diff options
Diffstat (limited to 'llvm/lib/IR/ConstantFold.cpp')
| -rw-r--r-- | llvm/lib/IR/ConstantFold.cpp | 616 |
1 files changed, 77 insertions, 539 deletions
diff --git a/llvm/lib/IR/ConstantFold.cpp b/llvm/lib/IR/ConstantFold.cpp index 4c3325063c09..d499d74f7ba0 100644 --- a/llvm/lib/IR/ConstantFold.cpp +++ b/llvm/lib/IR/ConstantFold.cpp @@ -37,45 +37,6 @@ using namespace llvm::PatternMatch; // ConstantFold*Instruction Implementations //===----------------------------------------------------------------------===// -/// Convert the specified vector Constant node to the specified vector type. -/// At this point, we know that the elements of the input vector constant are -/// all simple integer or FP values. -static Constant *BitCastConstantVector(Constant *CV, VectorType *DstTy) { - - if (CV->isAllOnesValue()) return Constant::getAllOnesValue(DstTy); - if (CV->isNullValue()) return Constant::getNullValue(DstTy); - - // Do not iterate on scalable vector. The num of elements is unknown at - // compile-time. - if (isa<ScalableVectorType>(DstTy)) - return nullptr; - - // If this cast changes element count then we can't handle it here: - // doing so requires endianness information. This should be handled by - // Analysis/ConstantFolding.cpp - unsigned NumElts = cast<FixedVectorType>(DstTy)->getNumElements(); - if (NumElts != cast<FixedVectorType>(CV->getType())->getNumElements()) - return nullptr; - - Type *DstEltTy = DstTy->getElementType(); - // Fast path for splatted constants. - if (Constant *Splat = CV->getSplatValue()) { - return ConstantVector::getSplat(DstTy->getElementCount(), - ConstantExpr::getBitCast(Splat, DstEltTy)); - } - - SmallVector<Constant*, 16> Result; - Type *Ty = IntegerType::get(CV->getContext(), 32); - for (unsigned i = 0; i != NumElts; ++i) { - Constant *C = - ConstantExpr::getExtractElement(CV, ConstantInt::get(Ty, i)); - C = ConstantExpr::getBitCast(C, DstEltTy); - Result.push_back(C); - } - - return ConstantVector::get(Result); -} - /// This function determines which opcode to use to fold two constant cast /// expressions together. It uses CastInst::isEliminableCastPair to determine /// the opcode. Consequently its just a wrapper around that function. @@ -114,38 +75,19 @@ static Constant *FoldBitCast(Constant *V, Type *DestTy) { // Handle casts from one vector constant to another. We know that the src // and dest type have the same size (otherwise its an illegal cast). if (VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) { - if (VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) { - assert(DestPTy->getPrimitiveSizeInBits() == - SrcTy->getPrimitiveSizeInBits() && - "Not cast between same sized vectors!"); - SrcTy = nullptr; - // First, check for null. Undef is already handled. - if (isa<ConstantAggregateZero>(V)) - return Constant::getNullValue(DestTy); - - // Handle ConstantVector and ConstantAggregateVector. - return BitCastConstantVector(V, DestPTy); - } + if (V->isAllOnesValue()) + return Constant::getAllOnesValue(DestTy); // Canonicalize scalar-to-vector bitcasts into vector-to-vector bitcasts // This allows for other simplifications (although some of them // can only be handled by Analysis/ConstantFolding.cpp). if (isa<ConstantInt>(V) || isa<ConstantFP>(V)) return ConstantExpr::getBitCast(ConstantVector::get(V), DestPTy); + return nullptr; } - // Finally, implement bitcast folding now. The code below doesn't handle - // bitcast right. - if (isa<ConstantPointerNull>(V)) // ptr->ptr cast. - return ConstantPointerNull::get(cast<PointerType>(DestTy)); - // Handle integral constant input. if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { - if (DestTy->isIntegerTy()) - // Integral -> Integral. This is a no-op because the bit widths must - // be the same. Consequently, we just fold to V. - return V; - // See note below regarding the PPC_FP128 restriction. if (DestTy->isFloatingPointTy() && !DestTy->isPPC_FP128Ty()) return ConstantFP::get(DestTy->getContext(), @@ -192,7 +134,7 @@ static Constant *ExtractConstantBytes(Constant *C, unsigned ByteStart, assert(C->getType()->isIntegerTy() && (cast<IntegerType>(C->getType())->getBitWidth() & 7) == 0 && "Non-byte sized integer input"); - unsigned CSize = cast<IntegerType>(C->getType())->getBitWidth()/8; + [[maybe_unused]] unsigned CSize = cast<IntegerType>(C->getType())->getBitWidth()/8; assert(ByteSize && "Must be accessing some piece"); assert(ByteStart+ByteSize <= CSize && "Extracting invalid piece from input"); assert(ByteSize != CSize && "Should not extract everything"); @@ -213,58 +155,6 @@ static Constant *ExtractConstantBytes(Constant *C, unsigned ByteStart, switch (CE->getOpcode()) { default: return nullptr; - case Instruction::Or: { - Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize); - if (!RHS) - return nullptr; - - // X | -1 -> -1. - if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) - if (RHSC->isMinusOne()) - return RHSC; - - Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize); - if (!LHS) - return nullptr; - return ConstantExpr::getOr(LHS, RHS); - } - case Instruction::And: { - Constant *RHS = ExtractConstantBytes(CE->getOperand(1), ByteStart,ByteSize); - if (!RHS) - return nullptr; - - // X & 0 -> 0. - if (RHS->isNullValue()) - return RHS; - - Constant *LHS = ExtractConstantBytes(CE->getOperand(0), ByteStart,ByteSize); - if (!LHS) - return nullptr; - return ConstantExpr::getAnd(LHS, RHS); - } - case Instruction::LShr: { - ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1)); - if (!Amt) - return nullptr; - APInt ShAmt = Amt->getValue(); - // Cannot analyze non-byte shifts. - if ((ShAmt & 7) != 0) - return nullptr; - ShAmt.lshrInPlace(3); - - // If the extract is known to be all zeros, return zero. - if (ShAmt.uge(CSize - ByteStart)) - return Constant::getNullValue( - IntegerType::get(CE->getContext(), ByteSize * 8)); - // If the extract is known to be fully in the input, extract it. - if (ShAmt.ule(CSize - (ByteStart + ByteSize))) - return ExtractConstantBytes(CE->getOperand(0), - ByteStart + ShAmt.getZExtValue(), ByteSize); - - // TODO: Handle the 'partially zero' case. - return nullptr; - } - case Instruction::Shl: { ConstantInt *Amt = dyn_cast<ConstantInt>(CE->getOperand(1)); if (!Amt) @@ -287,43 +177,16 @@ static Constant *ExtractConstantBytes(Constant *C, unsigned ByteStart, // TODO: Handle the 'partially zero' case. return nullptr; } - - case Instruction::ZExt: { - unsigned SrcBitSize = - cast<IntegerType>(CE->getOperand(0)->getType())->getBitWidth(); - - // If extracting something that is completely zero, return 0. - if (ByteStart*8 >= SrcBitSize) - return Constant::getNullValue(IntegerType::get(CE->getContext(), - ByteSize*8)); - - // If exactly extracting the input, return it. - if (ByteStart == 0 && ByteSize*8 == SrcBitSize) - return CE->getOperand(0); - - // If extracting something completely in the input, if the input is a - // multiple of 8 bits, recurse. - if ((SrcBitSize&7) == 0 && (ByteStart+ByteSize)*8 <= SrcBitSize) - return ExtractConstantBytes(CE->getOperand(0), ByteStart, ByteSize); - - // Otherwise, if extracting a subset of the input, which is not multiple of - // 8 bits, do a shift and trunc to get the bits. - if ((ByteStart+ByteSize)*8 < SrcBitSize) { - assert((SrcBitSize&7) && "Shouldn't get byte sized case here"); - Constant *Res = CE->getOperand(0); - if (ByteStart) - Res = ConstantExpr::getLShr(Res, - ConstantInt::get(Res->getType(), ByteStart*8)); - return ConstantExpr::getTrunc(Res, IntegerType::get(C->getContext(), - ByteSize*8)); - } - - // TODO: Handle the 'partially zero' case. - return nullptr; - } } } +static Constant *foldMaybeUndesirableCast(unsigned opc, Constant *V, + Type *DestTy) { + return ConstantExpr::isDesirableCastOp(opc) + ? ConstantExpr::getCast(opc, V, DestTy) + : ConstantFoldCastInstruction(opc, V, DestTy); +} + Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V, Type *DestTy) { if (isa<PoisonValue>(V)) @@ -349,29 +212,7 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V, if (CE->isCast()) { // Try hard to fold cast of cast because they are often eliminable. if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy)) - return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy); - } else if (CE->getOpcode() == Instruction::GetElementPtr && - // Do not fold addrspacecast (gep 0, .., 0). It might make the - // addrspacecast uncanonicalized. - opc != Instruction::AddrSpaceCast && - // Do not fold bitcast (gep) with inrange index, as this loses - // information. - !cast<GEPOperator>(CE)->getInRangeIndex() && - // Do not fold if the gep type is a vector, as bitcasting - // operand 0 of a vector gep will result in a bitcast between - // different sizes. - !CE->getType()->isVectorTy()) { - // If all of the indexes in the GEP are null values, there is no pointer - // adjustment going on. We might as well cast the source pointer. - bool isAllNull = true; - for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i) - if (!CE->getOperand(i)->isNullValue()) { - isAllNull = false; - break; - } - if (isAllNull) - // This is casting one pointer type to another, always BitCast - return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy); + return foldMaybeUndesirableCast(newOpc, CE->getOperand(0), DestTy); } } @@ -386,18 +227,22 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V, Type *DstEltTy = DestVecTy->getElementType(); // Fast path for splatted constants. if (Constant *Splat = V->getSplatValue()) { + Constant *Res = foldMaybeUndesirableCast(opc, Splat, DstEltTy); + if (!Res) + return nullptr; return ConstantVector::getSplat( - cast<VectorType>(DestTy)->getElementCount(), - ConstantExpr::getCast(opc, Splat, DstEltTy)); + cast<VectorType>(DestTy)->getElementCount(), Res); } SmallVector<Constant *, 16> res; Type *Ty = IntegerType::get(V->getContext(), 32); for (unsigned i = 0, e = cast<FixedVectorType>(V->getType())->getNumElements(); i != e; ++i) { - Constant *C = - ConstantExpr::getExtractElement(V, ConstantInt::get(Ty, i)); - res.push_back(ConstantExpr::getCast(opc, C, DstEltTy)); + Constant *C = ConstantExpr::getExtractElement(V, ConstantInt::get(Ty, i)); + Constant *Casted = foldMaybeUndesirableCast(opc, C, DstEltTy); + if (!Casted) + return nullptr; + res.push_back(Casted); } return ConstantVector::get(res); } @@ -433,16 +278,6 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V, return ConstantInt::get(FPC->getContext(), IntVal); } return nullptr; // Can't fold. - case Instruction::IntToPtr: //always treated as unsigned - if (V->isNullValue()) // Is it an integral null value? - return ConstantPointerNull::get(cast<PointerType>(DestTy)); - return nullptr; // Other pointer types cannot be casted - case Instruction::PtrToInt: // always treated as unsigned - // Is it a null pointer value? - if (V->isNullValue()) - return ConstantInt::get(DestTy, 0); - // Other pointer types cannot be casted - return nullptr; case Instruction::UIToFP: case Instruction::SIToFP: if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { @@ -491,6 +326,8 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V, case Instruction::BitCast: return FoldBitCast(V, DestTy); case Instruction::AddrSpaceCast: + case Instruction::IntToPtr: + case Instruction::PtrToInt: return nullptr; } } @@ -1004,16 +841,6 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, Constant *C1, return C1; // X & -1 == X if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { - // (zext i32 to i64) & 4294967295 -> (zext i32 to i64) - if (CE1->getOpcode() == Instruction::ZExt) { - unsigned DstWidth = CI2->getType()->getBitWidth(); - unsigned SrcWidth = - CE1->getOperand(0)->getType()->getPrimitiveSizeInBits(); - APInt PossiblySetBits(APInt::getLowBitsSet(DstWidth, SrcWidth)); - if ((PossiblySetBits & CI2->getValue()) == PossiblySetBits) - return C1; - } - // If and'ing the address of a global with a constant, fold it. if (CE1->getOpcode() == Instruction::PtrToInt && isa<GlobalValue>(CE1->getOperand(0))) { @@ -1074,17 +901,13 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, Constant *C1, } } break; - case Instruction::AShr: - // ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2 - if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) - if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero. - return ConstantExpr::getLShr(C1, C2); - break; } } else if (isa<ConstantInt>(C1)) { // If C1 is a ConstantInt and C2 is not, swap the operands. if (Instruction::isCommutative(Opcode)) - return ConstantExpr::get(Opcode, C2, C1); + return ConstantExpr::isDesirableBinOp(Opcode) + ? ConstantExpr::get(Opcode, C2, C1) + : ConstantFoldBinaryInstruction(Opcode, C2, C1); } if (ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) { @@ -1241,8 +1064,6 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, Constant *C1, case Instruction::Add: case Instruction::Sub: return ConstantExpr::getXor(C1, C2); - case Instruction::Mul: - return ConstantExpr::getAnd(C1, C2); case Instruction::Shl: case Instruction::LShr: case Instruction::AShr: @@ -1268,70 +1089,6 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, Constant *C1, return nullptr; } -/// This function determines if there is anything we can decide about the two -/// constants provided. This doesn't need to handle simple things like -/// ConstantFP comparisons, but should instead handle ConstantExprs. -/// If we can determine that the two constants have a particular relation to -/// each other, we should return the corresponding FCmpInst predicate, -/// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in -/// ConstantFoldCompareInstruction. -/// -/// To simplify this code we canonicalize the relation so that the first -/// operand is always the most "complex" of the two. We consider ConstantFP -/// to be the simplest, and ConstantExprs to be the most complex. -static FCmpInst::Predicate evaluateFCmpRelation(Constant *V1, Constant *V2) { - assert(V1->getType() == V2->getType() && - "Cannot compare values of different types!"); - - // We do not know if a constant expression will evaluate to a number or NaN. - // Therefore, we can only say that the relation is unordered or equal. - if (V1 == V2) return FCmpInst::FCMP_UEQ; - - if (!isa<ConstantExpr>(V1)) { - if (!isa<ConstantExpr>(V2)) { - // Simple case, use the standard constant folder. - ConstantInt *R = nullptr; - R = dyn_cast<ConstantInt>( - ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, V1, V2)); - if (R && !R->isZero()) - return FCmpInst::FCMP_OEQ; - R = dyn_cast<ConstantInt>( - ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, V1, V2)); - if (R && !R->isZero()) - return FCmpInst::FCMP_OLT; - R = dyn_cast<ConstantInt>( - ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, V1, V2)); - if (R && !R->isZero()) - return FCmpInst::FCMP_OGT; - - // Nothing more we can do - return FCmpInst::BAD_FCMP_PREDICATE; - } - - // If the first operand is simple and second is ConstantExpr, swap operands. - FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1); - if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE) - return FCmpInst::getSwappedPredicate(SwappedRelation); - } else { - // Ok, the LHS is known to be a constantexpr. The RHS can be any of a - // constantexpr or a simple constant. - ConstantExpr *CE1 = cast<ConstantExpr>(V1); - switch (CE1->getOpcode()) { - case Instruction::FPTrunc: - case Instruction::FPExt: - case Instruction::UIToFP: - case Instruction::SIToFP: - // We might be able to do something with these but we don't right now. - break; - default: - break; - } - } - // There are MANY other foldings that we could perform here. They will - // probably be added on demand, as they seem needed. - return FCmpInst::BAD_FCMP_PREDICATE; -} - static ICmpInst::Predicate areGlobalsPotentiallyEqual(const GlobalValue *GV1, const GlobalValue *GV2) { auto isGlobalUnsafeForEquality = [](const GlobalValue *GV) { @@ -1362,66 +1119,54 @@ static ICmpInst::Predicate areGlobalsPotentiallyEqual(const GlobalValue *GV1, /// If we can determine that the two constants have a particular relation to /// each other, we should return the corresponding ICmp predicate, otherwise /// return ICmpInst::BAD_ICMP_PREDICATE. -/// -/// To simplify this code we canonicalize the relation so that the first -/// operand is always the most "complex" of the two. We consider simple -/// constants (like ConstantInt) to be the simplest, followed by -/// GlobalValues, followed by ConstantExpr's (the most complex). -/// -static ICmpInst::Predicate evaluateICmpRelation(Constant *V1, Constant *V2, - bool isSigned) { +static ICmpInst::Predicate evaluateICmpRelation(Constant *V1, Constant *V2) { assert(V1->getType() == V2->getType() && "Cannot compare different types of values!"); if (V1 == V2) return ICmpInst::ICMP_EQ; - if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1) && - !isa<BlockAddress>(V1)) { - if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2) && - !isa<BlockAddress>(V2)) { - // We distilled this down to a simple case, use the standard constant - // folder. - ConstantInt *R = nullptr; - ICmpInst::Predicate pred = ICmpInst::ICMP_EQ; - R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); - if (R && !R->isZero()) - return pred; - pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; - R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); - if (R && !R->isZero()) - return pred; - pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; - R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, V1, V2)); - if (R && !R->isZero()) - return pred; + // The following folds only apply to pointers. + if (!V1->getType()->isPointerTy()) + return ICmpInst::BAD_ICMP_PREDICATE; - // If we couldn't figure it out, bail. - return ICmpInst::BAD_ICMP_PREDICATE; - } - - // If the first operand is simple, swap operands. - ICmpInst::Predicate SwappedRelation = - evaluateICmpRelation(V2, V1, isSigned); + // To simplify this code we canonicalize the relation so that the first + // operand is always the most "complex" of the two. We consider simple + // constants (like ConstantPointerNull) to be the simplest, followed by + // BlockAddress, GlobalValues, and ConstantExpr's (the most complex). + auto GetComplexity = [](Constant *V) { + if (isa<ConstantExpr>(V)) + return 3; + if (isa<GlobalValue>(V)) + return 2; + if (isa<BlockAddress>(V)) + return 1; + return 0; + }; + if (GetComplexity(V1) < GetComplexity(V2)) { + ICmpInst::Predicate SwappedRelation = evaluateICmpRelation(V2, V1); if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) return ICmpInst::getSwappedPredicate(SwappedRelation); + return ICmpInst::BAD_ICMP_PREDICATE; + } - } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(V1)) { - if (isa<ConstantExpr>(V2)) { // Swap as necessary. - ICmpInst::Predicate SwappedRelation = - evaluateICmpRelation(V2, V1, isSigned); - if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) - return ICmpInst::getSwappedPredicate(SwappedRelation); - return ICmpInst::BAD_ICMP_PREDICATE; + if (const BlockAddress *BA = dyn_cast<BlockAddress>(V1)) { + // Now we know that the RHS is a BlockAddress or simple constant. + if (const BlockAddress *BA2 = dyn_cast<BlockAddress>(V2)) { + // Block address in another function can't equal this one, but block + // addresses in the current function might be the same if blocks are + // empty. + if (BA2->getFunction() != BA->getFunction()) + return ICmpInst::ICMP_NE; + } else if (isa<ConstantPointerNull>(V2)) { + return ICmpInst::ICMP_NE; } - + } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(V1)) { // Now we know that the RHS is a GlobalValue, BlockAddress or simple - // constant (which, since the types must match, means that it's a - // ConstantPointerNull). + // constant. if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) { return areGlobalsPotentiallyEqual(GV, GV2); } else if (isa<BlockAddress>(V2)) { return ICmpInst::ICMP_NE; // Globals never equal labels. - } else { - assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!"); + } else if (isa<ConstantPointerNull>(V2)) { // GlobalVals can never be null unless they have external weak linkage. // We don't try to evaluate aliases here. // NOTE: We should not be doing this constant folding if null pointer @@ -1432,30 +1177,6 @@ static ICmpInst::Predicate evaluateICmpRelation(Constant *V1, Constant *V2, GV->getType()->getAddressSpace())) return ICmpInst::ICMP_UGT; } - } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(V1)) { - if (isa<ConstantExpr>(V2)) { // Swap as necessary. - ICmpInst::Predicate SwappedRelation = - evaluateICmpRelation(V2, V1, isSigned); - if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE) - return ICmpInst::getSwappedPredicate(SwappedRelation); - return ICmpInst::BAD_ICMP_PREDICATE; - } - - // Now we know that the RHS is a GlobalValue, BlockAddress or simple - // constant (which, since the types must match, means that it is a - // ConstantPointerNull). - if (const BlockAddress *BA2 = dyn_cast<BlockAddress>(V2)) { - // Block address in another function can't equal this one, but block - // addresses in the current function might be the same if blocks are - // empty. - if (BA2->getFunction() != BA->getFunction()) - return ICmpInst::ICMP_NE; - } else { - // Block addresses aren't null, don't equal the address of globals. - assert((isa<ConstantPointerNull>(V2) || isa<GlobalValue>(V2)) && - "Canonicalization guarantee!"); - return ICmpInst::ICMP_NE; - } } else { // Ok, the LHS is known to be a constantexpr. The RHS can be any of a // constantexpr, a global, block address, or a simple constant. @@ -1463,39 +1184,6 @@ static ICmpInst::Predicate evaluateICmpRelation(Constant *V1, Constant *V2, Constant *CE1Op0 = CE1->getOperand(0); switch (CE1->getOpcode()) { - case Instruction::Trunc: - case Instruction::FPTrunc: - case Instruction::FPExt: - case Instruction::FPToUI: - case Instruction::FPToSI: - break; // We can't evaluate floating point casts or truncations. - - case Instruction::BitCast: - // If this is a global value cast, check to see if the RHS is also a - // GlobalValue. - if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) - if (const GlobalValue *GV2 = dyn_cast<GlobalValue>(V2)) - return areGlobalsPotentiallyEqual(GV, GV2); - [[fallthrough]]; - case Instruction::UIToFP: - case Instruction::SIToFP: - case Instruction::ZExt: - case Instruction::SExt: - // We can't evaluate floating point casts or truncations. - if (CE1Op0->getType()->isFPOrFPVectorTy()) - break; - - // If the cast is not actually changing bits, and the second operand is a - // null pointer, do the comparison with the pre-casted value. - if (V2->isNullValue() && CE1->getType()->isIntOrPtrTy()) { - if (CE1->getOpcode() == Instruction::ZExt) isSigned = false; - if (CE1->getOpcode() == Instruction::SExt) isSigned = true; - return evaluateICmpRelation(CE1Op0, - Constant::getNullValue(CE1Op0->getType()), - isSigned); - } - break; - case Instruction::GetElementPtr: { GEPOperator *CE1GEP = cast<GEPOperator>(CE1); // Ok, since this is a getelementptr, we know that the constant has a @@ -1541,25 +1229,6 @@ static ICmpInst::Predicate evaluateICmpRelation(Constant *V1, Constant *V2, return ICmpInst::BAD_ICMP_PREDICATE; } -static Constant *constantFoldCompareGlobalToNull(CmpInst::Predicate Predicate, - Constant *C1, Constant *C2) { - const GlobalValue *GV = dyn_cast<GlobalValue>(C2); - if (!GV || !C1->isNullValue()) - return nullptr; - - // Don't try to evaluate aliases. External weak GV can be null. - if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage() && - !NullPointerIsDefined(nullptr /* F */, - GV->getType()->getAddressSpace())) { - if (Predicate == ICmpInst::ICMP_EQ) - return ConstantInt::getFalse(C1->getContext()); - else if (Predicate == ICmpInst::ICMP_NE) - return ConstantInt::getTrue(C1->getContext()); - } - - return nullptr; -} - Constant *llvm::ConstantFoldCompareInstruction(CmpInst::Predicate Predicate, Constant *C1, Constant *C2) { Type *ResultTy; @@ -1598,14 +1267,6 @@ Constant *llvm::ConstantFoldCompareInstruction(CmpInst::Predicate Predicate, return ConstantInt::get(ResultTy, CmpInst::isUnordered(Predicate)); } - // icmp eq/ne(null,GV) -> false/true - if (Constant *Folded = constantFoldCompareGlobalToNull(Predicate, C1, C2)) - return Folded; - - // icmp eq/ne(GV,null) -> false/true - if (Constant *Folded = constantFoldCompareGlobalToNull(Predicate, C2, C1)) - return Folded; - if (C2->isNullValue()) { // The caller is expected to commute the operands if the constant expression // is C2. @@ -1671,83 +1332,18 @@ Constant *llvm::ConstantFoldCompareInstruction(CmpInst::Predicate Predicate, return ConstantVector::get(ResElts); } - if (C1->getType()->isFloatingPointTy() && - // Only call evaluateFCmpRelation if we have a constant expr to avoid - // infinite recursive loop - (isa<ConstantExpr>(C1) || isa<ConstantExpr>(C2))) { - int Result = -1; // -1 = unknown, 0 = known false, 1 = known true. - switch (evaluateFCmpRelation(C1, C2)) { - default: llvm_unreachable("Unknown relation!"); - case FCmpInst::FCMP_UNO: - case FCmpInst::FCMP_ORD: - case FCmpInst::FCMP_UNE: - case FCmpInst::FCMP_ULT: - case FCmpInst::FCMP_UGT: - case FCmpInst::FCMP_ULE: - case FCmpInst::FCMP_UGE: - case FCmpInst::FCMP_TRUE: - case FCmpInst::FCMP_FALSE: - case FCmpInst::BAD_FCMP_PREDICATE: - break; // Couldn't determine anything about these constants. - case FCmpInst::FCMP_OEQ: // We know that C1 == C2 - Result = - (Predicate == FCmpInst::FCMP_UEQ || Predicate == FCmpInst::FCMP_OEQ || - Predicate == FCmpInst::FCMP_ULE || Predicate == FCmpInst::FCMP_OLE || - Predicate == FCmpInst::FCMP_UGE || Predicate == FCmpInst::FCMP_OGE); - break; - case FCmpInst::FCMP_OLT: // We know that C1 < C2 - Result = - (Predicate == FCmpInst::FCMP_UNE || Predicate == FCmpInst::FCMP_ONE || - Predicate == FCmpInst::FCMP_ULT || Predicate == FCmpInst::FCMP_OLT || - Predicate == FCmpInst::FCMP_ULE || Predicate == FCmpInst::FCMP_OLE); - break; - case FCmpInst::FCMP_OGT: // We know that C1 > C2 - Result = - (Predicate == FCmpInst::FCMP_UNE || Predicate == FCmpInst::FCMP_ONE || - Predicate == FCmpInst::FCMP_UGT || Predicate == FCmpInst::FCMP_OGT || - Predicate == FCmpInst::FCMP_UGE || Predicate == FCmpInst::FCMP_OGE); - break; - case FCmpInst::FCMP_OLE: // We know that C1 <= C2 - // We can only partially decide this relation. - if (Predicate == FCmpInst::FCMP_UGT || Predicate == FCmpInst::FCMP_OGT) - Result = 0; - else if (Predicate == FCmpInst::FCMP_ULT || - Predicate == FCmpInst::FCMP_OLT) - Result = 1; - break; - case FCmpInst::FCMP_OGE: // We known that C1 >= C2 - // We can only partially decide this relation. - if (Predicate == FCmpInst::FCMP_ULT || Predicate == FCmpInst::FCMP_OLT) - Result = 0; - else if (Predicate == FCmpInst::FCMP_UGT || - Predicate == FCmpInst::FCMP_OGT) - Result = 1; - break; - case FCmpInst::FCMP_ONE: // We know that C1 != C2 - // We can only partially decide this relation. - if (Predicate == FCmpInst::FCMP_OEQ || Predicate == FCmpInst::FCMP_UEQ) - Result = 0; - else if (Predicate == FCmpInst::FCMP_ONE || - Predicate == FCmpInst::FCMP_UNE) - Result = 1; - break; - case FCmpInst::FCMP_UEQ: // We know that C1 == C2 || isUnordered(C1, C2). - // We can only partially decide this relation. + if (C1->getType()->isFPOrFPVectorTy()) { + if (C1 == C2) { + // We know that C1 == C2 || isUnordered(C1, C2). if (Predicate == FCmpInst::FCMP_ONE) - Result = 0; + return ConstantInt::getFalse(ResultTy); else if (Predicate == FCmpInst::FCMP_UEQ) - Result = 1; - break; + return ConstantInt::getTrue(ResultTy); } - - // If we evaluated the result, return it now. - if (Result != -1) - return ConstantInt::get(ResultTy, Result); - } else { // Evaluate the relation between the two constants, per the predicate. int Result = -1; // -1 = unknown, 0 = known false, 1 = known true. - switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(Predicate))) { + switch (evaluateICmpRelation(C1, C2)) { default: llvm_unreachable("Unknown relational!"); case ICmpInst::BAD_ICMP_PREDICATE: break; // Couldn't determine anything about these constants. @@ -1832,38 +1428,6 @@ Constant *llvm::ConstantFoldCompareInstruction(CmpInst::Predicate Predicate, if (Result != -1) return ConstantInt::get(ResultTy, Result); - // If the right hand side is a bitcast, try using its inverse to simplify - // it by moving it to the left hand side. We can't do this if it would turn - // a vector compare into a scalar compare or visa versa, or if it would turn - // the operands into FP values. - if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(C2)) { - Constant *CE2Op0 = CE2->getOperand(0); - if (CE2->getOpcode() == Instruction::BitCast && - CE2->getType()->isVectorTy() == CE2Op0->getType()->isVectorTy() && - !CE2Op0->getType()->isFPOrFPVectorTy()) { - Constant *Inverse = ConstantExpr::getBitCast(C1, CE2Op0->getType()); - return ConstantExpr::getICmp(Predicate, Inverse, CE2Op0); - } - } - - // If the left hand side is an extension, try eliminating it. - if (ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) { - if ((CE1->getOpcode() == Instruction::SExt && - ICmpInst::isSigned(Predicate)) || - (CE1->getOpcode() == Instruction::ZExt && - !ICmpInst::isSigned(Predicate))) { - Constant *CE1Op0 = CE1->getOperand(0); - Constant *CE1Inverse = ConstantExpr::getTrunc(CE1, CE1Op0->getType()); - if (CE1Inverse == CE1Op0) { - // Check whether we can safely truncate the right hand side. - Constant *C2Inverse = ConstantExpr::getTrunc(C2, CE1Op0->getType()); - if (ConstantExpr::getCast(CE1->getOpcode(), C2Inverse, - C2->getType()) == C2) - return ConstantExpr::getICmp(Predicate, CE1Inverse, C2Inverse); - } - } - } - if ((!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) || (C1->isNullValue() && !C2->isNullValue())) { // If C2 is a constant expr and C1 isn't, flip them around and fold the @@ -1974,8 +1538,13 @@ static Constant *foldGEPOfGEP(GEPOperator *GEP, Type *PointeeTy, bool InBounds, Type *CommonTy = Type::getIntNTy(LastIdxTy->getContext(), CommonExtendedWidth); - Idx0 = ConstantExpr::getSExtOrBitCast(Idx0, CommonTy); - LastIdx = ConstantExpr::getSExtOrBitCast(LastIdx, CommonTy); + if (Idx0->getType() != CommonTy) + Idx0 = ConstantFoldCastInstruction(Instruction::SExt, Idx0, CommonTy); + if (LastIdx->getType() != CommonTy) + LastIdx = + ConstantFoldCastInstruction(Instruction::SExt, LastIdx, CommonTy); + if (!Idx0 || !LastIdx) + return nullptr; } NewIndices.push_back(ConstantExpr::get(Instruction::Add, Idx0, LastIdx)); @@ -2025,39 +1594,6 @@ Constant *llvm::ConstantFoldGetElementPtr(Type *PointeeTy, Constant *C, cast<VectorType>(GEPTy)->getElementCount(), C) : C; - if (C->isNullValue()) { - bool isNull = true; - for (Value *Idx : Idxs) - if (!isa<UndefValue>(Idx) && !cast<Constant>(Idx)->isNullValue()) { - isNull = false; - break; - } - if (isNull) { - PointerType *PtrTy = cast<PointerType>(C->getType()->getScalarType()); - Type *Ty = GetElementPtrInst::getIndexedType(PointeeTy, Idxs); - - assert(Ty && "Invalid indices for GEP!"); - Type *OrigGEPTy = PointerType::get(Ty, PtrTy->getAddressSpace()); - Type *GEPTy = PointerType::get(Ty, PtrTy->getAddressSpace()); - if (VectorType *VT = dyn_cast<VectorType>(C->getType())) - GEPTy = VectorType::get(OrigGEPTy, VT->getElementCount()); - - // The GEP returns a vector of pointers when one of more of - // its arguments is a vector. - for (Value *Idx : Idxs) { - if (auto *VT = dyn_cast<VectorType>(Idx->getType())) { - assert((!isa<VectorType>(GEPTy) || isa<ScalableVectorType>(GEPTy) == - isa<ScalableVectorType>(VT)) && - "Mismatched GEPTy vector types"); - GEPTy = VectorType::get(OrigGEPTy, VT->getElementCount()); - break; - } - } - - return Constant::getNullValue(GEPTy); - } - } - if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) if (auto *GEP = dyn_cast<GEPOperator>(CE)) if (Constant *C = foldGEPOfGEP(GEP, PointeeTy, InBounds, Idxs)) @@ -2193,11 +1729,13 @@ Constant *llvm::ConstantFoldGetElementPtr(Type *PointeeTy, Constant *C, : cast<FixedVectorType>(CurrIdx->getType())->getNumElements()); if (!PrevIdx->getType()->isIntOrIntVectorTy(CommonExtendedWidth)) - PrevIdx = ConstantExpr::getSExt(PrevIdx, ExtendedTy); + PrevIdx = + ConstantFoldCastInstruction(Instruction::SExt, PrevIdx, ExtendedTy); if (!Div->getType()->isIntOrIntVectorTy(CommonExtendedWidth)) - Div = ConstantExpr::getSExt(Div, ExtendedTy); + Div = ConstantFoldCastInstruction(Instruction::SExt, Div, ExtendedTy); + assert(PrevIdx && Div && "Should have folded"); NewIdxs[i - 1] = ConstantExpr::getAdd(PrevIdx, Div); } |