ES6 symbols: Implement Symbol intrinsic and basic functionality

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 c554248cf4b45e9636178eae9e60c5ed265721d7..8a216ffc70b1e3b68965297d45fcb48872784c94 100644
--- a/src/ia32/full-codegen-ia32.cc
+++ b/src/ia32/full-codegen-ia32.cc
@@ -2549,6 +2549,7 @@ void FullCodeGenerator::EmitIsObject(CallRuntime* expr) {
 
 
 void FullCodeGenerator::EmitIsSpecObject(CallRuntime* expr) {
+  // TODO(rossberg): incorporate symbols.
   ZoneList<Expression*>* args = expr->arguments();
   ASSERT(args->length() == 1);
 
@@ -2684,6 +2685,28 @@ 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(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);
@@ -4263,6 +4286,10 @@ 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);