Fix Heap::IsHeapIterable.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index a63fd65d4bc6b2298a08bcdad7a62e160867ede8..6e50c980294c73f70f81cea18184a34e13a37332 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -13126,14 +13126,6 @@ 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);
@@ -13151,6 +13143,10 @@ RUNTIME_FUNCTION(Runtime_DebugReferencedBy) {
 
   // 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,
@@ -13160,8 +13156,7 @@ RUNTIME_FUNCTION(Runtime_DebugReferencedBy) {
   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,
@@ -13216,9 +13211,6 @@ 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);
@@ -13227,6 +13219,10 @@ RUNTIME_FUNCTION(Runtime_DebugConstructedBy) {
 
   // 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,
@@ -13237,8 +13233,8 @@ RUNTIME_FUNCTION(Runtime_DebugConstructedBy) {
   // 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,