From 7042f15bded917ba68e5e66be873ad4d06f9ca2d Mon Sep 17 00:00:00 2001 From: Nate Begeman Date: Tue, 23 Aug 2005 05:41:12 +0000 Subject: [PATCH] Teach the SelectionDAG how to transform select_cc eq, X, 0, 1, 0 into either seteq X, 0 or srl (ctlz X), size(X-1), depending on what's legal for the target. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22978 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index 3bae15c6aab..3ebaaa465f6 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -853,6 +853,23 @@ SDOperand SelectionDAG::SimplifySelectCC(SDOperand N1, SDOperand N2, } } + // Check to see if this is the equivalent of seteq X, 0. + // select_cc seteq X, 0, 1, 0 -> setcc X, 0, seteq -> srl (ctlz X), size(X)-1 + if (N2C && N2C->isNullValue() && N4C && N4C->isNullValue() && + N3C && (N3C->getValue() == 1)) { + MVT::ValueType XType = N1.getValueType(); + if (TLI.getOperationAction(ISD::SETCC, TLI.getSetCCResultTy()) == + TargetLowering::Legal) { + return getSetCC(TLI.getSetCCResultTy(), N1, N2, ISD::SETEQ); + } + if (TLI.getOperationAction(ISD::CTLZ, XType) == TargetLowering::Legal) { + SDOperand Ctlz = getNode(ISD::CTLZ, XType, N1); + return getNode(ISD::SRL, XType, Ctlz, + getConstant(MVT::getSizeInBits(XType)-1, + TLI.getShiftAmountTy())); + } + } + // Check to see if this is an integer abs. select_cc setl[te] X, 0, -X, X -> // Y = sra (X, size(X)-1); xor (add (X, Y), Y) if (N2C && N2C->isNullValue() && (CC == ISD::SETLT || CC == ISD::SETLE) && -- 2.34.1