[llvm] r236894 - [BasicAA] Fix zext & sext handling

[Hans Wennborg]

On Fri, May 8, 2015 at 11:58 AM, Sanjoy Das
<sanjoy at playingwithpointers.com> wrote:
> Author: sanjoy
> Date: Fri May  8 13:58:55 2015
> New Revision: 236894
>
> URL: http://llvm.org/viewvc/llvm-project?rev=236894&view=rev
> Log:
> [BasicAA] Fix zext & sext handling
>
> Summary:
>
> There are several unhandled edge cases in BasicAA's GetLinearExpression
> method. This changes fixes outstanding issues, including zext / sext of
> a constant with the sign bit set, and the refusal to decompose zexts or
> sexts of wrapping arithmetic.
>
> Test Plan: Unit tests added in //q.ext.ll//.

This seems to have caused PR23626. I've reverted it in r237984.

 - Hans