** Description changed:
- After glibc maintainers changed "math-vector-fortran.h" install
- directory, gfortran can no longer use it.
+ After ubuntu-glibc maintainers changed "math-vector-fortran.h" install
+ directory (LP#1861353), gfortran can no longer use it.
This the old 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
+ 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 sinn
- U sin@@GLIBC_2.2.5
- U sinf@@GLIBC_2.2.5
+ $ nm ./test.x | grep sinn
+ 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
- !
+ 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
...
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!).
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https://bugs.launchpad.net/bugs/1879092
Title:
gfortran can't use vectorized functions.
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