[heap] Revise page iterations

mark-compact.cc: Iterate over all new space pages.
heap-layout-tracer.cc: Iterate over the paged new space.

Bug: v8:12612
Change-Id: I4d8dfc48632908a80793a77c211020452c675ecf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3823134Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82365}

src/heap/heap-layout-tracer.cc

@@ -50,16 +50,22 @@ void HeapLayoutTracer::PrintBasicMemoryChunk(std::ostream& os,
 
 // static
 void HeapLayoutTracer::PrintHeapLayout(std::ostream& os, Heap* heap) {
-  const SemiSpaceNewSpace* semi_space_new_space =
-      SemiSpaceNewSpace::From(heap->new_space());
-  for (ConstPageIterator it = semi_space_new_space->to_space().begin();
-       it != semi_space_new_space->to_space().end(); ++it) {
-    PrintBasicMemoryChunk(os, **it, "to_space");
-  }
+  if (FLAG_minor_mc) {
+    const PagedNewSpace* paged_new_space =
+        PagedNewSpace::From(heap->new_space());
+    for (const Page* page : *paged_new_space) {
+      PrintBasicMemoryChunk(os, *page, "new_space");
+    }
+  } else {
+    const SemiSpaceNewSpace* semi_space_new_space =
+        SemiSpaceNewSpace::From(heap->new_space());
+    for (const Page* page : semi_space_new_space->to_space()) {
+      PrintBasicMemoryChunk(os, *page, "to_space");
+    }
 
-  for (ConstPageIterator it = semi_space_new_space->from_space().begin();
-       it != semi_space_new_space->from_space().end(); ++it) {
-    PrintBasicMemoryChunk(os, **it, "from_space");
+    for (const Page* page : semi_space_new_space->from_space()) {
+      PrintBasicMemoryChunk(os, *page, "from_space");
+    }
   }
 
   OldGenerationMemoryChunkIterator it(heap);

src/heap/mark-compact.cc

@@ -3843,13 +3843,12 @@ void MarkCompactCollector::EvacuatePrologue() {
 
   if (new_space) {
     // Append the list of new space pages to be processed.
-    for (Page* p :
-         PageRange(new_space->first_allocatable_address(), new_space->top())) {
-      new_space_evacuation_pages_.push_back(p);
+    for (Page* p : *new_space) {
+      if (non_atomic_marking_state()->live_bytes(p) > 0) {
+        new_space_evacuation_pages_.push_back(p);
+      }
     }
     new_space->EvacuatePrologue();
-
-    DCHECK_EQ(new_space->Size(), 0);
   }
 
   if (heap()->new_lo_space()) {
@@ -5834,9 +5833,11 @@ 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->first_allocatable_address(), new_space->top())) {
-    new_space_evacuation_pages_.push_back(p);
+  DCHECK_NOT_NULL(new_space);
+  for (Page* p : *new_space) {
+    if (non_atomic_marking_state()->live_bytes(p) > 0) {
+      new_space_evacuation_pages_.push_back(p);
+    }
   }
 
   new_space->EvacuatePrologue();
@@ -6343,7 +6344,7 @@ void MinorMarkCompactCollector::EvacuatePagesInParallel() {
 
   for (Page* page : new_space_evacuation_pages_) {
     intptr_t live_bytes_on_page = non_atomic_marking_state()->live_bytes(page);
-    if (live_bytes_on_page == 0) continue;
+    DCHECK_LT(0, live_bytes_on_page);
     live_bytes += live_bytes_on_page;
     if (ShouldMovePage(page, live_bytes_on_page, AlwaysPromoteYoung::kNo)) {
       if (page->IsFlagSet(MemoryChunk::NEW_SPACE_BELOW_AGE_MARK)) {