perf/many-xpts.c

   1 #include <stdlib.h>
   2
   3 #define nth_bit(x, n)   ((x >> n) & 1)
   4 #define Fn(N, Np1) \
   5    void* a##N(int x) { return ( nth_bit(x, N) ? a##Np1(x) : a##Np1(x) ); }
   6
   7 // This test allocates a lot of heap memory, and every allocation features a
   8 // different stack trace -- the stack traces are effectively a
   9 // representation of the number 'i', where each function represents a bit in
  10 // 'i', and if it's a 1 the first function is called, and if it's a 0 the
  11 // second function is called.
  12
  13 void* a999(int x)
  14 {
  15    return malloc(100);
  16 }
  17
  18 Fn(17, 999)
  19 Fn(16, 17)
  20 Fn(15, 16)
  21 Fn(14, 15)
  22 Fn(13, 14)
  23 Fn(12, 13)
  24 Fn(11, 12)
  25 Fn(10, 11)
  26 Fn( 9, 10)
  27 Fn( 8, 9)
  28 Fn( 7, 8)
  29 Fn( 6, 7)
  30 Fn( 5, 6)
  31 Fn( 4, 5)
  32 Fn( 3, 4)
  33 Fn( 2, 3)
  34 Fn( 1, 2)
  35 Fn( 0, 1)
  36
  37 int main(void)
  38 {
  39    int i;
  40
  41    // Create a large XTree.
  42    for (i = 0; i < (1 << 18); i++)
  43       a0(i);
  44
  45    // Do a lot of allocations so it gets dup'd a lot of times.
  46    for (i = 0; i < 100000; i++) {
  47       free(a1(234));
  48       free(a2(111));
  49    }
  50
  51    return 0;
  52 }