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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/IR/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: llvm_unreachable("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()+1, 0);
148 
149   if (isFullSet()) {
150     APInt Size(getBitWidth()+1, 0);
151     Size.setBit(getBitWidth());
152     return Size;
153   }
154 
155   // This is also correct for wrapped sets.
156   return (Upper - Lower).zext(getBitWidth()+1);
157 }
158 
159 /// getUnsignedMax - Return the largest unsigned value contained in the
160 /// ConstantRange.
161 ///
getUnsignedMax() const162 APInt ConstantRange::getUnsignedMax() const {
163   if (isFullSet() || isWrappedSet())
164     return APInt::getMaxValue(getBitWidth());
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   return getLower();
175 }
176 
177 /// getSignedMax - Return the largest signed value contained in the
178 /// ConstantRange.
179 ///
getSignedMax() const180 APInt ConstantRange::getSignedMax() const {
181   APInt SignedMax(APInt::getSignedMaxValue(getBitWidth()));
182   if (!isWrappedSet()) {
183     if (getLower().sle(getUpper() - 1))
184       return getUpper() - 1;
185     return SignedMax;
186   }
187   if (getLower().isNegative() == getUpper().isNegative())
188     return SignedMax;
189   return getUpper() - 1;
190 }
191 
192 /// getSignedMin - Return the smallest signed value contained in the
193 /// ConstantRange.
194 ///
getSignedMin() const195 APInt ConstantRange::getSignedMin() const {
196   APInt SignedMin(APInt::getSignedMinValue(getBitWidth()));
197   if (!isWrappedSet()) {
198     if (getLower().sle(getUpper() - 1))
199       return getLower();
200     return SignedMin;
201   }
202   if ((getUpper() - 1).slt(getLower())) {
203     if (getUpper() != SignedMin)
204       return SignedMin;
205   }
206   return getLower();
207 }
208 
209 /// contains - Return true if the specified value is in the set.
210 ///
contains(const APInt & V) const211 bool ConstantRange::contains(const APInt &V) const {
212   if (Lower == Upper)
213     return isFullSet();
214 
215   if (!isWrappedSet())
216     return Lower.ule(V) && V.ult(Upper);
217   return Lower.ule(V) || V.ult(Upper);
218 }
219 
220 /// contains - Return true if the argument is a subset of this range.
221 /// Two equal sets contain each other. The empty set contained by all other
222 /// sets.
223 ///
contains(const ConstantRange & Other) const224 bool ConstantRange::contains(const ConstantRange &Other) const {
225   if (isFullSet() || Other.isEmptySet()) return true;
226   if (isEmptySet() || Other.isFullSet()) return false;
227 
228   if (!isWrappedSet()) {
229     if (Other.isWrappedSet())
230       return false;
231 
232     return Lower.ule(Other.getLower()) && Other.getUpper().ule(Upper);
233   }
234 
235   if (!Other.isWrappedSet())
236     return Other.getUpper().ule(Upper) ||
237            Lower.ule(Other.getLower());
238 
239   return Other.getUpper().ule(Upper) && Lower.ule(Other.getLower());
240 }
241 
242 /// subtract - Subtract the specified constant from the endpoints of this
243 /// constant range.
subtract(const APInt & Val) const244 ConstantRange ConstantRange::subtract(const APInt &Val) const {
245   assert(Val.getBitWidth() == getBitWidth() && "Wrong bit width");
246   // If the set is empty or full, don't modify the endpoints.
247   if (Lower == Upper)
248     return *this;
249   return ConstantRange(Lower - Val, Upper - Val);
250 }
251 
252 /// \brief Subtract the specified range from this range (aka relative complement
253 /// of the sets).
difference(const ConstantRange & CR) const254 ConstantRange ConstantRange::difference(const ConstantRange &CR) const {
255   return intersectWith(CR.inverse());
256 }
257 
258 /// intersectWith - Return the range that results from the intersection of this
259 /// range with another range.  The resultant range is guaranteed to include all
260 /// elements contained in both input ranges, and to have the smallest possible
261 /// set size that does so.  Because there may be two intersections with the
262 /// same set size, A.intersectWith(B) might not be equal to B.intersectWith(A).
intersectWith(const ConstantRange & CR) const263 ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const {
264   assert(getBitWidth() == CR.getBitWidth() &&
265          "ConstantRange types don't agree!");
266 
267   // Handle common cases.
268   if (   isEmptySet() || CR.isFullSet()) return *this;
269   if (CR.isEmptySet() ||    isFullSet()) return CR;
270 
271   if (!isWrappedSet() && CR.isWrappedSet())
272     return CR.intersectWith(*this);
273 
274   if (!isWrappedSet() && !CR.isWrappedSet()) {
275     if (Lower.ult(CR.Lower)) {
276       if (Upper.ule(CR.Lower))
277         return ConstantRange(getBitWidth(), false);
278 
279       if (Upper.ult(CR.Upper))
280         return ConstantRange(CR.Lower, Upper);
281 
282       return CR;
283     }
284     if (Upper.ult(CR.Upper))
285       return *this;
286 
287     if (Lower.ult(CR.Upper))
288       return ConstantRange(Lower, CR.Upper);
289 
290     return ConstantRange(getBitWidth(), false);
291   }
292 
293   if (isWrappedSet() && !CR.isWrappedSet()) {
294     if (CR.Lower.ult(Upper)) {
295       if (CR.Upper.ult(Upper))
296         return CR;
297 
298       if (CR.Upper.ule(Lower))
299         return ConstantRange(CR.Lower, Upper);
300 
301       if (getSetSize().ult(CR.getSetSize()))
302         return *this;
303       return CR;
304     }
305     if (CR.Lower.ult(Lower)) {
306       if (CR.Upper.ule(Lower))
307         return ConstantRange(getBitWidth(), false);
308 
309       return ConstantRange(Lower, CR.Upper);
310     }
311     return CR;
312   }
313 
314   if (CR.Upper.ult(Upper)) {
315     if (CR.Lower.ult(Upper)) {
316       if (getSetSize().ult(CR.getSetSize()))
317         return *this;
318       return CR;
319     }
320 
321     if (CR.Lower.ult(Lower))
322       return ConstantRange(Lower, CR.Upper);
323 
324     return CR;
325   }
326   if (CR.Upper.ule(Lower)) {
327     if (CR.Lower.ult(Lower))
328       return *this;
329 
330     return ConstantRange(CR.Lower, Upper);
331   }
332   if (getSetSize().ult(CR.getSetSize()))
333     return *this;
334   return CR;
335 }
336 
337 
338 /// unionWith - Return the range that results from the union of this range with
339 /// another range.  The resultant range is guaranteed to include the elements of
340 /// both sets, but may contain more.  For example, [3, 9) union [12,15) is
341 /// [3, 15), which includes 9, 10, and 11, which were not included in either
342 /// set before.
343 ///
unionWith(const ConstantRange & CR) const344 ConstantRange ConstantRange::unionWith(const ConstantRange &CR) const {
345   assert(getBitWidth() == CR.getBitWidth() &&
346          "ConstantRange types don't agree!");
347 
348   if (   isFullSet() || CR.isEmptySet()) return *this;
349   if (CR.isFullSet() ||    isEmptySet()) return CR;
350 
351   if (!isWrappedSet() && CR.isWrappedSet()) return CR.unionWith(*this);
352 
353   if (!isWrappedSet() && !CR.isWrappedSet()) {
354     if (CR.Upper.ult(Lower) || Upper.ult(CR.Lower)) {
355       // If the two ranges are disjoint, find the smaller gap and bridge it.
356       APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Upper;
357       if (d1.ult(d2))
358         return ConstantRange(Lower, CR.Upper);
359       return ConstantRange(CR.Lower, Upper);
360     }
361 
362     APInt L = Lower, U = Upper;
363     if (CR.Lower.ult(L))
364       L = CR.Lower;
365     if ((CR.Upper - 1).ugt(U - 1))
366       U = CR.Upper;
367 
368     if (L == 0 && U == 0)
369       return ConstantRange(getBitWidth());
370 
371     return ConstantRange(L, U);
372   }
373 
374   if (!CR.isWrappedSet()) {
375     // ------U   L-----  and  ------U   L----- : this
376     //   L--U                            L--U  : CR
377     if (CR.Upper.ule(Upper) || CR.Lower.uge(Lower))
378       return *this;
379 
380     // ------U   L----- : this
381     //    L---------U   : CR
382     if (CR.Lower.ule(Upper) && Lower.ule(CR.Upper))
383       return ConstantRange(getBitWidth());
384 
385     // ----U       L---- : this
386     //       L---U       : CR
387     //    <d1>  <d2>
388     if (Upper.ule(CR.Lower) && CR.Upper.ule(Lower)) {
389       APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Upper;
390       if (d1.ult(d2))
391         return ConstantRange(Lower, CR.Upper);
392       return ConstantRange(CR.Lower, Upper);
393     }
394 
395     // ----U     L----- : this
396     //        L----U    : CR
397     if (Upper.ult(CR.Lower) && Lower.ult(CR.Upper))
398       return ConstantRange(CR.Lower, Upper);
399 
400     // ------U    L---- : this
401     //    L-----U       : CR
402     assert(CR.Lower.ult(Upper) && CR.Upper.ult(Lower) &&
403            "ConstantRange::unionWith missed a case with one range wrapped");
404     return ConstantRange(Lower, CR.Upper);
405   }
406 
407   // ------U    L----  and  ------U    L---- : this
408   // -U  L-----------  and  ------------U  L : CR
409   if (CR.Lower.ule(Upper) || Lower.ule(CR.Upper))
410     return ConstantRange(getBitWidth());
411 
412   APInt L = Lower, U = Upper;
413   if (CR.Upper.ugt(U))
414     U = CR.Upper;
415   if (CR.Lower.ult(L))
416     L = CR.Lower;
417 
418   return ConstantRange(L, U);
419 }
420 
421 /// zeroExtend - Return a new range in the specified integer type, which must
422 /// be strictly larger than the current type.  The returned range will
423 /// correspond to the possible range of values as if the source range had been
424 /// zero extended.
zeroExtend(uint32_t DstTySize) const425 ConstantRange ConstantRange::zeroExtend(uint32_t DstTySize) const {
426   if (isEmptySet()) return ConstantRange(DstTySize, /*isFullSet=*/false);
427 
428   unsigned SrcTySize = getBitWidth();
429   assert(SrcTySize < DstTySize && "Not a value extension");
430   if (isFullSet() || isWrappedSet()) {
431     // Change into [0, 1 << src bit width)
432     APInt LowerExt(DstTySize, 0);
433     if (!Upper) // special case: [X, 0) -- not really wrapping around
434       LowerExt = Lower.zext(DstTySize);
435     return ConstantRange(LowerExt, APInt(DstTySize, 1).shl(SrcTySize));
436   }
437 
438   return ConstantRange(Lower.zext(DstTySize), Upper.zext(DstTySize));
439 }
440 
441 /// signExtend - Return a new range in the specified integer type, which must
442 /// be strictly larger than the current type.  The returned range will
443 /// correspond to the possible range of values as if the source range had been
444 /// sign extended.
signExtend(uint32_t DstTySize) const445 ConstantRange ConstantRange::signExtend(uint32_t DstTySize) const {
446   if (isEmptySet()) return ConstantRange(DstTySize, /*isFullSet=*/false);
447 
448   unsigned SrcTySize = getBitWidth();
449   assert(SrcTySize < DstTySize && "Not a value extension");
450   if (isFullSet() || isSignWrappedSet()) {
451     return ConstantRange(APInt::getHighBitsSet(DstTySize,DstTySize-SrcTySize+1),
452                          APInt::getLowBitsSet(DstTySize, SrcTySize-1) + 1);
453   }
454 
455   return ConstantRange(Lower.sext(DstTySize), Upper.sext(DstTySize));
456 }
457 
458 /// truncate - Return a new range in the specified integer type, which must be
459 /// strictly smaller than the current type.  The returned range will
460 /// correspond to the possible range of values as if the source range had been
461 /// truncated to the specified type.
truncate(uint32_t DstTySize) const462 ConstantRange ConstantRange::truncate(uint32_t DstTySize) const {
463   assert(getBitWidth() > DstTySize && "Not a value truncation");
464   if (isEmptySet())
465     return ConstantRange(DstTySize, /*isFullSet=*/false);
466   if (isFullSet())
467     return ConstantRange(DstTySize, /*isFullSet=*/true);
468 
469   APInt MaxValue = APInt::getMaxValue(DstTySize).zext(getBitWidth());
470   APInt MaxBitValue(getBitWidth(), 0);
471   MaxBitValue.setBit(DstTySize);
472 
473   APInt LowerDiv(Lower), UpperDiv(Upper);
474   ConstantRange Union(DstTySize, /*isFullSet=*/false);
475 
476   // Analyze wrapped sets in their two parts: [0, Upper) \/ [Lower, MaxValue]
477   // We use the non-wrapped set code to analyze the [Lower, MaxValue) part, and
478   // then we do the union with [MaxValue, Upper)
479   if (isWrappedSet()) {
480     // if Upper is greater than Max Value, it covers the whole truncated range.
481     if (Upper.uge(MaxValue))
482       return ConstantRange(DstTySize, /*isFullSet=*/true);
483 
484     Union = ConstantRange(APInt::getMaxValue(DstTySize),Upper.trunc(DstTySize));
485     UpperDiv = APInt::getMaxValue(getBitWidth());
486 
487     // Union covers the MaxValue case, so return if the remaining range is just
488     // MaxValue.
489     if (LowerDiv == UpperDiv)
490       return Union;
491   }
492 
493   // Chop off the most significant bits that are past the destination bitwidth.
494   if (LowerDiv.uge(MaxValue)) {
495     APInt Div(getBitWidth(), 0);
496     APInt::udivrem(LowerDiv, MaxBitValue, Div, LowerDiv);
497     UpperDiv = UpperDiv - MaxBitValue * Div;
498   }
499 
500   if (UpperDiv.ule(MaxValue))
501     return ConstantRange(LowerDiv.trunc(DstTySize),
502                          UpperDiv.trunc(DstTySize)).unionWith(Union);
503 
504   // The truncated value wrapps around. Check if we can do better than fullset.
505   APInt UpperModulo = UpperDiv - MaxBitValue;
506   if (UpperModulo.ult(LowerDiv))
507     return ConstantRange(LowerDiv.trunc(DstTySize),
508                          UpperModulo.trunc(DstTySize)).unionWith(Union);
509 
510   return ConstantRange(DstTySize, /*isFullSet=*/true);
511 }
512 
513 /// zextOrTrunc - make this range have the bit width given by \p DstTySize. The
514 /// value is zero extended, truncated, or left alone to make it that width.
zextOrTrunc(uint32_t DstTySize) const515 ConstantRange ConstantRange::zextOrTrunc(uint32_t DstTySize) const {
516   unsigned SrcTySize = getBitWidth();
517   if (SrcTySize > DstTySize)
518     return truncate(DstTySize);
519   if (SrcTySize < DstTySize)
520     return zeroExtend(DstTySize);
521   return *this;
522 }
523 
524 /// sextOrTrunc - make this range have the bit width given by \p DstTySize. The
525 /// value is sign extended, truncated, or left alone to make it that width.
sextOrTrunc(uint32_t DstTySize) const526 ConstantRange ConstantRange::sextOrTrunc(uint32_t DstTySize) const {
527   unsigned SrcTySize = getBitWidth();
528   if (SrcTySize > DstTySize)
529     return truncate(DstTySize);
530   if (SrcTySize < DstTySize)
531     return signExtend(DstTySize);
532   return *this;
533 }
534 
535 ConstantRange
add(const ConstantRange & Other) const536 ConstantRange::add(const ConstantRange &Other) const {
537   if (isEmptySet() || Other.isEmptySet())
538     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
539   if (isFullSet() || Other.isFullSet())
540     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
541 
542   APInt Spread_X = getSetSize(), Spread_Y = Other.getSetSize();
543   APInt NewLower = getLower() + Other.getLower();
544   APInt NewUpper = getUpper() + Other.getUpper() - 1;
545   if (NewLower == NewUpper)
546     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
547 
548   ConstantRange X = ConstantRange(NewLower, NewUpper);
549   if (X.getSetSize().ult(Spread_X) || X.getSetSize().ult(Spread_Y))
550     // We've wrapped, therefore, full set.
551     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
552 
553   return X;
554 }
555 
556 ConstantRange
sub(const ConstantRange & Other) const557 ConstantRange::sub(const ConstantRange &Other) const {
558   if (isEmptySet() || Other.isEmptySet())
559     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
560   if (isFullSet() || Other.isFullSet())
561     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
562 
563   APInt Spread_X = getSetSize(), Spread_Y = Other.getSetSize();
564   APInt NewLower = getLower() - Other.getUpper() + 1;
565   APInt NewUpper = getUpper() - Other.getLower();
566   if (NewLower == NewUpper)
567     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
568 
569   ConstantRange X = ConstantRange(NewLower, NewUpper);
570   if (X.getSetSize().ult(Spread_X) || X.getSetSize().ult(Spread_Y))
571     // We've wrapped, therefore, full set.
572     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
573 
574   return X;
575 }
576 
577 ConstantRange
multiply(const ConstantRange & Other) const578 ConstantRange::multiply(const ConstantRange &Other) const {
579   // TODO: If either operand is a single element and the multiply is known to
580   // be non-wrapping, round the result min and max value to the appropriate
581   // multiple of that element. If wrapping is possible, at least adjust the
582   // range according to the greatest power-of-two factor of the single element.
583 
584   if (isEmptySet() || Other.isEmptySet())
585     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
586 
587   APInt this_min = getUnsignedMin().zext(getBitWidth() * 2);
588   APInt this_max = getUnsignedMax().zext(getBitWidth() * 2);
589   APInt Other_min = Other.getUnsignedMin().zext(getBitWidth() * 2);
590   APInt Other_max = Other.getUnsignedMax().zext(getBitWidth() * 2);
591 
592   ConstantRange Result_zext = ConstantRange(this_min * Other_min,
593                                             this_max * Other_max + 1);
594   return Result_zext.truncate(getBitWidth());
595 }
596 
597 ConstantRange
smax(const ConstantRange & Other) const598 ConstantRange::smax(const ConstantRange &Other) const {
599   // X smax Y is: range(smax(X_smin, Y_smin),
600   //                    smax(X_smax, Y_smax))
601   if (isEmptySet() || Other.isEmptySet())
602     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
603   APInt NewL = APIntOps::smax(getSignedMin(), Other.getSignedMin());
604   APInt NewU = APIntOps::smax(getSignedMax(), Other.getSignedMax()) + 1;
605   if (NewU == NewL)
606     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
607   return ConstantRange(NewL, NewU);
608 }
609 
610 ConstantRange
umax(const ConstantRange & Other) const611 ConstantRange::umax(const ConstantRange &Other) const {
612   // X umax Y is: range(umax(X_umin, Y_umin),
613   //                    umax(X_umax, Y_umax))
614   if (isEmptySet() || Other.isEmptySet())
615     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
616   APInt NewL = APIntOps::umax(getUnsignedMin(), Other.getUnsignedMin());
617   APInt NewU = APIntOps::umax(getUnsignedMax(), Other.getUnsignedMax()) + 1;
618   if (NewU == NewL)
619     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
620   return ConstantRange(NewL, NewU);
621 }
622 
623 ConstantRange
udiv(const ConstantRange & RHS) const624 ConstantRange::udiv(const ConstantRange &RHS) const {
625   if (isEmptySet() || RHS.isEmptySet() || RHS.getUnsignedMax() == 0)
626     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
627   if (RHS.isFullSet())
628     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
629 
630   APInt Lower = getUnsignedMin().udiv(RHS.getUnsignedMax());
631 
632   APInt RHS_umin = RHS.getUnsignedMin();
633   if (RHS_umin == 0) {
634     // We want the lowest value in RHS excluding zero. Usually that would be 1
635     // except for a range in the form of [X, 1) in which case it would be X.
636     if (RHS.getUpper() == 1)
637       RHS_umin = RHS.getLower();
638     else
639       RHS_umin = APInt(getBitWidth(), 1);
640   }
641 
642   APInt Upper = getUnsignedMax().udiv(RHS_umin) + 1;
643 
644   // If the LHS is Full and the RHS is a wrapped interval containing 1 then
645   // this could occur.
646   if (Lower == Upper)
647     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
648 
649   return ConstantRange(Lower, Upper);
650 }
651 
652 ConstantRange
binaryAnd(const ConstantRange & Other) const653 ConstantRange::binaryAnd(const ConstantRange &Other) const {
654   if (isEmptySet() || Other.isEmptySet())
655     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
656 
657   // TODO: replace this with something less conservative
658 
659   APInt umin = APIntOps::umin(Other.getUnsignedMax(), getUnsignedMax());
660   if (umin.isAllOnesValue())
661     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
662   return ConstantRange(APInt::getNullValue(getBitWidth()), umin + 1);
663 }
664 
665 ConstantRange
binaryOr(const ConstantRange & Other) const666 ConstantRange::binaryOr(const ConstantRange &Other) const {
667   if (isEmptySet() || Other.isEmptySet())
668     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
669 
670   // TODO: replace this with something less conservative
671 
672   APInt umax = APIntOps::umax(getUnsignedMin(), Other.getUnsignedMin());
673   if (umax.isMinValue())
674     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
675   return ConstantRange(umax, APInt::getNullValue(getBitWidth()));
676 }
677 
678 ConstantRange
shl(const ConstantRange & Other) const679 ConstantRange::shl(const ConstantRange &Other) const {
680   if (isEmptySet() || Other.isEmptySet())
681     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
682 
683   APInt min = getUnsignedMin().shl(Other.getUnsignedMin());
684   APInt max = getUnsignedMax().shl(Other.getUnsignedMax());
685 
686   // there's no overflow!
687   APInt Zeros(getBitWidth(), getUnsignedMax().countLeadingZeros());
688   if (Zeros.ugt(Other.getUnsignedMax()))
689     return ConstantRange(min, max + 1);
690 
691   // FIXME: implement the other tricky cases
692   return ConstantRange(getBitWidth(), /*isFullSet=*/true);
693 }
694 
695 ConstantRange
lshr(const ConstantRange & Other) const696 ConstantRange::lshr(const ConstantRange &Other) const {
697   if (isEmptySet() || Other.isEmptySet())
698     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
699 
700   APInt max = getUnsignedMax().lshr(Other.getUnsignedMin());
701   APInt min = getUnsignedMin().lshr(Other.getUnsignedMax());
702   if (min == max + 1)
703     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
704 
705   return ConstantRange(min, max + 1);
706 }
707 
inverse() const708 ConstantRange ConstantRange::inverse() const {
709   if (isFullSet())
710     return ConstantRange(getBitWidth(), /*isFullSet=*/false);
711   if (isEmptySet())
712     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
713   return ConstantRange(Upper, Lower);
714 }
715 
716 /// print - Print out the bounds to a stream...
717 ///
print(raw_ostream & OS) const718 void ConstantRange::print(raw_ostream &OS) const {
719   if (isFullSet())
720     OS << "full-set";
721   else if (isEmptySet())
722     OS << "empty-set";
723   else
724     OS << "[" << Lower << "," << Upper << ")";
725 }
726 
727 /// dump - Allow printing from a debugger easily...
728 ///
dump() const729 void ConstantRange::dump() const {
730   print(dbgs());
731 }
732