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fold-const.c (fold_binary): When comparing two simple ADDR_EXPR expressions...

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* fold-const.c (fold_binary): When comparing two simple ADDR_EXPR
        expressions, test their _DECL operands for pointer equality rather
        than using operand_equal_p.

        * gcc.dg/tree-ssa/pr22321.c: New test.

From-SVN: r101974
This commit is contained in:
Jeff Law 2005-07-13 10:31:23 -06:00 committed by Jeff Law
parent 4969c0d82c
commit 59f7a2023f
4 changed files with 47 additions and 3 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2005-07-13 Jeff Law <law@redhat.com>
* fold-const.c (fold_binary): When comparing two simple ADDR_EXPR
expressions, test their _DECL operands for pointer equality rather
than using operand_equal_p.
2005-07-13 H.J. Lu <hongjiu.lu@intel.com>
* config/alpha/linux.h (TARGET_HAS_F_SETLKW): Renamed to ...

20
gcc/fold-const.c
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@ -8757,9 +8757,23 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
&& ! lookup_attribute ("alias",
DECL_ATTRIBUTES (TREE_OPERAND (arg1, 0)))
&& ! DECL_EXTERNAL (TREE_OPERAND (arg1, 0)))
return constant_boolean_node (operand_equal_p (arg0, arg1, 0)
? code == EQ_EXPR : code != EQ_EXPR,
type);
{
/* We know that we're looking at the address of two
non-weak, unaliased, static _DECL nodes.
It is both wasteful and incorrect to call operand_equal_p
to compare the two ADDR_EXPR nodes. It is wasteful in that
all we need to do is test pointer equality for the arguments
to the two ADDR_EXPR nodes. It is incorrect to use
operand_equal_p as that function is NOT equivalent to a
C equality test. It can in fact return false for two
objects which would test as equal using the C equality
operator. */
bool equal = TREE_OPERAND (arg0, 0) == TREE_OPERAND (arg1, 0);
return constant_boolean_node (equal
? code == EQ_EXPR : code != EQ_EXPR,
type);
}
/* If this is a comparison of two exprs that look like an
ARRAY_REF of the same object, then we can fold this to a

4
gcc/testsuite/ChangeLog
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@ -1,3 +1,7 @@
2005-07-13 Jeff Law <law@redhat.com>
* gcc.dg/tree-ssa/pr22321.c: New test
2005-07-13 Paolo Bonzini <bonzini@gnu.org>
PR tree-optimization/21921

20
gcc/testsuite/gcc.dg/tree-ssa/pr22321.c Normal file
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@ -0,0 +1,20 @@
/* { dg-do compile } */
/* { dg-options "-O1 -fno-tree-vrp -fno-tree-copy-prop -fno-tree-ccp -fdump-tree-optimized" } */
volatile int x;
int main ()
{
volatile int *vip;
vip = &x;
volatile int *cvip;
cvip = vip;
if (vip != cvip) return -1;
return 0;
}
/* { dg-final { scan-tree-dump-times "return 0" 1 "optimized" } } */
/* { dg-final { cleanup-tree-dump "optimized" } } */