Reapply http://codereview.chromium.org/149542 now that issue with Mac builder...

src/debug.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 316 matching lines @@
     // called. If the executing code has a debug break at the location change
     // the call in the original code as it is the code there that will be
     // executed in place of the debug break call.
     Handle<Code> stub = ComputeCallDebugPrepareStepIn(code->arguments_count());
     if (IsDebugBreak()) {
       original_rinfo()->set_target_address(stub->entry());
     } else {
       rinfo()->set_target_address(stub->entry());
     }
   } else {
-    // Step in through constructs call requires no changes to the running code.
-    ASSERT(RelocInfo::IsConstructCall(rmode()));
+    // Step in through construct call requires no changes to the running code.
+    // Step in through getters/setters should already be prepared as well
+    // because caller of this function (Debug::PrepareStep) is expected to
+    // flood the top frame's function with one shot breakpoints.
+    ASSERT(RelocInfo::IsConstructCall(rmode()) || code->is_inline_cache_stub());
   }
 }
 
 
 // Check whether the break point is at a position which will exit the function.
 bool BreakLocationIterator::IsExit() const {
   return (RelocInfo::IsJSReturn(rmode()));
 }
 
 
@@ skipping 731 matching lines @@
     return;
   }
   Handle<DebugInfo> debug_info = GetDebugInfo(shared);
 
   // Find the break location where execution has stopped.
   BreakLocationIterator it(debug_info, ALL_BREAK_LOCATIONS);
   it.FindBreakLocationFromAddress(frame->pc());
 
   // Compute whether or not the target is a call target.
   bool is_call_target = false;
+  bool is_load_or_store = false;
+  bool is_inline_cache_stub = false;
   if (RelocInfo::IsCodeTarget(it.rinfo()->rmode())) {
     Address target = it.rinfo()->target_address();
     Code* code = Code::GetCodeFromTargetAddress(target);
-    if (code->is_call_stub()) is_call_target = true;
+    if (code->is_call_stub()) {
+      is_call_target = true;
+    }
+    if (code->is_inline_cache_stub()) {
+      is_inline_cache_stub = true;
+      is_load_or_store = !is_call_target;
+    }
   }
 
   // If this is the last break code target step out is the only possibility.
   if (it.IsExit() || step_action == StepOut) {
     // Step out: If there is a JavaScript caller frame, we need to
     // flood it with breakpoints.
     frames_it.Advance();
     if (!frames_it.done()) {
       // Fill the function to return to with one-shot break points.
       JSFunction* function = JSFunction::cast(frames_it.frame()->function());
       FloodWithOneShot(Handle<SharedFunctionInfo>(function->shared()));
     }
-  } else if (!(is_call_target || RelocInfo::IsConstructCall(it.rmode())) ||
-             step_action == StepNext || step_action == StepMin) {
+  } else if (!(is_inline_cache_stub || RelocInfo::IsConstructCall(it.rmode()))
+             || step_action == StepNext || step_action == StepMin) {
     // Step next or step min.
 
     // Fill the current function with one-shot break points.
     FloodWithOneShot(shared);
 
     // Remember source position and frame to handle step next.
     thread_local_.last_statement_position_ =
         debug_info->code()->SourceStatementPosition(frame->pc());
     thread_local_.last_fp_ = frame->fp();
   } else {
     // Fill the current function with one-shot break points even for step in on
     // a call target as the function called might be a native function for
-    // which step in will not stop.
+    // which step in will not stop. It also prepares for stepping in
+    // getters/setters.
     FloodWithOneShot(shared);
 
+    if (is_load_or_store) {
+      // Remember source position and frame to handle step in getter/setter. If
+      // there is a custom getter/setter it will be handled in
+      // Object::Get/SetPropertyWithCallback, otherwise the step action will be
+      // propagated on the next Debug::Break.
+      thread_local_.last_statement_position_ =
+          debug_info->code()->SourceStatementPosition(frame->pc());
+      thread_local_.last_fp_ = frame->fp();
+    }
+
     // Step in or Step in min
     it.PrepareStepIn();
     ActivateStepIn(frame);
   }
 }
 
 
 // Check whether the current debug break should be reported to the debugger. It
 // is used to have step next and step in only report break back to the debugger
 // if on a different frame or in a different statement. In some situations
@@ skipping 1407 matching lines @@
 
 
 void LockingCommandMessageQueue::Clear() {
   ScopedLock sl(lock_);
   queue_.Clear();
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal