From 3e9f3a0389488701bd1cb5c778d0e785c827d790 Mon Sep 17 00:00:00 2001
From: Michael Gottesman <mgottesman@apple.com>
Date: Fri, 29 Mar 2013 21:15:23 +0000
Subject: [PATCH] Add clang.arc.used to ModuleHasARC so ARC always runs if said
 call is present in a module.

clang.arc.used is an interesting call for ARC since ObjCARCContract
needs to run to remove said intrinsic to avoid a linker error (since the
call does not exist).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178369 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/ObjCARC/ObjCARC.h                 |  3 ++-
 ...ang-arc-used-intrinsic-removed-if-isolated.ll | 16 ++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)
 create mode 100644 test/Transforms/ObjCARC/clang-arc-used-intrinsic-removed-if-isolated.ll

diff --git a/lib/Transforms/ObjCARC/ObjCARC.h b/lib/Transforms/ObjCARC/ObjCARC.h
index 614fa29e3e6..39670f339e9 100644
--- a/lib/Transforms/ObjCARC/ObjCARC.h
+++ b/lib/Transforms/ObjCARC/ObjCARC.h
@@ -64,7 +64,8 @@ static inline bool ModuleHasARC(const Module &M) {
     M.getNamedValue("objc_copyWeak") ||
     M.getNamedValue("objc_retainedObject") ||
     M.getNamedValue("objc_unretainedObject") ||
-    M.getNamedValue("objc_unretainedPointer");
+    M.getNamedValue("objc_unretainedPointer") ||
+    M.getNamedValue("clang.arc.use");
 }
 
 /// \enum InstructionClass
diff --git a/test/Transforms/ObjCARC/clang-arc-used-intrinsic-removed-if-isolated.ll b/test/Transforms/ObjCARC/clang-arc-used-intrinsic-removed-if-isolated.ll
new file mode 100644
index 00000000000..4215b5c3646
--- /dev/null
+++ b/test/Transforms/ObjCARC/clang-arc-used-intrinsic-removed-if-isolated.ll
@@ -0,0 +1,16 @@
+; RUN: opt -objc-arc-contract -S < %s | FileCheck %s
+
+; This file makes sure that clang.arc.used is removed even if no other ARC
+; interesting calls are in the module.
+
+declare void @clang.arc.use(...) nounwind
+
+; Kill calls to @clang.arc.use(...)
+; CHECK: define void @test0(
+; CHECK-NOT: clang.arc.use
+; CHECK: }
+define void @test0(i8* %a, i8* %b) {
+  call void (...)* @clang.arc.use(i8* %a, i8* %b) nounwind
+  ret void
+}
+