RFR: 8297417: Poly1305IntrinsicFuzzTest fails with tag mismatch exception

[Volodymyr Paprotski]

On Wed, 23 Nov 2022 18:41:18 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

> Also, `-XX:+ForceUnreachable` is designed to stress non-rip addressing mode. Worth adding it to the corresponding test.

Thanks, was wondering about that.

> It's a general problem: it's hard to see possible interference when names alias to the same register. I suggest to get rid of `rscratch` declaration and directly refer to `t1` followed by `/*rscratch*/` comment:

Hmm. I think register aliasing is pretty much a 'necessary evil' in the intrinsic code. Having better names for variables combined with too few registers leads to this issue. (unless of course we could somehow inject intrinsics _before_ register_ allocation. Writing assembler with infinite registers.. there is an idea :) ) . 

But in this specific case maybe getting rid of aliasing doesn't harm the readability that much. In some way, I would had preferred to keep `rscratch` instead of `t1` (I already have too many 'temps') but the `/*rscratch*/` comment should make things ok. 👍

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PR: https://git.openjdk.org/jdk/pull/11308