[heap] Remove/resolve TODOs

Change-Id: Ib6036e38a145153e865059f1aeccc5cdc8c9e840
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2848471Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74158}

src/heap/heap.cc

@@ -2966,8 +2966,6 @@ void* Heap::AllocateExternalBackingStore(
                      GarbageCollectionReason::kExternalMemoryPressure);
     }
   }
-  // TODO(ulan): Perform GCs proactively based on the byte_length and
-  // the current external backing store counters.
   void* result = allocate(byte_length);
   if (result) return result;
   if (!always_allocate()) {
@@ -3061,8 +3059,7 @@ void VerifyNoNeedToClearSlots(Address start, Address end) {
   BasicMemoryChunk* basic_chunk = BasicMemoryChunk::FromAddress(start);
   if (basic_chunk->InReadOnlySpace()) return;
   MemoryChunk* chunk = static_cast<MemoryChunk*>(basic_chunk);
-  // TODO(ulan): Support verification of large pages.
-  if (chunk->InYoungGeneration() || chunk->IsLargePage()) return;
+  if (chunk->InYoungGeneration()) return;
   BaseSpace* space = chunk->owner();
   space->heap()->VerifySlotRangeHasNoRecordedSlots(start, end);
 }
@@ -5955,7 +5952,6 @@ void Heap::VerifyClearedSlot(HeapObject object, ObjectSlot slot) {
 void Heap::VerifySlotRangeHasNoRecordedSlots(Address start, Address end) {
 #ifndef V8_DISABLE_WRITE_BARRIERS
   Page* page = Page::FromAddress(start);
-  DCHECK(!page->IsLargePage());
   DCHECK(!page->InYoungGeneration());
   RememberedSet<OLD_TO_NEW>::CheckNoneInRange(page, start, end);
 #endif

src/heap/heap.h

@@ -2663,7 +2663,6 @@ T ForwardingAddress(T heap_obj) {
   } else if (Heap::InFromPage(heap_obj)) {
     return T();
   } else {
-    // TODO(ulan): Support minor mark-compactor here.
     return heap_obj;
   }
 }

src/heap/mark-compact.cc

@@ -4558,7 +4558,8 @@ void MinorMarkCompactCollector::CollectGarbage() {
     }
     // Since we promote all surviving large objects immediatelly, all remaining
     // large objects must be dead.
-    // TODO(ulan): Don't free all as soon as we have an intermediate generation.
+    // TODO(v8:11685): Don't free all as soon as we have an intermediate
+    // generation.
     heap()->new_lo_space()->FreeDeadObjects([](HeapObject) { return true; });
   }
 

src/heap/sweeper.cc

@@ -351,9 +351,6 @@ int Sweeper::RawSweep(
   size_t live_bytes = 0;
   size_t max_freed_bytes = 0;
 
-  // TODO(ulan): we don't have to clear type old-to-old slots in code space
-  // because the concurrent marker doesn't mark code objects. This requires
-  // the write barrier for code objects to check the color of the code object.
   bool non_empty_typed_slots = p->typed_slot_set<OLD_TO_NEW>() != nullptr ||
                                p->typed_slot_set<OLD_TO_OLD>() != nullptr;