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;
+    }
+  }
+}

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

This function seems identical to RestoreICDataMap except for the CloneDescriptor
part.

Can we just call RestoreICDataMap in both cases (IsMutatorThread and
!IsMutatorThread) and then in the case of !IsMutatorThread we could do a loop to
clone the descriptors ?

Or we could add a 'clone_descriptor' parameter to RestoreICDataMap and call it
accordingly.

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

Yes, passing argument clone_descriptor.
Also added (as discussed offline) Compiler::IsBackgroundCompilation().

+
+
 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()));
+  // 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);