AMDGPU/GlobalISel: Try generated matcher before add/sub code
AMDGPU/GlobalISel: Try generated matcher before add/sub code

This will allow optimization patterns which fold adds away to work.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@371406 91177308-0d34-0410-b5e6-96231b3b80d8

GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm