Split AMDGPUSubtarget into amdgcn/r600 specific subclasses.
This removes most of the static_casting of the basic codegen
classes everywhere, and tries to restrict the features
visible on the wrong target.
llvm-svn: 273652
- Insert one nop for each high level statement instead of two
- Do not insert nop before prologue
Differential Revision: http://reviews.llvm.org/D20215
llvm-svn: 269452