https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106343
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> --- (In reply to Andrew Pinski from comment #3) > I should note that I noticed LLVM does not handle this either. > > Basically the following operators and values can be used: > For integer: > + 0 > - 0 > * 1 > / 1 > | 0 > & -1 (all ones) > ^ 0 > > For floating point (only with -ffast-math, I think sub can be used with 0 > and add with -0.0 without but I am not 100% sure): > + 0 > - 0 > * 1 > / 1 Note for the following operators can support some constants which were there instead of a calculation (note this might be harder and maybe a different bug): op cst rhs * 0 0 | -1 -1 & 0 0
