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Diffstat (limited to 'contrib/llvm/lib/Analysis/ConstantFolding.cpp')
| -rw-r--r-- | contrib/llvm/lib/Analysis/ConstantFolding.cpp | 1282 |
1 files changed, 1282 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Analysis/ConstantFolding.cpp b/contrib/llvm/lib/Analysis/ConstantFolding.cpp new file mode 100644 index 0000000..37cda02 --- /dev/null +++ b/contrib/llvm/lib/Analysis/ConstantFolding.cpp @@ -0,0 +1,1282 @@ +//===-- 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/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 <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, const Type *DestTy, + const TargetData &TD) { + + // This only handles casts to vectors currently. + const 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, 1), 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); + + const Type *SrcEltTy = CV->getType()->getElementType(); + const 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(); + const 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(); + const 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.data(), Result.size()); +} + + +/// 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->getZExtValue() == 0) continue; // Not adding anything. + + if (const StructType *ST = dyn_cast<StructType>(*GTI)) { + // N = N + Offset + Offset += TD.getStructLayout(ST)->getElementOffset(CI->getZExtValue()); + } else { + const 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; + } + + // Otherwise, unknown initializer type. + return false; +} + +static Constant *FoldReinterpretLoadFromConstPtr(Constant *C, + const TargetData &TD) { + const Type *LoadTy = cast<PointerType>(C->getType())->getElementType(); + const 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. + const 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(); + const Type *Ty = cast<PointerType>(CE->getType())->getElementType(); + unsigned NumBits = Ty->getPrimitiveSizeInBits(); + // Replace LI with immediate integer store. + if ((NumBits >> 3) == StrLen + 1) { + 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; + } + return ConstantInt::get(CE->getContext(), StrVal); + } + } + + // 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>(CE->getUnderlyingObject())){ + if (GV->isConstant() && GV->hasDefinitiveInitializer()) { + const 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(Constant *const *Ops, unsigned NumOps, + const Type *ResultTy, + const TargetData *TD) { + if (!TD) return 0; + const Type *IntPtrTy = TD->getIntPtrType(ResultTy->getContext()); + + bool Any = false; + SmallVector<Constant*, 32> NewIdxs; + for (unsigned i = 1; i != NumOps; ++i) { + if ((i == 1 || + !isa<StructType>(GetElementPtrInst::getIndexedType(Ops[0]->getType(), + reinterpret_cast<Value *const *>(Ops+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[0], NewIdxs.size()); + 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(Constant *const *Ops, unsigned NumOps, + const Type *ResultTy, + const TargetData *TD) { + Constant *Ptr = Ops[0]; + if (!TD || !cast<PointerType>(Ptr->getType())->getElementType()->isSized()) + return 0; + + unsigned BitWidth = + TD->getTypeSizeInBits(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; i != NumOps; ++i) + if (!isa<ConstantInt>(Ops[i])) + return 0; + + APInt Offset = APInt(BitWidth, + TD->getIndexedOffset(Ptr->getType(), + (Value**)Ops+1, NumOps-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(), + (Value**)NestedOps.data(), + NestedOps.size())); + 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(); + BasePtr.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. + const Type *Ty = Ptr->getType(); + SmallVector<Constant*, 32> NewIdxs; + do { + if (const 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())); + if (ElemSize == 0) + return 0; + APInt NewIdx = Offset.udiv(ElemSize); + Offset -= NewIdx * ElemSize; + NewIdxs.push_back(ConstantInt::get(TD->getIntPtrType(Ty->getContext()), + NewIdx)); + Ty = ATy->getElementType(); + } else if (const 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[0], NewIdxs.size()); + 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 - Attempt to constant fold the specified +/// instruction. If successful, the constant result is returned, if not, null +/// is returned. Note that 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) { + if (PHINode *PN = dyn_cast<PHINode>(I)) { + if (PN->getNumIncomingValues() == 0) + return UndefValue::get(PN->getType()); + + Constant *Result = dyn_cast<Constant>(PN->getIncomingValue(0)); + if (Result == 0) return 0; + + // Handle PHI nodes specially here... + for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) + if (PN->getIncomingValue(i) != Result && PN->getIncomingValue(i) != PN) + return 0; // Not all the same incoming constants... + + // If we reach here, all incoming values are the same constant. + return Result; + } + + // 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); + + return ConstantFoldInstOperands(I->getOpcode(), I->getType(), + Ops.data(), Ops.size(), 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.data(), Ops.size(), 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, const Type *DestTy, + Constant* const* Ops, unsigned NumOps, + 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[0])) + if (canConstantFoldCallTo(F)) + return ConstantFoldCall(F, Ops+1, NumOps-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, NumOps, DestTy, TD)) + return C; + if (Constant *C = SymbolicallyEvaluateGEP(Ops, NumOps, DestTy, TD)) + return C; + + return ConstantExpr::getGetElementPtr(Ops[0], Ops+1, NumOps-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()) { + const 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()) { + const 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, 2, 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 (const 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 (const 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 (const 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::uadd_with_overflow: + case Intrinsic::usub_with_overflow: + case Intrinsic::sadd_with_overflow: + case Intrinsic::ssub_with_overflow: + case Intrinsic::convert_from_fp16: + case Intrinsic::convert_to_fp16: + 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"; + 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, + const Type *Ty) { + errno = 0; + V = NativeFP(V); + if (errno != 0) { + errno = 0; + 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, const Type *Ty) { + errno = 0; + V = NativeFP(V, W); + if (errno != 0) { + errno = 0; + 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 +} + +/// ConstantFoldCall - Attempt to constant fold a call to the specified function +/// with the specified arguments, returning null if unsuccessful. +Constant * +llvm::ConstantFoldCall(Function *F, + Constant *const *Operands, unsigned NumOperands) { + if (!F->hasName()) return 0; + StringRef Name = F->getName(); + + const Type *Ty = F->getReturnType(); + if (NumOperands == 1) { + if (ConstantFP *Op = dyn_cast<ConstantFP>(Operands[0])) { + if (Name == "llvm.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; + /// 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); + 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 (Name == "llvm.sqrt.f32" || + Name == "llvm.sqrt.f64") { + 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])) { + if (Name.startswith("llvm.bswap")) + return ConstantInt::get(F->getContext(), Op->getValue().byteSwap()); + else if (Name.startswith("llvm.ctpop")) + return ConstantInt::get(Ty, Op->getValue().countPopulation()); + else if (Name.startswith("llvm.cttz")) + return ConstantInt::get(Ty, Op->getValue().countTrailingZeros()); + else if (Name.startswith("llvm.ctlz")) + return ConstantInt::get(Ty, Op->getValue().countLeadingZeros()); + else if (Name == "llvm.convert.from.fp16") { + APFloat Val(Op->getValue()); + + bool lost = false; + APFloat::opStatus status = + Val.convert(APFloat::IEEEsingle, APFloat::rmNearestTiesToEven, &lost); + + // Conversion is always precise. + status = status; + assert(status == APFloat::opOK && !lost && + "Precision lost during fp16 constfolding"); + + return ConstantFP::get(F->getContext(), Val); + } + return 0; + } + + if (isa<UndefValue>(Operands[0])) { + if (Name.startswith("llvm.bswap")) + return Operands[0]; + return 0; + } + + return 0; + } + + if (NumOperands == 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 (Name == "llvm.powi.f32") + return ConstantFP::get(F->getContext(), + APFloat((float)std::pow((float)Op1V, + (int)Op2C->getZExtValue()))); + if (Name == "llvm.powi.f64") + 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::uadd_with_overflow: { + Constant *Res = ConstantExpr::getAdd(Op1, Op2); // result. + Constant *Ops[] = { + Res, ConstantExpr::getICmp(CmpInst::ICMP_ULT, Res, Op1) // overflow. + }; + return ConstantStruct::get(F->getContext(), Ops, 2, false); + } + case Intrinsic::usub_with_overflow: { + Constant *Res = ConstantExpr::getSub(Op1, Op2); // result. + Constant *Ops[] = { + Res, ConstantExpr::getICmp(CmpInst::ICMP_UGT, Res, Op1) // overflow. + }; + return ConstantStruct::get(F->getContext(), Ops, 2, false); + } + case Intrinsic::sadd_with_overflow: { + Constant *Res = ConstantExpr::getAdd(Op1, Op2); // result. + Constant *Overflow = ConstantExpr::getSelect( + ConstantExpr::getICmp(CmpInst::ICMP_SGT, + ConstantInt::get(Op1->getType(), 0), Op1), + ConstantExpr::getICmp(CmpInst::ICMP_SGT, Res, Op2), + ConstantExpr::getICmp(CmpInst::ICMP_SLT, Res, Op2)); // overflow. + + Constant *Ops[] = { Res, Overflow }; + return ConstantStruct::get(F->getContext(), Ops, 2, false); + } + case Intrinsic::ssub_with_overflow: { + Constant *Res = ConstantExpr::getSub(Op1, Op2); // result. + Constant *Overflow = ConstantExpr::getSelect( + ConstantExpr::getICmp(CmpInst::ICMP_SGT, + ConstantInt::get(Op2->getType(), 0), Op2), + ConstantExpr::getICmp(CmpInst::ICMP_SLT, Res, Op1), + ConstantExpr::getICmp(CmpInst::ICMP_SGT, Res, Op1)); // overflow. + + Constant *Ops[] = { Res, Overflow }; + return ConstantStruct::get(F->getContext(), Ops, 2, false); + } + } + } + + return 0; + } + return 0; + } + return 0; +} + |
