jsr instructions in OpenJDK 6 classes

[Jonathan Gibbons]

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.
>
> 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