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Re: __sync_swap* with acq/rel/full memory barrier semantics

From: Aldy Hernandez <aldyh at redhat dot com>
To: Andrew MacLeod <amacleod at redhat dot com>
Cc: Richard Henderson <rth at redhat dot com>, Jakub Jelinek <jakub at redhat dot com>, "Joseph S. Myers" <joseph at codesourcery dot com>, gcc-patches <gcc-patches at gcc dot gnu dot org>
Date: Fri, 08 Jul 2011 11:30:47 -0500
Subject: Re: __sync_swap* with acq/rel/full memory barrier semantics
References: <4DDAE516.4010307@redhat.com> <Pine.LNX.4.64.1105232300520.28552@digraph.polyomino.org.uk> <4DE3F8ED.6020109@redhat.com> <4DE7E0A6.9070400@redhat.com> <20110602192514.GA17079@tyan-ft48-01.lab.bos.redhat.com> <4DE7EA11.30306@redhat.com> <4DE8EF17.5020400@redhat.com> <4DFBC33E.60408@redhat.com> <4DFCFCE2.1090307@redhat.com> <4DFF73C1.6080609@redhat.com>

Some names include "sync" and some don't?


Well, I was going to blame Aldy :-) but then I went to look at this, and
thats the same way *all* the other __sync instructions seem to be.

ie:

builtins.c:expand_builtin_lock_test_and_set (enum machine_mode mode,
tree exp,
builtins.c: case BUILT_IN_LOCK_TEST_AND_SET_1:
builtins.c: case BUILT_IN_LOCK_TEST_AND_SET_2:
builtins.c: case BUILT_IN_LOCK_TEST_AND_SET_4:

whereas everything else is 'sync_lock_test_and_set'..

So i guess it falls to prior art... I assume Aldy just cut-and-pasted
for his new routine and just changed the names in the same format.

Correct, this was the way all the other sync builtins were implemented. I found it odd as well, but wanted to keep my changes to a minimum.

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