enh-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 > > We also should run this through our test suites to see if there is any > discrepancy, or missing tests for edge cases.
the bionic tests are here, if you're interested: https://cs.android.com/android/platform/superproject/+/android-latest-release:bionic/tests/stdbit_test.cpp https://github.com/llvm/llvm-project/pull/185978 _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
