From: Tom Lane <tgl@sss.pgh.pa.us>
To: John Naylor <johncnaylorls@gmail.com>
cc: Andres Freund <andres@anarazel.de>, pgsql-committers@lists.postgresql.org,
        cookt@blackduck.com
Subject: Re: pgsql: Inline CRC computation for small fixed-length input on x86
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Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Mon, 31 Mar 2025 09:09:06 -0400"
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Date: Mon, 31 Mar 2025 09:33:48 -0400
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I wrote:
>> What I conclude is that Red Hat hot-wired gcc to assume -msse4.2,
>> but they didn't hot-wire clang the same way.

> In confirmation of that: everything goes through fine if I manually
> add -msse4.2 to configure's choice of BITCODE_CFLAGS.

Also, possibly useful for testing purposes: I can reproduce the
build failure on RHEL8, and probably elsewhere, with

./configure CFLAGS="-O2 -msse4.2" --with-llvm

In this form it's clearly pilot error, because I didn't do anything
to put -msse4.2 into CXXFLAGS.  But this is another way of confirming
that the underlying problem is different default -m switches between
gcc and clang.  I'm kind of surprised we have not gotten bitten by
that before.

			regards, tom lane