Index: lib/Transforms/InstCombine/InstCombineSelect.cpp =================================================================== --- lib/Transforms/InstCombine/InstCombineSelect.cpp +++ lib/Transforms/InstCombine/InstCombineSelect.cpp @@ -61,23 +61,37 @@ /// To /// %C = select i1 %A, i8 %z, i8 %y /// OP: binop with an identity constant -/// TODO: support for non-commutative and FP opcodes +// TODO: support for undefs static Instruction *foldSelectBinOpIdentity(SelectInst &Sel) { - Value *Cond = Sel.getCondition(); Value *X, *Z; Constant *C; CmpInst::Predicate Pred; - if (!match(Cond, m_ICmp(Pred, m_Value(X), m_Constant(C))) || - !ICmpInst::isEquality(Pred)) + if (!match(Cond, m_Cmp(Pred, m_Value(X), m_Constant(C)))) + return nullptr; + + bool IsEq; + if (ICmpInst::isEquality(Pred)) { + IsEq = Pred == ICmpInst::ICMP_EQ; + } else if (FCmpInst::isEquality(Pred)) { + IsEq = Pred == FCmpInst::FCMP_OEQ || Pred == FCmpInst::FCMP_UEQ; + } else { return nullptr; + } - bool IsEq = Pred == ICmpInst::ICMP_EQ; auto *BO = dyn_cast(IsEq ? Sel.getTrueValue() : Sel.getFalseValue()); - // TODO: support for undefs - if (BO && match(BO, m_c_BinOp(m_Specific(X), m_Value(Z))) && - ConstantExpr::getBinOpIdentity(BO->getOpcode(), X->getType()) == C) { + if (!BO) + return nullptr; + + if (match(BO, m_c_BinOp(m_Specific(X), m_Value(Z))) && + ConstantExpr::getBinOpIdentity(BO->getOpcode(), X->getType()) == + C) { + Sel.setOperand(IsEq ? 1 : 2, Z); + return &Sel; + } else if (match(BO, m_BinOp(m_Specific(X), m_Value(Z))) && + ConstantExpr::getBinOpIdentity(BO->getOpcode(), X->getType(), + true) == C) { Sel.setOperand(IsEq ? 1 : 2, Z); return &Sel; } @@ -86,7 +100,8 @@ /// This folds: /// select (icmp eq (and X, C1)), TC, FC -/// iff C1 is a power 2 and the difference between TC and FC is a power-of-2. +/// iff C1 is a power 2 and the difference between TC and FC is a +/// power-of-2. /// To something like: /// (shr (and (X, C1)), (log2(C1) - log2(TC-FC))) + FC /// Or: @@ -119,8 +134,8 @@ return nullptr; AndMask = *AndRHS; - } else if (decomposeBitTestICmp(Cmp->getOperand(0), Cmp->getOperand(1), - Pred, V, AndMask)) { + } else if (decomposeBitTestICmp(Cmp->getOperand(0), Cmp->getOperand(1), Pred, + V, AndMask)) { assert(ICmpInst::isEquality(Pred) && "Not equality test?"); if (!AndMask.isPowerOf2()) return nullptr; @@ -139,7 +154,8 @@ if (!TC.isNullValue() && !FC.isNullValue()) { // If the select constants differ by exactly one bit and that's the same // bit that is masked and checked by the select condition, the select can - // be replaced by bitwise logic to set/clear one bit of the constant result. + // be replaced by bitwise logic to set/clear one bit of the constant + // result. if (TC.getBitWidth() != AndMask.getBitWidth() || (TC ^ FC) != AndMask) return nullptr; if (CreateAnd) { @@ -181,7 +197,8 @@ if (CreateAnd) V = Builder.CreateAnd(V, ConstantInt::get(V->getType(), AndMask)); - // If types don't match, we can still convert the select by introducing a zext + // If types don't match, we can still convert the select by introducing a + // zext // or a trunc of the 'and'. if (ValZeros > AndZeros) { V = Builder.CreateZExtOrTrunc(V, SelType); @@ -193,7 +210,8 @@ V = Builder.CreateZExtOrTrunc(V, SelType); } - // Okay, now we know that everything is set up, we just don't know whether we + // Okay, now we know that everything is set up, we just don't know whether + // we // have a icmp_ne or icmp_eq and whether the true or false val is the zero. bool ShouldNotVal = !TC.isNullValue(); ShouldNotVal ^= Pred == ICmpInst::ICMP_NE; @@ -201,1798 +219,1843 @@ V = Builder.CreateXor(V, ValC); return V; -} - -/// We want to turn code that looks like this: -/// %C = or %A, %B -/// %D = select %cond, %C, %A -/// into: -/// %C = select %cond, %B, 0 -/// %D = or %A, %C -/// -/// Assuming that the specified instruction is an operand to the select, return -/// a bitmask indicating which operands of this instruction are foldable if they -/// equal the other incoming value of the select. -static unsigned getSelectFoldableOperands(BinaryOperator *I) { - switch (I->getOpcode()) { - case Instruction::Add: - case Instruction::Mul: - case Instruction::And: - case Instruction::Or: - case Instruction::Xor: - return 3; // Can fold through either operand. - case Instruction::Sub: // Can only fold on the amount subtracted. - case Instruction::Shl: // Can only fold on the shift amount. - case Instruction::LShr: - case Instruction::AShr: - return 1; - default: - return 0; // Cannot fold } -} -/// For the same transformation as the previous function, return the identity -/// constant that goes into the select. -static APInt getSelectFoldableConstant(BinaryOperator *I) { - switch (I->getOpcode()) { - default: llvm_unreachable("This cannot happen!"); - case Instruction::Add: - case Instruction::Sub: - case Instruction::Or: - case Instruction::Xor: - case Instruction::Shl: - case Instruction::LShr: - case Instruction::AShr: - return APInt::getNullValue(I->getType()->getScalarSizeInBits()); - case Instruction::And: - return APInt::getAllOnesValue(I->getType()->getScalarSizeInBits()); - case Instruction::Mul: - return APInt(I->getType()->getScalarSizeInBits(), 1); + /// We want to turn code that looks like this: + /// %C = or %A, %B + /// %D = select %cond, %C, %A + /// into: + /// %C = select %cond, %B, 0 + /// %D = or %A, %C + /// + /// Assuming that the specified instruction is an operand to the select, + /// return + /// a bitmask indicating which operands of this instruction are foldable if + /// they + /// equal the other incoming value of the select. + static unsigned getSelectFoldableOperands(BinaryOperator * I) { + switch (I->getOpcode()) { + case Instruction::Add: + case Instruction::Mul: + case Instruction::And: + case Instruction::Or: + case Instruction::Xor: + return 3; // Can fold through either operand. + case Instruction::Sub: // Can only fold on the amount subtracted. + case Instruction::Shl: // Can only fold on the shift amount. + case Instruction::LShr: + case Instruction::AShr: + return 1; + default: + return 0; // Cannot fold + } } -} -/// We have (select c, TI, FI), and we know that TI and FI have the same opcode. -Instruction *InstCombiner::foldSelectOpOp(SelectInst &SI, Instruction *TI, - Instruction *FI) { - // Don't break up min/max patterns. The hasOneUse checks below prevent that - // for most cases, but vector min/max with bitcasts can be transformed. If the - // one-use restrictions are eased for other patterns, we still don't want to - // obfuscate min/max. - if ((match(&SI, m_SMin(m_Value(), m_Value())) || - match(&SI, m_SMax(m_Value(), m_Value())) || - match(&SI, m_UMin(m_Value(), m_Value())) || - match(&SI, m_UMax(m_Value(), m_Value())))) - return nullptr; + /// For the same transformation as the previous function, return the identity + /// constant that goes into the select. + static APInt getSelectFoldableConstant(BinaryOperator * I) { + switch (I->getOpcode()) { + default: + llvm_unreachable("This cannot happen!"); + case Instruction::Add: + case Instruction::Sub: + case Instruction::Or: + case Instruction::Xor: + case Instruction::Shl: + case Instruction::LShr: + case Instruction::AShr: + return APInt::getNullValue(I->getType()->getScalarSizeInBits()); + case Instruction::And: + return APInt::getAllOnesValue(I->getType()->getScalarSizeInBits()); + case Instruction::Mul: + return APInt(I->getType()->getScalarSizeInBits(), 1); + } + } - // If this is a cast from the same type, merge. - if (TI->getNumOperands() == 1 && TI->isCast()) { - Type *FIOpndTy = FI->getOperand(0)->getType(); - if (TI->getOperand(0)->getType() != FIOpndTy) + /// We have (select c, TI, FI), and we know that TI and FI have the same + /// opcode. + Instruction *InstCombiner::foldSelectOpOp(SelectInst & SI, Instruction * TI, + Instruction * FI) { + // Don't break up min/max patterns. The hasOneUse checks below prevent that + // for most cases, but vector min/max with bitcasts can be transformed. If + // the + // one-use restrictions are eased for other patterns, we still don't want to + // obfuscate min/max. + if ((match(&SI, m_SMin(m_Value(), m_Value())) || + match(&SI, m_SMax(m_Value(), m_Value())) || + match(&SI, m_UMin(m_Value(), m_Value())) || + match(&SI, m_UMax(m_Value(), m_Value())))) return nullptr; - // The select condition may be a vector. We may only change the operand - // type if the vector width remains the same (and matches the condition). - Type *CondTy = SI.getCondition()->getType(); - if (CondTy->isVectorTy()) { - if (!FIOpndTy->isVectorTy()) - return nullptr; - if (CondTy->getVectorNumElements() != FIOpndTy->getVectorNumElements()) + // If this is a cast from the same type, merge. + if (TI->getNumOperands() == 1 && TI->isCast()) { + Type *FIOpndTy = FI->getOperand(0)->getType(); + if (TI->getOperand(0)->getType() != FIOpndTy) return nullptr; - // TODO: If the backend knew how to deal with casts better, we could - // remove this limitation. For now, there's too much potential to create - // worse codegen by promoting the select ahead of size-altering casts - // (PR28160). - // - // Note that ValueTracking's matchSelectPattern() looks through casts - // without checking 'hasOneUse' when it matches min/max patterns, so this - // transform may end up happening anyway. - if (TI->getOpcode() != Instruction::BitCast && - (!TI->hasOneUse() || !FI->hasOneUse())) + // The select condition may be a vector. We may only change the operand + // type if the vector width remains the same (and matches the condition). + Type *CondTy = SI.getCondition()->getType(); + if (CondTy->isVectorTy()) { + if (!FIOpndTy->isVectorTy()) + return nullptr; + if (CondTy->getVectorNumElements() != FIOpndTy->getVectorNumElements()) + return nullptr; + + // TODO: If the backend knew how to deal with casts better, we could + // remove this limitation. For now, there's too much potential to create + // worse codegen by promoting the select ahead of size-altering casts + // (PR28160). + // + // Note that ValueTracking's matchSelectPattern() looks through casts + // without checking 'hasOneUse' when it matches min/max patterns, so + // this + // transform may end up happening anyway. + if (TI->getOpcode() != Instruction::BitCast && + (!TI->hasOneUse() || !FI->hasOneUse())) + return nullptr; + } else if (!TI->hasOneUse() || !FI->hasOneUse()) { + // TODO: The one-use restrictions for a scalar select could be eased if + // the fold of a select in visitLoadInst() was enhanced to match a + // pattern + // that includes a cast. return nullptr; - } else if (!TI->hasOneUse() || !FI->hasOneUse()) { - // TODO: The one-use restrictions for a scalar select could be eased if - // the fold of a select in visitLoadInst() was enhanced to match a pattern - // that includes a cast. + } + + // Fold this by inserting a select from the input values. + Value *NewSI = + Builder.CreateSelect(SI.getCondition(), TI->getOperand(0), + FI->getOperand(0), SI.getName() + ".v", &SI); + return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI, + TI->getType()); + } + + // Only handle binary operators (including two-operand getelementptr) with + // one-use here. As with the cast case above, it may be possible to relax + // the + // one-use constraint, but that needs be examined carefully since it may not + // reduce the total number of instructions. + if (TI->getNumOperands() != 2 || FI->getNumOperands() != 2 || + (!isa(TI) && !isa(TI)) || + !TI->hasOneUse() || !FI->hasOneUse()) return nullptr; - } - // Fold this by inserting a select from the input values. - Value *NewSI = - Builder.CreateSelect(SI.getCondition(), TI->getOperand(0), - FI->getOperand(0), SI.getName() + ".v", &SI); - return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI, - TI->getType()); - } - - // Only handle binary operators (including two-operand getelementptr) with - // one-use here. As with the cast case above, it may be possible to relax the - // one-use constraint, but that needs be examined carefully since it may not - // reduce the total number of instructions. - if (TI->getNumOperands() != 2 || FI->getNumOperands() != 2 || - (!isa(TI) && !isa(TI)) || - !TI->hasOneUse() || !FI->hasOneUse()) - return nullptr; + // Figure out if the operations have any operands in common. + Value *MatchOp, *OtherOpT, *OtherOpF; + bool MatchIsOpZero; + if (TI->getOperand(0) == FI->getOperand(0)) { + MatchOp = TI->getOperand(0); + OtherOpT = TI->getOperand(1); + OtherOpF = FI->getOperand(1); + MatchIsOpZero = true; + } else if (TI->getOperand(1) == FI->getOperand(1)) { + MatchOp = TI->getOperand(1); + OtherOpT = TI->getOperand(0); + OtherOpF = FI->getOperand(0); + MatchIsOpZero = false; + } else if (!TI->isCommutative()) { + return nullptr; + } else if (TI->getOperand(0) == FI->getOperand(1)) { + MatchOp = TI->getOperand(0); + OtherOpT = TI->getOperand(1); + OtherOpF = FI->getOperand(0); + MatchIsOpZero = true; + } else if (TI->getOperand(1) == FI->getOperand(0)) { + MatchOp = TI->getOperand(1); + OtherOpT = TI->getOperand(0); + OtherOpF = FI->getOperand(1); + MatchIsOpZero = true; + } else { + return nullptr; + } - // Figure out if the operations have any operands in common. - Value *MatchOp, *OtherOpT, *OtherOpF; - bool MatchIsOpZero; - if (TI->getOperand(0) == FI->getOperand(0)) { - MatchOp = TI->getOperand(0); - OtherOpT = TI->getOperand(1); - OtherOpF = FI->getOperand(1); - MatchIsOpZero = true; - } else if (TI->getOperand(1) == FI->getOperand(1)) { - MatchOp = TI->getOperand(1); - OtherOpT = TI->getOperand(0); - OtherOpF = FI->getOperand(0); - MatchIsOpZero = false; - } else if (!TI->isCommutative()) { - return nullptr; - } else if (TI->getOperand(0) == FI->getOperand(1)) { - MatchOp = TI->getOperand(0); - OtherOpT = TI->getOperand(1); - OtherOpF = FI->getOperand(0); - MatchIsOpZero = true; - } else if (TI->getOperand(1) == FI->getOperand(0)) { - MatchOp = TI->getOperand(1); - OtherOpT = TI->getOperand(0); - OtherOpF = FI->getOperand(1); - MatchIsOpZero = true; - } else { + // If we reach here, they do have operations in common. + Value *NewSI = Builder.CreateSelect(SI.getCondition(), OtherOpT, OtherOpF, + SI.getName() + ".v", &SI); + Value *Op0 = MatchIsOpZero ? MatchOp : NewSI; + Value *Op1 = MatchIsOpZero ? NewSI : MatchOp; + if (auto *BO = dyn_cast(TI)) { + return BinaryOperator::Create(BO->getOpcode(), Op0, Op1); + } + if (auto *TGEP = dyn_cast(TI)) { + auto *FGEP = cast(FI); + Type *ElementType = TGEP->getResultElementType(); + return TGEP->isInBounds() && FGEP->isInBounds() + ? GetElementPtrInst::CreateInBounds(ElementType, Op0, {Op1}) + : GetElementPtrInst::Create(ElementType, Op0, {Op1}); + } + llvm_unreachable("Expected BinaryOperator or GEP"); return nullptr; } - // If we reach here, they do have operations in common. - Value *NewSI = Builder.CreateSelect(SI.getCondition(), OtherOpT, OtherOpF, - SI.getName() + ".v", &SI); - Value *Op0 = MatchIsOpZero ? MatchOp : NewSI; - Value *Op1 = MatchIsOpZero ? NewSI : MatchOp; - if (auto *BO = dyn_cast(TI)) { - return BinaryOperator::Create(BO->getOpcode(), Op0, Op1); - } - if (auto *TGEP = dyn_cast(TI)) { - auto *FGEP = cast(FI); - Type *ElementType = TGEP->getResultElementType(); - return TGEP->isInBounds() && FGEP->isInBounds() - ? GetElementPtrInst::CreateInBounds(ElementType, Op0, {Op1}) - : GetElementPtrInst::Create(ElementType, Op0, {Op1}); + static bool isSelect01(const APInt &C1I, const APInt &C2I) { + if (!C1I.isNullValue() && !C2I.isNullValue()) // One side must be zero. + return false; + return C1I.isOneValue() || C1I.isAllOnesValue() || C2I.isOneValue() || + C2I.isAllOnesValue(); } - llvm_unreachable("Expected BinaryOperator or GEP"); - return nullptr; -} -static bool isSelect01(const APInt &C1I, const APInt &C2I) { - if (!C1I.isNullValue() && !C2I.isNullValue()) // One side must be zero. - return false; - return C1I.isOneValue() || C1I.isAllOnesValue() || - C2I.isOneValue() || C2I.isAllOnesValue(); -} + /// Try to fold the select into one of the operands to allow further + /// optimization. + Instruction *InstCombiner::foldSelectIntoOp(SelectInst & SI, Value * TrueVal, + Value * FalseVal) { + // See the comment above GetSelectFoldableOperands for a description of the + // transformation we are doing here. + if (auto *TVI = dyn_cast(TrueVal)) { + if (TVI->hasOneUse() && !isa(FalseVal)) { + if (unsigned SFO = getSelectFoldableOperands(TVI)) { + unsigned OpToFold = 0; + if ((SFO & 1) && FalseVal == TVI->getOperand(0)) { + OpToFold = 1; + } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) { + OpToFold = 2; + } -/// Try to fold the select into one of the operands to allow further -/// optimization. -Instruction *InstCombiner::foldSelectIntoOp(SelectInst &SI, Value *TrueVal, - Value *FalseVal) { - // See the comment above GetSelectFoldableOperands for a description of the - // transformation we are doing here. - if (auto *TVI = dyn_cast(TrueVal)) { - if (TVI->hasOneUse() && !isa(FalseVal)) { - if (unsigned SFO = getSelectFoldableOperands(TVI)) { - unsigned OpToFold = 0; - if ((SFO & 1) && FalseVal == TVI->getOperand(0)) { - OpToFold = 1; - } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) { - OpToFold = 2; - } - - if (OpToFold) { - APInt CI = getSelectFoldableConstant(TVI); - Value *OOp = TVI->getOperand(2-OpToFold); - // Avoid creating select between 2 constants unless it's selecting - // between 0, 1 and -1. - const APInt *OOpC; - bool OOpIsAPInt = match(OOp, m_APInt(OOpC)); - if (!isa(OOp) || (OOpIsAPInt && isSelect01(CI, *OOpC))) { - Value *C = ConstantInt::get(OOp->getType(), CI); - Value *NewSel = Builder.CreateSelect(SI.getCondition(), OOp, C); - NewSel->takeName(TVI); - BinaryOperator *BO = BinaryOperator::Create(TVI->getOpcode(), - FalseVal, NewSel); - BO->copyIRFlags(TVI); - return BO; + if (OpToFold) { + APInt CI = getSelectFoldableConstant(TVI); + Value *OOp = TVI->getOperand(2 - OpToFold); + // Avoid creating select between 2 constants unless it's selecting + // between 0, 1 and -1. + const APInt *OOpC; + bool OOpIsAPInt = match(OOp, m_APInt(OOpC)); + if (!isa(OOp) || (OOpIsAPInt && isSelect01(CI, *OOpC))) { + Value *C = ConstantInt::get(OOp->getType(), CI); + Value *NewSel = Builder.CreateSelect(SI.getCondition(), OOp, C); + NewSel->takeName(TVI); + BinaryOperator *BO = + BinaryOperator::Create(TVI->getOpcode(), FalseVal, NewSel); + BO->copyIRFlags(TVI); + return BO; + } } } } } - } - if (auto *FVI = dyn_cast(FalseVal)) { - if (FVI->hasOneUse() && !isa(TrueVal)) { - if (unsigned SFO = getSelectFoldableOperands(FVI)) { - unsigned OpToFold = 0; - if ((SFO & 1) && TrueVal == FVI->getOperand(0)) { - OpToFold = 1; - } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) { - OpToFold = 2; - } - - if (OpToFold) { - APInt CI = getSelectFoldableConstant(FVI); - Value *OOp = FVI->getOperand(2-OpToFold); - // Avoid creating select between 2 constants unless it's selecting - // between 0, 1 and -1. - const APInt *OOpC; - bool OOpIsAPInt = match(OOp, m_APInt(OOpC)); - if (!isa(OOp) || (OOpIsAPInt && isSelect01(CI, *OOpC))) { - Value *C = ConstantInt::get(OOp->getType(), CI); - Value *NewSel = Builder.CreateSelect(SI.getCondition(), C, OOp); - NewSel->takeName(FVI); - BinaryOperator *BO = BinaryOperator::Create(FVI->getOpcode(), - TrueVal, NewSel); - BO->copyIRFlags(FVI); - return BO; + if (auto *FVI = dyn_cast(FalseVal)) { + if (FVI->hasOneUse() && !isa(TrueVal)) { + if (unsigned SFO = getSelectFoldableOperands(FVI)) { + unsigned OpToFold = 0; + if ((SFO & 1) && TrueVal == FVI->getOperand(0)) { + OpToFold = 1; + } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) { + OpToFold = 2; + } + + if (OpToFold) { + APInt CI = getSelectFoldableConstant(FVI); + Value *OOp = FVI->getOperand(2 - OpToFold); + // Avoid creating select between 2 constants unless it's selecting + // between 0, 1 and -1. + const APInt *OOpC; + bool OOpIsAPInt = match(OOp, m_APInt(OOpC)); + if (!isa(OOp) || (OOpIsAPInt && isSelect01(CI, *OOpC))) { + Value *C = ConstantInt::get(OOp->getType(), CI); + Value *NewSel = Builder.CreateSelect(SI.getCondition(), C, OOp); + NewSel->takeName(FVI); + BinaryOperator *BO = + BinaryOperator::Create(FVI->getOpcode(), TrueVal, NewSel); + BO->copyIRFlags(FVI); + return BO; + } } } } } - } - - return nullptr; -} - -/// We want to turn: -/// (select (icmp eq (and X, Y), 0), (and (lshr X, Z), 1), 1) -/// into: -/// zext (icmp ne i32 (and X, (or Y, (shl 1, Z))), 0) -/// Note: -/// Z may be 0 if lshr is missing. -/// Worst-case scenario is that we will replace 5 instructions with 5 different -/// instructions, but we got rid of select. -static Instruction *foldSelectICmpAndAnd(Type *SelType, const ICmpInst *Cmp, - Value *TVal, Value *FVal, - InstCombiner::BuilderTy &Builder) { - if (!(Cmp->hasOneUse() && Cmp->getOperand(0)->hasOneUse() && - Cmp->getPredicate() == ICmpInst::ICMP_EQ && - match(Cmp->getOperand(1), m_Zero()) && match(FVal, m_One()))) - return nullptr; - - // The TrueVal has general form of: and %B, 1 - Value *B; - if (!match(TVal, m_OneUse(m_And(m_Value(B), m_One())))) - return nullptr; - - // Where %B may be optionally shifted: lshr %X, %Z. - Value *X, *Z; - const bool HasShift = match(B, m_OneUse(m_LShr(m_Value(X), m_Value(Z)))); - if (!HasShift) - X = B; - - Value *Y; - if (!match(Cmp->getOperand(0), m_c_And(m_Specific(X), m_Value(Y)))) - return nullptr; - // ((X & Y) == 0) ? ((X >> Z) & 1) : 1 --> (X & (Y | (1 << Z))) != 0 - // ((X & Y) == 0) ? (X & 1) : 1 --> (X & (Y | 1)) != 0 - Constant *One = ConstantInt::get(SelType, 1); - Value *MaskB = HasShift ? Builder.CreateShl(One, Z) : One; - Value *FullMask = Builder.CreateOr(Y, MaskB); - Value *MaskedX = Builder.CreateAnd(X, FullMask); - Value *ICmpNeZero = Builder.CreateIsNotNull(MaskedX); - return new ZExtInst(ICmpNeZero, SelType); -} - -/// We want to turn: -/// (select (icmp eq (and X, C1), 0), Y, (or Y, C2)) -/// into: -/// (or (shl (and X, C1), C3), Y) -/// iff: -/// C1 and C2 are both powers of 2 -/// where: -/// C3 = Log(C2) - Log(C1) -/// -/// This transform handles cases where: -/// 1. The icmp predicate is inverted -/// 2. The select operands are reversed -/// 3. The magnitude of C2 and C1 are flipped -static Value *foldSelectICmpAndOr(const ICmpInst *IC, Value *TrueVal, - Value *FalseVal, - InstCombiner::BuilderTy &Builder) { - // Only handle integer compares. Also, if this is a vector select, we need a - // vector compare. - if (!TrueVal->getType()->isIntOrIntVectorTy() || - TrueVal->getType()->isVectorTy() != IC->getType()->isVectorTy()) return nullptr; + } - Value *CmpLHS = IC->getOperand(0); - Value *CmpRHS = IC->getOperand(1); - - Value *V; - unsigned C1Log; - bool IsEqualZero; - bool NeedAnd = false; - if (IC->isEquality()) { - if (!match(CmpRHS, m_Zero())) + /// We want to turn: + /// (select (icmp eq (and X, Y), 0), (and (lshr X, Z), 1), 1) + /// into: + /// zext (icmp ne i32 (and X, (or Y, (shl 1, Z))), 0) + /// Note: + /// Z may be 0 if lshr is missing. + /// Worst-case scenario is that we will replace 5 instructions with 5 + /// different + /// instructions, but we got rid of select. + static Instruction *foldSelectICmpAndAnd(Type * SelType, const ICmpInst *Cmp, + Value *TVal, Value *FVal, + InstCombiner::BuilderTy &Builder) { + if (!(Cmp->hasOneUse() && Cmp->getOperand(0)->hasOneUse() && + Cmp->getPredicate() == ICmpInst::ICMP_EQ && + match(Cmp->getOperand(1), m_Zero()) && match(FVal, m_One()))) return nullptr; - const APInt *C1; - if (!match(CmpLHS, m_And(m_Value(), m_Power2(C1)))) + // The TrueVal has general form of: and %B, 1 + Value *B; + if (!match(TVal, m_OneUse(m_And(m_Value(B), m_One())))) return nullptr; - V = CmpLHS; - C1Log = C1->logBase2(); - IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_EQ; - } else if (IC->getPredicate() == ICmpInst::ICMP_SLT || - IC->getPredicate() == ICmpInst::ICMP_SGT) { - // We also need to recognize (icmp slt (trunc (X)), 0) and - // (icmp sgt (trunc (X)), -1). - IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_SGT; - if ((IsEqualZero && !match(CmpRHS, m_AllOnes())) || - (!IsEqualZero && !match(CmpRHS, m_Zero()))) + // Where %B may be optionally shifted: lshr %X, %Z. + Value *X, *Z; + const bool HasShift = match(B, m_OneUse(m_LShr(m_Value(X), m_Value(Z)))); + if (!HasShift) + X = B; + + Value *Y; + if (!match(Cmp->getOperand(0), m_c_And(m_Specific(X), m_Value(Y)))) return nullptr; - if (!match(CmpLHS, m_OneUse(m_Trunc(m_Value(V))))) + // ((X & Y) == 0) ? ((X >> Z) & 1) : 1 --> (X & (Y | (1 << Z))) != 0 + // ((X & Y) == 0) ? (X & 1) : 1 --> (X & (Y | 1)) != 0 + Constant *One = ConstantInt::get(SelType, 1); + Value *MaskB = HasShift ? Builder.CreateShl(One, Z) : One; + Value *FullMask = Builder.CreateOr(Y, MaskB); + Value *MaskedX = Builder.CreateAnd(X, FullMask); + Value *ICmpNeZero = Builder.CreateIsNotNull(MaskedX); + return new ZExtInst(ICmpNeZero, SelType); + } + + /// We want to turn: + /// (select (icmp eq (and X, C1), 0), Y, (or Y, C2)) + /// into: + /// (or (shl (and X, C1), C3), Y) + /// iff: + /// C1 and C2 are both powers of 2 + /// where: + /// C3 = Log(C2) - Log(C1) + /// + /// This transform handles cases where: + /// 1. The icmp predicate is inverted + /// 2. The select operands are reversed + /// 3. The magnitude of C2 and C1 are flipped + static Value *foldSelectICmpAndOr(const ICmpInst *IC, Value *TrueVal, + Value *FalseVal, + InstCombiner::BuilderTy &Builder) { + // Only handle integer compares. Also, if this is a vector select, we need a + // vector compare. + if (!TrueVal->getType()->isIntOrIntVectorTy() || + TrueVal->getType()->isVectorTy() != IC->getType()->isVectorTy()) return nullptr; - C1Log = CmpLHS->getType()->getScalarSizeInBits() - 1; - NeedAnd = true; - } else { - return nullptr; - } + Value *CmpLHS = IC->getOperand(0); + Value *CmpRHS = IC->getOperand(1); - const APInt *C2; - bool OrOnTrueVal = false; - bool OrOnFalseVal = match(FalseVal, m_Or(m_Specific(TrueVal), m_Power2(C2))); - if (!OrOnFalseVal) - OrOnTrueVal = match(TrueVal, m_Or(m_Specific(FalseVal), m_Power2(C2))); + Value *V; + unsigned C1Log; + bool IsEqualZero; + bool NeedAnd = false; + if (IC->isEquality()) { + if (!match(CmpRHS, m_Zero())) + return nullptr; - if (!OrOnFalseVal && !OrOnTrueVal) - return nullptr; + const APInt *C1; + if (!match(CmpLHS, m_And(m_Value(), m_Power2(C1)))) + return nullptr; - Value *Y = OrOnFalseVal ? TrueVal : FalseVal; + V = CmpLHS; + C1Log = C1->logBase2(); + IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_EQ; + } else if (IC->getPredicate() == ICmpInst::ICMP_SLT || + IC->getPredicate() == ICmpInst::ICMP_SGT) { + // We also need to recognize (icmp slt (trunc (X)), 0) and + // (icmp sgt (trunc (X)), -1). + IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_SGT; + if ((IsEqualZero && !match(CmpRHS, m_AllOnes())) || + (!IsEqualZero && !match(CmpRHS, m_Zero()))) + return nullptr; - unsigned C2Log = C2->logBase2(); + if (!match(CmpLHS, m_OneUse(m_Trunc(m_Value(V))))) + return nullptr; - bool NeedXor = (!IsEqualZero && OrOnFalseVal) || (IsEqualZero && OrOnTrueVal); - bool NeedShift = C1Log != C2Log; - bool NeedZExtTrunc = Y->getType()->getScalarSizeInBits() != - V->getType()->getScalarSizeInBits(); - - // Make sure we don't create more instructions than we save. - Value *Or = OrOnFalseVal ? FalseVal : TrueVal; - if ((NeedShift + NeedXor + NeedZExtTrunc) > - (IC->hasOneUse() + Or->hasOneUse())) - return nullptr; + C1Log = CmpLHS->getType()->getScalarSizeInBits() - 1; + NeedAnd = true; + } else { + return nullptr; + } - if (NeedAnd) { - // Insert the AND instruction on the input to the truncate. - APInt C1 = APInt::getOneBitSet(V->getType()->getScalarSizeInBits(), C1Log); - V = Builder.CreateAnd(V, ConstantInt::get(V->getType(), C1)); - } - - if (C2Log > C1Log) { - V = Builder.CreateZExtOrTrunc(V, Y->getType()); - V = Builder.CreateShl(V, C2Log - C1Log); - } else if (C1Log > C2Log) { - V = Builder.CreateLShr(V, C1Log - C2Log); - V = Builder.CreateZExtOrTrunc(V, Y->getType()); - } else - V = Builder.CreateZExtOrTrunc(V, Y->getType()); + const APInt *C2; + bool OrOnTrueVal = false; + bool OrOnFalseVal = + match(FalseVal, m_Or(m_Specific(TrueVal), m_Power2(C2))); + if (!OrOnFalseVal) + OrOnTrueVal = match(TrueVal, m_Or(m_Specific(FalseVal), m_Power2(C2))); - if (NeedXor) - V = Builder.CreateXor(V, *C2); + if (!OrOnFalseVal && !OrOnTrueVal) + return nullptr; - return Builder.CreateOr(V, Y); -} + Value *Y = OrOnFalseVal ? TrueVal : FalseVal; -/// Transform patterns such as: (a > b) ? a - b : 0 -/// into: ((a > b) ? a : b) - b) -/// This produces a canonical max pattern that is more easily recognized by the -/// backend and converted into saturated subtraction instructions if those -/// exist. -/// There are 8 commuted/swapped variants of this pattern. -/// TODO: Also support a - UMIN(a,b) patterns. -static Value *canonicalizeSaturatedSubtract(const ICmpInst *ICI, - const Value *TrueVal, - const Value *FalseVal, - InstCombiner::BuilderTy &Builder) { - ICmpInst::Predicate Pred = ICI->getPredicate(); - if (!ICmpInst::isUnsigned(Pred)) - return nullptr; + unsigned C2Log = C2->logBase2(); - // (b > a) ? 0 : a - b -> (b <= a) ? a - b : 0 - if (match(TrueVal, m_Zero())) { - Pred = ICmpInst::getInversePredicate(Pred); - std::swap(TrueVal, FalseVal); - } - if (!match(FalseVal, m_Zero())) - return nullptr; + bool NeedXor = + (!IsEqualZero && OrOnFalseVal) || (IsEqualZero && OrOnTrueVal); + bool NeedShift = C1Log != C2Log; + bool NeedZExtTrunc = Y->getType()->getScalarSizeInBits() != + V->getType()->getScalarSizeInBits(); + + // Make sure we don't create more instructions than we save. + Value *Or = OrOnFalseVal ? FalseVal : TrueVal; + if ((NeedShift + NeedXor + NeedZExtTrunc) > + (IC->hasOneUse() + Or->hasOneUse())) + return nullptr; - Value *A = ICI->getOperand(0); - Value *B = ICI->getOperand(1); - if (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_ULT) { - // (b < a) ? a - b : 0 -> (a > b) ? a - b : 0 - std::swap(A, B); - Pred = ICmpInst::getSwappedPredicate(Pred); - } + if (NeedAnd) { + // Insert the AND instruction on the input to the truncate. + APInt C1 = + APInt::getOneBitSet(V->getType()->getScalarSizeInBits(), C1Log); + V = Builder.CreateAnd(V, ConstantInt::get(V->getType(), C1)); + } + + if (C2Log > C1Log) { + V = Builder.CreateZExtOrTrunc(V, Y->getType()); + V = Builder.CreateShl(V, C2Log - C1Log); + } else if (C1Log > C2Log) { + V = Builder.CreateLShr(V, C1Log - C2Log); + V = Builder.CreateZExtOrTrunc(V, Y->getType()); + } else + V = Builder.CreateZExtOrTrunc(V, Y->getType()); + + if (NeedXor) + V = Builder.CreateXor(V, *C2); + + return Builder.CreateOr(V, Y); + } + + /// Transform patterns such as: (a > b) ? a - b : 0 + /// into: ((a > b) ? a : b) - b) + /// This produces a canonical max pattern that is more easily recognized by + /// the + /// backend and converted into saturated subtraction instructions if those + /// exist. + /// There are 8 commuted/swapped variants of this pattern. + /// TODO: Also support a - UMIN(a,b) patterns. + static Value *canonicalizeSaturatedSubtract( + const ICmpInst *ICI, const Value *TrueVal, const Value *FalseVal, + InstCombiner::BuilderTy &Builder) { + ICmpInst::Predicate Pred = ICI->getPredicate(); + if (!ICmpInst::isUnsigned(Pred)) + return nullptr; + + // (b > a) ? 0 : a - b -> (b <= a) ? a - b : 0 + if (match(TrueVal, m_Zero())) { + Pred = ICmpInst::getInversePredicate(Pred); + std::swap(TrueVal, FalseVal); + } + if (!match(FalseVal, m_Zero())) + return nullptr; - assert((Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_UGT) && - "Unexpected isUnsigned predicate!"); + Value *A = ICI->getOperand(0); + Value *B = ICI->getOperand(1); + if (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_ULT) { + // (b < a) ? a - b : 0 -> (a > b) ? a - b : 0 + std::swap(A, B); + Pred = ICmpInst::getSwappedPredicate(Pred); + } + + assert((Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_UGT) && + "Unexpected isUnsigned predicate!"); + + // Account for swapped form of subtraction: ((a > b) ? b - a : 0). + bool IsNegative = false; + if (match(TrueVal, m_Sub(m_Specific(B), m_Specific(A)))) + IsNegative = true; + else if (!match(TrueVal, m_Sub(m_Specific(A), m_Specific(B)))) + return nullptr; - // Account for swapped form of subtraction: ((a > b) ? b - a : 0). - bool IsNegative = false; - if (match(TrueVal, m_Sub(m_Specific(B), m_Specific(A)))) - IsNegative = true; - else if (!match(TrueVal, m_Sub(m_Specific(A), m_Specific(B)))) - return nullptr; + // If sub is used anywhere else, we wouldn't be able to eliminate it + // afterwards. + if (!TrueVal->hasOneUse()) + return nullptr; - // If sub is used anywhere else, we wouldn't be able to eliminate it - // afterwards. - if (!TrueVal->hasOneUse()) - return nullptr; + // All checks passed, convert to canonical unsigned saturated subtraction + // form: sub(max()). + // (a > b) ? a - b : 0 -> ((a > b) ? a : b) - b) + Value *Max = Builder.CreateSelect(Builder.CreateICmp(Pred, A, B), A, B); + return IsNegative ? Builder.CreateSub(B, Max) : Builder.CreateSub(Max, B); + } + + /// Attempt to fold a cttz/ctlz followed by a icmp plus select into a single + /// call to cttz/ctlz with flag 'is_zero_undef' cleared. + /// + /// For example, we can fold the following code sequence: + /// \code + /// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 true) + /// %1 = icmp ne i32 %x, 0 + /// %2 = select i1 %1, i32 %0, i32 32 + /// \code + /// + /// into: + /// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 false) + static Value *foldSelectCttzCtlz(ICmpInst * ICI, Value * TrueVal, + Value * FalseVal, + InstCombiner::BuilderTy & Builder) { + ICmpInst::Predicate Pred = ICI->getPredicate(); + Value *CmpLHS = ICI->getOperand(0); + Value *CmpRHS = ICI->getOperand(1); - // All checks passed, convert to canonical unsigned saturated subtraction - // form: sub(max()). - // (a > b) ? a - b : 0 -> ((a > b) ? a : b) - b) - Value *Max = Builder.CreateSelect(Builder.CreateICmp(Pred, A, B), A, B); - return IsNegative ? Builder.CreateSub(B, Max) : Builder.CreateSub(Max, B); -} + // Check if the condition value compares a value for equality against zero. + if (!ICI->isEquality() || !match(CmpRHS, m_Zero())) + return nullptr; -/// Attempt to fold a cttz/ctlz followed by a icmp plus select into a single -/// call to cttz/ctlz with flag 'is_zero_undef' cleared. -/// -/// For example, we can fold the following code sequence: -/// \code -/// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 true) -/// %1 = icmp ne i32 %x, 0 -/// %2 = select i1 %1, i32 %0, i32 32 -/// \code -/// -/// into: -/// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 false) -static Value *foldSelectCttzCtlz(ICmpInst *ICI, Value *TrueVal, Value *FalseVal, - InstCombiner::BuilderTy &Builder) { - ICmpInst::Predicate Pred = ICI->getPredicate(); - Value *CmpLHS = ICI->getOperand(0); - Value *CmpRHS = ICI->getOperand(1); + Value *Count = FalseVal; + Value *ValueOnZero = TrueVal; + if (Pred == ICmpInst::ICMP_NE) + std::swap(Count, ValueOnZero); + + // Skip zero extend/truncate. + Value *V = nullptr; + if (match(Count, m_ZExt(m_Value(V))) || match(Count, m_Trunc(m_Value(V)))) + Count = V; + + // Check if the value propagated on zero is a constant number equal to the + // sizeof in bits of 'Count'. + unsigned SizeOfInBits = Count->getType()->getScalarSizeInBits(); + if (!match(ValueOnZero, m_SpecificInt(SizeOfInBits))) + return nullptr; - // Check if the condition value compares a value for equality against zero. - if (!ICI->isEquality() || !match(CmpRHS, m_Zero())) - return nullptr; + // Check that 'Count' is a call to intrinsic cttz/ctlz. Also check that the + // input to the cttz/ctlz is used as LHS for the compare instruction. + if (match(Count, m_Intrinsic(m_Specific(CmpLHS))) || + match(Count, m_Intrinsic(m_Specific(CmpLHS)))) { + IntrinsicInst *II = cast(Count); + // Explicitly clear the 'undef_on_zero' flag. + IntrinsicInst *NewI = cast(II->clone()); + NewI->setArgOperand(1, ConstantInt::getFalse(NewI->getContext())); + Builder.Insert(NewI); + return Builder.CreateZExtOrTrunc(NewI, ValueOnZero->getType()); + } - Value *Count = FalseVal; - Value *ValueOnZero = TrueVal; - if (Pred == ICmpInst::ICMP_NE) - std::swap(Count, ValueOnZero); - - // Skip zero extend/truncate. - Value *V = nullptr; - if (match(Count, m_ZExt(m_Value(V))) || - match(Count, m_Trunc(m_Value(V)))) - Count = V; - - // Check if the value propagated on zero is a constant number equal to the - // sizeof in bits of 'Count'. - unsigned SizeOfInBits = Count->getType()->getScalarSizeInBits(); - if (!match(ValueOnZero, m_SpecificInt(SizeOfInBits))) return nullptr; - - // Check that 'Count' is a call to intrinsic cttz/ctlz. Also check that the - // input to the cttz/ctlz is used as LHS for the compare instruction. - if (match(Count, m_Intrinsic(m_Specific(CmpLHS))) || - match(Count, m_Intrinsic(m_Specific(CmpLHS)))) { - IntrinsicInst *II = cast(Count); - // Explicitly clear the 'undef_on_zero' flag. - IntrinsicInst *NewI = cast(II->clone()); - NewI->setArgOperand(1, ConstantInt::getFalse(NewI->getContext())); - Builder.Insert(NewI); - return Builder.CreateZExtOrTrunc(NewI, ValueOnZero->getType()); } - return nullptr; -} - -/// Return true if we find and adjust an icmp+select pattern where the compare -/// is with a constant that can be incremented or decremented to match the -/// minimum or maximum idiom. -static bool adjustMinMax(SelectInst &Sel, ICmpInst &Cmp) { - ICmpInst::Predicate Pred = Cmp.getPredicate(); - Value *CmpLHS = Cmp.getOperand(0); - Value *CmpRHS = Cmp.getOperand(1); - Value *TrueVal = Sel.getTrueValue(); - Value *FalseVal = Sel.getFalseValue(); - - // We may move or edit the compare, so make sure the select is the only user. - const APInt *CmpC; - if (!Cmp.hasOneUse() || !match(CmpRHS, m_APInt(CmpC))) - return false; + /// Return true if we find and adjust an icmp+select pattern where the compare + /// is with a constant that can be incremented or decremented to match the + /// minimum or maximum idiom. + static bool adjustMinMax(SelectInst & Sel, ICmpInst & Cmp) { + ICmpInst::Predicate Pred = Cmp.getPredicate(); + Value *CmpLHS = Cmp.getOperand(0); + Value *CmpRHS = Cmp.getOperand(1); + Value *TrueVal = Sel.getTrueValue(); + Value *FalseVal = Sel.getFalseValue(); + + // We may move or edit the compare, so make sure the select is the only + // user. + const APInt *CmpC; + if (!Cmp.hasOneUse() || !match(CmpRHS, m_APInt(CmpC))) + return false; - // These transforms only work for selects of integers or vector selects of - // integer vectors. - Type *SelTy = Sel.getType(); - auto *SelEltTy = dyn_cast(SelTy->getScalarType()); - if (!SelEltTy || SelTy->isVectorTy() != Cmp.getType()->isVectorTy()) - return false; + // These transforms only work for selects of integers or vector selects of + // integer vectors. + Type *SelTy = Sel.getType(); + auto *SelEltTy = dyn_cast(SelTy->getScalarType()); + if (!SelEltTy || SelTy->isVectorTy() != Cmp.getType()->isVectorTy()) + return false; - Constant *AdjustedRHS; - if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SGT) - AdjustedRHS = ConstantInt::get(CmpRHS->getType(), *CmpC + 1); - else if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SLT) - AdjustedRHS = ConstantInt::get(CmpRHS->getType(), *CmpC - 1); - else - return false; + Constant *AdjustedRHS; + if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SGT) + AdjustedRHS = ConstantInt::get(CmpRHS->getType(), *CmpC + 1); + else if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SLT) + AdjustedRHS = ConstantInt::get(CmpRHS->getType(), *CmpC - 1); + else + return false; - // X > C ? X : C+1 --> X < C+1 ? C+1 : X - // X < C ? X : C-1 --> X > C-1 ? C-1 : X - if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) || - (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) { - ; // Nothing to do here. Values match without any sign/zero extension. - } - // Types do not match. Instead of calculating this with mixed types, promote - // all to the larger type. This enables scalar evolution to analyze this - // expression. - else if (CmpRHS->getType()->getScalarSizeInBits() < SelEltTy->getBitWidth()) { - Constant *SextRHS = ConstantExpr::getSExt(AdjustedRHS, SelTy); - - // X = sext x; x >s c ? X : C+1 --> X = sext x; X X = sext x; X >s C-1 ? C-1 : X - // X = sext x; x >u c ? X : C+1 --> X = sext x; X X = sext x; X >u C-1 ? C-1 : X - if (match(TrueVal, m_SExt(m_Specific(CmpLHS))) && SextRHS == FalseVal) { - CmpLHS = TrueVal; - AdjustedRHS = SextRHS; - } else if (match(FalseVal, m_SExt(m_Specific(CmpLHS))) && - SextRHS == TrueVal) { - CmpLHS = FalseVal; - AdjustedRHS = SextRHS; - } else if (Cmp.isUnsigned()) { - Constant *ZextRHS = ConstantExpr::getZExt(AdjustedRHS, SelTy); - // X = zext x; x >u c ? X : C+1 --> X = zext x; X X = zext x; X >u C-1 ? C-1 : X - // zext + signed compare cannot be changed: - // 0xff s 0x0000 - if (match(TrueVal, m_ZExt(m_Specific(CmpLHS))) && ZextRHS == FalseVal) { + // X > C ? X : C+1 --> X < C+1 ? C+1 : X + // X < C ? X : C-1 --> X > C-1 ? C-1 : X + if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) || + (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) { + ; // Nothing to do here. Values match without any sign/zero extension. + } + // Types do not match. Instead of calculating this with mixed types, promote + // all to the larger type. This enables scalar evolution to analyze this + // expression. + else if (CmpRHS->getType()->getScalarSizeInBits() < + SelEltTy->getBitWidth()) { + Constant *SextRHS = ConstantExpr::getSExt(AdjustedRHS, SelTy); + + // X = sext x; x >s c ? X : C+1 --> X = sext x; X X = sext x; X >s C-1 ? C-1 : X + // X = sext x; x >u c ? X : C+1 --> X = sext x; X X = sext x; X >u C-1 ? C-1 : X + if (match(TrueVal, m_SExt(m_Specific(CmpLHS))) && SextRHS == FalseVal) { CmpLHS = TrueVal; - AdjustedRHS = ZextRHS; - } else if (match(FalseVal, m_ZExt(m_Specific(CmpLHS))) && - ZextRHS == TrueVal) { + AdjustedRHS = SextRHS; + } else if (match(FalseVal, m_SExt(m_Specific(CmpLHS))) && + SextRHS == TrueVal) { CmpLHS = FalseVal; - AdjustedRHS = ZextRHS; + AdjustedRHS = SextRHS; + } else if (Cmp.isUnsigned()) { + Constant *ZextRHS = ConstantExpr::getZExt(AdjustedRHS, SelTy); + // X = zext x; x >u c ? X : C+1 --> X = zext x; X X = zext x; X >u C-1 ? C-1 : X + // zext + signed compare cannot be changed: + // 0xff s 0x0000 + if (match(TrueVal, m_ZExt(m_Specific(CmpLHS))) && ZextRHS == FalseVal) { + CmpLHS = TrueVal; + AdjustedRHS = ZextRHS; + } else if (match(FalseVal, m_ZExt(m_Specific(CmpLHS))) && + ZextRHS == TrueVal) { + CmpLHS = FalseVal; + AdjustedRHS = ZextRHS; + } else { + return false; + } } else { return false; } } else { return false; } - } else { - return false; - } - Pred = ICmpInst::getSwappedPredicate(Pred); - CmpRHS = AdjustedRHS; - std::swap(FalseVal, TrueVal); - Cmp.setPredicate(Pred); - Cmp.setOperand(0, CmpLHS); - Cmp.setOperand(1, CmpRHS); - Sel.setOperand(1, TrueVal); - Sel.setOperand(2, FalseVal); - Sel.swapProfMetadata(); - - // Move the compare instruction right before the select instruction. Otherwise - // the sext/zext value may be defined after the compare instruction uses it. - Cmp.moveBefore(&Sel); + Pred = ICmpInst::getSwappedPredicate(Pred); + CmpRHS = AdjustedRHS; + std::swap(FalseVal, TrueVal); + Cmp.setPredicate(Pred); + Cmp.setOperand(0, CmpLHS); + Cmp.setOperand(1, CmpRHS); + Sel.setOperand(1, TrueVal); + Sel.setOperand(2, FalseVal); + Sel.swapProfMetadata(); + + // Move the compare instruction right before the select instruction. + // Otherwise + // the sext/zext value may be defined after the compare instruction uses it. + Cmp.moveBefore(&Sel); - return true; -} + return true; + } -/// If this is an integer min/max (icmp + select) with a constant operand, -/// create the canonical icmp for the min/max operation and canonicalize the -/// constant to the 'false' operand of the select: -/// select (icmp Pred X, C1), C2, X --> select (icmp Pred' X, C2), X, C2 -/// Note: if C1 != C2, this will change the icmp constant to the existing -/// constant operand of the select. -static Instruction * -canonicalizeMinMaxWithConstant(SelectInst &Sel, ICmpInst &Cmp, - InstCombiner::BuilderTy &Builder) { - if (!Cmp.hasOneUse() || !isa(Cmp.getOperand(1))) - return nullptr; + /// If this is an integer min/max (icmp + select) with a constant operand, + /// create the canonical icmp for the min/max operation and canonicalize the + /// constant to the 'false' operand of the select: + /// select (icmp Pred X, C1), C2, X --> select (icmp Pred' X, C2), X, C2 + /// Note: if C1 != C2, this will change the icmp constant to the existing + /// constant operand of the select. + static Instruction *canonicalizeMinMaxWithConstant( + SelectInst & Sel, ICmpInst & Cmp, InstCombiner::BuilderTy & Builder) { + if (!Cmp.hasOneUse() || !isa(Cmp.getOperand(1))) + return nullptr; - // Canonicalize the compare predicate based on whether we have min or max. - Value *LHS, *RHS; - SelectPatternResult SPR = matchSelectPattern(&Sel, LHS, RHS); - if (!SelectPatternResult::isMinOrMax(SPR.Flavor)) - return nullptr; + // Canonicalize the compare predicate based on whether we have min or max. + Value *LHS, *RHS; + SelectPatternResult SPR = matchSelectPattern(&Sel, LHS, RHS); + if (!SelectPatternResult::isMinOrMax(SPR.Flavor)) + return nullptr; - // Is this already canonical? - ICmpInst::Predicate CanonicalPred = getMinMaxPred(SPR.Flavor); - if (Cmp.getOperand(0) == LHS && Cmp.getOperand(1) == RHS && - Cmp.getPredicate() == CanonicalPred) - return nullptr; + // Is this already canonical? + ICmpInst::Predicate CanonicalPred = getMinMaxPred(SPR.Flavor); + if (Cmp.getOperand(0) == LHS && Cmp.getOperand(1) == RHS && + Cmp.getPredicate() == CanonicalPred) + return nullptr; - // Create the canonical compare and plug it into the select. - Sel.setCondition(Builder.CreateICmp(CanonicalPred, LHS, RHS)); + // Create the canonical compare and plug it into the select. + Sel.setCondition(Builder.CreateICmp(CanonicalPred, LHS, RHS)); - // If the select operands did not change, we're done. - if (Sel.getTrueValue() == LHS && Sel.getFalseValue() == RHS) - return &Sel; + // If the select operands did not change, we're done. + if (Sel.getTrueValue() == LHS && Sel.getFalseValue() == RHS) + return &Sel; - // If we are swapping the select operands, swap the metadata too. - assert(Sel.getTrueValue() == RHS && Sel.getFalseValue() == LHS && - "Unexpected results from matchSelectPattern"); - Sel.setTrueValue(LHS); - Sel.setFalseValue(RHS); - Sel.swapProfMetadata(); - return &Sel; -} + // If we are swapping the select operands, swap the metadata too. + assert(Sel.getTrueValue() == RHS && Sel.getFalseValue() == LHS && + "Unexpected results from matchSelectPattern"); + Sel.setTrueValue(LHS); + Sel.setFalseValue(RHS); + Sel.swapProfMetadata(); + return &Sel; + } -/// There are many select variants for each of ABS/NABS. -/// In matchSelectPattern(), there are different compare constants, compare -/// predicates/operands and select operands. -/// In isKnownNegation(), there are different formats of negated operands. -/// Canonicalize all these variants to 1 pattern. -/// This makes CSE more likely. -static Instruction *canonicalizeAbsNabs(SelectInst &Sel, ICmpInst &Cmp, - InstCombiner::BuilderTy &Builder) { - if (!Cmp.hasOneUse() || !isa(Cmp.getOperand(1))) - return nullptr; + /// There are many select variants for each of ABS/NABS. + /// In matchSelectPattern(), there are different compare constants, compare + /// predicates/operands and select operands. + /// In isKnownNegation(), there are different formats of negated operands. + /// Canonicalize all these variants to 1 pattern. + /// This makes CSE more likely. + static Instruction *canonicalizeAbsNabs(SelectInst & Sel, ICmpInst & Cmp, + InstCombiner::BuilderTy & Builder) { + if (!Cmp.hasOneUse() || !isa(Cmp.getOperand(1))) + return nullptr; - // Choose a sign-bit check for the compare (likely simpler for codegen). - // ABS: (X hasOneUse() || (RHS->hasNUses(2) && CmpUsesNegatedOp))) - return nullptr; + // If RHS is used by other instructions except compare and select, don't + // canonicalize it to not increase the instruction count. + if (!(RHS->hasOneUse() || (RHS->hasNUses(2) && CmpUsesNegatedOp))) + return nullptr; - // Create the canonical compare: icmp slt LHS 0. - if (!CmpCanonicalized) { - Cmp.setPredicate(ICmpInst::ICMP_SLT); - Cmp.setOperand(1, ConstantInt::getNullValue(Cmp.getOperand(0)->getType())); - if (CmpUsesNegatedOp) - Cmp.setOperand(0, LHS); - } + // Create the canonical compare: icmp slt LHS 0. + if (!CmpCanonicalized) { + Cmp.setPredicate(ICmpInst::ICMP_SLT); + Cmp.setOperand(1, + ConstantInt::getNullValue(Cmp.getOperand(0)->getType())); + if (CmpUsesNegatedOp) + Cmp.setOperand(0, LHS); + } + + // Create the canonical RHS: RHS = sub (0, LHS). + if (!RHSCanonicalized) { + assert(RHS->hasOneUse() && "RHS use number is not right"); + RHS = Builder.CreateNeg(LHS); + if (TVal == LHS) { + Sel.setFalseValue(RHS); + FVal = RHS; + } else { + Sel.setTrueValue(RHS); + TVal = RHS; + } + } - // Create the canonical RHS: RHS = sub (0, LHS). - if (!RHSCanonicalized) { - assert(RHS->hasOneUse() && "RHS use number is not right"); - RHS = Builder.CreateNeg(LHS); - if (TVal == LHS) { - Sel.setFalseValue(RHS); - FVal = RHS; + // If the select operands do not change, we're done. + if (SPF == SelectPatternFlavor::SPF_NABS) { + if (TVal == LHS) + return &Sel; + assert(FVal == LHS && "Unexpected results from matchSelectPattern"); } else { - Sel.setTrueValue(RHS); - TVal = RHS; + if (FVal == LHS) + return &Sel; + assert(TVal == LHS && "Unexpected results from matchSelectPattern"); } - } - // If the select operands do not change, we're done. - if (SPF == SelectPatternFlavor::SPF_NABS) { - if (TVal == LHS) - return &Sel; - assert(FVal == LHS && "Unexpected results from matchSelectPattern"); - } else { - if (FVal == LHS) - return &Sel; - assert(TVal == LHS && "Unexpected results from matchSelectPattern"); + // We are swapping the select operands, so swap the metadata too. + Sel.setTrueValue(FVal); + Sel.setFalseValue(TVal); + Sel.swapProfMetadata(); + return &Sel; } - // We are swapping the select operands, so swap the metadata too. - Sel.setTrueValue(FVal); - Sel.setFalseValue(TVal); - Sel.swapProfMetadata(); - return &Sel; -} - -/// Visit a SelectInst that has an ICmpInst as its first operand. -Instruction *InstCombiner::foldSelectInstWithICmp(SelectInst &SI, - ICmpInst *ICI) { - Value *TrueVal = SI.getTrueValue(); - Value *FalseVal = SI.getFalseValue(); - - if (Instruction *NewSel = canonicalizeMinMaxWithConstant(SI, *ICI, Builder)) - return NewSel; - - if (Instruction *NewAbs = canonicalizeAbsNabs(SI, *ICI, Builder)) - return NewAbs; - - bool Changed = adjustMinMax(SI, *ICI); - - if (Value *V = foldSelectICmpAnd(SI, ICI, Builder)) - return replaceInstUsesWith(SI, V); - - // NOTE: if we wanted to, this is where to detect integer MIN/MAX - ICmpInst::Predicate Pred = ICI->getPredicate(); - Value *CmpLHS = ICI->getOperand(0); - Value *CmpRHS = ICI->getOperand(1); - if (CmpRHS != CmpLHS && isa(CmpRHS)) { - if (CmpLHS == TrueVal && Pred == ICmpInst::ICMP_EQ) { - // Transform (X == C) ? X : Y -> (X == C) ? C : Y - SI.setOperand(1, CmpRHS); - Changed = true; - } else if (CmpLHS == FalseVal && Pred == ICmpInst::ICMP_NE) { - // Transform (X != C) ? Y : X -> (X != C) ? Y : C - SI.setOperand(2, CmpRHS); - Changed = true; - } - } - - // FIXME: This code is nearly duplicated in InstSimplify. Using/refactoring - // decomposeBitTestICmp() might help. - { - unsigned BitWidth = - DL.getTypeSizeInBits(TrueVal->getType()->getScalarType()); - APInt MinSignedValue = APInt::getSignedMinValue(BitWidth); - Value *X; - const APInt *Y, *C; - bool TrueWhenUnset; - bool IsBitTest = false; - if (ICmpInst::isEquality(Pred) && - match(CmpLHS, m_And(m_Value(X), m_Power2(Y))) && - match(CmpRHS, m_Zero())) { - IsBitTest = true; - TrueWhenUnset = Pred == ICmpInst::ICMP_EQ; - } else if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, m_Zero())) { - X = CmpLHS; - Y = &MinSignedValue; - IsBitTest = true; - TrueWhenUnset = false; - } else if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes())) { - X = CmpLHS; - Y = &MinSignedValue; - IsBitTest = true; - TrueWhenUnset = true; - } - if (IsBitTest) { - Value *V = nullptr; - // (X & Y) == 0 ? X : X ^ Y --> X & ~Y - if (TrueWhenUnset && TrueVal == X && - match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C) - V = Builder.CreateAnd(X, ~(*Y)); - // (X & Y) != 0 ? X ^ Y : X --> X & ~Y - else if (!TrueWhenUnset && FalseVal == X && - match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C) - V = Builder.CreateAnd(X, ~(*Y)); - // (X & Y) == 0 ? X ^ Y : X --> X | Y - else if (TrueWhenUnset && FalseVal == X && - match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C) - V = Builder.CreateOr(X, *Y); - // (X & Y) != 0 ? X : X ^ Y --> X | Y - else if (!TrueWhenUnset && TrueVal == X && - match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C) - V = Builder.CreateOr(X, *Y); - - if (V) - return replaceInstUsesWith(SI, V); - } - } - - if (Instruction *V = - foldSelectICmpAndAnd(SI.getType(), ICI, TrueVal, FalseVal, Builder)) - return V; - - if (Value *V = foldSelectICmpAndOr(ICI, TrueVal, FalseVal, Builder)) - return replaceInstUsesWith(SI, V); - - if (Value *V = foldSelectCttzCtlz(ICI, TrueVal, FalseVal, Builder)) - return replaceInstUsesWith(SI, V); - - if (Value *V = canonicalizeSaturatedSubtract(ICI, TrueVal, FalseVal, Builder)) - return replaceInstUsesWith(SI, V); - - return Changed ? &SI : nullptr; -} - -/// SI is a select whose condition is a PHI node (but the two may be in -/// different blocks). See if the true/false values (V) are live in all of the -/// predecessor blocks of the PHI. For example, cases like this can't be mapped: -/// -/// X = phi [ C1, BB1], [C2, BB2] -/// Y = add -/// Z = select X, Y, 0 -/// -/// because Y is not live in BB1/BB2. -static bool canSelectOperandBeMappingIntoPredBlock(const Value *V, - const SelectInst &SI) { - // If the value is a non-instruction value like a constant or argument, it - // can always be mapped. - const Instruction *I = dyn_cast(V); - if (!I) return true; - - // If V is a PHI node defined in the same block as the condition PHI, we can - // map the arguments. - const PHINode *CondPHI = cast(SI.getCondition()); - - if (const PHINode *VP = dyn_cast(I)) - if (VP->getParent() == CondPHI->getParent()) + /// Visit a SelectInst that has an ICmpInst as its first operand. + Instruction *InstCombiner::foldSelectInstWithICmp(SelectInst & SI, + ICmpInst * ICI) { + Value *TrueVal = SI.getTrueValue(); + Value *FalseVal = SI.getFalseValue(); + + if (Instruction *NewSel = canonicalizeMinMaxWithConstant(SI, *ICI, Builder)) + return NewSel; + + if (Instruction *NewAbs = canonicalizeAbsNabs(SI, *ICI, Builder)) + return NewAbs; + + bool Changed = adjustMinMax(SI, *ICI); + + if (Value *V = foldSelectICmpAnd(SI, ICI, Builder)) + return replaceInstUsesWith(SI, V); + + // NOTE: if we wanted to, this is where to detect integer MIN/MAX + ICmpInst::Predicate Pred = ICI->getPredicate(); + Value *CmpLHS = ICI->getOperand(0); + Value *CmpRHS = ICI->getOperand(1); + if (CmpRHS != CmpLHS && isa(CmpRHS)) { + if (CmpLHS == TrueVal && Pred == ICmpInst::ICMP_EQ) { + // Transform (X == C) ? X : Y -> (X == C) ? C : Y + SI.setOperand(1, CmpRHS); + Changed = true; + } else if (CmpLHS == FalseVal && Pred == ICmpInst::ICMP_NE) { + // Transform (X != C) ? Y : X -> (X != C) ? Y : C + SI.setOperand(2, CmpRHS); + Changed = true; + } + } + + // FIXME: This code is nearly duplicated in InstSimplify. Using/refactoring + // decomposeBitTestICmp() might help. + { + unsigned BitWidth = + DL.getTypeSizeInBits(TrueVal->getType()->getScalarType()); + APInt MinSignedValue = APInt::getSignedMinValue(BitWidth); + Value *X; + const APInt *Y, *C; + bool TrueWhenUnset; + bool IsBitTest = false; + if (ICmpInst::isEquality(Pred) && + match(CmpLHS, m_And(m_Value(X), m_Power2(Y))) && + match(CmpRHS, m_Zero())) { + IsBitTest = true; + TrueWhenUnset = Pred == ICmpInst::ICMP_EQ; + } else if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, m_Zero())) { + X = CmpLHS; + Y = &MinSignedValue; + IsBitTest = true; + TrueWhenUnset = false; + } else if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes())) { + X = CmpLHS; + Y = &MinSignedValue; + IsBitTest = true; + TrueWhenUnset = true; + } + if (IsBitTest) { + Value *V = nullptr; + // (X & Y) == 0 ? X : X ^ Y --> X & ~Y + if (TrueWhenUnset && TrueVal == X && + match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C) + V = Builder.CreateAnd(X, ~(*Y)); + // (X & Y) != 0 ? X ^ Y : X --> X & ~Y + else if (!TrueWhenUnset && FalseVal == X && + match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C) + V = Builder.CreateAnd(X, ~(*Y)); + // (X & Y) == 0 ? X ^ Y : X --> X | Y + else if (TrueWhenUnset && FalseVal == X && + match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C) + V = Builder.CreateOr(X, *Y); + // (X & Y) != 0 ? X : X ^ Y --> X | Y + else if (!TrueWhenUnset && TrueVal == X && + match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C) + V = Builder.CreateOr(X, *Y); + + if (V) + return replaceInstUsesWith(SI, V); + } + } + + if (Instruction *V = + foldSelectICmpAndAnd(SI.getType(), ICI, TrueVal, FalseVal, Builder)) + return V; + + if (Value *V = foldSelectICmpAndOr(ICI, TrueVal, FalseVal, Builder)) + return replaceInstUsesWith(SI, V); + + if (Value *V = foldSelectCttzCtlz(ICI, TrueVal, FalseVal, Builder)) + return replaceInstUsesWith(SI, V); + + if (Value *V = + canonicalizeSaturatedSubtract(ICI, TrueVal, FalseVal, Builder)) + return replaceInstUsesWith(SI, V); + + return Changed ? &SI : nullptr; + } + + /// SI is a select whose condition is a PHI node (but the two may be in + /// different blocks). See if the true/false values (V) are live in all of the + /// predecessor blocks of the PHI. For example, cases like this can't be + /// mapped: + /// + /// X = phi [ C1, BB1], [C2, BB2] + /// Y = add + /// Z = select X, Y, 0 + /// + /// because Y is not live in BB1/BB2. + static bool canSelectOperandBeMappingIntoPredBlock(const Value *V, + const SelectInst &SI) { + // If the value is a non-instruction value like a constant or argument, it + // can always be mapped. + const Instruction *I = dyn_cast(V); + if (!I) return true; - // Otherwise, if the PHI and select are defined in the same block and if V is - // defined in a different block, then we can transform it. - if (SI.getParent() == CondPHI->getParent() && - I->getParent() != CondPHI->getParent()) - return true; - - // Otherwise we have a 'hard' case and we can't tell without doing more - // detailed dominator based analysis, punt. - return false; -} + // If V is a PHI node defined in the same block as the condition PHI, we can + // map the arguments. + const PHINode *CondPHI = cast(SI.getCondition()); + + if (const PHINode *VP = dyn_cast(I)) + if (VP->getParent() == CondPHI->getParent()) + return true; + + // Otherwise, if the PHI and select are defined in the same block and if V + // is + // defined in a different block, then we can transform it. + if (SI.getParent() == CondPHI->getParent() && + I->getParent() != CondPHI->getParent()) + return true; -/// We have an SPF (e.g. a min or max) of an SPF of the form: -/// SPF2(SPF1(A, B), C) -Instruction *InstCombiner::foldSPFofSPF(Instruction *Inner, - SelectPatternFlavor SPF1, - Value *A, Value *B, - Instruction &Outer, - SelectPatternFlavor SPF2, Value *C) { - if (Outer.getType() != Inner->getType()) - return nullptr; + // Otherwise we have a 'hard' case and we can't tell without doing more + // detailed dominator based analysis, punt. + return false; + } - if (C == A || C == B) { - // MAX(MAX(A, B), B) -> MAX(A, B) - // MIN(MIN(a, b), a) -> MIN(a, b) - if (SPF1 == SPF2 && SelectPatternResult::isMinOrMax(SPF1)) - return replaceInstUsesWith(Outer, Inner); + /// We have an SPF (e.g. a min or max) of an SPF of the form: + /// SPF2(SPF1(A, B), C) + Instruction *InstCombiner::foldSPFofSPF( + Instruction * Inner, SelectPatternFlavor SPF1, Value * A, Value * B, + Instruction & Outer, SelectPatternFlavor SPF2, Value * C) { + if (Outer.getType() != Inner->getType()) + return nullptr; - // MAX(MIN(a, b), a) -> a - // MIN(MAX(a, b), a) -> a - if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) || - (SPF1 == SPF_SMAX && SPF2 == SPF_SMIN) || - (SPF1 == SPF_UMIN && SPF2 == SPF_UMAX) || - (SPF1 == SPF_UMAX && SPF2 == SPF_UMIN)) - return replaceInstUsesWith(Outer, C); - } - - if (SPF1 == SPF2) { - const APInt *CB, *CC; - if (match(B, m_APInt(CB)) && match(C, m_APInt(CC))) { - // MIN(MIN(A, 23), 97) -> MIN(A, 23) - // MAX(MAX(A, 97), 23) -> MAX(A, 97) - if ((SPF1 == SPF_UMIN && CB->ule(*CC)) || - (SPF1 == SPF_SMIN && CB->sle(*CC)) || - (SPF1 == SPF_UMAX && CB->uge(*CC)) || - (SPF1 == SPF_SMAX && CB->sge(*CC))) + if (C == A || C == B) { + // MAX(MAX(A, B), B) -> MAX(A, B) + // MIN(MIN(a, b), a) -> MIN(a, b) + if (SPF1 == SPF2 && SelectPatternResult::isMinOrMax(SPF1)) return replaceInstUsesWith(Outer, Inner); - // MIN(MIN(A, 97), 23) -> MIN(A, 23) - // MAX(MAX(A, 23), 97) -> MAX(A, 97) - if ((SPF1 == SPF_UMIN && CB->ugt(*CC)) || - (SPF1 == SPF_SMIN && CB->sgt(*CC)) || - (SPF1 == SPF_UMAX && CB->ult(*CC)) || - (SPF1 == SPF_SMAX && CB->slt(*CC))) { - Outer.replaceUsesOfWith(Inner, A); - return &Outer; + // MAX(MIN(a, b), a) -> a + // MIN(MAX(a, b), a) -> a + if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) || + (SPF1 == SPF_SMAX && SPF2 == SPF_SMIN) || + (SPF1 == SPF_UMIN && SPF2 == SPF_UMAX) || + (SPF1 == SPF_UMAX && SPF2 == SPF_UMIN)) + return replaceInstUsesWith(Outer, C); + } + + if (SPF1 == SPF2) { + const APInt *CB, *CC; + if (match(B, m_APInt(CB)) && match(C, m_APInt(CC))) { + // MIN(MIN(A, 23), 97) -> MIN(A, 23) + // MAX(MAX(A, 97), 23) -> MAX(A, 97) + if ((SPF1 == SPF_UMIN && CB->ule(*CC)) || + (SPF1 == SPF_SMIN && CB->sle(*CC)) || + (SPF1 == SPF_UMAX && CB->uge(*CC)) || + (SPF1 == SPF_SMAX && CB->sge(*CC))) + return replaceInstUsesWith(Outer, Inner); + + // MIN(MIN(A, 97), 23) -> MIN(A, 23) + // MAX(MAX(A, 23), 97) -> MAX(A, 97) + if ((SPF1 == SPF_UMIN && CB->ugt(*CC)) || + (SPF1 == SPF_SMIN && CB->sgt(*CC)) || + (SPF1 == SPF_UMAX && CB->ult(*CC)) || + (SPF1 == SPF_SMAX && CB->slt(*CC))) { + Outer.replaceUsesOfWith(Inner, A); + return &Outer; + } } } - } - // ABS(ABS(X)) -> ABS(X) - // NABS(NABS(X)) -> NABS(X) - if (SPF1 == SPF2 && (SPF1 == SPF_ABS || SPF1 == SPF_NABS)) { - return replaceInstUsesWith(Outer, Inner); - } - - // ABS(NABS(X)) -> ABS(X) - // NABS(ABS(X)) -> NABS(X) - if ((SPF1 == SPF_ABS && SPF2 == SPF_NABS) || - (SPF1 == SPF_NABS && SPF2 == SPF_ABS)) { - SelectInst *SI = cast(Inner); - Value *NewSI = - Builder.CreateSelect(SI->getCondition(), SI->getFalseValue(), - SI->getTrueValue(), SI->getName(), SI); - return replaceInstUsesWith(Outer, NewSI); - } - - auto IsFreeOrProfitableToInvert = - [&](Value *V, Value *&NotV, bool &ElidesXor) { - if (match(V, m_Not(m_Value(NotV)))) { - // If V has at most 2 uses then we can get rid of the xor operation - // entirely. - ElidesXor |= !V->hasNUsesOrMore(3); - return true; + // ABS(ABS(X)) -> ABS(X) + // NABS(NABS(X)) -> NABS(X) + if (SPF1 == SPF2 && (SPF1 == SPF_ABS || SPF1 == SPF_NABS)) { + return replaceInstUsesWith(Outer, Inner); } - if (IsFreeToInvert(V, !V->hasNUsesOrMore(3))) { - NotV = nullptr; - return true; - } + // ABS(NABS(X)) -> ABS(X) + // NABS(ABS(X)) -> NABS(X) + if ((SPF1 == SPF_ABS && SPF2 == SPF_NABS) || + (SPF1 == SPF_NABS && SPF2 == SPF_ABS)) { + SelectInst *SI = cast(Inner); + Value *NewSI = + Builder.CreateSelect(SI->getCondition(), SI->getFalseValue(), + SI->getTrueValue(), SI->getName(), SI); + return replaceInstUsesWith(Outer, NewSI); + } + + auto IsFreeOrProfitableToInvert = [&](Value *V, Value *&NotV, + bool &ElidesXor) { + if (match(V, m_Not(m_Value(NotV)))) { + // If V has at most 2 uses then we can get rid of the xor operation + // entirely. + ElidesXor |= !V->hasNUsesOrMore(3); + return true; + } + + if (IsFreeToInvert(V, !V->hasNUsesOrMore(3))) { + NotV = nullptr; + return true; + } - return false; - }; + return false; + }; + + Value *NotA, *NotB, *NotC; + bool ElidesXor = false; - Value *NotA, *NotB, *NotC; - bool ElidesXor = false; + // MIN(MIN(~A, ~B), ~C) == ~MAX(MAX(A, B), C) + // MIN(MAX(~A, ~B), ~C) == ~MAX(MIN(A, B), C) + // MAX(MIN(~A, ~B), ~C) == ~MIN(MAX(A, B), C) + // MAX(MAX(~A, ~B), ~C) == ~MIN(MIN(A, B), C) + // + // This transform is performance neutral if we can elide at least one xor + // from + // the set of three operands, since we'll be tacking on an xor at the very + // end. + if (SelectPatternResult::isMinOrMax(SPF1) && + SelectPatternResult::isMinOrMax(SPF2) && + IsFreeOrProfitableToInvert(A, NotA, ElidesXor) && + IsFreeOrProfitableToInvert(B, NotB, ElidesXor) && + IsFreeOrProfitableToInvert(C, NotC, ElidesXor) && ElidesXor) { + if (!NotA) + NotA = Builder.CreateNot(A); + if (!NotB) + NotB = Builder.CreateNot(B); + if (!NotC) + NotC = Builder.CreateNot(C); + + Value *NewInner = + createMinMax(Builder, getInverseMinMaxFlavor(SPF1), NotA, NotB); + Value *NewOuter = Builder.CreateNot( + createMinMax(Builder, getInverseMinMaxFlavor(SPF2), NewInner, NotC)); + return replaceInstUsesWith(Outer, NewOuter); + } - // MIN(MIN(~A, ~B), ~C) == ~MAX(MAX(A, B), C) - // MIN(MAX(~A, ~B), ~C) == ~MAX(MIN(A, B), C) - // MAX(MIN(~A, ~B), ~C) == ~MIN(MAX(A, B), C) - // MAX(MAX(~A, ~B), ~C) == ~MIN(MIN(A, B), C) - // - // This transform is performance neutral if we can elide at least one xor from - // the set of three operands, since we'll be tacking on an xor at the very - // end. - if (SelectPatternResult::isMinOrMax(SPF1) && - SelectPatternResult::isMinOrMax(SPF2) && - IsFreeOrProfitableToInvert(A, NotA, ElidesXor) && - IsFreeOrProfitableToInvert(B, NotB, ElidesXor) && - IsFreeOrProfitableToInvert(C, NotC, ElidesXor) && ElidesXor) { - if (!NotA) - NotA = Builder.CreateNot(A); - if (!NotB) - NotB = Builder.CreateNot(B); - if (!NotC) - NotC = Builder.CreateNot(C); - - Value *NewInner = createMinMax(Builder, getInverseMinMaxFlavor(SPF1), NotA, - NotB); - Value *NewOuter = Builder.CreateNot( - createMinMax(Builder, getInverseMinMaxFlavor(SPF2), NewInner, NotC)); - return replaceInstUsesWith(Outer, NewOuter); + return nullptr; } - return nullptr; -} + /// Turn select C, (X + Y), (X - Y) --> (X + (select C, Y, (-Y))). + /// This is even legal for FP. + static Instruction *foldAddSubSelect(SelectInst & SI, + InstCombiner::BuilderTy & Builder) { + Value *CondVal = SI.getCondition(); + Value *TrueVal = SI.getTrueValue(); + Value *FalseVal = SI.getFalseValue(); + auto *TI = dyn_cast(TrueVal); + auto *FI = dyn_cast(FalseVal); + if (!TI || !FI || !TI->hasOneUse() || !FI->hasOneUse()) + return nullptr; -/// Turn select C, (X + Y), (X - Y) --> (X + (select C, Y, (-Y))). -/// This is even legal for FP. -static Instruction *foldAddSubSelect(SelectInst &SI, - InstCombiner::BuilderTy &Builder) { - Value *CondVal = SI.getCondition(); - Value *TrueVal = SI.getTrueValue(); - Value *FalseVal = SI.getFalseValue(); - auto *TI = dyn_cast(TrueVal); - auto *FI = dyn_cast(FalseVal); - if (!TI || !FI || !TI->hasOneUse() || !FI->hasOneUse()) - return nullptr; + Instruction *AddOp = nullptr, *SubOp = nullptr; + if ((TI->getOpcode() == Instruction::Sub && + FI->getOpcode() == Instruction::Add) || + (TI->getOpcode() == Instruction::FSub && + FI->getOpcode() == Instruction::FAdd)) { + AddOp = FI; + SubOp = TI; + } else if ((FI->getOpcode() == Instruction::Sub && + TI->getOpcode() == Instruction::Add) || + (FI->getOpcode() == Instruction::FSub && + TI->getOpcode() == Instruction::FAdd)) { + AddOp = TI; + SubOp = FI; + } + + if (AddOp) { + Value *OtherAddOp = nullptr; + if (SubOp->getOperand(0) == AddOp->getOperand(0)) { + OtherAddOp = AddOp->getOperand(1); + } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) { + OtherAddOp = AddOp->getOperand(0); + } + + if (OtherAddOp) { + // So at this point we know we have (Y -> OtherAddOp): + // select C, (add X, Y), (sub X, Z) + Value *NegVal; // Compute -Z + if (SI.getType()->isFPOrFPVectorTy()) { + NegVal = Builder.CreateFNeg(SubOp->getOperand(1)); + if (Instruction *NegInst = dyn_cast(NegVal)) { + FastMathFlags Flags = AddOp->getFastMathFlags(); + Flags &= SubOp->getFastMathFlags(); + NegInst->setFastMathFlags(Flags); + } + } else { + NegVal = Builder.CreateNeg(SubOp->getOperand(1)); + } + + Value *NewTrueOp = OtherAddOp; + Value *NewFalseOp = NegVal; + if (AddOp != TI) + std::swap(NewTrueOp, NewFalseOp); + Value *NewSel = Builder.CreateSelect(CondVal, NewTrueOp, NewFalseOp, + SI.getName() + ".p", &SI); + + if (SI.getType()->isFPOrFPVectorTy()) { + Instruction *RI = + BinaryOperator::CreateFAdd(SubOp->getOperand(0), NewSel); - Instruction *AddOp = nullptr, *SubOp = nullptr; - if ((TI->getOpcode() == Instruction::Sub && - FI->getOpcode() == Instruction::Add) || - (TI->getOpcode() == Instruction::FSub && - FI->getOpcode() == Instruction::FAdd)) { - AddOp = FI; - SubOp = TI; - } else if ((FI->getOpcode() == Instruction::Sub && - TI->getOpcode() == Instruction::Add) || - (FI->getOpcode() == Instruction::FSub && - TI->getOpcode() == Instruction::FAdd)) { - AddOp = TI; - SubOp = FI; - } - - if (AddOp) { - Value *OtherAddOp = nullptr; - if (SubOp->getOperand(0) == AddOp->getOperand(0)) { - OtherAddOp = AddOp->getOperand(1); - } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) { - OtherAddOp = AddOp->getOperand(0); - } - - if (OtherAddOp) { - // So at this point we know we have (Y -> OtherAddOp): - // select C, (add X, Y), (sub X, Z) - Value *NegVal; // Compute -Z - if (SI.getType()->isFPOrFPVectorTy()) { - NegVal = Builder.CreateFNeg(SubOp->getOperand(1)); - if (Instruction *NegInst = dyn_cast(NegVal)) { FastMathFlags Flags = AddOp->getFastMathFlags(); Flags &= SubOp->getFastMathFlags(); - NegInst->setFastMathFlags(Flags); - } - } else { - NegVal = Builder.CreateNeg(SubOp->getOperand(1)); + RI->setFastMathFlags(Flags); + return RI; + } else + return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel); } - - Value *NewTrueOp = OtherAddOp; - Value *NewFalseOp = NegVal; - if (AddOp != TI) - std::swap(NewTrueOp, NewFalseOp); - Value *NewSel = Builder.CreateSelect(CondVal, NewTrueOp, NewFalseOp, - SI.getName() + ".p", &SI); - - if (SI.getType()->isFPOrFPVectorTy()) { - Instruction *RI = - BinaryOperator::CreateFAdd(SubOp->getOperand(0), NewSel); - - FastMathFlags Flags = AddOp->getFastMathFlags(); - Flags &= SubOp->getFastMathFlags(); - RI->setFastMathFlags(Flags); - return RI; - } else - return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel); } + return nullptr; } - return nullptr; -} -Instruction *InstCombiner::foldSelectExtConst(SelectInst &Sel) { - Constant *C; - if (!match(Sel.getTrueValue(), m_Constant(C)) && - !match(Sel.getFalseValue(), m_Constant(C))) - return nullptr; + Instruction *InstCombiner::foldSelectExtConst(SelectInst & Sel) { + Constant *C; + if (!match(Sel.getTrueValue(), m_Constant(C)) && + !match(Sel.getFalseValue(), m_Constant(C))) + return nullptr; - Instruction *ExtInst; - if (!match(Sel.getTrueValue(), m_Instruction(ExtInst)) && - !match(Sel.getFalseValue(), m_Instruction(ExtInst))) - return nullptr; + Instruction *ExtInst; + if (!match(Sel.getTrueValue(), m_Instruction(ExtInst)) && + !match(Sel.getFalseValue(), m_Instruction(ExtInst))) + return nullptr; - auto ExtOpcode = ExtInst->getOpcode(); - if (ExtOpcode != Instruction::ZExt && ExtOpcode != Instruction::SExt) - return nullptr; + auto ExtOpcode = ExtInst->getOpcode(); + if (ExtOpcode != Instruction::ZExt && ExtOpcode != Instruction::SExt) + return nullptr; + + // If we are extending from a boolean type or if we can create a select that + // has the same size operands as its condition, try to narrow the select. + Value *X = ExtInst->getOperand(0); + Type *SmallType = X->getType(); + Value *Cond = Sel.getCondition(); + auto *Cmp = dyn_cast(Cond); + if (!SmallType->isIntOrIntVectorTy(1) && + (!Cmp || Cmp->getOperand(0)->getType() != SmallType)) + return nullptr; + + // If the constant is the same after truncation to the smaller type and + // extension to the original type, we can narrow the select. + Type *SelType = Sel.getType(); + Constant *TruncC = ConstantExpr::getTrunc(C, SmallType); + Constant *ExtC = ConstantExpr::getCast(ExtOpcode, TruncC, SelType); + if (ExtC == C) { + Value *TruncCVal = cast(TruncC); + if (ExtInst == Sel.getFalseValue()) + std::swap(X, TruncCVal); + + // select Cond, (ext X), C --> ext(select Cond, X, C') + // select Cond, C, (ext X) --> ext(select Cond, C', X) + Value *NewSel = Builder.CreateSelect(Cond, X, TruncCVal, "narrow", &Sel); + return CastInst::Create(Instruction::CastOps(ExtOpcode), NewSel, SelType); + } + + // If one arm of the select is the extend of the condition, replace that arm + // with the extension of the appropriate known bool value. + if (Cond == X) { + if (ExtInst == Sel.getTrueValue()) { + // select X, (sext X), C --> select X, -1, C + // select X, (zext X), C --> select X, 1, C + Constant *One = ConstantInt::getTrue(SmallType); + Constant *AllOnesOrOne = ConstantExpr::getCast(ExtOpcode, One, SelType); + return SelectInst::Create(Cond, AllOnesOrOne, C, "", nullptr, &Sel); + } else { + // select X, C, (sext X) --> select X, C, 0 + // select X, C, (zext X) --> select X, C, 0 + Constant *Zero = ConstantInt::getNullValue(SelType); + return SelectInst::Create(Cond, C, Zero, "", nullptr, &Sel); + } + } - // If we are extending from a boolean type or if we can create a select that - // has the same size operands as its condition, try to narrow the select. - Value *X = ExtInst->getOperand(0); - Type *SmallType = X->getType(); - Value *Cond = Sel.getCondition(); - auto *Cmp = dyn_cast(Cond); - if (!SmallType->isIntOrIntVectorTy(1) && - (!Cmp || Cmp->getOperand(0)->getType() != SmallType)) return nullptr; + } - // If the constant is the same after truncation to the smaller type and - // extension to the original type, we can narrow the select. - Type *SelType = Sel.getType(); - Constant *TruncC = ConstantExpr::getTrunc(C, SmallType); - Constant *ExtC = ConstantExpr::getCast(ExtOpcode, TruncC, SelType); - if (ExtC == C) { - Value *TruncCVal = cast(TruncC); - if (ExtInst == Sel.getFalseValue()) - std::swap(X, TruncCVal); - - // select Cond, (ext X), C --> ext(select Cond, X, C') - // select Cond, C, (ext X) --> ext(select Cond, C', X) - Value *NewSel = Builder.CreateSelect(Cond, X, TruncCVal, "narrow", &Sel); - return CastInst::Create(Instruction::CastOps(ExtOpcode), NewSel, SelType); - } - - // If one arm of the select is the extend of the condition, replace that arm - // with the extension of the appropriate known bool value. - if (Cond == X) { - if (ExtInst == Sel.getTrueValue()) { - // select X, (sext X), C --> select X, -1, C - // select X, (zext X), C --> select X, 1, C - Constant *One = ConstantInt::getTrue(SmallType); - Constant *AllOnesOrOne = ConstantExpr::getCast(ExtOpcode, One, SelType); - return SelectInst::Create(Cond, AllOnesOrOne, C, "", nullptr, &Sel); - } else { - // select X, C, (sext X) --> select X, C, 0 - // select X, C, (zext X) --> select X, C, 0 - Constant *Zero = ConstantInt::getNullValue(SelType); - return SelectInst::Create(Cond, C, Zero, "", nullptr, &Sel); + /// Try to transform a vector select with a constant condition vector into a + /// shuffle for easier combining with other shuffles and insert/extract. + static Instruction *canonicalizeSelectToShuffle(SelectInst & SI) { + Value *CondVal = SI.getCondition(); + Constant *CondC; + if (!CondVal->getType()->isVectorTy() || !match(CondVal, m_Constant(CondC))) + return nullptr; + + unsigned NumElts = CondVal->getType()->getVectorNumElements(); + SmallVector Mask; + Mask.reserve(NumElts); + Type *Int32Ty = Type::getInt32Ty(CondVal->getContext()); + for (unsigned i = 0; i != NumElts; ++i) { + Constant *Elt = CondC->getAggregateElement(i); + if (!Elt) + return nullptr; + + if (Elt->isOneValue()) { + // If the select condition element is true, choose from the 1st vector. + Mask.push_back(ConstantInt::get(Int32Ty, i)); + } else if (Elt->isNullValue()) { + // If the select condition element is false, choose from the 2nd vector. + Mask.push_back(ConstantInt::get(Int32Ty, i + NumElts)); + } else if (isa(Elt)) { + // Undef in a select condition (choose one of the operands) does not + // mean + // the same thing as undef in a shuffle mask (any value is acceptable), + // so + // give up. + return nullptr; + } else { + // Bail out on a constant expression. + return nullptr; + } } + + return new ShuffleVectorInst(SI.getTrueValue(), SI.getFalseValue(), + ConstantVector::get(Mask)); } - return nullptr; -} + /// Reuse bitcasted operands between a compare and select: + /// select (cmp (bitcast C), (bitcast D)), (bitcast' C), (bitcast' D) --> + /// bitcast (select (cmp (bitcast C), (bitcast D)), (bitcast C), (bitcast D)) + static Instruction *foldSelectCmpBitcasts(SelectInst & Sel, + InstCombiner::BuilderTy & Builder) { + Value *Cond = Sel.getCondition(); + Value *TVal = Sel.getTrueValue(); + Value *FVal = Sel.getFalseValue(); + + CmpInst::Predicate Pred; + Value *A, *B; + if (!match(Cond, m_Cmp(Pred, m_Value(A), m_Value(B)))) + return nullptr; -/// Try to transform a vector select with a constant condition vector into a -/// shuffle for easier combining with other shuffles and insert/extract. -static Instruction *canonicalizeSelectToShuffle(SelectInst &SI) { - Value *CondVal = SI.getCondition(); - Constant *CondC; - if (!CondVal->getType()->isVectorTy() || !match(CondVal, m_Constant(CondC))) - return nullptr; + // The select condition is a compare instruction. If the select's true/false + // values are already the same as the compare operands, there's nothing to + // do. + if (TVal == A || TVal == B || FVal == A || FVal == B) + return nullptr; + + Value *C, *D; + if (!match(A, m_BitCast(m_Value(C))) || !match(B, m_BitCast(m_Value(D)))) + return nullptr; - unsigned NumElts = CondVal->getType()->getVectorNumElements(); - SmallVector Mask; - Mask.reserve(NumElts); - Type *Int32Ty = Type::getInt32Ty(CondVal->getContext()); - for (unsigned i = 0; i != NumElts; ++i) { - Constant *Elt = CondC->getAggregateElement(i); - if (!Elt) - return nullptr; - - if (Elt->isOneValue()) { - // If the select condition element is true, choose from the 1st vector. - Mask.push_back(ConstantInt::get(Int32Ty, i)); - } else if (Elt->isNullValue()) { - // If the select condition element is false, choose from the 2nd vector. - Mask.push_back(ConstantInt::get(Int32Ty, i + NumElts)); - } else if (isa(Elt)) { - // Undef in a select condition (choose one of the operands) does not mean - // the same thing as undef in a shuffle mask (any value is acceptable), so - // give up. + // select (cmp (bitcast C), (bitcast D)), (bitcast TSrc), (bitcast FSrc) + Value *TSrc, *FSrc; + if (!match(TVal, m_BitCast(m_Value(TSrc))) || + !match(FVal, m_BitCast(m_Value(FSrc)))) return nullptr; + + // If the select true/false values are *different bitcasts* of the same + // source + // operands, make the select operands the same as the compare operands and + // cast the result. This is the canonical select form for min/max. + Value *NewSel; + if (TSrc == C && FSrc == D) { + // select (cmp (bitcast C), (bitcast D)), (bitcast' C), (bitcast' D) --> + // bitcast (select (cmp A, B), A, B) + NewSel = Builder.CreateSelect(Cond, A, B, "", &Sel); + } else if (TSrc == D && FSrc == C) { + // select (cmp (bitcast C), (bitcast D)), (bitcast' D), (bitcast' C) --> + // bitcast (select (cmp A, B), B, A) + NewSel = Builder.CreateSelect(Cond, B, A, "", &Sel); } else { - // Bail out on a constant expression. return nullptr; } + return CastInst::CreateBitOrPointerCast(NewSel, Sel.getType()); } - return new ShuffleVectorInst(SI.getTrueValue(), SI.getFalseValue(), - ConstantVector::get(Mask)); -} - -/// Reuse bitcasted operands between a compare and select: -/// select (cmp (bitcast C), (bitcast D)), (bitcast' C), (bitcast' D) --> -/// bitcast (select (cmp (bitcast C), (bitcast D)), (bitcast C), (bitcast D)) -static Instruction *foldSelectCmpBitcasts(SelectInst &Sel, - InstCombiner::BuilderTy &Builder) { - Value *Cond = Sel.getCondition(); - Value *TVal = Sel.getTrueValue(); - Value *FVal = Sel.getFalseValue(); - - CmpInst::Predicate Pred; - Value *A, *B; - if (!match(Cond, m_Cmp(Pred, m_Value(A), m_Value(B)))) - return nullptr; + /// Try to eliminate select instructions that test the returned flag of + /// cmpxchg + /// instructions. + /// + /// If a select instruction tests the returned flag of a cmpxchg instruction + /// and + /// selects between the returned value of the cmpxchg instruction its compare + /// operand, the result of the select will always be equal to its false value. + /// For example: + /// + /// %0 = cmpxchg i64* %ptr, i64 %compare, i64 %new_value seq_cst seq_cst + /// %1 = extractvalue { i64, i1 } %0, 1 + /// %2 = extractvalue { i64, i1 } %0, 0 + /// %3 = select i1 %1, i64 %compare, i64 %2 + /// ret i64 %3 + /// + /// The returned value of the cmpxchg instruction (%2) is the original value + /// located at %ptr prior to any update. If the cmpxchg operation succeeds, %2 + /// must have been equal to %compare. Thus, the result of the select is always + /// equal to %2, and the code can be simplified to: + /// + /// %0 = cmpxchg i64* %ptr, i64 %compare, i64 %new_value seq_cst seq_cst + /// %1 = extractvalue { i64, i1 } %0, 0 + /// ret i64 %1 + /// + static Instruction *foldSelectCmpXchg(SelectInst & SI) { + // A helper that determines if V is an extractvalue instruction whose + // aggregate operand is a cmpxchg instruction and whose single index is + // equal + // to I. If such conditions are true, the helper returns the cmpxchg + // instruction; otherwise, a nullptr is returned. + auto isExtractFromCmpXchg = [](Value *V, + unsigned I) -> AtomicCmpXchgInst * { + auto *Extract = dyn_cast(V); + if (!Extract) + return nullptr; + if (Extract->getIndices()[0] != I) + return nullptr; + return dyn_cast(Extract->getAggregateOperand()); + }; - // The select condition is a compare instruction. If the select's true/false - // values are already the same as the compare operands, there's nothing to do. - if (TVal == A || TVal == B || FVal == A || FVal == B) - return nullptr; + // If the select has a single user, and this user is a select instruction + // that + // we can simplify, skip the cmpxchg simplification for now. + if (SI.hasOneUse()) + if (auto *Select = dyn_cast(SI.user_back())) + if (Select->getCondition() == SI.getCondition()) + if (Select->getFalseValue() == SI.getTrueValue() || + Select->getTrueValue() == SI.getFalseValue()) + return nullptr; + + // Ensure the select condition is the returned flag of a cmpxchg + // instruction. + auto *CmpXchg = isExtractFromCmpXchg(SI.getCondition(), 1); + if (!CmpXchg) + return nullptr; - Value *C, *D; - if (!match(A, m_BitCast(m_Value(C))) || !match(B, m_BitCast(m_Value(D)))) - return nullptr; + // Check the true value case: The true value of the select is the returned + // value of the same cmpxchg used by the condition, and the false value is + // the + // cmpxchg instruction's compare operand. + if (auto *X = isExtractFromCmpXchg(SI.getTrueValue(), 0)) + if (X == CmpXchg && X->getCompareOperand() == SI.getFalseValue()) { + SI.setTrueValue(SI.getFalseValue()); + return &SI; + } - // select (cmp (bitcast C), (bitcast D)), (bitcast TSrc), (bitcast FSrc) - Value *TSrc, *FSrc; - if (!match(TVal, m_BitCast(m_Value(TSrc))) || - !match(FVal, m_BitCast(m_Value(FSrc)))) - return nullptr; + // Check the false value case: The false value of the select is the returned + // value of the same cmpxchg used by the condition, and the true value is + // the + // cmpxchg instruction's compare operand. + if (auto *X = isExtractFromCmpXchg(SI.getFalseValue(), 0)) + if (X == CmpXchg && X->getCompareOperand() == SI.getTrueValue()) { + SI.setTrueValue(SI.getFalseValue()); + return &SI; + } - // If the select true/false values are *different bitcasts* of the same source - // operands, make the select operands the same as the compare operands and - // cast the result. This is the canonical select form for min/max. - Value *NewSel; - if (TSrc == C && FSrc == D) { - // select (cmp (bitcast C), (bitcast D)), (bitcast' C), (bitcast' D) --> - // bitcast (select (cmp A, B), A, B) - NewSel = Builder.CreateSelect(Cond, A, B, "", &Sel); - } else if (TSrc == D && FSrc == C) { - // select (cmp (bitcast C), (bitcast D)), (bitcast' D), (bitcast' C) --> - // bitcast (select (cmp A, B), B, A) - NewSel = Builder.CreateSelect(Cond, B, A, "", &Sel); - } else { return nullptr; } - return CastInst::CreateBitOrPointerCast(NewSel, Sel.getType()); -} -/// Try to eliminate select instructions that test the returned flag of cmpxchg -/// instructions. -/// -/// If a select instruction tests the returned flag of a cmpxchg instruction and -/// selects between the returned value of the cmpxchg instruction its compare -/// operand, the result of the select will always be equal to its false value. -/// For example: -/// -/// %0 = cmpxchg i64* %ptr, i64 %compare, i64 %new_value seq_cst seq_cst -/// %1 = extractvalue { i64, i1 } %0, 1 -/// %2 = extractvalue { i64, i1 } %0, 0 -/// %3 = select i1 %1, i64 %compare, i64 %2 -/// ret i64 %3 -/// -/// The returned value of the cmpxchg instruction (%2) is the original value -/// located at %ptr prior to any update. If the cmpxchg operation succeeds, %2 -/// must have been equal to %compare. Thus, the result of the select is always -/// equal to %2, and the code can be simplified to: -/// -/// %0 = cmpxchg i64* %ptr, i64 %compare, i64 %new_value seq_cst seq_cst -/// %1 = extractvalue { i64, i1 } %0, 0 -/// ret i64 %1 -/// -static Instruction *foldSelectCmpXchg(SelectInst &SI) { - // A helper that determines if V is an extractvalue instruction whose - // aggregate operand is a cmpxchg instruction and whose single index is equal - // to I. If such conditions are true, the helper returns the cmpxchg - // instruction; otherwise, a nullptr is returned. - auto isExtractFromCmpXchg = [](Value *V, unsigned I) -> AtomicCmpXchgInst * { - auto *Extract = dyn_cast(V); - if (!Extract) - return nullptr; - if (Extract->getIndices()[0] != I) - return nullptr; - return dyn_cast(Extract->getAggregateOperand()); - }; - - // If the select has a single user, and this user is a select instruction that - // we can simplify, skip the cmpxchg simplification for now. - if (SI.hasOneUse()) - if (auto *Select = dyn_cast(SI.user_back())) - if (Select->getCondition() == SI.getCondition()) - if (Select->getFalseValue() == SI.getTrueValue() || - Select->getTrueValue() == SI.getFalseValue()) - return nullptr; + /// Reduce a sequence of min/max with a common operand. + static Instruction *factorizeMinMaxTree(SelectPatternFlavor SPF, Value * LHS, + Value * RHS, + InstCombiner::BuilderTy & Builder) { + assert(SelectPatternResult::isMinOrMax(SPF) && "Expected a min/max"); + // TODO: Allow FP min/max with nnan/nsz. + if (!LHS->getType()->isIntOrIntVectorTy()) + return nullptr; - // Ensure the select condition is the returned flag of a cmpxchg instruction. - auto *CmpXchg = isExtractFromCmpXchg(SI.getCondition(), 1); - if (!CmpXchg) - return nullptr; + // Match 3 of the same min/max ops. Example: umin(umin(), umin()). + Value *A, *B, *C, *D; + SelectPatternResult L = matchSelectPattern(LHS, A, B); + SelectPatternResult R = matchSelectPattern(RHS, C, D); + if (SPF != L.Flavor || L.Flavor != R.Flavor) + return nullptr; - // Check the true value case: The true value of the select is the returned - // value of the same cmpxchg used by the condition, and the false value is the - // cmpxchg instruction's compare operand. - if (auto *X = isExtractFromCmpXchg(SI.getTrueValue(), 0)) - if (X == CmpXchg && X->getCompareOperand() == SI.getFalseValue()) { - SI.setTrueValue(SI.getFalseValue()); - return &SI; + // Look for a common operand. The use checks are different than usual + // because + // a min/max pattern typically has 2 uses of each op: 1 by the cmp and 1 by + // the select. + Value *MinMaxOp = nullptr; + Value *ThirdOp = nullptr; + if (!LHS->hasNUsesOrMore(3) && RHS->hasNUsesOrMore(3)) { + // If the LHS is only used in this chain and the RHS is used outside of + // it, + // reuse the RHS min/max because that will eliminate the LHS. + if (D == A || C == A) { + // min(min(a, b), min(c, a)) --> min(min(c, a), b) + // min(min(a, b), min(a, d)) --> min(min(a, d), b) + MinMaxOp = RHS; + ThirdOp = B; + } else if (D == B || C == B) { + // min(min(a, b), min(c, b)) --> min(min(c, b), a) + // min(min(a, b), min(b, d)) --> min(min(b, d), a) + MinMaxOp = RHS; + ThirdOp = A; + } + } else if (!RHS->hasNUsesOrMore(3)) { + // Reuse the LHS. This will eliminate the RHS. + if (D == A || D == B) { + // min(min(a, b), min(c, a)) --> min(min(a, b), c) + // min(min(a, b), min(c, b)) --> min(min(a, b), c) + MinMaxOp = LHS; + ThirdOp = C; + } else if (C == A || C == B) { + // min(min(a, b), min(b, d)) --> min(min(a, b), d) + // min(min(a, b), min(c, b)) --> min(min(a, b), d) + MinMaxOp = LHS; + ThirdOp = D; + } } + if (!MinMaxOp || !ThirdOp) + return nullptr; - // Check the false value case: The false value of the select is the returned - // value of the same cmpxchg used by the condition, and the true value is the - // cmpxchg instruction's compare operand. - if (auto *X = isExtractFromCmpXchg(SI.getFalseValue(), 0)) - if (X == CmpXchg && X->getCompareOperand() == SI.getTrueValue()) { - SI.setTrueValue(SI.getFalseValue()); - return &SI; + CmpInst::Predicate P = getMinMaxPred(SPF); + Value *CmpABC = Builder.CreateICmp(P, MinMaxOp, ThirdOp); + return SelectInst::Create(CmpABC, MinMaxOp, ThirdOp); + } + + Instruction *InstCombiner::visitSelectInst(SelectInst & SI) { + Value *CondVal = SI.getCondition(); + Value *TrueVal = SI.getTrueValue(); + Value *FalseVal = SI.getFalseValue(); + Type *SelType = SI.getType(); + + // FIXME: Remove this workaround when freeze related patches are done. + // For select with undef operand which feeds into an equality comparison, + // don't simplify it so loop unswitch can know the equality comparison + // may have an undef operand. This is a workaround for PR31652 caused by + // descrepancy about branch on undef between LoopUnswitch and GVN. + if (isa(TrueVal) || isa(FalseVal)) { + if (llvm::any_of(SI.users(), [&](User *U) { + ICmpInst *CI = dyn_cast(U); + if (CI && CI->isEquality()) + return true; + return false; + })) { + return nullptr; + } } - return nullptr; -} - -/// Reduce a sequence of min/max with a common operand. -static Instruction *factorizeMinMaxTree(SelectPatternFlavor SPF, Value *LHS, - Value *RHS, - InstCombiner::BuilderTy &Builder) { - assert(SelectPatternResult::isMinOrMax(SPF) && "Expected a min/max"); - // TODO: Allow FP min/max with nnan/nsz. - if (!LHS->getType()->isIntOrIntVectorTy()) - return nullptr; + if (Value *V = SimplifySelectInst(CondVal, TrueVal, FalseVal, + SQ.getWithInstruction(&SI))) + return replaceInstUsesWith(SI, V); + + if (Instruction *I = canonicalizeSelectToShuffle(SI)) + return I; + + // Canonicalize a one-use integer compare with a non-canonical predicate by + // inverting the predicate and swapping the select operands. This matches a + // compare canonicalization for conditional branches. + // TODO: Should we do the same for FP compares? + CmpInst::Predicate Pred; + if (match(CondVal, m_OneUse(m_ICmp(Pred, m_Value(), m_Value()))) && + !isCanonicalPredicate(Pred)) { + // Swap true/false values and condition. + CmpInst *Cond = cast(CondVal); + Cond->setPredicate(CmpInst::getInversePredicate(Pred)); + SI.setOperand(1, FalseVal); + SI.setOperand(2, TrueVal); + SI.swapProfMetadata(); + Worklist.Add(Cond); + return &SI; + } - // Match 3 of the same min/max ops. Example: umin(umin(), umin()). - Value *A, *B, *C, *D; - SelectPatternResult L = matchSelectPattern(LHS, A, B); - SelectPatternResult R = matchSelectPattern(RHS, C, D); - if (SPF != L.Flavor || L.Flavor != R.Flavor) - return nullptr; + if (SelType->isIntOrIntVectorTy(1) && + TrueVal->getType() == CondVal->getType()) { + if (match(TrueVal, m_One())) { + // Change: A = select B, true, C --> A = or B, C + return BinaryOperator::CreateOr(CondVal, FalseVal); + } + if (match(TrueVal, m_Zero())) { + // Change: A = select B, false, C --> A = and !B, C + Value *NotCond = + Builder.CreateNot(CondVal, "not." + CondVal->getName()); + return BinaryOperator::CreateAnd(NotCond, FalseVal); + } + if (match(FalseVal, m_Zero())) { + // Change: A = select B, C, false --> A = and B, C + return BinaryOperator::CreateAnd(CondVal, TrueVal); + } + if (match(FalseVal, m_One())) { + // Change: A = select B, C, true --> A = or !B, C + Value *NotCond = + Builder.CreateNot(CondVal, "not." + CondVal->getName()); + return BinaryOperator::CreateOr(NotCond, TrueVal); + } + + // select a, a, b -> a | b + // select a, b, a -> a & b + if (CondVal == TrueVal) + return BinaryOperator::CreateOr(CondVal, FalseVal); + if (CondVal == FalseVal) + return BinaryOperator::CreateAnd(CondVal, TrueVal); + + // select a, ~a, b -> (~a) & b + // select a, b, ~a -> (~a) | b + if (match(TrueVal, m_Not(m_Specific(CondVal)))) + return BinaryOperator::CreateAnd(TrueVal, FalseVal); + if (match(FalseVal, m_Not(m_Specific(CondVal)))) + return BinaryOperator::CreateOr(TrueVal, FalseVal); + } + + // Selecting between two integer or vector splat integer constants? + // + // Note that we don't handle a scalar select of vectors: + // select i1 %c, <2 x i8> <1, 1>, <2 x i8> <0, 0> + // because that may need 3 instructions to splat the condition value: + // extend, insertelement, shufflevector. + if (SelType->isIntOrIntVectorTy() && + CondVal->getType()->isVectorTy() == SelType->isVectorTy()) { + // select C, 1, 0 -> zext C to int + if (match(TrueVal, m_One()) && match(FalseVal, m_Zero())) + return new ZExtInst(CondVal, SelType); + + // select C, -1, 0 -> sext C to int + if (match(TrueVal, m_AllOnes()) && match(FalseVal, m_Zero())) + return new SExtInst(CondVal, SelType); + + // select C, 0, 1 -> zext !C to int + if (match(TrueVal, m_Zero()) && match(FalseVal, m_One())) { + Value *NotCond = + Builder.CreateNot(CondVal, "not." + CondVal->getName()); + return new ZExtInst(NotCond, SelType); + } + + // select C, 0, -1 -> sext !C to int + if (match(TrueVal, m_Zero()) && match(FalseVal, m_AllOnes())) { + Value *NotCond = + Builder.CreateNot(CondVal, "not." + CondVal->getName()); + return new SExtInst(NotCond, SelType); + } + } + + // See if we are selecting two values based on a comparison of the two + // values. + if (FCmpInst *FCI = dyn_cast(CondVal)) { + if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) { + // Transform (X == Y) ? X : Y -> Y + if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) { + // This is not safe in general for floating point: + // consider X== -0, Y== +0. + // It becomes safe if either operand is a nonzero constant. + ConstantFP *CFPt, *CFPf; + if (((CFPt = dyn_cast(TrueVal)) && + !CFPt->getValueAPF().isZero()) || + ((CFPf = dyn_cast(FalseVal)) && + !CFPf->getValueAPF().isZero())) + return replaceInstUsesWith(SI, FalseVal); + } + // Transform (X une Y) ? X : Y -> X + if (FCI->getPredicate() == FCmpInst::FCMP_UNE) { + // This is not safe in general for floating point: + // consider X== -0, Y== +0. + // It becomes safe if either operand is a nonzero constant. + ConstantFP *CFPt, *CFPf; + if (((CFPt = dyn_cast(TrueVal)) && + !CFPt->getValueAPF().isZero()) || + ((CFPf = dyn_cast(FalseVal)) && + !CFPf->getValueAPF().isZero())) + return replaceInstUsesWith(SI, TrueVal); + } - // Look for a common operand. The use checks are different than usual because - // a min/max pattern typically has 2 uses of each op: 1 by the cmp and 1 by - // the select. - Value *MinMaxOp = nullptr; - Value *ThirdOp = nullptr; - if (!LHS->hasNUsesOrMore(3) && RHS->hasNUsesOrMore(3)) { - // If the LHS is only used in this chain and the RHS is used outside of it, - // reuse the RHS min/max because that will eliminate the LHS. - if (D == A || C == A) { - // min(min(a, b), min(c, a)) --> min(min(c, a), b) - // min(min(a, b), min(a, d)) --> min(min(a, d), b) - MinMaxOp = RHS; - ThirdOp = B; - } else if (D == B || C == B) { - // min(min(a, b), min(c, b)) --> min(min(c, b), a) - // min(min(a, b), min(b, d)) --> min(min(b, d), a) - MinMaxOp = RHS; - ThirdOp = A; - } - } else if (!RHS->hasNUsesOrMore(3)) { - // Reuse the LHS. This will eliminate the RHS. - if (D == A || D == B) { - // min(min(a, b), min(c, a)) --> min(min(a, b), c) - // min(min(a, b), min(c, b)) --> min(min(a, b), c) - MinMaxOp = LHS; - ThirdOp = C; - } else if (C == A || C == B) { - // min(min(a, b), min(b, d)) --> min(min(a, b), d) - // min(min(a, b), min(c, b)) --> min(min(a, b), d) - MinMaxOp = LHS; - ThirdOp = D; - } - } - if (!MinMaxOp || !ThirdOp) - return nullptr; + // Canonicalize to use ordered comparisons by swapping the select + // operands. + // + // e.g. + // (X ugt Y) ? X : Y -> (X ole Y) ? Y : X + if (FCI->hasOneUse() && FCmpInst::isUnordered(FCI->getPredicate())) { + FCmpInst::Predicate InvPred = FCI->getInversePredicate(); + IRBuilder<>::FastMathFlagGuard FMFG(Builder); + Builder.setFastMathFlags(FCI->getFastMathFlags()); + Value *NewCond = Builder.CreateFCmp(InvPred, TrueVal, FalseVal, + FCI->getName() + ".inv"); - CmpInst::Predicate P = getMinMaxPred(SPF); - Value *CmpABC = Builder.CreateICmp(P, MinMaxOp, ThirdOp); - return SelectInst::Create(CmpABC, MinMaxOp, ThirdOp); -} + return SelectInst::Create(NewCond, FalseVal, TrueVal, + SI.getName() + ".p"); + } -Instruction *InstCombiner::visitSelectInst(SelectInst &SI) { - Value *CondVal = SI.getCondition(); - Value *TrueVal = SI.getTrueValue(); - Value *FalseVal = SI.getFalseValue(); - Type *SelType = SI.getType(); - - // FIXME: Remove this workaround when freeze related patches are done. - // For select with undef operand which feeds into an equality comparison, - // don't simplify it so loop unswitch can know the equality comparison - // may have an undef operand. This is a workaround for PR31652 caused by - // descrepancy about branch on undef between LoopUnswitch and GVN. - if (isa(TrueVal) || isa(FalseVal)) { - if (llvm::any_of(SI.users(), [&](User *U) { - ICmpInst *CI = dyn_cast(U); - if (CI && CI->isEquality()) - return true; - return false; - })) { - return nullptr; - } - } + // NOTE: if we wanted to, this is where to detect MIN/MAX + } else if (FCI->getOperand(0) == FalseVal && + FCI->getOperand(1) == TrueVal) { + // Transform (X == Y) ? Y : X -> X + if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) { + // This is not safe in general for floating point: + // consider X== -0, Y== +0. + // It becomes safe if either operand is a nonzero constant. + ConstantFP *CFPt, *CFPf; + if (((CFPt = dyn_cast(TrueVal)) && + !CFPt->getValueAPF().isZero()) || + ((CFPf = dyn_cast(FalseVal)) && + !CFPf->getValueAPF().isZero())) + return replaceInstUsesWith(SI, FalseVal); + } + // Transform (X une Y) ? Y : X -> Y + if (FCI->getPredicate() == FCmpInst::FCMP_UNE) { + // This is not safe in general for floating point: + // consider X== -0, Y== +0. + // It becomes safe if either operand is a nonzero constant. + ConstantFP *CFPt, *CFPf; + if (((CFPt = dyn_cast(TrueVal)) && + !CFPt->getValueAPF().isZero()) || + ((CFPf = dyn_cast(FalseVal)) && + !CFPf->getValueAPF().isZero())) + return replaceInstUsesWith(SI, TrueVal); + } - if (Value *V = SimplifySelectInst(CondVal, TrueVal, FalseVal, - SQ.getWithInstruction(&SI))) - return replaceInstUsesWith(SI, V); + // Canonicalize to use ordered comparisons by swapping the select + // operands. + // + // e.g. + // (X ugt Y) ? X : Y -> (X ole Y) ? X : Y + if (FCI->hasOneUse() && FCmpInst::isUnordered(FCI->getPredicate())) { + FCmpInst::Predicate InvPred = FCI->getInversePredicate(); + IRBuilder<>::FastMathFlagGuard FMFG(Builder); + Builder.setFastMathFlags(FCI->getFastMathFlags()); + Value *NewCond = Builder.CreateFCmp(InvPred, FalseVal, TrueVal, + FCI->getName() + ".inv"); - if (Instruction *I = canonicalizeSelectToShuffle(SI)) - return I; + return SelectInst::Create(NewCond, FalseVal, TrueVal, + SI.getName() + ".p"); + } - // Canonicalize a one-use integer compare with a non-canonical predicate by - // inverting the predicate and swapping the select operands. This matches a - // compare canonicalization for conditional branches. - // TODO: Should we do the same for FP compares? - CmpInst::Predicate Pred; - if (match(CondVal, m_OneUse(m_ICmp(Pred, m_Value(), m_Value()))) && - !isCanonicalPredicate(Pred)) { - // Swap true/false values and condition. - CmpInst *Cond = cast(CondVal); - Cond->setPredicate(CmpInst::getInversePredicate(Pred)); - SI.setOperand(1, FalseVal); - SI.setOperand(2, TrueVal); - SI.swapProfMetadata(); - Worklist.Add(Cond); - return &SI; - } - - if (SelType->isIntOrIntVectorTy(1) && - TrueVal->getType() == CondVal->getType()) { - if (match(TrueVal, m_One())) { - // Change: A = select B, true, C --> A = or B, C - return BinaryOperator::CreateOr(CondVal, FalseVal); - } - if (match(TrueVal, m_Zero())) { - // Change: A = select B, false, C --> A = and !B, C - Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName()); - return BinaryOperator::CreateAnd(NotCond, FalseVal); - } - if (match(FalseVal, m_Zero())) { - // Change: A = select B, C, false --> A = and B, C - return BinaryOperator::CreateAnd(CondVal, TrueVal); - } - if (match(FalseVal, m_One())) { - // Change: A = select B, C, true --> A = or !B, C - Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName()); - return BinaryOperator::CreateOr(NotCond, TrueVal); - } - - // select a, a, b -> a | b - // select a, b, a -> a & b - if (CondVal == TrueVal) - return BinaryOperator::CreateOr(CondVal, FalseVal); - if (CondVal == FalseVal) - return BinaryOperator::CreateAnd(CondVal, TrueVal); - - // select a, ~a, b -> (~a) & b - // select a, b, ~a -> (~a) | b - if (match(TrueVal, m_Not(m_Specific(CondVal)))) - return BinaryOperator::CreateAnd(TrueVal, FalseVal); - if (match(FalseVal, m_Not(m_Specific(CondVal)))) - return BinaryOperator::CreateOr(TrueVal, FalseVal); - } - - // Selecting between two integer or vector splat integer constants? - // - // Note that we don't handle a scalar select of vectors: - // select i1 %c, <2 x i8> <1, 1>, <2 x i8> <0, 0> - // because that may need 3 instructions to splat the condition value: - // extend, insertelement, shufflevector. - if (SelType->isIntOrIntVectorTy() && - CondVal->getType()->isVectorTy() == SelType->isVectorTy()) { - // select C, 1, 0 -> zext C to int - if (match(TrueVal, m_One()) && match(FalseVal, m_Zero())) - return new ZExtInst(CondVal, SelType); - - // select C, -1, 0 -> sext C to int - if (match(TrueVal, m_AllOnes()) && match(FalseVal, m_Zero())) - return new SExtInst(CondVal, SelType); - - // select C, 0, 1 -> zext !C to int - if (match(TrueVal, m_Zero()) && match(FalseVal, m_One())) { - Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName()); - return new ZExtInst(NotCond, SelType); - } - - // select C, 0, -1 -> sext !C to int - if (match(TrueVal, m_Zero()) && match(FalseVal, m_AllOnes())) { - Value *NotCond = Builder.CreateNot(CondVal, "not." + CondVal->getName()); - return new SExtInst(NotCond, SelType); - } - } - - // See if we are selecting two values based on a comparison of the two values. - if (FCmpInst *FCI = dyn_cast(CondVal)) { - if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) { - // Transform (X == Y) ? X : Y -> Y - if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) { - // This is not safe in general for floating point: - // consider X== -0, Y== +0. - // It becomes safe if either operand is a nonzero constant. - ConstantFP *CFPt, *CFPf; - if (((CFPt = dyn_cast(TrueVal)) && - !CFPt->getValueAPF().isZero()) || - ((CFPf = dyn_cast(FalseVal)) && - !CFPf->getValueAPF().isZero())) - return replaceInstUsesWith(SI, FalseVal); + // NOTE: if we wanted to, this is where to detect MIN/MAX } - // Transform (X une Y) ? X : Y -> X - if (FCI->getPredicate() == FCmpInst::FCMP_UNE) { - // This is not safe in general for floating point: - // consider X== -0, Y== +0. - // It becomes safe if either operand is a nonzero constant. - ConstantFP *CFPt, *CFPf; - if (((CFPt = dyn_cast(TrueVal)) && - !CFPt->getValueAPF().isZero()) || - ((CFPf = dyn_cast(FalseVal)) && - !CFPf->getValueAPF().isZero())) - return replaceInstUsesWith(SI, TrueVal); + + // Canonicalize select with fcmp to fabs(). -0.0 makes this tricky. We + // need + // fast-math-flags (nsz) or fsub with +0.0 (not fneg) for this to work. We + // also require nnan because we do not want to unintentionally change the + // sign of a NaN value. + Value *X = FCI->getOperand(0); + FCmpInst::Predicate Pred = FCI->getPredicate(); + if (match(FCI->getOperand(1), m_AnyZeroFP()) && FCI->hasNoNaNs()) { + // (X <= +/-0.0) ? (0.0 - X) : X --> fabs(X) + // (X > +/-0.0) ? X : (0.0 - X) --> fabs(X) + if ((X == FalseVal && Pred == FCmpInst::FCMP_OLE && + match(TrueVal, m_FSub(m_PosZeroFP(), m_Specific(X)))) || + (X == TrueVal && Pred == FCmpInst::FCMP_OGT && + match(FalseVal, m_FSub(m_PosZeroFP(), m_Specific(X))))) { + Value *Fabs = Builder.CreateIntrinsic(Intrinsic::fabs, {X}, FCI); + return replaceInstUsesWith(SI, Fabs); + } + // With nsz: + // (X < +/-0.0) ? -X : X --> fabs(X) + // (X <= +/-0.0) ? -X : X --> fabs(X) + // (X > +/-0.0) ? X : -X --> fabs(X) + // (X >= +/-0.0) ? X : -X --> fabs(X) + if (FCI->hasNoSignedZeros() && + ((X == FalseVal && match(TrueVal, m_FNeg(m_Specific(X))) && + (Pred == FCmpInst::FCMP_OLT || Pred == FCmpInst::FCMP_OLE)) || + (X == TrueVal && match(FalseVal, m_FNeg(m_Specific(X))) && + (Pred == FCmpInst::FCMP_OGT || Pred == FCmpInst::FCMP_OGE)))) { + Value *Fabs = Builder.CreateIntrinsic(Intrinsic::fabs, {X}, FCI); + return replaceInstUsesWith(SI, Fabs); + } } + } - // Canonicalize to use ordered comparisons by swapping the select - // operands. - // - // e.g. - // (X ugt Y) ? X : Y -> (X ole Y) ? Y : X - if (FCI->hasOneUse() && FCmpInst::isUnordered(FCI->getPredicate())) { - FCmpInst::Predicate InvPred = FCI->getInversePredicate(); - IRBuilder<>::FastMathFlagGuard FMFG(Builder); - Builder.setFastMathFlags(FCI->getFastMathFlags()); - Value *NewCond = Builder.CreateFCmp(InvPred, TrueVal, FalseVal, - FCI->getName() + ".inv"); - - return SelectInst::Create(NewCond, FalseVal, TrueVal, - SI.getName() + ".p"); - } - - // NOTE: if we wanted to, this is where to detect MIN/MAX - } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){ - // Transform (X == Y) ? Y : X -> X - if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) { - // This is not safe in general for floating point: - // consider X== -0, Y== +0. - // It becomes safe if either operand is a nonzero constant. - ConstantFP *CFPt, *CFPf; - if (((CFPt = dyn_cast(TrueVal)) && - !CFPt->getValueAPF().isZero()) || - ((CFPf = dyn_cast(FalseVal)) && - !CFPf->getValueAPF().isZero())) - return replaceInstUsesWith(SI, FalseVal); - } - // Transform (X une Y) ? Y : X -> Y - if (FCI->getPredicate() == FCmpInst::FCMP_UNE) { - // This is not safe in general for floating point: - // consider X== -0, Y== +0. - // It becomes safe if either operand is a nonzero constant. - ConstantFP *CFPt, *CFPf; - if (((CFPt = dyn_cast(TrueVal)) && - !CFPt->getValueAPF().isZero()) || - ((CFPf = dyn_cast(FalseVal)) && - !CFPf->getValueAPF().isZero())) - return replaceInstUsesWith(SI, TrueVal); - } - - // Canonicalize to use ordered comparisons by swapping the select - // operands. - // - // e.g. - // (X ugt Y) ? X : Y -> (X ole Y) ? X : Y - if (FCI->hasOneUse() && FCmpInst::isUnordered(FCI->getPredicate())) { - FCmpInst::Predicate InvPred = FCI->getInversePredicate(); - IRBuilder<>::FastMathFlagGuard FMFG(Builder); - Builder.setFastMathFlags(FCI->getFastMathFlags()); - Value *NewCond = Builder.CreateFCmp(InvPred, FalseVal, TrueVal, - FCI->getName() + ".inv"); - - return SelectInst::Create(NewCond, FalseVal, TrueVal, - SI.getName() + ".p"); - } - - // NOTE: if we wanted to, this is where to detect MIN/MAX - } - - // Canonicalize select with fcmp to fabs(). -0.0 makes this tricky. We need - // fast-math-flags (nsz) or fsub with +0.0 (not fneg) for this to work. We - // also require nnan because we do not want to unintentionally change the - // sign of a NaN value. - Value *X = FCI->getOperand(0); - FCmpInst::Predicate Pred = FCI->getPredicate(); - if (match(FCI->getOperand(1), m_AnyZeroFP()) && FCI->hasNoNaNs()) { - // (X <= +/-0.0) ? (0.0 - X) : X --> fabs(X) - // (X > +/-0.0) ? X : (0.0 - X) --> fabs(X) - if ((X == FalseVal && Pred == FCmpInst::FCMP_OLE && - match(TrueVal, m_FSub(m_PosZeroFP(), m_Specific(X)))) || - (X == TrueVal && Pred == FCmpInst::FCMP_OGT && - match(FalseVal, m_FSub(m_PosZeroFP(), m_Specific(X))))) { - Value *Fabs = Builder.CreateIntrinsic(Intrinsic::fabs, { X }, FCI); - return replaceInstUsesWith(SI, Fabs); - } - // With nsz: - // (X < +/-0.0) ? -X : X --> fabs(X) - // (X <= +/-0.0) ? -X : X --> fabs(X) - // (X > +/-0.0) ? X : -X --> fabs(X) - // (X >= +/-0.0) ? X : -X --> fabs(X) - if (FCI->hasNoSignedZeros() && - ((X == FalseVal && match(TrueVal, m_FNeg(m_Specific(X))) && - (Pred == FCmpInst::FCMP_OLT || Pred == FCmpInst::FCMP_OLE)) || - (X == TrueVal && match(FalseVal, m_FNeg(m_Specific(X))) && - (Pred == FCmpInst::FCMP_OGT || Pred == FCmpInst::FCMP_OGE)))) { - Value *Fabs = Builder.CreateIntrinsic(Intrinsic::fabs, { X }, FCI); - return replaceInstUsesWith(SI, Fabs); - } - } - } - - // See if we are selecting two values based on a comparison of the two values. - if (ICmpInst *ICI = dyn_cast(CondVal)) - if (Instruction *Result = foldSelectInstWithICmp(SI, ICI)) - return Result; - - if (Instruction *Add = foldAddSubSelect(SI, Builder)) - return Add; - - // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z)) - auto *TI = dyn_cast(TrueVal); - auto *FI = dyn_cast(FalseVal); - if (TI && FI && TI->getOpcode() == FI->getOpcode()) - if (Instruction *IV = foldSelectOpOp(SI, TI, FI)) - return IV; - - if (Instruction *I = foldSelectExtConst(SI)) - return I; - - // See if we can fold the select into one of our operands. - if (SelType->isIntOrIntVectorTy() || SelType->isFPOrFPVectorTy()) { - if (Instruction *FoldI = foldSelectIntoOp(SI, TrueVal, FalseVal)) - return FoldI; - - Value *LHS, *RHS, *LHS2, *RHS2; - Instruction::CastOps CastOp; - SelectPatternResult SPR = matchSelectPattern(&SI, LHS, RHS, &CastOp); - auto SPF = SPR.Flavor; - - if (SelectPatternResult::isMinOrMax(SPF)) { - // Canonicalize so that - // - type casts are outside select patterns. - // - float clamp is transformed to min/max pattern - - bool IsCastNeeded = LHS->getType() != SelType; - Value *CmpLHS = cast(CondVal)->getOperand(0); - Value *CmpRHS = cast(CondVal)->getOperand(1); - if (IsCastNeeded || - (LHS->getType()->isFPOrFPVectorTy() && - ((CmpLHS != LHS && CmpLHS != RHS) || - (CmpRHS != LHS && CmpRHS != RHS)))) { - CmpInst::Predicate Pred = getMinMaxPred(SPF, SPR.Ordered); - - Value *Cmp; - if (CmpInst::isIntPredicate(Pred)) { - Cmp = Builder.CreateICmp(Pred, LHS, RHS); - } else { - IRBuilder<>::FastMathFlagGuard FMFG(Builder); - auto FMF = cast(SI.getCondition())->getFastMathFlags(); - Builder.setFastMathFlags(FMF); - Cmp = Builder.CreateFCmp(Pred, LHS, RHS); + // See if we are selecting two values based on a comparison of the two + // values. + if (ICmpInst *ICI = dyn_cast(CondVal)) + if (Instruction *Result = foldSelectInstWithICmp(SI, ICI)) + return Result; + + if (Instruction *Add = foldAddSubSelect(SI, Builder)) + return Add; + + // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z)) + auto *TI = dyn_cast(TrueVal); + auto *FI = dyn_cast(FalseVal); + if (TI && FI && TI->getOpcode() == FI->getOpcode()) + if (Instruction *IV = foldSelectOpOp(SI, TI, FI)) + return IV; + + if (Instruction *I = foldSelectExtConst(SI)) + return I; + + // See if we can fold the select into one of our operands. + if (SelType->isIntOrIntVectorTy() || SelType->isFPOrFPVectorTy()) { + if (Instruction *FoldI = foldSelectIntoOp(SI, TrueVal, FalseVal)) + return FoldI; + + Value *LHS, *RHS, *LHS2, *RHS2; + Instruction::CastOps CastOp; + SelectPatternResult SPR = matchSelectPattern(&SI, LHS, RHS, &CastOp); + auto SPF = SPR.Flavor; + + if (SelectPatternResult::isMinOrMax(SPF)) { + // Canonicalize so that + // - type casts are outside select patterns. + // - float clamp is transformed to min/max pattern + + bool IsCastNeeded = LHS->getType() != SelType; + Value *CmpLHS = cast(CondVal)->getOperand(0); + Value *CmpRHS = cast(CondVal)->getOperand(1); + if (IsCastNeeded || (LHS->getType()->isFPOrFPVectorTy() && + ((CmpLHS != LHS && CmpLHS != RHS) || + (CmpRHS != LHS && CmpRHS != RHS)))) { + CmpInst::Predicate Pred = getMinMaxPred(SPF, SPR.Ordered); + + Value *Cmp; + if (CmpInst::isIntPredicate(Pred)) { + Cmp = Builder.CreateICmp(Pred, LHS, RHS); + } else { + IRBuilder<>::FastMathFlagGuard FMFG(Builder); + auto FMF = + cast(SI.getCondition())->getFastMathFlags(); + Builder.setFastMathFlags(FMF); + Cmp = Builder.CreateFCmp(Pred, LHS, RHS); + } + + Value *NewSI = Builder.CreateSelect(Cmp, LHS, RHS, SI.getName(), &SI); + if (!IsCastNeeded) + return replaceInstUsesWith(SI, NewSI); + + Value *NewCast = Builder.CreateCast(CastOp, NewSI, SelType); + return replaceInstUsesWith(SI, NewCast); } - Value *NewSI = Builder.CreateSelect(Cmp, LHS, RHS, SI.getName(), &SI); - if (!IsCastNeeded) - return replaceInstUsesWith(SI, NewSI); + // MAX(~a, ~b) -> ~MIN(a, b) + // MIN(~a, ~b) -> ~MAX(a, b) + Value *A, *B; + if (match(LHS, m_Not(m_Value(A))) && match(RHS, m_Not(m_Value(B))) && + (LHS->getNumUses() <= 2 || RHS->getNumUses() <= 2)) { + CmpInst::Predicate InvertedPred = getInverseMinMaxPred(SPF); + Value *InvertedCmp = Builder.CreateICmp(InvertedPred, A, B); + Value *NewSel = Builder.CreateSelect(InvertedCmp, A, B); + return BinaryOperator::CreateNot(NewSel); + } - Value *NewCast = Builder.CreateCast(CastOp, NewSI, SelType); - return replaceInstUsesWith(SI, NewCast); + if (Instruction *I = factorizeMinMaxTree(SPF, LHS, RHS, Builder)) + return I; } - // MAX(~a, ~b) -> ~MIN(a, b) - // MIN(~a, ~b) -> ~MAX(a, b) - Value *A, *B; - if (match(LHS, m_Not(m_Value(A))) && match(RHS, m_Not(m_Value(B))) && - (LHS->getNumUses() <= 2 || RHS->getNumUses() <= 2)) { - CmpInst::Predicate InvertedPred = getInverseMinMaxPred(SPF); - Value *InvertedCmp = Builder.CreateICmp(InvertedPred, A, B); - Value *NewSel = Builder.CreateSelect(InvertedCmp, A, B); - return BinaryOperator::CreateNot(NewSel); + if (SPF) { + // MAX(MAX(a, b), a) -> MAX(a, b) + // MIN(MIN(a, b), a) -> MIN(a, b) + // MAX(MIN(a, b), a) -> a + // MIN(MAX(a, b), a) -> a + // ABS(ABS(a)) -> ABS(a) + // NABS(NABS(a)) -> NABS(a) + if (SelectPatternFlavor SPF2 = + matchSelectPattern(LHS, LHS2, RHS2).Flavor) + if (Instruction *R = foldSPFofSPF(cast(LHS), SPF2, LHS2, + RHS2, SI, SPF, RHS)) + return R; + if (SelectPatternFlavor SPF2 = + matchSelectPattern(RHS, LHS2, RHS2).Flavor) + if (Instruction *R = foldSPFofSPF(cast(RHS), SPF2, LHS2, + RHS2, SI, SPF, LHS)) + return R; + } + + // TODO. + // ABS(-X) -> ABS(X) + } + + // See if we can fold the select into a phi node if the condition is a + // select. + if (auto *PN = dyn_cast(SI.getCondition())) + // The true/false values have to be live in the PHI predecessor's blocks. + if (canSelectOperandBeMappingIntoPredBlock(TrueVal, SI) && + canSelectOperandBeMappingIntoPredBlock(FalseVal, SI)) + if (Instruction *NV = foldOpIntoPhi(SI, PN)) + return NV; + + if (SelectInst *TrueSI = dyn_cast(TrueVal)) { + if (TrueSI->getCondition()->getType() == CondVal->getType()) { + // select(C, select(C, a, b), c) -> select(C, a, c) + if (TrueSI->getCondition() == CondVal) { + if (SI.getTrueValue() == TrueSI->getTrueValue()) + return nullptr; + SI.setOperand(1, TrueSI->getTrueValue()); + return &SI; + } + // select(C0, select(C1, a, b), b) -> select(C0&C1, a, b) + // We choose this as normal form to enable folding on the And and + // shortening + // paths for the values (this helps GetUnderlyingObjects() for example). + if (TrueSI->getFalseValue() == FalseVal && TrueSI->hasOneUse()) { + Value *And = Builder.CreateAnd(CondVal, TrueSI->getCondition()); + SI.setOperand(0, And); + SI.setOperand(1, TrueSI->getTrueValue()); + return &SI; + } + } + } + if (SelectInst *FalseSI = dyn_cast(FalseVal)) { + if (FalseSI->getCondition()->getType() == CondVal->getType()) { + // select(C, a, select(C, b, c)) -> select(C, a, c) + if (FalseSI->getCondition() == CondVal) { + if (SI.getFalseValue() == FalseSI->getFalseValue()) + return nullptr; + SI.setOperand(2, FalseSI->getFalseValue()); + return &SI; + } + // select(C0, a, select(C1, a, b)) -> select(C0|C1, a, b) + if (FalseSI->getTrueValue() == TrueVal && FalseSI->hasOneUse()) { + Value *Or = Builder.CreateOr(CondVal, FalseSI->getCondition()); + SI.setOperand(0, Or); + SI.setOperand(2, FalseSI->getFalseValue()); + return &SI; + } } - - if (Instruction *I = factorizeMinMaxTree(SPF, LHS, RHS, Builder)) - return I; } - if (SPF) { - // MAX(MAX(a, b), a) -> MAX(a, b) - // MIN(MIN(a, b), a) -> MIN(a, b) - // MAX(MIN(a, b), a) -> a - // MIN(MAX(a, b), a) -> a - // ABS(ABS(a)) -> ABS(a) - // NABS(NABS(a)) -> NABS(a) - if (SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2).Flavor) - if (Instruction *R = foldSPFofSPF(cast(LHS),SPF2,LHS2,RHS2, - SI, SPF, RHS)) - return R; - if (SelectPatternFlavor SPF2 = matchSelectPattern(RHS, LHS2, RHS2).Flavor) - if (Instruction *R = foldSPFofSPF(cast(RHS),SPF2,LHS2,RHS2, - SI, SPF, LHS)) - return R; - } - - // TODO. - // ABS(-X) -> ABS(X) - } - - // See if we can fold the select into a phi node if the condition is a select. - if (auto *PN = dyn_cast(SI.getCondition())) - // The true/false values have to be live in the PHI predecessor's blocks. - if (canSelectOperandBeMappingIntoPredBlock(TrueVal, SI) && - canSelectOperandBeMappingIntoPredBlock(FalseVal, SI)) - if (Instruction *NV = foldOpIntoPhi(SI, PN)) - return NV; - - if (SelectInst *TrueSI = dyn_cast(TrueVal)) { - if (TrueSI->getCondition()->getType() == CondVal->getType()) { - // select(C, select(C, a, b), c) -> select(C, a, c) - if (TrueSI->getCondition() == CondVal) { - if (SI.getTrueValue() == TrueSI->getTrueValue()) - return nullptr; - SI.setOperand(1, TrueSI->getTrueValue()); - return &SI; + auto canMergeSelectThroughBinop = [](BinaryOperator *BO) { + // The select might be preventing a division by 0. + switch (BO->getOpcode()) { + default: + return true; + case Instruction::SRem: + case Instruction::URem: + case Instruction::SDiv: + case Instruction::UDiv: + return false; } - // select(C0, select(C1, a, b), b) -> select(C0&C1, a, b) - // We choose this as normal form to enable folding on the And and shortening - // paths for the values (this helps GetUnderlyingObjects() for example). - if (TrueSI->getFalseValue() == FalseVal && TrueSI->hasOneUse()) { - Value *And = Builder.CreateAnd(CondVal, TrueSI->getCondition()); - SI.setOperand(0, And); - SI.setOperand(1, TrueSI->getTrueValue()); - return &SI; + }; + + // Try to simplify a binop sandwiched between 2 selects with the same + // condition. + // select(C, binop(select(C, X, Y), W), Z) -> select(C, binop(X, W), Z) + BinaryOperator *TrueBO; + if (match(TrueVal, m_OneUse(m_BinOp(TrueBO))) && + canMergeSelectThroughBinop(TrueBO)) { + if (auto *TrueBOSI = dyn_cast(TrueBO->getOperand(0))) { + if (TrueBOSI->getCondition() == CondVal) { + TrueBO->setOperand(0, TrueBOSI->getTrueValue()); + Worklist.Add(TrueBO); + return &SI; + } + } + if (auto *TrueBOSI = dyn_cast(TrueBO->getOperand(1))) { + if (TrueBOSI->getCondition() == CondVal) { + TrueBO->setOperand(1, TrueBOSI->getTrueValue()); + Worklist.Add(TrueBO); + return &SI; + } } } - } - if (SelectInst *FalseSI = dyn_cast(FalseVal)) { - if (FalseSI->getCondition()->getType() == CondVal->getType()) { - // select(C, a, select(C, b, c)) -> select(C, a, c) - if (FalseSI->getCondition() == CondVal) { - if (SI.getFalseValue() == FalseSI->getFalseValue()) - return nullptr; - SI.setOperand(2, FalseSI->getFalseValue()); - return &SI; + + // select(C, Z, binop(select(C, X, Y), W)) -> select(C, Z, binop(Y, W)) + BinaryOperator *FalseBO; + if (match(FalseVal, m_OneUse(m_BinOp(FalseBO))) && + canMergeSelectThroughBinop(FalseBO)) { + if (auto *FalseBOSI = dyn_cast(FalseBO->getOperand(0))) { + if (FalseBOSI->getCondition() == CondVal) { + FalseBO->setOperand(0, FalseBOSI->getFalseValue()); + Worklist.Add(FalseBO); + return &SI; + } } - // select(C0, a, select(C1, a, b)) -> select(C0|C1, a, b) - if (FalseSI->getTrueValue() == TrueVal && FalseSI->hasOneUse()) { - Value *Or = Builder.CreateOr(CondVal, FalseSI->getCondition()); - SI.setOperand(0, Or); - SI.setOperand(2, FalseSI->getFalseValue()); - return &SI; + if (auto *FalseBOSI = dyn_cast(FalseBO->getOperand(1))) { + if (FalseBOSI->getCondition() == CondVal) { + FalseBO->setOperand(1, FalseBOSI->getFalseValue()); + Worklist.Add(FalseBO); + return &SI; + } } } - } - auto canMergeSelectThroughBinop = [](BinaryOperator *BO) { - // The select might be preventing a division by 0. - switch (BO->getOpcode()) { - default: - return true; - case Instruction::SRem: - case Instruction::URem: - case Instruction::SDiv: - case Instruction::UDiv: - return false; + if (BinaryOperator::isNot(CondVal)) { + SI.setOperand(0, BinaryOperator::getNotArgument(CondVal)); + SI.setOperand(1, FalseVal); + SI.setOperand(2, TrueVal); + return &SI; } - }; - // Try to simplify a binop sandwiched between 2 selects with the same - // condition. - // select(C, binop(select(C, X, Y), W), Z) -> select(C, binop(X, W), Z) - BinaryOperator *TrueBO; - if (match(TrueVal, m_OneUse(m_BinOp(TrueBO))) && - canMergeSelectThroughBinop(TrueBO)) { - if (auto *TrueBOSI = dyn_cast(TrueBO->getOperand(0))) { - if (TrueBOSI->getCondition() == CondVal) { - TrueBO->setOperand(0, TrueBOSI->getTrueValue()); - Worklist.Add(TrueBO); + if (VectorType *VecTy = dyn_cast(SelType)) { + unsigned VWidth = VecTy->getNumElements(); + APInt UndefElts(VWidth, 0); + APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth)); + if (Value *V = + SimplifyDemandedVectorElts(&SI, AllOnesEltMask, UndefElts)) { + if (V != &SI) + return replaceInstUsesWith(SI, V); return &SI; } } - if (auto *TrueBOSI = dyn_cast(TrueBO->getOperand(1))) { - if (TrueBOSI->getCondition() == CondVal) { - TrueBO->setOperand(1, TrueBOSI->getTrueValue()); - Worklist.Add(TrueBO); - return &SI; - } - } - } - // select(C, Z, binop(select(C, X, Y), W)) -> select(C, Z, binop(Y, W)) - BinaryOperator *FalseBO; - if (match(FalseVal, m_OneUse(m_BinOp(FalseBO))) && - canMergeSelectThroughBinop(FalseBO)) { - if (auto *FalseBOSI = dyn_cast(FalseBO->getOperand(0))) { - if (FalseBOSI->getCondition() == CondVal) { - FalseBO->setOperand(0, FalseBOSI->getFalseValue()); - Worklist.Add(FalseBO); - return &SI; - } - } - if (auto *FalseBOSI = dyn_cast(FalseBO->getOperand(1))) { - if (FalseBOSI->getCondition() == CondVal) { - FalseBO->setOperand(1, FalseBOSI->getFalseValue()); - Worklist.Add(FalseBO); - return &SI; + // See if we can determine the result of this select based on a dominating + // condition. + BasicBlock *Parent = SI.getParent(); + if (BasicBlock *Dom = Parent->getSinglePredecessor()) { + auto *PBI = dyn_cast_or_null(Dom->getTerminator()); + if (PBI && PBI->isConditional() && + PBI->getSuccessor(0) != PBI->getSuccessor(1) && + (PBI->getSuccessor(0) == Parent || PBI->getSuccessor(1) == Parent)) { + bool CondIsTrue = PBI->getSuccessor(0) == Parent; + Optional Implication = isImpliedCondition( + PBI->getCondition(), SI.getCondition(), DL, CondIsTrue); + if (Implication) { + Value *V = *Implication ? TrueVal : FalseVal; + return replaceInstUsesWith(SI, V); + } } } - } - if (BinaryOperator::isNot(CondVal)) { - SI.setOperand(0, BinaryOperator::getNotArgument(CondVal)); - SI.setOperand(1, FalseVal); - SI.setOperand(2, TrueVal); - return &SI; - } - - if (VectorType *VecTy = dyn_cast(SelType)) { - unsigned VWidth = VecTy->getNumElements(); - APInt UndefElts(VWidth, 0); - APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth)); - if (Value *V = SimplifyDemandedVectorElts(&SI, AllOnesEltMask, UndefElts)) { - if (V != &SI) - return replaceInstUsesWith(SI, V); - return &SI; + // If we can compute the condition, there's no need for a select. + // Like the above fold, we are attempting to reduce compile-time cost by + // putting this fold here with limitations rather than in InstSimplify. + // The motivation for this call into value tracking is to take advantage of + // the assumption cache, so make sure that is populated. + if (!CondVal->getType()->isVectorTy() && !AC.assumptions().empty()) { + KnownBits Known(1); + computeKnownBits(CondVal, Known, 0, &SI); + if (Known.One.isOneValue()) + return replaceInstUsesWith(SI, TrueVal); + if (Known.Zero.isOneValue()) + return replaceInstUsesWith(SI, FalseVal); } - } - // See if we can determine the result of this select based on a dominating - // condition. - BasicBlock *Parent = SI.getParent(); - if (BasicBlock *Dom = Parent->getSinglePredecessor()) { - auto *PBI = dyn_cast_or_null(Dom->getTerminator()); - if (PBI && PBI->isConditional() && - PBI->getSuccessor(0) != PBI->getSuccessor(1) && - (PBI->getSuccessor(0) == Parent || PBI->getSuccessor(1) == Parent)) { - bool CondIsTrue = PBI->getSuccessor(0) == Parent; - Optional Implication = isImpliedCondition( - PBI->getCondition(), SI.getCondition(), DL, CondIsTrue); - if (Implication) { - Value *V = *Implication ? TrueVal : FalseVal; - return replaceInstUsesWith(SI, V); - } - } - } + if (Instruction *BitCastSel = foldSelectCmpBitcasts(SI, Builder)) + return BitCastSel; - // If we can compute the condition, there's no need for a select. - // Like the above fold, we are attempting to reduce compile-time cost by - // putting this fold here with limitations rather than in InstSimplify. - // The motivation for this call into value tracking is to take advantage of - // the assumption cache, so make sure that is populated. - if (!CondVal->getType()->isVectorTy() && !AC.assumptions().empty()) { - KnownBits Known(1); - computeKnownBits(CondVal, Known, 0, &SI); - if (Known.One.isOneValue()) - return replaceInstUsesWith(SI, TrueVal); - if (Known.Zero.isOneValue()) - return replaceInstUsesWith(SI, FalseVal); - } - - if (Instruction *BitCastSel = foldSelectCmpBitcasts(SI, Builder)) - return BitCastSel; - - // Simplify selects that test the returned flag of cmpxchg instructions. - if (Instruction *Select = foldSelectCmpXchg(SI)) - return Select; + // Simplify selects that test the returned flag of cmpxchg instructions. + if (Instruction *Select = foldSelectCmpXchg(SI)) + return Select; - if (Instruction *Select = foldSelectBinOpIdentity(SI)) - return Select; + if (Instruction *Select = foldSelectBinOpIdentity(SI)) + return Select; - return nullptr; -} + return nullptr; + } Index: test/Transforms/InstCombine/select-binop-icmp.ll =================================================================== --- test/Transforms/InstCombine/select-binop-icmp.ll +++ test/Transforms/InstCombine/select-binop-icmp.ll @@ -137,12 +137,10 @@ ret i32 %C } -; TODO: Support for FP opcodes define float @select_fadd_icmp(float %x, float %y, float %z) { ; CHECK-LABEL: @select_fadd_icmp( ; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], -0.000000e+00 -; CHECK-NEXT: [[B:%.*]] = fadd float [[X]], [[Z:%.*]] -; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]] +; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float [[Y:%.*]] ; CHECK-NEXT: ret float [[C]] ; %A = fcmp oeq float %x, -0.0 @@ -154,8 +152,7 @@ define float @select_fadd_icmp2(float %x, float %y, float %z) { ; CHECK-LABEL: @select_fadd_icmp2( ; CHECK-NEXT: [[A:%.*]] = fcmp ueq float [[X:%.*]], -0.000000e+00 -; CHECK-NEXT: [[B:%.*]] = fadd float [[X]], [[Z:%.*]] -; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]] +; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float [[Y:%.*]] ; CHECK-NEXT: ret float [[C]] ; %A = fcmp ueq float %x, -0.0 @@ -167,8 +164,7 @@ define float @select_fmul_icmp(float %x, float %y, float %z) { ; CHECK-LABEL: @select_fmul_icmp( ; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], 1.000000e+00 -; CHECK-NEXT: [[B:%.*]] = fmul float [[X]], [[Z:%.*]] -; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]] +; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float [[Y:%.*]] ; CHECK-NEXT: ret float [[C]] ; %A = fcmp oeq float %x, 1.0 @@ -177,12 +173,10 @@ ret float %C } -; TODO: Support for non-commutative opcodes define i32 @select_sub_icmp(i32 %x, i32 %y, i32 %z) { ; CHECK-LABEL: @select_sub_icmp( ; CHECK-NEXT: [[A:%.*]] = icmp eq i32 [[X:%.*]], 0 -; CHECK-NEXT: [[B:%.*]] = sub i32 [[X]], [[Z:%.*]] -; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[B]], i32 [[Y:%.*]] +; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Z:%.*]], i32 [[Y:%.*]] ; CHECK-NEXT: ret i32 [[C]] ; %A = icmp eq i32 %x, 0 @@ -194,8 +188,7 @@ define i32 @select_shl_icmp(i32 %x, i32 %y, i32 %z) { ; CHECK-LABEL: @select_shl_icmp( ; CHECK-NEXT: [[A:%.*]] = icmp eq i32 [[X:%.*]], 0 -; CHECK-NEXT: [[B:%.*]] = shl i32 [[X]], [[Z:%.*]] -; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[B]], i32 [[Y:%.*]] +; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Z:%.*]], i32 [[Y:%.*]] ; CHECK-NEXT: ret i32 [[C]] ; %A = icmp eq i32 %x, 0 @@ -207,8 +200,7 @@ define i32 @select_lshr_icmp(i32 %x, i32 %y, i32 %z) { ; CHECK-LABEL: @select_lshr_icmp( ; CHECK-NEXT: [[A:%.*]] = icmp eq i32 [[X:%.*]], 0 -; CHECK-NEXT: [[B:%.*]] = lshr i32 [[X]], [[Z:%.*]] -; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[B]], i32 [[Y:%.*]] +; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Z:%.*]], i32 [[Y:%.*]] ; CHECK-NEXT: ret i32 [[C]] ; %A = icmp eq i32 %x, 0 @@ -220,8 +212,7 @@ define i32 @select_ashr_icmp(i32 %x, i32 %y, i32 %z) { ; CHECK-LABEL: @select_ashr_icmp( ; CHECK-NEXT: [[A:%.*]] = icmp eq i32 [[X:%.*]], 0 -; CHECK-NEXT: [[B:%.*]] = ashr i32 [[X]], [[Z:%.*]] -; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[B]], i32 [[Y:%.*]] +; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], i32 [[Z:%.*]], i32 [[Y:%.*]] ; CHECK-NEXT: ret i32 [[C]] ; %A = icmp eq i32 %x, 0