[flang-commits] [flang] [Flang][Openmp]Prevent TODO abort on nothing directive (PR #202679)

[via flang-commits]

https://github.com/ShashwathiNavada created https://github.com/llvm/llvm-project/pull/202679

Since nothing is a no-op directive (OpenMP 5.2, 8.4), handle it during lowering instead of falling through to the generic unimplemented utility-directive path and triggering a TODO abort.

>From c1a2aacefdc7f7f7e24414425ec884a294046b9b Mon Sep 17 00:00:00 2001
From: ShashwathiNavada <shashwathinavada at gmail.com>
Date: Tue, 9 Jun 2026 09:43:37 -0500
Subject: [PATCH] [Flang][Openmp]Prevent TODO abort on nothing directive

---
 flang/lib/Lower/OpenMP/OpenMP.cpp   | 15 ++++++++++++---
 flang/test/Lower/OpenMP/nothing.f90 |  8 ++++++++
 2 files changed, 20 insertions(+), 3 deletions(-)
 create mode 100644 flang/test/Lower/OpenMP/nothing.f90

diff --git a/flang/lib/Lower/OpenMP/OpenMP.cpp b/flang/lib/Lower/OpenMP/OpenMP.cpp
index 266b06f353675..f4c46ed238dcb 100644
--- a/flang/lib/Lower/OpenMP/OpenMP.cpp
+++ b/flang/lib/Lower/OpenMP/OpenMP.cpp
@@ -4899,9 +4899,18 @@ static void genOMP(lower::AbstractConverter &converter, lower::SymMap &symTable,
 static void genOMP(lower::AbstractConverter &converter, lower::SymMap &symTable,
                    semantics::SemanticsContext &semaCtx,
                    lower::pft::Evaluation &eval,
-                   const parser::OmpUtilityDirective &) {
-  if (!semaCtx.langOptions().OpenMPSimd)
-    TODO(converter.getCurrentLocation(), "OmpUtilityDirective");
+                   const parser::OmpUtilityDirective &dir) {
+  common::visit(
+      common::visitors{
+          [&](const parser::OmpNothingDirective &) {
+            // nothing-directive is a no-op (OpenMP 5.2 [8.4])
+          },
+          [&](const parser::OmpErrorDirective &) {
+            if (!semaCtx.langOptions().OpenMPSimd)
+              TODO(converter.getCurrentLocation(), "OmpErrorDirective");
+          },
+      },
+      dir.u);
 }
 
 static void genOMP(lower::AbstractConverter &converter, lower::SymMap &symTable,
diff --git a/flang/test/Lower/OpenMP/nothing.f90 b/flang/test/Lower/OpenMP/nothing.f90
new file mode 100644
index 0000000000000..775b6a34db45e
--- /dev/null
+++ b/flang/test/Lower/OpenMP/nothing.f90
@@ -0,0 +1,8 @@
+!RUN: %flang_fc1 -emit-hlfir -fopenmp -fopenmp-version=52 %s -o - | FileCheck %s
+!RUN: bbc -emit-hlfir -fopenmp -fopenmp-version=52 %s -o - | FileCheck %s
+
+! CHECK-LABEL: func @_QPfoo
+subroutine foo
+  ! CHECK-NOT: omp.
+  !$omp nothing
+end subroutine