CFG.h revision 94cf910ac2d1719c1dfc163bbec3953f12efdf6f 
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    Statement,
53    Initializer,
54    // dtor kind
55    AutomaticObjectDtor,
56    BaseDtor,
57    MemberDtor,
58    TemporaryDtor,
59    DTOR_BEGIN = AutomaticObjectDtor,
60    DTOR_END = TemporaryDtor
61  };
62
63protected:
64  // The int bits are used to mark the kind.
65  llvm::PointerIntPair<void *, 2> Data1;
66  llvm::PointerIntPair<void *, 2> Data2;
67
68  CFGElement(Kind kind, const void *Ptr1, const void *Ptr2 = 0)
69    : Data1(const_cast<void*>(Ptr1), ((unsigned) kind) & 0x3),
70      Data2(const_cast<void*>(Ptr2), (((unsigned) kind) >> 2) & 0x3) {}
71
72  CFGElement() {}
73public:
74
75  /// \brief Convert to the specified CFGElement type, asserting that this
76  /// CFGElement is of the desired type.
77  template<typename T>
78  T castAs() const {
79    assert(T::isKind(*this));
80    T t;
81    CFGElement& e = t;
82    e = *this;
83    return t;
84  }
85
86  /// \brief Convert to the specified CFGElement type, returning None if this
87  /// CFGElement is not of the desired type.
88  template<typename T>
89  Optional<T> getAs() const {
90    if (!T::isKind(*this))
91      return None;
92    T t;
93    CFGElement& e = t;
94    e = *this;
95    return t;
96  }
97
98  Kind getKind() const {
99    unsigned x = Data2.getInt();
100    x <<= 2;
101    x |= Data1.getInt();
102    return (Kind) x;
103  }
104};
105
106class CFGStmt : public CFGElement {
107public:
108  CFGStmt(Stmt *S) : CFGElement(Statement, S) {}
109
110  const Stmt *getStmt() const {
111    return static_cast<const Stmt *>(Data1.getPointer());
112  }
113
114private:
115  friend class CFGElement;
116  CFGStmt() {}
117  static bool isKind(const CFGElement &E) {
118    return E.getKind() == Statement;
119  }
120};
121
122/// CFGInitializer - Represents C++ base or member initializer from
123/// constructor's initialization list.
124class CFGInitializer : public CFGElement {
125public:
126  CFGInitializer(CXXCtorInitializer *initializer)
127      : CFGElement(Initializer, initializer) {}
128
129  CXXCtorInitializer* getInitializer() const {
130    return static_cast<CXXCtorInitializer*>(Data1.getPointer());
131  }
132
133private:
134  friend class CFGElement;
135  CFGInitializer() {}
136  static bool isKind(const CFGElement &E) {
137    return E.getKind() == Initializer;
138  }
139};
140
141/// CFGImplicitDtor - Represents C++ object destructor implicitly generated
142/// by compiler on various occasions.
143class CFGImplicitDtor : public CFGElement {
144protected:
145  CFGImplicitDtor() {}
146  CFGImplicitDtor(Kind kind, const void *data1, const void *data2 = 0)
147    : CFGElement(kind, data1, data2) {
148    assert(kind >= DTOR_BEGIN && kind <= DTOR_END);
149  }
150
151public:
152  const CXXDestructorDecl *getDestructorDecl(ASTContext &astContext) const;
153  bool isNoReturn(ASTContext &astContext) const;
154
155private:
156  friend class CFGElement;
157  static bool isKind(const CFGElement &E) {
158    Kind kind = E.getKind();
159    return kind >= DTOR_BEGIN && kind <= DTOR_END;
160  }
161};
162
163/// CFGAutomaticObjDtor - Represents C++ object destructor implicitly generated
164/// for automatic object or temporary bound to const reference at the point
165/// of leaving its local scope.
166class CFGAutomaticObjDtor: public CFGImplicitDtor {
167public:
168  CFGAutomaticObjDtor(const VarDecl *var, const Stmt *stmt)
169      : CFGImplicitDtor(AutomaticObjectDtor, var, stmt) {}
170
171  const VarDecl *getVarDecl() const {
172    return static_cast<VarDecl*>(Data1.getPointer());
173  }
174
175  // Get statement end of which triggered the destructor call.
176  const Stmt *getTriggerStmt() const {
177    return static_cast<Stmt*>(Data2.getPointer());
178  }
179
180private:
181  friend class CFGElement;
182  CFGAutomaticObjDtor() {}
183  static bool isKind(const CFGElement &elem) {
184    return elem.getKind() == AutomaticObjectDtor;
185  }
186};
187
188/// CFGBaseDtor - Represents C++ object destructor implicitly generated for
189/// base object in destructor.
190class CFGBaseDtor : public CFGImplicitDtor {
191public:
192  CFGBaseDtor(const CXXBaseSpecifier *base)
193      : CFGImplicitDtor(BaseDtor, base) {}
194
195  const CXXBaseSpecifier *getBaseSpecifier() const {
196    return static_cast<const CXXBaseSpecifier*>(Data1.getPointer());
197  }
198
199private:
200  friend class CFGElement;
201  CFGBaseDtor() {}
202  static bool isKind(const CFGElement &E) {
203    return E.getKind() == BaseDtor;
204  }
205};
206
207/// CFGMemberDtor - Represents C++ object destructor implicitly generated for
208/// member object in destructor.
209class CFGMemberDtor : public CFGImplicitDtor {
210public:
211  CFGMemberDtor(const FieldDecl *field)
212      : CFGImplicitDtor(MemberDtor, field, 0) {}
213
214  const FieldDecl *getFieldDecl() const {
215    return static_cast<const FieldDecl*>(Data1.getPointer());
216  }
217
218private:
219  friend class CFGElement;
220  CFGMemberDtor() {}
221  static bool isKind(const CFGElement &E) {
222    return E.getKind() == MemberDtor;
223  }
224};
225
226/// CFGTemporaryDtor - Represents C++ object destructor implicitly generated
227/// at the end of full expression for temporary object.
228class CFGTemporaryDtor : public CFGImplicitDtor {
229public:
230  CFGTemporaryDtor(CXXBindTemporaryExpr *expr)
231      : CFGImplicitDtor(TemporaryDtor, expr, 0) {}
232
233  const CXXBindTemporaryExpr *getBindTemporaryExpr() const {
234    return static_cast<const CXXBindTemporaryExpr *>(Data1.getPointer());
235  }
236
237private:
238  friend class CFGElement;
239  CFGTemporaryDtor() {}
240  static bool isKind(const CFGElement &E) {
241    return E.getKind() == TemporaryDtor;
242  }
243};
244
245/// CFGTerminator - Represents CFGBlock terminator statement.
246///
247/// TemporaryDtorsBranch bit is set to true if the terminator marks a branch
248/// in control flow of destructors of temporaries. In this case terminator
249/// statement is the same statement that branches control flow in evaluation
250/// of matching full expression.
251class CFGTerminator {
252  llvm::PointerIntPair<Stmt *, 1> Data;
253public:
254  CFGTerminator() {}
255  CFGTerminator(Stmt *S, bool TemporaryDtorsBranch = false)
256      : Data(S, TemporaryDtorsBranch) {}
257
258  Stmt *getStmt() { return Data.getPointer(); }
259  const Stmt *getStmt() const { return Data.getPointer(); }
260
261  bool isTemporaryDtorsBranch() const { return Data.getInt(); }
262
263  operator Stmt *() { return getStmt(); }
264  operator const Stmt *() const { return getStmt(); }
265
266  Stmt *operator->() { return getStmt(); }
267  const Stmt *operator->() const { return getStmt(); }
268
269  Stmt &operator*() { return *getStmt(); }
270  const Stmt &operator*() const { return *getStmt(); }
271
272  operator bool() const { return getStmt(); }
273};
274
275/// CFGBlock - Represents a single basic block in a source-level CFG.
276///  It consists of:
277///
278///  (1) A set of statements/expressions (which may contain subexpressions).
279///  (2) A "terminator" statement (not in the set of statements).
280///  (3) A list of successors and predecessors.
281///
282/// Terminator: The terminator represents the type of control-flow that occurs
283/// at the end of the basic block.  The terminator is a Stmt* referring to an
284/// AST node that has control-flow: if-statements, breaks, loops, etc.
285/// If the control-flow is conditional, the condition expression will appear
286/// within the set of statements in the block (usually the last statement).
287///
288/// Predecessors: the order in the set of predecessors is arbitrary.
289///
290/// Successors: the order in the set of successors is NOT arbitrary.  We
291///  currently have the following orderings based on the terminator:
292///
293///     Terminator       Successor Ordering
294///  -----------------------------------------------------
295///       if            Then Block;  Else Block
296///     ? operator      LHS expression;  RHS expression
297///     &&, ||          expression that uses result of && or ||, RHS
298///
299/// But note that any of that may be NULL in case of optimized-out edges.
300///
301class CFGBlock {
302  class ElementList {
303    typedef BumpVector<CFGElement> ImplTy;
304    ImplTy Impl;
305  public:
306    ElementList(BumpVectorContext &C) : Impl(C, 4) {}
307
308    typedef std::reverse_iterator<ImplTy::iterator>       iterator;
309    typedef std::reverse_iterator<ImplTy::const_iterator> const_iterator;
310    typedef ImplTy::iterator                              reverse_iterator;
311    typedef ImplTy::const_iterator                       const_reverse_iterator;
312    typedef ImplTy::const_reference                       const_reference;
313
314    void push_back(CFGElement e, BumpVectorContext &C) { Impl.push_back(e, C); }
315    reverse_iterator insert(reverse_iterator I, size_t Cnt, CFGElement E,
316        BumpVectorContext &C) {
317      return Impl.insert(I, Cnt, E, C);
318    }
319
320    const_reference front() const { return Impl.back(); }
321    const_reference back() const { return Impl.front(); }
322
323    iterator begin() { return Impl.rbegin(); }
324    iterator end() { return Impl.rend(); }
325    const_iterator begin() const { return Impl.rbegin(); }
326    const_iterator end() const { return Impl.rend(); }
327    reverse_iterator rbegin() { return Impl.begin(); }
328    reverse_iterator rend() { return Impl.end(); }
329    const_reverse_iterator rbegin() const { return Impl.begin(); }
330    const_reverse_iterator rend() const { return Impl.end(); }
331
332   CFGElement operator[](size_t i) const  {
333     assert(i < Impl.size());
334     return Impl[Impl.size() - 1 - i];
335   }
336
337    size_t size() const { return Impl.size(); }
338    bool empty() const { return Impl.empty(); }
339  };
340
341  /// Stmts - The set of statements in the basic block.
342  ElementList Elements;
343
344  /// Label - An (optional) label that prefixes the executable
345  ///  statements in the block.  When this variable is non-NULL, it is
346  ///  either an instance of LabelStmt, SwitchCase or CXXCatchStmt.
347  Stmt *Label;
348
349  /// Terminator - The terminator for a basic block that
350  ///  indicates the type of control-flow that occurs between a block
351  ///  and its successors.
352  CFGTerminator Terminator;
353
354  /// LoopTarget - Some blocks are used to represent the "loop edge" to
355  ///  the start of a loop from within the loop body.  This Stmt* will be
356  ///  refer to the loop statement for such blocks (and be null otherwise).
357  const Stmt *LoopTarget;
358
359  /// BlockID - A numerical ID assigned to a CFGBlock during construction
360  ///   of the CFG.
361  unsigned BlockID;
362
363  /// Predecessors/Successors - Keep track of the predecessor / successor
364  /// CFG blocks.
365  typedef BumpVector<CFGBlock*> AdjacentBlocks;
366  AdjacentBlocks Preds;
367  AdjacentBlocks Succs;
368
369  /// NoReturn - This bit is set when the basic block contains a function call
370  /// or implicit destructor that is attributed as 'noreturn'. In that case,
371  /// control cannot technically ever proceed past this block. All such blocks
372  /// will have a single immediate successor: the exit block. This allows them
373  /// to be easily reached from the exit block and using this bit quickly
374  /// recognized without scanning the contents of the block.
375  ///
376  /// Optimization Note: This bit could be profitably folded with Terminator's
377  /// storage if the memory usage of CFGBlock becomes an issue.
378  unsigned HasNoReturnElement : 1;
379
380  /// Parent - The parent CFG that owns this CFGBlock.
381  CFG *Parent;
382
383public:
384  explicit CFGBlock(unsigned blockid, BumpVectorContext &C, CFG *parent)
385    : Elements(C), Label(NULL), Terminator(NULL), LoopTarget(NULL),
386      BlockID(blockid), Preds(C, 1), Succs(C, 1), HasNoReturnElement(false),
387      Parent(parent) {}
388  ~CFGBlock() {}
389
390  // Statement iterators
391  typedef ElementList::iterator                      iterator;
392  typedef ElementList::const_iterator                const_iterator;
393  typedef ElementList::reverse_iterator              reverse_iterator;
394  typedef ElementList::const_reverse_iterator        const_reverse_iterator;
395
396  CFGElement                 front()       const { return Elements.front();   }
397  CFGElement                 back()        const { return Elements.back();    }
398
399  iterator                   begin()             { return Elements.begin();   }
400  iterator                   end()               { return Elements.end();     }
401  const_iterator             begin()       const { return Elements.begin();   }
402  const_iterator             end()         const { return Elements.end();     }
403
404  reverse_iterator           rbegin()            { return Elements.rbegin();  }
405  reverse_iterator           rend()              { return Elements.rend();    }
406  const_reverse_iterator     rbegin()      const { return Elements.rbegin();  }
407  const_reverse_iterator     rend()        const { return Elements.rend();    }
408
409  unsigned                   size()        const { return Elements.size();    }
410  bool                       empty()       const { return Elements.empty();   }
411
412  CFGElement operator[](size_t i) const  { return Elements[i]; }
413
414  // CFG iterators
415  typedef AdjacentBlocks::iterator                              pred_iterator;
416  typedef AdjacentBlocks::const_iterator                  const_pred_iterator;
417  typedef AdjacentBlocks::reverse_iterator              pred_reverse_iterator;
418  typedef AdjacentBlocks::const_reverse_iterator  const_pred_reverse_iterator;
419
420  typedef AdjacentBlocks::iterator                              succ_iterator;
421  typedef AdjacentBlocks::const_iterator                  const_succ_iterator;
422  typedef AdjacentBlocks::reverse_iterator              succ_reverse_iterator;
423  typedef AdjacentBlocks::const_reverse_iterator  const_succ_reverse_iterator;
424
425  pred_iterator                pred_begin()        { return Preds.begin();   }
426  pred_iterator                pred_end()          { return Preds.end();     }
427  const_pred_iterator          pred_begin()  const { return Preds.begin();   }
428  const_pred_iterator          pred_end()    const { return Preds.end();     }
429
430  pred_reverse_iterator        pred_rbegin()       { return Preds.rbegin();  }
431  pred_reverse_iterator        pred_rend()         { return Preds.rend();    }
432  const_pred_reverse_iterator  pred_rbegin() const { return Preds.rbegin();  }
433  const_pred_reverse_iterator  pred_rend()   const { return Preds.rend();    }
434
435  succ_iterator                succ_begin()        { return Succs.begin();   }
436  succ_iterator                succ_end()          { return Succs.end();     }
437  const_succ_iterator          succ_begin()  const { return Succs.begin();   }
438  const_succ_iterator          succ_end()    const { return Succs.end();     }
439
440  succ_reverse_iterator        succ_rbegin()       { return Succs.rbegin();  }
441  succ_reverse_iterator        succ_rend()         { return Succs.rend();    }
442  const_succ_reverse_iterator  succ_rbegin() const { return Succs.rbegin();  }
443  const_succ_reverse_iterator  succ_rend()   const { return Succs.rend();    }
444
445  unsigned                     succ_size()   const { return Succs.size();    }
446  bool                         succ_empty()  const { return Succs.empty();   }
447
448  unsigned                     pred_size()   const { return Preds.size();    }
449  bool                         pred_empty()  const { return Preds.empty();   }
450
451
452  class FilterOptions {
453  public:
454    FilterOptions() {
455      IgnoreDefaultsWithCoveredEnums = 0;
456    }
457
458    unsigned IgnoreDefaultsWithCoveredEnums : 1;
459  };
460
461  static bool FilterEdge(const FilterOptions &F, const CFGBlock *Src,
462       const CFGBlock *Dst);
463
464  template <typename IMPL, bool IsPred>
465  class FilteredCFGBlockIterator {
466  private:
467    IMPL I, E;
468    const FilterOptions F;
469    const CFGBlock *From;
470   public:
471    explicit FilteredCFGBlockIterator(const IMPL &i, const IMPL &e,
472              const CFGBlock *from,
473              const FilterOptions &f)
474      : I(i), E(e), F(f), From(from) {}
475
476    bool hasMore() const { return I != E; }
477
478    FilteredCFGBlockIterator &operator++() {
479      do { ++I; } while (hasMore() && Filter(*I));
480      return *this;
481    }
482
483    const CFGBlock *operator*() const { return *I; }
484  private:
485    bool Filter(const CFGBlock *To) {
486      return IsPred ? FilterEdge(F, To, From) : FilterEdge(F, From, To);
487    }
488  };
489
490  typedef FilteredCFGBlockIterator<const_pred_iterator, true>
491          filtered_pred_iterator;
492
493  typedef FilteredCFGBlockIterator<const_succ_iterator, false>
494          filtered_succ_iterator;
495
496  filtered_pred_iterator filtered_pred_start_end(const FilterOptions &f) const {
497    return filtered_pred_iterator(pred_begin(), pred_end(), this, f);
498  }
499
500  filtered_succ_iterator filtered_succ_start_end(const FilterOptions &f) const {
501    return filtered_succ_iterator(succ_begin(), succ_end(), this, f);
502  }
503
504  // Manipulation of block contents
505
506  void setTerminator(Stmt *Statement) { Terminator = Statement; }
507  void setLabel(Stmt *Statement) { Label = Statement; }
508  void setLoopTarget(const Stmt *loopTarget) { LoopTarget = loopTarget; }
509  void setHasNoReturnElement() { HasNoReturnElement = true; }
510
511  CFGTerminator getTerminator() { return Terminator; }
512  const CFGTerminator getTerminator() const { return Terminator; }
513
514  Stmt *getTerminatorCondition();
515
516  const Stmt *getTerminatorCondition() const {
517    return const_cast<CFGBlock*>(this)->getTerminatorCondition();
518  }
519
520  const Stmt *getLoopTarget() const { return LoopTarget; }
521
522  Stmt *getLabel() { return Label; }
523  const Stmt *getLabel() const { return Label; }
524
525  bool hasNoReturnElement() const { return HasNoReturnElement; }
526
527  unsigned getBlockID() const { return BlockID; }
528
529  CFG *getParent() const { return Parent; }
530
531  void dump(const CFG *cfg, const LangOptions &LO, bool ShowColors = false) const;
532  void print(raw_ostream &OS, const CFG* cfg, const LangOptions &LO,
533             bool ShowColors) const;
534  void printTerminator(raw_ostream &OS, const LangOptions &LO) const;
535
536  void addSuccessor(CFGBlock *Block, BumpVectorContext &C) {
537    if (Block)
538      Block->Preds.push_back(this, C);
539    Succs.push_back(Block, C);
540  }
541
542  void appendStmt(Stmt *statement, BumpVectorContext &C) {
543    Elements.push_back(CFGStmt(statement), C);
544  }
545
546  void appendInitializer(CXXCtorInitializer *initializer,
547                        BumpVectorContext &C) {
548    Elements.push_back(CFGInitializer(initializer), C);
549  }
550
551  void appendBaseDtor(const CXXBaseSpecifier *BS, BumpVectorContext &C) {
552    Elements.push_back(CFGBaseDtor(BS), C);
553  }
554
555  void appendMemberDtor(FieldDecl *FD, BumpVectorContext &C) {
556    Elements.push_back(CFGMemberDtor(FD), C);
557  }
558
559  void appendTemporaryDtor(CXXBindTemporaryExpr *E, BumpVectorContext &C) {
560    Elements.push_back(CFGTemporaryDtor(E), C);
561  }
562
563  void appendAutomaticObjDtor(VarDecl *VD, Stmt *S, BumpVectorContext &C) {
564    Elements.push_back(CFGAutomaticObjDtor(VD, S), C);
565  }
566
567  // Destructors must be inserted in reversed order. So insertion is in two
568  // steps. First we prepare space for some number of elements, then we insert
569  // the elements beginning at the last position in prepared space.
570  iterator beginAutomaticObjDtorsInsert(iterator I, size_t Cnt,
571      BumpVectorContext &C) {
572    return iterator(Elements.insert(I.base(), Cnt, CFGAutomaticObjDtor(0, 0), C));
573  }
574  iterator insertAutomaticObjDtor(iterator I, VarDecl *VD, Stmt *S) {
575    *I = CFGAutomaticObjDtor(VD, S);
576    return ++I;
577  }
578};
579
580/// CFG - Represents a source-level, intra-procedural CFG that represents the
581///  control-flow of a Stmt.  The Stmt can represent an entire function body,
582///  or a single expression.  A CFG will always contain one empty block that
583///  represents the Exit point of the CFG.  A CFG will also contain a designated
584///  Entry block.  The CFG solely represents control-flow; it consists of
585///  CFGBlocks which are simply containers of Stmt*'s in the AST the CFG
586///  was constructed from.
587class CFG {
588public:
589  //===--------------------------------------------------------------------===//
590  // CFG Construction & Manipulation.
591  //===--------------------------------------------------------------------===//
592
593  class BuildOptions {
594    std::bitset<Stmt::lastStmtConstant> alwaysAddMask;
595  public:
596    typedef llvm::DenseMap<const Stmt *, const CFGBlock*> ForcedBlkExprs;
597    ForcedBlkExprs **forcedBlkExprs;
598
599    bool PruneTriviallyFalseEdges;
600    bool AddEHEdges;
601    bool AddInitializers;
602    bool AddImplicitDtors;
603    bool AddTemporaryDtors;
604
605    bool alwaysAdd(const Stmt *stmt) const {
606      return alwaysAddMask[stmt->getStmtClass()];
607    }
608
609    BuildOptions &setAlwaysAdd(Stmt::StmtClass stmtClass, bool val = true) {
610      alwaysAddMask[stmtClass] = val;
611      return *this;
612    }
613
614    BuildOptions &setAllAlwaysAdd() {
615      alwaysAddMask.set();
616      return *this;
617    }
618
619    BuildOptions()
620    : forcedBlkExprs(0), PruneTriviallyFalseEdges(true)
621      ,AddEHEdges(false)
622      ,AddInitializers(false)
623      ,AddImplicitDtors(false)
624      ,AddTemporaryDtors(false) {}
625  };
626
627  /// \brief Provides a custom implementation of the iterator class to have the
628  /// same interface as Function::iterator - iterator returns CFGBlock
629  /// (not a pointer to CFGBlock).
630  class graph_iterator {
631  public:
632    typedef const CFGBlock                  value_type;
633    typedef value_type&                     reference;
634    typedef value_type*                     pointer;
635    typedef BumpVector<CFGBlock*>::iterator ImplTy;
636
637    graph_iterator(const ImplTy &i) : I(i) {}
638
639    bool operator==(const graph_iterator &X) const { return I == X.I; }
640    bool operator!=(const graph_iterator &X) const { return I != X.I; }
641
642    reference operator*()    const { return **I; }
643    pointer operator->()     const { return  *I; }
644    operator CFGBlock* ()          { return  *I; }
645
646    graph_iterator &operator++() { ++I; return *this; }
647    graph_iterator &operator--() { --I; return *this; }
648
649  private:
650    ImplTy I;
651  };
652
653  class const_graph_iterator {
654  public:
655    typedef const CFGBlock                  value_type;
656    typedef value_type&                     reference;
657    typedef value_type*                     pointer;
658    typedef BumpVector<CFGBlock*>::const_iterator ImplTy;
659
660    const_graph_iterator(const ImplTy &i) : I(i) {}
661
662    bool operator==(const const_graph_iterator &X) const { return I == X.I; }
663    bool operator!=(const const_graph_iterator &X) const { return I != X.I; }
664
665    reference operator*() const { return **I; }
666    pointer operator->()  const { return  *I; }
667    operator CFGBlock* () const { return  *I; }
668
669    const_graph_iterator &operator++() { ++I; return *this; }
670    const_graph_iterator &operator--() { --I; return *this; }
671
672  private:
673    ImplTy I;
674  };
675
676  /// buildCFG - Builds a CFG from an AST.  The responsibility to free the
677  ///   constructed CFG belongs to the caller.
678  static CFG* buildCFG(const Decl *D, Stmt *AST, ASTContext *C,
679                       const BuildOptions &BO);
680
681  /// createBlock - Create a new block in the CFG.  The CFG owns the block;
682  ///  the caller should not directly free it.
683  CFGBlock *createBlock();
684
685  /// setEntry - Set the entry block of the CFG.  This is typically used
686  ///  only during CFG construction.  Most CFG clients expect that the
687  ///  entry block has no predecessors and contains no statements.
688  void setEntry(CFGBlock *B) { Entry = B; }
689
690  /// setIndirectGotoBlock - Set the block used for indirect goto jumps.
691  ///  This is typically used only during CFG construction.
692  void setIndirectGotoBlock(CFGBlock *B) { IndirectGotoBlock = B; }
693
694  //===--------------------------------------------------------------------===//
695  // Block Iterators
696  //===--------------------------------------------------------------------===//
697
698  typedef BumpVector<CFGBlock*>                    CFGBlockListTy;
699  typedef CFGBlockListTy::iterator                 iterator;
700  typedef CFGBlockListTy::const_iterator           const_iterator;
701  typedef std::reverse_iterator<iterator>          reverse_iterator;
702  typedef std::reverse_iterator<const_iterator>    const_reverse_iterator;
703
704  CFGBlock &                front()                { return *Blocks.front(); }
705  CFGBlock &                back()                 { return *Blocks.back(); }
706
707  iterator                  begin()                { return Blocks.begin(); }
708  iterator                  end()                  { return Blocks.end(); }
709  const_iterator            begin()       const    { return Blocks.begin(); }
710  const_iterator            end()         const    { return Blocks.end(); }
711
712  graph_iterator nodes_begin() { return graph_iterator(Blocks.begin()); }
713  graph_iterator nodes_end() { return graph_iterator(Blocks.end()); }
714  const_graph_iterator nodes_begin() const {
715    return const_graph_iterator(Blocks.begin());
716  }
717  const_graph_iterator nodes_end() const {
718    return const_graph_iterator(Blocks.end());
719  }
720
721  reverse_iterator          rbegin()               { return Blocks.rbegin(); }
722  reverse_iterator          rend()                 { return Blocks.rend(); }
723  const_reverse_iterator    rbegin()      const    { return Blocks.rbegin(); }
724  const_reverse_iterator    rend()        const    { return Blocks.rend(); }
725
726  CFGBlock &                getEntry()             { return *Entry; }
727  const CFGBlock &          getEntry()    const    { return *Entry; }
728  CFGBlock &                getExit()              { return *Exit; }
729  const CFGBlock &          getExit()     const    { return *Exit; }
730
731  CFGBlock *       getIndirectGotoBlock() { return IndirectGotoBlock; }
732  const CFGBlock * getIndirectGotoBlock() const { return IndirectGotoBlock; }
733
734  typedef std::vector<const CFGBlock*>::const_iterator try_block_iterator;
735  try_block_iterator try_blocks_begin() const {
736    return TryDispatchBlocks.begin();
737  }
738  try_block_iterator try_blocks_end() const {
739    return TryDispatchBlocks.end();
740  }
741
742  void addTryDispatchBlock(const CFGBlock *block) {
743    TryDispatchBlocks.push_back(block);
744  }
745
746  //===--------------------------------------------------------------------===//
747  // Member templates useful for various batch operations over CFGs.
748  //===--------------------------------------------------------------------===//
749
750  template <typename CALLBACK>
751  void VisitBlockStmts(CALLBACK& O) const {
752    for (const_iterator I=begin(), E=end(); I != E; ++I)
753      for (CFGBlock::const_iterator BI=(*I)->begin(), BE=(*I)->end();
754           BI != BE; ++BI) {
755        if (Optional<CFGStmt> stmt = BI->getAs<CFGStmt>())
756          O(const_cast<Stmt*>(stmt->getStmt()));
757      }
758  }
759
760  //===--------------------------------------------------------------------===//
761  // CFG Introspection.
762  //===--------------------------------------------------------------------===//
763
764  struct   BlkExprNumTy {
765    const signed Idx;
766    explicit BlkExprNumTy(signed idx) : Idx(idx) {}
767    explicit BlkExprNumTy() : Idx(-1) {}
768    operator bool() const { return Idx >= 0; }
769    operator unsigned() const { assert(Idx >=0); return (unsigned) Idx; }
770  };
771
772  bool isBlkExpr(const Stmt *S) { return getBlkExprNum(S); }
773  bool isBlkExpr(const Stmt *S) const {
774    return const_cast<CFG*>(this)->isBlkExpr(S);
775  }
776  BlkExprNumTy  getBlkExprNum(const Stmt *S);
777  unsigned      getNumBlkExprs();
778
779  /// getNumBlockIDs - Returns the total number of BlockIDs allocated (which
780  /// start at 0).
781  unsigned getNumBlockIDs() const { return NumBlockIDs; }
782
783  /// size - Return the total number of CFGBlocks within the CFG
784  /// This is simply a renaming of the getNumBlockIDs(). This is necessary
785  /// because the dominator implementation needs such an interface.
786  unsigned size() const { return NumBlockIDs; }
787
788  //===--------------------------------------------------------------------===//
789  // CFG Debugging: Pretty-Printing and Visualization.
790  //===--------------------------------------------------------------------===//
791
792  void viewCFG(const LangOptions &LO) const;
793  void print(raw_ostream &OS, const LangOptions &LO, bool ShowColors) const;
794  void dump(const LangOptions &LO, bool ShowColors) const;
795
796  //===--------------------------------------------------------------------===//
797  // Internal: constructors and data.
798  //===--------------------------------------------------------------------===//
799
800  CFG() : Entry(NULL), Exit(NULL), IndirectGotoBlock(NULL), NumBlockIDs(0),
801          BlkExprMap(NULL), Blocks(BlkBVC, 10) {}
802
803  ~CFG();
804
805  llvm::BumpPtrAllocator& getAllocator() {
806    return BlkBVC.getAllocator();
807  }
808
809  BumpVectorContext &getBumpVectorContext() {
810    return BlkBVC;
811  }
812
813private:
814  CFGBlock *Entry;
815  CFGBlock *Exit;
816  CFGBlock* IndirectGotoBlock;  // Special block to contain collective dispatch
817                                // for indirect gotos
818  unsigned  NumBlockIDs;
819
820  // BlkExprMap - An opaque pointer to prevent inclusion of DenseMap.h.
821  //  It represents a map from Expr* to integers to record the set of
822  //  block-level expressions and their "statement number" in the CFG.
823  void *    BlkExprMap;
824
825  BumpVectorContext BlkBVC;
826
827  CFGBlockListTy Blocks;
828
829  /// C++ 'try' statements are modeled with an indirect dispatch block.
830  /// This is the collection of such blocks present in the CFG.
831  std::vector<const CFGBlock *> TryDispatchBlocks;
832
833};
834} // end namespace clang
835
836//===----------------------------------------------------------------------===//
837// GraphTraits specializations for CFG basic block graphs (source-level CFGs)
838//===----------------------------------------------------------------------===//
839
840namespace llvm {
841
842/// Implement simplify_type for CFGTerminator, so that we can dyn_cast from
843/// CFGTerminator to a specific Stmt class.
844template <> struct simplify_type< ::clang::CFGTerminator> {
845  typedef ::clang::Stmt *SimpleType;
846  static SimpleType getSimplifiedValue(::clang::CFGTerminator Val) {
847    return Val.getStmt();
848  }
849};
850
851// Traits for: CFGBlock
852
853template <> struct GraphTraits< ::clang::CFGBlock *> {
854  typedef ::clang::CFGBlock NodeType;
855  typedef ::clang::CFGBlock::succ_iterator ChildIteratorType;
856
857  static NodeType* getEntryNode(::clang::CFGBlock *BB)
858  { return BB; }
859
860  static inline ChildIteratorType child_begin(NodeType* N)
861  { return N->succ_begin(); }
862
863  static inline ChildIteratorType child_end(NodeType* N)
864  { return N->succ_end(); }
865};
866
867template <> struct GraphTraits< const ::clang::CFGBlock *> {
868  typedef const ::clang::CFGBlock NodeType;
869  typedef ::clang::CFGBlock::const_succ_iterator ChildIteratorType;
870
871  static NodeType* getEntryNode(const clang::CFGBlock *BB)
872  { return BB; }
873
874  static inline ChildIteratorType child_begin(NodeType* N)
875  { return N->succ_begin(); }
876
877  static inline ChildIteratorType child_end(NodeType* N)
878  { return N->succ_end(); }
879};
880
881template <> struct GraphTraits<Inverse< ::clang::CFGBlock*> > {
882  typedef ::clang::CFGBlock NodeType;
883  typedef ::clang::CFGBlock::const_pred_iterator ChildIteratorType;
884
885  static NodeType *getEntryNode(Inverse< ::clang::CFGBlock*> G)
886  { return G.Graph; }
887
888  static inline ChildIteratorType child_begin(NodeType* N)
889  { return N->pred_begin(); }
890
891  static inline ChildIteratorType child_end(NodeType* N)
892  { return N->pred_end(); }
893};
894
895template <> struct GraphTraits<Inverse<const ::clang::CFGBlock*> > {
896  typedef const ::clang::CFGBlock NodeType;
897  typedef ::clang::CFGBlock::const_pred_iterator ChildIteratorType;
898
899  static NodeType *getEntryNode(Inverse<const ::clang::CFGBlock*> G)
900  { return G.Graph; }
901
902  static inline ChildIteratorType child_begin(NodeType* N)
903  { return N->pred_begin(); }
904
905  static inline ChildIteratorType child_end(NodeType* N)
906  { return N->pred_end(); }
907};
908
909// Traits for: CFG
910
911template <> struct GraphTraits< ::clang::CFG* >
912    : public GraphTraits< ::clang::CFGBlock *>  {
913
914  typedef ::clang::CFG::graph_iterator nodes_iterator;
915
916  static NodeType     *getEntryNode(::clang::CFG* F) { return &F->getEntry(); }
917  static nodes_iterator nodes_begin(::clang::CFG* F) { return F->nodes_begin();}
918  static nodes_iterator   nodes_end(::clang::CFG* F) { return F->nodes_end(); }
919  static unsigned              size(::clang::CFG* F) { return F->size(); }
920};
921
922template <> struct GraphTraits<const ::clang::CFG* >
923    : public GraphTraits<const ::clang::CFGBlock *>  {
924
925  typedef ::clang::CFG::const_graph_iterator nodes_iterator;
926
927  static NodeType *getEntryNode( const ::clang::CFG* F) {
928    return &F->getEntry();
929  }
930  static nodes_iterator nodes_begin( const ::clang::CFG* F) {
931    return F->nodes_begin();
932  }
933  static nodes_iterator nodes_end( const ::clang::CFG* F) {
934    return F->nodes_end();
935  }
936  static unsigned size(const ::clang::CFG* F) {
937    return F->size();
938  }
939};
940
941template <> struct GraphTraits<Inverse< ::clang::CFG*> >
942  : public GraphTraits<Inverse< ::clang::CFGBlock*> > {
943
944  typedef ::clang::CFG::graph_iterator nodes_iterator;
945
946  static NodeType *getEntryNode( ::clang::CFG* F) { return &F->getExit(); }
947  static nodes_iterator nodes_begin( ::clang::CFG* F) {return F->nodes_begin();}
948  static nodes_iterator nodes_end( ::clang::CFG* F) { return F->nodes_end(); }
949};
950
951template <> struct GraphTraits<Inverse<const ::clang::CFG*> >
952  : public GraphTraits<Inverse<const ::clang::CFGBlock*> > {
953
954  typedef ::clang::CFG::const_graph_iterator nodes_iterator;
955
956  static NodeType *getEntryNode(const ::clang::CFG* F) { return &F->getExit(); }
957  static nodes_iterator nodes_begin(const ::clang::CFG* F) {
958    return F->nodes_begin();
959  }
960  static nodes_iterator nodes_end(const ::clang::CFG* F) {
961    return F->nodes_end();
962  }
963};
964} // end llvm namespace
965#endif
966