Re: inline asm semantics: output constraint width smaller than input

[H. Peter Anvin]

Ingo Molnar wrote:
> > Hi,
> >
> > I am trying to build the kernel with LLVM 2.5 prerelease (using 
> > llvm-gcc-4.2 frontend), however I am running into some inline asm 
> > semantics issues, and after some discussion on LLVM bugzilla I would 
> > like to know if you would be accepting patches for this: 
> > http://llvm.org/bugs/show_bug.cgi?id=3373
> >
> > The problem is when "a" output constraint is used with a variable of 
> > smaller width than the "0" input constraint.

IMO, that's an LLVM bug and should be fixed in LLVM while it is in 
prerelease.  That particular constraint is a serious one, and will haunt 
us for many years if we allow ourselves to go down the path of having to 
fix that every time it crops up.

	-hpa
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