[gcc/devel/omp/gcc-16] openmp: Add GOMP_has_masked_thread_num

https://gcc.gnu.org/g:6710ce2f70e381424696010b3cb2f5a8fad2cc74

commit 6710ce2f70e381424696010b3cb2f5a8fad2cc74
Author: Paul-Antoine Arras <[email protected]>
Date:   Tue Jun 16 17:54:54 2026 +0200

    openmp: Add GOMP_has_masked_thread_num
    
    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.
    
    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.
    
    (cherry picked from commit 37c96bf08325bf40edd18e4985ce560e13a80e95)

Diff:
---
 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 f5b16c5d29e6..c7ddea9880ad 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 d0be7989cf53..bd15defd40e6 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 36c2e4928923..8de87b551e30 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 c396128afdb0..3d27b936d64d 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 5c0544dfa3cd..0d5836748ce8 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 1bd61760ced2..2b2526ac7127 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 dbde88c4d5f5..5faeb27b74b0 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 761c9bd594b9..d36d9d360204 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 fe7939ddcce2..175554de4c9a 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.  */