Added a promotion queue unit test that test promotion queue memory corruption

by semi-space evacuation.

BUG=
R=titzer@chromium.org

Review URL: https://codereview.chromium.org/362723003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22134 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/heap.cc

@@ -1950,6 +1950,19 @@ class ScavengingVisitor : public StaticVisitorBase {
                                    HeapObject* source,
                                    HeapObject* target,
                                    int size)) {
+    // If we migrate into to-space, then the to-space top pointer should be
+    // right after the target object. Incorporate double alignment
+    // over-allocation.
+    ASSERT(!heap->InToSpace(target) ||
+        target->address() + size == heap->new_space()->top() ||
+        target->address() + size + kPointerSize == heap->new_space()->top());
+
+    // Make sure that we do not overwrite the promotion queue which is at
+    // the end of to-space.
+    ASSERT(!heap->InToSpace(target) ||
+        heap->promotion_queue()->IsBelowPromotionQueue(
+            heap->new_space()->top()));
+
     // Copy the content of source to target.
     heap->CopyBlock(target->address(), source->address(), size);
 

src/heap.h

@@ -427,6 +427,18 @@ class PromotionQueue {
     RelocateQueueHead();
   }
 
+  bool IsBelowPromotionQueue(Address to_space_top) {
+    // If the given to-space top pointer and the head of the promotion queue
+    // are not on the same page, then the to-space objects are below the
+    // promotion queue.
+    if (GetHeadPage() != Page::FromAddress(to_space_top)) {
+      return true;
+    }
+    // If the to space top pointer is smaller or equal than the promotion
+    // queue head, then the to-space objects are below the promotion queue.
+    return reinterpret_cast<intptr_t*>(to_space_top) <= rear_;
+  }
+
   bool is_empty() {
     return (front_ == rear_) &&
         (emergency_stack_ == NULL || emergency_stack_->length() == 0);

test/cctest/test-heap.cc

@@ -4329,6 +4329,81 @@ TEST(ArrayShiftSweeping) {
 }
 
 
+TEST(PromotionQueue) {
+  i::FLAG_expose_gc = true;
+  i::FLAG_max_semi_space_size = 2;
+  CcTest::InitializeVM();
+  v8::HandleScope scope(CcTest::isolate());
+  Isolate* isolate = CcTest::i_isolate();
+  Heap* heap = isolate->heap();
+  NewSpace* new_space = heap->new_space();
+
+  // In this test we will try to overwrite the promotion queue which is at the
+  // end of to-space. To actually make that possible, we need at least two
+  // semi-space pages and take advantage of fragementation.
+  // (1) Grow semi-space to two pages.
+  // (2) Create a few small long living objects and call the scavenger to
+  // move them to the other semi-space.
+  // (3) Create a huge object, i.e., remainder of first semi-space page and
+  // create another huge object which should be of maximum allocatable memory
+  // size of the second semi-space page.
+  // (4) Call the scavenger again.
+  // What will happen is: the scavenger will promote the objects created in (2)
+  // and will create promotion queue entries at the end of the second
+  // semi-space page during the next scavenge when it promotes the objects to
+  // the old generation. The first allocation of (3) will fill up the first
+  // semi-space page. The second allocation in (3) will not fit into the first
+  // semi-space page, but it will overwrite the promotion queue which are in
+  // the second semi-space page. If the right guards are in place, the promotion
+  // queue will be evacuated in that case.
+
+  // Grow the semi-space to two pages to make semi-space copy overwrite the
+  // promotion queue, which will be at the end of the second page.
+  intptr_t old_capacity = new_space->Capacity();
+  new_space->Grow();
+  CHECK(new_space->IsAtMaximumCapacity());
+  CHECK(2 * old_capacity == new_space->Capacity());
+
+  // Call the scavenger two times to get an empty new space
+  heap->CollectGarbage(NEW_SPACE);
+  heap->CollectGarbage(NEW_SPACE);
+
+  // First create a few objects which will survive a scavenge, and will get
+  // promoted to the old generation later on. These objects will create
+  // promotion queue entries at the end of the second semi-space page.
+  const int number_handles = 12;
+  Handle<FixedArray> handles[number_handles];
+  for (int i = 0; i < number_handles; i++) {
+    handles[i] = isolate->factory()->NewFixedArray(1, NOT_TENURED);
+  }
+  heap->CollectGarbage(NEW_SPACE);
+
+  // Create the first huge object which will exactly fit the first semi-space
+  // page.
+  int new_linear_size = static_cast<int>(
+      *heap->new_space()->allocation_limit_address() -
+          *heap->new_space()->allocation_top_address());
+  int length = new_linear_size / kPointerSize - FixedArray::kHeaderSize;
+  Handle<FixedArray> first =
+    isolate->factory()->NewFixedArray(length, NOT_TENURED);
+  CHECK(heap->InNewSpace(*first));
+
+  // Create the second huge object of maximum allocatable second semi-space
+  // page size.
+  new_linear_size = static_cast<int>(
+      *heap->new_space()->allocation_limit_address() -
+          *heap->new_space()->allocation_top_address());
+  length = Page::kMaxRegularHeapObjectSize / kPointerSize -
+      FixedArray::kHeaderSize;
+  Handle<FixedArray> second =
+      isolate->factory()->NewFixedArray(length, NOT_TENURED);
+  CHECK(heap->InNewSpace(*second));
+
+  // This scavenge will corrupt memory if the promotion queue is not evacuated.
+  heap->CollectGarbage(NEW_SPACE);
+}
+
+
 #ifdef DEBUG
 TEST(PathTracer) {
   CcTest::InitializeVM();