From ca7c690d3b51f44ccb1ec1bb1c01bd74610b3f8e Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Tue, 15 Dec 2009 00:41:36 +0000
Subject: Propagate zest through logical shift.

llvm-svn: 91378
---
 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 10 ++++++++++
 1 file changed, 10 insertions(+)

(limited to 'llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp')

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 027348c0f6d..52b7ed5f158 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -3278,6 +3278,16 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
     if (SCC.getNode()) return SCC;
   }
 
+  // (zext (shl (zext x), y)) -> (shl (zext x), (zext y))
+  if ((N0.getOpcode() == ISD::SHL || N0.getOpcode() == ISD::SRL) &&
+      N0.getOperand(0).getOpcode() == ISD::ZERO_EXTEND &&
+      N0.hasOneUse()) {
+    DebugLoc dl = N->getDebugLoc();
+    return DAG.getNode(N0.getOpcode(), dl, VT,
+                       DAG.getNode(ISD::ZERO_EXTEND, dl, VT, N0.getOperand(0)),
+                       DAG.getNode(ISD::ZERO_EXTEND, dl, VT, N0.getOperand(1)));
+  }
+
   return SDValue();
 }
 
-- 
cgit v1.2.3