[MLton] Benchmark question

[Matthew Fluet]

> After running the benchmarks on while using flattener, the benchmark
> script reported that about half of the benchmarks failed. All the
> benchmarks compile when I run the compiler with my flag set to true.
> Obviously there is a bug, and to help with debugging I was wondering if
> there is a way to see what errors occured during the benchmark suite.

There isn't an easy way of getting the compile errors.

One simple thing to check: note that all the .sml files in the
benchmarks/tests directory are "incomplete" in some sense.  The benchmark
program appends
  val _ = Main.doit 10
(where 10 is some number specific to each benchmark; essentially, a repeat
count so the benchmark runs long enough) to each benchmark and compiles
that program.  Without the call to Main.doit, the programs essentially do
nothing, and the first couple rounds of the SSA optimizer will usually
simplify the program down to pretty much nothing; by the time your
flattener runs, there may not be anything interesting for it to do.