Revision: 21387
Author:   [email protected]
Date:     Tue May 20 13:19:21 2014 UTC
Log:      Fix Heap::IsHeapIterable.

We only consider heap iterable if the new space is empty (in addition to the exisiting old space check).

The change also moves the iterability forcing + allocation prevention gadgets to HeapIterator so that it is impossible to miss them when iterating the heap.

[email protected]
BUG=373283
LOG=N

Review URL: https://codereview.chromium.org/285693006
http://code.google.com/p/v8/source/detail?r=21387

Added:
 /branches/bleeding_edge/test/mjsunit/regress/regress-373283.js
Modified:
 /branches/bleeding_edge/src/debug.cc
 /branches/bleeding_edge/src/heap-profiler.cc
 /branches/bleeding_edge/src/heap-snapshot-generator.cc
 /branches/bleeding_edge/src/heap.cc
 /branches/bleeding_edge/src/heap.h
 /branches/bleeding_edge/src/liveedit.cc
 /branches/bleeding_edge/src/runtime.cc
 /branches/bleeding_edge/test/cctest/test-api.cc
 /branches/bleeding_edge/test/cctest/test-heap.cc
 /branches/bleeding_edge/test/cctest/test-object-observe.cc

=======================================
--- /dev/null
+++ /branches/bleeding_edge/test/mjsunit/regress/regress-373283.js Tue May 20 13:19:21 2014 UTC
@@ -0,0 +1,18 @@
+// Copyright 2014 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.
+
+// Flags:  --allow-natives-syntax --deopt-every-n-times=1
+
+function __f_0() {
+  var x = [];
+  x[21] = 1;
+  x[21] + 0;
+}
+
+for (var i = 0; i < 3; i++) __f_0();
+%OptimizeFunctionOnNextCall(__f_0);
+for (var i = 0; i < 10; i++) __f_0();
+%OptimizeFunctionOnNextCall(__f_0);
+__f_0();
+%GetScript("foo");
=======================================
--- /branches/bleeding_edge/src/debug.cc        Tue May 20 08:52:42 2014 UTC
+++ /branches/bleeding_edge/src/debug.cc        Tue May 20 13:19:21 2014 UTC
@@ -2048,6 +2048,7 @@
       Heap* heap = isolate_->heap();
       heap->CollectAllGarbage(Heap::kMakeHeapIterableMask,
                               "preparing for breakpoints");
+      HeapIterator iterator(heap);

       // Ensure no GC in this scope as we are going to use gc_metadata
       // field in the Code object to mark active functions.
@@ -2067,7 +2068,6 @@
       // Scan the heap for all non-optimized functions which have no
       // debug break slots and are not active or inlined into an active
       // function and mark them for lazy compilation.
-      HeapIterator iterator(heap);
       HeapObject* obj = NULL;
       while (((obj = iterator.next()) != NULL)) {
         if (obj->IsJSFunction()) {
@@ -2192,9 +2192,7 @@
   Handle<SharedFunctionInfo> target;
   Heap* heap = isolate_->heap();
   while (!done) {
-    { // Extra scope for iterator and no-allocation.
-      heap->EnsureHeapIsIterable();
-      DisallowHeapAllocation no_alloc_during_heap_iteration;
+    { // Extra scope for iterator.
       HeapIterator iterator(heap);
       for (HeapObject* obj = iterator.next();
            obj != NULL; obj = iterator.next()) {
@@ -2524,8 +2522,6 @@
// scripts which are no longer referenced. The second also sweeps precisely,
   // which saves us doing yet another GC to make the heap iterable.
   heap->CollectAllGarbage(Heap::kNoGCFlags, "Debug::CreateScriptCache");
-  heap->CollectAllGarbage(Heap::kMakeHeapIterableMask,
-                          "Debug::CreateScriptCache");

   ASSERT(script_cache_ == NULL);
   script_cache_ = new ScriptCache(isolate_);
@@ -2533,7 +2529,6 @@
   // Scan heap for Script objects.
   int count = 0;
   HeapIterator iterator(heap);
-  DisallowHeapAllocation no_allocation;

for (HeapObject* obj = iterator.next(); obj != NULL; obj = iterator.next()) {
     if (obj->IsScript() && Script::cast(obj)->HasValidSource()) {
=======================================
--- /branches/bleeding_edge/src/heap-profiler.cc Tue Apr 29 06:42:26 2014 UTC +++ /branches/bleeding_edge/src/heap-profiler.cc Tue May 20 13:19:21 2014 UTC
@@ -173,9 +173,6 @@


 Handle<HeapObject> HeapProfiler::FindHeapObjectById(SnapshotObjectId id) {
-  heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask,
-                            "HeapProfiler::FindHeapObjectById");
-  DisallowHeapAllocation no_allocation;
   HeapObject* object = NULL;
   HeapIterator iterator(heap(), HeapIterator::kFilterUnreachable);
   // Make sure that object with the given id is still reachable.
=======================================
--- /branches/bleeding_edge/src/heap-snapshot-generator.cc Wed Apr 30 12:25:18 2014 UTC +++ /branches/bleeding_edge/src/heap-snapshot-generator.cc Tue May 20 13:19:21 2014 UTC
@@ -2569,10 +2569,6 @@
   CHECK(!debug_heap->map_space()->was_swept_conservatively());
 #endif

-  // The following code uses heap iterators, so we want the heap to be
-  // stable. It should follow TagGlobalObjects as that can allocate.
-  DisallowHeapAllocation no_alloc;
-
 #ifdef VERIFY_HEAP
   debug_heap->Verify();
 #endif
=======================================
--- /branches/bleeding_edge/src/heap.cc Tue May 20 09:53:18 2014 UTC
+++ /branches/bleeding_edge/src/heap.cc Tue May 20 13:19:21 2014 UTC
@@ -4321,14 +4321,15 @@

 bool Heap::IsHeapIterable() {
   return (!old_pointer_space()->was_swept_conservatively() &&
-          !old_data_space()->was_swept_conservatively());
+          !old_data_space()->was_swept_conservatively() &&
+          new_space()->bottom() == new_space()->top());
 }


-void Heap::EnsureHeapIsIterable() {
+void Heap::MakeHeapIterable() {
   ASSERT(AllowHeapAllocation::IsAllowed());
   if (!IsHeapIterable()) {
-    CollectAllGarbage(kMakeHeapIterableMask, "Heap::EnsureHeapIsIterable");
+    CollectAllGarbage(kMakeHeapIterableMask, "Heap::MakeHeapIterable");
   }
   ASSERT(IsHeapIterable());
 }
@@ -5732,7 +5733,9 @@


 HeapIterator::HeapIterator(Heap* heap)
-    : heap_(heap),
+    : make_heap_iterable_helper_(heap),
+      no_heap_allocation_(),
+      heap_(heap),
       filtering_(HeapIterator::kNoFiltering),
       filter_(NULL) {
   Init();
@@ -5741,7 +5744,9 @@

 HeapIterator::HeapIterator(Heap* heap,
                            HeapIterator::HeapObjectsFiltering filtering)
-    : heap_(heap),
+    : make_heap_iterable_helper_(heap),
+      no_heap_allocation_(),
+      heap_(heap),
       filtering_(filtering),
       filter_(NULL) {
   Init();
=======================================
--- /branches/bleeding_edge/src/heap.h  Tue May 20 09:53:18 2014 UTC
+++ /branches/bleeding_edge/src/heap.h  Tue May 20 13:19:21 2014 UTC
@@ -767,7 +767,7 @@

   // Ensure that we have swept all spaces in such a way that we can iterate
   // over all objects.  May cause a GC.
-  void EnsureHeapIsIterable();
+  void MakeHeapIterable();

   // Notify the heap that a context has been disposed.
   int NotifyContextDisposed();
@@ -2391,6 +2391,9 @@
 // aggregates the specific iterators for the different spaces as
 // these can only iterate over one space only.
 //
+// HeapIterator ensures there is no allocation during its lifetime
+// (using an embedded DisallowHeapAllocation instance).
+//
 // HeapIterator can skip free list nodes (that is, de-allocated heap
 // objects that still remain in the heap). As implementation of free
 // nodes filtering uses GC marks, it can't be used during MS/MC GC
@@ -2413,12 +2416,18 @@
   void reset();

  private:
+  struct MakeHeapIterableHelper {
+ explicit MakeHeapIterableHelper(Heap* heap) { heap->MakeHeapIterable(); }
+  };
+
   // Perform the initialization.
   void Init();
   // Perform all necessary shutdown (destruction) work.
   void Shutdown();
   HeapObject* NextObject();

+  MakeHeapIterableHelper make_heap_iterable_helper_;
+  DisallowHeapAllocation no_heap_allocation_;
   Heap* heap_;
   HeapObjectsFiltering filtering_;
   HeapObjectsFilter* filter_;
=======================================
--- /branches/bleeding_edge/src/liveedit.cc     Tue May  6 16:02:18 2014 UTC
+++ /branches/bleeding_edge/src/liveedit.cc     Tue May 20 13:19:21 2014 UTC
@@ -939,13 +939,10 @@
   // to code objects (that are never in new space) without worrying about
   // write barriers.
   Heap* heap = original->GetHeap();
-  heap->CollectAllGarbage(Heap::kMakeHeapIterableMask,
-                          "liveedit.cc ReplaceCodeObject");
+  HeapIterator iterator(heap);

   ASSERT(!heap->InNewSpace(*substitution));

-  DisallowHeapAllocation no_allocation;
-
   ReplacingVisitor visitor(*original, *substitution);

// Iterate over all roots. Stack frames may have pointer into original code,
@@ -955,7 +952,6 @@

   // Now iterate over all pointers of all objects, including code_target
   // implicit pointers.
-  HeapIterator iterator(heap);
for (HeapObject* obj = iterator.next(); obj != NULL; obj = iterator.next()) {
     obj->Iterate(&visitor);
   }
@@ -1019,8 +1015,6 @@
   template<typename Visitor>
   static void IterateJSFunctions(SharedFunctionInfo* shared_info,
                                  Visitor* visitor) {
-    DisallowHeapAllocation no_allocation;
-
     HeapIterator iterator(shared_info->GetHeap());
     for (HeapObject* obj = iterator.next(); obj != NULL;
         obj = iterator.next()) {
@@ -1165,7 +1159,7 @@

   Handle<SharedFunctionInfo> shared_info = shared_info_wrapper.GetInfo();

-  isolate->heap()->EnsureHeapIsIterable();
+  isolate->heap()->MakeHeapIterable();

   if (IsJSFunctionCode(shared_info->code())) {
     Handle<Code> code = compile_info_wrapper.GetFunctionCode();
@@ -1402,7 +1396,7 @@
   info->set_end_position(new_function_end);
   info->set_function_token_position(new_function_token_pos);

-  info->GetIsolate()->heap()->EnsureHeapIsIterable();
+  info->GetIsolate()->heap()->MakeHeapIterable();

   if (IsJSFunctionCode(info->code())) {
     // Patch relocation info section of the code.
=======================================
--- /branches/bleeding_edge/src/runtime.cc      Tue May 20 08:52:42 2014 UTC
+++ /branches/bleeding_edge/src/runtime.cc      Tue May 20 13:19:21 2014 UTC
@@ -13129,14 +13129,6 @@
   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);
@@ -13154,21 +13146,27 @@

   // Get the number of referencing objects.
   int count;
-  HeapIterator heap_iterator(heap);
-  count = DebugReferencedBy(&heap_iterator,
-                            *target, *instance_filter, max_references,
-                            NULL, 0, *arguments_function);
+ // 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");
+  {
+    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());
-  HeapIterator heap_iterator2(heap);
-  count = DebugReferencedBy(&heap_iterator2,
-                            *target, *instance_filter, max_references,
-                            *instances, count, *arguments_function);
+  {
+    HeapIterator heap_iterator(heap);
+    count = DebugReferencedBy(&heap_iterator,
+                              *target, *instance_filter, max_references,
+                              *instances, count, *arguments_function);
+  }

   // Return result as JS array.
   Handle<JSFunction> constructor(
@@ -13219,9 +13217,6 @@
   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);
@@ -13230,24 +13225,31 @@

   // Get the number of referencing objects.
   int count;
-  HeapIterator heap_iterator(heap);
-  count = DebugConstructedBy(&heap_iterator,
-                             *constructor,
-                             max_references,
-                             NULL,
-                             0);
+ // 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");
+  {
+    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.
-  HeapIterator heap_iterator2(heap);
-  count = DebugConstructedBy(&heap_iterator2,
-                             *constructor,
-                             max_references,
-                             *instances,
-                             count);
+  {
+    HeapIterator heap_iterator2(heap);
+    count = DebugConstructedBy(&heap_iterator2,
+                               *constructor,
+                               max_references,
+                               *instances,
+                               count);
+  }

   // Return result as JS array.
   Handle<JSFunction> array_function(
@@ -13379,8 +13381,6 @@
   int number;
   Heap* heap = isolate->heap();
   {
-    heap->EnsureHeapIsIterable();
-    DisallowHeapAllocation no_allocation;
     HeapIterator heap_iterator(heap);
     Script* scr = *script;
     FixedArray* arr = *array;
@@ -13388,8 +13388,6 @@
   }
   if (number > kBufferSize) {
     array = isolate->factory()->NewFixedArray(number);
-    heap->EnsureHeapIsIterable();
-    DisallowHeapAllocation no_allocation;
     HeapIterator heap_iterator(heap);
     Script* scr = *script;
     FixedArray* arr = *array;
@@ -14472,8 +14470,6 @@
   Handle<Script> script;
   Factory* factory = script_name->GetIsolate()->factory();
   Heap* heap = script_name->GetHeap();
-  heap->EnsureHeapIsIterable();
-  DisallowHeapAllocation no_allocation_during_heap_iteration;
   HeapIterator iterator(heap);
   HeapObject* obj = NULL;
   while (script.is_null() && ((obj = iterator.next()) != NULL)) {
=======================================
--- /branches/bleeding_edge/test/cctest/test-api.cc Tue May 20 08:24:51 2014 UTC +++ /branches/bleeding_edge/test/cctest/test-api.cc Tue May 20 13:19:21 2014 UTC
@@ -13514,7 +13514,6 @@


 static int GetGlobalObjectsCount() {
-  CcTest::heap()->EnsureHeapIsIterable();
   int count = 0;
   i::HeapIterator it(CcTest::heap());
for (i::HeapObject* object = it.next(); object != NULL; object = it.next())
=======================================
--- /branches/bleeding_edge/test/cctest/test-heap.cc Wed May 14 11:43:21 2014 UTC +++ /branches/bleeding_edge/test/cctest/test-heap.cc Tue May 20 13:19:21 2014 UTC
@@ -890,7 +890,6 @@
static int ObjectsFoundInHeap(Heap* heap, Handle<Object> objs[], int size) {
   // Count the number of objects found in the heap.
   int found_count = 0;
-  heap->EnsureHeapIsIterable();
   HeapIterator iterator(heap);
for (HeapObject* obj = iterator.next(); obj != NULL; obj = iterator.next()) {
     for (int i = 0; i < size; i++) {
@@ -1629,9 +1628,8 @@

 TEST(TestSizeOfObjectsVsHeapIteratorPrecision) {
   CcTest::InitializeVM();
-  CcTest::heap()->EnsureHeapIsIterable();
-  intptr_t size_of_objects_1 = CcTest::heap()->SizeOfObjects();
   HeapIterator iterator(CcTest::heap());
+  intptr_t size_of_objects_1 = CcTest::heap()->SizeOfObjects();
   intptr_t size_of_objects_2 = 0;
   for (HeapObject* obj = iterator.next();
        obj != NULL;
=======================================
--- /branches/bleeding_edge/test/cctest/test-object-observe.cc Fri May 2 21:29:15 2014 UTC +++ /branches/bleeding_edge/test/cctest/test-object-observe.cc Tue May 20 13:19:21 2014 UTC
@@ -616,7 +616,6 @@


 static int GetGlobalObjectsCount() {
-  CcTest::heap()->EnsureHeapIsIterable();
   int count = 0;
   i::HeapIterator it(CcTest::heap());
for (i::HeapObject* object = it.next(); object != NULL; object = it.next())

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