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
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@@ 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 __BYTE_ORDER == __LITTLE_ENDIAN

[Jakob Kummerow, 2014/04/15 08:11:20]

Any reason this doesn't use V8_TARGET_LITTLE_ENDIAN?

[dusmil, 2014/04/15 15:22:22]

It is used to keep consistency because there are other ifdef uses of BYTE_ORDER
in this file. I change all of them to check V8_TARGET_LITTLE_ENDIAN and
V8_TARGET_BIG_ENDIAN now.

[dusmil, 2014/04/15 15:22:22]

Done.

   static const int kMantissaOffset = kValueOffset;
   static const int kExponentOffset = kValueOffset + 4;
+#elif __BYTE_ORDER == __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 9051 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_