Reland "[es6] Better support for built-ins subclassing."

src/arm64/builtins-arm64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "src/arm64/frames-arm64.h"
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
@@ skipping 191 matching lines @@
     __ TailCallRuntime(Runtime::kSymbolDescriptiveString, 1, 1);
   }
 }
 
 
 // static
 void Builtins::Generate_StringConstructor_ConstructStub(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- x0                     : number of arguments
   //  -- x1                     : constructor function
+  //  -- x3                     : original constructor
   //  -- lr                     : return address
   //  -- sp[(argc - n - 1) * 8] : arg[n] (zero based)
   //  -- sp[argc * 8]           : receiver
   // -----------------------------------
   ASM_LOCATION("Builtins::Generate_StringConstructor_ConstructStub");
 
   // 1. Load the first argument into x2 and get rid of the rest (including the
   // receiver).
   {
     Label no_arguments, done;
     __ Cbz(x0, &no_arguments);
     __ Sub(x0, x0, 1);
     __ Drop(x0);
     __ Ldr(x2, MemOperand(jssp, 2 * kPointerSize, PostIndex));
     __ B(&done);
     __ Bind(&no_arguments);
     __ Drop(1);
     __ LoadRoot(x2, Heap::kempty_stringRootIndex);
     __ Bind(&done);
   }
 
   // 2. Make sure x2 is a string.
   {
     Label convert, done_convert;
     __ JumpIfSmi(x2, &convert);
-    __ JumpIfObjectType(x2, x3, x3, FIRST_NONSTRING_TYPE, &done_convert, lo);
+    __ JumpIfObjectType(x2, x4, x4, FIRST_NONSTRING_TYPE, &done_convert, lo);
     __ Bind(&convert);
     {
       FrameScope scope(masm, StackFrame::INTERNAL);
       ToStringStub stub(masm->isolate());
-      __ Push(x1);
+      __ Push(x1, x3);
       __ Move(x0, x2);
       __ CallStub(&stub);
       __ Move(x2, x0);
-      __ Pop(x1);
+      __ Pop(x1, x3);
     }
     __ Bind(&done_convert);
   }
 
   // 3. Allocate a JSValue wrapper for the string.
   {
     // ----------- S t a t e -------------
+    //  -- x2 : the first argument
     //  -- x1 : constructor function
-    //  -- x2 : the first argument
+    //  -- x3 : original constructor
     //  -- lr : return address
     // -----------------------------------
 
-    Label allocate, done_allocate;
+    Label allocate, done_allocate, rt_call;
+
+    // Fall back to runtime if the original constructor and function differ.
+    __ cmp(x1, x3);
+    __ B(ne, &rt_call);
+
     __ Allocate(JSValue::kSize, x0, x3, x4, &allocate, TAG_OBJECT);
     __ Bind(&done_allocate);
 
     // Initialize the JSValue in eax.
     __ LoadGlobalFunctionInitialMap(x1, x3, x4);
     __ Str(x3, FieldMemOperand(x0, HeapObject::kMapOffset));
     __ LoadRoot(x3, Heap::kEmptyFixedArrayRootIndex);
     __ Str(x3, FieldMemOperand(x0, JSObject::kPropertiesOffset));
     __ Str(x3, FieldMemOperand(x0, JSObject::kElementsOffset));
     __ Str(x2, FieldMemOperand(x0, JSValue::kValueOffset));
     STATIC_ASSERT(JSValue::kSize == 4 * kPointerSize);
     __ Ret();
 
     // Fallback to the runtime to allocate in new space.
     __ Bind(&allocate);
     {
       FrameScope scope(masm, StackFrame::INTERNAL);
       __ Push(x1, x2);
       __ Push(Smi::FromInt(JSValue::kSize));
       __ CallRuntime(Runtime::kAllocateInNewSpace, 1);
       __ Pop(x2, x1);
     }
     __ B(&done_allocate);
+
+    // Fallback to the runtime to create new object.
+    __ bind(&rt_call);
+    {
+      FrameScope scope(masm, StackFrame::INTERNAL);
+      __ Push(x1, x2, x1, x3);  // constructor function, original constructor
+      __ CallRuntime(Runtime::kNewObject, 2);
+      __ Pop(x2, x1);
+    }
+    __ Str(x2, FieldMemOperand(x0, JSValue::kValueOffset));
+    __ Ret();
   }
 }
 
 
 static void CallRuntimePassFunction(MacroAssembler* masm,
                                     Runtime::FunctionId function_id) {
   FrameScope scope(masm, StackFrame::INTERNAL);
   //   - Push a copy of the function onto the stack.
   //   - Push another copy as a parameter to the runtime call.
   __ Push(x1, x1);
@@ skipping 36 matching lines @@
   GenerateTailCallToSharedCode(masm);
 }
 
 
 static void Generate_JSConstructStubHelper(MacroAssembler* masm,
                                            bool is_api_function) {
   // ----------- S t a t e -------------
   //  -- x0     : number of arguments
   //  -- x1     : constructor function
   //  -- x2     : allocation site or undefined
-  //  -- x3    : original constructor
+  //  -- x3     : original constructor
   //  -- lr     : return address
   //  -- sp[...]: constructor arguments
   // -----------------------------------
 
   ASM_LOCATION("Builtins::Generate_JSConstructStubHelper");
 
   Isolate* isolate = masm->isolate();
 
   // Enter a construct frame.
   {
@@ skipping 1639 matching lines @@
   }
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM