cppgc: Polish custom spaces

Bug: chromium:1056170
Change-Id: I778dc23c82e8cfda34559e5e2e7515a73010a9d7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2192656Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67700}

src/heap/cppgc/raw-heap.cc

@@ -12,8 +12,7 @@ namespace internal {
 // static
 constexpr size_t RawHeap::kNumberOfRegularSpaces;
 
-RawHeap::RawHeap(Heap* heap, size_t custom_spaces)
-    : main_heap_(heap), custom_spaces_(custom_spaces) {
+RawHeap::RawHeap(Heap* heap, size_t custom_spaces) : main_heap_(heap) {
   size_t i = 0;
   for (; i < static_cast<size_t>(RegularSpaceType::kLarge); ++i) {
     spaces_.push_back(std::make_unique<NormalPageSpace>(this, i));

src/heap/cppgc/raw-heap.h

@@ -30,8 +30,8 @@ class V8_EXPORT_PRIVATE RawHeap final {
   //
   // Objects of size greater than 2^16 get stored in the large space.
   //
-  // Users can override where objects are allocated via Heap::SpacePolicy and
-  // force allocation in one of the kUserDefined* spaces.
+  // Users can override where objects are allocated via cppgc::CustomSpace to
+  // force allocation in a custom space.
   enum class RegularSpaceType : uint8_t {
     kNormal1,
     kNormal2,
@@ -60,11 +60,10 @@ class V8_EXPORT_PRIVATE RawHeap final {
   iterator custom_end() { return end(); }
 
   size_t size() const { return spaces_.size(); }
-  size_t custom_spaces() const { return custom_spaces_; }
 
   BaseSpace* Space(RegularSpaceType type) {
     const size_t index = static_cast<size_t>(type);
-    DCHECK_GT(spaces_.size(), index);
+    DCHECK_GT(kNumberOfRegularSpaces, index);
     BaseSpace* space = spaces_[index].get();
     DCHECK(space);
     return space;
@@ -83,8 +82,8 @@ class V8_EXPORT_PRIVATE RawHeap final {
     return const_cast<RawHeap&>(*this).Space(space_index);
   }
 
-  size_t SpaceIndexForCustomSpace(CustomSpaceIndex space_index) {
-    DCHECK_LT(space_index, custom_spaces_);
+  size_t SpaceIndexForCustomSpace(CustomSpaceIndex space_index) const {
+    DCHECK_LT(space_index, spaces_.size() - kNumberOfRegularSpaces);
     return kNumberOfRegularSpaces + space_index;
   }
 
@@ -94,7 +93,6 @@ class V8_EXPORT_PRIVATE RawHeap final {
  private:
   Heap* main_heap_;
   Spaces spaces_;
-  size_t custom_spaces_;
 };
 
 }  // namespace internal

src/heap/cppgc/sweeper.cc

@@ -24,7 +24,6 @@ namespace {
 struct SpaceState {
   BaseSpace::Pages unswept_pages;
 };
-// using SpaceStates = std::array<SpaceState, RawHeap::kMaxNumberOfSpaces>;
 using SpaceStates = std::vector<SpaceState>;
 
 bool SweepNormalPage(NormalPage* page) {