Value array flattening in L-world
david.simms at oracle.com
Thu Feb 22 18:23:50 UTC 2018
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)
> stack=2, locals=2, args_size=2
> 0: aload_0
> 1: getfield #2 // Field
> 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
> 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.
>> (in vacation this week :)
> In that case, excuse my judging, but: "Vacation fail", but I feel
> honoured by your reply...take it easy Remi !
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