[x86][AVX512] Lowering kunpack intrinsics to LLVM IR

This patch, together with a matching clang patch (https://reviews.llvm.org/D39719), implements the lowering of X86 kunpack intrinsics to IR.

Differential Revision: https://reviews.llvm.org/D39720

Change-Id: I4088d9428478f9457f6afddc90bd3d66b3daf0a1

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@319778 91177308-0d34-0410-b5e6-96231b3b80d8
10 files changed