Re: CRC32C Parallel Computation Optimization on ARM

On Fri, Oct 27, 2023 at 07:01:10AM +0000, Xiang Gao wrote:
> On Thu, 26 Oct, 2023 11:37:52AM -0500, Nathan Bossart wrote:
>>> We consider that a runtime check needs to be done in any scenario.
>>> Here we only confirm that the compilation can be successful.
>> >A runtime check will be done when choosing which algorithm.
>> >You can think of us as merging USE_ARMV8_VMULL and USE_ARMV8_VMULL_WITH_RUNTIME_CHECK into USE_ARMV8_VMULL.
> 
>>Oh.  Looking again, I see that we are using a runtime check for ARM in all
>>cases with this patch.  If so, maybe we should just remove
>>USE_ARV8_CRC32C_WITH_RUNTIME_CHECK in a prerequisite patch (and have
>>USE_ARMV8_CRC32C always do the runtime check).  I suspect there are other
>>opportunities to simplify things, too.
> 
> Yes, I have been removed USE_ARMV8_CRC32C_WITH_RUNTIME_CHECK in this patch.

Thanks.  I went ahead and split this prerequisite part out to a separate
thread [0] since it's sort-of unrelated to your proposal here.  It's not
really a prerequisite, but I do think it will simplify things a bit.

[0] https://postgr.es/m/20231030161706.GA3011%40nathanxps13

-- 
Nathan Bossart
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