[PATCH] D14400: [SimplifyLibCalls] Tranform log(pow(x, y)) -> y*log(x)

[Davide Italiano via llvm-commits]

On Thu, Nov 5, 2015 at 4:17 PM, Davide Italiano via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> davide added a comment.
>
> In http://reviews.llvm.org/D14400#282851, @scanon wrote:
>
>> The one thing that's a little bit weird here is cases like x = -1, y = 4; log(pow(-1, 4)) is 0, but 4*log(-1) is NaN.  That's a dramatic difference even for fast-math.  Do we find exact integer exponents before we get to this point?
>
>
> Yes, that's a little bit unfortunate. I don't think we find exact exponents before we get to this point. Do you think it's a showstopper to get this patch into the tree? By the way, I also noticed gcc produces the same very ouput on your testcase, for what it's worth.
>
>

Hi Steven,
any further comments on this (and D14466?)

Thanks,

-- 
Davide

"There are no solved problems; there are only problems that are more
or less solved" -- Henri Poincare