aboutsummaryrefslogtreecommitdiffstats
path: root/lib/LTO/LTOCodeGenerator.cpp
blob: c663d43fe7fdec56979651a2bde5f3052427c54a (plain)
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
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
//===-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 "llvm/LTO/LTOCodeGenerator.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Analysis/Passes.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/CodeGen/RuntimeLibcalls.h"
#include "llvm/Config/config.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Verifier.h"
#include "llvm/InitializePasses.h"
#include "llvm/LTO/LTOModule.h"
#include "llvm/Linker/Linker.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/SubtargetFeature.h"
#include "llvm/PassManager.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/FormattedStream.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Signals.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/ToolOutputFile.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetLibraryInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetSubtargetInfo.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/IPO/PassManagerBuilder.h"
#include "llvm/Transforms/ObjCARC.h"
#include <system_error>
using namespace llvm;

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()), IRLinker(new Module("ld-temp.o", Context)) {
  initialize();
}

LTOCodeGenerator::LTOCodeGenerator(std::unique_ptr<LLVMContext> Context)
    : OwnedContext(std::move(Context)), Context(*OwnedContext),
      IRLinker(new Module("ld-temp.o", *OwnedContext)) {
  initialize();
}

void LTOCodeGenerator::initialize() {
  TargetMach = nullptr;
  EmitDwarfDebugInfo = false;
  ScopeRestrictionsDone = false;
  CodeModel = LTO_CODEGEN_PIC_MODEL_DEFAULT;
  DiagHandler = nullptr;
  DiagContext = nullptr;

  initializeLTOPasses();
}

LTOCodeGenerator::~LTOCodeGenerator() {
  delete TargetMach;
  TargetMach = nullptr;

  IRLinker.deleteModule();

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

// Initialize LTO passes. Please keep this funciton in sync with
// PassManagerBuilder::populateLTOPassManager(), and make sure all LTO
// passes are initialized.
void LTOCodeGenerator::initializeLTOPasses() {
  PassRegistry &R = *PassRegistry::getPassRegistry();

  initializeInternalizePassPass(R);
  initializeIPSCCPPass(R);
  initializeGlobalOptPass(R);
  initializeConstantMergePass(R);
  initializeDAHPass(R);
  initializeInstCombinerPass(R);
  initializeSimpleInlinerPass(R);
  initializePruneEHPass(R);
  initializeGlobalDCEPass(R);
  initializeArgPromotionPass(R);
  initializeJumpThreadingPass(R);
  initializeSROAPass(R);
  initializeSROA_DTPass(R);
  initializeSROA_SSAUpPass(R);
  initializeFunctionAttrsPass(R);
  initializeGlobalsModRefPass(R);
  initializeLICMPass(R);
  initializeMergedLoadStoreMotionPass(R);
  initializeGVNPass(R);
  initializeMemCpyOptPass(R);
  initializeDCEPass(R);
  initializeCFGSimplifyPassPass(R);
}

bool LTOCodeGenerator::addModule(LTOModule *mod) {
  assert(&mod->getModule().getContext() == &Context &&
         "Expected module in same context");

  bool ret = IRLinker.linkInModule(&mod->getModule());

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

  return !ret;
}

void LTOCodeGenerator::setTargetOptions(TargetOptions options) {
  Options = options;
}

void LTOCodeGenerator::setDebugInfo(lto_debug_model debug) {
  switch (debug) {
  case LTO_DEBUG_MODEL_NONE:
    EmitDwarfDebugInfo = false;
    return;

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

void LTOCodeGenerator::setCodePICModel(lto_codegen_model model) {
  switch (model) {
  case LTO_CODEGEN_PIC_MODEL_STATIC:
  case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
  case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
  case LTO_CODEGEN_PIC_MODEL_DEFAULT:
    CodeModel = model;
    return;
  }
  llvm_unreachable("Unknown PIC model!");
}

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

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

  // create output file
  std::error_code EC;
  tool_output_file Out(path, EC, sys::fs::F_None);
  if (EC) {
    errMsg = "could not open bitcode file for writing: ";
    errMsg += path;
    return false;
  }

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

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

  Out.keep();
  return true;
}

bool LTOCodeGenerator::compile_to_file(const char** name,
                                       bool disableOpt,
                                       bool disableInline,
                                       bool disableGVNLoadPRE,
                                       bool disableVectorization,
                                       std::string& errMsg) {
  // make unique temp .o file to put generated object file
  SmallString<128> Filename;
  int FD;
  std::error_code EC =
      sys::fs::createTemporaryFile("lto-llvm", "o", FD, Filename);
  if (EC) {
    errMsg = EC.message();
    return false;
  }

  // generate object file
  tool_output_file objFile(Filename.c_str(), FD);

  bool genResult =
      generateObjectFile(objFile.os(), disableOpt, disableInline,
                         disableGVNLoadPRE, disableVectorization, errMsg);
  objFile.os().close();
  if (objFile.os().has_error()) {
    objFile.os().clear_error();
    sys::fs::remove(Twine(Filename));
    return false;
  }

  objFile.keep();
  if (!genResult) {
    sys::fs::remove(Twine(Filename));
    return false;
  }

  NativeObjectPath = Filename.c_str();
  *name = NativeObjectPath.c_str();
  return true;
}

const void* LTOCodeGenerator::compile(size_t* length,
                                      bool disableOpt,
                                      bool disableInline,
                                      bool disableGVNLoadPRE,
                                      bool disableVectorization,
                                      std::string& errMsg) {
  const char *name;
  if (!compile_to_file(&name, disableOpt, disableInline, disableGVNLoadPRE,
                       disableVectorization, errMsg))
    return nullptr;

  // read .o file into memory buffer
  ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
      MemoryBuffer::getFile(name, -1, false);
  if (std::error_code EC = BufferOrErr.getError()) {
    errMsg = EC.message();
    sys::fs::remove(NativeObjectPath);
    return nullptr;
  }
  NativeObjectFile = std::move(*BufferOrErr);

  // remove temp files
  sys::fs::remove(NativeObjectPath);

  // return buffer, unless error
  if (!NativeObjectFile)
    return nullptr;
  *length = NativeObjectFile->getBufferSize();
  return NativeObjectFile->getBufferStart();
}

bool LTOCodeGenerator::determineTarget(std::string &errMsg) {
  if (TargetMach)
    return true;

  std::string TripleStr = IRLinker.getModule()->getTargetTriple();
  if (TripleStr.empty())
    TripleStr = sys::getDefaultTargetTriple();
  llvm::Triple Triple(TripleStr);

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

  // 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;
  case LTO_CODEGEN_PIC_MODEL_DEFAULT:
    // RelocModel is already the default, so leave it that way.
    break;
  }

  // Construct LTOModule, hand over ownership of module and target. Use MAttr as
  // the default set of features.
  SubtargetFeatures Features(MAttr);
  Features.getDefaultSubtargetFeatures(Triple);
  std::string FeatureStr = Features.getString();
  // Set a default CPU for Darwin triples.
  if (MCpu.empty() && Triple.isOSDarwin()) {
    if (Triple.getArch() == llvm::Triple::x86_64)
      MCpu = "core2";
    else if (Triple.getArch() == llvm::Triple::x86)
      MCpu = "yonah";
    else if (Triple.getArch() == llvm::Triple::aarch64)
      MCpu = "cyclone";
  }

  TargetMach = march->createTargetMachine(TripleStr, MCpu, FeatureStr, Options,
                                          RelocModel, CodeModel::Default,
                                          CodeGenOpt::Aggressive);
  return true;
}

void LTOCodeGenerator::
applyRestriction(GlobalValue &GV,
                 ArrayRef<StringRef> Libcalls,
                 std::vector<const char*> &MustPreserveList,
                 SmallPtrSetImpl<GlobalValue*> &AsmUsed,
                 Mangler &Mangler) {
  // There are no restrictions to apply to declarations.
  if (GV.isDeclaration())
    return;

  // There is nothing more restrictive than private linkage.
  if (GV.hasPrivateLinkage())
    return;

  SmallString<64> Buffer;
  TargetMach->getNameWithPrefix(Buffer, &GV, Mangler);

  if (MustPreserveSymbols.count(Buffer))
    MustPreserveList.push_back(GV.getName().data());
  if (AsmUndefinedRefs.count(Buffer))
    AsmUsed.insert(&GV);

  // Conservatively append user-supplied runtime library functions to
  // llvm.compiler.used.  These could be internalized and deleted by
  // optimizations like -globalopt, causing problems when later optimizations
  // add new library calls (e.g., llvm.memset => memset and printf => puts).
  // Leave it to the linker to remove any dead code (e.g. with -dead_strip).
  if (isa<Function>(GV) &&
      std::binary_search(Libcalls.begin(), Libcalls.end(), GV.getName()))
    AsmUsed.insert(&GV);
}

static void findUsedValues(GlobalVariable *LLVMUsed,
                           SmallPtrSetImpl<GlobalValue*> &UsedValues) {
  if (!LLVMUsed) return;

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

static void accumulateAndSortLibcalls(std::vector<StringRef> &Libcalls,
                                      const TargetLibraryInfo& TLI,
                                      const TargetLowering *Lowering)
{
  // TargetLibraryInfo has info on C runtime library calls on the current
  // target.
  for (unsigned I = 0, E = static_cast<unsigned>(LibFunc::NumLibFuncs);
       I != E; ++I) {
    LibFunc::Func F = static_cast<LibFunc::Func>(I);
    if (TLI.has(F))
      Libcalls.push_back(TLI.getName(F));
  }

  // TargetLowering has info on library calls that CodeGen expects to be
  // available, both from the C runtime and compiler-rt.
  if (Lowering)
    for (unsigned I = 0, E = static_cast<unsigned>(RTLIB::UNKNOWN_LIBCALL);
         I != E; ++I)
      if (const char *Name
          = Lowering->getLibcallName(static_cast<RTLIB::Libcall>(I)))
        Libcalls.push_back(Name);

  array_pod_sort(Libcalls.begin(), Libcalls.end());
  Libcalls.erase(std::unique(Libcalls.begin(), Libcalls.end()),
                 Libcalls.end());
}

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

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

  // mark which symbols can not be internalized
  Mangler Mangler(TargetMach->getSubtargetImpl()->getDataLayout());
  std::vector<const char*> MustPreserveList;
  SmallPtrSet<GlobalValue*, 8> AsmUsed;
  std::vector<StringRef> Libcalls;
  TargetLibraryInfo TLI(Triple(TargetMach->getTargetTriple()));
  accumulateAndSortLibcalls(
      Libcalls, TLI, TargetMach->getSubtargetImpl()->getTargetLowering());

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

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

  if (!AsmUsed.empty()) {
    llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(Context);
    std::vector<Constant*> asmUsed2;
    for (auto *GV : AsmUsed) {
      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,
                                          bool DisableOpt,
                                          bool DisableInline,
                                          bool DisableGVNLoadPRE,
                                          bool DisableVectorization,
                                          std::string &errMsg) {
  if (!this->determineTarget(errMsg))
    return false;

  Module *mergedModule = IRLinker.getModule();

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

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

  // Add an appropriate DataLayout instance for this module...
  mergedModule->setDataLayout(TargetMach->getSubtargetImpl()->getDataLayout());

  Triple TargetTriple(TargetMach->getTargetTriple());
  PassManagerBuilder PMB;
  PMB.DisableGVNLoadPRE = DisableGVNLoadPRE;
  PMB.LoopVectorize = !DisableVectorization;
  PMB.SLPVectorize = !DisableVectorization;
  if (!DisableInline)
    PMB.Inliner = createFunctionInliningPass();
  PMB.LibraryInfo = new TargetLibraryInfo(TargetTriple);
  if (DisableOpt)
    PMB.OptLevel = 0;
  PMB.VerifyInput = true;
  PMB.VerifyOutput = true;

  PMB.populateLTOPassManager(passes, TargetMach);

  PassManager codeGenPasses;

  codeGenPasses.add(new DataLayoutPass());

  formatted_raw_ostream Out(out);

  // If the bitcode files contain ARC code and were compiled with optimization,
  // the ObjCARCContractPass must be run, so do it unconditionally here.
  codeGenPasses.add(createObjCARCContractPass());

  if (TargetMach->addPassesToEmitFile(codeGenPasses, Out,
                                      TargetMachine::CGFT_ObjectFile)) {
    errMsg = "target file type not supported";
    return false;
  }

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

  // Run the code generator, and write assembly file
  codeGenPasses.run(*mergedModule);

  return true;
}

/// 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("libLLVMLTO"));
    CodegenOptions.push_back(strdup(o.first.str().c_str()));
  }
}

void LTOCodeGenerator::parseCodeGenDebugOptions() {
  // if options were requested, set them
  if (!CodegenOptions.empty())
    cl::ParseCommandLineOptions(CodegenOptions.size(),
                                const_cast<char **>(&CodegenOptions[0]));
}

void LTOCodeGenerator::DiagnosticHandler(const DiagnosticInfo &DI,
                                         void *Context) {
  ((LTOCodeGenerator *)Context)->DiagnosticHandler2(DI);
}

void LTOCodeGenerator::DiagnosticHandler2(const DiagnosticInfo &DI) {
  // Map the LLVM internal diagnostic severity to the LTO diagnostic severity.
  lto_codegen_diagnostic_severity_t Severity;
  switch (DI.getSeverity()) {
  case DS_Error:
    Severity = LTO_DS_ERROR;
    break;
  case DS_Warning:
    Severity = LTO_DS_WARNING;
    break;
  case DS_Remark:
    Severity = LTO_DS_REMARK;
    break;
  case DS_Note:
    Severity = LTO_DS_NOTE;
    break;
  }
  // Create the string that will be reported to the external diagnostic handler.
  std::string MsgStorage;
  raw_string_ostream Stream(MsgStorage);
  DiagnosticPrinterRawOStream DP(Stream);
  DI.print(DP);
  Stream.flush();

  // If this method has been called it means someone has set up an external
  // diagnostic handler. Assert on that.
  assert(DiagHandler && "Invalid diagnostic handler");
  (*DiagHandler)(Severity, MsgStorage.c_str(), DiagContext);
}

void
LTOCodeGenerator::setDiagnosticHandler(lto_diagnostic_handler_t DiagHandler,
                                       void *Ctxt) {
  this->DiagHandler = DiagHandler;
  this->DiagContext = Ctxt;
  if (!DiagHandler)
    return Context.setDiagnosticHandler(nullptr, nullptr);
  // Register the LTOCodeGenerator stub in the LLVMContext to forward the
  // diagnostic to the external DiagHandler.
  Context.setDiagnosticHandler(LTOCodeGenerator::DiagnosticHandler, this,
                               /* RespectFilters */ true);
}