https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70646
mednafen at sent dot com changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |mednafen at sent dot com --- Comment #7 from mednafen at sent dot com --- Following code aborts on x86_64 4.9.2 and 5.3.0 at -O2, at least: #pragma GCC optimize("no-unit-at-a-time") typedef unsigned char u8; typedef unsigned long long u64; static inline __attribute__((always_inline)) u64 __swab64p(const u64 *p) { return (__builtin_constant_p((u64)(*p)) ? ((u64)( (((u64)(*p) & (u64)0x00000000000000ffULL) << 56) | (((u64)(*p) & (u64)0x000000000000ff00ULL) << 40) | (((u64)(*p) & (u64)0x0000000000ff0000ULL) << 24) | (((u64)(*p) & (u64)0x00000000ff000000ULL) << 8) | (((u64)(*p) & (u64)0x000000ff00000000ULL) >> 8) | (((u64)(*p) & (u64)0x0000ff0000000000ULL) >> 24) | (((u64)(*p) & (u64)0x00ff000000000000ULL) >> 40) | (((u64)(*p) & (u64)0xff00000000000000ULL) >> 56))) : __builtin_bswap64(*p)); } static inline u64 wwn_to_u64(void *wwn) { return __swab64p(wwn); } void __attribute__((noinline,noclone)) broken(u64* shost) { u8 node_name[8] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}; *shost = wwn_to_u64(node_name); } void __attribute__((noinline,noclone)) dummy(void) { __builtin_abort(); } int main(int argc, char* argv[]) { u64 v; broken(&v); if(v != (u64)-1) __builtin_abort(); return 0; }