On Tue, Dec 22, 2020, Paolo Bonzini wrote: > On 22/12/20 19:31, David Laight wrote: > > > /* > > > * Use 2ULL to incorporate the necessary +1 in the shift; adding +1 in > > > * the shift count will overflow SHL's max shift of 63 if s=0 and e=63. > > > */ > > A comment of the desired output value would be more use. > > I think it is: > > return 'e-s' ones followed by 's' zeros without shifting by 64. > > > > What about a mix of the two: > > /* > * Return 'e-s' ones followed by 's' zeros. Note that the > * apparently obvious 1ULL << (e - s + 1) can shift by 64 if > * s=0 and e=63, which is undefined behavior. > */ Works for me, thanks!
