Track loading happening in parallel with background compilation and abort compilation if necessary.

runtime/vm/isolate.h

Index: runtime/vm/isolate.h
diff --git a/runtime/vm/isolate.h b/runtime/vm/isolate.h
index 8d2508fbd9461f131fad072bc8bd4f1390a5f9a8..350e39016819fa2a318d10fb4c19460e5cff9faa 100644
--- a/runtime/vm/isolate.h
+++ b/runtime/vm/isolate.h
@@ -487,30 +487,40 @@ class Isolate : public BaseIsolate {
     all_classes_finalized_ = value;
   }
 
-  static const uint32_t kInvalidGen = 0;
+  // True during top level parsing.
+  bool IsTopLevelParsing() {
+    const intptr_t value =
+        AtomicOperations::LoadRelaxedIntPtr(&top_level_parsing_count_);
+    ASSERT(value >= 0);
+    return value > 0;
+  }
 
-  void IncrCHAInvalidationGen() {
-    cha_invalidation_gen_++;
-    if (cha_invalidation_gen_ == kInvalidGen) cha_invalidation_gen_++;
+  void IncrTopLevelParsingCount() {
+    AtomicOperations::IncrementBy(&top_level_parsing_count_, 1);
+  }
+  void DecrTopLevelParsingCount() {
+    AtomicOperations::DecrementBy(&top_level_parsing_count_, 1);
   }
-  void ResetCHAInvalidationGen() { cha_invalidation_gen_ = kInvalidGen; }
-  uint32_t cha_invalidation_gen() const { return cha_invalidation_gen_; }
 
+  static const uint32_t kInvalidGen = 0;
 
   void IncrFieldInvalidationGen() {
-    field_invalidation_gen_++;
-    if (field_invalidation_gen_ == kInvalidGen) field_invalidation_gen_++;
+    AtomicOperations::IncrementBy(&field_invalidation_gen_, 1);
+    if (field_invalidation_gen_ == kInvalidGen) {
+      AtomicOperations::IncrementBy(&field_invalidation_gen_, 1);
+    }
   }
+  intptr_t field_invalidation_gen() const { return field_invalidation_gen_; }
 
-  void ResetFieldInvalidationGen() { field_invalidation_gen_ = kInvalidGen; }
-  uint32_t field_invalidation_gen() const { return field_invalidation_gen_; }
-
-  void IncrPrefixInvalidationGen() {
-    prefix_invalidation_gen_++;
-    if (prefix_invalidation_gen_ == kInvalidGen) prefix_invalidation_gen_++;
+  void IncrLoadingInvalidationGen() {
+    AtomicOperations::IncrementBy(&loading_invalidation_gen_, 1);
+    if (loading_invalidation_gen_ == kInvalidGen) {
+      AtomicOperations::IncrementBy(&loading_invalidation_gen_, 1);
+    }
+  }
+  intptr_t loading_invalidation_gen() {
+    return AtomicOperations::LoadRelaxedIntPtr(&loading_invalidation_gen_);
   }
-  void ResetPrefixInvalidationGen() { prefix_invalidation_gen_ = kInvalidGen; }
-  uint32_t prefix_invalidation_gen() const { return prefix_invalidation_gen_; }
 
   // Used by background compiler which field became boxed and must trigger
   // deoptimization in the mutator thread.
@@ -730,9 +740,9 @@ class Isolate : public BaseIsolate {
   // Invalidation generations; used to track events occuring in parallel
   // to background compilation. The counters may overflow, which is OK
   // since we check for equality to detect if an event occured.
-  uint32_t cha_invalidation_gen_;
-  uint32_t field_invalidation_gen_;
-  uint32_t prefix_invalidation_gen_;
+  intptr_t field_invalidation_gen_;
+  intptr_t loading_invalidation_gen_;
+  intptr_t top_level_parsing_count_;
 
   // Protect access to boxed_field_list_.
   Mutex* boxed_field_list_mutex_;