RFR: 8300247: Harden C1 xchg on AArch64 and PPC

Wed Jan 18 14:56:11 UTC 2023

On Wed, 18 Jan 2023 10:07:04 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> In the C1 xchg operation, AArch64 and PPC don't deal well with the input register and output register being the same. In some new code, that can happen. This change aims at solving that issue.
>> 
>> As for AArch64, the xchg implementation in the macro assembler already deals well with the input and output register being the same. So we just need to remove an assert. As for the PPC implementation, @TheRealMDoerr has written a variation that uses a temp operand ensuring that they are not the same register.
>
> Marked as reviewed by aph (Reviewer).

Thanks for the review, @theRealAph!

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PR: https://git.openjdk.org/jdk/pull/12065