From: John McCall <rjmccall@apple.com>
Date: Thu, 14 Dec 2017 18:21:14 +0000 (+0000)
Subject: In an ARC lambda-to-block conversion thunk, reclaim the return value of
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=a66f080af76f4d928571c4a61ce5ce88c0f41b49;p=clang

In an ARC lambda-to-block conversion thunk, reclaim the return value of
the lambda so that we don't over-release it.

Patch by Dan Zimmerman!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@320721 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/CGClass.cpp b/lib/CodeGen/CGClass.cpp
index 9bbdc98f1f..a6915071ec 100644
--- a/lib/CodeGen/CGClass.cpp
+++ b/lib/CodeGen/CGClass.cpp
@@ -2777,9 +2777,12 @@ void CodeGenFunction::EmitForwardingCallToLambda(
   RValue RV = EmitCall(calleeFnInfo, callee, returnSlot, callArgs);
 
   // If necessary, copy the returned value into the slot.
-  if (!resultType->isVoidType() && returnSlot.isNull())
+  if (!resultType->isVoidType() && returnSlot.isNull()) {
+    if (getLangOpts().ObjCAutoRefCount && resultType->isObjCRetainableType()) {
+      RV = RValue::get(EmitARCRetainAutoreleasedReturnValue(RV.getScalarVal()));
+    }
     EmitReturnOfRValue(RV, resultType);
-  else
+  } else
     EmitBranchThroughCleanup(ReturnBlock);
 }
 
diff --git a/test/CodeGenObjCXX/arc-forwarded-lambda-call.mm b/test/CodeGenObjCXX/arc-forwarded-lambda-call.mm
new file mode 100644
index 0000000000..35abe19183
--- /dev/null
+++ b/test/CodeGenObjCXX/arc-forwarded-lambda-call.mm
@@ -0,0 +1,23 @@
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.12.0 -emit-llvm -disable-llvm-passes -O3 -fblocks -fobjc-arc -fobjc-runtime-has-weak -std=c++11 -o - %s | FileCheck %s
+
+void test0(id x) {
+  extern void test0_helper(id (^)(void));
+  test0_helper([=]() { return x; });
+  // CHECK-LABEL: define internal i8* @___Z5test0P11objc_object_block_invoke
+  // CHECK: [[T0:%.*]] = call i8* @"_ZZ5test0P11objc_objectENK3$_0clEv"
+  // CHECK-NEXT: [[T1:%.*]] = call i8* @objc_retainAutoreleasedReturnValue(i8* [[T0]])
+  // CHECK-NEXT: [[T2:%.*]] = tail call i8* @objc_autoreleaseReturnValue(i8* [[T1]])
+  // CHECK-NEXT: ret i8* [[T2]]
+}
+
+id test1_rv;
+
+void test1() {
+  extern void test1_helper(id (*)(void));
+  test1_helper([](){ return test1_rv; });
+  // CHECK-LABEL: define internal i8* @"_ZZ5test1vEN3$_18__invokeEv"
+  // CHECK: [[T0:%.*]] = call i8* @"_ZZ5test1vENK3$_1clEv"
+  // CHECK-NEXT: [[T1:%.*]] = call i8* @objc_retainAutoreleasedReturnValue(i8* [[T0]])
+  // CHECK-NEXT: [[T2:%.*]] = tail call i8* @objc_autoreleaseReturnValue(i8* [[T1]])
+  // CHECK-NEXT: ret i8* [[T2]]
+}