Add test and mitigation for clang 11 compiler bug (#27073)

* Add test and mitigation for clang 11 compiler bug

* document

* document

* Automated change: Fix sanity tests

Co-authored-by: ctiller <ctiller@users.noreply.github.com>

CMakeLists.txt

@@ -910,6 +910,7 @@ if(gRPC_BUILD_TESTS)
   add_dependencies(buildtests_cxx match_test)
   add_dependencies(buildtests_cxx matchers_test)
   add_dependencies(buildtests_cxx message_allocator_end2end_test)
+  add_dependencies(buildtests_cxx miscompile_with_no_unique_address_test)
   add_dependencies(buildtests_cxx mock_stream_test)
   add_dependencies(buildtests_cxx mock_test)
   add_dependencies(buildtests_cxx nonblocking_test)
@@ -12705,6 +12706,40 @@ target_link_libraries(message_allocator_end2end_test
 )
 
 
+endif()
+if(gRPC_BUILD_TESTS)
+
+add_executable(miscompile_with_no_unique_address_test
+  test/core/compiler_bugs/miscompile_with_no_unique_address_test.cc
+  third_party/googletest/googletest/src/gtest-all.cc
+  third_party/googletest/googlemock/src/gmock-all.cc
+)
+
+target_include_directories(miscompile_with_no_unique_address_test
+  PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}
+    ${CMAKE_CURRENT_SOURCE_DIR}/include
+    ${_gRPC_ADDRESS_SORTING_INCLUDE_DIR}
+    ${_gRPC_RE2_INCLUDE_DIR}
+    ${_gRPC_SSL_INCLUDE_DIR}
+    ${_gRPC_UPB_GENERATED_DIR}
+    ${_gRPC_UPB_GRPC_GENERATED_DIR}
+    ${_gRPC_UPB_INCLUDE_DIR}
+    ${_gRPC_XXHASH_INCLUDE_DIR}
+    ${_gRPC_ZLIB_INCLUDE_DIR}
+    third_party/googletest/googletest/include
+    third_party/googletest/googletest
+    third_party/googletest/googlemock/include
+    third_party/googletest/googlemock
+    ${_gRPC_PROTO_GENS_DIR}
+)
+
+target_link_libraries(miscompile_with_no_unique_address_test
+  ${_gRPC_PROTOBUF_LIBRARIES}
+  ${_gRPC_ALLTARGETS_LIBRARIES}
+)
+
+
 endif()
 if(gRPC_BUILD_TESTS)
 

build_autogenerated.yaml

@@ -5955,6 +5955,15 @@ targets:
   - test/cpp/end2end/test_service_impl.cc
   deps:
   - grpc++_test_util
+- name: miscompile_with_no_unique_address_test
+  gtest: true
+  build: test
+  language: c++
+  headers: []
+  src:
+  - test/core/compiler_bugs/miscompile_with_no_unique_address_test.cc
+  deps: []
+  uses_polling: false
 - name: mock_stream_test
   gtest: true
   build: test

include/grpc/impl/codegen/port_platform.h

@@ -684,4 +684,15 @@ typedef unsigned __int64 uint64_t;
 
 #define GRPC_CALLBACK_API_NONEXPERIMENTAL
 
+/* clang 11 with msan miscompiles destruction of [[no_unique_address]] members
+ * of zero size - for a repro see:
+ * test/core/compiler_bugs/miscompile_with_no_unique_address_test.cc
+ */
+#ifdef __clang__
+#if __clang__ && __clang_major__ <= 11 && __has_feature(memory_sanitizer)
+#undef GPR_NO_UNIQUE_ADDRESS
+#define GPR_NO_UNIQUE_ADDRESS
+#endif
+#endif
+
 #endif /* GRPC_IMPL_CODEGEN_PORT_PLATFORM_H */

test/core/compiler_bugs/BUILD

@@ -0,0 +1,31 @@
+# Copyright 2021 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+load("//bazel:grpc_build_system.bzl", "grpc_cc_test", "grpc_package")
+
+licenses(["notice"])
+
+grpc_package(name = "test/core/compiler_bugs")
+
+grpc_cc_test(
+    name = "miscompile_with_no_unique_address_test",
+    srcs = ["miscompile_with_no_unique_address_test.cc"],
+    external_deps = ["gtest"],
+    language = "c++",
+    uses_polling = False,
+    deps = [
+        "//:gpr_platform",
+        "//test/core/util:grpc_suppressions",
+    ],
+)

test/core/compiler_bugs/miscompile_with_no_unique_address_test.cc

@@ -0,0 +1,58 @@
+// Copyright 2021 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <grpc/impl/codegen/port_platform.h>
+#include <gtest/gtest.h>
+
+// Make a template argument to test which bit pattern remains in A's destructor
+// to try and detect similar bugs in non-MSAN builds (none have been detected
+// yet thankfully)
+template <int kInit>
+class A {
+ public:
+  ~A() { EXPECT_EQ(a_, kInit); }
+  int a_ = kInit;
+};
+template <class T, int kInit>
+class P : A<kInit> {
+ public:
+  explicit P(T b) : b_(b) {}
+  // clang 11 with MSAN miscompiles this and marks A::a_ as uninitialized during
+  // P::~P() if GPR_NO_UNIQUE_ADDRESS is [[no_unique_address]] - so this test
+  // stands to ensure that we have a working definition for this compiler so
+  // that we don't flag false negatives elsewhere in the codebase.
+  GPR_NO_UNIQUE_ADDRESS T b_;
+};
+
+template <int kInit, class T>
+void c(T a) {
+  P<T, kInit> _(a);
+}
+
+TEST(Miscompile, Zero) {
+  c<0>([] {});
+}
+
+TEST(Miscompile, One) {
+  c<1>([] {});
+}
+
+TEST(Miscompile, MinusOne) {
+  c<-1>([] {});
+}
+
+int main(int argc, char** argv) {
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}

tools/run_tests/generated/tests.json

@@ -5513,6 +5513,30 @@
     ],
     "uses_polling": true
   },
+  {
+    "args": [],
+    "benchmark": false,
+    "ci_platforms": [
+      "linux",
+      "mac",
+      "posix",
+      "windows"
+    ],
+    "cpu_cost": 1.0,
+    "exclude_configs": [],
+    "exclude_iomgrs": [],
+    "flaky": false,
+    "gtest": true,
+    "language": "c++",
+    "name": "miscompile_with_no_unique_address_test",
+    "platforms": [
+      "linux",
+      "mac",
+      "posix",
+      "windows"
+    ],
+    "uses_polling": false
+  },
   {
     "args": [],
     "benchmark": false,