ES6 symbols: turn symbols into a proper primitive type

src/arm/lithium-codegen-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2283 matching lines @@
         Label not_string;
         __ CompareInstanceType(map, ip, FIRST_NONSTRING_TYPE);
         __ b(ge, &not_string);
         __ ldr(ip, FieldMemOperand(reg, String::kLengthOffset));
         __ cmp(ip, Operand::Zero());
         __ b(ne, true_label);
         __ b(false_label);
         __ bind(&not_string);
       }
 
+      if (expected.Contains(ToBooleanStub::SYMBOL)) {
+        // Symbol value -> true.
+        __ CompareInstanceType(map, ip, SYMBOL_TYPE);
+        __ b(eq, true_label);
+      }
+
       if (expected.Contains(ToBooleanStub::HEAP_NUMBER)) {
         CpuFeatureScope scope(masm(), VFP2);
         // heap number -> false iff +0, -0, or NaN.
         DwVfpRegister dbl_scratch = double_scratch0();
         Label not_heap_number;
         __ CompareRoot(map, Heap::kHeapNumberMapRootIndex);
         __ b(ne, &not_heap_number);
         __ vldr(dbl_scratch, FieldMemOperand(reg, HeapNumber::kValueOffset));
         __ VFPCompareAndSetFlags(dbl_scratch, 0.0);
         __ b(vs, false_label);  // NaN -> false.
@@ skipping 3753 matching lines @@
     final_branch_condition = eq;
 
   } else if (type_name->Equals(heap()->string_string())) {
     __ JumpIfSmi(input, false_label);
     __ CompareObjectType(input, input, scratch, FIRST_NONSTRING_TYPE);
     __ b(ge, false_label);
     __ ldrb(ip, FieldMemOperand(input, Map::kBitFieldOffset));
     __ tst(ip, Operand(1 << Map::kIsUndetectable));
     final_branch_condition = eq;
 
+  } else if (type_name->Equals(heap()->symbol_string())) {
+    __ JumpIfSmi(input, false_label);
+    __ CompareObjectType(input, input, scratch, SYMBOL_TYPE);
+    final_branch_condition = eq;
+
   } else if (type_name->Equals(heap()->boolean_string())) {
     __ CompareRoot(input, Heap::kTrueValueRootIndex);
     __ b(eq, true_label);
     __ CompareRoot(input, Heap::kFalseValueRootIndex);
     final_branch_condition = eq;
 
   } else if (FLAG_harmony_typeof && type_name->Equals(heap()->null_string())) {
     __ CompareRoot(input, Heap::kNullValueRootIndex);
     final_branch_condition = eq;
 
@@ skipping 14 matching lines @@
     __ b(eq, true_label);
     __ cmp(input, Operand(JS_FUNCTION_PROXY_TYPE));
     final_branch_condition = eq;
 
   } else if (type_name->Equals(heap()->object_string())) {
     __ JumpIfSmi(input, false_label);
     if (!FLAG_harmony_typeof) {
       __ CompareRoot(input, Heap::kNullValueRootIndex);
       __ b(eq, true_label);
     }
-    if (FLAG_harmony_symbols) {
-      __ CompareObjectType(input, input, scratch, SYMBOL_TYPE);
-      __ b(eq, true_label);
-      __ CompareInstanceType(input, scratch,
-                             FIRST_NONCALLABLE_SPEC_OBJECT_TYPE);
-    } else {
-      __ CompareObjectType(input, input, scratch,
-                           FIRST_NONCALLABLE_SPEC_OBJECT_TYPE);
-    }
+    __ CompareObjectType(input, input, scratch,
+                         FIRST_NONCALLABLE_SPEC_OBJECT_TYPE);
     __ b(lt, false_label);
     __ CompareInstanceType(input, scratch, LAST_NONCALLABLE_SPEC_OBJECT_TYPE);
     __ b(gt, false_label);
     // Check for undetectable objects => false.
     __ ldrb(ip, FieldMemOperand(input, Map::kBitFieldOffset));
     __ tst(ip, Operand(1 << Map::kIsUndetectable));
     final_branch_condition = eq;
 
   } else {
     __ b(false_label);
@@ skipping 263 matching lines @@
   __ sub(scratch, result, Operand(index, LSL, kPointerSizeLog2 - kSmiTagSize));
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal