Re: [PATCH, PR68640] Clear restrict in install_var_field

[Tom de Vries <Tom_deVries at mentor dot com>]

On 08/12/15 10:22, Richard Biener wrote:
> On Tue, 8 Dec 2015, Jakub Jelinek wrote:
>
> > On Tue, Dec 08, 2015 at 09:49:49AM +0100, Tom de Vries wrote:
> > > diff --git a/gcc/omp-low.c b/gcc/omp-low.c
> > > index d1d1e3c..ac4a94d 100644
> > > --- a/gcc/omp-low.c
> > > +++ b/gcc/omp-low.c
> > > @@ -1389,6 +1389,12 @@ install_var_field (tree var, bool by_ref, int mask, omp_context *ctx,
> > >   	      || !is_gimple_omp_oacc (ctx->stmt));
> > >
> > >     type = TREE_TYPE (var);
> > > +  /* Prevent redeclaring the var in the split-off function with a restrict
> > > +     pointer type.  Note that we only clear type itself, restrict qualifiers in
> > > +     the pointed-to type will be ignored by points-to analysis.  */
> > > +  if (POINTER_TYPE_P (type))
> > > +    type = build_qualified_type (type, TYPE_QUALS (type) & ~TYPE_QUAL_RESTRICT);
> >
> > Is it necessary to call build_qualified_type in the common case (when it is
> > not restrict)?  I'd think if (POINTER_TYPE_P (type) && TYPE_RESTRICT (type))
> > might be better.

Will do.

> > That said, I forgot when exactly are the cliques computed, it would be nice
> > if then computing those and seeing a
> > GOMP_parallel/GOACC_parallel_keyed/GOMP_target_ext/GOMP_task/GOMP_taskloop*
> > builtins we would just continue walking the outlined functions they refer to
> > as if it was a part of the current function for the purpose of the restrict
> > computation.
>
> Cliques are not computed in IPA PTA and the above would require IPA.

FTR, this is a generic (not openmp-related) example, and AFAIU a more 
generic form of the issue that is being raised.
...
static void __attribute__((noinline, noclone))
bar (int *a, int * b)
{
  *a = 1;
  *b = 2;
  *a = *a + 1;
}

void
foo (int *__restrict__ a, int *__restrict__ b)
{
  bar (a, b);
}
...

Thanks,
- Tom