int ret;
for(ret = unw_init_local(&c, (unw_context_t *)stack_context); ret >= 0; ret = unw_step(&c)){
mc_stack_frame_t stack_frame = xbt_new(s_mc_stack_frame_t, 1);
int ret;
for(ret = unw_init_local(&c, (unw_context_t *)stack_context); ret >= 0; ret = unw_step(&c)){
mc_stack_frame_t stack_frame = xbt_new(s_mc_stack_frame_t, 1);