RFR: 8318220: RISC-V: C2 ReverseI

[Fei Yang]

On Wed, 12 Mar 2025 10:26:58 GMT, Hamlin Li <mli at openjdk.org> wrote:

> Interesting question. `srli` will also result 0x80000000 which is a int of -2147483648, I think the question could be translated to something like, "do we need to sign-extend the result?" I think the answer should be YES, so you're right. 

Yes, that's exactly what I mean. We should have a 32-bit sign-exention here.

> I'm thinking how to construct a test so that the current implementation fails. `long l = Integer.reverse(i)` could be a solution.

Yeah, maybe. It won't menifest if you simply store the 32-bit result of reversing back into the array as the current test does. The reloading of this signed 32-bit value would sign-extend, thus hiding the issue when checking the result.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23963#discussion_r1991177879