Introduce DisallowDeoptimization scope.

R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/254763007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20998 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/assert-scope.h

@@ -50,7 +50,8 @@ enum PerThreadAssertType {
 enum PerIsolateAssertType {
   JAVASCRIPT_EXECUTION_ASSERT,
   JAVASCRIPT_EXECUTION_THROWS,
-  ALLOCATION_FAILURE_ASSERT
+  ALLOCATION_FAILURE_ASSERT,
+  DEOPTIMIZATION_ASSERT
 };
 
 
@@ -268,6 +269,14 @@ typedef PerIsolateAssertScopeDebugOnly<ALLOCATION_FAILURE_ASSERT, false>
 typedef PerIsolateAssertScopeDebugOnly<ALLOCATION_FAILURE_ASSERT, true>
     AllowAllocationFailure;
 
+// Scope to document where we do not expect deoptimization.
+typedef PerIsolateAssertScopeDebugOnly<DEOPTIMIZATION_ASSERT, false>
+    DisallowDeoptimization;
+
+// Scope to introduce an exception to DisallowDeoptimization.
+typedef PerIsolateAssertScopeDebugOnly<DEOPTIMIZATION_ASSERT, true>
+    AllowDeoptimization;
+
 } }  // namespace v8::internal
 
 #endif  // V8_ASSERT_SCOPE_H_

src/objects-inl.h

@@ -4679,6 +4679,7 @@ bool Code::marked_for_deoptimization() {
 
 void Code::set_marked_for_deoptimization(bool flag) {
   ASSERT(kind() == OPTIMIZED_FUNCTION);
+  ASSERT(!flag || AllowDeoptimization::IsAllowed(GetIsolate()));
   int previous = READ_UINT32_FIELD(this, kKindSpecificFlags1Offset);
   int updated = MarkedForDeoptimizationField::update(previous, flag);
   WRITE_UINT32_FIELD(this, kKindSpecificFlags1Offset, updated);

src/objects.cc

@@ -2781,6 +2781,7 @@ MaybeHandle<Map> Map::CurrentMapForDeprecated(Handle<Map> map) {
 // static
 MaybeHandle<Map> Map::CurrentMapForDeprecatedInternal(Handle<Map> old_map) {
   DisallowHeapAllocation no_allocation;
+  DisallowDeoptimization no_deoptimization(old_map->GetIsolate());
 
   if (!old_map->is_deprecated()) return old_map;
 
@@ -3940,7 +3941,9 @@ void JSObject::MigrateInstance(Handle<JSObject> object) {
 
 // static
 bool JSObject::TryMigrateInstance(Handle<JSObject> object) {
-  Handle<Map> original_map(object->map());
+  Isolate* isolate = object->GetIsolate();
+  DisallowDeoptimization no_deoptimization(isolate);
+  Handle<Map> original_map(object->map(), isolate);
   Handle<Map> new_map;
   if (!Map::CurrentMapForDeprecatedInternal(original_map).ToHandle(&new_map)) {
     return false;