Deoptimization can occur at Dart calls (includes native calls to C) but not at runtime calls. This …

runtime/vm/code_descriptors.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/code_descriptors.h"
 
+#include "vm/code_generator.h"
+
 namespace dart {
 
 void DescriptorList::AddDescriptor(PcDescriptors::Kind kind,
                                    intptr_t pc_offset,
                                    intptr_t deopt_id,
                                    intptr_t token_index,
                                    intptr_t try_index) {
   struct PcDesc data;
   data.pc_offset = pc_offset;
   data.kind = kind;
   data.deopt_id = deopt_id;
   data.token_index = token_index;
   data.try_index = try_index;
   list_.Add(data);
 }
 
 
-void DescriptorList::AddDeoptInfo(intptr_t pc_offset,
-                                  intptr_t deopt_id,
-                                  intptr_t token_index,
-                                  intptr_t deopt_array_index) {
+void DescriptorList::AddDeoptIndex(intptr_t pc_offset,
+                                   intptr_t deopt_id,
+                                   intptr_t deopt_reason,
+                                   intptr_t deopt_array_index) {
   struct PcDesc data;
   data.pc_offset = pc_offset;
   data.kind = PcDescriptors::kDeoptIndex;
   data.deopt_id = deopt_id;
-  data.token_index = token_index;
+  // Token index is used for deopt reason.
+  ASSERT((kDeoptUnknown <= deopt_reason) && (deopt_reason < kDeoptNumReasons));
+  data.token_index = deopt_reason;

[siva, 2012/08/30 01:37:30]

overloading token_index field as deopt_reason can be a bit confusing when
reading code.

I am wondering if it would make the code more readable if we called the field
data and added accessor functions
SetTokenIndex(intptr_t value);
intptr_t TokenIndex();
SetDeoptReason(intptr_t value);
intptr_t DeoptReason();

and used these accessor functions.

[srdjan, 2012/08/30 17:16:16]

Done.

   // Try_index is reused for deopt_array_index.
   data.try_index = deopt_array_index;
   list_.Add(data);
 }
 
 
 RawPcDescriptors* DescriptorList::FinalizePcDescriptors(uword entry_point) {
   intptr_t num_descriptors = Length();
   const PcDescriptors& descriptors =
       PcDescriptors::Handle(PcDescriptors::New(num_descriptors));
@@ skipping 48 matching lines @@
 }
 
 
 RawStackmap* StackmapTableBuilder::MapAt(int index) const {
   Stackmap& map = Stackmap::Handle();
   map ^= list_.At(index);
   return map.raw();
 }
 
 }  // namespace dart