1 //===- InstCombineMulDivRem.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 mul, fmul, sdiv, udiv, fdiv,
13 //===----------------------------------------------------------------------===//
15 #include "InstCombine.h"
16 #include "llvm/Analysis/InstructionSimplify.h"
17 #include "llvm/IR/IntrinsicInst.h"
18 #include "llvm/IR/PatternMatch.h"
20 using namespace PatternMatch;
22 #define DEBUG_TYPE "instcombine"
25 /// simplifyValueKnownNonZero - The specific integer value is used in a context
26 /// where it is known to be non-zero. If this allows us to simplify the
27 /// computation, do so and return the new operand, otherwise return null.
28 static Value *simplifyValueKnownNonZero(Value *V, InstCombiner &IC) {
29 // If V has multiple uses, then we would have to do more analysis to determine
30 // if this is safe. For example, the use could be in dynamically unreached
32 if (!V->hasOneUse()) return nullptr;
34 bool MadeChange = false;
36 // ((1 << A) >>u B) --> (1 << (A-B))
37 // Because V cannot be zero, we know that B is less than A.
38 Value *A = nullptr, *B = nullptr, *PowerOf2 = nullptr;
39 if (match(V, m_LShr(m_OneUse(m_Shl(m_Value(PowerOf2), m_Value(A))),
41 // The "1" can be any value known to be a power of 2.
42 isKnownToBeAPowerOfTwo(PowerOf2)) {
43 A = IC.Builder->CreateSub(A, B);
44 return IC.Builder->CreateShl(PowerOf2, A);
47 // (PowerOfTwo >>u B) --> isExact since shifting out the result would make it
48 // inexact. Similarly for <<.
49 if (BinaryOperator *I = dyn_cast<BinaryOperator>(V))
50 if (I->isLogicalShift() && isKnownToBeAPowerOfTwo(I->getOperand(0))) {
51 // We know that this is an exact/nuw shift and that the input is a
52 // non-zero context as well.
53 if (Value *V2 = simplifyValueKnownNonZero(I->getOperand(0), IC)) {
58 if (I->getOpcode() == Instruction::LShr && !I->isExact()) {
63 if (I->getOpcode() == Instruction::Shl && !I->hasNoUnsignedWrap()) {
64 I->setHasNoUnsignedWrap();
69 // TODO: Lots more we could do here:
70 // If V is a phi node, we can call this on each of its operands.
71 // "select cond, X, 0" can simplify to "X".
73 return MadeChange ? V : nullptr;
77 /// MultiplyOverflows - True if the multiply can not be expressed in an int
79 static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
80 uint32_t W = C1->getBitWidth();
81 APInt LHSExt = C1->getValue(), RHSExt = C2->getValue();
83 LHSExt = LHSExt.sext(W * 2);
84 RHSExt = RHSExt.sext(W * 2);
86 LHSExt = LHSExt.zext(W * 2);
87 RHSExt = RHSExt.zext(W * 2);
90 APInt MulExt = LHSExt * RHSExt;
93 return MulExt.ugt(APInt::getLowBitsSet(W * 2, W));
95 APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
96 APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
97 return MulExt.slt(Min) || MulExt.sgt(Max);
100 /// \brief A helper routine of InstCombiner::visitMul().
102 /// If C is a vector of known powers of 2, then this function returns
103 /// a new vector obtained from C replacing each element with its logBase2.
104 /// Return a null pointer otherwise.
105 static Constant *getLogBase2Vector(ConstantDataVector *CV) {
107 SmallVector<Constant *, 4> Elts;
109 for (unsigned I = 0, E = CV->getNumElements(); I != E; ++I) {
110 Constant *Elt = CV->getElementAsConstant(I);
111 if (!match(Elt, m_APInt(IVal)) || !IVal->isPowerOf2())
113 Elts.push_back(ConstantInt::get(Elt->getType(), IVal->logBase2()));
116 return ConstantVector::get(Elts);
119 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
120 bool Changed = SimplifyAssociativeOrCommutative(I);
121 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
123 if (Value *V = SimplifyVectorOp(I))
124 return ReplaceInstUsesWith(I, V);
126 if (Value *V = SimplifyMulInst(Op0, Op1, DL))
127 return ReplaceInstUsesWith(I, V);
129 if (Value *V = SimplifyUsingDistributiveLaws(I))
130 return ReplaceInstUsesWith(I, V);
132 if (match(Op1, m_AllOnes())) // X * -1 == 0 - X
133 return BinaryOperator::CreateNeg(Op0, I.getName());
135 // Also allow combining multiply instructions on vectors.
140 if (match(&I, m_Mul(m_Shl(m_Value(NewOp), m_Constant(C2)),
142 match(C1, m_APInt(IVal)))
143 // ((X << C1)*C2) == (X * (C2 << C1))
144 return BinaryOperator::CreateMul(NewOp, ConstantExpr::getShl(C1, C2));
146 if (match(&I, m_Mul(m_Value(NewOp), m_Constant(C1)))) {
147 Constant *NewCst = nullptr;
148 if (match(C1, m_APInt(IVal)) && IVal->isPowerOf2())
149 // Replace X*(2^C) with X << C, where C is either a scalar or a splat.
150 NewCst = ConstantInt::get(NewOp->getType(), IVal->logBase2());
151 else if (ConstantDataVector *CV = dyn_cast<ConstantDataVector>(C1))
152 // Replace X*(2^C) with X << C, where C is a vector of known
153 // constant powers of 2.
154 NewCst = getLogBase2Vector(CV);
157 BinaryOperator *Shl = BinaryOperator::CreateShl(NewOp, NewCst);
158 if (I.hasNoSignedWrap()) Shl->setHasNoSignedWrap();
159 if (I.hasNoUnsignedWrap()) Shl->setHasNoUnsignedWrap();
165 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
166 // (Y - X) * (-(2**n)) -> (X - Y) * (2**n), for positive nonzero n
167 // (Y + const) * (-(2**n)) -> (-constY) * (2**n), for positive nonzero n
168 // The "* (2**n)" thus becomes a potential shifting opportunity.
170 const APInt & Val = CI->getValue();
171 const APInt &PosVal = Val.abs();
172 if (Val.isNegative() && PosVal.isPowerOf2()) {
173 Value *X = nullptr, *Y = nullptr;
174 if (Op0->hasOneUse()) {
176 Value *Sub = nullptr;
177 if (match(Op0, m_Sub(m_Value(Y), m_Value(X))))
178 Sub = Builder->CreateSub(X, Y, "suba");
179 else if (match(Op0, m_Add(m_Value(Y), m_ConstantInt(C1))))
180 Sub = Builder->CreateSub(Builder->CreateNeg(C1), Y, "subc");
183 BinaryOperator::CreateMul(Sub,
184 ConstantInt::get(Y->getType(), PosVal));
190 // Simplify mul instructions with a constant RHS.
191 if (isa<Constant>(Op1)) {
192 // Try to fold constant mul into select arguments.
193 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
194 if (Instruction *R = FoldOpIntoSelect(I, SI))
197 if (isa<PHINode>(Op0))
198 if (Instruction *NV = FoldOpIntoPhi(I))
201 // Canonicalize (X+C1)*CI -> X*CI+C1*CI.
205 if (match(Op0, m_OneUse(m_Add(m_Value(X), m_Constant(C1))))) {
206 Value *Add = Builder->CreateMul(X, Op1);
207 return BinaryOperator::CreateAdd(Add, Builder->CreateMul(C1, Op1));
212 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
213 if (Value *Op1v = dyn_castNegVal(Op1))
214 return BinaryOperator::CreateMul(Op0v, Op1v);
216 // (X / Y) * Y = X - (X % Y)
217 // (X / Y) * -Y = (X % Y) - X
220 BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0);
222 (BO->getOpcode() != Instruction::UDiv &&
223 BO->getOpcode() != Instruction::SDiv)) {
225 BO = dyn_cast<BinaryOperator>(Op1);
227 Value *Neg = dyn_castNegVal(Op1C);
228 if (BO && BO->hasOneUse() &&
229 (BO->getOperand(1) == Op1C || BO->getOperand(1) == Neg) &&
230 (BO->getOpcode() == Instruction::UDiv ||
231 BO->getOpcode() == Instruction::SDiv)) {
232 Value *Op0BO = BO->getOperand(0), *Op1BO = BO->getOperand(1);
234 // If the division is exact, X % Y is zero, so we end up with X or -X.
235 if (PossiblyExactOperator *SDiv = dyn_cast<PossiblyExactOperator>(BO))
236 if (SDiv->isExact()) {
238 return ReplaceInstUsesWith(I, Op0BO);
239 return BinaryOperator::CreateNeg(Op0BO);
243 if (BO->getOpcode() == Instruction::UDiv)
244 Rem = Builder->CreateURem(Op0BO, Op1BO);
246 Rem = Builder->CreateSRem(Op0BO, Op1BO);
250 return BinaryOperator::CreateSub(Op0BO, Rem);
251 return BinaryOperator::CreateSub(Rem, Op0BO);
255 /// i1 mul -> i1 and.
256 if (I.getType()->getScalarType()->isIntegerTy(1))
257 return BinaryOperator::CreateAnd(Op0, Op1);
259 // X*(1 << Y) --> X << Y
260 // (1 << Y)*X --> X << Y
263 if (match(Op0, m_Shl(m_One(), m_Value(Y))))
264 return BinaryOperator::CreateShl(Op1, Y);
265 if (match(Op1, m_Shl(m_One(), m_Value(Y))))
266 return BinaryOperator::CreateShl(Op0, Y);
269 // If one of the operands of the multiply is a cast from a boolean value, then
270 // we know the bool is either zero or one, so this is a 'masking' multiply.
271 // X * Y (where Y is 0 or 1) -> X & (0-Y)
272 if (!I.getType()->isVectorTy()) {
273 // -2 is "-1 << 1" so it is all bits set except the low one.
274 APInt Negative2(I.getType()->getPrimitiveSizeInBits(), (uint64_t)-2, true);
276 Value *BoolCast = nullptr, *OtherOp = nullptr;
277 if (MaskedValueIsZero(Op0, Negative2))
278 BoolCast = Op0, OtherOp = Op1;
279 else if (MaskedValueIsZero(Op1, Negative2))
280 BoolCast = Op1, OtherOp = Op0;
283 Value *V = Builder->CreateSub(Constant::getNullValue(I.getType()),
285 return BinaryOperator::CreateAnd(V, OtherOp);
289 return Changed ? &I : nullptr;
297 // And check for corresponding fast math flags
300 static void detectLog2OfHalf(Value *&Op, Value *&Y, IntrinsicInst *&Log2) {
302 if (!Op->hasOneUse())
305 IntrinsicInst *II = dyn_cast<IntrinsicInst>(Op);
308 if (II->getIntrinsicID() != Intrinsic::log2 || !II->hasUnsafeAlgebra())
312 Value *OpLog2Of = II->getArgOperand(0);
313 if (!OpLog2Of->hasOneUse())
316 Instruction *I = dyn_cast<Instruction>(OpLog2Of);
319 if (I->getOpcode() != Instruction::FMul || !I->hasUnsafeAlgebra())
322 if (match(I->getOperand(0), m_SpecificFP(0.5)))
323 Y = I->getOperand(1);
324 else if (match(I->getOperand(1), m_SpecificFP(0.5)))
325 Y = I->getOperand(0);
328 static bool isFiniteNonZeroFp(Constant *C) {
329 if (C->getType()->isVectorTy()) {
330 for (unsigned I = 0, E = C->getType()->getVectorNumElements(); I != E;
332 ConstantFP *CFP = dyn_cast<ConstantFP>(C->getAggregateElement(I));
333 if (!CFP || !CFP->getValueAPF().isFiniteNonZero())
339 return isa<ConstantFP>(C) &&
340 cast<ConstantFP>(C)->getValueAPF().isFiniteNonZero();
343 static bool isNormalFp(Constant *C) {
344 if (C->getType()->isVectorTy()) {
345 for (unsigned I = 0, E = C->getType()->getVectorNumElements(); I != E;
347 ConstantFP *CFP = dyn_cast<ConstantFP>(C->getAggregateElement(I));
348 if (!CFP || !CFP->getValueAPF().isNormal())
354 return isa<ConstantFP>(C) && cast<ConstantFP>(C)->getValueAPF().isNormal();
357 /// Helper function of InstCombiner::visitFMul(BinaryOperator(). It returns
358 /// true iff the given value is FMul or FDiv with one and only one operand
359 /// being a normal constant (i.e. not Zero/NaN/Infinity).
360 static bool isFMulOrFDivWithConstant(Value *V) {
361 Instruction *I = dyn_cast<Instruction>(V);
362 if (!I || (I->getOpcode() != Instruction::FMul &&
363 I->getOpcode() != Instruction::FDiv))
366 Constant *C0 = dyn_cast<Constant>(I->getOperand(0));
367 Constant *C1 = dyn_cast<Constant>(I->getOperand(1));
372 return (C0 && isFiniteNonZeroFp(C0)) || (C1 && isFiniteNonZeroFp(C1));
375 /// foldFMulConst() is a helper routine of InstCombiner::visitFMul().
376 /// The input \p FMulOrDiv is a FMul/FDiv with one and only one operand
377 /// being a constant (i.e. isFMulOrFDivWithConstant(FMulOrDiv) == true).
378 /// This function is to simplify "FMulOrDiv * C" and returns the
379 /// resulting expression. Note that this function could return NULL in
380 /// case the constants cannot be folded into a normal floating-point.
382 Value *InstCombiner::foldFMulConst(Instruction *FMulOrDiv, Constant *C,
383 Instruction *InsertBefore) {
384 assert(isFMulOrFDivWithConstant(FMulOrDiv) && "V is invalid");
386 Value *Opnd0 = FMulOrDiv->getOperand(0);
387 Value *Opnd1 = FMulOrDiv->getOperand(1);
389 Constant *C0 = dyn_cast<Constant>(Opnd0);
390 Constant *C1 = dyn_cast<Constant>(Opnd1);
392 BinaryOperator *R = nullptr;
394 // (X * C0) * C => X * (C0*C)
395 if (FMulOrDiv->getOpcode() == Instruction::FMul) {
396 Constant *F = ConstantExpr::getFMul(C1 ? C1 : C0, C);
398 R = BinaryOperator::CreateFMul(C1 ? Opnd0 : Opnd1, F);
401 // (C0 / X) * C => (C0 * C) / X
402 if (FMulOrDiv->hasOneUse()) {
403 // It would otherwise introduce another div.
404 Constant *F = ConstantExpr::getFMul(C0, C);
406 R = BinaryOperator::CreateFDiv(F, Opnd1);
409 // (X / C1) * C => X * (C/C1) if C/C1 is not a denormal
410 Constant *F = ConstantExpr::getFDiv(C, C1);
412 R = BinaryOperator::CreateFMul(Opnd0, F);
414 // (X / C1) * C => X / (C1/C)
415 Constant *F = ConstantExpr::getFDiv(C1, C);
417 R = BinaryOperator::CreateFDiv(Opnd0, F);
423 R->setHasUnsafeAlgebra(true);
424 InsertNewInstWith(R, *InsertBefore);
430 Instruction *InstCombiner::visitFMul(BinaryOperator &I) {
431 bool Changed = SimplifyAssociativeOrCommutative(I);
432 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
434 if (Value *V = SimplifyVectorOp(I))
435 return ReplaceInstUsesWith(I, V);
437 if (isa<Constant>(Op0))
440 if (Value *V = SimplifyFMulInst(Op0, Op1, I.getFastMathFlags(), DL))
441 return ReplaceInstUsesWith(I, V);
443 bool AllowReassociate = I.hasUnsafeAlgebra();
445 // Simplify mul instructions with a constant RHS.
446 if (isa<Constant>(Op1)) {
447 // Try to fold constant mul into select arguments.
448 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
449 if (Instruction *R = FoldOpIntoSelect(I, SI))
452 if (isa<PHINode>(Op0))
453 if (Instruction *NV = FoldOpIntoPhi(I))
456 // (fmul X, -1.0) --> (fsub -0.0, X)
457 if (match(Op1, m_SpecificFP(-1.0))) {
458 Constant *NegZero = ConstantFP::getNegativeZero(Op1->getType());
459 Instruction *RI = BinaryOperator::CreateFSub(NegZero, Op0);
460 RI->copyFastMathFlags(&I);
464 Constant *C = cast<Constant>(Op1);
465 if (AllowReassociate && isFiniteNonZeroFp(C)) {
466 // Let MDC denote an expression in one of these forms:
467 // X * C, C/X, X/C, where C is a constant.
469 // Try to simplify "MDC * Constant"
470 if (isFMulOrFDivWithConstant(Op0))
471 if (Value *V = foldFMulConst(cast<Instruction>(Op0), C, &I))
472 return ReplaceInstUsesWith(I, V);
474 // (MDC +/- C1) * C => (MDC * C) +/- (C1 * C)
475 Instruction *FAddSub = dyn_cast<Instruction>(Op0);
477 (FAddSub->getOpcode() == Instruction::FAdd ||
478 FAddSub->getOpcode() == Instruction::FSub)) {
479 Value *Opnd0 = FAddSub->getOperand(0);
480 Value *Opnd1 = FAddSub->getOperand(1);
481 Constant *C0 = dyn_cast<Constant>(Opnd0);
482 Constant *C1 = dyn_cast<Constant>(Opnd1);
486 std::swap(Opnd0, Opnd1);
490 if (C1 && isFiniteNonZeroFp(C1) && isFMulOrFDivWithConstant(Opnd0)) {
491 Value *M1 = ConstantExpr::getFMul(C1, C);
492 Value *M0 = isNormalFp(cast<Constant>(M1)) ?
493 foldFMulConst(cast<Instruction>(Opnd0), C, &I) :
496 if (Swap && FAddSub->getOpcode() == Instruction::FSub)
499 Instruction *RI = (FAddSub->getOpcode() == Instruction::FAdd)
500 ? BinaryOperator::CreateFAdd(M0, M1)
501 : BinaryOperator::CreateFSub(M0, M1);
502 RI->copyFastMathFlags(&I);
511 // Under unsafe algebra do:
512 // X * log2(0.5*Y) = X*log2(Y) - X
513 if (I.hasUnsafeAlgebra()) {
514 Value *OpX = nullptr;
515 Value *OpY = nullptr;
517 detectLog2OfHalf(Op0, OpY, Log2);
521 detectLog2OfHalf(Op1, OpY, Log2);
526 // if pattern detected emit alternate sequence
528 BuilderTy::FastMathFlagGuard Guard(*Builder);
529 Builder->SetFastMathFlags(Log2->getFastMathFlags());
530 Log2->setArgOperand(0, OpY);
531 Value *FMulVal = Builder->CreateFMul(OpX, Log2);
532 Value *FSub = Builder->CreateFSub(FMulVal, OpX);
534 return ReplaceInstUsesWith(I, FSub);
538 // Handle symmetric situation in a 2-iteration loop
541 for (int i = 0; i < 2; i++) {
542 bool IgnoreZeroSign = I.hasNoSignedZeros();
543 if (BinaryOperator::isFNeg(Opnd0, IgnoreZeroSign)) {
544 BuilderTy::FastMathFlagGuard Guard(*Builder);
545 Builder->SetFastMathFlags(I.getFastMathFlags());
547 Value *N0 = dyn_castFNegVal(Opnd0, IgnoreZeroSign);
548 Value *N1 = dyn_castFNegVal(Opnd1, IgnoreZeroSign);
552 Value *FMul = Builder->CreateFMul(N0, N1);
554 return ReplaceInstUsesWith(I, FMul);
557 if (Opnd0->hasOneUse()) {
558 // -X * Y => -(X*Y) (Promote negation as high as possible)
559 Value *T = Builder->CreateFMul(N0, Opnd1);
560 Value *Neg = Builder->CreateFNeg(T);
562 return ReplaceInstUsesWith(I, Neg);
566 // (X*Y) * X => (X*X) * Y where Y != X
567 // The purpose is two-fold:
568 // 1) to form a power expression (of X).
569 // 2) potentially shorten the critical path: After transformation, the
570 // latency of the instruction Y is amortized by the expression of X*X,
571 // and therefore Y is in a "less critical" position compared to what it
572 // was before the transformation.
574 if (AllowReassociate) {
575 Value *Opnd0_0, *Opnd0_1;
576 if (Opnd0->hasOneUse() &&
577 match(Opnd0, m_FMul(m_Value(Opnd0_0), m_Value(Opnd0_1)))) {
579 if (Opnd0_0 == Opnd1 && Opnd0_1 != Opnd1)
581 else if (Opnd0_1 == Opnd1 && Opnd0_0 != Opnd1)
585 BuilderTy::FastMathFlagGuard Guard(*Builder);
586 Builder->SetFastMathFlags(I.getFastMathFlags());
587 Value *T = Builder->CreateFMul(Opnd1, Opnd1);
589 Value *R = Builder->CreateFMul(T, Y);
591 return ReplaceInstUsesWith(I, R);
596 // B * (uitofp i1 C) -> select C, B, 0
597 if (I.hasNoNaNs() && I.hasNoInfs() && I.hasNoSignedZeros()) {
598 Value *LHS = Op0, *RHS = Op1;
600 if (!match(RHS, m_UIToFP(m_Value(C))))
603 if (match(RHS, m_UIToFP(m_Value(C))) &&
604 C->getType()->getScalarType()->isIntegerTy(1)) {
606 Value *Zero = ConstantFP::getNegativeZero(B->getType());
607 return SelectInst::Create(C, B, Zero);
611 // A * (1 - uitofp i1 C) -> select C, 0, A
612 if (I.hasNoNaNs() && I.hasNoInfs() && I.hasNoSignedZeros()) {
613 Value *LHS = Op0, *RHS = Op1;
615 if (!match(RHS, m_FSub(m_FPOne(), m_UIToFP(m_Value(C)))))
618 if (match(RHS, m_FSub(m_FPOne(), m_UIToFP(m_Value(C)))) &&
619 C->getType()->getScalarType()->isIntegerTy(1)) {
621 Value *Zero = ConstantFP::getNegativeZero(A->getType());
622 return SelectInst::Create(C, Zero, A);
626 if (!isa<Constant>(Op1))
627 std::swap(Opnd0, Opnd1);
632 return Changed ? &I : nullptr;
635 /// SimplifyDivRemOfSelect - Try to fold a divide or remainder of a select
637 bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) {
638 SelectInst *SI = cast<SelectInst>(I.getOperand(1));
640 // div/rem X, (Cond ? 0 : Y) -> div/rem X, Y
641 int NonNullOperand = -1;
642 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
643 if (ST->isNullValue())
645 // div/rem X, (Cond ? Y : 0) -> div/rem X, Y
646 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
647 if (ST->isNullValue())
650 if (NonNullOperand == -1)
653 Value *SelectCond = SI->getOperand(0);
655 // Change the div/rem to use 'Y' instead of the select.
656 I.setOperand(1, SI->getOperand(NonNullOperand));
658 // Okay, we know we replace the operand of the div/rem with 'Y' with no
659 // problem. However, the select, or the condition of the select may have
660 // multiple uses. Based on our knowledge that the operand must be non-zero,
661 // propagate the known value for the select into other uses of it, and
662 // propagate a known value of the condition into its other users.
664 // If the select and condition only have a single use, don't bother with this,
666 if (SI->use_empty() && SelectCond->hasOneUse())
669 // Scan the current block backward, looking for other uses of SI.
670 BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin();
672 while (BBI != BBFront) {
674 // If we found a call to a function, we can't assume it will return, so
675 // information from below it cannot be propagated above it.
676 if (isa<CallInst>(BBI) && !isa<IntrinsicInst>(BBI))
679 // Replace uses of the select or its condition with the known values.
680 for (Instruction::op_iterator I = BBI->op_begin(), E = BBI->op_end();
683 *I = SI->getOperand(NonNullOperand);
685 } else if (*I == SelectCond) {
686 *I = Builder->getInt1(NonNullOperand == 1);
691 // If we past the instruction, quit looking for it.
694 if (&*BBI == SelectCond)
695 SelectCond = nullptr;
697 // If we ran out of things to eliminate, break out of the loop.
698 if (!SelectCond && !SI)
706 /// This function implements the transforms common to both integer division
707 /// instructions (udiv and sdiv). It is called by the visitors to those integer
708 /// division instructions.
709 /// @brief Common integer divide transforms
710 Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
711 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
713 // The RHS is known non-zero.
714 if (Value *V = simplifyValueKnownNonZero(I.getOperand(1), *this)) {
719 // Handle cases involving: [su]div X, (select Cond, Y, Z)
720 // This does not apply for fdiv.
721 if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
724 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
725 // (X / C1) / C2 -> X / (C1*C2)
726 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
727 if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
728 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
729 if (MultiplyOverflows(RHS, LHSRHS,
730 I.getOpcode() == Instruction::SDiv))
731 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
732 return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0),
733 ConstantExpr::getMul(RHS, LHSRHS));
736 if (!RHS->isZero()) { // avoid X udiv 0
737 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
738 if (Instruction *R = FoldOpIntoSelect(I, SI))
740 if (isa<PHINode>(Op0))
741 if (Instruction *NV = FoldOpIntoPhi(I))
746 if (ConstantInt *One = dyn_cast<ConstantInt>(Op0)) {
747 if (One->isOne() && !I.getType()->isIntegerTy(1)) {
748 bool isSigned = I.getOpcode() == Instruction::SDiv;
750 // If Op1 is 0 then it's undefined behaviour, if Op1 is 1 then the
751 // result is one, if Op1 is -1 then the result is minus one, otherwise
753 Value *Inc = Builder->CreateAdd(Op1, One);
754 Value *Cmp = Builder->CreateICmpULT(
755 Inc, ConstantInt::get(I.getType(), 3));
756 return SelectInst::Create(Cmp, Op1, ConstantInt::get(I.getType(), 0));
758 // If Op1 is 0 then it's undefined behaviour. If Op1 is 1 then the
759 // result is one, otherwise it's zero.
760 return new ZExtInst(Builder->CreateICmpEQ(Op1, One), I.getType());
765 // See if we can fold away this div instruction.
766 if (SimplifyDemandedInstructionBits(I))
769 // (X - (X rem Y)) / Y -> X / Y; usually originates as ((X / Y) * Y) / Y
770 Value *X = nullptr, *Z = nullptr;
771 if (match(Op0, m_Sub(m_Value(X), m_Value(Z)))) { // (X - Z) / Y; Y = Op1
772 bool isSigned = I.getOpcode() == Instruction::SDiv;
773 if ((isSigned && match(Z, m_SRem(m_Specific(X), m_Specific(Op1)))) ||
774 (!isSigned && match(Z, m_URem(m_Specific(X), m_Specific(Op1)))))
775 return BinaryOperator::Create(I.getOpcode(), X, Op1);
781 /// dyn_castZExtVal - Checks if V is a zext or constant that can
782 /// be truncated to Ty without losing bits.
783 static Value *dyn_castZExtVal(Value *V, Type *Ty) {
784 if (ZExtInst *Z = dyn_cast<ZExtInst>(V)) {
785 if (Z->getSrcTy() == Ty)
786 return Z->getOperand(0);
787 } else if (ConstantInt *C = dyn_cast<ConstantInt>(V)) {
788 if (C->getValue().getActiveBits() <= cast<IntegerType>(Ty)->getBitWidth())
789 return ConstantExpr::getTrunc(C, Ty);
795 const unsigned MaxDepth = 6;
796 typedef Instruction *(*FoldUDivOperandCb)(Value *Op0, Value *Op1,
797 const BinaryOperator &I,
800 /// \brief Used to maintain state for visitUDivOperand().
801 struct UDivFoldAction {
802 FoldUDivOperandCb FoldAction; ///< Informs visitUDiv() how to fold this
803 ///< operand. This can be zero if this action
804 ///< joins two actions together.
806 Value *OperandToFold; ///< Which operand to fold.
808 Instruction *FoldResult; ///< The instruction returned when FoldAction is
811 size_t SelectLHSIdx; ///< Stores the LHS action index if this action
812 ///< joins two actions together.
815 UDivFoldAction(FoldUDivOperandCb FA, Value *InputOperand)
816 : FoldAction(FA), OperandToFold(InputOperand), FoldResult(nullptr) {}
817 UDivFoldAction(FoldUDivOperandCb FA, Value *InputOperand, size_t SLHS)
818 : FoldAction(FA), OperandToFold(InputOperand), SelectLHSIdx(SLHS) {}
822 // X udiv 2^C -> X >> C
823 static Instruction *foldUDivPow2Cst(Value *Op0, Value *Op1,
824 const BinaryOperator &I, InstCombiner &IC) {
825 const APInt &C = cast<Constant>(Op1)->getUniqueInteger();
826 BinaryOperator *LShr = BinaryOperator::CreateLShr(
827 Op0, ConstantInt::get(Op0->getType(), C.logBase2()));
828 if (I.isExact()) LShr->setIsExact();
832 // X udiv C, where C >= signbit
833 static Instruction *foldUDivNegCst(Value *Op0, Value *Op1,
834 const BinaryOperator &I, InstCombiner &IC) {
835 Value *ICI = IC.Builder->CreateICmpULT(Op0, cast<ConstantInt>(Op1));
837 return SelectInst::Create(ICI, Constant::getNullValue(I.getType()),
838 ConstantInt::get(I.getType(), 1));
841 // X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
842 static Instruction *foldUDivShl(Value *Op0, Value *Op1, const BinaryOperator &I,
844 Instruction *ShiftLeft = cast<Instruction>(Op1);
845 if (isa<ZExtInst>(ShiftLeft))
846 ShiftLeft = cast<Instruction>(ShiftLeft->getOperand(0));
849 cast<Constant>(ShiftLeft->getOperand(0))->getUniqueInteger();
850 Value *N = ShiftLeft->getOperand(1);
852 N = IC.Builder->CreateAdd(N, ConstantInt::get(N->getType(), CI.logBase2()));
853 if (ZExtInst *Z = dyn_cast<ZExtInst>(Op1))
854 N = IC.Builder->CreateZExt(N, Z->getDestTy());
855 BinaryOperator *LShr = BinaryOperator::CreateLShr(Op0, N);
856 if (I.isExact()) LShr->setIsExact();
860 // \brief Recursively visits the possible right hand operands of a udiv
861 // instruction, seeing through select instructions, to determine if we can
862 // replace the udiv with something simpler. If we find that an operand is not
863 // able to simplify the udiv, we abort the entire transformation.
864 static size_t visitUDivOperand(Value *Op0, Value *Op1, const BinaryOperator &I,
865 SmallVectorImpl<UDivFoldAction> &Actions,
866 unsigned Depth = 0) {
867 // Check to see if this is an unsigned division with an exact power of 2,
868 // if so, convert to a right shift.
869 if (match(Op1, m_Power2())) {
870 Actions.push_back(UDivFoldAction(foldUDivPow2Cst, Op1));
871 return Actions.size();
874 if (ConstantInt *C = dyn_cast<ConstantInt>(Op1))
875 // X udiv C, where C >= signbit
876 if (C->getValue().isNegative()) {
877 Actions.push_back(UDivFoldAction(foldUDivNegCst, C));
878 return Actions.size();
881 // X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
882 if (match(Op1, m_Shl(m_Power2(), m_Value())) ||
883 match(Op1, m_ZExt(m_Shl(m_Power2(), m_Value())))) {
884 Actions.push_back(UDivFoldAction(foldUDivShl, Op1));
885 return Actions.size();
888 // The remaining tests are all recursive, so bail out if we hit the limit.
889 if (Depth++ == MaxDepth)
892 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
893 if (size_t LHSIdx = visitUDivOperand(Op0, SI->getOperand(1), I, Actions))
894 if (visitUDivOperand(Op0, SI->getOperand(2), I, Actions)) {
895 Actions.push_back(UDivFoldAction((FoldUDivOperandCb)nullptr, Op1,
897 return Actions.size();
903 Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
904 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
906 if (Value *V = SimplifyVectorOp(I))
907 return ReplaceInstUsesWith(I, V);
909 if (Value *V = SimplifyUDivInst(Op0, Op1, DL))
910 return ReplaceInstUsesWith(I, V);
912 // Handle the integer div common cases
913 if (Instruction *Common = commonIDivTransforms(I))
916 // (x lshr C1) udiv C2 --> x udiv (C2 << C1)
917 if (Constant *C2 = dyn_cast<Constant>(Op1)) {
920 if (match(Op0, m_LShr(m_Value(X), m_Constant(C1))))
921 return BinaryOperator::CreateUDiv(X, ConstantExpr::getShl(C2, C1));
924 // (zext A) udiv (zext B) --> zext (A udiv B)
925 if (ZExtInst *ZOp0 = dyn_cast<ZExtInst>(Op0))
926 if (Value *ZOp1 = dyn_castZExtVal(Op1, ZOp0->getSrcTy()))
927 return new ZExtInst(Builder->CreateUDiv(ZOp0->getOperand(0), ZOp1, "div",
931 // (LHS udiv (select (select (...)))) -> (LHS >> (select (select (...))))
932 SmallVector<UDivFoldAction, 6> UDivActions;
933 if (visitUDivOperand(Op0, Op1, I, UDivActions))
934 for (unsigned i = 0, e = UDivActions.size(); i != e; ++i) {
935 FoldUDivOperandCb Action = UDivActions[i].FoldAction;
936 Value *ActionOp1 = UDivActions[i].OperandToFold;
939 Inst = Action(Op0, ActionOp1, I, *this);
941 // This action joins two actions together. The RHS of this action is
942 // simply the last action we processed, we saved the LHS action index in
943 // the joining action.
944 size_t SelectRHSIdx = i - 1;
945 Value *SelectRHS = UDivActions[SelectRHSIdx].FoldResult;
946 size_t SelectLHSIdx = UDivActions[i].SelectLHSIdx;
947 Value *SelectLHS = UDivActions[SelectLHSIdx].FoldResult;
948 Inst = SelectInst::Create(cast<SelectInst>(ActionOp1)->getCondition(),
949 SelectLHS, SelectRHS);
952 // If this is the last action to process, return it to the InstCombiner.
953 // Otherwise, we insert it before the UDiv and record it so that we may
954 // use it as part of a joining action (i.e., a SelectInst).
956 Inst->insertBefore(&I);
957 UDivActions[i].FoldResult = Inst;
965 Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
966 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
968 if (Value *V = SimplifyVectorOp(I))
969 return ReplaceInstUsesWith(I, V);
971 if (Value *V = SimplifySDivInst(Op0, Op1, DL))
972 return ReplaceInstUsesWith(I, V);
974 // Handle the integer div common cases
975 if (Instruction *Common = commonIDivTransforms(I))
979 if (match(Op1, m_AllOnes()))
980 return BinaryOperator::CreateNeg(Op0);
982 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
983 // sdiv X, C --> ashr exact X, log2(C)
984 if (I.isExact() && RHS->getValue().isNonNegative() &&
985 RHS->getValue().isPowerOf2()) {
986 Value *ShAmt = llvm::ConstantInt::get(RHS->getType(),
987 RHS->getValue().exactLogBase2());
988 return BinaryOperator::CreateExactAShr(Op0, ShAmt, I.getName());
992 if (Constant *RHS = dyn_cast<Constant>(Op1)) {
993 // -X/C --> X/-C provided the negation doesn't overflow.
994 if (SubOperator *Sub = dyn_cast<SubOperator>(Op0))
995 if (match(Sub->getOperand(0), m_Zero()) && Sub->hasNoSignedWrap())
996 return BinaryOperator::CreateSDiv(Sub->getOperand(1),
997 ConstantExpr::getNeg(RHS));
1000 // If the sign bits of both operands are zero (i.e. we can prove they are
1001 // unsigned inputs), turn this into a udiv.
1002 if (I.getType()->isIntegerTy()) {
1003 APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
1004 if (MaskedValueIsZero(Op0, Mask)) {
1005 if (MaskedValueIsZero(Op1, Mask)) {
1006 // X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
1007 return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
1010 if (match(Op1, m_Shl(m_Power2(), m_Value()))) {
1011 // X sdiv (1 << Y) -> X udiv (1 << Y) ( -> X u>> Y)
1012 // Safe because the only negative value (1 << Y) can take on is
1013 // INT_MIN, and X sdiv INT_MIN == X udiv INT_MIN == 0 if X doesn't have
1014 // the sign bit set.
1015 return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
1023 /// CvtFDivConstToReciprocal tries to convert X/C into X*1/C if C not a special
1025 /// 1) 1/C is exact, or
1026 /// 2) reciprocal is allowed.
1027 /// If the conversion was successful, the simplified expression "X * 1/C" is
1028 /// returned; otherwise, NULL is returned.
1030 static Instruction *CvtFDivConstToReciprocal(Value *Dividend,
1032 bool AllowReciprocal) {
1033 if (!isa<ConstantFP>(Divisor)) // TODO: handle vectors.
1036 const APFloat &FpVal = cast<ConstantFP>(Divisor)->getValueAPF();
1037 APFloat Reciprocal(FpVal.getSemantics());
1038 bool Cvt = FpVal.getExactInverse(&Reciprocal);
1040 if (!Cvt && AllowReciprocal && FpVal.isFiniteNonZero()) {
1041 Reciprocal = APFloat(FpVal.getSemantics(), 1.0f);
1042 (void)Reciprocal.divide(FpVal, APFloat::rmNearestTiesToEven);
1043 Cvt = !Reciprocal.isDenormal();
1050 R = ConstantFP::get(Dividend->getType()->getContext(), Reciprocal);
1051 return BinaryOperator::CreateFMul(Dividend, R);
1054 Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
1055 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1057 if (Value *V = SimplifyVectorOp(I))
1058 return ReplaceInstUsesWith(I, V);
1060 if (Value *V = SimplifyFDivInst(Op0, Op1, DL))
1061 return ReplaceInstUsesWith(I, V);
1063 if (isa<Constant>(Op0))
1064 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1065 if (Instruction *R = FoldOpIntoSelect(I, SI))
1068 bool AllowReassociate = I.hasUnsafeAlgebra();
1069 bool AllowReciprocal = I.hasAllowReciprocal();
1071 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
1072 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1073 if (Instruction *R = FoldOpIntoSelect(I, SI))
1076 if (AllowReassociate) {
1077 Constant *C1 = nullptr;
1078 Constant *C2 = Op1C;
1080 Instruction *Res = nullptr;
1082 if (match(Op0, m_FMul(m_Value(X), m_Constant(C1)))) {
1083 // (X*C1)/C2 => X * (C1/C2)
1085 Constant *C = ConstantExpr::getFDiv(C1, C2);
1087 Res = BinaryOperator::CreateFMul(X, C);
1088 } else if (match(Op0, m_FDiv(m_Value(X), m_Constant(C1)))) {
1089 // (X/C1)/C2 => X /(C2*C1) [=> X * 1/(C2*C1) if reciprocal is allowed]
1091 Constant *C = ConstantExpr::getFMul(C1, C2);
1092 if (isNormalFp(C)) {
1093 Res = CvtFDivConstToReciprocal(X, C, AllowReciprocal);
1095 Res = BinaryOperator::CreateFDiv(X, C);
1100 Res->setFastMathFlags(I.getFastMathFlags());
1106 if (Instruction *T = CvtFDivConstToReciprocal(Op0, Op1C, AllowReciprocal)) {
1107 T->copyFastMathFlags(&I);
1114 if (AllowReassociate && isa<Constant>(Op0)) {
1115 Constant *C1 = cast<Constant>(Op0), *C2;
1116 Constant *Fold = nullptr;
1118 bool CreateDiv = true;
1120 // C1 / (X*C2) => (C1/C2) / X
1121 if (match(Op1, m_FMul(m_Value(X), m_Constant(C2))))
1122 Fold = ConstantExpr::getFDiv(C1, C2);
1123 else if (match(Op1, m_FDiv(m_Value(X), m_Constant(C2)))) {
1124 // C1 / (X/C2) => (C1*C2) / X
1125 Fold = ConstantExpr::getFMul(C1, C2);
1126 } else if (match(Op1, m_FDiv(m_Constant(C2), m_Value(X)))) {
1127 // C1 / (C2/X) => (C1/C2) * X
1128 Fold = ConstantExpr::getFDiv(C1, C2);
1132 if (Fold && isNormalFp(Fold)) {
1133 Instruction *R = CreateDiv ? BinaryOperator::CreateFDiv(Fold, X)
1134 : BinaryOperator::CreateFMul(X, Fold);
1135 R->setFastMathFlags(I.getFastMathFlags());
1141 if (AllowReassociate) {
1143 Value *NewInst = nullptr;
1144 Instruction *SimpR = nullptr;
1146 if (Op0->hasOneUse() && match(Op0, m_FDiv(m_Value(X), m_Value(Y)))) {
1147 // (X/Y) / Z => X / (Y*Z)
1149 if (!isa<Constant>(Y) || !isa<Constant>(Op1)) {
1150 NewInst = Builder->CreateFMul(Y, Op1);
1151 if (Instruction *RI = dyn_cast<Instruction>(NewInst)) {
1152 FastMathFlags Flags = I.getFastMathFlags();
1153 Flags &= cast<Instruction>(Op0)->getFastMathFlags();
1154 RI->setFastMathFlags(Flags);
1156 SimpR = BinaryOperator::CreateFDiv(X, NewInst);
1158 } else if (Op1->hasOneUse() && match(Op1, m_FDiv(m_Value(X), m_Value(Y)))) {
1159 // Z / (X/Y) => Z*Y / X
1161 if (!isa<Constant>(Y) || !isa<Constant>(Op0)) {
1162 NewInst = Builder->CreateFMul(Op0, Y);
1163 if (Instruction *RI = dyn_cast<Instruction>(NewInst)) {
1164 FastMathFlags Flags = I.getFastMathFlags();
1165 Flags &= cast<Instruction>(Op1)->getFastMathFlags();
1166 RI->setFastMathFlags(Flags);
1168 SimpR = BinaryOperator::CreateFDiv(NewInst, X);
1173 if (Instruction *T = dyn_cast<Instruction>(NewInst))
1174 T->setDebugLoc(I.getDebugLoc());
1175 SimpR->setFastMathFlags(I.getFastMathFlags());
1183 /// This function implements the transforms common to both integer remainder
1184 /// instructions (urem and srem). It is called by the visitors to those integer
1185 /// remainder instructions.
1186 /// @brief Common integer remainder transforms
1187 Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
1188 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1190 // The RHS is known non-zero.
1191 if (Value *V = simplifyValueKnownNonZero(I.getOperand(1), *this)) {
1196 // Handle cases involving: rem X, (select Cond, Y, Z)
1197 if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
1200 if (isa<Constant>(Op1)) {
1201 if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
1202 if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
1203 if (Instruction *R = FoldOpIntoSelect(I, SI))
1205 } else if (isa<PHINode>(Op0I)) {
1206 if (Instruction *NV = FoldOpIntoPhi(I))
1210 // See if we can fold away this rem instruction.
1211 if (SimplifyDemandedInstructionBits(I))
1219 Instruction *InstCombiner::visitURem(BinaryOperator &I) {
1220 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1222 if (Value *V = SimplifyVectorOp(I))
1223 return ReplaceInstUsesWith(I, V);
1225 if (Value *V = SimplifyURemInst(Op0, Op1, DL))
1226 return ReplaceInstUsesWith(I, V);
1228 if (Instruction *common = commonIRemTransforms(I))
1231 // (zext A) urem (zext B) --> zext (A urem B)
1232 if (ZExtInst *ZOp0 = dyn_cast<ZExtInst>(Op0))
1233 if (Value *ZOp1 = dyn_castZExtVal(Op1, ZOp0->getSrcTy()))
1234 return new ZExtInst(Builder->CreateURem(ZOp0->getOperand(0), ZOp1),
1237 // X urem Y -> X and Y-1, where Y is a power of 2,
1238 if (isKnownToBeAPowerOfTwo(Op1, /*OrZero*/true)) {
1239 Constant *N1 = Constant::getAllOnesValue(I.getType());
1240 Value *Add = Builder->CreateAdd(Op1, N1);
1241 return BinaryOperator::CreateAnd(Op0, Add);
1244 // 1 urem X -> zext(X != 1)
1245 if (match(Op0, m_One())) {
1246 Value *Cmp = Builder->CreateICmpNE(Op1, Op0);
1247 Value *Ext = Builder->CreateZExt(Cmp, I.getType());
1248 return ReplaceInstUsesWith(I, Ext);
1254 Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
1255 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1257 if (Value *V = SimplifyVectorOp(I))
1258 return ReplaceInstUsesWith(I, V);
1260 if (Value *V = SimplifySRemInst(Op0, Op1, DL))
1261 return ReplaceInstUsesWith(I, V);
1263 // Handle the integer rem common cases
1264 if (Instruction *Common = commonIRemTransforms(I))
1267 if (Value *RHSNeg = dyn_castNegVal(Op1))
1268 if (!isa<Constant>(RHSNeg) ||
1269 (isa<ConstantInt>(RHSNeg) &&
1270 cast<ConstantInt>(RHSNeg)->getValue().isStrictlyPositive())) {
1272 Worklist.AddValue(I.getOperand(1));
1273 I.setOperand(1, RHSNeg);
1277 // If the sign bits of both operands are zero (i.e. we can prove they are
1278 // unsigned inputs), turn this into a urem.
1279 if (I.getType()->isIntegerTy()) {
1280 APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
1281 if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
1282 // X srem Y -> X urem Y, iff X and Y don't have sign bit set
1283 return BinaryOperator::CreateURem(Op0, Op1, I.getName());
1287 // If it's a constant vector, flip any negative values positive.
1288 if (isa<ConstantVector>(Op1) || isa<ConstantDataVector>(Op1)) {
1289 Constant *C = cast<Constant>(Op1);
1290 unsigned VWidth = C->getType()->getVectorNumElements();
1292 bool hasNegative = false;
1293 bool hasMissing = false;
1294 for (unsigned i = 0; i != VWidth; ++i) {
1295 Constant *Elt = C->getAggregateElement(i);
1301 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Elt))
1302 if (RHS->isNegative())
1306 if (hasNegative && !hasMissing) {
1307 SmallVector<Constant *, 16> Elts(VWidth);
1308 for (unsigned i = 0; i != VWidth; ++i) {
1309 Elts[i] = C->getAggregateElement(i); // Handle undef, etc.
1310 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Elts[i])) {
1311 if (RHS->isNegative())
1312 Elts[i] = cast<ConstantInt>(ConstantExpr::getNeg(RHS));
1316 Constant *NewRHSV = ConstantVector::get(Elts);
1317 if (NewRHSV != C) { // Don't loop on -MININT
1318 Worklist.AddValue(I.getOperand(1));
1319 I.setOperand(1, NewRHSV);
1328 Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
1329 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1331 if (Value *V = SimplifyVectorOp(I))
1332 return ReplaceInstUsesWith(I, V);
1334 if (Value *V = SimplifyFRemInst(Op0, Op1, DL))
1335 return ReplaceInstUsesWith(I, V);
1337 // Handle cases involving: rem X, (select Cond, Y, Z)
1338 if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))