DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: set ts=8 sts=2 et sw=2 tw=80:
 */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "mozilla/TypeTraits.h"
#include "mozilla/UniquePtr.h"

#include "js/ArrayBuffer.h"  // JS::NewArrayBuffer
#include "js/RootingAPI.h"
#include "jsapi-tests/tests.h"
#include "vm/Runtime.h"

#include "vm/JSContext-inl.h"

// A heap-allocated structure containing one of our barriered pointer wrappers
// to test.
template <typename W>
struct TestStruct {
  W wrapper;
};

// A specialized version for GCPtr that adds a zone() method.
template <typename T>
struct TestStruct<js::GCPtr<T>> {
  js::GCPtr<T> wrapper;

  void trace(JSTracer* trc) {
    TraceNullableEdge(trc, &wrapper, "TestStruct::wrapper");
  }
};

// Give the GCPtr version GCManagedDeletePolicy as required.
namespace JS {
template <typename T>
struct DeletePolicy<TestStruct<js::GCPtr<T>>>
    : public js::GCManagedDeletePolicy<TestStruct<js::GCPtr<T>>> {};
}  // namespace JS

template <typename T>
static T* CreateGCThing(JSContext* cx) {
  MOZ_CRASH();
  return nullptr;
}

template <>
JSObject* CreateGCThing(JSContext* cx) {
  JS::RootedObject obj(cx, JS_NewPlainObject(cx));
  if (!obj) {
    return nullptr;
  }
  JS_DefineProperty(cx, obj, "x", 42, 0);
  return obj;
}

template <>
JSFunction* CreateGCThing(JSContext* cx) {
  /*
   * We don't actually use the function as a function, so here we cheat and
   * cast a JSObject.
   */
  return static_cast<JSFunction*>(CreateGCThing<JSObject>(cx));
}

BEGIN_TEST(testGCHeapPostBarriers) {
#ifdef JS_GC_ZEAL
  AutoLeaveZeal nozeal(cx);
#endif /* JS_GC_ZEAL */

  /* Sanity check - objects start in the nursery and then become tenured. */
  JS_GC(cx);
  JS::RootedObject obj(cx, CreateGCThing<JSObject>(cx));
  CHECK(js::gc::IsInsideNursery(obj.get()));
  JS_GC(cx);
  CHECK(!js::gc::IsInsideNursery(obj.get()));
  JS::RootedObject tenuredObject(cx, obj);

  /* Currently JSObject and JSFunction objects are nursery allocated. */
  CHECK(TestHeapPostBarriersForType<JSObject>());
  CHECK(TestHeapPostBarriersForType<JSFunction>());

  return true;
}

bool CanAccessObject(JSObject* obj) {
  JS::RootedObject rootedObj(cx, obj);
  JS::RootedValue value(cx);
  CHECK(JS_GetProperty(cx, rootedObj, "x", &value));
  CHECK(value.isInt32());
  CHECK(value.toInt32() == 42);
  return true;
}

template <typename T>
bool TestHeapPostBarriersForType() {
  CHECK((TestHeapPostBarriersForWrapper<T, JS::Heap<T*>>()));
  CHECK((TestHeapPostBarriersForWrapper<T, js::GCPtr<T*>>()));
  CHECK((TestHeapPostBarriersForWrapper<T, js::HeapPtr<T*>>()));
  return true;
}

template <typename T, typename W>
bool TestHeapPostBarriersForWrapper() {
  CHECK((TestHeapPostBarrierUpdate<T, W>()));
  CHECK((TestHeapPostBarrierInitFailure<T, W>()));
  return true;
}

template <typename T, typename W>
bool TestHeapPostBarrierUpdate() {
  // Normal case - allocate a heap object, write a nursery pointer into it and
  // check that it gets updated on minor GC.

  T* initialObj = CreateGCThing<T>(cx);
  CHECK(initialObj != nullptr);
  CHECK(js::gc::IsInsideNursery(initialObj));
  uintptr_t initialObjAsInt = uintptr_t(initialObj);

  TestStruct<W>* ptr = nullptr;

  {
    auto testStruct = cx->make_unique<TestStruct<W>>();
    CHECK(testStruct);

    W& wrapper = testStruct->wrapper;
    CHECK(wrapper.get() == nullptr);
    wrapper = initialObj;
    CHECK(wrapper == initialObj);

    ptr = testStruct.release();
  }

  cx->minorGC(JS::GCReason::API);

  W& wrapper = ptr->wrapper;
  CHECK(uintptr_t(wrapper.get()) != initialObjAsInt);
  CHECK(!js::gc::IsInsideNursery(wrapper.get()));
  CHECK(CanAccessObject(wrapper.get()));

  JS::DeletePolicy<TestStruct<W>>()(ptr);

  cx->minorGC(JS::GCReason::API);

  return true;
}

template <typename T, typename W>
bool TestHeapPostBarrierInitFailure() {
  // Failure case - allocate a heap object, write a nursery pointer into it
  // and fail to complete initialization.

  T* initialObj = CreateGCThing<T>(cx);
  CHECK(initialObj != nullptr);
  CHECK(js::gc::IsInsideNursery(initialObj));

  {
    auto testStruct = cx->make_unique<TestStruct<W>>();
    CHECK(testStruct);

    W& wrapper = testStruct->wrapper;
    CHECK(wrapper.get() == nullptr);
    wrapper = initialObj;
    CHECK(wrapper == initialObj);

    // testStruct deleted here, as if we left this block due to an error.
  }

  cx->minorGC(JS::GCReason::API);

  return true;
}

END_TEST(testGCHeapPostBarriers)

BEGIN_TEST(testUnbarrieredEquality) {
#ifdef JS_GC_ZEAL
  AutoLeaveZeal nozeal(cx);
#endif /* JS_GC_ZEAL */

  // Use ArrayBuffers because they have finalizers, which allows using them in
  // TenuredHeap<> without awkward conversations about nursery allocatability.
  JS::RootedObject robj(cx, JS::NewArrayBuffer(cx, 20));
  JS::RootedObject robj2(cx, JS::NewArrayBuffer(cx, 30));
  cx->runtime()->gc.evictNursery();  // Need tenured objects

  // Need some bare pointers to compare against.
  JSObject* obj = robj;
  JSObject* obj2 = robj2;
  const JSObject* constobj = robj;
  const JSObject* constobj2 = robj2;

  // Make them gray. We will make sure they stay gray. (For most reads, the
  // barrier will unmark gray.)
  using namespace js::gc;
  TenuredCell* cell = &obj->asTenured();
  TenuredCell* cell2 = &obj2->asTenured();
  cell->markIfUnmarked(MarkColor::Gray);
  cell2->markIfUnmarked(MarkColor::Gray);
  MOZ_ASSERT(cell->isMarkedGray());
  MOZ_ASSERT(cell2->isMarkedGray());

  {
    JS::Heap<JSObject*> heap(obj);
    JS::Heap<JSObject*> heap2(obj2);
    CHECK(TestWrapper(obj, obj2, heap, heap2));
    CHECK(TestWrapper(constobj, constobj2, heap, heap2));
  }

  {
    JS::TenuredHeap<JSObject*> heap(obj);
    JS::TenuredHeap<JSObject*> heap2(obj2);
    CHECK(TestWrapper(obj, obj2, heap, heap2));
    CHECK(TestWrapper(constobj, constobj2, heap, heap2));
  }

  // Sanity check that the barriers normally mark things black.
  {
    JS::Heap<JSObject*> heap(obj);
    JS::Heap<JSObject*> heap2(obj2);
    heap.get();
    heap2.get();
    CHECK(cell->isMarkedBlack());
    CHECK(cell2->isMarkedBlack());
  }

  return true;
}

template <typename ObjectT, typename WrapperT>
bool TestWrapper(ObjectT obj, ObjectT obj2, WrapperT& wrapper,
                 WrapperT& wrapper2) {
  using namespace js::gc;

  const TenuredCell& cell = obj->asTenured();
  const TenuredCell& cell2 = obj2->asTenured();

  int x = 0;

  CHECK(cell.isMarkedGray());
  CHECK(cell2.isMarkedGray());
  x += obj == obj2;
  CHECK(cell.isMarkedGray());
  CHECK(cell2.isMarkedGray());
  x += obj == wrapper2;
  CHECK(cell.isMarkedGray());
  CHECK(cell2.isMarkedGray());
  x += wrapper == obj2;
  CHECK(cell.isMarkedGray());
  CHECK(cell2.isMarkedGray());
  x += wrapper == wrapper2;
  CHECK(cell.isMarkedGray());
  CHECK(cell2.isMarkedGray());

  CHECK(x == 0);

  x += obj != obj2;
  CHECK(cell.isMarkedGray());
  CHECK(cell2.isMarkedGray());
  x += obj != wrapper2;
  CHECK(cell.isMarkedGray());
  CHECK(cell2.isMarkedGray());
  x += wrapper != obj2;
  CHECK(cell.isMarkedGray());
  CHECK(cell2.isMarkedGray());
  x += wrapper != wrapper2;
  CHECK(cell.isMarkedGray());
  CHECK(cell2.isMarkedGray());

  CHECK(x == 4);

  return true;
}

END_TEST(testUnbarrieredEquality)