fold (shl x, 1) -> (add x, x)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25120 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 3 insertions, 20 deletions

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 30a4c9f637..9770ae232b 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1282,6 +1282,9 @@ SDOperand DAGCombiner::visitSHL(SDNode *N) {
   // fold (shl x, 0) -> x
   if (N1C && N1C->isNullValue())
     return N0;
+  // fold (shl x, 1) -> (add x, x)
+  if (N1C && N1C->getValue() == 1)
+    return DAG.getNode(ISD::ADD, VT, N0, N0);
   // if (shl x, c) is known to be zero, return 0
   if (N1C && MaskedValueIsZero(SDOperand(N, 0), ~0ULL >> (64-OpSizeInBits),TLI))
     return DAG.getConstant(0, VT);
diff --git a/lib/Target/X86/X86ISelDAGToDAG.cpp b/lib/Target/X86/X86ISelDAGToDAG.cpp
index 1a926d076e..437519c3f1 100644
--- a/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ b/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -363,26 +363,6 @@ SDOperand X86DAGToDAGISel::Select(SDOperand N) {
   switch (Node->getOpcode()) {
     default: break;
 
-    case ISD::SHL:
-      if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Node->getOperand(1))) {
-        if (CN->getValue() == 1) {
-          // X = SHL Y, 1  -> X = ADD Y, Y
-          switch (NVT) {
-            default: assert(0 && "Cannot shift this type!");
-            case MVT::i8:  Opc = X86::ADD8rr; break;
-            case MVT::i16: Opc = X86::ADD16rr; break;
-            case MVT::i32: Opc = X86::ADD32rr; break;
-          }
-          SDOperand Tmp0 = Select(Node->getOperand(0));
-          if (Node->hasOneUse())
-            return CurDAG->SelectNodeTo(Node, Opc, NVT, Tmp0, Tmp0);
-          else
-            return CodeGenMap[N] =
-              CurDAG->getTargetNode(Opc, NVT, Tmp0, Tmp0);
-        }
-      }
-      break;
-
     case ISD::TRUNCATE: {
       unsigned Reg;
       MVT::ValueType VT;