Auto merge of #61305 - Centril:rollup-t39m00m, r=Centril

Rollup of 11 pull requests

Successful merges:

 - #58975 (Implement `iter::Sum` and `iter::Product` for `Option`)
 - #60542 (Add Step::sub_usize)
 - #60555 (Implement nth_back for RChunks(Exact)(Mut))
 - #60766 (Weak::into_raw)
 - #61048 (Feature/nth back chunks)
 - #61191 (librustc_errors: Move annotation collection to own impl)
 - #61235 (Stabilize bufreader_buffer feature)
 - #61249 (Rename Place::local to Place::local_or_deref_local)
 - #61291 (Avoid unneeded bug!() call)
 - #61294 (Rename `TraitOrImpl` to `Assoc` and `trait_or_impl` to `assoc`.)
 - #61297 (Remove LLVM instruction stats and other (obsolete) codegen stats.)

Failed merges:

r? @ghost

29 files changed, 900 insertions, 503 deletions

diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs
index 0dffb19476f..1f357a719bb 100644
--- a/src/liballoc/rc.rs
+++ b/src/liballoc/rc.rs
@@ -239,7 +239,7 @@ use core::fmt;
 use core::hash::{Hash, Hasher};
 use core::intrinsics::abort;
 use core::marker::{self, Unpin, Unsize, PhantomData};
-use core::mem::{self, align_of_val, forget, size_of_val};
+use core::mem::{self, align_of, align_of_val, forget, size_of_val};
 use core::ops::{Deref, Receiver, CoerceUnsized, DispatchFromDyn};
 use core::pin::Pin;
 use core::ptr::{self, NonNull};
@@ -416,11 +416,7 @@ impl<T: ?Sized> Rc<T> {
     /// ```
     #[stable(feature = "rc_raw", since = "1.17.0")]
     pub unsafe fn from_raw(ptr: *const T) -> Self {
-        // Align the unsized value to the end of the RcBox.
-        // Because it is ?Sized, it will always be the last field in memory.
-        let align = align_of_val(&*ptr);
-        let layout = Layout::new::<RcBox<()>>();
-        let offset = (layout.size() + layout.padding_needed_for(align)) as isize;
+        let offset = data_offset(ptr);
 
         // Reverse the offset to find the original RcBox.
         let fake_ptr = ptr as *mut RcBox<T>;
@@ -1262,6 +1258,143 @@ impl<T> Weak<T> {
             ptr: NonNull::new(usize::MAX as *mut RcBox<T>).expect("MAX is not 0"),
         }
     }
+
+    /// Returns a raw pointer to the object `T` pointed to by this `Weak<T>`.
+    ///
+    /// It is up to the caller to ensure that the object is still alive when accessing it through
+    /// the pointer.
+    ///
+    /// The pointer may be [`null`] or be dangling in case the object has already been destroyed.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(weak_into_raw)]
+    ///
+    /// use std::rc::{Rc, Weak};
+    /// use std::ptr;
+    ///
+    /// let strong = Rc::new(42);
+    /// let weak = Rc::downgrade(&strong);
+    /// // Both point to the same object
+    /// assert!(ptr::eq(&*strong, Weak::as_raw(&weak)));
+    /// // The strong here keeps it alive, so we can still access the object.
+    /// assert_eq!(42, unsafe { *Weak::as_raw(&weak) });
+    ///
+    /// drop(strong);
+    /// // But not any more. We can do Weak::as_raw(&weak), but accessing the pointer would lead to
+    /// // undefined behaviour.
+    /// // assert_eq!(42, unsafe { *Weak::as_raw(&weak) });
+    /// ```
+    ///
+    /// [`null`]: ../../std/ptr/fn.null.html
+    #[unstable(feature = "weak_into_raw", issue = "60728")]
+    pub fn as_raw(this: &Self) -> *const T {
+        match this.inner() {
+            None => ptr::null(),
+            Some(inner) => {
+                let offset = data_offset_sized::<T>();
+                let ptr = inner as *const RcBox<T>;
+                // Note: while the pointer we create may already point to dropped value, the
+                // allocation still lives (it must hold the weak point as long as we are alive).
+                // Therefore, the offset is OK to do, it won't get out of the allocation.
+                let ptr = unsafe { (ptr as *const u8).offset(offset) };
+                ptr as *const T
+            }
+        }
+    }
+
+    /// Consumes the `Weak<T>` and turns it into a raw pointer.
+    ///
+    /// This converts the weak pointer into a raw pointer, preserving the original weak count. It
+    /// can be turned back into the `Weak<T>` with [`from_raw`].
+    ///
+    /// The same restrictions of accessing the target of the pointer as with
+    /// [`as_raw`] apply.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(weak_into_raw)]
+    ///
+    /// use std::rc::{Rc, Weak};
+    ///
+    /// let strong = Rc::new(42);
+    /// let weak = Rc::downgrade(&strong);
+    /// let raw = Weak::into_raw(weak);
+    ///
+    /// assert_eq!(1, Rc::weak_count(&strong));
+    /// assert_eq!(42, unsafe { *raw });
+    ///
+    /// drop(unsafe { Weak::from_raw(raw) });
+    /// assert_eq!(0, Rc::weak_count(&strong));
+    /// ```
+    ///
+    /// [`from_raw`]: struct.Weak.html#method.from_raw
+    /// [`as_raw`]: struct.Weak.html#method.as_raw
+    #[unstable(feature = "weak_into_raw", issue = "60728")]
+    pub fn into_raw(this: Self) -> *const T {
+        let result = Self::as_raw(&this);
+        mem::forget(this);
+        result
+    }
+
+    /// Converts a raw pointer previously created by [`into_raw`] back into `Weak<T>`.
+    ///
+    /// This can be used to safely get a strong reference (by calling [`upgrade`]
+    /// later) or to deallocate the weak count by dropping the `Weak<T>`.
+    ///
+    /// It takes ownership of one weak count. In case a [`null`] is passed, a dangling [`Weak`] is
+    /// returned.
+    ///
+    /// # Safety
+    ///
+    /// The pointer must represent one valid weak count. In other words, it must point to `T` which
+    /// is or *was* managed by an [`Rc`] and the weak count of that [`Rc`] must not have reached
+    /// 0. It is allowed for the strong count to be 0.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(weak_into_raw)]
+    ///
+    /// use std::rc::{Rc, Weak};
+    ///
+    /// let strong = Rc::new(42);
+    ///
+    /// let raw_1 = Weak::into_raw(Rc::downgrade(&strong));
+    /// let raw_2 = Weak::into_raw(Rc::downgrade(&strong));
+    ///
+    /// assert_eq!(2, Rc::weak_count(&strong));
+    ///
+    /// assert_eq!(42, *Weak::upgrade(&unsafe { Weak::from_raw(raw_1) }).unwrap());
+    /// assert_eq!(1, Rc::weak_count(&strong));
+    ///
+    /// drop(strong);
+    ///
+    /// // Decrement the last weak count.
+    /// assert!(Weak::upgrade(&unsafe { Weak::from_raw(raw_2) }).is_none());
+    /// ```
+    ///
+    /// [`null`]: ../../std/ptr/fn.null.html
+    /// [`into_raw`]: struct.Weak.html#method.into_raw
+    /// [`upgrade`]: struct.Weak.html#method.upgrade
+    /// [`Rc`]: struct.Rc.html
+    /// [`Weak`]: struct.Weak.html
+    #[unstable(feature = "weak_into_raw", issue = "60728")]
+    pub unsafe fn from_raw(ptr: *const T) -> Self {
+        if ptr.is_null() {
+            Self::new()
+        } else {
+            // See Rc::from_raw for details
+            let offset = data_offset(ptr);
+            let fake_ptr = ptr as *mut RcBox<T>;
+            let ptr = set_data_ptr(fake_ptr, (ptr as *mut u8).offset(-offset));
+            Weak {
+                ptr: NonNull::new(ptr).expect("Invalid pointer passed to from_raw"),
+            }
+        }
+    }
 }
 
 pub(crate) fn is_dangling<T: ?Sized>(ptr: NonNull<T>) -> bool {
@@ -2007,3 +2140,20 @@ impl<T: ?Sized> AsRef<T> for Rc<T> {
 
 #[stable(feature = "pin", since = "1.33.0")]
 impl<T: ?Sized> Unpin for Rc<T> { }
+
+unsafe fn data_offset<T: ?Sized>(ptr: *const T) -> isize {
+    // Align the unsized value to the end of the RcBox.
+    // Because it is ?Sized, it will always be the last field in memory.
+    let align = align_of_val(&*ptr);
+    let layout = Layout::new::<RcBox<()>>();
+    (layout.size() + layout.padding_needed_for(align)) as isize
+}
+
+/// Computes the offset of the data field within ArcInner.
+///
+/// Unlike [`data_offset`], this doesn't need the pointer, but it works only on `T: Sized`.
+fn data_offset_sized<T>() -> isize {
+    let align = align_of::<T>();
+    let layout = Layout::new::<RcBox<()>>();
+    (layout.size() + layout.padding_needed_for(align)) as isize
+}
diff --git a/src/liballoc/sync.rs b/src/liballoc/sync.rs
index 90c7859b3db..70865656c51 100644
--- a/src/liballoc/sync.rs
+++ b/src/liballoc/sync.rs
@@ -13,7 +13,7 @@ use core::borrow;
 use core::fmt;
 use core::cmp::{self, Ordering};
 use core::intrinsics::abort;
-use core::mem::{self, align_of_val, size_of_val};
+use core::mem::{self, align_of, align_of_val, size_of_val};
 use core::ops::{Deref, Receiver, CoerceUnsized, DispatchFromDyn};
 use core::pin::Pin;
 use core::ptr::{self, NonNull};
@@ -397,11 +397,7 @@ impl<T: ?Sized> Arc<T> {
     /// ```
     #[stable(feature = "rc_raw", since = "1.17.0")]
     pub unsafe fn from_raw(ptr: *const T) -> Self {
-        // Align the unsized value to the end of the ArcInner.
-        // Because it is ?Sized, it will always be the last field in memory.
-        let align = align_of_val(&*ptr);
-        let layout = Layout::new::<ArcInner<()>>();
-        let offset = (layout.size() + layout.padding_needed_for(align)) as isize;
+        let offset = data_offset(ptr);
 
         // Reverse the offset to find the original ArcInner.
         let fake_ptr = ptr as *mut ArcInner<T>;
@@ -1071,6 +1067,144 @@ impl<T> Weak<T> {
             ptr: NonNull::new(usize::MAX as *mut ArcInner<T>).expect("MAX is not 0"),
         }
     }
+
+    /// Returns a raw pointer to the object `T` pointed to by this `Weak<T>`.
+    ///
+    /// It is up to the caller to ensure that the object is still alive when accessing it through
+    /// the pointer.
+    ///
+    /// The pointer may be [`null`] or be dangling in case the object has already been destroyed.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(weak_into_raw)]
+    ///
+    /// use std::sync::{Arc, Weak};
+    /// use std::ptr;
+    ///
+    /// let strong = Arc::new(42);
+    /// let weak = Arc::downgrade(&strong);
+    /// // Both point to the same object
+    /// assert!(ptr::eq(&*strong, Weak::as_raw(&weak)));
+    /// // The strong here keeps it alive, so we can still access the object.
+    /// assert_eq!(42, unsafe { *Weak::as_raw(&weak) });
+    ///
+    /// drop(strong);
+    /// // But not any more. We can do Weak::as_raw(&weak), but accessing the pointer would lead to
+    /// // undefined behaviour.
+    /// // assert_eq!(42, unsafe { *Weak::as_raw(&weak) });
+    /// ```
+    ///
+    /// [`null`]: ../../std/ptr/fn.null.html
+    #[unstable(feature = "weak_into_raw", issue = "60728")]
+    pub fn as_raw(this: &Self) -> *const T {
+        match this.inner() {
+            None => ptr::null(),
+            Some(inner) => {
+                let offset = data_offset_sized::<T>();
+                let ptr = inner as *const ArcInner<T>;
+                // Note: while the pointer we create may already point to dropped value, the
+                // allocation still lives (it must hold the weak point as long as we are alive).
+                // Therefore, the offset is OK to do, it won't get out of the allocation.
+                let ptr = unsafe { (ptr as *const u8).offset(offset) };
+                ptr as *const T
+            }
+        }
+    }
+
+    /// Consumes the `Weak<T>` and turns it into a raw pointer.
+    ///
+    /// This converts the weak pointer into a raw pointer, preserving the original weak count. It
+    /// can be turned back into the `Weak<T>` with [`from_raw`].
+    ///
+    /// The same restrictions of accessing the target of the pointer as with
+    /// [`as_raw`] apply.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(weak_into_raw)]
+    ///
+    /// use std::sync::{Arc, Weak};
+    ///
+    /// let strong = Arc::new(42);
+    /// let weak = Arc::downgrade(&strong);
+    /// let raw = Weak::into_raw(weak);
+    ///
+    /// assert_eq!(1, Arc::weak_count(&strong));
+    /// assert_eq!(42, unsafe { *raw });
+    ///
+    /// drop(unsafe { Weak::from_raw(raw) });
+    /// assert_eq!(0, Arc::weak_count(&strong));
+    /// ```
+    ///
+    /// [`from_raw`]: struct.Weak.html#method.from_raw
+    /// [`as_raw`]: struct.Weak.html#method.as_raw
+    #[unstable(feature = "weak_into_raw", issue = "60728")]
+    pub fn into_raw(this: Self) -> *const T {
+        let result = Self::as_raw(&this);
+        mem::forget(this);
+        result
+    }
+
+    /// Converts a raw pointer previously created by [`into_raw`] back into
+    /// `Weak<T>`.
+    ///
+    /// This can be used to safely get a strong reference (by calling [`upgrade`]
+    /// later) or to deallocate the weak count by dropping the `Weak<T>`.
+    ///
+    /// It takes ownership of one weak count. In case a [`null`] is passed, a dangling [`Weak`] is
+    /// returned.
+    ///
+    /// # Safety
+    ///
+    /// The pointer must represent one valid weak count. In other words, it must point to `T` which
+    /// is or *was* managed by an [`Arc`] and the weak count of that [`Arc`] must not have reached
+    /// 0. It is allowed for the strong count to be 0.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(weak_into_raw)]
+    ///
+    /// use std::sync::{Arc, Weak};
+    ///
+    /// let strong = Arc::new(42);
+    ///
+    /// let raw_1 = Weak::into_raw(Arc::downgrade(&strong));
+    /// let raw_2 = Weak::into_raw(Arc::downgrade(&strong));
+    ///
+    /// assert_eq!(2, Arc::weak_count(&strong));
+    ///
+    /// assert_eq!(42, *Weak::upgrade(&unsafe { Weak::from_raw(raw_1) }).unwrap());
+    /// assert_eq!(1, Arc::weak_count(&strong));
+    ///
+    /// drop(strong);
+    ///
+    /// // Decrement the last weak count.
+    /// assert!(Weak::upgrade(&unsafe { Weak::from_raw(raw_2) }).is_none());
+    /// ```
+    ///
+    /// [`null`]: ../../std/ptr/fn.null.html
+    /// [`into_raw`]: struct.Weak.html#method.into_raw
+    /// [`upgrade`]: struct.Weak.html#method.upgrade
+    /// [`Weak`]: struct.Weak.html
+    /// [`Arc`]: struct.Arc.html
+    #[unstable(feature = "weak_into_raw", issue = "60728")]
+    pub unsafe fn from_raw(ptr: *const T) -> Self {
+        if ptr.is_null() {
+            Self::new()
+        } else {
+            // See Arc::from_raw for details
+            let offset = data_offset(ptr);
+            let fake_ptr = ptr as *mut ArcInner<T>;
+            let ptr = set_data_ptr(fake_ptr, (ptr as *mut u8).offset(-offset));
+            Weak {
+                ptr: NonNull::new(ptr).expect("Invalid pointer passed to from_raw"),
+            }
+        }
+    }
 }
 
 impl<T: ?Sized> Weak<T> {
@@ -2150,3 +2284,21 @@ impl<T: ?Sized> AsRef<T> for Arc<T> {
 
 #[stable(feature = "pin", since = "1.33.0")]
 impl<T: ?Sized> Unpin for Arc<T> { }
+
+/// Computes the offset of the data field within ArcInner.
+unsafe fn data_offset<T: ?Sized>(ptr: *const T) -> isize {
+    // Align the unsized value to the end of the ArcInner.
+    // Because it is ?Sized, it will always be the last field in memory.
+    let align = align_of_val(&*ptr);
+    let layout = Layout::new::<ArcInner<()>>();
+    (layout.size() + layout.padding_needed_for(align)) as isize
+}
+
+/// Computes the offset of the data field within ArcInner.
+///
+/// Unlike [`data_offset`], this doesn't need the pointer, but it works only on `T: Sized`.
+fn data_offset_sized<T>() -> isize {
+    let align = align_of::<T>();
+    let layout = Layout::new::<ArcInner<()>>();
+    (layout.size() + layout.padding_needed_for(align)) as isize
+}
diff --git a/src/libcore/iter/range.rs b/src/libcore/iter/range.rs
index f8a975cc8d4..6bbf776fb8f 100644
--- a/src/libcore/iter/range.rs
+++ b/src/libcore/iter/range.rs
@@ -34,6 +34,13 @@ pub trait Step: Clone + PartialOrd + Sized {
 
     /// Adds a `usize`, returning `None` on overflow.
     fn add_usize(&self, n: usize) -> Option<Self>;
+
+    /// Subtracts a `usize`, returning `None` on underflow.
+    fn sub_usize(&self, n: usize) -> Option<Self> {
+        // this default implementation makes the addition of `sub_usize` a non-breaking change
+        let _ = n;
+        unimplemented!()
+    }
 }
 
 // These are still macro-generated because the integer literals resolve to different types.
@@ -85,6 +92,15 @@ macro_rules! step_impl_unsigned {
                 }
             }
 
+            #[inline]
+            #[allow(unreachable_patterns)]
+            fn sub_usize(&self, n: usize) -> Option<Self> {
+                match <$t>::try_from(n) {
+                    Ok(n_as_t) => self.checked_sub(n_as_t),
+                    Err(_) => None,
+                }
+            }
+
             step_identical_methods!();
         }
     )*)
@@ -125,6 +141,25 @@ macro_rules! step_impl_signed {
                 }
             }
 
+            #[inline]
+            #[allow(unreachable_patterns)]
+            fn sub_usize(&self, n: usize) -> Option<Self> {
+                match <$unsigned>::try_from(n) {
+                    Ok(n_as_unsigned) => {
+                        // Wrapping in unsigned space handles cases like
+                        // `80_i8.sub_usize(200) == Some(-120_i8)`,
+                        // even though 200_usize is out of range for i8.
+                        let wrapped = (*self as $unsigned).wrapping_sub(n_as_unsigned) as $t;
+                        if wrapped <= *self {
+                            Some(wrapped)
+                        } else {
+                            None  // Subtraction underflowed
+                        }
+                    }
+                    Err(_) => None,
+                }
+            }
+
             step_identical_methods!();
         }
     )*)
diff --git a/src/libcore/iter/traits/accum.rs b/src/libcore/iter/traits/accum.rs
index 7815fe9c59d..4eac5cbc8e6 100644
--- a/src/libcore/iter/traits/accum.rs
+++ b/src/libcore/iter/traits/accum.rs
@@ -223,3 +223,113 @@ impl<T, U, E> Product<Result<U, E>> for Result<T, E>
         ResultShunt::process(iter, |i| i.product())
     }
 }
+
+/// An iterator adapter that produces output as long as the underlying
+/// iterator produces `Option::Some` values.
+struct OptionShunt<I> {
+    iter: I,
+    exited_early: bool,
+}
+
+impl<I, T> OptionShunt<I>
+where
+    I: Iterator<Item = Option<T>>,
+{
+    /// Process the given iterator as if it yielded a `T` instead of a
+    /// `Option<T>`. Any `None` value will stop the inner iterator and
+    /// the overall result will be a `None`.
+    pub fn process<F, U>(iter: I, mut f: F) -> Option<U>
+    where
+        F: FnMut(&mut Self) -> U,
+    {
+        let mut shunt = OptionShunt::new(iter);
+        let value = f(shunt.by_ref());
+        shunt.reconstruct(value)
+    }
+
+    fn new(iter: I) -> Self {
+        OptionShunt {
+            iter,
+            exited_early: false,
+        }
+    }
+
+    /// Consume the adapter and rebuild a `Option` value.
+    fn reconstruct<U>(self, val: U) -> Option<U> {
+        if self.exited_early {
+            None
+        } else {
+            Some(val)
+        }
+    }
+}
+
+impl<I, T> Iterator for OptionShunt<I>
+where
+    I: Iterator<Item = Option<T>>,
+{
+    type Item = T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match self.iter.next() {
+            Some(Some(v)) => Some(v),
+            Some(None) => {
+                self.exited_early = true;
+                None
+            }
+            None => None,
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        if self.exited_early {
+            (0, Some(0))
+        } else {
+            let (_, upper) = self.iter.size_hint();
+            (0, upper)
+        }
+    }
+}
+
+#[stable(feature = "iter_arith_traits_option", since = "1.37.0")]
+impl<T, U> Sum<Option<U>> for Option<T>
+where
+    T: Sum<U>,
+{
+    /// Takes each element in the `Iterator`: if it is a `None`, no further
+    /// elements are taken, and the `None` is returned. Should no `None` occur,
+    /// the sum of all elements is returned.
+    ///
+    /// # Examples
+    ///
+    /// This sums up the position of the character 'a' in a vector of strings,
+    /// if a word did not have the character 'a' the operation returns `None`:
+    ///
+    /// ```
+    /// let words = vec!["have", "a", "great", "day"];
+    /// let total: Option<usize> = words.iter().map(|w| w.find('a')).sum();
+    /// assert_eq!(total, Some(5));
+    /// ```
+    fn sum<I>(iter: I) -> Option<T>
+    where
+        I: Iterator<Item = Option<U>>,
+    {
+        OptionShunt::process(iter, |i| i.sum())
+    }
+}
+
+#[stable(feature = "iter_arith_traits_option", since = "1.37.0")]
+impl<T, U> Product<Option<U>> for Option<T>
+where
+    T: Product<U>,
+{
+    /// Takes each element in the `Iterator`: if it is a `None`, no further
+    /// elements are taken, and the `None` is returned. Should no `None` occur,
+    /// the product of all elements is returned.
+    fn product<I>(iter: I) -> Option<T>
+    where
+        I: Iterator<Item = Option<U>>,
+    {
+        OptionShunt::process(iter, |i| i.product())
+    }
+}
diff --git a/src/libcore/slice/mod.rs b/src/libcore/slice/mod.rs
index 50d2ba0d3ef..0e782bef39d 100644
--- a/src/libcore/slice/mod.rs
+++ b/src/libcore/slice/mod.rs
@@ -4158,6 +4158,24 @@ impl<'a, T> DoubleEndedIterator for Chunks<'a, T> {
             Some(snd)
         }
     }
+
+    #[inline]
+    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
+        let len = self.len();
+        if n >= len {
+            self.v = &[];
+            None
+        } else {
+            let start = (len - 1 - n) * self.chunk_size;
+            let end = match start.checked_add(self.chunk_size) {
+                Some(res) => cmp::min(res, self.v.len()),
+                None => self.v.len(),
+            };
+            let nth_back = &self.v[start..end];
+            self.v = &self.v[..start];
+            Some(nth_back)
+        }
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -4649,6 +4667,23 @@ impl<'a, T> DoubleEndedIterator for RChunks<'a, T> {
             Some(fst)
         }
     }
+
+    #[inline]
+    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
+        let len = self.len();
+        if n >= len {
+            self.v = &[];
+            None
+        } else {
+            // can't underflow because `n < len`
+            let offset_from_end = (len - 1 - n) * self.chunk_size;
+            let end = self.v.len() - offset_from_end;
+            let start = end.saturating_sub(self.chunk_size);
+            let nth_back = &self.v[start..end];
+            self.v = &self.v[end..];
+            Some(nth_back)
+        }
+    }
 }
 
 #[stable(feature = "rchunks", since = "1.31.0")]
@@ -4774,6 +4809,24 @@ impl<'a, T> DoubleEndedIterator for RChunksMut<'a, T> {
             Some(head)
         }
     }
+
+    #[inline]
+    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
+        let len = self.len();
+        if n >= len {
+            self.v = &mut [];
+            None
+        } else {
+            // can't underflow because `n < len`
+            let offset_from_end = (len - 1 - n) * self.chunk_size;
+            let end = self.v.len() - offset_from_end;
+            let start = end.saturating_sub(self.chunk_size);
+            let (tmp, tail) = mem::replace(&mut self.v, &mut []).split_at_mut(end);
+            let (_, nth_back) = tmp.split_at_mut(start);
+            self.v = tail;
+            Some(nth_back)
+        }
+    }
 }
 
 #[stable(feature = "rchunks", since = "1.31.0")]
@@ -4898,6 +4951,24 @@ impl<'a, T> DoubleEndedIterator for RChunksExact<'a, T> {
             Some(fst)
         }
     }
+
+    #[inline]
+    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
+        let len = self.len();
+        if n >= len {
+            self.v = &[];
+            None
+        } else {
+            // now that we know that `n` corresponds to a chunk,
+            // none of these operations can underflow/overflow
+            let offset = (len - n) * self.chunk_size;
+            let start = self.v.len() - offset;
+            let end = start + self.chunk_size;
+            let nth_back = &self.v[start..end];
+            self.v = &self.v[end..];
+            Some(nth_back)
+        }
+    }
 }
 
 #[stable(feature = "rchunks", since = "1.31.0")]
@@ -5016,6 +5087,25 @@ impl<'a, T> DoubleEndedIterator for RChunksExactMut<'a, T> {
             Some(head)
         }
     }
+
+    #[inline]
+    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
+        let len = self.len();
+        if n >= len {
+            self.v = &mut [];
+            None
+        } else {
+            // now that we know that `n` corresponds to a chunk,
+            // none of these operations can underflow/overflow
+            let offset = (len - n) * self.chunk_size;
+            let start = self.v.len() - offset;
+            let end = start + self.chunk_size;
+            let (tmp, tail) = mem::replace(&mut self.v, &mut []).split_at_mut(end);
+            let (_, nth_back) = tmp.split_at_mut(start);
+            self.v = tail;
+            Some(nth_back)
+        }
+    }
 }
 
 #[stable(feature = "rchunks", since = "1.31.0")]
diff --git a/src/libcore/tests/iter.rs b/src/libcore/tests/iter.rs
index 7dfb1adad9e..bedb9e75612 100644
--- a/src/libcore/tests/iter.rs
+++ b/src/libcore/tests/iter.rs
@@ -1085,6 +1085,14 @@ fn test_iterator_sum_result() {
 }
 
 #[test]
+fn test_iterator_sum_option() {
+    let v: &[Option<i32>] = &[Some(1), Some(2), Some(3), Some(4)];
+    assert_eq!(v.iter().cloned().sum::<Option<i32>>(), Some(10));
+    let v: &[Option<i32>] = &[Some(1), None, Some(3), Some(4)];
+    assert_eq!(v.iter().cloned().sum::<Option<i32>>(), None);
+}
+
+#[test]
 fn test_iterator_product() {
     let v: &[i32] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
     assert_eq!(v[..4].iter().cloned().product::<i32>(), 0);
@@ -1127,6 +1135,14 @@ impl Ord for Mod3 {
 }
 
 #[test]
+fn test_iterator_product_option() {
+    let v: &[Option<i32>] = &[Some(1), Some(2), Some(3), Some(4)];
+    assert_eq!(v.iter().cloned().product::<Option<i32>>(), Some(24));
+    let v: &[Option<i32>] = &[Some(1), None, Some(3), Some(4)];
+    assert_eq!(v.iter().cloned().product::<Option<i32>>(), None);
+}
+
+#[test]
 fn test_iterator_max() {
     let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
     assert_eq!(v[..4].iter().cloned().max(), Some(3));
diff --git a/src/libcore/tests/slice.rs b/src/libcore/tests/slice.rs
index acf6b03791f..9710f019f4e 100644
--- a/src/libcore/tests/slice.rs
+++ b/src/libcore/tests/slice.rs
@@ -135,6 +135,30 @@ fn test_chunks_nth() {
 }
 
 #[test]
+fn test_chunks_nth_back() {
+    let v: &[i32] = &[0, 1, 2, 3, 4, 5];
+    let mut c = v.chunks(2);
+    assert_eq!(c.nth_back(1).unwrap(), &[2, 3]);
+    assert_eq!(c.next().unwrap(), &[0, 1]);
+    assert_eq!(c.next(), None);
+
+    let v2: &[i32] = &[0, 1, 2, 3, 4];
+    let mut c2 = v2.chunks(3);
+    assert_eq!(c2.nth_back(1).unwrap(), &[0, 1, 2]);
+    assert_eq!(c2.next(), None);
+    assert_eq!(c2.next_back(), None);
+
+    let v3: &[i32] = &[0, 1, 2, 3, 4];
+    let mut c3 = v3.chunks(10);
+    assert_eq!(c3.nth_back(0).unwrap(), &[0, 1, 2, 3, 4]);
+    assert_eq!(c3.next(), None);
+
+    let v4: &[i32] = &[0, 1, 2];
+    let mut c4 = v4.chunks(10);
+    assert_eq!(c4.nth_back(1_000_000_000usize), None);
+}
+
+#[test]
 fn test_chunks_last() {
     let v: &[i32] = &[0, 1, 2, 3, 4, 5];
     let c = v.chunks(2);
@@ -357,6 +381,19 @@ fn test_rchunks_nth() {
 }
 
 #[test]
+fn test_rchunks_nth_back() {
+    let v: &[i32] = &[0, 1, 2, 3, 4, 5];
+    let mut c = v.rchunks(2);
+    assert_eq!(c.nth_back(1).unwrap(), &[2, 3]);
+    assert_eq!(c.next_back().unwrap(), &[4, 5]);
+
+    let v2: &[i32] = &[0, 1, 2, 3, 4];
+    let mut c2 = v2.rchunks(3);
+    assert_eq!(c2.nth_back(1).unwrap(), &[2, 3, 4]);
+    assert_eq!(c2.next_back(), None);
+}
+
+#[test]
 fn test_rchunks_last() {
     let v: &[i32] = &[0, 1, 2, 3, 4, 5];
     let c = v.rchunks(2);
@@ -408,6 +445,19 @@ fn test_rchunks_mut_nth() {
 }
 
 #[test]
+fn test_rchunks_mut_nth_back() {
+    let v: &mut [i32] = &mut [0, 1, 2, 3, 4, 5];
+    let mut c = v.rchunks_mut(2);
+    assert_eq!(c.nth_back(1).unwrap(), &[2, 3]);
+    assert_eq!(c.next_back().unwrap(), &[4, 5]);
+
+    let v2: &mut [i32] = &mut [0, 1, 2, 3, 4];
+    let mut c2 = v2.rchunks_mut(3);
+    assert_eq!(c2.nth_back(1).unwrap(), &[2, 3, 4]);
+    assert_eq!(c2.next_back(), None);
+}
+
+#[test]
 fn test_rchunks_mut_last() {
     let v: &mut [i32] = &mut [0, 1, 2, 3, 4, 5];
     let c = v.rchunks_mut(2);
@@ -461,6 +511,19 @@ fn test_rchunks_exact_nth() {
 }
 
 #[test]
+fn test_rchunks_exact_nth_back() {
+    let v: &[i32] = &[0, 1, 2, 3, 4, 5];
+    let mut c = v.rchunks_exact(2);
+    assert_eq!(c.nth_back(1).unwrap(), &[2, 3]);
+    assert_eq!(c.next_back().unwrap(), &[4, 5]);
+
+    let v2: &[i32] = &[0, 1, 2, 3, 4, 5, 6];
+    let mut c2 = v2.rchunks_exact(3);
+    assert_eq!(c2.nth_back(1).unwrap(), &[4, 5, 6]);
+    assert_eq!(c2.next(), None);
+}
+
+#[test]
 fn test_rchunks_exact_last() {
     let v: &[i32] = &[0, 1, 2, 3, 4, 5];
     let c = v.rchunks_exact(2);
@@ -519,6 +582,19 @@ fn test_rchunks_exact_mut_nth() {
 }
 
 #[test]
+fn test_rchunks_exact_mut_nth_back() {
+    let v: &mut [i32] = &mut [0, 1, 2, 3, 4, 5];
+    let mut c = v.rchunks_exact_mut(2);
+    assert_eq!(c.nth_back(1).unwrap(), &[2, 3]);
+    assert_eq!(c.next_back().unwrap(), &[4, 5]);
+
+    let v2: &mut [i32] = &mut [0, 1, 2, 3, 4, 5, 6];
+    let mut c2 = v2.rchunks_exact_mut(3);
+    assert_eq!(c2.nth_back(1).unwrap(), &[4, 5, 6]);
+    assert_eq!(c2.next(), None);
+}
+
+#[test]
 fn test_rchunks_exact_mut_last() {
     let v: &mut [i32] = &mut [0, 1, 2, 3, 4, 5];
     let c = v.rchunks_exact_mut(2);
diff --git a/src/librustc/mir/mod.rs b/src/librustc/mir/mod.rs
index a703a396b02..d4ef134728e 100644
--- a/src/librustc/mir/mod.rs
+++ b/src/librustc/mir/mod.rs
@@ -2037,7 +2037,7 @@ impl<'tcx> Place<'tcx> {
     /// a single deref of a local.
     //
     // FIXME: can we safely swap the semantics of `fn base_local` below in here instead?
-    pub fn local(&self) -> Option<Local> {
+    pub fn local_or_deref_local(&self) -> Option<Local> {
         match self {
             Place::Base(PlaceBase::Local(local)) |
             Place::Projection(box Projection {
diff --git a/src/librustc/mir/mono.rs b/src/librustc/mir/mono.rs
index a26468b0fb6..ca79bc15358 100644
--- a/src/librustc/mir/mono.rs
+++ b/src/librustc/mir/mono.rs
@@ -188,49 +188,6 @@ impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for CodegenUnit<'tcx> {
     }
 }
 
-#[derive(Clone, Default)]
-pub struct Stats {
-    pub n_glues_created: usize,
-    pub n_null_glues: usize,
-    pub n_real_glues: usize,
-    pub n_fns: usize,
-    pub n_inlines: usize,
-    pub n_closures: usize,
-    pub n_llvm_insns: usize,
-    pub llvm_insns: FxHashMap<String, usize>,
-    // (ident, llvm-instructions)
-    pub fn_stats: Vec<(String, usize)>,
-}
-
-impl_stable_hash_for!(struct self::Stats {
-    n_glues_created,
-    n_null_glues,
-    n_real_glues,
-    n_fns,
-    n_inlines,
-    n_closures,
-    n_llvm_insns,
-    llvm_insns,
-    fn_stats
-});
-
-impl Stats {
-    pub fn extend(&mut self, stats: Stats) {
-        self.n_glues_created += stats.n_glues_created;
-        self.n_null_glues += stats.n_null_glues;
-        self.n_real_glues += stats.n_real_glues;
-        self.n_fns += stats.n_fns;
-        self.n_inlines += stats.n_inlines;
-        self.n_closures += stats.n_closures;
-        self.n_llvm_insns += stats.n_llvm_insns;
-
-        for (k, v) in stats.llvm_insns {
-            *self.llvm_insns.entry(k).or_insert(0) += v;
-        }
-        self.fn_stats.extend(stats.fn_stats);
-    }
-}
-
 pub struct CodegenUnitNameBuilder<'a, 'gcx: 'tcx, 'tcx: 'a> {
     tcx: TyCtxt<'a, 'gcx, 'tcx>,
     cache: FxHashMap<CrateNum, String>,
diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index f4ee39d6988..300d0cbfba5 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -1216,21 +1216,12 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         "measure time of each rustc pass"),
     time: bool = (false, parse_bool, [UNTRACKED],
         "measure time of rustc processes"),
-    count_llvm_insns: bool = (false, parse_bool,
-        [UNTRACKED_WITH_WARNING(true,
-        "The output generated by `-Z count_llvm_insns` might not be reliable \
-         when used with incremental compilation")],
-        "count where LLVM instrs originate"),
     time_llvm_passes: bool = (false, parse_bool, [UNTRACKED_WITH_WARNING(true,
         "The output of `-Z time-llvm-passes` will only reflect timings of \
          re-codegened modules when used with incremental compilation" )],
         "measure time of each LLVM pass"),
     input_stats: bool = (false, parse_bool, [UNTRACKED],
         "gather statistics about the input"),
-    codegen_stats: bool = (false, parse_bool, [UNTRACKED_WITH_WARNING(true,
-        "The output of `-Z codegen-stats` might not be accurate when incremental \
-         compilation is enabled")],
-        "gather codegen statistics"),
     asm_comments: bool = (false, parse_bool, [TRACKED],
         "generate comments into the assembly (may change behavior)"),
     verify_llvm_ir: bool = (false, parse_bool, [TRACKED],
@@ -3259,14 +3250,10 @@ mod tests {
         assert_eq!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
         opts.debugging_opts.time_passes = true;
         assert_eq!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
-        opts.debugging_opts.count_llvm_insns = true;
-        assert_eq!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
         opts.debugging_opts.time_llvm_passes = true;
         assert_eq!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
         opts.debugging_opts.input_stats = true;
         assert_eq!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
-        opts.debugging_opts.codegen_stats = true;
-        assert_eq!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
         opts.debugging_opts.borrowck_stats = true;
         assert_eq!(reference.dep_tracking_hash(), opts.dep_tracking_hash());
         opts.debugging_opts.meta_stats = true;
diff --git a/src/librustc/session/mod.rs b/src/librustc/session/mod.rs
index 974a5bb70e6..2726a4770c8 100644
--- a/src/librustc/session/mod.rs
+++ b/src/librustc/session/mod.rs
@@ -519,15 +519,9 @@ impl Session {
     pub fn instrument_mcount(&self) -> bool {
         self.opts.debugging_opts.instrument_mcount
     }
-    pub fn count_llvm_insns(&self) -> bool {
-        self.opts.debugging_opts.count_llvm_insns
-    }
     pub fn time_llvm_passes(&self) -> bool {
         self.opts.debugging_opts.time_llvm_passes
     }
-    pub fn codegen_stats(&self) -> bool {
-        self.opts.debugging_opts.codegen_stats
-    }
     pub fn meta_stats(&self) -> bool {
         self.opts.debugging_opts.meta_stats
     }
diff --git a/src/librustc_codegen_llvm/base.rs b/src/librustc_codegen_llvm/base.rs
index 9077e89a402..f8c6087373f 100644
--- a/src/librustc_codegen_llvm/base.rs
+++ b/src/librustc_codegen_llvm/base.rs
@@ -24,7 +24,7 @@ use crate::common;
 use crate::context::CodegenCx;
 use crate::monomorphize::partitioning::CodegenUnitExt;
 use rustc::dep_graph;
-use rustc::mir::mono::{Linkage, Visibility, Stats};
+use rustc::mir::mono::{Linkage, Visibility};
 use rustc::middle::cstore::{EncodedMetadata};
 use rustc::ty::TyCtxt;
 use rustc::middle::exported_symbols;
@@ -104,17 +104,17 @@ pub fn iter_globals(llmod: &'ll llvm::Module) -> ValueIter<'ll> {
     }
 }
 
-pub fn compile_codegen_unit<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                                  cgu_name: InternedString)
-                                  -> Stats {
+pub fn compile_codegen_unit(tcx: TyCtxt<'a, 'tcx, 'tcx>, cgu_name: InternedString) {
     let start_time = Instant::now();
 
     let dep_node = tcx.codegen_unit(cgu_name).codegen_dep_node(tcx);
-    let ((stats, module), _) = tcx.dep_graph.with_task(dep_node,
-                                                       tcx,
-                                                       cgu_name,
-                                                       module_codegen,
-                                                       dep_graph::hash_result);
+    let (module, _) = tcx.dep_graph.with_task(
+        dep_node,
+        tcx,
+        cgu_name,
+        module_codegen,
+        dep_graph::hash_result,
+    );
     let time_to_codegen = start_time.elapsed();
 
     // We assume that the cost to run LLVM on a CGU is proportional to
@@ -123,17 +123,15 @@ pub fn compile_codegen_unit<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                time_to_codegen.subsec_nanos() as u64;
 
     submit_codegened_module_to_llvm(&LlvmCodegenBackend(()), tcx, module, cost);
-    return stats;
 
     fn module_codegen<'ll, 'tcx>(
         tcx: TyCtxt<'ll, 'tcx, 'tcx>,
-        cgu_name: InternedString)
-        -> (Stats, ModuleCodegen<ModuleLlvm>)
-    {
+        cgu_name: InternedString,
+    ) -> ModuleCodegen<ModuleLlvm> {
         let cgu = tcx.codegen_unit(cgu_name);
         // Instantiate monomorphizations without filling out definitions yet...
         let llvm_module = ModuleLlvm::new(tcx, &cgu_name.as_str());
-        let stats = {
+        {
             let cx = CodegenCx::new(tcx, cgu, &llvm_module);
             let mono_items = cx.codegen_unit
                                .items_in_deterministic_order(cx.tcx);
@@ -169,15 +167,13 @@ pub fn compile_codegen_unit<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
             if cx.sess().opts.debuginfo != DebugInfo::None {
                 cx.debuginfo_finalize();
             }
+        }
 
-            cx.consume_stats().into_inner()
-        };
-
-        (stats, ModuleCodegen {
+        ModuleCodegen {
             name: cgu_name.to_string(),
             module_llvm: llvm_module,
             kind: ModuleKind::Regular,
-        })
+        }
     }
 }
 
diff --git a/src/librustc_codegen_llvm/builder.rs b/src/librustc_codegen_llvm/builder.rs
index 48808eea304..42e7a72c43b 100644
--- a/src/librustc_codegen_llvm/builder.rs
+++ b/src/librustc_codegen_llvm/builder.rs
@@ -147,21 +147,18 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn ret_void(&mut self) {
-        self.count_insn("retvoid");
         unsafe {
             llvm::LLVMBuildRetVoid(self.llbuilder);
         }
     }
 
     fn ret(&mut self, v: &'ll Value) {
-        self.count_insn("ret");
         unsafe {
             llvm::LLVMBuildRet(self.llbuilder, v);
         }
     }
 
     fn br(&mut self, dest: &'ll BasicBlock) {
-        self.count_insn("br");
         unsafe {
             llvm::LLVMBuildBr(self.llbuilder, dest);
         }
@@ -173,7 +170,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         then_llbb: &'ll BasicBlock,
         else_llbb: &'ll BasicBlock,
     ) {
-        self.count_insn("condbr");
         unsafe {
             llvm::LLVMBuildCondBr(self.llbuilder, cond, then_llbb, else_llbb);
         }
@@ -204,7 +200,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         catch: &'ll BasicBlock,
         funclet: Option<&Funclet<'ll>>,
     ) -> &'ll Value {
-        self.count_insn("invoke");
 
         debug!("Invoke {:?} with args ({:?})",
                llfn,
@@ -227,7 +222,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn unreachable(&mut self) {
-        self.count_insn("unreachable");
         unsafe {
             llvm::LLVMBuildUnreachable(self.llbuilder);
         }
@@ -235,21 +229,18 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
 
     /* Arithmetic */
     fn add(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("add");
         unsafe {
             llvm::LLVMBuildAdd(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn fadd(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("fadd");
         unsafe {
             llvm::LLVMBuildFAdd(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn fadd_fast(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("fadd");
         unsafe {
             let instr = llvm::LLVMBuildFAdd(self.llbuilder, lhs, rhs, noname());
             llvm::LLVMRustSetHasUnsafeAlgebra(instr);
@@ -258,21 +249,18 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn sub(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("sub");
         unsafe {
             llvm::LLVMBuildSub(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn fsub(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("fsub");
         unsafe {
             llvm::LLVMBuildFSub(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn fsub_fast(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("fsub");
         unsafe {
             let instr = llvm::LLVMBuildFSub(self.llbuilder, lhs, rhs, noname());
             llvm::LLVMRustSetHasUnsafeAlgebra(instr);
@@ -281,21 +269,18 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn mul(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("mul");
         unsafe {
             llvm::LLVMBuildMul(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn fmul(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("fmul");
         unsafe {
             llvm::LLVMBuildFMul(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn fmul_fast(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("fmul");
         unsafe {
             let instr = llvm::LLVMBuildFMul(self.llbuilder, lhs, rhs, noname());
             llvm::LLVMRustSetHasUnsafeAlgebra(instr);
@@ -305,42 +290,36 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
 
 
     fn udiv(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("udiv");
         unsafe {
             llvm::LLVMBuildUDiv(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn exactudiv(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("exactudiv");
         unsafe {
             llvm::LLVMBuildExactUDiv(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn sdiv(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("sdiv");
         unsafe {
             llvm::LLVMBuildSDiv(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn exactsdiv(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("exactsdiv");
         unsafe {
             llvm::LLVMBuildExactSDiv(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn fdiv(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("fdiv");
         unsafe {
             llvm::LLVMBuildFDiv(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn fdiv_fast(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("fdiv");
         unsafe {
             let instr = llvm::LLVMBuildFDiv(self.llbuilder, lhs, rhs, noname());
             llvm::LLVMRustSetHasUnsafeAlgebra(instr);
@@ -349,28 +328,24 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn urem(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("urem");
         unsafe {
             llvm::LLVMBuildURem(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn srem(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("srem");
         unsafe {
             llvm::LLVMBuildSRem(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn frem(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("frem");
         unsafe {
             llvm::LLVMBuildFRem(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn frem_fast(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("frem");
         unsafe {
             let instr = llvm::LLVMBuildFRem(self.llbuilder, lhs, rhs, noname());
             llvm::LLVMRustSetHasUnsafeAlgebra(instr);
@@ -379,63 +354,54 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn shl(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("shl");
         unsafe {
             llvm::LLVMBuildShl(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn lshr(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("lshr");
         unsafe {
             llvm::LLVMBuildLShr(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn ashr(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("ashr");
         unsafe {
             llvm::LLVMBuildAShr(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn and(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("and");
         unsafe {
             llvm::LLVMBuildAnd(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn or(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("or");
         unsafe {
             llvm::LLVMBuildOr(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn xor(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("xor");
         unsafe {
             llvm::LLVMBuildXor(self.llbuilder, lhs, rhs, noname())
         }
     }
 
     fn neg(&mut self, v: &'ll Value) -> &'ll Value {
-        self.count_insn("neg");
         unsafe {
             llvm::LLVMBuildNeg(self.llbuilder, v, noname())
         }
     }
 
     fn fneg(&mut self, v: &'ll Value) -> &'ll Value {
-        self.count_insn("fneg");
         unsafe {
             llvm::LLVMBuildFNeg(self.llbuilder, v, noname())
         }
     }
 
     fn not(&mut self, v: &'ll Value) -> &'ll Value {
-        self.count_insn("not");
         unsafe {
             llvm::LLVMBuildNot(self.llbuilder, v, noname())
         }
@@ -524,7 +490,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn dynamic_alloca(&mut self, ty: &'ll Type, name: &str, align: Align) -> &'ll Value {
-        self.count_insn("alloca");
         unsafe {
             let alloca = if name.is_empty() {
                 llvm::LLVMBuildAlloca(self.llbuilder, ty, noname())
@@ -543,7 +508,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
                         len: &'ll Value,
                         name: &str,
                         align: Align) -> &'ll Value {
-        self.count_insn("alloca");
         unsafe {
             let alloca = if name.is_empty() {
                 llvm::LLVMBuildArrayAlloca(self.llbuilder, ty, len, noname())
@@ -558,7 +522,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn load(&mut self, ptr: &'ll Value, align: Align) -> &'ll Value {
-        self.count_insn("load");
         unsafe {
             let load = llvm::LLVMBuildLoad(self.llbuilder, ptr, noname());
             llvm::LLVMSetAlignment(load, align.bytes() as c_uint);
@@ -567,11 +530,10 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn volatile_load(&mut self, ptr: &'ll Value) -> &'ll Value {
-        self.count_insn("load.volatile");
         unsafe {
-            let insn = llvm::LLVMBuildLoad(self.llbuilder, ptr, noname());
-            llvm::LLVMSetVolatile(insn, llvm::True);
-            insn
+            let load = llvm::LLVMBuildLoad(self.llbuilder, ptr, noname());
+            llvm::LLVMSetVolatile(load, llvm::True);
+            load
         }
     }
 
@@ -581,7 +543,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         order: rustc_codegen_ssa::common::AtomicOrdering,
         size: Size,
     ) -> &'ll Value {
-        self.count_insn("load.atomic");
         unsafe {
             let load = llvm::LLVMRustBuildAtomicLoad(
                 self.llbuilder,
@@ -745,7 +706,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         flags: MemFlags,
     ) -> &'ll Value {
         debug!("Store {:?} -> {:?} ({:?})", val, ptr, flags);
-        self.count_insn("store");
         let ptr = self.check_store(val, ptr);
         unsafe {
             let store = llvm::LLVMBuildStore(self.llbuilder, val, ptr);
@@ -774,7 +734,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
    fn atomic_store(&mut self, val: &'ll Value, ptr: &'ll Value,
                    order: rustc_codegen_ssa::common::AtomicOrdering, size: Size) {
         debug!("Store {:?} -> {:?}", val, ptr);
-        self.count_insn("store.atomic");
         let ptr = self.check_store(val, ptr);
         unsafe {
             let store = llvm::LLVMRustBuildAtomicStore(
@@ -789,7 +748,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn gep(&mut self, ptr: &'ll Value, indices: &[&'ll Value]) -> &'ll Value {
-        self.count_insn("gep");
         unsafe {
             llvm::LLVMBuildGEP(self.llbuilder, ptr, indices.as_ptr(),
                                indices.len() as c_uint, noname())
@@ -797,7 +755,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn inbounds_gep(&mut self, ptr: &'ll Value, indices: &[&'ll Value]) -> &'ll Value {
-        self.count_insn("inboundsgep");
         unsafe {
             llvm::LLVMBuildInBoundsGEP(
                 self.llbuilder, ptr, indices.as_ptr(), indices.len() as c_uint, noname())
@@ -805,7 +762,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn struct_gep(&mut self, ptr: &'ll Value, idx: u64) -> &'ll Value {
-        self.count_insn("structgep");
         assert_eq!(idx as c_uint as u64, idx);
         unsafe {
             llvm::LLVMBuildStructGEP(self.llbuilder, ptr, idx as c_uint, noname())
@@ -814,77 +770,66 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
 
     /* Casts */
     fn trunc(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
-        self.count_insn("trunc");
         unsafe {
             llvm::LLVMBuildTrunc(self.llbuilder, val, dest_ty, noname())
         }
     }
 
     fn sext(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
-        self.count_insn("sext");
         unsafe {
             llvm::LLVMBuildSExt(self.llbuilder, val, dest_ty, noname())
         }
     }
 
     fn fptoui(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
-        self.count_insn("fptoui");
         unsafe {
             llvm::LLVMBuildFPToUI(self.llbuilder, val, dest_ty, noname())
         }
     }
 
     fn fptosi(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
-        self.count_insn("fptosi");
         unsafe {
             llvm::LLVMBuildFPToSI(self.llbuilder, val, dest_ty,noname())
         }
     }
 
     fn uitofp(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
-        self.count_insn("uitofp");
         unsafe {
             llvm::LLVMBuildUIToFP(self.llbuilder, val, dest_ty, noname())
         }
     }
 
     fn sitofp(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
-        self.count_insn("sitofp");
         unsafe {
             llvm::LLVMBuildSIToFP(self.llbuilder, val, dest_ty, noname())
         }
     }
 
     fn fptrunc(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
-        self.count_insn("fptrunc");
         unsafe {
             llvm::LLVMBuildFPTrunc(self.llbuilder, val, dest_ty, noname())
         }
     }
 
     fn fpext(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
-        self.count_insn("fpext");
         unsafe {
             llvm::LLVMBuildFPExt(self.llbuilder, val, dest_ty, noname())
         }
     }
 
     fn ptrtoint(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
-        self.count_insn("ptrtoint");
         unsafe {
             llvm::LLVMBuildPtrToInt(self.llbuilder, val, dest_ty, noname())
         }
     }
 
     fn inttoptr(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
-        self.count_insn("inttoptr");
         unsafe {
             llvm::LLVMBuildIntToPtr(self.llbuilder, val, dest_ty, noname())
         }
     }
 
     fn bitcast(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
-        self.count_insn("bitcast");
         unsafe {
             llvm::LLVMBuildBitCast(self.llbuilder, val, dest_ty, noname())
         }
@@ -892,14 +837,12 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
 
 
     fn intcast(&mut self, val: &'ll Value, dest_ty: &'ll Type, is_signed: bool) -> &'ll Value {
-        self.count_insn("intcast");
         unsafe {
             llvm::LLVMRustBuildIntCast(self.llbuilder, val, dest_ty, is_signed)
         }
     }
 
     fn pointercast(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
-        self.count_insn("pointercast");
         unsafe {
             llvm::LLVMBuildPointerCast(self.llbuilder, val, dest_ty, noname())
         }
@@ -907,7 +850,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
 
     /* Comparisons */
     fn icmp(&mut self, op: IntPredicate, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("icmp");
         let op = llvm::IntPredicate::from_generic(op);
         unsafe {
             llvm::LLVMBuildICmp(self.llbuilder, op as c_uint, lhs, rhs, noname())
@@ -915,7 +857,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn fcmp(&mut self, op: RealPredicate, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("fcmp");
         unsafe {
             llvm::LLVMBuildFCmp(self.llbuilder, op as c_uint, lhs, rhs, noname())
         }
@@ -984,7 +925,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         then_val: &'ll Value,
         else_val: &'ll Value,
     ) -> &'ll Value {
-        self.count_insn("select");
         unsafe {
             llvm::LLVMBuildSelect(self.llbuilder, cond, then_val, else_val, noname())
         }
@@ -992,14 +932,12 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
 
     #[allow(dead_code)]
     fn va_arg(&mut self, list: &'ll Value, ty: &'ll Type) -> &'ll Value {
-        self.count_insn("vaarg");
         unsafe {
             llvm::LLVMBuildVAArg(self.llbuilder, list, ty, noname())
         }
     }
 
     fn extract_element(&mut self, vec: &'ll Value, idx: &'ll Value) -> &'ll Value {
-        self.count_insn("extractelement");
         unsafe {
             llvm::LLVMBuildExtractElement(self.llbuilder, vec, idx, noname())
         }
@@ -1016,7 +954,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn extract_value(&mut self, agg_val: &'ll Value, idx: u64) -> &'ll Value {
-        self.count_insn("extractvalue");
         assert_eq!(idx as c_uint as u64, idx);
         unsafe {
             llvm::LLVMBuildExtractValue(self.llbuilder, agg_val, idx as c_uint, noname())
@@ -1025,7 +962,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
 
     fn insert_value(&mut self, agg_val: &'ll Value, elt: &'ll Value,
                        idx: u64) -> &'ll Value {
-        self.count_insn("insertvalue");
         assert_eq!(idx as c_uint as u64, idx);
         unsafe {
             llvm::LLVMBuildInsertValue(self.llbuilder, agg_val, elt, idx as c_uint,
@@ -1035,7 +971,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
 
     fn landing_pad(&mut self, ty: &'ll Type, pers_fn: &'ll Value,
                        num_clauses: usize) -> &'ll Value {
-        self.count_insn("landingpad");
         unsafe {
             llvm::LLVMBuildLandingPad(self.llbuilder, ty, pers_fn,
                                       num_clauses as c_uint, noname())
@@ -1043,14 +978,12 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn set_cleanup(&mut self, landing_pad: &'ll Value) {
-        self.count_insn("setcleanup");
         unsafe {
             llvm::LLVMSetCleanup(landing_pad, llvm::True);
         }
     }
 
     fn resume(&mut self, exn: &'ll Value) -> &'ll Value {
-        self.count_insn("resume");
         unsafe {
             llvm::LLVMBuildResume(self.llbuilder, exn)
         }
@@ -1059,7 +992,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     fn cleanup_pad(&mut self,
                        parent: Option<&'ll Value>,
                        args: &[&'ll Value]) -> Funclet<'ll> {
-        self.count_insn("cleanuppad");
         let name = const_cstr!("cleanuppad");
         let ret = unsafe {
             llvm::LLVMRustBuildCleanupPad(self.llbuilder,
@@ -1075,7 +1007,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         &mut self, funclet: &Funclet<'ll>,
         unwind: Option<&'ll BasicBlock>,
     ) -> &'ll Value {
-        self.count_insn("cleanupret");
         let ret = unsafe {
             llvm::LLVMRustBuildCleanupRet(self.llbuilder, funclet.cleanuppad(), unwind)
         };
@@ -1085,7 +1016,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     fn catch_pad(&mut self,
                      parent: &'ll Value,
                      args: &[&'ll Value]) -> Funclet<'ll> {
-        self.count_insn("catchpad");
         let name = const_cstr!("catchpad");
         let ret = unsafe {
             llvm::LLVMRustBuildCatchPad(self.llbuilder, parent,
@@ -1101,7 +1031,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         unwind: Option<&'ll BasicBlock>,
         num_handlers: usize,
     ) -> &'ll Value {
-        self.count_insn("catchswitch");
         let name = const_cstr!("catchswitch");
         let ret = unsafe {
             llvm::LLVMRustBuildCatchSwitch(self.llbuilder, parent, unwind,
@@ -1199,7 +1128,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         args: &[&'ll Value],
         funclet: Option<&Funclet<'ll>>,
     ) -> &'ll Value {
-        self.count_insn("call");
 
         debug!("Call {:?} with args ({:?})",
                llfn,
@@ -1221,7 +1149,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn zext(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
-        self.count_insn("zext");
         unsafe {
             llvm::LLVMBuildZExt(self.llbuilder, val, dest_ty, noname())
         }
@@ -1285,19 +1212,6 @@ impl Builder<'a, 'll, 'tcx> {
         }
     }
 
-    fn count_insn(&self, category: &str) {
-        if self.sess().codegen_stats() {
-            self.stats.borrow_mut().n_llvm_insns += 1;
-        }
-        if self.sess().count_llvm_insns() {
-            *self.stats
-                      .borrow_mut()
-                      .llvm_insns
-                      .entry(category.to_string())
-                      .or_insert(0) += 1;
-        }
-    }
-
     fn position_at_start(&mut self, llbb: &'ll BasicBlock) {
         unsafe {
             llvm::LLVMRustPositionBuilderAtStart(self.llbuilder, llbb);
@@ -1305,12 +1219,10 @@ impl Builder<'a, 'll, 'tcx> {
     }
 
     pub fn minnum(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("minnum");
         unsafe { llvm::LLVMRustBuildMinNum(self.llbuilder, lhs, rhs) }
     }
 
     pub fn maxnum(&mut self, lhs: &'ll Value, rhs: &'ll Value) -> &'ll Value {
-        self.count_insn("maxnum");
         unsafe { llvm::LLVMRustBuildMaxNum(self.llbuilder, lhs, rhs) }
     }
 
@@ -1319,7 +1231,6 @@ impl Builder<'a, 'll, 'tcx> {
         elt: &'ll Value,
         idx: &'ll Value,
     ) -> &'ll Value {
-        self.count_insn("insertelement");
         unsafe {
             llvm::LLVMBuildInsertElement(self.llbuilder, vec, elt, idx, noname())
         }
@@ -1331,14 +1242,12 @@ impl Builder<'a, 'll, 'tcx> {
         v2: &'ll Value,
         mask: &'ll Value,
     ) -> &'ll Value {
-        self.count_insn("shufflevector");
         unsafe {
             llvm::LLVMBuildShuffleVector(self.llbuilder, v1, v2, mask, noname())
         }
     }
 
     pub fn vector_reduce_fadd_fast(&mut self, acc: &'ll Value, src: &'ll Value) -> &'ll Value {
-        self.count_insn("vector.reduce.fadd_fast");
         unsafe {
             // FIXME: add a non-fast math version once
             // https://bugs.llvm.org/show_bug.cgi?id=36732
@@ -1349,7 +1258,6 @@ impl Builder<'a, 'll, 'tcx> {
         }
     }
     pub fn vector_reduce_fmul_fast(&mut self, acc: &'ll Value, src: &'ll Value) -> &'ll Value {
-        self.count_insn("vector.reduce.fmul_fast");
         unsafe {
             // FIXME: add a non-fast math version once
             // https://bugs.llvm.org/show_bug.cgi?id=36732
@@ -1360,35 +1268,27 @@ impl Builder<'a, 'll, 'tcx> {
         }
     }
     pub fn vector_reduce_add(&mut self, src: &'ll Value) -> &'ll Value {
-        self.count_insn("vector.reduce.add");
         unsafe { llvm::LLVMRustBuildVectorReduceAdd(self.llbuilder, src) }
     }
     pub fn vector_reduce_mul(&mut self, src: &'ll Value) -> &'ll Value {
-        self.count_insn("vector.reduce.mul");
         unsafe { llvm::LLVMRustBuildVectorReduceMul(self.llbuilder, src) }
     }
     pub fn vector_reduce_and(&mut self, src: &'ll Value) -> &'ll Value {
-        self.count_insn("vector.reduce.and");
         unsafe { llvm::LLVMRustBuildVectorReduceAnd(self.llbuilder, src) }
     }
     pub fn vector_reduce_or(&mut self, src: &'ll Value) -> &'ll Value {
-        self.count_insn("vector.reduce.or");
         unsafe { llvm::LLVMRustBuildVectorReduceOr(self.llbuilder, src) }
     }
     pub fn vector_reduce_xor(&mut self, src: &'ll Value) -> &'ll Value {
-        self.count_insn("vector.reduce.xor");
         unsafe { llvm::LLVMRustBuildVectorReduceXor(self.llbuilder, src) }
     }
     pub fn vector_reduce_fmin(&mut self, src: &'ll Value) -> &'ll Value {
-        self.count_insn("vector.reduce.fmin");
         unsafe { llvm::LLVMRustBuildVectorReduceFMin(self.llbuilder, src, /*NoNaNs:*/ false) }
     }
     pub fn vector_reduce_fmax(&mut self, src: &'ll Value) -> &'ll Value {
-        self.count_insn("vector.reduce.fmax");
         unsafe { llvm::LLVMRustBuildVectorReduceFMax(self.llbuilder, src, /*NoNaNs:*/ false) }
     }
     pub fn vector_reduce_fmin_fast(&mut self, src: &'ll Value) -> &'ll Value {
-        self.count_insn("vector.reduce.fmin_fast");
         unsafe {
             let instr = llvm::LLVMRustBuildVectorReduceFMin(self.llbuilder, src, /*NoNaNs:*/ true);
             llvm::LLVMRustSetHasUnsafeAlgebra(instr);
@@ -1396,7 +1296,6 @@ impl Builder<'a, 'll, 'tcx> {
         }
     }
     pub fn vector_reduce_fmax_fast(&mut self, src: &'ll Value) -> &'ll Value {
-        self.count_insn("vector.reduce.fmax_fast");
         unsafe {
             let instr = llvm::LLVMRustBuildVectorReduceFMax(self.llbuilder, src, /*NoNaNs:*/ true);
             llvm::LLVMRustSetHasUnsafeAlgebra(instr);
@@ -1404,11 +1303,9 @@ impl Builder<'a, 'll, 'tcx> {
         }
     }
     pub fn vector_reduce_min(&mut self, src: &'ll Value, is_signed: bool) -> &'ll Value {
-        self.count_insn("vector.reduce.min");
         unsafe { llvm::LLVMRustBuildVectorReduceMin(self.llbuilder, src, is_signed) }
     }
     pub fn vector_reduce_max(&mut self, src: &'ll Value, is_signed: bool) -> &'ll Value {
-        self.count_insn("vector.reduce.max");
         unsafe { llvm::LLVMRustBuildVectorReduceMax(self.llbuilder, src, is_signed) }
     }
 
@@ -1419,7 +1316,6 @@ impl Builder<'a, 'll, 'tcx> {
     }
 
     pub fn catch_ret(&mut self, funclet: &Funclet<'ll>, unwind: &'ll BasicBlock) -> &'ll Value {
-        self.count_insn("catchret");
         let ret = unsafe {
             llvm::LLVMRustBuildCatchRet(self.llbuilder, funclet.cleanuppad(), unwind)
         };
@@ -1488,7 +1384,6 @@ impl Builder<'a, 'll, 'tcx> {
     }
 
     pub fn va_arg(&mut self, list: &'ll Value, ty: &'ll Type) -> &'ll Value {
-        self.count_insn("vaarg");
         unsafe {
             llvm::LLVMBuildVAArg(self.llbuilder, list, ty, noname())
         }
@@ -1511,7 +1406,6 @@ impl Builder<'a, 'll, 'tcx> {
     }
 
     fn phi(&mut self, ty: &'ll Type, vals: &[&'ll Value], bbs: &[&'ll BasicBlock]) -> &'ll Value {
-        self.count_insn("addincoming");
         assert_eq!(vals.len(), bbs.len());
         let phi = unsafe {
             llvm::LLVMBuildPhi(self.llbuilder, ty, noname())
@@ -1525,7 +1419,6 @@ impl Builder<'a, 'll, 'tcx> {
     }
 
     fn add_incoming_to_phi(&mut self, phi: &'ll Value, val: &'ll Value, bb: &'ll BasicBlock) {
-        self.count_insn("addincoming");
         unsafe {
             llvm::LLVMAddIncoming(phi, &val, &bb, 1 as c_uint);
         }
diff --git a/src/librustc_codegen_llvm/context.rs b/src/librustc_codegen_llvm/context.rs
index 7bf8f705ea8..b6b47d047c8 100644
--- a/src/librustc_codegen_llvm/context.rs
+++ b/src/librustc_codegen_llvm/context.rs
@@ -12,7 +12,6 @@ use rustc_codegen_ssa::traits::*;
 
 use rustc_data_structures::base_n;
 use rustc_data_structures::small_c_str::SmallCStr;
-use rustc::mir::mono::Stats;
 use rustc::session::config::{self, DebugInfo};
 use rustc::session::Session;
 use rustc::ty::layout::{
@@ -44,7 +43,6 @@ pub struct CodegenCx<'ll, 'tcx: 'll> {
 
     pub llmod: &'ll llvm::Module,
     pub llcx: &'ll llvm::Context,
-    pub stats: RefCell<Stats>,
     pub codegen_unit: Arc<CodegenUnit<'tcx>>,
 
     /// Cache instances of monomorphic and polymorphic items
@@ -284,7 +282,6 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
             tls_model,
             llmod,
             llcx,
-            stats: RefCell::new(Stats::default()),
             codegen_unit,
             instances: Default::default(),
             vtables: Default::default(),
@@ -408,14 +405,6 @@ impl MiscMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         self.check_overflow
     }
 
-    fn stats(&self) -> &RefCell<Stats> {
-        &self.stats
-    }
-
-    fn consume_stats(self) -> RefCell<Stats> {
-        self.stats
-    }
-
     fn codegen_unit(&self) -> &Arc<CodegenUnit<'tcx>> {
         &self.codegen_unit
     }
diff --git a/src/librustc_codegen_llvm/lib.rs b/src/librustc_codegen_llvm/lib.rs
index 09b284052b3..57cffa48163 100644
--- a/src/librustc_codegen_llvm/lib.rs
+++ b/src/librustc_codegen_llvm/lib.rs
@@ -52,7 +52,6 @@ use rustc_codegen_ssa::CompiledModule;
 use errors::{FatalError, Handler};
 use rustc::dep_graph::WorkProduct;
 use syntax_pos::symbol::InternedString;
-use rustc::mir::mono::Stats;
 pub use llvm_util::target_features;
 use std::any::Any;
 use std::sync::{mpsc, Arc};
@@ -130,8 +129,8 @@ impl ExtraBackendMethods for LlvmCodegenBackend {
         &self,
         tcx: TyCtxt<'a, 'tcx, 'tcx>,
         cgu_name: InternedString,
-    ) -> Stats {
-        base::compile_codegen_unit(tcx, cgu_name)
+    ) {
+        base::compile_codegen_unit(tcx, cgu_name);
     }
     fn target_machine_factory(
         &self,
diff --git a/src/librustc_codegen_ssa/base.rs b/src/librustc_codegen_ssa/base.rs
index 0b037f87247..172b5b39987 100644
--- a/src/librustc_codegen_ssa/base.rs
+++ b/src/librustc_codegen_ssa/base.rs
@@ -20,7 +20,7 @@ use rustc::hir::def_id::{DefId, LOCAL_CRATE};
 use rustc::middle::cstore::EncodedMetadata;
 use rustc::middle::lang_items::StartFnLangItem;
 use rustc::middle::weak_lang_items;
-use rustc::mir::mono::{Stats, CodegenUnitNameBuilder};
+use rustc::mir::mono::CodegenUnitNameBuilder;
 use rustc::ty::{self, Ty, TyCtxt};
 use rustc::ty::layout::{self, Align, TyLayout, LayoutOf, VariantIdx, HasTyCtxt};
 use rustc::ty::query::Providers;
@@ -28,7 +28,6 @@ use rustc::middle::cstore::{self, LinkagePreference};
 use rustc::util::common::{time, print_time_passes_entry};
 use rustc::session::config::{self, EntryFnType, Lto};
 use rustc::session::Session;
-use rustc_mir::monomorphize::item::DefPathBasedNames;
 use rustc_mir::monomorphize::Instance;
 use rustc_mir::monomorphize::partitioning::{CodegenUnit, CodegenUnitExt};
 use rustc::util::nodemap::FxHashMap;
@@ -58,40 +57,6 @@ use rustc::hir;
 
 use crate::mir::operand::OperandValue;
 
-use std::marker::PhantomData;
-
-pub struct StatRecorder<'a, 'tcx, Cx: 'a + CodegenMethods<'tcx>> {
-    cx: &'a Cx,
-    name: Option<String>,
-    istart: usize,
-    _marker: PhantomData<&'tcx ()>,
-}
-
-impl<'a, 'tcx, Cx: CodegenMethods<'tcx>> StatRecorder<'a, 'tcx, Cx> {
-    pub fn new(cx: &'a Cx, name: String) -> Self {
-        let istart = cx.stats().borrow().n_llvm_insns;
-        StatRecorder {
-            cx,
-            name: Some(name),
-            istart,
-            _marker: PhantomData,
-        }
-    }
-}
-
-impl<'a, 'tcx, Cx: CodegenMethods<'tcx>> Drop for StatRecorder<'a, 'tcx, Cx> {
-    fn drop(&mut self) {
-        if self.cx.sess().codegen_stats() {
-            let mut stats = self.cx.stats().borrow_mut();
-            let iend = stats.n_llvm_insns;
-            stats.fn_stats.push((self.name.take().unwrap(), iend - self.istart));
-            stats.n_fns += 1;
-            // Reset LLVM insn count to avoid compound costs.
-            stats.n_llvm_insns = self.istart;
-        }
-    }
-}
-
 pub fn bin_op_to_icmp_predicate(op: hir::BinOpKind,
                                 signed: bool)
                                 -> IntPredicate {
@@ -408,15 +373,6 @@ pub fn codegen_instance<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>>(
     cx: &'a Bx::CodegenCx,
     instance: Instance<'tcx>,
 ) {
-    let _s = if cx.sess().codegen_stats() {
-        let mut instance_name = String::new();
-        DefPathBasedNames::new(cx.tcx(), true, true)
-            .push_def_path(instance.def_id(), &mut instance_name);
-        Some(StatRecorder::new(cx, instance_name))
-    } else {
-        None
-    };
-
     // this is an info! to allow collecting monomorphization statistics
     // and to allow finding the last function before LLVM aborts from
     // release builds.
@@ -428,8 +384,6 @@ pub fn codegen_instance<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>>(
     let lldecl = cx.instances().borrow().get(&instance).cloned().unwrap_or_else(||
         bug!("Instance `{:?}` not already declared", instance));
 
-    cx.stats().borrow_mut().n_closures += 1;
-
     let mir = cx.tcx().instance_mir(instance.def);
     mir::codegen_mir::<Bx>(cx, lldecl, &mir, instance, sig);
 }
@@ -653,7 +607,6 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
     };
 
     let mut total_codegen_time = Duration::new(0, 0);
-    let mut all_stats = Stats::default();
 
     for cgu in codegen_units.into_iter() {
         ongoing_codegen.wait_for_signal_to_codegen_item();
@@ -666,8 +619,7 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
             CguReuse::No => {
                 tcx.sess.profiler(|p| p.start_activity(format!("codegen {}", cgu.name())));
                 let start_time = Instant::now();
-                let stats = backend.compile_codegen_unit(tcx, *cgu.name());
-                all_stats.extend(stats);
+                backend.compile_codegen_unit(tcx, *cgu.name());
                 total_codegen_time += start_time.elapsed();
                 tcx.sess.profiler(|p| p.end_activity(format!("codegen {}", cgu.name())));
                 false
@@ -701,28 +653,6 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
 
     symbol_names_test::report_symbol_names(tcx);
 
-    if tcx.sess.codegen_stats() {
-        println!("--- codegen stats ---");
-        println!("n_glues_created: {}", all_stats.n_glues_created);
-        println!("n_null_glues: {}", all_stats.n_null_glues);
-        println!("n_real_glues: {}", all_stats.n_real_glues);
-
-        println!("n_fns: {}", all_stats.n_fns);
-        println!("n_inlines: {}", all_stats.n_inlines);
-        println!("n_closures: {}", all_stats.n_closures);
-        println!("fn stats:");
-        all_stats.fn_stats.sort_by_key(|&(_, insns)| insns);
-        for &(ref name, insns) in all_stats.fn_stats.iter() {
-            println!("{} insns, {}", insns, *name);
-        }
-    }
-
-    if tcx.sess.count_llvm_insns() {
-        for (k, v) in all_stats.llvm_insns.iter() {
-            println!("{:7} {}", *v, *k);
-        }
-    }
-
     ongoing_codegen.check_for_errors(tcx.sess);
 
     assert_and_save_dep_graph(tcx);
diff --git a/src/librustc_codegen_ssa/mir/place.rs b/src/librustc_codegen_ssa/mir/place.rs
index 670b6c47269..cd32d6f484d 100644
--- a/src/librustc_codegen_ssa/mir/place.rs
+++ b/src/librustc_codegen_ssa/mir/place.rs
@@ -396,22 +396,20 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         let cx = self.cx;
         let tcx = self.cx.tcx();
 
-        if let mir::Place::Base(mir::PlaceBase::Local(index)) = *place {
-            match self.locals[index] {
-                LocalRef::Place(place) => {
-                    return place;
-                }
-                LocalRef::UnsizedPlace(place) => {
-                    return bx.load_operand(place).deref(cx);
-                }
-                LocalRef::Operand(..) => {
-                    bug!("using operand local {:?} as place", place);
+        let result = match *place {
+            mir::Place::Base(mir::PlaceBase::Local(index)) => {
+                match self.locals[index] {
+                    LocalRef::Place(place) => {
+                        return place;
+                    }
+                    LocalRef::UnsizedPlace(place) => {
+                        return bx.load_operand(place).deref(cx);
+                    }
+                    LocalRef::Operand(..) => {
+                        bug!("using operand local {:?} as place", place);
+                    }
                 }
             }
-        }
-
-        let result = match *place {
-            mir::Place::Base(mir::PlaceBase::Local(_)) => bug!(), // handled above
             mir::Place::Base(
                 mir::PlaceBase::Static(
                     box mir::Static { ty, kind: mir::StaticKind::Promoted(promoted) }
diff --git a/src/librustc_codegen_ssa/traits/backend.rs b/src/librustc_codegen_ssa/traits/backend.rs
index 530eba516a6..0466b47cf14 100644
--- a/src/librustc_codegen_ssa/traits/backend.rs
+++ b/src/librustc_codegen_ssa/traits/backend.rs
@@ -5,7 +5,6 @@ use super::write::WriteBackendMethods;
 use super::CodegenObject;
 use rustc::middle::allocator::AllocatorKind;
 use rustc::middle::cstore::EncodedMetadata;
-use rustc::mir::mono::Stats;
 use rustc::session::{Session, config};
 use rustc::ty::TyCtxt;
 use rustc_codegen_utils::codegen_backend::CodegenBackend;
@@ -49,7 +48,7 @@ pub trait ExtraBackendMethods: CodegenBackend + WriteBackendMethods + Sized + Se
         &self,
         tcx: TyCtxt<'a, 'tcx, 'tcx>,
         cgu_name: InternedString,
-    ) -> Stats;
+    );
     // If find_features is true this won't access `sess.crate_types` by assuming
     // that `is_pie_binary` is false. When we discover LLVM target features
     // `sess.crate_types` is uninitialized so we cannot access it.
diff --git a/src/librustc_codegen_ssa/traits/misc.rs b/src/librustc_codegen_ssa/traits/misc.rs
index 2797dd89f5b..5ea86df6e94 100644
--- a/src/librustc_codegen_ssa/traits/misc.rs
+++ b/src/librustc_codegen_ssa/traits/misc.rs
@@ -1,5 +1,4 @@
 use super::BackendTypes;
-use rustc::mir::mono::Stats;
 use rustc::session::Session;
 use rustc::ty::{self, Instance, Ty};
 use rustc::util::nodemap::FxHashMap;
@@ -17,8 +16,6 @@ pub trait MiscMethods<'tcx>: BackendTypes {
     fn eh_personality(&self) -> Self::Value;
     fn eh_unwind_resume(&self) -> Self::Value;
     fn sess(&self) -> &Session;
-    fn stats(&self) -> &RefCell<Stats>;
-    fn consume_stats(self) -> RefCell<Stats>;
     fn codegen_unit(&self) -> &Arc<CodegenUnit<'tcx>>;
     fn used_statics(&self) -> &RefCell<Vec<Self::Value>>;
     fn set_frame_pointer_elimination(&self, llfn: Self::Value);
diff --git a/src/librustc_data_structures/indexed_vec.rs b/src/librustc_data_structures/indexed_vec.rs
index 359b89f683d..c7f6e54c3d5 100644
--- a/src/librustc_data_structures/indexed_vec.rs
+++ b/src/librustc_data_structures/indexed_vec.rs
@@ -212,6 +212,11 @@ macro_rules! newtype_index {
             fn add_usize(&self, u: usize) -> Option<Self> {
                 Idx::index(*self).checked_add(u).map(Self::new)
             }
+
+            #[inline]
+            fn sub_usize(&self, u: usize) -> Option<Self> {
+                Idx::index(*self).checked_sub(u).map(Self::new)
+            }
         }
 
         impl From<$type> for u32 {
diff --git a/src/librustc_errors/emitter.rs b/src/librustc_errors/emitter.rs
index 890d2c5ce0b..e1112a15577 100644
--- a/src/librustc_errors/emitter.rs
+++ b/src/librustc_errors/emitter.rs
@@ -162,6 +162,7 @@ impl ColorConfig {
     }
 }
 
+/// Handles the writing of `HumanReadableErrorType::Default` and `HumanReadableErrorType::Short`
 pub struct EmitterWriter {
     dst: Destination,
     sm: Option<Lrc<SourceMapperDyn>>,
@@ -170,7 +171,8 @@ pub struct EmitterWriter {
     ui_testing: bool,
 }
 
-struct FileWithAnnotatedLines {
+#[derive(Debug)]
+pub struct FileWithAnnotatedLines {
     file: Lrc<SourceFile>,
     lines: Vec<Line>,
     multiline_depth: usize,
@@ -221,169 +223,6 @@ impl EmitterWriter {
         }
     }
 
-    fn preprocess_annotations(&mut self, msp: &MultiSpan) -> Vec<FileWithAnnotatedLines> {
-        fn add_annotation_to_file(file_vec: &mut Vec<FileWithAnnotatedLines>,
-                                  file: Lrc<SourceFile>,
-                                  line_index: usize,
-                                  ann: Annotation) {
-
-            for slot in file_vec.iter_mut() {
-                // Look through each of our files for the one we're adding to
-                if slot.file.name == file.name {
-                    // See if we already have a line for it
-                    for line_slot in &mut slot.lines {
-                        if line_slot.line_index == line_index {
-                            line_slot.annotations.push(ann);
-                            return;
-                        }
-                    }
-                    // We don't have a line yet, create one
-                    slot.lines.push(Line {
-                        line_index,
-                        annotations: vec![ann],
-                    });
-                    slot.lines.sort();
-                    return;
-                }
-            }
-            // This is the first time we're seeing the file
-            file_vec.push(FileWithAnnotatedLines {
-                file,
-                lines: vec![Line {
-                                line_index,
-                                annotations: vec![ann],
-                            }],
-                multiline_depth: 0,
-            });
-        }
-
-        let mut output = vec![];
-        let mut multiline_annotations = vec![];
-
-        if let Some(ref sm) = self.sm {
-            for span_label in msp.span_labels() {
-                if span_label.span.is_dummy() {
-                    continue;
-                }
-
-                let lo = sm.lookup_char_pos(span_label.span.lo());
-                let mut hi = sm.lookup_char_pos(span_label.span.hi());
-
-                // Watch out for "empty spans". If we get a span like 6..6, we
-                // want to just display a `^` at 6, so convert that to
-                // 6..7. This is degenerate input, but it's best to degrade
-                // gracefully -- and the parser likes to supply a span like
-                // that for EOF, in particular.
-
-                if lo.col_display == hi.col_display && lo.line == hi.line {
-                    hi.col_display += 1;
-                }
-
-                let ann_type = if lo.line != hi.line {
-                    let ml = MultilineAnnotation {
-                        depth: 1,
-                        line_start: lo.line,
-                        line_end: hi.line,
-                        start_col: lo.col_display,
-                        end_col: hi.col_display,
-                        is_primary: span_label.is_primary,
-                        label: span_label.label.clone(),
-                        overlaps_exactly: false,
-                    };
-                    multiline_annotations.push((lo.file.clone(), ml.clone()));
-                    AnnotationType::Multiline(ml)
-                } else {
-                    AnnotationType::Singleline
-                };
-                let ann = Annotation {
-                    start_col: lo.col_display,
-                    end_col: hi.col_display,
-                    is_primary: span_label.is_primary,
-                    label: span_label.label.clone(),
-                    annotation_type: ann_type,
-                };
-
-                if !ann.is_multiline() {
-                    add_annotation_to_file(&mut output, lo.file, lo.line, ann);
-                }
-            }
-        }
-
-        // Find overlapping multiline annotations, put them at different depths
-        multiline_annotations.sort_by_key(|&(_, ref ml)| (ml.line_start, ml.line_end));
-        for item in multiline_annotations.clone() {
-            let ann = item.1;
-            for item in multiline_annotations.iter_mut() {
-                let ref mut a = item.1;
-                // Move all other multiline annotations overlapping with this one
-                // one level to the right.
-                if !(ann.same_span(a)) &&
-                    num_overlap(ann.line_start, ann.line_end, a.line_start, a.line_end, true)
-                {
-                    a.increase_depth();
-                } else if ann.same_span(a) && &ann != a {
-                    a.overlaps_exactly = true;
-                } else {
-                    break;
-                }
-            }
-        }
-
-        let mut max_depth = 0;  // max overlapping multiline spans
-        for (file, ann) in multiline_annotations {
-            if ann.depth > max_depth {
-                max_depth = ann.depth;
-            }
-            let mut end_ann = ann.as_end();
-            if !ann.overlaps_exactly {
-                // avoid output like
-                //
-                //  |        foo(
-                //  |   _____^
-                //  |  |_____|
-                //  | ||         bar,
-                //  | ||     );
-                //  | ||      ^
-                //  | ||______|
-                //  |  |______foo
-                //  |         baz
-                //
-                // and instead get
-                //
-                //  |       foo(
-                //  |  _____^
-                //  | |         bar,
-                //  | |     );
-                //  | |      ^
-                //  | |      |
-                //  | |______foo
-                //  |        baz
-                add_annotation_to_file(&mut output, file.clone(), ann.line_start, ann.as_start());
-                // 4 is the minimum vertical length of a multiline span when presented: two lines
-                // of code and two lines of underline. This is not true for the special case where
-                // the beginning doesn't have an underline, but the current logic seems to be
-                // working correctly.
-                let middle = min(ann.line_start + 4, ann.line_end);
-                for line in ann.line_start + 1..middle {
-                    // Every `|` that joins the beginning of the span (`___^`) to the end (`|__^`).
-                    add_annotation_to_file(&mut output, file.clone(), line, ann.as_line());
-                }
-                if middle < ann.line_end - 1 {
-                    for line in ann.line_end - 1..ann.line_end {
-                        add_annotation_to_file(&mut output, file.clone(), line, ann.as_line());
-                    }
-                }
-            } else {
-                end_ann.annotation_type = AnnotationType::Singleline;
-            }
-            add_annotation_to_file(&mut output, file, ann.line_end, end_ann);
-        }
-        for file_vec in output.iter_mut() {
-            file_vec.multiline_depth = max_depth;
-        }
-        output
-    }
-
     fn render_source_line(&self,
                           buffer: &mut StyledBuffer,
                           file: Lrc<SourceFile>,
@@ -1093,9 +932,7 @@ impl EmitterWriter {
             }
         }
 
-        // Preprocess all the annotations so that they are grouped by file and by line number
-        // This helps us quickly iterate over the whole message (including secondary file spans)
-        let mut annotated_files = self.preprocess_annotations(msp);
+        let mut annotated_files = FileWithAnnotatedLines::collect_annotations(msp, &self.sm);
 
         // Make sure our primary file comes first
         let (primary_lo, sm) = if let (Some(sm), Some(ref primary_span)) =
@@ -1503,6 +1340,176 @@ impl EmitterWriter {
     }
 }
 
+impl FileWithAnnotatedLines {
+    /// Preprocess all the annotations so that they are grouped by file and by line number
+    /// This helps us quickly iterate over the whole message (including secondary file spans)
+    pub fn collect_annotations(
+        msp: &MultiSpan,
+        source_map: &Option<Lrc<SourceMapperDyn>>
+    ) -> Vec<FileWithAnnotatedLines> {
+        fn add_annotation_to_file(file_vec: &mut Vec<FileWithAnnotatedLines>,
+                                  file: Lrc<SourceFile>,
+                                  line_index: usize,
+                                  ann: Annotation) {
+
+            for slot in file_vec.iter_mut() {
+                // Look through each of our files for the one we're adding to
+                if slot.file.name == file.name {
+                    // See if we already have a line for it
+                    for line_slot in &mut slot.lines {
+                        if line_slot.line_index == line_index {
+                            line_slot.annotations.push(ann);
+                            return;
+                        }
+                    }
+                    // We don't have a line yet, create one
+                    slot.lines.push(Line {
+                        line_index,
+                        annotations: vec![ann],
+                    });
+                    slot.lines.sort();
+                    return;
+                }
+            }
+            // This is the first time we're seeing the file
+            file_vec.push(FileWithAnnotatedLines {
+                file,
+                lines: vec![Line {
+                                line_index,
+                                annotations: vec![ann],
+                            }],
+                multiline_depth: 0,
+            });
+        }
+
+        let mut output = vec![];
+        let mut multiline_annotations = vec![];
+
+        if let Some(ref sm) = source_map {
+            for span_label in msp.span_labels() {
+                if span_label.span.is_dummy() {
+                    continue;
+                }
+
+                let lo = sm.lookup_char_pos(span_label.span.lo());
+                let mut hi = sm.lookup_char_pos(span_label.span.hi());
+
+                // Watch out for "empty spans". If we get a span like 6..6, we
+                // want to just display a `^` at 6, so convert that to
+                // 6..7. This is degenerate input, but it's best to degrade
+                // gracefully -- and the parser likes to supply a span like
+                // that for EOF, in particular.
+
+                if lo.col_display == hi.col_display && lo.line == hi.line {
+                    hi.col_display += 1;
+                }
+
+                let ann_type = if lo.line != hi.line {
+                    let ml = MultilineAnnotation {
+                        depth: 1,
+                        line_start: lo.line,
+                        line_end: hi.line,
+                        start_col: lo.col_display,
+                        end_col: hi.col_display,
+                        is_primary: span_label.is_primary,
+                        label: span_label.label.clone(),
+                        overlaps_exactly: false,
+                    };
+                    multiline_annotations.push((lo.file.clone(), ml.clone()));
+                    AnnotationType::Multiline(ml)
+                } else {
+                    AnnotationType::Singleline
+                };
+                let ann = Annotation {
+                    start_col: lo.col_display,
+                    end_col: hi.col_display,
+                    is_primary: span_label.is_primary,
+                    label: span_label.label.clone(),
+                    annotation_type: ann_type,
+                };
+
+                if !ann.is_multiline() {
+                    add_annotation_to_file(&mut output, lo.file, lo.line, ann);
+                }
+            }
+        }
+
+        // Find overlapping multiline annotations, put them at different depths
+        multiline_annotations.sort_by_key(|&(_, ref ml)| (ml.line_start, ml.line_end));
+        for item in multiline_annotations.clone() {
+            let ann = item.1;
+            for item in multiline_annotations.iter_mut() {
+                let ref mut a = item.1;
+                // Move all other multiline annotations overlapping with this one
+                // one level to the right.
+                if !(ann.same_span(a)) &&
+                    num_overlap(ann.line_start, ann.line_end, a.line_start, a.line_end, true)
+                {
+                    a.increase_depth();
+                } else if ann.same_span(a) && &ann != a {
+                    a.overlaps_exactly = true;
+                } else {
+                    break;
+                }
+            }
+        }
+
+        let mut max_depth = 0;  // max overlapping multiline spans
+        for (file, ann) in multiline_annotations {
+            if ann.depth > max_depth {
+                max_depth = ann.depth;
+            }
+            let mut end_ann = ann.as_end();
+            if !ann.overlaps_exactly {
+                // avoid output like
+                //
+                //  |        foo(
+                //  |   _____^
+                //  |  |_____|
+                //  | ||         bar,
+                //  | ||     );
+                //  | ||      ^
+                //  | ||______|
+                //  |  |______foo
+                //  |         baz
+                //
+                // and instead get
+                //
+                //  |       foo(
+                //  |  _____^
+                //  | |         bar,
+                //  | |     );
+                //  | |      ^
+                //  | |      |
+                //  | |______foo
+                //  |        baz
+                add_annotation_to_file(&mut output, file.clone(), ann.line_start, ann.as_start());
+                // 4 is the minimum vertical length of a multiline span when presented: two lines
+                // of code and two lines of underline. This is not true for the special case where
+                // the beginning doesn't have an underline, but the current logic seems to be
+                // working correctly.
+                let middle = min(ann.line_start + 4, ann.line_end);
+                for line in ann.line_start + 1..middle {
+                    // Every `|` that joins the beginning of the span (`___^`) to the end (`|__^`).
+                    add_annotation_to_file(&mut output, file.clone(), line, ann.as_line());
+                }
+                if middle < ann.line_end - 1 {
+                    for line in ann.line_end - 1..ann.line_end {
+                        add_annotation_to_file(&mut output, file.clone(), line, ann.as_line());
+                    }
+                }
+            } else {
+                end_ann.annotation_type = AnnotationType::Singleline;
+            }
+            add_annotation_to_file(&mut output, file, ann.line_end, end_ann);
+        }
+        for file_vec in output.iter_mut() {
+            file_vec.multiline_depth = max_depth;
+        }
+        output
+    }
+}
+
 fn draw_col_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
     buffer.puts(line, col, "| ", Style::LineNumber);
 }
diff --git a/src/librustc_mir/borrow_check/conflict_errors.rs b/src/librustc_mir/borrow_check/conflict_errors.rs
index 8022d1f0c73..f464e58e36b 100644
--- a/src/librustc_mir/borrow_check/conflict_errors.rs
+++ b/src/librustc_mir/borrow_check/conflict_errors.rs
@@ -1616,7 +1616,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
                             );
 
                             // Find the local from the operand.
-                            let assigned_from_local = match assigned_from.local() {
+                            let assigned_from_local = match assigned_from.local_or_deref_local() {
                                 Some(local) => local,
                                 None => continue,
                             };
@@ -1672,7 +1672,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
                     );
 
                     // Find the local from the rvalue.
-                    let assigned_from_local = match assigned_from.local() {
+                    let assigned_from_local = match assigned_from.local_or_deref_local() {
                         Some(local) => local,
                         None => continue,
                     };
@@ -1735,7 +1735,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
                         assigned_from,
                     );
 
-                    if let Some(assigned_from_local) = assigned_from.local() {
+                    if let Some(assigned_from_local) = assigned_from.local_or_deref_local() {
                         debug!(
                             "annotate_argument_and_return_for_borrow: assigned_from_local={:?}",
                             assigned_from_local,
diff --git a/src/librustc_mir/borrow_check/error_reporting.rs b/src/librustc_mir/borrow_check/error_reporting.rs
index ec0359794e7..5a22c81a5d0 100644
--- a/src/librustc_mir/borrow_check/error_reporting.rs
+++ b/src/librustc_mir/borrow_check/error_reporting.rs
@@ -37,15 +37,15 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
         diag: &mut DiagnosticBuilder<'_>,
     ) {
         debug!("add_moved_or_invoked_closure_note: location={:?} place={:?}", location, place);
-        let mut target = place.local();
+        let mut target = place.local_or_deref_local();
         for stmt in &self.mir[location.block].statements[location.statement_index..] {
             debug!("add_moved_or_invoked_closure_note: stmt={:?} target={:?}", stmt, target);
             if let StatementKind::Assign(into, box Rvalue::Use(from)) = &stmt.kind {
                 debug!("add_fnonce_closure_note: into={:?} from={:?}", into, from);
                 match from {
                     Operand::Copy(ref place) |
-                    Operand::Move(ref place) if target == place.local() =>
-                        target = into.local(),
+                    Operand::Move(ref place) if target == place.local_or_deref_local() =>
+                        target = into.local_or_deref_local(),
                     _ => {},
                 }
             }
@@ -69,8 +69,8 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
             if self.infcx.tcx.parent(id) == self.infcx.tcx.lang_items().fn_once_trait() {
                 let closure = match args.first() {
                     Some(Operand::Copy(ref place)) |
-                    Some(Operand::Move(ref place)) if target == place.local() =>
-                        place.local().unwrap(),
+                    Some(Operand::Move(ref place)) if target == place.local_or_deref_local() =>
+                        place.local_or_deref_local().unwrap(),
                     _ => return,
                 };
 
diff --git a/src/librustc_mir/build/expr/as_rvalue.rs b/src/librustc_mir/build/expr/as_rvalue.rs
index 07a9f294fb6..685db7713ca 100644
--- a/src/librustc_mir/build/expr/as_rvalue.rs
+++ b/src/librustc_mir/build/expr/as_rvalue.rs
@@ -528,7 +528,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
             }) => {
                 // Not projected from the implicit `self` in a closure.
                 debug_assert!(
-                    match base.local() {
+                    match base.local_or_deref_local() {
                         Some(local) => local == Local::new(1),
                         None => false,
                     },
diff --git a/src/librustc_mir/dataflow/impls/storage_liveness.rs b/src/librustc_mir/dataflow/impls/storage_liveness.rs
index ab79d6cc947..0fb66032a17 100644
--- a/src/librustc_mir/dataflow/impls/storage_liveness.rs
+++ b/src/librustc_mir/dataflow/impls/storage_liveness.rs
@@ -46,8 +46,10 @@ impl<'a, 'tcx> BitDenotation<'tcx> for MaybeStorageLive<'a, 'tcx> {
                          sets: &mut BlockSets<'_, Local>,
                          loc: Location) {
         match &self.mir[loc.block].terminator().kind {
-            TerminatorKind::Drop { location, .. } => if let Some(l) = location.local() {
-                sets.kill(l);
+            TerminatorKind::Drop { location, .. } => {
+                if let Some(l) = location.local_or_deref_local() {
+                    sets.kill(l);
+                }
             }
             _ => (),
         }
diff --git a/src/librustc_privacy/lib.rs b/src/librustc_privacy/lib.rs
index 68930533a28..a08c028390b 100644
--- a/src/librustc_privacy/lib.rs
+++ b/src/librustc_privacy/lib.rs
@@ -1703,8 +1703,13 @@ impl<'a, 'tcx> PrivateItemsInPublicInterfacesVisitor<'a, 'tcx> {
         }
     }
 
-    fn check_trait_or_impl_item(&self, hir_id: hir::HirId, assoc_item_kind: AssocItemKind,
-                                defaultness: hir::Defaultness, vis: ty::Visibility) {
+    fn check_assoc_item(
+        &self,
+        hir_id: hir::HirId,
+        assoc_item_kind: AssocItemKind,
+        defaultness: hir::Defaultness,
+        vis: ty::Visibility,
+    ) {
         let mut check = self.check(hir_id, vis);
 
         let (check_ty, is_assoc_ty) = match assoc_item_kind {
@@ -1754,8 +1759,12 @@ impl<'a, 'tcx> Visitor<'tcx> for PrivateItemsInPublicInterfacesVisitor<'a, 'tcx>
                 self.check(item.hir_id, item_visibility).generics().predicates();
 
                 for trait_item_ref in trait_item_refs {
-                    self.check_trait_or_impl_item(trait_item_ref.id.hir_id, trait_item_ref.kind,
-                                                  trait_item_ref.defaultness, item_visibility);
+                    self.check_assoc_item(
+                        trait_item_ref.id.hir_id,
+                        trait_item_ref.kind,
+                        trait_item_ref.defaultness,
+                        item_visibility,
+                    );
                 }
             }
             hir::ItemKind::TraitAlias(..) => {
@@ -1803,8 +1812,12 @@ impl<'a, 'tcx> Visitor<'tcx> for PrivateItemsInPublicInterfacesVisitor<'a, 'tcx>
                     } else {
                         impl_vis
                     };
-                    self.check_trait_or_impl_item(impl_item_ref.id.hir_id, impl_item_ref.kind,
-                                                  impl_item_ref.defaultness, impl_item_vis);
+                    self.check_assoc_item(
+                        impl_item_ref.id.hir_id,
+                        impl_item_ref.kind,
+                        impl_item_ref.defaultness,
+                        impl_item_vis,
+                    );
                 }
             }
         }
diff --git a/src/librustc_resolve/lib.rs b/src/librustc_resolve/lib.rs
index c05b69ab44f..9b7b44025c1 100644
--- a/src/librustc_resolve/lib.rs
+++ b/src/librustc_resolve/lib.rs
@@ -860,7 +860,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Resolver<'a> {
             FnKind::ItemFn(_, ref header, ..) =>
                 (FnItemRibKind, &header.asyncness.node),
             FnKind::Method(_, ref sig, _, _) =>
-                (TraitOrImplItemRibKind, &sig.header.asyncness.node),
+                (AssocItemRibKind, &sig.header.asyncness.node),
             FnKind::Closure(_) =>
                 // Async closures aren't resolved through `visit_fn`-- they're
                 // processed separately
@@ -1033,7 +1033,7 @@ enum RibKind<'a> {
     /// methods or associated types. Allow references to ty params that impl or trait
     /// binds. Disallow any other upvars (including other ty params that are
     /// upvars).
-    TraitOrImplItemRibKind,
+    AssocItemRibKind,
 
     /// We passed through a function definition. Disallow upvars.
     /// Permit only those const parameters that are specified in the function's generics.
@@ -2612,7 +2612,7 @@ impl<'a> Resolver<'a> {
 
                         for trait_item in trait_items {
                             let generic_params = HasGenericParams(&trait_item.generics,
-                                                                    TraitOrImplItemRibKind);
+                                                                    AssocItemRibKind);
                             this.with_generic_param_rib(generic_params, |this| {
                                 match trait_item.node {
                                     TraitItemKind::Const(ref ty, ref default) => {
@@ -2899,7 +2899,7 @@ impl<'a> Resolver<'a> {
 
                                     // We also need a new scope for the impl item type parameters.
                                     let generic_params = HasGenericParams(&impl_item.generics,
-                                                                          TraitOrImplItemRibKind);
+                                                                          AssocItemRibKind);
                                     this.with_generic_param_rib(generic_params, |this| {
                                         use self::ResolutionError::*;
                                         match impl_item.node {
@@ -4074,7 +4074,7 @@ impl<'a> Resolver<'a> {
                                 seen.insert(node_id, depth);
                             }
                         }
-                        ItemRibKind | FnItemRibKind | TraitOrImplItemRibKind => {
+                        ItemRibKind | FnItemRibKind | AssocItemRibKind => {
                             // This was an attempt to access an upvar inside a
                             // named function item. This is not allowed, so we
                             // report an error.
@@ -4103,7 +4103,7 @@ impl<'a> Resolver<'a> {
             Res::Def(DefKind::TyParam, _) | Res::SelfTy(..) => {
                 for rib in ribs {
                     match rib.kind {
-                        NormalRibKind | TraitOrImplItemRibKind | ClosureRibKind(..) |
+                        NormalRibKind | AssocItemRibKind | ClosureRibKind(..) |
                         ModuleRibKind(..) | MacroDefinition(..) | ForwardTyParamBanRibKind |
                         ConstantItemRibKind | TyParamAsConstParamTy => {
                             // Nothing to do. Continue.
diff --git a/src/libstd/io/buffered.rs b/src/libstd/io/buffered.rs
index d0e56acc8fb..aaf628e6c26 100644
--- a/src/libstd/io/buffered.rs
+++ b/src/libstd/io/buffered.rs
@@ -158,7 +158,6 @@ impl<R> BufReader<R> {
     /// # Examples
     ///
     /// ```no_run
-    /// # #![feature(bufreader_buffer)]
     /// use std::io::{BufReader, BufRead};
     /// use std::fs::File;
     ///
@@ -173,7 +172,7 @@ impl<R> BufReader<R> {
     ///     Ok(())
     /// }
     /// ```
-    #[unstable(feature = "bufreader_buffer", issue = "45323")]
+    #[stable(feature = "bufreader_buffer", since = "1.37.0")]
     pub fn buffer(&self) -> &[u8] {
         &self.buf[self.pos..self.cap]
     }
@@ -552,7 +551,6 @@ impl<W: Write> BufWriter<W> {
     /// # Examples
     ///
     /// ```no_run
-    /// # #![feature(bufreader_buffer)]
     /// use std::io::BufWriter;
     /// use std::net::TcpStream;
     ///
@@ -561,7 +559,7 @@ impl<W: Write> BufWriter<W> {
     /// // See how many bytes are currently buffered
     /// let bytes_buffered = buf_writer.buffer().len();
     /// ```
-    #[unstable(feature = "bufreader_buffer", issue = "45323")]
+    #[stable(feature = "bufreader_buffer", since = "1.37.0")]
     pub fn buffer(&self) -> &[u8] {
         &self.buf
     }
diff --git a/src/test/run-pass/impl-trait/example-calendar.rs b/src/test/run-pass/impl-trait/example-calendar.rs
index 968e9b7d34a..f1b1656745e 100644
--- a/src/test/run-pass/impl-trait/example-calendar.rs
+++ b/src/test/run-pass/impl-trait/example-calendar.rs
@@ -180,6 +180,10 @@ impl std::iter::Step for NaiveDate {
     fn add_usize(&self, _: usize) -> Option<Self> {
         unimplemented!()
     }
+
+    fn sub_usize(&self, _: usize) -> Option<Self> {
+        unimplemented!()
+    }
 }
 
 #[derive(Copy, Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]