Your message dated Wed, 27 May 2020 19:16:27 +0000 with message-id <[email protected]> and subject line Bug#916837: Removed package(s) from unstable has caused the Debian Bug report #907649, regarding clang-6.0: Erroneous loop optimisation with -O2, accessing to wrong std::vector element to be marked as done.
This means that you claim that the problem has been dealt with. If this is not the case it is now your responsibility to reopen the Bug report if necessary, and/or fix the problem forthwith. (NB: If you are a system administrator and have no idea what this message is talking about, this may indicate a serious mail system misconfiguration somewhere. Please contact [email protected] immediately.) -- 907649: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=907649 Debian Bug Tracking System Contact [email protected] with problems
--- Begin Message ---Package: clang-6.0 Version: 1:6.0.1-5 Severity: normal Dear Maintainer, When compiling with -O2 the code below, resulting loop is wrongly optimized leading to plainly wrong results (not an approximation), it seems that elements in std::vector are not accessed in the right order. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% #include <iostream> #include <vector> class Foo { private: std::vector<double> _a; std::vector<double> _d; public: Foo(const std::vector<double> &x, const std::vector<double> &y) : _a(x.size()), _d(x.size()) { for (unsigned int i = 0; i < x.size() - 1; i++) { _a[i] = x[i + 1] - x[i]; _d[i] = (y[i + 1] - y[i]) / _a[i]; } } const std::vector<double> &a() const noexcept { return _a; } }; int main() { // Read input file std::vector<double> x, y; while (std::cin) { double xi, yi; if (std::cin >> xi >> yi) { x.push_back(xi); y.push_back(yi); } } // Create Foo instance Foo foo(x, y); // Print computed data for (auto a : foo.a()) std::cout << a << '\n'; return 0; } %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% When executing the following commands (assuming that file bug.cpp contains code above) $> clang++-6.0 -std=c++11 -O2 -o bug bug.cpp $> paste <(seq 1 5) <(seq 1 5) | ./bug the expected result is: 1 1 1 1 0 But one gets: 1 2 2 0 0 Nevertheless, the expected result is obtained with -O1. Best regards, Juan -- System Information: Debian Release: buster/sid APT prefers testing APT policy: (990, 'testing'), (500, 'stable-updates'), (500, 'unstable'), (500, 'stable'), (500, 'oldstable') Architecture: amd64 (x86_64) Kernel: Linux 4.17.0-3-amd64 (SMP w/4 CPU cores) Locale: LANG=en_GB.utf8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE=en_GB:en (charmap=UTF-8) Shell: /bin/sh linked to /bin/dash Init: systemd (via /run/systemd/system) LSM: AppArmor: enabled Versions of packages clang-6.0 depends on: ii binutils 2.31.1-4 ii libc6 2.27-5 ii libc6-dev 2.27-5 ii libclang-common-6.0-dev 1:6.0.1-5 ii libclang1-6.0 1:6.0.1-5 ii libgcc-8-dev 8.2.0-4 ii libgcc1 1:8.2.0-4 ii libjsoncpp1 1.7.4-3 ii libllvm6.0 1:6.0.1-5 ii libobjc-8-dev 8.2.0-4 ii libstdc++-8-dev 8.2.0-4 ii libstdc++6 8.2.0-4 Versions of packages clang-6.0 recommends: ii libomp-dev 6.0.1-1 ii llvm-6.0-dev 1:6.0.1-5 ii python 2.7.15-3 Versions of packages clang-6.0 suggests: pn clang-6.0-doc <none> pn gnustep <none> pn gnustep-devel <none> -- no debconf information
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--- Begin Message ---Version: 1:6.0.1-14.1+rm Dear submitter, as the package llvm-toolchain-6.0 has just been removed from the Debian archive unstable we hereby close the associated bug reports. We are sorry that we couldn't deal with your issue properly. For details on the removal, please see https://bugs.debian.org/916837 The version of this package that was in Debian prior to this removal can still be found using http://snapshot.debian.org/. Please note that the changes have been done on the master archive and will not propagate to any mirrors until the next dinstall run at the earliest. This message was generated automatically; if you believe that there is a problem with it please contact the archive administrators by mailing [email protected]. Debian distribution maintenance software pp. Scott Kitterman (the ftpmaster behind the curtain)
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