[PATCH] D59883: Lower generic MASSV entries to PowerPC subtarget-specific entries

Wed Aug 28 11:03:37 PDT 2019

pjeeva01 added a comment.

In D59883#1649479 <https://reviews.llvm.org/D59883#1649479>, @jsji wrote:

> > A separate pass for MASSV lowering is worthwhile because it allows better separation of concerns. 
> >  In the future, if need be, other PPC sub-target specific lowering decisions for MASSV may be encapsulated in this pass too.
>
> What is the benefits other than `allows better separation of concerns`?
>  I don't see this compelling reason to be a pass, especially considering the unnecessary compile time it will cost.

1. *_massv functions serve as place holder for math functions during loop vectorization. They are not actual entries in the MASS library. I think lowering them to actual entries in the MASS library deserves  a separate pass rather than polluting the TargetLowering.cpp, which is already big as it is.

2. If we were to use setLibcallName, we would need to repeat the list of all supported MASS entries in TargetLowering as well. With the current structure, we are reusing the list in VecFuncs.def. Also, this structure sits well with vectorization of math functions with other libraries too, namely: SVML and Accelerate.

Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D59883/new/

https://reviews.llvm.org/D59883