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/Support/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   /// isSignWrappedSet - Return true if this set wraps around the INT_MIN of
  96   /// its bitwidth, for example: i8 [120, 140).
  97   ///
  98   bool isSignWrappedSet() const;
  99
 100   /// contains - Return true if the specified value is in the set.
 101   ///
 102   bool contains(const APInt &Val) const;
 103
 104   /// contains - Return true if the other range is a subset of this one.
 105   ///
 106   bool contains(const ConstantRange &CR) const;
 107
 108   /// getSingleElement - If this set contains a single element, return it,
 109   /// otherwise return null.
 110   ///
 111   const APInt *getSingleElement() const {
 112     if (Upper == Lower + 1)
 113       return &Lower;
 114     return 0;
 115   }
 116
 117   /// isSingleElement - Return true if this set contains exactly one member.
 118   ///
 119   bool isSingleElement() const { return getSingleElement() != 0; }
 120
 121   /// getSetSize - Return the number of elements in this set.
 122   ///
 123   APInt getSetSize() const;
 124
 125   /// getUnsignedMax - Return the largest unsigned value contained in the
 126   /// ConstantRange.
 127   ///
 128   APInt getUnsignedMax() const;
 129
 130   /// getUnsignedMin - Return the smallest unsigned value contained in the
 131   /// ConstantRange.
 132   ///
 133   APInt getUnsignedMin() const;
 134
 135   /// getSignedMax - Return the largest signed value contained in the
 136   /// ConstantRange.
 137   ///
 138   APInt getSignedMax() const;
 139
 140   /// getSignedMin - Return the smallest signed value contained in the
 141   /// ConstantRange.
 142   ///
 143   APInt getSignedMin() const;
 144
 145   /// operator== - Return true if this range is equal to another range.
 146   ///
 147   bool operator==(const ConstantRange &CR) const {
 148     return Lower == CR.Lower && Upper == CR.Upper;
 149   }
 150   bool operator!=(const ConstantRange &CR) const {
 151     return !operator==(CR);
 152   }
 153
 154   /// subtract - Subtract the specified constant from the endpoints of this
 155   /// constant range.
 156   ConstantRange subtract(const APInt &CI) const;
 157
 158   /// intersectWith - Return the range that results from the intersection of
 159   /// this range with another range.  The resultant range is guaranteed to
 160   /// include all elements contained in both input ranges, and to have the
 161   /// smallest possible set size that does so.  Because there may be two
 162   /// intersections with the same set size, A.intersectWith(B) might not
 163   /// be equal to B.intersectWith(A).
 164   ///
 165   ConstantRange intersectWith(const ConstantRange &CR) const;
 166
 167   /// unionWith - Return the range that results from the union of this range
 168   /// with another range.  The resultant range is guaranteed to include the
 169   /// elements of both sets, but may contain more.  For example, [3, 9) union
 170   /// [12,15) is [3, 15), which includes 9, 10, and 11, which were not included
 171   /// in either set before.
 172   ///
 173   ConstantRange unionWith(const ConstantRange &CR) const;
 174
 175   /// zeroExtend - Return a new range in the specified integer type, which must
 176   /// be strictly larger than the current type.  The returned range will
 177   /// correspond to the possible range of values if the source range had been
 178   /// zero extended to BitWidth.
 179   ConstantRange zeroExtend(uint32_t BitWidth) const;
 180
 181   /// signExtend - Return a new range in the specified integer type, which must
 182   /// be strictly larger than the current type.  The returned range will
 183   /// correspond to the possible range of values if the source range had been
 184   /// sign extended to BitWidth.
 185   ConstantRange signExtend(uint32_t BitWidth) const;
 186
 187   /// truncate - Return a new range in the specified integer type, which must be
 188   /// strictly smaller than the current type.  The returned range will
 189   /// correspond to the possible range of values if the source range had been
 190   /// truncated to the specified type.
 191   ConstantRange truncate(uint32_t BitWidth) const;
 192
 193   /// zextOrTrunc - make this range have the bit width given by \p BitWidth. The
 194   /// value is zero extended, truncated, or left alone to make it that width.
 195   ConstantRange zextOrTrunc(uint32_t BitWidth) const;
 196
 197   /// sextOrTrunc - make this range have the bit width given by \p BitWidth. The
 198   /// value is sign extended, truncated, or left alone to make it that width.
 199   ConstantRange sextOrTrunc(uint32_t BitWidth) const;
 200
 201   /// add - Return a new range representing the possible values resulting
 202   /// from an addition of a value in this range and a value in \p Other.
 203   ConstantRange add(const ConstantRange &Other) const;
 204
 205   /// sub - Return a new range representing the possible values resulting
 206   /// from a subtraction of a value in this range and a value in \p Other.
 207   ConstantRange sub(const ConstantRange &Other) const;
 208
 209   /// multiply - Return a new range representing the possible values resulting
 210   /// from a multiplication of a value in this range and a value in \p Other.
 211   /// TODO: This isn't fully implemented yet.
 212   ConstantRange multiply(const ConstantRange &Other) const;
 213
 214   /// smax - Return a new range representing the possible values resulting
 215   /// from a signed maximum of a value in this range and a value in \p Other.
 216   ConstantRange smax(const ConstantRange &Other) const;
 217
 218   /// umax - Return a new range representing the possible values resulting
 219   /// from an unsigned maximum of a value in this range and a value in \p Other.
 220   ConstantRange umax(const ConstantRange &Other) const;
 221
 222   /// udiv - Return a new range representing the possible values resulting
 223   /// from an unsigned division of a value in this range and a value in
 224   /// \p Other.
 225   ConstantRange udiv(const ConstantRange &Other) const;
 226
 227   /// binaryAnd - return a new range representing the possible values resulting
 228   /// from a binary-and of a value in this range by a value in \p Other.
 229   ConstantRange binaryAnd(const ConstantRange &Other) const;
 230
 231   /// binaryOr - return a new range representing the possible values resulting
 232   /// from a binary-or of a value in this range by a value in \p Other.
 233   ConstantRange binaryOr(const ConstantRange &Other) const;
 234
 235   /// shl - Return a new range representing the possible values resulting
 236   /// from a left shift of a value in this range by a value in \p Other.
 237   /// TODO: This isn't fully implemented yet.
 238   ConstantRange shl(const ConstantRange &Other) const;
 239
 240   /// lshr - Return a new range representing the possible values resulting
 241   /// from a logical right shift of a value in this range and a value in
 242   /// \p Other.
 243   ConstantRange lshr(const ConstantRange &Other) const;
 244
 245   /// inverse - Return a new range that is the logical not of the current set.
 246   ///
 247   ConstantRange inverse() const;
 248
 249   /// print - Print out the bounds to a stream...
 250   ///
 251   void print(raw_ostream &OS) const;
 252
 253   /// dump - Allow printing from a debugger easily...
 254   ///
 255   void dump() const;
 256 };
 257
 258 inline raw_ostream &operator<<(raw_ostream &OS, const ConstantRange &CR) {
 259   CR.print(OS);
 260   return OS;
 261 }
 262
 263 } // End llvm namespace
 264
 265 #endif