OpenMP/Fortran: Fix loop-iter var privatization with !$OMP LOOP [PR108512]
Commit Message
I stumbled over a new FAIL (regression) in sollve_vv today, which was due to an
odd corner case (see commit log for a description).
The mentioned in-scan error is tested for in gomp/loop-2.f90 ("'inscan' REDUCTION
clause on construct other than DO, SIMD, DO SIMD, PARALLEL DO, PARALLEL DO SIMD").
I hope that this patch covers all cases and no other surprises exist...
OK for mainline?
* * *
The ICE is new in GCC 13 due to the duplicate diagnostic (cf. PR); the original issue
existed before but seemingly did not affect the code, at least the sollve_vv testcase
passed before.
Still, it could be backported to GCC 12. (Fortran '!$omp loop' support was added with r12-1206.)
Thoughts?
Tobias
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Comments
On Tue, Jan 24, 2023 at 04:24:07PM +0100, Tobias Burnus wrote:
> gcc/fortran/ChangeLog:
>
> PR fortran/108512
> * openmp.cc (gfc_resolve_omp_do_blocks): Don't check 'inscan'
> restrictions for loop as rejected elsewhere.
> (gfc_resolve_do_iterator): Set a source location for added
> 'private'-clause arguments.
> * resolve.cc (gfc_resolve_code): Call gfc_resolve_omp_do_blocks
> also for EXEC_OMP_LOOP.
>
> gcc/testsuite/ChangeLog:
>
> PR fortran/108512
> * gfortran.dg/gomp/loop-5.f90: New test.
>
> gcc/fortran/openmp.cc | 5 +-
> gcc/fortran/resolve.cc | 1 +
> gcc/testsuite/gfortran.dg/gomp/loop-5.f90 | 84 +++++++++++++++++++++++++++++++
> 3 files changed, 89 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/fortran/openmp.cc b/gcc/fortran/openmp.cc
> index cc1eab90b8c..7673a52249f 100644
> --- a/gcc/fortran/openmp.cc
> +++ b/gcc/fortran/openmp.cc
> @@ -9056,7 +9056,9 @@ gfc_resolve_omp_do_blocks (gfc_code *code, gfc_namespace *ns)
> }
> if (i < omp_current_do_collapse || omp_current_do_collapse <= 0)
> omp_current_do_collapse = 1;
> - if (code->ext.omp_clauses->lists[OMP_LIST_REDUCTION_INSCAN])
> + if (code->op == EXEC_OMP_LOOP)
> + ; /* Already rejected in resolve_omp_clauses. */
I don't understand why is this needed. Sure, the vast majority of
constructs don't allow reduction(inscan, ...), do we need to list them all?
Is EXEC_OMP_LOOP somehow reusing that list for something else? What about
EXEC_OMP_*_LOOP? If not, how does that differ say from EXEC_OMP_DISTRIBUTE
or EXEC_OMP_TASKLOOP and many others?
If it is rejected earlier, then perhaps we should free/clear the list
after we diagnose it if it causes harm later.
> + else if (code->ext.omp_clauses->lists[OMP_LIST_REDUCTION_INSCAN])
> {
> locus *loc
> = &code->ext.omp_clauses->lists[OMP_LIST_REDUCTION_INSCAN]->where;
> @@ -9224,6 +9226,7 @@ gfc_resolve_do_iterator (gfc_code *code, gfc_symbol *sym, bool add_clause)
>
> p = gfc_get_omp_namelist ();
> p->sym = sym;
> + p->where = omp_current_ctx->code->loc;
> p->next = omp_clauses->lists[OMP_LIST_PRIVATE];
> omp_clauses->lists[OMP_LIST_PRIVATE] = p;
> }
Ok.
> diff --git a/gcc/fortran/resolve.cc b/gcc/fortran/resolve.cc
> index 94213cd3cd4..bd2a749776d 100644
> --- a/gcc/fortran/resolve.cc
> +++ b/gcc/fortran/resolve.cc
> @@ -11950,6 +11950,7 @@ gfc_resolve_code (gfc_code *code, gfc_namespace *ns)
> case EXEC_OMP_DISTRIBUTE_SIMD:
> case EXEC_OMP_DO:
> case EXEC_OMP_DO_SIMD:
> + case EXEC_OMP_LOOP:
> case EXEC_OMP_SIMD:
> case EXEC_OMP_TARGET_SIMD:
> gfc_resolve_omp_do_blocks (code, ns);
I'm afraid this is needed but insufficient.
I think
case EXEC_OMP_MASKED_TASKLOOP:
case EXEC_OMP_MASKED_TASKLOOP_SIMD:
case EXEC_OMP_MASTER_TASKLOOP:
case EXEC_OMP_MASTER_TASKLOOP_SIMD:
case EXEC_OMP_PARALLEL_LOOP:
case EXEC_OMP_TARGET_PARALLEL_LOOP:
case EXEC_OMP_TARGET_TEAMS_LOOP:
case EXEC_OMP_TARGET_SIMD:
case EXEC_OMP_TEAMS_LOOP:
should be in the list above (of course alphabetically sorted in between the
others)
gfc_resolve_omp_parallel_blocks (code, ns);
(the non-parallel-workshare one).
Went through the c-family/c-omp.cc list in comment above splitting
function and checked all appropriate constructs there...
> diff --git a/gcc/testsuite/gfortran.dg/gomp/loop-5.f90 b/gcc/testsuite/gfortran.dg/gomp/loop-5.f90
> new file mode 100644
> index 00000000000..1948e782653
> --- /dev/null
> +++ b/gcc/testsuite/gfortran.dg/gomp/loop-5.f90
> @@ -0,0 +1,84 @@
> +! { dg-additional-options "-fdump-tree-original" }
> +!
> +! PR fortran/108512
> +
> +! The problem was that the context wasn't reset for the 'LOOP'
> +! such that the clauses of the loops weren't seen when adding
> +! PRIVATE clauses.
> +!
> +! In the following, only the loop variable of the non-OpenMP loop
> +! in 'subroutine four' should get a front-end addded PRIVATE clause
> +
> +implicit none
> +integer :: x, a(10), b(10), n
> + n = 10
> + a = -42
> + b = [(2*x, x=1,10)]
> +
> +! { dg-final { scan-tree-dump-times "#pragma omp target map\\(tofrom:a\\) map\\(tofrom:b\\) map\\(tofrom:x\\)\[\r\n\]" 1 "original" } }
> +! { dg-final { scan-tree-dump-times "#pragma omp parallel\[\r\n\]" 2 "original" } }
> +! ^- shows up twice; checked only here.
> +! { dg-final { scan-tree-dump-times "#pragma omp loop lastprivate\\(x\\)\[\r\n\]" 1 "original" } }
> +
> + !$omp target parallel map(tofrom: a, b, x)
> + !$omp loop lastprivate(x)
> + DO x = 1, n
> + a(x) = a(x) + b(x)
> + END DO
> + !$omp end loop
> + !$omp end target parallel
> + if (x /= 11) error stop
> + if (any (a /= [(2*x - 42, x=1,10)])) error stop
> + call two()
> + call three()
> + call four()
> +end
> +
> +subroutine two
> + implicit none
> + integer :: ii, mm, arr(10)
> + mm = 10
> + arr = 0
> +
> +! { dg-final { scan-tree-dump-times "#pragma omp target map\\(tofrom:arr\\) map\\(tofrom:ii\\)\[\r\n\]" 1 "original" } }
> +! { dg-final { scan-tree-dump-times "#pragma omp parallel shared\\(ii\\)\[\r\n\]" 1 "original" } }
> +! { dg-final { scan-tree-dump-times "#pragma omp loop lastprivate\\(ii\\)\[\r\n\]" 1 "original" } }
> +
> + !$omp target parallel loop map(tofrom: arr) lastprivate(ii)
> + DO ii = 1, mm
> + arr(ii) = arr(ii) + ii
> + END DO
> +end
> +
> +subroutine three
> + implicit none
> + integer :: kk, zz, var(10)
> + zz = 10
> + var = 0
> +
> +! { dg-final { scan-tree-dump-times "#pragma omp target map\\(tofrom:var\\)\[\r\n\]" 1 "original" } }
> +! "#pragma omp parallel\[\r\n\]" - shows up twice, dump checked above
> +! { dg-final { scan-tree-dump-times "#pragma omp loop\[\r\n\]" 1 "original" } }
> +
> + !$omp target parallel loop map(tofrom: var)
> + DO kk = 1, zz
> + var(kk) = var(kk) + kk
> + END DO
> +end
> +
> +subroutine four
> + implicit none
> + integer :: jj, qq, dist(10)
> + qq = 10
> + dist = 0
> +
> +! { dg-final { scan-tree-dump-times "#pragma omp target map\\(tofrom:dist\\)\[\r\n\]" 1 "original" } }
> +! { dg-final { scan-tree-dump-times "#pragma omp parallel private\\(jj\\)\[\r\n\]" 1 "original" } }
> +
> + !$omp target parallel map(tofrom: dist)
> + ! *no* '!$omp do/loop/simd'
> + DO jj = 1, qq
> + dist(qq) = dist(qq) + qq
> + END DO
> + !$omp end target parallel
> +end
Jakub
OpenMP/Fortran: Fix loop-iter var privatization with !$OMP LOOP [PR108512]
For 'parallel', loop-iteration variables are marked are marked as 'private',
unless they either appear in an omp do/simd loop or an data-sharing clause
already exists for those on 'parallel'. 'omp loop' wasn't handled, leading
to (potentially) multiple data-sharing clauses in gfc_resolve_do_iterator
as omp_current_ctx pointed to the 'parallel' directive, ignoring the
in-betwen 'loop' directive.
The latter lead to a bogus diagnostic - or rather an ICE as the source
location var contained only '\0'.
gcc/fortran/ChangeLog:
PR fortran/108512
* openmp.cc (gfc_resolve_omp_do_blocks): Don't check 'inscan'
restrictions for loop as rejected elsewhere.
(gfc_resolve_do_iterator): Set a source location for added
'private'-clause arguments.
* resolve.cc (gfc_resolve_code): Call gfc_resolve_omp_do_blocks
also for EXEC_OMP_LOOP.
gcc/testsuite/ChangeLog:
PR fortran/108512
* gfortran.dg/gomp/loop-5.f90: New test.
gcc/fortran/openmp.cc | 5 +-
gcc/fortran/resolve.cc | 1 +
gcc/testsuite/gfortran.dg/gomp/loop-5.f90 | 84 +++++++++++++++++++++++++++++++
3 files changed, 89 insertions(+), 1 deletion(-)
@@ -9056,7 +9056,9 @@ gfc_resolve_omp_do_blocks (gfc_code *code, gfc_namespace *ns)
}
if (i < omp_current_do_collapse || omp_current_do_collapse <= 0)
omp_current_do_collapse = 1;
- if (code->ext.omp_clauses->lists[OMP_LIST_REDUCTION_INSCAN])
+ if (code->op == EXEC_OMP_LOOP)
+ ; /* Already rejected in resolve_omp_clauses. */
+ else if (code->ext.omp_clauses->lists[OMP_LIST_REDUCTION_INSCAN])
{
locus *loc
= &code->ext.omp_clauses->lists[OMP_LIST_REDUCTION_INSCAN]->where;
@@ -9224,6 +9226,7 @@ gfc_resolve_do_iterator (gfc_code *code, gfc_symbol *sym, bool add_clause)
p = gfc_get_omp_namelist ();
p->sym = sym;
+ p->where = omp_current_ctx->code->loc;
p->next = omp_clauses->lists[OMP_LIST_PRIVATE];
omp_clauses->lists[OMP_LIST_PRIVATE] = p;
}
@@ -11950,6 +11950,7 @@ gfc_resolve_code (gfc_code *code, gfc_namespace *ns)
case EXEC_OMP_DISTRIBUTE_SIMD:
case EXEC_OMP_DO:
case EXEC_OMP_DO_SIMD:
+ case EXEC_OMP_LOOP:
case EXEC_OMP_SIMD:
case EXEC_OMP_TARGET_SIMD:
gfc_resolve_omp_do_blocks (code, ns);
new file mode 100644
@@ -0,0 +1,84 @@
+! { dg-additional-options "-fdump-tree-original" }
+!
+! PR fortran/108512
+
+! The problem was that the context wasn't reset for the 'LOOP'
+! such that the clauses of the loops weren't seen when adding
+! PRIVATE clauses.
+!
+! In the following, only the loop variable of the non-OpenMP loop
+! in 'subroutine four' should get a front-end addded PRIVATE clause
+
+implicit none
+integer :: x, a(10), b(10), n
+ n = 10
+ a = -42
+ b = [(2*x, x=1,10)]
+
+! { dg-final { scan-tree-dump-times "#pragma omp target map\\(tofrom:a\\) map\\(tofrom:b\\) map\\(tofrom:x\\)\[\r\n\]" 1 "original" } }
+! { dg-final { scan-tree-dump-times "#pragma omp parallel\[\r\n\]" 2 "original" } }
+! ^- shows up twice; checked only here.
+! { dg-final { scan-tree-dump-times "#pragma omp loop lastprivate\\(x\\)\[\r\n\]" 1 "original" } }
+
+ !$omp target parallel map(tofrom: a, b, x)
+ !$omp loop lastprivate(x)
+ DO x = 1, n
+ a(x) = a(x) + b(x)
+ END DO
+ !$omp end loop
+ !$omp end target parallel
+ if (x /= 11) error stop
+ if (any (a /= [(2*x - 42, x=1,10)])) error stop
+ call two()
+ call three()
+ call four()
+end
+
+subroutine two
+ implicit none
+ integer :: ii, mm, arr(10)
+ mm = 10
+ arr = 0
+
+! { dg-final { scan-tree-dump-times "#pragma omp target map\\(tofrom:arr\\) map\\(tofrom:ii\\)\[\r\n\]" 1 "original" } }
+! { dg-final { scan-tree-dump-times "#pragma omp parallel shared\\(ii\\)\[\r\n\]" 1 "original" } }
+! { dg-final { scan-tree-dump-times "#pragma omp loop lastprivate\\(ii\\)\[\r\n\]" 1 "original" } }
+
+ !$omp target parallel loop map(tofrom: arr) lastprivate(ii)
+ DO ii = 1, mm
+ arr(ii) = arr(ii) + ii
+ END DO
+end
+
+subroutine three
+ implicit none
+ integer :: kk, zz, var(10)
+ zz = 10
+ var = 0
+
+! { dg-final { scan-tree-dump-times "#pragma omp target map\\(tofrom:var\\)\[\r\n\]" 1 "original" } }
+! "#pragma omp parallel\[\r\n\]" - shows up twice, dump checked above
+! { dg-final { scan-tree-dump-times "#pragma omp loop\[\r\n\]" 1 "original" } }
+
+ !$omp target parallel loop map(tofrom: var)
+ DO kk = 1, zz
+ var(kk) = var(kk) + kk
+ END DO
+end
+
+subroutine four
+ implicit none
+ integer :: jj, qq, dist(10)
+ qq = 10
+ dist = 0
+
+! { dg-final { scan-tree-dump-times "#pragma omp target map\\(tofrom:dist\\)\[\r\n\]" 1 "original" } }
+! { dg-final { scan-tree-dump-times "#pragma omp parallel private\\(jj\\)\[\r\n\]" 1 "original" } }
+
+ !$omp target parallel map(tofrom: dist)
+ ! *no* '!$omp do/loop/simd'
+ DO jj = 1, qq
+ dist(qq) = dist(qq) + qq
+ END DO
+ !$omp end target parallel
+end