AVX-512: added cost for some AVX-512 instructions


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217863 91177308-0d34-0410-b5e6-96231b3b80d8
[InstCombine] Remove redundant test case.

Patch by Sonam Kumari!

Differential Revision: http://reviews.llvm.org/D5284

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217865 91177308-0d34-0410-b5e6-96231b3b80d8