[CodeGen][ObjC] Emit the retainRV marker as a module flag instead of

named metadata.

This fixes a bug where ARC contract wasn't inserting the retainRV
marker when LTO was enabled, which caused objects returned from a
function to be auto-released.

rdar://problem/49464214

Differential Revision: https://reviews.llvm.org/D60302

llvm-svn: 358048

2 files changed, 6 insertions, 9 deletions

diff --git a/clang/lib/CodeGen/CGObjC.cpp b/clang/lib/CodeGen/CGObjC.cpp
index 69ced587957..d5906cf994c 100644
--- a/clang/lib/CodeGen/CGObjC.cpp
+++ b/clang/lib/CodeGen/CGObjC.cpp
@@ -2161,14 +2161,10 @@ static void emitAutoreleasedReturnValueMarker(CodeGenFunction &CGF) {
     // with this marker yet, so leave a breadcrumb for the ARC
     // optimizer to pick up.
     } else {
-      llvm::NamedMDNode *metadata =
-        CGF.CGM.getModule().getOrInsertNamedMetadata(
-                            "clang.arc.retainAutoreleasedReturnValueMarker");
-      assert(metadata->getNumOperands() <= 1);
-      if (metadata->getNumOperands() == 0) {
-        auto &ctx = CGF.getLLVMContext();
-        metadata->addOperand(llvm::MDNode::get(ctx,
-                                     llvm::MDString::get(ctx, assembly)));
+      const char *markerKey = "clang.arc.retainAutoreleasedReturnValueMarker";
+      if (!CGF.CGM.getModule().getModuleFlag(markerKey)) {
+        auto *str = llvm::MDString::get(CGF.getLLVMContext(), assembly);
+        CGF.CGM.getModule().addModuleFlag(llvm::Module::Error, markerKey, str);
       }
     }
   }
diff --git a/clang/test/CodeGenObjC/arc-unsafeclaim.m b/clang/test/CodeGenObjC/arc-unsafeclaim.m
index f5982ddc04d..a8011e02418 100644
--- a/clang/test/CodeGenObjC/arc-unsafeclaim.m
+++ b/clang/test/CodeGenObjC/arc-unsafeclaim.m
@@ -231,4 +231,5 @@ void test_cast_to_void() {
 
 // This is always at the end of the module.
 
-// CHECK-OPTIMIZED: !clang.arc.retainAutoreleasedReturnValueMarker = !{!0}
+// CHECK-OPTIMIZED: !llvm.module.flags = !{!0,
+// CHECK-OPTIMIZED: !0 = !{i32 1, !"clang.arc.retainAutoreleasedReturnValueMarker", !"mov{{.*}}marker for objc_retainAutoreleaseReturnValue"}