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
*);
171 static tree
fold_ctor_reference (tree type
, tree ctor
,
172 unsigned HOST_WIDE_INT offset
,
173 unsigned HOST_WIDE_INT size
);
175 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */
178 dump_lattice_value (FILE *outf
, const char *prefix
, prop_value_t val
)
180 switch (val
.lattice_val
)
183 fprintf (outf
, "%sUNINITIALIZED", prefix
);
186 fprintf (outf
, "%sUNDEFINED", prefix
);
189 fprintf (outf
, "%sVARYING", prefix
);
192 fprintf (outf
, "%sCONSTANT ", prefix
);
193 if (TREE_CODE (val
.value
) != INTEGER_CST
194 || double_int_zero_p (val
.mask
))
195 print_generic_expr (outf
, val
.value
, dump_flags
);
198 double_int cval
= double_int_and_not (tree_to_double_int (val
.value
),
200 fprintf (outf
, "%sCONSTANT " HOST_WIDE_INT_PRINT_DOUBLE_HEX
,
201 prefix
, cval
.high
, cval
.low
);
202 fprintf (outf
, " (" HOST_WIDE_INT_PRINT_DOUBLE_HEX
")",
203 val
.mask
.high
, val
.mask
.low
);
212 /* Print lattice value VAL to stderr. */
214 void debug_lattice_value (prop_value_t val
);
217 debug_lattice_value (prop_value_t val
)
219 dump_lattice_value (stderr
, "", val
);
220 fprintf (stderr
, "\n");
224 /* Compute a default value for variable VAR and store it in the
225 CONST_VAL array. The following rules are used to get default
228 1- Global and static variables that are declared constant are
231 2- Any other value is considered UNDEFINED. This is useful when
232 considering PHI nodes. PHI arguments that are undefined do not
233 change the constant value of the PHI node, which allows for more
234 constants to be propagated.
236 3- Variables defined by statements other than assignments and PHI
237 nodes are considered VARYING.
239 4- Initial values of variables that are not GIMPLE registers are
240 considered VARYING. */
243 get_default_value (tree var
)
245 tree sym
= SSA_NAME_VAR (var
);
246 prop_value_t val
= { UNINITIALIZED
, NULL_TREE
, { 0, 0 } };
249 stmt
= SSA_NAME_DEF_STMT (var
);
251 if (gimple_nop_p (stmt
))
253 /* Variables defined by an empty statement are those used
254 before being initialized. If VAR is a local variable, we
255 can assume initially that it is UNDEFINED, otherwise we must
256 consider it VARYING. */
257 if (is_gimple_reg (sym
)
258 && TREE_CODE (sym
) == VAR_DECL
)
259 val
.lattice_val
= UNDEFINED
;
262 val
.lattice_val
= VARYING
;
263 val
.mask
= double_int_minus_one
;
266 else if (is_gimple_assign (stmt
)
267 /* Value-returning GIMPLE_CALL statements assign to
268 a variable, and are treated similarly to GIMPLE_ASSIGN. */
269 || (is_gimple_call (stmt
)
270 && gimple_call_lhs (stmt
) != NULL_TREE
)
271 || gimple_code (stmt
) == GIMPLE_PHI
)
274 if (gimple_assign_single_p (stmt
)
275 && DECL_P (gimple_assign_rhs1 (stmt
))
276 && (cst
= get_symbol_constant_value (gimple_assign_rhs1 (stmt
))))
278 val
.lattice_val
= CONSTANT
;
282 /* Any other variable defined by an assignment or a PHI node
283 is considered UNDEFINED. */
284 val
.lattice_val
= UNDEFINED
;
288 /* Otherwise, VAR will never take on a constant value. */
289 val
.lattice_val
= VARYING
;
290 val
.mask
= double_int_minus_one
;
297 /* Get the constant value associated with variable VAR. */
299 static inline prop_value_t
*
304 if (const_val
== NULL
)
307 val
= &const_val
[SSA_NAME_VERSION (var
)];
308 if (val
->lattice_val
== UNINITIALIZED
)
309 *val
= get_default_value (var
);
311 canonicalize_float_value (val
);
316 /* Return the constant tree value associated with VAR. */
319 get_constant_value (tree var
)
322 if (TREE_CODE (var
) != SSA_NAME
)
324 if (is_gimple_min_invariant (var
))
328 val
= get_value (var
);
330 && val
->lattice_val
== CONSTANT
331 && (TREE_CODE (val
->value
) != INTEGER_CST
332 || double_int_zero_p (val
->mask
)))
337 /* Sets the value associated with VAR to VARYING. */
340 set_value_varying (tree var
)
342 prop_value_t
*val
= &const_val
[SSA_NAME_VERSION (var
)];
344 val
->lattice_val
= VARYING
;
345 val
->value
= NULL_TREE
;
346 val
->mask
= double_int_minus_one
;
349 /* For float types, modify the value of VAL to make ccp work correctly
350 for non-standard values (-0, NaN):
352 If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0.
353 If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED.
354 This is to fix the following problem (see PR 29921): Suppose we have
358 and we set value of y to NaN. This causes value of x to be set to NaN.
359 When we later determine that y is in fact VARYING, fold uses the fact
360 that HONOR_NANS is false, and we try to change the value of x to 0,
361 causing an ICE. With HONOR_NANS being false, the real appearance of
362 NaN would cause undefined behavior, though, so claiming that y (and x)
363 are UNDEFINED initially is correct. */
366 canonicalize_float_value (prop_value_t
*val
)
368 enum machine_mode mode
;
372 if (val
->lattice_val
!= CONSTANT
373 || TREE_CODE (val
->value
) != REAL_CST
)
376 d
= TREE_REAL_CST (val
->value
);
377 type
= TREE_TYPE (val
->value
);
378 mode
= TYPE_MODE (type
);
380 if (!HONOR_SIGNED_ZEROS (mode
)
381 && REAL_VALUE_MINUS_ZERO (d
))
383 val
->value
= build_real (type
, dconst0
);
387 if (!HONOR_NANS (mode
)
388 && REAL_VALUE_ISNAN (d
))
390 val
->lattice_val
= UNDEFINED
;
396 /* Return whether the lattice transition is valid. */
399 valid_lattice_transition (prop_value_t old_val
, prop_value_t new_val
)
401 /* Lattice transitions must always be monotonically increasing in
403 if (old_val
.lattice_val
< new_val
.lattice_val
)
406 if (old_val
.lattice_val
!= new_val
.lattice_val
)
409 if (!old_val
.value
&& !new_val
.value
)
412 /* Now both lattice values are CONSTANT. */
414 /* Allow transitioning from &x to &x & ~3. */
415 if (TREE_CODE (old_val
.value
) != INTEGER_CST
416 && TREE_CODE (new_val
.value
) == INTEGER_CST
)
419 /* Bit-lattices have to agree in the still valid bits. */
420 if (TREE_CODE (old_val
.value
) == INTEGER_CST
421 && TREE_CODE (new_val
.value
) == INTEGER_CST
)
422 return double_int_equal_p
423 (double_int_and_not (tree_to_double_int (old_val
.value
),
425 double_int_and_not (tree_to_double_int (new_val
.value
),
428 /* Otherwise constant values have to agree. */
429 return operand_equal_p (old_val
.value
, new_val
.value
, 0);
432 /* Set the value for variable VAR to NEW_VAL. Return true if the new
433 value is different from VAR's previous value. */
436 set_lattice_value (tree var
, prop_value_t new_val
)
438 /* We can deal with old UNINITIALIZED values just fine here. */
439 prop_value_t
*old_val
= &const_val
[SSA_NAME_VERSION (var
)];
441 canonicalize_float_value (&new_val
);
443 /* We have to be careful to not go up the bitwise lattice
444 represented by the mask.
445 ??? This doesn't seem to be the best place to enforce this. */
446 if (new_val
.lattice_val
== CONSTANT
447 && old_val
->lattice_val
== CONSTANT
448 && TREE_CODE (new_val
.value
) == INTEGER_CST
449 && TREE_CODE (old_val
->value
) == INTEGER_CST
)
452 diff
= double_int_xor (tree_to_double_int (new_val
.value
),
453 tree_to_double_int (old_val
->value
));
454 new_val
.mask
= double_int_ior (new_val
.mask
,
455 double_int_ior (old_val
->mask
, diff
));
458 gcc_assert (valid_lattice_transition (*old_val
, new_val
));
460 /* If *OLD_VAL and NEW_VAL are the same, return false to inform the
461 caller that this was a non-transition. */
462 if (old_val
->lattice_val
!= new_val
.lattice_val
463 || (new_val
.lattice_val
== CONSTANT
464 && TREE_CODE (new_val
.value
) == INTEGER_CST
465 && (TREE_CODE (old_val
->value
) != INTEGER_CST
466 || !double_int_equal_p (new_val
.mask
, old_val
->mask
))))
468 /* ??? We would like to delay creation of INTEGER_CSTs from
469 partially constants here. */
471 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
473 dump_lattice_value (dump_file
, "Lattice value changed to ", new_val
);
474 fprintf (dump_file
, ". Adding SSA edges to worklist.\n");
479 gcc_assert (new_val
.lattice_val
!= UNINITIALIZED
);
486 static prop_value_t
get_value_for_expr (tree
, bool);
487 static prop_value_t
bit_value_binop (enum tree_code
, tree
, tree
, tree
);
488 static void bit_value_binop_1 (enum tree_code
, tree
, double_int
*, double_int
*,
489 tree
, double_int
, double_int
,
490 tree
, double_int
, double_int
);
492 /* Return a double_int that can be used for bitwise simplifications
496 value_to_double_int (prop_value_t val
)
499 && TREE_CODE (val
.value
) == INTEGER_CST
)
500 return tree_to_double_int (val
.value
);
502 return double_int_zero
;
505 /* Return the value for the address expression EXPR based on alignment
509 get_value_from_alignment (tree expr
)
512 HOST_WIDE_INT bitsize
, bitpos
;
514 enum machine_mode mode
;
517 gcc_assert (TREE_CODE (expr
) == ADDR_EXPR
);
519 base
= get_inner_reference (TREE_OPERAND (expr
, 0),
520 &bitsize
, &bitpos
, &offset
,
521 &mode
, &align
, &align
, false);
522 if (TREE_CODE (base
) == MEM_REF
)
523 val
= bit_value_binop (PLUS_EXPR
, TREE_TYPE (expr
),
524 TREE_OPERAND (base
, 0), TREE_OPERAND (base
, 1));
526 && ((align
= get_object_alignment (base
, BIGGEST_ALIGNMENT
))
529 val
.lattice_val
= CONSTANT
;
530 /* We assume pointers are zero-extended. */
531 val
.mask
= double_int_and_not
532 (double_int_mask (TYPE_PRECISION (TREE_TYPE (expr
))),
533 uhwi_to_double_int (align
/ BITS_PER_UNIT
- 1));
534 val
.value
= build_int_cst (TREE_TYPE (expr
), 0);
538 val
.lattice_val
= VARYING
;
539 val
.mask
= double_int_minus_one
;
540 val
.value
= NULL_TREE
;
544 double_int value
, mask
;
545 bit_value_binop_1 (PLUS_EXPR
, TREE_TYPE (expr
), &value
, &mask
,
546 TREE_TYPE (expr
), value_to_double_int (val
), val
.mask
,
548 shwi_to_double_int (bitpos
/ BITS_PER_UNIT
),
550 val
.lattice_val
= double_int_minus_one_p (mask
) ? VARYING
: CONSTANT
;
552 if (val
.lattice_val
== CONSTANT
)
553 val
.value
= double_int_to_tree (TREE_TYPE (expr
), value
);
555 val
.value
= NULL_TREE
;
557 /* ??? We should handle i * 4 and more complex expressions from
558 the offset, possibly by just expanding get_value_for_expr. */
559 if (offset
!= NULL_TREE
)
561 double_int value
, mask
;
562 prop_value_t oval
= get_value_for_expr (offset
, true);
563 bit_value_binop_1 (PLUS_EXPR
, TREE_TYPE (expr
), &value
, &mask
,
564 TREE_TYPE (expr
), value_to_double_int (val
), val
.mask
,
565 TREE_TYPE (expr
), value_to_double_int (oval
),
568 if (double_int_minus_one_p (mask
))
570 val
.lattice_val
= VARYING
;
571 val
.value
= NULL_TREE
;
575 val
.lattice_val
= CONSTANT
;
576 val
.value
= double_int_to_tree (TREE_TYPE (expr
), value
);
583 /* Return the value for the tree operand EXPR. If FOR_BITS_P is true
584 return constant bits extracted from alignment information for
585 invariant addresses. */
588 get_value_for_expr (tree expr
, bool for_bits_p
)
592 if (TREE_CODE (expr
) == SSA_NAME
)
594 val
= *get_value (expr
);
596 && val
.lattice_val
== CONSTANT
597 && TREE_CODE (val
.value
) == ADDR_EXPR
)
598 val
= get_value_from_alignment (val
.value
);
600 else if (is_gimple_min_invariant (expr
)
601 && (!for_bits_p
|| TREE_CODE (expr
) != ADDR_EXPR
))
603 val
.lattice_val
= CONSTANT
;
605 val
.mask
= double_int_zero
;
606 canonicalize_float_value (&val
);
608 else if (TREE_CODE (expr
) == ADDR_EXPR
)
609 val
= get_value_from_alignment (expr
);
612 val
.lattice_val
= VARYING
;
613 val
.mask
= double_int_minus_one
;
614 val
.value
= NULL_TREE
;
619 /* Return the likely CCP lattice value for STMT.
621 If STMT has no operands, then return CONSTANT.
623 Else if undefinedness of operands of STMT cause its value to be
624 undefined, then return UNDEFINED.
626 Else if any operands of STMT are constants, then return CONSTANT.
628 Else return VARYING. */
631 likely_value (gimple stmt
)
633 bool has_constant_operand
, has_undefined_operand
, all_undefined_operands
;
638 enum gimple_code code
= gimple_code (stmt
);
640 /* This function appears to be called only for assignments, calls,
641 conditionals, and switches, due to the logic in visit_stmt. */
642 gcc_assert (code
== GIMPLE_ASSIGN
643 || code
== GIMPLE_CALL
644 || code
== GIMPLE_COND
645 || code
== GIMPLE_SWITCH
);
647 /* If the statement has volatile operands, it won't fold to a
649 if (gimple_has_volatile_ops (stmt
))
652 /* Arrive here for more complex cases. */
653 has_constant_operand
= false;
654 has_undefined_operand
= false;
655 all_undefined_operands
= true;
656 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, iter
, SSA_OP_USE
)
658 prop_value_t
*val
= get_value (use
);
660 if (val
->lattice_val
== UNDEFINED
)
661 has_undefined_operand
= true;
663 all_undefined_operands
= false;
665 if (val
->lattice_val
== CONSTANT
)
666 has_constant_operand
= true;
669 /* There may be constants in regular rhs operands. For calls we
670 have to ignore lhs, fndecl and static chain, otherwise only
672 for (i
= (is_gimple_call (stmt
) ? 2 : 0) + gimple_has_lhs (stmt
);
673 i
< gimple_num_ops (stmt
); ++i
)
675 tree op
= gimple_op (stmt
, i
);
676 if (!op
|| TREE_CODE (op
) == SSA_NAME
)
678 if (is_gimple_min_invariant (op
))
679 has_constant_operand
= true;
682 if (has_constant_operand
)
683 all_undefined_operands
= false;
685 /* If the operation combines operands like COMPLEX_EXPR make sure to
686 not mark the result UNDEFINED if only one part of the result is
688 if (has_undefined_operand
&& all_undefined_operands
)
690 else if (code
== GIMPLE_ASSIGN
&& has_undefined_operand
)
692 switch (gimple_assign_rhs_code (stmt
))
694 /* Unary operators are handled with all_undefined_operands. */
697 case POINTER_PLUS_EXPR
:
698 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected.
699 Not bitwise operators, one VARYING operand may specify the
700 result completely. Not logical operators for the same reason.
701 Not COMPLEX_EXPR as one VARYING operand makes the result partly
702 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because
703 the undefined operand may be promoted. */
710 /* If there was an UNDEFINED operand but the result may be not UNDEFINED
711 fall back to VARYING even if there were CONSTANT operands. */
712 if (has_undefined_operand
)
715 /* We do not consider virtual operands here -- load from read-only
716 memory may have only VARYING virtual operands, but still be
718 if (has_constant_operand
719 || gimple_references_memory_p (stmt
))
725 /* Returns true if STMT cannot be constant. */
728 surely_varying_stmt_p (gimple stmt
)
730 /* If the statement has operands that we cannot handle, it cannot be
732 if (gimple_has_volatile_ops (stmt
))
735 /* If it is a call and does not return a value or is not a
736 builtin and not an indirect call, it is varying. */
737 if (is_gimple_call (stmt
))
740 if (!gimple_call_lhs (stmt
)
741 || ((fndecl
= gimple_call_fndecl (stmt
)) != NULL_TREE
742 && !DECL_BUILT_IN (fndecl
)))
746 /* Any other store operation is not interesting. */
747 else if (gimple_vdef (stmt
))
750 /* Anything other than assignments and conditional jumps are not
751 interesting for CCP. */
752 if (gimple_code (stmt
) != GIMPLE_ASSIGN
753 && gimple_code (stmt
) != GIMPLE_COND
754 && gimple_code (stmt
) != GIMPLE_SWITCH
755 && gimple_code (stmt
) != GIMPLE_CALL
)
761 /* Initialize local data structures for CCP. */
764 ccp_initialize (void)
768 const_val
= XCNEWVEC (prop_value_t
, num_ssa_names
);
770 /* Initialize simulation flags for PHI nodes and statements. */
773 gimple_stmt_iterator i
;
775 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); gsi_next (&i
))
777 gimple stmt
= gsi_stmt (i
);
780 /* If the statement is a control insn, then we do not
781 want to avoid simulating the statement once. Failure
782 to do so means that those edges will never get added. */
783 if (stmt_ends_bb_p (stmt
))
786 is_varying
= surely_varying_stmt_p (stmt
);
793 /* If the statement will not produce a constant, mark
794 all its outputs VARYING. */
795 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
796 set_value_varying (def
);
798 prop_set_simulate_again (stmt
, !is_varying
);
802 /* Now process PHI nodes. We never clear the simulate_again flag on
803 phi nodes, since we do not know which edges are executable yet,
804 except for phi nodes for virtual operands when we do not do store ccp. */
807 gimple_stmt_iterator i
;
809 for (i
= gsi_start_phis (bb
); !gsi_end_p (i
); gsi_next (&i
))
811 gimple phi
= gsi_stmt (i
);
813 if (!is_gimple_reg (gimple_phi_result (phi
)))
814 prop_set_simulate_again (phi
, false);
816 prop_set_simulate_again (phi
, true);
821 /* Debug count support. Reset the values of ssa names
822 VARYING when the total number ssa names analyzed is
823 beyond the debug count specified. */
829 for (i
= 0; i
< num_ssa_names
; i
++)
833 const_val
[i
].lattice_val
= VARYING
;
834 const_val
[i
].mask
= double_int_minus_one
;
835 const_val
[i
].value
= NULL_TREE
;
841 /* Do final substitution of propagated values, cleanup the flowgraph and
842 free allocated storage.
844 Return TRUE when something was optimized. */
849 bool something_changed
;
854 /* Derive alignment and misalignment information from partially
855 constant pointers in the lattice. */
856 for (i
= 1; i
< num_ssa_names
; ++i
)
858 tree name
= ssa_name (i
);
860 struct ptr_info_def
*pi
;
861 unsigned int tem
, align
;
864 || !POINTER_TYPE_P (TREE_TYPE (name
)))
867 val
= get_value (name
);
868 if (val
->lattice_val
!= CONSTANT
869 || TREE_CODE (val
->value
) != INTEGER_CST
)
872 /* Trailing constant bits specify the alignment, trailing value
873 bits the misalignment. */
875 align
= (tem
& -tem
);
879 pi
= get_ptr_info (name
);
881 pi
->misalign
= TREE_INT_CST_LOW (val
->value
) & (align
- 1);
884 /* Perform substitutions based on the known constant values. */
885 something_changed
= substitute_and_fold (get_constant_value
,
886 ccp_fold_stmt
, true);
890 return something_changed
;;
894 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
897 any M UNDEFINED = any
898 any M VARYING = VARYING
899 Ci M Cj = Ci if (i == j)
900 Ci M Cj = VARYING if (i != j)
904 ccp_lattice_meet (prop_value_t
*val1
, prop_value_t
*val2
)
906 if (val1
->lattice_val
== UNDEFINED
)
908 /* UNDEFINED M any = any */
911 else if (val2
->lattice_val
== UNDEFINED
)
913 /* any M UNDEFINED = any
914 Nothing to do. VAL1 already contains the value we want. */
917 else if (val1
->lattice_val
== VARYING
918 || val2
->lattice_val
== VARYING
)
920 /* any M VARYING = VARYING. */
921 val1
->lattice_val
= VARYING
;
922 val1
->mask
= double_int_minus_one
;
923 val1
->value
= NULL_TREE
;
925 else if (val1
->lattice_val
== CONSTANT
926 && val2
->lattice_val
== CONSTANT
927 && TREE_CODE (val1
->value
) == INTEGER_CST
928 && TREE_CODE (val2
->value
) == INTEGER_CST
)
930 /* Ci M Cj = Ci if (i == j)
931 Ci M Cj = VARYING if (i != j)
933 For INTEGER_CSTs mask unequal bits. If no equal bits remain,
936 = double_int_ior (double_int_ior (val1
->mask
,
938 double_int_xor (tree_to_double_int (val1
->value
),
939 tree_to_double_int (val2
->value
)));
940 if (double_int_minus_one_p (val1
->mask
))
942 val1
->lattice_val
= VARYING
;
943 val1
->value
= NULL_TREE
;
946 else if (val1
->lattice_val
== CONSTANT
947 && val2
->lattice_val
== CONSTANT
948 && simple_cst_equal (val1
->value
, val2
->value
) == 1)
950 /* Ci M Cj = Ci if (i == j)
951 Ci M Cj = VARYING if (i != j)
953 VAL1 already contains the value we want for equivalent values. */
955 else if (val1
->lattice_val
== CONSTANT
956 && val2
->lattice_val
== CONSTANT
957 && (TREE_CODE (val1
->value
) == ADDR_EXPR
958 || TREE_CODE (val2
->value
) == ADDR_EXPR
))
960 /* When not equal addresses are involved try meeting for
962 prop_value_t tem
= *val2
;
963 if (TREE_CODE (val1
->value
) == ADDR_EXPR
)
964 *val1
= get_value_for_expr (val1
->value
, true);
965 if (TREE_CODE (val2
->value
) == ADDR_EXPR
)
966 tem
= get_value_for_expr (val2
->value
, true);
967 ccp_lattice_meet (val1
, &tem
);
971 /* Any other combination is VARYING. */
972 val1
->lattice_val
= VARYING
;
973 val1
->mask
= double_int_minus_one
;
974 val1
->value
= NULL_TREE
;
979 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
980 lattice values to determine PHI_NODE's lattice value. The value of a
981 PHI node is determined calling ccp_lattice_meet with all the arguments
982 of the PHI node that are incoming via executable edges. */
984 static enum ssa_prop_result
985 ccp_visit_phi_node (gimple phi
)
988 prop_value_t
*old_val
, new_val
;
990 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
992 fprintf (dump_file
, "\nVisiting PHI node: ");
993 print_gimple_stmt (dump_file
, phi
, 0, dump_flags
);
996 old_val
= get_value (gimple_phi_result (phi
));
997 switch (old_val
->lattice_val
)
1000 return SSA_PROP_VARYING
;
1007 new_val
.lattice_val
= UNDEFINED
;
1008 new_val
.value
= NULL_TREE
;
1015 for (i
= 0; i
< gimple_phi_num_args (phi
); i
++)
1017 /* Compute the meet operator over all the PHI arguments flowing
1018 through executable edges. */
1019 edge e
= gimple_phi_arg_edge (phi
, i
);
1021 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1024 "\n Argument #%d (%d -> %d %sexecutable)\n",
1025 i
, e
->src
->index
, e
->dest
->index
,
1026 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
1029 /* If the incoming edge is executable, Compute the meet operator for
1030 the existing value of the PHI node and the current PHI argument. */
1031 if (e
->flags
& EDGE_EXECUTABLE
)
1033 tree arg
= gimple_phi_arg (phi
, i
)->def
;
1034 prop_value_t arg_val
= get_value_for_expr (arg
, false);
1036 ccp_lattice_meet (&new_val
, &arg_val
);
1038 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1040 fprintf (dump_file
, "\t");
1041 print_generic_expr (dump_file
, arg
, dump_flags
);
1042 dump_lattice_value (dump_file
, "\tValue: ", arg_val
);
1043 fprintf (dump_file
, "\n");
1046 if (new_val
.lattice_val
== VARYING
)
1051 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1053 dump_lattice_value (dump_file
, "\n PHI node value: ", new_val
);
1054 fprintf (dump_file
, "\n\n");
1057 /* Make the transition to the new value. */
1058 if (set_lattice_value (gimple_phi_result (phi
), new_val
))
1060 if (new_val
.lattice_val
== VARYING
)
1061 return SSA_PROP_VARYING
;
1063 return SSA_PROP_INTERESTING
;
1066 return SSA_PROP_NOT_INTERESTING
;
1069 /* Return the constant value for OP or OP otherwise. */
1072 valueize_op (tree op
)
1074 if (TREE_CODE (op
) == SSA_NAME
)
1076 tree tem
= get_constant_value (op
);
1083 /* CCP specific front-end to the non-destructive constant folding
1086 Attempt to simplify the RHS of STMT knowing that one or more
1087 operands are constants.
1089 If simplification is possible, return the simplified RHS,
1090 otherwise return the original RHS or NULL_TREE. */
1093 ccp_fold (gimple stmt
)
1095 location_t loc
= gimple_location (stmt
);
1096 switch (gimple_code (stmt
))
1100 enum tree_code subcode
= gimple_assign_rhs_code (stmt
);
1102 switch (get_gimple_rhs_class (subcode
))
1104 case GIMPLE_SINGLE_RHS
:
1106 tree rhs
= gimple_assign_rhs1 (stmt
);
1107 enum tree_code_class kind
= TREE_CODE_CLASS (subcode
);
1109 if (TREE_CODE (rhs
) == SSA_NAME
)
1111 /* If the RHS is an SSA_NAME, return its known constant value,
1113 return get_constant_value (rhs
);
1115 /* Handle propagating invariant addresses into address operations.
1116 The folding we do here matches that in tree-ssa-forwprop.c. */
1117 else if (TREE_CODE (rhs
) == ADDR_EXPR
)
1120 base
= &TREE_OPERAND (rhs
, 0);
1121 while (handled_component_p (*base
))
1122 base
= &TREE_OPERAND (*base
, 0);
1123 if (TREE_CODE (*base
) == MEM_REF
1124 && TREE_CODE (TREE_OPERAND (*base
, 0)) == SSA_NAME
)
1126 tree val
= get_constant_value (TREE_OPERAND (*base
, 0));
1128 && TREE_CODE (val
) == ADDR_EXPR
)
1130 tree ret
, save
= *base
;
1132 new_base
= fold_build2 (MEM_REF
, TREE_TYPE (*base
),
1134 TREE_OPERAND (*base
, 1));
1135 /* We need to return a new tree, not modify the IL
1136 or share parts of it. So play some tricks to
1137 avoid manually building it. */
1139 ret
= unshare_expr (rhs
);
1140 recompute_tree_invariant_for_addr_expr (ret
);
1146 else if (TREE_CODE (rhs
) == CONSTRUCTOR
1147 && TREE_CODE (TREE_TYPE (rhs
)) == VECTOR_TYPE
1148 && (CONSTRUCTOR_NELTS (rhs
)
1149 == TYPE_VECTOR_SUBPARTS (TREE_TYPE (rhs
))))
1155 FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (rhs
), i
, val
)
1157 val
= valueize_op (val
);
1158 if (TREE_CODE (val
) == INTEGER_CST
1159 || TREE_CODE (val
) == REAL_CST
1160 || TREE_CODE (val
) == FIXED_CST
)
1161 list
= tree_cons (NULL_TREE
, val
, list
);
1166 return build_vector (TREE_TYPE (rhs
), nreverse (list
));
1169 if (kind
== tcc_reference
)
1171 if ((TREE_CODE (rhs
) == VIEW_CONVERT_EXPR
1172 || TREE_CODE (rhs
) == REALPART_EXPR
1173 || TREE_CODE (rhs
) == IMAGPART_EXPR
)
1174 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == SSA_NAME
)
1176 tree val
= get_constant_value (TREE_OPERAND (rhs
, 0));
1178 return fold_unary_loc (EXPR_LOCATION (rhs
),
1180 TREE_TYPE (rhs
), val
);
1182 else if (TREE_CODE (rhs
) == MEM_REF
1183 && TREE_CODE (TREE_OPERAND (rhs
, 0)) == SSA_NAME
)
1185 tree val
= get_constant_value (TREE_OPERAND (rhs
, 0));
1187 && TREE_CODE (val
) == ADDR_EXPR
)
1189 tree tem
= fold_build2 (MEM_REF
, TREE_TYPE (rhs
),
1191 TREE_OPERAND (rhs
, 1));
1196 return fold_const_aggregate_ref (rhs
);
1198 else if (kind
== tcc_declaration
)
1199 return get_symbol_constant_value (rhs
);
1203 case GIMPLE_UNARY_RHS
:
1205 /* Handle unary operators that can appear in GIMPLE form.
1206 Note that we know the single operand must be a constant,
1207 so this should almost always return a simplified RHS. */
1208 tree lhs
= gimple_assign_lhs (stmt
);
1209 tree op0
= valueize_op (gimple_assign_rhs1 (stmt
));
1211 /* Conversions are useless for CCP purposes if they are
1212 value-preserving. Thus the restrictions that
1213 useless_type_conversion_p places for pointer type conversions
1214 do not apply here. Substitution later will only substitute to
1216 if (CONVERT_EXPR_CODE_P (subcode
)
1217 && POINTER_TYPE_P (TREE_TYPE (lhs
))
1218 && POINTER_TYPE_P (TREE_TYPE (op0
)))
1221 /* Try to re-construct array references on-the-fly. */
1222 if (!useless_type_conversion_p (TREE_TYPE (lhs
),
1224 && ((tem
= maybe_fold_offset_to_address
1226 op0
, integer_zero_node
, TREE_TYPE (lhs
)))
1233 fold_unary_ignore_overflow_loc (loc
, subcode
,
1234 gimple_expr_type (stmt
), op0
);
1237 case GIMPLE_BINARY_RHS
:
1239 /* Handle binary operators that can appear in GIMPLE form. */
1240 tree op0
= valueize_op (gimple_assign_rhs1 (stmt
));
1241 tree op1
= valueize_op (gimple_assign_rhs2 (stmt
));
1243 /* Translate &x + CST into an invariant form suitable for
1244 further propagation. */
1245 if (gimple_assign_rhs_code (stmt
) == POINTER_PLUS_EXPR
1246 && TREE_CODE (op0
) == ADDR_EXPR
1247 && TREE_CODE (op1
) == INTEGER_CST
)
1249 tree off
= fold_convert (ptr_type_node
, op1
);
1250 return build_fold_addr_expr
1251 (fold_build2 (MEM_REF
,
1252 TREE_TYPE (TREE_TYPE (op0
)),
1253 unshare_expr (op0
), off
));
1256 return fold_binary_loc (loc
, subcode
,
1257 gimple_expr_type (stmt
), op0
, op1
);
1260 case GIMPLE_TERNARY_RHS
:
1262 /* Handle ternary operators that can appear in GIMPLE form. */
1263 tree op0
= valueize_op (gimple_assign_rhs1 (stmt
));
1264 tree op1
= valueize_op (gimple_assign_rhs2 (stmt
));
1265 tree op2
= valueize_op (gimple_assign_rhs3 (stmt
));
1267 return fold_ternary_loc (loc
, subcode
,
1268 gimple_expr_type (stmt
), op0
, op1
, op2
);
1279 tree fn
= valueize_op (gimple_call_fn (stmt
));
1280 if (TREE_CODE (fn
) == ADDR_EXPR
1281 && TREE_CODE (TREE_OPERAND (fn
, 0)) == FUNCTION_DECL
1282 && DECL_BUILT_IN (TREE_OPERAND (fn
, 0)))
1284 tree
*args
= XALLOCAVEC (tree
, gimple_call_num_args (stmt
));
1287 for (i
= 0; i
< gimple_call_num_args (stmt
); ++i
)
1288 args
[i
] = valueize_op (gimple_call_arg (stmt
, i
));
1289 call
= build_call_array_loc (loc
,
1290 gimple_call_return_type (stmt
),
1291 fn
, gimple_call_num_args (stmt
), args
);
1292 retval
= fold_call_expr (EXPR_LOCATION (call
), call
, false);
1294 /* fold_call_expr wraps the result inside a NOP_EXPR. */
1295 STRIP_NOPS (retval
);
1303 /* Handle comparison operators that can appear in GIMPLE form. */
1304 tree op0
= valueize_op (gimple_cond_lhs (stmt
));
1305 tree op1
= valueize_op (gimple_cond_rhs (stmt
));
1306 enum tree_code code
= gimple_cond_code (stmt
);
1307 return fold_binary_loc (loc
, code
, boolean_type_node
, op0
, op1
);
1312 /* Return the constant switch index. */
1313 return valueize_op (gimple_switch_index (stmt
));
1321 /* See if we can find constructor defining value of BASE.
1322 When we know the consructor with constant offset (such as
1323 base is array[40] and we do know constructor of array), then
1324 BIT_OFFSET is adjusted accordingly.
1326 As a special case, return error_mark_node when constructor
1327 is not explicitly available, but it is known to be zero
1328 such as 'static const int a;'. */
1330 get_base_constructor (tree base
, HOST_WIDE_INT
*bit_offset
)
1332 HOST_WIDE_INT bit_offset2
, size
, max_size
;
1333 if (TREE_CODE (base
) == MEM_REF
)
1335 if (!integer_zerop (TREE_OPERAND (base
, 1)))
1337 if (!host_integerp (TREE_OPERAND (base
, 1), 0))
1339 *bit_offset
+= (mem_ref_offset (base
).low
1343 base
= get_constant_value (TREE_OPERAND (base
, 0));
1344 if (!base
|| TREE_CODE (base
) != ADDR_EXPR
)
1346 base
= TREE_OPERAND (base
, 0);
1349 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its
1350 DECL_INITIAL. If BASE is a nested reference into another
1351 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
1352 the inner reference. */
1353 switch (TREE_CODE (base
))
1356 if (!const_value_known_p (base
))
1361 if (!DECL_INITIAL (base
)
1362 && (TREE_STATIC (base
) || DECL_EXTERNAL (base
)))
1363 return error_mark_node
;
1364 return DECL_INITIAL (base
);
1368 base
= get_ref_base_and_extent (base
, &bit_offset2
, &size
, &max_size
);
1369 if (max_size
== -1 || size
!= max_size
)
1371 *bit_offset
+= bit_offset2
;
1372 return get_base_constructor (base
, bit_offset
);
1383 /* CTOR is STRING_CST. Fold reference of type TYPE and size SIZE
1384 to the memory at bit OFFSET.
1386 We do only simple job of folding byte accesses. */
1389 fold_string_cst_ctor_reference (tree type
, tree ctor
, unsigned HOST_WIDE_INT offset
,
1390 unsigned HOST_WIDE_INT size
)
1392 if (INTEGRAL_TYPE_P (type
)
1393 && (TYPE_MODE (type
)
1394 == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor
))))
1395 && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor
))))
1397 && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor
)))) == 1
1398 && size
== BITS_PER_UNIT
1399 && !(offset
% BITS_PER_UNIT
))
1401 offset
/= BITS_PER_UNIT
;
1402 if (offset
< (unsigned HOST_WIDE_INT
) TREE_STRING_LENGTH (ctor
))
1403 return build_int_cst_type (type
, (TREE_STRING_POINTER (ctor
)
1406 const char a[20]="hello";
1409 might lead to offset greater than string length. In this case we
1410 know value is either initialized to 0 or out of bounds. Return 0
1412 return build_zero_cst (type
);
1417 /* CTOR is CONSTRUCTOR of an array type. Fold reference of type TYPE and size
1418 SIZE to the memory at bit OFFSET. */
1421 fold_array_ctor_reference (tree type
, tree ctor
,
1422 unsigned HOST_WIDE_INT offset
,
1423 unsigned HOST_WIDE_INT size
)
1425 unsigned HOST_WIDE_INT cnt
;
1427 double_int low_bound
, elt_size
;
1428 double_int index
, max_index
;
1429 double_int access_index
;
1430 tree domain_type
= TYPE_DOMAIN (TREE_TYPE (ctor
));
1431 HOST_WIDE_INT inner_offset
;
1433 /* Compute low bound and elt size. */
1434 if (domain_type
&& TYPE_MIN_VALUE (domain_type
))
1436 /* Static constructors for variably sized objects makes no sense. */
1437 gcc_assert (TREE_CODE (TYPE_MIN_VALUE (domain_type
)) == INTEGER_CST
);
1438 low_bound
= tree_to_double_int (TYPE_MIN_VALUE (domain_type
));
1441 low_bound
= double_int_zero
;
1442 /* Static constructors for variably sized objects makes no sense. */
1443 gcc_assert (TREE_CODE(TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (ctor
))))
1446 tree_to_double_int (TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (ctor
))));
1449 /* We can handle only constantly sized accesses that are known to not
1450 be larger than size of array element. */
1451 if (!TYPE_SIZE_UNIT (type
)
1452 || TREE_CODE (TYPE_SIZE_UNIT (type
)) != INTEGER_CST
1453 || double_int_cmp (elt_size
,
1454 tree_to_double_int (TYPE_SIZE_UNIT (type
)), 0) < 0)
1457 /* Compute the array index we look for. */
1458 access_index
= double_int_udiv (uhwi_to_double_int (offset
/ BITS_PER_UNIT
),
1459 elt_size
, TRUNC_DIV_EXPR
);
1460 access_index
= double_int_add (access_index
, low_bound
);
1462 /* And offset within the access. */
1463 inner_offset
= offset
% (double_int_to_uhwi (elt_size
) * BITS_PER_UNIT
);
1465 /* See if the array field is large enough to span whole access. We do not
1466 care to fold accesses spanning multiple array indexes. */
1467 if (inner_offset
+ size
> double_int_to_uhwi (elt_size
) * BITS_PER_UNIT
)
1470 index
= double_int_sub (low_bound
, double_int_one
);
1471 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor
), cnt
, cfield
, cval
)
1473 /* Array constructor might explicitely set index, or specify range
1474 or leave index NULL meaning that it is next index after previous
1478 if (TREE_CODE (cfield
) == INTEGER_CST
)
1479 max_index
= index
= tree_to_double_int (cfield
);
1482 gcc_assert (TREE_CODE (cfield
) == RANGE_EXPR
);
1483 index
= tree_to_double_int (TREE_OPERAND (cfield
, 0));
1484 max_index
= tree_to_double_int (TREE_OPERAND (cfield
, 1));
1488 max_index
= index
= double_int_add (index
, double_int_one
);
1490 /* Do we have match? */
1491 if (double_int_cmp (access_index
, index
, 1) >= 0
1492 && double_int_cmp (access_index
, max_index
, 1) <= 0)
1493 return fold_ctor_reference (type
, cval
, inner_offset
, size
);
1495 /* When memory is not explicitely mentioned in constructor,
1496 it is 0 (or out of range). */
1497 return build_zero_cst (type
);
1500 /* CTOR is CONSTRUCTOR of an aggregate or vector.
1501 Fold reference of type TYPE and size SIZE to the memory at bit OFFSET. */
1504 fold_nonarray_ctor_reference (tree type
, tree ctor
,
1505 unsigned HOST_WIDE_INT offset
,
1506 unsigned HOST_WIDE_INT size
)
1508 unsigned HOST_WIDE_INT cnt
;
1511 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor
), cnt
, cfield
,
1514 tree byte_offset
= DECL_FIELD_OFFSET (cfield
);
1515 tree field_offset
= DECL_FIELD_BIT_OFFSET (cfield
);
1516 tree field_size
= DECL_SIZE (cfield
);
1517 double_int bitoffset
;
1518 double_int byte_offset_cst
= tree_to_double_int (byte_offset
);
1519 double_int bits_per_unit_cst
= uhwi_to_double_int (BITS_PER_UNIT
);
1520 double_int bitoffset_end
;
1522 /* Variable sized objects in static constructors makes no sense,
1523 but field_size can be NULL for flexible array members. */
1524 gcc_assert (TREE_CODE (field_offset
) == INTEGER_CST
1525 && TREE_CODE (byte_offset
) == INTEGER_CST
1526 && (field_size
!= NULL_TREE
1527 ? TREE_CODE (field_size
) == INTEGER_CST
1528 : TREE_CODE (TREE_TYPE (cfield
)) == ARRAY_TYPE
));
1530 /* Compute bit offset of the field. */
1531 bitoffset
= double_int_add (tree_to_double_int (field_offset
),
1532 double_int_mul (byte_offset_cst
,
1533 bits_per_unit_cst
));
1534 /* Compute bit offset where the field ends. */
1535 if (field_size
!= NULL_TREE
)
1536 bitoffset_end
= double_int_add (bitoffset
,
1537 tree_to_double_int (field_size
));
1539 bitoffset_end
= double_int_zero
;
1541 /* Is OFFSET in the range (BITOFFSET, BITOFFSET_END)? */
1542 if (double_int_cmp (uhwi_to_double_int (offset
), bitoffset
, 0) >= 0
1543 && (field_size
== NULL_TREE
1544 || double_int_cmp (uhwi_to_double_int (offset
),
1545 bitoffset_end
, 0) < 0))
1547 double_int access_end
= double_int_add (uhwi_to_double_int (offset
),
1548 uhwi_to_double_int (size
));
1549 double_int inner_offset
= double_int_sub (uhwi_to_double_int (offset
),
1551 /* We do have overlap. Now see if field is large enough to
1552 cover the access. Give up for accesses spanning multiple
1554 if (double_int_cmp (access_end
, bitoffset_end
, 0) > 0)
1556 return fold_ctor_reference (type
, cval
,
1557 double_int_to_uhwi (inner_offset
), size
);
1560 /* When memory is not explicitely mentioned in constructor, it is 0. */
1561 return build_zero_cst (type
);
1564 /* CTOR is value initializing memory, fold reference of type TYPE and size SIZE
1565 to the memory at bit OFFSET. */
1568 fold_ctor_reference (tree type
, tree ctor
, unsigned HOST_WIDE_INT offset
,
1569 unsigned HOST_WIDE_INT size
)
1573 /* We found the field with exact match. */
1574 if (useless_type_conversion_p (type
, TREE_TYPE (ctor
))
1576 return canonicalize_constructor_val (ctor
);
1578 /* We are at the end of walk, see if we can view convert the
1580 if (!AGGREGATE_TYPE_P (TREE_TYPE (ctor
)) && !offset
1581 /* VIEW_CONVERT_EXPR is defined only for matching sizes. */
1582 && operand_equal_p (TYPE_SIZE (type
),
1583 TYPE_SIZE (TREE_TYPE (ctor
)), 0))
1585 ret
= canonicalize_constructor_val (ctor
);
1586 ret
= fold_unary (VIEW_CONVERT_EXPR
, type
, ret
);
1591 if (TREE_CODE (ctor
) == STRING_CST
)
1592 return fold_string_cst_ctor_reference (type
, ctor
, offset
, size
);
1593 if (TREE_CODE (ctor
) == CONSTRUCTOR
)
1596 if (TREE_CODE (TREE_TYPE (ctor
)) == ARRAY_TYPE
)
1597 return fold_array_ctor_reference (type
, ctor
, offset
, size
);
1599 return fold_nonarray_ctor_reference (type
, ctor
, offset
, size
);
1605 /* Return the tree representing the element referenced by T if T is an
1606 ARRAY_REF or COMPONENT_REF into constant aggregates. Return
1607 NULL_TREE otherwise. */
1610 fold_const_aggregate_ref (tree t
)
1612 tree ctor
, idx
, base
;
1613 HOST_WIDE_INT offset
, size
, max_size
;
1616 if (TREE_CODE_CLASS (TREE_CODE (t
)) == tcc_declaration
)
1617 return get_symbol_constant_value (t
);
1619 tem
= fold_read_from_constant_string (t
);
1623 switch (TREE_CODE (t
))
1626 case ARRAY_RANGE_REF
:
1627 /* Constant indexes are handled well by get_base_constructor.
1628 Only special case variable offsets.
1629 FIXME: This code can't handle nested references with variable indexes
1630 (they will be handled only by iteration of ccp). Perhaps we can bring
1631 get_ref_base_and_extent here and make it use get_constant_value. */
1632 if (TREE_CODE (TREE_OPERAND (t
, 1)) == SSA_NAME
1633 && (idx
= get_constant_value (TREE_OPERAND (t
, 1)))
1634 && host_integerp (idx
, 0))
1636 tree low_bound
, unit_size
;
1638 /* If the resulting bit-offset is constant, track it. */
1639 if ((low_bound
= array_ref_low_bound (t
),
1640 host_integerp (low_bound
, 0))
1641 && (unit_size
= array_ref_element_size (t
),
1642 host_integerp (unit_size
, 1)))
1644 offset
= TREE_INT_CST_LOW (idx
);
1645 offset
-= TREE_INT_CST_LOW (low_bound
);
1646 offset
*= TREE_INT_CST_LOW (unit_size
);
1647 offset
*= BITS_PER_UNIT
;
1649 base
= TREE_OPERAND (t
, 0);
1650 ctor
= get_base_constructor (base
, &offset
);
1651 /* Empty constructor. Always fold to 0. */
1652 if (ctor
== error_mark_node
)
1653 return build_zero_cst (TREE_TYPE (t
));
1654 /* Out of bound array access. Value is undefined, but don't fold. */
1657 /* We can not determine ctor. */
1660 return fold_ctor_reference (TREE_TYPE (t
), ctor
, offset
,
1661 TREE_INT_CST_LOW (unit_size
)
1669 case TARGET_MEM_REF
:
1671 base
= get_ref_base_and_extent (t
, &offset
, &size
, &max_size
);
1672 ctor
= get_base_constructor (base
, &offset
);
1674 /* Empty constructor. Always fold to 0. */
1675 if (ctor
== error_mark_node
)
1676 return build_zero_cst (TREE_TYPE (t
));
1677 /* We do not know precise address. */
1678 if (max_size
== -1 || max_size
!= size
)
1680 /* We can not determine ctor. */
1684 /* Out of bound array access. Value is undefined, but don't fold. */
1688 return fold_ctor_reference (TREE_TYPE (t
), ctor
, offset
, size
);
1693 tree c
= fold_const_aggregate_ref (TREE_OPERAND (t
, 0));
1694 if (c
&& TREE_CODE (c
) == COMPLEX_CST
)
1695 return fold_build1_loc (EXPR_LOCATION (t
),
1696 TREE_CODE (t
), TREE_TYPE (t
), c
);
1707 /* Apply the operation CODE in type TYPE to the value, mask pair
1708 RVAL and RMASK representing a value of type RTYPE and set
1709 the value, mask pair *VAL and *MASK to the result. */
1712 bit_value_unop_1 (enum tree_code code
, tree type
,
1713 double_int
*val
, double_int
*mask
,
1714 tree rtype
, double_int rval
, double_int rmask
)
1720 *val
= double_int_not (rval
);
1725 double_int temv
, temm
;
1726 /* Return ~rval + 1. */
1727 bit_value_unop_1 (BIT_NOT_EXPR
, type
, &temv
, &temm
, type
, rval
, rmask
);
1728 bit_value_binop_1 (PLUS_EXPR
, type
, val
, mask
,
1730 type
, double_int_one
, double_int_zero
);
1738 /* First extend mask and value according to the original type. */
1739 uns
= (TREE_CODE (rtype
) == INTEGER_TYPE
&& TYPE_IS_SIZETYPE (rtype
)
1740 ? 0 : TYPE_UNSIGNED (rtype
));
1741 *mask
= double_int_ext (rmask
, TYPE_PRECISION (rtype
), uns
);
1742 *val
= double_int_ext (rval
, TYPE_PRECISION (rtype
), uns
);
1744 /* Then extend mask and value according to the target type. */
1745 uns
= (TREE_CODE (type
) == INTEGER_TYPE
&& TYPE_IS_SIZETYPE (type
)
1746 ? 0 : TYPE_UNSIGNED (type
));
1747 *mask
= double_int_ext (*mask
, TYPE_PRECISION (type
), uns
);
1748 *val
= double_int_ext (*val
, TYPE_PRECISION (type
), uns
);
1753 *mask
= double_int_minus_one
;
1758 /* Apply the operation CODE in type TYPE to the value, mask pairs
1759 R1VAL, R1MASK and R2VAL, R2MASK representing a values of type R1TYPE
1760 and R2TYPE and set the value, mask pair *VAL and *MASK to the result. */
1763 bit_value_binop_1 (enum tree_code code
, tree type
,
1764 double_int
*val
, double_int
*mask
,
1765 tree r1type
, double_int r1val
, double_int r1mask
,
1766 tree r2type
, double_int r2val
, double_int r2mask
)
1768 bool uns
= (TREE_CODE (type
) == INTEGER_TYPE
1769 && TYPE_IS_SIZETYPE (type
) ? 0 : TYPE_UNSIGNED (type
));
1770 /* Assume we'll get a constant result. Use an initial varying value,
1771 we fall back to varying in the end if necessary. */
1772 *mask
= double_int_minus_one
;
1776 /* The mask is constant where there is a known not
1777 set bit, (m1 | m2) & ((v1 | m1) & (v2 | m2)) */
1778 *mask
= double_int_and (double_int_ior (r1mask
, r2mask
),
1779 double_int_and (double_int_ior (r1val
, r1mask
),
1780 double_int_ior (r2val
, r2mask
)));
1781 *val
= double_int_and (r1val
, r2val
);
1785 /* The mask is constant where there is a known
1786 set bit, (m1 | m2) & ~((v1 & ~m1) | (v2 & ~m2)). */
1787 *mask
= double_int_and_not
1788 (double_int_ior (r1mask
, r2mask
),
1789 double_int_ior (double_int_and_not (r1val
, r1mask
),
1790 double_int_and_not (r2val
, r2mask
)));
1791 *val
= double_int_ior (r1val
, r2val
);
1796 *mask
= double_int_ior (r1mask
, r2mask
);
1797 *val
= double_int_xor (r1val
, r2val
);
1802 if (double_int_zero_p (r2mask
))
1804 HOST_WIDE_INT shift
= r2val
.low
;
1805 if (code
== RROTATE_EXPR
)
1807 *mask
= double_int_lrotate (r1mask
, shift
, TYPE_PRECISION (type
));
1808 *val
= double_int_lrotate (r1val
, shift
, TYPE_PRECISION (type
));
1814 /* ??? We can handle partially known shift counts if we know
1815 its sign. That way we can tell that (x << (y | 8)) & 255
1817 if (double_int_zero_p (r2mask
))
1819 HOST_WIDE_INT shift
= r2val
.low
;
1820 if (code
== RSHIFT_EXPR
)
1822 /* We need to know if we are doing a left or a right shift
1823 to properly shift in zeros for left shift and unsigned
1824 right shifts and the sign bit for signed right shifts.
1825 For signed right shifts we shift in varying in case
1826 the sign bit was varying. */
1829 *mask
= double_int_lshift (r1mask
, shift
,
1830 TYPE_PRECISION (type
), false);
1831 *val
= double_int_lshift (r1val
, shift
,
1832 TYPE_PRECISION (type
), false);
1837 *mask
= double_int_rshift (r1mask
, shift
,
1838 TYPE_PRECISION (type
), !uns
);
1839 *val
= double_int_rshift (r1val
, shift
,
1840 TYPE_PRECISION (type
), !uns
);
1851 case POINTER_PLUS_EXPR
:
1854 /* Do the addition with unknown bits set to zero, to give carry-ins of
1855 zero wherever possible. */
1856 lo
= double_int_add (double_int_and_not (r1val
, r1mask
),
1857 double_int_and_not (r2val
, r2mask
));
1858 lo
= double_int_ext (lo
, TYPE_PRECISION (type
), uns
);
1859 /* Do the addition with unknown bits set to one, to give carry-ins of
1860 one wherever possible. */
1861 hi
= double_int_add (double_int_ior (r1val
, r1mask
),
1862 double_int_ior (r2val
, r2mask
));
1863 hi
= double_int_ext (hi
, TYPE_PRECISION (type
), uns
);
1864 /* Each bit in the result is known if (a) the corresponding bits in
1865 both inputs are known, and (b) the carry-in to that bit position
1866 is known. We can check condition (b) by seeing if we got the same
1867 result with minimised carries as with maximised carries. */
1868 *mask
= double_int_ior (double_int_ior (r1mask
, r2mask
),
1869 double_int_xor (lo
, hi
));
1870 *mask
= double_int_ext (*mask
, TYPE_PRECISION (type
), uns
);
1871 /* It shouldn't matter whether we choose lo or hi here. */
1878 double_int temv
, temm
;
1879 bit_value_unop_1 (NEGATE_EXPR
, r2type
, &temv
, &temm
,
1880 r2type
, r2val
, r2mask
);
1881 bit_value_binop_1 (PLUS_EXPR
, type
, val
, mask
,
1882 r1type
, r1val
, r1mask
,
1883 r2type
, temv
, temm
);
1889 /* Just track trailing zeros in both operands and transfer
1890 them to the other. */
1891 int r1tz
= double_int_ctz (double_int_ior (r1val
, r1mask
));
1892 int r2tz
= double_int_ctz (double_int_ior (r2val
, r2mask
));
1893 if (r1tz
+ r2tz
>= HOST_BITS_PER_DOUBLE_INT
)
1895 *mask
= double_int_zero
;
1896 *val
= double_int_zero
;
1898 else if (r1tz
+ r2tz
> 0)
1900 *mask
= double_int_not (double_int_mask (r1tz
+ r2tz
));
1901 *mask
= double_int_ext (*mask
, TYPE_PRECISION (type
), uns
);
1902 *val
= double_int_zero
;
1910 double_int m
= double_int_ior (r1mask
, r2mask
);
1911 if (!double_int_equal_p (double_int_and_not (r1val
, m
),
1912 double_int_and_not (r2val
, m
)))
1914 *mask
= double_int_zero
;
1915 *val
= ((code
== EQ_EXPR
) ? double_int_zero
: double_int_one
);
1919 /* We know the result of a comparison is always one or zero. */
1920 *mask
= double_int_one
;
1921 *val
= double_int_zero
;
1929 double_int tem
= r1val
;
1935 code
= swap_tree_comparison (code
);
1942 /* If the most significant bits are not known we know nothing. */
1943 if (double_int_negative_p (r1mask
) || double_int_negative_p (r2mask
))
1946 /* If we know the most significant bits we know the values
1947 value ranges by means of treating varying bits as zero
1948 or one. Do a cross comparison of the max/min pairs. */
1949 maxmin
= double_int_cmp (double_int_ior (r1val
, r1mask
),
1950 double_int_and_not (r2val
, r2mask
), uns
);
1951 minmax
= double_int_cmp (double_int_and_not (r1val
, r1mask
),
1952 double_int_ior (r2val
, r2mask
), uns
);
1953 if (maxmin
< 0) /* r1 is less than r2. */
1955 *mask
= double_int_zero
;
1956 *val
= double_int_one
;
1958 else if (minmax
> 0) /* r1 is not less or equal to r2. */
1960 *mask
= double_int_zero
;
1961 *val
= double_int_zero
;
1963 else if (maxmin
== minmax
) /* r1 and r2 are equal. */
1965 /* This probably should never happen as we'd have
1966 folded the thing during fully constant value folding. */
1967 *mask
= double_int_zero
;
1968 *val
= (code
== LE_EXPR
? double_int_one
: double_int_zero
);
1972 /* We know the result of a comparison is always one or zero. */
1973 *mask
= double_int_one
;
1974 *val
= double_int_zero
;
1983 /* Return the propagation value when applying the operation CODE to
1984 the value RHS yielding type TYPE. */
1987 bit_value_unop (enum tree_code code
, tree type
, tree rhs
)
1989 prop_value_t rval
= get_value_for_expr (rhs
, true);
1990 double_int value
, mask
;
1992 gcc_assert ((rval
.lattice_val
== CONSTANT
1993 && TREE_CODE (rval
.value
) == INTEGER_CST
)
1994 || double_int_minus_one_p (rval
.mask
));
1995 bit_value_unop_1 (code
, type
, &value
, &mask
,
1996 TREE_TYPE (rhs
), value_to_double_int (rval
), rval
.mask
);
1997 if (!double_int_minus_one_p (mask
))
1999 val
.lattice_val
= CONSTANT
;
2001 /* ??? Delay building trees here. */
2002 val
.value
= double_int_to_tree (type
, value
);
2006 val
.lattice_val
= VARYING
;
2007 val
.value
= NULL_TREE
;
2008 val
.mask
= double_int_minus_one
;
2013 /* Return the propagation value when applying the operation CODE to
2014 the values RHS1 and RHS2 yielding type TYPE. */
2017 bit_value_binop (enum tree_code code
, tree type
, tree rhs1
, tree rhs2
)
2019 prop_value_t r1val
= get_value_for_expr (rhs1
, true);
2020 prop_value_t r2val
= get_value_for_expr (rhs2
, true);
2021 double_int value
, mask
;
2023 gcc_assert ((r1val
.lattice_val
== CONSTANT
2024 && TREE_CODE (r1val
.value
) == INTEGER_CST
)
2025 || double_int_minus_one_p (r1val
.mask
));
2026 gcc_assert ((r2val
.lattice_val
== CONSTANT
2027 && TREE_CODE (r2val
.value
) == INTEGER_CST
)
2028 || double_int_minus_one_p (r2val
.mask
));
2029 bit_value_binop_1 (code
, type
, &value
, &mask
,
2030 TREE_TYPE (rhs1
), value_to_double_int (r1val
), r1val
.mask
,
2031 TREE_TYPE (rhs2
), value_to_double_int (r2val
), r2val
.mask
);
2032 if (!double_int_minus_one_p (mask
))
2034 val
.lattice_val
= CONSTANT
;
2036 /* ??? Delay building trees here. */
2037 val
.value
= double_int_to_tree (type
, value
);
2041 val
.lattice_val
= VARYING
;
2042 val
.value
= NULL_TREE
;
2043 val
.mask
= double_int_minus_one
;
2048 /* Evaluate statement STMT.
2049 Valid only for assignments, calls, conditionals, and switches. */
2052 evaluate_stmt (gimple stmt
)
2055 tree simplified
= NULL_TREE
;
2056 ccp_lattice_t likelyvalue
= likely_value (stmt
);
2057 bool is_constant
= false;
2059 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2061 fprintf (dump_file
, "which is likely ");
2062 switch (likelyvalue
)
2065 fprintf (dump_file
, "CONSTANT");
2068 fprintf (dump_file
, "UNDEFINED");
2071 fprintf (dump_file
, "VARYING");
2075 fprintf (dump_file
, "\n");
2078 /* If the statement is likely to have a CONSTANT result, then try
2079 to fold the statement to determine the constant value. */
2080 /* FIXME. This is the only place that we call ccp_fold.
2081 Since likely_value never returns CONSTANT for calls, we will
2082 not attempt to fold them, including builtins that may profit. */
2083 if (likelyvalue
== CONSTANT
)
2085 fold_defer_overflow_warnings ();
2086 simplified
= ccp_fold (stmt
);
2087 is_constant
= simplified
&& is_gimple_min_invariant (simplified
);
2088 fold_undefer_overflow_warnings (is_constant
, stmt
, 0);
2091 /* The statement produced a constant value. */
2092 val
.lattice_val
= CONSTANT
;
2093 val
.value
= simplified
;
2094 val
.mask
= double_int_zero
;
2097 /* If the statement is likely to have a VARYING result, then do not
2098 bother folding the statement. */
2099 else if (likelyvalue
== VARYING
)
2101 enum gimple_code code
= gimple_code (stmt
);
2102 if (code
== GIMPLE_ASSIGN
)
2104 enum tree_code subcode
= gimple_assign_rhs_code (stmt
);
2106 /* Other cases cannot satisfy is_gimple_min_invariant
2108 if (get_gimple_rhs_class (subcode
) == GIMPLE_SINGLE_RHS
)
2109 simplified
= gimple_assign_rhs1 (stmt
);
2111 else if (code
== GIMPLE_SWITCH
)
2112 simplified
= gimple_switch_index (stmt
);
2114 /* These cannot satisfy is_gimple_min_invariant without folding. */
2115 gcc_assert (code
== GIMPLE_CALL
|| code
== GIMPLE_COND
);
2116 is_constant
= simplified
&& is_gimple_min_invariant (simplified
);
2119 /* The statement produced a constant value. */
2120 val
.lattice_val
= CONSTANT
;
2121 val
.value
= simplified
;
2122 val
.mask
= double_int_zero
;
2126 /* Resort to simplification for bitwise tracking. */
2127 if (flag_tree_bit_ccp
2128 && likelyvalue
== CONSTANT
2131 enum gimple_code code
= gimple_code (stmt
);
2133 val
.lattice_val
= VARYING
;
2134 val
.value
= NULL_TREE
;
2135 val
.mask
= double_int_minus_one
;
2136 if (code
== GIMPLE_ASSIGN
)
2138 enum tree_code subcode
= gimple_assign_rhs_code (stmt
);
2139 tree rhs1
= gimple_assign_rhs1 (stmt
);
2140 switch (get_gimple_rhs_class (subcode
))
2142 case GIMPLE_SINGLE_RHS
:
2143 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
2144 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
2145 val
= get_value_for_expr (rhs1
, true);
2148 case GIMPLE_UNARY_RHS
:
2149 if ((INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
2150 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
2151 && (INTEGRAL_TYPE_P (gimple_expr_type (stmt
))
2152 || POINTER_TYPE_P (gimple_expr_type (stmt
))))
2153 val
= bit_value_unop (subcode
, gimple_expr_type (stmt
), rhs1
);
2156 case GIMPLE_BINARY_RHS
:
2157 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
2158 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
2160 tree rhs2
= gimple_assign_rhs2 (stmt
);
2161 val
= bit_value_binop (subcode
,
2162 TREE_TYPE (rhs1
), rhs1
, rhs2
);
2169 else if (code
== GIMPLE_COND
)
2171 enum tree_code code
= gimple_cond_code (stmt
);
2172 tree rhs1
= gimple_cond_lhs (stmt
);
2173 tree rhs2
= gimple_cond_rhs (stmt
);
2174 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
2175 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
2176 val
= bit_value_binop (code
, TREE_TYPE (rhs1
), rhs1
, rhs2
);
2178 else if (code
== GIMPLE_CALL
2179 && (fndecl
= gimple_call_fndecl (stmt
))
2180 && DECL_BUILT_IN_CLASS (fndecl
) == BUILT_IN_NORMAL
)
2182 switch (DECL_FUNCTION_CODE (fndecl
))
2184 case BUILT_IN_MALLOC
:
2185 case BUILT_IN_REALLOC
:
2186 case BUILT_IN_CALLOC
:
2187 val
.lattice_val
= CONSTANT
;
2188 val
.value
= build_int_cst (TREE_TYPE (gimple_get_lhs (stmt
)), 0);
2189 val
.mask
= shwi_to_double_int
2190 (~(((HOST_WIDE_INT
) MALLOC_ABI_ALIGNMENT
)
2191 / BITS_PER_UNIT
- 1));
2194 case BUILT_IN_ALLOCA
:
2195 val
.lattice_val
= CONSTANT
;
2196 val
.value
= build_int_cst (TREE_TYPE (gimple_get_lhs (stmt
)), 0);
2197 val
.mask
= shwi_to_double_int
2198 (~(((HOST_WIDE_INT
) BIGGEST_ALIGNMENT
)
2199 / BITS_PER_UNIT
- 1));
2205 is_constant
= (val
.lattice_val
== CONSTANT
);
2210 /* The statement produced a nonconstant value. If the statement
2211 had UNDEFINED operands, then the result of the statement
2212 should be UNDEFINED. Otherwise, the statement is VARYING. */
2213 if (likelyvalue
== UNDEFINED
)
2215 val
.lattice_val
= likelyvalue
;
2216 val
.mask
= double_int_zero
;
2220 val
.lattice_val
= VARYING
;
2221 val
.mask
= double_int_minus_one
;
2224 val
.value
= NULL_TREE
;
2230 /* Fold the stmt at *GSI with CCP specific information that propagating
2231 and regular folding does not catch. */
2234 ccp_fold_stmt (gimple_stmt_iterator
*gsi
)
2236 gimple stmt
= gsi_stmt (*gsi
);
2238 switch (gimple_code (stmt
))
2243 /* Statement evaluation will handle type mismatches in constants
2244 more gracefully than the final propagation. This allows us to
2245 fold more conditionals here. */
2246 val
= evaluate_stmt (stmt
);
2247 if (val
.lattice_val
!= CONSTANT
2248 || !double_int_zero_p (val
.mask
))
2253 fprintf (dump_file
, "Folding predicate ");
2254 print_gimple_expr (dump_file
, stmt
, 0, 0);
2255 fprintf (dump_file
, " to ");
2256 print_generic_expr (dump_file
, val
.value
, 0);
2257 fprintf (dump_file
, "\n");
2260 if (integer_zerop (val
.value
))
2261 gimple_cond_make_false (stmt
);
2263 gimple_cond_make_true (stmt
);
2270 tree lhs
= gimple_call_lhs (stmt
);
2274 bool changed
= false;
2277 /* If the call was folded into a constant make sure it goes
2278 away even if we cannot propagate into all uses because of
2281 && TREE_CODE (lhs
) == SSA_NAME
2282 && (val
= get_constant_value (lhs
)))
2284 tree new_rhs
= unshare_expr (val
);
2286 if (!useless_type_conversion_p (TREE_TYPE (lhs
),
2287 TREE_TYPE (new_rhs
)))
2288 new_rhs
= fold_convert (TREE_TYPE (lhs
), new_rhs
);
2289 res
= update_call_from_tree (gsi
, new_rhs
);
2294 /* Propagate into the call arguments. Compared to replace_uses_in
2295 this can use the argument slot types for type verification
2296 instead of the current argument type. We also can safely
2297 drop qualifiers here as we are dealing with constants anyway. */
2298 argt
= TYPE_ARG_TYPES (TREE_TYPE (TREE_TYPE (gimple_call_fn (stmt
))));
2299 for (i
= 0; i
< gimple_call_num_args (stmt
) && argt
;
2300 ++i
, argt
= TREE_CHAIN (argt
))
2302 tree arg
= gimple_call_arg (stmt
, i
);
2303 if (TREE_CODE (arg
) == SSA_NAME
2304 && (val
= get_constant_value (arg
))
2305 && useless_type_conversion_p
2306 (TYPE_MAIN_VARIANT (TREE_VALUE (argt
)),
2307 TYPE_MAIN_VARIANT (TREE_TYPE (val
))))
2309 gimple_call_set_arg (stmt
, i
, unshare_expr (val
));
2314 callee
= gimple_call_fn (stmt
);
2315 if (TREE_CODE (callee
) == OBJ_TYPE_REF
2316 && TREE_CODE (OBJ_TYPE_REF_EXPR (callee
)) == SSA_NAME
)
2318 tree expr
= OBJ_TYPE_REF_EXPR (callee
);
2319 OBJ_TYPE_REF_EXPR (callee
) = valueize_op (expr
);
2320 if (TREE_CODE (OBJ_TYPE_REF_EXPR (callee
)) == ADDR_EXPR
)
2323 t
= gimple_fold_obj_type_ref (callee
, NULL_TREE
);
2326 gimple_call_set_fn (stmt
, t
);
2330 OBJ_TYPE_REF_EXPR (callee
) = expr
;
2338 tree lhs
= gimple_assign_lhs (stmt
);
2341 /* If we have a load that turned out to be constant replace it
2342 as we cannot propagate into all uses in all cases. */
2343 if (gimple_assign_single_p (stmt
)
2344 && TREE_CODE (lhs
) == SSA_NAME
2345 && (val
= get_constant_value (lhs
)))
2347 tree rhs
= unshare_expr (val
);
2348 if (!useless_type_conversion_p (TREE_TYPE (lhs
), TREE_TYPE (rhs
)))
2349 rhs
= fold_build1 (VIEW_CONVERT_EXPR
, TREE_TYPE (lhs
), rhs
);
2350 gimple_assign_set_rhs_from_tree (gsi
, rhs
);
2362 /* Visit the assignment statement STMT. Set the value of its LHS to the
2363 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
2364 creates virtual definitions, set the value of each new name to that
2365 of the RHS (if we can derive a constant out of the RHS).
2366 Value-returning call statements also perform an assignment, and
2367 are handled here. */
2369 static enum ssa_prop_result
2370 visit_assignment (gimple stmt
, tree
*output_p
)
2373 enum ssa_prop_result retval
;
2375 tree lhs
= gimple_get_lhs (stmt
);
2377 gcc_assert (gimple_code (stmt
) != GIMPLE_CALL
2378 || gimple_call_lhs (stmt
) != NULL_TREE
);
2380 if (gimple_assign_single_p (stmt
)
2381 && gimple_assign_rhs_code (stmt
) == SSA_NAME
)
2382 /* For a simple copy operation, we copy the lattice values. */
2383 val
= *get_value (gimple_assign_rhs1 (stmt
));
2385 /* Evaluate the statement, which could be
2386 either a GIMPLE_ASSIGN or a GIMPLE_CALL. */
2387 val
= evaluate_stmt (stmt
);
2389 retval
= SSA_PROP_NOT_INTERESTING
;
2391 /* Set the lattice value of the statement's output. */
2392 if (TREE_CODE (lhs
) == SSA_NAME
)
2394 /* If STMT is an assignment to an SSA_NAME, we only have one
2396 if (set_lattice_value (lhs
, val
))
2399 if (val
.lattice_val
== VARYING
)
2400 retval
= SSA_PROP_VARYING
;
2402 retval
= SSA_PROP_INTERESTING
;
2410 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
2411 if it can determine which edge will be taken. Otherwise, return
2412 SSA_PROP_VARYING. */
2414 static enum ssa_prop_result
2415 visit_cond_stmt (gimple stmt
, edge
*taken_edge_p
)
2420 block
= gimple_bb (stmt
);
2421 val
= evaluate_stmt (stmt
);
2422 if (val
.lattice_val
!= CONSTANT
2423 || !double_int_zero_p (val
.mask
))
2424 return SSA_PROP_VARYING
;
2426 /* Find which edge out of the conditional block will be taken and add it
2427 to the worklist. If no single edge can be determined statically,
2428 return SSA_PROP_VARYING to feed all the outgoing edges to the
2429 propagation engine. */
2430 *taken_edge_p
= find_taken_edge (block
, val
.value
);
2432 return SSA_PROP_INTERESTING
;
2434 return SSA_PROP_VARYING
;
2438 /* Evaluate statement STMT. If the statement produces an output value and
2439 its evaluation changes the lattice value of its output, return
2440 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
2443 If STMT is a conditional branch and we can determine its truth
2444 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
2445 value, return SSA_PROP_VARYING. */
2447 static enum ssa_prop_result
2448 ccp_visit_stmt (gimple stmt
, edge
*taken_edge_p
, tree
*output_p
)
2453 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2455 fprintf (dump_file
, "\nVisiting statement:\n");
2456 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2459 switch (gimple_code (stmt
))
2462 /* If the statement is an assignment that produces a single
2463 output value, evaluate its RHS to see if the lattice value of
2464 its output has changed. */
2465 return visit_assignment (stmt
, output_p
);
2468 /* A value-returning call also performs an assignment. */
2469 if (gimple_call_lhs (stmt
) != NULL_TREE
)
2470 return visit_assignment (stmt
, output_p
);
2475 /* If STMT is a conditional branch, see if we can determine
2476 which branch will be taken. */
2477 /* FIXME. It appears that we should be able to optimize
2478 computed GOTOs here as well. */
2479 return visit_cond_stmt (stmt
, taken_edge_p
);
2485 /* Any other kind of statement is not interesting for constant
2486 propagation and, therefore, not worth simulating. */
2487 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2488 fprintf (dump_file
, "No interesting values produced. Marked VARYING.\n");
2490 /* Definitions made by statements other than assignments to
2491 SSA_NAMEs represent unknown modifications to their outputs.
2492 Mark them VARYING. */
2493 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
2495 prop_value_t v
= { VARYING
, NULL_TREE
, { -1, (HOST_WIDE_INT
) -1 } };
2496 set_lattice_value (def
, v
);
2499 return SSA_PROP_VARYING
;
2503 /* Main entry point for SSA Conditional Constant Propagation. */
2509 ssa_propagate (ccp_visit_stmt
, ccp_visit_phi_node
);
2510 if (ccp_finalize ())
2511 return (TODO_cleanup_cfg
| TODO_update_ssa
| TODO_remove_unused_locals
);
2520 return flag_tree_ccp
!= 0;
2524 struct gimple_opt_pass pass_ccp
=
2529 gate_ccp
, /* gate */
2530 do_ssa_ccp
, /* execute */
2533 0, /* static_pass_number */
2534 TV_TREE_CCP
, /* tv_id */
2535 PROP_cfg
| PROP_ssa
, /* properties_required */
2536 0, /* properties_provided */
2537 0, /* properties_destroyed */
2538 0, /* todo_flags_start */
2539 TODO_dump_func
| TODO_verify_ssa
2540 | TODO_verify_stmts
| TODO_ggc_collect
/* todo_flags_finish */
2546 /* Try to optimize out __builtin_stack_restore. Optimize it out
2547 if there is another __builtin_stack_restore in the same basic
2548 block and no calls or ASM_EXPRs are in between, or if this block's
2549 only outgoing edge is to EXIT_BLOCK and there are no calls or
2550 ASM_EXPRs after this __builtin_stack_restore. */
2553 optimize_stack_restore (gimple_stmt_iterator i
)
2558 basic_block bb
= gsi_bb (i
);
2559 gimple call
= gsi_stmt (i
);
2561 if (gimple_code (call
) != GIMPLE_CALL
2562 || gimple_call_num_args (call
) != 1
2563 || TREE_CODE (gimple_call_arg (call
, 0)) != SSA_NAME
2564 || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call
, 0))))
2567 for (gsi_next (&i
); !gsi_end_p (i
); gsi_next (&i
))
2569 stmt
= gsi_stmt (i
);
2570 if (gimple_code (stmt
) == GIMPLE_ASM
)
2572 if (gimple_code (stmt
) != GIMPLE_CALL
)
2575 callee
= gimple_call_fndecl (stmt
);
2577 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2578 /* All regular builtins are ok, just obviously not alloca. */
2579 || DECL_FUNCTION_CODE (callee
) == BUILT_IN_ALLOCA
)
2582 if (DECL_FUNCTION_CODE (callee
) == BUILT_IN_STACK_RESTORE
)
2583 goto second_stack_restore
;
2589 /* Allow one successor of the exit block, or zero successors. */
2590 switch (EDGE_COUNT (bb
->succs
))
2595 if (single_succ_edge (bb
)->dest
!= EXIT_BLOCK_PTR
)
2601 second_stack_restore
:
2603 /* If there's exactly one use, then zap the call to __builtin_stack_save.
2604 If there are multiple uses, then the last one should remove the call.
2605 In any case, whether the call to __builtin_stack_save can be removed
2606 or not is irrelevant to removing the call to __builtin_stack_restore. */
2607 if (has_single_use (gimple_call_arg (call
, 0)))
2609 gimple stack_save
= SSA_NAME_DEF_STMT (gimple_call_arg (call
, 0));
2610 if (is_gimple_call (stack_save
))
2612 callee
= gimple_call_fndecl (stack_save
);
2614 && DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
2615 && DECL_FUNCTION_CODE (callee
) == BUILT_IN_STACK_SAVE
)
2617 gimple_stmt_iterator stack_save_gsi
;
2620 stack_save_gsi
= gsi_for_stmt (stack_save
);
2621 rhs
= build_int_cst (TREE_TYPE (gimple_call_arg (call
, 0)), 0);
2622 update_call_from_tree (&stack_save_gsi
, rhs
);
2627 /* No effect, so the statement will be deleted. */
2628 return integer_zero_node
;
2631 /* If va_list type is a simple pointer and nothing special is needed,
2632 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
2633 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
2634 pointer assignment. */
2637 optimize_stdarg_builtin (gimple call
)
2639 tree callee
, lhs
, rhs
, cfun_va_list
;
2640 bool va_list_simple_ptr
;
2641 location_t loc
= gimple_location (call
);
2643 if (gimple_code (call
) != GIMPLE_CALL
)
2646 callee
= gimple_call_fndecl (call
);
2648 cfun_va_list
= targetm
.fn_abi_va_list (callee
);
2649 va_list_simple_ptr
= POINTER_TYPE_P (cfun_va_list
)
2650 && (TREE_TYPE (cfun_va_list
) == void_type_node
2651 || TREE_TYPE (cfun_va_list
) == char_type_node
);
2653 switch (DECL_FUNCTION_CODE (callee
))
2655 case BUILT_IN_VA_START
:
2656 if (!va_list_simple_ptr
2657 || targetm
.expand_builtin_va_start
!= NULL
2658 || built_in_decls
[BUILT_IN_NEXT_ARG
] == NULL
)
2661 if (gimple_call_num_args (call
) != 2)
2664 lhs
= gimple_call_arg (call
, 0);
2665 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2666 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2667 != TYPE_MAIN_VARIANT (cfun_va_list
))
2670 lhs
= build_fold_indirect_ref_loc (loc
, lhs
);
2671 rhs
= build_call_expr_loc (loc
, built_in_decls
[BUILT_IN_NEXT_ARG
],
2672 1, integer_zero_node
);
2673 rhs
= fold_convert_loc (loc
, TREE_TYPE (lhs
), rhs
);
2674 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2676 case BUILT_IN_VA_COPY
:
2677 if (!va_list_simple_ptr
)
2680 if (gimple_call_num_args (call
) != 2)
2683 lhs
= gimple_call_arg (call
, 0);
2684 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2685 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2686 != TYPE_MAIN_VARIANT (cfun_va_list
))
2689 lhs
= build_fold_indirect_ref_loc (loc
, lhs
);
2690 rhs
= gimple_call_arg (call
, 1);
2691 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs
))
2692 != TYPE_MAIN_VARIANT (cfun_va_list
))
2695 rhs
= fold_convert_loc (loc
, TREE_TYPE (lhs
), rhs
);
2696 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2698 case BUILT_IN_VA_END
:
2699 /* No effect, so the statement will be deleted. */
2700 return integer_zero_node
;
2707 /* A simple pass that attempts to fold all builtin functions. This pass
2708 is run after we've propagated as many constants as we can. */
2711 execute_fold_all_builtins (void)
2713 bool cfg_changed
= false;
2715 unsigned int todoflags
= 0;
2719 gimple_stmt_iterator i
;
2720 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); )
2722 gimple stmt
, old_stmt
;
2723 tree callee
, result
;
2724 enum built_in_function fcode
;
2726 stmt
= gsi_stmt (i
);
2728 if (gimple_code (stmt
) != GIMPLE_CALL
)
2733 callee
= gimple_call_fndecl (stmt
);
2734 if (!callee
|| DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
)
2739 fcode
= DECL_FUNCTION_CODE (callee
);
2741 result
= gimple_fold_builtin (stmt
);
2744 gimple_remove_stmt_histograms (cfun
, stmt
);
2747 switch (DECL_FUNCTION_CODE (callee
))
2749 case BUILT_IN_CONSTANT_P
:
2750 /* Resolve __builtin_constant_p. If it hasn't been
2751 folded to integer_one_node by now, it's fairly
2752 certain that the value simply isn't constant. */
2753 result
= integer_zero_node
;
2756 case BUILT_IN_STACK_RESTORE
:
2757 result
= optimize_stack_restore (i
);
2763 case BUILT_IN_VA_START
:
2764 case BUILT_IN_VA_END
:
2765 case BUILT_IN_VA_COPY
:
2766 /* These shouldn't be folded before pass_stdarg. */
2767 result
= optimize_stdarg_builtin (stmt
);
2777 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2779 fprintf (dump_file
, "Simplified\n ");
2780 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2784 if (!update_call_from_tree (&i
, result
))
2786 gimplify_and_update_call_from_tree (&i
, result
);
2787 todoflags
|= TODO_update_address_taken
;
2790 stmt
= gsi_stmt (i
);
2793 if (maybe_clean_or_replace_eh_stmt (old_stmt
, stmt
)
2794 && gimple_purge_dead_eh_edges (bb
))
2797 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2799 fprintf (dump_file
, "to\n ");
2800 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2801 fprintf (dump_file
, "\n");
2804 /* Retry the same statement if it changed into another
2805 builtin, there might be new opportunities now. */
2806 if (gimple_code (stmt
) != GIMPLE_CALL
)
2811 callee
= gimple_call_fndecl (stmt
);
2813 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2814 || DECL_FUNCTION_CODE (callee
) == fcode
)
2819 /* Delete unreachable blocks. */
2821 todoflags
|= TODO_cleanup_cfg
;
2827 struct gimple_opt_pass pass_fold_builtins
=
2833 execute_fold_all_builtins
, /* execute */
2836 0, /* static_pass_number */
2837 TV_NONE
, /* tv_id */
2838 PROP_cfg
| PROP_ssa
, /* properties_required */
2839 0, /* properties_provided */
2840 0, /* properties_destroyed */
2841 0, /* todo_flags_start */
2844 | TODO_update_ssa
/* todo_flags_finish */