Re: [rvm-research] A bug in GenCopyMutator

> Hi Dingwen,
>
> I don't really understand what you are saying here.
>
> 1.  Unless you are doing pretenuring, you will never exercise this
> code path.   Are you doing pretenuring?
>
> 2.  The code looks correct to me (it mirrors the code used for the
> collector's allocator which *is* exercised and is correct).
>
> --Steve
>
>
> On 18/06/2009, at 4:30 PM, Dingwen Yuan wrote:
>
>> Hello All,
>>
>> I think I found a bug in GenCopyMutator. The original
>> collectionPhase() in this class is:
>>
>> public void collectionPhase(short phaseId, boolean primary) {
>>    if (global().traceFullHeap()) {
>>      if (phaseId == GenCopy.PREPARE) {
>>        super.collectionPhase(phaseId, primary);
>>        if (global().gcFullHeap) mature.rebind(GenCopy.toSpace());
>>        return;
>>      }
>>    }
>>
>>    super.collectionPhase(phaseId, primary);
>>  }
>>
>> I think the line "if (global().gcFullHeap)
>> mature.rebind(GenCopy.toSpace());" should be moved to the phase
>> RELEASE. Because the PREPARE of mutator comes before the PREPARE of
>> GenCopy, at that time the toSpace is not yet toggled, so we will
>> premature into the old space which is wrong.
>>
>> The original pretenure code made the dacapo benchmarks fail(I've
>> tried antlr, fop, pmd). But they can pass with the modified code.
>>
>> BTW, I worked with version 2.9.2, and I think the bug also exists in
>> later versions.
>>
>> cheers,
>>
>> Dingwen
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>
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