On Wed, Jul 30, 2025 at 12:19:24PM GMT, Jakub Jelinek wrote: > On Wed, Jul 30, 2025 at 06:15:56PM +0800, Yang Yujie wrote: > > So wouldn't it be simpler if I just change the comparison in my patch into > > a memcmp? This works regardless of how comparison is implemented. > > (We all assume that expression (x) may have its address taken.) > > No. memcmp after memcpy will be always identical. > By treating the memcpy copied data as the promoted _BitInt (without knowing > anything about it) and shifting right by S (x) for unsigned it needs to do > the shift and the result will be 0 if correct and non-zero on error, > similarly for signed shifting right by S (x) - 1 the result will be 0 or -1 > if correct and otherwise erroneous. > > Jakub
I mean do the casting first: typeof(x) __y = (typeof(x)) __x; and then compare the objects of __y and (x) with memcmp.
