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