static void add_segment(mstate m, char* tbase, size_t tsize, flag_t mmapped) {
/* Determine locations and sizes of segment, fenceposts, old top */
char* old_top = (char*)m->top;
static void add_segment(mstate m, char* tbase, size_t tsize, flag_t mmapped) {
/* Determine locations and sizes of segment, fenceposts, old top */
char* old_top = (char*)m->top;