cppgc: Add simple check/dcheck facilities

A few notes:
1) Oilpan is a generic library, meaning that it can work with arbitrary
user types. The library is split in type-aware (include/) and
type-erased (src/) parts. The former comprises a lot of code that still
needs to be defended with dchecks;
2) Macros are prefixed with CPPGC_, so that they don't clash in the user
code with similar macros from other libraries;
3) The macros simply forward requests to V8 so that dcheck handlers can
be configured uniformly;
4) The CL doesn't contain CHECK_EQ and friends, but they can be added
later if needed.

Bug: chromium:1056170
Change-Id: I68e6f663247705233eaf030384164d81e53071e1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2148774
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67129}

BUILD.gn

@@ -3979,6 +3979,7 @@ v8_source_set("cppgc_base") {
     "src/heap/cppgc/heap.cc",
     "src/heap/cppgc/heap.h",
     "src/heap/cppgc/liveness-broker.cc",
+    "src/heap/cppgc/logging.cc",
     "src/heap/cppgc/page-memory-inl.h",
     "src/heap/cppgc/page-memory.cc",
     "src/heap/cppgc/page-memory.h",

include/cppgc/internal/logging.h

@@ -0,0 +1,50 @@
+// Copyright 2020 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.
+
+#ifndef INCLUDE_CPPGC_INTERNAL_LOGGING_H_
+#define INCLUDE_CPPGC_INTERNAL_LOGGING_H_
+
+#include "include/cppgc/source-location.h"
+#include "include/v8config.h"
+
+namespace cppgc {
+namespace internal {
+
+void V8_EXPORT DCheckImpl(const char*,
+                          const SourceLocation& = SourceLocation::Current());
+[[noreturn]] void V8_EXPORT
+FatalImpl(const char*, const SourceLocation& = SourceLocation::Current());
+
+// Used to ignore -Wunused-variable.
+template <typename>
+struct EatParams {};
+
+#if DEBUG
+#define CPPGC_DCHECK_MSG(condition, message)  \
+  do {                                        \
+    if (V8_UNLIKELY(!(condition))) {          \
+      ::cppgc::internal::DCheckImpl(message); \
+    }                                         \
+  } while (false)
+#else
+#define CPPGC_DCHECK_MSG(condition, message)                \
+  (static_cast<void>(::cppgc::internal::EatParams<decltype( \
+                         static_cast<void>(condition), message)>{}))
+#endif
+
+#define CPPGC_DCHECK(condition) CPPGC_DCHECK_MSG(condition, #condition)
+
+#define CPPGC_CHECK_MSG(condition, message)  \
+  do {                                       \
+    if (V8_UNLIKELY(!(condition))) {         \
+      ::cppgc::internal::FatalImpl(message); \
+    }                                        \
+  } while (false)
+
+#define CPPGC_CHECK(condition) CPPGC_CHECK_MSG(condition, #condition)
+
+}  // namespace internal
+}  // namespace cppgc
+
+#endif  // INCLUDE_CPPGC_INTERNAL_LOGGING_H_

include/cppgc/visitor.h

@@ -6,6 +6,7 @@
 #define INCLUDE_CPPGC_VISITOR_H_
 
 #include "include/cppgc/garbage-collected.h"
+#include "include/cppgc/internal/logging.h"
 #include "include/cppgc/internal/pointer-policies.h"
 #include "include/cppgc/liveness-broker.h"
 #include "include/cppgc/member.h"
@@ -29,8 +30,7 @@ class Visitor {
   template <typename T>
   void Trace(const Member<T>& member) {
     const T* value = member.GetRawAtomic();
-    // TODO(chromium:1056170): DCHECK (or similar) for deleted values as they
-    // should come in at a different path.
+    CPPGC_DCHECK(value != kSentinelPointer);
     Trace(value);
   }
 

src/heap/cppgc/logging.cc

@@ -0,0 +1,29 @@
+// Copyright 2020 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 "include/cppgc/internal/logging.h"
+#include "include/cppgc/source-location.h"
+
+#include "src/base/logging.h"
+
+namespace cppgc {
+namespace internal {
+
+void DCheckImpl(const char* message, const SourceLocation& loc) {
+  V8_Dcheck(loc.FileName(), static_cast<int>(loc.Line()), message);
+}
+
+void FatalImpl(const char* message, const SourceLocation& loc) {
+#if DEBUG
+  V8_Fatal(loc.FileName(), static_cast<int>(loc.Line()), "Check failed: %s.",
+           message);
+#elif !defined(OFFICIAL_BUILD)
+  V8_Fatal("Check failed: %s.", message);
+#else
+  V8_Fatal("ignored");
+#endif
+}
+
+}  // namespace internal
+}  // namespace cppgc

test/unittests/BUILD.gn

@@ -50,6 +50,7 @@ v8_source_set("cppgc_unittests_sources") {
     "heap/cppgc/heap-object-header_unittest.cc",
     "heap/cppgc/heap-page_unittest.cc",
     "heap/cppgc/heap_unittest.cc",
+    "heap/cppgc/logging_unittest.cc",
     "heap/cppgc/member_unittests.cc",
     "heap/cppgc/page-memory_unittest.cc",
     "heap/cppgc/prefinalizer_unittests.cc",

test/unittests/heap/cppgc/logging_unittest.cc

@@ -0,0 +1,79 @@
+// Copyright 2020 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 <string>
+
+#include "include/cppgc/internal/logging.h"
+#include "include/cppgc/source-location.h"
+
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace cppgc {
+namespace internal {
+
+namespace {
+// GCC < 9 has a bug due to which calling non-constexpr functions are not
+// allowed even on constexpr path:
+// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67026.
+#if !defined(__GNUC__) || defined(__clang__)
+constexpr int CheckInConstexpr(int a) {
+  CPPGC_DCHECK(a > 0);
+  CPPGC_CHECK(a > 0);
+  return a;
+}
+#endif
+}  // namespace
+
+TEST(LoggingTest, Pass) {
+  CPPGC_DCHECK(true);
+  CPPGC_CHECK(true);
+}
+
+TEST(LoggingTest, Fail) {
+#if DEBUG
+  EXPECT_DEATH_IF_SUPPORTED(CPPGC_DCHECK(false), "");
+#endif
+  EXPECT_DEATH_IF_SUPPORTED(CPPGC_CHECK(false), "");
+}
+
+TEST(LoggingTest, DontReportUnused) {
+  int a = 1;
+  CPPGC_DCHECK(a);
+}
+
+#if !defined(__GNUC__) || defined(__clang__)
+TEST(LoggingTest, ConstexprContext) {
+  constexpr int a = CheckInConstexpr(1);
+  CPPGC_DCHECK(a);
+}
+#endif
+
+#if DEBUG && !defined(OFFICIAL_BUILD)
+TEST(LoggingTest, Message) {
+  using ::testing::ContainsRegex;
+  EXPECT_DEATH_IF_SUPPORTED(CPPGC_DCHECK(5 == 7),
+                            ContainsRegex("failed.*5 == 7"));
+  EXPECT_DEATH_IF_SUPPORTED(CPPGC_CHECK(5 == 7),
+                            ContainsRegex("failed.*5 == 7"));
+}
+
+#if CPPGC_SUPPORTS_SOURCE_LOCATION
+TEST(LoggingTest, SourceLocation) {
+  using ::testing::AllOf;
+  using ::testing::HasSubstr;
+  constexpr auto loc = SourceLocation::Current();
+  EXPECT_DEATH_IF_SUPPORTED(CPPGC_DCHECK(false),
+                            AllOf(HasSubstr(loc.FileName()),
+                                  HasSubstr(std::to_string(loc.Line() + 3))));
+  EXPECT_DEATH_IF_SUPPORTED(CPPGC_CHECK(false),
+                            AllOf(HasSubstr(loc.FileName()),
+                                  HasSubstr(std::to_string(loc.Line() + 6))));
+}
+#endif  // CPPGC_SUPPORTS_SOURCE_LOCATION
+
+#endif  // DEBUG
+
+}  // namespace internal
+}  // namespace cppgc