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

src/mips/builtins-mips.cc

 // Copyright 2012 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_MIPS
 
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 209 matching lines @@
     __ TailCallRuntime(Runtime::kSymbolDescriptiveString, 1, 1);
   }
 }
 
 
 // static
 void Builtins::Generate_StringConstructor_ConstructStub(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- a0                     : number of arguments
   //  -- a1                     : constructor function
+  //  -- a3                     : original constructor
   //  -- ra                     : return address
   //  -- sp[(argc - n - 1) * 4] : arg[n] (zero based)
   //  -- sp[argc * 4]           : receiver
   // -----------------------------------
 
   // 1. Load the first argument into a0 and get rid of the rest (including the
   // receiver).
   {
     Label no_arguments, done;
     __ Branch(USE_DELAY_SLOT, &no_arguments, eq, a0, Operand(zero_reg));
@@ skipping 13 matching lines @@
   {
     Label convert, done_convert;
     __ JumpIfSmi(a0, &convert);
     __ GetObjectType(a0, a2, a2);
     __ And(t0, a2, Operand(kIsNotStringMask));
     __ Branch(&done_convert, eq, t0, Operand(zero_reg));
     __ bind(&convert);
     {
       FrameScope scope(masm, StackFrame::INTERNAL);
       ToStringStub stub(masm->isolate());
-      __ Push(a1);
+      __ Push(a1, a3);
       __ CallStub(&stub);
       __ Move(a0, v0);
-      __ Pop(a1);
+      __ Pop(a1, a3);
     }
     __ bind(&done_convert);
   }
 
   // 3. Allocate a JSValue wrapper for the string.
   {
     // ----------- S t a t e -------------
     //  -- a0 : the first argument
     //  -- a1 : constructor function
+    //  -- a3 : original constructor
     //  -- ra : return address
     // -----------------------------------
 
-    Label allocate, done_allocate;
+    Label allocate, done_allocate, rt_call;
+
+    // Fall back to runtime if the original constructor and function differ.
+    __ Branch(&rt_call, ne, a1, Operand(a3));
+
     __ Allocate(JSValue::kSize, v0, a2, a3, &allocate, TAG_OBJECT);
     __ bind(&done_allocate);
 
     // Initialize the JSValue in eax.
     __ LoadGlobalFunctionInitialMap(a1, a2, a3);
     __ sw(a2, FieldMemOperand(v0, HeapObject::kMapOffset));
     __ LoadRoot(a3, Heap::kEmptyFixedArrayRootIndex);
     __ sw(a3, FieldMemOperand(v0, JSObject::kPropertiesOffset));
     __ sw(a3, FieldMemOperand(v0, JSObject::kElementsOffset));
     __ Ret(USE_DELAY_SLOT);
     __ sw(a0, FieldMemOperand(v0, JSValue::kValueOffset));
     STATIC_ASSERT(JSValue::kSize == 4 * kPointerSize);
 
     // Fallback to the runtime to allocate in new space.
     __ bind(&allocate);
     {
       FrameScope scope(masm, StackFrame::INTERNAL);
       __ Move(a2, Smi::FromInt(JSValue::kSize));
       __ Push(a0, a1, a2);
       __ CallRuntime(Runtime::kAllocateInNewSpace, 1);
       __ Pop(a0, a1);
     }
     __ jmp(&done_allocate);
+
+    // Fallback to the runtime to create new object.
+    __ bind(&rt_call);
+    {
+      FrameScope scope(masm, StackFrame::INTERNAL);
+      __ Push(a0, a1, a1, a3);  // constructor function, original constructor
+      __ CallRuntime(Runtime::kNewObject, 2);
+      __ Pop(a0, a1);
+    }
+    __ Ret(USE_DELAY_SLOT);
+    __ sw(a0, FieldMemOperand(v0, JSValue::kValueOffset));
   }
 }
 
 
 static void CallRuntimePassFunction(
     MacroAssembler* masm, Runtime::FunctionId function_id) {
   FrameScope scope(masm, StackFrame::INTERNAL);
   // Push a copy of the function onto the stack.
   // Push call kind information and function as parameter to the runtime call.
   __ Push(a1, a1);
@@ skipping 190 matching lines @@
       // Reload the original constructor and fall-through.
       __ bind(&rt_call_reload_new_target);
       __ lw(a3, MemOperand(sp, 0 * kPointerSize));
     }
 
     // Allocate the new receiver object using the runtime call.
     // a1: constructor function
     // a3: original constructor
     __ bind(&rt_call);
 
-    __ Push(a1, a3);  // arguments 2-3 / 1-2
+    __ Push(a1, a3);  // constructor function, original constructor
     __ CallRuntime(Runtime::kNewObject, 2);
     __ mov(t4, v0);
 
     // Receiver for constructor call allocated.
     // t4: JSObject
     __ bind(&allocated);
 
     // Restore the parameters.
     __ Pop(a3);  // new.target
     __ Pop(a1);
@@ skipping 1405 matching lines @@
   }
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS