1 //===-- gold-plugin.cpp - Plugin to gold for Link Time Optimization ------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This is a gold plugin for LLVM. It provides an LLVM implementation of the 11 // interface described in http://gcc.gnu.org/wiki/whopr/driver . 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "llvm/Config/config.h" 16 #include "plugin-api.h" 17 18 #include "llvm-c/lto.h" 19 20 #include "llvm/ADT/OwningPtr.h" 21 #include "llvm/Support/system_error.h" 22 #include "llvm/Support/MemoryBuffer.h" 23 #include "llvm/Support/ToolOutputFile.h" 24 #include "llvm/Support/Errno.h" 25 #include "llvm/Support/Path.h" 26 #include "llvm/Support/Program.h" 27 28 #include <cerrno> 29 #include <cstdlib> 30 #include <cstring> 31 #include <fstream> 32 #include <list> 33 #include <vector> 34 35 // Support Windows/MinGW crazyness. 36 #ifdef _WIN32 37 # include <io.h> 38 # define lseek _lseek 39 # define read _read 40 #endif 41 42 using namespace llvm; 43 44 namespace { 45 ld_plugin_status discard_message(int level, const char *format, ...) { 46 // Die loudly. Recent versions of Gold pass ld_plugin_message as the first 47 // callback in the transfer vector. This should never be called. 48 abort(); 49 } 50 51 ld_plugin_add_symbols add_symbols = NULL; 52 ld_plugin_get_symbols get_symbols = NULL; 53 ld_plugin_add_input_file add_input_file = NULL; 54 ld_plugin_add_input_library add_input_library = NULL; 55 ld_plugin_set_extra_library_path set_extra_library_path = NULL; 56 ld_plugin_get_view get_view = NULL; 57 ld_plugin_message message = discard_message; 58 59 int api_version = 0; 60 int gold_version = 0; 61 62 struct claimed_file { 63 void *handle; 64 std::vector<ld_plugin_symbol> syms; 65 }; 66 67 lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC; 68 std::string output_name = ""; 69 std::list<claimed_file> Modules; 70 std::vector<sys::Path> Cleanup; 71 lto_code_gen_t code_gen = NULL; 72 } 73 74 namespace options { 75 enum generate_bc { BC_NO, BC_ALSO, BC_ONLY }; 76 static bool generate_api_file = false; 77 static generate_bc generate_bc_file = BC_NO; 78 static std::string bc_path; 79 static std::string obj_path; 80 static std::string extra_library_path; 81 static std::string triple; 82 static std::string mcpu; 83 // Additional options to pass into the code generator. 84 // Note: This array will contain all plugin options which are not claimed 85 // as plugin exclusive to pass to the code generator. 86 // For example, "generate-api-file" and "as"options are for the plugin 87 // use only and will not be passed. 88 static std::vector<std::string> extra; 89 90 static void process_plugin_option(const char* opt_) 91 { 92 if (opt_ == NULL) 93 return; 94 llvm::StringRef opt = opt_; 95 96 if (opt == "generate-api-file") { 97 generate_api_file = true; 98 } else if (opt.startswith("mcpu=")) { 99 mcpu = opt.substr(strlen("mcpu=")); 100 } else if (opt.startswith("extra-library-path=")) { 101 extra_library_path = opt.substr(strlen("extra_library_path=")); 102 } else if (opt.startswith("mtriple=")) { 103 triple = opt.substr(strlen("mtriple=")); 104 } else if (opt.startswith("obj-path=")) { 105 obj_path = opt.substr(strlen("obj-path=")); 106 } else if (opt == "emit-llvm") { 107 generate_bc_file = BC_ONLY; 108 } else if (opt == "also-emit-llvm") { 109 generate_bc_file = BC_ALSO; 110 } else if (opt.startswith("also-emit-llvm=")) { 111 llvm::StringRef path = opt.substr(strlen("also-emit-llvm=")); 112 generate_bc_file = BC_ALSO; 113 if (!bc_path.empty()) { 114 (*message)(LDPL_WARNING, "Path to the output IL file specified twice. " 115 "Discarding %s", opt_); 116 } else { 117 bc_path = path; 118 } 119 } else { 120 // Save this option to pass to the code generator. 121 extra.push_back(opt); 122 } 123 } 124 } 125 126 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file, 127 int *claimed); 128 static ld_plugin_status all_symbols_read_hook(void); 129 static ld_plugin_status cleanup_hook(void); 130 131 extern "C" ld_plugin_status onload(ld_plugin_tv *tv); 132 ld_plugin_status onload(ld_plugin_tv *tv) { 133 // We're given a pointer to the first transfer vector. We read through them 134 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values 135 // contain pointers to functions that we need to call to register our own 136 // hooks. The others are addresses of functions we can use to call into gold 137 // for services. 138 139 bool registeredClaimFile = false; 140 141 for (; tv->tv_tag != LDPT_NULL; ++tv) { 142 switch (tv->tv_tag) { 143 case LDPT_API_VERSION: 144 api_version = tv->tv_u.tv_val; 145 break; 146 case LDPT_GOLD_VERSION: // major * 100 + minor 147 gold_version = tv->tv_u.tv_val; 148 break; 149 case LDPT_OUTPUT_NAME: 150 output_name = tv->tv_u.tv_string; 151 break; 152 case LDPT_LINKER_OUTPUT: 153 switch (tv->tv_u.tv_val) { 154 case LDPO_REL: // .o 155 case LDPO_DYN: // .so 156 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC; 157 break; 158 case LDPO_EXEC: // .exe 159 output_type = LTO_CODEGEN_PIC_MODEL_STATIC; 160 break; 161 default: 162 (*message)(LDPL_ERROR, "Unknown output file type %d", 163 tv->tv_u.tv_val); 164 return LDPS_ERR; 165 } 166 // TODO: add an option to disable PIC. 167 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC; 168 break; 169 case LDPT_OPTION: 170 options::process_plugin_option(tv->tv_u.tv_string); 171 break; 172 case LDPT_REGISTER_CLAIM_FILE_HOOK: { 173 ld_plugin_register_claim_file callback; 174 callback = tv->tv_u.tv_register_claim_file; 175 176 if ((*callback)(claim_file_hook) != LDPS_OK) 177 return LDPS_ERR; 178 179 registeredClaimFile = true; 180 } break; 181 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: { 182 ld_plugin_register_all_symbols_read callback; 183 callback = tv->tv_u.tv_register_all_symbols_read; 184 185 if ((*callback)(all_symbols_read_hook) != LDPS_OK) 186 return LDPS_ERR; 187 188 code_gen = lto_codegen_create(); 189 } break; 190 case LDPT_REGISTER_CLEANUP_HOOK: { 191 ld_plugin_register_cleanup callback; 192 callback = tv->tv_u.tv_register_cleanup; 193 194 if ((*callback)(cleanup_hook) != LDPS_OK) 195 return LDPS_ERR; 196 } break; 197 case LDPT_ADD_SYMBOLS: 198 add_symbols = tv->tv_u.tv_add_symbols; 199 break; 200 case LDPT_GET_SYMBOLS: 201 get_symbols = tv->tv_u.tv_get_symbols; 202 break; 203 case LDPT_ADD_INPUT_FILE: 204 add_input_file = tv->tv_u.tv_add_input_file; 205 break; 206 case LDPT_ADD_INPUT_LIBRARY: 207 add_input_library = tv->tv_u.tv_add_input_file; 208 break; 209 case LDPT_SET_EXTRA_LIBRARY_PATH: 210 set_extra_library_path = tv->tv_u.tv_set_extra_library_path; 211 break; 212 case LDPT_GET_VIEW: 213 get_view = tv->tv_u.tv_get_view; 214 break; 215 case LDPT_MESSAGE: 216 message = tv->tv_u.tv_message; 217 break; 218 default: 219 break; 220 } 221 } 222 223 if (!registeredClaimFile) { 224 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold."); 225 return LDPS_ERR; 226 } 227 if (!add_symbols) { 228 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold."); 229 return LDPS_ERR; 230 } 231 232 return LDPS_OK; 233 } 234 235 /// claim_file_hook - called by gold to see whether this file is one that 236 /// our plugin can handle. We'll try to open it and register all the symbols 237 /// with add_symbol if possible. 238 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file, 239 int *claimed) { 240 lto_module_t M; 241 const void *view; 242 OwningPtr<MemoryBuffer> buffer; 243 if (get_view) { 244 if (get_view(file->handle, &view) != LDPS_OK) { 245 (*message)(LDPL_ERROR, "Failed to get a view of %s", file->name); 246 return LDPS_ERR; 247 } 248 } else { 249 int64_t offset = 0; 250 // Gold has found what might be IR part-way inside of a file, such as 251 // an .a archive. 252 if (file->offset) { 253 offset = file->offset; 254 } 255 if (error_code ec = 256 MemoryBuffer::getOpenFile(file->fd, file->name, buffer, file->filesize, 257 -1, offset, false)) { 258 (*message)(LDPL_ERROR, ec.message().c_str()); 259 return LDPS_ERR; 260 } 261 view = buffer->getBufferStart(); 262 } 263 264 if (!lto_module_is_object_file_in_memory(view, file->filesize)) 265 return LDPS_OK; 266 267 M = lto_module_create_from_memory(view, file->filesize); 268 if (!M) { 269 if (const char* msg = lto_get_error_message()) { 270 (*message)(LDPL_ERROR, 271 "LLVM gold plugin has failed to create LTO module: %s", 272 msg); 273 return LDPS_ERR; 274 } 275 return LDPS_OK; 276 } 277 278 *claimed = 1; 279 Modules.resize(Modules.size() + 1); 280 claimed_file &cf = Modules.back(); 281 282 if (!options::triple.empty()) 283 lto_module_set_target_triple(M, options::triple.c_str()); 284 285 cf.handle = file->handle; 286 unsigned sym_count = lto_module_get_num_symbols(M); 287 cf.syms.reserve(sym_count); 288 289 for (unsigned i = 0; i != sym_count; ++i) { 290 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(M, i); 291 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL) 292 continue; 293 294 cf.syms.push_back(ld_plugin_symbol()); 295 ld_plugin_symbol &sym = cf.syms.back(); 296 sym.name = const_cast<char *>(lto_module_get_symbol_name(M, i)); 297 sym.name = strdup(sym.name); 298 sym.version = NULL; 299 300 int scope = attrs & LTO_SYMBOL_SCOPE_MASK; 301 switch (scope) { 302 case LTO_SYMBOL_SCOPE_HIDDEN: 303 sym.visibility = LDPV_HIDDEN; 304 break; 305 case LTO_SYMBOL_SCOPE_PROTECTED: 306 sym.visibility = LDPV_PROTECTED; 307 break; 308 case 0: // extern 309 case LTO_SYMBOL_SCOPE_DEFAULT: 310 sym.visibility = LDPV_DEFAULT; 311 break; 312 default: 313 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope); 314 return LDPS_ERR; 315 } 316 317 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK; 318 sym.comdat_key = NULL; 319 switch (definition) { 320 case LTO_SYMBOL_DEFINITION_REGULAR: 321 sym.def = LDPK_DEF; 322 break; 323 case LTO_SYMBOL_DEFINITION_UNDEFINED: 324 sym.def = LDPK_UNDEF; 325 break; 326 case LTO_SYMBOL_DEFINITION_TENTATIVE: 327 sym.def = LDPK_COMMON; 328 break; 329 case LTO_SYMBOL_DEFINITION_WEAK: 330 sym.comdat_key = sym.name; 331 sym.def = LDPK_WEAKDEF; 332 break; 333 case LTO_SYMBOL_DEFINITION_WEAKUNDEF: 334 sym.def = LDPK_WEAKUNDEF; 335 break; 336 default: 337 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition); 338 return LDPS_ERR; 339 } 340 341 sym.size = 0; 342 343 sym.resolution = LDPR_UNKNOWN; 344 } 345 346 cf.syms.reserve(cf.syms.size()); 347 348 if (!cf.syms.empty()) { 349 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) { 350 (*message)(LDPL_ERROR, "Unable to add symbols!"); 351 return LDPS_ERR; 352 } 353 } 354 355 if (code_gen) 356 lto_codegen_add_module(code_gen, M); 357 358 lto_module_dispose(M); 359 360 return LDPS_OK; 361 } 362 363 /// all_symbols_read_hook - gold informs us that all symbols have been read. 364 /// At this point, we use get_symbols to see if any of our definitions have 365 /// been overridden by a native object file. Then, perform optimization and 366 /// codegen. 367 static ld_plugin_status all_symbols_read_hook(void) { 368 std::ofstream api_file; 369 assert(code_gen); 370 371 if (options::generate_api_file) { 372 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc); 373 if (!api_file.is_open()) { 374 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing."); 375 abort(); 376 } 377 } 378 379 // If we don't preserve any symbols, libLTO will assume that all symbols are 380 // needed. Keep all symbols unless we're producing a final executable. 381 bool anySymbolsPreserved = false; 382 for (std::list<claimed_file>::iterator I = Modules.begin(), 383 E = Modules.end(); I != E; ++I) { 384 if (I->syms.empty()) 385 continue; 386 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]); 387 for (unsigned i = 0, e = I->syms.size(); i != e; i++) { 388 if (I->syms[i].resolution == LDPR_PREVAILING_DEF) { 389 lto_codegen_add_must_preserve_symbol(code_gen, I->syms[i].name); 390 anySymbolsPreserved = true; 391 392 if (options::generate_api_file) 393 api_file << I->syms[i].name << "\n"; 394 } 395 } 396 } 397 398 if (options::generate_api_file) 399 api_file.close(); 400 401 if (!anySymbolsPreserved) { 402 // All of the IL is unnecessary! 403 lto_codegen_dispose(code_gen); 404 return LDPS_OK; 405 } 406 407 lto_codegen_set_pic_model(code_gen, output_type); 408 lto_codegen_set_debug_model(code_gen, LTO_DEBUG_MODEL_DWARF); 409 if (!options::mcpu.empty()) 410 lto_codegen_set_cpu(code_gen, options::mcpu.c_str()); 411 412 // Pass through extra options to the code generator. 413 if (!options::extra.empty()) { 414 for (std::vector<std::string>::iterator it = options::extra.begin(); 415 it != options::extra.end(); ++it) { 416 lto_codegen_debug_options(code_gen, (*it).c_str()); 417 } 418 } 419 420 if (options::generate_bc_file != options::BC_NO) { 421 std::string path; 422 if (options::generate_bc_file == options::BC_ONLY) 423 path = output_name; 424 else if (!options::bc_path.empty()) 425 path = options::bc_path; 426 else 427 path = output_name + ".bc"; 428 bool err = lto_codegen_write_merged_modules(code_gen, path.c_str()); 429 if (err) 430 (*message)(LDPL_FATAL, "Failed to write the output file."); 431 if (options::generate_bc_file == options::BC_ONLY) 432 exit(0); 433 } 434 const char *objPath; 435 if (lto_codegen_compile_to_file(code_gen, &objPath)) { 436 (*message)(LDPL_ERROR, "Could not produce a combined object file\n"); 437 } 438 439 lto_codegen_dispose(code_gen); 440 for (std::list<claimed_file>::iterator I = Modules.begin(), 441 E = Modules.end(); I != E; ++I) { 442 for (unsigned i = 0; i != I->syms.size(); ++i) { 443 ld_plugin_symbol &sym = I->syms[i]; 444 free(sym.name); 445 } 446 } 447 448 if ((*add_input_file)(objPath) != LDPS_OK) { 449 (*message)(LDPL_ERROR, "Unable to add .o file to the link."); 450 (*message)(LDPL_ERROR, "File left behind in: %s", objPath); 451 return LDPS_ERR; 452 } 453 454 if (!options::extra_library_path.empty() && 455 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) { 456 (*message)(LDPL_ERROR, "Unable to set the extra library path."); 457 return LDPS_ERR; 458 } 459 460 if (options::obj_path.empty()) 461 Cleanup.push_back(sys::Path(objPath)); 462 463 return LDPS_OK; 464 } 465 466 static ld_plugin_status cleanup_hook(void) { 467 std::string ErrMsg; 468 469 for (int i = 0, e = Cleanup.size(); i != e; ++i) 470 if (Cleanup[i].eraseFromDisk(false, &ErrMsg)) 471 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(), 472 ErrMsg.c_str()); 473 474 return LDPS_OK; 475 } 476
