Changes in directory llvm/lib/CodeGen/SelectionDAG:
DAGCombiner.cpp updated: 1.95 -> 1.96 --- Log message: handle combining A / (B << N) into A >>u (log2(B)+N) when B is a power of 2 --- Diffs of the changes: (+13 -2) DAGCombiner.cpp | 15 +++++++++++++-- 1 files changed, 13 insertions(+), 2 deletions(-) Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp diff -u llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.95 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.96 --- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.95 Fri Feb 3 16:24:05 2006 +++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Sun Feb 5 01:20:23 2006 @@ -778,15 +778,26 @@ return DAG.getNode(ISD::UDIV, VT, N0, N1); // fold (udiv x, (1 << c)) -> x >>u c if (N1C && isPowerOf2_64(N1C->getValue())) - return DAG.getNode(ISD::SRL, N->getValueType(0), N0, + return DAG.getNode(ISD::SRL, VT, N0, DAG.getConstant(Log2_64(N1C->getValue()), TLI.getShiftAmountTy())); + // fold (udiv x, (shl c, y)) -> x >>u (log2(c)+y) iff c is power of 2 + if (N1.getOpcode() == ISD::SHL) { + if (ConstantSDNode *SHC = dyn_cast<ConstantSDNode>(N1.getOperand(0))) { + if (isPowerOf2_64(SHC->getValue())) { + MVT::ValueType ADDVT = N1.getOperand(1).getValueType(); + return DAG.getNode(ISD::SRL, VT, N0, + DAG.getNode(ISD::ADD, ADDVT, N1.getOperand(1), + DAG.getConstant(Log2_64(SHC->getValue()), + ADDVT))); + } + } + } // fold (udiv x, c) -> alternate if (N1C && N1C->getValue() && !TLI.isIntDivCheap()) { SDOperand Op = BuildUDIV(N); if (Op.Val) return Op; } - return SDOperand(); } _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits