1 /* Conditional constant propagation pass for the GNU compiler.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
3 2010 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.
104 Constant propagation with conditional branches,
105 Wegman and Zadeck, ACM TOPLAS 13(2):181-210.
107 Building an Optimizing Compiler,
108 Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9.
110 Advanced Compiler Design and Implementation,
111 Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */
115 #include "coretypes.h"
120 #include "basic-block.h"
122 #include "function.h"
123 #include "tree-pretty-print.h"
124 #include "gimple-pretty-print.h"
126 #include "tree-dump.h"
127 #include "tree-flow.h"
128 #include "tree-pass.h"
129 #include "tree-ssa-propagate.h"
130 #include "value-prof.h"
131 #include "langhooks.h"
133 #include "diagnostic-core.h"
138 /* Possible lattice values. */
147 struct prop_value_d {
149 ccp_lattice_t lattice_val;
151 /* Propagated value. */
154 /* Mask that applies to the propagated value during CCP. For
155 X with a CONSTANT lattice value X & ~mask == value & ~mask. */
159 typedef struct prop_value_d prop_value_t;
161 /* Array of propagated constant values. After propagation,
162 CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If
163 the constant is held in an SSA name representing a memory store
164 (i.e., a VDEF), CONST_VAL[I].MEM_REF will contain the actual
165 memory reference used to store (i.e., the LHS of the assignment
167 static prop_value_t *const_val;
169 static void canonicalize_float_value (prop_value_t *);
170 static bool ccp_fold_stmt (gimple_stmt_iterator *);
172 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */
175 dump_lattice_value (FILE *outf, const char *prefix, prop_value_t val)
177 switch (val.lattice_val)
180 fprintf (outf, "%sUNINITIALIZED", prefix);
183 fprintf (outf, "%sUNDEFINED", prefix);
186 fprintf (outf, "%sVARYING", prefix);
189 fprintf (outf, "%sCONSTANT ", prefix);
190 if (TREE_CODE (val.value) != INTEGER_CST
191 || double_int_zero_p (val.mask))
192 print_generic_expr (outf, val.value, dump_flags);
195 double_int cval = double_int_and_not (tree_to_double_int (val.value),
197 fprintf (outf, "%sCONSTANT " HOST_WIDE_INT_PRINT_DOUBLE_HEX,
198 prefix, cval.high, cval.low);
199 fprintf (outf, " (" HOST_WIDE_INT_PRINT_DOUBLE_HEX ")",
200 val.mask.high, val.mask.low);
209 /* Print lattice value VAL to stderr. */
211 void debug_lattice_value (prop_value_t val);
214 debug_lattice_value (prop_value_t val)
216 dump_lattice_value (stderr, "", val);
217 fprintf (stderr, "\n");
221 /* Compute a default value for variable VAR and store it in the
222 CONST_VAL array. The following rules are used to get default
225 1- Global and static variables that are declared constant are
228 2- Any other value is considered UNDEFINED. This is useful when
229 considering PHI nodes. PHI arguments that are undefined do not
230 change the constant value of the PHI node, which allows for more
231 constants to be propagated.
233 3- Variables defined by statements other than assignments and PHI
234 nodes are considered VARYING.
236 4- Initial values of variables that are not GIMPLE registers are
237 considered VARYING. */
240 get_default_value (tree var)
242 tree sym = SSA_NAME_VAR (var);
243 prop_value_t val = { UNINITIALIZED, NULL_TREE, { 0, 0 } };
246 stmt = SSA_NAME_DEF_STMT (var);
248 if (gimple_nop_p (stmt))
250 /* Variables defined by an empty statement are those used
251 before being initialized. If VAR is a local variable, we
252 can assume initially that it is UNDEFINED, otherwise we must
253 consider it VARYING. */
254 if (is_gimple_reg (sym)
255 && TREE_CODE (sym) == VAR_DECL)
256 val.lattice_val = UNDEFINED;
259 val.lattice_val = VARYING;
260 val.mask = double_int_minus_one;
263 else if (is_gimple_assign (stmt)
264 /* Value-returning GIMPLE_CALL statements assign to
265 a variable, and are treated similarly to GIMPLE_ASSIGN. */
266 || (is_gimple_call (stmt)
267 && gimple_call_lhs (stmt) != NULL_TREE)
268 || gimple_code (stmt) == GIMPLE_PHI)
271 if (gimple_assign_single_p (stmt)
272 && DECL_P (gimple_assign_rhs1 (stmt))
273 && (cst = get_symbol_constant_value (gimple_assign_rhs1 (stmt))))
275 val.lattice_val = CONSTANT;
279 /* Any other variable defined by an assignment or a PHI node
280 is considered UNDEFINED. */
281 val.lattice_val = UNDEFINED;
285 /* Otherwise, VAR will never take on a constant value. */
286 val.lattice_val = VARYING;
287 val.mask = double_int_minus_one;
294 /* Get the constant value associated with variable VAR. */
296 static inline prop_value_t *
301 if (const_val == NULL)
304 val = &const_val[SSA_NAME_VERSION (var)];
305 if (val->lattice_val == UNINITIALIZED)
306 *val = get_default_value (var);
308 canonicalize_float_value (val);
313 /* Return the constant tree value associated with VAR. */
316 get_constant_value (tree var)
318 prop_value_t *val = get_value (var);
320 && val->lattice_val == CONSTANT
321 && (TREE_CODE (val->value) != INTEGER_CST
322 || double_int_zero_p (val->mask)))
327 /* Sets the value associated with VAR to VARYING. */
330 set_value_varying (tree var)
332 prop_value_t *val = &const_val[SSA_NAME_VERSION (var)];
334 val->lattice_val = VARYING;
335 val->value = NULL_TREE;
336 val->mask = double_int_minus_one;
339 /* For float types, modify the value of VAL to make ccp work correctly
340 for non-standard values (-0, NaN):
342 If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0.
343 If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED.
344 This is to fix the following problem (see PR 29921): Suppose we have
348 and we set value of y to NaN. This causes value of x to be set to NaN.
349 When we later determine that y is in fact VARYING, fold uses the fact
350 that HONOR_NANS is false, and we try to change the value of x to 0,
351 causing an ICE. With HONOR_NANS being false, the real appearance of
352 NaN would cause undefined behavior, though, so claiming that y (and x)
353 are UNDEFINED initially is correct. */
356 canonicalize_float_value (prop_value_t *val)
358 enum machine_mode mode;
362 if (val->lattice_val != CONSTANT
363 || TREE_CODE (val->value) != REAL_CST)
366 d = TREE_REAL_CST (val->value);
367 type = TREE_TYPE (val->value);
368 mode = TYPE_MODE (type);
370 if (!HONOR_SIGNED_ZEROS (mode)
371 && REAL_VALUE_MINUS_ZERO (d))
373 val->value = build_real (type, dconst0);
377 if (!HONOR_NANS (mode)
378 && REAL_VALUE_ISNAN (d))
380 val->lattice_val = UNDEFINED;
386 /* Return whether the lattice transition is valid. */
389 valid_lattice_transition (prop_value_t old_val, prop_value_t new_val)
391 /* Lattice transitions must always be monotonically increasing in
393 if (old_val.lattice_val < new_val.lattice_val)
396 if (old_val.lattice_val != new_val.lattice_val)
399 if (!old_val.value && !new_val.value)
402 /* Now both lattice values are CONSTANT. */
404 /* Allow transitioning from &x to &x & ~3. */
405 if (TREE_CODE (old_val.value) != INTEGER_CST
406 && TREE_CODE (new_val.value) == INTEGER_CST)
409 /* Bit-lattices have to agree in the still valid bits. */
410 if (TREE_CODE (old_val.value) == INTEGER_CST
411 && TREE_CODE (new_val.value) == INTEGER_CST)
412 return double_int_equal_p
413 (double_int_and_not (tree_to_double_int (old_val.value),
415 double_int_and_not (tree_to_double_int (new_val.value),
418 /* Otherwise constant values have to agree. */
419 return operand_equal_p (old_val.value, new_val.value, 0);
422 /* Set the value for variable VAR to NEW_VAL. Return true if the new
423 value is different from VAR's previous value. */
426 set_lattice_value (tree var, prop_value_t new_val)
428 /* We can deal with old UNINITIALIZED values just fine here. */
429 prop_value_t *old_val = &const_val[SSA_NAME_VERSION (var)];
431 canonicalize_float_value (&new_val);
433 /* We have to be careful to not go up the bitwise lattice
434 represented by the mask.
435 ??? This doesn't seem to be the best place to enforce this. */
436 if (new_val.lattice_val == CONSTANT
437 && old_val->lattice_val == CONSTANT
438 && TREE_CODE (new_val.value) == INTEGER_CST
439 && TREE_CODE (old_val->value) == INTEGER_CST)
442 diff = double_int_xor (tree_to_double_int (new_val.value),
443 tree_to_double_int (old_val->value));
444 new_val.mask = double_int_ior (new_val.mask,
445 double_int_ior (old_val->mask, diff));
448 gcc_assert (valid_lattice_transition (*old_val, new_val));
450 /* If *OLD_VAL and NEW_VAL are the same, return false to inform the
451 caller that this was a non-transition. */
452 if (old_val->lattice_val != new_val.lattice_val
453 || (new_val.lattice_val == CONSTANT
454 && TREE_CODE (new_val.value) == INTEGER_CST
455 && (TREE_CODE (old_val->value) != INTEGER_CST
456 || !double_int_equal_p (new_val.mask, old_val->mask))))
458 /* ??? We would like to delay creation of INTEGER_CSTs from
459 partially constants here. */
461 if (dump_file && (dump_flags & TDF_DETAILS))
463 dump_lattice_value (dump_file, "Lattice value changed to ", new_val);
464 fprintf (dump_file, ". Adding SSA edges to worklist.\n");
469 gcc_assert (new_val.lattice_val != UNINITIALIZED);
476 static prop_value_t get_value_for_expr (tree, bool);
477 static prop_value_t bit_value_binop (enum tree_code, tree, tree, tree);
478 static void bit_value_binop_1 (enum tree_code, tree, double_int *, double_int *,
479 tree, double_int, double_int,
480 tree, double_int, double_int);
482 /* Return a double_int that can be used for bitwise simplifications
486 value_to_double_int (prop_value_t val)
489 && TREE_CODE (val.value) == INTEGER_CST)
490 return tree_to_double_int (val.value);
492 return double_int_zero;
495 /* Return the value for the address expression EXPR based on alignment
499 get_value_from_alignment (tree expr)
502 HOST_WIDE_INT bitsize, bitpos;
504 enum machine_mode mode;
507 gcc_assert (TREE_CODE (expr) == ADDR_EXPR);
509 base = get_inner_reference (TREE_OPERAND (expr, 0),
510 &bitsize, &bitpos, &offset,
511 &mode, &align, &align, false);
512 if (TREE_CODE (base) == MISALIGNED_INDIRECT_REF)
513 val = get_value_for_expr (TREE_OPERAND (base, 0), true);
514 else if (TREE_CODE (base) == MEM_REF)
515 val = bit_value_binop (PLUS_EXPR, TREE_TYPE (expr),
516 TREE_OPERAND (base, 0), TREE_OPERAND (base, 1));
518 && ((align = get_object_alignment (base, BIGGEST_ALIGNMENT))
521 val.lattice_val = CONSTANT;
522 /* We assume pointers are zero-extended. */
523 val.mask = double_int_and_not
524 (double_int_mask (TYPE_PRECISION (TREE_TYPE (expr))),
525 uhwi_to_double_int (align / BITS_PER_UNIT - 1));
526 val.value = build_int_cst (TREE_TYPE (expr), 0);
530 val.lattice_val = VARYING;
531 val.mask = double_int_minus_one;
532 val.value = NULL_TREE;
536 double_int value, mask;
537 bit_value_binop_1 (PLUS_EXPR, TREE_TYPE (expr), &value, &mask,
538 TREE_TYPE (expr), value_to_double_int (val), val.mask,
540 shwi_to_double_int (bitpos / BITS_PER_UNIT),
542 val.lattice_val = double_int_minus_one_p (mask) ? VARYING : CONSTANT;
544 if (val.lattice_val == CONSTANT)
545 val.value = double_int_to_tree (TREE_TYPE (expr), value);
547 val.value = NULL_TREE;
549 /* ??? We should handle i * 4 and more complex expressions from
550 the offset, possibly by just expanding get_value_for_expr. */
551 if (offset != NULL_TREE)
553 double_int value, mask;
554 prop_value_t oval = get_value_for_expr (offset, true);
555 bit_value_binop_1 (PLUS_EXPR, TREE_TYPE (expr), &value, &mask,
556 TREE_TYPE (expr), value_to_double_int (val), val.mask,
557 TREE_TYPE (expr), value_to_double_int (oval),
560 if (double_int_minus_one_p (mask))
562 val.lattice_val = VARYING;
563 val.value = NULL_TREE;
567 val.lattice_val = CONSTANT;
568 val.value = double_int_to_tree (TREE_TYPE (expr), value);
575 /* Return the value for the tree operand EXPR. If FOR_BITS_P is true
576 return constant bits extracted from alignment information for
577 invariant addresses. */
580 get_value_for_expr (tree expr, bool for_bits_p)
584 if (TREE_CODE (expr) == SSA_NAME)
586 val = *get_value (expr);
588 && val.lattice_val == CONSTANT
589 && TREE_CODE (val.value) == ADDR_EXPR)
590 val = get_value_from_alignment (val.value);
592 else if (is_gimple_min_invariant (expr)
593 && (!for_bits_p || TREE_CODE (expr) != ADDR_EXPR))
595 val.lattice_val = CONSTANT;
597 val.mask = double_int_zero;
598 canonicalize_float_value (&val);
600 else if (TREE_CODE (expr) == ADDR_EXPR)
601 val = get_value_from_alignment (expr);
604 val.lattice_val = VARYING;
605 val.mask = double_int_minus_one;
606 val.value = NULL_TREE;
611 /* Return the likely CCP lattice value for STMT.
613 If STMT has no operands, then return CONSTANT.
615 Else if undefinedness of operands of STMT cause its value to be
616 undefined, then return UNDEFINED.
618 Else if any operands of STMT are constants, then return CONSTANT.
620 Else return VARYING. */
623 likely_value (gimple stmt)
625 bool has_constant_operand, has_undefined_operand, all_undefined_operands;
630 enum gimple_code code = gimple_code (stmt);
632 /* This function appears to be called only for assignments, calls,
633 conditionals, and switches, due to the logic in visit_stmt. */
634 gcc_assert (code == GIMPLE_ASSIGN
635 || code == GIMPLE_CALL
636 || code == GIMPLE_COND
637 || code == GIMPLE_SWITCH);
639 /* If the statement has volatile operands, it won't fold to a
641 if (gimple_has_volatile_ops (stmt))
644 /* Arrive here for more complex cases. */
645 has_constant_operand = false;
646 has_undefined_operand = false;
647 all_undefined_operands = true;
648 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE)
650 prop_value_t *val = get_value (use);
652 if (val->lattice_val == UNDEFINED)
653 has_undefined_operand = true;
655 all_undefined_operands = false;
657 if (val->lattice_val == CONSTANT)
658 has_constant_operand = true;
661 /* There may be constants in regular rhs operands. For calls we
662 have to ignore lhs, fndecl and static chain, otherwise only
664 for (i = (is_gimple_call (stmt) ? 2 : 0) + gimple_has_lhs (stmt);
665 i < gimple_num_ops (stmt); ++i)
667 tree op = gimple_op (stmt, i);
668 if (!op || TREE_CODE (op) == SSA_NAME)
670 if (is_gimple_min_invariant (op))
671 has_constant_operand = true;
674 if (has_constant_operand)
675 all_undefined_operands = false;
677 /* If the operation combines operands like COMPLEX_EXPR make sure to
678 not mark the result UNDEFINED if only one part of the result is
680 if (has_undefined_operand && all_undefined_operands)
682 else if (code == GIMPLE_ASSIGN && has_undefined_operand)
684 switch (gimple_assign_rhs_code (stmt))
686 /* Unary operators are handled with all_undefined_operands. */
689 case POINTER_PLUS_EXPR:
690 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected.
691 Not bitwise operators, one VARYING operand may specify the
692 result completely. Not logical operators for the same reason.
693 Not COMPLEX_EXPR as one VARYING operand makes the result partly
694 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because
695 the undefined operand may be promoted. */
702 /* If there was an UNDEFINED operand but the result may be not UNDEFINED
703 fall back to VARYING even if there were CONSTANT operands. */
704 if (has_undefined_operand)
707 /* We do not consider virtual operands here -- load from read-only
708 memory may have only VARYING virtual operands, but still be
710 if (has_constant_operand
711 || gimple_references_memory_p (stmt))
717 /* Returns true if STMT cannot be constant. */
720 surely_varying_stmt_p (gimple stmt)
722 /* If the statement has operands that we cannot handle, it cannot be
724 if (gimple_has_volatile_ops (stmt))
727 /* If it is a call and does not return a value or is not a
728 builtin and not an indirect call, it is varying. */
729 if (is_gimple_call (stmt))
732 if (!gimple_call_lhs (stmt)
733 || ((fndecl = gimple_call_fndecl (stmt)) != NULL_TREE
734 && !DECL_BUILT_IN (fndecl)))
738 /* Any other store operation is not interesting. */
739 else if (gimple_vdef (stmt))
742 /* Anything other than assignments and conditional jumps are not
743 interesting for CCP. */
744 if (gimple_code (stmt) != GIMPLE_ASSIGN
745 && gimple_code (stmt) != GIMPLE_COND
746 && gimple_code (stmt) != GIMPLE_SWITCH
747 && gimple_code (stmt) != GIMPLE_CALL)
753 /* Initialize local data structures for CCP. */
756 ccp_initialize (void)
760 const_val = XCNEWVEC (prop_value_t, num_ssa_names);
762 /* Initialize simulation flags for PHI nodes and statements. */
765 gimple_stmt_iterator i;
767 for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i))
769 gimple stmt = gsi_stmt (i);
772 /* If the statement is a control insn, then we do not
773 want to avoid simulating the statement once. Failure
774 to do so means that those edges will never get added. */
775 if (stmt_ends_bb_p (stmt))
778 is_varying = surely_varying_stmt_p (stmt);
785 /* If the statement will not produce a constant, mark
786 all its outputs VARYING. */
787 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
788 set_value_varying (def);
790 prop_set_simulate_again (stmt, !is_varying);
794 /* Now process PHI nodes. We never clear the simulate_again flag on
795 phi nodes, since we do not know which edges are executable yet,
796 except for phi nodes for virtual operands when we do not do store ccp. */
799 gimple_stmt_iterator i;
801 for (i = gsi_start_phis (bb); !gsi_end_p (i); gsi_next (&i))
803 gimple phi = gsi_stmt (i);
805 if (!is_gimple_reg (gimple_phi_result (phi)))
806 prop_set_simulate_again (phi, false);
808 prop_set_simulate_again (phi, true);
813 /* Debug count support. Reset the values of ssa names
814 VARYING when the total number ssa names analyzed is
815 beyond the debug count specified. */
821 for (i = 0; i < num_ssa_names; i++)
825 const_val[i].lattice_val = VARYING;
826 const_val[i].mask = double_int_minus_one;
827 const_val[i].value = NULL_TREE;
833 /* Do final substitution of propagated values, cleanup the flowgraph and
834 free allocated storage.
836 Return TRUE when something was optimized. */
841 bool something_changed;
844 /* Perform substitutions based on the known constant values. */
845 something_changed = substitute_and_fold (get_constant_value,
846 ccp_fold_stmt, true);
850 return something_changed;;
854 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
857 any M UNDEFINED = any
858 any M VARYING = VARYING
859 Ci M Cj = Ci if (i == j)
860 Ci M Cj = VARYING if (i != j)
864 ccp_lattice_meet (prop_value_t *val1, prop_value_t *val2)
866 if (val1->lattice_val == UNDEFINED)
868 /* UNDEFINED M any = any */
871 else if (val2->lattice_val == UNDEFINED)
873 /* any M UNDEFINED = any
874 Nothing to do. VAL1 already contains the value we want. */
877 else if (val1->lattice_val == VARYING
878 || val2->lattice_val == VARYING)
880 /* any M VARYING = VARYING. */
881 val1->lattice_val = VARYING;
882 val1->mask = double_int_minus_one;
883 val1->value = NULL_TREE;
885 else if (val1->lattice_val == CONSTANT
886 && val2->lattice_val == CONSTANT
887 && TREE_CODE (val1->value) == INTEGER_CST
888 && TREE_CODE (val2->value) == INTEGER_CST)
890 /* Ci M Cj = Ci if (i == j)
891 Ci M Cj = VARYING if (i != j)
893 For INTEGER_CSTs mask unequal bits. If no equal bits remain,
896 = double_int_ior (double_int_ior (val1->mask,
898 double_int_xor (tree_to_double_int (val1->value),
899 tree_to_double_int (val2->value)));
900 if (double_int_minus_one_p (val1->mask))
902 val1->lattice_val = VARYING;
903 val1->value = NULL_TREE;
906 else if (val1->lattice_val == CONSTANT
907 && val2->lattice_val == CONSTANT
908 && simple_cst_equal (val1->value, val2->value) == 1)
910 /* Ci M Cj = Ci if (i == j)
911 Ci M Cj = VARYING if (i != j)
913 VAL1 already contains the value we want for equivalent values. */
915 else if (val1->lattice_val == CONSTANT
916 && val2->lattice_val == CONSTANT
917 && (TREE_CODE (val1->value) == ADDR_EXPR
918 || TREE_CODE (val2->value) == ADDR_EXPR))
920 /* When not equal addresses are involved try meeting for
922 prop_value_t tem = *val2;
923 if (TREE_CODE (val1->value) == ADDR_EXPR)
924 *val1 = get_value_for_expr (val1->value, true);
925 if (TREE_CODE (val2->value) == ADDR_EXPR)
926 tem = get_value_for_expr (val2->value, true);
927 ccp_lattice_meet (val1, &tem);
931 /* Any other combination is VARYING. */
932 val1->lattice_val = VARYING;
933 val1->mask = double_int_minus_one;
934 val1->value = NULL_TREE;
939 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
940 lattice values to determine PHI_NODE's lattice value. The value of a
941 PHI node is determined calling ccp_lattice_meet with all the arguments
942 of the PHI node that are incoming via executable edges. */
944 static enum ssa_prop_result
945 ccp_visit_phi_node (gimple phi)
948 prop_value_t *old_val, new_val;
950 if (dump_file && (dump_flags & TDF_DETAILS))
952 fprintf (dump_file, "\nVisiting PHI node: ");
953 print_gimple_stmt (dump_file, phi, 0, dump_flags);
956 old_val = get_value (gimple_phi_result (phi));
957 switch (old_val->lattice_val)
960 return SSA_PROP_VARYING;
967 new_val.lattice_val = UNDEFINED;
968 new_val.value = NULL_TREE;
975 for (i = 0; i < gimple_phi_num_args (phi); i++)
977 /* Compute the meet operator over all the PHI arguments flowing
978 through executable edges. */
979 edge e = gimple_phi_arg_edge (phi, i);
981 if (dump_file && (dump_flags & TDF_DETAILS))
984 "\n Argument #%d (%d -> %d %sexecutable)\n",
985 i, e->src->index, e->dest->index,
986 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
989 /* If the incoming edge is executable, Compute the meet operator for
990 the existing value of the PHI node and the current PHI argument. */
991 if (e->flags & EDGE_EXECUTABLE)
993 tree arg = gimple_phi_arg (phi, i)->def;
994 prop_value_t arg_val = get_value_for_expr (arg, false);
996 ccp_lattice_meet (&new_val, &arg_val);
998 if (dump_file && (dump_flags & TDF_DETAILS))
1000 fprintf (dump_file, "\t");
1001 print_generic_expr (dump_file, arg, dump_flags);
1002 dump_lattice_value (dump_file, "\tValue: ", arg_val);
1003 fprintf (dump_file, "\n");
1006 if (new_val.lattice_val == VARYING)
1011 if (dump_file && (dump_flags & TDF_DETAILS))
1013 dump_lattice_value (dump_file, "\n PHI node value: ", new_val);
1014 fprintf (dump_file, "\n\n");
1017 /* Make the transition to the new value. */
1018 if (set_lattice_value (gimple_phi_result (phi), new_val))
1020 if (new_val.lattice_val == VARYING)
1021 return SSA_PROP_VARYING;
1023 return SSA_PROP_INTERESTING;
1026 return SSA_PROP_NOT_INTERESTING;
1029 /* Return the constant value for OP or OP otherwise. */
1032 valueize_op (tree op)
1034 if (TREE_CODE (op) == SSA_NAME)
1036 tree tem = get_constant_value (op);
1043 /* CCP specific front-end to the non-destructive constant folding
1046 Attempt to simplify the RHS of STMT knowing that one or more
1047 operands are constants.
1049 If simplification is possible, return the simplified RHS,
1050 otherwise return the original RHS or NULL_TREE. */
1053 ccp_fold (gimple stmt)
1055 location_t loc = gimple_location (stmt);
1056 switch (gimple_code (stmt))
1060 enum tree_code subcode = gimple_assign_rhs_code (stmt);
1062 switch (get_gimple_rhs_class (subcode))
1064 case GIMPLE_SINGLE_RHS:
1066 tree rhs = gimple_assign_rhs1 (stmt);
1067 enum tree_code_class kind = TREE_CODE_CLASS (subcode);
1069 if (TREE_CODE (rhs) == SSA_NAME)
1071 /* If the RHS is an SSA_NAME, return its known constant value,
1073 return get_constant_value (rhs);
1075 /* Handle propagating invariant addresses into address operations.
1076 The folding we do here matches that in tree-ssa-forwprop.c. */
1077 else if (TREE_CODE (rhs) == ADDR_EXPR)
1080 base = &TREE_OPERAND (rhs, 0);
1081 while (handled_component_p (*base))
1082 base = &TREE_OPERAND (*base, 0);
1083 if (TREE_CODE (*base) == MEM_REF
1084 && TREE_CODE (TREE_OPERAND (*base, 0)) == SSA_NAME)
1086 tree val = get_constant_value (TREE_OPERAND (*base, 0));
1088 && TREE_CODE (val) == ADDR_EXPR)
1090 tree ret, save = *base;
1092 new_base = fold_build2 (MEM_REF, TREE_TYPE (*base),
1094 TREE_OPERAND (*base, 1));
1095 /* We need to return a new tree, not modify the IL
1096 or share parts of it. So play some tricks to
1097 avoid manually building it. */
1099 ret = unshare_expr (rhs);
1100 recompute_tree_invariant_for_addr_expr (ret);
1106 else if (TREE_CODE (rhs) == CONSTRUCTOR
1107 && TREE_CODE (TREE_TYPE (rhs)) == VECTOR_TYPE
1108 && (CONSTRUCTOR_NELTS (rhs)
1109 == TYPE_VECTOR_SUBPARTS (TREE_TYPE (rhs))))
1115 FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (rhs), i, val)
1117 val = valueize_op (val);
1118 if (TREE_CODE (val) == INTEGER_CST
1119 || TREE_CODE (val) == REAL_CST
1120 || TREE_CODE (val) == FIXED_CST)
1121 list = tree_cons (NULL_TREE, val, list);
1126 return build_vector (TREE_TYPE (rhs), nreverse (list));
1129 if (kind == tcc_reference)
1131 if ((TREE_CODE (rhs) == VIEW_CONVERT_EXPR
1132 || TREE_CODE (rhs) == REALPART_EXPR
1133 || TREE_CODE (rhs) == IMAGPART_EXPR)
1134 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
1136 tree val = get_constant_value (TREE_OPERAND (rhs, 0));
1138 return fold_unary_loc (EXPR_LOCATION (rhs),
1140 TREE_TYPE (rhs), val);
1142 else if (TREE_CODE (rhs) == MEM_REF
1143 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
1145 tree val = get_constant_value (TREE_OPERAND (rhs, 0));
1147 && TREE_CODE (val) == ADDR_EXPR)
1149 tree tem = fold_build2 (MEM_REF, TREE_TYPE (rhs),
1151 TREE_OPERAND (rhs, 1));
1156 return fold_const_aggregate_ref (rhs);
1158 else if (kind == tcc_declaration)
1159 return get_symbol_constant_value (rhs);
1163 case GIMPLE_UNARY_RHS:
1165 /* Handle unary operators that can appear in GIMPLE form.
1166 Note that we know the single operand must be a constant,
1167 so this should almost always return a simplified RHS. */
1168 tree lhs = gimple_assign_lhs (stmt);
1169 tree op0 = valueize_op (gimple_assign_rhs1 (stmt));
1171 /* Conversions are useless for CCP purposes if they are
1172 value-preserving. Thus the restrictions that
1173 useless_type_conversion_p places for pointer type conversions
1174 do not apply here. Substitution later will only substitute to
1176 if (CONVERT_EXPR_CODE_P (subcode)
1177 && POINTER_TYPE_P (TREE_TYPE (lhs))
1178 && POINTER_TYPE_P (TREE_TYPE (op0)))
1181 /* Try to re-construct array references on-the-fly. */
1182 if (!useless_type_conversion_p (TREE_TYPE (lhs),
1184 && ((tem = maybe_fold_offset_to_address
1186 op0, integer_zero_node, TREE_TYPE (lhs)))
1193 fold_unary_ignore_overflow_loc (loc, subcode,
1194 gimple_expr_type (stmt), op0);
1197 case GIMPLE_BINARY_RHS:
1199 /* Handle binary operators that can appear in GIMPLE form. */
1200 tree op0 = valueize_op (gimple_assign_rhs1 (stmt));
1201 tree op1 = valueize_op (gimple_assign_rhs2 (stmt));
1203 /* Translate &x + CST into an invariant form suitable for
1204 further propagation. */
1205 if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR
1206 && TREE_CODE (op0) == ADDR_EXPR
1207 && TREE_CODE (op1) == INTEGER_CST)
1209 tree off = fold_convert (ptr_type_node, op1);
1210 return build_fold_addr_expr
1211 (fold_build2 (MEM_REF,
1212 TREE_TYPE (TREE_TYPE (op0)),
1213 unshare_expr (op0), off));
1216 return fold_binary_loc (loc, subcode,
1217 gimple_expr_type (stmt), op0, op1);
1220 case GIMPLE_TERNARY_RHS:
1222 /* Handle ternary operators that can appear in GIMPLE form. */
1223 tree op0 = valueize_op (gimple_assign_rhs1 (stmt));
1224 tree op1 = valueize_op (gimple_assign_rhs2 (stmt));
1225 tree op2 = valueize_op (gimple_assign_rhs3 (stmt));
1227 return fold_ternary_loc (loc, subcode,
1228 gimple_expr_type (stmt), op0, op1, op2);
1239 tree fn = valueize_op (gimple_call_fn (stmt));
1240 if (TREE_CODE (fn) == ADDR_EXPR
1241 && TREE_CODE (TREE_OPERAND (fn, 0)) == FUNCTION_DECL
1242 && DECL_BUILT_IN (TREE_OPERAND (fn, 0)))
1244 tree *args = XALLOCAVEC (tree, gimple_call_num_args (stmt));
1247 for (i = 0; i < gimple_call_num_args (stmt); ++i)
1248 args[i] = valueize_op (gimple_call_arg (stmt, i));
1249 call = build_call_array_loc (loc,
1250 gimple_call_return_type (stmt),
1251 fn, gimple_call_num_args (stmt), args);
1252 retval = fold_call_expr (EXPR_LOCATION (call), call, false);
1254 /* fold_call_expr wraps the result inside a NOP_EXPR. */
1255 STRIP_NOPS (retval);
1263 /* Handle comparison operators that can appear in GIMPLE form. */
1264 tree op0 = valueize_op (gimple_cond_lhs (stmt));
1265 tree op1 = valueize_op (gimple_cond_rhs (stmt));
1266 enum tree_code code = gimple_cond_code (stmt);
1267 return fold_binary_loc (loc, code, boolean_type_node, op0, op1);
1272 /* Return the constant switch index. */
1273 return valueize_op (gimple_switch_index (stmt));
1281 /* Return the tree representing the element referenced by T if T is an
1282 ARRAY_REF or COMPONENT_REF into constant aggregates. Return
1283 NULL_TREE otherwise. */
1286 fold_const_aggregate_ref (tree t)
1288 tree base, ctor, idx, field;
1289 unsigned HOST_WIDE_INT cnt;
1293 if (TREE_CODE_CLASS (TREE_CODE (t)) == tcc_declaration)
1294 return get_symbol_constant_value (t);
1296 switch (TREE_CODE (t))
1299 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1300 DECL_INITIAL. If BASE is a nested reference into another
1301 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1302 the inner reference. */
1303 base = TREE_OPERAND (t, 0);
1304 switch (TREE_CODE (base))
1307 /* ??? We could handle this case. */
1308 if (!integer_zerop (TREE_OPERAND (base, 1)))
1310 base = get_base_address (base);
1312 || TREE_CODE (base) != VAR_DECL)
1317 if (!TREE_READONLY (base)
1318 || TREE_CODE (TREE_TYPE (base)) != ARRAY_TYPE
1319 || !targetm.binds_local_p (base))
1322 ctor = DECL_INITIAL (base);
1327 ctor = fold_const_aggregate_ref (base);
1339 if (ctor == NULL_TREE
1340 || (TREE_CODE (ctor) != CONSTRUCTOR
1341 && TREE_CODE (ctor) != STRING_CST)
1342 || !TREE_STATIC (ctor))
1345 /* Get the index. If we have an SSA_NAME, try to resolve it
1346 with the current lattice value for the SSA_NAME. */
1347 idx = TREE_OPERAND (t, 1);
1348 switch (TREE_CODE (idx))
1351 if ((tem = get_constant_value (idx))
1352 && TREE_CODE (tem) == INTEGER_CST)
1365 /* Fold read from constant string. */
1366 if (TREE_CODE (ctor) == STRING_CST)
1368 if ((TYPE_MODE (TREE_TYPE (t))
1369 == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1370 && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1372 && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) == 1
1373 && compare_tree_int (idx, TREE_STRING_LENGTH (ctor)) < 0)
1374 return build_int_cst_type (TREE_TYPE (t),
1375 (TREE_STRING_POINTER (ctor)
1376 [TREE_INT_CST_LOW (idx)]));
1380 /* Whoo-hoo! I'll fold ya baby. Yeah! */
1381 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
1382 if (tree_int_cst_equal (cfield, idx))
1385 if (TREE_CODE (cval) == ADDR_EXPR)
1387 tree base = get_base_address (TREE_OPERAND (cval, 0));
1388 if (base && TREE_CODE (base) == VAR_DECL)
1389 add_referenced_var (base);
1396 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1397 DECL_INITIAL. If BASE is a nested reference into another
1398 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1399 the inner reference. */
1400 base = TREE_OPERAND (t, 0);
1401 switch (TREE_CODE (base))
1404 if (!TREE_READONLY (base)
1405 || TREE_CODE (TREE_TYPE (base)) != RECORD_TYPE
1406 || !targetm.binds_local_p (base))
1409 ctor = DECL_INITIAL (base);
1414 ctor = fold_const_aggregate_ref (base);
1421 if (ctor == NULL_TREE
1422 || TREE_CODE (ctor) != CONSTRUCTOR
1423 || !TREE_STATIC (ctor))
1426 field = TREE_OPERAND (t, 1);
1428 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
1430 /* FIXME: Handle bit-fields. */
1431 && ! DECL_BIT_FIELD (cfield))
1434 if (TREE_CODE (cval) == ADDR_EXPR)
1436 tree base = get_base_address (TREE_OPERAND (cval, 0));
1437 if (base && TREE_CODE (base) == VAR_DECL)
1438 add_referenced_var (base);
1447 tree c = fold_const_aggregate_ref (TREE_OPERAND (t, 0));
1448 if (c && TREE_CODE (c) == COMPLEX_CST)
1449 return fold_build1_loc (EXPR_LOCATION (t),
1450 TREE_CODE (t), TREE_TYPE (t), c);
1455 /* Get the base object we are accessing. */
1456 base = TREE_OPERAND (t, 0);
1457 if (TREE_CODE (base) == SSA_NAME
1458 && (tem = get_constant_value (base)))
1460 if (TREE_CODE (base) != ADDR_EXPR)
1462 base = TREE_OPERAND (base, 0);
1463 switch (TREE_CODE (base))
1467 && !AGGREGATE_TYPE_P (TREE_TYPE (base))
1468 && integer_zerop (TREE_OPERAND (t, 1)))
1470 tree res = get_symbol_constant_value (base);
1472 && !useless_type_conversion_p
1473 (TREE_TYPE (t), TREE_TYPE (res)))
1474 res = fold_unary (VIEW_CONVERT_EXPR, TREE_TYPE (t), res);
1478 if (!TREE_READONLY (base)
1479 || TREE_CODE (TREE_TYPE (base)) != ARRAY_TYPE
1480 || !targetm.binds_local_p (base))
1483 ctor = DECL_INITIAL (base);
1495 if (ctor == NULL_TREE
1496 || (TREE_CODE (ctor) != CONSTRUCTOR
1497 && TREE_CODE (ctor) != STRING_CST)
1498 || !TREE_STATIC (ctor))
1501 /* Get the byte offset. */
1502 idx = TREE_OPERAND (t, 1);
1504 /* Fold read from constant string. */
1505 if (TREE_CODE (ctor) == STRING_CST)
1507 if ((TYPE_MODE (TREE_TYPE (t))
1508 == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1509 && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1511 && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) == 1
1512 && compare_tree_int (idx, TREE_STRING_LENGTH (ctor)) < 0)
1513 return build_int_cst_type (TREE_TYPE (t),
1514 (TREE_STRING_POINTER (ctor)
1515 [TREE_INT_CST_LOW (idx)]));
1519 /* ??? Implement byte-offset indexing into a non-array CONSTRUCTOR. */
1520 if (TREE_CODE (TREE_TYPE (ctor)) == ARRAY_TYPE
1521 && (TYPE_MODE (TREE_TYPE (t))
1522 == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
1523 && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (t))) != 0
1526 (TRUNC_MOD_EXPR, idx,
1527 size_int (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (t)))), 0)))
1529 idx = int_const_binop (TRUNC_DIV_EXPR, idx,
1530 size_int (GET_MODE_SIZE
1531 (TYPE_MODE (TREE_TYPE (t)))), 0);
1532 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
1533 if (tree_int_cst_equal (cfield, idx))
1536 if (TREE_CODE (cval) == ADDR_EXPR)
1538 tree base = get_base_address (TREE_OPERAND (cval, 0));
1539 if (base && TREE_CODE (base) == VAR_DECL)
1540 add_referenced_var (base);
1542 if (useless_type_conversion_p (TREE_TYPE (t), TREE_TYPE (cval)))
1544 else if (CONSTANT_CLASS_P (cval))
1545 return fold_build1 (VIEW_CONVERT_EXPR, TREE_TYPE (t), cval);
1559 /* Apply the operation CODE in type TYPE to the value, mask pair
1560 RVAL and RMASK representing a value of type RTYPE and set
1561 the value, mask pair *VAL and *MASK to the result. */
1564 bit_value_unop_1 (enum tree_code code, tree type,
1565 double_int *val, double_int *mask,
1566 tree rtype, double_int rval, double_int rmask)
1572 *val = double_int_not (rval);
1577 double_int temv, temm;
1578 /* Return ~rval + 1. */
1579 bit_value_unop_1 (BIT_NOT_EXPR, type, &temv, &temm, type, rval, rmask);
1580 bit_value_binop_1 (PLUS_EXPR, type, val, mask,
1582 type, double_int_one, double_int_zero);
1590 /* First extend mask and value according to the original type. */
1591 uns = (TREE_CODE (rtype) == INTEGER_TYPE && TYPE_IS_SIZETYPE (rtype)
1592 ? 0 : TYPE_UNSIGNED (rtype));
1593 *mask = double_int_ext (rmask, TYPE_PRECISION (rtype), uns);
1594 *val = double_int_ext (rval, TYPE_PRECISION (rtype), uns);
1596 /* Then extend mask and value according to the target type. */
1597 uns = (TREE_CODE (type) == INTEGER_TYPE && TYPE_IS_SIZETYPE (type)
1598 ? 0 : TYPE_UNSIGNED (type));
1599 *mask = double_int_ext (*mask, TYPE_PRECISION (type), uns);
1600 *val = double_int_ext (*val, TYPE_PRECISION (type), uns);
1605 *mask = double_int_minus_one;
1610 /* Apply the operation CODE in type TYPE to the value, mask pairs
1611 R1VAL, R1MASK and R2VAL, R2MASK representing a values of type R1TYPE
1612 and R2TYPE and set the value, mask pair *VAL and *MASK to the result. */
1615 bit_value_binop_1 (enum tree_code code, tree type,
1616 double_int *val, double_int *mask,
1617 tree r1type, double_int r1val, double_int r1mask,
1618 tree r2type, double_int r2val, double_int r2mask)
1620 bool uns = (TREE_CODE (type) == INTEGER_TYPE
1621 && TYPE_IS_SIZETYPE (type) ? 0 : TYPE_UNSIGNED (type));
1622 /* Assume we'll get a constant result. Use an initial varying value,
1623 we fall back to varying in the end if necessary. */
1624 *mask = double_int_minus_one;
1628 /* The mask is constant where there is a known not
1629 set bit, (m1 | m2) & ((v1 | m1) & (v2 | m2)) */
1630 *mask = double_int_and (double_int_ior (r1mask, r2mask),
1631 double_int_and (double_int_ior (r1val, r1mask),
1632 double_int_ior (r2val, r2mask)));
1633 *val = double_int_and (r1val, r2val);
1637 /* The mask is constant where there is a known
1638 set bit, (m1 | m2) & ~((v1 & ~m1) | (v2 & ~m2)). */
1639 *mask = double_int_and_not
1640 (double_int_ior (r1mask, r2mask),
1641 double_int_ior (double_int_and_not (r1val, r1mask),
1642 double_int_and_not (r2val, r2mask)));
1643 *val = double_int_ior (r1val, r2val);
1648 *mask = double_int_ior (r1mask, r2mask);
1649 *val = double_int_xor (r1val, r2val);
1654 if (double_int_zero_p (r2mask))
1656 HOST_WIDE_INT shift = r2val.low;
1657 if (code == RROTATE_EXPR)
1659 *mask = double_int_lrotate (r1mask, shift, TYPE_PRECISION (type));
1660 *val = double_int_lrotate (r1val, shift, TYPE_PRECISION (type));
1666 /* ??? We can handle partially known shift counts if we know
1667 its sign. That way we can tell that (x << (y | 8)) & 255
1669 if (double_int_zero_p (r2mask))
1671 HOST_WIDE_INT shift = r2val.low;
1672 if (code == RSHIFT_EXPR)
1674 /* We need to know if we are doing a left or a right shift
1675 to properly shift in zeros for left shift and unsigned
1676 right shifts and the sign bit for signed right shifts.
1677 For signed right shifts we shift in varying in case
1678 the sign bit was varying. */
1681 *mask = double_int_lshift (r1mask, shift,
1682 TYPE_PRECISION (type), false);
1683 *val = double_int_lshift (r1val, shift,
1684 TYPE_PRECISION (type), false);
1689 *mask = double_int_rshift (r1mask, shift,
1690 TYPE_PRECISION (type), !uns);
1691 *val = double_int_rshift (r1val, shift,
1692 TYPE_PRECISION (type), !uns);
1703 case POINTER_PLUS_EXPR:
1706 /* Do the addition with unknown bits set to zero, to give carry-ins of
1707 zero wherever possible. */
1708 lo = double_int_add (double_int_and_not (r1val, r1mask),
1709 double_int_and_not (r2val, r2mask));
1710 lo = double_int_ext (lo, TYPE_PRECISION (type), uns);
1711 /* Do the addition with unknown bits set to one, to give carry-ins of
1712 one wherever possible. */
1713 hi = double_int_add (double_int_ior (r1val, r1mask),
1714 double_int_ior (r2val, r2mask));
1715 hi = double_int_ext (hi, TYPE_PRECISION (type), uns);
1716 /* Each bit in the result is known if (a) the corresponding bits in
1717 both inputs are known, and (b) the carry-in to that bit position
1718 is known. We can check condition (b) by seeing if we got the same
1719 result with minimised carries as with maximised carries. */
1720 *mask = double_int_ior (double_int_ior (r1mask, r2mask),
1721 double_int_xor (lo, hi));
1722 *mask = double_int_ext (*mask, TYPE_PRECISION (type), uns);
1723 /* It shouldn't matter whether we choose lo or hi here. */
1730 double_int temv, temm;
1731 bit_value_unop_1 (NEGATE_EXPR, r2type, &temv, &temm,
1732 r2type, r2val, r2mask);
1733 bit_value_binop_1 (PLUS_EXPR, type, val, mask,
1734 r1type, r1val, r1mask,
1735 r2type, temv, temm);
1741 /* Just track trailing zeros in both operands and transfer
1742 them to the other. */
1743 int r1tz = double_int_ctz (double_int_ior (r1val, r1mask));
1744 int r2tz = double_int_ctz (double_int_ior (r2val, r2mask));
1745 if (r1tz + r2tz >= HOST_BITS_PER_DOUBLE_INT)
1747 *mask = double_int_zero;
1748 *val = double_int_zero;
1750 else if (r1tz + r2tz > 0)
1752 *mask = double_int_not (double_int_mask (r1tz + r2tz));
1753 *mask = double_int_ext (*mask, TYPE_PRECISION (type), uns);
1754 *val = double_int_zero;
1762 double_int m = double_int_ior (r1mask, r2mask);
1763 if (!double_int_equal_p (double_int_and_not (r1val, m),
1764 double_int_and_not (r2val, m)))
1766 *mask = double_int_zero;
1767 *val = ((code == EQ_EXPR) ? double_int_zero : double_int_one);
1771 /* We know the result of a comparison is always one or zero. */
1772 *mask = double_int_one;
1773 *val = double_int_zero;
1781 double_int tem = r1val;
1787 code = swap_tree_comparison (code);
1794 /* If the most significant bits are not known we know nothing. */
1795 if (double_int_negative_p (r1mask) || double_int_negative_p (r2mask))
1798 /* If we know the most significant bits we know the values
1799 value ranges by means of treating varying bits as zero
1800 or one. Do a cross comparison of the max/min pairs. */
1801 maxmin = double_int_cmp (double_int_ior (r1val, r1mask),
1802 double_int_and_not (r2val, r2mask), uns);
1803 minmax = double_int_cmp (double_int_and_not (r1val, r1mask),
1804 double_int_ior (r2val, r2mask), uns);
1805 if (maxmin < 0) /* r1 is less than r2. */
1807 *mask = double_int_zero;
1808 *val = double_int_one;
1810 else if (minmax > 0) /* r1 is not less or equal to r2. */
1812 *mask = double_int_zero;
1813 *val = double_int_zero;
1815 else if (maxmin == minmax) /* r1 and r2 are equal. */
1817 /* This probably should never happen as we'd have
1818 folded the thing during fully constant value folding. */
1819 *mask = double_int_zero;
1820 *val = (code == LE_EXPR ? double_int_one : double_int_zero);
1824 /* We know the result of a comparison is always one or zero. */
1825 *mask = double_int_one;
1826 *val = double_int_zero;
1835 /* Return the propagation value when applying the operation CODE to
1836 the value RHS yielding type TYPE. */
1839 bit_value_unop (enum tree_code code, tree type, tree rhs)
1841 prop_value_t rval = get_value_for_expr (rhs, true);
1842 double_int value, mask;
1844 gcc_assert ((rval.lattice_val == CONSTANT
1845 && TREE_CODE (rval.value) == INTEGER_CST)
1846 || double_int_minus_one_p (rval.mask));
1847 bit_value_unop_1 (code, type, &value, &mask,
1848 TREE_TYPE (rhs), value_to_double_int (rval), rval.mask);
1849 if (!double_int_minus_one_p (mask))
1851 val.lattice_val = CONSTANT;
1853 /* ??? Delay building trees here. */
1854 val.value = double_int_to_tree (type, value);
1858 val.lattice_val = VARYING;
1859 val.value = NULL_TREE;
1860 val.mask = double_int_minus_one;
1865 /* Return the propagation value when applying the operation CODE to
1866 the values RHS1 and RHS2 yielding type TYPE. */
1869 bit_value_binop (enum tree_code code, tree type, tree rhs1, tree rhs2)
1871 prop_value_t r1val = get_value_for_expr (rhs1, true);
1872 prop_value_t r2val = get_value_for_expr (rhs2, true);
1873 double_int value, mask;
1875 gcc_assert ((r1val.lattice_val == CONSTANT
1876 && TREE_CODE (r1val.value) == INTEGER_CST)
1877 || double_int_minus_one_p (r1val.mask));
1878 gcc_assert ((r2val.lattice_val == CONSTANT
1879 && TREE_CODE (r2val.value) == INTEGER_CST)
1880 || double_int_minus_one_p (r2val.mask));
1881 bit_value_binop_1 (code, type, &value, &mask,
1882 TREE_TYPE (rhs1), value_to_double_int (r1val), r1val.mask,
1883 TREE_TYPE (rhs2), value_to_double_int (r2val), r2val.mask);
1884 if (!double_int_minus_one_p (mask))
1886 val.lattice_val = CONSTANT;
1888 /* ??? Delay building trees here. */
1889 val.value = double_int_to_tree (type, value);
1893 val.lattice_val = VARYING;
1894 val.value = NULL_TREE;
1895 val.mask = double_int_minus_one;
1900 /* Evaluate statement STMT.
1901 Valid only for assignments, calls, conditionals, and switches. */
1904 evaluate_stmt (gimple stmt)
1907 tree simplified = NULL_TREE;
1908 ccp_lattice_t likelyvalue = likely_value (stmt);
1909 bool is_constant = false;
1911 if (dump_file && (dump_flags & TDF_DETAILS))
1913 fprintf (dump_file, "which is likely ");
1914 switch (likelyvalue)
1917 fprintf (dump_file, "CONSTANT");
1920 fprintf (dump_file, "UNDEFINED");
1923 fprintf (dump_file, "VARYING");
1927 fprintf (dump_file, "\n");
1930 /* If the statement is likely to have a CONSTANT result, then try
1931 to fold the statement to determine the constant value. */
1932 /* FIXME. This is the only place that we call ccp_fold.
1933 Since likely_value never returns CONSTANT for calls, we will
1934 not attempt to fold them, including builtins that may profit. */
1935 if (likelyvalue == CONSTANT)
1937 fold_defer_overflow_warnings ();
1938 simplified = ccp_fold (stmt);
1939 is_constant = simplified && is_gimple_min_invariant (simplified);
1940 fold_undefer_overflow_warnings (is_constant, stmt, 0);
1943 /* The statement produced a constant value. */
1944 val.lattice_val = CONSTANT;
1945 val.value = simplified;
1946 val.mask = double_int_zero;
1949 /* If the statement is likely to have a VARYING result, then do not
1950 bother folding the statement. */
1951 else if (likelyvalue == VARYING)
1953 enum gimple_code code = gimple_code (stmt);
1954 if (code == GIMPLE_ASSIGN)
1956 enum tree_code subcode = gimple_assign_rhs_code (stmt);
1958 /* Other cases cannot satisfy is_gimple_min_invariant
1960 if (get_gimple_rhs_class (subcode) == GIMPLE_SINGLE_RHS)
1961 simplified = gimple_assign_rhs1 (stmt);
1963 else if (code == GIMPLE_SWITCH)
1964 simplified = gimple_switch_index (stmt);
1966 /* These cannot satisfy is_gimple_min_invariant without folding. */
1967 gcc_assert (code == GIMPLE_CALL || code == GIMPLE_COND);
1968 is_constant = simplified && is_gimple_min_invariant (simplified);
1971 /* The statement produced a constant value. */
1972 val.lattice_val = CONSTANT;
1973 val.value = simplified;
1974 val.mask = double_int_zero;
1978 /* Resort to simplification for bitwise tracking. */
1979 if (flag_tree_bit_ccp
1980 && likelyvalue == CONSTANT
1983 enum gimple_code code = gimple_code (stmt);
1984 val.lattice_val = VARYING;
1985 val.value = NULL_TREE;
1986 val.mask = double_int_minus_one;
1987 if (code == GIMPLE_ASSIGN)
1989 enum tree_code subcode = gimple_assign_rhs_code (stmt);
1990 tree rhs1 = gimple_assign_rhs1 (stmt);
1991 switch (get_gimple_rhs_class (subcode))
1993 case GIMPLE_SINGLE_RHS:
1994 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
1995 || POINTER_TYPE_P (TREE_TYPE (rhs1)))
1996 val = get_value_for_expr (rhs1, true);
1999 case GIMPLE_UNARY_RHS:
2000 if ((INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
2001 || POINTER_TYPE_P (TREE_TYPE (rhs1)))
2002 && (INTEGRAL_TYPE_P (gimple_expr_type (stmt))
2003 || POINTER_TYPE_P (gimple_expr_type (stmt))))
2004 val = bit_value_unop (subcode, gimple_expr_type (stmt), rhs1);
2007 case GIMPLE_BINARY_RHS:
2008 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
2009 || POINTER_TYPE_P (TREE_TYPE (rhs1)))
2011 tree rhs2 = gimple_assign_rhs2 (stmt);
2012 val = bit_value_binop (subcode,
2013 TREE_TYPE (rhs1), rhs1, rhs2);
2020 else if (code == GIMPLE_COND)
2022 enum tree_code code = gimple_cond_code (stmt);
2023 tree rhs1 = gimple_cond_lhs (stmt);
2024 tree rhs2 = gimple_cond_rhs (stmt);
2025 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
2026 || POINTER_TYPE_P (TREE_TYPE (rhs1)))
2027 val = bit_value_binop (code, TREE_TYPE (rhs1), rhs1, rhs2);
2029 is_constant = (val.lattice_val == CONSTANT);
2034 /* The statement produced a nonconstant value. If the statement
2035 had UNDEFINED operands, then the result of the statement
2036 should be UNDEFINED. Otherwise, the statement is VARYING. */
2037 if (likelyvalue == UNDEFINED)
2039 val.lattice_val = likelyvalue;
2040 val.mask = double_int_zero;
2044 val.lattice_val = VARYING;
2045 val.mask = double_int_minus_one;
2048 val.value = NULL_TREE;
2054 /* Fold the stmt at *GSI with CCP specific information that propagating
2055 and regular folding does not catch. */
2058 ccp_fold_stmt (gimple_stmt_iterator *gsi)
2060 gimple stmt = gsi_stmt (*gsi);
2062 switch (gimple_code (stmt))
2067 /* Statement evaluation will handle type mismatches in constants
2068 more gracefully than the final propagation. This allows us to
2069 fold more conditionals here. */
2070 val = evaluate_stmt (stmt);
2071 if (val.lattice_val != CONSTANT
2072 || !double_int_zero_p (val.mask))
2077 fprintf (dump_file, "Folding predicate ");
2078 print_gimple_expr (dump_file, stmt, 0, 0);
2079 fprintf (dump_file, " to ");
2080 print_generic_expr (dump_file, val.value, 0);
2081 fprintf (dump_file, "\n");
2084 if (integer_zerop (val.value))
2085 gimple_cond_make_false (stmt);
2087 gimple_cond_make_true (stmt);
2094 tree lhs = gimple_call_lhs (stmt);
2097 bool changed = false;
2100 /* If the call was folded into a constant make sure it goes
2101 away even if we cannot propagate into all uses because of
2104 && TREE_CODE (lhs) == SSA_NAME
2105 && (val = get_constant_value (lhs)))
2107 tree new_rhs = unshare_expr (val);
2109 if (!useless_type_conversion_p (TREE_TYPE (lhs),
2110 TREE_TYPE (new_rhs)))
2111 new_rhs = fold_convert (TREE_TYPE (lhs), new_rhs);
2112 res = update_call_from_tree (gsi, new_rhs);
2117 /* Propagate into the call arguments. Compared to replace_uses_in
2118 this can use the argument slot types for type verification
2119 instead of the current argument type. We also can safely
2120 drop qualifiers here as we are dealing with constants anyway. */
2121 argt = TYPE_ARG_TYPES (TREE_TYPE (TREE_TYPE (gimple_call_fn (stmt))));
2122 for (i = 0; i < gimple_call_num_args (stmt) && argt;
2123 ++i, argt = TREE_CHAIN (argt))
2125 tree arg = gimple_call_arg (stmt, i);
2126 if (TREE_CODE (arg) == SSA_NAME
2127 && (val = get_constant_value (arg))
2128 && useless_type_conversion_p
2129 (TYPE_MAIN_VARIANT (TREE_VALUE (argt)),
2130 TYPE_MAIN_VARIANT (TREE_TYPE (val))))
2132 gimple_call_set_arg (stmt, i, unshare_expr (val));
2142 tree lhs = gimple_assign_lhs (stmt);
2145 /* If we have a load that turned out to be constant replace it
2146 as we cannot propagate into all uses in all cases. */
2147 if (gimple_assign_single_p (stmt)
2148 && TREE_CODE (lhs) == SSA_NAME
2149 && (val = get_constant_value (lhs)))
2151 tree rhs = unshare_expr (val);
2152 if (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (rhs)))
2153 rhs = fold_build1 (VIEW_CONVERT_EXPR, TREE_TYPE (lhs), rhs);
2154 gimple_assign_set_rhs_from_tree (gsi, rhs);
2166 /* Visit the assignment statement STMT. Set the value of its LHS to the
2167 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
2168 creates virtual definitions, set the value of each new name to that
2169 of the RHS (if we can derive a constant out of the RHS).
2170 Value-returning call statements also perform an assignment, and
2171 are handled here. */
2173 static enum ssa_prop_result
2174 visit_assignment (gimple stmt, tree *output_p)
2177 enum ssa_prop_result retval;
2179 tree lhs = gimple_get_lhs (stmt);
2181 gcc_assert (gimple_code (stmt) != GIMPLE_CALL
2182 || gimple_call_lhs (stmt) != NULL_TREE);
2184 if (gimple_assign_single_p (stmt)
2185 && gimple_assign_rhs_code (stmt) == SSA_NAME)
2186 /* For a simple copy operation, we copy the lattice values. */
2187 val = *get_value (gimple_assign_rhs1 (stmt));
2189 /* Evaluate the statement, which could be
2190 either a GIMPLE_ASSIGN or a GIMPLE_CALL. */
2191 val = evaluate_stmt (stmt);
2193 retval = SSA_PROP_NOT_INTERESTING;
2195 /* Set the lattice value of the statement's output. */
2196 if (TREE_CODE (lhs) == SSA_NAME)
2198 /* If STMT is an assignment to an SSA_NAME, we only have one
2200 if (set_lattice_value (lhs, val))
2203 if (val.lattice_val == VARYING)
2204 retval = SSA_PROP_VARYING;
2206 retval = SSA_PROP_INTERESTING;
2214 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
2215 if it can determine which edge will be taken. Otherwise, return
2216 SSA_PROP_VARYING. */
2218 static enum ssa_prop_result
2219 visit_cond_stmt (gimple stmt, edge *taken_edge_p)
2224 block = gimple_bb (stmt);
2225 val = evaluate_stmt (stmt);
2226 if (val.lattice_val != CONSTANT
2227 || !double_int_zero_p (val.mask))
2228 return SSA_PROP_VARYING;
2230 /* Find which edge out of the conditional block will be taken and add it
2231 to the worklist. If no single edge can be determined statically,
2232 return SSA_PROP_VARYING to feed all the outgoing edges to the
2233 propagation engine. */
2234 *taken_edge_p = find_taken_edge (block, val.value);
2236 return SSA_PROP_INTERESTING;
2238 return SSA_PROP_VARYING;
2242 /* Evaluate statement STMT. If the statement produces an output value and
2243 its evaluation changes the lattice value of its output, return
2244 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
2247 If STMT is a conditional branch and we can determine its truth
2248 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
2249 value, return SSA_PROP_VARYING. */
2251 static enum ssa_prop_result
2252 ccp_visit_stmt (gimple stmt, edge *taken_edge_p, tree *output_p)
2257 if (dump_file && (dump_flags & TDF_DETAILS))
2259 fprintf (dump_file, "\nVisiting statement:\n");
2260 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
2263 switch (gimple_code (stmt))
2266 /* If the statement is an assignment that produces a single
2267 output value, evaluate its RHS to see if the lattice value of
2268 its output has changed. */
2269 return visit_assignment (stmt, output_p);
2272 /* A value-returning call also performs an assignment. */
2273 if (gimple_call_lhs (stmt) != NULL_TREE)
2274 return visit_assignment (stmt, output_p);
2279 /* If STMT is a conditional branch, see if we can determine
2280 which branch will be taken. */
2281 /* FIXME. It appears that we should be able to optimize
2282 computed GOTOs here as well. */
2283 return visit_cond_stmt (stmt, taken_edge_p);
2289 /* Any other kind of statement is not interesting for constant
2290 propagation and, therefore, not worth simulating. */
2291 if (dump_file && (dump_flags & TDF_DETAILS))
2292 fprintf (dump_file, "No interesting values produced. Marked VARYING.\n");
2294 /* Definitions made by statements other than assignments to
2295 SSA_NAMEs represent unknown modifications to their outputs.
2296 Mark them VARYING. */
2297 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
2299 prop_value_t v = { VARYING, NULL_TREE, { -1, (HOST_WIDE_INT) -1 } };
2300 set_lattice_value (def, v);
2303 return SSA_PROP_VARYING;
2307 /* Main entry point for SSA Conditional Constant Propagation. */
2313 ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node);
2314 if (ccp_finalize ())
2315 return (TODO_cleanup_cfg | TODO_update_ssa | TODO_remove_unused_locals);
2324 return flag_tree_ccp != 0;
2328 struct gimple_opt_pass pass_ccp =
2333 gate_ccp, /* gate */
2334 do_ssa_ccp, /* execute */
2337 0, /* static_pass_number */
2338 TV_TREE_CCP, /* tv_id */
2339 PROP_cfg | PROP_ssa, /* properties_required */
2340 0, /* properties_provided */
2341 0, /* properties_destroyed */
2342 0, /* todo_flags_start */
2343 TODO_dump_func | TODO_verify_ssa
2344 | TODO_verify_stmts | TODO_ggc_collect/* todo_flags_finish */
2350 /* Try to optimize out __builtin_stack_restore. Optimize it out
2351 if there is another __builtin_stack_restore in the same basic
2352 block and no calls or ASM_EXPRs are in between, or if this block's
2353 only outgoing edge is to EXIT_BLOCK and there are no calls or
2354 ASM_EXPRs after this __builtin_stack_restore. */
2357 optimize_stack_restore (gimple_stmt_iterator i)
2362 basic_block bb = gsi_bb (i);
2363 gimple call = gsi_stmt (i);
2365 if (gimple_code (call) != GIMPLE_CALL
2366 || gimple_call_num_args (call) != 1
2367 || TREE_CODE (gimple_call_arg (call, 0)) != SSA_NAME
2368 || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call, 0))))
2371 for (gsi_next (&i); !gsi_end_p (i); gsi_next (&i))
2373 stmt = gsi_stmt (i);
2374 if (gimple_code (stmt) == GIMPLE_ASM)
2376 if (gimple_code (stmt) != GIMPLE_CALL)
2379 callee = gimple_call_fndecl (stmt);
2381 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
2382 /* All regular builtins are ok, just obviously not alloca. */
2383 || DECL_FUNCTION_CODE (callee) == BUILT_IN_ALLOCA)
2386 if (DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_RESTORE)
2387 goto second_stack_restore;
2393 /* Allow one successor of the exit block, or zero successors. */
2394 switch (EDGE_COUNT (bb->succs))
2399 if (single_succ_edge (bb)->dest != EXIT_BLOCK_PTR)
2405 second_stack_restore:
2407 /* If there's exactly one use, then zap the call to __builtin_stack_save.
2408 If there are multiple uses, then the last one should remove the call.
2409 In any case, whether the call to __builtin_stack_save can be removed
2410 or not is irrelevant to removing the call to __builtin_stack_restore. */
2411 if (has_single_use (gimple_call_arg (call, 0)))
2413 gimple stack_save = SSA_NAME_DEF_STMT (gimple_call_arg (call, 0));
2414 if (is_gimple_call (stack_save))
2416 callee = gimple_call_fndecl (stack_save);
2418 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL
2419 && DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_SAVE)
2421 gimple_stmt_iterator stack_save_gsi;
2424 stack_save_gsi = gsi_for_stmt (stack_save);
2425 rhs = build_int_cst (TREE_TYPE (gimple_call_arg (call, 0)), 0);
2426 update_call_from_tree (&stack_save_gsi, rhs);
2431 /* No effect, so the statement will be deleted. */
2432 return integer_zero_node;
2435 /* If va_list type is a simple pointer and nothing special is needed,
2436 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
2437 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
2438 pointer assignment. */
2441 optimize_stdarg_builtin (gimple call)
2443 tree callee, lhs, rhs, cfun_va_list;
2444 bool va_list_simple_ptr;
2445 location_t loc = gimple_location (call);
2447 if (gimple_code (call) != GIMPLE_CALL)
2450 callee = gimple_call_fndecl (call);
2452 cfun_va_list = targetm.fn_abi_va_list (callee);
2453 va_list_simple_ptr = POINTER_TYPE_P (cfun_va_list)
2454 && (TREE_TYPE (cfun_va_list) == void_type_node
2455 || TREE_TYPE (cfun_va_list) == char_type_node);
2457 switch (DECL_FUNCTION_CODE (callee))
2459 case BUILT_IN_VA_START:
2460 if (!va_list_simple_ptr
2461 || targetm.expand_builtin_va_start != NULL
2462 || built_in_decls[BUILT_IN_NEXT_ARG] == NULL)
2465 if (gimple_call_num_args (call) != 2)
2468 lhs = gimple_call_arg (call, 0);
2469 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
2470 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
2471 != TYPE_MAIN_VARIANT (cfun_va_list))
2474 lhs = build_fold_indirect_ref_loc (loc, lhs);
2475 rhs = build_call_expr_loc (loc, built_in_decls[BUILT_IN_NEXT_ARG],
2476 1, integer_zero_node);
2477 rhs = fold_convert_loc (loc, TREE_TYPE (lhs), rhs);
2478 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
2480 case BUILT_IN_VA_COPY:
2481 if (!va_list_simple_ptr)
2484 if (gimple_call_num_args (call) != 2)
2487 lhs = gimple_call_arg (call, 0);
2488 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
2489 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
2490 != TYPE_MAIN_VARIANT (cfun_va_list))
2493 lhs = build_fold_indirect_ref_loc (loc, lhs);
2494 rhs = gimple_call_arg (call, 1);
2495 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs))
2496 != TYPE_MAIN_VARIANT (cfun_va_list))
2499 rhs = fold_convert_loc (loc, TREE_TYPE (lhs), rhs);
2500 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
2502 case BUILT_IN_VA_END:
2503 /* No effect, so the statement will be deleted. */
2504 return integer_zero_node;
2511 /* A simple pass that attempts to fold all builtin functions. This pass
2512 is run after we've propagated as many constants as we can. */
2515 execute_fold_all_builtins (void)
2517 bool cfg_changed = false;
2519 unsigned int todoflags = 0;
2523 gimple_stmt_iterator i;
2524 for (i = gsi_start_bb (bb); !gsi_end_p (i); )
2526 gimple stmt, old_stmt;
2527 tree callee, result;
2528 enum built_in_function fcode;
2530 stmt = gsi_stmt (i);
2532 if (gimple_code (stmt) != GIMPLE_CALL)
2537 callee = gimple_call_fndecl (stmt);
2538 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
2543 fcode = DECL_FUNCTION_CODE (callee);
2545 result = gimple_fold_builtin (stmt);
2548 gimple_remove_stmt_histograms (cfun, stmt);
2551 switch (DECL_FUNCTION_CODE (callee))
2553 case BUILT_IN_CONSTANT_P:
2554 /* Resolve __builtin_constant_p. If it hasn't been
2555 folded to integer_one_node by now, it's fairly
2556 certain that the value simply isn't constant. */
2557 result = integer_zero_node;
2560 case BUILT_IN_STACK_RESTORE:
2561 result = optimize_stack_restore (i);
2567 case BUILT_IN_VA_START:
2568 case BUILT_IN_VA_END:
2569 case BUILT_IN_VA_COPY:
2570 /* These shouldn't be folded before pass_stdarg. */
2571 result = optimize_stdarg_builtin (stmt);
2581 if (dump_file && (dump_flags & TDF_DETAILS))
2583 fprintf (dump_file, "Simplified\n ");
2584 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
2588 if (!update_call_from_tree (&i, result))
2590 gimplify_and_update_call_from_tree (&i, result);
2591 todoflags |= TODO_update_address_taken;
2594 stmt = gsi_stmt (i);
2597 if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt)
2598 && gimple_purge_dead_eh_edges (bb))
2601 if (dump_file && (dump_flags & TDF_DETAILS))
2603 fprintf (dump_file, "to\n ");
2604 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
2605 fprintf (dump_file, "\n");
2608 /* Retry the same statement if it changed into another
2609 builtin, there might be new opportunities now. */
2610 if (gimple_code (stmt) != GIMPLE_CALL)
2615 callee = gimple_call_fndecl (stmt);
2617 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
2618 || DECL_FUNCTION_CODE (callee) == fcode)
2623 /* Delete unreachable blocks. */
2625 todoflags |= TODO_cleanup_cfg;
2631 struct gimple_opt_pass pass_fold_builtins =
2637 execute_fold_all_builtins, /* execute */
2640 0, /* static_pass_number */
2641 TV_NONE, /* tv_id */
2642 PROP_cfg | PROP_ssa, /* properties_required */
2643 0, /* properties_provided */
2644 0, /* properties_destroyed */
2645 0, /* todo_flags_start */
2648 | TODO_update_ssa /* todo_flags_finish */