jsr instructions in OpenJDK 6 classes

[Kumar Srinivasan]

On 2/2/2012 2:29 PM, Jonathan Gibbons wrote:
> On 02/02/2012 01:29 PM, Kelly O'Hair wrote:
>> On Feb 2, 2012, at 8:59 AM, Andrew Haley wrote:
>>
>>> On 02/02/2012 04:52 PM, Joe Darcy wrote:
>>>> stackmaps are used.
>>>>
>>>> I haven't delved into the OpenJDK 6 build before writing this 
>>>> email, but
>>>> I suspect some of the classes in rt.jar are compiled with -target 
>>>> 5, but
>>>> javac in OpenJDK 6 defaults to -target 6 so you wouldn't see jsr
>>>> instructions from a stock compile.
>>> Well, I'm using the same compile command so that doesn't quite 
>>> explain it,
>>> but never mind.
>>>
>>> Why are some of the classes in rt.jar are compiled with -target 5 ?
>>> Would it hurt simply to remove that?
>>>
>>> Andrew.
>>
>> Not sure about OpenJDK6.
>>
>> But I thought ALL the classes in JDK6 were compiled with -target 5.
>>
>> As I recall the big issue was the StackMapTable attributes in -target 
>> 6 classes.
>> Many of the classfile reader/writers had issues having to re-create 
>> the StackMaptable attribute
>> and I vaguely recall some performance issues, and maybe some rt.jar 
>> size issues,
>> and maybe some pack200 issues, etc. etc.

The jdk6's jars are compiled with -target 6 AFAIK, however during the 
install
build phase, the StackMapTables (since BCP jars are never verified) were 
ripped
out using pack200, in order to reduce the distribution size. This should 
not be a factor in
the openjdk6 build.

Kumar

>>
>> It was, how do you say it..... a  'can o worms' ???:^(
>>
>> -kto
>
>
> I do think it would be worthwhile to itemize the worms in a report at 
> the end of the build.
>
> -- Jon