Implement byte swapping instructions on MIPS32 and MIPS64.

src/mips/macro-assembler-mips.h

Index: src/mips/macro-assembler-mips.h
diff --git a/src/mips/macro-assembler-mips.h b/src/mips/macro-assembler-mips.h
index 24170252daed50006d2caaeb58173b7177f31d20..5bcfe1ce92844df297afbaa4378c9849c678e5cc 100644
--- a/src/mips/macro-assembler-mips.h
+++ b/src/mips/macro-assembler-mips.h
@@ -687,6 +687,10 @@ class MacroAssembler: public Assembler {
   // ---------------------------------------------------------------------------
   // Pseudo-instructions.
 
+  // Change endianness
+  void ByteSwapSigned(Register reg, int operand_size);
+  void ByteSwapUnsigned(Register reg, int operand_size);
+
   void mov(Register rd, Register rt) { or_(rd, rt, zero_reg); }
 
   void Ulh(Register rd, const MemOperand& rs);