LLVM API Documentation
00001 //===-- SlotCalculator.cpp - Calculate what slots values land in ----------===// 00002 // 00003 // The LLVM Compiler Infrastructure 00004 // 00005 // This file was developed by the LLVM research group and is distributed under 00006 // the University of Illinois Open Source License. See LICENSE.TXT for details. 00007 // 00008 //===----------------------------------------------------------------------===// 00009 // 00010 // This file implements a useful analysis step to figure out what numbered slots 00011 // values in a program will land in (keeping track of per plane information). 00012 // 00013 // This is used when writing a file to disk, either in bytecode or assembly. 00014 // 00015 //===----------------------------------------------------------------------===// 00016 00017 #include "SlotCalculator.h" 00018 #include "llvm/Constants.h" 00019 #include "llvm/DerivedTypes.h" 00020 #include "llvm/Function.h" 00021 #include "llvm/InlineAsm.h" 00022 #include "llvm/Instructions.h" 00023 #include "llvm/Module.h" 00024 #include "llvm/SymbolTable.h" 00025 #include "llvm/Type.h" 00026 #include "llvm/Analysis/ConstantsScanner.h" 00027 #include "llvm/ADT/PostOrderIterator.h" 00028 #include "llvm/ADT/STLExtras.h" 00029 #include <algorithm> 00030 #include <functional> 00031 using namespace llvm; 00032 00033 #if 0 00034 #include <iostream> 00035 #define SC_DEBUG(X) std::cerr << X 00036 #else 00037 #define SC_DEBUG(X) 00038 #endif 00039 00040 SlotCalculator::SlotCalculator(const Module *M ) { 00041 ModuleContainsAllFunctionConstants = false; 00042 ModuleTypeLevel = 0; 00043 TheModule = M; 00044 00045 // Preload table... Make sure that all of the primitive types are in the table 00046 // and that their Primitive ID is equal to their slot # 00047 // 00048 SC_DEBUG("Inserting primitive types:\n"); 00049 for (unsigned i = 0; i < Type::FirstDerivedTyID; ++i) { 00050 assert(Type::getPrimitiveType((Type::TypeID)i)); 00051 insertType(Type::getPrimitiveType((Type::TypeID)i), true); 00052 } 00053 00054 if (M == 0) return; // Empty table... 00055 processModule(); 00056 } 00057 00058 SlotCalculator::SlotCalculator(const Function *M ) { 00059 ModuleContainsAllFunctionConstants = false; 00060 TheModule = M ? M->getParent() : 0; 00061 00062 // Preload table... Make sure that all of the primitive types are in the table 00063 // and that their Primitive ID is equal to their slot # 00064 // 00065 SC_DEBUG("Inserting primitive types:\n"); 00066 for (unsigned i = 0; i < Type::FirstDerivedTyID; ++i) { 00067 assert(Type::getPrimitiveType((Type::TypeID)i)); 00068 insertType(Type::getPrimitiveType((Type::TypeID)i), true); 00069 } 00070 00071 if (TheModule == 0) return; // Empty table... 00072 00073 processModule(); // Process module level stuff 00074 incorporateFunction(M); // Start out in incorporated state 00075 } 00076 00077 unsigned SlotCalculator::getGlobalSlot(const Value *V) const { 00078 assert(!CompactionTable.empty() && 00079 "This method can only be used when compaction is enabled!"); 00080 std::map<const Value*, unsigned>::const_iterator I = NodeMap.find(V); 00081 assert(I != NodeMap.end() && "Didn't find global slot entry!"); 00082 return I->second; 00083 } 00084 00085 unsigned SlotCalculator::getGlobalSlot(const Type* T) const { 00086 std::map<const Type*, unsigned>::const_iterator I = TypeMap.find(T); 00087 assert(I != TypeMap.end() && "Didn't find global slot entry!"); 00088 return I->second; 00089 } 00090 00091 SlotCalculator::TypePlane &SlotCalculator::getPlane(unsigned Plane) { 00092 if (CompactionTable.empty()) { // No compaction table active? 00093 // fall out 00094 } else if (!CompactionTable[Plane].empty()) { // Compaction table active. 00095 assert(Plane < CompactionTable.size()); 00096 return CompactionTable[Plane]; 00097 } else { 00098 // Final case: compaction table active, but this plane is not 00099 // compactified. If the type plane is compactified, unmap back to the 00100 // global type plane corresponding to "Plane". 00101 if (!CompactionTypes.empty()) { 00102 const Type *Ty = CompactionTypes[Plane]; 00103 TypeMapType::iterator It = TypeMap.find(Ty); 00104 assert(It != TypeMap.end() && "Type not in global constant map?"); 00105 Plane = It->second; 00106 } 00107 } 00108 00109 // Okay we are just returning an entry out of the main Table. Make sure the 00110 // plane exists and return it. 00111 if (Plane >= Table.size()) 00112 Table.resize(Plane+1); 00113 return Table[Plane]; 00114 } 00115 00116 // processModule - Process all of the module level function declarations and 00117 // types that are available. 00118 // 00119 void SlotCalculator::processModule() { 00120 SC_DEBUG("begin processModule!\n"); 00121 00122 // Add all of the global variables to the value table... 00123 // 00124 for (Module::const_global_iterator I = TheModule->global_begin(), 00125 E = TheModule->global_end(); I != E; ++I) 00126 getOrCreateSlot(I); 00127 00128 // Scavenge the types out of the functions, then add the functions themselves 00129 // to the value table... 00130 // 00131 for (Module::const_iterator I = TheModule->begin(), E = TheModule->end(); 00132 I != E; ++I) 00133 getOrCreateSlot(I); 00134 00135 // Add all of the module level constants used as initializers 00136 // 00137 for (Module::const_global_iterator I = TheModule->global_begin(), 00138 E = TheModule->global_end(); I != E; ++I) 00139 if (I->hasInitializer()) 00140 getOrCreateSlot(I->getInitializer()); 00141 00142 // Now that all global constants have been added, rearrange constant planes 00143 // that contain constant strings so that the strings occur at the start of the 00144 // plane, not somewhere in the middle. 00145 // 00146 for (unsigned plane = 0, e = Table.size(); plane != e; ++plane) { 00147 if (const ArrayType *AT = dyn_cast<ArrayType>(Types[plane])) 00148 if (AT->getElementType() == Type::SByteTy || 00149 AT->getElementType() == Type::UByteTy) { 00150 TypePlane &Plane = Table[plane]; 00151 unsigned FirstNonStringID = 0; 00152 for (unsigned i = 0, e = Plane.size(); i != e; ++i) 00153 if (isa<ConstantAggregateZero>(Plane[i]) || 00154 (isa<ConstantArray>(Plane[i]) && 00155 cast<ConstantArray>(Plane[i])->isString())) { 00156 // Check to see if we have to shuffle this string around. If not, 00157 // don't do anything. 00158 if (i != FirstNonStringID) { 00159 // Swap the plane entries.... 00160 std::swap(Plane[i], Plane[FirstNonStringID]); 00161 00162 // Keep the NodeMap up to date. 00163 NodeMap[Plane[i]] = i; 00164 NodeMap[Plane[FirstNonStringID]] = FirstNonStringID; 00165 } 00166 ++FirstNonStringID; 00167 } 00168 } 00169 } 00170 00171 // Scan all of the functions for their constants, which allows us to emit 00172 // more compact modules. This is optional, and is just used to compactify 00173 // the constants used by different functions together. 00174 // 00175 // This functionality tends to produce smaller bytecode files. This should 00176 // not be used in the future by clients that want to, for example, build and 00177 // emit functions on the fly. For now, however, it is unconditionally 00178 // enabled. 00179 ModuleContainsAllFunctionConstants = true; 00180 00181 SC_DEBUG("Inserting function constants:\n"); 00182 for (Module::const_iterator F = TheModule->begin(), E = TheModule->end(); 00183 F != E; ++F) { 00184 for (const_inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) { 00185 for (User::const_op_iterator OI = I->op_begin(), E = I->op_end(); 00186 OI != E; ++OI) { 00187 if ((isa<Constant>(*OI) && !isa<GlobalValue>(*OI)) || 00188 isa<InlineAsm>(*OI)) 00189 getOrCreateSlot(*OI); 00190 } 00191 getOrCreateSlot(I->getType()); 00192 } 00193 processSymbolTableConstants(&F->getSymbolTable()); 00194 } 00195 00196 // Insert constants that are named at module level into the slot pool so that 00197 // the module symbol table can refer to them... 00198 SC_DEBUG("Inserting SymbolTable values:\n"); 00199 processSymbolTable(&TheModule->getSymbolTable()); 00200 00201 // Now that we have collected together all of the information relevant to the 00202 // module, compactify the type table if it is particularly big and outputting 00203 // a bytecode file. The basic problem we run into is that some programs have 00204 // a large number of types, which causes the type field to overflow its size, 00205 // which causes instructions to explode in size (particularly call 00206 // instructions). To avoid this behavior, we "sort" the type table so that 00207 // all non-value types are pushed to the end of the type table, giving nice 00208 // low numbers to the types that can be used by instructions, thus reducing 00209 // the amount of explodage we suffer. 00210 if (Types.size() >= 64) { 00211 unsigned FirstNonValueTypeID = 0; 00212 for (unsigned i = 0, e = Types.size(); i != e; ++i) 00213 if (Types[i]->isFirstClassType() || Types[i]->isPrimitiveType()) { 00214 // Check to see if we have to shuffle this type around. If not, don't 00215 // do anything. 00216 if (i != FirstNonValueTypeID) { 00217 // Swap the type ID's. 00218 std::swap(Types[i], Types[FirstNonValueTypeID]); 00219 00220 // Keep the TypeMap up to date. 00221 TypeMap[Types[i]] = i; 00222 TypeMap[Types[FirstNonValueTypeID]] = FirstNonValueTypeID; 00223 00224 // When we move a type, make sure to move its value plane as needed. 00225 if (Table.size() > FirstNonValueTypeID) { 00226 if (Table.size() <= i) Table.resize(i+1); 00227 std::swap(Table[i], Table[FirstNonValueTypeID]); 00228 } 00229 } 00230 ++FirstNonValueTypeID; 00231 } 00232 } 00233 00234 SC_DEBUG("end processModule!\n"); 00235 } 00236 00237 // processSymbolTable - Insert all of the values in the specified symbol table 00238 // into the values table... 00239 // 00240 void SlotCalculator::processSymbolTable(const SymbolTable *ST) { 00241 // Do the types first. 00242 for (SymbolTable::type_const_iterator TI = ST->type_begin(), 00243 TE = ST->type_end(); TI != TE; ++TI ) 00244 getOrCreateSlot(TI->second); 00245 00246 // Now do the values. 00247 for (SymbolTable::plane_const_iterator PI = ST->plane_begin(), 00248 PE = ST->plane_end(); PI != PE; ++PI) 00249 for (SymbolTable::value_const_iterator VI = PI->second.begin(), 00250 VE = PI->second.end(); VI != VE; ++VI) 00251 getOrCreateSlot(VI->second); 00252 } 00253 00254 void SlotCalculator::processSymbolTableConstants(const SymbolTable *ST) { 00255 // Do the types first 00256 for (SymbolTable::type_const_iterator TI = ST->type_begin(), 00257 TE = ST->type_end(); TI != TE; ++TI ) 00258 getOrCreateSlot(TI->second); 00259 00260 // Now do the constant values in all planes 00261 for (SymbolTable::plane_const_iterator PI = ST->plane_begin(), 00262 PE = ST->plane_end(); PI != PE; ++PI) 00263 for (SymbolTable::value_const_iterator VI = PI->second.begin(), 00264 VE = PI->second.end(); VI != VE; ++VI) 00265 if (isa<Constant>(VI->second) && 00266 !isa<GlobalValue>(VI->second)) 00267 getOrCreateSlot(VI->second); 00268 } 00269 00270 00271 void SlotCalculator::incorporateFunction(const Function *F) { 00272 assert((ModuleLevel.size() == 0 || 00273 ModuleTypeLevel == 0) && "Module already incorporated!"); 00274 00275 SC_DEBUG("begin processFunction!\n"); 00276 00277 // If we emitted all of the function constants, build a compaction table. 00278 if (ModuleContainsAllFunctionConstants) 00279 buildCompactionTable(F); 00280 00281 // Update the ModuleLevel entries to be accurate. 00282 ModuleLevel.resize(getNumPlanes()); 00283 for (unsigned i = 0, e = getNumPlanes(); i != e; ++i) 00284 ModuleLevel[i] = getPlane(i).size(); 00285 ModuleTypeLevel = Types.size(); 00286 00287 // Iterate over function arguments, adding them to the value table... 00288 for(Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; ++I) 00289 getOrCreateSlot(I); 00290 00291 if (!ModuleContainsAllFunctionConstants) { 00292 // Iterate over all of the instructions in the function, looking for 00293 // constant values that are referenced. Add these to the value pools 00294 // before any nonconstant values. This will be turned into the constant 00295 // pool for the bytecode writer. 00296 // 00297 00298 // Emit all of the constants that are being used by the instructions in 00299 // the function... 00300 for (constant_iterator CI = constant_begin(F), CE = constant_end(F); 00301 CI != CE; ++CI) 00302 getOrCreateSlot(*CI); 00303 00304 // If there is a symbol table, it is possible that the user has names for 00305 // constants that are not being used. In this case, we will have problems 00306 // if we don't emit the constants now, because otherwise we will get 00307 // symbol table references to constants not in the output. Scan for these 00308 // constants now. 00309 // 00310 processSymbolTableConstants(&F->getSymbolTable()); 00311 } 00312 00313 SC_DEBUG("Inserting Instructions:\n"); 00314 00315 // Add all of the instructions to the type planes... 00316 for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB) { 00317 getOrCreateSlot(BB); 00318 for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E; ++I) { 00319 getOrCreateSlot(I); 00320 } 00321 } 00322 00323 // If we are building a compaction table, prune out planes that do not benefit 00324 // from being compactified. 00325 if (!CompactionTable.empty()) 00326 pruneCompactionTable(); 00327 00328 SC_DEBUG("end processFunction!\n"); 00329 } 00330 00331 void SlotCalculator::purgeFunction() { 00332 assert((ModuleLevel.size() != 0 || 00333 ModuleTypeLevel != 0) && "Module not incorporated!"); 00334 unsigned NumModuleTypes = ModuleLevel.size(); 00335 00336 SC_DEBUG("begin purgeFunction!\n"); 00337 00338 // First, free the compaction map if used. 00339 CompactionNodeMap.clear(); 00340 CompactionTypeMap.clear(); 00341 00342 // Next, remove values from existing type planes 00343 for (unsigned i = 0; i != NumModuleTypes; ++i) { 00344 // Size of plane before function came 00345 unsigned ModuleLev = getModuleLevel(i); 00346 assert(int(ModuleLev) >= 0 && "BAD!"); 00347 00348 TypePlane &Plane = getPlane(i); 00349 00350 assert(ModuleLev <= Plane.size() && "module levels higher than elements?"); 00351 while (Plane.size() != ModuleLev) { 00352 assert(!isa<GlobalValue>(Plane.back()) && 00353 "Functions cannot define globals!"); 00354 NodeMap.erase(Plane.back()); // Erase from nodemap 00355 Plane.pop_back(); // Shrink plane 00356 } 00357 } 00358 00359 // We don't need this state anymore, free it up. 00360 ModuleLevel.clear(); 00361 ModuleTypeLevel = 0; 00362 00363 // Finally, remove any type planes defined by the function... 00364 CompactionTypes.clear(); 00365 if (!CompactionTable.empty()) { 00366 CompactionTable.clear(); 00367 } else { 00368 while (Table.size() > NumModuleTypes) { 00369 TypePlane &Plane = Table.back(); 00370 SC_DEBUG("Removing Plane " << (Table.size()-1) << " of size " 00371 << Plane.size() << "\n"); 00372 while (Plane.size()) { 00373 assert(!isa<GlobalValue>(Plane.back()) && 00374 "Functions cannot define globals!"); 00375 NodeMap.erase(Plane.back()); // Erase from nodemap 00376 Plane.pop_back(); // Shrink plane 00377 } 00378 00379 Table.pop_back(); // Nuke the plane, we don't like it. 00380 } 00381 } 00382 00383 SC_DEBUG("end purgeFunction!\n"); 00384 } 00385 00386 static inline bool hasNullValue(const Type *Ty) { 00387 return Ty != Type::LabelTy && Ty != Type::VoidTy && !isa<OpaqueType>(Ty); 00388 } 00389 00390 /// getOrCreateCompactionTableSlot - This method is used to build up the initial 00391 /// approximation of the compaction table. 00392 unsigned SlotCalculator::getOrCreateCompactionTableSlot(const Value *V) { 00393 std::map<const Value*, unsigned>::iterator I = 00394 CompactionNodeMap.lower_bound(V); 00395 if (I != CompactionNodeMap.end() && I->first == V) 00396 return I->second; // Already exists? 00397 00398 // Make sure the type is in the table. 00399 unsigned Ty; 00400 if (!CompactionTypes.empty()) 00401 Ty = getOrCreateCompactionTableSlot(V->getType()); 00402 else // If the type plane was decompactified, use the global plane ID 00403 Ty = getSlot(V->getType()); 00404 if (CompactionTable.size() <= Ty) 00405 CompactionTable.resize(Ty+1); 00406 00407 TypePlane &TyPlane = CompactionTable[Ty]; 00408 00409 // Make sure to insert the null entry if the thing we are inserting is not a 00410 // null constant. 00411 if (TyPlane.empty() && hasNullValue(V->getType())) { 00412 Value *ZeroInitializer = Constant::getNullValue(V->getType()); 00413 if (V != ZeroInitializer) { 00414 TyPlane.push_back(ZeroInitializer); 00415 CompactionNodeMap[ZeroInitializer] = 0; 00416 } 00417 } 00418 00419 unsigned SlotNo = TyPlane.size(); 00420 TyPlane.push_back(V); 00421 CompactionNodeMap.insert(std::make_pair(V, SlotNo)); 00422 return SlotNo; 00423 } 00424 00425 /// getOrCreateCompactionTableSlot - This method is used to build up the initial 00426 /// approximation of the compaction table. 00427 unsigned SlotCalculator::getOrCreateCompactionTableSlot(const Type *T) { 00428 std::map<const Type*, unsigned>::iterator I = 00429 CompactionTypeMap.lower_bound(T); 00430 if (I != CompactionTypeMap.end() && I->first == T) 00431 return I->second; // Already exists? 00432 00433 unsigned SlotNo = CompactionTypes.size(); 00434 SC_DEBUG("Inserting Compaction Type #" << SlotNo << ": " << T << "\n"); 00435 CompactionTypes.push_back(T); 00436 CompactionTypeMap.insert(std::make_pair(T, SlotNo)); 00437 return SlotNo; 00438 } 00439 00440 /// buildCompactionTable - Since all of the function constants and types are 00441 /// stored in the module-level constant table, we don't need to emit a function 00442 /// constant table. Also due to this, the indices for various constants and 00443 /// types might be very large in large programs. In order to avoid blowing up 00444 /// the size of instructions in the bytecode encoding, we build a compaction 00445 /// table, which defines a mapping from function-local identifiers to global 00446 /// identifiers. 00447 void SlotCalculator::buildCompactionTable(const Function *F) { 00448 assert(CompactionNodeMap.empty() && "Compaction table already built!"); 00449 assert(CompactionTypeMap.empty() && "Compaction types already built!"); 00450 // First step, insert the primitive types. 00451 CompactionTable.resize(Type::LastPrimitiveTyID+1); 00452 for (unsigned i = 0; i <= Type::LastPrimitiveTyID; ++i) { 00453 const Type *PrimTy = Type::getPrimitiveType((Type::TypeID)i); 00454 CompactionTypes.push_back(PrimTy); 00455 CompactionTypeMap[PrimTy] = i; 00456 } 00457 00458 // Next, include any types used by function arguments. 00459 for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end(); 00460 I != E; ++I) 00461 getOrCreateCompactionTableSlot(I->getType()); 00462 00463 // Next, find all of the types and values that are referred to by the 00464 // instructions in the function. 00465 for (const_inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) { 00466 getOrCreateCompactionTableSlot(I->getType()); 00467 for (unsigned op = 0, e = I->getNumOperands(); op != e; ++op) 00468 if (isa<Constant>(I->getOperand(op)) || isa<InlineAsm>(I->getOperand(op))) 00469 getOrCreateCompactionTableSlot(I->getOperand(op)); 00470 } 00471 00472 // Do the types in the symbol table 00473 const SymbolTable &ST = F->getSymbolTable(); 00474 for (SymbolTable::type_const_iterator TI = ST.type_begin(), 00475 TE = ST.type_end(); TI != TE; ++TI) 00476 getOrCreateCompactionTableSlot(TI->second); 00477 00478 // Now do the constants and global values 00479 for (SymbolTable::plane_const_iterator PI = ST.plane_begin(), 00480 PE = ST.plane_end(); PI != PE; ++PI) 00481 for (SymbolTable::value_const_iterator VI = PI->second.begin(), 00482 VE = PI->second.end(); VI != VE; ++VI) 00483 if (isa<Constant>(VI->second) && !isa<GlobalValue>(VI->second)) 00484 getOrCreateCompactionTableSlot(VI->second); 00485 00486 // Now that we have all of the values in the table, and know what types are 00487 // referenced, make sure that there is at least the zero initializer in any 00488 // used type plane. Since the type was used, we will be emitting instructions 00489 // to the plane even if there are no constants in it. 00490 CompactionTable.resize(CompactionTypes.size()); 00491 for (unsigned i = 0, e = CompactionTable.size(); i != e; ++i) 00492 if (CompactionTable[i].empty() && (i != Type::VoidTyID) && 00493 i != Type::LabelTyID) { 00494 const Type *Ty = CompactionTypes[i]; 00495 SC_DEBUG("Getting Null Value #" << i << " for Type " << Ty << "\n"); 00496 assert(Ty->getTypeID() != Type::VoidTyID); 00497 assert(Ty->getTypeID() != Type::LabelTyID); 00498 getOrCreateCompactionTableSlot(Constant::getNullValue(Ty)); 00499 } 00500 00501 // Okay, now at this point, we have a legal compaction table. Since we want 00502 // to emit the smallest possible binaries, do not compactify the type plane if 00503 // it will not save us anything. Because we have not yet incorporated the 00504 // function body itself yet, we don't know whether or not it's a good idea to 00505 // compactify other planes. We will defer this decision until later. 00506 TypeList &GlobalTypes = Types; 00507 00508 // All of the values types will be scrunched to the start of the types plane 00509 // of the global table. Figure out just how many there are. 00510 assert(!GlobalTypes.empty() && "No global types???"); 00511 unsigned NumFCTypes = GlobalTypes.size()-1; 00512 while (!GlobalTypes[NumFCTypes]->isFirstClassType()) 00513 --NumFCTypes; 00514 00515 // If there are fewer that 64 types, no instructions will be exploded due to 00516 // the size of the type operands. Thus there is no need to compactify types. 00517 // Also, if the compaction table contains most of the entries in the global 00518 // table, there really is no reason to compactify either. 00519 if (NumFCTypes < 64) { 00520 // Decompactifying types is tricky, because we have to move type planes all 00521 // over the place. At least we don't need to worry about updating the 00522 // CompactionNodeMap for non-types though. 00523 std::vector<TypePlane> TmpCompactionTable; 00524 std::swap(CompactionTable, TmpCompactionTable); 00525 TypeList TmpTypes; 00526 std::swap(TmpTypes, CompactionTypes); 00527 00528 // Move each plane back over to the uncompactified plane 00529 while (!TmpTypes.empty()) { 00530 const Type *Ty = TmpTypes.back(); 00531 TmpTypes.pop_back(); 00532 CompactionTypeMap.erase(Ty); // Decompactify type! 00533 00534 // Find the global slot number for this type. 00535 int TySlot = getSlot(Ty); 00536 assert(TySlot != -1 && "Type doesn't exist in global table?"); 00537 00538 // Now we know where to put the compaction table plane. 00539 if (CompactionTable.size() <= unsigned(TySlot)) 00540 CompactionTable.resize(TySlot+1); 00541 // Move the plane back into the compaction table. 00542 std::swap(CompactionTable[TySlot], TmpCompactionTable[TmpTypes.size()]); 00543 00544 // And remove the empty plane we just moved in. 00545 TmpCompactionTable.pop_back(); 00546 } 00547 } 00548 } 00549 00550 00551 /// pruneCompactionTable - Once the entire function being processed has been 00552 /// incorporated into the current compaction table, look over the compaction 00553 /// table and check to see if there are any values whose compaction will not 00554 /// save us any space in the bytecode file. If compactifying these values 00555 /// serves no purpose, then we might as well not even emit the compactification 00556 /// information to the bytecode file, saving a bit more space. 00557 /// 00558 /// Note that the type plane has already been compactified if possible. 00559 /// 00560 void SlotCalculator::pruneCompactionTable() { 00561 TypeList &TyPlane = CompactionTypes; 00562 for (unsigned ctp = 0, e = CompactionTable.size(); ctp != e; ++ctp) 00563 if (!CompactionTable[ctp].empty()) { 00564 TypePlane &CPlane = CompactionTable[ctp]; 00565 unsigned GlobalSlot = ctp; 00566 if (!TyPlane.empty()) 00567 GlobalSlot = getGlobalSlot(TyPlane[ctp]); 00568 00569 if (GlobalSlot >= Table.size()) 00570 Table.resize(GlobalSlot+1); 00571 TypePlane &GPlane = Table[GlobalSlot]; 00572 00573 unsigned ModLevel = getModuleLevel(ctp); 00574 unsigned NumFunctionObjs = CPlane.size()-ModLevel; 00575 00576 // If the maximum index required if all entries in this plane were merged 00577 // into the global plane is less than 64, go ahead and eliminate the 00578 // plane. 00579 bool PrunePlane = GPlane.size() + NumFunctionObjs < 64; 00580 00581 // If there are no function-local values defined, and the maximum 00582 // referenced global entry is less than 64, we don't need to compactify. 00583 if (!PrunePlane && NumFunctionObjs == 0) { 00584 unsigned MaxIdx = 0; 00585 for (unsigned i = 0; i != ModLevel; ++i) { 00586 unsigned Idx = NodeMap[CPlane[i]]; 00587 if (Idx > MaxIdx) MaxIdx = Idx; 00588 } 00589 PrunePlane = MaxIdx < 64; 00590 } 00591 00592 // Ok, finally, if we decided to prune this plane out of the compaction 00593 // table, do so now. 00594 if (PrunePlane) { 00595 TypePlane OldPlane; 00596 std::swap(OldPlane, CPlane); 00597 00598 // Loop over the function local objects, relocating them to the global 00599 // table plane. 00600 for (unsigned i = ModLevel, e = OldPlane.size(); i != e; ++i) { 00601 const Value *V = OldPlane[i]; 00602 CompactionNodeMap.erase(V); 00603 assert(NodeMap.count(V) == 0 && "Value already in table??"); 00604 getOrCreateSlot(V); 00605 } 00606 00607 // For compactified global values, just remove them from the compaction 00608 // node map. 00609 for (unsigned i = 0; i != ModLevel; ++i) 00610 CompactionNodeMap.erase(OldPlane[i]); 00611 00612 // Update the new modulelevel for this plane. 00613 assert(ctp < ModuleLevel.size() && "Cannot set modulelevel!"); 00614 ModuleLevel[ctp] = GPlane.size()-NumFunctionObjs; 00615 assert((int)ModuleLevel[ctp] >= 0 && "Bad computation!"); 00616 } 00617 } 00618 } 00619 00620 /// Determine if the compaction table is actually empty. Because the 00621 /// compaction table always includes the primitive type planes, we 00622 /// can't just check getCompactionTable().size() because it will never 00623 /// be zero. Furthermore, the ModuleLevel factors into whether a given 00624 /// plane is empty or not. This function does the necessary computation 00625 /// to determine if its actually empty. 00626 bool SlotCalculator::CompactionTableIsEmpty() const { 00627 // Check a degenerate case, just in case. 00628 if (CompactionTable.size() == 0) return true; 00629 00630 // Check each plane 00631 for (unsigned i = 0, e = CompactionTable.size(); i < e; ++i) { 00632 // If the plane is not empty 00633 if (!CompactionTable[i].empty()) { 00634 // If the module level is non-zero then at least the 00635 // first element of the plane is valid and therefore not empty. 00636 unsigned End = getModuleLevel(i); 00637 if (End != 0) 00638 return false; 00639 } 00640 } 00641 // All the compaction table planes are empty so the table is 00642 // considered empty too. 00643 return true; 00644 } 00645 00646 int SlotCalculator::getSlot(const Value *V) const { 00647 // If there is a CompactionTable active... 00648 if (!CompactionNodeMap.empty()) { 00649 std::map<const Value*, unsigned>::const_iterator I = 00650 CompactionNodeMap.find(V); 00651 if (I != CompactionNodeMap.end()) 00652 return (int)I->second; 00653 // Otherwise, if it's not in the compaction table, it must be in a 00654 // non-compactified plane. 00655 } 00656 00657 std::map<const Value*, unsigned>::const_iterator I = NodeMap.find(V); 00658 if (I != NodeMap.end()) 00659 return (int)I->second; 00660 00661 return -1; 00662 } 00663 00664 int SlotCalculator::getSlot(const Type*T) const { 00665 // If there is a CompactionTable active... 00666 if (!CompactionTypeMap.empty()) { 00667 std::map<const Type*, unsigned>::const_iterator I = 00668 CompactionTypeMap.find(T); 00669 if (I != CompactionTypeMap.end()) 00670 return (int)I->second; 00671 // Otherwise, if it's not in the compaction table, it must be in a 00672 // non-compactified plane. 00673 } 00674 00675 std::map<const Type*, unsigned>::const_iterator I = TypeMap.find(T); 00676 if (I != TypeMap.end()) 00677 return (int)I->second; 00678 00679 return -1; 00680 } 00681 00682 int SlotCalculator::getOrCreateSlot(const Value *V) { 00683 if (V->getType() == Type::VoidTy) return -1; 00684 00685 int SlotNo = getSlot(V); // Check to see if it's already in! 00686 if (SlotNo != -1) return SlotNo; 00687 00688 if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) 00689 assert(GV->getParent() != 0 && "Global not embedded into a module!"); 00690 00691 if (!isa<GlobalValue>(V)) // Initializers for globals are handled explicitly 00692 if (const Constant *C = dyn_cast<Constant>(V)) { 00693 assert(CompactionNodeMap.empty() && 00694 "All needed constants should be in the compaction map already!"); 00695 00696 // Do not index the characters that make up constant strings. We emit 00697 // constant strings as special entities that don't require their 00698 // individual characters to be emitted. 00699 if (!isa<ConstantArray>(C) || !cast<ConstantArray>(C)->isString()) { 00700 // This makes sure that if a constant has uses (for example an array of 00701 // const ints), that they are inserted also. 00702 // 00703 for (User::const_op_iterator I = C->op_begin(), E = C->op_end(); 00704 I != E; ++I) 00705 getOrCreateSlot(*I); 00706 } else { 00707 assert(ModuleLevel.empty() && 00708 "How can a constant string be directly accessed in a function?"); 00709 // Otherwise, if we are emitting a bytecode file and this IS a string, 00710 // remember it. 00711 if (!C->isNullValue()) 00712 ConstantStrings.push_back(cast<ConstantArray>(C)); 00713 } 00714 } 00715 00716 return insertValue(V); 00717 } 00718 00719 int SlotCalculator::getOrCreateSlot(const Type* T) { 00720 int SlotNo = getSlot(T); // Check to see if it's already in! 00721 if (SlotNo != -1) return SlotNo; 00722 return insertType(T); 00723 } 00724 00725 int SlotCalculator::insertValue(const Value *D, bool dontIgnore) { 00726 assert(D && "Can't insert a null value!"); 00727 assert(getSlot(D) == -1 && "Value is already in the table!"); 00728 00729 // If we are building a compaction map, and if this plane is being compacted, 00730 // insert the value into the compaction map, not into the global map. 00731 if (!CompactionNodeMap.empty()) { 00732 if (D->getType() == Type::VoidTy) return -1; // Do not insert void values 00733 assert(!isa<Constant>(D) && 00734 "Types, constants, and globals should be in global table!"); 00735 00736 int Plane = getSlot(D->getType()); 00737 assert(Plane != -1 && CompactionTable.size() > (unsigned)Plane && 00738 "Didn't find value type!"); 00739 if (!CompactionTable[Plane].empty()) 00740 return getOrCreateCompactionTableSlot(D); 00741 } 00742 00743 // If this node does not contribute to a plane, or if the node has a 00744 // name and we don't want names, then ignore the silly node... Note that types 00745 // do need slot numbers so that we can keep track of where other values land. 00746 // 00747 if (!dontIgnore) // Don't ignore nonignorables! 00748 if (D->getType() == Type::VoidTy ) { // Ignore void type nodes 00749 SC_DEBUG("ignored value " << *D << "\n"); 00750 return -1; // We do need types unconditionally though 00751 } 00752 00753 // Okay, everything is happy, actually insert the silly value now... 00754 return doInsertValue(D); 00755 } 00756 00757 int SlotCalculator::insertType(const Type *Ty, bool dontIgnore) { 00758 assert(Ty && "Can't insert a null type!"); 00759 assert(getSlot(Ty) == -1 && "Type is already in the table!"); 00760 00761 // If we are building a compaction map, and if this plane is being compacted, 00762 // insert the value into the compaction map, not into the global map. 00763 if (!CompactionTypeMap.empty()) { 00764 getOrCreateCompactionTableSlot(Ty); 00765 } 00766 00767 // Insert the current type before any subtypes. This is important because 00768 // recursive types elements are inserted in a bottom up order. Changing 00769 // this here can break things. For example: 00770 // 00771 // global { \2 * } { { \2 }* null } 00772 // 00773 int ResultSlot = doInsertType(Ty); 00774 SC_DEBUG(" Inserted type: " << Ty->getDescription() << " slot=" << 00775 ResultSlot << "\n"); 00776 00777 // Loop over any contained types in the definition... in post 00778 // order. 00779 for (po_iterator<const Type*> I = po_begin(Ty), E = po_end(Ty); 00780 I != E; ++I) { 00781 if (*I != Ty) { 00782 const Type *SubTy = *I; 00783 // If we haven't seen this sub type before, add it to our type table! 00784 if (getSlot(SubTy) == -1) { 00785 SC_DEBUG(" Inserting subtype: " << SubTy->getDescription() << "\n"); 00786 doInsertType(SubTy); 00787 SC_DEBUG(" Inserted subtype: " << SubTy->getDescription() << "\n"); 00788 } 00789 } 00790 } 00791 return ResultSlot; 00792 } 00793 00794 // doInsertValue - This is a small helper function to be called only 00795 // be insertValue. 00796 // 00797 int SlotCalculator::doInsertValue(const Value *D) { 00798 const Type *Typ = D->getType(); 00799 unsigned Ty; 00800 00801 // Used for debugging DefSlot=-1 assertion... 00802 //if (Typ == Type::TypeTy) 00803 // cerr << "Inserting type '" << cast<Type>(D)->getDescription() << "'!\n"; 00804 00805 if (Typ->isDerivedType()) { 00806 int ValSlot; 00807 if (CompactionTable.empty()) 00808 ValSlot = getSlot(Typ); 00809 else 00810 ValSlot = getGlobalSlot(Typ); 00811 if (ValSlot == -1) { // Have we already entered this type? 00812 // Nope, this is the first we have seen the type, process it. 00813 ValSlot = insertType(Typ, true); 00814 assert(ValSlot != -1 && "ProcessType returned -1 for a type?"); 00815 } 00816 Ty = (unsigned)ValSlot; 00817 } else { 00818 Ty = Typ->getTypeID(); 00819 } 00820 00821 if (Table.size() <= Ty) // Make sure we have the type plane allocated... 00822 Table.resize(Ty+1, TypePlane()); 00823 00824 // If this is the first value to get inserted into the type plane, make sure 00825 // to insert the implicit null value... 00826 if (Table[Ty].empty() && hasNullValue(Typ)) { 00827 Value *ZeroInitializer = Constant::getNullValue(Typ); 00828 00829 // If we are pushing zeroinit, it will be handled below. 00830 if (D != ZeroInitializer) { 00831 Table[Ty].push_back(ZeroInitializer); 00832 NodeMap[ZeroInitializer] = 0; 00833 } 00834 } 00835 00836 // Insert node into table and NodeMap... 00837 unsigned DestSlot = NodeMap[D] = Table[Ty].size(); 00838 Table[Ty].push_back(D); 00839 00840 SC_DEBUG(" Inserting value [" << Ty << "] = " << D << " slot=" << 00841 DestSlot << " ["); 00842 // G = Global, C = Constant, T = Type, F = Function, o = other 00843 SC_DEBUG((isa<GlobalVariable>(D) ? "G" : (isa<Constant>(D) ? "C" : 00844 (isa<Function>(D) ? "F" : "o")))); 00845 SC_DEBUG("]\n"); 00846 return (int)DestSlot; 00847 } 00848 00849 // doInsertType - This is a small helper function to be called only 00850 // be insertType. 00851 // 00852 int SlotCalculator::doInsertType(const Type *Ty) { 00853 00854 // Insert node into table and NodeMap... 00855 unsigned DestSlot = TypeMap[Ty] = Types.size(); 00856 Types.push_back(Ty); 00857 00858 SC_DEBUG(" Inserting type [" << DestSlot << "] = " << Ty << "\n" ); 00859 return (int)DestSlot; 00860 } 00861