src/llvm/lib/IR/ConstantRange.cpp

   1 //===-- ConstantRange.cpp - ConstantRange implementation ------------------===//
   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 (other integral ranges use min/max values for special range values):
  16 //
  17 //  [F, F) = {}     = Empty set
  18 //  [T, F) = {T}
  19 //  [F, T) = {F}
  20 //  [T, T) = {F, T} = Full set
  21 //
  22 //===----------------------------------------------------------------------===//
  23
  24 #include "llvm/IR/InstrTypes.h"
  25 #include "llvm/IR/ConstantRange.h"
  26 #include "llvm/Support/Debug.h"
  27 #include "llvm/Support/raw_ostream.h"
  28 using namespace llvm;
  29
  30 /// Initialize a full (the default) or empty set for the specified type.
  31 ///
  32 ConstantRange::ConstantRange(uint32_t BitWidth, bool Full) {
  33   if (Full)
  34     Lower = Upper = APInt::getMaxValue(BitWidth);
  35   else
  36     Lower = Upper = APInt::getMinValue(BitWidth);
  37 }
  38
  39 /// Initialize a range to hold the single specified value.
  40 ///
  41 ConstantRange::ConstantRange(APIntMoveTy V)
  42     : Lower(std::move(V)), Upper(Lower + 1) {}
  43
  44 ConstantRange::ConstantRange(APIntMoveTy L, APIntMoveTy U)
  45     : Lower(std::move(L)), Upper(std::move(U)) {
  46   assert(Lower.getBitWidth() == Upper.getBitWidth() &&
  47          "ConstantRange with unequal bit widths");
  48   assert((Lower != Upper || (Lower.isMaxValue() || Lower.isMinValue())) &&
  49          "Lower == Upper, but they aren't min or max value!");
  50 }
  51
  52 ConstantRange ConstantRange::makeICmpRegion(unsigned Pred,
  53                                             const ConstantRange &CR) {
  54   if (CR.isEmptySet())
  55     return CR;
  56
  57   uint32_t W = CR.getBitWidth();
  58   switch (Pred) {
  59     default: llvm_unreachable("Invalid ICmp predicate to makeICmpRegion()");
  60     case CmpInst::ICMP_EQ:
  61       return CR;
  62     case CmpInst::ICMP_NE:
  63       if (CR.isSingleElement())
  64         return ConstantRange(CR.getUpper(), CR.getLower());
  65       return ConstantRange(W);
  66     case CmpInst::ICMP_ULT: {
  67       APInt UMax(CR.getUnsignedMax());
  68       if (UMax.isMinValue())
  69         return ConstantRange(W, /* empty */ false);
  70       return ConstantRange(APInt::getMinValue(W), UMax);
  71     }
  72     case CmpInst::ICMP_SLT: {
  73       APInt SMax(CR.getSignedMax());
  74       if (SMax.isMinSignedValue())
  75         return ConstantRange(W, /* empty */ false);
  76       return ConstantRange(APInt::getSignedMinValue(W), SMax);
  77     }
  78     case CmpInst::ICMP_ULE: {
  79       APInt UMax(CR.getUnsignedMax());
  80       if (UMax.isMaxValue())
  81         return ConstantRange(W);
  82       return ConstantRange(APInt::getMinValue(W), UMax + 1);
  83     }
  84     case CmpInst::ICMP_SLE: {
  85       APInt SMax(CR.getSignedMax());
  86       if (SMax.isMaxSignedValue())
  87         return ConstantRange(W);
  88       return ConstantRange(APInt::getSignedMinValue(W), SMax + 1);
  89     }
  90     case CmpInst::ICMP_UGT: {
  91       APInt UMin(CR.getUnsignedMin());
  92       if (UMin.isMaxValue())
  93         return ConstantRange(W, /* empty */ false);
  94       return ConstantRange(UMin + 1, APInt::getNullValue(W));
  95     }
  96     case CmpInst::ICMP_SGT: {
  97       APInt SMin(CR.getSignedMin());
  98       if (SMin.isMaxSignedValue())
  99         return ConstantRange(W, /* empty */ false);
 100       return ConstantRange(SMin + 1, APInt::getSignedMinValue(W));
 101     }
 102     case CmpInst::ICMP_UGE: {
 103       APInt UMin(CR.getUnsignedMin());
 104       if (UMin.isMinValue())
 105         return ConstantRange(W);
 106       return ConstantRange(UMin, APInt::getNullValue(W));
 107     }
 108     case CmpInst::ICMP_SGE: {
 109       APInt SMin(CR.getSignedMin());
 110       if (SMin.isMinSignedValue())
 111         return ConstantRange(W);
 112       return ConstantRange(SMin, APInt::getSignedMinValue(W));
 113     }
 114   }
 115 }
 116
 117 /// isFullSet - Return true if this set contains all of the elements possible
 118 /// for this data-type
 119 bool ConstantRange::isFullSet() const {
 120   return Lower == Upper && Lower.isMaxValue();
 121 }
 122
 123 /// isEmptySet - Return true if this set contains no members.
 124 ///
 125 bool ConstantRange::isEmptySet() const {
 126   return Lower == Upper && Lower.isMinValue();
 127 }
 128
 129 /// isWrappedSet - Return true if this set wraps around the top of the range,
 130 /// for example: [100, 8)
 131 ///
 132 bool ConstantRange::isWrappedSet() const {
 133   return Lower.ugt(Upper);
 134 }
 135
 136 /// isSignWrappedSet - Return true if this set wraps around the INT_MIN of
 137 /// its bitwidth, for example: i8 [120, 140).
 138 ///
 139 bool ConstantRange::isSignWrappedSet() const {
 140   return contains(APInt::getSignedMaxValue(getBitWidth())) &&
 141          contains(APInt::getSignedMinValue(getBitWidth()));
 142 }
 143
 144 /// getSetSize - Return the number of elements in this set.
 145 ///
 146 APInt ConstantRange::getSetSize() const {
 147   if (isFullSet()) {
 148     APInt Size(getBitWidth()+1, 0);
 149     Size.setBit(getBitWidth());
 150     return Size;
 151   }
 152
 153   // This is also correct for wrapped sets.
 154   return (Upper - Lower).zext(getBitWidth()+1);
 155 }
 156
 157 /// getUnsignedMax - Return the largest unsigned value contained in the
 158 /// ConstantRange.
 159 ///
 160 APInt ConstantRange::getUnsignedMax() const {
 161   if (isFullSet() || isWrappedSet())
 162     return APInt::getMaxValue(getBitWidth());
 163   return getUpper() - 1;
 164 }
 165
 166 /// getUnsignedMin - Return the smallest unsigned value contained in the
 167 /// ConstantRange.
 168 ///
 169 APInt ConstantRange::getUnsignedMin() const {
 170   if (isFullSet() || (isWrappedSet() && getUpper() != 0))
 171     return APInt::getMinValue(getBitWidth());
 172   return getLower();
 173 }
 174
 175 /// getSignedMax - Return the largest signed value contained in the
 176 /// ConstantRange.
 177 ///
 178 APInt ConstantRange::getSignedMax() const {
 179   APInt SignedMax(APInt::getSignedMaxValue(getBitWidth()));
 180   if (!isWrappedSet()) {
 181     if (getLower().sle(getUpper() - 1))
 182       return getUpper() - 1;
 183     return SignedMax;
 184   }
 185   if (getLower().isNegative() == getUpper().isNegative())
 186     return SignedMax;
 187   return getUpper() - 1;
 188 }
 189
 190 /// getSignedMin - Return the smallest signed value contained in the
 191 /// ConstantRange.
 192 ///
 193 APInt ConstantRange::getSignedMin() const {
 194   APInt SignedMin(APInt::getSignedMinValue(getBitWidth()));
 195   if (!isWrappedSet()) {
 196     if (getLower().sle(getUpper() - 1))
 197       return getLower();
 198     return SignedMin;
 199   }
 200   if ((getUpper() - 1).slt(getLower())) {
 201     if (getUpper() != SignedMin)
 202       return SignedMin;
 203   }
 204   return getLower();
 205 }
 206
 207 /// contains - Return true if the specified value is in the set.
 208 ///
 209 bool ConstantRange::contains(const APInt &V) const {
 210   if (Lower == Upper)
 211     return isFullSet();
 212
 213   if (!isWrappedSet())
 214     return Lower.ule(V) && V.ult(Upper);
 215   return Lower.ule(V) || V.ult(Upper);
 216 }
 217
 218 /// contains - Return true if the argument is a subset of this range.
 219 /// Two equal sets contain each other. The empty set contained by all other
 220 /// sets.
 221 ///
 222 bool ConstantRange::contains(const ConstantRange &Other) const {
 223   if (isFullSet() || Other.isEmptySet()) return true;
 224   if (isEmptySet() || Other.isFullSet()) return false;
 225
 226   if (!isWrappedSet()) {
 227     if (Other.isWrappedSet())
 228       return false;
 229
 230     return Lower.ule(Other.getLower()) && Other.getUpper().ule(Upper);
 231   }
 232
 233   if (!Other.isWrappedSet())
 234     return Other.getUpper().ule(Upper) ||
 235            Lower.ule(Other.getLower());
 236
 237   return Other.getUpper().ule(Upper) && Lower.ule(Other.getLower());
 238 }
 239
 240 /// subtract - Subtract the specified constant from the endpoints of this
 241 /// constant range.
 242 ConstantRange ConstantRange::subtract(const APInt &Val) const {
 243   assert(Val.getBitWidth() == getBitWidth() && "Wrong bit width");
 244   // If the set is empty or full, don't modify the endpoints.
 245   if (Lower == Upper)
 246     return *this;
 247   return ConstantRange(Lower - Val, Upper - Val);
 248 }
 249
 250 /// \brief Subtract the specified range from this range (aka relative complement
 251 /// of the sets).
 252 ConstantRange ConstantRange::difference(const ConstantRange &CR) const {
 253   return intersectWith(CR.inverse());
 254 }
 255
 256 /// intersectWith - Return the range that results from the intersection of this
 257 /// range with another range.  The resultant range is guaranteed to include all
 258 /// elements contained in both input ranges, and to have the smallest possible
 259 /// set size that does so.  Because there may be two intersections with the
 260 /// same set size, A.intersectWith(B) might not be equal to B.intersectWith(A).
 261 ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const {
 262   assert(getBitWidth() == CR.getBitWidth() &&
 263          "ConstantRange types don't agree!");
 264
 265   // Handle common cases.
 266   if (   isEmptySet() || CR.isFullSet()) return *this;
 267   if (CR.isEmptySet() ||    isFullSet()) return CR;
 268
 269   if (!isWrappedSet() && CR.isWrappedSet())
 270     return CR.intersectWith(*this);
 271
 272   if (!isWrappedSet() && !CR.isWrappedSet()) {
 273     if (Lower.ult(CR.Lower)) {
 274       if (Upper.ule(CR.Lower))
 275         return ConstantRange(getBitWidth(), false);
 276
 277       if (Upper.ult(CR.Upper))
 278         return ConstantRange(CR.Lower, Upper);
 279
 280       return CR;
 281     }
 282     if (Upper.ult(CR.Upper))
 283       return *this;
 284
 285     if (Lower.ult(CR.Upper))
 286       return ConstantRange(Lower, CR.Upper);
 287
 288     return ConstantRange(getBitWidth(), false);
 289   }
 290
 291   if (isWrappedSet() && !CR.isWrappedSet()) {
 292     if (CR.Lower.ult(Upper)) {
 293       if (CR.Upper.ult(Upper))
 294         return CR;
 295
 296       if (CR.Upper.ule(Lower))
 297         return ConstantRange(CR.Lower, Upper);
 298
 299       if (getSetSize().ult(CR.getSetSize()))
 300         return *this;
 301       return CR;
 302     }
 303     if (CR.Lower.ult(Lower)) {
 304       if (CR.Upper.ule(Lower))
 305         return ConstantRange(getBitWidth(), false);
 306
 307       return ConstantRange(Lower, CR.Upper);
 308     }
 309     return CR;
 310   }
 311
 312   if (CR.Upper.ult(Upper)) {
 313     if (CR.Lower.ult(Upper)) {
 314       if (getSetSize().ult(CR.getSetSize()))
 315         return *this;
 316       return CR;
 317     }
 318
 319     if (CR.Lower.ult(Lower))
 320       return ConstantRange(Lower, CR.Upper);
 321
 322     return CR;
 323   }
 324   if (CR.Upper.ule(Lower)) {
 325     if (CR.Lower.ult(Lower))
 326       return *this;
 327
 328     return ConstantRange(CR.Lower, Upper);
 329   }
 330   if (getSetSize().ult(CR.getSetSize()))
 331     return *this;
 332   return CR;
 333 }
 334
 335
 336 /// unionWith - Return the range that results from the union of this range with
 337 /// another range.  The resultant range is guaranteed to include the elements of
 338 /// both sets, but may contain more.  For example, [3, 9) union [12,15) is
 339 /// [3, 15), which includes 9, 10, and 11, which were not included in either
 340 /// set before.
 341 ///
 342 ConstantRange ConstantRange::unionWith(const ConstantRange &CR) const {
 343   assert(getBitWidth() == CR.getBitWidth() &&
 344          "ConstantRange types don't agree!");
 345
 346   if (   isFullSet() || CR.isEmptySet()) return *this;
 347   if (CR.isFullSet() ||    isEmptySet()) return CR;
 348
 349   if (!isWrappedSet() && CR.isWrappedSet()) return CR.unionWith(*this);
 350
 351   if (!isWrappedSet() && !CR.isWrappedSet()) {
 352     if (CR.Upper.ult(Lower) || Upper.ult(CR.Lower)) {
 353       // If the two ranges are disjoint, find the smaller gap and bridge it.
 354       APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Upper;
 355       if (d1.ult(d2))
 356         return ConstantRange(Lower, CR.Upper);
 357       return ConstantRange(CR.Lower, Upper);
 358     }
 359
 360     APInt L = Lower, U = Upper;
 361     if (CR.Lower.ult(L))
 362       L = CR.Lower;
 363     if ((CR.Upper - 1).ugt(U - 1))
 364       U = CR.Upper;
 365
 366     if (L == 0 && U == 0)
 367       return ConstantRange(getBitWidth());
 368
 369     return ConstantRange(L, U);
 370   }
 371
 372   if (!CR.isWrappedSet()) {
 373     // ------U   L-----  and  ------U   L----- : this
 374     //   L--U                            L--U  : CR
 375     if (CR.Upper.ule(Upper) || CR.Lower.uge(Lower))
 376       return *this;
 377
 378     // ------U   L----- : this
 379     //    L---------U   : CR
 380     if (CR.Lower.ule(Upper) && Lower.ule(CR.Upper))
 381       return ConstantRange(getBitWidth());
 382
 383     // ----U       L---- : this
 384     //       L---U       : CR
 385     //    <d1>  <d2>
 386     if (Upper.ule(CR.Lower) && CR.Upper.ule(Lower)) {
 387       APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Upper;
 388       if (d1.ult(d2))
 389         return ConstantRange(Lower, CR.Upper);
 390       return ConstantRange(CR.Lower, Upper);
 391     }
 392
 393     // ----U     L----- : this
 394     //        L----U    : CR
 395     if (Upper.ult(CR.Lower) && Lower.ult(CR.Upper))
 396       return ConstantRange(CR.Lower, Upper);
 397
 398     // ------U    L---- : this
 399     //    L-----U       : CR
 400     assert(CR.Lower.ult(Upper) && CR.Upper.ult(Lower) &&
 401            "ConstantRange::unionWith missed a case with one range wrapped");
 402     return ConstantRange(Lower, CR.Upper);
 403   }
 404
 405   // ------U    L----  and  ------U    L---- : this
 406   // -U  L-----------  and  ------------U  L : CR
 407   if (CR.Lower.ule(Upper) || Lower.ule(CR.Upper))
 408     return ConstantRange(getBitWidth());
 409
 410   APInt L = Lower, U = Upper;
 411   if (CR.Upper.ugt(U))
 412     U = CR.Upper;
 413   if (CR.Lower.ult(L))
 414     L = CR.Lower;
 415
 416   return ConstantRange(L, U);
 417 }
 418
 419 /// zeroExtend - Return a new range in the specified integer type, which must
 420 /// be strictly larger than the current type.  The returned range will
 421 /// correspond to the possible range of values as if the source range had been
 422 /// zero extended.
 423 ConstantRange ConstantRange::zeroExtend(uint32_t DstTySize) const {
 424   if (isEmptySet()) return ConstantRange(DstTySize, /*isFullSet=*/false);
 425
 426   unsigned SrcTySize = getBitWidth();
 427   assert(SrcTySize < DstTySize && "Not a value extension");
 428   if (isFullSet() || isWrappedSet()) {
 429     // Change into [0, 1 << src bit width)
 430     APInt LowerExt(DstTySize, 0);
 431     if (!Upper) // special case: [X, 0) -- not really wrapping around
 432       LowerExt = Lower.zext(DstTySize);
 433     return ConstantRange(LowerExt, APInt::getOneBitSet(DstTySize, SrcTySize));
 434   }
 435
 436   return ConstantRange(Lower.zext(DstTySize), Upper.zext(DstTySize));
 437 }
 438
 439 /// signExtend - Return a new range in the specified integer type, which must
 440 /// be strictly larger than the current type.  The returned range will
 441 /// correspond to the possible range of values as if the source range had been
 442 /// sign extended.
 443 ConstantRange ConstantRange::signExtend(uint32_t DstTySize) const {
 444   if (isEmptySet()) return ConstantRange(DstTySize, /*isFullSet=*/false);
 445
 446   unsigned SrcTySize = getBitWidth();
 447   assert(SrcTySize < DstTySize && "Not a value extension");
 448
 449   // special case: [X, INT_MIN) -- not really wrapping around
 450   if (Upper.isMinSignedValue())
 451     return ConstantRange(Lower.sext(DstTySize), Upper.zext(DstTySize));
 452
 453   if (isFullSet() || isSignWrappedSet()) {
 454     return ConstantRange(APInt::getHighBitsSet(DstTySize,DstTySize-SrcTySize+1),
 455                          APInt::getLowBitsSet(DstTySize, SrcTySize-1) + 1);
 456   }
 457
 458   return ConstantRange(Lower.sext(DstTySize), Upper.sext(DstTySize));
 459 }
 460
 461 /// truncate - Return a new range in the specified integer type, which must be
 462 /// strictly smaller than the current type.  The returned range will
 463 /// correspond to the possible range of values as if the source range had been
 464 /// truncated to the specified type.
 465 ConstantRange ConstantRange::truncate(uint32_t DstTySize) const {
 466   assert(getBitWidth() > DstTySize && "Not a value truncation");
 467   if (isEmptySet())
 468     return ConstantRange(DstTySize, /*isFullSet=*/false);
 469   if (isFullSet())
 470     return ConstantRange(DstTySize, /*isFullSet=*/true);
 471
 472   APInt MaxValue = APInt::getMaxValue(DstTySize).zext(getBitWidth());
 473   APInt MaxBitValue(getBitWidth(), 0);
 474   MaxBitValue.setBit(DstTySize);
 475
 476   APInt LowerDiv(Lower), UpperDiv(Upper);
 477   ConstantRange Union(DstTySize, /*isFullSet=*/false);
 478
 479   // Analyze wrapped sets in their two parts: [0, Upper) \/ [Lower, MaxValue]
 480   // We use the non-wrapped set code to analyze the [Lower, MaxValue) part, and
 481   // then we do the union with [MaxValue, Upper)
 482   if (isWrappedSet()) {
 483     // if Upper is greater than Max Value, it covers the whole truncated range.
 484     if (Upper.uge(MaxValue))
 485       return ConstantRange(DstTySize, /*isFullSet=*/true);
 486
 487     Union = ConstantRange(APInt::getMaxValue(DstTySize),Upper.trunc(DstTySize));
 488     UpperDiv = APInt::getMaxValue(getBitWidth());
 489
 490     // Union covers the MaxValue case, so return if the remaining range is just
 491     // MaxValue.
 492     if (LowerDiv == UpperDiv)
 493       return Union;
 494   }
 495
 496   // Chop off the most significant bits that are past the destination bitwidth.
 497   if (LowerDiv.uge(MaxValue)) {
 498     APInt Div(getBitWidth(), 0);
 499     APInt::udivrem(LowerDiv, MaxBitValue, Div, LowerDiv);
 500     UpperDiv = UpperDiv - MaxBitValue * Div;
 501   }
 502
 503   if (UpperDiv.ule(MaxValue))
 504     return ConstantRange(LowerDiv.trunc(DstTySize),
 505                          UpperDiv.trunc(DstTySize)).unionWith(Union);
 506
 507   // The truncated value wrapps around. Check if we can do better than fullset.
 508   APInt UpperModulo = UpperDiv - MaxBitValue;
 509   if (UpperModulo.ult(LowerDiv))
 510     return ConstantRange(LowerDiv.trunc(DstTySize),
 511                          UpperModulo.trunc(DstTySize)).unionWith(Union);
 512
 513   return ConstantRange(DstTySize, /*isFullSet=*/true);
 514 }
 515
 516 /// zextOrTrunc - make this range have the bit width given by \p DstTySize. The
 517 /// value is zero extended, truncated, or left alone to make it that width.
 518 ConstantRange ConstantRange::zextOrTrunc(uint32_t DstTySize) const {
 519   unsigned SrcTySize = getBitWidth();
 520   if (SrcTySize > DstTySize)
 521     return truncate(DstTySize);
 522   if (SrcTySize < DstTySize)
 523     return zeroExtend(DstTySize);
 524   return *this;
 525 }
 526
 527 /// sextOrTrunc - make this range have the bit width given by \p DstTySize. The
 528 /// value is sign extended, truncated, or left alone to make it that width.
 529 ConstantRange ConstantRange::sextOrTrunc(uint32_t DstTySize) const {
 530   unsigned SrcTySize = getBitWidth();
 531   if (SrcTySize > DstTySize)
 532     return truncate(DstTySize);
 533   if (SrcTySize < DstTySize)
 534     return signExtend(DstTySize);
 535   return *this;
 536 }
 537
 538 ConstantRange
 539 ConstantRange::add(const ConstantRange &Other) const {
 540   if (isEmptySet() || Other.isEmptySet())
 541     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
 542   if (isFullSet() || Other.isFullSet())
 543     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 544
 545   APInt Spread_X = getSetSize(), Spread_Y = Other.getSetSize();
 546   APInt NewLower = getLower() + Other.getLower();
 547   APInt NewUpper = getUpper() + Other.getUpper() - 1;
 548   if (NewLower == NewUpper)
 549     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 550
 551   ConstantRange X = ConstantRange(NewLower, NewUpper);
 552   if (X.getSetSize().ult(Spread_X) || X.getSetSize().ult(Spread_Y))
 553     // We've wrapped, therefore, full set.
 554     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 555
 556   return X;
 557 }
 558
 559 ConstantRange
 560 ConstantRange::sub(const ConstantRange &Other) const {
 561   if (isEmptySet() || Other.isEmptySet())
 562     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
 563   if (isFullSet() || Other.isFullSet())
 564     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 565
 566   APInt Spread_X = getSetSize(), Spread_Y = Other.getSetSize();
 567   APInt NewLower = getLower() - Other.getUpper() + 1;
 568   APInt NewUpper = getUpper() - Other.getLower();
 569   if (NewLower == NewUpper)
 570     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 571
 572   ConstantRange X = ConstantRange(NewLower, NewUpper);
 573   if (X.getSetSize().ult(Spread_X) || X.getSetSize().ult(Spread_Y))
 574     // We've wrapped, therefore, full set.
 575     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 576
 577   return X;
 578 }
 579
 580 ConstantRange
 581 ConstantRange::multiply(const ConstantRange &Other) const {
 582   // TODO: If either operand is a single element and the multiply is known to
 583   // be non-wrapping, round the result min and max value to the appropriate
 584   // multiple of that element. If wrapping is possible, at least adjust the
 585   // range according to the greatest power-of-two factor of the single element.
 586
 587   if (isEmptySet() || Other.isEmptySet())
 588     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
 589
 590   APInt this_min = getUnsignedMin().zext(getBitWidth() * 2);
 591   APInt this_max = getUnsignedMax().zext(getBitWidth() * 2);
 592   APInt Other_min = Other.getUnsignedMin().zext(getBitWidth() * 2);
 593   APInt Other_max = Other.getUnsignedMax().zext(getBitWidth() * 2);
 594
 595   ConstantRange Result_zext = ConstantRange(this_min * Other_min,
 596                                             this_max * Other_max + 1);
 597   return Result_zext.truncate(getBitWidth());
 598 }
 599
 600 ConstantRange
 601 ConstantRange::smax(const ConstantRange &Other) const {
 602   // X smax Y is: range(smax(X_smin, Y_smin),
 603   //                    smax(X_smax, Y_smax))
 604   if (isEmptySet() || Other.isEmptySet())
 605     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
 606   APInt NewL = APIntOps::smax(getSignedMin(), Other.getSignedMin());
 607   APInt NewU = APIntOps::smax(getSignedMax(), Other.getSignedMax()) + 1;
 608   if (NewU == NewL)
 609     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 610   return ConstantRange(NewL, NewU);
 611 }
 612
 613 ConstantRange
 614 ConstantRange::umax(const ConstantRange &Other) const {
 615   // X umax Y is: range(umax(X_umin, Y_umin),
 616   //                    umax(X_umax, Y_umax))
 617   if (isEmptySet() || Other.isEmptySet())
 618     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
 619   APInt NewL = APIntOps::umax(getUnsignedMin(), Other.getUnsignedMin());
 620   APInt NewU = APIntOps::umax(getUnsignedMax(), Other.getUnsignedMax()) + 1;
 621   if (NewU == NewL)
 622     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 623   return ConstantRange(NewL, NewU);
 624 }
 625
 626 ConstantRange
 627 ConstantRange::udiv(const ConstantRange &RHS) const {
 628   if (isEmptySet() || RHS.isEmptySet() || RHS.getUnsignedMax() == 0)
 629     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
 630   if (RHS.isFullSet())
 631     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 632
 633   APInt Lower = getUnsignedMin().udiv(RHS.getUnsignedMax());
 634
 635   APInt RHS_umin = RHS.getUnsignedMin();
 636   if (RHS_umin == 0) {
 637     // We want the lowest value in RHS excluding zero. Usually that would be 1
 638     // except for a range in the form of [X, 1) in which case it would be X.
 639     if (RHS.getUpper() == 1)
 640       RHS_umin = RHS.getLower();
 641     else
 642       RHS_umin = APInt(getBitWidth(), 1);
 643   }
 644
 645   APInt Upper = getUnsignedMax().udiv(RHS_umin) + 1;
 646
 647   // If the LHS is Full and the RHS is a wrapped interval containing 1 then
 648   // this could occur.
 649   if (Lower == Upper)
 650     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 651
 652   return ConstantRange(Lower, Upper);
 653 }
 654
 655 ConstantRange
 656 ConstantRange::binaryAnd(const ConstantRange &Other) const {
 657   if (isEmptySet() || Other.isEmptySet())
 658     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
 659
 660   // TODO: replace this with something less conservative
 661
 662   APInt umin = APIntOps::umin(Other.getUnsignedMax(), getUnsignedMax());
 663   if (umin.isAllOnesValue())
 664     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 665   return ConstantRange(APInt::getNullValue(getBitWidth()), umin + 1);
 666 }
 667
 668 ConstantRange
 669 ConstantRange::binaryOr(const ConstantRange &Other) const {
 670   if (isEmptySet() || Other.isEmptySet())
 671     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
 672
 673   // TODO: replace this with something less conservative
 674
 675   APInt umax = APIntOps::umax(getUnsignedMin(), Other.getUnsignedMin());
 676   if (umax.isMinValue())
 677     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 678   return ConstantRange(umax, APInt::getNullValue(getBitWidth()));
 679 }
 680
 681 ConstantRange
 682 ConstantRange::shl(const ConstantRange &Other) const {
 683   if (isEmptySet() || Other.isEmptySet())
 684     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
 685
 686   APInt min = getUnsignedMin().shl(Other.getUnsignedMin());
 687   APInt max = getUnsignedMax().shl(Other.getUnsignedMax());
 688
 689   // there's no overflow!
 690   APInt Zeros(getBitWidth(), getUnsignedMax().countLeadingZeros());
 691   if (Zeros.ugt(Other.getUnsignedMax()))
 692     return ConstantRange(min, max + 1);
 693
 694   // FIXME: implement the other tricky cases
 695   return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 696 }
 697
 698 ConstantRange
 699 ConstantRange::lshr(const ConstantRange &Other) const {
 700   if (isEmptySet() || Other.isEmptySet())
 701     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
 702
 703   APInt max = getUnsignedMax().lshr(Other.getUnsignedMin());
 704   APInt min = getUnsignedMin().lshr(Other.getUnsignedMax());
 705   if (min == max + 1)
 706     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 707
 708   return ConstantRange(min, max + 1);
 709 }
 710
 711 ConstantRange ConstantRange::inverse() const {
 712   if (isFullSet())
 713     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
 714   if (isEmptySet())
 715     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 716   return ConstantRange(Upper, Lower);
 717 }
 718
 719 /// print - Print out the bounds to a stream...
 720 ///
 721 void ConstantRange::print(raw_ostream &OS) const {
 722   if (isFullSet())
 723     OS << "full-set";
 724   else if (isEmptySet())
 725     OS << "empty-set";
 726   else
 727     OS << "[" << Lower << "," << Upper << ")";
 728 }
 729
 730 /// dump - Allow printing from a debugger easily...
 731 ///
 732 void ConstantRange::dump() const {
 733   print(dbgs());
 734 }