//===- ConstantRange.h - Represent a range ----------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Represent a range of possible values that may occur when the program is run
// for an integral value. This keeps track of a lower and upper bound for the
// constant, which MAY wrap around the end of the numeric range. To do this, it
// keeps track of a [lower, upper) bound, which specifies an interval just like
// STL iterators. When used with boolean values, the following are important
// ranges: :
//
// [F, F) = {} = Empty set
// [T, F) = {T}
// [F, T) = {F}
// [T, T) = {F, T} = Full set
//
// The other integral ranges use min/max values for special range values. For
// example, for 8-bit types, it uses:
// [0, 0) = {} = Empty set
// [255, 255) = {0..255} = Full Set
//
// Note that ConstantRange can be used to represent either signed or
// unsigned ranges.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_IR_CONSTANTRANGE_H
#define LLVM_IR_CONSTANTRANGE_H
#include "llvm/ADT/APInt.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/Support/DataTypes.h"
namespace llvm {
class MDNode;
/// This class represents a range of values.
class LLVM_NODISCARD ConstantRange {
APInt Lower, Upper;
public:
/// Initialize a full (the default) or empty set for the specified bit width.
explicit ConstantRange(uint32_t BitWidth, bool isFullSet = true);
/// Initialize a range to hold the single specified value.
ConstantRange(APInt Value);
/// @brief Initialize a range of values explicitly. This will assert out if
/// Lower==Upper and Lower != Min or Max value for its type. It will also
/// assert out if the two APInt's are not the same bit width.
ConstantRange(APInt Lower, APInt Upper);
/// Produce the smallest range such that all values that may satisfy the given
/// predicate with any value contained within Other is contained in the
/// returned range. Formally, this returns a superset of
/// 'union over all y in Other . { x : icmp op x y is true }'. If the exact
/// answer is not representable as a ConstantRange, the return value will be a
/// proper superset of the above.
///
/// Example: Pred = ult and Other = i8 [2, 5) returns Result = [0, 4)
static ConstantRange makeAllowedICmpRegion(CmpInst::Predicate Pred,
const ConstantRange &Other);
/// Produce the largest range such that all values in the returned range
/// satisfy the given predicate with all values contained within Other.
/// Formally, this returns a subset of
/// 'intersection over all y in Other . { x : icmp op x y is true }'. If the
/// exact answer is not representable as a ConstantRange, the return value
/// will be a proper subset of the above.
///
/// Example: Pred = ult and Other = i8 [2, 5) returns [0, 2)
static ConstantRange makeSatisfyingICmpRegion(CmpInst::Predicate Pred,
const ConstantRange &Other);
/// Produce the exact range such that all values in the returned range satisfy
/// the given predicate with any value contained within Other. Formally, this
/// returns the exact answer when the superset of 'union over all y in Other
/// is exactly same as the subset of intersection over all y in Other.
/// { x : icmp op x y is true}'.
///
/// Example: Pred = ult and Other = i8 3 returns [0, 3)
static ConstantRange makeExactICmpRegion(CmpInst::Predicate Pred,
const APInt &Other);
/// Return the largest range containing all X such that "X BinOpC Y" is
/// guaranteed not to wrap (overflow) for all Y in Other.
///
/// NB! The returned set does *not* contain **all** possible values of X for
/// which "X BinOpC Y" does not wrap -- some viable values of X may be
/// missing, so you cannot use this to constrain X's range. E.g. in the last
/// example, "(-2) + 1" is both nsw and nuw (so the "X" could be -2), but (-2)
/// is not in the set returned.
///
/// Examples:
/// typedef OverflowingBinaryOperator OBO;
/// #define MGNR makeGuaranteedNoWrapRegion
/// MGNR(Add, [i8 1, 2), OBO::NoSignedWrap) == [-128, 127)
/// MGNR(Add, [i8 1, 2), OBO::NoUnsignedWrap) == [0, -1)
/// MGNR(Add, [i8 0, 1), OBO::NoUnsignedWrap) == Full Set
/// MGNR(Add, [i8 1, 2), OBO::NoUnsignedWrap | OBO::NoSignedWrap)
/// == [0,INT_MAX)
/// MGNR(Add, [i8 -1, 6), OBO::NoSignedWrap) == [INT_MIN+1, INT_MAX-4)
static ConstantRange makeGuaranteedNoWrapRegion(Instruction::BinaryOps BinOp,
const ConstantRange &Other,
unsigned NoWrapKind);
/// Set up \p Pred and \p RHS such that
/// ConstantRange::makeExactICmpRegion(Pred, RHS) == *this. Return true if
/// successful.
bool getEquivalentICmp(CmpInst::Predicate &Pred, APInt &RHS) const;
/// Return the lower value for this range.
const APInt &getLower() const { return Lower; }
/// Return the upper value for this range.
const APInt &getUpper() const { return Upper; }
/// Get the bit width of this ConstantRange.
uint32_t getBitWidth() const { return Lower.getBitWidth(); }
/// Return true if this set contains all of the elements possible
/// for this data-type.
bool isFullSet() const;
/// Return true if this set contains no members.
bool isEmptySet() const;
/// Return true if this set wraps around the top of the range.
/// For example: [100, 8).
bool isWrappedSet() const;
/// Return true if this set wraps around the INT_MIN of
/// its bitwidth. For example: i8 [120, 140).
bool isSignWrappedSet() const;
/// Return true if the specified value is in the set.
bool contains(const APInt &Val) const;
/// Return true if the other range is a subset of this one.
bool contains(const ConstantRange &CR) const;
/// If this set contains a single element, return it, otherwise return null.
const APInt *getSingleElement() const {
if (Upper == Lower + 1)
return &Lower;
return nullptr;
}
/// If this set contains all but a single element, return it, otherwise return
/// null.
const APInt *getSingleMissingElement() const {
if (Lower == Upper + 1)
return &Upper;
return nullptr;
}
/// Return true if this set contains exactly one member.
bool isSingleElement() const { return getSingleElement() != nullptr; }
/// Return the number of elements in this set.
APInt getSetSize() const;
/// Compare set size of this range with the range CR.
bool isSizeStrictlySmallerThan(const ConstantRange &CR) const;
// Compare set size of this range with Value.
bool isSizeLargerThan(uint64_t MaxSize) const;
/// Return the largest unsigned value contained in the ConstantRange.
APInt getUnsignedMax() const;
/// Return the smallest unsigned value contained in the ConstantRange.
APInt getUnsignedMin() const;
/// Return the largest signed value contained in the ConstantRange.
APInt getSignedMax() const;
/// Return the smallest signed value contained in the ConstantRange.
APInt getSignedMin() const;
/// Return true if this range is equal to another range.
bool operator==(const ConstantRange &CR) const {
return Lower == CR.Lower && Upper == CR.Upper;
}
bool operator!=(const ConstantRange &CR) const {
return !operator==(CR);
}
/// Subtract the specified constant from the endpoints of this constant range.
ConstantRange subtract(const APInt &CI) const;
/// Subtract the specified range from this range (aka relative complement of
/// the sets).
ConstantRange difference(const ConstantRange &CR) const;
/// Return the range that results from the intersection of
/// this range with another range. The resultant range is guaranteed to
/// include all elements contained in both input ranges, and to have the
/// smallest possible set size that does so. Because there may be two
/// intersections with the same set size, A.intersectWith(B) might not
/// be equal to B.intersectWith(A).
ConstantRange intersectWith(const ConstantRange &CR) const;
/// Return the range that results from the union of this range
/// with another range. The resultant range is guaranteed to include the
/// elements of both sets, but may contain more. For example, [3, 9) union
/// [12,15) is [3, 15), which includes 9, 10, and 11, which were not included
/// in either set before.
ConstantRange unionWith(const ConstantRange &CR) const;
/// Return a new range representing the possible values resulting
/// from an application of the specified cast operator to this range. \p
/// BitWidth is the target bitwidth of the cast. For casts which don't
/// change bitwidth, it must be the same as the source bitwidth. For casts
/// which do change bitwidth, the bitwidth must be consistent with the
/// requested cast and source bitwidth.
ConstantRange castOp(Instruction::CastOps CastOp,
uint32_t BitWidth) const;
/// Return a new range in the specified integer type, which must
/// be strictly larger than the current type. The returned range will
/// correspond to the possible range of values if the source range had been
/// zero extended to BitWidth.
ConstantRange zeroExtend(uint32_t BitWidth) const;
/// Return a new range in the specified integer type, which must
/// be strictly larger than the current type. The returned range will
/// correspond to the possible range of values if the source range had been
/// sign extended to BitWidth.
ConstantRange signExtend(uint32_t BitWidth) const;
/// Return a new range in the specified integer type, which must be
/// strictly smaller than the current type. The returned range will
/// correspond to the possible range of values if the source range had been
/// truncated to the specified type.
ConstantRange truncate(uint32_t BitWidth) const;
/// Make this range have the bit width given by \p BitWidth. The
/// value is zero extended, truncated, or left alone to make it that width.
ConstantRange zextOrTrunc(uint32_t BitWidth) const;
/// Make this range have the bit width given by \p BitWidth. The
/// value is sign extended, truncated, or left alone to make it that width.
ConstantRange sextOrTrunc(uint32_t BitWidth) const;
/// Return a new range representing the possible values resulting
/// from an application of the specified binary operator to an left hand side
/// of this range and a right hand side of \p Other.
ConstantRange binaryOp(Instruction::BinaryOps BinOp,
const ConstantRange &Other) const;
/// Return a new range representing the possible values resulting
/// from an addition of a value in this range and a value in \p Other.
ConstantRange add(const ConstantRange &Other) const;
/// Return a new range representing the possible values resulting from a
/// known NSW addition of a value in this range and \p Other constant.
ConstantRange addWithNoSignedWrap(const APInt &Other) const;
/// Return a new range representing the possible values resulting
/// from a subtraction of a value in this range and a value in \p Other.
ConstantRange sub(const ConstantRange &Other) const;
/// Return a new range representing the possible values resulting
/// from a multiplication of a value in this range and a value in \p Other,
/// treating both this and \p Other as unsigned ranges.
ConstantRange multiply(const ConstantRange &Other) const;
/// Return a new range representing the possible values resulting
/// from a signed maximum of a value in this range and a value in \p Other.
ConstantRange smax(const ConstantRange &Other) const;
/// Return a new range representing the possible values resulting
/// from an unsigned maximum of a value in this range and a value in \p Other.
ConstantRange umax(const ConstantRange &Other) const;
/// Return a new range representing the possible values resulting
/// from a signed minimum of a value in this range and a value in \p Other.
ConstantRange smin(const ConstantRange &Other) const;
/// Return a new range representing the possible values resulting
/// from an unsigned minimum of a value in this range and a value in \p Other.
ConstantRange umin(const ConstantRange &Other) const;
/// Return a new range representing the possible values resulting
/// from an unsigned division of a value in this range and a value in
/// \p Other.
ConstantRange udiv(const ConstantRange &Other) const;
/// Return a new range representing the possible values resulting
/// from a binary-and of a value in this range by a value in \p Other.
ConstantRange binaryAnd(const ConstantRange &Other) const;
/// Return a new range representing the possible values resulting
/// from a binary-or of a value in this range by a value in \p Other.
ConstantRange binaryOr(const ConstantRange &Other) const;
/// Return a new range representing the possible values resulting
/// from a left shift of a value in this range by a value in \p Other.
/// TODO: This isn't fully implemented yet.
ConstantRange shl(const ConstantRange &Other) const;
/// Return a new range representing the possible values resulting from a
/// logical right shift of a value in this range and a value in \p Other.
ConstantRange lshr(const ConstantRange &Other) const;
/// Return a new range that is the logical not of the current set.
ConstantRange inverse() const;
/// Print out the bounds to a stream.
void print(raw_ostream &OS) const;
/// Allow printing from a debugger easily.
void dump() const;
};
inline raw_ostream &operator<<(raw_ostream &OS, const ConstantRange &CR) {
CR.print(OS);
return OS;
}
/// Parse out a conservative ConstantRange from !range metadata.
///
/// E.g. if RangeMD is !{i32 0, i32 10, i32 15, i32 20} then return [0, 20).
ConstantRange getConstantRangeFromMetadata(const MDNode &RangeMD);
} // End llvm namespace
#endif