AMDGPU: Replace subtarget check with an assert

[arsenm]

Summary

This is already checked by the pattern subtarget predicate.

[rampitec]

LGTM

[arsenm]

f7521dc292221e502d013e9505598df461659362

llvm/lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp

bool AMDGPUDAGToDAGISel::SelectSMRDImm(SDValue Addr, SDValue &SBase,
                                        SDValue &Offset) const {
   bool Imm;
   return SelectSMRD(Addr, SBase, Offset, Imm) && Imm;
 }
 
 bool AMDGPUDAGToDAGISel::SelectSMRDImm32(SDValue Addr, SDValue &SBase,
                                          SDValue &Offset) const {
 
-  if (Subtarget->getGeneration() != AMDGPUSubtarget::SEA_ISLANDS)
-    return false;
+  assert(Subtarget->getGeneration() == AMDGPUSubtarget::SEA_ISLANDS);
 
   bool Imm;
   if (!SelectSMRD(Addr, SBase, Offset, Imm))
     return false;
 
   return !Imm && isa<ConstantSDNode>(Offset);
 }
 
 bool AMDGPUDAGToDAGISel::SelectSMRDSgpr(SDValue Addr, SDValue &SBase,
                                         SDValue &Offset) const {
   bool Imm;
   return SelectSMRD(Addr, SBase, Offset, Imm) && !Imm &&
          !isa<ConstantSDNode>(Offset);
 }
 
 bool AMDGPUDAGToDAGISel::SelectSMRDBufferImm(SDValue Addr,
                                              SDValue &Offset) const {
   bool Imm;
   return SelectSMRDOffset(Addr, Offset, Imm) && Imm;
 }
 
 bool AMDGPUDAGToDAGISel::SelectSMRDBufferImm32(SDValue Addr,
                                                SDValue &Offset) const {
-  if (Subtarget->getGeneration() != AMDGPUSubtarget::SEA_ISLANDS)
-    return false;
+  assert(Subtarget->getGeneration() == AMDGPUSubtarget::SEA_ISLANDS);
 
   bool Imm;
   if (!SelectSMRDOffset(Addr, Offset, Imm))
     return false;
 
   return !Imm && isa<ConstantSDNode>(Offset);
 }