Hello world, the attached patch fixes three problems with DO loop index warnings:
- DO loops in contained procedures were not checked - Zero-trip loops gave a false positive - DO loops in blocks gave the same warning twice plus it fixes the resulting fallout from the test suite. Regression-tested. OK for trunk? I also think that this is something that could be safely backported to gcc-9. 2019-08-12 Thomas Koenig <tkoe...@gcc.gnu.org> PR fortran/91424 * frontend-passes.c (do_subscript): Do not warn for an expression a second time. Do not warn about a zero-trip loop. (doloop_warn): Also look at contained namespaces. 2019-08-12 Thomas Koenig <tkoe...@gcc.gnu.org> PR fortran/91424 * gfortran.dg/do_subscript_3.f90: New test. * gfortran.dg/do_subscript_4.f90: New test. * gfortran.dg/pr70754.f90: Use indices that to not overflow. 2019-08-12 Thomas Koenig <tkoe...@gcc.gnu.org> PR fortran/91422 * testsuite/libgomp.oacc-fortran/routine-7.f90: Correct array dimension.
! { dg-do compile } ! PR fortran/91424 ! Check that only one warning is issued inside blocks, and that ! warnings are also issued for contained subroutines. program main real :: a(5) block integer :: j do j=0, 5 ! { dg-warning "out of bounds" } a(j) = 2. ! { dg-warning "out of bounds" } end do end block call x contains subroutine x integer :: i do i=1,6 ! { dg-warning "out of bounds" } a(i) = 2. ! { dg-warning "out of bounds" } end do end subroutine x end program main
Index: gcc/fortran/frontend-passes.c =================================================================== --- gcc/fortran/frontend-passes.c (revision 273855) +++ gcc/fortran/frontend-passes.c (working copy) @@ -2556,6 +2556,12 @@ do_subscript (gfc_expr **e) if (in_assoc_list) return 0; + /* We already warned about this. */ + if (v->do_not_warn) + return 0; + + v->do_not_warn = 1; + for (ref = v->ref; ref; ref = ref->next) { if (ref->type == REF_ARRAY && ref->u.ar.type == AR_ELEMENT) @@ -2608,7 +2614,6 @@ do_subscript (gfc_expr **e) else have_do_start = false; - if (dl->ext.iterator->end->expr_type == EXPR_CONSTANT) { have_do_end = true; @@ -2620,6 +2625,17 @@ do_subscript (gfc_expr **e) if (!have_do_start && !have_do_end) return 0; + /* No warning inside a zero-trip loop. */ + if (have_do_start && have_do_end) + { + int sgn, cmp; + + sgn = mpz_cmp_ui (do_step, 0); + cmp = mpz_cmp (do_end, do_start); + if ((sgn > 0 && cmp < 0) || (sgn < 0 && cmp > 0)) + break; + } + /* May have to correct the end value if the step does not equal one. */ if (have_do_start && have_do_end && mpz_cmp_ui (do_step, 1) != 0) @@ -2761,6 +2777,12 @@ static void doloop_warn (gfc_namespace *ns) { gfc_code_walker (&ns->code, doloop_code, do_function, NULL); + + for (ns = ns->contained; ns; ns = ns->sibling) + { + if (ns->code == NULL || ns->code->op != EXEC_BLOCK) + doloop_warn (ns); + } } /* This selction deals with inlining calls to MATMUL. */ Index: gcc/testsuite/gfortran.dg/pr70754.f90 =================================================================== --- gcc/testsuite/gfortran.dg/pr70754.f90 (revision 273855) +++ gcc/testsuite/gfortran.dg/pr70754.f90 (working copy) @@ -18,12 +18,13 @@ contains integer (ii4), dimension(40,40) :: c integer i, j - do i=1,20 - b(i,j) = 123 * a(i,j) + 34 * a(i,j+1) & - + 34 * a(i,j-1) + a(i+1,j+1) & - + a(i+1,j-1) + a(i-1,j+1) & - + a(i-1,j-1) - c(i,j) = 123 + j = 10 + do i=11,30 + b(i,j) = 123 * a(i,j) + 34 * a(i,j+1) & + + 34 * a(i,j-1) + a(i+1,j+1) & + + a(i+1,j-1) + a(i-1,j+1) & + + a(i-1,j-1) + c(i,j) = 123 end do where ((xyz(:,:,2) /= 0) .and. (c /= 0)) Index: libgomp/testsuite/libgomp.oacc-fortran/routine-7.f90 =================================================================== --- libgomp/testsuite/libgomp.oacc-fortran/routine-7.f90 (revision 273855) +++ libgomp/testsuite/libgomp.oacc-fortran/routine-7.f90 (working copy) @@ -109,7 +109,7 @@ end subroutine gang subroutine seq (a) !$acc routine seq - integer, intent (inout) :: a(M) + integer, intent (inout) :: a(N) integer :: i do i = 1, N
! { dg-do compile } ! PR 91424 - this used to warn although the DO loop is zero trip. program main implicit none integer :: i real :: a(2) do i=1,3,-1 a(i) = 2. end do print *,a end program main