#include __thread int foo; int in_dso (int n, int *caller_foop) { int *foop; int result = 0; puts ("foo"); /* Make sure PLT is used before macros. */ asm ("" ::: "memory"); foop = &foo; if (caller_foop != NULL && foop != caller_foop) { printf ("callers address of foo differs: %p vs %p\n", caller_foop, foop); result = 1; } else if (*foop != n) { printf ("foo != %d\n", n); result = 1; } *foop = 16; return result; }