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Re: VRP: normalize VR_VARYING in PLUS/MINUS_EXPR handling
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: Aldy Hernandez <aldyh at redhat dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Fri, 14 Sep 2018 09:14:21 +0200
- Subject: Re: VRP: normalize VR_VARYING in PLUS/MINUS_EXPR handling
- References: <d5cea256-62d2-3576-480e-6902e378861a@redhat.com>
On Tue, Sep 11, 2018 at 12:34 PM Aldy Hernandez <aldyh@redhat.com> wrote:
>
> For addition and subtraction, we're currently punting on things like
> [0,0] - VR_VARYING. However, if we normalize VR_VARYING to the entire
> domain, we can see that the above is actually [-MIN+1, +MAX].
>
> We would've normally caught this sort of things with my rewrite of the
> binary operators, but PLUS/MINUS are special in that they're pretty much
> the only operator that keeps symbolics through it's calculations. This
> is why we can't just blindly treat symbolics as [-MIN, +MAX] as I've
> done elsewhere. PLUS/MINUS are handled specially (ugly) :-/.
>
> OK for trunk?
OK.
>