[Isolates] Merge crankshaft (r5922 from bleeding_edge).

src/lithium-allocator.cc

+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "lithium-allocator.h"
+
+#include "data-flow.h"
+#include "hydrogen.h"
+#include "string-stream.h"
+
+#if V8_TARGET_ARCH_IA32
+#include "ia32/lithium-ia32.h"
+#elif V8_TARGET_ARCH_X64
+#include "x64/lithium-x64.h"
+#elif V8_TARGET_ARCH_ARM
+#include "arm/lithium-arm.h"
+#else
+#error "Unknown architecture."
+#endif
+
+namespace v8 {
+namespace internal {
+
+
+#define DEFINE_OPERAND_CACHE(name, type)            \
+  name name::cache[name::kNumCachedOperands];       \
+  void name::SetupCache() {                         \
+    for (int i = 0; i < kNumCachedOperands; i++) {  \
+      cache[i].ConvertTo(type, i);                  \
+    }                                               \
+  }
+
+DEFINE_OPERAND_CACHE(LConstantOperand, CONSTANT_OPERAND)
+DEFINE_OPERAND_CACHE(LStackSlot,       STACK_SLOT)
+DEFINE_OPERAND_CACHE(LDoubleStackSlot, DOUBLE_STACK_SLOT)
+DEFINE_OPERAND_CACHE(LRegister,        REGISTER)
+DEFINE_OPERAND_CACHE(LDoubleRegister,  DOUBLE_REGISTER)
+
+#undef DEFINE_OPERAND_CACHE
+
+
+static inline LifetimePosition Min(LifetimePosition a, LifetimePosition b) {
+  return a.Value() < b.Value() ? a : b;
+}
+
+
+static inline LifetimePosition Max(LifetimePosition a, LifetimePosition b) {
+  return a.Value() > b.Value() ? a : b;
+}
+
+
+void LOperand::PrintTo(StringStream* stream) {
+  LUnallocated* unalloc = NULL;
+  switch (kind()) {
+    case INVALID:
+      break;
+    case UNALLOCATED:
+      unalloc = LUnallocated::cast(this);
+      stream->Add("v%d", unalloc->virtual_register());
+      switch (unalloc->policy()) {
+        case LUnallocated::NONE:
+          break;
+        case LUnallocated::FIXED_REGISTER: {
+          const char* register_name =
+              Register::AllocationIndexToString(unalloc->fixed_index());
+          stream->Add("(=%s)", register_name);
+          break;
+        }
+        case LUnallocated::FIXED_DOUBLE_REGISTER: {
+          const char* double_register_name =
+              DoubleRegister::AllocationIndexToString(unalloc->fixed_index());
+          stream->Add("(=%s)", double_register_name);
+          break;
+        }
+        case LUnallocated::FIXED_SLOT:
+          stream->Add("(=%dS)", unalloc->fixed_index());
+          break;
+        case LUnallocated::MUST_HAVE_REGISTER:
+          stream->Add("(R)");
+          break;
+        case LUnallocated::WRITABLE_REGISTER:
+          stream->Add("(WR)");
+          break;
+        case LUnallocated::SAME_AS_FIRST_INPUT:
+          stream->Add("(1)");
+          break;
+        case LUnallocated::SAME_AS_ANY_INPUT:
+          stream->Add("(A)");
+          break;
+        case LUnallocated::ANY:
+          stream->Add("(-)");
+          break;
+        case LUnallocated::IGNORE:
+          stream->Add("(0)");
+          break;
+      }
+      break;
+    case CONSTANT_OPERAND:
+      stream->Add("[constant:%d]", index());
+      break;
+    case STACK_SLOT:
+      stream->Add("[stack:%d]", index());
+      break;
+    case DOUBLE_STACK_SLOT:
+      stream->Add("[double_stack:%d]", index());
+      break;
+    case REGISTER:
+      stream->Add("[%s|R]", Register::AllocationIndexToString(index()));
+      break;
+    case DOUBLE_REGISTER:
+      stream->Add("[%s|R]", DoubleRegister::AllocationIndexToString(index()));
+      break;
+    case ARGUMENT:
+      stream->Add("[arg:%d]", index());
+      break;
+  }
+}
+
+int LOperand::VirtualRegister() {
+  LUnallocated* unalloc = LUnallocated::cast(this);
+  return unalloc->virtual_register();
+}
+
+
+bool UsePosition::RequiresRegister() const {
+  return requires_reg_;
+}
+
+
+bool UsePosition::RegisterIsBeneficial() const {
+  return register_beneficial_;
+}
+
+
+void UseInterval::SplitAt(LifetimePosition pos) {
+  ASSERT(Contains(pos) && pos.Value() != start().Value());
+  UseInterval* after = new UseInterval(pos, end_);
+  after->next_ = next_;
+  next_ = after;
+  end_ = pos;
+}
+
+
+#ifdef DEBUG
+
+
+void LiveRange::Verify() const {
+  UsePosition* cur = first_pos_;
+  while (cur != NULL) {
+    ASSERT(Start().Value() <= cur->pos().Value() &&
+           cur->pos().Value() <= End().Value());
+    cur = cur->next();
+  }
+}
+
+
+bool LiveRange::HasOverlap(UseInterval* target) const {
+  UseInterval* current_interval = first_interval_;
+  while (current_interval != NULL) {
+    // Intervals overlap if the start of one is contained in the other.
+    if (current_interval->Contains(target->start()) ||
+        target->Contains(current_interval->start())) {
+      return true;
+    }
+    current_interval = current_interval->next();
+  }
+  return false;
+}
+
+
+#endif
+
+
+UsePosition* LiveRange::NextUsePosition(LifetimePosition start) {
+  UsePosition* use_pos = last_processed_use_;
+  if (use_pos == NULL) use_pos = first_pos();
+  while (use_pos != NULL && use_pos->pos().Value() < start.Value()) {
+    use_pos = use_pos->next();
+  }
+  last_processed_use_ = use_pos;
+  return use_pos;
+}
+
+
+UsePosition* LiveRange::NextUsePositionRegisterIsBeneficial(
+    LifetimePosition start) {
+  UsePosition* pos = NextUsePosition(start);
+  while (pos != NULL && !pos->RegisterIsBeneficial()) {
+    pos = pos->next();
+  }
+  return pos;
+}
+
+
+UsePosition* LiveRange::NextRegisterPosition(LifetimePosition start) {
+  UsePosition* pos = NextUsePosition(start);
+  while (pos != NULL && !pos->RequiresRegister()) {
+    pos = pos->next();
+  }
+  return pos;
+}
+
+
+bool LiveRange::CanBeSpilled(LifetimePosition pos) {
+  // TODO(kmillikin): Comment. Now.
+  if (pos.Value() <= Start().Value() && HasRegisterAssigned()) return false;
+
+  // We cannot spill a live range that has a use requiring a register
+  // at the current or the immediate next position.
+  UsePosition* use_pos = NextRegisterPosition(pos);
+  if (use_pos == NULL) return true;
+  return use_pos->pos().Value() > pos.NextInstruction().Value();
+}
+
+
+UsePosition* LiveRange::FirstPosWithHint() const {
+  UsePosition* pos = first_pos_;
+  while (pos != NULL && !pos->HasHint()) pos = pos->next();
+  return pos;
+}
+
+
+LOperand* LiveRange::CreateAssignedOperand() {
+  LOperand* op = NULL;
+  if (HasRegisterAssigned()) {
+    ASSERT(!IsSpilled());
+    if (assigned_double_) {
+      op = LDoubleRegister::Create(assigned_register());
+    } else {
+      op = LRegister::Create(assigned_register());
+    }
+  } else if (IsSpilled()) {
+    ASSERT(!HasRegisterAssigned());
+    op = TopLevel()->GetSpillOperand();
+    ASSERT(!op->IsUnallocated());
+  } else {
+    LUnallocated* unalloc = new LUnallocated(LUnallocated::NONE);
+    unalloc->set_virtual_register(id_);
+    op = unalloc;
+  }
+  return op;
+}
+
+
+UseInterval* LiveRange::FirstSearchIntervalForPosition(
+    LifetimePosition position) const {
+  if (current_interval_ == NULL) return first_interval_;
+  if (current_interval_->start().Value() > position.Value()) {
+    current_interval_ = NULL;
+    return first_interval_;
+  }
+  return current_interval_;
+}
+
+
+void LiveRange::AdvanceLastProcessedMarker(
+    UseInterval* to_start_of, LifetimePosition but_not_past) const {
+  if (to_start_of == NULL) return;
+  if (to_start_of->start().Value() > but_not_past.Value()) return;
+  LifetimePosition start =
+      current_interval_ == NULL ? LifetimePosition::Invalid()
+                                : current_interval_->start();
+  if (to_start_of->start().Value() > start.Value()) {
+    current_interval_ = to_start_of;
+  }
+}
+
+
+void LiveRange::SplitAt(LifetimePosition position, LiveRange* result) {
+  ASSERT(Start().Value() <= position.Value());
+  ASSERT(result->IsEmpty());
+  // Find the last interval that ends before the position. If the
+  // position is contained in one of the intervals in the chain, we
+  // split that interval and use the first part.
+  UseInterval* current = FirstSearchIntervalForPosition(position);
+  while (current != NULL) {
+    if (current->Contains(position)) {
+      current->SplitAt(position);
+      break;
+    }
+    UseInterval* next = current->next();
+    if (next->start().Value() >= position.Value()) break;
+    current = next;
+  }
+
+  // Partition original use intervals to the two live ranges.
+  UseInterval* before = current;
+  UseInterval* after = before->next();
+  result->last_interval_ = (last_interval_ == before)
+      ? after            // Only interval in the range after split.
+      : last_interval_;  // Last interval of the original range.
+  result->first_interval_ = after;
+  last_interval_ = before;
+
+  // Find the last use position before the split and the first use
+  // position after it.
+  UsePosition* use_after = first_pos_;
+  UsePosition* use_before = NULL;
+  while (use_after != NULL && use_after->pos().Value() <= position.Value()) {
+    use_before = use_after;
+    use_after = use_after->next();
+  }
+
+  // Partition original use positions to the two live ranges.
+  if (use_before != NULL) {
+    use_before->next_ = NULL;
+  } else {
+    first_pos_ = NULL;
+  }
+  result->first_pos_ = use_after;
+
+  // Link the new live range in the chain before any of the other
+  // ranges linked from the range before the split.
+  result->parent_ = (parent_ == NULL) ? this : parent_;
+  result->next_ = next_;
+  next_ = result;
+
+#ifdef DEBUG
+  Verify();
+  result->Verify();
+#endif
+}
+
+
+// This implements an ordering on live ranges so that they are ordered by their
+// start positions.  This is needed for the correctness of the register
+// allocation algorithm.  If two live ranges start at the same offset then there
+// is a tie breaker based on where the value is first used.  This part of the
+// ordering is merely a heuristic.
+bool LiveRange::ShouldBeAllocatedBefore(const LiveRange* other) const {
+  LifetimePosition start = Start();
+  LifetimePosition other_start = other->Start();
+  if (start.Value() == other_start.Value()) {
+    UsePosition* pos = FirstPosWithHint();
+    if (pos == NULL) return false;
+    UsePosition* other_pos = other->first_pos();
+    if (other_pos == NULL) return true;
+    return pos->pos().Value() < other_pos->pos().Value();
+  }
+  return start.Value() < other_start.Value();
+}
+
+
+void LiveRange::ShortenTo(LifetimePosition start) {
+  LAllocator::TraceAlloc("Shorten live range %d to [%d\n", id_, start.Value());
+  ASSERT(first_interval_ != NULL);
+  ASSERT(first_interval_->start().Value() <= start.Value());
+  ASSERT(start.Value() < first_interval_->end().Value());
+  first_interval_->set_start(start);
+}
+
+
+void LiveRange::EnsureInterval(LifetimePosition start, LifetimePosition end) {
+  LAllocator::TraceAlloc("Ensure live range %d in interval [%d %d[\n",
+                         id_,
+                         start.Value(),
+                         end.Value());
+  LifetimePosition new_end = end;
+  while (first_interval_ != NULL &&
+         first_interval_->start().Value() <= end.Value()) {
+    if (first_interval_->end().Value() > end.Value()) {
+      new_end = first_interval_->end();
+    }
+    first_interval_ = first_interval_->next();
+  }
+
+  UseInterval* new_interval = new UseInterval(start, new_end);
+  new_interval->next_ = first_interval_;
+  first_interval_ = new_interval;
+  if (new_interval->next() == NULL) {
+    last_interval_ = new_interval;
+  }
+}
+
+
+void LiveRange::AddUseInterval(LifetimePosition start, LifetimePosition end) {
+  LAllocator::TraceAlloc("Add to live range %d interval [%d %d[\n",
+                         id_,
+                         start.Value(),
+                         end.Value());
+  if (first_interval_ == NULL) {
+    UseInterval* interval = new UseInterval(start, end);
+    first_interval_ = interval;
+    last_interval_ = interval;
+  } else {
+    if (end.Value() == first_interval_->start().Value()) {
+      first_interval_->set_start(start);
+    } else if (end.Value() < first_interval_->start().Value()) {
+      UseInterval* interval = new UseInterval(start, end);
+      interval->set_next(first_interval_);
+      first_interval_ = interval;
+    } else {
+      // Order of instruction's processing (see ProcessInstructions) guarantees
+      // that each new use interval either precedes or intersects with
+      // last added interval.
+      ASSERT(start.Value() < first_interval_->end().Value());
+      first_interval_->start_ = Min(start, first_interval_->start_);
+      first_interval_->end_ = Max(end, first_interval_->end_);
+    }
+  }
+}
+
+
+UsePosition* LiveRange::AddUsePosition(LifetimePosition pos,
+                                       LOperand* operand) {
+  LAllocator::TraceAlloc("Add to live range %d use position %d\n",
+                         id_,
+                         pos.Value());
+  UsePosition* use_pos = new UsePosition(pos, operand);
+  UsePosition* prev = NULL;
+  UsePosition* current = first_pos_;
+  while (current != NULL && current->pos().Value() < pos.Value()) {
+    prev = current;
+    current = current->next();
+  }
+
+  if (prev == NULL) {
+    use_pos->set_next(first_pos_);
+    first_pos_ = use_pos;
+  } else {
+    use_pos->next_ = prev->next_;
+    prev->next_ = use_pos;
+  }
+
+  return use_pos;
+}
+
+
+void LiveRange::ConvertOperands() {
+  LOperand* op = CreateAssignedOperand();
+  UsePosition* use_pos = first_pos();
+  while (use_pos != NULL) {
+    ASSERT(Start().Value() <= use_pos->pos().Value() &&
+           use_pos->pos().Value() <= End().Value());
+
+    if (use_pos->HasOperand()) {
+      ASSERT(op->IsRegister() || op->IsDoubleRegister() ||
+             !use_pos->RequiresRegister());
+      use_pos->operand()->ConvertTo(op->kind(), op->index());
+    }
+    use_pos = use_pos->next();
+  }
+}
+
+
+UsePosition* LiveRange::AddUsePosition(LifetimePosition pos) {
+  return AddUsePosition(pos, CreateAssignedOperand());
+}
+
+
+bool LiveRange::CanCover(LifetimePosition position) const {
+  if (IsEmpty()) return false;
+  return Start().Value() <= position.Value() &&
+         position.Value() < End().Value();
+}
+
+
+bool LiveRange::Covers(LifetimePosition position) {
+  if (!CanCover(position)) return false;
+  UseInterval* start_search = FirstSearchIntervalForPosition(position);
+  for (UseInterval* interval = start_search;
+       interval != NULL;
+       interval = interval->next()) {
+    ASSERT(interval->next() == NULL ||
+           interval->next()->start().Value() >= interval->start().Value());
+    AdvanceLastProcessedMarker(interval, position);
+    if (interval->Contains(position)) return true;
+    if (interval->start().Value() > position.Value()) return false;
+  }
+  return false;
+}
+
+
+LifetimePosition LiveRange::FirstIntersection(LiveRange* other) {
+  UseInterval* b = other->first_interval();
+  if (b == NULL) return LifetimePosition::Invalid();
+  LifetimePosition advance_last_processed_up_to = b->start();
+  UseInterval* a = FirstSearchIntervalForPosition(b->start());
+  while (a != NULL && b != NULL) {
+    if (a->start().Value() > other->End().Value()) break;
+    if (b->start().Value() > End().Value()) break;
+    LifetimePosition cur_intersection = a->Intersect(b);
+    if (cur_intersection.IsValid()) {
+      return cur_intersection;
+    }
+    if (a->start().Value() < b->start().Value()) {
+      a = a->next();
+      if (a == NULL && a->start().Value() > other->End().Value()) break;
+      AdvanceLastProcessedMarker(a, advance_last_processed_up_to);
+    } else {
+      b = b->next();
+    }
+  }
+  return LifetimePosition::Invalid();
+}
+
+
+void LAllocator::InitializeLivenessAnalysis() {
+  // Initialize the live_in sets for each block to NULL.
+  int block_count = graph()->blocks()->length();
+  live_in_sets_.Initialize(block_count);
+  live_in_sets_.AddBlock(NULL, block_count);
+}
+
+
+BitVector* LAllocator::ComputeLiveOut(HBasicBlock* block) {
+  // Compute live out for the given block, except not including backward
+  // successor edges.
+  BitVector* live_out = new BitVector(next_virtual_register_);
+
+  // Process all successor blocks.
+  HBasicBlock* successor = block->end()->FirstSuccessor();
+  while (successor != NULL) {
+    // Add values live on entry to the successor. Note the successor's
+    // live_in will not be computed yet for backwards edges.
+    BitVector* live_in = live_in_sets_[successor->block_id()];
+    if (live_in != NULL) live_out->Union(*live_in);
+
+    // All phi input operands corresponding to this successor edge are live
+    // out from this block.
+    int index = successor->PredecessorIndexOf(block);
+    const ZoneList<HPhi*>* phis = successor->phis();
+    for (int i = 0; i < phis->length(); ++i) {
+      HPhi* phi = phis->at(i);
+      if (!phi->OperandAt(index)->IsConstant()) {
+        live_out->Add(phi->OperandAt(index)->id());
+      }
+    }
+
+    // Check if we are done with second successor.
+    if (successor == block->end()->SecondSuccessor()) break;
+
+    successor = block->end()->SecondSuccessor();
+  }
+
+  return live_out;
+}
+
+
+void LAllocator::AddInitialIntervals(HBasicBlock* block,
+                                     BitVector* live_out) {
+  // Add an interval that includes the entire block to the live range for
+  // each live_out value.
+  LifetimePosition start = LifetimePosition::FromInstructionIndex(
+      block->first_instruction_index());
+  LifetimePosition end = LifetimePosition::FromInstructionIndex(
+      block->last_instruction_index());
+  BitVector::Iterator iterator(live_out);
+  while (!iterator.Done()) {
+    int operand_index = iterator.Current();
+    LiveRange* range = LiveRangeFor(operand_index);
+    if (!range->IsEmpty() &&
+        range->Start().Value() == end.NextInstruction().Value()) {
+      range->AddUseInterval(start, end.NextInstruction());
+    } else {
+      range->AddUseInterval(start, end);
+    }
+    iterator.Advance();
+  }
+}
+
+
+int LAllocator::FixedDoubleLiveRangeID(int index) {
+  return -index - 1 - Register::kNumAllocatableRegisters;
+}
+
+
+LOperand* LAllocator::AllocateFixed(LUnallocated* operand,
+                                    int pos,
+                                    bool is_tagged) {
+  TraceAlloc("Allocating fixed reg for op %d\n", operand->virtual_register());
+  ASSERT(operand->HasFixedPolicy());
+  if (operand->policy() == LUnallocated::FIXED_SLOT) {
+    operand->ConvertTo(LOperand::STACK_SLOT, operand->fixed_index());
+  } else if (operand->policy() == LUnallocated::FIXED_REGISTER) {
+    int reg_index = operand->fixed_index();
+    operand->ConvertTo(LOperand::REGISTER, reg_index);
+  } else if (operand->policy() == LUnallocated::FIXED_DOUBLE_REGISTER) {
+    int reg_index = operand->fixed_index();
+    operand->ConvertTo(LOperand::DOUBLE_REGISTER, reg_index);
+  } else {
+    UNREACHABLE();
+  }
+  if (is_tagged) {
+    TraceAlloc("Fixed reg is tagged at %d\n", pos);
+    LInstruction* instr = chunk_->instructions()->at(pos);
+    if (instr->HasPointerMap()) {
+      instr->pointer_map()->RecordPointer(operand);
+    }
+  }
+  return operand;
+}
+
+
+LiveRange* LAllocator::FixedLiveRangeFor(int index) {
+  if (index >= fixed_live_ranges_.length()) {
+    fixed_live_ranges_.AddBlock(NULL,
+                                index - fixed_live_ranges_.length() + 1);
+  }
+
+  LiveRange* result = fixed_live_ranges_[index];
+  if (result == NULL) {
+    result = new LiveRange(FixedLiveRangeID(index));
+    ASSERT(result->IsFixed());
+    result->set_assigned_register(index, false);
+    fixed_live_ranges_[index] = result;
+  }
+  return result;
+}
+
+
+LiveRange* LAllocator::FixedDoubleLiveRangeFor(int index) {
+  if (index >= fixed_double_live_ranges_.length()) {
+    fixed_double_live_ranges_.AddBlock(NULL,
+                                index - fixed_double_live_ranges_.length() + 1);
+  }
+
+  LiveRange* result = fixed_double_live_ranges_[index];
+  if (result == NULL) {
+    result = new LiveRange(FixedDoubleLiveRangeID(index));
+    ASSERT(result->IsFixed());
+    result->set_assigned_register(index, true);
+    fixed_double_live_ranges_[index] = result;
+  }
+  return result;
+}
+
+LiveRange* LAllocator::LiveRangeFor(int index) {
+  if (index >= live_ranges_.length()) {
+    live_ranges_.AddBlock(NULL, index - live_ranges_.length() + 1);
+  }
+  LiveRange* result = live_ranges_[index];
+  if (result == NULL) {
+    result = new LiveRange(index);
+    live_ranges_[index] = result;
+  }
+  return result;
+}
+
+
+LGap* LAllocator::GetLastGap(HBasicBlock* block) const {
+  int last_instruction = block->last_instruction_index();
+  int index = chunk_->NearestGapPos(last_instruction);
+  return chunk_->GetGapAt(index);
+}
+
+
+HPhi* LAllocator::LookupPhi(LOperand* operand) const {
+  if (!operand->IsUnallocated()) return NULL;
+  int index = operand->VirtualRegister();
+  HValue* instr = graph()->LookupValue(index);
+  if (instr != NULL && instr->IsPhi()) {
+    return HPhi::cast(instr);
+  }
+  return NULL;
+}
+
+
+LiveRange* LAllocator::LiveRangeFor(LOperand* operand) {
+  if (operand->IsUnallocated()) {
+    return LiveRangeFor(LUnallocated::cast(operand)->virtual_register());
+  } else if (operand->IsRegister()) {
+    return FixedLiveRangeFor(operand->index());
+  } else if (operand->IsDoubleRegister()) {
+    return FixedDoubleLiveRangeFor(operand->index());
+  } else {
+    return NULL;
+  }
+}
+
+
+void LAllocator::Define(LifetimePosition position,
+                        LOperand* operand,
+                        LOperand* hint) {
+  LiveRange* range = LiveRangeFor(operand);
+  if (range == NULL) return;
+
+  if (range->IsEmpty() || range->Start().Value() > position.Value()) {
+    // Can happen if there is a definition without use.
+    range->AddUseInterval(position, position.NextInstruction());
+    range->AddUsePosition(position.NextInstruction(), NULL);
+  } else {
+    range->ShortenTo(position);
+  }
+
+  if (operand->IsUnallocated()) {
+    LUnallocated* unalloc_operand = LUnallocated::cast(operand);
+    range->AddUsePosition(position, unalloc_operand)->set_hint(hint);
+  }
+}
+
+
+void LAllocator::Use(LifetimePosition block_start,
+                     LifetimePosition position,
+                     LOperand* operand,
+                     LOperand* hint) {
+  LiveRange* range = LiveRangeFor(operand);
+  if (range == NULL) return;
+  if (operand->IsUnallocated()) {
+    LUnallocated* unalloc_operand = LUnallocated::cast(operand);
+    range->AddUsePosition(position, unalloc_operand)->set_hint(hint);
+  }
+  range->AddUseInterval(block_start, position);
+}
+
+
+void LAllocator::AddConstraintsGapMove(int index,
+                                       LOperand* from,
+                                       LOperand* to) {
+  LGap* gap = chunk_->GetGapAt(index);
+  LParallelMove* move = gap->GetOrCreateParallelMove(LGap::START);
+  if (from->IsUnallocated()) {
+    const ZoneList<LMoveOperands>* move_operands = move->move_operands();
+    for (int i = 0; i < move_operands->length(); ++i) {
+      LMoveOperands cur = move_operands->at(i);
+      LOperand* cur_to = cur.to();
+      if (cur_to->IsUnallocated()) {
+        if (cur_to->VirtualRegister() == from->VirtualRegister()) {
+          move->AddMove(cur.from(), to);
+          return;
+        }
+      }
+    }
+  }
+  move->AddMove(from, to);
+}
+
+
+void LAllocator::MeetRegisterConstraints(HBasicBlock* block) {
+  int start = block->first_instruction_index();
+  int end = block->last_instruction_index();
+  for (int i = start; i <= end; ++i) {
+    if (chunk_->IsGapAt(i)) {
+      InstructionSummary* summary = NULL;
+      InstructionSummary* prev_summary = NULL;
+      if (i < end) summary = GetSummary(i + 1);
+      if (i > start) prev_summary = GetSummary(i - 1);
+      MeetConstraintsBetween(prev_summary, summary, i);
+    }
+  }
+}
+
+
+void LAllocator::MeetConstraintsBetween(InstructionSummary* first,
+                                        InstructionSummary* second,
+                                        int gap_index) {
+  // Handle fixed temporaries.
+  if (first != NULL) {
+    for (int i = 0; i < first->TempCount(); ++i) {
+      LUnallocated* temp = LUnallocated::cast(first->TempAt(i));
+      if (temp->HasFixedPolicy()) {
+        AllocateFixed(temp, gap_index - 1, false);
+      }
+    }
+  }
+
+  // Handle fixed output operand.
+  if (first != NULL && first->Output() != NULL) {
+    LUnallocated* first_output = LUnallocated::cast(first->Output());
+    LiveRange* range = LiveRangeFor(first_output->VirtualRegister());
+    bool assigned = false;
+    if (first_output->HasFixedPolicy()) {
+      LUnallocated* output_copy = first_output->CopyUnconstrained();
+      bool is_tagged = HasTaggedValue(first_output->VirtualRegister());
+      AllocateFixed(first_output, gap_index, is_tagged);
+
+      // This value is produced on the stack, we never need to spill it.
+      if (first_output->IsStackSlot()) {
+        range->SetSpillOperand(first_output);
+        range->SetSpillStartIndex(gap_index - 1);
+        assigned = true;
+      }
+      chunk_->AddGapMove(gap_index, first_output, output_copy);
+    }
+
+    if (!assigned) {
+      range->SetSpillStartIndex(gap_index);
+
+      // This move to spill operand is not a real use. Liveness analysis
+      // and splitting of live ranges do not account for it.
+      // Thus it should be inserted to a lifetime position corresponding to
+      // the instruction end.
+      LGap* gap = chunk_->GetGapAt(gap_index);
+      LParallelMove* move = gap->GetOrCreateParallelMove(LGap::BEFORE);
+      move->AddMove(first_output, range->GetSpillOperand());
+    }
+  }
+
+  // Handle fixed input operands of second instruction.
+  if (second != NULL) {
+    for (int i = 0; i < second->InputCount(); ++i) {
+      LUnallocated* cur_input = LUnallocated::cast(second->InputAt(i));
+      if (cur_input->HasFixedPolicy()) {
+        LUnallocated* input_copy = cur_input->CopyUnconstrained();
+        bool is_tagged = HasTaggedValue(cur_input->VirtualRegister());
+        AllocateFixed(cur_input, gap_index + 1, is_tagged);
+        AddConstraintsGapMove(gap_index, input_copy, cur_input);
+      } else if (cur_input->policy() == LUnallocated::WRITABLE_REGISTER) {
+        LUnallocated* input_copy = cur_input->CopyUnconstrained();
+        cur_input->set_virtual_register(next_virtual_register_++);
+        second->AddTemp(cur_input);
+        AddConstraintsGapMove(gap_index, input_copy, cur_input);
+      }
+    }
+  }
+
+  // Handle "output same as input" for second instruction.
+  if (second != NULL && second->Output() != NULL) {
+    LUnallocated* second_output = LUnallocated::cast(second->Output());
+    if (second_output->HasSameAsInputPolicy()) {
+      LUnallocated* cur_input = LUnallocated::cast(second->InputAt(0));
+      int output_vreg = second_output->VirtualRegister();
+      int input_vreg = cur_input->VirtualRegister();
+
+      LUnallocated* input_copy = cur_input->CopyUnconstrained();
+      cur_input->set_virtual_register(second_output->virtual_register());
+      AddConstraintsGapMove(gap_index, input_copy, cur_input);
+
+      if (HasTaggedValue(input_vreg) && !HasTaggedValue(output_vreg)) {
+        int index = gap_index + 1;
+        LInstruction* instr = chunk_->instructions()->at(index);
+        if (instr->HasPointerMap()) {
+          instr->pointer_map()->RecordPointer(input_copy);
+        }
+      } else if (!HasTaggedValue(input_vreg) && HasTaggedValue(output_vreg)) {
+        // The input is assumed to immediately have a tagged representation,
+        // before the pointer map can be used. I.e. the pointer map at the
+        // instruction will include the output operand (whose value at the
+        // beginning of the instruction is equal to the input operand). If
+        // this is not desired, then the pointer map at this instruction needs
+        // to be adjusted manually.
+      }
+    }
+  }
+}
+
+
+void LAllocator::ProcessInstructions(HBasicBlock* block, BitVector* live) {
+  int block_start = block->first_instruction_index();
+  int index = block->last_instruction_index();
+
+  LifetimePosition block_start_position =
+      LifetimePosition::FromInstructionIndex(block_start);
+
+  while (index >= block_start) {
+    LifetimePosition curr_position =
+        LifetimePosition::FromInstructionIndex(index);
+
+    if (chunk_->IsGapAt(index)) {
+      // We have a gap at this position.
+      LGap* gap = chunk_->GetGapAt(index);
+      LParallelMove* move = gap->GetOrCreateParallelMove(LGap::START);
+      const ZoneList<LMoveOperands>* move_operands = move->move_operands();
+      for (int i = 0; i < move_operands->length(); ++i) {
+        LMoveOperands* cur = &move_operands->at(i);
+        if (cur->IsIgnored()) continue;
+        LOperand* from = cur->from();
+        LOperand* to = cur->to();
+        HPhi* phi = LookupPhi(to);
+        LOperand* hint = to;
+        if (phi != NULL) {
+          // This is a phi resolving move.
+          if (!phi->block()->IsLoopHeader()) {
+            hint = LiveRangeFor(phi->id())->FirstHint();
+          }
+        } else {
+          if (to->IsUnallocated()) {
+            if (live->Contains(to->VirtualRegister())) {
+              Define(curr_position, to, from);
+              live->Remove(to->VirtualRegister());
+            } else {
+              cur->Eliminate();
+              continue;
+            }
+          } else {
+            Define(curr_position, to, from);
+          }
+        }
+        Use(block_start_position, curr_position, from, hint);
+        if (from->IsUnallocated()) {
+          live->Add(from->VirtualRegister());
+        }
+      }
+    } else {
+      ASSERT(!chunk_->IsGapAt(index));
+      InstructionSummary* summary = GetSummary(index);
+
+      if (summary != NULL) {
+        LOperand* output = summary->Output();
+        if (output != NULL) {
+          if (output->IsUnallocated()) live->Remove(output->VirtualRegister());
+          Define(curr_position, output, NULL);
+        }
+
+        if (summary->IsCall()) {
+          for (int i = 0; i < Register::kNumAllocatableRegisters; ++i) {
+            if (output == NULL || !output->IsRegister() ||
+                output->index() != i) {
+              LiveRange* range = FixedLiveRangeFor(i);
+              range->AddUseInterval(curr_position,
+                                    curr_position.InstructionEnd());
+            }
+          }
+          for (int i = 0; i < DoubleRegister::kNumAllocatableRegisters; ++i) {
+            if (output == NULL || !output->IsDoubleRegister() ||
+                output->index() != i) {
+              LiveRange* range = FixedDoubleLiveRangeFor(i);
+              range->AddUseInterval(curr_position,
+                                    curr_position.InstructionEnd());
+            }
+          }
+        }
+
+        for (int i = 0; i < summary->InputCount(); ++i) {
+          LOperand* input = summary->InputAt(i);
+
+          LifetimePosition use_pos;
+          if (input->IsUnallocated() &&
+              LUnallocated::cast(input)->IsUsedAtStart()) {
+            use_pos = curr_position;
+          } else {
+            use_pos = curr_position.InstructionEnd();
+          }
+
+          Use(block_start_position, use_pos, input, NULL);
+          if (input->IsUnallocated()) live->Add(input->VirtualRegister());
+        }
+
+        for (int i = 0; i < summary->TempCount(); ++i) {
+          LOperand* temp = summary->TempAt(i);
+          if (summary->IsCall()) {
+            if (temp->IsRegister()) continue;
+            if (temp->IsUnallocated()) {
+              LUnallocated* temp_unalloc = LUnallocated::cast(temp);
+              if (temp_unalloc->HasFixedPolicy()) {
+                continue;
+              }
+            }
+          }
+          Use(block_start_position, curr_position, temp, NULL);
+          Define(curr_position.PrevInstruction(), temp, NULL);
+        }
+      }
+    }
+
+    index = index - 1;
+  }
+}
+
+
+void LAllocator::ResolvePhis(HBasicBlock* block) {
+  const ZoneList<HPhi*>* phis = block->phis();
+  for (int i = 0; i < phis->length(); ++i) {
+    HPhi* phi = phis->at(i);
+    LUnallocated* phi_operand = new LUnallocated(LUnallocated::NONE);
+    phi_operand->set_virtual_register(phi->id());
+    for (int j = 0; j < phi->OperandCount(); ++j) {
+      HValue* op = phi->OperandAt(j);
+      LOperand* operand = NULL;
+      if (op->IsConstant() && op->EmitAtUses()) {
+        HConstant* constant = HConstant::cast(op);
+        operand = chunk_->DefineConstantOperand(constant);
+      } else {
+        ASSERT(!op->EmitAtUses());
+        LUnallocated* unalloc = new LUnallocated(LUnallocated::NONE);
+        unalloc->set_virtual_register(op->id());
+        operand = unalloc;
+      }
+      HBasicBlock* cur_block = block->predecessors()->at(j);
+      // The gap move must be added without any special processing as in
+      // the AddConstraintsGapMove.
+      chunk_->AddGapMove(cur_block->last_instruction_index() - 1,
+                         operand,
+                         phi_operand);
+    }
+
+    LiveRange* live_range = LiveRangeFor(phi->id());
+    LLabel* label = chunk_->GetLabel(phi->block()->block_id());
+    label->GetOrCreateParallelMove(LGap::START)->
+        AddMove(phi_operand, live_range->GetSpillOperand());
+    live_range->SetSpillStartIndex(phi->block()->first_instruction_index());
+  }
+}
+
+
+void LAllocator::Allocate(LChunk* chunk) {
+  ASSERT(chunk_ == NULL);
+  chunk_ = chunk;
+  MeetRegisterConstraints();
+  ResolvePhis();
+  BuildLiveRanges();
+  AllocateGeneralRegisters();
+  AllocateDoubleRegisters();
+  PopulatePointerMaps();
+  if (has_osr_entry_) ProcessOsrEntry();
+  ConnectRanges();
+  ResolveControlFlow();
+}
+
+
+void LAllocator::MeetRegisterConstraints() {
+  HPhase phase("Register constraints", chunk());
+  const ZoneList<HBasicBlock*>* blocks = graph()->blocks();
+  for (int i = 0; i < blocks->length(); ++i) {
+    HBasicBlock* block = blocks->at(i);
+    MeetRegisterConstraints(block);
+  }
+}
+
+
+void LAllocator::ResolvePhis() {
+  HPhase phase("Resolve phis", chunk());
+
+  // Process the blocks in reverse order.
+  const ZoneList<HBasicBlock*>* blocks = graph()->blocks();
+  for (int block_id = blocks->length() - 1; block_id >= 0; --block_id) {
+    HBasicBlock* block = blocks->at(block_id);
+    ResolvePhis(block);
+  }
+}
+
+
+void LAllocator::ResolveControlFlow(LiveRange* range,
+                                    HBasicBlock* block,
+                                    HBasicBlock* pred) {
+  LifetimePosition pred_end =
+      LifetimePosition::FromInstructionIndex(pred->last_instruction_index()).
+      PrevInstruction();
+
+  LifetimePosition cur_start =
+      LifetimePosition::FromInstructionIndex(block->first_instruction_index());
+  LiveRange* pred_cover = NULL;
+  LiveRange* cur_cover = NULL;
+  LiveRange* cur_range = range;
+  while (cur_range != NULL && (cur_cover == NULL || pred_cover == NULL)) {
+    if (cur_range->CanCover(cur_start)) {
+      ASSERT(cur_cover == NULL);
+      cur_cover = cur_range;
+    }
+    if (cur_range->CanCover(pred_end)) {
+      ASSERT(pred_cover == NULL);
+      pred_cover = cur_range;
+    }
+    cur_range = cur_range->next();
+  }
+
+  if (cur_cover->IsSpilled()) return;
+  ASSERT(pred_cover != NULL && cur_cover != NULL);
+  if (pred_cover != cur_cover) {
+    LOperand* pred_op = pred_cover->CreateAssignedOperand();
+    LOperand* cur_op = cur_cover->CreateAssignedOperand();
+    if (!pred_op->Equals(cur_op)) {
+      LGap* gap = NULL;
+      if (block->predecessors()->length() == 1) {
+        gap = chunk_->GetGapAt(block->first_instruction_index());
+      } else {
+        ASSERT(pred->end()->SecondSuccessor() == NULL);
+        gap = GetLastGap(pred);
+      }
+      gap->GetOrCreateParallelMove(LGap::START)->AddMove(pred_op, cur_op);
+    }
+  }
+}
+
+
+LParallelMove* LAllocator::GetConnectingParallelMove(LifetimePosition pos) {
+  int index = pos.InstructionIndex();
+  if (chunk_->IsGapAt(index)) {
+    LGap* gap = chunk_->GetGapAt(index);
+    return gap->GetOrCreateParallelMove(
+        pos.IsInstructionStart() ? LGap::START : LGap::END);
+  }
+  int gap_pos = pos.IsInstructionStart() ? (index - 1) : (index + 1);
+  return chunk_->GetGapAt(gap_pos)->GetOrCreateParallelMove(
+      (gap_pos < index) ? LGap::AFTER : LGap::BEFORE);
+}
+
+
+HBasicBlock* LAllocator::GetBlock(LifetimePosition pos) {
+  LGap* gap = chunk_->GetGapAt(chunk_->NearestGapPos(pos.InstructionIndex()));
+  return gap->block();
+}
+
+
+void LAllocator::ConnectRanges() {
+  HPhase phase("Connect ranges", this);
+  for (int i = 0; i < live_ranges()->length(); ++i) {
+    LiveRange* first_range = live_ranges()->at(i);
+    if (first_range == NULL || first_range->parent() != NULL) continue;
+
+    LiveRange* second_range = first_range->next();
+    while (second_range != NULL) {
+      LifetimePosition pos = second_range->Start();
+
+      if (!second_range->IsSpilled()) {
+        // Add gap move if the two live ranges touch and there is no block
+        // boundary.
+        if (first_range->End().Value() == pos.Value()) {
+          bool should_insert = true;
+          if (IsBlockBoundary(pos)) {
+            should_insert = CanEagerlyResolveControlFlow(GetBlock(pos));
+          }
+          if (should_insert) {
+            LParallelMove* move = GetConnectingParallelMove(pos);
+            LOperand* prev_operand = first_range->CreateAssignedOperand();
+            LOperand* cur_operand = second_range->CreateAssignedOperand();
+            move->AddMove(prev_operand, cur_operand);
+          }
+        }
+      }
+
+      first_range = second_range;
+      second_range = second_range->next();
+    }
+  }
+}
+
+
+bool LAllocator::CanEagerlyResolveControlFlow(HBasicBlock* block) const {
+  if (block->predecessors()->length() != 1) return false;
+  return block->predecessors()->first()->block_id() == block->block_id() - 1;
+}
+
+
+void LAllocator::ResolveControlFlow() {
+  HPhase phase("Resolve control flow", this);
+  const ZoneList<HBasicBlock*>* blocks = graph()->blocks();
+  for (int block_id = 1; block_id < blocks->length(); ++block_id) {
+    HBasicBlock* block = blocks->at(block_id);
+    if (CanEagerlyResolveControlFlow(block)) continue;
+    BitVector* live = live_in_sets_[block->block_id()];
+    BitVector::Iterator iterator(live);
+    while (!iterator.Done()) {
+      int operand_index = iterator.Current();
+      for (int i = 0; i < block->predecessors()->length(); ++i) {
+        HBasicBlock* cur = block->predecessors()->at(i);
+        LiveRange* cur_range = LiveRangeFor(operand_index);
+        ResolveControlFlow(cur_range, block, cur);
+      }
+      iterator.Advance();
+    }
+  }
+}
+
+
+void LAllocator::BuildLiveRanges() {
+  HPhase phase("Build live ranges", this);
+  InitializeLivenessAnalysis();
+  // Process the blocks in reverse order.
+  const ZoneList<HBasicBlock*>* blocks = graph()->blocks();
+  for (int block_id = blocks->length() - 1; block_id >= 0; --block_id) {
+    HBasicBlock* block = blocks->at(block_id);
+    BitVector* live = ComputeLiveOut(block);
+    // Initially consider all live_out values live for the entire block. We
+    // will shorten these intervals if necessary.
+    AddInitialIntervals(block, live);
+
+    // Process the instructions in reverse order, generating and killing
+    // live values.
+    ProcessInstructions(block, live);
+    // All phi output operands are killed by this block.
+    const ZoneList<HPhi*>* phis = block->phis();
+    for (int i = 0; i < phis->length(); ++i) {
+      // The live range interval already ends at the first instruction of the
+      // block.
+      HPhi* phi = phis->at(i);
+      live->Remove(phi->id());
+
+      LOperand* hint = NULL;
+      LOperand* phi_operand = NULL;
+      LGap* gap = GetLastGap(phi->block()->predecessors()->at(0));
+      LParallelMove* move = gap->GetOrCreateParallelMove(LGap::START);
+      for (int j = 0; j < move->move_operands()->length(); ++j) {
+        LOperand* to = move->move_operands()->at(j).to();
+        if (to->IsUnallocated() && to->VirtualRegister() == phi->id()) {
+          hint = move->move_operands()->at(j).from();
+          phi_operand = to;
+          break;
+        }
+      }
+      ASSERT(hint != NULL);
+
+      LifetimePosition block_start = LifetimePosition::FromInstructionIndex(
+              block->first_instruction_index());
+      Define(block_start, phi_operand, hint);
+    }
+
+    // Now live is live_in for this block except not including values live
+    // out on backward successor edges.
+    live_in_sets_[block_id] = live;
+
+    // If this block is a loop header go back and patch up the necessary
+    // predecessor blocks.
+    if (block->IsLoopHeader()) {
+      // TODO(kmillikin): Need to be able to get the last block of the loop
+      // in the loop information. Add a live range stretching from the first
+      // loop instruction to the last for each value live on entry to the
+      // header.
+      HBasicBlock* back_edge = block->loop_information()->GetLastBackEdge();
+      BitVector::Iterator iterator(live);
+      LifetimePosition start = LifetimePosition::FromInstructionIndex(
+          block->first_instruction_index());
+      LifetimePosition end = LifetimePosition::FromInstructionIndex(
+          back_edge->last_instruction_index());
+      while (!iterator.Done()) {
+        int operand_index = iterator.Current();
+        LiveRange* range = LiveRangeFor(operand_index);
+        range->EnsureInterval(start, end);
+        iterator.Advance();
+      }
+
+      for (int i = block->block_id() + 1; i <= back_edge->block_id(); ++i) {
+        live_in_sets_[i]->Union(*live);
+      }
+    }
+
+#ifdef DEBUG
+    if (block_id == 0) {
+      BitVector::Iterator iterator(live);
+      bool found = false;
+      while (!iterator.Done()) {
+        found = true;
+        int operand_index = iterator.Current();
+        PrintF("Function: %s\n",
+               *graph()->info()->function()->debug_name()->ToCString());
+        PrintF("Value %d used before first definition!\n", operand_index);
+        LiveRange* range = LiveRangeFor(operand_index);
+        PrintF("First use is at %d\n", range->first_pos()->pos().Value());
+        iterator.Advance();
+      }
+      ASSERT(!found);
+    }
+#endif
+  }
+}
+
+
+void LAllocator::AllocateGeneralRegisters() {
+  HPhase phase("Allocate general registers", this);
+  num_registers_ = Register::kNumAllocatableRegisters;
+  mode_ = CPU_REGISTERS;
+  AllocateRegisters();
+}
+
+
+bool LAllocator::SafePointsAreInOrder() const {
+  const ZoneList<LPointerMap*>* pointer_maps = chunk_->pointer_maps();
+  int safe_point = 0;
+  for (int i = 0; i < pointer_maps->length(); ++i) {
+    LPointerMap* map = pointer_maps->at(i);
+    if (safe_point > map->lithium_position()) return false;
+    safe_point = map->lithium_position();
+  }
+  return true;
+}
+
+
+void LAllocator::PopulatePointerMaps() {
+  HPhase phase("Populate pointer maps", this);
+  const ZoneList<LPointerMap*>* pointer_maps = chunk_->pointer_maps();
+
+  ASSERT(SafePointsAreInOrder());
+
+  // Iterate over all safe point positions and record a pointer
+  // for all spilled live ranges at this point.
+  int first_safe_point_index = 0;
+  int last_range_start = 0;
+  for (int range_idx = 0; range_idx < live_ranges()->length(); ++range_idx) {
+    LiveRange* range = live_ranges()->at(range_idx);
+    if (range == NULL) continue;
+    // Iterate over the first parts of multi-part live ranges.
+    if (range->parent() != NULL) continue;
+    // Skip non-pointer values.
+    if (!HasTaggedValue(range->id())) continue;
+    // Skip empty live ranges.
+    if (range->IsEmpty()) continue;
+
+    // Find the extent of the range and its children.
+    int start = range->Start().InstructionIndex();
+    int end = 0;
+    for (LiveRange* cur = range; cur != NULL; cur = cur->next()) {
+      LifetimePosition this_end = cur->End();
+      if (this_end.InstructionIndex() > end) end = this_end.InstructionIndex();
+      ASSERT(cur->Start().InstructionIndex() >= start);
+    }
+
+    // Most of the ranges are in order, but not all.  Keep an eye on when
+    // they step backwards and reset the first_safe_point_index so we don't
+    // miss any safe points.
+    if (start < last_range_start) {
+      first_safe_point_index = 0;
+    }
+    last_range_start = start;
+
+    // Step across all the safe points that are before the start of this range,
+    // recording how far we step in order to save doing this for the next range.
+    while (first_safe_point_index < pointer_maps->length()) {
+      LPointerMap* map = pointer_maps->at(first_safe_point_index);
+      int safe_point = map->lithium_position();
+      if (safe_point >= start) break;
+      first_safe_point_index++;
+    }
+
+    // Step through the safe points to see whether they are in the range.
+    for (int safe_point_index = first_safe_point_index;
+         safe_point_index < pointer_maps->length();
+         ++safe_point_index) {
+      LPointerMap* map = pointer_maps->at(safe_point_index);
+      int safe_point = map->lithium_position();
+
+      // The safe points are sorted so we can stop searching here.
+      if (safe_point - 1 > end) break;
+
+      // Advance to the next active range that covers the current
+      // safe point position.
+      LifetimePosition safe_point_pos =
+          LifetimePosition::FromInstructionIndex(safe_point);
+      LiveRange* cur = range;
+      while (cur != NULL && !cur->Covers(safe_point_pos.PrevInstruction())) {
+        cur = cur->next();
+      }
+      if (cur == NULL) continue;
+
+      // Check if the live range is spilled and the safe point is after
+      // the spill position.
+      if (range->HasAllocatedSpillOperand() &&
+          safe_point >= range->spill_start_index()) {
+        TraceAlloc("Pointer for range %d (spilled at %d) at safe point %d\n",
+                   range->id(), range->spill_start_index(), safe_point);
+        map->RecordPointer(range->GetSpillOperand());
+      }
+
+      if (!cur->IsSpilled()) {
+        TraceAlloc("Pointer in register for range %d (start at %d) "
+                   "at safe point %d\n",
+                   cur->id(), cur->Start().Value(), safe_point);
+        LOperand* operand = cur->CreateAssignedOperand();
+        ASSERT(!operand->IsStackSlot());
+        map->RecordPointer(operand);
+      }
+    }
+  }
+}
+
+
+void LAllocator::ProcessOsrEntry() {
+  const ZoneList<LInstruction*>* instrs = chunk_->instructions();
+
+  // Linear search for the OSR entry instruction in the chunk.
+  int index = -1;
+  while (++index < instrs->length() &&
+         !instrs->at(index)->IsOsrEntry()) {
+  }
+  ASSERT(index < instrs->length());
+  LOsrEntry* instruction = LOsrEntry::cast(instrs->at(index));
+
+  LifetimePosition position = LifetimePosition::FromInstructionIndex(index);
+  for (int i = 0; i < live_ranges()->length(); ++i) {
+    LiveRange* range = live_ranges()->at(i);
+    if (range != NULL) {
+      if (range->Covers(position) &&
+          range->HasRegisterAssigned() &&
+          range->TopLevel()->HasAllocatedSpillOperand()) {
+        int reg_index = range->assigned_register();
+        LOperand* spill_operand = range->TopLevel()->GetSpillOperand();
+        if (range->IsDouble()) {
+          instruction->MarkSpilledDoubleRegister(reg_index, spill_operand);
+        } else {
+          instruction->MarkSpilledRegister(reg_index, spill_operand);
+        }
+      }
+    }
+  }
+}
+
+
+void LAllocator::AllocateDoubleRegisters() {
+  HPhase phase("Allocate double registers", this);
+  num_registers_ = DoubleRegister::kNumAllocatableRegisters;
+  mode_ = XMM_REGISTERS;
+  AllocateRegisters();
+}
+
+
+void LAllocator::AllocateRegisters() {
+  ASSERT(mode_ != NONE);
+  reusable_slots_.Clear();
+
+  for (int i = 0; i < live_ranges_.length(); ++i) {
+    if (live_ranges_[i] != NULL) {
+      if (HasDoubleValue(live_ranges_[i]->id()) == (mode_ == XMM_REGISTERS)) {
+        AddToUnhandledUnsorted(live_ranges_[i]);
+      }
+    }
+  }
+  SortUnhandled();
+  ASSERT(UnhandledIsSorted());
+
+  ASSERT(active_live_ranges_.is_empty());
+  ASSERT(inactive_live_ranges_.is_empty());
+
+  if (mode_ == XMM_REGISTERS) {
+    for (int i = 0; i < fixed_double_live_ranges_.length(); ++i) {
+      LiveRange* current = fixed_double_live_ranges_.at(i);
+      if (current != NULL) {
+        AddToInactive(current);
+      }
+    }
+  } else {
+    for (int i = 0; i < fixed_live_ranges_.length(); ++i) {
+      LiveRange* current = fixed_live_ranges_.at(i);
+      if (current != NULL) {
+        AddToInactive(current);
+      }
+    }
+  }
+
+  while (!unhandled_live_ranges_.is_empty()) {
+    ASSERT(UnhandledIsSorted());
+    LiveRange* current = unhandled_live_ranges_.RemoveLast();
+    ASSERT(UnhandledIsSorted());
+    LifetimePosition position = current->Start();
+    TraceAlloc("Processing interval %d start=%d\n",
+               current->id(),
+               position.Value());
+
+    if (current->HasAllocatedSpillOperand()) {
+      TraceAlloc("Live range %d already has a spill operand\n", current->id());
+      LifetimePosition next_pos = position;
+      if (chunk_->IsGapAt(next_pos.InstructionIndex())) {
+        next_pos = next_pos.NextInstruction();
+      }
+      UsePosition* pos = current->NextUsePositionRegisterIsBeneficial(next_pos);
+      // If the range already has a spill operand and it doesn't need a
+      // register immediately, split it and spill the first part of the range.
+      if (pos == NULL) {
+        Spill(current);
+        continue;
+      } else if (pos->pos().Value() >
+                 current->Start().NextInstruction().Value()) {
+        // Do not spill live range eagerly if use position that can benefit from
+        // the register is too close to the start of live range.
+        LiveRange* part = Split(current,
+                                current->Start().NextInstruction(),
+                                pos->pos());
+        Spill(current);
+        AddToUnhandledSorted(part);
+        ASSERT(UnhandledIsSorted());
+        continue;
+      }
+    }
+
+    for (int i = 0; i < active_live_ranges_.length(); ++i) {
+      LiveRange* cur_active = active_live_ranges_.at(i);
+      if (cur_active->End().Value() <= position.Value()) {
+        ActiveToHandled(cur_active);
+        --i;  // The live range was removed from the list of active live ranges.
+      } else if (!cur_active->Covers(position)) {
+        ActiveToInactive(cur_active);
+        --i;  // The live range was removed from the list of active live ranges.
+      }
+    }
+
+    for (int i = 0; i < inactive_live_ranges_.length(); ++i) {
+      LiveRange* cur_inactive = inactive_live_ranges_.at(i);
+      if (cur_inactive->End().Value() <= position.Value()) {
+        InactiveToHandled(cur_inactive);
+        --i;  // Live range was removed from the list of inactive live ranges.
+      } else if (cur_inactive->Covers(position)) {
+        InactiveToActive(cur_inactive);
+        --i;  // Live range was removed from the list of inactive live ranges.
+      }
+    }
+
+    ASSERT(!current->HasRegisterAssigned() && !current->IsSpilled());
+
+    bool result = TryAllocateFreeReg(current);
+    if (!result) {
+      AllocateBlockedReg(current);
+    }
+
+    if (current->HasRegisterAssigned()) {
+      AddToActive(current);
+    }
+  }
+
+  active_live_ranges_.Clear();
+  inactive_live_ranges_.Clear();
+}
+
+
+void LAllocator::Setup() {
+  LConstantOperand::SetupCache();
+  LStackSlot::SetupCache();
+  LDoubleStackSlot::SetupCache();
+  LRegister::SetupCache();
+  LDoubleRegister::SetupCache();
+}
+
+
+void LAllocator::TraceAlloc(const char* msg, ...) {
+  if (FLAG_trace_alloc) {
+    va_list arguments;
+    va_start(arguments, msg);
+    OS::VPrint(msg, arguments);
+    va_end(arguments);
+  }
+}
+
+
+void LAllocator::RecordUse(HValue* value, LUnallocated* operand) {
+  operand->set_virtual_register(value->id());
+  current_summary()->AddInput(operand);
+}
+
+
+bool LAllocator::HasTaggedValue(int virtual_register) const {
+  HValue* value = graph()->LookupValue(virtual_register);
+  if (value == NULL) return false;
+  return value->representation().IsTagged();
+}
+
+
+bool LAllocator::HasDoubleValue(int virtual_register) const {
+  HValue* value = graph()->LookupValue(virtual_register);
+  if (value == NULL) return false;
+  return value->representation().IsDouble();
+}
+
+
+void LAllocator::MarkAsCall() {
+  current_summary()->MarkAsCall();
+}
+
+
+void LAllocator::RecordDefinition(HInstruction* instr, LUnallocated* operand) {
+  operand->set_virtual_register(instr->id());
+  current_summary()->SetOutput(operand);
+}
+
+
+void LAllocator::RecordTemporary(LUnallocated* operand) {
+  ASSERT(next_virtual_register_ < LUnallocated::kMaxVirtualRegisters);
+  if (!operand->HasFixedPolicy()) {
+    operand->set_virtual_register(next_virtual_register_++);
+  }
+  current_summary()->AddTemp(operand);
+}
+
+
+int LAllocator::max_initial_value_ids() {
+  return LUnallocated::kMaxVirtualRegisters / 32;
+}
+
+
+void LAllocator::BeginInstruction() {
+  if (next_summary_ == NULL) {
+    next_summary_ = new InstructionSummary();
+  }
+  summary_stack_.Add(next_summary_);
+  next_summary_ = NULL;
+}
+
+
+void LAllocator::SummarizeInstruction(int index) {
+  InstructionSummary* sum = summary_stack_.RemoveLast();
+  if (summaries_.length() <= index) {
+    summaries_.AddBlock(NULL, index + 1 - summaries_.length());
+  }
+  ASSERT(summaries_[index] == NULL);
+  if (sum->Output() != NULL || sum->InputCount() > 0 || sum->TempCount() > 0) {
+    summaries_[index] = sum;
+  } else {
+    next_summary_ = sum;
+  }
+}
+
+
+void LAllocator::OmitInstruction() {
+  summary_stack_.RemoveLast();
+}
+
+
+void LAllocator::AddToActive(LiveRange* range) {
+  TraceAlloc("Add live range %d to active\n", range->id());
+  active_live_ranges_.Add(range);
+}
+
+
+void LAllocator::AddToInactive(LiveRange* range) {
+  TraceAlloc("Add live range %d to inactive\n", range->id());
+  inactive_live_ranges_.Add(range);
+}
+
+
+void LAllocator::AddToUnhandledSorted(LiveRange* range) {
+  if (range == NULL || range->IsEmpty()) return;
+  ASSERT(!range->HasRegisterAssigned() && !range->IsSpilled());
+  for (int i = unhandled_live_ranges_.length() - 1; i >= 0; --i) {
+    LiveRange* cur_range = unhandled_live_ranges_.at(i);
+    if (range->ShouldBeAllocatedBefore(cur_range)) {
+      TraceAlloc("Add live range %d to unhandled at %d\n", range->id(), i + 1);
+      unhandled_live_ranges_.InsertAt(i + 1, range);
+      ASSERT(UnhandledIsSorted());
+      return;
+    }
+  }
+  TraceAlloc("Add live range %d to unhandled at start\n", range->id());
+  unhandled_live_ranges_.InsertAt(0, range);
+  ASSERT(UnhandledIsSorted());
+}
+
+
+void LAllocator::AddToUnhandledUnsorted(LiveRange* range) {
+  if (range == NULL || range->IsEmpty()) return;
+  ASSERT(!range->HasRegisterAssigned() && !range->IsSpilled());
+  TraceAlloc("Add live range %d to unhandled unsorted at end\n", range->id());
+  unhandled_live_ranges_.Add(range);
+}
+
+
+static int UnhandledSortHelper(LiveRange* const* a, LiveRange* const* b) {
+  ASSERT(!(*a)->ShouldBeAllocatedBefore(*b) ||
+         !(*b)->ShouldBeAllocatedBefore(*a));
+  if ((*a)->ShouldBeAllocatedBefore(*b)) return 1;
+  if ((*b)->ShouldBeAllocatedBefore(*a)) return -1;
+  return (*a)->id() - (*b)->id();
+}
+
+
+// Sort the unhandled live ranges so that the ranges to be processed first are
+// at the end of the array list.  This is convenient for the register allocation
+// algorithm because it is efficient to remove elements from the end.
+void LAllocator::SortUnhandled() {
+  TraceAlloc("Sort unhandled\n");
+  unhandled_live_ranges_.Sort(&UnhandledSortHelper);
+}
+
+
+bool LAllocator::UnhandledIsSorted() {
+  int len = unhandled_live_ranges_.length();
+  for (int i = 1; i < len; i++) {
+    LiveRange* a = unhandled_live_ranges_.at(i - 1);
+    LiveRange* b = unhandled_live_ranges_.at(i);
+    if (a->Start().Value() < b->Start().Value()) return false;
+  }
+  return true;
+}
+
+
+void LAllocator::FreeSpillSlot(LiveRange* range) {
+  // Check that we are the last range.
+  if (range->next() != NULL) return;
+
+  if (!range->TopLevel()->HasAllocatedSpillOperand()) return;
+
+  int index = range->TopLevel()->GetSpillOperand()->index();
+  if (index >= 0) {
+    reusable_slots_.Add(range);
+  }
+}
+
+
+LOperand* LAllocator::TryReuseSpillSlot(LiveRange* range) {
+  if (reusable_slots_.is_empty()) return NULL;
+  if (reusable_slots_.first()->End().Value() >
+      range->TopLevel()->Start().Value()) {
+    return NULL;
+  }
+  LOperand* result = reusable_slots_.first()->TopLevel()->GetSpillOperand();
+  reusable_slots_.Remove(0);
+  return result;
+}
+
+
+void LAllocator::ActiveToHandled(LiveRange* range) {
+  ASSERT(active_live_ranges_.Contains(range));
+  active_live_ranges_.RemoveElement(range);
+  TraceAlloc("Moving live range %d from active to handled\n", range->id());
+  FreeSpillSlot(range);
+}
+
+
+void LAllocator::ActiveToInactive(LiveRange* range) {
+  ASSERT(active_live_ranges_.Contains(range));
+  active_live_ranges_.RemoveElement(range);
+  inactive_live_ranges_.Add(range);
+  TraceAlloc("Moving live range %d from active to inactive\n", range->id());
+}
+
+
+void LAllocator::InactiveToHandled(LiveRange* range) {
+  ASSERT(inactive_live_ranges_.Contains(range));
+  inactive_live_ranges_.RemoveElement(range);
+  TraceAlloc("Moving live range %d from inactive to handled\n", range->id());
+  FreeSpillSlot(range);
+}
+
+
+void LAllocator::InactiveToActive(LiveRange* range) {
+  ASSERT(inactive_live_ranges_.Contains(range));
+  inactive_live_ranges_.RemoveElement(range);
+  active_live_ranges_.Add(range);
+  TraceAlloc("Moving live range %d from inactive to active\n", range->id());
+}
+
+
+bool LAllocator::TryAllocateFreeReg(LiveRange* current) {
+  LifetimePosition max_pos = LifetimePosition::FromInstructionIndex(
+      chunk_->instructions()->length() + 1);
+  ASSERT(DoubleRegister::kNumAllocatableRegisters >=
+         Register::kNumAllocatableRegisters);
+  EmbeddedVector<LifetimePosition, DoubleRegister::kNumAllocatableRegisters>
+      free_pos(max_pos);
+  for (int i = 0; i < active_live_ranges_.length(); ++i) {
+    LiveRange* cur_active = active_live_ranges_.at(i);
+    free_pos[cur_active->assigned_register()] =
+        LifetimePosition::FromInstructionIndex(0);
+  }
+
+  for (int i = 0; i < inactive_live_ranges_.length(); ++i) {
+    LiveRange* cur_inactive = inactive_live_ranges_.at(i);
+    ASSERT(cur_inactive->End().Value() > current->Start().Value());
+    LifetimePosition next_intersection =
+        cur_inactive->FirstIntersection(current);
+    if (!next_intersection.IsValid()) continue;
+    int cur_reg = cur_inactive->assigned_register();
+    free_pos[cur_reg] = Min(free_pos[cur_reg], next_intersection);
+  }
+
+  UsePosition* pos = current->FirstPosWithHint();
+  if (pos != NULL) {
+    LOperand* hint = pos->hint();
+    if (hint->IsRegister() || hint->IsDoubleRegister()) {
+      int register_index = hint->index();
+      TraceAlloc("Found reg hint %d for live range %d (free [%d, end %d[)\n",
+                 register_index,
+                 current->id(),
+                 free_pos[register_index].Value(),
+                 current->End().Value());
+      if (free_pos[register_index].Value() >= current->End().Value()) {
+        TraceAlloc("Assigning preferred reg %d to live range %d\n",
+                   register_index,
+                   current->id());
+        current->set_assigned_register(register_index, mode_ == XMM_REGISTERS);
+        return true;
+      }
+    }
+  }
+
+  int max_reg = 0;
+  for (int i = 1; i < RegisterCount(); ++i) {
+    if (free_pos[i].Value() > free_pos[max_reg].Value()) {
+      max_reg = i;
+    }
+  }
+
+  if (free_pos[max_reg].InstructionIndex() == 0) {
+    return false;
+  } else if (free_pos[max_reg].Value() >= current->End().Value()) {
+    TraceAlloc("Assigning reg %d to live range %d\n", max_reg, current->id());
+    current->set_assigned_register(max_reg, mode_ == XMM_REGISTERS);
+  } else {
+    // Split the interval at the nearest gap and never split an interval at its
+    // start position.
+    LifetimePosition pos =
+        LifetimePosition::FromInstructionIndex(
+            chunk_->NearestGapPos(free_pos[max_reg].InstructionIndex()));
+    if (pos.Value() <= current->Start().Value()) return false;
+    LiveRange* second_range = Split(current, pos);
+    AddToUnhandledSorted(second_range);
+    current->set_assigned_register(max_reg, mode_ == XMM_REGISTERS);
+  }
+
+  return true;
+}
+
+
+void LAllocator::AllocateBlockedReg(LiveRange* current) {
+  LifetimePosition max_pos =
+      LifetimePosition::FromInstructionIndex(
+          chunk_->instructions()->length() + 1);
+  ASSERT(DoubleRegister::kNumAllocatableRegisters >=
+         Register::kNumAllocatableRegisters);
+  EmbeddedVector<LifetimePosition, DoubleRegister::kNumAllocatableRegisters>
+      use_pos(max_pos);
+  EmbeddedVector<LifetimePosition, DoubleRegister::kNumAllocatableRegisters>
+      block_pos(max_pos);
+
+  for (int i = 0; i < active_live_ranges_.length(); ++i) {
+    LiveRange* range = active_live_ranges_[i];
+    int cur_reg = range->assigned_register();
+    if (range->IsFixed() || !range->CanBeSpilled(current->Start())) {
+      block_pos[cur_reg] = use_pos[cur_reg] =
+          LifetimePosition::FromInstructionIndex(0);
+    } else {
+      UsePosition* next_use = range->NextUsePositionRegisterIsBeneficial(
+          current->Start());
+      if (next_use == NULL) {
+        use_pos[cur_reg] = range->End();
+      } else {
+        use_pos[cur_reg] = next_use->pos();
+      }
+    }
+  }
+
+  for (int i = 0; i < inactive_live_ranges_.length(); ++i) {
+    LiveRange* range = inactive_live_ranges_.at(i);
+    ASSERT(range->End().Value() > current->Start().Value());
+    LifetimePosition next_intersection = range->FirstIntersection(current);
+    if (!next_intersection.IsValid()) continue;
+    int cur_reg = range->assigned_register();
+    if (range->IsFixed()) {
+      block_pos[cur_reg] = Min(block_pos[cur_reg], next_intersection);
+      use_pos[cur_reg] = Min(block_pos[cur_reg], use_pos[cur_reg]);
+    } else {
+      use_pos[cur_reg] = Min(use_pos[cur_reg], next_intersection);
+    }
+  }
+
+  int max_reg = 0;
+  for (int i = 1; i < RegisterCount(); ++i) {
+    if (use_pos[i].Value() > use_pos[max_reg].Value()) {
+      max_reg = i;
+    }
+  }
+
+  UsePosition* first_usage = current->NextRegisterPosition(current->Start());
+  if (first_usage == NULL) {
+    Spill(current);
+  } else if (use_pos[max_reg].Value() < first_usage->pos().Value()) {
+    SplitAndSpill(current, current->Start(), first_usage->pos());
+  } else {
+    if (block_pos[max_reg].Value() < current->End().Value()) {
+      // Split current before blocked position.
+      LiveRange* second_range = Split(current,
+                                      current->Start(),
+                                      block_pos[max_reg]);
+      AddToUnhandledSorted(second_range);
+    }
+
+    current->set_assigned_register(max_reg, mode_ == XMM_REGISTERS);
+    SplitAndSpillIntersecting(current);
+  }
+}
+
+
+void LAllocator::SplitAndSpillIntersecting(LiveRange* current) {
+  ASSERT(current->HasRegisterAssigned());
+  int reg = current->assigned_register();
+  LifetimePosition split_pos =
+      LifetimePosition::FromInstructionIndex(
+          chunk_->NearestGapPos(current->Start().InstructionIndex()));
+  for (int i = 0; i < active_live_ranges_.length(); ++i) {
+    LiveRange* range = active_live_ranges_[i];
+    if (range->assigned_register() == reg) {
+      UsePosition* next_pos = range->NextRegisterPosition(current->Start());
+      if (next_pos == NULL) {
+        SplitAndSpill(range, split_pos);
+      } else {
+        SplitAndSpill(range, split_pos, next_pos->pos());
+      }
+      ActiveToHandled(range);
+      --i;
+    }
+  }
+
+  for (int i = 0; i < inactive_live_ranges_.length(); ++i) {
+    LiveRange* range = inactive_live_ranges_[i];
+    ASSERT(range->End().Value() > current->Start().Value());
+    if (range->assigned_register() == reg && !range->IsFixed()) {
+      LifetimePosition next_intersection = range->FirstIntersection(current);
+      if (next_intersection.IsValid()) {
+        UsePosition* next_pos = range->NextRegisterPosition(current->Start());
+        if (next_pos == NULL) {
+          SplitAndSpill(range, split_pos);
+        } else {
+          next_intersection = Min(next_intersection, next_pos->pos());
+          SplitAndSpill(range, split_pos, next_intersection);
+        }
+        InactiveToHandled(range);
+        --i;
+      }
+    }
+  }
+}
+
+
+LiveRange* LAllocator::Split(LiveRange* range,
+                             LifetimePosition start,
+                             LifetimePosition end) {
+  ASSERT(!range->IsFixed());
+  TraceAlloc("Splitting live range %d in position between [%d, %d[\n",
+             range->id(),
+             start.Value(),
+             end.Value());
+
+  LifetimePosition split_pos = FindOptimalSplitPos(
+      start, end.PrevInstruction().InstructionEnd());
+  ASSERT(split_pos.Value() >= start.Value());
+  return Split(range, split_pos);
+}
+
+
+LifetimePosition LAllocator::FindOptimalSplitPos(LifetimePosition start,
+                                                 LifetimePosition end) {
+  int start_instr = start.InstructionIndex();
+  int end_instr = end.InstructionIndex();
+  ASSERT(start_instr <= end_instr);
+
+  // We have no choice
+  if (start_instr == end_instr) return end;
+
+  HBasicBlock* end_block = GetBlock(start);
+  HBasicBlock* start_block = GetBlock(end);
+
+  if (end_block == start_block) {
+    // The interval is split in the same basic block. Split at latest possible
+    // position.
+    return end;
+  }
+
+  HBasicBlock* block = end_block;
+  // Move to the most outside loop header.
+  while (block->parent_loop_header() != NULL &&
+      block->parent_loop_header()->block_id() > start_block->block_id()) {
+    block = block->parent_loop_header();
+  }
+
+  if (block == end_block) {
+    return end;
+  }
+
+  return LifetimePosition::FromInstructionIndex(
+      block->first_instruction_index());
+}
+
+
+bool LAllocator::IsBlockBoundary(LifetimePosition pos) {
+  return pos.IsInstructionStart() &&
+      chunk_->instructions()->at(pos.InstructionIndex())->IsLabel();
+}
+
+
+void LAllocator::AddGapMove(int pos, LiveRange* prev, LiveRange* next) {
+  UsePosition* prev_pos = prev->AddUsePosition(
+      LifetimePosition::FromInstructionIndex(pos));
+  UsePosition* next_pos = next->AddUsePosition(
+      LifetimePosition::FromInstructionIndex(pos));
+  LOperand* prev_operand = prev_pos->operand();
+  LOperand* next_operand = next_pos->operand();
+  LGap* gap = chunk_->GetGapAt(pos);
+  gap->GetOrCreateParallelMove(LGap::START)->
+      AddMove(prev_operand, next_operand);
+  next_pos->set_hint(prev_operand);
+}
+
+
+LiveRange* LAllocator::Split(LiveRange* range, LifetimePosition pos) {
+  ASSERT(!range->IsFixed());
+  TraceAlloc("Splitting live range %d at %d\n", range->id(), pos.Value());
+  if (pos.Value() <= range->Start().Value()) {
+    return range;
+  }
+  LiveRange* result = LiveRangeFor(next_virtual_register_++);
+  range->SplitAt(pos, result);
+  return result;
+}
+
+
+void LAllocator::SplitAndSpill(LiveRange* range,
+                               LifetimePosition start,
+                               LifetimePosition end) {
+  // We have an interval range and want to make sure that it is
+  // spilled at start and at most spilled until end.
+  ASSERT(start.Value() < end.Value());
+  LiveRange* tail_part = Split(range, start);
+  if (tail_part->Start().Value() < end.Value()) {
+    LiveRange* third_part = Split(tail_part,
+                                  tail_part->Start().NextInstruction(),
+                                  end);
+    Spill(tail_part);
+    ASSERT(third_part != tail_part);
+    AddToUnhandledSorted(third_part);
+  } else {
+    AddToUnhandledSorted(tail_part);
+  }
+}
+
+
+void LAllocator::SplitAndSpill(LiveRange* range, LifetimePosition at) {
+  at = LifetimePosition::FromInstructionIndex(
+      chunk_->NearestGapPos(at.InstructionIndex()));
+  LiveRange* second_part = Split(range, at);
+  Spill(second_part);
+}
+
+
+void LAllocator::Spill(LiveRange* range) {
+  ASSERT(!range->IsSpilled());
+  TraceAlloc("Spilling live range %d\n", range->id());
+  LiveRange* first = range->TopLevel();
+
+  if (!first->HasAllocatedSpillOperand()) {
+    LOperand* op = TryReuseSpillSlot(range);
+    if (op == NULL) op = chunk_->GetNextSpillSlot(mode_ == XMM_REGISTERS);
+    first->SetSpillOperand(op);
+  }
+  range->MakeSpilled();
+}
+
+
+int LAllocator::RegisterCount() const {
+  return num_registers_;
+}
+
+
+#ifdef DEBUG
+
+
+void LAllocator::Verify() const {
+  for (int i = 0; i < live_ranges()->length(); ++i) {
+    LiveRange* current = live_ranges()->at(i);
+    if (current != NULL) current->Verify();
+  }
+}
+
+
+#endif
+
+
+} }  // namespace v8::internal