[inspector] added Debugger.getPossibleBreakpoints method

src/debug/debug.cc

Index: src/debug/debug.cc
diff --git a/src/debug/debug.cc b/src/debug/debug.cc
index b3d8347cfd32171d95b40b55b3703532bfa46d37..f029f97507655af28009906cef5830accbc792df 100644
--- a/src/debug/debug.cc
+++ b/src/debug/debug.cc
@@ -1352,6 +1352,94 @@ bool Debug::PrepareFunctionForBreakPoints(Handle<SharedFunctionInfo> shared) {
   return true;
 }
 
+namespace {
+template <typename Iterator>
+void GetBreakablePositions(Iterator& it, int start_position, int end_position,
+                           BreakPositionAlignment alignment,
+                           std::vector<int>& positions) {
+  it.SkipToPosition(start_position, alignment);
+  while (!it.Done() && it.position() < end_position &&
+         it.position() >= start_position) {
+    positions.push_back(alignment == STATEMENT_ALIGNED ? it.statement_position()
+                                                       : it.position());
+    it.Next();
+  }
+}
+}  // namespace
+
+void Debug::FindBreakablePositions(Handle<DebugInfo> debug_info,
+                                   int start_position, int end_position,
+                                   BreakPositionAlignment alignment,
+                                   std::vector<int>& positions) {

[Yang, 2016/11/03 08:03:26]

I've seen you do this elsewhere, but maybe we should change this: Google style
guide suggests not to use reference arguments unless it's const.
https://google.github.io/styleguide/cppguide.html#Reference_Arguments

[kozy, 2016/11/03 17:26:45]

Changed to pointer.

+  if (debug_info->HasDebugCode()) {
+    CodeBreakIterator it(debug_info, ALL_BREAK_LOCATIONS);
+    GetBreakablePositions(it, start_position, end_position, alignment,
+                          positions);
+  } else {
+    DCHECK(debug_info->HasDebugBytecodeArray());
+    BytecodeArrayBreakIterator it(debug_info, ALL_BREAK_LOCATIONS);
+    GetBreakablePositions(it, start_position, end_position, alignment,
+                          positions);
+  }
+}
+
+bool Debug::GetPossibleBreakpoints(Handle<Script> script, int start_position,
+                                   int end_position,
+                                   std::vector<int>& positions) {
+  while (true) {
+    if (!script->shared_function_infos()->IsWeakFixedArray()) return false;
+
+    WeakFixedArray* infos =
+        WeakFixedArray::cast(script->shared_function_infos());
+    HandleScope scope(isolate_);
+    Handle<FixedArray> candidates =

[Yang, 2016/11/03 08:03:26]

Can we simply use a List<Handle<>> here?

[kozy, 2016/11/03 17:26:45]

Done.

+        isolate_->factory()->NewFixedArray(infos->Length());
+    int length = 0;
+    {
+      WeakFixedArray::Iterator iterator(infos);
+      SharedFunctionInfo* info;
+      while ((info = iterator.Next<SharedFunctionInfo>())) {
+        if (info->end_position() < start_position ||
+            info->start_position() >= end_position) {
+          continue;
+        }
+        if (!info->IsSubjectToDebugging()) continue;
+        if (!info->HasDebugCode() && !info->allows_lazy_compilation()) continue;
+        candidates->set(length++, info);
+      }
+    }
+    candidates->Shrink(length);
+
+    bool was_compiled = false;
+    for (int i = 0; i < length; ++i) {
+      SharedFunctionInfo* info = SharedFunctionInfo::cast(candidates->get(i));
+      Handle<SharedFunctionInfo> info_handle(info);
+      if (!info_handle->HasDebugCode()) {
+        if (!Compiler::CompileDebugCode(info_handle)) {
+          return false;
+        } else {
+          was_compiled = true;
+        }
+      }
+      if (!info_handle->HasDebugInfo()) CreateDebugInfo(info_handle);
+    }
+    if (was_compiled) continue;
+
+    for (int i = 0; i < length; ++i) {
+      SharedFunctionInfo* info = SharedFunctionInfo::cast(candidates->get(i));
+      HandleScope scope(isolate_);
+      Handle<SharedFunctionInfo> info_handle(info);
+      CHECK(info->HasDebugInfo());
+      Handle<DebugInfo> debug_info(info_handle->GetDebugInfo());
+      FindBreakablePositions(debug_info, start_position, end_position,
+                             STATEMENT_ALIGNED, positions);
+    }
+    return true;
+  }
+  UNREACHABLE();
+  return false;
+}
+
 void Debug::RecordAsyncFunction(Handle<JSGeneratorObject> generator_object) {
   if (last_step_action() <= StepOut) return;
   if (!IsAsyncFunction(generator_object->function()->shared()->kind())) return;