[heap] Make page promotion tests more robust against fragmentation

Bug: chromium:738865
Change-Id: If710b60d33eea94bff7b621910006c2d941a7670
Reviewed-on: https://chromium-review.googlesource.com/571900Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46697}

test/cctest/heap/test-page-promotion.cc

@@ -9,14 +9,13 @@
 // FIXME(mstarzinger, marja): This is weird, but required because of the missing
 // (disallowed) include: src/factory.h -> src/objects-inl.h
 #include "src/objects-inl.h"
-// FIXME(mstarzinger, marja): This is weird, but required because of the missing
-// (disallowed) include: src/feedback-vector.h ->
-// src/feedback-vector-inl.h
-#include "src/feedback-vector-inl.h"
 #include "test/cctest/cctest.h"
 #include "test/cctest/heap/heap-tester.h"
 #include "test/cctest/heap/heap-utils.h"
 
+namespace v8 {
+namespace internal {
+
 namespace {
 
 v8::Isolate* NewIsolateForPagePromotion(int min_semi_space_size = 8,
@@ -24,26 +23,31 @@ v8::Isolate* NewIsolateForPagePromotion(int min_semi_space_size = 8,
   // Parallel evacuation messes with fragmentation in a way that objects that
   // should be copied in semi space are promoted to old space because of
   // fragmentation.
-  i::FLAG_parallel_compaction = false;
-  i::FLAG_page_promotion = true;
-  i::FLAG_page_promotion_threshold = 0;  // %
-  i::FLAG_min_semi_space_size = min_semi_space_size;
+  FLAG_parallel_compaction = false;
+  FLAG_page_promotion = true;
+  FLAG_page_promotion_threshold = 0;
+  FLAG_min_semi_space_size = min_semi_space_size;
   // We cannot optimize for size as we require a new space with more than one
   // page.
-  i::FLAG_optimize_for_size = false;
+  FLAG_optimize_for_size = false;
   // Set max_semi_space_size because it could've been initialized by an
   // implication of optimize_for_size.
-  i::FLAG_max_semi_space_size = max_semi_space_size;
+  FLAG_max_semi_space_size = max_semi_space_size;
   v8::Isolate::CreateParams create_params;
   create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
   v8::Isolate* isolate = v8::Isolate::New(create_params);
   return isolate;
 }
 
-}  // namespace
+Page* FindLastPageInNewSpace(std::vector<Handle<FixedArray>>& handles) {
+  for (auto rit = handles.rbegin(); rit != handles.rend(); ++rit) {
+    Page* candidate = Page::FromAddress((*rit)->address());
+    if (candidate->InNewSpace()) return candidate;
+  }
+  return nullptr;
+}
 
-namespace v8 {
-namespace internal {
+}  // namespace
 
 UNINITIALIZED_TEST(PagePromotion_NewToOld) {
   if (!i::FLAG_incremental_marking) return;
@@ -61,10 +65,8 @@ UNINITIALIZED_TEST(PagePromotion_NewToOld) {
     heap::SimulateFullSpace(heap->new_space(), &handles);
     heap->CollectGarbage(NEW_SPACE, i::GarbageCollectionReason::kTesting);
     CHECK_GT(handles.size(), 0u);
-    // Last object in handles should definitely be on a page that does not
-    // contain the age mark, thus qualifying for moving.
-    Handle<FixedArray> last_object = handles.back();
-    Page* to_be_promoted_page = Page::FromAddress(last_object->address());
+    Page* const to_be_promoted_page = FindLastPageInNewSpace(handles);
+    CHECK_NOT_NULL(to_be_promoted_page);
     CHECK(!to_be_promoted_page->Contains(heap->new_space()->age_mark()));
     // To perform a sanity check on live bytes we need to mark the heap.
     heap::SimulateIncrementalMarking(heap, true);