Steve Howell wrote: > > The compiler doesn't know the types up front, but if > you wanted to do this kind of optimization (and you > believed that 95% of x*x cases would benefit from it, > and you're willing to sacrifice performance for the 5% > of folks that overload multiply), then the compiler > could generate bytecode that set the stage for later > conditional caching of the first execution of x*x.
True. > You'd then need the execution of the bytecodes at > runtime (ceval.c or something called by it) to work in > such a way that they only cache the result when side > effects are not an issue. At runtime you can reliably > detect whether something is still a virgin builtin, > correct? I've no idea, but I imagine that psyco knows whether or not it has a proper built-in number object when it generates specialised code for similar cases. > To my disclaimer, you would only undertake such an > optimization if multiplication were really, really > expensive (which I don't think is even true for floats > today), and even then you'd proceed cautiously. Indeed. Some believe that for "full Python" you can only introduce such measures at run-time, although extensive enough analysis of the code could perhaps suggest suitable specialisations in advance, as presumably demonstrated by Shed Skin. Paul -- http://mail.python.org/mailman/listinfo/python-list
