Fix double destruction of objects when OpenMP construct is canceled

[mikerice]

Summary

When an omp for loop is canceled the constructed objects are being destructed twice.

It looks like the desired code is:

{

Obj o;
If (cancelled) branch-through-cleanups to cancel.exit.

}
[cleanups]
cancel.exit:

__kmpc_for_static_fini
br cancel.cont (*)

cancel.cont:

__kmpc_barrier
return

The problem seems to be the branch to cancel.cont is currently also going through the cleanups calling them again. This change just does a direct branch instead.

[ABataev]

LG

cfe/trunk/lib/CodeGen/CodeGenFunction.h

void emitExit(CodeGenFunction &CGF, OpenMPDirectiveKind Kind,
                   const llvm::function_ref<void(CodeGenFunction &)> &CodeGen) {
       if (Stack.back().Kind == Kind && getExitBlock().isValid()) {
         assert(CGF.getOMPCancelDestination(Kind).isValid());
         assert(CGF.HaveInsertPoint());
         assert(!Stack.back().HasBeenEmitted);
         auto IP = CGF.Builder.saveAndClearIP();
         CGF.EmitBlock(Stack.back().ExitBlock.getBlock());
         CodeGen(CGF);
-        CGF.EmitBranchThroughCleanup(Stack.back().ContBlock);
+        CGF.EmitBranch(Stack.back().ContBlock.getBlock());
         CGF.Builder.restoreIP(IP);
         Stack.back().HasBeenEmitted = true;
       }
       CodeGen(CGF);
     }
     /// Enter the cancel supporting \a Kind construct.
     /// \param Kind OpenMP directive that supports cancel constructs.
     /// \param HasCancel true, if the construct has inner cancel directive,

cfe/trunk/test/OpenMP/cancel_codegen_cleanup.cpp

+// RUN: %clang_cc1 -std=c++11 -fopenmp -fopenmp-version=45 -triple x86_64-apple-darwin13.4.0 -emit-llvm -o - %s | FileCheck %s
+
+//CHECK: call i32 @__kmpc_cancel
+//CHECK: br {{.*}}label %[[EXIT:[^,].+]], label %[[CONTINUE:.+]]
+//CHECK: [[EXIT]]:
+//CHECK: store i32 [[EXIT_SLOT:[0-9]+]]
+//CHECK: br label %[[CLEANUP:.+]]
+//CHECK: [[CONTINUE]]:
+//CHECK: store i32 [[CONT_SLOT:[0-9]+]],
+//CHECK: br label %[[CLEANUP]]
+//CHECK: [[CLEANUP]]:
+//CHECK-NEXT: call void @_ZN3ObjD1Ev
+//CHECK: switch i32{{.*}}, label %[[UNREACHABLE:.+]] [
+//CHECK:   i32 [[CONT_SLOT]], label %[[CLEANUPCONT:.+]]
+//CHECK:   i32 [[EXIT_SLOT]], label %[[CANCELEXIT:.+]]
+//CHECK-NEXT: ]
+//CHECK: [[CLEANUPCONT]]:
+//CHECK: br label %[[CANCELCONT:.+]]
+//CHECK: [[CANCELCONT]]:
+//CHECK-NEXT: call void @__kmpc_barrier(
+//CHECK-NEXT: ret void
+//CHECK: [[UNREACHABLE]]:
+//CHECK-NEXT: unreachable
+//CHECK-NEXT: }
+
+struct Obj {
+  int a; Obj(); Obj(const Obj& r) = delete; Obj &operator=(const Obj& r);
+  ~Obj();
+};
+ 
+void foo() {
+  int i,count = 0;
+  Obj obj;
+
+  #pragma omp parallel private(i) num_threads(1)
+  {
+      #pragma omp for reduction(+:count) lastprivate(obj)
+      for (i=0; i<1000; i++) {
+            if(i==100) {
+                obj.a = 100;
+                #pragma omp cancel for
+            }
+            count++;
+        }
+    }
+}