//===----------------------------------------------------------------------===//
#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Analysis/AssumptionTracker.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Analysis/InstructionSimplify.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/Metadata.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PatternMatch.h"
+#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include <cstring>
using namespace llvm;
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.
+/// 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;
return TD ? TD->getPointerTypeSizeInBits(Ty) : 0;
}
-static void ComputeMaskedBitsAddSub(bool Add, Value *Op0, Value *Op1, bool NSW,
- APInt &KnownZero, APInt &KnownOne,
- APInt &KnownZero2, APInt &KnownOne2,
- const DataLayout *TD, unsigned Depth) {
+// 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<const Value *, 8> 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<Instruction>(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 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<ConstantInt>(Op0)) {
// We know that the top bits of C-X are clear if X contains less bits
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
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 DataLayout *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;
// 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));
}
}
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);
// Use the high end of the ranges to find leading zeros.
unsigned MinLeadingZeros = BitWidth;
for (unsigned i = 0; i < NumRanges; ++i) {
- ConstantInt *Lower = cast<ConstantInt>(Ranges.getOperand(2*i + 0));
- ConstantInt *Upper = cast<ConstantInt>(Ranges.getOperand(2*i + 1));
+ ConstantInt *Lower =
+ mdconst::extract<ConstantInt>(Ranges.getOperand(2 * i + 0));
+ ConstantInt *Upper =
+ mdconst::extract<ConstantInt>(Ranges.getOperand(2 * i + 1));
ConstantRange Range(Lower->getValue(), Upper->getValue());
if (Range.isWrappedSet())
MinLeadingZeros = 0; // -1 has no zeros
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<const Value *, 16> WorkSet(1, I);
+ SmallPtrSet<const Value *, 32> Visited;
+ SmallPtrSet<const Value *, 16> 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<User>(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<CallInst>(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<Instruction>(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<Instruction*>(I),
+ Query(nullptr, CxtI, DT), DL);
+}
+
+template<typename LHS, typename RHS>
+inline match_combine_or<CmpClass_match<LHS, RHS, ICmpInst, ICmpInst::Predicate>,
+ CmpClass_match<RHS, LHS, ICmpInst, ICmpInst::Predicate>>
+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<typename LHS, typename RHS>
+inline match_combine_or<BinaryOp_match<LHS, RHS, Instruction::And>,
+ BinaryOp_match<RHS, LHS, Instruction::And>>
+m_c_And(const LHS &L, const RHS &R) {
+ return m_CombineOr(m_And(L, R), m_And(R, L));
+}
+
+template<typename LHS, typename RHS>
+inline match_combine_or<BinaryOp_match<LHS, RHS, Instruction::Or>,
+ BinaryOp_match<RHS, LHS, Instruction::Or>>
+m_c_Or(const LHS &L, const RHS &R) {
+ return m_CombineOr(m_Or(L, R), m_Or(R, L));
+}
+
+template<typename LHS, typename RHS>
+inline match_combine_or<BinaryOp_match<LHS, RHS, Instruction::Xor>,
+ BinaryOp_match<RHS, LHS, Instruction::Xor>>
+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<Function*>(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<IntrinsicInst>(I) &&
+ dyn_cast<IntrinsicInst>(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
/// 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 DataLayout *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();
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<ConstantInt>(V)) {
// We know all of the bits for a constant!
}
// The address of an aligned GlobalValue has trailing zeros.
- if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
- unsigned Align = GV->getAlignment();
+ if (auto *GO = dyn_cast<GlobalObject>(V)) {
+ unsigned Align = GO->getAlignment();
if (Align == 0 && TD) {
- if (GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) {
+ if (auto *GVar = dyn_cast<GlobalVariable>(GO)) {
Type *ObjectType = GVar->getType()->getElementType();
if (ObjectType->isSized()) {
// If the object is defined in the current Module, we'll be giving
KnownOne.clearAllBits();
return;
}
- // A weak GlobalAlias is totally unknown. A non-weak GlobalAlias has
- // the bits of its aliasee.
- if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
- if (GA->mayBeOverridden()) {
- KnownZero.clearAllBits(); KnownOne.clearAllBits();
- } else {
- ComputeMaskedBits(GA->getAliasee(), KnownZero, KnownOne, TD, Depth+1);
- }
- return;
- }
if (Argument *A = dyn_cast<Argument>(V)) {
- unsigned Align = 0;
+ unsigned Align = A->getType()->isPointerTy() ? A->getParamAlignment() : 0;
- if (A->hasByValOrInAllocaAttr()) {
- // Get alignment information off byval/inalloca arguments if specified in
- // the IR.
- Align = A->getParamAlignment();
- } else if (TD && A->hasStructRetAttr()) {
+ if (!Align && TD && A->hasStructRetAttr()) {
// An sret parameter has at least the ABI alignment of the return type.
Type *EltTy = cast<PointerType>(A->getType())->getElementType();
if (EltTy->isSized())
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<GlobalAlias>(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<Operator>(V);
if (!I) return;
default: break;
case Instruction::Load:
if (MDNode *MD = cast<LoadInst>(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<OverflowingBinaryOperator>(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: {
SrcBitWidth = TD->getTypeSizeInBits(SrcTy->getScalarType());
} else {
SrcBitWidth = SrcTy->getScalarSizeInBits();
- if (!SrcBitWidth) return;
+ 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();
// 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;
}
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);
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<ConstantInt>(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:
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:
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);
KnownZero |= HighBits;
else if (KnownOne[BitWidth-ShiftAmt-1]) // New bits are known one.
KnownOne |= HighBits;
- return;
}
break;
case Instruction::Sub: {
bool NSW = cast<OverflowingBinaryOperator>(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<OverflowingBinaryOperator>(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:
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;
// 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);
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;
// 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());
// 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);
Value *Index = I->getOperand(i);
if (StructType *STy = dyn_cast<StructType>(*GTI)) {
// Handle struct member offset arithmetic.
- if (!TD)
- return;
+ if (!TD) {
+ TrailZ = 0;
+ break;
+ }
// Handle case when index is vector zeroinitializer
Constant *CIndex = cast<Constant>(Index);
} 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(TypeSize) +
LocalKnownZero.countTrailingOnes()));
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(),
// 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.
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
break;
}
case Instruction::Call:
+ case Instruction::Invoke:
+ if (MDNode *MD = cast<Instruction>(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<IntrinsicInst>(I)) {
switch (II->getIntrinsicID()) {
default: break;
// 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_64:
- KnownZero = APInt::getHighBitsSet(64, 32);
+ KnownZero |= APInt::getHighBitsSet(64, 32);
break;
}
}
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 DataLayout *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;
}
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];
}
-/// isKnownToBeAPowerOfTwo - 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::isKnownToBeAPowerOfTwo(Value *V, bool OrZero, unsigned Depth) {
+bool isKnownToBeAPowerOfTwo(Value *V, bool OrZero, unsigned Depth,
+ const Query &Q) {
if (Constant *C = dyn_cast<Constant>(V)) {
if (C->isNullValue())
return 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 isKnownToBeAPowerOfTwo(X, /*OrZero*/true, Depth);
+ return isKnownToBeAPowerOfTwo(X, /*OrZero*/true, Depth, Q);
if (ZExtInst *ZI = dyn_cast<ZExtInst>(V))
- return isKnownToBeAPowerOfTwo(ZI->getOperand(0), OrZero, Depth);
+ return isKnownToBeAPowerOfTwo(ZI->getOperand(0), OrZero, Depth, Q);
if (SelectInst *SI = dyn_cast<SelectInst>(V))
- return isKnownToBeAPowerOfTwo(SI->getTrueValue(), OrZero, Depth) &&
- isKnownToBeAPowerOfTwo(SI->getFalseValue(), 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 (isKnownToBeAPowerOfTwo(X, /*OrZero*/true, Depth) ||
- isKnownToBeAPowerOfTwo(Y, /*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))))
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))
+ 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))
+ if (isKnownToBeAPowerOfTwo(X, OrZero, Depth, Q))
return true;
unsigned BitWidth = V->getType()->getScalarSizeInBits();
APInt LHSZeroBits(BitWidth, 0), LHSOneBits(BitWidth, 0);
- ComputeMaskedBits(X, LHSZeroBits, LHSOneBits, 0, Depth);
+ computeKnownBits(X, LHSZeroBits, LHSOneBits, nullptr, Depth, Q);
APInt RHSZeroBits(BitWidth, 0), RHSOneBits(BitWidth, 0);
- ComputeMaskedBits(Y, RHSZeroBits, RHSOneBits, 0, Depth);
+ 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
// 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 isKnownToBeAPowerOfTwo(cast<Operator>(V)->getOperand(0), OrZero, Depth);
+ return isKnownToBeAPowerOfTwo(cast<Operator>(V)->getOperand(0), OrZero,
+ Depth, Q);
}
return false;
///
/// Currently this routine does not support vector GEPs.
static bool isGEPKnownNonNull(GEPOperator *GEP, const DataLayout *DL,
- unsigned Depth) {
+ unsigned Depth, const Query &Q) {
if (!GEP->isInBounds() || GEP->getPointerAddressSpace() != 0)
return false;
// 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))
+ if (isKnownNonZero(GEP->getPointerOperand(), DL, Depth, Q))
return true;
// Past this, if we don't have DataLayout, we can't do much.
if (Depth++ >= MaxDepth)
continue;
- if (isKnownNonZero(GTI.getOperand(), DL, Depth))
+ 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 DataLayout *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<ConstantInt>(Ranges->getOperand(2 * i + 0));
+ ConstantInt *Upper =
+ mdconst::extract<ConstantInt>(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<Constant>(V)) {
if (C->isNullValue())
return false;
return false;
}
+ if (Instruction* I = dyn_cast<Instruction>(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<IntegerType>(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;
if (isKnownNonNull(V))
return true;
if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
- if (isGEPKnownNonNull(GEP, TD, Depth))
+ 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<SExtInst>(V) || isa<ZExtInst>(V))
- return isKnownNonZero(cast<Instruction>(V)->getOperand(0), TD, Depth);
+ return isKnownNonZero(cast<Instruction>(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.
// shl nuw can't remove any non-zero bits.
OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(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;
}
// shr exact can only shift out zero bits.
PossiblyExactOperator *BO = cast<PossiblyExactOperator>(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
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 && isKnownToBeAPowerOfTwo(Y, /*OrZero*/false, Depth))
+ if (XKnownNonNegative &&
+ isKnownToBeAPowerOfTwo(Y, /*OrZero*/false, Depth, Q))
return true;
- if (YKnownNonNegative && isKnownToBeAPowerOfTwo(X, /*OrZero*/false, Depth))
+ if (YKnownNonNegative &&
+ isKnownToBeAPowerOfTwo(X, /*OrZero*/false, Depth, Q))
return true;
}
// X * Y.
// 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<SelectInst>(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 DataLayout *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 DataLayout *TD,
- unsigned Depth) {
+unsigned ComputeNumSignBits(Value *V, const DataLayout *TD,
+ unsigned Depth, const Query &Q) {
assert((TD || V->getType()->isIntOrIntVectorTy()) &&
"ComputeNumSignBits requires a DataLayout object to operate "
"on non-integer values!");
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)
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))) {
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.
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<ConstantInt>(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.
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<ConstantInt>(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())
// 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;
// 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;
}
// 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;
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) {
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<Constant>(Op1))
if (Constant *MulC = dyn_cast<Constant>(Mul0)) {
}
}
- Value *Mul1 = NULL;
+ Value *Mul1 = nullptr;
if (ComputeMultiple(Op1, Base, Mul1, LookThroughSExt, Depth+1)) {
if (Constant *Op0C = dyn_cast<Constant>(Op0))
if (Constant *MulC = dyn_cast<Constant>(Mul1)) {
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!
return 1; // Limit search depth.
const Operator *I = dyn_cast<Operator>(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<FPMathOperator>(I))
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.
// If the top/bottom halves aren't the same, reject it.
if (Val != Val2)
- return 0;
+ return nullptr;
}
return ConstantInt::get(V->getContext(), Val);
}
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;
}
// %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;
}
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),
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.
///
if (Constant *C = dyn_cast<Constant>(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 (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,
}
// 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 DataLayout *DL) {
// Without DataLayout, conservatively assume 64-bit offsets, which is
}
Ptr = GEP->getPointerOperand();
- } else if (Operator::getOpcode(Ptr) == Instruction::BitCast) {
+ } else if (Operator::getOpcode(Ptr) == Instruction::BitCast ||
+ Operator::getOpcode(Ptr) == Instruction::AddrSpaceCast) {
Ptr = cast<Operator>(Ptr)->getOperand(0);
} else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(Ptr)) {
if (GA->mayBeOverridden())
}
-/// 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);
// Make sure the index-ee is a pointer to array of i8.
PointerType *PT = cast<PointerType>(GEP->getOperand(0)->getType());
ArrayType *AT = dyn_cast<ArrayType>(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<ConstantInt>(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
// Must be a Constant Array
const ConstantDataArray *Array =
dyn_cast<ConstantDataArray>(GV->getInitializer());
- if (Array == 0 || !Array->isString())
+ if (!Array || !Array->isString())
return false;
// Get the number of elements in the array
// 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<PHINode*, 32> &PHIs) {
+static uint64_t GetStringLengthH(Value *V, SmallPtrSetImpl<PHINode*> &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<PHINode>(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.
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;
for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) {
if (GEPOperator *GEP = dyn_cast<GEPOperator>(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<Operator>(V)->getOperand(0);
} else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
if (GA->mayBeOverridden())
} else {
// See if InstructionSimplify knows any relevant tricks.
if (Instruction *I = dyn_cast<Instruction>(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;
}
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<SelectInst>(P)) {
} 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<IntrinsicInst>(*UI);
+ for (const User *U : V->users()) {
+ const IntrinsicInst *II = dyn_cast<IntrinsicInst>(U);
if (!II) return false;
if (II->getIntrinsicID() != Intrinsic::lifetime_start &&
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<LoadInst>(Inst);
// 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<IntrinsicInst>(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:
- 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<IntrinsicInst>(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.
}
}
}
-/// isKnownNonNull - Return true if we know that the specified value is never
-/// null.
+/// 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<AllocaInst>(V)) return true;
- // A byval or inalloca argument is never null.
+ // A byval, inalloca, or nonnull argument is never null.
if (const Argument *A = dyn_cast<Argument>(V))
- return A->hasByValOrInAllocaAttr();
+ return A->hasByValOrInAllocaAttr() || A->hasNonNullAttr();
// Global values are not null unless extern weak.
if (const GlobalValue *GV = dyn_cast<GlobalValue>(V))
return !GV->hasExternalWeakLinkage();
+ // A Load tagged w/nonnull metadata is never null.
+ if (const LoadInst *LI = dyn_cast<LoadInst>(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;
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