1 //===- InstCombineAddSub.cpp ----------------------------------------------===//
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 "InstCombine.h"
15 #include "llvm/Analysis/InstructionSimplify.h"
16 #include "llvm/IR/DataLayout.h"
17 #include "llvm/Support/GetElementPtrTypeIterator.h"
18 #include "llvm/Support/PatternMatch.h"
20 using namespace PatternMatch;
24 /// Class representing coefficient of floating-point addend.
25 /// This class needs to be highly efficient, which is especially true for
26 /// the constructor. As of I write this comment, the cost of the default
27 /// constructor is merely 4-byte-store-zero (Assuming compiler is able to
28 /// perform write-merging).
32 // The constructor has to initialize a APFloat, which is uncessary for
33 // most addends which have coefficient either 1 or -1. So, the constructor
34 // is expensive. In order to avoid the cost of the constructor, we should
35 // reuse some instances whenever possible. The pre-created instances
36 // FAddCombine::Add[0-5] embodies this idea.
38 FAddendCoef() : IsFp(false), BufHasFpVal(false), IntVal(0) {}
42 assert(!insaneIntVal(C) && "Insane coefficient");
43 IsFp = false; IntVal = C;
46 void set(const APFloat& C);
50 bool isZero() const { return isInt() ? !IntVal : getFpVal().isZero(); }
51 Value *getValue(Type *) const;
53 // If possible, don't define operator+/operator- etc because these
54 // operators inevitably call FAddendCoef's constructor which is not cheap.
55 void operator=(const FAddendCoef &A);
56 void operator+=(const FAddendCoef &A);
57 void operator-=(const FAddendCoef &A);
58 void operator*=(const FAddendCoef &S);
60 bool isOne() const { return isInt() && IntVal == 1; }
61 bool isTwo() const { return isInt() && IntVal == 2; }
62 bool isMinusOne() const { return isInt() && IntVal == -1; }
63 bool isMinusTwo() const { return isInt() && IntVal == -2; }
66 bool insaneIntVal(int V) { return V > 4 || V < -4; }
67 APFloat *getFpValPtr(void)
68 { return reinterpret_cast<APFloat*>(&FpValBuf.buffer[0]); }
69 const APFloat *getFpValPtr(void) const
70 { return reinterpret_cast<const APFloat*>(&FpValBuf.buffer[0]); }
72 const APFloat &getFpVal(void) const {
73 assert(IsFp && BufHasFpVal && "Incorret state");
74 return *getFpValPtr();
77 APFloat &getFpVal(void)
78 { assert(IsFp && BufHasFpVal && "Incorret state"); return *getFpValPtr(); }
80 bool isInt() const { return !IsFp; }
86 // True iff FpValBuf contains an instance of APFloat.
89 // The integer coefficient of an individual addend is either 1 or -1,
90 // and we try to simplify at most 4 addends from neighboring at most
91 // two instructions. So the range of <IntVal> falls in [-4, 4]. APInt
92 // is overkill of this end.
95 AlignedCharArrayUnion<APFloat> FpValBuf;
98 /// FAddend is used to represent floating-point addend. An addend is
99 /// represented as <C, V>, where the V is a symbolic value, and C is a
100 /// constant coefficient. A constant addend is represented as <C, 0>.
104 FAddend() { Val = 0; }
106 Value *getSymVal (void) const { return Val; }
107 const FAddendCoef &getCoef(void) const { return Coeff; }
109 bool isConstant() const { return Val == 0; }
110 bool isZero() const { return Coeff.isZero(); }
112 void set(short Coefficient, Value *V) { Coeff.set(Coefficient), Val = V; }
113 void set(const APFloat& Coefficient, Value *V)
114 { Coeff.set(Coefficient); Val = V; }
115 void set(const ConstantFP* Coefficient, Value *V)
116 { Coeff.set(Coefficient->getValueAPF()); Val = V; }
118 void negate() { Coeff.negate(); }
120 /// Drill down the U-D chain one step to find the definition of V, and
121 /// try to break the definition into one or two addends.
122 static unsigned drillValueDownOneStep(Value* V, FAddend &A0, FAddend &A1);
124 /// Similar to FAddend::drillDownOneStep() except that the value being
125 /// splitted is the addend itself.
126 unsigned drillAddendDownOneStep(FAddend &Addend0, FAddend &Addend1) const;
128 void operator+=(const FAddend &T) {
129 assert((Val == T.Val) && "Symbolic-values disagree");
134 void Scale(const FAddendCoef& ScaleAmt) { Coeff *= ScaleAmt; }
136 // This addend has the value of "Coeff * Val".
141 /// FAddCombine is the class for optimizing an unsafe fadd/fsub along
142 /// with its neighboring at most two instructions.
146 FAddCombine(InstCombiner::BuilderTy *B) : Builder(B), Instr(0) {}
147 Value *simplify(Instruction *FAdd);
150 typedef SmallVector<const FAddend*, 4> AddendVect;
152 Value *simplifyFAdd(AddendVect& V, unsigned InstrQuota);
154 Value *performFactorization(Instruction *I);
156 /// Convert given addend to a Value
157 Value *createAddendVal(const FAddend &A, bool& NeedNeg);
159 /// Return the number of instructions needed to emit the N-ary addition.
160 unsigned calcInstrNumber(const AddendVect& Vect);
161 Value *createFSub(Value *Opnd0, Value *Opnd1);
162 Value *createFAdd(Value *Opnd0, Value *Opnd1);
163 Value *createFMul(Value *Opnd0, Value *Opnd1);
164 Value *createFDiv(Value *Opnd0, Value *Opnd1);
165 Value *createFNeg(Value *V);
166 Value *createNaryFAdd(const AddendVect& Opnds, unsigned InstrQuota);
167 void createInstPostProc(Instruction *NewInst);
169 InstCombiner::BuilderTy *Builder;
173 // Debugging stuff are clustered here.
175 unsigned CreateInstrNum;
176 void initCreateInstNum() { CreateInstrNum = 0; }
177 void incCreateInstNum() { CreateInstrNum++; }
179 void initCreateInstNum() {}
180 void incCreateInstNum() {}
185 //===----------------------------------------------------------------------===//
188 // {FAddendCoef, FAddend, FAddition, FAddCombine}.
190 //===----------------------------------------------------------------------===//
191 FAddendCoef::~FAddendCoef() {
193 getFpValPtr()->~APFloat();
196 void FAddendCoef::set(const APFloat& C) {
197 APFloat *P = getFpValPtr();
200 // As the buffer is meanless byte stream, we cannot call
201 // APFloat::operator=().
206 IsFp = BufHasFpVal = true;
209 void FAddendCoef::operator=(const FAddendCoef& That) {
213 set(That.getFpVal());
216 void FAddendCoef::operator+=(const FAddendCoef &That) {
217 enum APFloat::roundingMode RndMode = APFloat::rmNearestTiesToEven;
218 if (isInt() == That.isInt()) {
220 IntVal += That.IntVal;
222 getFpVal().add(That.getFpVal(), RndMode);
227 const APFloat &T = That.getFpVal();
229 getFpVal().add(APFloat(T.getSemantics(), IntVal), RndMode);
233 APFloat &T = getFpVal();
234 T.add(APFloat(T.getSemantics(), That.IntVal), RndMode);
237 void FAddendCoef::operator-=(const FAddendCoef &That) {
238 enum APFloat::roundingMode RndMode = APFloat::rmNearestTiesToEven;
239 if (isInt() == That.isInt()) {
241 IntVal -= That.IntVal;
243 getFpVal().subtract(That.getFpVal(), RndMode);
248 const APFloat &T = That.getFpVal();
250 getFpVal().subtract(APFloat(T.getSemantics(), IntVal), RndMode);
254 APFloat &T = getFpVal();
255 T.subtract(APFloat(T.getSemantics(), IntVal), RndMode);
258 void FAddendCoef::operator*=(const FAddendCoef &That) {
262 if (That.isMinusOne()) {
267 if (isInt() && That.isInt()) {
268 int Res = IntVal * (int)That.IntVal;
269 assert(!insaneIntVal(Res) && "Insane int value");
274 const fltSemantics &Semantic =
275 isInt() ? That.getFpVal().getSemantics() : getFpVal().getSemantics();
278 set(APFloat(Semantic, IntVal));
279 APFloat &F0 = getFpVal();
282 F0.multiply(APFloat(Semantic, That.IntVal), APFloat::rmNearestTiesToEven);
284 F0.multiply(That.getFpVal(), APFloat::rmNearestTiesToEven);
289 void FAddendCoef::negate() {
293 getFpVal().changeSign();
296 Value *FAddendCoef::getValue(Type *Ty) const {
298 ConstantFP::get(Ty, float(IntVal)) :
299 ConstantFP::get(Ty->getContext(), getFpVal());
302 // The definition of <Val> Addends
303 // =========================================
304 // A + B <1, A>, <1,B>
305 // A - B <1, A>, <1,B>
308 // A + C <1, A> <C, NULL>
309 // 0 +/- 0 <0, NULL> (corner case)
311 // Legend: A and B are not constant, C is constant
313 unsigned FAddend::drillValueDownOneStep
314 (Value *Val, FAddend &Addend0, FAddend &Addend1) {
316 if (Val == 0 || !(I = dyn_cast<Instruction>(Val)))
319 unsigned Opcode = I->getOpcode();
321 if (Opcode == Instruction::FAdd || Opcode == Instruction::FSub) {
323 Value *Opnd0 = I->getOperand(0);
324 Value *Opnd1 = I->getOperand(1);
325 if ((C0 = dyn_cast<ConstantFP>(Opnd0)) && C0->isZero())
328 if ((C1 = dyn_cast<ConstantFP>(Opnd1)) && C1->isZero())
333 Addend0.set(1, Opnd0);
339 FAddend &Addend = Opnd0 ? Addend1 : Addend0;
341 Addend.set(1, Opnd1);
344 if (Opcode == Instruction::FSub)
349 return Opnd0 && Opnd1 ? 2 : 1;
351 // Both operands are zero. Weird!
352 Addend0.set(APFloat(C0->getValueAPF().getSemantics()), 0);
356 if (I->getOpcode() == Instruction::FMul) {
357 Value *V0 = I->getOperand(0);
358 Value *V1 = I->getOperand(1);
359 if (ConstantFP *C = dyn_cast<ConstantFP>(V0)) {
364 if (ConstantFP *C = dyn_cast<ConstantFP>(V1)) {
373 // Try to break *this* addend into two addends. e.g. Suppose this addend is
374 // <2.3, V>, and V = X + Y, by calling this function, we obtain two addends,
375 // i.e. <2.3, X> and <2.3, Y>.
377 unsigned FAddend::drillAddendDownOneStep
378 (FAddend &Addend0, FAddend &Addend1) const {
382 unsigned BreakNum = FAddend::drillValueDownOneStep(Val, Addend0, Addend1);
383 if (!BreakNum || Coeff.isOne())
386 Addend0.Scale(Coeff);
389 Addend1.Scale(Coeff);
394 // Try to perform following optimization on the input instruction I. Return the
395 // simplified expression if was successful; otherwise, return 0.
397 // Instruction "I" is Simplified into
398 // -------------------------------------------------------
399 // (x * y) +/- (x * z) x * (y +/- z)
400 // (y / x) +/- (z / x) (y +/- z) / x
402 Value *FAddCombine::performFactorization(Instruction *I) {
403 assert((I->getOpcode() == Instruction::FAdd ||
404 I->getOpcode() == Instruction::FSub) && "Expect add/sub");
406 Instruction *I0 = dyn_cast<Instruction>(I->getOperand(0));
407 Instruction *I1 = dyn_cast<Instruction>(I->getOperand(1));
409 if (!I0 || !I1 || I0->getOpcode() != I1->getOpcode())
413 if (I0->getOpcode() == Instruction::FMul)
415 else if (I0->getOpcode() != Instruction::FDiv)
418 Value *Opnd0_0 = I0->getOperand(0);
419 Value *Opnd0_1 = I0->getOperand(1);
420 Value *Opnd1_0 = I1->getOperand(0);
421 Value *Opnd1_1 = I1->getOperand(1);
423 // Input Instr I Factor AddSub0 AddSub1
424 // ----------------------------------------------
425 // (x*y) +/- (x*z) x y z
426 // (y/x) +/- (z/x) x y z
429 Value *AddSub0 = 0, *AddSub1 = 0;
432 if (Opnd0_0 == Opnd1_0 || Opnd0_0 == Opnd1_1)
434 else if (Opnd0_1 == Opnd1_0 || Opnd0_1 == Opnd1_1)
438 AddSub0 = (Factor == Opnd0_0) ? Opnd0_1 : Opnd0_0;
439 AddSub1 = (Factor == Opnd1_0) ? Opnd1_1 : Opnd1_0;
441 } else if (Opnd0_1 == Opnd1_1) {
450 // Create expression "NewAddSub = AddSub0 +/- AddsSub1"
451 Value *NewAddSub = (I->getOpcode() == Instruction::FAdd) ?
452 createFAdd(AddSub0, AddSub1) :
453 createFSub(AddSub0, AddSub1);
454 if (ConstantFP *CFP = dyn_cast<ConstantFP>(NewAddSub)) {
455 const APFloat &F = CFP->getValueAPF();
456 if (!F.isNormal() || F.isDenormal())
461 return createFMul(Factor, NewAddSub);
463 return createFDiv(NewAddSub, Factor);
466 Value *FAddCombine::simplify(Instruction *I) {
467 assert(I->hasUnsafeAlgebra() && "Should be in unsafe mode");
469 // Currently we are not able to handle vector type.
470 if (I->getType()->isVectorTy())
473 assert((I->getOpcode() == Instruction::FAdd ||
474 I->getOpcode() == Instruction::FSub) && "Expect add/sub");
476 // Save the instruction before calling other member-functions.
479 FAddend Opnd0, Opnd1, Opnd0_0, Opnd0_1, Opnd1_0, Opnd1_1;
481 unsigned OpndNum = FAddend::drillValueDownOneStep(I, Opnd0, Opnd1);
483 // Step 1: Expand the 1st addend into Opnd0_0 and Opnd0_1.
484 unsigned Opnd0_ExpNum = 0;
485 unsigned Opnd1_ExpNum = 0;
487 if (!Opnd0.isConstant())
488 Opnd0_ExpNum = Opnd0.drillAddendDownOneStep(Opnd0_0, Opnd0_1);
490 // Step 2: Expand the 2nd addend into Opnd1_0 and Opnd1_1.
491 if (OpndNum == 2 && !Opnd1.isConstant())
492 Opnd1_ExpNum = Opnd1.drillAddendDownOneStep(Opnd1_0, Opnd1_1);
494 // Step 3: Try to optimize Opnd0_0 + Opnd0_1 + Opnd1_0 + Opnd1_1
495 if (Opnd0_ExpNum && Opnd1_ExpNum) {
497 AllOpnds.push_back(&Opnd0_0);
498 AllOpnds.push_back(&Opnd1_0);
499 if (Opnd0_ExpNum == 2)
500 AllOpnds.push_back(&Opnd0_1);
501 if (Opnd1_ExpNum == 2)
502 AllOpnds.push_back(&Opnd1_1);
504 // Compute instruction quota. We should save at least one instruction.
505 unsigned InstQuota = 0;
507 Value *V0 = I->getOperand(0);
508 Value *V1 = I->getOperand(1);
509 InstQuota = ((!isa<Constant>(V0) && V0->hasOneUse()) &&
510 (!isa<Constant>(V1) && V1->hasOneUse())) ? 2 : 1;
512 if (Value *R = simplifyFAdd(AllOpnds, InstQuota))
517 // The input instruction is : "I=0.0 +/- V". If the "V" were able to be
518 // splitted into two addends, say "V = X - Y", the instruction would have
519 // been optimized into "I = Y - X" in the previous steps.
521 const FAddendCoef &CE = Opnd0.getCoef();
522 return CE.isOne() ? Opnd0.getSymVal() : 0;
525 // step 4: Try to optimize Opnd0 + Opnd1_0 [+ Opnd1_1]
528 AllOpnds.push_back(&Opnd0);
529 AllOpnds.push_back(&Opnd1_0);
530 if (Opnd1_ExpNum == 2)
531 AllOpnds.push_back(&Opnd1_1);
533 if (Value *R = simplifyFAdd(AllOpnds, 1))
537 // step 5: Try to optimize Opnd1 + Opnd0_0 [+ Opnd0_1]
540 AllOpnds.push_back(&Opnd1);
541 AllOpnds.push_back(&Opnd0_0);
542 if (Opnd0_ExpNum == 2)
543 AllOpnds.push_back(&Opnd0_1);
545 if (Value *R = simplifyFAdd(AllOpnds, 1))
549 // step 6: Try factorization as the last resort,
550 return performFactorization(I);
553 Value *FAddCombine::simplifyFAdd(AddendVect& Addends, unsigned InstrQuota) {
555 unsigned AddendNum = Addends.size();
556 assert(AddendNum <= 4 && "Too many addends");
558 // For saving intermediate results;
559 unsigned NextTmpIdx = 0;
560 FAddend TmpResult[3];
562 // Points to the constant addend of the resulting simplified expression.
563 // If the resulting expr has constant-addend, this constant-addend is
564 // desirable to reside at the top of the resulting expression tree. Placing
565 // constant close to supper-expr(s) will potentially reveal some optimization
566 // opportunities in super-expr(s).
568 const FAddend *ConstAdd = 0;
570 // Simplified addends are placed <SimpVect>.
573 // The outer loop works on one symbolic-value at a time. Suppose the input
574 // addends are : <a1, x>, <b1, y>, <a2, x>, <c1, z>, <b2, y>, ...
575 // The symbolic-values will be processed in this order: x, y, z.
577 for (unsigned SymIdx = 0; SymIdx < AddendNum; SymIdx++) {
579 const FAddend *ThisAddend = Addends[SymIdx];
581 // This addend was processed before.
585 Value *Val = ThisAddend->getSymVal();
586 unsigned StartIdx = SimpVect.size();
587 SimpVect.push_back(ThisAddend);
589 // The inner loop collects addends sharing same symbolic-value, and these
590 // addends will be later on folded into a single addend. Following above
591 // example, if the symbolic value "y" is being processed, the inner loop
592 // will collect two addends "<b1,y>" and "<b2,Y>". These two addends will
593 // be later on folded into "<b1+b2, y>".
595 for (unsigned SameSymIdx = SymIdx + 1;
596 SameSymIdx < AddendNum; SameSymIdx++) {
597 const FAddend *T = Addends[SameSymIdx];
598 if (T && T->getSymVal() == Val) {
599 // Set null such that next iteration of the outer loop will not process
600 // this addend again.
601 Addends[SameSymIdx] = 0;
602 SimpVect.push_back(T);
606 // If multiple addends share same symbolic value, fold them together.
607 if (StartIdx + 1 != SimpVect.size()) {
608 FAddend &R = TmpResult[NextTmpIdx ++];
609 R = *SimpVect[StartIdx];
610 for (unsigned Idx = StartIdx + 1; Idx < SimpVect.size(); Idx++)
613 // Pop all addends being folded and push the resulting folded addend.
614 SimpVect.resize(StartIdx);
617 SimpVect.push_back(&R);
620 // Don't push constant addend at this time. It will be the last element
627 assert((NextTmpIdx <= sizeof(TmpResult)/sizeof(TmpResult[0]) + 1) &&
628 "out-of-bound access");
631 SimpVect.push_back(ConstAdd);
634 if (!SimpVect.empty())
635 Result = createNaryFAdd(SimpVect, InstrQuota);
637 // The addition is folded to 0.0.
638 Result = ConstantFP::get(Instr->getType(), 0.0);
644 Value *FAddCombine::createNaryFAdd
645 (const AddendVect &Opnds, unsigned InstrQuota) {
646 assert(!Opnds.empty() && "Expect at least one addend");
648 // Step 1: Check if the # of instructions needed exceeds the quota.
650 unsigned InstrNeeded = calcInstrNumber(Opnds);
651 if (InstrNeeded > InstrQuota)
656 // step 2: Emit the N-ary addition.
657 // Note that at most three instructions are involved in Fadd-InstCombine: the
658 // addition in question, and at most two neighboring instructions.
659 // The resulting optimized addition should have at least one less instruction
660 // than the original addition expression tree. This implies that the resulting
661 // N-ary addition has at most two instructions, and we don't need to worry
662 // about tree-height when constructing the N-ary addition.
665 bool LastValNeedNeg = false;
667 // Iterate the addends, creating fadd/fsub using adjacent two addends.
668 for (AddendVect::const_iterator I = Opnds.begin(), E = Opnds.end();
671 Value *V = createAddendVal(**I, NeedNeg);
674 LastValNeedNeg = NeedNeg;
678 if (LastValNeedNeg == NeedNeg) {
679 LastVal = createFAdd(LastVal, V);
684 LastVal = createFSub(V, LastVal);
686 LastVal = createFSub(LastVal, V);
688 LastValNeedNeg = false;
691 if (LastValNeedNeg) {
692 LastVal = createFNeg(LastVal);
696 assert(CreateInstrNum == InstrNeeded &&
697 "Inconsistent in instruction numbers");
703 Value *FAddCombine::createFSub
704 (Value *Opnd0, Value *Opnd1) {
705 Value *V = Builder->CreateFSub(Opnd0, Opnd1);
706 if (Instruction *I = dyn_cast<Instruction>(V))
707 createInstPostProc(I);
711 Value *FAddCombine::createFNeg(Value *V) {
712 Value *Zero = cast<Value>(ConstantFP::get(V->getType(), 0.0));
713 return createFSub(Zero, V);
716 Value *FAddCombine::createFAdd
717 (Value *Opnd0, Value *Opnd1) {
718 Value *V = Builder->CreateFAdd(Opnd0, Opnd1);
719 if (Instruction *I = dyn_cast<Instruction>(V))
720 createInstPostProc(I);
724 Value *FAddCombine::createFMul(Value *Opnd0, Value *Opnd1) {
725 Value *V = Builder->CreateFMul(Opnd0, Opnd1);
726 if (Instruction *I = dyn_cast<Instruction>(V))
727 createInstPostProc(I);
731 Value *FAddCombine::createFDiv(Value *Opnd0, Value *Opnd1) {
732 Value *V = Builder->CreateFDiv(Opnd0, Opnd1);
733 if (Instruction *I = dyn_cast<Instruction>(V))
734 createInstPostProc(I);
738 void FAddCombine::createInstPostProc(Instruction *NewInstr) {
739 NewInstr->setDebugLoc(Instr->getDebugLoc());
741 // Keep track of the number of instruction created.
744 // Propagate fast-math flags
745 NewInstr->setFastMathFlags(Instr->getFastMathFlags());
748 // Return the number of instruction needed to emit the N-ary addition.
749 // NOTE: Keep this function in sync with createAddendVal().
750 unsigned FAddCombine::calcInstrNumber(const AddendVect &Opnds) {
751 unsigned OpndNum = Opnds.size();
752 unsigned InstrNeeded = OpndNum - 1;
754 // The number of addends in the form of "(-1)*x".
755 unsigned NegOpndNum = 0;
757 // Adjust the number of instructions needed to emit the N-ary add.
758 for (AddendVect::const_iterator I = Opnds.begin(), E = Opnds.end();
760 const FAddend *Opnd = *I;
761 if (Opnd->isConstant())
764 const FAddendCoef &CE = Opnd->getCoef();
765 if (CE.isMinusOne() || CE.isMinusTwo())
768 // Let the addend be "c * x". If "c == +/-1", the value of the addend
769 // is immediately available; otherwise, it needs exactly one instruction
770 // to evaluate the value.
771 if (!CE.isMinusOne() && !CE.isOne())
774 if (NegOpndNum == OpndNum)
779 // Input Addend Value NeedNeg(output)
780 // ================================================================
781 // Constant C C false
782 // <+/-1, V> V coefficient is -1
783 // <2/-2, V> "fadd V, V" coefficient is -2
784 // <C, V> "fmul V, C" false
786 // NOTE: Keep this function in sync with FAddCombine::calcInstrNumber.
787 Value *FAddCombine::createAddendVal
788 (const FAddend &Opnd, bool &NeedNeg) {
789 const FAddendCoef &Coeff = Opnd.getCoef();
791 if (Opnd.isConstant()) {
793 return Coeff.getValue(Instr->getType());
796 Value *OpndVal = Opnd.getSymVal();
798 if (Coeff.isMinusOne() || Coeff.isOne()) {
799 NeedNeg = Coeff.isMinusOne();
803 if (Coeff.isTwo() || Coeff.isMinusTwo()) {
804 NeedNeg = Coeff.isMinusTwo();
805 return createFAdd(OpndVal, OpndVal);
809 return createFMul(OpndVal, Coeff.getValue(Instr->getType()));
812 /// AddOne - Add one to a ConstantInt.
813 static Constant *AddOne(Constant *C) {
814 return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1));
817 /// SubOne - Subtract one from a ConstantInt.
818 static Constant *SubOne(ConstantInt *C) {
819 return ConstantInt::get(C->getContext(), C->getValue()-1);
823 // dyn_castFoldableMul - If this value is a multiply that can be folded into
824 // other computations (because it has a constant operand), return the
825 // non-constant operand of the multiply, and set CST to point to the multiplier.
826 // Otherwise, return null.
828 static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
829 if (!V->hasOneUse() || !V->getType()->isIntegerTy())
832 Instruction *I = dyn_cast<Instruction>(V);
833 if (I == 0) return 0;
835 if (I->getOpcode() == Instruction::Mul)
836 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
837 return I->getOperand(0);
838 if (I->getOpcode() == Instruction::Shl)
839 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
840 // The multiplier is really 1 << CST.
841 uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
842 uint32_t CSTVal = CST->getLimitedValue(BitWidth);
843 CST = ConstantInt::get(V->getType()->getContext(),
844 APInt(BitWidth, 1).shl(CSTVal));
845 return I->getOperand(0);
851 /// WillNotOverflowSignedAdd - Return true if we can prove that:
852 /// (sext (add LHS, RHS)) === (add (sext LHS), (sext RHS))
853 /// This basically requires proving that the add in the original type would not
854 /// overflow to change the sign bit or have a carry out.
855 bool InstCombiner::WillNotOverflowSignedAdd(Value *LHS, Value *RHS) {
856 // There are different heuristics we can use for this. Here are some simple
859 // Add has the property that adding any two 2's complement numbers can only
860 // have one carry bit which can change a sign. As such, if LHS and RHS each
861 // have at least two sign bits, we know that the addition of the two values
862 // will sign extend fine.
863 if (ComputeNumSignBits(LHS) > 1 && ComputeNumSignBits(RHS) > 1)
867 // If one of the operands only has one non-zero bit, and if the other operand
868 // has a known-zero bit in a more significant place than it (not including the
869 // sign bit) the ripple may go up to and fill the zero, but won't change the
870 // sign. For example, (X & ~4) + 1.
877 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
878 bool Changed = SimplifyAssociativeOrCommutative(I);
879 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
881 if (Value *V = SimplifyAddInst(LHS, RHS, I.hasNoSignedWrap(),
882 I.hasNoUnsignedWrap(), TD))
883 return ReplaceInstUsesWith(I, V);
885 // (A*B)+(A*C) -> A*(B+C) etc
886 if (Value *V = SimplifyUsingDistributiveLaws(I))
887 return ReplaceInstUsesWith(I, V);
889 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
890 // X + (signbit) --> X ^ signbit
891 const APInt &Val = CI->getValue();
893 return BinaryOperator::CreateXor(LHS, RHS);
895 // See if SimplifyDemandedBits can simplify this. This handles stuff like
896 // (X & 254)+1 -> (X&254)|1
897 if (SimplifyDemandedInstructionBits(I))
900 // zext(bool) + C -> bool ? C + 1 : C
901 if (ZExtInst *ZI = dyn_cast<ZExtInst>(LHS))
902 if (ZI->getSrcTy()->isIntegerTy(1))
903 return SelectInst::Create(ZI->getOperand(0), AddOne(CI), CI);
905 Value *XorLHS = 0; ConstantInt *XorRHS = 0;
906 if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
907 uint32_t TySizeBits = I.getType()->getScalarSizeInBits();
908 const APInt &RHSVal = CI->getValue();
909 unsigned ExtendAmt = 0;
910 // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
911 // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
912 if (XorRHS->getValue() == -RHSVal) {
913 if (RHSVal.isPowerOf2())
914 ExtendAmt = TySizeBits - RHSVal.logBase2() - 1;
915 else if (XorRHS->getValue().isPowerOf2())
916 ExtendAmt = TySizeBits - XorRHS->getValue().logBase2() - 1;
920 APInt Mask = APInt::getHighBitsSet(TySizeBits, ExtendAmt);
921 if (!MaskedValueIsZero(XorLHS, Mask))
926 Constant *ShAmt = ConstantInt::get(I.getType(), ExtendAmt);
927 Value *NewShl = Builder->CreateShl(XorLHS, ShAmt, "sext");
928 return BinaryOperator::CreateAShr(NewShl, ShAmt);
931 // If this is a xor that was canonicalized from a sub, turn it back into
932 // a sub and fuse this add with it.
933 if (LHS->hasOneUse() && (XorRHS->getValue()+1).isPowerOf2()) {
934 IntegerType *IT = cast<IntegerType>(I.getType());
935 APInt LHSKnownOne(IT->getBitWidth(), 0);
936 APInt LHSKnownZero(IT->getBitWidth(), 0);
937 ComputeMaskedBits(XorLHS, LHSKnownZero, LHSKnownOne);
938 if ((XorRHS->getValue() | LHSKnownZero).isAllOnesValue())
939 return BinaryOperator::CreateSub(ConstantExpr::getAdd(XorRHS, CI),
945 if (isa<Constant>(RHS) && isa<PHINode>(LHS))
946 if (Instruction *NV = FoldOpIntoPhi(I))
949 if (I.getType()->isIntegerTy(1))
950 return BinaryOperator::CreateXor(LHS, RHS);
954 BinaryOperator *New =
955 BinaryOperator::CreateShl(LHS, ConstantInt::get(I.getType(), 1));
956 New->setHasNoSignedWrap(I.hasNoSignedWrap());
957 New->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
962 // -A + -B --> -(A + B)
963 if (Value *LHSV = dyn_castNegVal(LHS)) {
964 if (!isa<Constant>(RHS))
965 if (Value *RHSV = dyn_castNegVal(RHS)) {
966 Value *NewAdd = Builder->CreateAdd(LHSV, RHSV, "sum");
967 return BinaryOperator::CreateNeg(NewAdd);
970 return BinaryOperator::CreateSub(RHS, LHSV);
974 if (!isa<Constant>(RHS))
975 if (Value *V = dyn_castNegVal(RHS))
976 return BinaryOperator::CreateSub(LHS, V);
980 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
981 if (X == RHS) // X*C + X --> X * (C+1)
982 return BinaryOperator::CreateMul(RHS, AddOne(C2));
984 // X*C1 + X*C2 --> X * (C1+C2)
986 if (X == dyn_castFoldableMul(RHS, C1))
987 return BinaryOperator::CreateMul(X, ConstantExpr::getAdd(C1, C2));
990 // X + X*C --> X * (C+1)
991 if (dyn_castFoldableMul(RHS, C2) == LHS)
992 return BinaryOperator::CreateMul(LHS, AddOne(C2));
994 // A+B --> A|B iff A and B have no bits set in common.
995 if (IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
996 APInt LHSKnownOne(IT->getBitWidth(), 0);
997 APInt LHSKnownZero(IT->getBitWidth(), 0);
998 ComputeMaskedBits(LHS, LHSKnownZero, LHSKnownOne);
999 if (LHSKnownZero != 0) {
1000 APInt RHSKnownOne(IT->getBitWidth(), 0);
1001 APInt RHSKnownZero(IT->getBitWidth(), 0);
1002 ComputeMaskedBits(RHS, RHSKnownZero, RHSKnownOne);
1004 // No bits in common -> bitwise or.
1005 if ((LHSKnownZero|RHSKnownZero).isAllOnesValue())
1006 return BinaryOperator::CreateOr(LHS, RHS);
1010 // W*X + Y*Z --> W * (X+Z) iff W == Y
1012 Value *W, *X, *Y, *Z;
1013 if (match(LHS, m_Mul(m_Value(W), m_Value(X))) &&
1014 match(RHS, m_Mul(m_Value(Y), m_Value(Z)))) {
1018 } else if (Y == X) {
1020 } else if (X == Z) {
1027 Value *NewAdd = Builder->CreateAdd(X, Z, LHS->getName());
1028 return BinaryOperator::CreateMul(W, NewAdd);
1033 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
1035 if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X
1036 return BinaryOperator::CreateSub(SubOne(CRHS), X);
1038 // (X & FF00) + xx00 -> (X+xx00) & FF00
1039 if (LHS->hasOneUse() &&
1040 match(LHS, m_And(m_Value(X), m_ConstantInt(C2))) &&
1041 CRHS->getValue() == (CRHS->getValue() & C2->getValue())) {
1042 // See if all bits from the first bit set in the Add RHS up are included
1043 // in the mask. First, get the rightmost bit.
1044 const APInt &AddRHSV = CRHS->getValue();
1046 // Form a mask of all bits from the lowest bit added through the top.
1047 APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1));
1049 // See if the and mask includes all of these bits.
1050 APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue());
1052 if (AddRHSHighBits == AddRHSHighBitsAnd) {
1053 // Okay, the xform is safe. Insert the new add pronto.
1054 Value *NewAdd = Builder->CreateAdd(X, CRHS, LHS->getName());
1055 return BinaryOperator::CreateAnd(NewAdd, C2);
1059 // Try to fold constant add into select arguments.
1060 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
1061 if (Instruction *R = FoldOpIntoSelect(I, SI))
1065 // add (select X 0 (sub n A)) A --> select X A n
1067 SelectInst *SI = dyn_cast<SelectInst>(LHS);
1070 SI = dyn_cast<SelectInst>(RHS);
1073 if (SI && SI->hasOneUse()) {
1074 Value *TV = SI->getTrueValue();
1075 Value *FV = SI->getFalseValue();
1078 // Can we fold the add into the argument of the select?
1079 // We check both true and false select arguments for a matching subtract.
1080 if (match(FV, m_Zero()) && match(TV, m_Sub(m_Value(N), m_Specific(A))))
1081 // Fold the add into the true select value.
1082 return SelectInst::Create(SI->getCondition(), N, A);
1084 if (match(TV, m_Zero()) && match(FV, m_Sub(m_Value(N), m_Specific(A))))
1085 // Fold the add into the false select value.
1086 return SelectInst::Create(SI->getCondition(), A, N);
1090 // Check for (add (sext x), y), see if we can merge this into an
1091 // integer add followed by a sext.
1092 if (SExtInst *LHSConv = dyn_cast<SExtInst>(LHS)) {
1093 // (add (sext x), cst) --> (sext (add x, cst'))
1094 if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
1096 ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType());
1097 if (LHSConv->hasOneUse() &&
1098 ConstantExpr::getSExt(CI, I.getType()) == RHSC &&
1099 WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
1100 // Insert the new, smaller add.
1101 Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
1103 return new SExtInst(NewAdd, I.getType());
1107 // (add (sext x), (sext y)) --> (sext (add int x, y))
1108 if (SExtInst *RHSConv = dyn_cast<SExtInst>(RHS)) {
1109 // Only do this if x/y have the same type, if at last one of them has a
1110 // single use (so we don't increase the number of sexts), and if the
1111 // integer add will not overflow.
1112 if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
1113 (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
1114 WillNotOverflowSignedAdd(LHSConv->getOperand(0),
1115 RHSConv->getOperand(0))) {
1116 // Insert the new integer add.
1117 Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
1118 RHSConv->getOperand(0), "addconv");
1119 return new SExtInst(NewAdd, I.getType());
1124 // Check for (x & y) + (x ^ y)
1126 Value *A = 0, *B = 0;
1127 if (match(RHS, m_Xor(m_Value(A), m_Value(B))) &&
1128 (match(LHS, m_And(m_Specific(A), m_Specific(B))) ||
1129 match(LHS, m_And(m_Specific(B), m_Specific(A)))))
1130 return BinaryOperator::CreateOr(A, B);
1132 if (match(LHS, m_Xor(m_Value(A), m_Value(B))) &&
1133 (match(RHS, m_And(m_Specific(A), m_Specific(B))) ||
1134 match(RHS, m_And(m_Specific(B), m_Specific(A)))))
1135 return BinaryOperator::CreateOr(A, B);
1138 return Changed ? &I : 0;
1141 Instruction *InstCombiner::visitFAdd(BinaryOperator &I) {
1142 bool Changed = SimplifyAssociativeOrCommutative(I);
1143 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
1145 if (Value *V = SimplifyFAddInst(LHS, RHS, I.getFastMathFlags(), TD))
1146 return ReplaceInstUsesWith(I, V);
1148 if (isa<Constant>(RHS) && isa<PHINode>(LHS))
1149 if (Instruction *NV = FoldOpIntoPhi(I))
1153 // -A + -B --> -(A + B)
1154 if (Value *LHSV = dyn_castFNegVal(LHS))
1155 return BinaryOperator::CreateFSub(RHS, LHSV);
1158 if (!isa<Constant>(RHS))
1159 if (Value *V = dyn_castFNegVal(RHS))
1160 return BinaryOperator::CreateFSub(LHS, V);
1162 // Check for (fadd double (sitofp x), y), see if we can merge this into an
1163 // integer add followed by a promotion.
1164 if (SIToFPInst *LHSConv = dyn_cast<SIToFPInst>(LHS)) {
1165 // (fadd double (sitofp x), fpcst) --> (sitofp (add int x, intcst))
1166 // ... if the constant fits in the integer value. This is useful for things
1167 // like (double)(x & 1234) + 4.0 -> (double)((X & 1234)+4) which no longer
1168 // requires a constant pool load, and generally allows the add to be better
1170 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) {
1172 ConstantExpr::getFPToSI(CFP, LHSConv->getOperand(0)->getType());
1173 if (LHSConv->hasOneUse() &&
1174 ConstantExpr::getSIToFP(CI, I.getType()) == CFP &&
1175 WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
1176 // Insert the new integer add.
1177 Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
1179 return new SIToFPInst(NewAdd, I.getType());
1183 // (fadd double (sitofp x), (sitofp y)) --> (sitofp (add int x, y))
1184 if (SIToFPInst *RHSConv = dyn_cast<SIToFPInst>(RHS)) {
1185 // Only do this if x/y have the same type, if at last one of them has a
1186 // single use (so we don't increase the number of int->fp conversions),
1187 // and if the integer add will not overflow.
1188 if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
1189 (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
1190 WillNotOverflowSignedAdd(LHSConv->getOperand(0),
1191 RHSConv->getOperand(0))) {
1192 // Insert the new integer add.
1193 Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0),
1194 RHSConv->getOperand(0),"addconv");
1195 return new SIToFPInst(NewAdd, I.getType());
1200 if (I.hasUnsafeAlgebra()) {
1201 if (Value *V = FAddCombine(Builder).simplify(&I))
1202 return ReplaceInstUsesWith(I, V);
1205 return Changed ? &I : 0;
1209 /// Optimize pointer differences into the same array into a size. Consider:
1210 /// &A[10] - &A[0]: we should compile this to "10". LHS/RHS are the pointer
1211 /// operands to the ptrtoint instructions for the LHS/RHS of the subtract.
1213 Value *InstCombiner::OptimizePointerDifference(Value *LHS, Value *RHS,
1215 assert(TD && "Must have target data info for this");
1217 // If LHS is a gep based on RHS or RHS is a gep based on LHS, we can optimize
1219 bool Swapped = false;
1220 GEPOperator *GEP1 = 0, *GEP2 = 0;
1222 // For now we require one side to be the base pointer "A" or a constant
1223 // GEP derived from it.
1224 if (GEPOperator *LHSGEP = dyn_cast<GEPOperator>(LHS)) {
1226 if (LHSGEP->getOperand(0) == RHS) {
1229 } else if (GEPOperator *RHSGEP = dyn_cast<GEPOperator>(RHS)) {
1230 // (gep X, ...) - (gep X, ...)
1231 if (LHSGEP->getOperand(0)->stripPointerCasts() ==
1232 RHSGEP->getOperand(0)->stripPointerCasts()) {
1240 if (GEPOperator *RHSGEP = dyn_cast<GEPOperator>(RHS)) {
1242 if (RHSGEP->getOperand(0) == LHS) {
1245 } else if (GEPOperator *LHSGEP = dyn_cast<GEPOperator>(LHS)) {
1246 // (gep X, ...) - (gep X, ...)
1247 if (RHSGEP->getOperand(0)->stripPointerCasts() ==
1248 LHSGEP->getOperand(0)->stripPointerCasts()) {
1256 // Avoid duplicating the arithmetic if GEP2 has non-constant indices and
1259 (GEP2 != 0 && !GEP2->hasAllConstantIndices() && !GEP2->hasOneUse()))
1262 // Emit the offset of the GEP and an intptr_t.
1263 Value *Result = EmitGEPOffset(GEP1);
1265 // If we had a constant expression GEP on the other side offsetting the
1266 // pointer, subtract it from the offset we have.
1268 Value *Offset = EmitGEPOffset(GEP2);
1269 Result = Builder->CreateSub(Result, Offset);
1272 // If we have p - gep(p, ...) then we have to negate the result.
1274 Result = Builder->CreateNeg(Result, "diff.neg");
1276 return Builder->CreateIntCast(Result, Ty, true);
1280 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
1281 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1283 if (Value *V = SimplifySubInst(Op0, Op1, I.hasNoSignedWrap(),
1284 I.hasNoUnsignedWrap(), TD))
1285 return ReplaceInstUsesWith(I, V);
1287 // (A*B)-(A*C) -> A*(B-C) etc
1288 if (Value *V = SimplifyUsingDistributiveLaws(I))
1289 return ReplaceInstUsesWith(I, V);
1291 // If this is a 'B = x-(-A)', change to B = x+A. This preserves NSW/NUW.
1292 if (Value *V = dyn_castNegVal(Op1)) {
1293 BinaryOperator *Res = BinaryOperator::CreateAdd(Op0, V);
1294 Res->setHasNoSignedWrap(I.hasNoSignedWrap());
1295 Res->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
1299 if (I.getType()->isIntegerTy(1))
1300 return BinaryOperator::CreateXor(Op0, Op1);
1302 // Replace (-1 - A) with (~A).
1303 if (match(Op0, m_AllOnes()))
1304 return BinaryOperator::CreateNot(Op1);
1306 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
1307 // C - ~X == X + (1+C)
1309 if (match(Op1, m_Not(m_Value(X))))
1310 return BinaryOperator::CreateAdd(X, AddOne(C));
1312 // -(X >>u 31) -> (X >>s 31)
1313 // -(X >>s 31) -> (X >>u 31)
1315 Value *X; ConstantInt *CI;
1316 if (match(Op1, m_LShr(m_Value(X), m_ConstantInt(CI))) &&
1317 // Verify we are shifting out everything but the sign bit.
1318 CI->getValue() == I.getType()->getPrimitiveSizeInBits()-1)
1319 return BinaryOperator::CreateAShr(X, CI);
1321 if (match(Op1, m_AShr(m_Value(X), m_ConstantInt(CI))) &&
1322 // Verify we are shifting out everything but the sign bit.
1323 CI->getValue() == I.getType()->getPrimitiveSizeInBits()-1)
1324 return BinaryOperator::CreateLShr(X, CI);
1327 // Try to fold constant sub into select arguments.
1328 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1329 if (Instruction *R = FoldOpIntoSelect(I, SI))
1332 // C-(X+C2) --> (C-C2)-X
1334 if (match(Op1, m_Add(m_Value(X), m_ConstantInt(C2))))
1335 return BinaryOperator::CreateSub(ConstantExpr::getSub(C, C2), X);
1337 if (SimplifyDemandedInstructionBits(I))
1340 // Fold (sub 0, (zext bool to B)) --> (sext bool to B)
1341 if (C->isZero() && match(Op1, m_ZExt(m_Value(X))))
1342 if (X->getType()->isIntegerTy(1))
1343 return CastInst::CreateSExtOrBitCast(X, Op1->getType());
1345 // Fold (sub 0, (sext bool to B)) --> (zext bool to B)
1346 if (C->isZero() && match(Op1, m_SExt(m_Value(X))))
1347 if (X->getType()->isIntegerTy(1))
1348 return CastInst::CreateZExtOrBitCast(X, Op1->getType());
1353 // X-(X+Y) == -Y X-(Y+X) == -Y
1354 if (match(Op1, m_Add(m_Specific(Op0), m_Value(Y))) ||
1355 match(Op1, m_Add(m_Value(Y), m_Specific(Op0))))
1356 return BinaryOperator::CreateNeg(Y);
1359 if (match(Op0, m_Sub(m_Specific(Op1), m_Value(Y))))
1360 return BinaryOperator::CreateNeg(Y);
1363 if (Op1->hasOneUse()) {
1364 Value *X = 0, *Y = 0, *Z = 0;
1366 ConstantInt *CI = 0;
1368 // (X - (Y - Z)) --> (X + (Z - Y)).
1369 if (match(Op1, m_Sub(m_Value(Y), m_Value(Z))))
1370 return BinaryOperator::CreateAdd(Op0,
1371 Builder->CreateSub(Z, Y, Op1->getName()));
1373 // (X - (X & Y)) --> (X & ~Y)
1375 if (match(Op1, m_And(m_Value(Y), m_Specific(Op0))) ||
1376 match(Op1, m_And(m_Specific(Op0), m_Value(Y))))
1377 return BinaryOperator::CreateAnd(Op0,
1378 Builder->CreateNot(Y, Y->getName() + ".not"));
1380 // 0 - (X sdiv C) -> (X sdiv -C)
1381 if (match(Op1, m_SDiv(m_Value(X), m_Constant(C))) &&
1382 match(Op0, m_Zero()))
1383 return BinaryOperator::CreateSDiv(X, ConstantExpr::getNeg(C));
1385 // 0 - (X << Y) -> (-X << Y) when X is freely negatable.
1386 if (match(Op1, m_Shl(m_Value(X), m_Value(Y))) && match(Op0, m_Zero()))
1387 if (Value *XNeg = dyn_castNegVal(X))
1388 return BinaryOperator::CreateShl(XNeg, Y);
1390 // X - X*C --> X * (1-C)
1391 if (match(Op1, m_Mul(m_Specific(Op0), m_ConstantInt(CI)))) {
1392 Constant *CP1 = ConstantExpr::getSub(ConstantInt::get(I.getType(),1), CI);
1393 return BinaryOperator::CreateMul(Op0, CP1);
1396 // X - X<<C --> X * (1-(1<<C))
1397 if (match(Op1, m_Shl(m_Specific(Op0), m_ConstantInt(CI)))) {
1398 Constant *One = ConstantInt::get(I.getType(), 1);
1399 C = ConstantExpr::getSub(One, ConstantExpr::getShl(One, CI));
1400 return BinaryOperator::CreateMul(Op0, C);
1403 // X - A*-B -> X + A*B
1404 // X - -A*B -> X + A*B
1406 if (match(Op1, m_Mul(m_Value(A), m_Neg(m_Value(B)))) ||
1407 match(Op1, m_Mul(m_Neg(m_Value(A)), m_Value(B))))
1408 return BinaryOperator::CreateAdd(Op0, Builder->CreateMul(A, B));
1410 // X - A*CI -> X + A*-CI
1411 // X - CI*A -> X + A*-CI
1412 if (match(Op1, m_Mul(m_Value(A), m_ConstantInt(CI))) ||
1413 match(Op1, m_Mul(m_ConstantInt(CI), m_Value(A)))) {
1414 Value *NewMul = Builder->CreateMul(A, ConstantExpr::getNeg(CI));
1415 return BinaryOperator::CreateAdd(Op0, NewMul);
1420 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
1421 if (X == Op1) // X*C - X --> X * (C-1)
1422 return BinaryOperator::CreateMul(Op1, SubOne(C1));
1424 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
1425 if (X == dyn_castFoldableMul(Op1, C2))
1426 return BinaryOperator::CreateMul(X, ConstantExpr::getSub(C1, C2));
1429 // Optimize pointer differences into the same array into a size. Consider:
1430 // &A[10] - &A[0]: we should compile this to "10".
1432 Value *LHSOp, *RHSOp;
1433 if (match(Op0, m_PtrToInt(m_Value(LHSOp))) &&
1434 match(Op1, m_PtrToInt(m_Value(RHSOp))))
1435 if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
1436 return ReplaceInstUsesWith(I, Res);
1438 // trunc(p)-trunc(q) -> trunc(p-q)
1439 if (match(Op0, m_Trunc(m_PtrToInt(m_Value(LHSOp)))) &&
1440 match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp)))))
1441 if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
1442 return ReplaceInstUsesWith(I, Res);
1448 Instruction *InstCombiner::visitFSub(BinaryOperator &I) {
1449 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1451 if (Value *V = SimplifyFSubInst(Op0, Op1, I.getFastMathFlags(), TD))
1452 return ReplaceInstUsesWith(I, V);
1454 // If this is a 'B = x-(-A)', change to B = x+A...
1455 if (Value *V = dyn_castFNegVal(Op1))
1456 return BinaryOperator::CreateFAdd(Op0, V);
1458 if (I.hasUnsafeAlgebra()) {
1459 if (Value *V = FAddCombine(Builder).simplify(&I))
1460 return ReplaceInstUsesWith(I, V);