[heap] Non-contiguous young generation

This change removes the large contiguous backing store from the young generation
and replaces it regular pages.

We keep a pool of pages that are committed/uncommitted to avoid creating virtual
memory maps during growing and shrinking.

BUG=chromium:581412
LOG=N

Review URL: https://codereview.chromium.org/1853783002

Cr-Commit-Position: refs/heads/master@{#35261}

src/base/platform/platform.h

@@ -291,6 +291,10 @@ class VirtualMemory {
   // by address().
   VirtualMemory(size_t size, size_t alignment);
 
+  // Construct a virtual memory by assigning it some already mapped address
+  // and size.
+  VirtualMemory(void* address, size_t size) : address_(address), size_(size) {}
+
   // Releases the reserved memory, if any, controlled by this VirtualMemory
   // object.
   ~VirtualMemory();

src/heap/heap.cc

@@ -75,7 +75,6 @@ Heap::Heap()
       code_range_size_(0),
       // semispace_size_ should be a power of 2 and old_generation_size_ should
       // be a multiple of Page::kPageSize.
-      reserved_semispace_size_(8 * (kPointerSize / 4) * MB),
       max_semi_space_size_(8 * (kPointerSize / 4) * MB),
       initial_semispace_size_(Page::kPageSize),
       max_old_generation_size_(700ul * (kPointerSize / 4) * MB),
@@ -4915,32 +4914,10 @@ bool Heap::ConfigureHeap(int max_semi_space_size, int max_old_space_size,
     max_semi_space_size_ = Page::kPageSize;
   }
 
-  if (isolate()->snapshot_available()) {
-    // If we are using a snapshot we always reserve the default amount
-    // of memory for each semispace because code in the snapshot has
-    // write-barrier code that relies on the size and alignment of new
-    // space.  We therefore cannot use a larger max semispace size
-    // than the default reserved semispace size.
-    if (max_semi_space_size_ > reserved_semispace_size_) {
-      max_semi_space_size_ = reserved_semispace_size_;
-      if (FLAG_trace_gc) {
-        PrintIsolate(isolate_,
-                     "Max semi-space size cannot be more than %d kbytes\n",
-                     reserved_semispace_size_ >> 10);
-      }
-    }
-  } else {
-    // If we are not using snapshots we reserve space for the actual
-    // max semispace size.
-    reserved_semispace_size_ = max_semi_space_size_;
-  }
-
   // The new space size must be a power of two to support single-bit testing
   // for containment.
   max_semi_space_size_ =
       base::bits::RoundUpToPowerOfTwo32(max_semi_space_size_);
-  reserved_semispace_size_ =
-      base::bits::RoundUpToPowerOfTwo32(reserved_semispace_size_);
 
   if (FLAG_min_semi_space_size > 0) {
     int initial_semispace_size = FLAG_min_semi_space_size * MB;
@@ -5284,7 +5261,7 @@ bool Heap::SetUp() {
   incremental_marking_ = new IncrementalMarking(this);
 
   // Set up new space.
-  if (!new_space_.SetUp(reserved_semispace_size_, max_semi_space_size_)) {
+  if (!new_space_.SetUp(initial_semispace_size_, max_semi_space_size_)) {
     return false;
   }
   new_space_top_after_last_gc_ = new_space()->top();

src/heap/heap.h

@@ -1174,16 +1174,11 @@ class Heap {
   // GC statistics. ============================================================
   // ===========================================================================
 
-  // Returns the maximum amount of memory reserved for the heap.  For
-  // the young generation, we reserve 4 times the amount needed for a
-  // semi space.  The young generation consists of two semi spaces and
-  // we reserve twice the amount needed for those in order to ensure
-  // that new space can be aligned to its size.
+  // Returns the maximum amount of memory reserved for the heap.
   intptr_t MaxReserved() {
-    return 4 * reserved_semispace_size_ + max_old_generation_size_;
+    return 2 * max_semi_space_size_ + max_old_generation_size_;
   }
   int MaxSemiSpaceSize() { return max_semi_space_size_; }
-  int ReservedSemiSpaceSize() { return reserved_semispace_size_; }
   int InitialSemiSpaceSize() { return initial_semispace_size_; }
   intptr_t MaxOldGenerationSize() { return max_old_generation_size_; }
   intptr_t MaxExecutableSize() { return max_executable_size_; }
@@ -1995,10 +1990,8 @@ class Heap {
   Object* roots_[kRootListLength];
 
   size_t code_range_size_;
-  int reserved_semispace_size_;
   int max_semi_space_size_;
   int initial_semispace_size_;
-  int target_semispace_size_;
   intptr_t max_old_generation_size_;
   intptr_t initial_old_generation_size_;
   bool old_generation_size_configured_;

src/heap/spaces-inl.h

@@ -251,6 +251,19 @@ AllocationSpace AllocationResult::RetrySpace() {
   return static_cast<AllocationSpace>(Smi::cast(object_)->value());
 }
 
+NewSpacePage* NewSpacePage::Initialize(Heap* heap, MemoryChunk* chunk,
+                                       Executability executable,
+                                       SemiSpace* owner) {
+  DCHECK_EQ(executable, Executability::NOT_EXECUTABLE);
+  bool in_to_space = (owner->id() != kFromSpace);
+  chunk->SetFlag(in_to_space ? MemoryChunk::IN_TO_SPACE
+                             : MemoryChunk::IN_FROM_SPACE);
+  DCHECK(!chunk->IsFlagSet(in_to_space ? MemoryChunk::IN_FROM_SPACE
+                                       : MemoryChunk::IN_TO_SPACE));
+  NewSpacePage* page = static_cast<NewSpacePage*>(chunk);
+  heap->incremental_marking()->SetNewSpacePageFlags(page);
+  return page;
+}
 
 // --------------------------------------------------------------------------
 // PagedSpace
@@ -261,6 +274,7 @@ Page* Page::Initialize(Heap* heap, MemoryChunk* chunk, Executability executable,
   page->mutex_ = new base::Mutex();
   DCHECK(page->area_size() <= kAllocatableMemory);
   DCHECK(chunk->owner() == owner);
+
   owner->IncreaseCapacity(page->area_size());
   heap->incremental_marking()->SetOldSpacePageFlags(chunk);
 

test/cctest/heap/test-heap.cc

@@ -2333,11 +2333,7 @@ TEST(GrowAndShrinkNewSpace) {
   Heap* heap = CcTest::heap();
   NewSpace* new_space = heap->new_space();
 
-  if (heap->ReservedSemiSpaceSize() == heap->InitialSemiSpaceSize() ||
-      heap->MaxSemiSpaceSize() == heap->InitialSemiSpaceSize()) {
-    // The max size cannot exceed the reserved size, since semispaces must be
-    // always within the reserved space.  We can't test new space growing and
-    // shrinking if the reserved size is the same as the minimum (initial) size.
+  if (heap->MaxSemiSpaceSize() == heap->InitialSemiSpaceSize()) {
     return;
   }
 
@@ -2382,11 +2378,7 @@ TEST(GrowAndShrinkNewSpace) {
 TEST(CollectingAllAvailableGarbageShrinksNewSpace) {
   CcTest::InitializeVM();
   Heap* heap = CcTest::heap();
-  if (heap->ReservedSemiSpaceSize() == heap->InitialSemiSpaceSize() ||
-      heap->MaxSemiSpaceSize() == heap->InitialSemiSpaceSize()) {
-    // The max size cannot exceed the reserved size, since semispaces must be
-    // always within the reserved space.  We can't test new space growing and
-    // shrinking if the reserved size is the same as the minimum (initial) size.
+  if (heap->MaxSemiSpaceSize() == heap->InitialSemiSpaceSize()) {
     return;
   }
 

test/cctest/heap/test-spaces.cc

@@ -317,8 +317,9 @@ TEST(MemoryAllocator) {
   {
     int total_pages = 0;
     OldSpace faked_space(heap, OLD_SPACE, NOT_EXECUTABLE);
-    Page* first_page = memory_allocator->AllocatePage(
-        faked_space.AreaSize(), &faked_space, NOT_EXECUTABLE);
+    Page* first_page = memory_allocator->AllocatePage<Page>(
+        faked_space.AreaSize(), static_cast<PagedSpace*>(&faked_space),
+        NOT_EXECUTABLE);
 
     first_page->InsertAfter(faked_space.anchor()->prev_page());
     CHECK(first_page->is_valid());
@@ -330,8 +331,9 @@ TEST(MemoryAllocator) {
     }
 
     // Again, we should get n or n - 1 pages.
-    Page* other = memory_allocator->AllocatePage(faked_space.AreaSize(),
-                                                 &faked_space, NOT_EXECUTABLE);
+    Page* other = memory_allocator->AllocatePage<Page>(
+        faked_space.AreaSize(), static_cast<PagedSpace*>(&faked_space),
+        NOT_EXECUTABLE);
     CHECK(other->is_valid());
     total_pages++;
     other->InsertAfter(first_page);
@@ -362,8 +364,8 @@ TEST(NewSpace) {
 
   NewSpace new_space(heap);
 
-  CHECK(new_space.SetUp(CcTest::heap()->ReservedSemiSpaceSize(),
-                        CcTest::heap()->ReservedSemiSpaceSize()));
+  CHECK(new_space.SetUp(CcTest::heap()->InitialSemiSpaceSize(),
+                        CcTest::heap()->InitialSemiSpaceSize()));
   CHECK(new_space.HasBeenSetUp());
 
   while (new_space.Available() >= Page::kMaxRegularHeapObjectSize) {