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
diff --git a/lib/Frontend/PCHReaderStmt.cpp b/lib/Frontend/PCHReaderStmt.cpp
index 60318de..d253654 100644
--- a/lib/Frontend/PCHReaderStmt.cpp
+++ b/lib/Frontend/PCHReaderStmt.cpp
@@ -782,25 +782,42 @@
unsigned PCHStmtReader::VisitObjCMessageExpr(ObjCMessageExpr *E) {
VisitExpr(E);
- E->setNumArgs(Record[Idx++]);
+ assert(Record[Idx] == E->getNumArgs());
+ ++Idx;
+ ObjCMessageExpr::ReceiverKind Kind
+ = static_cast<ObjCMessageExpr::ReceiverKind>(Record[Idx++]);
+ switch (Kind) {
+ case ObjCMessageExpr::Instance:
+ E->setInstanceReceiver(
+ cast_or_null<Expr>(StmtStack[StmtStack.size() - E->getNumArgs() - 1]));
+ break;
+
+ case ObjCMessageExpr::Class:
+ E->setClassReceiver(Reader.GetTypeSourceInfo(Record, Idx));
+ break;
+
+ case ObjCMessageExpr::SuperClass:
+ case ObjCMessageExpr::SuperInstance: {
+ QualType T = Reader.GetType(Record[Idx++]);
+ SourceLocation SuperLoc = SourceLocation::getFromRawEncoding(Record[Idx++]);
+ E->setSuper(SuperLoc, T, Kind == ObjCMessageExpr::SuperInstance);
+ break;
+ }
+ }
+
+ assert(Kind == E->getReceiverKind());
+
+ if (Record[Idx++])
+ E->setMethodDecl(cast_or_null<ObjCMethodDecl>(Reader.GetDecl(Record[Idx++])));
+ else
+ E->setSelector(Reader.GetSelector(Record, Idx));
+
E->setLeftLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
E->setRightLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
- E->setSelector(Reader.GetSelector(Record, Idx));
- E->setMethodDecl(cast_or_null<ObjCMethodDecl>(Reader.GetDecl(Record[Idx++])));
-
- E->setReceiver(
- cast_or_null<Expr>(StmtStack[StmtStack.size() - E->getNumArgs() - 1]));
- if (!E->getReceiver()) {
- ObjCMessageExpr::ClassInfo CI;
- CI.Decl = cast_or_null<ObjCInterfaceDecl>(Reader.GetDecl(Record[Idx++]));
- CI.Name = Reader.GetIdentifierInfo(Record, Idx);
- CI.Loc = SourceLocation::getFromRawEncoding(Record[Idx++]);
- E->setClassInfo(CI);
- }
for (unsigned I = 0, N = E->getNumArgs(); I != N; ++I)
E->setArg(I, cast<Expr>(StmtStack[StmtStack.size() - N + I]));
- return E->getNumArgs() + 1;
+ return E->getNumArgs() + (Kind == ObjCMessageExpr::Instance);
}
unsigned PCHStmtReader::VisitObjCSuperExpr(ObjCSuperExpr *E) {
@@ -1195,7 +1212,8 @@
S = new (Context) ObjCImplicitSetterGetterRefExpr(Empty);
break;
case pch::EXPR_OBJC_MESSAGE_EXPR:
- S = new (Context) ObjCMessageExpr(Empty);
+ S = ObjCMessageExpr::CreateEmpty(*Context,
+ Record[PCHStmtReader::NumExprFields]);
break;
case pch::EXPR_OBJC_SUPER_EXPR:
S = new (Context) ObjCSuperExpr(Empty);