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");
243 else if (strncmp(targetTriple.c_str(), "arm-apple-", 10) == 0) {
244 args.push_back("-arch");
245 args.push_back("arm");
247 else if ((strncmp(targetTriple.c_str(), "armv4t-apple-", 13) == 0) ||
248 (strncmp(targetTriple.c_str(), "thumbv4t-apple-", 15) == 0)) {
249 args.push_back("-arch");
250 args.push_back("armv4t");
252 else if ((strncmp(targetTriple.c_str(), "armv5-apple-", 12) == 0) ||
253 (strncmp(targetTriple.c_str(), "armv5e-apple-", 13) == 0) ||
254 (strncmp(targetTriple.c_str(), "thumbv5-apple-", 14) == 0) ||
255 (strncmp(targetTriple.c_str(), "thumbv5e-apple-", 15) == 0)) {
256 args.push_back("-arch");
257 args.push_back("armv5");
259 else if ((strncmp(targetTriple.c_str(), "armv6-apple-", 12) == 0) ||
260 (strncmp(targetTriple.c_str(), "thumbv6-apple-", 14) == 0)) {
261 args.push_back("-arch");
262 args.push_back("armv6");
265 args.push_back("-c");
266 args.push_back("-x");
267 args.push_back("assembler");
268 args.push_back("-o");
269 args.push_back(objPath.c_str());
270 args.push_back(asmPath.c_str());
274 if ( sys::Program::ExecuteAndWait(gcc, &args[0], 0, 0, 0, 0, &errMsg) ) {
275 errMsg = "error in assembly";
278 return false; // success
283 bool LTOCodeGenerator::determineTarget(std::string& errMsg)
285 if ( _target == NULL ) {
286 // create target machine from info for merged modules
287 Module* mergedModule = _linker.getModule();
288 const TargetMachineRegistry::entry* march =
289 TargetMachineRegistry::getClosestStaticTargetForModule(
290 *mergedModule, errMsg);
294 // construct LTModule, hand over ownership of module and target
295 std::string FeatureStr =
296 getFeatureString(_linker.getModule()->getTargetTriple().c_str());
297 _target = march->CtorFn(*mergedModule, FeatureStr.c_str());
302 void LTOCodeGenerator::applyScopeRestrictions()
304 if ( !_scopeRestrictionsDone ) {
305 Module* mergedModule = _linker.getModule();
307 // Start off with a verification pass.
309 passes.add(createVerifierPass());
311 // mark which symbols can not be internalized
312 if ( !_mustPreserveSymbols.empty() ) {
313 Mangler mangler(*mergedModule,
314 _target->getTargetAsmInfo()->getGlobalPrefix());
315 std::vector<const char*> mustPreserveList;
316 for (Module::iterator f = mergedModule->begin(),
317 e = mergedModule->end(); f != e; ++f) {
318 if ( !f->isDeclaration()
319 && _mustPreserveSymbols.count(mangler.getValueName(f)) )
320 mustPreserveList.push_back(::strdup(f->getName().c_str()));
322 for (Module::global_iterator v = mergedModule->global_begin(),
323 e = mergedModule->global_end(); v != e; ++v) {
324 if ( !v->isDeclaration()
325 && _mustPreserveSymbols.count(mangler.getValueName(v)) )
326 mustPreserveList.push_back(::strdup(v->getName().c_str()));
328 passes.add(createInternalizePass(mustPreserveList));
330 // apply scope restrictions
331 passes.run(*mergedModule);
333 _scopeRestrictionsDone = true;
337 /// Optimize merged modules using various IPO passes
338 bool LTOCodeGenerator::generateAssemblyCode(raw_ostream& out,
341 if ( this->determineTarget(errMsg) )
344 // mark which symbols can not be internalized
345 this->applyScopeRestrictions();
347 Module* mergedModule = _linker.getModule();
349 // If target supports exception handling then enable it now.
350 if ( _target->getTargetAsmInfo()->doesSupportExceptionHandling() )
351 llvm::ExceptionHandling = true;
354 switch( _codeModel ) {
355 case LTO_CODEGEN_PIC_MODEL_STATIC:
356 _target->setRelocationModel(Reloc::Static);
358 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
359 _target->setRelocationModel(Reloc::PIC_);
361 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
362 _target->setRelocationModel(Reloc::DynamicNoPIC);
366 // if options were requested, set them
367 if ( !_codegenOptions.empty() )
368 cl::ParseCommandLineOptions(_codegenOptions.size(),
369 (char**)&_codegenOptions[0]);
371 // Instantiate the pass manager to organize the passes.
374 // Start off with a verification pass.
375 passes.add(createVerifierPass());
377 // Add an appropriate TargetData instance for this module...
378 passes.add(new TargetData(*_target->getTargetData()));
380 // Propagate constants at call sites into the functions they call. This
381 // opens opportunities for globalopt (and inlining) by substituting function
382 // pointers passed as arguments to direct uses of functions.
383 passes.add(createIPSCCPPass());
385 // Now that we internalized some globals, see if we can hack on them!
386 passes.add(createGlobalOptimizerPass());
388 // Linking modules together can lead to duplicated global constants, only
389 // keep one copy of each constant...
390 passes.add(createConstantMergePass());
392 // Remove unused arguments from functions...
393 passes.add(createDeadArgEliminationPass());
395 // Reduce the code after globalopt and ipsccp. Both can open up significant
396 // simplification opportunities, and both can propagate functions through
397 // function pointers. When this happens, we often have to resolve varargs
398 // calls, etc, so let instcombine do this.
399 passes.add(createInstructionCombiningPass());
401 passes.add(createFunctionInliningPass()); // Inline small functions
402 passes.add(createPruneEHPass()); // Remove dead EH info
403 passes.add(createGlobalDCEPass()); // Remove dead functions
405 // If we didn't decide to inline a function, check to see if we can
406 // transform it to pass arguments by value instead of by reference.
407 passes.add(createArgumentPromotionPass());
409 // The IPO passes may leave cruft around. Clean up after them.
410 passes.add(createInstructionCombiningPass());
411 passes.add(createJumpThreadingPass()); // Thread jumps.
412 passes.add(createScalarReplAggregatesPass()); // Break up allocas
414 // Run a few AA driven optimizations here and now, to cleanup the code.
415 passes.add(createFunctionAttrsPass()); // Add nocapture
416 passes.add(createGlobalsModRefPass()); // IP alias analysis
417 passes.add(createLICMPass()); // Hoist loop invariants
418 passes.add(createGVNPass()); // Remove common subexprs
419 passes.add(createMemCpyOptPass()); // Remove dead memcpy's
420 passes.add(createDeadStoreEliminationPass()); // Nuke dead stores
422 // Cleanup and simplify the code after the scalar optimizations.
423 passes.add(createInstructionCombiningPass());
424 passes.add(createJumpThreadingPass()); // Thread jumps.
425 passes.add(createPromoteMemoryToRegisterPass()); // Cleanup after threading.
428 // Delete basic blocks, which optimization passes may have killed...
429 passes.add(createCFGSimplificationPass());
431 // Now that we have optimized the program, discard unreachable functions...
432 passes.add(createGlobalDCEPass());
434 // Make sure everything is still good.
435 passes.add(createVerifierPass());
437 FunctionPassManager* codeGenPasses =
438 new FunctionPassManager(new ExistingModuleProvider(mergedModule));
440 codeGenPasses->add(new TargetData(*_target->getTargetData()));
442 MachineCodeEmitter* mce = NULL;
444 switch (_target->addPassesToEmitFile(*codeGenPasses, out,
445 TargetMachine::AssemblyFile, 3)) {
446 case FileModel::MachOFile:
447 mce = AddMachOWriter(*codeGenPasses, out, *_target);
449 case FileModel::ElfFile:
450 mce = AddELFWriter(*codeGenPasses, out, *_target);
452 case FileModel::AsmFile:
454 case FileModel::Error:
455 case FileModel::None:
456 errMsg = "target file type not supported";
460 if (_target->addPassesToEmitFileFinish(*codeGenPasses, mce, 3)) {
461 errMsg = "target does not support generation of this file type";
465 // Run our queue of passes all at once now, efficiently.
466 passes.run(*mergedModule);
468 // Run the code generator, and write assembly file
469 codeGenPasses->doInitialization();
471 for (Module::iterator
472 it = mergedModule->begin(), e = mergedModule->end(); it != e; ++it)
473 if (!it->isDeclaration())
474 codeGenPasses->run(*it);
476 codeGenPasses->doFinalization();
477 return false; // success
481 /// Optimize merged modules using various IPO passes
482 void LTOCodeGenerator::setCodeGenDebugOptions(const char* options)
484 std::string ops(options);
485 for (std::string o = getToken(ops); !o.empty(); o = getToken(ops)) {
486 // ParseCommandLineOptions() expects argv[0] to be program name.
488 if ( _codegenOptions.empty() )
489 _codegenOptions.push_back("libLTO");
490 _codegenOptions.push_back(strdup(o.c_str()));