1//===- LexicalScopes.cpp - Collecting lexical scope info --------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements LexicalScopes analysis.
10//
11// This pass collects lexical scope information and maps machine instructions
12// to respective lexical scopes.
13//
14//===----------------------------------------------------------------------===//
15
16#ifndef LLVM_CODEGEN_LEXICALSCOPES_H
17#define LLVM_CODEGEN_LEXICALSCOPES_H
18
19#include "llvm/ADT/ArrayRef.h"
20#include "llvm/ADT/DenseMap.h"
21#include "llvm/ADT/SmallPtrSet.h"
22#include "llvm/ADT/SmallVector.h"
23#include "llvm/IR/DebugInfoMetadata.h"
24#include <cassert>
25#include <unordered_map>
26#include <utility>
27
28namespace llvm {
29
30class MachineBasicBlock;
31class MachineFunction;
32class MachineInstr;
33class MDNode;
34
35//===----------------------------------------------------------------------===//
36/// InsnRange - This is used to track range of instructions with identical
37/// lexical scope.
38///
39using InsnRange = std::pair<const MachineInstr *, const MachineInstr *>;
40
41//===----------------------------------------------------------------------===//
42/// LexicalScope - This class is used to track scope information.
43///
44class LexicalScope {
45public:
46 LexicalScope(LexicalScope *P, const DILocalScope *D, const DILocation *I,
47 bool A)
48 : Parent(P), Desc(D), InlinedAtLocation(I), AbstractScope(A) {
49 assert(D);
50 assert(D->getSubprogram()->getUnit()->getEmissionKind() !=
51 DICompileUnit::NoDebug &&
52 "Don't build lexical scopes for non-debug locations");
53 assert(D->isResolved() && "Expected resolved node");
54 assert((!I || I->isResolved()) && "Expected resolved node");
55 if (Parent)
56 Parent->addChild(S: this);
57 }
58
59 // Accessors.
60 LexicalScope *getParent() const { return Parent; }
61 const MDNode *getDesc() const { return Desc; }
62 const DILocation *getInlinedAt() const { return InlinedAtLocation; }
63 const DILocalScope *getScopeNode() const { return Desc; }
64 bool isAbstractScope() const { return AbstractScope; }
65 SmallVectorImpl<LexicalScope *> &getChildren() { return Children; }
66 SmallVectorImpl<InsnRange> &getRanges() { return Ranges; }
67
68 /// addChild - Add a child scope.
69 void addChild(LexicalScope *S) { Children.push_back(Elt: S); }
70
71 /// openInsnRange - This scope covers instruction range starting from MI.
72 void openInsnRange(const MachineInstr *MI) {
73 if (!FirstInsn)
74 FirstInsn = MI;
75
76 if (Parent)
77 Parent->openInsnRange(MI);
78 }
79
80 /// extendInsnRange - Extend the current instruction range covered by
81 /// this scope.
82 void extendInsnRange(const MachineInstr *MI) {
83 assert(FirstInsn && "MI Range is not open!");
84 LastInsn = MI;
85 if (Parent)
86 Parent->extendInsnRange(MI);
87 }
88
89 /// closeInsnRange - Create a range based on FirstInsn and LastInsn collected
90 /// until now. This is used when a new scope is encountered while walking
91 /// machine instructions.
92 void closeInsnRange(LexicalScope *NewScope = nullptr) {
93 assert(LastInsn && "Last insn missing!");
94 Ranges.push_back(Elt: InsnRange(FirstInsn, LastInsn));
95 FirstInsn = nullptr;
96 LastInsn = nullptr;
97 // If Parent dominates NewScope then do not close Parent's instruction
98 // range.
99 if (Parent && (!NewScope || !Parent->dominates(S: NewScope)))
100 Parent->closeInsnRange(NewScope);
101 }
102
103 /// dominates - Return true if current scope dominates given lexical scope.
104 bool dominates(const LexicalScope *S) const {
105 if (S == this)
106 return true;
107 if (DFSIn < S->getDFSIn() && DFSOut > S->getDFSOut())
108 return true;
109 return false;
110 }
111
112 // Depth First Search support to walk and manipulate LexicalScope hierarchy.
113 unsigned getDFSOut() const { return DFSOut; }
114 void setDFSOut(unsigned O) { DFSOut = O; }
115 unsigned getDFSIn() const { return DFSIn; }
116 void setDFSIn(unsigned I) { DFSIn = I; }
117
118 /// dump - print lexical scope.
119 void dump(unsigned Indent = 0) const;
120
121private:
122 LexicalScope *Parent; // Parent to this scope.
123 const DILocalScope *Desc; // Debug info descriptor.
124 const DILocation *InlinedAtLocation; // Location at which this
125 // scope is inlined.
126 bool AbstractScope; // Abstract Scope
127 SmallVector<LexicalScope *, 4> Children; // Scopes defined in scope.
128 // Contents not owned.
129 SmallVector<InsnRange, 4> Ranges;
130
131 const MachineInstr *LastInsn = nullptr; // Last instruction of this scope.
132 const MachineInstr *FirstInsn = nullptr; // First instruction of this scope.
133 unsigned DFSIn = 0; // In & Out Depth use to determine scope nesting.
134 unsigned DFSOut = 0;
135};
136
137//===----------------------------------------------------------------------===//
138/// LexicalScopes - This class provides interface to collect and use lexical
139/// scoping information from machine instruction.
140///
141class LexicalScopes {
142public:
143 LexicalScopes() = default;
144
145 /// initialize - Scan machine function and constuct lexical scope nest, resets
146 /// the instance if necessary.
147 void initialize(const MachineFunction &);
148
149 /// releaseMemory - release memory.
150 void reset();
151
152 /// empty - Return true if there is any lexical scope information available.
153 bool empty() { return CurrentFnLexicalScope == nullptr; }
154
155 /// getCurrentFunctionScope - Return lexical scope for the current function.
156 LexicalScope *getCurrentFunctionScope() const {
157 return CurrentFnLexicalScope;
158 }
159
160 /// getMachineBasicBlocks - Populate given set using machine basic blocks
161 /// which have machine instructions that belong to lexical scope identified by
162 /// DebugLoc.
163 void getMachineBasicBlocks(const DILocation *DL,
164 SmallPtrSetImpl<const MachineBasicBlock *> &MBBs);
165
166 /// Return true if DebugLoc's lexical scope dominates at least one machine
167 /// instruction's lexical scope in a given machine basic block.
168 bool dominates(const DILocation *DL, MachineBasicBlock *MBB);
169
170 /// findLexicalScope - Find lexical scope, either regular or inlined, for the
171 /// given DebugLoc. Return NULL if not found.
172 LexicalScope *findLexicalScope(const DILocation *DL);
173
174 /// getAbstractScopesList - Return a reference to list of abstract scopes.
175 ArrayRef<LexicalScope *> getAbstractScopesList() const {
176 return AbstractScopesList;
177 }
178
179 /// findAbstractScope - Find an abstract scope or return null.
180 LexicalScope *findAbstractScope(const DILocalScope *N) {
181 auto I = AbstractScopeMap.find(x: N);
182 return I != AbstractScopeMap.end() ? &I->second : nullptr;
183 }
184
185 /// findInlinedScope - Find an inlined scope for the given scope/inlined-at.
186 LexicalScope *findInlinedScope(const DILocalScope *N, const DILocation *IA) {
187 auto I = InlinedLexicalScopeMap.find(x: std::make_pair(x&: N, y&: IA));
188 return I != InlinedLexicalScopeMap.end() ? &I->second : nullptr;
189 }
190
191 /// findLexicalScope - Find regular lexical scope or return null.
192 LexicalScope *findLexicalScope(const DILocalScope *N) {
193 auto I = LexicalScopeMap.find(x: N);
194 return I != LexicalScopeMap.end() ? &I->second : nullptr;
195 }
196
197 /// getOrCreateAbstractScope - Find or create an abstract lexical scope.
198 LexicalScope *getOrCreateAbstractScope(const DILocalScope *Scope);
199
200private:
201 /// getOrCreateLexicalScope - Find lexical scope for the given Scope/IA. If
202 /// not available then create new lexical scope.
203 LexicalScope *getOrCreateLexicalScope(const DILocalScope *Scope,
204 const DILocation *IA = nullptr);
205 LexicalScope *getOrCreateLexicalScope(const DILocation *DL) {
206 return DL ? getOrCreateLexicalScope(Scope: DL->getScope(), IA: DL->getInlinedAt())
207 : nullptr;
208 }
209
210 /// getOrCreateRegularScope - Find or create a regular lexical scope.
211 LexicalScope *getOrCreateRegularScope(const DILocalScope *Scope);
212
213 /// getOrCreateInlinedScope - Find or create an inlined lexical scope.
214 LexicalScope *getOrCreateInlinedScope(const DILocalScope *Scope,
215 const DILocation *InlinedAt);
216
217 /// extractLexicalScopes - Extract instruction ranges for each lexical scopes
218 /// for the given machine function.
219 void extractLexicalScopes(SmallVectorImpl<InsnRange> &MIRanges,
220 DenseMap<const MachineInstr *, LexicalScope *> &M);
221 void constructScopeNest(LexicalScope *Scope);
222 void
223 assignInstructionRanges(SmallVectorImpl<InsnRange> &MIRanges,
224 DenseMap<const MachineInstr *, LexicalScope *> &M);
225
226 const MachineFunction *MF = nullptr;
227
228 /// LexicalScopeMap - Tracks the scopes in the current function.
229 // Use an unordered_map to ensure value pointer validity over insertion.
230 std::unordered_map<const DILocalScope *, LexicalScope> LexicalScopeMap;
231
232 /// InlinedLexicalScopeMap - Tracks inlined function scopes in current
233 /// function.
234 std::unordered_map<std::pair<const DILocalScope *, const DILocation *>,
235 LexicalScope,
236 pair_hash<const DILocalScope *, const DILocation *>>
237 InlinedLexicalScopeMap;
238
239 /// AbstractScopeMap - These scopes are not included LexicalScopeMap.
240 // Use an unordered_map to ensure value pointer validity over insertion.
241 std::unordered_map<const DILocalScope *, LexicalScope> AbstractScopeMap;
242
243 /// AbstractScopesList - Tracks abstract scopes constructed while processing
244 /// a function.
245 SmallVector<LexicalScope *, 4> AbstractScopesList;
246
247 /// CurrentFnLexicalScope - Top level scope for the current function.
248 ///
249 LexicalScope *CurrentFnLexicalScope = nullptr;
250
251 /// Map a location to the set of basic blocks it dominates. This is a cache
252 /// for \ref LexicalScopes::getMachineBasicBlocks results.
253 using BlockSetT = SmallPtrSet<const MachineBasicBlock *, 4>;
254 DenseMap<const DILocation *, std::unique_ptr<BlockSetT>> DominatedBlocks;
255};
256
257} // end namespace llvm
258
259#endif // LLVM_CODEGEN_LEXICALSCOPES_H
260

source code of llvm/include/llvm/CodeGen/LexicalScopes.h