Scott David Daniels <[EMAIL PROTECTED]> writes: > Current speeds are due to deep pipelines, and a conditional in the > INCREF code would blow a pipeline.
I think most of the time, branch prediction will prevent the cache flush. Anyway, with consed integers, there's still going to be a conditional or even a dispatch on the tag field. Finally, when you know you're dealing with small integers, you don't need to even check the tags. Some implementations use the low order bits as tags with a tag==0 meaning an integer. That means if you have two tagged integers, you can add and subtract them without having to twiddle the tags. The alternative (tag==1 means integer) means you don't have to mask off the tag bits to dereference pointers, and you can still add a constant to a tagged int by simply adjusting the constant appropriately. E.g., with one tag bit, to increment you'd add 2 to the tagged int. -- http://mail.python.org/mailman/listinfo/python-list
