Re: AAs of struct or array

[Pelle]

On 05/27/2010 02:33 PM, bearophile wrote:

I have noticed a significant speed difference between foo1 and foo2 (D2 code):

import std.c.stdio: printf;

int foo1(int x, int y) {
     static int[int[2]] cache;
     int[2] args = [x, y];
     cache[args] = x;
     return x;
}

int foo2(int x, int y) {
     static struct Pair { int x, y; }
     static int[Pair] cache;
     Pair args = Pair(x, y);
     cache[args] = x;
     return x;
}

void main() {
     enum int N = 600;
     int tot;
     foreach (x; 1 .. N)
         foreach (y; 1 .. N)
             tot += foo2(x, y); // use foo1 or foo2 here
     printf("%d\n", tot);
}


Bye,
bearophile

On my machine, foo1 takes around 9 times longer.

Why is this?