extern void *malloc(__SIZE_TYPE__); extern void *memset(void *, int, __SIZE_TYPE__); typedef struct { short a; unsigned short b; unsigned short c; unsigned long long Count; long long Count2; } __attribute__((packed)) Struct1; typedef struct { short a; unsigned short b; unsigned short c; unsigned long long d; long long e; long long f; } __attribute__((packed)) Struct2; typedef union { Struct1 a; Struct2 b; } Union; typedef struct { int Count; Union List[0]; } __attribute__((packed)) Struct3; unsigned long long Sum (Struct3 *instrs) __attribute__((noinline)); unsigned long long Sum (Struct3 *instrs) { unsigned long long count = 0; int i; for (i = 0; i < instrs->Count; i++) { count += instrs->List[i].a.Count; } return count; } long long Sum2 (Struct3 *instrs) __attribute__((noinline)); long long Sum2 (Struct3 *instrs) { long long count = 0; int i; for (i = 0; i < instrs->Count; i++) { count += instrs->List[i].a.Count2; } return count; } main() { Struct3 *p = malloc (sizeof (int) + 3 * sizeof(Union)); memset(p, 0, sizeof(int) + 3*sizeof(Union)); p->Count = 3; p->List[0].a.Count = 555; p->List[1].a.Count = 999; p->List[2].a.Count = 0x101010101ULL; p->List[0].a.Count2 = 555; p->List[1].a.Count2 = 999; p->List[2].a.Count2 = 0x101010101LL; if (Sum(p) != 555 + 999 + 0x101010101ULL) abort(); if (Sum2(p) != 555 + 999 + 0x101010101LL) abort(); return 0; }