Cross-script variables handling fixed. It was possible to write to read-only global variable.

src/x64/code-stubs-x64.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.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
@@ skipping 5073 matching lines @@
 
   // Go up context chain to the script context.
   for (int i = 0; i < depth(); ++i) {
     __ movp(rdi, ContextOperand(context_reg, Context::PREVIOUS_INDEX));
     context_reg = rdi;
   }
 
   // Load the PropertyCell at the specified slot.
   __ movp(cell_reg, ContextOperand(context_reg, slot_reg));
 
+  // Check that value is not the_hole.
+  __ movp(cell_value_reg, FieldOperand(cell_reg, PropertyCell::kValueOffset));
+  __ CompareRoot(cell_value_reg, Heap::kTheHoleValueRootIndex);
+  __ j(equal, &slow_case, FLAG_debug_code ? Label::kFar : Label::kNear);
+
   // Load PropertyDetails for the cell (actually only the cell_type and kind).
   __ SmiToInteger32(cell_details_reg,
                     FieldOperand(cell_reg, PropertyCell::kDetailsOffset));
   __ andl(cell_details_reg,
           Immediate(PropertyDetails::PropertyCellTypeField::kMask |
                     PropertyDetails::KindField::kMask));
 
 
   // Check if PropertyCell holds mutable data.
   Label not_mutable_data;
   __ cmpl(cell_details_reg,
           Immediate(PropertyDetails::PropertyCellTypeField::encode(
                         PropertyCellType::kMutable) |
                     PropertyDetails::KindField::encode(kData)));
   __ j(not_equal, &not_mutable_data);
   __ JumpIfSmi(value_reg, &fast_smi_case);
   __ bind(&fast_heapobject_case);
   __ movp(FieldOperand(cell_reg, PropertyCell::kValueOffset), value_reg);
   __ RecordWriteField(cell_reg, PropertyCell::kValueOffset, value_reg,
                       cell_value_reg, kDontSaveFPRegs, EMIT_REMEMBERED_SET,
                       OMIT_SMI_CHECK);
   // RecordWriteField clobbers the value register, so we need to reload.
   __ movp(value_reg, FieldOperand(cell_reg, PropertyCell::kValueOffset));
   __ Ret();
   __ bind(&not_mutable_data);
 
   // Check if PropertyCell value matches the new value (relevant for Constant,
   // ConstantType and Undefined cells).
   Label not_same_value;
-  __ movp(cell_value_reg, FieldOperand(cell_reg, PropertyCell::kValueOffset));
   __ cmpp(cell_value_reg, value_reg);
   __ j(not_equal, &not_same_value,
        FLAG_debug_code ? Label::kFar : Label::kNear);
   if (FLAG_debug_code) {
     Label done;
     // This can only be true for Constant, ConstantType and Undefined cells,
     // because we never store the_hole via this stub.
     __ cmpl(cell_details_reg,
             Immediate(PropertyDetails::PropertyCellTypeField::encode(
                           PropertyCellType::kConstant) |
@@ skipping 448 matching lines @@
                            kStackSpace, nullptr, return_value_operand, NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64