On Tue, Aug 20, 2024, at 03:25, Anshuman Khandual wrote: > On 8/19/24 12:43, Arnd Bergmann wrote: > > Should not the second shift operation warn about the possible > overflow scenario ? But actually it does not. Or the compiler > is too smart in detecting what's happening next in the overall > equation and do the needful while creating the mask below the > highest bit. Not sure about the reasoning behind the compiler warning for one but not the other, but I know that we rely on similar behavior in places like: #define upper_32_bits(n) ((u32)(((n) >> 16) >> 16)) which is intended to return a zero without a compiler warning when passing an 'unsigned long' input on 32-bit architectures. Arnd