diff options
Diffstat (limited to 'llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 33 |
1 files changed, 16 insertions, 17 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 73f661d7c04..76442fbda93 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -7088,26 +7088,25 @@ SDValue DAGCombiner::visitFREM(SDNode *N) { SDValue DAGCombiner::visitFSQRT(SDNode *N) { if (DAG.getTarget().Options.UnsafeFPMath) { - // Compute this as 1/(1/sqrt(X)): the reciprocal of the reciprocal sqrt. + // Compute this as X * (1/sqrt(X)) = X * (X ** -0.5) if (SDValue RV = BuildRsqrtEstimate(N->getOperand(0))) { AddToWorklist(RV.getNode()); - RV = BuildReciprocalEstimate(RV); - if (RV.getNode()) { - // Unfortunately, RV is now NaN if the input was exactly 0. - // Select out this case and force the answer to 0. - EVT VT = RV.getValueType(); - - SDValue Zero = DAG.getConstantFP(0.0, VT); - SDValue ZeroCmp = - DAG.getSetCC(SDLoc(N), TLI.getSetCCResultType(*DAG.getContext(), VT), - N->getOperand(0), Zero, ISD::SETEQ); - AddToWorklist(ZeroCmp.getNode()); - AddToWorklist(RV.getNode()); + EVT VT = RV.getValueType(); + RV = DAG.getNode(ISD::FMUL, SDLoc(N), VT, N->getOperand(0), RV); + AddToWorklist(RV.getNode()); - RV = DAG.getNode(VT.isVector() ? ISD::VSELECT : ISD::SELECT, - SDLoc(N), VT, ZeroCmp, Zero, RV); - return RV; - } + // Unfortunately, RV is now NaN if the input was exactly 0. + // Select out this case and force the answer to 0. + SDValue Zero = DAG.getConstantFP(0.0, VT); + SDValue ZeroCmp = + DAG.getSetCC(SDLoc(N), TLI.getSetCCResultType(*DAG.getContext(), VT), + N->getOperand(0), Zero, ISD::SETEQ); + AddToWorklist(ZeroCmp.getNode()); + AddToWorklist(RV.getNode()); + + RV = DAG.getNode(VT.isVector() ? ISD::VSELECT : ISD::SELECT, + SDLoc(N), VT, ZeroCmp, Zero, RV); + return RV; } } return SDValue(); |
