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[DAG] Cleanup "and/or of cmp with single bit diff" fold to use ISD::matchBinaryPredicate 

Prep work as I'm investigating some cases where TLI::convertSetCCLogicToBitwiseLogic should accept vectors.
This commit is contained in:
Simon Pilgrim 2022-05-26 12:34:02 +01:00
parent 8894c05b0d
commit 7b617eef80
1 changed files with 15 additions and 17 deletions
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32
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -5418,29 +5418,27 @@ SDValue DAGCombiner::foldLogicOfSetCCs(bool IsAnd, SDValue N0, SDValue N1,
}
// Turn compare of constants whose difference is 1 bit into add+and+setcc.
// TODO - support non-uniform vector amounts.
if ((IsAnd && CC1 == ISD::SETNE) || (!IsAnd && CC1 == ISD::SETEQ)) {
// Match a shared variable operand and 2 non-opaque constant operands.
ConstantSDNode *C0 = isConstOrConstSplat(LR);
ConstantSDNode *C1 = isConstOrConstSplat(RR);
if (LL == RL && C0 && C1 && !C0->isOpaque() && !C1->isOpaque()) {
auto MatchDiffPow2 = [&](ConstantSDNode *C0, ConstantSDNode *C1) {
// The difference of the constants must be a single bit.
const APInt &CMax =
APIntOps::umax(C0->getAPIntValue(), C1->getAPIntValue());
const APInt &CMin =
APIntOps::umin(C0->getAPIntValue(), C1->getAPIntValue());
// The difference of the constants must be a single bit.
if ((CMax - CMin).isPowerOf2()) {
// and/or (setcc X, CMax, ne), (setcc X, CMin, ne/eq) -->
// setcc ((sub X, CMin), ~(CMax - CMin)), 0, ne/eq
SDValue Max = DAG.getNode(ISD::UMAX, DL, OpVT, LR, RR);
SDValue Min = DAG.getNode(ISD::UMIN, DL, OpVT, LR, RR);
SDValue Offset = DAG.getNode(ISD::SUB, DL, OpVT, LL, Min);
SDValue Diff = DAG.getNode(ISD::SUB, DL, OpVT, Max, Min);
SDValue Mask = DAG.getNOT(DL, Diff, OpVT);
SDValue And = DAG.getNode(ISD::AND, DL, OpVT, Offset, Mask);
SDValue Zero = DAG.getConstant(0, DL, OpVT);
return DAG.getSetCC(DL, VT, And, Zero, CC0);
}
return !C0->isOpaque() && !C1->isOpaque() && (CMax - CMin).isPowerOf2();
};
if (LL == RL && ISD::matchBinaryPredicate(LR, RR, MatchDiffPow2)) {
// and/or (setcc X, CMax, ne), (setcc X, CMin, ne/eq) -->
// setcc ((sub X, CMin), ~(CMax - CMin)), 0, ne/eq
SDValue Max = DAG.getNode(ISD::UMAX, DL, OpVT, LR, RR);
SDValue Min = DAG.getNode(ISD::UMIN, DL, OpVT, LR, RR);
SDValue Offset = DAG.getNode(ISD::SUB, DL, OpVT, LL, Min);
SDValue Diff = DAG.getNode(ISD::SUB, DL, OpVT, Max, Min);
SDValue Mask = DAG.getNOT(DL, Diff, OpVT);
SDValue And = DAG.getNode(ISD::AND, DL, OpVT, Offset, Mask);
SDValue Zero = DAG.getConstant(0, DL, OpVT);
return DAG.getSetCC(DL, VT, And, Zero, CC0);
}
}
}