https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106665
Bug ID: 106665
Summary: Cannot pass barrier by reference
Product: gcc
Version: 12.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: shihyente at hotmail dot com
Target Milestone: ---
Hi,
The failed case was tested under Ubuntu 22.04.1 LTS
g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/home/yt/Utils/gcc-12.2.0-RC-20220812/libexec/gcc/x86_64-pc-linux-gnu/12.1.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../configure --prefix=/home/yt/Utils/gcc-12.2.0-RC-20220812
--enable-languages=c,c++ --enable-libstdcxx-backtrace=yes --disable-multilib
--enable-checking=yes
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 12.1.1 20220812 (GCC)
Code (test.cpp)
#include <vector>
#include <thread>
#include <barrier>
using namespace std;
void foo(auto& sync_point) {
sync_point.arrive_and_wait();
}
int main() {
vector<jthread> pool;
barrier sync_point(8);
for (size_t i = 0; i < 8; ++i)
pool.emplace_back([&] { foo(sync_point); });
}
Commandline to compile (no warning):
/home/yt/Utils/gcc-12.2.0-RC-20220812/bin/g++ -std=c++23 -g -O0 -Wall -Wextra
-fno-strict-aliasing -fwrapv -fno-aggressive-loop-optimizations
-fsanitize=undefined -pthread
-Wl,-rpath=/home/yt/Utils/gcc-12.2.0-RC-20220812/lib64 test.cpp
Run (sometimes only showed "Segmentation fault (core dumped)")
/home/yt/Utils/gcc-12.2.0-RC-20220812/include/c++/12.1.1/bits/unique_ptr.h:720:14:
runtime error: reference binding to null pointer of type 'struct __state_t'
/home/yt/Utils/gcc-12.2.0-RC-20220812/include/c++/12.1.1/barrier:120:8: runtime
error: member access within null pointer of type 'struct __state_t'
/home/yt/Utils/gcc-12.2.0-RC-20220812/include/c++/12.1.1/barrier:120:17:
runtime error: member call on null pointer of type 'struct __tickets_t'
/home/yt/Utils/gcc-12.2.0-RC-20220812/include/c++/12.1.1/array:209:26: runtime
error: member access within null pointer of type 'struct array'
/home/yt/Utils/gcc-12.2.0-RC-20220812/include/c++/12.1.1/array:209:26: runtime
error: reference binding to null pointer of type 'const __barrier_phase_t'
/home/yt/Utils/gcc-12.2.0-RC-20220812/include/c++/12.1.1/array:61:41: runtime
error: load of null pointer of type 'const __barrier_phase_t'
/home/yt/Utils/gcc-12.2.0-RC-20220812/include/c++/12.1.1/array:61:41: runtime
error: reference binding to null pointer of type '__barrier_phase_t'
/home/yt/Utils/gcc-12.2.0-RC-20220812/include/c++/12.1.1/array:61:41: runtime
error: load of null pointer of type 'const __barrier_phase_t'
/home/yt/Utils/gcc-12.2.0-RC-20220812/include/c++/12.1.1/array:209:39: runtime
error: reference binding to null pointer of type 'value_type'
/home/yt/Utils/gcc-12.2.0-RC-20220812/include/c++/12.1.1/barrier:119:24:
runtime error: reference binding to null pointer of type '__barrier_phase_t'
Segmentation fault (core dumped)
GDB (sometimes only showed "exited normally")
Thread 9 "a.out" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff3c09640 (LWP 374398)]
0x000000000040a5bb in
std::__atomic_impl::compare_exchange_strong<std::__barrier_phase_t>
(__failure=std::memory_order::acquire, __success=std::memory_order::acq_rel,
__desired=(unknown: 0x1), __expected=@0x7ffff3c08baf: 0, __ptr=0xc0) at
/home/yt/Utils/gcc-12.2.0-RC-20220812/include/c++/12.1.1/bits/atomic_base.h:1005
1005 return __atomic_compare_exchange(__ptr,
std::__addressof(__expected),
Known workaround: Do not pass barrier by reference.
MSVC and Clang++ are working fine, so I am assuming the test code is legal.
Thank you very much.
Best,
John Shih
