LexicalScopes.h revision 255f89faee13dc491cb64fbeae3c763e7e2ea4e6 
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/ADT/ArrayRef.h"
21#include "llvm/ADT/DenseMap.h"
22#include "llvm/ADT/SmallPtrSet.h"
23#include "llvm/ADT/SmallVector.h"
24#include "llvm/Metadata.h"
25#include "llvm/Support/DebugLoc.h"
26#include "llvm/Support/ValueHandle.h"
27#include <utility>
28namespace llvm {
29
30class MachineInstr;
31class MachineBasicBlock;
32class MachineFunction;
33class LexicalScope;
34
35//===----------------------------------------------------------------------===//
36/// InsnRange - This is used to track range of instructions with identical
37/// lexical scope.
38///
39typedef std::pair<const MachineInstr *, const MachineInstr *> InsnRange;
40
41//===----------------------------------------------------------------------===//
42/// LexicalScopes -  This class provides interface to collect and use lexical
43/// scoping information from machine instruction.
44///
45class LexicalScopes {
46public:
47  LexicalScopes() : MF(NULL),  CurrentFnLexicalScope(NULL) { }
48  virtual ~LexicalScopes();
49
50  /// initialize - Scan machine function and constuct lexical scope nest.
51  virtual void initialize(const MachineFunction &);
52
53  /// releaseMemory - release memory.
54  virtual void releaseMemory();
55
56  /// empty - Return true if there is any lexical scope information available.
57  bool empty() { return CurrentFnLexicalScope == NULL; }
58
59  /// isCurrentFunctionScope - Return true if given lexical scope represents
60  /// current function.
61  bool isCurrentFunctionScope(const LexicalScope *LS) {
62    return LS == CurrentFnLexicalScope;
63  }
64
65  /// getCurrentFunctionScope - Return lexical scope for the current function.
66  LexicalScope *getCurrentFunctionScope() const { return CurrentFnLexicalScope;}
67
68  /// getMachineBasicBlocks - Populate given set using machine basic blocks
69  /// which have machine instructions that belong to lexical scope identified by
70  /// DebugLoc.
71  void getMachineBasicBlocks(DebugLoc DL,
72                             SmallPtrSet<const MachineBasicBlock*, 4> &MBBs);
73
74  /// dominates - Return true if DebugLoc's lexical scope dominates at least one
75  /// machine instruction's lexical scope in a given machine basic block.
76  bool dominates(DebugLoc DL, MachineBasicBlock *MBB);
77
78  /// findLexicalScope - Find lexical scope, either regular or inlined, for the
79  /// given DebugLoc. Return NULL if not found.
80  LexicalScope *findLexicalScope(DebugLoc DL);
81
82  /// getAbstractScopesList - Return a reference to list of abstract scopes.
83  ArrayRef<LexicalScope *> getAbstractScopesList() const {
84    return AbstractScopesList;
85  }
86
87  /// findAbstractScope - Find an abstract scope or return NULL.
88  LexicalScope *findAbstractScope(const MDNode *N) {
89    return AbstractScopeMap.lookup(N);
90  }
91
92  /// findInlinedScope - Find an inlined scope for the given DebugLoc or return
93  /// NULL.
94  LexicalScope *findInlinedScope(DebugLoc DL) {
95    return InlinedLexicalScopeMap.lookup(DL);
96  }
97
98  /// findLexicalScope - Find regular lexical scope or return NULL.
99  LexicalScope *findLexicalScope(const MDNode *N) {
100    return LexicalScopeMap.lookup(N);
101  }
102
103  /// dump - Print data structures to dbgs().
104  void dump();
105
106private:
107
108  /// getOrCreateLexicalScope - Find lexical scope for the given DebugLoc. If
109  /// not available then create new lexical scope.
110  LexicalScope *getOrCreateLexicalScope(DebugLoc DL);
111
112  /// getOrCreateRegularScope - Find or create a regular lexical scope.
113  LexicalScope *getOrCreateRegularScope(MDNode *Scope);
114
115  /// getOrCreateInlinedScope - Find or create an inlined lexical scope.
116  LexicalScope *getOrCreateInlinedScope(MDNode *Scope, MDNode *InlinedAt);
117
118  /// getOrCreateAbstractScope - Find or create an abstract lexical scope.
119  LexicalScope *getOrCreateAbstractScope(const MDNode *N);
120
121  /// extractLexicalScopes - Extract instruction ranges for each lexical scopes
122  /// for the given machine function.
123  void extractLexicalScopes(SmallVectorImpl<InsnRange> &MIRanges,
124                            DenseMap<const MachineInstr *, LexicalScope *> &M);
125  void constructScopeNest(LexicalScope *Scope);
126  void assignInstructionRanges(SmallVectorImpl<InsnRange> &MIRanges,
127                             DenseMap<const MachineInstr *, LexicalScope *> &M);
128
129private:
130  const MachineFunction *MF;
131
132  /// LexicalScopeMap - Tracks the scopes in the current function.  Owns the
133  /// contained LexicalScope*s.
134  DenseMap<const MDNode *, LexicalScope *> LexicalScopeMap;
135
136  /// InlinedLexicalScopeMap - Tracks inlined function scopes in current function.
137  DenseMap<DebugLoc, LexicalScope *> InlinedLexicalScopeMap;
138
139  /// AbstractScopeMap - These scopes are  not included LexicalScopeMap.
140  /// AbstractScopes owns its LexicalScope*s.
141  DenseMap<const MDNode *, LexicalScope *> AbstractScopeMap;
142
143  /// AbstractScopesList - Tracks abstract scopes constructed while processing
144  /// a function.
145  SmallVector<LexicalScope *, 4>AbstractScopesList;
146
147  /// CurrentFnLexicalScope - Top level scope for the current function.
148  ///
149  LexicalScope *CurrentFnLexicalScope;
150};
151
152//===----------------------------------------------------------------------===//
153/// LexicalScope - This class is used to track scope information.
154///
155class LexicalScope {
156  virtual void anchor();
157
158public:
159  LexicalScope(LexicalScope *P, const MDNode *D, const MDNode *I, bool A)
160    : Parent(P), Desc(D), InlinedAtLocation(I), AbstractScope(A),
161      LastInsn(0), FirstInsn(0), DFSIn(0), DFSOut(0) {
162#ifndef NDEBUG
163    IndentLevel = 0;
164#endif
165    if (Parent)
166      Parent->addChild(this);
167  }
168
169  virtual ~LexicalScope() {}
170
171  // Accessors.
172  LexicalScope *getParent() const               { return Parent; }
173  const MDNode *getDesc() const                 { return Desc; }
174  const MDNode *getInlinedAt() const            { return InlinedAtLocation; }
175  const MDNode *getScopeNode() const            { return Desc; }
176  bool isAbstractScope() const                  { return AbstractScope; }
177  SmallVector<LexicalScope *, 4> &getChildren() { return Children; }
178  SmallVector<InsnRange, 4> &getRanges()        { return Ranges; }
179
180  /// addChild - Add a child scope.
181  void addChild(LexicalScope *S) { Children.push_back(S); }
182
183  /// openInsnRange - This scope covers instruction range starting from MI.
184  void openInsnRange(const MachineInstr *MI) {
185    if (!FirstInsn)
186      FirstInsn = MI;
187
188    if (Parent)
189      Parent->openInsnRange(MI);
190  }
191
192  /// extendInsnRange - Extend the current instruction range covered by
193  /// this scope.
194  void extendInsnRange(const MachineInstr *MI) {
195    assert (FirstInsn && "MI Range is not open!");
196    LastInsn = MI;
197    if (Parent)
198      Parent->extendInsnRange(MI);
199  }
200
201  /// closeInsnRange - Create a range based on FirstInsn and LastInsn collected
202  /// until now. This is used when a new scope is encountered while walking
203  /// machine instructions.
204  void closeInsnRange(LexicalScope *NewScope = NULL) {
205    assert (LastInsn && "Last insn missing!");
206    Ranges.push_back(InsnRange(FirstInsn, LastInsn));
207    FirstInsn = NULL;
208    LastInsn = NULL;
209    // If Parent dominates NewScope then do not close Parent's instruction
210    // range.
211    if (Parent && (!NewScope || !Parent->dominates(NewScope)))
212      Parent->closeInsnRange(NewScope);
213  }
214
215  /// dominates - Return true if current scope dominates given lexical scope.
216  bool dominates(const LexicalScope *S) const {
217    if (S == this)
218      return true;
219    if (DFSIn < S->getDFSIn() && DFSOut > S->getDFSOut())
220      return true;
221    return false;
222  }
223
224  // Depth First Search support to walk and manipulate LexicalScope hierarchy.
225  unsigned getDFSOut() const            { return DFSOut; }
226  void setDFSOut(unsigned O)            { DFSOut = O; }
227  unsigned getDFSIn() const             { return DFSIn; }
228  void setDFSIn(unsigned I)             { DFSIn = I; }
229
230  /// dump - print lexical scope.
231  void dump() const;
232
233private:
234  LexicalScope *Parent;                          // Parent to this scope.
235  AssertingVH<const MDNode> Desc;                // Debug info descriptor.
236  AssertingVH<const MDNode> InlinedAtLocation;   // Location at which this
237                                                 // scope is inlined.
238  bool AbstractScope;                            // Abstract Scope
239  SmallVector<LexicalScope *, 4> Children;       // Scopes defined in scope.
240                                                 // Contents not owned.
241  SmallVector<InsnRange, 4> Ranges;
242
243  const MachineInstr *LastInsn;       // Last instruction of this scope.
244  const MachineInstr *FirstInsn;      // First instruction of this scope.
245  unsigned DFSIn, DFSOut;             // In & Out Depth use to determine
246                                      // scope nesting.
247#ifndef NDEBUG
248  mutable unsigned IndentLevel;       // Private state for dump()
249#endif
250};
251
252} // end llvm namespace
253
254#endif
255