Another fix for debugging stack traces and captured variables.

runtime/vm/debugger.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/debugger.h"
 
 #include "include/dart_api.h"
 
 #include "vm/code_generator.h"
 #include "vm/code_patcher.h"
@@ skipping 321 matching lines @@
           context_level_ = var_info.index;
         }
       }
     }
     ASSERT(context_level_ >= 0);
   }
   return context_level_;
 }
 
 
-RawContext* ActivationFrame::GetSavedContext(const Context& ctx) {
+// Get the caller's context, or return ctx if the function does not
+// save the caller's context on entry.
+RawContext* ActivationFrame::GetSavedCallerContext(const Context& ctx) {
   GetVarDescriptors();
   intptr_t var_desc_len = var_descriptors_.Length();
   for (int i = 0; i < var_desc_len; i++) {
     RawLocalVarDescriptors::VarInfo var_info;
     var_descriptors_.GetInfo(i, &var_info);
-    if (var_info.kind == RawLocalVarDescriptors::kContextChain) {
+    if (var_info.kind == RawLocalVarDescriptors::kSavedCallerContext) {
       return reinterpret_cast<RawContext*>(GetLocalVarValue(var_info.index));
     }
   }
   return ctx.raw();
 }
 
 
+// Get the saved context if the callee of this activation frame is a
+// closure function.
+RawContext* ActivationFrame::GetSavedCurrentContext() {
+  GetVarDescriptors();
+  intptr_t var_desc_len = var_descriptors_.Length();
+  for (int i = 0; i < var_desc_len; i++) {
+    RawLocalVarDescriptors::VarInfo var_info;
+    var_descriptors_.GetInfo(i, &var_info);
+    if (var_info.kind == RawLocalVarDescriptors::kSavedCurrentContext) {
+      return reinterpret_cast<RawContext*>(GetLocalVarValue(var_info.index));
+    }
+  }
+  UNREACHABLE();
+  return Context::null();
+}
+
+
 ActivationFrame* DebuggerStackTrace::GetHandlerFrame(
     const Instance& exc_obj) const {
   ExceptionHandlers& handlers = ExceptionHandlers::Handle();
   Array& handled_types = Array::Handle();
   AbstractType& type = Type::Handle();
   const TypeArguments& no_instantiator = TypeArguments::Handle();
   for (int frame_index = 0; frame_index < Length(); frame_index++) {
     ActivationFrame* frame = trace_[frame_index];
     intptr_t try_index = frame->TryIndex();
     if (try_index < 0) continue;
@@ skipping 518 matching lines @@
   StackFrame* frame = iterator.NextFrame();
   bool optimized_frame_found = false;
   while (frame != NULL) {
     ASSERT(frame->IsValid());
     if (frame->IsDartFrame()) {
       code = frame->LookupDartCode();
       ActivationFrame* activation = new ActivationFrame(frame->pc(),
                                                         frame->fp(),
                                                         frame->sp(),
                                                         code);
+      // If this activation frame called a closure, the function has
+      // saved its context before the call.
+      if (stack_trace->Length() > 0) {
+        ActivationFrame* callee_frame =
+            stack_trace->ActivationFrameAt(stack_trace->Length() - 1);
+        if (callee_frame->function().IsClosureFunction()) {
+          ctx = activation->GetSavedCurrentContext();
+        }
+      }
       if (optimized_frame_found || code.is_optimized()) {
         // Set context to null, to avoid returning bad context variable values.
         activation->SetContext(Context::Handle());
         optimized_frame_found = true;
       } else {
         activation->SetContext(ctx);
-        ctx = activation->GetSavedContext(ctx);
       }
       stack_trace->AddActivation(activation);
+      // Get caller's context if this function saved it on entry.
+      ctx = activation->GetSavedCallerContext(ctx);
     } else if (frame->IsEntryFrame()) {
       ctx = reinterpret_cast<EntryFrame*>(frame)->SavedContext();
     }
     frame = iterator.NextFrame();
   }
   return stack_trace;
 }
 
 
 void Debugger::SetExceptionPauseInfo(Dart_ExceptionPauseInfo pause_info) {
@@ skipping 826 matching lines @@
 }
 
 
 void Debugger::RegisterCodeBreakpoint(CodeBreakpoint* bpt) {
   ASSERT(bpt->next() == NULL);
   bpt->set_next(code_breakpoints_);
   code_breakpoints_ = bpt;
 }
 
 }  // namespace dart