Collect type feedback for fields.

runtime/vm/code_generator.cc

Index: runtime/vm/code_generator.cc
diff --git a/runtime/vm/code_generator.cc b/runtime/vm/code_generator.cc
index b1f11df6a68f805e53a64c67ffdb625ada54e2ea..2f92c1f73f064ffccc653ad2724c82924dab1b49 100644
--- a/runtime/vm/code_generator.cc
+++ b/runtime/vm/code_generator.cc
@@ -1380,7 +1380,8 @@ DEOPT_REASONS(DEOPT_REASON_ID_TO_TEXT)
 }
 
 
-static void DeoptimizeAt(const Code& optimized_code, uword pc) {
+void DeoptimizeAt(const Code& optimized_code, uword pc) {
+  ASSERT(optimized_code.is_optimized());
   intptr_t deopt_reason = kDeoptUnknown;
   const DeoptInfo& deopt_info =
       DeoptInfo::Handle(optimized_code.GetDeoptInfoAtPc(pc, &deopt_reason));
@@ -1733,4 +1734,17 @@ double DartModulo(double left, double right) {
   return remainder;
 }
 
+
+// Update global type feedback recorded for a field recording the assignment
+// of the given value.
+//   Arg0: Field object;
+//   Arg1: Value that is being stored.
+DEFINE_RUNTIME_ENTRY(UpdateFieldCid, 2) {
+  ASSERT(arguments.ArgCount() == kUpdateFieldCidRuntimeEntry.argument_count());
+  const Field& field = Field::CheckedHandle(arguments.ArgAt(0));
+  const Object& value = Object::Handle(arguments.ArgAt(1));
+
+  field.UpdateCid(Class::Handle(value.clazz()).id());

[Ivan Posva, 2013/03/19 04:42:05]

Do you think it would be useful to have an ClassId() accessor on the Object
handle?

Then we would be able to write:
field.UpdateCid(value.ClassId());
instead of loading the class from the value and reading the id.

[Vyacheslav Egorov (Google), 2013/03/19 06:58:59]

It can be useful but I would leave it out of scope for this change. This is slow
path anyways.

[Ivan Posva, 2013/03/19 15:48:51]

I did not mean to imply to have this in this CL. I was just wondering whether it
would be helpful as I see the class id accessed at several places, either going
through the class as here or by exploding the friends of class RawObject.

+}
+
 }  // namespace dart