Your message dated Tue, 20 Sep 2016 22:15:11 +0000 with message-id <[email protected]> and subject line Bug#838316: Removed package(s) from unstable has caused the Debian Bug report #772436, regarding aarch64 optimization bug 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.) -- 772436: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=772436 Debian Bug Tracking System Contact [email protected] with problems
--- Begin Message ---Package: gcc-4.9 Version: 4.9.1-19 Severity: normal I have a minimal reproducable test case in a git repo here: https://github.com/erikd/gcc-aarch64-optimization-bug which contails a test program which passes when run with optimization flags "-O1" and fails with "-O1 -fschedule-insns". Cloning that repo under aarch64 and doing: CC=gcc-4.9 make clean check compiles and runs the program with both sets of optimization flags and displays success or failure. It does not hwoever fail on aarch64 with gcc-4.8 or with gcc-snapshot, nor does it fail with any version of GCC on any other architecture. There is a usefule comment from Måns Rullgård on G+: https://plus.google.com/u/0/+ErikdeCastroLopo/posts/F2BPxT7g1Gx OK, it's a gcc bug. For some unfathomable reason, it chooses to calculate "mask = ~0u >> (32 - numBits)" in a vector register by means of left-shifting by -(32 - numBits). It then subtracts (bitPos & 7) from the negated value and uses this as the shift amount of a regular shift instruction in "mask <<= shift" which is obviously nonsense. This behaviour (and the bug) was introduced in rev 202020 (git 5674183), and reverting this commit makes things work again. I believe the -fschedule-insns flag is a red herring. It probably merely stirs up the code in a way that makes the real bug trigger. Older discussion about this problem here: https://plus.google.com/u/0/+ThomasRuecker/posts/e9uxoUyk3Bk -- System Information: Debian Release: 8.0 APT prefers unstable APT policy: (500, 'unstable') Architecture: arm64 (aarch64) Kernel: Linux 3.16.0-4-amd64 (SMP w/4 CPU cores) Locale: LANG=en_AU.UTF-8, LC_CTYPE=en_AU.UTF-8 (charmap=UTF-8) (ignored: LC_ALL set to en_AU.UTF-8) Shell: /bin/sh linked to /bin/dash Init: unable to detect Versions of packages gcc-4.9 depends on: ii binutils 2.24.90.20141201-1 ii cpp-4.9 4.9.2-5 ii gcc-4.9-base 4.9.2-5 ii libc6 2.19-13 ii libcloog-isl4 0.18.2-1+b2 ii libgcc-4.9-dev 4.9.2-5 ii libgmp10 2:6.0.0+dfsg-6 ii libisl10 0.12.2-2+b2 ii libmpc3 1.0.2-1+b2 ii libmpfr4 3.1.2-1+b2 ii zlib1g 1:1.2.8.dfsg-2+b1 Versions of packages gcc-4.9 recommends: ii libc6-dev 2.19-13 Versions of packages gcc-4.9 suggests: pn gcc-4.9-doc <none> pn gcc-4.9-locales <none> pn libasan1-dbg <none> pn libatomic1-dbg <none> pn libcilkrts5-dbg <none> pn libgcc1-dbg <none> pn libgomp1-dbg <none> pn libitm1-dbg <none> pn liblsan0-dbg <none> pn libquadmath-dbg <none> pn libtsan0-dbg <none> pn libubsan0-dbg <none> -- no debconf information
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--- Begin Message ---Version: 4.9.4-2+rm Dear submitter, as the package gcc-4.9 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/838316 The version of this package that was in Debian prior to this removal can still be found using http://snapshot.debian.org/. 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. Chris Lamb (the ftpmaster behind the curtain)
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