From d7e3855d5dd8c001bb65dc7da1cda0249bfc2986 Mon Sep 17 00:00:00 2001 From: Thomas Koenig Date: Tue, 6 Jul 2021 07:04:09 +0200 Subject: [PATCH] Do not replace variable op variable in I/O implied DO loop replacement. This PR came about because index expressions of the form k+k in implied DO loops in I/O statements were considered for replacement by array slices. Fixed by only doing the transformation if the expression is of the type expr OP contastant. gcc/fortran/ChangeLog: PR fortran/100227 * frontend-passes.c (traverse_io_block): Adjust test for when a variable is eligible for the transformation to array slice. gcc/testsuite/ChangeLog: PR fortran/100227 * gfortran.dg/implied_do_io_7.f90: New test. --- gcc/fortran/frontend-passes.c | 4 ++-- gcc/testsuite/gfortran.dg/implied_do_io_7.f90 | 16 ++++++++++++++++ 2 files changed, 18 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/gfortran.dg/implied_do_io_7.f90 diff --git a/gcc/fortran/frontend-passes.c b/gcc/fortran/frontend-passes.c index 72a4e04..996dcc2 100644 --- a/gcc/fortran/frontend-passes.c +++ b/gcc/fortran/frontend-passes.c @@ -1299,8 +1299,8 @@ traverse_io_block (gfc_code *code, bool *has_reached, gfc_code *prev) std::swap (start->value.op.op1, start->value.op.op2); gcc_fallthrough (); case INTRINSIC_MINUS: - if ((start->value.op.op1->expr_type!= EXPR_VARIABLE - && start->value.op.op2->expr_type != EXPR_CONSTANT) + if (start->value.op.op1->expr_type!= EXPR_VARIABLE + || start->value.op.op2->expr_type != EXPR_CONSTANT || start->value.op.op1->ref) return false; if (!stack_top || !stack_top->iter diff --git a/gcc/testsuite/gfortran.dg/implied_do_io_7.f90 b/gcc/testsuite/gfortran.dg/implied_do_io_7.f90 new file mode 100644 index 0000000..63927aa --- /dev/null +++ b/gcc/testsuite/gfortran.dg/implied_do_io_7.f90 @@ -0,0 +1,16 @@ +! { dg-do run } +! PR 100227 - this was falsely optimized, leading to nonsense results. +! Original test case by "Mathieu". + +program p + implicit none + integer, parameter :: nbmode = 3 + integer :: k + real :: mass(nbmode*2) + character (len=80) :: line + do k = 1, nbmode*2 + mass(k) = k + end do + write (unit=line,fmt='(*(F6.2))') (mass(k+k), k=1,nbmode) + if (line /= ' 2.00 4.00 6.00') stop 1 +end program -- 2.7.4