MIPS64: Add optimizations to li and Dsubu macro.

src/mips64/macro-assembler-mips64.h

Index: src/mips64/macro-assembler-mips64.h
diff --git a/src/mips64/macro-assembler-mips64.h b/src/mips64/macro-assembler-mips64.h
index 695e1975d1136f0a77eff38edf16e567715e310a..c72f30c7f10c705f2ea2a575da6d9e03b134cbfb 100644
--- a/src/mips64/macro-assembler-mips64.h
+++ b/src/mips64/macro-assembler-mips64.h
@@ -740,6 +740,8 @@ class MacroAssembler: public Assembler {
 
   // Load int32 in the rd register.
   void li(Register rd, Operand j, LiFlags mode = OPTIMIZE_SIZE);
+  void li_optimized(Register rd, Operand j, LiFlags mode = OPTIMIZE_SIZE);
+  static int InstrCountForLi64Bit(int64_t value);
   inline void LiLower32BitHelper(Register rd, Operand j);
   inline void li(Register rd, int64_t j, LiFlags mode = OPTIMIZE_SIZE) {
     li(rd, Operand(j), mode);