[Turbofan] Add support for 16 byte frame slots.

src/compiler/frame.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_COMPILER_FRAME_H_
 #define V8_COMPILER_FRAME_H_
 
 #include "src/bit-vector.h"
 #include "src/frames.h"
 
@@ skipping 105 matching lines @@
     spill_slot_count_ += static_cast<int>(slot_count);
     frame_slot_count_ += static_cast<int>(slot_count);
     return frame_slot_count_ - 1;
   }
 
   static const int kContextSlot = 2 + StandardFrameConstants::kCPSlotCount;
   static const int kJSFunctionSlot = 3 + StandardFrameConstants::kCPSlotCount;
 
  private:
   int AllocateAlignedFrameSlot(int width) {
-    DCHECK(width == 4 || width == 8);
-    // Skip one slot if necessary.
-    if (width > kPointerSize) {
-      DCHECK(width == kPointerSize * 2);
-      frame_slot_count_++;
-      frame_slot_count_ |= 1;
+    DCHECK(width == 4 || width == 8 || width == 16);
+    if (kPointerSize == 4) {
+      // Skip one slot if necessary.
+      if (width > kPointerSize) {
+        frame_slot_count_++;
+        frame_slot_count_ |= 1;
+        // 2 extra slots if width == 16.
+        frame_slot_count_ += (width & 16) / 8;
+      }
+    } else {
+      // No alignment when slots are 8 bytes.
+      DCHECK_EQ(8, kPointerSize);
+      // 1 extra slot if width == 16.
+      frame_slot_count_ += (width & 16) / 16;
     }
     return frame_slot_count_++;
   }
 
  private:
   int frame_slot_count_;
   int spill_slot_count_;
   BitVector* allocated_registers_;
   BitVector* allocated_double_registers_;
 
@@ skipping 72 matching lines @@
   const Frame* const frame_;
   bool access_frame_with_fp_;
   int sp_delta_;
   bool has_frame_;
 };
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_FRAME_H_