Implement yield* (delegating yield)

src/ia32/full-codegen-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1903 matching lines @@
 
     case Yield::FINAL: {
       VisitForAccumulatorValue(expr->generator_object());
       __ mov(FieldOperand(result_register(),
                           JSGeneratorObject::kContinuationOffset),
              Immediate(Smi::FromInt(JSGeneratorObject::kGeneratorClosed)));
       EmitReturnIteratorResult(true);
       break;
     }
 
-    case Yield::DELEGATING:
-      UNIMPLEMENTED();
+    case Yield::DELEGATING: {
+      VisitForStackValue(expr->generator_object());
+
+      // Initial stack layout is as follows:
+      // [sp + 1 * kPointerSize] iter
+      // [sp + 0 * kPointerSize] g
+
+      Label l_catch, l_try, l_resume, l_send, l_call, l_loop;
+      // Initial send value is undefined.
+      __ mov(eax, isolate()->factory()->undefined_value());
+      __ jmp(&l_send);
+
+      // catch (e) { receiver = iter; f = iter.throw; arg = e; }

[rossberg, 2013/05/13 11:14:56]

...; goto l_call;

+      __ bind(&l_catch);
+      handler_table()->set(expr->index(), Smi::FromInt(l_catch.pos()));
+      __ push(Operand(esp, 1 * kPointerSize));           // iter
+      __ push(eax);                                      // exception
+      __ mov(edx, Operand(esp, 3 * kPointerSize));       // iter

[rossberg, 2013/05/13 11:14:56]

Nit: Why not do this 2 lines earlier and then push edx?

+      __ mov(ecx, isolate()->factory()->throw_string());  // "throw"
+      Handle<Code> throw_ic = isolate()->builtins()->LoadIC_Initialize();
+      CallIC(throw_ic);                                  // iter.throw in eax
+      __ jmp(&l_call);
+
+      // try { received = yield result.value }
+      __ bind(&l_try);
+      __ pop(eax);                                       // result.value
+      __ PushTryHandler(StackHandler::CATCH, expr->index());
+      const int handler_size = StackHandlerConstants::kSize;
+      __ push(eax);                                      // result.value
+      __ push(Operand(esp, (0 + 1) * kPointerSize + handler_size));  // g
+      __ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
+      __ mov(context_register(),
+             Operand(ebp, StandardFrameConstants::kContextOffset));
+      __ CompareRoot(eax, Heap::kTheHoleValueRootIndex);
+      __ j(not_equal, &l_resume);
+      EmitReturnIteratorResult(false);
+      __ bind(&l_resume);                                // received in eax
+      __ PopTryHandler();
+
+      // receiver = iter; f = iter.send; arg = received;
+      __ bind(&l_send);
+      __ push(Operand(esp, 1 * kPointerSize));           // iter
+      __ push(eax);                                      // received
+      __ mov(edx, Operand(esp, 3 * kPointerSize));       // iter

[rossberg, 2013/05/13 11:14:56]

Nit: same here

+      __ mov(ecx, isolate()->factory()->send_string());  // "send"
+      Handle<Code> send_ic = isolate()->builtins()->LoadIC_Initialize();
+      CallIC(send_ic);                                   // iter.send in rax

[rossberg, 2013/05/13 11:14:56]

s/rax/eax/

+
+      // result = f.call(receiver, arg);
+      __ bind(&l_call);
+      Label l_call_runtime;
+      __ JumpIfSmi(eax, &l_call_runtime);
+      __ CmpObjectType(eax, JS_FUNCTION_TYPE, ebx);
+      __ j(not_equal, &l_call_runtime);
+      __ mov(edi, eax);
+      ParameterCount count(1);
+      __ InvokeFunction(edi, count, CALL_FUNCTION,
+                        NullCallWrapper(), CALL_AS_METHOD);
+      __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
+      __ jmp(&l_loop);
+      __ bind(&l_call_runtime);
+      __ push(eax);
+      __ CallRuntime(Runtime::kCall, 3);
+
+      // val = result.value; if (!result.done) goto l_try;
+      __ bind(&l_loop);
+      // result.value
+      __ push(eax);                                      // save result
+      __ mov(edx, eax);                                  // result
+      __ mov(ecx, isolate()->factory()->value_string());  // "value"
+      Handle<Code> value_ic = isolate()->builtins()->LoadIC_Initialize();
+      CallIC(value_ic);                                  // result.value in rax
+      __ pop(ebx);                                       // result
+      __ push(eax);                                      // result.value
+      __ mov(edx, ebx);                                  // result
+      __ mov(ecx, isolate()->factory()->done_string());  // "done"
+      Handle<Code> done_ic = isolate()->builtins()->LoadIC_Initialize();
+      CallIC(done_ic);                                   // result.done in rax
+      ToBooleanStub stub(eax);
+      __ push(eax);
+      __ CallStub(&stub);
+      __ test(eax, eax);
+      __ j(zero, &l_try);
+
+      // result.value
+      __ pop(eax);                                       // result.value
+      context()->DropAndPlug(2, eax);                    // drop iter and g
+      break;
+    }
   }
 }
 
 
 void FullCodeGenerator::EmitGeneratorResume(Expression *generator,
     Expression *value,
     JSGeneratorObject::ResumeMode resume_mode) {
   // The value stays in eax, and is ultimately read by the resumed generator, as
   // if the CallRuntime(Runtime::kSuspendJSGeneratorObject) returned it.  ebx
   // will hold the generator object until the activation has been resumed.
@@ skipping 2804 matching lines @@
   *stack_depth = 0;
   *context_length = 0;
   return previous_;
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32