Both value and primitive classes use the aconst_init / withfield
initialization protocol. The former is an L-type (QOptional is
illegal); the latter uses Q types for initialization.
Value classes
-> are L types
-> which are references
-> references can be null
-> VM manages where the nullity bits are
so for value classes, there has to be some way of starting the ball
rolling with an uninitialized, but non-null, value. We can then modify
the fields (but not the nullity) with `withfield`.
On 1/12/2022 7:31 AM, Remi Forax wrote:
I've some troubles to wrap my head around those two sentences
"""
aconst_init is the analogue of new for value objects; it leaves a reference to
the initial value for a value class on the stack. This initial value is
guaranteed to not be equal to null. The sole operand of this bytecode is a
reference to a CONSTANT_Class item giving the internal binary name of the value
class (not its Q descriptor).
"""
and
"""
Both withfield and aconst_init return a Q type if and only if their class is a
primitive class.
"""
The second is ambiguous because it's not clear if aconst_init can return a
L-type. I suppose it can not but this is not clear at all.
If this is the case, what is the use case for withfield taking a L-type as
parameter ??
regards,
Rémi
