A64: Implement LPower and extend MathPowStub to support args in registers

src/a64/lithium-a64.h

Index: src/a64/lithium-a64.h
diff --git a/src/a64/lithium-a64.h b/src/a64/lithium-a64.h
index 7af082011b3f8f662ce6df3f39684285315adb35..fb122f2958a871c317d947e1e96dbecae814fc33 100644
--- a/src/a64/lithium-a64.h
+++ b/src/a64/lithium-a64.h
@@ -154,6 +154,7 @@ class LCodeGen;
   V(OsrEntry)                                   \
   V(OuterContext)                               \
   V(Parameter)                                  \
+  V(Power)                                      \
   V(PushArgument)                               \
   V(RegExpLiteral)                              \
   V(Return)                                     \
@@ -1984,6 +1985,21 @@ class LParameter: public LTemplateInstruction<1, 0, 0> {
 };
 
 
+class LPower: public LTemplateInstruction<1, 2, 0> {
+ public:
+  LPower(LOperand* left, LOperand* right) {
+    inputs_[0] = left;
+    inputs_[1] = right;
+  }
+
+  LOperand* left() { return inputs_[0]; }
+  LOperand* right() { return inputs_[1]; }
+
+  DECLARE_CONCRETE_INSTRUCTION(Power, "power")
+  DECLARE_HYDROGEN_ACCESSOR(Power)
+};
+
+
 class LPushArgument: public LTemplateInstruction<0, 1, 0> {
  public:
   explicit LPushArgument(LOperand* value) {