On Wed, Apr 20, 2016 at 11:04:08AM +0200, Richard Biener wrote:
> > --- gcc/tree-if-conv.c
> > +++ gcc/tree-if-conv.c
> > @@ -262,6 +262,16 @@ ifc_temp_var (tree type, tree expr,
> > gimple_stmt_iterator *gsi)
> > return new_name;
> > }
> >
> > +/* Return true when COND is a false predicate. */
> > +
> > +static inline bool
> > +is_false_predicate (tree cond)
> > +{
> > + return (cond == NULL_TREE
> > + || cond == boolean_false_node
> > + || integer_zerop (cond));
> > +}
> > +
Is it really a good idea to return true even for cond == NULL_TREE?
I mean it is then very confusing, because both is_true_predicate and
is_false_predicate are true in that case.
It doesn't make a difference when both are used in ||, but looks really
weird and makes the occassional reader wonder if NULL_TREE is valid there at
all and what exactly it means.
> > /* Return true when COND is a true predicate. */
> >
> > static inline bool
> > @@ -1988,7 +1998,7 @@ predicate_mem_writes (loop_p loop)
> > gimple *stmt;
> > int index;
> >
> > - if (is_true_predicate (cond))
> > + if (is_true_predicate (cond) || is_false_predicate (cond))
> > continue;
> >
> > swap = false;
> >
> > Marek
Jakub
