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" // plugin-api.h requires HAVE_STDINT_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 // FIXME: Replace 3 with LDPO_PIE once that is in a released binutils. 157 case 3: // position independent executable 158 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC; 159 break; 160 case LDPO_EXEC: // .exe 161 output_type = LTO_CODEGEN_PIC_MODEL_STATIC; 162 break; 163 default: 164 (*message)(LDPL_ERROR, "Unknown output file type %d", 165 tv->tv_u.tv_val); 166 return LDPS_ERR; 167 } 168 // TODO: add an option to disable PIC. 169 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC; 170 break; 171 case LDPT_OPTION: 172 options::process_plugin_option(tv->tv_u.tv_string); 173 break; 174 case LDPT_REGISTER_CLAIM_FILE_HOOK: { 175 ld_plugin_register_claim_file callback; 176 callback = tv->tv_u.tv_register_claim_file; 177 178 if ((*callback)(claim_file_hook) != LDPS_OK) 179 return LDPS_ERR; 180 181 registeredClaimFile = true; 182 } break; 183 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: { 184 ld_plugin_register_all_symbols_read callback; 185 callback = tv->tv_u.tv_register_all_symbols_read; 186 187 if ((*callback)(all_symbols_read_hook) != LDPS_OK) 188 return LDPS_ERR; 189 190 code_gen = lto_codegen_create(); 191 } break; 192 case LDPT_REGISTER_CLEANUP_HOOK: { 193 ld_plugin_register_cleanup callback; 194 callback = tv->tv_u.tv_register_cleanup; 195 196 if ((*callback)(cleanup_hook) != LDPS_OK) 197 return LDPS_ERR; 198 } break; 199 case LDPT_ADD_SYMBOLS: 200 add_symbols = tv->tv_u.tv_add_symbols; 201 break; 202 case LDPT_GET_SYMBOLS: 203 get_symbols = tv->tv_u.tv_get_symbols; 204 break; 205 case LDPT_ADD_INPUT_FILE: 206 add_input_file = tv->tv_u.tv_add_input_file; 207 break; 208 case LDPT_ADD_INPUT_LIBRARY: 209 add_input_library = tv->tv_u.tv_add_input_file; 210 break; 211 case LDPT_SET_EXTRA_LIBRARY_PATH: 212 set_extra_library_path = tv->tv_u.tv_set_extra_library_path; 213 break; 214 case LDPT_GET_VIEW: 215 get_view = tv->tv_u.tv_get_view; 216 break; 217 case LDPT_MESSAGE: 218 message = tv->tv_u.tv_message; 219 break; 220 default: 221 break; 222 } 223 } 224 225 if (!registeredClaimFile) { 226 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold."); 227 return LDPS_ERR; 228 } 229 if (!add_symbols) { 230 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold."); 231 return LDPS_ERR; 232 } 233 234 return LDPS_OK; 235 } 236 237 /// claim_file_hook - called by gold to see whether this file is one that 238 /// our plugin can handle. We'll try to open it and register all the symbols 239 /// with add_symbol if possible. 240 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file, 241 int *claimed) { 242 lto_module_t M; 243 const void *view; 244 OwningPtr<MemoryBuffer> buffer; 245 if (get_view) { 246 if (get_view(file->handle, &view) != LDPS_OK) { 247 (*message)(LDPL_ERROR, "Failed to get a view of %s", file->name); 248 return LDPS_ERR; 249 } 250 } else { 251 int64_t offset = 0; 252 // Gold has found what might be IR part-way inside of a file, such as 253 // an .a archive. 254 if (file->offset) { 255 offset = file->offset; 256 } 257 if (error_code ec = 258 MemoryBuffer::getOpenFile(file->fd, file->name, buffer, file->filesize, 259 -1, offset, false)) { 260 (*message)(LDPL_ERROR, ec.message().c_str()); 261 return LDPS_ERR; 262 } 263 view = buffer->getBufferStart(); 264 } 265 266 if (!lto_module_is_object_file_in_memory(view, file->filesize)) 267 return LDPS_OK; 268 269 M = lto_module_create_from_memory(view, file->filesize); 270 if (!M) { 271 if (const char* msg = lto_get_error_message()) { 272 (*message)(LDPL_ERROR, 273 "LLVM gold plugin has failed to create LTO module: %s", 274 msg); 275 return LDPS_ERR; 276 } 277 return LDPS_OK; 278 } 279 280 *claimed = 1; 281 Modules.resize(Modules.size() + 1); 282 claimed_file &cf = Modules.back(); 283 284 if (!options::triple.empty()) 285 lto_module_set_target_triple(M, options::triple.c_str()); 286 287 cf.handle = file->handle; 288 unsigned sym_count = lto_module_get_num_symbols(M); 289 cf.syms.reserve(sym_count); 290 291 for (unsigned i = 0; i != sym_count; ++i) { 292 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(M, i); 293 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL) 294 continue; 295 296 cf.syms.push_back(ld_plugin_symbol()); 297 ld_plugin_symbol &sym = cf.syms.back(); 298 sym.name = const_cast<char *>(lto_module_get_symbol_name(M, i)); 299 sym.name = strdup(sym.name); 300 sym.version = NULL; 301 302 int scope = attrs & LTO_SYMBOL_SCOPE_MASK; 303 switch (scope) { 304 case LTO_SYMBOL_SCOPE_HIDDEN: 305 sym.visibility = LDPV_HIDDEN; 306 break; 307 case LTO_SYMBOL_SCOPE_PROTECTED: 308 sym.visibility = LDPV_PROTECTED; 309 break; 310 case 0: // extern 311 case LTO_SYMBOL_SCOPE_DEFAULT: 312 sym.visibility = LDPV_DEFAULT; 313 break; 314 default: 315 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope); 316 return LDPS_ERR; 317 } 318 319 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK; 320 sym.comdat_key = NULL; 321 switch (definition) { 322 case LTO_SYMBOL_DEFINITION_REGULAR: 323 sym.def = LDPK_DEF; 324 break; 325 case LTO_SYMBOL_DEFINITION_UNDEFINED: 326 sym.def = LDPK_UNDEF; 327 break; 328 case LTO_SYMBOL_DEFINITION_TENTATIVE: 329 sym.def = LDPK_COMMON; 330 break; 331 case LTO_SYMBOL_DEFINITION_WEAK: 332 sym.comdat_key = sym.name; 333 sym.def = LDPK_WEAKDEF; 334 break; 335 case LTO_SYMBOL_DEFINITION_WEAKUNDEF: 336 sym.def = LDPK_WEAKUNDEF; 337 break; 338 default: 339 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition); 340 return LDPS_ERR; 341 } 342 343 sym.size = 0; 344 345 sym.resolution = LDPR_UNKNOWN; 346 } 347 348 cf.syms.reserve(cf.syms.size()); 349 350 if (!cf.syms.empty()) { 351 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) { 352 (*message)(LDPL_ERROR, "Unable to add symbols!"); 353 return LDPS_ERR; 354 } 355 } 356 357 if (code_gen) 358 lto_codegen_add_module(code_gen, M); 359 360 lto_module_dispose(M); 361 362 return LDPS_OK; 363 } 364 365 /// all_symbols_read_hook - gold informs us that all symbols have been read. 366 /// At this point, we use get_symbols to see if any of our definitions have 367 /// been overridden by a native object file. Then, perform optimization and 368 /// codegen. 369 static ld_plugin_status all_symbols_read_hook(void) { 370 std::ofstream api_file; 371 assert(code_gen); 372 373 if (options::generate_api_file) { 374 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc); 375 if (!api_file.is_open()) { 376 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing."); 377 abort(); 378 } 379 } 380 381 // If we don't preserve any symbols, libLTO will assume that all symbols are 382 // needed. Keep all symbols unless we're producing a final executable. 383 bool anySymbolsPreserved = false; 384 for (std::list<claimed_file>::iterator I = Modules.begin(), 385 E = Modules.end(); I != E; ++I) { 386 if (I->syms.empty()) 387 continue; 388 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]); 389 for (unsigned i = 0, e = I->syms.size(); i != e; i++) { 390 if (I->syms[i].resolution == LDPR_PREVAILING_DEF) { 391 lto_codegen_add_must_preserve_symbol(code_gen, I->syms[i].name); 392 anySymbolsPreserved = true; 393 394 if (options::generate_api_file) 395 api_file << I->syms[i].name << "\n"; 396 } 397 } 398 } 399 400 if (options::generate_api_file) 401 api_file.close(); 402 403 if (!anySymbolsPreserved) { 404 // All of the IL is unnecessary! 405 lto_codegen_dispose(code_gen); 406 return LDPS_OK; 407 } 408 409 lto_codegen_set_pic_model(code_gen, output_type); 410 lto_codegen_set_debug_model(code_gen, LTO_DEBUG_MODEL_DWARF); 411 if (!options::mcpu.empty()) 412 lto_codegen_set_cpu(code_gen, options::mcpu.c_str()); 413 414 // Pass through extra options to the code generator. 415 if (!options::extra.empty()) { 416 for (std::vector<std::string>::iterator it = options::extra.begin(); 417 it != options::extra.end(); ++it) { 418 lto_codegen_debug_options(code_gen, (*it).c_str()); 419 } 420 } 421 422 if (options::generate_bc_file != options::BC_NO) { 423 std::string path; 424 if (options::generate_bc_file == options::BC_ONLY) 425 path = output_name; 426 else if (!options::bc_path.empty()) 427 path = options::bc_path; 428 else 429 path = output_name + ".bc"; 430 bool err = lto_codegen_write_merged_modules(code_gen, path.c_str()); 431 if (err) 432 (*message)(LDPL_FATAL, "Failed to write the output file."); 433 if (options::generate_bc_file == options::BC_ONLY) 434 exit(0); 435 } 436 const char *objPath; 437 if (lto_codegen_compile_to_file(code_gen, &objPath)) { 438 (*message)(LDPL_ERROR, "Could not produce a combined object file\n"); 439 } 440 441 lto_codegen_dispose(code_gen); 442 for (std::list<claimed_file>::iterator I = Modules.begin(), 443 E = Modules.end(); I != E; ++I) { 444 for (unsigned i = 0; i != I->syms.size(); ++i) { 445 ld_plugin_symbol &sym = I->syms[i]; 446 free(sym.name); 447 } 448 } 449 450 if ((*add_input_file)(objPath) != LDPS_OK) { 451 (*message)(LDPL_ERROR, "Unable to add .o file to the link."); 452 (*message)(LDPL_ERROR, "File left behind in: %s", objPath); 453 return LDPS_ERR; 454 } 455 456 if (!options::extra_library_path.empty() && 457 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) { 458 (*message)(LDPL_ERROR, "Unable to set the extra library path."); 459 return LDPS_ERR; 460 } 461 462 if (options::obj_path.empty()) 463 Cleanup.push_back(sys::Path(objPath)); 464 465 return LDPS_OK; 466 } 467 468 static ld_plugin_status cleanup_hook(void) { 469 std::string ErrMsg; 470 471 for (int i = 0, e = Cleanup.size(); i != e; ++i) 472 if (Cleanup[i].eraseFromDisk(false, &ErrMsg)) 473 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(), 474 ErrMsg.c_str()); 475 476 return LDPS_OK; 477 } 478
