2007/11/7, Asaf Yaffe <[EMAIL PROTECTED]>: > Hi Mikhail, > > You wrote: > > I like the idea of simplification which you pointed, but I think this > approach is not quite correct in general: the dead code might be in > the try block. In this case stackmap locals at the dead block should > be assignable to stackmap at the handler_pc instruction. > > In other words, if catch block accesses locals defined before the try > block and > this try block has a dead code, then stackmap for the dead code can't > have empty locals: otherwise Java6 verification would fail > > > > I am not sure I understand the problem. Assume you "nop" all instructions in > the dead block and finalize it with an "athrow". According to the Java 6 > verification rules, the only thing you need is a [][java/lang/Throwable] > StackMap. This is because (from the verification algorithm): > > 1. A nop instruction is always type safe. The nop instruction does not affect > the type state > 2. An athrow instruction is type safe iff the top of the operand stack > matches Throwable > > The verifier cannot (and will not) check the consistency of this block with > other blocks because this block in unreachable.
> It will also not check the consistency of this block with "applicable" > exception handlers because it does not perform this check for "nop" and > "athrow" instructions. That's what I missed! Could you please provide a link to the quote in the spec that nop and athrow are not checked against "applicable" exception handlers? Thanks, Mikhail > > Thanks, > Asaf > > > > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around > http://mail.yahoo.com
