llvm.org GIT mirror llvm / release_31 tools / lto / LTOCodeGenerator.cpp
release_31

Tree @release_31 (Download .tar.gz)

LTOCodeGenerator.cpp @release_31raw · history · blame

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
//===-LTOCodeGenerator.cpp - LLVM Link Time Optimizer ---------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Link Time Optimization library. This library is
// intended to be used by linker to optimize code at link time.
//
//===----------------------------------------------------------------------===//

#include "LTOCodeGenerator.h"
#include "LTOModule.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Linker.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/PassManager.h"
#include "llvm/Analysis/Passes.h"
#include "llvm/Analysis/Verifier.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/Config/config.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/SubtargetFeature.h"
#include "llvm/Target/Mangler.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/IPO/PassManagerBuilder.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FormattedStream.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/ToolOutputFile.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/Signals.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/system_error.h"
#include "llvm/ADT/StringExtras.h"
using namespace llvm;

static cl::opt<bool> DisableInline("disable-inlining", cl::init(false),
  cl::desc("Do not run the inliner pass"));

static cl::opt<bool> DisableGVNLoadPRE("disable-gvn-loadpre", cl::init(false),
  cl::desc("Do not run the GVN load PRE pass"));

const char* LTOCodeGenerator::getVersionString() {
#ifdef LLVM_VERSION_INFO
  return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
#else
  return PACKAGE_NAME " version " PACKAGE_VERSION;
#endif
}

LTOCodeGenerator::LTOCodeGenerator()
  : _context(getGlobalContext()),
    _linker("LinkTimeOptimizer", "ld-temp.o", _context), _target(NULL),
    _emitDwarfDebugInfo(false), _scopeRestrictionsDone(false),
    _codeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC),
    _nativeObjectFile(NULL) {
  InitializeAllTargets();
  InitializeAllTargetMCs();
  InitializeAllAsmPrinters();
}

LTOCodeGenerator::~LTOCodeGenerator() {
  delete _target;
  delete _nativeObjectFile;

  for (std::vector<char*>::iterator I = _codegenOptions.begin(),
         E = _codegenOptions.end(); I != E; ++I)
    free(*I);
}

bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg) {
  bool ret = _linker.LinkInModule(mod->getLLVVMModule(), &errMsg);

  const std::vector<const char*> &undefs = mod->getAsmUndefinedRefs();
  for (int i = 0, e = undefs.size(); i != e; ++i)
    _asmUndefinedRefs[undefs[i]] = 1;

  return ret;
}

bool LTOCodeGenerator::setDebugInfo(lto_debug_model debug,
                                    std::string& errMsg) {
  switch (debug) {
  case LTO_DEBUG_MODEL_NONE:
    _emitDwarfDebugInfo = false;
    return false;

  case LTO_DEBUG_MODEL_DWARF:
    _emitDwarfDebugInfo = true;
    return false;
  }
  llvm_unreachable("Unknown debug format!");
}

bool LTOCodeGenerator::setCodePICModel(lto_codegen_model model,
                                       std::string& errMsg) {
  switch (model) {
  case LTO_CODEGEN_PIC_MODEL_STATIC:
  case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
  case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
    _codeModel = model;
    return false;
  }
  llvm_unreachable("Unknown PIC model!");
}

bool LTOCodeGenerator::writeMergedModules(const char *path,
                                          std::string &errMsg) {
  if (determineTarget(errMsg))
    return true;

  // mark which symbols can not be internalized
  applyScopeRestrictions();

  // create output file
  std::string ErrInfo;
  tool_output_file Out(path, ErrInfo,
                       raw_fd_ostream::F_Binary);
  if (!ErrInfo.empty()) {
    errMsg = "could not open bitcode file for writing: ";
    errMsg += path;
    return true;
  }

  // write bitcode to it
  WriteBitcodeToFile(_linker.getModule(), Out.os());
  Out.os().close();

  if (Out.os().has_error()) {
    errMsg = "could not write bitcode file: ";
    errMsg += path;
    Out.os().clear_error();
    return true;
  }

  Out.keep();
  return false;
}

bool LTOCodeGenerator::compile_to_file(const char** name, std::string& errMsg) {
  // make unique temp .o file to put generated object file
  sys::PathWithStatus uniqueObjPath("lto-llvm.o");
  if ( uniqueObjPath.createTemporaryFileOnDisk(false, &errMsg) ) {
    uniqueObjPath.eraseFromDisk();
    return true;
  }
  sys::RemoveFileOnSignal(uniqueObjPath);

  // generate object file
  bool genResult = false;
  tool_output_file objFile(uniqueObjPath.c_str(), errMsg);
  if (!errMsg.empty())
    return true;

  genResult = this->generateObjectFile(objFile.os(), errMsg);
  objFile.os().close();
  if (objFile.os().has_error()) {
    objFile.os().clear_error();
    return true;
  }

  objFile.keep();
  if ( genResult ) {
    uniqueObjPath.eraseFromDisk();
    return true;
  }

  _nativeObjectPath = uniqueObjPath.str();
  *name = _nativeObjectPath.c_str();
  return false;
}

const void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg) {
  const char *name;
  if (compile_to_file(&name, errMsg))
    return NULL;

  // remove old buffer if compile() called twice
  delete _nativeObjectFile;

  // read .o file into memory buffer
  OwningPtr<MemoryBuffer> BuffPtr;
  if (error_code ec = MemoryBuffer::getFile(name, BuffPtr, -1, false)) {
    errMsg = ec.message();
    return NULL;
  }
  _nativeObjectFile = BuffPtr.take();

  // remove temp files
  sys::Path(_nativeObjectPath).eraseFromDisk();

  // return buffer, unless error
  if ( _nativeObjectFile == NULL )
    return NULL;
  *length = _nativeObjectFile->getBufferSize();
  return _nativeObjectFile->getBufferStart();
}

bool LTOCodeGenerator::determineTarget(std::string& errMsg) {
  if ( _target == NULL ) {
    std::string Triple = _linker.getModule()->getTargetTriple();
    if (Triple.empty())
      Triple = sys::getDefaultTargetTriple();

    // create target machine from info for merged modules
    const Target *march = TargetRegistry::lookupTarget(Triple, errMsg);
    if ( march == NULL )
      return true;

    // The relocation model is actually a static member of TargetMachine and
    // needs to be set before the TargetMachine is instantiated.
    Reloc::Model RelocModel = Reloc::Default;
    switch( _codeModel ) {
    case LTO_CODEGEN_PIC_MODEL_STATIC:
      RelocModel = Reloc::Static;
      break;
    case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
      RelocModel = Reloc::PIC_;
      break;
    case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
      RelocModel = Reloc::DynamicNoPIC;
      break;
    }

    // construct LTOModule, hand over ownership of module and target
    SubtargetFeatures Features;
    Features.getDefaultSubtargetFeatures(llvm::Triple(Triple));
    std::string FeatureStr = Features.getString();
    TargetOptions Options;
    _target = march->createTargetMachine(Triple, _mCpu, FeatureStr, Options,
                                         RelocModel);
  }
  return false;
}

void LTOCodeGenerator::
applyRestriction(GlobalValue &GV,
                 std::vector<const char*> &mustPreserveList,
                 SmallPtrSet<GlobalValue*, 8> &asmUsed,
                 Mangler &mangler) {
  SmallString<64> Buffer;
  mangler.getNameWithPrefix(Buffer, &GV, false);

  if (GV.isDeclaration())
    return;
  if (_mustPreserveSymbols.count(Buffer))
    mustPreserveList.push_back(GV.getName().data());
  if (_asmUndefinedRefs.count(Buffer))
    asmUsed.insert(&GV);
}

static void findUsedValues(GlobalVariable *LLVMUsed,
                           SmallPtrSet<GlobalValue*, 8> &UsedValues) {
  if (LLVMUsed == 0) return;

  ConstantArray *Inits = dyn_cast<ConstantArray>(LLVMUsed->getInitializer());
  if (Inits == 0) return;

  for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
    if (GlobalValue *GV =
        dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
      UsedValues.insert(GV);
}

void LTOCodeGenerator::applyScopeRestrictions() {
  if (_scopeRestrictionsDone) return;
  Module *mergedModule = _linker.getModule();

  // Start off with a verification pass.
  PassManager passes;
  passes.add(createVerifierPass());

  // mark which symbols can not be internalized
  MCContext Context(*_target->getMCAsmInfo(), *_target->getRegisterInfo(),NULL);
  Mangler mangler(Context, *_target->getTargetData());
  std::vector<const char*> mustPreserveList;
  SmallPtrSet<GlobalValue*, 8> asmUsed;

  for (Module::iterator f = mergedModule->begin(),
         e = mergedModule->end(); f != e; ++f)
    applyRestriction(*f, mustPreserveList, asmUsed, mangler);
  for (Module::global_iterator v = mergedModule->global_begin(),
         e = mergedModule->global_end(); v !=  e; ++v)
    applyRestriction(*v, mustPreserveList, asmUsed, mangler);
  for (Module::alias_iterator a = mergedModule->alias_begin(),
         e = mergedModule->alias_end(); a != e; ++a)
    applyRestriction(*a, mustPreserveList, asmUsed, mangler);

  GlobalVariable *LLVMCompilerUsed =
    mergedModule->getGlobalVariable("llvm.compiler.used");
  findUsedValues(LLVMCompilerUsed, asmUsed);
  if (LLVMCompilerUsed)
    LLVMCompilerUsed->eraseFromParent();

  llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(_context);
  std::vector<Constant*> asmUsed2;
  for (SmallPtrSet<GlobalValue*, 16>::const_iterator i = asmUsed.begin(),
         e = asmUsed.end(); i !=e; ++i) {
    GlobalValue *GV = *i;
    Constant *c = ConstantExpr::getBitCast(GV, i8PTy);
    asmUsed2.push_back(c);
  }

  llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, asmUsed2.size());
  LLVMCompilerUsed =
    new llvm::GlobalVariable(*mergedModule, ATy, false,
                             llvm::GlobalValue::AppendingLinkage,
                             llvm::ConstantArray::get(ATy, asmUsed2),
                             "llvm.compiler.used");

  LLVMCompilerUsed->setSection("llvm.metadata");

  passes.add(createInternalizePass(mustPreserveList));

  // apply scope restrictions
  passes.run(*mergedModule);

  _scopeRestrictionsDone = true;
}

/// Optimize merged modules using various IPO passes
bool LTOCodeGenerator::generateObjectFile(raw_ostream &out,
                                          std::string &errMsg) {
  if ( this->determineTarget(errMsg) )
    return true;

  Module* mergedModule = _linker.getModule();

  // if options were requested, set them
  if ( !_codegenOptions.empty() )
    cl::ParseCommandLineOptions(_codegenOptions.size(),
                                const_cast<char **>(&_codegenOptions[0]));

  // mark which symbols can not be internalized
  this->applyScopeRestrictions();

  // Instantiate the pass manager to organize the passes.
  PassManager passes;

  // Start off with a verification pass.
  passes.add(createVerifierPass());

  // Add an appropriate TargetData instance for this module...
  passes.add(new TargetData(*_target->getTargetData()));

  // Enabling internalize here would use its AllButMain variant. It
  // keeps only main if it exists and does nothing for libraries. Instead
  // we create the pass ourselves with the symbol list provided by the linker.
  PassManagerBuilder().populateLTOPassManager(passes, /*Internalize=*/false,
                                              !DisableInline,
                                              DisableGVNLoadPRE);

  // Make sure everything is still good.
  passes.add(createVerifierPass());

  FunctionPassManager *codeGenPasses = new FunctionPassManager(mergedModule);

  codeGenPasses->add(new TargetData(*_target->getTargetData()));

  formatted_raw_ostream Out(out);

  if (_target->addPassesToEmitFile(*codeGenPasses, Out,
                                   TargetMachine::CGFT_ObjectFile,
                                   CodeGenOpt::Aggressive)) {
    errMsg = "target file type not supported";
    return true;
  }

  // Run our queue of passes all at once now, efficiently.
  passes.run(*mergedModule);

  // Run the code generator, and write assembly file
  codeGenPasses->doInitialization();

  for (Module::iterator
         it = mergedModule->begin(), e = mergedModule->end(); it != e; ++it)
    if (!it->isDeclaration())
      codeGenPasses->run(*it);

  codeGenPasses->doFinalization();
  delete codeGenPasses;

  return false; // success
}

/// setCodeGenDebugOptions - Set codegen debugging options to aid in debugging
/// LTO problems.
void LTOCodeGenerator::setCodeGenDebugOptions(const char *options) {
  for (std::pair<StringRef, StringRef> o = getToken(options);
       !o.first.empty(); o = getToken(o.second)) {
    // ParseCommandLineOptions() expects argv[0] to be program name. Lazily add
    // that.
    if ( _codegenOptions.empty() )
      _codegenOptions.push_back(strdup("libLTO"));
    _codegenOptions.push_back(strdup(o.first.str().c_str()));
  }
}