diff options
Diffstat (limited to 'lib/Transforms/InstCombine/InstCombineMulDivRem.cpp')
-rw-r--r-- | lib/Transforms/InstCombine/InstCombineMulDivRem.cpp | 315 |
1 files changed, 121 insertions, 194 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp index b3974e8..d1a1fd6 100644 --- a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp +++ b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp @@ -14,26 +14,22 @@ #include "InstCombine.h" #include "llvm/IntrinsicInst.h" +#include "llvm/Analysis/InstructionSimplify.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); + LHSExt = LHSExt.sext(W * 2); + RHSExt = RHSExt.sext(W * 2); } else { - LHSExt.zext(W * 2); - RHSExt.zext(W * 2); + LHSExt = LHSExt.zext(W * 2); + RHSExt = RHSExt.zext(W * 2); } APInt MulExt = LHSExt * RHSExt; @@ -47,62 +43,48 @@ static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) { } Instruction *InstCombiner::visitMul(BinaryOperator &I) { - bool Changed = SimplifyCommutative(I); + bool Changed = SimplifyAssociativeOrCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); - if (isa<UndefValue>(Op1)) // undef * X -> 0 - return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); + if (Value *V = SimplifyMulInst(Op0, Op1, TD)) + return ReplaceInstUsesWith(I, V); - // Simplify mul instructions with a constant RHS. - if (Constant *Op1C = dyn_cast<Constant>(Op1)) { - if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1C)) { - - // ((X << C1)*C2) == (X * (C2 << C1)) - 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)); - - 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<ConstantInt>(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<ConstantVector>(Op1C)) { - if (Op1V->isAllOnesValue()) // X * -1 == 0 - X - return BinaryOperator::CreateNeg(Op0, I.getName()); + if (Value *V = SimplifyUsingDistributiveLaws(I)) + return ReplaceInstUsesWith(I, V); - // As above, vector X*splat(1.0) -> X in all defined cases. - if (Constant *Splat = Op1V->getSplatValue()) { - if (ConstantInt *CI = dyn_cast<ConstantInt>(Splat)) - if (CI->equalsInt(1)) - return ReplaceInstUsesWith(I, Op0); - } - } + if (match(Op1, m_AllOnes())) // X * -1 == 0 - X + return BinaryOperator::CreateNeg(Op0, I.getName()); + + if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { + + // ((X << C1)*C2) == (X * (C2 << C1)) + 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()) { // Replace X*(2^C) with X << C + 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; } - if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) - if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() && - isa<ConstantInt>(Op0I->getOperand(1)) && isa<ConstantInt>(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); - + // Canonicalize (X+C1)*CI -> X*CI+C1*CI. + { 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)); } - + } + } + + // Simplify mul instructions with a constant RHS. + if (isa<Constant>(Op1)) { // Try to fold constant mul into select arguments. if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) if (Instruction *R = FoldOpIntoSelect(I, SI)) @@ -135,8 +117,8 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { 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<SDivOperator>(BO)) + // If the division is exact, X % Y is zero, so we end up with X or -X. + if (PossiblyExactOperator *SDiv = dyn_cast<PossiblyExactOperator>(BO)) if (SDiv->isExact()) { if (Op1BO == Op1C) return ReplaceInstUsesWith(I, Op0BO); @@ -194,7 +176,7 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { } Instruction *InstCombiner::visitFMul(BinaryOperator &I) { - bool Changed = SimplifyCommutative(I); + bool Changed = SimplifyAssociativeOrCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); // Simplify mul instructions with a constant RHS... @@ -304,28 +286,6 @@ bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) { } -/// 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<UndefValue>(Op0)) { - if (Op0->getType()->isFPOrFPVectorTy()) - return ReplaceInstUsesWith(I, Op0); - return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); - } - - // X / undef -> undef - if (isa<UndefValue>(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. @@ -333,31 +293,12 @@ Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) { 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<VectorType>(I.getType())) { - Constant *CI = ConstantInt::get(Ty->getElementType(), 1); - std::vector<Constant*> 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<SelectInst>(Op1) && SimplifyDivRemOfSelect(I)) return &I; if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) { - // div X, 1 == X - if (RHS->equalsInt(1)) - return ReplaceInstUsesWith(I, Op0); - // (X / C1) / C2 -> X / (C1*C2) if (Instruction *LHS = dyn_cast<Instruction>(Op0)) if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode()) @@ -365,9 +306,8 @@ Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) { 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)); + return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0), + ConstantExpr::getMul(RHS, LHSRHS)); } if (!RHS->isZero()) { // avoid X udiv 0 @@ -380,20 +320,13 @@ Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) { } } - // 0 / X == 0, we don't need to preserve faults! - if (ConstantInt *LHS = dyn_cast<ConstantInt>(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<ConstantVector>(Op1)) { - if (ConstantInt *X = cast_or_null<ConstantInt>(Op1V->getSplatValue())) - // div X, 1 == X - if (X->isOne()) - return ReplaceInstUsesWith(I, Op0); + // (X - (X rem Y)) / Y -> X / Y; usually originates as ((X / Y) * Y) / Y + Value *X = 0, *Z = 0; + if (match(Op0, m_Sub(m_Value(X), m_Value(Z)))) { // (X - Z) / Y; Y = Op1 + 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; @@ -402,6 +335,9 @@ Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) { 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); + // Handle the integer div common cases if (Instruction *Common = commonIDivTransforms(I)) return Common; @@ -410,60 +346,59 @@ Instruction *InstCombiner::visitUDiv(BinaryOperator &I) { // 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, + if (C->getValue().isPowerOf2()) { // 0 not included in isPowerOf2 + BinaryOperator *LShr = + BinaryOperator::CreateLShr(Op0, ConstantInt::get(Op0->getType(), C->getValue().logBase2())); + if (I.isExact()) LShr->setIsExact(); + return LShr; + } // X udiv C, where C >= signbit if (C->getValue().isNegative()) { - Value *IC = Builder->CreateICmpULT( Op0, C); + 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<<C2" --> X >> (N+C2) - if (BinaryOperator *RHSI = dyn_cast<BinaryOperator>(I.getOperand(1))) { - if (RHSI->getOpcode() == Instruction::Shl && - isa<ConstantInt>(RHSI->getOperand(0))) { - const APInt& C1 = cast<ConstantInt>(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); - } + { 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); } } // 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<SelectInst>(Op1)) - if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1))) - if (ConstantInt *SFO = dyn_cast<ConstantInt>(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"); + { Value *Cond; const APInt *C1, *C2; + if (match(Op1, m_Select(m_Value(Cond), m_Power2(C1), m_Power2(C2)))) { + // Construct the "on true" case of the select + Value *TSI = Builder->CreateLShr(Op0, C1->logBase2(), Op1->getName()+".t", + I.isExact()); - // 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()); - } - } + // Construct the "on false" case of the select + Value *FSI = Builder->CreateLShr(Op0, C2->logBase2(), Op1->getName()+".f", + I.isExact()); + + // construct the select instruction and return it. + return SelectInst::Create(Cond, TSI, FSI); + } + } 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); + // Handle the integer div common cases if (Instruction *Common = commonIDivTransforms(I)) return Common; @@ -473,20 +408,17 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) { if (RHS->isAllOnesValue()) return BinaryOperator::CreateNeg(Op0); - // sdiv X, C --> ashr X, log2(C) - if (cast<SDivOperator>(&I)->isExact() && - RHS->getValue().isNonNegative() && + // sdiv X, C --> ashr exact X, log2(C) + if (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()); + return BinaryOperator::CreateExactAShr(Op0, ShAmt, I.getName()); } // -X/C --> X/-C provided the negation doesn't overflow. if (SubOperator *Sub = dyn_cast<SubOperator>(Op0)) - if (isa<Constant>(Sub->getOperand(0)) && - cast<Constant>(Sub->getOperand(0))->isNullValue() && - Sub->hasNoSignedWrap()) + if (match(Sub->getOperand(0), m_Zero()) && Sub->hasNoSignedWrap()) return BinaryOperator::CreateSDiv(Sub->getOperand(1), ConstantExpr::getNeg(RHS)); } @@ -500,9 +432,8 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) { // 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()) { + + if (match(Op1, m_Shl(m_Power2(), m_Value()))) { // 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 @@ -516,7 +447,12 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) { } Instruction *InstCombiner::visitFDiv(BinaryOperator &I) { - return commonDivTransforms(I); + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + if (Value *V = SimplifyFDivInst(Op0, Op1, TD)) + return ReplaceInstUsesWith(I, V); + + return 0; } /// This function implements the transforms on rem instructions that work @@ -551,6 +487,10 @@ Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) { if (Instruction *common = commonRemTransforms(I)) return common; + // X % X == 0 + if (Op0 == Op1) + return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); + // 0 % X == 0 for integer, we don't need to preserve faults! if (Constant *LHS = dyn_cast<Constant>(Op0)) if (LHS->isNullValue()) @@ -588,42 +528,29 @@ Instruction *InstCombiner::visitURem(BinaryOperator &I) { if (Instruction *common = commonIRemTransforms(I)) return common; - if (ConstantInt *RHS = dyn_cast<ConstantInt>(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<ConstantInt>(RHS)) - if (C->getValue().isPowerOf2()) - return BinaryOperator::CreateAnd(Op0, SubOne(C)); + // X urem C^2 -> X and C-1 + { const APInt *C; + if (match(Op1, m_Power2(C))) + return BinaryOperator::CreateAnd(Op0, + ConstantInt::get(I.getType(), *C-1)); } - if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) { - // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1) - if (RHSI->getOpcode() == Instruction::Shl && - isa<ConstantInt>(RHSI->getOperand(0))) { - if (cast<ConstantInt>(RHSI->getOperand(0))->getValue().isPowerOf2()) { - Constant *N1 = Constant::getAllOnesValue(I.getType()); - Value *Add = Builder->CreateAdd(RHSI, N1, "tmp"); - return BinaryOperator::CreateAnd(Op0, Add); - } - } + // Turn A % (C << N), where C is 2^k, into A & ((C << N)-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); } - // 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<SelectInst>(Op1)) { - if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1))) - if (ConstantInt *SFO = dyn_cast<ConstantInt>(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); - } - } + // urem X, (select Cond, 2^C1, 2^C2) --> + // select Cond, (and X, C1-1), (and X, C2-1) + // when C1&C2 are powers of two. + { 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); + } } return 0; |