[turbofan] Spill rsi and rdi in their existing locations.

src/compiler/register-allocator.h

 // 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.
 
 #ifndef V8_REGISTER_ALLOCATOR_H_
 #define V8_REGISTER_ALLOCATOR_H_
 
 #include "src/compiler/instruction.h"
 #include "src/ostreams.h"
 #include "src/register-configuration.h"
@@ skipping 576 matching lines @@
   void SetSplinter(TopLevelLiveRange* splinter) {
     DCHECK_NULL(splinter_);
     DCHECK_NOT_NULL(splinter);
 
     splinter_ = splinter;
     splinter->relative_id_ = GetNextChildId();
     splinter->set_spill_type(spill_type());
     splinter->SetSplinteredFrom(this);
   }
 
+  void MarkElidableDef(MoveOperands* move) {

[Jarin, 2015/11/12 12:08:33]

elidable -> elidible (here and elsewhere)

+    DCHECK_NULL(elidable_def_);
+    elidable_def_ = move;
+  }
+
+  MoveOperands* elidable_def() const { return elidable_def_; }
+  bool IsReferenceAccountedByCaller() const { return elidable_def_ != nullptr; }
+
  private:
   void SetSplinteredFrom(TopLevelLiveRange* splinter_parent);
 
   typedef BitField<bool, 1, 1> HasSlotUseField;
   typedef BitField<bool, 2, 1> IsPhiField;
   typedef BitField<bool, 3, 1> IsNonLoopPhiField;
   typedef BitField<SpillType, 4, 2> SpillTypeField;
 
   int vreg_;
   int last_child_id_;
   TopLevelLiveRange* splintered_from_;
   union {
     // Correct value determined by spill_type()
     InstructionOperand* spill_operand_;
     SpillRange* spill_range_;
   };
   SpillAtDefinitionList* spills_at_definition_;
   // TODO(mtrofin): generalize spilling after definition, currently specialized
   // just for spill in a single deferred block.
   bool spilled_in_deferred_blocks_;
   int spill_start_index_;
   LiveRange* last_child_;
   UsePosition* last_pos_;
   TopLevelLiveRange* splinter_;
+  MoveOperands* elidable_def_;
 
   DISALLOW_COPY_AND_ASSIGN(TopLevelLiveRange);
 };
 
 
 struct PrintableLiveRange {
   const RegisterConfiguration* register_configuration_;
   const LiveRange* range_;
 };
 
@@ skipping 486 matching lines @@
   RegisterAllocationData* const data_;
 
   DISALLOW_COPY_AND_ASSIGN(LiveRangeConnector);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_REGISTER_ALLOCATOR_H_