[Python-Dev] Re: Memory size overflows

[Tim Peters]

[Gerald S. Williams]
> I didn't find any way to improve the actual overflow check,
> although if you entirely replace the "fast path" check with
> checks involving unsigned masking, you get some performance
> improvement. For a wide variety of input patterns, I get
> about an 18% speedup versus the core long multiply code,
> when modified as shown below:

Which platform?  Which compiler?  What was your test driver?  Was this
timing the mult code in isolation, or timing Python-level multiplies?
Claims of small speedups are notoriously platform- and test-dependent.  If
it's a mixed bag across platforms, the risk of introducing a new bug would
favor leaving things alone.  In the absence of a clear correctness proof, a
Python simulation program demonstrating correctness exhaustively in small
bases would also be helpful.

> ...
> Shall I submit a patch?

Sure, but also submit your timing harness so that people can measure the
effects cross-platform and cross-compiler.