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Re: Call for compiler help/advice: atomic builtins for v3
- From: Richard Henderson <rth at redhat dot com>
- To: Paolo Carlini <pcarlini at suse dot de>
- Cc: gcc at gcc dot gnu dot org, libstdc++ at gcc dot gnu dot org, Ian Lance Taylor <ian at airs dot com>
- Date: Sun, 6 Nov 2005 10:51:51 -0800
- Subject: Re: Call for compiler help/advice: atomic builtins for v3
- References: <436DDC36.8070308@suse.de>
On Sun, Nov 06, 2005 at 11:34:30AM +0100, Paolo Carlini wrote:
> Thus my request: would it be possible to have available the builtins
> unconditionally, by way of a slow (locks) fallback replacing the real
> implementation when the actual target code doesn't allow for them?
I suppose that in some cases it would be possible to implement
them in libgcc. Certainly we provided for that possibility
by expanding to external calls.
Not all targets are going to be able to implement the builtins,
even with locks. It is imperitive that the target have an
atomic store operation, so that other read-only references to
the variable see either the old or new value, but not a mix.
r~