michaelrj-google wrote: > > Typically we don't bother to implement these unless libc starts using > > these, or needs them. Making builtins for these functions without the > > library needs them is kinda silly. > > DO we have a request for these coming from the libc maintainers? > > I think they're important for two reasons: 1) we're going to want constexpr > support for these for the same reason we want constexpr support for `strlen` > in C so defining them as recognized library builtins is the way we do that, > and 2) I think libc is going to want to have full support for bit-precise > integer types and that's easier to support from a builtin currently. That > said, CC @michaelrj-google for additional opinions
>From the libc side having these builtins would be handy for both of the >reasons Aaron mentioned. For optimization it would be helpful if the compiler >could replace the libcall with a builtin, since things like `leading_zeros` >can sometimes be reduced to a single instruction. Actually calling these bit >functions as functions is unlikely to be optimal. CC: @enh-google https://github.com/llvm/llvm-project/pull/185978 _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
