Segfault after printing results

[developedby]

Reproducing the behavior

Running this program with hvm run-c causes a segmentation fault after printing the results

@List/Cons = (a (b ((@List/Cons/tag (a (b c))) c)))

@List/Cons/tag = 1

@List/Nil = ((@List/Nil/tag a) a)

@List/Nil/tag = 0

@List/append = ((@List/append__C3 a) a)

@List/append__C0 = (* (c (d (a (b (* g))))))
  & @List/Cons ~ (a (f g))
  & @List/append ~ (b (e f))
  & @List/Cons ~ (c (d e))

@List/append__C1 = (?(((* (* (a a))) @List/append__C0) b) b)

@List/append__C2 = (* ({a c} ({b d} ((@List/append__C1 (a (b (e f)))) f))))
  & @List/Cons ~ (c (d e))

@List/append__C3 = (?(((a a) @List/append__C2) b) b)

@gen_lst = a
  & @gen_lst__bend0 ~ a

@gen_lst__bend0 = (a ({$([<0] ?(((* (* @List/Nil)) @gen_lst__bend0__C0) (a (b c)))) b} c))

@gen_lst__bend0__C0 = (* ($([%] $(a $([*7] $([+3] {b $([:%5] $([+3] c))})))) ({$([:-1] d) a} f)))
  & @List/Cons ~ (b (e f))
  & @gen_lst__bend0 ~ (c (d e))

@main = (* a)
  & @main2 ~ (32 a)

@main2 = (a (b d))
  & @gen_lst ~ (31 (a {b c}))
  & @quickSort ~ (c d)

@partition = a
  & @partition__fold0 ~ a

@partition__fold0 = ((@partition__fold0__C3 a) a)

@partition__fold0__C0 = (b (a (c (a d))))
  & @List/Cons ~ (b (c d))

@partition__fold0__C1 = (* (a (b (d (c d)))))
  & @List/Cons ~ (a (b c))

@partition__fold0__C2 = (* ({c d} (a ({b $([>] $(c ?((@partition__fold0__C0 @partition__fold0__C1) (d (e (f g))))))} g))))
  & @partition__fold0 ~ (a (b (e f)))

@partition__fold0__C3 = (?(((* (@List/Nil @List/Nil)) @partition__fold0__C2) a) a)

@quickSort = ((@quickSort__C1 a) a)

@quickSort__C0 = (* ({b e} (a i)))
  & @List/append ~ (d (h i))
  & @partition ~ (a (b (c f)))
  &!@quickSort ~ (c d)
  & @List/Cons ~ (e (g h))
  &!@quickSort ~ (f g)

@quickSort__C1 = (?((@List/Nil @quickSort__C0) a) a)

If we change the number on @main to be smaller than 32 this doesn't happen

System Settings

• OS: Linux (OpenSuse Tumbleweed)
• CPU: AMD Ryzen 7 5800H

Additional context

No response

[edusporto]

Minimum reproduction of the same bug in Bend:

def create(n):
  bend x = 0:
    when x < n:
      str = List/Cons { head: 1, tail: fork(x + 1) }
    else:
      str = List/Nil
  return str

def main():
  return create(37)

This is due to the fixed-size stack variable in the pretty_print_port function here.

Increasing the size of this array postpones the problem - although it increases the maximum size of the created list before segfaulting, it doesn't really solve the problem. I'm working on direct net readback through interop in Rust - that would fix the problem until the readback function in Rust overflows 😛

For now I think we could increase this array, since 256 really is quite short

[enricozb]

Just commenting here so I can refer back to it, this pretty_print_port will break even further with my planned extended numerics changes (will be using ERA as a pointer), so I'll fix this then.