[debugger] Use code offsets from frame summary in FromFrame Function.

src/debug/debug.cc

Index: src/debug/debug.cc
diff --git a/src/debug/debug.cc b/src/debug/debug.cc
index 4bd5fa0cf0cd64b761d4bacb59195ac52b2ab28d..55bab373890ed733354780623f058675725d0047 100644
--- a/src/debug/debug.cc
+++ b/src/debug/debug.cc
@@ -149,13 +149,22 @@ BreakLocation BreakLocation::FromCodeOffset(Handle<DebugInfo> debug_info,
   return it.GetBreakLocation();
 }
 
+// Put GetFirstFrameSummary Declaration here as FromFrame use it.
+FrameSummary GetFirstFrameSummary(JavaScriptFrame* frame);

[Yang, 2016/02/05 08:49:34]

Can you simply move the function definition to here?

 BreakLocation BreakLocation::FromFrame(Handle<DebugInfo> debug_info,
                                        JavaScriptFrame* frame) {
   // Code offset to the instruction after the current one, possibly a break
   // location as well. So the "- 1" to exclude it from the search.
-  Code* code = frame->LookupCode();
-  int code_offset = static_cast<int>(frame->pc() - code->instruction_start());
-  return FromCodeOffset(debug_info, code_offset - 1);
+  // Get code offset from the unoptimized code.
+  FrameSummary summary = GetFirstFrameSummary(frame);
+  Handle<JSFunction> function(summary.function());

[Yang, 2016/02/05 08:49:34]

You don't need to refresh the frame summary here. We only do that at other call
sites because we may not have the debug info, so we may have to recompile the
code. Here we already have the debug info.

+  Handle<SharedFunctionInfo> shared(function->shared());
+  // Refresh frame summary if the code has been recompiled for debugging.
+  if (AbstractCode::cast(shared->code()) != *summary.abstract_code()) {
+    summary = GetFirstFrameSummary(frame);
+  }
+
+  return FromCodeOffset(debug_info, summary.code_offset() - 1);
 }
 
 // Find the break point at the supplied address, or the closest one before