From bc11e5796220a69041dc4bbf7cd7db42bbe01cb1 Mon Sep 17 00:00:00 2001
From: nicoo <nicoo@debian.org>
Date: Sun, 24 May 2020 15:41:23 +0200
Subject: [PATCH] factor::factor: Use u64::trailing_zero instead of iterated
 division

No significant performance impact (most of the time is spent elsewhere),
but an easy and satisfying fix nevertheless.
---
 src/uu/factor/src/factor.rs | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/uu/factor/src/factor.rs b/src/uu/factor/src/factor.rs
index f01cae76d..894c61c81 100644
--- a/src/uu/factor/src/factor.rs
+++ b/src/uu/factor/src/factor.rs
@@ -83,9 +83,10 @@ fn factor(mut n: u64) -> Factors {
         return factors;
     }
 
-    while n % 2 == 0 {
-        n /= 2;
-        factors.push(2);
+    let z = n.trailing_zeros();
+    if z > 0 {
+        factors.add(2, z as u8);
+        n = n >> z;
     }
 
     if n == 1 {