#define LLVM_ANALYSIS_VALUETRACKING_H
#include "llvm/ADT/ArrayRef.h"
+#include "llvm/IR/Instruction.h"
#include "llvm/Support/DataTypes.h"
namespace llvm {
class DataLayout;
class StringRef;
class MDNode;
+ class AssumptionCache;
+ class DominatorTree;
+ class TargetLibraryInfo;
+ class LoopInfo;
+ class Loop;
- /// ComputeMaskedBits - Determine which of the bits specified in Mask are
- /// known to be either zero or one and return them in the KnownZero/KnownOne
- /// bit sets. This code only analyzes bits in Mask, in order to short-circuit
- /// processing.
+ /// Determine which bits of V are known to be either zero or one and return
+ /// them in the KnownZero/KnownOne bit sets.
///
/// 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
+ /// type, and vectors of integers. In the case
+ /// where V is a vector, the 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 ComputeMaskedBits(Value *V, APInt &KnownZero, APInt &KnownOne,
- const DataLayout *TD = 0, unsigned Depth = 0);
- void computeMaskedBitsLoad(const MDNode &Ranges, APInt &KnownZero);
+ void computeKnownBits(Value *V, APInt &KnownZero, APInt &KnownOne,
+ const DataLayout &DL, unsigned Depth = 0,
+ AssumptionCache *AC = nullptr,
+ const Instruction *CxtI = nullptr,
+ const DominatorTree *DT = nullptr);
+ /// Compute known bits from the range metadata.
+ /// \p KnownZero the set of bits that are known to be zero
+ void computeKnownBitsFromRangeMetadata(const MDNode &Ranges,
+ APInt &KnownZero);
+ /// Return true if LHS and RHS have no common bits set.
+ bool haveNoCommonBitsSet(Value *LHS, Value *RHS, const DataLayout &DL,
+ AssumptionCache *AC = nullptr,
+ const Instruction *CxtI = nullptr,
+ const DominatorTree *DT = nullptr);
/// ComputeSignBit - Determine whether the sign bit is known to be zero or
- /// one. Convenience wrapper around ComputeMaskedBits.
+ /// one. Convenience wrapper around computeKnownBits.
void ComputeSignBit(Value *V, bool &KnownZero, bool &KnownOne,
- const DataLayout *TD = 0, unsigned Depth = 0);
+ const DataLayout &DL, unsigned Depth = 0,
+ AssumptionCache *AC = nullptr,
+ const Instruction *CxtI = nullptr,
+ const DominatorTree *DT = nullptr);
/// isKnownToBeAPowerOfTwo - 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 type and vectors of integers. If 'OrZero' is set then
- /// returns true if the given value is either a power of two or zero.
- bool isKnownToBeAPowerOfTwo(Value *V, bool OrZero = false, unsigned Depth = 0);
+ /// return true if the given value is either a power of two or zero.
+ bool isKnownToBeAPowerOfTwo(Value *V, const DataLayout &DL,
+ bool OrZero = false, unsigned Depth = 0,
+ AssumptionCache *AC = nullptr,
+ const Instruction *CxtI = nullptr,
+ const DominatorTree *DT = nullptr);
/// 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 isKnownNonZero(Value *V, const DataLayout *TD = 0, unsigned Depth = 0);
+ bool isKnownNonZero(Value *V, const DataLayout &DL, unsigned Depth = 0,
+ AssumptionCache *AC = nullptr,
+ const Instruction *CxtI = nullptr,
+ const DominatorTree *DT = nullptr);
/// 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.
///
/// 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
+ /// type, 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 MaskedValueIsZero(Value *V, const APInt &Mask,
- const DataLayout *TD = 0, unsigned Depth = 0);
+ bool MaskedValueIsZero(Value *V, const APInt &Mask, const DataLayout &DL,
+ unsigned Depth = 0, AssumptionCache *AC = nullptr,
+ const Instruction *CxtI = nullptr,
+ const DominatorTree *DT = nullptr);
-
/// 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
///
/// 'Op' must have a scalar integer type.
///
- unsigned ComputeNumSignBits(Value *Op, const DataLayout *TD = 0,
- unsigned Depth = 0);
+ unsigned ComputeNumSignBits(Value *Op, const DataLayout &DL,
+ unsigned Depth = 0, AssumptionCache *AC = nullptr,
+ const Instruction *CxtI = nullptr,
+ const DominatorTree *DT = nullptr);
/// ComputeMultiple - This function computes the integer multiple of Base that
/// equals V. If successful, it returns true and returns the multiple in
///
bool CannotBeNegativeZero(const Value *V, unsigned Depth = 0);
+ /// CannotBeOrderedLessThanZero - Return true if we can prove that the
+ /// specified FP value is either a NaN or never less than 0.0.
+ ///
+ bool CannotBeOrderedLessThanZero(const Value *V, unsigned Depth = 0);
+
/// 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
/// true for all i8 values obviously, but is also true for i32 0, i32 -1,
/// insertvalues when a part of a nested struct is extracted.
Value *FindInsertedValue(Value *V,
ArrayRef<unsigned> idx_range,
- Instruction *InsertBefore = 0);
+ Instruction *InsertBefore = 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.
Value *GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
- const DataLayout &TD);
+ const DataLayout &DL);
static inline const Value *
GetPointerBaseWithConstantOffset(const Value *Ptr, int64_t &Offset,
- const DataLayout &TD) {
- return GetPointerBaseWithConstantOffset(const_cast<Value*>(Ptr), Offset,TD);
+ const DataLayout &DL) {
+ return GetPointerBaseWithConstantOffset(const_cast<Value *>(Ptr), Offset,
+ DL);
}
/// getConstantStringInfo - This function computes the length of a
/// being addressed. Note that the returned value has pointer type if the
/// specified value does. If the MaxLookup value is non-zero, it limits the
/// number of instructions to be stripped off.
- Value *GetUnderlyingObject(Value *V, const DataLayout *TD = 0,
+ Value *GetUnderlyingObject(Value *V, const DataLayout &DL,
unsigned MaxLookup = 6);
- static inline const Value *
- GetUnderlyingObject(const Value *V, const DataLayout *TD = 0,
- unsigned MaxLookup = 6) {
- return GetUnderlyingObject(const_cast<Value *>(V), TD, MaxLookup);
+ static inline const Value *GetUnderlyingObject(const Value *V,
+ const DataLayout &DL,
+ unsigned MaxLookup = 6) {
+ return GetUnderlyingObject(const_cast<Value *>(V), DL, MaxLookup);
}
- /// GetUnderlyingObjects - This method is similar to GetUnderlyingObject
- /// except that it can look through phi and select instructions and return
- /// multiple objects.
- void GetUnderlyingObjects(Value *V,
- SmallVectorImpl<Value *> &Objects,
- const DataLayout *TD = 0,
+ /// \brief This method is similar to GetUnderlyingObject except that it can
+ /// look through phi and select instructions and return multiple objects.
+ ///
+ /// If LoopInfo is passed, loop phis are further analyzed. If a pointer
+ /// accesses different objects in each iteration, we don't look through the
+ /// phi node. E.g. consider this loop nest:
+ ///
+ /// int **A;
+ /// for (i)
+ /// for (j) {
+ /// A[i][j] = A[i-1][j] * B[j]
+ /// }
+ ///
+ /// This is transformed by Load-PRE to stash away A[i] for the next iteration
+ /// of the outer loop:
+ ///
+ /// Curr = A[0]; // Prev_0
+ /// for (i: 1..N) {
+ /// Prev = Curr; // Prev = PHI (Prev_0, Curr)
+ /// Curr = A[i];
+ /// for (j: 0..N) {
+ /// Curr[j] = Prev[j] * B[j]
+ /// }
+ /// }
+ ///
+ /// Since A[i] and A[i-1] are independent pointers, getUnderlyingObjects
+ /// should not assume that Curr and Prev share the same underlying object thus
+ /// it shouldn't look through the phi above.
+ void GetUnderlyingObjects(Value *V, SmallVectorImpl<Value *> &Objects,
+ const DataLayout &DL, LoopInfo *LI = nullptr,
unsigned MaxLookup = 6);
/// onlyUsedByLifetimeMarkers - Return true if the only users of this pointer
/// are lifetime markers.
bool onlyUsedByLifetimeMarkers(const Value *V);
+ /// isDereferenceablePointer - Return true if this is always a dereferenceable
+ /// pointer. If the context instruction is specified perform context-sensitive
+ /// analysis and return true if the pointer is dereferenceable at the
+ /// specified instruction.
+ bool isDereferenceablePointer(const Value *V, const DataLayout &DL,
+ const Instruction *CtxI = nullptr,
+ const DominatorTree *DT = nullptr,
+ const TargetLibraryInfo *TLI = nullptr);
+
/// isSafeToSpeculativelyExecute - Return true if the instruction does not
/// have any effects besides calculating the result and does not have
/// undefined behavior.
/// memory leak. It also returns false for instructions related to control
/// flow, specifically terminators and PHI nodes.
///
- /// This method only looks at the instruction itself and its operands, so if
- /// this method returns true, it is safe to move the instruction as long as
- /// the correct dominance relationships for the operands and users hold.
- /// However, this method can return true for instructions that read memory;
+ /// If the CtxI is specified this method performs context-sensitive analysis
+ /// and returns true if it is safe to execute the instruction immediately
+ /// before the CtxI.
+ ///
+ /// If the CtxI is NOT specified this method only looks at the instruction
+ /// itself and its operands, so if this method returns true, it is safe to
+ /// move the instruction as long as the correct dominance relationships for
+ /// the operands and users hold.
+ ///
+ /// This method can return true for instructions that read memory;
/// for such instructions, moving them may change the resulting value.
bool isSafeToSpeculativelyExecute(const Value *V,
- const DataLayout *TD = 0);
+ const Instruction *CtxI = nullptr,
+ const DominatorTree *DT = nullptr,
+ const TargetLibraryInfo *TLI = nullptr);
+
+ /// Returns true if the result or effects of the given instructions \p I
+ /// depend on or influence global memory.
+ /// Memory dependence arises for example if the the instruction reads from
+ /// memory or may produce effects or undefined behaviour. Memory dependent
+ /// instructions generally cannot be reorderd with respect to other memory
+ /// dependent instructions or moved into non-dominated basic blocks.
+ /// Instructions which just compute a value based on the values of their
+ /// operands are not memory dependent.
+ bool mayBeMemoryDependent(const Instruction &I);
+
+ /// isKnownNonNull - Return true if this pointer couldn't possibly be null by
+ /// its definition. This returns true for allocas, non-extern-weak globals
+ /// and byval arguments.
+ bool isKnownNonNull(const Value *V, const TargetLibraryInfo *TLI = nullptr);
+
+ /// isKnownNonNullAt - Return true if this pointer couldn't possibly be null.
+ /// If the context instruction is specified perform context-sensitive analysis
+ /// and return true if the pointer couldn't possibly be null at the specified
+ /// instruction.
+ bool isKnownNonNullAt(const Value *V,
+ const Instruction *CtxI = nullptr,
+ const DominatorTree *DT = nullptr,
+ const TargetLibraryInfo *TLI = nullptr);
+
+ /// Return true if it is valid to use the assumptions provided by an
+ /// assume intrinsic, I, at the point in the control-flow identified by the
+ /// context instruction, CxtI.
+ bool isValidAssumeForContext(const Instruction *I, const Instruction *CxtI,
+ const DominatorTree *DT = nullptr);
+
+ enum class OverflowResult { AlwaysOverflows, MayOverflow, NeverOverflows };
+ OverflowResult computeOverflowForUnsignedMul(Value *LHS, Value *RHS,
+ const DataLayout &DL,
+ AssumptionCache *AC,
+ const Instruction *CxtI,
+ const DominatorTree *DT);
+ OverflowResult computeOverflowForUnsignedAdd(Value *LHS, Value *RHS,
+ const DataLayout &DL,
+ AssumptionCache *AC,
+ const Instruction *CxtI,
+ const DominatorTree *DT);
+
+ /// Return true if this function can prove that the instruction I will
+ /// always transfer execution to one of its successors (including the next
+ /// instruction that follows within a basic block). E.g. this is not
+ /// guaranteed for function calls that could loop infinitely.
+ ///
+ /// In other words, this function returns false for instructions that may
+ /// transfer execution or fail to transfer execution in a way that is not
+ /// captured in the CFG nor in the sequence of instructions within a basic
+ /// block.
+ ///
+ /// Undefined behavior is assumed not to happen, so e.g. division is
+ /// guaranteed to transfer execution to the following instruction even
+ /// though division by zero might cause undefined behavior.
+ bool isGuaranteedToTransferExecutionToSuccessor(const Instruction *I);
+
+ /// Return true if this function can prove that the instruction I
+ /// is executed for every iteration of the loop L.
+ ///
+ /// Note that this currently only considers the loop header.
+ bool isGuaranteedToExecuteForEveryIteration(const Instruction *I,
+ const Loop *L);
+
+ /// Return true if this function can prove that I is guaranteed to yield
+ /// full-poison (all bits poison) if at least one of its operands are
+ /// full-poison (all bits poison).
+ ///
+ /// The exact rules for how poison propagates through instructions have
+ /// not been settled as of 2015-07-10, so this function is conservative
+ /// and only considers poison to be propagated in uncontroversial
+ /// cases. There is no attempt to track values that may be only partially
+ /// poison.
+ bool propagatesFullPoison(const Instruction *I);
+
+ /// Return either nullptr or an operand of I such that I will trigger
+ /// undefined behavior if I is executed and that operand has a full-poison
+ /// value (all bits poison).
+ const Value *getGuaranteedNonFullPoisonOp(const Instruction *I);
+
+ /// Return true if this function can prove that if PoisonI is executed
+ /// and yields a full-poison value (all bits poison), then that will
+ /// trigger undefined behavior.
+ ///
+ /// Note that this currently only considers the basic block that is
+ /// the parent of I.
+ bool isKnownNotFullPoison(const Instruction *PoisonI);
+
+ /// \brief Specific patterns of select instructions we can match.
+ enum SelectPatternFlavor {
+ SPF_UNKNOWN = 0,
+ SPF_SMIN, /// Signed minimum
+ SPF_UMIN, /// Unsigned minimum
+ SPF_SMAX, /// Signed maximum
+ SPF_UMAX, /// Unsigned maximum
+ SPF_FMINNUM, /// Floating point minnum
+ SPF_FMAXNUM, /// Floating point maxnum
+ SPF_ABS, /// Absolute value
+ SPF_NABS /// Negated absolute value
+ };
+ /// \brief Behavior when a floating point min/max is given one NaN and one
+ /// non-NaN as input.
+ enum SelectPatternNaNBehavior {
+ SPNB_NA = 0, /// NaN behavior not applicable.
+ SPNB_RETURNS_NAN, /// Given one NaN input, returns the NaN.
+ SPNB_RETURNS_OTHER, /// Given one NaN input, returns the non-NaN.
+ SPNB_RETURNS_ANY /// Given one NaN input, can return either (or
+ /// it has been determined that no operands can
+ /// be NaN).
+ };
+ struct SelectPatternResult {
+ SelectPatternFlavor Flavor;
+ SelectPatternNaNBehavior NaNBehavior; /// Only applicable if Flavor is
+ /// SPF_FMINNUM or SPF_FMAXNUM.
+ bool Ordered; /// When implementing this min/max pattern as
+ /// fcmp; select, does the fcmp have to be
+ /// ordered?
+ };
+ /// Pattern match integer [SU]MIN, [SU]MAX and ABS idioms, returning the kind
+ /// and providing the out parameter results if we successfully match.
+ ///
+ /// If CastOp is not nullptr, also match MIN/MAX idioms where the type does
+ /// not match that of the original select. If this is the case, the cast
+ /// operation (one of Trunc,SExt,Zext) that must be done to transform the
+ /// type of LHS and RHS into the type of V is returned in CastOp.
+ ///
+ /// For example:
+ /// %1 = icmp slt i32 %a, i32 4
+ /// %2 = sext i32 %a to i64
+ /// %3 = select i1 %1, i64 %2, i64 4
+ ///
+ /// -> LHS = %a, RHS = i32 4, *CastOp = Instruction::SExt
+ ///
+ SelectPatternResult matchSelectPattern(Value *V, Value *&LHS, Value *&RHS,
+ Instruction::CastOps *CastOp = nullptr);
} // end namespace llvm
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