[AVX-512] Teach fastisel load/store handling to use EVEX encoded instructions for 128/256-bit vectors and scalar single/double.

Still need to fix the register classes to allow the extended range of registers.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280682 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed