[wasm] Add guard regions to end of WebAssembly.Memory buffers

src/objects-inl.h

 // 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.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 6952 matching lines @@
 
 uint32_t JSArrayBuffer::bit_field() const {
   return READ_UINT32_FIELD(this, kBitFieldOffset);
 }
 
 
 bool JSArrayBuffer::is_external() { return IsExternal::decode(bit_field()); }
 
 
 void JSArrayBuffer::set_is_external(bool value) {
+  DCHECK(!value || !has_guard_region());
   set_bit_field(IsExternal::update(bit_field(), value));
 }
 
 
 bool JSArrayBuffer::is_neuterable() {
   return IsNeuterable::decode(bit_field());
 }
 
 
 void JSArrayBuffer::set_is_neuterable(bool value) {
   set_bit_field(IsNeuterable::update(bit_field(), value));
 }
 
 
 bool JSArrayBuffer::was_neutered() { return WasNeutered::decode(bit_field()); }
 
 
 void JSArrayBuffer::set_was_neutered(bool value) {
   set_bit_field(WasNeutered::update(bit_field(), value));
 }
 
 
 bool JSArrayBuffer::is_shared() { return IsShared::decode(bit_field()); }
 
 
 void JSArrayBuffer::set_is_shared(bool value) {
   set_bit_field(IsShared::update(bit_field(), value));
 }
 
+bool JSArrayBuffer::has_guard_region() {
+  return HasGuardRegion::decode(bit_field());
+}
+
+void JSArrayBuffer::set_has_guard_region(bool value) {
+  set_bit_field(HasGuardRegion::update(bit_field(), value));
+}
 
 Object* JSArrayBufferView::byte_offset() const {
   if (WasNeutered()) return Smi::kZero;
   return Object::cast(READ_FIELD(this, kByteOffsetOffset));
 }
 
 
 void JSArrayBufferView::set_byte_offset(Object* value, WriteBarrierMode mode) {
   WRITE_FIELD(this, kByteOffsetOffset, value);
   CONDITIONAL_WRITE_BARRIER(GetHeap(), this, kByteOffsetOffset, value, mode);
@@ skipping 1419 matching lines @@
 #undef WRITE_INT64_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_INL_H_