> I haven't read any papers. Having a jump table in itself isn't special
> (the compiler does exactly that when compiling the switch() statement).
> What's special is that a dedicated indirect jump instruction at the end
> of each opcode helps the CPU make a separate prediction for which opcode
> follows the other one, which is not possible with a switch statement
> where the jump instruction is shared by all opcodes. I believe that's
> where most of the speedup comes from.
> 
> If you read the patch it will probably be easy to understand.

You are right. It's easier to understand after I've learned how the
opcode_targets table is working. Previously I didn't know that one can
store the address of a label in an array. Before I got it I wondered
where the pointers were defined. Is this a special GCC feature? I
haven't seen it before.

> Don't know! Your experiments are welcome. My patch is far simpler to
> integrate though (it's small, introduces very few changes and does not
> break any existing tests).

Yes, your patch is much smaller, less intrusive and easier to understand
with a little background in CS.