Reland "Remove V8_HOST_CAN_READ_UNALIGNED and its uses."

src/deoptimizer.h

 // Copyright 2012 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_DEOPTIMIZER_H_
 #define V8_DEOPTIMIZER_H_
 
 #include "src/v8.h"
 
 #include "src/allocation.h"
 #include "src/macro-assembler.h"
 #include "src/zone-inl.h"
 
 
 namespace v8 {
 namespace internal {
 
 
 static inline double read_double_value(Address p) {
-#ifdef V8_HOST_CAN_READ_UNALIGNED
-  return Memory::double_at(p);
-#else  // V8_HOST_CAN_READ_UNALIGNED
   // Prevent gcc from using load-double (mips ldc1) on (possibly)
   // non-64-bit aligned address.
+  // We assume that the address is 32-bit aligned.
+  DCHECK(IsAligned(reinterpret_cast<intptr_t>(p), kInt32Size));
   union conversion {
     double d;
     uint32_t u[2];
   } c;
-  c.u[0] = *reinterpret_cast<uint32_t*>(p);
-  c.u[1] = *reinterpret_cast<uint32_t*>(p + 4);
+  c.u[0] = Memory::uint32_at(p);
+  c.u[1] = Memory::uint32_at(p + 4);
   return c.d;
-#endif  // V8_HOST_CAN_READ_UNALIGNED
 }
 
 
 class FrameDescription;
 class TranslationIterator;
 class DeoptimizedFrameInfo;
 
 template<typename T>
 class HeapNumberMaterializationDescriptor BASE_EMBEDDED {
  public:
@@ skipping 923 matching lines @@
   Object** parameters_;
   Object** expression_stack_;
   int source_position_;
 
   friend class Deoptimizer;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_DEOPTIMIZER_H_