Disable stack context when its frame is for optimized code.

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 286 matching lines @@
 void ActivationFrame::GetVarDescriptors() {
   if (var_descriptors_.IsNull()) {
     var_descriptors_ = code().var_descriptors();
     ASSERT(!var_descriptors_.IsNull());
   }
 }
 
 
 // Calculate the context level at the current token index of the frame.
 intptr_t ActivationFrame::ContextLevel() {
-  if (context_level_ < 0) {
+  if (context_level_ < 0 && !ctx_.IsNull()) {
+    ASSERT(!code_.is_optimized());
     context_level_ = 0;
     intptr_t pc_desc_idx = PcDescIndex();
     ASSERT(!pc_desc_.IsNull());
     if (pc_desc_.DescriptorKind(pc_desc_idx) == PcDescriptors::kReturn) {
       // Special case: the context chain has already been deallocated.
       // The context level is 0.
       return context_level_;
     }
     intptr_t innermost_begin_pos = 0;
     intptr_t activation_token_pos = TokenPos();
@@ skipping 168 matching lines @@
   RawLocalVarDescriptors::VarInfo var_info;
   var_descriptors_.GetInfo(desc_index, &var_info);
   ASSERT(token_pos != NULL);
   *token_pos = var_info.begin_pos;
   ASSERT(end_pos != NULL);
   *end_pos = var_info.end_pos;
   ASSERT(value != NULL);
   if (var_info.kind == RawLocalVarDescriptors::kStackVar) {
     *value = GetLocalVarValue(var_info.index);
   } else {
-    // TODO(tball): enable context variables once problem with VariableAt() is
-    // fixed, where frame_ctx_level is sometimes off by 1 (issues 8593 and 8594)
-    /*
     ASSERT(var_info.kind == RawLocalVarDescriptors::kContextVar);
-    ASSERT(!ctx_.IsNull());
     // The context level at the PC/token index of this activation frame.
     intptr_t frame_ctx_level = ContextLevel();
+    if (ctx_.IsNull()) {
+      *value = Symbols::New("<unknown>");
+      return;
+    }
     // The context level of the variable.
     intptr_t var_ctx_level = var_info.scope_id;
     intptr_t level_diff = frame_ctx_level - var_ctx_level;
     intptr_t ctx_slot = var_info.index;
     if (level_diff == 0) {
       *value = ctx_.At(ctx_slot);
     } else {
       ASSERT(level_diff > 0);
       Context& ctx = Context::Handle(ctx_.raw());
       while (level_diff > 0) {
         ASSERT(!ctx.IsNull());
         level_diff--;
         ctx = ctx.parent();
       }
       ASSERT(!ctx.IsNull());
       *value = ctx.At(ctx_slot);
-    } */
-    *value = Symbols::New("<unknown>");
+    }
   }
 }
 
 
 RawArray* ActivationFrame::GetLocalVariables() {
   GetDescIndices();
   intptr_t num_variables = desc_indices_.length();
   String& var_name = String::Handle();
   Instance& value = Instance::Handle();
   const Array& list = Array::Handle(Array::New(2 * num_variables));
@@ skipping 339 matching lines @@
 
 
 DebuggerStackTrace* Debugger::CollectStackTrace() {
   Isolate* isolate = Isolate::Current();
   DebuggerStackTrace* stack_trace = new DebuggerStackTrace(8);
   Context& ctx = Context::Handle(isolate->top_context());
   Code& code = Code::Handle(isolate);
   StackFrameIterator iterator(false);
   StackFrame* frame = iterator.NextFrame();
   bool get_saved_context = false;
+  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 (get_saved_context && !activation->code().is_optimized()) {
-        ctx = activation->GetSavedContext();
+      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 {
+        if (get_saved_context) {
+          ctx = activation->GetSavedContext();
+        }
+        activation->SetContext(ctx);
       }
-      activation->SetContext(ctx);
       stack_trace->AddActivation(activation);
       get_saved_context = activation->function().IsClosureFunction();
     } else if (frame->IsEntryFrame()) {
       ctx = reinterpret_cast<EntryFrame*>(frame)->SavedContext();
       get_saved_context = false;
     }
     frame = iterator.NextFrame();
   }
   return stack_trace;
 }
@@ skipping 832 matching lines @@
 }
 
 
 void Debugger::RegisterCodeBreakpoint(CodeBreakpoint* bpt) {
   ASSERT(bpt->next() == NULL);
   bpt->set_next(code_breakpoints_);
   code_breakpoints_ = bpt;
 }
 
 }  // namespace dart