Debugger: prepare code for debugging on a per-function basis.

src/heap/objects-visiting-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_VISITING_INL_H_
 #define V8_OBJECTS_VISITING_INL_H_
 
 #include "src/heap/objects-visiting.h"
 
 namespace v8 {
@@ skipping 641 matching lines @@
 template <typename StaticVisitor>
 bool StaticMarkingVisitor<StaticVisitor>::IsFlushable(
     Heap* heap, SharedFunctionInfo* shared_info) {
   // Code is either on stack, in compilation cache or referenced
   // by optimized version of function.
   MarkBit code_mark = Marking::MarkBitFrom(shared_info->code());
   if (Marking::IsBlackOrGrey(code_mark)) {
     return false;
   }
 
+  // Function is subject to debugging, do not flush.
+  if (shared_info->HasDebugInfo()) {

[Michael Starzinger, 2015/07/20 11:33:41]

Ouch, this is scary! Is this a hard requirement? If it is then we need to make
double-sure that flushing decisions are revisited whenever this predicate
changes. Otherwise the SharedFunctionInfo might be enqueued as a flushing
candidate already when the debugger adds breakpoints.

[Yang, 2015/07/20 12:13:47]

Done.

+    return false;
+  }
+
   // The function must be compiled and have the source code available,
   // to be able to recompile it in case we need the function again.
   if (!(shared_info->is_compiled() && HasSourceCode(heap, shared_info))) {
     return false;
   }
 
   // We never flush code for API functions.
   Object* function_data = shared_info->function_data();
   if (function_data->IsFunctionTemplateInfo()) {
     return false;
@@ skipping 163 matching lines @@
 
   RelocIterator it(this, mode_mask);
   for (; !it.done(); it.next()) {
     it.rinfo()->template Visit<StaticVisitor>(heap);
   }
 }
 }
 }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_VISITING_INL_H_