[ObjC][ARC] Convert the retainRV marker that is passed as a named

metadata into a module flag in the auto-upgrader and make the ARC
contract pass read the marker as a module flag.

This is needed to fix 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/D60303

llvm-svn: 358047

1 files changed, 2 insertions, 9 deletions

diff --git a/llvm/lib/Transforms/ObjCARC/ObjCARCContract.cpp b/llvm/lib/Transforms/ObjCARC/ObjCARCContract.cpp
index 6613f6a76d0..ff07cfe00d4 100644
--- a/llvm/lib/Transforms/ObjCARC/ObjCARCContract.cpp
+++ b/llvm/lib/Transforms/ObjCARC/ObjCARCContract.cpp
@@ -744,15 +744,8 @@ bool ObjCARCContract::doInitialization(Module &M) {
   EP.init(&M);
 
   // Initialize RVInstMarker.
-  RVInstMarker = nullptr;
-  if (NamedMDNode *NMD =
-          M.getNamedMetadata("clang.arc.retainAutoreleasedReturnValueMarker"))
-    if (NMD->getNumOperands() == 1) {
-      const MDNode *N = NMD->getOperand(0);
-      if (N->getNumOperands() == 1)
-        if (const MDString *S = dyn_cast<MDString>(N->getOperand(0)))
-          RVInstMarker = S;
-    }
+  const char *MarkerKey = "clang.arc.retainAutoreleasedReturnValueMarker";
+  RVInstMarker = dyn_cast_or_null<MDString>(M.getModuleFlag(MarkerKey));
 
   return false;
 }