jsr instructions in OpenJDK 6 classes

[Kelly O'Hair]

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