[LLVMdev] Need Advice on AVX

David Greene dag at cray.com
Tue Dec 1 08:11:19 PST 2009

On Thursday 26 November 2009 14:25, Chris Lattner wrote:

> > Modeling subregisters isn't hard.  Do you have some guidance as to when
> > one method is preferable?  I am leaning toward using the modifier since
> > conceptually, a vector_extract of element zero on a v4i64 makes sense
> > with AVX (so it is "legal").  You just have to emit the register name as
> > "xmm" rather than "ymm."  Why write an additional complicated pattern for
> > this case?
> Please don't use asmprinter modifiers.  I'm trying to remove them as part
> of the MCization code.  Please use the SUBREG machine instr and (subreg)
> tblgen node as appropriate.



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