[clang][dataflow] Store DeclContext of block being analysed in Environment if available.

Differential Revision: https://reviews.llvm.org/D131065

Author: weiyi-t

clang/include/clang/Analysis/FlowSensitive/DataflowEnvironment.h

@@ -347,6 +347,13 @@ class Environment {
   /// imply that `Val` is true.
   bool flowConditionImplies(BoolValue &Val) const;
 
+  /// Returns the `DeclContext` of the block being analysed, if any. Otherwise,
+  /// returns null.
+  const DeclContext *getDeclCtx() { return DeclCtx; }
+
+  /// Sets the `DeclContext` of the block being analysed.
+  void setDeclCtx(const DeclContext *Ctx) { DeclCtx = Ctx; }
+
   /// Returns the `ControlFlowContext` registered for `F`, if any. Otherwise,
   /// returns null.
   const ControlFlowContext *getControlFlowContext(const FunctionDecl *F) {
@@ -377,6 +384,9 @@ class Environment {
   // `DACtx` is not null and not owned by this object.
   DataflowAnalysisContext *DACtx;
 
+  // `DeclContext` of the block being analysed if provided.
+  const DeclContext *DeclCtx;
+
   // In a properly initialized `Environment`, `ReturnLoc` should only be null if
   // its `DeclContext` could not be cast to a `FunctionDecl`.
   StorageLocation *ReturnLoc = nullptr;

clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp

@@ -154,7 +154,7 @@ Environment::Environment(DataflowAnalysisContext &DACtx)
     : DACtx(&DACtx), FlowConditionToken(&DACtx.makeFlowConditionToken()) {}
 
 Environment::Environment(const Environment &Other)
-    : DACtx(Other.DACtx), ReturnLoc(Other.ReturnLoc),
+    : DACtx(Other.DACtx), DeclCtx(Other.DeclCtx), ReturnLoc(Other.ReturnLoc),
       ThisPointeeLoc(Other.ThisPointeeLoc), DeclToLoc(Other.DeclToLoc),
       ExprToLoc(Other.ExprToLoc), LocToVal(Other.LocToVal),
       MemberLocToStruct(Other.MemberLocToStruct),
@@ -168,9 +168,11 @@ Environment &Environment::operator=(const Environment &Other) {
 }
 
 Environment::Environment(DataflowAnalysisContext &DACtx,
-                         const DeclContext &DeclCtx)
+                         const DeclContext &DeclCtxArg)
     : Environment(DACtx) {
-  if (const auto *FuncDecl = dyn_cast<FunctionDecl>(&DeclCtx)) {
+  setDeclCtx(&DeclCtxArg);
+
+  if (const auto *FuncDecl = dyn_cast<FunctionDecl>(DeclCtx)) {
     assert(FuncDecl->getBody() != nullptr);
     initGlobalVars(*FuncDecl->getBody(), *this);
     for (const auto *ParamDecl : FuncDecl->parameters()) {
@@ -185,7 +187,7 @@ Environment::Environment(DataflowAnalysisContext &DACtx,
     ReturnLoc = &createStorageLocation(ReturnType);
   }
 
-  if (const auto *MethodDecl = dyn_cast<CXXMethodDecl>(&DeclCtx)) {
+  if (const auto *MethodDecl = dyn_cast<CXXMethodDecl>(DeclCtx)) {
     auto *Parent = MethodDecl->getParent();
     assert(Parent != nullptr);
     if (Parent->isLambda())
@@ -210,6 +212,9 @@ Environment Environment::pushCall(const CallExpr *Call) const {
 
   const auto *FuncDecl = Call->getDirectCallee();
   assert(FuncDecl != nullptr);
+
+  Env.setDeclCtx(FuncDecl);
+
   // FIXME: In order to allow the callee to reference globals, we probably need
   // to call `initGlobalVars` here in some way.
 
@@ -252,12 +257,12 @@ Environment Environment::pushCall(const CallExpr *Call) const {
 
 void Environment::popCall(const Environment &CalleeEnv) {
   // We ignore `DACtx` because it's already the same in both. We don't want the
-  // callee's `ReturnLoc` or `ThisPointeeLoc`. We don't bring back `DeclToLoc`
-  // and `ExprToLoc` because we want to be able to later analyze the same callee
-  // in a different context, and `setStorageLocation` requires there to not
-  // already be a storage location assigned. Conceptually, these maps capture
-  // information from the local scope, so when popping that scope, we do not
-  // propagate the maps.
+  // callee's `DeclCtx`, `ReturnLoc` or `ThisPointeeLoc`. We don't bring back
+  // `DeclToLoc` and `ExprToLoc` because we want to be able to later analyze the
+  // same callee in a different context, and `setStorageLocation` requires there
+  // to not already be a storage location assigned. Conceptually, these maps
+  // capture information from the local scope, so when popping that scope, we do
+  // not propagate the maps.
   this->LocToVal = std::move(CalleeEnv.LocToVal);
   this->MemberLocToStruct = std::move(CalleeEnv.MemberLocToStruct);
   this->FlowConditionToken = std::move(CalleeEnv.FlowConditionToken);
@@ -304,11 +309,13 @@ LatticeJoinEffect Environment::join(const Environment &Other,
   assert(DACtx == Other.DACtx);
   assert(ReturnLoc == Other.ReturnLoc);
   assert(ThisPointeeLoc == Other.ThisPointeeLoc);
+  assert(DeclCtx == Other.DeclCtx);
 
   auto Effect = LatticeJoinEffect::Unchanged;
 
   Environment JoinedEnv(*DACtx);
 
+  JoinedEnv.setDeclCtx(DeclCtx);
   JoinedEnv.ReturnLoc = ReturnLoc;
   JoinedEnv.ThisPointeeLoc = ThisPointeeLoc;