Version 3.0.2.

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
@@ skipping 229 matching lines @@
   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 (IsDouble()) {
+    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);
@@ skipping 22 matching lines @@
   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(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;
     }
@@ skipping 314 matching lines @@
 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, GENERAL_REGISTERS);
+    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, DOUBLE_REGISTERS);
+    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];
@@ skipping 595 matching lines @@
         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;
 }
@@ skipping 111 matching lines @@
           instruction->MarkSpilledDoubleRegister(reg_index, spill_operand);
         } else {
           instruction->MarkSpilledRegister(reg_index, spill_operand);
         }
       }
     }
   }
 }
 
 
-void LAllocator::AllocateGeneralRegisters() {
-  HPhase phase("Allocate general registers", this);
-  num_registers_ = Register::kNumAllocatableRegisters;
-  mode_ = GENERAL_REGISTERS;
-  AllocateRegisters();
-}
-
-
 void LAllocator::AllocateDoubleRegisters() {
   HPhase phase("Allocate double registers", this);
   num_registers_ = DoubleRegister::kNumAllocatableRegisters;
-  mode_ = DOUBLE_REGISTERS;
+  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 (RequiredRegisterKind(live_ranges_[i]->id()) == mode_) {
+      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_ == DOUBLE_REGISTERS) {
+  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) {
@@ skipping 20 matching lines @@
       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.
-        SpillBetween(current, current->Start(), pos->pos());
+        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.
@@ skipping 33 matching lines @@
 
 void LAllocator::Setup() {
   LConstantOperand::SetupCache();
   LStackSlot::SetupCache();
   LDoubleStackSlot::SetupCache();
   LRegister::SetupCache();
   LDoubleRegister::SetupCache();
 }
 
 
-const char* LAllocator::RegisterName(int allocation_index) {
-  ASSERT(mode_ != NONE);
-  if (mode_ == GENERAL_REGISTERS) {
-    return Register::AllocationIndexToString(allocation_index);
-  } else {
-    return DoubleRegister::AllocationIndexToString(allocation_index);
-  }
-}
-
-
 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();
 }
 
 
-RegisterKind LAllocator::RequiredRegisterKind(int virtual_register) const {
+bool LAllocator::HasDoubleValue(int virtual_register) const {
   HValue* value = graph()->LookupValue(virtual_register);
-  if (value != NULL && value->representation().IsDouble()) {
-    return DOUBLE_REGISTERS;
-  }
-  return GENERAL_REGISTERS;
+  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());
@@ skipping 160 matching lines @@
 
 
 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());
 }
 
 
-// TryAllocateFreeReg and AllocateBlockedReg assume this
-// when allocating local arrays.
-STATIC_ASSERT(DoubleRegister::kNumAllocatableRegisters >=
-              Register::kNumAllocatableRegisters);
-
-
 bool LAllocator::TryAllocateFreeReg(LiveRange* current) {
-  LifetimePosition free_until_pos[DoubleRegister::kNumAllocatableRegisters];
-
-  for (int i = 0; i < DoubleRegister::kNumAllocatableRegisters; i++) {
-    free_until_pos[i] = LifetimePosition::MaxPosition();
-  }
-
+  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_until_pos[cur_active->assigned_register()] =
+    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_until_pos[cur_reg] = Min(free_until_pos[cur_reg], next_intersection);
+    free_pos[cur_reg] = Min(free_pos[cur_reg], next_intersection);
   }
 
-  UsePosition* hinted_use = current->FirstPosWithHint();
-  if (hinted_use != NULL) {
-    LOperand* hint = hinted_use->hint();
+  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 %s (free until [%d) for live range %d (end %d[).\n",
-          RegisterName(register_index),
-          free_until_pos[register_index].Value(),
-          current->id(),
-          current->End().Value());
-
-      // The desired register is free until the end of the current live range.
-      if (free_until_pos[register_index].Value() >= current->End().Value()) {
-        TraceAlloc("Assigning preferred reg %s to live range %d\n",
-                   RegisterName(register_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_);
+        current->set_assigned_register(register_index, mode_ == XMM_REGISTERS);
         return true;
       }
     }
   }
 
-  // Find the register which stays free for the longest time.
-  int reg = 0;
+  int max_reg = 0;
   for (int i = 1; i < RegisterCount(); ++i) {
-    if (free_until_pos[i].Value() > free_until_pos[reg].Value()) {
-      reg = i;
+    if (free_pos[i].Value() > free_pos[max_reg].Value()) {
+      max_reg = i;
     }
   }
 
-  LifetimePosition pos = free_until_pos[reg];
-
-  if (pos.Value() <= current->Start().Value()) {
-    // All registers are blocked.
+  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);
   }
 
-  if (pos.Value() < current->End().Value()) {
-    // Register reg is available at the range start but becomes blocked before
-    // the range end. Split current at position where it becomes blocked.
-    LiveRange* tail = SplitAt(current, pos);
-    AddToUnhandledSorted(tail);
-  }
-
-
-  // Register reg is available at the range start and is free until
-  // the range end.
-  ASSERT(pos.Value() >= current->End().Value());
-  TraceAlloc("Assigning reg %s to live range %d\n",
-             RegisterName(reg),
-             current->id());
-  current->set_assigned_register(reg, mode_);
-
   return true;
 }
 
 
 void LAllocator::AllocateBlockedReg(LiveRange* current) {
-  UsePosition* register_use = current->NextRegisterPosition(current->Start());
-  if (register_use == NULL) {
-    // There is no use in the current live range that requires a register.
-    // We can just spill it.
-    Spill(current);
-    return;
-  }
-
-
-  LifetimePosition use_pos[DoubleRegister::kNumAllocatableRegisters];
-  LifetimePosition block_pos[DoubleRegister::kNumAllocatableRegisters];
-
-  for (int i = 0; i < DoubleRegister::kNumAllocatableRegisters; i++) {
-    use_pos[i] = block_pos[i] = LifetimePosition::MaxPosition();
-  }
+  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());
@@ skipping 12 matching lines @@
     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 reg = 0;
+  int max_reg = 0;
   for (int i = 1; i < RegisterCount(); ++i) {
-    if (use_pos[i].Value() > use_pos[reg].Value()) {
-      reg = i;
+    if (use_pos[i].Value() > use_pos[max_reg].Value()) {
+      max_reg = i;
     }
   }
 
-  LifetimePosition pos = use_pos[reg];
+  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);
+    }
 
-  if (pos.Value() < register_use->pos().Value()) {
-    // All registers are blocked before the first use that requires a register.
-    // Spill starting part of live range up to that use.
-    //
-    // Corner case: the first use position is equal to the start of the range.
-    // In this case we have nothing to spill and SpillBetween will just return
-    // this range to the list of unhandled ones. This will lead to the infinite
-    // loop.
-    ASSERT(current->Start().Value() < register_use->pos().Value());
-    SpillBetween(current, current->Start(), register_use->pos());
-    return;
+    current->set_assigned_register(max_reg, mode_ == XMM_REGISTERS);
+    SplitAndSpillIntersecting(current);
   }
-
-  if (block_pos[reg].Value() < current->End().Value()) {
-    // Register becomes blocked before the current range end. Split before that
-    // position.
-    LiveRange* tail = SplitBetween(current,
-                                   current->Start(),
-                                   block_pos[reg].InstructionStart());
-    AddToUnhandledSorted(tail);
-  }
-
-  // Register reg is not blocked for the whole range.
-  ASSERT(block_pos[reg].Value() >= current->End().Value());
-  TraceAlloc("Assigning reg %s to live range %d\n",
-             RegisterName(reg),
-             current->id());
-  current->set_assigned_register(reg, mode_);
-
-  // This register was not free. Thus we need to find and spill
-  // parts of active and inactive live regions that use the same register
-  // at the same lifetime positions as current.
-  SplitAndSpillIntersecting(current);
 }
 
 
 void LAllocator::SplitAndSpillIntersecting(LiveRange* current) {
   ASSERT(current->HasRegisterAssigned());
   int reg = current->assigned_register();
-  LifetimePosition split_pos = current->Start();
+  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) {
-        SpillAfter(range, split_pos);
+        SplitAndSpill(range, split_pos);
       } else {
-        SpillBetween(range, split_pos, next_pos->pos());
+        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) {
-          SpillAfter(range, split_pos);
+          SplitAndSpill(range, split_pos);
         } else {
           next_intersection = Min(next_intersection, next_pos->pos());
-          SpillBetween(range, split_pos, next_intersection);
+          SplitAndSpill(range, split_pos, next_intersection);
         }
         InactiveToHandled(range);
         --i;
       }
     }
   }
 }
 
 
-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::SplitAt(LiveRange* range, LifetimePosition pos) {
+LiveRange* LAllocator::Split(LiveRange* range,
+                             LifetimePosition start,
+                             LifetimePosition end) {
   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;
-}
-
-
-LiveRange* LAllocator::SplitBetween(LiveRange* range,
-                                    LifetimePosition start,
-                                    LifetimePosition end) {
-  ASSERT(!range->IsFixed());
-  TraceAlloc("Splitting live range %d in position between [%d, %d]\n",
+  TraceAlloc("Splitting live range %d in position between [%d, %d[\n",
              range->id(),
              start.Value(),
              end.Value());
 
-  LifetimePosition split_pos = FindOptimalSplitPos(start, end);
+  LifetimePosition split_pos = FindOptimalSplitPos(
+      start, end.PrevInstruction().InstructionEnd());
   ASSERT(split_pos.Value() >= start.Value());
-  return SplitAt(range, split_pos);
+  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;
-  // Find header of outermost loop.
+  // 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;
+  if (block == end_block) {
+    return end;
+  }
 
   return LifetimePosition::FromInstructionIndex(
       block->first_instruction_index());
 }
 
 
-void LAllocator::SpillAfter(LiveRange* range, LifetimePosition pos) {
-  LiveRange* second_part = SplitAt(range, pos);
-  Spill(second_part);
+bool LAllocator::IsBlockBoundary(LifetimePosition pos) {
+  return pos.IsInstructionStart() &&
+      chunk_->instructions()->at(pos.InstructionIndex())->IsLabel();
 }
 
 
-void LAllocator::SpillBetween(LiveRange* range,
-                              LifetimePosition start,
-                              LifetimePosition end) {
+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* second_part = SplitAt(range, start);
-
-  if (second_part->Start().Value() < end.Value()) {
-    // The split result intersects with [start, end[.
-    // Split it at position between ]start+1, end[, spill the middle part
-    // and put the rest to unhandled.
-    LiveRange* third_part = SplitBetween(
-        second_part,
-        second_part->Start().InstructionEnd(),
-        end.PrevInstruction().InstructionEnd());
-
-    ASSERT(third_part != second_part);
-
-    Spill(second_part);
+  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 {
-    // The split result does not intersect with [start, end[.
-    // Nothing to spill. Just put it to unhandled as whole.
-    AddToUnhandledSorted(second_part);
+    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_ == DOUBLE_REGISTERS);
+    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