[llvm] r177730 - R600: Use legacy (0 * anything = 0) MUL instructions for pow intrinsics

[Rafael Espíndola]

>> But for example for the last change of our ELSE pseudo operation I don't
>> even know how to cover that with llvm IR (except for adding compiled IR
>> output of piglit and that's something around 25kb in size and covering allot
>> of different things and not only that bug in specific).
>
>
> Testcase reduction is a well understood endeavor though. Sometimes it fails,
> but it is really important that you try everything you can to reduce and
> distill a minimal test case to cover these types of bugs. Otherwise, no one
> can maintain or update your backend with confidence.

In this case in particular we got a 1 line test case change: r177736,
which is quiet a bit better than 25kb.

Cheers,
Rafael