https://gcc.gnu.org/g:451b6dbf47595922518b96728677d1fafa11e2ad
commit r16-2213-g451b6dbf47595922518b96728677d1fafa11e2ad
Author: Tobias Burnus <tbur...@baylibre.com>
Date: Sat Jul 12 07:18:06 2025 +0200
Fortran/OpenACC: Permit PARAMETER as 'var' in clauses (+ ignore)
It turned out that other compilers permit (require?) named constants
to appear in clauses - and programs actually use this. OpenACC 3.4
added therefore the following:
In this spec, a _var_ (in italics) is one of the following:
...
* a named constant in Fortran.
plus
If during an optimization phase _var_ is removed by the compiler,
appearances of var in data clauses are ignored.
Thus, all errors related to PARAMETER are now downgraded, most
to a -Wsurprising warning, but for 'acc declare device_resident'
(which kind of makes sense), no warning is printed.
In trans-openmp.cc, those are ignored, unless I missed some code
path. (If so, I hope the middle end removes them; but before
removing them for the covered cases, the program just compiled &
linked fine.)
Note that 'ignore PARAMETER inside clauses' in trans-openmp.cc
would in principle also apply to expressions ('if (var)') but
those should be evaluated during 'resolve.cc' + 'openmp.cc' to
their (numeric, logical, string) value such that there should
be no issue.
gcc/fortran/ChangeLog:
* invoke.texi (-Wsurprising): Note about OpenACC warning
related to PARAMATER.
* openmp.cc (resolve_omp_clauses, gfc_resolve_oacc_declare):
Accept PARAMETER for OpenACC but add surprising warning.
* trans-openmp.cc (gfc_trans_omp_variable_list,
gfc_trans_omp_clauses): Ignore PARAMETER inside clauses.
gcc/testsuite/ChangeLog:
* gfortran.dg/goacc/parameter.f95: Add -Wsurprising flag
and update expected diagnostic.
* gfortran.dg/goacc/parameter-3.f90: New test.
* gfortran.dg/goacc/parameter-4.f90: New test.
Diff:
---
gcc/fortran/invoke.texi | 4 ++++
gcc/fortran/openmp.cc | 30 ++++++++++++++++++++-----
gcc/fortran/trans-openmp.cc | 13 ++++++++---
gcc/testsuite/gfortran.dg/goacc/parameter-3.f90 | 16 +++++++++++++
gcc/testsuite/gfortran.dg/goacc/parameter-4.f90 | 26 +++++++++++++++++++++
gcc/testsuite/gfortran.dg/goacc/parameter.f95 | 27 +++++++++++-----------
6 files changed, 94 insertions(+), 22 deletions(-)
diff --git a/gcc/fortran/invoke.texi b/gcc/fortran/invoke.texi
index da085d124f91..0b893e876a5d 100644
--- a/gcc/fortran/invoke.texi
+++ b/gcc/fortran/invoke.texi
@@ -1170,6 +1170,10 @@ A @code{CHARACTER} variable is declared with negative
length.
With @option{-fopenmp}, for fixed-form source code, when an @code{omx}
vendor-extension sentinel is encountered. (The equivalent @code{ompx},
used in free-form source code, is diagnosed by default.)
+
+@item
+With @option{-fopenacc}, when using named constances with clauses that
+take a variable as doing so has no effect.
@end itemize
@opindex Wtabs
diff --git a/gcc/fortran/openmp.cc b/gcc/fortran/openmp.cc
index fe0a47a6948b..f1acc00f561b 100644
--- a/gcc/fortran/openmp.cc
+++ b/gcc/fortran/openmp.cc
@@ -8895,15 +8895,21 @@ resolve_omp_clauses (gfc_code *code, gfc_omp_clauses
*omp_clauses,
if (list == OMP_LIST_MAP
&& n->sym->attr.flavor == FL_PARAMETER)
{
+ /* OpenACC since 3.4 permits for Fortran named constants, but
+ permits removing then as optimization is not needed and such
+ ignore them. Likewise below for FIRSTPRIVATE. */
if (openacc)
- gfc_error ("Object %qs is not a variable at %L; parameters"
- " cannot be and need not be copied", n->sym->name,
- &n->where);
+ gfc_warning (OPT_Wsurprising, "Clause for object %qs at %L is "
+ "ignored as parameters need not be copied",
+ n->sym->name, &n->where);
else
gfc_error ("Object %qs is not a variable at %L; parameters"
" cannot be and need not be mapped", n->sym->name,
&n->where);
}
+ else if (openacc && n->sym->attr.flavor == FL_PARAMETER)
+ gfc_warning (OPT_Wsurprising, "Clause for object %qs at %L is ignored"
+ " as it is a parameter", n->sym->name, &n->where);
else if (list != OMP_LIST_USES_ALLOCATORS)
gfc_error ("Object %qs is not a variable at %L", n->sym->name,
&n->where);
@@ -12756,9 +12762,21 @@ gfc_resolve_oacc_declare (gfc_namespace *ns)
&& (n->sym->attr.flavor != FL_PROCEDURE
|| n->sym->result != n->sym))
{
- gfc_error ("Object %qs is not a variable at %L",
- n->sym->name, &oc->loc);
- continue;
+ if (n->sym->attr.flavor != FL_PARAMETER)
+ {
+ gfc_error ("Object %qs is not a variable at %L",
+ n->sym->name, &oc->loc);
+ continue;
+ }
+ /* Note that OpenACC 3.4 permits name constants, but the
+ implementation is permitted to ignore the clause;
+ as semantically, device_resident kind of makes sense
+ (and the wording with it is a bit odd), the warning
+ is suppressed. */
+ if (list != OMP_LIST_DEVICE_RESIDENT)
+ gfc_warning (OPT_Wsurprising, "Object %qs at %L is ignored as"
+ " parameters need not be copied", n->sym->name,
+ &oc->loc);
}
if (n->expr && n->expr->ref->type == REF_ARRAY)
diff --git a/gcc/fortran/trans-openmp.cc b/gcc/fortran/trans-openmp.cc
index a2e70fca0b37..f3d7cd4ffee9 100644
--- a/gcc/fortran/trans-openmp.cc
+++ b/gcc/fortran/trans-openmp.cc
@@ -2792,8 +2792,13 @@ gfc_trans_omp_variable_list (enum omp_clause_code code,
gfc_omp_namelist *namelist, tree list,
bool declare_simd)
{
+ /* PARAMETER (named constants) are excluded as OpenACC 3.4 permits them now
+ as 'var' but permits compilers to ignore them. In expressions, it should
+ have been replaced by the value (and this function should not be called
+ anyway) and for var-using clauses, they should just be skipped. */
for (; namelist != NULL; namelist = namelist->next)
- if (namelist->sym->attr.referenced || declare_simd)
+ if ((namelist->sym->attr.referenced || declare_simd)
+ && namelist->sym->attr.flavor != FL_PARAMETER)
{
tree t = gfc_trans_omp_variable (namelist->sym, declare_simd);
if (t != error_mark_node)
@@ -4029,7 +4034,8 @@ gfc_trans_omp_clauses (stmtblock_t *block,
gfc_omp_clauses *clauses,
case OMP_LIST_MAP:
for (; n != NULL; n = n->next)
{
- if (!n->sym->attr.referenced)
+ if (!n->sym->attr.referenced
+ || n->sym->attr.flavor == FL_PARAMETER)
continue;
location_t map_loc = gfc_get_location (&n->where);
@@ -4986,7 +4992,8 @@ gfc_trans_omp_clauses (stmtblock_t *block,
gfc_omp_clauses *clauses,
case OMP_LIST_CACHE:
for (; n != NULL; n = n->next)
{
- if (!n->sym->attr.referenced)
+ if (!n->sym->attr.referenced
+ && n->sym->attr.flavor != FL_PARAMETER)
continue;
switch (list)
diff --git a/gcc/testsuite/gfortran.dg/goacc/parameter-3.f90
b/gcc/testsuite/gfortran.dg/goacc/parameter-3.f90
new file mode 100644
index 000000000000..2c8aa618cc22
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/goacc/parameter-3.f90
@@ -0,0 +1,16 @@
+! { dg-do compile }
+
+subroutine x
+ integer :: var
+ integer, parameter :: ilog = 0
+ integer, parameter :: array(*) = [11,22,33]
+ !$ACC DECLARE COPYIN(ilog, array, var, array) ! { dg-error "Symbol 'array'
present on multiple clauses" }
+end subroutine x
+
+integer :: a
+integer, parameter :: b = 4
+integer, parameter :: c(*) = [1,2,3]
+
+!$acc parallel copy(a,c,b,c) ! { dg-error "Symbol 'c' present on multiple
clauses" }
+!$acc end parallel
+end
diff --git a/gcc/testsuite/gfortran.dg/goacc/parameter-4.f90
b/gcc/testsuite/gfortran.dg/goacc/parameter-4.f90
new file mode 100644
index 000000000000..aadd7cffe810
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/goacc/parameter-4.f90
@@ -0,0 +1,26 @@
+! { dg-do compile }
+! { dg-additional-options "-fdump-tree-original" }
+
+subroutine x
+ integer :: var
+ integer, parameter :: ilog = 0
+ integer, parameter :: array(*) = [11,22,33]
+ !$ACC DECLARE COPYIN(ilog, array, var)
+end subroutine x
+
+integer :: a
+integer, parameter :: b = 4
+integer, parameter :: c(*) = [1,2,3]
+
+!$acc parallel copy(a,c,b)
+ a = c(2) + b
+!$acc end parallel
+
+!$acc parallel firstprivate(a,c,b)
+ a = c(2) + b
+!$acc end parallel
+end
+
+! { dg-final { scan-tree-dump-times "#pragma acc data map\\(to:var\\)" 1
"original" } }
+! { dg-final { scan-tree-dump-times "#pragma acc parallel map\\(tofrom:a\\)" 1
"original" } }
+! { dg-final { scan-tree-dump-times "#pragma acc parallel firstprivate\\(a\\)"
1 "original" } }
diff --git a/gcc/testsuite/gfortran.dg/goacc/parameter.f95
b/gcc/testsuite/gfortran.dg/goacc/parameter.f95
index b58133867217..a9bde4a67ec1 100644
--- a/gcc/testsuite/gfortran.dg/goacc/parameter.f95
+++ b/gcc/testsuite/gfortran.dg/goacc/parameter.f95
@@ -1,4 +1,5 @@
! { dg-do compile }
+! { dg-additional-options "-Wsurprising" }
module test
contains
@@ -6,37 +7,37 @@ contains
implicit none
integer :: i
integer, parameter :: a = 1
- !$acc declare device_resident (a) ! { dg-error "is not a variable" }
- !$acc data copy (a) ! { dg-error "not a variable" }
+ !$acc declare device_resident (a) ! (no warning here - for semi-good
reasons)
+ !$acc data copy (a) ! { dg-warning "Clause for object 'a' at .1. is
ignored as parameters need not be copied \\\[-Wsurprising\\\]" }
!$acc end data
- !$acc data deviceptr (a) ! { dg-error "not a variable" }
+ !$acc data deviceptr (a) ! { dg-warning "Clause for object 'a' at .1. is
ignored as parameters need not be copied \\\[-Wsurprising\\\]" }
!$acc end data
- !$acc parallel private (a) ! { dg-error "not a variable" }
+ !$acc parallel private (a) ! { dg-warning "Clause for object 'a' at .1. is
ignored as it is a parameter \\\[-Wsurprising\\\]" }
!$acc end parallel
- !$acc serial private (a) ! { dg-error "not a variable" }
+ !$acc serial private (a) ! { dg-warning "Clause for object 'a' at .1. is
ignored as it is a parameter \\\[-Wsurprising\\\]" }
!$acc end serial
- !$acc host_data use_device (a) ! { dg-error "not a variable" }
+ !$acc host_data use_device (a) ! { dg-warning "Clause for object 'a' at
.1. is ignored as it is a parameter \\\[-Wsurprising\\\]" }
!$acc end host_data
- !$acc parallel loop reduction(+:a) ! { dg-error "not a variable" }
+ !$acc parallel loop reduction(+:a) ! { dg-warning "Clause for object 'a'
at .1. is ignored as it is a parameter \\\[-Wsurprising\\\]" }
do i = 1,5
enddo
!$acc end parallel loop
- !$acc serial loop reduction(+:a) ! { dg-error "not a variable" }
+ !$acc serial loop reduction(+:a) ! { dg-warning "Clause for object 'a' at
.1. is ignored as it is a parameter \\\[-Wsurprising\\\]" }
do i = 1,5
enddo
!$acc end serial loop
!$acc parallel loop
do i = 1,5
- !$acc cache (a) ! { dg-error "not a variable" }
+ !$acc cache (a) ! { dg-warning "Clause for object 'a' at .1. is ignored
as it is a parameter \\\[-Wsurprising\\\]" }
enddo
!$acc end parallel loop
!$acc serial loop
do i = 1,5
- !$acc cache (a) ! { dg-error "not a variable" }
+ !$acc cache (a) ! { dg-warning "Clause for object 'a' at .1. is ignored
as it is a parameter \\\[-Wsurprising\\\]" }
enddo
!$acc end serial loop
- !$acc update device (a) ! { dg-error "not a variable" }
- !$acc update host (a) ! { dg-error "not a variable" }
- !$acc update self (a) ! { dg-error "not a variable" }
+ !$acc update device (a) ! { dg-warning "Clause for object 'a' at .1. is
ignored as parameters need not be copied \\\[-Wsurprising\\\]" }
+ !$acc update host (a) ! { dg-warning "Clause for object 'a' at .1. is
ignored as parameters need not be copied \\\[-Wsurprising\\\]" }
+ !$acc update self (a) ! { dg-warning "Clause for object 'a' at .1. is
ignored as parameters need not be copied \\\[-Wsurprising\\\]" }
end subroutine oacc1
end module test
