[PATCH] [OPENMP] Do not emit implicit barrier for single directive with 'copyprivate' clause(s).

[Alexey Bataev]

Hi rjmccall, hfinkel,

Runtime function for 'copyprivate' directive generates implicit barriers, so no need to emit it.

http://reviews.llvm.org/D9215

Files:
  lib/CodeGen/CGStmtOpenMP.cpp
  test/OpenMP/single_codegen.cpp

Index: test/OpenMP/single_codegen.cpp
===================================================================
--- test/OpenMP/single_codegen.cpp
+++ test/OpenMP/single_codegen.cpp
@@ -51,13 +51,24 @@
 // CHECK-NEXT:  call void @__kmpc_end_single([[IDENT_T_TY]]* [[DEFAULT_LOC]], i32 [[GTID]])
 // CHECK-NEXT:  br label {{%?}}[[EXIT]]
 // CHECK:       [[EXIT]]
-// CHECK-NOT:   __kmpc_cancel_barrier
+// CHECK-NOT:   call {{.+}} @__kmpc_cancel_barrier
 #pragma omp single nowait
   a = 2;
 // CHECK:       [[RES:%.+]] = call i32 @__kmpc_single([[IDENT_T_TY]]* [[DEFAULT_LOC]], i32 [[GTID]])
 // CHECK-NEXT:  [[IS_SINGLE:%.+]] = icmp ne i32 [[RES]], 0
 // CHECK-NEXT:  br i1 [[IS_SINGLE]], label {{%?}}[[THEN:.+]], label {{%?}}[[EXIT:.+]]
 // CHECK:       [[THEN]]
+// CHECK-NEXT:  store i8 2, i8* [[A_ADDR]]
+// CHECK-NEXT:  call void @__kmpc_end_single([[IDENT_T_TY]]* [[DEFAULT_LOC]], i32 [[GTID]])
+// CHECK-NEXT:  br label {{%?}}[[EXIT]]
+// CHECK:       [[EXIT]]
+// CHECK:       call{{.*}} @__kmpc_cancel_barrier([[IDENT_T_TY]]* [[IMPLICIT_BARRIER_SINGLE_LOC]], i32 [[GTID]])
+#pragma omp single
+  a = 2;
+// CHECK:       [[RES:%.+]] = call i32 @__kmpc_single([[IDENT_T_TY]]* [[DEFAULT_LOC]], i32 [[GTID]])
+// CHECK-NEXT:  [[IS_SINGLE:%.+]] = icmp ne i32 [[RES]], 0
+// CHECK-NEXT:  br i1 [[IS_SINGLE]], label {{%?}}[[THEN:.+]], label {{%?}}[[EXIT:.+]]
+// CHECK:       [[THEN]]
 // CHECK-NEXT:  invoke void [[FOO]]()
 // CHECK:       to label {{%?}}[[CONT:.+]] unwind
 // CHECK:       [[CONT]]
@@ -86,7 +97,7 @@
 // CHECK:       [[COPY_LIST_VOID_PTR:%.+]] = bitcast [5 x i8*]* [[COPY_LIST]] to i8*
 // CHECK:       [[DID_IT_VAL:%.+]] = load i32, i32* [[DID_IT]],
 // CHECK:       call void @__kmpc_copyprivate([[IDENT_T_TY]]* [[DEFAULT_LOC]], i32 [[GTID]], i32 40, i8* [[COPY_LIST_VOID_PTR]], void (i8*, i8*)* [[COPY_FUNC:@.+]], i32 [[DID_IT_VAL]])
-// CHECK:       call{{.*}} @__kmpc_cancel_barrier([[IDENT_T_TY]]* [[IMPLICIT_BARRIER_SINGLE_LOC]], i32 [[GTID]])
+// CHECK-NOT:   call {{.+}} @__kmpc_cancel_barrier
 #pragma omp single copyprivate(a, c, tc, a2, tc2)
   foo();
 // CHECK-NOT:   call i32 @__kmpc_single
Index: lib/CodeGen/CGStmtOpenMP.cpp
===================================================================
--- lib/CodeGen/CGStmtOpenMP.cpp
+++ lib/CodeGen/CGStmtOpenMP.cpp
@@ -1251,8 +1251,9 @@
   CGM.getOpenMPRuntime().emitSingleRegion(*this, CodeGen, S.getLocStart(),
                                           CopyprivateVars, DestExprs, SrcExprs,
                                           AssignmentOps);
-  // Emit an implicit barrier at the end.
-  if (!S.getSingleClause(OMPC_nowait)) {
+  // Emit an implicit barrier at the end (if no 'nowait' clause and no
+  // 'copyprivate' clause).
+  if (!S.getSingleClause(OMPC_nowait) && CopyprivateVars.empty()) {
     CGM.getOpenMPRuntime().emitBarrierCall(*this, S.getLocStart(), OMPD_single);
   }
 }

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