Add instrumentation in the TemplateInterpreter

[Christian Thalinger]

> On Feb 18, 2016, at 9:30 AM, Khanh Nguyen <ktruong.nguyen at gmail.com> wrote:
> 
> The main reason is the performance difference between the TemplateInterpreter and the BytecodeInterpreter in Zero.
> I did not verify the difference but I found from this mailing list that the difference is 10x.
> 
> 

But the instrumentation you are adding is quite expensive and I’m assuming this is for research or academia?

> And since we are talking about Zero. How much is the performance difference between ZeroShark and the standard Hotspot, do you by any chance know?
> 
> Thanks
> 
> On Feb 18, 2016 11:14 AM, "Christian Thalinger" <christian.thalinger at oracle.com <mailto:christian.thalinger at oracle.com>> wrote:
> Can you share the reason?
> 
>> On Feb 18, 2016, at 8:01 AM, Khanh Nguyen <ktruong.nguyen at gmail.com <mailto:ktruong.nguyen at gmail.com>> wrote:
>> 
>> Unfortunately it has to be the Template Interpreter.
>> 
>> On Feb 18, 2016 9:27 AM, "Christian Thalinger" <christian.thalinger at oracle.com <mailto:christian.thalinger at oracle.com>> wrote:
>> Does it have to be the template interpreter or could you do your work with Zero as well?
>> 
>> > On Feb 9, 2016, at 11:19 PM, Khanh Nguyen <ktruong.nguyen at gmail.com <mailto:ktruong.nguyen at gmail.com>> wrote:
>> >
>> > Hello,
>> >
>> > I want to add instrumentation to monitor all reads and writes in the
>> > TemplateInterpreter, I think I got the correct place for it in
>> > /cpu/x86/vm/templateTable_x86_64.cpp. Can someone please tell me if I'm
>> > doing it right?
>> >
>> > For writes:
>> > static void do_oop_store(InterpreterMacroAssembler* _masm,
>> >                         Address obj,
>> >                         Register val,
>> >                         BarrierSet::Name barrier,
>> >                         bool precise) {
>> > [...]
>> > case BarrierSet::CardTableModRef:
>> >  case BarrierSet::CardTableExtension:
>> >      {
>> >        if (val == noreg) {
>> >          __ store_heap_oop_null(obj);
>> >        } else {
>> >          __ store_heap_oop(obj, val);
>> >
>> > /*mycodeA*/  __ movptr(c_rarg1, obj.base()); // save this value otherwise
>> > it will be changed?
>> >
>> >          // flatten object address if needed
>> >          if (!precise || (obj.index() == noreg && obj.disp() == 0)) {
>> >            __ store_check(obj.base());
>> > /*mycodeB*/ __ call_VM(noreg, //void
>> >                       CAST_FROM_FN_PTR(address,
>> >                                        InterpreterRuntime::write_helper),
>> >                       c_rarg1,  // obj
>> >                       c_rarg1, // field address because store check is
>> > called on field address
>> >                       val);
>> >          } else {
>> >            __ leaq(rdx, obj);
>> >            __ store_check(rdx);
>> > /*mycodeC*/ __ call_VM(noreg, //void
>> >                         CAST_FROM_FN_PTR(address,
>> >                                          InterpreterRuntime::write_helper),
>> >                         c_rarg1,  // obj
>> >                         rdx, // field address, because store check is
>> > called on field address
>> >                         val);
>> >        }
>> >      }
>> >      break;
>> >
>> > For reads:
>> > case Bytecodes::_fast_agetfield:
>> >    __ load_heap_oop(rax, field);
>> >
>> > /*mycodeD*/     __ call_VM(noreg,
>> >               CAST_FROM_FN_PTR(address,
>> >                                InterpreterRuntime::read_barrier_helper),
>> >               rax);
>> >
>> > __ verify_oop(rax);
>> >    break;
>> >
>> > My questions are:
>> >
>> > 1) I thought this represents a putfield a.f=b where a.f is represented by
>> > the parameter obj of type Address. b is obvious the parameter val of type
>> > Register. Especially in obj there are fields: base, index and disp. But as
>> > I run this, looks like obj is actually the field address. (the case mycodeB)
>> > I haven't found a test case that can trigger the case mycodeC to see the
>> > behavior (i.e., rdx might get destroyed and I got random value back or
>> > c_rarg1 is the obj address and rdx is field address)
>> >
>> > 2) Before this, I tried to insert the same __ call_VM in fast_aputfield
>> > before do_oop_store but it results in JVM crash. I don't understand the
>> > reason why. What I did in the call is just print the parameters. I did see
>> > the values printed (only the 1st time it goes to the method) but then the
>> > VM crashed. I thought __ call_VM will preserve all registers's value and
>> > restore properly when comes back. My instrumentation has no side effect, I
>> > just observe and record the values (actually just printing the values to
>> > test).
>> >
>> > 3) Is it strictly required to have the line /*mycodeA*/ I tried to, in
>> > mycodeB line, pass obj.base() twice and it got build errors for "smashed
>> > args"?
>> >
>> > I greatly appreciate your time,
>> >
>> > Best,
>> >
>> > Khanh Nguyen