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) {
140 MDNode *Scope = nullptr;
141 MDNode *InlinedAt = nullptr;
142 DL.getScopeAndInlinedAt(Scope, InlinedAt, MF->getFunction()->getContext());
145 // Create an abstract scope for inlined function.
146 getOrCreateAbstractScope(Scope);
147 // Create an inlined scope for inlined function.
148 return getOrCreateInlinedScope(Scope, InlinedAt);
151 return getOrCreateRegularScope(Scope);
154 /// getOrCreateRegularScope - Find or create a regular lexical scope.
155 LexicalScope *LexicalScopes::getOrCreateRegularScope(MDNode *Scope) {
156 DIDescriptor D = DIDescriptor(Scope);
157 if (D.isLexicalBlockFile()) {
158 Scope = DILexicalBlockFile(Scope).getScope();
159 D = DIDescriptor(Scope);
162 auto I = LexicalScopeMap.find(Scope);
163 if (I != LexicalScopeMap.end())
166 LexicalScope *Parent = nullptr;
167 if (D.isLexicalBlock())
168 Parent = getOrCreateLexicalScope(DebugLoc::getFromDILexicalBlock(Scope));
169 // FIXME: Use forward_as_tuple instead of make_tuple, once MSVC2012
170 // compatibility is no longer required.
171 I = LexicalScopeMap.emplace(std::piecewise_construct, std::make_tuple(Scope),
172 std::make_tuple(Parent, DIDescriptor(Scope),
173 nullptr, false)).first;
175 if (!Parent && DIDescriptor(Scope).isSubprogram() &&
176 DISubprogram(Scope).describes(MF->getFunction()))
177 CurrentFnLexicalScope = &I->second;
182 /// getOrCreateInlinedScope - Find or create an inlined lexical scope.
183 LexicalScope *LexicalScopes::getOrCreateInlinedScope(MDNode *ScopeNode,
185 std::pair<const MDNode*, const MDNode*> P(ScopeNode, InlinedAt);
186 auto I = InlinedLexicalScopeMap.find(P);
187 if (I != InlinedLexicalScopeMap.end())
190 LexicalScope *Parent;
191 DILexicalBlock Scope(ScopeNode);
192 if (Scope.isLexicalBlock()) {
193 DILexicalBlock PB(Scope.getContext());
194 Parent = getOrCreateInlinedScope(PB, InlinedAt);
196 Parent = getOrCreateLexicalScope(DebugLoc::getFromDILocation(InlinedAt));
198 // FIXME: Use forward_as_tuple instead of make_tuple, once MSVC2012
199 // compatibility is no longer required.
200 I = InlinedLexicalScopeMap.emplace(std::piecewise_construct,
202 std::make_tuple(Parent, Scope, InlinedAt,
207 /// getOrCreateAbstractScope - Find or create an abstract lexical scope.
208 LexicalScope *LexicalScopes::getOrCreateAbstractScope(const MDNode *N) {
209 assert(N && "Invalid Scope encoding!");
211 DIDescriptor Scope(N);
212 if (Scope.isLexicalBlockFile())
213 Scope = DILexicalBlockFile(Scope).getScope();
214 auto I = AbstractScopeMap.find(N);
215 if (I != AbstractScopeMap.end())
218 LexicalScope *Parent = nullptr;
219 if (Scope.isLexicalBlock()) {
220 DILexicalBlock DB(N);
221 DIDescriptor ParentDesc = DB.getContext();
222 Parent = getOrCreateAbstractScope(ParentDesc);
224 I = AbstractScopeMap.emplace(std::piecewise_construct,
225 std::forward_as_tuple(N),
226 std::forward_as_tuple(Parent, DIDescriptor(N),
227 nullptr, true)).first;
228 if (DIDescriptor(N).isSubprogram())
229 AbstractScopesList.push_back(&I->second);
233 /// constructScopeNest
234 void LexicalScopes::constructScopeNest(LexicalScope *Scope) {
235 assert(Scope && "Unable to calculate scope dominance graph!");
236 SmallVector<LexicalScope *, 4> WorkStack;
237 WorkStack.push_back(Scope);
238 unsigned Counter = 0;
239 while (!WorkStack.empty()) {
240 LexicalScope *WS = WorkStack.back();
241 const SmallVectorImpl<LexicalScope *> &Children = WS->getChildren();
242 bool visitedChildren = false;
243 for (SmallVectorImpl<LexicalScope *>::const_iterator SI = Children.begin(),
246 LexicalScope *ChildScope = *SI;
247 if (!ChildScope->getDFSOut()) {
248 WorkStack.push_back(ChildScope);
249 visitedChildren = true;
250 ChildScope->setDFSIn(++Counter);
254 if (!visitedChildren) {
255 WorkStack.pop_back();
256 WS->setDFSOut(++Counter);
261 /// assignInstructionRanges - Find ranges of instructions covered by each
263 void LexicalScopes::assignInstructionRanges(
264 SmallVectorImpl<InsnRange> &MIRanges,
265 DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
267 LexicalScope *PrevLexicalScope = nullptr;
268 for (SmallVectorImpl<InsnRange>::const_iterator RI = MIRanges.begin(),
271 const InsnRange &R = *RI;
272 LexicalScope *S = MI2ScopeMap.lookup(R.first);
273 assert(S && "Lost LexicalScope for a machine instruction!");
274 if (PrevLexicalScope && !PrevLexicalScope->dominates(S))
275 PrevLexicalScope->closeInsnRange(S);
276 S->openInsnRange(R.first);
277 S->extendInsnRange(R.second);
278 PrevLexicalScope = S;
281 if (PrevLexicalScope)
282 PrevLexicalScope->closeInsnRange();
285 /// getMachineBasicBlocks - Populate given set using machine basic blocks which
286 /// have machine instructions that belong to lexical scope identified by
288 void LexicalScopes::getMachineBasicBlocks(
289 DebugLoc DL, SmallPtrSet<const MachineBasicBlock *, 4> &MBBs) {
291 LexicalScope *Scope = getOrCreateLexicalScope(DL);
295 if (Scope == CurrentFnLexicalScope) {
296 for (const auto &MBB : *MF)
301 SmallVectorImpl<InsnRange> &InsnRanges = Scope->getRanges();
302 for (SmallVectorImpl<InsnRange>::iterator I = InsnRanges.begin(),
303 E = InsnRanges.end();
306 MBBs.insert(R.first->getParent());
310 /// dominates - Return true if DebugLoc's lexical scope dominates at least one
311 /// machine instruction's lexical scope in a given machine basic block.
312 bool LexicalScopes::dominates(DebugLoc DL, MachineBasicBlock *MBB) {
313 LexicalScope *Scope = getOrCreateLexicalScope(DL);
317 // Current function scope covers all basic blocks in the function.
318 if (Scope == CurrentFnLexicalScope && MBB->getParent() == MF)
322 for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E;
324 DebugLoc IDL = I->getDebugLoc();
327 if (LexicalScope *IScope = getOrCreateLexicalScope(IDL))
328 if (Scope->dominates(IScope))
334 /// dump - Print data structures.
335 void LexicalScope::dump(unsigned Indent) const {
337 raw_ostream &err = dbgs();
339 err << "DFSIn: " << DFSIn << " DFSOut: " << DFSOut << "\n";
340 const MDNode *N = Desc;
344 err << std::string(Indent, ' ') << "Abstract Scope\n";
346 if (!Children.empty())
347 err << std::string(Indent + 2, ' ') << "Children ...\n";
348 for (unsigned i = 0, e = Children.size(); i != e; ++i)
349 if (Children[i] != this)
350 Children[i]->dump(Indent + 2);