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(
156 std::make_pair(Scope, std::unique_ptr<LexicalScope>()));
157 auto &MapValue = *IterBool.first;
158 if (!IterBool.second)
159 return MapValue.second.get();
161 LexicalScope *Parent = nullptr;
162 if (D.isLexicalBlock())
163 Parent = getOrCreateLexicalScope(DebugLoc::getFromDILexicalBlock(Scope));
165 make_unique<LexicalScope>(Parent, DIDescriptor(Scope), nullptr, false);
166 if (!Parent && DIDescriptor(Scope).isSubprogram() &&
167 DISubprogram(Scope).describes(MF->getFunction()))
168 CurrentFnLexicalScope = MapValue.second.get();
170 return MapValue.second.get();
173 /// getOrCreateInlinedScope - Find or create an inlined lexical scope.
174 LexicalScope *LexicalScopes::getOrCreateInlinedScope(MDNode *Scope,
176 auto IterBool = LexicalScopeMap.insert(
177 std::make_pair(InlinedAt, std::unique_ptr<LexicalScope>()));
178 auto &MapValue = *IterBool.first;
179 if (!IterBool.second)
180 return MapValue.second.get();
182 DebugLoc InlinedLoc = DebugLoc::getFromDILocation(InlinedAt);
184 make_unique<LexicalScope>(getOrCreateLexicalScope(InlinedLoc),
185 DIDescriptor(Scope), InlinedAt, false);
186 InlinedLexicalScopeMap[InlinedLoc] = MapValue.second.get();
187 return MapValue.second.get();
190 /// getOrCreateAbstractScope - Find or create an abstract lexical scope.
191 LexicalScope *LexicalScopes::getOrCreateAbstractScope(const MDNode *N) {
192 assert(N && "Invalid Scope encoding!");
194 DIDescriptor Scope(N);
195 if (Scope.isLexicalBlockFile())
196 Scope = DILexicalBlockFile(Scope).getScope();
197 LexicalScope *AScope = AbstractScopeMap.lookup(N);
201 LexicalScope *Parent = nullptr;
202 if (Scope.isLexicalBlock()) {
203 DILexicalBlock DB(N);
204 DIDescriptor ParentDesc = DB.getContext();
205 Parent = getOrCreateAbstractScope(ParentDesc);
207 AScope = new LexicalScope(Parent, DIDescriptor(N), nullptr, true);
208 AbstractScopeMap[N] = AScope;
209 if (DIDescriptor(N).isSubprogram())
210 AbstractScopesList.push_back(AScope);
214 /// constructScopeNest
215 void LexicalScopes::constructScopeNest(LexicalScope *Scope) {
216 assert(Scope && "Unable to calculate scope dominance graph!");
217 SmallVector<LexicalScope *, 4> WorkStack;
218 WorkStack.push_back(Scope);
219 unsigned Counter = 0;
220 while (!WorkStack.empty()) {
221 LexicalScope *WS = WorkStack.back();
222 const SmallVectorImpl<LexicalScope *> &Children = WS->getChildren();
223 bool visitedChildren = false;
224 for (SmallVectorImpl<LexicalScope *>::const_iterator SI = Children.begin(),
227 LexicalScope *ChildScope = *SI;
228 if (!ChildScope->getDFSOut()) {
229 WorkStack.push_back(ChildScope);
230 visitedChildren = true;
231 ChildScope->setDFSIn(++Counter);
235 if (!visitedChildren) {
236 WorkStack.pop_back();
237 WS->setDFSOut(++Counter);
242 /// assignInstructionRanges - Find ranges of instructions covered by each
244 void LexicalScopes::assignInstructionRanges(
245 SmallVectorImpl<InsnRange> &MIRanges,
246 DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
248 LexicalScope *PrevLexicalScope = nullptr;
249 for (SmallVectorImpl<InsnRange>::const_iterator RI = MIRanges.begin(),
252 const InsnRange &R = *RI;
253 LexicalScope *S = MI2ScopeMap.lookup(R.first);
254 assert(S && "Lost LexicalScope for a machine instruction!");
255 if (PrevLexicalScope && !PrevLexicalScope->dominates(S))
256 PrevLexicalScope->closeInsnRange(S);
257 S->openInsnRange(R.first);
258 S->extendInsnRange(R.second);
259 PrevLexicalScope = S;
262 if (PrevLexicalScope)
263 PrevLexicalScope->closeInsnRange();
266 /// getMachineBasicBlocks - Populate given set using machine basic blocks which
267 /// have machine instructions that belong to lexical scope identified by
269 void LexicalScopes::getMachineBasicBlocks(
270 DebugLoc DL, SmallPtrSet<const MachineBasicBlock *, 4> &MBBs) {
272 LexicalScope *Scope = getOrCreateLexicalScope(DL);
276 if (Scope == CurrentFnLexicalScope) {
277 for (const auto &MBB : *MF)
282 SmallVectorImpl<InsnRange> &InsnRanges = Scope->getRanges();
283 for (SmallVectorImpl<InsnRange>::iterator I = InsnRanges.begin(),
284 E = InsnRanges.end();
287 MBBs.insert(R.first->getParent());
291 /// dominates - Return true if DebugLoc's lexical scope dominates at least one
292 /// machine instruction's lexical scope in a given machine basic block.
293 bool LexicalScopes::dominates(DebugLoc DL, MachineBasicBlock *MBB) {
294 LexicalScope *Scope = getOrCreateLexicalScope(DL);
298 // Current function scope covers all basic blocks in the function.
299 if (Scope == CurrentFnLexicalScope && MBB->getParent() == MF)
303 for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E;
305 DebugLoc IDL = I->getDebugLoc();
308 if (LexicalScope *IScope = getOrCreateLexicalScope(IDL))
309 if (Scope->dominates(IScope))
315 /// dump - Print data structures.
316 void LexicalScope::dump(unsigned Indent) const {
318 raw_ostream &err = dbgs();
320 err << "DFSIn: " << DFSIn << " DFSOut: " << DFSOut << "\n";
321 const MDNode *N = Desc;
325 err << std::string(Indent, ' ') << "Abstract Scope\n";
327 if (!Children.empty())
328 err << std::string(Indent + 2, ' ') << "Children ...\n";
329 for (unsigned i = 0, e = Children.size(); i != e; ++i)
330 if (Children[i] != this)
331 Children[i]->dump(Indent + 2);