[analyzer] Introduce a convenience method for getting a CallEvent from an arbitrary Stmt

[NoQ]

clang/include/clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h

1141–1148

We should explain that these two functions are radically different. Namely, in getCaller() the location context argument is the callee context (from which the call site can be derived), while in getCall() it is the caller context (from which the call site cannot be derived). We should probably reflect this in function names as well, because getCaller() is already a pretty uninformative name.

Still, it should be possible to re-use getCall() in getCaller().

[NoQ]

Thx! Yeah, i guess the calling convention is kinda reasonable as long as comments are in place.

clang/include/clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h

     static_assert(sizeof(T) == sizeof(CallEventTemplateTy),
                   "CallEvent subclasses are not all the same size");
     return new (allocate()) T(A1, A2, A3, A4, St, LCtx);
   }
 
 public:
   CallEventManager(llvm::BumpPtrAllocator &alloc) : Alloc(alloc) {}
 
+  /// Gets an outside caller given a callee context.
   CallEventRef<>
   getCaller(const StackFrameContext *CalleeCtx, ProgramStateRef State);
 
+  /// Gets a call event for a function call, Objective-C method call,
+  /// or a 'new' call.
+  CallEventRef<>
+  getCall(const Stmt *S, ProgramStateRef State,
+          const LocationContext *LC);
+
   CallEventRef<>
   getSimpleCall(const CallExpr *E, ProgramStateRef State,
                 const LocationContext *LCtx);
 
   CallEventRef<ObjCMethodCall>
   getObjCMethodCall(const ObjCMessageExpr *E, ProgramStateRef State,
                     const LocationContext *LCtx) {
     return create<ObjCMethodCall>(E, State, LCtx);

clang/lib/StaticAnalyzer/Core/CallEvent.cpp

                             ProgramStateRef State) {
   const LocationContext *ParentCtx = CalleeCtx->getParent();
   const LocationContext *CallerCtx = ParentCtx->getStackFrame();
   assert(CallerCtx && "This should not be used for top-level stack frames");
 
   const Stmt *CallSite = CalleeCtx->getCallSite();
 
   if (CallSite) {
-    if (const CallExpr *CE = dyn_cast<CallExpr>(CallSite))
-      return getSimpleCall(CE, State, CallerCtx);
-
-    switch (CallSite->getStmtClass()) {
-    case Stmt::CXXConstructExprClass:
-    case Stmt::CXXTemporaryObjectExprClass: {
-      SValBuilder &SVB = State->getStateManager().getSValBuilder();
-      const auto *Ctor = cast<CXXMethodDecl>(CalleeCtx->getDecl());
-      Loc ThisPtr = SVB.getCXXThis(Ctor, CalleeCtx);
-      SVal ThisVal = State->getSVal(ThisPtr);
-
-      return getCXXConstructorCall(cast<CXXConstructExpr>(CallSite),
-                                   ThisVal.getAsRegion(), State, CallerCtx);
-    }
-    case Stmt::CXXNewExprClass:
-      return getCXXAllocatorCall(cast<CXXNewExpr>(CallSite), State, CallerCtx);
-    case Stmt::ObjCMessageExprClass:
-      return getObjCMethodCall(cast<ObjCMessageExpr>(CallSite),
-                               State, CallerCtx);
-    default:
-      llvm_unreachable("This is not an inlineable statement.");
-    }
+    if (CallEventRef<> Out = getCall(CallSite, State, CallerCtx))
+      return Out;
+
+    Stmt::StmtClass SC = CallSite->getStmtClass();
+
+    // All other cases are handled by getCall.
+    assert(SC == Stmt::CXXConstructExprClass ||
+           SC == Stmt::CXXTemporaryObjectExprClass &&
+               "This is not an inlineable statement");
+
+    SValBuilder &SVB = State->getStateManager().getSValBuilder();
+    const auto *Ctor = cast<CXXMethodDecl>(CalleeCtx->getDecl());
+    Loc ThisPtr = SVB.getCXXThis(Ctor, CalleeCtx);
+    SVal ThisVal = State->getSVal(ThisPtr);
+
+    return getCXXConstructorCall(cast<CXXConstructExpr>(CallSite),
+                                 ThisVal.getAsRegion(), State, CallerCtx);
   }
 
   // Fall back to the CFG. The only thing we haven't handled yet is
   // destructors, though this could change in the future.
   const CFGBlock *B = CalleeCtx->getCallSiteBlock();
   CFGElement E = (*B)[CalleeCtx->getIndex()];
   assert((E.getAs<CFGImplicitDtor>() || E.getAs<CFGTemporaryDtor>()) &&
          "All other CFG elements should have exprs");

     Trigger = DeleteDtor->getDeleteExpr();
   else
     Trigger = Dtor->getBody();
 
   return getCXXDestructorCall(Dtor, Trigger, ThisVal.getAsRegion(),
                               E.getAs<CFGBaseDtor>().hasValue(), State,
                               CallerCtx);
 }
+
+CallEventRef<> CallEventManager::getCall(const Stmt *S, ProgramStateRef State,
+                                         const LocationContext *LC) {
+  if (const auto *CE = dyn_cast<CallExpr>(S)) {
+    return getSimpleCall(CE, State, LC);
+  } else if (const auto *NE = dyn_cast<CXXNewExpr>(S)) {
+    return getCXXAllocatorCall(NE, State, LC);
+  } else if (const auto *ME = dyn_cast<ObjCMessageExpr>(S)) {
+    return getObjCMethodCall(ME, State, LC);
+  } else {
+    return nullptr;
+  }
+}