[heap] Increase gc_count_ in safepoint

Incrementing gc_count_ races with
Heap::IncrementalMarkingLimitReached(), which starts incremental marking
immediately on every second GC.

Bug: v8:10315
Change-Id: Ieb1126bb4ecc472afe5fdd023a601d753576752e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2346648Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69320}

src/heap/heap.cc

@@ -423,7 +423,7 @@ GarbageCollector Heap::SelectGarbageCollector(AllocationSpace space,
     return MARK_COMPACTOR;
   }
 
-  if (FLAG_gc_global || (FLAG_stress_compaction && (gc_count_ & 1) != 0)) {
+  if (FLAG_gc_global || ShouldStressCompaction()) {
     *reason = "GC in old space forced by flags";
     return MARK_COMPACTOR;
   }
@@ -817,10 +817,6 @@ bool Heap::UncommitFromSpace() { return new_space_->UncommitFromSpace(); }
 
 void Heap::GarbageCollectionPrologue() {
   TRACE_GC(tracer(), GCTracer::Scope::HEAP_PROLOGUE);
-  {
-    AllowHeapAllocation for_the_first_part_of_prologue;
-    gc_count_++;
-  }
 
   // Reset GC statistics.
   promoted_objects_size_ = 0;
@@ -852,6 +848,8 @@ void Heap::GarbageCollectionPrologue() {
 }
 
 void Heap::GarbageCollectionPrologueInSafepoint() {
+  gc_count_++;
+
   UpdateNewSpaceAllocationCounter();
   CheckNewSpaceExpansionCriteria();
 }
@@ -5042,8 +5040,7 @@ Heap::IncrementalMarkingLimit Heap::IncrementalMarkingLimitReached() {
     // Incremental marking is disabled or it is too early to start.
     return IncrementalMarkingLimit::kNoLimit;
   }
-  if ((FLAG_stress_compaction && (gc_count_ & 1) != 0) ||
-      HighMemoryPressure()) {
+  if (ShouldStressCompaction() || HighMemoryPressure()) {
     // If there is high memory pressure or stress testing is enabled, then
     // start marking immediately.
     return IncrementalMarkingLimit::kHardLimit;
@@ -5110,6 +5107,10 @@ Heap::IncrementalMarkingLimit Heap::IncrementalMarkingLimitReached() {
   return IncrementalMarkingLimit::kSoftLimit;
 }
 
+bool Heap::ShouldStressCompaction() const {
+  return FLAG_stress_compaction && (gc_count_ & 1) != 0;
+}
+
 void Heap::EnableInlineAllocation() {
   if (!inline_allocation_disabled_) return;
   inline_allocation_disabled_ = false;

src/heap/heap.h

@@ -1867,6 +1867,8 @@ class Heap {
   enum class IncrementalMarkingLimit { kNoLimit, kSoftLimit, kHardLimit };
   IncrementalMarkingLimit IncrementalMarkingLimitReached();
 
+  bool ShouldStressCompaction() const;
+
   bool UseGlobalMemoryScheduling() const {
     return FLAG_global_gc_scheduling && local_embedder_heap_tracer();
   }