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da5f3a3ca5
Summary: This change splits `makeICmpRegion` into `makeAllowedICmpRegion` and `makeSatisfyingICmpRegion` with slightly different contracts. The first one is useful for determining what values some expression //may// take, given that a certain `icmp` evaluates to true. The second one is useful for determining what values are guaranteed to //satisfy// a given `icmp`. Reviewers: nlewycky Reviewed By: nlewycky Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D8345 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232575 91177308-0d34-0410-b5e6-96231b3b80d8
279 lines
10 KiB
C++
279 lines
10 KiB
C++
//===- ConstantRange.h - Represent a range ----------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Represent a range of possible values that may occur when the program is run
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// for an integral value. This keeps track of a lower and upper bound for the
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// constant, which MAY wrap around the end of the numeric range. To do this, it
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// keeps track of a [lower, upper) bound, which specifies an interval just like
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// STL iterators. When used with boolean values, the following are important
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// ranges: :
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//
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// [F, F) = {} = Empty set
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// [T, F) = {T}
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// [F, T) = {F}
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// [T, T) = {F, T} = Full set
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//
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// The other integral ranges use min/max values for special range values. For
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// example, for 8-bit types, it uses:
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// [0, 0) = {} = Empty set
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// [255, 255) = {0..255} = Full Set
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//
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// Note that ConstantRange can be used to represent either signed or
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// unsigned ranges.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_IR_CONSTANTRANGE_H
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#define LLVM_IR_CONSTANTRANGE_H
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#include "llvm/ADT/APInt.h"
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#include "llvm/IR/InstrTypes.h"
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#include "llvm/Support/DataTypes.h"
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namespace llvm {
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/// This class represents a range of values.
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///
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class ConstantRange {
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APInt Lower, Upper;
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// If we have move semantics, pass APInts by value and move them into place.
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typedef APInt APIntMoveTy;
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public:
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/// Initialize a full (the default) or empty set for the specified bit width.
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///
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explicit ConstantRange(uint32_t BitWidth, bool isFullSet = true);
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/// Initialize a range to hold the single specified value.
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///
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ConstantRange(APIntMoveTy Value);
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/// @brief Initialize a range of values explicitly. This will assert out if
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/// Lower==Upper and Lower != Min or Max value for its type. It will also
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/// assert out if the two APInt's are not the same bit width.
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ConstantRange(APIntMoveTy Lower, APIntMoveTy Upper);
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/// Produce the smallest range such that all values that may satisfy the given
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/// predicate with any value contained within Other is contained in the
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/// returned range. Formally, this returns a superset of
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/// 'union over all y in Other . { x : icmp op x y is true }'. If the exact
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/// answer is not representable as a ConstantRange, the return value will be a
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/// proper superset of the above.
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///
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/// Example: Pred = ult and Other = i8 [2, 5) returns Result = [0, 4)
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static ConstantRange makeAllowedICmpRegion(CmpInst::Predicate Pred,
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const ConstantRange &Other);
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/// Produce the largest range such that all values in the returned range
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/// satisfy the given predicate with all values contained within Other.
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/// Formally, this returns a subset of
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/// 'intersection over all y in Other . { x : icmp op x y is true }'. If the
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/// exact answer is not representable as a ConstantRange, the return value
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/// will be a proper subset of the above.
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///
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/// Example: Pred = ult and Other = i8 [2, 5) returns [0, 2)
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static ConstantRange makeSatisfyingICmpRegion(CmpInst::Predicate Pred,
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const ConstantRange &Other);
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/// Return the lower value for this range.
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///
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const APInt &getLower() const { return Lower; }
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/// Return the upper value for this range.
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///
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const APInt &getUpper() const { return Upper; }
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/// Get the bit width of this ConstantRange.
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///
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uint32_t getBitWidth() const { return Lower.getBitWidth(); }
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/// Return true if this set contains all of the elements possible
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/// for this data-type.
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///
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bool isFullSet() const;
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/// Return true if this set contains no members.
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///
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bool isEmptySet() const;
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/// Return true if this set wraps around the top of the range.
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/// For example: [100, 8).
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///
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bool isWrappedSet() const;
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/// Return true if this set wraps around the INT_MIN of
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/// its bitwidth. For example: i8 [120, 140).
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///
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bool isSignWrappedSet() const;
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/// Return true if the specified value is in the set.
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///
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bool contains(const APInt &Val) const;
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/// Return true if the other range is a subset of this one.
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///
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bool contains(const ConstantRange &CR) const;
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/// If this set contains a single element, return it, otherwise return null.
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///
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const APInt *getSingleElement() const {
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if (Upper == Lower + 1)
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return &Lower;
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return nullptr;
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}
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/// Return true if this set contains exactly one member.
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///
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bool isSingleElement() const { return getSingleElement() != nullptr; }
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/// Return the number of elements in this set.
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///
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APInt getSetSize() const;
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/// Return the largest unsigned value contained in the ConstantRange.
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///
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APInt getUnsignedMax() const;
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/// Return the smallest unsigned value contained in the ConstantRange.
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///
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APInt getUnsignedMin() const;
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/// Return the largest signed value contained in the ConstantRange.
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///
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APInt getSignedMax() const;
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/// Return the smallest signed value contained in the ConstantRange.
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///
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APInt getSignedMin() const;
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/// Return true if this range is equal to another range.
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///
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bool operator==(const ConstantRange &CR) const {
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return Lower == CR.Lower && Upper == CR.Upper;
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}
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bool operator!=(const ConstantRange &CR) const {
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return !operator==(CR);
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}
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/// Subtract the specified constant from the endpoints of this constant range.
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ConstantRange subtract(const APInt &CI) const;
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/// \brief Subtract the specified range from this range (aka relative
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/// complement of the sets).
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ConstantRange difference(const ConstantRange &CR) const;
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/// Return the range that results from the intersection of
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/// this range with another range. The resultant range is guaranteed to
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/// include all elements contained in both input ranges, and to have the
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/// smallest possible set size that does so. Because there may be two
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/// intersections with the same set size, A.intersectWith(B) might not
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/// be equal to B.intersectWith(A).
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///
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ConstantRange intersectWith(const ConstantRange &CR) const;
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/// Return the range that results from the union of this range
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/// with another range. The resultant range is guaranteed to include the
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/// elements of both sets, but may contain more. For example, [3, 9) union
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/// [12,15) is [3, 15), which includes 9, 10, and 11, which were not included
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/// in either set before.
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///
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ConstantRange unionWith(const ConstantRange &CR) const;
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/// Return a new range in the specified integer type, which must
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/// be strictly larger than the current type. The returned range will
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/// correspond to the possible range of values if the source range had been
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/// zero extended to BitWidth.
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ConstantRange zeroExtend(uint32_t BitWidth) const;
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/// Return a new range in the specified integer type, which must
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/// be strictly larger than the current type. The returned range will
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/// correspond to the possible range of values if the source range had been
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/// sign extended to BitWidth.
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ConstantRange signExtend(uint32_t BitWidth) const;
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/// Return a new range in the specified integer type, which must be
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/// strictly smaller than the current type. The returned range will
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/// correspond to the possible range of values if the source range had been
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/// truncated to the specified type.
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ConstantRange truncate(uint32_t BitWidth) const;
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/// Make this range have the bit width given by \p BitWidth. The
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/// value is zero extended, truncated, or left alone to make it that width.
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ConstantRange zextOrTrunc(uint32_t BitWidth) const;
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/// Make this range have the bit width given by \p BitWidth. The
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/// value is sign extended, truncated, or left alone to make it that width.
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ConstantRange sextOrTrunc(uint32_t BitWidth) const;
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/// Return a new range representing the possible values resulting
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/// from an addition of a value in this range and a value in \p Other.
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ConstantRange add(const ConstantRange &Other) const;
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/// Return a new range representing the possible values resulting
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/// from a subtraction of a value in this range and a value in \p Other.
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ConstantRange sub(const ConstantRange &Other) const;
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/// Return a new range representing the possible values resulting
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/// from a multiplication of a value in this range and a value in \p Other,
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/// treating both this and \p Other as unsigned ranges.
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ConstantRange multiply(const ConstantRange &Other) const;
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/// Return a new range representing the possible values resulting
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/// from a signed maximum of a value in this range and a value in \p Other.
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ConstantRange smax(const ConstantRange &Other) const;
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/// Return a new range representing the possible values resulting
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/// from an unsigned maximum of a value in this range and a value in \p Other.
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ConstantRange umax(const ConstantRange &Other) const;
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/// Return a new range representing the possible values resulting
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/// from an unsigned division of a value in this range and a value in
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/// \p Other.
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ConstantRange udiv(const ConstantRange &Other) const;
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/// Return a new range representing the possible values resulting
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/// from a binary-and of a value in this range by a value in \p Other.
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ConstantRange binaryAnd(const ConstantRange &Other) const;
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/// Return a new range representing the possible values resulting
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/// from a binary-or of a value in this range by a value in \p Other.
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ConstantRange binaryOr(const ConstantRange &Other) const;
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/// Return a new range representing the possible values resulting
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/// from a left shift of a value in this range by a value in \p Other.
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/// TODO: This isn't fully implemented yet.
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ConstantRange shl(const ConstantRange &Other) const;
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/// Return a new range representing the possible values resulting from a
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/// logical right shift of a value in this range and a value in \p Other.
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ConstantRange lshr(const ConstantRange &Other) const;
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/// Return a new range that is the logical not of the current set.
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///
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ConstantRange inverse() const;
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/// Print out the bounds to a stream.
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///
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void print(raw_ostream &OS) const;
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/// Allow printing from a debugger easily.
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///
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void dump() const;
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};
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inline raw_ostream &operator<<(raw_ostream &OS, const ConstantRange &CR) {
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CR.print(OS);
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return OS;
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}
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} // End llvm namespace
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#endif
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