lib/Analysis/MemRegion.cpp

//== MemRegion.cpp - Abstract memory regions for static analysis --*- 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 MemRegion and its subclasses.  MemRegion defines a
//  partially-typed abstraction of memory useful for path-sensitive dataflow
//  analyses.
//
//===----------------------------------------------------------------------===//

#include "llvm/Support/raw_ostream.h"
#include "clang/Analysis/PathSensitive/MemRegion.h"

using namespace clang;

//===----------------------------------------------------------------------===//
// Basic methods.
//===----------------------------------------------------------------------===//

MemRegion::~MemRegion() {}

bool SubRegion::isSubRegionOf(const MemRegion* R) const {
  const MemRegion* r = getSuperRegion();
  while (r != 0) {
    if (r == R)
      return true;
    if (const SubRegion* sr = dyn_cast<SubRegion>(r))
      r = sr->getSuperRegion();
    else
      break;
  }
  return false;
}

void MemSpaceRegion::Profile(llvm::FoldingSetNodeID& ID) const {
  ID.AddInteger((unsigned)getKind());
}

void StringRegion::ProfileRegion(llvm::FoldingSetNodeID& ID, 
                                 const StringLiteral* Str, 
                                 const MemRegion* superRegion) {
  ID.AddInteger((unsigned) StringRegionKind);
  ID.AddPointer(Str);
  ID.AddPointer(superRegion);
}

void AllocaRegion::ProfileRegion(llvm::FoldingSetNodeID& ID,
                                 const Expr* Ex, unsigned cnt) {
  ID.AddInteger((unsigned) AllocaRegionKind);
  ID.AddPointer(Ex);
  ID.AddInteger(cnt);
}

void AllocaRegion::Profile(llvm::FoldingSetNodeID& ID) const {
  ProfileRegion(ID, Ex, Cnt);
}

void TypedViewRegion::ProfileRegion(llvm::FoldingSetNodeID& ID, QualType T, 
                                    const MemRegion* superRegion) {
  ID.AddInteger((unsigned) TypedViewRegionKind);
  ID.Add(T);
  ID.AddPointer(superRegion);
}

void CompoundLiteralRegion::Profile(llvm::FoldingSetNodeID& ID) const {
  CompoundLiteralRegion::ProfileRegion(ID, CL, superRegion);
}

void CompoundLiteralRegion::ProfileRegion(llvm::FoldingSetNodeID& ID,
                                          const CompoundLiteralExpr* CL,
                                          const MemRegion* superRegion) {
  ID.AddInteger((unsigned) CompoundLiteralRegionKind);
  ID.AddPointer(CL);
  ID.AddPointer(superRegion);
}

void DeclRegion::ProfileRegion(llvm::FoldingSetNodeID& ID, const Decl* D,
                               const MemRegion* superRegion, Kind k) {
  ID.AddInteger((unsigned) k);
  ID.AddPointer(D);
  ID.AddPointer(superRegion);
}

void DeclRegion::Profile(llvm::FoldingSetNodeID& ID) const {
  DeclRegion::ProfileRegion(ID, D, superRegion, getKind());
}

void SymbolicRegion::ProfileRegion(llvm::FoldingSetNodeID& ID, SymbolRef sym,
                                   const MemRegion *sreg) {
  ID.AddInteger((unsigned) MemRegion::SymbolicRegionKind);
  ID.Add(sym);
  ID.AddPointer(sreg);
}

void SymbolicRegion::Profile(llvm::FoldingSetNodeID& ID) const {
  SymbolicRegion::ProfileRegion(ID, sym, getSuperRegion());
}

void ElementRegion::ProfileRegion(llvm::FoldingSetNodeID& ID,
                                  QualType ElementType, SVal Idx, 
                                  const MemRegion* superRegion) {
  ID.AddInteger(MemRegion::ElementRegionKind);
  ID.Add(ElementType);
  ID.AddPointer(superRegion);
  Idx.Profile(ID);
}

void ElementRegion::Profile(llvm::FoldingSetNodeID& ID) const {
  ElementRegion::ProfileRegion(ID, ElementType, Index, superRegion);
}

void CodeTextRegion::ProfileRegion(llvm::FoldingSetNodeID& ID, const void* data,
                                   QualType t) {
  ID.AddInteger(MemRegion::CodeTextRegionKind);
  ID.AddPointer(data);
  ID.Add(t);
}

void CodeTextRegion::Profile(llvm::FoldingSetNodeID& ID) const {
  CodeTextRegion::ProfileRegion(ID, Data, LocationType);
}

//===----------------------------------------------------------------------===//
// Region pretty-printing.
//===----------------------------------------------------------------------===//

std::string MemRegion::getString() const {
  std::string s;
  llvm::raw_string_ostream os(s);
  print(os);
  return os.str();
}

void MemRegion::print(llvm::raw_ostream& os) const {
  os << "<Unknown Region>";
}

void AllocaRegion::print(llvm::raw_ostream& os) const {
  os << "alloca{" << (void*) Ex << ',' << Cnt << '}';
}

void CodeTextRegion::print(llvm::raw_ostream& os) const {
  os << "code{";
  if (isDeclared())
    os << getDecl()->getDeclName().getAsString();
  else
    os << '$' << getSymbol();

  os << '}';
}

void CompoundLiteralRegion::print(llvm::raw_ostream& os) const {
  // FIXME: More elaborate pretty-printing.
  os << "{ " << (void*) CL <<  " }";
}

void ElementRegion::print(llvm::raw_ostream& os) const {
  superRegion->print(os);
  os << '['; Index.print(os); os << ']';
}

void FieldRegion::print(llvm::raw_ostream& os) const {
  superRegion->print(os);
  os << "->" << getDecl()->getNameAsString();
}

void StringRegion::print(llvm::raw_ostream& os) const {
  Str->printPretty(os);
}

void SymbolicRegion::print(llvm::raw_ostream& os) const {
  os << "SymRegion-" << sym;
}

void TypedViewRegion::print(llvm::raw_ostream& os) const {
  os << "typed_view{" << LValueType.getAsString() << ',';
  getSuperRegion()->print(os);
  os << '}';
}

void VarRegion::print(llvm::raw_ostream& os) const {
  os << cast<VarDecl>(D)->getNameAsString();
}

//===----------------------------------------------------------------------===//
// MemRegionManager methods.
//===----------------------------------------------------------------------===//
  
MemSpaceRegion* MemRegionManager::LazyAllocate(MemSpaceRegion*& region) {
  
  if (!region) {  
    region = (MemSpaceRegion*) A.Allocate<MemSpaceRegion>();
    new (region) MemSpaceRegion();
  }
  
  return region;
}

MemSpaceRegion* MemRegionManager::getStackRegion() {
  return LazyAllocate(stack);
}

MemSpaceRegion* MemRegionManager::getGlobalsRegion() {
  return LazyAllocate(globals);
}

MemSpaceRegion* MemRegionManager::getHeapRegion() {
  return LazyAllocate(heap);
}

MemSpaceRegion* MemRegionManager::getUnknownRegion() {
  return LazyAllocate(unknown);
}

MemSpaceRegion* MemRegionManager::getCodeRegion() {
  return LazyAllocate(code);
}

bool MemRegionManager::onStack(const MemRegion* R) {
  while (const SubRegion* SR = dyn_cast<SubRegion>(R))
    R = SR->getSuperRegion();

  return (R != 0) && (R == stack);
}

bool MemRegionManager::onHeap(const MemRegion* R) {
  while (const SubRegion* SR = dyn_cast<SubRegion>(R))
    R = SR->getSuperRegion();

  return (R != 0) && (R == heap); 
}

//===----------------------------------------------------------------------===//
// Constructing regions.
//===----------------------------------------------------------------------===//

StringRegion* MemRegionManager::getStringRegion(const StringLiteral* Str) {
  return getRegion<StringRegion>(Str);
}

VarRegion* MemRegionManager::getVarRegion(const VarDecl* d) {
  return getRegion<VarRegion>(d);
}

CompoundLiteralRegion*
MemRegionManager::getCompoundLiteralRegion(const CompoundLiteralExpr* CL) {
  return getRegion<CompoundLiteralRegion>(CL);
}

ElementRegion*
MemRegionManager::getElementRegion(QualType elementType, SVal Idx,
                                 const MemRegion* superRegion, ASTContext& Ctx){

  QualType T = Ctx.getCanonicalType(elementType);

  llvm::FoldingSetNodeID ID;
  ElementRegion::ProfileRegion(ID, T, Idx, superRegion);

  void* InsertPos;
  MemRegion* data = Regions.FindNodeOrInsertPos(ID, InsertPos);
  ElementRegion* R = cast_or_null<ElementRegion>(data);

  if (!R) {
    R = (ElementRegion*) A.Allocate<ElementRegion>();
    new (R) ElementRegion(T, Idx, superRegion);
    Regions.InsertNode(R, InsertPos);
  }

  return R;
}

CodeTextRegion* MemRegionManager::getCodeTextRegion(const FunctionDecl* fd,
                                                    QualType t) {
  llvm::FoldingSetNodeID ID;
  CodeTextRegion::ProfileRegion(ID, fd, t);
  void* InsertPos;
  MemRegion* data = Regions.FindNodeOrInsertPos(ID, InsertPos);
  CodeTextRegion* R = cast_or_null<CodeTextRegion>(data);

  if (!R) {
    R = (CodeTextRegion*) A.Allocate<CodeTextRegion>();
    new (R) CodeTextRegion(fd, t, getCodeRegion());
    Regions.InsertNode(R, InsertPos);
  }

  return R;
}

CodeTextRegion* MemRegionManager::getCodeTextRegion(SymbolRef sym, QualType t) {
  llvm::FoldingSetNodeID ID;
  CodeTextRegion::ProfileRegion(ID, sym, t);
  void* InsertPos;
  MemRegion* data = Regions.FindNodeOrInsertPos(ID, InsertPos);
  CodeTextRegion* R = cast_or_null<CodeTextRegion>(data);

  if (!R) {
    R = (CodeTextRegion*) A.Allocate<CodeTextRegion>();
    new (R) CodeTextRegion(sym, t, getCodeRegion());
    Regions.InsertNode(R, InsertPos);
  }

  return R;
}

/// getSymbolicRegion - Retrieve or create a "symbolic" memory region.
SymbolicRegion* MemRegionManager::getSymbolicRegion(SymbolRef sym) {
  return getRegion<SymbolicRegion>(sym);
}

FieldRegion* MemRegionManager::getFieldRegion(const FieldDecl* d,
                                              const MemRegion* superRegion) {
  return getRegion<FieldRegion>(d, superRegion);
}

ObjCIvarRegion*
MemRegionManager::getObjCIvarRegion(const ObjCIvarDecl* d,
                                    const MemRegion* superRegion) {
  return getRegion<ObjCIvarRegion>(d, superRegion);
}

ObjCObjectRegion*
MemRegionManager::getObjCObjectRegion(const ObjCInterfaceDecl* d,
                                      const MemRegion* superRegion) {
  return getRegion<ObjCObjectRegion>(d, superRegion);
}

TypedViewRegion* 
MemRegionManager::getTypedViewRegion(QualType t, const MemRegion* superRegion) {
  return getRegion<TypedViewRegion>(t, superRegion);
}

AllocaRegion* MemRegionManager::getAllocaRegion(const Expr* E, unsigned cnt) {
  llvm::FoldingSetNodeID ID;
  AllocaRegion::ProfileRegion(ID, E, cnt);
  
  void* InsertPos;
  MemRegion* data = Regions.FindNodeOrInsertPos(ID, InsertPos);
  AllocaRegion* R = cast_or_null<AllocaRegion>(data);
  
  if (!R) {
    R = (AllocaRegion*) A.Allocate<AllocaRegion>();
    new (R) AllocaRegion(E, cnt, getStackRegion());
    Regions.InsertNode(R, InsertPos);
  }
  
  return R;
}

bool MemRegionManager::hasStackStorage(const MemRegion* R) {

  // Only subregions can have stack storage.
  const SubRegion* SR = dyn_cast<SubRegion>(R);

  if (!SR)
    return false;

  MemSpaceRegion* S = getStackRegion();
  
  while (SR) {
    R = SR->getSuperRegion();
    if (R == S)
      return true;
    
    SR = dyn_cast<SubRegion>(R);    
  }

  return false;
}


//===----------------------------------------------------------------------===//
// View handling.
//===----------------------------------------------------------------------===//

const MemRegion *TypedViewRegion::removeViews() const {
  const SubRegion *SR = this;
  const MemRegion *R = SR;
  while (SR && isa<TypedViewRegion>(SR)) {
    R = SR->getSuperRegion();
    SR = dyn_cast<SubRegion>(R);
  }
  return R;
}