1 //===- InstCombineAddSub.cpp ------------------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the visit functions for add, fadd, sub, and fsub.
12 //===----------------------------------------------------------------------===//
14 #include "InstCombineInternal.h"
15 #include "llvm/ADT/STLExtras.h"
16 #include "llvm/Analysis/InstructionSimplify.h"
17 #include "llvm/IR/DataLayout.h"
18 #include "llvm/IR/GetElementPtrTypeIterator.h"
19 #include "llvm/IR/PatternMatch.h"
20 #include "llvm/Support/KnownBits.h"
23 using namespace PatternMatch;
25 #define DEBUG_TYPE "instcombine"
29 /// Class representing coefficient of floating-point addend.
30 /// This class needs to be highly efficient, which is especially true for
31 /// the constructor. As of I write this comment, the cost of the default
32 /// constructor is merely 4-byte-store-zero (Assuming compiler is able to
33 /// perform write-merging).
37 // The constructor has to initialize a APFloat, which is unnecessary for
38 // most addends which have coefficient either 1 or -1. So, the constructor
39 // is expensive. In order to avoid the cost of the constructor, we should
40 // reuse some instances whenever possible. The pre-created instances
41 // FAddCombine::Add[0-5] embodies this idea.
43 FAddendCoef() : IsFp(false), BufHasFpVal(false), IntVal(0) {}
47 assert(!insaneIntVal(C) && "Insane coefficient");
48 IsFp = false; IntVal = C;
51 void set(const APFloat& C);
55 bool isZero() const { return isInt() ? !IntVal : getFpVal().isZero(); }
56 Value *getValue(Type *) const;
58 // If possible, don't define operator+/operator- etc because these
59 // operators inevitably call FAddendCoef's constructor which is not cheap.
60 void operator=(const FAddendCoef &A);
61 void operator+=(const FAddendCoef &A);
62 void operator*=(const FAddendCoef &S);
64 bool isOne() const { return isInt() && IntVal == 1; }
65 bool isTwo() const { return isInt() && IntVal == 2; }
66 bool isMinusOne() const { return isInt() && IntVal == -1; }
67 bool isMinusTwo() const { return isInt() && IntVal == -2; }
70 bool insaneIntVal(int V) { return V > 4 || V < -4; }
71 APFloat *getFpValPtr()
72 { return reinterpret_cast<APFloat*>(&FpValBuf.buffer[0]); }
73 const APFloat *getFpValPtr() const
74 { return reinterpret_cast<const APFloat*>(&FpValBuf.buffer[0]); }
76 const APFloat &getFpVal() const {
77 assert(IsFp && BufHasFpVal && "Incorret state");
78 return *getFpValPtr();
82 assert(IsFp && BufHasFpVal && "Incorret state");
83 return *getFpValPtr();
86 bool isInt() const { return !IsFp; }
88 // If the coefficient is represented by an integer, promote it to a
90 void convertToFpType(const fltSemantics &Sem);
92 // Construct an APFloat from a signed integer.
93 // TODO: We should get rid of this function when APFloat can be constructed
94 // from an *SIGNED* integer.
95 APFloat createAPFloatFromInt(const fltSemantics &Sem, int Val);
100 // True iff FpValBuf contains an instance of APFloat.
103 // The integer coefficient of an individual addend is either 1 or -1,
104 // and we try to simplify at most 4 addends from neighboring at most
105 // two instructions. So the range of <IntVal> falls in [-4, 4]. APInt
106 // is overkill of this end.
109 AlignedCharArrayUnion<APFloat> FpValBuf;
112 /// FAddend is used to represent floating-point addend. An addend is
113 /// represented as <C, V>, where the V is a symbolic value, and C is a
114 /// constant coefficient. A constant addend is represented as <C, 0>.
118 FAddend() : Val(nullptr) {}
120 Value *getSymVal() const { return Val; }
121 const FAddendCoef &getCoef() const { return Coeff; }
123 bool isConstant() const { return Val == nullptr; }
124 bool isZero() const { return Coeff.isZero(); }
126 void set(short Coefficient, Value *V) {
127 Coeff.set(Coefficient);
130 void set(const APFloat &Coefficient, Value *V) {
131 Coeff.set(Coefficient);
134 void set(const ConstantFP *Coefficient, Value *V) {
135 Coeff.set(Coefficient->getValueAPF());
139 void negate() { Coeff.negate(); }
141 /// Drill down the U-D chain one step to find the definition of V, and
142 /// try to break the definition into one or two addends.
143 static unsigned drillValueDownOneStep(Value* V, FAddend &A0, FAddend &A1);
145 /// Similar to FAddend::drillDownOneStep() except that the value being
146 /// splitted is the addend itself.
147 unsigned drillAddendDownOneStep(FAddend &Addend0, FAddend &Addend1) const;
149 void operator+=(const FAddend &T) {
150 assert((Val == T.Val) && "Symbolic-values disagree");
155 void Scale(const FAddendCoef& ScaleAmt) { Coeff *= ScaleAmt; }
157 // This addend has the value of "Coeff * Val".
162 /// FAddCombine is the class for optimizing an unsafe fadd/fsub along
163 /// with its neighboring at most two instructions.
167 FAddCombine(InstCombiner::BuilderTy *B) : Builder(B), Instr(nullptr) {}
168 Value *simplify(Instruction *FAdd);
171 typedef SmallVector<const FAddend*, 4> AddendVect;
173 Value *simplifyFAdd(AddendVect& V, unsigned InstrQuota);
175 Value *performFactorization(Instruction *I);
177 /// Convert given addend to a Value
178 Value *createAddendVal(const FAddend &A, bool& NeedNeg);
180 /// Return the number of instructions needed to emit the N-ary addition.
181 unsigned calcInstrNumber(const AddendVect& Vect);
182 Value *createFSub(Value *Opnd0, Value *Opnd1);
183 Value *createFAdd(Value *Opnd0, Value *Opnd1);
184 Value *createFMul(Value *Opnd0, Value *Opnd1);
185 Value *createFDiv(Value *Opnd0, Value *Opnd1);
186 Value *createFNeg(Value *V);
187 Value *createNaryFAdd(const AddendVect& Opnds, unsigned InstrQuota);
188 void createInstPostProc(Instruction *NewInst, bool NoNumber = false);
190 InstCombiner::BuilderTy *Builder;
193 // Debugging stuff are clustered here.
195 unsigned CreateInstrNum;
196 void initCreateInstNum() { CreateInstrNum = 0; }
197 void incCreateInstNum() { CreateInstrNum++; }
199 void initCreateInstNum() {}
200 void incCreateInstNum() {}
204 } // anonymous namespace
206 //===----------------------------------------------------------------------===//
209 // {FAddendCoef, FAddend, FAddition, FAddCombine}.
211 //===----------------------------------------------------------------------===//
212 FAddendCoef::~FAddendCoef() {
214 getFpValPtr()->~APFloat();
217 void FAddendCoef::set(const APFloat& C) {
218 APFloat *P = getFpValPtr();
221 // As the buffer is meanless byte stream, we cannot call
222 // APFloat::operator=().
227 IsFp = BufHasFpVal = true;
230 void FAddendCoef::convertToFpType(const fltSemantics &Sem) {
234 APFloat *P = getFpValPtr();
236 new(P) APFloat(Sem, IntVal);
238 new(P) APFloat(Sem, 0 - IntVal);
241 IsFp = BufHasFpVal = true;
244 APFloat FAddendCoef::createAPFloatFromInt(const fltSemantics &Sem, int Val) {
246 return APFloat(Sem, Val);
248 APFloat T(Sem, 0 - Val);
254 void FAddendCoef::operator=(const FAddendCoef &That) {
258 set(That.getFpVal());
261 void FAddendCoef::operator+=(const FAddendCoef &That) {
262 enum APFloat::roundingMode RndMode = APFloat::rmNearestTiesToEven;
263 if (isInt() == That.isInt()) {
265 IntVal += That.IntVal;
267 getFpVal().add(That.getFpVal(), RndMode);
272 const APFloat &T = That.getFpVal();
273 convertToFpType(T.getSemantics());
274 getFpVal().add(T, RndMode);
278 APFloat &T = getFpVal();
279 T.add(createAPFloatFromInt(T.getSemantics(), That.IntVal), RndMode);
282 void FAddendCoef::operator*=(const FAddendCoef &That) {
286 if (That.isMinusOne()) {
291 if (isInt() && That.isInt()) {
292 int Res = IntVal * (int)That.IntVal;
293 assert(!insaneIntVal(Res) && "Insane int value");
298 const fltSemantics &Semantic =
299 isInt() ? That.getFpVal().getSemantics() : getFpVal().getSemantics();
302 convertToFpType(Semantic);
303 APFloat &F0 = getFpVal();
306 F0.multiply(createAPFloatFromInt(Semantic, That.IntVal),
307 APFloat::rmNearestTiesToEven);
309 F0.multiply(That.getFpVal(), APFloat::rmNearestTiesToEven);
312 void FAddendCoef::negate() {
316 getFpVal().changeSign();
319 Value *FAddendCoef::getValue(Type *Ty) const {
321 ConstantFP::get(Ty, float(IntVal)) :
322 ConstantFP::get(Ty->getContext(), getFpVal());
325 // The definition of <Val> Addends
326 // =========================================
327 // A + B <1, A>, <1,B>
328 // A - B <1, A>, <1,B>
331 // A + C <1, A> <C, NULL>
332 // 0 +/- 0 <0, NULL> (corner case)
334 // Legend: A and B are not constant, C is constant
336 unsigned FAddend::drillValueDownOneStep
337 (Value *Val, FAddend &Addend0, FAddend &Addend1) {
338 Instruction *I = nullptr;
339 if (!Val || !(I = dyn_cast<Instruction>(Val)))
342 unsigned Opcode = I->getOpcode();
344 if (Opcode == Instruction::FAdd || Opcode == Instruction::FSub) {
346 Value *Opnd0 = I->getOperand(0);
347 Value *Opnd1 = I->getOperand(1);
348 if ((C0 = dyn_cast<ConstantFP>(Opnd0)) && C0->isZero())
351 if ((C1 = dyn_cast<ConstantFP>(Opnd1)) && C1->isZero())
356 Addend0.set(1, Opnd0);
358 Addend0.set(C0, nullptr);
362 FAddend &Addend = Opnd0 ? Addend1 : Addend0;
364 Addend.set(1, Opnd1);
366 Addend.set(C1, nullptr);
367 if (Opcode == Instruction::FSub)
372 return Opnd0 && Opnd1 ? 2 : 1;
374 // Both operands are zero. Weird!
375 Addend0.set(APFloat(C0->getValueAPF().getSemantics()), nullptr);
379 if (I->getOpcode() == Instruction::FMul) {
380 Value *V0 = I->getOperand(0);
381 Value *V1 = I->getOperand(1);
382 if (ConstantFP *C = dyn_cast<ConstantFP>(V0)) {
387 if (ConstantFP *C = dyn_cast<ConstantFP>(V1)) {
396 // Try to break *this* addend into two addends. e.g. Suppose this addend is
397 // <2.3, V>, and V = X + Y, by calling this function, we obtain two addends,
398 // i.e. <2.3, X> and <2.3, Y>.
400 unsigned FAddend::drillAddendDownOneStep
401 (FAddend &Addend0, FAddend &Addend1) const {
405 unsigned BreakNum = FAddend::drillValueDownOneStep(Val, Addend0, Addend1);
406 if (!BreakNum || Coeff.isOne())
409 Addend0.Scale(Coeff);
412 Addend1.Scale(Coeff);
417 // Try to perform following optimization on the input instruction I. Return the
418 // simplified expression if was successful; otherwise, return 0.
420 // Instruction "I" is Simplified into
421 // -------------------------------------------------------
422 // (x * y) +/- (x * z) x * (y +/- z)
423 // (y / x) +/- (z / x) (y +/- z) / x
425 Value *FAddCombine::performFactorization(Instruction *I) {
426 assert((I->getOpcode() == Instruction::FAdd ||
427 I->getOpcode() == Instruction::FSub) && "Expect add/sub");
429 Instruction *I0 = dyn_cast<Instruction>(I->getOperand(0));
430 Instruction *I1 = dyn_cast<Instruction>(I->getOperand(1));
432 if (!I0 || !I1 || I0->getOpcode() != I1->getOpcode())
436 if (I0->getOpcode() == Instruction::FMul)
438 else if (I0->getOpcode() != Instruction::FDiv)
441 Value *Opnd0_0 = I0->getOperand(0);
442 Value *Opnd0_1 = I0->getOperand(1);
443 Value *Opnd1_0 = I1->getOperand(0);
444 Value *Opnd1_1 = I1->getOperand(1);
446 // Input Instr I Factor AddSub0 AddSub1
447 // ----------------------------------------------
448 // (x*y) +/- (x*z) x y z
449 // (y/x) +/- (z/x) x y z
451 Value *Factor = nullptr;
452 Value *AddSub0 = nullptr, *AddSub1 = nullptr;
455 if (Opnd0_0 == Opnd1_0 || Opnd0_0 == Opnd1_1)
457 else if (Opnd0_1 == Opnd1_0 || Opnd0_1 == Opnd1_1)
461 AddSub0 = (Factor == Opnd0_0) ? Opnd0_1 : Opnd0_0;
462 AddSub1 = (Factor == Opnd1_0) ? Opnd1_1 : Opnd1_0;
464 } else if (Opnd0_1 == Opnd1_1) {
474 Flags.setUnsafeAlgebra();
475 if (I0) Flags &= I->getFastMathFlags();
476 if (I1) Flags &= I->getFastMathFlags();
478 // Create expression "NewAddSub = AddSub0 +/- AddsSub1"
479 Value *NewAddSub = (I->getOpcode() == Instruction::FAdd) ?
480 createFAdd(AddSub0, AddSub1) :
481 createFSub(AddSub0, AddSub1);
482 if (ConstantFP *CFP = dyn_cast<ConstantFP>(NewAddSub)) {
483 const APFloat &F = CFP->getValueAPF();
486 } else if (Instruction *II = dyn_cast<Instruction>(NewAddSub))
487 II->setFastMathFlags(Flags);
490 Value *RI = createFMul(Factor, NewAddSub);
491 if (Instruction *II = dyn_cast<Instruction>(RI))
492 II->setFastMathFlags(Flags);
496 Value *RI = createFDiv(NewAddSub, Factor);
497 if (Instruction *II = dyn_cast<Instruction>(RI))
498 II->setFastMathFlags(Flags);
502 Value *FAddCombine::simplify(Instruction *I) {
503 assert(I->hasUnsafeAlgebra() && "Should be in unsafe mode");
505 // Currently we are not able to handle vector type.
506 if (I->getType()->isVectorTy())
509 assert((I->getOpcode() == Instruction::FAdd ||
510 I->getOpcode() == Instruction::FSub) && "Expect add/sub");
512 // Save the instruction before calling other member-functions.
515 FAddend Opnd0, Opnd1, Opnd0_0, Opnd0_1, Opnd1_0, Opnd1_1;
517 unsigned OpndNum = FAddend::drillValueDownOneStep(I, Opnd0, Opnd1);
519 // Step 1: Expand the 1st addend into Opnd0_0 and Opnd0_1.
520 unsigned Opnd0_ExpNum = 0;
521 unsigned Opnd1_ExpNum = 0;
523 if (!Opnd0.isConstant())
524 Opnd0_ExpNum = Opnd0.drillAddendDownOneStep(Opnd0_0, Opnd0_1);
526 // Step 2: Expand the 2nd addend into Opnd1_0 and Opnd1_1.
527 if (OpndNum == 2 && !Opnd1.isConstant())
528 Opnd1_ExpNum = Opnd1.drillAddendDownOneStep(Opnd1_0, Opnd1_1);
530 // Step 3: Try to optimize Opnd0_0 + Opnd0_1 + Opnd1_0 + Opnd1_1
531 if (Opnd0_ExpNum && Opnd1_ExpNum) {
533 AllOpnds.push_back(&Opnd0_0);
534 AllOpnds.push_back(&Opnd1_0);
535 if (Opnd0_ExpNum == 2)
536 AllOpnds.push_back(&Opnd0_1);
537 if (Opnd1_ExpNum == 2)
538 AllOpnds.push_back(&Opnd1_1);
540 // Compute instruction quota. We should save at least one instruction.
541 unsigned InstQuota = 0;
543 Value *V0 = I->getOperand(0);
544 Value *V1 = I->getOperand(1);
545 InstQuota = ((!isa<Constant>(V0) && V0->hasOneUse()) &&
546 (!isa<Constant>(V1) && V1->hasOneUse())) ? 2 : 1;
548 if (Value *R = simplifyFAdd(AllOpnds, InstQuota))
553 // The input instruction is : "I=0.0 +/- V". If the "V" were able to be
554 // splitted into two addends, say "V = X - Y", the instruction would have
555 // been optimized into "I = Y - X" in the previous steps.
557 const FAddendCoef &CE = Opnd0.getCoef();
558 return CE.isOne() ? Opnd0.getSymVal() : nullptr;
561 // step 4: Try to optimize Opnd0 + Opnd1_0 [+ Opnd1_1]
564 AllOpnds.push_back(&Opnd0);
565 AllOpnds.push_back(&Opnd1_0);
566 if (Opnd1_ExpNum == 2)
567 AllOpnds.push_back(&Opnd1_1);
569 if (Value *R = simplifyFAdd(AllOpnds, 1))
573 // step 5: Try to optimize Opnd1 + Opnd0_0 [+ Opnd0_1]
576 AllOpnds.push_back(&Opnd1);
577 AllOpnds.push_back(&Opnd0_0);
578 if (Opnd0_ExpNum == 2)
579 AllOpnds.push_back(&Opnd0_1);
581 if (Value *R = simplifyFAdd(AllOpnds, 1))
585 // step 6: Try factorization as the last resort,
586 return performFactorization(I);
589 Value *FAddCombine::simplifyFAdd(AddendVect& Addends, unsigned InstrQuota) {
590 unsigned AddendNum = Addends.size();
591 assert(AddendNum <= 4 && "Too many addends");
593 // For saving intermediate results;
594 unsigned NextTmpIdx = 0;
595 FAddend TmpResult[3];
597 // Points to the constant addend of the resulting simplified expression.
598 // If the resulting expr has constant-addend, this constant-addend is
599 // desirable to reside at the top of the resulting expression tree. Placing
600 // constant close to supper-expr(s) will potentially reveal some optimization
601 // opportunities in super-expr(s).
603 const FAddend *ConstAdd = nullptr;
605 // Simplified addends are placed <SimpVect>.
608 // The outer loop works on one symbolic-value at a time. Suppose the input
609 // addends are : <a1, x>, <b1, y>, <a2, x>, <c1, z>, <b2, y>, ...
610 // The symbolic-values will be processed in this order: x, y, z.
612 for (unsigned SymIdx = 0; SymIdx < AddendNum; SymIdx++) {
614 const FAddend *ThisAddend = Addends[SymIdx];
616 // This addend was processed before.
620 Value *Val = ThisAddend->getSymVal();
621 unsigned StartIdx = SimpVect.size();
622 SimpVect.push_back(ThisAddend);
624 // The inner loop collects addends sharing same symbolic-value, and these
625 // addends will be later on folded into a single addend. Following above
626 // example, if the symbolic value "y" is being processed, the inner loop
627 // will collect two addends "<b1,y>" and "<b2,Y>". These two addends will
628 // be later on folded into "<b1+b2, y>".
630 for (unsigned SameSymIdx = SymIdx + 1;
631 SameSymIdx < AddendNum; SameSymIdx++) {
632 const FAddend *T = Addends[SameSymIdx];
633 if (T && T->getSymVal() == Val) {
634 // Set null such that next iteration of the outer loop will not process
635 // this addend again.
636 Addends[SameSymIdx] = nullptr;
637 SimpVect.push_back(T);
641 // If multiple addends share same symbolic value, fold them together.
642 if (StartIdx + 1 != SimpVect.size()) {
643 FAddend &R = TmpResult[NextTmpIdx ++];
644 R = *SimpVect[StartIdx];
645 for (unsigned Idx = StartIdx + 1; Idx < SimpVect.size(); Idx++)
648 // Pop all addends being folded and push the resulting folded addend.
649 SimpVect.resize(StartIdx);
652 SimpVect.push_back(&R);
655 // Don't push constant addend at this time. It will be the last element
662 assert((NextTmpIdx <= array_lengthof(TmpResult) + 1) &&
663 "out-of-bound access");
666 SimpVect.push_back(ConstAdd);
669 if (!SimpVect.empty())
670 Result = createNaryFAdd(SimpVect, InstrQuota);
672 // The addition is folded to 0.0.
673 Result = ConstantFP::get(Instr->getType(), 0.0);
679 Value *FAddCombine::createNaryFAdd
680 (const AddendVect &Opnds, unsigned InstrQuota) {
681 assert(!Opnds.empty() && "Expect at least one addend");
683 // Step 1: Check if the # of instructions needed exceeds the quota.
685 unsigned InstrNeeded = calcInstrNumber(Opnds);
686 if (InstrNeeded > InstrQuota)
691 // step 2: Emit the N-ary addition.
692 // Note that at most three instructions are involved in Fadd-InstCombine: the
693 // addition in question, and at most two neighboring instructions.
694 // The resulting optimized addition should have at least one less instruction
695 // than the original addition expression tree. This implies that the resulting
696 // N-ary addition has at most two instructions, and we don't need to worry
697 // about tree-height when constructing the N-ary addition.
699 Value *LastVal = nullptr;
700 bool LastValNeedNeg = false;
702 // Iterate the addends, creating fadd/fsub using adjacent two addends.
703 for (const FAddend *Opnd : Opnds) {
705 Value *V = createAddendVal(*Opnd, NeedNeg);
708 LastValNeedNeg = NeedNeg;
712 if (LastValNeedNeg == NeedNeg) {
713 LastVal = createFAdd(LastVal, V);
718 LastVal = createFSub(V, LastVal);
720 LastVal = createFSub(LastVal, V);
722 LastValNeedNeg = false;
725 if (LastValNeedNeg) {
726 LastVal = createFNeg(LastVal);
730 assert(CreateInstrNum == InstrNeeded &&
731 "Inconsistent in instruction numbers");
737 Value *FAddCombine::createFSub(Value *Opnd0, Value *Opnd1) {
738 Value *V = Builder->CreateFSub(Opnd0, Opnd1);
739 if (Instruction *I = dyn_cast<Instruction>(V))
740 createInstPostProc(I);
744 Value *FAddCombine::createFNeg(Value *V) {
745 Value *Zero = cast<Value>(ConstantFP::getZeroValueForNegation(V->getType()));
746 Value *NewV = createFSub(Zero, V);
747 if (Instruction *I = dyn_cast<Instruction>(NewV))
748 createInstPostProc(I, true); // fneg's don't receive instruction numbers.
752 Value *FAddCombine::createFAdd(Value *Opnd0, Value *Opnd1) {
753 Value *V = Builder->CreateFAdd(Opnd0, Opnd1);
754 if (Instruction *I = dyn_cast<Instruction>(V))
755 createInstPostProc(I);
759 Value *FAddCombine::createFMul(Value *Opnd0, Value *Opnd1) {
760 Value *V = Builder->CreateFMul(Opnd0, Opnd1);
761 if (Instruction *I = dyn_cast<Instruction>(V))
762 createInstPostProc(I);
766 Value *FAddCombine::createFDiv(Value *Opnd0, Value *Opnd1) {
767 Value *V = Builder->CreateFDiv(Opnd0, Opnd1);
768 if (Instruction *I = dyn_cast<Instruction>(V))
769 createInstPostProc(I);
773 void FAddCombine::createInstPostProc(Instruction *NewInstr, bool NoNumber) {
774 NewInstr->setDebugLoc(Instr->getDebugLoc());
776 // Keep track of the number of instruction created.
780 // Propagate fast-math flags
781 NewInstr->setFastMathFlags(Instr->getFastMathFlags());
784 // Return the number of instruction needed to emit the N-ary addition.
785 // NOTE: Keep this function in sync with createAddendVal().
786 unsigned FAddCombine::calcInstrNumber(const AddendVect &Opnds) {
787 unsigned OpndNum = Opnds.size();
788 unsigned InstrNeeded = OpndNum - 1;
790 // The number of addends in the form of "(-1)*x".
791 unsigned NegOpndNum = 0;
793 // Adjust the number of instructions needed to emit the N-ary add.
794 for (const FAddend *Opnd : Opnds) {
795 if (Opnd->isConstant())
798 // The constant check above is really for a few special constant
800 if (isa<UndefValue>(Opnd->getSymVal()))
803 const FAddendCoef &CE = Opnd->getCoef();
804 if (CE.isMinusOne() || CE.isMinusTwo())
807 // Let the addend be "c * x". If "c == +/-1", the value of the addend
808 // is immediately available; otherwise, it needs exactly one instruction
809 // to evaluate the value.
810 if (!CE.isMinusOne() && !CE.isOne())
813 if (NegOpndNum == OpndNum)
818 // Input Addend Value NeedNeg(output)
819 // ================================================================
820 // Constant C C false
821 // <+/-1, V> V coefficient is -1
822 // <2/-2, V> "fadd V, V" coefficient is -2
823 // <C, V> "fmul V, C" false
825 // NOTE: Keep this function in sync with FAddCombine::calcInstrNumber.
826 Value *FAddCombine::createAddendVal(const FAddend &Opnd, bool &NeedNeg) {
827 const FAddendCoef &Coeff = Opnd.getCoef();
829 if (Opnd.isConstant()) {
831 return Coeff.getValue(Instr->getType());
834 Value *OpndVal = Opnd.getSymVal();
836 if (Coeff.isMinusOne() || Coeff.isOne()) {
837 NeedNeg = Coeff.isMinusOne();
841 if (Coeff.isTwo() || Coeff.isMinusTwo()) {
842 NeedNeg = Coeff.isMinusTwo();
843 return createFAdd(OpndVal, OpndVal);
847 return createFMul(OpndVal, Coeff.getValue(Instr->getType()));
850 /// \brief Return true if we can prove that:
851 /// (sub LHS, RHS) === (sub nsw LHS, RHS)
852 /// This basically requires proving that the add in the original type would not
853 /// overflow to change the sign bit or have a carry out.
854 /// TODO: Handle this for Vectors.
855 bool InstCombiner::willNotOverflowSignedSub(const Value *LHS,
857 const Instruction &CxtI) const {
858 // If LHS and RHS each have at least two sign bits, the subtraction
860 if (ComputeNumSignBits(LHS, 0, &CxtI) > 1 &&
861 ComputeNumSignBits(RHS, 0, &CxtI) > 1)
864 KnownBits LHSKnown = computeKnownBits(LHS, 0, &CxtI);
866 KnownBits RHSKnown = computeKnownBits(RHS, 0, &CxtI);
868 // Subtraction of two 2's complement numbers having identical signs will
870 if ((LHSKnown.isNegative() && RHSKnown.isNegative()) ||
871 (LHSKnown.isNonNegative() && RHSKnown.isNonNegative()))
874 // TODO: implement logic similar to checkRippleForAdd
878 /// \brief Return true if we can prove that:
879 /// (sub LHS, RHS) === (sub nuw LHS, RHS)
880 bool InstCombiner::willNotOverflowUnsignedSub(const Value *LHS,
882 const Instruction &CxtI) const {
883 // If the LHS is negative and the RHS is non-negative, no unsigned wrap.
884 KnownBits LHSKnown = computeKnownBits(LHS, /*Depth=*/0, &CxtI);
885 KnownBits RHSKnown = computeKnownBits(RHS, /*Depth=*/0, &CxtI);
886 if (LHSKnown.isNegative() && RHSKnown.isNonNegative())
892 // Checks if any operand is negative and we can convert add to sub.
893 // This function checks for following negative patterns
894 // ADD(XOR(OR(Z, NOT(C)), C)), 1) == NEG(AND(Z, C))
895 // ADD(XOR(AND(Z, C), C), 1) == NEG(OR(Z, ~C))
896 // XOR(AND(Z, C), (C + 1)) == NEG(OR(Z, ~C)) if C is even
897 static Value *checkForNegativeOperand(BinaryOperator &I,
898 InstCombiner::BuilderTy *Builder) {
899 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
901 // This function creates 2 instructions to replace ADD, we need at least one
902 // of LHS or RHS to have one use to ensure benefit in transform.
903 if (!LHS->hasOneUse() && !RHS->hasOneUse())
906 Value *X = nullptr, *Y = nullptr, *Z = nullptr;
907 const APInt *C1 = nullptr, *C2 = nullptr;
909 // if ONE is on other side, swap
910 if (match(RHS, m_Add(m_Value(X), m_One())))
913 if (match(LHS, m_Add(m_Value(X), m_One()))) {
914 // if XOR on other side, swap
915 if (match(RHS, m_Xor(m_Value(Y), m_APInt(C1))))
918 if (match(X, m_Xor(m_Value(Y), m_APInt(C1)))) {
919 // X = XOR(Y, C1), Y = OR(Z, C2), C2 = NOT(C1) ==> X == NOT(AND(Z, C1))
920 // ADD(ADD(X, 1), RHS) == ADD(X, ADD(RHS, 1)) == SUB(RHS, AND(Z, C1))
921 if (match(Y, m_Or(m_Value(Z), m_APInt(C2))) && (*C2 == ~(*C1))) {
922 Value *NewAnd = Builder->CreateAnd(Z, *C1);
923 return Builder->CreateSub(RHS, NewAnd, "sub");
924 } else if (match(Y, m_And(m_Value(Z), m_APInt(C2))) && (*C1 == *C2)) {
925 // X = XOR(Y, C1), Y = AND(Z, C2), C2 == C1 ==> X == NOT(OR(Z, ~C1))
926 // ADD(ADD(X, 1), RHS) == ADD(X, ADD(RHS, 1)) == SUB(RHS, OR(Z, ~C1))
927 Value *NewOr = Builder->CreateOr(Z, ~(*C1));
928 return Builder->CreateSub(RHS, NewOr, "sub");
933 // Restore LHS and RHS
934 LHS = I.getOperand(0);
935 RHS = I.getOperand(1);
937 // if XOR is on other side, swap
938 if (match(RHS, m_Xor(m_Value(Y), m_APInt(C1))))
942 // LHS = XOR(Y, C1), Y = AND(Z, C2), C1 == (C2 + 1) => LHS == NEG(OR(Z, ~C2))
943 // ADD(LHS, RHS) == SUB(RHS, OR(Z, ~C2))
944 if (match(LHS, m_Xor(m_Value(Y), m_APInt(C1))))
945 if (C1->countTrailingZeros() == 0)
946 if (match(Y, m_And(m_Value(Z), m_APInt(C2))) && *C1 == (*C2 + 1)) {
947 Value *NewOr = Builder->CreateOr(Z, ~(*C2));
948 return Builder->CreateSub(RHS, NewOr, "sub");
953 static Instruction *foldAddWithConstant(BinaryOperator &Add,
954 InstCombiner::BuilderTy &Builder) {
955 Value *Op0 = Add.getOperand(0), *Op1 = Add.getOperand(1);
957 if (!match(Op1, m_APInt(C)))
960 if (C->isSignMask()) {
961 // If wrapping is not allowed, then the addition must set the sign bit:
962 // X + (signmask) --> X | signmask
963 if (Add.hasNoSignedWrap() || Add.hasNoUnsignedWrap())
964 return BinaryOperator::CreateOr(Op0, Op1);
966 // If wrapping is allowed, then the addition flips the sign bit of LHS:
967 // X + (signmask) --> X ^ signmask
968 return BinaryOperator::CreateXor(Op0, Op1);
973 Type *Ty = Add.getType();
975 // Is this add the last step in a convoluted sext?
976 // add(zext(xor i16 X, -32768), -32768) --> sext X
977 if (match(Op0, m_ZExt(m_Xor(m_Value(X), m_APInt(C2)))) &&
978 C2->isMinSignedValue() && C2->sext(Ty->getScalarSizeInBits()) == *C)
979 return CastInst::Create(Instruction::SExt, X, Ty);
981 // (add (zext (add nuw X, C2)), C) --> (zext (add nuw X, C2 + C))
982 // FIXME: This should check hasOneUse to not increase the instruction count?
983 if (C->isNegative() &&
984 match(Op0, m_ZExt(m_NUWAdd(m_Value(X), m_APInt(C2)))) &&
985 C->sge(-C2->sext(C->getBitWidth()))) {
987 ConstantInt::get(X->getType(), *C2 + C->trunc(C2->getBitWidth()));
988 return new ZExtInst(Builder.CreateNUWAdd(X, NewC), Ty);
991 // Shifts and add used to flip and mask off the low bit:
992 // add (ashr (shl i32 X, 31), 31), 1 --> and (not X), 1
994 if (*C == 1 && match(Op0, m_OneUse(m_AShr(m_Shl(m_Value(X), m_APInt(C2)),
996 C2 == C3 && *C2 == Ty->getScalarSizeInBits() - 1) {
997 Value *NotX = Builder.CreateNot(X);
998 return BinaryOperator::CreateAnd(NotX, ConstantInt::get(Ty, 1));
1004 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
1005 bool Changed = SimplifyAssociativeOrCommutative(I);
1006 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
1008 if (Value *V = SimplifyVectorOp(I))
1009 return replaceInstUsesWith(I, V);
1011 if (Value *V = SimplifyAddInst(LHS, RHS, I.hasNoSignedWrap(),
1012 I.hasNoUnsignedWrap(), SQ))
1013 return replaceInstUsesWith(I, V);
1015 // (A*B)+(A*C) -> A*(B+C) etc
1016 if (Value *V = SimplifyUsingDistributiveLaws(I))
1017 return replaceInstUsesWith(I, V);
1019 if (Instruction *X = foldAddWithConstant(I, *Builder))
1022 // FIXME: This should be moved into the above helper function to allow these
1023 // transforms for splat vectors.
1024 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
1025 // zext(bool) + C -> bool ? C + 1 : C
1026 if (ZExtInst *ZI = dyn_cast<ZExtInst>(LHS))
1027 if (ZI->getSrcTy()->isIntegerTy(1))
1028 return SelectInst::Create(ZI->getOperand(0), AddOne(CI), CI);
1030 Value *XorLHS = nullptr; ConstantInt *XorRHS = nullptr;
1031 if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
1032 uint32_t TySizeBits = I.getType()->getScalarSizeInBits();
1033 const APInt &RHSVal = CI->getValue();
1034 unsigned ExtendAmt = 0;
1035 // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
1036 // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
1037 if (XorRHS->getValue() == -RHSVal) {
1038 if (RHSVal.isPowerOf2())
1039 ExtendAmt = TySizeBits - RHSVal.logBase2() - 1;
1040 else if (XorRHS->getValue().isPowerOf2())
1041 ExtendAmt = TySizeBits - XorRHS->getValue().logBase2() - 1;
1045 APInt Mask = APInt::getHighBitsSet(TySizeBits, ExtendAmt);
1046 if (!MaskedValueIsZero(XorLHS, Mask, 0, &I))
1051 Constant *ShAmt = ConstantInt::get(I.getType(), ExtendAmt);
1052 Value *NewShl = Builder->CreateShl(XorLHS, ShAmt, "sext");
1053 return BinaryOperator::CreateAShr(NewShl, ShAmt);
1056 // If this is a xor that was canonicalized from a sub, turn it back into
1057 // a sub and fuse this add with it.
1058 if (LHS->hasOneUse() && (XorRHS->getValue()+1).isPowerOf2()) {
1059 KnownBits LHSKnown = computeKnownBits(XorLHS, 0, &I);
1060 if ((XorRHS->getValue() | LHSKnown.Zero).isAllOnesValue())
1061 return BinaryOperator::CreateSub(ConstantExpr::getAdd(XorRHS, CI),
1064 // (X + signmask) + C could have gotten canonicalized to (X^signmask) + C,
1065 // transform them into (X + (signmask ^ C))
1066 if (XorRHS->getValue().isSignMask())
1067 return BinaryOperator::CreateAdd(XorLHS,
1068 ConstantExpr::getXor(XorRHS, CI));
1072 if (isa<Constant>(RHS))
1073 if (Instruction *NV = foldOpWithConstantIntoOperand(I))
1076 if (I.getType()->getScalarType()->isIntegerTy(1))
1077 return BinaryOperator::CreateXor(LHS, RHS);
1081 BinaryOperator *New =
1082 BinaryOperator::CreateShl(LHS, ConstantInt::get(I.getType(), 1));
1083 New->setHasNoSignedWrap(I.hasNoSignedWrap());
1084 New->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
1089 // -A + -B --> -(A + B)
1090 if (Value *LHSV = dyn_castNegVal(LHS)) {
1091 if (!isa<Constant>(RHS))
1092 if (Value *RHSV = dyn_castNegVal(RHS)) {
1093 Value *NewAdd = Builder->CreateAdd(LHSV, RHSV, "sum");
1094 return BinaryOperator::CreateNeg(NewAdd);
1097 return BinaryOperator::CreateSub(RHS, LHSV);
1101 if (!isa<Constant>(RHS))
1102 if (Value *V = dyn_castNegVal(RHS))
1103 return BinaryOperator::CreateSub(LHS, V);
1105 if (Value *V = checkForNegativeOperand(I, Builder))
1106 return replaceInstUsesWith(I, V);
1108 // A+B --> A|B iff A and B have no bits set in common.
1109 if (haveNoCommonBitsSet(LHS, RHS, DL, &AC, &I, &DT))
1110 return BinaryOperator::CreateOr(LHS, RHS);
1112 if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
1114 if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X
1115 return BinaryOperator::CreateSub(SubOne(CRHS), X);
1118 // FIXME: We already did a check for ConstantInt RHS above this.
1119 // FIXME: Is this pattern covered by another fold? No regression tests fail on
1121 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
1122 // (X & FF00) + xx00 -> (X+xx00) & FF00
1125 if (LHS->hasOneUse() &&
1126 match(LHS, m_And(m_Value(X), m_ConstantInt(C2))) &&
1127 CRHS->getValue() == (CRHS->getValue() & C2->getValue())) {
1128 // See if all bits from the first bit set in the Add RHS up are included
1129 // in the mask. First, get the rightmost bit.
1130 const APInt &AddRHSV = CRHS->getValue();
1132 // Form a mask of all bits from the lowest bit added through the top.
1133 APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1));
1135 // See if the and mask includes all of these bits.
1136 APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue());
1138 if (AddRHSHighBits == AddRHSHighBitsAnd) {
1139 // Okay, the xform is safe. Insert the new add pronto.
1140 Value *NewAdd = Builder->CreateAdd(X, CRHS, LHS->getName());
1141 return BinaryOperator::CreateAnd(NewAdd, C2);
1146 // add (select X 0 (sub n A)) A --> select X A n
1148 SelectInst *SI = dyn_cast<SelectInst>(LHS);
1151 SI = dyn_cast<SelectInst>(RHS);
1154 if (SI && SI->hasOneUse()) {
1155 Value *TV = SI->getTrueValue();
1156 Value *FV = SI->getFalseValue();
1159 // Can we fold the add into the argument of the select?
1160 // We check both true and false select arguments for a matching subtract.
1161 if (match(FV, m_Zero()) && match(TV, m_Sub(m_Value(N), m_Specific(A))))
1162 // Fold the add into the true select value.
1163 return SelectInst::Create(SI->getCondition(), N, A);
1165 if (match(TV, m_Zero()) && match(FV, m_Sub(m_Value(N), m_Specific(A))))
1166 // Fold the add into the false select value.
1167 return SelectInst::Create(SI->getCondition(), A, N);
1171 // Check for (add (sext x), y), see if we can merge this into an
1172 // integer add followed by a sext.
1173 if (SExtInst *LHSConv = dyn_cast<SExtInst>(LHS)) {
1174 // (add (sext x), cst) --> (sext (add x, cst'))
1175 if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
1176 if (LHSConv->hasOneUse()) {
1178 ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType());
1179 if (ConstantExpr::getSExt(CI, I.getType()) == RHSC &&
1180 willNotOverflowSignedAdd(LHSConv->getOperand(0), CI, I)) {
1181 // Insert the new, smaller add.
1183 Builder->CreateNSWAdd(LHSConv->getOperand(0), CI, "addconv");
1184 return new SExtInst(NewAdd, I.getType());
1189 // (add (sext x), (sext y)) --> (sext (add int x, y))
1190 if (SExtInst *RHSConv = dyn_cast<SExtInst>(RHS)) {
1191 // Only do this if x/y have the same type, if at least one of them has a
1192 // single use (so we don't increase the number of sexts), and if the
1193 // integer add will not overflow.
1194 if (LHSConv->getOperand(0)->getType() ==
1195 RHSConv->getOperand(0)->getType() &&
1196 (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
1197 willNotOverflowSignedAdd(LHSConv->getOperand(0),
1198 RHSConv->getOperand(0), I)) {
1199 // Insert the new integer add.
1200 Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
1201 RHSConv->getOperand(0), "addconv");
1202 return new SExtInst(NewAdd, I.getType());
1207 // Check for (add (zext x), y), see if we can merge this into an
1208 // integer add followed by a zext.
1209 if (auto *LHSConv = dyn_cast<ZExtInst>(LHS)) {
1210 // (add (zext x), cst) --> (zext (add x, cst'))
1211 if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
1212 if (LHSConv->hasOneUse()) {
1214 ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType());
1215 if (ConstantExpr::getZExt(CI, I.getType()) == RHSC &&
1216 willNotOverflowUnsignedAdd(LHSConv->getOperand(0), CI, I)) {
1217 // Insert the new, smaller add.
1219 Builder->CreateNUWAdd(LHSConv->getOperand(0), CI, "addconv");
1220 return new ZExtInst(NewAdd, I.getType());
1225 // (add (zext x), (zext y)) --> (zext (add int x, y))
1226 if (auto *RHSConv = dyn_cast<ZExtInst>(RHS)) {
1227 // Only do this if x/y have the same type, if at least one of them has a
1228 // single use (so we don't increase the number of zexts), and if the
1229 // integer add will not overflow.
1230 if (LHSConv->getOperand(0)->getType() ==
1231 RHSConv->getOperand(0)->getType() &&
1232 (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
1233 willNotOverflowUnsignedAdd(LHSConv->getOperand(0),
1234 RHSConv->getOperand(0), I)) {
1235 // Insert the new integer add.
1236 Value *NewAdd = Builder->CreateNUWAdd(
1237 LHSConv->getOperand(0), RHSConv->getOperand(0), "addconv");
1238 return new ZExtInst(NewAdd, I.getType());
1243 // (add (xor A, B) (and A, B)) --> (or A, B)
1245 Value *A = nullptr, *B = nullptr;
1246 if (match(RHS, m_Xor(m_Value(A), m_Value(B))) &&
1247 match(LHS, m_c_And(m_Specific(A), m_Specific(B))))
1248 return BinaryOperator::CreateOr(A, B);
1250 if (match(LHS, m_Xor(m_Value(A), m_Value(B))) &&
1251 match(RHS, m_c_And(m_Specific(A), m_Specific(B))))
1252 return BinaryOperator::CreateOr(A, B);
1255 // (add (or A, B) (and A, B)) --> (add A, B)
1257 Value *A = nullptr, *B = nullptr;
1258 if (match(RHS, m_Or(m_Value(A), m_Value(B))) &&
1259 match(LHS, m_c_And(m_Specific(A), m_Specific(B)))) {
1260 auto *New = BinaryOperator::CreateAdd(A, B);
1261 New->setHasNoSignedWrap(I.hasNoSignedWrap());
1262 New->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
1266 if (match(LHS, m_Or(m_Value(A), m_Value(B))) &&
1267 match(RHS, m_c_And(m_Specific(A), m_Specific(B)))) {
1268 auto *New = BinaryOperator::CreateAdd(A, B);
1269 New->setHasNoSignedWrap(I.hasNoSignedWrap());
1270 New->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
1275 // TODO(jingyue): Consider willNotOverflowSignedAdd and
1276 // willNotOverflowUnsignedAdd to reduce the number of invocations of
1277 // computeKnownBits.
1278 if (!I.hasNoSignedWrap() && willNotOverflowSignedAdd(LHS, RHS, I)) {
1280 I.setHasNoSignedWrap(true);
1282 if (!I.hasNoUnsignedWrap() && willNotOverflowUnsignedAdd(LHS, RHS, I)) {
1284 I.setHasNoUnsignedWrap(true);
1287 return Changed ? &I : nullptr;
1290 Instruction *InstCombiner::visitFAdd(BinaryOperator &I) {
1291 bool Changed = SimplifyAssociativeOrCommutative(I);
1292 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
1294 if (Value *V = SimplifyVectorOp(I))
1295 return replaceInstUsesWith(I, V);
1297 if (Value *V = SimplifyFAddInst(LHS, RHS, I.getFastMathFlags(), SQ))
1298 return replaceInstUsesWith(I, V);
1300 if (isa<Constant>(RHS))
1301 if (Instruction *FoldedFAdd = foldOpWithConstantIntoOperand(I))
1305 // -A + -B --> -(A + B)
1306 if (Value *LHSV = dyn_castFNegVal(LHS)) {
1307 Instruction *RI = BinaryOperator::CreateFSub(RHS, LHSV);
1308 RI->copyFastMathFlags(&I);
1313 if (!isa<Constant>(RHS))
1314 if (Value *V = dyn_castFNegVal(RHS)) {
1315 Instruction *RI = BinaryOperator::CreateFSub(LHS, V);
1316 RI->copyFastMathFlags(&I);
1320 // Check for (fadd double (sitofp x), y), see if we can merge this into an
1321 // integer add followed by a promotion.
1322 if (SIToFPInst *LHSConv = dyn_cast<SIToFPInst>(LHS)) {
1323 Value *LHSIntVal = LHSConv->getOperand(0);
1324 Type *FPType = LHSConv->getType();
1326 // TODO: This check is overly conservative. In many cases known bits
1327 // analysis can tell us that the result of the addition has less significant
1328 // bits than the integer type can hold.
1329 auto IsValidPromotion = [](Type *FTy, Type *ITy) {
1330 Type *FScalarTy = FTy->getScalarType();
1331 Type *IScalarTy = ITy->getScalarType();
1333 // Do we have enough bits in the significand to represent the result of
1334 // the integer addition?
1335 unsigned MaxRepresentableBits =
1336 APFloat::semanticsPrecision(FScalarTy->getFltSemantics());
1337 return IScalarTy->getIntegerBitWidth() <= MaxRepresentableBits;
1340 // (fadd double (sitofp x), fpcst) --> (sitofp (add int x, intcst))
1341 // ... if the constant fits in the integer value. This is useful for things
1342 // like (double)(x & 1234) + 4.0 -> (double)((X & 1234)+4) which no longer
1343 // requires a constant pool load, and generally allows the add to be better
1345 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS))
1346 if (IsValidPromotion(FPType, LHSIntVal->getType())) {
1348 ConstantExpr::getFPToSI(CFP, LHSIntVal->getType());
1349 if (LHSConv->hasOneUse() &&
1350 ConstantExpr::getSIToFP(CI, I.getType()) == CFP &&
1351 willNotOverflowSignedAdd(LHSIntVal, CI, I)) {
1352 // Insert the new integer add.
1353 Value *NewAdd = Builder->CreateNSWAdd(LHSIntVal,
1355 return new SIToFPInst(NewAdd, I.getType());
1359 // (fadd double (sitofp x), (sitofp y)) --> (sitofp (add int x, y))
1360 if (SIToFPInst *RHSConv = dyn_cast<SIToFPInst>(RHS)) {
1361 Value *RHSIntVal = RHSConv->getOperand(0);
1362 // It's enough to check LHS types only because we require int types to
1363 // be the same for this transform.
1364 if (IsValidPromotion(FPType, LHSIntVal->getType())) {
1365 // Only do this if x/y have the same type, if at least one of them has a
1366 // single use (so we don't increase the number of int->fp conversions),
1367 // and if the integer add will not overflow.
1368 if (LHSIntVal->getType() == RHSIntVal->getType() &&
1369 (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
1370 willNotOverflowSignedAdd(LHSIntVal, RHSIntVal, I)) {
1371 // Insert the new integer add.
1372 Value *NewAdd = Builder->CreateNSWAdd(LHSIntVal,
1373 RHSIntVal, "addconv");
1374 return new SIToFPInst(NewAdd, I.getType());
1380 // select C, 0, B + select C, A, 0 -> select C, A, B
1382 Value *A1, *B1, *C1, *A2, *B2, *C2;
1383 if (match(LHS, m_Select(m_Value(C1), m_Value(A1), m_Value(B1))) &&
1384 match(RHS, m_Select(m_Value(C2), m_Value(A2), m_Value(B2)))) {
1386 Constant *Z1=nullptr, *Z2=nullptr;
1387 Value *A, *B, *C=C1;
1388 if (match(A1, m_AnyZero()) && match(B2, m_AnyZero())) {
1389 Z1 = dyn_cast<Constant>(A1); A = A2;
1390 Z2 = dyn_cast<Constant>(B2); B = B1;
1391 } else if (match(B1, m_AnyZero()) && match(A2, m_AnyZero())) {
1392 Z1 = dyn_cast<Constant>(B1); B = B2;
1393 Z2 = dyn_cast<Constant>(A2); A = A1;
1397 (I.hasNoSignedZeros() ||
1398 (Z1->isNegativeZeroValue() && Z2->isNegativeZeroValue()))) {
1399 return SelectInst::Create(C, A, B);
1405 if (I.hasUnsafeAlgebra()) {
1406 if (Value *V = FAddCombine(Builder).simplify(&I))
1407 return replaceInstUsesWith(I, V);
1410 return Changed ? &I : nullptr;
1413 /// Optimize pointer differences into the same array into a size. Consider:
1414 /// &A[10] - &A[0]: we should compile this to "10". LHS/RHS are the pointer
1415 /// operands to the ptrtoint instructions for the LHS/RHS of the subtract.
1417 Value *InstCombiner::OptimizePointerDifference(Value *LHS, Value *RHS,
1419 // If LHS is a gep based on RHS or RHS is a gep based on LHS, we can optimize
1421 bool Swapped = false;
1422 GEPOperator *GEP1 = nullptr, *GEP2 = nullptr;
1424 // For now we require one side to be the base pointer "A" or a constant
1425 // GEP derived from it.
1426 if (GEPOperator *LHSGEP = dyn_cast<GEPOperator>(LHS)) {
1428 if (LHSGEP->getOperand(0) == RHS) {
1431 } else if (GEPOperator *RHSGEP = dyn_cast<GEPOperator>(RHS)) {
1432 // (gep X, ...) - (gep X, ...)
1433 if (LHSGEP->getOperand(0)->stripPointerCasts() ==
1434 RHSGEP->getOperand(0)->stripPointerCasts()) {
1442 if (GEPOperator *RHSGEP = dyn_cast<GEPOperator>(RHS)) {
1444 if (RHSGEP->getOperand(0) == LHS) {
1447 } else if (GEPOperator *LHSGEP = dyn_cast<GEPOperator>(LHS)) {
1448 // (gep X, ...) - (gep X, ...)
1449 if (RHSGEP->getOperand(0)->stripPointerCasts() ==
1450 LHSGEP->getOperand(0)->stripPointerCasts()) {
1458 // Avoid duplicating the arithmetic if GEP2 has non-constant indices and
1461 (GEP2 && !GEP2->hasAllConstantIndices() && !GEP2->hasOneUse()))
1464 // Emit the offset of the GEP and an intptr_t.
1465 Value *Result = EmitGEPOffset(GEP1);
1467 // If we had a constant expression GEP on the other side offsetting the
1468 // pointer, subtract it from the offset we have.
1470 Value *Offset = EmitGEPOffset(GEP2);
1471 Result = Builder->CreateSub(Result, Offset);
1474 // If we have p - gep(p, ...) then we have to negate the result.
1476 Result = Builder->CreateNeg(Result, "diff.neg");
1478 return Builder->CreateIntCast(Result, Ty, true);
1481 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
1482 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1484 if (Value *V = SimplifyVectorOp(I))
1485 return replaceInstUsesWith(I, V);
1487 if (Value *V = SimplifySubInst(Op0, Op1, I.hasNoSignedWrap(),
1488 I.hasNoUnsignedWrap(), SQ))
1489 return replaceInstUsesWith(I, V);
1491 // (A*B)-(A*C) -> A*(B-C) etc
1492 if (Value *V = SimplifyUsingDistributiveLaws(I))
1493 return replaceInstUsesWith(I, V);
1495 // If this is a 'B = x-(-A)', change to B = x+A.
1496 if (Value *V = dyn_castNegVal(Op1)) {
1497 BinaryOperator *Res = BinaryOperator::CreateAdd(Op0, V);
1499 if (const auto *BO = dyn_cast<BinaryOperator>(Op1)) {
1500 assert(BO->getOpcode() == Instruction::Sub &&
1501 "Expected a subtraction operator!");
1502 if (BO->hasNoSignedWrap() && I.hasNoSignedWrap())
1503 Res->setHasNoSignedWrap(true);
1505 if (cast<Constant>(Op1)->isNotMinSignedValue() && I.hasNoSignedWrap())
1506 Res->setHasNoSignedWrap(true);
1512 if (I.getType()->getScalarType()->isIntegerTy(1))
1513 return BinaryOperator::CreateXor(Op0, Op1);
1515 // Replace (-1 - A) with (~A).
1516 if (match(Op0, m_AllOnes()))
1517 return BinaryOperator::CreateNot(Op1);
1519 if (Constant *C = dyn_cast<Constant>(Op0)) {
1520 // C - ~X == X + (1+C)
1522 if (match(Op1, m_Not(m_Value(X))))
1523 return BinaryOperator::CreateAdd(X, AddOne(C));
1525 // Try to fold constant sub into select arguments.
1526 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1527 if (Instruction *R = FoldOpIntoSelect(I, SI))
1530 // Try to fold constant sub into PHI values.
1531 if (PHINode *PN = dyn_cast<PHINode>(Op1))
1532 if (Instruction *R = foldOpIntoPhi(I, PN))
1535 // C-(X+C2) --> (C-C2)-X
1537 if (match(Op1, m_Add(m_Value(X), m_Constant(C2))))
1538 return BinaryOperator::CreateSub(ConstantExpr::getSub(C, C2), X);
1540 // Fold (sub 0, (zext bool to B)) --> (sext bool to B)
1541 if (C->isNullValue() && match(Op1, m_ZExt(m_Value(X))))
1542 if (X->getType()->getScalarType()->isIntegerTy(1))
1543 return CastInst::CreateSExtOrBitCast(X, Op1->getType());
1545 // Fold (sub 0, (sext bool to B)) --> (zext bool to B)
1546 if (C->isNullValue() && match(Op1, m_SExt(m_Value(X))))
1547 if (X->getType()->getScalarType()->isIntegerTy(1))
1548 return CastInst::CreateZExtOrBitCast(X, Op1->getType());
1552 if (match(Op0, m_APInt(Op0C))) {
1553 unsigned BitWidth = I.getType()->getScalarSizeInBits();
1555 // -(X >>u 31) -> (X >>s 31)
1556 // -(X >>s 31) -> (X >>u 31)
1560 if (match(Op1, m_LShr(m_Value(X), m_APInt(ShAmt))) &&
1561 *ShAmt == BitWidth - 1) {
1562 Value *ShAmtOp = cast<Instruction>(Op1)->getOperand(1);
1563 return BinaryOperator::CreateAShr(X, ShAmtOp);
1565 if (match(Op1, m_AShr(m_Value(X), m_APInt(ShAmt))) &&
1566 *ShAmt == BitWidth - 1) {
1567 Value *ShAmtOp = cast<Instruction>(Op1)->getOperand(1);
1568 return BinaryOperator::CreateLShr(X, ShAmtOp);
1572 // Turn this into a xor if LHS is 2^n-1 and the remaining bits are known
1574 if (Op0C->isMask()) {
1575 KnownBits RHSKnown = computeKnownBits(Op1, 0, &I);
1576 if ((*Op0C | RHSKnown.Zero).isAllOnesValue())
1577 return BinaryOperator::CreateXor(Op1, Op0);
1583 // X-(X+Y) == -Y X-(Y+X) == -Y
1584 if (match(Op1, m_c_Add(m_Specific(Op0), m_Value(Y))))
1585 return BinaryOperator::CreateNeg(Y);
1588 if (match(Op0, m_Sub(m_Specific(Op1), m_Value(Y))))
1589 return BinaryOperator::CreateNeg(Y);
1592 // (sub (or A, B) (xor A, B)) --> (and A, B)
1595 if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
1596 match(Op0, m_c_Or(m_Specific(A), m_Specific(B))))
1597 return BinaryOperator::CreateAnd(A, B);
1602 // ((X | Y) - X) --> (~X & Y)
1603 if (match(Op0, m_OneUse(m_c_Or(m_Value(Y), m_Specific(Op1)))))
1604 return BinaryOperator::CreateAnd(
1605 Y, Builder->CreateNot(Op1, Op1->getName() + ".not"));
1608 if (Op1->hasOneUse()) {
1609 Value *X = nullptr, *Y = nullptr, *Z = nullptr;
1610 Constant *C = nullptr;
1612 // (X - (Y - Z)) --> (X + (Z - Y)).
1613 if (match(Op1, m_Sub(m_Value(Y), m_Value(Z))))
1614 return BinaryOperator::CreateAdd(Op0,
1615 Builder->CreateSub(Z, Y, Op1->getName()));
1617 // (X - (X & Y)) --> (X & ~Y)
1619 if (match(Op1, m_c_And(m_Value(Y), m_Specific(Op0))))
1620 return BinaryOperator::CreateAnd(Op0,
1621 Builder->CreateNot(Y, Y->getName() + ".not"));
1623 // 0 - (X sdiv C) -> (X sdiv -C) provided the negation doesn't overflow.
1624 if (match(Op1, m_SDiv(m_Value(X), m_Constant(C))) && match(Op0, m_Zero()) &&
1625 C->isNotMinSignedValue() && !C->isOneValue())
1626 return BinaryOperator::CreateSDiv(X, ConstantExpr::getNeg(C));
1628 // 0 - (X << Y) -> (-X << Y) when X is freely negatable.
1629 if (match(Op1, m_Shl(m_Value(X), m_Value(Y))) && match(Op0, m_Zero()))
1630 if (Value *XNeg = dyn_castNegVal(X))
1631 return BinaryOperator::CreateShl(XNeg, Y);
1633 // Subtracting -1/0 is the same as adding 1/0:
1634 // sub [nsw] Op0, sext(bool Y) -> add [nsw] Op0, zext(bool Y)
1635 // 'nuw' is dropped in favor of the canonical form.
1636 if (match(Op1, m_SExt(m_Value(Y))) &&
1637 Y->getType()->getScalarSizeInBits() == 1) {
1638 Value *Zext = Builder->CreateZExt(Y, I.getType());
1639 BinaryOperator *Add = BinaryOperator::CreateAdd(Op0, Zext);
1640 Add->setHasNoSignedWrap(I.hasNoSignedWrap());
1644 // X - A*-B -> X + A*B
1645 // X - -A*B -> X + A*B
1648 if (match(Op1, m_c_Mul(m_Value(A), m_Neg(m_Value(B)))))
1649 return BinaryOperator::CreateAdd(Op0, Builder->CreateMul(A, B));
1651 // X - A*CI -> X + A*-CI
1652 // No need to handle commuted multiply because multiply handling will
1653 // ensure constant will be move to the right hand side.
1654 if (match(Op1, m_Mul(m_Value(A), m_Constant(CI)))) {
1655 Value *NewMul = Builder->CreateMul(A, ConstantExpr::getNeg(CI));
1656 return BinaryOperator::CreateAdd(Op0, NewMul);
1660 // Optimize pointer differences into the same array into a size. Consider:
1661 // &A[10] - &A[0]: we should compile this to "10".
1662 Value *LHSOp, *RHSOp;
1663 if (match(Op0, m_PtrToInt(m_Value(LHSOp))) &&
1664 match(Op1, m_PtrToInt(m_Value(RHSOp))))
1665 if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
1666 return replaceInstUsesWith(I, Res);
1668 // trunc(p)-trunc(q) -> trunc(p-q)
1669 if (match(Op0, m_Trunc(m_PtrToInt(m_Value(LHSOp)))) &&
1670 match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp)))))
1671 if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
1672 return replaceInstUsesWith(I, Res);
1674 bool Changed = false;
1675 if (!I.hasNoSignedWrap() && willNotOverflowSignedSub(Op0, Op1, I)) {
1677 I.setHasNoSignedWrap(true);
1679 if (!I.hasNoUnsignedWrap() && willNotOverflowUnsignedSub(Op0, Op1, I)) {
1681 I.setHasNoUnsignedWrap(true);
1684 return Changed ? &I : nullptr;
1687 Instruction *InstCombiner::visitFSub(BinaryOperator &I) {
1688 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1690 if (Value *V = SimplifyVectorOp(I))
1691 return replaceInstUsesWith(I, V);
1693 if (Value *V = SimplifyFSubInst(Op0, Op1, I.getFastMathFlags(), SQ))
1694 return replaceInstUsesWith(I, V);
1696 // fsub nsz 0, X ==> fsub nsz -0.0, X
1697 if (I.getFastMathFlags().noSignedZeros() && match(Op0, m_Zero())) {
1698 // Subtraction from -0.0 is the canonical form of fneg.
1699 Instruction *NewI = BinaryOperator::CreateFNeg(Op1);
1700 NewI->copyFastMathFlags(&I);
1704 if (isa<Constant>(Op0))
1705 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1706 if (Instruction *NV = FoldOpIntoSelect(I, SI))
1709 // If this is a 'B = x-(-A)', change to B = x+A, potentially looking
1710 // through FP extensions/truncations along the way.
1711 if (Value *V = dyn_castFNegVal(Op1)) {
1712 Instruction *NewI = BinaryOperator::CreateFAdd(Op0, V);
1713 NewI->copyFastMathFlags(&I);
1716 if (FPTruncInst *FPTI = dyn_cast<FPTruncInst>(Op1)) {
1717 if (Value *V = dyn_castFNegVal(FPTI->getOperand(0))) {
1718 Value *NewTrunc = Builder->CreateFPTrunc(V, I.getType());
1719 Instruction *NewI = BinaryOperator::CreateFAdd(Op0, NewTrunc);
1720 NewI->copyFastMathFlags(&I);
1723 } else if (FPExtInst *FPEI = dyn_cast<FPExtInst>(Op1)) {
1724 if (Value *V = dyn_castFNegVal(FPEI->getOperand(0))) {
1725 Value *NewExt = Builder->CreateFPExt(V, I.getType());
1726 Instruction *NewI = BinaryOperator::CreateFAdd(Op0, NewExt);
1727 NewI->copyFastMathFlags(&I);
1732 if (I.hasUnsafeAlgebra()) {
1733 if (Value *V = FAddCombine(Builder).simplify(&I))
1734 return replaceInstUsesWith(I, V);