1 files changed, 236 insertions, 0 deletions
diff --git a/lib/EntoSA/Environment.cpp b/lib/EntoSA/Environment.cpp
new file mode 100644
index 0000000000..eecbabbb2e
--- /dev/null
+++ b/lib/EntoSA/Environment.cpp
@@ -0,0 +1,236 @@
+//== Environment.cpp - Map from Stmt* to Locations/Values -------*- C++ -*--==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defined the Environment and EnvironmentManager classes.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Analysis/AnalysisContext.h"
+#include "clang/Analysis/CFG.h"
+#include "clang/EntoSA/PathSensitive/GRState.h"
+
+using namespace clang;
+using namespace ento;
+
+SVal Environment::lookupExpr(const Stmt* E) const {
+  const SVal* X = ExprBindings.lookup(E);
+  if (X) {
+    SVal V = *X;
+    return V;
+  }
+  return UnknownVal();
+}
+
+SVal Environment::getSVal(const Stmt *E, SValBuilder& svalBuilder) const {
+  for (;;) {
+    switch (E->getStmtClass()) {
+      case Stmt::AddrLabelExprClass:
+        return svalBuilder.makeLoc(cast<AddrLabelExpr>(E));
+      case Stmt::ParenExprClass:
+        // ParenExprs are no-ops.
+        E = cast<ParenExpr>(E)->getSubExpr();
+        continue;
+      case Stmt::CharacterLiteralClass: {
+        const CharacterLiteral* C = cast<CharacterLiteral>(E);
+        return svalBuilder.makeIntVal(C->getValue(), C->getType());
+      }
+      case Stmt::CXXBoolLiteralExprClass: {
+        const SVal *X = ExprBindings.lookup(E);
+        if (X) 
+          return *X;
+        else 
+          return svalBuilder.makeIntVal(cast<CXXBoolLiteralExpr>(E));
+      }
+      case Stmt::IntegerLiteralClass: {
+        // In C++, this expression may have been bound to a temporary object.
+        SVal const *X = ExprBindings.lookup(E);
+        if (X)
+          return *X;
+        else
+          return svalBuilder.makeIntVal(cast<IntegerLiteral>(E));
+      }
+      case Stmt::ImplicitCastExprClass:
+      case Stmt::CStyleCastExprClass: {
+        // We blast through no-op casts to get the descendant
+        // subexpression that has a value.
+        const CastExpr* C = cast<CastExpr>(E);
+        QualType CT = C->getType();
+        if (CT->isVoidType())
+          return UnknownVal();
+        if (C->getCastKind() == CK_NoOp) {
+          E = C->getSubExpr();
+          continue;
+        }
+        break;
+      }
+      case Stmt::ExprWithCleanupsClass:
+        E = cast<ExprWithCleanups>(E)->getSubExpr();
+        continue;
+      case Stmt::CXXBindTemporaryExprClass:
+        E = cast<CXXBindTemporaryExpr>(E)->getSubExpr();
+        continue;
+      case Stmt::CXXFunctionalCastExprClass:
+        E = cast<CXXFunctionalCastExpr>(E)->getSubExpr();
+        continue;        
+      // Handle all other Stmt* using a lookup.
+      default:
+        break;
+    };
+    break;
+  }
+  return lookupExpr(E);
+}
+
+Environment EnvironmentManager::bindExpr(Environment Env, const Stmt *S,
+                                         SVal V, bool Invalidate) {
+  assert(S);
+
+  if (V.isUnknown()) {
+    if (Invalidate)
+      return Environment(F.remove(Env.ExprBindings, S));
+    else
+      return Env;
+  }
+
+  return Environment(F.add(Env.ExprBindings, S, V));
+}
+
+static inline const Stmt *MakeLocation(const Stmt *S) {
+  return (const Stmt*) (((uintptr_t) S) | 0x1);
+}
+
+Environment EnvironmentManager::bindExprAndLocation(Environment Env,
+                                                    const Stmt *S,
+                                                    SVal location, SVal V) {
+  return Environment(F.add(F.add(Env.ExprBindings, MakeLocation(S), location),
+                           S, V));
+}
+
+namespace {
+class MarkLiveCallback : public SymbolVisitor {
+  SymbolReaper &SymReaper;
+public:
+  MarkLiveCallback(SymbolReaper &symreaper) : SymReaper(symreaper) {}
+  bool VisitSymbol(SymbolRef sym) { SymReaper.markLive(sym); return true; }
+};
+} // end anonymous namespace
+
+static bool isBlockExprInCallers(const Stmt *E, const LocationContext *LC) {
+  const LocationContext *ParentLC = LC->getParent();
+  while (ParentLC) {
+    CFG &C = *ParentLC->getCFG();
+    if (C.isBlkExpr(E))
+      return true;
+    ParentLC = ParentLC->getParent();
+  }
+
+  return false;
+}
+
+// In addition to mapping from Stmt * - > SVals in the Environment, we also
+// maintain a mapping from Stmt * -> SVals (locations) that were used during
+// a load and store.
+static inline bool IsLocation(const Stmt *S) {
+  return (bool) (((uintptr_t) S) & 0x1);
+}
+
+// RemoveDeadBindings:
+//  - Remove subexpression bindings.
+//  - Remove dead block expression bindings.
+//  - Keep live block expression bindings:
+//   - Mark their reachable symbols live in SymbolReaper,
+//     see ScanReachableSymbols.
+//   - Mark the region in DRoots if the binding is a loc::MemRegionVal.
+Environment
+EnvironmentManager::RemoveDeadBindings(Environment Env,
+                                       SymbolReaper &SymReaper,
+                                       const GRState *ST,
+                              llvm::SmallVectorImpl<const MemRegion*> &DRoots) {
+
+  CFG &C = *SymReaper.getLocationContext()->getCFG();
+
+  // We construct a new Environment object entirely, as this is cheaper than
+  // individually removing all the subexpression bindings (which will greatly
+  // outnumber block-level expression bindings).
+  Environment NewEnv = getInitialEnvironment();
+  
+  llvm::SmallVector<std::pair<const Stmt*, SVal>, 10> deferredLocations;
+
+  // Iterate over the block-expr bindings.
+  for (Environment::iterator I = Env.begin(), E = Env.end();
+       I != E; ++I) {
+
+    const Stmt *BlkExpr = I.getKey();
+    
+    // For recorded locations (used when evaluating loads and stores), we
+    // consider them live only when their associated normal expression is
+    // also live.
+    // NOTE: This assumes that loads/stores that evaluated to UnknownVal
+    // still have an entry in the map.
+    if (IsLocation(BlkExpr)) {
+      deferredLocations.push_back(std::make_pair(BlkExpr, I.getData()));
+      continue;
+    }
+    
+    const SVal &X = I.getData();
+
+    // Block-level expressions in callers are assumed always live.
+    if (isBlockExprInCallers(BlkExpr, SymReaper.getLocationContext())) {
+      NewEnv.ExprBindings = F.add(NewEnv.ExprBindings, BlkExpr, X);
+
+      if (isa<loc::MemRegionVal>(X)) {
+        const MemRegion* R = cast<loc::MemRegionVal>(X).getRegion();
+        DRoots.push_back(R);
+      }
+
+      // Mark all symbols in the block expr's value live.
+      MarkLiveCallback cb(SymReaper);
+      ST->scanReachableSymbols(X, cb);
+      continue;
+    }
+
+    // Not a block-level expression?
+    if (!C.isBlkExpr(BlkExpr))
+      continue;
+
+    if (SymReaper.isLive(BlkExpr)) {
+      // Copy the binding to the new map.
+      NewEnv.ExprBindings = F.add(NewEnv.ExprBindings, BlkExpr, X);
+
+      // If the block expr's value is a memory region, then mark that region.
+      if (isa<loc::MemRegionVal>(X)) {
+        const MemRegion* R = cast<loc::MemRegionVal>(X).getRegion();
+        DRoots.push_back(R);
+      }
+
+      // Mark all symbols in the block expr's value live.
+      MarkLiveCallback cb(SymReaper);
+      ST->scanReachableSymbols(X, cb);
+      continue;
+    }
+
+    // Otherwise the expression is dead with a couple exceptions.
+    // Do not misclean LogicalExpr or ConditionalOperator.  It is dead at the
+    // beginning of itself, but we need its UndefinedVal to determine its
+    // SVal.
+    if (X.isUndef() && cast<UndefinedVal>(X).getData())
+      NewEnv.ExprBindings = F.add(NewEnv.ExprBindings, BlkExpr, X);
+  }
+  
+  // Go through he deferred locations and add them to the new environment if
+  // the correspond Stmt* is in the map as well.
+  for (llvm::SmallVectorImpl<std::pair<const Stmt*, SVal> >::iterator
+      I = deferredLocations.begin(), E = deferredLocations.end(); I != E; ++I) {
+    const Stmt *S = (Stmt*) (((uintptr_t) I->first) & (uintptr_t) ~0x1);
+    if (NewEnv.ExprBindings.lookup(S))
+      NewEnv.ExprBindings = F.add(NewEnv.ExprBindings, I->first, I->second);
+  }
+
+  return NewEnv;
+}