/**
* Emit bytecode for the selectAlternative idiom.
*
* The pattern looks like (Cf. MethodHandleImpl.makeGuardWithTest):
* <blockquote><pre>{@code
* Lambda(a0:L,a1:I)=>{
* t2:I=foo.test(a1:I);
* t3:L=MethodHandleImpl.selectAlternative(t2:I,(MethodHandle(int)int),(MethodHandle(int)int));
* t4:I=MethodHandle.invokeBasic(t3:L,a1:I);t4:I}
* }</pre></blockquote>
*/
private Name emitSelectAlternative(Name selectAlternativeName, Name invokeBasicName)
{
//assert isStaticallyInvocable(invokeBasicName);
Name receiver = (Name)invokeBasicName.arguments[0];
CodeEmitterLabel L_fallback = ilgen.DefineLabel();
CodeEmitterLabel L_done = ilgen.DefineLabel();
// load test result
emitPushArgument(selectAlternativeName, 0);
// if_icmpne L_fallback
ilgen.EmitBrfalse(L_fallback);
// invoke selectAlternativeName.arguments[1]
//Class<?>[] preForkClasses = localClasses.clone();
emitPushArgument(selectAlternativeName, 1); // get 2nd argument of selectAlternative
emitAstoreInsn(receiver.index()); // store the MH in the receiver slot
emitStaticInvoke(invokeBasicName);
// goto L_done
ilgen.EmitBr(L_done);
// L_fallback:
ilgen.MarkLabel(L_fallback);
// invoke selectAlternativeName.arguments[2]
//System.arraycopy(preForkClasses, 0, localClasses, 0, preForkClasses.length);
emitPushArgument(selectAlternativeName, 2); // get 3rd argument of selectAlternative
emitAstoreInsn(receiver.index()); // store the MH in the receiver slot
emitStaticInvoke(invokeBasicName);
// L_done:
ilgen.MarkLabel(L_done);
// for now do not bother to merge typestate; just reset to the dominator state
//System.arraycopy(preForkClasses, 0, localClasses, 0, preForkClasses.length);
return(invokeBasicName); // return what's on stack
}
internal override void Emit(CodeEmitter ilgen, CodeEmitterLabel label)
{
ilgen.EmitBr(label);
}
