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Re: [patch, fortran] RFD: PR 56666 Allow suppression of zero-trip DO loop warning
- From: Thomas Koenig <tkoenig at netcologne dot de>
- To: Janus Weil <janus at gcc dot gnu dot org>
- Cc: "fortran at gcc dot gnu dot org" <fortran at gcc dot gnu dot org>, gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Sun, 11 Aug 2013 23:51:00 +0200
- Subject: Re: [patch, fortran] RFD: PR 56666 Allow suppression of zero-trip DO loop warning
- References: <51FD2FA9 dot 508 at netcologne dot de> <CAKwh3qgx3LAO08hW9LXMXyU=6BsbzkBkvoAcYnEKomuy3b8WKg at mail dot gmail dot com>
Hi Janus,
> So: Ok for trunk from my side.
>
> However, I would prefer to disable the warning by default, but include
> it in -Wall.
Here's a patch to do just that.
Regression-tested (hence the changes to the existing test cases :-)
OK for trunk? Once it goes in, I will also update the WWW changes.
Thomas
2013-08-03 Thomas Koenig <tkoenig@gcc.gnu.org>
PR fortran/56666
* gfortran.h (gfc_option_t): Add warn_zerotrip.
* invoke.texi (-Wzerotrip): Document option.
* lang.opt (Wzerotrip): Add.
* options.c (gfc_init_options): Initialize warn_zerotrip.
(set_Wall): Add handling of warn_zerotrip.
(gfc_handle_option): Handle OPT_Wzerotrip.
* resolve.c (gfc_resolve_iterator): Honor
gfc_option.warn_zerotrip; update error message to show
how to suppress the warning.
2013-08-03 Thomas Koenig <tkoenig@gcc.gnu.org>
PR fortran/56666
* gfortran.dg/do_check_10.f90: New test.
* gfortran.dg/array_constructor_11.f90: Add -Wzerotrip to
dg-options.
* gfortran.dg/array_constructor_18.f90: Likewise.
* gfortran.dg/array_constructor_22.f90: Likewise.
* gfortran.dg/coarray_15.f90: Likewise.
* gfortran.dg/do_1.f90: Add -Wall to dg-options.
* gfortran.dg/do_3.F90: Add -Wzerotrip to dg-options.
* gfortran.dg/do_check_5.f90: Add -Wall to gd-options.
Index: fortran/gfortran.h
===================================================================
--- fortran/gfortran.h (Revision 201448)
+++ fortran/gfortran.h (Arbeitskopie)
@@ -2252,6 +2252,7 @@ typedef struct
int warn_align_commons;
int warn_real_q_constant;
int warn_unused_dummy_argument;
+ int warn_zerotrip;
int warn_realloc_lhs;
int warn_realloc_lhs_all;
int warn_compare_reals;
Index: fortran/invoke.texi
===================================================================
--- fortran/invoke.texi (Revision 201448)
+++ fortran/invoke.texi (Arbeitskopie)
@@ -954,6 +954,11 @@ This option is implied by @option{-Wextra}.
Warn if the pointer in a pointer assignment might be longer than the its
target. This option is implied by @option{-Wall}.
+@item -Wzerotrip
+@opindex @code{Wzerotrip}
+Warn if a @code{DO} loop is known to execute zero times at compile
+time. This option is implied by @option{-Wall}.
+
@item -Werror
@opindex @code{Werror}
@cindex warnings, to errors
Index: fortran/lang.opt
===================================================================
--- fortran/lang.opt (Revision 201448)
+++ fortran/lang.opt (Arbeitskopie)
@@ -293,6 +293,10 @@ Wunused-dummy-argument
Fortran Warning
Warn about unused dummy arguments.
+Wzerotrip
+Fortran Warning
+Warn about zero-trip DO loops
+
cpp
Fortran Negative(nocpp)
Enable preprocessing
Index: fortran/options.c
===================================================================
--- fortran/options.c (Revision 201448)
+++ fortran/options.c (Arbeitskopie)
@@ -109,6 +109,7 @@ gfc_init_options (unsigned int decoded_options_cou
gfc_option.warn_align_commons = 1;
gfc_option.warn_real_q_constant = 0;
gfc_option.warn_unused_dummy_argument = 0;
+ gfc_option.warn_zerotrip = 0;
gfc_option.warn_realloc_lhs = 0;
gfc_option.warn_realloc_lhs_all = 0;
gfc_option.warn_compare_reals = 0;
@@ -466,6 +467,7 @@ set_Wall (int setting)
gfc_option.warn_real_q_constant = setting;
gfc_option.warn_unused_dummy_argument = setting;
gfc_option.warn_target_lifetime = setting;
+ gfc_option.warn_zerotrip = setting;
warn_return_type = setting;
warn_uninitialized = setting;
@@ -747,6 +749,10 @@ gfc_handle_option (size_t scode, const char *arg,
gfc_option.warn_unused_dummy_argument = value;
break;
+ case OPT_Wzerotrip:
+ gfc_option.warn_zerotrip = value;
+ break;
+
case OPT_fall_intrinsics:
gfc_option.flag_all_intrinsics = 1;
break;
Index: fortran/resolve.c
===================================================================
--- fortran/resolve.c (Revision 201448)
+++ fortran/resolve.c (Arbeitskopie)
@@ -6282,8 +6282,10 @@ gfc_resolve_iterator (gfc_iterator *iter, bool rea
sgn = mpfr_sgn (iter->step->value.real);
cmp = mpfr_cmp (iter->end->value.real, iter->start->value.real);
}
- if ((sgn > 0 && cmp < 0) || (sgn < 0 && cmp > 0))
- gfc_warning ("DO loop at %L will be executed zero times",
+ if (gfc_option.warn_zerotrip &&
+ ((sgn > 0 && cmp < 0) || (sgn < 0 && cmp > 0)))
+ gfc_warning ("DO loop at %L will be executed zero times"
+ " (use -Wno-zerotrip to suppress)",
&iter->step->where);
}
Index: testsuite/gfortran.dg/array_constructor_11.f90
===================================================================
--- testsuite/gfortran.dg/array_constructor_11.f90 (Revision 201448)
+++ testsuite/gfortran.dg/array_constructor_11.f90 (Arbeitskopie)
@@ -1,6 +1,7 @@
! Like array_constructor_6.f90, but check iterators with non-default stride,
! including combinations which lead to zero-length vectors.
! { dg-do run }
+! { dg-options "-Wzerotrip" }
program main
implicit none
call build (77)
Index: testsuite/gfortran.dg/array_constructor_18.f90
===================================================================
--- testsuite/gfortran.dg/array_constructor_18.f90 (Revision 201448)
+++ testsuite/gfortran.dg/array_constructor_18.f90 (Arbeitskopie)
@@ -1,4 +1,5 @@
! { dg-do compile }
+! { dg-options "-Wzerotrip" }
! Tests the fix for PR32875, in which the character length for the
! array constructor would get lost in simplification and would lead
! the error 'Not Implemented: complex character array constructor'.
Index: testsuite/gfortran.dg/array_constructor_22.f90
===================================================================
--- testsuite/gfortran.dg/array_constructor_22.f90 (Revision 201448)
+++ testsuite/gfortran.dg/array_constructor_22.f90 (Arbeitskopie)
@@ -1,4 +1,5 @@
! { dg-do compile }
+! { dg-options "-Wzerotrip" }
! PR34990 ICE in gfc_typenode_for_spec, at fortran/trans-types.c:842
! Test case that of the reporters.
module test
Index: testsuite/gfortran.dg/coarray_15.f90
===================================================================
--- testsuite/gfortran.dg/coarray_15.f90 (Revision 201448)
+++ testsuite/gfortran.dg/coarray_15.f90 (Arbeitskopie)
@@ -1,5 +1,5 @@
! { dg-do run }
-! { dg-options "-fcoarray=single" }
+! { dg-options "-fcoarray=single -Wzerotrip" }
!
! PR fortran/18918
!
Index: testsuite/gfortran.dg/do_1.f90
===================================================================
--- testsuite/gfortran.dg/do_1.f90 (Revision 201448)
+++ testsuite/gfortran.dg/do_1.f90 (Arbeitskopie)
@@ -1,4 +1,5 @@
! { dg-do run }
+! { dg-options "-Wall" }
! Program to check corner cases for DO statements.
program do_1
implicit none
Index: testsuite/gfortran.dg/do_3.F90
===================================================================
--- testsuite/gfortran.dg/do_3.F90 (Revision 201448)
+++ testsuite/gfortran.dg/do_3.F90 (Arbeitskopie)
@@ -1,5 +1,5 @@
! { dg-do run }
-! { dg-options "-std=legacy -ffree-line-length-none -fno-range-check -fwrapv" }
+! { dg-options "-std=legacy -ffree-line-length-none -fno-range-check -fwrapv -Wzerotrip" }
program test
integer :: count
integer :: i
Index: testsuite/gfortran.dg/do_check_5.f90
===================================================================
--- testsuite/gfortran.dg/do_check_5.f90 (Revision 201448)
+++ testsuite/gfortran.dg/do_check_5.f90 (Arbeitskopie)
@@ -1,5 +1,5 @@
! { dg-do compile }
-!
+! { dg-options "-Wall" }
! PR/fortran 38432
! DO-loop compile-time checks
!
! { dg-do compile }
! { dg-options "-Wall -Wno-zerotrip" }
program main
do i=1,0
print *,i
end do
end program main