Review Request: Zero JNI handles fix

[Gary Benson]

Gary Benson wrote:
> Keith McGuigan wrote:
> > On 03/30/10 05:52, Christian Thalinger wrote:
> > > On Mon, 2010-03-29 at 16:24 +0100, Gary Benson wrote:
> > > > Zero will exit with an error when invoked with -Xcheck:jni.
> > > > This webrev fixes:
> > > >
> > > >   http://cr.openjdk.java.net/~gbenson/zero-jnihandles-fix/
> > > >
> > > > Note that this is actually a pretty old issue, but the fix
> > > > for it got lost from the IcedTea repositories.  There's more
> > > > information here:
> > > >
> > > >   http://icedtea.classpath.org/bugzilla/show_bug.cgi?id=323
> > > >
> > > > I don't have a bug id for this.
> > >
> > > 6939182: Zero JNI handles fix
> > >
> > > I guess the changes are good since it uses an #ifdef.  Maybe one
> > > of the runtime guys could also comment on this one.
> >
> > It would be better to put this in zero-specific code somewhere
> > instead of polluting common code with #ifdef, but if that's not
> > possible...
> >
> > Also, instead of this point-fix in jniHandles, why not fix
> > last_Java_sp() to return zero_stack()->sp() in the zero case?
> > This is not the only place last_Java_sp() is called.  Might
> > want to fix it for last_Java_pc() (and related) too.
> 
> The difficulty is that what last_Java_sp is returning in Zero is the
> Zero frame pointer, which is not the highest thing on the stack.  It
> probably isn't the best thing to #ifdef this here though, I agree.
> I'll have a think about it...

I've reworked the fix:

  http://cr.openjdk.java.net/~gbenson/zero-jnihandles-fix-2/

last_Java_sp() now returns the actual Zero stack pointer.  The frame
anchor has a new last_Java_fp field that stores the value previously
stored in last_Java_sp, in much the same way as the x86 port does.

Note that the code in frame_zero.* already stored both these values,
but with the names confusingly reversed.  I have unreversed them in
this webrev.  I have also changed the type of the frame pointer be a
ZeroFrame* -- leaving the stack pointer as an intptr_t* -- to help
ensure that everything gets the arguments in the right order.

Cheers,
Gary

-- 
http://gbenson.net/