text: // Copyright 2014 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 <vector>
  
  #include "src/arguments-inl.h"
  #include "src/compiler.h"
  #include "src/counters.h"
  #include "src/debug/debug-coverage.h"
  #include "src/debug/debug-evaluate.h"
  #include "src/debug/debug-frames.h"
  #include "src/debug/debug-scopes.h"
  #include "src/debug/debug.h"
  #include "src/debug/liveedit.h"
  #include "src/frames-inl.h"
  #include "src/globals.h"
  #include "src/interpreter/bytecode-array-accessor.h"
  #include "src/interpreter/bytecodes.h"
  #include "src/interpreter/interpreter.h"
  #include "src/isolate-inl.h"
  #include "src/objects/debug-objects-inl.h"
  #include "src/objects/heap-object-inl.h"
  #include "src/objects/js-collection-inl.h"
  #include "src/objects/js-generator-inl.h"
  #include "src/objects/js-promise-inl.h"
  #include "src/runtime/runtime-utils.h"
  #include "src/runtime/runtime.h"
  #include "src/snapshot/snapshot.h"
  #include "src/wasm/wasm-objects-inl.h"
  
  namespace v8 {
  namespace internal {
  
  RUNTIME_FUNCTION_RETURN_PAIR(Runtime_DebugBreakOnBytecode) {
    using interpreter::Bytecode;
    using interpreter::Bytecodes;
    using interpreter::OperandScale;
  
    SealHandleScope shs(isolate);
    DCHECK_EQ(1, args.length());
    CONVERT_ARG_HANDLE_CHECKED(Object, value, 0);
    HandleScope scope(isolate);
  
    // Return value can be changed by debugger. Last set value will be used as
    // return value.
    ReturnValueScope result_scope(isolate->debug());
    isolate->debug()->set_return_value(*value);
  
    // Get the top-most JavaScript frame.
    JavaScriptFrameIterator it(isolate);
    if (isolate->debug_execution_mode() == DebugInfo::kBreakpoints) {
      isolate->debug()->Break(it.frame(),
                              handle(it.frame()->function(), isolate));
    }
  
    // If we are dropping frames, there is no need to get a return value or
    // bytecode, since we will be restarting execution at a different frame.
    if (isolate->debug()->will_restart()) {
      return MakePair(ReadOnlyRoots(isolate).undefined_value(),
                      Smi::FromInt(static_cast<uint8_t>(Bytecode::kIllegal)));
    }
  
    // Return the handler from the original bytecode array.
    DCHECK(it.frame()->is_interpreted());
    InterpretedFrame* interpreted_frame =
        reinterpret_cast<InterpretedFrame*>(it.frame());
    SharedFunctionInfo shared = interpreted_frame->function()->shared();
    BytecodeArray bytecode_array = shared->GetBytecodeArray();
    int bytecode_offset = interpreted_frame->GetBytecodeOffset();
    Bytecode bytecode = Bytecodes::FromByte(bytecode_array->get(bytecode_offset));
  
    bool side_effect_check_failed = false;
    if (isolate->debug_execution_mode() == DebugInfo::kSideEffects) {
      side_effect_check_failed =
          !isolate->debug()->PerformSideEffectCheckAtBytecode(interpreted_frame);
    }
  
    if (Bytecodes::Returns(bytecode)) {
      // If we are returning (or suspending), reset the bytecode array on the
      // interpreted stack frame to the non-debug variant so that the interpreter
      // entry trampoline sees the return/suspend bytecode rather than the
      // DebugBreak.
      interpreted_frame->PatchBytecodeArray(bytecode_array);
    }
  
    // We do not have to deal with operand scale here. If the bytecode at the
    // break is prefixed by operand scaling, we would have patched over the
    // scaling prefix. We now simply dispatch to the handler for the prefix.
    // We need to deserialize now to ensure we don't hit the debug break again
    // after deserializing.
    OperandScale operand_scale = OperandScale::kSingle;
    isolate->interpreter()->GetBytecodeHandler(bytecode, operand_scale);
  
    if (side_effect_check_failed) {
      return MakePair(ReadOnlyRoots(isolate).exception(),
                      Smi::FromInt(static_cast<uint8_t>(bytecode)));
    }
    Object* interrupt_object = isolate->stack_guard()->HandleInterrupts();
    if (interrupt_object->IsException(isolate)) {
      return MakePair(interrupt_object,
                      Smi::FromInt(static_cast<uint8_t>(bytecode)));
    }
    return MakePair(isolate->debug()->return_value(),
                    Smi::FromInt(static_cast<uint8_t>(bytecode)));
  }
  
  RUNTIME_FUNCTION(Runtime_DebugBreakAtEntry) {
    HandleScope scope(isolate);
    DCHECK_EQ(1, args.length());
    CONVERT_ARG_HANDLE_CHECKED(JSFunction, function, 0);
    USE(function);
  
    DCHECK(function->shared()->HasDebugInfo());
    DCHECK(function->shared()->GetDebugInfo()->BreakAtEntry());
  
    // Get the top-most JavaScript frame.
    JavaScriptFrameIterator it(isolate);
    DCHECK_EQ(*function, it.frame()->function());
    isolate->debug()->Break(it.frame(), function);
  
    return ReadOnlyRoots(isolate).undefined_value();
  }
  
  RUNTIME_FUNCTION(Runtime_HandleDebuggerStatement) {
    SealHandleScope shs(isolate);
    DCHECK_EQ(0, args.length());
    if (isolate->debug()->break_points_active()) {
      isolate->debug()->HandleDebugBreak(kIgnoreIfTopFrameBlackboxed);
    }
    return isolate->stack_guard()->HandleInterrupts();
  }
  
  RUNTIME_FUNCTION(Runtime_ScheduleBreak) {
    SealHandleScope shs(isolate);
    DCHECK_EQ(0, args.length());
    isolate->RequestInterrupt(
        [](v8::Isolate* isolate, void*) { v8::debug::BreakRightNow(isolate); },
        nullptr);
    return ReadOnlyRoots(isolate).undefined_value();
  }
  
  template <class IteratorType>
  static MaybeHandle<JSArray> GetIteratorInternalProperties(
      Isolate* isolate, Handle<IteratorType> object) {
    Factory* factory = isolate->factory();
    Handle<IteratorType> iterator = Handle<IteratorType>::cast(object);
    const char* kind = nullptr;
    switch (iterator->map()->instance_type()) {
      case JS_MAP_KEY_ITERATOR_TYPE:
        kind = "keys";
        break;
      case JS_MAP_KEY_VALUE_ITERATOR_TYPE:
      case JS_SET_KEY_VALUE_ITERATOR_TYPE:
        kind = "entries";
        break;
      case JS_MAP_VALUE_ITERATOR_TYPE:
      case JS_SET_VALUE_ITERATOR_TYPE:
        kind = "values";
        break;
      default:
        UNREACHABLE();
    }
  
    Handle<FixedArray> result = factory->NewFixedArray(2 * 3);
    Handle<String> has_more =
        factory->NewStringFromAsciiChecked("[[IteratorHasMore]]");
    result->set(0, *has_more);
    result->set(1, isolate->heap()->ToBoolean(iterator->HasMore()));
  
    Handle<String> index =
        factory->NewStringFromAsciiChecked("[[IteratorIndex]]");
    result->set(2, *index);
    result->set(3, iterator->index());
  
    Handle<String> iterator_kind =
        factory->NewStringFromAsciiChecked("[[IteratorKind]]");
    result->set(4, *iterator_kind);
    Handle<String> kind_str = factory->NewStringFromAsciiChecked(kind);
    result->set(5, *kind_str);
    return factory->NewJSArrayWithElements(result);
  }
  
  
  MaybeHandle<JSArray> Runtime::GetInternalProperties(Isolate* isolate,
                                                      Handle<Object> object) {
    Factory* factory = isolate->factory();
    if (object->IsJSBoundFunction()) {
      Handle<JSBoundFunction> function = Handle<JSBoundFunction>::cast(object);
  
      Handle<FixedArray> result = factory->NewFixedArray(2 * 3);
      Handle<String> target =
          factory->NewStringFromAsciiChecked("[[TargetFunction]]");
      result->set(0, *target);
      result->set(1, function->bound_target_function());
  
      Handle<String> bound_this =
          factory->NewStringFromAsciiChecked("[[BoundThis]]");
      result->set(2, *bound_this);
      result->set(3, function->bound_this());
  
      Handle<String> bound_args =
          factory->NewStringFromAsciiChecked("[[BoundArgs]]");
      result->set(4, *bound_args);
      Handle<FixedArray> bound_arguments =
          factory->CopyFixedArray(handle(function->bound_arguments(), isolate));
      Handle<JSArray> arguments_array =
          factory->NewJSArrayWithElements(bound_arguments);
      result->set(5, *arguments_array);
      return factory->NewJSArrayWithElements(result);
    } else if (object->IsJSMapIterator()) {
      Handle<JSMapIterator> iterator = Handle<JSMapIterator>::cast(object);
      return GetIteratorInternalProperties(isolate, iterator);
    } else if (object->IsJSSetIterator()) {
      Handle<JSSetIterator> iterator = Handle<JSSetIterator>::cast(object);
      return GetIteratorInternalProperties(isolate, iterator);
    } else if (object->IsJSGeneratorObject()) {
      Handle<JSGeneratorObject> generator =
          Handle<JSGeneratorObject>::cast(object);
  
      const char* status = "suspended";
      if (generator->is_closed()) {
        status = "closed";
      } else if (generator->is_executing()) {
        status = "running";
      } else {
        DCHECK(generator->is_suspended());
      }
  
      Handle<FixedArray> result = factory->NewFixedArray(2 * 3);
      Handle<String> generator_status =
          factory->NewStringFromAsciiChecked("[[GeneratorStatus]]");
      result->set(0, *generator_status);
      Handle<String> status_str = factory->NewStringFromAsciiChecked(status);
      result->set(1, *status_str);
  
      Handle<String> function =
          factory->NewStringFromAsciiChecked("[[GeneratorFunction]]");
      result->set(2, *function);
      result->set(3, generator->function());
  
      Handle<String> receiver =
          factory->NewStringFromAsciiChecked("[[GeneratorReceiver]]");
      result->set(4, *receiver);
      result->set(5, generator->receiver());
      return factory->NewJSArrayWithElements(result);
    } else if (object->IsJSPromise()) {
      Handle<JSPromise> promise = Handle<JSPromise>::cast(object);
      const char* status = JSPromise::Status(promise->status());
      Handle<FixedArray> result = factory->NewFixedArray(2 * 2);
      Handle<String> promise_status =
          factory->NewStringFromAsciiChecked("[[PromiseStatus]]");
      result->set(0, *promise_status);
      Handle<String> status_str = factory->NewStringFromAsciiChecked(status);
      result->set(1, *status_str);
  
      Handle<Object> value_obj(promise->status() == Promise::kPending
                                   ? ReadOnlyRoots(isolate).undefined_value()
                                   : promise->result(),
                               isolate);
      Handle<String> promise_value =
          factory->NewStringFromAsciiChecked("[[PromiseValue]]");
      result->set(2, *promise_value);
      result->set(3, *value_obj);
      return factory->NewJSArrayWithElements(result);
    } else if (object->IsJSProxy()) {
      Handle<JSProxy> js_proxy = Handle<JSProxy>::cast(object);
      Handle<FixedArray> result = factory->NewFixedArray(3 * 2);
  
      Handle<String> handler_str =
          factory->NewStringFromAsciiChecked("[[Handler]]");
      result->set(0, *handler_str);
      result->set(1, js_proxy->handler());
  
      Handle<String> target_str =
          factory->NewStringFromAsciiChecked("[[Target]]");
      result->set(2, *target_str);
      result->set(3, js_proxy->target());
  
      Handle<String> is_revoked_str =
          factory->NewStringFromAsciiChecked("[[IsRevoked]]");
      result->set(4, *is_revoked_str);
      result->set(5, isolate->heap()->ToBoolean(js_proxy->IsRevoked()));
      return factory->NewJSArrayWithElements(result);
    } else if (object->IsJSValue()) {
      Handle<JSValue> js_value = Handle<JSValue>::cast(object);
  
      Handle<FixedArray> result = factory->NewFixedArray(2);
      Handle<String> primitive_value =
          factory->NewStringFromAsciiChecked("[[PrimitiveValue]]");
      result->set(0, *primitive_value);
      result->set(1, js_value->value());
      return factory->NewJSArrayWithElements(result);
    }
    return factory->NewJSArray(0);
  }
  
  RUNTIME_FUNCTION(Runtime_GetGeneratorScopeCount) {
    HandleScope scope(isolate);
    DCHECK_EQ(1, args.length());
  
    if (!args[0]->IsJSGeneratorObject()) return Smi::kZero;
  
    // Check arguments.
    CONVERT_ARG_HANDLE_CHECKED(JSGeneratorObject, gen, 0);
  
    // Only inspect suspended generator scopes.
    if (!gen->is_suspended()) {
      return Smi::kZero;
    }
  
    // Count the visible scopes.
    int n = 0;
    for (ScopeIterator it(isolate, gen); !it.Done(); it.Next()) {
      n++;
    }
  
    return Smi::FromInt(n);
  }
  
  RUNTIME_FUNCTION(Runtime_GetGeneratorScopeDetails) {
    HandleScope scope(isolate);
    DCHECK_EQ(2, args.length());
  
    if (!args[0]->IsJSGeneratorObject()) {
      return ReadOnlyRoots(isolate).undefined_value();
    }
  
    // Check arguments.
    CONVERT_ARG_HANDLE_CHECKED(JSGeneratorObject, gen, 0);
    CONVERT_NUMBER_CHECKED(int, index, Int32, args[1]);
  
    // Only inspect suspended generator scopes.
    if (!gen->is_suspended()) {
      return ReadOnlyRoots(isolate).undefined_value();
    }
  
    // Find the requested scope.
    int n = 0;
    ScopeIterator it(isolate, gen);
    for (; !it.Done() && n < index; it.Next()) {
      n++;
    }
    if (it.Done()) {
      return ReadOnlyRoots(isolate).undefined_value();
    }
  
    return *it.MaterializeScopeDetails();
  }
  
  static bool SetScopeVariableValue(ScopeIterator* it, int index,
                                    Handle<String> variable_name,
                                    Handle<Object> new_value) {
    for (int n = 0; !it->Done() && n < index; it->Next()) {
      n++;
    }
    if (it->Done()) {
      return false;
    }
    return it->SetVariableValue(variable_name, new_value);
  }
  
  // Change variable value in closure or local scope
  // args[0]: number or JsFunction: break id or function
  // args[1]: number: scope index
  // args[2]: string: variable name
  // args[3]: object: new value
  //
  // Return true if success and false otherwise
  RUNTIME_FUNCTION(Runtime_SetGeneratorScopeVariableValue) {
    HandleScope scope(isolate);
    DCHECK_EQ(4, args.length());
    CONVERT_ARG_HANDLE_CHECKED(JSGeneratorObject, gen, 0);
    CONVERT_NUMBER_CHECKED(int, index, Int32, args[1]);
    CONVERT_ARG_HANDLE_CHECKED(String, variable_name, 2);
    CONVERT_ARG_HANDLE_CHECKED(Object, new_value, 3);
    ScopeIterator it(isolate, gen);
    bool res = SetScopeVariableValue(&it, index, variable_name, new_value);
    return isolate->heap()->ToBoolean(res);
  }
  
  
  RUNTIME_FUNCTION(Runtime_GetBreakLocations) {
    HandleScope scope(isolate);
    DCHECK_EQ(1, args.length());
    CHECK(isolate->debug()->is_active());
    CONVERT_ARG_HANDLE_CHECKED(JSFunction, fun, 0);
  
    Handle<SharedFunctionInfo> shared(fun->shared(), isolate);
    // Find the number of break points
    Handle<Object> break_locations =
        Debug::GetSourceBreakLocations(isolate, shared);
    if (break_locations->IsUndefined(isolate)) {
      return ReadOnlyRoots(isolate).undefined_value();
    }
    // Return array as JS array
    return *isolate->factory()->NewJSArrayWithElements(
        Handle<FixedArray>::cast(break_locations));
  }
  
  
  // Returns the state of break on exceptions
  // args[0]: boolean indicating uncaught exceptions
  RUNTIME_FUNCTION(Runtime_IsBreakOnException) {
    HandleScope scope(isolate);
    DCHECK_EQ(1, args.length());
    CONVERT_NUMBER_CHECKED(uint32_t, type_arg, Uint32, args[0]);
  
    ExceptionBreakType type = static_cast<ExceptionBreakType>(type_arg);
    bool result = isolate->debug()->IsBreakOnException(type);
    return Smi::FromInt(result);
  }
  
  // Clear all stepping set by PrepareStep.
  RUNTIME_FUNCTION(Runtime_ClearStepping) {
    HandleScope scope(isolate);
    DCHECK_EQ(0, args.length());
    CHECK(isolate->debug()->is_active());
    isolate->debug()->ClearStepping();
    return ReadOnlyRoots(isolate).undefined_value();
  }
  
  RUNTIME_FUNCTION(Runtime_DebugGetLoadedScriptIds) {
    HandleScope scope(isolate);
    DCHECK_EQ(0, args.length());
  
    Handle<FixedArray> instances;
    {
      DebugScope debug_scope(isolate->debug());
      // Fill the script objects.
      instances = isolate->debug()->GetLoadedScripts();
    }
  
    // Convert the script objects to proper JS objects.
    for (int i = 0; i < instances->length(); i++) {
      Handle<Script> script(Script::cast(instances->get(i)), isolate);
      instances->set(i, Smi::FromInt(script->id()));
    }
  
    // Return result as a JS array.
    return *isolate->factory()->NewJSArrayWithElements(instances);
  }
  
  
  RUNTIME_FUNCTION(Runtime_FunctionGetInferredName) {
    SealHandleScope shs(isolate);
    DCHECK_EQ(1, args.length());
  
    CONVERT_ARG_CHECKED(Object, f, 0);
    if (f->IsJSFunction()) {
      return JSFunction::cast(f)->shared()->inferred_name();
    }
    return ReadOnlyRoots(isolate).empty_string();
  }
  
  
  // Performs a GC.
  // Presently, it only does a full GC.
  RUNTIME_FUNCTION(Runtime_CollectGarbage) {
    SealHandleScope shs(isolate);
    DCHECK_EQ(1, args.length());
    isolate->heap()->PreciseCollectAllGarbage(Heap::kNoGCFlags,
                                              GarbageCollectionReason::kRuntime);
    return ReadOnlyRoots(isolate).undefined_value();
  }
  
  
  // Gets the current heap usage.
  RUNTIME_FUNCTION(Runtime_GetHeapUsage) {
    SealHandleScope shs(isolate);
    DCHECK_EQ(0, args.length());
    int usage = static_cast<int>(isolate->heap()->SizeOfObjects());
    if (!Smi::IsValid(usage)) {
      return *isolate->factory()->NewNumberFromInt(usage);
    }
    return Smi::FromInt(usage);
  }
  
  namespace {
  
  int ScriptLinePosition(Handle<Script> script, int line) {
    if (line < 0) return -1;
  
    if (script->type() == Script::TYPE_WASM) {
      return WasmModuleObject::cast(script->wasm_module_object())
          ->GetFunctionOffset(line);
    }
  
    Script::InitLineEnds(script);
  
    FixedArray line_ends_array = FixedArray::cast(script->line_ends());
    const int line_count = line_ends_array->length();
    DCHECK_LT(0, line_count);
  
    if (line == 0) return 0;
    // If line == line_count, we return the first position beyond the last line.
    if (line > line_count) return -1;
    return Smi::ToInt(line_ends_array->get(line - 1)) + 1;
  }
  
  int ScriptLinePositionWithOffset(Handle<Script> script, int line, int offset) {
    if (line < 0 || offset < 0) return -1;
  
    if (line == 0 || offset == 0)
      return ScriptLinePosition(script, line) + offset;
  
    Script::PositionInfo info;
    if (!Script::GetPositionInfo(script, offset, &info, Script::NO_OFFSET)) {
      return -1;
    }
  
    const int total_line = info.line + line;
    return ScriptLinePosition(script, total_line);
  }
  
  Handle<Object> GetJSPositionInfo(Handle<Script> script, int position,
                                   Script::OffsetFlag offset_flag,
                                   Isolate* isolate) {
    Script::PositionInfo info;
    if (!Script::GetPositionInfo(script, position, &info, offset_flag)) {
      return isolate->factory()->null_value();
    }
  
    Handle<String> source = handle(String::cast(script->source()), isolate);
    Handle<String> sourceText = script->type() == Script::TYPE_WASM
                                    ? isolate->factory()->empty_string()
                                    : isolate->factory()->NewSubString(
                                          source, info.line_start, info.line_end);
  
    Handle<JSObject> jsinfo =
        isolate->factory()->NewJSObject(isolate->object_function());
  
    JSObject::AddProperty(isolate, jsinfo, isolate->factory()->script_string(),
                          script, NONE);
    JSObject::AddProperty(isolate, jsinfo, isolate->factory()->position_string(),
                          handle(Smi::FromInt(position), isolate), NONE);
    JSObject::AddProperty(isolate, jsinfo, isolate->factory()->line_string(),
                          handle(Smi::FromInt(info.line), isolate), NONE);
    JSObject::AddProperty(isolate, jsinfo, isolate->factory()->column_string(),
                          handle(Smi::FromInt(info.column), isolate), NONE);
    JSObject::AddProperty(isolate, jsinfo,
                          isolate->factory()->sourceText_string(), sourceText,
                          NONE);
  
    return jsinfo;
  }
  
  Handle<Object> ScriptLocationFromLine(Isolate* isolate, Handle<Script> script,
                                        Handle<Object> opt_line,
                                        Handle<Object> opt_column,
                                        int32_t offset) {
    // Line and column are possibly undefined and we need to handle these cases,
    // additionally subtracting corresponding offsets.
  
    int32_t line = 0;
    if (!opt_line->IsNullOrUndefined(isolate)) {
      CHECK(opt_line->IsNumber());
      line = NumberToInt32(*opt_line) - script->line_offset();
    }
  
    int32_t column = 0;
    if (!opt_column->IsNullOrUndefined(isolate)) {
      CHECK(opt_column->IsNumber());
      column = NumberToInt32(*opt_column);
      if (line == 0) column -= script->column_offset();
    }
  
    int line_position = ScriptLinePositionWithOffset(script, line, offset);
    if (line_position < 0 || column < 0) return isolate->factory()->null_value();
  
    return GetJSPositionInfo(script, line_position + column, Script::NO_OFFSET,
                             isolate);
  }
  
  // Slow traversal over all scripts on the heap.
  bool GetScriptById(Isolate* isolate, int needle, Handle<Script>* result) {
    Script::Iterator iterator(isolate);
    for (Script script = iterator.Next(); !script.is_null();
         script = iterator.Next()) {
      if (script->id() == needle) {
        *result = handle(script, isolate);
        return true;
      }
    }
  
    return false;
  }
  
  }  // namespace
  
  // TODO(5530): Rename once conflicting function has been deleted.
  RUNTIME_FUNCTION(Runtime_ScriptLocationFromLine2) {
    HandleScope scope(isolate);
    DCHECK_EQ(4, args.length());
    CONVERT_NUMBER_CHECKED(int32_t, scriptid, Int32, args[0]);
    CONVERT_ARG_HANDLE_CHECKED(Object, opt_line, 1);
    CONVERT_ARG_HANDLE_CHECKED(Object, opt_column, 2);
    CONVERT_NUMBER_CHECKED(int32_t, offset, Int32, args[3]);
  
    Handle<Script> script;
    CHECK(GetScriptById(isolate, scriptid, &script));
  
    return *ScriptLocationFromLine(isolate, script, opt_line, opt_column, offset);
  }
  
  // On function call, depending on circumstances, prepare for stepping in,
  // or perform a side effect check.
  RUNTIME_FUNCTION(Runtime_DebugOnFunctionCall) {
    HandleScope scope(isolate);
    DCHECK_EQ(2, args.length());
    CONVERT_ARG_HANDLE_CHECKED(JSFunction, fun, 0);
    CONVERT_ARG_HANDLE_CHECKED(Object, receiver, 1);
    if (isolate->debug()->needs_check_on_function_call()) {
      // Ensure that the callee will perform debug check on function call too.
      Deoptimizer::DeoptimizeFunction(*fun);
      if (isolate->debug()->last_step_action() >= StepIn ||
          isolate->debug()->break_on_next_function_call()) {
        DCHECK_EQ(isolate->debug_execution_mode(), DebugInfo::kBreakpoints);
        isolate->debug()->PrepareStepIn(fun);
      }
      if (isolate->debug_execution_mode() == DebugInfo::kSideEffects &&
          !isolate->debug()->PerformSideEffectCheck(fun, receiver)) {
        return ReadOnlyRoots(isolate).exception();
      }
    }
    return ReadOnlyRoots(isolate).undefined_value();
  }
  
  // Set one shot breakpoints for the suspended generator object.
  RUNTIME_FUNCTION(Runtime_DebugPrepareStepInSuspendedGenerator) {
    HandleScope scope(isolate);
    DCHECK_EQ(0, args.length());
    isolate->debug()->PrepareStepInSuspendedGenerator();
    return ReadOnlyRoots(isolate).undefined_value();
  }
  
  RUNTIME_FUNCTION(Runtime_DebugPushPromise) {
    DCHECK_EQ(1, args.length());
    HandleScope scope(isolate);
    CONVERT_ARG_HANDLE_CHECKED(JSObject, promise, 0);
    isolate->PushPromise(promise);
    return ReadOnlyRoots(isolate).undefined_value();
  }
  
  
  RUNTIME_FUNCTION(Runtime_DebugPopPromise) {
    DCHECK_EQ(0, args.length());
    SealHandleScope shs(isolate);
    isolate->PopPromise();
    return ReadOnlyRoots(isolate).undefined_value();
  }
  
  namespace {
  Handle<JSObject> MakeRangeObject(Isolate* isolate, const CoverageBlock& range) {
    Factory* factory = isolate->factory();
  
    Handle<String> start_string = factory->InternalizeUtf8String("start");
    Handle<String> end_string = factory->InternalizeUtf8String("end");
    Handle<String> count_string = factory->InternalizeUtf8String("count");
  
    Handle<JSObject> range_obj = factory->NewJSObjectWithNullProto();
    JSObject::AddProperty(isolate, range_obj, start_string,
                          factory->NewNumberFromInt(range.start), NONE);
    JSObject::AddProperty(isolate, range_obj, end_string,
                          factory->NewNumberFromInt(range.end), NONE);
    JSObject::AddProperty(isolate, range_obj, count_string,
                          factory->NewNumberFromUint(range.count), NONE);
  
    return range_obj;
  }
  }  // namespace
  
  RUNTIME_FUNCTION(Runtime_DebugCollectCoverage) {
    HandleScope scope(isolate);
    DCHECK_EQ(0, args.length());
    // Collect coverage data.
    std::unique_ptr<Coverage> coverage;
    if (isolate->is_best_effort_code_coverage()) {
      coverage = Coverage::CollectBestEffort(isolate);
    } else {
      coverage = Coverage::CollectPrecise(isolate);
    }
    Factory* factory = isolate->factory();
    // Turn the returned data structure into JavaScript.
    // Create an array of scripts.
    int num_scripts = static_cast<int>(coverage->size());
    // Prepare property keys.
    Handle<FixedArray> scripts_array = factory->NewFixedArray(num_scripts);
    Handle<String> script_string = factory->NewStringFromStaticChars("script");
    for (int i = 0; i < num_scripts; i++) {
      const auto& script_data = coverage->at(i);
      HandleScope inner_scope(isolate);
  
      std::vector<CoverageBlock> ranges;
      int num_functions = static_cast<int>(script_data.functions.size());
      for (int j = 0; j < num_functions; j++) {
        const auto& function_data = script_data.functions[j];
        ranges.emplace_back(function_data.start, function_data.end,
                            function_data.count);
        for (size_t k = 0; k < function_data.blocks.size(); k++) {
          const auto& block_data = function_data.blocks[k];
          ranges.emplace_back(block_data.start, block_data.end, block_data.count);
        }
      }
  
      int num_ranges = static_cast<int>(ranges.size());
      Handle<FixedArray> ranges_array = factory->NewFixedArray(num_ranges);
      for (int j = 0; j < num_ranges; j++) {
        Handle<JSObject> range_object = MakeRangeObject(isolate, ranges[j]);
        ranges_array->set(j, *range_object);
      }
  
      Handle<JSArray> script_obj =
          factory->NewJSArrayWithElements(ranges_array, PACKED_ELEMENTS);
      JSObject::AddProperty(isolate, script_obj, script_string,
                            handle(script_data.script->source(), isolate), NONE);
      scripts_array->set(i, *script_obj);
    }
    return *factory->NewJSArrayWithElements(scripts_array, PACKED_ELEMENTS);
  }
  
  RUNTIME_FUNCTION(Runtime_DebugTogglePreciseCoverage) {
    SealHandleScope shs(isolate);
    CONVERT_BOOLEAN_ARG_CHECKED(enable, 0);
    Coverage::SelectMode(isolate, enable ? debug::Coverage::kPreciseCount
                                         : debug::Coverage::kBestEffort);
    return ReadOnlyRoots(isolate).undefined_value();
  }
  
  RUNTIME_FUNCTION(Runtime_DebugToggleBlockCoverage) {
    SealHandleScope shs(isolate);
    CONVERT_BOOLEAN_ARG_CHECKED(enable, 0);
    Coverage::SelectMode(isolate, enable ? debug::Coverage::kBlockCount
                                         : debug::Coverage::kBestEffort);
    return ReadOnlyRoots(isolate).undefined_value();
  }
  
  RUNTIME_FUNCTION(Runtime_IncBlockCounter) {
    SealHandleScope scope(isolate);
    DCHECK_EQ(2, args.length());
    CONVERT_ARG_CHECKED(JSFunction, function, 0);
    CONVERT_SMI_ARG_CHECKED(coverage_array_slot_index, 1);
  
    // It's quite possible that a function contains IncBlockCounter bytecodes, but
    // no coverage info exists. This happens e.g. by selecting the best-effort
    // coverage collection mode, which triggers deletion of all coverage infos in
    // order to avoid memory leaks.
  
    SharedFunctionInfo shared = function->shared();
    if (shared->HasCoverageInfo()) {
      CoverageInfo coverage_info = shared->GetCoverageInfo();
      coverage_info->IncrementBlockCount(coverage_array_slot_index);
    }
  
    return ReadOnlyRoots(isolate).undefined_value();
  }
  
  RUNTIME_FUNCTION(Runtime_DebugAsyncFunctionEntered) {
    DCHECK_EQ(1, args.length());
    HandleScope scope(isolate);
    CONVERT_ARG_HANDLE_CHECKED(JSPromise, promise, 0);
    isolate->RunPromiseHook(PromiseHookType::kInit, promise,
                            isolate->factory()->undefined_value());
    if (isolate->debug()->is_active()) isolate->PushPromise(promise);
    return ReadOnlyRoots(isolate).undefined_value();
  }
  
  RUNTIME_FUNCTION(Runtime_DebugAsyncFunctionFinished) {
    DCHECK_EQ(2, args.length());
    HandleScope scope(isolate);
    CONVERT_BOOLEAN_ARG_CHECKED(has_suspend, 0);
    CONVERT_ARG_HANDLE_CHECKED(JSPromise, promise, 1);
    isolate->PopPromise();
    if (has_suspend) {
      isolate->OnAsyncFunctionStateChanged(promise,
                                           debug::kAsyncFunctionFinished);
    }
    return *promise;
  }
  
  RUNTIME_FUNCTION(Runtime_DebugAsyncFunctionSuspended) {
    DCHECK_EQ(1, args.length());
    HandleScope scope(isolate);
    CONVERT_ARG_HANDLE_CHECKED(JSPromise, promise, 0);
    isolate->OnAsyncFunctionStateChanged(promise, debug::kAsyncFunctionSuspended);
    return ReadOnlyRoots(isolate).undefined_value();
  }
  
  RUNTIME_FUNCTION(Runtime_LiveEditPatchScript) {
    HandleScope scope(isolate);
    DCHECK_EQ(2, args.length());
    CONVERT_ARG_HANDLE_CHECKED(JSFunction, script_function, 0);
    CONVERT_ARG_HANDLE_CHECKED(String, new_source, 1);
  
    Handle<Script> script(Script::cast(script_function->shared()->script()),
                          isolate);
    v8::debug::LiveEditResult result;
    LiveEdit::PatchScript(isolate, script, new_source, false, &result);
    switch (result.status) {
      case v8::debug::LiveEditResult::COMPILE_ERROR:
        return isolate->Throw(*isolate->factory()->NewStringFromAsciiChecked(
            "LiveEdit failed: COMPILE_ERROR"));
      case v8::debug::LiveEditResult::BLOCKED_BY_RUNNING_GENERATOR:
        return isolate->Throw(*isolate->factory()->NewStringFromAsciiChecked(
            "LiveEdit failed: BLOCKED_BY_RUNNING_GENERATOR"));
      case v8::debug::LiveEditResult::BLOCKED_BY_FUNCTION_ABOVE_BREAK_FRAME:
        return isolate->Throw(*isolate->factory()->NewStringFromAsciiChecked(
            "LiveEdit failed: BLOCKED_BY_FUNCTION_ABOVE_BREAK_FRAME"));
      case v8::debug::LiveEditResult::
          BLOCKED_BY_FUNCTION_BELOW_NON_DROPPABLE_FRAME:
        return isolate->Throw(*isolate->factory()->NewStringFromAsciiChecked(
            "LiveEdit failed: BLOCKED_BY_FUNCTION_BELOW_NON_DROPPABLE_FRAME"));
      case v8::debug::LiveEditResult::BLOCKED_BY_ACTIVE_FUNCTION:
        return isolate->Throw(*isolate->factory()->NewStringFromAsciiChecked(
            "LiveEdit failed: BLOCKED_BY_ACTIVE_FUNCTION"));
      case v8::debug::LiveEditResult::BLOCKED_BY_NEW_TARGET_IN_RESTART_FRAME:
        return isolate->Throw(*isolate->factory()->NewStringFromAsciiChecked(
            "LiveEdit failed: BLOCKED_BY_NEW_TARGET_IN_RESTART_FRAME"));
      case v8::debug::LiveEditResult::FRAME_RESTART_IS_NOT_SUPPORTED:
        return isolate->Throw(*isolate->factory()->NewStringFromAsciiChecked(
            "LiveEdit failed: FRAME_RESTART_IS_NOT_SUPPORTED"));
      case v8::debug::LiveEditResult::OK:
        return ReadOnlyRoots(isolate).undefined_value();
    }
    return ReadOnlyRoots(isolate).undefined_value();
  }
  
  RUNTIME_FUNCTION(Runtime_PerformSideEffectCheckForObject) {
    HandleScope scope(isolate);
    DCHECK_EQ(1, args.length());
    CONVERT_ARG_HANDLE_CHECKED(JSReceiver, object, 0);
  
    DCHECK_EQ(isolate->debug_execution_mode(), DebugInfo::kSideEffects);
    if (!isolate->debug()->PerformSideEffectCheckForObject(object)) {
      DCHECK(isolate->has_pending_exception());
      return ReadOnlyRoots(isolate).exception();
    }
    return ReadOnlyRoots(isolate).undefined_value();
  }
  
  }  // namespace internal
  }  // namespace v8
  