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
