| //===-- ConstantFolding.cpp - Fold instructions into constants ------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines routines for folding instructions into constants. |
| // |
| // Also, to supplement the basic VMCore ConstantExpr simplifications, |
| // this file defines some additional folding routines that can make use of |
| // TargetData information. These functions cannot go in VMCore due to library |
| // dependency issues. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Analysis/ConstantFolding.h" |
| #include "llvm/Constants.h" |
| #include "llvm/DerivedTypes.h" |
| #include "llvm/Function.h" |
| #include "llvm/GlobalVariable.h" |
| #include "llvm/Instructions.h" |
| #include "llvm/Intrinsics.h" |
| #include "llvm/Operator.h" |
| #include "llvm/Analysis/ValueTracking.h" |
| #include "llvm/Target/TargetData.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/ADT/StringMap.h" |
| #include "llvm/Support/ErrorHandling.h" |
| #include "llvm/Support/GetElementPtrTypeIterator.h" |
| #include "llvm/Support/MathExtras.h" |
| #include "llvm/Support/FEnv.h" |
| #include <cerrno> |
| #include <cmath> |
| using namespace llvm; |
| |
| //===----------------------------------------------------------------------===// |
| // Constant Folding internal helper functions |
| //===----------------------------------------------------------------------===// |
| |
| /// FoldBitCast - Constant fold bitcast, symbolically evaluating it with |
| /// TargetData. This always returns a non-null constant, but it may be a |
| /// ConstantExpr if unfoldable. |
| static Constant *FoldBitCast(Constant *C, Type *DestTy, |
| const TargetData &TD) { |
| |
| // This only handles casts to vectors currently. |
| VectorType *DestVTy = dyn_cast<VectorType>(DestTy); |
| if (DestVTy == 0) |
| return ConstantExpr::getBitCast(C, DestTy); |
| |
| // If this is a scalar -> vector cast, convert the input into a <1 x scalar> |
| // vector so the code below can handle it uniformly. |
| if (isa<ConstantFP>(C) || isa<ConstantInt>(C)) { |
| Constant *Ops = C; // don't take the address of C! |
| return FoldBitCast(ConstantVector::get(Ops), DestTy, TD); |
| } |
| |
| // If this is a bitcast from constant vector -> vector, fold it. |
| ConstantVector *CV = dyn_cast<ConstantVector>(C); |
| if (CV == 0) |
| return ConstantExpr::getBitCast(C, DestTy); |
| |
| // If the element types match, VMCore can fold it. |
| unsigned NumDstElt = DestVTy->getNumElements(); |
| unsigned NumSrcElt = CV->getNumOperands(); |
| if (NumDstElt == NumSrcElt) |
| return ConstantExpr::getBitCast(C, DestTy); |
| |
| Type *SrcEltTy = CV->getType()->getElementType(); |
| Type *DstEltTy = DestVTy->getElementType(); |
| |
| // Otherwise, we're changing the number of elements in a vector, which |
| // requires endianness information to do the right thing. For example, |
| // bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>) |
| // folds to (little endian): |
| // <4 x i32> <i32 0, i32 0, i32 1, i32 0> |
| // and to (big endian): |
| // <4 x i32> <i32 0, i32 0, i32 0, i32 1> |
| |
| // First thing is first. We only want to think about integer here, so if |
| // we have something in FP form, recast it as integer. |
| if (DstEltTy->isFloatingPointTy()) { |
| // Fold to an vector of integers with same size as our FP type. |
| unsigned FPWidth = DstEltTy->getPrimitiveSizeInBits(); |
| Type *DestIVTy = |
| VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumDstElt); |
| // Recursively handle this integer conversion, if possible. |
| C = FoldBitCast(C, DestIVTy, TD); |
| if (!C) return ConstantExpr::getBitCast(C, DestTy); |
| |
| // Finally, VMCore can handle this now that #elts line up. |
| return ConstantExpr::getBitCast(C, DestTy); |
| } |
| |
| // Okay, we know the destination is integer, if the input is FP, convert |
| // it to integer first. |
| if (SrcEltTy->isFloatingPointTy()) { |
| unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits(); |
| Type *SrcIVTy = |
| VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumSrcElt); |
| // Ask VMCore to do the conversion now that #elts line up. |
| C = ConstantExpr::getBitCast(C, SrcIVTy); |
| CV = dyn_cast<ConstantVector>(C); |
| if (!CV) // If VMCore wasn't able to fold it, bail out. |
| return C; |
| } |
| |
| // Now we know that the input and output vectors are both integer vectors |
| // of the same size, and that their #elements is not the same. Do the |
| // conversion here, which depends on whether the input or output has |
| // more elements. |
| bool isLittleEndian = TD.isLittleEndian(); |
| |
| SmallVector<Constant*, 32> Result; |
| if (NumDstElt < NumSrcElt) { |
| // Handle: bitcast (<4 x i32> <i32 0, i32 1, i32 2, i32 3> to <2 x i64>) |
| Constant *Zero = Constant::getNullValue(DstEltTy); |
| unsigned Ratio = NumSrcElt/NumDstElt; |
| unsigned SrcBitSize = SrcEltTy->getPrimitiveSizeInBits(); |
| unsigned SrcElt = 0; |
| for (unsigned i = 0; i != NumDstElt; ++i) { |
| // Build each element of the result. |
| Constant *Elt = Zero; |
| unsigned ShiftAmt = isLittleEndian ? 0 : SrcBitSize*(Ratio-1); |
| for (unsigned j = 0; j != Ratio; ++j) { |
| Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(SrcElt++)); |
| if (!Src) // Reject constantexpr elements. |
| return ConstantExpr::getBitCast(C, DestTy); |
| |
| // Zero extend the element to the right size. |
| Src = ConstantExpr::getZExt(Src, Elt->getType()); |
| |
| // Shift it to the right place, depending on endianness. |
| Src = ConstantExpr::getShl(Src, |
| ConstantInt::get(Src->getType(), ShiftAmt)); |
| ShiftAmt += isLittleEndian ? SrcBitSize : -SrcBitSize; |
| |
| // Mix it in. |
| Elt = ConstantExpr::getOr(Elt, Src); |
| } |
| Result.push_back(Elt); |
| } |
| } else { |
| // Handle: bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>) |
| unsigned Ratio = NumDstElt/NumSrcElt; |
| unsigned DstBitSize = DstEltTy->getPrimitiveSizeInBits(); |
| |
| // Loop over each source value, expanding into multiple results. |
| for (unsigned i = 0; i != NumSrcElt; ++i) { |
| Constant *Src = dyn_cast<ConstantInt>(CV->getOperand(i)); |
| if (!Src) // Reject constantexpr elements. |
| return ConstantExpr::getBitCast(C, DestTy); |
| |
| unsigned ShiftAmt = isLittleEndian ? 0 : DstBitSize*(Ratio-1); |
| for (unsigned j = 0; j != Ratio; ++j) { |
| // Shift the piece of the value into the right place, depending on |
| // endianness. |
| Constant *Elt = ConstantExpr::getLShr(Src, |
| ConstantInt::get(Src->getType(), ShiftAmt)); |
| ShiftAmt += isLittleEndian ? DstBitSize : -DstBitSize; |
| |
| // Truncate and remember this piece. |
| Result.push_back(ConstantExpr::getTrunc(Elt, DstEltTy)); |
| } |
| } |
| } |
| |
| return ConstantVector::get(Result); |
| } |
| |
| |
| /// IsConstantOffsetFromGlobal - If this constant is actually a constant offset |
| /// from a global, return the global and the constant. Because of |
| /// constantexprs, this function is recursive. |
| static bool IsConstantOffsetFromGlobal(Constant *C, GlobalValue *&GV, |
| int64_t &Offset, const TargetData &TD) { |
| // Trivial case, constant is the global. |
| if ((GV = dyn_cast<GlobalValue>(C))) { |
| Offset = 0; |
| return true; |
| } |
| |
| // Otherwise, if this isn't a constant expr, bail out. |
| ConstantExpr *CE = dyn_cast<ConstantExpr>(C); |
| if (!CE) return false; |
| |
| // Look through ptr->int and ptr->ptr casts. |
| if (CE->getOpcode() == Instruction::PtrToInt || |
| CE->getOpcode() == Instruction::BitCast) |
| return IsConstantOffsetFromGlobal(CE->getOperand(0), GV, Offset, TD); |
| |
| // i32* getelementptr ([5 x i32]* @a, i32 0, i32 5) |
| if (CE->getOpcode() == Instruction::GetElementPtr) { |
| // Cannot compute this if the element type of the pointer is missing size |
| // info. |
| if (!cast<PointerType>(CE->getOperand(0)->getType()) |
| ->getElementType()->isSized()) |
| return false; |
| |
| // If the base isn't a global+constant, we aren't either. |
| if (!IsConstantOffsetFromGlobal(CE->getOperand(0), GV, Offset, TD)) |
| return false; |
| |
| // Otherwise, add any offset that our operands provide. |
| gep_type_iterator GTI = gep_type_begin(CE); |
| for (User::const_op_iterator i = CE->op_begin() + 1, e = CE->op_end(); |
| i != e; ++i, ++GTI) { |
| ConstantInt *CI = dyn_cast<ConstantInt>(*i); |
| if (!CI) return false; // Index isn't a simple constant? |
| if (CI->isZero()) continue; // Not adding anything. |
| |
| if (StructType *ST = dyn_cast<StructType>(*GTI)) { |
| // N = N + Offset |
| Offset += TD.getStructLayout(ST)->getElementOffset(CI->getZExtValue()); |
| } else { |
| SequentialType *SQT = cast<SequentialType>(*GTI); |
| Offset += TD.getTypeAllocSize(SQT->getElementType())*CI->getSExtValue(); |
| } |
| } |
| return true; |
| } |
| |
| return false; |
| } |
| |
| /// ReadDataFromGlobal - Recursive helper to read bits out of global. C is the |
| /// constant being copied out of. ByteOffset is an offset into C. CurPtr is the |
| /// pointer to copy results into and BytesLeft is the number of bytes left in |
| /// the CurPtr buffer. TD is the target data. |
| static bool ReadDataFromGlobal(Constant *C, uint64_t ByteOffset, |
| unsigned char *CurPtr, unsigned BytesLeft, |
| const TargetData &TD) { |
| assert(ByteOffset <= TD.getTypeAllocSize(C->getType()) && |
| "Out of range access"); |
| |
| // If this element is zero or undefined, we can just return since *CurPtr is |
| // zero initialized. |
| if (isa<ConstantAggregateZero>(C) || isa<UndefValue>(C)) |
| return true; |
| |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) { |
| if (CI->getBitWidth() > 64 || |
| (CI->getBitWidth() & 7) != 0) |
| return false; |
| |
| uint64_t Val = CI->getZExtValue(); |
| unsigned IntBytes = unsigned(CI->getBitWidth()/8); |
| |
| for (unsigned i = 0; i != BytesLeft && ByteOffset != IntBytes; ++i) { |
| CurPtr[i] = (unsigned char)(Val >> (ByteOffset * 8)); |
| ++ByteOffset; |
| } |
| return true; |
| } |
| |
| if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) { |
| if (CFP->getType()->isDoubleTy()) { |
| C = FoldBitCast(C, Type::getInt64Ty(C->getContext()), TD); |
| return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD); |
| } |
| if (CFP->getType()->isFloatTy()){ |
| C = FoldBitCast(C, Type::getInt32Ty(C->getContext()), TD); |
| return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, TD); |
| } |
| return false; |
| } |
| |
| if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) { |
| const StructLayout *SL = TD.getStructLayout(CS->getType()); |
| unsigned Index = SL->getElementContainingOffset(ByteOffset); |
| uint64_t CurEltOffset = SL->getElementOffset(Index); |
| ByteOffset -= CurEltOffset; |
| |
| while (1) { |
| // If the element access is to the element itself and not to tail padding, |
| // read the bytes from the element. |
| uint64_t EltSize = TD.getTypeAllocSize(CS->getOperand(Index)->getType()); |
| |
| if (ByteOffset < EltSize && |
| !ReadDataFromGlobal(CS->getOperand(Index), ByteOffset, CurPtr, |
| BytesLeft, TD)) |
| return false; |
| |
| ++Index; |
| |
| // Check to see if we read from the last struct element, if so we're done. |
| if (Index == CS->getType()->getNumElements()) |
| return true; |
| |
| // If we read all of the bytes we needed from this element we're done. |
| uint64_t NextEltOffset = SL->getElementOffset(Index); |
| |
| if (BytesLeft <= NextEltOffset-CurEltOffset-ByteOffset) |
| return true; |
| |
| // Move to the next element of the struct. |
| CurPtr += NextEltOffset-CurEltOffset-ByteOffset; |
| BytesLeft -= NextEltOffset-CurEltOffset-ByteOffset; |
| ByteOffset = 0; |
| CurEltOffset = NextEltOffset; |
| } |
| // not reached. |
| } |
| |
| if (ConstantArray *CA = dyn_cast<ConstantArray>(C)) { |
| uint64_t EltSize = TD.getTypeAllocSize(CA->getType()->getElementType()); |
| uint64_t Index = ByteOffset / EltSize; |
| uint64_t Offset = ByteOffset - Index * EltSize; |
| for (; Index != CA->getType()->getNumElements(); ++Index) { |
| if (!ReadDataFromGlobal(CA->getOperand(Index), Offset, CurPtr, |
| BytesLeft, TD)) |
| return false; |
| if (EltSize >= BytesLeft) |
| return true; |
| |
| Offset = 0; |
| BytesLeft -= EltSize; |
| CurPtr += EltSize; |
| } |
| return true; |
| } |
| |
| if (ConstantVector *CV = dyn_cast<ConstantVector>(C)) { |
| uint64_t EltSize = TD.getTypeAllocSize(CV->getType()->getElementType()); |
| uint64_t Index = ByteOffset / EltSize; |
| uint64_t Offset = ByteOffset - Index * EltSize; |
| for (; Index != CV->getType()->getNumElements(); ++Index) { |
| if (!ReadDataFromGlobal(CV->getOperand(Index), Offset, CurPtr, |
| BytesLeft, TD)) |
| return false; |
| if (EltSize >= BytesLeft) |
| return true; |
| |
| Offset = 0; |
| BytesLeft -= EltSize; |
| CurPtr += EltSize; |
| } |
| return true; |
| } |
| |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) { |
| if (CE->getOpcode() == Instruction::IntToPtr && |
| CE->getOperand(0)->getType() == TD.getIntPtrType(CE->getContext())) |
| return ReadDataFromGlobal(CE->getOperand(0), ByteOffset, CurPtr, |
| BytesLeft, TD); |
| } |
| |
| // Otherwise, unknown initializer type. |
| return false; |
| } |
| |
| static Constant *FoldReinterpretLoadFromConstPtr(Constant *C, |
| const TargetData &TD) { |
| Type *LoadTy = cast<PointerType>(C->getType())->getElementType(); |
| IntegerType *IntType = dyn_cast<IntegerType>(LoadTy); |
| |
| // If this isn't an integer load we can't fold it directly. |
| if (!IntType) { |
| // If this is a float/double load, we can try folding it as an int32/64 load |
| // and then bitcast the result. This can be useful for union cases. Note |
| // that address spaces don't matter here since we're not going to result in |
| // an actual new load. |
| Type *MapTy; |
| if (LoadTy->isFloatTy()) |
| MapTy = Type::getInt32PtrTy(C->getContext()); |
| else if (LoadTy->isDoubleTy()) |
| MapTy = Type::getInt64PtrTy(C->getContext()); |
| else if (LoadTy->isVectorTy()) { |
| MapTy = IntegerType::get(C->getContext(), |
| TD.getTypeAllocSizeInBits(LoadTy)); |
| MapTy = PointerType::getUnqual(MapTy); |
| } else |
| return 0; |
| |
| C = FoldBitCast(C, MapTy, TD); |
| if (Constant *Res = FoldReinterpretLoadFromConstPtr(C, TD)) |
| return FoldBitCast(Res, LoadTy, TD); |
| return 0; |
| } |
| |
| unsigned BytesLoaded = (IntType->getBitWidth() + 7) / 8; |
| if (BytesLoaded > 32 || BytesLoaded == 0) return 0; |
| |
| GlobalValue *GVal; |
| int64_t Offset; |
| if (!IsConstantOffsetFromGlobal(C, GVal, Offset, TD)) |
| return 0; |
| |
| GlobalVariable *GV = dyn_cast<GlobalVariable>(GVal); |
| if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() || |
| !GV->getInitializer()->getType()->isSized()) |
| return 0; |
| |
| // If we're loading off the beginning of the global, some bytes may be valid, |
| // but we don't try to handle this. |
| if (Offset < 0) return 0; |
| |
| // If we're not accessing anything in this constant, the result is undefined. |
| if (uint64_t(Offset) >= TD.getTypeAllocSize(GV->getInitializer()->getType())) |
| return UndefValue::get(IntType); |
| |
| unsigned char RawBytes[32] = {0}; |
| if (!ReadDataFromGlobal(GV->getInitializer(), Offset, RawBytes, |
| BytesLoaded, TD)) |
| return 0; |
| |
| APInt ResultVal = APInt(IntType->getBitWidth(), RawBytes[BytesLoaded-1]); |
| for (unsigned i = 1; i != BytesLoaded; ++i) { |
| ResultVal <<= 8; |
| ResultVal |= RawBytes[BytesLoaded-1-i]; |
| } |
| |
| return ConstantInt::get(IntType->getContext(), ResultVal); |
| } |
| |
| /// ConstantFoldLoadFromConstPtr - Return the value that a load from C would |
| /// produce if it is constant and determinable. If this is not determinable, |
| /// return null. |
| Constant *llvm::ConstantFoldLoadFromConstPtr(Constant *C, |
| const TargetData *TD) { |
| // First, try the easy cases: |
| if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) |
| if (GV->isConstant() && GV->hasDefinitiveInitializer()) |
| return GV->getInitializer(); |
| |
| // If the loaded value isn't a constant expr, we can't handle it. |
| ConstantExpr *CE = dyn_cast<ConstantExpr>(C); |
| if (!CE) return 0; |
| |
| if (CE->getOpcode() == Instruction::GetElementPtr) { |
| if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0))) |
| if (GV->isConstant() && GV->hasDefinitiveInitializer()) |
| if (Constant *V = |
| ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE)) |
| return V; |
| } |
| |
| // Instead of loading constant c string, use corresponding integer value |
| // directly if string length is small enough. |
| std::string Str; |
| if (TD && GetConstantStringInfo(CE, Str) && !Str.empty()) { |
| unsigned StrLen = Str.length(); |
| Type *Ty = cast<PointerType>(CE->getType())->getElementType(); |
| unsigned NumBits = Ty->getPrimitiveSizeInBits(); |
| // Replace load with immediate integer if the result is an integer or fp |
| // value. |
| if ((NumBits >> 3) == StrLen + 1 && (NumBits & 7) == 0 && |
| (isa<IntegerType>(Ty) || Ty->isFloatingPointTy())) { |
| APInt StrVal(NumBits, 0); |
| APInt SingleChar(NumBits, 0); |
| if (TD->isLittleEndian()) { |
| for (signed i = StrLen-1; i >= 0; i--) { |
| SingleChar = (uint64_t) Str[i] & UCHAR_MAX; |
| StrVal = (StrVal << 8) | SingleChar; |
| } |
| } else { |
| for (unsigned i = 0; i < StrLen; i++) { |
| SingleChar = (uint64_t) Str[i] & UCHAR_MAX; |
| StrVal = (StrVal << 8) | SingleChar; |
| } |
| // Append NULL at the end. |
| SingleChar = 0; |
| StrVal = (StrVal << 8) | SingleChar; |
| } |
| |
| Constant *Res = ConstantInt::get(CE->getContext(), StrVal); |
| if (Ty->isFloatingPointTy()) |
| Res = ConstantExpr::getBitCast(Res, Ty); |
| return Res; |
| } |
| } |
| |
| // If this load comes from anywhere in a constant global, and if the global |
| // is all undef or zero, we know what it loads. |
| if (GlobalVariable *GV = |
| dyn_cast<GlobalVariable>(GetUnderlyingObject(CE, TD))) { |
| if (GV->isConstant() && GV->hasDefinitiveInitializer()) { |
| Type *ResTy = cast<PointerType>(C->getType())->getElementType(); |
| if (GV->getInitializer()->isNullValue()) |
| return Constant::getNullValue(ResTy); |
| if (isa<UndefValue>(GV->getInitializer())) |
| return UndefValue::get(ResTy); |
| } |
| } |
| |
| // Try hard to fold loads from bitcasted strange and non-type-safe things. We |
| // currently don't do any of this for big endian systems. It can be |
| // generalized in the future if someone is interested. |
| if (TD && TD->isLittleEndian()) |
| return FoldReinterpretLoadFromConstPtr(CE, *TD); |
| return 0; |
| } |
| |
| static Constant *ConstantFoldLoadInst(const LoadInst *LI, const TargetData *TD){ |
| if (LI->isVolatile()) return 0; |
| |
| if (Constant *C = dyn_cast<Constant>(LI->getOperand(0))) |
| return ConstantFoldLoadFromConstPtr(C, TD); |
| |
| return 0; |
| } |
| |
| /// SymbolicallyEvaluateBinop - One of Op0/Op1 is a constant expression. |
| /// Attempt to symbolically evaluate the result of a binary operator merging |
| /// these together. If target data info is available, it is provided as TD, |
| /// otherwise TD is null. |
| static Constant *SymbolicallyEvaluateBinop(unsigned Opc, Constant *Op0, |
| Constant *Op1, const TargetData *TD){ |
| // SROA |
| |
| // Fold (and 0xffffffff00000000, (shl x, 32)) -> shl. |
| // Fold (lshr (or X, Y), 32) -> (lshr [X/Y], 32) if one doesn't contribute |
| // bits. |
| |
| |
| // If the constant expr is something like &A[123] - &A[4].f, fold this into a |
| // constant. This happens frequently when iterating over a global array. |
| if (Opc == Instruction::Sub && TD) { |
| GlobalValue *GV1, *GV2; |
| int64_t Offs1, Offs2; |
| |
| if (IsConstantOffsetFromGlobal(Op0, GV1, Offs1, *TD)) |
| if (IsConstantOffsetFromGlobal(Op1, GV2, Offs2, *TD) && |
| GV1 == GV2) { |
| // (&GV+C1) - (&GV+C2) -> C1-C2, pointer arithmetic cannot overflow. |
| return ConstantInt::get(Op0->getType(), Offs1-Offs2); |
| } |
| } |
| |
| return 0; |
| } |
| |
| /// CastGEPIndices - If array indices are not pointer-sized integers, |
| /// explicitly cast them so that they aren't implicitly casted by the |
| /// getelementptr. |
| static Constant *CastGEPIndices(ArrayRef<Constant *> Ops, |
| Type *ResultTy, |
| const TargetData *TD) { |
| if (!TD) return 0; |
| Type *IntPtrTy = TD->getIntPtrType(ResultTy->getContext()); |
| |
| bool Any = false; |
| SmallVector<Constant*, 32> NewIdxs; |
| for (unsigned i = 1, e = Ops.size(); i != e; ++i) { |
| if ((i == 1 || |
| !isa<StructType>(GetElementPtrInst::getIndexedType(Ops[0]->getType(), |
| Ops.slice(1, i-1)))) && |
| Ops[i]->getType() != IntPtrTy) { |
| Any = true; |
| NewIdxs.push_back(ConstantExpr::getCast(CastInst::getCastOpcode(Ops[i], |
| true, |
| IntPtrTy, |
| true), |
| Ops[i], IntPtrTy)); |
| } else |
| NewIdxs.push_back(Ops[i]); |
| } |
| if (!Any) return 0; |
| |
| Constant *C = |
| ConstantExpr::getGetElementPtr(Ops[0], NewIdxs); |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) |
| if (Constant *Folded = ConstantFoldConstantExpression(CE, TD)) |
| C = Folded; |
| return C; |
| } |
| |
| /// SymbolicallyEvaluateGEP - If we can symbolically evaluate the specified GEP |
| /// constant expression, do so. |
| static Constant *SymbolicallyEvaluateGEP(ArrayRef<Constant *> Ops, |
| Type *ResultTy, |
| const TargetData *TD) { |
| Constant *Ptr = Ops[0]; |
| if (!TD || !cast<PointerType>(Ptr->getType())->getElementType()->isSized()) |
| return 0; |
| |
| Type *IntPtrTy = TD->getIntPtrType(Ptr->getContext()); |
| |
| // If this is a constant expr gep that is effectively computing an |
| // "offsetof", fold it into 'cast int Size to T*' instead of 'gep 0, 0, 12' |
| for (unsigned i = 1, e = Ops.size(); i != e; ++i) |
| if (!isa<ConstantInt>(Ops[i])) { |
| |
| // If this is "gep i8* Ptr, (sub 0, V)", fold this as: |
| // "inttoptr (sub (ptrtoint Ptr), V)" |
| if (Ops.size() == 2 && |
| cast<PointerType>(ResultTy)->getElementType()->isIntegerTy(8)) { |
| ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[1]); |
| assert((CE == 0 || CE->getType() == IntPtrTy) && |
| "CastGEPIndices didn't canonicalize index types!"); |
| if (CE && CE->getOpcode() == Instruction::Sub && |
| CE->getOperand(0)->isNullValue()) { |
| Constant *Res = ConstantExpr::getPtrToInt(Ptr, CE->getType()); |
| Res = ConstantExpr::getSub(Res, CE->getOperand(1)); |
| Res = ConstantExpr::getIntToPtr(Res, ResultTy); |
| if (ConstantExpr *ResCE = dyn_cast<ConstantExpr>(Res)) |
| Res = ConstantFoldConstantExpression(ResCE, TD); |
| return Res; |
| } |
| } |
| return 0; |
| } |
| |
| unsigned BitWidth = TD->getTypeSizeInBits(IntPtrTy); |
| APInt Offset = |
| APInt(BitWidth, TD->getIndexedOffset(Ptr->getType(), |
| makeArrayRef((Value **)Ops.data() + 1, |
| Ops.size() - 1))); |
| Ptr = cast<Constant>(Ptr->stripPointerCasts()); |
| |
| // If this is a GEP of a GEP, fold it all into a single GEP. |
| while (GEPOperator *GEP = dyn_cast<GEPOperator>(Ptr)) { |
| SmallVector<Value *, 4> NestedOps(GEP->op_begin()+1, GEP->op_end()); |
| |
| // Do not try the incorporate the sub-GEP if some index is not a number. |
| bool AllConstantInt = true; |
| for (unsigned i = 0, e = NestedOps.size(); i != e; ++i) |
| if (!isa<ConstantInt>(NestedOps[i])) { |
| AllConstantInt = false; |
| break; |
| } |
| if (!AllConstantInt) |
| break; |
| |
| Ptr = cast<Constant>(GEP->getOperand(0)); |
| Offset += APInt(BitWidth, |
| TD->getIndexedOffset(Ptr->getType(), NestedOps)); |
| Ptr = cast<Constant>(Ptr->stripPointerCasts()); |
| } |
| |
| // If the base value for this address is a literal integer value, fold the |
| // getelementptr to the resulting integer value casted to the pointer type. |
| APInt BasePtr(BitWidth, 0); |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr)) |
| if (CE->getOpcode() == Instruction::IntToPtr) |
| if (ConstantInt *Base = dyn_cast<ConstantInt>(CE->getOperand(0))) |
| BasePtr = Base->getValue().zextOrTrunc(BitWidth); |
| if (Ptr->isNullValue() || BasePtr != 0) { |
| Constant *C = ConstantInt::get(Ptr->getContext(), Offset+BasePtr); |
| return ConstantExpr::getIntToPtr(C, ResultTy); |
| } |
| |
| // Otherwise form a regular getelementptr. Recompute the indices so that |
| // we eliminate over-indexing of the notional static type array bounds. |
| // This makes it easy to determine if the getelementptr is "inbounds". |
| // Also, this helps GlobalOpt do SROA on GlobalVariables. |
| Type *Ty = Ptr->getType(); |
| SmallVector<Constant*, 32> NewIdxs; |
| do { |
| if (SequentialType *ATy = dyn_cast<SequentialType>(Ty)) { |
| if (ATy->isPointerTy()) { |
| // The only pointer indexing we'll do is on the first index of the GEP. |
| if (!NewIdxs.empty()) |
| break; |
| |
| // Only handle pointers to sized types, not pointers to functions. |
| if (!ATy->getElementType()->isSized()) |
| return 0; |
| } |
| |
| // Determine which element of the array the offset points into. |
| APInt ElemSize(BitWidth, TD->getTypeAllocSize(ATy->getElementType())); |
| IntegerType *IntPtrTy = TD->getIntPtrType(Ty->getContext()); |
| if (ElemSize == 0) |
| // The element size is 0. This may be [0 x Ty]*, so just use a zero |
| // index for this level and proceed to the next level to see if it can |
| // accommodate the offset. |
| NewIdxs.push_back(ConstantInt::get(IntPtrTy, 0)); |
| else { |
| // The element size is non-zero divide the offset by the element |
| // size (rounding down), to compute the index at this level. |
| APInt NewIdx = Offset.udiv(ElemSize); |
| Offset -= NewIdx * ElemSize; |
| NewIdxs.push_back(ConstantInt::get(IntPtrTy, NewIdx)); |
| } |
| Ty = ATy->getElementType(); |
| } else if (StructType *STy = dyn_cast<StructType>(Ty)) { |
| // Determine which field of the struct the offset points into. The |
| // getZExtValue is at least as safe as the StructLayout API because we |
| // know the offset is within the struct at this point. |
| const StructLayout &SL = *TD->getStructLayout(STy); |
| unsigned ElIdx = SL.getElementContainingOffset(Offset.getZExtValue()); |
| NewIdxs.push_back(ConstantInt::get(Type::getInt32Ty(Ty->getContext()), |
| ElIdx)); |
| Offset -= APInt(BitWidth, SL.getElementOffset(ElIdx)); |
| Ty = STy->getTypeAtIndex(ElIdx); |
| } else { |
| // We've reached some non-indexable type. |
| break; |
| } |
| } while (Ty != cast<PointerType>(ResultTy)->getElementType()); |
| |
| // If we haven't used up the entire offset by descending the static |
| // type, then the offset is pointing into the middle of an indivisible |
| // member, so we can't simplify it. |
| if (Offset != 0) |
| return 0; |
| |
| // Create a GEP. |
| Constant *C = |
| ConstantExpr::getGetElementPtr(Ptr, NewIdxs); |
| assert(cast<PointerType>(C->getType())->getElementType() == Ty && |
| "Computed GetElementPtr has unexpected type!"); |
| |
| // If we ended up indexing a member with a type that doesn't match |
| // the type of what the original indices indexed, add a cast. |
| if (Ty != cast<PointerType>(ResultTy)->getElementType()) |
| C = FoldBitCast(C, ResultTy, *TD); |
| |
| return C; |
| } |
| |
| |
| |
| //===----------------------------------------------------------------------===// |
| // Constant Folding public APIs |
| //===----------------------------------------------------------------------===// |
| |
| /// ConstantFoldInstruction - Try to constant fold the specified instruction. |
| /// If successful, the constant result is returned, if not, null is returned. |
| /// Note that this fails if not all of the operands are constant. Otherwise, |
| /// this function can only fail when attempting to fold instructions like loads |
| /// and stores, which have no constant expression form. |
| Constant *llvm::ConstantFoldInstruction(Instruction *I, const TargetData *TD) { |
| // Handle PHI nodes quickly here... |
| if (PHINode *PN = dyn_cast<PHINode>(I)) { |
| Constant *CommonValue = 0; |
| |
| for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { |
| Value *Incoming = PN->getIncomingValue(i); |
| // If the incoming value is undef then skip it. Note that while we could |
| // skip the value if it is equal to the phi node itself we choose not to |
| // because that would break the rule that constant folding only applies if |
| // all operands are constants. |
| if (isa<UndefValue>(Incoming)) |
| continue; |
| // If the incoming value is not a constant, or is a different constant to |
| // the one we saw previously, then give up. |
| Constant *C = dyn_cast<Constant>(Incoming); |
| if (!C || (CommonValue && C != CommonValue)) |
| return 0; |
| CommonValue = C; |
| } |
| |
| // If we reach here, all incoming values are the same constant or undef. |
| return CommonValue ? CommonValue : UndefValue::get(PN->getType()); |
| } |
| |
| // Scan the operand list, checking to see if they are all constants, if so, |
| // hand off to ConstantFoldInstOperands. |
| SmallVector<Constant*, 8> Ops; |
| for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i) |
| if (Constant *Op = dyn_cast<Constant>(*i)) |
| Ops.push_back(Op); |
| else |
| return 0; // All operands not constant! |
| |
| if (const CmpInst *CI = dyn_cast<CmpInst>(I)) |
| return ConstantFoldCompareInstOperands(CI->getPredicate(), Ops[0], Ops[1], |
| TD); |
| |
| if (const LoadInst *LI = dyn_cast<LoadInst>(I)) |
| return ConstantFoldLoadInst(LI, TD); |
| |
| if (InsertValueInst *IVI = dyn_cast<InsertValueInst>(I)) |
| return ConstantExpr::getInsertValue( |
| cast<Constant>(IVI->getAggregateOperand()), |
| cast<Constant>(IVI->getInsertedValueOperand()), |
| IVI->getIndices()); |
| |
| if (ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(I)) |
| return ConstantExpr::getExtractValue( |
| cast<Constant>(EVI->getAggregateOperand()), |
| EVI->getIndices()); |
| |
| return ConstantFoldInstOperands(I->getOpcode(), I->getType(), Ops, TD); |
| } |
| |
| /// ConstantFoldConstantExpression - Attempt to fold the constant expression |
| /// using the specified TargetData. If successful, the constant result is |
| /// result is returned, if not, null is returned. |
| Constant *llvm::ConstantFoldConstantExpression(const ConstantExpr *CE, |
| const TargetData *TD) { |
| SmallVector<Constant*, 8> Ops; |
| for (User::const_op_iterator i = CE->op_begin(), e = CE->op_end(); |
| i != e; ++i) { |
| Constant *NewC = cast<Constant>(*i); |
| // Recursively fold the ConstantExpr's operands. |
| if (ConstantExpr *NewCE = dyn_cast<ConstantExpr>(NewC)) |
| NewC = ConstantFoldConstantExpression(NewCE, TD); |
| Ops.push_back(NewC); |
| } |
| |
| if (CE->isCompare()) |
| return ConstantFoldCompareInstOperands(CE->getPredicate(), Ops[0], Ops[1], |
| TD); |
| return ConstantFoldInstOperands(CE->getOpcode(), CE->getType(), Ops, TD); |
| } |
| |
| /// ConstantFoldInstOperands - Attempt to constant fold an instruction with the |
| /// specified opcode and operands. If successful, the constant result is |
| /// returned, if not, null is returned. Note that this function can fail when |
| /// attempting to fold instructions like loads and stores, which have no |
| /// constant expression form. |
| /// |
| /// TODO: This function neither utilizes nor preserves nsw/nuw/inbounds/etc |
| /// information, due to only being passed an opcode and operands. Constant |
| /// folding using this function strips this information. |
| /// |
| Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, Type *DestTy, |
| ArrayRef<Constant *> Ops, |
| const TargetData *TD) { |
| // Handle easy binops first. |
| if (Instruction::isBinaryOp(Opcode)) { |
| if (isa<ConstantExpr>(Ops[0]) || isa<ConstantExpr>(Ops[1])) |
| if (Constant *C = SymbolicallyEvaluateBinop(Opcode, Ops[0], Ops[1], TD)) |
| return C; |
| |
| return ConstantExpr::get(Opcode, Ops[0], Ops[1]); |
| } |
| |
| switch (Opcode) { |
| default: return 0; |
| case Instruction::ICmp: |
| case Instruction::FCmp: assert(0 && "Invalid for compares"); |
| case Instruction::Call: |
| if (Function *F = dyn_cast<Function>(Ops.back())) |
| if (canConstantFoldCallTo(F)) |
| return ConstantFoldCall(F, Ops.slice(0, Ops.size() - 1)); |
| return 0; |
| case Instruction::PtrToInt: |
| // If the input is a inttoptr, eliminate the pair. This requires knowing |
| // the width of a pointer, so it can't be done in ConstantExpr::getCast. |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[0])) { |
| if (TD && CE->getOpcode() == Instruction::IntToPtr) { |
| Constant *Input = CE->getOperand(0); |
| unsigned InWidth = Input->getType()->getScalarSizeInBits(); |
| if (TD->getPointerSizeInBits() < InWidth) { |
| Constant *Mask = |
| ConstantInt::get(CE->getContext(), APInt::getLowBitsSet(InWidth, |
| TD->getPointerSizeInBits())); |
| Input = ConstantExpr::getAnd(Input, Mask); |
| } |
| // Do a zext or trunc to get to the dest size. |
| return ConstantExpr::getIntegerCast(Input, DestTy, false); |
| } |
| } |
| return ConstantExpr::getCast(Opcode, Ops[0], DestTy); |
| case Instruction::IntToPtr: |
| // If the input is a ptrtoint, turn the pair into a ptr to ptr bitcast if |
| // the int size is >= the ptr size. This requires knowing the width of a |
| // pointer, so it can't be done in ConstantExpr::getCast. |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[0])) |
| if (TD && |
| TD->getPointerSizeInBits() <= CE->getType()->getScalarSizeInBits() && |
| CE->getOpcode() == Instruction::PtrToInt) |
| return FoldBitCast(CE->getOperand(0), DestTy, *TD); |
| |
| return ConstantExpr::getCast(Opcode, Ops[0], DestTy); |
| case Instruction::Trunc: |
| case Instruction::ZExt: |
| case Instruction::SExt: |
| case Instruction::FPTrunc: |
| case Instruction::FPExt: |
| case Instruction::UIToFP: |
| case Instruction::SIToFP: |
| case Instruction::FPToUI: |
| case Instruction::FPToSI: |
| return ConstantExpr::getCast(Opcode, Ops[0], DestTy); |
| case Instruction::BitCast: |
| if (TD) |
| return FoldBitCast(Ops[0], DestTy, *TD); |
| return ConstantExpr::getBitCast(Ops[0], DestTy); |
| case Instruction::Select: |
| return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]); |
| case Instruction::ExtractElement: |
| return ConstantExpr::getExtractElement(Ops[0], Ops[1]); |
| case Instruction::InsertElement: |
| return ConstantExpr::getInsertElement(Ops[0], Ops[1], Ops[2]); |
| case Instruction::ShuffleVector: |
| return ConstantExpr::getShuffleVector(Ops[0], Ops[1], Ops[2]); |
| case Instruction::GetElementPtr: |
| if (Constant *C = CastGEPIndices(Ops, DestTy, TD)) |
| return C; |
| if (Constant *C = SymbolicallyEvaluateGEP(Ops, DestTy, TD)) |
| return C; |
| |
| return ConstantExpr::getGetElementPtr(Ops[0], Ops.slice(1)); |
| } |
| } |
| |
| /// ConstantFoldCompareInstOperands - Attempt to constant fold a compare |
| /// instruction (icmp/fcmp) with the specified operands. If it fails, it |
| /// returns a constant expression of the specified operands. |
| /// |
| Constant *llvm::ConstantFoldCompareInstOperands(unsigned Predicate, |
| Constant *Ops0, Constant *Ops1, |
| const TargetData *TD) { |
| // fold: icmp (inttoptr x), null -> icmp x, 0 |
| // fold: icmp (ptrtoint x), 0 -> icmp x, null |
| // fold: icmp (inttoptr x), (inttoptr y) -> icmp trunc/zext x, trunc/zext y |
| // fold: icmp (ptrtoint x), (ptrtoint y) -> icmp x, y |
| // |
| // ConstantExpr::getCompare cannot do this, because it doesn't have TD |
| // around to know if bit truncation is happening. |
| if (ConstantExpr *CE0 = dyn_cast<ConstantExpr>(Ops0)) { |
| if (TD && Ops1->isNullValue()) { |
| Type *IntPtrTy = TD->getIntPtrType(CE0->getContext()); |
| if (CE0->getOpcode() == Instruction::IntToPtr) { |
| // Convert the integer value to the right size to ensure we get the |
| // proper extension or truncation. |
| Constant *C = ConstantExpr::getIntegerCast(CE0->getOperand(0), |
| IntPtrTy, false); |
| Constant *Null = Constant::getNullValue(C->getType()); |
| return ConstantFoldCompareInstOperands(Predicate, C, Null, TD); |
| } |
| |
| // Only do this transformation if the int is intptrty in size, otherwise |
| // there is a truncation or extension that we aren't modeling. |
| if (CE0->getOpcode() == Instruction::PtrToInt && |
| CE0->getType() == IntPtrTy) { |
| Constant *C = CE0->getOperand(0); |
| Constant *Null = Constant::getNullValue(C->getType()); |
| return ConstantFoldCompareInstOperands(Predicate, C, Null, TD); |
| } |
| } |
| |
| if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(Ops1)) { |
| if (TD && CE0->getOpcode() == CE1->getOpcode()) { |
| Type *IntPtrTy = TD->getIntPtrType(CE0->getContext()); |
| |
| if (CE0->getOpcode() == Instruction::IntToPtr) { |
| // Convert the integer value to the right size to ensure we get the |
| // proper extension or truncation. |
| Constant *C0 = ConstantExpr::getIntegerCast(CE0->getOperand(0), |
| IntPtrTy, false); |
| Constant *C1 = ConstantExpr::getIntegerCast(CE1->getOperand(0), |
| IntPtrTy, false); |
| return ConstantFoldCompareInstOperands(Predicate, C0, C1, TD); |
| } |
| |
| // Only do this transformation if the int is intptrty in size, otherwise |
| // there is a truncation or extension that we aren't modeling. |
| if ((CE0->getOpcode() == Instruction::PtrToInt && |
| CE0->getType() == IntPtrTy && |
| CE0->getOperand(0)->getType() == CE1->getOperand(0)->getType())) |
| return ConstantFoldCompareInstOperands(Predicate, CE0->getOperand(0), |
| CE1->getOperand(0), TD); |
| } |
| } |
| |
| // icmp eq (or x, y), 0 -> (icmp eq x, 0) & (icmp eq y, 0) |
| // icmp ne (or x, y), 0 -> (icmp ne x, 0) | (icmp ne y, 0) |
| if ((Predicate == ICmpInst::ICMP_EQ || Predicate == ICmpInst::ICMP_NE) && |
| CE0->getOpcode() == Instruction::Or && Ops1->isNullValue()) { |
| Constant *LHS = |
| ConstantFoldCompareInstOperands(Predicate, CE0->getOperand(0), Ops1,TD); |
| Constant *RHS = |
| ConstantFoldCompareInstOperands(Predicate, CE0->getOperand(1), Ops1,TD); |
| unsigned OpC = |
| Predicate == ICmpInst::ICMP_EQ ? Instruction::And : Instruction::Or; |
| Constant *Ops[] = { LHS, RHS }; |
| return ConstantFoldInstOperands(OpC, LHS->getType(), Ops, TD); |
| } |
| } |
| |
| return ConstantExpr::getCompare(Predicate, Ops0, Ops1); |
| } |
| |
| |
| /// ConstantFoldLoadThroughGEPConstantExpr - Given a constant and a |
| /// getelementptr constantexpr, return the constant value being addressed by the |
| /// constant expression, or null if something is funny and we can't decide. |
| Constant *llvm::ConstantFoldLoadThroughGEPConstantExpr(Constant *C, |
| ConstantExpr *CE) { |
| if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType())) |
| return 0; // Do not allow stepping over the value! |
| |
| // Loop over all of the operands, tracking down which value we are |
| // addressing... |
| gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE); |
| for (++I; I != E; ++I) |
| if (StructType *STy = dyn_cast<StructType>(*I)) { |
| ConstantInt *CU = cast<ConstantInt>(I.getOperand()); |
| assert(CU->getZExtValue() < STy->getNumElements() && |
| "Struct index out of range!"); |
| unsigned El = (unsigned)CU->getZExtValue(); |
| if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) { |
| C = CS->getOperand(El); |
| } else if (isa<ConstantAggregateZero>(C)) { |
| C = Constant::getNullValue(STy->getElementType(El)); |
| } else if (isa<UndefValue>(C)) { |
| C = UndefValue::get(STy->getElementType(El)); |
| } else { |
| return 0; |
| } |
| } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) { |
| if (ArrayType *ATy = dyn_cast<ArrayType>(*I)) { |
| if (CI->getZExtValue() >= ATy->getNumElements()) |
| return 0; |
| if (ConstantArray *CA = dyn_cast<ConstantArray>(C)) |
| C = CA->getOperand(CI->getZExtValue()); |
| else if (isa<ConstantAggregateZero>(C)) |
| C = Constant::getNullValue(ATy->getElementType()); |
| else if (isa<UndefValue>(C)) |
| C = UndefValue::get(ATy->getElementType()); |
| else |
| return 0; |
| } else if (VectorType *VTy = dyn_cast<VectorType>(*I)) { |
| if (CI->getZExtValue() >= VTy->getNumElements()) |
| return 0; |
| if (ConstantVector *CP = dyn_cast<ConstantVector>(C)) |
| C = CP->getOperand(CI->getZExtValue()); |
| else if (isa<ConstantAggregateZero>(C)) |
| C = Constant::getNullValue(VTy->getElementType()); |
| else if (isa<UndefValue>(C)) |
| C = UndefValue::get(VTy->getElementType()); |
| else |
| return 0; |
| } else { |
| return 0; |
| } |
| } else { |
| return 0; |
| } |
| return C; |
| } |
| |
| |
| //===----------------------------------------------------------------------===// |
| // Constant Folding for Calls |
| // |
| |
| /// canConstantFoldCallTo - Return true if its even possible to fold a call to |
| /// the specified function. |
| bool |
| llvm::canConstantFoldCallTo(const Function *F) { |
| switch (F->getIntrinsicID()) { |
| case Intrinsic::sqrt: |
| case Intrinsic::powi: |
| case Intrinsic::bswap: |
| case Intrinsic::ctpop: |
| case Intrinsic::ctlz: |
| case Intrinsic::cttz: |
| case Intrinsic::sadd_with_overflow: |
| case Intrinsic::uadd_with_overflow: |
| case Intrinsic::ssub_with_overflow: |
| case Intrinsic::usub_with_overflow: |
| case Intrinsic::smul_with_overflow: |
| case Intrinsic::umul_with_overflow: |
| case Intrinsic::convert_from_fp16: |
| case Intrinsic::convert_to_fp16: |
| case Intrinsic::x86_sse_cvtss2si: |
| case Intrinsic::x86_sse_cvtss2si64: |
| case Intrinsic::x86_sse_cvttss2si: |
| case Intrinsic::x86_sse_cvttss2si64: |
| case Intrinsic::x86_sse2_cvtsd2si: |
| case Intrinsic::x86_sse2_cvtsd2si64: |
| case Intrinsic::x86_sse2_cvttsd2si: |
| case Intrinsic::x86_sse2_cvttsd2si64: |
| return true; |
| default: |
| return false; |
| case 0: break; |
| } |
| |
| if (!F->hasName()) return false; |
| StringRef Name = F->getName(); |
| |
| // In these cases, the check of the length is required. We don't want to |
| // return true for a name like "cos\0blah" which strcmp would return equal to |
| // "cos", but has length 8. |
| switch (Name[0]) { |
| default: return false; |
| case 'a': |
| return Name == "acos" || Name == "asin" || |
| Name == "atan" || Name == "atan2"; |
| case 'c': |
| return Name == "cos" || Name == "ceil" || Name == "cosf" || Name == "cosh"; |
| case 'e': |
| return Name == "exp" || Name == "exp2"; |
| case 'f': |
| return Name == "fabs" || Name == "fmod" || Name == "floor"; |
| case 'l': |
| return Name == "log" || Name == "log10"; |
| case 'p': |
| return Name == "pow"; |
| case 's': |
| return Name == "sin" || Name == "sinh" || Name == "sqrt" || |
| Name == "sinf" || Name == "sqrtf"; |
| case 't': |
| return Name == "tan" || Name == "tanh"; |
| } |
| } |
| |
| static Constant *ConstantFoldFP(double (*NativeFP)(double), double V, |
| Type *Ty) { |
| sys::llvm_fenv_clearexcept(); |
| V = NativeFP(V); |
| if (sys::llvm_fenv_testexcept()) { |
| sys::llvm_fenv_clearexcept(); |
| return 0; |
| } |
| |
| if (Ty->isFloatTy()) |
| return ConstantFP::get(Ty->getContext(), APFloat((float)V)); |
| if (Ty->isDoubleTy()) |
| return ConstantFP::get(Ty->getContext(), APFloat(V)); |
| llvm_unreachable("Can only constant fold float/double"); |
| return 0; // dummy return to suppress warning |
| } |
| |
| static Constant *ConstantFoldBinaryFP(double (*NativeFP)(double, double), |
| double V, double W, Type *Ty) { |
| sys::llvm_fenv_clearexcept(); |
| V = NativeFP(V, W); |
| if (sys::llvm_fenv_testexcept()) { |
| sys::llvm_fenv_clearexcept(); |
| return 0; |
| } |
| |
| if (Ty->isFloatTy()) |
| return ConstantFP::get(Ty->getContext(), APFloat((float)V)); |
| if (Ty->isDoubleTy()) |
| return ConstantFP::get(Ty->getContext(), APFloat(V)); |
| llvm_unreachable("Can only constant fold float/double"); |
| return 0; // dummy return to suppress warning |
| } |
| |
| /// ConstantFoldConvertToInt - Attempt to an SSE floating point to integer |
| /// conversion of a constant floating point. If roundTowardZero is false, the |
| /// default IEEE rounding is used (toward nearest, ties to even). This matches |
| /// the behavior of the non-truncating SSE instructions in the default rounding |
| /// mode. The desired integer type Ty is used to select how many bits are |
| /// available for the result. Returns null if the conversion cannot be |
| /// performed, otherwise returns the Constant value resulting from the |
| /// conversion. |
| static Constant *ConstantFoldConvertToInt(ConstantFP *Op, bool roundTowardZero, |
| Type *Ty) { |
| assert(Op && "Called with NULL operand"); |
| APFloat Val(Op->getValueAPF()); |
| |
| // All of these conversion intrinsics form an integer of at most 64bits. |
| unsigned ResultWidth = cast<IntegerType>(Ty)->getBitWidth(); |
| assert(ResultWidth <= 64 && |
| "Can only constant fold conversions to 64 and 32 bit ints"); |
| |
| uint64_t UIntVal; |
| bool isExact = false; |
| APFloat::roundingMode mode = roundTowardZero? APFloat::rmTowardZero |
| : APFloat::rmNearestTiesToEven; |
| APFloat::opStatus status = Val.convertToInteger(&UIntVal, ResultWidth, |
| /*isSigned=*/true, mode, |
| &isExact); |
| if (status != APFloat::opOK && status != APFloat::opInexact) |
| return 0; |
| return ConstantInt::get(Ty, UIntVal, /*isSigned=*/true); |
| } |
| |
| /// ConstantFoldCall - Attempt to constant fold a call to the specified function |
| /// with the specified arguments, returning null if unsuccessful. |
| Constant * |
| llvm::ConstantFoldCall(Function *F, ArrayRef<Constant *> Operands) { |
| if (!F->hasName()) return 0; |
| StringRef Name = F->getName(); |
| |
| Type *Ty = F->getReturnType(); |
| if (Operands.size() == 1) { |
| if (ConstantFP *Op = dyn_cast<ConstantFP>(Operands[0])) { |
| if (F->getIntrinsicID() == Intrinsic::convert_to_fp16) { |
| APFloat Val(Op->getValueAPF()); |
| |
| bool lost = false; |
| Val.convert(APFloat::IEEEhalf, APFloat::rmNearestTiesToEven, &lost); |
| |
| return ConstantInt::get(F->getContext(), Val.bitcastToAPInt()); |
| } |
| |
| if (!Ty->isFloatTy() && !Ty->isDoubleTy()) |
| return 0; |
| |
| /// We only fold functions with finite arguments. Folding NaN and inf is |
| /// likely to be aborted with an exception anyway, and some host libms |
| /// have known errors raising exceptions. |
| if (Op->getValueAPF().isNaN() || Op->getValueAPF().isInfinity()) |
| return 0; |
| |
| /// Currently APFloat versions of these functions do not exist, so we use |
| /// the host native double versions. Float versions are not called |
| /// directly but for all these it is true (float)(f((double)arg)) == |
| /// f(arg). Long double not supported yet. |
| double V = Ty->isFloatTy() ? (double)Op->getValueAPF().convertToFloat() : |
| Op->getValueAPF().convertToDouble(); |
| switch (Name[0]) { |
| case 'a': |
| if (Name == "acos") |
| return ConstantFoldFP(acos, V, Ty); |
| else if (Name == "asin") |
| return ConstantFoldFP(asin, V, Ty); |
| else if (Name == "atan") |
| return ConstantFoldFP(atan, V, Ty); |
| break; |
| case 'c': |
| if (Name == "ceil") |
| return ConstantFoldFP(ceil, V, Ty); |
| else if (Name == "cos") |
| return ConstantFoldFP(cos, V, Ty); |
| else if (Name == "cosh") |
| return ConstantFoldFP(cosh, V, Ty); |
| else if (Name == "cosf") |
| return ConstantFoldFP(cos, V, Ty); |
| break; |
| case 'e': |
| if (Name == "exp") |
| return ConstantFoldFP(exp, V, Ty); |
| |
| if (Name == "exp2") { |
| // Constant fold exp2(x) as pow(2,x) in case the host doesn't have a |
| // C99 library. |
| return ConstantFoldBinaryFP(pow, 2.0, V, Ty); |
| } |
| break; |
| case 'f': |
| if (Name == "fabs") |
| return ConstantFoldFP(fabs, V, Ty); |
| else if (Name == "floor") |
| return ConstantFoldFP(floor, V, Ty); |
| break; |
| case 'l': |
| if (Name == "log" && V > 0) |
| return ConstantFoldFP(log, V, Ty); |
| else if (Name == "log10" && V > 0) |
| return ConstantFoldFP(log10, V, Ty); |
| else if (F->getIntrinsicID() == Intrinsic::sqrt && |
| (Ty->isFloatTy() || Ty->isDoubleTy())) { |
| if (V >= -0.0) |
| return ConstantFoldFP(sqrt, V, Ty); |
| else // Undefined |
| return Constant::getNullValue(Ty); |
| } |
| break; |
| case 's': |
| if (Name == "sin") |
| return ConstantFoldFP(sin, V, Ty); |
| else if (Name == "sinh") |
| return ConstantFoldFP(sinh, V, Ty); |
| else if (Name == "sqrt" && V >= 0) |
| return ConstantFoldFP(sqrt, V, Ty); |
| else if (Name == "sqrtf" && V >= 0) |
| return ConstantFoldFP(sqrt, V, Ty); |
| else if (Name == "sinf") |
| return ConstantFoldFP(sin, V, Ty); |
| break; |
| case 't': |
| if (Name == "tan") |
| return ConstantFoldFP(tan, V, Ty); |
| else if (Name == "tanh") |
| return ConstantFoldFP(tanh, V, Ty); |
| break; |
| default: |
| break; |
| } |
| return 0; |
| } |
| |
| if (ConstantInt *Op = dyn_cast<ConstantInt>(Operands[0])) { |
| switch (F->getIntrinsicID()) { |
| case Intrinsic::bswap: |
| return ConstantInt::get(F->getContext(), Op->getValue().byteSwap()); |
| case Intrinsic::ctpop: |
| return ConstantInt::get(Ty, Op->getValue().countPopulation()); |
| case Intrinsic::cttz: |
| return ConstantInt::get(Ty, Op->getValue().countTrailingZeros()); |
| case Intrinsic::ctlz: |
| return ConstantInt::get(Ty, Op->getValue().countLeadingZeros()); |
| case Intrinsic::convert_from_fp16: { |
| APFloat Val(Op->getValue()); |
| |
| bool lost = false; |
| APFloat::opStatus status = |
| Val.convert(APFloat::IEEEsingle, APFloat::rmNearestTiesToEven, &lost); |
| |
| // Conversion is always precise. |
| (void)status; |
| assert(status == APFloat::opOK && !lost && |
| "Precision lost during fp16 constfolding"); |
| |
| return ConstantFP::get(F->getContext(), Val); |
| } |
| default: |
| return 0; |
| } |
| } |
| |
| if (ConstantVector *Op = dyn_cast<ConstantVector>(Operands[0])) { |
| switch (F->getIntrinsicID()) { |
| default: break; |
| case Intrinsic::x86_sse_cvtss2si: |
| case Intrinsic::x86_sse_cvtss2si64: |
| case Intrinsic::x86_sse2_cvtsd2si: |
| case Intrinsic::x86_sse2_cvtsd2si64: |
| if (ConstantFP *FPOp = dyn_cast<ConstantFP>(Op->getOperand(0))) |
| return ConstantFoldConvertToInt(FPOp, /*roundTowardZero=*/false, Ty); |
| case Intrinsic::x86_sse_cvttss2si: |
| case Intrinsic::x86_sse_cvttss2si64: |
| case Intrinsic::x86_sse2_cvttsd2si: |
| case Intrinsic::x86_sse2_cvttsd2si64: |
| if (ConstantFP *FPOp = dyn_cast<ConstantFP>(Op->getOperand(0))) |
| return ConstantFoldConvertToInt(FPOp, /*roundTowardZero=*/true, Ty); |
| } |
| } |
| |
| if (isa<UndefValue>(Operands[0])) { |
| if (F->getIntrinsicID() == Intrinsic::bswap) |
| return Operands[0]; |
| return 0; |
| } |
| |
| return 0; |
| } |
| |
| if (Operands.size() == 2) { |
| if (ConstantFP *Op1 = dyn_cast<ConstantFP>(Operands[0])) { |
| if (!Ty->isFloatTy() && !Ty->isDoubleTy()) |
| return 0; |
| double Op1V = Ty->isFloatTy() ? |
| (double)Op1->getValueAPF().convertToFloat() : |
| Op1->getValueAPF().convertToDouble(); |
| if (ConstantFP *Op2 = dyn_cast<ConstantFP>(Operands[1])) { |
| if (Op2->getType() != Op1->getType()) |
| return 0; |
| |
| double Op2V = Ty->isFloatTy() ? |
| (double)Op2->getValueAPF().convertToFloat(): |
| Op2->getValueAPF().convertToDouble(); |
| |
| if (Name == "pow") |
| return ConstantFoldBinaryFP(pow, Op1V, Op2V, Ty); |
| if (Name == "fmod") |
| return ConstantFoldBinaryFP(fmod, Op1V, Op2V, Ty); |
| if (Name == "atan2") |
| return ConstantFoldBinaryFP(atan2, Op1V, Op2V, Ty); |
| } else if (ConstantInt *Op2C = dyn_cast<ConstantInt>(Operands[1])) { |
| if (F->getIntrinsicID() == Intrinsic::powi && Ty->isFloatTy()) |
| return ConstantFP::get(F->getContext(), |
| APFloat((float)std::pow((float)Op1V, |
| (int)Op2C->getZExtValue()))); |
| if (F->getIntrinsicID() == Intrinsic::powi && Ty->isDoubleTy()) |
| return ConstantFP::get(F->getContext(), |
| APFloat((double)std::pow((double)Op1V, |
| (int)Op2C->getZExtValue()))); |
| } |
| return 0; |
| } |
| |
| |
| if (ConstantInt *Op1 = dyn_cast<ConstantInt>(Operands[0])) { |
| if (ConstantInt *Op2 = dyn_cast<ConstantInt>(Operands[1])) { |
| switch (F->getIntrinsicID()) { |
| default: break; |
| case Intrinsic::sadd_with_overflow: |
| case Intrinsic::uadd_with_overflow: |
| case Intrinsic::ssub_with_overflow: |
| case Intrinsic::usub_with_overflow: |
| case Intrinsic::smul_with_overflow: |
| case Intrinsic::umul_with_overflow: { |
| APInt Res; |
| bool Overflow; |
| switch (F->getIntrinsicID()) { |
| default: assert(0 && "Invalid case"); |
| case Intrinsic::sadd_with_overflow: |
| Res = Op1->getValue().sadd_ov(Op2->getValue(), Overflow); |
| break; |
| case Intrinsic::uadd_with_overflow: |
| Res = Op1->getValue().uadd_ov(Op2->getValue(), Overflow); |
| break; |
| case Intrinsic::ssub_with_overflow: |
| Res = Op1->getValue().ssub_ov(Op2->getValue(), Overflow); |
| break; |
| case Intrinsic::usub_with_overflow: |
| Res = Op1->getValue().usub_ov(Op2->getValue(), Overflow); |
| break; |
| case Intrinsic::smul_with_overflow: |
| Res = Op1->getValue().smul_ov(Op2->getValue(), Overflow); |
| break; |
| case Intrinsic::umul_with_overflow: |
| Res = Op1->getValue().umul_ov(Op2->getValue(), Overflow); |
| break; |
| } |
| Constant *Ops[] = { |
| ConstantInt::get(F->getContext(), Res), |
| ConstantInt::get(Type::getInt1Ty(F->getContext()), Overflow) |
| }; |
| return ConstantStruct::get(cast<StructType>(F->getReturnType()), Ops); |
| } |
| } |
| } |
| |
| return 0; |
| } |
| return 0; |
| } |
| return 0; |
| } |