VM: Enable collection of unoptimized code for optimized functions.

runtime/vm/raw_object.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/raw_object.h"
 
 #include "vm/class_table.h"
 #include "vm/dart.h"
 #include "vm/freelist.h"
 #include "vm/isolate.h"
@@ skipping 395 matching lines @@
 }
 
 
 intptr_t RawRedirectionData::VisitRedirectionDataPointers(
     RawRedirectionData* raw_obj, ObjectPointerVisitor* visitor) {
   visitor->VisitPointers(raw_obj->from(), raw_obj->to());
   return RedirectionData::InstanceSize();
 }
 
 
-bool RawFunction::SkipCode(RawFunction* raw_fun) {
+bool RawFunction::SkipCode(RawFunction* raw_fun, bool visit_current_code) {

[Vyacheslav Egorov (Google), 2015/04/09 12:23:08]

The name is *very* confusing. Rename it do something like CheckUsageCounter or
DecayUsageCounter.

[Florian Schneider, 2015/04/09 14:48:38]

Done.

   // NOTE: This code runs while GC is in progress and runs within
   // a NoHandleScope block. Hence it is not okay to use regular Zone or
   // Scope handles. We use direct stack handles, and so the raw pointers in
   // these handles are not traversed. The use of handles is mainly to
   // be able to reuse the handle based code and avoid having to add
   // helper functions to the raw object interface.
   Function fn;
   fn = raw_fun;
 
   Code code;
-  code = fn.CurrentCode();
+  if (visit_current_code) {
+    code = fn.CurrentCode();
+  } else {
+    code = fn.unoptimized_code();
+  }
 
   if (fn.HasCode() &&  // The function may not have code.
       !fn.is_intrinsic() &&  // These may not increment the usage counter.
-      !code.is_optimized() &&
-      (fn.CurrentCode() == fn.unoptimized_code()) &&
+      (!visit_current_code || !code.is_optimized()) &&
       !code.HasBreakpoint() &&
       (fn.usage_counter() >= 0)) {
     fn.set_usage_counter(fn.usage_counter() / 2);
     if (FLAG_always_drop_code || (fn.usage_counter() == 0)) {

[Vyacheslav Egorov (Google), 2015/04/09 12:23:08]

return (FLAG_always_drop_code || ...);

[Florian Schneider, 2015/04/09 14:48:38]

Done.

       return true;
     }
   }
   return false;
 }
 
 
 intptr_t RawFunction::VisitFunctionPointers(RawFunction* raw_obj,
                                             ObjectPointerVisitor* visitor) {
-  if (visitor->visit_function_code() ||
-      !RawFunction::SkipCode(raw_obj)) {
-    visitor->VisitPointers(raw_obj->from(), raw_obj->to());
+  visitor->VisitPointers(raw_obj->from(), raw_obj->to_no_code());
+  if (visitor->visit_function_code() || !SkipCode(raw_obj, true)) {

[Vyacheslav Egorov (Google), 2015/04/09 12:23:08]

I think bool parameter is a bit confusing. Maybe pass RawCode down? We are in
the middle of GC anyways.

[Florian Schneider, 2015/04/09 14:48:38]

Done.

+    visitor->VisitPointer(
+        reinterpret_cast<RawObject**>(&raw_obj->ptr()->instructions_));
   } else {
-    GrowableArray<RawFunction*>* sfga = visitor->skipped_code_functions();
-    ASSERT(sfga != NULL);
-    sfga->Add(raw_obj);
-    visitor->VisitPointers(raw_obj->from(), raw_obj->to_no_code());
+    visitor->skipped_current_code_functions()->Add(raw_obj);
+  }
+
+  if (visitor->visit_function_code() || !SkipCode(raw_obj, false)) {

[Vyacheslav Egorov (Google), 2015/04/09 12:23:08]

we decay fn.usage_counter() twice. I think it should be decayed only once per
VisitFunctionPointers invocation.

[Florian Schneider, 2015/04/09 14:48:38]

Done.

+    visitor->VisitPointer(
+        reinterpret_cast<RawObject**>(&raw_obj->ptr()->unoptimized_code_));
+  } else {
+    visitor->skipped_unoptimized_code_functions()->Add(raw_obj);
   }
   return Function::InstanceSize();
 }
 
 
 intptr_t RawField::VisitFieldPointers(RawField* raw_obj,
                                       ObjectPointerVisitor* visitor) {
   visitor->VisitPointers(raw_obj->from(), raw_obj->to());
   return Field::InstanceSize();
 }
@@ skipping 467 matching lines @@
 intptr_t RawUserTag::VisitUserTagPointers(
     RawUserTag* raw_obj, ObjectPointerVisitor* visitor) {
   // Make sure that we got here with the tagged pointer as this.
   ASSERT(raw_obj->IsHeapObject());
   visitor->VisitPointers(raw_obj->from(), raw_obj->to());
   return UserTag::InstanceSize();
 }
 
 
 }  // namespace dart