MIPS: ES6 symbols: turn symbols into a proper primitive type

Port r14051 (e9140a92)

Original commit message:
(qua last week's TC39)

Specifically:
- Install Symbol constructor function on the global object.
- Adjust code generation for typeof.
- Remove IsSymbol built-in, IS_SYMBOL macro now defined using typeof.
- Remove hack that allowed symbols as constructor results, and some other special cases.
- Remove symbol_delegate and GetDelegate function.
- Extend ToBoolean stub to handle symbols.
- Extend ToNumber to return NaN on symbols.
- Poison symbol's toString function, and thereby ToString on symbols.

BUG=

Review URL: https://codereview.chromium.org/13007003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14058 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/builtins-mips.cc

@@ -1130,10 +1130,6 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
     __ GetObjectType(v0, a1, a3);
     __ Branch(&exit, greater_equal, a3, Operand(FIRST_SPEC_OBJECT_TYPE));
 
-    // Symbols are "objects".
-    __ lbu(a3, FieldMemOperand(a1, Map::kInstanceTypeOffset));
-    __ Branch(&exit, eq, a3, Operand(SYMBOL_TYPE));
-
     // Throw away the result of the constructor invocation and use the
     // on-stack receiver as the result.
     __ bind(&use_receiver);

src/mips/full-codegen-mips.cc

@@ -2780,28 +2780,6 @@ 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(v0, if_false);
-  __ GetObjectType(v0, a1, a2);
-  PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
-  Split(eq, a2, Operand(SYMBOL_TYPE), 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);
@@ -4320,6 +4298,10 @@ void FullCodeGenerator::EmitLiteralCompareTypeof(Expression* expr,
     __ And(a1, a1, Operand(1 << Map::kIsUndetectable));
     Split(eq, a1, Operand(zero_reg),
           if_true, if_false, fall_through);
+  } else if (check->Equals(isolate()->heap()->symbol_string())) {
+    __ JumpIfSmi(v0, if_false);
+    __ GetObjectType(v0, v0, a1);
+    Split(eq, a1, Operand(SYMBOL_TYPE), if_true, if_false, fall_through);
   } else if (check->Equals(isolate()->heap()->boolean_string())) {
     __ LoadRoot(at, Heap::kTrueValueRootIndex);
     __ Branch(if_true, eq, v0, Operand(at));
@@ -4351,10 +4333,6 @@ void FullCodeGenerator::EmitLiteralCompareTypeof(Expression* expr,
       __ LoadRoot(at, Heap::kNullValueRootIndex);
       __ Branch(if_true, eq, v0, Operand(at));
     }
-    if (FLAG_harmony_symbols) {
-      __ GetObjectType(v0, v0, a1);
-      __ Branch(if_true, eq, a1, Operand(SYMBOL_TYPE));
-    }
     // Check for JS objects => true.
     __ GetObjectType(v0, v0, a1);
     __ Branch(if_false, lt, a1, Operand(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));

src/mips/lithium-codegen-mips.cc

@@ -1901,6 +1901,13 @@ void LCodeGen::DoBranch(LBranch* instr) {
         __ bind(&not_string);
       }
 
+      if (expected.Contains(ToBooleanStub::SYMBOL)) {
+        // Symbol value -> true.
+        const Register scratch = scratch1();
+        __ lbu(scratch, FieldMemOperand(map, Map::kInstanceTypeOffset));
+        __ Branch(true_label, eq, scratch, Operand(SYMBOL_TYPE));
+      }
+
       if (expected.Contains(ToBooleanStub::HEAP_NUMBER)) {
         CpuFeatureScope scope(masm(), FPU);
         // heap number -> false iff +0, -0, or NaN.
@@ -5771,6 +5778,13 @@ Condition LCodeGen::EmitTypeofIs(Label* true_label,
     cmp2 = Operand(zero_reg);
     final_branch_condition = eq;
 
+  } else if (type_name->Equals(heap()->symbol_string())) {
+    __ JumpIfSmi(input, false_label);
+    __ GetObjectType(input, input, scratch);
+    cmp1 = scratch;
+    cmp2 = Operand(SYMBOL_TYPE);
+    final_branch_condition = eq;
+
   } else if (type_name->Equals(heap()->boolean_string())) {
     __ LoadRoot(at, Heap::kTrueValueRootIndex);
     __ Branch(USE_DELAY_SLOT, true_label, eq, at, Operand(input));
@@ -5814,20 +5828,10 @@ Condition LCodeGen::EmitTypeofIs(Label* true_label,
       __ LoadRoot(at, Heap::kNullValueRootIndex);
       __ Branch(USE_DELAY_SLOT, true_label, eq, at, Operand(input));
     }
-    if (FLAG_harmony_symbols) {
-      // input is an object, it is safe to use GetObjectType in the delay slot.
-      __ GetObjectType(input, input, scratch);
-      __ Branch(USE_DELAY_SLOT, true_label, eq, scratch, Operand(SYMBOL_TYPE));
-      // Still an object, so the InstanceType can be loaded.
-      __ lbu(scratch, FieldMemOperand(input, Map::kInstanceTypeOffset));
-      __ Branch(USE_DELAY_SLOT, false_label,
-                lt, scratch, Operand(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
-    } else {
-      // input is an object, it is safe to use GetObjectType in the delay slot.
-      __ GetObjectType(input, input, scratch);
-      __ Branch(USE_DELAY_SLOT, false_label,
-                lt, scratch, Operand(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
-    }
+    // input is an object, it is safe to use GetObjectType in the delay slot.
+    __ GetObjectType(input, input, scratch);
+    __ Branch(USE_DELAY_SLOT, false_label,
+              lt, scratch, Operand(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
     // Still an object, so the InstanceType can be loaded.
     __ lbu(scratch, FieldMemOperand(input, Map::kInstanceTypeOffset));
     __ Branch(USE_DELAY_SLOT, false_label,

src/mips/stub-cache-mips.cc

@@ -2424,6 +2424,12 @@ void CallStubCompiler::CompileHandlerFrontend(Handle<Object> object,
       // Check that the object is a symbol.
       __ GetObjectType(a1, a1, a3);
       __ Branch(&miss, ne, a3, Operand(SYMBOL_TYPE));
+      // Check that the maps starting from the prototype haven't changed.
+      GenerateDirectLoadGlobalFunctionPrototype(
+          masm(), Context::SYMBOL_FUNCTION_INDEX, a0, &miss);
+      CheckPrototypes(
+          Handle<JSObject>(JSObject::cast(object->GetPrototype(isolate()))),
+          a0, holder, a3, a1, t0, name, &miss);
       break;
 
     case NUMBER_CHECK: {