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

[Dean Long]

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