src/liveedit.cc

// Copyright 2010 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
//       with the distribution.
//     * Neither the name of Google Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


#include "v8.h"

#include "liveedit.h"
#include "compiler.h"
#include "oprofile-agent.h"
#include "scopes.h"
#include "global-handles.h"
#include "debug.h"

namespace v8 {
namespace internal {


#ifdef ENABLE_DEBUGGER_SUPPORT

static void CompileScriptForTracker(Handle<Script> script) {
  const bool is_eval = false;
  const bool is_global = true;
  // TODO(635): support extensions.
  Extension* extension = NULL;

  PostponeInterruptsScope postpone;

  // Only allow non-global compiles for eval.
  ASSERT(is_eval || is_global);

  // Build AST.
  ScriptDataImpl* pre_data = NULL;
  FunctionLiteral* lit = MakeAST(is_global, script, extension, pre_data);

  // Check for parse errors.
  if (lit == NULL) {
    ASSERT(Top::has_pending_exception());
    return;
  }

  // Compile the code.
  CompilationInfo info(lit, script, is_eval);
  Handle<Code> code = MakeCodeForLiveEdit(&info);

  // Check for stack-overflow exceptions.
  if (code.is_null()) {
    Top::StackOverflow();
    return;
  }
}

// Unwraps JSValue object, returning its field "value"
static Handle<Object> UnwrapJSValue(Handle<JSValue> jsValue) {
  return Handle<Object>(jsValue->value());
}

// Wraps any object into a OpaqueReference, that will hide the object
// from JavaScript.
static Handle<JSValue> WrapInJSValue(Object* object) {
  Handle<JSFunction> constructor = Top::opaque_reference_function();
  Handle<JSValue> result =
      Handle<JSValue>::cast(Factory::NewJSObject(constructor));
  result->set_value(object);
  return result;
}

// Simple helper class that creates more or less typed structures over
// JSArray object. This is an adhoc method of passing structures from C++
// to JavaScript.
template<typename S>
class JSArrayBasedStruct {
 public:
  static S Create() {
    Handle<JSArray> array = Factory::NewJSArray(S::kSize_);
    return S(array);
  }
  static S cast(Object* object) {
    JSArray* array = JSArray::cast(object);
    Handle<JSArray> array_handle(array);
    return S(array_handle);
  }
  explicit JSArrayBasedStruct(Handle<JSArray> array) : array_(array) {
  }
  Handle<JSArray> GetJSArray() {
    return array_;
  }
 protected:
  void SetField(int field_position, Handle<Object> value) {
    SetElement(array_, field_position, value);
  }
  void SetSmiValueField(int field_position, int value) {
    SetElement(array_, field_position, Handle<Smi>(Smi::FromInt(value)));
  }
  Object* GetField(int field_position) {
    return array_->GetElement(field_position);
  }
  int GetSmiValueField(int field_position) {
    Object* res = GetField(field_position);
    return Smi::cast(res)->value();
  }
 private:
  Handle<JSArray> array_;
};


// Represents some function compilation details. This structure will be used
// from JavaScript. It contains Code object, which is kept wrapped
// into a BlindReference for sanitizing reasons.
class FunctionInfoWrapper : public JSArrayBasedStruct<FunctionInfoWrapper> {
 public:
  explicit FunctionInfoWrapper(Handle<JSArray> array)
      : JSArrayBasedStruct<FunctionInfoWrapper>(array) {
  }
  void SetInitialProperties(Handle<String> name, int start_position,
                            int end_position, int param_num, int parent_index) {
    HandleScope scope;
    this->SetField(kFunctionNameOffset_, name);
    this->SetSmiValueField(kStartPositionOffset_, start_position);
    this->SetSmiValueField(kEndPositionOffset_, end_position);
    this->SetSmiValueField(kParamNumOffset_, param_num);
    this->SetSmiValueField(kParentIndexOffset_, parent_index);
  }
  void SetFunctionCode(Handle<Code> function_code) {
    Handle<JSValue> wrapper = WrapInJSValue(*function_code);
    this->SetField(kCodeOffset_, wrapper);
  }
  void SetScopeInfo(Handle<JSArray> scope_info_array) {
    this->SetField(kScopeInfoOffset_, scope_info_array);
  }
  int GetParentIndex() {
    return this->GetSmiValueField(kParentIndexOffset_);
  }
  Handle<Code> GetFunctionCode() {
    Handle<Object> raw_result = UnwrapJSValue(Handle<JSValue>(
        JSValue::cast(this->GetField(kCodeOffset_))));
    return Handle<Code>::cast(raw_result);
  }
  int GetStartPosition() {
    return this->GetSmiValueField(kStartPositionOffset_);
  }
  int GetEndPosition() {
    return this->GetSmiValueField(kEndPositionOffset_);
  }

 private:
  static const int kFunctionNameOffset_ = 0;
  static const int kStartPositionOffset_ = 1;
  static const int kEndPositionOffset_ = 2;
  static const int kParamNumOffset_ = 3;
  static const int kCodeOffset_ = 4;
  static const int kScopeInfoOffset_ = 5;
  static const int kParentIndexOffset_ = 6;
  static const int kSize_ = 7;

  friend class JSArrayBasedStruct<FunctionInfoWrapper>;
};

// Wraps SharedFunctionInfo along with some of its fields for passing it
// back to JavaScript. SharedFunctionInfo object itself is additionally
// wrapped into BlindReference for sanitizing reasons.
class SharedInfoWrapper : public JSArrayBasedStruct<SharedInfoWrapper> {
 public:
  explicit SharedInfoWrapper(Handle<JSArray> array)
      : JSArrayBasedStruct<SharedInfoWrapper>(array) {
  }

  void SetProperties(Handle<String> name, int start_position, int end_position,
                     Handle<SharedFunctionInfo> info) {
    HandleScope scope;
    this->SetField(kFunctionNameOffset_, name);
    Handle<JSValue> info_holder = WrapInJSValue(*info);
    this->SetField(kSharedInfoOffset_, info_holder);
    this->SetSmiValueField(kStartPositionOffset_, start_position);
    this->SetSmiValueField(kEndPositionOffset_, end_position);
  }
  Handle<SharedFunctionInfo> GetInfo() {
    Object* element = this->GetField(kSharedInfoOffset_);
    Handle<JSValue> value_wrapper(JSValue::cast(element));
    Handle<Object> raw_result = UnwrapJSValue(value_wrapper);
    return Handle<SharedFunctionInfo>::cast(raw_result);
  }

 private:
  static const int kFunctionNameOffset_ = 0;
  static const int kStartPositionOffset_ = 1;
  static const int kEndPositionOffset_ = 2;
  static const int kSharedInfoOffset_ = 3;
  static const int kSize_ = 4;

  friend class JSArrayBasedStruct<SharedInfoWrapper>;
};

class FunctionInfoListener {
 public:
  FunctionInfoListener() {
    current_parent_index_ = -1;
    len_ = 0;
    result_ = Factory::NewJSArray(10);
  }

  void FunctionStarted(FunctionLiteral* fun) {
    HandleScope scope;
    FunctionInfoWrapper info = FunctionInfoWrapper::Create();
    info.SetInitialProperties(fun->name(), fun->start_position(),
                              fun->end_position(), fun->num_parameters(),
                              current_parent_index_);
    current_parent_index_ = len_;
    SetElement(result_, len_, info.GetJSArray());
    len_++;
  }

  void FunctionDone() {
    HandleScope scope;
    FunctionInfoWrapper info =
        FunctionInfoWrapper::cast(result_->GetElement(current_parent_index_));
    current_parent_index_ = info.GetParentIndex();
  }

  void FunctionScope(Scope* scope) {
    HandleScope handle_scope;

    Handle<JSArray> scope_info_list = Factory::NewJSArray(10);
    int scope_info_length = 0;

    // Saves some description of scope. It stores name and indexes of
    // variables in the whole scope chain. Null-named slots delimit
    // scopes of this chain.
    Scope* outer_scope = scope->outer_scope();
    if (outer_scope == NULL) {
      return;
    }
    do {
      ZoneList<Variable*> list(10);
      outer_scope->CollectUsedVariables(&list);
      int j = 0;
      for (int i = 0; i < list.length(); i++) {
        Variable* var1 = list[i];
        Slot* slot = var1->slot();
        if (slot != NULL && slot->type() == Slot::CONTEXT) {
          if (j != i) {
            list[j] = var1;
          }
          j++;
        }
      }

      // Sort it.
      for (int k = 1; k < j; k++) {
        int l = k;
        for (int m = k + 1; m < j; m++) {
          if (list[l]->slot()->index() > list[m]->slot()->index()) {
            l = m;
          }
        }
        list[k] = list[l];
      }
      for (int i = 0; i < j; i++) {
        SetElement(scope_info_list, scope_info_length, list[i]->name());
        scope_info_length++;
        SetElement(scope_info_list, scope_info_length,
                   Handle<Smi>(Smi::FromInt(list[i]->slot()->index())));
        scope_info_length++;
      }
      SetElement(scope_info_list, scope_info_length,
                 Handle<Object>(Heap::null_value()));
      scope_info_length++;

      outer_scope = outer_scope->outer_scope();
    } while (outer_scope != NULL);

    FunctionInfoWrapper info =
        FunctionInfoWrapper::cast(result_->GetElement(current_parent_index_));
    info.SetScopeInfo(scope_info_list);
  }

  void FunctionCode(Handle<Code> function_code) {
    FunctionInfoWrapper info =
        FunctionInfoWrapper::cast(result_->GetElement(current_parent_index_));
    info.SetFunctionCode(function_code);
  }

  Handle<JSArray> GetResult() {
    return result_;
  }

 private:
  Handle<JSArray> result_;
  int len_;
  int current_parent_index_;
};

static FunctionInfoListener* active_function_info_listener = NULL;

JSArray* LiveEdit::GatherCompileInfo(Handle<Script> script,
                                     Handle<String> source) {
  CompilationZoneScope zone_scope(DELETE_ON_EXIT);

  FunctionInfoListener listener;
  Handle<Object> original_source = Handle<Object>(script->source());
  script->set_source(*source);
  active_function_info_listener = &listener;
  CompileScriptForTracker(script);
  active_function_info_listener = NULL;
  script->set_source(*original_source);

  return *(listener.GetResult());
}


void LiveEdit::WrapSharedFunctionInfos(Handle<JSArray> array) {
  HandleScope scope;
  int len = Smi::cast(array->length())->value();
  for (int i = 0; i < len; i++) {
    Handle<SharedFunctionInfo> info(
        SharedFunctionInfo::cast(array->GetElement(i)));
    SharedInfoWrapper info_wrapper = SharedInfoWrapper::Create();
    Handle<String> name_handle(String::cast(info->name()));
    info_wrapper.SetProperties(name_handle, info->start_position(),
                               info->end_position(), info);
    array->SetElement(i, *(info_wrapper.GetJSArray()));
  }
}


void LiveEdit::ReplaceFunctionCode(Handle<JSArray> new_compile_info_array,
                                 Handle<JSArray> shared_info_array) {
  HandleScope scope;

  FunctionInfoWrapper compile_info_wrapper(new_compile_info_array);
  SharedInfoWrapper shared_info_wrapper(shared_info_array);

  Handle<SharedFunctionInfo> shared_info = shared_info_wrapper.GetInfo();

  shared_info->set_code(*(compile_info_wrapper.GetFunctionCode()),
                        UPDATE_WRITE_BARRIER);
  shared_info->set_start_position(compile_info_wrapper.GetStartPosition());
  shared_info->set_end_position(compile_info_wrapper.GetEndPosition());
  // update breakpoints, original code, constructor stub
}


void LiveEdit::RelinkFunctionToScript(Handle<JSArray> shared_info_array,
                                      Handle<Script> script_handle) {
  SharedInfoWrapper shared_info_wrapper(shared_info_array);
  Handle<SharedFunctionInfo> shared_info = shared_info_wrapper.GetInfo();

  shared_info->set_script(*script_handle);
}


// For a script text change (defined as position_change_array), translates
// position in unchanged text to position in changed text.
// Text change is a set of non-overlapping regions in text, that have changed
// their contents and length. It is specified as array of groups of 3 numbers:
// (change_begin, change_end, change_end_new_position).
// Each group describes a change in text; groups are sorted by change_begin.
// Only position in text beyond any changes may be successfully translated.
// If a positions is inside some region that changed, result is currently
// undefined.
static int TranslatePosition(int original_position,
                             Handle<JSArray> position_change_array) {
  int position_diff = 0;
  int array_len = Smi::cast(position_change_array->length())->value();
  // TODO(635): binary search may be used here
  for (int i = 0; i < array_len; i += 3) {
    int chunk_start =
        Smi::cast(position_change_array->GetElement(i))->value();
    int chunk_end =
        Smi::cast(position_change_array->GetElement(i + 1))->value();
    int chunk_changed_end =
        Smi::cast(position_change_array->GetElement(i + 2))->value();
    position_diff = chunk_changed_end - chunk_end;
    if (original_position < chunk_start) {
      break;
    }
    // Position mustn't be inside a chunk.
    ASSERT(original_position >= chunk_end);
  }

  return original_position + position_diff;
}


void LiveEdit::PatchFunctionPositions(Handle<JSArray> shared_info_array,
                                      Handle<JSArray> position_change_array) {
  SharedInfoWrapper shared_info_wrapper(shared_info_array);
  Handle<SharedFunctionInfo> info = shared_info_wrapper.GetInfo();

  info->set_start_position(TranslatePosition(info->start_position(),
                                             position_change_array));
  info->set_end_position(TranslatePosition(info->end_position(),
                                           position_change_array));

  // Also patch rinfos (both in working code and original code), breakpoints.
}


LiveEditFunctionTracker::LiveEditFunctionTracker(FunctionLiteral* fun) {
  if (active_function_info_listener != NULL) {
    active_function_info_listener->FunctionStarted(fun);
  }
}


LiveEditFunctionTracker::~LiveEditFunctionTracker() {
  if (active_function_info_listener != NULL) {
    active_function_info_listener->FunctionDone();
  }
}


void LiveEditFunctionTracker::RecordFunctionCode(Handle<Code> code) {
  if (active_function_info_listener != NULL) {
    active_function_info_listener->FunctionCode(code);
  }
}


void LiveEditFunctionTracker::RecordFunctionScope(Scope* scope) {
  if (active_function_info_listener != NULL) {
    active_function_info_listener->FunctionScope(scope);
  }
}


bool LiveEditFunctionTracker::IsActive() {
  return active_function_info_listener != NULL;
}


#else  // ENABLE_DEBUGGER_SUPPORT

// This ifdef-else-endif section provides working or stub implementation of
// LiveEditFunctionTracker.
LiveEditFunctionTracker::LiveEditFunctionTracker(FunctionLiteral* fun) {
}


LiveEditFunctionTracker::~LiveEditFunctionTracker() {
}


void LiveEditFunctionTracker::RecordFunctionCode(Handle<Code> code) {
}


void LiveEditFunctionTracker::RecordFunctionScope(Scope* scope) {
}


bool LiveEditFunctionTracker::IsActive() {
  return false;
}

#endif  // ENABLE_DEBUGGER_SUPPORT



} }  // namespace v8::internal