From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
cc: Andrew Gierth <andrew@tao11.riddles.org.uk>,
        David Rowley <david.rowley@2ndquadrant.com>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
        Thomas Munro <thomas.munro@enterprisedb.com>
Subject: Re: Using POPCNT and other advanced bit manipulation instructions
In-reply-to: <27185.1550097476@sss.pgh.pa.us>
References: <20190213221719.GA15976@alvherre.pgsql>
 <26998.1550097202@sss.pgh.pa.us> <27185.1550097476@sss.pgh.pa.us>
Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Wed, 13 Feb 2019 17:37:56 -0500"
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Date: Wed, 13 Feb 2019 22:38:04 -0500
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And, while I'm complaining: why the devil is use of the compiler builtins
gated by HAVE__GET_CPUID?  This is unbelievably Intel-centric, because
it prevents use of the builtins on other architectures.  If the builtin
exists, we should use it, full stop.  There's no reason to expect that it
would be slower than hand-rolled code, regardless of the architecture.

I'd be inclined to rip out all of the run-time-detection logic here;
I doubt any of it is buying anything that's worth the price of an
indirect call.

			regards, tom lane