[X86-64] Support Intel AMX instructions
INTEL ADVANCED MATRIX EXTENSIONS (AMX).
AMX is a new programming paradigm, it has a set of 2-dimensional registers
(TILES) representing sub-arrays from a larger 2-dimensional memory image and
operate on TILES.
Spec can be found in Chapter 3 here https://software.intel.com/content/www/us/en/develop/download/intel-architecture-instruction-set-extensions-programming-reference.html
Reviewers: LuoYuanke, annita.zhang, pengfei, RKSimon, xiangzhangllvm
Reviewed By: xiangzhangllvm
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D82705