Defer the writing of the source position data to the relocation information...

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 76 matching lines @@
   ASSERT(!RinfoDone());
 
   // Iterate through reloc info for code and original code stopping at each
   // breakable code target.
   bool first = break_point_ == -1;
   while (!RinfoDone()) {
     if (!first) RinfoNext();
     first = false;
     if (RinfoDone()) return;
 
-    // Update the current source position each time a source position is
-    // passed.
+    // Whenever a statement position or (plain) position is passed update the
+    // current value of these.
     if (is_position(rmode())) {
-      position_ = rinfo()->data() - debug_info_->shared()->start_position();
       if (is_statement_position(rmode())) {
         statement_position_ =
             rinfo()->data() - debug_info_->shared()->start_position();
       }
+      // Always update the position as we don't want that to be before the
+      // statement position.
+      position_ = rinfo()->data() - debug_info_->shared()->start_position();
       ASSERT(position_ >= 0);
       ASSERT(statement_position_ >= 0);
     }
 
     // Check for breakable code target. Look in the original code as setting
     // break points can cause the code targets in the running (debugged) code to
     // be of a different kind than in the original code.
     if (is_code_target(rmode())) {
       Address target = original_rinfo()->target_address();
       Code* code = Debug::GetCodeTarget(target);
@@ skipping 856 matching lines @@
   // statement is hit.
   if (thread_local_.last_step_action_ == StepNext ||
       thread_local_.last_step_action_ == StepIn) {
     // Never continue if returning from function.
     if (break_location_iterator->IsExit()) return false;
 
     // Continue if we are still on the same frame and in the same statement.
     int current_statement_position =
         break_location_iterator->code()->SourceStatementPosition(frame->pc());
     return thread_local_.last_fp_ == frame->fp() &&
-           thread_local_.last_statement_position_ == current_statement_position;
+        thread_local_.last_statement_position_ == current_statement_position;
   }
 
   // No step next action - don't continue.
   return false;
 }
 
 
 // Check whether the code object at the specified address is a debug break code
 // object.
 bool Debug::IsDebugBreak(Address addr) {
@@ skipping 977 matching lines @@
 }
 
 
 void LockingMessageQueue::Clear() {
   ScopedLock sl(lock_);
   queue_.Clear();
 }
 
 
 } }  // namespace v8::internal