Overhaul the AST representation of Objective-C message send

expressions, to improve source-location information, clarify the
actual receiver of the message, and pave the way for proper C++
support. The ObjCMessageExpr node represents four different kinds of
message sends in a single AST node:

  1) Send to a object instance described by an expression (e.g., [x method:5])
  2) Send to a class described by the class name (e.g., [NSString method:5])
  3) Send to a superclass class (e.g, [super method:5] in class method)
  4) Send to a superclass instance (e.g., [super method:5] in instance method)

Previously these four cases where tangled together. Now, they have
more distinct representations. Specific changes:

  1) Unchanged; the object instance is represented by an Expr*.

  2) Previously stored the ObjCInterfaceDecl* referring to the class
  receiving the message. Now stores a TypeSourceInfo* so that we know
  how the class was spelled. This both maintains typedef information
  and opens the door for more complicated C++ types (e.g., dependent
  types). There was an alternative, unused representation of these
  sends by naming the class via an IdentifierInfo *. In practice, we
  either had an ObjCInterfaceDecl *, from which we would get the
  IdentifierInfo *, or we fell into the case below...

  3) Previously represented by a class message whose IdentifierInfo *
  referred to "super". Sema and CodeGen would use isStr("super") to
  determine if they had a send to super. Now represented as a
  "class super" send, where we have both the location of the "super"
  keyword and the ObjCInterfaceDecl* of the superclass we're
  targetting (statically).

  4) Previously represented by an instance message whose receiver is a
  an ObjCSuperExpr, which Sema and CodeGen would check for via
  isa<ObjCSuperExpr>(). Now represented as an "instance super" send,
  where we have both the location of the "super" keyword and the
  ObjCInterfaceDecl* of the superclass we're targetting
  (statically). Note that ObjCSuperExpr only has one remaining use in
  the AST, which is for "super.prop" references.

The new representation of ObjCMessageExpr is 2 pointers smaller than
the old one, since it combines more storage. It also eliminates a leak
when we loaded message-send expressions from a precompiled header. The
representation also feels much cleaner to me; comments welcome!

This patch attempts to maintain the same semantics we previously had
with Objective-C message sends. In several places, there are massive
changes that boil down to simply replacing a nested-if structure such
as:

  if (message has a receiver expression) {
    // instance message
    if (isa<ObjCSuperExpr>(...)) {
     // send to super
    } else {
     // send to an object
   }
  } else {
    // class message
    if (name->isStr("super")) {
      // class send to super
    } else {
      // send to class
    }
  }

with a switch

  switch (E->getReceiverKind()) {
  case ObjCMessageExpr::SuperInstance: ...
  case ObjCMessageExpr::Instance: ...
  case ObjCMessageExpr::SuperClass: ...
  case ObjCMessageExpr::Class:...
  }

There are quite a few places (particularly in the checkers) where
send-to-super is effectively ignored. I've placed FIXMEs in most of
them, and attempted to address send-to-super in a reasonable way. This
could use some review.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@101972 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 77 insertions, 36 deletions

diff --git a/lib/Checker/CFRefCount.cpp b/lib/Checker/CFRefCount.cpp
index a0b4666160..d26ee1db56 100644
--- a/lib/Checker/CFRefCount.cpp
+++ b/lib/Checker/CFRefCount.cpp
@@ -603,12 +603,33 @@ public:
 
     Selector S = ME->getSelector();
 
-    if (Expr* Receiver = ME->getReceiver()) {
-      const ObjCInterfaceDecl* OD = getReceiverDecl(Receiver);
-      return OD ? M[ObjCSummaryKey(OD->getIdentifier(), S)] : M[S];
+    const ObjCInterfaceDecl* OD = 0;
+    bool IsInstanceMessage = false;
+    switch (ME->getReceiverKind()) {
+    case ObjCMessageExpr::Instance:
+      OD = getReceiverDecl(ME->getInstanceReceiver());
+      IsInstanceMessage = true;
+      break;
+
+    case ObjCMessageExpr::SuperInstance:
+      IsInstanceMessage = true;
+      OD = ME->getSuperType()->getAs<ObjCObjectPointerType>()
+                                                        ->getInterfaceDecl();
+      break;
+
+    case ObjCMessageExpr::Class:
+      OD = ME->getClassReceiver()->getAs<ObjCInterfaceType>()->getDecl();
+      break;
+
+    case ObjCMessageExpr::SuperClass:
+      OD = ME->getSuperType()->getAs<ObjCInterfaceType>()->getDecl();
+      break;
     }
 
-    return M[ObjCSummaryKey(ME->getClassName(), S)];
+    if (IsInstanceMessage)
+      return OD ? M[ObjCSummaryKey(OD->getIdentifier(), S)] : M[S];
+
+    return M[ObjCSummaryKey(OD->getIdentifier(), S)];
   }
 
   RetainSummary*& operator[](ObjCSummaryKey K) {
@@ -836,7 +857,7 @@ public:
   
   RetainSummary* getInstanceMethodSummary(const ObjCMessageExpr* ME,
                                           const ObjCInterfaceDecl* ID) {
-    return getInstanceMethodSummary(ME->getSelector(), ME->getClassName(),
+    return getInstanceMethodSummary(ME->getSelector(), 0,
                             ID, ME->getMethodDecl(), ME->getType());
   }
 
@@ -851,8 +872,21 @@ public:
                                        QualType RetTy);
 
   RetainSummary *getClassMethodSummary(const ObjCMessageExpr *ME) {
-    return getClassMethodSummary(ME->getSelector(), ME->getClassName(),
-                                 ME->getClassInfo().Decl,
+    ObjCInterfaceDecl *Class = 0;
+    switch (ME->getReceiverKind()) {
+    case ObjCMessageExpr::Class:
+    case ObjCMessageExpr::SuperClass:
+      Class = ME->getReceiverInterface();
+      break;
+
+    case ObjCMessageExpr::Instance:
+    case ObjCMessageExpr::SuperInstance:
+      break;
+    }
+
+    return getClassMethodSummary(ME->getSelector(), 
+                                 Class? Class->getIdentifier() : 0,
+                                 Class,
                                  ME->getMethodDecl(), ME->getType());
   }
 
@@ -1333,37 +1367,44 @@ RetainSummaryManager::getInstanceMethodSummary(const ObjCMessageExpr *ME,
 
   // We need the type-information of the tracked receiver object
   // Retrieve it from the state.
-  const Expr *Receiver = ME->getReceiver();
+  const Expr *Receiver = ME->getInstanceReceiver();
   const ObjCInterfaceDecl* ID = 0;
 
   // FIXME: Is this really working as expected?  There are cases where
   //  we just use the 'ID' from the message expression.
-  SVal receiverV = state->getSValAsScalarOrLoc(Receiver);
+  SVal receiverV;
+
+  if (const Expr *Receiver = ME->getInstanceReceiver()) {
+    receiverV = state->getSValAsScalarOrLoc(Receiver);
   
-  // FIXME: Eventually replace the use of state->get<RefBindings> with
-  // a generic API for reasoning about the Objective-C types of symbolic
-  // objects.
-  if (SymbolRef Sym = receiverV.getAsLocSymbol())
-    if (const RefVal *T = state->get<RefBindings>(Sym))
-      if (const ObjCObjectPointerType* PT = 
+    // FIXME: Eventually replace the use of state->get<RefBindings> with
+    // a generic API for reasoning about the Objective-C types of symbolic
+    // objects.
+    if (SymbolRef Sym = receiverV.getAsLocSymbol())
+      if (const RefVal *T = state->get<RefBindings>(Sym))
+        if (const ObjCObjectPointerType* PT = 
             T->getType()->getAs<ObjCObjectPointerType>())
-        ID = PT->getInterfaceDecl();
+          ID = PT->getInterfaceDecl();
   
-  // FIXME: this is a hack.  This may or may not be the actual method
-  //  that is called.
-  if (!ID) {
-    if (const ObjCObjectPointerType *PT =
-        Receiver->getType()->getAs<ObjCObjectPointerType>())
-      ID = PT->getInterfaceDecl();
+    // FIXME: this is a hack.  This may or may not be the actual method
+    //  that is called.
+    if (!ID) {
+      if (const ObjCObjectPointerType *PT =
+          Receiver->getType()->getAs<ObjCObjectPointerType>())
+        ID = PT->getInterfaceDecl();
+    }
+  } else {
+    // FIXME: Hack for 'super'.
+    ID = ME->getReceiverInterface();
   }
-  
+
   // FIXME: The receiver could be a reference to a class, meaning that
   //  we should use the class method.
   RetainSummary *Summ = getInstanceMethodSummary(ME, ID);
   
   // Special-case: are we sending a mesage to "self"?
   //  This is a hack.  When we have full-IP this should be removed.
-  if (isa<ObjCMethodDecl>(LC->getDecl())) {
+  if (isa<ObjCMethodDecl>(LC->getDecl()) && Receiver) {
     if (const loc::MemRegionVal *L = dyn_cast<loc::MemRegionVal>(&receiverV)) {
       // Get the region associated with 'self'.
       if (const ImplicitParamDecl *SelfDecl = LC->getSelfDecl()) {
@@ -2144,7 +2185,7 @@ PathDiagnosticPiece* CFRefReport::VisitNode(const ExplodedNode* N,
       }
     }
     else if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(S)) {
-      if (const Expr *receiver = ME->getReceiver())
+      if (const Expr *receiver = ME->getInstanceReceiver())
         if (CurrSt->getSValAsScalarOrLoc(receiver).getAsLocSymbol() == Sym) {
           // The symbol we are tracking is the receiver.
           AEffects.push_back(Summ->getReceiverEffect());
@@ -2510,7 +2551,7 @@ static QualType GetReturnType(const Expr* RetE, ASTContext& Ctx) {
         // id, id<...>, or Class. If we have an ObjCInterfaceDecl, we know this
         // is a call to a class method whose type we can resolve.  In such
         // cases, promote the return type to XXX* (where XXX is the class).
-        const ObjCInterfaceDecl *D = ME->getClassInfo().Decl;
+        const ObjCInterfaceDecl *D = ME->getReceiverInterface();
         return !D ? RetTy : Ctx.getPointerType(Ctx.getObjCInterfaceType(D));
       }
 
@@ -2660,15 +2701,15 @@ void CFRefCount::EvalSummary(ExplodedNodeSet& Dst,
   RetEffect RE = Summ.getRetEffect();
 
   if (RE.getKind() == RetEffect::OwnedWhenTrackedReceiver) {
-    assert(Receiver);
-    SVal V = state->getSValAsScalarOrLoc(Receiver);
     bool found = false;
-    if (SymbolRef Sym = V.getAsLocSymbol())
-      if (state->get<RefBindings>(Sym)) {
-        found = true;
-        RE = Summaries.getObjAllocRetEffect();
-      }
-
+    if (Receiver) {
+      SVal V = state->getSValAsScalarOrLoc(Receiver);
+      if (SymbolRef Sym = V.getAsLocSymbol())
+        if (state->get<RefBindings>(Sym)) {
+          found = true;
+          RE = Summaries.getObjAllocRetEffect();
+        }
+    } // FIXME: Otherwise, this is a send-to-super instance message.
     if (!found)
       RE = RetEffect::MakeNoRet();
   }
@@ -2802,12 +2843,12 @@ void CFRefCount::EvalObjCMessageExpr(ExplodedNodeSet& Dst,
                                      ExplodedNode* Pred,
                                      const GRState *state) {
   RetainSummary *Summ =
-    ME->getReceiver()
+    ME->isInstanceMessage()
       ? Summaries.getInstanceMethodSummary(ME, state,Pred->getLocationContext())
       : Summaries.getClassMethodSummary(ME);
 
   assert(Summ && "RetainSummary is null");
-  EvalSummary(Dst, Eng, Builder, ME, ME->getReceiver(), *Summ, NULL,
+  EvalSummary(Dst, Eng, Builder, ME, ME->getInstanceReceiver(), *Summ, NULL,
               ME->arg_begin(), ME->arg_end(), Pred, state);
 }