Update prebuilt Clang to r353983e.HEADq10.0

clang 9.0.5 (based on r353983e) from build 5696680.

Bug: http://b/135931688
Bug: http://b/136008926
Test: N/A
Change-Id: I922d17410047d2e2df4625615352c588ee71b203

1 files changed, 945 insertions, 0 deletions

diff --git a/clang-r353983e/include/llvm/ADT/BitVector.h b/clang-r353983e/include/llvm/ADT/BitVector.h
new file mode 100644
index 00000000..fabf5d9c
--- /dev/null
+++ b/clang-r353983e/include/llvm/ADT/BitVector.h
@@ -0,0 +1,945 @@
+//===- llvm/ADT/BitVector.h - Bit vectors -----------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the BitVector class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_BITVECTOR_H
+#define LLVM_ADT_BITVECTOR_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/Support/MathExtras.h"
+#include <algorithm>
+#include <cassert>
+#include <climits>
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+#include <utility>
+
+namespace llvm {
+
+/// ForwardIterator for the bits that are set.
+/// Iterators get invalidated when resize / reserve is called.
+template <typename BitVectorT> class const_set_bits_iterator_impl {
+  const BitVectorT &Parent;
+  int Current = 0;
+
+  void advance() {
+    assert(Current != -1 && "Trying to advance past end.");
+    Current = Parent.find_next(Current);
+  }
+
+public:
+  const_set_bits_iterator_impl(const BitVectorT &Parent, int Current)
+      : Parent(Parent), Current(Current) {}
+  explicit const_set_bits_iterator_impl(const BitVectorT &Parent)
+      : const_set_bits_iterator_impl(Parent, Parent.find_first()) {}
+  const_set_bits_iterator_impl(const const_set_bits_iterator_impl &) = default;
+
+  const_set_bits_iterator_impl operator++(int) {
+    auto Prev = *this;
+    advance();
+    return Prev;
+  }
+
+  const_set_bits_iterator_impl &operator++() {
+    advance();
+    return *this;
+  }
+
+  unsigned operator*() const { return Current; }
+
+  bool operator==(const const_set_bits_iterator_impl &Other) const {
+    assert(&Parent == &Other.Parent &&
+           "Comparing iterators from different BitVectors");
+    return Current == Other.Current;
+  }
+
+  bool operator!=(const const_set_bits_iterator_impl &Other) const {
+    assert(&Parent == &Other.Parent &&
+           "Comparing iterators from different BitVectors");
+    return Current != Other.Current;
+  }
+};
+
+class BitVector {
+  typedef unsigned long BitWord;
+
+  enum { BITWORD_SIZE = (unsigned)sizeof(BitWord) * CHAR_BIT };
+
+  static_assert(BITWORD_SIZE == 64 || BITWORD_SIZE == 32,
+                "Unsupported word size");
+
+  MutableArrayRef<BitWord> Bits; // Actual bits.
+  unsigned Size;                 // Size of bitvector in bits.
+
+public:
+  typedef unsigned size_type;
+  // Encapsulation of a single bit.
+  class reference {
+    friend class BitVector;
+
+    BitWord *WordRef;
+    unsigned BitPos;
+
+  public:
+    reference(BitVector &b, unsigned Idx) {
+      WordRef = &b.Bits[Idx / BITWORD_SIZE];
+      BitPos = Idx % BITWORD_SIZE;
+    }
+
+    reference() = delete;
+    reference(const reference&) = default;
+
+    reference &operator=(reference t) {
+      *this = bool(t);
+      return *this;
+    }
+
+    reference& operator=(bool t) {
+      if (t)
+        *WordRef |= BitWord(1) << BitPos;
+      else
+        *WordRef &= ~(BitWord(1) << BitPos);
+      return *this;
+    }
+
+    operator bool() const {
+      return ((*WordRef) & (BitWord(1) << BitPos)) != 0;
+    }
+  };
+
+  typedef const_set_bits_iterator_impl<BitVector> const_set_bits_iterator;
+  typedef const_set_bits_iterator set_iterator;
+
+  const_set_bits_iterator set_bits_begin() const {
+    return const_set_bits_iterator(*this);
+  }
+  const_set_bits_iterator set_bits_end() const {
+    return const_set_bits_iterator(*this, -1);
+  }
+  iterator_range<const_set_bits_iterator> set_bits() const {
+    return make_range(set_bits_begin(), set_bits_end());
+  }
+
+  /// BitVector default ctor - Creates an empty bitvector.
+  BitVector() : Size(0) {}
+
+  /// BitVector ctor - Creates a bitvector of specified number of bits. All
+  /// bits are initialized to the specified value.
+  explicit BitVector(unsigned s, bool t = false) : Size(s) {
+    size_t Capacity = NumBitWords(s);
+    Bits = allocate(Capacity);
+    init_words(Bits, t);
+    if (t)
+      clear_unused_bits();
+  }
+
+  /// BitVector copy ctor.
+  BitVector(const BitVector &RHS) : Size(RHS.size()) {
+    if (Size == 0) {
+      Bits = MutableArrayRef<BitWord>();
+      return;
+    }
+
+    size_t Capacity = NumBitWords(RHS.size());
+    Bits = allocate(Capacity);
+    std::memcpy(Bits.data(), RHS.Bits.data(), Capacity * sizeof(BitWord));
+  }
+
+  BitVector(BitVector &&RHS) : Bits(RHS.Bits), Size(RHS.Size) {
+    RHS.Bits = MutableArrayRef<BitWord>();
+    RHS.Size = 0;
+  }
+
+  ~BitVector() { std::free(Bits.data()); }
+
+  /// empty - Tests whether there are no bits in this bitvector.
+  bool empty() const { return Size == 0; }
+
+  /// size - Returns the number of bits in this bitvector.
+  size_type size() const { return Size; }
+
+  /// count - Returns the number of bits which are set.
+  size_type count() const {
+    unsigned NumBits = 0;
+    for (unsigned i = 0; i < NumBitWords(size()); ++i)
+      NumBits += countPopulation(Bits[i]);
+    return NumBits;
+  }
+
+  /// any - Returns true if any bit is set.
+  bool any() const {
+    for (unsigned i = 0; i < NumBitWords(size()); ++i)
+      if (Bits[i] != 0)
+        return true;
+    return false;
+  }
+
+  /// all - Returns true if all bits are set.
+  bool all() const {
+    for (unsigned i = 0; i < Size / BITWORD_SIZE; ++i)
+      if (Bits[i] != ~0UL)
+        return false;
+
+    // If bits remain check that they are ones. The unused bits are always zero.
+    if (unsigned Remainder = Size % BITWORD_SIZE)
+      return Bits[Size / BITWORD_SIZE] == (1UL << Remainder) - 1;
+
+    return true;
+  }
+
+  /// none - Returns true if none of the bits are set.
+  bool none() const {
+    return !any();
+  }
+
+  /// find_first_in - Returns the index of the first set bit in the range
+  /// [Begin, End).  Returns -1 if all bits in the range are unset.
+  int find_first_in(unsigned Begin, unsigned End) const {
+    assert(Begin <= End && End <= Size);
+    if (Begin == End)
+      return -1;
+
+    unsigned FirstWord = Begin / BITWORD_SIZE;
+    unsigned LastWord = (End - 1) / BITWORD_SIZE;
+
+    // Check subsequent words.
+    for (unsigned i = FirstWord; i <= LastWord; ++i) {
+      BitWord Copy = Bits[i];
+
+      if (i == FirstWord) {
+        unsigned FirstBit = Begin % BITWORD_SIZE;
+        Copy &= maskTrailingZeros<BitWord>(FirstBit);
+      }
+
+      if (i == LastWord) {
+        unsigned LastBit = (End - 1) % BITWORD_SIZE;
+        Copy &= maskTrailingOnes<BitWord>(LastBit + 1);
+      }
+      if (Copy != 0)
+        return i * BITWORD_SIZE + countTrailingZeros(Copy);
+    }
+    return -1;
+  }
+
+  /// find_last_in - Returns the index of the last set bit in the range
+  /// [Begin, End).  Returns -1 if all bits in the range are unset.
+  int find_last_in(unsigned Begin, unsigned End) const {
+    assert(Begin <= End && End <= Size);
+    if (Begin == End)
+      return -1;
+
+    unsigned LastWord = (End - 1) / BITWORD_SIZE;
+    unsigned FirstWord = Begin / BITWORD_SIZE;
+
+    for (unsigned i = LastWord + 1; i >= FirstWord + 1; --i) {
+      unsigned CurrentWord = i - 1;
+
+      BitWord Copy = Bits[CurrentWord];
+      if (CurrentWord == LastWord) {
+        unsigned LastBit = (End - 1) % BITWORD_SIZE;
+        Copy &= maskTrailingOnes<BitWord>(LastBit + 1);
+      }
+
+      if (CurrentWord == FirstWord) {
+        unsigned FirstBit = Begin % BITWORD_SIZE;
+        Copy &= maskTrailingZeros<BitWord>(FirstBit);
+      }
+
+      if (Copy != 0)
+        return (CurrentWord + 1) * BITWORD_SIZE - countLeadingZeros(Copy) - 1;
+    }
+
+    return -1;
+  }
+
+  /// find_first_unset_in - Returns the index of the first unset bit in the
+  /// range [Begin, End).  Returns -1 if all bits in the range are set.
+  int find_first_unset_in(unsigned Begin, unsigned End) const {
+    assert(Begin <= End && End <= Size);
+    if (Begin == End)
+      return -1;
+
+    unsigned FirstWord = Begin / BITWORD_SIZE;
+    unsigned LastWord = (End - 1) / BITWORD_SIZE;
+
+    // Check subsequent words.
+    for (unsigned i = FirstWord; i <= LastWord; ++i) {
+      BitWord Copy = Bits[i];
+
+      if (i == FirstWord) {
+        unsigned FirstBit = Begin % BITWORD_SIZE;
+        Copy |= maskTrailingOnes<BitWord>(FirstBit);
+      }
+
+      if (i == LastWord) {
+        unsigned LastBit = (End - 1) % BITWORD_SIZE;
+        Copy |= maskTrailingZeros<BitWord>(LastBit + 1);
+      }
+      if (Copy != ~0UL) {
+        unsigned Result = i * BITWORD_SIZE + countTrailingOnes(Copy);
+        return Result < size() ? Result : -1;
+      }
+    }
+    return -1;
+  }
+
+  /// find_last_unset_in - Returns the index of the last unset bit in the
+  /// range [Begin, End).  Returns -1 if all bits in the range are set.
+  int find_last_unset_in(unsigned Begin, unsigned End) const {
+    assert(Begin <= End && End <= Size);
+    if (Begin == End)
+      return -1;
+
+    unsigned LastWord = (End - 1) / BITWORD_SIZE;
+    unsigned FirstWord = Begin / BITWORD_SIZE;
+
+    for (unsigned i = LastWord + 1; i >= FirstWord + 1; --i) {
+      unsigned CurrentWord = i - 1;
+
+      BitWord Copy = Bits[CurrentWord];
+      if (CurrentWord == LastWord) {
+        unsigned LastBit = (End - 1) % BITWORD_SIZE;
+        Copy |= maskTrailingZeros<BitWord>(LastBit + 1);
+      }
+
+      if (CurrentWord == FirstWord) {
+        unsigned FirstBit = Begin % BITWORD_SIZE;
+        Copy |= maskTrailingOnes<BitWord>(FirstBit);
+      }
+
+      if (Copy != ~0UL) {
+        unsigned Result =
+            (CurrentWord + 1) * BITWORD_SIZE - countLeadingOnes(Copy) - 1;
+        return Result < Size ? Result : -1;
+      }
+    }
+    return -1;
+  }
+
+  /// find_first - Returns the index of the first set bit, -1 if none
+  /// of the bits are set.
+  int find_first() const { return find_first_in(0, Size); }
+
+  /// find_last - Returns the index of the last set bit, -1 if none of the bits
+  /// are set.
+  int find_last() const { return find_last_in(0, Size); }
+
+  /// find_next - Returns the index of the next set bit following the
+  /// "Prev" bit. Returns -1 if the next set bit is not found.
+  int find_next(unsigned Prev) const { return find_first_in(Prev + 1, Size); }
+
+  /// find_prev - Returns the index of the first set bit that precedes the
+  /// the bit at \p PriorTo.  Returns -1 if all previous bits are unset.
+  int find_prev(unsigned PriorTo) const { return find_last_in(0, PriorTo); }
+
+  /// find_first_unset - Returns the index of the first unset bit, -1 if all
+  /// of the bits are set.
+  int find_first_unset() const { return find_first_unset_in(0, Size); }
+
+  /// find_next_unset - Returns the index of the next unset bit following the
+  /// "Prev" bit.  Returns -1 if all remaining bits are set.
+  int find_next_unset(unsigned Prev) const {
+    return find_first_unset_in(Prev + 1, Size);
+  }
+
+  /// find_last_unset - Returns the index of the last unset bit, -1 if all of
+  /// the bits are set.
+  int find_last_unset() const { return find_last_unset_in(0, Size); }
+
+  /// find_prev_unset - Returns the index of the first unset bit that precedes
+  /// the bit at \p PriorTo.  Returns -1 if all previous bits are set.
+  int find_prev_unset(unsigned PriorTo) {
+    return find_last_unset_in(0, PriorTo);
+  }
+
+  /// clear - Removes all bits from the bitvector. Does not change capacity.
+  void clear() {
+    Size = 0;
+  }
+
+  /// resize - Grow or shrink the bitvector.
+  void resize(unsigned N, bool t = false) {
+    if (N > getBitCapacity()) {
+      unsigned OldCapacity = Bits.size();
+      grow(N);
+      init_words(Bits.drop_front(OldCapacity), t);
+    }
+
+    // Set any old unused bits that are now included in the BitVector. This
+    // may set bits that are not included in the new vector, but we will clear
+    // them back out below.
+    if (N > Size)
+      set_unused_bits(t);
+
+    // Update the size, and clear out any bits that are now unused
+    unsigned OldSize = Size;
+    Size = N;
+    if (t || N < OldSize)
+      clear_unused_bits();
+  }
+
+  void reserve(unsigned N) {
+    if (N > getBitCapacity())
+      grow(N);
+  }
+
+  // Set, reset, flip
+  BitVector &set() {
+    init_words(Bits, true);
+    clear_unused_bits();
+    return *this;
+  }
+
+  BitVector &set(unsigned Idx) {
+    assert(Bits.data() && "Bits never allocated");
+    Bits[Idx / BITWORD_SIZE] |= BitWord(1) << (Idx % BITWORD_SIZE);
+    return *this;
+  }
+
+  /// set - Efficiently set a range of bits in [I, E)
+  BitVector &set(unsigned I, unsigned E) {
+    assert(I <= E && "Attempted to set backwards range!");
+    assert(E <= size() && "Attempted to set out-of-bounds range!");
+
+    if (I == E) return *this;
+
+    if (I / BITWORD_SIZE == E / BITWORD_SIZE) {
+      BitWord EMask = 1UL << (E % BITWORD_SIZE);
+      BitWord IMask = 1UL << (I % BITWORD_SIZE);
+      BitWord Mask = EMask - IMask;
+      Bits[I / BITWORD_SIZE] |= Mask;
+      return *this;
+    }
+
+    BitWord PrefixMask = ~0UL << (I % BITWORD_SIZE);
+    Bits[I / BITWORD_SIZE] |= PrefixMask;
+    I = alignTo(I, BITWORD_SIZE);
+
+    for (; I + BITWORD_SIZE <= E; I += BITWORD_SIZE)
+      Bits[I / BITWORD_SIZE] = ~0UL;
+
+    BitWord PostfixMask = (1UL << (E % BITWORD_SIZE)) - 1;
+    if (I < E)
+      Bits[I / BITWORD_SIZE] |= PostfixMask;
+
+    return *this;
+  }
+
+  BitVector &reset() {
+    init_words(Bits, false);
+    return *this;
+  }
+
+  BitVector &reset(unsigned Idx) {
+    Bits[Idx / BITWORD_SIZE] &= ~(BitWord(1) << (Idx % BITWORD_SIZE));
+    return *this;
+  }
+
+  /// reset - Efficiently reset a range of bits in [I, E)
+  BitVector &reset(unsigned I, unsigned E) {
+    assert(I <= E && "Attempted to reset backwards range!");
+    assert(E <= size() && "Attempted to reset out-of-bounds range!");
+
+    if (I == E) return *this;
+
+    if (I / BITWORD_SIZE == E / BITWORD_SIZE) {
+      BitWord EMask = 1UL << (E % BITWORD_SIZE);
+      BitWord IMask = 1UL << (I % BITWORD_SIZE);
+      BitWord Mask = EMask - IMask;
+      Bits[I / BITWORD_SIZE] &= ~Mask;
+      return *this;
+    }
+
+    BitWord PrefixMask = ~0UL << (I % BITWORD_SIZE);
+    Bits[I / BITWORD_SIZE] &= ~PrefixMask;
+    I = alignTo(I, BITWORD_SIZE);
+
+    for (; I + BITWORD_SIZE <= E; I += BITWORD_SIZE)
+      Bits[I / BITWORD_SIZE] = 0UL;
+
+    BitWord PostfixMask = (1UL << (E % BITWORD_SIZE)) - 1;
+    if (I < E)
+      Bits[I / BITWORD_SIZE] &= ~PostfixMask;
+
+    return *this;
+  }
+
+  BitVector &flip() {
+    for (unsigned i = 0; i < NumBitWords(size()); ++i)
+      Bits[i] = ~Bits[i];
+    clear_unused_bits();
+    return *this;
+  }
+
+  BitVector &flip(unsigned Idx) {
+    Bits[Idx / BITWORD_SIZE] ^= BitWord(1) << (Idx % BITWORD_SIZE);
+    return *this;
+  }
+
+  // Indexing.
+  reference operator[](unsigned Idx) {
+    assert (Idx < Size && "Out-of-bounds Bit access.");
+    return reference(*this, Idx);
+  }
+
+  bool operator[](unsigned Idx) const {
+    assert (Idx < Size && "Out-of-bounds Bit access.");
+    BitWord Mask = BitWord(1) << (Idx % BITWORD_SIZE);
+    return (Bits[Idx / BITWORD_SIZE] & Mask) != 0;
+  }
+
+  bool test(unsigned Idx) const {
+    return (*this)[Idx];
+  }
+
+  // Push single bit to end of vector.
+  void push_back(bool Val) {
+    unsigned OldSize = Size;
+    unsigned NewSize = Size + 1;
+
+    // Resize, which will insert zeros.
+    // If we already fit then the unused bits will be already zero.
+    if (NewSize > getBitCapacity())
+      resize(NewSize, false);
+    else
+      Size = NewSize;
+
+    // If true, set single bit.
+    if (Val)
+      set(OldSize);
+  }
+
+  /// Test if any common bits are set.
+  bool anyCommon(const BitVector &RHS) const {
+    unsigned ThisWords = NumBitWords(size());
+    unsigned RHSWords  = NumBitWords(RHS.size());
+    for (unsigned i = 0, e = std::min(ThisWords, RHSWords); i != e; ++i)
+      if (Bits[i] & RHS.Bits[i])
+        return true;
+    return false;
+  }
+
+  // Comparison operators.
+  bool operator==(const BitVector &RHS) const {
+    unsigned ThisWords = NumBitWords(size());
+    unsigned RHSWords  = NumBitWords(RHS.size());
+    unsigned i;
+    for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
+      if (Bits[i] != RHS.Bits[i])
+        return false;
+
+    // Verify that any extra words are all zeros.
+    if (i != ThisWords) {
+      for (; i != ThisWords; ++i)
+        if (Bits[i])
+          return false;
+    } else if (i != RHSWords) {
+      for (; i != RHSWords; ++i)
+        if (RHS.Bits[i])
+          return false;
+    }
+    return true;
+  }
+
+  bool operator!=(const BitVector &RHS) const {
+    return !(*this == RHS);
+  }
+
+  /// Intersection, union, disjoint union.
+  BitVector &operator&=(const BitVector &RHS) {
+    unsigned ThisWords = NumBitWords(size());
+    unsigned RHSWords  = NumBitWords(RHS.size());
+    unsigned i;
+    for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
+      Bits[i] &= RHS.Bits[i];
+
+    // Any bits that are just in this bitvector become zero, because they aren't
+    // in the RHS bit vector.  Any words only in RHS are ignored because they
+    // are already zero in the LHS.
+    for (; i != ThisWords; ++i)
+      Bits[i] = 0;
+
+    return *this;
+  }
+
+  /// reset - Reset bits that are set in RHS. Same as *this &= ~RHS.
+  BitVector &reset(const BitVector &RHS) {
+    unsigned ThisWords = NumBitWords(size());
+    unsigned RHSWords  = NumBitWords(RHS.size());
+    unsigned i;
+    for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
+      Bits[i] &= ~RHS.Bits[i];
+    return *this;
+  }
+
+  /// test - Check if (This - RHS) is zero.
+  /// This is the same as reset(RHS) and any().
+  bool test(const BitVector &RHS) const {
+    unsigned ThisWords = NumBitWords(size());
+    unsigned RHSWords  = NumBitWords(RHS.size());
+    unsigned i;
+    for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
+      if ((Bits[i] & ~RHS.Bits[i]) != 0)
+        return true;
+
+    for (; i != ThisWords ; ++i)
+      if (Bits[i] != 0)
+        return true;
+
+    return false;
+  }
+
+  BitVector &operator|=(const BitVector &RHS) {
+    if (size() < RHS.size())
+      resize(RHS.size());
+    for (size_t i = 0, e = NumBitWords(RHS.size()); i != e; ++i)
+      Bits[i] |= RHS.Bits[i];
+    return *this;
+  }
+
+  BitVector &operator^=(const BitVector &RHS) {
+    if (size() < RHS.size())
+      resize(RHS.size());
+    for (size_t i = 0, e = NumBitWords(RHS.size()); i != e; ++i)
+      Bits[i] ^= RHS.Bits[i];
+    return *this;
+  }
+
+  BitVector &operator>>=(unsigned N) {
+    assert(N <= Size);
+    if (LLVM_UNLIKELY(empty() || N == 0))
+      return *this;
+
+    unsigned NumWords = NumBitWords(Size);
+    assert(NumWords >= 1);
+
+    wordShr(N / BITWORD_SIZE);
+
+    unsigned BitDistance = N % BITWORD_SIZE;
+    if (BitDistance == 0)
+      return *this;
+
+    // When the shift size is not a multiple of the word size, then we have
+    // a tricky situation where each word in succession needs to extract some
+    // of the bits from the next word and or them into this word while
+    // shifting this word to make room for the new bits.  This has to be done
+    // for every word in the array.
+
+    // Since we're shifting each word right, some bits will fall off the end
+    // of each word to the right, and empty space will be created on the left.
+    // The final word in the array will lose bits permanently, so starting at
+    // the beginning, work forwards shifting each word to the right, and
+    // OR'ing in the bits from the end of the next word to the beginning of
+    // the current word.
+
+    // Example:
+    //   Starting with {0xAABBCCDD, 0xEEFF0011, 0x22334455} and shifting right
+    //   by 4 bits.
+    // Step 1: Word[0] >>= 4           ; 0x0ABBCCDD
+    // Step 2: Word[0] |= 0x10000000   ; 0x1ABBCCDD
+    // Step 3: Word[1] >>= 4           ; 0x0EEFF001
+    // Step 4: Word[1] |= 0x50000000   ; 0x5EEFF001
+    // Step 5: Word[2] >>= 4           ; 0x02334455
+    // Result: { 0x1ABBCCDD, 0x5EEFF001, 0x02334455 }
+    const BitWord Mask = maskTrailingOnes<BitWord>(BitDistance);
+    const unsigned LSH = BITWORD_SIZE - BitDistance;
+
+    for (unsigned I = 0; I < NumWords - 1; ++I) {
+      Bits[I] >>= BitDistance;
+      Bits[I] |= (Bits[I + 1] & Mask) << LSH;
+    }
+
+    Bits[NumWords - 1] >>= BitDistance;
+
+    return *this;
+  }
+
+  BitVector &operator<<=(unsigned N) {
+    assert(N <= Size);
+    if (LLVM_UNLIKELY(empty() || N == 0))
+      return *this;
+
+    unsigned NumWords = NumBitWords(Size);
+    assert(NumWords >= 1);
+
+    wordShl(N / BITWORD_SIZE);
+
+    unsigned BitDistance = N % BITWORD_SIZE;
+    if (BitDistance == 0)
+      return *this;
+
+    // When the shift size is not a multiple of the word size, then we have
+    // a tricky situation where each word in succession needs to extract some
+    // of the bits from the previous word and or them into this word while
+    // shifting this word to make room for the new bits.  This has to be done
+    // for every word in the array.  This is similar to the algorithm outlined
+    // in operator>>=, but backwards.
+
+    // Since we're shifting each word left, some bits will fall off the end
+    // of each word to the left, and empty space will be created on the right.
+    // The first word in the array will lose bits permanently, so starting at
+    // the end, work backwards shifting each word to the left, and OR'ing
+    // in the bits from the end of the next word to the beginning of the
+    // current word.
+
+    // Example:
+    //   Starting with {0xAABBCCDD, 0xEEFF0011, 0x22334455} and shifting left
+    //   by 4 bits.
+    // Step 1: Word[2] <<= 4           ; 0x23344550
+    // Step 2: Word[2] |= 0x0000000E   ; 0x2334455E
+    // Step 3: Word[1] <<= 4           ; 0xEFF00110
+    // Step 4: Word[1] |= 0x0000000A   ; 0xEFF0011A
+    // Step 5: Word[0] <<= 4           ; 0xABBCCDD0
+    // Result: { 0xABBCCDD0, 0xEFF0011A, 0x2334455E }
+    const BitWord Mask = maskLeadingOnes<BitWord>(BitDistance);
+    const unsigned RSH = BITWORD_SIZE - BitDistance;
+
+    for (int I = NumWords - 1; I > 0; --I) {
+      Bits[I] <<= BitDistance;
+      Bits[I] |= (Bits[I - 1] & Mask) >> RSH;
+    }
+    Bits[0] <<= BitDistance;
+    clear_unused_bits();
+
+    return *this;
+  }
+
+  // Assignment operator.
+  const BitVector &operator=(const BitVector &RHS) {
+    if (this == &RHS) return *this;
+
+    Size = RHS.size();
+    unsigned RHSWords = NumBitWords(Size);
+    if (Size <= getBitCapacity()) {
+      if (Size)
+        std::memcpy(Bits.data(), RHS.Bits.data(), RHSWords * sizeof(BitWord));
+      clear_unused_bits();
+      return *this;
+    }
+
+    // Grow the bitvector to have enough elements.
+    unsigned NewCapacity = RHSWords;
+    assert(NewCapacity > 0 && "negative capacity?");
+    auto NewBits = allocate(NewCapacity);
+    std::memcpy(NewBits.data(), RHS.Bits.data(), NewCapacity * sizeof(BitWord));
+
+    // Destroy the old bits.
+    std::free(Bits.data());
+    Bits = NewBits;
+
+    return *this;
+  }
+
+  const BitVector &operator=(BitVector &&RHS) {
+    if (this == &RHS) return *this;
+
+    std::free(Bits.data());
+    Bits = RHS.Bits;
+    Size = RHS.Size;
+
+    RHS.Bits = MutableArrayRef<BitWord>();
+    RHS.Size = 0;
+
+    return *this;
+  }
+
+  void swap(BitVector &RHS) {
+    std::swap(Bits, RHS.Bits);
+    std::swap(Size, RHS.Size);
+  }
+
+  //===--------------------------------------------------------------------===//
+  // Portable bit mask operations.
+  //===--------------------------------------------------------------------===//
+  //
+  // These methods all operate on arrays of uint32_t, each holding 32 bits. The
+  // fixed word size makes it easier to work with literal bit vector constants
+  // in portable code.
+  //
+  // The LSB in each word is the lowest numbered bit.  The size of a portable
+  // bit mask is always a whole multiple of 32 bits.  If no bit mask size is
+  // given, the bit mask is assumed to cover the entire BitVector.
+
+  /// setBitsInMask - Add '1' bits from Mask to this vector. Don't resize.
+  /// This computes "*this |= Mask".
+  void setBitsInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
+    applyMask<true, false>(Mask, MaskWords);
+  }
+
+  /// clearBitsInMask - Clear any bits in this vector that are set in Mask.
+  /// Don't resize. This computes "*this &= ~Mask".
+  void clearBitsInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
+    applyMask<false, false>(Mask, MaskWords);
+  }
+
+  /// setBitsNotInMask - Add a bit to this vector for every '0' bit in Mask.
+  /// Don't resize.  This computes "*this |= ~Mask".
+  void setBitsNotInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
+    applyMask<true, true>(Mask, MaskWords);
+  }
+
+  /// clearBitsNotInMask - Clear a bit in this vector for every '0' bit in Mask.
+  /// Don't resize.  This computes "*this &= Mask".
+  void clearBitsNotInMask(const uint32_t *Mask, unsigned MaskWords = ~0u) {
+    applyMask<false, true>(Mask, MaskWords);
+  }
+
+private:
+  /// Perform a logical left shift of \p Count words by moving everything
+  /// \p Count words to the right in memory.
+  ///
+  /// While confusing, words are stored from least significant at Bits[0] to
+  /// most significant at Bits[NumWords-1].  A logical shift left, however,
+  /// moves the current least significant bit to a higher logical index, and
+  /// fills the previous least significant bits with 0.  Thus, we actually
+  /// need to move the bytes of the memory to the right, not to the left.
+  /// Example:
+  ///   Words = [0xBBBBAAAA, 0xDDDDFFFF, 0x00000000, 0xDDDD0000]
+  /// represents a BitVector where 0xBBBBAAAA contain the least significant
+  /// bits.  So if we want to shift the BitVector left by 2 words, we need to
+  /// turn this into 0x00000000 0x00000000 0xBBBBAAAA 0xDDDDFFFF by using a
+  /// memmove which moves right, not left.
+  void wordShl(uint32_t Count) {
+    if (Count == 0)
+      return;
+
+    uint32_t NumWords = NumBitWords(Size);
+
+    auto Src = Bits.take_front(NumWords).drop_back(Count);
+    auto Dest = Bits.take_front(NumWords).drop_front(Count);
+
+    // Since we always move Word-sized chunks of data with src and dest both
+    // aligned to a word-boundary, we don't need to worry about endianness
+    // here.
+    std::memmove(Dest.begin(), Src.begin(), Dest.size() * sizeof(BitWord));
+    std::memset(Bits.data(), 0, Count * sizeof(BitWord));
+    clear_unused_bits();
+  }
+
+  /// Perform a logical right shift of \p Count words by moving those
+  /// words to the left in memory.  See wordShl for more information.
+  ///
+  void wordShr(uint32_t Count) {
+    if (Count == 0)
+      return;
+
+    uint32_t NumWords = NumBitWords(Size);
+
+    auto Src = Bits.take_front(NumWords).drop_front(Count);
+    auto Dest = Bits.take_front(NumWords).drop_back(Count);
+    assert(Dest.size() == Src.size());
+
+    std::memmove(Dest.begin(), Src.begin(), Dest.size() * sizeof(BitWord));
+    std::memset(Dest.end(), 0, Count * sizeof(BitWord));
+  }
+
+  MutableArrayRef<BitWord> allocate(size_t NumWords) {
+    BitWord *RawBits = static_cast<BitWord *>(
+        safe_malloc(NumWords * sizeof(BitWord)));
+    return MutableArrayRef<BitWord>(RawBits, NumWords);
+  }
+
+  int next_unset_in_word(int WordIndex, BitWord Word) const {
+    unsigned Result = WordIndex * BITWORD_SIZE + countTrailingOnes(Word);
+    return Result < size() ? Result : -1;
+  }
+
+  unsigned NumBitWords(unsigned S) const {
+    return (S + BITWORD_SIZE-1) / BITWORD_SIZE;
+  }
+
+  // Set the unused bits in the high words.
+  void set_unused_bits(bool t = true) {
+    //  Set high words first.
+    unsigned UsedWords = NumBitWords(Size);
+    if (Bits.size() > UsedWords)
+      init_words(Bits.drop_front(UsedWords), t);
+
+    //  Then set any stray high bits of the last used word.
+    unsigned ExtraBits = Size % BITWORD_SIZE;
+    if (ExtraBits) {
+      BitWord ExtraBitMask = ~0UL << ExtraBits;
+      if (t)
+        Bits[UsedWords-1] |= ExtraBitMask;
+      else
+        Bits[UsedWords-1] &= ~ExtraBitMask;
+    }
+  }
+
+  // Clear the unused bits in the high words.
+  void clear_unused_bits() {
+    set_unused_bits(false);
+  }
+
+  void grow(unsigned NewSize) {
+    size_t NewCapacity = std::max<size_t>(NumBitWords(NewSize), Bits.size() * 2);
+    assert(NewCapacity > 0 && "realloc-ing zero space");
+    BitWord *NewBits = static_cast<BitWord *>(
+        safe_realloc(Bits.data(), NewCapacity * sizeof(BitWord)));
+    Bits = MutableArrayRef<BitWord>(NewBits, NewCapacity);
+    clear_unused_bits();
+  }
+
+  void init_words(MutableArrayRef<BitWord> B, bool t) {
+    if (B.size() > 0)
+      memset(B.data(), 0 - (int)t, B.size() * sizeof(BitWord));
+  }
+
+  template<bool AddBits, bool InvertMask>
+  void applyMask(const uint32_t *Mask, unsigned MaskWords) {
+    static_assert(BITWORD_SIZE % 32 == 0, "Unsupported BitWord size.");
+    MaskWords = std::min(MaskWords, (size() + 31) / 32);
+    const unsigned Scale = BITWORD_SIZE / 32;
+    unsigned i;
+    for (i = 0; MaskWords >= Scale; ++i, MaskWords -= Scale) {
+      BitWord BW = Bits[i];
+      // This inner loop should unroll completely when BITWORD_SIZE > 32.
+      for (unsigned b = 0; b != BITWORD_SIZE; b += 32) {
+        uint32_t M = *Mask++;
+        if (InvertMask) M = ~M;
+        if (AddBits) BW |=   BitWord(M) << b;
+        else         BW &= ~(BitWord(M) << b);
+      }
+      Bits[i] = BW;
+    }
+    for (unsigned b = 0; MaskWords; b += 32, --MaskWords) {
+      uint32_t M = *Mask++;
+      if (InvertMask) M = ~M;
+      if (AddBits) Bits[i] |=   BitWord(M) << b;
+      else         Bits[i] &= ~(BitWord(M) << b);
+    }
+    if (AddBits)
+      clear_unused_bits();
+  }
+
+public:
+  /// Return the size (in bytes) of the bit vector.
+  size_t getMemorySize() const { return Bits.size() * sizeof(BitWord); }
+  size_t getBitCapacity() const { return Bits.size() * BITWORD_SIZE; }
+};
+
+inline size_t capacity_in_bytes(const BitVector &X) {
+  return X.getMemorySize();
+}
+
+} // end namespace llvm
+
+namespace std {
+  /// Implement std::swap in terms of BitVector swap.
+  inline void
+  swap(llvm::BitVector &LHS, llvm::BitVector &RHS) {
+    LHS.swap(RHS);
+  }
+} // end namespace std
+
+#endif // LLVM_ADT_BITVECTOR_H