llvm.org GIT mirror llvm / release_28 tools / lto / LTOModule.cpp
release_28

Tree @release_28 (Download .tar.gz)

LTOModule.cpp @release_28raw · 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
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
//===-- LTOModule.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 "LTOModule.h"

#include "llvm/Constants.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/ADT/OwningPtr.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/Support/SystemUtils.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/System/Host.h"
#include "llvm/System/Path.h"
#include "llvm/System/Process.h"
#include "llvm/Target/Mangler.h"
#include "llvm/Target/SubtargetFeature.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetRegistry.h"
#include "llvm/Target/TargetSelect.h"

using namespace llvm;

bool LTOModule::isBitcodeFile(const void *mem, size_t length) {
  return llvm::sys::IdentifyFileType((char*)mem, length)
    == llvm::sys::Bitcode_FileType;
}

bool LTOModule::isBitcodeFile(const char *path) {
  return llvm::sys::Path(path).isBitcodeFile();
}

bool LTOModule::isBitcodeFileForTarget(const void *mem, size_t length,
                                       const char *triplePrefix) {
  MemoryBuffer *buffer = makeBuffer(mem, length);
  if (!buffer)
    return false;
  return isTargetMatch(buffer, triplePrefix);
}


bool LTOModule::isBitcodeFileForTarget(const char *path,
                                       const char *triplePrefix) {
  MemoryBuffer *buffer = MemoryBuffer::getFile(path);
  if (buffer == NULL)
    return false;
  return isTargetMatch(buffer, triplePrefix);
}

// Takes ownership of buffer.
bool LTOModule::isTargetMatch(MemoryBuffer *buffer, const char *triplePrefix) {
  OwningPtr<Module> m(getLazyBitcodeModule(buffer, getGlobalContext()));
  // On success, m owns buffer and both are deleted at end of this method.
  if (!m) {
    delete buffer;
    return false;
  }
  std::string actualTarget = m->getTargetTriple();
  return (strncmp(actualTarget.c_str(), triplePrefix,
                  strlen(triplePrefix)) == 0);
}


LTOModule::LTOModule(Module *m, TargetMachine *t)
  : _module(m), _target(t), _symbolsParsed(false)
{
}

LTOModule *LTOModule::makeLTOModule(const char *path,
                                    std::string &errMsg) {
  OwningPtr<MemoryBuffer> buffer(MemoryBuffer::getFile(path, &errMsg));
  if (!buffer)
    return NULL;
  return makeLTOModule(buffer.get(), errMsg);
}

/// makeBuffer - Create a MemoryBuffer from a memory range.  MemoryBuffer
/// requires the byte past end of the buffer to be a zero.  We might get lucky
/// and already be that way, otherwise make a copy.  Also if next byte is on a
/// different page, don't assume it is readable.
MemoryBuffer *LTOModule::makeBuffer(const void *mem, size_t length) {
  const char *startPtr = (char*)mem;
  const char *endPtr = startPtr+length;
  if (((uintptr_t)endPtr & (sys::Process::GetPageSize()-1)) == 0 ||
      *endPtr != 0)
    return MemoryBuffer::getMemBufferCopy(StringRef(startPtr, length));

  return MemoryBuffer::getMemBuffer(StringRef(startPtr, length));
}


LTOModule *LTOModule::makeLTOModule(const void *mem, size_t length,
                                    std::string &errMsg) {
  OwningPtr<MemoryBuffer> buffer(makeBuffer(mem, length));
  if (!buffer)
    return NULL;
  return makeLTOModule(buffer.get(), errMsg);
}

LTOModule *LTOModule::makeLTOModule(MemoryBuffer *buffer,
                                    std::string &errMsg) {
  InitializeAllTargets();

  // parse bitcode buffer
  OwningPtr<Module> m(ParseBitcodeFile(buffer, getGlobalContext(), &errMsg));
  if (!m)
    return NULL;

  std::string Triple = m->getTargetTriple();
  if (Triple.empty())
    Triple = sys::getHostTriple();

  // find machine architecture for this module
  const Target *march = TargetRegistry::lookupTarget(Triple, errMsg);
  if (!march)
    return NULL;

  // construct LTModule, hand over ownership of module and target
  SubtargetFeatures Features;
  Features.getDefaultSubtargetFeatures("" /* cpu */, llvm::Triple(Triple));
  std::string FeatureStr = Features.getString();
  TargetMachine *target = march->createTargetMachine(Triple, FeatureStr);
  return new LTOModule(m.take(), target);
}


const char *LTOModule::getTargetTriple() {
  return _module->getTargetTriple().c_str();
}

void LTOModule::setTargetTriple(const char *triple) {
  _module->setTargetTriple(triple);
}

void LTOModule::addDefinedFunctionSymbol(Function *f, Mangler &mangler) {
  // add to list of defined symbols
  addDefinedSymbol(f, mangler, true);

  // add external symbols referenced by this function.
  for (Function::iterator b = f->begin(); b != f->end(); ++b) {
    for (BasicBlock::iterator i = b->begin(); i != b->end(); ++i) {
      for (unsigned count = 0, total = i->getNumOperands();
           count != total; ++count) {
        findExternalRefs(i->getOperand(count), mangler);
      }
    }
  }
}

// Get string that data pointer points to.
bool LTOModule::objcClassNameFromExpression(Constant *c, std::string &name) {
  if (ConstantExpr *ce = dyn_cast<ConstantExpr>(c)) {
    Constant *op = ce->getOperand(0);
    if (GlobalVariable *gvn = dyn_cast<GlobalVariable>(op)) {
      Constant *cn = gvn->getInitializer();
      if (ConstantArray *ca = dyn_cast<ConstantArray>(cn)) {
        if (ca->isCString()) {
          name = ".objc_class_name_" + ca->getAsString();
          return true;
        }
      }
    }
  }
  return false;
}

// Parse i386/ppc ObjC class data structure.
void LTOModule::addObjCClass(GlobalVariable *clgv) {
  if (ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer())) {
    // second slot in __OBJC,__class is pointer to superclass name
    std::string superclassName;
    if (objcClassNameFromExpression(c->getOperand(1), superclassName)) {
      NameAndAttributes info;
      if (_undefines.find(superclassName.c_str()) == _undefines.end()) {
        const char *symbolName = ::strdup(superclassName.c_str());
        info.name = symbolName;
        info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
        // string is owned by _undefines
        _undefines[info.name] = info;
      }
    }
    // third slot in __OBJC,__class is pointer to class name
    std::string className;
    if (objcClassNameFromExpression(c->getOperand(2), className)) {
      const char *symbolName = ::strdup(className.c_str());
      NameAndAttributes info;
      info.name = symbolName;
      info.attributes = (lto_symbol_attributes)
        (LTO_SYMBOL_PERMISSIONS_DATA |
         LTO_SYMBOL_DEFINITION_REGULAR |
         LTO_SYMBOL_SCOPE_DEFAULT);
      _symbols.push_back(info);
      _defines[info.name] = 1;
    }
  }
}


// Parse i386/ppc ObjC category data structure.
void LTOModule::addObjCCategory(GlobalVariable *clgv) {
  if (ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer())) {
    // second slot in __OBJC,__category is pointer to target class name
    std::string targetclassName;
    if (objcClassNameFromExpression(c->getOperand(1), targetclassName)) {
      NameAndAttributes info;
      if (_undefines.find(targetclassName.c_str()) == _undefines.end()) {
        const char *symbolName = ::strdup(targetclassName.c_str());
        info.name = symbolName;
        info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
        // string is owned by _undefines
        _undefines[info.name] = info;
      }
    }
  }
}


// Parse i386/ppc ObjC class list data structure.
void LTOModule::addObjCClassRef(GlobalVariable *clgv) {
  std::string targetclassName;
  if (objcClassNameFromExpression(clgv->getInitializer(), targetclassName)) {
    NameAndAttributes info;
    if (_undefines.find(targetclassName.c_str()) == _undefines.end()) {
      const char *symbolName = ::strdup(targetclassName.c_str());
      info.name = symbolName;
      info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
      // string is owned by _undefines
      _undefines[info.name] = info;
    }
  }
}


void LTOModule::addDefinedDataSymbol(GlobalValue *v, Mangler &mangler) {
  // Add to list of defined symbols.
  addDefinedSymbol(v, mangler, false);

  // Special case i386/ppc ObjC data structures in magic sections:
  // The issue is that the old ObjC object format did some strange
  // contortions to avoid real linker symbols.  For instance, the
  // ObjC class data structure is allocated statically in the executable
  // that defines that class.  That data structures contains a pointer to
  // its superclass.  But instead of just initializing that part of the
  // struct to the address of its superclass, and letting the static and
  // dynamic linkers do the rest, the runtime works by having that field
  // instead point to a C-string that is the name of the superclass.
  // At runtime the objc initialization updates that pointer and sets
  // it to point to the actual super class.  As far as the linker
  // knows it is just a pointer to a string.  But then someone wanted the
  // linker to issue errors at build time if the superclass was not found.
  // So they figured out a way in mach-o object format to use an absolute
  // symbols (.objc_class_name_Foo = 0) and a floating reference
  // (.reference .objc_class_name_Bar) to cause the linker into erroring when
  // a class was missing.
  // The following synthesizes the implicit .objc_* symbols for the linker
  // from the ObjC data structures generated by the front end.
  if (v->hasSection() /* && isTargetDarwin */) {
    // special case if this data blob is an ObjC class definition
    if (v->getSection().compare(0, 15, "__OBJC,__class,") == 0) {
      if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
        addObjCClass(gv);
      }
    }

    // special case if this data blob is an ObjC category definition
    else if (v->getSection().compare(0, 18, "__OBJC,__category,") == 0) {
      if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
        addObjCCategory(gv);
      }
    }

    // special case if this data blob is the list of referenced classes
    else if (v->getSection().compare(0, 18, "__OBJC,__cls_refs,") == 0) {
      if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
        addObjCClassRef(gv);
      }
    }
  }

  // add external symbols referenced by this data.
  for (unsigned count = 0, total = v->getNumOperands();
       count != total; ++count) {
    findExternalRefs(v->getOperand(count), mangler);
  }
}


void LTOModule::addDefinedSymbol(GlobalValue *def, Mangler &mangler,
                                 bool isFunction) {
  // ignore all llvm.* symbols
  if (def->getName().startswith("llvm."))
    return;

  // string is owned by _defines
  const char *symbolName = ::strdup(mangler.getNameWithPrefix(def).c_str());

  // set alignment part log2() can have rounding errors
  uint32_t align = def->getAlignment();
  uint32_t attr = align ? CountTrailingZeros_32(def->getAlignment()) : 0;

  // set permissions part
  if (isFunction)
    attr |= LTO_SYMBOL_PERMISSIONS_CODE;
  else {
    GlobalVariable *gv = dyn_cast<GlobalVariable>(def);
    if (gv && gv->isConstant())
      attr |= LTO_SYMBOL_PERMISSIONS_RODATA;
    else
      attr |= LTO_SYMBOL_PERMISSIONS_DATA;
  }

  // set definition part
  if (def->hasWeakLinkage() || def->hasLinkOnceLinkage()) {
    attr |= LTO_SYMBOL_DEFINITION_WEAK;
  }
  else if (def->hasCommonLinkage()) {
    attr |= LTO_SYMBOL_DEFINITION_TENTATIVE;
  }
  else {
    attr |= LTO_SYMBOL_DEFINITION_REGULAR;
  }

  // set scope part
  if (def->hasHiddenVisibility())
    attr |= LTO_SYMBOL_SCOPE_HIDDEN;
  else if (def->hasProtectedVisibility())
    attr |= LTO_SYMBOL_SCOPE_PROTECTED;
  else if (def->hasExternalLinkage() || def->hasWeakLinkage()
           || def->hasLinkOnceLinkage() || def->hasCommonLinkage())
    attr |= LTO_SYMBOL_SCOPE_DEFAULT;
  else
    attr |= LTO_SYMBOL_SCOPE_INTERNAL;

  // add to table of symbols
  NameAndAttributes info;
  info.name = symbolName;
  info.attributes = (lto_symbol_attributes)attr;
  _symbols.push_back(info);
  _defines[info.name] = 1;
}

void LTOModule::addAsmGlobalSymbol(const char *name) {
  // only add new define if not already defined
  if (_defines.count(name))
    return;

  // string is owned by _defines
  const char *symbolName = ::strdup(name);
  uint32_t attr = LTO_SYMBOL_DEFINITION_REGULAR;
  attr |= LTO_SYMBOL_SCOPE_DEFAULT;
  NameAndAttributes info;
  info.name = symbolName;
  info.attributes = (lto_symbol_attributes)attr;
  _symbols.push_back(info);
  _defines[info.name] = 1;
}

void LTOModule::addPotentialUndefinedSymbol(GlobalValue *decl,
                                            Mangler &mangler) {
  // ignore all llvm.* symbols
  if (decl->getName().startswith("llvm."))
    return;

  // ignore all aliases
  if (isa<GlobalAlias>(decl))
    return;

  std::string name = mangler.getNameWithPrefix(decl);

  // we already have the symbol
  if (_undefines.find(name) != _undefines.end())
    return;

  NameAndAttributes info;
  // string is owned by _undefines
  info.name = ::strdup(name.c_str());
  if (decl->hasExternalWeakLinkage())
    info.attributes = LTO_SYMBOL_DEFINITION_WEAKUNDEF;
  else
    info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
  _undefines[name] = info;
}



// Find external symbols referenced by VALUE. This is a recursive function.
void LTOModule::findExternalRefs(Value *value, Mangler &mangler) {
  if (GlobalValue *gv = dyn_cast<GlobalValue>(value)) {
    if (!gv->hasExternalLinkage())
      addPotentialUndefinedSymbol(gv, mangler);
    // If this is a variable definition, do not recursively process
    // initializer.  It might contain a reference to this variable
    // and cause an infinite loop.  The initializer will be
    // processed in addDefinedDataSymbol().
    return;
  }

  // GlobalValue, even with InternalLinkage type, may have operands with
  // ExternalLinkage type. Do not ignore these operands.
  if (Constant *c = dyn_cast<Constant>(value)) {
    // Handle ConstantExpr, ConstantStruct, ConstantArry etc.
    for (unsigned i = 0, e = c->getNumOperands(); i != e; ++i)
      findExternalRefs(c->getOperand(i), mangler);
  }
}

void LTOModule::lazyParseSymbols() {
  if (_symbolsParsed)
    return;

  _symbolsParsed = true;

  // Use mangler to add GlobalPrefix to names to match linker names.
  MCContext Context(*_target->getMCAsmInfo());
  Mangler mangler(Context, *_target->getTargetData());

  // add functions
  for (Module::iterator f = _module->begin(); f != _module->end(); ++f) {
    if (f->isDeclaration())
      addPotentialUndefinedSymbol(f, mangler);
    else
      addDefinedFunctionSymbol(f, mangler);
  }

  // add data
  for (Module::global_iterator v = _module->global_begin(),
         e = _module->global_end(); v !=  e; ++v) {
    if (v->isDeclaration())
      addPotentialUndefinedSymbol(v, mangler);
    else
      addDefinedDataSymbol(v, mangler);
  }

  // add asm globals
  const std::string &inlineAsm = _module->getModuleInlineAsm();
  const std::string glbl = ".globl";
  std::string asmSymbolName;
  std::string::size_type pos = inlineAsm.find(glbl, 0);
  while (pos != std::string::npos) {
    // eat .globl
    pos = pos + 6;

    // skip white space between .globl and symbol name
    std::string::size_type pbegin = inlineAsm.find_first_not_of(' ', pos);
    if (pbegin == std::string::npos)
      break;

    // find end-of-line
    std::string::size_type pend = inlineAsm.find_first_of('\n', pbegin);
    if (pend == std::string::npos)
      break;

    asmSymbolName.assign(inlineAsm, pbegin, pend - pbegin);
    addAsmGlobalSymbol(asmSymbolName.c_str());

    // search next .globl
    pos = inlineAsm.find(glbl, pend);
  }

  // make symbols for all undefines
  for (StringMap<NameAndAttributes>::iterator it=_undefines.begin();
       it != _undefines.end(); ++it) {
    // if this symbol also has a definition, then don't make an undefine
    // because it is a tentative definition
    if (_defines.count(it->getKey()) == 0) {
      NameAndAttributes info = it->getValue();
      _symbols.push_back(info);
    }
  }
}


uint32_t LTOModule::getSymbolCount() {
  lazyParseSymbols();
  return _symbols.size();
}


lto_symbol_attributes LTOModule::getSymbolAttributes(uint32_t index) {
  lazyParseSymbols();
  if (index < _symbols.size())
    return _symbols[index].attributes;
  else
    return lto_symbol_attributes(0);
}

const char *LTOModule::getSymbolName(uint32_t index) {
  lazyParseSymbols();
  if (index < _symbols.size())
    return _symbols[index].name;
  else
    return NULL;
}