[heap,snapshot] Replace first page size from snapshots with page trimming

test/cctest/heap/test-spaces.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 18 matching lines @@
 
 #include "src/base/platform/platform.h"
 #include "src/heap/spaces-inl.h"
 // FIXME(mstarzinger, marja): This is weird, but required because of the missing
 // (disallowed) include: src/heap/incremental-marking.h -> src/objects-inl.h
 #include "src/objects-inl.h"
 #include "src/snapshot/snapshot.h"
 #include "src/v8.h"
 #include "test/cctest/cctest.h"
 #include "test/cctest/heap/heap-tester.h"
+#include "test/cctest/heap/heap-utils.h"
 
 namespace v8 {
 namespace internal {
 
 #if 0
 static void VerifyRegionMarking(Address page_start) {
 #ifdef ENABLE_CARDMARKING_WRITE_BARRIER
   Page* p = Page::FromAddress(page_start);
 
   p->SetRegionMarks(Page::kAllRegionsCleanMarks);
@@ skipping 426 matching lines @@
     // The available value is conservative such that it may report
     // zero prior to heap exhaustion.
     CHECK(lo->Available() < available || available == 0);
   }
 
   CHECK(!lo->IsEmpty());
 
   CHECK(lo->AllocateRaw(lo_size, NOT_EXECUTABLE).IsRetry());
 }
 
-
-TEST(SizeOfFirstPageIsLargeEnough) {
+TEST(SizeOfInitialHeap) {
   if (i::FLAG_always_opt) return;
   // Bootstrapping without a snapshot causes more allocations.
   CcTest::InitializeVM();
   Isolate* isolate = CcTest::i_isolate();
   if (!isolate->snapshot_available()) return;
   HandleScope scope(isolate);
   v8::Local<v8::Context> context = CcTest::isolate()->GetCurrentContext();
   // Skip this test on the custom snapshot builder.
   if (!CcTest::global()
            ->Get(context, v8_str("assertEquals"))
            .ToLocalChecked()
            ->IsUndefined()) {
     return;
   }
 
-  // If this test fails due to enabling experimental natives that are not part
-  // of the snapshot, we may need to adjust CalculateFirstPageSizes.
+  // The limit for each space for an empty isolate containing just the
+  // snapshot.
+  const size_t kMaxInitialSizePerSpace = 2 * MB;
 
-  // Freshly initialized VM gets by with one page per space.
+  // Freshly initialized VM gets by with the snapshot size (which is below
+  // kMaxInitialSizePerSpace per space).
+  Heap* heap = isolate->heap();
+  int page_count[LAST_PAGED_SPACE + 1] = {0, 0, 0, 0};
   for (int i = FIRST_PAGED_SPACE; i <= LAST_PAGED_SPACE; i++) {
     // Debug code can be very large, so skip CODE_SPACE if we are generating it.
     if (i == CODE_SPACE && i::FLAG_debug_code) continue;
-    CHECK_EQ(1, isolate->heap()->paged_space(i)->CountTotalPages());
+
+    page_count[i] = heap->paged_space(i)->CountTotalPages();
+    // Check that the initial heap is also below the limit.
+    CHECK_LT(static_cast<size_t>(heap->paged_space(i)->CommittedMemory()),
+             kMaxInitialSizePerSpace);
   }
 
-  // Executing the empty script gets by with one page per space.
+  // Executing the empty script gets by with the same number of pages, i.e.,
+  // requires no extra space.
   CompileRun("/*empty*/");
   for (int i = FIRST_PAGED_SPACE; i <= LAST_PAGED_SPACE; i++) {
     // Debug code can be very large, so skip CODE_SPACE if we are generating it.
     if (i == CODE_SPACE && i::FLAG_debug_code) continue;
-    CHECK_EQ(1, isolate->heap()->paged_space(i)->CountTotalPages());
+    CHECK_EQ(page_count[i], isolate->heap()->paged_space(i)->CountTotalPages());
   }
 
   // No large objects required to perform the above steps.
   CHECK(isolate->heap()->lo_space()->IsEmpty());
 }
 
 static HeapObject* AllocateUnaligned(NewSpace* space, int size) {
   AllocationResult allocation = space->AllocateRawUnaligned(size);
   CHECK(!allocation.IsRetry());
   HeapObject* filler = NULL;
@@ skipping 150 matching lines @@
 
     new_space->RemoveAllocationObserver(&observer1);
     new_space->RemoveAllocationObserver(&observer2);
 
     CHECK_EQ(observer1.count(), 32);
     CHECK_EQ(observer2.count(), 28);
   }
   isolate->Dispose();
 }
 
+TEST(ShrinkPageToHighWaterMarkFreeSpaceEnd) {
+  CcTest::InitializeVM();
+  Isolate* isolate = CcTest::i_isolate();
+  HandleScope scope(isolate);
+
+  heap::SealCurrentObjects(CcTest::heap());
+
+  // Prepare page that only contains a single object and a trailing FreeSpace
+  // filler.
+  Handle<FixedArray> array = isolate->factory()->NewFixedArray(128, TENURED);
+  Page* page = Page::FromAddress(array->address());
+
+  // Reset space so high water mark is consistent.
+  CcTest::heap()->old_space()->ResetFreeList();
+  CcTest::heap()->old_space()->EmptyAllocationInfo();
+
+  HeapObject* filler =
+      HeapObject::FromAddress(array->address() + array->Size());
+  CHECK(filler->IsFreeSpace());
+  size_t shrinked = page->ShrinkToHighWaterMark();
+  size_t should_have_shrinked =
+      RoundDown(static_cast<size_t>(Page::kAllocatableMemory - array->Size()),
+                base::OS::CommitPageSize());
+  CHECK_EQ(should_have_shrinked, shrinked);
+}
+
+TEST(ShrinkPageToHighWaterMarkNoFiller) {
+  CcTest::InitializeVM();
+  Isolate* isolate = CcTest::i_isolate();
+  HandleScope scope(isolate);
+  heap::SealCurrentObjects(CcTest::heap());
+
+  const int kFillerSize = 0;
+  std::vector<Handle<FixedArray>> arrays =
+      heap::FillOldSpacePageWithFixedArrays(CcTest::heap(), kFillerSize);
+  Handle<FixedArray> array = arrays.back();
+  Page* page = Page::FromAddress(array->address());
+  CHECK_EQ(page->area_end(), array->address() + array->Size() + kFillerSize);
+
+  // Reset space so high water mark and fillers are consistent.
+  CcTest::heap()->old_space()->ResetFreeList();
+  CcTest::heap()->old_space()->EmptyAllocationInfo();
+
+  const size_t shrinked = page->ShrinkToHighWaterMark();
+  CHECK_EQ(0, shrinked);
+}
+
+TEST(ShrinkPageToHighWaterMarkOneWordFiller) {
+  CcTest::InitializeVM();
+  Isolate* isolate = CcTest::i_isolate();
+  HandleScope scope(isolate);
+
+  heap::SealCurrentObjects(CcTest::heap());
+
+  const int kFillerSize = kPointerSize;
+  std::vector<Handle<FixedArray>> arrays =
+      heap::FillOldSpacePageWithFixedArrays(CcTest::heap(), kFillerSize);
+  Handle<FixedArray> array = arrays.back();
+  Page* page = Page::FromAddress(array->address());
+  CHECK_EQ(page->area_end(), array->address() + array->Size() + kFillerSize);
+
+  // Reset space so high water mark and fillers are consistent.
+  CcTest::heap()->old_space()->ResetFreeList();
+  CcTest::heap()->old_space()->EmptyAllocationInfo();
+
+  HeapObject* filler =
+      HeapObject::FromAddress(array->address() + array->Size());
+  CHECK_EQ(filler->map(), CcTest::heap()->one_pointer_filler_map());
+
+  const size_t shrinked = page->ShrinkToHighWaterMark();
+  CHECK_EQ(0, shrinked);
+}
+
+TEST(ShrinkPageToHighWaterMarkTwoWordFiller) {
+  CcTest::InitializeVM();
+  Isolate* isolate = CcTest::i_isolate();
+  HandleScope scope(isolate);
+
+  heap::SealCurrentObjects(CcTest::heap());
+
+  const int kFillerSize = 2 * kPointerSize;
+  std::vector<Handle<FixedArray>> arrays =
+      heap::FillOldSpacePageWithFixedArrays(CcTest::heap(), kFillerSize);
+  Handle<FixedArray> array = arrays.back();
+  Page* page = Page::FromAddress(array->address());
+  CHECK_EQ(page->area_end(), array->address() + array->Size() + kFillerSize);
+
+  // Reset space so high water mark and fillers are consistent.
+  CcTest::heap()->old_space()->ResetFreeList();
+  CcTest::heap()->old_space()->EmptyAllocationInfo();
+
+  HeapObject* filler =
+      HeapObject::FromAddress(array->address() + array->Size());
+  CHECK_EQ(filler->map(), CcTest::heap()->two_pointer_filler_map());
+
+  const size_t shrinked = page->ShrinkToHighWaterMark();
+  CHECK_EQ(0, shrinked);
+}
+
 }  // namespace internal
 }  // namespace v8