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/ADT/StringExtras.h"
18 #include "llvm/Analysis/Passes.h"
19 #include "llvm/Analysis/Verifier.h"
20 #include "llvm/Bitcode/ReaderWriter.h"
21 #include "llvm/Config/config.h"
22 #include "llvm/IR/Constants.h"
23 #include "llvm/IR/DataLayout.h"
24 #include "llvm/IR/DerivedTypes.h"
25 #include "llvm/IR/LLVMContext.h"
26 #include "llvm/IR/Module.h"
27 #include "llvm/Linker.h"
28 #include "llvm/MC/MCAsmInfo.h"
29 #include "llvm/MC/MCContext.h"
30 #include "llvm/MC/SubtargetFeature.h"
31 #include "llvm/PassManager.h"
32 #include "llvm/Support/CommandLine.h"
33 #include "llvm/Support/FormattedStream.h"
34 #include "llvm/Support/Host.h"
35 #include "llvm/Support/MemoryBuffer.h"
36 #include "llvm/Support/Signals.h"
37 #include "llvm/Support/TargetRegistry.h"
38 #include "llvm/Support/TargetSelect.h"
39 #include "llvm/Support/ToolOutputFile.h"
40 #include "llvm/Support/system_error.h"
41 #include "llvm/Target/Mangler.h"
42 #include "llvm/Target/TargetMachine.h"
43 #include "llvm/Target/TargetOptions.h"
44 #include "llvm/Target/TargetRegisterInfo.h"
45 #include "llvm/Transforms/IPO.h"
46 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
50 DisableInline("disable-inlining", cl::init(false),
51 cl::desc("Do not run the inliner pass"));
54 DisableGVNLoadPRE("disable-gvn-loadpre", cl::init(false),
55 cl::desc("Do not run the GVN load PRE pass"));
57 const char* LTOCodeGenerator::getVersionString() {
58 #ifdef LLVM_VERSION_INFO
59 return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
61 return PACKAGE_NAME " version " PACKAGE_VERSION;
65 LTOCodeGenerator::LTOCodeGenerator()
66 : _context(getGlobalContext()),
67 _linker("LinkTimeOptimizer", "ld-temp.o", _context), _target(NULL),
68 _emitDwarfDebugInfo(false), _scopeRestrictionsDone(false),
69 _codeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC),
70 _nativeObjectFile(NULL) {
71 InitializeAllTargets();
72 InitializeAllTargetMCs();
73 InitializeAllAsmPrinters();
76 LTOCodeGenerator::~LTOCodeGenerator() {
78 delete _nativeObjectFile;
80 for (std::vector<char*>::iterator I = _codegenOptions.begin(),
81 E = _codegenOptions.end(); I != E; ++I)
85 bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg) {
86 bool ret = _linker.LinkInModule(mod->getLLVVMModule(), &errMsg);
88 const std::vector<const char*> &undefs = mod->getAsmUndefinedRefs();
89 for (int i = 0, e = undefs.size(); i != e; ++i)
90 _asmUndefinedRefs[undefs[i]] = 1;
95 bool LTOCodeGenerator::setDebugInfo(lto_debug_model debug,
96 std::string& errMsg) {
98 case LTO_DEBUG_MODEL_NONE:
99 _emitDwarfDebugInfo = false;
102 case LTO_DEBUG_MODEL_DWARF:
103 _emitDwarfDebugInfo = true;
106 llvm_unreachable("Unknown debug format!");
109 bool LTOCodeGenerator::setCodePICModel(lto_codegen_model model,
110 std::string& errMsg) {
112 case LTO_CODEGEN_PIC_MODEL_STATIC:
113 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
114 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
118 llvm_unreachable("Unknown PIC model!");
121 bool LTOCodeGenerator::writeMergedModules(const char *path,
122 std::string &errMsg) {
123 if (determineTarget(errMsg))
126 // mark which symbols can not be internalized
127 applyScopeRestrictions();
129 // create output file
131 tool_output_file Out(path, ErrInfo,
132 raw_fd_ostream::F_Binary);
133 if (!ErrInfo.empty()) {
134 errMsg = "could not open bitcode file for writing: ";
139 // write bitcode to it
140 WriteBitcodeToFile(_linker.getModule(), Out.os());
143 if (Out.os().has_error()) {
144 errMsg = "could not write bitcode file: ";
146 Out.os().clear_error();
154 bool LTOCodeGenerator::compile_to_file(const char** name, std::string& errMsg) {
155 // make unique temp .o file to put generated object file
156 sys::PathWithStatus uniqueObjPath("lto-llvm.o");
157 if (uniqueObjPath.createTemporaryFileOnDisk(false, &errMsg)) {
158 uniqueObjPath.eraseFromDisk();
161 sys::RemoveFileOnSignal(uniqueObjPath);
163 // generate object file
164 bool genResult = false;
165 tool_output_file objFile(uniqueObjPath.c_str(), errMsg);
166 if (!errMsg.empty()) {
167 uniqueObjPath.eraseFromDisk();
171 genResult = this->generateObjectFile(objFile.os(), errMsg);
172 objFile.os().close();
173 if (objFile.os().has_error()) {
174 objFile.os().clear_error();
175 uniqueObjPath.eraseFromDisk();
181 uniqueObjPath.eraseFromDisk();
185 _nativeObjectPath = uniqueObjPath.str();
186 *name = _nativeObjectPath.c_str();
190 const void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg) {
192 if (compile_to_file(&name, errMsg))
195 // remove old buffer if compile() called twice
196 delete _nativeObjectFile;
198 // read .o file into memory buffer
199 OwningPtr<MemoryBuffer> BuffPtr;
200 if (error_code ec = MemoryBuffer::getFile(name, BuffPtr, -1, false)) {
201 errMsg = ec.message();
202 sys::Path(_nativeObjectPath).eraseFromDisk();
205 _nativeObjectFile = BuffPtr.take();
208 sys::Path(_nativeObjectPath).eraseFromDisk();
210 // return buffer, unless error
211 if (_nativeObjectFile == NULL)
213 *length = _nativeObjectFile->getBufferSize();
214 return _nativeObjectFile->getBufferStart();
217 bool LTOCodeGenerator::determineTarget(std::string& errMsg) {
221 std::string TripleStr = _linker.getModule()->getTargetTriple();
222 if (TripleStr.empty())
223 TripleStr = sys::getDefaultTargetTriple();
224 llvm::Triple Triple(TripleStr);
226 // create target machine from info for merged modules
227 const Target *march = TargetRegistry::lookupTarget(TripleStr, errMsg);
231 // The relocation model is actually a static member of TargetMachine and
232 // needs to be set before the TargetMachine is instantiated.
233 Reloc::Model RelocModel = Reloc::Default;
234 switch (_codeModel) {
235 case LTO_CODEGEN_PIC_MODEL_STATIC:
236 RelocModel = Reloc::Static;
238 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
239 RelocModel = Reloc::PIC_;
241 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
242 RelocModel = Reloc::DynamicNoPIC;
246 // construct LTOModule, hand over ownership of module and target
247 SubtargetFeatures Features;
248 Features.getDefaultSubtargetFeatures(Triple);
249 std::string FeatureStr = Features.getString();
250 // Set a default CPU for Darwin triples.
251 if (_mCpu.empty() && Triple.isOSDarwin()) {
252 if (Triple.getArch() == llvm::Triple::x86_64)
254 else if (Triple.getArch() == llvm::Triple::x86)
257 TargetOptions Options;
258 LTOModule::getTargetOptions(Options);
259 _target = march->createTargetMachine(TripleStr, _mCpu, FeatureStr, Options,
260 RelocModel, CodeModel::Default,
261 CodeGenOpt::Aggressive);
265 void LTOCodeGenerator::
266 applyRestriction(GlobalValue &GV,
267 std::vector<const char*> &mustPreserveList,
268 SmallPtrSet<GlobalValue*, 8> &asmUsed,
270 SmallString<64> Buffer;
271 mangler.getNameWithPrefix(Buffer, &GV, false);
273 if (GV.isDeclaration())
275 if (_mustPreserveSymbols.count(Buffer))
276 mustPreserveList.push_back(GV.getName().data());
277 if (_asmUndefinedRefs.count(Buffer))
281 static void findUsedValues(GlobalVariable *LLVMUsed,
282 SmallPtrSet<GlobalValue*, 8> &UsedValues) {
283 if (LLVMUsed == 0) return;
285 ConstantArray *Inits = dyn_cast<ConstantArray>(LLVMUsed->getInitializer());
286 if (Inits == 0) return;
288 for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
289 if (GlobalValue *GV =
290 dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
291 UsedValues.insert(GV);
294 void LTOCodeGenerator::applyScopeRestrictions() {
295 if (_scopeRestrictionsDone) return;
296 Module *mergedModule = _linker.getModule();
298 // Start off with a verification pass.
300 passes.add(createVerifierPass());
302 // mark which symbols can not be internalized
303 MCContext Context(*_target->getMCAsmInfo(), *_target->getRegisterInfo(),NULL);
304 Mangler mangler(Context, *_target->getDataLayout());
305 std::vector<const char*> mustPreserveList;
306 SmallPtrSet<GlobalValue*, 8> asmUsed;
308 for (Module::iterator f = mergedModule->begin(),
309 e = mergedModule->end(); f != e; ++f)
310 applyRestriction(*f, mustPreserveList, asmUsed, mangler);
311 for (Module::global_iterator v = mergedModule->global_begin(),
312 e = mergedModule->global_end(); v != e; ++v)
313 applyRestriction(*v, mustPreserveList, asmUsed, mangler);
314 for (Module::alias_iterator a = mergedModule->alias_begin(),
315 e = mergedModule->alias_end(); a != e; ++a)
316 applyRestriction(*a, mustPreserveList, asmUsed, mangler);
318 GlobalVariable *LLVMCompilerUsed =
319 mergedModule->getGlobalVariable("llvm.compiler.used");
320 findUsedValues(LLVMCompilerUsed, asmUsed);
321 if (LLVMCompilerUsed)
322 LLVMCompilerUsed->eraseFromParent();
324 llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(_context);
325 std::vector<Constant*> asmUsed2;
326 for (SmallPtrSet<GlobalValue*, 16>::const_iterator i = asmUsed.begin(),
327 e = asmUsed.end(); i !=e; ++i) {
328 GlobalValue *GV = *i;
329 Constant *c = ConstantExpr::getBitCast(GV, i8PTy);
330 asmUsed2.push_back(c);
333 llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, asmUsed2.size());
335 new llvm::GlobalVariable(*mergedModule, ATy, false,
336 llvm::GlobalValue::AppendingLinkage,
337 llvm::ConstantArray::get(ATy, asmUsed2),
338 "llvm.compiler.used");
340 LLVMCompilerUsed->setSection("llvm.metadata");
342 passes.add(createInternalizePass(mustPreserveList));
344 // apply scope restrictions
345 passes.run(*mergedModule);
347 _scopeRestrictionsDone = true;
350 /// Optimize merged modules using various IPO passes
351 bool LTOCodeGenerator::generateObjectFile(raw_ostream &out,
352 std::string &errMsg) {
353 if (this->determineTarget(errMsg))
356 Module* mergedModule = _linker.getModule();
358 // if options were requested, set them
359 if (!_codegenOptions.empty())
360 cl::ParseCommandLineOptions(_codegenOptions.size(),
361 const_cast<char **>(&_codegenOptions[0]));
363 // mark which symbols can not be internalized
364 this->applyScopeRestrictions();
366 // Instantiate the pass manager to organize the passes.
369 // Start off with a verification pass.
370 passes.add(createVerifierPass());
372 // Add an appropriate DataLayout instance for this module...
373 passes.add(new DataLayout(*_target->getDataLayout()));
374 _target->addAnalysisPasses(passes);
376 // Enabling internalize here would use its AllButMain variant. It
377 // keeps only main if it exists and does nothing for libraries. Instead
378 // we create the pass ourselves with the symbol list provided by the linker.
379 PassManagerBuilder().populateLTOPassManager(passes,
380 /*Internalize=*/false,
384 // Make sure everything is still good.
385 passes.add(createVerifierPass());
387 FunctionPassManager *codeGenPasses = new FunctionPassManager(mergedModule);
389 codeGenPasses->add(new DataLayout(*_target->getDataLayout()));
390 _target->addAnalysisPasses(*codeGenPasses);
392 formatted_raw_ostream Out(out);
394 if (_target->addPassesToEmitFile(*codeGenPasses, Out,
395 TargetMachine::CGFT_ObjectFile)) {
396 errMsg = "target file type not supported";
400 // Run our queue of passes all at once now, efficiently.
401 passes.run(*mergedModule);
403 // Run the code generator, and write assembly file
404 codeGenPasses->doInitialization();
406 for (Module::iterator
407 it = mergedModule->begin(), e = mergedModule->end(); it != e; ++it)
408 if (!it->isDeclaration())
409 codeGenPasses->run(*it);
411 codeGenPasses->doFinalization();
412 delete codeGenPasses;
414 return false; // success
417 /// setCodeGenDebugOptions - Set codegen debugging options to aid in debugging
419 void LTOCodeGenerator::setCodeGenDebugOptions(const char *options) {
420 for (std::pair<StringRef, StringRef> o = getToken(options);
421 !o.first.empty(); o = getToken(o.second)) {
422 // ParseCommandLineOptions() expects argv[0] to be program name. Lazily add
424 if (_codegenOptions.empty())
425 _codegenOptions.push_back(strdup("libLTO"));
426 _codegenOptions.push_back(strdup(o.first.str().c_str()));