[AMDGPU] Wave and register controls

- Implemented amdgpu-flat-work-group-size attribute
- Implemented amdgpu-num-active-waves-per-eu attribute
- Implemented amdgpu-num-sgpr attribute
- Implemented amdgpu-num-vgpr attribute
- Dynamic LDS constraints are in a separate patch

Patch by Tom Stellard and Konstantin Zhuravlyov

Differential Revision: https://reviews.llvm.org/D21562



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280747 91177308-0d34-0410-b5e6-96231b3b80d8
32 files changed