[arcmt] Use CFBridgingRetain/CFBridgingRelease instead of __bridge_retained/__bridge_transfer
when migrating.

rdar://11569198

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@157785 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/ARCMigrate/Transforms.cpp b/lib/ARCMigrate/Transforms.cpp
index 24b6505..7159836 100644
--- a/lib/ARCMigrate/Transforms.cpp
+++ b/lib/ARCMigrate/Transforms.cpp
@@ -10,6 +10,7 @@
 #include "Transforms.h"
 #include "Internals.h"
 #include "clang/Sema/SemaDiagnostic.h"
+#include "clang/Sema/Sema.h"
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/AST/StmtVisitor.h"
 #include "clang/Lex/Lexer.h"
@@ -25,6 +26,13 @@
 
 ASTTraverser::~ASTTraverser() { }
 
+bool MigrationPass::CFBridgingFunctionsDefined() {
+  if (!EnableCFBridgeFns.hasValue())
+    EnableCFBridgeFns = SemaRef.isKnownName("CFBridgingRetain") &&
+                        SemaRef.isKnownName("CFBridgingRelease");
+  return *EnableCFBridgeFns;
+}
+
 //===----------------------------------------------------------------------===//
 // Helpers.
 //===----------------------------------------------------------------------===//