On Fri, 6 May 2022, Matthias Gehre via Gcc wrote: > We would like to add support for division/modulo on large arbitrary > precision integers to libgcc/compiler-rt as required by C23's _BitInt > type [0].
Note that each architecture also needs to specify its _BitInt ABI (including such things as whether the values of padding bits inside the size of the _BitInt type, or outside that size but within a register used for argument passing or return, have specified values or are arbitrary). HJ has a proposal for x86_64 on a branch of the ABI, but it hasn't been merged to master yet. > /// Computes the unsigned division of a / b for two large integers > /// composed of n significant words. > /// Writes the quotient to quo and the remainder to rem. > /// > /// \param quo The quotient represented by n words. Must be non-null. > /// \param rem The remainder represented by n words. Must be non-null. > /// \param a The dividend represented by n + 1 words. Must be non-null. > /// \param b The divisor represented by n words. Must be non-null. > > /// \note The word order is in host endianness. > /// \note Might modify a and b. > /// \note The storage of 'a' needs to hold n + 1 elements because some > /// implementations need extra scratch space in the most significant > word. > /// The value of that word is ignored. This proposed interface doesn't say anything about what aliasing is or isn't permitted among the four arrays pointed to. -- Joseph S. Myers jos...@codesourcery.com
