Change return type of FrameDescription::GetFrameSize to avoid unneeded type casts.

src/deoptimizer.h

 // Copyright 2011 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 322 matching lines @@
   void* operator new(size_t size, uint32_t frame_size) {
     // Subtracts kPointerSize, as the member frame_content_ already supplies
     // the first element of the area to store the frame.
     return malloc(size + frame_size - kPointerSize);
   }
 
   void operator delete(void* description) {
     free(description);
   }
 
-  intptr_t GetFrameSize() const { return frame_size_; }
+  uint32_t GetFrameSize() const {
+    ASSERT(static_cast<uint32_t>(frame_size_) == frame_size_);
+    return static_cast<uint32_t>(frame_size_);
+  }
 
   JSFunction* GetFunction() const { return function_; }
 
   unsigned GetOffsetFromSlotIndex(Deoptimizer* deoptimizer, int slot_index);
 
   intptr_t GetFrameSlot(unsigned offset) {
     return *GetFrameSlotPointer(offset);
   }
 
   double GetDoubleFrameSlot(unsigned offset) {
@@ skipping 73 matching lines @@
     return OFFSET_OF(FrameDescription, continuation_);
   }
 
   static int frame_content_offset() {
     return OFFSET_OF(FrameDescription, frame_content_);
   }
 
  private:
   static const uint32_t kZapUint32 = 0xbeeddead;
 
+  // Frame_size_ must hold a uint32_t value.  It is only a uintptr_t to
+  // keep the variable-size array frame_content_ of type intptr_t at
+  // the end of the structure aligned.
   uintptr_t frame_size_;  // Number of bytes.
   JSFunction* function_;
   intptr_t registers_[Register::kNumRegisters];
   double double_registers_[DoubleRegister::kNumAllocatableRegisters];
   intptr_t top_;
   intptr_t pc_;
   intptr_t fp_;
   Smi* state_;
 #ifdef DEBUG
   Code::Kind kind_;
@@ skipping 228 matching lines @@
   int expression_count_;
   Object** expression_stack_;
 
   friend class Deoptimizer;
 };
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_DEOPTIMIZER_H_