Request for review: 8003848: Make ConstMethod::generic_signature_index optional and move Method::_max_stack to ConstMethod

[Jiangli Zhou]

Hi Coleen,

Thanks. Will do.

Jiangli

On 11/27/2012 10:37 AM, Coleen Phillimore wrote:
>
> Hi Jiangli,
>
> On 11/27/2012 11:06 AM, Jiangli Zhou wrote:
>> Hi Coleen,
>>
>> I remember now you suggested moving those fields as well when I 
>> proposed the change. I'll move max_locals and size_of_parameters into 
>> constMethod. Would it be okay if I push this as is and work on the 
>> other two fields on the same time?
>
> Sure, that is fine.  Can you file a bug for it?  I don't think there 
> is one yet.
> Thanks,
> Coleen
>
>>
>> Thanks!
>> Jiangli
>>
>> On 11/26/2012 07:35 PM, Coleen Phillimore wrote:
>>>
>>> Jiangli,
>>>
>>> This code looks fine, although I don't like that max_stack is being 
>>> moved without moving max_locals.   They're usually used together in 
>>> the same place.   If you moved max_locals and size_of_parameters 
>>> also with this change into constMethod, I think it would be 
>>> better.   Also, we want to move these fields anyway for more sharing 
>>> with CDS.
>>>
>>> Thanks,
>>> Coleen
>>>
>>> On 11/26/2012 9:08 PM, serguei.spitsyn at oracle.com wrote:
>>>> Jiangli,
>>>>
>>>> It looks good.
>>>>
>>>> Thanks,
>>>> Serguei
>>>>
>>>> On 11/21/12 11:53 AM, Jiangli Zhou wrote:
>>>>> Hi,
>>>>>
>>>>> Please review the following memory reduction change for Method and 
>>>>> ConstMethod:
>>>>>
>>>>>   http://cr.openjdk.java.net/~jiangli/8003848/webrev/
>>>>>
>>>>> Majority of java methods do not have generic signature. For those 
>>>>> methods, ConstMethod::generic_signature_index are always 0. 
>>>>> ConstMethod::generic_signature_index can be optional and only 
>>>>> allocated for methods with generic signature.
>>>>>
>>>>> The Method class has 2-byte unused due to padding for alignment. 
>>>>> Method::_max_stack can be moved to ConstMethod after changing 
>>>>> ConstMethod::generic_signature_index to be optionally allocated. 
>>>>> This removes an u2 field in Method, and can avoid the 2-byte 
>>>>> unused space waste due to padding.
>>>>>
>>>>> Together, above would save 4-bytes for each java method without 
>>>>> generic signature.
>>>>>
>>>>> Tested with jprt, runthese and vm.quick.testlist. No measurable 
>>>>> performance difference with the change for specjvm98 and specjbb2005.
>>>>>
>>>>> ============================================================================== 
>>>>>
>>>>> logs.method_baseline.jbb:
>>>>>   Benchmark           Samples        Mean     Stdev Geomean Weight
>>>>>   specjbb2005               3    56252.53    284.79
>>>>> ============================================================================== 
>>>>>
>>>>> logs.method.jbb.1:
>>>>>   Benchmark           Samples        Mean     Stdev   %Diff P 
>>>>> Significant
>>>>>   specjbb2005               3    56350.15    626.79    0.17 
>>>>> 0.823            *
>>>>> ============================================================================== 
>>>>>
>>>>>
>>>>> ============================================================================== 
>>>>>
>>>>> logs.method_baseline.spec:
>>>>>   Benchmark           Samples        Mean     Stdev Geomean Weight
>>>>>   specjvm98                 8      543.39     11.93
>>>>> ============================================================================== 
>>>>>
>>>>> logs.method.spec.1:
>>>>>   Benchmark           Samples        Mean     Stdev   %Diff P 
>>>>> Significant
>>>>>   specjvm98                 8      544.21      9.56    0.15 
>>>>> 0.881            *
>>>>> ============================================================================== 
>>>>>
>>>>>
>>>>>
>>>>> Thanks,
>>>>> Jiangli
>>>>
>>>
>>
>