[llvm-commits] [llvm] r92939 - /llvm/trunk/include/llvm/IntrinsicsX86.td

[David Greene]

On Thursday 07 January 2010 14:45, Eric Christopher wrote:
> On Jan 7, 2010, at 12:22 PM, David Greene wrote:
> > What llvm intrinsics?
> >
> > We don't "need" them in the sense of functionality, but gcc defines them
> > so it makes sense to support them.
> >
> > Adding them also makes the SIMD reorganization a bit simpler.
>
> I don't think you're understanding what Evan was saying.  We don't need, at
> least, the "gcc intrinsic" part of it because the gcc intrinsic should be
> lowered to explicit llvm instructions instead of llvm intrinsics.

Yes, I misread "instruction" as "intrinsic."

> The gcc intrinsics should be supported, but if possible they should be
> lowered to instructions instead of intrinsics.

The non-orthogonality of having the "ss" intrinsics but not the "ps"
intrinsics (and sd/pd) means that we would need to special-case these
operations in the .td files rather than generating one pattern for all
variants (ss/sd/ps/pd intrinsics and those matched from llvm instructions).
This makes specifying SIMD instructions unnecessarily verbose.

Why do we have the scalar intrinsics anyway?  Those operations can match to 
llvm instructions as well, can't they?

If we get rid of the scalar intrinsics, I have no problem dumping the vector
ones.  I just want consistency.

                                -Dave