Public bug reported: When compiling a program with -O3 and -mssse3, gcc 9 may generate code with incorrect behavior. The gcc master branch does not have this issue, so I was able to bisect the fix to PR92420 (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92420). This fix should be backported to gcc 9, at a minimum.
I also minimized the issue to a single file which is attached. The commit for the PR referenced above also contains its own test case. Tested on Ubuntu 19.10 with 9.2.1-9ubuntu2 and Ubuntu 20.04 with 9.2.1-25ubuntu1. ** Affects: gcc-9 (Ubuntu) Importance: Undecided Status: New ** Attachment added: "Test case based on broken program due to compiler" https://bugs.launchpad.net/bugs/1860876/+attachment/5322921/+files/gcc-test1.c -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1860876 Title: wrong code generated with -O3 and -mssse3 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gcc-9/+bug/1860876/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs