[dataflow] Log flow condition to the correct stream.

clang/include/clang/Analysis/FlowSensitive/DataflowAnalysisContext.h

public:
   /// identified by `Token` are always true.
   bool flowConditionIsTautology(AtomicBoolValue &Token);
 
   /// Returns true if `Val1` is equivalent to `Val2`.
   /// Note: This function doesn't take into account constraints on `Val1` and
   /// `Val2` imposed by the flow condition.
   bool equivalentBoolValues(BoolValue &Val1, BoolValue &Val2);
 
-  LLVM_DUMP_METHOD void dumpFlowCondition(AtomicBoolValue &Token);
+  LLVM_DUMP_METHOD void dumpFlowCondition(AtomicBoolValue &Token,
+                                          llvm::raw_ostream &OS = llvm::dbgs());
 
   /// Returns the `ControlFlowContext` registered for `F`, if any. Otherwise,
   /// returns null.
   const ControlFlowContext *getControlFlowContext(const FunctionDecl *F);
 
   const Options &getOptions() { return Opts; }
 
 private:

clang/lib/Analysis/FlowSensitive/DataflowAnalysisContext.cpp

for (AtomicBoolValue *DepToken : DepsIt->second) {
       auto &NewDep = buildAndSubstituteFlowConditionWithCache(
           *DepToken, SubstitutionsCache);
       SubstitutionsCache[DepToken] = &NewDep;
     }
   }
   return substituteBoolValue(*ConstraintsIt->second, SubstitutionsCache);
 }
 
-void DataflowAnalysisContext::dumpFlowCondition(AtomicBoolValue &Token) {
+void DataflowAnalysisContext::dumpFlowCondition(AtomicBoolValue &Token,
+                                                llvm::raw_ostream &OS) {
   llvm::DenseSet<BoolValue *> Constraints = {&Token};
   llvm::DenseSet<AtomicBoolValue *> VisitedTokens;
   addTransitiveFlowConditionConstraints(Token, Constraints, VisitedTokens);
 
   llvm::DenseMap<const AtomicBoolValue *, std::string> AtomNames = {
       {&getBoolLiteralValue(false), "False"},
       {&getBoolLiteralValue(true), "True"}};
-  llvm::dbgs() << debugString(Constraints, AtomNames);
+  OS << debugString(Constraints, AtomNames);
 }
 
 const ControlFlowContext *
 DataflowAnalysisContext::getControlFlowContext(const FunctionDecl *F) {
   // Canonicalize the key:
   F = F->getDefinition();
   if (F == nullptr)
     return nullptr;

clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp

for (auto [E, L] : ExprToLoc)
     OS << "  [" << E << ", " << L << "]\n";
 
   OS << "LocToVal:\n";
   for (auto [L, V] : LocToVal) {
     OS << "  [" << L << ", " << V << ": " << *V << "]\n";
   }
 
   OS << "FlowConditionToken:\n";
-  DACtx->dumpFlowCondition(*FlowConditionToken);
+  DACtx->dumpFlowCondition(*FlowConditionToken, OS);
 }
 
 void Environment::dump() const {
   dump(llvm::dbgs());
 }
 
 } // namespace dataflow
 } // namespace clang