[Python-Dev] opcode dispatch optimization

Jason Orendorff jason.orendorff at gmail.com
Wed Dec 31 19:51:28 CET 2008


On Wed, Dec 31, 2008 at 11:44 AM, Christian Heimes <lists at cheimes.de> wrote:
> The patch makes use of a GCC feature where labels can be used as values:
> http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html . I didn't know
> about the feature and got confused by the unary && operator.

Right.  SpiderMonkey (Mozilla's JavaScript interpreter) does this, and
it was good for a similar win on platforms that use GCC.  (It took me
a while to figure out why it was so much faster, so I think this patch
would be better with a few very specific comments!)

SpiderMonkey calls this optimization "threaded code" too, but this
isn't the standard meaning of that term. See:
http://en.wikipedia.org/wiki/Threaded_code

-j


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