RFR: 8293488: Add EOR3 backend rule for aarch64 SHA3 extension [v5]

[Bhavana Kilambi]

On Tue, 29 Nov 2022 09:41:34 GMT, Nick Gasson <ngasson at openjdk.org> wrote:

>> Bhavana Kilambi has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains six commits:
>> 
>>  - Resolve merge conflicts with master
>>  - Merge branch 'master' into JDK-8293488
>>  - Removed svesha3 feature check for eor3
>>  - Changed the modifier order preference in JTREG test
>>  - Modified JTREG test to include feature constraints
>>  - 8293488: Add EOR3 backend rule for aarch64 SHA3 extension
>>    
>>    Arm ISA v8.2A and v9.0A include SHA3 feature extensions and one of those
>>    SHA3 instructions - "eor3" performs an exclusive OR of three vectors.
>>    This is helpful in applications that have multiple, consecutive "eor"
>>    operations which can be reduced by clubbing them into fewer operations
>>    using the "eor3" instruction. For example -
>>    eor a, a, b
>>    eor a, a, c
>>    can be optimized to single instruction - eor3 a, b, c
>>    
>>    This patch adds backend rules for Neon and SVE2 "eor3" instructions and
>>    a micro benchmark to assess the performance gains with this patch.
>>    Following are the results of the included micro benchmark on a 128-bit
>>    aarch64 machine that supports Neon, SVE2 and SHA3 features -
>>    
>>    Benchmark               gain
>>    TestEor3.test1Int       10.87%
>>    TestEor3.test1Long      8.84%
>>    TestEor3.test2Int       21.68%
>>    TestEor3.test2Long      21.04%
>>    
>>    The numbers shown are performance gains with using Neon eor3 instruction
>>    over the master branch that uses multiple "eor" instructions instead.
>>    Similar gains can be observed with the SVE2 "eor3" version as well since
>>    the "eor3" instruction is unpredicated and the machine under test uses a
>>    maximum vector width of 128 bits which makes the SVE2 code generation very
>>    similar to the one with Neon.
>
> test/hotspot/gtest/aarch64/aarch64-asmtest.py line 1043:
> 
>> 1041:                         [str(self.reg[i]) for i in range(1, self.numRegs)]))
>> 1042:     def astr(self):
>> 1043:         if self._name == "eor3":
> 
> Suggestion:
> 
>         firstArg = 0 if self._name == "eor3" else 1
>         formatStr = "%s%s" + ''.join([", %s" for i in range(firstArg, self.numRegs)])
> 
> 
> And similarly below.

Thank you for the suggestion. I made the suggested changes in the latest patch. Please review.

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PR: https://git.openjdk.org/jdk/pull/10407