commit ca7c690d3b51f44ccb1ec1bb1c01bd74610b3f8e
author Evan Cheng <evan.cheng@apple.com> Tue Dec 15 00:41:36 2009 +0000
committer Evan Cheng <evan.cheng@apple.com> Tue Dec 15 00:41:36 2009 +0000
tree 3dc184fc2633201d68b8c85a470656b183119665
parent d5218331f75a6e3456747ec90e0941612c1a7c4c

Propagate zest through logical shift.

llvm-svn: 91378

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 027348c..52b7ed5 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -3278,6 +3278,16 @@
     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();
 }