[NVPTX] Avoid repeated map lookups (NFC) (#111627)

Author: kazutakahirata

llvm/lib/Target/NVPTX/NVPTXAsmPrinter.cpp

@@ -1145,13 +1145,7 @@ void NVPTXAsmPrinter::printModuleLevelGV(const GlobalVariable *GVar,
   const Function *demotedFunc = nullptr;
   if (!processDemoted && canDemoteGlobalVar(GVar, demotedFunc)) {
     O << "// " << GVar->getName() << " has been demoted\n";
-    if (localDecls.find(demotedFunc) != localDecls.end())
-      localDecls[demotedFunc].push_back(GVar);
-    else {
-      std::vector<const GlobalVariable *> temp;
-      temp.push_back(GVar);
-      localDecls[demotedFunc] = temp;
-    }
+    localDecls[demotedFunc].push_back(GVar);
     return;
   }
 
@@ -1368,10 +1362,11 @@ void NVPTXAsmPrinter::AggBuffer::printWords(raw_ostream &os) {
 }
 
 void NVPTXAsmPrinter::emitDemotedVars(const Function *f, raw_ostream &O) {
-  if (localDecls.find(f) == localDecls.end())
+  auto It = localDecls.find(f);
+  if (It == localDecls.end())
     return;
 
-  std::vector<const GlobalVariable *> &gvars = localDecls[f];
+  std::vector<const GlobalVariable *> &gvars = It->second;
 
   const NVPTXTargetMachine &NTM = static_cast<const NVPTXTargetMachine &>(TM);
   const NVPTXSubtarget &STI =