diff options
Diffstat (limited to 'llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 1e902bac94d..d8c14da15dc 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -337,6 +337,7 @@ namespace { SDValue visitShiftByConstant(SDNode *N, ConstantSDNode *Amt); SDValue foldSelectOfConstants(SDNode *N); + SDValue foldBinOpIntoSelect(SDNode *BO); bool SimplifySelectOps(SDNode *SELECT, SDValue LHS, SDValue RHS); SDValue SimplifyBinOpWithSameOpcodeHands(SDNode *N); SDValue SimplifySelect(const SDLoc &DL, SDValue N0, SDValue N1, SDValue N2); @@ -1747,6 +1748,59 @@ static ConstantSDNode *getAsNonOpaqueConstant(SDValue N) { return Const != nullptr && !Const->isOpaque() ? Const : nullptr; } +SDValue DAGCombiner::foldBinOpIntoSelect(SDNode *BO) { + auto BinOpcode = BO->getOpcode(); + assert((BinOpcode == ISD::ADD || BinOpcode == ISD::SUB || + BinOpcode == ISD::MUL || BinOpcode == ISD::SDIV || + BinOpcode == ISD::UDIV || BinOpcode == ISD::SREM || + BinOpcode == ISD::UREM || BinOpcode == ISD::AND || + BinOpcode == ISD::OR || BinOpcode == ISD::XOR || + BinOpcode == ISD::SHL || BinOpcode == ISD::SRL || + BinOpcode == ISD::SRA || BinOpcode == ISD::FADD || + BinOpcode == ISD::FSUB || BinOpcode == ISD::FMUL || + BinOpcode == ISD::FDIV || BinOpcode == ISD::FREM) && + "Unexpected binary operator"); + + SDValue C1 = BO->getOperand(1); + if (!isConstantOrConstantVector(C1) && + !isConstantFPBuildVectorOrConstantFP(C1)) + return SDValue(); + + // Don't do this unless the old select is going away. We want to eliminate the + // binary operator, not replace a binop with a select. + // TODO: Handle ISD::SELECT_CC. + SDValue Sel = BO->getOperand(0); + if (Sel.getOpcode() != ISD::SELECT || !Sel.hasOneUse()) + return SDValue(); + + SDValue CT = Sel.getOperand(1); + if (!isConstantOrConstantVector(CT) && + !isConstantFPBuildVectorOrConstantFP(CT)) + return SDValue(); + + SDValue CF = Sel.getOperand(2); + if (!isConstantOrConstantVector(CF) && + !isConstantFPBuildVectorOrConstantFP(CF)) + return SDValue(); + + // We have a select-of-constants followed by a binary operator with a + // constant. Eliminate the binop by pulling the constant math into the select. + // Example: add (select Cond, CT, CF), C1 --> select Cond, CT + C1, CF + C1 + EVT VT = Sel.getValueType(); + SDLoc DL(Sel); + SDValue NewCT = DAG.getNode(BinOpcode, DL, VT, CT, C1); + assert((isConstantOrConstantVector(NewCT) || + isConstantFPBuildVectorOrConstantFP(NewCT)) && + "Failed to constant fold a binop with constant operands"); + + SDValue NewCF = DAG.getNode(BinOpcode, DL, VT, CF, C1); + assert((isConstantOrConstantVector(NewCF) || + isConstantFPBuildVectorOrConstantFP(NewCF)) && + "Failed to constant fold a binop with constant operands"); + + return DAG.getSelect(DL, VT, Sel.getOperand(0), NewCT, NewCF); +} + SDValue DAGCombiner::visitADD(SDNode *N) { SDValue N0 = N->getOperand(0); SDValue N1 = N->getOperand(1); @@ -1795,6 +1849,9 @@ SDValue DAGCombiner::visitADD(SDNode *N) { } } + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + // reassociate add if (SDValue RADD = ReassociateOps(ISD::ADD, DL, N0, N1)) return RADD; @@ -1999,6 +2056,9 @@ SDValue DAGCombiner::visitSUB(SDNode *N) { N1.getNode()); } + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + ConstantSDNode *N1C = getAsNonOpaqueConstant(N1); // fold (sub x, c) -> (add x, -c) @@ -2210,6 +2270,10 @@ SDValue DAGCombiner::visitMUL(SDNode *N) { // fold (mul x, 1) -> x if (N1IsConst && ConstValue1 == 1 && IsFullSplat) return N0; + + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + // fold (mul x, -1) -> 0-x if (N1IsConst && ConstValue1.isAllOnesValue()) { SDLoc DL(N); @@ -2401,6 +2465,9 @@ SDValue DAGCombiner::visitSDIV(SDNode *N) { return DAG.getNode(ISD::SUB, DL, VT, DAG.getConstant(0, DL, VT), N0); + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + // If we know the sign bits of both operands are zero, strength reduce to a // udiv instead. Handles (X&15) /s 4 -> X&15 >> 2 if (DAG.SignBitIsZero(N1) && DAG.SignBitIsZero(N0)) @@ -2493,6 +2560,9 @@ SDValue DAGCombiner::visitUDIV(SDNode *N) { N0C, N1C)) return Folded; + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + // fold (udiv x, (1 << c)) -> x >>u c if (isConstantOrConstantVector(N1, /*NoOpaques*/ true) && DAG.isKnownToBeAPowerOfTwo(N1)) { @@ -2561,6 +2631,9 @@ SDValue DAGCombiner::visitREM(SDNode *N) { if (SDValue Folded = DAG.FoldConstantArithmetic(Opcode, DL, VT, N0C, N1C)) return Folded; + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + if (isSigned) { // If we know the sign bits of both operands are zero, strength reduce to a // urem instead. Handles (X & 0x0FFFFFFF) %s 16 -> X&15 @@ -3267,6 +3340,10 @@ SDValue DAGCombiner::visitAND(SDNode *N) { if (N1C && DAG.MaskedValueIsZero(SDValue(N, 0), APInt::getAllOnesValue(BitWidth))) return DAG.getConstant(0, SDLoc(N), VT); + + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + // reassociate and if (SDValue RAND = ReassociateOps(ISD::AND, SDLoc(N), N0, N1)) return RAND; @@ -4008,6 +4085,10 @@ SDValue DAGCombiner::visitOR(SDNode *N) { // fold (or x, -1) -> -1 if (isAllOnesConstant(N1)) return N1; + + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + // fold (or x, c) -> c iff (x & ~c) == 0 if (N1C && DAG.MaskedValueIsZero(N0, ~N1C->getAPIntValue())) return N1; @@ -4753,6 +4834,10 @@ SDValue DAGCombiner::visitXOR(SDNode *N) { // fold (xor x, 0) -> x if (isNullConstant(N1)) return N0; + + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + // reassociate xor if (SDValue RXOR = ReassociateOps(ISD::XOR, SDLoc(N), N0, N1)) return RXOR; @@ -5040,6 +5125,10 @@ SDValue DAGCombiner::visitSHL(SDNode *N) { // fold (shl undef, x) -> 0 if (N0.isUndef()) return DAG.getConstant(0, SDLoc(N), VT); + + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + // if (shl x, c) is known to be zero, return 0 if (DAG.MaskedValueIsZero(SDValue(N, 0), APInt::getAllOnesValue(OpSizeInBits))) @@ -5243,6 +5332,10 @@ SDValue DAGCombiner::visitSRA(SDNode *N) { // fold (sra x, 0) -> x if (N1C && N1C->isNullValue()) return N0; + + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + // fold (sra (shl x, c1), c1) -> sext_inreg for some c1 and target supports // sext_inreg. if (N1C && N0.getOpcode() == ISD::SHL && N1 == N0.getOperand(1)) { @@ -5390,6 +5483,10 @@ SDValue DAGCombiner::visitSRL(SDNode *N) { // fold (srl x, 0) -> x if (N1C && N1C->isNullValue()) return N0; + + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + // if (srl x, c) is known to be zero, return 0 if (N1C && DAG.MaskedValueIsZero(SDValue(N, 0), APInt::getAllOnesValue(OpSizeInBits))) @@ -9064,6 +9161,9 @@ SDValue DAGCombiner::visitFADD(SDNode *N) { if (N0CFP && !N1CFP) return DAG.getNode(ISD::FADD, DL, VT, N1, N0, Flags); + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + // fold (fadd A, (fneg B)) -> (fsub A, B) if ((!LegalOperations || TLI.isOperationLegalOrCustom(ISD::FSUB, VT)) && isNegatibleForFree(N1, LegalOperations, TLI, &Options) == 2) @@ -9211,6 +9311,9 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) { if (N0CFP && N1CFP) return DAG.getNode(ISD::FSUB, DL, VT, N0, N1, Flags); + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + // fold (fsub A, (fneg B)) -> (fadd A, B) if (isNegatibleForFree(N1, LegalOperations, TLI, &Options)) return DAG.getNode(ISD::FADD, DL, VT, N0, @@ -9290,6 +9393,9 @@ SDValue DAGCombiner::visitFMUL(SDNode *N) { if (N1CFP && N1CFP->isExactlyValue(1.0)) return N0; + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + if (Options.UnsafeFPMath) { // fold (fmul A, 0) -> 0 if (N1CFP && N1CFP->isZero()) @@ -9544,6 +9650,9 @@ SDValue DAGCombiner::visitFDIV(SDNode *N) { if (N0CFP && N1CFP) return DAG.getNode(ISD::FDIV, SDLoc(N), VT, N0, N1, Flags); + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + if (Options.UnsafeFPMath) { // fold (fdiv X, c2) -> fmul X, 1/c2 if losing precision is acceptable. if (N1CFP) { @@ -9647,6 +9756,9 @@ SDValue DAGCombiner::visitFREM(SDNode *N) { return DAG.getNode(ISD::FREM, SDLoc(N), VT, N0, N1, &cast<BinaryWithFlagsSDNode>(N)->Flags); + if (SDValue NewSel = foldBinOpIntoSelect(N)) + return NewSel; + return SDValue(); } |
