summaryrefslogtreecommitdiff
path: root/tools/gold/gold-plugin.cpp
blob: e194038b7d83f027b5cb4566c954f7a214105f01 (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
//===-- gold-plugin.cpp - Plugin to gold for Link Time Optimization  ------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This is a gold plugin for LLVM. It provides an LLVM implementation of the
// interface described in http://gcc.gnu.org/wiki/whopr/driver .
//
//===----------------------------------------------------------------------===//

#include "llvm/Config/config.h" // plugin-api.h requires HAVE_STDINT_H
#include "llvm-c/lto.h"
#include "llvm/ADT/OwningPtr.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/Support/Errno.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Program.h"
#include "llvm/Support/ToolOutputFile.h"
#include "llvm/Support/system_error.h"
#include <cerrno>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <list>
#include <plugin-api.h>
#include <vector>

// Support Windows/MinGW crazyness.
#ifdef _WIN32
# include <io.h>
# define lseek _lseek
# define read _read
#endif

using namespace llvm;

namespace {
  ld_plugin_status discard_message(int level, const char *format, ...) {
    // Die loudly. Recent versions of Gold pass ld_plugin_message as the first
    // callback in the transfer vector. This should never be called.
    abort();
  }

  ld_plugin_add_symbols add_symbols = NULL;
  ld_plugin_get_symbols get_symbols = NULL;
  ld_plugin_add_input_file add_input_file = NULL;
  ld_plugin_add_input_library add_input_library = NULL;
  ld_plugin_set_extra_library_path set_extra_library_path = NULL;
  ld_plugin_get_view get_view = NULL;
  ld_plugin_message message = discard_message;

  int api_version = 0;
  int gold_version = 0;

  struct claimed_file {
    void *handle;
    std::vector<ld_plugin_symbol> syms;
  };

  lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
  std::string output_name = "";
  std::list<claimed_file> Modules;
  std::vector<std::string> Cleanup;
  lto_code_gen_t code_gen = NULL;
  StringSet<> CannotBeHidden;
}

namespace options {
  enum generate_bc { BC_NO, BC_ALSO, BC_ONLY };
  static bool generate_api_file = false;
  static generate_bc generate_bc_file = BC_NO;
  static std::string bc_path;
  static std::string obj_path;
  static std::string extra_library_path;
  static std::string triple;
  static std::string mcpu;
  // Additional options to pass into the code generator.
  // Note: This array will contain all plugin options which are not claimed
  // as plugin exclusive to pass to the code generator.
  // For example, "generate-api-file" and "as"options are for the plugin
  // use only and will not be passed.
  static std::vector<std::string> extra;

  static void process_plugin_option(const char* opt_)
  {
    if (opt_ == NULL)
      return;
    llvm::StringRef opt = opt_;

    if (opt == "generate-api-file") {
      generate_api_file = true;
    } else if (opt.startswith("mcpu=")) {
      mcpu = opt.substr(strlen("mcpu="));
    } else if (opt.startswith("extra-library-path=")) {
      extra_library_path = opt.substr(strlen("extra_library_path="));
    } else if (opt.startswith("mtriple=")) {
      triple = opt.substr(strlen("mtriple="));
    } else if (opt.startswith("obj-path=")) {
      obj_path = opt.substr(strlen("obj-path="));
    } else if (opt == "emit-llvm") {
      generate_bc_file = BC_ONLY;
    } else if (opt == "also-emit-llvm") {
      generate_bc_file = BC_ALSO;
    } else if (opt.startswith("also-emit-llvm=")) {
      llvm::StringRef path = opt.substr(strlen("also-emit-llvm="));
      generate_bc_file = BC_ALSO;
      if (!bc_path.empty()) {
        (*message)(LDPL_WARNING, "Path to the output IL file specified twice. "
                   "Discarding %s", opt_);
      } else {
        bc_path = path;
      }
    } else {
      // Save this option to pass to the code generator.
      extra.push_back(opt);
    }
  }
}

static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
                                        int *claimed);
static ld_plugin_status all_symbols_read_hook(void);
static ld_plugin_status cleanup_hook(void);

extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
ld_plugin_status onload(ld_plugin_tv *tv) {
  // We're given a pointer to the first transfer vector. We read through them
  // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
  // contain pointers to functions that we need to call to register our own
  // hooks. The others are addresses of functions we can use to call into gold
  // for services.

  bool registeredClaimFile = false;

  for (; tv->tv_tag != LDPT_NULL; ++tv) {
    switch (tv->tv_tag) {
      case LDPT_API_VERSION:
        api_version = tv->tv_u.tv_val;
        break;
      case LDPT_GOLD_VERSION:  // major * 100 + minor
        gold_version = tv->tv_u.tv_val;
        break;
      case LDPT_OUTPUT_NAME:
        output_name = tv->tv_u.tv_string;
        break;
      case LDPT_LINKER_OUTPUT:
        switch (tv->tv_u.tv_val) {
          case LDPO_REL:  // .o
          case LDPO_DYN:  // .so
          // FIXME: Replace 3 with LDPO_PIE once that is in a released binutils.
          case 3: // position independent executable
            output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
            break;
          case LDPO_EXEC:  // .exe
            output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
            break;
          default:
            (*message)(LDPL_ERROR, "Unknown output file type %d",
                       tv->tv_u.tv_val);
            return LDPS_ERR;
        }
        // TODO: add an option to disable PIC.
        //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
        break;
      case LDPT_OPTION:
        options::process_plugin_option(tv->tv_u.tv_string);
        break;
      case LDPT_REGISTER_CLAIM_FILE_HOOK: {
        ld_plugin_register_claim_file callback;
        callback = tv->tv_u.tv_register_claim_file;

        if ((*callback)(claim_file_hook) != LDPS_OK)
          return LDPS_ERR;

        registeredClaimFile = true;
      } break;
      case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
        ld_plugin_register_all_symbols_read callback;
        callback = tv->tv_u.tv_register_all_symbols_read;

        if ((*callback)(all_symbols_read_hook) != LDPS_OK)
          return LDPS_ERR;

        code_gen = lto_codegen_create();
      } break;
      case LDPT_REGISTER_CLEANUP_HOOK: {
        ld_plugin_register_cleanup callback;
        callback = tv->tv_u.tv_register_cleanup;

        if ((*callback)(cleanup_hook) != LDPS_OK)
          return LDPS_ERR;
      } break;
      case LDPT_ADD_SYMBOLS:
        add_symbols = tv->tv_u.tv_add_symbols;
        break;
      case LDPT_GET_SYMBOLS_V2:
        get_symbols = tv->tv_u.tv_get_symbols;
        break;
      case LDPT_ADD_INPUT_FILE:
        add_input_file = tv->tv_u.tv_add_input_file;
        break;
      case LDPT_ADD_INPUT_LIBRARY:
        add_input_library = tv->tv_u.tv_add_input_file;
        break;
      case LDPT_SET_EXTRA_LIBRARY_PATH:
        set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
        break;
      case LDPT_GET_VIEW:
        get_view = tv->tv_u.tv_get_view;
        break;
      case LDPT_MESSAGE:
        message = tv->tv_u.tv_message;
        break;
      default:
        break;
    }
  }

  if (!registeredClaimFile) {
    (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
    return LDPS_ERR;
  }
  if (!add_symbols) {
    (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
    return LDPS_ERR;
  }

  return LDPS_OK;
}

/// claim_file_hook - called by gold to see whether this file is one that
/// our plugin can handle. We'll try to open it and register all the symbols
/// with add_symbol if possible.
static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
                                        int *claimed) {
  lto_module_t M;
  const void *view;
  OwningPtr<MemoryBuffer> buffer;
  if (get_view) {
    if (get_view(file->handle, &view) != LDPS_OK) {
      (*message)(LDPL_ERROR, "Failed to get a view of %s", file->name);
      return LDPS_ERR;
    }
  } else {
    int64_t offset = 0;
    // Gold has found what might be IR part-way inside of a file, such as
    // an .a archive.
    if (file->offset) {
      offset = file->offset;
    }
    if (error_code ec = MemoryBuffer::getOpenFileSlice(
            file->fd, file->name, buffer, file->filesize, offset)) {
      (*message)(LDPL_ERROR, ec.message().c_str());
      return LDPS_ERR;
    }
    view = buffer->getBufferStart();
  }

  if (!lto_module_is_object_file_in_memory(view, file->filesize))
    return LDPS_OK;

  M = lto_module_create_from_memory(view, file->filesize);
  if (!M) {
    if (const char* msg = lto_get_error_message()) {
      (*message)(LDPL_ERROR,
                 "LLVM gold plugin has failed to create LTO module: %s",
                 msg);
      return LDPS_ERR;
    }
    return LDPS_OK;
  }

  *claimed = 1;
  Modules.resize(Modules.size() + 1);
  claimed_file &cf = Modules.back();

  if (!options::triple.empty())
    lto_module_set_target_triple(M, options::triple.c_str());

  cf.handle = file->handle;
  unsigned sym_count = lto_module_get_num_symbols(M);
  cf.syms.reserve(sym_count);

  for (unsigned i = 0; i != sym_count; ++i) {
    lto_symbol_attributes attrs = lto_module_get_symbol_attribute(M, i);
    if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
      continue;

    cf.syms.push_back(ld_plugin_symbol());
    ld_plugin_symbol &sym = cf.syms.back();
    sym.name = const_cast<char *>(lto_module_get_symbol_name(M, i));
    sym.name = strdup(sym.name);
    sym.version = NULL;

    int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
    bool CanBeHidden = scope == LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN;
    if (!CanBeHidden)
      CannotBeHidden.insert(sym.name);
    switch (scope) {
      case LTO_SYMBOL_SCOPE_HIDDEN:
        sym.visibility = LDPV_HIDDEN;
        break;
      case LTO_SYMBOL_SCOPE_PROTECTED:
        sym.visibility = LDPV_PROTECTED;
        break;
      case 0: // extern
      case LTO_SYMBOL_SCOPE_DEFAULT:
      case LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN:
        sym.visibility = LDPV_DEFAULT;
        break;
      default:
        (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
        return LDPS_ERR;
    }

    int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
    sym.comdat_key = NULL;
    switch (definition) {
      case LTO_SYMBOL_DEFINITION_REGULAR:
        sym.def = LDPK_DEF;
        break;
      case LTO_SYMBOL_DEFINITION_UNDEFINED:
        sym.def = LDPK_UNDEF;
        break;
      case LTO_SYMBOL_DEFINITION_TENTATIVE:
        sym.def = LDPK_COMMON;
        break;
      case LTO_SYMBOL_DEFINITION_WEAK:
        sym.comdat_key = sym.name;
        sym.def = LDPK_WEAKDEF;
        break;
      case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
        sym.def = LDPK_WEAKUNDEF;
        break;
      default:
        (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
        return LDPS_ERR;
    }

    sym.size = 0;

    sym.resolution = LDPR_UNKNOWN;
  }

  cf.syms.reserve(cf.syms.size());

  if (!cf.syms.empty()) {
    if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
      (*message)(LDPL_ERROR, "Unable to add symbols!");
      return LDPS_ERR;
    }
  }

  if (code_gen) {
    if (lto_codegen_add_module(code_gen, M)) {
      (*message)(LDPL_ERROR, "Error linking module: %s",
                 lto_get_error_message());
      return LDPS_ERR;
    }
  }

  lto_module_dispose(M);

  return LDPS_OK;
}

static bool mustPreserve(const claimed_file &F, int i) {
  if (F.syms[i].resolution == LDPR_PREVAILING_DEF)
    return true;
  if (F.syms[i].resolution == LDPR_PREVAILING_DEF_IRONLY_EXP)
    return CannotBeHidden.count(F.syms[i].name);
  return false;
}

/// all_symbols_read_hook - gold informs us that all symbols have been read.
/// At this point, we use get_symbols to see if any of our definitions have
/// been overridden by a native object file. Then, perform optimization and
/// codegen.
static ld_plugin_status all_symbols_read_hook(void) {
  std::ofstream api_file;
  assert(code_gen);

  if (options::generate_api_file) {
    api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
    if (!api_file.is_open()) {
      (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
      abort();
    }
  }

  for (std::list<claimed_file>::iterator I = Modules.begin(),
         E = Modules.end(); I != E; ++I) {
    if (I->syms.empty())
      continue;
    (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
    for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
      if (mustPreserve(*I, i)) {
        lto_codegen_add_must_preserve_symbol(code_gen, I->syms[i].name);

        if (options::generate_api_file)
          api_file << I->syms[i].name << "\n";
      }
    }
  }

  if (options::generate_api_file)
    api_file.close();

  lto_codegen_set_pic_model(code_gen, output_type);
  lto_codegen_set_debug_model(code_gen, LTO_DEBUG_MODEL_DWARF);
  if (!options::mcpu.empty())
    lto_codegen_set_cpu(code_gen, options::mcpu.c_str());

  // Pass through extra options to the code generator.
  if (!options::extra.empty()) {
    for (std::vector<std::string>::iterator it = options::extra.begin();
         it != options::extra.end(); ++it) {
      lto_codegen_debug_options(code_gen, (*it).c_str());
    }
  }

  if (options::generate_bc_file != options::BC_NO) {
    std::string path;
    if (options::generate_bc_file == options::BC_ONLY)
      path = output_name;
    else if (!options::bc_path.empty())
      path = options::bc_path;
    else
      path = output_name + ".bc";
    bool err = lto_codegen_write_merged_modules(code_gen, path.c_str());
    if (err)
      (*message)(LDPL_FATAL, "Failed to write the output file.");
    if (options::generate_bc_file == options::BC_ONLY) {
      lto_codegen_dispose(code_gen);
      exit(0);
    }
  }

  std::string ObjPath;
  {
    const char *Temp;
    if (lto_codegen_compile_to_file(code_gen, &Temp)) {
      (*message)(LDPL_ERROR, "Could not produce a combined object file\n");
    }
    ObjPath = Temp;
  }

  lto_codegen_dispose(code_gen);
  for (std::list<claimed_file>::iterator I = Modules.begin(),
         E = Modules.end(); I != E; ++I) {
    for (unsigned i = 0; i != I->syms.size(); ++i) {
      ld_plugin_symbol &sym = I->syms[i];
      free(sym.name);
    }
  }

  if ((*add_input_file)(ObjPath.c_str()) != LDPS_OK) {
    (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
    (*message)(LDPL_ERROR, "File left behind in: %s", ObjPath.c_str());
    return LDPS_ERR;
  }

  if (!options::extra_library_path.empty() &&
      set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) {
    (*message)(LDPL_ERROR, "Unable to set the extra library path.");
    return LDPS_ERR;
  }

  if (options::obj_path.empty())
    Cleanup.push_back(ObjPath);

  return LDPS_OK;
}

static ld_plugin_status cleanup_hook(void) {
  for (int i = 0, e = Cleanup.size(); i != e; ++i) {
    error_code EC = sys::fs::remove(Cleanup[i]);
    if (EC)
      (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),
                 EC.message().c_str());
  }

  return LDPS_OK;
}