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From: "nadavhalahmi560 at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug fortran/100855] New: pow run time gfortran vs ifort Date: Tue, 01 Jun 2021 13:01:29 +0000 [thread overview] Message-ID: <bug-100855-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100855 Bug ID: 100855 Summary: pow run time gfortran vs ifort Product: gcc Version: 11.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: fortran Assignee: unassigned at gcc dot gnu.org Reporter: nadavhalahmi560 at gmail dot com Target Milestone: --- I wrote the code below: ``` program power implicit none real :: sum, n, q integer :: i, j integer :: limit real :: start, finish sum = 0d0 limit = 10000 n = 2.0 q = 0.5 call CPU_TIME(start) do j=1,limit do i=1, limit n = n*q sum = sum + (i ** (0.05 + n)) end do end do call CPU_TIME(finish) print *, sum print '("Time = ",f6.3," seconds.")',finish-start end program power ``` and compiled it using: ifort pow.f90 -O3 -no-vec -o intel.out gfortran pow.f90 -O3 -fno-tree-vectorize -o gnu.out When I run `./intel.out` I get the following output: 3.3554432E+07 Time = 1.615 seconds. When I run `./gnu.out` I get the following output: 33554432.0 Time = 7.817 seconds. Therefore, gfortran is much slower than ifort. I get similar behavior for `log` and `exp` functions. gfortran -v: Using built-in specs. COLLECT_GCC=gfortran COLLECT_LTO_WRAPPER=/software/x86_64/3.10.0/gcc/11.1.0/libexec/gcc/x86_64-pc-linux-gnu/11.1.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: ../configure --prefix=/software/x86_64/3.10.0/gcc/11.1.0 --disable-multilib Thread model: posix Supported LTO compression algorithms: zlib gcc version 11.1.0 (GCC) ifort -v: ifort version 19.1.3.304
next reply other threads:[~2021-06-01 13:01 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-01 13:01 nadavhalahmi560 at gmail dot com [this message] 2021-06-01 16:19 ` [Bug fortran/100855] " kargl at gcc dot gnu.org 2021-06-01 17:20 ` anlauf at gcc dot gnu.org 2021-06-02 7:52 ` rguenth at gcc dot gnu.org 2021-06-02 9:37 ` nadavhalahmi560 at gmail dot com 2021-06-02 9:38 ` nadavhalahmi560 at gmail dot com 2021-06-02 16:34 ` dominiq at lps dot ens.fr 2021-06-03 8:21 ` nadavhalahmi560 at gmail dot com 2021-06-03 14:24 ` dominiq at lps dot ens.fr 2021-06-05 11:59 ` dominiq at lps dot ens.fr 2021-06-06 8:52 ` nadavhalahmi560 at gmail dot com
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