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 "LTOModule.h"
16 #include "LTOCodeGenerator.h"
19 #include "llvm/Module.h"
20 #include "llvm/PassManager.h"
21 #include "llvm/Linker.h"
22 #include "llvm/Constants.h"
23 #include "llvm/DerivedTypes.h"
24 #include "llvm/ModuleProvider.h"
25 #include "llvm/Bitcode/ReaderWriter.h"
26 #include "llvm/Support/CommandLine.h"
27 #include "llvm/Support/SystemUtils.h"
28 #include "llvm/Support/Mangler.h"
29 #include "llvm/Support/MemoryBuffer.h"
30 #include "llvm/Support/raw_ostream.h"
31 #include "llvm/System/Signals.h"
32 #include "llvm/Analysis/Passes.h"
33 #include "llvm/Analysis/LoopPass.h"
34 #include "llvm/Analysis/Verifier.h"
35 #include "llvm/CodeGen/FileWriters.h"
36 #include "llvm/Target/SubtargetFeature.h"
37 #include "llvm/Target/TargetOptions.h"
38 #include "llvm/Target/TargetData.h"
39 #include "llvm/Target/TargetMachine.h"
40 #include "llvm/Target/TargetMachineRegistry.h"
41 #include "llvm/Target/TargetAsmInfo.h"
42 #include "llvm/Transforms/IPO.h"
43 #include "llvm/Transforms/Scalar.h"
44 #include "llvm/ADT/StringExtras.h"
45 #include "llvm/Config/config.h"
56 static cl::opt<bool> DisableInline("disable-inlining",
57 cl::desc("Do not run the inliner pass"));
60 const char* LTOCodeGenerator::getVersionString()
62 #ifdef LLVM_VERSION_INFO
63 return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
65 return PACKAGE_NAME " version " PACKAGE_VERSION;
70 LTOCodeGenerator::LTOCodeGenerator()
71 : _linker("LinkTimeOptimizer", "ld-temp.o"), _target(NULL),
72 _emitDwarfDebugInfo(false), _scopeRestrictionsDone(false),
73 _codeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC),
74 _nativeObjectFile(NULL)
79 LTOCodeGenerator::~LTOCodeGenerator()
82 delete _nativeObjectFile;
87 bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg)
89 return _linker.LinkInModule(mod->getLLVVMModule(), &errMsg);
93 bool LTOCodeGenerator::setDebugInfo(lto_debug_model debug, std::string& errMsg)
96 case LTO_DEBUG_MODEL_NONE:
97 _emitDwarfDebugInfo = false;
100 case LTO_DEBUG_MODEL_DWARF:
101 _emitDwarfDebugInfo = true;
104 errMsg = "unknown debug format";
109 bool LTOCodeGenerator::setCodePICModel(lto_codegen_model model,
113 case LTO_CODEGEN_PIC_MODEL_STATIC:
114 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
115 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
119 errMsg = "unknown pic model";
123 void LTOCodeGenerator::addMustPreserveSymbol(const char* sym)
125 _mustPreserveSymbols[sym] = 1;
129 bool LTOCodeGenerator::writeMergedModules(const char* path, std::string& errMsg)
131 if ( this->determineTarget(errMsg) )
134 // mark which symbols can not be internalized
135 this->applyScopeRestrictions();
137 // create output file
138 std::ofstream out(path, std::ios_base::out|std::ios::trunc|std::ios::binary);
140 errMsg = "could not open bitcode file for writing: ";
145 // write bitcode to it
146 WriteBitcodeToFile(_linker.getModule(), out);
148 errMsg = "could not write bitcode file: ";
157 const void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg)
159 // make unique temp .s file to put generated assembly code
160 sys::Path uniqueAsmPath("lto-llvm.s");
161 if ( uniqueAsmPath.createTemporaryFileOnDisk(true, &errMsg) )
163 sys::RemoveFileOnSignal(uniqueAsmPath);
165 // generate assembly code
166 bool genResult = false;
168 raw_fd_ostream asmFile(uniqueAsmPath.c_str(), false, errMsg);
171 genResult = this->generateAssemblyCode(asmFile, errMsg);
174 if ( uniqueAsmPath.exists() )
175 uniqueAsmPath.eraseFromDisk();
179 // make unique temp .o file to put generated object file
180 sys::PathWithStatus uniqueObjPath("lto-llvm.o");
181 if ( uniqueObjPath.createTemporaryFileOnDisk(true, &errMsg) ) {
182 if ( uniqueAsmPath.exists() )
183 uniqueAsmPath.eraseFromDisk();
186 sys::RemoveFileOnSignal(uniqueObjPath);
188 // assemble the assembly code
189 const std::string& uniqueObjStr = uniqueObjPath.toString();
190 bool asmResult = this->assemble(uniqueAsmPath.toString(),
191 uniqueObjStr, errMsg);
193 // remove old buffer if compile() called twice
194 delete _nativeObjectFile;
196 // read .o file into memory buffer
197 _nativeObjectFile = MemoryBuffer::getFile(uniqueObjStr.c_str(),&errMsg);
201 uniqueAsmPath.eraseFromDisk();
202 uniqueObjPath.eraseFromDisk();
204 // return buffer, unless error
205 if ( _nativeObjectFile == NULL )
207 *length = _nativeObjectFile->getBufferSize();
208 return _nativeObjectFile->getBufferStart();
212 bool LTOCodeGenerator::assemble(const std::string& asmPath,
213 const std::string& objPath, std::string& errMsg)
215 // find compiler driver
216 const sys::Path gcc = sys::Program::FindProgramByName("gcc");
217 if ( gcc.isEmpty() ) {
218 errMsg = "can't locate gcc";
222 // build argument list
223 std::vector<const char*> args;
224 std::string targetTriple = _linker.getModule()->getTargetTriple();
225 args.push_back(gcc.c_str());
226 if ( targetTriple.find("darwin") != targetTriple.size() ) {
227 if (strncmp(targetTriple.c_str(), "i386-apple-", 11) == 0) {
228 args.push_back("-arch");
229 args.push_back("i386");
231 else if (strncmp(targetTriple.c_str(), "x86_64-apple-", 13) == 0) {
232 args.push_back("-arch");
233 args.push_back("x86_64");
235 else if (strncmp(targetTriple.c_str(), "powerpc-apple-", 14) == 0) {
236 args.push_back("-arch");
237 args.push_back("ppc");
239 else if (strncmp(targetTriple.c_str(), "powerpc64-apple-", 16) == 0) {
240 args.push_back("-arch");
241 args.push_back("ppc64");
244 args.push_back("-c");
245 args.push_back("-x");
246 args.push_back("assembler");
247 args.push_back("-o");
248 args.push_back(objPath.c_str());
249 args.push_back(asmPath.c_str());
253 if ( sys::Program::ExecuteAndWait(gcc, &args[0], 0, 0, 0, 0, &errMsg) ) {
254 errMsg = "error in assembly";
257 return false; // success
262 bool LTOCodeGenerator::determineTarget(std::string& errMsg)
264 if ( _target == NULL ) {
265 // create target machine from info for merged modules
266 Module* mergedModule = _linker.getModule();
267 const TargetMachineRegistry::entry* march =
268 TargetMachineRegistry::getClosestStaticTargetForModule(
269 *mergedModule, errMsg);
273 // construct LTModule, hand over ownership of module and target
274 std::string FeatureStr =
275 getFeatureString(_linker.getModule()->getTargetTriple().c_str());
276 _target = march->CtorFn(*mergedModule, FeatureStr.c_str());
281 void LTOCodeGenerator::applyScopeRestrictions()
283 if ( !_scopeRestrictionsDone ) {
284 Module* mergedModule = _linker.getModule();
286 // Start off with a verification pass.
288 passes.add(createVerifierPass());
290 // mark which symbols can not be internalized
291 if ( !_mustPreserveSymbols.empty() ) {
292 Mangler mangler(*mergedModule,
293 _target->getTargetAsmInfo()->getGlobalPrefix());
294 std::vector<const char*> mustPreserveList;
295 for (Module::iterator f = mergedModule->begin(),
296 e = mergedModule->end(); f != e; ++f) {
297 if ( !f->isDeclaration()
298 && _mustPreserveSymbols.count(mangler.getValueName(f)) )
299 mustPreserveList.push_back(::strdup(f->getName().c_str()));
301 for (Module::global_iterator v = mergedModule->global_begin(),
302 e = mergedModule->global_end(); v != e; ++v) {
303 if ( !v->isDeclaration()
304 && _mustPreserveSymbols.count(mangler.getValueName(v)) )
305 mustPreserveList.push_back(::strdup(v->getName().c_str()));
307 passes.add(createInternalizePass(mustPreserveList));
309 // apply scope restrictions
310 passes.run(*mergedModule);
312 _scopeRestrictionsDone = true;
316 /// Optimize merged modules using various IPO passes
317 bool LTOCodeGenerator::generateAssemblyCode(raw_ostream& out,
320 if ( this->determineTarget(errMsg) )
323 // mark which symbols can not be internalized
324 this->applyScopeRestrictions();
326 Module* mergedModule = _linker.getModule();
328 // If target supports exception handling then enable it now.
329 if ( _target->getTargetAsmInfo()->doesSupportExceptionHandling() )
330 llvm::ExceptionHandling = true;
333 switch( _codeModel ) {
334 case LTO_CODEGEN_PIC_MODEL_STATIC:
335 _target->setRelocationModel(Reloc::Static);
337 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
338 _target->setRelocationModel(Reloc::PIC_);
340 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
341 _target->setRelocationModel(Reloc::DynamicNoPIC);
345 // if options were requested, set them
346 if ( !_codegenOptions.empty() )
347 cl::ParseCommandLineOptions(_codegenOptions.size(),
348 (char**)&_codegenOptions[0]);
350 // Instantiate the pass manager to organize the passes.
353 // Start off with a verification pass.
354 passes.add(createVerifierPass());
356 // Add an appropriate TargetData instance for this module...
357 passes.add(new TargetData(*_target->getTargetData()));
359 // Propagate constants at call sites into the functions they call. This
360 // opens opportunities for globalopt (and inlining) by substituting function
361 // pointers passed as arguments to direct uses of functions.
362 passes.add(createIPSCCPPass());
364 // Now that we internalized some globals, see if we can hack on them!
365 passes.add(createGlobalOptimizerPass());
367 // Linking modules together can lead to duplicated global constants, only
368 // keep one copy of each constant...
369 passes.add(createConstantMergePass());
371 // Remove unused arguments from functions...
372 passes.add(createDeadArgEliminationPass());
374 // Reduce the code after globalopt and ipsccp. Both can open up significant
375 // simplification opportunities, and both can propagate functions through
376 // function pointers. When this happens, we often have to resolve varargs
377 // calls, etc, so let instcombine do this.
378 passes.add(createInstructionCombiningPass());
380 passes.add(createFunctionInliningPass()); // Inline small functions
381 passes.add(createPruneEHPass()); // Remove dead EH info
382 passes.add(createGlobalDCEPass()); // Remove dead functions
384 // If we didn't decide to inline a function, check to see if we can
385 // transform it to pass arguments by value instead of by reference.
386 passes.add(createArgumentPromotionPass());
388 // The IPO passes may leave cruft around. Clean up after them.
389 passes.add(createInstructionCombiningPass());
390 passes.add(createJumpThreadingPass()); // Thread jumps.
391 passes.add(createScalarReplAggregatesPass()); // Break up allocas
393 // Run a few AA driven optimizations here and now, to cleanup the code.
394 passes.add(createFunctionAttrsPass()); // Add nocapture
395 passes.add(createGlobalsModRefPass()); // IP alias analysis
396 passes.add(createLICMPass()); // Hoist loop invariants
397 passes.add(createGVNPass()); // Remove common subexprs
398 passes.add(createMemCpyOptPass()); // Remove dead memcpy's
399 passes.add(createDeadStoreEliminationPass()); // Nuke dead stores
401 // Cleanup and simplify the code after the scalar optimizations.
402 passes.add(createInstructionCombiningPass());
403 passes.add(createJumpThreadingPass()); // Thread jumps.
404 passes.add(createPromoteMemoryToRegisterPass()); // Cleanup after threading.
407 // Delete basic blocks, which optimization passes may have killed...
408 passes.add(createCFGSimplificationPass());
410 // Now that we have optimized the program, discard unreachable functions...
411 passes.add(createGlobalDCEPass());
413 // Make sure everything is still good.
414 passes.add(createVerifierPass());
416 FunctionPassManager* codeGenPasses =
417 new FunctionPassManager(new ExistingModuleProvider(mergedModule));
419 codeGenPasses->add(new TargetData(*_target->getTargetData()));
421 MachineCodeEmitter* mce = NULL;
423 switch (_target->addPassesToEmitFile(*codeGenPasses, out,
424 TargetMachine::AssemblyFile, false)) {
425 case FileModel::MachOFile:
426 mce = AddMachOWriter(*codeGenPasses, out, *_target);
428 case FileModel::ElfFile:
429 mce = AddELFWriter(*codeGenPasses, out, *_target);
431 case FileModel::AsmFile:
433 case FileModel::Error:
434 case FileModel::None:
435 errMsg = "target file type not supported";
439 if (_target->addPassesToEmitFileFinish(*codeGenPasses, mce, false)) {
440 errMsg = "target does not support generation of this file type";
444 // Run our queue of passes all at once now, efficiently.
445 passes.run(*mergedModule);
447 // Run the code generator, and write assembly file
448 codeGenPasses->doInitialization();
450 for (Module::iterator
451 it = mergedModule->begin(), e = mergedModule->end(); it != e; ++it)
452 if (!it->isDeclaration())
453 codeGenPasses->run(*it);
455 codeGenPasses->doFinalization();
456 return false; // success
460 /// Optimize merged modules using various IPO passes
461 void LTOCodeGenerator::setCodeGenDebugOptions(const char* options)
463 std::string ops(options);
464 for (std::string o = getToken(ops); !o.empty(); o = getToken(ops)) {
465 // ParseCommandLineOptions() expects argv[0] to be program name.
467 if ( _codegenOptions.empty() )
468 _codegenOptions.push_back("libLTO");
469 _codegenOptions.push_back(strdup(o.c_str()));