Switch SelectionDAG::ReplaceAllUsesOfValueWith to use a SmallSetVector for
the users set (most nodes have 1 or 2 users).  This speeds up the isel pass
3.2% on kimwitu.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33849 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 24b49b2..cced06b 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2409,8 +2409,9 @@
     return;
   }
   
-  // Get all of the users in a nice, deterministically ordered, uniqued set.
-  SetVector<SDNode*> Users(From.Val->use_begin(), From.Val->use_end());
+  // Get all of the users of From.Val.  We want these in a nice,
+  // deterministically ordered and uniqued set, so we use a SmallSetVector.
+  SmallSetVector<SDNode*, 16> Users(From.Val->use_begin(), From.Val->use_end());
 
   while (!Users.empty()) {
     // We know that this user uses some value of From.  If it is the right