Fix Heap::IsHeapIterable.

src/runtime.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 <stdlib.h>
 #include <limits>
 
 #include "v8.h"
 
 #include "accessors.h"
@@ skipping 13108 matching lines @@
 
 
 // Scan the heap for objects with direct references to an object
 // args[0]: the object to find references to
 // args[1]: constructor function for instances to exclude (Mirror)
 // args[2]: the the maximum number of objects to return
 RUNTIME_FUNCTION(Runtime_DebugReferencedBy) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 3);
 
-  // First perform a full GC in order to avoid references from dead objects.
-  Heap* heap = isolate->heap();
-  heap->CollectAllGarbage(Heap::kMakeHeapIterableMask, "%DebugReferencedBy");
-  // The heap iterator reserves the right to do a GC to make the heap iterable.
-  // Due to the GC above we know it won't need to do that, but it seems cleaner
-  // to get the heap iterator constructed before we start having unprotected
-  // Object* locals that are not protected by handles.
-
   // Check parameters.
   CONVERT_ARG_HANDLE_CHECKED(JSObject, target, 0);
   CONVERT_ARG_HANDLE_CHECKED(Object, instance_filter, 1);
   RUNTIME_ASSERT(instance_filter->IsUndefined() ||
                  instance_filter->IsJSObject());
   CONVERT_NUMBER_CHECKED(int32_t, max_references, Int32, args[2]);
   RUNTIME_ASSERT(max_references >= 0);
 
 
   // Get the constructor function for context extension and arguments array.
   Handle<JSObject> arguments_boilerplate(
       isolate->context()->native_context()->sloppy_arguments_boilerplate());
   Handle<JSFunction> arguments_function(
       JSFunction::cast(arguments_boilerplate->map()->constructor()));
 
   // Get the number of referencing objects.
   int count;
+  // First perform a full GC in order to avoid dead objects and to make the heap
+  // iterable.
+  Heap* heap = isolate->heap();
+  heap->CollectAllGarbage(Heap::kMakeHeapIterableMask, "%DebugConstructedBy");

[Hannes Payer (out of office), 2014/05/18 18:25:43]

Call MakeIterable instead.

[Jarin, 2014/05/19 06:06:42]

I think this should still call CollectAllGarbage because we need the garbage
collection to discard dead objects. MakeHeapIterable does not guarantee there
will be GC.

   HeapIterator heap_iterator(heap);
   count = DebugReferencedBy(&heap_iterator,
                             *target, *instance_filter, max_references,
                             NULL, 0, *arguments_function);
 
   // Allocate an array to hold the result.
   Handle<FixedArray> instances = isolate->factory()->NewFixedArray(count);
 
   // Fill the referencing objects.
-  // AllocateFixedArray above does not make the heap non-iterable.
-  ASSERT(heap->IsHeapIterable());
+  heap->EnsureHeapIsIterable();
   HeapIterator heap_iterator2(heap);
   count = DebugReferencedBy(&heap_iterator2,
                             *target, *instance_filter, max_references,
                             *instances, count, *arguments_function);
 
   // Return result as JS array.
   Handle<JSFunction> constructor(
       isolate->context()->native_context()->array_function());
 
   Handle<JSObject> result = isolate->factory()->NewJSObject(constructor);
@@ skipping 34 matching lines @@
 }
 
 
 // Scan the heap for objects constructed by a specific function.
 // args[0]: the constructor to find instances of
 // args[1]: the the maximum number of objects to return
 RUNTIME_FUNCTION(Runtime_DebugConstructedBy) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 2);
 
-  // First perform a full GC in order to avoid dead objects.
-  Heap* heap = isolate->heap();
-  heap->CollectAllGarbage(Heap::kMakeHeapIterableMask, "%DebugConstructedBy");
 
   // Check parameters.
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, constructor, 0);
   CONVERT_NUMBER_CHECKED(int32_t, max_references, Int32, args[1]);
   RUNTIME_ASSERT(max_references >= 0);
 
   // Get the number of referencing objects.
   int count;
+  // First perform a full GC in order to avoid dead objects and to make the heap
+  // iterable.
+  Heap* heap = isolate->heap();
+  heap->CollectAllGarbage(Heap::kMakeHeapIterableMask, "%DebugConstructedBy");

[Hannes Payer (out of office), 2014/05/18 18:25:43]

Call MakeIterable instead.

[Jarin, 2014/05/19 06:06:42]

See above.

   HeapIterator heap_iterator(heap);
   count = DebugConstructedBy(&heap_iterator,
                              *constructor,
                              max_references,
                              NULL,
                              0);
 
   // Allocate an array to hold the result.
   Handle<FixedArray> instances = isolate->factory()->NewFixedArray(count);
 
-  ASSERT(heap->IsHeapIterable());
   // Fill the referencing objects.
+  heap->EnsureHeapIsIterable();
   HeapIterator heap_iterator2(heap);
   count = DebugConstructedBy(&heap_iterator2,
                              *constructor,
                              max_references,
                              *instances,
                              count);
 
   // Return result as JS array.
   Handle<JSFunction> array_function(
       isolate->context()->native_context()->array_function());
@@ skipping 1976 matching lines @@
   }
   return NULL;
 }
 
 
 const Runtime::Function* Runtime::FunctionForId(Runtime::FunctionId id) {
   return &(kIntrinsicFunctions[static_cast<int>(id)]);
 }
 
 } }  // namespace v8::internal