AMDGPU: Refactor Subtarget classes

Summary:
This is a follow-up to r335942.
- Merge SISubtarget into AMDGPUSubtarget and rename to GCNSubtarget
- Rename AMDGPUCommonSubtarget to AMDGPUSubtarget
- Merge R600Subtarget::Generation and GCNSubtarget::Generation into
  AMDGPUSubtarget::Generation.

Reviewers: arsenm, jvesely

Subscribers: kzhuravl, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D49037

llvm-svn: 336851
diff --git a/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp b/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp
index 1b054b9..f09b7f6 100644
--- a/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp
+++ b/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp
@@ -35,7 +35,7 @@
 
   MF = &DAG->MF;
 
-  const SISubtarget &ST = MF->getSubtarget<SISubtarget>();
+  const GCNSubtarget &ST = MF->getSubtarget<GCNSubtarget>();
 
   // FIXME: This is also necessary, because some passes that run after
   // scheduling and before regalloc increase register pressure.
@@ -294,7 +294,7 @@
 GCNScheduleDAGMILive::GCNScheduleDAGMILive(MachineSchedContext *C,
                         std::unique_ptr<MachineSchedStrategy> S) :
   ScheduleDAGMILive(C, std::move(S)),
-  ST(MF.getSubtarget<SISubtarget>()),
+  ST(MF.getSubtarget<GCNSubtarget>()),
   MFI(*MF.getInfo<SIMachineFunctionInfo>()),
   StartingOccupancy(MFI.getOccupancy()),
   MinOccupancy(StartingOccupancy), Stage(0), RegionIdx(0) {