Debugger: refactor ScopeIterator, FrameInspector and DebugEvaluate.

src/debug/debug-frames.cc

+// Copyright 2015 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-frames.h"
+
+namespace v8 {
+namespace internal {
+
+FrameInspector::FrameInspector(JavaScriptFrame* frame,
+                               int inlined_jsframe_index, Isolate* isolate)
+    : frame_(frame), deoptimized_frame_(NULL), isolate_(isolate) {
+  has_adapted_arguments_ = frame_->has_adapted_arguments();
+  is_bottommost_ = inlined_jsframe_index == 0;
+  is_optimized_ = frame_->is_optimized();
+  // Calculate the deoptimized frame.
+  if (frame->is_optimized()) {
+    // TODO(turbofan): Revisit once we support deoptimization.
+    if (frame->LookupCode()->is_turbofanned() &&
+        frame->function()->shared()->asm_function() &&
+        !FLAG_turbo_asm_deoptimization) {
+      is_optimized_ = false;
+      return;
+    }
+
+    deoptimized_frame_ = Deoptimizer::DebuggerInspectableFrame(
+        frame, inlined_jsframe_index, isolate);
+  }
+}
+
+
+FrameInspector::~FrameInspector() {
+  // Get rid of the calculated deoptimized frame if any.
+  if (deoptimized_frame_ != NULL) {
+    Deoptimizer::DeleteDebuggerInspectableFrame(deoptimized_frame_, isolate_);
+  }
+}
+
+
+int FrameInspector::GetParametersCount() {
+  return is_optimized_ ? deoptimized_frame_->parameters_count()
+                       : frame_->ComputeParametersCount();
+}
+
+
+int FrameInspector::expression_count() {
+  return deoptimized_frame_->expression_count();
+}
+
+
+Object* FrameInspector::GetFunction() {
+  return is_optimized_ ? deoptimized_frame_->GetFunction() : frame_->function();
+}
+
+
+Object* FrameInspector::GetParameter(int index) {
+  return is_optimized_ ? deoptimized_frame_->GetParameter(index)
+                       : frame_->GetParameter(index);
+}
+
+
+Object* FrameInspector::GetExpression(int index) {
+  // TODO(turbofan): Revisit once we support deoptimization.
+  if (frame_->LookupCode()->is_turbofanned() &&
+      frame_->function()->shared()->asm_function() &&
+      !FLAG_turbo_asm_deoptimization) {
+    return isolate_->heap()->undefined_value();
+  }
+  return is_optimized_ ? deoptimized_frame_->GetExpression(index)
+                       : frame_->GetExpression(index);
+}
+
+
+int FrameInspector::GetSourcePosition() {
+  return is_optimized_ ? deoptimized_frame_->GetSourcePosition()
+                       : frame_->LookupCode()->SourcePosition(frame_->pc());
+}
+
+
+bool FrameInspector::IsConstructor() {
+  return is_optimized_ && !is_bottommost_
+             ? deoptimized_frame_->HasConstructStub()
+             : frame_->IsConstructor();
+}
+
+
+Object* FrameInspector::GetContext() {
+  return is_optimized_ ? deoptimized_frame_->GetContext() : frame_->context();
+}
+
+
+// To inspect all the provided arguments the frame might need to be
+// replaced with the arguments frame.
+void FrameInspector::SetArgumentsFrame(JavaScriptFrame* frame) {
+  DCHECK(has_adapted_arguments_);
+  frame_ = frame;
+  is_optimized_ = frame_->is_optimized();
+  DCHECK(!is_optimized_);
+}
+
+
+// Create a plain JSObject which materializes the local scope for the specified
+// frame.
+void FrameInspector::MaterializeStackLocals(Handle<JSObject> target,
+                                            Handle<ScopeInfo> scope_info) {
+  HandleScope scope(isolate_);
+  // First fill all parameters.
+  for (int i = 0; i < scope_info->ParameterCount(); ++i) {
+    // Do not materialize the parameter if it is shadowed by a context local.
+    Handle<String> name(scope_info->ParameterName(i));
+    if (ParameterIsShadowedByContextLocal(scope_info, name)) continue;
+
+    Handle<Object> value(i < GetParametersCount()
+                             ? GetParameter(i)
+                             : isolate_->heap()->undefined_value(),
+                         isolate_);
+    DCHECK(!value->IsTheHole());
+
+    JSObject::SetOwnPropertyIgnoreAttributes(target, name, value, NONE).Check();
+  }
+
+  // Second fill all stack locals.
+  for (int i = 0; i < scope_info->StackLocalCount(); ++i) {
+    if (scope_info->LocalIsSynthetic(i)) continue;
+    Handle<String> name(scope_info->StackLocalName(i));
+    Handle<Object> value(GetExpression(scope_info->StackLocalIndex(i)),
+                         isolate_);
+    if (value->IsTheHole()) value = isolate_->factory()->undefined_value();
+
+    JSObject::SetOwnPropertyIgnoreAttributes(target, name, value, NONE).Check();
+  }
+}
+
+
+void FrameInspector::MaterializeStackLocals(Handle<JSObject> target,
+                                            Handle<JSFunction> function) {
+  Handle<SharedFunctionInfo> shared(function->shared());
+  Handle<ScopeInfo> scope_info(shared->scope_info());
+  MaterializeStackLocals(target, scope_info);
+}
+
+
+void FrameInspector::UpdateStackLocalsFromMaterializedObject(
+    Handle<JSObject> target, Handle<ScopeInfo> scope_info) {
+  if (is_optimized_) {
+    // Optimized frames are not supported. Simply give up.
+    return;
+  }
+
+  HandleScope scope(isolate_);
+
+  // Parameters.
+  for (int i = 0; i < scope_info->ParameterCount(); ++i) {
+    // Shadowed parameters were not materialized.
+    Handle<String> name(scope_info->ParameterName(i));
+    if (ParameterIsShadowedByContextLocal(scope_info, name)) continue;
+
+    DCHECK(!frame_->GetParameter(i)->IsTheHole());
+    Handle<Object> value =
+        Object::GetPropertyOrElement(target, name).ToHandleChecked();
+    frame_->SetParameterValue(i, *value);
+  }
+
+  // Stack locals.
+  for (int i = 0; i < scope_info->StackLocalCount(); ++i) {
+    if (scope_info->LocalIsSynthetic(i)) continue;
+    int index = scope_info->StackLocalIndex(i);
+    if (frame_->GetExpression(index)->IsTheHole()) continue;
+    Handle<Object> value =
+        Object::GetPropertyOrElement(
+            target, handle(scope_info->StackLocalName(i), isolate_))
+            .ToHandleChecked();
+    frame_->SetExpression(index, *value);
+  }
+}
+
+
+bool FrameInspector::ParameterIsShadowedByContextLocal(
+    Handle<ScopeInfo> info, Handle<String> parameter_name) {
+  VariableMode mode;
+  VariableLocation location;
+  InitializationFlag init_flag;
+  MaybeAssignedFlag maybe_assigned_flag;
+  return ScopeInfo::ContextSlotIndex(info, parameter_name, &mode, &location,
+                                     &init_flag, &maybe_assigned_flag) != -1;
+}
+
+
+SaveContext* DebugFrameHelper::FindSavedContextForFrame(
+    Isolate* isolate, JavaScriptFrame* frame) {
+  SaveContext* save = isolate->save_context();
+  while (save != NULL && !save->IsBelowFrame(frame)) {
+    save = save->prev();
+  }
+  DCHECK(save != NULL);
+  return save;
+}
+
+
+int DebugFrameHelper::FindIndexedNonNativeFrame(JavaScriptFrameIterator* it,
+                                                int index) {
+  int count = -1;
+  for (; !it->done(); it->Advance()) {
+    List<FrameSummary> frames(FLAG_max_inlining_levels + 1);
+    it->frame()->Summarize(&frames);
+    for (int i = frames.length() - 1; i >= 0; i--) {
+      // Omit functions from native and extension scripts.
+      if (!frames[i].function()->IsSubjectToDebugging()) continue;
+      if (++count == index) return i;
+    }
+  }
+  return -1;
+}
+
+
+}  // namespace internal
+}  // namespace v8