[clang-tidy] openmp-use-default-none - a new check

Summary:
Finds OpenMP directives that are allowed to contain `default` clause,
but either don't specify it, or the clause is specified but with the kind
other than `none`, and suggests to use `default(none)` clause.

Using `default(none)` clause changes the default variable visibility from
being implicitly determined, and thus forces developer to be explicit about the
desired data scoping for each variable.

Reviewers: JonasToth, aaron.ballman, xazax.hun, hokein, gribozavr

Reviewed By: JonasToth, aaron.ballman

Subscribers: jdoerfert, openmp-commits, klimek, sbenza, arphaman, Eugene.Zelenko, ABataev, mgorny, rnkovacs, guansong, cfe-commits

Tags: #clang-tools-extra, #openmp, #clang

Differential Revision: https://reviews.llvm.org/D57113

llvm-svn: 356801

1 files changed, 160 insertions, 0 deletions

diff --git a/clang-tools-extra/test/clang-tidy/openmp-use-default-none.cpp b/clang-tools-extra/test/clang-tidy/openmp-use-default-none.cpp
new file mode 100644
index 00000000000..1a374bde94a
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/openmp-use-default-none.cpp
@@ -0,0 +1,160 @@
+// RUN: %check_clang_tidy %s openmp-use-default-none %t -- -- -x c++ -fopenmp=libomp -fopenmp-version=40
+// RUN: %check_clang_tidy %s openmp-use-default-none %t -- -- -x c   -fopenmp=libomp -fopenmp-version=40
+
+//----------------------------------------------------------------------------//
+// Null cases.
+//----------------------------------------------------------------------------//
+
+// 'for' directive can not have 'default' clause, no diagnostics.
+void n0(const int a) {
+#pragma omp for
+  for (int b = 0; b < a; b++)
+    ;
+}
+
+//----------------------------------------------------------------------------//
+// Single-directive positive cases.
+//----------------------------------------------------------------------------//
+
+// 'parallel' directive.
+
+// 'parallel' directive can have 'default' clause, but said clause is not
+// specified, diagnosed.
+void p0_0() {
+#pragma omp parallel
+  ;
+  // CHECK-NOTES: :[[@LINE-2]]:9: warning: OpenMP directive 'parallel' does not specify 'default' clause, consider specifying 'default(none)' clause
+}
+
+// 'parallel' directive can have 'default' clause, and said clause specified,
+// with 'none' kind, all good.
+void p0_1() {
+#pragma omp parallel default(none)
+  ;
+}
+
+// 'parallel' directive can have 'default' clause, and said clause specified,
+// but with 'shared' kind, which is not 'none', diagnose.
+void p0_2() {
+#pragma omp parallel default(shared)
+  ;
+  // CHECK-NOTES: :[[@LINE-2]]:9: warning: OpenMP directive 'parallel' specifies 'default(shared)' clause, consider using 'default(none)' clause instead
+  // CHECK-NOTES: :[[@LINE-3]]:22: note: existing 'default' clause specified here
+}
+
+// 'task' directive.
+
+// 'task' directive can have 'default' clause, but said clause is not
+// specified, diagnosed.
+void p1_0() {
+#pragma omp task
+  ;
+  // CHECK-NOTES: :[[@LINE-2]]:9: warning: OpenMP directive 'task' does not specify 'default' clause, consider specifying 'default(none)' clause
+}
+
+// 'task' directive can have 'default' clause, and said clause specified,
+// with 'none' kind, all good.
+void p1_1() {
+#pragma omp task default(none)
+  ;
+}
+
+// 'task' directive can have 'default' clause, and said clause specified,
+// but with 'shared' kind, which is not 'none', diagnose.
+void p1_2() {
+#pragma omp task default(shared)
+  ;
+  // CHECK-NOTES: :[[@LINE-2]]:9: warning: OpenMP directive 'task' specifies 'default(shared)' clause, consider using 'default(none)' clause instead
+  // CHECK-NOTES: :[[@LINE-3]]:18: note: existing 'default' clause specified here
+}
+
+// 'teams' directive. (has to be inside of 'target' directive)
+
+// 'teams' directive can have 'default' clause, but said clause is not
+// specified, diagnosed.
+void p2_0() {
+#pragma omp target
+#pragma omp teams
+  ;
+  // CHECK-NOTES: :[[@LINE-2]]:9: warning: OpenMP directive 'teams' does not specify 'default' clause, consider specifying 'default(none)' clause
+}
+
+// 'teams' directive can have 'default' clause, and said clause specified,
+// with 'none' kind, all good.
+void p2_1() {
+#pragma omp target
+#pragma omp teams default(none)
+  ;
+}
+
+// 'teams' directive can have 'default' clause, and said clause specified,
+// but with 'shared' kind, which is not 'none', diagnose.
+void p2_2() {
+#pragma omp target
+#pragma omp teams default(shared)
+  ;
+  // CHECK-NOTES: :[[@LINE-2]]:9: warning: OpenMP directive 'teams' specifies 'default(shared)' clause, consider using 'default(none)' clause instead
+  // CHECK-NOTES: :[[@LINE-3]]:19: note: existing 'default' clause specified here
+}
+
+// 'taskloop' directive.
+
+// 'taskloop' directive can have 'default' clause, but said clause is not
+// specified, diagnosed.
+void p3_0(const int a) {
+#pragma omp taskloop
+  for (int b = 0; b < a; b++)
+    ;
+  // CHECK-NOTES: :[[@LINE-3]]:9: warning: OpenMP directive 'taskloop' does not specify 'default' clause, consider specifying 'default(none)' clause
+}
+
+// 'taskloop' directive can have 'default' clause, and said clause specified,
+// with 'none' kind, all good.
+void p3_1(const int a) {
+#pragma omp taskloop default(none) shared(a)
+  for (int b = 0; b < a; b++)
+    ;
+}
+
+// 'taskloop' directive can have 'default' clause, and said clause specified,
+// but with 'shared' kind, which is not 'none', diagnose.
+void p3_2(const int a) {
+#pragma omp taskloop default(shared)
+  for (int b = 0; b < a; b++)
+    ;
+  // CHECK-NOTES: :[[@LINE-3]]:9: warning: OpenMP directive 'taskloop' specifies 'default(shared)' clause, consider using 'default(none)' clause instead
+  // CHECK-NOTES: :[[@LINE-4]]:22: note: existing 'default' clause specified here
+}
+
+//----------------------------------------------------------------------------//
+// Combined directives.
+// Let's not test every single possible permutation/combination of directives,
+// but just *one* combined directive. The rest will be the same.
+//----------------------------------------------------------------------------//
+
+// 'parallel' directive can have 'default' clause, but said clause is not
+// specified, diagnosed.
+void p4_0(const int a) {
+#pragma omp parallel for
+  for (int b = 0; b < a; b++)
+    ;
+  // CHECK-NOTES: :[[@LINE-3]]:9: warning: OpenMP directive 'parallel for' does not specify 'default' clause, consider specifying 'default(none)' clause
+}
+
+// 'parallel' directive can have 'default' clause, and said clause specified,
+// with 'none' kind, all good.
+void p4_1(const int a) {
+#pragma omp parallel for default(none) shared(a)
+  for (int b = 0; b < a; b++)
+    ;
+}
+
+// 'parallel' directive can have 'default' clause, and said clause specified,
+// but with 'shared' kind, which is not 'none', diagnose.
+void p4_2(const int a) {
+#pragma omp parallel for default(shared)
+  for (int b = 0; b < a; b++)
+    ;
+  // CHECK-NOTES: :[[@LINE-3]]:9: warning: OpenMP directive 'parallel for' specifies 'default(shared)' clause, consider using 'default(none)' clause instead
+  // CHECK-NOTES: :[[@LINE-4]]:26: note: existing 'default' clause specified here
+}