[DebugInfo] Mark OpenMP generated functions as artificial

[alok]

Summary

The OpenMP generates many functions which are not in user program.

Example: "captured_stmt_debug_", "captured_stmt", ".omp_outlined._debug__",
".omp_task_entry.", ".omp_outlined.", ".omp_outlined..1"

Current patch marks these all as artificial.

[djtodoro]

This looks reasonable to me.

[dblaikie]

Might not hurt to have some negative test cases too - like something that is a VarDecl but has NoStub DynamicInitKind?

[alok]

Re-based and updated to include one negative testcase.
I could not find a test for VarDecl with DynamicInitKind::NoStub. There are constructors for other DynamicInitKind but not for NoStub. Please help me in case you are aware of the condition when it is produced.

[dblaikie]

In D111521#3584439, @alok wrote:

Re-based and updated to include one negative testcase.
I could not find a test for VarDecl with DynamicInitKind::NoStub. There are constructors for other DynamicInitKind but not for NoStub. Please help me in case you are aware of the condition when it is produced.

I've got no particular knowledge of OpenMP unfortunately - the suggestion was based on looking at the conditions in the code & wanting them to all be tested.

If it can't be tested, could the test in the code be replaced with an assertion that it never happens?

[alok]

Re-based and updated to incorporate comments from @dblaikie

clang/lib/CodeGen/CGDebugInfo.cpp

if (isa<BlockDecl>(D))
       LinkageName = Name;
 
     Flags |= llvm::DINode::FlagPrototyped;
   }
   if (Name.startswith("\01"))
     Name = Name.substr(1);
 
   if (!HasDecl || D->isImplicit() || D->hasAttr<ArtificialAttr>() ||
-      (isa<VarDecl>(D) && GD.getDynamicInitKind() != DynamicInitKind::NoStub)) {
+      (isa<VarDecl>(D) && GD.getDynamicInitKind() != DynamicInitKind::NoStub) ||
+      isa<CapturedDecl>(D)) {
     Flags |= llvm::DINode::FlagArtificial;
     // Artificial functions should not silently reuse CurLoc.
     CurLoc = SourceLocation();
   }
 
   if (CurFuncIsThunk)
     Flags |= llvm::DINode::FlagThunk;
 

clang/test/OpenMP/outlined_artificial.c

+// This testcase checks emission of DIFlagArtificial flag for outlined
+// subroutines generated by compiler.
+
+// REQUIRES: x86_64-linux
+
+// RUN: %clang_cc1 -debug-info-kind=constructor -x c -verify -triple x86_64-pc-linux-gnu -fopenmp -emit-llvm %s -o - | FileCheck %s
+// expected-no-diagnostics
+
+#if defined(_WIN32)
+#define __KAI_KMPC_CONVENTION __cdecl
+#else
+#define __KAI_KMPC_CONVENTION
+#endif
+
+extern int printf(const char *, ...);
+extern void __KAI_KMPC_CONVENTION omp_set_num_threads(int);
+extern int __KAI_KMPC_CONVENTION omp_get_thread_num(void);
+
+#define N 10
+
+float f[10];
+void foo_simd(int low, int up) {
+  for (int i = low; i < up; ++i) {
+    f[i] = 0.0;
+#pragma omp ordered simd
+    f[i] = 1.0;
+  }
+}
+
+int main() {
+  int arr[10];
+  int i;
+  omp_set_num_threads(2);
+#pragma omp parallel
+#pragma omp single
+#pragma omp taskloop num_tasks(10)
+  for (i = 0; i < N; i++) {
+    arr[i] = i * i;
+  }
+
+  for (int j = 0; j < N; j++) {
+    printf("%d\n", arr[j]);
+  }
+  return 0;
+}
+
+// foo_simd is not artificial.
+// CHECK-DAG: !DISubprogram(name: "foo_simd"
+// CHECK-DAG-SAME: flags: DIFlagPrototyped,
+
+// CHECK-DAG: !DISubprogram(name: "__captured_stmt_debug__"
+// CHECK-DAG-SAME: flags: DIFlagArtificial
+
+// CHECK-DAG: !DISubprogram(name: "__captured_stmt"
+// CHECK-DAG-SAME: flags: DIFlagArtificial
+
+// CHECK-DAG: !DISubprogram(name: ".omp_outlined._debug__"
+// CHECK-DAG-SAME: flags: DIFlagArtificial
+
+// CHECK-DAG: !DISubprogram(linkageName: ".omp_task_entry."
+// CHECK-DAG-SAME: flags: DIFlagArtificial
+
+// CHECK-DAG: !DISubprogram(name: ".omp_outlined."
+// CHECK-DAG-SAME: flags: DIFlagArtificial
+
+// CHECK-DAG: !DISubprogram(name: ".omp_outlined..1"
+// CHECK-DAG-SAME: flags: DIFlagArtificial