#include typedef int32_t __attribute__((vector_size(8))) v2si; int64_t s64; static inline int64_t __ev_convert_s64 (v2si a) { return (int64_t) a; } int main() { union { int64_t ll; int32_t i[2]; } endianness_test; endianness_test.ll = 1; int32_t little_endian = endianness_test.i[0]; s64 = __ev_convert_s64 ((v2si){1,0xffffffff}); if (s64 != (little_endian ? 0xffffffff00000001LL : 0x1ffffffffLL)) abort (); return 0; }