Resolve static analyser report on pointer dereferencing after null ch…

…eck (llvm#88278)

- Resolve Static Analyzer Check Failure: Pointer Dereferencing After
Null Check.
- Minor naming and style improvement

Change-Id: I970ef318ffbde90c779c3e9b1336f3cd76cd5c4d

llvm/lib/Target/AMDGPU/AMDGPULowerModuleLDSPass.cpp

@@ -1034,43 +1034,40 @@ class AMDGPULowerModuleLDS {
  void removeNoLdsKernelIdFromReachable(CallGraph &CG, Function *KernelRoot) {
  KernelRoot->removeFnAttr("amdgpu-no-lds-kernel-id");
 
- SmallVector<Function *> Tmp({CG[KernelRoot]->getFunction()});
- if (!Tmp.back())
- return;
-
+ SmallVector<Function *> WorkList({CG[KernelRoot]->getFunction()});
  SmallPtrSet<Function *, 8> Visited;
  bool SeenUnknownCall = false;
 
- do {
- Function *F = Tmp.pop_back_val();
+ while (!WorkList.empty()) {
+ Function *F = WorkList.pop_back_val();
 
- for (auto &N : *CG[F]) {
- if (!N.second)
+ for (auto &CallRecord : *CG[F]) {
+ if (!CallRecord.second)
  continue;
 
- Function *Callee = N.second->getFunction();
+ Function *Callee = CallRecord.second->getFunction();
  if (!Callee) {
  if (!SeenUnknownCall) {
  SeenUnknownCall = true;
 
  // If we see any indirect calls, assume nothing about potential
  // targets.
  // TODO: This could be refined to possible LDS global users.
- for (auto &N : *CG.getExternalCallingNode()) {
- Function *PotentialCallee = N.second->getFunction();
+ for (auto &ExternalCallRecord : *CG.getExternalCallingNode()) {
+ Function *PotentialCallee =
+ ExternalCallRecord.second->getFunction();
+ assert(PotentialCallee);
  if (!isKernelLDS(PotentialCallee))
  PotentialCallee->removeFnAttr("amdgpu-no-lds-kernel-id");
  }
-
- continue;
  }
+ } else {
+ Callee->removeFnAttr("amdgpu-no-lds-kernel-id");
+ if (Visited.insert(Callee).second)
+ WorkList.push_back(Callee);
  }
-
- Callee->removeFnAttr("amdgpu-no-lds-kernel-id");
- if (Visited.insert(Callee).second)
- Tmp.push_back(Callee);
  }
- } while (!Tmp.empty());
+ }
  }
 
  DenseMap<Function *, GlobalVariable *> lowerDynamicLDSVariables(