1 //===-LTOCodeGenerator.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 "LTOCodeGenerator.h"
16 #include "LTOModule.h"
17 #include "llvm/Constants.h"
18 #include "llvm/DerivedTypes.h"
19 #include "llvm/Linker.h"
20 #include "llvm/LLVMContext.h"
21 #include "llvm/Module.h"
22 #include "llvm/PassManager.h"
23 #include "llvm/Analysis/Passes.h"
24 #include "llvm/Analysis/Verifier.h"
25 #include "llvm/Bitcode/ReaderWriter.h"
26 #include "llvm/Config/config.h"
27 #include "llvm/MC/MCAsmInfo.h"
28 #include "llvm/MC/MCContext.h"
29 #include "llvm/MC/SubtargetFeature.h"
30 #include "llvm/Target/Mangler.h"
31 #include "llvm/Target/TargetOptions.h"
32 #include "llvm/Target/TargetData.h"
33 #include "llvm/Target/TargetMachine.h"
34 #include "llvm/Target/TargetRegisterInfo.h"
35 #include "llvm/Transforms/IPO.h"
36 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
37 #include "llvm/Support/CommandLine.h"
38 #include "llvm/Support/ErrorHandling.h"
39 #include "llvm/Support/FormattedStream.h"
40 #include "llvm/Support/MemoryBuffer.h"
41 #include "llvm/Support/SystemUtils.h"
42 #include "llvm/Support/ToolOutputFile.h"
43 #include "llvm/Support/Host.h"
44 #include "llvm/Support/Program.h"
45 #include "llvm/Support/Signals.h"
46 #include "llvm/Support/TargetRegistry.h"
47 #include "llvm/Support/TargetSelect.h"
48 #include "llvm/Support/system_error.h"
49 #include "llvm/ADT/StringExtras.h"
50 #include "llvm/ADT/Triple.h"
56 static cl::opt<bool> DisableInline("disable-inlining",
57 cl::desc("Do not run the inliner pass"));
59 const char* LTOCodeGenerator::getVersionString() {
60 #ifdef LLVM_VERSION_INFO
61 return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
63 return PACKAGE_NAME " version " PACKAGE_VERSION;
67 LTOCodeGenerator::LTOCodeGenerator()
68 : _context(getGlobalContext()),
69 _linker("LinkTimeOptimizer", "ld-temp.o", _context), _target(NULL),
70 _emitDwarfDebugInfo(false), _scopeRestrictionsDone(false),
71 _codeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC),
72 _nativeObjectFile(NULL) {
73 InitializeAllTargets();
74 InitializeAllTargetMCs();
75 InitializeAllAsmPrinters();
78 LTOCodeGenerator::~LTOCodeGenerator() {
80 delete _nativeObjectFile;
82 for (std::vector<char*>::iterator I = _codegenOptions.begin(),
83 E = _codegenOptions.end(); I != E; ++I)
87 bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg) {
88 bool ret = _linker.LinkInModule(mod->getLLVVMModule(), &errMsg);
90 const std::vector<const char*> &undefs = mod->getAsmUndefinedRefs();
91 for (int i = 0, e = undefs.size(); i != e; ++i)
92 _asmUndefinedRefs[undefs[i]] = 1;
97 bool LTOCodeGenerator::setDebugInfo(lto_debug_model debug,
98 std::string& errMsg) {
100 case LTO_DEBUG_MODEL_NONE:
101 _emitDwarfDebugInfo = false;
104 case LTO_DEBUG_MODEL_DWARF:
105 _emitDwarfDebugInfo = true;
108 llvm_unreachable("Unknown debug format!");
111 bool LTOCodeGenerator::setCodePICModel(lto_codegen_model model,
112 std::string& errMsg) {
114 case LTO_CODEGEN_PIC_MODEL_STATIC:
115 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
116 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
120 llvm_unreachable("Unknown PIC model!");
123 void LTOCodeGenerator::setCpu(const char* mCpu) {
127 void LTOCodeGenerator::addMustPreserveSymbol(const char* sym) {
128 _mustPreserveSymbols[sym] = 1;
131 bool LTOCodeGenerator::writeMergedModules(const char *path,
132 std::string &errMsg) {
133 if (determineTarget(errMsg))
136 // mark which symbols can not be internalized
137 applyScopeRestrictions();
139 // create output file
141 tool_output_file Out(path, ErrInfo,
142 raw_fd_ostream::F_Binary);
143 if (!ErrInfo.empty()) {
144 errMsg = "could not open bitcode file for writing: ";
149 // write bitcode to it
150 WriteBitcodeToFile(_linker.getModule(), Out.os());
153 if (Out.os().has_error()) {
154 errMsg = "could not write bitcode file: ";
156 Out.os().clear_error();
164 bool LTOCodeGenerator::compile_to_file(const char** name, std::string& errMsg) {
165 // make unique temp .o file to put generated object file
166 sys::PathWithStatus uniqueObjPath("lto-llvm.o");
167 if ( uniqueObjPath.createTemporaryFileOnDisk(false, &errMsg) ) {
168 uniqueObjPath.eraseFromDisk();
171 sys::RemoveFileOnSignal(uniqueObjPath);
173 // generate object file
174 bool genResult = false;
175 tool_output_file objFile(uniqueObjPath.c_str(), errMsg);
179 genResult = this->generateObjectFile(objFile.os(), errMsg);
180 objFile.os().close();
181 if (objFile.os().has_error()) {
182 objFile.os().clear_error();
188 uniqueObjPath.eraseFromDisk();
192 _nativeObjectPath = uniqueObjPath.str();
193 *name = _nativeObjectPath.c_str();
197 const void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg) {
199 if (compile_to_file(&name, errMsg))
202 // remove old buffer if compile() called twice
203 delete _nativeObjectFile;
205 // read .o file into memory buffer
206 OwningPtr<MemoryBuffer> BuffPtr;
207 if (error_code ec = MemoryBuffer::getFile(name, BuffPtr, -1, false)) {
208 errMsg = ec.message();
211 _nativeObjectFile = BuffPtr.take();
214 sys::Path(_nativeObjectPath).eraseFromDisk();
216 // return buffer, unless error
217 if ( _nativeObjectFile == NULL )
219 *length = _nativeObjectFile->getBufferSize();
220 return _nativeObjectFile->getBufferStart();
223 bool LTOCodeGenerator::determineTarget(std::string& errMsg) {
224 if ( _target == NULL ) {
225 std::string Triple = _linker.getModule()->getTargetTriple();
227 Triple = sys::getDefaultTargetTriple();
229 // create target machine from info for merged modules
230 const Target *march = TargetRegistry::lookupTarget(Triple, errMsg);
234 // The relocation model is actually a static member of TargetMachine and
235 // needs to be set before the TargetMachine is instantiated.
236 Reloc::Model RelocModel = Reloc::Default;
237 switch( _codeModel ) {
238 case LTO_CODEGEN_PIC_MODEL_STATIC:
239 RelocModel = Reloc::Static;
241 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
242 RelocModel = Reloc::PIC_;
244 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
245 RelocModel = Reloc::DynamicNoPIC;
249 // construct LTOModule, hand over ownership of module and target
250 SubtargetFeatures Features;
251 Features.getDefaultSubtargetFeatures(llvm::Triple(Triple));
252 std::string FeatureStr = Features.getString();
253 TargetOptions Options;
254 _target = march->createTargetMachine(Triple, _mCpu, FeatureStr, Options,
260 void LTOCodeGenerator::
261 applyRestriction(GlobalValue &GV,
262 std::vector<const char*> &mustPreserveList,
263 SmallPtrSet<GlobalValue*, 8> &asmUsed,
265 SmallString<64> Buffer;
266 mangler.getNameWithPrefix(Buffer, &GV, false);
268 if (GV.isDeclaration())
270 if (_mustPreserveSymbols.count(Buffer))
271 mustPreserveList.push_back(GV.getName().data());
272 if (_asmUndefinedRefs.count(Buffer))
276 static void findUsedValues(GlobalVariable *LLVMUsed,
277 SmallPtrSet<GlobalValue*, 8> &UsedValues) {
278 if (LLVMUsed == 0) return;
280 ConstantArray *Inits = dyn_cast<ConstantArray>(LLVMUsed->getInitializer());
281 if (Inits == 0) return;
283 for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
284 if (GlobalValue *GV =
285 dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
286 UsedValues.insert(GV);
289 void LTOCodeGenerator::applyScopeRestrictions() {
290 if (_scopeRestrictionsDone) return;
291 Module *mergedModule = _linker.getModule();
293 // Start off with a verification pass.
295 passes.add(createVerifierPass());
297 // mark which symbols can not be internalized
298 MCContext Context(*_target->getMCAsmInfo(), *_target->getRegisterInfo(),NULL);
299 Mangler mangler(Context, *_target->getTargetData());
300 std::vector<const char*> mustPreserveList;
301 SmallPtrSet<GlobalValue*, 8> asmUsed;
303 for (Module::iterator f = mergedModule->begin(),
304 e = mergedModule->end(); f != e; ++f)
305 applyRestriction(*f, mustPreserveList, asmUsed, mangler);
306 for (Module::global_iterator v = mergedModule->global_begin(),
307 e = mergedModule->global_end(); v != e; ++v)
308 applyRestriction(*v, mustPreserveList, asmUsed, mangler);
309 for (Module::alias_iterator a = mergedModule->alias_begin(),
310 e = mergedModule->alias_end(); a != e; ++a)
311 applyRestriction(*a, mustPreserveList, asmUsed, mangler);
313 GlobalVariable *LLVMCompilerUsed =
314 mergedModule->getGlobalVariable("llvm.compiler.used");
315 findUsedValues(LLVMCompilerUsed, asmUsed);
316 if (LLVMCompilerUsed)
317 LLVMCompilerUsed->eraseFromParent();
319 llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(_context);
320 std::vector<Constant*> asmUsed2;
321 for (SmallPtrSet<GlobalValue*, 16>::const_iterator i = asmUsed.begin(),
322 e = asmUsed.end(); i !=e; ++i) {
323 GlobalValue *GV = *i;
324 Constant *c = ConstantExpr::getBitCast(GV, i8PTy);
325 asmUsed2.push_back(c);
328 llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, asmUsed2.size());
330 new llvm::GlobalVariable(*mergedModule, ATy, false,
331 llvm::GlobalValue::AppendingLinkage,
332 llvm::ConstantArray::get(ATy, asmUsed2),
333 "llvm.compiler.used");
335 LLVMCompilerUsed->setSection("llvm.metadata");
337 passes.add(createInternalizePass(mustPreserveList));
339 // apply scope restrictions
340 passes.run(*mergedModule);
342 _scopeRestrictionsDone = true;
345 /// Optimize merged modules using various IPO passes
346 bool LTOCodeGenerator::generateObjectFile(raw_ostream &out,
347 std::string &errMsg) {
348 if ( this->determineTarget(errMsg) )
351 // mark which symbols can not be internalized
352 this->applyScopeRestrictions();
354 Module* mergedModule = _linker.getModule();
356 // if options were requested, set them
357 if ( !_codegenOptions.empty() )
358 cl::ParseCommandLineOptions(_codegenOptions.size(),
359 const_cast<char **>(&_codegenOptions[0]));
361 // Instantiate the pass manager to organize the passes.
364 // Start off with a verification pass.
365 passes.add(createVerifierPass());
367 // Add an appropriate TargetData instance for this module...
368 passes.add(new TargetData(*_target->getTargetData()));
370 PassManagerBuilder().populateLTOPassManager(passes, /*Internalize=*/ false,
373 // Make sure everything is still good.
374 passes.add(createVerifierPass());
376 FunctionPassManager *codeGenPasses = new FunctionPassManager(mergedModule);
378 codeGenPasses->add(new TargetData(*_target->getTargetData()));
380 formatted_raw_ostream Out(out);
382 if (_target->addPassesToEmitFile(*codeGenPasses, Out,
383 TargetMachine::CGFT_ObjectFile,
384 CodeGenOpt::Aggressive)) {
385 errMsg = "target file type not supported";
389 // Run our queue of passes all at once now, efficiently.
390 passes.run(*mergedModule);
392 // Run the code generator, and write assembly file
393 codeGenPasses->doInitialization();
395 for (Module::iterator
396 it = mergedModule->begin(), e = mergedModule->end(); it != e; ++it)
397 if (!it->isDeclaration())
398 codeGenPasses->run(*it);
400 codeGenPasses->doFinalization();
401 delete codeGenPasses;
403 return false; // success
406 /// setCodeGenDebugOptions - Set codegen debugging options to aid in debugging
408 void LTOCodeGenerator::setCodeGenDebugOptions(const char *options) {
409 for (std::pair<StringRef, StringRef> o = getToken(options);
410 !o.first.empty(); o = getToken(o.second)) {
411 // ParseCommandLineOptions() expects argv[0] to be program name. Lazily add
413 if ( _codegenOptions.empty() )
414 _codegenOptions.push_back(strdup("libLTO"));
415 _codegenOptions.push_back(strdup(o.first.str().c_str()));