I recently added a rehashAll in Kernel postscript due to a change in
dataAndTime>>hash

Nicolas

2012/5/30 Eliot Miranda <eliot.miranda at gmail.com>:
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> On Sun, May 27, 2012 at 8:37 PM, Levente Uzonyi <leves at elte.hu> wrote:
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>> It's a bit dangerous to change the hash without rehashing the collections
>> which contain CompiledMethods as keys. For example DebuggerMethodMap's
>> MapCache uses CompiledMethods as keys.
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> Good point.  I'll fix this when I fix the methods comment ( COmpiledmethod
> => CompiledMethod)
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>>
>>
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>> Levente
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>> On Sun, 27 May 2012, commits at source.squeak.org wrote:
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>>> Eliot Miranda uploaded a new version of Kernel to project The Trunk:
>>> http://source.squeak.org/trunk/Kernel-eem.692.mcz
>>>
>>> ==================== Summary ====================
>>>
>>> Name: Kernel-eem.692
>>> Author: eem
>>> Time: 27 May 2012, 3:08:41.389 pm
>>> UUID: 72f75218-3cfc-4575-b159-8de0e44aa479
>>> Ancestors: Kernel-nice.691
>>>
>>> Implement CompiledMethod>>#hash, both to accord with
>>> CompiledMethod>>#= and to override ByteArray>>#hash
>>> which looks at all bytes of the receiver and hence may
>>> produce a variable hash if the GC moves literals in a method.
>>>
>>> =============== Diff against Kernel-nice.691 ===============
>>>
>>> Item was added:
>>> + ----- Method: CompiledMethod>>hash (in category 'comparing') -----
>>> + hash
>>> +       "CompiledMethod>>#= compares code, i.e. same literals and same
>>> bytecode.
>>> +        So we look at the header, methodClass and some bytes between
>>> initialPC and endPC,
>>> +        but /not/ the selector because the equal method does not compare
>>> selectors.
>>> +        Note that we must override ByteArray>hash which looks at all
>>> bytes of the receiver.
>>> +        Using bytes from the pointer part of a COmpiledmethod can lead
>>> to a variable hash
>>> +        if and when when the GC moves literals in the receiver."
>>> +       | initialPC endPC hash |
>>> +       initialPC := self initialPC.
>>> +       endPC := self endPC.
>>> +       hash := self species hash + self header + initialPC + endPC +
>>> self methodClass hash bitAnd: 16rFFFFFFF.
>>> +       "sample approximately 20 bytes"
>>> +       initialPC to: endPC by: (endPC - initialPC // 20 max: 1) do:
>>> +               [:i| hash := hash + (self at: i)].
>>> +       ^hash
>>> +
>>> +       "(CompiledMethod>>#hash) hash"!
>>>
>>>
>>>
>>
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> --
> best,
> Eliot
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