[PATCH] Remove seemingly dead InstCombine compare code

[Eli Friedman]

On Thu, Aug 1, 2013 at 1:34 PM, Matt Arsenault
<Matthew.Arsenault at amd.com> wrote:
> Turn check / insert cast into assertions that the sizes are the same. Add some more tests to try to break it. These paths seemed to not be tested with a datalayout. This checks if it needs to cast GEP indices, but at this point they should have already been converted to the pointer sized integer.
>
>
> http://llvm-reviews.chandlerc.com/D1261
>
> Files:
>   lib/Transforms/InstCombine/InstCombineCompares.cpp
>   test/Transforms/InstCombine/getelementptr.ll
>   test/Transforms/InstCombine/icmp.ll
>   test/Transforms/InstCombine/load-cmp.ll

I'm pretty sure this patch is wrong.  instcombine will always
eventually transform GEPs in the way you expect, and in trivial cases,
we will visit the GEP before the icmp, but I think we can visit the
icmp first in more complicated cases.

-Eli