[heap] Use PagedNewSpace when MinorMC is enabled

This CL also introduces/updates DCHECKs that some methods are never
reached with MinorMC (they may still be reached by full GC when MinorMC
is disabled).

Bug: v8:12612
Change-Id: I8afb8c964bc5c44225a92d0f8d9ac5a4c0ecef75
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3823130Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82439}

src/heap/heap-inl.h

@@ -63,6 +63,7 @@ T ForwardingAddress(T heap_obj) {
   if (map_word.IsForwardingAddress()) {
     return T::cast(map_word.ToForwardingAddress());
   } else if (Heap::InFromPage(heap_obj)) {
+    DCHECK(!FLAG_minor_mc);
     return T();
   } else {
     return heap_obj;
@@ -410,8 +411,9 @@ void Heap::UpdateAllocationSite(Map map, HeapObject object,
   DCHECK_NE(pretenuring_feedback, &global_pretenuring_feedback_);
 #ifdef DEBUG
   BasicMemoryChunk* chunk = BasicMemoryChunk::FromHeapObject(object);
-  DCHECK_IMPLIES(chunk->IsToPage(),
-                 chunk->IsFlagSet(MemoryChunk::PAGE_NEW_NEW_PROMOTION));
+  DCHECK_IMPLIES(
+      chunk->IsToPage(),
+      FLAG_minor_mc || chunk->IsFlagSet(MemoryChunk::PAGE_NEW_NEW_PROMOTION));
   DCHECK_IMPLIES(!chunk->InYoungGeneration(),
                  chunk->IsFlagSet(MemoryChunk::PAGE_NEW_OLD_PROMOTION));
 #endif

src/heap/heap.cc

@@ -930,6 +930,9 @@ void Heap::PrintRetainingPath(HeapObject target, RetainingPathOption option) {
 
 void UpdateRetainersMapAfterScavenge(
     std::unordered_map<HeapObject, HeapObject, Object::Hasher>* map) {
+  // This is only used for Scavenger.
+  DCHECK(!FLAG_minor_mc);
+
   std::unordered_map<HeapObject, HeapObject, Object::Hasher> updated_map;
 
   for (auto pair : *map) {
@@ -957,7 +960,7 @@ void UpdateRetainersMapAfterScavenge(
 void Heap::UpdateRetainersAfterScavenge() {
   if (!incremental_marking()->IsMarking()) return;
 
-  // This isn't supported for Minor MC.
+  // This is only used for Scavenger.
   DCHECK(!FLAG_minor_mc);
 
   UpdateRetainersMapAfterScavenge(&retainer_);
@@ -2598,11 +2601,6 @@ void Heap::MinorMarkCompact() {
   CHECK_EQ(NOT_IN_GC, gc_state());
   DCHECK(new_space());
 
-  if (FLAG_trace_incremental_marking && !incremental_marking()->IsStopped()) {
-    isolate()->PrintWithTimestamp(
-        "[IncrementalMarking] MinorMarkCompact during marking.\n");
-  }
-
   PauseAllocationObserversScope pause_observers(this);
   SetGCState(MINOR_MARK_COMPACT);
 
@@ -2775,6 +2773,9 @@ void Heap::UpdateExternalString(String string, size_t old_payload,
 
 String Heap::UpdateYoungReferenceInExternalStringTableEntry(Heap* heap,
                                                             FullObjectSlot p) {
+  // This is only used for Scavenger.
+  DCHECK(!FLAG_minor_mc);
+
   PtrComprCageBase cage_base(heap->isolate());
   HeapObject obj = HeapObject::cast(*p);
   MapWord first_word = obj.map_word(cage_base, kRelaxedLoad);
@@ -4781,6 +4782,11 @@ void Heap::VerifyCommittedPhysicalMemory() {
        space = spaces.Next()) {
     space->VerifyCommittedPhysicalMemory();
   }
+  if (FLAG_minor_mc && new_space()) {
+    PagedNewSpace::From(new_space())
+        ->paged_space()
+        ->VerifyCommittedPhysicalMemory();
+  }
 }
 #endif  // DEBUG
 
@@ -5757,9 +5763,15 @@ void Heap::SetUpSpaces(LinearAllocationArea& new_allocation_info,
   DCHECK_NOT_NULL(read_only_space_);
   const bool has_young_gen = !FLAG_single_generation && !IsShared();
   if (has_young_gen) {
-    space_[NEW_SPACE] = new_space_ =
-        new SemiSpaceNewSpace(this, initial_semispace_size_,
-                              max_semi_space_size_, new_allocation_info);
+    if (FLAG_minor_mc) {
+      space_[NEW_SPACE] = new_space_ =
+          new PagedNewSpace(this, initial_semispace_size_, max_semi_space_size_,
+                            new_allocation_info);
+    } else {
+      space_[NEW_SPACE] = new_space_ =
+          new SemiSpaceNewSpace(this, initial_semispace_size_,
+                                max_semi_space_size_, new_allocation_info);
+    }
     space_[NEW_LO_SPACE] = new_lo_space_ =
         new NewLargeObjectSpace(this, NewSpaceCapacity());
   }
@@ -5918,6 +5930,7 @@ void Heap::NotifyOldGenerationExpansion(AllocationSpace space,
                                         MemoryChunk* chunk) {
   // Pages created during bootstrapping may contain immortal immovable objects.
   if (!deserialization_complete()) {
+    DCHECK_NE(NEW_SPACE, chunk->owner()->identity());
     chunk->MarkNeverEvacuate();
   }
   if (space == CODE_SPACE || space == CODE_LO_SPACE) {

src/heap/incremental-marking.cc

@@ -378,6 +378,7 @@ void IncrementalMarking::UpdateMarkingWorklistAfterYoungGenGC() {
     DCHECK(obj.IsHeapObject());
     // Only pointers to from space have to be updated.
     if (Heap::InFromPage(obj)) {
+      DCHECK(!FLAG_minor_mc);
       MapWord map_word = obj.map_word(cage_base, kRelaxedLoad);
       if (!map_word.IsForwardingAddress()) {
         // There may be objects on the marking deque that do not exist
@@ -401,6 +402,11 @@ void IncrementalMarking::UpdateMarkingWorklistAfterYoungGenGC() {
       // new space.
       DCHECK(Heap::IsLargeObject(obj) || Page::FromHeapObject(obj)->IsFlagSet(
                                              Page::PAGE_NEW_NEW_PROMOTION));
+      DCHECK_IMPLIES(FLAG_minor_mc, !Page::FromHeapObject(obj)->IsFlagSet(
+                                        Page::PAGE_NEW_NEW_PROMOTION));
+      DCHECK_IMPLIES(
+          FLAG_minor_mc,
+          !obj.map_word(cage_base, kRelaxedLoad).IsForwardingAddress());
       if (minor_marking_state->IsWhite(obj)) {
         return false;
       }

src/heap/mark-compact.cc

@@ -137,7 +137,7 @@ class MarkingVerifier : public ObjectVisitorWithCageBases, public RootVisitor {
   void VerifyRoots();
   void VerifyMarkingOnPage(const Page* page, Address start, Address end);
   void VerifyMarking(NewSpace* new_space);
-  void VerifyMarking(PagedSpace* paged_space);
+  void VerifyMarking(PagedSpaceBase* paged_space);
   void VerifyMarking(LargeObjectSpace* lo_space);
 
   Heap* heap_;
@@ -177,6 +177,10 @@ void MarkingVerifier::VerifyMarkingOnPage(const Page* page, Address start,
 
 void MarkingVerifier::VerifyMarking(NewSpace* space) {
   if (!space) return;
+  if (FLAG_minor_mc) {
+    VerifyMarking(PagedNewSpace::From(space)->paged_space());
+    return;
+  }
   Address end = space->top();
   // The bottom position is at the start of its page. Allows us to use
   // page->area_start() as start of range on all pages.
@@ -192,7 +196,7 @@ void MarkingVerifier::VerifyMarking(NewSpace* space) {
   }
 }
 
-void MarkingVerifier::VerifyMarking(PagedSpace* space) {
+void MarkingVerifier::VerifyMarking(PagedSpaceBase* space) {
   for (Page* p : *space) {
     VerifyMarkingOnPage(p, p->area_start(), p->area_end());
   }
@@ -344,7 +348,7 @@ class EvacuationVerifier : public ObjectVisitorWithCageBases,
   void VerifyRoots();
   void VerifyEvacuationOnPage(Address start, Address end);
   void VerifyEvacuation(NewSpace* new_space);
-  void VerifyEvacuation(PagedSpace* paged_space);
+  void VerifyEvacuation(PagedSpaceBase* paged_space);
 
   Heap* heap_;
 };
@@ -367,6 +371,10 @@ void EvacuationVerifier::VerifyEvacuationOnPage(Address start, Address end) {
 
 void EvacuationVerifier::VerifyEvacuation(NewSpace* space) {
   if (!space) return;
+  if (FLAG_minor_mc) {
+    VerifyEvacuation(PagedNewSpace::From(space)->paged_space());
+    return;
+  }
   PageRange range(space->first_allocatable_address(), space->top());
   for (auto it = range.begin(); it != range.end();) {
     Page* page = *(it++);
@@ -377,7 +385,7 @@ void EvacuationVerifier::VerifyEvacuation(NewSpace* space) {
   }
 }
 
-void EvacuationVerifier::VerifyEvacuation(PagedSpace* space) {
+void EvacuationVerifier::VerifyEvacuation(PagedSpaceBase* space) {
   for (Page* p : *space) {
     if (p->IsEvacuationCandidate()) continue;
     if (p->Contains(space->top())) {
@@ -645,7 +653,7 @@ void MarkCompactCollector::VerifyMarkbitsAreDirty(ReadOnlySpace* space) {
   }
 }
 
-void MarkCompactCollector::VerifyMarkbitsAreClean(PagedSpace* space) {
+void MarkCompactCollector::VerifyMarkbitsAreClean(PagedSpaceBase* space) {
   for (Page* p : *space) {
     CHECK(non_atomic_marking_state()->bitmap(p)->IsClean());
     CHECK_EQ(0, non_atomic_marking_state()->live_bytes(p));
@@ -654,6 +662,10 @@ void MarkCompactCollector::VerifyMarkbitsAreClean(PagedSpace* space) {
 
 void MarkCompactCollector::VerifyMarkbitsAreClean(NewSpace* space) {
   if (!space) return;
+  if (FLAG_minor_mc) {
+    VerifyMarkbitsAreClean(PagedNewSpace::From(space)->paged_space());
+    return;
+  }
   for (Page* p : PageRange(space->first_allocatable_address(), space->top())) {
     CHECK(non_atomic_marking_state()->bitmap(p)->IsClean());
     CHECK_EQ(0, non_atomic_marking_state()->live_bytes(p));
@@ -1024,9 +1036,12 @@ void MarkCompactCollector::Prepare() {
     heap()->new_lo_space()->ResetPendingObject();
   }
 
-  if (heap()->new_space()) {
-    DCHECK_EQ(heap()->new_space()->top(),
-              heap()->new_space()->original_top_acquire());
+  NewSpace* new_space = heap()->new_space();
+  if (new_space) {
+    if (FLAG_minor_mc) {
+      PagedNewSpace::From(new_space)->paged_space()->PrepareForMarkCompact();
+    }
+    DCHECK_EQ(new_space->top(), new_space->original_top_acquire());
   }
 }
 
@@ -1058,6 +1073,10 @@ void MarkCompactCollector::VerifyMarking() {
     heap()->old_space()->VerifyLiveBytes();
     if (heap()->map_space()) heap()->map_space()->VerifyLiveBytes();
     heap()->code_space()->VerifyLiveBytes();
+    if (FLAG_minor_mc && heap()->new_space())
+      PagedNewSpace::From(heap()->new_space())
+          ->paged_space()
+          ->VerifyLiveBytes();
   }
 #endif
 }
@@ -1626,9 +1645,10 @@ class RecordMigratedSlotVisitor : public ObjectVisitorWithCageBases {
     if (value->IsStrongOrWeak()) {
       BasicMemoryChunk* p = BasicMemoryChunk::FromAddress(value.ptr());
       if (p->InYoungGeneration()) {
-        DCHECK_IMPLIES(
-            p->IsToPage(),
-            p->IsFlagSet(Page::PAGE_NEW_NEW_PROMOTION) || p->IsLargePage());
+        DCHECK_IMPLIES(p->IsToPage(),
+                       FLAG_minor_mc ||
+                           p->IsFlagSet(Page::PAGE_NEW_NEW_PROMOTION) ||
+                           p->IsLargePage());
 
         MemoryChunk* chunk = MemoryChunk::FromHeapObject(host);
         DCHECK(chunk->SweepingDone());
@@ -1777,7 +1797,8 @@ class EvacuateVisitorBase : public HeapObjectVisitor {
     AllocationResult allocation;
     if (ShouldPromoteIntoSharedHeap(map)) {
       DCHECK_EQ(target_space, OLD_SPACE);
-      DCHECK(Heap::InYoungGeneration(object));
+      // TODO(v8:12612): Implement promotion from new space to shared heap.
+      DCHECK_IMPLIES(!FLAG_minor_mc, Heap::InYoungGeneration(object));
       DCHECK_NOT_NULL(shared_old_allocator_);
       allocation = shared_old_allocator_->AllocateRaw(size, alignment,
                                                       AllocationOrigin::kGC);
@@ -1880,6 +1901,9 @@ class EvacuateNewSpaceVisitor final : public EvacuateVisitorBase {
 
     if (heap_->new_space()->ShouldBePromoted(object.address()) &&
         TryEvacuateObject(OLD_SPACE, object, size, &target_object)) {
+      // Full GCs use AlwaysPromoteYoung::kYes above and MinorMC should never
+      // move objects.
+      DCHECK(!FLAG_minor_mc);
       promoted_size_ += size;
       return true;
     }
@@ -1899,7 +1923,7 @@ class EvacuateNewSpaceVisitor final : public EvacuateVisitorBase {
 
  private:
   inline bool TryEvacuateWithoutCopy(HeapObject object) {
-    if (is_incremental_marking_) return false;
+    DCHECK(!is_incremental_marking_);
 
     Map map = object.map();
 
@@ -1966,6 +1990,7 @@ class EvacuateNewSpacePageVisitor final : public HeapObjectVisitor {
   static void Move(Page* page) {
     switch (mode) {
       case NEW_TO_NEW:
+        DCHECK(!FLAG_minor_mc);
         page->heap()->new_space()->PromotePageInNewSpace(page);
         break;
       case NEW_TO_OLD: {
@@ -3559,7 +3584,7 @@ static inline void UpdateSlot(PtrComprCageBase cage_base, TSlot slot,
                 "expected here");
   MapWord map_word = heap_obj.map_word(cage_base, kRelaxedLoad);
   if (map_word.IsForwardingAddress()) {
-    DCHECK_IMPLIES(!Heap::InFromPage(heap_obj),
+    DCHECK_IMPLIES((!FLAG_minor_mc && !Heap::InFromPage(heap_obj)),
                    MarkCompactCollector::IsOnEvacuationCandidate(heap_obj) ||
                        Page::FromHeapObject(heap_obj)->IsFlagSet(
                            Page::COMPACTION_WAS_ABORTED));
@@ -5551,9 +5576,10 @@ class YoungGenerationRecordMigratedSlotVisitor final
     if (value->IsStrongOrWeak()) {
       BasicMemoryChunk* p = BasicMemoryChunk::FromAddress(value.ptr());
       if (p->InYoungGeneration()) {
-        DCHECK_IMPLIES(
-            p->IsToPage(),
-            p->IsFlagSet(Page::PAGE_NEW_NEW_PROMOTION) || p->IsLargePage());
+        DCHECK_IMPLIES(p->IsToPage(),
+                       FLAG_minor_mc ||
+                           p->IsFlagSet(Page::PAGE_NEW_NEW_PROMOTION) ||
+                           p->IsLargePage());
         MemoryChunk* chunk = MemoryChunk::FromHeapObject(host);
         DCHECK(chunk->SweepingDone());
         RememberedSet<OLD_TO_NEW>::Insert<AccessMode::NON_ATOMIC>(chunk, slot);

src/heap/mark-compact.h

@@ -504,7 +504,7 @@ class MarkCompactCollector final : public CollectorBase {
 #ifdef VERIFY_HEAP
   void VerifyMarkbitsAreClean();
   void VerifyMarkbitsAreDirty(ReadOnlySpace* space);
-  void VerifyMarkbitsAreClean(PagedSpace* space);
+  void VerifyMarkbitsAreClean(PagedSpaceBase* space);
   void VerifyMarkbitsAreClean(NewSpace* space);
   void VerifyMarkbitsAreClean(LargeObjectSpace* space);
 #endif

src/heap/new-spaces.cc

@@ -909,10 +909,9 @@ PagedSpaceForNewSpace::PagedSpaceForNewSpace(
       target_capacity_(initial_capacity_) {
   DCHECK_LE(initial_capacity_, max_capacity_);
 
-  // Adding entries to the free list requires having a map for free space. Not
-  // preallocating pages yet because the map may not be available yet when the
-  // space is initialized. `EnsureCurrentCapacity()` should be called after maps
-  // are allocated to preallocate pages.
+  if (!PreallocatePages()) {
+    V8::FatalProcessOutOfMemory(heap->isolate(), "New space setup");
+  }
 }
 
 Page* PagedSpaceForNewSpace::InitializePage(MemoryChunk* chunk) {
@@ -997,10 +996,9 @@ bool PagedSpaceForNewSpace::AddFreshPage() {
   return EnsureCurrentCapacity();
 }
 
-bool PagedSpaceForNewSpace::EnsureCurrentCapacity() {
+bool PagedSpaceForNewSpace::PreallocatePages() {
   // Verify that the free space map is already initialized. Otherwise, new free
   // list entries will be invalid.
-  DCHECK_NE(0, heap()->isolate()->root(RootIndex::kFreeSpaceMap).ptr());
   while (current_capacity_ < target_capacity_) {
     if (!TryExpandImpl()) return false;
   }
@@ -1008,6 +1006,13 @@ bool PagedSpaceForNewSpace::EnsureCurrentCapacity() {
   return true;
 }
 
+bool PagedSpaceForNewSpace::EnsureCurrentCapacity() {
+  // Verify that the free space map is already initialized. Otherwise, new free
+  // list entries will be invalid.
+  DCHECK_NE(0, heap()->isolate()->root(RootIndex::kFreeSpaceMap).ptr());
+  return PreallocatePages();
+}
+
 void PagedSpaceForNewSpace::FreeLinearAllocationArea() {
   size_t remaining_allocation_area_size = limit() - top();
   DCHECK_GE(allocated_linear_areas_, remaining_allocation_area_size);

src/heap/new-spaces.h

@@ -350,6 +350,7 @@ class NewSpace : NON_EXPORTED_BASE(public SpaceWithLinearArea) {
 class V8_EXPORT_PRIVATE SemiSpaceNewSpace final : public NewSpace {
  public:
   static SemiSpaceNewSpace* From(NewSpace* space) {
+    DCHECK(!FLAG_minor_mc);
     return static_cast<SemiSpaceNewSpace*>(space);
   }
 
@@ -628,6 +629,8 @@ class V8_EXPORT_PRIVATE PagedSpaceForNewSpace final : public PagedSpaceBase {
 #endif  // V8_ENABLE_INNER_POINTER_RESOLUTION_OSB
 
  private:
+  bool PreallocatePages();
+
   const size_t initial_capacity_;
   const size_t max_capacity_;
   size_t target_capacity_ = 0;
@@ -642,6 +645,7 @@ class V8_EXPORT_PRIVATE PagedSpaceForNewSpace final : public PagedSpaceBase {
 class V8_EXPORT_PRIVATE PagedNewSpace final : public NewSpace {
  public:
   static PagedNewSpace* From(NewSpace* space) {
+    DCHECK(FLAG_minor_mc);
     return static_cast<PagedNewSpace*>(space);
   }
 

src/heap/paged-spaces.cc

@@ -184,6 +184,7 @@ void PagedSpaceBase::MergeCompactionSpace(CompactionSpace* other) {
   base::MutexGuard guard(mutex());
 
   DCHECK_NE(NEW_SPACE, identity());
+  DCHECK_NE(NEW_SPACE, other->identity());
   DCHECK(identity() == other->identity());
 
   // Unmerged fields:
@@ -325,6 +326,9 @@ void PagedSpaceBase::RemovePage(Page* page) {
   DCHECK_IMPLIES(identity() == NEW_SPACE, page->IsFlagSet(Page::TO_PAGE));
   memory_chunk_list_.Remove(page);
   UnlinkFreeListCategories(page);
+  if (identity() == NEW_SPACE) {
+    page->ReleaseFreeListCategories();
+  }
   DecreaseAllocatedBytes(page->allocated_bytes(), page);
   DecreaseCapacity(page->area_size());
   AccountUncommitted(page->size());
@@ -359,6 +363,7 @@ void PagedSpaceBase::ResetFreeList() {
     free_list_->EvictFreeListItems(page);
   }
   DCHECK(free_list_->IsEmpty());
+  DCHECK_EQ(0, free_list_->Available());
 }
 
 void PagedSpaceBase::ShrinkImmortalImmovablePages() {
@@ -504,7 +509,7 @@ void PagedSpaceBase::FreeLinearAllocationArea() {
 
   AdvanceAllocationObservers();
 
-  if (current_top != current_limit &&
+  if (identity() != NEW_SPACE && current_top != current_limit &&
       heap()->incremental_marking()->black_allocation()) {
     Page::FromAddress(current_top)
         ->DestroyBlackArea(current_top, current_limit);

src/heap/setup-heap-internal.cc

@@ -8,6 +8,7 @@
 #include "src/execution/protectors.h"
 #include "src/heap/factory.h"
 #include "src/heap/heap-inl.h"
+#include "src/heap/new-spaces.h"
 #include "src/ic/handler-configuration.h"
 #include "src/init/heap-symbols.h"
 #include "src/init/setup-isolate.h"
@@ -74,6 +75,12 @@ bool SetupIsolateDelegate::SetupHeapInternal(Heap* heap) {
 bool Heap::CreateHeapObjects() {
   // Create initial maps.
   if (!CreateInitialMaps()) return false;
+  if (FLAG_minor_mc && new_space()) {
+    PagedNewSpace::From(new_space())
+        ->paged_space()
+        ->free_list()
+        ->RepairLists(this);
+  }
   CreateApiObjects();
 
   // Create initial objects

src/objects/string-table.cc

@@ -928,6 +928,8 @@ void StringForwardingTable::Block::UpdateAfterEvacuation(Isolate* isolate) {
 
 void StringForwardingTable::Block::UpdateAfterEvacuation(Isolate* isolate,
                                                          int up_to_index) {
+  // This is only used for Scavenger.
+  DCHECK(!FLAG_minor_mc);
   DCHECK(FLAG_always_use_string_forwarding_table);
   for (int index = 0; index < up_to_index; ++index) {
     Object original = Get(isolate, IndexOfOriginalString(index));