Value array flattening in L-world

[David Simms]

And then "defaultvalue" is "null", so this excludes 'defaultvalue' from 
being a valid value in legacy code...might not be true at all.


On 22/02/18 19:16, David Simms wrote:
>
> So without changing legacy code, modify:
>
> * aastore: accept null TOS (top of stack) as default - checks out, 
> bytecode understands receiveras flat value array
> * ifnonnull: accept "default" as null, i.e.: What ever TOS is 
> conditional upon...wait what, interpreter is a little too simple for 
> "source was value array"
> ** Need to tag TOS as vt in interpreter runtime ? Could work.
>
>
>   boolean isEmpty(int);
>     descriptor: (I)Z
>     flags: (0x0000)
>     Code:
>       stack=2, locals=2, args_size=2
>          0: aload_0
>          1: getfield      #2                  // Field 
> elemData:[Ljava/lang/Object;
>          4: iload_1
>          5: aaload
>          6: ifnonnull     13                  // Feels not quite 
> right, that memcmp(defaultvalue, ) return
>          9: iconst_1
>         10: goto          14
>         13: iconst_0
>         14: ireturn
>
>
> This idea is interesting, TOS type problem for ifnonnull is "fun", but 
> doable.
>
> What else have we missed ?
>
>
> On 22/02/18 18:29, Remi Forax wrote:
>> One solution is to consider that doesn't mean literally null like 
>> Object doesn't mean ref anymore.
>>
>> In that case, null means default value and remove() and isEmpty() works.
>>
>> If we go with this semantics, we may also have to revisit the 
>> semantics of putfield with null.
>>
>> Remi
>> (in vacation this week :)
>
> In that case, excuse my judging, but: "Vacation fail", but I feel 
> honoured by your reply...take it easy Remi !
>
> /D
>
>