RFR: 8268858: Determine register pressure automatically by the number of available registers for allocation [v2]
Joshua Zhu
jzhu at openjdk.java.net
Mon Jun 21 07:58:13 UTC 2021
> 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
Joshua Zhu has updated the pull request incrementally with one additional commit since the last revision:
Update comments and place test into proper location
-------------
Changes:
- all: https://git.openjdk.java.net/jdk/pull/4505/files
- new: https://git.openjdk.java.net/jdk/pull/4505/files/fb381002..704b468b
Webrevs:
- full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4505&range=01
- incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4505&range=00-01
Stats: 169 lines in 4 files changed: 85 ins; 79 del; 5 mod
Patch: https://git.openjdk.java.net/jdk/pull/4505.diff
Fetch: git fetch https://git.openjdk.java.net/jdk pull/4505/head:pull/4505
PR: https://git.openjdk.java.net/jdk/pull/4505
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