Integrated: 8260501: [Vector API] Improve register usage for shift operations on x86

[Jie Fu]

On Wed, 27 Jan 2021 11:52:54 GMT, Jie Fu <jiefu at openjdk.org> wrote:

> Hi all,
> 
> I found the register usage is less optimized for some shift operations.
> For example, vshiftL_imm [1]/vshiftI_imm require dst != src.
> But it's actually fine for the register allocator to assign dst == src.
> 
> Also, vshiftL [2]/vshiftI/vshiftS require dst != src.
> But it's actually required for UseAVX==0 only.
> For the most common cases (UseAVX > 0), it's fine to assign dst == src.
> 
> The fix splits vshiftS/vshiftI/vshiftL into UseAVX > 0 and UseAVX == 0 cases.
> And just removes the unreasonable requirement for vshiftI_imm and vshiftL_imm. 
> 
> Testing:
>   - jdk/incubator/vector/ on x64 with UseAVX=3/2/1/0, no regression
> 
> Thanks.
> Best regards,
> Jie
> 
> [1] https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/x86/x86.ad#L6058
> [2] https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/x86/x86.ad#L6037

This pull request has now been integrated.

Changeset: 0da9cad5
Author:    Jie Fu <jiefu at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/0da9cad5
Stats:     2 lines in 1 file changed: 0 ins; 2 del; 0 mod

8260501: [Vector API] Improve register usage for shift operations on x86

Reviewed-by: vlivanov, kvn

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PR: https://git.openjdk.java.net/jdk/pull/2257