2 files changed, 42 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 2fc16049f6b..54468d939d3 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -2912,12 +2912,30 @@ void CodeGenFunction::EmitDelegateCallArg(CallArgList &args,
   assert(!isInAllocaArgument(CGM.getCXXABI(), type) &&
          "cannot emit delegate call arguments for inalloca arguments!");
 
+  // GetAddrOfLocalVar returns a pointer-to-pointer for references,
+  // but the argument needs to be the original pointer.
+  if (type->isReferenceType()) {
+    args.add(RValue::get(Builder.CreateLoad(local)), type);
+
+  // In ARC, move out of consumed arguments so that the release cleanup
+  // entered by StartFunction doesn't cause an over-release.  This isn't
+  // optimal -O0 code generation, but it should get cleaned up when
+  // optimization is enabled.  This also assumes that delegate calls are
+  // performed exactly once for a set of arguments, but that should be safe.
+  } else if (getLangOpts().ObjCAutoRefCount &&
+             param->hasAttr<NSConsumedAttr>() &&
+             type->isObjCRetainableType()) {
+    llvm::Value *ptr = Builder.CreateLoad(local);
+    auto null =
+      llvm::ConstantPointerNull::get(cast<llvm::PointerType>(ptr->getType()));
+    Builder.CreateStore(null, local);
+    args.add(RValue::get(ptr), type);
+
   // For the most part, we just need to load the alloca, except that
   // aggregate r-values are actually pointers to temporaries.
-  if (type->isReferenceType())
-    args.add(RValue::get(Builder.CreateLoad(local)), type);
-  else
+  } else {
     args.add(convertTempToRValue(local, type, loc), type);
+  }
 }
 
 static bool isProvablyNull(llvm::Value *addr) {
diff --git a/clang/test/CodeGenObjCXX/arc-attrs.mm b/clang/test/CodeGenObjCXX/arc-attrs.mm
index 0f0610f1721..0b64d775660 100644
--- a/clang/test/CodeGenObjCXX/arc-attrs.mm
+++ b/clang/test/CodeGenObjCXX/arc-attrs.mm
@@ -46,3 +46,24 @@ void templateTest() {
   // CHECK-NEXT: call void @objc_storeStrong(i8** [[X]], i8* null)
   // CHECK-NEXT: ret void
 }
+
+// PR27887
+struct ForwardConsumed {
+  ForwardConsumed(__attribute__((ns_consumed)) id x);
+};
+
+ForwardConsumed::ForwardConsumed(__attribute__((ns_consumed)) id x) {}
+
+// CHECK: define void @_ZN15ForwardConsumedC2EP11objc_object(
+// CHECK-NOT:  objc_retain
+// CHECK:      store i8* {{.*}}, i8** [[X:%.*]],
+// CHECK-NOT:  [[X]]
+// CHECK:      call void @objc_storeStrong(i8** [[X]], i8* null)
+
+// CHECK: define void @_ZN15ForwardConsumedC1EP11objc_object(
+// CHECK-NOT:  objc_retain
+// CHECK:      store i8* {{.*}}, i8** [[X:%.*]],
+// CHECK:      [[T0:%.*]] = load i8*, i8** [[X]],
+// CHECK-NEXT: store i8* null, i8** [[X]],
+// CHECK-NEXT: call void @_ZN15ForwardConsumedC2EP11objc_object({{.*}}, i8* [[T0]])
+// CHECK:      call void @objc_storeStrong(i8** [[X]], i8* null)