Message78620
> I'm having trouble understanding the technique of the jump table. Can
> you provide some links to papers that explain the threaded code? I'm
> interested in learning more.
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.
I had the idea to try this after a thread on pypy-dev, there are more
references there:
http://codespeak.net/pipermail/pypy-dev/2008q4/004916.html
> How does your implementation compare to the GForth based threaded code
> speedwise?
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). |
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Date |
User |
Action |
Args |
2008-12-31 16:15:22 | pitrou | set | recipients:
+ pitrou, lemburg, arigo, christian.heimes |
2008-12-31 16:15:21 | pitrou | link | issue4753 messages |
2008-12-31 16:15:20 | pitrou | create | |
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