[heap] Handle paged spaces in Heap::MakeHeapIterable

Complete implementation of Heap::MakeHeapIterable() by also making the
LABs of paged spaces iterable. This method is the one to use when
the heap and/or a particular space shall be iterable.

Bug: v8:12338
Change-Id: Id859cf1a05df21a54939c504c59d7b1ccd659c9b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3277888
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77891}

src/heap/heap.cc

@@ -3522,13 +3522,18 @@ void Heap::CreateFillerForArray(T object, int elements_to_trim,
 void Heap::MakeHeapIterable() {
   mark_compact_collector()->EnsureSweepingCompleted();
 
-  MakeLocalHeapLabsIterable();
-}
-
-void Heap::MakeLocalHeapLabsIterable() {
   safepoint()->IterateLocalHeaps([](LocalHeap* local_heap) {
     local_heap->MakeLinearAllocationAreaIterable();
   });
+
+  PagedSpaceIterator spaces(this);
+  for (PagedSpace* space = spaces.Next(); space != nullptr;
+       space = spaces.Next()) {
+    space->MakeLinearAllocationAreaIterable();
+  }
+
+  // New space is bump-pointer allocation only and therefore guaranteed to be
+  // iterable up to top().
 }
 
 namespace {
@@ -4598,8 +4603,6 @@ void Heap::VerifyRememberedSetFor(HeapObject object) {
 
 #ifdef DEBUG
 void Heap::VerifyCountersAfterSweeping() {
-  MakeLocalHeapLabsIterable();
-
   PagedSpaceIterator spaces(this);
   for (PagedSpace* space = spaces.Next(); space != nullptr;
        space = spaces.Next()) {

src/heap/heap.h

@@ -1652,6 +1652,10 @@ class Heap {
 
   void UpdateEpochFull();
 
+  // Ensure that we have swept all spaces in such a way that we can iterate
+  // over all objects.
+  void MakeHeapIterable();
+
  private:
   using ExternalStringTableUpdaterCallback = String (*)(Heap* heap,
                                                         FullObjectSlot pointer);
@@ -1781,13 +1785,6 @@ class Heap {
   // with the allocation memento of the object at the top
   void EnsureFillerObjectAtTop();
 
-  // Ensure that we have swept all spaces in such a way that we can iterate
-  // over all objects.  May cause a GC.
-  void MakeHeapIterable();
-
-  // Ensure that LABs of local heaps are iterable.
-  void MakeLocalHeapLabsIterable();
-
   // Performs garbage collection in a safepoint.
   // Returns the number of freed global handles.
   size_t PerformGarbageCollection(

src/heap/paged-spaces.cc

@@ -37,8 +37,8 @@ PagedSpaceObjectIterator::PagedSpaceObjectIterator(Heap* heap,
       cage_base_(heap->isolate())
 #endif  // V8_COMPRESS_POINTERS
 {
-  space_->MakeLinearAllocationAreaIterable();
+  heap->MakeHeapIterable();
-  heap->mark_compact_collector()->EnsureSweepingCompleted();
+  USE(space_);
 }
 
 PagedSpaceObjectIterator::PagedSpaceObjectIterator(Heap* heap,
@@ -54,8 +54,7 @@ PagedSpaceObjectIterator::PagedSpaceObjectIterator(Heap* heap,
       cage_base_(heap->isolate())
 #endif  // V8_COMPRESS_POINTERS
 {
-  space_->MakeLinearAllocationAreaIterable();
+  heap->MakeHeapIterable();
-  heap->mark_compact_collector()->EnsureSweepingCompleted();
 #ifdef DEBUG
   AllocationSpace owner = page->owner_identity();
   DCHECK(owner == OLD_SPACE || owner == MAP_SPACE || owner == CODE_SPACE);

test/mkgrokdump/mkgrokdump.cc

@@ -12,6 +12,7 @@
 #include "src/heap/heap-inl.h"
 #include "src/heap/paged-spaces-inl.h"
 #include "src/heap/read-only-heap.h"
+#include "src/heap/safepoint.h"
 #include "src/heap/spaces.h"
 #include "src/objects/objects-inl.h"
 
@@ -128,6 +129,7 @@ static int DumpHeapConstants(FILE* out, const char* argv0) {
   {
     Isolate::Scope scope(isolate);
     i::Heap* heap = reinterpret_cast<i::Isolate*>(isolate)->heap();
+    i::SafepointScope safepoint_scope(heap);
     i::ReadOnlyHeap* read_only_heap =
         reinterpret_cast<i::Isolate*>(isolate)->read_only_heap();
     i::PrintF(out, "%s", kHeader);