Copy ICData descriptors when starting background compilation, so that they do not change while comp…

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 630ffd1ceaede7a6661d47fe4af990282895c967..59fed88a1bd26d99447b19c33047ee68cd5c5f0e 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -7118,6 +7118,33 @@ void Function::RestoreICDataMap(
 }
 
 
+void Function::CopyICDataMap(
+    ZoneGrowableArray<const ICData*>* deopt_id_to_ic_data) const {
+  ASSERT(deopt_id_to_ic_data->is_empty());
+  Zone* zone = Thread::Current()->zone();
+  const Array& saved_ic_data = Array::Handle(zone, ic_data_array());
+  if (saved_ic_data.IsNull()) {
+    return;
+  }
+  const intptr_t saved_length = saved_ic_data.Length();
+  ASSERT(saved_length > 0);
+  if (saved_length > 1) {
+    const intptr_t restored_length = ICData::Cast(Object::Handle(
+        zone, saved_ic_data.At(saved_length - 1))).deopt_id() + 1;
+    deopt_id_to_ic_data->SetLength(restored_length);
+    for (intptr_t i = 0; i < restored_length; i++) {
+      (*deopt_id_to_ic_data)[i] = NULL;
+    }
+    for (intptr_t i = 1; i < saved_length; i++) {
+      ICData& ic_data = ICData::ZoneHandle(zone);
+      ic_data ^= saved_ic_data.At(i);
+      ic_data = ICData::CloneDescriptor(ic_data);
+      (*deopt_id_to_ic_data)[ic_data.deopt_id()] = &ic_data;
+    }
+  }
+}
+
+
 void Function::set_ic_data_array(const Array& value) const {
   StorePointer(&raw_ptr()->ic_data_array_, value.raw());
 }
@@ -12725,6 +12752,23 @@ RawICData* ICData::NewFrom(const ICData& from, intptr_t num_args_tested) {
 }
 
 
+RawICData* ICData::CloneDescriptor(const ICData& from) {
+  Zone* zone = Thread::Current()->zone();
+  const ICData& result = ICData::Handle(ICData::NewDescriptor(
+      zone,
+      Function::Handle(zone, from.owner()),
+      String::Handle(zone, from.target_name()),
+      Array::Handle(zone, from.arguments_descriptor()),
+      from.deopt_id(),
+      from.NumArgsTested()));
+  // Preserve entry array.
+  result.set_ic_data_array(Array::Handle(zone, from.ic_data()));

[siva, 2015/10/27 23:36:45]

The ic_data array doesn't have to be cloned?

[srdjan, 2015/10/28 16:54:43]

No. Added the following comment in .h:

  // Generates a new ICData with descriptor data copied (shallow clone).
  // Entry array of the result is the same as in 'from'. Once entry array is
  // created, it can only change the 'count', all other properties are invariant
  // (target, cids, number of checks).

+  // Copy deoptimization reasons.
+  result.SetDeoptReasons(from.DeoptReasons());
+  return result.raw();
+}
+
+
 void ICData::PrintJSONImpl(JSONStream* stream, bool ref) const {
   JSONObject jsobj(stream);
   AddCommonObjectProperties(&jsobj, "Object", ref);