[Turbofan] Add support for 16 byte frame slots.

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 677 matching lines @@
     assigned_slot_ = index;
   }
   int assigned_slot() {
     DCHECK_NE(kUnassignedSlot, assigned_slot_);
     return assigned_slot_;
   }
   const ZoneVector<TopLevelLiveRange*>& live_ranges() const {
     return live_ranges_;
   }
   ZoneVector<TopLevelLiveRange*>& live_ranges() { return live_ranges_; }
-  // Currently, only 4 or 8 byte slots are supported in stack frames.
-  // TODO(bbudge) Add 16 byte slots for SIMD.
+  // Spill slots can be 4, 8, or 16 bytes wide.
   int byte_width() const { return byte_width_; }
   void Print() const;
 
  private:
   LifetimePosition End() const { return end_position_; }
   bool IsIntersectingWith(SpillRange* other) const;
   // Merge intervals, making sure the use intervals are sorted
   void MergeDisjointIntervals(UseInterval* other);
 
   ZoneVector<TopLevelLiveRange*> live_ranges_;
@@ skipping 473 matching lines @@
   RegisterAllocationData* const data_;
 
   DISALLOW_COPY_AND_ASSIGN(LiveRangeConnector);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_REGISTER_ALLOCATOR_H_