Use SmallVectorImpl instead of SmallVector for iterators and references to avoid specifying the vector size unnecessarily.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185512 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveVariables.cpp b/lib/CodeGen/LiveVariables.cpp
index 4e83fc8..6f75700 100644
--- a/lib/CodeGen/LiveVariables.cpp
+++ b/lib/CodeGen/LiveVariables.cpp
@@ -609,9 +609,9 @@
     // if they have PHI nodes, and if so, we simulate an assignment at the end
     // of the current block.
     if (!PHIVarInfo[MBB->getNumber()].empty()) {
-      SmallVector<unsigned, 4>& VarInfoVec = PHIVarInfo[MBB->getNumber()];
+      SmallVectorImpl<unsigned> &VarInfoVec = PHIVarInfo[MBB->getNumber()];
 
-      for (SmallVector<unsigned, 4>::iterator I = VarInfoVec.begin(),
+      for (SmallVectorImpl<unsigned>::iterator I = VarInfoVec.begin(),
              E = VarInfoVec.end(); I != E; ++I)
         // Mark it alive only in the block we are representing.
         MarkVirtRegAliveInBlock(getVarInfo(*I),MRI->getVRegDef(*I)->getParent(),