[OpenMP] New Clang tests for 'taskgraph' directive

This patch adds two simple tests for parsing/serialization/deserialization
and codegen for the OpenMP 'taskgraph' directive (for the current
record-and-replay based implementation).

Author: jtb20

clang/test/OpenMP/taskgraph_ast_print.cpp

@@ -0,0 +1,31 @@
+// RUN: %clang_cc1 -verify -fopenmp -ast-print %s | FileCheck %s
+// RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -emit-pch -o %t %s
+// RUN: %clang_cc1 -fopenmp -std=c++11 -include-pch %t -verify %s -ast-print | FileCheck %s
+// expected-no-diagnostics
+
+#ifndef HEADER
+#define HEADER
+
+int main() {
+  int x = 0, y = 0;
+
+#pragma omp taskgraph
+// CHECK: #pragma omp taskgraph
+  {
+#pragma omp task depend(in: x) depend(out: y)
+// CHECK: #pragma omp task depend(in : x) depend(out : y)
+    {
+      y = x;
+    }
+#pragma omp task depend(inout: x, y)
+// CHECK: #pragma omp task depend(inout : x,y)
+    {
+      x++;
+      y++;
+    }
+  }
+
+  return 0;
+}
+
+#endif

clang/test/OpenMP/taskgraph_codegen.cpp

@@ -0,0 +1,52 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --functions "main" --replace-value-regex "[0-9][0-9][0-9]+" --prefix-filecheck-ir-name _
+
+// FIXME: The hash used to identify taskgraph regions (the fourth argument of
+// __kmpc_taskgraph) is unstable between the two compiler invocations below,
+// and furthermore is a little hard to identify with update_cc_test_checks.py.
+// The above works for now, but it's not ideal.
+
+// RUN: %clang_cc1 -verify -fopenmp -x c++ -triple x86_64-unknown-unknown -emit-llvm %s -fexceptions -fcxx-exceptions -o - | FileCheck %s
+// RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -triple x86_64-unknown-unknown -fexceptions -fcxx-exceptions -emit-pch -o %t %s
+// RUN: %clang_cc1 -fopenmp -x c++ -triple x86_64-unknown-unknown -fexceptions -fcxx-exceptions -std=c++11 -include-pch %t -verify %s -emit-llvm -o - | FileCheck %s
+// expected-no-diagnostics
+
+#ifndef HEADER
+#define HEADER
+
+// CHECK-LABEL: @main(
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    [[RETVAL:%.*]] = alloca i32, align 4
+// CHECK-NEXT:    [[X:%.*]] = alloca i32, align 4
+// CHECK-NEXT:    [[Y:%.*]] = alloca i32, align 4
+// CHECK-NEXT:    [[AGG_CAPTURED:%.*]] = alloca [[STRUCT_ANON:%.*]], align 8
+// CHECK-NEXT:    [[TMP0:%.*]] = call i32 @__kmpc_global_thread_num(ptr @[[GLOB1:[0-9]+]])
+// CHECK-NEXT:    store i32 0, ptr [[RETVAL]], align 4
+// CHECK-NEXT:    store i32 0, ptr [[X]], align 4
+// CHECK-NEXT:    store i32 0, ptr [[Y]], align 4
+// CHECK-NEXT:    [[TMP1:%.*]] = getelementptr inbounds nuw [[STRUCT_ANON]], ptr [[AGG_CAPTURED]], i32 0, i32 0
+// CHECK-NEXT:    store ptr [[X]], ptr [[TMP1]], align 8
+// CHECK-NEXT:    [[TMP2:%.*]] = getelementptr inbounds nuw [[STRUCT_ANON]], ptr [[AGG_CAPTURED]], i32 0, i32 1
+// CHECK-NEXT:    store ptr [[Y]], ptr [[TMP2]], align 8
+// CHECK-NEXT:    call void @__kmpc_taskgraph(ptr @[[GLOB1]], i32 [[TMP0]], i32 0, i32 {{[0-9][0-9][0-9]+}}, ptr @taskgraph.omp_outlined., ptr [[AGG_CAPTURED]])
+// CHECK-NEXT:    ret i32 0
+//
+int main() {
+  int x = 0, y = 0;
+
+#pragma omp taskgraph
+  {
+#pragma omp task depend(in: x) depend(out: y)
+    {
+      y = x;
+    }
+#pragma omp task depend(inout: x, y)
+    {
+      x++;
+      y++;
+    }
+  }
+
+  return 0;
+}
+
+#endif