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.

llvm-svn: 33849

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 24b49b246cc..cced06be1f5 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2409,8 +2409,9 @@ void SelectionDAG::ReplaceAllUsesOfValueWith(SDOperand From, SDOperand To,
     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