[turbofan] removed some dead code.

src/compiler/register-allocator.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/base/adapters.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/register-allocator.h"
 #include "src/string-stream.h"
 
 namespace v8 {
@@ skipping 417 matching lines @@
 
 
 LiveRange* LiveRange::SplitAt(LifetimePosition position, Zone* zone) {
   int new_id = TopLevel()->GetNextChildId();
   LiveRange* child = new (zone) LiveRange(new_id, representation(), TopLevel());
   DetachAt(position, child, zone);
 
   child->top_level_ = TopLevel();
   child->next_ = next_;
   next_ = child;
-  if (child->next() == nullptr) {
-    TopLevel()->set_last_child(child);
-  }
   return child;
 }
 
 
 UsePosition* LiveRange::DetachAt(LifetimePosition position, LiveRange* result,
                                  Zone* zone) {
   DCHECK(Start() < position);
   DCHECK(End() > position);
   DCHECK(result->IsEmpty());
   // Find the last interval that ends before the position. If the
@@ skipping 76 matching lines @@
   size_ = kInvalidSize;
   weight_ = kInvalidWeight;
 #ifdef DEBUG
   Verify();
   result->Verify();
 #endif
   return use_before;
 }
 
 
-void LiveRange::AppendAsChild(TopLevelLiveRange* other) {
-  next_ = other;
-
-  other->UpdateParentForAllChildren(TopLevel());
-  TopLevel()->UpdateSpillRangePostMerge(other);
-  TopLevel()->set_last_child(other->last_child());
-}
-
-
 void LiveRange::UpdateParentForAllChildren(TopLevelLiveRange* new_top_level) {
   LiveRange* child = this;
   for (; child != nullptr; child = child->next()) {
     child->top_level_ = new_top_level;
   }
 }
 
 
 void LiveRange::ConvertUsesToOperand(const InstructionOperand& op,
                                      const InstructionOperand& spill_op) {
@@ skipping 120 matching lines @@
 
 TopLevelLiveRange::TopLevelLiveRange(int vreg, MachineRepresentation rep)
     : LiveRange(0, rep, this),
       vreg_(vreg),
       last_child_id_(0),
       splintered_from_(nullptr),
       spill_operand_(nullptr),
       spill_move_insertion_locations_(nullptr),
       spilled_in_deferred_blocks_(false),
       spill_start_index_(kMaxInt),
-      last_child_(this),
       last_pos_(nullptr),
       splinter_(nullptr),
       has_preassigned_slot_(false) {
   bits_ |= SpillTypeField::encode(SpillType::kNoSpillType);
 }
 
 
 #if DEBUG
 int TopLevelLiveRange::debug_virt_reg() const {
   return IsSplinter() ? splintered_from()->vreg() : vreg();
@@ skipping 2752 matching lines @@
     auto eliminate = moves->PrepareInsertAfter(move);
     to_insert.push_back(move);
     if (eliminate != nullptr) to_eliminate.push_back(eliminate);
   }
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8