| //===- InstCombineCasts.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 cast operations. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "InstCombine.h" |
| #include "llvm/Target/TargetData.h" |
| #include "llvm/Support/PatternMatch.h" |
| using namespace llvm; |
| using namespace PatternMatch; |
| |
| /// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear |
| /// expression. If so, decompose it, returning some value X, such that Val is |
| /// X*Scale+Offset. |
| /// |
| static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale, |
| int &Offset) { |
| assert(Val->getType()->isInteger(32) && "Unexpected allocation size type!"); |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) { |
| Offset = CI->getZExtValue(); |
| Scale = 0; |
| return ConstantInt::get(Type::getInt32Ty(Val->getContext()), 0); |
| } |
| |
| if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) { |
| if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| if (I->getOpcode() == Instruction::Shl) { |
| // This is a value scaled by '1 << the shift amt'. |
| Scale = 1U << RHS->getZExtValue(); |
| Offset = 0; |
| return I->getOperand(0); |
| } |
| |
| if (I->getOpcode() == Instruction::Mul) { |
| // This value is scaled by 'RHS'. |
| Scale = RHS->getZExtValue(); |
| Offset = 0; |
| return I->getOperand(0); |
| } |
| |
| if (I->getOpcode() == Instruction::Add) { |
| // We have X+C. Check to see if we really have (X*C2)+C1, |
| // where C1 is divisible by C2. |
| unsigned SubScale; |
| Value *SubVal = |
| DecomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset); |
| Offset += RHS->getZExtValue(); |
| Scale = SubScale; |
| return SubVal; |
| } |
| } |
| } |
| |
| // Otherwise, we can't look past this. |
| Scale = 1; |
| Offset = 0; |
| return Val; |
| } |
| |
| /// PromoteCastOfAllocation - If we find a cast of an allocation instruction, |
| /// try to eliminate the cast by moving the type information into the alloc. |
| Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI, |
| AllocaInst &AI) { |
| // This requires TargetData to get the alloca alignment and size information. |
| if (!TD) return 0; |
| |
| const PointerType *PTy = cast<PointerType>(CI.getType()); |
| |
| BuilderTy AllocaBuilder(*Builder); |
| AllocaBuilder.SetInsertPoint(AI.getParent(), &AI); |
| |
| // Get the type really allocated and the type casted to. |
| const Type *AllocElTy = AI.getAllocatedType(); |
| const Type *CastElTy = PTy->getElementType(); |
| if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0; |
| |
| unsigned AllocElTyAlign = TD->getABITypeAlignment(AllocElTy); |
| unsigned CastElTyAlign = TD->getABITypeAlignment(CastElTy); |
| if (CastElTyAlign < AllocElTyAlign) return 0; |
| |
| // If the allocation has multiple uses, only promote it if we are strictly |
| // increasing the alignment of the resultant allocation. If we keep it the |
| // same, we open the door to infinite loops of various kinds. (A reference |
| // from a dbg.declare doesn't count as a use for this purpose.) |
| if (!AI.hasOneUse() && !hasOneUsePlusDeclare(&AI) && |
| CastElTyAlign == AllocElTyAlign) return 0; |
| |
| uint64_t AllocElTySize = TD->getTypeAllocSize(AllocElTy); |
| uint64_t CastElTySize = TD->getTypeAllocSize(CastElTy); |
| if (CastElTySize == 0 || AllocElTySize == 0) return 0; |
| |
| // See if we can satisfy the modulus by pulling a scale out of the array |
| // size argument. |
| unsigned ArraySizeScale; |
| int ArrayOffset; |
| Value *NumElements = // See if the array size is a decomposable linear expr. |
| DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset); |
| |
| // If we can now satisfy the modulus, by using a non-1 scale, we really can |
| // do the xform. |
| if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 || |
| (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0; |
| |
| unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize; |
| Value *Amt = 0; |
| if (Scale == 1) { |
| Amt = NumElements; |
| } else { |
| Amt = ConstantInt::get(Type::getInt32Ty(CI.getContext()), Scale); |
| // Insert before the alloca, not before the cast. |
| Amt = AllocaBuilder.CreateMul(Amt, NumElements, "tmp"); |
| } |
| |
| if (int Offset = (AllocElTySize*ArrayOffset)/CastElTySize) { |
| Value *Off = ConstantInt::get(Type::getInt32Ty(CI.getContext()), |
| Offset, true); |
| Amt = AllocaBuilder.CreateAdd(Amt, Off, "tmp"); |
| } |
| |
| AllocaInst *New = AllocaBuilder.CreateAlloca(CastElTy, Amt); |
| New->setAlignment(AI.getAlignment()); |
| New->takeName(&AI); |
| |
| // If the allocation has one real use plus a dbg.declare, just remove the |
| // declare. |
| if (DbgDeclareInst *DI = hasOneUsePlusDeclare(&AI)) { |
| EraseInstFromFunction(*(Instruction*)DI); |
| } |
| // If the allocation has multiple real uses, insert a cast and change all |
| // things that used it to use the new cast. This will also hack on CI, but it |
| // will die soon. |
| else if (!AI.hasOneUse()) { |
| // New is the allocation instruction, pointer typed. AI is the original |
| // allocation instruction, also pointer typed. Thus, cast to use is BitCast. |
| Value *NewCast = AllocaBuilder.CreateBitCast(New, AI.getType(), "tmpcast"); |
| AI.replaceAllUsesWith(NewCast); |
| } |
| return ReplaceInstUsesWith(CI, New); |
| } |
| |
| |
| /// CanEvaluateInDifferentType - Return true if we can take the specified value |
| /// and return it as type Ty without inserting any new casts and without |
| /// changing the computed value. This is used by code that tries to decide |
| /// whether promoting or shrinking integer operations to wider or smaller types |
| /// will allow us to eliminate a truncate or extend. |
| /// |
| /// This is a truncation operation if Ty is smaller than V->getType(), or an |
| /// extension operation if Ty is larger. |
| /// |
| /// If CastOpc is a truncation, then Ty will be a type smaller than V. We |
| /// should return true if trunc(V) can be computed by computing V in the smaller |
| /// type. If V is an instruction, then trunc(inst(x,y)) can be computed as |
| /// inst(trunc(x),trunc(y)), which only makes sense if x and y can be |
| /// efficiently truncated. |
| /// |
| /// If CastOpc is a sext or zext, we are asking if the low bits of the value can |
| /// bit computed in a larger type, which is then and'd or sext_in_reg'd to get |
| /// the final result. |
| bool InstCombiner::CanEvaluateInDifferentType(Value *V, const Type *Ty, |
| unsigned CastOpc, |
| int &NumCastsRemoved){ |
| // We can always evaluate constants in another type. |
| if (isa<Constant>(V)) |
| return true; |
| |
| Instruction *I = dyn_cast<Instruction>(V); |
| if (!I) return false; |
| |
| const Type *OrigTy = V->getType(); |
| |
| // If this is an extension or truncate, we can often eliminate it. |
| if (isa<TruncInst>(I) || isa<ZExtInst>(I) || isa<SExtInst>(I)) { |
| // If this is a cast from the destination type, we can trivially eliminate |
| // it, and this will remove a cast overall. |
| if (I->getOperand(0)->getType() == Ty) { |
| // If the first operand is itself a cast, and is eliminable, do not count |
| // this as an eliminable cast. We would prefer to eliminate those two |
| // casts first. |
| if (!isa<CastInst>(I->getOperand(0)) && I->hasOneUse()) |
| ++NumCastsRemoved; |
| return true; |
| } |
| } |
| |
| // We can't extend or shrink something that has multiple uses: doing so would |
| // require duplicating the instruction in general, which isn't profitable. |
| if (!I->hasOneUse()) return false; |
| |
| unsigned Opc = I->getOpcode(); |
| switch (Opc) { |
| case Instruction::Add: |
| case Instruction::Sub: |
| case Instruction::Mul: |
| case Instruction::And: |
| case Instruction::Or: |
| case Instruction::Xor: |
| // These operators can all arbitrarily be extended or truncated. |
| return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc, |
| NumCastsRemoved) && |
| CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc, |
| NumCastsRemoved); |
| |
| case Instruction::UDiv: |
| case Instruction::URem: { |
| // UDiv and URem can be truncated if all the truncated bits are zero. |
| uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits(); |
| uint32_t BitWidth = Ty->getScalarSizeInBits(); |
| if (BitWidth < OrigBitWidth) { |
| APInt Mask = APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth); |
| if (MaskedValueIsZero(I->getOperand(0), Mask) && |
| MaskedValueIsZero(I->getOperand(1), Mask)) { |
| return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc, |
| NumCastsRemoved) && |
| CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc, |
| NumCastsRemoved); |
| } |
| } |
| break; |
| } |
| case Instruction::Shl: |
| // If we are truncating the result of this SHL, and if it's a shift of a |
| // constant amount, we can always perform a SHL in a smaller type. |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| uint32_t BitWidth = Ty->getScalarSizeInBits(); |
| if (BitWidth < OrigTy->getScalarSizeInBits() && |
| CI->getLimitedValue(BitWidth) < BitWidth) |
| return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc, |
| NumCastsRemoved); |
| } |
| break; |
| case Instruction::LShr: |
| // If this is a truncate of a logical shr, we can truncate it to a smaller |
| // lshr iff we know that the bits we would otherwise be shifting in are |
| // already zeros. |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits(); |
| uint32_t BitWidth = Ty->getScalarSizeInBits(); |
| if (BitWidth < OrigBitWidth && |
| MaskedValueIsZero(I->getOperand(0), |
| APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) && |
| CI->getLimitedValue(BitWidth) < BitWidth) { |
| return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc, |
| NumCastsRemoved); |
| } |
| } |
| break; |
| case Instruction::ZExt: |
| case Instruction::SExt: |
| case Instruction::Trunc: |
| // If this is the same kind of case as our original (e.g. zext+zext), we |
| // can safely replace it. Note that replacing it does not reduce the number |
| // of casts in the input. |
| if (Opc == CastOpc) |
| return true; |
| |
| // sext (zext ty1), ty2 -> zext ty2 |
| if (CastOpc == Instruction::SExt && Opc == Instruction::ZExt) |
| return true; |
| break; |
| case Instruction::Select: { |
| SelectInst *SI = cast<SelectInst>(I); |
| return CanEvaluateInDifferentType(SI->getTrueValue(), Ty, CastOpc, |
| NumCastsRemoved) && |
| CanEvaluateInDifferentType(SI->getFalseValue(), Ty, CastOpc, |
| NumCastsRemoved); |
| } |
| case Instruction::PHI: { |
| // We can change a phi if we can change all operands. |
| PHINode *PN = cast<PHINode>(I); |
| for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) |
| if (!CanEvaluateInDifferentType(PN->getIncomingValue(i), Ty, CastOpc, |
| NumCastsRemoved)) |
| return false; |
| return true; |
| } |
| default: |
| // TODO: Can handle more cases here. |
| break; |
| } |
| |
| return false; |
| } |
| |
| /// EvaluateInDifferentType - Given an expression that |
| /// CanEvaluateInDifferentType returns true for, actually insert the code to |
| /// evaluate the expression. |
| Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty, |
| bool isSigned) { |
| if (Constant *C = dyn_cast<Constant>(V)) |
| return ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/); |
| |
| // Otherwise, it must be an instruction. |
| Instruction *I = cast<Instruction>(V); |
| Instruction *Res = 0; |
| unsigned Opc = I->getOpcode(); |
| switch (Opc) { |
| case Instruction::Add: |
| case Instruction::Sub: |
| case Instruction::Mul: |
| case Instruction::And: |
| case Instruction::Or: |
| case Instruction::Xor: |
| case Instruction::AShr: |
| case Instruction::LShr: |
| case Instruction::Shl: |
| case Instruction::UDiv: |
| case Instruction::URem: { |
| Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned); |
| Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned); |
| Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS); |
| break; |
| } |
| case Instruction::Trunc: |
| case Instruction::ZExt: |
| case Instruction::SExt: |
| // If the source type of the cast is the type we're trying for then we can |
| // just return the source. There's no need to insert it because it is not |
| // new. |
| if (I->getOperand(0)->getType() == Ty) |
| return I->getOperand(0); |
| |
| // Otherwise, must be the same type of cast, so just reinsert a new one. |
| Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),Ty); |
| break; |
| case Instruction::Select: { |
| Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned); |
| Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned); |
| Res = SelectInst::Create(I->getOperand(0), True, False); |
| break; |
| } |
| case Instruction::PHI: { |
| PHINode *OPN = cast<PHINode>(I); |
| PHINode *NPN = PHINode::Create(Ty); |
| for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) { |
| Value *V =EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned); |
| NPN->addIncoming(V, OPN->getIncomingBlock(i)); |
| } |
| Res = NPN; |
| break; |
| } |
| default: |
| // TODO: Can handle more cases here. |
| llvm_unreachable("Unreachable!"); |
| break; |
| } |
| |
| Res->takeName(I); |
| return InsertNewInstBefore(Res, *I); |
| } |
| |
| |
| /// This function is a wrapper around CastInst::isEliminableCastPair. It |
| /// simply extracts arguments and returns what that function returns. |
| static Instruction::CastOps |
| isEliminableCastPair( |
| const CastInst *CI, ///< The first cast instruction |
| unsigned opcode, ///< The opcode of the second cast instruction |
| const Type *DstTy, ///< The target type for the second cast instruction |
| TargetData *TD ///< The target data for pointer size |
| ) { |
| |
| const Type *SrcTy = CI->getOperand(0)->getType(); // A from above |
| const Type *MidTy = CI->getType(); // B from above |
| |
| // Get the opcodes of the two Cast instructions |
| Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode()); |
| Instruction::CastOps secondOp = Instruction::CastOps(opcode); |
| |
| unsigned Res = CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, |
| DstTy, |
| TD ? TD->getIntPtrType(CI->getContext()) : 0); |
| |
| // We don't want to form an inttoptr or ptrtoint that converts to an integer |
| // type that differs from the pointer size. |
| if ((Res == Instruction::IntToPtr && |
| (!TD || SrcTy != TD->getIntPtrType(CI->getContext()))) || |
| (Res == Instruction::PtrToInt && |
| (!TD || DstTy != TD->getIntPtrType(CI->getContext())))) |
| Res = 0; |
| |
| return Instruction::CastOps(Res); |
| } |
| |
| /// ValueRequiresCast - Return true if the cast from "V to Ty" actually results |
| /// in any code being generated. It does not require codegen if V is simple |
| /// enough or if the cast can be folded into other casts. |
| bool InstCombiner::ValueRequiresCast(Instruction::CastOps opcode,const Value *V, |
| const Type *Ty) { |
| if (V->getType() == Ty || isa<Constant>(V)) return false; |
| |
| // If this is another cast that can be eliminated, it isn't codegen either. |
| if (const CastInst *CI = dyn_cast<CastInst>(V)) |
| if (isEliminableCastPair(CI, opcode, Ty, TD)) |
| return false; |
| return true; |
| } |
| |
| |
| /// @brief Implement the transforms common to all CastInst visitors. |
| Instruction *InstCombiner::commonCastTransforms(CastInst &CI) { |
| Value *Src = CI.getOperand(0); |
| |
| // Many cases of "cast of a cast" are eliminable. If it's eliminable we just |
| // eliminate it now. |
| if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast |
| if (Instruction::CastOps opc = |
| isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), TD)) { |
| // The first cast (CSrc) is eliminable so we need to fix up or replace |
| // the second cast (CI). CSrc will then have a good chance of being dead. |
| return CastInst::Create(opc, CSrc->getOperand(0), CI.getType()); |
| } |
| } |
| |
| // If we are casting a select then fold the cast into the select |
| if (SelectInst *SI = dyn_cast<SelectInst>(Src)) |
| if (Instruction *NV = FoldOpIntoSelect(CI, SI)) |
| return NV; |
| |
| // If we are casting a PHI then fold the cast into the PHI |
| if (isa<PHINode>(Src)) { |
| // We don't do this if this would create a PHI node with an illegal type if |
| // it is currently legal. |
| if (!isa<IntegerType>(Src->getType()) || |
| !isa<IntegerType>(CI.getType()) || |
| ShouldChangeType(CI.getType(), Src->getType())) |
| if (Instruction *NV = FoldOpIntoPhi(CI)) |
| return NV; |
| } |
| |
| return 0; |
| } |
| |
| /// @brief Implement the transforms for cast of pointer (bitcast/ptrtoint) |
| Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) { |
| Value *Src = CI.getOperand(0); |
| |
| if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) { |
| // If casting the result of a getelementptr instruction with no offset, turn |
| // this into a cast of the original pointer! |
| if (GEP->hasAllZeroIndices()) { |
| // Changing the cast operand is usually not a good idea but it is safe |
| // here because the pointer operand is being replaced with another |
| // pointer operand so the opcode doesn't need to change. |
| Worklist.Add(GEP); |
| CI.setOperand(0, GEP->getOperand(0)); |
| return &CI; |
| } |
| |
| // If the GEP has a single use, and the base pointer is a bitcast, and the |
| // GEP computes a constant offset, see if we can convert these three |
| // instructions into fewer. This typically happens with unions and other |
| // non-type-safe code. |
| if (TD && GEP->hasOneUse() && isa<BitCastInst>(GEP->getOperand(0))) { |
| if (GEP->hasAllConstantIndices()) { |
| // We are guaranteed to get a constant from EmitGEPOffset. |
| ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(GEP)); |
| int64_t Offset = OffsetV->getSExtValue(); |
| |
| // Get the base pointer input of the bitcast, and the type it points to. |
| Value *OrigBase = cast<BitCastInst>(GEP->getOperand(0))->getOperand(0); |
| const Type *GEPIdxTy = |
| cast<PointerType>(OrigBase->getType())->getElementType(); |
| SmallVector<Value*, 8> NewIndices; |
| if (FindElementAtOffset(GEPIdxTy, Offset, NewIndices)) { |
| // If we were able to index down into an element, create the GEP |
| // and bitcast the result. This eliminates one bitcast, potentially |
| // two. |
| Value *NGEP = cast<GEPOperator>(GEP)->isInBounds() ? |
| Builder->CreateInBoundsGEP(OrigBase, |
| NewIndices.begin(), NewIndices.end()) : |
| Builder->CreateGEP(OrigBase, NewIndices.begin(), NewIndices.end()); |
| NGEP->takeName(GEP); |
| |
| if (isa<BitCastInst>(CI)) |
| return new BitCastInst(NGEP, CI.getType()); |
| assert(isa<PtrToIntInst>(CI)); |
| return new PtrToIntInst(NGEP, CI.getType()); |
| } |
| } |
| } |
| } |
| |
| return commonCastTransforms(CI); |
| } |
| |
| /// commonIntCastTransforms - This function implements the common transforms |
| /// for trunc, zext, and sext. |
| Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) { |
| if (Instruction *Result = commonCastTransforms(CI)) |
| return Result; |
| |
| // See if we can simplify any instructions used by the LHS whose sole |
| // purpose is to compute bits we don't care about. |
| if (SimplifyDemandedInstructionBits(CI)) |
| return &CI; |
| |
| // If the source isn't an instruction or has more than one use then we |
| // can't do anything more. |
| Instruction *Src = dyn_cast<Instruction>(CI.getOperand(0)); |
| if (!Src || !Src->hasOneUse()) |
| return 0; |
| |
| const Type *SrcTy = Src->getType(); |
| const Type *DestTy = CI.getType(); |
| uint32_t SrcBitSize = SrcTy->getScalarSizeInBits(); |
| uint32_t DestBitSize = DestTy->getScalarSizeInBits(); |
| |
| // Attempt to propagate the cast into the instruction for int->int casts. |
| int NumCastsRemoved = 0; |
| // Only do this if the dest type is a simple type, don't convert the |
| // expression tree to something weird like i93 unless the source is also |
| // strange. |
| if ((isa<VectorType>(DestTy) || |
| ShouldChangeType(Src->getType(), DestTy)) && |
| CanEvaluateInDifferentType(Src, DestTy, |
| CI.getOpcode(), NumCastsRemoved)) { |
| // If this cast is a truncate, evaluting in a different type always |
| // eliminates the cast, so it is always a win. If this is a zero-extension, |
| // we need to do an AND to maintain the clear top-part of the computation, |
| // so we require that the input have eliminated at least one cast. If this |
| // is a sign extension, we insert two new casts (to do the extension) so we |
| // require that two casts have been eliminated. |
| bool DoXForm = false; |
| bool JustReplace = false; |
| switch (CI.getOpcode()) { |
| default: |
| // All the others use floating point so we shouldn't actually |
| // get here because of the check above. |
| llvm_unreachable("Unknown cast type"); |
| case Instruction::Trunc: |
| DoXForm = true; |
| break; |
| case Instruction::ZExt: { |
| DoXForm = NumCastsRemoved >= 1; |
| |
| if (!DoXForm && 0) { |
| // If it's unnecessary to issue an AND to clear the high bits, it's |
| // always profitable to do this xform. |
| Value *TryRes = EvaluateInDifferentType(Src, DestTy, false); |
| APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize)); |
| if (MaskedValueIsZero(TryRes, Mask)) |
| return ReplaceInstUsesWith(CI, TryRes); |
| |
| if (Instruction *TryI = dyn_cast<Instruction>(TryRes)) |
| if (TryI->use_empty()) |
| EraseInstFromFunction(*TryI); |
| } |
| break; |
| } |
| case Instruction::SExt: { |
| DoXForm = NumCastsRemoved >= 2; |
| if (!DoXForm && !isa<TruncInst>(Src) && 0) { |
| // If we do not have to emit the truncate + sext pair, then it's always |
| // profitable to do this xform. |
| // |
| // It's not safe to eliminate the trunc + sext pair if one of the |
| // eliminated cast is a truncate. e.g. |
| // t2 = trunc i32 t1 to i16 |
| // t3 = sext i16 t2 to i32 |
| // != |
| // i32 t1 |
| Value *TryRes = EvaluateInDifferentType(Src, DestTy, true); |
| unsigned NumSignBits = ComputeNumSignBits(TryRes); |
| if (NumSignBits > (DestBitSize - SrcBitSize)) |
| return ReplaceInstUsesWith(CI, TryRes); |
| |
| if (Instruction *TryI = dyn_cast<Instruction>(TryRes)) |
| if (TryI->use_empty()) |
| EraseInstFromFunction(*TryI); |
| } |
| break; |
| } |
| } |
| |
| if (DoXForm) { |
| DEBUG(errs() << "ICE: EvaluateInDifferentType converting expression type" |
| " to avoid cast: " << CI); |
| Value *Res = EvaluateInDifferentType(Src, DestTy, |
| CI.getOpcode() == Instruction::SExt); |
| if (JustReplace) |
| // Just replace this cast with the result. |
| return ReplaceInstUsesWith(CI, Res); |
| |
| assert(Res->getType() == DestTy); |
| switch (CI.getOpcode()) { |
| default: llvm_unreachable("Unknown cast type!"); |
| case Instruction::Trunc: |
| // Just replace this cast with the result. |
| return ReplaceInstUsesWith(CI, Res); |
| case Instruction::ZExt: { |
| assert(SrcBitSize < DestBitSize && "Not a zext?"); |
| |
| // If the high bits are already zero, just replace this cast with the |
| // result. |
| APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize)); |
| if (MaskedValueIsZero(Res, Mask)) |
| return ReplaceInstUsesWith(CI, Res); |
| |
| // We need to emit an AND to clear the high bits. |
| Constant *C = ConstantInt::get(CI.getContext(), |
| APInt::getLowBitsSet(DestBitSize, SrcBitSize)); |
| return BinaryOperator::CreateAnd(Res, C); |
| } |
| case Instruction::SExt: { |
| // If the high bits are already filled with sign bit, just replace this |
| // cast with the result. |
| unsigned NumSignBits = ComputeNumSignBits(Res); |
| if (NumSignBits > (DestBitSize - SrcBitSize)) |
| return ReplaceInstUsesWith(CI, Res); |
| |
| // We need to emit a cast to truncate, then a cast to sext. |
| return new SExtInst(Builder->CreateTrunc(Res, Src->getType()), DestTy); |
| } |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitTrunc(TruncInst &CI) { |
| if (Instruction *Result = commonIntCastTransforms(CI)) |
| return Result; |
| |
| Value *Src = CI.getOperand(0); |
| const Type *DestTy = CI.getType(); |
| |
| // Canonicalize trunc x to i1 -> (icmp ne (and x, 1), 0) |
| if (DestTy->isInteger(1)) { |
| Constant *One = ConstantInt::get(Src->getType(), 1); |
| Src = Builder->CreateAnd(Src, One, "tmp"); |
| Value *Zero = Constant::getNullValue(Src->getType()); |
| return new ICmpInst(ICmpInst::ICMP_NE, Src, Zero); |
| } |
| |
| return 0; |
| } |
| |
| /// transformZExtICmp - Transform (zext icmp) to bitwise / integer operations |
| /// in order to eliminate the icmp. |
| Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, Instruction &CI, |
| bool DoXform) { |
| // If we are just checking for a icmp eq of a single bit and zext'ing it |
| // to an integer, then shift the bit to the appropriate place and then |
| // cast to integer to avoid the comparison. |
| if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) { |
| const APInt &Op1CV = Op1C->getValue(); |
| |
| // zext (x <s 0) to i32 --> x>>u31 true if signbit set. |
| // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear. |
| if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) || |
| (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())) { |
| if (!DoXform) return ICI; |
| |
| Value *In = ICI->getOperand(0); |
| Value *Sh = ConstantInt::get(In->getType(), |
| In->getType()->getScalarSizeInBits()-1); |
| In = Builder->CreateLShr(In, Sh, In->getName()+".lobit"); |
| if (In->getType() != CI.getType()) |
| In = Builder->CreateIntCast(In, CI.getType(), false/*ZExt*/, "tmp"); |
| |
| if (ICI->getPredicate() == ICmpInst::ICMP_SGT) { |
| Constant *One = ConstantInt::get(In->getType(), 1); |
| In = Builder->CreateXor(In, One, In->getName()+".not"); |
| } |
| |
| return ReplaceInstUsesWith(CI, In); |
| } |
| |
| |
| |
| // zext (X == 0) to i32 --> X^1 iff X has only the low bit set. |
| // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set. |
| // zext (X == 1) to i32 --> X iff X has only the low bit set. |
| // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set. |
| // zext (X != 0) to i32 --> X iff X has only the low bit set. |
| // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set. |
| // zext (X != 1) to i32 --> X^1 iff X has only the low bit set. |
| // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set. |
| if ((Op1CV == 0 || Op1CV.isPowerOf2()) && |
| // This only works for EQ and NE |
| ICI->isEquality()) { |
| // If Op1C some other power of two, convert: |
| uint32_t BitWidth = Op1C->getType()->getBitWidth(); |
| APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); |
| APInt TypeMask(APInt::getAllOnesValue(BitWidth)); |
| ComputeMaskedBits(ICI->getOperand(0), TypeMask, KnownZero, KnownOne); |
| |
| APInt KnownZeroMask(~KnownZero); |
| if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1? |
| if (!DoXform) return ICI; |
| |
| bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE; |
| if (Op1CV != 0 && (Op1CV != KnownZeroMask)) { |
| // (X&4) == 2 --> false |
| // (X&4) != 2 --> true |
| Constant *Res = ConstantInt::get(Type::getInt1Ty(CI.getContext()), |
| isNE); |
| Res = ConstantExpr::getZExt(Res, CI.getType()); |
| return ReplaceInstUsesWith(CI, Res); |
| } |
| |
| uint32_t ShiftAmt = KnownZeroMask.logBase2(); |
| Value *In = ICI->getOperand(0); |
| if (ShiftAmt) { |
| // Perform a logical shr by shiftamt. |
| // Insert the shift to put the result in the low bit. |
| In = Builder->CreateLShr(In, ConstantInt::get(In->getType(),ShiftAmt), |
| In->getName()+".lobit"); |
| } |
| |
| if ((Op1CV != 0) == isNE) { // Toggle the low bit. |
| Constant *One = ConstantInt::get(In->getType(), 1); |
| In = Builder->CreateXor(In, One, "tmp"); |
| } |
| |
| if (CI.getType() == In->getType()) |
| return ReplaceInstUsesWith(CI, In); |
| else |
| return CastInst::CreateIntegerCast(In, CI.getType(), false/*ZExt*/); |
| } |
| } |
| } |
| |
| // icmp ne A, B is equal to xor A, B when A and B only really have one bit. |
| // It is also profitable to transform icmp eq into not(xor(A, B)) because that |
| // may lead to additional simplifications. |
| if (ICI->isEquality() && CI.getType() == ICI->getOperand(0)->getType()) { |
| if (const IntegerType *ITy = dyn_cast<IntegerType>(CI.getType())) { |
| uint32_t BitWidth = ITy->getBitWidth(); |
| Value *LHS = ICI->getOperand(0); |
| Value *RHS = ICI->getOperand(1); |
| |
| APInt KnownZeroLHS(BitWidth, 0), KnownOneLHS(BitWidth, 0); |
| APInt KnownZeroRHS(BitWidth, 0), KnownOneRHS(BitWidth, 0); |
| APInt TypeMask(APInt::getAllOnesValue(BitWidth)); |
| ComputeMaskedBits(LHS, TypeMask, KnownZeroLHS, KnownOneLHS); |
| ComputeMaskedBits(RHS, TypeMask, KnownZeroRHS, KnownOneRHS); |
| |
| if (KnownZeroLHS == KnownZeroRHS && KnownOneLHS == KnownOneRHS) { |
| APInt KnownBits = KnownZeroLHS | KnownOneLHS; |
| APInt UnknownBit = ~KnownBits; |
| if (UnknownBit.countPopulation() == 1) { |
| if (!DoXform) return ICI; |
| |
| Value *Result = Builder->CreateXor(LHS, RHS); |
| |
| // Mask off any bits that are set and won't be shifted away. |
| if (KnownOneLHS.uge(UnknownBit)) |
| Result = Builder->CreateAnd(Result, |
| ConstantInt::get(ITy, UnknownBit)); |
| |
| // Shift the bit we're testing down to the lsb. |
| Result = Builder->CreateLShr( |
| Result, ConstantInt::get(ITy, UnknownBit.countTrailingZeros())); |
| |
| if (ICI->getPredicate() == ICmpInst::ICMP_EQ) |
| Result = Builder->CreateXor(Result, ConstantInt::get(ITy, 1)); |
| Result->takeName(ICI); |
| return ReplaceInstUsesWith(CI, Result); |
| } |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitZExt(ZExtInst &CI) { |
| // If one of the common conversion will work, do it. |
| if (Instruction *Result = commonIntCastTransforms(CI)) |
| return Result; |
| |
| Value *Src = CI.getOperand(0); |
| |
| // If this is a TRUNC followed by a ZEXT then we are dealing with integral |
| // types and if the sizes are just right we can convert this into a logical |
| // 'and' which will be much cheaper than the pair of casts. |
| if (TruncInst *CSrc = dyn_cast<TruncInst>(Src)) { // A->B->C cast |
| // Get the sizes of the types involved. We know that the intermediate type |
| // will be smaller than A or C, but don't know the relation between A and C. |
| Value *A = CSrc->getOperand(0); |
| unsigned SrcSize = A->getType()->getScalarSizeInBits(); |
| unsigned MidSize = CSrc->getType()->getScalarSizeInBits(); |
| unsigned DstSize = CI.getType()->getScalarSizeInBits(); |
| // If we're actually extending zero bits, then if |
| // SrcSize < DstSize: zext(a & mask) |
| // SrcSize == DstSize: a & mask |
| // SrcSize > DstSize: trunc(a) & mask |
| if (SrcSize < DstSize) { |
| APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize)); |
| Constant *AndConst = ConstantInt::get(A->getType(), AndValue); |
| Value *And = Builder->CreateAnd(A, AndConst, CSrc->getName()+".mask"); |
| return new ZExtInst(And, CI.getType()); |
| } |
| |
| if (SrcSize == DstSize) { |
| APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize)); |
| return BinaryOperator::CreateAnd(A, ConstantInt::get(A->getType(), |
| AndValue)); |
| } |
| if (SrcSize > DstSize) { |
| Value *Trunc = Builder->CreateTrunc(A, CI.getType(), "tmp"); |
| APInt AndValue(APInt::getLowBitsSet(DstSize, MidSize)); |
| return BinaryOperator::CreateAnd(Trunc, |
| ConstantInt::get(Trunc->getType(), |
| AndValue)); |
| } |
| } |
| |
| if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src)) |
| return transformZExtICmp(ICI, CI); |
| |
| BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src); |
| if (SrcI && SrcI->getOpcode() == Instruction::Or) { |
| // zext (or icmp, icmp) --> or (zext icmp), (zext icmp) if at least one |
| // of the (zext icmp) will be transformed. |
| ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0)); |
| ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1)); |
| if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() && |
| (transformZExtICmp(LHS, CI, false) || |
| transformZExtICmp(RHS, CI, false))) { |
| Value *LCast = Builder->CreateZExt(LHS, CI.getType(), LHS->getName()); |
| Value *RCast = Builder->CreateZExt(RHS, CI.getType(), RHS->getName()); |
| return BinaryOperator::Create(Instruction::Or, LCast, RCast); |
| } |
| } |
| |
| // zext(trunc(t) & C) -> (t & zext(C)). |
| if (SrcI && SrcI->getOpcode() == Instruction::And && SrcI->hasOneUse()) |
| if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1))) |
| if (TruncInst *TI = dyn_cast<TruncInst>(SrcI->getOperand(0))) { |
| Value *TI0 = TI->getOperand(0); |
| if (TI0->getType() == CI.getType()) |
| return |
| BinaryOperator::CreateAnd(TI0, |
| ConstantExpr::getZExt(C, CI.getType())); |
| } |
| |
| // zext((trunc(t) & C) ^ C) -> ((t & zext(C)) ^ zext(C)). |
| if (SrcI && SrcI->getOpcode() == Instruction::Xor && SrcI->hasOneUse()) |
| if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1))) |
| if (BinaryOperator *And = dyn_cast<BinaryOperator>(SrcI->getOperand(0))) |
| if (And->getOpcode() == Instruction::And && And->hasOneUse() && |
| And->getOperand(1) == C) |
| if (TruncInst *TI = dyn_cast<TruncInst>(And->getOperand(0))) { |
| Value *TI0 = TI->getOperand(0); |
| if (TI0->getType() == CI.getType()) { |
| Constant *ZC = ConstantExpr::getZExt(C, CI.getType()); |
| Value *NewAnd = Builder->CreateAnd(TI0, ZC, "tmp"); |
| return BinaryOperator::CreateXor(NewAnd, ZC); |
| } |
| } |
| |
| // zext (xor i1 X, true) to i32 --> xor (zext i1 X to i32), 1 |
| Value *X; |
| if (SrcI && SrcI->hasOneUse() && SrcI->getType()->isInteger(1) && |
| match(SrcI, m_Not(m_Value(X))) && |
| (!X->hasOneUse() || !isa<CmpInst>(X))) { |
| Value *New = Builder->CreateZExt(X, CI.getType()); |
| return BinaryOperator::CreateXor(New, ConstantInt::get(CI.getType(), 1)); |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitSExt(SExtInst &CI) { |
| if (Instruction *I = commonIntCastTransforms(CI)) |
| return I; |
| |
| Value *Src = CI.getOperand(0); |
| |
| // Canonicalize sign-extend from i1 to a select. |
| if (Src->getType()->isInteger(1)) |
| return SelectInst::Create(Src, |
| Constant::getAllOnesValue(CI.getType()), |
| Constant::getNullValue(CI.getType())); |
| |
| // See if the value being truncated is already sign extended. If so, just |
| // eliminate the trunc/sext pair. |
| if (Operator::getOpcode(Src) == Instruction::Trunc) { |
| Value *Op = cast<User>(Src)->getOperand(0); |
| unsigned OpBits = Op->getType()->getScalarSizeInBits(); |
| unsigned MidBits = Src->getType()->getScalarSizeInBits(); |
| unsigned DestBits = CI.getType()->getScalarSizeInBits(); |
| unsigned NumSignBits = ComputeNumSignBits(Op); |
| |
| if (OpBits == DestBits) { |
| // Op is i32, Mid is i8, and Dest is i32. If Op has more than 24 sign |
| // bits, it is already ready. |
| if (NumSignBits > DestBits-MidBits) |
| return ReplaceInstUsesWith(CI, Op); |
| } else if (OpBits < DestBits) { |
| // Op is i32, Mid is i8, and Dest is i64. If Op has more than 24 sign |
| // bits, just sext from i32. |
| if (NumSignBits > OpBits-MidBits) |
| return new SExtInst(Op, CI.getType(), "tmp"); |
| } else { |
| // Op is i64, Mid is i8, and Dest is i32. If Op has more than 56 sign |
| // bits, just truncate to i32. |
| if (NumSignBits > OpBits-MidBits) |
| return new TruncInst(Op, CI.getType(), "tmp"); |
| } |
| } |
| |
| // If the input is a shl/ashr pair of a same constant, then this is a sign |
| // extension from a smaller value. If we could trust arbitrary bitwidth |
| // integers, we could turn this into a truncate to the smaller bit and then |
| // use a sext for the whole extension. Since we don't, look deeper and check |
| // for a truncate. If the source and dest are the same type, eliminate the |
| // trunc and extend and just do shifts. For example, turn: |
| // %a = trunc i32 %i to i8 |
| // %b = shl i8 %a, 6 |
| // %c = ashr i8 %b, 6 |
| // %d = sext i8 %c to i32 |
| // into: |
| // %a = shl i32 %i, 30 |
| // %d = ashr i32 %a, 30 |
| Value *A = 0; |
| ConstantInt *BA = 0, *CA = 0; |
| if (match(Src, m_AShr(m_Shl(m_Value(A), m_ConstantInt(BA)), |
| m_ConstantInt(CA))) && |
| BA == CA && isa<TruncInst>(A)) { |
| Value *I = cast<TruncInst>(A)->getOperand(0); |
| if (I->getType() == CI.getType()) { |
| unsigned MidSize = Src->getType()->getScalarSizeInBits(); |
| unsigned SrcDstSize = CI.getType()->getScalarSizeInBits(); |
| unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize; |
| Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt); |
| I = Builder->CreateShl(I, ShAmtV, CI.getName()); |
| return BinaryOperator::CreateAShr(I, ShAmtV); |
| } |
| } |
| |
| return 0; |
| } |
| |
| |
| /// FitsInFPType - Return a Constant* for the specified FP constant if it fits |
| /// in the specified FP type without changing its value. |
| static Constant *FitsInFPType(ConstantFP *CFP, const fltSemantics &Sem) { |
| bool losesInfo; |
| APFloat F = CFP->getValueAPF(); |
| (void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo); |
| if (!losesInfo) |
| return ConstantFP::get(CFP->getContext(), F); |
| return 0; |
| } |
| |
| /// LookThroughFPExtensions - If this is an fp extension instruction, look |
| /// through it until we get the source value. |
| static Value *LookThroughFPExtensions(Value *V) { |
| if (Instruction *I = dyn_cast<Instruction>(V)) |
| if (I->getOpcode() == Instruction::FPExt) |
| return LookThroughFPExtensions(I->getOperand(0)); |
| |
| // If this value is a constant, return the constant in the smallest FP type |
| // that can accurately represent it. This allows us to turn |
| // (float)((double)X+2.0) into x+2.0f. |
| if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) { |
| if (CFP->getType() == Type::getPPC_FP128Ty(V->getContext())) |
| return V; // No constant folding of this. |
| // See if the value can be truncated to float and then reextended. |
| if (Value *V = FitsInFPType(CFP, APFloat::IEEEsingle)) |
| return V; |
| if (CFP->getType()->isDoubleTy()) |
| return V; // Won't shrink. |
| if (Value *V = FitsInFPType(CFP, APFloat::IEEEdouble)) |
| return V; |
| // Don't try to shrink to various long double types. |
| } |
| |
| return V; |
| } |
| |
| Instruction *InstCombiner::visitFPTrunc(FPTruncInst &CI) { |
| if (Instruction *I = commonCastTransforms(CI)) |
| return I; |
| |
| // If we have fptrunc(fadd (fpextend x), (fpextend y)), where x and y are |
| // smaller than the destination type, we can eliminate the truncate by doing |
| // the add as the smaller type. This applies to fadd/fsub/fmul/fdiv as well |
| // as many builtins (sqrt, etc). |
| BinaryOperator *OpI = dyn_cast<BinaryOperator>(CI.getOperand(0)); |
| if (OpI && OpI->hasOneUse()) { |
| switch (OpI->getOpcode()) { |
| default: break; |
| case Instruction::FAdd: |
| case Instruction::FSub: |
| case Instruction::FMul: |
| case Instruction::FDiv: |
| case Instruction::FRem: |
| const Type *SrcTy = OpI->getType(); |
| Value *LHSTrunc = LookThroughFPExtensions(OpI->getOperand(0)); |
| Value *RHSTrunc = LookThroughFPExtensions(OpI->getOperand(1)); |
| if (LHSTrunc->getType() != SrcTy && |
| RHSTrunc->getType() != SrcTy) { |
| unsigned DstSize = CI.getType()->getScalarSizeInBits(); |
| // If the source types were both smaller than the destination type of |
| // the cast, do this xform. |
| if (LHSTrunc->getType()->getScalarSizeInBits() <= DstSize && |
| RHSTrunc->getType()->getScalarSizeInBits() <= DstSize) { |
| LHSTrunc = Builder->CreateFPExt(LHSTrunc, CI.getType()); |
| RHSTrunc = Builder->CreateFPExt(RHSTrunc, CI.getType()); |
| return BinaryOperator::Create(OpI->getOpcode(), LHSTrunc, RHSTrunc); |
| } |
| } |
| break; |
| } |
| } |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitFPExt(CastInst &CI) { |
| return commonCastTransforms(CI); |
| } |
| |
| Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) { |
| Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0)); |
| if (OpI == 0) |
| return commonCastTransforms(FI); |
| |
| // fptoui(uitofp(X)) --> X |
| // fptoui(sitofp(X)) --> X |
| // This is safe if the intermediate type has enough bits in its mantissa to |
| // accurately represent all values of X. For example, do not do this with |
| // i64->float->i64. This is also safe for sitofp case, because any negative |
| // 'X' value would cause an undefined result for the fptoui. |
| if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) && |
| OpI->getOperand(0)->getType() == FI.getType() && |
| (int)FI.getType()->getScalarSizeInBits() < /*extra bit for sign */ |
| OpI->getType()->getFPMantissaWidth()) |
| return ReplaceInstUsesWith(FI, OpI->getOperand(0)); |
| |
| return commonCastTransforms(FI); |
| } |
| |
| Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) { |
| Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0)); |
| if (OpI == 0) |
| return commonCastTransforms(FI); |
| |
| // fptosi(sitofp(X)) --> X |
| // fptosi(uitofp(X)) --> X |
| // This is safe if the intermediate type has enough bits in its mantissa to |
| // accurately represent all values of X. For example, do not do this with |
| // i64->float->i64. This is also safe for sitofp case, because any negative |
| // 'X' value would cause an undefined result for the fptoui. |
| if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) && |
| OpI->getOperand(0)->getType() == FI.getType() && |
| (int)FI.getType()->getScalarSizeInBits() <= |
| OpI->getType()->getFPMantissaWidth()) |
| return ReplaceInstUsesWith(FI, OpI->getOperand(0)); |
| |
| return commonCastTransforms(FI); |
| } |
| |
| Instruction *InstCombiner::visitUIToFP(CastInst &CI) { |
| return commonCastTransforms(CI); |
| } |
| |
| Instruction *InstCombiner::visitSIToFP(CastInst &CI) { |
| return commonCastTransforms(CI); |
| } |
| |
| Instruction *InstCombiner::visitPtrToInt(PtrToIntInst &CI) { |
| // If the destination integer type is smaller than the intptr_t type for |
| // this target, do a ptrtoint to intptr_t then do a trunc. This allows the |
| // trunc to be exposed to other transforms. Don't do this for extending |
| // ptrtoint's, because we don't know if the target sign or zero extends its |
| // pointers. |
| if (TD && |
| CI.getType()->getScalarSizeInBits() < TD->getPointerSizeInBits()) { |
| Value *P = Builder->CreatePtrToInt(CI.getOperand(0), |
| TD->getIntPtrType(CI.getContext()), |
| "tmp"); |
| return new TruncInst(P, CI.getType()); |
| } |
| |
| return commonPointerCastTransforms(CI); |
| } |
| |
| |
| Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) { |
| // If the source integer type is larger than the intptr_t type for |
| // this target, do a trunc to the intptr_t type, then inttoptr of it. This |
| // allows the trunc to be exposed to other transforms. Don't do this for |
| // extending inttoptr's, because we don't know if the target sign or zero |
| // extends to pointers. |
| if (TD && CI.getOperand(0)->getType()->getScalarSizeInBits() > |
| TD->getPointerSizeInBits()) { |
| Value *P = Builder->CreateTrunc(CI.getOperand(0), |
| TD->getIntPtrType(CI.getContext()), "tmp"); |
| return new IntToPtrInst(P, CI.getType()); |
| } |
| |
| if (Instruction *I = commonCastTransforms(CI)) |
| return I; |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitBitCast(BitCastInst &CI) { |
| // If the operands are integer typed then apply the integer transforms, |
| // otherwise just apply the common ones. |
| Value *Src = CI.getOperand(0); |
| const Type *SrcTy = Src->getType(); |
| const Type *DestTy = CI.getType(); |
| |
| if (isa<PointerType>(SrcTy)) { |
| if (Instruction *I = commonPointerCastTransforms(CI)) |
| return I; |
| } else { |
| if (Instruction *Result = commonCastTransforms(CI)) |
| return Result; |
| } |
| |
| |
| // Get rid of casts from one type to the same type. These are useless and can |
| // be replaced by the operand. |
| if (DestTy == Src->getType()) |
| return ReplaceInstUsesWith(CI, Src); |
| |
| if (const PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) { |
| const PointerType *SrcPTy = cast<PointerType>(SrcTy); |
| const Type *DstElTy = DstPTy->getElementType(); |
| const Type *SrcElTy = SrcPTy->getElementType(); |
| |
| // If the address spaces don't match, don't eliminate the bitcast, which is |
| // required for changing types. |
| if (SrcPTy->getAddressSpace() != DstPTy->getAddressSpace()) |
| return 0; |
| |
| // If we are casting a alloca to a pointer to a type of the same |
| // size, rewrite the allocation instruction to allocate the "right" type. |
| // There is no need to modify malloc calls because it is their bitcast that |
| // needs to be cleaned up. |
| if (AllocaInst *AI = dyn_cast<AllocaInst>(Src)) |
| if (Instruction *V = PromoteCastOfAllocation(CI, *AI)) |
| return V; |
| |
| // If the source and destination are pointers, and this cast is equivalent |
| // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep. |
| // This can enhance SROA and other transforms that want type-safe pointers. |
| Constant *ZeroUInt = |
| Constant::getNullValue(Type::getInt32Ty(CI.getContext())); |
| unsigned NumZeros = 0; |
| while (SrcElTy != DstElTy && |
| isa<CompositeType>(SrcElTy) && !isa<PointerType>(SrcElTy) && |
| SrcElTy->getNumContainedTypes() /* not "{}" */) { |
| SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt); |
| ++NumZeros; |
| } |
| |
| // If we found a path from the src to dest, create the getelementptr now. |
| if (SrcElTy == DstElTy) { |
| SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt); |
| return GetElementPtrInst::CreateInBounds(Src, Idxs.begin(), Idxs.end(),"", |
| ((Instruction*) NULL)); |
| } |
| } |
| |
| if (const VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) { |
| if (DestVTy->getNumElements() == 1) { |
| if (!isa<VectorType>(SrcTy)) { |
| Value *Elem = Builder->CreateBitCast(Src, DestVTy->getElementType()); |
| return InsertElementInst::Create(UndefValue::get(DestTy), Elem, |
| Constant::getNullValue(Type::getInt32Ty(CI.getContext()))); |
| } |
| // FIXME: Canonicalize bitcast(insertelement) -> insertelement(bitcast) |
| } |
| } |
| |
| if (const VectorType *SrcVTy = dyn_cast<VectorType>(SrcTy)) { |
| if (SrcVTy->getNumElements() == 1) { |
| if (!isa<VectorType>(DestTy)) { |
| Value *Elem = |
| Builder->CreateExtractElement(Src, |
| Constant::getNullValue(Type::getInt32Ty(CI.getContext()))); |
| return CastInst::Create(Instruction::BitCast, Elem, DestTy); |
| } |
| } |
| } |
| |
| if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) { |
| if (SVI->hasOneUse()) { |
| // Okay, we have (bitconvert (shuffle ..)). Check to see if this is |
| // a bitconvert to a vector with the same # elts. |
| if (isa<VectorType>(DestTy) && |
| cast<VectorType>(DestTy)->getNumElements() == |
| SVI->getType()->getNumElements() && |
| SVI->getType()->getNumElements() == |
| cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements()) { |
| CastInst *Tmp; |
| // If either of the operands is a cast from CI.getType(), then |
| // evaluating the shuffle in the casted destination's type will allow |
| // us to eliminate at least one cast. |
| if (((Tmp = dyn_cast<CastInst>(SVI->getOperand(0))) && |
| Tmp->getOperand(0)->getType() == DestTy) || |
| ((Tmp = dyn_cast<CastInst>(SVI->getOperand(1))) && |
| Tmp->getOperand(0)->getType() == DestTy)) { |
| Value *LHS = Builder->CreateBitCast(SVI->getOperand(0), DestTy); |
| Value *RHS = Builder->CreateBitCast(SVI->getOperand(1), DestTy); |
| // Return a new shuffle vector. Use the same element ID's, as we |
| // know the vector types match #elts. |
| return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2)); |
| } |
| } |
| } |
| } |
| return 0; |
| } |