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 #include "llvm-c/lto.h" 18 #include "llvm/ADT/OwningPtr.h" 19 #include "llvm/Support/Errno.h" 20 #include "llvm/Support/FileSystem.h" 21 #include "llvm/Support/MemoryBuffer.h" 22 #include "llvm/Support/Path.h" 23 #include "llvm/Support/Program.h" 24 #include "llvm/Support/ToolOutputFile.h" 25 #include "llvm/Support/system_error.h" 26 #include <cerrno> 27 #include <cstdlib> 28 #include <cstring> 29 #include <fstream> 30 #include <list> 31 #include <vector> 32 33 // Support Windows/MinGW crazyness. 34 #ifdef _WIN32 35 # include <io.h> 36 # define lseek _lseek 37 # define read _read 38 #endif 39 40 using namespace llvm; 41 42 namespace { 43 ld_plugin_status discard_message(int level, const char *format, ...) { 44 // Die loudly. Recent versions of Gold pass ld_plugin_message as the first 45 // callback in the transfer vector. This should never be called. 46 abort(); 47 } 48 49 ld_plugin_add_symbols add_symbols = NULL; 50 ld_plugin_get_symbols get_symbols = NULL; 51 ld_plugin_add_input_file add_input_file = NULL; 52 ld_plugin_add_input_library add_input_library = NULL; 53 ld_plugin_set_extra_library_path set_extra_library_path = NULL; 54 ld_plugin_get_view get_view = NULL; 55 ld_plugin_message message = discard_message; 56 57 int api_version = 0; 58 int gold_version = 0; 59 60 struct claimed_file { 61 void *handle; 62 std::vector<ld_plugin_symbol> syms; 63 }; 64 65 lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC; 66 std::string output_name = ""; 67 std::list<claimed_file> Modules; 68 std::vector<std::string> Cleanup; 69 lto_code_gen_t code_gen = NULL; 70 } 71 72 namespace options { 73 enum generate_bc { BC_NO, BC_ALSO, BC_ONLY }; 74 static bool generate_api_file = false; 75 static generate_bc generate_bc_file = BC_NO; 76 static std::string bc_path; 77 static std::string obj_path; 78 static std::string extra_library_path; 79 static std::string triple; 80 static std::string mcpu; 81 // Additional options to pass into the code generator. 82 // Note: This array will contain all plugin options which are not claimed 83 // as plugin exclusive to pass to the code generator. 84 // For example, "generate-api-file" and "as"options are for the plugin 85 // use only and will not be passed. 86 static std::vector<std::string> extra; 87 88 static void process_plugin_option(const char* opt_) 89 { 90 if (opt_ == NULL) 91 return; 92 llvm::StringRef opt = opt_; 93 94 if (opt == "generate-api-file") { 95 generate_api_file = true; 96 } else if (opt.startswith("mcpu=")) { 97 mcpu = opt.substr(strlen("mcpu=")); 98 } else if (opt.startswith("extra-library-path=")) { 99 extra_library_path = opt.substr(strlen("extra_library_path=")); 100 } else if (opt.startswith("mtriple=")) { 101 triple = opt.substr(strlen("mtriple=")); 102 } else if (opt.startswith("obj-path=")) { 103 obj_path = opt.substr(strlen("obj-path=")); 104 } else if (opt == "emit-llvm") { 105 generate_bc_file = BC_ONLY; 106 } else if (opt == "also-emit-llvm") { 107 generate_bc_file = BC_ALSO; 108 } else if (opt.startswith("also-emit-llvm=")) { 109 llvm::StringRef path = opt.substr(strlen("also-emit-llvm=")); 110 generate_bc_file = BC_ALSO; 111 if (!bc_path.empty()) { 112 (*message)(LDPL_WARNING, "Path to the output IL file specified twice. " 113 "Discarding %s", opt_); 114 } else { 115 bc_path = path; 116 } 117 } else { 118 // Save this option to pass to the code generator. 119 extra.push_back(opt); 120 } 121 } 122 } 123 124 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file, 125 int *claimed); 126 static ld_plugin_status all_symbols_read_hook(void); 127 static ld_plugin_status cleanup_hook(void); 128 129 extern "C" ld_plugin_status onload(ld_plugin_tv *tv); 130 ld_plugin_status onload(ld_plugin_tv *tv) { 131 // We're given a pointer to the first transfer vector. We read through them 132 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values 133 // contain pointers to functions that we need to call to register our own 134 // hooks. The others are addresses of functions we can use to call into gold 135 // for services. 136 137 bool registeredClaimFile = false; 138 139 for (; tv->tv_tag != LDPT_NULL; ++tv) { 140 switch (tv->tv_tag) { 141 case LDPT_API_VERSION: 142 api_version = tv->tv_u.tv_val; 143 break; 144 case LDPT_GOLD_VERSION: // major * 100 + minor 145 gold_version = tv->tv_u.tv_val; 146 break; 147 case LDPT_OUTPUT_NAME: 148 output_name = tv->tv_u.tv_string; 149 break; 150 case LDPT_LINKER_OUTPUT: 151 switch (tv->tv_u.tv_val) { 152 case LDPO_REL: // .o 153 case LDPO_DYN: // .so 154 // FIXME: Replace 3 with LDPO_PIE once that is in a released binutils. 155 case 3: // position independent executable 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 = MemoryBuffer::getOpenFileSlice( 256 file->fd, file->name, buffer, file->filesize, offset)) { 257 (*message)(LDPL_ERROR, ec.message().c_str()); 258 return LDPS_ERR; 259 } 260 view = buffer->getBufferStart(); 261 } 262 263 if (!lto_module_is_object_file_in_memory(view, file->filesize)) 264 return LDPS_OK; 265 266 M = lto_module_create_from_memory(view, file->filesize); 267 if (!M) { 268 if (const char* msg = lto_get_error_message()) { 269 (*message)(LDPL_ERROR, 270 "LLVM gold plugin has failed to create LTO module: %s", 271 msg); 272 return LDPS_ERR; 273 } 274 return LDPS_OK; 275 } 276 277 *claimed = 1; 278 Modules.resize(Modules.size() + 1); 279 claimed_file &cf = Modules.back(); 280 281 if (!options::triple.empty()) 282 lto_module_set_target_triple(M, options::triple.c_str()); 283 284 cf.handle = file->handle; 285 unsigned sym_count = lto_module_get_num_symbols(M); 286 cf.syms.reserve(sym_count); 287 288 for (unsigned i = 0; i != sym_count; ++i) { 289 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(M, i); 290 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL) 291 continue; 292 293 cf.syms.push_back(ld_plugin_symbol()); 294 ld_plugin_symbol &sym = cf.syms.back(); 295 sym.name = const_cast<char *>(lto_module_get_symbol_name(M, i)); 296 sym.name = strdup(sym.name); 297 sym.version = NULL; 298 299 int scope = attrs & LTO_SYMBOL_SCOPE_MASK; 300 switch (scope) { 301 case LTO_SYMBOL_SCOPE_HIDDEN: 302 sym.visibility = LDPV_HIDDEN; 303 break; 304 case LTO_SYMBOL_SCOPE_PROTECTED: 305 sym.visibility = LDPV_PROTECTED; 306 break; 307 case 0: // extern 308 case LTO_SYMBOL_SCOPE_DEFAULT: 309 sym.visibility = LDPV_DEFAULT; 310 break; 311 default: 312 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope); 313 return LDPS_ERR; 314 } 315 316 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK; 317 sym.comdat_key = NULL; 318 switch (definition) { 319 case LTO_SYMBOL_DEFINITION_REGULAR: 320 sym.def = LDPK_DEF; 321 break; 322 case LTO_SYMBOL_DEFINITION_UNDEFINED: 323 sym.def = LDPK_UNDEF; 324 break; 325 case LTO_SYMBOL_DEFINITION_TENTATIVE: 326 sym.def = LDPK_COMMON; 327 break; 328 case LTO_SYMBOL_DEFINITION_WEAK: 329 sym.comdat_key = sym.name; 330 sym.def = LDPK_WEAKDEF; 331 break; 332 case LTO_SYMBOL_DEFINITION_WEAKUNDEF: 333 sym.def = LDPK_WEAKUNDEF; 334 break; 335 default: 336 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition); 337 return LDPS_ERR; 338 } 339 340 sym.size = 0; 341 342 sym.resolution = LDPR_UNKNOWN; 343 } 344 345 cf.syms.reserve(cf.syms.size()); 346 347 if (!cf.syms.empty()) { 348 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) { 349 (*message)(LDPL_ERROR, "Unable to add symbols!"); 350 return LDPS_ERR; 351 } 352 } 353 354 if (code_gen) 355 lto_codegen_add_module(code_gen, M); 356 357 lto_module_dispose(M); 358 359 return LDPS_OK; 360 } 361 362 /// all_symbols_read_hook - gold informs us that all symbols have been read. 363 /// At this point, we use get_symbols to see if any of our definitions have 364 /// been overridden by a native object file. Then, perform optimization and 365 /// codegen. 366 static ld_plugin_status all_symbols_read_hook(void) { 367 std::ofstream api_file; 368 assert(code_gen); 369 370 if (options::generate_api_file) { 371 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc); 372 if (!api_file.is_open()) { 373 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing."); 374 abort(); 375 } 376 } 377 378 for (std::list<claimed_file>::iterator I = Modules.begin(), 379 E = Modules.end(); I != E; ++I) { 380 if (I->syms.empty()) 381 continue; 382 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]); 383 for (unsigned i = 0, e = I->syms.size(); i != e; i++) { 384 if (I->syms[i].resolution == LDPR_PREVAILING_DEF) { 385 lto_codegen_add_must_preserve_symbol(code_gen, I->syms[i].name); 386 387 if (options::generate_api_file) 388 api_file << I->syms[i].name << "\n"; 389 } 390 } 391 } 392 393 if (options::generate_api_file) 394 api_file.close(); 395 396 lto_codegen_set_pic_model(code_gen, output_type); 397 lto_codegen_set_debug_model(code_gen, LTO_DEBUG_MODEL_DWARF); 398 if (!options::mcpu.empty()) 399 lto_codegen_set_cpu(code_gen, options::mcpu.c_str()); 400 401 // Pass through extra options to the code generator. 402 if (!options::extra.empty()) { 403 for (std::vector<std::string>::iterator it = options::extra.begin(); 404 it != options::extra.end(); ++it) { 405 lto_codegen_debug_options(code_gen, (*it).c_str()); 406 } 407 } 408 409 if (options::generate_bc_file != options::BC_NO) { 410 std::string path; 411 if (options::generate_bc_file == options::BC_ONLY) 412 path = output_name; 413 else if (!options::bc_path.empty()) 414 path = options::bc_path; 415 else 416 path = output_name + ".bc"; 417 bool err = lto_codegen_write_merged_modules(code_gen, path.c_str()); 418 if (err) 419 (*message)(LDPL_FATAL, "Failed to write the output file."); 420 if (options::generate_bc_file == options::BC_ONLY) 421 exit(0); 422 } 423 const char *objPath; 424 if (lto_codegen_compile_to_file(code_gen, &objPath)) { 425 (*message)(LDPL_ERROR, "Could not produce a combined object file\n"); 426 } 427 428 lto_codegen_dispose(code_gen); 429 for (std::list<claimed_file>::iterator I = Modules.begin(), 430 E = Modules.end(); I != E; ++I) { 431 for (unsigned i = 0; i != I->syms.size(); ++i) { 432 ld_plugin_symbol &sym = I->syms[i]; 433 free(sym.name); 434 } 435 } 436 437 if ((*add_input_file)(objPath) != LDPS_OK) { 438 (*message)(LDPL_ERROR, "Unable to add .o file to the link."); 439 (*message)(LDPL_ERROR, "File left behind in: %s", objPath); 440 return LDPS_ERR; 441 } 442 443 if (!options::extra_library_path.empty() && 444 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) { 445 (*message)(LDPL_ERROR, "Unable to set the extra library path."); 446 return LDPS_ERR; 447 } 448 449 if (options::obj_path.empty()) 450 Cleanup.push_back(objPath); 451 452 return LDPS_OK; 453 } 454 455 static ld_plugin_status cleanup_hook(void) { 456 for (int i = 0, e = Cleanup.size(); i != e; ++i) { 457 error_code EC = sys::fs::remove(Cleanup[i]); 458 if (EC) 459 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(), 460 EC.message().c_str()); 461 } 462 463 return LDPS_OK; 464 } 465
