On Sun, 4 Sep 2016, Bernd Edlinger wrote: > good to have as well. But this code would still be suspicious > even if (x << y) is put in parentheses, because the shift count does > not change the result of the condition, as the integer overflow is > undefined behavior, and if it does not have side effects or does > not throw something, it can even be optimized away.
It's defined in GNU C (when the shift count is nonnegative and less than the width of the type) - we document that we do not optimize on the basis of it being undefined (although ubsan will still detect it). -- Joseph S. Myers jos...@codesourcery.com
