1 files changed, 5 insertions, 2 deletions
diff --git a/include/llvm/ADT/IndexedMap.h b/include/llvm/ADT/IndexedMap.h
index 2ffb505..5ba85c0 100644
--- a/include/llvm/ADT/IndexedMap.h
+++ b/include/llvm/ADT/IndexedMap.h
@@ -21,16 +21,19 @@
 #define LLVM_ADT_INDEXEDMAP_H
 
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallVector.h"
 #include <cassert>
 #include <functional>
-#include <vector>
 
 namespace llvm {
 
 template <typename T, typename ToIndexT = llvm::identity<unsigned> >
   class IndexedMap {
     typedef typename ToIndexT::argument_type IndexT;
-    typedef std::vector<T> StorageT;
+    // Prefer SmallVector with zero inline storage over std::vector. IndexedMaps
+    // can grow very large and SmallVector grows more efficiently as long as T
+    // is trivially copyable.
+    typedef SmallVector<T, 0> StorageT;
     StorageT storage_;
     T nullVal_;
     ToIndexT toIndex_;