RFR(M) 8208999 Some use of Klass* should be replaced by InstanceKlass*

[Ioi Lam]

On 8/6/18 3:40 PM, David Holmes wrote:
> Hi Ioi,
>
> I took a quick look at this but it is not a review. This seems to 
> highlight further problems in the arrangement of types and methods to 
> me. For example in klass.cpp we have:
>
>   bool Klass::verify_itable_index(int i) {
>     assert(is_instance_klass(), "");
> !   int method_count = 
> klassItable::method_count_for_interface(InstanceKlass::cast(this));
>     assert(i >= 0 && i < method_count, "index out of bounds");
>     return true;
>   }
>
> but if "this" must be an instanceKlass then verify_itable_index should 
> not be a method in klass but a method in instanceKlass.
>
Hi David,

Thanks for spotting this. I've move this function to InstanceKlass. 
Updated webrev:

http://cr.openjdk.java.net/~iklam/jdk12/8208999_klass_should_be_instanceklass.v02/

Thanks
- Ioi

> Cheers,
> David
>
> On 7/08/2018 7:26 AM, Ioi Lam wrote:
>> Hi, please review this clean up
>>
>> https://bugs.openjdk.java.net/browse/JDK-8208999
>> http://cr.openjdk.java.net/~iklam/jdk12/8208999_klass_should_be_instanceklass.v01/ 
>>
>>
>> I changed the following APIs so that we can avoid many unnecessary 
>> type casts
>> from Klass* -> InstanceKlass*.
>>
>>      Klass::java_super()                    -> now returns 
>> InstanceKlass*
>>      InstanceKlass::local_interfaces()      -> Array<InstanceKlass*>*
>>      InstanceKlass::transitive_interfaces() -> Array<InstanceKlass*>*
>>
>> I also modified APIs in SystemSictionary and SystemSictionary to 
>> return InstanceKlass*
>> where possible.
>>
>> Most changes are mundane, but here are some notable changes:
>>
>> 1. To save space, Klass::_secondary_supers (an Array<Klass*>*) may be 
>> pointing
>>     to the same array as InstanceKlass::_transitive_interfaces (an
>>     Array<InstanceKlass*>*).
>>
>>     To make this happen, I added Array::as_const_array_of().
>>     See InstanceKlass::compute_secondary_supers() and array.h.
>>
>>     I've added enough 'const' and asserts to catch mis-uses of this type
>>     of casting. If someone has a better suggestion, please let me know.
>>
>> 2. I changed Klass::_secondary_supers to 'const Array<Klass*>*' because
>>     of #1.
>>
>>     There are many pointers returned by Klass/InstanceKlass that 
>> should be
>>     'const', as most callers should read them only without modifying, 
>> but that's
>>     outside the scope of this RFE.
>>
>> 3. SystemDictionary::resolve_super_or_fail() currently accepts the 
>> format
>>     of "Ljava/lang/Object;" for the "super_name" parameter. I am 
>> keeping the
>>     same behavior in my patch. However, I wonder if this actually 
>> correct
>>     per JVMLS. I filed JDK-8209030.
>>
>>     See the call to resolve_instance_class_or_null_helper from 
>> resolve_super_or_fail.
>>
>>
>> Testing: hs tiers 1/2/3/4
>>
>> Thanks
>> - Ioi