[Pixman] clang 3.0: Unsupported asm: input constraint with a matching output constraint of incompatible type!

[Ryan Schmidt]

On May 30, 2012, at 20:33, Søren Sandmann wrote:

> Maybe the difference is that you are using "-O0" where Ryan is using
> "-O2". The "K" constraint requires the argument to be compile-time
> constant, which it is, but clang may not be able to see that without
> optimization.

Confirmed: If I set configure.optflags=-O0 on the command line, the configure check whether to use MMX intrinsics correctly says "no" and pixman builds. But with -O1 or the default -O2 it says "yes" and the build subsequently fails.

Will using -O0 be detrimental to performance, or is that a viable workaround we could put into the MacPorts portfile?

Someone else in our ticket commented that we could use the --disable-mmx configure arg. Would that be better or worse?