Use v.data() instead of &v[0] when SmallVector v might be empty.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72210 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/DebugInfo.cpp b/lib/Analysis/DebugInfo.cpp
index 9f6cbc9..6bdb64c 100644
--- a/lib/Analysis/DebugInfo.cpp
+++ b/lib/Analysis/DebugInfo.cpp
@@ -442,7 +442,7 @@
   
   Constant *Init = ConstantArray::get(ArrayType::get(EmptyStructPtr,
                                                      Elts.size()),
-                                      &Elts[0], Elts.size());
+                                      Elts.data(), Elts.size());
   // If we already have this array, just return the uniqued version.
   DIDescriptor &Entry = SimpleConstantCache[Init];
   if (!Entry.isNull()) return DIArray(Entry.getGV());