Zend: use zend_object* for zend_closure this_ptr field

[Girgias]

The main motivation was to convert Z_PARAM_OBJECT{_OR_NULL} to Z_PARAM_OBJ{_OR_NULL}, but I do think working with a zend_object* makes the code more legible and there are no question if this zval can ever be a different type.

Not fully certain about the JIT changes, as maybe the double load is inefficient?

[DanielEScherzer]

okay for ext/reflection, two suggestions elsewhere

[DanielEScherzer]

seems like this is doing an unnecessary setup of instance only to extract the object that we already have

Suggested change

	zval instance;
	ZVAL_OBJ(&instance, Z_OBJ(call->This));
	zend_create_fake_closure(return_value, mptr, mptr->common.scope, Z_OBJCE(instance), &instance);
	zend_create_fake_closure(return_value, mptr, mptr->common.scope, Z_OBJCE(instance), Z_OBJ(instance));
	zend_create_fake_closure(return_value, mptr, mptr->common.scope, Z_OBJCE(call->This), Z_OBJ(call->This));

[Girgias]

I thought so too, but in reality it is needed to preserve the "this" of the current frame (I think) as call->This is pointing to the VM stack.

[DanielEScherzer]

okay, then can I suggest adding a comment to explain that so that others don't try to do the simplification that looked obvious to me?

[Girgias]

Okay, turns out it no longer gives test failures so I'll drop it.

[arnaud-lb]

Not fully certain about the JIT changes, as maybe the double load is inefficient?

These look right. The double load appears to be optimized out, but for clarity it would be worth it to de-duplicate. Also it looks like that the line object_or_called_scope = ir_LOAD_A(ir_ADD_OFFSET(func_ref, offsetof(zend_closure, called_scope))); could be moved in a ir_FALSE(if_cond), but that's not really related to this PR.

[arnaud-lb]

Looks good to me otherwise