RFR: 8357551: RISC-V: support CMoveF/D vectorization [v2]

[Emanuel Peter]

On Fri, 14 Nov 2025 18:12:56 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> test/hotspot/jtreg/compiler/c2/irTests/TestScalarConditionalMove.java line 49:
>> 
>>> 47:                                    "-XX:+UnlockExperimentalVMOptions", "-XX:-UseCompactObjectHeaders");
>>> 48:         TestFramework.runWithFlags("-XX:+UseCMoveUnconditionally", "-XX:-UseVectorCmov",
>>> 49:                                    "-XX:+UnlockExperimentalVMOptions", "-XX:+UseCompactObjectHeaders");
>> 
>> Wait. Is this just a copy of the existing vector test, but run with CMove vectorization disabled?
>> If so, we could just add these additional runs to the existing test, and guard the IR test with corresponding flags:
>> Have an IR rule for `-XX:-UseVectorCmov` and one for `-XX:+UseVectorCmov`.
>> 
>> That would allow us to reduce some code duplication. And it would also avoid letting the two tests go out of sync when people add more to one but not the other.
>> 
>> What do you think?
>
> Good idea!
> I can do it. What do you think about the name of the merged tests? `TestConditionalMove.java` or `TestScalarAndVectorConditionalMove.java`

`TestConditionalMove.java` sounds good :)

It would also be nice if we could move it out of the `irTests` directory, we would like to eventually move all tests away from it, and rather sort the tests by what they test and not by how we test them. Though now it's a little tricky because we check for both vector and scalar things. Still, I would propose that you move it under `c2/vectorization` or `c2/loopopts/superword`, since they do include vectorization tests. An alternative could also be in a new `c2/cmove` directory.

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PR Review Comment: https://git.openjdk.org/jdk/pull/28309#discussion_r2533020809