[heap] Cleanup: Remove various from/to space helpers.

Change-Id: I4cb2e72fdc008ee855014d703af33d2e937bada3
Reviewed-on: https://chromium-review.googlesource.com/1070148
Commit-Queue: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53392}

src/heap/array-buffer-tracker.cc

@@ -80,8 +80,8 @@ void LocalArrayBufferTracker::Process(Callback callback) {
 
 void ArrayBufferTracker::PrepareToFreeDeadInNewSpace(Heap* heap) {
   DCHECK_EQ(heap->gc_state(), Heap::HeapState::SCAVENGE);
-  for (Page* page : PageRange(heap->new_space()->FromSpaceStart(),
-                              heap->new_space()->FromSpaceEnd())) {
+  for (Page* page :
+       PageRange(heap->new_space()->from_space().first_page(), nullptr)) {
     bool empty = ProcessBuffers(page, kUpdateForwardedRemoveOthers);
     CHECK(empty);
   }

src/heap/heap.cc

@@ -1979,7 +1979,7 @@ void Heap::EvacuateYoungGeneration() {
   LOG(isolate_, ResourceEvent("scavenge", "begin"));
 
   // Move pages from new->old generation.
-  PageRange range(new_space()->bottom(), new_space()->top());
+  PageRange range(new_space()->first_allocatable_address(), new_space()->top());
   for (auto it = range.begin(); it != range.end();) {
     Page* p = (*++it)->prev_page();
     new_space()->from_space().RemovePage(p);
@@ -2202,8 +2202,7 @@ void Heap::Scavenge() {
   if (FLAG_concurrent_marking) {
     // Ensure that concurrent marker does not track pages that are
     // going to be unmapped.
-    for (Page* p : PageRange(new_space()->FromSpaceStart(),
-                             new_space()->FromSpaceEnd())) {
+    for (Page* p : PageRange(new_space()->from_space().first_page(), nullptr)) {
       concurrent_marking()->ClearLiveness(p);
     }
   }
@@ -3848,8 +3847,7 @@ void Heap::VerifyCountersBeforeConcurrentSweeping() {
 
 void Heap::ZapFromSpace() {
   if (!new_space_->IsFromSpaceCommitted()) return;
-  for (Page* page :
-       PageRange(new_space_->FromSpaceStart(), new_space_->FromSpaceEnd())) {
+  for (Page* page : PageRange(new_space_->from_space().first_page(), nullptr)) {
     for (Address cursor = page->area_start(), limit = page->area_end();
          cursor < limit; cursor += kPointerSize) {
       Memory::Address_at(cursor) = static_cast<Address>(kFromSpaceZapValue);

src/heap/mark-compact.cc

@@ -128,9 +128,10 @@ void MarkingVerifier::VerifyMarking(NewSpace* space) {
   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.
-  CHECK_EQ(space->bottom(), Page::FromAddress(space->bottom())->area_start());
+  CHECK_EQ(space->first_allocatable_address(),
+           space->first_page()->area_start());
 
-  PageRange range(space->bottom(), end);
+  PageRange range(space->first_allocatable_address(), end);
   for (auto it = range.begin(); it != range.end();) {
     Page* page = *(it++);
     Address limit = it != range.end() ? page->area_end() : end;
@@ -258,7 +259,7 @@ void EvacuationVerifier::VerifyEvacuationOnPage(Address start, Address end) {
 }
 
 void EvacuationVerifier::VerifyEvacuation(NewSpace* space) {
-  PageRange range(space->bottom(), space->top());
+  PageRange range(space->first_allocatable_address(), space->top());
   for (auto it = range.begin(); it != range.end();) {
     Page* page = *(it++);
     Address current = page->area_start();
@@ -488,7 +489,7 @@ void MarkCompactCollector::VerifyMarkbitsAreClean(PagedSpace* space) {
 
 
 void MarkCompactCollector::VerifyMarkbitsAreClean(NewSpace* space) {
-  for (Page* p : PageRange(space->bottom(), space->top())) {
+  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));
   }
@@ -2142,7 +2143,8 @@ void MarkCompactCollector::EvacuatePrologue() {
   // New space.
   NewSpace* new_space = heap()->new_space();
   // Append the list of new space pages to be processed.
-  for (Page* p : PageRange(new_space->bottom(), new_space->top())) {
+  for (Page* p :
+       PageRange(new_space->first_allocatable_address(), new_space->top())) {
     new_space_evacuation_pages_.push_back(p);
   }
   new_space->Flip();
@@ -2954,7 +2956,7 @@ class ArrayBufferTrackerUpdatingItem : public UpdatingItem {
 int MarkCompactCollectorBase::CollectToSpaceUpdatingItems(
     ItemParallelJob* job) {
   // Seed to space pages.
-  const Address space_start = heap()->new_space()->bottom();
+  const Address space_start = heap()->new_space()->first_allocatable_address();
   const Address space_end = heap()->new_space()->top();
   int pages = 0;
   for (Page* page : PageRange(space_start, space_end)) {
@@ -3677,8 +3679,8 @@ void MinorMarkCompactCollector::CollectGarbage() {
 
   {
     TRACE_GC(heap()->tracer(), GCTracer::Scope::MINOR_MC_RESET_LIVENESS);
-    for (Page* p : PageRange(heap()->new_space()->FromSpaceStart(),
-                             heap()->new_space()->FromSpaceEnd())) {
+    for (Page* p :
+         PageRange(heap()->new_space()->from_space().first_page(), nullptr)) {
       DCHECK(!p->IsFlagSet(Page::SWEEP_TO_ITERATE));
       non_atomic_marking_state()->ClearLiveness(p);
       if (FLAG_concurrent_marking) {
@@ -3840,7 +3842,8 @@ void MinorMarkCompactCollector::ClearNonLiveReferences() {
 void MinorMarkCompactCollector::EvacuatePrologue() {
   NewSpace* new_space = heap()->new_space();
   // Append the list of new space pages to be processed.
-  for (Page* p : PageRange(new_space->bottom(), new_space->top())) {
+  for (Page* p :
+       PageRange(new_space->first_allocatable_address(), new_space->top())) {
     new_space_evacuation_pages_.push_back(p);
   }
   new_space->Flip();

src/heap/spaces.cc

@@ -2644,7 +2644,7 @@ void SemiSpace::AssertValidRange(Address start, Address end) {
 // SemiSpaceIterator implementation.
 
 SemiSpaceIterator::SemiSpaceIterator(NewSpace* space) {
-  Initialize(space->bottom(), space->top());
+  Initialize(space->first_allocatable_address(), space->top());
 }
 
 

src/heap/spaces.h

@@ -2383,6 +2383,8 @@ class SemiSpace : public Space {
 
   bool EnsureCurrentCapacity();
 
+  Address space_end() { return memory_chunk_list_.back()->area_end(); }
+
   // Returns the start address of the first page of the space.
   Address space_start() {
     DCHECK_NE(memory_chunk_list_.front(), nullptr);
@@ -2392,9 +2394,6 @@ class SemiSpace : public Space {
   Page* current_page() { return current_page_; }
   int pages_used() { return pages_used_; }
 
-  // Returns one past the end address of the space.
-  Address space_end() { return memory_chunk_list_.back()->area_end(); }
-
   // Returns the start address of the current page of the space.
   Address page_low() { return current_page_->area_start(); }
 
@@ -2455,6 +2454,7 @@ class SemiSpace : public Space {
   }
 
   Page* first_page() { return reinterpret_cast<Page*>(Space::first_page()); }
+  Page* last_page() { return reinterpret_cast<Page*>(Space::last_page()); }
 
   iterator begin() { return iterator(first_page()); }
   iterator end() { return iterator(nullptr); }
@@ -2680,8 +2680,9 @@ class NewSpace : public SpaceWithLinearArea {
   Address original_top() { return original_top_.Value(); }
   Address original_limit() { return original_limit_.Value(); }
 
-  // Return the address of the first object in the active semispace.
-  Address bottom() { return to_space_.space_start(); }
+  // Return the address of the first allocatable address in the active
+  // semispace. This may be the address where the first object resides.
+  Address first_allocatable_address() { return to_space_.space_start(); }
 
   // Get the age mark of the inactive semispace.
   Address age_mark() { return from_space_.age_mark(); }
@@ -2710,18 +2711,6 @@ class NewSpace : public SpaceWithLinearArea {
   // it in steps to guarantee that the observers are notified periodically.
   void UpdateInlineAllocationLimit(size_t size_in_bytes) override;
 
-  // Get the extent of the inactive semispace (for use as a marking stack,
-  // or to zap it). Notice: space-addresses are not necessarily on the
-  // same page, so FromSpaceStart() might be above FromSpaceEnd().
-  Address FromSpacePageLow() { return from_space_.page_low(); }
-  Address FromSpacePageHigh() { return from_space_.page_high(); }
-  Address FromSpaceStart() { return from_space_.space_start(); }
-  Address FromSpaceEnd() { return from_space_.space_end(); }
-
-  // Get the extent of the active semispace's pages' memory.
-  Address ToSpaceStart() { return to_space_.space_start(); }
-  Address ToSpaceEnd() { return to_space_.space_end(); }
-
   inline bool ToSpaceContainsSlow(Address a);
   inline bool FromSpaceContainsSlow(Address a);
   inline bool ToSpaceContains(Object* o);
@@ -2759,6 +2748,9 @@ class NewSpace : public SpaceWithLinearArea {
 
   SemiSpace* active_space() { return &to_space_; }
 
+  Page* first_page() { return to_space_.first_page(); }
+  Page* last_page() { return to_space_.last_page(); }
+
   iterator begin() { return to_space_.begin(); }
   iterator end() { return to_space_.end(); }