RFR: 8000818: SA constant pool need to reference to reference map after permgen removal

[Coleen Phillmore]

On 10/17/2012 9:26 PM, Coleen Phillimore wrote:
> On 10/17/2012 5:15 PM, Yumin Qi wrote:
>> Coleen,
>>
>>   This is rewrite the byte code to its original form.  SA read 
>> core(or process) get the snap shot, which method code already rewrite 
>> in hospot. This is the reverse process to dump java classes from SA.
>>
>>   _ldc and _ldc_w are got from hotspot byte code, ie, _fast_aldc and 
>> _fast_aldc_w. Now we need to fix the constantpool index for them. The 
>> index now is in reference map, they before are in constant pool cache.

I didn't see the test hotspotcode != bytecode, which will account for 
the case that not all Bytecodes::_ldc are rewritten.
This looks good to me now.
Coleen
>
> Yes, but your code is wrong.  At lines 145 and 152 you are changing 
> the index for Bytecodes::_ldc which are _not_ rewritten to point to 
> reference array.    If you see Bytecodes::_fast_aldc these bytecode 
> indexes have been rewritten to point to the resolved references array.
>
>>
>>     for _invoke_dynamic, the code is there, I don't know how to 
>> verify if it works the way it should be.
>
> There were changes in the VM which this code doesn't have.   See 
> src/share/vm/interpreter/rewriter.cpp for the VM version, look for 
> Bytecodes::_invokehandle.
>
> Coleen
>
>>
>>   Thanks
>>   Yumin
>>
>> On 10/17/2012 10:16 AM, Coleen Phillimore wrote:
>>>
>>> Yumin,
>>>
>>> I'm confused what this file is supposed to do.   Why is this 
>>> rewriting bytecodes?   Or is it reversing bytecode rewriting?
>>>
>>> Before rewriting _ldc points to a constant pool index.  After, only 
>>> ldc bytecodes that point to string or jsr 292 oops will be rewritten 
>>> to point to the resolved_references array and the bytecode is 
>>> changed to _fast_aldc, otherwise the ldc index is left alone.   So 
>>> if it's reversing rewriting, then changing lines 145 and 152 to 
>>> _fast_aldc would make whatever this does work.
>>>
>>> It looks like jsr 292 code is not reflected in this file.   More 
>>> copying for another day unless this whole SA is rearchitected.
>>>
>>> thanks,
>>> Coleen
>>>
>>> On 10/17/2012 12:51 AM, Yumin Qi wrote:
>>>> Hi, all
>>>>
>>>>   May I have your codereview on
>>>>
>>>> http://cr.openjdk.java.net/~minqi/8000818/ 
>>>> <http://cr.openjdk.java.net/%7Eminqi/8000818/>
>>>>
>>>> 8000818: SA constant pool need to reference to reference map after 
>>>> permgen removal
>>>> Summary: After permgen removal, constant pool changed to put _ldc 
>>>> and _ldc_w (fast_ldc and fast_ldcw) index to reference map, no 
>>>> longer calculated via constant pool cache.
>>>> Also, there is a mistake in 6879063: SA should use hsdis. 
>>>> Bytes.swap should only check if the underlying platform is big 
>>>> endian  since java code follows big endian.  Revert it back to its 
>>>> orginal form, else it will fail  ClassDump.
>>>>
>>>> Reviewed-by:
>>>> Contributed-by: yumin.qi at oracle.com
>>>>
>>>>
>>>> Thanks
>>>> Yumin
>