Hi!
On 2026-06-23T19:51:49+0200, Paul-Antoine Arras <[email protected]> wrote:
> For the `omp master' and `omp masked filter(x)' constructs, the compiler
> lowers
> the filter check by emitting omp_get_thread_num() == filter. Because
> omp_get_thread_num is a public OpenMP API function, OMPT cannot distinguish
> this
> internal check from a user-level thread-number query.
>
> Introduce GOMP_has_masked_thread_num(int tid), a new libgomp entry point that
> encapsulates the thread id check, and update lower_omp_master to call it
> instead
> of building the comparison inline.
The C++ complains:
[...]/libgomp/parallel.cc: In function ‘bool
GOMP_has_masked_thread_num(int)’:
[...]/libgomp/parallel.cc:445:14: error: comparison of integer expressions
of different signedness: ‘int’ and ‘unsigned int’ [-Werror=sign-compare]
445 | return tid == gomp_thread ()->ts.team_id;
| ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Is the correct/preferable fix to change the 'GOMP_has_masked_thread_num'
API (that is, 'unsigned kind'), or cast locally (which expression?)?
Grüße
Thomas
> gcc/ChangeLog:
>
> * omp-builtins.def (BUILT_IN_GOMP_HAS_MASKED_THREAD_NUM): New builtin.
> * omp-low.cc (lower_omp_master): Call it.
>
> libgomp/ChangeLog:
>
> * libgomp.map (GOMP_6.0.2): New symbol version. Export
> GOMP_has_masked_thread_num.
> * libgomp_g.h (GOMP_has_masked_thread_num): New declaration.
> * parallel.c (GOMP_has_masked_thread_num): New function.
>
> gcc/testsuite/ChangeLog:
>
> * c-c++-common/gomp/masked-1.c: Add scan directives verifying that
> GOMP_has_masked_thread_num is emitted and omp_get_thread_num is not.
> * g++.dg/gomp/master-3.C: Update scan-tree-dump-times to look for
> GOMP_has_masked_thread_num instead of omp_get_thread_num.
> * gcc.dg/gomp/master-3.c: Likewise.
> * gfortran.dg/gomp/masked-1.f90: Add scan directive for
> GOMP_has_masked_thread_num.
> ---
> gcc/omp-builtins.def | 3 +++
> gcc/omp-low.cc | 5 ++---
> gcc/testsuite/c-c++-common/gomp/masked-1.c | 6 ++++++
> gcc/testsuite/g++.dg/gomp/master-3.C | 2 +-
> gcc/testsuite/gcc.dg/gomp/master-3.c | 2 +-
> gcc/testsuite/gfortran.dg/gomp/masked-1.f90 | 6 +++++-
> libgomp/libgomp.map | 5 +++++
> libgomp/libgomp_g.h | 1 +
> libgomp/parallel.c | 9 +++++++++
> 9 files changed, 33 insertions(+), 6 deletions(-)
>
> diff --git a/gcc/omp-builtins.def b/gcc/omp-builtins.def
> index f5b16c5d29e..c7ddea9880a 100644
> --- a/gcc/omp-builtins.def
> +++ b/gcc/omp-builtins.def
> @@ -496,3 +496,6 @@ DEF_GOMP_BUILTIN (BUILT_IN_GOMP_WARNING, "GOMP_warning",
> BT_FN_VOID_CONST_PTR_SIZE, ATTR_NOTHROW_LEAF_LIST)
> DEF_GOMP_BUILTIN (BUILT_IN_GOMP_ERROR, "GOMP_error",
> BT_FN_VOID_CONST_PTR_SIZE,
> ATTR_COLD_NORETURN_NOTHROW_LEAF_LIST)
> +DEF_GOMP_BUILTIN (BUILT_IN_GOMP_HAS_MASKED_THREAD_NUM,
> + "GOMP_has_masked_thread_num", BT_FN_BOOL_INT,
> + ATTR_CONST_NOTHROW_LEAF_LIST)
> diff --git a/gcc/omp-low.cc b/gcc/omp-low.cc
> index eef0b418b9b..e067267cede 100644
> --- a/gcc/omp-low.cc
> +++ b/gcc/omp-low.cc
> @@ -9068,9 +9068,8 @@ lower_omp_master (gimple_stmt_iterator *gsi_p,
> omp_context *ctx)
> gsi_replace (gsi_p, bind, true);
> gimple_bind_add_stmt (bind, stmt);
>
> - bfn_decl = builtin_decl_explicit (BUILT_IN_OMP_GET_THREAD_NUM);
> - x = build_call_expr_loc (loc, bfn_decl, 0);
> - x = build2 (EQ_EXPR, boolean_type_node, x, filter);
> + bfn_decl = builtin_decl_explicit (BUILT_IN_GOMP_HAS_MASKED_THREAD_NUM);
> + x = build_call_expr_loc (loc, bfn_decl, 1, filter);
> x = build3 (COND_EXPR, void_type_node, x, NULL, build_and_jump (&lab));
> tseq = NULL;
> gimplify_and_add (x, &tseq);
> diff --git a/gcc/testsuite/c-c++-common/gomp/masked-1.c
> b/gcc/testsuite/c-c++-common/gomp/masked-1.c
> index 36c2e492892..8de87b551e3 100644
> --- a/gcc/testsuite/c-c++-common/gomp/masked-1.c
> +++ b/gcc/testsuite/c-c++-common/gomp/masked-1.c
> @@ -1,3 +1,6 @@
> +/* { dg-do compile } */
> +/* { dg-additional-options "-fdump-tree-omplower" } */
> +
> void bar (void);
>
> void
> @@ -21,3 +24,6 @@ foo (int x, int *a)
> #pragma omp masked filter (x)
> ;
> }
> +
> +/* { dg-final { scan-tree-dump "GOMP_has_masked_thread_num" "omplower" } } */
> +/* { dg-final { scan-tree-dump-not "omp_get_thread_num" "omplower" } } */
> diff --git a/gcc/testsuite/g++.dg/gomp/master-3.C
> b/gcc/testsuite/g++.dg/gomp/master-3.C
> index c396128afdb..3d27b936d64 100644
> --- a/gcc/testsuite/g++.dg/gomp/master-3.C
> +++ b/gcc/testsuite/g++.dg/gomp/master-3.C
> @@ -9,4 +9,4 @@ void foo (void)
> bar(0);
> }
>
> -/* { dg-final { scan-tree-dump-times "omp_get_thread_num" 1 "omplower" } } */
> +/* { dg-final { scan-tree-dump-times "GOMP_has_masked_thread_num" 1
> "omplower" } } */
> diff --git a/gcc/testsuite/gcc.dg/gomp/master-3.c
> b/gcc/testsuite/gcc.dg/gomp/master-3.c
> index 5c0544dfa3c..0d5836748ce 100644
> --- a/gcc/testsuite/gcc.dg/gomp/master-3.c
> +++ b/gcc/testsuite/gcc.dg/gomp/master-3.c
> @@ -9,4 +9,4 @@ void foo (void)
> bar(0);
> }
>
> -/* { dg-final { scan-tree-dump-times "omp_get_thread_num" 1 "ompexp" } } */
> +/* { dg-final { scan-tree-dump-times "GOMP_has_masked_thread_num" 1 "ompexp"
> } } */
> diff --git a/gcc/testsuite/gfortran.dg/gomp/masked-1.f90
> b/gcc/testsuite/gfortran.dg/gomp/masked-1.f90
> index 1bd61760ced..2b2526ac712 100644
> --- a/gcc/testsuite/gfortran.dg/gomp/masked-1.f90
> +++ b/gcc/testsuite/gfortran.dg/gomp/masked-1.f90
> @@ -1,4 +1,6 @@
> -! { dg-additional-options "-ffree-line-length-none" }
> +! { dg-do compile }
> +! { dg-additional-options "-ffree-line-length-none -fdump-tree-omplower" }
> +
> subroutine foo (x, a)
> implicit none
> integer, value :: x
> @@ -92,3 +94,5 @@ subroutine foobar (d, f, fi, p, s, g, i1, i2, l, ll, nth,
> ntm, pp, q, r, r2)
> end do
> !$omp end parallel masked taskloop simd
> end subroutine
> +
> +! { dg-final { scan-tree-dump "GOMP_has_masked_thread_num" "omplower" } }
> diff --git a/libgomp/libgomp.map b/libgomp/libgomp.map
> index dbde88c4d5f..5faeb27b74b 100644
> --- a/libgomp/libgomp.map
> +++ b/libgomp/libgomp.map
> @@ -482,6 +482,11 @@ GOMP_6.0.1 {
> omp_target_memset_async;
> } GOMP_6.0;
>
> +GOMP_6.0.2 {
> + global:
> + GOMP_has_masked_thread_num;
> +} GOMP_6.0.1;
> +
> OACC_2.0 {
> global:
> acc_get_num_devices;
> diff --git a/libgomp/libgomp_g.h b/libgomp/libgomp_g.h
> index 761c9bd594b..d36d9d36020 100644
> --- a/libgomp/libgomp_g.h
> +++ b/libgomp/libgomp_g.h
> @@ -293,6 +293,7 @@ extern unsigned GOMP_parallel_reductions (void (*) (void
> *), void *, unsigned,
> unsigned);
> extern bool GOMP_cancel (int, bool);
> extern bool GOMP_cancellation_point (int);
> +extern bool GOMP_has_masked_thread_num (int);
>
> /* task.c */
>
> diff --git a/libgomp/parallel.c b/libgomp/parallel.c
> index fe7939ddcce..175554de4c9 100644
> --- a/libgomp/parallel.c
> +++ b/libgomp/parallel.c
> @@ -270,6 +270,15 @@ GOMP_cancel (int which, bool do_cancel)
> gomp_team_barrier_cancel (team);
> return true;
> }
> +
> +/* Return true if the current thread number equals TID.
> + Used to implement the masked construct's filter clause. */
> +
> +bool
> +GOMP_has_masked_thread_num (int tid)
> +{
> + return tid == gomp_thread ()->ts.team_id;
> +}
>
> /* The public OpenMP API for thread and team related inquiries. */
>
> --
> 2.53.0
