Add more safe points in compiler

runtime/vm/pages.cc

Index: runtime/vm/pages.cc
diff --git a/runtime/vm/pages.cc b/runtime/vm/pages.cc
index 9768bc5f2510fad9045046e9a9564144c5968753..ce8bf42aad31e8753f932ecd339d16d25e061af0 100644
--- a/runtime/vm/pages.cc
+++ b/runtime/vm/pages.cc
@@ -849,6 +849,8 @@ void PageSpace::MarkSweep(bool invoke_api_callbacks) {
   Isolate* isolate = heap_->isolate();
   ASSERT(isolate == Isolate::Current());
 
+  const int64_t pre_wait_for_sweepers = OS::GetCurrentMonotonicMicros();
+
   // Wait for pending tasks to complete and then account for the driver task.
   {
     MonitorLocker locker(tasks_lock());
@@ -857,6 +859,9 @@ void PageSpace::MarkSweep(bool invoke_api_callbacks) {
     }
     set_tasks(1);
   }
+
+  const int64_t pre_safe_point = OS::GetCurrentMonotonicMicros();
+
   // Ensure that all threads for this isolate are at a safepoint (either
   // stopped or in native code). We have guards around Newgen GC and oldgen GC
   // to ensure that if two threads are racing to collect at the same time the
@@ -864,6 +869,8 @@ void PageSpace::MarkSweep(bool invoke_api_callbacks) {
   {
     SafepointOperationScope safepoint_scope(thread);
 
+    const int64_t start = OS::GetCurrentMonotonicMicros();
+
     // Perform various cleanup that relies on no tasks interfering.
     isolate->class_table()->FreeOldTables();
 
@@ -882,8 +889,6 @@ void PageSpace::MarkSweep(bool invoke_api_callbacks) {
       OS::PrintErr(" done.\n");
     }
 
-    const int64_t start = OS::GetCurrentMonotonicMicros();
-
     // Make code pages writable.
     WriteProtectCode(false);
 
@@ -991,6 +996,8 @@ void PageSpace::MarkSweep(bool invoke_api_callbacks) {
     page_space_controller_.EvaluateGarbageCollection(
         usage_before, GetCurrentUsage(), start, end);
 
+    heap_->RecordTime(kConcurrentSweep, pre_safe_point - pre_wait_for_sweepers);
+    heap_->RecordTime(kSafePoint, start - pre_safe_point);
     heap_->RecordTime(kMarkObjects, mid1 - start);
     heap_->RecordTime(kResetFreeLists, mid2 - mid1);
     heap_->RecordTime(kSweepPages, mid3 - mid2);