https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71563
--- Comment #3 from Marc Glisse <glisse at gcc dot gnu.org> --- (In reply to Jakub Jelinek from comment #2) > That said, about the zero/non-zero bits, it is > even more complicated in this case, because e.g. 1 / -1 has all bits set, > the thing is just that it is then undefined behavior for the shift. > Wonder what optimization performed this at the RTL level and if it gets all > the cases right. (I didn't check) A << B is the same as A << (B & 31). If B is C << 8, it isn't hard to determine that (C << 8) & 31 is 0.
