RFR: 8357981: [PPC64] Remove old instructions from VM_Version::determine_features()
Martin Doerr
mdoerr at openjdk.org
Mon Jun 2 09:23:56 UTC 2025
On Wed, 28 May 2025 14:31:40 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:
> Simple cleanup after [JDK-8331859](https://bugs.openjdk.org/browse/JDK-8331859). The old instructions are always available and don't need to be tried in `VM_Version::determine_features()`.
>
> On Power10:
>
> --------------------------------------------------------------------------------
> Decoding cpu-feature detection stub at 0x000079b9203c0380 after execution:
> --------------------------------------------------------------------------------
> 0x000079b9203c0380: darn r7,1
> 0x000079b9203c0384: brw r5,r6
> 0x000079b9203c0388: blr bo=0b10100,bh=0b00[subroutine_return]
> 0x000079b9203c038c: dcbz 0,r3
> 0x000079b9203c0390: blr bo=0b10100,bh=0b00[subroutine_return]
>
>
> Also tested on older processors: On Power9, `brw` gets zeroed out. On Power8, `darn` also gets zeroed out.
Thanks for the reviews!
-------------
PR Comment: https://git.openjdk.org/jdk/pull/25495#issuecomment-2929629790
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