RFR(XS): 8171092: C1's Math.fma() intrinsic doesn't correctly process its inputs

[Vladimir Kozlov]

Looks good. When jdk9/hs is open for pushes I will sponsor it.

Thanks,
Vladimir

On 12/12/16 6:32 AM, Roland Westrelin wrote:
>
> http://cr.openjdk.java.net/~roland/8171092/webrev.00/
>
> 3rd input of the fma intrinsic is processed as a temp but is actually an
> input. The test case triggers the problem on aarch64 (with the patch
> from 8162338). I couldn't get a failure on x86 because the input is
> overwritten by the fma instruction: a copy of the input is made to a new
> register right before the fma instruction and the input is live until
> right before the fma instruction. I'm far from certain the bug cannot
> show up on x86 with some other code pattern.
>
> Roland.
>