On Mon, Nov 17, 2008 at 16:04, Daniel Furrer <daniel.furrer@gmail.com> wrote:
Thanks for your answers.
On Mon, Nov 17, 2008 at 2:26 PM, Carl Friedrich Bolz <cfbolz@gmx.de> wrote:
I guess the problem for "classical" compiler optimizations applied to a compiler producing Python bytecode is that most of them are potentially unsafe. E.g. you cannot do CSE in Python, because any expression can have arbitrary side-effects. Therefore it is very limited which optimizations can be applied at all.
Well, the side-effects are a problem, so we can not do any method invocations (unless we would check that the methods are pure). Thinking about this: it's not even easily possible to optimize the subset of numerical operations because we don't have any static type information. woops...
Indeed, existing work solved this problem in the VM, by means of runtime specialization (you generate a version of the method for the commonly used argument types, so that for each specialized version you have static type information); there is a lot of literature of the late '80s and early '90s about this, mainly for Smalltalk, but also on Self. Some recommended papers on this are: * A Survey of Adaptive Optimization in Virtual Machines, Matthew Arnold, Stephen J. Find, David Grove, Michael Hind, and Peter F. Sweeney, IEEE. * An Efficient Implementation of SELF, a Dynamically-Typed Object-Oriented Language Based on Prototypes, Craig Chambers, David Ungar, and Elgin Lee, 1991 (specific discussion of code specialization, for languages such as JavaScript and Python). Regards -- Paolo Giarrusso