Re: [PATCH] SVE popcount support

Chiranmoy.Bhattacharya@fujitsu.com <chiranmoy.bhattacharya@fujitsu.com>

From: "Chiranmoy.Bhattacharya@fujitsu.com" <Chiranmoy.Bhattacharya@fujitsu.com>

To: Nathan Bossart <nathandbossart@gmail.com>

Cc: "Malladi, Rama" <ramamalladi@hotmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, "Ragesh.Hajela@fujitsu.com" <Ragesh.Hajela@fujitsu.com>, Salvatore Dipietro <dipiets@amazon.com>, "Devanga.Susmitha@fujitsu.com" <Devanga.Susmitha@fujitsu.com>

Date: 2025-02-19T09:31:50Z

Lists: pgsql-hackers

Commits

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Optimize popcount functions with ARM SVE intrinsics.
- 519338ace410 18.0 landed
Optimize popcount functions with ARM Neon intrinsics.
- 6be53c27673a 18.0 landed
Rename TRY_POPCNT_FAST to TRY_POPCNT_X86_64.
- 9ac6f7e7ceb6 18.0 landed

Attachments

v5-0001-SVE-support-for-popcount-and-popcount-masked.patch (application/octet-stream) patch v5-0001

> Hm.  Any idea why that is?  I wonder if the compiler isn't using as many
> SVE registers as it could for this.

Not sure, we tried forcing loop unrolling using the below line in the MakeFile
but the results are the same.

pg_popcount_sve.o: CFLAGS += ${CFLAGS_UNROLL_LOOPS} -march=native


> I've also noticed that the latest patch doesn't compile on my M3 macOS
> machine.  After a quick glance, I think the problem is that the
> TRY_POPCNT_FAST macro is set, so it's trying to compile the assembly
> versions.

Fixed, we tried using the existing "choose" logic guarded by TRY_POPCNT_FAST.
The latest patch bypasses TRY_POPCNT_FAST by having a separate choose logic
for aarch64.


-Chiranmoy