#include "InstCombine.h"
#include "llvm/Analysis/InstructionSimplify.h"
-#include "llvm/Target/TargetData.h"
+#include "llvm/IR/DataLayout.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/PatternMatch.h"
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.buffer[0]); }
+
+ const APFloat &getFpVal(void) const {
+ assert(IsFp && BufHasFpVal && "Incorret state");
+ return *reinterpret_cast<const APFloat*>(&FpValBuf.buffer[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;
+
+ AlignedCharArrayUnion<APFloat> FpValBuf;
+ };
+
+ /// 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);
static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
if (!V->hasOneUse() || !V->getType()->isIntegerTy())
return 0;
-
+
Instruction *I = dyn_cast<Instruction>(V);
if (I == 0) return 0;
-
+
if (I->getOpcode() == Instruction::Mul)
if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
return I->getOperand(0);
bool InstCombiner::WillNotOverflowSignedAdd(Value *LHS, Value *RHS) {
// There are different heuristics we can use for this. Here are some simple
// ones.
-
- // Add has the property that adding any two 2's complement numbers can only
+
+ // Add has the property that adding any two 2's complement numbers can only
// have one carry bit which can change a sign. As such, if LHS and RHS each
// have at least two sign bits, we know that the addition of the two values
// will sign extend fine.
if (ComputeNumSignBits(LHS) > 1 && ComputeNumSignBits(RHS) > 1)
return true;
-
-
+
+
// If one of the operands only has one non-zero bit, and if the other operand
// has a known-zero bit in a more significant place than it (not including the
// sign bit) the ripple may go up to and fill the zero, but won't change the
// sign. For example, (X & ~4) + 1.
-
+
// TODO: Implement.
-
+
return false;
}
const APInt &Val = CI->getValue();
if (Val.isSignBit())
return BinaryOperator::CreateXor(LHS, RHS);
-
+
// See if SimplifyDemandedBits can simplify this. This handles stuff like
// (X & 254)+1 -> (X&254)|1
if (SimplifyDemandedInstructionBits(I))
if (ZExtInst *ZI = dyn_cast<ZExtInst>(LHS))
if (ZI->getSrcTy()->isIntegerTy(1))
return SelectInst::Create(ZI->getOperand(0), AddOne(CI), CI);
-
+
Value *XorLHS = 0; ConstantInt *XorRHS = 0;
if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
uint32_t TySizeBits = I.getType()->getScalarSizeInBits();
else if (XorRHS->getValue().isPowerOf2())
ExtendAmt = TySizeBits - XorRHS->getValue().logBase2() - 1;
}
-
+
if (ExtendAmt) {
APInt Mask = APInt::getHighBitsSet(TySizeBits, ExtendAmt);
if (!MaskedValueIsZero(XorLHS, Mask))
ExtendAmt = 0;
}
-
+
if (ExtendAmt) {
Constant *ShAmt = ConstantInt::get(I.getType(), ExtendAmt);
Value *NewShl = Builder->CreateShl(XorLHS, ShAmt, "sext");
return BinaryOperator::CreateAShr(NewShl, ShAmt);
}
+
+ // If this is a xor that was canonicalized from a sub, turn it back into
+ // a sub and fuse this add with it.
+ if (LHS->hasOneUse() && (XorRHS->getValue()+1).isPowerOf2()) {
+ IntegerType *IT = cast<IntegerType>(I.getType());
+ APInt LHSKnownOne(IT->getBitWidth(), 0);
+ APInt LHSKnownZero(IT->getBitWidth(), 0);
+ ComputeMaskedBits(XorLHS, LHSKnownZero, LHSKnownOne);
+ if ((XorRHS->getValue() | LHSKnownZero).isAllOnesValue())
+ return BinaryOperator::CreateSub(ConstantExpr::getAdd(XorRHS, CI),
+ XorLHS);
+ }
}
}
return BinaryOperator::CreateXor(LHS, RHS);
// X + X --> X << 1
- if (LHS == RHS && I.getType()->isIntegerTy())
- return BinaryOperator::CreateShl(LHS, ConstantInt::get(I.getType(), 1));
+ if (LHS == RHS) {
+ BinaryOperator *New =
+ BinaryOperator::CreateShl(LHS, ConstantInt::get(I.getType(), 1));
+ New->setHasNoSignedWrap(I.hasNoSignedWrap());
+ New->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
+ return New;
+ }
// -A + B --> B - A
// -A + -B --> -(A + B)
if (Value *LHSV = dyn_castNegVal(LHS)) {
- if (Value *RHSV = dyn_castNegVal(RHS)) {
- Value *NewAdd = Builder->CreateAdd(LHSV, RHSV, "sum");
- return BinaryOperator::CreateNeg(NewAdd);
- }
-
+ if (!isa<Constant>(RHS))
+ if (Value *RHSV = dyn_castNegVal(RHS)) {
+ Value *NewAdd = Builder->CreateAdd(LHSV, RHSV, "sum");
+ return BinaryOperator::CreateNeg(NewAdd);
+ }
+
return BinaryOperator::CreateSub(RHS, LHSV);
}
return BinaryOperator::CreateMul(LHS, AddOne(C2));
// A+B --> A|B iff A and B have no bits set in common.
- if (const IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
- APInt Mask = APInt::getAllOnesValue(IT->getBitWidth());
+ if (IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
APInt LHSKnownOne(IT->getBitWidth(), 0);
APInt LHSKnownZero(IT->getBitWidth(), 0);
- ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne);
+ ComputeMaskedBits(LHS, LHSKnownZero, LHSKnownOne);
if (LHSKnownZero != 0) {
APInt RHSKnownOne(IT->getBitWidth(), 0);
APInt RHSKnownZero(IT->getBitWidth(), 0);
- ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne);
-
+ ComputeMaskedBits(RHS, RHSKnownZero, RHSKnownOne);
+
// No bits in common -> bitwise or.
if ((LHSKnownZero|RHSKnownZero).isAllOnesValue())
return BinaryOperator::CreateOr(LHS, RHS);
// See if all bits from the first bit set in the Add RHS up are included
// in the mask. First, get the rightmost bit.
const APInt &AddRHSV = CRHS->getValue();
-
+
// Form a mask of all bits from the lowest bit added through the top.
APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1));
if (match(FV, m_Zero()) && match(TV, m_Sub(m_Value(N), m_Specific(A))))
// Fold the add into the true select value.
return SelectInst::Create(SI->getCondition(), N, A);
-
+
if (match(TV, m_Zero()) && match(FV, m_Sub(m_Value(N), m_Specific(A))))
// Fold the add into the false select value.
return SelectInst::Create(SI->getCondition(), A, N);
if (SExtInst *LHSConv = dyn_cast<SExtInst>(LHS)) {
// (add (sext x), cst) --> (sext (add x, cst'))
if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
- Constant *CI =
+ Constant *CI =
ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType());
if (LHSConv->hasOneUse() &&
ConstantExpr::getSExt(CI, I.getType()) == RHSC &&
WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
// Insert the new, smaller add.
- Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
+ Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
CI, "addconv");
return new SExtInst(NewAdd, I.getType());
}
}
-
+
// (add (sext x), (sext y)) --> (sext (add int x, y))
if (SExtInst *RHSConv = dyn_cast<SExtInst>(RHS)) {
// Only do this if x/y have the same type, if at last one of them has a
WillNotOverflowSignedAdd(LHSConv->getOperand(0),
RHSConv->getOperand(0))) {
// Insert the new integer add.
- Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
+ Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
RHSConv->getOperand(0), "addconv");
return new SExtInst(NewAdd, I.getType());
}
}
}
+ // Check for (x & y) + (x ^ y)
+ {
+ Value *A = 0, *B = 0;
+ if (match(RHS, m_Xor(m_Value(A), m_Value(B))) &&
+ (match(LHS, m_And(m_Specific(A), m_Specific(B))) ||
+ match(LHS, m_And(m_Specific(B), m_Specific(A)))))
+ return BinaryOperator::CreateOr(A, B);
+
+ if (match(LHS, m_Xor(m_Value(A), m_Value(B))) &&
+ (match(RHS, m_And(m_Specific(A), m_Specific(B))) ||
+ match(RHS, m_And(m_Specific(B), m_Specific(A)))))
+ return BinaryOperator::CreateOr(A, B);
+ }
+
return Changed ? &I : 0;
}
bool Changed = SimplifyAssociativeOrCommutative(I);
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
- if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
- // X + 0 --> X
- if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
- if (CFP->isExactlyValue(ConstantFP::getNegativeZero
- (I.getType())->getValueAPF()))
- return ReplaceInstUsesWith(I, LHS);
- }
+ if (Value *V = SimplifyFAddInst(LHS, RHS, I.getFastMathFlags(), TD))
+ return ReplaceInstUsesWith(I, V);
- if (isa<PHINode>(LHS))
- if (Instruction *NV = FoldOpIntoPhi(I))
- return NV;
- }
+ if (isa<Constant>(RHS) && isa<PHINode>(LHS))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
// -A + B --> B - A
// -A + -B --> -(A + B)
if (Value *V = dyn_castFNegVal(RHS))
return BinaryOperator::CreateFSub(LHS, V);
- // Check for X+0.0. Simplify it to X if we know X is not -0.0.
- if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS))
- if (CFP->getValueAPF().isPosZero() && CannotBeNegativeZero(LHS))
- return ReplaceInstUsesWith(I, LHS);
-
// Check for (fadd double (sitofp x), y), see if we can merge this into an
// integer add followed by a promotion.
if (SIToFPInst *LHSConv = dyn_cast<SIToFPInst>(LHS)) {
// requires a constant pool load, and generally allows the add to be better
// instcombined.
if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) {
- Constant *CI =
+ Constant *CI =
ConstantExpr::getFPToSI(CFP, LHSConv->getOperand(0)->getType());
if (LHSConv->hasOneUse() &&
ConstantExpr::getSIToFP(CI, I.getType()) == CFP &&
return new SIToFPInst(NewAdd, I.getType());
}
}
-
+
// (fadd double (sitofp x), (sitofp y)) --> (sitofp (add int x, y))
if (SIToFPInst *RHSConv = dyn_cast<SIToFPInst>(RHS)) {
// Only do this if x/y have the same type, if at last one of them has a
WillNotOverflowSignedAdd(LHSConv->getOperand(0),
RHSConv->getOperand(0))) {
// Insert the new integer add.
- Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
+ Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
RHSConv->getOperand(0),"addconv");
return new SIToFPInst(NewAdd, I.getType());
}
}
}
-
- return Changed ? &I : 0;
-}
-
-
-/// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
-/// code necessary to compute the offset from the base pointer (without adding
-/// in the base pointer). Return the result as a signed integer of intptr size.
-Value *InstCombiner::EmitGEPOffset(User *GEP) {
- TargetData &TD = *getTargetData();
- gep_type_iterator GTI = gep_type_begin(GEP);
- const Type *IntPtrTy = TD.getIntPtrType(GEP->getContext());
- Value *Result = Constant::getNullValue(IntPtrTy);
- // If the GEP is inbounds, we know that none of the addressing operations will
- // overflow in an unsigned sense.
- bool isInBounds = cast<GEPOperator>(GEP)->isInBounds();
-
- // Build a mask for high order bits.
- unsigned IntPtrWidth = TD.getPointerSizeInBits();
- uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
-
- for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e;
- ++i, ++GTI) {
- Value *Op = *i;
- uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()) & PtrSizeMask;
- if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) {
- if (OpC->isZero()) continue;
-
- // Handle a struct index, which adds its field offset to the pointer.
- if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
- Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
-
- if (Size)
- Result = Builder->CreateAdd(Result, ConstantInt::get(IntPtrTy, Size),
- GEP->getName()+".offs");
- continue;
- }
-
- Constant *Scale = ConstantInt::get(IntPtrTy, Size);
- Constant *OC =
- ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
- Scale = ConstantExpr::getMul(OC, Scale, isInBounds/*NUW*/);
- // Emit an add instruction.
- Result = Builder->CreateAdd(Result, Scale, GEP->getName()+".offs");
- continue;
- }
- // Convert to correct type.
- if (Op->getType() != IntPtrTy)
- Op = Builder->CreateIntCast(Op, IntPtrTy, true, Op->getName()+".c");
- if (Size != 1) {
- // We'll let instcombine(mul) convert this to a shl if possible.
- Op = Builder->CreateMul(Op, ConstantInt::get(IntPtrTy, Size),
- GEP->getName()+".idx", isInBounds /*NUW*/);
- }
-
- // Emit an add instruction.
- Result = Builder->CreateAdd(Op, Result, GEP->getName()+".offs");
+ if (I.hasUnsafeAlgebra()) {
+ if (Value *V = FAddCombine(Builder).simplify(&I))
+ return ReplaceInstUsesWith(I, V);
}
- return Result;
-}
-
+ return Changed ? &I : 0;
+}
/// Optimize pointer differences into the same array into a size. Consider:
/// operands to the ptrtoint instructions for the LHS/RHS of the subtract.
///
Value *InstCombiner::OptimizePointerDifference(Value *LHS, Value *RHS,
- const Type *Ty) {
+ Type *Ty) {
assert(TD && "Must have target data info for this");
-
+
// If LHS is a gep based on RHS or RHS is a gep based on LHS, we can optimize
// this.
bool Swapped = false;
- GetElementPtrInst *GEP = 0;
- ConstantExpr *CstGEP = 0;
-
- // TODO: Could also optimize &A[i] - &A[j] -> "i-j", and "&A.foo[i] - &A.foo".
+ GEPOperator *GEP1 = 0, *GEP2 = 0;
+
// For now we require one side to be the base pointer "A" or a constant
- // expression derived from it.
- if (GetElementPtrInst *LHSGEP = dyn_cast<GetElementPtrInst>(LHS)) {
+ // GEP derived from it.
+ if (GEPOperator *LHSGEP = dyn_cast<GEPOperator>(LHS)) {
// (gep X, ...) - X
if (LHSGEP->getOperand(0) == RHS) {
- GEP = LHSGEP;
+ GEP1 = LHSGEP;
Swapped = false;
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(RHS)) {
- // (gep X, ...) - (ce_gep X, ...)
- if (CE->getOpcode() == Instruction::GetElementPtr &&
- LHSGEP->getOperand(0) == CE->getOperand(0)) {
- CstGEP = CE;
- GEP = LHSGEP;
+ } else if (GEPOperator *RHSGEP = dyn_cast<GEPOperator>(RHS)) {
+ // (gep X, ...) - (gep X, ...)
+ if (LHSGEP->getOperand(0)->stripPointerCasts() ==
+ RHSGEP->getOperand(0)->stripPointerCasts()) {
+ GEP2 = RHSGEP;
+ GEP1 = LHSGEP;
Swapped = false;
}
}
}
-
- if (GetElementPtrInst *RHSGEP = dyn_cast<GetElementPtrInst>(RHS)) {
+
+ if (GEPOperator *RHSGEP = dyn_cast<GEPOperator>(RHS)) {
// X - (gep X, ...)
if (RHSGEP->getOperand(0) == LHS) {
- GEP = RHSGEP;
+ GEP1 = RHSGEP;
Swapped = true;
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(LHS)) {
- // (ce_gep X, ...) - (gep X, ...)
- if (CE->getOpcode() == Instruction::GetElementPtr &&
- RHSGEP->getOperand(0) == CE->getOperand(0)) {
- CstGEP = CE;
- GEP = RHSGEP;
+ } else if (GEPOperator *LHSGEP = dyn_cast<GEPOperator>(LHS)) {
+ // (gep X, ...) - (gep X, ...)
+ if (RHSGEP->getOperand(0)->stripPointerCasts() ==
+ LHSGEP->getOperand(0)->stripPointerCasts()) {
+ GEP2 = LHSGEP;
+ GEP1 = RHSGEP;
Swapped = true;
}
}
}
-
- if (GEP == 0)
+
+ // Avoid duplicating the arithmetic if GEP2 has non-constant indices and
+ // multiple users.
+ if (GEP1 == 0 ||
+ (GEP2 != 0 && !GEP2->hasAllConstantIndices() && !GEP2->hasOneUse()))
return 0;
-
+
// Emit the offset of the GEP and an intptr_t.
- Value *Result = EmitGEPOffset(GEP);
-
+ Value *Result = EmitGEPOffset(GEP1);
+
// If we had a constant expression GEP on the other side offsetting the
// pointer, subtract it from the offset we have.
- if (CstGEP) {
- Value *CstOffset = EmitGEPOffset(CstGEP);
- Result = Builder->CreateSub(Result, CstOffset);
+ if (GEP2) {
+ Value *Offset = EmitGEPOffset(GEP2);
+ Result = Builder->CreateSub(Result, Offset);
}
-
// If we have p - gep(p, ...) then we have to negate the result.
if (Swapped)
// Replace (-1 - A) with (~A).
if (match(Op0, m_AllOnes()))
return BinaryOperator::CreateNot(Op1);
-
+
if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
// C - ~X == X + (1+C)
Value *X = 0;
if (Instruction *R = FoldOpIntoSelect(I, SI))
return R;
- // C - zext(bool) -> bool ? C - 1 : C
- if (ZExtInst *ZI = dyn_cast<ZExtInst>(Op1))
- if (ZI->getSrcTy()->isIntegerTy(1))
- return SelectInst::Create(ZI->getOperand(0), SubOne(C), C);
-
// C-(X+C2) --> (C-C2)-X
ConstantInt *C2;
if (match(Op1, m_Add(m_Value(X), m_ConstantInt(C2))))
return BinaryOperator::CreateSub(ConstantExpr::getSub(C, C2), X);
+
+ if (SimplifyDemandedInstructionBits(I))
+ return &I;
}
-
+
{ Value *Y;
// X-(X+Y) == -Y X-(Y+X) == -Y
if (match(Op1, m_Add(m_Specific(Op0), m_Value(Y))) ||
match(Op1, m_Add(m_Value(Y), m_Specific(Op0))))
return BinaryOperator::CreateNeg(Y);
-
+
// (X-Y)-X == -Y
if (match(Op0, m_Sub(m_Specific(Op1), m_Value(Y))))
return BinaryOperator::CreateNeg(Y);
}
-
+
if (Op1->hasOneUse()) {
Value *X = 0, *Y = 0, *Z = 0;
Constant *C = 0;
match(Op1, m_And(m_Specific(Op0), m_Value(Y))))
return BinaryOperator::CreateAnd(Op0,
Builder->CreateNot(Y, Y->getName() + ".not"));
-
+
// 0 - (X sdiv C) -> (X sdiv -C)
if (match(Op1, m_SDiv(m_Value(X), m_Constant(C))) &&
match(Op0, m_Zero()))
C = ConstantExpr::getSub(One, ConstantExpr::getShl(One, CI));
return BinaryOperator::CreateMul(Op0, C);
}
-
+
// X - A*-B -> X + A*B
// X - -A*B -> X + A*B
Value *A, *B;
if (match(Op1, m_Mul(m_Value(A), m_Neg(m_Value(B)))) ||
match(Op1, m_Mul(m_Neg(m_Value(A)), m_Value(B))))
return BinaryOperator::CreateAdd(Op0, Builder->CreateMul(A, B));
-
+
// X - A*CI -> X + A*-CI
// X - CI*A -> X + A*-CI
if (match(Op1, m_Mul(m_Value(A), m_ConstantInt(CI))) ||
if (X == dyn_castFoldableMul(Op1, C2))
return BinaryOperator::CreateMul(X, ConstantExpr::getSub(C1, C2));
}
-
+
// Optimize pointer differences into the same array into a size. Consider:
// &A[10] - &A[0]: we should compile this to "10".
if (TD) {
match(Op1, m_PtrToInt(m_Value(RHSOp))))
if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
return ReplaceInstUsesWith(I, Res);
-
+
// trunc(p)-trunc(q) -> trunc(p-q)
if (match(Op0, m_Trunc(m_PtrToInt(m_Value(LHSOp)))) &&
match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp)))))
if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
return ReplaceInstUsesWith(I, Res);
}
-
+
return 0;
}
Instruction *InstCombiner::visitFSub(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+ if (Value *V = SimplifyFSubInst(Op0, Op1, I.getFastMathFlags(), TD))
+ return ReplaceInstUsesWith(I, V);
+
// If this is a 'B = x-(-A)', change to B = x+A...
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;
}
projects / oota-llvm.git / blobdiff