Address first round of review comments.

- convert assert to early return.
- change dyn_cast<> following an isa<> to a cast<>
- remove a null check after a cast<>

Author: mandlebug

llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp

@@ -477,9 +477,10 @@ static void collectTOCStats(PPCAsmPrinter::TOCEntryType Type) {
 static CodeModel::Model getCodeModel(const PPCSubtarget &S,
                                      const TargetMachine &TM,
                                      const MachineOperand &MO) {
-  assert(S.isAIXABI() && "ELF per global code model not supported yet");
-
   CodeModel::Model ModuleModel = TM.getCodeModel();
+  // Per global code model is only support on AIX.
+  if (!S.isAIXABI())
+    return ModuleModel;
 
   // If the operand is not a global address then there is no
   // global variable to carry an attribute.
@@ -493,7 +494,7 @@ static CodeModel::Model getCodeModel(const PPCSubtarget &S,
     return ModuleModel;
 
   std::optional<CodeModel::Model> MaybeCodeModel =
-      dyn_cast<GlobalVariable>(GV)->getCodeModel();
+      cast<GlobalVariable>(GV)->getCodeModel();
   if (MaybeCodeModel)
     return *MaybeCodeModel;
 

llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp

@@ -575,11 +575,7 @@ static CodeModel::Model getCodeModel(const PPCSubtarget &Subtarget,
   if (!isa<GlobalAddressSDNode>(Operand))
     return ModuleModel;
 
-  GlobalAddressSDNode *GA = cast<GlobalAddressSDNode>(Operand);
-  if (!GA)
-    return ModuleModel;
-
-  const GlobalValue *GV = GA->getGlobal();
+  const GlobalValue *GV = cast<GlobalAddressSDNode>(Operand)->getGlobal();
   if (!GV || !isa<GlobalVariable>(GV))
     return ModuleModel;