LexicalScopes.h revision 5bc942cc3cc970836d48d8ad276ef3b2b1120ffc 
1//===- LexicalScopes.cpp - Collecting lexical scope info -*- 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 implements LexicalScopes analysis.
11//
12// This pass collects lexical scope information and maps machine instructions
13// to respective lexical scopes.
14//
15//===----------------------------------------------------------------------===//
16
17#ifndef LLVM_CODEGEN_LEXICALSCOPES_H
18#define LLVM_CODEGEN_LEXICALSCOPES_H
19
20#include "llvm/Metadata.h"
21#include "llvm/ADT/DenseMap.h"
22#include "llvm/ADT/SmallPtrSet.h"
23#include "llvm/ADT/SmallVector.h"
24#include "llvm/Support/DebugLoc.h"
25#include "llvm/Support/ValueHandle.h"
26#include <utility>
27namespace llvm {
28
29class MachineInstr;
30class MachineBasicBlock;
31class MachineFunction;
32class LexicalScope;
33
34//===----------------------------------------------------------------------===//
35/// InsnRange - This is used to track range of instructions with identical
36/// lexical scope.
37///
38typedef std::pair<const MachineInstr *, const MachineInstr *> InsnRange;
39
40//===----------------------------------------------------------------------===//
41/// LexicalScopes -  This class provides interface to collect and use lexical
42/// scoping information from machine instruction.
43///
44class LexicalScopes {
45public:
46  LexicalScopes() : MF(NULL),  CurrentFnLexicalScope(NULL) { }
47  ~LexicalScopes();
48
49  /// initialize - Scan machine function and constuct lexical scope nest.
50  virtual void initialize(const MachineFunction &);
51
52  /// releaseMemory - release memory.
53  virtual void releaseMemory();
54
55  /// empty - Return true if there is any lexical scope information available.
56  bool empty() { return CurrentFnLexicalScope == NULL; }
57
58  /// isCurrentFunctionScope - Return true if given lexical scope represents
59  /// current function.
60  bool isCurrentFunctionScope(const LexicalScope *LS) {
61    return LS == CurrentFnLexicalScope;
62  }
63
64  /// getCurrentFunctionScope - Return lexical scope for the current function.
65  LexicalScope *getCurrentFunctionScope() const { return CurrentFnLexicalScope;}
66
67  /// getMachineBasicBlocks - Populate given set using machine basic blocks
68  /// which have machine instructions that belong to lexical scope identified by
69  /// DebugLoc.
70  void getMachineBasicBlocks(DebugLoc DL,
71                             SmallPtrSet<const MachineBasicBlock*, 4> &MBBs);
72
73  /// dominates - Return true if DebugLoc's lexical scope dominates at least one
74  /// machine instruction's lexical scope in a given machine basic block.
75  bool dominates(DebugLoc DL, MachineBasicBlock *MBB);
76
77  /// findLexicalScope - Find lexical scope, either regular or inlined, for the
78  /// given DebugLoc. Return NULL if not found.
79  LexicalScope *findLexicalScope(DebugLoc DL);
80
81  /// getAbstractScopesList - Return a reference to list of abstract scopes.
82  SmallVector<LexicalScope *, 4> &getAbstractScopesList() {
83    return AbstractScopesList;
84  }
85
86  /// findAbstractScope - Find an abstract scope or return NULL.
87  LexicalScope *findAbstractScope(const MDNode *N) {
88    return AbstractScopeMap.lookup(N);
89  }
90
91  /// findInlinedScope - Find an inlined scope for the given DebugLoc or return
92  /// NULL.
93  LexicalScope *findInlinedScope(DebugLoc DL) {
94    return InlinedLexicalScopeMap.lookup(DL);
95  }
96
97  /// findLexicalScope - Find regular lexical scope or return NULL.
98  LexicalScope *findLexicalScope(const MDNode *N) {
99    return LexicalScopeMap.lookup(N);
100  }
101
102  /// dump - Print data structures to dbgs().
103  void dump();
104
105private:
106
107  /// getOrCreateLexicalScope - Find lexical scope for the given DebugLoc. If
108  /// not available then create new lexical scope.
109  LexicalScope *getOrCreateLexicalScope(DebugLoc DL);
110
111  /// getOrCreateRegularScope - Find or create a regular lexical scope.
112  LexicalScope *getOrCreateRegularScope(MDNode *Scope);
113
114  /// getOrCreateInlinedScope - Find or create an inlined lexical scope.
115  LexicalScope *getOrCreateInlinedScope(MDNode *Scope, MDNode *InlinedAt);
116
117  /// getOrCreateAbstractScope - Find or create an abstract lexical scope.
118  LexicalScope *getOrCreateAbstractScope(const MDNode *N);
119
120  /// extractLexicalScopes - Extract instruction ranges for each lexical scopes
121  /// for the given machine function.
122  void extractLexicalScopes(SmallVectorImpl<InsnRange> &MIRanges,
123                            DenseMap<const MachineInstr *, LexicalScope *> &M);
124  void constructScopeNest(LexicalScope *Scope);
125  void assignInstructionRanges(SmallVectorImpl<InsnRange> &MIRanges,
126                             DenseMap<const MachineInstr *, LexicalScope *> &M);
127
128private:
129  const MachineFunction *MF;
130
131  /// LexicalScopeMap - Tracks the scopes in the current function.  Owns the
132  /// contained LexicalScope*s.
133  DenseMap<const MDNode *, LexicalScope *> LexicalScopeMap;
134
135  /// InlinedLexicalScopeMap - Tracks inlined function scopes in current function.
136  DenseMap<DebugLoc, LexicalScope *> InlinedLexicalScopeMap;
137
138  /// AbstractScopeMap - These scopes are  not included LexicalScopeMap.
139  /// AbstractScopes owns its LexicalScope*s.
140  DenseMap<const MDNode *, LexicalScope *> AbstractScopeMap;
141
142  /// AbstractScopesList - Tracks abstract scopes constructed while processing
143  /// a function.
144  SmallVector<LexicalScope *, 4>AbstractScopesList;
145
146  /// CurrentFnLexicalScope - Top level scope for the current function.
147  ///
148  LexicalScope *CurrentFnLexicalScope;
149};
150
151//===----------------------------------------------------------------------===//
152/// LexicalScope - This class is used to track scope information.
153///
154class LexicalScope {
155
156public:
157  LexicalScope(LexicalScope *P, const MDNode *D, const MDNode *I, bool A)
158    : Parent(P), Desc(D), InlinedAtLocation(I), AbstractScope(A),
159      LastInsn(0), FirstInsn(0), DFSIn(0), DFSOut(0), IndentLevel(0) {
160    if (Parent)
161      Parent->addChild(this);
162  }
163
164  virtual ~LexicalScope() {}
165
166  // Accessors.
167  LexicalScope *getParent() const               { return Parent; }
168  const MDNode *getDesc() const                 { return Desc; }
169  const MDNode *getInlinedAt() const            { return InlinedAtLocation; }
170  const MDNode *getScopeNode() const            { return Desc; }
171  bool isAbstractScope() const                  { return AbstractScope; }
172  SmallVector<LexicalScope *, 4> &getChildren() { return Children; }
173  SmallVector<InsnRange, 4> &getRanges()        { return Ranges; }
174
175  /// addChild - Add a child scope.
176  void addChild(LexicalScope *S) { Children.push_back(S); }
177
178  /// openInsnRange - This scope covers instruction range starting from MI.
179  void openInsnRange(const MachineInstr *MI) {
180    if (!FirstInsn)
181      FirstInsn = MI;
182
183    if (Parent)
184      Parent->openInsnRange(MI);
185  }
186
187  /// extendInsnRange - Extend the current instruction range covered by
188  /// this scope.
189  void extendInsnRange(const MachineInstr *MI) {
190    assert (FirstInsn && "MI Range is not open!");
191    LastInsn = MI;
192    if (Parent)
193      Parent->extendInsnRange(MI);
194  }
195
196  /// closeInsnRange - Create a range based on FirstInsn and LastInsn collected
197  /// until now. This is used when a new scope is encountered while walking
198  /// machine instructions.
199  void closeInsnRange(LexicalScope *NewScope = NULL) {
200    assert (LastInsn && "Last insn missing!");
201    Ranges.push_back(InsnRange(FirstInsn, LastInsn));
202    FirstInsn = NULL;
203    LastInsn = NULL;
204    // If Parent dominates NewScope then do not close Parent's instruction
205    // range.
206    if (Parent && (!NewScope || !Parent->dominates(NewScope)))
207      Parent->closeInsnRange(NewScope);
208  }
209
210  /// dominates - Return true if current scope dominsates given lexical scope.
211  bool dominates(const LexicalScope *S) {
212    if (S == this)
213      return true;
214    if (DFSIn < S->getDFSIn() && DFSOut > S->getDFSOut())
215      return true;
216    return false;
217  }
218
219  // Depth First Search support to walk and manipulate LexicalScope hierarchy.
220  unsigned getDFSOut() const            { return DFSOut; }
221  void setDFSOut(unsigned O)            { DFSOut = O; }
222  unsigned getDFSIn() const             { return DFSIn; }
223  void setDFSIn(unsigned I)             { DFSIn = I; }
224
225  /// dump - print lexical scope.
226  void dump() const;
227
228private:
229  LexicalScope *Parent;                          // Parent to this scope.
230  AssertingVH<const MDNode> Desc;                // Debug info descriptor.
231  AssertingVH<const MDNode> InlinedAtLocation;   // Location at which this
232                                                 // scope is inlined.
233  bool AbstractScope;                            // Abstract Scope
234  SmallVector<LexicalScope *, 4> Children;       // Scopes defined in scope.
235                                                 // Contents not owned.
236  SmallVector<InsnRange, 4> Ranges;
237
238  const MachineInstr *LastInsn;       // Last instruction of this scope.
239  const MachineInstr *FirstInsn;      // First instruction of this scope.
240  unsigned DFSIn, DFSOut;             // In & Out Depth use to determine
241                                      // scope nesting.
242  mutable unsigned IndentLevel;       // Private state for dump()
243};
244
245} // end llvm namespace
246
247#endif
248