Sync before exiting a cilk_scope with a non-compound statement body

Author: VoxSciurorum

clang/lib/CodeGen/CGCilk.cpp

@@ -456,7 +456,7 @@ void CodeGenFunction::EmitCilkSyncStmt(const CilkSyncStmt &S) {
 void CodeGenFunction::EmitCilkScopeStmt(const CilkScopeStmt &S) {
   LexicalScope CilkScope(*this, S.getSourceRange());
 
-  // If this _Cilk_scope is outermost in the function, emit
+  // If this cilk_scope is outermost in the function, emit
   // tapir_runtime_{start,end} intrinsics around the scope.
   bool ThisScopeIsOutermost = false;
   if (!WithinCilkScope) {
@@ -471,22 +471,24 @@ void CodeGenFunction::EmitCilkScopeStmt(const CilkScopeStmt &S) {
     if (ThisScopeIsOutermost && !CurSyncRegion) {
       llvm::Instruction *TapirRTStart = Builder.CreateCall(
           CGM.getIntrinsic(llvm::Intrinsic::tapir_runtime_start));
-      // Mark the end of the _Cilk_scope with tapir_runtime_end.
+      // Mark the end of the cilk_scope with tapir_runtime_end.
       EHStack.pushCleanup<TapirRuntimeEndCleanup>(NormalAndEHCleanup,
                                                   TapirRTStart);
     }
     // Create a nested synced scope.
-    SyncRegionRAII SyncReg(*this);
-    bool BodyIsCompoundStmt = isa<CompoundStmt>(S.getBody());
-    if (BodyIsCompoundStmt)
+    if (isa<CompoundStmt>(S.getBody())) {
+      SyncRegionRAII SyncReg(*this);
       ScopeIsSynced = true;
-
-    // Emit the spawned statement.
-    EmitStmt(S.getBody());
+      EmitStmt(S.getBody());
+    } else {
+      PushSyncRegion()->addImplicitSync();
+      EmitStmt(S.getBody());
+      PopSyncRegion();
+    }
   }
 
-  // If this _Cilk_scope is outermost in the function, mark that CodeGen is no
-  // longer emitting within a _Cilk_scope.
+  // If this cilk_scope is outermost in the function, mark that CodeGen is no
+  // longer emitting within a cilk_scope.
   if (ThisScopeIsOutermost)
     WithinCilkScope = false;
 }

clang/test/Cilk/scope-nobrace.c

@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -emit-llvm -fopencilk -disable-llvm-passes -O1 -x c %s -o - | FileCheck %s
+
+extern void bbb(void);
+
+// CHECK-LABEL: @aaa
+int aaa(int argc, char *argv[])
+{
+// CHECK: call token @llvm.tapir.runtime.start()
+  cilk_scope
+    for (int i = 0; i < argc; ++i)
+// CHECK: detach within
+// CHECK: call void @bbb
+// CHECK-NEXT: reattach within
+// sync must precede runtime end
+// CHECK: sync within
+// CHECK: call void @llvm.tapir.runtime.end
+      cilk_spawn { bbb(); }
+  return 0;
+}