1 //===-LTOCodeGenerator.cpp - LLVM Link Time Optimizer ---------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
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.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "LTOModule.h"
16 #include "LTOCodeGenerator.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/ADT/StringExtras.h"
24 #include "llvm/ADT/Triple.h"
25 #include "llvm/Analysis/Passes.h"
26 #include "llvm/Bitcode/ReaderWriter.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/Target/TargetRegistry.h"
36 #include "llvm/Target/TargetSelect.h"
37 #include "llvm/Support/CommandLine.h"
38 #include "llvm/Support/FormattedStream.h"
39 #include "llvm/Support/MemoryBuffer.h"
40 #include "llvm/Support/PassManagerBuilder.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/system_error.h"
47 #include "llvm/Config/config.h"
48 #include <cstdlib>
49 #include <unistd.h>
50 #include <fcntl.h>
51
52
53 using namespace llvm;
54
55 static cl::opt<bool> DisableInline("disable-inlining",
56 cl::desc("Do not run the inliner pass"));
57
58
getVersionString()59 const char* LTOCodeGenerator::getVersionString()
60 {
61 #ifdef LLVM_VERSION_INFO
62 return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
63 #else
64 return PACKAGE_NAME " version " PACKAGE_VERSION;
65 #endif
66 }
67
68
LTOCodeGenerator()69 LTOCodeGenerator::LTOCodeGenerator()
70 : _context(getGlobalContext()),
71 _linker("LinkTimeOptimizer", "ld-temp.o", _context), _target(NULL),
72 _emitDwarfDebugInfo(false), _scopeRestrictionsDone(false),
73 _codeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC),
74 _nativeObjectFile(NULL)
75 {
76 InitializeAllTargets();
77 InitializeAllMCAsmInfos();
78 InitializeAllMCCodeGenInfos();
79 InitializeAllMCRegisterInfos();
80 InitializeAllMCSubtargetInfos();
81 InitializeAllAsmPrinters();
82 }
83
~LTOCodeGenerator()84 LTOCodeGenerator::~LTOCodeGenerator()
85 {
86 delete _target;
87 delete _nativeObjectFile;
88 }
89
90
91
addModule(LTOModule * mod,std::string & errMsg)92 bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg)
93 {
94
95 if(mod->getLLVVMModule()->MaterializeAllPermanently(&errMsg))
96 return true;
97
98 bool ret = _linker.LinkInModule(mod->getLLVVMModule(), &errMsg);
99
100 const std::vector<const char*> &undefs = mod->getAsmUndefinedRefs();
101 for (int i = 0, e = undefs.size(); i != e; ++i)
102 _asmUndefinedRefs[undefs[i]] = 1;
103
104 return ret;
105 }
106
107
setDebugInfo(lto_debug_model debug,std::string & errMsg)108 bool LTOCodeGenerator::setDebugInfo(lto_debug_model debug, std::string& errMsg)
109 {
110 switch (debug) {
111 case LTO_DEBUG_MODEL_NONE:
112 _emitDwarfDebugInfo = false;
113 return false;
114
115 case LTO_DEBUG_MODEL_DWARF:
116 _emitDwarfDebugInfo = true;
117 return false;
118 }
119 errMsg = "unknown debug format";
120 return true;
121 }
122
123
setCodePICModel(lto_codegen_model model,std::string & errMsg)124 bool LTOCodeGenerator::setCodePICModel(lto_codegen_model model,
125 std::string& errMsg)
126 {
127 switch (model) {
128 case LTO_CODEGEN_PIC_MODEL_STATIC:
129 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
130 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
131 _codeModel = model;
132 return false;
133 }
134 errMsg = "unknown pic model";
135 return true;
136 }
137
setCpu(const char * mCpu)138 void LTOCodeGenerator::setCpu(const char* mCpu)
139 {
140 _mCpu = mCpu;
141 }
142
addMustPreserveSymbol(const char * sym)143 void LTOCodeGenerator::addMustPreserveSymbol(const char* sym)
144 {
145 _mustPreserveSymbols[sym] = 1;
146 }
147
148
writeMergedModules(const char * path,std::string & errMsg)149 bool LTOCodeGenerator::writeMergedModules(const char *path,
150 std::string &errMsg) {
151 if (determineTarget(errMsg))
152 return true;
153
154 // mark which symbols can not be internalized
155 applyScopeRestrictions();
156
157 // create output file
158 std::string ErrInfo;
159 tool_output_file Out(path, ErrInfo,
160 raw_fd_ostream::F_Binary);
161 if (!ErrInfo.empty()) {
162 errMsg = "could not open bitcode file for writing: ";
163 errMsg += path;
164 return true;
165 }
166
167 // write bitcode to it
168 WriteBitcodeToFile(_linker.getModule(), Out.os());
169 Out.os().close();
170
171 if (Out.os().has_error()) {
172 errMsg = "could not write bitcode file: ";
173 errMsg += path;
174 Out.os().clear_error();
175 return true;
176 }
177
178 Out.keep();
179 return false;
180 }
181
182
compile_to_file(const char ** name,std::string & errMsg)183 bool LTOCodeGenerator::compile_to_file(const char** name, std::string& errMsg)
184 {
185 // make unique temp .o file to put generated object file
186 sys::PathWithStatus uniqueObjPath("lto-llvm.o");
187 if ( uniqueObjPath.createTemporaryFileOnDisk(false, &errMsg) ) {
188 uniqueObjPath.eraseFromDisk();
189 return true;
190 }
191 sys::RemoveFileOnSignal(uniqueObjPath);
192
193 // generate object file
194 bool genResult = false;
195 tool_output_file objFile(uniqueObjPath.c_str(), errMsg);
196 if (!errMsg.empty())
197 return NULL;
198 genResult = this->generateObjectFile(objFile.os(), errMsg);
199 objFile.os().close();
200 if (objFile.os().has_error()) {
201 objFile.os().clear_error();
202 return true;
203 }
204 objFile.keep();
205 if ( genResult ) {
206 uniqueObjPath.eraseFromDisk();
207 return true;
208 }
209
210 _nativeObjectPath = uniqueObjPath.str();
211 *name = _nativeObjectPath.c_str();
212 return false;
213 }
214
compile(size_t * length,std::string & errMsg)215 const void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg)
216 {
217 const char *name;
218 if (compile_to_file(&name, errMsg))
219 return NULL;
220
221 // remove old buffer if compile() called twice
222 delete _nativeObjectFile;
223
224 // read .o file into memory buffer
225 OwningPtr<MemoryBuffer> BuffPtr;
226 if (error_code ec = MemoryBuffer::getFile(name, BuffPtr, -1, false)) {
227 errMsg = ec.message();
228 return NULL;
229 }
230 _nativeObjectFile = BuffPtr.take();
231
232 // remove temp files
233 sys::Path(_nativeObjectPath).eraseFromDisk();
234
235 // return buffer, unless error
236 if ( _nativeObjectFile == NULL )
237 return NULL;
238 *length = _nativeObjectFile->getBufferSize();
239 return _nativeObjectFile->getBufferStart();
240 }
241
determineTarget(std::string & errMsg)242 bool LTOCodeGenerator::determineTarget(std::string& errMsg)
243 {
244 if ( _target == NULL ) {
245 std::string Triple = _linker.getModule()->getTargetTriple();
246 if (Triple.empty())
247 Triple = sys::getHostTriple();
248
249 // create target machine from info for merged modules
250 const Target *march = TargetRegistry::lookupTarget(Triple, errMsg);
251 if ( march == NULL )
252 return true;
253
254 // The relocation model is actually a static member of TargetMachine
255 // and needs to be set before the TargetMachine is instantiated.
256 Reloc::Model RelocModel = Reloc::Default;
257 switch( _codeModel ) {
258 case LTO_CODEGEN_PIC_MODEL_STATIC:
259 RelocModel = Reloc::Static;
260 break;
261 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
262 RelocModel = Reloc::PIC_;
263 break;
264 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
265 RelocModel = Reloc::DynamicNoPIC;
266 break;
267 }
268
269 // construct LTModule, hand over ownership of module and target
270 SubtargetFeatures Features;
271 Features.getDefaultSubtargetFeatures(llvm::Triple(Triple));
272 std::string FeatureStr = Features.getString();
273 _target = march->createTargetMachine(Triple, _mCpu, FeatureStr,
274 RelocModel);
275 }
276 return false;
277 }
278
applyRestriction(GlobalValue & GV,std::vector<const char * > & mustPreserveList,SmallPtrSet<GlobalValue *,8> & asmUsed,Mangler & mangler)279 void LTOCodeGenerator::applyRestriction(GlobalValue &GV,
280 std::vector<const char*> &mustPreserveList,
281 SmallPtrSet<GlobalValue*, 8> &asmUsed,
282 Mangler &mangler) {
283 SmallString<64> Buffer;
284 mangler.getNameWithPrefix(Buffer, &GV, false);
285
286 if (GV.isDeclaration())
287 return;
288 if (_mustPreserveSymbols.count(Buffer))
289 mustPreserveList.push_back(GV.getName().data());
290 if (_asmUndefinedRefs.count(Buffer))
291 asmUsed.insert(&GV);
292 }
293
findUsedValues(GlobalVariable * LLVMUsed,SmallPtrSet<GlobalValue *,8> & UsedValues)294 static void findUsedValues(GlobalVariable *LLVMUsed,
295 SmallPtrSet<GlobalValue*, 8> &UsedValues) {
296 if (LLVMUsed == 0) return;
297
298 ConstantArray *Inits = dyn_cast<ConstantArray>(LLVMUsed->getInitializer());
299 if (Inits == 0) return;
300
301 for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
302 if (GlobalValue *GV =
303 dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
304 UsedValues.insert(GV);
305 }
306
applyScopeRestrictions()307 void LTOCodeGenerator::applyScopeRestrictions() {
308 if (_scopeRestrictionsDone) return;
309 Module *mergedModule = _linker.getModule();
310
311 // Start off with a verification pass.
312 PassManager passes;
313 passes.add(createVerifierPass());
314
315 // mark which symbols can not be internalized
316 MCContext Context(*_target->getMCAsmInfo(), *_target->getRegisterInfo(),
317 NULL, NULL);
318 Mangler mangler(Context, *_target->getTargetData());
319 std::vector<const char*> mustPreserveList;
320 SmallPtrSet<GlobalValue*, 8> asmUsed;
321
322 for (Module::iterator f = mergedModule->begin(),
323 e = mergedModule->end(); f != e; ++f)
324 applyRestriction(*f, mustPreserveList, asmUsed, mangler);
325 for (Module::global_iterator v = mergedModule->global_begin(),
326 e = mergedModule->global_end(); v != e; ++v)
327 applyRestriction(*v, mustPreserveList, asmUsed, mangler);
328 for (Module::alias_iterator a = mergedModule->alias_begin(),
329 e = mergedModule->alias_end(); a != e; ++a)
330 applyRestriction(*a, mustPreserveList, asmUsed, mangler);
331
332 GlobalVariable *LLVMCompilerUsed =
333 mergedModule->getGlobalVariable("llvm.compiler.used");
334 findUsedValues(LLVMCompilerUsed, asmUsed);
335 if (LLVMCompilerUsed)
336 LLVMCompilerUsed->eraseFromParent();
337
338 llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(_context);
339 std::vector<Constant*> asmUsed2;
340 for (SmallPtrSet<GlobalValue*, 16>::const_iterator i = asmUsed.begin(),
341 e = asmUsed.end(); i !=e; ++i) {
342 GlobalValue *GV = *i;
343 Constant *c = ConstantExpr::getBitCast(GV, i8PTy);
344 asmUsed2.push_back(c);
345 }
346
347 llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, asmUsed2.size());
348 LLVMCompilerUsed =
349 new llvm::GlobalVariable(*mergedModule, ATy, false,
350 llvm::GlobalValue::AppendingLinkage,
351 llvm::ConstantArray::get(ATy, asmUsed2),
352 "llvm.compiler.used");
353
354 LLVMCompilerUsed->setSection("llvm.metadata");
355
356 passes.add(createInternalizePass(mustPreserveList));
357
358 // apply scope restrictions
359 passes.run(*mergedModule);
360
361 _scopeRestrictionsDone = true;
362 }
363
364 /// Optimize merged modules using various IPO passes
generateObjectFile(raw_ostream & out,std::string & errMsg)365 bool LTOCodeGenerator::generateObjectFile(raw_ostream &out,
366 std::string &errMsg) {
367 if ( this->determineTarget(errMsg) )
368 return true;
369
370 // mark which symbols can not be internalized
371 this->applyScopeRestrictions();
372
373 Module* mergedModule = _linker.getModule();
374
375 // if options were requested, set them
376 if ( !_codegenOptions.empty() )
377 cl::ParseCommandLineOptions(_codegenOptions.size(),
378 const_cast<char **>(&_codegenOptions[0]));
379
380 // Instantiate the pass manager to organize the passes.
381 PassManager passes;
382
383 // Start off with a verification pass.
384 passes.add(createVerifierPass());
385
386 // Add an appropriate TargetData instance for this module...
387 passes.add(new TargetData(*_target->getTargetData()));
388
389 PassManagerBuilder().populateLTOPassManager(passes, /*Internalize=*/ false,
390 !DisableInline);
391
392 // Make sure everything is still good.
393 passes.add(createVerifierPass());
394
395 FunctionPassManager *codeGenPasses = new FunctionPassManager(mergedModule);
396
397 codeGenPasses->add(new TargetData(*_target->getTargetData()));
398
399 formatted_raw_ostream Out(out);
400
401 if (_target->addPassesToEmitFile(*codeGenPasses, Out,
402 TargetMachine::CGFT_ObjectFile,
403 CodeGenOpt::Aggressive)) {
404 errMsg = "target file type not supported";
405 return true;
406 }
407
408 // Run our queue of passes all at once now, efficiently.
409 passes.run(*mergedModule);
410
411 // Run the code generator, and write assembly file
412 codeGenPasses->doInitialization();
413
414 for (Module::iterator
415 it = mergedModule->begin(), e = mergedModule->end(); it != e; ++it)
416 if (!it->isDeclaration())
417 codeGenPasses->run(*it);
418
419 codeGenPasses->doFinalization();
420 delete codeGenPasses;
421
422 return false; // success
423 }
424
425
426 /// Optimize merged modules using various IPO passes
setCodeGenDebugOptions(const char * options)427 void LTOCodeGenerator::setCodeGenDebugOptions(const char* options)
428 {
429 for (std::pair<StringRef, StringRef> o = getToken(options);
430 !o.first.empty(); o = getToken(o.second)) {
431 // ParseCommandLineOptions() expects argv[0] to be program name.
432 // Lazily add that.
433 if ( _codegenOptions.empty() )
434 _codegenOptions.push_back("libLTO");
435 _codegenOptions.push_back(strdup(o.first.str().c_str()));
436 }
437 }
438