clang  5.0.0svn
RangeConstraintManager.cpp
Go to the documentation of this file.
1 //== RangeConstraintManager.cpp - Manage range constraints.------*- C++ -*--==//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines RangeConstraintManager, a class that tracks simple
11 // equality and inequality constraints on symbolic values of ProgramState.
12 //
13 //===----------------------------------------------------------------------===//
14 
19 #include "llvm/ADT/FoldingSet.h"
20 #include "llvm/ADT/ImmutableSet.h"
21 #include "llvm/Support/raw_ostream.h"
22 
23 using namespace clang;
24 using namespace ento;
25 
26 /// A Range represents the closed range [from, to]. The caller must
27 /// guarantee that from <= to. Note that Range is immutable, so as not
28 /// to subvert RangeSet's immutability.
29 namespace {
30 class Range : public std::pair<const llvm::APSInt *, const llvm::APSInt *> {
31 public:
32  Range(const llvm::APSInt &from, const llvm::APSInt &to)
33  : std::pair<const llvm::APSInt *, const llvm::APSInt *>(&from, &to) {
34  assert(from <= to);
35  }
36  bool Includes(const llvm::APSInt &v) const {
37  return *first <= v && v <= *second;
38  }
39  const llvm::APSInt &From() const { return *first; }
40  const llvm::APSInt &To() const { return *second; }
41  const llvm::APSInt *getConcreteValue() const {
42  return &From() == &To() ? &From() : nullptr;
43  }
44 
45  void Profile(llvm::FoldingSetNodeID &ID) const {
46  ID.AddPointer(&From());
47  ID.AddPointer(&To());
48  }
49 };
50 
51 class RangeTrait : public llvm::ImutContainerInfo<Range> {
52 public:
53  // When comparing if one Range is less than another, we should compare
54  // the actual APSInt values instead of their pointers. This keeps the order
55  // consistent (instead of comparing by pointer values) and can potentially
56  // be used to speed up some of the operations in RangeSet.
57  static inline bool isLess(key_type_ref lhs, key_type_ref rhs) {
58  return *lhs.first < *rhs.first ||
59  (!(*rhs.first < *lhs.first) && *lhs.second < *rhs.second);
60  }
61 };
62 
63 /// RangeSet contains a set of ranges. If the set is empty, then
64 /// there the value of a symbol is overly constrained and there are no
65 /// possible values for that symbol.
66 class RangeSet {
67  typedef llvm::ImmutableSet<Range, RangeTrait> PrimRangeSet;
68  PrimRangeSet ranges; // no need to make const, since it is an
69  // ImmutableSet - this allows default operator=
70  // to work.
71 public:
72  typedef PrimRangeSet::Factory Factory;
73  typedef PrimRangeSet::iterator iterator;
74 
75  RangeSet(PrimRangeSet RS) : ranges(RS) {}
76 
77  /// Create a new set with all ranges of this set and RS.
78  /// Possible intersections are not checked here.
79  RangeSet addRange(Factory &F, const RangeSet &RS) {
80  PrimRangeSet Ranges(RS.ranges);
81  for (const auto &range : ranges)
82  Ranges = F.add(Ranges, range);
83  return RangeSet(Ranges);
84  }
85 
86  iterator begin() const { return ranges.begin(); }
87  iterator end() const { return ranges.end(); }
88 
89  bool isEmpty() const { return ranges.isEmpty(); }
90 
91  /// Construct a new RangeSet representing '{ [from, to] }'.
92  RangeSet(Factory &F, const llvm::APSInt &from, const llvm::APSInt &to)
93  : ranges(F.add(F.getEmptySet(), Range(from, to))) {}
94 
95  /// Profile - Generates a hash profile of this RangeSet for use
96  /// by FoldingSet.
97  void Profile(llvm::FoldingSetNodeID &ID) const { ranges.Profile(ID); }
98 
99  /// getConcreteValue - If a symbol is contrained to equal a specific integer
100  /// constant then this method returns that value. Otherwise, it returns
101  /// NULL.
102  const llvm::APSInt *getConcreteValue() const {
103  return ranges.isSingleton() ? ranges.begin()->getConcreteValue() : nullptr;
104  }
105 
106 private:
107  void IntersectInRange(BasicValueFactory &BV, Factory &F,
108  const llvm::APSInt &Lower, const llvm::APSInt &Upper,
109  PrimRangeSet &newRanges, PrimRangeSet::iterator &i,
110  PrimRangeSet::iterator &e) const {
111  // There are six cases for each range R in the set:
112  // 1. R is entirely before the intersection range.
113  // 2. R is entirely after the intersection range.
114  // 3. R contains the entire intersection range.
115  // 4. R starts before the intersection range and ends in the middle.
116  // 5. R starts in the middle of the intersection range and ends after it.
117  // 6. R is entirely contained in the intersection range.
118  // These correspond to each of the conditions below.
119  for (/* i = begin(), e = end() */; i != e; ++i) {
120  if (i->To() < Lower) {
121  continue;
122  }
123  if (i->From() > Upper) {
124  break;
125  }
126 
127  if (i->Includes(Lower)) {
128  if (i->Includes(Upper)) {
129  newRanges =
130  F.add(newRanges, Range(BV.getValue(Lower), BV.getValue(Upper)));
131  break;
132  } else
133  newRanges = F.add(newRanges, Range(BV.getValue(Lower), i->To()));
134  } else {
135  if (i->Includes(Upper)) {
136  newRanges = F.add(newRanges, Range(i->From(), BV.getValue(Upper)));
137  break;
138  } else
139  newRanges = F.add(newRanges, *i);
140  }
141  }
142  }
143 
144  const llvm::APSInt &getMinValue() const {
145  assert(!isEmpty());
146  return ranges.begin()->From();
147  }
148 
149  bool pin(llvm::APSInt &Lower, llvm::APSInt &Upper) const {
150  // This function has nine cases, the cartesian product of range-testing
151  // both the upper and lower bounds against the symbol's type.
152  // Each case requires a different pinning operation.
153  // The function returns false if the described range is entirely outside
154  // the range of values for the associated symbol.
155  APSIntType Type(getMinValue());
156  APSIntType::RangeTestResultKind LowerTest = Type.testInRange(Lower, true);
157  APSIntType::RangeTestResultKind UpperTest = Type.testInRange(Upper, true);
158 
159  switch (LowerTest) {
161  switch (UpperTest) {
163  // The entire range is outside the symbol's set of possible values.
164  // If this is a conventionally-ordered range, the state is infeasible.
165  if (Lower <= Upper)
166  return false;
167 
168  // However, if the range wraps around, it spans all possible values.
169  Lower = Type.getMinValue();
170  Upper = Type.getMaxValue();
171  break;
173  // The range starts below what's possible but ends within it. Pin.
174  Lower = Type.getMinValue();
175  Type.apply(Upper);
176  break;
178  // The range spans all possible values for the symbol. Pin.
179  Lower = Type.getMinValue();
180  Upper = Type.getMaxValue();
181  break;
182  }
183  break;
185  switch (UpperTest) {
187  // The range wraps around, but all lower values are not possible.
188  Type.apply(Lower);
189  Upper = Type.getMaxValue();
190  break;
192  // The range may or may not wrap around, but both limits are valid.
193  Type.apply(Lower);
194  Type.apply(Upper);
195  break;
197  // The range starts within what's possible but ends above it. Pin.
198  Type.apply(Lower);
199  Upper = Type.getMaxValue();
200  break;
201  }
202  break;
204  switch (UpperTest) {
206  // The range wraps but is outside the symbol's set of possible values.
207  return false;
209  // The range starts above what's possible but ends within it (wrap).
210  Lower = Type.getMinValue();
211  Type.apply(Upper);
212  break;
214  // The entire range is outside the symbol's set of possible values.
215  // If this is a conventionally-ordered range, the state is infeasible.
216  if (Lower <= Upper)
217  return false;
218 
219  // However, if the range wraps around, it spans all possible values.
220  Lower = Type.getMinValue();
221  Upper = Type.getMaxValue();
222  break;
223  }
224  break;
225  }
226 
227  return true;
228  }
229 
230 public:
231  // Returns a set containing the values in the receiving set, intersected with
232  // the closed range [Lower, Upper]. Unlike the Range type, this range uses
233  // modular arithmetic, corresponding to the common treatment of C integer
234  // overflow. Thus, if the Lower bound is greater than the Upper bound, the
235  // range is taken to wrap around. This is equivalent to taking the
236  // intersection with the two ranges [Min, Upper] and [Lower, Max],
237  // or, alternatively, /removing/ all integers between Upper and Lower.
238  RangeSet Intersect(BasicValueFactory &BV, Factory &F, llvm::APSInt Lower,
239  llvm::APSInt Upper) const {
240  if (!pin(Lower, Upper))
241  return F.getEmptySet();
242 
243  PrimRangeSet newRanges = F.getEmptySet();
244 
245  PrimRangeSet::iterator i = begin(), e = end();
246  if (Lower <= Upper)
247  IntersectInRange(BV, F, Lower, Upper, newRanges, i, e);
248  else {
249  // The order of the next two statements is important!
250  // IntersectInRange() does not reset the iteration state for i and e.
251  // Therefore, the lower range most be handled first.
252  IntersectInRange(BV, F, BV.getMinValue(Upper), Upper, newRanges, i, e);
253  IntersectInRange(BV, F, Lower, BV.getMaxValue(Lower), newRanges, i, e);
254  }
255 
256  return newRanges;
257  }
258 
259  void print(raw_ostream &os) const {
260  bool isFirst = true;
261  os << "{ ";
262  for (iterator i = begin(), e = end(); i != e; ++i) {
263  if (isFirst)
264  isFirst = false;
265  else
266  os << ", ";
267 
268  os << '[' << i->From().toString(10) << ", " << i->To().toString(10)
269  << ']';
270  }
271  os << " }";
272  }
273 
274  bool operator==(const RangeSet &other) const {
275  return ranges == other.ranges;
276  }
277 };
278 } // end anonymous namespace
279 
282  RangeSet))
283 
284 namespace {
285 class RangeConstraintManager : public RangedConstraintManager {
286 public:
287  RangeConstraintManager(SubEngine *SE, SValBuilder &SVB)
288  : RangedConstraintManager(SE, SVB) {}
289 
290  //===------------------------------------------------------------------===//
291  // Implementation for interface from ConstraintManager.
292  //===------------------------------------------------------------------===//
293 
294  bool canReasonAbout(SVal X) const override;
295 
296  ConditionTruthVal checkNull(ProgramStateRef State, SymbolRef Sym) override;
297 
298  const llvm::APSInt *getSymVal(ProgramStateRef State,
299  SymbolRef Sym) const override;
300 
301  ProgramStateRef removeDeadBindings(ProgramStateRef State,
302  SymbolReaper &SymReaper) override;
303 
304  void print(ProgramStateRef State, raw_ostream &Out, const char *nl,
305  const char *sep) override;
306 
307  //===------------------------------------------------------------------===//
308  // Implementation for interface from RangedConstraintManager.
309  //===------------------------------------------------------------------===//
310 
311  ProgramStateRef assumeSymNE(ProgramStateRef State, SymbolRef Sym,
312  const llvm::APSInt &V,
313  const llvm::APSInt &Adjustment) override;
314 
315  ProgramStateRef assumeSymEQ(ProgramStateRef State, SymbolRef Sym,
316  const llvm::APSInt &V,
317  const llvm::APSInt &Adjustment) override;
318 
319  ProgramStateRef assumeSymLT(ProgramStateRef State, SymbolRef Sym,
320  const llvm::APSInt &V,
321  const llvm::APSInt &Adjustment) override;
322 
323  ProgramStateRef assumeSymGT(ProgramStateRef State, SymbolRef Sym,
324  const llvm::APSInt &V,
325  const llvm::APSInt &Adjustment) override;
326 
327  ProgramStateRef assumeSymLE(ProgramStateRef State, SymbolRef Sym,
328  const llvm::APSInt &V,
329  const llvm::APSInt &Adjustment) override;
330 
331  ProgramStateRef assumeSymGE(ProgramStateRef State, SymbolRef Sym,
332  const llvm::APSInt &V,
333  const llvm::APSInt &Adjustment) override;
334 
335  ProgramStateRef assumeSymWithinInclusiveRange(
336  ProgramStateRef State, SymbolRef Sym, const llvm::APSInt &From,
337  const llvm::APSInt &To, const llvm::APSInt &Adjustment) override;
338 
339  ProgramStateRef assumeSymOutsideInclusiveRange(
340  ProgramStateRef State, SymbolRef Sym, const llvm::APSInt &From,
341  const llvm::APSInt &To, const llvm::APSInt &Adjustment) override;
342 
343 private:
344  RangeSet::Factory F;
345 
346  RangeSet getRange(ProgramStateRef State, SymbolRef Sym);
347 
348  RangeSet getSymLTRange(ProgramStateRef St, SymbolRef Sym,
349  const llvm::APSInt &Int,
350  const llvm::APSInt &Adjustment);
351  RangeSet getSymGTRange(ProgramStateRef St, SymbolRef Sym,
352  const llvm::APSInt &Int,
353  const llvm::APSInt &Adjustment);
354  RangeSet getSymLERange(ProgramStateRef St, SymbolRef Sym,
355  const llvm::APSInt &Int,
356  const llvm::APSInt &Adjustment);
357  RangeSet getSymLERange(const RangeSet &RS, const llvm::APSInt &Int,
358  const llvm::APSInt &Adjustment);
359  RangeSet getSymGERange(ProgramStateRef St, SymbolRef Sym,
360  const llvm::APSInt &Int,
361  const llvm::APSInt &Adjustment);
362 };
363 
364 } // end anonymous namespace
365 
366 std::unique_ptr<ConstraintManager>
368  return llvm::make_unique<RangeConstraintManager>(Eng, StMgr.getSValBuilder());
369 }
370 
371 bool RangeConstraintManager::canReasonAbout(SVal X) const {
373  if (SymVal && SymVal->isExpression()) {
374  const SymExpr *SE = SymVal->getSymbol();
375 
376  if (const SymIntExpr *SIE = dyn_cast<SymIntExpr>(SE)) {
377  switch (SIE->getOpcode()) {
378  // We don't reason yet about bitwise-constraints on symbolic values.
379  case BO_And:
380  case BO_Or:
381  case BO_Xor:
382  return false;
383  // We don't reason yet about these arithmetic constraints on
384  // symbolic values.
385  case BO_Mul:
386  case BO_Div:
387  case BO_Rem:
388  case BO_Shl:
389  case BO_Shr:
390  return false;
391  // All other cases.
392  default:
393  return true;
394  }
395  }
396 
397  if (const SymSymExpr *SSE = dyn_cast<SymSymExpr>(SE)) {
398  if (BinaryOperator::isComparisonOp(SSE->getOpcode())) {
399  // We handle Loc <> Loc comparisons, but not (yet) NonLoc <> NonLoc.
400  if (Loc::isLocType(SSE->getLHS()->getType())) {
401  assert(Loc::isLocType(SSE->getRHS()->getType()));
402  return true;
403  }
404  }
405  }
406 
407  return false;
408  }
409 
410  return true;
411 }
412 
413 ConditionTruthVal RangeConstraintManager::checkNull(ProgramStateRef State,
414  SymbolRef Sym) {
415  const RangeSet *Ranges = State->get<ConstraintRange>(Sym);
416 
417  // If we don't have any information about this symbol, it's underconstrained.
418  if (!Ranges)
419  return ConditionTruthVal();
420 
421  // If we have a concrete value, see if it's zero.
422  if (const llvm::APSInt *Value = Ranges->getConcreteValue())
423  return *Value == 0;
424 
425  BasicValueFactory &BV = getBasicVals();
426  APSIntType IntType = BV.getAPSIntType(Sym->getType());
427  llvm::APSInt Zero = IntType.getZeroValue();
428 
429  // Check if zero is in the set of possible values.
430  if (Ranges->Intersect(BV, F, Zero, Zero).isEmpty())
431  return false;
432 
433  // Zero is a possible value, but it is not the /only/ possible value.
434  return ConditionTruthVal();
435 }
436 
437 const llvm::APSInt *RangeConstraintManager::getSymVal(ProgramStateRef St,
438  SymbolRef Sym) const {
439  const ConstraintRangeTy::data_type *T = St->get<ConstraintRange>(Sym);
440  return T ? T->getConcreteValue() : nullptr;
441 }
442 
443 /// Scan all symbols referenced by the constraints. If the symbol is not alive
444 /// as marked in LSymbols, mark it as dead in DSymbols.
446 RangeConstraintManager::removeDeadBindings(ProgramStateRef State,
447  SymbolReaper &SymReaper) {
448  bool Changed = false;
449  ConstraintRangeTy CR = State->get<ConstraintRange>();
450  ConstraintRangeTy::Factory &CRFactory = State->get_context<ConstraintRange>();
451 
452  for (ConstraintRangeTy::iterator I = CR.begin(), E = CR.end(); I != E; ++I) {
453  SymbolRef Sym = I.getKey();
454  if (SymReaper.maybeDead(Sym)) {
455  Changed = true;
456  CR = CRFactory.remove(CR, Sym);
457  }
458  }
459 
460  return Changed ? State->set<ConstraintRange>(CR) : State;
461 }
462 
463 RangeSet RangeConstraintManager::getRange(ProgramStateRef State,
464  SymbolRef Sym) {
465  if (ConstraintRangeTy::data_type *V = State->get<ConstraintRange>(Sym))
466  return *V;
467 
468  // Lazily generate a new RangeSet representing all possible values for the
469  // given symbol type.
470  BasicValueFactory &BV = getBasicVals();
471  QualType T = Sym->getType();
472 
473  RangeSet Result(F, BV.getMinValue(T), BV.getMaxValue(T));
474 
475  // Special case: references are known to be non-zero.
476  if (T->isReferenceType()) {
477  APSIntType IntType = BV.getAPSIntType(T);
478  Result = Result.Intersect(BV, F, ++IntType.getZeroValue(),
479  --IntType.getZeroValue());
480  }
481 
482  return Result;
483 }
484 
485 //===------------------------------------------------------------------------===
486 // assumeSymX methods: protected interface for RangeConstraintManager.
487 //===------------------------------------------------------------------------===/
488 
489 // The syntax for ranges below is mathematical, using [x, y] for closed ranges
490 // and (x, y) for open ranges. These ranges are modular, corresponding with
491 // a common treatment of C integer overflow. This means that these methods
492 // do not have to worry about overflow; RangeSet::Intersect can handle such a
493 // "wraparound" range.
494 // As an example, the range [UINT_MAX-1, 3) contains five values: UINT_MAX-1,
495 // UINT_MAX, 0, 1, and 2.
496 
498 RangeConstraintManager::assumeSymNE(ProgramStateRef St, SymbolRef Sym,
499  const llvm::APSInt &Int,
500  const llvm::APSInt &Adjustment) {
501  // Before we do any real work, see if the value can even show up.
502  APSIntType AdjustmentType(Adjustment);
503  if (AdjustmentType.testInRange(Int, true) != APSIntType::RTR_Within)
504  return St;
505 
506  llvm::APSInt Lower = AdjustmentType.convert(Int) - Adjustment;
507  llvm::APSInt Upper = Lower;
508  --Lower;
509  ++Upper;
510 
511  // [Int-Adjustment+1, Int-Adjustment-1]
512  // Notice that the lower bound is greater than the upper bound.
513  RangeSet New = getRange(St, Sym).Intersect(getBasicVals(), F, Upper, Lower);
514  return New.isEmpty() ? nullptr : St->set<ConstraintRange>(Sym, New);
515 }
516 
518 RangeConstraintManager::assumeSymEQ(ProgramStateRef St, SymbolRef Sym,
519  const llvm::APSInt &Int,
520  const llvm::APSInt &Adjustment) {
521  // Before we do any real work, see if the value can even show up.
522  APSIntType AdjustmentType(Adjustment);
523  if (AdjustmentType.testInRange(Int, true) != APSIntType::RTR_Within)
524  return nullptr;
525 
526  // [Int-Adjustment, Int-Adjustment]
527  llvm::APSInt AdjInt = AdjustmentType.convert(Int) - Adjustment;
528  RangeSet New = getRange(St, Sym).Intersect(getBasicVals(), F, AdjInt, AdjInt);
529  return New.isEmpty() ? nullptr : St->set<ConstraintRange>(Sym, New);
530 }
531 
532 RangeSet RangeConstraintManager::getSymLTRange(ProgramStateRef St,
533  SymbolRef Sym,
534  const llvm::APSInt &Int,
535  const llvm::APSInt &Adjustment) {
536  // Before we do any real work, see if the value can even show up.
537  APSIntType AdjustmentType(Adjustment);
538  switch (AdjustmentType.testInRange(Int, true)) {
540  return F.getEmptySet();
542  break;
544  return getRange(St, Sym);
545  }
546 
547  // Special case for Int == Min. This is always false.
548  llvm::APSInt ComparisonVal = AdjustmentType.convert(Int);
549  llvm::APSInt Min = AdjustmentType.getMinValue();
550  if (ComparisonVal == Min)
551  return F.getEmptySet();
552 
553  llvm::APSInt Lower = Min - Adjustment;
554  llvm::APSInt Upper = ComparisonVal - Adjustment;
555  --Upper;
556 
557  return getRange(St, Sym).Intersect(getBasicVals(), F, Lower, Upper);
558 }
559 
561 RangeConstraintManager::assumeSymLT(ProgramStateRef St, SymbolRef Sym,
562  const llvm::APSInt &Int,
563  const llvm::APSInt &Adjustment) {
564  RangeSet New = getSymLTRange(St, Sym, Int, Adjustment);
565  return New.isEmpty() ? nullptr : St->set<ConstraintRange>(Sym, New);
566 }
567 
568 RangeSet RangeConstraintManager::getSymGTRange(ProgramStateRef St,
569  SymbolRef Sym,
570  const llvm::APSInt &Int,
571  const llvm::APSInt &Adjustment) {
572  // Before we do any real work, see if the value can even show up.
573  APSIntType AdjustmentType(Adjustment);
574  switch (AdjustmentType.testInRange(Int, true)) {
576  return getRange(St, Sym);
578  break;
580  return F.getEmptySet();
581  }
582 
583  // Special case for Int == Max. This is always false.
584  llvm::APSInt ComparisonVal = AdjustmentType.convert(Int);
585  llvm::APSInt Max = AdjustmentType.getMaxValue();
586  if (ComparisonVal == Max)
587  return F.getEmptySet();
588 
589  llvm::APSInt Lower = ComparisonVal - Adjustment;
590  llvm::APSInt Upper = Max - Adjustment;
591  ++Lower;
592 
593  return getRange(St, Sym).Intersect(getBasicVals(), F, Lower, Upper);
594 }
595 
597 RangeConstraintManager::assumeSymGT(ProgramStateRef St, SymbolRef Sym,
598  const llvm::APSInt &Int,
599  const llvm::APSInt &Adjustment) {
600  RangeSet New = getSymGTRange(St, Sym, Int, Adjustment);
601  return New.isEmpty() ? nullptr : St->set<ConstraintRange>(Sym, New);
602 }
603 
604 RangeSet RangeConstraintManager::getSymGERange(ProgramStateRef St,
605  SymbolRef Sym,
606  const llvm::APSInt &Int,
607  const llvm::APSInt &Adjustment) {
608  // Before we do any real work, see if the value can even show up.
609  APSIntType AdjustmentType(Adjustment);
610  switch (AdjustmentType.testInRange(Int, true)) {
612  return getRange(St, Sym);
614  break;
616  return F.getEmptySet();
617  }
618 
619  // Special case for Int == Min. This is always feasible.
620  llvm::APSInt ComparisonVal = AdjustmentType.convert(Int);
621  llvm::APSInt Min = AdjustmentType.getMinValue();
622  if (ComparisonVal == Min)
623  return getRange(St, Sym);
624 
625  llvm::APSInt Max = AdjustmentType.getMaxValue();
626  llvm::APSInt Lower = ComparisonVal - Adjustment;
627  llvm::APSInt Upper = Max - Adjustment;
628 
629  return getRange(St, Sym).Intersect(getBasicVals(), F, Lower, Upper);
630 }
631 
633 RangeConstraintManager::assumeSymGE(ProgramStateRef St, SymbolRef Sym,
634  const llvm::APSInt &Int,
635  const llvm::APSInt &Adjustment) {
636  RangeSet New = getSymGERange(St, Sym, Int, Adjustment);
637  return New.isEmpty() ? nullptr : St->set<ConstraintRange>(Sym, New);
638 }
639 
640 RangeSet RangeConstraintManager::getSymLERange(const RangeSet &RS,
641  const llvm::APSInt &Int,
642  const llvm::APSInt &Adjustment) {
643  // Before we do any real work, see if the value can even show up.
644  APSIntType AdjustmentType(Adjustment);
645  switch (AdjustmentType.testInRange(Int, true)) {
647  return F.getEmptySet();
649  break;
651  return RS;
652  }
653 
654  // Special case for Int == Max. This is always feasible.
655  llvm::APSInt ComparisonVal = AdjustmentType.convert(Int);
656  llvm::APSInt Max = AdjustmentType.getMaxValue();
657  if (ComparisonVal == Max)
658  return RS;
659 
660  llvm::APSInt Min = AdjustmentType.getMinValue();
661  llvm::APSInt Lower = Min - Adjustment;
662  llvm::APSInt Upper = ComparisonVal - Adjustment;
663 
664  return RS.Intersect(getBasicVals(), F, Lower, Upper);
665 }
666 
667 RangeSet RangeConstraintManager::getSymLERange(ProgramStateRef St,
668  SymbolRef Sym,
669  const llvm::APSInt &Int,
670  const llvm::APSInt &Adjustment) {
671  // Before we do any real work, see if the value can even show up.
672  APSIntType AdjustmentType(Adjustment);
673  switch (AdjustmentType.testInRange(Int, true)) {
675  return F.getEmptySet();
677  break;
679  return getRange(St, Sym);
680  }
681 
682  // Special case for Int == Max. This is always feasible.
683  llvm::APSInt ComparisonVal = AdjustmentType.convert(Int);
684  llvm::APSInt Max = AdjustmentType.getMaxValue();
685  if (ComparisonVal == Max)
686  return getRange(St, Sym);
687 
688  llvm::APSInt Min = AdjustmentType.getMinValue();
689  llvm::APSInt Lower = Min - Adjustment;
690  llvm::APSInt Upper = ComparisonVal - Adjustment;
691 
692  return getRange(St, Sym).Intersect(getBasicVals(), F, Lower, Upper);
693 }
694 
696 RangeConstraintManager::assumeSymLE(ProgramStateRef St, SymbolRef Sym,
697  const llvm::APSInt &Int,
698  const llvm::APSInt &Adjustment) {
699  RangeSet New = getSymLERange(St, Sym, Int, Adjustment);
700  return New.isEmpty() ? nullptr : St->set<ConstraintRange>(Sym, New);
701 }
702 
703 ProgramStateRef RangeConstraintManager::assumeSymWithinInclusiveRange(
704  ProgramStateRef State, SymbolRef Sym, const llvm::APSInt &From,
705  const llvm::APSInt &To, const llvm::APSInt &Adjustment) {
706  RangeSet New = getSymGERange(State, Sym, From, Adjustment);
707  if (New.isEmpty())
708  return nullptr;
709  New = getSymLERange(New, To, Adjustment);
710  return New.isEmpty() ? nullptr : State->set<ConstraintRange>(Sym, New);
711 }
712 
713 ProgramStateRef RangeConstraintManager::assumeSymOutsideInclusiveRange(
714  ProgramStateRef State, SymbolRef Sym, const llvm::APSInt &From,
715  const llvm::APSInt &To, const llvm::APSInt &Adjustment) {
716  RangeSet RangeLT = getSymLTRange(State, Sym, From, Adjustment);
717  RangeSet RangeGT = getSymGTRange(State, Sym, To, Adjustment);
718  RangeSet New(RangeLT.addRange(F, RangeGT));
719  return New.isEmpty() ? nullptr : State->set<ConstraintRange>(Sym, New);
720 }
721 
722 //===------------------------------------------------------------------------===
723 // Pretty-printing.
724 //===------------------------------------------------------------------------===/
725 
726 void RangeConstraintManager::print(ProgramStateRef St, raw_ostream &Out,
727  const char *nl, const char *sep) {
728 
729  ConstraintRangeTy Ranges = St->get<ConstraintRange>();
730 
731  if (Ranges.isEmpty()) {
732  Out << nl << sep << "Ranges are empty." << nl;
733  return;
734  }
735 
736  Out << nl << sep << "Ranges of symbol values:";
737  for (ConstraintRangeTy::iterator I = Ranges.begin(), E = Ranges.end(); I != E;
738  ++I) {
739  Out << nl << ' ' << I.getKey() << " : ";
740  I.getData().print(Out);
741  }
742  Out << nl;
743 }
A (possibly-)qualified type.
Definition: Type.h:613
Value is less than the minimum representable value.
Definition: APSIntType.h:78
bool operator==(CanQual< T > x, CanQual< U > y)
DominatorTree GraphTraits specialization so the DominatorTree can be iterable by generic graph iterat...
Definition: Dominators.h:26
bool maybeDead(SymbolRef sym)
If a symbol is known to be live, marks the symbol as live.
std::unique_ptr< ConstraintManager > CreateRangeConstraintManager(ProgramStateManager &statemgr, SubEngine *subengine)
The base class of the type hierarchy.
Definition: Type.h:1300
Symbolic value.
Definition: SymExpr.h:29
LineState State
Definition: Format.h:1628
bool isReferenceType() const
Definition: Type.h:5703
static bool isLocType(QualType T)
Definition: SVals.h:307
Value is representable using this type.
Definition: APSIntType.h:79
A record of the "type" of an APSInt, used for conversions.
Definition: APSIntType.h:20
Represents a symbolic expression like &#39;x&#39; + 3.
RangeTestResultKind testInRange(const llvm::APSInt &Val, bool AllowMixedSign) const LLVM_READONLY
Tests whether a given value is losslessly representable using this type.
Definition: APSIntType.cpp:16
llvm::APSInt getZeroValue() const LLVM_READONLY
Returns an all-zero value for this type.
Definition: APSIntType.h:56
virtual QualType getType() const =0
ID
Defines the address space values used by the address space qualifier of QualType. ...
Definition: AddressSpaces.h:26
llvm::APSInt getMinValue() const LLVM_READONLY
Returns the minimum value for this type.
Definition: APSIntType.h:61
REGISTER_TRAIT_WITH_PROGRAMSTATE(ConstraintRange, CLANG_ENTO_PROGRAMSTATE_MAP(SymbolRef, RangeSet)) namespace
The result type of a method or function.
do v
Definition: arm_acle.h:78
Optional< T > getAs() const
Convert to the specified SVal type, returning None if this SVal is not of the desired type...
Definition: SVals.h:100
bool isComparisonOp() const
Definition: Expr.h:3058
llvm::APSInt getMaxValue() const LLVM_READONLY
Returns the maximum value for this type.
Definition: APSIntType.h:66
SVal - This represents a symbolic expression, which can be either an L-value or an R-value...
Definition: SVals.h:63
#define CLANG_ENTO_PROGRAMSTATE_MAP(Key, Value)
Helper for registering a map trait.
A class responsible for cleaning up unused symbols.
Value is greater than the maximum representable value.
Definition: APSIntType.h:80
RangeTestResultKind
Used to classify whether a value is representable using this type.
Definition: APSIntType.h:77
llvm::APSInt convert(const llvm::APSInt &Value) const LLVM_READONLY
Convert and return a new APSInt with the given value, but this type&#39;s bit width and signedness...
Definition: APSIntType.h:49
/file This file defines classes for searching and anlyzing source code clones.
Represents symbolic expression.
Definition: SVals.h:326
const llvm::APSInt & getMinValue(const llvm::APSInt &v)
APSIntType getAPSIntType(QualType T) const
Returns the type of the APSInt used to store values of the given QualType.
X
Add a minimal nested name specifier fixit hint to allow lookup of a tag name from an outer enclosing ...
Definition: SemaDecl.cpp:12794
const llvm::APSInt & getMaxValue(const llvm::APSInt &v)
Represents a symbolic expression like &#39;x&#39; + &#39;y&#39;.