public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "foom at fuhm dot net" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/53364] New: [4.7/4.8 Regression] Wrong code generation Date: Tue, 15 May 2012 19:24:00 -0000 [thread overview] Message-ID: <bug-53364-4@http.gcc.gnu.org/bugzilla/> (raw) http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53364 Bug #: 53364 Summary: [4.7/4.8 Regression] Wrong code generation Classification: Unclassified Product: gcc Version: 4.7.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassigned@gcc.gnu.org ReportedBy: foom@fuhm.net On the following code, minimized from a much larger program: test.cpp ===================== #include <algorithm> struct A { int m_x; explicit A(int x) : m_x(x) {} operator int() const { return m_x; } }; struct B : public A { public: explicit B(int x) : A(x) {} }; int data = 1; int main() { B b = B(10); b = std::min(b, B(data)); return int(b); } ================= Running: g++ -O2 -c test.cpp With gcc version: g++ (Debian 4.7.0-8) 4.7.0 (which says it's built from r187339 on the gcc 4.7 branch). On architecture: x86-64 The program ought to return 1, but instead, it returns randomness. Running valgrind confirms that this program is using uninitialized values. Testing with the debian gcc-snapshot package (trunk rev 187013) shows the same bug. Testing with the debian gcc 4.6.3 package does not show the bug. Using -O1 does not show the bug. Using -O1 -fstrict-aliasing shows the bug.
next reply other threads:[~2012-05-15 19:22 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-05-15 19:24 foom at fuhm dot net [this message] 2012-05-16 4:13 ` [Bug c++/53364] " foom at fuhm dot net 2012-05-16 4:28 ` pinskia at gcc dot gnu.org 2012-05-16 4:54 ` foom at fuhm dot net 2012-05-16 8:54 ` glisse at gcc dot gnu.org 2012-05-16 10:32 ` [Bug tree-optimization/53364] " rguenth at gcc dot gnu.org 2012-05-16 10:38 ` rguenth at gcc dot gnu.org 2012-05-16 11:22 ` rguenth at gcc dot gnu.org 2012-05-16 13:11 ` rguenth at gcc dot gnu.org 2012-05-16 13:13 ` rguenth at gcc dot gnu.org 2012-05-16 13:19 ` rguenth at gcc dot gnu.org
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=bug-53364-4@http.gcc.gnu.org/bugzilla/ \ --to=gcc-bugzilla@gcc.gnu.org \ --cc=gcc-bugs@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).