ES6 symbols: Implement Symbol intrinsic and basic functionality

src/arm/full-codegen-arm.cc

Index: src/arm/full-codegen-arm.cc
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index 8dd0552b247e40b63c3701ce42099df7701d00ea..bfd01ff8c5ea117608154e7b596f44fba3e8693c 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -2752,6 +2752,28 @@ void FullCodeGenerator::EmitIsStringWrapperSafeForDefaultValueOf(
 }
 
 
+void FullCodeGenerator::EmitIsSymbol(CallRuntime* expr) {
+  ZoneList<Expression*>* args = expr->arguments();
+  ASSERT(args->length() == 1);
+
+  VisitForAccumulatorValue(args->at(0));
+
+  Label materialize_true, materialize_false;
+  Label* if_true = NULL;
+  Label* if_false = NULL;
+  Label* fall_through = NULL;
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
+
+  __ JumpIfSmi(r0, if_false);
+  __ CompareObjectType(r0, r1, r2, SYMBOL_TYPE);
+  PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
+  Split(eq, if_true, if_false, fall_through);
+
+  context()->Plug(if_true, if_false);
+}
+
+
 void FullCodeGenerator::EmitIsFunction(CallRuntime* expr) {
   ZoneList<Expression*>* args = expr->arguments();
   ASSERT(args->length() == 1);
@@ -4288,6 +4310,10 @@ void FullCodeGenerator::EmitLiteralCompareTypeof(Expression* expr,
       __ CompareRoot(r0, Heap::kNullValueRootIndex);
       __ b(eq, if_true);
     }
+    if (FLAG_harmony_symbols) {
+      __ CompareObjectType(r0, r0, r1, SYMBOL_TYPE);
+      __ b(eq, if_true);
+    }
     // Check for JS objects => true.
     __ CompareObjectType(r0, r0, r1, FIRST_NONCALLABLE_SPEC_OBJECT_TYPE);
     __ b(lt, if_false);