From: Linus Torvalds > Sent: 17 November 2024 19:10 > > On Sun, 17 Nov 2024 at 11:05, David Laight <David.Laight@xxxxxxxxxx> wrote: > > > > I think everything can be built on a base if_const_zero(x, if_z, if_nz) > > #define const_true(x) if_const_zero(!(x), 1, 0) > > #define is_constexpr(x) if_const_zero((x) * 0, 1, 0) > > which gives a bit more flexibility. > > The is_constexpr() should probably be if_const_zero(0*!(x),1,0) to be > ok with pointers and with "long long" constants. > > And the "1,0" arguments should have a real reason for existing. I'm > not entirely convinced any other cases make much sense. I might have used them when trying to get (high >= 0u) through a -W1 build. (for example in GENMASK()). Can't quite remember the horrid solution though. Since 99% will be 1,0 maybe saving the extra expansion is best anyway. So have is_const_zero(x) and add if_const_zero(x, if_z, if_nz) later. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
