diff options
Diffstat (limited to 'contrib/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp')
| -rw-r--r-- | contrib/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp | 2458 |
1 files changed, 0 insertions, 2458 deletions
diff --git a/contrib/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/contrib/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp deleted file mode 100644 index 2c9ba203fbf3..000000000000 --- a/contrib/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp +++ /dev/null @@ -1,2458 +0,0 @@ -//===- InstCombineCasts.cpp -----------------------------------------------===// -// -// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. -// See https://llvm.org/LICENSE.txt for license information. -// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception -// -//===----------------------------------------------------------------------===// -// -// This file implements the visit functions for cast operations. -// -//===----------------------------------------------------------------------===// - -#include "InstCombineInternal.h" -#include "llvm/ADT/SetVector.h" -#include "llvm/Analysis/ConstantFolding.h" -#include "llvm/Analysis/TargetLibraryInfo.h" -#include "llvm/IR/DataLayout.h" -#include "llvm/IR/DIBuilder.h" -#include "llvm/IR/PatternMatch.h" -#include "llvm/Support/KnownBits.h" -using namespace llvm; -using namespace PatternMatch; - -#define DEBUG_TYPE "instcombine" - -/// Analyze 'Val', seeing if it is a simple linear expression. -/// If so, decompose it, returning some value X, such that Val is -/// X*Scale+Offset. -/// -static Value *decomposeSimpleLinearExpr(Value *Val, unsigned &Scale, - uint64_t &Offset) { - if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) { - Offset = CI->getZExtValue(); - Scale = 0; - return ConstantInt::get(Val->getType(), 0); - } - - if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) { - // Cannot look past anything that might overflow. - OverflowingBinaryOperator *OBI = dyn_cast<OverflowingBinaryOperator>(Val); - if (OBI && !OBI->hasNoUnsignedWrap() && !OBI->hasNoSignedWrap()) { - Scale = 1; - Offset = 0; - return Val; - } - - if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) { - if (I->getOpcode() == Instruction::Shl) { - // This is a value scaled by '1 << the shift amt'. - Scale = UINT64_C(1) << RHS->getZExtValue(); - Offset = 0; - return I->getOperand(0); - } - - if (I->getOpcode() == Instruction::Mul) { - // This value is scaled by 'RHS'. - Scale = RHS->getZExtValue(); - Offset = 0; - return I->getOperand(0); - } - - if (I->getOpcode() == Instruction::Add) { - // We have X+C. Check to see if we really have (X*C2)+C1, - // where C1 is divisible by C2. - unsigned SubScale; - Value *SubVal = - decomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset); - Offset += RHS->getZExtValue(); - Scale = SubScale; - return SubVal; - } - } - } - - // Otherwise, we can't look past this. - Scale = 1; - Offset = 0; - return Val; -} - -/// If we find a cast of an allocation instruction, try to eliminate the cast by -/// moving the type information into the alloc. -Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI, - AllocaInst &AI) { - PointerType *PTy = cast<PointerType>(CI.getType()); - - BuilderTy AllocaBuilder(Builder); - AllocaBuilder.SetInsertPoint(&AI); - - // Get the type really allocated and the type casted to. - Type *AllocElTy = AI.getAllocatedType(); - Type *CastElTy = PTy->getElementType(); - if (!AllocElTy->isSized() || !CastElTy->isSized()) return nullptr; - - unsigned AllocElTyAlign = DL.getABITypeAlignment(AllocElTy); - unsigned CastElTyAlign = DL.getABITypeAlignment(CastElTy); - if (CastElTyAlign < AllocElTyAlign) return nullptr; - - // If the allocation has multiple uses, only promote it if we are strictly - // increasing the alignment of the resultant allocation. If we keep it the - // same, we open the door to infinite loops of various kinds. - if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return nullptr; - - uint64_t AllocElTySize = DL.getTypeAllocSize(AllocElTy); - uint64_t CastElTySize = DL.getTypeAllocSize(CastElTy); - if (CastElTySize == 0 || AllocElTySize == 0) return nullptr; - - // If the allocation has multiple uses, only promote it if we're not - // shrinking the amount of memory being allocated. - uint64_t AllocElTyStoreSize = DL.getTypeStoreSize(AllocElTy); - uint64_t CastElTyStoreSize = DL.getTypeStoreSize(CastElTy); - if (!AI.hasOneUse() && CastElTyStoreSize < AllocElTyStoreSize) return nullptr; - - // See if we can satisfy the modulus by pulling a scale out of the array - // size argument. - unsigned ArraySizeScale; - uint64_t ArrayOffset; - Value *NumElements = // See if the array size is a decomposable linear expr. - decomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset); - - // If we can now satisfy the modulus, by using a non-1 scale, we really can - // do the xform. - if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 || - (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return nullptr; - - unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize; - Value *Amt = nullptr; - if (Scale == 1) { - Amt = NumElements; - } else { - Amt = ConstantInt::get(AI.getArraySize()->getType(), Scale); - // Insert before the alloca, not before the cast. - Amt = AllocaBuilder.CreateMul(Amt, NumElements); - } - - if (uint64_t Offset = (AllocElTySize*ArrayOffset)/CastElTySize) { - Value *Off = ConstantInt::get(AI.getArraySize()->getType(), - Offset, true); - Amt = AllocaBuilder.CreateAdd(Amt, Off); - } - - AllocaInst *New = AllocaBuilder.CreateAlloca(CastElTy, Amt); - New->setAlignment(AI.getAlignment()); - New->takeName(&AI); - New->setUsedWithInAlloca(AI.isUsedWithInAlloca()); - - // If the allocation has multiple real uses, insert a cast and change all - // things that used it to use the new cast. This will also hack on CI, but it - // will die soon. - if (!AI.hasOneUse()) { - // New is the allocation instruction, pointer typed. AI is the original - // allocation instruction, also pointer typed. Thus, cast to use is BitCast. - Value *NewCast = AllocaBuilder.CreateBitCast(New, AI.getType(), "tmpcast"); - replaceInstUsesWith(AI, NewCast); - } - return replaceInstUsesWith(CI, New); -} - -/// Given an expression that CanEvaluateTruncated or CanEvaluateSExtd returns -/// true for, actually insert the code to evaluate the expression. -Value *InstCombiner::EvaluateInDifferentType(Value *V, Type *Ty, - bool isSigned) { - if (Constant *C = dyn_cast<Constant>(V)) { - C = ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/); - // If we got a constantexpr back, try to simplify it with DL info. - if (Constant *FoldedC = ConstantFoldConstant(C, DL, &TLI)) - C = FoldedC; - return C; - } - - // Otherwise, it must be an instruction. - Instruction *I = cast<Instruction>(V); - Instruction *Res = nullptr; - unsigned Opc = I->getOpcode(); - switch (Opc) { - case Instruction::Add: - case Instruction::Sub: - case Instruction::Mul: - case Instruction::And: - case Instruction::Or: - case Instruction::Xor: - case Instruction::AShr: - case Instruction::LShr: - case Instruction::Shl: - case Instruction::UDiv: - case Instruction::URem: { - Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned); - Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned); - Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS); - break; - } - case Instruction::Trunc: - case Instruction::ZExt: - case Instruction::SExt: - // If the source type of the cast is the type we're trying for then we can - // just return the source. There's no need to insert it because it is not - // new. - if (I->getOperand(0)->getType() == Ty) - return I->getOperand(0); - - // Otherwise, must be the same type of cast, so just reinsert a new one. - // This also handles the case of zext(trunc(x)) -> zext(x). - Res = CastInst::CreateIntegerCast(I->getOperand(0), Ty, - Opc == Instruction::SExt); - break; - case Instruction::Select: { - Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned); - Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned); - Res = SelectInst::Create(I->getOperand(0), True, False); - break; - } - case Instruction::PHI: { - PHINode *OPN = cast<PHINode>(I); - PHINode *NPN = PHINode::Create(Ty, OPN->getNumIncomingValues()); - for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) { - Value *V = - EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned); - NPN->addIncoming(V, OPN->getIncomingBlock(i)); - } - Res = NPN; - break; - } - default: - // TODO: Can handle more cases here. - llvm_unreachable("Unreachable!"); - } - - Res->takeName(I); - return InsertNewInstWith(Res, *I); -} - -Instruction::CastOps InstCombiner::isEliminableCastPair(const CastInst *CI1, - const CastInst *CI2) { - Type *SrcTy = CI1->getSrcTy(); - Type *MidTy = CI1->getDestTy(); - Type *DstTy = CI2->getDestTy(); - - Instruction::CastOps firstOp = CI1->getOpcode(); - Instruction::CastOps secondOp = CI2->getOpcode(); - Type *SrcIntPtrTy = - SrcTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(SrcTy) : nullptr; - Type *MidIntPtrTy = - MidTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(MidTy) : nullptr; - Type *DstIntPtrTy = - DstTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(DstTy) : nullptr; - unsigned Res = CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, - DstTy, SrcIntPtrTy, MidIntPtrTy, - DstIntPtrTy); - - // We don't want to form an inttoptr or ptrtoint that converts to an integer - // type that differs from the pointer size. - if ((Res == Instruction::IntToPtr && SrcTy != DstIntPtrTy) || - (Res == Instruction::PtrToInt && DstTy != SrcIntPtrTy)) - Res = 0; - - return Instruction::CastOps(Res); -} - -/// Implement the transforms common to all CastInst visitors. -Instruction *InstCombiner::commonCastTransforms(CastInst &CI) { - Value *Src = CI.getOperand(0); - - // Try to eliminate a cast of a cast. - if (auto *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast - if (Instruction::CastOps NewOpc = isEliminableCastPair(CSrc, &CI)) { - // The first cast (CSrc) is eliminable so we need to fix up or replace - // the second cast (CI). CSrc will then have a good chance of being dead. - auto *Ty = CI.getType(); - auto *Res = CastInst::Create(NewOpc, CSrc->getOperand(0), Ty); - // Point debug users of the dying cast to the new one. - if (CSrc->hasOneUse()) - replaceAllDbgUsesWith(*CSrc, *Res, CI, DT); - return Res; - } - } - - if (auto *Sel = dyn_cast<SelectInst>(Src)) { - // We are casting a select. Try to fold the cast into the select, but only - // if the select does not have a compare instruction with matching operand - // types. Creating a select with operands that are different sizes than its - // condition may inhibit other folds and lead to worse codegen. - auto *Cmp = dyn_cast<CmpInst>(Sel->getCondition()); - if (!Cmp || Cmp->getOperand(0)->getType() != Sel->getType()) - if (Instruction *NV = FoldOpIntoSelect(CI, Sel)) { - replaceAllDbgUsesWith(*Sel, *NV, CI, DT); - return NV; - } - } - - // If we are casting a PHI, then fold the cast into the PHI. - if (auto *PN = dyn_cast<PHINode>(Src)) { - // Don't do this if it would create a PHI node with an illegal type from a - // legal type. - if (!Src->getType()->isIntegerTy() || !CI.getType()->isIntegerTy() || - shouldChangeType(CI.getType(), Src->getType())) - if (Instruction *NV = foldOpIntoPhi(CI, PN)) - return NV; - } - - return nullptr; -} - -/// Constants and extensions/truncates from the destination type are always -/// free to be evaluated in that type. This is a helper for canEvaluate*. -static bool canAlwaysEvaluateInType(Value *V, Type *Ty) { - if (isa<Constant>(V)) - return true; - Value *X; - if ((match(V, m_ZExtOrSExt(m_Value(X))) || match(V, m_Trunc(m_Value(X)))) && - X->getType() == Ty) - return true; - - return false; -} - -/// Filter out values that we can not evaluate in the destination type for free. -/// This is a helper for canEvaluate*. -static bool canNotEvaluateInType(Value *V, Type *Ty) { - assert(!isa<Constant>(V) && "Constant should already be handled."); - if (!isa<Instruction>(V)) - return true; - // We don't extend or shrink something that has multiple uses -- doing so - // would require duplicating the instruction which isn't profitable. - if (!V->hasOneUse()) - return true; - - return false; -} - -/// Return true if we can evaluate the specified expression tree as type Ty -/// instead of its larger type, and arrive with the same value. -/// This is used by code that tries to eliminate truncates. -/// -/// Ty will always be a type smaller than V. We should return true if trunc(V) -/// can be computed by computing V in the smaller type. If V is an instruction, -/// then trunc(inst(x,y)) can be computed as inst(trunc(x),trunc(y)), which only -/// makes sense if x and y can be efficiently truncated. -/// -/// This function works on both vectors and scalars. -/// -static bool canEvaluateTruncated(Value *V, Type *Ty, InstCombiner &IC, - Instruction *CxtI) { - if (canAlwaysEvaluateInType(V, Ty)) - return true; - if (canNotEvaluateInType(V, Ty)) - return false; - - auto *I = cast<Instruction>(V); - Type *OrigTy = V->getType(); - switch (I->getOpcode()) { - case Instruction::Add: - case Instruction::Sub: - case Instruction::Mul: - case Instruction::And: - case Instruction::Or: - case Instruction::Xor: - // These operators can all arbitrarily be extended or truncated. - return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI) && - canEvaluateTruncated(I->getOperand(1), Ty, IC, CxtI); - - case Instruction::UDiv: - case Instruction::URem: { - // UDiv and URem can be truncated if all the truncated bits are zero. - uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits(); - uint32_t BitWidth = Ty->getScalarSizeInBits(); - assert(BitWidth < OrigBitWidth && "Unexpected bitwidths!"); - APInt Mask = APInt::getBitsSetFrom(OrigBitWidth, BitWidth); - if (IC.MaskedValueIsZero(I->getOperand(0), Mask, 0, CxtI) && - IC.MaskedValueIsZero(I->getOperand(1), Mask, 0, CxtI)) { - return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI) && - canEvaluateTruncated(I->getOperand(1), Ty, IC, CxtI); - } - break; - } - case Instruction::Shl: { - // If we are truncating the result of this SHL, and if it's a shift of a - // constant amount, we can always perform a SHL in a smaller type. - const APInt *Amt; - if (match(I->getOperand(1), m_APInt(Amt))) { - uint32_t BitWidth = Ty->getScalarSizeInBits(); - if (Amt->getLimitedValue(BitWidth) < BitWidth) - return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI); - } - break; - } - case Instruction::LShr: { - // If this is a truncate of a logical shr, we can truncate it to a smaller - // lshr iff we know that the bits we would otherwise be shifting in are - // already zeros. - const APInt *Amt; - if (match(I->getOperand(1), m_APInt(Amt))) { - uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits(); - uint32_t BitWidth = Ty->getScalarSizeInBits(); - if (Amt->getLimitedValue(BitWidth) < BitWidth && - IC.MaskedValueIsZero(I->getOperand(0), - APInt::getBitsSetFrom(OrigBitWidth, BitWidth), 0, CxtI)) { - return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI); - } - } - break; - } - case Instruction::AShr: { - // If this is a truncate of an arithmetic shr, we can truncate it to a - // smaller ashr iff we know that all the bits from the sign bit of the - // original type and the sign bit of the truncate type are similar. - // TODO: It is enough to check that the bits we would be shifting in are - // similar to sign bit of the truncate type. - const APInt *Amt; - if (match(I->getOperand(1), m_APInt(Amt))) { - uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits(); - uint32_t BitWidth = Ty->getScalarSizeInBits(); - if (Amt->getLimitedValue(BitWidth) < BitWidth && - OrigBitWidth - BitWidth < - IC.ComputeNumSignBits(I->getOperand(0), 0, CxtI)) - return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI); - } - break; - } - case Instruction::Trunc: - // trunc(trunc(x)) -> trunc(x) - return true; - case Instruction::ZExt: - case Instruction::SExt: - // trunc(ext(x)) -> ext(x) if the source type is smaller than the new dest - // trunc(ext(x)) -> trunc(x) if the source type is larger than the new dest - return true; - case Instruction::Select: { - SelectInst *SI = cast<SelectInst>(I); - return canEvaluateTruncated(SI->getTrueValue(), Ty, IC, CxtI) && - canEvaluateTruncated(SI->getFalseValue(), Ty, IC, CxtI); - } - case Instruction::PHI: { - // We can change a phi if we can change all operands. Note that we never - // get into trouble with cyclic PHIs here because we only consider - // instructions with a single use. - PHINode *PN = cast<PHINode>(I); - for (Value *IncValue : PN->incoming_values()) - if (!canEvaluateTruncated(IncValue, Ty, IC, CxtI)) - return false; - return true; - } - default: - // TODO: Can handle more cases here. - break; - } - - return false; -} - -/// Given a vector that is bitcast to an integer, optionally logically -/// right-shifted, and truncated, convert it to an extractelement. -/// Example (big endian): -/// trunc (lshr (bitcast <4 x i32> %X to i128), 32) to i32 -/// ---> -/// extractelement <4 x i32> %X, 1 -static Instruction *foldVecTruncToExtElt(TruncInst &Trunc, InstCombiner &IC) { - Value *TruncOp = Trunc.getOperand(0); - Type *DestType = Trunc.getType(); - if (!TruncOp->hasOneUse() || !isa<IntegerType>(DestType)) - return nullptr; - - Value *VecInput = nullptr; - ConstantInt *ShiftVal = nullptr; - if (!match(TruncOp, m_CombineOr(m_BitCast(m_Value(VecInput)), - m_LShr(m_BitCast(m_Value(VecInput)), - m_ConstantInt(ShiftVal)))) || - !isa<VectorType>(VecInput->getType())) - return nullptr; - - VectorType *VecType = cast<VectorType>(VecInput->getType()); - unsigned VecWidth = VecType->getPrimitiveSizeInBits(); - unsigned DestWidth = DestType->getPrimitiveSizeInBits(); - unsigned ShiftAmount = ShiftVal ? ShiftVal->getZExtValue() : 0; - - if ((VecWidth % DestWidth != 0) || (ShiftAmount % DestWidth != 0)) - return nullptr; - - // If the element type of the vector doesn't match the result type, - // bitcast it to a vector type that we can extract from. - unsigned NumVecElts = VecWidth / DestWidth; - if (VecType->getElementType() != DestType) { - VecType = VectorType::get(DestType, NumVecElts); - VecInput = IC.Builder.CreateBitCast(VecInput, VecType, "bc"); - } - - unsigned Elt = ShiftAmount / DestWidth; - if (IC.getDataLayout().isBigEndian()) - Elt = NumVecElts - 1 - Elt; - - return ExtractElementInst::Create(VecInput, IC.Builder.getInt32(Elt)); -} - -/// Rotate left/right may occur in a wider type than necessary because of type -/// promotion rules. Try to narrow the inputs and convert to funnel shift. -Instruction *InstCombiner::narrowRotate(TruncInst &Trunc) { - assert((isa<VectorType>(Trunc.getSrcTy()) || - shouldChangeType(Trunc.getSrcTy(), Trunc.getType())) && - "Don't narrow to an illegal scalar type"); - - // Bail out on strange types. It is possible to handle some of these patterns - // even with non-power-of-2 sizes, but it is not a likely scenario. - Type *DestTy = Trunc.getType(); - unsigned NarrowWidth = DestTy->getScalarSizeInBits(); - if (!isPowerOf2_32(NarrowWidth)) - return nullptr; - - // First, find an or'd pair of opposite shifts with the same shifted operand: - // trunc (or (lshr ShVal, ShAmt0), (shl ShVal, ShAmt1)) - Value *Or0, *Or1; - if (!match(Trunc.getOperand(0), m_OneUse(m_Or(m_Value(Or0), m_Value(Or1))))) - return nullptr; - - Value *ShVal, *ShAmt0, *ShAmt1; - if (!match(Or0, m_OneUse(m_LogicalShift(m_Value(ShVal), m_Value(ShAmt0)))) || - !match(Or1, m_OneUse(m_LogicalShift(m_Specific(ShVal), m_Value(ShAmt1))))) - return nullptr; - - auto ShiftOpcode0 = cast<BinaryOperator>(Or0)->getOpcode(); - auto ShiftOpcode1 = cast<BinaryOperator>(Or1)->getOpcode(); - if (ShiftOpcode0 == ShiftOpcode1) - return nullptr; - - // Match the shift amount operands for a rotate pattern. This always matches - // a subtraction on the R operand. - auto matchShiftAmount = [](Value *L, Value *R, unsigned Width) -> Value * { - // The shift amounts may add up to the narrow bit width: - // (shl ShVal, L) | (lshr ShVal, Width - L) - if (match(R, m_OneUse(m_Sub(m_SpecificInt(Width), m_Specific(L))))) - return L; - - // The shift amount may be masked with negation: - // (shl ShVal, (X & (Width - 1))) | (lshr ShVal, ((-X) & (Width - 1))) - Value *X; - unsigned Mask = Width - 1; - if (match(L, m_And(m_Value(X), m_SpecificInt(Mask))) && - match(R, m_And(m_Neg(m_Specific(X)), m_SpecificInt(Mask)))) - return X; - - // Same as above, but the shift amount may be extended after masking: - if (match(L, m_ZExt(m_And(m_Value(X), m_SpecificInt(Mask)))) && - match(R, m_ZExt(m_And(m_Neg(m_Specific(X)), m_SpecificInt(Mask))))) - return X; - - return nullptr; - }; - - Value *ShAmt = matchShiftAmount(ShAmt0, ShAmt1, NarrowWidth); - bool SubIsOnLHS = false; - if (!ShAmt) { - ShAmt = matchShiftAmount(ShAmt1, ShAmt0, NarrowWidth); - SubIsOnLHS = true; - } - if (!ShAmt) - return nullptr; - - // The shifted value must have high zeros in the wide type. Typically, this - // will be a zext, but it could also be the result of an 'and' or 'shift'. - unsigned WideWidth = Trunc.getSrcTy()->getScalarSizeInBits(); - APInt HiBitMask = APInt::getHighBitsSet(WideWidth, WideWidth - NarrowWidth); - if (!MaskedValueIsZero(ShVal, HiBitMask, 0, &Trunc)) - return nullptr; - - // We have an unnecessarily wide rotate! - // trunc (or (lshr ShVal, ShAmt), (shl ShVal, BitWidth - ShAmt)) - // Narrow the inputs and convert to funnel shift intrinsic: - // llvm.fshl.i8(trunc(ShVal), trunc(ShVal), trunc(ShAmt)) - Value *NarrowShAmt = Builder.CreateTrunc(ShAmt, DestTy); - Value *X = Builder.CreateTrunc(ShVal, DestTy); - bool IsFshl = (!SubIsOnLHS && ShiftOpcode0 == BinaryOperator::Shl) || - (SubIsOnLHS && ShiftOpcode1 == BinaryOperator::Shl); - Intrinsic::ID IID = IsFshl ? Intrinsic::fshl : Intrinsic::fshr; - Function *F = Intrinsic::getDeclaration(Trunc.getModule(), IID, DestTy); - return IntrinsicInst::Create(F, { X, X, NarrowShAmt }); -} - -/// Try to narrow the width of math or bitwise logic instructions by pulling a -/// truncate ahead of binary operators. -/// TODO: Transforms for truncated shifts should be moved into here. -Instruction *InstCombiner::narrowBinOp(TruncInst &Trunc) { - Type *SrcTy = Trunc.getSrcTy(); - Type *DestTy = Trunc.getType(); - if (!isa<VectorType>(SrcTy) && !shouldChangeType(SrcTy, DestTy)) - return nullptr; - - BinaryOperator *BinOp; - if (!match(Trunc.getOperand(0), m_OneUse(m_BinOp(BinOp)))) - return nullptr; - - Value *BinOp0 = BinOp->getOperand(0); - Value *BinOp1 = BinOp->getOperand(1); - switch (BinOp->getOpcode()) { - case Instruction::And: - case Instruction::Or: - case Instruction::Xor: - case Instruction::Add: - case Instruction::Sub: - case Instruction::Mul: { - Constant *C; - if (match(BinOp0, m_Constant(C))) { - // trunc (binop C, X) --> binop (trunc C', X) - Constant *NarrowC = ConstantExpr::getTrunc(C, DestTy); - Value *TruncX = Builder.CreateTrunc(BinOp1, DestTy); - return BinaryOperator::Create(BinOp->getOpcode(), NarrowC, TruncX); - } - if (match(BinOp1, m_Constant(C))) { - // trunc (binop X, C) --> binop (trunc X, C') - Constant *NarrowC = ConstantExpr::getTrunc(C, DestTy); - Value *TruncX = Builder.CreateTrunc(BinOp0, DestTy); - return BinaryOperator::Create(BinOp->getOpcode(), TruncX, NarrowC); - } - Value *X; - if (match(BinOp0, m_ZExtOrSExt(m_Value(X))) && X->getType() == DestTy) { - // trunc (binop (ext X), Y) --> binop X, (trunc Y) - Value *NarrowOp1 = Builder.CreateTrunc(BinOp1, DestTy); - return BinaryOperator::Create(BinOp->getOpcode(), X, NarrowOp1); - } - if (match(BinOp1, m_ZExtOrSExt(m_Value(X))) && X->getType() == DestTy) { - // trunc (binop Y, (ext X)) --> binop (trunc Y), X - Value *NarrowOp0 = Builder.CreateTrunc(BinOp0, DestTy); - return BinaryOperator::Create(BinOp->getOpcode(), NarrowOp0, X); - } - break; - } - - default: break; - } - - if (Instruction *NarrowOr = narrowRotate(Trunc)) - return NarrowOr; - - return nullptr; -} - -/// Try to narrow the width of a splat shuffle. This could be generalized to any -/// shuffle with a constant operand, but we limit the transform to avoid -/// creating a shuffle type that targets may not be able to lower effectively. -static Instruction *shrinkSplatShuffle(TruncInst &Trunc, - InstCombiner::BuilderTy &Builder) { - auto *Shuf = dyn_cast<ShuffleVectorInst>(Trunc.getOperand(0)); - if (Shuf && Shuf->hasOneUse() && isa<UndefValue>(Shuf->getOperand(1)) && - Shuf->getMask()->getSplatValue() && - Shuf->getType() == Shuf->getOperand(0)->getType()) { - // trunc (shuf X, Undef, SplatMask) --> shuf (trunc X), Undef, SplatMask - Constant *NarrowUndef = UndefValue::get(Trunc.getType()); - Value *NarrowOp = Builder.CreateTrunc(Shuf->getOperand(0), Trunc.getType()); - return new ShuffleVectorInst(NarrowOp, NarrowUndef, Shuf->getMask()); - } - - return nullptr; -} - -/// Try to narrow the width of an insert element. This could be generalized for -/// any vector constant, but we limit the transform to insertion into undef to -/// avoid potential backend problems from unsupported insertion widths. This -/// could also be extended to handle the case of inserting a scalar constant -/// into a vector variable. -static Instruction *shrinkInsertElt(CastInst &Trunc, - InstCombiner::BuilderTy &Builder) { - Instruction::CastOps Opcode = Trunc.getOpcode(); - assert((Opcode == Instruction::Trunc || Opcode == Instruction::FPTrunc) && - "Unexpected instruction for shrinking"); - - auto *InsElt = dyn_cast<InsertElementInst>(Trunc.getOperand(0)); - if (!InsElt || !InsElt->hasOneUse()) - return nullptr; - - Type *DestTy = Trunc.getType(); - Type *DestScalarTy = DestTy->getScalarType(); - Value *VecOp = InsElt->getOperand(0); - Value *ScalarOp = InsElt->getOperand(1); - Value *Index = InsElt->getOperand(2); - - if (isa<UndefValue>(VecOp)) { - // trunc (inselt undef, X, Index) --> inselt undef, (trunc X), Index - // fptrunc (inselt undef, X, Index) --> inselt undef, (fptrunc X), Index - UndefValue *NarrowUndef = UndefValue::get(DestTy); - Value *NarrowOp = Builder.CreateCast(Opcode, ScalarOp, DestScalarTy); - return InsertElementInst::Create(NarrowUndef, NarrowOp, Index); - } - - return nullptr; -} - -Instruction *InstCombiner::visitTrunc(TruncInst &CI) { - if (Instruction *Result = commonCastTransforms(CI)) - return Result; - - Value *Src = CI.getOperand(0); - Type *DestTy = CI.getType(), *SrcTy = Src->getType(); - - // Attempt to truncate the entire input expression tree to the destination - // type. Only do this if the dest type is a simple type, don't convert the - // expression tree to something weird like i93 unless the source is also - // strange. - if ((DestTy->isVectorTy() || shouldChangeType(SrcTy, DestTy)) && - canEvaluateTruncated(Src, DestTy, *this, &CI)) { - - // If this cast is a truncate, evaluting in a different type always - // eliminates the cast, so it is always a win. - LLVM_DEBUG( - dbgs() << "ICE: EvaluateInDifferentType converting expression type" - " to avoid cast: " - << CI << '\n'); - Value *Res = EvaluateInDifferentType(Src, DestTy, false); - assert(Res->getType() == DestTy); - return replaceInstUsesWith(CI, Res); - } - - // Test if the trunc is the user of a select which is part of a - // minimum or maximum operation. If so, don't do any more simplification. - // Even simplifying demanded bits can break the canonical form of a - // min/max. - Value *LHS, *RHS; - if (SelectInst *SI = dyn_cast<SelectInst>(CI.getOperand(0))) - if (matchSelectPattern(SI, LHS, RHS).Flavor != SPF_UNKNOWN) - return nullptr; - - // See if we can simplify any instructions used by the input whose sole - // purpose is to compute bits we don't care about. - if (SimplifyDemandedInstructionBits(CI)) - return &CI; - - if (DestTy->getScalarSizeInBits() == 1) { - Value *Zero = Constant::getNullValue(Src->getType()); - if (DestTy->isIntegerTy()) { - // Canonicalize trunc x to i1 -> icmp ne (and x, 1), 0 (scalar only). - // TODO: We canonicalize to more instructions here because we are probably - // lacking equivalent analysis for trunc relative to icmp. There may also - // be codegen concerns. If those trunc limitations were removed, we could - // remove this transform. - Value *And = Builder.CreateAnd(Src, ConstantInt::get(SrcTy, 1)); - return new ICmpInst(ICmpInst::ICMP_NE, And, Zero); - } - - // For vectors, we do not canonicalize all truncs to icmp, so optimize - // patterns that would be covered within visitICmpInst. - Value *X; - const APInt *C; - if (match(Src, m_OneUse(m_LShr(m_Value(X), m_APInt(C))))) { - // trunc (lshr X, C) to i1 --> icmp ne (and X, C'), 0 - APInt MaskC = APInt(SrcTy->getScalarSizeInBits(), 1).shl(*C); - Value *And = Builder.CreateAnd(X, ConstantInt::get(SrcTy, MaskC)); - return new ICmpInst(ICmpInst::ICMP_NE, And, Zero); - } - if (match(Src, m_OneUse(m_c_Or(m_LShr(m_Value(X), m_APInt(C)), - m_Deferred(X))))) { - // trunc (or (lshr X, C), X) to i1 --> icmp ne (and X, C'), 0 - APInt MaskC = APInt(SrcTy->getScalarSizeInBits(), 1).shl(*C) | 1; - Value *And = Builder.CreateAnd(X, ConstantInt::get(SrcTy, MaskC)); - return new ICmpInst(ICmpInst::ICMP_NE, And, Zero); - } - } - - // FIXME: Maybe combine the next two transforms to handle the no cast case - // more efficiently. Support vector types. Cleanup code by using m_OneUse. - - // Transform trunc(lshr (zext A), Cst) to eliminate one type conversion. - Value *A = nullptr; ConstantInt *Cst = nullptr; - if (Src->hasOneUse() && - match(Src, m_LShr(m_ZExt(m_Value(A)), m_ConstantInt(Cst)))) { - // We have three types to worry about here, the type of A, the source of - // the truncate (MidSize), and the destination of the truncate. We know that - // ASize < MidSize and MidSize > ResultSize, but don't know the relation - // between ASize and ResultSize. - unsigned ASize = A->getType()->getPrimitiveSizeInBits(); - - // If the shift amount is larger than the size of A, then the result is - // known to be zero because all the input bits got shifted out. - if (Cst->getZExtValue() >= ASize) - return replaceInstUsesWith(CI, Constant::getNullValue(DestTy)); - - // Since we're doing an lshr and a zero extend, and know that the shift - // amount is smaller than ASize, it is always safe to do the shift in A's - // type, then zero extend or truncate to the result. - Value *Shift = Builder.CreateLShr(A, Cst->getZExtValue()); - Shift->takeName(Src); - return CastInst::CreateIntegerCast(Shift, DestTy, false); - } - - // FIXME: We should canonicalize to zext/trunc and remove this transform. - // Transform trunc(lshr (sext A), Cst) to ashr A, Cst to eliminate type - // conversion. - // It works because bits coming from sign extension have the same value as - // the sign bit of the original value; performing ashr instead of lshr - // generates bits of the same value as the sign bit. - if (Src->hasOneUse() && - match(Src, m_LShr(m_SExt(m_Value(A)), m_ConstantInt(Cst)))) { - Value *SExt = cast<Instruction>(Src)->getOperand(0); - const unsigned SExtSize = SExt->getType()->getPrimitiveSizeInBits(); - const unsigned ASize = A->getType()->getPrimitiveSizeInBits(); - const unsigned CISize = CI.getType()->getPrimitiveSizeInBits(); - const unsigned MaxAmt = SExtSize - std::max(CISize, ASize); - unsigned ShiftAmt = Cst->getZExtValue(); - - // This optimization can be only performed when zero bits generated by - // the original lshr aren't pulled into the value after truncation, so we - // can only shift by values no larger than the number of extension bits. - // FIXME: Instead of bailing when the shift is too large, use and to clear - // the extra bits. - if (ShiftAmt <= MaxAmt) { - if (CISize == ASize) - return BinaryOperator::CreateAShr(A, ConstantInt::get(CI.getType(), - std::min(ShiftAmt, ASize - 1))); - if (SExt->hasOneUse()) { - Value *Shift = Builder.CreateAShr(A, std::min(ShiftAmt, ASize - 1)); - Shift->takeName(Src); - return CastInst::CreateIntegerCast(Shift, CI.getType(), true); - } - } - } - - if (Instruction *I = narrowBinOp(CI)) - return I; - - if (Instruction *I = shrinkSplatShuffle(CI, Builder)) - return I; - - if (Instruction *I = shrinkInsertElt(CI, Builder)) - return I; - - if (Src->hasOneUse() && isa<IntegerType>(SrcTy) && - shouldChangeType(SrcTy, DestTy)) { - // Transform "trunc (shl X, cst)" -> "shl (trunc X), cst" so long as the - // dest type is native and cst < dest size. - if (match(Src, m_Shl(m_Value(A), m_ConstantInt(Cst))) && - !match(A, m_Shr(m_Value(), m_Constant()))) { - // Skip shifts of shift by constants. It undoes a combine in - // FoldShiftByConstant and is the extend in reg pattern. - const unsigned DestSize = DestTy->getScalarSizeInBits(); - if (Cst->getValue().ult(DestSize)) { - Value *NewTrunc = Builder.CreateTrunc(A, DestTy, A->getName() + ".tr"); - - return BinaryOperator::Create( - Instruction::Shl, NewTrunc, - ConstantInt::get(DestTy, Cst->getValue().trunc(DestSize))); - } - } - } - - if (Instruction *I = foldVecTruncToExtElt(CI, *this)) - return I; - - return nullptr; -} - -Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, ZExtInst &CI, - bool DoTransform) { - // If we are just checking for a icmp eq of a single bit and zext'ing it - // to an integer, then shift the bit to the appropriate place and then - // cast to integer to avoid the comparison. - const APInt *Op1CV; - if (match(ICI->getOperand(1), m_APInt(Op1CV))) { - - // zext (x <s 0) to i32 --> x>>u31 true if signbit set. - // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear. - if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV->isNullValue()) || - (ICI->getPredicate() == ICmpInst::ICMP_SGT && Op1CV->isAllOnesValue())) { - if (!DoTransform) return ICI; - - Value *In = ICI->getOperand(0); - Value *Sh = ConstantInt::get(In->getType(), - In->getType()->getScalarSizeInBits() - 1); - In = Builder.CreateLShr(In, Sh, In->getName() + ".lobit"); - if (In->getType() != CI.getType()) - In = Builder.CreateIntCast(In, CI.getType(), false /*ZExt*/); - - if (ICI->getPredicate() == ICmpInst::ICMP_SGT) { - Constant *One = ConstantInt::get(In->getType(), 1); - In = Builder.CreateXor(In, One, In->getName() + ".not"); - } - - return replaceInstUsesWith(CI, In); - } - - // zext (X == 0) to i32 --> X^1 iff X has only the low bit set. - // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set. - // zext (X == 1) to i32 --> X iff X has only the low bit set. - // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set. - // zext (X != 0) to i32 --> X iff X has only the low bit set. - // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set. - // zext (X != 1) to i32 --> X^1 iff X has only the low bit set. - // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set. - if ((Op1CV->isNullValue() || Op1CV->isPowerOf2()) && - // This only works for EQ and NE - ICI->isEquality()) { - // If Op1C some other power of two, convert: - KnownBits Known = computeKnownBits(ICI->getOperand(0), 0, &CI); - - APInt KnownZeroMask(~Known.Zero); - if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1? - if (!DoTransform) return ICI; - - bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE; - if (!Op1CV->isNullValue() && (*Op1CV != KnownZeroMask)) { - // (X&4) == 2 --> false - // (X&4) != 2 --> true - Constant *Res = ConstantInt::get(CI.getType(), isNE); - return replaceInstUsesWith(CI, Res); - } - - uint32_t ShAmt = KnownZeroMask.logBase2(); - Value *In = ICI->getOperand(0); - if (ShAmt) { - // Perform a logical shr by shiftamt. - // Insert the shift to put the result in the low bit. - In = Builder.CreateLShr(In, ConstantInt::get(In->getType(), ShAmt), - In->getName() + ".lobit"); - } - - if (!Op1CV->isNullValue() == isNE) { // Toggle the low bit. - Constant *One = ConstantInt::get(In->getType(), 1); - In = Builder.CreateXor(In, One); - } - - if (CI.getType() == In->getType()) - return replaceInstUsesWith(CI, In); - - Value *IntCast = Builder.CreateIntCast(In, CI.getType(), false); - return replaceInstUsesWith(CI, IntCast); - } - } - } - - // icmp ne A, B is equal to xor A, B when A and B only really have one bit. - // It is also profitable to transform icmp eq into not(xor(A, B)) because that - // may lead to additional simplifications. - if (ICI->isEquality() && CI.getType() == ICI->getOperand(0)->getType()) { - if (IntegerType *ITy = dyn_cast<IntegerType>(CI.getType())) { - Value *LHS = ICI->getOperand(0); - Value *RHS = ICI->getOperand(1); - - KnownBits KnownLHS = computeKnownBits(LHS, 0, &CI); - KnownBits KnownRHS = computeKnownBits(RHS, 0, &CI); - - if (KnownLHS.Zero == KnownRHS.Zero && KnownLHS.One == KnownRHS.One) { - APInt KnownBits = KnownLHS.Zero | KnownLHS.One; - APInt UnknownBit = ~KnownBits; - if (UnknownBit.countPopulation() == 1) { - if (!DoTransform) return ICI; - - Value *Result = Builder.CreateXor(LHS, RHS); - - // Mask off any bits that are set and won't be shifted away. - if (KnownLHS.One.uge(UnknownBit)) - Result = Builder.CreateAnd(Result, - ConstantInt::get(ITy, UnknownBit)); - - // Shift the bit we're testing down to the lsb. - Result = Builder.CreateLShr( - Result, ConstantInt::get(ITy, UnknownBit.countTrailingZeros())); - - if (ICI->getPredicate() == ICmpInst::ICMP_EQ) - Result = Builder.CreateXor(Result, ConstantInt::get(ITy, 1)); - Result->takeName(ICI); - return replaceInstUsesWith(CI, Result); - } - } - } - } - - return nullptr; -} - -/// Determine if the specified value can be computed in the specified wider type -/// and produce the same low bits. If not, return false. -/// -/// If this function returns true, it can also return a non-zero number of bits -/// (in BitsToClear) which indicates that the value it computes is correct for -/// the zero extend, but that the additional BitsToClear bits need to be zero'd -/// out. For example, to promote something like: -/// -/// %B = trunc i64 %A to i32 -/// %C = lshr i32 %B, 8 -/// %E = zext i32 %C to i64 -/// -/// CanEvaluateZExtd for the 'lshr' will return true, and BitsToClear will be -/// set to 8 to indicate that the promoted value needs to have bits 24-31 -/// cleared in addition to bits 32-63. Since an 'and' will be generated to -/// clear the top bits anyway, doing this has no extra cost. -/// -/// This function works on both vectors and scalars. -static bool canEvaluateZExtd(Value *V, Type *Ty, unsigned &BitsToClear, - InstCombiner &IC, Instruction *CxtI) { - BitsToClear = 0; - if (canAlwaysEvaluateInType(V, Ty)) - return true; - if (canNotEvaluateInType(V, Ty)) - return false; - - auto *I = cast<Instruction>(V); - unsigned Tmp; - switch (I->getOpcode()) { - case Instruction::ZExt: // zext(zext(x)) -> zext(x). - case Instruction::SExt: // zext(sext(x)) -> sext(x). - case Instruction::Trunc: // zext(trunc(x)) -> trunc(x) or zext(x) - return true; - case Instruction::And: - case Instruction::Or: - case Instruction::Xor: - case Instruction::Add: - case Instruction::Sub: - case Instruction::Mul: - if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI) || - !canEvaluateZExtd(I->getOperand(1), Ty, Tmp, IC, CxtI)) - return false; - // These can all be promoted if neither operand has 'bits to clear'. - if (BitsToClear == 0 && Tmp == 0) - return true; - - // If the operation is an AND/OR/XOR and the bits to clear are zero in the - // other side, BitsToClear is ok. - if (Tmp == 0 && I->isBitwiseLogicOp()) { - // We use MaskedValueIsZero here for generality, but the case we care - // about the most is constant RHS. - unsigned VSize = V->getType()->getScalarSizeInBits(); - if (IC.MaskedValueIsZero(I->getOperand(1), - APInt::getHighBitsSet(VSize, BitsToClear), - 0, CxtI)) { - // If this is an And instruction and all of the BitsToClear are - // known to be zero we can reset BitsToClear. - if (I->getOpcode() == Instruction::And) - BitsToClear = 0; - return true; - } - } - - // Otherwise, we don't know how to analyze this BitsToClear case yet. - return false; - - case Instruction::Shl: { - // We can promote shl(x, cst) if we can promote x. Since shl overwrites the - // upper bits we can reduce BitsToClear by the shift amount. - const APInt *Amt; - if (match(I->getOperand(1), m_APInt(Amt))) { - if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI)) - return false; - uint64_t ShiftAmt = Amt->getZExtValue(); - BitsToClear = ShiftAmt < BitsToClear ? BitsToClear - ShiftAmt : 0; - return true; - } - return false; - } - case Instruction::LShr: { - // We can promote lshr(x, cst) if we can promote x. This requires the - // ultimate 'and' to clear out the high zero bits we're clearing out though. - const APInt *Amt; - if (match(I->getOperand(1), m_APInt(Amt))) { - if (!canEvaluateZExtd(I->getOperand(0), Ty, BitsToClear, IC, CxtI)) - return false; - BitsToClear += Amt->getZExtValue(); - if (BitsToClear > V->getType()->getScalarSizeInBits()) - BitsToClear = V->getType()->getScalarSizeInBits(); - return true; - } - // Cannot promote variable LSHR. - return false; - } - case Instruction::Select: - if (!canEvaluateZExtd(I->getOperand(1), Ty, Tmp, IC, CxtI) || - !canEvaluateZExtd(I->getOperand(2), Ty, BitsToClear, IC, CxtI) || - // TODO: If important, we could handle the case when the BitsToClear are - // known zero in the disagreeing side. - Tmp != BitsToClear) - return false; - return true; - - case Instruction::PHI: { - // We can change a phi if we can change all operands. Note that we never - // get into trouble with cyclic PHIs here because we only consider - // instructions with a single use. - PHINode *PN = cast<PHINode>(I); - if (!canEvaluateZExtd(PN->getIncomingValue(0), Ty, BitsToClear, IC, CxtI)) - return false; - for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) - if (!canEvaluateZExtd(PN->getIncomingValue(i), Ty, Tmp, IC, CxtI) || - // TODO: If important, we could handle the case when the BitsToClear - // are known zero in the disagreeing input. - Tmp != BitsToClear) - return false; - return true; - } - default: - // TODO: Can handle more cases here. - return false; - } -} - -Instruction *InstCombiner::visitZExt(ZExtInst &CI) { - // If this zero extend is only used by a truncate, let the truncate be - // eliminated before we try to optimize this zext. - if (CI.hasOneUse() && isa<TruncInst>(CI.user_back())) - return nullptr; - - // If one of the common conversion will work, do it. - if (Instruction *Result = commonCastTransforms(CI)) - return Result; - - Value *Src = CI.getOperand(0); - Type *SrcTy = Src->getType(), *DestTy = CI.getType(); - - // Try to extend the entire expression tree to the wide destination type. - unsigned BitsToClear; - if (shouldChangeType(SrcTy, DestTy) && - canEvaluateZExtd(Src, DestTy, BitsToClear, *this, &CI)) { - assert(BitsToClear <= SrcTy->getScalarSizeInBits() && - "Can't clear more bits than in SrcTy"); - - // Okay, we can transform this! Insert the new expression now. - LLVM_DEBUG( - dbgs() << "ICE: EvaluateInDifferentType converting expression type" - " to avoid zero extend: " - << CI << '\n'); - Value *Res = EvaluateInDifferentType(Src, DestTy, false); - assert(Res->getType() == DestTy); - - // Preserve debug values referring to Src if the zext is its last use. - if (auto *SrcOp = dyn_cast<Instruction>(Src)) - if (SrcOp->hasOneUse()) - replaceAllDbgUsesWith(*SrcOp, *Res, CI, DT); - - uint32_t SrcBitsKept = SrcTy->getScalarSizeInBits()-BitsToClear; - uint32_t DestBitSize = DestTy->getScalarSizeInBits(); - - // If the high bits are already filled with zeros, just replace this - // cast with the result. - if (MaskedValueIsZero(Res, - APInt::getHighBitsSet(DestBitSize, - DestBitSize-SrcBitsKept), - 0, &CI)) - return replaceInstUsesWith(CI, Res); - - // We need to emit an AND to clear the high bits. - Constant *C = ConstantInt::get(Res->getType(), - APInt::getLowBitsSet(DestBitSize, SrcBitsKept)); - return BinaryOperator::CreateAnd(Res, C); - } - - // If this is a TRUNC followed by a ZEXT then we are dealing with integral - // types and if the sizes are just right we can convert this into a logical - // 'and' which will be much cheaper than the pair of casts. - if (TruncInst *CSrc = dyn_cast<TruncInst>(Src)) { // A->B->C cast - // TODO: Subsume this into EvaluateInDifferentType. - - // Get the sizes of the types involved. We know that the intermediate type - // will be smaller than A or C, but don't know the relation between A and C. - Value *A = CSrc->getOperand(0); - unsigned SrcSize = A->getType()->getScalarSizeInBits(); - unsigned MidSize = CSrc->getType()->getScalarSizeInBits(); - unsigned DstSize = CI.getType()->getScalarSizeInBits(); - // If we're actually extending zero bits, then if - // SrcSize < DstSize: zext(a & mask) - // SrcSize == DstSize: a & mask - // SrcSize > DstSize: trunc(a) & mask - if (SrcSize < DstSize) { - APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize)); - Constant *AndConst = ConstantInt::get(A->getType(), AndValue); - Value *And = Builder.CreateAnd(A, AndConst, CSrc->getName() + ".mask"); - return new ZExtInst(And, CI.getType()); - } - - if (SrcSize == DstSize) { - APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize)); - return BinaryOperator::CreateAnd(A, ConstantInt::get(A->getType(), - AndValue)); - } - if (SrcSize > DstSize) { - Value *Trunc = Builder.CreateTrunc(A, CI.getType()); - APInt AndValue(APInt::getLowBitsSet(DstSize, MidSize)); - return BinaryOperator::CreateAnd(Trunc, - ConstantInt::get(Trunc->getType(), - AndValue)); - } - } - - if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src)) - return transformZExtICmp(ICI, CI); - - BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src); - if (SrcI && SrcI->getOpcode() == Instruction::Or) { - // zext (or icmp, icmp) -> or (zext icmp), (zext icmp) if at least one - // of the (zext icmp) can be eliminated. If so, immediately perform the - // according elimination. - ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0)); - ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1)); - if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() && - (transformZExtICmp(LHS, CI, false) || - transformZExtICmp(RHS, CI, false))) { - // zext (or icmp, icmp) -> or (zext icmp), (zext icmp) - Value *LCast = Builder.CreateZExt(LHS, CI.getType(), LHS->getName()); - Value *RCast = Builder.CreateZExt(RHS, CI.getType(), RHS->getName()); - BinaryOperator *Or = BinaryOperator::Create(Instruction::Or, LCast, RCast); - - // Perform the elimination. - if (auto *LZExt = dyn_cast<ZExtInst>(LCast)) - transformZExtICmp(LHS, *LZExt); - if (auto *RZExt = dyn_cast<ZExtInst>(RCast)) - transformZExtICmp(RHS, *RZExt); - - return Or; - } - } - - // zext(trunc(X) & C) -> (X & zext(C)). - Constant *C; - Value *X; - if (SrcI && - match(SrcI, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Constant(C)))) && - X->getType() == CI.getType()) - return BinaryOperator::CreateAnd(X, ConstantExpr::getZExt(C, CI.getType())); - - // zext((trunc(X) & C) ^ C) -> ((X & zext(C)) ^ zext(C)). - Value *And; - if (SrcI && match(SrcI, m_OneUse(m_Xor(m_Value(And), m_Constant(C)))) && - match(And, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Specific(C)))) && - X->getType() == CI.getType()) { - Constant *ZC = ConstantExpr::getZExt(C, CI.getType()); - return BinaryOperator::CreateXor(Builder.CreateAnd(X, ZC), ZC); - } - - return nullptr; -} - -/// Transform (sext icmp) to bitwise / integer operations to eliminate the icmp. -Instruction *InstCombiner::transformSExtICmp(ICmpInst *ICI, Instruction &CI) { - Value *Op0 = ICI->getOperand(0), *Op1 = ICI->getOperand(1); - ICmpInst::Predicate Pred = ICI->getPredicate(); - - // Don't bother if Op1 isn't of vector or integer type. - if (!Op1->getType()->isIntOrIntVectorTy()) - return nullptr; - - if ((Pred == ICmpInst::ICMP_SLT && match(Op1, m_ZeroInt())) || - (Pred == ICmpInst::ICMP_SGT && match(Op1, m_AllOnes()))) { - // (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if negative - // (x >s -1) ? -1 : 0 -> not (ashr x, 31) -> all ones if positive - Value *Sh = ConstantInt::get(Op0->getType(), - Op0->getType()->getScalarSizeInBits() - 1); - Value *In = Builder.CreateAShr(Op0, Sh, Op0->getName() + ".lobit"); - if (In->getType() != CI.getType()) - In = Builder.CreateIntCast(In, CI.getType(), true /*SExt*/); - - if (Pred == ICmpInst::ICMP_SGT) - In = Builder.CreateNot(In, In->getName() + ".not"); - return replaceInstUsesWith(CI, In); - } - - if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) { - // If we know that only one bit of the LHS of the icmp can be set and we - // have an equality comparison with zero or a power of 2, we can transform - // the icmp and sext into bitwise/integer operations. - if (ICI->hasOneUse() && - ICI->isEquality() && (Op1C->isZero() || Op1C->getValue().isPowerOf2())){ - KnownBits Known = computeKnownBits(Op0, 0, &CI); - - APInt KnownZeroMask(~Known.Zero); - if (KnownZeroMask.isPowerOf2()) { - Value *In = ICI->getOperand(0); - - // If the icmp tests for a known zero bit we can constant fold it. - if (!Op1C->isZero() && Op1C->getValue() != KnownZeroMask) { - Value *V = Pred == ICmpInst::ICMP_NE ? - ConstantInt::getAllOnesValue(CI.getType()) : - ConstantInt::getNullValue(CI.getType()); - return replaceInstUsesWith(CI, V); - } - - if (!Op1C->isZero() == (Pred == ICmpInst::ICMP_NE)) { - // sext ((x & 2^n) == 0) -> (x >> n) - 1 - // sext ((x & 2^n) != 2^n) -> (x >> n) - 1 - unsigned ShiftAmt = KnownZeroMask.countTrailingZeros(); - // Perform a right shift to place the desired bit in the LSB. - if (ShiftAmt) - In = Builder.CreateLShr(In, - ConstantInt::get(In->getType(), ShiftAmt)); - - // At this point "In" is either 1 or 0. Subtract 1 to turn - // {1, 0} -> {0, -1}. - In = Builder.CreateAdd(In, - ConstantInt::getAllOnesValue(In->getType()), - "sext"); - } else { - // sext ((x & 2^n) != 0) -> (x << bitwidth-n) a>> bitwidth-1 - // sext ((x & 2^n) == 2^n) -> (x << bitwidth-n) a>> bitwidth-1 - unsigned ShiftAmt = KnownZeroMask.countLeadingZeros(); - // Perform a left shift to place the desired bit in the MSB. - if (ShiftAmt) - In = Builder.CreateShl(In, - ConstantInt::get(In->getType(), ShiftAmt)); - - // Distribute the bit over the whole bit width. - In = Builder.CreateAShr(In, ConstantInt::get(In->getType(), - KnownZeroMask.getBitWidth() - 1), "sext"); - } - - if (CI.getType() == In->getType()) - return replaceInstUsesWith(CI, In); - return CastInst::CreateIntegerCast(In, CI.getType(), true/*SExt*/); - } - } - } - - return nullptr; -} - -/// Return true if we can take the specified value and return it as type Ty -/// without inserting any new casts and without changing the value of the common -/// low bits. This is used by code that tries to promote integer operations to -/// a wider types will allow us to eliminate the extension. -/// -/// This function works on both vectors and scalars. -/// -static bool canEvaluateSExtd(Value *V, Type *Ty) { - assert(V->getType()->getScalarSizeInBits() < Ty->getScalarSizeInBits() && - "Can't sign extend type to a smaller type"); - if (canAlwaysEvaluateInType(V, Ty)) - return true; - if (canNotEvaluateInType(V, Ty)) - return false; - - auto *I = cast<Instruction>(V); - switch (I->getOpcode()) { - case Instruction::SExt: // sext(sext(x)) -> sext(x) - case Instruction::ZExt: // sext(zext(x)) -> zext(x) - case Instruction::Trunc: // sext(trunc(x)) -> trunc(x) or sext(x) - return true; - case Instruction::And: - case Instruction::Or: - case Instruction::Xor: - case Instruction::Add: - case Instruction::Sub: - case Instruction::Mul: - // These operators can all arbitrarily be extended if their inputs can. - return canEvaluateSExtd(I->getOperand(0), Ty) && - canEvaluateSExtd(I->getOperand(1), Ty); - - //case Instruction::Shl: TODO - //case Instruction::LShr: TODO - - case Instruction::Select: - return canEvaluateSExtd(I->getOperand(1), Ty) && - canEvaluateSExtd(I->getOperand(2), Ty); - - case Instruction::PHI: { - // We can change a phi if we can change all operands. Note that we never - // get into trouble with cyclic PHIs here because we only consider - // instructions with a single use. - PHINode *PN = cast<PHINode>(I); - for (Value *IncValue : PN->incoming_values()) - if (!canEvaluateSExtd(IncValue, Ty)) return false; - return true; - } - default: - // TODO: Can handle more cases here. - break; - } - - return false; -} - -Instruction *InstCombiner::visitSExt(SExtInst &CI) { - // If this sign extend is only used by a truncate, let the truncate be - // eliminated before we try to optimize this sext. - if (CI.hasOneUse() && isa<TruncInst>(CI.user_back())) - return nullptr; - - if (Instruction *I = commonCastTransforms(CI)) - return I; - - Value *Src = CI.getOperand(0); - Type *SrcTy = Src->getType(), *DestTy = CI.getType(); - - // If we know that the value being extended is positive, we can use a zext - // instead. - KnownBits Known = computeKnownBits(Src, 0, &CI); - if (Known.isNonNegative()) - return CastInst::Create(Instruction::ZExt, Src, DestTy); - - // Try to extend the entire expression tree to the wide destination type. - if (shouldChangeType(SrcTy, DestTy) && canEvaluateSExtd(Src, DestTy)) { - // Okay, we can transform this! Insert the new expression now. - LLVM_DEBUG( - dbgs() << "ICE: EvaluateInDifferentType converting expression type" - " to avoid sign extend: " - << CI << '\n'); - Value *Res = EvaluateInDifferentType(Src, DestTy, true); - assert(Res->getType() == DestTy); - - uint32_t SrcBitSize = SrcTy->getScalarSizeInBits(); - uint32_t DestBitSize = DestTy->getScalarSizeInBits(); - - // If the high bits are already filled with sign bit, just replace this - // cast with the result. - if (ComputeNumSignBits(Res, 0, &CI) > DestBitSize - SrcBitSize) - return replaceInstUsesWith(CI, Res); - - // We need to emit a shl + ashr to do the sign extend. - Value *ShAmt = ConstantInt::get(DestTy, DestBitSize-SrcBitSize); - return BinaryOperator::CreateAShr(Builder.CreateShl(Res, ShAmt, "sext"), - ShAmt); - } - - // If the input is a trunc from the destination type, then turn sext(trunc(x)) - // into shifts. - Value *X; - if (match(Src, m_OneUse(m_Trunc(m_Value(X)))) && X->getType() == DestTy) { - // sext(trunc(X)) --> ashr(shl(X, C), C) - unsigned SrcBitSize = SrcTy->getScalarSizeInBits(); - unsigned DestBitSize = DestTy->getScalarSizeInBits(); - Constant *ShAmt = ConstantInt::get(DestTy, DestBitSize - SrcBitSize); - return BinaryOperator::CreateAShr(Builder.CreateShl(X, ShAmt), ShAmt); - } - - if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src)) - return transformSExtICmp(ICI, CI); - - // If the input is a shl/ashr pair of a same constant, then this is a sign - // extension from a smaller value. If we could trust arbitrary bitwidth - // integers, we could turn this into a truncate to the smaller bit and then - // use a sext for the whole extension. Since we don't, look deeper and check - // for a truncate. If the source and dest are the same type, eliminate the - // trunc and extend and just do shifts. For example, turn: - // %a = trunc i32 %i to i8 - // %b = shl i8 %a, 6 - // %c = ashr i8 %b, 6 - // %d = sext i8 %c to i32 - // into: - // %a = shl i32 %i, 30 - // %d = ashr i32 %a, 30 - Value *A = nullptr; - // TODO: Eventually this could be subsumed by EvaluateInDifferentType. - ConstantInt *BA = nullptr, *CA = nullptr; - if (match(Src, m_AShr(m_Shl(m_Trunc(m_Value(A)), m_ConstantInt(BA)), - m_ConstantInt(CA))) && - BA == CA && A->getType() == CI.getType()) { - unsigned MidSize = Src->getType()->getScalarSizeInBits(); - unsigned SrcDstSize = CI.getType()->getScalarSizeInBits(); - unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize; - Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt); - A = Builder.CreateShl(A, ShAmtV, CI.getName()); - return BinaryOperator::CreateAShr(A, ShAmtV); - } - - return nullptr; -} - - -/// Return a Constant* for the specified floating-point constant if it fits -/// in the specified FP type without changing its value. -static bool fitsInFPType(ConstantFP *CFP, const fltSemantics &Sem) { - bool losesInfo; - APFloat F = CFP->getValueAPF(); - (void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo); - return !losesInfo; -} - -static Type *shrinkFPConstant(ConstantFP *CFP) { - if (CFP->getType() == Type::getPPC_FP128Ty(CFP->getContext())) - return nullptr; // No constant folding of this. - // See if the value can be truncated to half and then reextended. - if (fitsInFPType(CFP, APFloat::IEEEhalf())) - return Type::getHalfTy(CFP->getContext()); - // See if the value can be truncated to float and then reextended. - if (fitsInFPType(CFP, APFloat::IEEEsingle())) - return Type::getFloatTy(CFP->getContext()); - if (CFP->getType()->isDoubleTy()) - return nullptr; // Won't shrink. - if (fitsInFPType(CFP, APFloat::IEEEdouble())) - return Type::getDoubleTy(CFP->getContext()); - // Don't try to shrink to various long double types. - return nullptr; -} - -// Determine if this is a vector of ConstantFPs and if so, return the minimal -// type we can safely truncate all elements to. -// TODO: Make these support undef elements. -static Type *shrinkFPConstantVector(Value *V) { - auto *CV = dyn_cast<Constant>(V); - if (!CV || !CV->getType()->isVectorTy()) - return nullptr; - - Type *MinType = nullptr; - - unsigned NumElts = CV->getType()->getVectorNumElements(); - for (unsigned i = 0; i != NumElts; ++i) { - auto *CFP = dyn_cast_or_null<ConstantFP>(CV->getAggregateElement(i)); - if (!CFP) - return nullptr; - - Type *T = shrinkFPConstant(CFP); - if (!T) - return nullptr; - - // If we haven't found a type yet or this type has a larger mantissa than - // our previous type, this is our new minimal type. - if (!MinType || T->getFPMantissaWidth() > MinType->getFPMantissaWidth()) - MinType = T; - } - - // Make a vector type from the minimal type. - return VectorType::get(MinType, NumElts); -} - -/// Find the minimum FP type we can safely truncate to. -static Type *getMinimumFPType(Value *V) { - if (auto *FPExt = dyn_cast<FPExtInst>(V)) - return FPExt->getOperand(0)->getType(); - - // If this value is a constant, return the constant in the smallest FP type - // that can accurately represent it. This allows us to turn - // (float)((double)X+2.0) into x+2.0f. - if (auto *CFP = dyn_cast<ConstantFP>(V)) - if (Type *T = shrinkFPConstant(CFP)) - return T; - - // Try to shrink a vector of FP constants. - if (Type *T = shrinkFPConstantVector(V)) - return T; - - return V->getType(); -} - -Instruction *InstCombiner::visitFPTrunc(FPTruncInst &FPT) { - if (Instruction *I = commonCastTransforms(FPT)) - return I; - - // If we have fptrunc(OpI (fpextend x), (fpextend y)), we would like to - // simplify this expression to avoid one or more of the trunc/extend - // operations if we can do so without changing the numerical results. - // - // The exact manner in which the widths of the operands interact to limit - // what we can and cannot do safely varies from operation to operation, and - // is explained below in the various case statements. - Type *Ty = FPT.getType(); - BinaryOperator *OpI = dyn_cast<BinaryOperator>(FPT.getOperand(0)); - if (OpI && OpI->hasOneUse()) { - Type *LHSMinType = getMinimumFPType(OpI->getOperand(0)); - Type *RHSMinType = getMinimumFPType(OpI->getOperand(1)); - unsigned OpWidth = OpI->getType()->getFPMantissaWidth(); - unsigned LHSWidth = LHSMinType->getFPMantissaWidth(); - unsigned RHSWidth = RHSMinType->getFPMantissaWidth(); - unsigned SrcWidth = std::max(LHSWidth, RHSWidth); - unsigned DstWidth = Ty->getFPMantissaWidth(); - switch (OpI->getOpcode()) { - default: break; - case Instruction::FAdd: - case Instruction::FSub: - // For addition and subtraction, the infinitely precise result can - // essentially be arbitrarily wide; proving that double rounding - // will not occur because the result of OpI is exact (as we will for - // FMul, for example) is hopeless. However, we *can* nonetheless - // frequently know that double rounding cannot occur (or that it is - // innocuous) by taking advantage of the specific structure of - // infinitely-precise results that admit double rounding. - // - // Specifically, if OpWidth >= 2*DstWdith+1 and DstWidth is sufficient - // to represent both sources, we can guarantee that the double - // rounding is innocuous (See p50 of Figueroa's 2000 PhD thesis, - // "A Rigorous Framework for Fully Supporting the IEEE Standard ..." - // for proof of this fact). - // - // Note: Figueroa does not consider the case where DstFormat != - // SrcFormat. It's possible (likely even!) that this analysis - // could be tightened for those cases, but they are rare (the main - // case of interest here is (float)((double)float + float)). - if (OpWidth >= 2*DstWidth+1 && DstWidth >= SrcWidth) { - Value *LHS = Builder.CreateFPTrunc(OpI->getOperand(0), Ty); - Value *RHS = Builder.CreateFPTrunc(OpI->getOperand(1), Ty); - Instruction *RI = BinaryOperator::Create(OpI->getOpcode(), LHS, RHS); - RI->copyFastMathFlags(OpI); - return RI; - } - break; - case Instruction::FMul: - // For multiplication, the infinitely precise result has at most - // LHSWidth + RHSWidth significant bits; if OpWidth is sufficient - // that such a value can be exactly represented, then no double - // rounding can possibly occur; we can safely perform the operation - // in the destination format if it can represent both sources. - if (OpWidth >= LHSWidth + RHSWidth && DstWidth >= SrcWidth) { - Value *LHS = Builder.CreateFPTrunc(OpI->getOperand(0), Ty); - Value *RHS = Builder.CreateFPTrunc(OpI->getOperand(1), Ty); - return BinaryOperator::CreateFMulFMF(LHS, RHS, OpI); - } - break; - case Instruction::FDiv: - // For division, we use again use the bound from Figueroa's - // dissertation. I am entirely certain that this bound can be - // tightened in the unbalanced operand case by an analysis based on - // the diophantine rational approximation bound, but the well-known - // condition used here is a good conservative first pass. - // TODO: Tighten bound via rigorous analysis of the unbalanced case. - if (OpWidth >= 2*DstWidth && DstWidth >= SrcWidth) { - Value *LHS = Builder.CreateFPTrunc(OpI->getOperand(0), Ty); - Value *RHS = Builder.CreateFPTrunc(OpI->getOperand(1), Ty); - return BinaryOperator::CreateFDivFMF(LHS, RHS, OpI); - } - break; - case Instruction::FRem: { - // Remainder is straightforward. Remainder is always exact, so the - // type of OpI doesn't enter into things at all. We simply evaluate - // in whichever source type is larger, then convert to the - // destination type. - if (SrcWidth == OpWidth) - break; - Value *LHS, *RHS; - if (LHSWidth == SrcWidth) { - LHS = Builder.CreateFPTrunc(OpI->getOperand(0), LHSMinType); - RHS = Builder.CreateFPTrunc(OpI->getOperand(1), LHSMinType); - } else { - LHS = Builder.CreateFPTrunc(OpI->getOperand(0), RHSMinType); - RHS = Builder.CreateFPTrunc(OpI->getOperand(1), RHSMinType); - } - - Value *ExactResult = Builder.CreateFRemFMF(LHS, RHS, OpI); - return CastInst::CreateFPCast(ExactResult, Ty); - } - } - } - - // (fptrunc (fneg x)) -> (fneg (fptrunc x)) - Value *X; - Instruction *Op = dyn_cast<Instruction>(FPT.getOperand(0)); - if (Op && Op->hasOneUse()) { - if (match(Op, m_FNeg(m_Value(X)))) { - Value *InnerTrunc = Builder.CreateFPTrunc(X, Ty); - - // FIXME: Once we're sure that unary FNeg optimizations are on par with - // binary FNeg, this should always return a unary operator. - if (isa<BinaryOperator>(Op)) - return BinaryOperator::CreateFNegFMF(InnerTrunc, Op); - return UnaryOperator::CreateFNegFMF(InnerTrunc, Op); - } - } - - if (auto *II = dyn_cast<IntrinsicInst>(FPT.getOperand(0))) { - switch (II->getIntrinsicID()) { - default: break; - case Intrinsic::ceil: - case Intrinsic::fabs: - case Intrinsic::floor: - case Intrinsic::nearbyint: - case Intrinsic::rint: - case Intrinsic::round: - case Intrinsic::trunc: { - Value *Src = II->getArgOperand(0); - if (!Src->hasOneUse()) - break; - - // Except for fabs, this transformation requires the input of the unary FP - // operation to be itself an fpext from the type to which we're - // truncating. - if (II->getIntrinsicID() != Intrinsic::fabs) { - FPExtInst *FPExtSrc = dyn_cast<FPExtInst>(Src); - if (!FPExtSrc || FPExtSrc->getSrcTy() != Ty) - break; - } - - // Do unary FP operation on smaller type. - // (fptrunc (fabs x)) -> (fabs (fptrunc x)) - Value *InnerTrunc = Builder.CreateFPTrunc(Src, Ty); - Function *Overload = Intrinsic::getDeclaration(FPT.getModule(), - II->getIntrinsicID(), Ty); - SmallVector<OperandBundleDef, 1> OpBundles; - II->getOperandBundlesAsDefs(OpBundles); - CallInst *NewCI = - CallInst::Create(Overload, {InnerTrunc}, OpBundles, II->getName()); - NewCI->copyFastMathFlags(II); - return NewCI; - } - } - } - - if (Instruction *I = shrinkInsertElt(FPT, Builder)) - return I; - - return nullptr; -} - -Instruction *InstCombiner::visitFPExt(CastInst &CI) { - return commonCastTransforms(CI); -} - -// fpto{s/u}i({u/s}itofp(X)) --> X or zext(X) or sext(X) or trunc(X) -// This is safe if the intermediate type has enough bits in its mantissa to -// accurately represent all values of X. For example, this won't work with -// i64 -> float -> i64. -Instruction *InstCombiner::FoldItoFPtoI(Instruction &FI) { - if (!isa<UIToFPInst>(FI.getOperand(0)) && !isa<SIToFPInst>(FI.getOperand(0))) - return nullptr; - Instruction *OpI = cast<Instruction>(FI.getOperand(0)); - - Value *SrcI = OpI->getOperand(0); - Type *FITy = FI.getType(); - Type *OpITy = OpI->getType(); - Type *SrcTy = SrcI->getType(); - bool IsInputSigned = isa<SIToFPInst>(OpI); - bool IsOutputSigned = isa<FPToSIInst>(FI); - - // We can safely assume the conversion won't overflow the output range, - // because (for example) (uint8_t)18293.f is undefined behavior. - - // Since we can assume the conversion won't overflow, our decision as to - // whether the input will fit in the float should depend on the minimum - // of the input range and output range. - - // This means this is also safe for a signed input and unsigned output, since - // a negative input would lead to undefined behavior. - int InputSize = (int)SrcTy->getScalarSizeInBits() - IsInputSigned; - int OutputSize = (int)FITy->getScalarSizeInBits() - IsOutputSigned; - int ActualSize = std::min(InputSize, OutputSize); - - if (ActualSize <= OpITy->getFPMantissaWidth()) { - if (FITy->getScalarSizeInBits() > SrcTy->getScalarSizeInBits()) { - if (IsInputSigned && IsOutputSigned) - return new SExtInst(SrcI, FITy); - return new ZExtInst(SrcI, FITy); - } - if (FITy->getScalarSizeInBits() < SrcTy->getScalarSizeInBits()) - return new TruncInst(SrcI, FITy); - if (SrcTy == FITy) - return replaceInstUsesWith(FI, SrcI); - return new BitCastInst(SrcI, FITy); - } - return nullptr; -} - -Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) { - Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0)); - if (!OpI) - return commonCastTransforms(FI); - - if (Instruction *I = FoldItoFPtoI(FI)) - return I; - - return commonCastTransforms(FI); -} - -Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) { - Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0)); - if (!OpI) - return commonCastTransforms(FI); - - if (Instruction *I = FoldItoFPtoI(FI)) - return I; - - return commonCastTransforms(FI); -} - -Instruction *InstCombiner::visitUIToFP(CastInst &CI) { - return commonCastTransforms(CI); -} - -Instruction *InstCombiner::visitSIToFP(CastInst &CI) { - return commonCastTransforms(CI); -} - -Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) { - // If the source integer type is not the intptr_t type for this target, do a - // trunc or zext to the intptr_t type, then inttoptr of it. This allows the - // cast to be exposed to other transforms. - unsigned AS = CI.getAddressSpace(); - if (CI.getOperand(0)->getType()->getScalarSizeInBits() != - DL.getPointerSizeInBits(AS)) { - Type *Ty = DL.getIntPtrType(CI.getContext(), AS); - if (CI.getType()->isVectorTy()) // Handle vectors of pointers. - Ty = VectorType::get(Ty, CI.getType()->getVectorNumElements()); - - Value *P = Builder.CreateZExtOrTrunc(CI.getOperand(0), Ty); - return new IntToPtrInst(P, CI.getType()); - } - - if (Instruction *I = commonCastTransforms(CI)) - return I; - - return nullptr; -} - -/// Implement the transforms for cast of pointer (bitcast/ptrtoint) -Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) { - Value *Src = CI.getOperand(0); - - if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) { - // If casting the result of a getelementptr instruction with no offset, turn - // this into a cast of the original pointer! - if (GEP->hasAllZeroIndices() && - // If CI is an addrspacecast and GEP changes the poiner type, merging - // GEP into CI would undo canonicalizing addrspacecast with different - // pointer types, causing infinite loops. - (!isa<AddrSpaceCastInst>(CI) || - GEP->getType() == GEP->getPointerOperandType())) { - // Changing the cast operand is usually not a good idea but it is safe - // here because the pointer operand is being replaced with another - // pointer operand so the opcode doesn't need to change. - Worklist.Add(GEP); - CI.setOperand(0, GEP->getOperand(0)); - return &CI; - } - } - - return commonCastTransforms(CI); -} - -Instruction *InstCombiner::visitPtrToInt(PtrToIntInst &CI) { - // If the destination integer type is not the intptr_t type for this target, - // do a ptrtoint to intptr_t then do a trunc or zext. This allows the cast - // to be exposed to other transforms. - - Type *Ty = CI.getType(); - unsigned AS = CI.getPointerAddressSpace(); - - if (Ty->getScalarSizeInBits() == DL.getIndexSizeInBits(AS)) - return commonPointerCastTransforms(CI); - - Type *PtrTy = DL.getIntPtrType(CI.getContext(), AS); - if (Ty->isVectorTy()) // Handle vectors of pointers. - PtrTy = VectorType::get(PtrTy, Ty->getVectorNumElements()); - - Value *P = Builder.CreatePtrToInt(CI.getOperand(0), PtrTy); - return CastInst::CreateIntegerCast(P, Ty, /*isSigned=*/false); -} - -/// This input value (which is known to have vector type) is being zero extended -/// or truncated to the specified vector type. -/// Try to replace it with a shuffle (and vector/vector bitcast) if possible. -/// -/// The source and destination vector types may have different element types. -static Instruction *optimizeVectorResize(Value *InVal, VectorType *DestTy, - InstCombiner &IC) { - // We can only do this optimization if the output is a multiple of the input - // element size, or the input is a multiple of the output element size. - // Convert the input type to have the same element type as the output. - VectorType *SrcTy = cast<VectorType>(InVal->getType()); - - if (SrcTy->getElementType() != DestTy->getElementType()) { - // The input types don't need to be identical, but for now they must be the - // same size. There is no specific reason we couldn't handle things like - // <4 x i16> -> <4 x i32> by bitcasting to <2 x i32> but haven't gotten - // there yet. - if (SrcTy->getElementType()->getPrimitiveSizeInBits() != - DestTy->getElementType()->getPrimitiveSizeInBits()) - return nullptr; - - SrcTy = VectorType::get(DestTy->getElementType(), SrcTy->getNumElements()); - InVal = IC.Builder.CreateBitCast(InVal, SrcTy); - } - - // Now that the element types match, get the shuffle mask and RHS of the - // shuffle to use, which depends on whether we're increasing or decreasing the - // size of the input. - SmallVector<uint32_t, 16> ShuffleMask; - Value *V2; - - if (SrcTy->getNumElements() > DestTy->getNumElements()) { - // If we're shrinking the number of elements, just shuffle in the low - // elements from the input and use undef as the second shuffle input. - V2 = UndefValue::get(SrcTy); - for (unsigned i = 0, e = DestTy->getNumElements(); i != e; ++i) - ShuffleMask.push_back(i); - - } else { - // If we're increasing the number of elements, shuffle in all of the - // elements from InVal and fill the rest of the result elements with zeros - // from a constant zero. - V2 = Constant::getNullValue(SrcTy); - unsigned SrcElts = SrcTy->getNumElements(); - for (unsigned i = 0, e = SrcElts; i != e; ++i) - ShuffleMask.push_back(i); - - // The excess elements reference the first element of the zero input. - for (unsigned i = 0, e = DestTy->getNumElements()-SrcElts; i != e; ++i) - ShuffleMask.push_back(SrcElts); - } - - return new ShuffleVectorInst(InVal, V2, - ConstantDataVector::get(V2->getContext(), - ShuffleMask)); -} - -static bool isMultipleOfTypeSize(unsigned Value, Type *Ty) { - return Value % Ty->getPrimitiveSizeInBits() == 0; -} - -static unsigned getTypeSizeIndex(unsigned Value, Type *Ty) { - return Value / Ty->getPrimitiveSizeInBits(); -} - -/// V is a value which is inserted into a vector of VecEltTy. -/// Look through the value to see if we can decompose it into -/// insertions into the vector. See the example in the comment for -/// OptimizeIntegerToVectorInsertions for the pattern this handles. -/// The type of V is always a non-zero multiple of VecEltTy's size. -/// Shift is the number of bits between the lsb of V and the lsb of -/// the vector. -/// -/// This returns false if the pattern can't be matched or true if it can, -/// filling in Elements with the elements found here. -static bool collectInsertionElements(Value *V, unsigned Shift, - SmallVectorImpl<Value *> &Elements, - Type *VecEltTy, bool isBigEndian) { - assert(isMultipleOfTypeSize(Shift, VecEltTy) && - "Shift should be a multiple of the element type size"); - - // Undef values never contribute useful bits to the result. - if (isa<UndefValue>(V)) return true; - - // If we got down to a value of the right type, we win, try inserting into the - // right element. - if (V->getType() == VecEltTy) { - // Inserting null doesn't actually insert any elements. - if (Constant *C = dyn_cast<Constant>(V)) - if (C->isNullValue()) - return true; - - unsigned ElementIndex = getTypeSizeIndex(Shift, VecEltTy); - if (isBigEndian) - ElementIndex = Elements.size() - ElementIndex - 1; - - // Fail if multiple elements are inserted into this slot. - if (Elements[ElementIndex]) - return false; - - Elements[ElementIndex] = V; - return true; - } - - if (Constant *C = dyn_cast<Constant>(V)) { - // Figure out the # elements this provides, and bitcast it or slice it up - // as required. - unsigned NumElts = getTypeSizeIndex(C->getType()->getPrimitiveSizeInBits(), - VecEltTy); - // If the constant is the size of a vector element, we just need to bitcast - // it to the right type so it gets properly inserted. - if (NumElts == 1) - return collectInsertionElements(ConstantExpr::getBitCast(C, VecEltTy), - Shift, Elements, VecEltTy, isBigEndian); - - // Okay, this is a constant that covers multiple elements. Slice it up into - // pieces and insert each element-sized piece into the vector. - if (!isa<IntegerType>(C->getType())) - C = ConstantExpr::getBitCast(C, IntegerType::get(V->getContext(), - C->getType()->getPrimitiveSizeInBits())); - unsigned ElementSize = VecEltTy->getPrimitiveSizeInBits(); - Type *ElementIntTy = IntegerType::get(C->getContext(), ElementSize); - - for (unsigned i = 0; i != NumElts; ++i) { - unsigned ShiftI = Shift+i*ElementSize; - Constant *Piece = ConstantExpr::getLShr(C, ConstantInt::get(C->getType(), - ShiftI)); - Piece = ConstantExpr::getTrunc(Piece, ElementIntTy); - if (!collectInsertionElements(Piece, ShiftI, Elements, VecEltTy, - isBigEndian)) - return false; - } - return true; - } - - if (!V->hasOneUse()) return false; - - Instruction *I = dyn_cast<Instruction>(V); - if (!I) return false; - switch (I->getOpcode()) { - default: return false; // Unhandled case. - case Instruction::BitCast: - return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy, - isBigEndian); - case Instruction::ZExt: - if (!isMultipleOfTypeSize( - I->getOperand(0)->getType()->getPrimitiveSizeInBits(), - VecEltTy)) - return false; - return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy, - isBigEndian); - case Instruction::Or: - return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy, - isBigEndian) && - collectInsertionElements(I->getOperand(1), Shift, Elements, VecEltTy, - isBigEndian); - case Instruction::Shl: { - // Must be shifting by a constant that is a multiple of the element size. - ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1)); - if (!CI) return false; - Shift += CI->getZExtValue(); - if (!isMultipleOfTypeSize(Shift, VecEltTy)) return false; - return collectInsertionElements(I->getOperand(0), Shift, Elements, VecEltTy, - isBigEndian); - } - - } -} - - -/// If the input is an 'or' instruction, we may be doing shifts and ors to -/// assemble the elements of the vector manually. -/// Try to rip the code out and replace it with insertelements. This is to -/// optimize code like this: -/// -/// %tmp37 = bitcast float %inc to i32 -/// %tmp38 = zext i32 %tmp37 to i64 -/// %tmp31 = bitcast float %inc5 to i32 -/// %tmp32 = zext i32 %tmp31 to i64 -/// %tmp33 = shl i64 %tmp32, 32 -/// %ins35 = or i64 %tmp33, %tmp38 -/// %tmp43 = bitcast i64 %ins35 to <2 x float> -/// -/// Into two insertelements that do "buildvector{%inc, %inc5}". -static Value *optimizeIntegerToVectorInsertions(BitCastInst &CI, - InstCombiner &IC) { - VectorType *DestVecTy = cast<VectorType>(CI.getType()); - Value *IntInput = CI.getOperand(0); - - SmallVector<Value*, 8> Elements(DestVecTy->getNumElements()); - if (!collectInsertionElements(IntInput, 0, Elements, - DestVecTy->getElementType(), - IC.getDataLayout().isBigEndian())) - return nullptr; - - // If we succeeded, we know that all of the element are specified by Elements - // or are zero if Elements has a null entry. Recast this as a set of - // insertions. - Value *Result = Constant::getNullValue(CI.getType()); - for (unsigned i = 0, e = Elements.size(); i != e; ++i) { - if (!Elements[i]) continue; // Unset element. - - Result = IC.Builder.CreateInsertElement(Result, Elements[i], - IC.Builder.getInt32(i)); - } - - return Result; -} - -/// Canonicalize scalar bitcasts of extracted elements into a bitcast of the -/// vector followed by extract element. The backend tends to handle bitcasts of -/// vectors better than bitcasts of scalars because vector registers are -/// usually not type-specific like scalar integer or scalar floating-point. -static Instruction *canonicalizeBitCastExtElt(BitCastInst &BitCast, - InstCombiner &IC) { - // TODO: Create and use a pattern matcher for ExtractElementInst. - auto *ExtElt = dyn_cast<ExtractElementInst>(BitCast.getOperand(0)); - if (!ExtElt || !ExtElt->hasOneUse()) - return nullptr; - - // The bitcast must be to a vectorizable type, otherwise we can't make a new - // type to extract from. - Type *DestType = BitCast.getType(); - if (!VectorType::isValidElementType(DestType)) - return nullptr; - - unsigned NumElts = ExtElt->getVectorOperandType()->getNumElements(); - auto *NewVecType = VectorType::get(DestType, NumElts); - auto *NewBC = IC.Builder.CreateBitCast(ExtElt->getVectorOperand(), - NewVecType, "bc"); - return ExtractElementInst::Create(NewBC, ExtElt->getIndexOperand()); -} - -/// Change the type of a bitwise logic operation if we can eliminate a bitcast. -static Instruction *foldBitCastBitwiseLogic(BitCastInst &BitCast, - InstCombiner::BuilderTy &Builder) { - Type *DestTy = BitCast.getType(); - BinaryOperator *BO; - if (!DestTy->isIntOrIntVectorTy() || - !match(BitCast.getOperand(0), m_OneUse(m_BinOp(BO))) || - !BO->isBitwiseLogicOp()) - return nullptr; - - // FIXME: This transform is restricted to vector types to avoid backend - // problems caused by creating potentially illegal operations. If a fix-up is - // added to handle that situation, we can remove this check. - if (!DestTy->isVectorTy() || !BO->getType()->isVectorTy()) - return nullptr; - - Value *X; - if (match(BO->getOperand(0), m_OneUse(m_BitCast(m_Value(X)))) && - X->getType() == DestTy && !isa<Constant>(X)) { - // bitcast(logic(bitcast(X), Y)) --> logic'(X, bitcast(Y)) - Value *CastedOp1 = Builder.CreateBitCast(BO->getOperand(1), DestTy); - return BinaryOperator::Create(BO->getOpcode(), X, CastedOp1); - } - - if (match(BO->getOperand(1), m_OneUse(m_BitCast(m_Value(X)))) && - X->getType() == DestTy && !isa<Constant>(X)) { - // bitcast(logic(Y, bitcast(X))) --> logic'(bitcast(Y), X) - Value *CastedOp0 = Builder.CreateBitCast(BO->getOperand(0), DestTy); - return BinaryOperator::Create(BO->getOpcode(), CastedOp0, X); - } - - // Canonicalize vector bitcasts to come before vector bitwise logic with a - // constant. This eases recognition of special constants for later ops. - // Example: - // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b - Constant *C; - if (match(BO->getOperand(1), m_Constant(C))) { - // bitcast (logic X, C) --> logic (bitcast X, C') - Value *CastedOp0 = Builder.CreateBitCast(BO->getOperand(0), DestTy); - Value *CastedC = ConstantExpr::getBitCast(C, DestTy); - return BinaryOperator::Create(BO->getOpcode(), CastedOp0, CastedC); - } - - return nullptr; -} - -/// Change the type of a select if we can eliminate a bitcast. -static Instruction *foldBitCastSelect(BitCastInst &BitCast, - InstCombiner::BuilderTy &Builder) { - Value *Cond, *TVal, *FVal; - if (!match(BitCast.getOperand(0), - m_OneUse(m_Select(m_Value(Cond), m_Value(TVal), m_Value(FVal))))) - return nullptr; - - // A vector select must maintain the same number of elements in its operands. - Type *CondTy = Cond->getType(); - Type *DestTy = BitCast.getType(); - if (CondTy->isVectorTy()) { - if (!DestTy->isVectorTy()) - return nullptr; - if (DestTy->getVectorNumElements() != CondTy->getVectorNumElements()) - return nullptr; - } - - // FIXME: This transform is restricted from changing the select between - // scalars and vectors to avoid backend problems caused by creating - // potentially illegal operations. If a fix-up is added to handle that - // situation, we can remove this check. - if (DestTy->isVectorTy() != TVal->getType()->isVectorTy()) - return nullptr; - - auto *Sel = cast<Instruction>(BitCast.getOperand(0)); - Value *X; - if (match(TVal, m_OneUse(m_BitCast(m_Value(X)))) && X->getType() == DestTy && - !isa<Constant>(X)) { - // bitcast(select(Cond, bitcast(X), Y)) --> select'(Cond, X, bitcast(Y)) - Value *CastedVal = Builder.CreateBitCast(FVal, DestTy); - return SelectInst::Create(Cond, X, CastedVal, "", nullptr, Sel); - } - - if (match(FVal, m_OneUse(m_BitCast(m_Value(X)))) && X->getType() == DestTy && - !isa<Constant>(X)) { - // bitcast(select(Cond, Y, bitcast(X))) --> select'(Cond, bitcast(Y), X) - Value *CastedVal = Builder.CreateBitCast(TVal, DestTy); - return SelectInst::Create(Cond, CastedVal, X, "", nullptr, Sel); - } - - return nullptr; -} - -/// Check if all users of CI are StoreInsts. -static bool hasStoreUsersOnly(CastInst &CI) { - for (User *U : CI.users()) { - if (!isa<StoreInst>(U)) - return false; - } - return true; -} - -/// This function handles following case -/// -/// A -> B cast -/// PHI -/// B -> A cast -/// -/// All the related PHI nodes can be replaced by new PHI nodes with type A. -/// The uses of \p CI can be changed to the new PHI node corresponding to \p PN. -Instruction *InstCombiner::optimizeBitCastFromPhi(CastInst &CI, PHINode *PN) { - // BitCast used by Store can be handled in InstCombineLoadStoreAlloca.cpp. - if (hasStoreUsersOnly(CI)) - return nullptr; - - Value *Src = CI.getOperand(0); - Type *SrcTy = Src->getType(); // Type B - Type *DestTy = CI.getType(); // Type A - - SmallVector<PHINode *, 4> PhiWorklist; - SmallSetVector<PHINode *, 4> OldPhiNodes; - - // Find all of the A->B casts and PHI nodes. - // We need to inspect all related PHI nodes, but PHIs can be cyclic, so - // OldPhiNodes is used to track all known PHI nodes, before adding a new - // PHI to PhiWorklist, it is checked against and added to OldPhiNodes first. - PhiWorklist.push_back(PN); - OldPhiNodes.insert(PN); - while (!PhiWorklist.empty()) { - auto *OldPN = PhiWorklist.pop_back_val(); - for (Value *IncValue : OldPN->incoming_values()) { - if (isa<Constant>(IncValue)) - continue; - - if (auto *LI = dyn_cast<LoadInst>(IncValue)) { - // If there is a sequence of one or more load instructions, each loaded - // value is used as address of later load instruction, bitcast is - // necessary to change the value type, don't optimize it. For - // simplicity we give up if the load address comes from another load. - Value *Addr = LI->getOperand(0); - if (Addr == &CI || isa<LoadInst>(Addr)) - return nullptr; - if (LI->hasOneUse() && LI->isSimple()) - continue; - // If a LoadInst has more than one use, changing the type of loaded - // value may create another bitcast. - return nullptr; - } - - if (auto *PNode = dyn_cast<PHINode>(IncValue)) { - if (OldPhiNodes.insert(PNode)) - PhiWorklist.push_back(PNode); - continue; - } - - auto *BCI = dyn_cast<BitCastInst>(IncValue); - // We can't handle other instructions. - if (!BCI) - return nullptr; - - // Verify it's a A->B cast. - Type *TyA = BCI->getOperand(0)->getType(); - Type *TyB = BCI->getType(); - if (TyA != DestTy || TyB != SrcTy) - return nullptr; - } - } - - // For each old PHI node, create a corresponding new PHI node with a type A. - SmallDenseMap<PHINode *, PHINode *> NewPNodes; - for (auto *OldPN : OldPhiNodes) { - Builder.SetInsertPoint(OldPN); - PHINode *NewPN = Builder.CreatePHI(DestTy, OldPN->getNumOperands()); - NewPNodes[OldPN] = NewPN; - } - - // Fill in the operands of new PHI nodes. - for (auto *OldPN : OldPhiNodes) { - PHINode *NewPN = NewPNodes[OldPN]; - for (unsigned j = 0, e = OldPN->getNumOperands(); j != e; ++j) { - Value *V = OldPN->getOperand(j); - Value *NewV = nullptr; - if (auto *C = dyn_cast<Constant>(V)) { - NewV = ConstantExpr::getBitCast(C, DestTy); - } else if (auto *LI = dyn_cast<LoadInst>(V)) { - Builder.SetInsertPoint(LI->getNextNode()); - NewV = Builder.CreateBitCast(LI, DestTy); - Worklist.Add(LI); - } else if (auto *BCI = dyn_cast<BitCastInst>(V)) { - NewV = BCI->getOperand(0); - } else if (auto *PrevPN = dyn_cast<PHINode>(V)) { - NewV = NewPNodes[PrevPN]; - } - assert(NewV); - NewPN->addIncoming(NewV, OldPN->getIncomingBlock(j)); - } - } - - // Traverse all accumulated PHI nodes and process its users, - // which are Stores and BitcCasts. Without this processing - // NewPHI nodes could be replicated and could lead to extra - // moves generated after DeSSA. - // If there is a store with type B, change it to type A. - - - // Replace users of BitCast B->A with NewPHI. These will help - // later to get rid off a closure formed by OldPHI nodes. - Instruction *RetVal = nullptr; - for (auto *OldPN : OldPhiNodes) { - PHINode *NewPN = NewPNodes[OldPN]; - for (User *V : OldPN->users()) { - if (auto *SI = dyn_cast<StoreInst>(V)) { - if (SI->isSimple() && SI->getOperand(0) == OldPN) { - Builder.SetInsertPoint(SI); - auto *NewBC = - cast<BitCastInst>(Builder.CreateBitCast(NewPN, SrcTy)); - SI->setOperand(0, NewBC); - Worklist.Add(SI); - assert(hasStoreUsersOnly(*NewBC)); - } - } - else if (auto *BCI = dyn_cast<BitCastInst>(V)) { - // Verify it's a B->A cast. - Type *TyB = BCI->getOperand(0)->getType(); - Type *TyA = BCI->getType(); - if (TyA == DestTy && TyB == SrcTy) { - Instruction *I = replaceInstUsesWith(*BCI, NewPN); - if (BCI == &CI) - RetVal = I; - } - } - } - } - - return RetVal; -} - -Instruction *InstCombiner::visitBitCast(BitCastInst &CI) { - // If the operands are integer typed then apply the integer transforms, - // otherwise just apply the common ones. - Value *Src = CI.getOperand(0); - Type *SrcTy = Src->getType(); - Type *DestTy = CI.getType(); - - // Get rid of casts from one type to the same type. These are useless and can - // be replaced by the operand. - if (DestTy == Src->getType()) - return replaceInstUsesWith(CI, Src); - - if (PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) { - PointerType *SrcPTy = cast<PointerType>(SrcTy); - Type *DstElTy = DstPTy->getElementType(); - Type *SrcElTy = SrcPTy->getElementType(); - - // Casting pointers between the same type, but with different address spaces - // is an addrspace cast rather than a bitcast. - if ((DstElTy == SrcElTy) && - (DstPTy->getAddressSpace() != SrcPTy->getAddressSpace())) - return new AddrSpaceCastInst(Src, DestTy); - - // If we are casting a alloca to a pointer to a type of the same - // size, rewrite the allocation instruction to allocate the "right" type. - // There is no need to modify malloc calls because it is their bitcast that - // needs to be cleaned up. - if (AllocaInst *AI = dyn_cast<AllocaInst>(Src)) - if (Instruction *V = PromoteCastOfAllocation(CI, *AI)) - return V; - - // When the type pointed to is not sized the cast cannot be - // turned into a gep. - Type *PointeeType = - cast<PointerType>(Src->getType()->getScalarType())->getElementType(); - if (!PointeeType->isSized()) - return nullptr; - - // If the source and destination are pointers, and this cast is equivalent - // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep. - // This can enhance SROA and other transforms that want type-safe pointers. - unsigned NumZeros = 0; - while (SrcElTy != DstElTy && - isa<CompositeType>(SrcElTy) && !SrcElTy->isPointerTy() && - SrcElTy->getNumContainedTypes() /* not "{}" */) { - SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(0U); - ++NumZeros; - } - - // If we found a path from the src to dest, create the getelementptr now. - if (SrcElTy == DstElTy) { - SmallVector<Value *, 8> Idxs(NumZeros + 1, Builder.getInt32(0)); - return GetElementPtrInst::CreateInBounds(SrcPTy->getElementType(), Src, - Idxs); - } - } - - if (VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) { - if (DestVTy->getNumElements() == 1 && !SrcTy->isVectorTy()) { - Value *Elem = Builder.CreateBitCast(Src, DestVTy->getElementType()); - return InsertElementInst::Create(UndefValue::get(DestTy), Elem, - Constant::getNullValue(Type::getInt32Ty(CI.getContext()))); - // FIXME: Canonicalize bitcast(insertelement) -> insertelement(bitcast) - } - - if (isa<IntegerType>(SrcTy)) { - // If this is a cast from an integer to vector, check to see if the input - // is a trunc or zext of a bitcast from vector. If so, we can replace all - // the casts with a shuffle and (potentially) a bitcast. - if (isa<TruncInst>(Src) || isa<ZExtInst>(Src)) { - CastInst *SrcCast = cast<CastInst>(Src); - if (BitCastInst *BCIn = dyn_cast<BitCastInst>(SrcCast->getOperand(0))) - if (isa<VectorType>(BCIn->getOperand(0)->getType())) - if (Instruction *I = optimizeVectorResize(BCIn->getOperand(0), - cast<VectorType>(DestTy), *this)) - return I; - } - - // If the input is an 'or' instruction, we may be doing shifts and ors to - // assemble the elements of the vector manually. Try to rip the code out - // and replace it with insertelements. - if (Value *V = optimizeIntegerToVectorInsertions(CI, *this)) - return replaceInstUsesWith(CI, V); - } - } - - if (VectorType *SrcVTy = dyn_cast<VectorType>(SrcTy)) { - if (SrcVTy->getNumElements() == 1) { - // If our destination is not a vector, then make this a straight - // scalar-scalar cast. - if (!DestTy->isVectorTy()) { - Value *Elem = - Builder.CreateExtractElement(Src, - Constant::getNullValue(Type::getInt32Ty(CI.getContext()))); - return CastInst::Create(Instruction::BitCast, Elem, DestTy); - } - - // Otherwise, see if our source is an insert. If so, then use the scalar - // component directly: - // bitcast (inselt <1 x elt> V, X, 0) to <n x m> --> bitcast X to <n x m> - if (auto *InsElt = dyn_cast<InsertElementInst>(Src)) - return new BitCastInst(InsElt->getOperand(1), DestTy); - } - } - - if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) { - // Okay, we have (bitcast (shuffle ..)). Check to see if this is - // a bitcast to a vector with the same # elts. - if (SVI->hasOneUse() && DestTy->isVectorTy() && - DestTy->getVectorNumElements() == SVI->getType()->getNumElements() && - SVI->getType()->getNumElements() == - SVI->getOperand(0)->getType()->getVectorNumElements()) { - BitCastInst *Tmp; - // If either of the operands is a cast from CI.getType(), then - // evaluating the shuffle in the casted destination's type will allow - // us to eliminate at least one cast. - if (((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(0))) && - Tmp->getOperand(0)->getType() == DestTy) || - ((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(1))) && - Tmp->getOperand(0)->getType() == DestTy)) { - Value *LHS = Builder.CreateBitCast(SVI->getOperand(0), DestTy); - Value *RHS = Builder.CreateBitCast(SVI->getOperand(1), DestTy); - // Return a new shuffle vector. Use the same element ID's, as we - // know the vector types match #elts. - return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2)); - } - } - } - - // Handle the A->B->A cast, and there is an intervening PHI node. - if (PHINode *PN = dyn_cast<PHINode>(Src)) - if (Instruction *I = optimizeBitCastFromPhi(CI, PN)) - return I; - - if (Instruction *I = canonicalizeBitCastExtElt(CI, *this)) - return I; - - if (Instruction *I = foldBitCastBitwiseLogic(CI, Builder)) - return I; - - if (Instruction *I = foldBitCastSelect(CI, Builder)) - return I; - - if (SrcTy->isPointerTy()) - return commonPointerCastTransforms(CI); - return commonCastTransforms(CI); -} - -Instruction *InstCombiner::visitAddrSpaceCast(AddrSpaceCastInst &CI) { - // If the destination pointer element type is not the same as the source's - // first do a bitcast to the destination type, and then the addrspacecast. - // This allows the cast to be exposed to other transforms. - Value *Src = CI.getOperand(0); - PointerType *SrcTy = cast<PointerType>(Src->getType()->getScalarType()); - PointerType *DestTy = cast<PointerType>(CI.getType()->getScalarType()); - - Type *DestElemTy = DestTy->getElementType(); - if (SrcTy->getElementType() != DestElemTy) { - Type *MidTy = PointerType::get(DestElemTy, SrcTy->getAddressSpace()); - if (VectorType *VT = dyn_cast<VectorType>(CI.getType())) { - // Handle vectors of pointers. - MidTy = VectorType::get(MidTy, VT->getNumElements()); - } - - Value *NewBitCast = Builder.CreateBitCast(Src, MidTy); - return new AddrSpaceCastInst(NewBitCast, CI.getType()); - } - - return commonPointerCastTransforms(CI); -} |