1 files changed, 684 insertions, 0 deletions
diff --git a/contrib/llvm/tools/clang/lib/Analysis/LiveVariables.cpp b/contrib/llvm/tools/clang/lib/Analysis/LiveVariables.cpp
new file mode 100644
index 000000000000..afe2d264907f
--- /dev/null
+++ b/contrib/llvm/tools/clang/lib/Analysis/LiveVariables.cpp
@@ -0,0 +1,684 @@
+//=- LiveVariables.cpp - Live Variable Analysis for Source CFGs ----------*-==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements Live Variables analysis for source-level CFGs.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Analysis/Analyses/LiveVariables.h"
+#include "clang/AST/Stmt.h"
+#include "clang/AST/StmtVisitor.h"
+#include "clang/Analysis/Analyses/PostOrderCFGView.h"
+#include "clang/Analysis/AnalysisDeclContext.h"
+#include "clang/Analysis/CFG.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/PostOrderIterator.h"
+#include "llvm/ADT/PriorityQueue.h"
+#include "llvm/Support/raw_ostream.h"
+#include <algorithm>
+#include <vector>
+
+using namespace clang;
+
+namespace {
+
+class DataflowWorklist {
+  llvm::BitVector enqueuedBlocks;
+  PostOrderCFGView *POV;
+  llvm::PriorityQueue<const CFGBlock *, SmallVector<const CFGBlock *, 20>,
+                      PostOrderCFGView::BlockOrderCompare> worklist;
+
+public:
+  DataflowWorklist(const CFG &cfg, AnalysisDeclContext &Ctx)
+    : enqueuedBlocks(cfg.getNumBlockIDs()),
+      POV(Ctx.getAnalysis<PostOrderCFGView>()),
+      worklist(POV->getComparator()) {}
+
+  void enqueueBlock(const CFGBlock *block);
+  void enqueuePredecessors(const CFGBlock *block);
+
+  const CFGBlock *dequeue();
+};
+
+}
+
+void DataflowWorklist::enqueueBlock(const clang::CFGBlock *block) {
+  if (block && !enqueuedBlocks[block->getBlockID()]) {
+    enqueuedBlocks[block->getBlockID()] = true;
+    worklist.push(block);
+  }
+}
+
+void DataflowWorklist::enqueuePredecessors(const clang::CFGBlock *block) {
+  for (CFGBlock::const_pred_iterator I = block->pred_begin(),
+       E = block->pred_end(); I != E; ++I) {
+    enqueueBlock(*I);
+  }
+}
+
+const CFGBlock *DataflowWorklist::dequeue() {
+  if (worklist.empty())
+    return nullptr;
+  const CFGBlock *b = worklist.top();
+  worklist.pop();
+  enqueuedBlocks[b->getBlockID()] = false;
+  return b;
+}
+
+namespace {
+class LiveVariablesImpl {
+public:
+  AnalysisDeclContext &analysisContext;
+  llvm::ImmutableSet<const Stmt *>::Factory SSetFact;
+  llvm::ImmutableSet<const VarDecl *>::Factory DSetFact;
+  llvm::ImmutableSet<const BindingDecl *>::Factory BSetFact;
+  llvm::DenseMap<const CFGBlock *, LiveVariables::LivenessValues> blocksEndToLiveness;
+  llvm::DenseMap<const CFGBlock *, LiveVariables::LivenessValues> blocksBeginToLiveness;
+  llvm::DenseMap<const Stmt *, LiveVariables::LivenessValues> stmtsToLiveness;
+  llvm::DenseMap<const DeclRefExpr *, unsigned> inAssignment;
+  const bool killAtAssign;
+
+  LiveVariables::LivenessValues
+  merge(LiveVariables::LivenessValues valsA,
+        LiveVariables::LivenessValues valsB);
+
+  LiveVariables::LivenessValues
+  runOnBlock(const CFGBlock *block, LiveVariables::LivenessValues val,
+             LiveVariables::Observer *obs = nullptr);
+
+  void dumpBlockLiveness(const SourceManager& M);
+  void dumpStmtLiveness(const SourceManager& M);
+
+  LiveVariablesImpl(AnalysisDeclContext &ac, bool KillAtAssign)
+    : analysisContext(ac),
+      SSetFact(false), // Do not canonicalize ImmutableSets by default.
+      DSetFact(false), // This is a *major* performance win.
+      BSetFact(false),
+      killAtAssign(KillAtAssign) {}
+};
+}
+
+static LiveVariablesImpl &getImpl(void *x) {
+  return *((LiveVariablesImpl *) x);
+}
+
+//===----------------------------------------------------------------------===//
+// Operations and queries on LivenessValues.
+//===----------------------------------------------------------------------===//
+
+bool LiveVariables::LivenessValues::isLive(const Stmt *S) const {
+  return liveStmts.contains(S);
+}
+
+bool LiveVariables::LivenessValues::isLive(const VarDecl *D) const {
+  if (const auto *DD = dyn_cast<DecompositionDecl>(D)) {
+    bool alive = false;
+    for (const BindingDecl *BD : DD->bindings())
+      alive |= liveBindings.contains(BD);
+    return alive;
+  }
+  return liveDecls.contains(D);
+}
+
+namespace {
+  template <typename SET>
+  SET mergeSets(SET A, SET B) {
+    if (A.isEmpty())
+      return B;
+
+    for (typename SET::iterator it = B.begin(), ei = B.end(); it != ei; ++it) {
+      A = A.add(*it);
+    }
+    return A;
+  }
+}
+
+void LiveVariables::Observer::anchor() { }
+
+LiveVariables::LivenessValues
+LiveVariablesImpl::merge(LiveVariables::LivenessValues valsA,
+                         LiveVariables::LivenessValues valsB) {
+
+  llvm::ImmutableSetRef<const Stmt *>
+    SSetRefA(valsA.liveStmts.getRootWithoutRetain(), SSetFact.getTreeFactory()),
+    SSetRefB(valsB.liveStmts.getRootWithoutRetain(), SSetFact.getTreeFactory());
+
+
+  llvm::ImmutableSetRef<const VarDecl *>
+    DSetRefA(valsA.liveDecls.getRootWithoutRetain(), DSetFact.getTreeFactory()),
+    DSetRefB(valsB.liveDecls.getRootWithoutRetain(), DSetFact.getTreeFactory());
+
+  llvm::ImmutableSetRef<const BindingDecl *>
+    BSetRefA(valsA.liveBindings.getRootWithoutRetain(), BSetFact.getTreeFactory()),
+    BSetRefB(valsB.liveBindings.getRootWithoutRetain(), BSetFact.getTreeFactory());
+
+  SSetRefA = mergeSets(SSetRefA, SSetRefB);
+  DSetRefA = mergeSets(DSetRefA, DSetRefB);
+  BSetRefA = mergeSets(BSetRefA, BSetRefB);
+
+  // asImmutableSet() canonicalizes the tree, allowing us to do an easy
+  // comparison afterwards.
+  return LiveVariables::LivenessValues(SSetRefA.asImmutableSet(),
+                                       DSetRefA.asImmutableSet(),
+                                       BSetRefA.asImmutableSet());
+}
+
+bool LiveVariables::LivenessValues::equals(const LivenessValues &V) const {
+  return liveStmts == V.liveStmts && liveDecls == V.liveDecls;
+}
+
+//===----------------------------------------------------------------------===//
+// Query methods.
+//===----------------------------------------------------------------------===//
+
+static bool isAlwaysAlive(const VarDecl *D) {
+  return D->hasGlobalStorage();
+}
+
+bool LiveVariables::isLive(const CFGBlock *B, const VarDecl *D) {
+  return isAlwaysAlive(D) || getImpl(impl).blocksEndToLiveness[B].isLive(D);
+}
+
+bool LiveVariables::isLive(const Stmt *S, const VarDecl *D) {
+  return isAlwaysAlive(D) || getImpl(impl).stmtsToLiveness[S].isLive(D);
+}
+
+bool LiveVariables::isLive(const Stmt *Loc, const Stmt *S) {
+  return getImpl(impl).stmtsToLiveness[Loc].isLive(S);
+}
+
+//===----------------------------------------------------------------------===//
+// Dataflow computation.
+//===----------------------------------------------------------------------===//
+
+namespace {
+class TransferFunctions : public StmtVisitor<TransferFunctions> {
+  LiveVariablesImpl &LV;
+  LiveVariables::LivenessValues &val;
+  LiveVariables::Observer *observer;
+  const CFGBlock *currentBlock;
+public:
+  TransferFunctions(LiveVariablesImpl &im,
+                    LiveVariables::LivenessValues &Val,
+                    LiveVariables::Observer *Observer,
+                    const CFGBlock *CurrentBlock)
+  : LV(im), val(Val), observer(Observer), currentBlock(CurrentBlock) {}
+
+  void VisitBinaryOperator(BinaryOperator *BO);
+  void VisitBlockExpr(BlockExpr *BE);
+  void VisitDeclRefExpr(DeclRefExpr *DR);
+  void VisitDeclStmt(DeclStmt *DS);
+  void VisitObjCForCollectionStmt(ObjCForCollectionStmt *OS);
+  void VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *UE);
+  void VisitUnaryOperator(UnaryOperator *UO);
+  void Visit(Stmt *S);
+};
+}
+
+static const VariableArrayType *FindVA(QualType Ty) {
+  const Type *ty = Ty.getTypePtr();
+  while (const ArrayType *VT = dyn_cast<ArrayType>(ty)) {
+    if (const VariableArrayType *VAT = dyn_cast<VariableArrayType>(VT))
+      if (VAT->getSizeExpr())
+        return VAT;
+
+    ty = VT->getElementType().getTypePtr();
+  }
+
+  return nullptr;
+}
+
+static const Stmt *LookThroughStmt(const Stmt *S) {
+  while (S) {
+    if (const Expr *Ex = dyn_cast<Expr>(S))
+      S = Ex->IgnoreParens();
+    if (const FullExpr *FE = dyn_cast<FullExpr>(S)) {
+      S = FE->getSubExpr();
+      continue;
+    }
+    if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(S)) {
+      S = OVE->getSourceExpr();
+      continue;
+    }
+    break;
+  }
+  return S;
+}
+
+static void AddLiveStmt(llvm::ImmutableSet<const Stmt *> &Set,
+                        llvm::ImmutableSet<const Stmt *>::Factory &F,
+                        const Stmt *S) {
+  Set = F.add(Set, LookThroughStmt(S));
+}
+
+void TransferFunctions::Visit(Stmt *S) {
+  if (observer)
+    observer->observeStmt(S, currentBlock, val);
+
+  StmtVisitor<TransferFunctions>::Visit(S);
+
+  if (isa<Expr>(S)) {
+    val.liveStmts = LV.SSetFact.remove(val.liveStmts, S);
+  }
+
+  // Mark all children expressions live.
+
+  switch (S->getStmtClass()) {
+    default:
+      break;
+    case Stmt::StmtExprClass: {
+      // For statement expressions, look through the compound statement.
+      S = cast<StmtExpr>(S)->getSubStmt();
+      break;
+    }
+    case Stmt::CXXMemberCallExprClass: {
+      // Include the implicit "this" pointer as being live.
+      CXXMemberCallExpr *CE = cast<CXXMemberCallExpr>(S);
+      if (Expr *ImplicitObj = CE->getImplicitObjectArgument()) {
+        AddLiveStmt(val.liveStmts, LV.SSetFact, ImplicitObj);
+      }
+      break;
+    }
+    case Stmt::ObjCMessageExprClass: {
+      // In calls to super, include the implicit "self" pointer as being live.
+      ObjCMessageExpr *CE = cast<ObjCMessageExpr>(S);
+      if (CE->getReceiverKind() == ObjCMessageExpr::SuperInstance)
+        val.liveDecls = LV.DSetFact.add(val.liveDecls,
+                                        LV.analysisContext.getSelfDecl());
+      break;
+    }
+    case Stmt::DeclStmtClass: {
+      const DeclStmt *DS = cast<DeclStmt>(S);
+      if (const VarDecl *VD = dyn_cast<VarDecl>(DS->getSingleDecl())) {
+        for (const VariableArrayType* VA = FindVA(VD->getType());
+             VA != nullptr; VA = FindVA(VA->getElementType())) {
+          AddLiveStmt(val.liveStmts, LV.SSetFact, VA->getSizeExpr());
+        }
+      }
+      break;
+    }
+    case Stmt::PseudoObjectExprClass: {
+      // A pseudo-object operation only directly consumes its result
+      // expression.
+      Expr *child = cast<PseudoObjectExpr>(S)->getResultExpr();
+      if (!child) return;
+      if (OpaqueValueExpr *OV = dyn_cast<OpaqueValueExpr>(child))
+        child = OV->getSourceExpr();
+      child = child->IgnoreParens();
+      val.liveStmts = LV.SSetFact.add(val.liveStmts, child);
+      return;
+    }
+
+    // FIXME: These cases eventually shouldn't be needed.
+    case Stmt::ExprWithCleanupsClass: {
+      S = cast<ExprWithCleanups>(S)->getSubExpr();
+      break;
+    }
+    case Stmt::CXXBindTemporaryExprClass: {
+      S = cast<CXXBindTemporaryExpr>(S)->getSubExpr();
+      break;
+    }
+    case Stmt::UnaryExprOrTypeTraitExprClass: {
+      // No need to unconditionally visit subexpressions.
+      return;
+    }
+    case Stmt::IfStmtClass: {
+      // If one of the branches is an expression rather than a compound
+      // statement, it will be bad if we mark it as live at the terminator
+      // of the if-statement (i.e., immediately after the condition expression).
+      AddLiveStmt(val.liveStmts, LV.SSetFact, cast<IfStmt>(S)->getCond());
+      return;
+    }
+    case Stmt::WhileStmtClass: {
+      // If the loop body is an expression rather than a compound statement,
+      // it will be bad if we mark it as live at the terminator of the loop
+      // (i.e., immediately after the condition expression).
+      AddLiveStmt(val.liveStmts, LV.SSetFact, cast<WhileStmt>(S)->getCond());
+      return;
+    }
+    case Stmt::DoStmtClass: {
+      // If the loop body is an expression rather than a compound statement,
+      // it will be bad if we mark it as live at the terminator of the loop
+      // (i.e., immediately after the condition expression).
+      AddLiveStmt(val.liveStmts, LV.SSetFact, cast<DoStmt>(S)->getCond());
+      return;
+    }
+    case Stmt::ForStmtClass: {
+      // If the loop body is an expression rather than a compound statement,
+      // it will be bad if we mark it as live at the terminator of the loop
+      // (i.e., immediately after the condition expression).
+      AddLiveStmt(val.liveStmts, LV.SSetFact, cast<ForStmt>(S)->getCond());
+      return;
+    }
+
+  }
+
+  for (Stmt *Child : S->children()) {
+    if (Child)
+      AddLiveStmt(val.liveStmts, LV.SSetFact, Child);
+  }
+}
+
+static bool writeShouldKill(const VarDecl *VD) {
+  return VD && !VD->getType()->isReferenceType() &&
+    !isAlwaysAlive(VD);
+}
+
+void TransferFunctions::VisitBinaryOperator(BinaryOperator *B) {
+  if (B->isAssignmentOp()) {
+    if (!LV.killAtAssign)
+      return;
+
+    // Assigning to a variable?
+    Expr *LHS = B->getLHS()->IgnoreParens();
+
+    if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(LHS)) {
+      const Decl* D = DR->getDecl();
+      bool Killed = false;
+
+      if (const BindingDecl* BD = dyn_cast<BindingDecl>(D)) {
+        Killed = !BD->getType()->isReferenceType();
+        if (Killed)
+          val.liveBindings = LV.BSetFact.remove(val.liveBindings, BD);
+      } else if (const auto *VD = dyn_cast<VarDecl>(D)) {
+        Killed = writeShouldKill(VD);
+        if (Killed)
+          val.liveDecls = LV.DSetFact.remove(val.liveDecls, VD);
+
+      }
+
+      if (Killed && observer)
+        observer->observerKill(DR);
+    }
+  }
+}
+
+void TransferFunctions::VisitBlockExpr(BlockExpr *BE) {
+  for (const VarDecl *VD :
+       LV.analysisContext.getReferencedBlockVars(BE->getBlockDecl())) {
+    if (isAlwaysAlive(VD))
+      continue;
+    val.liveDecls = LV.DSetFact.add(val.liveDecls, VD);
+  }
+}
+
+void TransferFunctions::VisitDeclRefExpr(DeclRefExpr *DR) {
+  const Decl* D = DR->getDecl();
+  bool InAssignment = LV.inAssignment[DR];
+  if (const auto *BD = dyn_cast<BindingDecl>(D)) {
+    if (!InAssignment)
+      val.liveBindings = LV.BSetFact.add(val.liveBindings, BD);
+  } else if (const auto *VD = dyn_cast<VarDecl>(D)) {
+    if (!InAssignment && !isAlwaysAlive(VD))
+      val.liveDecls = LV.DSetFact.add(val.liveDecls, VD);
+  }
+}
+
+void TransferFunctions::VisitDeclStmt(DeclStmt *DS) {
+  for (const auto *DI : DS->decls()) {
+    if (const auto *DD = dyn_cast<DecompositionDecl>(DI)) {
+      for (const auto *BD : DD->bindings())
+        val.liveBindings = LV.BSetFact.remove(val.liveBindings, BD);
+    } else if (const auto *VD = dyn_cast<VarDecl>(DI)) {
+      if (!isAlwaysAlive(VD))
+        val.liveDecls = LV.DSetFact.remove(val.liveDecls, VD);
+    }
+  }
+}
+
+void TransferFunctions::VisitObjCForCollectionStmt(ObjCForCollectionStmt *OS) {
+  // Kill the iteration variable.
+  DeclRefExpr *DR = nullptr;
+  const VarDecl *VD = nullptr;
+
+  Stmt *element = OS->getElement();
+  if (DeclStmt *DS = dyn_cast<DeclStmt>(element)) {
+    VD = cast<VarDecl>(DS->getSingleDecl());
+  }
+  else if ((DR = dyn_cast<DeclRefExpr>(cast<Expr>(element)->IgnoreParens()))) {
+    VD = cast<VarDecl>(DR->getDecl());
+  }
+
+  if (VD) {
+    val.liveDecls = LV.DSetFact.remove(val.liveDecls, VD);
+    if (observer && DR)
+      observer->observerKill(DR);
+  }
+}
+
+void TransferFunctions::
+VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *UE)
+{
+  // While sizeof(var) doesn't technically extend the liveness of 'var', it
+  // does extent the liveness of metadata if 'var' is a VariableArrayType.
+  // We handle that special case here.
+  if (UE->getKind() != UETT_SizeOf || UE->isArgumentType())
+    return;
+
+  const Expr *subEx = UE->getArgumentExpr();
+  if (subEx->getType()->isVariableArrayType()) {
+    assert(subEx->isLValue());
+    val.liveStmts = LV.SSetFact.add(val.liveStmts, subEx->IgnoreParens());
+  }
+}
+
+void TransferFunctions::VisitUnaryOperator(UnaryOperator *UO) {
+  // Treat ++/-- as a kill.
+  // Note we don't actually have to do anything if we don't have an observer,
+  // since a ++/-- acts as both a kill and a "use".
+  if (!observer)
+    return;
+
+  switch (UO->getOpcode()) {
+  default:
+    return;
+  case UO_PostInc:
+  case UO_PostDec:
+  case UO_PreInc:
+  case UO_PreDec:
+    break;
+  }
+
+  if (auto *DR = dyn_cast<DeclRefExpr>(UO->getSubExpr()->IgnoreParens())) {
+    const Decl *D = DR->getDecl();
+    if (isa<VarDecl>(D) || isa<BindingDecl>(D)) {
+      // Treat ++/-- as a kill.
+      observer->observerKill(DR);
+    }
+  }
+}
+
+LiveVariables::LivenessValues
+LiveVariablesImpl::runOnBlock(const CFGBlock *block,
+                              LiveVariables::LivenessValues val,
+                              LiveVariables::Observer *obs) {
+
+  TransferFunctions TF(*this, val, obs, block);
+
+  // Visit the terminator (if any).
+  if (const Stmt *term = block->getTerminator())
+    TF.Visit(const_cast<Stmt*>(term));
+
+  // Apply the transfer function for all Stmts in the block.
+  for (CFGBlock::const_reverse_iterator it = block->rbegin(),
+       ei = block->rend(); it != ei; ++it) {
+    const CFGElement &elem = *it;
+
+    if (Optional<CFGAutomaticObjDtor> Dtor =
+            elem.getAs<CFGAutomaticObjDtor>()) {
+      val.liveDecls = DSetFact.add(val.liveDecls, Dtor->getVarDecl());
+      continue;
+    }
+
+    if (!elem.getAs<CFGStmt>())
+      continue;
+
+    const Stmt *S = elem.castAs<CFGStmt>().getStmt();
+    TF.Visit(const_cast<Stmt*>(S));
+    stmtsToLiveness[S] = val;
+  }
+  return val;
+}
+
+void LiveVariables::runOnAllBlocks(LiveVariables::Observer &obs) {
+  const CFG *cfg = getImpl(impl).analysisContext.getCFG();
+  for (CFG::const_iterator it = cfg->begin(), ei = cfg->end(); it != ei; ++it)
+    getImpl(impl).runOnBlock(*it, getImpl(impl).blocksEndToLiveness[*it], &obs);
+}
+
+LiveVariables::LiveVariables(void *im) : impl(im) {}
+
+LiveVariables::~LiveVariables() {
+  delete (LiveVariablesImpl*) impl;
+}
+
+LiveVariables *
+LiveVariables::computeLiveness(AnalysisDeclContext &AC,
+                                 bool killAtAssign) {
+
+  // No CFG?  Bail out.
+  CFG *cfg = AC.getCFG();
+  if (!cfg)
+    return nullptr;
+
+  // The analysis currently has scalability issues for very large CFGs.
+  // Bail out if it looks too large.
+  if (cfg->getNumBlockIDs() > 300000)
+    return nullptr;
+
+  LiveVariablesImpl *LV = new LiveVariablesImpl(AC, killAtAssign);
+
+  // Construct the dataflow worklist.  Enqueue the exit block as the
+  // start of the analysis.
+  DataflowWorklist worklist(*cfg, AC);
+  llvm::BitVector everAnalyzedBlock(cfg->getNumBlockIDs());
+
+  // FIXME: we should enqueue using post order.
+  for (CFG::const_iterator it = cfg->begin(), ei = cfg->end(); it != ei; ++it) {
+    const CFGBlock *block = *it;
+    worklist.enqueueBlock(block);
+
+    // FIXME: Scan for DeclRefExprs using in the LHS of an assignment.
+    // We need to do this because we lack context in the reverse analysis
+    // to determine if a DeclRefExpr appears in such a context, and thus
+    // doesn't constitute a "use".
+    if (killAtAssign)
+      for (CFGBlock::const_iterator bi = block->begin(), be = block->end();
+           bi != be; ++bi) {
+        if (Optional<CFGStmt> cs = bi->getAs<CFGStmt>()) {
+          const Stmt* stmt = cs->getStmt();
+          if (const auto *BO = dyn_cast<BinaryOperator>(stmt)) {
+            if (BO->getOpcode() == BO_Assign) {
+              if (const auto *DR =
+                    dyn_cast<DeclRefExpr>(BO->getLHS()->IgnoreParens())) {
+                LV->inAssignment[DR] = 1;
+              }
+            }
+          }
+        }
+      }
+  }
+
+  while (const CFGBlock *block = worklist.dequeue()) {
+    // Determine if the block's end value has changed.  If not, we
+    // have nothing left to do for this block.
+    LivenessValues &prevVal = LV->blocksEndToLiveness[block];
+
+    // Merge the values of all successor blocks.
+    LivenessValues val;
+    for (CFGBlock::const_succ_iterator it = block->succ_begin(),
+                                       ei = block->succ_end(); it != ei; ++it) {
+      if (const CFGBlock *succ = *it) {
+        val = LV->merge(val, LV->blocksBeginToLiveness[succ]);
+      }
+    }
+
+    if (!everAnalyzedBlock[block->getBlockID()])
+      everAnalyzedBlock[block->getBlockID()] = true;
+    else if (prevVal.equals(val))
+      continue;
+
+    prevVal = val;
+
+    // Update the dataflow value for the start of this block.
+    LV->blocksBeginToLiveness[block] = LV->runOnBlock(block, val);
+
+    // Enqueue the value to the predecessors.
+    worklist.enqueuePredecessors(block);
+  }
+
+  return new LiveVariables(LV);
+}
+
+void LiveVariables::dumpBlockLiveness(const SourceManager &M) {
+  getImpl(impl).dumpBlockLiveness(M);
+}
+
+void LiveVariablesImpl::dumpBlockLiveness(const SourceManager &M) {
+  std::vector<const CFGBlock *> vec;
+  for (llvm::DenseMap<const CFGBlock *, LiveVariables::LivenessValues>::iterator
+       it = blocksEndToLiveness.begin(), ei = blocksEndToLiveness.end();
+       it != ei; ++it) {
+    vec.push_back(it->first);
+  }
+  llvm::sort(vec, [](const CFGBlock *A, const CFGBlock *B) {
+    return A->getBlockID() < B->getBlockID();
+  });
+
+  std::vector<const VarDecl*> declVec;
+
+  for (std::vector<const CFGBlock *>::iterator
+        it = vec.begin(), ei = vec.end(); it != ei; ++it) {
+    llvm::errs() << "\n[ B" << (*it)->getBlockID()
+                 << " (live variables at block exit) ]\n";
+
+    LiveVariables::LivenessValues vals = blocksEndToLiveness[*it];
+    declVec.clear();
+
+    for (llvm::ImmutableSet<const VarDecl *>::iterator si =
+          vals.liveDecls.begin(),
+          se = vals.liveDecls.end(); si != se; ++si) {
+      declVec.push_back(*si);
+    }
+
+    llvm::sort(declVec, [](const Decl *A, const Decl *B) {
+      return A->getBeginLoc() < B->getBeginLoc();
+    });
+
+    for (std::vector<const VarDecl*>::iterator di = declVec.begin(),
+         de = declVec.end(); di != de; ++di) {
+      llvm::errs() << " " << (*di)->getDeclName().getAsString()
+                   << " <";
+      (*di)->getLocation().print(llvm::errs(), M);
+      llvm::errs() << ">\n";
+    }
+  }
+  llvm::errs() << "\n";
+}
+
+void LiveVariables::dumpStmtLiveness(const SourceManager &M) {
+  getImpl(impl).dumpStmtLiveness(M);
+}
+
+void LiveVariablesImpl::dumpStmtLiveness(const SourceManager &M) {
+  // Don't iterate over blockEndsToLiveness directly because it's not sorted.
+  for (auto I : *analysisContext.getCFG()) {
+
+    llvm::errs() << "\n[ B" << I->getBlockID()
+                 << " (live statements at block exit) ]\n";
+    for (auto S : blocksEndToLiveness[I].liveStmts) {
+      llvm::errs() << "\n";
+      S->dump();
+    }
+    llvm::errs() << "\n";
+  }
+}
+
+const void *LiveVariables::getTag() { static int x; return &x; }
+const void *RelaxedLiveVariables::getTag() { static int x; return &x; }