On Wed, 18 May 2022 14:21:55 GMT, Maurizio Cimadamore <[email protected]>
wrote:
>> I'm not sure if there is anything actionable here?
>>
>> I've thought in the past that it might be nice to have
>> `GetArgument`/`SetArgument` and `GetReturnValue`/`SetReturnValue` binding
>> operators as well, to make the inputs/outputs more explicit in the recipe.
>> But, it doesn't seem like that would make things _much_ better...
>
> I wasn't suggesting to add more bindings. I was more suggesting to filter out
> the load/store from the set of bindings (since these are virtualized anyways)
> that are passed to `doBindings`. Then, before executing a set of bindings,
> (if we are in downcall mode) we load the corresponding input local var. After
> executing bindings (if we are in upcall mode) we store result in
> corresponding var.
>
> E.g. make the logic that load locals and store locals explicit in the
> `specialize` method, rather than have parts of it execute "in disguise" as
> "binding interpretation".
It's not quite that simple since a binding recipe for a single parameter can
have multiple VMStores for instance if a struct is decomposed into multiple
values.
It can be done by pulling the binding loops up to the `specialize` method, and
have if statements for VMStore and VMLoad, like this:
for (Binding binding : callingSequence.argumentBindings(i)) {
if (binding instanceof Binding.VMStore vms &&
callingSequence.forDowncall()) {
emitSetOutput(vms.type());
} else if (binding instanceof Binding.VMLoad &&
callingSequence.forUpcall()) {
emitGetInput();
} else {
doBinding(binding);
}
}
And for returns:
for (Binding binding : callingSequence.returnBindings()) {
if (binding instanceof Binding.VMLoad vml &&
callingSequence.forDowncall()) {
if (!callingSequence.needsReturnBuffer()) {
emitRestoreReturnValue(vml.type());
} else {
emitReturnBufferLoad(vml);
}
} else if (binding instanceof Binding.VMStore vms &&
callingSequence.forUpcall()) {
if (!callingSequence.needsReturnBuffer()) {
emitSaveReturnValue(vms.type());
} else {
emitReturnBufferStore(vms);
}
} else {
doBinding(binding);
}
}
But, maybe that's better?
-------------
PR: https://git.openjdk.java.net/jdk/pull/8685
