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 #define DEBUG_TYPE "lexicalscopes"
18 #include "llvm/CodeGen/LexicalScopes.h"
19 #include "llvm/DebugInfo.h"
20 #include "llvm/Function.h"
21 #include "llvm/CodeGen/MachineFunction.h"
22 #include "llvm/CodeGen/MachineInstr.h"
23 #include "llvm/Support/Debug.h"
24 #include "llvm/Support/ErrorHandling.h"
25 #include "llvm/Support/FormattedStream.h"
26 using namespace llvm;
27
~LexicalScopes()28 LexicalScopes::~LexicalScopes() {
29 releaseMemory();
30 }
31
32 /// releaseMemory - release memory.
releaseMemory()33 void LexicalScopes::releaseMemory() {
34 MF = NULL;
35 CurrentFnLexicalScope = NULL;
36 DeleteContainerSeconds(LexicalScopeMap);
37 DeleteContainerSeconds(AbstractScopeMap);
38 InlinedLexicalScopeMap.clear();
39 AbstractScopesList.clear();
40 }
41
42 /// initialize - Scan machine function and constuct lexical scope nest.
initialize(const MachineFunction & Fn)43 void LexicalScopes::initialize(const MachineFunction &Fn) {
44 releaseMemory();
45 MF = &Fn;
46 SmallVector<InsnRange, 4> MIRanges;
47 DenseMap<const MachineInstr *, LexicalScope *> MI2ScopeMap;
48 extractLexicalScopes(MIRanges, MI2ScopeMap);
49 if (CurrentFnLexicalScope) {
50 constructScopeNest(CurrentFnLexicalScope);
51 assignInstructionRanges(MIRanges, MI2ScopeMap);
52 }
53 }
54
55 /// extractLexicalScopes - Extract instruction ranges for each lexical scopes
56 /// for the given machine function.
57 void LexicalScopes::
extractLexicalScopes(SmallVectorImpl<InsnRange> & MIRanges,DenseMap<const MachineInstr *,LexicalScope * > & MI2ScopeMap)58 extractLexicalScopes(SmallVectorImpl<InsnRange> &MIRanges,
59 DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
60
61 // Scan each instruction and create scopes. First build working set of scopes.
62 for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
63 I != E; ++I) {
64 const MachineInstr *RangeBeginMI = NULL;
65 const MachineInstr *PrevMI = NULL;
66 DebugLoc PrevDL;
67 for (MachineBasicBlock::const_iterator II = I->begin(), IE = I->end();
68 II != IE; ++II) {
69 const MachineInstr *MInsn = II;
70
71 // Check if instruction has valid location information.
72 const DebugLoc MIDL = MInsn->getDebugLoc();
73 if (MIDL.isUnknown()) {
74 PrevMI = MInsn;
75 continue;
76 }
77
78 // If scope has not changed then skip this instruction.
79 if (MIDL == PrevDL) {
80 PrevMI = MInsn;
81 continue;
82 }
83
84 // Ignore DBG_VALUE. It does not contribute to any instruction in output.
85 if (MInsn->isDebugValue())
86 continue;
87
88 if (RangeBeginMI) {
89 // If we have already seen a beginning of an instruction range and
90 // current instruction scope does not match scope of first instruction
91 // in this range then create a new instruction range.
92 InsnRange R(RangeBeginMI, PrevMI);
93 MI2ScopeMap[RangeBeginMI] = getOrCreateLexicalScope(PrevDL);
94 MIRanges.push_back(R);
95 }
96
97 // This is a beginning of a new instruction range.
98 RangeBeginMI = MInsn;
99
100 // Reset previous markers.
101 PrevMI = MInsn;
102 PrevDL = MIDL;
103 }
104
105 // Create last instruction range.
106 if (RangeBeginMI && PrevMI && !PrevDL.isUnknown()) {
107 InsnRange R(RangeBeginMI, PrevMI);
108 MIRanges.push_back(R);
109 MI2ScopeMap[RangeBeginMI] = getOrCreateLexicalScope(PrevDL);
110 }
111 }
112 }
113
114 /// findLexicalScope - Find lexical scope, either regular or inlined, for the
115 /// given DebugLoc. Return NULL if not found.
findLexicalScope(DebugLoc DL)116 LexicalScope *LexicalScopes::findLexicalScope(DebugLoc DL) {
117 MDNode *Scope = NULL;
118 MDNode *IA = NULL;
119 DL.getScopeAndInlinedAt(Scope, IA, MF->getFunction()->getContext());
120 if (!Scope) return NULL;
121
122 // The scope that we were created with could have an extra file - which
123 // isn't what we care about in this case.
124 DIDescriptor D = DIDescriptor(Scope);
125 if (D.isLexicalBlockFile())
126 Scope = DILexicalBlockFile(Scope).getScope();
127
128 if (IA)
129 return InlinedLexicalScopeMap.lookup(DebugLoc::getFromDILocation(IA));
130 return LexicalScopeMap.lookup(Scope);
131 }
132
133 /// getOrCreateLexicalScope - Find lexical scope for the given DebugLoc. If
134 /// not available then create new lexical scope.
getOrCreateLexicalScope(DebugLoc DL)135 LexicalScope *LexicalScopes::getOrCreateLexicalScope(DebugLoc DL) {
136 MDNode *Scope = NULL;
137 MDNode *InlinedAt = NULL;
138 DL.getScopeAndInlinedAt(Scope, InlinedAt, MF->getFunction()->getContext());
139
140 if (InlinedAt) {
141 // Create an abstract scope for inlined function.
142 getOrCreateAbstractScope(Scope);
143 // Create an inlined scope for inlined function.
144 return getOrCreateInlinedScope(Scope, InlinedAt);
145 }
146
147 return getOrCreateRegularScope(Scope);
148 }
149
150 /// getOrCreateRegularScope - Find or create a regular lexical scope.
getOrCreateRegularScope(MDNode * Scope)151 LexicalScope *LexicalScopes::getOrCreateRegularScope(MDNode *Scope) {
152 DIDescriptor D = DIDescriptor(Scope);
153 if (D.isLexicalBlockFile()) {
154 Scope = DILexicalBlockFile(Scope).getScope();
155 D = DIDescriptor(Scope);
156 }
157
158 LexicalScope *WScope = LexicalScopeMap.lookup(Scope);
159 if (WScope)
160 return WScope;
161
162 LexicalScope *Parent = NULL;
163 if (D.isLexicalBlock())
164 Parent = getOrCreateLexicalScope(DebugLoc::getFromDILexicalBlock(Scope));
165 WScope = new LexicalScope(Parent, DIDescriptor(Scope), NULL, false);
166 LexicalScopeMap.insert(std::make_pair(Scope, WScope));
167 if (!Parent && DIDescriptor(Scope).isSubprogram()
168 && DISubprogram(Scope).describes(MF->getFunction()))
169 CurrentFnLexicalScope = WScope;
170
171 return WScope;
172 }
173
174 /// getOrCreateInlinedScope - Find or create an inlined lexical scope.
getOrCreateInlinedScope(MDNode * Scope,MDNode * InlinedAt)175 LexicalScope *LexicalScopes::getOrCreateInlinedScope(MDNode *Scope,
176 MDNode *InlinedAt) {
177 LexicalScope *InlinedScope = LexicalScopeMap.lookup(InlinedAt);
178 if (InlinedScope)
179 return InlinedScope;
180
181 DebugLoc InlinedLoc = DebugLoc::getFromDILocation(InlinedAt);
182 InlinedScope = new LexicalScope(getOrCreateLexicalScope(InlinedLoc),
183 DIDescriptor(Scope), InlinedAt, false);
184 InlinedLexicalScopeMap[InlinedLoc] = InlinedScope;
185 LexicalScopeMap[InlinedAt] = InlinedScope;
186 return InlinedScope;
187 }
188
189 /// getOrCreateAbstractScope - Find or create an abstract lexical scope.
getOrCreateAbstractScope(const MDNode * N)190 LexicalScope *LexicalScopes::getOrCreateAbstractScope(const MDNode *N) {
191 assert(N && "Invalid Scope encoding!");
192
193 DIDescriptor Scope(N);
194 if (Scope.isLexicalBlockFile())
195 Scope = DILexicalBlockFile(Scope).getScope();
196 LexicalScope *AScope = AbstractScopeMap.lookup(N);
197 if (AScope)
198 return AScope;
199
200 LexicalScope *Parent = NULL;
201 if (Scope.isLexicalBlock()) {
202 DILexicalBlock DB(N);
203 DIDescriptor ParentDesc = DB.getContext();
204 Parent = getOrCreateAbstractScope(ParentDesc);
205 }
206 AScope = new LexicalScope(Parent, DIDescriptor(N), NULL, true);
207 AbstractScopeMap[N] = AScope;
208 if (DIDescriptor(N).isSubprogram())
209 AbstractScopesList.push_back(AScope);
210 return AScope;
211 }
212
213 /// constructScopeNest
constructScopeNest(LexicalScope * Scope)214 void LexicalScopes::constructScopeNest(LexicalScope *Scope) {
215 assert (Scope && "Unable to calculate scop edominance graph!");
216 SmallVector<LexicalScope *, 4> WorkStack;
217 WorkStack.push_back(Scope);
218 unsigned Counter = 0;
219 while (!WorkStack.empty()) {
220 LexicalScope *WS = WorkStack.back();
221 const SmallVector<LexicalScope *, 4> &Children = WS->getChildren();
222 bool visitedChildren = false;
223 for (SmallVector<LexicalScope *, 4>::const_iterator SI = Children.begin(),
224 SE = Children.end(); SI != SE; ++SI) {
225 LexicalScope *ChildScope = *SI;
226 if (!ChildScope->getDFSOut()) {
227 WorkStack.push_back(ChildScope);
228 visitedChildren = true;
229 ChildScope->setDFSIn(++Counter);
230 break;
231 }
232 }
233 if (!visitedChildren) {
234 WorkStack.pop_back();
235 WS->setDFSOut(++Counter);
236 }
237 }
238 }
239
240 /// assignInstructionRanges - Find ranges of instructions covered by each
241 /// lexical scope.
242 void LexicalScopes::
assignInstructionRanges(SmallVectorImpl<InsnRange> & MIRanges,DenseMap<const MachineInstr *,LexicalScope * > & MI2ScopeMap)243 assignInstructionRanges(SmallVectorImpl<InsnRange> &MIRanges,
244 DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap)
245 {
246
247 LexicalScope *PrevLexicalScope = NULL;
248 for (SmallVectorImpl<InsnRange>::const_iterator RI = MIRanges.begin(),
249 RE = MIRanges.end(); RI != RE; ++RI) {
250 const InsnRange &R = *RI;
251 LexicalScope *S = MI2ScopeMap.lookup(R.first);
252 assert (S && "Lost LexicalScope for a machine instruction!");
253 if (PrevLexicalScope && !PrevLexicalScope->dominates(S))
254 PrevLexicalScope->closeInsnRange(S);
255 S->openInsnRange(R.first);
256 S->extendInsnRange(R.second);
257 PrevLexicalScope = S;
258 }
259
260 if (PrevLexicalScope)
261 PrevLexicalScope->closeInsnRange();
262 }
263
264 /// getMachineBasicBlocks - Populate given set using machine basic blocks which
265 /// have machine instructions that belong to lexical scope identified by
266 /// DebugLoc.
267 void LexicalScopes::
getMachineBasicBlocks(DebugLoc DL,SmallPtrSet<const MachineBasicBlock *,4> & MBBs)268 getMachineBasicBlocks(DebugLoc DL,
269 SmallPtrSet<const MachineBasicBlock*, 4> &MBBs) {
270 MBBs.clear();
271 LexicalScope *Scope = getOrCreateLexicalScope(DL);
272 if (!Scope)
273 return;
274
275 if (Scope == CurrentFnLexicalScope) {
276 for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
277 I != E; ++I)
278 MBBs.insert(I);
279 return;
280 }
281
282 SmallVector<InsnRange, 4> &InsnRanges = Scope->getRanges();
283 for (SmallVector<InsnRange, 4>::iterator I = InsnRanges.begin(),
284 E = InsnRanges.end(); I != E; ++I) {
285 InsnRange &R = *I;
286 MBBs.insert(R.first->getParent());
287 }
288 }
289
290 /// dominates - Return true if DebugLoc's lexical scope dominates at least one
291 /// machine instruction's lexical scope in a given machine basic block.
dominates(DebugLoc DL,MachineBasicBlock * MBB)292 bool LexicalScopes::dominates(DebugLoc DL, MachineBasicBlock *MBB) {
293 LexicalScope *Scope = getOrCreateLexicalScope(DL);
294 if (!Scope)
295 return false;
296
297 // Current function scope covers all basic blocks in the function.
298 if (Scope == CurrentFnLexicalScope && MBB->getParent() == MF)
299 return true;
300
301 bool Result = false;
302 for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
303 I != E; ++I) {
304 DebugLoc IDL = I->getDebugLoc();
305 if (IDL.isUnknown())
306 continue;
307 if (LexicalScope *IScope = getOrCreateLexicalScope(IDL))
308 if (Scope->dominates(IScope))
309 return true;
310 }
311 return Result;
312 }
313
anchor()314 void LexicalScope::anchor() { }
315
316 /// dump - Print data structures.
dump() const317 void LexicalScope::dump() const {
318 #ifndef NDEBUG
319 raw_ostream &err = dbgs();
320 err.indent(IndentLevel);
321 err << "DFSIn: " << DFSIn << " DFSOut: " << DFSOut << "\n";
322 const MDNode *N = Desc;
323 N->dump();
324 if (AbstractScope)
325 err << "Abstract Scope\n";
326
327 IndentLevel += 2;
328 if (!Children.empty())
329 err << "Children ...\n";
330 for (unsigned i = 0, e = Children.size(); i != e; ++i)
331 if (Children[i] != this)
332 Children[i]->dump();
333
334 IndentLevel -= 2;
335 #endif
336 }
337
338