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From: "spop at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/40979] induct benchmark 60% slower when compiled with -fgraphite-identity Date: Mon, 31 Jan 2011 18:53:00 -0000 [thread overview] Message-ID: <bug-40979-4-bUfVk6StSc@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-40979-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40979 --- Comment #11 from Sebastian Pop <spop at gcc dot gnu.org> 2011-01-31 18:12:38 UTC --- Here is a reduced testcase from induct.f90 for the first loop not vectorized with -fgraphite-identity: module mqc_m integer, parameter, private :: longreal = selected_real_kind(15,90) contains subroutine mutual_ind_quad_cir_coil (m, l12) real (kind = longreal), dimension(9), save :: w2gauss, w1gauss real (kind = longreal) :: l12_lower, numerator real (kind = longreal), dimension(3) :: current_vector, coil_current_vec w2gauss(1) = 16.0_longreal/81.0_longreal w1gauss(5) = 0.3302393550_longreal do i = 1, 2*m do j = 1, 9 do k = 1, 9 numerator = w1gauss(j) * w2gauss(k) * & dot_product(coil_current_vec,current_vector) l12_lower = l12_lower + numerator end do end do end do l12 = l12_lower end subroutine mutual_ind_quad_cir_coil end module mqc_m The problem seems to be that graphite introduces a Commutative_Associative_Reduction array that confuses the vectorizer. I looked at how to improve translate_scalar_reduction_to_array in order to avoid the creation of the temporary array, but it seems to be difficult as the result is written to memory under a different type than the reduction itself: l12_lower is a real whereas l12 is an integer: l12_lower_200 = some_computation; # l12_lower_9 = PHI <l12_lower_16(D)(2), l12_lower_200(9)> D.1585_43 = (integer(kind=4)) l12_lower_9; # .MEM_48 = VDEF <.MEM_47> *l12_44(D) = D.1585_43; so we cannot use *l12_44(D) as a data reference in the loop to perform the reduction as it does not have the same precision as l12_lower: it seems to me that we cannot avoid creating the temporary array. The solution could be to clean up the temporary arrays after graphite.
next prev parent reply other threads:[~2011-01-31 18:12 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <bug-40979-4@http.gcc.gnu.org/bugzilla/> 2011-01-26 10:45 ` dominiq at lps dot ens.fr 2011-01-26 14:43 ` howarth at nitro dot med.uc.edu 2011-01-31 18:53 ` spop at gcc dot gnu.org [this message] 2011-01-31 19:36 ` dominiq at lps dot ens.fr 2011-02-01 11:35 ` rguenth at gcc dot gnu.org 2011-02-01 11:45 ` rguenth at gcc dot gnu.org 2011-02-01 16:47 ` spop at gcc dot gnu.org 2011-02-01 17:18 ` rguenth at gcc dot gnu.org 2011-02-01 17:23 ` sebpop at gmail dot com 2011-02-01 17:51 ` sebpop at gmail dot com 2011-02-01 18:22 ` dominiq at lps dot ens.fr 2011-02-01 21:19 ` howarth at nitro dot med.uc.edu 2011-02-01 21:22 ` spop at gcc dot gnu.org 2011-02-02 15:53 ` spop at gcc dot gnu.org 2011-02-02 15:59 ` spop at gcc dot gnu.org 2009-08-06 0:19 [Bug middle-end/40979] New: " howarth at nitro dot med dot uc dot edu 2009-08-06 0:23 ` [Bug middle-end/40979] " spop at gcc dot gnu dot org 2009-08-12 14:58 ` spop at gcc dot gnu dot org 2009-08-13 2:26 ` howarth at nitro dot med dot uc dot edu 2009-08-14 11:59 ` dominiq at lps dot ens dot fr 2009-12-14 19:24 ` spop at gcc dot gnu dot org 2010-02-25 15:23 ` dominiq at lps dot ens dot fr 2010-02-25 17:26 ` dominiq at lps dot ens dot fr 2010-03-10 1:57 ` howarth at nitro dot med dot uc dot edu 2010-03-15 14:21 ` dominiq at lps dot ens dot fr
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