//===- InstCombineMulDivRem.cpp -------------------------------------------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file implements the visit functions for mul, fmul, sdiv, udiv, fdiv, // srem, urem, frem. // //===----------------------------------------------------------------------===// #include "InstCombine.h" #include "llvm/IntrinsicInst.h" #include "llvm/Support/PatternMatch.h" using namespace llvm; using namespace PatternMatch; /// SubOne - Subtract one from a ConstantInt. static Constant *SubOne(ConstantInt *C) { return ConstantInt::get(C->getContext(), C->getValue()-1); } /// MultiplyOverflows - True if the multiply can not be expressed in an int /// this size. static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) { uint32_t W = C1->getBitWidth(); APInt LHSExt = C1->getValue(), RHSExt = C2->getValue(); if (sign) { LHSExt.sext(W * 2); RHSExt.sext(W * 2); } else { LHSExt.zext(W * 2); RHSExt.zext(W * 2); } APInt MulExt = LHSExt * RHSExt; if (!sign) return MulExt.ugt(APInt::getLowBitsSet(W * 2, W)); APInt Min = APInt::getSignedMinValue(W).sext(W * 2); APInt Max = APInt::getSignedMaxValue(W).sext(W * 2); return MulExt.slt(Min) || MulExt.sgt(Max); } Instruction *InstCombiner::visitMul(BinaryOperator &I) { bool Changed = SimplifyCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); if (isa(Op1)) // undef * X -> 0 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); // Simplify mul instructions with a constant RHS. if (Constant *Op1C = dyn_cast(Op1)) { if (ConstantInt *CI = dyn_cast(Op1C)) { // ((X << C1)*C2) == (X * (C2 << C1)) if (BinaryOperator *SI = dyn_cast(Op0)) if (SI->getOpcode() == Instruction::Shl) if (Constant *ShOp = dyn_cast(SI->getOperand(1))) return BinaryOperator::CreateMul(SI->getOperand(0), ConstantExpr::getShl(CI, ShOp)); if (CI->isZero()) return ReplaceInstUsesWith(I, Op1C); // X * 0 == 0 if (CI->equalsInt(1)) // X * 1 == X return ReplaceInstUsesWith(I, Op0); if (CI->isAllOnesValue()) // X * -1 == 0 - X return BinaryOperator::CreateNeg(Op0, I.getName()); const APInt& Val = cast(CI)->getValue(); if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C return BinaryOperator::CreateShl(Op0, ConstantInt::get(Op0->getType(), Val.logBase2())); } } else if (Op1C->getType()->isVectorTy()) { if (Op1C->isNullValue()) return ReplaceInstUsesWith(I, Op1C); if (ConstantVector *Op1V = dyn_cast(Op1C)) { if (Op1V->isAllOnesValue()) // X * -1 == 0 - X return BinaryOperator::CreateNeg(Op0, I.getName()); // As above, vector X*splat(1.0) -> X in all defined cases. if (Constant *Splat = Op1V->getSplatValue()) { if (ConstantInt *CI = dyn_cast(Splat)) if (CI->equalsInt(1)) return ReplaceInstUsesWith(I, Op0); } } } if (BinaryOperator *Op0I = dyn_cast(Op0)) if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() && isa(Op0I->getOperand(1)) && isa(Op1C)) { // Canonicalize (X+C1)*C2 -> X*C2+C1*C2. Value *Add = Builder->CreateMul(Op0I->getOperand(0), Op1C, "tmp"); Value *C1C2 = Builder->CreateMul(Op1C, Op0I->getOperand(1)); return BinaryOperator::CreateAdd(Add, C1C2); } // Try to fold constant mul into select arguments. if (SelectInst *SI = dyn_cast(Op0)) if (Instruction *R = FoldOpIntoSelect(I, SI)) return R; if (isa(Op0)) if (Instruction *NV = FoldOpIntoPhi(I)) return NV; } if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y if (Value *Op1v = dyn_castNegVal(Op1)) return BinaryOperator::CreateMul(Op0v, Op1v); // (X / Y) * Y = X - (X % Y) // (X / Y) * -Y = (X % Y) - X { Value *Op1C = Op1; BinaryOperator *BO = dyn_cast(Op0); if (!BO || (BO->getOpcode() != Instruction::UDiv && BO->getOpcode() != Instruction::SDiv)) { Op1C = Op0; BO = dyn_cast(Op1); } Value *Neg = dyn_castNegVal(Op1C); if (BO && BO->hasOneUse() && (BO->getOperand(1) == Op1C || BO->getOperand(1) == Neg) && (BO->getOpcode() == Instruction::UDiv || BO->getOpcode() == Instruction::SDiv)) { Value *Op0BO = BO->getOperand(0), *Op1BO = BO->getOperand(1); // If the division is exact, X % Y is zero. if (SDivOperator *SDiv = dyn_cast(BO)) if (SDiv->isExact()) { if (Op1BO == Op1C) return ReplaceInstUsesWith(I, Op0BO); return BinaryOperator::CreateNeg(Op0BO); } Value *Rem; if (BO->getOpcode() == Instruction::UDiv) Rem = Builder->CreateURem(Op0BO, Op1BO); else Rem = Builder->CreateSRem(Op0BO, Op1BO); Rem->takeName(BO); if (Op1BO == Op1C) return BinaryOperator::CreateSub(Op0BO, Rem); return BinaryOperator::CreateSub(Rem, Op0BO); } } /// i1 mul -> i1 and. if (I.getType()->isIntegerTy(1)) return BinaryOperator::CreateAnd(Op0, Op1); // X*(1 << Y) --> X << Y // (1 << Y)*X --> X << Y { Value *Y; if (match(Op0, m_Shl(m_One(), m_Value(Y)))) return BinaryOperator::CreateShl(Op1, Y); if (match(Op1, m_Shl(m_One(), m_Value(Y)))) return BinaryOperator::CreateShl(Op0, Y); } // If one of the operands of the multiply is a cast from a boolean value, then // we know the bool is either zero or one, so this is a 'masking' multiply. // X * Y (where Y is 0 or 1) -> X & (0-Y) if (!I.getType()->isVectorTy()) { // -2 is "-1 << 1" so it is all bits set except the low one. APInt Negative2(I.getType()->getPrimitiveSizeInBits(), (uint64_t)-2, true); Value *BoolCast = 0, *OtherOp = 0; if (MaskedValueIsZero(Op0, Negative2)) BoolCast = Op0, OtherOp = Op1; else if (MaskedValueIsZero(Op1, Negative2)) BoolCast = Op1, OtherOp = Op0; if (BoolCast) { Value *V = Builder->CreateSub(Constant::getNullValue(I.getType()), BoolCast, "tmp"); return BinaryOperator::CreateAnd(V, OtherOp); } } return Changed ? &I : 0; } Instruction *InstCombiner::visitFMul(BinaryOperator &I) { bool Changed = SimplifyCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); // Simplify mul instructions with a constant RHS... if (Constant *Op1C = dyn_cast(Op1)) { if (ConstantFP *Op1F = dyn_cast(Op1C)) { // "In IEEE floating point, x*1 is not equivalent to x for nans. However, // ANSI says we can drop signals, so we can do this anyway." (from GCC) if (Op1F->isExactlyValue(1.0)) return ReplaceInstUsesWith(I, Op0); // Eliminate 'fmul double %X, 1.0' } else if (Op1C->getType()->isVectorTy()) { if (ConstantVector *Op1V = dyn_cast(Op1C)) { // As above, vector X*splat(1.0) -> X in all defined cases. if (Constant *Splat = Op1V->getSplatValue()) { if (ConstantFP *F = dyn_cast(Splat)) if (F->isExactlyValue(1.0)) return ReplaceInstUsesWith(I, Op0); } } } // Try to fold constant mul into select arguments. if (SelectInst *SI = dyn_cast(Op0)) if (Instruction *R = FoldOpIntoSelect(I, SI)) return R; if (isa(Op0)) if (Instruction *NV = FoldOpIntoPhi(I)) return NV; } if (Value *Op0v = dyn_castFNegVal(Op0)) // -X * -Y = X*Y if (Value *Op1v = dyn_castFNegVal(Op1)) return BinaryOperator::CreateFMul(Op0v, Op1v); return Changed ? &I : 0; } /// SimplifyDivRemOfSelect - Try to fold a divide or remainder of a select /// instruction. bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) { SelectInst *SI = cast(I.getOperand(1)); // div/rem X, (Cond ? 0 : Y) -> div/rem X, Y int NonNullOperand = -1; if (Constant *ST = dyn_cast(SI->getOperand(1))) if (ST->isNullValue()) NonNullOperand = 2; // div/rem X, (Cond ? Y : 0) -> div/rem X, Y if (Constant *ST = dyn_cast(SI->getOperand(2))) if (ST->isNullValue()) NonNullOperand = 1; if (NonNullOperand == -1) return false; Value *SelectCond = SI->getOperand(0); // Change the div/rem to use 'Y' instead of the select. I.setOperand(1, SI->getOperand(NonNullOperand)); // Okay, we know we replace the operand of the div/rem with 'Y' with no // problem. However, the select, or the condition of the select may have // multiple uses. Based on our knowledge that the operand must be non-zero, // propagate the known value for the select into other uses of it, and // propagate a known value of the condition into its other users. // If the select and condition only have a single use, don't bother with this, // early exit. if (SI->use_empty() && SelectCond->hasOneUse()) return true; // Scan the current block backward, looking for other uses of SI. BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin(); while (BBI != BBFront) { --BBI; // If we found a call to a function, we can't assume it will return, so // information from below it cannot be propagated above it. if (isa(BBI) && !isa(BBI)) break; // Replace uses of the select or its condition with the known values. for (Instruction::op_iterator I = BBI->op_begin(), E = BBI->op_end(); I != E; ++I) { if (*I == SI) { *I = SI->getOperand(NonNullOperand); Worklist.Add(BBI); } else if (*I == SelectCond) { *I = NonNullOperand == 1 ? ConstantInt::getTrue(BBI->getContext()) : ConstantInt::getFalse(BBI->getContext()); Worklist.Add(BBI); } } // If we past the instruction, quit looking for it. if (&*BBI == SI) SI = 0; if (&*BBI == SelectCond) SelectCond = 0; // If we ran out of things to eliminate, break out of the loop. if (SelectCond == 0 && SI == 0) break; } return true; } /// This function implements the transforms on div instructions that work /// regardless of the kind of div instruction it is (udiv, sdiv, or fdiv). It is /// used by the visitors to those instructions. /// @brief Transforms common to all three div instructions Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); // undef / X -> 0 for integer. // undef / X -> undef for FP (the undef could be a snan). if (isa(Op0)) { if (Op0->getType()->isFPOrFPVectorTy()) return ReplaceInstUsesWith(I, Op0); return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); } // X / undef -> undef if (isa(Op1)) return ReplaceInstUsesWith(I, Op1); return 0; } /// This function implements the transforms common to both integer division /// instructions (udiv and sdiv). It is called by the visitors to those integer /// division instructions. /// @brief Common integer divide transforms Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); // (sdiv X, X) --> 1 (udiv X, X) --> 1 if (Op0 == Op1) { if (const VectorType *Ty = dyn_cast(I.getType())) { Constant *CI = ConstantInt::get(Ty->getElementType(), 1); std::vector Elts(Ty->getNumElements(), CI); return ReplaceInstUsesWith(I, ConstantVector::get(Elts)); } Constant *CI = ConstantInt::get(I.getType(), 1); return ReplaceInstUsesWith(I, CI); } if (Instruction *Common = commonDivTransforms(I)) return Common; // Handle cases involving: [su]div X, (select Cond, Y, Z) // This does not apply for fdiv. if (isa(Op1) && SimplifyDivRemOfSelect(I)) return &I; if (ConstantInt *RHS = dyn_cast(Op1)) { // div X, 1 == X if (RHS->equalsInt(1)) return ReplaceInstUsesWith(I, Op0); // (X / C1) / C2 -> X / (C1*C2) if (Instruction *LHS = dyn_cast(Op0)) if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode()) if (ConstantInt *LHSRHS = dyn_cast(LHS->getOperand(1))) { if (MultiplyOverflows(RHS, LHSRHS, I.getOpcode()==Instruction::SDiv)) return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); else return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0), ConstantExpr::getMul(RHS, LHSRHS)); } if (!RHS->isZero()) { // avoid X udiv 0 if (SelectInst *SI = dyn_cast(Op0)) if (Instruction *R = FoldOpIntoSelect(I, SI)) return R; if (isa(Op0)) if (Instruction *NV = FoldOpIntoPhi(I)) return NV; } } // 0 / X == 0, we don't need to preserve faults! if (ConstantInt *LHS = dyn_cast(Op0)) if (LHS->equalsInt(0)) return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); // It can't be division by zero, hence it must be division by one. if (I.getType()->isIntegerTy(1)) return ReplaceInstUsesWith(I, Op0); if (ConstantVector *Op1V = dyn_cast(Op1)) { if (ConstantInt *X = cast_or_null(Op1V->getSplatValue())) // div X, 1 == X if (X->isOne()) return ReplaceInstUsesWith(I, Op0); } return 0; } Instruction *InstCombiner::visitUDiv(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); // Handle the integer div common cases if (Instruction *Common = commonIDivTransforms(I)) return Common; if (ConstantInt *C = dyn_cast(Op1)) { // X udiv 2^C -> X >> C // Check to see if this is an unsigned division with an exact power of 2, // if so, convert to a right shift. if (C->getValue().isPowerOf2()) // 0 not included in isPowerOf2 return BinaryOperator::CreateLShr(Op0, ConstantInt::get(Op0->getType(), C->getValue().logBase2())); // X udiv C, where C >= signbit if (C->getValue().isNegative()) { Value *IC = Builder->CreateICmpULT( Op0, C); return SelectInst::Create(IC, Constant::getNullValue(I.getType()), ConstantInt::get(I.getType(), 1)); } } // X udiv (C1 << N), where C1 is "1< X >> (N+C2) if (BinaryOperator *RHSI = dyn_cast(I.getOperand(1))) { if (RHSI->getOpcode() == Instruction::Shl && isa(RHSI->getOperand(0))) { const APInt& C1 = cast(RHSI->getOperand(0))->getValue(); if (C1.isPowerOf2()) { Value *N = RHSI->getOperand(1); const Type *NTy = N->getType(); if (uint32_t C2 = C1.logBase2()) N = Builder->CreateAdd(N, ConstantInt::get(NTy, C2), "tmp"); return BinaryOperator::CreateLShr(Op0, N); } } } // udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2) // where C1&C2 are powers of two. if (SelectInst *SI = dyn_cast(Op1)) if (ConstantInt *STO = dyn_cast(SI->getOperand(1))) if (ConstantInt *SFO = dyn_cast(SI->getOperand(2))) { const APInt &TVA = STO->getValue(), &FVA = SFO->getValue(); if (TVA.isPowerOf2() && FVA.isPowerOf2()) { // Compute the shift amounts uint32_t TSA = TVA.logBase2(), FSA = FVA.logBase2(); // Construct the "on true" case of the select Constant *TC = ConstantInt::get(Op0->getType(), TSA); Value *TSI = Builder->CreateLShr(Op0, TC, SI->getName()+".t"); // Construct the "on false" case of the select Constant *FC = ConstantInt::get(Op0->getType(), FSA); Value *FSI = Builder->CreateLShr(Op0, FC, SI->getName()+".f"); // construct the select instruction and return it. return SelectInst::Create(SI->getOperand(0), TSI, FSI, SI->getName()); } } return 0; } Instruction *InstCombiner::visitSDiv(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); // Handle the integer div common cases if (Instruction *Common = commonIDivTransforms(I)) return Common; if (ConstantInt *RHS = dyn_cast(Op1)) { // sdiv X, -1 == -X if (RHS->isAllOnesValue()) return BinaryOperator::CreateNeg(Op0); // sdiv X, C --> ashr X, log2(C) if (cast(&I)->isExact() && RHS->getValue().isNonNegative() && RHS->getValue().isPowerOf2()) { Value *ShAmt = llvm::ConstantInt::get(RHS->getType(), RHS->getValue().exactLogBase2()); return BinaryOperator::CreateAShr(Op0, ShAmt, I.getName()); } // -X/C --> X/-C provided the negation doesn't overflow. if (SubOperator *Sub = dyn_cast(Op0)) if (isa(Sub->getOperand(0)) && cast(Sub->getOperand(0))->isNullValue() && Sub->hasNoSignedWrap()) return BinaryOperator::CreateSDiv(Sub->getOperand(1), ConstantExpr::getNeg(RHS)); } // If the sign bits of both operands are zero (i.e. we can prove they are // unsigned inputs), turn this into a udiv. if (I.getType()->isIntegerTy()) { APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits())); if (MaskedValueIsZero(Op0, Mask)) { if (MaskedValueIsZero(Op1, Mask)) { // X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set return BinaryOperator::CreateUDiv(Op0, Op1, I.getName()); } ConstantInt *ShiftedInt; if (match(Op1, m_Shl(m_ConstantInt(ShiftedInt), m_Value())) && ShiftedInt->getValue().isPowerOf2()) { // X sdiv (1 << Y) -> X udiv (1 << Y) ( -> X u>> Y) // Safe because the only negative value (1 << Y) can take on is // INT_MIN, and X sdiv INT_MIN == X udiv INT_MIN == 0 if X doesn't have // the sign bit set. return BinaryOperator::CreateUDiv(Op0, Op1, I.getName()); } } } return 0; } Instruction *InstCombiner::visitFDiv(BinaryOperator &I) { return commonDivTransforms(I); } /// This function implements the transforms on rem instructions that work /// regardless of the kind of rem instruction it is (urem, srem, or frem). It /// is used by the visitors to those instructions. /// @brief Transforms common to all three rem instructions Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); if (isa(Op0)) { // undef % X -> 0 if (I.getType()->isFPOrFPVectorTy()) return ReplaceInstUsesWith(I, Op0); // X % undef -> undef (could be SNaN) return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); } if (isa(Op1)) return ReplaceInstUsesWith(I, Op1); // X % undef -> undef // Handle cases involving: rem X, (select Cond, Y, Z) if (isa(Op1) && SimplifyDivRemOfSelect(I)) return &I; return 0; } /// This function implements the transforms common to both integer remainder /// instructions (urem and srem). It is called by the visitors to those integer /// remainder instructions. /// @brief Common integer remainder transforms Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); if (Instruction *common = commonRemTransforms(I)) return common; // 0 % X == 0 for integer, we don't need to preserve faults! if (Constant *LHS = dyn_cast(Op0)) if (LHS->isNullValue()) return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); if (ConstantInt *RHS = dyn_cast(Op1)) { // X % 0 == undef, we don't need to preserve faults! if (RHS->equalsInt(0)) return ReplaceInstUsesWith(I, UndefValue::get(I.getType())); if (RHS->equalsInt(1)) // X % 1 == 0 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); if (Instruction *Op0I = dyn_cast(Op0)) { if (SelectInst *SI = dyn_cast(Op0I)) { if (Instruction *R = FoldOpIntoSelect(I, SI)) return R; } else if (isa(Op0I)) { if (Instruction *NV = FoldOpIntoPhi(I)) return NV; } // See if we can fold away this rem instruction. if (SimplifyDemandedInstructionBits(I)) return &I; } } return 0; } Instruction *InstCombiner::visitURem(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); if (Instruction *common = commonIRemTransforms(I)) return common; if (ConstantInt *RHS = dyn_cast(Op1)) { // X urem C^2 -> X and C // Check to see if this is an unsigned remainder with an exact power of 2, // if so, convert to a bitwise and. if (ConstantInt *C = dyn_cast(RHS)) if (C->getValue().isPowerOf2()) return BinaryOperator::CreateAnd(Op0, SubOne(C)); } if (Instruction *RHSI = dyn_cast(I.getOperand(1))) { // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1) if (RHSI->getOpcode() == Instruction::Shl && isa(RHSI->getOperand(0))) { if (cast(RHSI->getOperand(0))->getValue().isPowerOf2()) { Constant *N1 = Constant::getAllOnesValue(I.getType()); Value *Add = Builder->CreateAdd(RHSI, N1, "tmp"); return BinaryOperator::CreateAnd(Op0, Add); } } } // urem X, (select Cond, 2^C1, 2^C2) --> select Cond, (and X, C1), (and X, C2) // where C1&C2 are powers of two. if (SelectInst *SI = dyn_cast(Op1)) { if (ConstantInt *STO = dyn_cast(SI->getOperand(1))) if (ConstantInt *SFO = dyn_cast(SI->getOperand(2))) { // STO == 0 and SFO == 0 handled above. if ((STO->getValue().isPowerOf2()) && (SFO->getValue().isPowerOf2())) { Value *TrueAnd = Builder->CreateAnd(Op0, SubOne(STO), SI->getName()+".t"); Value *FalseAnd = Builder->CreateAnd(Op0, SubOne(SFO), SI->getName()+".f"); return SelectInst::Create(SI->getOperand(0), TrueAnd, FalseAnd); } } } return 0; } Instruction *InstCombiner::visitSRem(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); // Handle the integer rem common cases if (Instruction *Common = commonIRemTransforms(I)) return Common; if (Value *RHSNeg = dyn_castNegVal(Op1)) if (!isa(RHSNeg) || (isa(RHSNeg) && cast(RHSNeg)->getValue().isStrictlyPositive())) { // X % -Y -> X % Y Worklist.AddValue(I.getOperand(1)); I.setOperand(1, RHSNeg); return &I; } // If the sign bits of both operands are zero (i.e. we can prove they are // unsigned inputs), turn this into a urem. if (I.getType()->isIntegerTy()) { APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits())); if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) { // X srem Y -> X urem Y, iff X and Y don't have sign bit set return BinaryOperator::CreateURem(Op0, Op1, I.getName()); } } // If it's a constant vector, flip any negative values positive. if (ConstantVector *RHSV = dyn_cast(Op1)) { unsigned VWidth = RHSV->getNumOperands(); bool hasNegative = false; for (unsigned i = 0; !hasNegative && i != VWidth; ++i) if (ConstantInt *RHS = dyn_cast(RHSV->getOperand(i))) if (RHS->getValue().isNegative()) hasNegative = true; if (hasNegative) { std::vector Elts(VWidth); for (unsigned i = 0; i != VWidth; ++i) { if (ConstantInt *RHS = dyn_cast(RHSV->getOperand(i))) { if (RHS->getValue().isNegative()) Elts[i] = cast(ConstantExpr::getNeg(RHS)); else Elts[i] = RHS; } } Constant *NewRHSV = ConstantVector::get(Elts); if (NewRHSV != RHSV) { Worklist.AddValue(I.getOperand(1)); I.setOperand(1, NewRHSV); return &I; } } } return 0; } Instruction *InstCombiner::visitFRem(BinaryOperator &I) { return commonRemTransforms(I); }