constexpr_log2

[folly.git] / folly / portability / Constexpr.h

diff --git a/folly/portability/Constexpr.h b/folly/portability/Constexpr.h
index 0b5c5a1a59b80ad7bcd9be3342e5bd885add6fbe..a7620918bf5519eed75eeb0c56407f3c46516018 100644 (file)
--- a/folly/portability/Constexpr.h
+++ b/folly/portability/Constexpr.h
@@ -81,6 +81,11 @@ constexpr auto constexpr_abs(T t)
   return detail::constexpr_abs_helper<T>::go(t);
 }
 
+template <typename T>
+constexpr T constexpr_log2(T t) {
+  return t == T(1) ? T(0) : T(1) + constexpr_log2(t / T(2));
+}
+
 namespace detail {
 
 template <typename Char>