lib/VMCore/SymbolTable.cpp

   1 //===-- SymbolTable.cpp - Implement the SymbolTable class -----------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by the LLVM research group and revised by Reid
   6 // Spencer. It is distributed under the University of Illinois Open Source
   7 // License. See LICENSE.TXT for details.
   8 //
   9 //===----------------------------------------------------------------------===//
  10 //
  11 // This file implements the SymbolTable class for the VMCore library.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "llvm/SymbolTable.h"
  16 #include "llvm/DerivedTypes.h"
  17 #include "llvm/Module.h"
  18 #include "llvm/ADT/StringExtras.h"
  19 #include <algorithm>
  20 #include <iostream>
  21
  22 using namespace llvm;
  23
  24 #define DEBUG_SYMBOL_TABLE 0
  25 #define DEBUG_ABSTYPE 0
  26
  27 SymbolTable::~SymbolTable() {
  28   // Drop all abstract type references in the type plane...
  29   for (type_iterator TI = tmap.begin(), TE = tmap.end(); TI != TE; ++TI) {
  30     if (TI->second->isAbstract())   // If abstract, drop the reference...
  31       cast<DerivedType>(TI->second)->removeAbstractTypeUser(this);
  32   }
  33
  34  // TODO: FIXME: BIG ONE: This doesn't unreference abstract types for the
  35  // planes that could still have entries!
  36
  37 #ifndef NDEBUG   // Only do this in -g mode...
  38   bool LeftoverValues = true;
  39   for (plane_iterator PI = pmap.begin(); PI != pmap.end(); ++PI) {
  40     for (value_iterator VI = PI->second.begin(); VI != PI->second.end(); ++VI)
  41       if (!isa<Constant>(VI->second) ) {
  42         std::cerr << "Value still in symbol table! Type = '"
  43                   << PI->first->getDescription() << "' Name = '"
  44                   << VI->first << "'\n";
  45         LeftoverValues = false;
  46       }
  47   }
  48
  49   assert(LeftoverValues && "Values remain in symbol table!");
  50 #endif
  51 }
  52
  53 // getUniqueName - Given a base name, return a string that is either equal to
  54 // it (or derived from it) that does not already occur in the symbol table for
  55 // the specified type.
  56 //
  57 std::string SymbolTable::getUniqueName(const Type *Ty,
  58                                        const std::string &BaseName) const {
  59   // Find the plane
  60   plane_const_iterator PI = pmap.find(Ty);
  61   if (PI == pmap.end()) return BaseName;
  62
  63   std::string TryName = BaseName;
  64   const ValueMap& vmap = PI->second;
  65   value_const_iterator End = vmap.end();
  66
  67   // See if the name exists
  68   while (vmap.find(TryName) != End)            // Loop until we find a free
  69     TryName = BaseName + utostr(++LastUnique); // name in the symbol table
  70   return TryName;
  71 }
  72
  73
  74 // lookup a value - Returns null on failure...
  75 Value *SymbolTable::lookup(const Type *Ty, const std::string &Name) const {
  76   plane_const_iterator PI = pmap.find(Ty);
  77   if (PI != pmap.end()) {                // We have symbols in that plane.
  78     value_const_iterator VI = PI->second.find(Name);
  79     if (VI != PI->second.end())          // and the name is in our hash table.
  80       return VI->second;
  81   }
  82   return 0;
  83 }
  84
  85
  86 // lookup a type by name - returns null on failure
  87 Type* SymbolTable::lookupType(const std::string& Name) const {
  88   type_const_iterator TI = tmap.find(Name);
  89   if (TI != tmap.end())
  90     return const_cast<Type*>(TI->second);
  91   return 0;
  92 }
  93
  94 /// changeName - Given a value with a non-empty name, remove its existing entry
  95 /// from the symbol table and insert a new one for Name.  This is equivalent to
  96 /// doing "remove(V), V->Name = Name, insert(V)", but is faster, and will not
  97 /// temporarily remove the symbol table plane if V is the last value in the
  98 /// symtab with that name (which could invalidate iterators to that plane).
  99 void SymbolTable::changeName(Value *V, const std::string &name) {
 100   assert(!V->getName().empty() && !name.empty() && V->getName() != name &&
 101          "Illegal use of this method!");
 102
 103   plane_iterator PI = pmap.find(V->getType());
 104   assert(PI != pmap.end() && "Value doesn't have an entry in this table?");
 105   ValueMap &VM = PI->second;
 106
 107   value_iterator VI = VM.find(V->getName());
 108   assert(VI != VM.end() && "Value does have an entry in this table?");
 109
 110   // Remove the old entry.
 111   VM.erase(VI);
 112
 113   // See if we can insert the new name.
 114   VI = VM.lower_bound(name);
 115
 116   // Is there a naming conflict?
 117   if (VI != VM.end() && VI->first == name) {
 118     V->Name = getUniqueName(V->getType(), name);
 119     VM.insert(make_pair(V->Name, V));
 120   } else {
 121     V->Name = name;
 122     VM.insert(VI, make_pair(name, V));
 123   }
 124 }
 125
 126 // Remove a value
 127 void SymbolTable::remove(Value *N) {
 128   assert(N->hasName() && "Value doesn't have name!");
 129
 130   plane_iterator PI = pmap.find(N->getType());
 131   assert(PI != pmap.end() &&
 132          "Trying to remove a value that doesn't have a type plane yet!");
 133   ValueMap &VM = PI->second;
 134   value_iterator Entry = VM.find(N->getName());
 135   assert(Entry != VM.end() && "Invalid entry to remove!");
 136
 137 #if DEBUG_SYMBOL_TABLE
 138   dump();
 139   std::cerr << " Removing Value: " << Entry->second->getName() << "\n";
 140 #endif
 141
 142   // Remove the value from the plane...
 143   VM.erase(Entry);
 144
 145   // If the plane is empty, remove it now!
 146   if (VM.empty()) {
 147     // If the plane represented an abstract type that we were interested in,
 148     // unlink ourselves from this plane.
 149     //
 150     if (N->getType()->isAbstract()) {
 151 #if DEBUG_ABSTYPE
 152       std::cerr << "Plane Empty: Removing type: "
 153                 << N->getType()->getDescription() << "\n";
 154 #endif
 155       cast<DerivedType>(N->getType())->removeAbstractTypeUser(this);
 156     }
 157
 158     pmap.erase(PI);
 159   }
 160 }
 161
 162 // remove - Remove a type from the symbol table...
 163 Type* SymbolTable::remove(type_iterator Entry) {
 164   assert(Entry != tmap.end() && "Invalid entry to remove!");
 165
 166   const Type* Result = Entry->second;
 167
 168 #if DEBUG_SYMBOL_TABLE
 169   dump();
 170   std::cerr << " Removing Value: " << Result->getName() << "\n";
 171 #endif
 172
 173   tmap.erase(Entry);
 174
 175   // If we are removing an abstract type, remove the symbol table from it's use
 176   // list...
 177   if (Result->isAbstract()) {
 178 #if DEBUG_ABSTYPE
 179     std::cerr << "Removing abstract type from symtab" << Result->getDescription()<<"\n";
 180 #endif
 181     cast<DerivedType>(Result)->removeAbstractTypeUser(this);
 182   }
 183
 184   return const_cast<Type*>(Result);
 185 }
 186
 187
 188 // insertEntry - Insert a value into the symbol table with the specified name.
 189 void SymbolTable::insertEntry(const std::string &Name, const Type *VTy,
 190                               Value *V) {
 191   plane_iterator PI = pmap.find(VTy);   // Plane iterator
 192   value_iterator VI;                    // Actual value iterator
 193   ValueMap *VM;                         // The plane we care about.
 194
 195 #if DEBUG_SYMBOL_TABLE
 196   dump();
 197   std::cerr << " Inserting definition: " << Name << ": "
 198             << VTy->getDescription() << "\n";
 199 #endif
 200
 201   if (PI == pmap.end()) {      // Not in collection yet... insert dummy entry
 202     // Insert a new empty element.  I points to the new elements.
 203     VM = &pmap.insert(make_pair(VTy, ValueMap())).first->second;
 204     VI = VM->end();
 205
 206     // Check to see if the type is abstract.  If so, it might be refined in the
 207     // future, which would cause the plane of the old type to get merged into
 208     // a new type plane.
 209     //
 210     if (VTy->isAbstract()) {
 211       cast<DerivedType>(VTy)->addAbstractTypeUser(this);
 212 #if DEBUG_ABSTYPE
 213       std::cerr << "Added abstract type value: " << VTy->getDescription()
 214                 << "\n";
 215 #endif
 216     }
 217
 218   } else {
 219     // Check to see if there is a naming conflict.  If so, rename this value!
 220     VM = &PI->second;
 221     VI = VM->lower_bound(Name);
 222     if (VI != VM->end() && VI->first == Name) {
 223       V->Name = getUniqueName(VTy, Name);
 224       VM->insert(make_pair(V->Name, V));
 225       return;
 226     }
 227   }
 228
 229   VM->insert(VI, make_pair(Name, V));
 230 }
 231
 232
 233 // insertEntry - Insert a value into the symbol table with the specified
 234 // name...
 235 //
 236 void SymbolTable::insert(const std::string& Name, const Type* T) {
 237   assert(T && "Can't insert null type into symbol table!");
 238
 239   // Check to see if there is a naming conflict.  If so, rename this type!
 240   std::string UniqueName = Name;
 241   if (lookupType(Name))
 242     UniqueName = getUniqueName(T, Name);
 243
 244 #if DEBUG_SYMBOL_TABLE
 245   dump();
 246   std::cerr << " Inserting type: " << UniqueName << ": "
 247             << T->getDescription() << "\n";
 248 #endif
 249
 250   // Insert the tmap entry
 251   tmap.insert(make_pair(UniqueName, T));
 252
 253   // If we are adding an abstract type, add the symbol table to it's use list.
 254   if (T->isAbstract()) {
 255     cast<DerivedType>(T)->addAbstractTypeUser(this);
 256 #if DEBUG_ABSTYPE
 257     std::cerr << "Added abstract type to ST: " << T->getDescription() << "\n";
 258 #endif
 259   }
 260 }
 261
 262 // Strip the symbol table of its names.
 263 bool SymbolTable::strip() {
 264   bool RemovedSymbol = false;
 265   for (plane_iterator I = pmap.begin(); I != pmap.end();) {
 266     // Removing items from the plane can cause the plane itself to get deleted.
 267     // If this happens, make sure we incremented our plane iterator already!
 268     ValueMap &Plane = (I++)->second;
 269     value_iterator B = Plane.begin(), Bend = Plane.end();
 270     while (B != Bend) {   // Found nonempty type plane!
 271       Value *V = B->second;
 272       if (!isa<GlobalValue>(V) || cast<GlobalValue>(V)->hasInternalLinkage()) {
 273         // Set name to "", removing from symbol table!
 274         V->setName("");
 275         RemovedSymbol = true;
 276       }
 277       ++B;
 278     }
 279   }
 280
 281   for (type_iterator TI = tmap.begin(); TI != tmap.end(); ) {
 282     remove(TI++);
 283     RemovedSymbol = true;
 284   }
 285
 286   return RemovedSymbol;
 287 }
 288
 289
 290 // This function is called when one of the types in the type plane are refined
 291 void SymbolTable::refineAbstractType(const DerivedType *OldType,
 292                                      const Type *NewType) {
 293
 294   // Search to see if we have any values of the type Oldtype.  If so, we need to
 295   // move them into the newtype plane...
 296   plane_iterator PI = pmap.find(OldType);
 297   if (PI != pmap.end()) {
 298     // Get a handle to the new type plane...
 299     plane_iterator NewTypeIt = pmap.find(NewType);
 300     if (NewTypeIt == pmap.end()) {      // If no plane exists, add one
 301       NewTypeIt = pmap.insert(make_pair(NewType, ValueMap())).first;
 302
 303       if (NewType->isAbstract()) {
 304         cast<DerivedType>(NewType)->addAbstractTypeUser(this);
 305 #if DEBUG_ABSTYPE
 306         std::cerr << "[Added] refined to abstype: " << NewType->getDescription()
 307                   << "\n";
 308 #endif
 309       }
 310     }
 311
 312     ValueMap &NewPlane = NewTypeIt->second;
 313     ValueMap &OldPlane = PI->second;
 314     while (!OldPlane.empty()) {
 315       std::pair<const std::string, Value*> V = *OldPlane.begin();
 316
 317       // Check to see if there is already a value in the symbol table that this
 318       // would collide with.
 319       value_iterator VI = NewPlane.find(V.first);
 320       if (VI != NewPlane.end() && VI->second == V.second) {
 321         // No action
 322
 323       } else if (VI != NewPlane.end()) {
 324         // The only thing we are allowing for now is two external global values
 325         // folded into one.
 326         //
 327         GlobalValue *ExistGV = dyn_cast<GlobalValue>(VI->second);
 328         GlobalValue *NewGV = dyn_cast<GlobalValue>(V.second);
 329
 330         if (ExistGV && NewGV) {
 331           assert((ExistGV->isExternal() || NewGV->isExternal()) &&
 332                  "Two planes folded together with overlapping value names!");
 333
 334           // Make sure that ExistGV is the one we want to keep!
 335           if (!NewGV->isExternal())
 336             std::swap(NewGV, ExistGV);
 337
 338           // Ok we have two external global values.  Make all uses of the new
 339           // one use the old one...
 340           NewGV->uncheckedReplaceAllUsesWith(ExistGV);
 341
 342           // Update NewGV's name, we're about the remove it from the symbol
 343           // table.
 344           NewGV->Name = "";
 345
 346           // Now we can remove this global from the module entirely...
 347           Module *M = NewGV->getParent();
 348           if (Function *F = dyn_cast<Function>(NewGV))
 349             M->getFunctionList().remove(F);
 350           else
 351             M->getGlobalList().remove(cast<GlobalVariable>(NewGV));
 352           delete NewGV;
 353         } else {
 354           // If they are not global values, they must be just random values who
 355           // happen to conflict now that types have been resolved.  If this is
 356           // the case, reinsert the value into the new plane, allowing it to get
 357           // renamed.
 358           assert(V.second->getType() == NewType &&"Type resolution is broken!");
 359           insert(V.second);
 360         }
 361       } else {
 362         insertEntry(V.first, NewType, V.second);
 363       }
 364       // Remove the item from the old type plane
 365       OldPlane.erase(OldPlane.begin());
 366     }
 367
 368     // Ok, now we are not referencing the type anymore... take me off your user
 369     // list please!
 370 #if DEBUG_ABSTYPE
 371     std::cerr << "Removing type " << OldType->getDescription() << "\n";
 372 #endif
 373     OldType->removeAbstractTypeUser(this);
 374
 375     // Remove the plane that is no longer used
 376     pmap.erase(PI);
 377   }
 378
 379   // Loop over all of the types in the symbol table, replacing any references
 380   // to OldType with references to NewType.  Note that there may be multiple
 381   // occurrences, and although we only need to remove one at a time, it's
 382   // faster to remove them all in one pass.
 383   //
 384   for (type_iterator I = type_begin(), E = type_end(); I != E; ++I) {
 385     if (I->second == (Type*)OldType) {  // FIXME when Types aren't const.
 386 #if DEBUG_ABSTYPE
 387       std::cerr << "Removing type " << OldType->getDescription() << "\n";
 388 #endif
 389       OldType->removeAbstractTypeUser(this);
 390
 391       I->second = (Type*)NewType;  // TODO FIXME when types aren't const
 392       if (NewType->isAbstract()) {
 393 #if DEBUG_ABSTYPE
 394         std::cerr << "Added type " << NewType->getDescription() << "\n";
 395 #endif
 396         cast<DerivedType>(NewType)->addAbstractTypeUser(this);
 397       }
 398     }
 399   }
 400 }
 401
 402
 403 // Handle situation where type becomes Concreate from Abstract
 404 void SymbolTable::typeBecameConcrete(const DerivedType *AbsTy) {
 405   plane_iterator PI = pmap.find(AbsTy);
 406
 407   // If there are any values in the symbol table of this type, then the type
 408   // plane is a use of the abstract type which must be dropped.
 409   if (PI != pmap.end())
 410     AbsTy->removeAbstractTypeUser(this);
 411
 412   // Loop over all of the types in the symbol table, dropping any abstract
 413   // type user entries for AbsTy which occur because there are names for the
 414   // type.
 415   for (type_iterator TI = type_begin(), TE = type_end(); TI != TE; ++TI)
 416     if (TI->second == (Type*)AbsTy)   // FIXME when Types aren't const.
 417       AbsTy->removeAbstractTypeUser(this);
 418 }
 419
 420 static void DumpVal(const std::pair<const std::string, Value *> &V) {
 421   std::cerr << "  '" << V.first << "' = ";
 422   V.second->dump();
 423   std::cerr << "\n";
 424 }
 425
 426 static void DumpPlane(const std::pair<const Type *,
 427                                       std::map<const std::string, Value *> >&P){
 428   P.first->dump();
 429   std::cerr << "\n";
 430   for_each(P.second.begin(), P.second.end(), DumpVal);
 431 }
 432
 433 static void DumpTypes(const std::pair<const std::string, const Type*>& T ) {
 434   std::cerr << "  '" << T.first << "' = ";
 435   T.second->dump();
 436   std::cerr << "\n";
 437 }
 438
 439 void SymbolTable::dump() const {
 440   std::cerr << "Symbol table dump:\n  Plane:";
 441   for_each(pmap.begin(), pmap.end(), DumpPlane);
 442   std::cerr << "  Types: ";
 443   for_each(tmap.begin(), tmap.end(), DumpTypes);
 444 }
 445
 446 // vim: sw=2 ai