From a5d0c2c17482e56cae5112083207e8c0ce19cb96 Mon Sep 17 00:00:00 2001
From: Lzu Tao <taolzu@gmail.com>
Date: Mon, 13 Jul 2020 09:34:34 +0000
Subject: [PATCH 1/3] Remove redundant len binding

---
 library/std/src/sys/windows/mod.rs | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/library/std/src/sys/windows/mod.rs b/library/std/src/sys/windows/mod.rs
index 9a52371280e15..3d155a8c8f0f6 100644
--- a/library/std/src/sys/windows/mod.rs
+++ b/library/std/src/sys/windows/mod.rs
@@ -99,11 +99,10 @@ pub fn decode_error_kind(errno: i32) -> ErrorKind {
 
 pub fn unrolled_find_u16s(needle: u16, haystack: &[u16]) -> Option<usize> {
     let ptr = haystack.as_ptr();
-    let mut len = haystack.len();
     let mut start = &haystack[..];
 
     // For performance reasons unfold the loop eight times.
-    while len >= 8 {
+    while start.len() >= 8 {
         if start[0] == needle {
             return Some((start.as_ptr() as usize - ptr as usize) / 2);
         }
@@ -130,7 +129,6 @@ pub fn unrolled_find_u16s(needle: u16, haystack: &[u16]) -> Option<usize> {
         }
 
         start = &start[8..];
-        len -= 8;
     }
 
     for (i, c) in start.iter().enumerate() {

From 34c343ac27c519350577bd1bfdc4d1a3b90e6db6 Mon Sep 17 00:00:00 2001
From: Lzu Tao <taolzu@gmail.com>
Date: Mon, 13 Jul 2020 09:35:10 +0000
Subject: [PATCH 2/3] Make use of macro to avoid repetition

---
 library/std/src/sys/windows/mod.rs | 33 +++++++++---------------------
 1 file changed, 10 insertions(+), 23 deletions(-)

diff --git a/library/std/src/sys/windows/mod.rs b/library/std/src/sys/windows/mod.rs
index 3d155a8c8f0f6..ef4041e92d7dd 100644
--- a/library/std/src/sys/windows/mod.rs
+++ b/library/std/src/sys/windows/mod.rs
@@ -103,31 +103,18 @@ pub fn unrolled_find_u16s(needle: u16, haystack: &[u16]) -> Option<usize> {
 
     // For performance reasons unfold the loop eight times.
     while start.len() >= 8 {
-        if start[0] == needle {
-            return Some((start.as_ptr() as usize - ptr as usize) / 2);
-        }
-        if start[1] == needle {
-            return Some((start[1..].as_ptr() as usize - ptr as usize) / 2);
-        }
-        if start[2] == needle {
-            return Some((start[2..].as_ptr() as usize - ptr as usize) / 2);
-        }
-        if start[3] == needle {
-            return Some((start[3..].as_ptr() as usize - ptr as usize) / 2);
-        }
-        if start[4] == needle {
-            return Some((start[4..].as_ptr() as usize - ptr as usize) / 2);
-        }
-        if start[5] == needle {
-            return Some((start[5..].as_ptr() as usize - ptr as usize) / 2);
-        }
-        if start[6] == needle {
-            return Some((start[6..].as_ptr() as usize - ptr as usize) / 2);
-        }
-        if start[7] == needle {
-            return Some((start[7..].as_ptr() as usize - ptr as usize) / 2);
+        macro_rules! if_return {
+            ($($n:literal,)+) => {
+                $(
+                    if start[$n] == needle {
+                        return Some((&start[$n] as *const u16 as usize - ptr as usize) / 2);
+                    }
+                )+
+            }
         }
 
+        if_return!(0, 1, 2, 3, 4, 5, 6, 7,);
+
         start = &start[8..];
     }
 

From f55e4d036c10f5b887b4ed8c12b7b31f3bb75d23 Mon Sep 17 00:00:00 2001
From: Lzu Tao <taolzu@gmail.com>
Date: Mon, 13 Jul 2020 09:35:51 +0000
Subject: [PATCH 3/3] Get pointer from address of c directly

---
 library/std/src/sys/windows/mod.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/library/std/src/sys/windows/mod.rs b/library/std/src/sys/windows/mod.rs
index ef4041e92d7dd..982ec912c44b7 100644
--- a/library/std/src/sys/windows/mod.rs
+++ b/library/std/src/sys/windows/mod.rs
@@ -118,9 +118,9 @@ pub fn unrolled_find_u16s(needle: u16, haystack: &[u16]) -> Option<usize> {
         start = &start[8..];
     }
 
-    for (i, c) in start.iter().enumerate() {
+    for c in start {
         if *c == needle {
-            return Some((start.as_ptr() as usize - ptr as usize) / 2 + i);
+            return Some((c as *const u16 as usize - ptr as usize) / 2);
         }
     }
     None