X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FTransforms%2FScalar%2FReassociate.cpp;h=b677523d70328d19d528635e541be02551cc0ef6;hb=f3bad3fece05e87f02d6d33af0534840d9df8801;hp=7cde3ab6be8ccad9e192b13509f3756364537ef8;hpb=2244d9a5d25dbb9290250935eec6a319c0026c49;p=oota-llvm.git diff --git a/lib/Transforms/Scalar/Reassociate.cpp b/lib/Transforms/Scalar/Reassociate.cpp index 7cde3ab6be8..b677523d703 100644 --- a/lib/Transforms/Scalar/Reassociate.cpp +++ b/lib/Transforms/Scalar/Reassociate.cpp @@ -59,7 +59,7 @@ namespace { } #ifndef NDEBUG -/// PrintOps - Print out the expression identified in the Ops list. +/// Print out the expression identified in the Ops list. /// static void PrintOps(Instruction *I, const SmallVectorImpl &Ops) { Module *M = I->getParent()->getParent()->getParent(); @@ -176,6 +176,7 @@ namespace { private: void BuildRankMap(Function &F); unsigned getRank(Value *V); + void canonicalizeOperands(Instruction *I); void ReassociateExpression(BinaryOperator *I); void RewriteExprTree(BinaryOperator *I, SmallVectorImpl &Ops); Value *OptimizeExpression(BinaryOperator *I, @@ -232,8 +233,8 @@ INITIALIZE_PASS(Reassociate, "reassociate", // Public interface to the Reassociate pass FunctionPass *llvm::createReassociatePass() { return new Reassociate(); } -/// isReassociableOp - Return true if V is an instruction of the specified -/// opcode and if it only has one use. +/// Return true if V is an instruction of the specified opcode and if it +/// only has one use. static BinaryOperator *isReassociableOp(Value *V, unsigned Opcode) { if (V->hasOneUse() && isa(V) && cast(V)->getOpcode() == Opcode && @@ -278,9 +279,11 @@ static bool isUnmovableInstruction(Instruction *I) { void Reassociate::BuildRankMap(Function &F) { unsigned i = 2; - // Assign distinct ranks to function arguments - for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I) + // Assign distinct ranks to function arguments. + for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I) { ValueRankMap[&*I] = ++i; + DEBUG(dbgs() << "Calculated Rank[" << I->getName() << "] = " << i << "\n"); + } ReversePostOrderTraversal RPOT(&F); for (ReversePostOrderTraversal::rpo_iterator I = RPOT.begin(), @@ -318,21 +321,35 @@ unsigned Reassociate::getRank(Value *V) { // If this is a not or neg instruction, do not count it for rank. This // assures us that X and ~X will have the same rank. - Type *Ty = V->getType(); - if ((!Ty->isIntegerTy() && !Ty->isFloatingPointTy()) || - (!BinaryOperator::isNot(I) && !BinaryOperator::isNeg(I) && - !BinaryOperator::isFNeg(I))) + if (!BinaryOperator::isNot(I) && !BinaryOperator::isNeg(I) && + !BinaryOperator::isFNeg(I)) ++Rank; - //DEBUG(dbgs() << "Calculated Rank[" << V->getName() << "] = " - // << Rank << "\n"); + DEBUG(dbgs() << "Calculated Rank[" << V->getName() << "] = " << Rank << "\n"); return ValueRankMap[I] = Rank; } +// Canonicalize constants to RHS. Otherwise, sort the operands by rank. +void Reassociate::canonicalizeOperands(Instruction *I) { + assert(isa(I) && "Expected binary operator."); + assert(I->isCommutative() && "Expected commutative operator."); + + Value *LHS = I->getOperand(0); + Value *RHS = I->getOperand(1); + unsigned LHSRank = getRank(LHS); + unsigned RHSRank = getRank(RHS); + + if (isa(RHS)) + return; + + if (isa(LHS) || RHSRank < LHSRank) + cast(I)->swapOperands(); +} + static BinaryOperator *CreateAdd(Value *S1, Value *S2, const Twine &Name, Instruction *InsertBefore, Value *FlagsOp) { - if (S1->getType()->isIntegerTy()) + if (S1->getType()->isIntOrIntVectorTy()) return BinaryOperator::CreateAdd(S1, S2, Name, InsertBefore); else { BinaryOperator *Res = @@ -344,7 +361,7 @@ static BinaryOperator *CreateAdd(Value *S1, Value *S2, const Twine &Name, static BinaryOperator *CreateMul(Value *S1, Value *S2, const Twine &Name, Instruction *InsertBefore, Value *FlagsOp) { - if (S1->getType()->isIntegerTy()) + if (S1->getType()->isIntOrIntVectorTy()) return BinaryOperator::CreateMul(S1, S2, Name, InsertBefore); else { BinaryOperator *Res = @@ -356,7 +373,7 @@ static BinaryOperator *CreateMul(Value *S1, Value *S2, const Twine &Name, static BinaryOperator *CreateNeg(Value *S1, const Twine &Name, Instruction *InsertBefore, Value *FlagsOp) { - if (S1->getType()->isIntegerTy()) + if (S1->getType()->isIntOrIntVectorTy()) return BinaryOperator::CreateNeg(S1, Name, InsertBefore); else { BinaryOperator *Res = BinaryOperator::CreateFNeg(S1, Name, InsertBefore); @@ -365,12 +382,11 @@ static BinaryOperator *CreateNeg(Value *S1, const Twine &Name, } } -/// LowerNegateToMultiply - Replace 0-X with X*-1. -/// +/// Replace 0-X with X*-1. static BinaryOperator *LowerNegateToMultiply(Instruction *Neg) { Type *Ty = Neg->getType(); - Constant *NegOne = Ty->isIntegerTy() ? ConstantInt::getAllOnesValue(Ty) - : ConstantFP::get(Ty, -1.0); + Constant *NegOne = Ty->isIntOrIntVectorTy() ? + ConstantInt::getAllOnesValue(Ty) : ConstantFP::get(Ty, -1.0); BinaryOperator *Res = CreateMul(Neg->getOperand(1), NegOne, "", Neg, Neg); Neg->setOperand(1, Constant::getNullValue(Ty)); // Drop use of op. @@ -380,8 +396,8 @@ static BinaryOperator *LowerNegateToMultiply(Instruction *Neg) { return Res; } -/// CarmichaelShift - Returns k such that lambda(2^Bitwidth) = 2^k, where lambda -/// is the Carmichael function. This means that x^(2^k) === 1 mod 2^Bitwidth for +/// Returns k such that lambda(2^Bitwidth) = 2^k, where lambda is the Carmichael +/// function. This means that x^(2^k) === 1 mod 2^Bitwidth for /// every odd x, i.e. x^(2^k) = 1 for every odd x in Bitwidth-bit arithmetic. /// Note that 0 <= k < Bitwidth, and if Bitwidth > 3 then x^(2^k) = 0 for every /// even x in Bitwidth-bit arithmetic. @@ -391,7 +407,7 @@ static unsigned CarmichaelShift(unsigned Bitwidth) { return Bitwidth - 2; } -/// IncorporateWeight - Add the extra weight 'RHS' to the existing weight 'LHS', +/// Add the extra weight 'RHS' to the existing weight 'LHS', /// reducing the combined weight using any special properties of the operation. /// The existing weight LHS represents the computation X op X op ... op X where /// X occurs LHS times. The combined weight represents X op X op ... op X with @@ -473,7 +489,7 @@ static void IncorporateWeight(APInt &LHS, const APInt &RHS, unsigned Opcode) { typedef std::pair RepeatedValue; -/// LinearizeExprTree - Given an associative binary expression, return the leaf +/// Given an associative binary expression, return the leaf /// nodes in Ops along with their weights (how many times the leaf occurs). The /// original expression is the same as /// (Ops[0].first op Ops[0].first op ... Ops[0].first) <- Ops[0].second times @@ -567,7 +583,7 @@ static bool LinearizeExprTree(BinaryOperator *I, // ways to get to it. SmallVector, 8> Worklist; // (Op, Weight) Worklist.push_back(std::make_pair(I, APInt(Bitwidth, 1))); - bool MadeChange = false; + bool Changed = false; // Leaves of the expression are values that either aren't the right kind of // operation (eg: a constant, or a multiply in an add tree), or are, but have @@ -604,7 +620,7 @@ static bool LinearizeExprTree(BinaryOperator *I, // If this is a binary operation of the right kind with only one use then // add its operands to the expression. if (BinaryOperator *BO = isReassociableOp(Op, Opcode)) { - assert(Visited.insert(Op) && "Not first visit!"); + assert(Visited.insert(Op).second && "Not first visit!"); DEBUG(dbgs() << "DIRECT ADD: " << *Op << " (" << Weight << ")\n"); Worklist.push_back(std::make_pair(BO, Weight)); continue; @@ -614,7 +630,7 @@ static bool LinearizeExprTree(BinaryOperator *I, LeafMap::iterator It = Leaves.find(Op); if (It == Leaves.end()) { // Not in the leaf map. Must be the first time we saw this operand. - assert(Visited.insert(Op) && "Not first visit!"); + assert(Visited.insert(Op).second && "Not first visit!"); if (!Op->hasOneUse()) { // This value has uses not accounted for by the expression, so it is // not safe to modify. Mark it as being a leaf. @@ -636,7 +652,7 @@ static bool LinearizeExprTree(BinaryOperator *I, // exactly one such use, drop this new use of the leaf. assert(!Op->hasOneUse() && "Only one use, but we got here twice!"); I->setOperand(OpIdx, UndefValue::get(I->getType())); - MadeChange = true; + Changed = true; // If the leaf is a binary operation of the right kind and we now see // that its multiple original uses were in fact all by nodes belonging @@ -680,7 +696,7 @@ static bool LinearizeExprTree(BinaryOperator *I, BO = LowerNegateToMultiply(BO); DEBUG(dbgs() << *BO << '\n'); Worklist.push_back(std::make_pair(BO, Weight)); - MadeChange = true; + Changed = true; continue; } @@ -720,11 +736,11 @@ static bool LinearizeExprTree(BinaryOperator *I, Ops.push_back(std::make_pair(Identity, APInt(Bitwidth, 1))); } - return MadeChange; + return Changed; } -// RewriteExprTree - Now that the operands for this expression tree are -// linearized and optimized, emit them in-order. +/// Now that the operands for this expression tree are +/// linearized and optimized, emit them in-order. void Reassociate::RewriteExprTree(BinaryOperator *I, SmallVectorImpl &Ops) { assert(Ops.size() > 1 && "Single values should be used directly!"); @@ -853,7 +869,7 @@ void Reassociate::RewriteExprTree(BinaryOperator *I, Constant *Undef = UndefValue::get(I->getType()); NewOp = BinaryOperator::Create(Instruction::BinaryOps(Opcode), Undef, Undef, "", I); - if (NewOp->getType()->isFloatingPointTy()) + if (NewOp->getType()->isFPOrFPVectorTy()) NewOp->setFastMathFlags(I->getFastMathFlags()); } else { NewOp = NodesToRewrite.pop_back_val(); @@ -893,15 +909,18 @@ void Reassociate::RewriteExprTree(BinaryOperator *I, RedoInsts.insert(NodesToRewrite[i]); } -/// NegateValue - Insert instructions before the instruction pointed to by BI, +/// Insert instructions before the instruction pointed to by BI, /// that computes the negative version of the value specified. The negative /// version of the value is returned, and BI is left pointing at the instruction /// that should be processed next by the reassociation pass. static Value *NegateValue(Value *V, Instruction *BI) { - if (ConstantFP *C = dyn_cast(V)) - return ConstantExpr::getFNeg(C); - if (Constant *C = dyn_cast(V)) + if (Constant *C = dyn_cast(V)) { + if (C->getType()->isFPOrFPVectorTy()) { + return ConstantExpr::getFNeg(C); + } return ConstantExpr::getNeg(C); + } + // We are trying to expose opportunity for reassociation. One of the things // that we want to do to achieve this is to push a negation as deep into an @@ -965,8 +984,7 @@ static Value *NegateValue(Value *V, Instruction *BI) { return CreateNeg(V, V->getName() + ".neg", BI, BI); } -/// ShouldBreakUpSubtract - Return true if we should break up this subtract of -/// X-Y into (X + -Y). +/// Return true if we should break up this subtract of X-Y into (X + -Y). static bool ShouldBreakUpSubtract(Instruction *Sub) { // If this is a negation, we can't split it up! if (BinaryOperator::isNeg(Sub) || BinaryOperator::isFNeg(Sub)) @@ -995,9 +1013,8 @@ static bool ShouldBreakUpSubtract(Instruction *Sub) { return false; } -/// BreakUpSubtract - If we have (X-Y), and if either X is an add, or if this is -/// only used by an add, transform this into (X+(0-Y)) to promote better -/// reassociation. +/// If we have (X-Y), and if either X is an add, or if this is only used by an +/// add, transform this into (X+(0-Y)) to promote better reassociation. static BinaryOperator *BreakUpSubtract(Instruction *Sub) { // Convert a subtract into an add and a neg instruction. This allows sub // instructions to be commuted with other add instructions. @@ -1019,9 +1036,8 @@ static BinaryOperator *BreakUpSubtract(Instruction *Sub) { return New; } -/// ConvertShiftToMul - If this is a shift of a reassociable multiply or is used -/// by one, change this into a multiply by a constant to assist with further -/// reassociation. +/// If this is a shift of a reassociable multiply or is used by one, change +/// this into a multiply by a constant to assist with further reassociation. static BinaryOperator *ConvertShiftToMul(Instruction *Shl) { Constant *MulCst = ConstantInt::get(Shl->getType(), 1); MulCst = ConstantExpr::getShl(MulCst, cast(Shl->getOperand(1))); @@ -1046,10 +1062,9 @@ static BinaryOperator *ConvertShiftToMul(Instruction *Shl) { return Mul; } -/// FindInOperandList - Scan backwards and forwards among values with the same -/// rank as element i to see if X exists. If X does not exist, return i. This -/// is useful when scanning for 'x' when we see '-x' because they both get the -/// same rank. +/// Scan backwards and forwards among values with the same rank as element i +/// to see if X exists. If X does not exist, return i. This is useful when +/// scanning for 'x' when we see '-x' because they both get the same rank. static unsigned FindInOperandList(SmallVectorImpl &Ops, unsigned i, Value *X) { unsigned XRank = Ops[i].Rank; @@ -1074,7 +1089,7 @@ static unsigned FindInOperandList(SmallVectorImpl &Ops, unsigned i, return i; } -/// EmitAddTreeOfValues - Emit a tree of add instructions, summing Ops together +/// Emit a tree of add instructions, summing Ops together /// and returning the result. Insert the tree before I. static Value *EmitAddTreeOfValues(Instruction *I, SmallVectorImpl &Ops){ @@ -1086,8 +1101,8 @@ static Value *EmitAddTreeOfValues(Instruction *I, return CreateAdd(V2, V1, "tmp", I, I); } -/// RemoveFactorFromExpression - If V is an expression tree that is a -/// multiplication sequence, and if this sequence contains a multiply by Factor, +/// If V is an expression tree that is a multiplication sequence, +/// and if this sequence contains a multiply by Factor, /// remove Factor from the tree and return the new tree. Value *Reassociate::RemoveFactorFromExpression(Value *V, Value *Factor) { BinaryOperator *BO = isReassociableOp(V, Instruction::Mul, Instruction::FMul); @@ -1159,8 +1174,8 @@ Value *Reassociate::RemoveFactorFromExpression(Value *V, Value *Factor) { return V; } -/// FindSingleUseMultiplyFactors - If V is a single-use multiply, recursively -/// add its operands as factors, otherwise add V to the list of factors. +/// If V is a single-use multiply, recursively add its operands as factors, +/// otherwise add V to the list of factors. /// /// Ops is the top-level list of add operands we're trying to factor. static void FindSingleUseMultiplyFactors(Value *V, @@ -1177,10 +1192,9 @@ static void FindSingleUseMultiplyFactors(Value *V, FindSingleUseMultiplyFactors(BO->getOperand(0), Factors, Ops); } -/// OptimizeAndOrXor - Optimize a series of operands to an 'and', 'or', or 'xor' -/// instruction. This optimizes based on identities. If it can be reduced to -/// a single Value, it is returned, otherwise the Ops list is mutated as -/// necessary. +/// Optimize a series of operands to an 'and', 'or', or 'xor' instruction. +/// This optimizes based on identities. If it can be reduced to a single Value, +/// it is returned, otherwise the Ops list is mutated as necessary. static Value *OptimizeAndOrXor(unsigned Opcode, SmallVectorImpl &Ops) { // Scan the operand lists looking for X and ~X pairs, along with X,X pairs. @@ -1470,7 +1484,7 @@ Value *Reassociate::OptimizeXor(Instruction *I, return nullptr; } -/// OptimizeAdd - Optimize a series of operands to an 'add' instruction. This +/// Optimize a series of operands to an 'add' instruction. This /// optimizes based on identities. If it can be reduced to a single Value, it /// is returned, otherwise the Ops list is mutated as necessary. Value *Reassociate::OptimizeAdd(Instruction *I, @@ -1493,13 +1507,13 @@ Value *Reassociate::OptimizeAdd(Instruction *I, ++NumFound; } while (i != Ops.size() && Ops[i].Op == TheOp); - DEBUG(errs() << "\nFACTORING [" << NumFound << "]: " << *TheOp << '\n'); + DEBUG(dbgs() << "\nFACTORING [" << NumFound << "]: " << *TheOp << '\n'); ++NumFactor; // Insert a new multiply. Type *Ty = TheOp->getType(); - Constant *C = Ty->isIntegerTy() ? ConstantInt::get(Ty, NumFound) - : ConstantFP::get(Ty, NumFound); + Constant *C = Ty->isIntOrIntVectorTy() ? + ConstantInt::get(Ty, NumFound) : ConstantFP::get(Ty, NumFound); Instruction *Mul = CreateMul(TheOp, C, "factor", I, I); // Now that we have inserted a multiply, optimize it. This allows us to @@ -1589,7 +1603,7 @@ Value *Reassociate::OptimizeAdd(Instruction *I, SmallPtrSet Duplicates; for (unsigned i = 0, e = Factors.size(); i != e; ++i) { Value *Factor = Factors[i]; - if (!Duplicates.insert(Factor)) + if (!Duplicates.insert(Factor).second) continue; unsigned Occ = ++FactorOccurrences[Factor]; @@ -1631,7 +1645,7 @@ Value *Reassociate::OptimizeAdd(Instruction *I, // If any factor occurred more than one time, we can pull it out. if (MaxOcc > 1) { - DEBUG(errs() << "\nFACTORING [" << MaxOcc << "]: " << *MaxOccVal << '\n'); + DEBUG(dbgs() << "\nFACTORING [" << MaxOcc << "]: " << *MaxOccVal << '\n'); ++NumFactor; // Create a new instruction that uses the MaxOccVal twice. If we don't do @@ -1639,7 +1653,7 @@ Value *Reassociate::OptimizeAdd(Instruction *I, // from an expression will drop a use of maxocc, and this can cause // RemoveFactorFromExpression on successive values to behave differently. Instruction *DummyInst = - I->getType()->isIntegerTy() + I->getType()->isIntOrIntVectorTy() ? BinaryOperator::CreateAdd(MaxOccVal, MaxOccVal) : BinaryOperator::CreateFAdd(MaxOccVal, MaxOccVal); @@ -1770,7 +1784,7 @@ static Value *buildMultiplyTree(IRBuilder<> &Builder, Value *LHS = Ops.pop_back_val(); do { - if (LHS->getType()->isIntegerTy()) + if (LHS->getType()->isIntOrIntVectorTy()) LHS = Builder.CreateMul(LHS, Ops.pop_back_val()); else LHS = Builder.CreateFMul(LHS, Ops.pop_back_val()); @@ -1923,8 +1937,7 @@ Value *Reassociate::OptimizeExpression(BinaryOperator *I, return nullptr; } -/// EraseInst - Zap the given instruction, adding interesting operands to the -/// work list. +/// Zap the given instruction, adding interesting operands to the work list. void Reassociate::EraseInst(Instruction *I) { assert(isInstructionTriviallyDead(I) && "Trivially dead instructions only!"); SmallVector Ops(I->op_begin(), I->op_end()); @@ -1940,7 +1953,7 @@ void Reassociate::EraseInst(Instruction *I) { // and add that since that's where optimization actually happens. unsigned Opcode = Op->getOpcode(); while (Op->hasOneUse() && Op->user_back()->getOpcode() == Opcode && - Visited.insert(Op)) + Visited.insert(Op).second) Op = Op->user_back(); RedoInsts.insert(Op); } @@ -1953,9 +1966,10 @@ Instruction *Reassociate::canonicalizeNegConstExpr(Instruction *I) { if (!I->hasOneUse() || I->getType()->isVectorTy()) return nullptr; - // Must be a mul instruction. + // Must be a mul, fmul, or fdiv instruction. unsigned Opcode = I->getOpcode(); - if (Opcode != Instruction::Mul && Opcode != Instruction::FMul) + if (Opcode != Instruction::Mul && Opcode != Instruction::FMul && + Opcode != Instruction::FDiv) return nullptr; // Must have at least one constant operand. @@ -1968,7 +1982,7 @@ Instruction *Reassociate::canonicalizeNegConstExpr(Instruction *I) { Constant *C = C0 ? C0 : C1; unsigned ConstIdx = C0 ? 0 : 1; if (auto *CI = dyn_cast(C)) { - if (!CI->isNegative()) + if (!CI->isNegative() || CI->isMinValue(true)) return nullptr; } else if (auto *CF = dyn_cast(C)) { if (!CF->isNegative()) @@ -2037,7 +2051,7 @@ Instruction *Reassociate::canonicalizeNegConstExpr(Instruction *I) { return NI; } -/// OptimizeInst - Inspect and optimize the given instruction. Note that erasing +/// Inspect and optimize the given instruction. Note that erasing /// instructions is not allowed. void Reassociate::OptimizeInst(Instruction *I) { // Only consider operations that we understand. @@ -2061,34 +2075,20 @@ void Reassociate::OptimizeInst(Instruction *I) { if (Instruction *Res = canonicalizeNegConstExpr(I)) I = Res; - // Commute floating point binary operators, to canonicalize the order of their - // operands. This can potentially expose more CSE opportunities, and makes - // writing other transformations simpler. - if (I->getType()->isFloatingPointTy() || I->getType()->isVectorTy()) { - - // FAdd and FMul can be commuted. - unsigned Opcode = I->getOpcode(); - if (Opcode == Instruction::FMul || Opcode == Instruction::FAdd) { - Value *LHS = I->getOperand(0); - Value *RHS = I->getOperand(1); - unsigned LHSRank = getRank(LHS); - unsigned RHSRank = getRank(RHS); - - // Sort the operands by rank. - if (RHSRank < LHSRank) { - I->setOperand(0, RHS); - I->setOperand(1, LHS); - } - } + // Commute binary operators, to canonicalize the order of their operands. + // This can potentially expose more CSE opportunities, and makes writing other + // transformations simpler. + if (I->isCommutative()) + canonicalizeOperands(I); - // FIXME: We should commute vector instructions as well. However, this - // requires further analysis to determine the effect on later passes. + // TODO: We should optimize vector Xor instructions, but they are + // currently unsupported. + if (I->getType()->isVectorTy() && I->getOpcode() == Instruction::Xor) + return; - // Don't try to optimize vector instructions or anything that doesn't have - // unsafe algebra. - if (I->getType()->isVectorTy() || !I->hasUnsafeAlgebra()) - return; - } + // Don't optimize floating point instructions that don't have unsafe algebra. + if (I->getType()->isFloatingPointTy() && !I->hasUnsafeAlgebra()) + return; // Do not reassociate boolean (i1) expressions. We want to preserve the // original order of evaluation for short-circuited comparisons that @@ -2162,9 +2162,6 @@ void Reassociate::OptimizeInst(Instruction *I) { } void Reassociate::ReassociateExpression(BinaryOperator *I) { - assert(!I->getType()->isVectorTy() && - "Reassociation of vector instructions is not supported."); - // First, walk the expression tree, linearizing the tree, collecting the // operand information. SmallVector Tree; @@ -2187,7 +2184,7 @@ void Reassociate::ReassociateExpression(BinaryOperator *I) { // the vector. std::stable_sort(Ops.begin(), Ops.end()); - // OptimizeExpression - Now that we have the expression tree in a convenient + // Now that we have the expression tree in a convenient // sorted form, optimize it globally if possible. if (Value *V = OptimizeExpression(I, Ops)) { if (V == I)