| //===- InstCombineAddSub.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 add, fadd, sub, and fsub. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "InstCombine.h" |
| #include "llvm/Analysis/InstructionSimplify.h" |
| #include "llvm/Target/TargetData.h" |
| #include "llvm/Support/GetElementPtrTypeIterator.h" |
| #include "llvm/Support/PatternMatch.h" |
| using namespace llvm; |
| using namespace PatternMatch; |
| |
| /// AddOne - Add one to a ConstantInt. |
| static Constant *AddOne(Constant *C) { |
| return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1)); |
| } |
| /// SubOne - Subtract one from a ConstantInt. |
| static Constant *SubOne(ConstantInt *C) { |
| return ConstantInt::get(C->getContext(), C->getValue()-1); |
| } |
| |
| |
| // dyn_castFoldableMul - If this value is a multiply that can be folded into |
| // other computations (because it has a constant operand), return the |
| // non-constant operand of the multiply, and set CST to point to the multiplier. |
| // Otherwise, return null. |
| // |
| static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) { |
| if (!V->hasOneUse() || !V->getType()->isIntegerTy()) |
| return 0; |
| |
| Instruction *I = dyn_cast<Instruction>(V); |
| if (I == 0) return 0; |
| |
| if (I->getOpcode() == Instruction::Mul) |
| if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) |
| return I->getOperand(0); |
| if (I->getOpcode() == Instruction::Shl) |
| if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) { |
| // The multiplier is really 1 << CST. |
| uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth(); |
| uint32_t CSTVal = CST->getLimitedValue(BitWidth); |
| CST = ConstantInt::get(V->getType()->getContext(), |
| APInt(BitWidth, 1).shl(CSTVal)); |
| return I->getOperand(0); |
| } |
| return 0; |
| } |
| |
| |
| /// WillNotOverflowSignedAdd - Return true if we can prove that: |
| /// (sext (add LHS, RHS)) === (add (sext LHS), (sext RHS)) |
| /// This basically requires proving that the add in the original type would not |
| /// overflow to change the sign bit or have a carry out. |
| bool InstCombiner::WillNotOverflowSignedAdd(Value *LHS, Value *RHS) { |
| // There are different heuristics we can use for this. Here are some simple |
| // ones. |
| |
| // Add has the property that adding any two 2's complement numbers can only |
| // have one carry bit which can change a sign. As such, if LHS and RHS each |
| // have at least two sign bits, we know that the addition of the two values |
| // will sign extend fine. |
| if (ComputeNumSignBits(LHS) > 1 && ComputeNumSignBits(RHS) > 1) |
| return true; |
| |
| |
| // If one of the operands only has one non-zero bit, and if the other operand |
| // has a known-zero bit in a more significant place than it (not including the |
| // sign bit) the ripple may go up to and fill the zero, but won't change the |
| // sign. For example, (X & ~4) + 1. |
| |
| // TODO: Implement. |
| |
| return false; |
| } |
| |
| Instruction *InstCombiner::visitAdd(BinaryOperator &I) { |
| bool Changed = SimplifyCommutative(I); |
| Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); |
| |
| if (Value *V = SimplifyAddInst(LHS, RHS, I.hasNoSignedWrap(), |
| I.hasNoUnsignedWrap(), TD)) |
| return ReplaceInstUsesWith(I, V); |
| |
| |
| if (Constant *RHSC = dyn_cast<Constant>(RHS)) { |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) { |
| // X + (signbit) --> X ^ signbit |
| const APInt& Val = CI->getValue(); |
| uint32_t BitWidth = Val.getBitWidth(); |
| if (Val == APInt::getSignBit(BitWidth)) |
| return BinaryOperator::CreateXor(LHS, RHS); |
| |
| // See if SimplifyDemandedBits can simplify this. This handles stuff like |
| // (X & 254)+1 -> (X&254)|1 |
| if (SimplifyDemandedInstructionBits(I)) |
| return &I; |
| |
| // zext(bool) + C -> bool ? C + 1 : C |
| if (ZExtInst *ZI = dyn_cast<ZExtInst>(LHS)) |
| if (ZI->getSrcTy() == Type::getInt1Ty(I.getContext())) |
| return SelectInst::Create(ZI->getOperand(0), AddOne(CI), CI); |
| } |
| |
| if (isa<PHINode>(LHS)) |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| |
| ConstantInt *XorRHS = 0; |
| Value *XorLHS = 0; |
| if (isa<ConstantInt>(RHSC) && |
| match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) { |
| uint32_t TySizeBits = I.getType()->getScalarSizeInBits(); |
| const APInt& RHSVal = cast<ConstantInt>(RHSC)->getValue(); |
| unsigned ExtendAmt = 0; |
| // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext. |
| // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext. |
| if (XorRHS->getValue() == -RHSVal) { |
| if (RHSVal.isPowerOf2()) |
| ExtendAmt = TySizeBits - RHSVal.logBase2() - 1; |
| else if (XorRHS->getValue().isPowerOf2()) |
| ExtendAmt = TySizeBits - XorRHS->getValue().logBase2() - 1; |
| } |
| |
| if (ExtendAmt) { |
| APInt Mask = APInt::getHighBitsSet(TySizeBits, ExtendAmt); |
| if (!MaskedValueIsZero(XorLHS, Mask)) |
| ExtendAmt = 0; |
| } |
| |
| if (ExtendAmt) { |
| Constant *ShAmt = ConstantInt::get(I.getType(), ExtendAmt); |
| Value *NewShl = Builder->CreateShl(XorLHS, ShAmt, "sext"); |
| return BinaryOperator::CreateAShr(NewShl, ShAmt); |
| } |
| } |
| } |
| |
| if (I.getType()->isIntegerTy(1)) |
| return BinaryOperator::CreateXor(LHS, RHS); |
| |
| if (I.getType()->isIntegerTy()) { |
| // X + X --> X << 1 |
| if (LHS == RHS) |
| return BinaryOperator::CreateShl(LHS, ConstantInt::get(I.getType(), 1)); |
| |
| if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) { |
| if (RHSI->getOpcode() == Instruction::Sub) |
| if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B |
| return ReplaceInstUsesWith(I, RHSI->getOperand(0)); |
| } |
| if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) { |
| if (LHSI->getOpcode() == Instruction::Sub) |
| if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B |
| return ReplaceInstUsesWith(I, LHSI->getOperand(0)); |
| } |
| } |
| |
| // -A + B --> B - A |
| // -A + -B --> -(A + B) |
| if (Value *LHSV = dyn_castNegVal(LHS)) { |
| if (LHS->getType()->isIntOrIntVectorTy()) { |
| if (Value *RHSV = dyn_castNegVal(RHS)) { |
| Value *NewAdd = Builder->CreateAdd(LHSV, RHSV, "sum"); |
| return BinaryOperator::CreateNeg(NewAdd); |
| } |
| } |
| |
| return BinaryOperator::CreateSub(RHS, LHSV); |
| } |
| |
| // A + -B --> A - B |
| if (!isa<Constant>(RHS)) |
| if (Value *V = dyn_castNegVal(RHS)) |
| return BinaryOperator::CreateSub(LHS, V); |
| |
| |
| ConstantInt *C2; |
| if (Value *X = dyn_castFoldableMul(LHS, C2)) { |
| if (X == RHS) // X*C + X --> X * (C+1) |
| return BinaryOperator::CreateMul(RHS, AddOne(C2)); |
| |
| // X*C1 + X*C2 --> X * (C1+C2) |
| ConstantInt *C1; |
| if (X == dyn_castFoldableMul(RHS, C1)) |
| return BinaryOperator::CreateMul(X, ConstantExpr::getAdd(C1, C2)); |
| } |
| |
| // X + X*C --> X * (C+1) |
| if (dyn_castFoldableMul(RHS, C2) == LHS) |
| return BinaryOperator::CreateMul(LHS, AddOne(C2)); |
| |
| // X + ~X --> -1 since ~X = -X-1 |
| if (match(LHS, m_Not(m_Specific(RHS))) || |
| match(RHS, m_Not(m_Specific(LHS)))) |
| return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType())); |
| |
| // A+B --> A|B iff A and B have no bits set in common. |
| if (const IntegerType *IT = dyn_cast<IntegerType>(I.getType())) { |
| APInt Mask = APInt::getAllOnesValue(IT->getBitWidth()); |
| APInt LHSKnownOne(IT->getBitWidth(), 0); |
| APInt LHSKnownZero(IT->getBitWidth(), 0); |
| ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne); |
| if (LHSKnownZero != 0) { |
| APInt RHSKnownOne(IT->getBitWidth(), 0); |
| APInt RHSKnownZero(IT->getBitWidth(), 0); |
| ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne); |
| |
| // No bits in common -> bitwise or. |
| if ((LHSKnownZero|RHSKnownZero).isAllOnesValue()) |
| return BinaryOperator::CreateOr(LHS, RHS); |
| } |
| } |
| |
| // W*X + Y*Z --> W * (X+Z) iff W == Y |
| if (I.getType()->isIntOrIntVectorTy()) { |
| Value *W, *X, *Y, *Z; |
| if (match(LHS, m_Mul(m_Value(W), m_Value(X))) && |
| match(RHS, m_Mul(m_Value(Y), m_Value(Z)))) { |
| if (W != Y) { |
| if (W == Z) { |
| std::swap(Y, Z); |
| } else if (Y == X) { |
| std::swap(W, X); |
| } else if (X == Z) { |
| std::swap(Y, Z); |
| std::swap(W, X); |
| } |
| } |
| |
| if (W == Y) { |
| Value *NewAdd = Builder->CreateAdd(X, Z, LHS->getName()); |
| return BinaryOperator::CreateMul(W, NewAdd); |
| } |
| } |
| } |
| |
| if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) { |
| Value *X = 0; |
| if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X |
| return BinaryOperator::CreateSub(SubOne(CRHS), X); |
| |
| // (X & FF00) + xx00 -> (X+xx00) & FF00 |
| if (LHS->hasOneUse() && |
| match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) { |
| Constant *Anded = ConstantExpr::getAnd(CRHS, C2); |
| if (Anded == CRHS) { |
| // See if all bits from the first bit set in the Add RHS up are included |
| // in the mask. First, get the rightmost bit. |
| const APInt &AddRHSV = CRHS->getValue(); |
| |
| // Form a mask of all bits from the lowest bit added through the top. |
| APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1)); |
| |
| // See if the and mask includes all of these bits. |
| APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue()); |
| |
| if (AddRHSHighBits == AddRHSHighBitsAnd) { |
| // Okay, the xform is safe. Insert the new add pronto. |
| Value *NewAdd = Builder->CreateAdd(X, CRHS, LHS->getName()); |
| return BinaryOperator::CreateAnd(NewAdd, C2); |
| } |
| } |
| } |
| |
| // Try to fold constant add into select arguments. |
| if (SelectInst *SI = dyn_cast<SelectInst>(LHS)) |
| if (Instruction *R = FoldOpIntoSelect(I, SI)) |
| return R; |
| } |
| |
| // add (select X 0 (sub n A)) A --> select X A n |
| { |
| SelectInst *SI = dyn_cast<SelectInst>(LHS); |
| Value *A = RHS; |
| if (!SI) { |
| SI = dyn_cast<SelectInst>(RHS); |
| A = LHS; |
| } |
| if (SI && SI->hasOneUse()) { |
| Value *TV = SI->getTrueValue(); |
| Value *FV = SI->getFalseValue(); |
| Value *N; |
| |
| // Can we fold the add into the argument of the select? |
| // We check both true and false select arguments for a matching subtract. |
| if (match(FV, m_Zero()) && |
| match(TV, m_Sub(m_Value(N), m_Specific(A)))) |
| // Fold the add into the true select value. |
| return SelectInst::Create(SI->getCondition(), N, A); |
| if (match(TV, m_Zero()) && |
| match(FV, m_Sub(m_Value(N), m_Specific(A)))) |
| // Fold the add into the false select value. |
| return SelectInst::Create(SI->getCondition(), A, N); |
| } |
| } |
| |
| // Check for (add (sext x), y), see if we can merge this into an |
| // integer add followed by a sext. |
| if (SExtInst *LHSConv = dyn_cast<SExtInst>(LHS)) { |
| // (add (sext x), cst) --> (sext (add x, cst')) |
| if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) { |
| Constant *CI = |
| ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType()); |
| if (LHSConv->hasOneUse() && |
| ConstantExpr::getSExt(CI, I.getType()) == RHSC && |
| WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) { |
| // Insert the new, smaller add. |
| Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0), |
| CI, "addconv"); |
| return new SExtInst(NewAdd, I.getType()); |
| } |
| } |
| |
| // (add (sext x), (sext y)) --> (sext (add int x, y)) |
| if (SExtInst *RHSConv = dyn_cast<SExtInst>(RHS)) { |
| // Only do this if x/y have the same type, if at last one of them has a |
| // single use (so we don't increase the number of sexts), and if the |
| // integer add will not overflow. |
| if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&& |
| (LHSConv->hasOneUse() || RHSConv->hasOneUse()) && |
| WillNotOverflowSignedAdd(LHSConv->getOperand(0), |
| RHSConv->getOperand(0))) { |
| // Insert the new integer add. |
| Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0), |
| RHSConv->getOperand(0), "addconv"); |
| return new SExtInst(NewAdd, I.getType()); |
| } |
| } |
| } |
| |
| return Changed ? &I : 0; |
| } |
| |
| Instruction *InstCombiner::visitFAdd(BinaryOperator &I) { |
| bool Changed = SimplifyCommutative(I); |
| Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); |
| |
| if (Constant *RHSC = dyn_cast<Constant>(RHS)) { |
| // X + 0 --> X |
| if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) { |
| if (CFP->isExactlyValue(ConstantFP::getNegativeZero |
| (I.getType())->getValueAPF())) |
| return ReplaceInstUsesWith(I, LHS); |
| } |
| |
| if (isa<PHINode>(LHS)) |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| } |
| |
| // -A + B --> B - A |
| // -A + -B --> -(A + B) |
| if (Value *LHSV = dyn_castFNegVal(LHS)) |
| return BinaryOperator::CreateFSub(RHS, LHSV); |
| |
| // A + -B --> A - B |
| if (!isa<Constant>(RHS)) |
| if (Value *V = dyn_castFNegVal(RHS)) |
| return BinaryOperator::CreateFSub(LHS, V); |
| |
| // Check for X+0.0. Simplify it to X if we know X is not -0.0. |
| if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) |
| if (CFP->getValueAPF().isPosZero() && CannotBeNegativeZero(LHS)) |
| return ReplaceInstUsesWith(I, LHS); |
| |
| // Check for (fadd double (sitofp x), y), see if we can merge this into an |
| // integer add followed by a promotion. |
| if (SIToFPInst *LHSConv = dyn_cast<SIToFPInst>(LHS)) { |
| // (fadd double (sitofp x), fpcst) --> (sitofp (add int x, intcst)) |
| // ... if the constant fits in the integer value. This is useful for things |
| // like (double)(x & 1234) + 4.0 -> (double)((X & 1234)+4) which no longer |
| // requires a constant pool load, and generally allows the add to be better |
| // instcombined. |
| if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) { |
| Constant *CI = |
| ConstantExpr::getFPToSI(CFP, LHSConv->getOperand(0)->getType()); |
| if (LHSConv->hasOneUse() && |
| ConstantExpr::getSIToFP(CI, I.getType()) == CFP && |
| WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) { |
| // Insert the new integer add. |
| Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0), |
| CI, "addconv"); |
| return new SIToFPInst(NewAdd, I.getType()); |
| } |
| } |
| |
| // (fadd double (sitofp x), (sitofp y)) --> (sitofp (add int x, y)) |
| if (SIToFPInst *RHSConv = dyn_cast<SIToFPInst>(RHS)) { |
| // Only do this if x/y have the same type, if at last one of them has a |
| // single use (so we don't increase the number of int->fp conversions), |
| // and if the integer add will not overflow. |
| if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&& |
| (LHSConv->hasOneUse() || RHSConv->hasOneUse()) && |
| WillNotOverflowSignedAdd(LHSConv->getOperand(0), |
| RHSConv->getOperand(0))) { |
| // Insert the new integer add. |
| Value *NewAdd = Builder->CreateNSWAdd(LHSConv->getOperand(0), |
| RHSConv->getOperand(0),"addconv"); |
| return new SIToFPInst(NewAdd, I.getType()); |
| } |
| } |
| } |
| |
| return Changed ? &I : 0; |
| } |
| |
| |
| /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the |
| /// code necessary to compute the offset from the base pointer (without adding |
| /// in the base pointer). Return the result as a signed integer of intptr size. |
| Value *InstCombiner::EmitGEPOffset(User *GEP) { |
| TargetData &TD = *getTargetData(); |
| gep_type_iterator GTI = gep_type_begin(GEP); |
| const Type *IntPtrTy = TD.getIntPtrType(GEP->getContext()); |
| Value *Result = Constant::getNullValue(IntPtrTy); |
| |
| // Build a mask for high order bits. |
| unsigned IntPtrWidth = TD.getPointerSizeInBits(); |
| uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth); |
| |
| for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e; |
| ++i, ++GTI) { |
| Value *Op = *i; |
| uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()) & PtrSizeMask; |
| if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) { |
| if (OpC->isZero()) continue; |
| |
| // Handle a struct index, which adds its field offset to the pointer. |
| if (const StructType *STy = dyn_cast<StructType>(*GTI)) { |
| Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue()); |
| |
| Result = Builder->CreateAdd(Result, |
| ConstantInt::get(IntPtrTy, Size), |
| GEP->getName()+".offs"); |
| continue; |
| } |
| |
| Constant *Scale = ConstantInt::get(IntPtrTy, Size); |
| Constant *OC = |
| ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/); |
| Scale = ConstantExpr::getMul(OC, Scale); |
| // Emit an add instruction. |
| Result = Builder->CreateAdd(Result, Scale, GEP->getName()+".offs"); |
| continue; |
| } |
| // Convert to correct type. |
| if (Op->getType() != IntPtrTy) |
| Op = Builder->CreateIntCast(Op, IntPtrTy, true, Op->getName()+".c"); |
| if (Size != 1) { |
| Constant *Scale = ConstantInt::get(IntPtrTy, Size); |
| // We'll let instcombine(mul) convert this to a shl if possible. |
| Op = Builder->CreateMul(Op, Scale, GEP->getName()+".idx"); |
| } |
| |
| // Emit an add instruction. |
| Result = Builder->CreateAdd(Op, Result, GEP->getName()+".offs"); |
| } |
| return Result; |
| } |
| |
| |
| |
| |
| /// Optimize pointer differences into the same array into a size. Consider: |
| /// &A[10] - &A[0]: we should compile this to "10". LHS/RHS are the pointer |
| /// operands to the ptrtoint instructions for the LHS/RHS of the subtract. |
| /// |
| Value *InstCombiner::OptimizePointerDifference(Value *LHS, Value *RHS, |
| const Type *Ty) { |
| assert(TD && "Must have target data info for this"); |
| |
| // If LHS is a gep based on RHS or RHS is a gep based on LHS, we can optimize |
| // this. |
| bool Swapped = false; |
| GetElementPtrInst *GEP = 0; |
| ConstantExpr *CstGEP = 0; |
| |
| // TODO: Could also optimize &A[i] - &A[j] -> "i-j", and "&A.foo[i] - &A.foo". |
| // For now we require one side to be the base pointer "A" or a constant |
| // expression derived from it. |
| if (GetElementPtrInst *LHSGEP = dyn_cast<GetElementPtrInst>(LHS)) { |
| // (gep X, ...) - X |
| if (LHSGEP->getOperand(0) == RHS) { |
| GEP = LHSGEP; |
| Swapped = false; |
| } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(RHS)) { |
| // (gep X, ...) - (ce_gep X, ...) |
| if (CE->getOpcode() == Instruction::GetElementPtr && |
| LHSGEP->getOperand(0) == CE->getOperand(0)) { |
| CstGEP = CE; |
| GEP = LHSGEP; |
| Swapped = false; |
| } |
| } |
| } |
| |
| if (GetElementPtrInst *RHSGEP = dyn_cast<GetElementPtrInst>(RHS)) { |
| // X - (gep X, ...) |
| if (RHSGEP->getOperand(0) == LHS) { |
| GEP = RHSGEP; |
| Swapped = true; |
| } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(LHS)) { |
| // (ce_gep X, ...) - (gep X, ...) |
| if (CE->getOpcode() == Instruction::GetElementPtr && |
| RHSGEP->getOperand(0) == CE->getOperand(0)) { |
| CstGEP = CE; |
| GEP = RHSGEP; |
| Swapped = true; |
| } |
| } |
| } |
| |
| if (GEP == 0) |
| return 0; |
| |
| // Emit the offset of the GEP and an intptr_t. |
| Value *Result = EmitGEPOffset(GEP); |
| |
| // If we had a constant expression GEP on the other side offsetting the |
| // pointer, subtract it from the offset we have. |
| if (CstGEP) { |
| Value *CstOffset = EmitGEPOffset(CstGEP); |
| Result = Builder->CreateSub(Result, CstOffset); |
| } |
| |
| |
| // If we have p - gep(p, ...) then we have to negate the result. |
| if (Swapped) |
| Result = Builder->CreateNeg(Result, "diff.neg"); |
| |
| return Builder->CreateIntCast(Result, Ty, true); |
| } |
| |
| |
| Instruction *InstCombiner::visitSub(BinaryOperator &I) { |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| if (Op0 == Op1) // sub X, X -> 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| |
| // If this is a 'B = x-(-A)', change to B = x+A. This preserves NSW/NUW. |
| if (Value *V = dyn_castNegVal(Op1)) { |
| BinaryOperator *Res = BinaryOperator::CreateAdd(Op0, V); |
| Res->setHasNoSignedWrap(I.hasNoSignedWrap()); |
| Res->setHasNoUnsignedWrap(I.hasNoUnsignedWrap()); |
| return Res; |
| } |
| |
| if (isa<UndefValue>(Op0)) |
| return ReplaceInstUsesWith(I, Op0); // undef - X -> undef |
| if (isa<UndefValue>(Op1)) |
| return ReplaceInstUsesWith(I, Op1); // X - undef -> undef |
| if (I.getType()->isIntegerTy(1)) |
| return BinaryOperator::CreateXor(Op0, Op1); |
| |
| if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) { |
| // Replace (-1 - A) with (~A). |
| if (C->isAllOnesValue()) |
| return BinaryOperator::CreateNot(Op1); |
| |
| // C - ~X == X + (1+C) |
| Value *X = 0; |
| if (match(Op1, m_Not(m_Value(X)))) |
| return BinaryOperator::CreateAdd(X, AddOne(C)); |
| |
| // -(X >>u 31) -> (X >>s 31) |
| // -(X >>s 31) -> (X >>u 31) |
| if (C->isZero()) { |
| if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op1)) { |
| if (SI->getOpcode() == Instruction::LShr) { |
| if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) { |
| // Check to see if we are shifting out everything but the sign bit. |
| if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) == |
| SI->getType()->getPrimitiveSizeInBits()-1) { |
| // Ok, the transformation is safe. Insert AShr. |
| return BinaryOperator::Create(Instruction::AShr, |
| SI->getOperand(0), CU, SI->getName()); |
| } |
| } |
| } else if (SI->getOpcode() == Instruction::AShr) { |
| if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) { |
| // Check to see if we are shifting out everything but the sign bit. |
| if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) == |
| SI->getType()->getPrimitiveSizeInBits()-1) { |
| // Ok, the transformation is safe. Insert LShr. |
| return BinaryOperator::CreateLShr( |
| SI->getOperand(0), CU, SI->getName()); |
| } |
| } |
| } |
| } |
| } |
| |
| // Try to fold constant sub into select arguments. |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) |
| if (Instruction *R = FoldOpIntoSelect(I, SI)) |
| return R; |
| |
| // C - zext(bool) -> bool ? C - 1 : C |
| if (ZExtInst *ZI = dyn_cast<ZExtInst>(Op1)) |
| if (ZI->getSrcTy() == Type::getInt1Ty(I.getContext())) |
| return SelectInst::Create(ZI->getOperand(0), SubOne(C), C); |
| } |
| |
| if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) { |
| if (Op1I->getOpcode() == Instruction::Add) { |
| if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y |
| return BinaryOperator::CreateNeg(Op1I->getOperand(1), |
| I.getName()); |
| else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y |
| return BinaryOperator::CreateNeg(Op1I->getOperand(0), |
| I.getName()); |
| else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) { |
| if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1))) |
| // C1-(X+C2) --> (C1-C2)-X |
| return BinaryOperator::CreateSub( |
| ConstantExpr::getSub(CI1, CI2), Op1I->getOperand(0)); |
| } |
| } |
| |
| if (Op1I->hasOneUse()) { |
| // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression |
| // is not used by anyone else... |
| // |
| if (Op1I->getOpcode() == Instruction::Sub) { |
| // Swap the two operands of the subexpr... |
| Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1); |
| Op1I->setOperand(0, IIOp1); |
| Op1I->setOperand(1, IIOp0); |
| |
| // Create the new top level add instruction... |
| return BinaryOperator::CreateAdd(Op0, Op1); |
| } |
| |
| // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)... |
| // |
| if (Op1I->getOpcode() == Instruction::And && |
| (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) { |
| Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0); |
| |
| Value *NewNot = Builder->CreateNot(OtherOp, "B.not"); |
| return BinaryOperator::CreateAnd(Op0, NewNot); |
| } |
| |
| // 0 - (X sdiv C) -> (X sdiv -C) |
| if (Op1I->getOpcode() == Instruction::SDiv) |
| if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0)) |
| if (CSI->isZero()) |
| if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1))) |
| return BinaryOperator::CreateSDiv(Op1I->getOperand(0), |
| ConstantExpr::getNeg(DivRHS)); |
| |
| // 0 - (C << X) -> (-C << X) |
| if (Op1I->getOpcode() == Instruction::Shl) |
| if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0)) |
| if (CSI->isZero()) |
| if (Value *ShlLHSNeg = dyn_castNegVal(Op1I->getOperand(0))) |
| return BinaryOperator::CreateShl(ShlLHSNeg, Op1I->getOperand(1)); |
| |
| // X - X*C --> X * (1-C) |
| ConstantInt *C2 = 0; |
| if (dyn_castFoldableMul(Op1I, C2) == Op0) { |
| Constant *CP1 = |
| ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), |
| C2); |
| return BinaryOperator::CreateMul(Op0, CP1); |
| } |
| } |
| } |
| |
| if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) { |
| if (Op0I->getOpcode() == Instruction::Add) { |
| if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X |
| return ReplaceInstUsesWith(I, Op0I->getOperand(1)); |
| else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X |
| return ReplaceInstUsesWith(I, Op0I->getOperand(0)); |
| } else if (Op0I->getOpcode() == Instruction::Sub) { |
| if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y |
| return BinaryOperator::CreateNeg(Op0I->getOperand(1), |
| I.getName()); |
| } |
| } |
| |
| ConstantInt *C1; |
| if (Value *X = dyn_castFoldableMul(Op0, C1)) { |
| if (X == Op1) // X*C - X --> X * (C-1) |
| return BinaryOperator::CreateMul(Op1, SubOne(C1)); |
| |
| ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2) |
| if (X == dyn_castFoldableMul(Op1, C2)) |
| return BinaryOperator::CreateMul(X, ConstantExpr::getSub(C1, C2)); |
| } |
| |
| // Optimize pointer differences into the same array into a size. Consider: |
| // &A[10] - &A[0]: we should compile this to "10". |
| if (TD) { |
| Value *LHSOp, *RHSOp; |
| if (match(Op0, m_PtrToInt(m_Value(LHSOp))) && |
| match(Op1, m_PtrToInt(m_Value(RHSOp)))) |
| if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType())) |
| return ReplaceInstUsesWith(I, Res); |
| |
| // trunc(p)-trunc(q) -> trunc(p-q) |
| if (match(Op0, m_Trunc(m_PtrToInt(m_Value(LHSOp)))) && |
| match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp))))) |
| if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType())) |
| return ReplaceInstUsesWith(I, Res); |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitFSub(BinaryOperator &I) { |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| // If this is a 'B = x-(-A)', change to B = x+A... |
| if (Value *V = dyn_castFNegVal(Op1)) |
| return BinaryOperator::CreateFAdd(Op0, V); |
| |
| return 0; |
| } |
