binary-trees OCaml #5 program

(* The Computer Language Benchmarks Game
 * https://salsa.debian.org/benchmarksgame-team/benchmarksgame/
 *
 * Contributed by Troestler Christophe
 * Modified by Fabrice Le Fessant
 * *reset*
 *)

type 'a tree = Empty | Node of 'a tree * 'a tree

let rec make d =
(* if d = 0 then Empty *)
  if d = 0 then Node(Empty, Empty)
  else let d = d - 1 in Node(make d, make d)

let rec check = function Empty -> 0 | Node(l, r) -> 1 + check l + check r

let min_depth = 4
let max_depth = (let n = try int_of_string(Array.get Sys.argv 1) with _ -> 10 in
                 max (min_depth + 2) n)
let stretch_depth = max_depth + 1

let () =
  (* Gc.set { (Gc.get()) with Gc.minor_heap_size = 1024 * 1024; max_overhead = -1; }; *)
  let c = check (make stretch_depth) in
  Printf.printf "stretch tree of depth %i\t check: %i\n" stretch_depth c

let long_lived_tree = make max_depth

let rec loop_depths d =
  for i = 0 to  ((max_depth - d) / 2 + 1) - 1 do
    let d = d + i * 2 in
    let niter = 1 lsl (max_depth - d + min_depth) in
    let c = ref 0 in
      for i = 1 to niter do c := !c + check(make d) done;
      Printf.printf "%i\t trees of depth %i\t check: %i\n" niter d !c;
  done

let () =
  flush stdout;
  loop_depths min_depth;
  Printf.printf "long lived tree of depth %i\t check: %i\n"
    max_depth (check long_lived_tree)

    

NOTES:
64-bit Ubuntu quad core
The OCaml native-code compiler, version 4.10.0


Tue, 05 May 2020 21:32:44 GMT

MAKE:
mv binarytrees.ocaml-5.ocaml binarytrees.ocaml-5.ml
/opt/src/ocaml-4.10.0/bin/ocamlopt -noassert -unsafe -fPIC -nodynlink -inline 100 -O3 unix.cmxa -ccopt -march=core2 binarytrees.ocaml-5.ml -o binarytrees.ocaml-5.ocaml_run
rm binarytrees.ocaml-5.ml

2.99s to complete and log all make actions

COMMAND LINE:
./binarytrees.ocaml-5.ocaml_run 21

PROGRAM OUTPUT:
stretch tree of depth 22	 check: 8388607
2097152	 trees of depth 4	 check: 65011712
524288	 trees of depth 6	 check: 66584576
131072	 trees of depth 8	 check: 66977792
32768	 trees of depth 10	 check: 67076096
8192	 trees of depth 12	 check: 67100672
2048	 trees of depth 14	 check: 67106816
512	 trees of depth 16	 check: 67108352
128	 trees of depth 18	 check: 67108736
32	 trees of depth 20	 check: 67108832
long lived tree of depth 21	 check: 4194303