On Tue, 31 May 2016, Marek Polacek wrote:
> > diff --git gcc/testsuite/c-c++-common/attr-may-alias-1.c
> > gcc/testsuite/c-c++-common/attr-may-alias-1.c
> > index e69de29..978b9a5 100644
> > --- gcc/testsuite/c-c++-common/attr-may-alias-1.c
> > +++ gcc/testsuite/c-c++-common/attr-may-alias-1.c
> > @@ -0,0 +1,26 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-O2 -Wall" } */
> > +
> > +typedef int T __attribute__((may_alias));
> > +
> > +extern T *p;
> > +extern int *p;
> > +
> > +extern int *p2;
> > +extern T *p2;
> > +
> > +void fn1 (T);
> > +void fn1 (int);
> > +
> > +void fn2 (int);
> > +void fn2 (T);
> > +
> > +/* Ensure that the composite types have may_alias. */
> > +void
> > +f (long *i)
> > +{
> > + *i = *(__typeof (*p) *) &p;
> > + asm ("" : : "r" (*p));
> > + *i = *(__typeof (*p2) *) &p2;
> > + asm ("" : : "r" (*p2));
I don't see how this test is supposed to verify properties of the
composite type. I'd expect you to need to verify that something does not
get optimized away, that would get optimized away in the absence of
may_alias.
--
Joseph S. Myers
jos...@codesourcery.com
