[Hexagon] Enable auto-vectorization only when -fvectorize was given

llvm-svn: 329923
diff --git a/clang/lib/Driver/ToolChains/Hexagon.cpp b/clang/lib/Driver/ToolChains/Hexagon.cpp
index 25a911f..6402a82 100644
--- a/clang/lib/Driver/ToolChains/Hexagon.cpp
+++ b/clang/lib/Driver/ToolChains/Hexagon.cpp
@@ -520,6 +520,13 @@
     CC1Args.push_back("-target-feature");
     CC1Args.push_back("+reserved-r19");
   }
+  if (Arg *A = DriverArgs.getLastArg(options::OPT_fvectorize,
+                                     options::OPT_fno_vectorize)) {
+    if (A->getOption().matches(options::OPT_fvectorize)) {
+      CC1Args.push_back("-mllvm");
+      CC1Args.push_back("-hexagon-autohvx");
+    }
+  }
 }
 
 void HexagonToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,