My recommendation is that we split these into two ops: Bgotoifnil and
    Bgotoifnonnil, which use only FETCH and a positive/negative offset from the
    current pc, and Bgotoifnil2 and Bgotoifnonnil2 which use the old logic
    (FETCH2, and an absolute offset from the start of the bytecode stream).

This incompatibility might be more trouble than it is worth.

--
Dr Richard Stallman
President, Free Software Foundation
51 Franklin St
Boston MA 02110
USA
www.fsf.org  www.gnu.org
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