Hi, This patch tightens up error checking for array references used in OpenACC clauses such that they must now be contiguous. I believe this matches up to the spec (as of 2.6). I've tried to make it so an error only triggers if the compiler is sure that a given array expression must be non-contiguous at compile time, although this errs on the side of potentially allowing the user to shoot themselves in the foot at runtime: at least one existing test in the testsuite appears to expect that behaviour.
This hopefully addresses Tobias's concern in: https://gcc.gnu.org/ml/gcc-patches/2019-12/msg01439.html In particular, with the error checking, we no longer get an ICE for the example given in that message. The new check also catches a test case that appears to have been relying on undefined behaviour. Tested with offloading to NVPTX. OK for trunk? Thanks, Julian ChangeLog 2020-01-04 Julian Brown <jul...@codesourcery.com> PR fortran/93025 gcc/fortran/ * openmp.c (resolve_omp_clauses): Check array references for contiguity. gcc/testsuite/ * gfortran.dg/goacc/mapping-tests-2.f90: New test. * gfortran.dg/goacc/subarrays.f95: Expect rejection of non-contiguous array. --- gcc/fortran/openmp.c | 29 +++++++++++++---- .../gfortran.dg/goacc/mapping-tests-2.f90 | 32 +++++++++++++++++++ gcc/testsuite/gfortran.dg/goacc/subarrays.f95 | 2 +- 3 files changed, 55 insertions(+), 8 deletions(-) create mode 100644 gcc/testsuite/gfortran.dg/goacc/mapping-tests-2.f90 diff --git a/gcc/fortran/openmp.c b/gcc/fortran/openmp.c index 78351b190f7..71308c0235c 100644 --- a/gcc/fortran/openmp.c +++ b/gcc/fortran/openmp.c @@ -4533,13 +4533,28 @@ resolve_omp_clauses (gfc_code *code, gfc_omp_clauses *omp_clauses, /* Look through component refs to find last array reference. */ if (openacc && resolved) - while (array_ref - && (array_ref->type == REF_COMPONENT - || (array_ref->type == REF_ARRAY - && array_ref->next - && (array_ref->next->type - == REF_COMPONENT)))) - array_ref = array_ref->next; + { + /* The "!$acc cache" directive allows rectangular + subarrays to be specified, with some restrictions + on the form of bounds (not implemented). + Only raise an error here if we're really sure the + array isn't contiguous. An expression such as + arr(-n:n,-n:n) could be contiguous even if it looks + like it may not be. */ + if (list != OMP_LIST_CACHE + && !gfc_is_simply_contiguous (n->expr, false, true) + && gfc_is_not_contiguous (n->expr)) + gfc_error ("Array is not contiguous at %L", + &n->where); + + while (array_ref + && (array_ref->type == REF_COMPONENT + || (array_ref->type == REF_ARRAY + && array_ref->next + && (array_ref->next->type + == REF_COMPONENT)))) + array_ref = array_ref->next; + } } if (array_ref || (n->expr diff --git a/gcc/testsuite/gfortran.dg/goacc/mapping-tests-2.f90 b/gcc/testsuite/gfortran.dg/goacc/mapping-tests-2.f90 new file mode 100644 index 00000000000..1372f6af53e --- /dev/null +++ b/gcc/testsuite/gfortran.dg/goacc/mapping-tests-2.f90 @@ -0,0 +1,32 @@ +subroutine foo + type t + integer :: i, j + end type t + + type t2 + type(t) :: cc(3) + end type t2 + + type(t) x, y(3) + type(t2) :: z(3) + + ! OK - map whole aggregated variable +!$acc enter data copyin(x) + ! map(to:x [len: 8]) + + ! OK - map two components of the aggregated variable +!$acc enter data copyin(x%j, x%i) + + ! Bad - we cannot mix full-object and component accesses +!$acc enter data copyin(x, x%i) +! { dg-error "Symbol .x. has mixed component and non-component accesses" "" { target "*-*-*" } 21 } + + ! Bad - we cannot do a strided access of 'x' + ! No C/C++ equivalent +!$acc enter data copyin(y(:)%i) +! { dg-error "Array is not contiguous" "" { target "*-*-*" } 26 } + + ! Bad - again, a strided access +!$acc enter data copyin(z(1)%cc(:)%i) +! { dg-error "Array is not contiguous" "" { target "*-*-*" } 30 } +end diff --git a/gcc/testsuite/gfortran.dg/goacc/subarrays.f95 b/gcc/testsuite/gfortran.dg/goacc/subarrays.f95 index f6adde459f4..fa0378550e9 100644 --- a/gcc/testsuite/gfortran.dg/goacc/subarrays.f95 +++ b/gcc/testsuite/gfortran.dg/goacc/subarrays.f95 @@ -27,7 +27,7 @@ program test ! { dg-error "'a' in MAP clause" "" { target *-*-* } .-2 } !$acc end parallel - !$acc parallel copy (b(1:3,2:4)) + !$acc parallel copy (b(1:3,2:4)) ! { dg-error "Array is not contiguous" } !$acc end parallel !$acc parallel copy (b(2:3)) ! { dg-error "Rank mismatch" "" { target *-*-* } .-1 } -- 2.23.0
