1 //===-lto.cpp - LLVM Link Time Optimizer ----------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the Link Time Optimization library. This library is
11 // intended to be used by linker to optimize code at link time.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Module.h"
16 #include "llvm/PassManager.h"
17 #include "llvm/Linker.h"
18 #include "llvm/Constants.h"
19 #include "llvm/DerivedTypes.h"
20 #include "llvm/ModuleProvider.h"
21 #include "llvm/Bitcode/ReaderWriter.h"
22 #include "llvm/Support/CommandLine.h"
23 #include "llvm/Support/FileUtilities.h"
24 #include "llvm/Support/SystemUtils.h"
25 #include "llvm/Support/Mangler.h"
26 #include "llvm/Support/MemoryBuffer.h"
27 #include "llvm/System/Program.h"
28 #include "llvm/System/Signals.h"
29 #include "llvm/Analysis/Passes.h"
30 #include "llvm/Analysis/LoopPass.h"
31 #include "llvm/Analysis/Verifier.h"
32 #include "llvm/CodeGen/FileWriters.h"
33 #include "llvm/Target/SubtargetFeature.h"
34 #include "llvm/Target/TargetOptions.h"
35 #include "llvm/Target/TargetData.h"
36 #include "llvm/Target/TargetMachine.h"
37 #include "llvm/Target/TargetMachineRegistry.h"
38 #include "llvm/Target/TargetAsmInfo.h"
39 #include "llvm/Transforms/IPO.h"
40 #include "llvm/Transforms/Scalar.h"
41 #include "llvm/Analysis/LoadValueNumbering.h"
42 #include "llvm/Support/MathExtras.h"
43 #include "llvm/LinkTimeOptimizer.h"
49 llvm::LinkTimeOptimizer *createLLVMOptimizer(unsigned VERSION)
51 // Linker records LLVM_LTO_VERSION based on llvm optimizer available
52 // during linker build. Match linker's recorded LTO VERSION number
53 // with installed llvm optimizer version. If these numbers do not match
54 // then linker may not be able to use llvm optimizer dynamically.
55 if (VERSION != LLVM_LTO_VERSION)
58 llvm::LTO *l = new llvm::LTO();
62 /// If symbol is not used then make it internal and let optimizer takes
64 void LLVMSymbol::mayBeNotUsed() {
65 gv->setLinkage(GlobalValue::InternalLinkage);
68 // Map LLVM LinkageType to LTO LinakgeType
69 static LTOLinkageTypes
70 getLTOLinkageType(GlobalValue *v)
73 if (v->hasExternalLinkage())
74 lt = LTOExternalLinkage;
75 else if (v->hasLinkOnceLinkage())
76 lt = LTOLinkOnceLinkage;
77 else if (v->hasWeakLinkage())
80 // Otherwise it is internal linkage for link time optimizer
81 lt = LTOInternalLinkage;
85 // MAP LLVM VisibilityType to LTO VisibilityType
86 static LTOVisibilityTypes
87 getLTOVisibilityType(GlobalValue *v)
89 LTOVisibilityTypes vis;
90 if (v->hasHiddenVisibility())
91 vis = LTOHiddenVisibility;
92 else if (v->hasProtectedVisibility())
93 vis = LTOProtectedVisibility;
95 vis = LTODefaultVisibility;
99 // Find exeternal symbols referenced by VALUE. This is a recursive function.
101 findExternalRefs(Value *value, std::set<std::string> &references,
104 if (GlobalValue *gv = dyn_cast<GlobalValue>(value)) {
105 LTOLinkageTypes lt = getLTOLinkageType(gv);
106 if (lt != LTOInternalLinkage && strncmp (gv->getName().c_str(), "llvm.", 5))
107 references.insert(mangler.getValueName(gv));
110 // GlobalValue, even with InternalLinkage type, may have operands with
111 // ExternalLinkage type. Do not ignore these operands.
112 if (Constant *c = dyn_cast<Constant>(value))
113 // Handle ConstantExpr, ConstantStruct, ConstantArry etc..
114 for (unsigned i = 0, e = c->getNumOperands(); i != e; ++i)
115 findExternalRefs(c->getOperand(i), references, mangler);
118 /// If Module with InputFilename is available then remove it from allModules
119 /// and call delete on it.
121 LTO::removeModule (const std::string &InputFilename)
123 NameToModuleMap::iterator pos = allModules.find(InputFilename.c_str());
124 if (pos == allModules.end())
127 Module *m = pos->second;
128 allModules.erase(pos);
132 /// InputFilename is a LLVM bitcode file. If Module with InputFilename is
133 /// available then return it. Otherwise parseInputFilename.
135 LTO::getModule(const std::string &InputFilename)
139 NameToModuleMap::iterator pos = allModules.find(InputFilename.c_str());
140 if (pos != allModules.end())
141 m = allModules[InputFilename.c_str()];
143 if (MemoryBuffer *Buffer
144 = MemoryBuffer::getFile(&InputFilename[0], InputFilename.size())) {
145 m = ParseBitcodeFile(Buffer);
148 allModules[InputFilename.c_str()] = m;
153 /// InputFilename is a LLVM bitcode file. Reade this bitcode file and
154 /// set corresponding target triplet string.
156 LTO::getTargetTriple(const std::string &InputFilename,
157 std::string &targetTriple)
159 Module *m = getModule(InputFilename);
161 targetTriple = m->getTargetTriple();
164 /// InputFilename is a LLVM bitcode file. Read it using bitcode reader.
165 /// Collect global functions and symbol names in symbols vector.
166 /// Collect external references in references vector.
167 /// Return LTO_READ_SUCCESS if there is no error.
169 LTO::readLLVMObjectFile(const std::string &InputFilename,
170 NameToSymbolMap &symbols,
171 std::set<std::string> &references)
173 Module *m = getModule(InputFilename);
175 return LTO_READ_FAILURE;
177 // Collect Target info
181 return LTO_READ_FAILURE;
183 // Use mangler to add GlobalPrefix to names to match linker names.
184 // FIXME : Instead of hard coding "-" use GlobalPrefix.
185 Mangler mangler(*m, Target->getTargetAsmInfo()->getGlobalPrefix());
186 modules.push_back(m);
188 for (Module::iterator f = m->begin(), e = m->end(); f != e; ++f) {
189 LTOLinkageTypes lt = getLTOLinkageType(f);
190 LTOVisibilityTypes vis = getLTOVisibilityType(f);
191 if (!f->isDeclaration() && lt != LTOInternalLinkage
192 && strncmp (f->getName().c_str(), "llvm.", 5)) {
193 int alignment = ( 16 > f->getAlignment() ? 16 : f->getAlignment());
194 LLVMSymbol *newSymbol = new LLVMSymbol(lt, vis, f, f->getName(),
195 mangler.getValueName(f),
197 symbols[newSymbol->getMangledName()] = newSymbol;
198 allSymbols[newSymbol->getMangledName()] = newSymbol;
201 // Collect external symbols referenced by this function.
202 for (Function::iterator b = f->begin(), fe = f->end(); b != fe; ++b)
203 for (BasicBlock::iterator i = b->begin(), be = b->end();
205 for (unsigned count = 0, total = i->getNumOperands();
206 count != total; ++count)
207 findExternalRefs(i->getOperand(count), references, mangler);
211 for (Module::global_iterator v = m->global_begin(), e = m->global_end();
213 LTOLinkageTypes lt = getLTOLinkageType(v);
214 LTOVisibilityTypes vis = getLTOVisibilityType(v);
215 if (!v->isDeclaration() && lt != LTOInternalLinkage
216 && strncmp (v->getName().c_str(), "llvm.", 5)) {
217 const TargetData *TD = Target->getTargetData();
218 LLVMSymbol *newSymbol = new LLVMSymbol(lt, vis, v, v->getName(),
219 mangler.getValueName(v),
220 TD->getPreferredAlignmentLog(v));
221 symbols[newSymbol->getMangledName()] = newSymbol;
222 allSymbols[newSymbol->getMangledName()] = newSymbol;
224 for (unsigned count = 0, total = v->getNumOperands();
225 count != total; ++count)
226 findExternalRefs(v->getOperand(count), references, mangler);
231 return LTO_READ_SUCCESS;
234 /// Get TargetMachine.
235 /// Use module M to find appropriate Target.
237 LTO::getTarget (Module *M) {
243 const TargetMachineRegistry::entry* March =
244 TargetMachineRegistry::getClosestStaticTargetForModule(*M, Err);
250 SubtargetFeatures Features;
251 std::string FeatureStr;
252 std::string TargetTriple = M->getTargetTriple();
254 if (strncmp(TargetTriple.c_str(), "powerpc-apple-", 14) == 0)
255 Features.AddFeature("altivec", true);
256 else if (strncmp(TargetTriple.c_str(), "powerpc64-apple-", 16) == 0) {
257 Features.AddFeature("64bit", true);
258 Features.AddFeature("altivec", true);
261 FeatureStr = Features.getString();
262 Target = March->CtorFn(*M, FeatureStr);
265 /// Optimize module M using various IPO passes. Use exportList to
266 /// internalize selected symbols. Target platform is selected
267 /// based on information available to module M. No new target
268 /// features are selected.
270 LTO::optimize(Module *M, std::ostream &Out,
271 std::vector<const char *> &exportList)
273 // Instantiate the pass manager to organize the passes.
276 // Collect Target info
280 return LTO_NO_TARGET;
282 // If target supports exception handling then enable it now.
283 if (Target->getTargetAsmInfo()->doesSupportExceptionHandling())
284 ExceptionHandling = true;
286 // Start off with a verification pass.
287 Passes.add(createVerifierPass());
289 // Add an appropriate TargetData instance for this module...
290 Passes.add(new TargetData(*Target->getTargetData()));
292 // Internalize symbols if export list is nonemty
293 if (!exportList.empty())
294 Passes.add(createInternalizePass(exportList));
296 // Now that we internalized some globals, see if we can hack on them!
297 Passes.add(createGlobalOptimizerPass());
299 // Linking modules together can lead to duplicated global constants, only
300 // keep one copy of each constant...
301 Passes.add(createConstantMergePass());
303 // If the -s command line option was specified, strip the symbols out of the
304 // resulting program to make it smaller. -s is a GLD option that we are
306 Passes.add(createStripSymbolsPass());
308 // Propagate constants at call sites into the functions they call.
309 Passes.add(createIPConstantPropagationPass());
311 // Remove unused arguments from functions...
312 Passes.add(createDeadArgEliminationPass());
314 Passes.add(createFunctionInliningPass()); // Inline small functions
316 Passes.add(createPruneEHPass()); // Remove dead EH info
318 Passes.add(createGlobalDCEPass()); // Remove dead functions
320 // If we didn't decide to inline a function, check to see if we can
321 // transform it to pass arguments by value instead of by reference.
322 Passes.add(createArgumentPromotionPass());
324 // The IPO passes may leave cruft around. Clean up after them.
325 Passes.add(createInstructionCombiningPass());
327 Passes.add(createScalarReplAggregatesPass()); // Break up allocas
329 // Run a few AA driven optimizations here and now, to cleanup the code.
330 Passes.add(createGlobalsModRefPass()); // IP alias analysis
332 Passes.add(createLICMPass()); // Hoist loop invariants
333 Passes.add(createGVNPass()); // Remove common subexprs
334 Passed.add(createMemCpyOptPass()); // Remove dead memcpy's
335 Passes.add(createDeadStoreEliminationPass()); // Nuke dead stores
337 // Cleanup and simplify the code after the scalar optimizations.
338 Passes.add(createInstructionCombiningPass());
340 // Delete basic blocks, which optimization passes may have killed...
341 Passes.add(createCFGSimplificationPass());
343 // Now that we have optimized the program, discard unreachable functions...
344 Passes.add(createGlobalDCEPass());
346 // Make sure everything is still good.
347 Passes.add(createVerifierPass());
349 FunctionPassManager *CodeGenPasses =
350 new FunctionPassManager(new ExistingModuleProvider(M));
352 CodeGenPasses->add(new TargetData(*Target->getTargetData()));
354 MachineCodeEmitter *MCE = 0;
356 switch (Target->addPassesToEmitFile(*CodeGenPasses, Out,
357 TargetMachine::AssemblyFile, true)) {
359 case FileModel::Error:
360 return LTO_WRITE_FAILURE;
361 case FileModel::AsmFile:
363 case FileModel::MachOFile:
364 MCE = AddMachOWriter(*CodeGenPasses, Out, *Target);
366 case FileModel::ElfFile:
367 MCE = AddELFWriter(*CodeGenPasses, Out, *Target);
371 if (Target->addPassesToEmitFileFinish(*CodeGenPasses, MCE, true))
372 return LTO_WRITE_FAILURE;
374 // Run our queue of passes all at once now, efficiently.
377 // Run the code generator, if present.
378 CodeGenPasses->doInitialization();
379 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I) {
380 if (!I->isDeclaration())
381 CodeGenPasses->run(*I);
383 CodeGenPasses->doFinalization();
385 return LTO_OPT_SUCCESS;
388 ///Link all modules together and optimize them using IPO. Generate
389 /// native object file using OutputFilename
390 /// Return appropriate LTOStatus.
392 LTO::optimizeModules(const std::string &OutputFilename,
393 std::vector<const char *> &exportList,
394 std::string &targetTriple,
395 bool saveTemps, const char *FinalOutputFilename)
400 std::ios::openmode io_mode =
401 std::ios::out | std::ios::trunc | std::ios::binary;
402 std::string *errMsg = NULL;
403 Module *bigOne = modules[0];
404 Linker theLinker("LinkTimeOptimizer", bigOne, false);
405 for (unsigned i = 1, e = modules.size(); i != e; ++i)
406 if (theLinker.LinkModules(bigOne, modules[i], errMsg))
407 return LTO_MODULE_MERGE_FAILURE;
408 // all modules have been handed off to the linker.
411 sys::Path FinalOutputPath(FinalOutputFilename);
412 FinalOutputPath.eraseSuffix();
415 case LTO_CGM_Dynamic:
416 Target->setRelocationModel(Reloc::PIC_);
418 case LTO_CGM_DynamicNoPIC:
419 Target->setRelocationModel(Reloc::DynamicNoPIC);
422 Target->setRelocationModel(Reloc::Static);
427 std::string tempFileName(FinalOutputPath.c_str());
428 tempFileName += "0.bc";
429 std::ofstream Out(tempFileName.c_str(), io_mode);
430 WriteBitcodeToFile(bigOne, Out);
433 // Strip leading underscore because it was added to match names
435 for (unsigned i = 0, e = exportList.size(); i != e; ++i) {
436 const char *name = exportList[i];
437 NameToSymbolMap::iterator itr = allSymbols.find(name);
438 if (itr != allSymbols.end())
439 exportList[i] = allSymbols[name]->getName();
444 sys::Path TempDir = sys::Path::GetTemporaryDirectory(&ErrMsg);
445 if (TempDir.isEmpty()) {
446 cerr << "lto: " << ErrMsg << "\n";
447 return LTO_WRITE_FAILURE;
449 sys::Path tmpAsmFilePath(TempDir);
450 if (!tmpAsmFilePath.appendComponent("lto")) {
451 cerr << "lto: " << ErrMsg << "\n";
452 TempDir.eraseFromDisk(true);
453 return LTO_WRITE_FAILURE;
455 if (tmpAsmFilePath.createTemporaryFileOnDisk(true, &ErrMsg)) {
456 cerr << "lto: " << ErrMsg << "\n";
457 TempDir.eraseFromDisk(true);
458 return LTO_WRITE_FAILURE;
460 sys::RemoveFileOnSignal(tmpAsmFilePath);
462 std::ofstream asmFile(tmpAsmFilePath.c_str(), io_mode);
463 if (!asmFile.is_open() || asmFile.bad()) {
464 if (tmpAsmFilePath.exists()) {
465 tmpAsmFilePath.eraseFromDisk();
466 TempDir.eraseFromDisk(true);
468 return LTO_WRITE_FAILURE;
471 enum LTOStatus status = optimize(bigOne, asmFile, exportList);
473 if (status != LTO_OPT_SUCCESS) {
474 tmpAsmFilePath.eraseFromDisk();
475 TempDir.eraseFromDisk(true);
480 std::string tempFileName(FinalOutputPath.c_str());
481 tempFileName += "1.bc";
482 std::ofstream Out(tempFileName.c_str(), io_mode);
483 WriteBitcodeToFile(bigOne, Out);
486 targetTriple = bigOne->getTargetTriple();
488 // Run GCC to assemble and link the program into native code.
491 // We can't just assemble and link the file with the system assembler
492 // and linker because we don't know where to put the _start symbol.
493 // GCC mysteriously knows how to do it.
494 const sys::Path gcc = sys::Program::FindProgramByName("gcc");
496 tmpAsmFilePath.eraseFromDisk();
497 TempDir.eraseFromDisk(true);
498 return LTO_ASM_FAILURE;
501 std::vector<const char*> args;
502 args.push_back(gcc.c_str());
503 if (strncmp(targetTriple.c_str(), "i686-apple-", 11) == 0) {
504 args.push_back("-arch");
505 args.push_back("i386");
507 if (strncmp(targetTriple.c_str(), "x86_64-apple-", 13) == 0) {
508 args.push_back("-arch");
509 args.push_back("x86_64");
511 if (strncmp(targetTriple.c_str(), "powerpc-apple-", 14) == 0) {
512 args.push_back("-arch");
513 args.push_back("ppc");
515 if (strncmp(targetTriple.c_str(), "powerpc64-apple-", 16) == 0) {
516 args.push_back("-arch");
517 args.push_back("ppc64");
519 args.push_back("-c");
520 args.push_back("-x");
521 args.push_back("assembler");
522 args.push_back("-o");
523 args.push_back(OutputFilename.c_str());
524 args.push_back(tmpAsmFilePath.c_str());
527 if (sys::Program::ExecuteAndWait(gcc, &args[0], 0, 0, 0, 0, &ErrMsg)) {
528 cerr << "lto: " << ErrMsg << "\n";
529 return LTO_ASM_FAILURE;
532 tmpAsmFilePath.eraseFromDisk();
533 TempDir.eraseFromDisk(true);
535 return LTO_OPT_SUCCESS;
538 void LTO::printVersion() {
539 cl::PrintVersionMessage();
542 /// Unused pure-virtual destructor. Must remain empty.
543 LinkTimeOptimizer::~LinkTimeOptimizer() {}
545 /// Destruct LTO. Delete all modules, symbols and target.
548 for (std::vector<Module *>::iterator itr = modules.begin(), e = modules.end();
554 for (NameToSymbolMap::iterator itr = allSymbols.begin(), e = allSymbols.end();