RE: CRC32C Parallel Computation Optimization on ARM - Mailing list pgsql-hackers

From Xiang Gao
Subject RE: CRC32C Parallel Computation Optimization on ARM
Date
Msg-id DB9PR08MB6991A219E08040AC8D4159B8F5BAA@DB9PR08MB6991.eurprd08.prod.outlook.com
Whole thread Raw
In response to Re: CRC32C Parallel Computation Optimization on ARM  (Nathan Bossart <nathandbossart@gmail.com>)
Responses Re: CRC32C Parallel Computation Optimization on ARM
List pgsql-hackers
On Date: Fri, 10 Nov 2023 10:36:08AM -0600, Nathan Bossart wrote:

>-# all versions of pg_crc32c_armv8.o need CFLAGS_CRC
>-pg_crc32c_armv8.o: CFLAGS+=$(CFLAGS_CRC)
>-pg_crc32c_armv8_shlib.o: CFLAGS+=$(CFLAGS_CRC)
>-pg_crc32c_armv8_srv.o: CFLAGS+=$(CFLAGS_CRC)
>
>Why are these lines deleted?
>
>-  ['pg_crc32c_armv8', 'USE_ARMV8_CRC32C_WITH_RUNTIME_CHECK', 'crc'],
>+  ['pg_crc32c_armv8', 'USE_ARMV8_CRC32C_WITH_RUNTIME_CHECK'],
>
>What is the purpose of this change?

Because I added `__attribute__((target("+crc+crypto")))` before the functions that require crc extension and crypto
extension,so they are removed here. 

>+__attribute__((target("+crc+crypto")))
>
>I'm not sure we can assume that all compilers will understand this, and I'm
>not sure we need it.

CFLAGS_CRC is "-march=armv8-a+crc". Generally, if -march is supported, __attribute__ is also supported.
In addition, I am not sure about the source file pg_crc32c_armv8.c, if CFLAGS_CRC and CFLAGS_CRYPTO are needed at the
sametime, how should it be expressed in the makefile? 



IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you
arenot the intended recipient, please notify the sender immediately and do not disclose the contents to any other
person,use it for any purpose, or store or copy the information in any medium. Thank you. 

Attachment

pgsql-hackers by date:

Previous
From: "Fujii.Yuki@df.MitsubishiElectric.co.jp"
Date:
Subject: RE: Partial aggregates pushdown
Next
From: Давыдов Виталий
Date:
Subject: Re: How to accurately determine when a relation should use local buffers?