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/STLExtras.h"
23#include "llvm/ADT/SmallPtrSet.h"
24#include "llvm/ADT/SmallVector.h"
25#include "llvm/IR/DebugLoc.h"
26#include "llvm/IR/DebugInfoMetadata.h"
27#include "llvm/IR/ValueHandle.h"
28#include <unordered_map>
29#include <utility>
30namespace llvm {
31
32class MachineInstr;
33class MachineBasicBlock;
34class MachineFunction;
35
36//===----------------------------------------------------------------------===//
37/// InsnRange - This is used to track range of instructions with identical
38/// lexical scope.
39///
40typedef std::pair<const MachineInstr *, const MachineInstr *> InsnRange;
41
42//===----------------------------------------------------------------------===//
43/// LexicalScope - This class is used to track scope information.
44///
45class LexicalScope {
46
47public:
48  LexicalScope(LexicalScope *P, const DILocalScope *D, const DILocation *I,
49               bool A)
50      : Parent(P), Desc(D), InlinedAtLocation(I), AbstractScope(A),
51        LastInsn(nullptr), FirstInsn(nullptr), DFSIn(0), DFSOut(0) {
52    assert((!D || D->isResolved()) && "Expected resolved node");
53    assert((!I || I->isResolved()) && "Expected resolved node");
54    if (Parent)
55      Parent->addChild(this);
56  }
57
58  // Accessors.
59  LexicalScope *getParent() const { return Parent; }
60  const MDNode *getDesc() const { return Desc; }
61  const DILocation *getInlinedAt() const { return InlinedAtLocation; }
62  const DILocalScope *getScopeNode() const { return Desc; }
63  bool isAbstractScope() const { return AbstractScope; }
64  SmallVectorImpl<LexicalScope *> &getChildren() { return Children; }
65  SmallVectorImpl<InsnRange> &getRanges() { return Ranges; }
66
67  /// addChild - Add a child scope.
68  void addChild(LexicalScope *S) { Children.push_back(S); }
69
70  /// openInsnRange - This scope covers instruction range starting from MI.
71  void openInsnRange(const MachineInstr *MI) {
72    if (!FirstInsn)
73      FirstInsn = MI;
74
75    if (Parent)
76      Parent->openInsnRange(MI);
77  }
78
79  /// extendInsnRange - Extend the current instruction range covered by
80  /// this scope.
81  void extendInsnRange(const MachineInstr *MI) {
82    assert(FirstInsn && "MI Range is not open!");
83    LastInsn = MI;
84    if (Parent)
85      Parent->extendInsnRange(MI);
86  }
87
88  /// closeInsnRange - Create a range based on FirstInsn and LastInsn collected
89  /// until now. This is used when a new scope is encountered while walking
90  /// machine instructions.
91  void closeInsnRange(LexicalScope *NewScope = nullptr) {
92    assert(LastInsn && "Last insn missing!");
93    Ranges.push_back(InsnRange(FirstInsn, LastInsn));
94    FirstInsn = nullptr;
95    LastInsn = nullptr;
96    // If Parent dominates NewScope then do not close Parent's instruction
97    // range.
98    if (Parent && (!NewScope || !Parent->dominates(NewScope)))
99      Parent->closeInsnRange(NewScope);
100  }
101
102  /// dominates - Return true if current scope dominates given lexical scope.
103  bool dominates(const LexicalScope *S) const {
104    if (S == this)
105      return true;
106    if (DFSIn < S->getDFSIn() && DFSOut > S->getDFSOut())
107      return true;
108    return false;
109  }
110
111  // Depth First Search support to walk and manipulate LexicalScope hierarchy.
112  unsigned getDFSOut() const { return DFSOut; }
113  void setDFSOut(unsigned O) { DFSOut = O; }
114  unsigned getDFSIn() const { return DFSIn; }
115  void setDFSIn(unsigned I) { DFSIn = I; }
116
117  /// dump - print lexical scope.
118  void dump(unsigned Indent = 0) const;
119
120private:
121  LexicalScope *Parent;                        // Parent to this scope.
122  const DILocalScope *Desc;                    // Debug info descriptor.
123  const DILocation *InlinedAtLocation;         // Location at which this
124                                               // scope is inlined.
125  bool AbstractScope;                          // Abstract Scope
126  SmallVector<LexicalScope *, 4> Children;     // Scopes defined in scope.
127                                               // Contents not owned.
128  SmallVector<InsnRange, 4> Ranges;
129
130  const MachineInstr *LastInsn;  // Last instruction of this scope.
131  const MachineInstr *FirstInsn; // First instruction of this scope.
132  unsigned DFSIn, DFSOut;        // In & Out Depth use to determine
133                                 // scope nesting.
134};
135
136//===----------------------------------------------------------------------===//
137/// LexicalScopes -  This class provides interface to collect and use lexical
138/// scoping information from machine instruction.
139///
140class LexicalScopes {
141public:
142  LexicalScopes() : MF(nullptr), CurrentFnLexicalScope(nullptr) {}
143
144  /// initialize - Scan machine function and constuct lexical scope nest, resets
145  /// the instance if necessary.
146  void initialize(const MachineFunction &);
147
148  /// releaseMemory - release memory.
149  void reset();
150
151  /// empty - Return true if there is any lexical scope information available.
152  bool empty() { return CurrentFnLexicalScope == nullptr; }
153
154  /// getCurrentFunctionScope - Return lexical scope for the current function.
155  LexicalScope *getCurrentFunctionScope() const {
156    return CurrentFnLexicalScope;
157  }
158
159  /// getMachineBasicBlocks - Populate given set using machine basic blocks
160  /// which have machine instructions that belong to lexical scope identified by
161  /// DebugLoc.
162  void getMachineBasicBlocks(const DILocation *DL,
163                             SmallPtrSetImpl<const MachineBasicBlock *> &MBBs);
164
165  /// dominates - Return true if DebugLoc's lexical scope dominates at least one
166  /// machine instruction's lexical scope in a given machine basic block.
167  bool dominates(const DILocation *DL, MachineBasicBlock *MBB);
168
169  /// findLexicalScope - Find lexical scope, either regular or inlined, for the
170  /// given DebugLoc. Return NULL if not found.
171  LexicalScope *findLexicalScope(const DILocation *DL);
172
173  /// getAbstractScopesList - Return a reference to list of abstract scopes.
174  ArrayRef<LexicalScope *> getAbstractScopesList() const {
175    return AbstractScopesList;
176  }
177
178  /// findAbstractScope - Find an abstract scope or return null.
179  LexicalScope *findAbstractScope(const DILocalScope *N) {
180    auto I = AbstractScopeMap.find(N);
181    return I != AbstractScopeMap.end() ? &I->second : nullptr;
182  }
183
184  /// findInlinedScope - Find an inlined scope for the given scope/inlined-at.
185  LexicalScope *findInlinedScope(const DILocalScope *N, const DILocation *IA) {
186    auto I = InlinedLexicalScopeMap.find(std::make_pair(N, IA));
187    return I != InlinedLexicalScopeMap.end() ? &I->second : nullptr;
188  }
189
190  /// findLexicalScope - Find regular lexical scope or return null.
191  LexicalScope *findLexicalScope(const DILocalScope *N) {
192    auto I = LexicalScopeMap.find(N);
193    return I != LexicalScopeMap.end() ? &I->second : nullptr;
194  }
195
196  /// dump - Print data structures to dbgs().
197  void dump();
198
199  /// getOrCreateAbstractScope - Find or create an abstract lexical scope.
200  LexicalScope *getOrCreateAbstractScope(const DILocalScope *Scope);
201
202private:
203  /// getOrCreateLexicalScope - Find lexical scope for the given Scope/IA. If
204  /// not available then create new lexical scope.
205  LexicalScope *getOrCreateLexicalScope(const DILocalScope *Scope,
206                                        const DILocation *IA = nullptr);
207  LexicalScope *getOrCreateLexicalScope(const DILocation *DL) {
208    return DL ? getOrCreateLexicalScope(DL->getScope(), DL->getInlinedAt())
209              : nullptr;
210  }
211
212  /// getOrCreateRegularScope - Find or create a regular lexical scope.
213  LexicalScope *getOrCreateRegularScope(const DILocalScope *Scope);
214
215  /// getOrCreateInlinedScope - Find or create an inlined lexical scope.
216  LexicalScope *getOrCreateInlinedScope(const DILocalScope *Scope,
217                                        const DILocation *InlinedAt);
218
219  /// extractLexicalScopes - Extract instruction ranges for each lexical scopes
220  /// for the given machine function.
221  void extractLexicalScopes(SmallVectorImpl<InsnRange> &MIRanges,
222                            DenseMap<const MachineInstr *, LexicalScope *> &M);
223  void constructScopeNest(LexicalScope *Scope);
224  void
225  assignInstructionRanges(SmallVectorImpl<InsnRange> &MIRanges,
226                          DenseMap<const MachineInstr *, LexicalScope *> &M);
227
228private:
229  const MachineFunction *MF;
230
231  /// LexicalScopeMap - Tracks the scopes in the current function.
232  // Use an unordered_map to ensure value pointer validity over insertion.
233  std::unordered_map<const DILocalScope *, LexicalScope> LexicalScopeMap;
234
235  /// InlinedLexicalScopeMap - Tracks inlined function scopes in current
236  /// function.
237  std::unordered_map<std::pair<const DILocalScope *, const DILocation *>,
238                     LexicalScope,
239                     pair_hash<const DILocalScope *, const DILocation *>>
240      InlinedLexicalScopeMap;
241
242  /// AbstractScopeMap - These scopes are  not included LexicalScopeMap.
243  // Use an unordered_map to ensure value pointer validity over insertion.
244  std::unordered_map<const DILocalScope *, LexicalScope> AbstractScopeMap;
245
246  /// AbstractScopesList - Tracks abstract scopes constructed while processing
247  /// a function.
248  SmallVector<LexicalScope *, 4> AbstractScopesList;
249
250  /// CurrentFnLexicalScope - Top level scope for the current function.
251  ///
252  LexicalScope *CurrentFnLexicalScope;
253};
254
255} // end llvm namespace
256
257#endif
258