Request for review: 7168280: Eliminate the generic signature index slot from field array for field without generic signature

[Jiangli Zhou]

Hi Dean,

Here is the updated webrev 
http://cr.openjdk.java.net/~jiangli/7168280/webrev.01/. In 
init_generic_signature_start_slot(), it first scans from f[0] to 
f[_index - 1] so the generic signature slots for those fields can be 
skipped while scanning from f[_index] to the end.

Thanks again,

Jiangli

On 05/11/2012 01:53 PM, Jiangli Zhou wrote:
> Hi Dean,
>
> Good catch! Thanks for the comments.
>
> Jiangli
>
> On 05/11/2012 01:38 PM, Dean Long wrote:
>> I think this breaks InternalFieldStream. The loop in 
>> init_generic_signature_start_slot() will start at java_fields_count() 
>> instead of 0, so it won't decrement "length" for any Java fields with 
>> a generic signature, resulting in scanning too many elements.
>>
>> dl
>>
>> On 5/11/2012 12:02 PM, Jiangli Zhou wrote:
>>> Hi,
>>>
>>> The field array is an array of 7-shorts [access, name index, sig 
>>> index, initval index, low offset, high offset, generic signature 
>>> index]. Most fields don't have generic signature attribute, in that 
>>> case the generic signature index in the field array is 0 and unused. 
>>> For all classes in rt.jar, there are total about 28973 fields. From 
>>> which 27466 fields do not have generic signature and only 1507 
>>> fields have generic signature.
>>>
>>> Following is a webrev that eliminates the unused generic signature 
>>> index slot from field array. For field without generic signature, 
>>> the field data is 6-shorts. For field with generic signature, it is 
>>> still 7-shorts of data. A new flag is added in the field access flag 
>>> to indicate if the field has the extra short for generic signature 
>>> index.
>>>
>>>   http://cr.openjdk.java.net/~jiangli/7168280/webrev.00/
>>>
>>> Thanks,
>>>
>>> Jiangli
>