InstCombineMulDivRem.cpp [plain text]
#include "InstCombine.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Support/PatternMatch.h"
using namespace llvm;
using namespace PatternMatch;
static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
uint32_t W = C1->getBitWidth();
APInt LHSExt = C1->getValue(), RHSExt = C2->getValue();
if (sign) {
LHSExt = LHSExt.sext(W * 2);
RHSExt = RHSExt.sext(W * 2);
} else {
LHSExt = LHSExt.zext(W * 2);
RHSExt = 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 = SimplifyAssociativeOrCommutative(I);
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Value *V = SimplifyMulInst(Op0, Op1, TD))
return ReplaceInstUsesWith(I, V);
if (Value *V = SimplifyUsingDistributiveLaws(I))
return ReplaceInstUsesWith(I, V);
if (match(Op1, m_AllOnes())) return BinaryOperator::CreateNeg(Op0, I.getName());
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0))
if (SI->getOpcode() == Instruction::Shl)
if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
return BinaryOperator::CreateMul(SI->getOperand(0),
ConstantExpr::getShl(CI, ShOp));
const APInt &Val = CI->getValue();
if (Val.isPowerOf2()) { Constant *NewCst = ConstantInt::get(Op0->getType(), Val.logBase2());
BinaryOperator *Shl = BinaryOperator::CreateShl(Op0, NewCst);
if (I.hasNoSignedWrap()) Shl->setHasNoSignedWrap();
if (I.hasNoUnsignedWrap()) Shl->setHasNoUnsignedWrap();
return Shl;
}
{ Value *X; ConstantInt *C1;
if (Op0->hasOneUse() &&
match(Op0, m_Add(m_Value(X), m_ConstantInt(C1)))) {
Value *Add = Builder->CreateMul(X, CI, "tmp");
return BinaryOperator::CreateAdd(Add, Builder->CreateMul(C1, CI));
}
}
}
if (isa<Constant>(Op1)) {
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
if (Instruction *R = FoldOpIntoSelect(I, SI))
return R;
if (isa<PHINode>(Op0))
if (Instruction *NV = FoldOpIntoPhi(I))
return NV;
}
if (Value *Op0v = dyn_castNegVal(Op0)) if (Value *Op1v = dyn_castNegVal(Op1))
return BinaryOperator::CreateMul(Op0v, Op1v);
{
Value *Op1C = Op1;
BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0);
if (!BO ||
(BO->getOpcode() != Instruction::UDiv &&
BO->getOpcode() != Instruction::SDiv)) {
Op1C = Op0;
BO = dyn_cast<BinaryOperator>(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 (PossiblyExactOperator *SDiv = dyn_cast<PossiblyExactOperator>(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);
}
}
if (I.getType()->isIntegerTy(1))
return BinaryOperator::CreateAnd(Op0, Op1);
{
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 (!I.getType()->isVectorTy()) {
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 = SimplifyAssociativeOrCommutative(I);
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1C)) {
if (Op1F->isExactlyValue(1.0))
return ReplaceInstUsesWith(I, Op0); } else if (Op1C->getType()->isVectorTy()) {
if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1C)) {
if (Constant *Splat = Op1V->getSplatValue()) {
if (ConstantFP *F = dyn_cast<ConstantFP>(Splat))
if (F->isExactlyValue(1.0))
return ReplaceInstUsesWith(I, Op0);
}
}
}
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
if (Instruction *R = FoldOpIntoSelect(I, SI))
return R;
if (isa<PHINode>(Op0))
if (Instruction *NV = FoldOpIntoPhi(I))
return NV;
}
if (Value *Op0v = dyn_castFNegVal(Op0)) if (Value *Op1v = dyn_castFNegVal(Op1))
return BinaryOperator::CreateFMul(Op0v, Op1v);
return Changed ? &I : 0;
}
bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) {
SelectInst *SI = cast<SelectInst>(I.getOperand(1));
int NonNullOperand = -1;
if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
if (ST->isNullValue())
NonNullOperand = 2;
if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
if (ST->isNullValue())
NonNullOperand = 1;
if (NonNullOperand == -1)
return false;
Value *SelectCond = SI->getOperand(0);
I.setOperand(1, SI->getOperand(NonNullOperand));
if (SI->use_empty() && SelectCond->hasOneUse())
return true;
BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin();
while (BBI != BBFront) {
--BBI;
if (isa<CallInst>(BBI) && !isa<IntrinsicInst>(BBI))
break;
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 (&*BBI == SI)
SI = 0;
if (&*BBI == SelectCond)
SelectCond = 0;
if (SelectCond == 0 && SI == 0)
break;
}
return true;
}
Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
return &I;
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
if (Instruction *LHS = dyn_cast<Instruction>(Op0))
if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
if (MultiplyOverflows(RHS, LHSRHS,
I.getOpcode()==Instruction::SDiv))
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0),
ConstantExpr::getMul(RHS, LHSRHS));
}
if (!RHS->isZero()) { if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
if (Instruction *R = FoldOpIntoSelect(I, SI))
return R;
if (isa<PHINode>(Op0))
if (Instruction *NV = FoldOpIntoPhi(I))
return NV;
}
}
if (SimplifyDemandedInstructionBits(I))
return &I;
Value *X = 0, *Z = 0;
if (match(Op0, m_Sub(m_Value(X), m_Value(Z)))) { bool isSigned = I.getOpcode() == Instruction::SDiv;
if ((isSigned && match(Z, m_SRem(m_Specific(X), m_Specific(Op1)))) ||
(!isSigned && match(Z, m_URem(m_Specific(X), m_Specific(Op1)))))
return BinaryOperator::Create(I.getOpcode(), X, Op1);
}
return 0;
}
static Value *dyn_castZExtVal(Value *V, const Type *Ty) {
if (ZExtInst *Z = dyn_cast<ZExtInst>(V)) {
if (Z->getSrcTy() == Ty)
return Z->getOperand(0);
} else if (ConstantInt *C = dyn_cast<ConstantInt>(V)) {
if (C->getValue().getActiveBits() <= cast<IntegerType>(Ty)->getBitWidth())
return ConstantExpr::getTrunc(C, Ty);
}
return 0;
}
Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Value *V = SimplifyUDivInst(Op0, Op1, TD))
return ReplaceInstUsesWith(I, V);
if (Instruction *Common = commonIDivTransforms(I))
return Common;
if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
if (C->getValue().isPowerOf2()) { BinaryOperator *LShr =
BinaryOperator::CreateLShr(Op0,
ConstantInt::get(Op0->getType(), C->getValue().logBase2()));
if (I.isExact()) LShr->setIsExact();
return LShr;
}
if (C->getValue().isNegative()) {
Value *IC = Builder->CreateICmpULT(Op0, C);
return SelectInst::Create(IC, Constant::getNullValue(I.getType()),
ConstantInt::get(I.getType(), 1));
}
}
{ const APInt *CI; Value *N;
if (match(Op1, m_Shl(m_Power2(CI), m_Value(N)))) {
if (*CI != 1)
N = Builder->CreateAdd(N, ConstantInt::get(I.getType(), CI->logBase2()),
"tmp");
if (I.isExact())
return BinaryOperator::CreateExactLShr(Op0, N);
return BinaryOperator::CreateLShr(Op0, N);
}
}
{ Value *Cond; const APInt *C1, *C2;
if (match(Op1, m_Select(m_Value(Cond), m_Power2(C1), m_Power2(C2)))) {
Value *TSI = Builder->CreateLShr(Op0, C1->logBase2(), Op1->getName()+".t",
I.isExact());
Value *FSI = Builder->CreateLShr(Op0, C2->logBase2(), Op1->getName()+".f",
I.isExact());
return SelectInst::Create(Cond, TSI, FSI);
}
}
if (ZExtInst *ZOp0 = dyn_cast<ZExtInst>(Op0))
if (Value *ZOp1 = dyn_castZExtVal(Op1, ZOp0->getSrcTy()))
return new ZExtInst(Builder->CreateUDiv(ZOp0->getOperand(0), ZOp1, "div",
I.isExact()),
I.getType());
return 0;
}
Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Value *V = SimplifySDivInst(Op0, Op1, TD))
return ReplaceInstUsesWith(I, V);
if (Instruction *Common = commonIDivTransforms(I))
return Common;
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
if (RHS->isAllOnesValue())
return BinaryOperator::CreateNeg(Op0);
if (I.isExact() && RHS->getValue().isNonNegative() &&
RHS->getValue().isPowerOf2()) {
Value *ShAmt = llvm::ConstantInt::get(RHS->getType(),
RHS->getValue().exactLogBase2());
return BinaryOperator::CreateExactAShr(Op0, ShAmt, I.getName());
}
if (SubOperator *Sub = dyn_cast<SubOperator>(Op0))
if (match(Sub->getOperand(0), m_Zero()) && Sub->hasNoSignedWrap())
return BinaryOperator::CreateSDiv(Sub->getOperand(1),
ConstantExpr::getNeg(RHS));
}
if (I.getType()->isIntegerTy()) {
APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
if (MaskedValueIsZero(Op0, Mask)) {
if (MaskedValueIsZero(Op1, Mask)) {
return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
}
if (match(Op1, m_Shl(m_Power2(), m_Value()))) {
return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
}
}
}
return 0;
}
Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Value *V = SimplifyFDivInst(Op0, Op1, TD))
return ReplaceInstUsesWith(I, V);
if (ConstantFP *Op1C = dyn_cast<ConstantFP>(Op1)) {
const APFloat &Op1F = Op1C->getValueAPF();
APFloat Reciprocal(Op1F.getSemantics());
if (Op1F.getExactInverse(&Reciprocal)) {
ConstantFP *RFP = ConstantFP::get(Builder->getContext(), Reciprocal);
return BinaryOperator::CreateFMul(Op0, RFP);
}
}
return 0;
}
Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
return &I;
if (isa<ConstantInt>(Op1)) {
if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
if (Instruction *R = FoldOpIntoSelect(I, SI))
return R;
} else if (isa<PHINode>(Op0I)) {
if (Instruction *NV = FoldOpIntoPhi(I))
return NV;
}
if (SimplifyDemandedInstructionBits(I))
return &I;
}
}
return 0;
}
Instruction *InstCombiner::visitURem(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Value *V = SimplifyURemInst(Op0, Op1, TD))
return ReplaceInstUsesWith(I, V);
if (Instruction *common = commonIRemTransforms(I))
return common;
{ const APInt *C;
if (match(Op1, m_Power2(C)))
return BinaryOperator::CreateAnd(Op0,
ConstantInt::get(I.getType(), *C-1));
}
if (match(Op1, m_Shl(m_Power2(), m_Value()))) {
Constant *N1 = Constant::getAllOnesValue(I.getType());
Value *Add = Builder->CreateAdd(Op1, N1, "tmp");
return BinaryOperator::CreateAnd(Op0, Add);
}
{ Value *Cond; const APInt *C1, *C2;
if (match(Op1, m_Select(m_Value(Cond), m_Power2(C1), m_Power2(C2)))) {
Value *TrueAnd = Builder->CreateAnd(Op0, *C1-1, Op1->getName()+".t");
Value *FalseAnd = Builder->CreateAnd(Op0, *C2-1, Op1->getName()+".f");
return SelectInst::Create(Cond, TrueAnd, FalseAnd);
}
}
if (ZExtInst *ZOp0 = dyn_cast<ZExtInst>(Op0))
if (Value *ZOp1 = dyn_castZExtVal(Op1, ZOp0->getSrcTy()))
return new ZExtInst(Builder->CreateURem(ZOp0->getOperand(0), ZOp1),
I.getType());
return 0;
}
Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Value *V = SimplifySRemInst(Op0, Op1, TD))
return ReplaceInstUsesWith(I, V);
if (Instruction *Common = commonIRemTransforms(I))
return Common;
if (Value *RHSNeg = dyn_castNegVal(Op1))
if (!isa<Constant>(RHSNeg) ||
(isa<ConstantInt>(RHSNeg) &&
cast<ConstantInt>(RHSNeg)->getValue().isStrictlyPositive())) {
Worklist.AddValue(I.getOperand(1));
I.setOperand(1, RHSNeg);
return &I;
}
if (I.getType()->isIntegerTy()) {
APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
return BinaryOperator::CreateURem(Op0, Op1, I.getName());
}
}
if (ConstantVector *RHSV = dyn_cast<ConstantVector>(Op1)) {
unsigned VWidth = RHSV->getNumOperands();
bool hasNegative = false;
for (unsigned i = 0; !hasNegative && i != VWidth; ++i)
if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i)))
if (RHS->getValue().isNegative())
hasNegative = true;
if (hasNegative) {
std::vector<Constant *> Elts(VWidth);
for (unsigned i = 0; i != VWidth; ++i) {
if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i))) {
if (RHS->getValue().isNegative())
Elts[i] = cast<ConstantInt>(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) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Value *V = SimplifyFRemInst(Op0, Op1, TD))
return ReplaceInstUsesWith(I, V);
if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
return &I;
return 0;
}