From 684045e9e843ed9b8be30728482ce3d69d63b527 Mon Sep 17 00:00:00 2001 From: "Zancanaro; Carlo" Date: Thu, 4 Oct 2012 17:11:33 +1000 Subject: Lets keep trying with this here equation system. Still not there, but more non-functional code is there. Splitting blocks into sub-blocks now works, as does some of the guard stuff and the general "shape" of the resulting equation system. --- .../Core/IntervalConstraintManager.cpp | 442 +++++++++++++++++++++ 1 file changed, 442 insertions(+) create mode 100644 clang/lib/StaticAnalyzer/Core/IntervalConstraintManager.cpp (limited to 'clang/lib/StaticAnalyzer/Core/IntervalConstraintManager.cpp') diff --git a/clang/lib/StaticAnalyzer/Core/IntervalConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/IntervalConstraintManager.cpp new file mode 100644 index 0000000..9d04720 --- /dev/null +++ b/clang/lib/StaticAnalyzer/Core/IntervalConstraintManager.cpp @@ -0,0 +1,442 @@ +//== IntervalConstraintManager.cpp - Manage range constraints.------*- C++ -*--==// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file defines IntervalConstraintManager, a class that tracks simple +// equality and inequality constraints on symbolic values of ProgramState. +// +//===----------------------------------------------------------------------===// + +#include "SimpleConstraintManager.h" +#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" +#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h" +#include "llvm/Support/Debug.h" +#include "llvm/ADT/FoldingSet.h" +#include "llvm/ADT/ImmutableSet.h" +#include "llvm/Support/raw_ostream.h" + +using namespace clang; +using namespace ento; + +namespace { class ConstraintRange {}; } +static int ConstraintRangeIndex = 0; + +/// A Range represents the closed range [from, to]. The caller must +/// guarantee that from <= to. Note that Range is immutable, so as not +/// to subvert RangeSet's immutability. +namespace { +class Range : public std::pair { +public: + Range(const llvm::APSInt &from, const llvm::APSInt &to) + : std::pair(&from, &to) { + assert(from <= to); + } + bool Includes(const llvm::APSInt &v) const { + return *first <= v && v <= *second; + } + const llvm::APSInt &From() const { + return *first; + } + const llvm::APSInt &To() const { + return *second; + } + const llvm::APSInt *getConcreteValue() const { + return &From() == &To() ? &From() : NULL; + } + + void Profile(llvm::FoldingSetNodeID &ID) const { + ID.AddPointer(&From()); + ID.AddPointer(&To()); + } +}; + + +class RangeTrait : public llvm::ImutContainerInfo { +public: + // When comparing if one Range is less than another, we should compare + // the actual APSInt values instead of their pointers. This keeps the order + // consistent (instead of comparing by pointer values) and can potentially + // be used to speed up some of the operations in RangeSet. + static inline bool isLess(key_type_ref lhs, key_type_ref rhs) { + return *lhs.first < *rhs.first || (!(*rhs.first < *lhs.first) && + *lhs.second < *rhs.second); + } +}; + +/// RangeSet contains a set of ranges. If the set is empty, then +/// there the value of a symbol is overly constrained and there are no +/// possible values for that symbol. +class RangeSet { + typedef llvm::ImmutableSet PrimRangeSet; + PrimRangeSet ranges; // no need to make const, since it is an + // ImmutableSet - this allows default operator= + // to work. +public: + typedef PrimRangeSet::Factory Factory; + typedef PrimRangeSet::iterator iterator; + + RangeSet(PrimRangeSet RS) : ranges(RS) {} + + iterator begin() const { return ranges.begin(); } + iterator end() const { return ranges.end(); } + + bool isEmpty() const { return ranges.isEmpty(); } + + /// Construct a new RangeSet representing '{ [from, to] }'. + RangeSet(Factory &F, const llvm::APSInt &from, const llvm::APSInt &to) + : ranges(F.add(F.getEmptySet(), Range(from, to))) {} + + /// Profile - Generates a hash profile of this RangeSet for use + /// by FoldingSet. + void Profile(llvm::FoldingSetNodeID &ID) const { ranges.Profile(ID); } + + /// getConcreteValue - If a symbol is contrained to equal a specific integer + /// constant then this method returns that value. Otherwise, it returns + /// NULL. + const llvm::APSInt* getConcreteValue() const { + return ranges.isSingleton() ? ranges.begin()->getConcreteValue() : 0; + } + +private: + void IntersectInRange(BasicValueFactory &BV, Factory &F, + const llvm::APSInt &Lower, + const llvm::APSInt &Upper, + PrimRangeSet &newRanges, + PrimRangeSet::iterator &i, + PrimRangeSet::iterator &e) const { + // There are six cases for each range R in the set: + // 1. R is entirely before the intersection range. + // 2. R is entirely after the intersection range. + // 3. R contains the entire intersection range. + // 4. R starts before the intersection range and ends in the middle. + // 5. R starts in the middle of the intersection range and ends after it. + // 6. R is entirely contained in the intersection range. + // These correspond to each of the conditions below. + for (/* i = begin(), e = end() */; i != e; ++i) { + if (i->To() < Lower) { + continue; + } + if (i->From() > Upper) { + break; + } + + if (i->Includes(Lower)) { + if (i->Includes(Upper)) { + newRanges = F.add(newRanges, Range(BV.getValue(Lower), + BV.getValue(Upper))); + break; + } else + newRanges = F.add(newRanges, Range(BV.getValue(Lower), i->To())); + } else { + if (i->Includes(Upper)) { + newRanges = F.add(newRanges, Range(i->From(), BV.getValue(Upper))); + break; + } else + newRanges = F.add(newRanges, *i); + } + } + } + +public: + // Returns a set containing the values in the receiving set, intersected with + // the closed range [Lower, Upper]. Unlike the Range type, this range uses + // modular arithmetic, corresponding to the common treatment of C integer + // overflow. Thus, if the Lower bound is greater than the Upper bound, the + // range is taken to wrap around. This is equivalent to taking the + // intersection with the two ranges [Min, Upper] and [Lower, Max], + // or, alternatively, /removing/ all integers between Upper and Lower. + RangeSet Intersect(BasicValueFactory &BV, Factory &F, + const llvm::APSInt &Lower, + const llvm::APSInt &Upper) const { + PrimRangeSet newRanges = F.getEmptySet(); + + PrimRangeSet::iterator i = begin(), e = end(); + if (Lower <= Upper) + IntersectInRange(BV, F, Lower, Upper, newRanges, i, e); + else { + // The order of the next two statements is important! + // IntersectInRange() does not reset the iteration state for i and e. + // Therefore, the lower range most be handled first. + IntersectInRange(BV, F, BV.getMinValue(Upper), Upper, newRanges, i, e); + IntersectInRange(BV, F, Lower, BV.getMaxValue(Lower), newRanges, i, e); + } + return newRanges; + } + + void print(raw_ostream &os) const { + bool isFirst = true; + os << "{ "; + for (iterator i = begin(), e = end(); i != e; ++i) { + if (isFirst) + isFirst = false; + else + os << ", "; + + os << '[' << i->From().toString(10) << ", " << i->To().toString(10) + << ']'; + } + os << " }"; + } + + bool operator==(const RangeSet &other) const { + return ranges == other.ranges; + } +}; +} // end anonymous namespace + +typedef llvm::ImmutableMap ConstraintRangeTy; + +namespace clang { +namespace ento { +template<> +struct ProgramStateTrait + : public ProgramStatePartialTrait { + static inline void *GDMIndex() { return &ConstraintRangeIndex; } +}; +} +} + +namespace { +class IntervalConstraintManager : public SimpleConstraintManager{ + RangeSet GetRange(ProgramStateRef state, SymbolRef sym); +public: + IntervalConstraintManager(SubEngine &subengine) + : SimpleConstraintManager(subengine) {} + + ProgramStateRef assumeSymNE(ProgramStateRef state, SymbolRef sym, + const llvm::APSInt& Int, + const llvm::APSInt& Adjustment); + + ProgramStateRef assumeSymEQ(ProgramStateRef state, SymbolRef sym, + const llvm::APSInt& Int, + const llvm::APSInt& Adjustment); + + ProgramStateRef assumeSymLT(ProgramStateRef state, SymbolRef sym, + const llvm::APSInt& Int, + const llvm::APSInt& Adjustment); + + ProgramStateRef assumeSymGT(ProgramStateRef state, SymbolRef sym, + const llvm::APSInt& Int, + const llvm::APSInt& Adjustment); + + ProgramStateRef assumeSymGE(ProgramStateRef state, SymbolRef sym, + const llvm::APSInt& Int, + const llvm::APSInt& Adjustment); + + ProgramStateRef assumeSymLE(ProgramStateRef state, SymbolRef sym, + const llvm::APSInt& Int, + const llvm::APSInt& Adjustment); + + const llvm::APSInt* getSymVal(ProgramStateRef St, SymbolRef sym) const; + + // FIXME: Refactor into SimpleConstraintManager? + bool isEqual(ProgramStateRef St, SymbolRef sym, const llvm::APSInt& V) const { + const llvm::APSInt *i = getSymVal(St, sym); + return i ? *i == V : false; + } + + ProgramStateRef removeDeadBindings(ProgramStateRef St, SymbolReaper& SymReaper); + + void print(ProgramStateRef St, raw_ostream &Out, + const char* nl, const char *sep); + +private: + RangeSet::Factory F; +}; + +} // end anonymous namespace + +ConstraintManager* ento::CreateIntervalConstraintManager(ProgramStateManager&, + SubEngine &subeng) { + return new IntervalConstraintManager(subeng); +} + +const llvm::APSInt* IntervalConstraintManager::getSymVal(ProgramStateRef St, + SymbolRef sym) const { + const ConstraintRangeTy::data_type *T = St->get(sym); + return T ? T->getConcreteValue() : NULL; +} + +/// Scan all symbols referenced by the constraints. If the symbol is not alive +/// as marked in LSymbols, mark it as dead in DSymbols. +ProgramStateRef +IntervalConstraintManager::removeDeadBindings(ProgramStateRef state, + SymbolReaper& SymReaper) { + + ConstraintRangeTy CR = state->get(); + ConstraintRangeTy::Factory& CRFactory = state->get_context(); + + for (ConstraintRangeTy::iterator I = CR.begin(), E = CR.end(); I != E; ++I) { + SymbolRef sym = I.getKey(); + if (SymReaper.maybeDead(sym)) + CR = CRFactory.remove(CR, sym); + } + + return state->set(CR); +} + +RangeSet +IntervalConstraintManager::GetRange(ProgramStateRef state, SymbolRef sym) { + if (ConstraintRangeTy::data_type* V = state->get(sym)) + return *V; + + // Lazily generate a new RangeSet representing all possible values for the + // given symbol type. + QualType T = state->getSymbolManager().getType(sym); + BasicValueFactory& BV = state->getBasicVals(); + return RangeSet(F, BV.getMinValue(T), BV.getMaxValue(T)); +} + +//===------------------------------------------------------------------------=== +// assumeSymX methods: public interface for IntervalConstraintManager. +//===------------------------------------------------------------------------===/ + +// The syntax for ranges below is mathematical, using [x, y] for closed ranges +// and (x, y) for open ranges. These ranges are modular, corresponding with +// a common treatment of C integer overflow. This means that these methods +// do not have to worry about overflow; RangeSet::Intersect can handle such a +// "wraparound" range. +// As an example, the range [UINT_MAX-1, 3) contains five values: UINT_MAX-1, +// UINT_MAX, 0, 1, and 2. + +ProgramStateRef +IntervalConstraintManager::assumeSymNE(ProgramStateRef state, SymbolRef sym, + const llvm::APSInt& Int, + const llvm::APSInt& Adjustment) { + BasicValueFactory &BV = state->getBasicVals(); + + llvm::APSInt Lower = Int-Adjustment; + llvm::APSInt Upper = Lower; + --Lower; + ++Upper; + + // [Int-Adjustment+1, Int-Adjustment-1] + // Notice that the lower bound is greater than the upper bound. + RangeSet New = GetRange(state, sym).Intersect(BV, F, Upper, Lower); + return New.isEmpty() ? NULL : state->set(sym, New); +} + +ProgramStateRef +IntervalConstraintManager::assumeSymEQ(ProgramStateRef state, SymbolRef sym, + const llvm::APSInt& Int, + const llvm::APSInt& Adjustment) { + // [Int-Adjustment, Int-Adjustment] + BasicValueFactory &BV = state->getBasicVals(); + llvm::APSInt AdjInt = Int-Adjustment; + RangeSet New = GetRange(state, sym).Intersect(BV, F, AdjInt, AdjInt); + return New.isEmpty() ? NULL : state->set(sym, New); +} + +ProgramStateRef +IntervalConstraintManager::assumeSymLT(ProgramStateRef state, SymbolRef sym, + const llvm::APSInt& Int, + const llvm::APSInt& Adjustment) { + BasicValueFactory &BV = state->getBasicVals(); + + QualType T = state->getSymbolManager().getType(sym); + const llvm::APSInt &Min = BV.getMinValue(T); + + // Special case for Int == Min. This is always false. + if (Int == Min) + return NULL; + + llvm::APSInt Lower = Min-Adjustment; + llvm::APSInt Upper = Int-Adjustment; + --Upper; + + RangeSet New = GetRange(state, sym).Intersect(BV, F, Lower, Upper); + return New.isEmpty() ? NULL : state->set(sym, New); +} + +ProgramStateRef +IntervalConstraintManager::assumeSymGT(ProgramStateRef state, SymbolRef sym, + const llvm::APSInt& Int, + const llvm::APSInt& Adjustment) { + BasicValueFactory &BV = state->getBasicVals(); + + QualType T = state->getSymbolManager().getType(sym); + const llvm::APSInt &Max = BV.getMaxValue(T); + + // Special case for Int == Max. This is always false. + if (Int == Max) + return NULL; + + llvm::APSInt Lower = Int-Adjustment; + llvm::APSInt Upper = Max-Adjustment; + ++Lower; + + RangeSet New = GetRange(state, sym).Intersect(BV, F, Lower, Upper); + return New.isEmpty() ? NULL : state->set(sym, New); +} + +ProgramStateRef +IntervalConstraintManager::assumeSymGE(ProgramStateRef state, SymbolRef sym, + const llvm::APSInt& Int, + const llvm::APSInt& Adjustment) { + BasicValueFactory &BV = state->getBasicVals(); + + QualType T = state->getSymbolManager().getType(sym); + const llvm::APSInt &Min = BV.getMinValue(T); + + // Special case for Int == Min. This is always feasible. + if (Int == Min) + return state; + + const llvm::APSInt &Max = BV.getMaxValue(T); + + llvm::APSInt Lower = Int-Adjustment; + llvm::APSInt Upper = Max-Adjustment; + + RangeSet New = GetRange(state, sym).Intersect(BV, F, Lower, Upper); + return New.isEmpty() ? NULL : state->set(sym, New); +} + +ProgramStateRef +IntervalConstraintManager::assumeSymLE(ProgramStateRef state, SymbolRef sym, + const llvm::APSInt& Int, + const llvm::APSInt& Adjustment) { + BasicValueFactory &BV = state->getBasicVals(); + + QualType T = state->getSymbolManager().getType(sym); + const llvm::APSInt &Max = BV.getMaxValue(T); + + // Special case for Int == Max. This is always feasible. + if (Int == Max) + return state; + + const llvm::APSInt &Min = BV.getMinValue(T); + + llvm::APSInt Lower = Min-Adjustment; + llvm::APSInt Upper = Int-Adjustment; + + RangeSet New = GetRange(state, sym).Intersect(BV, F, Lower, Upper); + return New.isEmpty() ? NULL : state->set(sym, New); +} + +//===------------------------------------------------------------------------=== +// Pretty-printing. +//===------------------------------------------------------------------------===/ + +void IntervalConstraintManager::print(ProgramStateRef St, raw_ostream &Out, + const char* nl, const char *sep) { + + ConstraintRangeTy Ranges = St->get(); + + if (Ranges.isEmpty()) { + Out << nl << sep << "Ranges are empty." << nl; + return; + } + + Out << nl << sep << "Ranges of symbol values:"; + for (ConstraintRangeTy::iterator I=Ranges.begin(), E=Ranges.end(); I!=E; ++I){ + Out << nl << ' ' << I.getKey() << " : "; + I.getData().print(Out); + } + Out << nl; +} -- cgit v1.2.3