CFG.h revision fdf6a279c9a75c778eba382d9a156697092982a1 
1//===--- CFG.h - Classes for representing and building CFGs------*- 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 the CFG and CFGBuilder classes for representing and
11//  building Control-Flow Graphs (CFGs) from ASTs.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_CLANG_CFG_H
16#define LLVM_CLANG_CFG_H
17
18#include "clang/AST/Stmt.h"
19#include "clang/Analysis/Support/BumpVector.h"
20#include "clang/Basic/SourceLocation.h"
21#include "llvm/ADT/DenseMap.h"
22#include "llvm/ADT/GraphTraits.h"
23#include "llvm/ADT/Optional.h"
24#include "llvm/ADT/OwningPtr.h"
25#include "llvm/ADT/PointerIntPair.h"
26#include "llvm/Support/Allocator.h"
27#include "llvm/Support/Casting.h"
28#include <bitset>
29#include <cassert>
30#include <iterator>
31
32namespace clang {
33  class CXXDestructorDecl;
34  class Decl;
35  class Stmt;
36  class Expr;
37  class FieldDecl;
38  class VarDecl;
39  class CXXCtorInitializer;
40  class CXXBaseSpecifier;
41  class CXXBindTemporaryExpr;
42  class CFG;
43  class PrinterHelper;
44  class LangOptions;
45  class ASTContext;
46
47/// CFGElement - Represents a top-level expression in a basic block.
48class CFGElement {
49public:
50  enum Kind {
51    // main kind
52    Invalid,
53    Statement,
54    Initializer,
55    // dtor kind
56    AutomaticObjectDtor,
57    BaseDtor,
58    MemberDtor,
59    TemporaryDtor,
60    DTOR_BEGIN = AutomaticObjectDtor,
61    DTOR_END = TemporaryDtor
62  };
63
64protected:
65  // The int bits are used to mark the kind.
66  llvm::PointerIntPair<void *, 2> Data1;
67  llvm::PointerIntPair<void *, 2> Data2;
68
69  CFGElement(Kind kind, const void *Ptr1, const void *Ptr2 = 0)
70    : Data1(const_cast<void*>(Ptr1), ((unsigned) kind) & 0x3),
71      Data2(const_cast<void*>(Ptr2), (((unsigned) kind) >> 2) & 0x3) {}
72
73public:
74  CFGElement() {}
75
76  /// \brief Convert to the specified CFGElement type, asserting that this
77  /// CFGElement is of the desired type.
78  template<typename T>
79  T castAs() const {
80    assert(T::isKind(*this));
81    T t;
82    CFGElement& e = t;
83    e = *this;
84    return t;
85  }
86
87  /// \brief Convert to the specified CFGElement type, returning an invalid
88  /// CFGElement if this CFGElement is not of the desired type.
89  template<typename T>
90  T getAs() const {
91    if (!T::isKind(*this))
92      return T();
93    T t;
94    CFGElement& e = t;
95    e = *this;
96    return t;
97  }
98
99  Kind getKind() const {
100    unsigned x = Data2.getInt();
101    x <<= 2;
102    x |= Data1.getInt();
103    return (Kind) x;
104  }
105
106  bool isValid() const { return getKind() != Invalid; }
107
108  operator bool() const { return isValid(); }
109};
110
111class CFGStmt : public CFGElement {
112public:
113  CFGStmt(Stmt *S) : CFGElement(Statement, S) {}
114
115  const Stmt *getStmt() const {
116    return static_cast<const Stmt *>(Data1.getPointer());
117  }
118
119private:
120  friend class CFGElement;
121  CFGStmt() {}
122  static bool isKind(const CFGElement &E) {
123    return E.getKind() == Statement;
124  }
125};
126
127/// CFGInitializer - Represents C++ base or member initializer from
128/// constructor's initialization list.
129class CFGInitializer : public CFGElement {
130public:
131  CFGInitializer(CXXCtorInitializer *initializer)
132      : CFGElement(Initializer, initializer) {}
133
134  CXXCtorInitializer* getInitializer() const {
135    return static_cast<CXXCtorInitializer*>(Data1.getPointer());
136  }
137
138private:
139  friend class CFGElement;
140  CFGInitializer() {}
141  static bool isKind(const CFGElement &E) {
142    return E.getKind() == Initializer;
143  }
144};
145
146/// CFGImplicitDtor - Represents C++ object destructor implicitly generated
147/// by compiler on various occasions.
148class CFGImplicitDtor : public CFGElement {
149protected:
150  CFGImplicitDtor() {}
151  CFGImplicitDtor(Kind kind, const void *data1, const void *data2 = 0)
152    : CFGElement(kind, data1, data2) {
153    assert(kind >= DTOR_BEGIN && kind <= DTOR_END);
154  }
155
156public:
157  const CXXDestructorDecl *getDestructorDecl(ASTContext &astContext) const;
158  bool isNoReturn(ASTContext &astContext) const;
159
160private:
161  friend class CFGElement;
162  static bool isKind(const CFGElement &E) {
163    Kind kind = E.getKind();
164    return kind >= DTOR_BEGIN && kind <= DTOR_END;
165  }
166};
167
168/// CFGAutomaticObjDtor - Represents C++ object destructor implicitly generated
169/// for automatic object or temporary bound to const reference at the point
170/// of leaving its local scope.
171class CFGAutomaticObjDtor: public CFGImplicitDtor {
172public:
173  CFGAutomaticObjDtor(const VarDecl *var, const Stmt *stmt)
174      : CFGImplicitDtor(AutomaticObjectDtor, var, stmt) {}
175
176  const VarDecl *getVarDecl() const {
177    return static_cast<VarDecl*>(Data1.getPointer());
178  }
179
180  // Get statement end of which triggered the destructor call.
181  const Stmt *getTriggerStmt() const {
182    return static_cast<Stmt*>(Data2.getPointer());
183  }
184
185private:
186  friend class CFGElement;
187  CFGAutomaticObjDtor() {}
188  static bool isKind(const CFGElement &elem) {
189    return elem.getKind() == AutomaticObjectDtor;
190  }
191};
192
193/// CFGBaseDtor - Represents C++ object destructor implicitly generated for
194/// base object in destructor.
195class CFGBaseDtor : public CFGImplicitDtor {
196public:
197  CFGBaseDtor(const CXXBaseSpecifier *base)
198      : CFGImplicitDtor(BaseDtor, base) {}
199
200  const CXXBaseSpecifier *getBaseSpecifier() const {
201    return static_cast<const CXXBaseSpecifier*>(Data1.getPointer());
202  }
203
204private:
205  friend class CFGElement;
206  CFGBaseDtor() {}
207  static bool isKind(const CFGElement &E) {
208    return E.getKind() == BaseDtor;
209  }
210};
211
212/// CFGMemberDtor - Represents C++ object destructor implicitly generated for
213/// member object in destructor.
214class CFGMemberDtor : public CFGImplicitDtor {
215public:
216  CFGMemberDtor(const FieldDecl *field)
217      : CFGImplicitDtor(MemberDtor, field, 0) {}
218
219  const FieldDecl *getFieldDecl() const {
220    return static_cast<const FieldDecl*>(Data1.getPointer());
221  }
222
223private:
224  friend class CFGElement;
225  CFGMemberDtor() {}
226  static bool isKind(const CFGElement &E) {
227    return E.getKind() == MemberDtor;
228  }
229};
230
231/// CFGTemporaryDtor - Represents C++ object destructor implicitly generated
232/// at the end of full expression for temporary object.
233class CFGTemporaryDtor : public CFGImplicitDtor {
234public:
235  CFGTemporaryDtor(CXXBindTemporaryExpr *expr)
236      : CFGImplicitDtor(TemporaryDtor, expr, 0) {}
237
238  const CXXBindTemporaryExpr *getBindTemporaryExpr() const {
239    return static_cast<const CXXBindTemporaryExpr *>(Data1.getPointer());
240  }
241
242private:
243  friend class CFGElement;
244  CFGTemporaryDtor() {}
245  static bool isKind(const CFGElement &E) {
246    return E.getKind() == TemporaryDtor;
247  }
248};
249
250/// CFGTerminator - Represents CFGBlock terminator statement.
251///
252/// TemporaryDtorsBranch bit is set to true if the terminator marks a branch
253/// in control flow of destructors of temporaries. In this case terminator
254/// statement is the same statement that branches control flow in evaluation
255/// of matching full expression.
256class CFGTerminator {
257  llvm::PointerIntPair<Stmt *, 1> Data;
258public:
259  CFGTerminator() {}
260  CFGTerminator(Stmt *S, bool TemporaryDtorsBranch = false)
261      : Data(S, TemporaryDtorsBranch) {}
262
263  Stmt *getStmt() { return Data.getPointer(); }
264  const Stmt *getStmt() const { return Data.getPointer(); }
265
266  bool isTemporaryDtorsBranch() const { return Data.getInt(); }
267
268  operator Stmt *() { return getStmt(); }
269  operator const Stmt *() const { return getStmt(); }
270
271  Stmt *operator->() { return getStmt(); }
272  const Stmt *operator->() const { return getStmt(); }
273
274  Stmt &operator*() { return *getStmt(); }
275  const Stmt &operator*() const { return *getStmt(); }
276
277  operator bool() const { return getStmt(); }
278};
279
280/// CFGBlock - Represents a single basic block in a source-level CFG.
281///  It consists of:
282///
283///  (1) A set of statements/expressions (which may contain subexpressions).
284///  (2) A "terminator" statement (not in the set of statements).
285///  (3) A list of successors and predecessors.
286///
287/// Terminator: The terminator represents the type of control-flow that occurs
288/// at the end of the basic block.  The terminator is a Stmt* referring to an
289/// AST node that has control-flow: if-statements, breaks, loops, etc.
290/// If the control-flow is conditional, the condition expression will appear
291/// within the set of statements in the block (usually the last statement).
292///
293/// Predecessors: the order in the set of predecessors is arbitrary.
294///
295/// Successors: the order in the set of successors is NOT arbitrary.  We
296///  currently have the following orderings based on the terminator:
297///
298///     Terminator       Successor Ordering
299///  -----------------------------------------------------
300///       if            Then Block;  Else Block
301///     ? operator      LHS expression;  RHS expression
302///     &&, ||          expression that uses result of && or ||, RHS
303///
304/// But note that any of that may be NULL in case of optimized-out edges.
305///
306class CFGBlock {
307  class ElementList {
308    typedef BumpVector<CFGElement> ImplTy;
309    ImplTy Impl;
310  public:
311    ElementList(BumpVectorContext &C) : Impl(C, 4) {}
312
313    typedef std::reverse_iterator<ImplTy::iterator>       iterator;
314    typedef std::reverse_iterator<ImplTy::const_iterator> const_iterator;
315    typedef ImplTy::iterator                              reverse_iterator;
316    typedef ImplTy::const_iterator                       const_reverse_iterator;
317    typedef ImplTy::const_reference                       const_reference;
318
319    void push_back(CFGElement e, BumpVectorContext &C) { Impl.push_back(e, C); }
320    reverse_iterator insert(reverse_iterator I, size_t Cnt, CFGElement E,
321        BumpVectorContext &C) {
322      return Impl.insert(I, Cnt, E, C);
323    }
324
325    const_reference front() const { return Impl.back(); }
326    const_reference back() const { return Impl.front(); }
327
328    iterator begin() { return Impl.rbegin(); }
329    iterator end() { return Impl.rend(); }
330    const_iterator begin() const { return Impl.rbegin(); }
331    const_iterator end() const { return Impl.rend(); }
332    reverse_iterator rbegin() { return Impl.begin(); }
333    reverse_iterator rend() { return Impl.end(); }
334    const_reverse_iterator rbegin() const { return Impl.begin(); }
335    const_reverse_iterator rend() const { return Impl.end(); }
336
337   CFGElement operator[](size_t i) const  {
338     assert(i < Impl.size());
339     return Impl[Impl.size() - 1 - i];
340   }
341
342    size_t size() const { return Impl.size(); }
343    bool empty() const { return Impl.empty(); }
344  };
345
346  /// Stmts - The set of statements in the basic block.
347  ElementList Elements;
348
349  /// Label - An (optional) label that prefixes the executable
350  ///  statements in the block.  When this variable is non-NULL, it is
351  ///  either an instance of LabelStmt, SwitchCase or CXXCatchStmt.
352  Stmt *Label;
353
354  /// Terminator - The terminator for a basic block that
355  ///  indicates the type of control-flow that occurs between a block
356  ///  and its successors.
357  CFGTerminator Terminator;
358
359  /// LoopTarget - Some blocks are used to represent the "loop edge" to
360  ///  the start of a loop from within the loop body.  This Stmt* will be
361  ///  refer to the loop statement for such blocks (and be null otherwise).
362  const Stmt *LoopTarget;
363
364  /// BlockID - A numerical ID assigned to a CFGBlock during construction
365  ///   of the CFG.
366  unsigned BlockID;
367
368  /// Predecessors/Successors - Keep track of the predecessor / successor
369  /// CFG blocks.
370  typedef BumpVector<CFGBlock*> AdjacentBlocks;
371  AdjacentBlocks Preds;
372  AdjacentBlocks Succs;
373
374  /// NoReturn - This bit is set when the basic block contains a function call
375  /// or implicit destructor that is attributed as 'noreturn'. In that case,
376  /// control cannot technically ever proceed past this block. All such blocks
377  /// will have a single immediate successor: the exit block. This allows them
378  /// to be easily reached from the exit block and using this bit quickly
379  /// recognized without scanning the contents of the block.
380  ///
381  /// Optimization Note: This bit could be profitably folded with Terminator's
382  /// storage if the memory usage of CFGBlock becomes an issue.
383  unsigned HasNoReturnElement : 1;
384
385  /// Parent - The parent CFG that owns this CFGBlock.
386  CFG *Parent;
387
388public:
389  explicit CFGBlock(unsigned blockid, BumpVectorContext &C, CFG *parent)
390    : Elements(C), Label(NULL), Terminator(NULL), LoopTarget(NULL),
391      BlockID(blockid), Preds(C, 1), Succs(C, 1), HasNoReturnElement(false),
392      Parent(parent) {}
393  ~CFGBlock() {}
394
395  // Statement iterators
396  typedef ElementList::iterator                      iterator;
397  typedef ElementList::const_iterator                const_iterator;
398  typedef ElementList::reverse_iterator              reverse_iterator;
399  typedef ElementList::const_reverse_iterator        const_reverse_iterator;
400
401  CFGElement                 front()       const { return Elements.front();   }
402  CFGElement                 back()        const { return Elements.back();    }
403
404  iterator                   begin()             { return Elements.begin();   }
405  iterator                   end()               { return Elements.end();     }
406  const_iterator             begin()       const { return Elements.begin();   }
407  const_iterator             end()         const { return Elements.end();     }
408
409  reverse_iterator           rbegin()            { return Elements.rbegin();  }
410  reverse_iterator           rend()              { return Elements.rend();    }
411  const_reverse_iterator     rbegin()      const { return Elements.rbegin();  }
412  const_reverse_iterator     rend()        const { return Elements.rend();    }
413
414  unsigned                   size()        const { return Elements.size();    }
415  bool                       empty()       const { return Elements.empty();   }
416
417  CFGElement operator[](size_t i) const  { return Elements[i]; }
418
419  // CFG iterators
420  typedef AdjacentBlocks::iterator                              pred_iterator;
421  typedef AdjacentBlocks::const_iterator                  const_pred_iterator;
422  typedef AdjacentBlocks::reverse_iterator              pred_reverse_iterator;
423  typedef AdjacentBlocks::const_reverse_iterator  const_pred_reverse_iterator;
424
425  typedef AdjacentBlocks::iterator                              succ_iterator;
426  typedef AdjacentBlocks::const_iterator                  const_succ_iterator;
427  typedef AdjacentBlocks::reverse_iterator              succ_reverse_iterator;
428  typedef AdjacentBlocks::const_reverse_iterator  const_succ_reverse_iterator;
429
430  pred_iterator                pred_begin()        { return Preds.begin();   }
431  pred_iterator                pred_end()          { return Preds.end();     }
432  const_pred_iterator          pred_begin()  const { return Preds.begin();   }
433  const_pred_iterator          pred_end()    const { return Preds.end();     }
434
435  pred_reverse_iterator        pred_rbegin()       { return Preds.rbegin();  }
436  pred_reverse_iterator        pred_rend()         { return Preds.rend();    }
437  const_pred_reverse_iterator  pred_rbegin() const { return Preds.rbegin();  }
438  const_pred_reverse_iterator  pred_rend()   const { return Preds.rend();    }
439
440  succ_iterator                succ_begin()        { return Succs.begin();   }
441  succ_iterator                succ_end()          { return Succs.end();     }
442  const_succ_iterator          succ_begin()  const { return Succs.begin();   }
443  const_succ_iterator          succ_end()    const { return Succs.end();     }
444
445  succ_reverse_iterator        succ_rbegin()       { return Succs.rbegin();  }
446  succ_reverse_iterator        succ_rend()         { return Succs.rend();    }
447  const_succ_reverse_iterator  succ_rbegin() const { return Succs.rbegin();  }
448  const_succ_reverse_iterator  succ_rend()   const { return Succs.rend();    }
449
450  unsigned                     succ_size()   const { return Succs.size();    }
451  bool                         succ_empty()  const { return Succs.empty();   }
452
453  unsigned                     pred_size()   const { return Preds.size();    }
454  bool                         pred_empty()  const { return Preds.empty();   }
455
456
457  class FilterOptions {
458  public:
459    FilterOptions() {
460      IgnoreDefaultsWithCoveredEnums = 0;
461    }
462
463    unsigned IgnoreDefaultsWithCoveredEnums : 1;
464  };
465
466  static bool FilterEdge(const FilterOptions &F, const CFGBlock *Src,
467       const CFGBlock *Dst);
468
469  template <typename IMPL, bool IsPred>
470  class FilteredCFGBlockIterator {
471  private:
472    IMPL I, E;
473    const FilterOptions F;
474    const CFGBlock *From;
475   public:
476    explicit FilteredCFGBlockIterator(const IMPL &i, const IMPL &e,
477              const CFGBlock *from,
478              const FilterOptions &f)
479      : I(i), E(e), F(f), From(from) {}
480
481    bool hasMore() const { return I != E; }
482
483    FilteredCFGBlockIterator &operator++() {
484      do { ++I; } while (hasMore() && Filter(*I));
485      return *this;
486    }
487
488    const CFGBlock *operator*() const { return *I; }
489  private:
490    bool Filter(const CFGBlock *To) {
491      return IsPred ? FilterEdge(F, To, From) : FilterEdge(F, From, To);
492    }
493  };
494
495  typedef FilteredCFGBlockIterator<const_pred_iterator, true>
496          filtered_pred_iterator;
497
498  typedef FilteredCFGBlockIterator<const_succ_iterator, false>
499          filtered_succ_iterator;
500
501  filtered_pred_iterator filtered_pred_start_end(const FilterOptions &f) const {
502    return filtered_pred_iterator(pred_begin(), pred_end(), this, f);
503  }
504
505  filtered_succ_iterator filtered_succ_start_end(const FilterOptions &f) const {
506    return filtered_succ_iterator(succ_begin(), succ_end(), this, f);
507  }
508
509  // Manipulation of block contents
510
511  void setTerminator(Stmt *Statement) { Terminator = Statement; }
512  void setLabel(Stmt *Statement) { Label = Statement; }
513  void setLoopTarget(const Stmt *loopTarget) { LoopTarget = loopTarget; }
514  void setHasNoReturnElement() { HasNoReturnElement = true; }
515
516  CFGTerminator getTerminator() { return Terminator; }
517  const CFGTerminator getTerminator() const { return Terminator; }
518
519  Stmt *getTerminatorCondition();
520
521  const Stmt *getTerminatorCondition() const {
522    return const_cast<CFGBlock*>(this)->getTerminatorCondition();
523  }
524
525  const Stmt *getLoopTarget() const { return LoopTarget; }
526
527  Stmt *getLabel() { return Label; }
528  const Stmt *getLabel() const { return Label; }
529
530  bool hasNoReturnElement() const { return HasNoReturnElement; }
531
532  unsigned getBlockID() const { return BlockID; }
533
534  CFG *getParent() const { return Parent; }
535
536  void dump(const CFG *cfg, const LangOptions &LO, bool ShowColors = false) const;
537  void print(raw_ostream &OS, const CFG* cfg, const LangOptions &LO,
538             bool ShowColors) const;
539  void printTerminator(raw_ostream &OS, const LangOptions &LO) const;
540
541  void addSuccessor(CFGBlock *Block, BumpVectorContext &C) {
542    if (Block)
543      Block->Preds.push_back(this, C);
544    Succs.push_back(Block, C);
545  }
546
547  void appendStmt(Stmt *statement, BumpVectorContext &C) {
548    Elements.push_back(CFGStmt(statement), C);
549  }
550
551  void appendInitializer(CXXCtorInitializer *initializer,
552                        BumpVectorContext &C) {
553    Elements.push_back(CFGInitializer(initializer), C);
554  }
555
556  void appendBaseDtor(const CXXBaseSpecifier *BS, BumpVectorContext &C) {
557    Elements.push_back(CFGBaseDtor(BS), C);
558  }
559
560  void appendMemberDtor(FieldDecl *FD, BumpVectorContext &C) {
561    Elements.push_back(CFGMemberDtor(FD), C);
562  }
563
564  void appendTemporaryDtor(CXXBindTemporaryExpr *E, BumpVectorContext &C) {
565    Elements.push_back(CFGTemporaryDtor(E), C);
566  }
567
568  void appendAutomaticObjDtor(VarDecl *VD, Stmt *S, BumpVectorContext &C) {
569    Elements.push_back(CFGAutomaticObjDtor(VD, S), C);
570  }
571
572  // Destructors must be inserted in reversed order. So insertion is in two
573  // steps. First we prepare space for some number of elements, then we insert
574  // the elements beginning at the last position in prepared space.
575  iterator beginAutomaticObjDtorsInsert(iterator I, size_t Cnt,
576      BumpVectorContext &C) {
577    return iterator(Elements.insert(I.base(), Cnt, CFGElement(), C));
578  }
579  iterator insertAutomaticObjDtor(iterator I, VarDecl *VD, Stmt *S) {
580    *I = CFGAutomaticObjDtor(VD, S);
581    return ++I;
582  }
583};
584
585/// CFG - Represents a source-level, intra-procedural CFG that represents the
586///  control-flow of a Stmt.  The Stmt can represent an entire function body,
587///  or a single expression.  A CFG will always contain one empty block that
588///  represents the Exit point of the CFG.  A CFG will also contain a designated
589///  Entry block.  The CFG solely represents control-flow; it consists of
590///  CFGBlocks which are simply containers of Stmt*'s in the AST the CFG
591///  was constructed from.
592class CFG {
593public:
594  //===--------------------------------------------------------------------===//
595  // CFG Construction & Manipulation.
596  //===--------------------------------------------------------------------===//
597
598  class BuildOptions {
599    std::bitset<Stmt::lastStmtConstant> alwaysAddMask;
600  public:
601    typedef llvm::DenseMap<const Stmt *, const CFGBlock*> ForcedBlkExprs;
602    ForcedBlkExprs **forcedBlkExprs;
603
604    bool PruneTriviallyFalseEdges;
605    bool AddEHEdges;
606    bool AddInitializers;
607    bool AddImplicitDtors;
608    bool AddTemporaryDtors;
609
610    bool alwaysAdd(const Stmt *stmt) const {
611      return alwaysAddMask[stmt->getStmtClass()];
612    }
613
614    BuildOptions &setAlwaysAdd(Stmt::StmtClass stmtClass, bool val = true) {
615      alwaysAddMask[stmtClass] = val;
616      return *this;
617    }
618
619    BuildOptions &setAllAlwaysAdd() {
620      alwaysAddMask.set();
621      return *this;
622    }
623
624    BuildOptions()
625    : forcedBlkExprs(0), PruneTriviallyFalseEdges(true)
626      ,AddEHEdges(false)
627      ,AddInitializers(false)
628      ,AddImplicitDtors(false)
629      ,AddTemporaryDtors(false) {}
630  };
631
632  /// \brief Provides a custom implementation of the iterator class to have the
633  /// same interface as Function::iterator - iterator returns CFGBlock
634  /// (not a pointer to CFGBlock).
635  class graph_iterator {
636  public:
637    typedef const CFGBlock                  value_type;
638    typedef value_type&                     reference;
639    typedef value_type*                     pointer;
640    typedef BumpVector<CFGBlock*>::iterator ImplTy;
641
642    graph_iterator(const ImplTy &i) : I(i) {}
643
644    bool operator==(const graph_iterator &X) const { return I == X.I; }
645    bool operator!=(const graph_iterator &X) const { return I != X.I; }
646
647    reference operator*()    const { return **I; }
648    pointer operator->()     const { return  *I; }
649    operator CFGBlock* ()          { return  *I; }
650
651    graph_iterator &operator++() { ++I; return *this; }
652    graph_iterator &operator--() { --I; return *this; }
653
654  private:
655    ImplTy I;
656  };
657
658  class const_graph_iterator {
659  public:
660    typedef const CFGBlock                  value_type;
661    typedef value_type&                     reference;
662    typedef value_type*                     pointer;
663    typedef BumpVector<CFGBlock*>::const_iterator ImplTy;
664
665    const_graph_iterator(const ImplTy &i) : I(i) {}
666
667    bool operator==(const const_graph_iterator &X) const { return I == X.I; }
668    bool operator!=(const const_graph_iterator &X) const { return I != X.I; }
669
670    reference operator*() const { return **I; }
671    pointer operator->()  const { return  *I; }
672    operator CFGBlock* () const { return  *I; }
673
674    const_graph_iterator &operator++() { ++I; return *this; }
675    const_graph_iterator &operator--() { --I; return *this; }
676
677  private:
678    ImplTy I;
679  };
680
681  /// buildCFG - Builds a CFG from an AST.  The responsibility to free the
682  ///   constructed CFG belongs to the caller.
683  static CFG* buildCFG(const Decl *D, Stmt *AST, ASTContext *C,
684                       const BuildOptions &BO);
685
686  /// createBlock - Create a new block in the CFG.  The CFG owns the block;
687  ///  the caller should not directly free it.
688  CFGBlock *createBlock();
689
690  /// setEntry - Set the entry block of the CFG.  This is typically used
691  ///  only during CFG construction.  Most CFG clients expect that the
692  ///  entry block has no predecessors and contains no statements.
693  void setEntry(CFGBlock *B) { Entry = B; }
694
695  /// setIndirectGotoBlock - Set the block used for indirect goto jumps.
696  ///  This is typically used only during CFG construction.
697  void setIndirectGotoBlock(CFGBlock *B) { IndirectGotoBlock = B; }
698
699  //===--------------------------------------------------------------------===//
700  // Block Iterators
701  //===--------------------------------------------------------------------===//
702
703  typedef BumpVector<CFGBlock*>                    CFGBlockListTy;
704  typedef CFGBlockListTy::iterator                 iterator;
705  typedef CFGBlockListTy::const_iterator           const_iterator;
706  typedef std::reverse_iterator<iterator>          reverse_iterator;
707  typedef std::reverse_iterator<const_iterator>    const_reverse_iterator;
708
709  CFGBlock &                front()                { return *Blocks.front(); }
710  CFGBlock &                back()                 { return *Blocks.back(); }
711
712  iterator                  begin()                { return Blocks.begin(); }
713  iterator                  end()                  { return Blocks.end(); }
714  const_iterator            begin()       const    { return Blocks.begin(); }
715  const_iterator            end()         const    { return Blocks.end(); }
716
717  graph_iterator nodes_begin() { return graph_iterator(Blocks.begin()); }
718  graph_iterator nodes_end() { return graph_iterator(Blocks.end()); }
719  const_graph_iterator nodes_begin() const {
720    return const_graph_iterator(Blocks.begin());
721  }
722  const_graph_iterator nodes_end() const {
723    return const_graph_iterator(Blocks.end());
724  }
725
726  reverse_iterator          rbegin()               { return Blocks.rbegin(); }
727  reverse_iterator          rend()                 { return Blocks.rend(); }
728  const_reverse_iterator    rbegin()      const    { return Blocks.rbegin(); }
729  const_reverse_iterator    rend()        const    { return Blocks.rend(); }
730
731  CFGBlock &                getEntry()             { return *Entry; }
732  const CFGBlock &          getEntry()    const    { return *Entry; }
733  CFGBlock &                getExit()              { return *Exit; }
734  const CFGBlock &          getExit()     const    { return *Exit; }
735
736  CFGBlock *       getIndirectGotoBlock() { return IndirectGotoBlock; }
737  const CFGBlock * getIndirectGotoBlock() const { return IndirectGotoBlock; }
738
739  typedef std::vector<const CFGBlock*>::const_iterator try_block_iterator;
740  try_block_iterator try_blocks_begin() const {
741    return TryDispatchBlocks.begin();
742  }
743  try_block_iterator try_blocks_end() const {
744    return TryDispatchBlocks.end();
745  }
746
747  void addTryDispatchBlock(const CFGBlock *block) {
748    TryDispatchBlocks.push_back(block);
749  }
750
751  //===--------------------------------------------------------------------===//
752  // Member templates useful for various batch operations over CFGs.
753  //===--------------------------------------------------------------------===//
754
755  template <typename CALLBACK>
756  void VisitBlockStmts(CALLBACK& O) const {
757    for (const_iterator I=begin(), E=end(); I != E; ++I)
758      for (CFGBlock::const_iterator BI=(*I)->begin(), BE=(*I)->end();
759           BI != BE; ++BI) {
760        if (CFGStmt stmt = BI->getAs<CFGStmt>())
761          O(const_cast<Stmt*>(stmt.getStmt()));
762      }
763  }
764
765  //===--------------------------------------------------------------------===//
766  // CFG Introspection.
767  //===--------------------------------------------------------------------===//
768
769  struct   BlkExprNumTy {
770    const signed Idx;
771    explicit BlkExprNumTy(signed idx) : Idx(idx) {}
772    explicit BlkExprNumTy() : Idx(-1) {}
773    operator bool() const { return Idx >= 0; }
774    operator unsigned() const { assert(Idx >=0); return (unsigned) Idx; }
775  };
776
777  bool isBlkExpr(const Stmt *S) { return getBlkExprNum(S); }
778  bool isBlkExpr(const Stmt *S) const {
779    return const_cast<CFG*>(this)->isBlkExpr(S);
780  }
781  BlkExprNumTy  getBlkExprNum(const Stmt *S);
782  unsigned      getNumBlkExprs();
783
784  /// getNumBlockIDs - Returns the total number of BlockIDs allocated (which
785  /// start at 0).
786  unsigned getNumBlockIDs() const { return NumBlockIDs; }
787
788  /// size - Return the total number of CFGBlocks within the CFG
789  /// This is simply a renaming of the getNumBlockIDs(). This is necessary
790  /// because the dominator implementation needs such an interface.
791  unsigned size() const { return NumBlockIDs; }
792
793  //===--------------------------------------------------------------------===//
794  // CFG Debugging: Pretty-Printing and Visualization.
795  //===--------------------------------------------------------------------===//
796
797  void viewCFG(const LangOptions &LO) const;
798  void print(raw_ostream &OS, const LangOptions &LO, bool ShowColors) const;
799  void dump(const LangOptions &LO, bool ShowColors) const;
800
801  //===--------------------------------------------------------------------===//
802  // Internal: constructors and data.
803  //===--------------------------------------------------------------------===//
804
805  CFG() : Entry(NULL), Exit(NULL), IndirectGotoBlock(NULL), NumBlockIDs(0),
806          BlkExprMap(NULL), Blocks(BlkBVC, 10) {}
807
808  ~CFG();
809
810  llvm::BumpPtrAllocator& getAllocator() {
811    return BlkBVC.getAllocator();
812  }
813
814  BumpVectorContext &getBumpVectorContext() {
815    return BlkBVC;
816  }
817
818private:
819  CFGBlock *Entry;
820  CFGBlock *Exit;
821  CFGBlock* IndirectGotoBlock;  // Special block to contain collective dispatch
822                                // for indirect gotos
823  unsigned  NumBlockIDs;
824
825  // BlkExprMap - An opaque pointer to prevent inclusion of DenseMap.h.
826  //  It represents a map from Expr* to integers to record the set of
827  //  block-level expressions and their "statement number" in the CFG.
828  void *    BlkExprMap;
829
830  BumpVectorContext BlkBVC;
831
832  CFGBlockListTy Blocks;
833
834  /// C++ 'try' statements are modeled with an indirect dispatch block.
835  /// This is the collection of such blocks present in the CFG.
836  std::vector<const CFGBlock *> TryDispatchBlocks;
837
838};
839} // end namespace clang
840
841//===----------------------------------------------------------------------===//
842// GraphTraits specializations for CFG basic block graphs (source-level CFGs)
843//===----------------------------------------------------------------------===//
844
845namespace llvm {
846
847/// Implement simplify_type for CFGTerminator, so that we can dyn_cast from
848/// CFGTerminator to a specific Stmt class.
849template <> struct simplify_type<const ::clang::CFGTerminator> {
850  typedef const ::clang::Stmt *SimpleType;
851  static SimpleType getSimplifiedValue(const ::clang::CFGTerminator &Val) {
852    return Val.getStmt();
853  }
854};
855
856template <> struct simplify_type< ::clang::CFGTerminator> {
857  typedef ::clang::Stmt *SimpleType;
858  static SimpleType getSimplifiedValue(const ::clang::CFGTerminator &Val) {
859    return const_cast<SimpleType>(Val.getStmt());
860  }
861};
862
863// Traits for: CFGBlock
864
865template <> struct GraphTraits< ::clang::CFGBlock *> {
866  typedef ::clang::CFGBlock NodeType;
867  typedef ::clang::CFGBlock::succ_iterator ChildIteratorType;
868
869  static NodeType* getEntryNode(::clang::CFGBlock *BB)
870  { return BB; }
871
872  static inline ChildIteratorType child_begin(NodeType* N)
873  { return N->succ_begin(); }
874
875  static inline ChildIteratorType child_end(NodeType* N)
876  { return N->succ_end(); }
877};
878
879template <> struct GraphTraits< const ::clang::CFGBlock *> {
880  typedef const ::clang::CFGBlock NodeType;
881  typedef ::clang::CFGBlock::const_succ_iterator ChildIteratorType;
882
883  static NodeType* getEntryNode(const clang::CFGBlock *BB)
884  { return BB; }
885
886  static inline ChildIteratorType child_begin(NodeType* N)
887  { return N->succ_begin(); }
888
889  static inline ChildIteratorType child_end(NodeType* N)
890  { return N->succ_end(); }
891};
892
893template <> struct GraphTraits<Inverse< ::clang::CFGBlock*> > {
894  typedef ::clang::CFGBlock NodeType;
895  typedef ::clang::CFGBlock::const_pred_iterator ChildIteratorType;
896
897  static NodeType *getEntryNode(Inverse< ::clang::CFGBlock*> G)
898  { return G.Graph; }
899
900  static inline ChildIteratorType child_begin(NodeType* N)
901  { return N->pred_begin(); }
902
903  static inline ChildIteratorType child_end(NodeType* N)
904  { return N->pred_end(); }
905};
906
907template <> struct GraphTraits<Inverse<const ::clang::CFGBlock*> > {
908  typedef const ::clang::CFGBlock NodeType;
909  typedef ::clang::CFGBlock::const_pred_iterator ChildIteratorType;
910
911  static NodeType *getEntryNode(Inverse<const ::clang::CFGBlock*> G)
912  { return G.Graph; }
913
914  static inline ChildIteratorType child_begin(NodeType* N)
915  { return N->pred_begin(); }
916
917  static inline ChildIteratorType child_end(NodeType* N)
918  { return N->pred_end(); }
919};
920
921// Traits for: CFG
922
923template <> struct GraphTraits< ::clang::CFG* >
924    : public GraphTraits< ::clang::CFGBlock *>  {
925
926  typedef ::clang::CFG::graph_iterator nodes_iterator;
927
928  static NodeType     *getEntryNode(::clang::CFG* F) { return &F->getEntry(); }
929  static nodes_iterator nodes_begin(::clang::CFG* F) { return F->nodes_begin();}
930  static nodes_iterator   nodes_end(::clang::CFG* F) { return F->nodes_end(); }
931  static unsigned              size(::clang::CFG* F) { return F->size(); }
932};
933
934template <> struct GraphTraits<const ::clang::CFG* >
935    : public GraphTraits<const ::clang::CFGBlock *>  {
936
937  typedef ::clang::CFG::const_graph_iterator nodes_iterator;
938
939  static NodeType *getEntryNode( const ::clang::CFG* F) {
940    return &F->getEntry();
941  }
942  static nodes_iterator nodes_begin( const ::clang::CFG* F) {
943    return F->nodes_begin();
944  }
945  static nodes_iterator nodes_end( const ::clang::CFG* F) {
946    return F->nodes_end();
947  }
948  static unsigned size(const ::clang::CFG* F) {
949    return F->size();
950  }
951};
952
953template <> struct GraphTraits<Inverse< ::clang::CFG*> >
954  : public GraphTraits<Inverse< ::clang::CFGBlock*> > {
955
956  typedef ::clang::CFG::graph_iterator nodes_iterator;
957
958  static NodeType *getEntryNode( ::clang::CFG* F) { return &F->getExit(); }
959  static nodes_iterator nodes_begin( ::clang::CFG* F) {return F->nodes_begin();}
960  static nodes_iterator nodes_end( ::clang::CFG* F) { return F->nodes_end(); }
961};
962
963template <> struct GraphTraits<Inverse<const ::clang::CFG*> >
964  : public GraphTraits<Inverse<const ::clang::CFGBlock*> > {
965
966  typedef ::clang::CFG::const_graph_iterator nodes_iterator;
967
968  static NodeType *getEntryNode(const ::clang::CFG* F) { return &F->getExit(); }
969  static nodes_iterator nodes_begin(const ::clang::CFG* F) {
970    return F->nodes_begin();
971  }
972  static nodes_iterator nodes_end(const ::clang::CFG* F) {
973    return F->nodes_end();
974  }
975};
976} // end llvm namespace
977#endif
978