The load from *q should be CSEd but it isn't because tree forwprop introduces
a VIEW_CONVERT_EXPR from a load of p->f which conflicts with the store
through *r.
/* { dg-do "compile" } */
/* { dg-options "-O -fdump-tree-fre" } */
struct S { float f; };
int __attribute__((noinline))
foo (float *r, struct S *p)
{
int *q = (int *)&p->f;
int i = *q;
*r = 0.0;
return i + *q;
}
/* { dg-final { scan-tree-dump-times "\\\*q" 1 "fre" } } */
/* { dg-final { cleanup-tree-dump "fre" } } */
--
Summary: [4.4 Regression] Missed FRE because of VIEW_CONVERT_EXPR
Product: gcc
Version: 4.4.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: rguenth at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38748
