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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/InstrTypes.h"
25 #include "llvm/Support/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 ///
ConstantRange(uint32_t BitWidth,bool Full)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 ///
ConstantRange(const APInt & V)41 ConstantRange::ConstantRange(const APInt &V) : Lower(V), Upper(V + 1) {}
42 
ConstantRange(const APInt & L,const APInt & U)43 ConstantRange::ConstantRange(const APInt &L, const APInt &U) :
44   Lower(L), Upper(U) {
45   assert(L.getBitWidth() == U.getBitWidth() &&
46          "ConstantRange with unequal bit widths");
47   assert((L != U || (L.isMaxValue() || L.isMinValue())) &&
48          "Lower == Upper, but they aren't min or max value!");
49 }
50 
makeICmpRegion(unsigned Pred,const ConstantRange & CR)51 ConstantRange ConstantRange::makeICmpRegion(unsigned Pred,
52                                             const ConstantRange &CR) {
53   if (CR.isEmptySet())
54     return CR;
55 
56   uint32_t W = CR.getBitWidth();
57   switch (Pred) {
58     default: assert(0 && "Invalid ICmp predicate to makeICmpRegion()");
59     case CmpInst::ICMP_EQ:
60       return CR;
61     case CmpInst::ICMP_NE:
62       if (CR.isSingleElement())
63         return ConstantRange(CR.getUpper(), CR.getLower());
64       return ConstantRange(W);
65     case CmpInst::ICMP_ULT: {
66       APInt UMax(CR.getUnsignedMax());
67       if (UMax.isMinValue())
68         return ConstantRange(W, /* empty */ false);
69       return ConstantRange(APInt::getMinValue(W), UMax);
70     }
71     case CmpInst::ICMP_SLT: {
72       APInt SMax(CR.getSignedMax());
73       if (SMax.isMinSignedValue())
74         return ConstantRange(W, /* empty */ false);
75       return ConstantRange(APInt::getSignedMinValue(W), SMax);
76     }
77     case CmpInst::ICMP_ULE: {
78       APInt UMax(CR.getUnsignedMax());
79       if (UMax.isMaxValue())
80         return ConstantRange(W);
81       return ConstantRange(APInt::getMinValue(W), UMax + 1);
82     }
83     case CmpInst::ICMP_SLE: {
84       APInt SMax(CR.getSignedMax());
85       if (SMax.isMaxSignedValue())
86         return ConstantRange(W);
87       return ConstantRange(APInt::getSignedMinValue(W), SMax + 1);
88     }
89     case CmpInst::ICMP_UGT: {
90       APInt UMin(CR.getUnsignedMin());
91       if (UMin.isMaxValue())
92         return ConstantRange(W, /* empty */ false);
93       return ConstantRange(UMin + 1, APInt::getNullValue(W));
94     }
95     case CmpInst::ICMP_SGT: {
96       APInt SMin(CR.getSignedMin());
97       if (SMin.isMaxSignedValue())
98         return ConstantRange(W, /* empty */ false);
99       return ConstantRange(SMin + 1, APInt::getSignedMinValue(W));
100     }
101     case CmpInst::ICMP_UGE: {
102       APInt UMin(CR.getUnsignedMin());
103       if (UMin.isMinValue())
104         return ConstantRange(W);
105       return ConstantRange(UMin, APInt::getNullValue(W));
106     }
107     case CmpInst::ICMP_SGE: {
108       APInt SMin(CR.getSignedMin());
109       if (SMin.isMinSignedValue())
110         return ConstantRange(W);
111       return ConstantRange(SMin, APInt::getSignedMinValue(W));
112     }
113   }
114 }
115 
116 /// isFullSet - Return true if this set contains all of the elements possible
117 /// for this data-type
isFullSet() const118 bool ConstantRange::isFullSet() const {
119   return Lower == Upper && Lower.isMaxValue();
120 }
121 
122 /// isEmptySet - Return true if this set contains no members.
123 ///
isEmptySet() const124 bool ConstantRange::isEmptySet() const {
125   return Lower == Upper && Lower.isMinValue();
126 }
127 
128 /// isWrappedSet - Return true if this set wraps around the top of the range,
129 /// for example: [100, 8)
130 ///
isWrappedSet() const131 bool ConstantRange::isWrappedSet() const {
132   return Lower.ugt(Upper);
133 }
134 
135 /// isSignWrappedSet - Return true if this set wraps around the INT_MIN of
136 /// its bitwidth, for example: i8 [120, 140).
137 ///
isSignWrappedSet() const138 bool ConstantRange::isSignWrappedSet() const {
139   return contains(APInt::getSignedMaxValue(getBitWidth())) &&
140          contains(APInt::getSignedMinValue(getBitWidth()));
141 }
142 
143 /// getSetSize - Return the number of elements in this set.
144 ///
getSetSize() const145 APInt ConstantRange::getSetSize() const {
146   if (isEmptySet())
147     return APInt(getBitWidth(), 0);
148   if (getBitWidth() == 1) {
149     if (Lower != Upper)  // One of T or F in the set...
150       return APInt(2, 1);
151     return APInt(2, 2);      // Must be full set...
152   }
153 
154   // Simply subtract the bounds...
155   return Upper - Lower;
156 }
157 
158 /// getUnsignedMax - Return the largest unsigned value contained in the
159 /// ConstantRange.
160 ///
getUnsignedMax() const161 APInt ConstantRange::getUnsignedMax() const {
162   if (isFullSet() || isWrappedSet())
163     return APInt::getMaxValue(getBitWidth());
164   else
165     return getUpper() - 1;
166 }
167 
168 /// getUnsignedMin - Return the smallest unsigned value contained in the
169 /// ConstantRange.
170 ///
getUnsignedMin() const171 APInt ConstantRange::getUnsignedMin() const {
172   if (isFullSet() || (isWrappedSet() && getUpper() != 0))
173     return APInt::getMinValue(getBitWidth());
174   else
175     return getLower();
176 }
177 
178 /// getSignedMax - Return the largest signed value contained in the
179 /// ConstantRange.
180 ///
getSignedMax() const181 APInt ConstantRange::getSignedMax() const {
182   APInt SignedMax(APInt::getSignedMaxValue(getBitWidth()));
183   if (!isWrappedSet()) {
184     if (getLower().sle(getUpper() - 1))
185       return getUpper() - 1;
186     else
187       return SignedMax;
188   } else {
189     if (getLower().isNegative() == getUpper().isNegative())
190       return SignedMax;
191     else
192       return getUpper() - 1;
193   }
194 }
195 
196 /// getSignedMin - Return the smallest signed value contained in the
197 /// ConstantRange.
198 ///
getSignedMin() const199 APInt ConstantRange::getSignedMin() const {
200   APInt SignedMin(APInt::getSignedMinValue(getBitWidth()));
201   if (!isWrappedSet()) {
202     if (getLower().sle(getUpper() - 1))
203       return getLower();
204     else
205       return SignedMin;
206   } else {
207     if ((getUpper() - 1).slt(getLower())) {
208       if (getUpper() != SignedMin)
209         return SignedMin;
210       else
211         return getLower();
212     } else {
213       return getLower();
214     }
215   }
216 }
217 
218 /// contains - Return true if the specified value is in the set.
219 ///
contains(const APInt & V) const220 bool ConstantRange::contains(const APInt &V) const {
221   if (Lower == Upper)
222     return isFullSet();
223 
224   if (!isWrappedSet())
225     return Lower.ule(V) && V.ult(Upper);
226   else
227     return Lower.ule(V) || V.ult(Upper);
228 }
229 
230 /// contains - Return true if the argument is a subset of this range.
231 /// Two equal sets contain each other. The empty set contained by all other
232 /// sets.
233 ///
contains(const ConstantRange & Other) const234 bool ConstantRange::contains(const ConstantRange &Other) const {
235   if (isFullSet() || Other.isEmptySet()) return true;
236   if (isEmptySet() || Other.isFullSet()) return false;
237 
238   if (!isWrappedSet()) {
239     if (Other.isWrappedSet())
240       return false;
241 
242     return Lower.ule(Other.getLower()) && Other.getUpper().ule(Upper);
243   }
244 
245   if (!Other.isWrappedSet())
246     return Other.getUpper().ule(Upper) ||
247            Lower.ule(Other.getLower());
248 
249   return Other.getUpper().ule(Upper) && Lower.ule(Other.getLower());
250 }
251 
252 /// subtract - Subtract the specified constant from the endpoints of this
253 /// constant range.
subtract(const APInt & Val) const254 ConstantRange ConstantRange::subtract(const APInt &Val) const {
255   assert(Val.getBitWidth() == getBitWidth() && "Wrong bit width");
256   // If the set is empty or full, don't modify the endpoints.
257   if (Lower == Upper)
258     return *this;
259   return ConstantRange(Lower - Val, Upper - Val);
260 }
261 
262 /// intersectWith - Return the range that results from the intersection of this
263 /// range with another range.  The resultant range is guaranteed to include all
264 /// elements contained in both input ranges, and to have the smallest possible
265 /// set size that does so.  Because there may be two intersections with the
266 /// same set size, A.intersectWith(B) might not be equal to B.intersectWith(A).
intersectWith(const ConstantRange & CR) const267 ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const {
268   assert(getBitWidth() == CR.getBitWidth() &&
269          "ConstantRange types don't agree!");
270 
271   // Handle common cases.
272   if (   isEmptySet() || CR.isFullSet()) return *this;
273   if (CR.isEmptySet() ||    isFullSet()) return CR;
274 
275   if (!isWrappedSet() && CR.isWrappedSet())
276     return CR.intersectWith(*this);
277 
278   if (!isWrappedSet() && !CR.isWrappedSet()) {
279     if (Lower.ult(CR.Lower)) {
280       if (Upper.ule(CR.Lower))
281         return ConstantRange(getBitWidth(), false);
282 
283       if (Upper.ult(CR.Upper))
284         return ConstantRange(CR.Lower, Upper);
285 
286       return CR;
287     } else {
288       if (Upper.ult(CR.Upper))
289         return *this;
290 
291       if (Lower.ult(CR.Upper))
292         return ConstantRange(Lower, CR.Upper);
293 
294       return ConstantRange(getBitWidth(), false);
295     }
296   }
297 
298   if (isWrappedSet() && !CR.isWrappedSet()) {
299     if (CR.Lower.ult(Upper)) {
300       if (CR.Upper.ult(Upper))
301         return CR;
302 
303       if (CR.Upper.ult(Lower))
304         return ConstantRange(CR.Lower, Upper);
305 
306       if (getSetSize().ult(CR.getSetSize()))
307         return *this;
308       else
309         return CR;
310     } else if (CR.Lower.ult(Lower)) {
311       if (CR.Upper.ule(Lower))
312         return ConstantRange(getBitWidth(), false);
313 
314       return ConstantRange(Lower, CR.Upper);
315     }
316     return CR;
317   }
318 
319   if (CR.Upper.ult(Upper)) {
320     if (CR.Lower.ult(Upper)) {
321       if (getSetSize().ult(CR.getSetSize()))
322         return *this;
323       else
324         return CR;
325     }
326 
327     if (CR.Lower.ult(Lower))
328       return ConstantRange(Lower, CR.Upper);
329 
330     return CR;
331   } else if (CR.Upper.ult(Lower)) {
332     if (CR.Lower.ult(Lower))
333       return *this;
334 
335     return ConstantRange(CR.Lower, Upper);
336   }
337   if (getSetSize().ult(CR.getSetSize()))
338     return *this;
339   else
340     return CR;
341 }
342 
343 
344 /// unionWith - Return the range that results from the union of this range with
345 /// another range.  The resultant range is guaranteed to include the elements of
346 /// both sets, but may contain more.  For example, [3, 9) union [12,15) is
347 /// [3, 15), which includes 9, 10, and 11, which were not included in either
348 /// set before.
349 ///
unionWith(const ConstantRange & CR) const350 ConstantRange ConstantRange::unionWith(const ConstantRange &CR) const {
351   assert(getBitWidth() == CR.getBitWidth() &&
352          "ConstantRange types don't agree!");
353 
354   if (   isFullSet() || CR.isEmptySet()) return *this;
355   if (CR.isFullSet() ||    isEmptySet()) return CR;
356 
357   if (!isWrappedSet() && CR.isWrappedSet()) return CR.unionWith(*this);
358 
359   if (!isWrappedSet() && !CR.isWrappedSet()) {
360     if (CR.Upper.ult(Lower) || Upper.ult(CR.Lower)) {
361       // If the two ranges are disjoint, find the smaller gap and bridge it.
362       APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Upper;
363       if (d1.ult(d2))
364         return ConstantRange(Lower, CR.Upper);
365       else
366         return ConstantRange(CR.Lower, Upper);
367     }
368 
369     APInt L = Lower, U = Upper;
370     if (CR.Lower.ult(L))
371       L = CR.Lower;
372     if ((CR.Upper - 1).ugt(U - 1))
373       U = CR.Upper;
374 
375     if (L == 0 && U == 0)
376       return ConstantRange(getBitWidth());
377 
378     return ConstantRange(L, U);
379   }
380 
381   if (!CR.isWrappedSet()) {
382     // ------U   L-----  and  ------U   L----- : this
383     //   L--U                            L--U  : CR
384     if (CR.Upper.ule(Upper) || CR.Lower.uge(Lower))
385       return *this;
386 
387     // ------U   L----- : this
388     //    L---------U   : CR
389     if (CR.Lower.ule(Upper) && Lower.ule(CR.Upper))
390       return ConstantRange(getBitWidth());
391 
392     // ----U       L---- : this
393     //       L---U       : CR
394     //    <d1>  <d2>
395     if (Upper.ule(CR.Lower) && CR.Upper.ule(Lower)) {
396       APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Upper;
397       if (d1.ult(d2))
398         return ConstantRange(Lower, CR.Upper);
399       else
400         return ConstantRange(CR.Lower, Upper);
401     }
402 
403     // ----U     L----- : this
404     //        L----U    : CR
405     if (Upper.ult(CR.Lower) && Lower.ult(CR.Upper))
406       return ConstantRange(CR.Lower, Upper);
407 
408     // ------U    L---- : this
409     //    L-----U       : CR
410     if (CR.Lower.ult(Upper) && CR.Upper.ult(Lower))
411       return ConstantRange(Lower, CR.Upper);
412   }
413 
414   assert(isWrappedSet() && CR.isWrappedSet() &&
415          "ConstantRange::unionWith missed wrapped union unwrapped case");
416 
417   // ------U    L----  and  ------U    L---- : this
418   // -U  L-----------  and  ------------U  L : CR
419   if (CR.Lower.ule(Upper) || Lower.ule(CR.Upper))
420     return ConstantRange(getBitWidth());
421 
422   APInt L = Lower, U = Upper;
423   if (CR.Upper.ugt(U))
424     U = CR.Upper;
425   if (CR.Lower.ult(L))
426     L = CR.Lower;
427 
428   return ConstantRange(L, U);
429 }
430 
431 /// zeroExtend - Return a new range in the specified integer type, which must
432 /// be strictly larger than the current type.  The returned range will
433 /// correspond to the possible range of values as if the source range had been
434 /// zero extended.
zeroExtend(uint32_t DstTySize) const435 ConstantRange ConstantRange::zeroExtend(uint32_t DstTySize) const {
436   if (isEmptySet()) return ConstantRange(DstTySize, /*isFullSet=*/false);
437 
438   unsigned SrcTySize = getBitWidth();
439   assert(SrcTySize < DstTySize && "Not a value extension");
440   if (isFullSet() || isWrappedSet())
441     // Change into [0, 1 << src bit width)
442     return ConstantRange(APInt(DstTySize,0), APInt(DstTySize,1).shl(SrcTySize));
443 
444   return ConstantRange(Lower.zext(DstTySize), Upper.zext(DstTySize));
445 }
446 
447 /// signExtend - Return a new range in the specified integer type, which must
448 /// be strictly larger than the current type.  The returned range will
449 /// correspond to the possible range of values as if the source range had been
450 /// sign extended.
signExtend(uint32_t DstTySize) const451 ConstantRange ConstantRange::signExtend(uint32_t DstTySize) const {
452   if (isEmptySet()) return ConstantRange(DstTySize, /*isFullSet=*/false);
453 
454   unsigned SrcTySize = getBitWidth();
455   assert(SrcTySize < DstTySize && "Not a value extension");
456   if (isFullSet() || isSignWrappedSet()) {
457     return ConstantRange(APInt::getHighBitsSet(DstTySize,DstTySize-SrcTySize+1),
458                          APInt::getLowBitsSet(DstTySize, SrcTySize-1) + 1);
459   }
460 
461   return ConstantRange(Lower.sext(DstTySize), Upper.sext(DstTySize));
462 }
463 
464 /// truncate - Return a new range in the specified integer type, which must be
465 /// strictly smaller than the current type.  The returned range will
466 /// correspond to the possible range of values as if the source range had been
467 /// truncated to the specified type.
truncate(uint32_t DstTySize) const468 ConstantRange ConstantRange::truncate(uint32_t DstTySize) const {
469   unsigned SrcTySize = getBitWidth();
470   assert(SrcTySize > DstTySize && "Not a value truncation");
471   APInt Size(APInt::getLowBitsSet(SrcTySize, DstTySize));
472   if (isFullSet() || getSetSize().ugt(Size))
473     return ConstantRange(DstTySize, /*isFullSet=*/true);
474 
475   return ConstantRange(Lower.trunc(DstTySize), Upper.trunc(DstTySize));
476 }
477 
478 /// zextOrTrunc - make this range have the bit width given by \p DstTySize. The
479 /// value is zero extended, truncated, or left alone to make it that width.
zextOrTrunc(uint32_t DstTySize) const480 ConstantRange ConstantRange::zextOrTrunc(uint32_t DstTySize) const {
481   unsigned SrcTySize = getBitWidth();
482   if (SrcTySize > DstTySize)
483     return truncate(DstTySize);
484   else if (SrcTySize < DstTySize)
485     return zeroExtend(DstTySize);
486   else
487     return *this;
488 }
489 
490 /// sextOrTrunc - make this range have the bit width given by \p DstTySize. The
491 /// value is sign extended, truncated, or left alone to make it that width.
sextOrTrunc(uint32_t DstTySize) const492 ConstantRange ConstantRange::sextOrTrunc(uint32_t DstTySize) const {
493   unsigned SrcTySize = getBitWidth();
494   if (SrcTySize > DstTySize)
495     return truncate(DstTySize);
496   else if (SrcTySize < DstTySize)
497     return signExtend(DstTySize);
498   else
499     return *this;
500 }
501 
502 ConstantRange
add(const ConstantRange & Other) const503 ConstantRange::add(const ConstantRange &Other) const {
504   if (isEmptySet() || Other.isEmptySet())
505     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
506   if (isFullSet() || Other.isFullSet())
507     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
508 
509   APInt Spread_X = getSetSize(), Spread_Y = Other.getSetSize();
510   APInt NewLower = getLower() + Other.getLower();
511   APInt NewUpper = getUpper() + Other.getUpper() - 1;
512   if (NewLower == NewUpper)
513     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
514 
515   ConstantRange X = ConstantRange(NewLower, NewUpper);
516   if (X.getSetSize().ult(Spread_X) || X.getSetSize().ult(Spread_Y))
517     // We've wrapped, therefore, full set.
518     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
519 
520   return X;
521 }
522 
523 ConstantRange
sub(const ConstantRange & Other) const524 ConstantRange::sub(const ConstantRange &Other) const {
525   if (isEmptySet() || Other.isEmptySet())
526     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
527   if (isFullSet() || Other.isFullSet())
528     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
529 
530   APInt Spread_X = getSetSize(), Spread_Y = Other.getSetSize();
531   APInt NewLower = getLower() - Other.getUpper() + 1;
532   APInt NewUpper = getUpper() - Other.getLower();
533   if (NewLower == NewUpper)
534     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
535 
536   ConstantRange X = ConstantRange(NewLower, NewUpper);
537   if (X.getSetSize().ult(Spread_X) || X.getSetSize().ult(Spread_Y))
538     // We've wrapped, therefore, full set.
539     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
540 
541   return X;
542 }
543 
544 ConstantRange
multiply(const ConstantRange & Other) const545 ConstantRange::multiply(const ConstantRange &Other) const {
546   // TODO: If either operand is a single element and the multiply is known to
547   // be non-wrapping, round the result min and max value to the appropriate
548   // multiple of that element. If wrapping is possible, at least adjust the
549   // range according to the greatest power-of-two factor of the single element.
550 
551   if (isEmptySet() || Other.isEmptySet())
552     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
553   if (isFullSet() || Other.isFullSet())
554     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
555 
556   APInt this_min = getUnsignedMin().zext(getBitWidth() * 2);
557   APInt this_max = getUnsignedMax().zext(getBitWidth() * 2);
558   APInt Other_min = Other.getUnsignedMin().zext(getBitWidth() * 2);
559   APInt Other_max = Other.getUnsignedMax().zext(getBitWidth() * 2);
560 
561   ConstantRange Result_zext = ConstantRange(this_min * Other_min,
562                                             this_max * Other_max + 1);
563   return Result_zext.truncate(getBitWidth());
564 }
565 
566 ConstantRange
smax(const ConstantRange & Other) const567 ConstantRange::smax(const ConstantRange &Other) const {
568   // X smax Y is: range(smax(X_smin, Y_smin),
569   //                    smax(X_smax, Y_smax))
570   if (isEmptySet() || Other.isEmptySet())
571     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
572   APInt NewL = APIntOps::smax(getSignedMin(), Other.getSignedMin());
573   APInt NewU = APIntOps::smax(getSignedMax(), Other.getSignedMax()) + 1;
574   if (NewU == NewL)
575     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
576   return ConstantRange(NewL, NewU);
577 }
578 
579 ConstantRange
umax(const ConstantRange & Other) const580 ConstantRange::umax(const ConstantRange &Other) const {
581   // X umax Y is: range(umax(X_umin, Y_umin),
582   //                    umax(X_umax, Y_umax))
583   if (isEmptySet() || Other.isEmptySet())
584     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
585   APInt NewL = APIntOps::umax(getUnsignedMin(), Other.getUnsignedMin());
586   APInt NewU = APIntOps::umax(getUnsignedMax(), Other.getUnsignedMax()) + 1;
587   if (NewU == NewL)
588     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
589   return ConstantRange(NewL, NewU);
590 }
591 
592 ConstantRange
udiv(const ConstantRange & RHS) const593 ConstantRange::udiv(const ConstantRange &RHS) const {
594   if (isEmptySet() || RHS.isEmptySet() || RHS.getUnsignedMax() == 0)
595     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
596   if (RHS.isFullSet())
597     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
598 
599   APInt Lower = getUnsignedMin().udiv(RHS.getUnsignedMax());
600 
601   APInt RHS_umin = RHS.getUnsignedMin();
602   if (RHS_umin == 0) {
603     // We want the lowest value in RHS excluding zero. Usually that would be 1
604     // except for a range in the form of [X, 1) in which case it would be X.
605     if (RHS.getUpper() == 1)
606       RHS_umin = RHS.getLower();
607     else
608       RHS_umin = APInt(getBitWidth(), 1);
609   }
610 
611   APInt Upper = getUnsignedMax().udiv(RHS_umin) + 1;
612 
613   // If the LHS is Full and the RHS is a wrapped interval containing 1 then
614   // this could occur.
615   if (Lower == Upper)
616     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
617 
618   return ConstantRange(Lower, Upper);
619 }
620 
621 ConstantRange
binaryAnd(const ConstantRange & Other) const622 ConstantRange::binaryAnd(const ConstantRange &Other) const {
623   if (isEmptySet() || Other.isEmptySet())
624     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
625 
626   // TODO: replace this with something less conservative
627 
628   APInt umin = APIntOps::umin(Other.getUnsignedMax(), getUnsignedMax());
629   if (umin.isAllOnesValue())
630     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
631   return ConstantRange(APInt::getNullValue(getBitWidth()), umin + 1);
632 }
633 
634 ConstantRange
binaryOr(const ConstantRange & Other) const635 ConstantRange::binaryOr(const ConstantRange &Other) const {
636   if (isEmptySet() || Other.isEmptySet())
637     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
638 
639   // TODO: replace this with something less conservative
640 
641   APInt umax = APIntOps::umax(getUnsignedMin(), Other.getUnsignedMin());
642   if (umax.isMinValue())
643     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
644   return ConstantRange(umax, APInt::getNullValue(getBitWidth()));
645 }
646 
647 ConstantRange
shl(const ConstantRange & Other) const648 ConstantRange::shl(const ConstantRange &Other) const {
649   if (isEmptySet() || Other.isEmptySet())
650     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
651 
652   APInt min = getUnsignedMin().shl(Other.getUnsignedMin());
653   APInt max = getUnsignedMax().shl(Other.getUnsignedMax());
654 
655   // there's no overflow!
656   APInt Zeros(getBitWidth(), getUnsignedMax().countLeadingZeros());
657   if (Zeros.ugt(Other.getUnsignedMax()))
658     return ConstantRange(min, max + 1);
659 
660   // FIXME: implement the other tricky cases
661   return ConstantRange(getBitWidth(), /*isFullSet=*/true);
662 }
663 
664 ConstantRange
lshr(const ConstantRange & Other) const665 ConstantRange::lshr(const ConstantRange &Other) const {
666   if (isEmptySet() || Other.isEmptySet())
667     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
668 
669   APInt max = getUnsignedMax().lshr(Other.getUnsignedMin());
670   APInt min = getUnsignedMin().lshr(Other.getUnsignedMax());
671   if (min == max + 1)
672     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
673 
674   return ConstantRange(min, max + 1);
675 }
676 
inverse() const677 ConstantRange ConstantRange::inverse() const {
678   if (isFullSet()) {
679     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
680   } else if (isEmptySet()) {
681     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
682   }
683   return ConstantRange(Upper, Lower);
684 }
685 
686 /// print - Print out the bounds to a stream...
687 ///
print(raw_ostream & OS) const688 void ConstantRange::print(raw_ostream &OS) const {
689   if (isFullSet())
690     OS << "full-set";
691   else if (isEmptySet())
692     OS << "empty-set";
693   else
694     OS << "[" << Lower << "," << Upper << ")";
695 }
696 
697 /// dump - Allow printing from a debugger easily...
698 ///
dump() const699 void ConstantRange::dump() const {
700   print(dbgs());
701 }
702