Integrated: 8358013: [PPC64] VSX has poor performance on Power8

Martin Doerr mdoerr at openjdk.org
Tue Jun 3 09:27:07 UTC 2025


On Wed, 28 May 2025 22:23:57 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

> Power8 only has limited VSX instructions for the superword optimization and the Vector API and the performance is bad. Let's only use it on Power9 and newer by default. This change excludes the VSX registers from C2 register allocation for Power8. VSX instruction usage gets limited to a few places like intrinsics.
> 
> Note: Power8 is an old processor and performance optimizations for it are no longer planned.

This pull request has now been integrated.

Changeset: 457d9de8
Author:    Martin Doerr <mdoerr at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/457d9de81d0f65455e3292fafea03f0e83184029
Stats:     14 lines in 4 files changed: 10 ins; 0 del; 4 mod

8358013: [PPC64] VSX has poor performance on Power8

Reviewed-by: dbriemann, clanger

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PR: https://git.openjdk.org/jdk/pull/25514


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