE_COND
518 || code == GIMPLE_SWITCH);
520 /* If the statement has volatile operands, it won't fold to a
522 if (gimple_has_volatile_ops (stmt))
525 /* If we are not doing store-ccp, statements with loads
526 and/or stores will never fold into a constant. */
528 && !ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
531 /* Note that only a GIMPLE_SINGLE_RHS assignment can satisfy
532 is_gimple_min_invariant, so we do not consider calls or
533 other forms of assignment. */
534 if (gimple_assign_single_p (stmt)
535 && is_gimple_min_invariant (gimple_assign_rhs1 (stmt)))
538 if (code == GIMPLE_COND
539 && is_gimple_min_invariant (gimple_cond_lhs (stmt))
540 && is_gimple_min_invariant (gimple_cond_rhs (stmt)))
543 if (code == GIMPLE_SWITCH
544 && is_gimple_min_invariant (gimple_switch_index (stmt)))
547 /* Arrive here for more complex cases. */
549 has_constant_operand = false;
550 has_undefined_operand = false;
551 all_undefined_operands = true;
552 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
554 prop_value_t *val = get_value (use);
556 if (val->lattice_val == UNDEFINED)
557 has_undefined_operand = true;
559 all_undefined_operands = false;
561 if (val->lattice_val == CONSTANT)
562 has_constant_operand = true;
565 /* If the operation combines operands like COMPLEX_EXPR make sure to
566 not mark the result UNDEFINED if only one part of the result is
568 if (has_undefined_operand && all_undefined_operands)
570 else if (code == GIMPLE_ASSIGN && has_undefined_operand)
572 switch (gimple_assign_rhs_code (stmt))
574 /* Unary operators are handled with all_undefined_operands. */
577 case POINTER_PLUS_EXPR:
578 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected.
579 Not bitwise operators, one VARYING operand may specify the
580 result completely. Not logical operators for the same reason.
581 Not COMPLEX_EXPR as one VARYING operand makes the result partly
582 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because
583 the undefined operand may be promoted. */
590 /* If there was an UNDEFINED operand but the result may be not UNDEFINED
591 fall back to VARYING even if there were CONSTANT operands. */
592 if (has_undefined_operand)
595 if (has_constant_operand
596 /* We do not consider virtual operands here -- load from read-only
597 memory may have only VARYING virtual operands, but still be
599 || ZERO_SSA_OPERANDS (stmt, SSA_OP_USE))
605 /* Returns true if STMT cannot be constant. */
608 surely_varying_stmt_p (gimple stmt)
610 /* If the statement has operands that we cannot handle, it cannot be
612 if (gimple_has_volatile_ops (stmt))
615 if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
620 /* We can only handle simple loads and stores. */
621 if (!stmt_makes_single_load (stmt)
622 && !stmt_makes_single_store (stmt))
626 /* If it is a call and does not return a value or is not a
627 builtin and not an indirect call, it is varying. */
628 if (is_gimple_call (stmt))
631 if (!gimple_call_lhs (stmt)
632 || ((fndecl = gimple_call_fndecl (stmt)) != NULL_TREE
633 && DECL_BUILT_IN (fndecl)))
637 /* Anything other than assignments and conditional jumps are not
638 interesting for CCP. */
639 if (gimple_code (stmt) != GIMPLE_ASSIGN
640 && gimple_code (stmt) != GIMPLE_COND
641 && gimple_code (stmt) != GIMPLE_SWITCH
642 && gimple_code (stmt) != GIMPLE_CALL)
648 /* Initialize local data structures for CCP. */
651 ccp_initialize (void)
655 const_val = XCNEWVEC (prop_value_t, num_ssa_names);
657 /* Initialize simulation flags for PHI nodes and statements. */
660 gimple_stmt_iterator i;
662 for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i))
664 gimple stmt = gsi_stmt (i);
665 bool is_varying = surely_varying_stmt_p (stmt);
672 /* If the statement will not produce a constant, mark
673 all its outputs VARYING. */
674 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
677 set_value_varying (def);
680 prop_set_simulate_again (stmt, !is_varying);
684 /* Now process PHI nodes. We never clear the simulate_again flag on
685 phi nodes, since we do not know which edges are executable yet,
686 except for phi nodes for virtual operands when we do not do store ccp. */
689 gimple_stmt_iterator i;
691 for (i = gsi_start_phis (bb); !gsi_end_p (i); gsi_next (&i))
693 gimple phi = gsi_stmt (i);
695 if (!do_store_ccp && !is_gimple_reg (gimple_phi_result (phi)))
696 prop_set_simulate_again (phi, false);
698 prop_set_simulate_again (phi, true);
704 /* Do final substitution of propagated values, cleanup the flowgraph and
705 free allocated storage.
707 Return TRUE when something was optimized. */
712 /* Perform substitutions based on the known constant values. */
713 bool something_changed = substitute_and_fold (const_val, false);
717 return something_changed;;
721 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
724 any M UNDEFINED = any
725 any M VARYING = VARYING
726 Ci M Cj = Ci if (i == j)
727 Ci M Cj = VARYING if (i != j)
731 ccp_lattice_meet (prop_value_t *val1, prop_value_t *val2)
733 if (val1->lattice_val == UNDEFINED)
735 /* UNDEFINED M any = any */
738 else if (val2->lattice_val == UNDEFINED)
740 /* any M UNDEFINED = any
741 Nothing to do. VAL1 already contains the value we want. */
744 else if (val1->lattice_val == VARYING
745 || val2->lattice_val == VARYING)
747 /* any M VARYING = VARYING. */
748 val1->lattice_val = VARYING;
749 val1->value = NULL_TREE;
750 val1->mem_ref = NULL_TREE;
752 else if (val1->lattice_val == CONSTANT
753 && val2->lattice_val == CONSTANT
754 && simple_cst_equal (val1->value, val2->value) == 1
756 || (val1->mem_ref && val2->mem_ref
757 && operand_equal_p (val1->mem_ref, val2->mem_ref, 0))))
759 /* Ci M Cj = Ci if (i == j)
760 Ci M Cj = VARYING if (i != j)
762 If these two values come from memory stores, make sure that
763 they come from the same memory reference. */
764 val1->lattice_val = CONSTANT;
765 val1->value = val1->value;
766 val1->mem_ref = val1->mem_ref;
770 /* Any other combination is VARYING. */
771 val1->lattice_val = VARYING;
772 val1->value = NULL_TREE;
773 val1->mem_ref = NULL_TREE;
778 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
779 lattice values to determine PHI_NODE's lattice value. The value of a
780 PHI node is determined calling ccp_lattice_meet with all the arguments
781 of the PHI node that are incoming via executable edges. */
783 static enum ssa_prop_result
784 ccp_visit_phi_node (gimple phi)
787 prop_value_t *old_val, new_val;
789 if (dump_file && (dump_flags & TDF_DETAILS))
791 fprintf (dump_file, "\nVisiting PHI node: ");
792 print_gimple_stmt (dump_file, phi, 0, dump_flags);
795 old_val = get_value (gimple_phi_result (phi));
796 switch (old_val->lattice_val)
799 return SSA_PROP_VARYING;
806 new_val.lattice_val = UNDEFINED;
807 new_val.value = NULL_TREE;
808 new_val.mem_ref = NULL_TREE;
815 for (i = 0; i < gimple_phi_num_args (phi); i++)
817 /* Compute the meet operator over all the PHI arguments flowing
818 through executable edges. */
819 edge e = gimple_phi_arg_edge (phi, i);
821 if (dump_file && (dump_flags & TDF_DETAILS))
824 "\n Argument #%d (%d -> %d %sexecutable)\n",
825 i, e->src->index, e->dest->index,
826 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
829 /* If the incoming edge is executable, Compute the meet operator for
830 the existing value of the PHI node and the current PHI argument. */
831 if (e->flags & EDGE_EXECUTABLE)
833 tree arg = gimple_phi_arg (phi, i)->def;
834 prop_value_t arg_val;
836 if (is_gimple_min_invariant (arg))
838 arg_val.lattice_val = CONSTANT;
840 arg_val.mem_ref = NULL_TREE;
843 arg_val = *(get_value (arg));
845 ccp_lattice_meet (&new_val, &arg_val);
847 if (dump_file && (dump_flags & TDF_DETAILS))
849 fprintf (dump_file, "\t");
850 print_generic_expr (dump_file, arg, dump_flags);
851 dump_lattice_value (dump_file, "\tValue: ", arg_val);
852 fprintf (dump_file, "\n");
855 if (new_val.lattice_val == VARYING)
860 if (dump_file && (dump_flags & TDF_DETAILS))
862 dump_lattice_value (dump_file, "\n PHI node value: ", new_val);
863 fprintf (dump_file, "\n\n");
866 /* Make the transition to the new value. */
867 if (set_lattice_value (gimple_phi_result (phi), new_val))
869 if (new_val.lattice_val == VARYING)
870 return SSA_PROP_VARYING;
872 return SSA_PROP_INTERESTING;
875 return SSA_PROP_NOT_INTERESTING;
879 /* CCP specific front-end to the non-destructive constant folding
882 Attempt to simplify the RHS of STMT knowing that one or more
883 operands are constants.
885 If simplification is possible, return the simplified RHS,
886 otherwise return the original RHS or NULL_TREE. */
889 ccp_fold (gimple stmt)
891 switch (gimple_code (stmt))
895 enum tree_code subcode = gimple_assign_rhs_code (stmt);
897 switch (get_gimple_rhs_class (subcode))
899 case GIMPLE_SINGLE_RHS:
901 tree rhs = gimple_assign_rhs1 (stmt);
902 enum tree_code_class kind = TREE_CODE_CLASS (subcode);
904 if (TREE_CODE (rhs) == SSA_NAME)
906 /* If the RHS is an SSA_NAME, return its known constant value,
908 return get_value (rhs)->value;
910 /* Handle propagating invariant addresses into address operations.
911 The folding we do here matches that in tree-ssa-forwprop.c. */
912 else if (TREE_CODE (rhs) == ADDR_EXPR)
915 base = &TREE_OPERAND (rhs, 0);
916 while (handled_component_p (*base))
917 base = &TREE_OPERAND (*base, 0);
918 if (TREE_CODE (*base) == INDIRECT_REF
919 && TREE_CODE (TREE_OPERAND (*base, 0)) == SSA_NAME)
921 prop_value_t *val = get_value (TREE_OPERAND (*base, 0));
922 if (val->lattice_val == CONSTANT
923 && TREE_CODE (val->value) == ADDR_EXPR
924 && useless_type_conversion_p
925 (TREE_TYPE (TREE_OPERAND (*base, 0)),
926 TREE_TYPE (val->value))
927 && useless_type_conversion_p
929 TREE_TYPE (TREE_OPERAND (val->value, 0))))
931 /* We need to return a new tree, not modify the IL
932 or share parts of it. So play some tricks to
933 avoid manually building it. */
934 tree ret, save = *base;
935 *base = TREE_OPERAND (val->value, 0);
936 ret = unshare_expr (rhs);
937 recompute_tree_invariant_for_addr_expr (ret);
944 else if (do_store_ccp && stmt_makes_single_load (stmt))
946 /* If the RHS is a memory load, see if the VUSEs associated with
947 it are a valid constant for that memory load. */
948 prop_value_t *val = get_value_loaded_by (stmt, const_val);
949 if (val && val->mem_ref)
951 if (operand_equal_p (val->mem_ref, rhs, 0))
954 /* If RHS is extracting REALPART_EXPR or IMAGPART_EXPR of a
955 complex type with a known constant value, return it. */
956 if ((TREE_CODE (rhs) == REALPART_EXPR
957 || TREE_CODE (rhs) == IMAGPART_EXPR)
958 && operand_equal_p (val->mem_ref, TREE_OPERAND (rhs, 0), 0))
959 return fold_build1 (TREE_CODE (rhs), TREE_TYPE (rhs), val->value);
963 if (kind == tcc_reference)
964 return fold_const_aggregate_ref (rhs);
965 else if (kind == tcc_declaration)
966 return get_symbol_constant_value (rhs);
970 case GIMPLE_UNARY_RHS:
972 /* Handle unary operators that can appear in GIMPLE form.
973 Note that we know the single operand must be a constant,
974 so this should almost always return a simplified RHS. */
975 tree lhs = gimple_assign_lhs (stmt);
976 tree op0 = gimple_assign_rhs1 (stmt);
978 /* Simplify the operand down to a constant. */
979 if (TREE_CODE (op0) == SSA_NAME)
981 prop_value_t *val = get_value (op0);
982 if (val->lattice_val == CONSTANT)
983 op0 = get_value (op0)->value;
986 /* Conversions are useless for CCP purposes if they are
987 value-preserving. Thus the restrictions that
988 useless_type_conversion_p places for pointer type conversions
989 do not apply here. Substitution later will only substitute to
991 if ((subcode == NOP_EXPR || subcode == CONVERT_EXPR)
992 && ((POINTER_TYPE_P (TREE_TYPE (lhs))
993 && POINTER_TYPE_P (TREE_TYPE (op0))
994 /* Do not allow differences in volatile qualification
995 as this might get us confused as to whether a
996 propagation destination statement is volatile
997 or not. See PR36988. */
998 && (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (lhs)))
999 == TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (op0)))))
1000 || useless_type_conversion_p (TREE_TYPE (lhs),
1004 return fold_unary (subcode, gimple_expr_type (stmt), op0);
1007 case GIMPLE_BINARY_RHS:
1009 /* Handle binary operators that can appear in GIMPLE form. */
1010 tree op0 = gimple_assign_rhs1 (stmt);
1011 tree op1 = gimple_assign_rhs2 (stmt);
1013 /* Simplify the operands down to constants when appropriate. */
1014 if (TREE_CODE (op0) == SSA_NAME)
1016 prop_value_t *val = get_value (op0);
1017 if (val->lattice_val == CONSTANT)
1021 if (TREE_CODE (op1) == SSA_NAME)
1023 prop_value_t *val = get_value (op1);
1024 if (val->lattice_val == CONSTANT)
1028 return fold_binary (subcode, gimple_expr_type (stmt), op0, op1);
1039 tree fn = gimple_call_fn (stmt);
1042 if (TREE_CODE (fn) == SSA_NAME)
1044 val = get_value (fn);
1045 if (val->lattice_val == CONSTANT)
1048 if (TREE_CODE (fn) == ADDR_EXPR
1049 && DECL_BUILT_IN (TREE_OPERAND (fn, 0)))
1051 tree *args = XALLOCAVEC (tree, gimple_call_num_args (stmt));
1054 for (i = 0; i < gimple_call_num_args (stmt); ++i)
1056 args[i] = gimple_call_arg (stmt, i);
1057 if (TREE_CODE (args[i]) == SSA_NAME)
1059 val = get_value (args[i]);
1060 if (val->lattice_val == CONSTANT)
1061 args[i] = val->value;
1064 call = build_call_array (gimple_call_return_type (stmt),
1065 fn, gimple_call_num_args (stmt), args);
1066 retval = fold_call_expr (call, false);
1068 /* fold_call_expr wraps the result inside a NOP_EXPR. */
1069 STRIP_NOPS (retval);
1077 /* Handle comparison operators that can appear in GIMPLE form. */
1078 tree op0 = gimple_cond_lhs (stmt);
1079 tree op1 = gimple_cond_rhs (stmt);
1080 enum tree_code code = gimple_cond_code (stmt);
1082 /* Simplify the operands down to constants when appropriate. */
1083 if (TREE_CODE (op0) == SSA_NAME)
1085 prop_value_t *val = get_value (op0);
1086 if (val->lattice_val == CONSTANT)
1090 if (TREE_CODE (op1) == SSA_NAME)
1092 prop_value_t *val = get_value (op1);
1093 if (val->lattice_val == CONSTANT)
1097 return fold_binary (code, boolean_type_node, op0, op1);
1102 tree rhs = gimple_switch_index (stmt);
1104 if (TREE_CODE (rhs) == SSA_NAME)
1106 /* If the RHS is an SSA_NAME, return its known constant value,
1108 return get_value (rhs)->value;
1120 /* Return the tree representing the element referenced by T if T is an
1121 ARRAY_REF or COMPONENT_REF into constant aggregates. Return
1122 NULL_TREE otherwise. */
1125 fold_const_aggregate_ref (tree t)
1127 prop_value_t *value;
1128 tree base, ctor, idx, field;
1129 unsigned HOST_WIDE_INT cnt;
1132 switch (TREE_CODE (t))
1135 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1136 DECL_INITIAL. If BASE is a nested reference into another
1137 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1138 the inner reference. */
1139 base = TREE_OPERAND (t, 0);
1140 switch (TREE_CODE (base))
1143 if (!TREE_READONLY (base)
1144 || TREE_CODE (TREE_TYPE (base)) != ARRAY_TYPE
1145 || !targetm.binds_local_p (base))
1148 ctor = DECL_INITIAL (base);
1153 ctor = fold_const_aggregate_ref (base);
1165 if (ctor == NULL_TREE
1166 || (TREE_CODE (ctor) != CONSTRUCTOR
1167 && TREE_CODE (ctor) != STRING_CST)
1168 || !TREE_STATIC (ctor))
1171 /* Get the index. If we have an SSA_NAME, try to resolve it
1172 with the current lattice value for the SSA_NAME. */
1173 idx = TREE_OPERAND (t, 1);
1174 switch (TREE_CODE (idx))
1177 if ((value = get_value (idx))
1178 && value->lattice_val == CONSTANT
1179 && TREE_CODE (value->value) == INTEGER_CST)
1192 /* Fold read from constant string. */
1193 if (TREE_CODE (ctor) == STRING_CST)
1195 if ((TYPE_MODE (TREE_TYPE (t))
1196 == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1197 && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1199 && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) == 1
1200 && compare_tree_int (idx, TREE_STRING_LENGTH (ctor)) < 0)
1201 return build_int_cst_type (TREE_TYPE (t),
1202 (TREE_STRING_POINTER (ctor)
1203 [TREE_INT_CST_LOW (idx)]));
1207 /* Whoo-hoo! I'll fold ya baby. Yeah! */
1208 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
1209 if (tree_int_cst_equal (cfield, idx))
1211 STRIP_USELESS_TYPE_CONVERSION (cval);
1217 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1218 DECL_INITIAL. If BASE is a nested reference into another
1219 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1220 the inner reference. */
1221 base = TREE_OPERAND (t, 0);
1222 switch (TREE_CODE (base))
1225 if (!TREE_READONLY (base)
1226 || TREE_CODE (TREE_TYPE (base)) != RECORD_TYPE
1227 || !targetm.binds_local_p (base))
1230 ctor = DECL_INITIAL (base);
1235 ctor = fold_const_aggregate_ref (base);
1242 if (ctor == NULL_TREE
1243 || TREE_CODE (ctor) != CONSTRUCTOR
1244 || !TREE_STATIC (ctor))
1247 field = TREE_OPERAND (t, 1);
1249 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
1251 /* FIXME: Handle bit-fields. */
1252 && ! DECL_BIT_FIELD (cfield))
1254 STRIP_USELESS_TYPE_CONVERSION (cval);
1262 tree c = fold_const_aggregate_ref (TREE_OPERAND (t, 0));
1263 if (c && TREE_CODE (c) == COMPLEX_CST)
1264 return fold_build1 (TREE_CODE (t), TREE_TYPE (t), c);
1270 tree base = TREE_OPERAND (t, 0);
1271 if (TREE_CODE (base) == SSA_NAME
1272 && (value = get_value (base))
1273 && value->lattice_val == CONSTANT
1274 && TREE_CODE (value->value) == ADDR_EXPR)
1275 return fold_const_aggregate_ref (TREE_OPERAND (value->value, 0));
1286 /* Evaluate statement STMT.
1287 Valid only for assignments, calls, conditionals, and switches. */
1290 evaluate_stmt (gimple stmt)
1293 tree simplified = NULL_TREE;
1294 ccp_lattice_t likelyvalue = likely_value (stmt);
1297 val.mem_ref = NULL_TREE;
1299 fold_defer_overflow_warnings ();
1301 /* If the statement is likely to have a CONSTANT result, then try
1302 to fold the statement to determine the constant value. */
1303 /* FIXME. This is the only place that we call ccp_fold.
1304 Since likely_value never returns CONSTANT for calls, we will
1305 not attempt to fold them, including builtins that may profit. */
1306 if (likelyvalue == CONSTANT)
1307 simplified = ccp_fold (stmt);
1308 /* If the statement is likely to have a VARYING result, then do not
1309 bother folding the statement. */
1310 else if (likelyvalue == VARYING)
1312 enum tree_code code = gimple_code (stmt);
1313 if (code == GIMPLE_ASSIGN)
1315 enum tree_code subcode = gimple_assign_rhs_code (stmt);
1317 /* Other cases cannot satisfy is_gimple_min_invariant
1319 if (get_gimple_rhs_class (subcode) == GIMPLE_SINGLE_RHS)
1320 simplified = gimple_assign_rhs1 (stmt);
1322 else if (code == GIMPLE_SWITCH)
1323 simplified = gimple_switch_index (stmt);
1325 /* These cannot satisfy is_gimple_min_invariant without folding. */
1326 gcc_assert (code == GIMPLE_CALL || code == GIMPLE_COND);
1329 is_constant = simplified && is_gimple_min_invariant (simplified);
1331 fold_undefer_overflow_warnings (is_constant, stmt, 0);
1333 if (dump_file && (dump_flags & TDF_DETAILS))
1335 fprintf (dump_file, "which is likely ");
1336 switch (likelyvalue)
1339 fprintf (dump_file, "CONSTANT");
1342 fprintf (dump_file, "UNDEFINED");
1345 fprintf (dump_file, "VARYING");
1349 fprintf (dump_file, "\n");
1354 /* The statement produced a constant value. */
1355 val.lattice_val = CONSTANT;
1356 val.value = simplified;
1360 /* The statement produced a nonconstant value. If the statement
1361 had UNDEFINED operands, then the result of the statement
1362 should be UNDEFINED. Otherwise, the statement is VARYING. */
1363 if (likelyvalue == UNDEFINED)
1364 val.lattice_val = likelyvalue;
1366 val.lattice_val = VARYING;
1368 val.value = NULL_TREE;
1374 /* Visit the assignment statement STMT. Set the value of its LHS to the
1375 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
1376 creates virtual definitions, set the value of each new name to that
1377 of the RHS (if we can derive a constant out of the RHS).
1378 Value-returning call statements also perform an assignment, and
1379 are handled here. */
1381 static enum ssa_prop_result
1382 visit_assignment (gimple stmt, tree *output_p)
1385 enum ssa_prop_result retval;
1387 tree lhs = gimple_get_lhs (stmt);
1389 gcc_assert (gimple_code (stmt) != GIMPLE_CALL
1390 || gimple_call_lhs (stmt) != NULL_TREE);
1392 if (gimple_assign_copy_p (stmt))
1394 tree rhs = gimple_assign_rhs1 (stmt);
1396 if (TREE_CODE (rhs) == SSA_NAME)
1398 /* For a simple copy operation, we copy the lattice values. */
1399 prop_value_t *nval = get_value (rhs);
1402 else if (do_store_ccp && stmt_makes_single_load (stmt))
1404 /* Same as above, but the RHS is not a gimple register and yet
1405 has a known VUSE. If STMT is loading from the same memory
1406 location that created the SSA_NAMEs for the virtual operands,
1407 we can propagate the value on the RHS. */
1408 prop_value_t *nval = get_value_loaded_by (stmt, const_val);
1412 && operand_equal_p (nval->mem_ref, rhs, 0))
1415 val = evaluate_stmt (stmt);
1418 val = evaluate_stmt (stmt);
1421 /* Evaluate the statement, which could be
1422 either a GIMPLE_ASSIGN or a GIMPLE_CALL. */
1423 val = evaluate_stmt (stmt);
1425 retval = SSA_PROP_NOT_INTERESTING;
1427 /* Set the lattice value of the statement's output. */
1428 if (TREE_CODE (lhs) == SSA_NAME)
1430 /* If STMT is an assignment to an SSA_NAME, we only have one
1432 if (set_lattice_value (lhs, val))
1435 if (val.lattice_val == VARYING)
1436 retval = SSA_PROP_VARYING;
1438 retval = SSA_PROP_INTERESTING;
1441 else if (do_store_ccp && stmt_makes_single_store (stmt))
1443 /* Otherwise, set the names in VDEF operands to the new
1444 constant value and mark the LHS as the memory reference
1445 associated with VAL. */
1450 /* Mark VAL as stored in the LHS of this assignment. */
1451 if (val.lattice_val == CONSTANT)
1454 /* Set the value of every VDEF to VAL. */
1456 FOR_EACH_SSA_TREE_OPERAND (vdef, stmt, i, SSA_OP_VIRTUAL_DEFS)
1458 /* See PR 29801. We may have VDEFs for read-only variables
1459 (see the handling of unmodifiable variables in
1460 add_virtual_operand); do not attempt to change their value. */
1461 if (get_symbol_constant_value (SSA_NAME_VAR (vdef)) != NULL_TREE)
1464 changed |= set_lattice_value (vdef, val);
1467 /* Note that for propagation purposes, we are only interested in
1468 visiting statements that load the exact same memory reference
1469 stored here. Those statements will have the exact same list
1470 of virtual uses, so it is enough to set the output of this
1471 statement to be its first virtual definition. */
1472 *output_p = first_vdef (stmt);
1475 if (val.lattice_val == VARYING)
1476 retval = SSA_PROP_VARYING;
1478 retval = SSA_PROP_INTERESTING;
1486 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
1487 if it can determine which edge will be taken. Otherwise, return
1488 SSA_PROP_VARYING. */
1490 static enum ssa_prop_result
1491 visit_cond_stmt (gimple stmt, edge *taken_edge_p)
1496 block = gimple_bb (stmt);
1497 val = evaluate_stmt (stmt);
1499 /* Find which edge out of the conditional block will be taken and add it
1500 to the worklist. If no single edge can be determined statically,
1501 return SSA_PROP_VARYING to feed all the outgoing edges to the
1502 propagation engine. */
1503 *taken_edge_p = val.value ? find_taken_edge (block, val.value) : 0;
1505 return SSA_PROP_INTERESTING;
1507 return SSA_PROP_VARYING;
1511 /* Evaluate statement STMT. If the statement produces an output value and
1512 its evaluation changes the lattice value of its output, return
1513 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
1516 If STMT is a conditional branch and we can determine its truth
1517 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
1518 value, return SSA_PROP_VARYING. */
1520 static enum ssa_prop_result
1521 ccp_visit_stmt (gimple stmt, edge *taken_edge_p, tree *output_p)
1526 if (dump_file && (dump_flags & TDF_DETAILS))
1528 fprintf (dump_file, "\nVisiting statement:\n");
1529 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
1532 switch (gimple_code (stmt))
1535 /* If the statement is an assignment that produces a single
1536 output value, evaluate its RHS to see if the lattice value of
1537 its output has changed. */
1538 return visit_assignment (stmt, output_p);
1541 /* A value-returning call also performs an assignment. */
1542 if (gimple_call_lhs (stmt) != NULL_TREE)
1543 return visit_assignment (stmt, output_p);
1548 /* If STMT is a conditional branch, see if we can determine
1549 which branch will be taken. */
1550 /* FIXME. It appears that we should be able to optimize
1551 computed GOTOs here as well. */
1552 return visit_cond_stmt (stmt, taken_edge_p);
1558 /* Any other kind of statement is not interesting for constant
1559 propagation and, therefore, not worth simulating. */
1560 if (dump_file && (dump_flags & TDF_DETAILS))
1561 fprintf (dump_file, "No interesting values produced. Marked VARYING.\n");
1563 /* Definitions made by statements other than assignments to
1564 SSA_NAMEs represent unknown modifications to their outputs.
1565 Mark them VARYING. */
1566 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
1568 prop_value_t v = { VARYING, NULL_TREE, NULL_TREE };
1569 set_lattice_value (def, v);
1572 return SSA_PROP_VARYING;
1576 /* Main entry point for SSA Conditional Constant Propagation. */
1579 execute_ssa_ccp (bool store_ccp)
1581 do_store_ccp = store_ccp;
1583 ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node);
1584 if (ccp_finalize ())
1585 return (TODO_cleanup_cfg | TODO_update_ssa | TODO_remove_unused_locals);
1594 return execute_ssa_ccp (false);
1601 return flag_tree_ccp != 0;
1605 struct gimple_opt_pass pass_ccp =
1610 gate_ccp, /* gate */
1611 do_ssa_ccp, /* execute */
1614 0, /* static_pass_number */
1615 TV_TREE_CCP, /* tv_id */
1616 PROP_cfg | PROP_ssa, /* properties_required */
1617 0, /* properties_provided */
1618 0, /* properties_destroyed */
1619 0, /* todo_flags_start */
1620 TODO_dump_func | TODO_verify_ssa
1621 | TODO_verify_stmts | TODO_ggc_collect/* todo_flags_finish */
1627 do_ssa_store_ccp (void)
1629 /* If STORE-CCP is not enabled, we just run regular CCP. */
1630 return execute_ssa_ccp (flag_tree_store_ccp != 0);
1634 gate_store_ccp (void)
1636 /* STORE-CCP is enabled only with -ftree-store-ccp, but when
1637 -fno-tree-store-ccp is specified, we should run regular CCP.
1638 That's why the pass is enabled with either flag. */
1639 return flag_tree_store_ccp != 0 || flag_tree_ccp != 0;
1643 struct gimple_opt_pass pass_store_ccp =
1647 "store_ccp", /* name */
1648 gate_store_ccp, /* gate */
1649 do_ssa_store_ccp, /* execute */
1652 0, /* static_pass_number */
1653 TV_TREE_STORE_CCP, /* tv_id */
1654 PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
1655 0, /* properties_provided */
1656 0, /* properties_destroyed */
1657 0, /* todo_flags_start */
1658 TODO_dump_func | TODO_verify_ssa
1659 | TODO_verify_stmts | TODO_ggc_collect/* todo_flags_finish */
1663 /* A subroutine of fold_stmt_r. Attempts to fold *(A+O) to A[X].
1664 BASE is an array type. OFFSET is a byte displacement. ORIG_TYPE
1665 is the desired result type. */
1668 maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type,
1669 bool allow_negative_idx)
1671 tree min_idx, idx, idx_type, elt_offset = integer_zero_node;
1672 tree array_type, elt_type, elt_size;
1675 /* If BASE is an ARRAY_REF, we can pick up another offset (this time
1676 measured in units of the size of elements type) from that ARRAY_REF).
1677 We can't do anything if either is variable.
1679 The case we handle here is *(&A[N]+O). */
1680 if (TREE_CODE (base) == ARRAY_REF)
1682 tree low_bound = array_ref_low_bound (base);
1684 elt_offset = TREE_OPERAND (base, 1);
1685 if (TREE_CODE (low_bound) != INTEGER_CST
1686 || TREE_CODE (elt_offset) != INTEGER_CST)
1689 elt_offset = int_const_binop (MINUS_EXPR, elt_offset, low_bound, 0);
1690 base = TREE_OPERAND (base, 0);
1693 /* Ignore stupid user tricks of indexing non-array variables. */
1694 array_type = TREE_TYPE (base);
1695 if (TREE_CODE (array_type) != ARRAY_TYPE)
1697 elt_type = TREE_TYPE (array_type);
1698 if (!useless_type_conversion_p (orig_type, elt_type))
1701 /* Use signed size type for intermediate computation on the index. */
1702 idx_type = signed_type_for (size_type_node);
1704 /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the
1705 element type (so we can use the alignment if it's not constant).
1706 Otherwise, compute the offset as an index by using a division. If the
1707 division isn't exact, then don't do anything. */
1708 elt_size = TYPE_SIZE_UNIT (elt_type);
1711 if (integer_zerop (offset))
1713 if (TREE_CODE (elt_size) != INTEGER_CST)
1714 elt_size = size_int (TYPE_ALIGN (elt_type));
1716 idx = build_int_cst (idx_type, 0);
1720 unsigned HOST_WIDE_INT lquo, lrem;
1721 HOST_WIDE_INT hquo, hrem;
1724 /* The final array offset should be signed, so we need
1725 to sign-extend the (possibly pointer) offset here
1726 and use signed division. */
1727 soffset = double_int_sext (tree_to_double_int (offset),
1728 TYPE_PRECISION (TREE_TYPE (offset)));
1729 if (TREE_CODE (elt_size) != INTEGER_CST
1730 || div_and_round_double (TRUNC_DIV_EXPR, 0,
1731 soffset.low, soffset.high,
1732 TREE_INT_CST_LOW (elt_size),
1733 TREE_INT_CST_HIGH (elt_size),
1734 &lquo, &hquo, &lrem, &hrem)
1738 idx = build_int_cst_wide (idx_type, lquo, hquo);
1741 /* Assume the low bound is zero. If there is a domain type, get the
1742 low bound, if any, convert the index into that type, and add the
1744 min_idx = build_int_cst (idx_type, 0);
1745 domain_type = TYPE_DOMAIN (array_type);
1748 idx_type = domain_type;
1749 if (TYPE_MIN_VALUE (idx_type))
1750 min_idx = TYPE_MIN_VALUE (idx_type);
1752 min_idx = fold_convert (idx_type, min_idx);
1754 if (TREE_CODE (min_idx) != INTEGER_CST)
1757 elt_offset = fold_convert (idx_type, elt_offset);
1760 if (!integer_zerop (min_idx))
1761 idx = int_const_binop (PLUS_EXPR, idx, min_idx, 0);
1762 if (!integer_zerop (elt_offset))
1763 idx = int_const_binop (PLUS_EXPR, idx, elt_offset, 0);
1765 /* Make sure to possibly truncate late after offsetting. */
1766 idx = fold_convert (idx_type, idx);
1768 /* We don't want to construct access past array bounds. For example
1771 should not be simplified into (*c)[14] or tree-vrp will
1772 give false warnings. The same is true for
1773 struct A { long x; char d[0]; } *a;
1775 which should be not folded to &a->d[-8]. */
1777 && TYPE_MAX_VALUE (domain_type)
1778 && TREE_CODE (TYPE_MAX_VALUE (domain_type)) == INTEGER_CST)
1780 tree up_bound = TYPE_MAX_VALUE (domain_type);
1782 if (tree_int_cst_lt (up_bound, idx)
1783 /* Accesses after the end of arrays of size 0 (gcc
1784 extension) and 1 are likely intentional ("struct
1786 && compare_tree_int (up_bound, 1) > 0)
1790 && TYPE_MIN_VALUE (domain_type))
1792 if (!allow_negative_idx
1793 && TREE_CODE (TYPE_MIN_VALUE (domain_type)) == INTEGER_CST
1794 && tree_int_cst_lt (idx, TYPE_MIN_VALUE (domain_type)))
1797 else if (!allow_negative_idx
1798 && compare_tree_int (idx, 0) < 0)
1801 return build4 (ARRAY_REF, elt_type, base, idx, NULL_TREE, NULL_TREE);
1805 /* Attempt to fold *(S+O) to S.X.
1806 BASE is a record type. OFFSET is a byte displacement. ORIG_TYPE
1807 is the desired result type. */
1810 maybe_fold_offset_to_component_ref (tree record_type, tree base, tree offset,
1811 tree orig_type, bool base_is_ptr)
1813 tree f, t, field_type, tail_array_field, field_offset;
1817 if (TREE_CODE (record_type) != RECORD_TYPE
1818 && TREE_CODE (record_type) != UNION_TYPE
1819 && TREE_CODE (record_type) != QUAL_UNION_TYPE)
1822 /* Short-circuit silly cases. */
1823 if (useless_type_conversion_p (record_type, orig_type))
1826 tail_array_field = NULL_TREE;
1827 for (f = TYPE_FIELDS (record_type); f ; f = TREE_CHAIN (f))
1831 if (TREE_CODE (f) != FIELD_DECL)
1833 if (DECL_BIT_FIELD (f))
1836 if (!DECL_FIELD_OFFSET (f))
1838 field_offset = byte_position (f);
1839 if (TREE_CODE (field_offset) != INTEGER_CST)
1842 /* ??? Java creates "interesting" fields for representing base classes.
1843 They have no name, and have no context. With no context, we get into
1844 trouble with nonoverlapping_component_refs_p. Skip them. */
1845 if (!DECL_FIELD_CONTEXT (f))
1848 /* The previous array field isn't at the end. */
1849 tail_array_field = NULL_TREE;
1851 /* Check to see if this offset overlaps with the field. */
1852 cmp = tree_int_cst_compare (field_offset, offset);
1856 field_type = TREE_TYPE (f);
1858 /* Here we exactly match the offset being checked. If the types match,
1859 then we can return that field. */
1861 && useless_type_conversion_p (orig_type, field_type))
1864 base = build1 (INDIRECT_REF, record_type, base);
1865 t = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE);
1869 /* Don't care about offsets into the middle of scalars. */
1870 if (!AGGREGATE_TYPE_P (field_type))
1873 /* Check for array at the end of the struct. This is often
1874 used as for flexible array members. We should be able to
1875 turn this into an array access anyway. */
1876 if (TREE_CODE (field_type) == ARRAY_TYPE)
1877 tail_array_field = f;
1879 /* Check the end of the field against the offset. */
1880 if (!DECL_SIZE_UNIT (f)
1881 || TREE_CODE (DECL_SIZE_UNIT (f)) != INTEGER_CST)
1883 t = int_const_binop (MINUS_EXPR, offset, field_offset, 1);
1884 if (!tree_int_cst_lt (t, DECL_SIZE_UNIT (f)))
1887 /* If we matched, then set offset to the displacement into
1890 new_base = build1 (INDIRECT_REF, record_type, base);
1893 new_base = build3 (COMPONENT_REF, field_type, new_base, f, NULL_TREE);
1895 /* Recurse to possibly find the match. */
1896 ret = maybe_fold_offset_to_array_ref (new_base, t, orig_type,
1897 f == TYPE_FIELDS (record_type));
1900 ret = maybe_fold_offset_to_component_ref (field_type, new_base, t,
1906 if (!tail_array_field)
1909 f = tail_array_field;
1910 field_type = TREE_TYPE (f);
1911 offset = int_const_binop (MINUS_EXPR, offset, byte_position (f), 1);
1913 /* If we get here, we've got an aggregate field, and a possibly
1914 nonzero offset into them. Recurse and hope for a valid match. */
1916 base = build1 (INDIRECT_REF, record_type, base);
1917 base = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE);
1919 t = maybe_fold_offset_to_array_ref (base, offset, orig_type,
1920 f == TYPE_FIELDS (record_type));
1923 return maybe_fold_offset_to_component_ref (field_type, base, offset,
1927 /* Attempt to express (ORIG_TYPE)BASE+OFFSET as BASE->field_of_orig_type
1928 or BASE[index] or by combination of those.
1930 Before attempting the conversion strip off existing ADDR_EXPRs and
1931 handled component refs. */
1934 maybe_fold_offset_to_reference (tree base, tree offset, tree orig_type)
1938 bool base_is_ptr = true;
1941 if (TREE_CODE (base) == ADDR_EXPR)
1943 base_is_ptr = false;
1945 base = TREE_OPERAND (base, 0);
1947 /* Handle case where existing COMPONENT_REF pick e.g. wrong field of union,
1948 so it needs to be removed and new COMPONENT_REF constructed.
1949 The wrong COMPONENT_REF are often constructed by folding the
1950 (type *)&object within the expression (type *)&object+offset */
1951 if (handled_component_p (base) && 0)
1953 HOST_WIDE_INT sub_offset, size, maxsize;
1955 newbase = get_ref_base_and_extent (base, &sub_offset,
1957 gcc_assert (newbase);
1958 gcc_assert (!(sub_offset & (BITS_PER_UNIT - 1)));
1959 if (size == maxsize)
1963 offset = int_const_binop (PLUS_EXPR, offset,
1964 build_int_cst (TREE_TYPE (offset),
1965 sub_offset / BITS_PER_UNIT), 1);
1968 if (useless_type_conversion_p (orig_type, TREE_TYPE (base))
1969 && integer_zerop (offset))
1971 type = TREE_TYPE (base);
1976 if (!POINTER_TYPE_P (TREE_TYPE (base)))
1978 type = TREE_TYPE (TREE_TYPE (base));
1980 ret = maybe_fold_offset_to_component_ref (type, base, offset,
1981 orig_type, base_is_ptr);
1985 base = build1 (INDIRECT_REF, type, base);
1986 ret = maybe_fold_offset_to_array_ref (base, offset, orig_type, true);
1991 /* A subroutine of fold_stmt_r. Attempt to simplify *(BASE+OFFSET).
1992 Return the simplified expression, or NULL if nothing could be done. */
1995 maybe_fold_stmt_indirect (tree expr, tree base, tree offset)
1998 bool volatile_p = TREE_THIS_VOLATILE (expr);
2000 /* We may well have constructed a double-nested PLUS_EXPR via multiple
2001 substitutions. Fold that down to one. Remove NON_LVALUE_EXPRs that
2002 are sometimes added. */
2004 STRIP_TYPE_NOPS (base);
2005 TREE_OPERAND (expr, 0) = base;
2007 /* One possibility is that the address reduces to a string constant. */
2008 t = fold_read_from_constant_string (expr);
2012 /* Add in any offset from a POINTER_PLUS_EXPR. */
2013 if (TREE_CODE (base) == POINTER_PLUS_EXPR)
2017 offset2 = TREE_OPERAND (base, 1);
2018 if (TREE_CODE (offset2) != INTEGER_CST)
2020 base = TREE_OPERAND (base, 0);
2022 offset = fold_convert (sizetype,
2023 int_const_binop (PLUS_EXPR, offset, offset2, 1));
2026 if (TREE_CODE (base) == ADDR_EXPR)
2028 tree base_addr = base;
2030 /* Strip the ADDR_EXPR. */
2031 base = TREE_OPERAND (base, 0);
2033 /* Fold away CONST_DECL to its value, if the type is scalar. */
2034 if (TREE_CODE (base) == CONST_DECL
2035 && is_gimple_min_invariant (DECL_INITIAL (base)))
2036 return DECL_INITIAL (base);
2038 /* Try folding *(&B+O) to B.X. */
2039 t = maybe_fold_offset_to_reference (base_addr, offset,
2043 TREE_THIS_VOLATILE (t) = volatile_p;
2049 /* We can get here for out-of-range string constant accesses,
2050 such as "_"[3]. Bail out of the entire substitution search
2051 and arrange for the entire statement to be replaced by a
2052 call to __builtin_trap. In all likelihood this will all be
2053 constant-folded away, but in the meantime we can't leave with
2054 something that get_expr_operands can't understand. */
2058 if (TREE_CODE (t) == ADDR_EXPR
2059 && TREE_CODE (TREE_OPERAND (t, 0)) == STRING_CST)
2061 /* FIXME: Except that this causes problems elsewhere with dead
2062 code not being deleted, and we die in the rtl expanders
2063 because we failed to remove some ssa_name. In the meantime,
2064 just return zero. */
2065 /* FIXME2: This condition should be signaled by
2066 fold_read_from_constant_string directly, rather than
2067 re-checking for it here. */
2068 return integer_zero_node;
2071 /* Try folding *(B+O) to B->X. Still an improvement. */
2072 if (POINTER_TYPE_P (TREE_TYPE (base)))
2074 t = maybe_fold_offset_to_reference (base, offset,
2081 /* Otherwise we had an offset that we could not simplify. */
2086 /* A quaint feature extant in our address arithmetic is that there
2087 can be hidden type changes here. The type of the result need
2088 not be the same as the type of the input pointer.
2090 What we're after here is an expression of the form
2091 (T *)(&array + const)
2092 where array is OP0, const is OP1, RES_TYPE is T and
2093 the cast doesn't actually exist, but is implicit in the
2094 type of the POINTER_PLUS_EXPR. We'd like to turn this into
2096 which may be able to propagate further. */
2099 maybe_fold_stmt_addition (tree res_type, tree op0, tree op1)
2104 /* It had better be a constant. */
2105 if (TREE_CODE (op1) != INTEGER_CST)
2107 /* The first operand should be an ADDR_EXPR. */
2108 if (TREE_CODE (op0) != ADDR_EXPR)
2110 op0 = TREE_OPERAND (op0, 0);
2112 /* If the first operand is an ARRAY_REF, expand it so that we can fold
2113 the offset into it. */
2114 while (TREE_CODE (op0) == ARRAY_REF)
2116 tree array_obj = TREE_OPERAND (op0, 0);
2117 tree array_idx = TREE_OPERAND (op0, 1);
2118 tree elt_type = TREE_TYPE (op0);
2119 tree elt_size = TYPE_SIZE_UNIT (elt_type);
2122 if (TREE_CODE (array_idx) != INTEGER_CST)
2124 if (TREE_CODE (elt_size) != INTEGER_CST)
2127 /* Un-bias the index by the min index of the array type. */
2128 min_idx = TYPE_DOMAIN (TREE_TYPE (array_obj));
2131 min_idx = TYPE_MIN_VALUE (min_idx);
2134 if (TREE_CODE (min_idx) != INTEGER_CST)
2137 array_idx = fold_convert (TREE_TYPE (min_idx), array_idx);
2138 if (!integer_zerop (min_idx))
2139 array_idx = int_const_binop (MINUS_EXPR, array_idx,
2144 /* Convert the index to a byte offset. */
2145 array_idx = fold_convert (sizetype, array_idx);
2146 array_idx = int_const_binop (MULT_EXPR, array_idx, elt_size, 0);
2148 /* Update the operands for the next round, or for folding. */
2149 op1 = int_const_binop (PLUS_EXPR,
2154 ptd_type = TREE_TYPE (res_type);
2155 /* If we want a pointer to void, reconstruct the reference from the
2156 array element type. A pointer to that can be trivially converted
2157 to void *. This happens as we fold (void *)(ptr p+ off). */
2158 if (VOID_TYPE_P (ptd_type)
2159 && TREE_CODE (TREE_TYPE (op0)) == ARRAY_TYPE)
2160 ptd_type = TREE_TYPE (TREE_TYPE (op0));
2162 /* At which point we can try some of the same things as for indirects. */
2163 t = maybe_fold_offset_to_array_ref (op0, op1, ptd_type, true);
2165 t = maybe_fold_offset_to_component_ref (TREE_TYPE (op0), op0, op1,
2168 t = build1 (ADDR_EXPR, res_type, t);
2173 /* For passing state through walk_tree into fold_stmt_r and its
2176 struct fold_stmt_r_data
2180 bool *inside_addr_expr_p;
2183 /* Subroutine of fold_stmt called via walk_tree. We perform several
2184 simplifications of EXPR_P, mostly having to do with pointer arithmetic. */
2187 fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data)
2189 struct walk_stmt_info *wi = (struct walk_stmt_info *) data;
2190 struct fold_stmt_r_data *fold_stmt_r_data;
2191 bool *inside_addr_expr_p;
2193 tree expr = *expr_p, t;
2194 bool volatile_p = TREE_THIS_VOLATILE (expr);
2196 fold_stmt_r_data = (struct fold_stmt_r_data *) wi->info;
2197 inside_addr_expr_p = fold_stmt_r_data->inside_addr_expr_p;
2198 changed_p = fold_stmt_r_data->changed_p;
2200 /* ??? It'd be nice if walk_tree had a pre-order option. */
2201 switch (TREE_CODE (expr))
2204 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2209 t = maybe_fold_stmt_indirect (expr, TREE_OPERAND (expr, 0),
2212 && TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR)
2213 /* If we had a good reason for propagating the address here,
2214 make sure we end up with valid gimple. See PR34989. */
2215 t = TREE_OPERAND (TREE_OPERAND (expr, 0), 0);
2219 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2224 if (POINTER_TYPE_P (TREE_TYPE (expr))
2225 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0)))
2226 && (t = maybe_fold_offset_to_reference
2227 (TREE_OPERAND (expr, 0),
2229 TREE_TYPE (TREE_TYPE (expr)))))
2231 tree ptr_type = build_pointer_type (TREE_TYPE (t));
2232 if (!useless_type_conversion_p (TREE_TYPE (expr), ptr_type))
2234 t = build_fold_addr_expr_with_type (t, ptr_type);
2238 /* ??? Could handle more ARRAY_REFs here, as a variant of INDIRECT_REF.
2239 We'd only want to bother decomposing an existing ARRAY_REF if
2240 the base array is found to have another offset contained within.
2241 Otherwise we'd be wasting time. */
2243 /* If we are not processing expressions found within an
2244 ADDR_EXPR, then we can fold constant array references. */
2245 if (!*inside_addr_expr_p)
2246 t = fold_read_from_constant_string (expr);
2252 *inside_addr_expr_p = true;
2253 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2254 *inside_addr_expr_p = false;
2259 /* Make sure the value is properly considered constant, and so gets
2260 propagated as expected. */
2262 recompute_tree_invariant_for_addr_expr (expr);
2266 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2271 /* Make sure the FIELD_DECL is actually a field in the type on the lhs.
2272 We've already checked that the records are compatible, so we should
2273 come up with a set of compatible fields. */
2275 tree expr_record = TREE_TYPE (TREE_OPERAND (expr, 0));
2276 tree expr_field = TREE_OPERAND (expr, 1);
2278 if (DECL_FIELD_CONTEXT (expr_field) != TYPE_MAIN_VARIANT (expr_record))
2280 expr_field = find_compatible_field (expr_record, expr_field);
2281 TREE_OPERAND (expr, 1) = expr_field;
2286 case TARGET_MEM_REF:
2287 t = maybe_fold_tmr (expr);
2290 case POINTER_PLUS_EXPR:
2291 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL);
2294 t = walk_tree (&TREE_OPERAND (expr, 1), fold_stmt_r, data, NULL);
2299 t = maybe_fold_stmt_addition (TREE_TYPE (expr),
2300 TREE_OPERAND (expr, 0),
2301 TREE_OPERAND (expr, 1));
2305 if (COMPARISON_CLASS_P (TREE_OPERAND (expr, 0)))
2307 tree op0 = TREE_OPERAND (expr, 0);
2311 fold_defer_overflow_warnings ();
2312 tem = fold_binary (TREE_CODE (op0), TREE_TYPE (op0),
2313 TREE_OPERAND (op0, 0),
2314 TREE_OPERAND (op0, 1));
2315 /* This is actually a conditional expression, not a GIMPLE
2316 conditional statement, however, the valid_gimple_rhs_p
2317 test still applies. */
2318 set = tem && is_gimple_condexpr (tem) && valid_gimple_rhs_p (tem);
2319 fold_undefer_overflow_warnings (set, fold_stmt_r_data->stmt, 0);
2322 COND_EXPR_COND (expr) = tem;
2335 /* Preserve volatileness of the original expression. */
2336 TREE_THIS_VOLATILE (t) = volatile_p;
2344 /* Return the string length, maximum string length or maximum value of
2346 If ARG is an SSA name variable, follow its use-def chains. If LENGTH
2347 is not NULL and, for TYPE == 0, its value is not equal to the length
2348 we determine or if we are unable to determine the length or value,
2349 return false. VISITED is a bitmap of visited variables.
2350 TYPE is 0 if string length should be returned, 1 for maximum string
2351 length and 2 for maximum value ARG can have. */
2354 get_maxval_strlen (tree arg, tree *length, bitmap visited, int type)
2359 if (TREE_CODE (arg) != SSA_NAME)
2361 if (TREE_CODE (arg) == COND_EXPR)
2362 return get_maxval_strlen (COND_EXPR_THEN (arg), length, visited, type)
2363 && get_maxval_strlen (COND_EXPR_ELSE (arg), length, visited, type);
2364 /* We can end up with &(*iftmp_1)[0] here as well, so handle it. */
2365 else if (TREE_CODE (arg) == ADDR_EXPR
2366 && TREE_CODE (TREE_OPERAND (arg, 0)) == ARRAY_REF
2367 && integer_zerop (TREE_OPERAND (TREE_OPERAND (arg, 0), 1)))
2369 tree aop0 = TREE_OPERAND (TREE_OPERAND (arg, 0), 0);
2370 if (TREE_CODE (aop0) == INDIRECT_REF
2371 && TREE_CODE (TREE_OPERAND (aop0, 0)) == SSA_NAME)
2372 return get_maxval_strlen (TREE_OPERAND (aop0, 0),
2373 length, visited, type);
2379 if (TREE_CODE (val) != INTEGER_CST
2380 || tree_int_cst_sgn (val) < 0)
2384 val = c_strlen (arg, 1);
2392 if (TREE_CODE (*length) != INTEGER_CST
2393 || TREE_CODE (val) != INTEGER_CST)
2396 if (tree_int_cst_lt (*length, val))
2400 else if (simple_cst_equal (val, *length) != 1)
2408 /* If we were already here, break the infinite cycle. */
2409 if (bitmap_bit_p (visited, SSA_NAME_VERSION (arg)))
2411 bitmap_set_bit (visited, SSA_NAME_VERSION (arg));
2414 def_stmt = SSA_NAME_DEF_STMT (var);
2416 switch (gimple_code (def_stmt))
2419 /* The RHS of the statement defining VAR must either have a
2420 constant length or come from another SSA_NAME with a constant
2422 if (gimple_assign_single_p (def_stmt)
2423 || gimple_assign_unary_nop_p (def_stmt))
2425 tree rhs = gimple_assign_rhs1 (def_stmt);
2426 return get_maxval_strlen (rhs, length, visited, type);
2432 /* All the arguments of the PHI node must have the same constant
2436 for (i = 0; i < gimple_phi_num_args (def_stmt); i++)
2438 tree arg = gimple_phi_arg (def_stmt, i)->def;
2440 /* If this PHI has itself as an argument, we cannot
2441 determine the string length of this argument. However,
2442 if we can find a constant string length for the other
2443 PHI args then we can still be sure that this is a
2444 constant string length. So be optimistic and just
2445 continue with the next argument. */
2446 if (arg == gimple_phi_result (def_stmt))
2449 if (!get_maxval_strlen (arg, length, visited, type))
2461 /* Fold builtin call in statement STMT. Returns a simplified tree.
2462 We may return a non-constant expression, including another call
2463 to a different function and with different arguments, e.g.,
2464 substituting memcpy for strcpy when the string length is known.
2465 Note that some builtins expand into inline code that may not
2466 be valid in GIMPLE. Callers must take care. */
2469 ccp_fold_builtin (gimple stmt)
2471 tree result, val[3];
2473 int arg_mask, i, type;
2478 gcc_assert (is_gimple_call (stmt));
2480 ignore = (gimple_call_lhs (stmt) == NULL);
2482 /* First try the generic builtin folder. If that succeeds, return the
2484 result = fold_call_stmt (stmt, ignore);
2488 STRIP_NOPS (result);
2492 /* Ignore MD builtins. */
2493 callee = gimple_call_fndecl (stmt);
2494 if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_MD)
2497 /* If the builtin could not be folded, and it has no argument list,
2499 nargs = gimple_call_num_args (stmt);
2503 /* Limit the work only for builtins we know how to simplify. */
2504 switch (DECL_FUNCTION_CODE (callee))
2506 case BUILT_IN_STRLEN:
2507 case BUILT_IN_FPUTS:
2508 case BUILT_IN_FPUTS_UNLOCKED:
2512 case BUILT_IN_STRCPY:
2513 case BUILT_IN_STRNCPY:
2517 case BUILT_IN_MEMCPY_CHK:
2518 case BUILT_IN_MEMPCPY_CHK:
2519 case BUILT_IN_MEMMOVE_CHK:
2520 case BUILT_IN_MEMSET_CHK:
2521 case BUILT_IN_STRNCPY_CHK:
2525 case BUILT_IN_STRCPY_CHK:
2526 case BUILT_IN_STPCPY_CHK:
2530 case BUILT_IN_SNPRINTF_CHK:
2531 case BUILT_IN_VSNPRINTF_CHK:
2539 /* Try to use the dataflow information gathered by the CCP process. */
2540 visited = BITMAP_ALLOC (NULL);
2542 memset (val, 0, sizeof (val));
2543 for (i = 0; i < nargs; i++)
2545 if ((arg_mask >> i) & 1)
2547 a = gimple_call_arg (stmt, i);
2548 bitmap_clear (visited);
2549 if (!get_maxval_strlen (a, &val[i], visited, type))
2554 BITMAP_FREE (visited);
2557 switch (DECL_FUNCTION_CODE (callee))
2559 case BUILT_IN_STRLEN:
2563 fold_convert (TREE_TYPE (gimple_call_lhs (stmt)), val[0]);
2565 /* If the result is not a valid gimple value, or not a cast
2566 of a valid gimple value, then we can not use the result. */
2567 if (is_gimple_val (new_val)
2568 || (is_gimple_cast (new_val)
2569 && is_gimple_val (TREE_OPERAND (new_val, 0))))
2574 case BUILT_IN_STRCPY:
2575 if (val[1] && is_gimple_val (val[1]) && nargs == 2)
2576 result = fold_builtin_strcpy (callee,
2577 gimple_call_arg (stmt, 0),
2578 gimple_call_arg (stmt, 1),
2582 case BUILT_IN_STRNCPY:
2583 if (val[1] && is_gimple_val (val[1]) && nargs == 3)
2584 result = fold_builtin_strncpy (callee,
2585 gimple_call_arg (stmt, 0),
2586 gimple_call_arg (stmt, 1),
2587 gimple_call_arg (stmt, 2),
2591 case BUILT_IN_FPUTS:
2592 result = fold_builtin_fputs (gimple_call_arg (stmt, 0),
2593 gimple_call_arg (stmt, 1),
2594 ignore, false, val[0]);
2597 case BUILT_IN_FPUTS_UNLOCKED:
2598 result = fold_builtin_fputs (gimple_call_arg (stmt, 0),
2599 gimple_call_arg (stmt, 1),
2600 ignore, true, val[0]);
2603 case BUILT_IN_MEMCPY_CHK:
2604 case BUILT_IN_MEMPCPY_CHK:
2605 case BUILT_IN_MEMMOVE_CHK:
2606 case BUILT_IN_MEMSET_CHK:
2607 if (val[2] && is_gimple_val (val[2]))
2608 result = fold_builtin_memory_chk (callee,
2609 gimple_call_arg (stmt, 0),
2610 gimple_call_arg (stmt, 1),
2611 gimple_call_arg (stmt, 2),
2612 gimple_call_arg (stmt, 3),
2614 DECL_FUNCTION_CODE (callee));
2617 case BUILT_IN_STRCPY_CHK:
2618 case BUILT_IN_STPCPY_CHK:
2619 if (val[1] && is_gimple_val (val[1]))
2620 result = fold_builtin_stxcpy_chk (callee,
2621 gimple_call_arg (stmt, 0),
2622 gimple_call_arg (stmt, 1),
2623 gimple_call_arg (stmt, 2),
2625 DECL_FUNCTION_CODE (callee));
2628 case BUILT_IN_STRNCPY_CHK:
2629 if (val[2] && is_gimple_val (val[2]))
2630 result = fold_builtin_strncpy_chk (gimple_call_arg (stmt, 0),
2631 gimple_call_arg (stmt, 1),
2632 gimple_call_arg (stmt, 2),
2633 gimple_call_arg (stmt, 3),
2637 case BUILT_IN_SNPRINTF_CHK:
2638 case BUILT_IN_VSNPRINTF_CHK:
2639 if (val[1] && is_gimple_val (val[1]))
2640 result = gimple_fold_builtin_snprintf_chk (stmt, val[1],
2641 DECL_FUNCTION_CODE (callee));
2648 if (result && ignore)
2649 result = fold_ignored_result (result);
2653 /* Attempt to fold an assignment statement pointed-to by SI. Returns a
2654 replacement rhs for the statement or NULL_TREE if no simplification
2655 could be made. It is assumed that the operands have been previously
2659 fold_gimple_assign (gimple_stmt_iterator *si)
2661 gimple stmt = gsi_stmt (*si);
2662 enum tree_code subcode = gimple_assign_rhs_code (stmt);
2666 switch (get_gimple_rhs_class (subcode))
2668 case GIMPLE_SINGLE_RHS:
2670 tree rhs = gimple_assign_rhs1 (stmt);
2672 /* Try to fold a conditional expression. */
2673 if (TREE_CODE (rhs) == COND_EXPR)
2675 tree temp = fold (COND_EXPR_COND (rhs));
2676 if (temp != COND_EXPR_COND (rhs))
2677 result = fold_build3 (COND_EXPR, TREE_TYPE (rhs), temp,
2678 COND_EXPR_THEN (rhs), COND_EXPR_ELSE (rhs));
2681 /* If we couldn't fold the RHS, hand over to the generic
2683 if (result == NULL_TREE)
2684 result = fold (rhs);
2686 /* Strip away useless type conversions. Both the NON_LVALUE_EXPR
2687 that may have been added by fold, and "useless" type
2688 conversions that might now be apparent due to propagation. */
2689 STRIP_USELESS_TYPE_CONVERSION (result);
2691 if (result != rhs && valid_gimple_rhs_p (result))
2694 /* It is possible that fold_stmt_r simplified the RHS.
2695 Make sure that the subcode of this statement still
2696 reflects the principal operator of the rhs operand. */
2701 case GIMPLE_UNARY_RHS:
2702 result = fold_unary (subcode,
2703 gimple_expr_type (stmt),
2704 gimple_assign_rhs1 (stmt));
2708 STRIP_USELESS_TYPE_CONVERSION (result);
2709 if (valid_gimple_rhs_p (result))
2712 else if ((gimple_assign_rhs_code (stmt) == NOP_EXPR
2713 || gimple_assign_rhs_code (stmt) == CONVERT_EXPR)
2714 && POINTER_TYPE_P (gimple_expr_type (stmt))
2715 && POINTER_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (stmt))))
2717 tree type = gimple_expr_type (stmt);
2718 tree t = maybe_fold_offset_to_reference (gimple_assign_rhs1 (stmt),
2723 tree ptr_type = build_pointer_type (TREE_TYPE (t));
2724 if (useless_type_conversion_p (type, ptr_type))
2725 return build_fold_addr_expr_with_type (t, ptr_type);
2730 case GIMPLE_BINARY_RHS:
2731 /* Try to fold pointer addition. */
2732 if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR)
2733 result = maybe_fold_stmt_addition (
2734 TREE_TYPE (gimple_assign_lhs (stmt)),
2735 gimple_assign_rhs1 (stmt),
2736 gimple_assign_rhs2 (stmt));
2739 result = fold_binary (subcode,
2740 TREE_TYPE (gimple_assign_lhs (stmt)),
2741 gimple_assign_rhs1 (stmt),
2742 gimple_assign_rhs2 (stmt));
2746 STRIP_USELESS_TYPE_CONVERSION (result);
2747 if (valid_gimple_rhs_p (result))
2752 case GIMPLE_INVALID_RHS:
2759 /* Attempt to fold a conditional statement. Return true if any changes were
2760 made. We only attempt to fold the condition expression, and do not perform
2761 any transformation that would require alteration of the cfg. It is
2762 assumed that the operands have been previously folded. */
2765 fold_gimple_cond (gimple stmt)
2767 tree result = fold_binary (gimple_cond_code (stmt),
2769 gimple_cond_lhs (stmt),
2770 gimple_cond_rhs (stmt));
2774 STRIP_USELESS_TYPE_CONVERSION (result);
2775 if (is_gimple_condexpr (result) && valid_gimple_rhs_p (result))
2777 gimple_cond_set_condition_from_tree (stmt, result);
2786 /* Attempt to fold a call statement referenced by the statement iterator GSI.
2787 The statement may be replaced by another statement, e.g., if the call
2788 simplifies to a constant value. Return true if any changes were made.
2789 It is assumed that the operands have been previously folded. */
2792 fold_gimple_call (gimple_stmt_iterator *gsi)
2794 gimple stmt = gsi_stmt (*gsi);
2796 tree callee = gimple_call_fndecl (stmt);
2798 /* Check for builtins that CCP can handle using information not
2799 available in the generic fold routines. */
2800 if (callee && DECL_BUILT_IN (callee))
2802 tree result = ccp_fold_builtin (stmt);
2805 return update_call_from_tree (gsi, result);
2809 /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve
2810 here are when we've propagated the address of a decl into the
2812 /* ??? Should perhaps do this in fold proper. However, doing it
2813 there requires that we create a new CALL_EXPR, and that requires
2814 copying EH region info to the new node. Easier to just do it
2815 here where we can just smash the call operand. */
2816 /* ??? Is there a good reason not to do this in fold_stmt_inplace? */
2817 callee = gimple_call_fn (stmt);
2818 if (TREE_CODE (callee) == OBJ_TYPE_REF
2819 && lang_hooks.fold_obj_type_ref
2820 && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee)) == ADDR_EXPR
2821 && DECL_P (TREE_OPERAND
2822 (OBJ_TYPE_REF_OBJECT (callee), 0)))
2826 /* ??? Caution: Broken ADDR_EXPR semantics means that
2827 looking at the type of the operand of the addr_expr
2828 can yield an array type. See silly exception in
2829 check_pointer_types_r. */
2830 t = TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee)));
2831 t = lang_hooks.fold_obj_type_ref (callee, t);
2834 gimple_call_set_fn (stmt, t);
2843 /* Fold the statement pointed to by GSI. In some cases, this function may
2844 replace the whole statement with a new one. Returns true iff folding
2845 makes any changes. */
2848 fold_stmt (gimple_stmt_iterator *gsi)
2851 struct fold_stmt_r_data fold_stmt_r_data;
2852 struct walk_stmt_info wi;
2854 bool changed = false;
2855 bool inside_addr_expr = false;
2857 gimple stmt = gsi_stmt (*gsi);
2859 fold_stmt_r_data.stmt = stmt;
2860 fold_stmt_r_data.changed_p = &changed;
2861 fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr;
2863 memset (&wi, 0, sizeof (wi));
2864 wi.info = &fold_stmt_r_data;
2866 /* Fold the individual operands.
2867 For example, fold instances of *&VAR into VAR, etc. */
2868 res = walk_gimple_op (stmt, fold_stmt_r, &wi);
2871 /* Fold the main computation performed by the statement. */
2872 switch (gimple_code (stmt))
2876 tree new_rhs = fold_gimple_assign (gsi);
2877 if (new_rhs != NULL_TREE)
2879 gimple_assign_set_rhs_from_tree (gsi, new_rhs);
2882 stmt = gsi_stmt (*gsi);
2886 changed |= fold_gimple_cond (stmt);
2889 /* The entire statement may be replaced in this case. */
2890 changed |= fold_gimple_call (gsi);
2901 /* Perform the minimal folding on statement STMT. Only operations like
2902 *&x created by constant propagation are handled. The statement cannot
2903 be replaced with a new one. Return true if the statement was
2904 changed, false otherwise. */
2907 fold_stmt_inplace (gimple stmt)
2910 struct fold_stmt_r_data fold_stmt_r_data;
2911 struct walk_stmt_info wi;
2912 gimple_stmt_iterator si;
2914 bool changed = false;
2915 bool inside_addr_expr = false;
2917 fold_stmt_r_data.stmt = stmt;
2918 fold_stmt_r_data.changed_p = &changed;
2919 fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr;
2921 memset (&wi, 0, sizeof (wi));
2922 wi.info = &fold_stmt_r_data;
2924 /* Fold the individual operands.
2925 For example, fold instances of *&VAR into VAR, etc.
2927 It appears that, at one time, maybe_fold_stmt_indirect
2928 would cause the walk to return non-null in order to
2929 signal that the entire statement should be replaced with
2930 a call to _builtin_trap. This functionality is currently
2931 disabled, as noted in a FIXME, and cannot be supported here. */
2932 res = walk_gimple_op (stmt, fold_stmt_r, &wi);
2935 /* Fold the main computation performed by the statement. */
2936 switch (gimple_code (stmt))
2940 unsigned old_num_ops;
2942 old_num_ops = gimple_num_ops (stmt);
2943 si = gsi_for_stmt (stmt);
2944 new_rhs = fold_gimple_assign (&si);
2945 if (new_rhs != NULL_TREE
2946 && get_gimple_rhs_num_ops (TREE_CODE (new_rhs)) < old_num_ops)
2948 gimple_assign_set_rhs_from_tree (&si, new_rhs);
2951 gcc_assert (gsi_stmt (si) == stmt);
2955 changed |= fold_gimple_cond (stmt);
2965 /* Try to optimize out __builtin_stack_restore. Optimize it out
2966 if there is another __builtin_stack_restore in the same basic
2967 block and no calls or ASM_EXPRs are in between, or if this block's
2968 only outgoing edge is to EXIT_BLOCK and there are no calls or
2969 ASM_EXPRs after this __builtin_stack_restore. */
2972 optimize_stack_restore (gimple_stmt_iterator i)
2975 gimple stmt, stack_save;
2976 gimple_stmt_iterator stack_save_gsi;
2978 basic_block bb = gsi_bb (i);
2979 gimple call = gsi_stmt (i);
2981 if (gimple_code (call) != GIMPLE_CALL
2982 || gimple_call_num_args (call) != 1
2983 || TREE_CODE (gimple_call_arg (call, 0)) != SSA_NAME
2984 || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call, 0))))
2987 for (gsi_next (&i); !gsi_end_p (i); gsi_next (&i))
2989 stmt = gsi_stmt (i);
2990 if (gimple_code (stmt) == GIMPLE_ASM)
2992 if (gimple_code (stmt) != GIMPLE_CALL)
2995 callee = gimple_call_fndecl (stmt);
2996 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
2999 if (DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_RESTORE)
3004 && (! single_succ_p (bb)
3005 || single_succ_edge (bb)->dest != EXIT_BLOCK_PTR))
3008 stack_save = SSA_NAME_DEF_STMT (gimple_call_arg (call, 0));
3009 if (gimple_code (stack_save) != GIMPLE_CALL
3010 || gimple_call_lhs (stack_save) != gimple_call_arg (call, 0)
3011 || stmt_could_throw_p (stack_save)
3012 || !has_single_use (gimple_call_arg (call, 0)))
3015 callee = gimple_call_fndecl (stack_save);
3017 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
3018 || DECL_FUNCTION_CODE (callee) != BUILT_IN_STACK_SAVE
3019 || gimple_call_num_args (stack_save) != 0)
3022 stack_save_gsi = gsi_for_stmt (stack_save);
3023 push_stmt_changes (gsi_stmt_ptr (&stack_save_gsi));
3024 rhs = build_int_cst (TREE_TYPE (gimple_call_arg (call, 0)), 0);
3025 if (!update_call_from_tree (&stack_save_gsi, rhs))
3027 discard_stmt_changes (gsi_stmt_ptr (&stack_save_gsi));
3030 pop_stmt_changes (gsi_stmt_ptr (&stack_save_gsi));
3032 /* No effect, so the statement will be deleted. */
3033 return integer_zero_node;
3036 /* If va_list type is a simple pointer and nothing special is needed,
3037 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
3038 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
3039 pointer assignment. */
3042 optimize_stdarg_builtin (gimple call)
3044 tree callee, lhs, rhs, cfun_va_list;
3045 bool va_list_simple_ptr;
3047 if (gimple_code (call) != GIMPLE_CALL)
3050 callee = gimple_call_fndecl (call);
3052 cfun_va_list = targetm.fn_abi_va_list (callee);
3053 va_list_simple_ptr = POINTER_TYPE_P (cfun_va_list)
3054 && (TREE_TYPE (cfun_va_list) == void_type_node
3055 || TREE_TYPE (cfun_va_list) == char_type_node);
3057 switch (DECL_FUNCTION_CODE (callee))
3059 case BUILT_IN_VA_START:
3060 if (!va_list_simple_ptr
3061 || targetm.expand_builtin_va_start != NULL
3062 || built_in_decls[BUILT_IN_NEXT_ARG] == NULL)
3065 if (gimple_call_num_args (call) != 2)
3068 lhs = gimple_call_arg (call, 0);
3069 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
3070 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
3071 != TYPE_MAIN_VARIANT (cfun_va_list))
3074 lhs = build_fold_indirect_ref (lhs);
3075 rhs = build_call_expr (built_in_decls[BUILT_IN_NEXT_ARG],
3076 1, integer_zero_node);
3077 rhs = fold_convert (TREE_TYPE (lhs), rhs);
3078 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
3080 case BUILT_IN_VA_COPY:
3081 if (!va_list_simple_ptr)
3084 if (gimple_call_num_args (call) != 2)
3087 lhs = gimple_call_arg (call, 0);
3088 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
3089 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
3090 != TYPE_MAIN_VARIANT (cfun_va_list))
3093 lhs = build_fold_indirect_ref (lhs);
3094 rhs = gimple_call_arg (call, 1);
3095 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs))
3096 != TYPE_MAIN_VARIANT (cfun_va_list))
3099 rhs = fold_convert (TREE_TYPE (lhs), rhs);
3100 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
3102 case BUILT_IN_VA_END:
3103 /* No effect, so the statement will be deleted. */
3104 return integer_zero_node;
3111 /* Convert EXPR into a GIMPLE value suitable for substitution on the
3112 RHS of an assignment. Insert the necessary statements before
3113 iterator *SI_P. The statement at *SI_P, which must be a GIMPLE_CALL
3114 is replaced. If the call is expected to produces a result, then it
3115 is replaced by an assignment of the new RHS to the result variable.
3116 If the result is to be ignored, then the call is replaced by a
3120 gimplify_and_update_call_from_tree (gimple_stmt_iterator *si_p, tree expr)
3123 tree tmp = NULL_TREE; /* Silence warning. */
3124 gimple stmt, new_stmt;
3125 gimple_stmt_iterator i;
3126 gimple_seq stmts = gimple_seq_alloc();
3127 struct gimplify_ctx gctx;
3129 stmt = gsi_stmt (*si_p);
3131 gcc_assert (is_gimple_call (stmt));
3133 lhs = gimple_call_lhs (stmt);
3135 push_gimplify_context (&gctx);
3137 if (lhs == NULL_TREE)
3138 gimplify_and_add (expr, &stmts);
3140 tmp = get_initialized_tmp_var (expr, &stmts, NULL);
3142 pop_gimplify_context (NULL);
3144 if (gimple_has_location (stmt))
3145 annotate_all_with_location (stmts, gimple_location (stmt));
3147 /* The replacement can expose previously unreferenced variables. */
3148 for (i = gsi_start (stmts); !gsi_end_p (i); gsi_next (&i))
3150 new_stmt = gsi_stmt (i);
3151 find_new_referenced_vars (new_stmt);
3152 gsi_insert_before (si_p, new_stmt, GSI_NEW_STMT);
3153 mark_symbols_for_renaming (new_stmt);
3157 if (lhs == NULL_TREE)
3158 new_stmt = gimple_build_nop ();
3161 new_stmt = gimple_build_assign (lhs, tmp);
3162 copy_virtual_operands (new_stmt, stmt);
3163 move_ssa_defining_stmt_for_defs (new_stmt, stmt);
3166 gimple_set_location (new_stmt, gimple_location (stmt));
3167 gsi_replace (si_p, new_stmt, false);
3170 /* A simple pass that attempts to fold all builtin functions. This pass
3171 is run after we've propagated as many constants as we can. */
3174 execute_fold_all_builtins (void)
3176 bool cfg_changed = false;
3178 unsigned int todoflags = 0;
3182 gimple_stmt_iterator i;
3183 for (i = gsi_start_bb (bb); !gsi_end_p (i); )
3185 gimple stmt, old_stmt;
3186 tree callee, result;
3187 enum built_in_function fcode;
3189 stmt = gsi_stmt (i);
3191 if (gimple_code (stmt) != GIMPLE_CALL)
3196 callee = gimple_call_fndecl (stmt);
3197 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
3202 fcode = DECL_FUNCTION_CODE (callee);
3204 result = ccp_fold_builtin (stmt);
3207 gimple_remove_stmt_histograms (cfun, stmt);
3210 switch (DECL_FUNCTION_CODE (callee))
3212 case BUILT_IN_CONSTANT_P:
3213 /* Resolve __builtin_constant_p. If it hasn't been
3214 folded to integer_one_node by now, it's fairly
3215 certain that the value simply isn't constant. */
3216 result = integer_zero_node;
3219 case BUILT_IN_STACK_RESTORE:
3220 result = optimize_stack_restore (i);
3226 case BUILT_IN_VA_START:
3227 case BUILT_IN_VA_END:
3228 case BUILT_IN_VA_COPY:
3229 /* These shouldn't be folded before pass_stdarg. */
3230 result = optimize_stdarg_builtin (stmt);
3240 if (dump_file && (dump_flags & TDF_DETAILS))
3242 fprintf (dump_file, "Simplified\n ");
3243 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
3247 push_stmt_changes (gsi_stmt_ptr (&i));
3249 if (!update_call_from_tree (&i, result))
3251 gimplify_and_update_call_from_tree (&i, result);
3252 todoflags |= TODO_rebuild_alias;
3255 stmt = gsi_stmt (i);
3256 pop_stmt_changes (gsi_stmt_ptr (&i));
3258 if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt)
3259 && gimple_purge_dead_eh_edges (bb))
3262 if (dump_file && (dump_flags & TDF_DETAILS))
3264 fprintf (dump_file, "to\n ");
3265 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
3266 fprintf (dump_file, "\n");
3269 /* Retry the same statement if it changed into another
3270 builtin, there might be new opportunities now. */
3271 if (gimple_code (stmt) != GIMPLE_CALL)
3276 callee = gimple_call_fndecl (stmt);
3278 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
3279 || DECL_FUNCTION_CODE (callee) == fcode)
3284 /* Delete unreachable blocks. */
3286 todoflags |= TODO_cleanup_cfg;
3292 struct gimple_opt_pass pass_fold_builtins =
3298 execute_fold_all_builtins, /* execute */
3301 0, /* static_pass_number */
3303 PROP_cfg | PROP_ssa, /* properties_required */
3304 0, /* properties_provided */
3305 0, /* properties_destroyed */
3306 0, /* todo_flags_start */
3309 | TODO_update_ssa /* todo_flags_finish */