[Python-Dev] Why is Bytecode the way it is?

Thu Jul 8 16:21:16 CEST 2004

 >> Python's VM is currently a stack machine. There are arguments for
 >> making it a register machine, but if we want to do that, lets go the
 >> whole hog and not have some kind of half-assed hybrid.
 Paul> I'm not really talking about a register machine either. I don't
 Paul> understand why you would want to copy values from a heap in "main
 Paul> memory" into a register *still in main memory* to have the
 Paul> bytecodes operate on them to store to a register and then back to
 Paul> main memory.
When I looked at this a long time ago it I seem to recall that roughly 60%
of the opcodes executed did nothing more than copy values to or from the
stack (of course, pushes and pops are some of the more efficient opcodes in
the instruction set). A three-address machine model would reduce this data
movement substantially.
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