[lilliput-jdk17u:lilliput] Integrated: 8308172: [Lilliput/JDK17] Revert disabling vzeroupper

[Roman Kennke]

On Tue, 16 May 2023 10:57:52 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

> While looking through the diff between Lilliput/JDK17 and upstream JDK17, I noticed one change in library_call.cpp that should not be there, it probably slipped through from debugging.
> 
>         void clear_upper_avx() {
>       #ifdef X86
>     -     if (UseAVX >= 2) {
>     +     if (false && UseAVX >= 2) {
>             C->set_clear_upper_avx(true);
>           }
>       #endif
>         }
>  
> This prevents emitting vzeroupper instructions on x86_64. I believe this will have performance impact when transitioning between AVX and SSE code. We should revert this.

This pull request has now been integrated.

Changeset: a7a8efbd
Author:    Roman Kennke <rkennke at openjdk.org>
URL:       https://git.openjdk.org/lilliput-jdk17u/commit/a7a8efbdaa7daad48ae2a04eaf44fb70d27f8baf
Stats:     1 line in 1 file changed: 0 ins; 0 del; 1 mod

8308172: [Lilliput/JDK17] Revert disabling vzeroupper

Reviewed-by: shade

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PR: https://git.openjdk.org/lilliput-jdk17u/pull/18