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Diffstat (limited to 'contrib/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp')
| -rw-r--r-- | contrib/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp | 1862 |
1 files changed, 1862 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/contrib/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp new file mode 100644 index 000000000000..72377dc0adca --- /dev/null +++ b/contrib/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp @@ -0,0 +1,1862 @@ +//===- InstCombineCasts.cpp -----------------------------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements the visit functions for cast operations. +// +//===----------------------------------------------------------------------===// + +#include "InstCombine.h" +#include "llvm/Analysis/ConstantFolding.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/Support/PatternMatch.h" +#include "llvm/Target/TargetLibraryInfo.h" +using namespace llvm; +using namespace PatternMatch; + +/// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear +/// expression. If so, decompose it, returning some value X, such that Val is +/// X*Scale+Offset. +/// +static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale, + 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; +} + +/// PromoteCastOfAllocation - If we find a cast of an allocation instruction, +/// try to eliminate the cast by moving the type information into the alloc. +Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI, + AllocaInst &AI) { + // This requires DataLayout to get the alloca alignment and size information. + if (!TD) return 0; + + PointerType *PTy = cast<PointerType>(CI.getType()); + + BuilderTy AllocaBuilder(*Builder); + AllocaBuilder.SetInsertPoint(AI.getParent(), &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 0; + + unsigned AllocElTyAlign = TD->getABITypeAlignment(AllocElTy); + unsigned CastElTyAlign = TD->getABITypeAlignment(CastElTy); + if (CastElTyAlign < AllocElTyAlign) return 0; + + // If the allocation has multiple uses, only promote it if we are strictly + // increasing the alignment of the resultant allocation. If we keep it the + // same, we open the door to infinite loops of various kinds. + if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return 0; + + uint64_t AllocElTySize = TD->getTypeAllocSize(AllocElTy); + uint64_t CastElTySize = TD->getTypeAllocSize(CastElTy); + if (CastElTySize == 0 || AllocElTySize == 0) return 0; + + // If the allocation has multiple uses, only promote it if we're not + // shrinking the amount of memory being allocated. + uint64_t AllocElTyStoreSize = TD->getTypeStoreSize(AllocElTy); + uint64_t CastElTyStoreSize = TD->getTypeStoreSize(CastElTy); + if (!AI.hasOneUse() && CastElTyStoreSize < AllocElTyStoreSize) return 0; + + // 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 0; + + unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize; + Value *Amt = 0; + 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); + + // 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); +} + +/// EvaluateInDifferentType - 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 TD info. + if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) + C = ConstantFoldConstantExpression(CE, TD, TLI); + return C; + } + + // Otherwise, it must be an instruction. + Instruction *I = cast<Instruction>(V); + Instruction *Res = 0; + unsigned Opc = I->getOpcode(); + switch (Opc) { + case Instruction::Add: + case Instruction::Sub: + case Instruction::Mul: + case Instruction::And: + case Instruction::Or: + case Instruction::Xor: + case Instruction::AShr: + case Instruction::LShr: + case Instruction::Shl: + case Instruction::UDiv: + case Instruction::URem: { + Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned); + Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned); + Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS); + break; + } + case Instruction::Trunc: + case Instruction::ZExt: + case Instruction::SExt: + // If the source type of the cast is the type we're trying for then we can + // just return the source. There's no need to insert it because it is not + // new. + if (I->getOperand(0)->getType() == Ty) + return I->getOperand(0); + + // Otherwise, must be the same type of cast, so just reinsert a new one. + // 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); +} + + +/// This function is a wrapper around CastInst::isEliminableCastPair. It +/// simply extracts arguments and returns what that function returns. +static Instruction::CastOps +isEliminableCastPair( + const CastInst *CI, ///< The first cast instruction + unsigned opcode, ///< The opcode of the second cast instruction + Type *DstTy, ///< The target type for the second cast instruction + DataLayout *TD ///< The target data for pointer size +) { + + Type *SrcTy = CI->getOperand(0)->getType(); // A from above + Type *MidTy = CI->getType(); // B from above + + // Get the opcodes of the two Cast instructions + Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode()); + Instruction::CastOps secondOp = Instruction::CastOps(opcode); + Type *SrcIntPtrTy = TD && SrcTy->isPtrOrPtrVectorTy() ? + TD->getIntPtrType(SrcTy) : 0; + Type *MidIntPtrTy = TD && MidTy->isPtrOrPtrVectorTy() ? + TD->getIntPtrType(MidTy) : 0; + Type *DstIntPtrTy = TD && DstTy->isPtrOrPtrVectorTy() ? + TD->getIntPtrType(DstTy) : 0; + 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); +} + +/// ShouldOptimizeCast - Return true if the cast from "V to Ty" actually +/// results in any code being generated and is interesting to optimize out. If +/// the cast can be eliminated by some other simple transformation, we prefer +/// to do the simplification first. +bool InstCombiner::ShouldOptimizeCast(Instruction::CastOps opc, const Value *V, + Type *Ty) { + // Noop casts and casts of constants should be eliminated trivially. + if (V->getType() == Ty || isa<Constant>(V)) return false; + + // If this is another cast that can be eliminated, we prefer to have it + // eliminated. + if (const CastInst *CI = dyn_cast<CastInst>(V)) + if (isEliminableCastPair(CI, opc, Ty, TD)) + return false; + + // If this is a vector sext from a compare, then we don't want to break the + // idiom where each element of the extended vector is either zero or all ones. + if (opc == Instruction::SExt && isa<CmpInst>(V) && Ty->isVectorTy()) + return false; + + return true; +} + + +/// @brief Implement the transforms common to all CastInst visitors. +Instruction *InstCombiner::commonCastTransforms(CastInst &CI) { + Value *Src = CI.getOperand(0); + + // Many cases of "cast of a cast" are eliminable. If it's eliminable we just + // eliminate it now. + if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast + if (Instruction::CastOps opc = + isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), TD)) { + // The first cast (CSrc) is eliminable so we need to fix up or replace + // the second cast (CI). CSrc will then have a good chance of being dead. + return CastInst::Create(opc, CSrc->getOperand(0), CI.getType()); + } + } + + // If we are casting a select then fold the cast into the select + if (SelectInst *SI = dyn_cast<SelectInst>(Src)) + if (Instruction *NV = FoldOpIntoSelect(CI, SI)) + return NV; + + // If we are casting a PHI then fold the cast into the PHI + if (isa<PHINode>(Src)) { + // We don't do this if this would create a PHI node with an illegal type if + // it is currently legal. + if (!Src->getType()->isIntegerTy() || + !CI.getType()->isIntegerTy() || + ShouldChangeType(CI.getType(), Src->getType())) + if (Instruction *NV = FoldOpIntoPhi(CI)) + return NV; + } + + return 0; +} + +/// CanEvaluateTruncated - 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) { + // We can always evaluate constants in another type. + if (isa<Constant>(V)) + return true; + + Instruction *I = dyn_cast<Instruction>(V); + if (!I) return false; + + Type *OrigTy = V->getType(); + + // If this is an extension from the dest type, we can eliminate it, even if it + // has multiple uses. + if ((isa<ZExtInst>(I) || isa<SExtInst>(I)) && + I->getOperand(0)->getType() == Ty) + return true; + + // We can't extend or shrink something that has multiple uses: doing so would + // require duplicating the instruction in general, which isn't profitable. + if (!I->hasOneUse()) return false; + + unsigned Opc = I->getOpcode(); + switch (Opc) { + case Instruction::Add: + case Instruction::Sub: + case Instruction::Mul: + case Instruction::And: + case Instruction::Or: + case Instruction::Xor: + // These operators can all arbitrarily be extended or truncated. + return CanEvaluateTruncated(I->getOperand(0), Ty) && + CanEvaluateTruncated(I->getOperand(1), Ty); + + case Instruction::UDiv: + case Instruction::URem: { + // UDiv and URem can be truncated if all the truncated bits are zero. + uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits(); + uint32_t BitWidth = Ty->getScalarSizeInBits(); + if (BitWidth < OrigBitWidth) { + APInt Mask = APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth); + if (MaskedValueIsZero(I->getOperand(0), Mask) && + MaskedValueIsZero(I->getOperand(1), Mask)) { + return CanEvaluateTruncated(I->getOperand(0), Ty) && + CanEvaluateTruncated(I->getOperand(1), Ty); + } + } + break; + } + case Instruction::Shl: + // If we are truncating the result of this SHL, and if it's a shift of a + // constant amount, we can always perform a SHL in a smaller type. + if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) { + uint32_t BitWidth = Ty->getScalarSizeInBits(); + if (CI->getLimitedValue(BitWidth) < BitWidth) + return CanEvaluateTruncated(I->getOperand(0), Ty); + } + break; + case Instruction::LShr: + // If this is a truncate of a logical shr, we can truncate it to a smaller + // lshr iff we know that the bits we would otherwise be shifting in are + // already zeros. + if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) { + uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits(); + uint32_t BitWidth = Ty->getScalarSizeInBits(); + if (MaskedValueIsZero(I->getOperand(0), + APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) && + CI->getLimitedValue(BitWidth) < BitWidth) { + return CanEvaluateTruncated(I->getOperand(0), Ty); + } + } + 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) && + CanEvaluateTruncated(SI->getFalseValue(), 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 (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) + if (!CanEvaluateTruncated(PN->getIncomingValue(i), Ty)) + return false; + return true; + } + default: + // TODO: Can handle more cases here. + break; + } + + return false; +} + +Instruction *InstCombiner::visitTrunc(TruncInst &CI) { + if (Instruction *Result = commonCastTransforms(CI)) + return Result; + + // 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; + + 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)) { + + // If this cast is a truncate, evaluting in a different type always + // eliminates the cast, so it is always a win. + 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); + } + + // Canonicalize trunc x to i1 -> (icmp ne (and x, 1), 0), likewise for vector. + if (DestTy->getScalarSizeInBits() == 1) { + Constant *One = ConstantInt::get(Src->getType(), 1); + Src = Builder->CreateAnd(Src, One); + Value *Zero = Constant::getNullValue(Src->getType()); + return new ICmpInst(ICmpInst::ICMP_NE, Src, Zero); + } + + // Transform trunc(lshr (zext A), Cst) to eliminate one type conversion. + Value *A = 0; ConstantInt *Cst = 0; + 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(CI.getType())); + + // 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, CI.getType(), false); + } + + // Transform "trunc (and X, cst)" -> "and (trunc X), cst" so long as the dest + // type isn't non-native. + if (Src->hasOneUse() && isa<IntegerType>(Src->getType()) && + ShouldChangeType(Src->getType(), CI.getType()) && + match(Src, m_And(m_Value(A), m_ConstantInt(Cst)))) { + Value *NewTrunc = Builder->CreateTrunc(A, CI.getType(), A->getName()+".tr"); + return BinaryOperator::CreateAnd(NewTrunc, + ConstantExpr::getTrunc(Cst, CI.getType())); + } + + return 0; +} + +/// transformZExtICmp - Transform (zext icmp) to bitwise / integer operations +/// in order to eliminate the icmp. +Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, Instruction &CI, + bool DoXform) { + // If we are just checking for a icmp eq of a single bit and zext'ing it + // to an integer, then shift the bit to the appropriate place and then + // cast to integer to avoid the comparison. + if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) { + const APInt &Op1CV = Op1C->getValue(); + + // zext (x <s 0) to i32 --> x>>u31 true if signbit set. + // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear. + if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) || + (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())) { + if (!DoXform) return ICI; + + Value *In = ICI->getOperand(0); + Value *Sh = ConstantInt::get(In->getType(), + In->getType()->getScalarSizeInBits()-1); + In = Builder->CreateLShr(In, Sh, In->getName()+".lobit"); + if (In->getType() != CI.getType()) + In = Builder->CreateIntCast(In, CI.getType(), false/*ZExt*/); + + if (ICI->getPredicate() == ICmpInst::ICMP_SGT) { + Constant *One = ConstantInt::get(In->getType(), 1); + In = Builder->CreateXor(In, One, In->getName()+".not"); + } + + return ReplaceInstUsesWith(CI, In); + } + + // zext (X == 0) to i32 --> X^1 iff X has only the low bit set. + // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set. + // zext (X == 1) to i32 --> X iff X has only the low bit set. + // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set. + // zext (X != 0) to i32 --> X iff X has only the low bit set. + // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set. + // zext (X != 1) to i32 --> X^1 iff X has only the low bit set. + // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set. + if ((Op1CV == 0 || Op1CV.isPowerOf2()) && + // This only works for EQ and NE + ICI->isEquality()) { + // If Op1C some other power of two, convert: + uint32_t BitWidth = Op1C->getType()->getBitWidth(); + APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); + ComputeMaskedBits(ICI->getOperand(0), KnownZero, KnownOne); + + APInt KnownZeroMask(~KnownZero); + if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1? + if (!DoXform) return ICI; + + bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE; + if (Op1CV != 0 && (Op1CV != KnownZeroMask)) { + // (X&4) == 2 --> false + // (X&4) != 2 --> true + Constant *Res = ConstantInt::get(Type::getInt1Ty(CI.getContext()), + isNE); + Res = ConstantExpr::getZExt(Res, CI.getType()); + return ReplaceInstUsesWith(CI, Res); + } + + uint32_t ShiftAmt = KnownZeroMask.logBase2(); + Value *In = ICI->getOperand(0); + if (ShiftAmt) { + // Perform a logical shr by shiftamt. + // Insert the shift to put the result in the low bit. + In = Builder->CreateLShr(In, ConstantInt::get(In->getType(),ShiftAmt), + In->getName()+".lobit"); + } + + if ((Op1CV != 0) == isNE) { // Toggle the low bit. + Constant *One = ConstantInt::get(In->getType(), 1); + In = Builder->CreateXor(In, One); + } + + if (CI.getType() == In->getType()) + return ReplaceInstUsesWith(CI, In); + return CastInst::CreateIntegerCast(In, CI.getType(), false/*ZExt*/); + } + } + } + + // icmp ne A, B is equal to xor A, B when A and B only really have one bit. + // It is also profitable to transform icmp eq into not(xor(A, B)) because that + // may lead to additional simplifications. + if (ICI->isEquality() && CI.getType() == ICI->getOperand(0)->getType()) { + if (IntegerType *ITy = dyn_cast<IntegerType>(CI.getType())) { + uint32_t BitWidth = ITy->getBitWidth(); + Value *LHS = ICI->getOperand(0); + Value *RHS = ICI->getOperand(1); + + APInt KnownZeroLHS(BitWidth, 0), KnownOneLHS(BitWidth, 0); + APInt KnownZeroRHS(BitWidth, 0), KnownOneRHS(BitWidth, 0); + ComputeMaskedBits(LHS, KnownZeroLHS, KnownOneLHS); + ComputeMaskedBits(RHS, KnownZeroRHS, KnownOneRHS); + + if (KnownZeroLHS == KnownZeroRHS && KnownOneLHS == KnownOneRHS) { + APInt KnownBits = KnownZeroLHS | KnownOneLHS; + APInt UnknownBit = ~KnownBits; + if (UnknownBit.countPopulation() == 1) { + if (!DoXform) return ICI; + + Value *Result = Builder->CreateXor(LHS, RHS); + + // Mask off any bits that are set and won't be shifted away. + if (KnownOneLHS.uge(UnknownBit)) + Result = Builder->CreateAnd(Result, + ConstantInt::get(ITy, UnknownBit)); + + // Shift the bit we're testing down to the lsb. + Result = Builder->CreateLShr( + Result, ConstantInt::get(ITy, UnknownBit.countTrailingZeros())); + + if (ICI->getPredicate() == ICmpInst::ICMP_EQ) + Result = Builder->CreateXor(Result, ConstantInt::get(ITy, 1)); + Result->takeName(ICI); + return ReplaceInstUsesWith(CI, Result); + } + } + } + } + + return 0; +} + +/// CanEvaluateZExtd - 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) { + BitsToClear = 0; + if (isa<Constant>(V)) + return true; + + Instruction *I = dyn_cast<Instruction>(V); + if (!I) return false; + + // If the input is a truncate from the destination type, we can trivially + // eliminate it. + if (isa<TruncInst>(I) && I->getOperand(0)->getType() == Ty) + return true; + + // We can't extend or shrink something that has multiple uses: doing so would + // require duplicating the instruction in general, which isn't profitable. + if (!I->hasOneUse()) return false; + + unsigned Opc = I->getOpcode(), Tmp; + switch (Opc) { + 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) || + !CanEvaluateZExtd(I->getOperand(1), Ty, Tmp)) + 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 && + (Opc == Instruction::And || Opc == Instruction::Or || + Opc == Instruction::Xor)) { + // We use MaskedValueIsZero here for generality, but the case we care + // about the most is constant RHS. + unsigned VSize = V->getType()->getScalarSizeInBits(); + if (MaskedValueIsZero(I->getOperand(1), + APInt::getHighBitsSet(VSize, BitsToClear))) + 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. + if (ConstantInt *Amt = dyn_cast<ConstantInt>(I->getOperand(1))) { + if (!CanEvaluateZExtd(I->getOperand(0), Ty, BitsToClear)) + 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. + if (ConstantInt *Amt = dyn_cast<ConstantInt>(I->getOperand(1))) { + if (!CanEvaluateZExtd(I->getOperand(0), Ty, BitsToClear)) + 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) || + !CanEvaluateZExtd(I->getOperand(2), Ty, BitsToClear) || + // 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)) + return false; + for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) + if (!CanEvaluateZExtd(PN->getIncomingValue(i), Ty, Tmp) || + // 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.use_back())) + return 0; + + // If one of the common conversion will work, do it. + if (Instruction *Result = commonCastTransforms(CI)) + return Result; + + // 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; + + Value *Src = CI.getOperand(0); + Type *SrcTy = Src->getType(), *DestTy = CI.getType(); + + // Attempt to extend 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. + unsigned BitsToClear; + if ((DestTy->isVectorTy() || ShouldChangeType(SrcTy, DestTy)) && + CanEvaluateZExtd(Src, DestTy, BitsToClear)) { + assert(BitsToClear < SrcTy->getScalarSizeInBits() && + "Unreasonable BitsToClear"); + + // Okay, we can transform this! Insert the new expression now. + DEBUG(dbgs() << "ICE: EvaluateInDifferentType converting expression type" + " to avoid zero extend: " << CI); + Value *Res = EvaluateInDifferentType(Src, DestTy, false); + assert(Res->getType() == DestTy); + + 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))) + 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) will be transformed. + ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0)); + ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1)); + if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() && + (transformZExtICmp(LHS, CI, false) || + transformZExtICmp(RHS, CI, false))) { + Value *LCast = Builder->CreateZExt(LHS, CI.getType(), LHS->getName()); + Value *RCast = Builder->CreateZExt(RHS, CI.getType(), RHS->getName()); + return BinaryOperator::Create(Instruction::Or, LCast, RCast); + } + } + + // zext(trunc(t) & C) -> (t & zext(C)). + if (SrcI && SrcI->getOpcode() == Instruction::And && SrcI->hasOneUse()) + if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1))) + if (TruncInst *TI = dyn_cast<TruncInst>(SrcI->getOperand(0))) { + Value *TI0 = TI->getOperand(0); + if (TI0->getType() == CI.getType()) + return + BinaryOperator::CreateAnd(TI0, + ConstantExpr::getZExt(C, CI.getType())); + } + + // zext((trunc(t) & C) ^ C) -> ((t & zext(C)) ^ zext(C)). + if (SrcI && SrcI->getOpcode() == Instruction::Xor && SrcI->hasOneUse()) + if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1))) + if (BinaryOperator *And = dyn_cast<BinaryOperator>(SrcI->getOperand(0))) + if (And->getOpcode() == Instruction::And && And->hasOneUse() && + And->getOperand(1) == C) + if (TruncInst *TI = dyn_cast<TruncInst>(And->getOperand(0))) { + Value *TI0 = TI->getOperand(0); + if (TI0->getType() == CI.getType()) { + Constant *ZC = ConstantExpr::getZExt(C, CI.getType()); + Value *NewAnd = Builder->CreateAnd(TI0, ZC); + return BinaryOperator::CreateXor(NewAnd, ZC); + } + } + + // zext (xor i1 X, true) to i32 --> xor (zext i1 X to i32), 1 + Value *X; + if (SrcI && SrcI->hasOneUse() && SrcI->getType()->isIntegerTy(1) && + match(SrcI, m_Not(m_Value(X))) && + (!X->hasOneUse() || !isa<CmpInst>(X))) { + Value *New = Builder->CreateZExt(X, CI.getType()); + return BinaryOperator::CreateXor(New, ConstantInt::get(CI.getType(), 1)); + } + + return 0; +} + +/// transformSExtICmp - Transform (sext icmp) to bitwise / integer operations +/// in order 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(); + + if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) { + // (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 + if ((Pred == ICmpInst::ICMP_SLT && Op1C->isZero()) || + (Pred == ICmpInst::ICMP_SGT && Op1C->isAllOnesValue())) { + + 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 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())){ + unsigned BitWidth = Op1C->getType()->getBitWidth(); + APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); + ComputeMaskedBits(Op0, KnownZero, KnownOne); + + APInt KnownZeroMask(~KnownZero); + 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(), + BitWidth - 1), "sext"); + } + + if (CI.getType() == In->getType()) + return ReplaceInstUsesWith(CI, In); + return CastInst::CreateIntegerCast(In, CI.getType(), true/*SExt*/); + } + } + } + + // vector (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if signed. + if (VectorType *VTy = dyn_cast<VectorType>(CI.getType())) { + if (Pred == ICmpInst::ICMP_SLT && match(Op1, m_Zero()) && + Op0->getType() == CI.getType()) { + Type *EltTy = VTy->getElementType(); + + // splat the shift constant to a constant vector. + Constant *VSh = ConstantInt::get(VTy, EltTy->getScalarSizeInBits()-1); + Value *In = Builder->CreateAShr(Op0, VSh, Op0->getName()+".lobit"); + return ReplaceInstUsesWith(CI, In); + } + } + + return 0; +} + +/// CanEvaluateSExtd - 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 this is a constant, it can be trivially promoted. + if (isa<Constant>(V)) + return true; + + Instruction *I = dyn_cast<Instruction>(V); + if (!I) return false; + + // If this is a truncate from the dest type, we can trivially eliminate it. + if (isa<TruncInst>(I) && I->getOperand(0)->getType() == Ty) + return true; + + // We can't extend or shrink something that has multiple uses: doing so would + // require duplicating the instruction in general, which isn't profitable. + if (!I->hasOneUse()) return false; + + 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 (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) + if (!CanEvaluateSExtd(PN->getIncomingValue(i), 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.use_back())) + return 0; + + if (Instruction *I = commonCastTransforms(CI)) + return I; + + // 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; + + Value *Src = CI.getOperand(0); + Type *SrcTy = Src->getType(), *DestTy = CI.getType(); + + // Attempt to extend 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)) && + CanEvaluateSExtd(Src, DestTy)) { + // Okay, we can transform this! Insert the new expression now. + DEBUG(dbgs() << "ICE: EvaluateInDifferentType converting expression type" + " to avoid sign extend: " << CI); + 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) > 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 this input is a trunc from our destination, then turn sext(trunc(x)) + // into shifts. + if (TruncInst *TI = dyn_cast<TruncInst>(Src)) + if (TI->hasOneUse() && TI->getOperand(0)->getType() == DestTy) { + uint32_t SrcBitSize = SrcTy->getScalarSizeInBits(); + uint32_t DestBitSize = DestTy->getScalarSizeInBits(); + + // We need to emit a shl + ashr to do the sign extend. + Value *ShAmt = ConstantInt::get(DestTy, DestBitSize-SrcBitSize); + Value *Res = Builder->CreateShl(TI->getOperand(0), ShAmt, "sext"); + return BinaryOperator::CreateAShr(Res, 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 = 0; + // TODO: Eventually this could be subsumed by EvaluateInDifferentType. + ConstantInt *BA = 0, *CA = 0; + 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 0; +} + + +/// FitsInFPType - Return a Constant* for the specified FP constant if it fits +/// in the specified FP type without changing its value. +static Constant *FitsInFPType(ConstantFP *CFP, const fltSemantics &Sem) { + bool losesInfo; + APFloat F = CFP->getValueAPF(); + (void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo); + if (!losesInfo) + return ConstantFP::get(CFP->getContext(), F); + return 0; +} + +/// LookThroughFPExtensions - If this is an fp extension instruction, look +/// through it until we get the source value. +static Value *LookThroughFPExtensions(Value *V) { + if (Instruction *I = dyn_cast<Instruction>(V)) + if (I->getOpcode() == Instruction::FPExt) + return LookThroughFPExtensions(I->getOperand(0)); + + // If this value is a constant, return the constant in the smallest FP type + // that can accurately represent it. This allows us to turn + // (float)((double)X+2.0) into x+2.0f. + if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) { + if (CFP->getType() == Type::getPPC_FP128Ty(V->getContext())) + return V; // No constant folding of this. + // See if the value can be truncated to half and then reextended. + if (Value *V = FitsInFPType(CFP, APFloat::IEEEhalf)) + return V; + // See if the value can be truncated to float and then reextended. + if (Value *V = FitsInFPType(CFP, APFloat::IEEEsingle)) + return V; + if (CFP->getType()->isDoubleTy()) + return V; // Won't shrink. + if (Value *V = FitsInFPType(CFP, APFloat::IEEEdouble)) + return V; + // Don't try to shrink to various long double types. + } + + return V; +} + +Instruction *InstCombiner::visitFPTrunc(FPTruncInst &CI) { + if (Instruction *I = commonCastTransforms(CI)) + return I; + + // If we have fptrunc(fadd (fpextend x), (fpextend y)), where x and y are + // smaller than the destination type, we can eliminate the truncate by doing + // the add as the smaller type. This applies to fadd/fsub/fmul/fdiv as well + // as many builtins (sqrt, etc). + BinaryOperator *OpI = dyn_cast<BinaryOperator>(CI.getOperand(0)); + if (OpI && OpI->hasOneUse()) { + switch (OpI->getOpcode()) { + default: break; + case Instruction::FAdd: + case Instruction::FSub: + case Instruction::FMul: + case Instruction::FDiv: + case Instruction::FRem: + Type *SrcTy = OpI->getType(); + Value *LHSTrunc = LookThroughFPExtensions(OpI->getOperand(0)); + Value *RHSTrunc = LookThroughFPExtensions(OpI->getOperand(1)); + if (LHSTrunc->getType() != SrcTy && + RHSTrunc->getType() != SrcTy) { + unsigned DstSize = CI.getType()->getScalarSizeInBits(); + // If the source types were both smaller than the destination type of + // the cast, do this xform. + if (LHSTrunc->getType()->getScalarSizeInBits() <= DstSize && + RHSTrunc->getType()->getScalarSizeInBits() <= DstSize) { + LHSTrunc = Builder->CreateFPExt(LHSTrunc, CI.getType()); + RHSTrunc = Builder->CreateFPExt(RHSTrunc, CI.getType()); + return BinaryOperator::Create(OpI->getOpcode(), LHSTrunc, RHSTrunc); + } + } + break; + } + + // (fptrunc (fneg x)) -> (fneg (fptrunc x)) + if (BinaryOperator::isFNeg(OpI)) { + Value *InnerTrunc = Builder->CreateFPTrunc(OpI->getOperand(1), + CI.getType()); + return BinaryOperator::CreateFNeg(InnerTrunc); + } + } + + // (fptrunc (select cond, R1, Cst)) --> + // (select cond, (fptrunc R1), (fptrunc Cst)) + SelectInst *SI = dyn_cast<SelectInst>(CI.getOperand(0)); + if (SI && + (isa<ConstantFP>(SI->getOperand(1)) || + isa<ConstantFP>(SI->getOperand(2)))) { + Value *LHSTrunc = Builder->CreateFPTrunc(SI->getOperand(1), + CI.getType()); + Value *RHSTrunc = Builder->CreateFPTrunc(SI->getOperand(2), + CI.getType()); + return SelectInst::Create(SI->getOperand(0), LHSTrunc, RHSTrunc); + } + + IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI.getOperand(0)); + if (II) { + switch (II->getIntrinsicID()) { + default: break; + case Intrinsic::fabs: { + // (fptrunc (fabs x)) -> (fabs (fptrunc x)) + Value *InnerTrunc = Builder->CreateFPTrunc(II->getArgOperand(0), + CI.getType()); + Type *IntrinsicType[] = { CI.getType() }; + Function *Overload = + Intrinsic::getDeclaration(CI.getParent()->getParent()->getParent(), + II->getIntrinsicID(), IntrinsicType); + + Value *Args[] = { InnerTrunc }; + return CallInst::Create(Overload, Args, II->getName()); + } + } + } + + // Fold (fptrunc (sqrt (fpext x))) -> (sqrtf x) + // Note that we restrict this transformation based on + // TLI->has(LibFunc::sqrtf), even for the sqrt intrinsic, because + // TLI->has(LibFunc::sqrtf) is sufficient to guarantee that the + // single-precision intrinsic can be expanded in the backend. + CallInst *Call = dyn_cast<CallInst>(CI.getOperand(0)); + if (Call && Call->getCalledFunction() && TLI->has(LibFunc::sqrtf) && + (Call->getCalledFunction()->getName() == TLI->getName(LibFunc::sqrt) || + Call->getCalledFunction()->getIntrinsicID() == Intrinsic::sqrt) && + Call->getNumArgOperands() == 1 && + Call->hasOneUse()) { + CastInst *Arg = dyn_cast<CastInst>(Call->getArgOperand(0)); + if (Arg && Arg->getOpcode() == Instruction::FPExt && + CI.getType()->isFloatTy() && + Call->getType()->isDoubleTy() && + Arg->getType()->isDoubleTy() && + Arg->getOperand(0)->getType()->isFloatTy()) { + Function *Callee = Call->getCalledFunction(); + Module *M = CI.getParent()->getParent()->getParent(); + Constant *SqrtfFunc = (Callee->getIntrinsicID() == Intrinsic::sqrt) ? + Intrinsic::getDeclaration(M, Intrinsic::sqrt, Builder->getFloatTy()) : + M->getOrInsertFunction("sqrtf", Callee->getAttributes(), + Builder->getFloatTy(), Builder->getFloatTy(), + NULL); + CallInst *ret = CallInst::Create(SqrtfFunc, Arg->getOperand(0), + "sqrtfcall"); + ret->setAttributes(Callee->getAttributes()); + + + // Remove the old Call. With -fmath-errno, it won't get marked readnone. + ReplaceInstUsesWith(*Call, UndefValue::get(Call->getType())); + EraseInstFromFunction(*Call); + return ret; + } + } + + return 0; +} + +Instruction *InstCombiner::visitFPExt(CastInst &CI) { + return commonCastTransforms(CI); +} + +Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) { + Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0)); + if (OpI == 0) + return commonCastTransforms(FI); + + // fptoui(uitofp(X)) --> X + // fptoui(sitofp(X)) --> X + // This is safe if the intermediate type has enough bits in its mantissa to + // accurately represent all values of X. For example, do not do this with + // i64->float->i64. This is also safe for sitofp case, because any negative + // 'X' value would cause an undefined result for the fptoui. + if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) && + OpI->getOperand(0)->getType() == FI.getType() && + (int)FI.getType()->getScalarSizeInBits() < /*extra bit for sign */ + OpI->getType()->getFPMantissaWidth()) + return ReplaceInstUsesWith(FI, OpI->getOperand(0)); + + return commonCastTransforms(FI); +} + +Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) { + Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0)); + if (OpI == 0) + return commonCastTransforms(FI); + + // fptosi(sitofp(X)) --> X + // fptosi(uitofp(X)) --> X + // This is safe if the intermediate type has enough bits in its mantissa to + // accurately represent all values of X. For example, do not do this with + // i64->float->i64. This is also safe for sitofp case, because any negative + // 'X' value would cause an undefined result for the fptoui. + if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) && + OpI->getOperand(0)->getType() == FI.getType() && + (int)FI.getType()->getScalarSizeInBits() <= + OpI->getType()->getFPMantissaWidth()) + return ReplaceInstUsesWith(FI, OpI->getOperand(0)); + + return commonCastTransforms(FI); +} + +Instruction *InstCombiner::visitUIToFP(CastInst &CI) { + return commonCastTransforms(CI); +} + +Instruction *InstCombiner::visitSIToFP(CastInst &CI) { + return commonCastTransforms(CI); +} + +Instruction *InstCombiner::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. + + if (TD) { + unsigned AS = CI.getAddressSpace(); + if (CI.getOperand(0)->getType()->getScalarSizeInBits() != + TD->getPointerSizeInBits(AS)) { + Type *Ty = TD->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 0; +} + +/// @brief Implement the transforms for cast of pointer (bitcast/ptrtoint) +Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) { + Value *Src = CI.getOperand(0); + + if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) { + // If casting the result of a getelementptr instruction with no offset, turn + // this into a cast of the original pointer! + if (GEP->hasAllZeroIndices()) { + // Changing the cast operand is usually not a good idea but it is safe + // here because the pointer operand is being replaced with another + // pointer operand so the opcode doesn't need to change. + Worklist.Add(GEP); + CI.setOperand(0, GEP->getOperand(0)); + return &CI; + } + + if (!TD) + return commonCastTransforms(CI); + + // If the GEP has a single use, and the base pointer is a bitcast, and the + // GEP computes a constant offset, see if we can convert these three + // instructions into fewer. This typically happens with unions and other + // non-type-safe code. + unsigned AS = GEP->getPointerAddressSpace(); + unsigned OffsetBits = TD->getPointerSizeInBits(AS); + APInt Offset(OffsetBits, 0); + BitCastInst *BCI = dyn_cast<BitCastInst>(GEP->getOperand(0)); + if (GEP->hasOneUse() && + BCI && + GEP->accumulateConstantOffset(*TD, Offset)) { + // Get the base pointer input of the bitcast, and the type it points to. + Value *OrigBase = BCI->getOperand(0); + SmallVector<Value*, 8> NewIndices; + if (FindElementAtOffset(OrigBase->getType(), + Offset.getSExtValue(), + NewIndices)) { + // If we were able to index down into an element, create the GEP + // and bitcast the result. This eliminates one bitcast, potentially + // two. + Value *NGEP = cast<GEPOperator>(GEP)->isInBounds() ? + Builder->CreateInBoundsGEP(OrigBase, NewIndices) : + Builder->CreateGEP(OrigBase, NewIndices); + NGEP->takeName(GEP); + + if (isa<BitCastInst>(CI)) + return new BitCastInst(NGEP, CI.getType()); + assert(isa<PtrToIntInst>(CI)); + return new PtrToIntInst(NGEP, CI.getType()); + } + } + } + + return commonCastTransforms(CI); +} + +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. + + if (!TD) + return commonPointerCastTransforms(CI); + + Type *Ty = CI.getType(); + unsigned AS = CI.getPointerAddressSpace(); + + if (Ty->getScalarSizeInBits() == TD->getPointerSizeInBits(AS)) + return commonPointerCastTransforms(CI); + + Type *PtrTy = TD->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); +} + +/// OptimizeVectorResize - 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 0; + + 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(); +} + +/// CollectInsertionElements - 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, InstCombiner &IC) { + 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 (IC.getDataLayout()->isBigEndian()) + ElementIndex = Elements.size() - ElementIndex - 1; + + // Fail if multiple elements are inserted into this slot. + if (Elements[ElementIndex] != 0) + 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, IC); + + // 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, IC)) + return false; + } + return true; + } + + if (!V->hasOneUse()) return false; + + Instruction *I = dyn_cast<Instruction>(V); + if (I == 0) return false; + switch (I->getOpcode()) { + default: return false; // Unhandled case. + case Instruction::BitCast: + return CollectInsertionElements(I->getOperand(0), Shift, + Elements, VecEltTy, IC); + case Instruction::ZExt: + if (!isMultipleOfTypeSize( + I->getOperand(0)->getType()->getPrimitiveSizeInBits(), + VecEltTy)) + return false; + return CollectInsertionElements(I->getOperand(0), Shift, + Elements, VecEltTy, IC); + case Instruction::Or: + return CollectInsertionElements(I->getOperand(0), Shift, + Elements, VecEltTy, IC) && + CollectInsertionElements(I->getOperand(1), Shift, + Elements, VecEltTy, IC); + 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 == 0) return false; + Shift += CI->getZExtValue(); + if (!isMultipleOfTypeSize(Shift, VecEltTy)) return false; + return CollectInsertionElements(I->getOperand(0), Shift, + Elements, VecEltTy, IC); + } + + } +} + + +/// OptimizeIntegerToVectorInsertions - 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) { + // We need to know the target byte order to perform this optimization. + if (!IC.getDataLayout()) return 0; + + 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)) + return 0; + + // 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] == 0) continue; // Unset element. + + Result = IC.Builder->CreateInsertElement(Result, Elements[i], + IC.Builder->getInt32(i)); + } + + return Result; +} + + +/// OptimizeIntToFloatBitCast - See if we can optimize an integer->float/double +/// bitcast. The various long double bitcasts can't get in here. +static Instruction *OptimizeIntToFloatBitCast(BitCastInst &CI,InstCombiner &IC){ + // We need to know the target byte order to perform this optimization. + if (!IC.getDataLayout()) return 0; + + Value *Src = CI.getOperand(0); + Type *DestTy = CI.getType(); + + // If this is a bitcast from int to float, check to see if the int is an + // extraction from a vector. + Value *VecInput = 0; + // bitcast(trunc(bitcast(somevector))) + if (match(Src, m_Trunc(m_BitCast(m_Value(VecInput)))) && + isa<VectorType>(VecInput->getType())) { + VectorType *VecTy = cast<VectorType>(VecInput->getType()); + unsigned DestWidth = DestTy->getPrimitiveSizeInBits(); + + if (VecTy->getPrimitiveSizeInBits() % DestWidth == 0) { + // If the element type of the vector doesn't match the result type, + // bitcast it to be a vector type we can extract from. + if (VecTy->getElementType() != DestTy) { + VecTy = VectorType::get(DestTy, + VecTy->getPrimitiveSizeInBits() / DestWidth); + VecInput = IC.Builder->CreateBitCast(VecInput, VecTy); + } + + unsigned Elt = 0; + if (IC.getDataLayout()->isBigEndian()) + Elt = VecTy->getPrimitiveSizeInBits() / DestWidth - 1; + return ExtractElementInst::Create(VecInput, IC.Builder->getInt32(Elt)); + } + } + + // bitcast(trunc(lshr(bitcast(somevector), cst)) + ConstantInt *ShAmt = 0; + if (match(Src, m_Trunc(m_LShr(m_BitCast(m_Value(VecInput)), + m_ConstantInt(ShAmt)))) && + isa<VectorType>(VecInput->getType())) { + VectorType *VecTy = cast<VectorType>(VecInput->getType()); + unsigned DestWidth = DestTy->getPrimitiveSizeInBits(); + if (VecTy->getPrimitiveSizeInBits() % DestWidth == 0 && + ShAmt->getZExtValue() % DestWidth == 0) { + // If the element type of the vector doesn't match the result type, + // bitcast it to be a vector type we can extract from. + if (VecTy->getElementType() != DestTy) { + VecTy = VectorType::get(DestTy, + VecTy->getPrimitiveSizeInBits() / DestWidth); + VecInput = IC.Builder->CreateBitCast(VecInput, VecTy); + } + + unsigned Elt = ShAmt->getZExtValue() / DestWidth; + if (IC.getDataLayout()->isBigEndian()) + Elt = VecTy->getPrimitiveSizeInBits() / DestWidth - 1 - Elt; + return ExtractElementInst::Create(VecInput, IC.Builder->getInt32(Elt)); + } + } + return 0; +} + +Instruction *InstCombiner::visitBitCast(BitCastInst &CI) { + // If the operands are integer typed then apply the integer transforms, + // otherwise just apply the common ones. + Value *Src = CI.getOperand(0); + 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(); + + // If the address spaces don't match, don't eliminate the bitcast, which is + // required for changing types. + if (SrcPTy->getAddressSpace() != DstPTy->getAddressSpace()) + return 0; + + // If we are casting a alloca to a pointer to a type of the same + // size, rewrite the allocation instruction to allocate the "right" type. + // There is no need to modify malloc calls because it is their bitcast that + // needs to be cleaned up. + if (AllocaInst *AI = dyn_cast<AllocaInst>(Src)) + if (Instruction *V = PromoteCastOfAllocation(CI, *AI)) + return V; + + // If the source and destination are pointers, and this cast is equivalent + // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep. + // This can enhance SROA and other transforms that want type-safe pointers. + Constant *ZeroUInt = + Constant::getNullValue(Type::getInt32Ty(CI.getContext())); + unsigned NumZeros = 0; + while (SrcElTy != DstElTy && + isa<CompositeType>(SrcElTy) && !SrcElTy->isPointerTy() && + SrcElTy->getNumContainedTypes() /* not "{}" */) { + SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt); + ++NumZeros; + } + + // If we found a path from the src to dest, create the getelementptr now. + if (SrcElTy == DstElTy) { + SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt); + return GetElementPtrInst::CreateInBounds(Src, Idxs); + } + } + + // Try to optimize int -> float bitcasts. + if ((DestTy->isFloatTy() || DestTy->isDoubleTy()) && isa<IntegerType>(SrcTy)) + if (Instruction *I = OptimizeIntToFloatBitCast(CI, *this)) + return I; + + 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. + if (InsertElementInst *IEI = + dyn_cast<InsertElementInst>(CI.getOperand(0))) + return CastInst::Create(Instruction::BitCast, IEI->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)); + } + } + } + + if (SrcTy->isPointerTy()) + return commonPointerCastTransforms(CI); + return commonCastTransforms(CI); +} + +Instruction *InstCombiner::visitAddrSpaceCast(AddrSpaceCastInst &CI) { + return commonCastTransforms(CI); +} |