From 221cd2f0813be675784b9825aee9f74f22026247 Mon Sep 17 00:00:00 2001 From: Dale Johannesen Date: Tue, 2 Dec 2008 01:30:54 +0000 Subject: [PATCH] Add a few more transformations. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60391 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 6b35126a10e..629e22d11ab 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -1013,6 +1013,30 @@ SDValue DAGCombiner::visitADD(SDNode *N) { // fold ((B-A)+A) -> B if (N0.getOpcode() == ISD::SUB && N1 == N0.getOperand(1)) return N0.getOperand(0); + // fold (A+(B-(A+C))) to (B-C) + if (N1.getOpcode() == ISD::SUB && N1.getOperand(1).getOpcode() == ISD::ADD && + N0 == N1.getOperand(1).getOperand(0)) { + return DAG.getNode(ISD::SUB, VT, N1.getOperand(0), + N1.getOperand(1).getOperand(1)); + } + // fold (A+(B-(C+A))) to (B-C) + if (N1.getOpcode() == ISD::SUB && N1.getOperand(1).getOpcode() == ISD::ADD && + N0 == N1.getOperand(1).getOperand(1)) { + return DAG.getNode(ISD::SUB, VT, N1.getOperand(0), + N1.getOperand(1).getOperand(0)); + } + // 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); + SDValue N01 = N0.getOperand(1); + SDValue N10 = N1.getOperand(0); + SDValue N11 = N1.getOperand(1); + if (isa(N00) || isa(N10)) { + return DAG.getNode(ISD::SUB, VT, + DAG.getNode(ISD::ADD, VT, N00, N10), + DAG.getNode(ISD::ADD, VT, N01, N11)); + } + } if (!VT.isVector() && SimplifyDemandedBits(SDValue(N, 0))) return SDValue(N, 0); -- 2.34.1