[heap] Remove references to semi spaces from heap.cc

This includes:
1) Inline UncommintFromSpace into Shrink (always called together)
2) Replace ZapFromSpace with virtual ZapUnusedMemory
3) Replace EnsureFromSpaceIsCommited with virtual Prologue

Bug: v8:12612
Change-Id: I934479761c877e10734f54e6d5896a4741b92ef7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3650738Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80563}

src/heap/heap.cc

@@ -1028,11 +1028,6 @@ void Heap::IncrementDeferredCount(v8::Isolate::UseCounterFeature feature) {
   deferred_counters_[feature]++;
 }
 
-void Heap::UncommitFromSpace() {
-  DCHECK_NOT_NULL(new_space_);
-  SemiSpaceNewSpace::From(new_space_)->UncommitFromSpace();
-}
-
 void Heap::GarbageCollectionPrologue(
     GarbageCollectionReason gc_reason,
     const v8::GCCallbackFlags gc_callback_flags) {
@@ -1454,11 +1449,10 @@ void Heap::GarbageCollectionEpilogueInSafepoint(GarbageCollector collector) {
   if (FLAG_check_handle_count) CheckHandleCount();
 #endif
 
-  if (Heap::ShouldZapGarbage() || FLAG_clear_free_memory) {
-    ZapFromSpace();
-  }
-
   if (new_space()) {
+    if (Heap::ShouldZapGarbage() || FLAG_clear_free_memory) {
+      new_space()->ZapUnusedMemory();
+    }
     TRACE_GC(tracer(), GCTracer::Scope::HEAP_EPILOGUE_REDUCE_NEW_SPACE);
     ReduceNewSpaceSize();
   }
@@ -2173,11 +2167,6 @@ void Heap::CopyRange(HeapObject dst_object, const TSlot dst_slot,
   WriteBarrierForRange(dst_object, dst_slot, dst_end);
 }
 
-void Heap::EnsureFromSpaceIsCommitted() {
-  if (!new_space_) return;
-  SemiSpaceNewSpace::From(new_space_)->CommitFromSpaceIfNeeded();
-}
-
 bool Heap::CollectionRequested() {
   return collection_barrier_->WasGCRequested();
 }
@@ -2305,7 +2294,7 @@ size_t Heap::PerformGarbageCollection(
 
   GarbageCollectionPrologueInSafepoint();
 
-  EnsureFromSpaceIsCommitted();
+  if (new_space()) new_space()->Prologue();
 
   size_t start_young_generation_size =
       NewSpaceSize() + (new_lo_space() ? new_lo_space()->SizeOfObjects() : 0);
@@ -3821,7 +3810,6 @@ void Heap::ReduceNewSpaceSize() {
        (allocation_throughput < kLowAllocationThroughput))) {
     new_space_->Shrink();
     new_lo_space_->SetCapacity(new_space_->Capacity());
-    UncommitFromSpace();
   }
 }
 
@@ -4856,18 +4844,6 @@ void Heap::VerifyCommittedPhysicalMemory() {
 }
 #endif  // DEBUG
 
-void Heap::ZapFromSpace() {
-  if (!new_space_) return;
-  SemiSpaceNewSpace* semi_space_new_space = SemiSpaceNewSpace::From(new_space_);
-  if (!semi_space_new_space->IsFromSpaceCommitted()) return;
-  for (Page* page :
-       PageRange(semi_space_new_space->from_space().first_page(), nullptr)) {
-    memory_allocator()->ZapBlock(page->area_start(),
-                                 page->HighWaterMark() - page->area_start(),
-                                 ZapValue());
-  }
-}
-
 void Heap::ZapCodeObject(Address start_address, int size_in_bytes) {
 #ifdef DEBUG
   DCHECK(IsAligned(start_address, kIntSize));

src/heap/heap.h

@@ -1819,15 +1819,6 @@ class Heap {
   void CreateInternalAccessorInfoObjects();
   void CreateInitialObjects();
 
-  // Commits from space if it is uncommitted.
-  void EnsureFromSpaceIsCommitted();
-
-  // Uncommit unused semi space.
-  V8_EXPORT_PRIVATE void UncommitFromSpace();
-
-  // Fill in bogus values in from space
-  void ZapFromSpace();
-
   // Zaps the memory of a code object.
   V8_EXPORT_PRIVATE void ZapCodeObject(Address start_address,
                                        int size_in_bytes);

src/heap/new-spaces.cc

@@ -629,6 +629,8 @@ void SemiSpaceNewSpace::Shrink() {
     from_space_.ShrinkTo(rounded_new_capacity);
   }
   DCHECK_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
+  if (!from_space_.IsCommitted()) return;
+  from_space_.Uncommit();
 }
 
 size_t SemiSpaceNewSpace::CommittedPhysicalMemory() const {
@@ -818,6 +820,14 @@ size_t SemiSpaceNewSpace::AllocatedSinceLastGC() const {
   return allocated;
 }
 
+void SemiSpaceNewSpace::Prologue() {
+  if (from_space_.IsCommitted() || from_space_.Commit()) return;
+
+  // Committing memory to from space failed.
+  // Memory is exhausted and we will die.
+  heap_->FatalProcessOutOfMemory("Committing semi space failed.");
+}
+
 void SemiSpaceNewSpace::EvacuatePrologue() {
   // Flip the semispaces.  After flipping, to space is empty, from space has
   // live objects.
@@ -825,5 +835,14 @@ void SemiSpaceNewSpace::EvacuatePrologue() {
   ResetLinearAllocationArea();
 }
 
+void SemiSpaceNewSpace::ZapUnusedMemory() {
+  if (!IsFromSpaceCommitted()) return;
+  for (Page* page : PageRange(from_space().first_page(), nullptr)) {
+    heap_->memory_allocator()->ZapBlock(
+        page->area_start(), page->HighWaterMark() - page->area_start(),
+        heap_->ZapValue());
+  }
+}
+
 }  // namespace internal
 }  // namespace v8

src/heap/new-spaces.h

@@ -308,8 +308,12 @@ class NewSpace : NON_EXPORTED_BASE(public SpaceWithLinearArea) {
 
   virtual bool AddFreshPage() = 0;
 
+  virtual void Prologue() {}
+
   virtual void EvacuatePrologue() = 0;
 
+  virtual void ZapUnusedMemory() {}
+
  protected:
   static const int kAllocationBufferParkingThreshold = 4 * KB;
 
@@ -464,20 +468,6 @@ class V8_EXPORT_PRIVATE SemiSpaceNewSpace final : public NewSpace {
   void Print() override { to_space_.Print(); }
 #endif
 
-  // Return whether the operation succeeded.
-  bool CommitFromSpaceIfNeeded() {
-    if (from_space_.IsCommitted() || from_space_.Commit()) return true;
-
-    // Committing memory to from space failed.
-    // Memory is exhausted and we will die.
-    heap_->FatalProcessOutOfMemory("Committing semi space failed.");
-  }
-
-  void UncommitFromSpace() {
-    if (!from_space_.IsCommitted()) return;
-    from_space_.Uncommit();
-  }
-
   bool IsFromSpaceCommitted() const { return from_space_.IsCommitted(); }
 
   SemiSpace* active_space() { return &to_space_; }
@@ -503,8 +493,12 @@ class V8_EXPORT_PRIVATE SemiSpaceNewSpace final : public NewSpace {
 
   bool ShouldBePromoted(Address address) const final;
 
+  void Prologue() final;
+
   void EvacuatePrologue() final;
 
+  void ZapUnusedMemory() final;
+
  private:
   // Reset the allocation pointer to the beginning of the active semispace.
   void ResetLinearAllocationArea();

test/cctest/heap/heap-tester.h

@@ -116,7 +116,7 @@ class HeapTester {
   static AllocationResult AllocateFixedArrayForTest(Heap* heap, int length,
                                                     AllocationType allocation);
 
-  static void UncommitFromSpace(Heap* heap);
+  static void UncommitUnusedMemory(Heap* heap);
 };
 
 }  // namespace heap

test/cctest/heap/test-heap.cc

@@ -7114,8 +7114,8 @@ UNINITIALIZED_TEST(RestoreHeapLimit) {
   reinterpret_cast<v8::Isolate*>(isolate)->Dispose();
 }
 
-void HeapTester::UncommitFromSpace(Heap* heap) {
-  heap->UncommitFromSpace();
+void HeapTester::UncommitUnusedMemory(Heap* heap) {
+  heap->new_space()->Shrink();
   heap->memory_allocator()->unmapper()->EnsureUnmappingCompleted();
 }
 

test/cctest/heap/test-weak-references.cc

@@ -622,7 +622,7 @@ TEST(Regress7768) {
 
   // Make sure the memory where it's stored is invalidated, so that we'll crash
   // if we try to access it.
-  HeapTester::UncommitFromSpace(heap);
+  HeapTester::UncommitUnusedMemory(heap);
 
   // This used to crash when processing the dead weak reference.
   CcTest::CollectAllGarbage();