RFR[s] 8179305 - Avoid repeated calls to JavaThread::last_frame in InterpreterRuntime

[Ioi Lam]

Hi Dean,

I've wrapped those 4 methods. I also added 'const' to the wrapper 
methods where possible. Here's the delta from the last posted webrev:

http://cr.openjdk.java.net/~iklam/jdk10/8179305-avoid-last-frame.v02.delta/

Thanks
- Ioi

On 5/1/17 3:58 PM, dean.long at oracle.com wrote:
>
> I was expecting you to wrap just the methods that InterpreterRuntime uses.
>
> dl
>
>
> On 5/1/17 2:18 PM, Ioi Lam wrote:
>>
>>
>> On 5/1/17 2:03 PM, dean.long at oracle.com wrote:
>>>
>>> I wasn't complaining about those, because you don't really need a 
>>> LastFrameAccessor there.  I was really talking about where you have 
>>> a LastFrameAccessor but need to escape back to frame using 
>>> get_frame() because you didn't add a new accessor method:
>>>
>>>
>>>   950       for( BasicObjectLock *kptr = last_frame.get_frame().interpreter_frame_monitor_end();
>>>   951            kptr < last_frame.get_frame().interpreter_frame_monitor_begin();
>>>   952            kptr = last_frame.get_frame().next_monitor_in_interpreter_frame(kptr) ) {
>>>
>>>  versus something like 
>>> last_frame.monitor_end()/monitor_begin()/next_monitor().
>>>
>> I could add those accessor methods, but frame has lots of methods, 
>> and I don't want to wrap each of them in case someone uses a new 
>> function in the future.
>>
>> An alternative (which I really don't like) is to override the "->" or 
>> "()" operators like the Handle class:
>>
>>     last_frame->interpreter_frame_monitor_begin();
>> or
>>     last_frame().interpreter_frame_monitor_begin();
>>
>> Thanks
>> - Ioi
>>>
>>> dl
>>>
>>>
>>> On 5/1/17 12:54 PM, Ioi Lam wrote:
>>>> Hi Dean,
>>>>
>>>> Thanks for the review. I left a few thread->last_frame() that were 
>>>> inside ifdef ASSERT, but you're right, I should change those as 
>>>> well to be consistent:
>>>>
>>>> diff -r dbee2fa1d3df src/share/vm/interpreter/interpreterRuntime.cpp
>>>> --- a/src/share/vm/interpreter/interpreterRuntime.cpp Mon May 01 
>>>> 11:16:01 2017 -0700
>>>> +++ b/src/share/vm/interpreter/interpreterRuntime.cpp Mon May 01 
>>>> 12:30:01 2017 -0700
>>>> @@ -642,7 +642,7 @@
>>>>  IRT_ENTRY_NO_ASYNC(void, 
>>>> InterpreterRuntime::monitorenter(JavaThread* thread, 
>>>> BasicObjectLock* elem))
>>>>  #ifdef ASSERT
>>>> - thread->last_frame().interpreter_frame_verify_monitor(elem);
>>>> + 
>>>> LastFrameAccessor(thread).get_frame().interpreter_frame_verify_monitor(elem);
>>>>  #endif
>>>>
>>>> @@ -659,7 +659,7 @@
>>>>  #ifdef ASSERT
>>>> - thread->last_frame().interpreter_frame_verify_monitor(elem);
>>>> + 
>>>> LastFrameAccessor(thread).get_frame().interpreter_frame_verify_monitor(elem);
>>>>  #endif
>>>>  IRT_END
>>>>
>>>> @@ -667,7 +667,7 @@
>>>>  IRT_ENTRY_NO_ASYNC(void, 
>>>> InterpreterRuntime::monitorexit(JavaThread* thread, 
>>>> BasicObjectLock* elem))
>>>>  #ifdef ASSERT
>>>> - thread->last_frame().interpreter_frame_verify_monitor(elem);
>>>> + 
>>>> LastFrameAccessor(thread).get_frame().interpreter_frame_verify_monitor(elem);
>>>>  #endif
>>>>
>>>> @@ -680,7 +680,7 @@
>>>>  #ifdef ASSERT
>>>> - thread->last_frame().interpreter_frame_verify_monitor(elem);
>>>> + 
>>>> LastFrameAccessor(thread).get_frame().interpreter_frame_verify_monitor(elem);
>>>>  #endif
>>>>  IRT_END
>>>>
>>>> What do you think?
>>>>
>>>> Thanks
>>>> - Ioi
>>>>
>>>>
>>>>
>>>> On 5/1/17 12:14 PM, dean.long at oracle.com wrote:
>>>>> Looks OK to me, but it seems arbitrary now which calls can use 
>>>>> LastFrameAccessor methods and which need to go through the 
>>>>> get_frame() back-door.
>>>>>
>>>>> dl
>>>>>
>>>>>
>>>>> On 4/28/17 4:06 AM, Ioi Lam wrote:
>>>>>> https://bugs.openjdk.java.net/browse/JDK-8179305
>>>>>> http://cr.openjdk.java.net/~iklam/jdk10/8179305-avoid-last-frame.v01/ 
>>>>>>
>>>>>>
>>>>>> Summary:
>>>>>>
>>>>>> JavaThread::last_frame() is an expensive call. We use the helper 
>>>>>> class LastFrameAccessor holds the value of last_frame:
>>>>>>
>>>>>> OLD:
>>>>>>   methodHandle m (thread, method(thread));// calls 
>>>>>> JavaThread::last_frame() internally
>>>>>>   Bytecode_loadconstant ldc(m, bci(thread));// calls 
>>>>>> JavaThread::last_frame() internally
>>>>>>
>>>>>> NEW:
>>>>>>   LastFrameAccessor last_frame(thread);
>>>>>>   methodHandle m (thread, last_frame.method());
>>>>>>   Bytecode_loadconstant ldc(m, last_frame.bci());
>>>>>>
>>>>>> Testing:
>>>>>>
>>>>>> Preliminary benchmarking shows significant VM start-up improvement:
>>>>>>
>>>>>> java -version:
>>>>>> no CDS = 80.35 ms -> 79.14ms (-1.5%)
>>>>>> w/ CDS = 53.89ms -> 52.62ms (-2.36%)
>>>>>>
>>>>>> clojure sample app:
>>>>>> no CDS = 1442.46ms -> 1436.11ms (-0.44%)
>>>>>> w/ CDS = 695.78ms -> 679.52ms (-2.34%)
>>>>>>
>>>>>> Thanks
>>>>>> - Ioi
>>>>>
>>>>
>>>
>>
>