ES6 symbols: turn symbols into a proper primitive type

src/ia32/full-codegen-ia32.cc

Index: src/ia32/full-codegen-ia32.cc
diff --git a/src/ia32/full-codegen-ia32.cc b/src/ia32/full-codegen-ia32.cc
index ebc3a2bd5cae7dc672170f66aa27c42ba98fa71c..efbdf135445b9988494af3affdfab5775f3bd9f4 100644
--- a/src/ia32/full-codegen-ia32.cc
+++ b/src/ia32/full-codegen-ia32.cc
@@ -2567,7 +2567,6 @@ void FullCodeGenerator::EmitIsObject(CallRuntime* expr) {
 
 
 void FullCodeGenerator::EmitIsSpecObject(CallRuntime* expr) {
-  // TODO(rossberg): incorporate symbols.
   ZoneList<Expression*>* args = expr->arguments();
   ASSERT(args->length() == 1);
 
@@ -2703,28 +2702,6 @@ 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(eax, if_false);
-  __ CmpObjectType(eax, SYMBOL_TYPE, ebx);
-  PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
-  Split(equal, 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);
@@ -4275,6 +4252,10 @@ void FullCodeGenerator::EmitLiteralCompareTypeof(Expression* expr,
     __ test_b(FieldOperand(edx, Map::kBitFieldOffset),
               1 << Map::kIsUndetectable);
     Split(zero, if_true, if_false, fall_through);
+  } else if (check->Equals(isolate()->heap()->symbol_string())) {
+    __ JumpIfSmi(eax, if_false);
+    __ CmpObjectType(eax, SYMBOL_TYPE, edx);
+    Split(equal, if_true, if_false, fall_through);
   } else if (check->Equals(isolate()->heap()->boolean_string())) {
     __ cmp(eax, isolate()->factory()->true_value());
     __ j(equal, if_true);
@@ -4306,10 +4287,6 @@ void FullCodeGenerator::EmitLiteralCompareTypeof(Expression* expr,
       __ cmp(eax, isolate()->factory()->null_value());
       __ j(equal, if_true);
     }
-    if (FLAG_harmony_symbols) {
-      __ CmpObjectType(eax, SYMBOL_TYPE, edx);
-      __ j(equal, if_true);
-    }
     __ CmpObjectType(eax, FIRST_NONCALLABLE_SPEC_OBJECT_TYPE, edx);
     __ j(below, if_false);
     __ CmpInstanceType(edx, LAST_NONCALLABLE_SPEC_OBJECT_TYPE);