[libc-commits] [libc] [libc][stdbit] implement stdc_first_leading_one (C23) (PR #81502)

[via libc-commits]

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@@ -268,6 +268,11 @@ SPECIALIZE_FLZ(first_leading_zero, unsigned long long, __builtin_clzll)
 
 #undef SPECIALIZE_FLZ
 
+template <typename T, typename = cpp::enable_if_t<cpp::is_unsigned_v<T>>>
+[[nodiscard]] LIBC_INLINE constexpr int first_leading_one(T value) {
+  return !value ? 0 : countl_zero<T>(static_cast<T>(value)) + 1;
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michaelrj-google wrote:

would it be better to define `first_leading_one` as `first_leading_zero(~value)`?

https://github.com/llvm/llvm-project/pull/81502