Make Isolate::AddDetachedContext GC safe

src/isolate.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.
 
 #include "src/isolate.h"
 
 #include <stdlib.h>
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
@@ skipping 3491 matching lines @@
 }
 
 
 void Isolate::RunMicrotasksInternal() {
   if (!pending_microtask_count()) return;
   TRACE_EVENT0("v8.execute", "RunMicrotasks");
   TRACE_EVENT_CALL_STATS_SCOPED(this, "v8", "V8.RunMicrotasks");
   while (pending_microtask_count() > 0) {
     HandleScope scope(this);
     int num_tasks = pending_microtask_count();
+    // Do not use factory()->microtask_queue() here; we need a fresh handle!
     Handle<FixedArray> queue(heap()->microtask_queue(), this);
     DCHECK(num_tasks <= queue->length());
     set_pending_microtask_count(0);
     heap()->set_microtask_queue(heap()->empty_fixed_array());
 
     Isolate* isolate = this;
     FOR_WITH_HANDLE_SCOPE(isolate, int, i = 0, i, i < num_tasks, i++, {
       Handle<Object> microtask(queue->get(i), this);
 
       if (microtask->IsCallHandlerInfo()) {
@@ skipping 123 matching lines @@
   // deoptimize only those functions that are affected by the change of this
   // flag.
   internal::Deoptimizer::DeoptimizeAll(this);
 }
 
 // Heap::detached_contexts tracks detached contexts as pairs
 // (number of GC since the context was detached, the context).
 void Isolate::AddDetachedContext(Handle<Context> context) {
   HandleScope scope(this);
   Handle<WeakCell> cell = factory()->NewWeakCell(context);
-  Handle<FixedArray> detached_contexts = factory()->detached_contexts();
-  int length = detached_contexts->length();
-  detached_contexts = factory()->CopyFixedArrayAndGrow(detached_contexts, 2);
-  detached_contexts->set(length, Smi::kZero);
-  detached_contexts->set(length + 1, *cell);
+  Handle<FixedArray> detached_contexts =
+      factory()->CopyFixedArrayAndGrow(factory()->detached_contexts(), 2);
+  int new_length = detached_contexts->length();
+  detached_contexts->set(new_length - 2, Smi::kZero);
+  detached_contexts->set(new_length - 1, *cell);
   heap()->set_detached_contexts(*detached_contexts);
 }
 
 
 void Isolate::CheckDetachedContextsAfterGC() {
   HandleScope scope(this);
   Handle<FixedArray> detached_contexts = factory()->detached_contexts();
   int length = detached_contexts->length();
   if (length == 0) return;
   int new_length = 0;
@@ skipping 105 matching lines @@
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8