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rise-lang / shine

The Shine compiler for the RISE language
https://rise-lang.org
MIT License
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Slow code generation issue with code size blowup #84

Open Bastacyclop opened 3 years ago

Bastacyclop commented 3 years ago

The example expression shown in https://github.com/rise-lang/shine/pull/83 takes around 4mn to compile and generates huge code (about 60 million characters) with too many ifs.

Bastacyclop commented 3 years ago

I believe that using temporary values for index computations would avoid at least part of the exponential blowup. Additionally a lot of the branching could be eliminated at the imperative DPIA level, but this requires some work and would benefit from https://github.com/rise-lang/shine/issues/22.

Bastacyclop commented 3 years ago

If we change the program to clamp before generate, code generation is fast and the code size is reasonable (1300 characters):

      map(padClamp2D(0, 1))(input) |> fun(clamped =>
        generate(fun(i =>
          select(i < alpha)(
            zipND(2)(clamped `@` i, clamped `@` alpha) |>
              map(map(fun(p => fst(p) * snd(p))))
          )(clamped `@` alpha)
        )) |>
        map(dropLast(1)) >>
        map(map(dropLast(1))) >>
        normalize(h)(w) >> mapSeq(mapSeq(mapSeq(id)))
      )

The code size blowup might be related to how padClamp is implemented.