Revert "[heap] Allow LocalHeap on the main thread"

This reverts commit bebb2bdc.

Reason for revert: Breaks GarbageCollectionWithLocalHeap test.
https://ci.chromium.org/p/v8/builders/ci/V8%20Linux%20-%20debug/31107

Original change's description:
> [heap] Allow LocalHeap on the main thread
> 
> This changes the safepoint scope to skip LocalHeap that is active
> for the current thread to avoid deadlocking.
> 
> Bug: v8:10315
> Change-Id: I45e80ae66d0dbbe768107aa9cf0603204c644d9f
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2289983
> Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
> Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#68769}

TBR=ulan@chromium.org,dinfuehr@chromium.org

Change-Id: Ifba8218f9104afed3f2d92258296067f8f424062
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:10315
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2290573Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68770}

src/heap/safepoint.cc

@@ -23,25 +23,17 @@ void GlobalSafepoint::EnterSafepointScope() {
   if (!FLAG_local_heaps) return;
 
   if (++active_safepoint_scopes_ > 1) return;
-
   local_heaps_mutex_.Lock();
-  local_heap_of_this_thread_ = LocalHeap::Current();
 
   barrier_.Arm();
 
   for (LocalHeap* current = local_heaps_head_; current;
        current = current->next_) {
-    if (current == local_heap_of_this_thread_) {
-      continue;
-    }
     current->RequestSafepoint();
   }
 
   for (LocalHeap* current = local_heaps_head_; current;
        current = current->next_) {
-    if (current == local_heap_of_this_thread_) {
-      continue;
-    }
     current->state_mutex_.Lock();
 
     while (current->state_ == LocalHeap::ThreadState::Running) {
@@ -56,19 +48,13 @@ void GlobalSafepoint::LeaveSafepointScope() {
   DCHECK_GT(active_safepoint_scopes_, 0);
   if (--active_safepoint_scopes_ > 0) return;
 
-  DCHECK_EQ(local_heap_of_this_thread_, LocalHeap::Current());
-
   for (LocalHeap* current = local_heaps_head_; current;
        current = current->next_) {
-    if (current == local_heap_of_this_thread_) {
-      continue;
-    }
     current->state_mutex_.Unlock();
   }
 
   barrier_.Disarm();
 
-  local_heap_of_this_thread_ = nullptr;
   local_heaps_mutex_.Unlock();
 }
 

src/heap/safepoint.h

@@ -77,8 +77,6 @@ class GlobalSafepoint {
 
   int active_safepoint_scopes_;
 
-  LocalHeap* local_heap_of_this_thread_;
-
   friend class SafepointScope;
   friend class LocalHeap;
   friend class PersistentHandles;

test/cctest/heap/test-heap.cc

@@ -7141,22 +7141,6 @@ HEAP_TEST(GCDuringOffThreadMergeWithTransferHandle) {
   CHECK_EQ(transfer_handle.ToHandle()->length(), 10);
 }
 
-TEST(GarbageCollectionWithLocalHeap) {
-  FLAG_local_heaps = true;
-  ManualGCScope manual_gc_scope;
-  CcTest::InitializeVM();
-
-  Heap* heap = CcTest::i_isolate()->heap();
-
-  LocalHeap local_heap(heap);
-  CcTest::CollectGarbage(OLD_SPACE);
-  {
-    ParkedScope parked_scope(&local_heap);
-    CcTest::CollectGarbage(OLD_SPACE);
-  }
-  CcTest::CollectGarbage(OLD_SPACE);
-}
-
 }  // namespace heap
 }  // namespace internal
 }  // namespace v8

test/unittests/heap/safepoint-unittest.cc

@@ -138,24 +138,5 @@ TEST_F(SafepointTest, StopRunningThreads) {
   CHECK_EQ(safepoint_count, kRuns * kSafepoints);
 }
 
-TEST_F(SafepointTest, SkipLocalHeapOfThisThread) {
-  Heap* heap = i_isolate()->heap();
-  FLAG_local_heaps = true;
-  LocalHeap local_heap(heap);
-  {
-    SafepointScope scope(heap);
-    local_heap.Safepoint();
-  }
-  {
-    ParkedScope parked_scope(&local_heap);
-    SafepointScope scope(heap);
-    local_heap.Safepoint();
-  }
-  {
-    SafepointScope scope(heap);
-    local_heap.Safepoint();
-  }
-}
-
 }  // namespace internal
 }  // namespace v8