Provide a tagged allocation top pointer.

test/cctest/heap/heap-utils.cc

Index: test/cctest/heap/heap-utils.cc
diff --git a/test/cctest/heap/heap-utils.cc b/test/cctest/heap/heap-utils.cc
index 8abc5c3b5c63d2e863080effda3d2c0a69a2396a..54b7e24588e72d249e6e1518bf8f825a38b8bb2d 100644
--- a/test/cctest/heap/heap-utils.cc
+++ b/test/cctest/heap/heap-utils.cc
@@ -45,8 +45,7 @@ std::vector<Handle<FixedArray>> CreatePadding(Heap* heap, int padding_size,
   } else {
     heap->new_space()->DisableInlineAllocationSteps();
     int overall_free_memory =
-        static_cast<int>(*heap->new_space()->allocation_limit_address() -
-                         *heap->new_space()->allocation_top_address());
+        static_cast<int>(heap->new_space()->limit() - heap->new_space()->top());
     CHECK(padding_size <= overall_free_memory || overall_free_memory == 0);
   }
   while (free_memory > 0) {
@@ -59,9 +58,13 @@ std::vector<Handle<FixedArray>> CreatePadding(Heap* heap, int padding_size,
       if (length <= 0) {
         // Not enough room to create another fixed array. Let's create a filler.
         if (free_memory > (2 * kPointerSize)) {
-          heap->CreateFillerObjectAt(
-              *heap->old_space()->allocation_top_address(), free_memory,
-              ClearRecordedSlots::kNo);
+          if (tenure == i::TENURED) {
+            heap->CreateFillerObjectAt(heap->old_space()->top(), free_memory,
+                                       ClearRecordedSlots::kNo);
+          } else {
+            heap->CreateFillerObjectAt(heap->new_space()->top(), free_memory,
+                                       ClearRecordedSlots::kNo);
+          }
         }
         break;
       }
@@ -77,8 +80,7 @@ std::vector<Handle<FixedArray>> CreatePadding(Heap* heap, int padding_size,
 void AllocateAllButNBytes(v8::internal::NewSpace* space, int extra_bytes,
                           std::vector<Handle<FixedArray>>* out_handles) {
   space->DisableInlineAllocationSteps();
-  int space_remaining = static_cast<int>(*space->allocation_limit_address() -
-                                         *space->allocation_top_address());
+  int space_remaining = static_cast<int>(space->limit() - space->top());
   CHECK(space_remaining >= extra_bytes);
   int new_linear_size = space_remaining - extra_bytes;
   if (new_linear_size == 0) return;
@@ -96,8 +98,7 @@ void FillCurrentPage(v8::internal::NewSpace* space,
 bool FillUpOnePage(v8::internal::NewSpace* space,
                    std::vector<Handle<FixedArray>>* out_handles) {
   space->DisableInlineAllocationSteps();
-  int space_remaining = static_cast<int>(*space->allocation_limit_address() -
-                                         *space->allocation_top_address());
+  int space_remaining = static_cast<int>(space->limit() - space->top());
   if (space_remaining == 0) return false;
   std::vector<Handle<FixedArray>> handles =
       heap::CreatePadding(space->heap(), space_remaining, i::NOT_TENURED);
@@ -156,6 +157,13 @@ void GcAndSweep(Heap* heap, AllocationSpace space) {
   }
 }
 
+void MakeSureNewSpaceTopIsNotDoubleAligned(i::Heap* heap) {
+  intptr_t top = reinterpret_cast<intptr_t>(heap->new_space()->top());
+  if ((top & kDoubleAlignmentMaskTagged) == 0) {
+    CreatePadding(heap, kDoubleSize / 2, NOT_TENURED);
+  }
+}
+
 }  // namespace heap
 }  // namespace internal
 }  // namespace v8