1 //===- LexicalScopes.cpp - Collecting lexical scope info ------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements LexicalScopes analysis.
12 // This pass collects lexical scope information and maps machine instructions
13 // to respective lexical scopes.
15 //===----------------------------------------------------------------------===//
17 #include "llvm/CodeGen/LexicalScopes.h"
18 #include "llvm/CodeGen/MachineFunction.h"
19 #include "llvm/CodeGen/MachineInstr.h"
20 #include "llvm/IR/DebugInfo.h"
21 #include "llvm/IR/Function.h"
22 #include "llvm/Support/Debug.h"
23 #include "llvm/Support/ErrorHandling.h"
24 #include "llvm/Support/FormattedStream.h"
27 #define DEBUG_TYPE "lexicalscopes"
29 /// ~LexicalScopes - final cleanup after ourselves.
30 LexicalScopes::~LexicalScopes() { reset(); }
32 /// reset - Reset the instance so that it's prepared for another function.
33 void LexicalScopes::reset() {
35 CurrentFnLexicalScope = nullptr;
36 DeleteContainerSeconds(AbstractScopeMap);
37 InlinedLexicalScopeMap.clear();
38 AbstractScopesList.clear();
41 /// initialize - Scan machine function and constuct lexical scope nest.
42 void LexicalScopes::initialize(const MachineFunction &Fn) {
45 SmallVector<InsnRange, 4> MIRanges;
46 DenseMap<const MachineInstr *, LexicalScope *> MI2ScopeMap;
47 extractLexicalScopes(MIRanges, MI2ScopeMap);
48 if (CurrentFnLexicalScope) {
49 constructScopeNest(CurrentFnLexicalScope);
50 assignInstructionRanges(MIRanges, MI2ScopeMap);
54 /// extractLexicalScopes - Extract instruction ranges for each lexical scopes
55 /// for the given machine function.
56 void LexicalScopes::extractLexicalScopes(
57 SmallVectorImpl<InsnRange> &MIRanges,
58 DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
60 // Scan each instruction and create scopes. First build working set of scopes.
61 for (const auto &MBB : *MF) {
62 const MachineInstr *RangeBeginMI = nullptr;
63 const MachineInstr *PrevMI = nullptr;
65 for (const auto &MInsn : MBB) {
66 // Check if instruction has valid location information.
67 const DebugLoc MIDL = MInsn.getDebugLoc();
68 if (MIDL.isUnknown()) {
73 // If scope has not changed then skip this instruction.
79 // Ignore DBG_VALUE. It does not contribute to any instruction in output.
80 if (MInsn.isDebugValue())
84 // If we have already seen a beginning of an instruction range and
85 // current instruction scope does not match scope of first instruction
86 // in this range then create a new instruction range.
87 InsnRange R(RangeBeginMI, PrevMI);
88 MI2ScopeMap[RangeBeginMI] = getOrCreateLexicalScope(PrevDL);
89 MIRanges.push_back(R);
92 // This is a beginning of a new instruction range.
93 RangeBeginMI = &MInsn;
95 // Reset previous markers.
100 // Create last instruction range.
101 if (RangeBeginMI && PrevMI && !PrevDL.isUnknown()) {
102 InsnRange R(RangeBeginMI, PrevMI);
103 MIRanges.push_back(R);
104 MI2ScopeMap[RangeBeginMI] = getOrCreateLexicalScope(PrevDL);
109 /// findLexicalScope - Find lexical scope, either regular or inlined, for the
110 /// given DebugLoc. Return NULL if not found.
111 LexicalScope *LexicalScopes::findLexicalScope(DebugLoc DL) {
112 MDNode *Scope = nullptr;
113 MDNode *IA = nullptr;
114 DL.getScopeAndInlinedAt(Scope, IA, MF->getFunction()->getContext());
118 // The scope that we were created with could have an extra file - which
119 // isn't what we care about in this case.
120 DIDescriptor D = DIDescriptor(Scope);
121 if (D.isLexicalBlockFile())
122 Scope = DILexicalBlockFile(Scope).getScope();
125 return InlinedLexicalScopeMap.lookup(DebugLoc::getFromDILocation(IA));
126 auto I = LexicalScopeMap.find(Scope);
127 return I != LexicalScopeMap.end() ? I->second.get() : nullptr;
130 /// getOrCreateLexicalScope - Find lexical scope for the given DebugLoc. If
131 /// not available then create new lexical scope.
132 LexicalScope *LexicalScopes::getOrCreateLexicalScope(DebugLoc DL) {
133 MDNode *Scope = nullptr;
134 MDNode *InlinedAt = nullptr;
135 DL.getScopeAndInlinedAt(Scope, InlinedAt, MF->getFunction()->getContext());
138 // Create an abstract scope for inlined function.
139 getOrCreateAbstractScope(Scope);
140 // Create an inlined scope for inlined function.
141 return getOrCreateInlinedScope(Scope, InlinedAt);
144 return getOrCreateRegularScope(Scope);
147 /// getOrCreateRegularScope - Find or create a regular lexical scope.
148 LexicalScope *LexicalScopes::getOrCreateRegularScope(MDNode *Scope) {
149 DIDescriptor D = DIDescriptor(Scope);
150 if (D.isLexicalBlockFile()) {
151 Scope = DILexicalBlockFile(Scope).getScope();
152 D = DIDescriptor(Scope);
155 auto IterBool = LexicalScopeMap.insert(std::make_pair(Scope, std::unique_ptr<LexicalScope>()));
156 auto &MapValue = *IterBool.first;
157 if (!IterBool.second)
158 return MapValue.second.get();
160 LexicalScope *Parent = nullptr;
161 if (D.isLexicalBlock())
162 Parent = getOrCreateLexicalScope(DebugLoc::getFromDILexicalBlock(Scope));
163 MapValue.second = make_unique<LexicalScope>(Parent, DIDescriptor(Scope), nullptr, false);
164 if (!Parent && DIDescriptor(Scope).isSubprogram() &&
165 DISubprogram(Scope).describes(MF->getFunction()))
166 CurrentFnLexicalScope = MapValue.second.get();
168 return MapValue.second.get();
171 /// getOrCreateInlinedScope - Find or create an inlined lexical scope.
172 LexicalScope *LexicalScopes::getOrCreateInlinedScope(MDNode *Scope,
174 auto IterBool = LexicalScopeMap.insert(std::make_pair(InlinedAt, std::unique_ptr<LexicalScope>()));
175 auto &MapValue = *IterBool.first;
176 if (!IterBool.second)
177 return MapValue.second.get();
179 DebugLoc InlinedLoc = DebugLoc::getFromDILocation(InlinedAt);
180 MapValue.second = make_unique<LexicalScope>(getOrCreateLexicalScope(InlinedLoc),
181 DIDescriptor(Scope), InlinedAt, false);
182 InlinedLexicalScopeMap[InlinedLoc] = MapValue.second.get();
183 return MapValue.second.get();
186 /// getOrCreateAbstractScope - Find or create an abstract lexical scope.
187 LexicalScope *LexicalScopes::getOrCreateAbstractScope(const MDNode *N) {
188 assert(N && "Invalid Scope encoding!");
190 DIDescriptor Scope(N);
191 if (Scope.isLexicalBlockFile())
192 Scope = DILexicalBlockFile(Scope).getScope();
193 LexicalScope *AScope = AbstractScopeMap.lookup(N);
197 LexicalScope *Parent = nullptr;
198 if (Scope.isLexicalBlock()) {
199 DILexicalBlock DB(N);
200 DIDescriptor ParentDesc = DB.getContext();
201 Parent = getOrCreateAbstractScope(ParentDesc);
203 AScope = new LexicalScope(Parent, DIDescriptor(N), nullptr, true);
204 AbstractScopeMap[N] = AScope;
205 if (DIDescriptor(N).isSubprogram())
206 AbstractScopesList.push_back(AScope);
210 /// constructScopeNest
211 void LexicalScopes::constructScopeNest(LexicalScope *Scope) {
212 assert(Scope && "Unable to calculate scope dominance graph!");
213 SmallVector<LexicalScope *, 4> WorkStack;
214 WorkStack.push_back(Scope);
215 unsigned Counter = 0;
216 while (!WorkStack.empty()) {
217 LexicalScope *WS = WorkStack.back();
218 const SmallVectorImpl<LexicalScope *> &Children = WS->getChildren();
219 bool visitedChildren = false;
220 for (SmallVectorImpl<LexicalScope *>::const_iterator SI = Children.begin(),
223 LexicalScope *ChildScope = *SI;
224 if (!ChildScope->getDFSOut()) {
225 WorkStack.push_back(ChildScope);
226 visitedChildren = true;
227 ChildScope->setDFSIn(++Counter);
231 if (!visitedChildren) {
232 WorkStack.pop_back();
233 WS->setDFSOut(++Counter);
238 /// assignInstructionRanges - Find ranges of instructions covered by each
240 void LexicalScopes::assignInstructionRanges(
241 SmallVectorImpl<InsnRange> &MIRanges,
242 DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
244 LexicalScope *PrevLexicalScope = nullptr;
245 for (SmallVectorImpl<InsnRange>::const_iterator RI = MIRanges.begin(),
248 const InsnRange &R = *RI;
249 LexicalScope *S = MI2ScopeMap.lookup(R.first);
250 assert(S && "Lost LexicalScope for a machine instruction!");
251 if (PrevLexicalScope && !PrevLexicalScope->dominates(S))
252 PrevLexicalScope->closeInsnRange(S);
253 S->openInsnRange(R.first);
254 S->extendInsnRange(R.second);
255 PrevLexicalScope = S;
258 if (PrevLexicalScope)
259 PrevLexicalScope->closeInsnRange();
262 /// getMachineBasicBlocks - Populate given set using machine basic blocks which
263 /// have machine instructions that belong to lexical scope identified by
265 void LexicalScopes::getMachineBasicBlocks(
266 DebugLoc DL, SmallPtrSet<const MachineBasicBlock *, 4> &MBBs) {
268 LexicalScope *Scope = getOrCreateLexicalScope(DL);
272 if (Scope == CurrentFnLexicalScope) {
273 for (const auto &MBB : *MF)
278 SmallVectorImpl<InsnRange> &InsnRanges = Scope->getRanges();
279 for (SmallVectorImpl<InsnRange>::iterator I = InsnRanges.begin(),
280 E = InsnRanges.end();
283 MBBs.insert(R.first->getParent());
287 /// dominates - Return true if DebugLoc's lexical scope dominates at least one
288 /// machine instruction's lexical scope in a given machine basic block.
289 bool LexicalScopes::dominates(DebugLoc DL, MachineBasicBlock *MBB) {
290 LexicalScope *Scope = getOrCreateLexicalScope(DL);
294 // Current function scope covers all basic blocks in the function.
295 if (Scope == CurrentFnLexicalScope && MBB->getParent() == MF)
299 for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E;
301 DebugLoc IDL = I->getDebugLoc();
304 if (LexicalScope *IScope = getOrCreateLexicalScope(IDL))
305 if (Scope->dominates(IScope))
311 /// dump - Print data structures.
312 void LexicalScope::dump(unsigned Indent) const {
314 raw_ostream &err = dbgs();
316 err << "DFSIn: " << DFSIn << " DFSOut: " << DFSOut << "\n";
317 const MDNode *N = Desc;
321 err << std::string(Indent, ' ') << "Abstract Scope\n";
323 if (!Children.empty())
324 err << std::string(Indent + 2, ' ') << "Children ...\n";
325 for (unsigned i = 0, e = Children.size(); i != e; ++i)
326 if (Children[i] != this)
327 Children[i]->dump(Indent + 2);