RFR: 8310886: C2 SuperWord: Two nodes should be isomorphic if they are loop invariant but pinned at different nodes outside the loop [v2]

[Christian Hagedorn]

On Wed, 20 Sep 2023 18:50:52 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> Are you sure that VNNI instruction is used in your test? I don't see VNNI CPU feature check in the test. Here is instruction: https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/x86/x86.ad#L8744

You're right - I'm currently only checking if Superword succeeds and creates `MulAddVS2VINodes` but not if the matcher also matches `vmuladdaddS2I_reg` when VNNI is supported. I've pushed an update to add an additional IR rule which checks that `vmuladdaddS2I_reg` is matched (i.e. the mach graph contains this node) if VNNI is available.

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PR Comment: https://git.openjdk.org/jdk/pull/15842#issuecomment-1729081869