RFR (XL) 8155672: Remove instanceKlassHandles and KlassHandles

Mon Mar 13 12:37:37 UTC 2017

David, I'm so sorry, I should have pointed to

open webrev at http://cr.openjdk.java.net/~coleenp/8155672.02/webrev

On 3/13/17 2:23 AM, David Holmes wrote:
> Hi Coleen,
>
> Wow that was a hard slog! :)
>
> On 13/03/2017 2:18 PM, coleen.phillimore at oracle.com wrote:
>>
>> As requested by David on the closed part of this review, I fixed
>> variable names of the form h_ik and klass_h where the 'h' indicated that
>> the klass was in a handle.
>
> Thanks for that. But I'm afraid there are quite a number of other 
> patterns including the "h" still present:
>
> src/share/vm/aot/aotCodeHeap.cpp/.hpp: InstanceKlass* kh
> src/share/vm/c1/c1_Runtime1.cpp: InstanceKlass* h
> src/share/vm/ci/ciArrayKlass.cpp: Klass* h_k
> src/share/vm/ci/ciInstanceKlass.cpp/.hpp: Klass* h_k
> src/share/vm/ci/ciKlass.cpp/.hpp: Klass* h_k
> src/share/vm/ci/ciMethod.cpp: Klass* h_recv, Klass* h_resolved (though 
> that code uses h_ when there doesn't appear to be a handle in use)
> src/share/vm/ci/ciObjArrayKlass.cpp/.hpp: Klass* h_k
> src/share/vm/ci/ciTypeArrayKlass.cpp/.hpp: Klass* h_k
> src/share/vm/interpreter/interpreterRuntime.cpp: Klass* h_klass, 
> InstanceKlass* h_cp_entry_f1
> src/share/vm/prims/jni.cpp:  Klass* h_k
> src/share/vm/prims/jvm.cpp: InstanceKlass* kh, InstanceKlass* ik_h
> src/share/vm/prims/jvmtiClassFileReconstituter.cpp: InstanceKlass* iikh
> src/share/vm/prims/jvmtiClassFileReconstituter.hpp: InstanceKlass* 
> _ikh, InstanceKlass*  ikh()
> src/share/vm/prims/jvmtiEnv.cpp: InstanceKlass* ikh, InstanceKlass* 
> instanceK_h
> src/share/vm/prims/jvmtiEnvBase.cpp: Klass* ob_kh
> src/share/vm/prims/jvmtiExport.cpp: Klass* _h_class_being_redefined
> src/share/vm/prims/jvmtiImpl.cpp: InstanceKlass* ikh, Klass* ob_kh
> src/share/vm/prims/jvmtiRedefineClasses.cpp: InstanceKlass* ikh
> src/share/vm/prims/jvmtiTagMap.cpp: InstanceKlass* ikh
> src/share/vm/prims/jvmtiThreadState.hpp: Klass* h_class
> src/share/vm/prims/nativeLookup.cpp: Klass* kh
> src/share/vm/prims/whitebox.cpp: InstanceKlass* ikh
> src/share/vm/runtime/sharedRuntime.cpp: Klass* h_klass
> src/share/vm/services/gcNotifier.cpp: InstanceKlass* mu_kh
> src/share/vm/services/heapDumper.cpp: InstanceKlass* ikh
>

These were the ones I fixed and retested.
>
>> open webrev at http://cr.openjdk.java.net/~coleenp/8155672.01/webrev
>
> There are numerous code indentation issues with some of the changed 
> code (mainly around parameter/argument lists) - but they all seem to 
> be pre-existing so I decided not to try and call them out. You did fix 
> quite a few, and I don't think you introduced any new ones. :)
>
> The main thing to look for with use of handles internal to methods is 
> whether once changed to a direct Klass/InstanceKlass*, the variable 
> becomes redundant. You picked up on a few of these but I spotted a 
> couple of others (reading the patch file the context isn't always 
> sufficient to spot these):
>
> share/vm/c1/c1_Runtime1.cpp
>
>          { Klass* klass = resolve_field_return_klass(caller_method, 
> bci, CHECK);
> -          init_klass = KlassHandle(THREAD, klass);
> +          init_klass = klass;
>
> You don't need the klass local but can assign direct to init_klass.
>
>      // convert to handle
> -    load_klass = KlassHandle(THREAD, k);
> +    load_klass = k;
>
> Comment should be deleted, plus it seems you should be able to assign 
> to load_klass directly earlier through the switch instead of 
> introducing 'k'.

This logic is not obvious and I'd rather not change it.   init_klass and 
load_klass are used further down for different purposes.  I removed the 
comment though.
>
> ---
>
> src/share/vm/jvmci/jvmciEnv.cpp
>
> 117     Klass*  kls;
>
> This local is not needed as you can assign directly to found_klass now.

Yes, that's better.
>
> ---
>
> Finally a meta-question re the changes in:
>
> src/share/vm/classfile/dictionary.hpp
>
> and the flow out from that. I'm unclear about all the changes from 
> Klass to InstanceKlass. Are all dictionary/hashtable entries 
> guaranteed to be instance classes?

Yes, they are.   This avoided multiple InstanceKlass::cast() calls.
>
> ---
>
>
>> Also, fixing InstanceKlass to not pass this_k can be done in a separate
>> cleanup.
>
> Ok.

Thank you for slogging through all of this.

Coleen
>
> Thanks,
> David
>
>> Thanks,
>> Coleen
>>
>> On 3/12/17 11:32 AM, coleen.phillimore at oracle.com wrote:
>>> Summary: Use unhandled pointers for Klass and InstanceKlass, remove
>>> handles with no implementation.
>>>
>>> These are fairly extensive changes.  The KlassHandle types have been
>>> dummy types since permgen elimination and were thought to be useful
>>> for future features.  They aren't, so can be removed (see bug for more
>>> details).   This allows stricter typing because you can use the more
>>> specific type, and using const more.  I didn't add const to these
>>> changes, because of the cascading effect.
>>>
>>> The change isn't hard to review, just tedious.  The main bug that I
>>> had was redeclaring a type inside a scope, and InstanceKlass::cast(k)
>>> can't take a NULL k, whereas instanceKlassHandle ik(THREAD, k) could.
>>>
>>> It's so nice being able to single step on gdb without going into
>>> KlassHandle constructors!
>>>
>>> open webrev at http://cr.openjdk.java.net/~coleenp/8155672.01/webrev
>>> bug link https://bugs.openjdk.java.net/browse/JDK-8155672
>>>
>>> Tested with all hotspot jtreg tests, java/lang/invoke tests,
>>> java/lang/instrument tests, all closed tonga colocated tests, and JPRT.
>>>
>>> I can continue to hold this change for a convenient time for merging
>>> purposes with other people's JDK10 changes that they've been holding,
>>> or if there are other jdk9 changes that are likely to cause a problem
>>> for merging.  I'll update the copyrights to 2017 on commit.
>>>
>>> Thanks,
>>> Coleen
>>