【发布时间】：2016-09-24 06:53:35
【问题描述】：
我有一个看起来像这样的函数 -
std::string func()
{
std::string result;
...
auto seed = std::random_device()();
std::mt19937 gen(seed);
std::uniform_int_distribution<> dis(0, 61);
...
return result;
}
它可以在各种编译器及其版本中正常编译，但仍然无法通过 Ubuntu 上的 valgrind 测试。我明确提到了 ubuntu，因为它在我安装了 Arch Linux 的机器上成功通过。
两个 valgrind 安装都报告它们的版本为 valgrind-3.11.0，唯一的区别是 Arch Linux 安装在我的机器上，没有虚拟化，而 Ubuntu 测试已经在 DO/CI 服务器上完成，可能处于某种虚拟化状态。但这有关系吗？
这是 valgrind 运行的日志 -
--- stderr ---
==13849== Memcheck, a memory error detector
==13849== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==13849== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==13849== Command: file/path/here
==13849==
vex amd64->IR: unhandled instruction bytes: 0xF 0xC7 0xF0 0x89 0x6 0xF 0x42 0xC1
vex amd64->IR: REX=0 REX.W=0 REX.R=0 REX.X=0 REX.B=0
vex amd64->IR: VEX=0 VEX.L=0 VEX.nVVVV=0x0 ESC=0F
vex amd64->IR: PFX.66=0 PFX.F2=0 PFX.F3=0
==13849== valgrind: Unrecognised instruction at address 0x5111715.
==13849== at 0x5111715: ??? (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.22)
==13849== by 0x51118B1: std::random_device::_M_getval() (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.22)
==13849== by 0x4809FB: std::random_device::operator()() (random.h:1612)
==13849== by 0x47F0C2: isaac::deviceList::genId[abi:cxx11](unsigned int) (deviceList.cpp:21)
==13849== by 0x47F2A7: isaac::deviceList::place(isaac::deviceType, nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator>) (deviceList.cpp:38)
==13849== by 0x40D06E: DeviceList_place_Test::TestBody() (test.cpp:194)
==13849== by 0x45D5A7: void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) (gtest.cc:2078)
==13849== by 0x4588D2: void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) (gtest.cc:2114)
==13849== by 0x43EBB3: testing::Test::Run() (gtest.cc:2151)
==13849== by 0x43F3F5: testing::TestInfo::Run() (gtest.cc:2326)
==13849== by 0x43FA52: testing::TestCase::Run() (gtest.cc:2444)
==13849== by 0x446911: testing::internal::UnitTestImpl::RunAllTests() (gtest.cc:4315)
==13849== Your program just tried to execute an instruction that Valgrind
==13849== did not recognise. There are two possible reasons for this.
==13849== 1. Your program has a bug and erroneously jumped to a non-code
==13849== location. If you are running Memcheck and you just saw a
==13849== warning about a bad jump, it's probably your program's fault.
==13849== 2. The instruction is legitimate but Valgrind doesn't handle it,
==13849== i.e. it's Valgrind's fault. If you think this is the case or
==13849== you are not sure, please let us know and we'll try to fix it.
==13849== Either way, Valgrind will now raise a SIGILL signal which will
==13849== probably kill your program.
==13849==
==13849== Process terminating with default action of signal 4 (SIGILL): dumping core
==13849== Illegal opcode at address 0x5111715
==13849== at 0x5111715: ??? (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.22)
==13849== by 0x51118B1: std::random_device::_M_getval() (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.22)
==13849== by 0x4809FB: std::random_device::operator()() (random.h:1612)
==13849== by 0x47F0C2: isaac::deviceList::genId[abi:cxx11](unsigned int) (deviceList.cpp:21)
==13849== by 0x47F2A7: isaac::deviceList::place(isaac::deviceType, nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator>) (deviceList.cpp:38)
==13849== by 0x40D06E: DeviceList_place_Test::TestBody() (test.cpp:194)
==13849== by 0x45D5A7: void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) (gtest.cc:2078)
==13849== by 0x4588D2: void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) (gtest.cc:2114)
==13849== by 0x43EBB3: testing::Test::Run() (gtest.cc:2151)
==13849== by 0x43F3F5: testing::TestInfo::Run() (gtest.cc:2326)
==13849== by 0x43FA52: testing::TestCase::Run() (gtest.cc:2444)
==13849== by 0x446911: testing::internal::UnitTestImpl::RunAllTests() (gtest.cc:4315)
==13849==
==13849== HEAP SUMMARY:
==13849== in use at exit: 84,300 bytes in 108 blocks
==13849== total heap usage: 622 allocs, 514 frees, 530,112 bytes allocated
==13849==
==13849== LEAK SUMMARY:
==13849== definitely lost: 0 bytes in 0 blocks
==13849== indirectly lost: 0 bytes in 0 blocks
==13849== possibly lost: 0 bytes in 0 blocks
==13849== still reachable: 84,300 bytes in 108 blocks
==13849== suppressed: 0 bytes in 0 blocks
==13849== Rerun with --leak-check=full to see details of leaked memory
==13849==
==13849== For counts of detected and suppressed errors, rerun with: -v
==13849== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
-------
编辑 - 我也尝试从官方来源手动构建 valgrind 并安装它，但仍然产生相同的错误。
【问题讨论】：
-
你在 Ubuntu 机器上使用了哪些编译器标志？显然，编译器正在生成一条非法指令。 Ubuntu机器上
/proc/cpuinfo的输出是什么？ -
@MartinNyolt 两个版本都有相同的标志，ubuntu
/proc/cpuinfo- gist.github.com/agauniyal/c8d57b106097a16296b259b86fc93368 -
但是 what 到底是什么标志？我正在帮助您找出为什么您的编译器会生成非法指令。您是否调试了代码并检查了它尝试执行的 哪个 指令？错误是仅在 valgrind 期间发生，还是在正常执行期间也会出现 SIGILL？
-
@MartinNyolt 该错误不会在该程序的编译或执行期间出现，仅在 valgrind 执行期间出现。这是我的构建系统传递的所有标志 -
"c++ '-Ibenchmark/randIdGen@exe' '-fdiagnostics-color=always' '-I../benchmark' '-Ibenchmark' '-pipe' '-Wall' '-Wpedantic' '-Wextra' '-Winvalid-pch' '-Wnon-virtual-dtor' '-std=c++14' '-O0' '-g' '-MMD' '-MQ' 'benchmark/randIdGen@exe/randomIdGen.cpp.o' '-MF' 'benchmark/randIdGen@exe/randomIdGen.cpp.o.d' -o 'benchmark/randIdGen@exe/randomIdGen.cpp.o' -c ../benchmark/randomIdGen.cpp" -
@MartinNyolt “您是否调试了代码并检查了它尝试执行的哪个指令？” Valgrind 是一个调试器，是的，指令已经在问题中了：“
vex amd64->IR: unhandled instruction bytes: 0xF 0xC7 0xF0 0x89 0x6 0xF 0x42 0xC1”
标签： c++ c++11 random memory-leaks valgrind