1 //===-- gold-plugin.cpp - Plugin to gold for Link Time Optimization ------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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 .
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Config/config.h"
16 #include "plugin-api.h"
18 #include "llvm-c/lto.h"
20 #include "llvm/Support/ToolOutputFile.h"
21 #include "llvm/Support/Errno.h"
22 #include "llvm/Support/Path.h"
23 #include "llvm/Support/Program.h"
32 // Support Windows/MinGW crazyness.
42 ld_plugin_status discard_message(int level, const char *format, ...) {
43 // Die loudly. Recent versions of Gold pass ld_plugin_message as the first
44 // callback in the transfer vector. This should never be called.
48 ld_plugin_add_symbols add_symbols = NULL;
49 ld_plugin_get_symbols get_symbols = NULL;
50 ld_plugin_add_input_file add_input_file = NULL;
51 ld_plugin_add_input_library add_input_library = NULL;
52 ld_plugin_set_extra_library_path set_extra_library_path = NULL;
53 ld_plugin_message message = discard_message;
60 std::vector<ld_plugin_symbol> syms;
63 lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
64 std::string output_name = "";
65 std::list<claimed_file> Modules;
66 std::vector<sys::Path> Cleanup;
67 lto_code_gen_t code_gen = NULL;
71 enum generate_bc { BC_NO, BC_ALSO, BC_ONLY };
72 static bool generate_api_file = false;
73 static generate_bc generate_bc_file = BC_NO;
74 static std::string bc_path;
75 static std::string obj_path;
76 static std::string as_path;
77 static std::vector<std::string> as_args;
78 static std::vector<std::string> pass_through;
79 static std::string extra_library_path;
80 static std::string triple;
81 static std::string mcpu;
82 // Additional options to pass into the code generator.
83 // Note: This array will contain all plugin options which are not claimed
84 // as plugin exclusive to pass to the code generator.
85 // For example, "generate-api-file" and "as"options are for the plugin
86 // use only and will not be passed.
87 static std::vector<std::string> extra;
89 static void process_plugin_option(const char* opt_)
93 llvm::StringRef opt = opt_;
95 if (opt == "generate-api-file") {
96 generate_api_file = true;
97 } else if (opt.startswith("mcpu=")) {
98 mcpu = opt.substr(strlen("mcpu="));
99 } else if (opt.startswith("as=")) {
100 if (!as_path.empty()) {
101 (*message)(LDPL_WARNING, "Path to as specified twice. "
102 "Discarding %s", opt_);
104 as_path = opt.substr(strlen("as="));
106 } else if (opt.startswith("as-arg=")) {
107 llvm::StringRef item = opt.substr(strlen("as-arg="));
108 as_args.push_back(item.str());
109 } else if (opt.startswith("extra-library-path=")) {
110 extra_library_path = opt.substr(strlen("extra_library_path="));
111 } else if (opt.startswith("pass-through=")) {
112 llvm::StringRef item = opt.substr(strlen("pass-through="));
113 pass_through.push_back(item.str());
114 } else if (opt.startswith("mtriple=")) {
115 triple = opt.substr(strlen("mtriple="));
116 } else if (opt.startswith("obj-path=")) {
117 obj_path = opt.substr(strlen("obj-path="));
118 } else if (opt == "emit-llvm") {
119 generate_bc_file = BC_ONLY;
120 } else if (opt == "also-emit-llvm") {
121 generate_bc_file = BC_ALSO;
122 } else if (opt.startswith("also-emit-llvm=")) {
123 llvm::StringRef path = opt.substr(strlen("also-emit-llvm="));
124 generate_bc_file = BC_ALSO;
125 if (!bc_path.empty()) {
126 (*message)(LDPL_WARNING, "Path to the output IL file specified twice. "
127 "Discarding %s", opt_);
132 // Save this option to pass to the code generator.
133 extra.push_back(opt);
138 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
140 static ld_plugin_status all_symbols_read_hook(void);
141 static ld_plugin_status cleanup_hook(void);
143 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
144 ld_plugin_status onload(ld_plugin_tv *tv) {
145 // We're given a pointer to the first transfer vector. We read through them
146 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
147 // contain pointers to functions that we need to call to register our own
148 // hooks. The others are addresses of functions we can use to call into gold
151 bool registeredClaimFile = false;
153 for (; tv->tv_tag != LDPT_NULL; ++tv) {
154 switch (tv->tv_tag) {
155 case LDPT_API_VERSION:
156 api_version = tv->tv_u.tv_val;
158 case LDPT_GOLD_VERSION: // major * 100 + minor
159 gold_version = tv->tv_u.tv_val;
161 case LDPT_OUTPUT_NAME:
162 output_name = tv->tv_u.tv_string;
164 case LDPT_LINKER_OUTPUT:
165 switch (tv->tv_u.tv_val) {
167 case LDPO_DYN: // .so
168 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
170 case LDPO_EXEC: // .exe
171 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
174 (*message)(LDPL_ERROR, "Unknown output file type %d",
178 // TODO: add an option to disable PIC.
179 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
182 options::process_plugin_option(tv->tv_u.tv_string);
184 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
185 ld_plugin_register_claim_file callback;
186 callback = tv->tv_u.tv_register_claim_file;
188 if ((*callback)(claim_file_hook) != LDPS_OK)
191 registeredClaimFile = true;
193 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
194 ld_plugin_register_all_symbols_read callback;
195 callback = tv->tv_u.tv_register_all_symbols_read;
197 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
200 code_gen = lto_codegen_create();
202 case LDPT_REGISTER_CLEANUP_HOOK: {
203 ld_plugin_register_cleanup callback;
204 callback = tv->tv_u.tv_register_cleanup;
206 if ((*callback)(cleanup_hook) != LDPS_OK)
209 case LDPT_ADD_SYMBOLS:
210 add_symbols = tv->tv_u.tv_add_symbols;
212 case LDPT_GET_SYMBOLS:
213 get_symbols = tv->tv_u.tv_get_symbols;
215 case LDPT_ADD_INPUT_FILE:
216 add_input_file = tv->tv_u.tv_add_input_file;
218 case LDPT_ADD_INPUT_LIBRARY:
219 add_input_library = tv->tv_u.tv_add_input_file;
221 case LDPT_SET_EXTRA_LIBRARY_PATH:
222 set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
225 message = tv->tv_u.tv_message;
232 if (!registeredClaimFile) {
233 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
237 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
244 /// claim_file_hook - called by gold to see whether this file is one that
245 /// our plugin can handle. We'll try to open it and register all the symbols
246 /// with add_symbol if possible.
247 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
252 // Gold has found what might be IR part-way inside of a file, such as
254 if (lseek(file->fd, file->offset, SEEK_SET) == -1) {
255 (*message)(LDPL_ERROR,
256 "Failed to seek to archive member of %s at offset %d: %s\n",
258 file->offset, sys::StrError(errno).c_str());
261 void *buf = malloc(file->filesize);
263 (*message)(LDPL_ERROR,
264 "Failed to allocate buffer for archive member of size: %d\n",
268 if (read(file->fd, buf, file->filesize) != file->filesize) {
269 (*message)(LDPL_ERROR,
270 "Failed to read archive member of %s at offset %d: %s\n",
273 sys::StrError(errno).c_str());
277 if (!lto_module_is_object_file_in_memory(buf, file->filesize)) {
281 M = lto_module_create_from_memory(buf, file->filesize);
283 (*message)(LDPL_ERROR, "Failed to create LLVM module: %s",
284 lto_get_error_message());
289 // FIXME: We should not need to pass -1 as the file size, but there
290 // is a bug in BFD that causes it to pass 0 to us. Remove this once
292 off_t size = file->filesize ? file->filesize : -1;
294 // FIXME: We should not need to reset the position in the file, but there
295 // is a bug in BFD. Remove this once that is fixed.
296 off_t old_pos = lseek(file->fd, 0, SEEK_CUR);
298 lseek(file->fd, 0, SEEK_SET);
299 M = lto_module_create_from_fd(file->fd, file->name, size);
301 lseek(file->fd, old_pos, SEEK_SET);
307 Modules.resize(Modules.size() + 1);
308 claimed_file &cf = Modules.back();
310 if (!options::triple.empty())
311 lto_module_set_target_triple(M, options::triple.c_str());
313 cf.handle = file->handle;
314 unsigned sym_count = lto_module_get_num_symbols(M);
315 cf.syms.reserve(sym_count);
317 for (unsigned i = 0; i != sym_count; ++i) {
318 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(M, i);
319 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
322 cf.syms.push_back(ld_plugin_symbol());
323 ld_plugin_symbol &sym = cf.syms.back();
324 sym.name = const_cast<char *>(lto_module_get_symbol_name(M, i));
325 sym.name = strdup(sym.name);
328 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
330 case LTO_SYMBOL_SCOPE_HIDDEN:
331 sym.visibility = LDPV_HIDDEN;
333 case LTO_SYMBOL_SCOPE_PROTECTED:
334 sym.visibility = LDPV_PROTECTED;
337 case LTO_SYMBOL_SCOPE_DEFAULT:
338 sym.visibility = LDPV_DEFAULT;
341 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
345 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
346 sym.comdat_key = NULL;
347 switch (definition) {
348 case LTO_SYMBOL_DEFINITION_REGULAR:
351 case LTO_SYMBOL_DEFINITION_UNDEFINED:
352 sym.def = LDPK_UNDEF;
354 case LTO_SYMBOL_DEFINITION_TENTATIVE:
355 sym.def = LDPK_COMMON;
357 case LTO_SYMBOL_DEFINITION_WEAK:
358 sym.comdat_key = sym.name;
359 sym.def = LDPK_WEAKDEF;
361 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
362 sym.def = LDPK_WEAKUNDEF;
365 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
371 sym.resolution = LDPR_UNKNOWN;
374 cf.syms.reserve(cf.syms.size());
376 if (!cf.syms.empty()) {
377 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
378 (*message)(LDPL_ERROR, "Unable to add symbols!");
384 lto_codegen_add_module(code_gen, M);
386 lto_module_dispose(M);
391 /// all_symbols_read_hook - gold informs us that all symbols have been read.
392 /// At this point, we use get_symbols to see if any of our definitions have
393 /// been overridden by a native object file. Then, perform optimization and
395 static ld_plugin_status all_symbols_read_hook(void) {
396 std::ofstream api_file;
399 if (options::generate_api_file) {
400 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
401 if (!api_file.is_open()) {
402 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
407 // If we don't preserve any symbols, libLTO will assume that all symbols are
408 // needed. Keep all symbols unless we're producing a final executable.
409 bool anySymbolsPreserved = false;
410 for (std::list<claimed_file>::iterator I = Modules.begin(),
411 E = Modules.end(); I != E; ++I) {
412 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
413 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
414 if (I->syms[i].resolution == LDPR_PREVAILING_DEF) {
415 lto_codegen_add_must_preserve_symbol(code_gen, I->syms[i].name);
416 anySymbolsPreserved = true;
418 if (options::generate_api_file)
419 api_file << I->syms[i].name << "\n";
424 if (options::generate_api_file)
427 if (!anySymbolsPreserved) {
428 // All of the IL is unnecessary!
429 lto_codegen_dispose(code_gen);
433 lto_codegen_set_pic_model(code_gen, output_type);
434 lto_codegen_set_debug_model(code_gen, LTO_DEBUG_MODEL_DWARF);
435 if (!options::as_path.empty()) {
436 sys::Path p = sys::Program::FindProgramByName(options::as_path);
437 lto_codegen_set_assembler_path(code_gen, p.c_str());
439 if (!options::as_args.empty()) {
440 std::vector<const char *> as_args_p;
441 for (std::vector<std::string>::iterator I = options::as_args.begin(),
442 E = options::as_args.end(); I != E; ++I) {
443 as_args_p.push_back(I->c_str());
445 lto_codegen_set_assembler_args(code_gen, &as_args_p[0], as_args_p.size());
447 if (!options::mcpu.empty())
448 lto_codegen_set_cpu(code_gen, options::mcpu.c_str());
450 // Pass through extra options to the code generator.
451 if (!options::extra.empty()) {
452 for (std::vector<std::string>::iterator it = options::extra.begin();
453 it != options::extra.end(); ++it) {
454 lto_codegen_debug_options(code_gen, (*it).c_str());
458 if (options::generate_bc_file != options::BC_NO) {
460 if (options::generate_bc_file == options::BC_ONLY)
462 else if (!options::bc_path.empty())
463 path = options::bc_path;
465 path = output_name + ".bc";
466 bool err = lto_codegen_write_merged_modules(code_gen, path.c_str());
468 (*message)(LDPL_FATAL, "Failed to write the output file.");
469 if (options::generate_bc_file == options::BC_ONLY)
473 const char *buffer = static_cast<const char *>(lto_codegen_compile(code_gen,
479 sys::Path uniqueObjPath("/tmp/llvmgold.o");
480 if (!options::obj_path.empty()) {
481 objPath = options::obj_path.c_str();
483 if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) {
484 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
487 objPath = uniqueObjPath.c_str();
489 tool_output_file objFile(objPath, ErrMsg,
490 raw_fd_ostream::F_Binary);
491 if (!ErrMsg.empty()) {
492 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
496 objFile.os().write(buffer, bufsize);
497 objFile.os().close();
498 if (objFile.os().has_error()) {
499 (*message)(LDPL_ERROR, "Error writing output file '%s'",
501 objFile.os().clear_error();
506 lto_codegen_dispose(code_gen);
507 for (std::list<claimed_file>::iterator I = Modules.begin(),
508 E = Modules.end(); I != E; ++I) {
509 for (unsigned i = 0; i != I->syms.size(); ++i) {
510 ld_plugin_symbol &sym = I->syms[i];
515 if ((*add_input_file)(objPath) != LDPS_OK) {
516 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
517 (*message)(LDPL_ERROR, "File left behind in: %s", objPath);
521 if (!options::extra_library_path.empty() &&
522 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) {
523 (*message)(LDPL_ERROR, "Unable to set the extra library path.");
527 for (std::vector<std::string>::iterator i = options::pass_through.begin(),
528 e = options::pass_through.end();
530 std::string &item = *i;
531 const char *item_p = item.c_str();
532 if (llvm::StringRef(item).startswith("-l")) {
533 if (add_input_library(item_p + 2) != LDPS_OK) {
534 (*message)(LDPL_ERROR, "Unable to add library to the link.");
538 if (add_input_file(item_p) != LDPS_OK) {
539 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
545 if (options::obj_path.empty())
546 Cleanup.push_back(sys::Path(objPath));
551 static ld_plugin_status cleanup_hook(void) {
554 for (int i = 0, e = Cleanup.size(); i != e; ++i)
555 if (Cleanup[i].eraseFromDisk(false, &ErrMsg))
556 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),