Add the clang library to the repo (with some of my changes, too).

1 files changed, 725 insertions, 0 deletions

diff --git a/clang/lib/Analysis/UninitializedValues.cpp b/clang/lib/Analysis/UninitializedValues.cpp
new file mode 100644
index 0000000..1c7e6b6
--- /dev/null
+++ b/clang/lib/Analysis/UninitializedValues.cpp
@@ -0,0 +1,725 @@
+//==- UninitializedValues.cpp - Find Uninitialized 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 implements uninitialized values analysis for source-level CFGs.
+//
+//===----------------------------------------------------------------------===//
+
+#include <utility>
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/PackedVector.h"
+#include "llvm/ADT/DenseMap.h"
+#include "clang/AST/Decl.h"
+#include "clang/Analysis/CFG.h"
+#include "clang/Analysis/AnalysisContext.h"
+#include "clang/Analysis/Visitors/CFGRecStmtDeclVisitor.h"
+#include "clang/Analysis/Analyses/UninitializedValues.h"
+#include "llvm/Support/SaveAndRestore.h"
+
+using namespace clang;
+
+static bool isTrackedVar(const VarDecl *vd, const DeclContext *dc) {
+  if (vd->isLocalVarDecl() && !vd->hasGlobalStorage() &&
+      !vd->isExceptionVariable() &&
+      vd->getDeclContext() == dc) {
+    QualType ty = vd->getType();
+    return ty->isScalarType() || ty->isVectorType();
+  }
+  return false;
+}
+
+//------------------------------------------------------------------------====//
+// DeclToIndex: a mapping from Decls we track to value indices.
+//====------------------------------------------------------------------------//
+
+namespace {
+class DeclToIndex {
+  llvm::DenseMap<const VarDecl *, unsigned> map;
+public:
+  DeclToIndex() {}
+  
+  /// Compute the actual mapping from declarations to bits.
+  void computeMap(const DeclContext &dc);
+  
+  /// Return the number of declarations in the map.
+  unsigned size() const { return map.size(); }
+  
+  /// Returns the bit vector index for a given declaration.
+  llvm::Optional<unsigned> getValueIndex(const VarDecl *d) const;
+};
+}
+
+void DeclToIndex::computeMap(const DeclContext &dc) {
+  unsigned count = 0;
+  DeclContext::specific_decl_iterator<VarDecl> I(dc.decls_begin()),
+                                               E(dc.decls_end());
+  for ( ; I != E; ++I) {
+    const VarDecl *vd = *I;
+    if (isTrackedVar(vd, &dc))
+      map[vd] = count++;
+  }
+}
+
+llvm::Optional<unsigned> DeclToIndex::getValueIndex(const VarDecl *d) const {
+  llvm::DenseMap<const VarDecl *, unsigned>::const_iterator I = map.find(d);
+  if (I == map.end())
+    return llvm::Optional<unsigned>();
+  return I->second;
+}
+
+//------------------------------------------------------------------------====//
+// CFGBlockValues: dataflow values for CFG blocks.
+//====------------------------------------------------------------------------//
+
+// These values are defined in such a way that a merge can be done using
+// a bitwise OR.
+enum Value { Unknown = 0x0,         /* 00 */
+             Initialized = 0x1,     /* 01 */
+             Uninitialized = 0x2,   /* 10 */
+             MayUninitialized = 0x3 /* 11 */ };
+
+static bool isUninitialized(const Value v) {
+  return v >= Uninitialized;
+}
+static bool isAlwaysUninit(const Value v) {
+  return v == Uninitialized;
+}
+
+namespace {
+
+typedef llvm::PackedVector<Value, 2> ValueVector;
+typedef std::pair<ValueVector *, ValueVector *> BVPair;
+
+class CFGBlockValues {
+  const CFG &cfg;
+  BVPair *vals;
+  ValueVector scratch;
+  DeclToIndex declToIndex;
+  
+  ValueVector &lazyCreate(ValueVector *&bv);
+public:
+  CFGBlockValues(const CFG &cfg);
+  ~CFGBlockValues();
+  
+  unsigned getNumEntries() const { return declToIndex.size(); }
+  
+  void computeSetOfDeclarations(const DeclContext &dc);  
+  ValueVector &getValueVector(const CFGBlock *block,
+                                const CFGBlock *dstBlock);
+
+  BVPair &getValueVectors(const CFGBlock *block, bool shouldLazyCreate);
+
+  void mergeIntoScratch(ValueVector const &source, bool isFirst);
+  bool updateValueVectorWithScratch(const CFGBlock *block);
+  bool updateValueVectors(const CFGBlock *block, const BVPair &newVals);
+  
+  bool hasNoDeclarations() const {
+    return declToIndex.size() == 0;
+  }
+
+  void resetScratch();
+  ValueVector &getScratch() { return scratch; }
+  
+  ValueVector::reference operator[](const VarDecl *vd);
+};  
+} // end anonymous namespace
+
+CFGBlockValues::CFGBlockValues(const CFG &c) : cfg(c), vals(0) {
+  unsigned n = cfg.getNumBlockIDs();
+  if (!n)
+    return;
+  vals = new std::pair<ValueVector*, ValueVector*>[n];
+  memset((void*)vals, 0, sizeof(*vals) * n);
+}
+
+CFGBlockValues::~CFGBlockValues() {
+  unsigned n = cfg.getNumBlockIDs();
+  if (n == 0)
+    return;
+  for (unsigned i = 0; i < n; ++i) {
+    delete vals[i].first;
+    delete vals[i].second;
+  }
+  delete [] vals;
+}
+
+void CFGBlockValues::computeSetOfDeclarations(const DeclContext &dc) {
+  declToIndex.computeMap(dc);
+  scratch.resize(declToIndex.size());
+}
+
+ValueVector &CFGBlockValues::lazyCreate(ValueVector *&bv) {
+  if (!bv)
+    bv = new ValueVector(declToIndex.size());
+  return *bv;
+}
+
+/// This function pattern matches for a '&&' or '||' that appears at
+/// the beginning of a CFGBlock that also (1) has a terminator and 
+/// (2) has no other elements.  If such an expression is found, it is returned.
+static const BinaryOperator *getLogicalOperatorInChain(const CFGBlock *block) {
+  if (block->empty())
+    return 0;
+
+  CFGElement front = block->front();
+  const CFGStmt *cstmt = front.getAs<CFGStmt>();
+  if (!cstmt)
+    return 0;
+
+  const BinaryOperator *b = dyn_cast_or_null<BinaryOperator>(cstmt->getStmt());
+  
+  if (!b || !b->isLogicalOp())
+    return 0;
+  
+  if (block->pred_size() == 2) {
+    if (block->getTerminatorCondition() == b) {
+      if (block->succ_size() == 2)
+      return b;
+    }
+    else if (block->size() == 1)
+      return b;
+  }
+
+  return 0;
+}
+
+ValueVector &CFGBlockValues::getValueVector(const CFGBlock *block,
+                                            const CFGBlock *dstBlock) {
+  unsigned idx = block->getBlockID();
+  if (dstBlock && getLogicalOperatorInChain(block)) {
+    if (*block->succ_begin() == dstBlock)
+      return lazyCreate(vals[idx].first);
+    assert(*(block->succ_begin()+1) == dstBlock);
+    return lazyCreate(vals[idx].second);
+  }
+
+  assert(vals[idx].second == 0);
+  return lazyCreate(vals[idx].first);
+}
+
+BVPair &CFGBlockValues::getValueVectors(const clang::CFGBlock *block,
+                                        bool shouldLazyCreate) {
+  unsigned idx = block->getBlockID();
+  lazyCreate(vals[idx].first);
+  if (shouldLazyCreate)
+    lazyCreate(vals[idx].second);
+  return vals[idx];
+}
+
+#if 0
+static void printVector(const CFGBlock *block, ValueVector &bv,
+                        unsigned num) {
+  
+  llvm::errs() << block->getBlockID() << " :";
+  for (unsigned i = 0; i < bv.size(); ++i) {
+    llvm::errs() << ' ' << bv[i];
+  }
+  llvm::errs() << " : " << num << '\n';
+}
+
+static void printVector(const char *name, ValueVector const &bv) {
+  llvm::errs() << name << " : ";
+  for (unsigned i = 0; i < bv.size(); ++i) {
+    llvm::errs() << ' ' << bv[i];
+  }
+  llvm::errs() << "\n";
+}
+#endif
+
+void CFGBlockValues::mergeIntoScratch(ValueVector const &source,
+                                      bool isFirst) {
+  if (isFirst)
+    scratch = source;
+  else
+    scratch |= source;
+}
+
+bool CFGBlockValues::updateValueVectorWithScratch(const CFGBlock *block) {
+  ValueVector &dst = getValueVector(block, 0);
+  bool changed = (dst != scratch);
+  if (changed)
+    dst = scratch;
+#if 0
+  printVector(block, scratch, 0);
+#endif
+  return changed;
+}
+
+bool CFGBlockValues::updateValueVectors(const CFGBlock *block,
+                                      const BVPair &newVals) {
+  BVPair &vals = getValueVectors(block, true);
+  bool changed = *newVals.first != *vals.first ||
+                 *newVals.second != *vals.second;
+  *vals.first = *newVals.first;
+  *vals.second = *newVals.second;
+#if 0
+  printVector(block, *vals.first, 1);
+  printVector(block, *vals.second, 2);
+#endif
+  return changed;
+}
+
+void CFGBlockValues::resetScratch() {
+  scratch.reset();
+}
+
+ValueVector::reference CFGBlockValues::operator[](const VarDecl *vd) {
+  const llvm::Optional<unsigned> &idx = declToIndex.getValueIndex(vd);
+  assert(idx.hasValue());
+  return scratch[idx.getValue()];
+}
+
+//------------------------------------------------------------------------====//
+// Worklist: worklist for dataflow analysis.
+//====------------------------------------------------------------------------//
+
+namespace {
+class DataflowWorklist {
+  SmallVector<const CFGBlock *, 20> worklist;
+  llvm::BitVector enqueuedBlocks;
+public:
+  DataflowWorklist(const CFG &cfg) : enqueuedBlocks(cfg.getNumBlockIDs()) {}
+  
+  void enqueueSuccessors(const CFGBlock *block);
+  const CFGBlock *dequeue();
+};
+}
+
+void DataflowWorklist::enqueueSuccessors(const clang::CFGBlock *block) {
+  unsigned OldWorklistSize = worklist.size();
+  for (CFGBlock::const_succ_iterator I = block->succ_begin(),
+       E = block->succ_end(); I != E; ++I) {
+    const CFGBlock *Successor = *I;
+    if (!Successor || enqueuedBlocks[Successor->getBlockID()])
+      continue;
+    worklist.push_back(Successor);
+    enqueuedBlocks[Successor->getBlockID()] = true;
+  }
+  if (OldWorklistSize == 0 || OldWorklistSize == worklist.size())
+    return;
+
+  // Rotate the newly added blocks to the start of the worklist so that it forms
+  // a proper queue when we pop off the end of the worklist.
+  std::rotate(worklist.begin(), worklist.begin() + OldWorklistSize,
+              worklist.end());
+}
+
+const CFGBlock *DataflowWorklist::dequeue() {
+  if (worklist.empty())
+    return 0;
+  const CFGBlock *b = worklist.back();
+  worklist.pop_back();
+  enqueuedBlocks[b->getBlockID()] = false;
+  return b;
+}
+
+//------------------------------------------------------------------------====//
+// Transfer function for uninitialized values analysis.
+//====------------------------------------------------------------------------//
+
+namespace {
+class FindVarResult {
+  const VarDecl *vd;
+  const DeclRefExpr *dr;
+public:
+  FindVarResult(VarDecl *vd, DeclRefExpr *dr) : vd(vd), dr(dr) {}
+  
+  const DeclRefExpr *getDeclRefExpr() const { return dr; }
+  const VarDecl *getDecl() const { return vd; }
+};
+  
+class TransferFunctions : public StmtVisitor<TransferFunctions> {
+  CFGBlockValues &vals;
+  const CFG &cfg;
+  AnalysisDeclContext &ac;
+  UninitVariablesHandler *handler;
+  
+  /// The last DeclRefExpr seen when analyzing a block.  Used to
+  /// cheat when detecting cases when the address of a variable is taken.
+  DeclRefExpr *lastDR;
+  
+  /// The last lvalue-to-rvalue conversion of a variable whose value
+  /// was uninitialized.  Normally this results in a warning, but it is
+  /// possible to either silence the warning in some cases, or we
+  /// propagate the uninitialized value.
+  CastExpr *lastLoad;
+  
+  /// For some expressions, we want to ignore any post-processing after
+  /// visitation.
+  bool skipProcessUses;
+  
+public:
+  TransferFunctions(CFGBlockValues &vals, const CFG &cfg,
+                    AnalysisDeclContext &ac,
+                    UninitVariablesHandler *handler)
+    : vals(vals), cfg(cfg), ac(ac), handler(handler),
+      lastDR(0), lastLoad(0),
+      skipProcessUses(false) {}
+  
+  void reportUninit(const DeclRefExpr *ex, const VarDecl *vd,
+                    bool isAlwaysUninit);
+
+  void VisitBlockExpr(BlockExpr *be);
+  void VisitDeclStmt(DeclStmt *ds);
+  void VisitDeclRefExpr(DeclRefExpr *dr);
+  void VisitUnaryOperator(UnaryOperator *uo);
+  void VisitBinaryOperator(BinaryOperator *bo);
+  void VisitCastExpr(CastExpr *ce);
+  void VisitObjCForCollectionStmt(ObjCForCollectionStmt *fs);
+  void Visit(Stmt *s);
+  
+  bool isTrackedVar(const VarDecl *vd) {
+    return ::isTrackedVar(vd, cast<DeclContext>(ac.getDecl()));
+  }
+  
+  FindVarResult findBlockVarDecl(Expr *ex);
+  
+  void ProcessUses(Stmt *s = 0);
+};
+}
+
+static const Expr *stripCasts(ASTContext &C, const Expr *Ex) {
+  while (Ex) {
+    Ex = Ex->IgnoreParenNoopCasts(C);
+    if (const CastExpr *CE = dyn_cast<CastExpr>(Ex)) {
+      if (CE->getCastKind() == CK_LValueBitCast) {
+        Ex = CE->getSubExpr();
+        continue;
+      }
+    }
+    break;
+  }
+  return Ex;
+}
+
+void TransferFunctions::reportUninit(const DeclRefExpr *ex,
+                                     const VarDecl *vd, bool isAlwaysUnit) {
+  if (handler) handler->handleUseOfUninitVariable(ex, vd, isAlwaysUnit);
+}
+
+FindVarResult TransferFunctions::findBlockVarDecl(Expr *ex) {
+  if (DeclRefExpr *dr = dyn_cast<DeclRefExpr>(ex->IgnoreParenCasts()))
+    if (VarDecl *vd = dyn_cast<VarDecl>(dr->getDecl()))
+      if (isTrackedVar(vd))
+        return FindVarResult(vd, dr);  
+  return FindVarResult(0, 0);
+}
+
+void TransferFunctions::VisitObjCForCollectionStmt(ObjCForCollectionStmt *fs) {
+  // This represents an initialization of the 'element' value.
+  Stmt *element = fs->getElement();
+  const VarDecl *vd = 0;
+  
+  if (DeclStmt *ds = dyn_cast<DeclStmt>(element)) {
+    vd = cast<VarDecl>(ds->getSingleDecl());
+    if (!isTrackedVar(vd))
+      vd = 0;
+  } else {
+    // Initialize the value of the reference variable.
+    const FindVarResult &res = findBlockVarDecl(cast<Expr>(element));
+    vd = res.getDecl();
+  }
+  
+  if (vd)
+    vals[vd] = Initialized;
+}
+
+void TransferFunctions::VisitBlockExpr(BlockExpr *be) {
+  const BlockDecl *bd = be->getBlockDecl();
+  for (BlockDecl::capture_const_iterator i = bd->capture_begin(),
+        e = bd->capture_end() ; i != e; ++i) {
+    const VarDecl *vd = i->getVariable();
+    if (!isTrackedVar(vd))
+      continue;
+    if (i->isByRef()) {
+      vals[vd] = Initialized;
+      continue;
+    }
+    Value v = vals[vd];
+    if (handler && isUninitialized(v))
+      handler->handleUseOfUninitVariable(be, vd, isAlwaysUninit(v));
+  }
+}
+
+void TransferFunctions::VisitDeclRefExpr(DeclRefExpr *dr) {
+  // Record the last DeclRefExpr seen.  This is an lvalue computation.
+  // We use this value to later detect if a variable "escapes" the analysis.
+  if (const VarDecl *vd = dyn_cast<VarDecl>(dr->getDecl()))
+    if (isTrackedVar(vd)) {
+      ProcessUses();
+      lastDR = dr;
+    }
+}
+
+void TransferFunctions::VisitDeclStmt(DeclStmt *ds) {
+  for (DeclStmt::decl_iterator DI = ds->decl_begin(), DE = ds->decl_end();
+       DI != DE; ++DI) {
+    if (VarDecl *vd = dyn_cast<VarDecl>(*DI)) {
+      if (isTrackedVar(vd)) {
+        if (Expr *init = vd->getInit()) {
+          // If the initializer consists solely of a reference to itself, we
+          // explicitly mark the variable as uninitialized. This allows code
+          // like the following:
+          //
+          //   int x = x;
+          //
+          // to deliberately leave a variable uninitialized. Different analysis
+          // clients can detect this pattern and adjust their reporting
+          // appropriately, but we need to continue to analyze subsequent uses
+          // of the variable.
+          if (init == lastLoad) {
+            const DeclRefExpr *DR
+              = cast<DeclRefExpr>(stripCasts(ac.getASTContext(),
+                                             lastLoad->getSubExpr()));
+            if (DR->getDecl() == vd) {
+              // int x = x;
+              // Propagate uninitialized value, but don't immediately report
+              // a problem.
+              vals[vd] = Uninitialized;
+              lastLoad = 0;
+              lastDR = 0;
+              if (handler)
+                handler->handleSelfInit(vd);
+              return;
+            }
+          }
+
+          // All other cases: treat the new variable as initialized.
+          // This is a minor optimization to reduce the propagation
+          // of the analysis, since we will have already reported
+          // the use of the uninitialized value (which visiting the
+          // initializer).
+          vals[vd] = Initialized;
+        }
+      }
+    }
+  }
+}
+
+void TransferFunctions::VisitBinaryOperator(clang::BinaryOperator *bo) {
+  if (bo->isAssignmentOp()) {
+    const FindVarResult &res = findBlockVarDecl(bo->getLHS());
+    if (const VarDecl *vd = res.getDecl()) {
+      ValueVector::reference val = vals[vd];
+      if (isUninitialized(val)) {
+        if (bo->getOpcode() != BO_Assign)
+          reportUninit(res.getDeclRefExpr(), vd, isAlwaysUninit(val));
+        else
+          val = Initialized;
+      }
+    }
+  }
+}
+
+void TransferFunctions::VisitUnaryOperator(clang::UnaryOperator *uo) {
+  switch (uo->getOpcode()) {
+    case clang::UO_PostDec:
+    case clang::UO_PostInc:
+    case clang::UO_PreDec:
+    case clang::UO_PreInc: {
+      const FindVarResult &res = findBlockVarDecl(uo->getSubExpr());
+      if (const VarDecl *vd = res.getDecl()) {
+        assert(res.getDeclRefExpr() == lastDR);
+        // We null out lastDR to indicate we have fully processed it
+        // and we don't want the auto-value setting in Visit().
+        lastDR = 0;
+
+        ValueVector::reference val = vals[vd];
+        if (isUninitialized(val))
+          reportUninit(res.getDeclRefExpr(), vd, isAlwaysUninit(val));
+      }
+      break;
+    }
+    default:
+      break;
+  }
+}
+
+void TransferFunctions::VisitCastExpr(clang::CastExpr *ce) {
+  if (ce->getCastKind() == CK_LValueToRValue) {
+    const FindVarResult &res = findBlockVarDecl(ce->getSubExpr());
+    if (res.getDecl()) {
+      assert(res.getDeclRefExpr() == lastDR);
+      lastLoad = ce;
+    }
+  }
+  else if (ce->getCastKind() == CK_NoOp ||
+           ce->getCastKind() == CK_LValueBitCast) {
+    skipProcessUses = true;
+  }
+  else if (CStyleCastExpr *cse = dyn_cast<CStyleCastExpr>(ce)) {
+    if (cse->getType()->isVoidType()) {
+      // e.g. (void) x;
+      if (lastLoad == cse->getSubExpr()) {
+        // Squelch any detected load of an uninitialized value if
+        // we cast it to void.
+        lastLoad = 0;
+        lastDR = 0;
+      }
+    }
+  }
+}
+
+void TransferFunctions::Visit(clang::Stmt *s) {
+  skipProcessUses = false;
+  StmtVisitor<TransferFunctions>::Visit(s);
+  if (!skipProcessUses)
+    ProcessUses(s);
+}
+
+void TransferFunctions::ProcessUses(Stmt *s) {
+  // This method is typically called after visiting a CFGElement statement
+  // in the CFG.  We delay processing of reporting many loads of uninitialized
+  // values until here.
+  if (lastLoad) {
+    // If we just visited the lvalue-to-rvalue cast, there is nothing
+    // left to do.
+    if (lastLoad == s)
+      return;
+
+    const DeclRefExpr *DR =
+      cast<DeclRefExpr>(stripCasts(ac.getASTContext(),
+                                   lastLoad->getSubExpr()));
+    const VarDecl *VD = cast<VarDecl>(DR->getDecl());
+
+    // If we reach here, we may have seen a load of an uninitialized value
+    // and it hasn't been casted to void or otherwise handled.  In this
+    // situation, report the incident.
+    if (isUninitialized(vals[VD]))
+      reportUninit(DR, VD, isAlwaysUninit(vals[VD]));
+
+    lastLoad = 0;
+
+    if (DR == lastDR) {
+      lastDR = 0;
+      return;
+    }
+  }
+
+  // Any other uses of 'lastDR' involve taking an lvalue of variable.
+  // In this case, it "escapes" the analysis.
+  if (lastDR && lastDR != s) {
+    vals[cast<VarDecl>(lastDR->getDecl())] = Initialized;
+    lastDR = 0;
+  }
+}
+
+//------------------------------------------------------------------------====//
+// High-level "driver" logic for uninitialized values analysis.
+//====------------------------------------------------------------------------//
+
+static bool runOnBlock(const CFGBlock *block, const CFG &cfg,
+                       AnalysisDeclContext &ac, CFGBlockValues &vals,
+                       llvm::BitVector &wasAnalyzed,
+                       UninitVariablesHandler *handler = 0) {
+  
+  wasAnalyzed[block->getBlockID()] = true;
+  
+  if (const BinaryOperator *b = getLogicalOperatorInChain(block)) {
+    CFGBlock::const_pred_iterator itr = block->pred_begin();
+    BVPair vA = vals.getValueVectors(*itr, false);
+    ++itr;
+    BVPair vB = vals.getValueVectors(*itr, false);
+
+    BVPair valsAB;
+    
+    if (b->getOpcode() == BO_LAnd) {
+      // Merge the 'F' bits from the first and second.
+      vals.mergeIntoScratch(*(vA.second ? vA.second : vA.first), true);
+      vals.mergeIntoScratch(*(vB.second ? vB.second : vB.first), false);
+      valsAB.first = vA.first;
+      valsAB.second = &vals.getScratch();
+    } else {
+      // Merge the 'T' bits from the first and second.
+      assert(b->getOpcode() == BO_LOr);
+      vals.mergeIntoScratch(*vA.first, true);
+      vals.mergeIntoScratch(*vB.first, false);
+      valsAB.first = &vals.getScratch();
+      valsAB.second = vA.second ? vA.second : vA.first;
+    }
+    return vals.updateValueVectors(block, valsAB);
+  }
+
+  // Default behavior: merge in values of predecessor blocks.
+  vals.resetScratch();
+  bool isFirst = true;
+  for (CFGBlock::const_pred_iterator I = block->pred_begin(),
+       E = block->pred_end(); I != E; ++I) {
+    const CFGBlock *pred = *I;
+    if (wasAnalyzed[pred->getBlockID()]) {
+      vals.mergeIntoScratch(vals.getValueVector(pred, block), isFirst);
+      isFirst = false;
+    }
+  }
+  // Apply the transfer function.
+  TransferFunctions tf(vals, cfg, ac, handler);
+  for (CFGBlock::const_iterator I = block->begin(), E = block->end(); 
+       I != E; ++I) {
+    if (const CFGStmt *cs = dyn_cast<CFGStmt>(&*I)) {
+      tf.Visit(const_cast<Stmt*>(cs->getStmt()));
+    }
+  }
+  tf.ProcessUses();
+  return vals.updateValueVectorWithScratch(block);
+}
+
+void clang::runUninitializedVariablesAnalysis(
+    const DeclContext &dc,
+    const CFG &cfg,
+    AnalysisDeclContext &ac,
+    UninitVariablesHandler &handler,
+    UninitVariablesAnalysisStats &stats) {
+  CFGBlockValues vals(cfg);
+  vals.computeSetOfDeclarations(dc);
+  if (vals.hasNoDeclarations())
+    return;
+
+  stats.NumVariablesAnalyzed = vals.getNumEntries();
+
+  // Mark all variables uninitialized at the entry.
+  const CFGBlock &entry = cfg.getEntry();
+  for (CFGBlock::const_succ_iterator i = entry.succ_begin(), 
+        e = entry.succ_end(); i != e; ++i) {
+    if (const CFGBlock *succ = *i) {
+      ValueVector &vec = vals.getValueVector(&entry, succ);
+      const unsigned n = vals.getNumEntries();
+      for (unsigned j = 0; j < n ; ++j) {
+        vec[j] = Uninitialized;
+      }
+    }
+  }
+
+  // Proceed with the workist.
+  DataflowWorklist worklist(cfg);
+  llvm::BitVector previouslyVisited(cfg.getNumBlockIDs());
+  worklist.enqueueSuccessors(&cfg.getEntry());
+  llvm::BitVector wasAnalyzed(cfg.getNumBlockIDs(), false);
+  wasAnalyzed[cfg.getEntry().getBlockID()] = true;
+
+  while (const CFGBlock *block = worklist.dequeue()) {
+    // Did the block change?
+    bool changed = runOnBlock(block, cfg, ac, vals, wasAnalyzed);
+    ++stats.NumBlockVisits;
+    if (changed || !previouslyVisited[block->getBlockID()])
+      worklist.enqueueSuccessors(block);    
+    previouslyVisited[block->getBlockID()] = true;
+  }
+  
+  // Run through the blocks one more time, and report uninitialized variabes.
+  for (CFG::const_iterator BI = cfg.begin(), BE = cfg.end(); BI != BE; ++BI) {
+    const CFGBlock *block = *BI;
+    if (wasAnalyzed[block->getBlockID()]) {
+      runOnBlock(block, cfg, ac, vals, wasAnalyzed, &handler);
+      ++stats.NumBlockVisits;
+    }
+  }
+}
+
+UninitVariablesHandler::~UninitVariablesHandler() {}