Integrated: 8268858: Determine register pressure automatically by the number of available registers for allocation

[Joshua Zhu]

On Wed, 16 Jun 2021 04:20:31 GMT, Joshua Zhu <jzhu at openjdk.org> wrote:

> Hi,
> 
> This patch includes the following changes:
> 
> 1) Determine register pressure automatically by the number of available
>    registers for allocation.
>    Currently, INTPRESSURE is hard-coded no matter whether heapbase
>    or framepointer register is available for RA.
> 
> 2) x86: Machines with AVX3 have 2x more XMM registers.
>         The pressure threshold should be improved for both RA and LCM.
>         Currently, only scheduling takes more XMM registers into
>         consideration.
> 
> 3) aarch64: add a new jtreg case
>         In bug 8183543, this case caused many compilation failures with
>         "failed spill-split-recycle sanity check". This test case is
>         imported to ensure no regression failure.
> 
> Inconsistent pressure threshold value with the number of available
> registers will bring unnecessary spilling in some scenarios.
> I wrote a simple example as one case:
>   https://cr.openjdk.java.net/~jzhu/8268858/Test.java
> 
> With this patch, 4 extra spill copies are eliminated on AArch64.
>   old OptoAssembly: https://cr.openjdk.java.net/~jzhu/8268858/old_opto_assembly
>   new OptoAssembly: https://cr.openjdk.java.net/~jzhu/8268858/new_opto_assembly
> 
> Could you please help review this patch?
> 
> Best Regards,
> Joshua

This pull request has now been integrated.

Changeset: 36d82b6e
Author:    Joshua Zhu <jzhu at openjdk.org>
Committer: Yi Yang <yyang at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/36d82b6ef18d8add5f97fad507b7d86d702bdf13
Stats:     238 lines in 20 files changed: 173 ins; 44 del; 21 mod

8268858: Determine register pressure automatically by the number of available registers for allocation

Reviewed-by: kvn, dlong

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PR: https://git.openjdk.java.net/jdk/pull/4505