1 /* Conditional constant propagation pass for the GNU compiler.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
3 2010, 2011, 2012 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"
121 #include "function.h"
122 #include "gimple-pretty-print.h"
123 #include "tree-flow.h"
124 #include "tree-pass.h"
125 #include "tree-ssa-propagate.h"
126 #include "value-prof.h"
127 #include "langhooks.h"
129 #include "diagnostic-core.h"
131 #include "gimple-fold.h"
135 /* Possible lattice values. */
144 struct prop_value_d
{
146 ccp_lattice_t lattice_val
;
148 /* Propagated value. */
151 /* Mask that applies to the propagated value during CCP. For
152 X with a CONSTANT lattice value X & ~mask == value & ~mask. */
156 typedef struct prop_value_d prop_value_t
;
158 /* Array of propagated constant values. After propagation,
159 CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If
160 the constant is held in an SSA name representing a memory store
161 (i.e., a VDEF), CONST_VAL[I].MEM_REF will contain the actual
162 memory reference used to store (i.e., the LHS of the assignment
164 static prop_value_t
*const_val
;
166 static void canonicalize_float_value (prop_value_t
*);
167 static bool ccp_fold_stmt (gimple_stmt_iterator
*);
169 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */
172 dump_lattice_value (FILE *outf
, const char *prefix
, prop_value_t val
)
174 switch (val
.lattice_val
)
177 fprintf (outf
, "%sUNINITIALIZED", prefix
);
180 fprintf (outf
, "%sUNDEFINED", prefix
);
183 fprintf (outf
, "%sVARYING", prefix
);
186 fprintf (outf
, "%sCONSTANT ", prefix
);
187 if (TREE_CODE (val
.value
) != INTEGER_CST
188 || double_int_zero_p (val
.mask
))
189 print_generic_expr (outf
, val
.value
, dump_flags
);
192 double_int cval
= double_int_and_not (tree_to_double_int (val
.value
),
194 fprintf (outf
, "%sCONSTANT " HOST_WIDE_INT_PRINT_DOUBLE_HEX
,
195 prefix
, cval
.high
, cval
.low
);
196 fprintf (outf
, " (" HOST_WIDE_INT_PRINT_DOUBLE_HEX
")",
197 val
.mask
.high
, val
.mask
.low
);
206 /* Print lattice value VAL to stderr. */
208 void debug_lattice_value (prop_value_t val
);
211 debug_lattice_value (prop_value_t val
)
213 dump_lattice_value (stderr
, "", val
);
214 fprintf (stderr
, "\n");
218 /* Compute a default value for variable VAR and store it in the
219 CONST_VAL array. The following rules are used to get default
222 1- Global and static variables that are declared constant are
225 2- Any other value is considered UNDEFINED. This is useful when
226 considering PHI nodes. PHI arguments that are undefined do not
227 change the constant value of the PHI node, which allows for more
228 constants to be propagated.
230 3- Variables defined by statements other than assignments and PHI
231 nodes are considered VARYING.
233 4- Initial values of variables that are not GIMPLE registers are
234 considered VARYING. */
237 get_default_value (tree var
)
239 prop_value_t val
= { UNINITIALIZED
, NULL_TREE
, { 0, 0 } };
242 stmt
= SSA_NAME_DEF_STMT (var
);
244 if (gimple_nop_p (stmt
))
246 /* Variables defined by an empty statement are those used
247 before being initialized. If VAR is a local variable, we
248 can assume initially that it is UNDEFINED, otherwise we must
249 consider it VARYING. */
250 if (!virtual_operand_p (var
)
251 && TREE_CODE (SSA_NAME_VAR (var
)) == VAR_DECL
)
252 val
.lattice_val
= UNDEFINED
;
255 val
.lattice_val
= VARYING
;
256 val
.mask
= double_int_minus_one
;
259 else if (is_gimple_assign (stmt
)
260 /* Value-returning GIMPLE_CALL statements assign to
261 a variable, and are treated similarly to GIMPLE_ASSIGN. */
262 || (is_gimple_call (stmt
)
263 && gimple_call_lhs (stmt
) != NULL_TREE
)
264 || gimple_code (stmt
) == GIMPLE_PHI
)
267 if (gimple_assign_single_p (stmt
)
268 && DECL_P (gimple_assign_rhs1 (stmt
))
269 && (cst
= get_symbol_constant_value (gimple_assign_rhs1 (stmt
))))
271 val
.lattice_val
= CONSTANT
;
275 /* Any other variable defined by an assignment or a PHI node
276 is considered UNDEFINED. */
277 val
.lattice_val
= UNDEFINED
;
281 /* Otherwise, VAR will never take on a constant value. */
282 val
.lattice_val
= VARYING
;
283 val
.mask
= double_int_minus_one
;
290 /* Get the constant value associated with variable VAR. */
292 static inline prop_value_t
*
297 if (const_val
== NULL
)
300 val
= &const_val
[SSA_NAME_VERSION (var
)];
301 if (val
->lattice_val
== UNINITIALIZED
)
302 *val
= get_default_value (var
);
304 canonicalize_float_value (val
);
309 /* Return the constant tree value associated with VAR. */
312 get_constant_value (tree var
)
315 if (TREE_CODE (var
) != SSA_NAME
)
317 if (is_gimple_min_invariant (var
))
321 val
= get_value (var
);
323 && val
->lattice_val
== CONSTANT
324 && (TREE_CODE (val
->value
) != INTEGER_CST
325 || double_int_zero_p (val
->mask
)))
330 /* Sets the value associated with VAR to VARYING. */
333 set_value_varying (tree var
)
335 prop_value_t
*val
= &const_val
[SSA_NAME_VERSION (var
)];
337 val
->lattice_val
= VARYING
;
338 val
->value
= NULL_TREE
;
339 val
->mask
= double_int_minus_one
;
342 /* For float types, modify the value of VAL to make ccp work correctly
343 for non-standard values (-0, NaN):
345 If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0.
346 If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED.
347 This is to fix the following problem (see PR 29921): Suppose we have
351 and we set value of y to NaN. This causes value of x to be set to NaN.
352 When we later determine that y is in fact VARYING, fold uses the fact
353 that HONOR_NANS is false, and we try to change the value of x to 0,
354 causing an ICE. With HONOR_NANS being false, the real appearance of
355 NaN would cause undefined behavior, though, so claiming that y (and x)
356 are UNDEFINED initially is correct. */
359 canonicalize_float_value (prop_value_t
*val
)
361 enum machine_mode mode
;
365 if (val
->lattice_val
!= CONSTANT
366 || TREE_CODE (val
->value
) != REAL_CST
)
369 d
= TREE_REAL_CST (val
->value
);
370 type
= TREE_TYPE (val
->value
);
371 mode
= TYPE_MODE (type
);
373 if (!HONOR_SIGNED_ZEROS (mode
)
374 && REAL_VALUE_MINUS_ZERO (d
))
376 val
->value
= build_real (type
, dconst0
);
380 if (!HONOR_NANS (mode
)
381 && REAL_VALUE_ISNAN (d
))
383 val
->lattice_val
= UNDEFINED
;
389 /* Return whether the lattice transition is valid. */
392 valid_lattice_transition (prop_value_t old_val
, prop_value_t new_val
)
394 /* Lattice transitions must always be monotonically increasing in
396 if (old_val
.lattice_val
< new_val
.lattice_val
)
399 if (old_val
.lattice_val
!= new_val
.lattice_val
)
402 if (!old_val
.value
&& !new_val
.value
)
405 /* Now both lattice values are CONSTANT. */
407 /* Allow transitioning from PHI <&x, not executable> == &x
408 to PHI <&x, &y> == common alignment. */
409 if (TREE_CODE (old_val
.value
) != INTEGER_CST
410 && TREE_CODE (new_val
.value
) == INTEGER_CST
)
413 /* Bit-lattices have to agree in the still valid bits. */
414 if (TREE_CODE (old_val
.value
) == INTEGER_CST
415 && TREE_CODE (new_val
.value
) == INTEGER_CST
)
416 return double_int_equal_p
417 (double_int_and_not (tree_to_double_int (old_val
.value
),
419 double_int_and_not (tree_to_double_int (new_val
.value
),
422 /* Otherwise constant values have to agree. */
423 return operand_equal_p (old_val
.value
, new_val
.value
, 0);
426 /* Set the value for variable VAR to NEW_VAL. Return true if the new
427 value is different from VAR's previous value. */
430 set_lattice_value (tree var
, prop_value_t new_val
)
432 /* We can deal with old UNINITIALIZED values just fine here. */
433 prop_value_t
*old_val
= &const_val
[SSA_NAME_VERSION (var
)];
435 canonicalize_float_value (&new_val
);
437 /* We have to be careful to not go up the bitwise lattice
438 represented by the mask.
439 ??? This doesn't seem to be the best place to enforce this. */
440 if (new_val
.lattice_val
== CONSTANT
441 && old_val
->lattice_val
== CONSTANT
442 && TREE_CODE (new_val
.value
) == INTEGER_CST
443 && TREE_CODE (old_val
->value
) == INTEGER_CST
)
446 diff
= double_int_xor (tree_to_double_int (new_val
.value
),
447 tree_to_double_int (old_val
->value
));
448 new_val
.mask
= double_int_ior (new_val
.mask
,
449 double_int_ior (old_val
->mask
, diff
));
452 gcc_assert (valid_lattice_transition (*old_val
, new_val
));
454 /* If *OLD_VAL and NEW_VAL are the same, return false to inform the
455 caller that this was a non-transition. */
456 if (old_val
->lattice_val
!= new_val
.lattice_val
457 || (new_val
.lattice_val
== CONSTANT
458 && TREE_CODE (new_val
.value
) == INTEGER_CST
459 && (TREE_CODE (old_val
->value
) != INTEGER_CST
460 || !double_int_equal_p (new_val
.mask
, old_val
->mask
))))
462 /* ??? We would like to delay creation of INTEGER_CSTs from
463 partially constants here. */
465 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
467 dump_lattice_value (dump_file
, "Lattice value changed to ", new_val
);
468 fprintf (dump_file
, ". Adding SSA edges to worklist.\n");
473 gcc_assert (new_val
.lattice_val
!= UNINITIALIZED
);
480 static prop_value_t
get_value_for_expr (tree
, bool);
481 static prop_value_t
bit_value_binop (enum tree_code
, tree
, tree
, tree
);
482 static void bit_value_binop_1 (enum tree_code
, tree
, double_int
*, double_int
*,
483 tree
, double_int
, double_int
,
484 tree
, double_int
, double_int
);
486 /* Return a double_int that can be used for bitwise simplifications
490 value_to_double_int (prop_value_t val
)
493 && TREE_CODE (val
.value
) == INTEGER_CST
)
494 return tree_to_double_int (val
.value
);
496 return double_int_zero
;
499 /* Return the value for the address expression EXPR based on alignment
503 get_value_from_alignment (tree expr
)
505 tree type
= TREE_TYPE (expr
);
507 unsigned HOST_WIDE_INT bitpos
;
510 gcc_assert (TREE_CODE (expr
) == ADDR_EXPR
);
512 get_pointer_alignment_1 (expr
, &align
, &bitpos
);
514 = double_int_and_not (POINTER_TYPE_P (type
) || TYPE_UNSIGNED (type
)
515 ? double_int_mask (TYPE_PRECISION (type
))
516 : double_int_minus_one
,
517 uhwi_to_double_int (align
/ BITS_PER_UNIT
- 1));
518 val
.lattice_val
= double_int_minus_one_p (val
.mask
) ? VARYING
: CONSTANT
;
519 if (val
.lattice_val
== CONSTANT
)
521 = double_int_to_tree (type
, uhwi_to_double_int (bitpos
/ BITS_PER_UNIT
));
523 val
.value
= NULL_TREE
;
528 /* Return the value for the tree operand EXPR. If FOR_BITS_P is true
529 return constant bits extracted from alignment information for
530 invariant addresses. */
533 get_value_for_expr (tree expr
, bool for_bits_p
)
537 if (TREE_CODE (expr
) == SSA_NAME
)
539 val
= *get_value (expr
);
541 && val
.lattice_val
== CONSTANT
542 && TREE_CODE (val
.value
) == ADDR_EXPR
)
543 val
= get_value_from_alignment (val
.value
);
545 else if (is_gimple_min_invariant (expr
)
546 && (!for_bits_p
|| TREE_CODE (expr
) != ADDR_EXPR
))
548 val
.lattice_val
= CONSTANT
;
550 val
.mask
= double_int_zero
;
551 canonicalize_float_value (&val
);
553 else if (TREE_CODE (expr
) == ADDR_EXPR
)
554 val
= get_value_from_alignment (expr
);
557 val
.lattice_val
= VARYING
;
558 val
.mask
= double_int_minus_one
;
559 val
.value
= NULL_TREE
;
564 /* Return the likely CCP lattice value for STMT.
566 If STMT has no operands, then return CONSTANT.
568 Else if undefinedness of operands of STMT cause its value to be
569 undefined, then return UNDEFINED.
571 Else if any operands of STMT are constants, then return CONSTANT.
573 Else return VARYING. */
576 likely_value (gimple stmt
)
578 bool has_constant_operand
, has_undefined_operand
, all_undefined_operands
;
583 enum gimple_code code
= gimple_code (stmt
);
585 /* This function appears to be called only for assignments, calls,
586 conditionals, and switches, due to the logic in visit_stmt. */
587 gcc_assert (code
== GIMPLE_ASSIGN
588 || code
== GIMPLE_CALL
589 || code
== GIMPLE_COND
590 || code
== GIMPLE_SWITCH
);
592 /* If the statement has volatile operands, it won't fold to a
594 if (gimple_has_volatile_ops (stmt
))
597 /* Arrive here for more complex cases. */
598 has_constant_operand
= false;
599 has_undefined_operand
= false;
600 all_undefined_operands
= true;
601 FOR_EACH_SSA_TREE_OPERAND (use
, stmt
, iter
, SSA_OP_USE
)
603 prop_value_t
*val
= get_value (use
);
605 if (val
->lattice_val
== UNDEFINED
)
606 has_undefined_operand
= true;
608 all_undefined_operands
= false;
610 if (val
->lattice_val
== CONSTANT
)
611 has_constant_operand
= true;
614 /* There may be constants in regular rhs operands. For calls we
615 have to ignore lhs, fndecl and static chain, otherwise only
617 for (i
= (is_gimple_call (stmt
) ? 2 : 0) + gimple_has_lhs (stmt
);
618 i
< gimple_num_ops (stmt
); ++i
)
620 tree op
= gimple_op (stmt
, i
);
621 if (!op
|| TREE_CODE (op
) == SSA_NAME
)
623 if (is_gimple_min_invariant (op
))
624 has_constant_operand
= true;
627 if (has_constant_operand
)
628 all_undefined_operands
= false;
630 /* If the operation combines operands like COMPLEX_EXPR make sure to
631 not mark the result UNDEFINED if only one part of the result is
633 if (has_undefined_operand
&& all_undefined_operands
)
635 else if (code
== GIMPLE_ASSIGN
&& has_undefined_operand
)
637 switch (gimple_assign_rhs_code (stmt
))
639 /* Unary operators are handled with all_undefined_operands. */
642 case POINTER_PLUS_EXPR
:
643 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected.
644 Not bitwise operators, one VARYING operand may specify the
645 result completely. Not logical operators for the same reason.
646 Not COMPLEX_EXPR as one VARYING operand makes the result partly
647 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because
648 the undefined operand may be promoted. */
652 /* If any part of an address is UNDEFINED, like the index
653 of an ARRAY_EXPR, then treat the result as UNDEFINED. */
660 /* If there was an UNDEFINED operand but the result may be not UNDEFINED
661 fall back to CONSTANT. During iteration UNDEFINED may still drop
663 if (has_undefined_operand
)
666 /* We do not consider virtual operands here -- load from read-only
667 memory may have only VARYING virtual operands, but still be
669 if (has_constant_operand
670 || gimple_references_memory_p (stmt
))
676 /* Returns true if STMT cannot be constant. */
679 surely_varying_stmt_p (gimple stmt
)
681 /* If the statement has operands that we cannot handle, it cannot be
683 if (gimple_has_volatile_ops (stmt
))
686 /* If it is a call and does not return a value or is not a
687 builtin and not an indirect call, it is varying. */
688 if (is_gimple_call (stmt
))
691 if (!gimple_call_lhs (stmt
)
692 || ((fndecl
= gimple_call_fndecl (stmt
)) != NULL_TREE
693 && !DECL_BUILT_IN (fndecl
)))
697 /* Any other store operation is not interesting. */
698 else if (gimple_vdef (stmt
))
701 /* Anything other than assignments and conditional jumps are not
702 interesting for CCP. */
703 if (gimple_code (stmt
) != GIMPLE_ASSIGN
704 && gimple_code (stmt
) != GIMPLE_COND
705 && gimple_code (stmt
) != GIMPLE_SWITCH
706 && gimple_code (stmt
) != GIMPLE_CALL
)
712 /* Initialize local data structures for CCP. */
715 ccp_initialize (void)
719 const_val
= XCNEWVEC (prop_value_t
, num_ssa_names
);
721 /* Initialize simulation flags for PHI nodes and statements. */
724 gimple_stmt_iterator i
;
726 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); gsi_next (&i
))
728 gimple stmt
= gsi_stmt (i
);
731 /* If the statement is a control insn, then we do not
732 want to avoid simulating the statement once. Failure
733 to do so means that those edges will never get added. */
734 if (stmt_ends_bb_p (stmt
))
737 is_varying
= surely_varying_stmt_p (stmt
);
744 /* If the statement will not produce a constant, mark
745 all its outputs VARYING. */
746 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
747 set_value_varying (def
);
749 prop_set_simulate_again (stmt
, !is_varying
);
753 /* Now process PHI nodes. We never clear the simulate_again flag on
754 phi nodes, since we do not know which edges are executable yet,
755 except for phi nodes for virtual operands when we do not do store ccp. */
758 gimple_stmt_iterator i
;
760 for (i
= gsi_start_phis (bb
); !gsi_end_p (i
); gsi_next (&i
))
762 gimple phi
= gsi_stmt (i
);
764 if (virtual_operand_p (gimple_phi_result (phi
)))
765 prop_set_simulate_again (phi
, false);
767 prop_set_simulate_again (phi
, true);
772 /* Debug count support. Reset the values of ssa names
773 VARYING when the total number ssa names analyzed is
774 beyond the debug count specified. */
780 for (i
= 0; i
< num_ssa_names
; i
++)
784 const_val
[i
].lattice_val
= VARYING
;
785 const_val
[i
].mask
= double_int_minus_one
;
786 const_val
[i
].value
= NULL_TREE
;
792 /* Do final substitution of propagated values, cleanup the flowgraph and
793 free allocated storage.
795 Return TRUE when something was optimized. */
800 bool something_changed
;
805 /* Derive alignment and misalignment information from partially
806 constant pointers in the lattice. */
807 for (i
= 1; i
< num_ssa_names
; ++i
)
809 tree name
= ssa_name (i
);
811 unsigned int tem
, align
;
814 || !POINTER_TYPE_P (TREE_TYPE (name
)))
817 val
= get_value (name
);
818 if (val
->lattice_val
!= CONSTANT
819 || TREE_CODE (val
->value
) != INTEGER_CST
)
822 /* Trailing constant bits specify the alignment, trailing value
823 bits the misalignment. */
825 align
= (tem
& -tem
);
827 set_ptr_info_alignment (get_ptr_info (name
), align
,
828 TREE_INT_CST_LOW (val
->value
) & (align
- 1));
831 /* Perform substitutions based on the known constant values. */
832 something_changed
= substitute_and_fold (get_constant_value
,
833 ccp_fold_stmt
, true);
837 return something_changed
;;
841 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
844 any M UNDEFINED = any
845 any M VARYING = VARYING
846 Ci M Cj = Ci if (i == j)
847 Ci M Cj = VARYING if (i != j)
851 ccp_lattice_meet (prop_value_t
*val1
, prop_value_t
*val2
)
853 if (val1
->lattice_val
== UNDEFINED
)
855 /* UNDEFINED M any = any */
858 else if (val2
->lattice_val
== UNDEFINED
)
860 /* any M UNDEFINED = any
861 Nothing to do. VAL1 already contains the value we want. */
864 else if (val1
->lattice_val
== VARYING
865 || val2
->lattice_val
== VARYING
)
867 /* any M VARYING = VARYING. */
868 val1
->lattice_val
= VARYING
;
869 val1
->mask
= double_int_minus_one
;
870 val1
->value
= NULL_TREE
;
872 else if (val1
->lattice_val
== CONSTANT
873 && val2
->lattice_val
== CONSTANT
874 && TREE_CODE (val1
->value
) == INTEGER_CST
875 && TREE_CODE (val2
->value
) == INTEGER_CST
)
877 /* Ci M Cj = Ci if (i == j)
878 Ci M Cj = VARYING if (i != j)
880 For INTEGER_CSTs mask unequal bits. If no equal bits remain,
883 = double_int_ior (double_int_ior (val1
->mask
,
885 double_int_xor (tree_to_double_int (val1
->value
),
886 tree_to_double_int (val2
->value
)));
887 if (double_int_minus_one_p (val1
->mask
))
889 val1
->lattice_val
= VARYING
;
890 val1
->value
= NULL_TREE
;
893 else if (val1
->lattice_val
== CONSTANT
894 && val2
->lattice_val
== CONSTANT
895 && simple_cst_equal (val1
->value
, val2
->value
) == 1)
897 /* Ci M Cj = Ci if (i == j)
898 Ci M Cj = VARYING if (i != j)
900 VAL1 already contains the value we want for equivalent values. */
902 else if (val1
->lattice_val
== CONSTANT
903 && val2
->lattice_val
== CONSTANT
904 && (TREE_CODE (val1
->value
) == ADDR_EXPR
905 || TREE_CODE (val2
->value
) == ADDR_EXPR
))
907 /* When not equal addresses are involved try meeting for
909 prop_value_t tem
= *val2
;
910 if (TREE_CODE (val1
->value
) == ADDR_EXPR
)
911 *val1
= get_value_for_expr (val1
->value
, true);
912 if (TREE_CODE (val2
->value
) == ADDR_EXPR
)
913 tem
= get_value_for_expr (val2
->value
, true);
914 ccp_lattice_meet (val1
, &tem
);
918 /* Any other combination is VARYING. */
919 val1
->lattice_val
= VARYING
;
920 val1
->mask
= double_int_minus_one
;
921 val1
->value
= NULL_TREE
;
926 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
927 lattice values to determine PHI_NODE's lattice value. The value of a
928 PHI node is determined calling ccp_lattice_meet with all the arguments
929 of the PHI node that are incoming via executable edges. */
931 static enum ssa_prop_result
932 ccp_visit_phi_node (gimple phi
)
935 prop_value_t
*old_val
, new_val
;
937 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
939 fprintf (dump_file
, "\nVisiting PHI node: ");
940 print_gimple_stmt (dump_file
, phi
, 0, dump_flags
);
943 old_val
= get_value (gimple_phi_result (phi
));
944 switch (old_val
->lattice_val
)
947 return SSA_PROP_VARYING
;
954 new_val
.lattice_val
= UNDEFINED
;
955 new_val
.value
= NULL_TREE
;
962 for (i
= 0; i
< gimple_phi_num_args (phi
); i
++)
964 /* Compute the meet operator over all the PHI arguments flowing
965 through executable edges. */
966 edge e
= gimple_phi_arg_edge (phi
, i
);
968 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
971 "\n Argument #%d (%d -> %d %sexecutable)\n",
972 i
, e
->src
->index
, e
->dest
->index
,
973 (e
->flags
& EDGE_EXECUTABLE
) ? "" : "not ");
976 /* If the incoming edge is executable, Compute the meet operator for
977 the existing value of the PHI node and the current PHI argument. */
978 if (e
->flags
& EDGE_EXECUTABLE
)
980 tree arg
= gimple_phi_arg (phi
, i
)->def
;
981 prop_value_t arg_val
= get_value_for_expr (arg
, false);
983 ccp_lattice_meet (&new_val
, &arg_val
);
985 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
987 fprintf (dump_file
, "\t");
988 print_generic_expr (dump_file
, arg
, dump_flags
);
989 dump_lattice_value (dump_file
, "\tValue: ", arg_val
);
990 fprintf (dump_file
, "\n");
993 if (new_val
.lattice_val
== VARYING
)
998 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1000 dump_lattice_value (dump_file
, "\n PHI node value: ", new_val
);
1001 fprintf (dump_file
, "\n\n");
1004 /* Make the transition to the new value. */
1005 if (set_lattice_value (gimple_phi_result (phi
), new_val
))
1007 if (new_val
.lattice_val
== VARYING
)
1008 return SSA_PROP_VARYING
;
1010 return SSA_PROP_INTERESTING
;
1013 return SSA_PROP_NOT_INTERESTING
;
1016 /* Return the constant value for OP or OP otherwise. */
1019 valueize_op (tree op
)
1021 if (TREE_CODE (op
) == SSA_NAME
)
1023 tree tem
= get_constant_value (op
);
1030 /* CCP specific front-end to the non-destructive constant folding
1033 Attempt to simplify the RHS of STMT knowing that one or more
1034 operands are constants.
1036 If simplification is possible, return the simplified RHS,
1037 otherwise return the original RHS or NULL_TREE. */
1040 ccp_fold (gimple stmt
)
1042 location_t loc
= gimple_location (stmt
);
1043 switch (gimple_code (stmt
))
1047 /* Handle comparison operators that can appear in GIMPLE form. */
1048 tree op0
= valueize_op (gimple_cond_lhs (stmt
));
1049 tree op1
= valueize_op (gimple_cond_rhs (stmt
));
1050 enum tree_code code
= gimple_cond_code (stmt
);
1051 return fold_binary_loc (loc
, code
, boolean_type_node
, op0
, op1
);
1056 /* Return the constant switch index. */
1057 return valueize_op (gimple_switch_index (stmt
));
1062 return gimple_fold_stmt_to_constant_1 (stmt
, valueize_op
);
1069 /* Apply the operation CODE in type TYPE to the value, mask pair
1070 RVAL and RMASK representing a value of type RTYPE and set
1071 the value, mask pair *VAL and *MASK to the result. */
1074 bit_value_unop_1 (enum tree_code code
, tree type
,
1075 double_int
*val
, double_int
*mask
,
1076 tree rtype
, double_int rval
, double_int rmask
)
1082 *val
= double_int_not (rval
);
1087 double_int temv
, temm
;
1088 /* Return ~rval + 1. */
1089 bit_value_unop_1 (BIT_NOT_EXPR
, type
, &temv
, &temm
, type
, rval
, rmask
);
1090 bit_value_binop_1 (PLUS_EXPR
, type
, val
, mask
,
1092 type
, double_int_one
, double_int_zero
);
1100 /* First extend mask and value according to the original type. */
1101 uns
= TYPE_UNSIGNED (rtype
);
1102 *mask
= double_int_ext (rmask
, TYPE_PRECISION (rtype
), uns
);
1103 *val
= double_int_ext (rval
, TYPE_PRECISION (rtype
), uns
);
1105 /* Then extend mask and value according to the target type. */
1106 uns
= TYPE_UNSIGNED (type
);
1107 *mask
= double_int_ext (*mask
, TYPE_PRECISION (type
), uns
);
1108 *val
= double_int_ext (*val
, TYPE_PRECISION (type
), uns
);
1113 *mask
= double_int_minus_one
;
1118 /* Apply the operation CODE in type TYPE to the value, mask pairs
1119 R1VAL, R1MASK and R2VAL, R2MASK representing a values of type R1TYPE
1120 and R2TYPE and set the value, mask pair *VAL and *MASK to the result. */
1123 bit_value_binop_1 (enum tree_code code
, tree type
,
1124 double_int
*val
, double_int
*mask
,
1125 tree r1type
, double_int r1val
, double_int r1mask
,
1126 tree r2type
, double_int r2val
, double_int r2mask
)
1128 bool uns
= TYPE_UNSIGNED (type
);
1129 /* Assume we'll get a constant result. Use an initial varying value,
1130 we fall back to varying in the end if necessary. */
1131 *mask
= double_int_minus_one
;
1135 /* The mask is constant where there is a known not
1136 set bit, (m1 | m2) & ((v1 | m1) & (v2 | m2)) */
1137 *mask
= double_int_and (double_int_ior (r1mask
, r2mask
),
1138 double_int_and (double_int_ior (r1val
, r1mask
),
1139 double_int_ior (r2val
, r2mask
)));
1140 *val
= double_int_and (r1val
, r2val
);
1144 /* The mask is constant where there is a known
1145 set bit, (m1 | m2) & ~((v1 & ~m1) | (v2 & ~m2)). */
1146 *mask
= double_int_and_not
1147 (double_int_ior (r1mask
, r2mask
),
1148 double_int_ior (double_int_and_not (r1val
, r1mask
),
1149 double_int_and_not (r2val
, r2mask
)));
1150 *val
= double_int_ior (r1val
, r2val
);
1155 *mask
= double_int_ior (r1mask
, r2mask
);
1156 *val
= double_int_xor (r1val
, r2val
);
1161 if (double_int_zero_p (r2mask
))
1163 HOST_WIDE_INT shift
= r2val
.low
;
1164 if (code
== RROTATE_EXPR
)
1166 *mask
= double_int_lrotate (r1mask
, shift
, TYPE_PRECISION (type
));
1167 *val
= double_int_lrotate (r1val
, shift
, TYPE_PRECISION (type
));
1173 /* ??? We can handle partially known shift counts if we know
1174 its sign. That way we can tell that (x << (y | 8)) & 255
1176 if (double_int_zero_p (r2mask
))
1178 HOST_WIDE_INT shift
= r2val
.low
;
1179 if (code
== RSHIFT_EXPR
)
1181 /* We need to know if we are doing a left or a right shift
1182 to properly shift in zeros for left shift and unsigned
1183 right shifts and the sign bit for signed right shifts.
1184 For signed right shifts we shift in varying in case
1185 the sign bit was varying. */
1188 *mask
= double_int_lshift (r1mask
, shift
,
1189 TYPE_PRECISION (type
), false);
1190 *val
= double_int_lshift (r1val
, shift
,
1191 TYPE_PRECISION (type
), false);
1196 *mask
= double_int_rshift (r1mask
, shift
,
1197 TYPE_PRECISION (type
), !uns
);
1198 *val
= double_int_rshift (r1val
, shift
,
1199 TYPE_PRECISION (type
), !uns
);
1210 case POINTER_PLUS_EXPR
:
1213 /* Do the addition with unknown bits set to zero, to give carry-ins of
1214 zero wherever possible. */
1215 lo
= double_int_add (double_int_and_not (r1val
, r1mask
),
1216 double_int_and_not (r2val
, r2mask
));
1217 lo
= double_int_ext (lo
, TYPE_PRECISION (type
), uns
);
1218 /* Do the addition with unknown bits set to one, to give carry-ins of
1219 one wherever possible. */
1220 hi
= double_int_add (double_int_ior (r1val
, r1mask
),
1221 double_int_ior (r2val
, r2mask
));
1222 hi
= double_int_ext (hi
, TYPE_PRECISION (type
), uns
);
1223 /* Each bit in the result is known if (a) the corresponding bits in
1224 both inputs are known, and (b) the carry-in to that bit position
1225 is known. We can check condition (b) by seeing if we got the same
1226 result with minimised carries as with maximised carries. */
1227 *mask
= double_int_ior (double_int_ior (r1mask
, r2mask
),
1228 double_int_xor (lo
, hi
));
1229 *mask
= double_int_ext (*mask
, TYPE_PRECISION (type
), uns
);
1230 /* It shouldn't matter whether we choose lo or hi here. */
1237 double_int temv
, temm
;
1238 bit_value_unop_1 (NEGATE_EXPR
, r2type
, &temv
, &temm
,
1239 r2type
, r2val
, r2mask
);
1240 bit_value_binop_1 (PLUS_EXPR
, type
, val
, mask
,
1241 r1type
, r1val
, r1mask
,
1242 r2type
, temv
, temm
);
1248 /* Just track trailing zeros in both operands and transfer
1249 them to the other. */
1250 int r1tz
= double_int_ctz (double_int_ior (r1val
, r1mask
));
1251 int r2tz
= double_int_ctz (double_int_ior (r2val
, r2mask
));
1252 if (r1tz
+ r2tz
>= HOST_BITS_PER_DOUBLE_INT
)
1254 *mask
= double_int_zero
;
1255 *val
= double_int_zero
;
1257 else if (r1tz
+ r2tz
> 0)
1259 *mask
= double_int_not (double_int_mask (r1tz
+ r2tz
));
1260 *mask
= double_int_ext (*mask
, TYPE_PRECISION (type
), uns
);
1261 *val
= double_int_zero
;
1269 double_int m
= double_int_ior (r1mask
, r2mask
);
1270 if (!double_int_equal_p (double_int_and_not (r1val
, m
),
1271 double_int_and_not (r2val
, m
)))
1273 *mask
= double_int_zero
;
1274 *val
= ((code
== EQ_EXPR
) ? double_int_zero
: double_int_one
);
1278 /* We know the result of a comparison is always one or zero. */
1279 *mask
= double_int_one
;
1280 *val
= double_int_zero
;
1288 double_int tem
= r1val
;
1294 code
= swap_tree_comparison (code
);
1301 /* If the most significant bits are not known we know nothing. */
1302 if (double_int_negative_p (r1mask
) || double_int_negative_p (r2mask
))
1305 /* For comparisons the signedness is in the comparison operands. */
1306 uns
= TYPE_UNSIGNED (r1type
);
1308 /* If we know the most significant bits we know the values
1309 value ranges by means of treating varying bits as zero
1310 or one. Do a cross comparison of the max/min pairs. */
1311 maxmin
= double_int_cmp (double_int_ior (r1val
, r1mask
),
1312 double_int_and_not (r2val
, r2mask
), uns
);
1313 minmax
= double_int_cmp (double_int_and_not (r1val
, r1mask
),
1314 double_int_ior (r2val
, r2mask
), uns
);
1315 if (maxmin
< 0) /* r1 is less than r2. */
1317 *mask
= double_int_zero
;
1318 *val
= double_int_one
;
1320 else if (minmax
> 0) /* r1 is not less or equal to r2. */
1322 *mask
= double_int_zero
;
1323 *val
= double_int_zero
;
1325 else if (maxmin
== minmax
) /* r1 and r2 are equal. */
1327 /* This probably should never happen as we'd have
1328 folded the thing during fully constant value folding. */
1329 *mask
= double_int_zero
;
1330 *val
= (code
== LE_EXPR
? double_int_one
: double_int_zero
);
1334 /* We know the result of a comparison is always one or zero. */
1335 *mask
= double_int_one
;
1336 *val
= double_int_zero
;
1345 /* Return the propagation value when applying the operation CODE to
1346 the value RHS yielding type TYPE. */
1349 bit_value_unop (enum tree_code code
, tree type
, tree rhs
)
1351 prop_value_t rval
= get_value_for_expr (rhs
, true);
1352 double_int value
, mask
;
1355 if (rval
.lattice_val
== UNDEFINED
)
1358 gcc_assert ((rval
.lattice_val
== CONSTANT
1359 && TREE_CODE (rval
.value
) == INTEGER_CST
)
1360 || double_int_minus_one_p (rval
.mask
));
1361 bit_value_unop_1 (code
, type
, &value
, &mask
,
1362 TREE_TYPE (rhs
), value_to_double_int (rval
), rval
.mask
);
1363 if (!double_int_minus_one_p (mask
))
1365 val
.lattice_val
= CONSTANT
;
1367 /* ??? Delay building trees here. */
1368 val
.value
= double_int_to_tree (type
, value
);
1372 val
.lattice_val
= VARYING
;
1373 val
.value
= NULL_TREE
;
1374 val
.mask
= double_int_minus_one
;
1379 /* Return the propagation value when applying the operation CODE to
1380 the values RHS1 and RHS2 yielding type TYPE. */
1383 bit_value_binop (enum tree_code code
, tree type
, tree rhs1
, tree rhs2
)
1385 prop_value_t r1val
= get_value_for_expr (rhs1
, true);
1386 prop_value_t r2val
= get_value_for_expr (rhs2
, true);
1387 double_int value
, mask
;
1390 if (r1val
.lattice_val
== UNDEFINED
1391 || r2val
.lattice_val
== UNDEFINED
)
1393 val
.lattice_val
= VARYING
;
1394 val
.value
= NULL_TREE
;
1395 val
.mask
= double_int_minus_one
;
1399 gcc_assert ((r1val
.lattice_val
== CONSTANT
1400 && TREE_CODE (r1val
.value
) == INTEGER_CST
)
1401 || double_int_minus_one_p (r1val
.mask
));
1402 gcc_assert ((r2val
.lattice_val
== CONSTANT
1403 && TREE_CODE (r2val
.value
) == INTEGER_CST
)
1404 || double_int_minus_one_p (r2val
.mask
));
1405 bit_value_binop_1 (code
, type
, &value
, &mask
,
1406 TREE_TYPE (rhs1
), value_to_double_int (r1val
), r1val
.mask
,
1407 TREE_TYPE (rhs2
), value_to_double_int (r2val
), r2val
.mask
);
1408 if (!double_int_minus_one_p (mask
))
1410 val
.lattice_val
= CONSTANT
;
1412 /* ??? Delay building trees here. */
1413 val
.value
= double_int_to_tree (type
, value
);
1417 val
.lattice_val
= VARYING
;
1418 val
.value
= NULL_TREE
;
1419 val
.mask
= double_int_minus_one
;
1424 /* Return the propagation value when applying __builtin_assume_aligned to
1428 bit_value_assume_aligned (gimple stmt
)
1430 tree ptr
= gimple_call_arg (stmt
, 0), align
, misalign
= NULL_TREE
;
1431 tree type
= TREE_TYPE (ptr
);
1432 unsigned HOST_WIDE_INT aligni
, misaligni
= 0;
1433 prop_value_t ptrval
= get_value_for_expr (ptr
, true);
1434 prop_value_t alignval
;
1435 double_int value
, mask
;
1437 if (ptrval
.lattice_val
== UNDEFINED
)
1439 gcc_assert ((ptrval
.lattice_val
== CONSTANT
1440 && TREE_CODE (ptrval
.value
) == INTEGER_CST
)
1441 || double_int_minus_one_p (ptrval
.mask
));
1442 align
= gimple_call_arg (stmt
, 1);
1443 if (!host_integerp (align
, 1))
1445 aligni
= tree_low_cst (align
, 1);
1447 || (aligni
& (aligni
- 1)) != 0)
1449 if (gimple_call_num_args (stmt
) > 2)
1451 misalign
= gimple_call_arg (stmt
, 2);
1452 if (!host_integerp (misalign
, 1))
1454 misaligni
= tree_low_cst (misalign
, 1);
1455 if (misaligni
>= aligni
)
1458 align
= build_int_cst_type (type
, -aligni
);
1459 alignval
= get_value_for_expr (align
, true);
1460 bit_value_binop_1 (BIT_AND_EXPR
, type
, &value
, &mask
,
1461 type
, value_to_double_int (ptrval
), ptrval
.mask
,
1462 type
, value_to_double_int (alignval
), alignval
.mask
);
1463 if (!double_int_minus_one_p (mask
))
1465 val
.lattice_val
= CONSTANT
;
1467 gcc_assert ((mask
.low
& (aligni
- 1)) == 0);
1468 gcc_assert ((value
.low
& (aligni
- 1)) == 0);
1469 value
.low
|= misaligni
;
1470 /* ??? Delay building trees here. */
1471 val
.value
= double_int_to_tree (type
, value
);
1475 val
.lattice_val
= VARYING
;
1476 val
.value
= NULL_TREE
;
1477 val
.mask
= double_int_minus_one
;
1482 /* Evaluate statement STMT.
1483 Valid only for assignments, calls, conditionals, and switches. */
1486 evaluate_stmt (gimple stmt
)
1489 tree simplified
= NULL_TREE
;
1490 ccp_lattice_t likelyvalue
= likely_value (stmt
);
1491 bool is_constant
= false;
1494 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1496 fprintf (dump_file
, "which is likely ");
1497 switch (likelyvalue
)
1500 fprintf (dump_file
, "CONSTANT");
1503 fprintf (dump_file
, "UNDEFINED");
1506 fprintf (dump_file
, "VARYING");
1510 fprintf (dump_file
, "\n");
1513 /* If the statement is likely to have a CONSTANT result, then try
1514 to fold the statement to determine the constant value. */
1515 /* FIXME. This is the only place that we call ccp_fold.
1516 Since likely_value never returns CONSTANT for calls, we will
1517 not attempt to fold them, including builtins that may profit. */
1518 if (likelyvalue
== CONSTANT
)
1520 fold_defer_overflow_warnings ();
1521 simplified
= ccp_fold (stmt
);
1522 is_constant
= simplified
&& is_gimple_min_invariant (simplified
);
1523 fold_undefer_overflow_warnings (is_constant
, stmt
, 0);
1526 /* The statement produced a constant value. */
1527 val
.lattice_val
= CONSTANT
;
1528 val
.value
= simplified
;
1529 val
.mask
= double_int_zero
;
1532 /* If the statement is likely to have a VARYING result, then do not
1533 bother folding the statement. */
1534 else if (likelyvalue
== VARYING
)
1536 enum gimple_code code
= gimple_code (stmt
);
1537 if (code
== GIMPLE_ASSIGN
)
1539 enum tree_code subcode
= gimple_assign_rhs_code (stmt
);
1541 /* Other cases cannot satisfy is_gimple_min_invariant
1543 if (get_gimple_rhs_class (subcode
) == GIMPLE_SINGLE_RHS
)
1544 simplified
= gimple_assign_rhs1 (stmt
);
1546 else if (code
== GIMPLE_SWITCH
)
1547 simplified
= gimple_switch_index (stmt
);
1549 /* These cannot satisfy is_gimple_min_invariant without folding. */
1550 gcc_assert (code
== GIMPLE_CALL
|| code
== GIMPLE_COND
);
1551 is_constant
= simplified
&& is_gimple_min_invariant (simplified
);
1554 /* The statement produced a constant value. */
1555 val
.lattice_val
= CONSTANT
;
1556 val
.value
= simplified
;
1557 val
.mask
= double_int_zero
;
1561 /* Resort to simplification for bitwise tracking. */
1562 if (flag_tree_bit_ccp
1563 && (likelyvalue
== CONSTANT
|| is_gimple_call (stmt
))
1566 enum gimple_code code
= gimple_code (stmt
);
1568 val
.lattice_val
= VARYING
;
1569 val
.value
= NULL_TREE
;
1570 val
.mask
= double_int_minus_one
;
1571 if (code
== GIMPLE_ASSIGN
)
1573 enum tree_code subcode
= gimple_assign_rhs_code (stmt
);
1574 tree rhs1
= gimple_assign_rhs1 (stmt
);
1575 switch (get_gimple_rhs_class (subcode
))
1577 case GIMPLE_SINGLE_RHS
:
1578 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1579 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1580 val
= get_value_for_expr (rhs1
, true);
1583 case GIMPLE_UNARY_RHS
:
1584 if ((INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1585 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1586 && (INTEGRAL_TYPE_P (gimple_expr_type (stmt
))
1587 || POINTER_TYPE_P (gimple_expr_type (stmt
))))
1588 val
= bit_value_unop (subcode
, gimple_expr_type (stmt
), rhs1
);
1591 case GIMPLE_BINARY_RHS
:
1592 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1593 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1595 tree lhs
= gimple_assign_lhs (stmt
);
1596 tree rhs2
= gimple_assign_rhs2 (stmt
);
1597 val
= bit_value_binop (subcode
,
1598 TREE_TYPE (lhs
), rhs1
, rhs2
);
1605 else if (code
== GIMPLE_COND
)
1607 enum tree_code code
= gimple_cond_code (stmt
);
1608 tree rhs1
= gimple_cond_lhs (stmt
);
1609 tree rhs2
= gimple_cond_rhs (stmt
);
1610 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1
))
1611 || POINTER_TYPE_P (TREE_TYPE (rhs1
)))
1612 val
= bit_value_binop (code
, TREE_TYPE (rhs1
), rhs1
, rhs2
);
1614 else if (code
== GIMPLE_CALL
1615 && (fndecl
= gimple_call_fndecl (stmt
))
1616 && DECL_BUILT_IN_CLASS (fndecl
) == BUILT_IN_NORMAL
)
1618 switch (DECL_FUNCTION_CODE (fndecl
))
1620 case BUILT_IN_MALLOC
:
1621 case BUILT_IN_REALLOC
:
1622 case BUILT_IN_CALLOC
:
1623 case BUILT_IN_STRDUP
:
1624 case BUILT_IN_STRNDUP
:
1625 val
.lattice_val
= CONSTANT
;
1626 val
.value
= build_int_cst (TREE_TYPE (gimple_get_lhs (stmt
)), 0);
1627 val
.mask
= shwi_to_double_int
1628 (~(((HOST_WIDE_INT
) MALLOC_ABI_ALIGNMENT
)
1629 / BITS_PER_UNIT
- 1));
1632 case BUILT_IN_ALLOCA
:
1633 case BUILT_IN_ALLOCA_WITH_ALIGN
:
1634 align
= (DECL_FUNCTION_CODE (fndecl
) == BUILT_IN_ALLOCA_WITH_ALIGN
1635 ? TREE_INT_CST_LOW (gimple_call_arg (stmt
, 1))
1636 : BIGGEST_ALIGNMENT
);
1637 val
.lattice_val
= CONSTANT
;
1638 val
.value
= build_int_cst (TREE_TYPE (gimple_get_lhs (stmt
)), 0);
1639 val
.mask
= shwi_to_double_int
1640 (~(((HOST_WIDE_INT
) align
)
1641 / BITS_PER_UNIT
- 1));
1644 /* These builtins return their first argument, unmodified. */
1645 case BUILT_IN_MEMCPY
:
1646 case BUILT_IN_MEMMOVE
:
1647 case BUILT_IN_MEMSET
:
1648 case BUILT_IN_STRCPY
:
1649 case BUILT_IN_STRNCPY
:
1650 case BUILT_IN_MEMCPY_CHK
:
1651 case BUILT_IN_MEMMOVE_CHK
:
1652 case BUILT_IN_MEMSET_CHK
:
1653 case BUILT_IN_STRCPY_CHK
:
1654 case BUILT_IN_STRNCPY_CHK
:
1655 val
= get_value_for_expr (gimple_call_arg (stmt
, 0), true);
1658 case BUILT_IN_ASSUME_ALIGNED
:
1659 val
= bit_value_assume_aligned (stmt
);
1665 is_constant
= (val
.lattice_val
== CONSTANT
);
1670 /* The statement produced a nonconstant value. If the statement
1671 had UNDEFINED operands, then the result of the statement
1672 should be UNDEFINED. Otherwise, the statement is VARYING. */
1673 if (likelyvalue
== UNDEFINED
)
1675 val
.lattice_val
= likelyvalue
;
1676 val
.mask
= double_int_zero
;
1680 val
.lattice_val
= VARYING
;
1681 val
.mask
= double_int_minus_one
;
1684 val
.value
= NULL_TREE
;
1690 /* Given a BUILT_IN_STACK_SAVE value SAVED_VAL, insert a clobber of VAR before
1691 each matching BUILT_IN_STACK_RESTORE. Mark visited phis in VISITED. */
1694 insert_clobber_before_stack_restore (tree saved_val
, tree var
, htab_t
*visited
)
1696 gimple stmt
, clobber_stmt
;
1698 imm_use_iterator iter
;
1699 gimple_stmt_iterator i
;
1702 FOR_EACH_IMM_USE_STMT (stmt
, iter
, saved_val
)
1703 if (gimple_call_builtin_p (stmt
, BUILT_IN_STACK_RESTORE
))
1705 clobber
= build_constructor (TREE_TYPE (var
), NULL
);
1706 TREE_THIS_VOLATILE (clobber
) = 1;
1707 clobber_stmt
= gimple_build_assign (var
, clobber
);
1709 i
= gsi_for_stmt (stmt
);
1710 gsi_insert_before (&i
, clobber_stmt
, GSI_SAME_STMT
);
1712 else if (gimple_code (stmt
) == GIMPLE_PHI
)
1714 if (*visited
== NULL
)
1715 *visited
= htab_create (10, htab_hash_pointer
, htab_eq_pointer
, NULL
);
1717 slot
= (gimple
*)htab_find_slot (*visited
, stmt
, INSERT
);
1722 insert_clobber_before_stack_restore (gimple_phi_result (stmt
), var
,
1726 gcc_assert (is_gimple_debug (stmt
));
1729 /* Advance the iterator to the previous non-debug gimple statement in the same
1730 or dominating basic block. */
1733 gsi_prev_dom_bb_nondebug (gimple_stmt_iterator
*i
)
1737 gsi_prev_nondebug (i
);
1738 while (gsi_end_p (*i
))
1740 dom
= get_immediate_dominator (CDI_DOMINATORS
, i
->bb
);
1741 if (dom
== NULL
|| dom
== ENTRY_BLOCK_PTR
)
1744 *i
= gsi_last_bb (dom
);
1748 /* Find a BUILT_IN_STACK_SAVE dominating gsi_stmt (I), and insert
1749 a clobber of VAR before each matching BUILT_IN_STACK_RESTORE.
1751 It is possible that BUILT_IN_STACK_SAVE cannot be find in a dominator when a
1752 previous pass (such as DOM) duplicated it along multiple paths to a BB. In
1753 that case the function gives up without inserting the clobbers. */
1756 insert_clobbers_for_var (gimple_stmt_iterator i
, tree var
)
1760 htab_t visited
= NULL
;
1762 for (; !gsi_end_p (i
); gsi_prev_dom_bb_nondebug (&i
))
1764 stmt
= gsi_stmt (i
);
1766 if (!gimple_call_builtin_p (stmt
, BUILT_IN_STACK_SAVE
))
1769 saved_val
= gimple_call_lhs (stmt
);
1770 if (saved_val
== NULL_TREE
)
1773 insert_clobber_before_stack_restore (saved_val
, var
, &visited
);
1777 if (visited
!= NULL
)
1778 htab_delete (visited
);
1781 /* Detects a __builtin_alloca_with_align with constant size argument. Declares
1782 fixed-size array and returns the address, if found, otherwise returns
1786 fold_builtin_alloca_with_align (gimple stmt
)
1788 unsigned HOST_WIDE_INT size
, threshold
, n_elem
;
1789 tree lhs
, arg
, block
, var
, elem_type
, array_type
;
1792 lhs
= gimple_call_lhs (stmt
);
1793 if (lhs
== NULL_TREE
)
1796 /* Detect constant argument. */
1797 arg
= get_constant_value (gimple_call_arg (stmt
, 0));
1798 if (arg
== NULL_TREE
1799 || TREE_CODE (arg
) != INTEGER_CST
1800 || !host_integerp (arg
, 1))
1803 size
= TREE_INT_CST_LOW (arg
);
1805 /* Heuristic: don't fold large allocas. */
1806 threshold
= (unsigned HOST_WIDE_INT
)PARAM_VALUE (PARAM_LARGE_STACK_FRAME
);
1807 /* In case the alloca is located at function entry, it has the same lifetime
1808 as a declared array, so we allow a larger size. */
1809 block
= gimple_block (stmt
);
1810 if (!(cfun
->after_inlining
1811 && TREE_CODE (BLOCK_SUPERCONTEXT (block
)) == FUNCTION_DECL
))
1813 if (size
> threshold
)
1816 /* Declare array. */
1817 elem_type
= build_nonstandard_integer_type (BITS_PER_UNIT
, 1);
1818 n_elem
= size
* 8 / BITS_PER_UNIT
;
1819 array_type
= build_array_type_nelts (elem_type
, n_elem
);
1820 var
= create_tmp_var (array_type
, NULL
);
1821 DECL_ALIGN (var
) = TREE_INT_CST_LOW (gimple_call_arg (stmt
, 1));
1823 struct ptr_info_def
*pi
= SSA_NAME_PTR_INFO (lhs
);
1824 if (pi
!= NULL
&& !pi
->pt
.anything
)
1828 singleton_p
= pt_solution_singleton_p (&pi
->pt
, &uid
);
1829 gcc_assert (singleton_p
);
1830 SET_DECL_PT_UID (var
, uid
);
1834 /* Fold alloca to the address of the array. */
1835 return fold_convert (TREE_TYPE (lhs
), build_fold_addr_expr (var
));
1838 /* Fold the stmt at *GSI with CCP specific information that propagating
1839 and regular folding does not catch. */
1842 ccp_fold_stmt (gimple_stmt_iterator
*gsi
)
1844 gimple stmt
= gsi_stmt (*gsi
);
1846 switch (gimple_code (stmt
))
1851 /* Statement evaluation will handle type mismatches in constants
1852 more gracefully than the final propagation. This allows us to
1853 fold more conditionals here. */
1854 val
= evaluate_stmt (stmt
);
1855 if (val
.lattice_val
!= CONSTANT
1856 || !double_int_zero_p (val
.mask
))
1861 fprintf (dump_file
, "Folding predicate ");
1862 print_gimple_expr (dump_file
, stmt
, 0, 0);
1863 fprintf (dump_file
, " to ");
1864 print_generic_expr (dump_file
, val
.value
, 0);
1865 fprintf (dump_file
, "\n");
1868 if (integer_zerop (val
.value
))
1869 gimple_cond_make_false (stmt
);
1871 gimple_cond_make_true (stmt
);
1878 tree lhs
= gimple_call_lhs (stmt
);
1879 int flags
= gimple_call_flags (stmt
);
1882 bool changed
= false;
1885 /* If the call was folded into a constant make sure it goes
1886 away even if we cannot propagate into all uses because of
1889 && TREE_CODE (lhs
) == SSA_NAME
1890 && (val
= get_constant_value (lhs
))
1891 /* Don't optimize away calls that have side-effects. */
1892 && (flags
& (ECF_CONST
|ECF_PURE
)) != 0
1893 && (flags
& ECF_LOOPING_CONST_OR_PURE
) == 0)
1895 tree new_rhs
= unshare_expr (val
);
1897 if (!useless_type_conversion_p (TREE_TYPE (lhs
),
1898 TREE_TYPE (new_rhs
)))
1899 new_rhs
= fold_convert (TREE_TYPE (lhs
), new_rhs
);
1900 res
= update_call_from_tree (gsi
, new_rhs
);
1905 /* Internal calls provide no argument types, so the extra laxity
1906 for normal calls does not apply. */
1907 if (gimple_call_internal_p (stmt
))
1910 /* The heuristic of fold_builtin_alloca_with_align differs before and
1911 after inlining, so we don't require the arg to be changed into a
1912 constant for folding, but just to be constant. */
1913 if (gimple_call_builtin_p (stmt
, BUILT_IN_ALLOCA_WITH_ALIGN
))
1915 tree new_rhs
= fold_builtin_alloca_with_align (stmt
);
1918 bool res
= update_call_from_tree (gsi
, new_rhs
);
1919 tree var
= TREE_OPERAND (TREE_OPERAND (new_rhs
, 0),0);
1921 insert_clobbers_for_var (*gsi
, var
);
1926 /* Propagate into the call arguments. Compared to replace_uses_in
1927 this can use the argument slot types for type verification
1928 instead of the current argument type. We also can safely
1929 drop qualifiers here as we are dealing with constants anyway. */
1930 argt
= TYPE_ARG_TYPES (gimple_call_fntype (stmt
));
1931 for (i
= 0; i
< gimple_call_num_args (stmt
) && argt
;
1932 ++i
, argt
= TREE_CHAIN (argt
))
1934 tree arg
= gimple_call_arg (stmt
, i
);
1935 if (TREE_CODE (arg
) == SSA_NAME
1936 && (val
= get_constant_value (arg
))
1937 && useless_type_conversion_p
1938 (TYPE_MAIN_VARIANT (TREE_VALUE (argt
)),
1939 TYPE_MAIN_VARIANT (TREE_TYPE (val
))))
1941 gimple_call_set_arg (stmt
, i
, unshare_expr (val
));
1951 tree lhs
= gimple_assign_lhs (stmt
);
1954 /* If we have a load that turned out to be constant replace it
1955 as we cannot propagate into all uses in all cases. */
1956 if (gimple_assign_single_p (stmt
)
1957 && TREE_CODE (lhs
) == SSA_NAME
1958 && (val
= get_constant_value (lhs
)))
1960 tree rhs
= unshare_expr (val
);
1961 if (!useless_type_conversion_p (TREE_TYPE (lhs
), TREE_TYPE (rhs
)))
1962 rhs
= fold_build1 (VIEW_CONVERT_EXPR
, TREE_TYPE (lhs
), rhs
);
1963 gimple_assign_set_rhs_from_tree (gsi
, rhs
);
1975 /* Visit the assignment statement STMT. Set the value of its LHS to the
1976 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
1977 creates virtual definitions, set the value of each new name to that
1978 of the RHS (if we can derive a constant out of the RHS).
1979 Value-returning call statements also perform an assignment, and
1980 are handled here. */
1982 static enum ssa_prop_result
1983 visit_assignment (gimple stmt
, tree
*output_p
)
1986 enum ssa_prop_result retval
;
1988 tree lhs
= gimple_get_lhs (stmt
);
1990 gcc_assert (gimple_code (stmt
) != GIMPLE_CALL
1991 || gimple_call_lhs (stmt
) != NULL_TREE
);
1993 if (gimple_assign_single_p (stmt
)
1994 && gimple_assign_rhs_code (stmt
) == SSA_NAME
)
1995 /* For a simple copy operation, we copy the lattice values. */
1996 val
= *get_value (gimple_assign_rhs1 (stmt
));
1998 /* Evaluate the statement, which could be
1999 either a GIMPLE_ASSIGN or a GIMPLE_CALL. */
2000 val
= evaluate_stmt (stmt
);
2002 retval
= SSA_PROP_NOT_INTERESTING
;
2004 /* Set the lattice value of the statement's output. */
2005 if (TREE_CODE (lhs
) == SSA_NAME
)
2007 /* If STMT is an assignment to an SSA_NAME, we only have one
2009 if (set_lattice_value (lhs
, val
))
2012 if (val
.lattice_val
== VARYING
)
2013 retval
= SSA_PROP_VARYING
;
2015 retval
= SSA_PROP_INTERESTING
;
2023 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
2024 if it can determine which edge will be taken. Otherwise, return
2025 SSA_PROP_VARYING. */
2027 static enum ssa_prop_result
2028 visit_cond_stmt (gimple stmt
, edge
*taken_edge_p
)
2033 block
= gimple_bb (stmt
);
2034 val
= evaluate_stmt (stmt
);
2035 if (val
.lattice_val
!= CONSTANT
2036 || !double_int_zero_p (val
.mask
))
2037 return SSA_PROP_VARYING
;
2039 /* Find which edge out of the conditional block will be taken and add it
2040 to the worklist. If no single edge can be determined statically,
2041 return SSA_PROP_VARYING to feed all the outgoing edges to the
2042 propagation engine. */
2043 *taken_edge_p
= find_taken_edge (block
, val
.value
);
2045 return SSA_PROP_INTERESTING
;
2047 return SSA_PROP_VARYING
;
2051 /* Evaluate statement STMT. If the statement produces an output value and
2052 its evaluation changes the lattice value of its output, return
2053 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
2056 If STMT is a conditional branch and we can determine its truth
2057 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
2058 value, return SSA_PROP_VARYING. */
2060 static enum ssa_prop_result
2061 ccp_visit_stmt (gimple stmt
, edge
*taken_edge_p
, tree
*output_p
)
2066 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2068 fprintf (dump_file
, "\nVisiting statement:\n");
2069 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2072 switch (gimple_code (stmt
))
2075 /* If the statement is an assignment that produces a single
2076 output value, evaluate its RHS to see if the lattice value of
2077 its output has changed. */
2078 return visit_assignment (stmt
, output_p
);
2081 /* A value-returning call also performs an assignment. */
2082 if (gimple_call_lhs (stmt
) != NULL_TREE
)
2083 return visit_assignment (stmt
, output_p
);
2088 /* If STMT is a conditional branch, see if we can determine
2089 which branch will be taken. */
2090 /* FIXME. It appears that we should be able to optimize
2091 computed GOTOs here as well. */
2092 return visit_cond_stmt (stmt
, taken_edge_p
);
2098 /* Any other kind of statement is not interesting for constant
2099 propagation and, therefore, not worth simulating. */
2100 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2101 fprintf (dump_file
, "No interesting values produced. Marked VARYING.\n");
2103 /* Definitions made by statements other than assignments to
2104 SSA_NAMEs represent unknown modifications to their outputs.
2105 Mark them VARYING. */
2106 FOR_EACH_SSA_TREE_OPERAND (def
, stmt
, iter
, SSA_OP_ALL_DEFS
)
2108 prop_value_t v
= { VARYING
, NULL_TREE
, { -1, (HOST_WIDE_INT
) -1 } };
2109 set_lattice_value (def
, v
);
2112 return SSA_PROP_VARYING
;
2116 /* Main entry point for SSA Conditional Constant Propagation. */
2121 unsigned int todo
= 0;
2122 calculate_dominance_info (CDI_DOMINATORS
);
2124 ssa_propagate (ccp_visit_stmt
, ccp_visit_phi_node
);
2125 if (ccp_finalize ())
2126 todo
= (TODO_cleanup_cfg
| TODO_update_ssa
| TODO_remove_unused_locals
);
2127 free_dominance_info (CDI_DOMINATORS
);
2135 return flag_tree_ccp
!= 0;
2139 struct gimple_opt_pass pass_ccp
=
2144 gate_ccp
, /* gate */
2145 do_ssa_ccp
, /* execute */
2148 0, /* static_pass_number */
2149 TV_TREE_CCP
, /* tv_id */
2150 PROP_cfg
| PROP_ssa
, /* properties_required */
2151 0, /* properties_provided */
2152 0, /* properties_destroyed */
2153 0, /* todo_flags_start */
2155 | TODO_verify_stmts
| TODO_ggc_collect
/* todo_flags_finish */
2161 /* Try to optimize out __builtin_stack_restore. Optimize it out
2162 if there is another __builtin_stack_restore in the same basic
2163 block and no calls or ASM_EXPRs are in between, or if this block's
2164 only outgoing edge is to EXIT_BLOCK and there are no calls or
2165 ASM_EXPRs after this __builtin_stack_restore. */
2168 optimize_stack_restore (gimple_stmt_iterator i
)
2173 basic_block bb
= gsi_bb (i
);
2174 gimple call
= gsi_stmt (i
);
2176 if (gimple_code (call
) != GIMPLE_CALL
2177 || gimple_call_num_args (call
) != 1
2178 || TREE_CODE (gimple_call_arg (call
, 0)) != SSA_NAME
2179 || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call
, 0))))
2182 for (gsi_next (&i
); !gsi_end_p (i
); gsi_next (&i
))
2184 stmt
= gsi_stmt (i
);
2185 if (gimple_code (stmt
) == GIMPLE_ASM
)
2187 if (gimple_code (stmt
) != GIMPLE_CALL
)
2190 callee
= gimple_call_fndecl (stmt
);
2192 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2193 /* All regular builtins are ok, just obviously not alloca. */
2194 || DECL_FUNCTION_CODE (callee
) == BUILT_IN_ALLOCA
2195 || DECL_FUNCTION_CODE (callee
) == BUILT_IN_ALLOCA_WITH_ALIGN
)
2198 if (DECL_FUNCTION_CODE (callee
) == BUILT_IN_STACK_RESTORE
)
2199 goto second_stack_restore
;
2205 /* Allow one successor of the exit block, or zero successors. */
2206 switch (EDGE_COUNT (bb
->succs
))
2211 if (single_succ_edge (bb
)->dest
!= EXIT_BLOCK_PTR
)
2217 second_stack_restore
:
2219 /* If there's exactly one use, then zap the call to __builtin_stack_save.
2220 If there are multiple uses, then the last one should remove the call.
2221 In any case, whether the call to __builtin_stack_save can be removed
2222 or not is irrelevant to removing the call to __builtin_stack_restore. */
2223 if (has_single_use (gimple_call_arg (call
, 0)))
2225 gimple stack_save
= SSA_NAME_DEF_STMT (gimple_call_arg (call
, 0));
2226 if (is_gimple_call (stack_save
))
2228 callee
= gimple_call_fndecl (stack_save
);
2230 && DECL_BUILT_IN_CLASS (callee
) == BUILT_IN_NORMAL
2231 && DECL_FUNCTION_CODE (callee
) == BUILT_IN_STACK_SAVE
)
2233 gimple_stmt_iterator stack_save_gsi
;
2236 stack_save_gsi
= gsi_for_stmt (stack_save
);
2237 rhs
= build_int_cst (TREE_TYPE (gimple_call_arg (call
, 0)), 0);
2238 update_call_from_tree (&stack_save_gsi
, rhs
);
2243 /* No effect, so the statement will be deleted. */
2244 return integer_zero_node
;
2247 /* If va_list type is a simple pointer and nothing special is needed,
2248 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
2249 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
2250 pointer assignment. */
2253 optimize_stdarg_builtin (gimple call
)
2255 tree callee
, lhs
, rhs
, cfun_va_list
;
2256 bool va_list_simple_ptr
;
2257 location_t loc
= gimple_location (call
);
2259 if (gimple_code (call
) != GIMPLE_CALL
)
2262 callee
= gimple_call_fndecl (call
);
2264 cfun_va_list
= targetm
.fn_abi_va_list (callee
);
2265 va_list_simple_ptr
= POINTER_TYPE_P (cfun_va_list
)
2266 && (TREE_TYPE (cfun_va_list
) == void_type_node
2267 || TREE_TYPE (cfun_va_list
) == char_type_node
);
2269 switch (DECL_FUNCTION_CODE (callee
))
2271 case BUILT_IN_VA_START
:
2272 if (!va_list_simple_ptr
2273 || targetm
.expand_builtin_va_start
!= NULL
2274 || !builtin_decl_explicit_p (BUILT_IN_NEXT_ARG
))
2277 if (gimple_call_num_args (call
) != 2)
2280 lhs
= gimple_call_arg (call
, 0);
2281 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2282 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2283 != TYPE_MAIN_VARIANT (cfun_va_list
))
2286 lhs
= build_fold_indirect_ref_loc (loc
, lhs
);
2287 rhs
= build_call_expr_loc (loc
, builtin_decl_explicit (BUILT_IN_NEXT_ARG
),
2288 1, integer_zero_node
);
2289 rhs
= fold_convert_loc (loc
, TREE_TYPE (lhs
), rhs
);
2290 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2292 case BUILT_IN_VA_COPY
:
2293 if (!va_list_simple_ptr
)
2296 if (gimple_call_num_args (call
) != 2)
2299 lhs
= gimple_call_arg (call
, 0);
2300 if (!POINTER_TYPE_P (TREE_TYPE (lhs
))
2301 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs
)))
2302 != TYPE_MAIN_VARIANT (cfun_va_list
))
2305 lhs
= build_fold_indirect_ref_loc (loc
, lhs
);
2306 rhs
= gimple_call_arg (call
, 1);
2307 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs
))
2308 != TYPE_MAIN_VARIANT (cfun_va_list
))
2311 rhs
= fold_convert_loc (loc
, TREE_TYPE (lhs
), rhs
);
2312 return build2 (MODIFY_EXPR
, TREE_TYPE (lhs
), lhs
, rhs
);
2314 case BUILT_IN_VA_END
:
2315 /* No effect, so the statement will be deleted. */
2316 return integer_zero_node
;
2323 /* Attemp to make the block of __builtin_unreachable I unreachable by changing
2324 the incoming jumps. Return true if at least one jump was changed. */
2327 optimize_unreachable (gimple_stmt_iterator i
)
2329 basic_block bb
= gsi_bb (i
);
2330 gimple_stmt_iterator gsi
;
2336 for (gsi
= gsi_start_bb (bb
); !gsi_end_p (gsi
); gsi_next (&gsi
))
2338 stmt
= gsi_stmt (gsi
);
2340 if (is_gimple_debug (stmt
))
2343 if (gimple_code (stmt
) == GIMPLE_LABEL
)
2345 /* Verify we do not need to preserve the label. */
2346 if (FORCED_LABEL (gimple_label_label (stmt
)))
2352 /* Only handle the case that __builtin_unreachable is the first statement
2353 in the block. We rely on DCE to remove stmts without side-effects
2354 before __builtin_unreachable. */
2355 if (gsi_stmt (gsi
) != gsi_stmt (i
))
2360 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
2362 gsi
= gsi_last_bb (e
->src
);
2363 if (gsi_end_p (gsi
))
2366 stmt
= gsi_stmt (gsi
);
2367 if (gimple_code (stmt
) == GIMPLE_COND
)
2369 if (e
->flags
& EDGE_TRUE_VALUE
)
2370 gimple_cond_make_false (stmt
);
2371 else if (e
->flags
& EDGE_FALSE_VALUE
)
2372 gimple_cond_make_true (stmt
);
2378 /* Todo: handle other cases, f.i. switch statement. */
2388 /* A simple pass that attempts to fold all builtin functions. This pass
2389 is run after we've propagated as many constants as we can. */
2392 execute_fold_all_builtins (void)
2394 bool cfg_changed
= false;
2396 unsigned int todoflags
= 0;
2400 gimple_stmt_iterator i
;
2401 for (i
= gsi_start_bb (bb
); !gsi_end_p (i
); )
2403 gimple stmt
, old_stmt
;
2404 tree callee
, result
;
2405 enum built_in_function fcode
;
2407 stmt
= gsi_stmt (i
);
2409 if (gimple_code (stmt
) != GIMPLE_CALL
)
2414 callee
= gimple_call_fndecl (stmt
);
2415 if (!callee
|| DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
)
2420 fcode
= DECL_FUNCTION_CODE (callee
);
2422 result
= gimple_fold_builtin (stmt
);
2425 gimple_remove_stmt_histograms (cfun
, stmt
);
2428 switch (DECL_FUNCTION_CODE (callee
))
2430 case BUILT_IN_CONSTANT_P
:
2431 /* Resolve __builtin_constant_p. If it hasn't been
2432 folded to integer_one_node by now, it's fairly
2433 certain that the value simply isn't constant. */
2434 result
= integer_zero_node
;
2437 case BUILT_IN_ASSUME_ALIGNED
:
2438 /* Remove __builtin_assume_aligned. */
2439 result
= gimple_call_arg (stmt
, 0);
2442 case BUILT_IN_STACK_RESTORE
:
2443 result
= optimize_stack_restore (i
);
2449 case BUILT_IN_UNREACHABLE
:
2450 if (optimize_unreachable (i
))
2454 case BUILT_IN_VA_START
:
2455 case BUILT_IN_VA_END
:
2456 case BUILT_IN_VA_COPY
:
2457 /* These shouldn't be folded before pass_stdarg. */
2458 result
= optimize_stdarg_builtin (stmt
);
2468 if (result
== NULL_TREE
)
2471 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2473 fprintf (dump_file
, "Simplified\n ");
2474 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2478 if (!update_call_from_tree (&i
, result
))
2480 gimplify_and_update_call_from_tree (&i
, result
);
2481 todoflags
|= TODO_update_address_taken
;
2484 stmt
= gsi_stmt (i
);
2487 if (maybe_clean_or_replace_eh_stmt (old_stmt
, stmt
)
2488 && gimple_purge_dead_eh_edges (bb
))
2491 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2493 fprintf (dump_file
, "to\n ");
2494 print_gimple_stmt (dump_file
, stmt
, 0, dump_flags
);
2495 fprintf (dump_file
, "\n");
2498 /* Retry the same statement if it changed into another
2499 builtin, there might be new opportunities now. */
2500 if (gimple_code (stmt
) != GIMPLE_CALL
)
2505 callee
= gimple_call_fndecl (stmt
);
2507 || DECL_BUILT_IN_CLASS (callee
) != BUILT_IN_NORMAL
2508 || DECL_FUNCTION_CODE (callee
) == fcode
)
2513 /* Delete unreachable blocks. */
2515 todoflags
|= TODO_cleanup_cfg
;
2521 struct gimple_opt_pass pass_fold_builtins
=
2527 execute_fold_all_builtins
, /* execute */
2530 0, /* static_pass_number */
2531 TV_NONE
, /* tv_id */
2532 PROP_cfg
| PROP_ssa
, /* properties_required */
2533 0, /* properties_provided */
2534 0, /* properties_destroyed */
2535 0, /* todo_flags_start */
2537 | TODO_update_ssa
/* todo_flags_finish */