lib/StaticAnalyzer/SymbolManager.cpp

   1 //== SymbolManager.h - Management of Symbolic Values ------------*- 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 SymbolManager, a class that manages symbolic values
  11 //  created for use by ExprEngine and related classes.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "clang/StaticAnalyzer/PathSensitive/SymbolManager.h"
  16 #include "clang/Analysis/Analyses/LiveVariables.h"
  17 #include "clang/StaticAnalyzer/PathSensitive/MemRegion.h"
  18 #include "llvm/Support/raw_ostream.h"
  19
  20 using namespace clang;
  21 using namespace ento;
  22
  23 void SymExpr::dump() const {
  24   dumpToStream(llvm::errs());
  25 }
  26
  27 static void print(llvm::raw_ostream& os, BinaryOperator::Opcode Op) {
  28   switch (Op) {
  29     default:
  30       assert(false && "operator printing not implemented");
  31       break;
  32     case BO_Mul: os << '*'  ; break;
  33     case BO_Div: os << '/'  ; break;
  34     case BO_Rem: os << '%'  ; break;
  35     case BO_Add: os << '+'  ; break;
  36     case BO_Sub: os << '-'  ; break;
  37     case BO_Shl: os << "<<" ; break;
  38     case BO_Shr: os << ">>" ; break;
  39     case BO_LT:  os << "<"  ; break;
  40     case BO_GT:  os << '>'  ; break;
  41     case BO_LE:  os << "<=" ; break;
  42     case BO_GE:  os << ">=" ; break;
  43     case BO_EQ:  os << "==" ; break;
  44     case BO_NE:  os << "!=" ; break;
  45     case BO_And: os << '&'  ; break;
  46     case BO_Xor: os << '^'  ; break;
  47     case BO_Or:  os << '|'  ; break;
  48   }
  49 }
  50
  51 void SymIntExpr::dumpToStream(llvm::raw_ostream& os) const {
  52   os << '(';
  53   getLHS()->dumpToStream(os);
  54   os << ") ";
  55   print(os, getOpcode());
  56   os << ' ' << getRHS().getZExtValue();
  57   if (getRHS().isUnsigned()) os << 'U';
  58 }
  59
  60 void SymSymExpr::dumpToStream(llvm::raw_ostream& os) const {
  61   os << '(';
  62   getLHS()->dumpToStream(os);
  63   os << ") ";
  64   os << '(';
  65   getRHS()->dumpToStream(os);
  66   os << ')';
  67 }
  68
  69 void SymbolConjured::dumpToStream(llvm::raw_ostream& os) const {
  70   os << "conj_$" << getSymbolID() << '{' << T.getAsString() << '}';
  71 }
  72
  73 void SymbolDerived::dumpToStream(llvm::raw_ostream& os) const {
  74   os << "derived_$" << getSymbolID() << '{'
  75      << getParentSymbol() << ',' << getRegion() << '}';
  76 }
  77
  78 void SymbolExtent::dumpToStream(llvm::raw_ostream& os) const {
  79   os << "extent_$" << getSymbolID() << '{' << getRegion() << '}';
  80 }
  81
  82 void SymbolMetadata::dumpToStream(llvm::raw_ostream& os) const {
  83   os << "meta_$" << getSymbolID() << '{'
  84      << getRegion() << ',' << T.getAsString() << '}';
  85 }
  86
  87 void SymbolRegionValue::dumpToStream(llvm::raw_ostream& os) const {
  88   os << "reg_$" << getSymbolID() << "<" << R << ">";
  89 }
  90
  91 const SymbolRegionValue*
  92 SymbolManager::getRegionValueSymbol(const TypedRegion* R) {
  93   llvm::FoldingSetNodeID profile;
  94   SymbolRegionValue::Profile(profile, R);
  95   void* InsertPos;
  96   SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
  97   if (!SD) {
  98     SD = (SymExpr*) BPAlloc.Allocate<SymbolRegionValue>();
  99     new (SD) SymbolRegionValue(SymbolCounter, R);
 100     DataSet.InsertNode(SD, InsertPos);
 101     ++SymbolCounter;
 102   }
 103
 104   return cast<SymbolRegionValue>(SD);
 105 }
 106
 107 const SymbolConjured*
 108 SymbolManager::getConjuredSymbol(const Stmt* E, QualType T, unsigned Count,
 109                                  const void* SymbolTag) {
 110
 111   llvm::FoldingSetNodeID profile;
 112   SymbolConjured::Profile(profile, E, T, Count, SymbolTag);
 113   void* InsertPos;
 114   SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
 115   if (!SD) {
 116     SD = (SymExpr*) BPAlloc.Allocate<SymbolConjured>();
 117     new (SD) SymbolConjured(SymbolCounter, E, T, Count, SymbolTag);
 118     DataSet.InsertNode(SD, InsertPos);
 119     ++SymbolCounter;
 120   }
 121
 122   return cast<SymbolConjured>(SD);
 123 }
 124
 125 const SymbolDerived*
 126 SymbolManager::getDerivedSymbol(SymbolRef parentSymbol,
 127                                 const TypedRegion *R) {
 128
 129   llvm::FoldingSetNodeID profile;
 130   SymbolDerived::Profile(profile, parentSymbol, R);
 131   void* InsertPos;
 132   SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
 133   if (!SD) {
 134     SD = (SymExpr*) BPAlloc.Allocate<SymbolDerived>();
 135     new (SD) SymbolDerived(SymbolCounter, parentSymbol, R);
 136     DataSet.InsertNode(SD, InsertPos);
 137     ++SymbolCounter;
 138   }
 139
 140   return cast<SymbolDerived>(SD);
 141 }
 142
 143 const SymbolExtent*
 144 SymbolManager::getExtentSymbol(const SubRegion *R) {
 145   llvm::FoldingSetNodeID profile;
 146   SymbolExtent::Profile(profile, R);
 147   void* InsertPos;
 148   SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
 149   if (!SD) {
 150     SD = (SymExpr*) BPAlloc.Allocate<SymbolExtent>();
 151     new (SD) SymbolExtent(SymbolCounter, R);
 152     DataSet.InsertNode(SD, InsertPos);
 153     ++SymbolCounter;
 154   }
 155
 156   return cast<SymbolExtent>(SD);
 157 }
 158
 159 const SymbolMetadata*
 160 SymbolManager::getMetadataSymbol(const MemRegion* R, const Stmt* S, QualType T,
 161                                  unsigned Count, const void* SymbolTag) {
 162
 163   llvm::FoldingSetNodeID profile;
 164   SymbolMetadata::Profile(profile, R, S, T, Count, SymbolTag);
 165   void* InsertPos;
 166   SymExpr *SD = DataSet.FindNodeOrInsertPos(profile, InsertPos);
 167   if (!SD) {
 168     SD = (SymExpr*) BPAlloc.Allocate<SymbolMetadata>();
 169     new (SD) SymbolMetadata(SymbolCounter, R, S, T, Count, SymbolTag);
 170     DataSet.InsertNode(SD, InsertPos);
 171     ++SymbolCounter;
 172   }
 173
 174   return cast<SymbolMetadata>(SD);
 175 }
 176
 177 const SymIntExpr *SymbolManager::getSymIntExpr(const SymExpr *lhs,
 178                                                BinaryOperator::Opcode op,
 179                                                const llvm::APSInt& v,
 180                                                QualType t) {
 181   llvm::FoldingSetNodeID ID;
 182   SymIntExpr::Profile(ID, lhs, op, v, t);
 183   void *InsertPos;
 184   SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
 185
 186   if (!data) {
 187     data = (SymIntExpr*) BPAlloc.Allocate<SymIntExpr>();
 188     new (data) SymIntExpr(lhs, op, v, t);
 189     DataSet.InsertNode(data, InsertPos);
 190   }
 191
 192   return cast<SymIntExpr>(data);
 193 }
 194
 195 const SymSymExpr *SymbolManager::getSymSymExpr(const SymExpr *lhs,
 196                                                BinaryOperator::Opcode op,
 197                                                const SymExpr *rhs,
 198                                                QualType t) {
 199   llvm::FoldingSetNodeID ID;
 200   SymSymExpr::Profile(ID, lhs, op, rhs, t);
 201   void *InsertPos;
 202   SymExpr *data = DataSet.FindNodeOrInsertPos(ID, InsertPos);
 203
 204   if (!data) {
 205     data = (SymSymExpr*) BPAlloc.Allocate<SymSymExpr>();
 206     new (data) SymSymExpr(lhs, op, rhs, t);
 207     DataSet.InsertNode(data, InsertPos);
 208   }
 209
 210   return cast<SymSymExpr>(data);
 211 }
 212
 213 QualType SymbolConjured::getType(ASTContext&) const {
 214   return T;
 215 }
 216
 217 QualType SymbolDerived::getType(ASTContext& Ctx) const {
 218   return R->getValueType();
 219 }
 220
 221 QualType SymbolExtent::getType(ASTContext& Ctx) const {
 222   return Ctx.getSizeType();
 223 }
 224
 225 QualType SymbolMetadata::getType(ASTContext&) const {
 226   return T;
 227 }
 228
 229 QualType SymbolRegionValue::getType(ASTContext& C) const {
 230   return R->getValueType();
 231 }
 232
 233 SymbolManager::~SymbolManager() {}
 234
 235 bool SymbolManager::canSymbolicate(QualType T) {
 236   if (Loc::IsLocType(T))
 237     return true;
 238
 239   if (T->isIntegerType())
 240     return T->isScalarType();
 241
 242   if (T->isRecordType())
 243     return true;
 244
 245   return false;
 246 }
 247
 248 void SymbolReaper::markLive(SymbolRef sym) {
 249   TheLiving.insert(sym);
 250   TheDead.erase(sym);
 251 }
 252
 253 void SymbolReaper::markInUse(SymbolRef sym) {
 254   if (isa<SymbolMetadata>(sym))
 255     MetadataInUse.insert(sym);
 256 }
 257
 258 bool SymbolReaper::maybeDead(SymbolRef sym) {
 259   if (isLive(sym))
 260     return false;
 261
 262   TheDead.insert(sym);
 263   return true;
 264 }
 265
 266 static bool IsLiveRegion(SymbolReaper &Reaper, const MemRegion *MR) {
 267   MR = MR->getBaseRegion();
 268
 269   if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(MR))
 270     return Reaper.isLive(SR->getSymbol());
 271
 272   if (const VarRegion *VR = dyn_cast<VarRegion>(MR))
 273     return Reaper.isLive(VR);
 274
 275   // FIXME: This is a gross over-approximation. What we really need is a way to
 276   // tell if anything still refers to this region. Unlike SymbolicRegions,
 277   // AllocaRegions don't have associated symbols, though, so we don't actually
 278   // have a way to track their liveness.
 279   if (isa<AllocaRegion>(MR))
 280     return true;
 281
 282   if (isa<CXXThisRegion>(MR))
 283     return true;
 284
 285   if (isa<MemSpaceRegion>(MR))
 286     return true;
 287
 288   return false;
 289 }
 290
 291 bool SymbolReaper::isLive(SymbolRef sym) {
 292   if (TheLiving.count(sym))
 293     return true;
 294
 295   if (const SymbolDerived *derived = dyn_cast<SymbolDerived>(sym)) {
 296     if (isLive(derived->getParentSymbol())) {
 297       markLive(sym);
 298       return true;
 299     }
 300     return false;
 301   }
 302
 303   if (const SymbolExtent *extent = dyn_cast<SymbolExtent>(sym)) {
 304     if (IsLiveRegion(*this, extent->getRegion())) {
 305       markLive(sym);
 306       return true;
 307     }
 308     return false;
 309   }
 310
 311   if (const SymbolMetadata *metadata = dyn_cast<SymbolMetadata>(sym)) {
 312     if (MetadataInUse.count(sym)) {
 313       if (IsLiveRegion(*this, metadata->getRegion())) {
 314         markLive(sym);
 315         MetadataInUse.erase(sym);
 316         return true;
 317       }
 318     }
 319     return false;
 320   }
 321
 322   // Interogate the symbol.  It may derive from an input value to
 323   // the analyzed function/method.
 324   return isa<SymbolRegionValue>(sym);
 325 }
 326
 327 bool SymbolReaper::isLive(const Stmt* ExprVal) const {
 328   return LCtx->getAnalysisContext()->getRelaxedLiveVariables()->
 329       isLive(Loc, ExprVal);
 330 }
 331
 332 bool SymbolReaper::isLive(const VarRegion *VR) const {
 333   const StackFrameContext *VarContext = VR->getStackFrame();
 334   const StackFrameContext *CurrentContext = LCtx->getCurrentStackFrame();
 335
 336   if (VarContext == CurrentContext)
 337     return LCtx->getAnalysisContext()->getRelaxedLiveVariables()->
 338         isLive(Loc, VR->getDecl());
 339
 340   return VarContext->isParentOf(CurrentContext);
 341 }
 342
 343 SymbolVisitor::~SymbolVisitor() {}