From 4aafb4ff92ee6b5372aaaa51845445f2418a7fd1 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Thu, 12 Jan 2006 20:22:43 +0000
Subject: [PATCH] Add a simple missing fold to produce this:

        subfic r3, r2, 33

instead of this:

        subfic r2, r2, 32
        addi r3, r2, 1


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25255 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index cb80e250380..9203c81f557 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -696,6 +696,14 @@ SDOperand DAGCombiner::visitADD(SDNode *N) {
       return DAG.getNode(ISD::ADD, VT, N0.getOperand(0),
                          DAG.getConstant(N1C->getValue()+N01C->getValue(), VT));
   }
+  
+  // fold ((c1-A)+c2) -> (c1+c2)-A
+  if (N1C && N0.getOpcode() == ISD::SUB)
+    if (ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.getOperand(0)))
+      return DAG.getNode(ISD::SUB, VT,
+                         DAG.getConstant(N1C->getValue()+N0C->getValue(), VT),
+                         N0.getOperand(1));
+  
   // fold ((0-A) + B) -> B-A
   if (N0.getOpcode() == ISD::SUB && isa<ConstantSDNode>(N0.getOperand(0)) &&
       cast<ConstantSDNode>(N0.getOperand(0))->isNullValue())