include/llvm/Support/ConstantRange.h

   1 //===-- llvm/Support/ConstantRange.h - Represent a range --------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // Represent a range of possible values that may occur when the program is run
  11 // for an integral value.  This keeps track of a lower and upper bound for the
  12 // constant, which MAY wrap around the end of the numeric range.  To do this, it
  13 // keeps track of a [lower, upper) bound, which specifies an interval just like
  14 // STL iterators.  When used with boolean values, the following are important
  15 // ranges: :
  16 //
  17 //  [F, F) = {}     = Empty set
  18 //  [T, F) = {T}
  19 //  [F, T) = {F}
  20 //  [T, T) = {F, T} = Full set
  21 //
  22 // The other integral ranges use min/max values for special range values. For
  23 // example, for 8-bit types, it uses:
  24 // [0, 0)     = {}       = Empty set
  25 // [255, 255) = {0..255} = Full Set
  26 //
  27 // Note that ConstantRange can be used to represent either signed or
  28 // unsigned ranges.
  29 //
  30 //===----------------------------------------------------------------------===//
  31
  32 #ifndef LLVM_SUPPORT_CONSTANT_RANGE_H
  33 #define LLVM_SUPPORT_CONSTANT_RANGE_H
  34
  35 #include "llvm/ADT/APInt.h"
  36 #include "llvm/System/DataTypes.h"
  37
  38 namespace llvm {
  39
  40 /// ConstantRange - This class represents an range of values.
  41 ///
  42 class ConstantRange {
  43   APInt Lower, Upper;
  44
  45 public:
  46   /// Initialize a full (the default) or empty set for the specified bit width.
  47   ///
  48   explicit ConstantRange(uint32_t BitWidth, bool isFullSet = true);
  49
  50   /// Initialize a range to hold the single specified value.
  51   ///
  52   ConstantRange(const APInt &Value);
  53
  54   /// @brief Initialize a range of values explicitly. This will assert out if
  55   /// Lower==Upper and Lower != Min or Max value for its type. It will also
  56   /// assert out if the two APInt's are not the same bit width.
  57   ConstantRange(const APInt& Lower, const APInt& Upper);
  58
  59   /// makeICmpRegion - Produce the smallest range that contains all values that
  60   /// might satisfy the comparison specified by Pred when compared to any value
  61   /// contained within Other.
  62   ///
  63   /// Solves for range X in 'for all x in X, there exists a y in Y such that
  64   /// icmp op x, y is true'. Every value that might make the comparison true
  65   /// is included in the resulting range.
  66   static ConstantRange makeICmpRegion(unsigned Pred,
  67                                       const ConstantRange &Other);
  68
  69   /// getLower - Return the lower value for this range...
  70   ///
  71   const APInt &getLower() const { return Lower; }
  72
  73   /// getUpper - Return the upper value for this range...
  74   ///
  75   const APInt &getUpper() const { return Upper; }
  76
  77   /// getBitWidth - get the bit width of this ConstantRange
  78   ///
  79   uint32_t getBitWidth() const { return Lower.getBitWidth(); }
  80
  81   /// isFullSet - Return true if this set contains all of the elements possible
  82   /// for this data-type
  83   ///
  84   bool isFullSet() const;
  85
  86   /// isEmptySet - Return true if this set contains no members.
  87   ///
  88   bool isEmptySet() const;
  89
  90   /// isWrappedSet - Return true if this set wraps around the top of the range,
  91   /// for example: [100, 8)
  92   ///
  93   bool isWrappedSet() const;
  94
  95   /// contains - Return true if the specified value is in the set.
  96   ///
  97   bool contains(const APInt &Val) const;
  98
  99   /// contains - Return true if the other range is a subset of this one.
 100   ///
 101   bool contains(const ConstantRange &CR) const;
 102
 103   /// getSingleElement - If this set contains a single element, return it,
 104   /// otherwise return null.
 105   ///
 106   const APInt *getSingleElement() const {
 107     if (Upper == Lower + 1)
 108       return &Lower;
 109     return 0;
 110   }
 111
 112   /// isSingleElement - Return true if this set contains exactly one member.
 113   ///
 114   bool isSingleElement() const { return getSingleElement() != 0; }
 115
 116   /// getSetSize - Return the number of elements in this set.
 117   ///
 118   APInt getSetSize() const;
 119
 120   /// getUnsignedMax - Return the largest unsigned value contained in the
 121   /// ConstantRange.
 122   ///
 123   APInt getUnsignedMax() const;
 124
 125   /// getUnsignedMin - Return the smallest unsigned value contained in the
 126   /// ConstantRange.
 127   ///
 128   APInt getUnsignedMin() const;
 129
 130   /// getSignedMax - Return the largest signed value contained in the
 131   /// ConstantRange.
 132   ///
 133   APInt getSignedMax() const;
 134
 135   /// getSignedMin - Return the smallest signed value contained in the
 136   /// ConstantRange.
 137   ///
 138   APInt getSignedMin() const;
 139
 140   /// operator== - Return true if this range is equal to another range.
 141   ///
 142   bool operator==(const ConstantRange &CR) const {
 143     return Lower == CR.Lower && Upper == CR.Upper;
 144   }
 145   bool operator!=(const ConstantRange &CR) const {
 146     return !operator==(CR);
 147   }
 148
 149   /// subtract - Subtract the specified constant from the endpoints of this
 150   /// constant range.
 151   ConstantRange subtract(const APInt &CI) const;
 152
 153   /// intersectWith - Return the range that results from the intersection of
 154   /// this range with another range.  The resultant range is guaranteed to
 155   /// include all elements contained in both input ranges, and to have the
 156   /// smallest possible set size that does so.  Because there may be two
 157   /// intersections with the same set size, A.intersectWith(B) might not
 158   /// be equal to B.intersectWith(A).
 159   ///
 160   ConstantRange intersectWith(const ConstantRange &CR) const;
 161
 162   /// unionWith - Return the range that results from the union of this range
 163   /// with another range.  The resultant range is guaranteed to include the
 164   /// elements of both sets, but may contain more.  For example, [3, 9) union
 165   /// [12,15) is [3, 15), which includes 9, 10, and 11, which were not included
 166   /// in either set before.
 167   ///
 168   ConstantRange unionWith(const ConstantRange &CR) const;
 169
 170   /// zeroExtend - Return a new range in the specified integer type, which must
 171   /// be strictly larger than the current type.  The returned range will
 172   /// correspond to the possible range of values if the source range had been
 173   /// zero extended to BitWidth.
 174   ConstantRange zeroExtend(uint32_t BitWidth) const;
 175
 176   /// signExtend - Return a new range in the specified integer type, which must
 177   /// be strictly larger than the current type.  The returned range will
 178   /// correspond to the possible range of values if the source range had been
 179   /// sign extended to BitWidth.
 180   ConstantRange signExtend(uint32_t BitWidth) const;
 181
 182   /// truncate - Return a new range in the specified integer type, which must be
 183   /// strictly smaller than the current type.  The returned range will
 184   /// correspond to the possible range of values if the source range had been
 185   /// truncated to the specified type.
 186   ConstantRange truncate(uint32_t BitWidth) const;
 187
 188   /// zextOrTrunc - make this range have the bit width given by \p BitWidth. The
 189   /// value is zero extended, truncated, or left alone to make it that width.
 190   ConstantRange zextOrTrunc(uint32_t BitWidth) const;
 191
 192   /// sextOrTrunc - make this range have the bit width given by \p BitWidth. The
 193   /// value is sign extended, truncated, or left alone to make it that width.
 194   ConstantRange sextOrTrunc(uint32_t BitWidth) const;
 195
 196   /// add - Return a new range representing the possible values resulting
 197   /// from an addition of a value in this range and a value in \p Other.
 198   ConstantRange add(const ConstantRange &Other) const;
 199
 200   /// sub - Return a new range representing the possible values resulting
 201   /// from a subtraction of a value in this range and a value in \p Other.
 202   ConstantRange sub(const ConstantRange &Other) const;
 203
 204   /// multiply - Return a new range representing the possible values resulting
 205   /// from a multiplication of a value in this range and a value in \p Other.
 206   /// TODO: This isn't fully implemented yet.
 207   ConstantRange multiply(const ConstantRange &Other) const;
 208
 209   /// smax - Return a new range representing the possible values resulting
 210   /// from a signed maximum of a value in this range and a value in \p Other.
 211   ConstantRange smax(const ConstantRange &Other) const;
 212
 213   /// umax - Return a new range representing the possible values resulting
 214   /// from an unsigned maximum of a value in this range and a value in \p Other.
 215   ConstantRange umax(const ConstantRange &Other) const;
 216
 217   /// udiv - Return a new range representing the possible values resulting
 218   /// from an unsigned division of a value in this range and a value in
 219   /// \p Other.
 220   ConstantRange udiv(const ConstantRange &Other) const;
 221
 222   /// shl - Return a new range representing the possible values resulting
 223   /// from a left shift of a value in this range by a value in \p Other.
 224   /// TODO: This isn't fully implemented yet.
 225   ConstantRange shl(const ConstantRange &Other) const;
 226
 227   /// lshr - Return a new range representing the possible values resulting
 228   /// from a logical right shift of a value in this range and a value in
 229   /// \p Other.
 230   ConstantRange lshr(const ConstantRange &Other) const;
 231
 232   /// inverse - Return a new range that is the logical not of the current set.
 233   ///
 234   ConstantRange inverse() const;
 235
 236   /// print - Print out the bounds to a stream...
 237   ///
 238   void print(raw_ostream &OS) const;
 239
 240   /// dump - Allow printing from a debugger easily...
 241   ///
 242   void dump() const;
 243 };
 244
 245 inline raw_ostream &operator<<(raw_ostream &OS, const ConstantRange &CR) {
 246   CR.print(OS);
 247   return OS;
 248 }
 249
 250 } // End llvm namespace
 251
 252 #endif