Debugger: allow stepping into resolver from Promise constructor.

R=rossberg@chromium.org
BUG=chromium:451967
LOG=N

Review URL: https://codereview.chromium.org/1404783002

Cr-Commit-Position: refs/heads/master@{#31296}

src/js/array.js

@@ -1185,7 +1185,7 @@ function InnerArrayFilter(f, receiver, array, length) {
   var accumulator = new InternalArray();
   var accumulator_length = 0;
   var is_array = IS_ARRAY(array);
-  var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
+  var stepping = DEBUG_IS_STEPPING(f);
   for (var i = 0; i < length; i++) {
     if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
@@ -1216,7 +1216,7 @@ function InnerArrayForEach(f, receiver, array, length) {
   if (!IS_CALLABLE(f)) throw MakeTypeError(kCalledNonCallable, f);
 
   var is_array = IS_ARRAY(array);
-  var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
+  var stepping = DEBUG_IS_STEPPING(f);
   for (var i = 0; i < length; i++) {
     if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
@@ -1242,7 +1242,7 @@ function InnerArraySome(f, receiver, array, length) {
   if (!IS_CALLABLE(f)) throw MakeTypeError(kCalledNonCallable, f);
 
   var is_array = IS_ARRAY(array);
-  var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
+  var stepping = DEBUG_IS_STEPPING(f);
   for (var i = 0; i < length; i++) {
     if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
@@ -1272,7 +1272,7 @@ function InnerArrayEvery(f, receiver, array, length) {
   if (!IS_CALLABLE(f)) throw MakeTypeError(kCalledNonCallable, f);
 
   var is_array = IS_ARRAY(array);
-  var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
+  var stepping = DEBUG_IS_STEPPING(f);
   for (var i = 0; i < length; i++) {
     if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
@@ -1300,7 +1300,7 @@ function InnerArrayMap(f, receiver, array, length) {
 
   var accumulator = new InternalArray(length);
   var is_array = IS_ARRAY(array);
-  var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
+  var stepping = DEBUG_IS_STEPPING(f);
   for (var i = 0; i < length; i++) {
     if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
@@ -1469,7 +1469,7 @@ function InnerArrayReduce(callback, current, array, length, argumentsLength) {
     throw MakeTypeError(kReduceNoInitial);
   }
 
-  var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(callback);
+  var stepping = DEBUG_IS_STEPPING(callback);
   for (; i < length; i++) {
     if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
@@ -1512,7 +1512,7 @@ function InnerArrayReduceRight(callback, current, array, length,
     throw MakeTypeError(kReduceNoInitial);
   }
 
-  var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(callback);
+  var stepping = DEBUG_IS_STEPPING(callback);
   for (; i >= 0; i--) {
     if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];

src/js/collection.js

@@ -246,7 +246,7 @@ function SetForEach(f, receiver) {
 
   var iterator = new SetIterator(this, ITERATOR_KIND_VALUES);
   var key;
-  var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
+  var stepping = DEBUG_IS_STEPPING(f);
   var value_array = [UNDEFINED];
   while (%SetIteratorNext(iterator, value_array)) {
     if (stepping) %DebugPrepareStepInIfStepping(f);
@@ -429,7 +429,7 @@ function MapForEach(f, receiver) {
   if (!IS_CALLABLE(f)) throw MakeTypeError(kCalledNonCallable, f);
 
   var iterator = new MapIterator(this, ITERATOR_KIND_ENTRIES);
-  var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
+  var stepping = DEBUG_IS_STEPPING(f);
   var value_array = [UNDEFINED, UNDEFINED];
   while (%MapIteratorNext(iterator, value_array)) {
     if (stepping) %DebugPrepareStepInIfStepping(f);

src/js/generator.js

@@ -33,7 +33,7 @@ function GeneratorObjectNext(value) {
   var continuation = %GeneratorGetContinuation(this);
   if (continuation > 0) {
     // Generator is suspended.
-    if (DEBUG_IS_ACTIVE) %DebugPrepareStepInIfStepping(this);
+    DEBUG_PREPARE_STEP_IN_IF_STEPPING(this);
     try {
       return %_GeneratorNext(this, value);
     } catch (e) {

src/js/macros.py

@@ -305,7 +305,7 @@ define NOT_FOUND = -1;
 # Check whether debug is active.
 define DEBUG_IS_ACTIVE = (%_DebugIsActive() != 0);
 macro DEBUG_IS_STEPPING(function) = (%_DebugIsActive() != 0 && %DebugCallbackSupportsStepping(function));
-macro DEBUG_PREPARE_STEP_IN_IF_STEPPING(function) = if (DEBUG_IS_STEPPING(function)) %DebugPrepareStepInIfStepping(function);
+macro DEBUG_PREPARE_STEP_IN_IF_STEPPING(function) = if (%_DebugIsActive() != 0) %DebugPrepareStepInIfStepping(function);
 
 # SharedFlag equivalents
 define kNotShared = false;

src/js/promise.js

@@ -34,7 +34,7 @@ var GlobalPromise = function Promise(resolver) {
     throw MakeTypeError(kResolverNotAFunction, resolver);
   var promise = PromiseInit(this);
   try {
-    %DebugPushPromise(promise, Promise);
+    %DebugPushPromise(promise, Promise, resolver);
     resolver(function(x) { PromiseResolve(promise, x) },
              function(r) { PromiseReject(promise, r) });
   } catch (e) {
@@ -100,8 +100,7 @@ function PromiseCoerce(constructor, x) {
 
 function PromiseHandle(value, handler, deferred) {
   try {
-    %DebugPushPromise(deferred.promise, PromiseHandle);
-    DEBUG_PREPARE_STEP_IN_IF_STEPPING(handler);
+    %DebugPushPromise(deferred.promise, PromiseHandle, handler);
     var result = handler(value);
     if (result === deferred.promise)
       throw MakeTypeError(kPromiseCyclic, result);

src/runtime/runtime-debug.cc

@@ -1612,33 +1612,55 @@ RUNTIME_FUNCTION(Runtime_GetScript) {
 }
 
 
+bool DebugStepInIsActive(Debug* debug) {
+  return debug->is_active() && debug->IsStepping() &&
+         debug->last_step_action() == StepIn;
+}
+
+
 // Check whether debugger is about to step into the callback that is passed
-// to a built-in function such as Array.forEach.
+// to a built-in function such as Array.forEach. This check is done before
+// %DebugPrepareStepInIfStepping and is not strictly necessary. However, if it
+// returns false, we can skip %DebugPrepareStepInIfStepping, useful in loops.
 RUNTIME_FUNCTION(Runtime_DebugCallbackSupportsStepping) {
+  SealHandleScope shs(isolate);
   DCHECK(args.length() == 1);
-  Debug* debug = isolate->debug();
-  if (!debug->is_active() || !debug->IsStepping() ||
-      debug->last_step_action() != StepIn) {
+  if (!DebugStepInIsActive(isolate->debug())) {
     return isolate->heap()->false_value();
   }
-  CONVERT_ARG_CHECKED(Object, callback, 0);
+  CONVERT_ARG_CHECKED(Object, object, 0);
+  RUNTIME_ASSERT(object->IsJSFunction() || object->IsJSGeneratorObject());
   // We do not step into the callback if it's a builtin other than a bound,
   // or not even a function.
-  return isolate->heap()->ToBoolean(
-      callback->IsJSFunction() &&
-      (JSFunction::cast(callback)->IsSubjectToDebugging() ||
-       JSFunction::cast(callback)->shared()->bound()));
+  JSFunction* fun;
+  if (object->IsJSFunction()) {
+    fun = JSFunction::cast(object);
+  } else {
+    fun = JSGeneratorObject::cast(object)->function();
+  }
+  return isolate->heap()->ToBoolean(fun->IsSubjectToDebugging() ||
+                                    fun->shared()->bound());
+}
+
+
+void FloodDebugSubjectWithOneShot(Debug* debug, Handle<JSFunction> function) {
+  if (function->IsSubjectToDebugging() || function->shared()->bound()) {
+    // When leaving the function, step out has been activated, but not performed
+    // if we do not leave the builtin.  To be able to step into the function
+    // again, we need to clear the step out at this point.
+    debug->ClearStepOut();
+    debug->FloodWithOneShotGeneric(function);
+  }
 }
 
 
 // Set one shot breakpoints for the callback function that is passed to a
-// built-in function such as Array.forEach to enable stepping into the callback.
+// built-in function such as Array.forEach to enable stepping into the callback,
+// if we are indeed stepping and the callback is subject to debugging.
 RUNTIME_FUNCTION(Runtime_DebugPrepareStepInIfStepping) {
   DCHECK(args.length() == 1);
-  RUNTIME_ASSERT(isolate->debug()->is_active());
-
   Debug* debug = isolate->debug();
-  if (!debug->IsStepping()) return isolate->heap()->undefined_value();
+  if (!DebugStepInIsActive(debug)) return isolate->heap()->undefined_value();
 
   HandleScope scope(isolate);
   CONVERT_ARG_HANDLE_CHECKED(Object, object, 0);
@@ -1650,21 +1672,23 @@ RUNTIME_FUNCTION(Runtime_DebugPrepareStepInIfStepping) {
     fun = Handle<JSFunction>(
         Handle<JSGeneratorObject>::cast(object)->function(), isolate);
   }
-  // When leaving the function, step out has been activated, but not performed
-  // if we do not leave the builtin.  To be able to step into the function
-  // again, we need to clear the step out at this point.
-  debug->ClearStepOut();
-  debug->FloodWithOneShotGeneric(fun);
+
+  FloodDebugSubjectWithOneShot(debug, fun);
   return isolate->heap()->undefined_value();
 }
 
 
 RUNTIME_FUNCTION(Runtime_DebugPushPromise) {
-  DCHECK(args.length() == 2);
+  DCHECK(args.length() == 3);
   HandleScope scope(isolate);
   CONVERT_ARG_HANDLE_CHECKED(JSObject, promise, 0);
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, function, 1);
+  CONVERT_ARG_HANDLE_CHECKED(Object, handler, 2);
   isolate->PushPromise(promise, function);
+  Debug* debug = isolate->debug();
+  if (handler->IsJSFunction() && DebugStepInIsActive(debug)) {
+    FloodDebugSubjectWithOneShot(debug, Handle<JSFunction>::cast(handler));
+  }
   return isolate->heap()->undefined_value();
 }
 

src/runtime/runtime.h

@@ -201,7 +201,7 @@ namespace internal {
   F(GetScript, 1, 1)                           \
   F(DebugCallbackSupportsStepping, 1, 1)       \
   F(DebugPrepareStepInIfStepping, 1, 1)        \
-  F(DebugPushPromise, 2, 1)                    \
+  F(DebugPushPromise, 3, 1)                    \
   F(DebugPopPromise, 0, 1)                     \
   F(DebugPromiseEvent, 1, 1)                   \
   F(DebugAsyncTaskEvent, 1, 1)                 \

test/mjsunit/es6/debug-promises/stepin-constructor.js

+// 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.
+
+// Flags: --expose-debug-as debug
+
+var Debug = debug.Debug;
+var exception = null;
+var breaks = [];
+
+function listener(event, exec_state, event_data, data) {
+  if (event != Debug.DebugEvent.Break) return;
+  try {
+    breaks.push(exec_state.frame(0).sourceLineText().trimLeft());
+    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+  } catch (e) {
+    exception = e;
+  }
+}
+
+Debug.setListener(listener);
+
+function resolver(resolve, reject) {
+  1;
+  2;
+  3;
+  resolve();
+}
+
+debugger;
+var p = new Promise(resolver);
+
+Debug.setListener(null);
+
+var expected_breaks = [
+  "debugger;",
+  "var p = new Promise(resolver);",
+  "1;",
+  "2;",
+  "3;",
+  "resolve();",
+  "}",
+  "Debug.setListener(null);"
+];
+
+assertEquals(expected_breaks, breaks);
+assertNull(exception);

test/mjsunit/regress/regress-crbug-401915.js

@@ -10,7 +10,7 @@ Debug.setBreakOnException();
 
 try {
   try {
-    %DebugPushPromise(new Promise(function() {}), function() {});
+    %DebugPushPromise(new Promise(function() {}), function() {}, function() {});
   } catch (e) {
   }
   throw new Error();