From 747c56c2c3cc56574210bf013ac6d5863b08266c Mon Sep 17 00:00:00 2001
From: Chris Fallin <chris@cfallin.org>
Date: Thu, 6 May 2021 16:19:38 -0700
Subject: [PATCH] Some micro-optimizations in BitVec.

---
 src/bitvec.rs | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/bitvec.rs b/src/bitvec.rs
index 9260e1b..5a1c949 100644
--- a/src/bitvec.rs
+++ b/src/bitvec.rs
@@ -83,14 +83,16 @@ impl BitVec {
         let last_idx = other.bits.len() - 1;
         self.ensure_idx(last_idx);
 
-        let mut changed = false;
+        let mut changed = 0;
         for (self_word, other_word) in self.bits.iter_mut().zip(other.bits.iter()) {
-            if *other_word & !*self_word != 0 {
-                changed = true;
+            if *other_word == 0 {
+                // Avoid cache misses in `self` if `other` is zeroes.
+                continue;
             }
+            changed |= *other_word & !*self_word;
             *self_word |= *other_word;
         }
-        changed
+        changed != 0
     }
 
     pub fn and(&mut self, other: &Self) {