Re: Fix PR85726 (div-div suboptimization) and a rant on match.pd :s-flag

[Jakub Jelinek <jakub at redhat dot com>]

On Thu, May 10, 2018 at 01:51:29PM +0200, Marc Glisse wrote:
> > > There are probably more
> > > complicated transformations this disables.
> > 
> > I'm providing an example from *real* code where the
> > transformation is bad (admittedly just for the div-div case).

Isn't the case of the posted real-world testcase that many targets have
instructions that can do division and modulo at the same time?
So perhaps don't punt just because of !single_use (), but punt if
!single_use () and one of the other uses is a modulo with the same constant
as the second division, or perhaps similarly if the first division is
!accompanied by modulo with the same constant too?

	Jakub