Add a cc1 option to force disabling lifetime-markers emission from clang

Summary: This intended as a debugging/development flag only.

Differential Revision: https://reviews.llvm.org/D28385

llvm-svn: 291300
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 8dd1623..aa08a45 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -312,7 +312,8 @@
   // At O0 and O1 we only run the always inliner which is more efficient. At
   // higher optimization levels we run the normal inliner.
   if (CodeGenOpts.OptimizationLevel <= 1) {
-    bool InsertLifetimeIntrinsics = CodeGenOpts.OptimizationLevel != 0;
+    bool InsertLifetimeIntrinsics = (CodeGenOpts.OptimizationLevel != 0 &&
+                                     !CodeGenOpts.DisableLifetimeMarkers);
     PMBuilder.Inliner = createAlwaysInlinerLegacyPass(InsertLifetimeIntrinsics);
   } else {
     PMBuilder.Inliner = createFunctionInliningPass(