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

[Jiangli Zhou]

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