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[DAG] visitADDSAT/visitSUBSAT - merge scalar/vector canonicalization and constant folding. 

Match order of most of the other integer opcode combines
This commit is contained in:
Simon Pilgrim 2021-12-19 13:19:40 +00:00
parent 67cce1ceee
commit efec3a26b4
1 changed files with 22 additions and 23 deletions
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45
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -2549,6 +2549,19 @@ SDValue DAGCombiner::visitADDSAT(SDNode *N) {
EVT VT = N0.getValueType();
SDLoc DL(N);
// fold (add_sat x, undef) -> -1
if (N0.isUndef() || N1.isUndef())
return DAG.getAllOnesConstant(DL, VT);
// fold (add_sat c1, c2) -> c3
if (SDValue C = DAG.FoldConstantArithmetic(Opcode, DL, VT, {N0, N1}))
return C;
// canonicalize constant to RHS
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
!DAG.isConstantIntBuildVectorOrConstantInt(N1))
return DAG.getNode(Opcode, DL, VT, N1, N0);
// fold vector ops
if (VT.isVector()) {
// TODO SimplifyVBinOp
@ -2556,20 +2569,6 @@ SDValue DAGCombiner::visitADDSAT(SDNode *N) {
// fold (add_sat x, 0) -> x, vector edition
if (ISD::isConstantSplatVectorAllZeros(N1.getNode()))
return N0;
if (ISD::isConstantSplatVectorAllZeros(N0.getNode()))
return N1;
}
// fold (add_sat x, undef) -> -1
if (N0.isUndef() || N1.isUndef())
return DAG.getAllOnesConstant(DL, VT);
if (DAG.isConstantIntBuildVectorOrConstantInt(N0)) {
// canonicalize constant to RHS
if (!DAG.isConstantIntBuildVectorOrConstantInt(N1))
return DAG.getNode(Opcode, DL, VT, N1, N0);
// fold (add_sat c1, c2) -> c3
return DAG.FoldConstantArithmetic(Opcode, DL, VT, {N0, N1});
}
// fold (add_sat x, 0) -> x
@ -3606,15 +3605,6 @@ SDValue DAGCombiner::visitSUBSAT(SDNode *N) {
EVT VT = N0.getValueType();
SDLoc DL(N);
// fold vector ops
if (VT.isVector()) {
// TODO SimplifyVBinOp
// fold (sub_sat x, 0) -> x, vector edition
if (ISD::isConstantSplatVectorAllZeros(N1.getNode()))
return N0;
}
// fold (sub_sat x, undef) -> 0
if (N0.isUndef() || N1.isUndef())
return DAG.getConstant(0, DL, VT);
@ -3627,6 +3617,15 @@ SDValue DAGCombiner::visitSUBSAT(SDNode *N) {
if (SDValue C = DAG.FoldConstantArithmetic(N->getOpcode(), DL, VT, {N0, N1}))
return C;
// fold vector ops
if (VT.isVector()) {
// TODO SimplifyVBinOp
// fold (sub_sat x, 0) -> x, vector edition
if (ISD::isConstantSplatVectorAllZeros(N1.getNode()))
return N0;
}
// fold (sub_sat x, 0) -> x
if (isNullConstant(N1))
return N0;