On Thu, Aug 16, 2007 at 03:30:44AM +0200, Segher Boessenkool wrote:

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Part of the motivation here is to fix heisenbugs.  If I knew where 
they

By the same token we should probably disable optimisations
altogether since that too can create heisenbugs.

Precisely the point -- use of volatile (whether in casts or on asms)
in these cases are intended to disable those optimizations likely to
result in heisenbugs.

The only thing volatile on an asm does is create a side effect
on the asm statement; in effect, it tells the compiler "do not
remove this asm even if you don't need any of its outputs".

It's not disabling optimisation likely to result in bugs,
heisen- or otherwise; _not_ putting the volatile on an asm
that needs it simply _is_ a bug :-)

Yep.  And the reason it is a bug is that it fails to disable
the relevant compiler optimizations.  So I suspect that we might
actually be saying the same thing here.

						Thanx, Paul