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 #define DEBUG_TYPE "lexicalscopes"
  18 #include "llvm/CodeGen/LexicalScopes.h"
  19 #include "llvm/CodeGen/MachineFunction.h"
  20 #include "llvm/CodeGen/MachineInstr.h"
  21 #include "llvm/DebugInfo.h"
  22 #include "llvm/IR/Function.h"
  23 #include "llvm/Support/Debug.h"
  24 #include "llvm/Support/ErrorHandling.h"
  25 #include "llvm/Support/FormattedStream.h"
  26 using namespace llvm;
  27
  28 LexicalScopes::~LexicalScopes() { releaseMemory(); }
  29
  30 /// releaseMemory - release memory.
  31 void LexicalScopes::releaseMemory() {
  32   MF = NULL;
  33   CurrentFnLexicalScope = NULL;
  34   DeleteContainerSeconds(LexicalScopeMap);
  35   DeleteContainerSeconds(AbstractScopeMap);
  36   InlinedLexicalScopeMap.clear();
  37   AbstractScopesList.clear();
  38 }
  39
  40 /// initialize - Scan machine function and constuct lexical scope nest.
  41 void LexicalScopes::initialize(const MachineFunction &Fn) {
  42   releaseMemory();
  43   MF = &Fn;
  44   SmallVector<InsnRange, 4> MIRanges;
  45   DenseMap<const MachineInstr *, LexicalScope *> MI2ScopeMap;
  46   extractLexicalScopes(MIRanges, MI2ScopeMap);
  47   if (CurrentFnLexicalScope) {
  48     constructScopeNest(CurrentFnLexicalScope);
  49     assignInstructionRanges(MIRanges, MI2ScopeMap);
  50   }
  51 }
  52
  53 /// extractLexicalScopes - Extract instruction ranges for each lexical scopes
  54 /// for the given machine function.
  55 void LexicalScopes::extractLexicalScopes(
  56     SmallVectorImpl<InsnRange> &MIRanges,
  57     DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
  58
  59   // Scan each instruction and create scopes. First build working set of scopes.
  60   for (MachineFunction::const_iterator I = MF->begin(), E = MF->end(); I != E;
  61        ++I) {
  62     const MachineInstr *RangeBeginMI = NULL;
  63     const MachineInstr *PrevMI = NULL;
  64     DebugLoc PrevDL;
  65     for (MachineBasicBlock::const_iterator II = I->begin(), IE = I->end();
  66          II != IE; ++II) {
  67       const MachineInstr *MInsn = II;
  68
  69       // Check if instruction has valid location information.
  70       const DebugLoc MIDL = MInsn->getDebugLoc();
  71       if (MIDL.isUnknown()) {
  72         PrevMI = MInsn;
  73         continue;
  74       }
  75
  76       // If scope has not changed then skip this instruction.
  77       if (MIDL == PrevDL) {
  78         PrevMI = MInsn;
  79         continue;
  80       }
  81
  82       // Ignore DBG_VALUE. It does not contribute to any instruction in output.
  83       if (MInsn->isDebugValue())
  84         continue;
  85
  86       if (RangeBeginMI) {
  87         // If we have already seen a beginning of an instruction range and
  88         // current instruction scope does not match scope of first instruction
  89         // in this range then create a new instruction range.
  90         InsnRange R(RangeBeginMI, PrevMI);
  91         MI2ScopeMap[RangeBeginMI] = getOrCreateLexicalScope(PrevDL);
  92         MIRanges.push_back(R);
  93       }
  94
  95       // This is a beginning of a new instruction range.
  96       RangeBeginMI = MInsn;
  97
  98       // Reset previous markers.
  99       PrevMI = MInsn;
 100       PrevDL = MIDL;
 101     }
 102
 103     // Create last instruction range.
 104     if (RangeBeginMI && PrevMI && !PrevDL.isUnknown()) {
 105       InsnRange R(RangeBeginMI, PrevMI);
 106       MIRanges.push_back(R);
 107       MI2ScopeMap[RangeBeginMI] = getOrCreateLexicalScope(PrevDL);
 108     }
 109   }
 110 }
 111
 112 /// findLexicalScope - Find lexical scope, either regular or inlined, for the
 113 /// given DebugLoc. Return NULL if not found.
 114 LexicalScope *LexicalScopes::findLexicalScope(DebugLoc DL) {
 115   MDNode *Scope = NULL;
 116   MDNode *IA = NULL;
 117   DL.getScopeAndInlinedAt(Scope, IA, MF->getFunction()->getContext());
 118   if (!Scope)
 119     return NULL;
 120
 121   // The scope that we were created with could have an extra file - which
 122   // isn't what we care about in this case.
 123   DIDescriptor D = DIDescriptor(Scope);
 124   if (D.isLexicalBlockFile())
 125     Scope = DILexicalBlockFile(Scope).getScope();
 126
 127   if (IA)
 128     return InlinedLexicalScopeMap.lookup(DebugLoc::getFromDILocation(IA));
 129   return LexicalScopeMap.lookup(Scope);
 130 }
 131
 132 /// getOrCreateLexicalScope - Find lexical scope for the given DebugLoc. If
 133 /// not available then create new lexical scope.
 134 LexicalScope *LexicalScopes::getOrCreateLexicalScope(DebugLoc DL) {
 135   MDNode *Scope = NULL;
 136   MDNode *InlinedAt = NULL;
 137   DL.getScopeAndInlinedAt(Scope, InlinedAt, MF->getFunction()->getContext());
 138
 139   if (InlinedAt) {
 140     // Create an abstract scope for inlined function.
 141     getOrCreateAbstractScope(Scope);
 142     // Create an inlined scope for inlined function.
 143     return getOrCreateInlinedScope(Scope, InlinedAt);
 144   }
 145
 146   return getOrCreateRegularScope(Scope);
 147 }
 148
 149 /// getOrCreateRegularScope - Find or create a regular lexical scope.
 150 LexicalScope *LexicalScopes::getOrCreateRegularScope(MDNode *Scope) {
 151   DIDescriptor D = DIDescriptor(Scope);
 152   if (D.isLexicalBlockFile()) {
 153     Scope = DILexicalBlockFile(Scope).getScope();
 154     D = DIDescriptor(Scope);
 155   }
 156
 157   LexicalScope *WScope = LexicalScopeMap.lookup(Scope);
 158   if (WScope)
 159     return WScope;
 160
 161   LexicalScope *Parent = NULL;
 162   if (D.isLexicalBlock())
 163     Parent = getOrCreateLexicalScope(DebugLoc::getFromDILexicalBlock(Scope));
 164   WScope = new LexicalScope(Parent, DIDescriptor(Scope), NULL, false);
 165   LexicalScopeMap.insert(std::make_pair(Scope, WScope));
 166   if (!Parent && DIDescriptor(Scope).isSubprogram() &&
 167       DISubprogram(Scope).describes(MF->getFunction()))
 168     CurrentFnLexicalScope = WScope;
 169
 170   return WScope;
 171 }
 172
 173 /// getOrCreateInlinedScope - Find or create an inlined lexical scope.
 174 LexicalScope *LexicalScopes::getOrCreateInlinedScope(MDNode *Scope,
 175                                                      MDNode *InlinedAt) {
 176   LexicalScope *InlinedScope = LexicalScopeMap.lookup(InlinedAt);
 177   if (InlinedScope)
 178     return InlinedScope;
 179
 180   DebugLoc InlinedLoc = DebugLoc::getFromDILocation(InlinedAt);
 181   InlinedScope = new LexicalScope(getOrCreateLexicalScope(InlinedLoc),
 182                                   DIDescriptor(Scope), InlinedAt, false);
 183   InlinedLexicalScopeMap[InlinedLoc] = InlinedScope;
 184   LexicalScopeMap[InlinedAt] = InlinedScope;
 185   return InlinedScope;
 186 }
 187
 188 /// getOrCreateAbstractScope - Find or create an abstract lexical scope.
 189 LexicalScope *LexicalScopes::getOrCreateAbstractScope(const MDNode *N) {
 190   assert(N && "Invalid Scope encoding!");
 191
 192   DIDescriptor Scope(N);
 193   if (Scope.isLexicalBlockFile())
 194     Scope = DILexicalBlockFile(Scope).getScope();
 195   LexicalScope *AScope = AbstractScopeMap.lookup(N);
 196   if (AScope)
 197     return AScope;
 198
 199   LexicalScope *Parent = NULL;
 200   if (Scope.isLexicalBlock()) {
 201     DILexicalBlock DB(N);
 202     DIDescriptor ParentDesc = DB.getContext();
 203     Parent = getOrCreateAbstractScope(ParentDesc);
 204   }
 205   AScope = new LexicalScope(Parent, DIDescriptor(N), NULL, true);
 206   AbstractScopeMap[N] = AScope;
 207   if (DIDescriptor(N).isSubprogram())
 208     AbstractScopesList.push_back(AScope);
 209   return AScope;
 210 }
 211
 212 /// constructScopeNest
 213 void LexicalScopes::constructScopeNest(LexicalScope *Scope) {
 214   assert(Scope && "Unable to calculate scope dominance graph!");
 215   SmallVector<LexicalScope *, 4> WorkStack;
 216   WorkStack.push_back(Scope);
 217   unsigned Counter = 0;
 218   while (!WorkStack.empty()) {
 219     LexicalScope *WS = WorkStack.back();
 220     const SmallVectorImpl<LexicalScope *> &Children = WS->getChildren();
 221     bool visitedChildren = false;
 222     for (SmallVectorImpl<LexicalScope *>::const_iterator SI = Children.begin(),
 223                                                          SE = Children.end();
 224          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(
 243     SmallVectorImpl<InsnRange> &MIRanges,
 244     DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
 245
 246   LexicalScope *PrevLexicalScope = NULL;
 247   for (SmallVectorImpl<InsnRange>::const_iterator RI = MIRanges.begin(),
 248                                                   RE = MIRanges.end();
 249        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(
 268     DebugLoc DL, SmallPtrSet<const MachineBasicBlock *, 4> &MBBs) {
 269   MBBs.clear();
 270   LexicalScope *Scope = getOrCreateLexicalScope(DL);
 271   if (!Scope)
 272     return;
 273
 274   if (Scope == CurrentFnLexicalScope) {
 275     for (MachineFunction::const_iterator I = MF->begin(), E = MF->end(); I != E;
 276          ++I)
 277       MBBs.insert(I);
 278     return;
 279   }
 280
 281   SmallVectorImpl<InsnRange> &InsnRanges = Scope->getRanges();
 282   for (SmallVectorImpl<InsnRange>::iterator I = InsnRanges.begin(),
 283                                             E = InsnRanges.end();
 284        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.
 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(); I != E;
 303        ++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 }