Very slow parser (probably exponential slow)

[XJIE6]

To show the problem, let's take undermentioned program

fun foo (p1, p2, p3) {
    return p1
}

fun f1 (p1, p2, p3) local p4, p5 {
    p4 := {};
    while (1) do
        case p2[p3[0]] of
             A (a, b) ->
                p5 := foo(p3, p2, a);
                p4 := p5 : p4;
                foo(p3, b, p5)
            |B (a, b) ->
                case P(foo(p3, p2, a), foo(p3, p2, b)) of
                     P (L (a), L (b)) -> p5 := L (a + b)
                    |P (a, b)         -> p5 := foo(p3, a, b)
                esac;
                p4 := p5 : p4;
                foo(p3, b, p5)
            |C (a, b) ->
                case P(foo(p3, p2, a), foo(p3, p2, b)) of
                     P (L (a), L (b)) -> p5 := L (a - b)
                    |P (a, b)         -> p5 := foo(p3, a, b)
                esac;
                p4 := p5 : p4;
                foo(p3, b, p5)
            |D (a) ->
                p5 := foo(p3, p2, a);
                p4 := p5 : p4;
                case p3[1][7] of
                    L (m) -> p3[1][7] := L (m + 1);
                             p3[2][m + 1] := p5
                esac
            |E -> 
                return p4
            |a -> skip
        esac
    od;
    return p4
}

write(7)

It's compilation time is about 1s. If we copy function f1 and rename it to f2, compilation time will be about 3s. Repeating this, we can get 33s for program with f3 and 50 MINUTES!!! for f4. Debugging shows that parser takes whole time

[danyaberezun]

Updated: parser is very slow and hungry on big arrays. For example, an array of 2000 zeros needs 74GB RAM and several minutes of running time. If RAM amount is not enough then time tends to infinity.