https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66313
--- Comment #18 from Richard Biener <rguenth at gcc dot gnu.org> --- (In reply to Dmitry Babokin from comment #16) > Here's another test case with a contrary example, where a variable gets > pulled into the braces and it also causes false positive. Transformation is: > const1 * (const2 * var1 - const3 * var2) => const1*const2*var1 - const3*var2; > > > cat f.cpp > #include <iostream> > signed char var_10 = 77; > long long int var_13 = 1547580415367384384LL; > > long foo() { > long a = -6 * > // 0xbf8a6c24aa342bc0 = -4644781160949077056 > (long(16636733186465668563ULL * var_13 ) - > // 0xd4cdd0f8c2df13cf = -3112602000603278385 > long(678280911954875019ULL * var_10)); > return a; > } > > int main () { > long a = foo (); > std::cout << a << std::endl; > return 0; > } > > > g++ -fsanitize=undefined -O0 f.cpp; ./a.out > f.cpp:6:8: runtime error: signed integer overflow: -9024801181724640896 - > 228867929910118694 cannot be represented in type 'long int' > 9193074962074792026 > > If it's unrelated issue, let me know and I'll file a separate bug for it. Yes, that's an unrelated issue -- extract_muldiv likely.