[Vm-dev] Re: [Pharo-project] VM problem?

[Mariano Martinez Peck]

> More than that, since CompiledMethod redefines #=, it is strange that
> it's not redefines #hash as well,
> because it is one of requirements to make sure they are always in sync.
>
>
indeed!


>
> > Two conclusions:
> >
> > The solution is to define CompiledMethod>hash such that it does not
> access bytes < initialPC.  The hash it is inheriting from ByteArray is fine
> for ByteArray but not at all OK for CompiledMethod.
> >
> Yes, i would just do
>
> self methodClass hash bitXor: self selector hash
>
>
that's one possibility. If we want to continue with the previous kind of
hash we also could do something like:

CompiledMethod >> hash
    "#hash is implemented, because #= is implemented"

    ^self class
        hashBytes: self bytecodes
        startingWith: self species hash


CompiledMethod >> bytecodes
    | initialPC endPC bytecodes |
    initialPC := self initialPC.
    endPC := self endPC.
    bytecodes := ByteArray new: (endPC - initialPC + 1).
    initialPC to: endPC do: [:index |
        bytecodes at: (index - initialPC + 1) put: (self at: index)
        ].
    ^ bytecodes


I am not a hashing expert. What do you think? which impl should we do?




-- 
Mariano
http://marianopeck.wordpress.com
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