[patch] Import various range-op fixes from the ranger branch.

[Andrew MacLeod]

On 10/5/20 11:19 AM, Aldy Hernandez wrote:
> This patch imports three fixes from the ranger branch:
>
> 1. Fold division by zero into varying instead of undefined.
> This provides compatibility with existing stuff on trunk.
>
> 2. Solver changes for lshift and rshift.
> This should not affect anything on trunk, as it only involves
> the GORI solver which is yet to be contributed.
>
> 3. Preserve existing behavior for ABS([-MIN,-MIN]).
> This is actually unrepresentable, but trunk has traditionally
> treated this as [-MIN,-MIN] so this patch just syncs range-ops
> with the rest of trunk.
>
> Approved off-line by Andrew.
>
> I will commit once tests finish.
>
> Aldy
>
> gcc/ChangeLog:
>
>
OK with an actual ChangeLog.

Andrew