Deoptimize the world when single stepping.

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 2070 matching lines @@
   InvokeEventHandler(event);
 
   pause_event_ = NULL;
   obj_cache_ = NULL;    // Zone allocated
 }
 
 
 void Debugger::HandleSteppingRequest(DebuggerStackTrace* stack_trace) {
   stepping_fp_ = 0;
   if (resume_action_ == kSingleStep) {
+    // When single stepping, we need to deoptimize because we might be
+    // stepping into optimized code.  This happens in particular if
+    // the isolate has been interrupted, but can happen in other cases
+    // as well.  We need to deoptimize the world in case we are about
+    // to call an optimized function.
+    DeoptimizeWorld();
     isolate_->set_single_step(true);
   } else if (resume_action_ == kStepOver) {
+    DeoptimizeWorld();
     isolate_->set_single_step(true);
     ASSERT(stack_trace->Length() > 0);
     stepping_fp_ = stack_trace->FrameAt(0)->fp();
   } else if (resume_action_ == kStepOut) {
+    DeoptimizeWorld();
     isolate_->set_single_step(true);
     // Find topmost caller that is debuggable.
     for (intptr_t i = 1; i < stack_trace->Length(); i++) {
       ActivationFrame* frame = stack_trace->FrameAt(i);
       if (frame->IsDebuggable()) {
         stepping_fp_ = frame->fp();
         break;
       }
     }
   }
@@ skipping 382 matching lines @@
 }
 
 
 void Debugger::RegisterCodeBreakpoint(CodeBreakpoint* bpt) {
   ASSERT(bpt->next() == NULL);
   bpt->set_next(code_breakpoints_);
   code_breakpoints_ = bpt;
 }
 
 }  // namespace dart