[llvm-commits] [llvm] r170471 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineAddSub.cpp test/Transforms/InstCombine/fast-math.ll
Shuxin Yang
shuxin.llvm at gmail.com
Tue Dec 18 15:10:12 PST 2012
Author: shuxin_yang
Date: Tue Dec 18 17:10:12 2012
New Revision: 170471
URL: http://llvm.org/viewvc/llvm-project?rev=170471&view=rev
Log:
rdar://12801297
InstCombine for unsafe floating-point add/sub.
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
llvm/trunk/test/Transforms/InstCombine/fast-math.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp?rev=170471&r1=170470&r2=170471&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp Tue Dec 18 17:10:12 2012
@@ -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<APFloat*>(&FpValBuf[0]); }
+
+ const APFloat &getFpVal(void) const {
+ assert(IsFp && BufHasFpVal && "Incorret state");
+ return *reinterpret_cast<const APFloat*>(&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 <IntVal> 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 <C, V>, where the V is a symbolic value, and C is a
+ /// constant coefficient. A constant addend is represented as <C, 0>.
+ ///
+ 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<const FAddend*, 4> 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 <Val> Addends
+// =========================================
+// A + B <1, A>, <1,B>
+// A - B <1, A>, <1,B>
+// 0 - B <-1, B>
+// C * A, <C, A>
+// A + C <1, A> <C, NULL>
+// 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<Instruction>(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<ConstantFP>(Opnd0)) && C0->isZero())
+ Opnd0 = 0;
+
+ if ((C1 = dyn_cast<ConstantFP>(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<ConstantFP>(V0)) {
+ Addend0.set(C, V1);
+ return 1;
+ }
+
+ if (ConstantFP *C = dyn_cast<ConstantFP>(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<Constant>(V0) && V0->hasOneUse()) &&
+ (!isa<Constant>(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 <SimpVect>.
+ AddendVect SimpVect;
+
+ // The outer loop works on one symbolic-value at a time. Suppose the input
+ // addends are : <a1, x>, <b1, y>, <a2, x>, <c1, z>, <b2, y>, ...
+ // 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 "<b1,y>" and "<b2,Y>". These two addends will
+ // be later on folded into "<b1+b2, y>".
+ //
+ 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 <SimpVect>.
+ 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<Instruction>(V));
+ return V;
+}
+
+Value *FAddCombine::createFNeg(Value *V) {
+ Value *Zero = cast<Value>(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<Instruction>(V));
+ return V;
+}
+
+Value *FAddCombine::createFMul(Value *Opnd0, Value *Opnd1) {
+ Value *V = Builder->CreateFMul(Opnd0, Opnd1);
+ createInstPostProc(cast<Instruction>(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
+// <C, V> "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 @@
}
}
+ if (I.hasUnsafeAlgebra()) {
+ if (Value *V = FAddCombine(Builder).simplify(&I))
+ return ReplaceInstUsesWith(I, V);
+ }
+
return Changed ? &I : 0;
}
@@ -649,5 +1359,10 @@
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;
}
Modified: llvm/trunk/test/Transforms/InstCombine/fast-math.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/fast-math.ll?rev=170471&r1=170470&r2=170471&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/fast-math.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/fast-math.ll Tue Dec 18 17:10:12 2012
@@ -28,6 +28,108 @@
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
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