From 1a3150098c137181576dc3e0960f8cd4abe9da1f Mon Sep 17 00:00:00 2001 From: Shuxin Yang Date: Tue, 18 Dec 2012 23:10:12 +0000 Subject: [PATCH] rdar://12801297 InstCombine for unsafe floating-point add/sub. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170471 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../InstCombine/InstCombineAddSub.cpp | 715 ++++++++++++++++++ test/Transforms/InstCombine/fast-math.ll | 102 +++ 2 files changed, 817 insertions(+) diff --git a/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/lib/Transforms/InstCombine/InstCombineAddSub.cpp index 47223c3b358..bd642dea36b 100644 --- a/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ b/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -19,10 +19,715 @@ using namespace llvm; using namespace PatternMatch; +namespace { + + /// Class representing coefficient of floating-point addend. + /// This class needs to be highly efficient, which is especially true for + /// the constructor. As of I write this comment, the cost of the default + /// constructor is merely 4-byte-store-zero (Assuming compiler is able to + /// perform write-merging). + /// + class FAddendCoef { + public: + // The constructor has to initialize a APFloat, which is uncessary for + // most addends which have coefficient either 1 or -1. So, the constructor + // is expensive. In order to avoid the cost of the constructor, we should + // reuse some instances whenever possible. The pre-created instances + // FAddCombine::Add[0-5] embodies this idea. + // + FAddendCoef() : IsFp(false), BufHasFpVal(false), IntVal(0) {} + ~FAddendCoef(); + + void set(short C) { + assert(!insaneIntVal(C) && "Insane coefficient"); + IsFp = false; IntVal = C; + } + + void set(const APFloat& C); + + void negate(); + + bool isZero() const { return isInt() ? !IntVal : getFpVal().isZero(); } + Value *getValue(Type *) const; + + // If possible, don't define operator+/operator- etc because these + // operators inevitably call FAddendCoef's constructor which is not cheap. + void operator=(const FAddendCoef &A); + void operator+=(const FAddendCoef &A); + void operator-=(const FAddendCoef &A); + void operator*=(const FAddendCoef &S); + + bool isOne() const { return isInt() && IntVal == 1; } + bool isTwo() const { return isInt() && IntVal == 2; } + bool isMinusOne() const { return isInt() && IntVal == -1; } + bool isMinusTwo() const { return isInt() && IntVal == -2; } + + private: + bool insaneIntVal(int V) { return V > 4 || V < -4; } + APFloat *getFpValPtr(void) + { return reinterpret_cast(&FpValBuf[0]); } + + const APFloat &getFpVal(void) const { + assert(IsFp && BufHasFpVal && "Incorret state"); + return *reinterpret_cast(&FpValBuf[0]); + } + + APFloat &getFpVal(void) + { assert(IsFp && BufHasFpVal && "Incorret state"); return *getFpValPtr(); } + + bool isInt() const { return !IsFp; } + + private: + bool IsFp; + + // True iff FpValBuf contains an instance of APFloat. + bool BufHasFpVal; + + // The integer coefficient of an individual addend is either 1 or -1, + // and we try to simplify at most 4 addends from neighboring at most + // two instructions. So the range of falls in [-4, 4]. APInt + // is overkill of this end. + short IntVal; + + union { + char FpValBuf[sizeof(APFloat)]; + int dummy; // So this structure has at least 4-byte alignment. + }; + }; + + /// FAddend is used to represent floating-point addend. An addend is + /// represented as , where the V is a symbolic value, and C is a + /// constant coefficient. A constant addend is represented as . + /// + class FAddend { + public: + FAddend() { Val = 0; } + + Value *getSymVal (void) const { return Val; } + const FAddendCoef &getCoef(void) const { return Coeff; } + + bool isConstant() const { return Val == 0; } + bool isZero() const { return Coeff.isZero(); } + + void set(short Coefficient, Value *V) { Coeff.set(Coefficient), Val = V; } + void set(const APFloat& Coefficient, Value *V) + { Coeff.set(Coefficient); Val = V; } + void set(const ConstantFP* Coefficient, Value *V) + { Coeff.set(Coefficient->getValueAPF()); Val = V; } + + void negate() { Coeff.negate(); } + + /// Drill down the U-D chain one step to find the definition of V, and + /// try to break the definition into one or two addends. + static unsigned drillValueDownOneStep(Value* V, FAddend &A0, FAddend &A1); + + /// Similar to FAddend::drillDownOneStep() except that the value being + /// splitted is the addend itself. + unsigned drillAddendDownOneStep(FAddend &Addend0, FAddend &Addend1) const; + + void operator+=(const FAddend &T) { + assert((Val == T.Val) && "Symbolic-values disagree"); + Coeff += T.Coeff; + } + + private: + void Scale(const FAddendCoef& ScaleAmt) { Coeff *= ScaleAmt; } + + // This addend has the value of "Coeff * Val". + Value *Val; + FAddendCoef Coeff; + }; + + /// FAddCombine is the class for optimizing an unsafe fadd/fsub along + /// with its neighboring at most two instructions. + /// + class FAddCombine { + public: + FAddCombine(InstCombiner::BuilderTy *B) : Builder(B), Instr(0) {} + Value *simplify(Instruction *FAdd); + + private: + typedef SmallVector AddendVect; + + Value *simplifyFAdd(AddendVect& V, unsigned InstrQuota); + + /// Convert given addend to a Value + Value *createAddendVal(const FAddend &A, bool& NeedNeg); + + /// Return the number of instructions needed to emit the N-ary addition. + unsigned calcInstrNumber(const AddendVect& Vect); + Value *createFSub(Value *Opnd0, Value *Opnd1); + Value *createFAdd(Value *Opnd0, Value *Opnd1); + Value *createFMul(Value *Opnd0, Value *Opnd1); + Value *createFNeg(Value *V); + Value *createNaryFAdd(const AddendVect& Opnds, unsigned InstrQuota); + void createInstPostProc(Instruction *NewInst); + + InstCombiner::BuilderTy *Builder; + Instruction *Instr; + + private: + // Debugging stuff are clustered here. + #ifndef NDEBUG + unsigned CreateInstrNum; + void initCreateInstNum() { CreateInstrNum = 0; } + void incCreateInstNum() { CreateInstrNum++; } + #else + void initCreateInstNum() {} + void incCreateInstNum() {} + #endif + }; +} + +//===----------------------------------------------------------------------===// +// +// Implementation of +// {FAddendCoef, FAddend, FAddition, FAddCombine}. +// +//===----------------------------------------------------------------------===// +FAddendCoef::~FAddendCoef() { + if (BufHasFpVal) + getFpValPtr()->~APFloat(); +} + +void FAddendCoef::set(const APFloat& C) { + APFloat *P = getFpValPtr(); + + if (isInt()) { + // As the buffer is meanless byte stream, we cannot call + // APFloat::operator=(). + new(P) APFloat(C); + } else + *P = C; + + IsFp = BufHasFpVal = true; +} + +void FAddendCoef::operator=(const FAddendCoef& That) { + if (That.isInt()) + set(That.IntVal); + else + set(That.getFpVal()); +} + +void FAddendCoef::operator+=(const FAddendCoef &That) { + enum APFloat::roundingMode RndMode = APFloat::rmNearestTiesToEven; + if (isInt() == That.isInt()) { + if (isInt()) + IntVal += That.IntVal; + else + getFpVal().add(That.getFpVal(), RndMode); + return; + } + + if (isInt()) { + const APFloat &T = That.getFpVal(); + set(T); + getFpVal().add(APFloat(T.getSemantics(), IntVal), RndMode); + return; + } + + APFloat &T = getFpVal(); + T.add(APFloat(T.getSemantics(), That.IntVal), RndMode); +} + +void FAddendCoef::operator-=(const FAddendCoef &That) { + enum APFloat::roundingMode RndMode = APFloat::rmNearestTiesToEven; + if (isInt() == That.isInt()) { + if (isInt()) + IntVal -= That.IntVal; + else + getFpVal().subtract(That.getFpVal(), RndMode); + return; + } + + if (isInt()) { + const APFloat &T = That.getFpVal(); + set(T); + getFpVal().subtract(APFloat(T.getSemantics(), IntVal), RndMode); + return; + } + + APFloat &T = getFpVal(); + T.subtract(APFloat(T.getSemantics(), IntVal), RndMode); +} + +void FAddendCoef::operator*=(const FAddendCoef &That) { + if (That.isOne()) + return; + + if (That.isMinusOne()) { + negate(); + return; + } + + if (isInt() && That.isInt()) { + int Res = IntVal * (int)That.IntVal; + assert(!insaneIntVal(Res) && "Insane int value"); + IntVal = Res; + return; + } + + const fltSemantics &Semantic = + isInt() ? That.getFpVal().getSemantics() : getFpVal().getSemantics(); + + if (isInt()) + set(APFloat(Semantic, IntVal)); + APFloat &F0 = getFpVal(); + + if (That.isInt()) + F0.multiply(APFloat(Semantic, That.IntVal), APFloat::rmNearestTiesToEven); + else + F0.multiply(That.getFpVal(), APFloat::rmNearestTiesToEven); + + return; +} + +void FAddendCoef::negate() { + if (isInt()) + IntVal = 0 - IntVal; + else + getFpVal().changeSign(); +} + +Value *FAddendCoef::getValue(Type *Ty) const { + return isInt() ? + ConstantFP::get(Ty, float(IntVal)) : + ConstantFP::get(Ty->getContext(), getFpVal()); +} + +// The definition of Addends +// ========================================= +// A + B <1, A>, <1,B> +// A - B <1, A>, <1,B> +// 0 - B <-1, B> +// C * A, +// A + C <1, A> +// 0 +/- 0 <0, NULL> (corner case) +// +// Legend: A and B are not constant, C is constant +// +unsigned FAddend::drillValueDownOneStep + (Value *Val, FAddend &Addend0, FAddend &Addend1) { + Instruction *I = 0; + if (Val == 0 || !(I = dyn_cast(Val))) + return 0; + + unsigned Opcode = I->getOpcode(); + + if (Opcode == Instruction::FAdd || Opcode == Instruction::FSub) { + ConstantFP *C0, *C1; + Value *Opnd0 = I->getOperand(0); + Value *Opnd1 = I->getOperand(1); + if ((C0 = dyn_cast(Opnd0)) && C0->isZero()) + Opnd0 = 0; + + if ((C1 = dyn_cast(Opnd1)) && C1->isZero()) + Opnd1 = 0; + + if (Opnd0) { + if (!C0) + Addend0.set(1, Opnd0); + else + Addend0.set(C0, 0); + } + + if (Opnd1) { + FAddend &Addend = Opnd0 ? Addend1 : Addend0; + if (!C1) + Addend.set(1, Opnd1); + else + Addend.set(C1, 0); + if (Opcode == Instruction::FSub) + Addend.negate(); + } + + if (Opnd0 || Opnd1) + return Opnd0 && Opnd1 ? 2 : 1; + + // Both operands are zero. Weird! + Addend0.set(APFloat(C0->getValueAPF().getSemantics()), 0); + return 1; + } + + if (I->getOpcode() == Instruction::FMul) { + Value *V0 = I->getOperand(0); + Value *V1 = I->getOperand(1); + if (ConstantFP *C = dyn_cast(V0)) { + Addend0.set(C, V1); + return 1; + } + + if (ConstantFP *C = dyn_cast(V1)) { + Addend0.set(C, V0); + return 1; + } + } + + return 0; +} + +// Try to break *this* addend into two addends. e.g. Suppose this addend is +// <2.3, V>, and V = X + Y, by calling this function, we obtain two addends, +// i.e. <2.3, X> and <2.3, Y>. +// +unsigned FAddend::drillAddendDownOneStep + (FAddend &Addend0, FAddend &Addend1) const { + if (isConstant()) + return 0; + + unsigned BreakNum = FAddend::drillValueDownOneStep(Val, Addend0, Addend1); + if (!BreakNum || Coeff.isOne()) + return BreakNum; + + Addend0.Scale(Coeff); + + if (BreakNum == 2) + Addend1.Scale(Coeff); + + return BreakNum; +} + +Value *FAddCombine::simplify(Instruction *I) { + assert(I->hasUnsafeAlgebra() && "Should be in unsafe mode"); + + // Currently we are not able to handle vector type. + if (I->getType()->isVectorTy()) + return 0; + + assert((I->getOpcode() == Instruction::FAdd || + I->getOpcode() == Instruction::FSub) && "Expect add/sub"); + + // Save the instruction before calling other member-functions. + Instr = I; + + FAddend Opnd0, Opnd1, Opnd0_0, Opnd0_1, Opnd1_0, Opnd1_1; + + unsigned OpndNum = FAddend::drillValueDownOneStep(I, Opnd0, Opnd1); + + // Step 1: Expand the 1st addend into Opnd0_0 and Opnd0_1. + unsigned Opnd0_ExpNum = 0; + unsigned Opnd1_ExpNum = 0; + + if (!Opnd0.isConstant()) + Opnd0_ExpNum = Opnd0.drillAddendDownOneStep(Opnd0_0, Opnd0_1); + + // Step 2: Expand the 2nd addend into Opnd1_0 and Opnd1_1. + if (OpndNum == 2 && !Opnd1.isConstant()) + Opnd1_ExpNum = Opnd1.drillAddendDownOneStep(Opnd1_0, Opnd1_1); + + // Step 3: Try to optimize Opnd0_0 + Opnd0_1 + Opnd1_0 + Opnd1_1 + if (Opnd0_ExpNum && Opnd1_ExpNum) { + AddendVect AllOpnds; + AllOpnds.push_back(&Opnd0_0); + AllOpnds.push_back(&Opnd1_0); + if (Opnd0_ExpNum == 2) + AllOpnds.push_back(&Opnd0_1); + if (Opnd1_ExpNum == 2) + AllOpnds.push_back(&Opnd1_1); + + // Compute instruction quota. We should save at least one instruction. + unsigned InstQuota = 0; + + Value *V0 = I->getOperand(0); + Value *V1 = I->getOperand(1); + InstQuota = ((!isa(V0) && V0->hasOneUse()) && + (!isa(V1) && V1->hasOneUse())) ? 2 : 1; + + if (Value *R = simplifyFAdd(AllOpnds, InstQuota)) + return R; + } + + if (OpndNum != 2) { + // The input instruction is : "I=0.0 +/- V". If the "V" were able to be + // splitted into two addends, say "V = X - Y", the instruction would have + // been optimized into "I = Y - X" in the previous steps. + // + const FAddendCoef &CE = Opnd0.getCoef(); + return CE.isOne() ? Opnd0.getSymVal() : 0; + } + + // step 4: Try to optimize Opnd0 + Opnd1_0 [+ Opnd1_1] + if (Opnd1_ExpNum) { + AddendVect AllOpnds; + AllOpnds.push_back(&Opnd0); + AllOpnds.push_back(&Opnd1_0); + if (Opnd1_ExpNum == 2) + AllOpnds.push_back(&Opnd1_1); + + if (Value *R = simplifyFAdd(AllOpnds, 1)) + return R; + } + + // step 5: Try to optimize Opnd1 + Opnd0_0 [+ Opnd0_1] + if (Opnd0_ExpNum) { + AddendVect AllOpnds; + AllOpnds.push_back(&Opnd1); + AllOpnds.push_back(&Opnd0_0); + if (Opnd0_ExpNum == 2) + AllOpnds.push_back(&Opnd0_1); + + if (Value *R = simplifyFAdd(AllOpnds, 1)) + return R; + } + + return 0; +} + +Value *FAddCombine::simplifyFAdd(AddendVect& Addends, unsigned InstrQuota) { + + unsigned AddendNum = Addends.size(); + assert(AddendNum <= 4 && "Too many addends"); + + // For saving intermediate results; + unsigned NextTmpIdx = 0; + FAddend TmpResult[3]; + + // Points to the constant addend of the resulting simplified expression. + // If the resulting expr has constant-addend, this constant-addend is + // desirable to reside at the top of the resulting expression tree. Placing + // constant close to supper-expr(s) will potentially reveal some optimization + // opportunities in super-expr(s). + // + const FAddend *ConstAdd = 0; + + // Simplified addends are placed . + AddendVect SimpVect; + + // The outer loop works on one symbolic-value at a time. Suppose the input + // addends are : , , , , , ... + // The symbolic-values will be processed in this order: x, y, z. + // + for (unsigned SymIdx = 0; SymIdx < AddendNum; SymIdx++) { + + const FAddend *ThisAddend = Addends[SymIdx]; + if (!ThisAddend) { + // This addend was processed before. + continue; + } + + Value *Val = ThisAddend->getSymVal(); + unsigned StartIdx = SimpVect.size(); + SimpVect.push_back(ThisAddend); + + // The inner loop collects addends sharing same symbolic-value, and these + // addends will be later on folded into a single addend. Following above + // example, if the symbolic value "y" is being processed, the inner loop + // will collect two addends "" and "". These two addends will + // be later on folded into "". + // + for (unsigned SameSymIdx = SymIdx + 1; + SameSymIdx < AddendNum; SameSymIdx++) { + const FAddend *T = Addends[SameSymIdx]; + if (T && T->getSymVal() == Val) { + // Set null such that next iteration of the outer loop will not process + // this addend again. + Addends[SameSymIdx] = 0; + SimpVect.push_back(T); + } + } + + // If multiple addends share same symbolic value, fold them together. + if (StartIdx + 1 != SimpVect.size()) { + FAddend &R = TmpResult[NextTmpIdx ++]; + R = *SimpVect[StartIdx]; + for (unsigned Idx = StartIdx + 1; Idx < SimpVect.size(); Idx++) + R += *SimpVect[Idx]; + + // Pop all addends being folded and push the resulting folded addend. + SimpVect.resize(StartIdx); + if (Val != 0) { + if (!R.isZero()) { + SimpVect.push_back(&R); + } + } else { + // Don't push constant addend at this time. It will be the last element + // of . + ConstAdd = &R; + } + } + } + + assert((NextTmpIdx <= sizeof(TmpResult)/sizeof(TmpResult[0]) + 1) && + "out-of-bound access"); + + if (ConstAdd) + SimpVect.push_back(ConstAdd); + + Value *Result; + if (!SimpVect.empty()) + Result = createNaryFAdd(SimpVect, InstrQuota); + else { + // The addition is folded to 0.0. + Result = ConstantFP::get(Instr->getType(), 0.0); + } + + return Result; +} + +Value *FAddCombine::createNaryFAdd + (const AddendVect &Opnds, unsigned InstrQuota) { + assert(!Opnds.empty() && "Expect at least one addend"); + + // Step 1: Check if the # of instructions needed exceeds the quota. + // + unsigned InstrNeeded = calcInstrNumber(Opnds); + if (InstrNeeded > InstrQuota) + return 0; + + initCreateInstNum(); + + // step 2: Emit the N-ary addition. + // Note that at most three instructions are involved in Fadd-InstCombine: the + // addition in question, and at most two neighboring instructions. + // The resulting optimized addition should have at least one less instruction + // than the original addition expression tree. This implies that the resulting + // N-ary addition has at most two instructions, and we don't need to worry + // about tree-height when constructing the N-ary addition. + + Value *LastVal = 0; + bool LastValNeedNeg = false; + + // Iterate the addends, creating fadd/fsub using adjacent two addends. + for (AddendVect::const_iterator I = Opnds.begin(), E = Opnds.end(); + I != E; I++) { + bool NeedNeg; + Value *V = createAddendVal(**I, NeedNeg); + if (!LastVal) { + LastVal = V; + LastValNeedNeg = NeedNeg; + continue; + } + + if (LastValNeedNeg == NeedNeg) { + LastVal = createFAdd(LastVal, V); + continue; + } + + if (LastValNeedNeg) + LastVal = createFSub(V, LastVal); + else + LastVal = createFSub(LastVal, V); + + LastValNeedNeg = false; + } + + if (LastValNeedNeg) { + LastVal = createFNeg(LastVal); + } + + #ifndef NDEBUG + assert(CreateInstrNum == InstrNeeded && + "Inconsistent in instruction numbers"); + #endif + + return LastVal; +} + +Value *FAddCombine::createFSub + (Value *Opnd0, Value *Opnd1) { + Value *V = Builder->CreateFSub(Opnd0, Opnd1); + createInstPostProc(cast(V)); + return V; +} + +Value *FAddCombine::createFNeg(Value *V) { + Value *Zero = cast(ConstantFP::get(V->getType(), 0.0)); + return createFSub(Zero, V); +} + +Value *FAddCombine::createFAdd + (Value *Opnd0, Value *Opnd1) { + Value *V = Builder->CreateFAdd(Opnd0, Opnd1); + createInstPostProc(cast(V)); + return V; +} + +Value *FAddCombine::createFMul(Value *Opnd0, Value *Opnd1) { + Value *V = Builder->CreateFMul(Opnd0, Opnd1); + createInstPostProc(cast(V)); + return V; +} + +void FAddCombine::createInstPostProc(Instruction *NewInstr) { + NewInstr->setDebugLoc(Instr->getDebugLoc()); + + // Keep track of the number of instruction created. + incCreateInstNum(); + + // Propagate fast-math flags + NewInstr->setFastMathFlags(Instr->getFastMathFlags()); +} + +// Return the number of instruction needed to emit the N-ary addition. +// NOTE: Keep this function in sync with createAddendVal(). +unsigned FAddCombine::calcInstrNumber(const AddendVect &Opnds) { + unsigned OpndNum = Opnds.size(); + unsigned InstrNeeded = OpndNum - 1; + + // The number of addends in the form of "(-1)*x". + unsigned NegOpndNum = 0; + + // Adjust the number of instructions needed to emit the N-ary add. + for (AddendVect::const_iterator I = Opnds.begin(), E = Opnds.end(); + I != E; I++) { + const FAddend *Opnd = *I; + if (Opnd->isConstant()) + continue; + + const FAddendCoef &CE = Opnd->getCoef(); + if (CE.isMinusOne() || CE.isMinusTwo()) + NegOpndNum++; + + // Let the addend be "c * x". If "c == +/-1", the value of the addend + // is immediately available; otherwise, it needs exactly one instruction + // to evaluate the value. + if (!CE.isMinusOne() && !CE.isOne()) + InstrNeeded++; + } + if (NegOpndNum == OpndNum) + InstrNeeded++; + return InstrNeeded; +} + +// Input Addend Value NeedNeg(output) +// ================================================================ +// Constant C C false +// <+/-1, V> V coefficient is -1 +// <2/-2, V> "fadd V, V" coefficient is -2 +// "fmul V, C" false +// +// NOTE: Keep this function in sync with FAddCombine::calcInstrNumber. +Value *FAddCombine::createAddendVal + (const FAddend &Opnd, bool &NeedNeg) { + const FAddendCoef &Coeff = Opnd.getCoef(); + + if (Opnd.isConstant()) { + NeedNeg = false; + return Coeff.getValue(Instr->getType()); + } + + Value *OpndVal = Opnd.getSymVal(); + + if (Coeff.isMinusOne() || Coeff.isOne()) { + NeedNeg = Coeff.isMinusOne(); + return OpndVal; + } + + if (Coeff.isTwo() || Coeff.isMinusTwo()) { + NeedNeg = Coeff.isMinusTwo(); + return createFAdd(OpndVal, OpndVal); + } + + NeedNeg = false; + return createFMul(OpndVal, Coeff.getValue(Instr->getType())); +} + /// AddOne - Add one to a ConstantInt. static Constant *AddOne(Constant *C) { return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1)); } + /// SubOne - Subtract one from a ConstantInt. static Constant *SubOne(ConstantInt *C) { return ConstantInt::get(C->getContext(), C->getValue()-1); @@ -406,6 +1111,11 @@ Instruction *InstCombiner::visitFAdd(BinaryOperator &I) { } } + if (I.hasUnsafeAlgebra()) { + if (Value *V = FAddCombine(Builder).simplify(&I)) + return ReplaceInstUsesWith(I, V); + } + return Changed ? &I : 0; } @@ -649,5 +1359,10 @@ Instruction *InstCombiner::visitFSub(BinaryOperator &I) { if (Value *V = dyn_castFNegVal(Op1)) return BinaryOperator::CreateFAdd(Op0, V); + if (I.hasUnsafeAlgebra()) { + if (Value *V = FAddCombine(Builder).simplify(&I)) + return ReplaceInstUsesWith(I, V); + } + return 0; } diff --git a/test/Transforms/InstCombine/fast-math.ll b/test/Transforms/InstCombine/fast-math.ll index 0b87cd95d9c..f2365b31822 100644 --- a/test/Transforms/InstCombine/fast-math.ll +++ b/test/Transforms/InstCombine/fast-math.ll @@ -28,6 +28,108 @@ define float @fold2(float %a) { ret float %mul1 } +; C * f1 + f1 = (C+1) * f1 +define double @fold3(double %f1) { + %t1 = fmul fast double 2.000000e+00, %f1 + %t2 = fadd fast double %f1, %t1 + ret double %t2 +; CHECK: @fold3 +; CHECK: fmul fast double %f1, 3.000000e+00 +} + +; (C1 - X) + (C2 - Y) => (C1+C2) - (X + Y) +define float @fold4(float %f1, float %f2) { + %sub = fsub float 4.000000e+00, %f1 + %sub1 = fsub float 5.000000e+00, %f2 + %add = fadd fast float %sub, %sub1 + ret float %add +; CHECK: @fold4 +; CHECK: %1 = fadd fast float %f1, %f2 +; CHECK: fsub fast float 9.000000e+00, %1 +} + +; (X + C1) + C2 => X + (C1 + C2) +define float @fold5(float %f1, float %f2) { + %add = fadd float %f1, 4.000000e+00 + %add1 = fadd fast float %add, 5.000000e+00 + ret float %add1 +; CHECK: @fold5 +; CHECK: fadd float %f1, 9.000000e+00 +} + +; (X + X) + X => 3.0 * X +define float @fold6(float %f1) { + %t1 = fadd fast float %f1, %f1 + %t2 = fadd fast float %f1, %t1 + ret float %t2 +; CHECK: @fold6 +; CHECK: fmul fast float %f1, 3.000000e+00 +} + +; C1 * X + (X + X) = (C1 + 2) * X +define float @fold7(float %f1) { + %t1 = fmul fast float %f1, 5.000000e+00 + %t2 = fadd fast float %f1, %f1 + %t3 = fadd fast float %t1, %t2 + ret float %t3 +; CHECK: @fold7 +; CHECK: fmul fast float %f1, 7.000000e+00 +} + +; (X + X) + (X + X) => 4.0 * X +define float @fold8(float %f1) { + %t1 = fadd fast float %f1, %f1 + %t2 = fadd fast float %f1, %f1 + %t3 = fadd fast float %t1, %t2 + ret float %t3 +; CHECK: fold8 +; CHECK: fmul fast float %f1, 4.000000e+00 +} + +; X - (X + Y) => 0 - Y +define float @fold9(float %f1, float %f2) { + %t1 = fadd float %f1, %f2 + %t3 = fsub fast float %f1, %t1 + ret float %t3 + +; CHECK: @fold9 +; CHECK: fsub fast float 0.000000e+00, %f2 +} + +; Let C3 = C1 + C2. (f1 + C1) + (f2 + C2) => (f1 + f2) + C3 instead of +; "(f1 + C3) + f2" or "(f2 + C3) + f1". Placing constant-addend at the +; top of resulting simplified expression tree may potentially reveal some +; optimization opportunities in the super-expression trees. +; +define float @fold10(float %f1, float %f2) { + %t1 = fadd fast float 2.000000e+00, %f1 + %t2 = fsub fast float %f2, 3.000000e+00 + %t3 = fadd fast float %t1, %t2 + ret float %t3 +; CHECK: @fold10 +; CHECK: %t3 = fadd float %t2, -1.000000e+00 +; CHECK: ret float %t3 +} + +; once cause Crash/miscompilation +define float @fail1(float %f1, float %f2) { + %conv3 = fadd fast float %f1, -1.000000e+00 + %add = fadd fast float %conv3, %conv3 + %add2 = fadd fast float %add, %conv3 + ret float %add2 +; CHECK: @fail1 +; CHECK: ret +} + +define double @fail2(double %f1, double %f2) { + %t1 = fsub fast double %f1, %f2 + %t2 = fadd fast double %f1, %f2 + %t3 = fsub fast double %t1, %t2 + ret double %t3 +; CHECK: @fail2 +; CHECK: ret +} + ; rdar://12753946: x * cond ? 1.0 : 0.0 => cond ? x : 0.0 define double @select1(i32 %cond, double %x, double %y) { %tobool = icmp ne i32 %cond, 0 -- 2.34.1