lib/Bitcode/Writer/ValueEnumerator.cpp

   1 //===-- ValueEnumerator.cpp - Number values and types for bitcode writer --===//
   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 the ValueEnumerator class.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "ValueEnumerator.h"
  15 #include "llvm/ADT/SmallPtrSet.h"
  16 #include "llvm/ADT/STLExtras.h"
  17 #include "llvm/Constants.h"
  18 #include "llvm/DerivedTypes.h"
  19 #include "llvm/Module.h"
  20 #include "llvm/ValueSymbolTable.h"
  21 #include "llvm/Instructions.h"
  22 #include <algorithm>
  23 using namespace llvm;
  24
  25 static bool isIntegerValue(const std::pair<const Value*, unsigned> &V) {
  26   return V.first->getType()->isIntegerTy();
  27 }
  28
  29 /// ValueEnumerator - Enumerate module-level information.
  30 ValueEnumerator::ValueEnumerator(const Module *M) {
  31   // Enumerate the global variables.
  32   for (Module::const_global_iterator I = M->global_begin(),
  33          E = M->global_end(); I != E; ++I)
  34     EnumerateValue(I);
  35
  36   // Enumerate the functions.
  37   for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I) {
  38     EnumerateValue(I);
  39     EnumerateAttributes(cast<Function>(I)->getAttributes());
  40   }
  41
  42   // Enumerate the aliases.
  43   for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
  44        I != E; ++I)
  45     EnumerateValue(I);
  46
  47   // Remember what is the cutoff between globalvalue's and other constants.
  48   unsigned FirstConstant = Values.size();
  49
  50   // Enumerate the global variable initializers.
  51   for (Module::const_global_iterator I = M->global_begin(),
  52          E = M->global_end(); I != E; ++I)
  53     if (I->hasInitializer())
  54       EnumerateValue(I->getInitializer());
  55
  56   // Enumerate the aliasees.
  57   for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
  58        I != E; ++I)
  59     EnumerateValue(I->getAliasee());
  60
  61   // Insert constants and metadata that are named at module level into the slot
  62   // pool so that the module symbol table can refer to them...
  63   EnumerateValueSymbolTable(M->getValueSymbolTable());
  64   EnumerateNamedMetadata(M);
  65
  66   SmallVector<std::pair<unsigned, MDNode*>, 8> MDs;
  67
  68   // Enumerate types used by function bodies and argument lists.
  69   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
  70
  71     for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
  72          I != E; ++I)
  73       EnumerateType(I->getType());
  74
  75     for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
  76       for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E;++I){
  77         for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
  78              OI != E; ++OI) {
  79           if (MDNode *MD = dyn_cast<MDNode>(*OI))
  80             if (MD->isFunctionLocal() && MD->getFunction())
  81               // These will get enumerated during function-incorporation.
  82               continue;
  83           EnumerateOperandType(*OI);
  84         }
  85         EnumerateType(I->getType());
  86         if (const CallInst *CI = dyn_cast<CallInst>(I))
  87           EnumerateAttributes(CI->getAttributes());
  88         else if (const InvokeInst *II = dyn_cast<InvokeInst>(I))
  89           EnumerateAttributes(II->getAttributes());
  90
  91         // Enumerate metadata attached with this instruction.
  92         MDs.clear();
  93         I->getAllMetadataOtherThanDebugLoc(MDs);
  94         for (unsigned i = 0, e = MDs.size(); i != e; ++i)
  95           EnumerateMetadata(MDs[i].second);
  96
  97         if (!I->getDebugLoc().isUnknown()) {
  98           MDNode *Scope, *IA;
  99           I->getDebugLoc().getScopeAndInlinedAt(Scope, IA, I->getContext());
 100           if (Scope) EnumerateMetadata(Scope);
 101           if (IA) EnumerateMetadata(IA);
 102         }
 103       }
 104   }
 105
 106   // Optimize constant ordering.
 107   OptimizeConstants(FirstConstant, Values.size());
 108 }
 109
 110
 111 unsigned ValueEnumerator::getInstructionID(const Instruction *Inst) const {
 112   InstructionMapType::const_iterator I = InstructionMap.find(Inst);
 113   assert(I != InstructionMap.end() && "Instruction is not mapped!");
 114   return I->second;
 115 }
 116
 117 void ValueEnumerator::setInstructionID(const Instruction *I) {
 118   InstructionMap[I] = InstructionCount++;
 119 }
 120
 121 unsigned ValueEnumerator::getValueID(const Value *V) const {
 122   if (isa<MDNode>(V) || isa<MDString>(V)) {
 123     ValueMapType::const_iterator I = MDValueMap.find(V);
 124     assert(I != MDValueMap.end() && "Value not in slotcalculator!");
 125     return I->second-1;
 126   }
 127
 128   ValueMapType::const_iterator I = ValueMap.find(V);
 129   assert(I != ValueMap.end() && "Value not in slotcalculator!");
 130   return I->second-1;
 131 }
 132
 133 // Optimize constant ordering.
 134 namespace {
 135   struct CstSortPredicate {
 136     ValueEnumerator &VE;
 137     explicit CstSortPredicate(ValueEnumerator &ve) : VE(ve) {}
 138     bool operator()(const std::pair<const Value*, unsigned> &LHS,
 139                     const std::pair<const Value*, unsigned> &RHS) {
 140       // Sort by plane.
 141       if (LHS.first->getType() != RHS.first->getType())
 142         return VE.getTypeID(LHS.first->getType()) <
 143                VE.getTypeID(RHS.first->getType());
 144       // Then by frequency.
 145       return LHS.second > RHS.second;
 146     }
 147   };
 148 }
 149
 150 /// OptimizeConstants - Reorder constant pool for denser encoding.
 151 void ValueEnumerator::OptimizeConstants(unsigned CstStart, unsigned CstEnd) {
 152   if (CstStart == CstEnd || CstStart+1 == CstEnd) return;
 153
 154   CstSortPredicate P(*this);
 155   std::stable_sort(Values.begin()+CstStart, Values.begin()+CstEnd, P);
 156
 157   // Ensure that integer constants are at the start of the constant pool.  This
 158   // is important so that GEP structure indices come before gep constant exprs.
 159   std::partition(Values.begin()+CstStart, Values.begin()+CstEnd,
 160                  isIntegerValue);
 161
 162   // Rebuild the modified portion of ValueMap.
 163   for (; CstStart != CstEnd; ++CstStart)
 164     ValueMap[Values[CstStart].first] = CstStart+1;
 165 }
 166
 167
 168 /// EnumerateValueSymbolTable - Insert all of the values in the specified symbol
 169 /// table into the values table.
 170 void ValueEnumerator::EnumerateValueSymbolTable(const ValueSymbolTable &VST) {
 171   for (ValueSymbolTable::const_iterator VI = VST.begin(), VE = VST.end();
 172        VI != VE; ++VI)
 173     EnumerateValue(VI->getValue());
 174 }
 175
 176 /// EnumerateNamedMetadata - Insert all of the values referenced by
 177 /// named metadata in the specified module.
 178 void ValueEnumerator::EnumerateNamedMetadata(const Module *M) {
 179   for (Module::const_named_metadata_iterator I = M->named_metadata_begin(),
 180        E = M->named_metadata_end(); I != E; ++I)
 181     EnumerateNamedMDNode(I);
 182 }
 183
 184 void ValueEnumerator::EnumerateNamedMDNode(const NamedMDNode *MD) {
 185   for (unsigned i = 0, e = MD->getNumOperands(); i != e; ++i)
 186     EnumerateMetadata(MD->getOperand(i));
 187 }
 188
 189 /// EnumerateMDNodeOperands - Enumerate all non-function-local values
 190 /// and types referenced by the given MDNode.
 191 void ValueEnumerator::EnumerateMDNodeOperands(const MDNode *N) {
 192   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
 193     if (Value *V = N->getOperand(i)) {
 194       if (isa<MDNode>(V) || isa<MDString>(V))
 195         EnumerateMetadata(V);
 196       else if (!isa<Instruction>(V) && !isa<Argument>(V))
 197         EnumerateValue(V);
 198     } else
 199       EnumerateType(Type::getVoidTy(N->getContext()));
 200   }
 201 }
 202
 203 void ValueEnumerator::EnumerateMetadata(const Value *MD) {
 204   assert((isa<MDNode>(MD) || isa<MDString>(MD)) && "Invalid metadata kind");
 205
 206   // Enumerate the type of this value.
 207   EnumerateType(MD->getType());
 208
 209   const MDNode *N = dyn_cast<MDNode>(MD);
 210
 211   // In the module-level pass, skip function-local nodes themselves, but
 212   // do walk their operands.
 213   if (N && N->isFunctionLocal() && N->getFunction()) {
 214     EnumerateMDNodeOperands(N);
 215     return;
 216   }
 217
 218   // Check to see if it's already in!
 219   unsigned &MDValueID = MDValueMap[MD];
 220   if (MDValueID) {
 221     // Increment use count.
 222     MDValues[MDValueID-1].second++;
 223     return;
 224   }
 225   MDValues.push_back(std::make_pair(MD, 1U));
 226   MDValueID = MDValues.size();
 227
 228   // Enumerate all non-function-local operands.
 229   if (N)
 230     EnumerateMDNodeOperands(N);
 231 }
 232
 233 /// EnumerateFunctionLocalMetadataa - Incorporate function-local metadata
 234 /// information reachable from the given MDNode.
 235 void ValueEnumerator::EnumerateFunctionLocalMetadata(const MDNode *N) {
 236   assert(N->isFunctionLocal() && N->getFunction() &&
 237          "EnumerateFunctionLocalMetadata called on non-function-local mdnode!");
 238
 239   // Enumerate the type of this value.
 240   EnumerateType(N->getType());
 241
 242   // Check to see if it's already in!
 243   unsigned &MDValueID = MDValueMap[N];
 244   if (MDValueID) {
 245     // Increment use count.
 246     MDValues[MDValueID-1].second++;
 247     return;
 248   }
 249   MDValues.push_back(std::make_pair(N, 1U));
 250   MDValueID = MDValues.size();
 251
 252   // To incoroporate function-local information visit all function-local
 253   // MDNodes and all function-local values they reference.
 254   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
 255     if (Value *V = N->getOperand(i)) {
 256       if (MDNode *O = dyn_cast<MDNode>(V)) {
 257         if (O->isFunctionLocal() && O->getFunction())
 258           EnumerateFunctionLocalMetadata(O);
 259       } else if (isa<Instruction>(V) || isa<Argument>(V))
 260         EnumerateValue(V);
 261     }
 262
 263   // Also, collect all function-local MDNodes for easy access.
 264   FunctionLocalMDs.push_back(N);
 265 }
 266
 267 void ValueEnumerator::EnumerateValue(const Value *V) {
 268   assert(!V->getType()->isVoidTy() && "Can't insert void values!");
 269   assert(!isa<MDNode>(V) && !isa<MDString>(V) &&
 270          "EnumerateValue doesn't handle Metadata!");
 271
 272   // Check to see if it's already in!
 273   unsigned &ValueID = ValueMap[V];
 274   if (ValueID) {
 275     // Increment use count.
 276     Values[ValueID-1].second++;
 277     return;
 278   }
 279
 280   // Enumerate the type of this value.
 281   EnumerateType(V->getType());
 282
 283   if (const Constant *C = dyn_cast<Constant>(V)) {
 284     if (isa<GlobalValue>(C)) {
 285       // Initializers for globals are handled explicitly elsewhere.
 286     } else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
 287       // Do not enumerate the initializers for an array of simple characters.
 288       // The initializers just pollute the value table, and we emit the strings
 289       // specially.
 290     } else if (C->getNumOperands()) {
 291       // If a constant has operands, enumerate them.  This makes sure that if a
 292       // constant has uses (for example an array of const ints), that they are
 293       // inserted also.
 294
 295       // We prefer to enumerate them with values before we enumerate the user
 296       // itself.  This makes it more likely that we can avoid forward references
 297       // in the reader.  We know that there can be no cycles in the constants
 298       // graph that don't go through a global variable.
 299       for (User::const_op_iterator I = C->op_begin(), E = C->op_end();
 300            I != E; ++I)
 301         if (!isa<BasicBlock>(*I)) // Don't enumerate BB operand to BlockAddress.
 302           EnumerateValue(*I);
 303
 304       // Finally, add the value.  Doing this could make the ValueID reference be
 305       // dangling, don't reuse it.
 306       Values.push_back(std::make_pair(V, 1U));
 307       ValueMap[V] = Values.size();
 308       return;
 309     }
 310   }
 311
 312   // Add the value.
 313   Values.push_back(std::make_pair(V, 1U));
 314   ValueID = Values.size();
 315 }
 316
 317
 318 void ValueEnumerator::EnumerateType(const Type *Ty) {
 319   unsigned *TypeID = &TypeMap[Ty];
 320
 321   // We've already seen this type.
 322   if (*TypeID)
 323     return;
 324
 325   // If it is a non-anonymous struct, mark the type as being visited so that we
 326   // don't recursively visit it.  This is safe because we allow forward
 327   // references of these in the bitcode reader.
 328   if (const StructType *STy = dyn_cast<StructType>(Ty))
 329     if (!STy->isAnonymous())
 330       *TypeID = ~0U;
 331
 332   // Enumerate all of the subtypes before we enumerate this type.  This ensures
 333   // that the type will be enumerated in an order that can be directly built.
 334   for (Type::subtype_iterator I = Ty->subtype_begin(), E = Ty->subtype_end();
 335        I != E; ++I)
 336     EnumerateType(*I);
 337
 338   // Refresh the TypeID pointer in case the table rehashed.
 339   TypeID = &TypeMap[Ty];
 340
 341   // Check to see if we got the pointer another way.  This can happen when
 342   // enumerating recursive types that hit the base case deeper than they start.
 343   //
 344   // If this is actually a struct that we are treating as forward ref'able,
 345   // then emit the definition now that all of its contents are available.
 346   if (*TypeID && *TypeID != ~0U)
 347     return;
 348
 349   // Add this type now that its contents are all happily enumerated.
 350   Types.push_back(Ty);
 351
 352   *TypeID = Types.size();
 353 }
 354
 355 // Enumerate the types for the specified value.  If the value is a constant,
 356 // walk through it, enumerating the types of the constant.
 357 void ValueEnumerator::EnumerateOperandType(const Value *V) {
 358   EnumerateType(V->getType());
 359
 360   if (const Constant *C = dyn_cast<Constant>(V)) {
 361     // If this constant is already enumerated, ignore it, we know its type must
 362     // be enumerated.
 363     if (ValueMap.count(V)) return;
 364
 365     // This constant may have operands, make sure to enumerate the types in
 366     // them.
 367     for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i) {
 368       const Value *Op = C->getOperand(i);
 369
 370       // Don't enumerate basic blocks here, this happens as operands to
 371       // blockaddress.
 372       if (isa<BasicBlock>(Op)) continue;
 373
 374       EnumerateOperandType(Op);
 375     }
 376
 377     if (const MDNode *N = dyn_cast<MDNode>(V)) {
 378       for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
 379         if (Value *Elem = N->getOperand(i))
 380           EnumerateOperandType(Elem);
 381     }
 382   } else if (isa<MDString>(V) || isa<MDNode>(V))
 383     EnumerateMetadata(V);
 384 }
 385
 386 void ValueEnumerator::EnumerateAttributes(const AttrListPtr &PAL) {
 387   if (PAL.isEmpty()) return;  // null is always 0.
 388   // Do a lookup.
 389   unsigned &Entry = AttributeMap[PAL.getRawPointer()];
 390   if (Entry == 0) {
 391     // Never saw this before, add it.
 392     Attributes.push_back(PAL);
 393     Entry = Attributes.size();
 394   }
 395 }
 396
 397 void ValueEnumerator::incorporateFunction(const Function &F) {
 398   InstructionCount = 0;
 399   NumModuleValues = Values.size();
 400   NumModuleMDValues = MDValues.size();
 401
 402   // Adding function arguments to the value table.
 403   for (Function::const_arg_iterator I = F.arg_begin(), E = F.arg_end();
 404        I != E; ++I)
 405     EnumerateValue(I);
 406
 407   FirstFuncConstantID = Values.size();
 408
 409   // Add all function-level constants to the value table.
 410   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
 411     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E; ++I)
 412       for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
 413            OI != E; ++OI) {
 414         if ((isa<Constant>(*OI) && !isa<GlobalValue>(*OI)) ||
 415             isa<InlineAsm>(*OI))
 416           EnumerateValue(*OI);
 417       }
 418     BasicBlocks.push_back(BB);
 419     ValueMap[BB] = BasicBlocks.size();
 420   }
 421
 422   // Optimize the constant layout.
 423   OptimizeConstants(FirstFuncConstantID, Values.size());
 424
 425   // Add the function's parameter attributes so they are available for use in
 426   // the function's instruction.
 427   EnumerateAttributes(F.getAttributes());
 428
 429   FirstInstID = Values.size();
 430
 431   SmallVector<MDNode *, 8> FnLocalMDVector;
 432   // Add all of the instructions.
 433   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
 434     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E; ++I) {
 435       for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
 436            OI != E; ++OI) {
 437         if (MDNode *MD = dyn_cast<MDNode>(*OI))
 438           if (MD->isFunctionLocal() && MD->getFunction())
 439             // Enumerate metadata after the instructions they might refer to.
 440             FnLocalMDVector.push_back(MD);
 441       }
 442
 443       SmallVector<std::pair<unsigned, MDNode*>, 8> MDs;
 444       I->getAllMetadataOtherThanDebugLoc(MDs);
 445       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
 446         MDNode *N = MDs[i].second;
 447         if (N->isFunctionLocal() && N->getFunction())
 448           FnLocalMDVector.push_back(N);
 449       }
 450
 451       if (!I->getType()->isVoidTy())
 452         EnumerateValue(I);
 453     }
 454   }
 455
 456   // Add all of the function-local metadata.
 457   for (unsigned i = 0, e = FnLocalMDVector.size(); i != e; ++i)
 458     EnumerateFunctionLocalMetadata(FnLocalMDVector[i]);
 459 }
 460
 461 void ValueEnumerator::purgeFunction() {
 462   /// Remove purged values from the ValueMap.
 463   for (unsigned i = NumModuleValues, e = Values.size(); i != e; ++i)
 464     ValueMap.erase(Values[i].first);
 465   for (unsigned i = NumModuleMDValues, e = MDValues.size(); i != e; ++i)
 466     MDValueMap.erase(MDValues[i].first);
 467   for (unsigned i = 0, e = BasicBlocks.size(); i != e; ++i)
 468     ValueMap.erase(BasicBlocks[i]);
 469
 470   Values.resize(NumModuleValues);
 471   MDValues.resize(NumModuleMDValues);
 472   BasicBlocks.clear();
 473   FunctionLocalMDs.clear();
 474 }
 475
 476 static void IncorporateFunctionInfoGlobalBBIDs(const Function *F,
 477                                  DenseMap<const BasicBlock*, unsigned> &IDMap) {
 478   unsigned Counter = 0;
 479   for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
 480     IDMap[BB] = ++Counter;
 481 }
 482
 483 /// getGlobalBasicBlockID - This returns the function-specific ID for the
 484 /// specified basic block.  This is relatively expensive information, so it
 485 /// should only be used by rare constructs such as address-of-label.
 486 unsigned ValueEnumerator::getGlobalBasicBlockID(const BasicBlock *BB) const {
 487   unsigned &Idx = GlobalBasicBlockIDs[BB];
 488   if (Idx != 0)
 489     return Idx-1;
 490
 491   IncorporateFunctionInfoGlobalBBIDs(BB->getParent(), GlobalBasicBlockIDs);
 492   return getGlobalBasicBlockID(BB);
 493 }
 494