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* [Bug c++/101027] New: Short-circuit behavior not respected with co_await in while head @ 2021-06-11 9:02 alois1@gmx-topmail.de 2021-11-30 20:50 ` [Bug c++/101027] " kiwixz at outlook dot com ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: alois1@gmx-topmail.de @ 2021-06-11 9:02 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101027 Bug ID: 101027 Summary: Short-circuit behavior not respected with co_await in while head Product: gcc Version: 11.1.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: alois1@gmx-topmail.de Target Milestone: --- Created attachment 50983 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50983&action=edit Reduced preprocessed code GCC miscompiles the following C++ program: $ cat test.cpp #include <coroutine> struct task { struct promise_type { task get_return_object() { return {std::coroutine_handle<promise_type>::from_promise(*this)}; } std::suspend_never initial_suspend() { return {}; } std::suspend_never final_suspend() noexcept { return {}; } void unhandled_exception() {} void return_void() {} }; bool await_ready() { return true; } void await_suspend(std::coroutine_handle<>) {} bool await_resume() { return true; } std::coroutine_handle<promise_type> m_handle; }; extern "C" void exit(int status); task should_not_execute() { exit(1); co_return; } task main_task() { while (false && co_await should_not_execute()); } int main() { main_task(); } $ gcc -v Using built-in specs. COLLECT_GCC=/usr/bin/gcc COLLECT_LTO_WRAPPER=/usr/lib64/gcc/x86_64-suse-linux/11/lto-wrapper OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa OFFLOAD_TARGET_DEFAULT=1 Target: x86_64-suse-linux Configured with: ../configure --prefix=/usr --infodir=/usr/share/info --mandir=/usr/share/man --libdir=/usr/lib64 --libexecdir=/usr/lib64 --enable-languages=c,c++,objc,fortran,obj-c++,ada,go,d,jit --enable-offload-targets=nvptx-none,amdgcn-amdhsa, --without-cuda-driver --enable-host-shared --enable-checking=release --disable-werror --with-gxx-include-dir=/usr/include/c++/11 --enable-ssp --disable-libssp --disable-libvtv --enable-cet=auto --disable-libcc1 --enable-plugin --with-bugurl=https://bugs.opensuse.org/ --with-pkgversion='SUSE Linux' --with-slibdir=/lib64 --with-system-zlib --enable-libstdcxx-allocator=new --disable-libstdcxx-pch --enable-libphobos --enable-version-specific-runtime-libs --with-gcc-major-version-only --enable-linker-build-id --enable-linux-futex --enable-gnu-indirect-function --program-suffix=-11 --without-system-libunwind --enable-multilib --with-arch-32=x86-64 --with-tune=generic --with-build-config=bootstrap-lto-lean --enable-link-mutex --build=x86_64-suse-linux --host=x86_64-suse-linux Thread model: posix Supported LTO compression algorithms: zlib zstd gcc version 11.1.1 20210510 [revision 23855a176609fe8dda6abaf2b21846b4517966eb] (SUSE Linux) $ g++ -std=c++20 test.cpp; ./a.out; echo $? 1 Expected output would be 0, as the && operator should short-circuit, and should_not_execute therefore should never be started (in particular, the call to exit should not be reached). Interestingly, the unexpected behavior only happens in a while head, in an if head or assignment to a variable the short-circuit behavior seems to be respected. For convenience, I have attached a manually reduced version of the preprocessed code that I have confirmed to exhibit the same behavior. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/101027] Short-circuit behavior not respected with co_await in while head 2021-06-11 9:02 [Bug c++/101027] New: Short-circuit behavior not respected with co_await in while head alois1@gmx-topmail.de @ 2021-11-30 20:50 ` kiwixz at outlook dot com 2023-08-02 15:10 ` sichert at in dot tum.de ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: kiwixz at outlook dot com @ 2021-11-30 20:50 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101027 kiwixz at outlook dot com changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |kiwixz at outlook dot com --- Comment #1 from kiwixz at outlook dot com --- Hello, I encountered the same problem with gcc evaluating the two asio coroutine operands of && even when the left one returned false. See on godbolt: https://godbolt.org/z/Wo8z5PoP3 Expected output (confirmed on clang 12 with libc++): a 0 GCC 11.2 or trunk: a b 0 --- #include <iostream> #include <boost/asio.hpp> namespace asio = boost::asio; asio::awaitable<bool> a() { std::cout << "a\n"; co_return false; } asio::awaitable<bool> b() { std::cout << "b\n"; co_return false; } asio::awaitable<void> f() { std::cout << ((co_await a()) && (co_await b())) << "\n"; } int main() { asio::io_context io; asio::co_spawn(io, f, asio::detached); io.run(); } ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/101027] Short-circuit behavior not respected with co_await in while head 2021-06-11 9:02 [Bug c++/101027] New: Short-circuit behavior not respected with co_await in while head alois1@gmx-topmail.de 2021-11-30 20:50 ` [Bug c++/101027] " kiwixz at outlook dot com @ 2023-08-02 15:10 ` sichert at in dot tum.de 2023-11-03 19:04 ` pinskia at gcc dot gnu.org 2023-11-03 19:04 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: sichert at in dot tum.de @ 2023-08-02 15:10 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101027 Moritz Sichert <sichert at in dot tum.de> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |sichert at in dot tum.de --- Comment #2 from Moritz Sichert <sichert at in dot tum.de> --- Created attachment 55677 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55677&action=edit Coroutine that segfaults because it does not short-circuit I have encountered the same problem where co_await in a logical operation does not short-circuit correctly. See the attached example. The code segfaults because in the condition "foo && co_await foo->foo(123)" it starts executing the coroutine even if foo is nullptr. For some reason the error only occurs if the condition is nested in a logical-|| expression. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/101027] Short-circuit behavior not respected with co_await in while head 2021-06-11 9:02 [Bug c++/101027] New: Short-circuit behavior not respected with co_await in while head alois1@gmx-topmail.de 2021-11-30 20:50 ` [Bug c++/101027] " kiwixz at outlook dot com 2023-08-02 15:10 ` sichert at in dot tum.de @ 2023-11-03 19:04 ` pinskia at gcc dot gnu.org 2023-11-03 19:04 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-11-03 19:04 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101027 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |oremanj at mit dot edu --- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- *** Bug 112360 has been marked as a duplicate of this bug. *** ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/101027] Short-circuit behavior not respected with co_await in while head 2021-06-11 9:02 [Bug c++/101027] New: Short-circuit behavior not respected with co_await in while head alois1@gmx-topmail.de ` (2 preceding siblings ...) 2023-11-03 19:04 ` pinskia at gcc dot gnu.org @ 2023-11-03 19:04 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-11-03 19:04 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101027 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2023-11-03 Ever confirmed|0 |1 --- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Confirmed. ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2023-11-03 19:04 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-06-11 9:02 [Bug c++/101027] New: Short-circuit behavior not respected with co_await in while head alois1@gmx-topmail.de 2021-11-30 20:50 ` [Bug c++/101027] " kiwixz at outlook dot com 2023-08-02 15:10 ` sichert at in dot tum.de 2023-11-03 19:04 ` pinskia at gcc dot gnu.org 2023-11-03 19:04 ` pinskia at gcc dot gnu.org
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