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 LexicalScope *LexicalScopes::findInlinedScope(DebugLoc DL) {
108 MDNode *Scope = nullptr;
109 MDNode *IA = nullptr;
110 DL.getScopeAndInlinedAt(Scope, IA, MF->getFunction()->getContext());
111 auto I = InlinedLexicalScopeMap.find(std::make_pair(Scope, IA));
112 return I != InlinedLexicalScopeMap.end() ? &I->second : nullptr;
115 /// findLexicalScope - Find lexical scope, either regular or inlined, for the
116 /// given DebugLoc. Return NULL if not found.
117 LexicalScope *LexicalScopes::findLexicalScope(DebugLoc DL) {
118 MDNode *Scope = nullptr;
119 MDNode *IA = nullptr;
120 DL.getScopeAndInlinedAt(Scope, IA, MF->getFunction()->getContext());
124 // The scope that we were created with could have an extra file - which
125 // isn't what we care about in this case.
126 DIDescriptor D = DIDescriptor(Scope);
127 if (D.isLexicalBlockFile())
128 Scope = DILexicalBlockFile(Scope).getScope();
131 auto I = InlinedLexicalScopeMap.find(std::make_pair(Scope, IA));
132 return I != InlinedLexicalScopeMap.end() ? &I->second : nullptr;
134 return findLexicalScope(Scope);
137 /// getOrCreateLexicalScope - Find lexical scope for the given DebugLoc. If
138 /// not available then create new lexical scope.
139 LexicalScope *LexicalScopes::getOrCreateLexicalScope(DebugLoc DL) {
142 MDNode *Scope = nullptr;
143 MDNode *InlinedAt = nullptr;
144 DL.getScopeAndInlinedAt(Scope, InlinedAt, MF->getFunction()->getContext());
147 // Create an abstract scope for inlined function.
148 getOrCreateAbstractScope(Scope);
149 // Create an inlined scope for inlined function.
150 return getOrCreateInlinedScope(Scope, InlinedAt);
153 return getOrCreateRegularScope(Scope);
156 /// getOrCreateRegularScope - Find or create a regular lexical scope.
157 LexicalScope *LexicalScopes::getOrCreateRegularScope(MDNode *Scope) {
158 DIDescriptor D = DIDescriptor(Scope);
159 if (D.isLexicalBlockFile()) {
160 Scope = DILexicalBlockFile(Scope).getScope();
161 D = DIDescriptor(Scope);
164 auto I = LexicalScopeMap.find(Scope);
165 if (I != LexicalScopeMap.end())
168 LexicalScope *Parent = nullptr;
169 if (D.isLexicalBlock())
170 Parent = getOrCreateLexicalScope(DebugLoc::getFromDILexicalBlock(Scope));
171 I = LexicalScopeMap.emplace(std::piecewise_construct,
172 std::forward_as_tuple(Scope),
173 std::forward_as_tuple(Parent, DIDescriptor(Scope),
174 nullptr, false)).first;
177 assert(DIDescriptor(Scope).isSubprogram());
178 assert(DISubprogram(Scope).describes(MF->getFunction()));
179 assert(!CurrentFnLexicalScope);
180 CurrentFnLexicalScope = &I->second;
186 /// getOrCreateInlinedScope - Find or create an inlined lexical scope.
187 LexicalScope *LexicalScopes::getOrCreateInlinedScope(MDNode *ScopeNode,
189 std::pair<const MDNode*, const MDNode*> P(ScopeNode, InlinedAt);
190 auto I = InlinedLexicalScopeMap.find(P);
191 if (I != InlinedLexicalScopeMap.end())
194 LexicalScope *Parent;
195 DILexicalBlock Scope(ScopeNode);
196 if (Scope.isSubprogram())
197 Parent = getOrCreateLexicalScope(DebugLoc::getFromDILocation(InlinedAt));
199 Parent = getOrCreateInlinedScope(Scope.getContext(), InlinedAt);
201 I = InlinedLexicalScopeMap.emplace(std::piecewise_construct,
202 std::forward_as_tuple(P),
203 std::forward_as_tuple(Parent, Scope,
209 /// getOrCreateAbstractScope - Find or create an abstract lexical scope.
210 LexicalScope *LexicalScopes::getOrCreateAbstractScope(const MDNode *N) {
211 assert(N && "Invalid Scope encoding!");
213 DIDescriptor Scope(N);
214 if (Scope.isLexicalBlockFile())
215 Scope = DILexicalBlockFile(Scope).getScope();
216 auto I = AbstractScopeMap.find(Scope);
217 if (I != AbstractScopeMap.end())
220 LexicalScope *Parent = nullptr;
221 if (Scope.isLexicalBlock()) {
222 DILexicalBlock DB(Scope);
223 DIDescriptor ParentDesc = DB.getContext();
224 Parent = getOrCreateAbstractScope(ParentDesc);
226 I = AbstractScopeMap.emplace(std::piecewise_construct,
227 std::forward_as_tuple(Scope),
228 std::forward_as_tuple(Parent, Scope,
229 nullptr, true)).first;
230 if (Scope.isSubprogram())
231 AbstractScopesList.push_back(&I->second);
235 /// constructScopeNest
236 void LexicalScopes::constructScopeNest(LexicalScope *Scope) {
237 assert(Scope && "Unable to calculate scope dominance graph!");
238 SmallVector<LexicalScope *, 4> WorkStack;
239 WorkStack.push_back(Scope);
240 unsigned Counter = 0;
241 while (!WorkStack.empty()) {
242 LexicalScope *WS = WorkStack.back();
243 const SmallVectorImpl<LexicalScope *> &Children = WS->getChildren();
244 bool visitedChildren = false;
245 for (SmallVectorImpl<LexicalScope *>::const_iterator SI = Children.begin(),
248 LexicalScope *ChildScope = *SI;
249 if (!ChildScope->getDFSOut()) {
250 WorkStack.push_back(ChildScope);
251 visitedChildren = true;
252 ChildScope->setDFSIn(++Counter);
256 if (!visitedChildren) {
257 WorkStack.pop_back();
258 WS->setDFSOut(++Counter);
263 /// assignInstructionRanges - Find ranges of instructions covered by each
265 void LexicalScopes::assignInstructionRanges(
266 SmallVectorImpl<InsnRange> &MIRanges,
267 DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
269 LexicalScope *PrevLexicalScope = nullptr;
270 for (SmallVectorImpl<InsnRange>::const_iterator RI = MIRanges.begin(),
273 const InsnRange &R = *RI;
274 LexicalScope *S = MI2ScopeMap.lookup(R.first);
275 assert(S && "Lost LexicalScope for a machine instruction!");
276 if (PrevLexicalScope && !PrevLexicalScope->dominates(S))
277 PrevLexicalScope->closeInsnRange(S);
278 S->openInsnRange(R.first);
279 S->extendInsnRange(R.second);
280 PrevLexicalScope = S;
283 if (PrevLexicalScope)
284 PrevLexicalScope->closeInsnRange();
287 /// getMachineBasicBlocks - Populate given set using machine basic blocks which
288 /// have machine instructions that belong to lexical scope identified by
290 void LexicalScopes::getMachineBasicBlocks(
291 DebugLoc DL, SmallPtrSetImpl<const MachineBasicBlock *> &MBBs) {
293 LexicalScope *Scope = getOrCreateLexicalScope(DL);
297 if (Scope == CurrentFnLexicalScope) {
298 for (const auto &MBB : *MF)
303 SmallVectorImpl<InsnRange> &InsnRanges = Scope->getRanges();
304 for (SmallVectorImpl<InsnRange>::iterator I = InsnRanges.begin(),
305 E = InsnRanges.end();
308 MBBs.insert(R.first->getParent());
312 /// dominates - Return true if DebugLoc's lexical scope dominates at least one
313 /// machine instruction's lexical scope in a given machine basic block.
314 bool LexicalScopes::dominates(DebugLoc DL, MachineBasicBlock *MBB) {
315 LexicalScope *Scope = getOrCreateLexicalScope(DL);
319 // Current function scope covers all basic blocks in the function.
320 if (Scope == CurrentFnLexicalScope && MBB->getParent() == MF)
324 for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E;
326 DebugLoc IDL = I->getDebugLoc();
329 if (LexicalScope *IScope = getOrCreateLexicalScope(IDL))
330 if (Scope->dominates(IScope))
336 /// dump - Print data structures.
337 void LexicalScope::dump(unsigned Indent) const {
339 raw_ostream &err = dbgs();
341 err << "DFSIn: " << DFSIn << " DFSOut: " << DFSOut << "\n";
342 const MDNode *N = Desc;
346 err << std::string(Indent, ' ') << "Abstract Scope\n";
348 if (!Children.empty())
349 err << std::string(Indent + 2, ' ') << "Children ...\n";
350 for (unsigned i = 0, e = Children.size(); i != e; ++i)
351 if (Children[i] != this)
352 Children[i]->dump(Indent + 2);