Fix stepping after a breakpoint

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 1976 matching lines @@
   // Don't pause recursively.
   if (IsPaused()) return;
 
   // Check whether we are in a Dart function that the user is
   // interested in. If we saved the frame pointer of a stack frame
   // the user is interested in, we ignore the single step if we are
   // in a callee of that frame. Note that we assume that the stack
   // grows towards lower addresses.
   ActivationFrame* frame = TopDartFrame();
   ASSERT(frame != NULL);
-  if ((stepping_fp_ != 0) && (stepping_fp_ > frame->fp())) {
-    return;
+
+  if (stepping_fp_ != 0) {
+    // There is an "interesting frame" set. Only pause at appropriate
+    // locations in this frame.
+    if (stepping_fp_ > frame->fp()) {
+      // We are in a callee of the frame we're interested in.
+      // Ignore this stepping break.
+      return;
+    } else if (frame->fp() > stepping_fp_) {
+      // We returned from the "interesting frame", there can be no more
+      // stepping breaks for it. Pause at the next appropriate location
+      // and let the user set the "interesting" frame again.
+      stepping_fp_ = 0;
+    }
   }
-  // If an "interesting" frame is set, we are either in that frame
-  // or the program has returned from that frame. Let the user set
-  // the "interesting" frame again next time we pause.
-  stepping_fp_ = 0;
 
   if (!frame->IsDebuggable()) {
     return;
   }
   if (frame->TokenPos() == Scanner::kNoSourcePos) {
     return;
   }
 
   // Don't pause for a single step if there is a breakpoint set
   // at this location.
@@ skipping 299 matching lines @@
 }
 
 
 void Debugger::RegisterCodeBreakpoint(CodeBreakpoint* bpt) {
   ASSERT(bpt->next() == NULL);
   bpt->set_next(code_breakpoints_);
   code_breakpoints_ = bpt;
 }
 
 }  // namespace dart