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/Function.h"
  20 #include "llvm/Analysis/DebugInfo.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
  28 LexicalScopes::~LexicalScopes() {
  29   releaseMemory();
  30 }
  31
  32 /// releaseMemory - release memory.
  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.
  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::
  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.
 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.
 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
 156   LexicalScope *WScope = LexicalScopeMap.lookup(Scope);
 157   if (WScope)
 158     return WScope;
 159
 160   LexicalScope *Parent = NULL;
 161   if (D.isLexicalBlock())
 162     Parent = getOrCreateLexicalScope(DebugLoc::getFromDILexicalBlock(Scope));
 163   WScope = new LexicalScope(Parent, DIDescriptor(Scope), NULL, false);
 164   LexicalScopeMap.insert(std::make_pair(Scope, WScope));
 165   if (!Parent && DIDescriptor(Scope).isSubprogram()
 166       && DISubprogram(Scope).describes(MF->getFunction()))
 167     CurrentFnLexicalScope = WScope;
 168
 169   return WScope;
 170 }
 171
 172 /// getOrCreateInlinedScope - Find or create an inlined lexical scope.
 173 LexicalScope *LexicalScopes::getOrCreateInlinedScope(MDNode *Scope,
 174                                                      MDNode *InlinedAt) {
 175   LexicalScope *InlinedScope = LexicalScopeMap.lookup(InlinedAt);
 176   if (InlinedScope)
 177     return InlinedScope;
 178
 179   DebugLoc InlinedLoc = DebugLoc::getFromDILocation(InlinedAt);
 180   InlinedScope = new LexicalScope(getOrCreateLexicalScope(InlinedLoc),
 181                                   DIDescriptor(Scope), InlinedAt, false);
 182   InlinedLexicalScopeMap[InlinedLoc] = InlinedScope;
 183   LexicalScopeMap[InlinedAt] = InlinedScope;
 184   return InlinedScope;
 185 }
 186
 187 /// getOrCreateAbstractScope - Find or create an abstract lexical scope.
 188 LexicalScope *LexicalScopes::getOrCreateAbstractScope(const MDNode *N) {
 189   assert(N && "Invalid Scope encoding!");
 190
 191   DIDescriptor Scope(N);
 192   if (Scope.isLexicalBlockFile())
 193     Scope = DILexicalBlockFile(Scope).getScope();
 194   LexicalScope *AScope = AbstractScopeMap.lookup(N);
 195   if (AScope)
 196     return AScope;
 197
 198   LexicalScope *Parent = NULL;
 199   if (Scope.isLexicalBlock()) {
 200     DILexicalBlock DB(N);
 201     DIDescriptor ParentDesc = DB.getContext();
 202     Parent = getOrCreateAbstractScope(ParentDesc);
 203   }
 204   AScope = new LexicalScope(Parent, DIDescriptor(N), NULL, true);
 205   AbstractScopeMap[N] = AScope;
 206   if (DIDescriptor(N).isSubprogram())
 207     AbstractScopesList.push_back(AScope);
 208   return AScope;
 209 }
 210
 211 /// constructScopeNest
 212 void LexicalScopes::constructScopeNest(LexicalScope *Scope) {
 213   assert (Scope && "Unable to calculate scop edominance graph!");
 214   SmallVector<LexicalScope *, 4> WorkStack;
 215   WorkStack.push_back(Scope);
 216   unsigned Counter = 0;
 217   while (!WorkStack.empty()) {
 218     LexicalScope *WS = WorkStack.back();
 219     const SmallVector<LexicalScope *, 4> &Children = WS->getChildren();
 220     bool visitedChildren = false;
 221     for (SmallVector<LexicalScope *, 4>::const_iterator SI = Children.begin(),
 222            SE = Children.end(); SI != SE; ++SI) {
 223       LexicalScope *ChildScope = *SI;
 224       if (!ChildScope->getDFSOut()) {
 225         WorkStack.push_back(ChildScope);
 226         visitedChildren = true;
 227         ChildScope->setDFSIn(++Counter);
 228         break;
 229       }
 230     }
 231     if (!visitedChildren) {
 232       WorkStack.pop_back();
 233       WS->setDFSOut(++Counter);
 234     }
 235   }
 236 }
 237
 238 /// assignInstructionRanges - Find ranges of instructions covered by each
 239 /// lexical scope.
 240 void LexicalScopes::
 241 assignInstructionRanges(SmallVectorImpl<InsnRange> &MIRanges,
 242                     DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap)
 243 {
 244
 245   LexicalScope *PrevLexicalScope = NULL;
 246   for (SmallVectorImpl<InsnRange>::const_iterator RI = MIRanges.begin(),
 247          RE = MIRanges.end(); RI != RE; ++RI) {
 248     const InsnRange &R = *RI;
 249     LexicalScope *S = MI2ScopeMap.lookup(R.first);
 250     assert (S && "Lost LexicalScope for a machine instruction!");
 251     if (PrevLexicalScope && !PrevLexicalScope->dominates(S))
 252       PrevLexicalScope->closeInsnRange(S);
 253     S->openInsnRange(R.first);
 254     S->extendInsnRange(R.second);
 255     PrevLexicalScope = S;
 256   }
 257
 258   if (PrevLexicalScope)
 259     PrevLexicalScope->closeInsnRange();
 260 }
 261
 262 /// getMachineBasicBlocks - Populate given set using machine basic blocks which
 263 /// have machine instructions that belong to lexical scope identified by
 264 /// DebugLoc.
 265 void LexicalScopes::
 266 getMachineBasicBlocks(DebugLoc DL,
 267                       SmallPtrSet<const MachineBasicBlock*, 4> &MBBs) {
 268   MBBs.clear();
 269   LexicalScope *Scope = getOrCreateLexicalScope(DL);
 270   if (!Scope)
 271     return;
 272
 273   if (Scope == CurrentFnLexicalScope) {
 274     for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
 275          I != E; ++I)
 276       MBBs.insert(I);
 277     return;
 278   }
 279
 280   SmallVector<InsnRange, 4> &InsnRanges = Scope->getRanges();
 281   for (SmallVector<InsnRange, 4>::iterator I = InsnRanges.begin(),
 282          E = InsnRanges.end(); I != E; ++I) {
 283     InsnRange &R = *I;
 284     MBBs.insert(R.first->getParent());
 285   }
 286 }
 287
 288 /// dominates - Return true if DebugLoc's lexical scope dominates at least one
 289 /// machine instruction's lexical scope in a given machine basic block.
 290 bool LexicalScopes::dominates(DebugLoc DL, MachineBasicBlock *MBB) {
 291   LexicalScope *Scope = getOrCreateLexicalScope(DL);
 292   if (!Scope)
 293     return false;
 294
 295   // Current function scope covers all basic blocks in the function.
 296   if (Scope == CurrentFnLexicalScope && MBB->getParent() == MF)
 297     return true;
 298
 299   bool Result = false;
 300   for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
 301        I != E; ++I) {
 302     DebugLoc IDL = I->getDebugLoc();
 303     if (IDL.isUnknown())
 304       continue;
 305     if (LexicalScope *IScope = getOrCreateLexicalScope(IDL))
 306       if (Scope->dominates(IScope))
 307         return true;
 308   }
 309   return Result;
 310 }
 311
 312 /// dump - Print data structures.
 313 void LexicalScope::dump() const {
 314 #ifndef NDEBUG
 315   raw_ostream &err = dbgs();
 316   err.indent(IndentLevel);
 317   err << "DFSIn: " << DFSIn << " DFSOut: " << DFSOut << "\n";
 318   const MDNode *N = Desc;
 319   N->dump();
 320   if (AbstractScope)
 321     err << "Abstract Scope\n";
 322
 323   IndentLevel += 2;
 324   if (!Children.empty())
 325     err << "Children ...\n";
 326   for (unsigned i = 0, e = Children.size(); i != e; ++i)
 327     if (Children[i] != this)
 328       Children[i]->dump();
 329
 330   IndentLevel -= 2;
 331 #endif
 332 }
 333