Request for review: 7117052 instanceKlass::_init_state can be u1 type

[Tom Rodriguez]

On Dec 1, 2011, at 10:51 AM, Jiangli Zhou wrote:

> The instanceKlass::_init_state is defined as instanceKlass::ClassState type, which is an enum. Currently there are 7 class states defined. The instanceKlass::_init_state can be changed to u1 type, which could hold up 256 states. There are unused bytes after instanceKlass::_idnum_allocated_count field. Changing _init_state to u1 and move it to after the _idnum_allocate_count field would save 4-byte for each loaded class.

The code in C2 to load it as T_BOOLEAN is somewhat questionable.  In particular typing the result as a TypeInt::BOOL says that it only returns 0 or 1, which is definitely not true.  It should be TypeInt::UBYTE which is the default type of a LoadUBNode.  Using T_BOOLEAN still seems a little wonky but we don't have a BasicType for unsigned byte.

tom

> 
> http://cr.openjdk.java.net/~jiangli/7117052/webrev.00/
> 
> Thanks,
> 
> Jiangli
>