[PATCH][X86] Add target specific combine rules to fold SSE/AVX/AVX2 blend intrinsics.

[Philip Reames]

On 05/15/2014 01:45 PM, Alex Rosenberg wrote:
> After r208664, most of those patch is dead code since Clang no longer generates these intrinsics except the blendv variants. We have to keep the intrinsics as is until the next release because they may exist in IR, but we should remove unused ones when possible.
I want to express disagreement with the assumption here.  Using Clang as 
our *only* benchmark for when an intrinsic is worth retaining is wrong.  
There are a number of other frontends which use LLVM and we should not 
remove something just because *one* no longer uses something.  Also, 
aren't most of these usable in code compiled via Clang?

Just to be clear, this comment is getting at general philosophy, not 
this specific case.  I have no actual opinion w.r.t. the case at hand.

Philip