RFR: 8000780: make Zero build and run with JDK8

[Kelly O'Hair]

Looks fine. Thanks for the heads up.

-kto

On Oct 25, 2012, at 3:41 PM, Christian Thalinger wrote:

> This patch contains a Makefile change:
> 
> http://cr.openjdk.java.net/~rkennke/zerojdk8/webrev.03/make/Makefile.udiff.html
> 
> -- Chris
> 
> Begin forwarded message:
> 
>> From: Roman Kennke <rkennke at redhat.com>
>> Subject: Re: RFR: Make Zero build and run with JDK8
>> Date: October 17, 2012 4:09:13 PM PDT
>> To: Christian Thalinger <christian.thalinger at oracle.com>
>> Cc: hotspot-dev at openjdk.java.net
>> 
>> Am Mittwoch, den 17.10.2012, 15:34 -0700 schrieb Christian Thalinger:
>>> On Oct 17, 2012, at 3:05 PM, Roman Kennke <rkennke at redhat.com> wrote:
>>> 
>>>> Am Mittwoch, den 17.10.2012, 14:40 -0700 schrieb Christian Thalinger:
>>>>> On Oct 16, 2012, at 8:01 AM, Roman Kennke <rkennke at redhat.com> wrote:
>>>>> 
>>>>>> Hi Christian,
>>>>>> 
>>>>>>>>>>> In the recent weeks I worked on the Zero interpreter, to get it to build
>>>>>>>>>>> and run with JDK8, and in particular with the latest changes that came
>>>>>>>>>>> from mlvm (meth-lazy). The following webrev applies to hsx/hotspot-main:
>>>>>>>>>>> 
>>>>>>>>>>> http://cr.openjdk.java.net/~rkennke/zerojdk8/webrev.00/
>>>>>>>>> 
>>>>>>>>> src/share/vm/asm/codeBuffer.cpp:
>>>>>>>>> 
>>>>>>>>> -  if (dest->blob() == NULL) {
>>>>>>>>> +  if (dest->blob() == NULL && dest_filled != 0x0) {
>>>>>>>>> 
>>>>>>>>> Do we really need this when you have this:
>>>>>>>> 
>>>>>>>> The above is needed, because the loop above it that initializes
>>>>>>>> dest_filled is never executed. However, I will change the test to
>>>>>>>> dest_filled != NULL :-)
>>>>>>>> 
>>>>>>>>> static void pd_fill_to_bytes(void* to, size_t count, jubyte value) {
>>>>>>>>> 
>>>>>>>>> -  memset(to, value, count);
>>>>>>>>> +  if ( count > 0 ) memset(to, value, count);
>>>>>>>>> 
>>>>>>>>> }
>>>>>>>> 
>>>>>>>> Turns out that this is 1. not related to the other change above and 2.
>>>>>>>> not needed. I'll remove it.
>>>>>>>> 
>>>>>>>>> src/share/vm/interpreter/interpreter.cpp:
>>>>>>>>> 
>>>>>>>>> -  assert(_entry_table[kind] == _entry_table[abstract], "previous value must be AME entry");
>>>>>>>>> +  assert(_entry_table[kind] == NULL || _entry_table[kind] == _entry_table[abstract], "previous value must be AME entry or NULL");
>>>>>>>>> 
>>>>>>>>> Why did you need that change?
>>>>>>>> 
>>>>>>>> Apparently, before the whole table was initialized, and the methodhandle
>>>>>>>> related entries left as abstract. Now the methodhandle entries are
>>>>>>>> simply left to NULL. I suppose we could change the assert to 
>>>>>>>> 
>>>>>>>> assert(_entry_table[kind] == NULL, "previous value must be NULL");
>>>>>>>> 
>>>>>>>> Alternatively, we could fix the code that puts the other entries to also
>>>>>>>> set the methodhandle entries to AME and go back to the original assert.
>>>>>>>> What do you think?
>>>>>>> 
>>>>>>> TemplateInterpreterGenerator::generate_all sets all MH entries to AME:
>>>>>>> 
>>>>>>> // method handle entry kinds are generated later in MethodHandlesAdapterGenerator::generate:                                                                  
>>>>>>> for (int i = Interpreter::method_handle_invoke_FIRST; i <= Interpreter::method_handle_invoke_LAST; i++) {                                                      
>>>>>>> Interpreter::MethodKind kind = (Interpreter::MethodKind) i;                                                                                                  
>>>>>>> Interpreter::_entry_table[kind] = Interpreter::_entry_table[Interpreter::abstract];                                                                          
>>>>>>> }                                                                                                                                                              
>>>>>>> 
>>>>>>> You need similar code in Zero.
>>>>>> 
>>>>>> Alright, I extracted this piece of code into a separate protected method
>>>>>> void AbstractInterpreterGenerator::initializeMethodHandleEntries() and
>>>>>> call it both from templateInterpreter and cppInterpreter to initialize
>>>>>> the method handle entries to AME.
>>>>>> 
>>>>>> This new webrev also reverts this:
>>>>>> 
>>>>>>>> static void pd_fill_to_bytes(void* to, size_t count, jubyte value) {
>>>>>>>>> 
>>>>>>>>> -  memset(to, value, count);
>>>>>>>>> +  if ( count > 0 ) memset(to, value, count);
>>>>>>>>> 
>>>>>>>>> }
>>>>>>> 
>>>>>> 
>>>>>> .. and changes the 0x0 to NULL here:
>>>>>> 
>>>>>> 
>>>>>>>> src/share/vm/asm/codeBuffer.cpp:
>>>>>>>>> 
>>>>>>>>> -  if (dest->blob() == NULL) {
>>>>>>>>> +  if (dest->blob() == NULL && dest_filled != 0x0) {
>>>>>>>>> 
>>>>>>> 
>>>>>> 
>>>>>> I tried JRuby a little more and verified that it's actually using +indy,
>>>>>> and it works all well.
>>>>>> 
>>>>>> http://cr.openjdk.java.net/~rkennke/zerojdk8/webrev.01/
>>>>> 
>>>>> It seems this webrev contains the old changes.
>>>> 
>>>> Arg! I did the changes in my hotspot-comp tree then made the webrev in
>>>> my hotspot-main :-) Here's the correct one:
>>>> 
>>>> http://cr.openjdk.java.net/~rkennke/zerojdk8/webrev.02/
>>> 
>>> That looks better.  The only thing is we don't use camel-case for methods:
>>> 
>>> +  void initializeMethodHandleEntries();
>>> 
>>> Could you change it to:
>>> 
>>> +  void initialize_method_handle_entries();
>>> 
>>> I would do it myself but I cannot verify that I didn't break Zero.  I really should set up a build environment for Zero...
>> 
>> Here it comes:
>> 
>> http://cr.openjdk.java.net/~rkennke/zerojdk8/webrev.03/
>> 
>> I built both Zero and normal debug_build successfully.
>> 
>> Cheers,
>> Roman
>> 
>> 
>