Re: gcc 4.1 implements compiler builtins for atomic ops

[Ulrich Drepper <drepper at redhat dot com>]

Benjamin Herrenschmidt wrote:
> Yes, but that encourage developers to use them direcltly, which means
> that they'll, for example, produce code that will either be broken for
> 405 or will have a spurrious sync on non-405 which is a significant
> performance issue.

So what?  This is an issue for binaries.  How many binaries are shared
between reasonable implementations and the broken ones?  Don't generate
the sync op by default and tell the losers who use the broken processors
to throw them out or build their own binaries.  You can even invent a
mechanism to check for binaries compiled this way.

And go, beat up the processor people.  They cause the problems.  We
cannot have everybody else suffer from that.  We have the APIs for all
kinds of processors and every arch which needs to be treated special
will fall aside since the extra handling is not acceptable to most
programmers.

-- 
â Ulrich Drepper â Red Hat, Inc. â 444 Castro St â Mountain View, CA â

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