[interpreter, debugger] replace bytecode on-stack for debugging.

src/debug/debug.cc

 // 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.
 
 #include "src/debug/debug.h"
 
 #include "src/api.h"
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
@@ skipping 1222 matching lines @@
  public:
   explicit RedirectActiveFunctions(SharedFunctionInfo* shared)
       : shared_(shared) {
     DCHECK(shared->HasDebugCode());
   }
 
   void VisitThread(Isolate* isolate, ThreadLocalTop* top) {
     for (JavaScriptFrameIterator it(isolate, top); !it.done(); it.Advance()) {
       JavaScriptFrame* frame = it.frame();
       JSFunction* function = frame->function();
-      if (frame->is_interpreted()) {
-        // TODO(yangguo): replace dispatch table for activated frames.
-        continue;
-      }
       if (frame->is_optimized()) continue;
       if (!function->Inlines(shared_)) continue;
 
+      if (frame->is_interpreted()) {
+        InterpretedFrame* interpreted_frame =
+            reinterpret_cast<InterpretedFrame*>(frame);
+        BytecodeArray* debug_copy =
+            shared_->GetDebugInfo()->abstract_code()->GetBytecodeArray();
+        interpreted_frame->PatchBytecodeArray(debug_copy);
+        continue;
+      }
+
       Code* frame_code = frame->LookupCode();
       DCHECK(frame_code->kind() == Code::FUNCTION);
       if (frame_code->has_debug_break_slots()) continue;
 
       Code* new_code = function->shared()->code();
       Address old_pc = frame->pc();
       Address new_pc = ComputeNewPcForRedirect(new_code, frame_code, old_pc);
 
       if (FLAG_trace_deopt) {
         PrintF("Replacing pc for debugging: %08" V8PRIxPTR " => %08" V8PRIxPTR
@@ skipping 37 matching lines @@
     while (SharedFunctionInfo* shared = iterator.Next()) {
       if (!shared->OptimizedCodeMapIsCleared()) {
         shared->ClearOptimizedCodeMap();
       }
     }
   }
 
   // Make sure we abort incremental marking.
   isolate_->heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask,
                                       "prepare for break points");
+  bool is_interpreted = shared->HasBytecodeArray();
 
   {
+    // TODO(yangguo): with bytecode, we still walk the heap to find all
+    // optimized code for the function to deoptimize. We can probably be
+    // smarter here and avoid the heap walk.
     HeapIterator iterator(isolate_->heap());
     HeapObject* obj;
-    bool include_generators = shared->is_generator();
+    bool include_generators = !is_interpreted && shared->is_generator();
 
     while ((obj = iterator.next())) {
       if (obj->IsJSFunction()) {
         JSFunction* function = JSFunction::cast(obj);
         if (!function->Inlines(*shared)) continue;
         if (function->code()->kind() == Code::OPTIMIZED_FUNCTION) {
           Deoptimizer::DeoptimizeFunction(function);
         }
+        if (is_interpreted) continue;
         if (function->shared() == *shared) functions.Add(handle(function));
       } else if (include_generators && obj->IsJSGeneratorObject()) {
         JSGeneratorObject* generator_obj = JSGeneratorObject::cast(obj);
         if (!generator_obj->is_suspended()) continue;
         JSFunction* function = generator_obj->function();
         if (!function->Inlines(*shared)) continue;
         int pc_offset = generator_obj->continuation();
         int index =
             ComputeContinuationIndexFromPcOffset(function->code(), pc_offset);
         generator_obj->set_continuation(index);
         suspended_generators.Add(handle(generator_obj));
       }
     }
   }
 
-  if (!shared->HasDebugCode()) {
+  // We do not need to replace code to debug bytecode.
+  DCHECK(!is_interpreted || functions.length() == 0);
+  DCHECK(!is_interpreted || suspended_generators.length() == 0);
+
+  // We do not need to recompile to debug bytecode.
+  if (!is_interpreted && !shared->HasDebugCode()) {
     DCHECK(functions.length() > 0);
     if (!Compiler::CompileDebugCode(functions.first())) return false;
   }
 
   for (Handle<JSFunction> const function : functions) {
     function->ReplaceCode(shared->code());
   }
 
   for (Handle<JSGeneratorObject> const generator_obj : suspended_generators) {
     int index = generator_obj->continuation();
@@ skipping 150 matching lines @@
 
   // Return if we already have the debug info for shared.
   if (shared->HasDebugInfo()) return true;
 
   if (function.is_null()) {
     DCHECK(shared->HasDebugCode());
   } else if (!Compiler::Compile(function, CLEAR_EXCEPTION)) {
     return false;
   }
 
-  if (!PrepareFunctionForBreakPoints(shared)) return false;
-
-  CreateDebugInfo(shared);
-
+  if (shared->HasBytecodeArray()) {
+    // To prepare bytecode for debugging, we already need to have the debug
+    // info (containing the debug copy) upfront, but since we do not recompile,
+    // preparing for break points cannot fail.
+    CreateDebugInfo(shared);
+    CHECK(PrepareFunctionForBreakPoints(shared));
+  } else {
+    if (!PrepareFunctionForBreakPoints(shared)) return false;
+    CreateDebugInfo(shared);
+  }
   return true;
 }
 
 
 void Debug::CreateDebugInfo(Handle<SharedFunctionInfo> shared) {
   // Create the debug info object.
   DCHECK(shared->HasDebugCode());
   Handle<DebugInfo> debug_info = isolate_->factory()->NewDebugInfo(shared);
 
   // Add debug info to the list.
@@ skipping 1075 matching lines @@
 }
 
 
 void LockingCommandMessageQueue::Clear() {
   base::LockGuard<base::Mutex> lock_guard(&mutex_);
   queue_.Clear();
 }
 
 }  // namespace internal
 }  // namespace v8