[CodeGen][ObjC] Annotate calls to objc_retainAutoreleasedReturnValue

with notail on x86-64.

On x86-64, the epilogue code inserted before the tail jump blocks the
autoreleased return optimization.

rdar://problem/38675807

Differential Revision: https://reviews.llvm.org/D59656

llvm-svn: 356705

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 63e991c9370..f48f19966e5 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -2268,6 +2268,12 @@ public:
     return static_cast<const X86_64ABIInfo&>(TargetCodeGenInfo::getABIInfo());
   }
 
+  /// Disable tail call on x86-64. The epilogue code before the tail jump blocks
+  /// the autoreleaseRV/retainRV optimization.
+  bool shouldSuppressTailCallsOfRetainAutoreleasedReturnValue() const override {
+    return true;
+  }
+
   int getDwarfEHStackPointer(CodeGen::CodeGenModule &CGM) const override {
     return 7;
   }