RFR: 8330844: Add aliases for conditional jumps and additional instruction forms for x86 [v2]

[Vladimir Kozlov]

On Mon, 22 Apr 2024 20:47:52 GMT, Scott Gibbons <sgibbons at openjdk.org> wrote:

>> Adding infrastructure for JDK-8320448.  Aliasing conditional jump instructions; making arrays_equals accessible from stubs; adding some x86 instructions.
>
> Scott Gibbons has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Undo move of arrays_equals

Can you also remove changes in `arrays_equals` from this PR? It is fine to have them in JDK-8320448 changes.

src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp line 4503:

> 4501: 
> 4502:   assert((!expand_ary2) || ((expand_ary2) && (UseAVX == 2)),
> 4503:          "Expansion only implemented for AVX2");

BTW, the check in assert could be simplified: `(!expand_ary2 || UseAVX == 2)`

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PR Comment: https://git.openjdk.org/jdk/pull/18893#issuecomment-2070990618
PR Review Comment: https://git.openjdk.org/jdk/pull/18893#discussion_r1575383066