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//== RangeConstraintManager.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 RangeConstraintManager, a class that tracks simple
// equality and inequality constraints on symbolic values of GRState.
//
//===----------------------------------------------------------------------===//
#include "SimpleConstraintManager.h"
#include "clang/Checker/PathSensitive/GRState.h"
#include "clang/Checker/PathSensitive/GRStateTrait.h"
#include "clang/Checker/PathSensitive/GRTransferFuncs.h"
#include "clang/Checker/ManagerRegistry.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;
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<const llvm::APSInt*,
const llvm::APSInt*> {
public:
Range(const llvm::APSInt &from, const llvm::APSInt &to)
: std::pair<const llvm::APSInt*, const llvm::APSInt*>(&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<Range> {
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<Range, RangeTrait> 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) {}
RangeSet(Factory& F) : ranges(F.GetEmptySet()) {}
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;
}
/// AddEQ - Create a new RangeSet with the additional constraint that the
/// value be equal to V.
RangeSet AddEQ(BasicValueFactory &BV, Factory &F, const llvm::APSInt &V) {
// Search for a range that includes 'V'. If so, return a new RangeSet
// representing { [V, V] }.
for (PrimRangeSet::iterator i = begin(), e = end(); i!=e; ++i)
if (i->Includes(V))
return RangeSet(F, V, V);
return RangeSet(F);
}
/// AddNE - Create a new RangeSet with the additional constraint that the
/// value be not be equal to V.
RangeSet AddNE(BasicValueFactory &BV, Factory &F, const llvm::APSInt &V) {
PrimRangeSet newRanges = ranges;
// FIXME: We can perhaps enhance ImmutableSet to do this search for us
// in log(N) time using the sorted property of the internal AVL tree.
for (iterator i = begin(), e = end(); i != e; ++i) {
if (i->Includes(V)) {
// Remove the old range.
newRanges = F.Remove(newRanges, *i);
// Split the old range into possibly one or two ranges.
if (V != i->From())
newRanges = F.Add(newRanges, Range(i->From(), BV.Sub1(V)));
if (V != i->To())
newRanges = F.Add(newRanges, Range(BV.Add1(V), i->To()));
// All of the ranges are non-overlapping, so we can stop.
break;
}
}
return newRanges;
}
/// AddNE - Create a new RangeSet with the additional constraint that the
/// value be less than V.
RangeSet AddLT(BasicValueFactory &BV, Factory &F, const llvm::APSInt &V) {
PrimRangeSet newRanges = F.GetEmptySet();
for (iterator i = begin(), e = end() ; i != e ; ++i) {
if (i->Includes(V) && i->From() < V)
newRanges = F.Add(newRanges, Range(i->From(), BV.Sub1(V)));
else if (i->To() < V)
newRanges = F.Add(newRanges, *i);
}
return newRanges;
}
RangeSet AddLE(BasicValueFactory &BV, Factory &F, const llvm::APSInt &V) {
PrimRangeSet newRanges = F.GetEmptySet();
for (iterator i = begin(), e = end(); i != e; ++i) {
// Strictly we should test for includes *V + 1, but no harm is
// done by this formulation
if (i->Includes(V))
newRanges = F.Add(newRanges, Range(i->From(), V));
else if (i->To() <= V)
newRanges = F.Add(newRanges, *i);
}
return newRanges;
}
RangeSet AddGT(BasicValueFactory &BV, Factory &F, const llvm::APSInt &V) {
PrimRangeSet newRanges = F.GetEmptySet();
for (PrimRangeSet::iterator i = begin(), e = end(); i != e; ++i) {
if (i->Includes(V) && i->To() > V)
newRanges = F.Add(newRanges, Range(BV.Add1(V), i->To()));
else if (i->From() > V)
newRanges = F.Add(newRanges, *i);
}
return newRanges;
}
RangeSet AddGE(BasicValueFactory &BV, Factory &F, const llvm::APSInt &V) {
PrimRangeSet newRanges = F.GetEmptySet();
for (PrimRangeSet::iterator i = begin(), e = end(); i != e; ++i) {
// Strictly we should test for includes *V - 1, but no harm is
// done by this formulation
if (i->Includes(V))
newRanges = F.Add(newRanges, Range(V, i->To()));
else if (i->From() >= V)
newRanges = F.Add(newRanges, *i);
}
return newRanges;
}
void print(llvm::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<SymbolRef,RangeSet> ConstraintRangeTy;
namespace clang {
template<>
struct GRStateTrait<ConstraintRange>
: public GRStatePartialTrait<ConstraintRangeTy> {
static inline void* GDMIndex() { return &ConstraintRangeIndex; }
};
}
namespace {
class RangeConstraintManager : public SimpleConstraintManager{
RangeSet GetRange(const GRState *state, SymbolRef sym);
public:
RangeConstraintManager(GRSubEngine &subengine)
: SimpleConstraintManager(subengine) {}
const GRState* AssumeSymNE(const GRState* St, SymbolRef sym,
const llvm::APSInt& V);
const GRState* AssumeSymEQ(const GRState* St, SymbolRef sym,
const llvm::APSInt& V);
const GRState* AssumeSymLT(const GRState* St, SymbolRef sym,
const llvm::APSInt& V);
const GRState* AssumeSymGT(const GRState* St, SymbolRef sym,
const llvm::APSInt& V);
const GRState* AssumeSymGE(const GRState* St, SymbolRef sym,
const llvm::APSInt& V);
const GRState* AssumeSymLE(const GRState* St, SymbolRef sym,
const llvm::APSInt& V);
const llvm::APSInt* getSymVal(const GRState* St, SymbolRef sym) const;
// FIXME: Refactor into SimpleConstraintManager?
bool isEqual(const GRState* St, SymbolRef sym, const llvm::APSInt& V) const {
const llvm::APSInt *i = getSymVal(St, sym);
return i ? *i == V : false;
}
const GRState* RemoveDeadBindings(const GRState* St, SymbolReaper& SymReaper);
void print(const GRState* St, llvm::raw_ostream& Out,
const char* nl, const char *sep);
private:
RangeSet::Factory F;
};
} // end anonymous namespace
ConstraintManager* clang::CreateRangeConstraintManager(GRStateManager&,
GRSubEngine &subeng) {
return new RangeConstraintManager(subeng);
}
const llvm::APSInt* RangeConstraintManager::getSymVal(const GRState* St,
SymbolRef sym) const {
const ConstraintRangeTy::data_type *T = St->get<ConstraintRange>(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.
const GRState*
RangeConstraintManager::RemoveDeadBindings(const GRState* state,
SymbolReaper& SymReaper) {
ConstraintRangeTy CR = state->get<ConstraintRange>();
ConstraintRangeTy::Factory& CRFactory = state->get_context<ConstraintRange>();
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<ConstraintRange>(CR);
}
//===------------------------------------------------------------------------===
// AssumeSymX methods: public interface for RangeConstraintManager.
//===------------------------------------------------------------------------===/
RangeSet
RangeConstraintManager::GetRange(const GRState *state, SymbolRef sym) {
if (ConstraintRangeTy::data_type* V = state->get<ConstraintRange>(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 RangeConstraintManager.
//===------------------------------------------------------------------------===/
#define AssumeX(OP)\
const GRState*\
RangeConstraintManager::AssumeSym ## OP(const GRState* state, SymbolRef sym,\
const llvm::APSInt& V){\
const RangeSet& R = GetRange(state, sym).Add##OP(state->getBasicVals(), F, V);\
return !R.isEmpty() ? state->set<ConstraintRange>(sym, R) : NULL;\
}
AssumeX(EQ)
AssumeX(NE)
AssumeX(LT)
AssumeX(GT)
AssumeX(LE)
AssumeX(GE)
//===------------------------------------------------------------------------===
// Pretty-printing.
//===------------------------------------------------------------------------===/
void RangeConstraintManager::print(const GRState* St, llvm::raw_ostream& Out,
const char* nl, const char *sep) {
ConstraintRangeTy Ranges = St->get<ConstraintRange>();
if (Ranges.isEmpty())
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);
}
}