check_cxx_source_compiles("int main() { return __builtin_bswap32(42); }" HAVE_BUILTIN_BSWAP32)

check_c_source_compiles("
    int main(void) {
      (void)__builtin_bswap32(0);
      return 0;
    }
  " HAVE_BUILTIN_BSWAP32)

check_c_source_compiles("
    int main(void) {
      (void)__builtin_bswap32(0);
      return 0;
    }
  " HAVE_BUILTIN_BSWAP32)

check_c_source_compiles(
  "
    int main(void) {
      (void)__builtin_bswap32(0);
      return 0;
    }
  "
  HAVE_BUILTIN_BSWAP32)