[llvm-commits] [llvm] r60432 - /llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

[Dale Johannesen]

Author: johannes
Date: Tue Dec  2 12:40:40 2008
New Revision: 60432

URL: http://llvm.org/viewvc/llvm-project?rev=60432&view=rev
Log:
One more transformation.


Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=60432&r1=60431&r2=60432&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Tue Dec  2 12:40:40 2008
@@ -1025,6 +1025,14 @@
     return DAG.getNode(ISD::SUB, VT, N1.getOperand(0),
                        N1.getOperand(1).getOperand(0));
   }
+  // fold (A+((B-A)+-C)) to (B+-C)
+  if ((N1.getOpcode() == ISD::SUB || N1.getOpcode() == ISD::ADD) &&
+      N1.getOperand(0).getOpcode() == ISD::SUB &&
+      N0 == N1.getOperand(0).getOperand(1)) {
+    return DAG.getNode(N1.getOpcode(), VT, N1.getOperand(0).getOperand(0),
+                       N1.getOperand(1));
+  }
+
   // fold (A-B)+(C-D) to (A+C)-(B+D) when A or C is constant
   if (N0.getOpcode() == ISD::SUB && N1.getOpcode() == ISD::SUB) {
     SDValue N00 = N0.getOperand(0);