X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FInstructionSimplify.cpp;h=459fc92bce1a856a2d621b6aedc24c76c18c2d1a;hb=25529b337f75a4b9b174592e2c95136e781bd824;hp=4c621b0e9110492b7a01cba4b6795aad788ee57a;hpb=4da253756ddc62496ad5baf7a8efaf2f001ef92a;p=oota-llvm.git diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp index 4c621b0e911..459fc92bce1 100644 --- a/lib/Analysis/InstructionSimplify.cpp +++ b/lib/Analysis/InstructionSimplify.cpp @@ -39,7 +39,6 @@ using namespace llvm::PatternMatch; enum { RecursionLimit = 3 }; STATISTIC(NumExpand, "Number of expansions"); -STATISTIC(NumFactor , "Number of factorizations"); STATISTIC(NumReassoc, "Number of reassociations"); struct Query { @@ -183,78 +182,6 @@ static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS, return nullptr; } -/// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term -/// using the operation OpCodeToExtract. For example, when Opcode is Add and -/// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)". -/// Returns the simplified value, or null if no simplification was performed. -static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS, - unsigned OpcToExtract, const Query &Q, - unsigned MaxRecurse) { - Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract; - // Recursion is always used, so bail out at once if we already hit the limit. - if (!MaxRecurse--) - return nullptr; - - BinaryOperator *Op0 = dyn_cast(LHS); - BinaryOperator *Op1 = dyn_cast(RHS); - - if (!Op0 || Op0->getOpcode() != OpcodeToExtract || - !Op1 || Op1->getOpcode() != OpcodeToExtract) - return nullptr; - - // The expression has the form "(A op' B) op (C op' D)". - Value *A = Op0->getOperand(0), *B = Op0->getOperand(1); - Value *C = Op1->getOperand(0), *D = Op1->getOperand(1); - - // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)". - // Does the instruction have the form "(A op' B) op (A op' D)" or, in the - // commutative case, "(A op' B) op (C op' A)"? - if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) { - Value *DD = A == C ? D : C; - // Form "A op' (B op DD)" if it simplifies completely. - // Does "B op DD" simplify? - if (Value *V = SimplifyBinOp(Opcode, B, DD, Q, MaxRecurse)) { - // It does! Return "A op' V" if it simplifies or is already available. - // If V equals B then "A op' V" is just the LHS. If V equals DD then - // "A op' V" is just the RHS. - if (V == B || V == DD) { - ++NumFactor; - return V == B ? LHS : RHS; - } - // Otherwise return "A op' V" if it simplifies. - if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, Q, MaxRecurse)) { - ++NumFactor; - return W; - } - } - } - - // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)". - // Does the instruction have the form "(A op' B) op (C op' B)" or, in the - // commutative case, "(A op' B) op (B op' D)"? - if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) { - Value *CC = B == D ? C : D; - // Form "(A op CC) op' B" if it simplifies completely.. - // Does "A op CC" simplify? - if (Value *V = SimplifyBinOp(Opcode, A, CC, Q, MaxRecurse)) { - // It does! Return "V op' B" if it simplifies or is already available. - // If V equals A then "V op' B" is just the LHS. If V equals CC then - // "V op' B" is just the RHS. - if (V == A || V == CC) { - ++NumFactor; - return V == A ? LHS : RHS; - } - // Otherwise return "V op' B" if it simplifies. - if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, Q, MaxRecurse)) { - ++NumFactor; - return W; - } - } - } - - return nullptr; -} - /// SimplifyAssociativeBinOp - Generic simplifications for associative binary /// operations. Returns the simpler value, or null if none was found. static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS, @@ -634,11 +561,6 @@ static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, MaxRecurse)) return V; - // Mul distributes over Add. Try some generic simplifications based on this. - if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul, - Q, MaxRecurse)) - return V; - // Threading Add over selects and phi nodes is pointless, so don't bother. // Threading over the select in "A + select(cond, B, C)" means evaluating // "A+B" and "A+C" and seeing if they are equal; but they are equal if and @@ -754,16 +676,21 @@ static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, if (Op0 == Op1) return Constant::getNullValue(Op0->getType()); - // (X*2) - X -> X - // (X<<1) - X -> X - Value *X = nullptr; - if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) || - match(Op0, m_Shl(m_Specific(Op1), m_One()))) - return Op1; + // X - (0 - Y) -> X if the second sub is NUW. + // If Y != 0, 0 - Y is a poison value. + // If Y == 0, 0 - Y simplifies to 0. + if (BinaryOperator::isNeg(Op1)) { + if (const auto *BO = dyn_cast(Op1)) { + assert(BO->getOpcode() == Instruction::Sub && + "Expected a subtraction operator!"); + if (BO->hasNoUnsignedWrap()) + return Op0; + } + } // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies. // For example, (X + Y) - Y -> X; (Y + X) - Y -> X - Value *Y = nullptr, *Z = Op1; + Value *X = nullptr, *Y = nullptr, *Z = Op1; if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z // See if "V === Y - Z" simplifies. if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1)) @@ -835,11 +762,6 @@ static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, if (Constant *Result = computePointerDifference(Q.DL, X, Y)) return ConstantExpr::getIntegerCast(Result, Op0->getType(), true); - // Mul distributes over Sub. Try some generic simplifications based on this. - if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul, - Q, MaxRecurse)) - return V; - // i1 sub -> xor. if (MaxRecurse && Op0->getType()->isIntegerTy(1)) if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1)) @@ -1436,6 +1358,11 @@ static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, cast(Op0)->hasNoSignedWrap()) return X; + // Arithmetic shifting an all-sign-bit value is a no-op. + unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL); + if (NumSignBits == Op0->getType()->getScalarSizeInBits()) + return Op0; + return nullptr; } @@ -1518,11 +1445,6 @@ static Value *SimplifyAndInst(Value *Op0, Value *Op1, const Query &Q, Q, MaxRecurse)) return V; - // Or distributes over And. Try some generic simplifications based on this. - if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or, - Q, MaxRecurse)) - return V; - // If the operation is with the result of a select instruction, check whether // operating on either branch of the select always yields the same value. if (isa(Op0) || isa(Op1)) @@ -1613,11 +1535,6 @@ static Value *SimplifyOrInst(Value *Op0, Value *Op1, const Query &Q, MaxRecurse)) return V; - // And distributes over Or. Try some generic simplifications based on this. - if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And, - Q, MaxRecurse)) - return V; - // If the operation is with the result of a select instruction, check whether // operating on either branch of the select always yields the same value. if (isa(Op0) || isa(Op1)) @@ -1625,6 +1542,38 @@ static Value *SimplifyOrInst(Value *Op0, Value *Op1, const Query &Q, MaxRecurse)) return V; + // (A & C)|(B & D) + Value *C = nullptr, *D = nullptr; + if (match(Op0, m_And(m_Value(A), m_Value(C))) && + match(Op1, m_And(m_Value(B), m_Value(D)))) { + ConstantInt *C1 = dyn_cast(C); + ConstantInt *C2 = dyn_cast(D); + if (C1 && C2 && (C1->getValue() == ~C2->getValue())) { + // (A & C1)|(B & C2) + // If we have: ((V + N) & C1) | (V & C2) + // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0 + // replace with V+N. + Value *V1, *V2; + if ((C2->getValue() & (C2->getValue() + 1)) == 0 && // C2 == 0+1+ + match(A, m_Add(m_Value(V1), m_Value(V2)))) { + // Add commutes, try both ways. + if (V1 == B && MaskedValueIsZero(V2, C2->getValue())) + return A; + if (V2 == B && MaskedValueIsZero(V1, C2->getValue())) + return A; + } + // Or commutes, try both ways. + if ((C1->getValue() & (C1->getValue() + 1)) == 0 && + match(B, m_Add(m_Value(V1), m_Value(V2)))) { + // Add commutes, try both ways. + if (V1 == A && MaskedValueIsZero(V2, C1->getValue())) + return B; + if (V2 == A && MaskedValueIsZero(V1, C1->getValue())) + return B; + } + } + } + // If the operation is with the result of a phi instruction, check whether // operating on all incoming values of the phi always yields the same value. if (isa(Op0) || isa(Op1)) @@ -1677,11 +1626,6 @@ static Value *SimplifyXorInst(Value *Op0, Value *Op1, const Query &Q, MaxRecurse)) return V; - // And distributes over Xor. Try some generic simplifications based on this. - if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And, - Q, MaxRecurse)) - return V; - // Threading Xor over selects and phi nodes is pointless, so don't bother. // Threading over the select in "A ^ select(cond, B, C)" means evaluating // "A^B" and "A^C" and seeing if they are equal; but they are equal if and @@ -2001,7 +1945,7 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, // Many binary operators with constant RHS have easy to compute constant // range. Use them to check whether the comparison is a tautology. - uint32_t Width = CI->getBitWidth(); + unsigned Width = CI->getBitWidth(); APInt Lower = APInt(Width, 0); APInt Upper = APInt(Width, 0); ConstantInt *CI2; @@ -2020,20 +1964,47 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, APInt NegOne = APInt::getAllOnesValue(Width); if (!CI2->isZero()) Upper = NegOne.udiv(CI2->getValue()) + 1; + } else if (match(LHS, m_SDiv(m_ConstantInt(CI2), m_Value()))) { + if (CI2->isMinSignedValue()) { + // 'sdiv INT_MIN, x' produces [INT_MIN, INT_MIN / -2]. + Lower = CI2->getValue(); + Upper = Lower.lshr(1) + 1; + } else { + // 'sdiv CI2, x' produces [-|CI2|, |CI2|]. + Upper = CI2->getValue().abs() + 1; + Lower = (-Upper) + 1; + } } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) { - // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2]. APInt IntMin = APInt::getSignedMinValue(Width); APInt IntMax = APInt::getSignedMaxValue(Width); - APInt Val = CI2->getValue().abs(); - if (!Val.isMinValue()) { + APInt Val = CI2->getValue(); + if (Val.isAllOnesValue()) { + // 'sdiv x, -1' produces [INT_MIN + 1, INT_MAX] + // where CI2 != -1 and CI2 != 0 and CI2 != 1 + Lower = IntMin + 1; + Upper = IntMax + 1; + } else if (Val.countLeadingZeros() < Width - 1) { + // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2] + // where CI2 != -1 and CI2 != 0 and CI2 != 1 Lower = IntMin.sdiv(Val); - Upper = IntMax.sdiv(Val) + 1; + Upper = IntMax.sdiv(Val); + if (Lower.sgt(Upper)) + std::swap(Lower, Upper); + Upper = Upper + 1; + assert(Upper != Lower && "Upper part of range has wrapped!"); } } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) { // 'lshr x, CI2' produces [0, UINT_MAX >> CI2]. APInt NegOne = APInt::getAllOnesValue(Width); if (CI2->getValue().ult(Width)) Upper = NegOne.lshr(CI2->getValue()) + 1; + } else if (match(LHS, m_LShr(m_ConstantInt(CI2), m_Value()))) { + // 'lshr CI2, x' produces [CI2 >> (Width-1), CI2]. + unsigned ShiftAmount = Width - 1; + if (!CI2->isZero() && cast(LHS)->isExact()) + ShiftAmount = CI2->getValue().countTrailingZeros(); + Lower = CI2->getValue().lshr(ShiftAmount); + Upper = CI2->getValue() + 1; } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) { // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2]. APInt IntMin = APInt::getSignedMinValue(Width); @@ -2042,6 +2013,19 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, Lower = IntMin.ashr(CI2->getValue()); Upper = IntMax.ashr(CI2->getValue()) + 1; } + } else if (match(LHS, m_AShr(m_ConstantInt(CI2), m_Value()))) { + unsigned ShiftAmount = Width - 1; + if (!CI2->isZero() && cast(LHS)->isExact()) + ShiftAmount = CI2->getValue().countTrailingZeros(); + if (CI2->isNegative()) { + // 'ashr CI2, x' produces [CI2, CI2 >> (Width-1)] + Lower = CI2->getValue(); + Upper = CI2->getValue().ashr(ShiftAmount) + 1; + } else { + // 'ashr CI2, x' produces [CI2 >> (Width-1), CI2] + Lower = CI2->getValue().ashr(ShiftAmount); + Upper = CI2->getValue() + 1; + } } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) { // 'or x, CI2' produces [CI2, UINT_MAX]. Lower = CI2->getValue(); @@ -2217,6 +2201,25 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, } } + // If a bit is known to be zero for A and known to be one for B, + // then A and B cannot be equal. + if (ICmpInst::isEquality(Pred)) { + if (ConstantInt *CI = dyn_cast(RHS)) { + uint32_t BitWidth = CI->getBitWidth(); + APInt LHSKnownZero(BitWidth, 0); + APInt LHSKnownOne(BitWidth, 0); + computeKnownBits(LHS, LHSKnownZero, LHSKnownOne); + APInt RHSKnownZero(BitWidth, 0); + APInt RHSKnownOne(BitWidth, 0); + computeKnownBits(RHS, RHSKnownZero, RHSKnownOne); + if (((LHSKnownOne & RHSKnownZero) != 0) || + ((LHSKnownZero & RHSKnownOne) != 0)) + return (Pred == ICmpInst::ICMP_EQ) + ? ConstantInt::getFalse(CI->getContext()) + : ConstantInt::getTrue(CI->getContext()); + } + } + // Special logic for binary operators. BinaryOperator *LBO = dyn_cast(LHS); BinaryOperator *RBO = dyn_cast(RHS); @@ -2280,6 +2283,28 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, } } + // 0 - (zext X) pred C + if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) { + if (ConstantInt *RHSC = dyn_cast(RHS)) { + if (RHSC->getValue().isStrictlyPositive()) { + if (Pred == ICmpInst::ICMP_SLT) + return ConstantInt::getTrue(RHSC->getContext()); + if (Pred == ICmpInst::ICMP_SGE) + return ConstantInt::getFalse(RHSC->getContext()); + if (Pred == ICmpInst::ICMP_EQ) + return ConstantInt::getFalse(RHSC->getContext()); + if (Pred == ICmpInst::ICMP_NE) + return ConstantInt::getTrue(RHSC->getContext()); + } + if (RHSC->getValue().isNonNegative()) { + if (Pred == ICmpInst::ICMP_SLE) + return ConstantInt::getTrue(RHSC->getContext()); + if (Pred == ICmpInst::ICMP_SGT) + return ConstantInt::getFalse(RHSC->getContext()); + } + } + } + // icmp pred (urem X, Y), Y if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) { bool KnownNonNegative, KnownNegative;