| //===- ConstantFold.cpp - LLVM constant folder ----------------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements folding of constants for LLVM. This implements the |
| // (internal) ConstantFold.h interface, which is used by the |
| // ConstantExpr::get* methods to automatically fold constants when possible. |
| // |
| // The current constant folding implementation is implemented in two pieces: the |
| // pieces that don't need TargetData, and the pieces that do. This is to avoid |
| // a dependence in VMCore on Target. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "ConstantFold.h" |
| #include "llvm/Constants.h" |
| #include "llvm/Instructions.h" |
| #include "llvm/DerivedTypes.h" |
| #include "llvm/Function.h" |
| #include "llvm/GlobalAlias.h" |
| #include "llvm/GlobalVariable.h" |
| #include "llvm/Operator.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/Support/Compiler.h" |
| #include "llvm/Support/ErrorHandling.h" |
| #include "llvm/Support/GetElementPtrTypeIterator.h" |
| #include "llvm/Support/ManagedStatic.h" |
| #include "llvm/Support/MathExtras.h" |
| #include <limits> |
| using namespace llvm; |
| |
| //===----------------------------------------------------------------------===// |
| // ConstantFold*Instruction Implementations |
| //===----------------------------------------------------------------------===// |
| |
| /// BitCastConstantVector - Convert the specified ConstantVector node to the |
| /// specified vector type. At this point, we know that the elements of the |
| /// input vector constant are all simple integer or FP values. |
| static Constant *BitCastConstantVector(ConstantVector *CV, |
| VectorType *DstTy) { |
| |
| if (CV->isAllOnesValue()) return Constant::getAllOnesValue(DstTy); |
| if (CV->isNullValue()) return Constant::getNullValue(DstTy); |
| |
| // If this cast changes element count then we can't handle it here: |
| // doing so requires endianness information. This should be handled by |
| // Analysis/ConstantFolding.cpp |
| unsigned NumElts = DstTy->getNumElements(); |
| if (NumElts != CV->getNumOperands()) |
| return 0; |
| |
| // Check to verify that all elements of the input are simple. |
| for (unsigned i = 0; i != NumElts; ++i) { |
| if (!isa<ConstantInt>(CV->getOperand(i)) && |
| !isa<ConstantFP>(CV->getOperand(i))) |
| return 0; |
| } |
| |
| // Bitcast each element now. |
| std::vector<Constant*> Result; |
| Type *DstEltTy = DstTy->getElementType(); |
| for (unsigned i = 0; i != NumElts; ++i) |
| Result.push_back(ConstantExpr::getBitCast(CV->getOperand(i), |
| DstEltTy)); |
| return ConstantVector::get(Result); |
| } |
| |
| /// This function determines which opcode to use to fold two constant cast |
| /// expressions together. It uses CastInst::isEliminableCastPair to determine |
| /// the opcode. Consequently its just a wrapper around that function. |
| /// @brief Determine if it is valid to fold a cast of a cast |
| static unsigned |
| foldConstantCastPair( |
| unsigned opc, ///< opcode of the second cast constant expression |
| ConstantExpr *Op, ///< the first cast constant expression |
| Type *DstTy ///< desintation type of the first cast |
| ) { |
| assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!"); |
| assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type"); |
| assert(CastInst::isCast(opc) && "Invalid cast opcode"); |
| |
| // The the types and opcodes for the two Cast constant expressions |
| Type *SrcTy = Op->getOperand(0)->getType(); |
| Type *MidTy = Op->getType(); |
| Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode()); |
| Instruction::CastOps secondOp = Instruction::CastOps(opc); |
| |
| // Let CastInst::isEliminableCastPair do the heavy lifting. |
| return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy, |
| Type::getInt64Ty(DstTy->getContext())); |
| } |
| |
| static Constant *FoldBitCast(Constant *V, Type *DestTy) { |
| Type *SrcTy = V->getType(); |
| if (SrcTy == DestTy) |
| return V; // no-op cast |
| |
| // Check to see if we are casting a pointer to an aggregate to a pointer to |
| // the first element. If so, return the appropriate GEP instruction. |
| if (PointerType *PTy = dyn_cast<PointerType>(V->getType())) |
| if (PointerType *DPTy = dyn_cast<PointerType>(DestTy)) |
| if (PTy->getAddressSpace() == DPTy->getAddressSpace()) { |
| SmallVector<Value*, 8> IdxList; |
| Value *Zero = |
| Constant::getNullValue(Type::getInt32Ty(DPTy->getContext())); |
| IdxList.push_back(Zero); |
| Type *ElTy = PTy->getElementType(); |
| while (ElTy != DPTy->getElementType()) { |
| if (StructType *STy = dyn_cast<StructType>(ElTy)) { |
| if (STy->getNumElements() == 0) break; |
| ElTy = STy->getElementType(0); |
| IdxList.push_back(Zero); |
| } else if (SequentialType *STy = |
| dyn_cast<SequentialType>(ElTy)) { |
| if (ElTy->isPointerTy()) break; // Can't index into pointers! |
| ElTy = STy->getElementType(); |
| IdxList.push_back(Zero); |
| } else { |
| break; |
| } |
| } |
| |
| if (ElTy == DPTy->getElementType()) |
| // This GEP is inbounds because all indices are zero. |
| return ConstantExpr::getInBoundsGetElementPtr(V, &IdxList[0], |
| IdxList.size()); |
| } |
| |
| // Handle casts from one vector constant to another. We know that the src |
| // and dest type have the same size (otherwise its an illegal cast). |
| if (VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) { |
| if (VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) { |
| assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() && |
| "Not cast between same sized vectors!"); |
| SrcTy = NULL; |
| // First, check for null. Undef is already handled. |
| if (isa<ConstantAggregateZero>(V)) |
| return Constant::getNullValue(DestTy); |
| |
| if (ConstantVector *CV = dyn_cast<ConstantVector>(V)) |
| return BitCastConstantVector(CV, DestPTy); |
| } |
| |
| // Canonicalize scalar-to-vector bitcasts into vector-to-vector bitcasts |
| // This allows for other simplifications (although some of them |
| // can only be handled by Analysis/ConstantFolding.cpp). |
| if (isa<ConstantInt>(V) || isa<ConstantFP>(V)) |
| return ConstantExpr::getBitCast(ConstantVector::get(V), DestPTy); |
| } |
| |
| // Finally, implement bitcast folding now. The code below doesn't handle |
| // bitcast right. |
| if (isa<ConstantPointerNull>(V)) // ptr->ptr cast. |
| return ConstantPointerNull::get(cast<PointerType>(DestTy)); |
| |
| // Handle integral constant input. |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { |
| if (DestTy->isIntegerTy()) |
| // Integral -> Integral. This is a no-op because the bit widths must |
| // be the same. Consequently, we just fold to V. |
| return V; |
| |
| if (DestTy->isFloatingPointTy()) |
| return ConstantFP::get(DestTy->getContext(), |
| APFloat(CI->getValue(), |
| !DestTy->isPPC_FP128Ty())); |
| |
| // Otherwise, can't fold this (vector?) |
| return 0; |
| } |
| |
| // Handle ConstantFP input: FP -> Integral. |
| if (ConstantFP *FP = dyn_cast<ConstantFP>(V)) |
| return ConstantInt::get(FP->getContext(), |
| FP->getValueAPF().bitcastToAPInt()); |
| |
| return 0; |
| } |
| |
| |
| /// ExtractConstantBytes - V is an integer constant which only has a subset of |
| /// its bytes used. The bytes used are indicated by ByteStart (which is the |
| /// first byte used, counting from the least significant byte) and ByteSize, |
| /// which is the number of bytes used. |
| /// |
| /// This function analyzes the specified constant to see if the specified byte |
| /// range can be returned as a simplified constant. If so, the constant is |
| /// returned, otherwise null is returned. |
| /// |
| static Constant *ExtractConstantBytes(Constant *C, unsigned ByteStart, |
| unsigned ByteSize) { |
| assert(C->getType()->isIntegerTy() && |
| (cast<IntegerType>(C->getType())->getBitWidth() & 7) == 0 && |
| "Non-byte sized integer input"); |
| unsigned CSize = cast<IntegerType>(C->getType())->getBitWidth()/8; |
| assert(ByteSize && "Must be accessing some piece"); |
| assert(ByteStart+ByteSize <= CSize && "Extracting invalid piece from input"); |
| assert(ByteSize != CSize && "Should not extract everything"); |
| |
| // Constant Integers are simple. |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) { |
| APInt V = CI->getValue(); |
| if (ByteStart) |
| V = V.lshr(ByteStart*8); |
| V = V.trunc(ByteSize*8); |
| return ConstantInt::get(CI->getContext(), V); |
| } |
| |
| // In the input is a constant expr, we might be able to recursively simplify. |
| // If not, we definitely can't do anything. |
| ConstantExpr *CE = dyn_cast<ConstantExpr>(C); |
| if (CE == 0) return 0; |
| |
| switch (CE->getOpcode()) { |
| default: return 0; |
| case Instruction::Or: { |
| Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize); |
| if (RHS == 0) |
| return 0; |
| |
| // X | -1 -> -1. |
| if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) |
| if (RHSC->isAllOnesValue()) |
| return RHSC; |
| |
| Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize); |
| if (LHS == 0) |
| return 0; |
| return ConstantExpr::getOr(LHS, RHS); |
| } |
| case Instruction::And: { |
| Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize); |
| if (RHS == 0) |
| return 0; |
| |
| // X & 0 -> 0. |
| if (RHS->isNullValue()) |
| return RHS; |
| |
| Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize); |
| if (LHS == 0) |
| return 0; |
| return ConstantExpr::getAnd(LHS, RHS); |
| } |
| case Instruction::LShr: { |
| ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1)); |
| if (Amt == 0) |
| return 0; |
| unsigned ShAmt = Amt->getZExtValue(); |
| // Cannot analyze non-byte shifts. |
| if ((ShAmt & 7) != 0) |
| return 0; |
| ShAmt >>= 3; |
| |
| // If the extract is known to be all zeros, return zero. |
| if (ByteStart >= CSize-ShAmt) |
| return Constant::getNullValue(IntegerType::get(CE->getContext(), |
| ByteSize*8)); |
| // If the extract is known to be fully in the input, extract it. |
| if (ByteStart+ByteSize+ShAmt <= CSize) |
| return ExtractConstantBytes(CE->getOperand(0), ByteStart+ShAmt, ByteSize); |
| |
| // TODO: Handle the 'partially zero' case. |
| return 0; |
| } |
| |
| case Instruction::Shl: { |
| ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1)); |
| if (Amt == 0) |
| return 0; |
| unsigned ShAmt = Amt->getZExtValue(); |
| // Cannot analyze non-byte shifts. |
| if ((ShAmt & 7) != 0) |
| return 0; |
| ShAmt >>= 3; |
| |
| // If the extract is known to be all zeros, return zero. |
| if (ByteStart+ByteSize <= ShAmt) |
| return Constant::getNullValue(IntegerType::get(CE->getContext(), |
| ByteSize*8)); |
| // If the extract is known to be fully in the input, extract it. |
| if (ByteStart >= ShAmt) |
| return ExtractConstantBytes(CE->getOperand(0), ByteStart-ShAmt, ByteSize); |
| |
| // TODO: Handle the 'partially zero' case. |
| return 0; |
| } |
| |
| case Instruction::ZExt: { |
| unsigned SrcBitSize = |
| cast<IntegerType>(CE->getOperand(0)->getType())->getBitWidth(); |
| |
| // If extracting something that is completely zero, return 0. |
| if (ByteStart*8 >= SrcBitSize) |
| return Constant::getNullValue(IntegerType::get(CE->getContext(), |
| ByteSize*8)); |
| |
| // If exactly extracting the input, return it. |
| if (ByteStart == 0 && ByteSize*8 == SrcBitSize) |
| return CE->getOperand(0); |
| |
| // If extracting something completely in the input, if if the input is a |
| // multiple of 8 bits, recurse. |
| if ((SrcBitSize&7) == 0 && (ByteStart+ByteSize)*8 <= SrcBitSize) |
| return ExtractConstantBytes(CE->getOperand(0), ByteStart, ByteSize); |
| |
| // Otherwise, if extracting a subset of the input, which is not multiple of |
| // 8 bits, do a shift and trunc to get the bits. |
| if ((ByteStart+ByteSize)*8 < SrcBitSize) { |
| assert((SrcBitSize&7) && "Shouldn't get byte sized case here"); |
| Constant *Res = CE->getOperand(0); |
| if (ByteStart) |
| Res = ConstantExpr::getLShr(Res, |
| ConstantInt::get(Res->getType(), ByteStart*8)); |
| return ConstantExpr::getTrunc(Res, IntegerType::get(C->getContext(), |
| ByteSize*8)); |
| } |
| |
| // TODO: Handle the 'partially zero' case. |
| return 0; |
| } |
| } |
| } |
| |
| /// getFoldedSizeOf - Return a ConstantExpr with type DestTy for sizeof |
| /// on Ty, with any known factors factored out. If Folded is false, |
| /// return null if no factoring was possible, to avoid endlessly |
| /// bouncing an unfoldable expression back into the top-level folder. |
| /// |
| static Constant *getFoldedSizeOf(Type *Ty, Type *DestTy, |
| bool Folded) { |
| if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { |
| Constant *N = ConstantInt::get(DestTy, ATy->getNumElements()); |
| Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true); |
| return ConstantExpr::getNUWMul(E, N); |
| } |
| |
| if (StructType *STy = dyn_cast<StructType>(Ty)) |
| if (!STy->isPacked()) { |
| unsigned NumElems = STy->getNumElements(); |
| // An empty struct has size zero. |
| if (NumElems == 0) |
| return ConstantExpr::getNullValue(DestTy); |
| // Check for a struct with all members having the same size. |
| Constant *MemberSize = |
| getFoldedSizeOf(STy->getElementType(0), DestTy, true); |
| bool AllSame = true; |
| for (unsigned i = 1; i != NumElems; ++i) |
| if (MemberSize != |
| getFoldedSizeOf(STy->getElementType(i), DestTy, true)) { |
| AllSame = false; |
| break; |
| } |
| if (AllSame) { |
| Constant *N = ConstantInt::get(DestTy, NumElems); |
| return ConstantExpr::getNUWMul(MemberSize, N); |
| } |
| } |
| |
| // Pointer size doesn't depend on the pointee type, so canonicalize them |
| // to an arbitrary pointee. |
| if (PointerType *PTy = dyn_cast<PointerType>(Ty)) |
| if (!PTy->getElementType()->isIntegerTy(1)) |
| return |
| getFoldedSizeOf(PointerType::get(IntegerType::get(PTy->getContext(), 1), |
| PTy->getAddressSpace()), |
| DestTy, true); |
| |
| // If there's no interesting folding happening, bail so that we don't create |
| // a constant that looks like it needs folding but really doesn't. |
| if (!Folded) |
| return 0; |
| |
| // Base case: Get a regular sizeof expression. |
| Constant *C = ConstantExpr::getSizeOf(Ty); |
| C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, |
| DestTy, false), |
| C, DestTy); |
| return C; |
| } |
| |
| /// getFoldedAlignOf - Return a ConstantExpr with type DestTy for alignof |
| /// on Ty, with any known factors factored out. If Folded is false, |
| /// return null if no factoring was possible, to avoid endlessly |
| /// bouncing an unfoldable expression back into the top-level folder. |
| /// |
| static Constant *getFoldedAlignOf(Type *Ty, Type *DestTy, |
| bool Folded) { |
| // The alignment of an array is equal to the alignment of the |
| // array element. Note that this is not always true for vectors. |
| if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { |
| Constant *C = ConstantExpr::getAlignOf(ATy->getElementType()); |
| C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, |
| DestTy, |
| false), |
| C, DestTy); |
| return C; |
| } |
| |
| if (StructType *STy = dyn_cast<StructType>(Ty)) { |
| // Packed structs always have an alignment of 1. |
| if (STy->isPacked()) |
| return ConstantInt::get(DestTy, 1); |
| |
| // Otherwise, struct alignment is the maximum alignment of any member. |
| // Without target data, we can't compare much, but we can check to see |
| // if all the members have the same alignment. |
| unsigned NumElems = STy->getNumElements(); |
| // An empty struct has minimal alignment. |
| if (NumElems == 0) |
| return ConstantInt::get(DestTy, 1); |
| // Check for a struct with all members having the same alignment. |
| Constant *MemberAlign = |
| getFoldedAlignOf(STy->getElementType(0), DestTy, true); |
| bool AllSame = true; |
| for (unsigned i = 1; i != NumElems; ++i) |
| if (MemberAlign != getFoldedAlignOf(STy->getElementType(i), DestTy, true)) { |
| AllSame = false; |
| break; |
| } |
| if (AllSame) |
| return MemberAlign; |
| } |
| |
| // Pointer alignment doesn't depend on the pointee type, so canonicalize them |
| // to an arbitrary pointee. |
| if (PointerType *PTy = dyn_cast<PointerType>(Ty)) |
| if (!PTy->getElementType()->isIntegerTy(1)) |
| return |
| getFoldedAlignOf(PointerType::get(IntegerType::get(PTy->getContext(), |
| 1), |
| PTy->getAddressSpace()), |
| DestTy, true); |
| |
| // If there's no interesting folding happening, bail so that we don't create |
| // a constant that looks like it needs folding but really doesn't. |
| if (!Folded) |
| return 0; |
| |
| // Base case: Get a regular alignof expression. |
| Constant *C = ConstantExpr::getAlignOf(Ty); |
| C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, |
| DestTy, false), |
| C, DestTy); |
| return C; |
| } |
| |
| /// getFoldedOffsetOf - Return a ConstantExpr with type DestTy for offsetof |
| /// on Ty and FieldNo, with any known factors factored out. If Folded is false, |
| /// return null if no factoring was possible, to avoid endlessly |
| /// bouncing an unfoldable expression back into the top-level folder. |
| /// |
| static Constant *getFoldedOffsetOf(Type *Ty, Constant *FieldNo, |
| Type *DestTy, |
| bool Folded) { |
| if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { |
| Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo, false, |
| DestTy, false), |
| FieldNo, DestTy); |
| Constant *E = getFoldedSizeOf(ATy->getElementType(), DestTy, true); |
| return ConstantExpr::getNUWMul(E, N); |
| } |
| |
| if (StructType *STy = dyn_cast<StructType>(Ty)) |
| if (!STy->isPacked()) { |
| unsigned NumElems = STy->getNumElements(); |
| // An empty struct has no members. |
| if (NumElems == 0) |
| return 0; |
| // Check for a struct with all members having the same size. |
| Constant *MemberSize = |
| getFoldedSizeOf(STy->getElementType(0), DestTy, true); |
| bool AllSame = true; |
| for (unsigned i = 1; i != NumElems; ++i) |
| if (MemberSize != |
| getFoldedSizeOf(STy->getElementType(i), DestTy, true)) { |
| AllSame = false; |
| break; |
| } |
| if (AllSame) { |
| Constant *N = ConstantExpr::getCast(CastInst::getCastOpcode(FieldNo, |
| false, |
| DestTy, |
| false), |
| FieldNo, DestTy); |
| return ConstantExpr::getNUWMul(MemberSize, N); |
| } |
| } |
| |
| // If there's no interesting folding happening, bail so that we don't create |
| // a constant that looks like it needs folding but really doesn't. |
| if (!Folded) |
| return 0; |
| |
| // Base case: Get a regular offsetof expression. |
| Constant *C = ConstantExpr::getOffsetOf(Ty, FieldNo); |
| C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, |
| DestTy, false), |
| C, DestTy); |
| return C; |
| } |
| |
| Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V, |
| Type *DestTy) { |
| if (isa<UndefValue>(V)) { |
| // zext(undef) = 0, because the top bits will be zero. |
| // sext(undef) = 0, because the top bits will all be the same. |
| // [us]itofp(undef) = 0, because the result value is bounded. |
| if (opc == Instruction::ZExt || opc == Instruction::SExt || |
| opc == Instruction::UIToFP || opc == Instruction::SIToFP) |
| return Constant::getNullValue(DestTy); |
| return UndefValue::get(DestTy); |
| } |
| |
| // No compile-time operations on this type yet. |
| if (V->getType()->isPPC_FP128Ty() || DestTy->isPPC_FP128Ty()) |
| return 0; |
| |
| if (V->isNullValue() && !DestTy->isX86_MMXTy()) |
| return Constant::getNullValue(DestTy); |
| |
| // If the cast operand is a constant expression, there's a few things we can |
| // do to try to simplify it. |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { |
| if (CE->isCast()) { |
| // Try hard to fold cast of cast because they are often eliminable. |
| if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy)) |
| return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy); |
| } else if (CE->getOpcode() == Instruction::GetElementPtr) { |
| // If all of the indexes in the GEP are null values, there is no pointer |
| // adjustment going on. We might as well cast the source pointer. |
| bool isAllNull = true; |
| for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i) |
| if (!CE->getOperand(i)->isNullValue()) { |
| isAllNull = false; |
| break; |
| } |
| if (isAllNull) |
| // This is casting one pointer type to another, always BitCast |
| return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy); |
| } |
| } |
| |
| // If the cast operand is a constant vector, perform the cast by |
| // operating on each element. In the cast of bitcasts, the element |
| // count may be mismatched; don't attempt to handle that here. |
| if (ConstantVector *CV = dyn_cast<ConstantVector>(V)) |
| if (DestTy->isVectorTy() && |
| cast<VectorType>(DestTy)->getNumElements() == |
| CV->getType()->getNumElements()) { |
| std::vector<Constant*> res; |
| VectorType *DestVecTy = cast<VectorType>(DestTy); |
| Type *DstEltTy = DestVecTy->getElementType(); |
| for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i) |
| res.push_back(ConstantExpr::getCast(opc, |
| CV->getOperand(i), DstEltTy)); |
| return ConstantVector::get(res); |
| } |
| |
| // We actually have to do a cast now. Perform the cast according to the |
| // opcode specified. |
| switch (opc) { |
| default: |
| llvm_unreachable("Failed to cast constant expression"); |
| case Instruction::FPTrunc: |
| case Instruction::FPExt: |
| if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { |
| bool ignored; |
| APFloat Val = FPC->getValueAPF(); |
| Val.convert(DestTy->isFloatTy() ? APFloat::IEEEsingle : |
| DestTy->isDoubleTy() ? APFloat::IEEEdouble : |
| DestTy->isX86_FP80Ty() ? APFloat::x87DoubleExtended : |
| DestTy->isFP128Ty() ? APFloat::IEEEquad : |
| APFloat::Bogus, |
| APFloat::rmNearestTiesToEven, &ignored); |
| return ConstantFP::get(V->getContext(), Val); |
| } |
| return 0; // Can't fold. |
| case Instruction::FPToUI: |
| case Instruction::FPToSI: |
| if (ConstantFP *FPC = dyn_cast<ConstantFP>(V)) { |
| const APFloat &V = FPC->getValueAPF(); |
| bool ignored; |
| uint64_t x[2]; |
| uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); |
| (void) V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI, |
| APFloat::rmTowardZero, &ignored); |
| APInt Val(DestBitWidth, x); |
| return ConstantInt::get(FPC->getContext(), Val); |
| } |
| return 0; // Can't fold. |
| case Instruction::IntToPtr: //always treated as unsigned |
| if (V->isNullValue()) // Is it an integral null value? |
| return ConstantPointerNull::get(cast<PointerType>(DestTy)); |
| return 0; // Other pointer types cannot be casted |
| case Instruction::PtrToInt: // always treated as unsigned |
| // Is it a null pointer value? |
| if (V->isNullValue()) |
| return ConstantInt::get(DestTy, 0); |
| // If this is a sizeof-like expression, pull out multiplications by |
| // known factors to expose them to subsequent folding. If it's an |
| // alignof-like expression, factor out known factors. |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) |
| if (CE->getOpcode() == Instruction::GetElementPtr && |
| CE->getOperand(0)->isNullValue()) { |
| Type *Ty = |
| cast<PointerType>(CE->getOperand(0)->getType())->getElementType(); |
| if (CE->getNumOperands() == 2) { |
| // Handle a sizeof-like expression. |
| Constant *Idx = CE->getOperand(1); |
| bool isOne = isa<ConstantInt>(Idx) && cast<ConstantInt>(Idx)->isOne(); |
| if (Constant *C = getFoldedSizeOf(Ty, DestTy, !isOne)) { |
| Idx = ConstantExpr::getCast(CastInst::getCastOpcode(Idx, true, |
| DestTy, false), |
| Idx, DestTy); |
| return ConstantExpr::getMul(C, Idx); |
| } |
| } else if (CE->getNumOperands() == 3 && |
| CE->getOperand(1)->isNullValue()) { |
| // Handle an alignof-like expression. |
| if (StructType *STy = dyn_cast<StructType>(Ty)) |
| if (!STy->isPacked()) { |
| ConstantInt *CI = cast<ConstantInt>(CE->getOperand(2)); |
| if (CI->isOne() && |
| STy->getNumElements() == 2 && |
| STy->getElementType(0)->isIntegerTy(1)) { |
| return getFoldedAlignOf(STy->getElementType(1), DestTy, false); |
| } |
| } |
| // Handle an offsetof-like expression. |
| if (Ty->isStructTy() || Ty->isArrayTy()) { |
| if (Constant *C = getFoldedOffsetOf(Ty, CE->getOperand(2), |
| DestTy, false)) |
| return C; |
| } |
| } |
| } |
| // Other pointer types cannot be casted |
| return 0; |
| case Instruction::UIToFP: |
| case Instruction::SIToFP: |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { |
| APInt api = CI->getValue(); |
| APFloat apf(APInt::getNullValue(DestTy->getPrimitiveSizeInBits()), true); |
| (void)apf.convertFromAPInt(api, |
| opc==Instruction::SIToFP, |
| APFloat::rmNearestTiesToEven); |
| return ConstantFP::get(V->getContext(), apf); |
| } |
| return 0; |
| case Instruction::ZExt: |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { |
| uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); |
| return ConstantInt::get(V->getContext(), |
| CI->getValue().zext(BitWidth)); |
| } |
| return 0; |
| case Instruction::SExt: |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { |
| uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth(); |
| return ConstantInt::get(V->getContext(), |
| CI->getValue().sext(BitWidth)); |
| } |
| return 0; |
| case Instruction::Trunc: { |
| uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { |
| return ConstantInt::get(V->getContext(), |
| CI->getValue().trunc(DestBitWidth)); |
| } |
| |
| // The input must be a constantexpr. See if we can simplify this based on |
| // the bytes we are demanding. Only do this if the source and dest are an |
| // even multiple of a byte. |
| if ((DestBitWidth & 7) == 0 && |
| (cast<IntegerType>(V->getType())->getBitWidth() & 7) == 0) |
| if (Constant *Res = ExtractConstantBytes(V, 0, DestBitWidth / 8)) |
| return Res; |
| |
| return 0; |
| } |
| case Instruction::BitCast: |
| return FoldBitCast(V, DestTy); |
| } |
| } |
| |
| Constant *llvm::ConstantFoldSelectInstruction(Constant *Cond, |
| Constant *V1, Constant *V2) { |
| if (ConstantInt *CB = dyn_cast<ConstantInt>(Cond)) |
| return CB->getZExtValue() ? V1 : V2; |
| |
| // Check for zero aggregate and ConstantVector of zeros |
| if (Cond->isNullValue()) return V2; |
| |
| if (ConstantVector* CondV = dyn_cast<ConstantVector>(Cond)) { |
| |
| if (CondV->isAllOnesValue()) return V1; |
| |
| VectorType *VTy = cast<VectorType>(V1->getType()); |
| ConstantVector *CP1 = dyn_cast<ConstantVector>(V1); |
| ConstantVector *CP2 = dyn_cast<ConstantVector>(V2); |
| |
| if ((CP1 || isa<ConstantAggregateZero>(V1)) && |
| (CP2 || isa<ConstantAggregateZero>(V2))) { |
| |
| // Find the element type of the returned vector |
| Type *EltTy = VTy->getElementType(); |
| unsigned NumElem = VTy->getNumElements(); |
| std::vector<Constant*> Res(NumElem); |
| |
| bool Valid = true; |
| for (unsigned i = 0; i < NumElem; ++i) { |
| ConstantInt* c = dyn_cast<ConstantInt>(CondV->getOperand(i)); |
| if (!c) { |
| Valid = false; |
| break; |
| } |
| Constant *C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| Constant *C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res[i] = c->getZExtValue() ? C1 : C2; |
| } |
| // If we were able to build the vector, return it |
| if (Valid) return ConstantVector::get(Res); |
| } |
| } |
| |
| |
| if (isa<UndefValue>(Cond)) { |
| if (isa<UndefValue>(V1)) return V1; |
| return V2; |
| } |
| if (isa<UndefValue>(V1)) return V2; |
| if (isa<UndefValue>(V2)) return V1; |
| if (V1 == V2) return V1; |
| |
| if (ConstantExpr *TrueVal = dyn_cast<ConstantExpr>(V1)) { |
| if (TrueVal->getOpcode() == Instruction::Select) |
| if (TrueVal->getOperand(0) == Cond) |
| return ConstantExpr::getSelect(Cond, TrueVal->getOperand(1), V2); |
| } |
| if (ConstantExpr *FalseVal = dyn_cast<ConstantExpr>(V2)) { |
| if (FalseVal->getOpcode() == Instruction::Select) |
| if (FalseVal->getOperand(0) == Cond) |
| return ConstantExpr::getSelect(Cond, V1, FalseVal->getOperand(2)); |
| } |
| |
| return 0; |
| } |
| |
| Constant *llvm::ConstantFoldExtractElementInstruction(Constant *Val, |
| Constant *Idx) { |
| if (isa<UndefValue>(Val)) // ee(undef, x) -> undef |
| return UndefValue::get(cast<VectorType>(Val->getType())->getElementType()); |
| if (Val->isNullValue()) // ee(zero, x) -> zero |
| return Constant::getNullValue( |
| cast<VectorType>(Val->getType())->getElementType()); |
| |
| if (ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) { |
| if (ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) { |
| return CVal->getOperand(CIdx->getZExtValue()); |
| } else if (isa<UndefValue>(Idx)) { |
| // ee({w,x,y,z}, undef) -> w (an arbitrary value). |
| return CVal->getOperand(0); |
| } |
| } |
| return 0; |
| } |
| |
| Constant *llvm::ConstantFoldInsertElementInstruction(Constant *Val, |
| Constant *Elt, |
| Constant *Idx) { |
| ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx); |
| if (!CIdx) return 0; |
| APInt idxVal = CIdx->getValue(); |
| if (isa<UndefValue>(Val)) { |
| // Insertion of scalar constant into vector undef |
| // Optimize away insertion of undef |
| if (isa<UndefValue>(Elt)) |
| return Val; |
| // Otherwise break the aggregate undef into multiple undefs and do |
| // the insertion |
| unsigned numOps = |
| cast<VectorType>(Val->getType())->getNumElements(); |
| std::vector<Constant*> Ops; |
| Ops.reserve(numOps); |
| for (unsigned i = 0; i < numOps; ++i) { |
| Constant *Op = |
| (idxVal == i) ? Elt : UndefValue::get(Elt->getType()); |
| Ops.push_back(Op); |
| } |
| return ConstantVector::get(Ops); |
| } |
| if (isa<ConstantAggregateZero>(Val)) { |
| // Insertion of scalar constant into vector aggregate zero |
| // Optimize away insertion of zero |
| if (Elt->isNullValue()) |
| return Val; |
| // Otherwise break the aggregate zero into multiple zeros and do |
| // the insertion |
| unsigned numOps = |
| cast<VectorType>(Val->getType())->getNumElements(); |
| std::vector<Constant*> Ops; |
| Ops.reserve(numOps); |
| for (unsigned i = 0; i < numOps; ++i) { |
| Constant *Op = |
| (idxVal == i) ? Elt : Constant::getNullValue(Elt->getType()); |
| Ops.push_back(Op); |
| } |
| return ConstantVector::get(Ops); |
| } |
| if (ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) { |
| // Insertion of scalar constant into vector constant |
| std::vector<Constant*> Ops; |
| Ops.reserve(CVal->getNumOperands()); |
| for (unsigned i = 0; i < CVal->getNumOperands(); ++i) { |
| Constant *Op = |
| (idxVal == i) ? Elt : cast<Constant>(CVal->getOperand(i)); |
| Ops.push_back(Op); |
| } |
| return ConstantVector::get(Ops); |
| } |
| |
| return 0; |
| } |
| |
| /// GetVectorElement - If C is a ConstantVector, ConstantAggregateZero or Undef |
| /// return the specified element value. Otherwise return null. |
| static Constant *GetVectorElement(Constant *C, unsigned EltNo) { |
| if (ConstantVector *CV = dyn_cast<ConstantVector>(C)) |
| return CV->getOperand(EltNo); |
| |
| Type *EltTy = cast<VectorType>(C->getType())->getElementType(); |
| if (isa<ConstantAggregateZero>(C)) |
| return Constant::getNullValue(EltTy); |
| if (isa<UndefValue>(C)) |
| return UndefValue::get(EltTy); |
| return 0; |
| } |
| |
| Constant *llvm::ConstantFoldShuffleVectorInstruction(Constant *V1, |
| Constant *V2, |
| Constant *Mask) { |
| // Undefined shuffle mask -> undefined value. |
| if (isa<UndefValue>(Mask)) return UndefValue::get(V1->getType()); |
| |
| unsigned MaskNumElts = cast<VectorType>(Mask->getType())->getNumElements(); |
| unsigned SrcNumElts = cast<VectorType>(V1->getType())->getNumElements(); |
| Type *EltTy = cast<VectorType>(V1->getType())->getElementType(); |
| |
| // Loop over the shuffle mask, evaluating each element. |
| SmallVector<Constant*, 32> Result; |
| for (unsigned i = 0; i != MaskNumElts; ++i) { |
| Constant *InElt = GetVectorElement(Mask, i); |
| if (InElt == 0) return 0; |
| |
| if (isa<UndefValue>(InElt)) |
| InElt = UndefValue::get(EltTy); |
| else if (ConstantInt *CI = dyn_cast<ConstantInt>(InElt)) { |
| unsigned Elt = CI->getZExtValue(); |
| if (Elt >= SrcNumElts*2) |
| InElt = UndefValue::get(EltTy); |
| else if (Elt >= SrcNumElts) |
| InElt = GetVectorElement(V2, Elt - SrcNumElts); |
| else |
| InElt = GetVectorElement(V1, Elt); |
| if (InElt == 0) return 0; |
| } else { |
| // Unknown value. |
| return 0; |
| } |
| Result.push_back(InElt); |
| } |
| |
| return ConstantVector::get(Result); |
| } |
| |
| Constant *llvm::ConstantFoldExtractValueInstruction(Constant *Agg, |
| ArrayRef<unsigned> Idxs) { |
| // Base case: no indices, so return the entire value. |
| if (Idxs.empty()) |
| return Agg; |
| |
| if (isa<UndefValue>(Agg)) // ev(undef, x) -> undef |
| return UndefValue::get(ExtractValueInst::getIndexedType(Agg->getType(), |
| Idxs)); |
| |
| if (isa<ConstantAggregateZero>(Agg)) // ev(0, x) -> 0 |
| return |
| Constant::getNullValue(ExtractValueInst::getIndexedType(Agg->getType(), |
| Idxs)); |
| |
| // Otherwise recurse. |
| if (ConstantStruct *CS = dyn_cast<ConstantStruct>(Agg)) |
| return ConstantFoldExtractValueInstruction(CS->getOperand(Idxs[0]), |
| Idxs.slice(1)); |
| |
| if (ConstantArray *CA = dyn_cast<ConstantArray>(Agg)) |
| return ConstantFoldExtractValueInstruction(CA->getOperand(Idxs[0]), |
| Idxs.slice(1)); |
| ConstantVector *CV = cast<ConstantVector>(Agg); |
| return ConstantFoldExtractValueInstruction(CV->getOperand(Idxs[0]), |
| Idxs.slice(1)); |
| } |
| |
| Constant *llvm::ConstantFoldInsertValueInstruction(Constant *Agg, |
| Constant *Val, |
| ArrayRef<unsigned> Idxs) { |
| // Base case: no indices, so replace the entire value. |
| if (Idxs.empty()) |
| return Val; |
| |
| if (isa<UndefValue>(Agg)) { |
| // Insertion of constant into aggregate undef |
| // Optimize away insertion of undef. |
| if (isa<UndefValue>(Val)) |
| return Agg; |
| |
| // Otherwise break the aggregate undef into multiple undefs and do |
| // the insertion. |
| CompositeType *AggTy = cast<CompositeType>(Agg->getType()); |
| unsigned numOps; |
| if (ArrayType *AR = dyn_cast<ArrayType>(AggTy)) |
| numOps = AR->getNumElements(); |
| else |
| numOps = cast<StructType>(AggTy)->getNumElements(); |
| |
| std::vector<Constant*> Ops(numOps); |
| for (unsigned i = 0; i < numOps; ++i) { |
| Type *MemberTy = AggTy->getTypeAtIndex(i); |
| Constant *Op = |
| (Idxs[0] == i) ? |
| ConstantFoldInsertValueInstruction(UndefValue::get(MemberTy), |
| Val, Idxs.slice(1)) : |
| UndefValue::get(MemberTy); |
| Ops[i] = Op; |
| } |
| |
| if (StructType* ST = dyn_cast<StructType>(AggTy)) |
| return ConstantStruct::get(ST, Ops); |
| return ConstantArray::get(cast<ArrayType>(AggTy), Ops); |
| } |
| |
| if (isa<ConstantAggregateZero>(Agg)) { |
| // Insertion of constant into aggregate zero |
| // Optimize away insertion of zero. |
| if (Val->isNullValue()) |
| return Agg; |
| |
| // Otherwise break the aggregate zero into multiple zeros and do |
| // the insertion. |
| CompositeType *AggTy = cast<CompositeType>(Agg->getType()); |
| unsigned numOps; |
| if (ArrayType *AR = dyn_cast<ArrayType>(AggTy)) |
| numOps = AR->getNumElements(); |
| else |
| numOps = cast<StructType>(AggTy)->getNumElements(); |
| |
| std::vector<Constant*> Ops(numOps); |
| for (unsigned i = 0; i < numOps; ++i) { |
| Type *MemberTy = AggTy->getTypeAtIndex(i); |
| Constant *Op = |
| (Idxs[0] == i) ? |
| ConstantFoldInsertValueInstruction(Constant::getNullValue(MemberTy), |
| Val, Idxs.slice(1)) : |
| Constant::getNullValue(MemberTy); |
| Ops[i] = Op; |
| } |
| |
| if (StructType *ST = dyn_cast<StructType>(AggTy)) |
| return ConstantStruct::get(ST, Ops); |
| return ConstantArray::get(cast<ArrayType>(AggTy), Ops); |
| } |
| |
| if (isa<ConstantStruct>(Agg) || isa<ConstantArray>(Agg)) { |
| // Insertion of constant into aggregate constant. |
| std::vector<Constant*> Ops(Agg->getNumOperands()); |
| for (unsigned i = 0; i < Agg->getNumOperands(); ++i) { |
| Constant *Op = cast<Constant>(Agg->getOperand(i)); |
| if (Idxs[0] == i) |
| Op = ConstantFoldInsertValueInstruction(Op, Val, Idxs.slice(1)); |
| Ops[i] = Op; |
| } |
| |
| if (StructType* ST = dyn_cast<StructType>(Agg->getType())) |
| return ConstantStruct::get(ST, Ops); |
| return ConstantArray::get(cast<ArrayType>(Agg->getType()), Ops); |
| } |
| |
| return 0; |
| } |
| |
| |
| Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, |
| Constant *C1, Constant *C2) { |
| // No compile-time operations on this type yet. |
| if (C1->getType()->isPPC_FP128Ty()) |
| return 0; |
| |
| // Handle UndefValue up front. |
| if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) { |
| switch (Opcode) { |
| case Instruction::Xor: |
| if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) |
| // Handle undef ^ undef -> 0 special case. This is a common |
| // idiom (misuse). |
| return Constant::getNullValue(C1->getType()); |
| // Fallthrough |
| case Instruction::Add: |
| case Instruction::Sub: |
| return UndefValue::get(C1->getType()); |
| case Instruction::And: |
| if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef & undef -> undef |
| return C1; |
| return Constant::getNullValue(C1->getType()); // undef & X -> 0 |
| case Instruction::Mul: { |
| ConstantInt *CI; |
| // X * undef -> undef if X is odd or undef |
| if (((CI = dyn_cast<ConstantInt>(C1)) && CI->getValue()[0]) || |
| ((CI = dyn_cast<ConstantInt>(C2)) && CI->getValue()[0]) || |
| (isa<UndefValue>(C1) && isa<UndefValue>(C2))) |
| return UndefValue::get(C1->getType()); |
| |
| // X * undef -> 0 otherwise |
| return Constant::getNullValue(C1->getType()); |
| } |
| case Instruction::UDiv: |
| case Instruction::SDiv: |
| // undef / 1 -> undef |
| if (Opcode == Instruction::UDiv || Opcode == Instruction::SDiv) |
| if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) |
| if (CI2->isOne()) |
| return C1; |
| // FALL THROUGH |
| case Instruction::URem: |
| case Instruction::SRem: |
| if (!isa<UndefValue>(C2)) // undef / X -> 0 |
| return Constant::getNullValue(C1->getType()); |
| return C2; // X / undef -> undef |
| case Instruction::Or: // X | undef -> -1 |
| if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef | undef -> undef |
| return C1; |
| return Constant::getAllOnesValue(C1->getType()); // undef | X -> ~0 |
| case Instruction::LShr: |
| if (isa<UndefValue>(C2) && isa<UndefValue>(C1)) |
| return C1; // undef lshr undef -> undef |
| return Constant::getNullValue(C1->getType()); // X lshr undef -> 0 |
| // undef lshr X -> 0 |
| case Instruction::AShr: |
| if (!isa<UndefValue>(C2)) // undef ashr X --> all ones |
| return Constant::getAllOnesValue(C1->getType()); |
| else if (isa<UndefValue>(C1)) |
| return C1; // undef ashr undef -> undef |
| else |
| return C1; // X ashr undef --> X |
| case Instruction::Shl: |
| if (isa<UndefValue>(C2) && isa<UndefValue>(C1)) |
| return C1; // undef shl undef -> undef |
| // undef << X -> 0 or X << undef -> 0 |
| return Constant::getNullValue(C1->getType()); |
| } |
| } |
| |
| // Handle simplifications when the RHS is a constant int. |
| if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) { |
| switch (Opcode) { |
| case Instruction::Add: |
| if (CI2->equalsInt(0)) return C1; // X + 0 == X |
| break; |
| case Instruction::Sub: |
| if (CI2->equalsInt(0)) return C1; // X - 0 == X |
| break; |
| case Instruction::Mul: |
| if (CI2->equalsInt(0)) return C2; // X * 0 == 0 |
| if (CI2->equalsInt(1)) |
| return C1; // X * 1 == X |
| break; |
| case Instruction::UDiv: |
| case Instruction::SDiv: |
| if (CI2->equalsInt(1)) |
| return C1; // X / 1 == X |
| if (CI2->equalsInt(0)) |
| return UndefValue::get(CI2->getType()); // X / 0 == undef |
| break; |
| case Instruction::URem: |
| case Instruction::SRem: |
| if (CI2->equalsInt(1)) |
| return Constant::getNullValue(CI2->getType()); // X % 1 == 0 |
| if (CI2->equalsInt(0)) |
| return UndefValue::get(CI2->getType()); // X % 0 == undef |
| break; |
| case Instruction::And: |
| if (CI2->isZero()) return C2; // X & 0 == 0 |
| if (CI2->isAllOnesValue()) |
| return C1; // X & -1 == X |
| |
| if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { |
| // (zext i32 to i64) & 4294967295 -> (zext i32 to i64) |
| if (CE1->getOpcode() == Instruction::ZExt) { |
| unsigned DstWidth = CI2->getType()->getBitWidth(); |
| unsigned SrcWidth = |
| CE1->getOperand(0)->getType()->getPrimitiveSizeInBits(); |
| APInt PossiblySetBits(APInt::getLowBitsSet(DstWidth, SrcWidth)); |
| if ((PossiblySetBits & CI2->getValue()) == PossiblySetBits) |
| return C1; |
| } |
| |
| // If and'ing the address of a global with a constant, fold it. |
| if (CE1->getOpcode() == Instruction::PtrToInt && |
| isa<GlobalValue>(CE1->getOperand(0))) { |
| GlobalValue *GV = cast<GlobalValue>(CE1->getOperand(0)); |
| |
| // Functions are at least 4-byte aligned. |
| unsigned GVAlign = GV->getAlignment(); |
| if (isa<Function>(GV)) |
| GVAlign = std::max(GVAlign, 4U); |
| |
| if (GVAlign > 1) { |
| unsigned DstWidth = CI2->getType()->getBitWidth(); |
| unsigned SrcWidth = std::min(DstWidth, Log2_32(GVAlign)); |
| APInt BitsNotSet(APInt::getLowBitsSet(DstWidth, SrcWidth)); |
| |
| // If checking bits we know are clear, return zero. |
| if ((CI2->getValue() & BitsNotSet) == CI2->getValue()) |
| return Constant::getNullValue(CI2->getType()); |
| } |
| } |
| } |
| break; |
| case Instruction::Or: |
| if (CI2->equalsInt(0)) return C1; // X | 0 == X |
| if (CI2->isAllOnesValue()) |
| return C2; // X | -1 == -1 |
| break; |
| case Instruction::Xor: |
| if (CI2->equalsInt(0)) return C1; // X ^ 0 == X |
| |
| if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { |
| switch (CE1->getOpcode()) { |
| default: break; |
| case Instruction::ICmp: |
| case Instruction::FCmp: |
| // cmp pred ^ true -> cmp !pred |
| assert(CI2->equalsInt(1)); |
| CmpInst::Predicate pred = (CmpInst::Predicate)CE1->getPredicate(); |
| pred = CmpInst::getInversePredicate(pred); |
| return ConstantExpr::getCompare(pred, CE1->getOperand(0), |
| CE1->getOperand(1)); |
| } |
| } |
| break; |
| case Instruction::AShr: |
| // ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2 |
| if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) |
| if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero. |
| return ConstantExpr::getLShr(C1, C2); |
| break; |
| } |
| } else if (isa<ConstantInt>(C1)) { |
| // If C1 is a ConstantInt and C2 is not, swap the operands. |
| if (Instruction::isCommutative(Opcode)) |
| return ConstantExpr::get(Opcode, C2, C1); |
| } |
| |
| // At this point we know neither constant is an UndefValue. |
| if (ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) { |
| if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) { |
| using namespace APIntOps; |
| const APInt &C1V = CI1->getValue(); |
| const APInt &C2V = CI2->getValue(); |
| switch (Opcode) { |
| default: |
| break; |
| case Instruction::Add: |
| return ConstantInt::get(CI1->getContext(), C1V + C2V); |
| case Instruction::Sub: |
| return ConstantInt::get(CI1->getContext(), C1V - C2V); |
| case Instruction::Mul: |
| return ConstantInt::get(CI1->getContext(), C1V * C2V); |
| case Instruction::UDiv: |
| assert(!CI2->isNullValue() && "Div by zero handled above"); |
| return ConstantInt::get(CI1->getContext(), C1V.udiv(C2V)); |
| case Instruction::SDiv: |
| assert(!CI2->isNullValue() && "Div by zero handled above"); |
| if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) |
| return UndefValue::get(CI1->getType()); // MIN_INT / -1 -> undef |
| return ConstantInt::get(CI1->getContext(), C1V.sdiv(C2V)); |
| case Instruction::URem: |
| assert(!CI2->isNullValue() && "Div by zero handled above"); |
| return ConstantInt::get(CI1->getContext(), C1V.urem(C2V)); |
| case Instruction::SRem: |
| assert(!CI2->isNullValue() && "Div by zero handled above"); |
| if (C2V.isAllOnesValue() && C1V.isMinSignedValue()) |
| return UndefValue::get(CI1->getType()); // MIN_INT % -1 -> undef |
| return ConstantInt::get(CI1->getContext(), C1V.srem(C2V)); |
| case Instruction::And: |
| return ConstantInt::get(CI1->getContext(), C1V & C2V); |
| case Instruction::Or: |
| return ConstantInt::get(CI1->getContext(), C1V | C2V); |
| case Instruction::Xor: |
| return ConstantInt::get(CI1->getContext(), C1V ^ C2V); |
| case Instruction::Shl: { |
| uint32_t shiftAmt = C2V.getZExtValue(); |
| if (shiftAmt < C1V.getBitWidth()) |
| return ConstantInt::get(CI1->getContext(), C1V.shl(shiftAmt)); |
| else |
| return UndefValue::get(C1->getType()); // too big shift is undef |
| } |
| case Instruction::LShr: { |
| uint32_t shiftAmt = C2V.getZExtValue(); |
| if (shiftAmt < C1V.getBitWidth()) |
| return ConstantInt::get(CI1->getContext(), C1V.lshr(shiftAmt)); |
| else |
| return UndefValue::get(C1->getType()); // too big shift is undef |
| } |
| case Instruction::AShr: { |
| uint32_t shiftAmt = C2V.getZExtValue(); |
| if (shiftAmt < C1V.getBitWidth()) |
| return ConstantInt::get(CI1->getContext(), C1V.ashr(shiftAmt)); |
| else |
| return UndefValue::get(C1->getType()); // too big shift is undef |
| } |
| } |
| } |
| |
| switch (Opcode) { |
| case Instruction::SDiv: |
| case Instruction::UDiv: |
| case Instruction::URem: |
| case Instruction::SRem: |
| case Instruction::LShr: |
| case Instruction::AShr: |
| case Instruction::Shl: |
| if (CI1->equalsInt(0)) return C1; |
| break; |
| default: |
| break; |
| } |
| } else if (ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) { |
| if (ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) { |
| APFloat C1V = CFP1->getValueAPF(); |
| APFloat C2V = CFP2->getValueAPF(); |
| APFloat C3V = C1V; // copy for modification |
| switch (Opcode) { |
| default: |
| break; |
| case Instruction::FAdd: |
| (void)C3V.add(C2V, APFloat::rmNearestTiesToEven); |
| return ConstantFP::get(C1->getContext(), C3V); |
| case Instruction::FSub: |
| (void)C3V.subtract(C2V, APFloat::rmNearestTiesToEven); |
| return ConstantFP::get(C1->getContext(), C3V); |
| case Instruction::FMul: |
| (void)C3V.multiply(C2V, APFloat::rmNearestTiesToEven); |
| return ConstantFP::get(C1->getContext(), C3V); |
| case Instruction::FDiv: |
| (void)C3V.divide(C2V, APFloat::rmNearestTiesToEven); |
| return ConstantFP::get(C1->getContext(), C3V); |
| case Instruction::FRem: |
| (void)C3V.mod(C2V, APFloat::rmNearestTiesToEven); |
| return ConstantFP::get(C1->getContext(), C3V); |
| } |
| } |
| } else if (VectorType *VTy = dyn_cast<VectorType>(C1->getType())) { |
| ConstantVector *CP1 = dyn_cast<ConstantVector>(C1); |
| ConstantVector *CP2 = dyn_cast<ConstantVector>(C2); |
| if ((CP1 != NULL || isa<ConstantAggregateZero>(C1)) && |
| (CP2 != NULL || isa<ConstantAggregateZero>(C2))) { |
| std::vector<Constant*> Res; |
| Type* EltTy = VTy->getElementType(); |
| Constant *C1 = 0; |
| Constant *C2 = 0; |
| switch (Opcode) { |
| default: |
| break; |
| case Instruction::Add: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getAdd(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::FAdd: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getFAdd(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::Sub: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getSub(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::FSub: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getFSub(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::Mul: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getMul(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::FMul: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getFMul(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::UDiv: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getUDiv(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::SDiv: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getSDiv(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::FDiv: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getFDiv(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::URem: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getURem(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::SRem: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getSRem(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::FRem: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getFRem(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::And: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getAnd(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::Or: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getOr(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::Xor: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getXor(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::LShr: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getLShr(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::AShr: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getAShr(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| case Instruction::Shl: |
| for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { |
| C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy); |
| C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy); |
| Res.push_back(ConstantExpr::getShl(C1, C2)); |
| } |
| return ConstantVector::get(Res); |
| } |
| } |
| } |
| |
| if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { |
| // There are many possible foldings we could do here. We should probably |
| // at least fold add of a pointer with an integer into the appropriate |
| // getelementptr. This will improve alias analysis a bit. |
| |
| // Given ((a + b) + c), if (b + c) folds to something interesting, return |
| // (a + (b + c)). |
| if (Instruction::isAssociative(Opcode) && CE1->getOpcode() == Opcode) { |
| Constant *T = ConstantExpr::get(Opcode, CE1->getOperand(1), C2); |
| if (!isa<ConstantExpr>(T) || cast<ConstantExpr>(T)->getOpcode() != Opcode) |
| return ConstantExpr::get(Opcode, CE1->getOperand(0), T); |
| } |
| } else if (isa<ConstantExpr>(C2)) { |
| // If C2 is a constant expr and C1 isn't, flop them around and fold the |
| // other way if possible. |
| if (Instruction::isCommutative(Opcode)) |
| return ConstantFoldBinaryInstruction(Opcode, C2, C1); |
| } |
| |
| // i1 can be simplified in many cases. |
| if (C1->getType()->isIntegerTy(1)) { |
| switch (Opcode) { |
| case Instruction::Add: |
| case Instruction::Sub: |
| return ConstantExpr::getXor(C1, C2); |
| case Instruction::Mul: |
| return ConstantExpr::getAnd(C1, C2); |
| case Instruction::Shl: |
| case Instruction::LShr: |
| case Instruction::AShr: |
| // We can assume that C2 == 0. If it were one the result would be |
| // undefined because the shift value is as large as the bitwidth. |
| return C1; |
| case Instruction::SDiv: |
| case Instruction::UDiv: |
| // We can assume that C2 == 1. If it were zero the result would be |
| // undefined through division by zero. |
| return C1; |
| case Instruction::URem: |
| case Instruction::SRem: |
| // We can assume that C2 == 1. If it were zero the result would be |
| // undefined through division by zero. |
| return ConstantInt::getFalse(C1->getContext()); |
| default: |
| break; |
| } |
| } |
| |
| // We don't know how to fold this. |
| return 0; |
| } |
| |
| /// isZeroSizedType - This type is zero sized if its an array or structure of |
| /// zero sized types. The only leaf zero sized type is an empty structure. |
| static bool isMaybeZeroSizedType(Type *Ty) { |
| if (StructType *STy = dyn_cast<StructType>(Ty)) { |
| if (STy->isOpaque()) return true; // Can't say. |
| |
| // If all of elements have zero size, this does too. |
| for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) |
| if (!isMaybeZeroSizedType(STy->getElementType(i))) return false; |
| return true; |
| |
| } else if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { |
| return isMaybeZeroSizedType(ATy->getElementType()); |
| } |
| return false; |
| } |
| |
| /// IdxCompare - Compare the two constants as though they were getelementptr |
| /// indices. This allows coersion of the types to be the same thing. |
| /// |
| /// If the two constants are the "same" (after coersion), return 0. If the |
| /// first is less than the second, return -1, if the second is less than the |
| /// first, return 1. If the constants are not integral, return -2. |
| /// |
| static int IdxCompare(Constant *C1, Constant *C2, Type *ElTy) { |
| if (C1 == C2) return 0; |
| |
| // Ok, we found a different index. If they are not ConstantInt, we can't do |
| // anything with them. |
| if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2)) |
| return -2; // don't know! |
| |
| // Ok, we have two differing integer indices. Sign extend them to be the same |
| // type. Long is always big enough, so we use it. |
| if (!C1->getType()->isIntegerTy(64)) |
| C1 = ConstantExpr::getSExt(C1, Type::getInt64Ty(C1->getContext())); |
| |
| if (!C2->getType()->isIntegerTy(64)) |
| C2 = ConstantExpr::getSExt(C2, Type::getInt64Ty(C1->getContext())); |
| |
| if (C1 == C2) return 0; // They are equal |
| |
| // If the type being indexed over is really just a zero sized type, there is |
| // no pointer difference being made here. |
| if (isMaybeZeroSizedType(ElTy)) |
| return -2; // dunno. |
| |
| // If they are really different, now that they are the same type, then we |
| // found a difference! |
| if (cast<ConstantInt>(C1)->getSExtValue() < |
| cast<ConstantInt>(C2)->getSExtValue()) |
| return -1; |
| else |
| return 1; |
| } |
| |
| /// evaluateFCmpRelation - This function determines if there is anything we can |
| /// decide about the two constants provided. This doesn't need to handle simple |
| /// things like ConstantFP comparisons, but should instead handle ConstantExprs. |
| /// If we can determine that the two constants have a particular relation to |
| /// each other, we should return the corresponding FCmpInst predicate, |
| /// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in |
| /// ConstantFoldCompareInstruction. |
| /// |
| /// To simplify this code we canonicalize the relation so that the first |
| /// operand is always the most "complex" of the two. We consider ConstantFP |
| /// to be the simplest, and ConstantExprs to be the most complex. |
| static FCmpInst::Predicate evaluateFCmpRelation(Constant *V1, Constant *V2) { |
| assert(V1->getType() == V2->getType() && |
| "Cannot compare values of different types!"); |
| |
| // No compile-time operations on this type yet. |
| if (V1->getType()->isPPC_FP128Ty()) |
| return FCmpInst::BAD_FCMP_PREDICATE; |
| |
| // Handle degenerate case quickly |
| if (V1 == V2) return FCmpInst::FCMP_OEQ; |
| |
| if (!isa<ConstantExpr>(V1)) { |
| if (!isa<ConstantExpr>(V2)) { |
| // We distilled thisUse the standard constant folder for a few cases |
| ConstantInt *R = 0; |
| R = dyn_cast<ConstantInt>( |
| ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, V1, V2)); |
| if (R && !R->isZero()) |
| return FCmpInst::FCMP_OEQ; |
| R = dyn_cast<ConstantInt>( |
| ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, V1, V2)); |
| if (R && !R->isZero()) |
| return FCmpInst::FCMP_OLT; |
| R = dyn_cast<ConstantInt>( |
| ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, V1, V2)); |
| if (R && !R->isZero()) |
| return FCmpInst::FCMP_OGT; |
| |
| // Nothing more we can do |
| return FCmpInst::BAD_FCMP_PREDICATE; |
| } |
| |
| // If the first operand is simple and second is ConstantExpr, swap operands. |
| FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1); |
| if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE) |
| return FCmpInst::getSwappedPredicate(SwappedRelation); |
| } else { |
| // Ok, the LHS is known to be a constantexpr. The RHS can be any of a |
| // constantexpr or a simple constant. |
| ConstantExpr *CE1 = cast<ConstantExpr>(V1); |
| switch (CE1->getOpcode()) { |
| case Instruction::FPTrunc: |
| case Instruction::FPExt: |
| case Instruction::UIToFP: |
| case Instruction::SIToFP: |
| // We might be able to do something with these but we don't right now. |
| break; |
| default: |
| break; |
| } |
| } |
| // There are MANY other foldings that we could perform here. They will |
| // probably be added on demand, as they seem needed. |
| return FCmpInst::BAD_FCMP_PREDICATE; |
| } |
| |
| /// evaluateICmpRelation - This function determines if there is anything we can |
| /// decide about the two constants provided. This doesn't need to handle simple |
| /// things like integer comparisons, but should instead handle ConstantExprs |
| /// and GlobalValues. If we can determine that the two constants have a |
| /// particular relation to each other, we should return the corresponding ICmp |
| /// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE. |
| /// |
| /// To simplify this code we canonicalize the relation so that the first |
| /// operand is always the most "complex" of the two. We consider simple |
| /// constants (like ConstantInt) to be the simplest, followed by |
| /// GlobalValues, followed by ConstantExpr's (the most complex). |
| /// |
| static ICmpInst::Predicate evaluateICmpRelation(Constant *V1, Constant *V2, |
| bool isSigned) { |
| assert(V1->getType() == V2->getType() && |
| "Cannot compare different types of values!"); |
| if (V1 == V2) return ICmpInst::ICMP_EQ; |
| |
| if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1) && |
| !isa<BlockAddress>(V1)) { |
| if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2) && |
| !isa<BlockAddress>(V2)) { |
| // We distilled this down to a simple case, use the standard constant |
| // folder. |
| ConstantInt *R = 0; |
| ICmpInst::Predicate pred = ICmpInst::ICMP_EQ; |
| R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); |
| if (R && !R->isZero()) |
| return pred; |
| pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; |
| R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); |
| if (R && !R->isZero()) |
| return pred; |
| pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; |
| R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); |
| if (R && !R->isZero()) |
| return pred; |
| |
| // If we couldn't figure it out, bail. |
| return ICmpInst::BAD_ICMP_PREDICATE; |
| } |
| |
| // If the first operand is simple, swap operands. |
| ICmpInst::Predicate SwappedRelation = |
| evaluateICmpRelation(V2, V1, isSigned); |
| if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) |
| return ICmpInst::getSwappedPredicate(SwappedRelation); |
| |
| } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(V1)) { |
| if (isa<ConstantExpr>(V2)) { // Swap as necessary. |
| ICmpInst::Predicate SwappedRelation = |
| evaluateICmpRelation(V2, V1, isSigned); |
| if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) |
| return ICmpInst::getSwappedPredicate(SwappedRelation); |
| return ICmpInst::BAD_ICMP_PREDICATE; |
| } |
| |
| // Now we know that the RHS is a GlobalValue, BlockAddress or simple |
| // constant (which, since the types must match, means that it's a |
| // ConstantPointerNull). |
| if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) { |
| // Don't try to decide equality of aliases. |
| if (!isa<GlobalAlias>(GV) && !isa<GlobalAlias>(GV2)) |
| if (!GV->hasExternalWeakLinkage() || !GV2->hasExternalWeakLinkage()) |
| return ICmpInst::ICMP_NE; |
| } else if (isa<BlockAddress>(V2)) { |
| return ICmpInst::ICMP_NE; // Globals never equal labels. |
| } else { |
| assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!"); |
| // GlobalVals can never be null unless they have external weak linkage. |
| // We don't try to evaluate aliases here. |
| if (!GV->hasExternalWeakLinkage() && !isa<GlobalAlias>(GV)) |
| return ICmpInst::ICMP_NE; |
| } |
| } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(V1)) { |
| if (isa<ConstantExpr>(V2)) { // Swap as necessary. |
| ICmpInst::Predicate SwappedRelation = |
| evaluateICmpRelation(V2, V1, isSigned); |
| if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) |
| return ICmpInst::getSwappedPredicate(SwappedRelation); |
| return ICmpInst::BAD_ICMP_PREDICATE; |
| } |
| |
| // Now we know that the RHS is a GlobalValue, BlockAddress or simple |
| // constant (which, since the types must match, means that it is a |
| // ConstantPointerNull). |
| if (const BlockAddress *BA2 = dyn_cast<BlockAddress>(V2)) { |
| // Block address in another function can't equal this one, but block |
| // addresses in the current function might be the same if blocks are |
| // empty. |
| if (BA2->getFunction() != BA->getFunction()) |
| return ICmpInst::ICMP_NE; |
| } else { |
| // Block addresses aren't null, don't equal the address of globals. |
| assert((isa<ConstantPointerNull>(V2) || isa<GlobalValue>(V2)) && |
| "Canonicalization guarantee!"); |
| return ICmpInst::ICMP_NE; |
| } |
| } else { |
| // Ok, the LHS is known to be a constantexpr. The RHS can be any of a |
| // constantexpr, a global, block address, or a simple constant. |
| ConstantExpr *CE1 = cast<ConstantExpr>(V1); |
| Constant *CE1Op0 = CE1->getOperand(0); |
| |
| switch (CE1->getOpcode()) { |
| case Instruction::Trunc: |
| case Instruction::FPTrunc: |
| case Instruction::FPExt: |
| case Instruction::FPToUI: |
| case Instruction::FPToSI: |
| break; // We can't evaluate floating point casts or truncations. |
| |
| case Instruction::UIToFP: |
| case Instruction::SIToFP: |
| case Instruction::BitCast: |
| case Instruction::ZExt: |
| case Instruction::SExt: |
| // If the cast is not actually changing bits, and the second operand is a |
| // null pointer, do the comparison with the pre-casted value. |
| if (V2->isNullValue() && |
| (CE1->getType()->isPointerTy() || CE1->getType()->isIntegerTy())) { |
| if (CE1->getOpcode() == Instruction::ZExt) isSigned = false; |
| if (CE1->getOpcode() == Instruction::SExt) isSigned = true; |
| return evaluateICmpRelation(CE1Op0, |
| Constant::getNullValue(CE1Op0->getType()), |
| isSigned); |
| } |
| break; |
| |
| case Instruction::GetElementPtr: |
| // Ok, since this is a getelementptr, we know that the constant has a |
| // pointer type. Check the various cases. |
| if (isa<ConstantPointerNull>(V2)) { |
| // If we are comparing a GEP to a null pointer, check to see if the base |
| // of the GEP equals the null pointer. |
| if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) { |
| if (GV->hasExternalWeakLinkage()) |
| // Weak linkage GVals could be zero or not. We're comparing that |
| // to null pointer so its greater-or-equal |
| return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; |
| else |
| // If its not weak linkage, the GVal must have a non-zero address |
| // so the result is greater-than |
| return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; |
| } else if (isa<ConstantPointerNull>(CE1Op0)) { |
| // If we are indexing from a null pointer, check to see if we have any |
| // non-zero indices. |
| for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i) |
| if (!CE1->getOperand(i)->isNullValue()) |
| // Offsetting from null, must not be equal. |
| return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; |
| // Only zero indexes from null, must still be zero. |
| return ICmpInst::ICMP_EQ; |
| } |
| // Otherwise, we can't really say if the first operand is null or not. |
| } else if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) { |
| if (isa<ConstantPointerNull>(CE1Op0)) { |
| if (GV2->hasExternalWeakLinkage()) |
| // Weak linkage GVals could be zero or not. We're comparing it to |
| // a null pointer, so its less-or-equal |
| return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; |
| else |
| // If its not weak linkage, the GVal must have a non-zero address |
| // so the result is less-than |
| return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; |
| } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) { |
| if (GV == GV2) { |
| // If this is a getelementptr of the same global, then it must be |
| // different. Because the types must match, the getelementptr could |
| // only have at most one index, and because we fold getelementptr's |
| // with a single zero index, it must be nonzero. |
| assert(CE1->getNumOperands() == 2 && |
| !CE1->getOperand(1)->isNullValue() && |
| "Surprising getelementptr!"); |
| return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; |
| } else { |
| // If they are different globals, we don't know what the value is, |
| // but they can't be equal. |
| return ICmpInst::ICMP_NE; |
| } |
| } |
| } else { |
| ConstantExpr *CE2 = cast<ConstantExpr>(V2); |
| Constant *CE2Op0 = CE2->getOperand(0); |
| |
| // There are MANY other foldings that we could perform here. They will |
| // probably be added on demand, as they seem needed. |
| switch (CE2->getOpcode()) { |
| default: break; |
| case Instruction::GetElementPtr: |
| // By far the most common case to handle is when the base pointers are |
| // obviously to the same or different globals. |
| if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) { |
| if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal |
| return ICmpInst::ICMP_NE; |
| // Ok, we know that both getelementptr instructions are based on the |
| // same global. From this, we can precisely determine the relative |
| // ordering of the resultant pointers. |
| unsigned i = 1; |
| |
| // The logic below assumes that the result of the comparison |
| // can be determined by finding the first index that differs. |
| // This doesn't work if there is over-indexing in any |
| // subsequent indices, so check for that case first. |
| if (!CE1->isGEPWithNoNotionalOverIndexing() || |
| !CE2->isGEPWithNoNotionalOverIndexing()) |
| return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. |
| |
| // Compare all of the operands the GEP's have in common. |
| gep_type_iterator GTI = gep_type_begin(CE1); |
| for (;i != CE1->getNumOperands() && i != CE2->getNumOperands(); |
| ++i, ++GTI) |
| switch (IdxCompare(CE1->getOperand(i), |
| CE2->getOperand(i), GTI.getIndexedType())) { |
| case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT; |
| case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT; |
| case -2: return ICmpInst::BAD_ICMP_PREDICATE; |
| } |
| |
| // Ok, we ran out of things they have in common. If any leftovers |
| // are non-zero then we have a difference, otherwise we are equal. |
| for (; i < CE1->getNumOperands(); ++i) |
| if (!CE1->getOperand(i)->isNullValue()) { |
| if (isa<ConstantInt>(CE1->getOperand(i))) |
| return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; |
| else |
| return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. |
| } |
| |
| for (; i < CE2->getNumOperands(); ++i) |
| if (!CE2->getOperand(i)->isNullValue()) { |
| if (isa<ConstantInt>(CE2->getOperand(i))) |
| return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; |
| else |
| return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal. |
| } |
| return ICmpInst::ICMP_EQ; |
| } |
| } |
| } |
| default: |
| break; |
| } |
| } |
| |
| return ICmpInst::BAD_ICMP_PREDICATE; |
| } |
| |
| Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred, |
| Constant *C1, Constant *C2) { |
| Type *ResultTy; |
| if (VectorType *VT = dyn_cast<VectorType>(C1->getType())) |
| ResultTy = VectorType::get(Type::getInt1Ty(C1->getContext()), |
| VT->getNumElements()); |
| else |
| ResultTy = Type::getInt1Ty(C1->getContext()); |
| |
| // Fold FCMP_FALSE/FCMP_TRUE unconditionally. |
| if (pred == FCmpInst::FCMP_FALSE) |
| return Constant::getNullValue(ResultTy); |
| |
| if (pred == FCmpInst::FCMP_TRUE) |
| return Constant::getAllOnesValue(ResultTy); |
| |
| // Handle some degenerate cases first |
| if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) { |
| // For EQ and NE, we can always pick a value for the undef to make the |
| // predicate pass or fail, so we can return undef. |
| // Also, if both operands are undef, we can return undef. |
| if (ICmpInst::isEquality(ICmpInst::Predicate(pred)) || |
| (isa<UndefValue>(C1) && isa<UndefValue>(C2))) |
| return UndefValue::get(ResultTy); |
| // Otherwise, pick the same value as the non-undef operand, and fold |
| // it to true or false. |
| return ConstantInt::get(ResultTy, CmpInst::isTrueWhenEqual(pred)); |
| } |
| |
| // No compile-time operations on this type yet. |
| if (C1->getType()->isPPC_FP128Ty()) |
| return 0; |
| |
| // icmp eq/ne(null,GV) -> false/true |
| if (C1->isNullValue()) { |
| if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2)) |
| // Don't try to evaluate aliases. External weak GV can be null. |
| if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) { |
| if (pred == ICmpInst::ICMP_EQ) |
| return ConstantInt::getFalse(C1->getContext()); |
| else if (pred == ICmpInst::ICMP_NE) |
| return ConstantInt::getTrue(C1->getContext()); |
| } |
| // icmp eq/ne(GV,null) -> false/true |
| } else if (C2->isNullValue()) { |
| if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1)) |
| // Don't try to evaluate aliases. External weak GV can be null. |
| if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) { |
| if (pred == ICmpInst::ICMP_EQ) |
| return ConstantInt::getFalse(C1->getContext()); |
| else if (pred == ICmpInst::ICMP_NE) |
| return ConstantInt::getTrue(C1->getContext()); |
| } |
| } |
| |
| // If the comparison is a comparison between two i1's, simplify it. |
| if (C1->getType()->isIntegerTy(1)) { |
| switch(pred) { |
| case ICmpInst::ICMP_EQ: |
| if (isa<ConstantInt>(C2)) |
| return ConstantExpr::getXor(C1, ConstantExpr::getNot(C2)); |
| return ConstantExpr::getXor(ConstantExpr::getNot(C1), C2); |
| case ICmpInst::ICMP_NE: |
| return ConstantExpr::getXor(C1, C2); |
| default: |
| break; |
| } |
| } |
| |
| if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) { |
| APInt V1 = cast<ConstantInt>(C1)->getValue(); |
| APInt V2 = cast<ConstantInt>(C2)->getValue(); |
| switch (pred) { |
| default: llvm_unreachable("Invalid ICmp Predicate"); return 0; |
| case ICmpInst::ICMP_EQ: return ConstantInt::get(ResultTy, V1 == V2); |
| case ICmpInst::ICMP_NE: return ConstantInt::get(ResultTy, V1 != V2); |
| case ICmpInst::ICMP_SLT: return ConstantInt::get(ResultTy, V1.slt(V2)); |
| case ICmpInst::ICMP_SGT: return ConstantInt::get(ResultTy, V1.sgt(V2)); |
| case ICmpInst::ICMP_SLE: return ConstantInt::get(ResultTy, V1.sle(V2)); |
| case ICmpInst::ICMP_SGE: return ConstantInt::get(ResultTy, V1.sge(V2)); |
| case ICmpInst::ICMP_ULT: return ConstantInt::get(ResultTy, V1.ult(V2)); |
| case ICmpInst::ICMP_UGT: return ConstantInt::get(ResultTy, V1.ugt(V2)); |
| case ICmpInst::ICMP_ULE: return ConstantInt::get(ResultTy, V1.ule(V2)); |
| case ICmpInst::ICMP_UGE: return ConstantInt::get(ResultTy, V1.uge(V2)); |
| } |
| } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) { |
| APFloat C1V = cast<ConstantFP>(C1)->getValueAPF(); |
| APFloat C2V = cast<ConstantFP>(C2)->getValueAPF(); |
| APFloat::cmpResult R = C1V.compare(C2V); |
| switch (pred) { |
| default: llvm_unreachable("Invalid FCmp Predicate"); return 0; |
| case FCmpInst::FCMP_FALSE: return Constant::getNullValue(ResultTy); |
| case FCmpInst::FCMP_TRUE: return Constant::getAllOnesValue(ResultTy); |
| case FCmpInst::FCMP_UNO: |
| return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered); |
| case FCmpInst::FCMP_ORD: |
| return ConstantInt::get(ResultTy, R!=APFloat::cmpUnordered); |
| case FCmpInst::FCMP_UEQ: |
| return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered || |
| R==APFloat::cmpEqual); |
| case FCmpInst::FCMP_OEQ: |
| return ConstantInt::get(ResultTy, R==APFloat::cmpEqual); |
| case FCmpInst::FCMP_UNE: |
| return ConstantInt::get(ResultTy, R!=APFloat::cmpEqual); |
| case FCmpInst::FCMP_ONE: |
| return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan || |
| R==APFloat::cmpGreaterThan); |
| case FCmpInst::FCMP_ULT: |
| return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered || |
| R==APFloat::cmpLessThan); |
| case FCmpInst::FCMP_OLT: |
| return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan); |
| case FCmpInst::FCMP_UGT: |
| return ConstantInt::get(ResultTy, R==APFloat::cmpUnordered || |
| R==APFloat::cmpGreaterThan); |
| case FCmpInst::FCMP_OGT: |
| return ConstantInt::get(ResultTy, R==APFloat::cmpGreaterThan); |
| case FCmpInst::FCMP_ULE: |
| return ConstantInt::get(ResultTy, R!=APFloat::cmpGreaterThan); |
| case FCmpInst::FCMP_OLE: |
| return ConstantInt::get(ResultTy, R==APFloat::cmpLessThan || |
| R==APFloat::cmpEqual); |
| case FCmpInst::FCMP_UGE: |
| return ConstantInt::get(ResultTy, R!=APFloat::cmpLessThan); |
| case FCmpInst::FCMP_OGE: |
| return ConstantInt::get(ResultTy, R==APFloat::cmpGreaterThan || |
| R==APFloat::cmpEqual); |
| } |
| } else if (C1->getType()->isVectorTy()) { |
| SmallVector<Constant*, 16> C1Elts, C2Elts; |
| C1->getVectorElements(C1Elts); |
| C2->getVectorElements(C2Elts); |
| if (C1Elts.empty() || C2Elts.empty()) |
| return 0; |
| |
| // If we can constant fold the comparison of each element, constant fold |
| // the whole vector comparison. |
| SmallVector<Constant*, 4> ResElts; |
| // Compare the elements, producing an i1 result or constant expr. |
| for (unsigned i = 0, e = C1Elts.size(); i != e; ++i) |
| ResElts.push_back(ConstantExpr::getCompare(pred, C1Elts[i], C2Elts[i])); |
| |
| return ConstantVector::get(ResElts); |
| } |
| |
| if (C1->getType()->isFloatingPointTy()) { |
| int Result = -1; // -1 = unknown, 0 = known false, 1 = known true. |
| switch (evaluateFCmpRelation(C1, C2)) { |
| default: llvm_unreachable("Unknown relation!"); |
| case FCmpInst::FCMP_UNO: |
| case FCmpInst::FCMP_ORD: |
| case FCmpInst::FCMP_UEQ: |
| case FCmpInst::FCMP_UNE: |
| case FCmpInst::FCMP_ULT: |
| case FCmpInst::FCMP_UGT: |
| case FCmpInst::FCMP_ULE: |
| case FCmpInst::FCMP_UGE: |
| case FCmpInst::FCMP_TRUE: |
| case FCmpInst::FCMP_FALSE: |
| case FCmpInst::BAD_FCMP_PREDICATE: |
| break; // Couldn't determine anything about these constants. |
| case FCmpInst::FCMP_OEQ: // We know that C1 == C2 |
| Result = (pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ || |
| pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE || |
| pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); |
| break; |
| case FCmpInst::FCMP_OLT: // We know that C1 < C2 |
| Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || |
| pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT || |
| pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE); |
| break; |
| case FCmpInst::FCMP_OGT: // We know that C1 > C2 |
| Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE || |
| pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT || |
| pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE); |
| break; |
| case FCmpInst::FCMP_OLE: // We know that C1 <= C2 |
| // We can only partially decide this relation. |
| if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) |
| Result = 0; |
| else if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) |
| Result = 1; |
| break; |
| case FCmpInst::FCMP_OGE: // We known that C1 >= C2 |
| // We can only partially decide this relation. |
| if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT) |
| Result = 0; |
| else if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT) |
| Result = 1; |
| break; |
| case FCmpInst::FCMP_ONE: // We know that C1 != C2 |
| // We can only partially decide this relation. |
| if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ) |
| Result = 0; |
| else if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE) |
| Result = 1; |
| break; |
| } |
| |
| // If we evaluated the result, return it now. |
| if (Result != -1) |
| return ConstantInt::get(ResultTy, Result); |
| |
| } else { |
| // Evaluate the relation between the two constants, per the predicate. |
| int Result = -1; // -1 = unknown, 0 = known false, 1 = known true. |
| switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) { |
| default: llvm_unreachable("Unknown relational!"); |
| case ICmpInst::BAD_ICMP_PREDICATE: |
| break; // Couldn't determine anything about these constants. |
| case ICmpInst::ICMP_EQ: // We know the constants are equal! |
| // If we know the constants are equal, we can decide the result of this |
| // computation precisely. |
| Result = ICmpInst::isTrueWhenEqual((ICmpInst::Predicate)pred); |
| break; |
| case ICmpInst::ICMP_ULT: |
| switch (pred) { |
| case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_ULE: |
| Result = 1; break; |
| case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_UGE: |
| Result = 0; break; |
| } |
| break; |
| case ICmpInst::ICMP_SLT: |
| switch (pred) { |
| case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SLE: |
| Result = 1; break; |
| case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SGE: |
| Result = 0; break; |
| } |
| break; |
| case ICmpInst::ICMP_UGT: |
| switch (pred) { |
| case ICmpInst::ICMP_UGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_UGE: |
| Result = 1; break; |
| case ICmpInst::ICMP_ULT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_ULE: |
| Result = 0; break; |
| } |
| break; |
| case ICmpInst::ICMP_SGT: |
| switch (pred) { |
| case ICmpInst::ICMP_SGT: case ICmpInst::ICMP_NE: case ICmpInst::ICMP_SGE: |
| Result = 1; break; |
| case ICmpInst::ICMP_SLT: case ICmpInst::ICMP_EQ: case ICmpInst::ICMP_SLE: |
| Result = 0; break; |
| } |
| break; |
| case ICmpInst::ICMP_ULE: |
| if (pred == ICmpInst::ICMP_UGT) Result = 0; |
| if (pred == ICmpInst::ICMP_ULT || pred == ICmpInst::ICMP_ULE) Result = 1; |
| break; |
| case ICmpInst::ICMP_SLE: |
| if (pred == ICmpInst::ICMP_SGT) Result = 0; |
| if (pred == ICmpInst::ICMP_SLT || pred == ICmpInst::ICMP_SLE) Result = 1; |
| break; |
| case ICmpInst::ICMP_UGE: |
| if (pred == ICmpInst::ICMP_ULT) Result = 0; |
| if (pred == ICmpInst::ICMP_UGT || pred == ICmpInst::ICMP_UGE) Result = 1; |
| break; |
| case ICmpInst::ICMP_SGE: |
| if (pred == ICmpInst::ICMP_SLT) Result = 0; |
| if (pred == ICmpInst::ICMP_SGT || pred == ICmpInst::ICMP_SGE) Result = 1; |
| break; |
| case ICmpInst::ICMP_NE: |
| if (pred == ICmpInst::ICMP_EQ) Result = 0; |
| if (pred == ICmpInst::ICMP_NE) Result = 1; |
| break; |
| } |
| |
| // If we evaluated the result, return it now. |
| if (Result != -1) |
| return ConstantInt::get(ResultTy, Result); |
| |
| // If the right hand side is a bitcast, try using its inverse to simplify |
| // it by moving it to the left hand side. We can't do this if it would turn |
| // a vector compare into a scalar compare or visa versa. |
| if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(C2)) { |
| Constant *CE2Op0 = CE2->getOperand(0); |
| if (CE2->getOpcode() == Instruction::BitCast && |
| CE2->getType()->isVectorTy() == CE2Op0->getType()->isVectorTy()) { |
| Constant *Inverse = ConstantExpr::getBitCast(C1, CE2Op0->getType()); |
| return ConstantExpr::getICmp(pred, Inverse, CE2Op0); |
| } |
| } |
| |
| // If the left hand side is an extension, try eliminating it. |
| if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { |
| if ((CE1->getOpcode() == Instruction::SExt && ICmpInst::isSigned(pred)) || |
| (CE1->getOpcode() == Instruction::ZExt && !ICmpInst::isSigned(pred))){ |
| Constant *CE1Op0 = CE1->getOperand(0); |
| Constant *CE1Inverse = ConstantExpr::getTrunc(CE1, CE1Op0->getType()); |
| if (CE1Inverse == CE1Op0) { |
| // Check whether we can safely truncate the right hand side. |
| Constant *C2Inverse = ConstantExpr::getTrunc(C2, CE1Op0->getType()); |
| if (ConstantExpr::getZExt(C2Inverse, C2->getType()) == C2) { |
| return ConstantExpr::getICmp(pred, CE1Inverse, C2Inverse); |
| } |
| } |
| } |
| } |
| |
| if ((!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) || |
| (C1->isNullValue() && !C2->isNullValue())) { |
| // If C2 is a constant expr and C1 isn't, flip them around and fold the |
| // other way if possible. |
| // Also, if C1 is null and C2 isn't, flip them around. |
| pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred); |
| return ConstantExpr::getICmp(pred, C2, C1); |
| } |
| } |
| return 0; |
| } |
| |
| /// isInBoundsIndices - Test whether the given sequence of *normalized* indices |
| /// is "inbounds". |
| template<typename IndexTy> |
| static bool isInBoundsIndices(IndexTy const *Idxs, size_t NumIdx) { |
| // No indices means nothing that could be out of bounds. |
| if (NumIdx == 0) return true; |
| |
| // If the first index is zero, it's in bounds. |
| if (cast<Constant>(Idxs[0])->isNullValue()) return true; |
| |
| // If the first index is one and all the rest are zero, it's in bounds, |
| // by the one-past-the-end rule. |
| if (!cast<ConstantInt>(Idxs[0])->isOne()) |
| return false; |
| for (unsigned i = 1, e = NumIdx; i != e; ++i) |
| if (!cast<Constant>(Idxs[i])->isNullValue()) |
| return false; |
| return true; |
| } |
| |
| template<typename IndexTy> |
| static Constant *ConstantFoldGetElementPtrImpl(Constant *C, |
| bool inBounds, |
| ArrayRef<IndexTy> Idxs) { |
| if (Idxs.empty()) return C; |
| Constant *Idx0 = cast<Constant>(Idxs[0]); |
| if ((Idxs.size() == 1 && Idx0->isNullValue())) |
| return C; |
| |
| if (isa<UndefValue>(C)) { |
| PointerType *Ptr = cast<PointerType>(C->getType()); |
| Type *Ty = GetElementPtrInst::getIndexedType(Ptr, Idxs.begin(), Idxs.end()); |
| assert(Ty != 0 && "Invalid indices for GEP!"); |
| return UndefValue::get(PointerType::get(Ty, Ptr->getAddressSpace())); |
| } |
| |
| if (C->isNullValue()) { |
| bool isNull = true; |
| for (unsigned i = 0, e = Idxs.size(); i != e; ++i) |
| if (!cast<Constant>(Idxs[i])->isNullValue()) { |
| isNull = false; |
| break; |
| } |
| if (isNull) { |
| PointerType *Ptr = cast<PointerType>(C->getType()); |
| Type *Ty = GetElementPtrInst::getIndexedType(Ptr, Idxs.begin(), |
| Idxs.end()); |
| assert(Ty != 0 && "Invalid indices for GEP!"); |
| return ConstantPointerNull::get(PointerType::get(Ty, |
| Ptr->getAddressSpace())); |
| } |
| } |
| |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) { |
| // Combine Indices - If the source pointer to this getelementptr instruction |
| // is a getelementptr instruction, combine the indices of the two |
| // getelementptr instructions into a single instruction. |
| // |
| if (CE->getOpcode() == Instruction::GetElementPtr) { |
| Type *LastTy = 0; |
| for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE); |
| I != E; ++I) |
| LastTy = *I; |
| |
| if ((LastTy && LastTy->isArrayTy()) || Idx0->isNullValue()) { |
| SmallVector<Value*, 16> NewIndices; |
| NewIndices.reserve(Idxs.size() + CE->getNumOperands()); |
| for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i) |
| NewIndices.push_back(CE->getOperand(i)); |
| |
| // Add the last index of the source with the first index of the new GEP. |
| // Make sure to handle the case when they are actually different types. |
| Constant *Combined = CE->getOperand(CE->getNumOperands()-1); |
| // Otherwise it must be an array. |
| if (!Idx0->isNullValue()) { |
| Type *IdxTy = Combined->getType(); |
| if (IdxTy != Idx0->getType()) { |
| Type *Int64Ty = Type::getInt64Ty(IdxTy->getContext()); |
| Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Int64Ty); |
| Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined, Int64Ty); |
| Combined = ConstantExpr::get(Instruction::Add, C1, C2); |
| } else { |
| Combined = |
| ConstantExpr::get(Instruction::Add, Idx0, Combined); |
| } |
| } |
| |
| NewIndices.push_back(Combined); |
| NewIndices.append(Idxs.begin() + 1, Idxs.end()); |
| return (inBounds && cast<GEPOperator>(CE)->isInBounds()) ? |
| ConstantExpr::getInBoundsGetElementPtr(CE->getOperand(0), |
| &NewIndices[0], |
| NewIndices.size()) : |
| ConstantExpr::getGetElementPtr(CE->getOperand(0), |
| &NewIndices[0], |
| NewIndices.size()); |
| } |
| } |
| |
| // Implement folding of: |
| // i32* getelementptr ([2 x i32]* bitcast ([3 x i32]* %X to [2 x i32]*), |
| // i64 0, i64 0) |
| // To: i32* getelementptr ([3 x i32]* %X, i64 0, i64 0) |
| // |
| if (CE->isCast() && Idxs.size() > 1 && Idx0->isNullValue()) { |
| if (PointerType *SPT = |
| dyn_cast<PointerType>(CE->getOperand(0)->getType())) |
| if (ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType())) |
| if (ArrayType *CAT = |
| dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType())) |
| if (CAT->getElementType() == SAT->getElementType()) |
| return inBounds ? |
| ConstantExpr::getInBoundsGetElementPtr( |
| (Constant*)CE->getOperand(0), Idxs.data(), Idxs.size()) : |
| ConstantExpr::getGetElementPtr( |
| (Constant*)CE->getOperand(0), Idxs.data(), Idxs.size()); |
| } |
| } |
| |
| // Check to see if any array indices are not within the corresponding |
| // notional array bounds. If so, try to determine if they can be factored |
| // out into preceding dimensions. |
| bool Unknown = false; |
| SmallVector<Constant *, 8> NewIdxs; |
| Type *Ty = C->getType(); |
| Type *Prev = 0; |
| for (unsigned i = 0, e = Idxs.size(); i != e; |
| Prev = Ty, Ty = cast<CompositeType>(Ty)->getTypeAtIndex(Idxs[i]), ++i) { |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(Idxs[i])) { |
| if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) |
| if (ATy->getNumElements() <= INT64_MAX && |
| ATy->getNumElements() != 0 && |
| CI->getSExtValue() >= (int64_t)ATy->getNumElements()) { |
| if (isa<SequentialType>(Prev)) { |
| // It's out of range, but we can factor it into the prior |
| // dimension. |
| NewIdxs.resize(Idxs.size()); |
| ConstantInt *Factor = ConstantInt::get(CI->getType(), |
| ATy->getNumElements()); |
| NewIdxs[i] = ConstantExpr::getSRem(CI, Factor); |
| |
| Constant *PrevIdx = cast<Constant>(Idxs[i-1]); |
| Constant *Div = ConstantExpr::getSDiv(CI, Factor); |
| |
| // Before adding, extend both operands to i64 to avoid |
| // overflow trouble. |
| if (!PrevIdx->getType()->isIntegerTy(64)) |
| PrevIdx = ConstantExpr::getSExt(PrevIdx, |
| Type::getInt64Ty(Div->getContext())); |
| if (!Div->getType()->isIntegerTy(64)) |
| Div = ConstantExpr::getSExt(Div, |
| Type::getInt64Ty(Div->getContext())); |
| |
| NewIdxs[i-1] = ConstantExpr::getAdd(PrevIdx, Div); |
| } else { |
| // It's out of range, but the prior dimension is a struct |
| // so we can't do anything about it. |
| Unknown = true; |
| } |
| } |
| } else { |
| // We don't know if it's in range or not. |
| Unknown = true; |
| } |
| } |
| |
| // If we did any factoring, start over with the adjusted indices. |
| if (!NewIdxs.empty()) { |
| for (unsigned i = 0, e = Idxs.size(); i != e; ++i) |
| if (!NewIdxs[i]) NewIdxs[i] = cast<Constant>(Idxs[i]); |
| return inBounds ? |
| ConstantExpr::getInBoundsGetElementPtr(C, NewIdxs.data(), |
| NewIdxs.size()) : |
| ConstantExpr::getGetElementPtr(C, NewIdxs.data(), NewIdxs.size()); |
| } |
| |
| // If all indices are known integers and normalized, we can do a simple |
| // check for the "inbounds" property. |
| if (!Unknown && !inBounds && |
| isa<GlobalVariable>(C) && isInBoundsIndices(Idxs.data(), Idxs.size())) |
| return ConstantExpr::getInBoundsGetElementPtr(C, Idxs.data(), Idxs.size()); |
| |
| return 0; |
| } |
| |
| Constant *llvm::ConstantFoldGetElementPtr(Constant *C, |
| bool inBounds, |
| ArrayRef<Constant *> Idxs) { |
| return ConstantFoldGetElementPtrImpl(C, inBounds, Idxs); |
| } |
| |
| Constant *llvm::ConstantFoldGetElementPtr(Constant *C, |
| bool inBounds, |
| ArrayRef<Value *> Idxs) { |
| return ConstantFoldGetElementPtrImpl(C, inBounds, Idxs); |
| } |