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[DAGCombiner] rename variables for readability; NFC 

PR46406 shows a pattern where we can do better, so try to clean this up
before adding more code.
This commit is contained in:
Sanjay Patel 2020-06-26 14:20:40 -04:00
parent 67043ed885
commit e7f7715eb9
1 changed files with 11 additions and 12 deletions
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23
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -13215,22 +13215,21 @@ SDValue DAGCombiner::visitFDIV(SDNode *N) {
} else if (N1.getOpcode() == ISD::FMUL) {
// Look through an FMUL. Even though this won't remove the FDIV directly,
// it's still worthwhile to get rid of the FSQRT if possible.
SDValue SqrtOp;
SDValue OtherOp;
SDValue Sqrt, Y;
if (N1.getOperand(0).getOpcode() == ISD::FSQRT) {
SqrtOp = N1.getOperand(0);
OtherOp = N1.getOperand(1);
Sqrt = N1.getOperand(0);
Y = N1.getOperand(1);
} else if (N1.getOperand(1).getOpcode() == ISD::FSQRT) {
SqrtOp = N1.getOperand(1);
OtherOp = N1.getOperand(0);
Sqrt = N1.getOperand(1);
Y = N1.getOperand(0);
}
if (SqrtOp.getNode()) {
if (Sqrt.getNode()) {
// We found a FSQRT, so try to make this fold:
// x / (y * sqrt(z)) -> x * (rsqrt(z) / y)
if (SDValue RV = buildRsqrtEstimate(SqrtOp.getOperand(0), Flags)) {
RV = DAG.getNode(ISD::FDIV, SDLoc(N1), VT, RV, OtherOp, Flags);
AddToWorklist(RV.getNode());
return DAG.getNode(ISD::FMUL, DL, VT, N0, RV, Flags);
// X / (Y * sqrt(Z)) -> X * (rsqrt(Z) / Y)
if (SDValue Rsqrt = buildRsqrtEstimate(Sqrt.getOperand(0), Flags)) {
SDValue Div = DAG.getNode(ISD::FDIV, SDLoc(N1), VT, Rsqrt, Y, Flags);
AddToWorklist(Div.getNode());
return DAG.getNode(ISD::FMUL, DL, VT, N0, Div, Flags);
}
}
}