Re: Let tree_single_nonzero_warnv_p use VRP

[Marc Glisse <marc dot glisse at inria dot fr>]

On Mon, 24 Apr 2017, Jakub Jelinek wrote:

> On Mon, Apr 24, 2017 at 09:41:01AM +0200, Richard Biener wrote:
> > On Sun, Apr 23, 2017 at 11:38 PM, Marc Glisse <marc.glisse@inria.fr> wrote:
> > > Hello,
> > >
> > > this patches teaches tree_expr_nonzero_warnv_p to handle SSA_NAME using
> > > range information and known (non-)zero bits, by delegating to
> > > expr_not_equal_to which already knows how to handle all that.
> > >
> > > This makes one strict overflow warning disappear. It isn't particularly
> > > surprising, since the new code makes tree_expr_nonzero_warnv_p return true
> > > without warning (we do not remember if the range information was obtained
> > > using strict overflow). In my opinion, improving code generation is more
> > > important than this specific warning.
> > >
> > > Bootstrap+regtest on powerpc64le-unknown-linux-gnu.
> >
> > Hmm, I think you need to guard this with a INTEGRAL_TYPE_P check
> > given the comment on tree_single_nonzero_warnv_p also talks about
> > FP.

The SSA_NAME case in expr_not_equal_to starts with

      if (!INTEGRAL_TYPE_P (TREE_TYPE (t)))
        return false;

Do you still want the extra check in tree_single_nonzero_warnv_p before 
calling expr_not_equal_to?

> I vaguely remember there were issues with that, because VRP uses
> the *_nonzero_warnv* functions to compute the ranges and now those
> functions would use range info.  But it has been some time ago and maybe this
> patch is different enough from what I've been trying back then.

I hope it is safe, but we'll see.

> So just please watch carefully for any fallout.

Ok.

--
Marc Glisse