GCC memory barriers are missing "cc" clobbers

From: Andres Freund <andres(at)2ndquadrant(dot)com>
To: pgsql-hackers(at)postgresql(dot)org
Subject: GCC memory barriers are missing "cc" clobbers
Date: 2014-09-19 10:00:16
Message-ID: 20140919100016.GH4277@alap3.anarazel.de
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Hi,

barrier.h defines memory barriers for x86 as:
32bit:
#define pg_memory_barrier() \
__asm__ __volatile__ ("lock; addl $0,0(%%esp)" : : : "memory")
64bit:
#define pg_memory_barrier() \
__asm__ __volatile__ ("lock; addl $0,0(%%rsp)" : : : "memory")

But addl sets condition flags. So this really also needs a "cc" clobber?
Or am I missing something?

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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