Remove static global GCNames from Function.cpp and move it to the Context
[oota-llvm.git] / lib / CodeGen / LexicalScopes.cpp
1 //===- LexicalScopes.cpp - Collecting lexical scope info ------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements LexicalScopes analysis.
11 //
12 // This pass collects lexical scope information and maps machine instructions
13 // to respective lexical scopes.
14 //
15 //===----------------------------------------------------------------------===//
16
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"
25 using namespace llvm;
26
27 #define DEBUG_TYPE "lexicalscopes"
28
29 /// reset - Reset the instance so that it's prepared for another function.
30 void LexicalScopes::reset() {
31   MF = nullptr;
32   CurrentFnLexicalScope = nullptr;
33   LexicalScopeMap.clear();
34   AbstractScopeMap.clear();
35   InlinedLexicalScopeMap.clear();
36   AbstractScopesList.clear();
37 }
38
39 /// initialize - Scan machine function and constuct lexical scope nest.
40 void LexicalScopes::initialize(const MachineFunction &Fn) {
41   reset();
42   MF = &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);
49   }
50 }
51
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) {
57
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;
62     const DILocation *PrevDL = nullptr;
63     for (const auto &MInsn : MBB) {
64       // Check if instruction has valid location information.
65       const DILocation *MIDL = MInsn.getDebugLoc();
66       if (!MIDL) {
67         PrevMI = &MInsn;
68         continue;
69       }
70
71       // If scope has not changed then skip this instruction.
72       if (MIDL == PrevDL) {
73         PrevMI = &MInsn;
74         continue;
75       }
76
77       // Ignore DBG_VALUE. It does not contribute to any instruction in output.
78       if (MInsn.isDebugValue())
79         continue;
80
81       if (RangeBeginMI) {
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);
88       }
89
90       // This is a beginning of a new instruction range.
91       RangeBeginMI = &MInsn;
92
93       // Reset previous markers.
94       PrevMI = &MInsn;
95       PrevDL = MIDL;
96     }
97
98     // Create last instruction range.
99     if (RangeBeginMI && PrevMI && PrevDL) {
100       InsnRange R(RangeBeginMI, PrevMI);
101       MIRanges.push_back(R);
102       MI2ScopeMap[RangeBeginMI] = getOrCreateLexicalScope(PrevDL);
103     }
104   }
105 }
106
107 /// findLexicalScope - Find lexical scope, either regular or inlined, for the
108 /// given DebugLoc. Return NULL if not found.
109 LexicalScope *LexicalScopes::findLexicalScope(const DILocation *DL) {
110   DILocalScope *Scope = DL->getScope();
111   if (!Scope)
112     return nullptr;
113
114   // The scope that we were created with could have an extra file - which
115   // isn't what we care about in this case.
116   if (auto *File = dyn_cast<DILexicalBlockFile>(Scope))
117     Scope = File->getScope();
118
119   if (auto *IA = DL->getInlinedAt()) {
120     auto I = InlinedLexicalScopeMap.find(std::make_pair(Scope, IA));
121     return I != InlinedLexicalScopeMap.end() ? &I->second : nullptr;
122   }
123   return findLexicalScope(Scope);
124 }
125
126 /// getOrCreateLexicalScope - Find lexical scope for the given DebugLoc. If
127 /// not available then create new lexical scope.
128 LexicalScope *LexicalScopes::getOrCreateLexicalScope(const DILocalScope *Scope,
129                                                      const DILocation *IA) {
130   if (IA) {
131     // Create an abstract scope for inlined function.
132     getOrCreateAbstractScope(Scope);
133     // Create an inlined scope for inlined function.
134     return getOrCreateInlinedScope(Scope, IA);
135   }
136
137   return getOrCreateRegularScope(Scope);
138 }
139
140 /// getOrCreateRegularScope - Find or create a regular lexical scope.
141 LexicalScope *
142 LexicalScopes::getOrCreateRegularScope(const DILocalScope *Scope) {
143   if (auto *File = dyn_cast<DILexicalBlockFile>(Scope))
144     Scope = File->getScope();
145
146   auto I = LexicalScopeMap.find(Scope);
147   if (I != LexicalScopeMap.end())
148     return &I->second;
149
150   // FIXME: Should the following dyn_cast be DILexicalBlock?
151   LexicalScope *Parent = nullptr;
152   if (auto *Block = dyn_cast<DILexicalBlockBase>(Scope))
153     Parent = getOrCreateLexicalScope(Block->getScope());
154   I = LexicalScopeMap.emplace(std::piecewise_construct,
155                               std::forward_as_tuple(Scope),
156                               std::forward_as_tuple(Parent, Scope, nullptr,
157                                                     false)).first;
158
159   if (!Parent) {
160     assert(cast<DISubprogram>(Scope)->describes(MF->getFunction()));
161     assert(!CurrentFnLexicalScope);
162     CurrentFnLexicalScope = &I->second;
163   }
164
165   return &I->second;
166 }
167
168 /// getOrCreateInlinedScope - Find or create an inlined lexical scope.
169 LexicalScope *
170 LexicalScopes::getOrCreateInlinedScope(const DILocalScope *Scope,
171                                        const DILocation *InlinedAt) {
172   std::pair<const DILocalScope *, const DILocation *> P(Scope, InlinedAt);
173   auto I = InlinedLexicalScopeMap.find(P);
174   if (I != InlinedLexicalScopeMap.end())
175     return &I->second;
176
177   LexicalScope *Parent;
178   if (auto *Block = dyn_cast<DILexicalBlockBase>(Scope))
179     Parent = getOrCreateInlinedScope(Block->getScope(), InlinedAt);
180   else
181     Parent = getOrCreateLexicalScope(InlinedAt);
182
183   I = InlinedLexicalScopeMap.emplace(std::piecewise_construct,
184                                      std::forward_as_tuple(P),
185                                      std::forward_as_tuple(Parent, Scope,
186                                                            InlinedAt, false))
187           .first;
188   return &I->second;
189 }
190
191 /// getOrCreateAbstractScope - Find or create an abstract lexical scope.
192 LexicalScope *
193 LexicalScopes::getOrCreateAbstractScope(const DILocalScope *Scope) {
194   assert(Scope && "Invalid Scope encoding!");
195
196   if (auto *File = dyn_cast<DILexicalBlockFile>(Scope))
197     Scope = File->getScope();
198   auto I = AbstractScopeMap.find(Scope);
199   if (I != AbstractScopeMap.end())
200     return &I->second;
201
202   // FIXME: Should the following isa be DILexicalBlock?
203   LexicalScope *Parent = nullptr;
204   if (auto *Block = dyn_cast<DILexicalBlockBase>(Scope))
205     Parent = getOrCreateAbstractScope(Block->getScope());
206
207   I = AbstractScopeMap.emplace(std::piecewise_construct,
208                                std::forward_as_tuple(Scope),
209                                std::forward_as_tuple(Parent, Scope,
210                                                      nullptr, true)).first;
211   if (isa<DISubprogram>(Scope))
212     AbstractScopesList.push_back(&I->second);
213   return &I->second;
214 }
215
216 /// constructScopeNest
217 void LexicalScopes::constructScopeNest(LexicalScope *Scope) {
218   assert(Scope && "Unable to calculate scope dominance graph!");
219   SmallVector<LexicalScope *, 4> WorkStack;
220   WorkStack.push_back(Scope);
221   unsigned Counter = 0;
222   while (!WorkStack.empty()) {
223     LexicalScope *WS = WorkStack.back();
224     const SmallVectorImpl<LexicalScope *> &Children = WS->getChildren();
225     bool visitedChildren = false;
226     for (SmallVectorImpl<LexicalScope *>::const_iterator SI = Children.begin(),
227                                                          SE = Children.end();
228          SI != SE; ++SI) {
229       LexicalScope *ChildScope = *SI;
230       if (!ChildScope->getDFSOut()) {
231         WorkStack.push_back(ChildScope);
232         visitedChildren = true;
233         ChildScope->setDFSIn(++Counter);
234         break;
235       }
236     }
237     if (!visitedChildren) {
238       WorkStack.pop_back();
239       WS->setDFSOut(++Counter);
240     }
241   }
242 }
243
244 /// assignInstructionRanges - Find ranges of instructions covered by each
245 /// lexical scope.
246 void LexicalScopes::assignInstructionRanges(
247     SmallVectorImpl<InsnRange> &MIRanges,
248     DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
249
250   LexicalScope *PrevLexicalScope = nullptr;
251   for (SmallVectorImpl<InsnRange>::const_iterator RI = MIRanges.begin(),
252                                                   RE = MIRanges.end();
253        RI != RE; ++RI) {
254     const InsnRange &R = *RI;
255     LexicalScope *S = MI2ScopeMap.lookup(R.first);
256     assert(S && "Lost LexicalScope for a machine instruction!");
257     if (PrevLexicalScope && !PrevLexicalScope->dominates(S))
258       PrevLexicalScope->closeInsnRange(S);
259     S->openInsnRange(R.first);
260     S->extendInsnRange(R.second);
261     PrevLexicalScope = S;
262   }
263
264   if (PrevLexicalScope)
265     PrevLexicalScope->closeInsnRange();
266 }
267
268 /// getMachineBasicBlocks - Populate given set using machine basic blocks which
269 /// have machine instructions that belong to lexical scope identified by
270 /// DebugLoc.
271 void LexicalScopes::getMachineBasicBlocks(
272     const DILocation *DL, SmallPtrSetImpl<const MachineBasicBlock *> &MBBs) {
273   MBBs.clear();
274   LexicalScope *Scope = getOrCreateLexicalScope(DL);
275   if (!Scope)
276     return;
277
278   if (Scope == CurrentFnLexicalScope) {
279     for (const auto &MBB : *MF)
280       MBBs.insert(&MBB);
281     return;
282   }
283
284   SmallVectorImpl<InsnRange> &InsnRanges = Scope->getRanges();
285   for (SmallVectorImpl<InsnRange>::iterator I = InsnRanges.begin(),
286                                             E = InsnRanges.end();
287        I != E; ++I) {
288     InsnRange &R = *I;
289     MBBs.insert(R.first->getParent());
290   }
291 }
292
293 /// dominates - Return true if DebugLoc's lexical scope dominates at least one
294 /// machine instruction's lexical scope in a given machine basic block.
295 bool LexicalScopes::dominates(const DILocation *DL, MachineBasicBlock *MBB) {
296   LexicalScope *Scope = getOrCreateLexicalScope(DL);
297   if (!Scope)
298     return false;
299
300   // Current function scope covers all basic blocks in the function.
301   if (Scope == CurrentFnLexicalScope && MBB->getParent() == MF)
302     return true;
303
304   bool Result = false;
305   for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E;
306        ++I) {
307     if (const DILocation *IDL = I->getDebugLoc())
308       if (LexicalScope *IScope = getOrCreateLexicalScope(IDL))
309         if (Scope->dominates(IScope))
310           return true;
311   }
312   return Result;
313 }
314
315 /// dump - Print data structures.
316 void LexicalScope::dump(unsigned Indent) const {
317 #ifndef NDEBUG
318   raw_ostream &err = dbgs();
319   err.indent(Indent);
320   err << "DFSIn: " << DFSIn << " DFSOut: " << DFSOut << "\n";
321   const MDNode *N = Desc;
322   err.indent(Indent);
323   N->dump();
324   if (AbstractScope)
325     err << std::string(Indent, ' ') << "Abstract Scope\n";
326
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);
332 #endif
333 }