Make common BitVector operations inline-able.

Change-Id: Ie25de4fae56c6712539f04172c42e3eff57df7ca

13 files changed, 350 insertions, 385 deletions

diff --git a/compiler/dex/mir_graph.cc b/compiler/dex/mir_graph.cc
index dee1361a50..16b529a5e6 100644
--- a/compiler/dex/mir_graph.cc
+++ b/compiler/dex/mir_graph.cc
@@ -19,6 +19,7 @@
 #include <inttypes.h>
 #include <queue>
 
+#include "base/bit_vector-inl.h"
 #include "base/stl_util.h"
 #include "compiler_internals.h"
 #include "dex_file-inl.h"
diff --git a/compiler/dex/mir_optimization.cc b/compiler/dex/mir_optimization.cc
index c7dd85c9c2..6658848570 100644
--- a/compiler/dex/mir_optimization.cc
+++ b/compiler/dex/mir_optimization.cc
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include "base/bit_vector-inl.h"
 #include "compiler_internals.h"
 #include "global_value_numbering.h"
 #include "local_value_numbering.h"
diff --git a/compiler/dex/ssa_transformation.cc b/compiler/dex/ssa_transformation.cc
index e26745ad5e..4a55de6891 100644
--- a/compiler/dex/ssa_transformation.cc
+++ b/compiler/dex/ssa_transformation.cc
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include "base/bit_vector-inl.h"
 #include "compiler_internals.h"
 #include "dataflow_iterator-inl.h"
 #include "utils/scoped_arena_containers.h"
diff --git a/compiler/oat_writer.cc b/compiler/oat_writer.cc
index 0fb1575475..41a91ed9d3 100644
--- a/compiler/oat_writer.cc
+++ b/compiler/oat_writer.cc
@@ -18,6 +18,7 @@
 
 #include <zlib.h>
 
+#include "base/allocator.h"
 #include "base/bit_vector.h"
 #include "base/stl_util.h"
 #include "base/unix_file/fd_file.h"
diff --git a/compiler/optimizing/register_allocator.cc b/compiler/optimizing/register_allocator.cc
index bd3a7d9767..da13b1ec55 100644
--- a/compiler/optimizing/register_allocator.cc
+++ b/compiler/optimizing/register_allocator.cc
@@ -16,6 +16,7 @@
 
 #include "register_allocator.h"
 
+#include "base/bit_vector-inl.h"
 #include "code_generator.h"
 #include "ssa_liveness_analysis.h"
 
diff --git a/compiler/optimizing/ssa_liveness_analysis.cc b/compiler/optimizing/ssa_liveness_analysis.cc
index fbdc0b9593..5de1ab9c31 100644
--- a/compiler/optimizing/ssa_liveness_analysis.cc
+++ b/compiler/optimizing/ssa_liveness_analysis.cc
@@ -16,6 +16,7 @@
 
 #include "ssa_liveness_analysis.h"
 
+#include "base/bit_vector-inl.h"
 #include "code_generator.h"
 #include "nodes.h"
 
diff --git a/compiler/utils/arena_bit_vector.cc b/compiler/utils/arena_bit_vector.cc
index 39f7d185a6..de35f3d197 100644
--- a/compiler/utils/arena_bit_vector.cc
+++ b/compiler/utils/arena_bit_vector.cc
@@ -16,11 +16,12 @@
 
 #include "arena_allocator.h"
 #include "arena_bit_vector.h"
+#include "base/allocator.h"
 
 namespace art {
 
 template <typename ArenaAlloc>
-class ArenaBitVectorAllocator : public Allocator {
+class ArenaBitVectorAllocator FINAL : public Allocator {
  public:
   explicit ArenaBitVectorAllocator(ArenaAlloc* arena) : arena_(arena) {}
   ~ArenaBitVectorAllocator() {}
@@ -37,7 +38,7 @@ class ArenaBitVectorAllocator : public Allocator {
   static void operator delete(void* p) {}  // Nop.
 
  private:
-  ArenaAlloc* arena_;
+  ArenaAlloc* const arena_;
   DISALLOW_COPY_AND_ASSIGN(ArenaBitVectorAllocator);
 };
 
diff --git a/compiler/utils/arena_bit_vector.h b/compiler/utils/arena_bit_vector.h
index 485ed76d12..c92658f7d6 100644
--- a/compiler/utils/arena_bit_vector.h
+++ b/compiler/utils/arena_bit_vector.h
@@ -51,23 +51,23 @@ std::ostream& operator<<(std::ostream& os, const OatBitMapKind& kind);
  * A BitVector implementation that uses Arena allocation.
  */
 class ArenaBitVector : public BitVector {
-  public:
-    ArenaBitVector(ArenaAllocator* arena, uint32_t start_bits, bool expandable,
-                   OatBitMapKind kind = kBitMapMisc);
-    ArenaBitVector(ScopedArenaAllocator* arena, uint32_t start_bits, bool expandable,
-                   OatBitMapKind kind = kBitMapMisc);
-    ~ArenaBitVector() {}
+ public:
+  ArenaBitVector(ArenaAllocator* arena, uint32_t start_bits, bool expandable,
+                 OatBitMapKind kind = kBitMapMisc);
+  ArenaBitVector(ScopedArenaAllocator* arena, uint32_t start_bits, bool expandable,
+                 OatBitMapKind kind = kBitMapMisc);
+  ~ArenaBitVector() {}
 
   static void* operator new(size_t size, ArenaAllocator* arena) {
-     return arena->Alloc(sizeof(ArenaBitVector), kArenaAllocGrowableBitMap);
+    return arena->Alloc(sizeof(ArenaBitVector), kArenaAllocGrowableBitMap);
   }
   static void* operator new(size_t size, ScopedArenaAllocator* arena) {
-     return arena->Alloc(sizeof(ArenaBitVector), kArenaAllocGrowableBitMap);
+    return arena->Alloc(sizeof(ArenaBitVector), kArenaAllocGrowableBitMap);
   }
   static void operator delete(void* p) {}  // Nop.
 
-  private:
-    const OatBitMapKind kind_;      // for memory use tuning. TODO: currently unused.
+ private:
+  const OatBitMapKind kind_;      // for memory use tuning. TODO: currently unused.
 };
 
 
diff --git a/runtime/base/allocator.cc b/runtime/base/allocator.cc
index 4f7753d476..3469eca8c3 100644
--- a/runtime/base/allocator.cc
+++ b/runtime/base/allocator.cc
@@ -23,7 +23,7 @@
 
 namespace art {
 
-class MallocAllocator : public Allocator {
+class MallocAllocator FINAL : public Allocator {
  public:
   explicit MallocAllocator() {}
   ~MallocAllocator() {}
@@ -42,7 +42,7 @@ class MallocAllocator : public Allocator {
 
 MallocAllocator g_malloc_allocator;
 
-class NoopAllocator : public Allocator {
+class NoopAllocator FINAL : public Allocator {
  public:
   explicit NoopAllocator() {}
   ~NoopAllocator() {}
diff --git a/runtime/base/bit_vector-inl.h b/runtime/base/bit_vector-inl.h
new file mode 100644
index 0000000000..dc13dd5b9f
--- /dev/null
+++ b/runtime/base/bit_vector-inl.h
@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_RUNTIME_BASE_BIT_VECTOR_INL_H_
+#define ART_RUNTIME_BASE_BIT_VECTOR_INL_H_
+
+#include "bit_vector.h"
+#include "logging.h"
+#include "utils.h"
+
+namespace art {
+
+inline bool BitVector::IndexIterator::operator==(const IndexIterator& other) const {
+  DCHECK(bit_storage_ == other.bit_storage_);
+  DCHECK_EQ(storage_size_, other.storage_size_);
+  return bit_index_ == other.bit_index_;
+}
+
+inline int BitVector::IndexIterator::operator*() const {
+  DCHECK_LT(bit_index_, BitSize());
+  return bit_index_;
+}
+
+inline BitVector::IndexIterator& BitVector::IndexIterator::operator++() {
+  DCHECK_LT(bit_index_, BitSize());
+  bit_index_ = FindIndex(bit_index_ + 1u);
+  return *this;
+}
+
+inline BitVector::IndexIterator BitVector::IndexIterator::operator++(int) {
+  IndexIterator result(*this);
+  ++*this;
+  return result;
+}
+
+inline uint32_t BitVector::IndexIterator::FindIndex(uint32_t start_index) const {
+  DCHECK_LE(start_index, BitSize());
+  uint32_t word_index = start_index / kWordBits;
+  if (UNLIKELY(word_index == storage_size_)) {
+    return start_index;
+  }
+  uint32_t word = bit_storage_[word_index];
+  // Mask out any bits in the first word we've already considered.
+  word &= static_cast<uint32_t>(-1) << (start_index & 0x1f);
+  while (word == 0u) {
+    ++word_index;
+    if (UNLIKELY(word_index == storage_size_)) {
+      return BitSize();
+    }
+    word = bit_storage_[word_index];
+  }
+  return word_index * 32u + CTZ(word);
+}
+
+inline void BitVector::ClearAllBits() {
+  memset(storage_, 0, storage_size_ * kWordBytes);
+}
+
+inline bool BitVector::Equal(const BitVector* src) const {
+  return (storage_size_ == src->GetStorageSize()) &&
+    (expandable_ == src->IsExpandable()) &&
+    (memcmp(storage_, src->GetRawStorage(), storage_size_ * sizeof(uint32_t)) == 0);
+}
+
+}  // namespace art
+
+#endif  // ART_RUNTIME_BASE_BIT_VECTOR_INL_H_
diff --git a/runtime/base/bit_vector.cc b/runtime/base/bit_vector.cc
index 1b9022e170..3d2f0deac5 100644
--- a/runtime/base/bit_vector.cc
+++ b/runtime/base/bit_vector.cc
@@ -16,20 +16,14 @@
 
 #include "bit_vector.h"
 
+#include "allocator.h"
+#include "bit_vector-inl.h"
+
 namespace art {
 
-// TODO: profile to make sure this is still a win relative to just using shifted masks.
-static uint32_t check_masks[32] = {
-  0x00000001, 0x00000002, 0x00000004, 0x00000008, 0x00000010,
-  0x00000020, 0x00000040, 0x00000080, 0x00000100, 0x00000200,
-  0x00000400, 0x00000800, 0x00001000, 0x00002000, 0x00004000,
-  0x00008000, 0x00010000, 0x00020000, 0x00040000, 0x00080000,
-  0x00100000, 0x00200000, 0x00400000, 0x00800000, 0x01000000,
-  0x02000000, 0x04000000, 0x08000000, 0x10000000, 0x20000000,
-  0x40000000, 0x80000000 };
-
-static inline uint32_t BitsToWords(uint32_t bits) {
-  return (bits + 31) >> 5;
+// The number of words necessary to encode bits.
+static constexpr uint32_t BitsToWords(uint32_t bits) {
+  return RoundUp(bits, 32) / 32;
 }
 
 // TODO: replace excessive argument defaulting when we are at gcc 4.7
@@ -40,10 +34,10 @@ BitVector::BitVector(uint32_t start_bits,
                      Allocator* allocator,
                      uint32_t storage_size,
                      uint32_t* storage)
-  : allocator_(allocator),
-    expandable_(expandable),
+  : storage_(storage),
     storage_size_(storage_size),
-    storage_(storage) {
+    allocator_(allocator),
+    expandable_(expandable) {
   COMPILE_ASSERT(sizeof(*storage_) == kWordBytes, check_word_bytes);
   COMPILE_ASSERT(sizeof(*storage_) * 8u == kWordBits, check_word_bits);
   if (storage_ == nullptr) {
@@ -56,59 +50,7 @@ BitVector::~BitVector() {
   allocator_->Free(storage_);
 }
 
-/*
- * Determine whether or not the specified bit is set.
- */
-bool BitVector::IsBitSet(uint32_t num) const {
-  // If the index is over the size:
-  if (num >= storage_size_ * kWordBits) {
-    // Whether it is expandable or not, this bit does not exist: thus it is not set.
-    return false;
-  }
-
-  return IsBitSet(storage_, num);
-}
-
-// Mark all bits bit as "clear".
-void BitVector::ClearAllBits() {
-  memset(storage_, 0, storage_size_ * kWordBytes);
-}
-
-// Mark the specified bit as "set".
-/*
- * TUNING: this could have pathologically bad growth/expand behavior.  Make sure we're
- * not using it badly or change resize mechanism.
- */
-void BitVector::SetBit(uint32_t num) {
-  if (num >= storage_size_ * kWordBits) {
-    DCHECK(expandable_) << "Attempted to expand a non-expandable bitmap to position " << num;
-
-    /* Round up to word boundaries for "num+1" bits */
-    uint32_t new_size = BitsToWords(num + 1);
-    DCHECK_GT(new_size, storage_size_);
-    uint32_t *new_storage =
-        static_cast<uint32_t*>(allocator_->Alloc(new_size * kWordBytes));
-    memcpy(new_storage, storage_, storage_size_ * kWordBytes);
-    // Zero out the new storage words.
-    memset(&new_storage[storage_size_], 0, (new_size - storage_size_) * kWordBytes);
-    // TOTO: collect stats on space wasted because of resize.
-    storage_ = new_storage;
-    storage_size_ = new_size;
-  }
-
-  storage_[num >> 5] |= check_masks[num & 0x1f];
-}
-
-// Mark the specified bit as "unset".
-void BitVector::ClearBit(uint32_t num) {
-  // If the index is over the size, we don't have to do anything, it is cleared.
-  if (num < storage_size_ * kWordBits) {
-    // Otherwise, go ahead and clear it.
-    storage_[num >> 5] &= ~check_masks[num & 0x1f];
-  }
-}
-
-bool BitVector::SameBitsSet(const BitVector *src) {
+bool BitVector::SameBitsSet(const BitVector *src) const {
   int our_highest = GetHighestBitSet();
   int src_highest = src->GetHighestBitSet();
 
@@ -134,7 +76,6 @@ bool BitVector::SameBitsSet(const BitVector *src) {
   return (memcmp(storage_, src->GetRawStorage(), our_highest_index * kWordBytes) == 0);
 }
 
-// Intersect with another bit vector.
 void BitVector::Intersect(const BitVector* src) {
   uint32_t src_storage_size = src->storage_size_;
 
@@ -155,9 +96,6 @@ void BitVector::Intersect(const BitVector* src) {
   }
 }
 
-/*
- * Union with another bit vector.
- */
 bool BitVector::Union(const BitVector* src) {
   // Get the highest bit to determine how much we need to expand.
   int highest_bit = src->GetHighestBitSet();
@@ -175,8 +113,7 @@ bool BitVector::Union(const BitVector* src) {
   if (storage_size_ < src_size) {
     changed = true;
 
-    // Set it to reallocate.
-    SetBit(highest_bit);
+    EnsureSize(highest_bit);
 
     // Paranoid: storage size should be big enough to hold this bit now.
     DCHECK_LT(static_cast<uint32_t> (highest_bit), storage_size_ * kWordBits);
@@ -242,21 +179,20 @@ bool BitVector::UnionIfNotIn(const BitVector* union_with, const BitVector* not_i
 }
 
 void BitVector::Subtract(const BitVector *src) {
-    uint32_t src_size = src->storage_size_;
+  uint32_t src_size = src->storage_size_;
 
-    // We only need to operate on bytes up to the smaller of the sizes of the two operands.
-    unsigned int min_size = (storage_size_ > src_size) ? src_size : storage_size_;
+  // We only need to operate on bytes up to the smaller of the sizes of the two operands.
+  unsigned int min_size = (storage_size_ > src_size) ? src_size : storage_size_;
 
-    // Difference until max, we know both accept it:
-    //   There is no need to do more:
-    //     If we are bigger than src, the upper bits are unchanged.
-    //     If we are smaller than src, the non-existant upper bits are 0 and thus can't get subtracted.
-    for (uint32_t idx = 0; idx < min_size; idx++) {
-        storage_[idx] &= (~(src->GetRawStorageWord(idx)));
-    }
+  // Difference until max, we know both accept it:
+  //   There is no need to do more:
+  //     If we are bigger than src, the upper bits are unchanged.
+  //     If we are smaller than src, the non-existant upper bits are 0 and thus can't get subtracted.
+  for (uint32_t idx = 0; idx < min_size; idx++) {
+    storage_[idx] &= (~(src->GetRawStorageWord(idx)));
+  }
 }
 
-// Count the number of bits that are set.
 uint32_t BitVector::NumSetBits() const {
   uint32_t count = 0;
   for (uint32_t word = 0; word < storage_size_; word++) {
@@ -265,17 +201,11 @@ uint32_t BitVector::NumSetBits() const {
   return count;
 }
 
-// Count the number of bits that are set in range [0, end).
 uint32_t BitVector::NumSetBits(uint32_t end) const {
   DCHECK_LE(end, storage_size_ * kWordBits);
   return NumSetBits(storage_, end);
 }
 
-/*
- * Mark specified number of bits as "set". Cannot set all bits like ClearAll
- * since there might be unused bits - setting those to one will confuse the
- * iterator.
- */
 void BitVector::SetInitialBits(uint32_t num_bits) {
   // If num_bits is 0, clear everything.
   if (num_bits == 0) {
@@ -288,7 +218,7 @@ void BitVector::SetInitialBits(uint32_t num_bits) {
 
   uint32_t idx;
   // We can set every storage element with -1.
-  for (idx = 0; idx < (num_bits >> 5); idx++) {
+  for (idx = 0; idx < WordIndex(num_bits); idx++) {
     storage_[idx] = -1;
   }
 
@@ -312,20 +242,8 @@ int BitVector::GetHighestBitSet() const {
     uint32_t value = storage_[idx];
 
     if (value != 0) {
-      // Shift right for the counting.
-      value /= 2;
-
-      int cnt = 0;
-
-      // Count the bits.
-      while (value > 0) {
-        value /= 2;
-        cnt++;
-      }
-
-      // Return cnt + how many storage units still remain * the number of bits per unit.
-      int res = cnt + (idx * kWordBits);
-      return res;
+      // Return highest bit set in value plus bits from previous storage indexes.
+      return 31 - CLZ(value) + (idx * kWordBits);
     }
   }
 
@@ -333,23 +251,6 @@ int BitVector::GetHighestBitSet() const {
   return -1;
 }
 
-bool BitVector::EnsureSizeAndClear(unsigned int num) {
-  // Check if the bitvector is expandable.
-  if (IsExpandable() == false) {
-    return false;
-  }
-
-  if (num > 0) {
-    // Now try to expand by setting the last bit.
-    SetBit(num - 1);
-  }
-
-  // We must clear all bits as per our specification.
-  ClearAllBits();
-
-  return true;
-}
-
 void BitVector::Copy(const BitVector *src) {
   // Get highest bit set, we only need to copy till then.
   int highest_bit = src->GetHighestBitSet();
@@ -375,13 +276,8 @@ void BitVector::Copy(const BitVector *src) {
   }
 }
 
-bool BitVector::IsBitSet(const uint32_t* storage, uint32_t num) {
-  uint32_t val = storage[num >> 5] & check_masks[num & 0x1f];
-  return (val != 0);
-}
-
 uint32_t BitVector::NumSetBits(const uint32_t* storage, uint32_t end) {
-  uint32_t word_end = end >> 5;
+  uint32_t word_end = WordIndex(end);
   uint32_t partial_word_bits = end & 0x1f;
 
   uint32_t count = 0u;
@@ -400,45 +296,6 @@ void BitVector::Dump(std::ostream& os, const char *prefix) const {
   os << buffer.str() << std::endl;
 }
 
-
-void BitVector::DumpDotHelper(bool last_entry, FILE* file, std::ostringstream& buffer) const {
-  // Now print it to the file.
-  fprintf(file, "    {%s}", buffer.str().c_str());
-
-  // If it isn't the last entry, add a |.
-  if (last_entry == false) {
-    fprintf(file, "|");
-  }
-
-  // Add the \n.
-  fprintf(file, "\\\n");
-}
-
-void BitVector::DumpDot(FILE* file, const char* prefix, bool last_entry) const {
-  std::ostringstream buffer;
-  DumpHelper(prefix, buffer);
-  DumpDotHelper(last_entry, file, buffer);
-}
-
-void BitVector::DumpIndicesDot(FILE* file, const char* prefix, bool last_entry) const {
-  std::ostringstream buffer;
-  DumpIndicesHelper(prefix, buffer);
-  DumpDotHelper(last_entry, file, buffer);
-}
-
-void BitVector::DumpIndicesHelper(const char* prefix, std::ostringstream& buffer) const {
-  // Initialize it.
-  if (prefix != nullptr) {
-    buffer << prefix;
-  }
-
-  for (size_t i = 0; i < storage_size_ * kWordBits; i++) {
-    if (IsBitSet(i)) {
-      buffer << i << " ";
-    }
-  }
-}
-
 void BitVector::DumpHelper(const char* prefix, std::ostringstream& buffer) const {
   // Initialize it.
   if (prefix != nullptr) {
@@ -452,4 +309,22 @@ void BitVector::DumpHelper(const char* prefix, std::ostringstream& buffer) const
   buffer << ')';
 }
 
+void BitVector::EnsureSize(uint32_t idx) {
+  if (idx >= storage_size_ * kWordBits) {
+    DCHECK(expandable_) << "Attempted to expand a non-expandable bitmap to position " << idx;
+
+    /* Round up to word boundaries for "idx+1" bits */
+    uint32_t new_size = BitsToWords(idx + 1);
+    DCHECK_GT(new_size, storage_size_);
+    uint32_t *new_storage =
+        static_cast<uint32_t*>(allocator_->Alloc(new_size * kWordBytes));
+    memcpy(new_storage, storage_, storage_size_ * kWordBytes);
+    // Zero out the new storage words.
+    memset(&new_storage[storage_size_], 0, (new_size - storage_size_) * kWordBytes);
+    // TOTO: collect stats on space wasted because of resize.
+    storage_ = new_storage;
+    storage_size_ = new_size;
+  }
+}
+
 }  // namespace art
diff --git a/runtime/base/bit_vector.h b/runtime/base/bit_vector.h
index fb1646f7fc..1e28a27e94 100644
--- a/runtime/base/bit_vector.h
+++ b/runtime/base/bit_vector.h
@@ -18,235 +18,237 @@
 #define ART_RUNTIME_BASE_BIT_VECTOR_H_
 
 #include <stdint.h>
-#include <stddef.h>
-
-#include "allocator.h"
-#include "base/logging.h"
-#include "utils.h"
+#include <iterator>
 
 namespace art {
 
+class Allocator;
+
 /*
  * Expanding bitmap, used for tracking resources.  Bits are numbered starting
  * from zero.  All operations on a BitVector are unsynchronized.
  */
 class BitVector {
-  public:
-    class IndexContainer;
-
-    /**
-     * @brief Convenient iterator across the indexes of the BitVector's set bits.
-     *
-     * @details IndexIterator is a Forward iterator (C++11: 24.2.5) from the lowest
-     * to the highest index of the BitVector's set bits. Instances can be retrieved
-     * only through BitVector::Indexes() which returns an IndexContainer wrapper
-     * object with begin() and end() suitable for range-based loops:
-     *   for (uint32_t idx : bit_vector.Indexes()) {
-     *     // Use idx.
-     *   }
-     */
-    class IndexIterator
-        : std::iterator<std::forward_iterator_tag, uint32_t, ptrdiff_t, void, uint32_t> {
-      public:
-        bool operator==(const IndexIterator& other) const {
-          DCHECK(bit_storage_ == other.bit_storage_);
-          DCHECK_EQ(storage_size_, other.storage_size_);
-          return bit_index_ == other.bit_index_;
-        }
-
-        bool operator!=(const IndexIterator& other) const {
-          return !(*this == other);
-        }
-
-        int operator*() const {
-          DCHECK_LT(bit_index_, BitSize());
-          return bit_index_;
-        }
-
-        IndexIterator& operator++() {
-          DCHECK_LT(bit_index_, BitSize());
-          bit_index_ = FindIndex(bit_index_ + 1u);
-          return *this;
-        }
-
-        IndexIterator operator++(int) {
-          IndexIterator result(*this);
-          ++*this;
-          return result;
-        }
-
-        // Helper function to check for end without comparing with bit_vector.Indexes().end().
-        bool Done() const {
-          return bit_index_ == BitSize();
-        }
-
-      private:
-        struct begin_tag { };
-        struct end_tag { };
-
-        IndexIterator(const BitVector* bit_vector, begin_tag)
-          : bit_storage_(bit_vector->GetRawStorage()),
-            storage_size_(bit_vector->storage_size_),
-            bit_index_(FindIndex(0u)) { }
-
-        IndexIterator(const BitVector* bit_vector, end_tag)
-          : bit_storage_(bit_vector->GetRawStorage()),
-            storage_size_(bit_vector->storage_size_),
-            bit_index_(BitSize()) { }
-
-        uint32_t BitSize() const {
-          return storage_size_ * kWordBits;
-        }
-
-        uint32_t FindIndex(uint32_t start_index) const {
-          DCHECK_LE(start_index, BitSize());
-          uint32_t word_index = start_index / kWordBits;
-          if (UNLIKELY(word_index == storage_size_)) {
-            return start_index;
-          }
-          uint32_t word = bit_storage_[word_index];
-          // Mask out any bits in the first word we've already considered.
-          word &= static_cast<uint32_t>(-1) << (start_index & 0x1f);
-          while (word == 0u) {
-            ++word_index;
-            if (UNLIKELY(word_index == storage_size_)) {
-              return BitSize();
-            }
-            word = bit_storage_[word_index];
-          }
-          return word_index * 32u + CTZ(word);
-        }
-
-        const uint32_t* const bit_storage_;
-        const uint32_t storage_size_;  // Size of vector in words.
-        uint32_t bit_index_;           // Current index (size in bits).
-
-        friend class BitVector::IndexContainer;
-    };
-
-    /**
-     * @brief BitVector wrapper class for iteration across indexes of set bits.
-     */
-    class IndexContainer {
-     public:
-      explicit IndexContainer(const BitVector* bit_vector) : bit_vector_(bit_vector) { }
-
-      IndexIterator begin() const {
-        return IndexIterator(bit_vector_, IndexIterator::begin_tag());
-      }
-
-      IndexIterator end() const {
-        return IndexIterator(bit_vector_, IndexIterator::end_tag());
-      }
-
-     private:
-      const BitVector* const bit_vector_;
-    };
-
-    BitVector(uint32_t start_bits,
-              bool expandable,
-              Allocator* allocator,
-              uint32_t storage_size = 0,
-              uint32_t* storage = nullptr);
-
-    virtual ~BitVector();
-
-    void SetBit(uint32_t num);
-    void ClearBit(uint32_t num);
-    bool IsBitSet(uint32_t num) const;
-    void ClearAllBits();
-    void SetInitialBits(uint32_t num_bits);
-
-    void Copy(const BitVector* src);
-    void Intersect(const BitVector* src2);
-    bool Union(const BitVector* src);
-
-    // Set bits of union_with that are not in not_in.
-    bool UnionIfNotIn(const BitVector* union_with, const BitVector* not_in);
-
-    void Subtract(const BitVector* src);
-    // Are we equal to another bit vector?  Note: expandability attributes must also match.
-    bool Equal(const BitVector* src) {
-      return (storage_size_ == src->GetStorageSize()) &&
-        (expandable_ == src->IsExpandable()) &&
-        (memcmp(storage_, src->GetRawStorage(), storage_size_ * sizeof(uint32_t)) == 0);
+ public:
+  class IndexContainer;
+
+  /**
+   * @brief Convenient iterator across the indexes of the BitVector's set bits.
+   *
+   * @details IndexIterator is a Forward iterator (C++11: 24.2.5) from the lowest
+   * to the highest index of the BitVector's set bits. Instances can be retrieved
+   * only through BitVector::Indexes() which returns an IndexContainer wrapper
+   * object with begin() and end() suitable for range-based loops:
+   *   for (uint32_t idx : bit_vector.Indexes()) {
+   *     // Use idx.
+   *   }
+   */
+  class IndexIterator :
+      std::iterator<std::forward_iterator_tag, uint32_t, ptrdiff_t, void, uint32_t> {
+   public:
+    bool operator==(const IndexIterator& other) const;
+
+    bool operator!=(const IndexIterator& other) const {
+      return !(*this == other);
     }
 
-    /**
-     * @brief Are all the bits set the same?
-     * @details expandability and size can differ as long as the same bits are set.
-     */
-    bool SameBitsSet(const BitVector *src);
+    int operator*() const;
 
-    uint32_t NumSetBits() const;
+    IndexIterator& operator++();
 
-    // Number of bits set in range [0, end).
-    uint32_t NumSetBits(uint32_t end) const;
+    IndexIterator operator++(int);
 
-    IndexContainer Indexes() const {
-      return IndexContainer(this);
+    // Helper function to check for end without comparing with bit_vector.Indexes().end().
+    bool Done() const {
+      return bit_index_ == BitSize();
     }
 
-    uint32_t GetStorageSize() const { return storage_size_; }
-    bool IsExpandable() const { return expandable_; }
-    uint32_t GetRawStorageWord(size_t idx) const { return storage_[idx]; }
-    uint32_t* GetRawStorage() { return storage_; }
-    const uint32_t* GetRawStorage() const { return storage_; }
-    size_t GetSizeOf() const { return storage_size_ * kWordBytes; }
+   private:
+    struct begin_tag { };
+    struct end_tag { };
 
-    /**
-     * @return the highest bit set, -1 if none are set
-     */
-    int GetHighestBitSet() const;
+    IndexIterator(const BitVector* bit_vector, begin_tag)
+      : bit_storage_(bit_vector->GetRawStorage()),
+        storage_size_(bit_vector->storage_size_),
+        bit_index_(FindIndex(0u)) { }
 
-    // Is bit set in storage. (No range check.)
-    static bool IsBitSet(const uint32_t* storage, uint32_t num);
-    // Number of bits set in range [0, end) in storage. (No range check.)
-    static uint32_t NumSetBits(const uint32_t* storage, uint32_t end);
+    IndexIterator(const BitVector* bit_vector, end_tag)
+      : bit_storage_(bit_vector->GetRawStorage()),
+        storage_size_(bit_vector->storage_size_),
+        bit_index_(BitSize()) { }
 
-    bool EnsureSizeAndClear(unsigned int num);
+    uint32_t BitSize() const {
+      return storage_size_ * kWordBits;
+    }
 
-    void Dump(std::ostream& os, const char* prefix) const;
+    uint32_t FindIndex(uint32_t start_index) const;
+    const uint32_t* const bit_storage_;
+    const uint32_t storage_size_;  // Size of vector in words.
+    uint32_t bit_index_;           // Current index (size in bits).
 
-    /**
-     * @brief last_entry is this the last entry for the dot dumping
-     * @details if not, a "|" is appended to the dump.
-     */
-    void DumpDot(FILE* file, const char* prefix, bool last_entry = false) const;
+    friend class BitVector::IndexContainer;
+  };
 
-    /**
-     * @brief last_entry is this the last entry for the dot dumping
-     * @details if not, a "|" is appended to the dump.
-     */
-    void DumpIndicesDot(FILE* file, const char* prefix, bool last_entry = false) const;
+  /**
+   * @brief BitVector wrapper class for iteration across indexes of set bits.
+   */
+  class IndexContainer {
+   public:
+    explicit IndexContainer(const BitVector* bit_vector) : bit_vector_(bit_vector) { }
 
-  protected:
-    /**
-     * @brief Dump the bitvector into buffer in a 00101..01 format.
-     * @param buffer the ostringstream used to dump the bitvector into.
-     */
-    void DumpHelper(const char* prefix, std::ostringstream& buffer) const;
+    IndexIterator begin() const {
+      return IndexIterator(bit_vector_, IndexIterator::begin_tag());
+    }
 
-    /**
-     * @brief Dump the bitvector in a 1 2 5 8 format, where the numbers are the bit set.
-     * @param buffer the ostringstream used to dump the bitvector into.
-     */
-    void DumpIndicesHelper(const char* prefix, std::ostringstream& buffer) const;
+    IndexIterator end() const {
+      return IndexIterator(bit_vector_, IndexIterator::end_tag());
+    }
+
+   private:
+    const BitVector* const bit_vector_;
+  };
+
+  BitVector(uint32_t start_bits,
+            bool expandable,
+            Allocator* allocator,
+            uint32_t storage_size = 0,
+            uint32_t* storage = nullptr);
 
-    /**
-     * @brief Wrapper to perform the bitvector dumping with the .dot format.
-     * @param buffer the ostringstream used to dump the bitvector into.
+  virtual ~BitVector();
+
+  // Mark the specified bit as "set".
+  void SetBit(uint32_t idx) {
+    /*
+     * TUNING: this could have pathologically bad growth/expand behavior.  Make sure we're
+     * not using it badly or change resize mechanism.
      */
-    void DumpDotHelper(bool last_entry, FILE* file, std::ostringstream& buffer) const;
+    if (idx >= storage_size_ * kWordBits) {
+      EnsureSize(idx);
+    }
+    storage_[WordIndex(idx)] |= BitMask(idx);
+  }
+
+  // Mark the specified bit as "unset".
+  void ClearBit(uint32_t idx) {
+    // If the index is over the size, we don't have to do anything, it is cleared.
+    if (idx < storage_size_ * kWordBits) {
+      // Otherwise, go ahead and clear it.
+      storage_[WordIndex(idx)] &= ~BitMask(idx);
+    }
+  }
+
+  // Determine whether or not the specified bit is set.
+  bool IsBitSet(uint32_t idx) const {
+    // If the index is over the size, whether it is expandable or not, this bit does not exist:
+    // thus it is not set.
+    return (idx < (storage_size_ * kWordBits)) && IsBitSet(storage_, idx);
+  }
+
+  // Mark all bits bit as "clear".
+  void ClearAllBits();
+
+  // Mark specified number of bits as "set". Cannot set all bits like ClearAll since there might
+  // be unused bits - setting those to one will confuse the iterator.
+  void SetInitialBits(uint32_t num_bits);
+
+  void Copy(const BitVector* src);
+
+  // Intersect with another bit vector.
+  void Intersect(const BitVector* src2);
+
+  // Union with another bit vector.
+  bool Union(const BitVector* src);
+
+  // Set bits of union_with that are not in not_in.
+  bool UnionIfNotIn(const BitVector* union_with, const BitVector* not_in);
+
+  void Subtract(const BitVector* src);
+
+  // Are we equal to another bit vector?  Note: expandability attributes must also match.
+  bool Equal(const BitVector* src) const;
+
+  /**
+   * @brief Are all the bits set the same?
+   * @details expandability and size can differ as long as the same bits are set.
+   */
+  bool SameBitsSet(const BitVector *src) const;
+
+  // Count the number of bits that are set.
+  uint32_t NumSetBits() const;
+
+  // Count the number of bits that are set in range [0, end).
+  uint32_t NumSetBits(uint32_t end) const;
+
+  IndexContainer Indexes() const {
+    return IndexContainer(this);
+  }
+
+  uint32_t GetStorageSize() const {
+    return storage_size_;
+  }
+
+  bool IsExpandable() const {
+    return expandable_;
+  }
+
+  uint32_t GetRawStorageWord(size_t idx) const {
+    return storage_[idx];
+  }
+
+  uint32_t* GetRawStorage() {
+    return storage_;
+  }
+
+  const uint32_t* GetRawStorage() const {
+    return storage_;
+  }
+
+  size_t GetSizeOf() const {
+    return storage_size_ * kWordBytes;
+  }
+
+  /**
+   * @return the highest bit set, -1 if none are set
+   */
+  int GetHighestBitSet() const;
+
+  // Is bit set in storage. (No range check.)
+  static bool IsBitSet(const uint32_t* storage, uint32_t idx) {
+    return (storage[WordIndex(idx)] & BitMask(idx)) != 0;
+  }
+
+  // Number of bits set in range [0, end) in storage. (No range check.)
+  static uint32_t NumSetBits(const uint32_t* storage, uint32_t end);
+
+  void Dump(std::ostream& os, const char* prefix) const;
+
+ private:
+  /**
+   * @brief Dump the bitvector into buffer in a 00101..01 format.
+   * @param buffer the ostringstream used to dump the bitvector into.
+   */
+  void DumpHelper(const char* prefix, std::ostringstream& buffer) const;
+
+  // Ensure there is space for a bit at idx.
+  void EnsureSize(uint32_t idx);
+
+  // The index of the word within storage.
+  static constexpr uint32_t WordIndex(uint32_t idx) {
+    return idx >> 5;
+  }
+
+  // A bit mask to extract the bit for the given index.
+  static constexpr uint32_t BitMask(uint32_t idx) {
+    return 1 << (idx & 0x1f);
+  }
 
-  private:
-    static constexpr uint32_t kWordBytes = sizeof(uint32_t);
-    static constexpr uint32_t kWordBits = kWordBytes * 8;
+  static constexpr uint32_t kWordBytes = sizeof(uint32_t);
+  static constexpr uint32_t kWordBits = kWordBytes * 8;
 
-    Allocator* const allocator_;
-    const bool expandable_;         // expand bitmap if we run out?
-    uint32_t   storage_size_;       // current size, in 32-bit words.
-    uint32_t*  storage_;
+  uint32_t*  storage_;            // The storage for the bit vector.
+  uint32_t   storage_size_;       // Current size, in 32-bit words.
+  Allocator* const allocator_;    // Allocator if expandable.
+  const bool expandable_;         // Should the bitmap expand if too small?
 };
 
 
diff --git a/runtime/base/bit_vector_test.cc b/runtime/base/bit_vector_test.cc
index 1403f50c04..df5d79d893 100644
--- a/runtime/base/bit_vector_test.cc
+++ b/runtime/base/bit_vector_test.cc
@@ -16,7 +16,8 @@
 
 #include <memory>
 
-#include "bit_vector.h"
+#include "allocator.h"
+#include "bit_vector-inl.h"
 #include "gtest/gtest.h"
 
 namespace art {