diff --git a/src/compiler/coalesced-live-ranges.h b/src/compiler/coalesced-live-ranges.h
new file mode 100644
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+++ b/src/compiler/coalesced-live-ranges.h
@@ -0,0 +1,158 @@
+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_COALESCED_LIVE_RANGES_H_
+#define V8_COALESCED_LIVE_RANGES_H_
+
+#include "src/compiler/register-allocator.h"
+#include "src/zone-containers.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+
+// Implementation detail for CoalescedLiveRanges.
+struct AllocatedInterval {
+  AllocatedInterval(LifetimePosition start, LifetimePosition end,
+                    LiveRange* range)
+      : start_(start), end_(end), range_(range) {}
+
+  LifetimePosition start_;
+  LifetimePosition end_;
+  LiveRange* range_;
+  bool operator<(const AllocatedInterval& other) const {
+    return start_ < other.start_;
+  }
+  bool operator>(const AllocatedInterval& other) const {
+    return start_ > other.start_;
+  }
+};
+typedef ZoneSet<AllocatedInterval> IntervalStore;
+
+
+// An iterator over conflicts of a live range, obtained from CoalescedLiveRanges
+// The design supports two main scenarios (see GreedyAllocator):
+// (1) observing each conflicting range, without mutating the allocations, and
+// (2) observing each conflicting range, and then moving to the next, after
+// removing the current conflict.
+class LiveRangeConflictIterator {
+ public:
+  // Current conflict. nullptr if no conflicts, or if we reached the end of
+  // conflicts.
+  LiveRange* Current() const;
+
+  // Get the next conflict. Caller should handle non-consecutive repetitions of
+  // the same range.
+  LiveRange* GetNext() { return InternalGetNext(false); }
+
+  // Get the next conflict, after evicting the current one. Caller may expect
+  // to never observe the same live range more than once.
+  LiveRange* RemoveCurrentAndGetNext() { return InternalGetNext(true); }
+
+ private:
+  friend class CoalescedLiveRanges;
+
+  typedef IntervalStore::const_iterator interval_iterator;
+  LiveRangeConflictIterator(const LiveRange* range, IntervalStore* store);
+
+  // Move the store iterator to  first interval intersecting query. Since the
+  // intervals are sorted, subsequent intervals intersecting query follow. May
+  // leave the store iterator at "end", meaning that the current query does not
+  // have an intersection.
+  void MovePosToFirstConflictForQuery();
+
+  // Move both query and store iterator to the first intersection, if any. If
+  // none, then it invalidates the iterator (IsFinished() == true)
+  void MovePosAndQueryToFirstConflict();
+
+  // Increment pos and skip over intervals belonging to the same range we
+  // started with (i.e. Current() before the call). It is possible that range
+  // will be seen again, but not consecutively.
+  void IncrementPosAndSkipOverRepetitions();
+
+  // Common implementation used by both GetNext as well as
+  // ClearCurrentAndGetNext.
+  LiveRange* InternalGetNext(bool clean_behind);
+
+  bool IsFinished() const { return query_ == nullptr; }
+
+  static AllocatedInterval AsAllocatedInterval(LifetimePosition pos) {
+    return AllocatedInterval(pos, LifetimePosition::Invalid(), nullptr);
+  }
+
+  // Intersection utilities.
+  static bool Intersects(LifetimePosition a_start, LifetimePosition a_end,
+                         LifetimePosition b_start, LifetimePosition b_end) {
+    return a_start < b_end && b_start < a_end;
+  }
+
+  bool QueryIntersectsAllocatedInterval() const {
+    DCHECK_NOT_NULL(query_);
+    return pos_ != intervals_->end() &&
+           Intersects(query_->start(), query_->end(), pos_->start_, pos_->end_);
+  }
+
+  void Invalidate() {
+    query_ = nullptr;
+    pos_ = intervals_->end();
+  }
+
+  const UseInterval* query_;
+  interval_iterator pos_;
+  IntervalStore* intervals_;
+};
+
+// Collection of live ranges allocated to the same register.
+// It supports efficiently finding all conflicts for a given, non-allocated
+// range. See AllocatedInterval.
+// Allocated live ranges do not intersect. At most, individual use intervals
+// touch. We store, for a live range, an AllocatedInterval corresponding to each
+// of that range's UseIntervals. We keep the list of AllocatedIntervals sorted
+// by starts. Then, given the non-intersecting property, we know that
+// consecutive AllocatedIntervals have the property that the "smaller"'s end is
+// less or equal to the "larger"'s start.
+// This allows for quick (logarithmic complexity) identification of the first
+// AllocatedInterval to conflict with a given LiveRange, and then for efficient
+// traversal of conflicts.
+class CoalescedLiveRanges : public ZoneObject {
+ public:
+  explicit CoalescedLiveRanges(Zone* zone) : intervals_(zone) {}
+  void clear() { intervals_.clear(); }
+
+  bool empty() const { return intervals_.empty(); }
+
+  // Iterate over each live range conflicting with the provided one.
+  // The same live range may be observed multiple, but non-consecutive times.
+  LiveRangeConflictIterator GetConflicts(const LiveRange* range);
+
+
+  // Allocates a range with a pre-calculated candidate weight.
+  void AllocateRange(LiveRange* range);
+
+  // Unit testing API, verifying that allocated intervals do not overlap.
+  bool VerifyAllocationsAreValidForTesting() const;
+
+ private:
+  static const float kAllocatedRangeMultiplier;
+
+  IntervalStore& intervals() { return intervals_; }
+  const IntervalStore& intervals() const { return intervals_; }
+
+  // Augment the weight of a range that is about to be allocated.
+  static void UpdateWeightAtAllocation(LiveRange* range);
+
+  // Reduce the weight of a range that has lost allocation.
+  static void UpdateWeightAtEviction(LiveRange* range);
+
+
+  IntervalStore intervals_;
+  DISALLOW_COPY_AND_ASSIGN(CoalescedLiveRanges);
+};
+
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8
+#endif  // V8_COALESCED_LIVE_RANGES_H_