gfortran can't use vectorized functions.

[Mehdi Chinoune]

[Impact]

After ubuntu-glibc maintainers changed "math-vector-fortran.h" install directory (LP#1861353), gfortran can no longer use it.

[Test Case]

This the old (good) behavior Ubuntu 19.10 gcc-9.2.1 glibc 2.30
$ gfortran -O3 -mavx2 vect_test.f90 -o test.x
$ nm ./test.x | grep sin
    U _ZGVdN4v_sin@@GLIBC_2.22
    U _ZGVdN8v_sinf@@GLIBC_2.22

After that change : Ubuntu 20.04 gcc-9.3.0 glibc 2.31
$ gfortran -O3 -mavx2 vect_test.f90 -o test.x
$ nm ./test.x | grep sin
    U sin@@GLIBC_2.2.5
    U sinf@@GLIBC_2.2.5

$ cat vect_test.f90
program test_vect
  implicit none
  integer, parameter :: n = 64*1024**2
  integer :: i
  integer(8) :: t1, t2, t0
  real(8) :: tic
  !
  real, allocatable :: a32(:), b32(:)
  real(8), allocatable :: a64(:), b64(:)
  !
  allocate( a32(n), a64(n))
  allocate( b32(n), b64(n))
  !
  call random_number(a32 )
  call random_number(a64 )
  !
  call system_clock(t0, tic)
  !
  do i = 1, n
    b32(i) = sin(a32(i))
  end do
  !
  call system_clock(t1)
  print*, (t1-t0)/tic
  !
  do i = 1, n
    b64(i) = sin(a64(i))
  end do
  !
  call system_clock(t2)
  print*, (t2-t1)/tic
  !
end program test_vect

Verbose:

Ubuntu 19.10
$ gfortran -O3 -mavx2 -v vect_test.f90 -o test.x
...
/usr/lib/gcc/x86_64-linux-gnu/9/f951 vect_test.f90 -quiet -dumpbase vect_test.f90 -mavx2 -mtune=generic -march=x86-64 -auxbase vect_test -O3 -version -fintrinsic-modules-path /usr/lib/gcc/x86_64-linux-gnu/9/finclude -fpre-include=/usr/include/finclude/math-vector-fortran.h -o /tmp/cc2E2K8s.s
...

Ubuntu 20.04
$ gfortran -O3 -mavx2 -v vect_test.f90 -o test.x
...
/usr/lib/gcc/x86_64-linux-gnu/9/f951 vect_test.f90 -quiet -dumpbase vect_test.f90 -mavx2 -mtune=generic -march=x86-64 -auxbase vect_test -O3 -version -fintrinsic-modules-path /usr/lib/gcc/x86_64-linux-gnu/9/finclude -o /tmp/cc4swJwz.s
...

[Other Info]

As you can see gfortran is not preincluding "math-vector-fortran.h" file on Ubuntu 20.04.
A workaround is to copy "math-vector-fortran.h" to /usr/include/finclude (which is empty!).

[Launchpad Janitor (janitor)]

This bug was fixed in the package glibc - 2.31-0ubuntu10

---------------
glibc (2.31-0ubuntu10) groovy; urgency=medium

  * Copy the fully conditionalized x86 variant for math-vector-fortran.h
    to /usr/include/finclude. On all architectures. LP: #1879092.
  * Backport x86 CET patches from the trunk.
  * debian/patches/git-updates.diff: update from upstream stable branch.
    - [23296] Data race in setting function descriptor during lazy binding
    - [25639] localedata: Some names of days and months wrongly spelt in Occitan
    - [25810] x32: Incorrect syscall entries with pointer, off_t and size_t
    - [25896] Incorrect prctl
    - [25902] Bad LOADARGS_N
    - [25966] Incorrect access of __x86_shared_non_temporal_threshold for x32
    - [25976] nss_compat: internal_end*ent may clobber errno, hiding ERANGE

 -- Matthias Klose <email address hidden> Thu, 11 Jun 2020 11:53:48 +0200

[Balint Reczey (rbalint)]

Queued for next upload at: https://code.launchpad.net/~ubuntu-core-dev/ubuntu/+source/glibc/+git/glibc

[Robie Basak (racb)]

Hello Mehdi, or anyone else affected,

Accepted glibc into focal-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/glibc/2.31-0ubuntu9.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-focal to verification-done-focal. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-focal. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Ubuntu SRU Bot (ubuntu-sru-bot)]

All autopkgtests for the newly accepted glibc (2.31-0ubuntu9.1) for focal have finished running.
The following regressions have been reported in tests triggered by the package:

prometheus-blackbox-exporter/0.13.0+ds-2 (armhf, amd64, ppc64el, s390x, arm64)
prometheus-pushgateway/1.0.0+ds-1 (armhf, amd64, ppc64el, s390x, arm64)
systemd/245.4-4ubuntu3.2 (s390x, amd64, ppc64el)
gfs2-utils/unknown (amd64)
hugo/0.68.3-1 (armhf, amd64, ppc64el, s390x, arm64)
grubzfs-testsuite/0.4.10 (amd64)
glibc/2.31-0ubuntu9.1 (armhf)
badger/2.0.1-3 (armhf, amd64, ppc64el, s390x, arm64)
resource-agents/1:4.5.0-2ubuntu2 (armhf)
etcd/3.2.26+dfsg-6 (amd64, ppc64el)
postgresql-multicorn/1.3.4-31-g9ff7875-3 (armhf, amd64, ppc64el, s390x)
gfs2-utils/3.2.0-3 (ppc64el, s390x, arm64)
scipy/1.3.3-3build1 (ppc64el)

Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-migration/focal/update_excuses.html#glibc

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

[Balint Reczey (rbalint)]

Tested 2.31-0ubuntu9.1 on Focal:

root@ff-gfortran:~# cat > vect_test.f90
program test_vect
  implicit none
  integer, parameter :: n = 64*1024**2
  integer :: i
  integer(8) :: t1, t2, t0
  real(8) :: tic
  !
  real, allocatable :: a32(:), b32(:)
  real(8), allocatable :: a64(:), b64(:)
  !
  allocate( a32(n), a64(n))
  allocate( b32(n), b64(n))
  !
  call random_number(a32 )
  call random_number(a64 )
  !
  call system_clock(t0, tic)
  !
  do i = 1, n
    b32(i) = sin(a32(i))
  end do
  !
  call system_clock(t1)
  print*, (t1-t0)/tic
  !
  do i = 1, n
    b64(i) = sin(a64(i))
  end do
  !
  call system_clock(t2)
  print*, (t2-t1)/tic
  !
end program test_vect
root@ff-gfortran:~# dpkg -l libc6
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-==============-=============-============-=================================
ii libc6:amd64 2.31-0ubuntu9 amd64 GNU C Library: Shared libraries
root@ff-gfortran:~# dpkg -l libc6 | cat
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-==============-=============-============-=================================
ii libc6:amd64 2.31-0ubuntu9 amd64 GNU C Library: Shared libraries
root@ff-gfortran:~# gfortran -O3 -mavx2 vect_test.f90 -o test.x
root@ff-gfortran:~# nm ./test.x | grep sin
                 U sin@@GLIBC_2.2.5
                 U sinf@@GLIBC_2.2.5
root@ff-gfortran:~# sed -i 's/backports/proposed/' /etc/apt/sources.list
root@ff-gfortran:~# apt update -qq
48 packages can be upgraded. Run 'apt list --upgradable' to see them.
root@ff-gfortran:~# apt install -qq libc6 libc-bin locales
The following package was automatically installed and is no longer required:
  libfreetype6
Use 'apt autoremove' to remove it.
The following additional packages will be installed:
  libc-dev-bin libc6-dev
Suggested packages:
  glibc-doc
The following packages will be upgraded:
  libc-bin libc-dev-bin libc6 libc6-dev locales
5 upgraded, 0 newly installed, 0 to remove and 43 not upgraded.
Need to get 9807 kB of archives.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n]
Preconfiguring packages ...
(Reading database ... 35617 files and directories currently installed.)
Preparing to unpack .../libc6-dev_2.31-0ubuntu9.1_amd64.deb ...
Unpacking libc6-dev:amd64 (2.31-0ubuntu9.1) over (2.31-0ubuntu9) ...
Preparing to unpack .../libc-dev-bin_2.31-0ubuntu9.1_amd64.deb ...
Unpacking libc-dev-bin (2.31-0ubuntu9.1) over (2.31-0ubuntu9) ...
Preparing to unpack .../libc6_2.31-0ubuntu9.1_amd64.deb ...
Unpacking libc6:amd64 (2.31-0ubuntu9.1) over (2.31-0ubuntu9) ...
Setting up libc6:amd64 (2.31-0ubuntu9.1) ...
(Reading database ... 35616 files and directories currently installed.)
Preparing to unpack .../locales_2.31-0ubuntu9.1_all.deb ...
Unpacking locales (2.31-0ubuntu9.1) over (2.31-0ubuntu9) .....

[Launchpad Janitor (janitor)]

This bug was fixed in the package glibc - 2.31-0ubuntu9.1

---------------
glibc (2.31-0ubuntu9.1) focal; urgency=medium

  [ Michael Hudson-Doyle ]
  * Mark tst-getpw as XFAIL on arm64. (LP: #1869364)

  [ Matthias Klose ]
  * Copy the fully conditionalized x86 variant for math-vector-fortran.h
    to /usr/include/finclude. On all architectures. (LP: #1879092)

  [ Balint Reczey ]
  * debian/gbp.conf: Add initial configuration
  * debian/control.in/main: Add Vcs-* pointing to Ubuntu packaging repository
  * debian/debhelper.in/libc.preinst: Fix setting LDCONFIG_NOTRIGGER
    (LP: #1889190)
  * Fall back to calling nanosleep syscall when __clock_nanosleep returns
    EINVAL due to CLOCK_REALTIME not being supported (LP: #1871129)
  * debian/testsuite-xfail-debian.mk: XFAIL tst-getpw on armhf, too
    (LP: #1869364)
  * XFAIL stdlib/tst-getrandom (LP: #1891403)

  [ Dimitri John Ledkov ]
  * debian/patches/powerpc: Cherrypick upstream patches to support POWER10
    optimized library loading. LP: #1887989

 -- Balint Reczey <email address hidden> Mon, 17 Aug 2020 22:02:52 +0200

[Brian Murray (brian-murray)]

The verification of the Stable Release Update for glibc has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.