[NVPTX] Fixed param symbol name lowering in unnamed funcs. Fixes PR40817

[jascha]

Summary

NVPTXTargetLowering::getParamSymbol used MachineFunction::getName
instead of the mangled symbol name. For unnamed functions (e.g. like
IPO/MergeFunction may create them) this produced an operand name that is
inconsistent with other parts of this module that emit parameter names.

[tra]

Could you add a test to demonstrate the issue and verify that it is fixed?

[jascha]

Patch has been added sometime before c8238de61fc2a.

lib/Target/NVPTX/NVPTXISelLowering.cpp

SDValue NVPTXTargetLowering::LowerSTOREi1(SDValue Op, SelectionDAG &DAG) const {
   return Result;
 }
 
 SDValue
 NVPTXTargetLowering::getParamSymbol(SelectionDAG &DAG, int idx, EVT v) const {
   std::string ParamSym;
   raw_string_ostream ParamStr(ParamSym);
 
-  ParamStr << DAG.getMachineFunction().getName() << "_param_" << idx;
+  auto& TM = getTargetMachine();
+  auto F = &DAG.getMachineFunction().getFunction();
+  TM.getSymbol(F)->print(ParamStr, TM.getMCAsmInfo());
+  ParamStr << "_param_" << idx;
   ParamStr.flush();
 
   std::string *SavedStr =
     nvTM->getManagedStrPool()->getManagedString(ParamSym.c_str());
   return DAG.getTargetExternalSymbol(SavedStr->c_str(), v);
 }
 
 // Check to see if the kernel argument is image*_t or sampler_t