IRGen: Start using the WriteThinLTOBitcode pass.

This is the final change necessary to support CFI with ThinLTO.

Differential Revision: https://reviews.llvm.org/D28843

llvm-svn: 292662
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index bac1e89..4fdffde 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -689,9 +689,11 @@
     break;
 
   case Backend_EmitBC:
-    PerModulePasses.add(createBitcodeWriterPass(
-        *OS, CodeGenOpts.EmitLLVMUseLists, CodeGenOpts.EmitSummaryIndex,
-        CodeGenOpts.EmitSummaryIndex));
+    if (CodeGenOpts.EmitSummaryIndex)
+      PerModulePasses.add(createWriteThinLTOBitcodePass(*OS));
+    else
+      PerModulePasses.add(
+          createBitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists));
     break;
 
   case Backend_EmitLL: