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.

llvm-svn: 101972

1 files changed, 56 insertions, 23 deletions

diff --git a/clang/lib/Index/Analyzer.cpp b/clang/lib/Index/Analyzer.cpp
index 7b414f2a9fb..1354fe6be0d 100644
--- a/clang/lib/Index/Analyzer.cpp
+++ b/clang/lib/Index/Analyzer.cpp
@@ -153,9 +153,10 @@ public:
     ObjCInterfaceDecl *MsgD = 0;
     ObjCMessageExpr *Msg = cast<ObjCMessageExpr>(ASTLoc.AsStmt());
 
-    if (Msg->getReceiver()) {
+    switch (Msg->getReceiverKind()) {
+    case ObjCMessageExpr::Instance: {
       const ObjCObjectPointerType *OPT =
-          Msg->getReceiver()->getType()->getAsObjCInterfacePointerType();
+          Msg->getInstanceReceiver()->getType()->getAsObjCInterfacePointerType();
 
       // Can be anything! Accept it as a possibility..
       if (!OPT || OPT->isObjCIdType() || OPT->isObjCQualifiedIdType())
@@ -171,15 +172,34 @@ public:
       // Should be an instance method.
       if (!IsInstanceMethod)
         return false;
+      break;
+    }
 
-    } else {
+    case ObjCMessageExpr::Class: {
+      // Expecting class method.
+      if (IsInstanceMethod)
+        return false;
+
+      MsgD = Msg->getClassReceiver()->getAs<ObjCInterfaceType>()->getDecl();
+      break;
+    }
+
+    case ObjCMessageExpr::SuperClass:
       // Expecting class method.
       if (IsInstanceMethod)
         return false;
 
-      MsgD = Msg->getClassInfo().Decl;
-      // FIXME: Case when we only have an identifier.
-      assert(MsgD && "Identifier only");
+      MsgD = Msg->getSuperType()->getAs<ObjCInterfaceType>()->getDecl();
+      break;
+
+    case ObjCMessageExpr::SuperInstance:
+      // Expecting instance method.
+      if (!IsInstanceMethod)
+        return false;
+
+      MsgD = Msg->getSuperType()->getAs<ObjCObjectPointerType>()
+                                                          ->getInterfaceDecl();
+      break;
     }
 
     assert(MsgD);
@@ -248,31 +268,44 @@ public:
     ObjCInterfaceDecl *MsgD = 0;
 
     while (true) {
-      if (Msg->getReceiver() == 0) {
-        CanBeClassMethod = true;
-        MsgD = Msg->getClassInfo().Decl;
-        // FIXME: Case when we only have an identifier.
-        assert(MsgD && "Identifier only");
-        break;
-      }
+      switch (Msg->getReceiverKind()) {
+      case ObjCMessageExpr::Instance: {
+        const ObjCObjectPointerType *OPT =
+          Msg->getInstanceReceiver()->getType()
+                                      ->getAsObjCInterfacePointerType();
+
+        if (!OPT || OPT->isObjCIdType() || OPT->isObjCQualifiedIdType()) {
+          CanBeInstanceMethod = CanBeClassMethod = true;
+          break;
+        }
 
-      const ObjCObjectPointerType *OPT =
-          Msg->getReceiver()->getType()->getAsObjCInterfacePointerType();
+        if (OPT->isObjCClassType() || OPT->isObjCQualifiedClassType()) {
+          CanBeClassMethod = true;
+          break;
+        }
 
-      if (!OPT || OPT->isObjCIdType() || OPT->isObjCQualifiedIdType()) {
-        CanBeInstanceMethod = CanBeClassMethod = true;
+        MsgD = OPT->getInterfaceDecl();
+        assert(MsgD);
+        CanBeInstanceMethod = true;
         break;
       }
+        
+      case ObjCMessageExpr::Class:
+        CanBeClassMethod = true;
+        MsgD = Msg->getClassReceiver()->getAs<ObjCInterfaceType>()->getDecl();
+        break;
 
-      if (OPT->isObjCClassType() || OPT->isObjCQualifiedClassType()) {
+      case ObjCMessageExpr::SuperClass:
         CanBeClassMethod = true;
+        MsgD = Msg->getSuperType()->getAs<ObjCInterfaceType>()->getDecl();
         break;
-      }
 
-      MsgD = OPT->getInterfaceDecl();
-      assert(MsgD);
-      CanBeInstanceMethod = true;
-      break;
+      case ObjCMessageExpr::SuperInstance:
+        CanBeInstanceMethod = true;
+        MsgD = Msg->getSuperType()->getAs<ObjCObjectPointerType>()
+                                                           ->getInterfaceDecl();
+        break;
+      }
     }
 
     assert(CanBeInstanceMethod || CanBeClassMethod);