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re PR tree-optimization/22591 (wrong alias information causes an incorrect redundant load elimination)

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PR 22591
	* tree-ssa-alias.c (may_alias_p): Remove shortcut that tests
	whether a pointer of type T * may point to objects of type T *.

testsuite/ChangeLog

	PR 22591
	* gcc.dg/tree-ssa/pr22591.c: New test.
	* gcc.dg/tree-ssa/20030807-7.c: XFAIL everywhere.

From-SVN: r102393
This commit is contained in:
Diego Novillo 2005-07-26 19:53:54 +00:00 committed by Diego Novillo
parent 4549941152
commit 31521cd4e2
5 changed files with 69 additions and 18 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2005-07-26 Diego Novillo <dnovillo@redhat.com>
PR 22591
* tree-ssa-alias.c (may_alias_p): Remove shortcut that tests
whether a pointer of type T * may point to objects of type T *.
2005-07-26 DJ Delorie <dj@redhat.com>
* configure: Regenerate.

6
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,9 @@
2005-07-26 Diego Novillo <dnovillo@redhat.com>
PR 22591
* gcc.dg/tree-ssa/pr22591.c: New test.
* gcc.dg/tree-ssa/20030807-7.c: XFAIL everywhere.
2005-07-26 Andrew Pinski <pinskia@physics.uc.edu>
PR libobjc/22606

2
gcc/testsuite/gcc.dg/tree-ssa/20030807-7.c
View File

@ -34,5 +34,5 @@ simplify_condition (cond_p)
/* There should be exactly one IF conditional. TBAA is not able to
determine that 'decl' and 'cond' can't alias. */
/* { dg-final { scan-tree-dump-times "if " 1 "dom3"} } */
/* { dg-final { scan-tree-dump-times "if " 1 "dom3" { xfail *-*-* } } } */
/* { dg-final { cleanup-tree-dump "dom3" } } */

56
gcc/testsuite/gcc.dg/tree-ssa/pr22591.c Normal file
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@ -0,0 +1,56 @@
/* { dg-do run } */
/* { dg-options "-O2" } */
void abort ();
typedef struct _Node
{
struct _Node *next, *prev;
} Node;
void __attribute__ ((noinline)) append (Node * q, Node * p)
{
p->next = q;
p->prev = q;
q->next = p;
q->prev = p;
}
inline void
swap (Node ** a, Node ** b)
{
Node *tmp = *a;
*a = *b;
*b = tmp;
}
/* Miscompilation seems to happen here. If one removes the if condition
(which should be true) the program works fine. */
void
ListSwap (Node * x, Node * y)
{
Node *tmp;
if (x->next)
{
swap (&x->next, &y->next);
swap (&x->prev, &y->prev);
x->next->prev = x->prev->next = x;
y->next->prev = y->prev->next = y;
}
}
int
main ()
{
Node A, A1, B, B1;
append (&A, &A1);
append (&B, &B1);
ListSwap (&A, &B);
if (&A != A.next->prev)
abort ();
return 0;
}

17
gcc/tree-ssa-alias.c
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@ -1511,23 +1511,6 @@ may_alias_p (tree ptr, HOST_WIDE_INT mem_alias_set,
alias_stats.tbaa_queries++;
/* If VAR is a pointer with the same alias set as PTR, then dereferencing
PTR can't possibly affect VAR. Note, that we are specifically testing
for PTR's alias set here, not its pointed-to type. We also can't
do this check with relaxed aliasing enabled. */
if (POINTER_TYPE_P (TREE_TYPE (var))
&& var_alias_set != 0
&& mem_alias_set != 0)
{
HOST_WIDE_INT ptr_alias_set = get_alias_set (ptr);
if (ptr_alias_set == var_alias_set)
{
alias_stats.alias_noalias++;
alias_stats.tbaa_resolved++;
return false;
}
}
/* If the alias sets don't conflict then MEM cannot alias VAR. */
if (!alias_sets_conflict_p (mem_alias_set, var_alias_set))
{