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LexicalScopes.cpp
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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"
21 #include "llvm/DebugInfo.h"
22 #include "llvm/IR/Function.h"
23 #include "llvm/Support/Debug.h"
26 using namespace llvm;
27 
29  releaseMemory();
30 }
31 
32 /// releaseMemory - release memory.
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.
44  releaseMemory();
45  MF = &Fn;
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::
58 extractLexicalScopes(SmallVectorImpl<InsnRange> &MIRanges,
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.
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.
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.
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.
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.
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
214 void LexicalScopes::constructScopeNest(LexicalScope *Scope) {
215  assert (Scope && "Unable to calculate scope dominance graph!");
217  WorkStack.push_back(Scope);
218  unsigned Counter = 0;
219  while (!WorkStack.empty()) {
220  LexicalScope *WS = WorkStack.back();
221  const SmallVectorImpl<LexicalScope *> &Children = WS->getChildren();
222  bool visitedChildren = false;
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::
243 assignInstructionRanges(SmallVectorImpl<InsnRange> &MIRanges,
245 {
246 
247  LexicalScope *PrevLexicalScope = NULL;
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::
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  SmallVectorImpl<InsnRange> &InsnRanges = Scope->getRanges();
283  for (SmallVectorImpl<InsnRange>::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.
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 
314 void LexicalScope::anchor() { }
315 
316 /// dump - Print data structures.
317 void LexicalScope::dump(unsigned Indent) const {
318 #ifndef NDEBUG
319  raw_ostream &err = dbgs();
320  err.indent(Indent);
321  err << "DFSIn: " << DFSIn << " DFSOut: " << DFSOut << "\n";
322  const MDNode *N = Desc;
323  err.indent(Indent);
324  N->dump();
325  if (AbstractScope)
326  err << std::string(Indent, ' ') << "Abstract Scope\n";
327 
328  if (!Children.empty())
329  err << std::string(Indent + 2, ' ') << "Children ...\n";
330  for (unsigned i = 0, e = Children.size(); i != e; ++i)
331  if (Children[i] != this)
332  Children[i]->dump(Indent + 2);
333 #endif
334 }
335 
void DeleteContainerSeconds(Container &C)
Definition: STLExtras.h:324
void push_back(const T &Elt)
Definition: SmallVector.h:236
const MachineFunction * getParent() const
void openInsnRange(const MachineInstr *MI)
openInsnRange - This scope covers instruction range starting from MI.
void dump(unsigned Indent=0) const
dump - print lexical scope.
void extendInsnRange(const MachineInstr *MI)
LLVMContext & getContext() const
Definition: Function.cpp:167
raw_ostream & indent(unsigned NumSpaces)
indent - Insert 'NumSpaces' spaces.
bool insert(PtrType Ptr)
Definition: SmallPtrSet.h:253
SmallVectorImpl< InsnRange > & getRanges()
void getScopeAndInlinedAt(MDNode *&Scope, MDNode *&IA, const LLVMContext &Ctx) const
getScopeAndInlinedAt - Return both the Scope and the InlinedAt values.
Definition: DebugLoc.cpp:49
MDNode - a tuple of other values.
Definition: Metadata.h:69
const Function * getFunction() const
bool isUnknown() const
isUnknown - Return true if this is an unknown location.
Definition: DebugLoc.h:70
void dump() const
dump - Support for debugging, callable in GDB: V->dump()
Definition: AsmWriter.cpp:2212
SmallVectorImpl< LexicalScope * > & getChildren()
void setDFSOut(unsigned O)
DISubprogram - This is a wrapper for a subprogram (e.g. a function).
Definition: DebugInfo.h:429
bool LLVM_ATTRIBUTE_UNUSED_RESULT empty() const
Definition: SmallVector.h:56
virtual void initialize(const MachineFunction &)
initialize - Scan machine function and constuct lexical scope nest.
bool dominates(DebugLoc DL, MachineBasicBlock *MBB)
LexicalScope * findLexicalScope(DebugLoc DL)
DILexicalBlock - This is a wrapper for a lexical block.
Definition: DebugInfo.h:498
bool isDebugValue() const
Definition: MachineInstr.h:639
static DebugLoc getFromDILexicalBlock(MDNode *N)
getFromDILexicalBlock - Translate the DILexicalBlock into a DebugLoc.
Definition: DebugLoc.cpp:126
bundle_iterator< MachineInstr, instr_iterator > iterator
void closeInsnRange(LexicalScope *NewScope=NULL)
bool dominates(const LexicalScope *S) const
dominates - Return true if current scope dominates given lexical scope.
DILexicalBlock getScope() const
Definition: DebugInfo.h:519
unsigned getDFSOut() const
void setDFSIn(unsigned I)
bool isLexicalBlockFile() const
Definition: DebugInfo.cpp:291
raw_ostream & dbgs()
dbgs - Return a circular-buffered debug stream.
Definition: Debug.cpp:101
bundle_iterator< const MachineInstr, const_instr_iterator > const_iterator
#define I(x, y, z)
Definition: MD5.cpp:54
#define N
static DebugLoc getFromDILocation(MDNode *N)
getFromDILocation - Translate the DILocation quad into a DebugLoc.
Definition: DebugLoc.cpp:117
std::pair< const MachineInstr *, const MachineInstr * > InsnRange
Definition: LexicalScopes.h:33
virtual void releaseMemory()
releaseMemory - release memory.
bool isLexicalBlock() const
isLexicalBlock - Return true if the specified tag is DW_TAG_lexical_block.
Definition: DebugInfo.cpp:297
void getMachineBasicBlocks(DebugLoc DL, SmallPtrSet< const MachineBasicBlock *, 4 > &MBBs)
DebugLoc getDebugLoc() const
Definition: MachineInstr.h:244