X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=lib%2FAnalysis%2FValueTracking.cpp;h=d3cc52d87e0dcbe3f90dd020cde5948a9ac5645e;hp=d245783ec6529b75095eef4e166f844ee50c8626;hb=a098c770e1f96f6f728cc220ae6f4f5297d0603d;hpb=b401e3bd16c3d648464606d5e5b496dd61d12afc diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp index d245783ec65..d3cc52d87e0 100644 --- a/lib/Analysis/ValueTracking.cpp +++ b/lib/Analysis/ValueTracking.cpp @@ -13,40 +13,160 @@ //===----------------------------------------------------------------------===// #include "llvm/Analysis/ValueTracking.h" +#include "llvm/Analysis/AssumptionTracker.h" +#include "llvm/ADT/SmallPtrSet.h" #include "llvm/Analysis/InstructionSimplify.h" -#include "llvm/Constants.h" -#include "llvm/Instructions.h" -#include "llvm/GlobalVariable.h" -#include "llvm/GlobalAlias.h" -#include "llvm/IntrinsicInst.h" -#include "llvm/LLVMContext.h" -#include "llvm/Metadata.h" -#include "llvm/Operator.h" -#include "llvm/Target/TargetData.h" -#include "llvm/Support/ConstantRange.h" -#include "llvm/Support/GetElementPtrTypeIterator.h" +#include "llvm/Analysis/MemoryBuiltins.h" +#include "llvm/IR/CallSite.h" +#include "llvm/IR/ConstantRange.h" +#include "llvm/IR/Constants.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/Dominators.h" +#include "llvm/IR/GetElementPtrTypeIterator.h" +#include "llvm/IR/GlobalAlias.h" +#include "llvm/IR/GlobalVariable.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/LLVMContext.h" +#include "llvm/IR/Metadata.h" +#include "llvm/IR/Operator.h" +#include "llvm/IR/PatternMatch.h" +#include "llvm/Support/Debug.h" #include "llvm/Support/MathExtras.h" -#include "llvm/Support/PatternMatch.h" -#include "llvm/ADT/SmallPtrSet.h" #include using namespace llvm; using namespace llvm::PatternMatch; const unsigned MaxDepth = 6; -/// getBitWidth - Returns the bitwidth of the given scalar or pointer type (if -/// unknown returns 0). For vector types, returns the element type's bitwidth. -static unsigned getBitWidth(Type *Ty, const TargetData *TD) { +/// Returns the bitwidth of the given scalar or pointer type (if unknown returns +/// 0). For vector types, returns the element type's bitwidth. +static unsigned getBitWidth(Type *Ty, const DataLayout *TD) { if (unsigned BitWidth = Ty->getScalarSizeInBits()) return BitWidth; - assert(isa(Ty) && "Expected a pointer type!"); - return TD ? TD->getPointerSizeInBits() : 0; + + return TD ? TD->getPointerTypeSizeInBits(Ty) : 0; +} + +// Many of these functions have internal versions that take an assumption +// exclusion set. This is because of the potential for mutual recursion to +// cause computeKnownBits to repeatedly visit the same assume intrinsic. The +// classic case of this is assume(x = y), which will attempt to determine +// bits in x from bits in y, which will attempt to determine bits in y from +// bits in x, etc. Regarding the mutual recursion, computeKnownBits can call +// isKnownNonZero, which calls computeKnownBits and ComputeSignBit and +// isKnownToBeAPowerOfTwo (all of which can call computeKnownBits), and so on. +typedef SmallPtrSet ExclInvsSet; + +namespace { +// Simplifying using an assume can only be done in a particular control-flow +// context (the context instruction provides that context). If an assume and +// the context instruction are not in the same block then the DT helps in +// figuring out if we can use it. +struct Query { + ExclInvsSet ExclInvs; + AssumptionTracker *AT; + const Instruction *CxtI; + const DominatorTree *DT; + + Query(AssumptionTracker *AT = nullptr, const Instruction *CxtI = nullptr, + const DominatorTree *DT = nullptr) + : AT(AT), CxtI(CxtI), DT(DT) {} + + Query(const Query &Q, const Value *NewExcl) + : ExclInvs(Q.ExclInvs), AT(Q.AT), CxtI(Q.CxtI), DT(Q.DT) { + ExclInvs.insert(NewExcl); + } +}; +} // end anonymous namespace + +// Given the provided Value and, potentially, a context instruction, return +// the preferred context instruction (if any). +static const Instruction *safeCxtI(const Value *V, const Instruction *CxtI) { + // If we've been provided with a context instruction, then use that (provided + // it has been inserted). + if (CxtI && CxtI->getParent()) + return CxtI; + + // If the value is really an already-inserted instruction, then use that. + CxtI = dyn_cast(V); + if (CxtI && CxtI->getParent()) + return CxtI; + + return nullptr; +} + +static void computeKnownBits(Value *V, APInt &KnownZero, APInt &KnownOne, + const DataLayout *TD, unsigned Depth, + const Query &Q); + +void llvm::computeKnownBits(Value *V, APInt &KnownZero, APInt &KnownOne, + const DataLayout *TD, unsigned Depth, + AssumptionTracker *AT, const Instruction *CxtI, + const DominatorTree *DT) { + ::computeKnownBits(V, KnownZero, KnownOne, TD, Depth, + Query(AT, safeCxtI(V, CxtI), DT)); +} + +static void ComputeSignBit(Value *V, bool &KnownZero, bool &KnownOne, + const DataLayout *TD, unsigned Depth, + const Query &Q); + +void llvm::ComputeSignBit(Value *V, bool &KnownZero, bool &KnownOne, + const DataLayout *TD, unsigned Depth, + AssumptionTracker *AT, const Instruction *CxtI, + const DominatorTree *DT) { + ::ComputeSignBit(V, KnownZero, KnownOne, TD, Depth, + Query(AT, safeCxtI(V, CxtI), DT)); } -static void ComputeMaskedBitsAddSub(bool Add, Value *Op0, Value *Op1, bool NSW, - APInt &KnownZero, APInt &KnownOne, - APInt &KnownZero2, APInt &KnownOne2, - const TargetData *TD, unsigned Depth) { +static bool isKnownToBeAPowerOfTwo(Value *V, bool OrZero, unsigned Depth, + const Query &Q); + +bool llvm::isKnownToBeAPowerOfTwo(Value *V, bool OrZero, unsigned Depth, + AssumptionTracker *AT, + const Instruction *CxtI, + const DominatorTree *DT) { + return ::isKnownToBeAPowerOfTwo(V, OrZero, Depth, + Query(AT, safeCxtI(V, CxtI), DT)); +} + +static bool isKnownNonZero(Value *V, const DataLayout *TD, unsigned Depth, + const Query &Q); + +bool llvm::isKnownNonZero(Value *V, const DataLayout *TD, unsigned Depth, + AssumptionTracker *AT, const Instruction *CxtI, + const DominatorTree *DT) { + return ::isKnownNonZero(V, TD, Depth, Query(AT, safeCxtI(V, CxtI), DT)); +} + +static bool MaskedValueIsZero(Value *V, const APInt &Mask, + const DataLayout *TD, unsigned Depth, + const Query &Q); + +bool llvm::MaskedValueIsZero(Value *V, const APInt &Mask, + const DataLayout *TD, unsigned Depth, + AssumptionTracker *AT, const Instruction *CxtI, + const DominatorTree *DT) { + return ::MaskedValueIsZero(V, Mask, TD, Depth, + Query(AT, safeCxtI(V, CxtI), DT)); +} + +static unsigned ComputeNumSignBits(Value *V, const DataLayout *TD, + unsigned Depth, const Query &Q); + +unsigned llvm::ComputeNumSignBits(Value *V, const DataLayout *TD, + unsigned Depth, AssumptionTracker *AT, + const Instruction *CxtI, + const DominatorTree *DT) { + return ::ComputeNumSignBits(V, TD, Depth, Query(AT, safeCxtI(V, CxtI), DT)); +} + +static void computeKnownBitsAddSub(bool Add, Value *Op0, Value *Op1, bool NSW, + APInt &KnownZero, APInt &KnownOne, + APInt &KnownZero2, APInt &KnownOne2, + const DataLayout *TD, unsigned Depth, + const Query &Q) { if (!Add) { if (ConstantInt *CLHS = dyn_cast(Op0)) { // We know that the top bits of C-X are clear if X contains less bits @@ -57,8 +177,8 @@ static void ComputeMaskedBitsAddSub(bool Add, Value *Op0, Value *Op1, bool NSW, unsigned NLZ = (CLHS->getValue()+1).countLeadingZeros(); // NLZ can't be BitWidth with no sign bit APInt MaskV = APInt::getHighBitsSet(BitWidth, NLZ+1); - llvm::ComputeMaskedBits(Op1, KnownZero2, KnownOne2, TD, Depth+1); - + computeKnownBits(Op1, KnownZero2, KnownOne2, TD, Depth+1, Q); + // If all of the MaskV bits are known to be zero, then we know the // output top bits are zero, because we now know that the output is // from [0-C]. @@ -73,71 +193,63 @@ static void ComputeMaskedBitsAddSub(bool Add, Value *Op0, Value *Op1, bool NSW, unsigned BitWidth = KnownZero.getBitWidth(); - // If one of the operands has trailing zeros, then the bits that the - // other operand has in those bit positions will be preserved in the - // result. For an add, this works with either operand. For a subtract, - // this only works if the known zeros are in the right operand. + // If an initial sequence of bits in the result is not needed, the + // corresponding bits in the operands are not needed. APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0); - llvm::ComputeMaskedBits(Op0, LHSKnownZero, LHSKnownOne, TD, Depth+1); - assert((LHSKnownZero & LHSKnownOne) == 0 && - "Bits known to be one AND zero?"); - unsigned LHSKnownZeroOut = LHSKnownZero.countTrailingOnes(); - - llvm::ComputeMaskedBits(Op1, KnownZero2, KnownOne2, TD, Depth+1); - assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); - unsigned RHSKnownZeroOut = KnownZero2.countTrailingOnes(); - - // Determine which operand has more trailing zeros, and use that - // many bits from the other operand. - if (LHSKnownZeroOut > RHSKnownZeroOut) { - if (Add) { - APInt Mask = APInt::getLowBitsSet(BitWidth, LHSKnownZeroOut); - KnownZero |= KnownZero2 & Mask; - KnownOne |= KnownOne2 & Mask; - } else { - // If the known zeros are in the left operand for a subtract, - // fall back to the minimum known zeros in both operands. - KnownZero |= APInt::getLowBitsSet(BitWidth, - std::min(LHSKnownZeroOut, - RHSKnownZeroOut)); - } - } else if (RHSKnownZeroOut >= LHSKnownZeroOut) { - APInt Mask = APInt::getLowBitsSet(BitWidth, RHSKnownZeroOut); - KnownZero |= LHSKnownZero & Mask; - KnownOne |= LHSKnownOne & Mask; + computeKnownBits(Op0, LHSKnownZero, LHSKnownOne, TD, Depth+1, Q); + computeKnownBits(Op1, KnownZero2, KnownOne2, TD, Depth+1, Q); + + // Carry in a 1 for a subtract, rather than a 0. + APInt CarryIn(BitWidth, 0); + if (!Add) { + // Sum = LHS + ~RHS + 1 + std::swap(KnownZero2, KnownOne2); + CarryIn.setBit(0); } + APInt PossibleSumZero = ~LHSKnownZero + ~KnownZero2 + CarryIn; + APInt PossibleSumOne = LHSKnownOne + KnownOne2 + CarryIn; + + // Compute known bits of the carry. + APInt CarryKnownZero = ~(PossibleSumZero ^ LHSKnownZero ^ KnownZero2); + APInt CarryKnownOne = PossibleSumOne ^ LHSKnownOne ^ KnownOne2; + + // Compute set of known bits (where all three relevant bits are known). + APInt LHSKnown = LHSKnownZero | LHSKnownOne; + APInt RHSKnown = KnownZero2 | KnownOne2; + APInt CarryKnown = CarryKnownZero | CarryKnownOne; + APInt Known = LHSKnown & RHSKnown & CarryKnown; + + assert((PossibleSumZero & Known) == (PossibleSumOne & Known) && + "known bits of sum differ"); + + // Compute known bits of the result. + KnownZero = ~PossibleSumOne & Known; + KnownOne = PossibleSumOne & Known; + // Are we still trying to solve for the sign bit? - if (!KnownZero.isNegative() && !KnownOne.isNegative()) { + if (!Known.isNegative()) { if (NSW) { - if (Add) { - // Adding two positive numbers can't wrap into negative - if (LHSKnownZero.isNegative() && KnownZero2.isNegative()) - KnownZero |= APInt::getSignBit(BitWidth); - // and adding two negative numbers can't wrap into positive. - else if (LHSKnownOne.isNegative() && KnownOne2.isNegative()) - KnownOne |= APInt::getSignBit(BitWidth); - } else { - // Subtracting a negative number from a positive one can't wrap - if (LHSKnownZero.isNegative() && KnownOne2.isNegative()) - KnownZero |= APInt::getSignBit(BitWidth); - // neither can subtracting a positive number from a negative one. - else if (LHSKnownOne.isNegative() && KnownZero2.isNegative()) - KnownOne |= APInt::getSignBit(BitWidth); - } + // Adding two non-negative numbers, or subtracting a negative number from + // a non-negative one, can't wrap into negative. + if (LHSKnownZero.isNegative() && KnownZero2.isNegative()) + KnownZero |= APInt::getSignBit(BitWidth); + // Adding two negative numbers, or subtracting a non-negative number from + // a negative one, can't wrap into non-negative. + else if (LHSKnownOne.isNegative() && KnownOne2.isNegative()) + KnownOne |= APInt::getSignBit(BitWidth); } } } -static void ComputeMaskedBitsMul(Value *Op0, Value *Op1, bool NSW, - APInt &KnownZero, APInt &KnownOne, - APInt &KnownZero2, APInt &KnownOne2, - const TargetData *TD, unsigned Depth) { +static void computeKnownBitsMul(Value *Op0, Value *Op1, bool NSW, + APInt &KnownZero, APInt &KnownOne, + APInt &KnownZero2, APInt &KnownOne2, + const DataLayout *TD, unsigned Depth, + const Query &Q) { unsigned BitWidth = KnownZero.getBitWidth(); - ComputeMaskedBits(Op1, KnownZero, KnownOne, TD, Depth+1); - ComputeMaskedBits(Op0, KnownZero2, KnownOne2, TD, Depth+1); - assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); - assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); + computeKnownBits(Op1, KnownZero, KnownOne, TD, Depth+1, Q); + computeKnownBits(Op0, KnownZero2, KnownOne2, TD, Depth+1, Q); bool isKnownNegative = false; bool isKnownNonNegative = false; @@ -158,9 +270,9 @@ static void ComputeMaskedBitsMul(Value *Op0, Value *Op1, bool NSW, // negative or zero. if (!isKnownNonNegative) isKnownNegative = (isKnownNegativeOp1 && isKnownNonNegativeOp0 && - isKnownNonZero(Op0, TD, Depth)) || + isKnownNonZero(Op0, TD, Depth, Q)) || (isKnownNegativeOp0 && isKnownNonNegativeOp1 && - isKnownNonZero(Op1, TD, Depth)); + isKnownNonZero(Op1, TD, Depth, Q)); } } @@ -191,7 +303,8 @@ static void ComputeMaskedBitsMul(Value *Op0, Value *Op1, bool NSW, KnownOne.setBit(BitWidth - 1); } -void llvm::computeMaskedBitsLoad(const MDNode &Ranges, APInt &KnownZero) { +void llvm::computeKnownBitsFromRangeMetadata(const MDNode &Ranges, + APInt &KnownZero) { unsigned BitWidth = KnownZero.getBitWidth(); unsigned NumRanges = Ranges.getNumOperands() / 2; assert(NumRanges >= 1); @@ -199,8 +312,10 @@ void llvm::computeMaskedBitsLoad(const MDNode &Ranges, APInt &KnownZero) { // Use the high end of the ranges to find leading zeros. unsigned MinLeadingZeros = BitWidth; for (unsigned i = 0; i < NumRanges; ++i) { - ConstantInt *Lower = cast(Ranges.getOperand(2*i + 0)); - ConstantInt *Upper = cast(Ranges.getOperand(2*i + 1)); + ConstantInt *Lower = + mdconst::extract(Ranges.getOperand(2 * i + 0)); + ConstantInt *Upper = + mdconst::extract(Ranges.getOperand(2 * i + 1)); ConstantRange Range(Lower->getValue(), Upper->getValue()); if (Range.isWrappedSet()) MinLeadingZeros = 0; // -1 has no zeros @@ -210,8 +325,414 @@ void llvm::computeMaskedBitsLoad(const MDNode &Ranges, APInt &KnownZero) { KnownZero = APInt::getHighBitsSet(BitWidth, MinLeadingZeros); } -/// ComputeMaskedBits - Determine which of the bits are known to be either zero -/// or one and return them in the KnownZero/KnownOne bit sets. + +static bool isEphemeralValueOf(Instruction *I, const Value *E) { + SmallVector WorkSet(1, I); + SmallPtrSet Visited; + SmallPtrSet EphValues; + + while (!WorkSet.empty()) { + const Value *V = WorkSet.pop_back_val(); + if (!Visited.insert(V).second) + continue; + + // If all uses of this value are ephemeral, then so is this value. + bool FoundNEUse = false; + for (const User *I : V->users()) + if (!EphValues.count(I)) { + FoundNEUse = true; + break; + } + + if (!FoundNEUse) { + if (V == E) + return true; + + EphValues.insert(V); + if (const User *U = dyn_cast(V)) + for (User::const_op_iterator J = U->op_begin(), JE = U->op_end(); + J != JE; ++J) { + if (isSafeToSpeculativelyExecute(*J)) + WorkSet.push_back(*J); + } + } + } + + return false; +} + +// Is this an intrinsic that cannot be speculated but also cannot trap? +static bool isAssumeLikeIntrinsic(const Instruction *I) { + if (const CallInst *CI = dyn_cast(I)) + if (Function *F = CI->getCalledFunction()) + switch (F->getIntrinsicID()) { + default: break; + // FIXME: This list is repeated from NoTTI::getIntrinsicCost. + case Intrinsic::assume: + case Intrinsic::dbg_declare: + case Intrinsic::dbg_value: + case Intrinsic::invariant_start: + case Intrinsic::invariant_end: + case Intrinsic::lifetime_start: + case Intrinsic::lifetime_end: + case Intrinsic::objectsize: + case Intrinsic::ptr_annotation: + case Intrinsic::var_annotation: + return true; + } + + return false; +} + +static bool isValidAssumeForContext(Value *V, const Query &Q, + const DataLayout *DL) { + Instruction *Inv = cast(V); + + // There are two restrictions on the use of an assume: + // 1. The assume must dominate the context (or the control flow must + // reach the assume whenever it reaches the context). + // 2. The context must not be in the assume's set of ephemeral values + // (otherwise we will use the assume to prove that the condition + // feeding the assume is trivially true, thus causing the removal of + // the assume). + + if (Q.DT) { + if (Q.DT->dominates(Inv, Q.CxtI)) { + return true; + } else if (Inv->getParent() == Q.CxtI->getParent()) { + // The context comes first, but they're both in the same block. Make sure + // there is nothing in between that might interrupt the control flow. + for (BasicBlock::const_iterator I = + std::next(BasicBlock::const_iterator(Q.CxtI)), + IE(Inv); I != IE; ++I) + if (!isSafeToSpeculativelyExecute(I, DL) && + !isAssumeLikeIntrinsic(I)) + return false; + + return !isEphemeralValueOf(Inv, Q.CxtI); + } + + return false; + } + + // When we don't have a DT, we do a limited search... + if (Inv->getParent() == Q.CxtI->getParent()->getSinglePredecessor()) { + return true; + } else if (Inv->getParent() == Q.CxtI->getParent()) { + // Search forward from the assume until we reach the context (or the end + // of the block); the common case is that the assume will come first. + for (BasicBlock::iterator I = std::next(BasicBlock::iterator(Inv)), + IE = Inv->getParent()->end(); I != IE; ++I) + if (I == Q.CxtI) + return true; + + // The context must come first... + for (BasicBlock::const_iterator I = + std::next(BasicBlock::const_iterator(Q.CxtI)), + IE(Inv); I != IE; ++I) + if (!isSafeToSpeculativelyExecute(I, DL) && + !isAssumeLikeIntrinsic(I)) + return false; + + return !isEphemeralValueOf(Inv, Q.CxtI); + } + + return false; +} + +bool llvm::isValidAssumeForContext(const Instruction *I, + const Instruction *CxtI, + const DataLayout *DL, + const DominatorTree *DT) { + return ::isValidAssumeForContext(const_cast(I), + Query(nullptr, CxtI, DT), DL); +} + +template +inline match_combine_or, + CmpClass_match> +m_c_ICmp(ICmpInst::Predicate &Pred, const LHS &L, const RHS &R) { + return m_CombineOr(m_ICmp(Pred, L, R), m_ICmp(Pred, R, L)); +} + +template +inline match_combine_or, + BinaryOp_match> +m_c_And(const LHS &L, const RHS &R) { + return m_CombineOr(m_And(L, R), m_And(R, L)); +} + +template +inline match_combine_or, + BinaryOp_match> +m_c_Or(const LHS &L, const RHS &R) { + return m_CombineOr(m_Or(L, R), m_Or(R, L)); +} + +template +inline match_combine_or, + BinaryOp_match> +m_c_Xor(const LHS &L, const RHS &R) { + return m_CombineOr(m_Xor(L, R), m_Xor(R, L)); +} + +static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero, + APInt &KnownOne, + const DataLayout *DL, + unsigned Depth, const Query &Q) { + // Use of assumptions is context-sensitive. If we don't have a context, we + // cannot use them! + if (!Q.AT || !Q.CxtI) + return; + + unsigned BitWidth = KnownZero.getBitWidth(); + + Function *F = const_cast(Q.CxtI->getParent()->getParent()); + for (auto &CI : Q.AT->assumptions(F)) { + CallInst *I = CI; + if (Q.ExclInvs.count(I)) + continue; + + // Warning: This loop can end up being somewhat performance sensetive. + // We're running this loop for once for each value queried resulting in a + // runtime of ~O(#assumes * #values). + + assert(isa(I) && + dyn_cast(I)->getIntrinsicID() == Intrinsic::assume && + "must be an assume intrinsic"); + + Value *Arg = I->getArgOperand(0); + + if (Arg == V && + isValidAssumeForContext(I, Q, DL)) { + assert(BitWidth == 1 && "assume operand is not i1?"); + KnownZero.clearAllBits(); + KnownOne.setAllBits(); + return; + } + + // The remaining tests are all recursive, so bail out if we hit the limit. + if (Depth == MaxDepth) + continue; + + Value *A, *B; + auto m_V = m_CombineOr(m_Specific(V), + m_CombineOr(m_PtrToInt(m_Specific(V)), + m_BitCast(m_Specific(V)))); + + CmpInst::Predicate Pred; + ConstantInt *C; + // assume(v = a) + if (match(Arg, m_c_ICmp(Pred, m_V, m_Value(A))) && + Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + KnownZero |= RHSKnownZero; + KnownOne |= RHSKnownOne; + // assume(v & b = a) + } else if (match(Arg, m_c_ICmp(Pred, m_c_And(m_V, m_Value(B)), + m_Value(A))) && + Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + APInt MaskKnownZero(BitWidth, 0), MaskKnownOne(BitWidth, 0); + computeKnownBits(B, MaskKnownZero, MaskKnownOne, DL, Depth+1, Query(Q, I)); + + // For those bits in the mask that are known to be one, we can propagate + // known bits from the RHS to V. + KnownZero |= RHSKnownZero & MaskKnownOne; + KnownOne |= RHSKnownOne & MaskKnownOne; + // assume(~(v & b) = a) + } else if (match(Arg, m_c_ICmp(Pred, m_Not(m_c_And(m_V, m_Value(B))), + m_Value(A))) && + Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + APInt MaskKnownZero(BitWidth, 0), MaskKnownOne(BitWidth, 0); + computeKnownBits(B, MaskKnownZero, MaskKnownOne, DL, Depth+1, Query(Q, I)); + + // For those bits in the mask that are known to be one, we can propagate + // inverted known bits from the RHS to V. + KnownZero |= RHSKnownOne & MaskKnownOne; + KnownOne |= RHSKnownZero & MaskKnownOne; + // assume(v | b = a) + } else if (match(Arg, m_c_ICmp(Pred, m_c_Or(m_V, m_Value(B)), + m_Value(A))) && + Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + APInt BKnownZero(BitWidth, 0), BKnownOne(BitWidth, 0); + computeKnownBits(B, BKnownZero, BKnownOne, DL, Depth+1, Query(Q, I)); + + // For those bits in B that are known to be zero, we can propagate known + // bits from the RHS to V. + KnownZero |= RHSKnownZero & BKnownZero; + KnownOne |= RHSKnownOne & BKnownZero; + // assume(~(v | b) = a) + } else if (match(Arg, m_c_ICmp(Pred, m_Not(m_c_Or(m_V, m_Value(B))), + m_Value(A))) && + Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + APInt BKnownZero(BitWidth, 0), BKnownOne(BitWidth, 0); + computeKnownBits(B, BKnownZero, BKnownOne, DL, Depth+1, Query(Q, I)); + + // For those bits in B that are known to be zero, we can propagate + // inverted known bits from the RHS to V. + KnownZero |= RHSKnownOne & BKnownZero; + KnownOne |= RHSKnownZero & BKnownZero; + // assume(v ^ b = a) + } else if (match(Arg, m_c_ICmp(Pred, m_c_Xor(m_V, m_Value(B)), + m_Value(A))) && + Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + APInt BKnownZero(BitWidth, 0), BKnownOne(BitWidth, 0); + computeKnownBits(B, BKnownZero, BKnownOne, DL, Depth+1, Query(Q, I)); + + // For those bits in B that are known to be zero, we can propagate known + // bits from the RHS to V. For those bits in B that are known to be one, + // we can propagate inverted known bits from the RHS to V. + KnownZero |= RHSKnownZero & BKnownZero; + KnownOne |= RHSKnownOne & BKnownZero; + KnownZero |= RHSKnownOne & BKnownOne; + KnownOne |= RHSKnownZero & BKnownOne; + // assume(~(v ^ b) = a) + } else if (match(Arg, m_c_ICmp(Pred, m_Not(m_c_Xor(m_V, m_Value(B))), + m_Value(A))) && + Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + APInt BKnownZero(BitWidth, 0), BKnownOne(BitWidth, 0); + computeKnownBits(B, BKnownZero, BKnownOne, DL, Depth+1, Query(Q, I)); + + // For those bits in B that are known to be zero, we can propagate + // inverted known bits from the RHS to V. For those bits in B that are + // known to be one, we can propagate known bits from the RHS to V. + KnownZero |= RHSKnownOne & BKnownZero; + KnownOne |= RHSKnownZero & BKnownZero; + KnownZero |= RHSKnownZero & BKnownOne; + KnownOne |= RHSKnownOne & BKnownOne; + // assume(v << c = a) + } else if (match(Arg, m_c_ICmp(Pred, m_Shl(m_V, m_ConstantInt(C)), + m_Value(A))) && + Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + // For those bits in RHS that are known, we can propagate them to known + // bits in V shifted to the right by C. + KnownZero |= RHSKnownZero.lshr(C->getZExtValue()); + KnownOne |= RHSKnownOne.lshr(C->getZExtValue()); + // assume(~(v << c) = a) + } else if (match(Arg, m_c_ICmp(Pred, m_Not(m_Shl(m_V, m_ConstantInt(C))), + m_Value(A))) && + Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + // For those bits in RHS that are known, we can propagate them inverted + // to known bits in V shifted to the right by C. + KnownZero |= RHSKnownOne.lshr(C->getZExtValue()); + KnownOne |= RHSKnownZero.lshr(C->getZExtValue()); + // assume(v >> c = a) + } else if (match(Arg, + m_c_ICmp(Pred, m_CombineOr(m_LShr(m_V, m_ConstantInt(C)), + m_AShr(m_V, + m_ConstantInt(C))), + m_Value(A))) && + Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + // For those bits in RHS that are known, we can propagate them to known + // bits in V shifted to the right by C. + KnownZero |= RHSKnownZero << C->getZExtValue(); + KnownOne |= RHSKnownOne << C->getZExtValue(); + // assume(~(v >> c) = a) + } else if (match(Arg, m_c_ICmp(Pred, m_Not(m_CombineOr( + m_LShr(m_V, m_ConstantInt(C)), + m_AShr(m_V, m_ConstantInt(C)))), + m_Value(A))) && + Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + // For those bits in RHS that are known, we can propagate them inverted + // to known bits in V shifted to the right by C. + KnownZero |= RHSKnownOne << C->getZExtValue(); + KnownOne |= RHSKnownZero << C->getZExtValue(); + // assume(v >=_s c) where c is non-negative + } else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) && + Pred == ICmpInst::ICMP_SGE && + isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + + if (RHSKnownZero.isNegative()) { + // We know that the sign bit is zero. + KnownZero |= APInt::getSignBit(BitWidth); + } + // assume(v >_s c) where c is at least -1. + } else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) && + Pred == ICmpInst::ICMP_SGT && + isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + + if (RHSKnownOne.isAllOnesValue() || RHSKnownZero.isNegative()) { + // We know that the sign bit is zero. + KnownZero |= APInt::getSignBit(BitWidth); + } + // assume(v <=_s c) where c is negative + } else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) && + Pred == ICmpInst::ICMP_SLE && + isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + + if (RHSKnownOne.isNegative()) { + // We know that the sign bit is one. + KnownOne |= APInt::getSignBit(BitWidth); + } + // assume(v <_s c) where c is non-positive + } else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) && + Pred == ICmpInst::ICMP_SLT && + isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + + if (RHSKnownZero.isAllOnesValue() || RHSKnownOne.isNegative()) { + // We know that the sign bit is one. + KnownOne |= APInt::getSignBit(BitWidth); + } + // assume(v <=_u c) + } else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) && + Pred == ICmpInst::ICMP_ULE && + isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + + // Whatever high bits in c are zero are known to be zero. + KnownZero |= + APInt::getHighBitsSet(BitWidth, RHSKnownZero.countLeadingOnes()); + // assume(v <_u c) + } else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) && + Pred == ICmpInst::ICMP_ULT && + isValidAssumeForContext(I, Q, DL)) { + APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0); + computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I)); + + // Whatever high bits in c are zero are known to be zero (if c is a power + // of 2, then one more). + if (isKnownToBeAPowerOfTwo(A, false, Depth+1, Query(Q, I))) + KnownZero |= + APInt::getHighBitsSet(BitWidth, RHSKnownZero.countLeadingOnes()+1); + else + KnownZero |= + APInt::getHighBitsSet(BitWidth, RHSKnownZero.countLeadingOnes()); + } + } +} + +/// Determine which bits of V are known to be either zero or one and return +/// them in the KnownZero/KnownOne bit sets. /// /// NOTE: we cannot consider 'undef' to be "IsZero" here. The problem is that /// we cannot optimize based on the assumption that it is zero without changing @@ -225,8 +746,9 @@ void llvm::computeMaskedBitsLoad(const MDNode &Ranges, APInt &KnownZero) { /// where V is a vector, known zero, and known one values are the /// same width as the vector element, and the bit is set only if it is true /// for all of the elements in the vector. -void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, - const TargetData *TD, unsigned Depth) { +void computeKnownBits(Value *V, APInt &KnownZero, APInt &KnownOne, + const DataLayout *TD, unsigned Depth, + const Query &Q) { assert(V && "No Value?"); assert(Depth <= MaxDepth && "Limit Search Depth"); unsigned BitWidth = KnownZero.getBitWidth(); @@ -240,7 +762,7 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, V->getType()->getScalarSizeInBits() == BitWidth) && KnownZero.getBitWidth() == BitWidth && KnownOne.getBitWidth() == BitWidth && - "V, Mask, KnownOne and KnownZero should have same BitWidth"); + "V, KnownOne and KnownZero should have same BitWidth"); if (ConstantInt *CI = dyn_cast(V)) { // We know all of the bits for a constant! @@ -266,16 +788,16 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) { Elt = CDS->getElementAsInteger(i); KnownZero &= ~Elt; - KnownOne &= Elt; + KnownOne &= Elt; } return; } - + // The address of an aligned GlobalValue has trailing zeros. - if (GlobalValue *GV = dyn_cast(V)) { - unsigned Align = GV->getAlignment(); + if (auto *GO = dyn_cast(V)) { + unsigned Align = GO->getAlignment(); if (Align == 0 && TD) { - if (GlobalVariable *GVar = dyn_cast(GV)) { + if (auto *GVar = dyn_cast(GO)) { Type *ObjectType = GVar->getType()->getElementType(); if (ObjectType->isSized()) { // If the object is defined in the current Module, we'll be giving @@ -290,37 +812,50 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, } if (Align > 0) KnownZero = APInt::getLowBitsSet(BitWidth, - CountTrailingZeros_32(Align)); + countTrailingZeros(Align)); else KnownZero.clearAllBits(); KnownOne.clearAllBits(); return; } - // A weak GlobalAlias is totally unknown. A non-weak GlobalAlias has - // the bits of its aliasee. - if (GlobalAlias *GA = dyn_cast(V)) { - if (GA->mayBeOverridden()) { - KnownZero.clearAllBits(); KnownOne.clearAllBits(); - } else { - ComputeMaskedBits(GA->getAliasee(), KnownZero, KnownOne, TD, Depth+1); - } - return; - } - + if (Argument *A = dyn_cast(V)) { - // Get alignment information off byval arguments if specified in the IR. - if (A->hasByValAttr()) - if (unsigned Align = A->getParamAlignment()) - KnownZero = APInt::getLowBitsSet(BitWidth, - CountTrailingZeros_32(Align)); + unsigned Align = A->getType()->isPointerTy() ? A->getParamAlignment() : 0; + + if (!Align && TD && A->hasStructRetAttr()) { + // An sret parameter has at least the ABI alignment of the return type. + Type *EltTy = cast(A->getType())->getElementType(); + if (EltTy->isSized()) + Align = TD->getABITypeAlignment(EltTy); + } + + if (Align) + KnownZero = APInt::getLowBitsSet(BitWidth, countTrailingZeros(Align)); + + // Don't give up yet... there might be an assumption that provides more + // information... + computeKnownBitsFromAssume(V, KnownZero, KnownOne, TD, Depth, Q); return; } // Start out not knowing anything. KnownZero.clearAllBits(); KnownOne.clearAllBits(); + // Limit search depth. + // All recursive calls that increase depth must come after this. if (Depth == MaxDepth) - return; // Limit search depth. + return; + + // A weak GlobalAlias is totally unknown. A non-weak GlobalAlias has + // the bits of its aliasee. + if (GlobalAlias *GA = dyn_cast(V)) { + if (!GA->mayBeOverridden()) + computeKnownBits(GA->getAliasee(), KnownZero, KnownOne, TD, Depth + 1, Q); + return; + } + + // Check whether a nearby assume intrinsic can determine some known bits. + computeKnownBitsFromAssume(V, KnownZero, KnownOne, TD, Depth, Q); Operator *I = dyn_cast(V); if (!I) return; @@ -330,114 +865,110 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, default: break; case Instruction::Load: if (MDNode *MD = cast(I)->getMetadata(LLVMContext::MD_range)) - computeMaskedBitsLoad(*MD, KnownZero); - return; + computeKnownBitsFromRangeMetadata(*MD, KnownZero); + break; case Instruction::And: { // If either the LHS or the RHS are Zero, the result is zero. - ComputeMaskedBits(I->getOperand(1), KnownZero, KnownOne, TD, Depth+1); - ComputeMaskedBits(I->getOperand(0), KnownZero2, KnownOne2, TD, Depth+1); - assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); - assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); - + computeKnownBits(I->getOperand(1), KnownZero, KnownOne, TD, Depth+1, Q); + computeKnownBits(I->getOperand(0), KnownZero2, KnownOne2, TD, Depth+1, Q); + // Output known-1 bits are only known if set in both the LHS & RHS. KnownOne &= KnownOne2; // Output known-0 are known to be clear if zero in either the LHS | RHS. KnownZero |= KnownZero2; - return; + break; } case Instruction::Or: { - ComputeMaskedBits(I->getOperand(1), KnownZero, KnownOne, TD, Depth+1); - ComputeMaskedBits(I->getOperand(0), KnownZero2, KnownOne2, TD, Depth+1); - assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); - assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); - + computeKnownBits(I->getOperand(1), KnownZero, KnownOne, TD, Depth+1, Q); + computeKnownBits(I->getOperand(0), KnownZero2, KnownOne2, TD, Depth+1, Q); + // Output known-0 bits are only known if clear in both the LHS & RHS. KnownZero &= KnownZero2; // Output known-1 are known to be set if set in either the LHS | RHS. KnownOne |= KnownOne2; - return; + break; } case Instruction::Xor: { - ComputeMaskedBits(I->getOperand(1), KnownZero, KnownOne, TD, Depth+1); - ComputeMaskedBits(I->getOperand(0), KnownZero2, KnownOne2, TD, Depth+1); - assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); - assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); - + computeKnownBits(I->getOperand(1), KnownZero, KnownOne, TD, Depth+1, Q); + computeKnownBits(I->getOperand(0), KnownZero2, KnownOne2, TD, Depth+1, Q); + // Output known-0 bits are known if clear or set in both the LHS & RHS. APInt KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2); // Output known-1 are known to be set if set in only one of the LHS, RHS. KnownOne = (KnownZero & KnownOne2) | (KnownOne & KnownZero2); KnownZero = KnownZeroOut; - return; + break; } case Instruction::Mul: { bool NSW = cast(I)->hasNoSignedWrap(); - ComputeMaskedBitsMul(I->getOperand(0), I->getOperand(1), NSW, - KnownZero, KnownOne, KnownZero2, KnownOne2, TD, Depth); + computeKnownBitsMul(I->getOperand(0), I->getOperand(1), NSW, + KnownZero, KnownOne, KnownZero2, KnownOne2, TD, + Depth, Q); break; } case Instruction::UDiv: { // For the purposes of computing leading zeros we can conservatively // treat a udiv as a logical right shift by the power of 2 known to // be less than the denominator. - ComputeMaskedBits(I->getOperand(0), KnownZero2, KnownOne2, TD, Depth+1); + computeKnownBits(I->getOperand(0), KnownZero2, KnownOne2, TD, Depth+1, Q); unsigned LeadZ = KnownZero2.countLeadingOnes(); KnownOne2.clearAllBits(); KnownZero2.clearAllBits(); - ComputeMaskedBits(I->getOperand(1), KnownZero2, KnownOne2, TD, Depth+1); + computeKnownBits(I->getOperand(1), KnownZero2, KnownOne2, TD, Depth+1, Q); unsigned RHSUnknownLeadingOnes = KnownOne2.countLeadingZeros(); if (RHSUnknownLeadingOnes != BitWidth) LeadZ = std::min(BitWidth, LeadZ + BitWidth - RHSUnknownLeadingOnes - 1); KnownZero = APInt::getHighBitsSet(BitWidth, LeadZ); - return; + break; } case Instruction::Select: - ComputeMaskedBits(I->getOperand(2), KnownZero, KnownOne, TD, Depth+1); - ComputeMaskedBits(I->getOperand(1), KnownZero2, KnownOne2, TD, - Depth+1); - assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); - assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); + computeKnownBits(I->getOperand(2), KnownZero, KnownOne, TD, Depth+1, Q); + computeKnownBits(I->getOperand(1), KnownZero2, KnownOne2, TD, Depth+1, Q); // Only known if known in both the LHS and RHS. KnownOne &= KnownOne2; KnownZero &= KnownZero2; - return; + break; case Instruction::FPTrunc: case Instruction::FPExt: case Instruction::FPToUI: case Instruction::FPToSI: case Instruction::SIToFP: case Instruction::UIToFP: - return; // Can't work with floating point. + break; // Can't work with floating point. case Instruction::PtrToInt: case Instruction::IntToPtr: + case Instruction::AddrSpaceCast: // Pointers could be different sizes. // We can't handle these if we don't know the pointer size. - if (!TD) return; + if (!TD) break; // FALL THROUGH and handle them the same as zext/trunc. case Instruction::ZExt: case Instruction::Trunc: { Type *SrcTy = I->getOperand(0)->getType(); - + unsigned SrcBitWidth; // Note that we handle pointer operands here because of inttoptr/ptrtoint // which fall through here. - if (SrcTy->isPointerTy()) - SrcBitWidth = TD->getTypeSizeInBits(SrcTy); - else + if(TD) { + SrcBitWidth = TD->getTypeSizeInBits(SrcTy->getScalarType()); + } else { SrcBitWidth = SrcTy->getScalarSizeInBits(); - + if (!SrcBitWidth) break; + } + + assert(SrcBitWidth && "SrcBitWidth can't be zero"); KnownZero = KnownZero.zextOrTrunc(SrcBitWidth); KnownOne = KnownOne.zextOrTrunc(SrcBitWidth); - ComputeMaskedBits(I->getOperand(0), KnownZero, KnownOne, TD, Depth+1); + computeKnownBits(I->getOperand(0), KnownZero, KnownOne, TD, Depth+1, Q); KnownZero = KnownZero.zextOrTrunc(BitWidth); KnownOne = KnownOne.zextOrTrunc(BitWidth); // Any top bits are known to be zero. if (BitWidth > SrcBitWidth) KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth); - return; + break; } case Instruction::BitCast: { Type *SrcTy = I->getOperand(0)->getType(); @@ -445,19 +976,18 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, // TODO: For now, not handling conversions like: // (bitcast i64 %x to <2 x i32>) !I->getType()->isVectorTy()) { - ComputeMaskedBits(I->getOperand(0), KnownZero, KnownOne, TD, Depth+1); - return; + computeKnownBits(I->getOperand(0), KnownZero, KnownOne, TD, Depth+1, Q); + break; } break; } case Instruction::SExt: { // Compute the bits in the result that are not present in the input. unsigned SrcBitWidth = I->getOperand(0)->getType()->getScalarSizeInBits(); - + KnownZero = KnownZero.trunc(SrcBitWidth); KnownOne = KnownOne.trunc(SrcBitWidth); - ComputeMaskedBits(I->getOperand(0), KnownZero, KnownOne, TD, Depth+1); - assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); + computeKnownBits(I->getOperand(0), KnownZero, KnownOne, TD, Depth+1, Q); KnownZero = KnownZero.zext(BitWidth); KnownOne = KnownOne.zext(BitWidth); @@ -467,18 +997,16 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth); else if (KnownOne[SrcBitWidth-1]) // Input sign bit known set KnownOne |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth); - return; + break; } case Instruction::Shl: // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0 if (ConstantInt *SA = dyn_cast(I->getOperand(1))) { uint64_t ShiftAmt = SA->getLimitedValue(BitWidth); - ComputeMaskedBits(I->getOperand(0), KnownZero, KnownOne, TD, Depth+1); - assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); + computeKnownBits(I->getOperand(0), KnownZero, KnownOne, TD, Depth+1, Q); KnownZero <<= ShiftAmt; KnownOne <<= ShiftAmt; KnownZero |= APInt::getLowBitsSet(BitWidth, ShiftAmt); // low bits known 0 - return; } break; case Instruction::LShr: @@ -486,15 +1014,13 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, if (ConstantInt *SA = dyn_cast(I->getOperand(1))) { // Compute the new bits that are at the top now. uint64_t ShiftAmt = SA->getLimitedValue(BitWidth); - + // Unsigned shift right. - ComputeMaskedBits(I->getOperand(0), KnownZero,KnownOne, TD, Depth+1); - assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); + computeKnownBits(I->getOperand(0), KnownZero, KnownOne, TD, Depth+1, Q); KnownZero = APIntOps::lshr(KnownZero, ShiftAmt); KnownOne = APIntOps::lshr(KnownOne, ShiftAmt); // high bits known zero. KnownZero |= APInt::getHighBitsSet(BitWidth, ShiftAmt); - return; } break; case Instruction::AShr: @@ -502,33 +1028,31 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, if (ConstantInt *SA = dyn_cast(I->getOperand(1))) { // Compute the new bits that are at the top now. uint64_t ShiftAmt = SA->getLimitedValue(BitWidth-1); - + // Signed shift right. - ComputeMaskedBits(I->getOperand(0), KnownZero, KnownOne, TD, Depth+1); - assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); + computeKnownBits(I->getOperand(0), KnownZero, KnownOne, TD, Depth+1, Q); KnownZero = APIntOps::lshr(KnownZero, ShiftAmt); KnownOne = APIntOps::lshr(KnownOne, ShiftAmt); - + APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt)); if (KnownZero[BitWidth-ShiftAmt-1]) // New bits are known zero. KnownZero |= HighBits; else if (KnownOne[BitWidth-ShiftAmt-1]) // New bits are known one. KnownOne |= HighBits; - return; } break; case Instruction::Sub: { bool NSW = cast(I)->hasNoSignedWrap(); - ComputeMaskedBitsAddSub(false, I->getOperand(0), I->getOperand(1), NSW, + computeKnownBitsAddSub(false, I->getOperand(0), I->getOperand(1), NSW, KnownZero, KnownOne, KnownZero2, KnownOne2, TD, - Depth); + Depth, Q); break; } case Instruction::Add: { bool NSW = cast(I)->hasNoSignedWrap(); - ComputeMaskedBitsAddSub(true, I->getOperand(0), I->getOperand(1), NSW, + computeKnownBitsAddSub(true, I->getOperand(0), I->getOperand(1), NSW, KnownZero, KnownOne, KnownZero2, KnownOne2, TD, - Depth); + Depth, Q); break; } case Instruction::SRem: @@ -536,7 +1060,8 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, APInt RA = Rem->getValue().abs(); if (RA.isPowerOf2()) { APInt LowBits = RA - 1; - ComputeMaskedBits(I->getOperand(0), KnownZero2, KnownOne2, TD, Depth+1); + computeKnownBits(I->getOperand(0), KnownZero2, KnownOne2, TD, + Depth+1, Q); // The low bits of the first operand are unchanged by the srem. KnownZero = KnownZero2 & LowBits; @@ -552,7 +1077,7 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, if (KnownOne2[BitWidth-1] && ((KnownOne2 & LowBits) != 0)) KnownOne |= ~LowBits; - assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); + assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); } } @@ -560,8 +1085,8 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, // remainder is zero. if (KnownZero.isNonNegative()) { APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0); - ComputeMaskedBits(I->getOperand(0), LHSKnownZero, LHSKnownOne, TD, - Depth+1); + computeKnownBits(I->getOperand(0), LHSKnownZero, LHSKnownOne, TD, + Depth+1, Q); // If it's known zero, our sign bit is also zero. if (LHSKnownZero.isNegative()) KnownZero.setBit(BitWidth - 1); @@ -573,9 +1098,8 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, APInt RA = Rem->getValue(); if (RA.isPowerOf2()) { APInt LowBits = (RA - 1); - ComputeMaskedBits(I->getOperand(0), KnownZero, KnownOne, TD, - Depth+1); - assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); + computeKnownBits(I->getOperand(0), KnownZero, KnownOne, TD, + Depth+1, Q); KnownZero |= ~LowBits; KnownOne &= LowBits; break; @@ -584,8 +1108,8 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, // Since the result is less than or equal to either operand, any leading // zero bits in either operand must also exist in the result. - ComputeMaskedBits(I->getOperand(0), KnownZero, KnownOne, TD, Depth+1); - ComputeMaskedBits(I->getOperand(1), KnownZero2, KnownOne2, TD, Depth+1); + computeKnownBits(I->getOperand(0), KnownZero, KnownOne, TD, Depth+1, Q); + computeKnownBits(I->getOperand(1), KnownZero2, KnownOne2, TD, Depth+1, Q); unsigned Leaders = std::max(KnownZero.countLeadingOnes(), KnownZero2.countLeadingOnes()); @@ -599,17 +1123,17 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, unsigned Align = AI->getAlignment(); if (Align == 0 && TD) Align = TD->getABITypeAlignment(AI->getType()->getElementType()); - + if (Align > 0) - KnownZero = APInt::getLowBitsSet(BitWidth, CountTrailingZeros_32(Align)); + KnownZero = APInt::getLowBitsSet(BitWidth, countTrailingZeros(Align)); break; } case Instruction::GetElementPtr: { // Analyze all of the subscripts of this getelementptr instruction // to determine if we can prove known low zero bits. APInt LocalKnownZero(BitWidth, 0), LocalKnownOne(BitWidth, 0); - ComputeMaskedBits(I->getOperand(0), LocalKnownZero, LocalKnownOne, TD, - Depth+1); + computeKnownBits(I->getOperand(0), LocalKnownZero, LocalKnownOne, TD, + Depth+1, Q); unsigned TrailZ = LocalKnownZero.countTrailingOnes(); gep_type_iterator GTI = gep_type_begin(I); @@ -617,26 +1141,41 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, Value *Index = I->getOperand(i); if (StructType *STy = dyn_cast(*GTI)) { // Handle struct member offset arithmetic. - if (!TD) return; - const StructLayout *SL = TD->getStructLayout(STy); + if (!TD) { + TrailZ = 0; + break; + } + + // Handle case when index is vector zeroinitializer + Constant *CIndex = cast(Index); + if (CIndex->isZeroValue()) + continue; + + if (CIndex->getType()->isVectorTy()) + Index = CIndex->getSplatValue(); + unsigned Idx = cast(Index)->getZExtValue(); + const StructLayout *SL = TD->getStructLayout(STy); uint64_t Offset = SL->getElementOffset(Idx); - TrailZ = std::min(TrailZ, - CountTrailingZeros_64(Offset)); + TrailZ = std::min(TrailZ, + countTrailingZeros(Offset)); } else { // Handle array index arithmetic. Type *IndexedTy = GTI.getIndexedType(); - if (!IndexedTy->isSized()) return; + if (!IndexedTy->isSized()) { + TrailZ = 0; + break; + } unsigned GEPOpiBits = Index->getType()->getScalarSizeInBits(); uint64_t TypeSize = TD ? TD->getTypeAllocSize(IndexedTy) : 1; LocalKnownZero = LocalKnownOne = APInt(GEPOpiBits, 0); - ComputeMaskedBits(Index, LocalKnownZero, LocalKnownOne, TD, Depth+1); + computeKnownBits(Index, LocalKnownZero, LocalKnownOne, TD, Depth+1, Q); TrailZ = std::min(TrailZ, - unsigned(CountTrailingZeros_64(TypeSize) + + unsigned(countTrailingZeros(TypeSize) + LocalKnownZero.countTrailingOnes())); } } - + KnownZero = APInt::getLowBitsSet(BitWidth, TrailZ); break; } @@ -672,11 +1211,11 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, break; // Ok, we have a PHI of the form L op= R. Check for low // zero bits. - ComputeMaskedBits(R, KnownZero2, KnownOne2, TD, Depth+1); + computeKnownBits(R, KnownZero2, KnownOne2, TD, Depth+1, Q); // We need to take the minimum number of known bits APInt KnownZero3(KnownZero), KnownOne3(KnownOne); - ComputeMaskedBits(L, KnownZero3, KnownOne3, TD, Depth+1); + computeKnownBits(L, KnownZero3, KnownOne3, TD, Depth+1, Q); KnownZero = APInt::getLowBitsSet(BitWidth, std::min(KnownZero2.countTrailingOnes(), @@ -688,13 +1227,13 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, // Unreachable blocks may have zero-operand PHI nodes. if (P->getNumIncomingValues() == 0) - return; + break; // Otherwise take the unions of the known bit sets of the operands, // taking conservative care to avoid excessive recursion. if (Depth < MaxDepth - 1 && !KnownZero && !KnownOne) { // Skip if every incoming value references to ourself. - if (P->hasConstantValue() == P) + if (dyn_cast_or_null(P->hasConstantValue())) break; KnownZero = APInt::getAllOnesValue(BitWidth); @@ -707,8 +1246,8 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, KnownOne2 = APInt(BitWidth, 0); // Recurse, but cap the recursion to one level, because we don't // want to waste time spinning around in loops. - ComputeMaskedBits(P->getIncomingValue(i), KnownZero2, KnownOne2, TD, - MaxDepth-1); + computeKnownBits(P->getIncomingValue(i), KnownZero2, KnownOne2, TD, + MaxDepth-1, Q); KnownZero &= KnownZero2; KnownOne &= KnownOne2; // If all bits have been ruled out, there's no need to check @@ -720,6 +1259,12 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, break; } case Instruction::Call: + case Instruction::Invoke: + if (MDNode *MD = cast(I)->getMetadata(LLVMContext::MD_range)) + computeKnownBitsFromRangeMetadata(*MD, KnownZero); + // If a range metadata is attached to this IntrinsicInst, intersect the + // explicit range specified by the metadata and the implicit range of + // the intrinsic. if (IntrinsicInst *II = dyn_cast(I)) { switch (II->getIntrinsicID()) { default: break; @@ -729,17 +1274,16 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, // If this call is undefined for 0, the result will be less than 2^n. if (II->getArgOperand(1) == ConstantInt::getTrue(II->getContext())) LowBits -= 1; - KnownZero = APInt::getHighBitsSet(BitWidth, BitWidth - LowBits); + KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - LowBits); break; } case Intrinsic::ctpop: { unsigned LowBits = Log2_32(BitWidth)+1; - KnownZero = APInt::getHighBitsSet(BitWidth, BitWidth - LowBits); + KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - LowBits); break; } - case Intrinsic::x86_sse42_crc32_64_8: case Intrinsic::x86_sse42_crc32_64_64: - KnownZero = APInt::getHighBitsSet(64, 32); + KnownZero |= APInt::getHighBitsSet(64, 32); break; } } @@ -753,32 +1297,35 @@ void llvm::ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne, default: break; case Intrinsic::uadd_with_overflow: case Intrinsic::sadd_with_overflow: - ComputeMaskedBitsAddSub(true, II->getArgOperand(0), - II->getArgOperand(1), false, KnownZero, - KnownOne, KnownZero2, KnownOne2, TD, Depth); + computeKnownBitsAddSub(true, II->getArgOperand(0), + II->getArgOperand(1), false, KnownZero, + KnownOne, KnownZero2, KnownOne2, TD, Depth, Q); break; case Intrinsic::usub_with_overflow: case Intrinsic::ssub_with_overflow: - ComputeMaskedBitsAddSub(false, II->getArgOperand(0), - II->getArgOperand(1), false, KnownZero, - KnownOne, KnownZero2, KnownOne2, TD, Depth); + computeKnownBitsAddSub(false, II->getArgOperand(0), + II->getArgOperand(1), false, KnownZero, + KnownOne, KnownZero2, KnownOne2, TD, Depth, Q); break; case Intrinsic::umul_with_overflow: case Intrinsic::smul_with_overflow: - ComputeMaskedBitsMul(II->getArgOperand(0), II->getArgOperand(1), - false, KnownZero, KnownOne, - KnownZero2, KnownOne2, TD, Depth); + computeKnownBitsMul(II->getArgOperand(0), II->getArgOperand(1), + false, KnownZero, KnownOne, + KnownZero2, KnownOne2, TD, Depth, Q); break; } } } } + + assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); } -/// ComputeSignBit - Determine whether the sign bit is known to be zero or -/// one. Convenience wrapper around ComputeMaskedBits. -void llvm::ComputeSignBit(Value *V, bool &KnownZero, bool &KnownOne, - const TargetData *TD, unsigned Depth) { +/// Determine whether the sign bit is known to be zero or one. +/// Convenience wrapper around computeKnownBits. +void ComputeSignBit(Value *V, bool &KnownZero, bool &KnownOne, + const DataLayout *TD, unsigned Depth, + const Query &Q) { unsigned BitWidth = getBitWidth(V->getType(), TD); if (!BitWidth) { KnownZero = false; @@ -787,17 +1334,17 @@ void llvm::ComputeSignBit(Value *V, bool &KnownZero, bool &KnownOne, } APInt ZeroBits(BitWidth, 0); APInt OneBits(BitWidth, 0); - ComputeMaskedBits(V, ZeroBits, OneBits, TD, Depth); + computeKnownBits(V, ZeroBits, OneBits, TD, Depth, Q); KnownOne = OneBits[BitWidth - 1]; KnownZero = ZeroBits[BitWidth - 1]; } -/// isPowerOfTwo - Return true if the given value is known to have exactly one +/// Return true if the given value is known to have exactly one /// bit set when defined. For vectors return true if every element is known to -/// be a power of two when defined. Supports values with integer or pointer +/// be a power of two when defined. Supports values with integer or pointer /// types and vectors of integers. -bool llvm::isPowerOfTwo(Value *V, const TargetData *TD, bool OrZero, - unsigned Depth) { +bool isKnownToBeAPowerOfTwo(Value *V, bool OrZero, unsigned Depth, + const Query &Q) { if (Constant *C = dyn_cast(V)) { if (C->isNullValue()) return OrZero; @@ -820,23 +1367,24 @@ bool llvm::isPowerOfTwo(Value *V, const TargetData *TD, bool OrZero, if (Depth++ == MaxDepth) return false; - Value *X = 0, *Y = 0; + Value *X = nullptr, *Y = nullptr; // A shift of a power of two is a power of two or zero. if (OrZero && (match(V, m_Shl(m_Value(X), m_Value())) || match(V, m_Shr(m_Value(X), m_Value())))) - return isPowerOfTwo(X, TD, /*OrZero*/true, Depth); + return isKnownToBeAPowerOfTwo(X, /*OrZero*/true, Depth, Q); if (ZExtInst *ZI = dyn_cast(V)) - return isPowerOfTwo(ZI->getOperand(0), TD, OrZero, Depth); + return isKnownToBeAPowerOfTwo(ZI->getOperand(0), OrZero, Depth, Q); if (SelectInst *SI = dyn_cast(V)) - return isPowerOfTwo(SI->getTrueValue(), TD, OrZero, Depth) && - isPowerOfTwo(SI->getFalseValue(), TD, OrZero, Depth); + return + isKnownToBeAPowerOfTwo(SI->getTrueValue(), OrZero, Depth, Q) && + isKnownToBeAPowerOfTwo(SI->getFalseValue(), OrZero, Depth, Q); if (OrZero && match(V, m_And(m_Value(X), m_Value(Y)))) { // A power of two and'd with anything is a power of two or zero. - if (isPowerOfTwo(X, TD, /*OrZero*/true, Depth) || - isPowerOfTwo(Y, TD, /*OrZero*/true, Depth)) + if (isKnownToBeAPowerOfTwo(X, /*OrZero*/true, Depth, Q) || + isKnownToBeAPowerOfTwo(Y, /*OrZero*/true, Depth, Q)) return true; // X & (-X) is always a power of two or zero. if (match(X, m_Neg(m_Specific(Y))) || match(Y, m_Neg(m_Specific(X)))) @@ -844,22 +1392,140 @@ bool llvm::isPowerOfTwo(Value *V, const TargetData *TD, bool OrZero, return false; } + // Adding a power-of-two or zero to the same power-of-two or zero yields + // either the original power-of-two, a larger power-of-two or zero. + if (match(V, m_Add(m_Value(X), m_Value(Y)))) { + OverflowingBinaryOperator *VOBO = cast(V); + if (OrZero || VOBO->hasNoUnsignedWrap() || VOBO->hasNoSignedWrap()) { + if (match(X, m_And(m_Specific(Y), m_Value())) || + match(X, m_And(m_Value(), m_Specific(Y)))) + if (isKnownToBeAPowerOfTwo(Y, OrZero, Depth, Q)) + return true; + if (match(Y, m_And(m_Specific(X), m_Value())) || + match(Y, m_And(m_Value(), m_Specific(X)))) + if (isKnownToBeAPowerOfTwo(X, OrZero, Depth, Q)) + return true; + + unsigned BitWidth = V->getType()->getScalarSizeInBits(); + APInt LHSZeroBits(BitWidth, 0), LHSOneBits(BitWidth, 0); + computeKnownBits(X, LHSZeroBits, LHSOneBits, nullptr, Depth, Q); + + APInt RHSZeroBits(BitWidth, 0), RHSOneBits(BitWidth, 0); + computeKnownBits(Y, RHSZeroBits, RHSOneBits, nullptr, Depth, Q); + // If i8 V is a power of two or zero: + // ZeroBits: 1 1 1 0 1 1 1 1 + // ~ZeroBits: 0 0 0 1 0 0 0 0 + if ((~(LHSZeroBits & RHSZeroBits)).isPowerOf2()) + // If OrZero isn't set, we cannot give back a zero result. + // Make sure either the LHS or RHS has a bit set. + if (OrZero || RHSOneBits.getBoolValue() || LHSOneBits.getBoolValue()) + return true; + } + } + // An exact divide or right shift can only shift off zero bits, so the result // is a power of two only if the first operand is a power of two and not // copying a sign bit (sdiv int_min, 2). if (match(V, m_Exact(m_LShr(m_Value(), m_Value()))) || match(V, m_Exact(m_UDiv(m_Value(), m_Value())))) { - return isPowerOfTwo(cast(V)->getOperand(0), TD, OrZero, Depth); + return isKnownToBeAPowerOfTwo(cast(V)->getOperand(0), OrZero, + Depth, Q); + } + + return false; +} + +/// \brief Test whether a GEP's result is known to be non-null. +/// +/// Uses properties inherent in a GEP to try to determine whether it is known +/// to be non-null. +/// +/// Currently this routine does not support vector GEPs. +static bool isGEPKnownNonNull(GEPOperator *GEP, const DataLayout *DL, + unsigned Depth, const Query &Q) { + if (!GEP->isInBounds() || GEP->getPointerAddressSpace() != 0) + return false; + + // FIXME: Support vector-GEPs. + assert(GEP->getType()->isPointerTy() && "We only support plain pointer GEP"); + + // If the base pointer is non-null, we cannot walk to a null address with an + // inbounds GEP in address space zero. + if (isKnownNonZero(GEP->getPointerOperand(), DL, Depth, Q)) + return true; + + // Past this, if we don't have DataLayout, we can't do much. + if (!DL) + return false; + + // Walk the GEP operands and see if any operand introduces a non-zero offset. + // If so, then the GEP cannot produce a null pointer, as doing so would + // inherently violate the inbounds contract within address space zero. + for (gep_type_iterator GTI = gep_type_begin(GEP), GTE = gep_type_end(GEP); + GTI != GTE; ++GTI) { + // Struct types are easy -- they must always be indexed by a constant. + if (StructType *STy = dyn_cast(*GTI)) { + ConstantInt *OpC = cast(GTI.getOperand()); + unsigned ElementIdx = OpC->getZExtValue(); + const StructLayout *SL = DL->getStructLayout(STy); + uint64_t ElementOffset = SL->getElementOffset(ElementIdx); + if (ElementOffset > 0) + return true; + continue; + } + + // If we have a zero-sized type, the index doesn't matter. Keep looping. + if (DL->getTypeAllocSize(GTI.getIndexedType()) == 0) + continue; + + // Fast path the constant operand case both for efficiency and so we don't + // increment Depth when just zipping down an all-constant GEP. + if (ConstantInt *OpC = dyn_cast(GTI.getOperand())) { + if (!OpC->isZero()) + return true; + continue; + } + + // We post-increment Depth here because while isKnownNonZero increments it + // as well, when we pop back up that increment won't persist. We don't want + // to recurse 10k times just because we have 10k GEP operands. We don't + // bail completely out because we want to handle constant GEPs regardless + // of depth. + if (Depth++ >= MaxDepth) + continue; + + if (isKnownNonZero(GTI.getOperand(), DL, Depth, Q)) + return true; } return false; } -/// isKnownNonZero - Return true if the given value is known to be non-zero -/// when defined. For vectors return true if every element is known to be -/// non-zero when defined. Supports values with integer or pointer type and -/// vectors of integers. -bool llvm::isKnownNonZero(Value *V, const TargetData *TD, unsigned Depth) { +/// Does the 'Range' metadata (which must be a valid MD_range operand list) +/// ensure that the value it's attached to is never Value? 'RangeType' is +/// is the type of the value described by the range. +static bool rangeMetadataExcludesValue(MDNode* Ranges, + const APInt& Value) { + const unsigned NumRanges = Ranges->getNumOperands() / 2; + assert(NumRanges >= 1); + for (unsigned i = 0; i < NumRanges; ++i) { + ConstantInt *Lower = + mdconst::extract(Ranges->getOperand(2 * i + 0)); + ConstantInt *Upper = + mdconst::extract(Ranges->getOperand(2 * i + 1)); + ConstantRange Range(Lower->getValue(), Upper->getValue()); + if (Range.contains(Value)) + return false; + } + return true; +} + +/// Return true if the given value is known to be non-zero when defined. +/// For vectors return true if every element is known to be non-zero when +/// defined. Supports values with integer or pointer type and vectors of +/// integers. +bool isKnownNonZero(Value *V, const DataLayout *TD, unsigned Depth, + const Query &Q) { if (Constant *C = dyn_cast(V)) { if (C->isNullValue()) return false; @@ -870,20 +1536,42 @@ bool llvm::isKnownNonZero(Value *V, const TargetData *TD, unsigned Depth) { return false; } + if (Instruction* I = dyn_cast(V)) { + if (MDNode *Ranges = I->getMetadata(LLVMContext::MD_range)) { + // If the possible ranges don't contain zero, then the value is + // definitely non-zero. + if (IntegerType* Ty = dyn_cast(V->getType())) { + const APInt ZeroValue(Ty->getBitWidth(), 0); + if (rangeMetadataExcludesValue(Ranges, ZeroValue)) + return true; + } + } + } + // The remaining tests are all recursive, so bail out if we hit the limit. if (Depth++ >= MaxDepth) return false; - unsigned BitWidth = getBitWidth(V->getType(), TD); + // Check for pointer simplifications. + if (V->getType()->isPointerTy()) { + if (isKnownNonNull(V)) + return true; + if (GEPOperator *GEP = dyn_cast(V)) + if (isGEPKnownNonNull(GEP, TD, Depth, Q)) + return true; + } + + unsigned BitWidth = getBitWidth(V->getType()->getScalarType(), TD); // X | Y != 0 if X != 0 or Y != 0. - Value *X = 0, *Y = 0; + Value *X = nullptr, *Y = nullptr; if (match(V, m_Or(m_Value(X), m_Value(Y)))) - return isKnownNonZero(X, TD, Depth) || isKnownNonZero(Y, TD, Depth); + return isKnownNonZero(X, TD, Depth, Q) || + isKnownNonZero(Y, TD, Depth, Q); // ext X != 0 if X != 0. if (isa(V) || isa(V)) - return isKnownNonZero(cast(V)->getOperand(0), TD, Depth); + return isKnownNonZero(cast(V)->getOperand(0), TD, Depth, Q); // shl X, Y != 0 if X is odd. Note that the value of the shift is undefined // if the lowest bit is shifted off the end. @@ -891,11 +1579,11 @@ bool llvm::isKnownNonZero(Value *V, const TargetData *TD, unsigned Depth) { // shl nuw can't remove any non-zero bits. OverflowingBinaryOperator *BO = cast(V); if (BO->hasNoUnsignedWrap()) - return isKnownNonZero(X, TD, Depth); + return isKnownNonZero(X, TD, Depth, Q); APInt KnownZero(BitWidth, 0); APInt KnownOne(BitWidth, 0); - ComputeMaskedBits(X, KnownZero, KnownOne, TD, Depth); + computeKnownBits(X, KnownZero, KnownOne, TD, Depth, Q); if (KnownOne[0]) return true; } @@ -905,28 +1593,29 @@ bool llvm::isKnownNonZero(Value *V, const TargetData *TD, unsigned Depth) { // shr exact can only shift out zero bits. PossiblyExactOperator *BO = cast(V); if (BO->isExact()) - return isKnownNonZero(X, TD, Depth); + return isKnownNonZero(X, TD, Depth, Q); bool XKnownNonNegative, XKnownNegative; - ComputeSignBit(X, XKnownNonNegative, XKnownNegative, TD, Depth); + ComputeSignBit(X, XKnownNonNegative, XKnownNegative, TD, Depth, Q); if (XKnownNegative) return true; } // div exact can only produce a zero if the dividend is zero. else if (match(V, m_Exact(m_IDiv(m_Value(X), m_Value())))) { - return isKnownNonZero(X, TD, Depth); + return isKnownNonZero(X, TD, Depth, Q); } // X + Y. else if (match(V, m_Add(m_Value(X), m_Value(Y)))) { bool XKnownNonNegative, XKnownNegative; bool YKnownNonNegative, YKnownNegative; - ComputeSignBit(X, XKnownNonNegative, XKnownNegative, TD, Depth); - ComputeSignBit(Y, YKnownNonNegative, YKnownNegative, TD, Depth); + ComputeSignBit(X, XKnownNonNegative, XKnownNegative, TD, Depth, Q); + ComputeSignBit(Y, YKnownNonNegative, YKnownNegative, TD, Depth, Q); // If X and Y are both non-negative (as signed values) then their sum is not // zero unless both X and Y are zero. if (XKnownNonNegative && YKnownNonNegative) - if (isKnownNonZero(X, TD, Depth) || isKnownNonZero(Y, TD, Depth)) + if (isKnownNonZero(X, TD, Depth, Q) || + isKnownNonZero(Y, TD, Depth, Q)) return true; // If X and Y are both negative (as signed values) then their sum is not @@ -937,20 +1626,22 @@ bool llvm::isKnownNonZero(Value *V, const TargetData *TD, unsigned Depth) { APInt Mask = APInt::getSignedMaxValue(BitWidth); // The sign bit of X is set. If some other bit is set then X is not equal // to INT_MIN. - ComputeMaskedBits(X, KnownZero, KnownOne, TD, Depth); + computeKnownBits(X, KnownZero, KnownOne, TD, Depth, Q); if ((KnownOne & Mask) != 0) return true; // The sign bit of Y is set. If some other bit is set then Y is not equal // to INT_MIN. - ComputeMaskedBits(Y, KnownZero, KnownOne, TD, Depth); + computeKnownBits(Y, KnownZero, KnownOne, TD, Depth, Q); if ((KnownOne & Mask) != 0) return true; } // The sum of a non-negative number and a power of two is not zero. - if (XKnownNonNegative && isPowerOfTwo(Y, TD, /*OrZero*/false, Depth)) + if (XKnownNonNegative && + isKnownToBeAPowerOfTwo(Y, /*OrZero*/false, Depth, Q)) return true; - if (YKnownNonNegative && isPowerOfTwo(X, TD, /*OrZero*/false, Depth)) + if (YKnownNonNegative && + isKnownToBeAPowerOfTwo(X, /*OrZero*/false, Depth, Q)) return true; } // X * Y. @@ -959,54 +1650,55 @@ bool llvm::isKnownNonZero(Value *V, const TargetData *TD, unsigned Depth) { // If X and Y are non-zero then so is X * Y as long as the multiplication // does not overflow. if ((BO->hasNoSignedWrap() || BO->hasNoUnsignedWrap()) && - isKnownNonZero(X, TD, Depth) && isKnownNonZero(Y, TD, Depth)) + isKnownNonZero(X, TD, Depth, Q) && + isKnownNonZero(Y, TD, Depth, Q)) return true; } // (C ? X : Y) != 0 if X != 0 and Y != 0. else if (SelectInst *SI = dyn_cast(V)) { - if (isKnownNonZero(SI->getTrueValue(), TD, Depth) && - isKnownNonZero(SI->getFalseValue(), TD, Depth)) + if (isKnownNonZero(SI->getTrueValue(), TD, Depth, Q) && + isKnownNonZero(SI->getFalseValue(), TD, Depth, Q)) return true; } if (!BitWidth) return false; APInt KnownZero(BitWidth, 0); APInt KnownOne(BitWidth, 0); - ComputeMaskedBits(V, KnownZero, KnownOne, TD, Depth); + computeKnownBits(V, KnownZero, KnownOne, TD, Depth, Q); return KnownOne != 0; } -/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use -/// this predicate to simplify operations downstream. Mask is known to be zero -/// for bits that V cannot have. +/// Return true if 'V & Mask' is known to be zero. We use this predicate to +/// simplify operations downstream. Mask is known to be zero for bits that V +/// cannot have. /// /// This function is defined on values with integer type, values with pointer /// type (but only if TD is non-null), and vectors of integers. In the case /// where V is a vector, the mask, known zero, and known one values are the /// same width as the vector element, and the bit is set only if it is true /// for all of the elements in the vector. -bool llvm::MaskedValueIsZero(Value *V, const APInt &Mask, - const TargetData *TD, unsigned Depth) { +bool MaskedValueIsZero(Value *V, const APInt &Mask, + const DataLayout *TD, unsigned Depth, + const Query &Q) { APInt KnownZero(Mask.getBitWidth(), 0), KnownOne(Mask.getBitWidth(), 0); - ComputeMaskedBits(V, KnownZero, KnownOne, TD, Depth); - assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); + computeKnownBits(V, KnownZero, KnownOne, TD, Depth, Q); return (KnownZero & Mask) == Mask; } -/// ComputeNumSignBits - Return the number of times the sign bit of the -/// register is replicated into the other bits. We know that at least 1 bit -/// is always equal to the sign bit (itself), but other cases can give us -/// information. For example, immediately after an "ashr X, 2", we know that -/// the top 3 bits are all equal to each other, so we return 3. +/// Return the number of times the sign bit of the register is replicated into +/// the other bits. We know that at least 1 bit is always equal to the sign bit +/// (itself), but other cases can give us information. For example, immediately +/// after an "ashr X, 2", we know that the top 3 bits are all equal to each +/// other, so we return 3. /// /// 'Op' must have a scalar integer type. /// -unsigned llvm::ComputeNumSignBits(Value *V, const TargetData *TD, - unsigned Depth) { +unsigned ComputeNumSignBits(Value *V, const DataLayout *TD, + unsigned Depth, const Query &Q) { assert((TD || V->getType()->isIntOrIntVectorTy()) && - "ComputeNumSignBits requires a TargetData object to operate " + "ComputeNumSignBits requires a DataLayout object to operate " "on non-integer values!"); Type *Ty = V->getType(); unsigned TyBits = TD ? TD->getTypeSizeInBits(V->getType()->getScalarType()) : @@ -1014,21 +1706,21 @@ unsigned llvm::ComputeNumSignBits(Value *V, const TargetData *TD, unsigned Tmp, Tmp2; unsigned FirstAnswer = 1; - // Note that ConstantInt is handled by the general ComputeMaskedBits case + // Note that ConstantInt is handled by the general computeKnownBits case // below. if (Depth == 6) return 1; // Limit search depth. - + Operator *U = dyn_cast(V); switch (Operator::getOpcode(V)) { default: break; case Instruction::SExt: Tmp = TyBits - U->getOperand(0)->getType()->getScalarSizeInBits(); - return ComputeNumSignBits(U->getOperand(0), TD, Depth+1) + Tmp; - + return ComputeNumSignBits(U->getOperand(0), TD, Depth+1, Q) + Tmp; + case Instruction::AShr: { - Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); + Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1, Q); // ashr X, C -> adds C sign bits. Vectors too. const APInt *ShAmt; if (match(U->getOperand(1), m_APInt(ShAmt))) { @@ -1041,7 +1733,7 @@ unsigned llvm::ComputeNumSignBits(Value *V, const TargetData *TD, const APInt *ShAmt; if (match(U->getOperand(1), m_APInt(ShAmt))) { // shl destroys sign bits. - Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); + Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1, Q); Tmp2 = ShAmt->getZExtValue(); if (Tmp2 >= TyBits || // Bad shift. Tmp2 >= Tmp) break; // Shifted all sign bits out. @@ -1053,89 +1745,90 @@ unsigned llvm::ComputeNumSignBits(Value *V, const TargetData *TD, case Instruction::Or: case Instruction::Xor: // NOT is handled here. // Logical binary ops preserve the number of sign bits at the worst. - Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); + Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1, Q); if (Tmp != 1) { - Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); + Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1, Q); FirstAnswer = std::min(Tmp, Tmp2); // We computed what we know about the sign bits as our first // answer. Now proceed to the generic code that uses - // ComputeMaskedBits, and pick whichever answer is better. + // computeKnownBits, and pick whichever answer is better. } break; case Instruction::Select: - Tmp = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); + Tmp = ComputeNumSignBits(U->getOperand(1), TD, Depth+1, Q); if (Tmp == 1) return 1; // Early out. - Tmp2 = ComputeNumSignBits(U->getOperand(2), TD, Depth+1); + Tmp2 = ComputeNumSignBits(U->getOperand(2), TD, Depth+1, Q); return std::min(Tmp, Tmp2); - + case Instruction::Add: // Add can have at most one carry bit. Thus we know that the output // is, at worst, one more bit than the inputs. - Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); + Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1, Q); if (Tmp == 1) return 1; // Early out. - + // Special case decrementing a value (ADD X, -1): if (ConstantInt *CRHS = dyn_cast(U->getOperand(1))) if (CRHS->isAllOnesValue()) { APInt KnownZero(TyBits, 0), KnownOne(TyBits, 0); - ComputeMaskedBits(U->getOperand(0), KnownZero, KnownOne, TD, Depth+1); - + computeKnownBits(U->getOperand(0), KnownZero, KnownOne, TD, Depth+1, Q); + // If the input is known to be 0 or 1, the output is 0/-1, which is all // sign bits set. if ((KnownZero | APInt(TyBits, 1)).isAllOnesValue()) return TyBits; - + // If we are subtracting one from a positive number, there is no carry // out of the result. if (KnownZero.isNegative()) return Tmp; } - - Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); + + Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1, Q); if (Tmp2 == 1) return 1; return std::min(Tmp, Tmp2)-1; - + case Instruction::Sub: - Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1); + Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1, Q); if (Tmp2 == 1) return 1; - + // Handle NEG. if (ConstantInt *CLHS = dyn_cast(U->getOperand(0))) if (CLHS->isNullValue()) { APInt KnownZero(TyBits, 0), KnownOne(TyBits, 0); - ComputeMaskedBits(U->getOperand(1), KnownZero, KnownOne, TD, Depth+1); + computeKnownBits(U->getOperand(1), KnownZero, KnownOne, TD, Depth+1, Q); // If the input is known to be 0 or 1, the output is 0/-1, which is all // sign bits set. if ((KnownZero | APInt(TyBits, 1)).isAllOnesValue()) return TyBits; - + // If the input is known to be positive (the sign bit is known clear), // the output of the NEG has the same number of sign bits as the input. if (KnownZero.isNegative()) return Tmp2; - + // Otherwise, we treat this like a SUB. } - + // Sub can have at most one carry bit. Thus we know that the output // is, at worst, one more bit than the inputs. - Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1); + Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1, Q); if (Tmp == 1) return 1; // Early out. return std::min(Tmp, Tmp2)-1; - + case Instruction::PHI: { PHINode *PN = cast(U); // Don't analyze large in-degree PHIs. if (PN->getNumIncomingValues() > 4) break; - + // Take the minimum of all incoming values. This can't infinitely loop // because of our depth threshold. - Tmp = ComputeNumSignBits(PN->getIncomingValue(0), TD, Depth+1); + Tmp = ComputeNumSignBits(PN->getIncomingValue(0), TD, Depth+1, Q); for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) { if (Tmp == 1) return Tmp; Tmp = std::min(Tmp, - ComputeNumSignBits(PN->getIncomingValue(i), TD, Depth+1)); + ComputeNumSignBits(PN->getIncomingValue(i), TD, + Depth+1, Q)); } return Tmp; } @@ -1145,13 +1838,13 @@ unsigned llvm::ComputeNumSignBits(Value *V, const TargetData *TD, // case for targets like X86. break; } - + // Finally, if we can prove that the top bits of the result are 0's or 1's, // use this information. APInt KnownZero(TyBits, 0), KnownOne(TyBits, 0); APInt Mask; - ComputeMaskedBits(V, KnownZero, KnownOne, TD, Depth); - + computeKnownBits(V, KnownZero, KnownOne, TD, Depth, Q); + if (KnownZero.isNegative()) { // sign bit is 0 Mask = KnownZero; } else if (KnownOne.isNegative()) { // sign bit is 1; @@ -1160,7 +1853,7 @@ unsigned llvm::ComputeNumSignBits(Value *V, const TargetData *TD, // Nothing known. return FirstAnswer; } - + // Okay, we know that the sign bit in Mask is set. Use CLZ to determine // the number of identical bits in the top of the input value. Mask = ~Mask; @@ -1170,9 +1863,9 @@ unsigned llvm::ComputeNumSignBits(Value *V, const TargetData *TD, return std::max(FirstAnswer, std::min(TyBits, Mask.countLeadingZeros())); } -/// ComputeMultiple - This function computes the integer multiple of Base that -/// equals V. If successful, it returns true and returns the multiple in -/// Multiple. If unsuccessful, it returns false. It looks +/// This function computes the integer multiple of Base that equals V. +/// If successful, it returns true and returns the multiple in +/// Multiple. If unsuccessful, it returns false. It looks /// through SExt instructions only if LookThroughSExt is true. bool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple, bool LookThroughSExt, unsigned Depth) { @@ -1188,7 +1881,7 @@ bool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple, if (Base == 0) return false; - + if (Base == 1) { Multiple = V; return true; @@ -1204,11 +1897,11 @@ bool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple, if (CI && CI->getZExtValue() % Base == 0) { Multiple = ConstantInt::get(T, CI->getZExtValue() / Base); - return true; + return true; } - + if (Depth == MaxDepth) return false; // Limit search depth. - + Operator *I = dyn_cast(V); if (!I) return false; @@ -1236,17 +1929,17 @@ bool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple, Op1 = ConstantInt::get(V->getContext(), API); } - Value *Mul0 = NULL; + Value *Mul0 = nullptr; if (ComputeMultiple(Op0, Base, Mul0, LookThroughSExt, Depth+1)) { if (Constant *Op1C = dyn_cast(Op1)) if (Constant *MulC = dyn_cast(Mul0)) { - if (Op1C->getType()->getPrimitiveSizeInBits() < + if (Op1C->getType()->getPrimitiveSizeInBits() < MulC->getType()->getPrimitiveSizeInBits()) Op1C = ConstantExpr::getZExt(Op1C, MulC->getType()); - if (Op1C->getType()->getPrimitiveSizeInBits() > + if (Op1C->getType()->getPrimitiveSizeInBits() > MulC->getType()->getPrimitiveSizeInBits()) MulC = ConstantExpr::getZExt(MulC, Op1C->getType()); - + // V == Base * (Mul0 * Op1), so return (Mul0 * Op1) Multiple = ConstantExpr::getMul(MulC, Op1C); return true; @@ -1260,17 +1953,17 @@ bool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple, } } - Value *Mul1 = NULL; + Value *Mul1 = nullptr; if (ComputeMultiple(Op1, Base, Mul1, LookThroughSExt, Depth+1)) { if (Constant *Op0C = dyn_cast(Op0)) if (Constant *MulC = dyn_cast(Mul1)) { - if (Op0C->getType()->getPrimitiveSizeInBits() < + if (Op0C->getType()->getPrimitiveSizeInBits() < MulC->getType()->getPrimitiveSizeInBits()) Op0C = ConstantExpr::getZExt(Op0C, MulC->getType()); - if (Op0C->getType()->getPrimitiveSizeInBits() > + if (Op0C->getType()->getPrimitiveSizeInBits() > MulC->getType()->getPrimitiveSizeInBits()) MulC = ConstantExpr::getZExt(MulC, Op0C->getType()); - + // V == Base * (Mul1 * Op0), so return (Mul1 * Op0) Multiple = ConstantExpr::getMul(MulC, Op0C); return true; @@ -1290,8 +1983,8 @@ bool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple, return false; } -/// CannotBeNegativeZero - Return true if we can prove that the specified FP -/// value is never equal to -0.0. +/// Return true if we can prove that the specified FP value is never equal to +/// -0.0. /// /// NOTE: this function will need to be revisited when we support non-default /// rounding modes! @@ -1299,28 +1992,33 @@ bool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple, bool llvm::CannotBeNegativeZero(const Value *V, unsigned Depth) { if (const ConstantFP *CFP = dyn_cast(V)) return !CFP->getValueAPF().isNegZero(); - + if (Depth == 6) return 1; // Limit search depth. const Operator *I = dyn_cast(V); - if (I == 0) return false; - + if (!I) return false; + + // Check if the nsz fast-math flag is set + if (const FPMathOperator *FPO = dyn_cast(I)) + if (FPO->hasNoSignedZeros()) + return true; + // (add x, 0.0) is guaranteed to return +0.0, not -0.0. - if (I->getOpcode() == Instruction::FAdd && - isa(I->getOperand(1)) && - cast(I->getOperand(1))->isNullValue()) - return true; - + if (I->getOpcode() == Instruction::FAdd) + if (ConstantFP *CFP = dyn_cast(I->getOperand(1))) + if (CFP->isNullValue()) + return true; + // sitofp and uitofp turn into +0.0 for zero. if (isa(I) || isa(I)) return true; - + if (const IntrinsicInst *II = dyn_cast(I)) // sqrt(-0.0) = -0.0, no other negative results are possible. if (II->getIntrinsicID() == Intrinsic::sqrt) return CannotBeNegativeZero(II->getArgOperand(0), Depth+1); - + if (const CallInst *CI = dyn_cast(I)) if (const Function *F = CI->getCalledFunction()) { if (F->isDeclaration()) { @@ -1335,12 +2033,12 @@ bool llvm::CannotBeNegativeZero(const Value *V, unsigned Depth) { return CannotBeNegativeZero(CI->getArgOperand(0), Depth+1); } } - + return false; } -/// isBytewiseValue - If the specified value can be set by repeating the same -/// byte in memory, return the i8 value that it is represented with. This is +/// If the specified value can be set by repeating the same byte in memory, +/// return the i8 value that it is represented with. This is /// true for all i8 values obviously, but is also true for i32 0, i32 -1, /// i16 0xF0F0, double 0.0 etc. If the value can't be handled with a repeated /// byte store (e.g. i16 0x1234), return null. @@ -1352,9 +2050,9 @@ Value *llvm::isBytewiseValue(Value *V) { if (Constant *C = dyn_cast(V)) if (C->isNullValue()) return Constant::getNullValue(Type::getInt8Ty(V->getContext())); - + // Constant float and double values can be handled as integer values if the - // corresponding integer value is "byteable". An important case is 0.0. + // corresponding integer value is "byteable". An important case is 0.0. if (ConstantFP *CFP = dyn_cast(V)) { if (CFP->getType()->isFloatTy()) V = ConstantExpr::getBitCast(CFP, Type::getInt32Ty(V->getContext())); @@ -1362,8 +2060,8 @@ Value *llvm::isBytewiseValue(Value *V) { V = ConstantExpr::getBitCast(CFP, Type::getInt64Ty(V->getContext())); // Don't handle long double formats, which have strange constraints. } - - // We can handle constant integers that are power of two in size and a + + // We can handle constant integers that are power of two in size and a // multiple of 8 bits. if (ConstantInt *CI = dyn_cast(V)) { unsigned Width = CI->getBitWidth(); @@ -1377,27 +2075,27 @@ Value *llvm::isBytewiseValue(Value *V) { Val2 = Val.lshr(NextWidth); Val2 = Val2.trunc(Val.getBitWidth()/2); Val = Val.trunc(Val.getBitWidth()/2); - + // If the top/bottom halves aren't the same, reject it. if (Val != Val2) - return 0; + return nullptr; } return ConstantInt::get(V->getContext(), Val); } } - + // A ConstantDataArray/Vector is splatable if all its members are equal and // also splatable. if (ConstantDataSequential *CA = dyn_cast(V)) { Value *Elt = CA->getElementAsConstant(0); Value *Val = isBytewiseValue(Elt); if (!Val) - return 0; - + return nullptr; + for (unsigned I = 1, E = CA->getNumElements(); I != E; ++I) if (CA->getElementAsConstant(I) != Elt) - return 0; - + return nullptr; + return Val; } @@ -1407,7 +2105,7 @@ Value *llvm::isBytewiseValue(Value *V) { // %c = or i16 %a, %b // but until there is an example that actually needs this, it doesn't seem // worth worrying about. - return 0; + return nullptr; } @@ -1418,10 +2116,10 @@ Value *llvm::isBytewiseValue(Value *V) { // struct. To is the result struct built so far, new insertvalue instructions // build on that. static Value *BuildSubAggregate(Value *From, Value* To, Type *IndexedType, - SmallVector &Idxs, + SmallVectorImpl &Idxs, unsigned IdxSkip, Instruction *InsertBefore) { - llvm::StructType *STy = llvm::dyn_cast(IndexedType); + llvm::StructType *STy = dyn_cast(IndexedType); if (STy) { // Save the original To argument so we can modify it Value *OrigTo = To; @@ -1452,12 +2150,12 @@ static Value *BuildSubAggregate(Value *From, Value* To, Type *IndexedType, // the struct's elements had a value that was inserted directly. In the latter // case, perhaps we can't determine each of the subelements individually, but // we might be able to find the complete struct somewhere. - + // Find the value that is at that particular spot Value *V = FindInsertedValue(From, Idxs); if (!V) - return NULL; + return nullptr; // Insert the value in the new (sub) aggregrate return llvm::InsertValueInst::Create(To, V, makeArrayRef(Idxs).slice(IdxSkip), @@ -1488,7 +2186,7 @@ static Value *BuildSubAggregate(Value *From, ArrayRef idx_range, return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip, InsertBefore); } -/// FindInsertedValue - Given an aggregrate and an sequence of indices, see if +/// Given an aggregrate and an sequence of indices, see if /// the scalar value indexed is already around as a register, for example if it /// were inserted directly into the aggregrate. /// @@ -1508,10 +2206,10 @@ Value *llvm::FindInsertedValue(Value *V, ArrayRef idx_range, if (Constant *C = dyn_cast(V)) { C = C->getAggregateElement(idx_range[0]); - if (C == 0) return 0; + if (!C) return nullptr; return FindInsertedValue(C, idx_range.slice(1), InsertBefore); } - + if (InsertValueInst *I = dyn_cast(V)) { // Loop the indices for the insertvalue instruction in parallel with the // requested indices @@ -1521,7 +2219,7 @@ Value *llvm::FindInsertedValue(Value *V, ArrayRef idx_range, if (req_idx == idx_range.end()) { // We can't handle this without inserting insertvalues if (!InsertBefore) - return 0; + return nullptr; // The requested index identifies a part of a nested aggregate. Handle // this specially. For example, @@ -1536,7 +2234,7 @@ Value *llvm::FindInsertedValue(Value *V, ArrayRef idx_range, return BuildSubAggregate(V, makeArrayRef(idx_range.begin(), req_idx), InsertBefore); } - + // This insert value inserts something else than what we are looking for. // See if the (aggregrate) value inserted into has the value we are // looking for, then. @@ -1551,104 +2249,100 @@ Value *llvm::FindInsertedValue(Value *V, ArrayRef idx_range, makeArrayRef(req_idx, idx_range.end()), InsertBefore); } - + if (ExtractValueInst *I = dyn_cast(V)) { // If we're extracting a value from an aggregrate that was extracted from // something else, we can extract from that something else directly instead. // However, we will need to chain I's indices with the requested indices. - - // Calculate the number of indices required + + // Calculate the number of indices required unsigned size = I->getNumIndices() + idx_range.size(); // Allocate some space to put the new indices in SmallVector Idxs; Idxs.reserve(size); // Add indices from the extract value instruction Idxs.append(I->idx_begin(), I->idx_end()); - + // Add requested indices Idxs.append(idx_range.begin(), idx_range.end()); - assert(Idxs.size() == size + assert(Idxs.size() == size && "Number of indices added not correct?"); - + return FindInsertedValue(I->getAggregateOperand(), Idxs, InsertBefore); } // Otherwise, we don't know (such as, extracting from a function return value // or load instruction) - return 0; + return nullptr; } -/// GetPointerBaseWithConstantOffset - Analyze the specified pointer to see if -/// it can be expressed as a base pointer plus a constant offset. Return the -/// base and offset to the caller. +/// Analyze the specified pointer to see if it can be expressed as a base +/// pointer plus a constant offset. Return the base and offset to the caller. Value *llvm::GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset, - const TargetData &TD) { - Operator *PtrOp = dyn_cast(Ptr); - if (PtrOp == 0 || Ptr->getType()->isVectorTy()) - return Ptr; - - // Just look through bitcasts. - if (PtrOp->getOpcode() == Instruction::BitCast) - return GetPointerBaseWithConstantOffset(PtrOp->getOperand(0), Offset, TD); - - // If this is a GEP with constant indices, we can look through it. - GEPOperator *GEP = dyn_cast(PtrOp); - if (GEP == 0 || !GEP->hasAllConstantIndices()) return Ptr; - - gep_type_iterator GTI = gep_type_begin(GEP); - for (User::op_iterator I = GEP->idx_begin(), E = GEP->idx_end(); I != E; - ++I, ++GTI) { - ConstantInt *OpC = cast(*I); - if (OpC->isZero()) continue; - - // Handle a struct and array indices which add their offset to the pointer. - if (StructType *STy = dyn_cast(*GTI)) { - Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue()); + const DataLayout *DL) { + // Without DataLayout, conservatively assume 64-bit offsets, which is + // the widest we support. + unsigned BitWidth = DL ? DL->getPointerTypeSizeInBits(Ptr->getType()) : 64; + APInt ByteOffset(BitWidth, 0); + while (1) { + if (Ptr->getType()->isVectorTy()) + break; + + if (GEPOperator *GEP = dyn_cast(Ptr)) { + if (DL) { + APInt GEPOffset(BitWidth, 0); + if (!GEP->accumulateConstantOffset(*DL, GEPOffset)) + break; + + ByteOffset += GEPOffset; + } + + Ptr = GEP->getPointerOperand(); + } else if (Operator::getOpcode(Ptr) == Instruction::BitCast || + Operator::getOpcode(Ptr) == Instruction::AddrSpaceCast) { + Ptr = cast(Ptr)->getOperand(0); + } else if (GlobalAlias *GA = dyn_cast(Ptr)) { + if (GA->mayBeOverridden()) + break; + Ptr = GA->getAliasee(); } else { - uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()); - Offset += OpC->getSExtValue()*Size; + break; } } - - // Re-sign extend from the pointer size if needed to get overflow edge cases - // right. - unsigned PtrSize = TD.getPointerSizeInBits(); - if (PtrSize < 64) - Offset = (Offset << (64-PtrSize)) >> (64-PtrSize); - - return GetPointerBaseWithConstantOffset(GEP->getPointerOperand(), Offset, TD); + Offset = ByteOffset.getSExtValue(); + return Ptr; } -/// getConstantStringInfo - This function computes the length of a -/// null-terminated C string pointed to by V. If successful, it returns true -/// and returns the string in Str. If unsuccessful, it returns false. +/// This function computes the length of a null-terminated C string pointed to +/// by V. If successful, it returns true and returns the string in Str. +/// If unsuccessful, it returns false. bool llvm::getConstantStringInfo(const Value *V, StringRef &Str, uint64_t Offset, bool TrimAtNul) { assert(V); // Look through bitcast instructions and geps. V = V->stripPointerCasts(); - + // If the value is a GEP instructionor constant expression, treat it as an // offset. if (const GEPOperator *GEP = dyn_cast(V)) { // Make sure the GEP has exactly three arguments. if (GEP->getNumOperands() != 3) return false; - + // Make sure the index-ee is a pointer to array of i8. PointerType *PT = cast(GEP->getOperand(0)->getType()); ArrayType *AT = dyn_cast(PT->getElementType()); - if (AT == 0 || !AT->getElementType()->isIntegerTy(8)) + if (!AT || !AT->getElementType()->isIntegerTy(8)) return false; - + // Check to make sure that the first operand of the GEP is an integer and // has value 0 so that we are sure we're indexing into the initializer. const ConstantInt *FirstIdx = dyn_cast(GEP->getOperand(1)); - if (FirstIdx == 0 || !FirstIdx->isZero()) + if (!FirstIdx || !FirstIdx->isZero()) return false; - + // If the second index isn't a ConstantInt, then this is a variable index // into the array. If this occurs, we can't say anything meaningful about // the string. @@ -1674,13 +2368,13 @@ bool llvm::getConstantStringInfo(const Value *V, StringRef &Str, Str = ""; return true; } - + // Must be a Constant Array const ConstantDataArray *Array = dyn_cast(GV->getInitializer()); - if (Array == 0 || !Array->isString()) + if (!Array || !Array->isString()) return false; - + // Get the number of elements in the array uint64_t NumElts = Array->getType()->getArrayNumElements(); @@ -1689,10 +2383,10 @@ bool llvm::getConstantStringInfo(const Value *V, StringRef &Str, if (Offset > NumElts) return false; - + // Skip over 'offset' bytes. Str = Str.substr(Offset); - + if (TrimAtNul) { // Trim off the \0 and anything after it. If the array is not nul // terminated, we just return the whole end of string. The client may know @@ -1706,16 +2400,16 @@ bool llvm::getConstantStringInfo(const Value *V, StringRef &Str, // nodes. // TODO: See if we can integrate these two together. -/// GetStringLengthH - If we can compute the length of the string pointed to by +/// If we can compute the length of the string pointed to by /// the specified pointer, return 'len+1'. If we can't, return 0. -static uint64_t GetStringLengthH(Value *V, SmallPtrSet &PHIs) { +static uint64_t GetStringLengthH(Value *V, SmallPtrSetImpl &PHIs) { // Look through noop bitcast instructions. V = V->stripPointerCasts(); // If this is a PHI node, there are two cases: either we have already seen it // or we haven't. if (PHINode *PN = dyn_cast(V)) { - if (!PHIs.insert(PN)) + if (!PHIs.insert(PN).second) return ~0ULL; // already in the set. // If it was new, see if all the input strings are the same length. @@ -1746,7 +2440,7 @@ static uint64_t GetStringLengthH(Value *V, SmallPtrSet &PHIs) { if (Len1 != Len2) return 0; return Len1; } - + // Otherwise, see if we can read the string. StringRef StrData; if (!getConstantStringInfo(V, StrData)) @@ -1755,7 +2449,7 @@ static uint64_t GetStringLengthH(Value *V, SmallPtrSet &PHIs) { return StrData.size()+1; } -/// GetStringLength - If we can compute the length of the string pointed to by +/// If we can compute the length of the string pointed to by /// the specified pointer, return 'len+1'. If we can't, return 0. uint64_t llvm::GetStringLength(Value *V) { if (!V->getType()->isPointerTy()) return 0; @@ -1768,13 +2462,14 @@ uint64_t llvm::GetStringLength(Value *V) { } Value * -llvm::GetUnderlyingObject(Value *V, const TargetData *TD, unsigned MaxLookup) { +llvm::GetUnderlyingObject(Value *V, const DataLayout *TD, unsigned MaxLookup) { if (!V->getType()->isPointerTy()) return V; for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) { if (GEPOperator *GEP = dyn_cast(V)) { V = GEP->getPointerOperand(); - } else if (Operator::getOpcode(V) == Instruction::BitCast) { + } else if (Operator::getOpcode(V) == Instruction::BitCast || + Operator::getOpcode(V) == Instruction::AddrSpaceCast) { V = cast(V)->getOperand(0); } else if (GlobalAlias *GA = dyn_cast(V)) { if (GA->mayBeOverridden()) @@ -1783,8 +2478,8 @@ llvm::GetUnderlyingObject(Value *V, const TargetData *TD, unsigned MaxLookup) { } else { // See if InstructionSimplify knows any relevant tricks. if (Instruction *I = dyn_cast(V)) - // TODO: Acquire a DominatorTree and use it. - if (Value *Simplified = SimplifyInstruction(I, TD, 0)) { + // TODO: Acquire a DominatorTree and AssumptionTracker and use them. + if (Value *Simplified = SimplifyInstruction(I, TD, nullptr)) { V = Simplified; continue; } @@ -1799,7 +2494,7 @@ llvm::GetUnderlyingObject(Value *V, const TargetData *TD, unsigned MaxLookup) { void llvm::GetUnderlyingObjects(Value *V, SmallVectorImpl &Objects, - const TargetData *TD, + const DataLayout *TD, unsigned MaxLookup) { SmallPtrSet Visited; SmallVector Worklist; @@ -1808,7 +2503,7 @@ llvm::GetUnderlyingObjects(Value *V, Value *P = Worklist.pop_back_val(); P = GetUnderlyingObject(P, TD, MaxLookup); - if (!Visited.insert(P)) + if (!Visited.insert(P).second) continue; if (SelectInst *SI = dyn_cast(P)) { @@ -1827,13 +2522,10 @@ llvm::GetUnderlyingObjects(Value *V, } while (!Worklist.empty()); } -/// onlyUsedByLifetimeMarkers - Return true if the only users of this pointer -/// are lifetime markers. -/// +/// Return true if the only users of this pointer are lifetime markers. bool llvm::onlyUsedByLifetimeMarkers(const Value *V) { - for (Value::const_use_iterator UI = V->use_begin(), UE = V->use_end(); - UI != UE; ++UI) { - const IntrinsicInst *II = dyn_cast(*UI); + for (const User *U : V->users()) { + const IntrinsicInst *II = dyn_cast(U); if (!II) return false; if (II->getIntrinsicID() != Intrinsic::lifetime_start && @@ -1844,7 +2536,7 @@ bool llvm::onlyUsedByLifetimeMarkers(const Value *V) { } bool llvm::isSafeToSpeculativelyExecute(const Value *V, - const TargetData *TD) { + const DataLayout *TD) { const Operator *Inst = dyn_cast(V); if (!Inst) return false; @@ -1858,60 +2550,79 @@ bool llvm::isSafeToSpeculativelyExecute(const Value *V, default: return true; case Instruction::UDiv: - case Instruction::URem: - // x / y is undefined if y == 0, but calcuations like x / 3 are safe. - return isKnownNonZero(Inst->getOperand(1), TD); + case Instruction::URem: { + // x / y is undefined if y == 0. + const APInt *V; + if (match(Inst->getOperand(1), m_APInt(V))) + return *V != 0; + return false; + } case Instruction::SDiv: case Instruction::SRem: { - Value *Op = Inst->getOperand(1); - // x / y is undefined if y == 0 - if (!isKnownNonZero(Op, TD)) - return false; - // x / y might be undefined if y == -1 - unsigned BitWidth = getBitWidth(Op->getType(), TD); - if (BitWidth == 0) - return false; - APInt KnownZero(BitWidth, 0); - APInt KnownOne(BitWidth, 0); - ComputeMaskedBits(Op, KnownZero, KnownOne, TD); - return !!KnownZero; + // x / y is undefined if y == 0 or x == INT_MIN and y == -1 + const APInt *X, *Y; + if (match(Inst->getOperand(1), m_APInt(Y))) { + if (*Y != 0) { + if (*Y == -1) { + // The numerator can't be MinSignedValue if the denominator is -1. + if (match(Inst->getOperand(0), m_APInt(X))) + return !Y->isMinSignedValue(); + // The numerator *might* be MinSignedValue. + return false; + } + // The denominator is not 0 or -1, it's safe to proceed. + return true; + } + } + return false; } case Instruction::Load: { const LoadInst *LI = cast(Inst); - if (!LI->isUnordered()) + if (!LI->isUnordered() || + // Speculative load may create a race that did not exist in the source. + LI->getParent()->getParent()->hasFnAttribute(Attribute::SanitizeThread)) return false; - return LI->getPointerOperand()->isDereferenceablePointer(); + return LI->getPointerOperand()->isDereferenceablePointer(TD); } case Instruction::Call: { - if (const IntrinsicInst *II = dyn_cast(Inst)) { - switch (II->getIntrinsicID()) { - // These synthetic intrinsics have no side-effects, and just mark - // information about their operands. - // FIXME: There are other no-op synthetic instructions that potentially - // should be considered at least *safe* to speculate... - case Intrinsic::dbg_declare: - case Intrinsic::dbg_value: - return true; - - case Intrinsic::bswap: - case Intrinsic::ctlz: - case Intrinsic::ctpop: - case Intrinsic::cttz: - case Intrinsic::objectsize: - case Intrinsic::sadd_with_overflow: - case Intrinsic::smul_with_overflow: - case Intrinsic::ssub_with_overflow: - case Intrinsic::uadd_with_overflow: - case Intrinsic::umul_with_overflow: - case Intrinsic::usub_with_overflow: - return true; - // TODO: some fp intrinsics are marked as having the same error handling - // as libm. They're safe to speculate when they won't error. - // TODO: are convert_{from,to}_fp16 safe? - // TODO: can we list target-specific intrinsics here? - default: break; - } - } + if (const IntrinsicInst *II = dyn_cast(Inst)) { + switch (II->getIntrinsicID()) { + // These synthetic intrinsics have no side-effects and just mark + // information about their operands. + // FIXME: There are other no-op synthetic instructions that potentially + // should be considered at least *safe* to speculate... + case Intrinsic::dbg_declare: + case Intrinsic::dbg_value: + return true; + + case Intrinsic::bswap: + case Intrinsic::ctlz: + case Intrinsic::ctpop: + case Intrinsic::cttz: + case Intrinsic::objectsize: + case Intrinsic::sadd_with_overflow: + case Intrinsic::smul_with_overflow: + case Intrinsic::ssub_with_overflow: + case Intrinsic::uadd_with_overflow: + case Intrinsic::umul_with_overflow: + case Intrinsic::usub_with_overflow: + return true; + // Sqrt should be OK, since the llvm sqrt intrinsic isn't defined to set + // errno like libm sqrt would. + case Intrinsic::sqrt: + case Intrinsic::fma: + case Intrinsic::fmuladd: + case Intrinsic::fabs: + case Intrinsic::minnum: + case Intrinsic::maxnum: + return true; + // TODO: some fp intrinsics are marked as having the same error handling + // as libm. They're safe to speculate when they won't error. + // TODO: are convert_{from,to}_fp16 safe? + // TODO: can we list target-specific intrinsics here? + default: break; + } + } return false; // The called function could have undefined behavior or // side-effects, even if marked readnone nounwind. } @@ -1933,3 +2644,31 @@ bool llvm::isSafeToSpeculativelyExecute(const Value *V, return false; // Misc instructions which have effects } } + +/// Return true if we know that the specified value is never null. +bool llvm::isKnownNonNull(const Value *V, const TargetLibraryInfo *TLI) { + // Alloca never returns null, malloc might. + if (isa(V)) return true; + + // A byval, inalloca, or nonnull argument is never null. + if (const Argument *A = dyn_cast(V)) + return A->hasByValOrInAllocaAttr() || A->hasNonNullAttr(); + + // Global values are not null unless extern weak. + if (const GlobalValue *GV = dyn_cast(V)) + return !GV->hasExternalWeakLinkage(); + + // A Load tagged w/nonnull metadata is never null. + if (const LoadInst *LI = dyn_cast(V)) + return LI->getMetadata(LLVMContext::MD_nonnull); + + if (ImmutableCallSite CS = V) + if (CS.isReturnNonNull()) + return true; + + // operator new never returns null. + if (isOperatorNewLikeFn(V, TLI, /*LookThroughBitCast=*/true)) + return true; + + return false; +}