Use memchr in libstd where possible, closes #30076

2 files changed, 4 insertions, 2 deletions

diff --git a/src/libstd/io/buffered.rs b/src/libstd/io/buffered.rs
index 90a79da3483..79eedbeda2c 100644
--- a/src/libstd/io/buffered.rs
+++ b/src/libstd/io/buffered.rs
@@ -18,6 +18,7 @@ use cmp;
 use error;
 use fmt;
 use io::{self, DEFAULT_BUF_SIZE, Error, ErrorKind, SeekFrom};
+use memchr;
 
 /// The `BufReader` struct adds buffering to any reader.
 ///
@@ -746,7 +747,7 @@ impl<W: Write> LineWriter<W> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<W: Write> Write for LineWriter<W> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        match buf.iter().rposition(|b| *b == b'\n') {
+        match memchr::memrchr(b'\n', buf) {
             Some(i) => {
                 let n = try!(self.inner.write(&buf[..i + 1]));
                 if n != i + 1 { return Ok(n) }
diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index efe40cf07c1..cc3f8097a88 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -254,6 +254,7 @@ use result;
 use string::String;
 use str;
 use vec::Vec;
+use memchr;
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::buffered::{BufReader, BufWriter, LineWriter};
@@ -1194,7 +1195,7 @@ fn read_until<R: BufRead + ?Sized>(r: &mut R, delim: u8, buf: &mut Vec<u8>)
                 Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
                 Err(e) => return Err(e)
             };
-            match available.iter().position(|x| *x == delim) {
+            match memchr::memchr(delim, available) {
                 Some(i) => {
                     buf.extend_from_slice(&available[..i + 1]);
                     (true, i + 1)