Commit e6011968 authored by QingShan Zhang's avatar QingShan Zhang
Browse files

[NFC][DAGCombine] Move the fold of a*b-c and a-b*c into lambda function 

This will help the review of https://reviews.llvm.org/D75982. It is
a simple code refactor.
parent 57da8f72

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

+24 −11
Original line number Diff line number Diff line
@@ -11916,20 +11916,33 @@ SDValue DAGCombiner::visitFSUBForFMACombine(SDNode *N) { 
  };















  // fold (fsub (fmul x, y), z) -> (fma x, y, (fneg z))













  if (isContractableFMUL(N0) && (Aggressive || N0->hasOneUse())) {













    return DAG.getNode(PreferredFusedOpcode, SL, VT,













                       N0.getOperand(0), N0.getOperand(1),













                       DAG.getNode(ISD::FNEG, SL, VT, N1), Flags);













  auto tryToFoldXYSubZ = [&](SDValue XY, SDValue Z) {













    if (isContractableFMUL(XY) && (Aggressive || XY->hasOneUse())) {













      return DAG.getNode(PreferredFusedOpcode, SL, VT, XY.getOperand(0),













                         XY.getOperand(1), DAG.getNode(ISD::FNEG, SL, VT, Z),













                         Flags);















    }













    return SDValue();













  };





























  // fold (fsub x, (fmul y, z)) -> (fma (fneg y), z, x)















  // Note: Commutes FSUB operands.













  if (isContractableFMUL(N1) && (Aggressive || N1->hasOneUse())) {













  auto tryToFoldXSubYZ = [&](SDValue X, SDValue YZ) {













    if (isContractableFMUL(YZ) && (Aggressive || YZ->hasOneUse())) {















      return DAG.getNode(PreferredFusedOpcode, SL, VT,













                       DAG.getNode(ISD::FNEG, SL, VT,













                                   N1.getOperand(0)),













                       N1.getOperand(1), N0, Flags);













                         DAG.getNode(ISD::FNEG, SL, VT, YZ.getOperand(0)),













                         YZ.getOperand(1), X, Flags);















    }













    return SDValue();













  };

























  // fold (fsub (fmul x, y), z) -> (fma x, y, (fneg z))













  if (SDValue V = tryToFoldXYSubZ(N0, N1))













    return V;

























  // fold (fsub x, (fmul y, z)) -> (fma (fneg y), z, x)













  if (SDValue V = tryToFoldXSubYZ(N0, N1))













    return V;





























  // fold (fsub (fneg (fmul, x, y)), z) -> (fma (fneg x), y, (fneg z))















  if (N0.getOpcode() == ISD::FNEG && isContractableFMUL(N0.getOperand(0)) &&