MIPS64: Implement AddE lithium instruction to separate integer and address arithmetic.

src/mips64/lithium-mips64.h

Index: src/mips64/lithium-mips64.h
diff --git a/src/mips64/lithium-mips64.h b/src/mips64/lithium-mips64.h
index fa1c2d2b4347ef3927d104862294a9ba5b15480c..6928ae4b06a5549e041352cbd6c199086b6adc07 100644
--- a/src/mips64/lithium-mips64.h
+++ b/src/mips64/lithium-mips64.h
@@ -20,6 +20,7 @@ class LCodeGen;
 #define LITHIUM_CONCRETE_INSTRUCTION_LIST(V) \
   V(AccessArgumentsAt)                       \
   V(AddI)                                    \
+  V(AddE)                                    \
   V(Allocate)                                \
   V(AllocateBlockContext)                    \
   V(ApplyArguments)                          \
@@ -1421,6 +1422,21 @@ class LSeqStringSetChar final : public LTemplateInstruction<1, 4, 0> {
 };
 
 
+class LAddE final : public LTemplateInstruction<1, 2, 0> {
+ public:
+  LAddE(LOperand* left, LOperand* right) {
+    inputs_[0] = left;
+    inputs_[1] = right;
+  }
+
+  LOperand* left() { return inputs_[0]; }
+  LOperand* right() { return inputs_[1]; }
+
+  DECLARE_CONCRETE_INSTRUCTION(AddE, "add-e")
+  DECLARE_HYDROGEN_ACCESSOR(Add)
+};
+
+
 class LAddI final : public LTemplateInstruction<1, 2, 0> {
  public:
   LAddI(LOperand* left, LOperand* right) {