@Override
public Node leave(Node parent, Node old, Node n, NodeVisitor v) {
// do context bookkeeping first
if (old instanceof X10MethodDecl) {
assert ((X10MethodDecl) old).returnType().type() == returnType.peek();
returnType.pop();
}
// NB: for calls and closure calls, the rules for boxing are complicated,
// so we insert a simple Cast AST node, so that codegen makes a decision
// whether to do boxing/unboxing. The goal is to ensure, that
// the only places, where codegen needs to consider boxing/unboxing
// are:
// * casts
// * method or closure call arguments
// Generic methods (return type T) can return boxed values (e.g., x10.core.UInt)
// but in the type instantiated [UInt] subclass it is treated as unboxed int.
// We need to insert explicit cast to
// an unboxed type, so that proper conversion method call is inserted later.
if (n instanceof X10Call && !(parent instanceof Eval)) {
X10Call call = (X10Call) n;
Receiver target = call.target();
MethodInstance mi = call.methodInstance();
Type expectedReturnType = call.type();
// do not insert cast the expected type is already boxed or is void
if (X10PrettyPrinterVisitor.isBoxedType(expectedReturnType)
|| expectedReturnType.isVoid() // (void) never needs boxing
// or if the method def type is void -- it is a synthetic method without a proper
// definition
|| mi.def().returnType().get().isVoid()) return n;
if (X10PrettyPrinterVisitor.isBoxedType(mi.def().returnType().get())) {
// only insert cast if the actual returned type is boxed
return cast(call, expectedReturnType);
}
}
// Closures may be implemented by methods returning boxed or unboxed values,
// depending on some involved condition that is checked in codegen.
// So add the dummy type cast to give the codegen
// chance to handle unboxing in a single place
if (n instanceof ClosureCall && !(parent instanceof Eval) && !(parent instanceof Cast)) {
ClosureCall call = (ClosureCall) n;
// if the return type is not primitive, then unboxing will not be needed
if (X10PrettyPrinterVisitor.isBoxedType(call.type()) || call.type().isVoid()) return n;
return cast(call, call.type());
}
if (n instanceof Expr) { // boxing may be needed only for expressions
Expr expr = (Expr) n;
// parent node still has "old" as its child
if (isBoxed(expr) && expectsUnboxed(parent, old)) {
return unbox(expr);
} else if (isUnboxed(expr) && expectsBoxed(parent, old)) {
return box(expr);
}
}
return n;
}
private boolean isBoxedType(Type type) {
if (type == null) return false;
return X10PrettyPrinterVisitor.isBoxedType(type);
}