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/InitializePasses.h"
28 #include "llvm/Linker.h"
29 #include "llvm/MC/MCAsmInfo.h"
30 #include "llvm/MC/MCContext.h"
31 #include "llvm/MC/SubtargetFeature.h"
32 #include "llvm/PassManager.h"
33 #include "llvm/Support/CommandLine.h"
34 #include "llvm/Support/FileSystem.h"
35 #include "llvm/Support/FormattedStream.h"
36 #include "llvm/Support/Host.h"
37 #include "llvm/Support/MemoryBuffer.h"
38 #include "llvm/Support/Signals.h"
39 #include "llvm/Support/TargetRegistry.h"
40 #include "llvm/Support/TargetSelect.h"
41 #include "llvm/Support/ToolOutputFile.h"
42 #include "llvm/Support/system_error.h"
43 #include "llvm/Target/Mangler.h"
44 #include "llvm/Target/TargetMachine.h"
45 #include "llvm/Target/TargetOptions.h"
46 #include "llvm/Target/TargetRegisterInfo.h"
47 #include "llvm/Transforms/IPO.h"
48 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
49 #include "llvm/Transforms/ObjCARC.h"
53 DisableOpt("disable-opt", cl::init(false),
54 cl::desc("Do not run any optimization passes"));
57 DisableInline("disable-inlining", cl::init(false),
58 cl::desc("Do not run the inliner pass"));
61 DisableGVNLoadPRE("disable-gvn-loadpre", cl::init(false),
62 cl::desc("Do not run the GVN load PRE pass"));
64 const char* LTOCodeGenerator::getVersionString() {
65 #ifdef LLVM_VERSION_INFO
66 return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
68 return PACKAGE_NAME " version " PACKAGE_VERSION;
72 LTOCodeGenerator::LTOCodeGenerator()
73 : _context(getGlobalContext()),
74 _linker(new Module("ld-temp.o", _context)), _target(NULL),
75 _emitDwarfDebugInfo(false), _scopeRestrictionsDone(false),
76 _codeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC),
77 _nativeObjectFile(NULL) {
78 InitializeAllTargets();
79 InitializeAllTargetMCs();
80 InitializeAllAsmPrinters();
81 initializeLTOPasses();
84 LTOCodeGenerator::~LTOCodeGenerator() {
86 delete _nativeObjectFile;
87 delete _linker.getModule();
89 for (std::vector<char*>::iterator I = _codegenOptions.begin(),
90 E = _codegenOptions.end(); I != E; ++I)
94 // Initialize LTO passes. Please keep this funciton in sync with
95 // PassManagerBuilder::populateLTOPassManager(), and make sure all LTO
96 // passes are initialized.
98 void LTOCodeGenerator::initializeLTOPasses() {
99 PassRegistry &R = *PassRegistry::getPassRegistry();
101 initializeInternalizePassPass(R);
102 initializeIPSCCPPass(R);
103 initializeGlobalOptPass(R);
104 initializeConstantMergePass(R);
105 initializeDAHPass(R);
106 initializeInstCombinerPass(R);
107 initializeSimpleInlinerPass(R);
108 initializePruneEHPass(R);
109 initializeGlobalDCEPass(R);
110 initializeArgPromotionPass(R);
111 initializeJumpThreadingPass(R);
112 initializeSROAPass(R);
113 initializeSROA_DTPass(R);
114 initializeSROA_SSAUpPass(R);
115 initializeFunctionAttrsPass(R);
116 initializeGlobalsModRefPass(R);
117 initializeLICMPass(R);
118 initializeGVNPass(R);
119 initializeMemCpyOptPass(R);
120 initializeDCEPass(R);
121 initializeCFGSimplifyPassPass(R);
124 bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg) {
125 bool ret = _linker.linkInModule(mod->getLLVVMModule(), &errMsg);
127 const std::vector<const char*> &undefs = mod->getAsmUndefinedRefs();
128 for (int i = 0, e = undefs.size(); i != e; ++i)
129 _asmUndefinedRefs[undefs[i]] = 1;
134 bool LTOCodeGenerator::setDebugInfo(lto_debug_model debug,
135 std::string& errMsg) {
137 case LTO_DEBUG_MODEL_NONE:
138 _emitDwarfDebugInfo = false;
141 case LTO_DEBUG_MODEL_DWARF:
142 _emitDwarfDebugInfo = true;
145 llvm_unreachable("Unknown debug format!");
148 bool LTOCodeGenerator::setCodePICModel(lto_codegen_model model,
149 std::string& errMsg) {
151 case LTO_CODEGEN_PIC_MODEL_STATIC:
152 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
153 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
157 llvm_unreachable("Unknown PIC model!");
160 bool LTOCodeGenerator::writeMergedModules(const char *path,
161 std::string &errMsg) {
162 if (determineTarget(errMsg))
165 // Run the verifier on the merged modules.
167 passes.add(createVerifierPass());
168 passes.run(*_linker.getModule());
170 // create output file
172 tool_output_file Out(path, ErrInfo, sys::fs::F_Binary);
173 if (!ErrInfo.empty()) {
174 errMsg = "could not open bitcode file for writing: ";
179 // write bitcode to it
180 WriteBitcodeToFile(_linker.getModule(), Out.os());
183 if (Out.os().has_error()) {
184 errMsg = "could not write bitcode file: ";
186 Out.os().clear_error();
194 bool LTOCodeGenerator::compile_to_file(const char** name, std::string& errMsg) {
195 // make unique temp .o file to put generated object file
196 SmallString<128> Filename;
198 error_code EC = sys::fs::createTemporaryFile("lto-llvm", "o", FD, Filename);
200 errMsg = EC.message();
204 // generate object file
205 tool_output_file objFile(Filename.c_str(), FD);
207 bool genResult = generateObjectFile(objFile.os(), errMsg);
208 objFile.os().close();
209 if (objFile.os().has_error()) {
210 objFile.os().clear_error();
211 sys::fs::remove(Twine(Filename));
217 sys::fs::remove(Twine(Filename));
221 _nativeObjectPath = Filename.c_str();
222 *name = _nativeObjectPath.c_str();
226 const void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg) {
228 if (compile_to_file(&name, errMsg))
231 // remove old buffer if compile() called twice
232 delete _nativeObjectFile;
234 // read .o file into memory buffer
235 OwningPtr<MemoryBuffer> BuffPtr;
236 if (error_code ec = MemoryBuffer::getFile(name, BuffPtr, -1, false)) {
237 errMsg = ec.message();
238 sys::fs::remove(_nativeObjectPath);
241 _nativeObjectFile = BuffPtr.take();
244 sys::fs::remove(_nativeObjectPath);
246 // return buffer, unless error
247 if (_nativeObjectFile == NULL)
249 *length = _nativeObjectFile->getBufferSize();
250 return _nativeObjectFile->getBufferStart();
253 bool LTOCodeGenerator::determineTarget(std::string &errMsg) {
257 // if options were requested, set them
258 if (!_codegenOptions.empty())
259 cl::ParseCommandLineOptions(_codegenOptions.size(),
260 const_cast<char **>(&_codegenOptions[0]));
262 std::string TripleStr = _linker.getModule()->getTargetTriple();
263 if (TripleStr.empty())
264 TripleStr = sys::getDefaultTargetTriple();
265 llvm::Triple Triple(TripleStr);
267 // create target machine from info for merged modules
268 const Target *march = TargetRegistry::lookupTarget(TripleStr, errMsg);
272 // The relocation model is actually a static member of TargetMachine and
273 // needs to be set before the TargetMachine is instantiated.
274 Reloc::Model RelocModel = Reloc::Default;
275 switch (_codeModel) {
276 case LTO_CODEGEN_PIC_MODEL_STATIC:
277 RelocModel = Reloc::Static;
279 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
280 RelocModel = Reloc::PIC_;
282 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
283 RelocModel = Reloc::DynamicNoPIC;
287 // construct LTOModule, hand over ownership of module and target
288 SubtargetFeatures Features;
289 Features.getDefaultSubtargetFeatures(Triple);
290 std::string FeatureStr = Features.getString();
291 // Set a default CPU for Darwin triples.
292 if (_mCpu.empty() && Triple.isOSDarwin()) {
293 if (Triple.getArch() == llvm::Triple::x86_64)
295 else if (Triple.getArch() == llvm::Triple::x86)
298 TargetOptions Options;
299 LTOModule::getTargetOptions(Options);
300 _target = march->createTargetMachine(TripleStr, _mCpu, FeatureStr, Options,
301 RelocModel, CodeModel::Default,
302 CodeGenOpt::Aggressive);
306 void LTOCodeGenerator::
307 applyRestriction(GlobalValue &GV,
308 std::vector<const char*> &mustPreserveList,
309 SmallPtrSet<GlobalValue*, 8> &asmUsed,
311 SmallString<64> Buffer;
312 mangler.getNameWithPrefix(Buffer, &GV, false);
314 if (GV.isDeclaration())
316 if (_mustPreserveSymbols.count(Buffer))
317 mustPreserveList.push_back(GV.getName().data());
318 if (_asmUndefinedRefs.count(Buffer))
322 static void findUsedValues(GlobalVariable *LLVMUsed,
323 SmallPtrSet<GlobalValue*, 8> &UsedValues) {
324 if (LLVMUsed == 0) return;
326 ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
327 for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
328 if (GlobalValue *GV =
329 dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
330 UsedValues.insert(GV);
333 void LTOCodeGenerator::applyScopeRestrictions() {
334 if (_scopeRestrictionsDone) return;
335 Module *mergedModule = _linker.getModule();
337 // Start off with a verification pass.
339 passes.add(createVerifierPass());
341 // mark which symbols can not be internalized
342 MCContext Context(_target->getMCAsmInfo(), _target->getRegisterInfo(), NULL);
343 Mangler mangler(Context, _target);
344 std::vector<const char*> mustPreserveList;
345 SmallPtrSet<GlobalValue*, 8> asmUsed;
347 for (Module::iterator f = mergedModule->begin(),
348 e = mergedModule->end(); f != e; ++f)
349 applyRestriction(*f, mustPreserveList, asmUsed, mangler);
350 for (Module::global_iterator v = mergedModule->global_begin(),
351 e = mergedModule->global_end(); v != e; ++v)
352 applyRestriction(*v, mustPreserveList, asmUsed, mangler);
353 for (Module::alias_iterator a = mergedModule->alias_begin(),
354 e = mergedModule->alias_end(); a != e; ++a)
355 applyRestriction(*a, mustPreserveList, asmUsed, mangler);
357 GlobalVariable *LLVMCompilerUsed =
358 mergedModule->getGlobalVariable("llvm.compiler.used");
359 findUsedValues(LLVMCompilerUsed, asmUsed);
360 if (LLVMCompilerUsed)
361 LLVMCompilerUsed->eraseFromParent();
363 if (!asmUsed.empty()) {
364 llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(_context);
365 std::vector<Constant*> asmUsed2;
366 for (SmallPtrSet<GlobalValue*, 16>::const_iterator i = asmUsed.begin(),
367 e = asmUsed.end(); i !=e; ++i) {
368 GlobalValue *GV = *i;
369 Constant *c = ConstantExpr::getBitCast(GV, i8PTy);
370 asmUsed2.push_back(c);
373 llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, asmUsed2.size());
375 new llvm::GlobalVariable(*mergedModule, ATy, false,
376 llvm::GlobalValue::AppendingLinkage,
377 llvm::ConstantArray::get(ATy, asmUsed2),
378 "llvm.compiler.used");
380 LLVMCompilerUsed->setSection("llvm.metadata");
383 passes.add(createInternalizePass(mustPreserveList));
385 // apply scope restrictions
386 passes.run(*mergedModule);
388 _scopeRestrictionsDone = true;
391 /// Optimize merged modules using various IPO passes
392 bool LTOCodeGenerator::generateObjectFile(raw_ostream &out,
393 std::string &errMsg) {
394 if (this->determineTarget(errMsg))
397 Module* mergedModule = _linker.getModule();
399 // Mark which symbols can not be internalized
400 this->applyScopeRestrictions();
402 // Instantiate the pass manager to organize the passes.
405 // Start off with a verification pass.
406 passes.add(createVerifierPass());
408 // Add an appropriate DataLayout instance for this module...
409 passes.add(new DataLayout(*_target->getDataLayout()));
410 _target->addAnalysisPasses(passes);
412 // Enabling internalize here would use its AllButMain variant. It
413 // keeps only main if it exists and does nothing for libraries. Instead
414 // we create the pass ourselves with the symbol list provided by the linker.
416 PassManagerBuilder().populateLTOPassManager(passes,
417 /*Internalize=*/false,
421 // Make sure everything is still good.
422 passes.add(createVerifierPass());
424 PassManager codeGenPasses;
426 codeGenPasses.add(new DataLayout(*_target->getDataLayout()));
427 _target->addAnalysisPasses(codeGenPasses);
429 formatted_raw_ostream Out(out);
431 // If the bitcode files contain ARC code and were compiled with optimization,
432 // the ObjCARCContractPass must be run, so do it unconditionally here.
433 codeGenPasses.add(createObjCARCContractPass());
435 if (_target->addPassesToEmitFile(codeGenPasses, Out,
436 TargetMachine::CGFT_ObjectFile)) {
437 errMsg = "target file type not supported";
441 // Run our queue of passes all at once now, efficiently.
442 passes.run(*mergedModule);
444 // Run the code generator, and write assembly file
445 codeGenPasses.run(*mergedModule);
447 return false; // success
450 /// setCodeGenDebugOptions - Set codegen debugging options to aid in debugging
452 void LTOCodeGenerator::setCodeGenDebugOptions(const char *options) {
453 for (std::pair<StringRef, StringRef> o = getToken(options);
454 !o.first.empty(); o = getToken(o.second)) {
455 // ParseCommandLineOptions() expects argv[0] to be program name. Lazily add
457 if (_codegenOptions.empty())
458 _codegenOptions.push_back(strdup("libLTO"));
459 _codegenOptions.push_back(strdup(o.first.str().c_str()));