MIPS: Add big-endian support for MIPS.

src/objects.h

 // Copyright 2012 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 1935 matching lines @@
   void HeapNumberPrint(FILE* out = stdout);
   void HeapNumberPrint(StringStream* accumulator);
   DECLARE_VERIFIER(HeapNumber)
 
   inline int get_exponent();
   inline int get_sign();
 
   // Layout description.
   static const int kValueOffset = HeapObject::kHeaderSize;
   // IEEE doubles are two 32 bit words.  The first is just mantissa, the second
-  // is a mixture of sign, exponent and mantissa.  Our current platforms are all
-  // little endian apart from non-EABI arm which is little endian with big
-  // endian floating point word ordering!
+  // is a mixture of sign, exponent and mantissa. The offsets of two 32 bit
+  // words within double numbers are endian dependent and they are set
+  // accordingly.
+#if defined(V8_TARGET_LITTLE_ENDIAN)
   static const int kMantissaOffset = kValueOffset;
   static const int kExponentOffset = kValueOffset + 4;
+#elif defined(V8_TARGET_BIG_ENDIAN)
+  static const int kMantissaOffset = kValueOffset + 4;
+  static const int kExponentOffset = kValueOffset;
+#else
+#error Unknown byte ordering
+#endif
 
   static const int kSize = kValueOffset + kDoubleSize;
   static const uint32_t kSignMask = 0x80000000u;
   static const uint32_t kExponentMask = 0x7ff00000u;
   static const uint32_t kMantissaMask = 0xfffffu;
   static const int kMantissaBits = 52;
   static const int kExponentBits = 11;
   static const int kExponentBias = 1023;
   static const int kExponentShift = 20;
   static const int kInfinityOrNanExponent =
@@ skipping 5401 matching lines @@
       kOptCountAndBailoutReasonOffset + kIntSize;
 
   // Total size.
   static const int kSize = kCountersOffset + kIntSize;
 
 #endif
 
   // The construction counter for inobject slack tracking is stored in the
   // most significant byte of compiler_hints which is otherwise unused.
   // Its offset depends on the endian-ness of the architecture.
-#if __BYTE_ORDER == __LITTLE_ENDIAN
+#if defined(V8_TARGET_LITTLE_ENDIAN)
   static const int kConstructionCountOffset = kCompilerHintsOffset + 3;
-#elif __BYTE_ORDER == __BIG_ENDIAN
+#elif defined(V8_TARGET_BIG_ENDIAN)
   static const int kConstructionCountOffset = kCompilerHintsOffset + 0;
 #else
 #error Unknown byte ordering
 #endif
 
   static const int kAlignedSize = POINTER_SIZE_ALIGN(kSize);
 
   typedef FixedBodyDescriptor<kNameOffset,
                               kInitialMapOffset + kPointerSize,
                               kSize> BodyDescriptor;
@@ skipping 53 matching lines @@
  public:
   // Constants for optimizing codegen for strict mode function and
   // native tests.
   // Allows to use byte-width instructions.
   static const int kStrictModeBitWithinByte =
       (kStrictModeFunction + kCompilerHintsSmiTagSize) % kBitsPerByte;
 
   static const int kNativeBitWithinByte =
       (kNative + kCompilerHintsSmiTagSize) % kBitsPerByte;
 
-#if __BYTE_ORDER == __LITTLE_ENDIAN
+#if defined(V8_TARGET_LITTLE_ENDIAN)
   static const int kStrictModeByteOffset = kCompilerHintsOffset +
       (kStrictModeFunction + kCompilerHintsSmiTagSize) / kBitsPerByte;
   static const int kNativeByteOffset = kCompilerHintsOffset +
       (kNative + kCompilerHintsSmiTagSize) / kBitsPerByte;
-#elif __BYTE_ORDER == __BIG_ENDIAN
+#elif defined(V8_TARGET_BIG_ENDIAN)
   static const int kStrictModeByteOffset = kCompilerHintsOffset +
       (kCompilerHintsSize - 1) -
       ((kStrictModeFunction + kCompilerHintsSmiTagSize) / kBitsPerByte);
   static const int kNativeByteOffset = kCompilerHintsOffset +
       (kCompilerHintsSize - 1) -
       ((kNative + kCompilerHintsSmiTagSize) / kBitsPerByte);
 #else
 #error Unknown byte ordering
 #endif
 
@@ skipping 3548 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_