[MLton] Re: [MLton-commit] r7212

[Matthew Fluet]

On Fri, 10 Jul 2009, Wesley Terpstra wrote:
> Added a new pass supporting elimination / combination of type conversions.
> It is able to eliminate costly conversions through LargeWord, but not
> IntInf.
> IntInf conversions tag variables before conversion which blocks the
> analysis.

Very nice commit message.  It would also be worthwhile to add a short
comment to doc/commitlog.  Also, it would be good to document the pass at
http://mlton.org/SSASimplify.

> I ran the benchmark suite three times and only 'checksum' has a
> significant
> and reproducible change:
>
>  MLton0 -- mlton -drop-pass combineConversions
>  MLton1 -- mlton
>  run time ratio
>  benchmark  MLton1
>  checksum     0.45
>  size
>  benchmark          MLton0  MLton1
>  checksum          187,726 186,254
>  compile time
>  benchmark         MLton0 MLton1
>  checksum            4.52   4.61
>  run time
>  benchmark         MLton0 MLton1
>  checksum           36.84  16.43
>
>
> ... which is not terribly surprising since it (and md5sum) are the only
> tests which make use of type conversions and md5sum is dominated by md5.

A very nice speedup, even if it is only on the one benchmark.