I suspect that's a bug that should be able to be safely converted to a
T_OBJECT.
The code you reference in serialize.cpp is used to write out and read in
data to/from the shared class archive file for class data sharing (CDS).
It writes out a number of constants in the header of the file and then
verifies that these constants haven't changed when the archive file is
read back in. If you change this from T_BYTE to T_OBJECT, it will
likely change that value (unless we're real lucky with the alignments),
and this may prevent archive files created before your change from being
loaded into VMs after your change. I think that's ok, though, since
deployments run -Xshare:dump (creating a new archive) whenever a new JDK
is installed.
--
- Keith
Christian Thalinger wrote:
> Hi!
>
> Yesterday I wanted to add:
>
> objArrayOopDesc::base_offset_in_bytes() (note: with no argument)
>
> because an objArrayOopDesc holds only oops anyway, so always using
> T_OBJECT seems correct to me.
>
> After adding the method and doing a compile, I noticed that
> serialize.cpp:54 uses it like this:
>
> soc->do_tag(objArrayOopDesc::base_offset_in_bytes(T_BYTE));
>
> That looks very odd and, unfortunately, does not have a comment that
> explains why it is done that way. Can someone explain to me why T_BYTE
> is used in that case and if it could be changed to T_OBJECT?
>
> -- Christian
