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 /// reset - Reset the instance so that it's prepared for another function.
30 void LexicalScopes::reset() {
32 CurrentFnLexicalScope = nullptr;
33 LexicalScopeMap.clear();
34 AbstractScopeMap.clear();
35 InlinedLexicalScopeMap.clear();
36 AbstractScopesList.clear();
39 /// initialize - Scan machine function and constuct lexical scope nest.
40 void LexicalScopes::initialize(const MachineFunction &Fn) {
43 SmallVector<InsnRange, 4> MIRanges;
44 DenseMap<const MachineInstr *, LexicalScope *> MI2ScopeMap;
45 extractLexicalScopes(MIRanges, MI2ScopeMap);
46 if (CurrentFnLexicalScope) {
47 constructScopeNest(CurrentFnLexicalScope);
48 assignInstructionRanges(MIRanges, MI2ScopeMap);
52 /// extractLexicalScopes - Extract instruction ranges for each lexical scopes
53 /// for the given machine function.
54 void LexicalScopes::extractLexicalScopes(
55 SmallVectorImpl<InsnRange> &MIRanges,
56 DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
58 // Scan each instruction and create scopes. First build working set of scopes.
59 for (const auto &MBB : *MF) {
60 const MachineInstr *RangeBeginMI = nullptr;
61 const MachineInstr *PrevMI = nullptr;
63 for (const auto &MInsn : MBB) {
64 // Check if instruction has valid location information.
65 const DebugLoc MIDL = MInsn.getDebugLoc();
66 if (MIDL.isUnknown()) {
71 // If scope has not changed then skip this instruction.
77 // Ignore DBG_VALUE. It does not contribute to any instruction in output.
78 if (MInsn.isDebugValue())
82 // If we have already seen a beginning of an instruction range and
83 // current instruction scope does not match scope of first instruction
84 // in this range then create a new instruction range.
85 InsnRange R(RangeBeginMI, PrevMI);
86 MI2ScopeMap[RangeBeginMI] = getOrCreateLexicalScope(PrevDL);
87 MIRanges.push_back(R);
90 // This is a beginning of a new instruction range.
91 RangeBeginMI = &MInsn;
93 // Reset previous markers.
98 // Create last instruction range.
99 if (RangeBeginMI && PrevMI && !PrevDL.isUnknown()) {
100 InsnRange R(RangeBeginMI, PrevMI);
101 MIRanges.push_back(R);
102 MI2ScopeMap[RangeBeginMI] = getOrCreateLexicalScope(PrevDL);
107 /// findLexicalScope - Find lexical scope, either regular or inlined, for the
108 /// given DebugLoc. Return NULL if not found.
109 LexicalScope *LexicalScopes::findLexicalScope(DebugLoc DL) {
110 MDNode *Scope = nullptr;
111 MDNode *IA = nullptr;
112 DL.getScopeAndInlinedAt(Scope, IA, MF->getFunction()->getContext());
116 // The scope that we were created with could have an extra file - which
117 // isn't what we care about in this case.
118 DIDescriptor D = DIDescriptor(Scope);
119 if (D.isLexicalBlockFile())
120 Scope = DILexicalBlockFile(Scope).getScope();
123 auto I = InlinedLexicalScopeMap.find(std::make_pair(Scope, IA));
124 return I != InlinedLexicalScopeMap.end() ? &I->second : nullptr;
126 return findLexicalScope(Scope);
129 /// getOrCreateLexicalScope - Find lexical scope for the given DebugLoc. If
130 /// not available then create new lexical scope.
131 LexicalScope *LexicalScopes::getOrCreateLexicalScope(DebugLoc DL) {
134 MDNode *Scope = nullptr;
135 MDNode *InlinedAt = nullptr;
136 DL.getScopeAndInlinedAt(Scope, InlinedAt, MF->getFunction()->getContext());
139 // Create an abstract scope for inlined function.
140 getOrCreateAbstractScope(Scope);
141 // Create an inlined scope for inlined function.
142 return getOrCreateInlinedScope(Scope, InlinedAt);
145 return getOrCreateRegularScope(Scope);
148 /// getOrCreateRegularScope - Find or create a regular lexical scope.
149 LexicalScope *LexicalScopes::getOrCreateRegularScope(MDNode *Scope) {
150 DIDescriptor D = DIDescriptor(Scope);
151 if (D.isLexicalBlockFile()) {
152 Scope = DILexicalBlockFile(Scope).getScope();
153 D = DIDescriptor(Scope);
156 auto I = LexicalScopeMap.find(Scope);
157 if (I != LexicalScopeMap.end())
160 LexicalScope *Parent = nullptr;
161 if (D.isLexicalBlock())
162 Parent = getOrCreateLexicalScope(DebugLoc::getFromDILexicalBlock(Scope));
163 I = LexicalScopeMap.emplace(std::piecewise_construct,
164 std::forward_as_tuple(Scope),
165 std::forward_as_tuple(Parent, DIDescriptor(Scope),
166 nullptr, false)).first;
169 assert(DIDescriptor(Scope).isSubprogram());
170 assert(DISubprogram(Scope).describes(MF->getFunction()));
171 assert(!CurrentFnLexicalScope);
172 CurrentFnLexicalScope = &I->second;
178 /// getOrCreateInlinedScope - Find or create an inlined lexical scope.
179 LexicalScope *LexicalScopes::getOrCreateInlinedScope(MDNode *ScopeNode,
181 std::pair<const MDNode*, const MDNode*> P(ScopeNode, InlinedAt);
182 auto I = InlinedLexicalScopeMap.find(P);
183 if (I != InlinedLexicalScopeMap.end())
186 LexicalScope *Parent;
187 DILexicalBlock Scope(ScopeNode);
188 if (Scope.isSubprogram())
189 Parent = getOrCreateLexicalScope(DebugLoc::getFromDILocation(InlinedAt));
191 Parent = getOrCreateInlinedScope(Scope.getContext(), InlinedAt);
193 I = InlinedLexicalScopeMap.emplace(std::piecewise_construct,
194 std::forward_as_tuple(P),
195 std::forward_as_tuple(Parent, Scope,
201 /// getOrCreateAbstractScope - Find or create an abstract lexical scope.
202 LexicalScope *LexicalScopes::getOrCreateAbstractScope(const MDNode *N) {
203 assert(N && "Invalid Scope encoding!");
205 DIDescriptor Scope(N);
206 if (Scope.isLexicalBlockFile())
207 Scope = DILexicalBlockFile(Scope).getScope();
208 auto I = AbstractScopeMap.find(Scope);
209 if (I != AbstractScopeMap.end())
212 LexicalScope *Parent = nullptr;
213 if (Scope.isLexicalBlock()) {
214 DILexicalBlock DB(Scope);
215 DIDescriptor ParentDesc = DB.getContext();
216 Parent = getOrCreateAbstractScope(ParentDesc);
218 I = AbstractScopeMap.emplace(std::piecewise_construct,
219 std::forward_as_tuple(Scope),
220 std::forward_as_tuple(Parent, Scope,
221 nullptr, true)).first;
222 if (Scope.isSubprogram())
223 AbstractScopesList.push_back(&I->second);
227 /// constructScopeNest
228 void LexicalScopes::constructScopeNest(LexicalScope *Scope) {
229 assert(Scope && "Unable to calculate scope dominance graph!");
230 SmallVector<LexicalScope *, 4> WorkStack;
231 WorkStack.push_back(Scope);
232 unsigned Counter = 0;
233 while (!WorkStack.empty()) {
234 LexicalScope *WS = WorkStack.back();
235 const SmallVectorImpl<LexicalScope *> &Children = WS->getChildren();
236 bool visitedChildren = false;
237 for (SmallVectorImpl<LexicalScope *>::const_iterator SI = Children.begin(),
240 LexicalScope *ChildScope = *SI;
241 if (!ChildScope->getDFSOut()) {
242 WorkStack.push_back(ChildScope);
243 visitedChildren = true;
244 ChildScope->setDFSIn(++Counter);
248 if (!visitedChildren) {
249 WorkStack.pop_back();
250 WS->setDFSOut(++Counter);
255 /// assignInstructionRanges - Find ranges of instructions covered by each
257 void LexicalScopes::assignInstructionRanges(
258 SmallVectorImpl<InsnRange> &MIRanges,
259 DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
261 LexicalScope *PrevLexicalScope = nullptr;
262 for (SmallVectorImpl<InsnRange>::const_iterator RI = MIRanges.begin(),
265 const InsnRange &R = *RI;
266 LexicalScope *S = MI2ScopeMap.lookup(R.first);
267 assert(S && "Lost LexicalScope for a machine instruction!");
268 if (PrevLexicalScope && !PrevLexicalScope->dominates(S))
269 PrevLexicalScope->closeInsnRange(S);
270 S->openInsnRange(R.first);
271 S->extendInsnRange(R.second);
272 PrevLexicalScope = S;
275 if (PrevLexicalScope)
276 PrevLexicalScope->closeInsnRange();
279 /// getMachineBasicBlocks - Populate given set using machine basic blocks which
280 /// have machine instructions that belong to lexical scope identified by
282 void LexicalScopes::getMachineBasicBlocks(
283 DebugLoc DL, SmallPtrSetImpl<const MachineBasicBlock *> &MBBs) {
285 LexicalScope *Scope = getOrCreateLexicalScope(DL);
289 if (Scope == CurrentFnLexicalScope) {
290 for (const auto &MBB : *MF)
295 SmallVectorImpl<InsnRange> &InsnRanges = Scope->getRanges();
296 for (SmallVectorImpl<InsnRange>::iterator I = InsnRanges.begin(),
297 E = InsnRanges.end();
300 MBBs.insert(R.first->getParent());
304 /// dominates - Return true if DebugLoc's lexical scope dominates at least one
305 /// machine instruction's lexical scope in a given machine basic block.
306 bool LexicalScopes::dominates(DebugLoc DL, MachineBasicBlock *MBB) {
307 LexicalScope *Scope = getOrCreateLexicalScope(DL);
311 // Current function scope covers all basic blocks in the function.
312 if (Scope == CurrentFnLexicalScope && MBB->getParent() == MF)
316 for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E;
318 DebugLoc IDL = I->getDebugLoc();
321 if (LexicalScope *IScope = getOrCreateLexicalScope(IDL))
322 if (Scope->dominates(IScope))
328 /// dump - Print data structures.
329 void LexicalScope::dump(unsigned Indent) const {
331 raw_ostream &err = dbgs();
333 err << "DFSIn: " << DFSIn << " DFSOut: " << DFSOut << "\n";
334 const MDNode *N = Desc;
338 err << std::string(Indent, ' ') << "Abstract Scope\n";
340 if (!Children.empty())
341 err << std::string(Indent + 2, ' ') << "Children ...\n";
342 for (unsigned i = 0, e = Children.size(); i != e; ++i)
343 if (Children[i] != this)
344 Children[i]->dump(Indent + 2);