Move the source-level CFG from libAST to libAnalysis.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@76092 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 0 insertions, 1924 deletions

diff --git a/lib/AST/CFG.cpp b/lib/AST/CFG.cpp
deleted file mode 100644
index 69852f5fea..0000000000
--- a/lib/AST/CFG.cpp
+++ /dev/null
@@ -1,1924 +0,0 @@
-//===--- CFG.cpp - Classes for representing and building CFGs----*- 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 the CFG and CFGBuilder classes for representing and
-//  building Control-Flow Graphs (CFGs) from ASTs.
-//
-//===----------------------------------------------------------------------===//
-
-#include "clang/AST/CFG.h"
-#include "clang/AST/StmtVisitor.h"
-#include "clang/AST/PrettyPrinter.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/Support/GraphWriter.h"
-#include "llvm/Support/Streams.h"
-#include "llvm/Support/Compiler.h"
-#include <llvm/Support/Allocator.h>
-#include <llvm/Support/Format.h>
-
-using namespace clang;
-
-namespace {
-
-// SaveAndRestore - A utility class that uses RIIA to save and restore
-//  the value of a variable.
-template<typename T>
-struct VISIBILITY_HIDDEN SaveAndRestore {
-  SaveAndRestore(T& x) : X(x), old_value(x) {}
-  ~SaveAndRestore() { X = old_value; }
-  T get() { return old_value; }
-
-  T& X;
-  T old_value;
-};
-  
-static SourceLocation GetEndLoc(Decl* D) {
-  if (VarDecl* VD = dyn_cast<VarDecl>(D))
-    if (Expr* Ex = VD->getInit())
-      return Ex->getSourceRange().getEnd();
-  
-  return D->getLocation();  
-}
-  
-/// CFGBuilder - This class implements CFG construction from an AST.
-///   The builder is stateful: an instance of the builder should be used to only
-///   construct a single CFG.
-///
-///   Example usage:
-///
-///     CFGBuilder builder;
-///     CFG* cfg = builder.BuildAST(stmt1);
-///
-///  CFG construction is done via a recursive walk of an AST.
-///  We actually parse the AST in reverse order so that the successor
-///  of a basic block is constructed prior to its predecessor.  This
-///  allows us to nicely capture implicit fall-throughs without extra
-///  basic blocks.
-///
-class VISIBILITY_HIDDEN CFGBuilder : public StmtVisitor<CFGBuilder,CFGBlock*> {    
-  CFG* cfg;
-  CFGBlock* Block;
-  CFGBlock* Succ;
-  CFGBlock* ContinueTargetBlock;
-  CFGBlock* BreakTargetBlock;
-  CFGBlock* SwitchTerminatedBlock;
-  CFGBlock* DefaultCaseBlock;
-  
-  // LabelMap records the mapping from Label expressions to their blocks.
-  typedef llvm::DenseMap<LabelStmt*,CFGBlock*> LabelMapTy;
-  LabelMapTy LabelMap;
-  
-  // A list of blocks that end with a "goto" that must be backpatched to
-  // their resolved targets upon completion of CFG construction.
-  typedef std::vector<CFGBlock*> BackpatchBlocksTy;
-  BackpatchBlocksTy BackpatchBlocks;
-  
-  // A list of labels whose address has been taken (for indirect gotos).
-  typedef llvm::SmallPtrSet<LabelStmt*,5> LabelSetTy;
-  LabelSetTy AddressTakenLabels;
-  
-public:  
-  explicit CFGBuilder() : cfg(NULL), Block(NULL), Succ(NULL),
-                          ContinueTargetBlock(NULL), BreakTargetBlock(NULL),
-                          SwitchTerminatedBlock(NULL), DefaultCaseBlock(NULL) {
-    // Create an empty CFG.
-    cfg = new CFG();                        
-  }
-  
-  ~CFGBuilder() { delete cfg; }
-  
-  // buildCFG - Used by external clients to construct the CFG.
-  CFG* buildCFG(Stmt* Statement);
-  
-  // Visitors to walk an AST and construct the CFG.  Called by
-  // buildCFG.  Do not call directly!
-  
-  CFGBlock* VisitBreakStmt(BreakStmt* B);
-  CFGBlock* VisitCaseStmt(CaseStmt* Terminator);
-  CFGBlock* VisitCompoundStmt(CompoundStmt* C);
-  CFGBlock* VisitContinueStmt(ContinueStmt* C);
-  CFGBlock* VisitDefaultStmt(DefaultStmt* D);
-  CFGBlock* VisitDoStmt(DoStmt* D);
-  CFGBlock* VisitForStmt(ForStmt* F);
-  CFGBlock* VisitGotoStmt(GotoStmt* G);
-  CFGBlock* VisitIfStmt(IfStmt* I);
-  CFGBlock* VisitIndirectGotoStmt(IndirectGotoStmt* I);
-  CFGBlock* VisitLabelStmt(LabelStmt* L);
-  CFGBlock* VisitNullStmt(NullStmt* Statement);
-  CFGBlock* VisitObjCForCollectionStmt(ObjCForCollectionStmt* S);
-  CFGBlock* VisitReturnStmt(ReturnStmt* R);
-  CFGBlock* VisitStmt(Stmt* Statement);
-  CFGBlock* VisitSwitchStmt(SwitchStmt* Terminator);
-  CFGBlock* VisitWhileStmt(WhileStmt* W);
-  
-  // FIXME: Add support for ObjC-specific control-flow structures.
-  
-  // NYS == Not Yet Supported
-  CFGBlock* NYS() {
-    badCFG = true;
-    return Block;
-  }
-  
-  CFGBlock* VisitObjCAtTryStmt(ObjCAtTryStmt* S);
-  CFGBlock* VisitObjCAtCatchStmt(ObjCAtCatchStmt* S) { 
-    // FIXME: For now we pretend that @catch and the code it contains
-    //  does not exit.
-    return Block;
-  }
-
-  // FIXME: This is not completely supported.  We basically @throw like
-  // a 'return'.
-  CFGBlock* VisitObjCAtThrowStmt(ObjCAtThrowStmt* S);
-
-  CFGBlock* VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt* S);
-  
-  // Blocks.
-  CFGBlock* VisitBlockExpr(BlockExpr* E) { return NYS(); }
-  CFGBlock* VisitBlockDeclRefExpr(BlockDeclRefExpr* E) { return NYS(); }  
-  
-private:
-  CFGBlock* createBlock(bool add_successor = true);
-  CFGBlock* addStmt(Stmt* Terminator);
-  CFGBlock* WalkAST(Stmt* Terminator, bool AlwaysAddStmt);
-  CFGBlock* WalkAST_VisitChildren(Stmt* Terminator);
-  CFGBlock* WalkAST_VisitDeclSubExpr(Decl* D);
-  CFGBlock* WalkAST_VisitStmtExpr(StmtExpr* Terminator);
-  bool FinishBlock(CFGBlock* B);
-  
-  bool badCFG;
-};
-  
-// FIXME: Add support for dependent-sized array types in C++?
-// Does it even make sense to build a CFG for an uninstantiated template?
-static VariableArrayType* FindVA(Type* t) {
-  while (ArrayType* vt = dyn_cast<ArrayType>(t)) {
-    if (VariableArrayType* vat = dyn_cast<VariableArrayType>(vt))
-      if (vat->getSizeExpr())
-        return vat;
-    
-    t = vt->getElementType().getTypePtr();
-  }
-  
-  return 0;
-}
-    
-/// BuildCFG - Constructs a CFG from an AST (a Stmt*).  The AST can
-///  represent an arbitrary statement.  Examples include a single expression
-///  or a function body (compound statement).  The ownership of the returned
-///  CFG is transferred to the caller.  If CFG construction fails, this method
-///  returns NULL.
-CFG* CFGBuilder::buildCFG(Stmt* Statement) {
-  assert (cfg);
-  if (!Statement) return NULL;
-
-  badCFG = false;
-  
-  // Create an empty block that will serve as the exit block for the CFG.
-  // Since this is the first block added to the CFG, it will be implicitly
-  // registered as the exit block.
-  Succ = createBlock();
-  assert (Succ == &cfg->getExit());
-  Block = NULL;  // the EXIT block is empty.  Create all other blocks lazily.
-  
-  // Visit the statements and create the CFG.
-  CFGBlock* B = Visit(Statement);
-  if (!B) B = Succ;
-  
-  if (B) {
-    // Finalize the last constructed block.  This usually involves
-    // reversing the order of the statements in the block.
-    if (Block) FinishBlock(B);
-    
-    // Backpatch the gotos whose label -> block mappings we didn't know
-    // when we encountered them.
-    for (BackpatchBlocksTy::iterator I = BackpatchBlocks.begin(), 
-         E = BackpatchBlocks.end(); I != E; ++I ) {
-     
-      CFGBlock* B = *I;
-      GotoStmt* G = cast<GotoStmt>(B->getTerminator());
-      LabelMapTy::iterator LI = LabelMap.find(G->getLabel());
-
-      // If there is no target for the goto, then we are looking at an
-      // incomplete AST.  Handle this by not registering a successor.
-      if (LI == LabelMap.end()) continue;
-      
-      B->addSuccessor(LI->second);                   
-    }
-    
-    // Add successors to the Indirect Goto Dispatch block (if we have one).
-    if (CFGBlock* B = cfg->getIndirectGotoBlock())
-      for (LabelSetTy::iterator I = AddressTakenLabels.begin(),
-           E = AddressTakenLabels.end(); I != E; ++I ) {
-
-        // Lookup the target block.
-        LabelMapTy::iterator LI = LabelMap.find(*I);
-
-        // If there is no target block that contains label, then we are looking
-        // at an incomplete AST.  Handle this by not registering a successor.
-        if (LI == LabelMap.end()) continue;
-        
-        B->addSuccessor(LI->second);           
-      }
-                                                          
-    Succ = B;
-  }
-  
-  // Create an empty entry block that has no predecessors.    
-  cfg->setEntry(createBlock());
-    
-  if (badCFG) {
-    delete cfg;
-    cfg = NULL;
-    return NULL;
-  }
-    
-  // NULL out cfg so that repeated calls to the builder will fail and that
-  // the ownership of the constructed CFG is passed to the caller.
-  CFG* t = cfg;
-  cfg = NULL;
-  return t;
-}
-  
-/// createBlock - Used to lazily create blocks that are connected
-///  to the current (global) succcessor.
-CFGBlock* CFGBuilder::createBlock(bool add_successor) { 
-  CFGBlock* B = cfg->createBlock();
-  if (add_successor && Succ) B->addSuccessor(Succ);
-  return B;
-}
-  
-/// FinishBlock - When the last statement has been added to the block,
-///  we must reverse the statements because they have been inserted
-///  in reverse order.
-bool CFGBuilder::FinishBlock(CFGBlock* B) {
-  if (badCFG)
-    return false;
-
-  assert (B);
-  B->reverseStmts();
-  return true;
-}
-
-/// addStmt - Used to add statements/expressions to the current CFGBlock 
-///  "Block".  This method calls WalkAST on the passed statement to see if it
-///  contains any short-circuit expressions.  If so, it recursively creates
-///  the necessary blocks for such expressions.  It returns the "topmost" block
-///  of the created blocks, or the original value of "Block" when this method
-///  was called if no additional blocks are created.
-CFGBlock* CFGBuilder::addStmt(Stmt* Terminator) {
-  if (!Block) Block = createBlock();
-  return WalkAST(Terminator,true);
-}
-
-/// WalkAST - Used by addStmt to walk the subtree of a statement and
-///   add extra blocks for ternary operators, &&, and ||.  We also
-///   process "," and DeclStmts (which may contain nested control-flow).
-CFGBlock* CFGBuilder::WalkAST(Stmt* Terminator, bool AlwaysAddStmt = false) {    
-  switch (Terminator->getStmtClass()) {
-    case Stmt::ConditionalOperatorClass: {
-      ConditionalOperator* C = cast<ConditionalOperator>(Terminator);
-
-      // Create the confluence block that will "merge" the results
-      // of the ternary expression.
-      CFGBlock* ConfluenceBlock = (Block) ? Block : createBlock();  
-      ConfluenceBlock->appendStmt(C);
-      if (!FinishBlock(ConfluenceBlock))
-        return 0;
-
-      // Create a block for the LHS expression if there is an LHS expression.
-      // A GCC extension allows LHS to be NULL, causing the condition to
-      // be the value that is returned instead.
-      //  e.g: x ?: y is shorthand for: x ? x : y;
-      Succ = ConfluenceBlock;
-      Block = NULL;
-      CFGBlock* LHSBlock = NULL;
-      if (C->getLHS()) {
-        LHSBlock = Visit(C->getLHS());
-        if (!FinishBlock(LHSBlock))
-          return 0;
-        Block = NULL;        
-      }
-      
-      // Create the block for the RHS expression.
-      Succ = ConfluenceBlock;
-      CFGBlock* RHSBlock = Visit(C->getRHS());
-      if (!FinishBlock(RHSBlock))
-        return 0;
-
-      // Create the block that will contain the condition.
-      Block = createBlock(false);
-      
-      if (LHSBlock)
-        Block->addSuccessor(LHSBlock);
-      else {
-        // If we have no LHS expression, add the ConfluenceBlock as a direct
-        // successor for the block containing the condition.  Moreover,
-        // we need to reverse the order of the predecessors in the
-        // ConfluenceBlock because the RHSBlock will have been added to
-        // the succcessors already, and we want the first predecessor to the
-        // the block containing the expression for the case when the ternary
-        // expression evaluates to true.
-        Block->addSuccessor(ConfluenceBlock);
-        assert (ConfluenceBlock->pred_size() == 2);
-        std::reverse(ConfluenceBlock->pred_begin(), 
-                     ConfluenceBlock->pred_end());
-      }
-      
-      Block->addSuccessor(RHSBlock);
-      
-      Block->setTerminator(C);
-      return addStmt(C->getCond());
-    }
-    
-    case Stmt::ChooseExprClass: {
-      ChooseExpr* C = cast<ChooseExpr>(Terminator);      
-      
-      CFGBlock* ConfluenceBlock = Block ? Block : createBlock();  
-      ConfluenceBlock->appendStmt(C);
-      if (!FinishBlock(ConfluenceBlock))
-        return 0;
-      
-      Succ = ConfluenceBlock;
-      Block = NULL;
-      CFGBlock* LHSBlock = Visit(C->getLHS());
-      if (!FinishBlock(LHSBlock))
-        return 0;
-
-      Succ = ConfluenceBlock;
-      Block = NULL;
-      CFGBlock* RHSBlock = Visit(C->getRHS());
-      if (!FinishBlock(RHSBlock))
-        return 0;
-      
-      Block = createBlock(false);
-      Block->addSuccessor(LHSBlock);
-      Block->addSuccessor(RHSBlock);
-      Block->setTerminator(C);
-      return addStmt(C->getCond());
-    }
-
-    case Stmt::DeclStmtClass: {
-      DeclStmt *DS = cast<DeclStmt>(Terminator);      
-      if (DS->isSingleDecl()) {      
-        Block->appendStmt(Terminator);
-        return WalkAST_VisitDeclSubExpr(DS->getSingleDecl());
-      }
-      
-      CFGBlock* B = 0;
-
-      // FIXME: Add a reverse iterator for DeclStmt to avoid this
-      // extra copy.
-      typedef llvm::SmallVector<Decl*,10> BufTy;
-      BufTy Buf(DS->decl_begin(), DS->decl_end());
-      
-      for (BufTy::reverse_iterator I=Buf.rbegin(), E=Buf.rend(); I!=E; ++I) {
-        // Get the alignment of the new DeclStmt, padding out to >=8 bytes.
-        unsigned A = llvm::AlignOf<DeclStmt>::Alignment < 8
-                     ? 8 : llvm::AlignOf<DeclStmt>::Alignment;
-        
-        // Allocate the DeclStmt using the BumpPtrAllocator.  It will
-        // get automatically freed with the CFG. 
-        DeclGroupRef DG(*I);
-        Decl* D = *I;
-        void* Mem = cfg->getAllocator().Allocate(sizeof(DeclStmt), A);
-        
-        DeclStmt* DS = new (Mem) DeclStmt(DG, D->getLocation(), GetEndLoc(D));
-        
-        // Append the fake DeclStmt to block.
-        Block->appendStmt(DS);
-        B = WalkAST_VisitDeclSubExpr(D);
-      }
-      return B;
-    }
-
-    case Stmt::AddrLabelExprClass: {
-      AddrLabelExpr* A = cast<AddrLabelExpr>(Terminator);
-      AddressTakenLabels.insert(A->getLabel());
-      
-      if (AlwaysAddStmt) Block->appendStmt(Terminator);
-      return Block;
-    }
-    
-    case Stmt::StmtExprClass:
-      return WalkAST_VisitStmtExpr(cast<StmtExpr>(Terminator));
-
-    case Stmt::SizeOfAlignOfExprClass: {
-      SizeOfAlignOfExpr* E = cast<SizeOfAlignOfExpr>(Terminator);
-
-      // VLA types have expressions that must be evaluated.
-      if (E->isArgumentType()) {
-        for (VariableArrayType* VA = FindVA(E->getArgumentType().getTypePtr());
-             VA != 0; VA = FindVA(VA->getElementType().getTypePtr()))
-          addStmt(VA->getSizeExpr());
-      }
-      // Expressions in sizeof/alignof are not evaluated and thus have no
-      // control flow.
-      else
-        Block->appendStmt(Terminator);
-
-      return Block;
-    }
-      
-    case Stmt::BinaryOperatorClass: {
-      BinaryOperator* B = cast<BinaryOperator>(Terminator);
-
-      if (B->isLogicalOp()) { // && or ||
-        CFGBlock* ConfluenceBlock = (Block) ? Block : createBlock();  
-        ConfluenceBlock->appendStmt(B);
-        if (!FinishBlock(ConfluenceBlock))
-          return 0;
-
-        // create the block evaluating the LHS
-        CFGBlock* LHSBlock = createBlock(false);
-        LHSBlock->setTerminator(B);
-        
-        // create the block evaluating the RHS
-        Succ = ConfluenceBlock;
-        Block = NULL;
-        CFGBlock* RHSBlock = Visit(B->getRHS());
-        if (!FinishBlock(RHSBlock))
-          return 0;
-
-        // Now link the LHSBlock with RHSBlock.
-        if (B->getOpcode() == BinaryOperator::LOr) {
-          LHSBlock->addSuccessor(ConfluenceBlock);
-          LHSBlock->addSuccessor(RHSBlock);
-        }
-        else {
-          assert (B->getOpcode() == BinaryOperator::LAnd);
-          LHSBlock->addSuccessor(RHSBlock);
-          LHSBlock->addSuccessor(ConfluenceBlock);
-        }
-        
-        // Generate the blocks for evaluating the LHS.
-        Block = LHSBlock;
-        return addStmt(B->getLHS());                                    
-      }
-      else if (B->getOpcode() == BinaryOperator::Comma) { // ,
-        Block->appendStmt(B);
-        addStmt(B->getRHS());
-        return addStmt(B->getLHS());
-      }
-      
-      break;
-    }
-    
-    // Blocks: No support for blocks ... yet
-    case Stmt::BlockExprClass:
-    case Stmt::BlockDeclRefExprClass:
-      return NYS();
-      
-    case Stmt::ParenExprClass:
-      return WalkAST(cast<ParenExpr>(Terminator)->getSubExpr(), AlwaysAddStmt);
-    
-    default:
-      break;
-  };
-      
-  if (AlwaysAddStmt) Block->appendStmt(Terminator);
-  return WalkAST_VisitChildren(Terminator);
-}
-  
-/// WalkAST_VisitDeclSubExpr - Utility method to add block-level expressions
-///  for initializers in Decls.
-CFGBlock* CFGBuilder::WalkAST_VisitDeclSubExpr(Decl* D) {
-  VarDecl* VD = dyn_cast<VarDecl>(D);
-
-  if (!VD)
-    return Block;
-  
-  Expr* Init = VD->getInit();
-  
-  if (Init) {
-    // Optimization: Don't create separate block-level statements for literals.
-    switch (Init->getStmtClass()) {
-      case Stmt::IntegerLiteralClass:
-      case Stmt::CharacterLiteralClass:
-      case Stmt::StringLiteralClass:
-        break;
-      default:
-        Block = addStmt(Init);
-    }
-  }
-    
-  // If the type of VD is a VLA, then we must process its size expressions.
-  for (VariableArrayType* VA = FindVA(VD->getType().getTypePtr()); VA != 0;
-       VA = FindVA(VA->getElementType().getTypePtr()))
-    Block = addStmt(VA->getSizeExpr());  
-  
-  return Block;
-}
-
-/// WalkAST_VisitChildren - Utility method to call WalkAST on the
-///  children of a Stmt.
-CFGBlock* CFGBuilder::WalkAST_VisitChildren(Stmt* Terminator) {
-  CFGBlock* B = Block;
-  for (Stmt::child_iterator I = Terminator->child_begin(),
-         E = Terminator->child_end();
-       I != E; ++I)
-    if (*I) B = WalkAST(*I);
-  
-  return B;
-}
-
-/// WalkAST_VisitStmtExpr - Utility method to handle (nested) statement
-///  expressions (a GCC extension).
-CFGBlock* CFGBuilder::WalkAST_VisitStmtExpr(StmtExpr* Terminator) {
-  Block->appendStmt(Terminator);
-  return VisitCompoundStmt(Terminator->getSubStmt());  
-}
-
-/// VisitStmt - Handle statements with no branching control flow.
-CFGBlock* CFGBuilder::VisitStmt(Stmt* Statement) {
-  // We cannot assume that we are in the middle of a basic block, since
-  // the CFG might only be constructed for this single statement.  If
-  // we have no current basic block, just create one lazily.
-  if (!Block) Block = createBlock();
-  
-  // Simply add the statement to the current block.  We actually
-  // insert statements in reverse order; this order is reversed later
-  // when processing the containing element in the AST.
-  addStmt(Statement);
-
-  return Block;
-}
-
-CFGBlock* CFGBuilder::VisitNullStmt(NullStmt* Statement) {
-  return Block;
-}
-
-CFGBlock* CFGBuilder::VisitCompoundStmt(CompoundStmt* C) {
-  
-  CFGBlock* LastBlock = Block;
-
-  for (CompoundStmt::reverse_body_iterator I=C->body_rbegin(), E=C->body_rend();
-                                                               I != E; ++I ) {
-    LastBlock = Visit(*I);
-  }
-
-  return LastBlock;
-}
-
-CFGBlock* CFGBuilder::VisitIfStmt(IfStmt* I) {
-  // We may see an if statement in the middle of a basic block, or
-  // it may be the first statement we are processing.  In either case,
-  // we create a new basic block.  First, we create the blocks for
-  // the then...else statements, and then we create the block containing
-  // the if statement.  If we were in the middle of a block, we
-  // stop processing that block and reverse its statements.  That block
-  // is then the implicit successor for the "then" and "else" clauses.
-  
-  // The block we were proccessing is now finished.  Make it the
-  // successor block.
-  if (Block) { 
-    Succ = Block;
-    if (!FinishBlock(Block))
-      return 0;
-  }
-  
-  // Process the false branch.  NULL out Block so that the recursive
-  // call to Visit will create a new basic block.
-  // Null out Block so that all successor
-  CFGBlock* ElseBlock = Succ;
-  
-  if (Stmt* Else = I->getElse()) {
-    SaveAndRestore<CFGBlock*> sv(Succ);
-    
-    // NULL out Block so that the recursive call to Visit will
-    // create a new basic block.          
-    Block = NULL;
-    ElseBlock = Visit(Else);
-              
-    if (!ElseBlock) // Can occur when the Else body has all NullStmts.
-      ElseBlock = sv.get();
-    else if (Block) {
-      if (!FinishBlock(ElseBlock))
-        return 0;
-    }
-  }
-  
-  // Process the true branch.  NULL out Block so that the recursive
-  // call to Visit will create a new basic block.
-  // Null out Block so that all successor
-  CFGBlock* ThenBlock;
-  {
-    Stmt* Then = I->getThen();
-    assert (Then);
-    SaveAndRestore<CFGBlock*> sv(Succ);
-    Block = NULL;        
-    ThenBlock = Visit(Then);
-    
-    if (!ThenBlock) {
-      // We can reach here if the "then" body has all NullStmts.
-      // Create an empty block so we can distinguish between true and false
-      // branches in path-sensitive analyses.
-      ThenBlock = createBlock(false);
-      ThenBlock->addSuccessor(sv.get());
-    }
-    else if (Block) {
-      if (!FinishBlock(ThenBlock))
-        return 0;
-    }        
-  }
-
-  // Now create a new block containing the if statement.        
-  Block = createBlock(false);
-  
-  // Set the terminator of the new block to the If statement.
-  Block->setTerminator(I);
-  
-  // Now add the successors.
-  Block->addSuccessor(ThenBlock);
-  Block->addSuccessor(ElseBlock);
-  
-  // Add the condition as the last statement in the new block.  This
-  // may create new blocks as the condition may contain control-flow.  Any
-  // newly created blocks will be pointed to be "Block".
-  return addStmt(I->getCond()->IgnoreParens());
-}
-  
-    
-CFGBlock* CFGBuilder::VisitReturnStmt(ReturnStmt* R) {
-  // If we were in the middle of a block we stop processing that block
-  // and reverse its statements.
-  //
-  // NOTE: If a "return" appears in the middle of a block, this means
-  //       that the code afterwards is DEAD (unreachable).  We still
-  //       keep a basic block for that code; a simple "mark-and-sweep"
-  //       from the entry block will be able to report such dead
-  //       blocks.
-  if (Block) FinishBlock(Block);
-
-  // Create the new block.
-  Block = createBlock(false);
-  
-  // The Exit block is the only successor.
-  Block->addSuccessor(&cfg->getExit());
-    
-  // Add the return statement to the block.  This may create new blocks
-  // if R contains control-flow (short-circuit operations).
-  return addStmt(R);
-}
-
-CFGBlock* CFGBuilder::VisitLabelStmt(LabelStmt* L) {
-  // Get the block of the labeled statement.  Add it to our map.
-  Visit(L->getSubStmt());
-  CFGBlock* LabelBlock = Block;
-  
-  if (!LabelBlock)            // This can happen when the body is empty, i.e.
-    LabelBlock=createBlock(); // scopes that only contains NullStmts.
-  
-  assert (LabelMap.find(L) == LabelMap.end() && "label already in map");
-  LabelMap[ L ] = LabelBlock;
-  
-  // Labels partition blocks, so this is the end of the basic block
-  // we were processing (L is the block's label).  Because this is
-  // label (and we have already processed the substatement) there is no
-  // extra control-flow to worry about.
-  LabelBlock->setLabel(L);
-  if (!FinishBlock(LabelBlock))
-    return 0;
-  
-  // We set Block to NULL to allow lazy creation of a new block
-  // (if necessary);
-  Block = NULL;
-  
-  // This block is now the implicit successor of other blocks.
-  Succ = LabelBlock;
-  
-  return LabelBlock;
-}
-
-CFGBlock* CFGBuilder::VisitGotoStmt(GotoStmt* G) {
-  // Goto is a control-flow statement.  Thus we stop processing the
-  // current block and create a new one.
-  if (Block) FinishBlock(Block);
-  Block = createBlock(false);
-  Block->setTerminator(G);
-  
-  // If we already know the mapping to the label block add the
-  // successor now.
-  LabelMapTy::iterator I = LabelMap.find(G->getLabel());
-  
-  if (I == LabelMap.end())
-    // We will need to backpatch this block later.
-    BackpatchBlocks.push_back(Block);
-  else
-    Block->addSuccessor(I->second);
-
-  return Block;            
-}
-
-CFGBlock* CFGBuilder::VisitForStmt(ForStmt* F) {
-  // "for" is a control-flow statement.  Thus we stop processing the
-  // current block.
-  
-  CFGBlock* LoopSuccessor = NULL;
-  
-  if (Block) {
-    if (!FinishBlock(Block))
-      return 0;
-    LoopSuccessor = Block;
-  }
-  else LoopSuccessor = Succ;
-  
-  // Because of short-circuit evaluation, the condition of the loop
-  // can span multiple basic blocks.  Thus we need the "Entry" and "Exit"
-  // blocks that evaluate the condition.
-  CFGBlock* ExitConditionBlock = createBlock(false);
-  CFGBlock* EntryConditionBlock = ExitConditionBlock;
-  
-  // Set the terminator for the "exit" condition block.
-  ExitConditionBlock->setTerminator(F);  
-  
-  // Now add the actual condition to the condition block.  Because the
-  // condition itself may contain control-flow, new blocks may be created.
-  if (Stmt* C = F->getCond()) {
-    Block = ExitConditionBlock;
-    EntryConditionBlock = addStmt(C);
-    if (Block) {
-      if (!FinishBlock(EntryConditionBlock))
-        return 0;
-    }
-  }
-
-  // The condition block is the implicit successor for the loop body as
-  // well as any code above the loop.
-  Succ = EntryConditionBlock;
-  
-  // Now create the loop body.
-  {
-    assert (F->getBody());
-    
-    // Save the current values for Block, Succ, and continue and break targets
-    SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ),
-    save_continue(ContinueTargetBlock),
-    save_break(BreakTargetBlock);      
- 
-    // Create a new block to contain the (bottom) of the loop body.
-    Block = NULL;
-    
-    if (Stmt* I = F->getInc()) {
-      // Generate increment code in its own basic block.  This is the target
-      // of continue statements.
-      Succ = Visit(I);
-    }
-    else {
-      // No increment code.  Create a special, empty, block that is used as
-      // the target block for "looping back" to the start of the loop.
-      assert(Succ == EntryConditionBlock);
-      Succ = createBlock();
-    }
-    
-    // Finish up the increment (or empty) block if it hasn't been already.
-    if (Block) {
-      assert(Block == Succ);
-      if (!FinishBlock(Block))
-        return 0;
-      Block = 0;
-    }
-    
-    ContinueTargetBlock = Succ;
-    
-    // The starting block for the loop increment is the block that should
-    // represent the 'loop target' for looping back to the start of the loop.
-    ContinueTargetBlock->setLoopTarget(F);
-
-    // All breaks should go to the code following the loop.
-    BreakTargetBlock = LoopSuccessor;    
-    
-    // Now populate the body block, and in the process create new blocks
-    // as we walk the body of the loop.
-    CFGBlock* BodyBlock = Visit(F->getBody());      
-
-    if (!BodyBlock)
-      BodyBlock = EntryConditionBlock; // can happen for "for (...;...; ) ;"
-    else if (Block) {
-      if (!FinishBlock(BodyBlock))
-        return 0;
-    }      
-    
-    // This new body block is a successor to our "exit" condition block.
-    ExitConditionBlock->addSuccessor(BodyBlock);
-  }
-  
-  // Link up the condition block with the code that follows the loop.
-  // (the false branch).
-  ExitConditionBlock->addSuccessor(LoopSuccessor);
-  
-  // If the loop contains initialization, create a new block for those
-  // statements.  This block can also contain statements that precede
-  // the loop.
-  if (Stmt* I = F->getInit()) {
-    Block = createBlock();
-    return addStmt(I);
-  }
-  else {
-    // There is no loop initialization.   We are thus basically a while 
-    // loop.  NULL out Block to force lazy block construction.
-    Block = NULL;
-    Succ = EntryConditionBlock;
-    return EntryConditionBlock;
-  }
-}
-
-CFGBlock* CFGBuilder::VisitObjCForCollectionStmt(ObjCForCollectionStmt* S) {
-  // Objective-C fast enumeration 'for' statements:
-  //  http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC
-  //
-  //  for ( Type newVariable in collection_expression ) { statements }
-  //
-  //  becomes:
-  //
-  //   prologue:
-  //     1. collection_expression
-  //     T. jump to loop_entry
-  //   loop_entry:
-  //     1. side-effects of element expression
-  //     1. ObjCForCollectionStmt [performs binding to newVariable]
-  //     T. ObjCForCollectionStmt  TB, FB  [jumps to TB if newVariable != nil]
-  //   TB:
-  //     statements
-  //     T. jump to loop_entry
-  //   FB:
-  //     what comes after
-  //
-  //  and
-  //
-  //  Type existingItem;
-  //  for ( existingItem in expression ) { statements }
-  //
-  //  becomes:
-  //
-  //   the same with newVariable replaced with existingItem; the binding
-  //   works the same except that for one ObjCForCollectionStmt::getElement()
-  //   returns a DeclStmt and the other returns a DeclRefExpr.
-  //
-  
-  CFGBlock* LoopSuccessor = 0;
-  
-  if (Block) {
-    if (!FinishBlock(Block))
-      return 0;
-    LoopSuccessor = Block;
-    Block = 0;
-  }
-  else LoopSuccessor = Succ;
-  
-  // Build the condition blocks.
-  CFGBlock* ExitConditionBlock = createBlock(false);
-  CFGBlock* EntryConditionBlock = ExitConditionBlock;
-  
-  // Set the terminator for the "exit" condition block.
-  ExitConditionBlock->setTerminator(S);  
-  
-  // The last statement in the block should be the ObjCForCollectionStmt,
-  // which performs the actual binding to 'element' and determines if there
-  // are any more items in the collection.
-  ExitConditionBlock->appendStmt(S);
-  Block = ExitConditionBlock;
-  
-  // Walk the 'element' expression to see if there are any side-effects.  We
-  // generate new blocks as necesary.  We DON'T add the statement by default
-  // to the CFG unless it contains control-flow.
-  EntryConditionBlock = WalkAST(S->getElement(), false);
-  if (Block) { 
-    if (!FinishBlock(EntryConditionBlock))
-      return 0;
-    Block = 0;
-  }
-  
-  // The condition block is the implicit successor for the loop body as
-  // well as any code above the loop.
-  Succ = EntryConditionBlock;
-  
-  // Now create the true branch.
-  { 
-    // Save the current values for Succ, continue and break targets.
-    SaveAndRestore<CFGBlock*> save_Succ(Succ),
-      save_continue(ContinueTargetBlock), save_break(BreakTargetBlock); 
-    
-    BreakTargetBlock = LoopSuccessor;
-    ContinueTargetBlock = EntryConditionBlock;  
-    
-    CFGBlock* BodyBlock = Visit(S->getBody());
-    
-    if (!BodyBlock)
-      BodyBlock = EntryConditionBlock; // can happen for "for (X in Y) ;"
-    else if (Block) {
-      if (!FinishBlock(BodyBlock))
-        return 0;
-    }
-                  
-    // This new body block is a successor to our "exit" condition block.
-    ExitConditionBlock->addSuccessor(BodyBlock);
-  }
-  
-  // Link up the condition block with the code that follows the loop.
-  // (the false branch).
-  ExitConditionBlock->addSuccessor(LoopSuccessor);
-
-  // Now create a prologue block to contain the collection expression.
-  Block = createBlock();
-  return addStmt(S->getCollection());
-}    
-  
-CFGBlock* CFGBuilder::VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt* S) {
-  // FIXME: Add locking 'primitives' to CFG for @synchronized.
-  
-  // Inline the body.
-  CFGBlock *SyncBlock = Visit(S->getSynchBody());
-  
-  // The sync body starts its own basic block.  This makes it a little easier
-  // for diagnostic clients.
-  if (SyncBlock) {
-    if (!FinishBlock(SyncBlock))
-      return 0;
-    
-    Block = 0;
-  }
-    
-  Succ = SyncBlock;
-  
-  // Inline the sync expression.
-  return Visit(S->getSynchExpr());
-}
-  
-CFGBlock* CFGBuilder::VisitObjCAtTryStmt(ObjCAtTryStmt* S) {
-  return NYS();
-}
-
-CFGBlock* CFGBuilder::VisitWhileStmt(WhileStmt* W) {
-  // "while" is a control-flow statement.  Thus we stop processing the
-  // current block.
-  
-  CFGBlock* LoopSuccessor = NULL;
-  
-  if (Block) {
-    if (!FinishBlock(Block))
-      return 0;
-    LoopSuccessor = Block;
-  }
-  else LoopSuccessor = Succ;
-            
-  // Because of short-circuit evaluation, the condition of the loop
-  // can span multiple basic blocks.  Thus we need the "Entry" and "Exit"
-  // blocks that evaluate the condition.
-  CFGBlock* ExitConditionBlock = createBlock(false);
-  CFGBlock* EntryConditionBlock = ExitConditionBlock;
-  
-  // Set the terminator for the "exit" condition block.
-  ExitConditionBlock->setTerminator(W);
-  
-  // Now add the actual condition to the condition block.  Because the
-  // condition itself may contain control-flow, new blocks may be created.
-  // Thus we update "Succ" after adding the condition.
-  if (Stmt* C = W->getCond()) {
-    Block = ExitConditionBlock;
-    EntryConditionBlock = addStmt(C);
-    assert(Block == EntryConditionBlock);
-    if (Block) {
-      if (!FinishBlock(EntryConditionBlock))
-        return 0;
-    }
-  }
-  
-  // The condition block is the implicit successor for the loop body as
-  // well as any code above the loop.
-  Succ = EntryConditionBlock;
-  
-  // Process the loop body.
-  {
-    assert(W->getBody());
-
-    // Save the current values for Block, Succ, and continue and break targets
-    SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ),
-                              save_continue(ContinueTargetBlock),
-                              save_break(BreakTargetBlock);
-
-    // Create an empty block to represent the transition block for looping
-    // back to the head of the loop.
-    Block = 0;
-    assert(Succ == EntryConditionBlock);
-    Succ = createBlock();
-    Succ->setLoopTarget(W);
-    ContinueTargetBlock = Succ;    
-    
-    // All breaks should go to the code following the loop.
-    BreakTargetBlock = LoopSuccessor;
-    
-    // NULL out Block to force lazy instantiation of blocks for the body.
-    Block = NULL;
-    
-    // Create the body.  The returned block is the entry to the loop body.
-    CFGBlock* BodyBlock = Visit(W->getBody());
-    
-    if (!BodyBlock)
-      BodyBlock = EntryConditionBlock; // can happen for "while(...) ;"
-    else if (Block) {
-      if (!FinishBlock(BodyBlock))
-        return 0;
-    }
-    
-    // Add the loop body entry as a successor to the condition.
-    ExitConditionBlock->addSuccessor(BodyBlock);
-  }
-  
-  // Link up the condition block with the code that follows the loop.
-  // (the false branch).
-  ExitConditionBlock->addSuccessor(LoopSuccessor);
-