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