http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60088
--- Comment #23 from Jacob Abel <thatcadguy at gmail dot com> --- If it helps at all, the following produces the same problem under gcc: #include <quadmath.h> #include <stdlib.h> int main(void) { __float128 *ptr = NULL; int i; if (ptr = malloc(100 * sizeof(__float128))) for (i = 0; i < 100; i++) ptr[i] = 0; return 0; } segfault with -march=native, fine without.