[PATCH] D20897: [AVX512/AVX][Intrinsics] Fix Variable Bit Shift Right Arithmetic intrinsic lowering.

[Simon Pilgrim via llvm-commits]

RKSimon added a comment.

In http://reviews.llvm.org/D20897#453183, @igorb wrote:

> I think we need this patch for correctness in case we got this intrinsic with const index in back-end ( for example if  InstCombiner doesn't run , -O0 compilation) .


Except this isn't a correctness issue, its an optimization no? The code will run fine at -O0 or higher as it will lower to the vpsrav intrinsic which supports the out-of-range shift value and will give the correct result.

If this was in combineINTRINSIC_WO_CHAIN (which we recently removed as it wasn't being used....) I think we could accept this but only if we have a use case that InstCombine isn't catching.


Repository:
  rL LLVM

http://reviews.llvm.org/D20897