[plt-scheme] Native code generation and immutable pairs

From: Noel Welsh (noelwelsh at yahoo.com)
Date: Fri Feb 10 04:40:20 EST 2006

--- Jim Blandy <jimb at red-bean.com> wrote:

> It'd be worthwhile (an assertion I have no
> data for) to do analyses that can prove that values
> appearing at certain points in the program always have 
> certain types, so that type
> checks can be omitted.  (Some of the PLT folks have
> written papers on such analyses.)

Data is here:


"Control Flow Analysis: a Functional Languages Compilation
Paradigm", Serrano, M, 1995

Using 0-cfa to infer types and hence remove type checks
cuts execution time to about 60% of unoptimised code.  This
is very interesting -- plenty of compiler papers are
written about optimisations that get you only a 5-10%

Correct statistical analysis of results has become my
personal crusade in the last few days, so I feel compelled
to point out there is no analysis of the significance of
the results presented in the paper.  Which is to say we
cannot say how 'lucky' the author would have to be to get
these results by accident (I suspect the variance in
execution time is very small, so they would probably hold,
but it is annoying to see these simple steps not taken).


Email: noelwelsh <at> yahoo <dot> com   noel <at> untyped <dot> com
AIM: noelhwelsh
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