lto.cpp revision 30235dad4b77ed83ca985030aff4fb4767551e5d
16f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org//===-lto.cpp - LLVM Link Time Optimizer ----------------------------------===// 26f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org// 36f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org// The LLVM Compiler Infrastructure 46f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org// 56f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org// This file was developed by Devang Patel and is distributed under 66f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org// the University of Illinois Open Source License. See LICENSE.TXT for details. 76f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org// 86f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org//===----------------------------------------------------------------------===// 96f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org// 106f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org// This file implementes link time optimization library. This library is 116f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org// intended to be used by linker to optimize code at link time. 126f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org// 136f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org//===----------------------------------------------------------------------===// 146f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 156f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Module.h" 166f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/PassManager.h" 176f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Linker.h" 186f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Constants.h" 196f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/DerivedTypes.h" 206f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/SymbolTable.h" 216f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Bytecode/Reader.h" 226f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Bytecode/Writer.h" 236f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Support/CommandLine.h" 246f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Support/FileUtilities.h" 256f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Support/SystemUtils.h" 266f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Support/Mangler.h" 276f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/System/Program.h" 286f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/System/Signals.h" 296f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Analysis/Passes.h" 306f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Analysis/Verifier.h" 316f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Target/SubtargetFeature.h" 326f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Target/TargetData.h" 336f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Target/TargetMachine.h" 346f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Target/TargetMachineRegistry.h" 356f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Transforms/IPO.h" 366f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Transforms/Scalar.h" 376f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/Analysis/LoadValueNumbering.h" 386f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include "llvm/LinkTimeOptimizer.h" 396f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include <fstream> 406f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org#include <iostream> 416f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 426f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.orgusing namespace llvm; 436f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 446f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.orgextern "C" 456f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.orgllvm::LinkTimeOptimizer *createLLVMOptimizer() 466f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org{ 476f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org llvm::LinkTimeOptimizer *l = new llvm::LinkTimeOptimizer(); 486f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org return l; 496f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org} 506f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 516f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 526f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 536f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org/// If symbol is not used then make it internal and let optimizer takes 546f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org/// care of it. 556f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.orgvoid LLVMSymbol::mayBeNotUsed() { 566f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org gv->setLinkage(GlobalValue::InternalLinkage); 576f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org} 586f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 596f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org// Helper routine 606f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org// FIXME : Take advantage of GlobalPrefix from AsmPrinter 616f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.orgstatic const char *addUnderscore(const char *name) { 626f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org size_t namelen = strlen(name); 636f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org char *symName = (char*)malloc(namelen+2); 646f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org symName[0] = '_'; 656f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org strcpy(&symName[1], name); 666f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org return symName; 676f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org} 686f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 696f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org// Map LLVM LinkageType to LTO LinakgeType 706f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.orgstatic LTOLinkageTypes 716f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.orggetLTOLinkageType(GlobalValue *v) 726f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org{ 736f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org LTOLinkageTypes lt; 746f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org if (v->hasExternalLinkage()) 756f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org lt = LTOExternalLinkage; 766f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org else if (v->hasLinkOnceLinkage()) 776f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org lt = LTOLinkOnceLinkage; 786f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org else if (v->hasWeakLinkage()) 796f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org lt = LTOWeakLinkage; 806f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org else 816f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org // Otherwise it is internal linkage for link time optimizer 826f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org lt = LTOInternalLinkage; 836f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org return lt; 846f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org} 856f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 866f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org// Find exeternal symbols referenced by VALUE. This is a recursive function. 876f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.orgstatic void 886f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.orgfindExternalRefs(Value *value, std::set<std::string> &references, 896f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org Mangler &mangler) { 906f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 916f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org if (GlobalValue *gv = dyn_cast<GlobalValue>(value)) { 926f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org LTOLinkageTypes lt = getLTOLinkageType(gv); 936f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org if (lt != LTOInternalLinkage && strncmp (gv->getName().c_str(), "llvm.", 5)) 946f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org references.insert(mangler.getValueName(gv)); 956f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org } 966f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org else if (Constant *c = dyn_cast<Constant>(value)) 976f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org // Handle ConstantExpr, ConstantStruct, ConstantArry etc.. 986f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org for (unsigned i = 0, e = c->getNumOperands(); i != e; ++i) 996f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org findExternalRefs(c->getOperand(i), references, mangler); 1006f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org} 1016f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 1026f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org/// InputFilename is a LLVM bytecode file. Read it using bytecode reader. 1036f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org/// Collect global functions and symbol names in symbols vector. 1046f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org/// Collect external references in references vector. 1056f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org/// Return LTO_READ_SUCCESS if there is no error. 1066f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.orgenum LTOStatus 1076f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.orgLinkTimeOptimizer::readLLVMObjectFile(const std::string &InputFilename, 1086f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org NameToSymbolMap &symbols, 1096f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org std::set<std::string> &references) 1106f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org{ 1116f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org Module *m = ParseBytecodeFile(InputFilename); 1126f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org if (!m) 1136f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org return LTO_READ_FAILURE; 1146f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 1156f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org // Use mangler to add GlobalPrefix to names to match linker names. 1166f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org // FIXME : Instead of hard coding "-" use GlobalPrefix. 1176f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org Mangler mangler(*m, "_"); 1186f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 1196f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org modules.push_back(m); 1206f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 1216f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org for (Module::iterator f = m->begin(), e = m->end(); f != e; ++f) { 1226f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 1236f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org LTOLinkageTypes lt = getLTOLinkageType(f); 1246f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 1256f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org if (!f->isExternal() && lt != LTOInternalLinkage 1266f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org && strncmp (f->getName().c_str(), "llvm.", 5)) { 1276f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org LLVMSymbol *newSymbol = new LLVMSymbol(lt, f, f->getName(), 1286f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org mangler.getValueName(f)); 1296f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org symbols[newSymbol->getMangledName()] = newSymbol; 1306f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org allSymbols[newSymbol->getMangledName()] = newSymbol; 1316f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org } 1326f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 1336f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org // Collect external symbols referenced by this function. 1346f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org for (Function::iterator b = f->begin(), fe = f->end(); b != fe; ++b) 1356f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org for (BasicBlock::iterator i = b->begin(), be = b->end(); 1366f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org i != be; ++i) 1376f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org for (unsigned count = 0, total = i->getNumOperands(); 1386f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org count != total; ++count) 1396f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org findExternalRefs(i->getOperand(count), references, mangler); 1406f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org } 1416f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 1426f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org for (Module::global_iterator v = m->global_begin(), e = m->global_end(); 1436f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org v != e; ++v) { 1446f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org LTOLinkageTypes lt = getLTOLinkageType(v); 1456f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org if (!v->isExternal() && lt != LTOInternalLinkage 146a4ce5bf56788dbb4835a5ef6143384266bbff5f5jshin@chromium.org && strncmp (v->getName().c_str(), "llvm.", 5)) { 1476f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org LLVMSymbol *newSymbol = new LLVMSymbol(lt, v, v->getName(), 1486f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org mangler.getValueName(v)); 1496f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org symbols[newSymbol->getMangledName()] = newSymbol; 1506f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 1516f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org for (unsigned count = 0, total = v->getNumOperands(); 1526f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org count != total; ++count) 1536f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org findExternalRefs(v->getOperand(count), references, mangler); 1546f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 1556f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org } 1566f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org } 1576f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 1586f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org return LTO_READ_SUCCESS; 1596f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org} 1606f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org 1616f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org/// Optimize module M using various IPO passes. Use exportList to 1626f31ac30b9092fd02a8c97e5216cf53f3e4fae4jshin@chromium.org/// internalize selected symbols. Target platform is selected 163/// based on information available to module M. No new target 164/// features are selected. 165static enum LTOStatus lto_optimize(Module *M, std::ostream &Out, 166 std::vector<const char *> &exportList) 167{ 168 // Instantiate the pass manager to organize the passes. 169 PassManager Passes; 170 171 // Collect Target info 172 std::string Err; 173 const TargetMachineRegistry::Entry* March = 174 TargetMachineRegistry::getClosestStaticTargetForModule(*M, Err); 175 176 if (March == 0) 177 return LTO_NO_TARGET; 178 179 // Create target 180 std::string Features; 181 std::auto_ptr<TargetMachine> target(March->CtorFn(*M, Features)); 182 if (!target.get()) 183 return LTO_NO_TARGET; 184 185 TargetMachine &Target = *target.get(); 186 187 // Start off with a verification pass. 188 Passes.add(createVerifierPass()); 189 190 // Add an appropriate TargetData instance for this module... 191 Passes.add(new TargetData(*Target.getTargetData())); 192 193 // Often if the programmer does not specify proper prototypes for the 194 // functions they are calling, they end up calling a vararg version of the 195 // function that does not get a body filled in (the real function has typed 196 // arguments). This pass merges the two functions. 197 Passes.add(createFunctionResolvingPass()); 198 199 // Internalize symbols if export list is nonemty 200 if (!exportList.empty()) 201 Passes.add(createInternalizePass(exportList)); 202 203 // Now that we internalized some globals, see if we can hack on them! 204 Passes.add(createGlobalOptimizerPass()); 205 206 // Linking modules together can lead to duplicated global constants, only 207 // keep one copy of each constant... 208 Passes.add(createConstantMergePass()); 209 210 // If the -s command line option was specified, strip the symbols out of the 211 // resulting program to make it smaller. -s is a GLD option that we are 212 // supporting. 213 Passes.add(createStripSymbolsPass()); 214 215 // Propagate constants at call sites into the functions they call. 216 Passes.add(createIPConstantPropagationPass()); 217 218 // Remove unused arguments from functions... 219 Passes.add(createDeadArgEliminationPass()); 220 221 Passes.add(createFunctionInliningPass()); // Inline small functions 222 223 Passes.add(createPruneEHPass()); // Remove dead EH info 224 225 Passes.add(createGlobalDCEPass()); // Remove dead functions 226 227 // If we didn't decide to inline a function, check to see if we can 228 // transform it to pass arguments by value instead of by reference. 229 Passes.add(createArgumentPromotionPass()); 230 231 // The IPO passes may leave cruft around. Clean up after them. 232 Passes.add(createInstructionCombiningPass()); 233 234 Passes.add(createScalarReplAggregatesPass()); // Break up allocas 235 236 // Run a few AA driven optimizations here and now, to cleanup the code. 237 Passes.add(createGlobalsModRefPass()); // IP alias analysis 238 239 Passes.add(createLICMPass()); // Hoist loop invariants 240 Passes.add(createLoadValueNumberingPass()); // GVN for load instrs 241 Passes.add(createGCSEPass()); // Remove common subexprs 242 Passes.add(createDeadStoreEliminationPass()); // Nuke dead stores 243 244 // Cleanup and simplify the code after the scalar optimizations. 245 Passes.add(createInstructionCombiningPass()); 246 247 // Delete basic blocks, which optimization passes may have killed... 248 Passes.add(createCFGSimplificationPass()); 249 250 // Now that we have optimized the program, discard unreachable functions... 251 Passes.add(createGlobalDCEPass()); 252 253 // Make sure everything is still good. 254 Passes.add(createVerifierPass()); 255 256 Target.addPassesToEmitFile(Passes, Out, TargetMachine::AssemblyFile, true); 257 258 // Run our queue of passes all at once now, efficiently. 259 Passes.run(*M); 260 261 return LTO_OPT_SUCCESS; 262} 263 264///Link all modules together and optimize them using IPO. Generate 265/// native object file using OutputFilename 266/// Return appropriate LTOStatus. 267enum LTOStatus 268LinkTimeOptimizer::optimizeModules(const std::string &OutputFilename, 269 std::vector<const char *> &exportList) 270{ 271 if (modules.empty()) 272 return LTO_NO_WORK; 273 274 std::ios::openmode io_mode = 275 std::ios::out | std::ios::trunc | std::ios::binary; 276 std::string *errMsg = NULL; 277 Module *bigOne = modules[0]; 278 Linker theLinker("LinkTimeOptimizer", bigOne, false); 279 for (unsigned i = 1, e = modules.size(); i != e; ++i) 280 if (theLinker.LinkModules(bigOne, modules[i], errMsg)) 281 return LTO_MODULE_MERGE_FAILURE; 282 283#if 0 284 // Enable this when -save-temps is used 285 std::ofstream Out("big.bc", io_mode); 286 WriteBytecodeToFile(bigOne, Out, true); 287#endif 288 289 // Strip leading underscore because it was added to match names 290 // seen by linker. 291 for (unsigned i = 0, e = exportList.size(); i != e; ++i) { 292 const char *name = exportList[i]; 293 if (strlen(name) > 2 && name[0] == '_') 294 exportList[i] = &name[1]; 295 } 296 297 sys::Path tmpAsmFilePath("/tmp/"); 298 tmpAsmFilePath.createTemporaryFileOnDisk(); 299 sys::RemoveFileOnSignal(tmpAsmFilePath); 300 301 std::ofstream asmFile(tmpAsmFilePath.c_str(), io_mode); 302 if (!asmFile.is_open() || asmFile.bad()) { 303 if (tmpAsmFilePath.exists()) 304 tmpAsmFilePath.eraseFromDisk(); 305 return LTO_WRITE_FAILURE; 306 } 307 308 enum LTOStatus status = lto_optimize(bigOne, asmFile, exportList); 309 asmFile.close(); 310 if (status != LTO_OPT_SUCCESS) { 311 tmpAsmFilePath.eraseFromDisk(); 312 return status; 313 } 314 315 // Run GCC to assemble and link the program into native code. 316 // 317 // Note: 318 // We can't just assemble and link the file with the system assembler 319 // and linker because we don't know where to put the _start symbol. 320 // GCC mysteriously knows how to do it. 321 const sys::Path gcc = FindExecutable("gcc", "/"); 322 if (gcc.isEmpty()) { 323 tmpAsmFilePath.eraseFromDisk(); 324 return LTO_ASM_FAILURE; 325 } 326 327 std::vector<const char*> args; 328 args.push_back(gcc.c_str()); 329 args.push_back("-c"); 330 args.push_back("-x"); 331 args.push_back("assembler"); 332 args.push_back("-o"); 333 args.push_back(OutputFilename.c_str()); 334 args.push_back(tmpAsmFilePath.c_str()); 335 args.push_back(0); 336 337 int R1 = sys::Program::ExecuteAndWait(gcc, &args[0], 0, 0, 1); 338 339 tmpAsmFilePath.eraseFromDisk(); 340 341 return LTO_OPT_SUCCESS; 342} 343