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::vector<std::string> pass_through;
77 static std::string extra_library_path;
78 static std::string triple;
79 static std::string mcpu;
80 // Additional options to pass into the code generator.
81 // Note: This array will contain all plugin options which are not claimed
82 // as plugin exclusive to pass to the code generator.
83 // For example, "generate-api-file" and "as"options are for the plugin
84 // use only and will not be passed.
85 static std::vector<std::string> extra;
87 static void process_plugin_option(const char* opt_)
91 llvm::StringRef opt = opt_;
93 if (opt == "generate-api-file") {
94 generate_api_file = true;
95 } else if (opt.startswith("mcpu=")) {
96 mcpu = opt.substr(strlen("mcpu="));
97 } else if (opt.startswith("extra-library-path=")) {
98 extra_library_path = opt.substr(strlen("extra_library_path="));
99 } else if (opt.startswith("pass-through=")) {
100 llvm::StringRef item = opt.substr(strlen("pass-through="));
101 pass_through.push_back(item.str());
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_);
120 // Save this option to pass to the code generator.
121 extra.push_back(opt);
126 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
128 static ld_plugin_status all_symbols_read_hook(void);
129 static ld_plugin_status cleanup_hook(void);
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
139 bool registeredClaimFile = false;
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;
146 case LDPT_GOLD_VERSION: // major * 100 + minor
147 gold_version = tv->tv_u.tv_val;
149 case LDPT_OUTPUT_NAME:
150 output_name = tv->tv_u.tv_string;
152 case LDPT_LINKER_OUTPUT:
153 switch (tv->tv_u.tv_val) {
155 case LDPO_DYN: // .so
156 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
158 case LDPO_EXEC: // .exe
159 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
162 (*message)(LDPL_ERROR, "Unknown output file type %d",
166 // TODO: add an option to disable PIC.
167 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
170 options::process_plugin_option(tv->tv_u.tv_string);
172 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
173 ld_plugin_register_claim_file callback;
174 callback = tv->tv_u.tv_register_claim_file;
176 if ((*callback)(claim_file_hook) != LDPS_OK)
179 registeredClaimFile = true;
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;
185 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
188 code_gen = lto_codegen_create();
190 case LDPT_REGISTER_CLEANUP_HOOK: {
191 ld_plugin_register_cleanup callback;
192 callback = tv->tv_u.tv_register_cleanup;
194 if ((*callback)(cleanup_hook) != LDPS_OK)
197 case LDPT_ADD_SYMBOLS:
198 add_symbols = tv->tv_u.tv_add_symbols;
200 case LDPT_GET_SYMBOLS:
201 get_symbols = tv->tv_u.tv_get_symbols;
203 case LDPT_ADD_INPUT_FILE:
204 add_input_file = tv->tv_u.tv_add_input_file;
206 case LDPT_ADD_INPUT_LIBRARY:
207 add_input_library = tv->tv_u.tv_add_input_file;
209 case LDPT_SET_EXTRA_LIBRARY_PATH:
210 set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
213 message = tv->tv_u.tv_message;
220 if (!registeredClaimFile) {
221 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
225 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
232 /// claim_file_hook - called by gold to see whether this file is one that
233 /// our plugin can handle. We'll try to open it and register all the symbols
234 /// with add_symbol if possible.
235 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
240 // Gold has found what might be IR part-way inside of a file, such as
242 if (lseek(file->fd, file->offset, SEEK_SET) == -1) {
243 (*message)(LDPL_ERROR,
244 "Failed to seek to archive member of %s at offset %d: %s\n",
246 file->offset, sys::StrError(errno).c_str());
249 void *buf = malloc(file->filesize);
251 (*message)(LDPL_ERROR,
252 "Failed to allocate buffer for archive member of size: %d\n",
256 if (read(file->fd, buf, file->filesize) != file->filesize) {
257 (*message)(LDPL_ERROR,
258 "Failed to read archive member of %s at offset %d: %s\n",
261 sys::StrError(errno).c_str());
265 if (!lto_module_is_object_file_in_memory(buf, file->filesize)) {
269 M = lto_module_create_from_memory(buf, file->filesize);
271 (*message)(LDPL_ERROR, "Failed to create LLVM module: %s",
272 lto_get_error_message());
277 // FIXME: We should not need to pass -1 as the file size, but there
278 // is a bug in BFD that causes it to pass 0 to us. Remove this once
280 off_t size = file->filesize ? file->filesize : -1;
282 // FIXME: We should not need to reset the position in the file, but there
283 // is a bug in BFD. Remove this once that is fixed.
284 off_t old_pos = lseek(file->fd, 0, SEEK_CUR);
286 lseek(file->fd, 0, SEEK_SET);
287 M = lto_module_create_from_fd(file->fd, file->name, size);
289 lseek(file->fd, old_pos, SEEK_SET);
295 Modules.resize(Modules.size() + 1);
296 claimed_file &cf = Modules.back();
298 if (!options::triple.empty())
299 lto_module_set_target_triple(M, options::triple.c_str());
301 cf.handle = file->handle;
302 unsigned sym_count = lto_module_get_num_symbols(M);
303 cf.syms.reserve(sym_count);
305 for (unsigned i = 0; i != sym_count; ++i) {
306 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(M, i);
307 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
310 cf.syms.push_back(ld_plugin_symbol());
311 ld_plugin_symbol &sym = cf.syms.back();
312 sym.name = const_cast<char *>(lto_module_get_symbol_name(M, i));
313 sym.name = strdup(sym.name);
316 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
318 case LTO_SYMBOL_SCOPE_HIDDEN:
319 sym.visibility = LDPV_HIDDEN;
321 case LTO_SYMBOL_SCOPE_PROTECTED:
322 sym.visibility = LDPV_PROTECTED;
325 case LTO_SYMBOL_SCOPE_DEFAULT:
326 sym.visibility = LDPV_DEFAULT;
329 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
333 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
334 sym.comdat_key = NULL;
335 switch (definition) {
336 case LTO_SYMBOL_DEFINITION_REGULAR:
339 case LTO_SYMBOL_DEFINITION_UNDEFINED:
340 sym.def = LDPK_UNDEF;
342 case LTO_SYMBOL_DEFINITION_TENTATIVE:
343 sym.def = LDPK_COMMON;
345 case LTO_SYMBOL_DEFINITION_WEAK:
346 sym.comdat_key = sym.name;
347 sym.def = LDPK_WEAKDEF;
349 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
350 sym.def = LDPK_WEAKUNDEF;
353 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
359 sym.resolution = LDPR_UNKNOWN;
362 cf.syms.reserve(cf.syms.size());
364 if (!cf.syms.empty()) {
365 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
366 (*message)(LDPL_ERROR, "Unable to add symbols!");
372 lto_codegen_add_module(code_gen, M);
374 lto_module_dispose(M);
379 /// all_symbols_read_hook - gold informs us that all symbols have been read.
380 /// At this point, we use get_symbols to see if any of our definitions have
381 /// been overridden by a native object file. Then, perform optimization and
383 static ld_plugin_status all_symbols_read_hook(void) {
384 std::ofstream api_file;
387 if (options::generate_api_file) {
388 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
389 if (!api_file.is_open()) {
390 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
395 // If we don't preserve any symbols, libLTO will assume that all symbols are
396 // needed. Keep all symbols unless we're producing a final executable.
397 bool anySymbolsPreserved = false;
398 for (std::list<claimed_file>::iterator I = Modules.begin(),
399 E = Modules.end(); I != E; ++I) {
400 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
401 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
402 if (I->syms[i].resolution == LDPR_PREVAILING_DEF) {
403 lto_codegen_add_must_preserve_symbol(code_gen, I->syms[i].name);
404 anySymbolsPreserved = true;
406 if (options::generate_api_file)
407 api_file << I->syms[i].name << "\n";
412 if (options::generate_api_file)
415 if (!anySymbolsPreserved) {
416 // All of the IL is unnecessary!
417 lto_codegen_dispose(code_gen);
421 lto_codegen_set_pic_model(code_gen, output_type);
422 lto_codegen_set_debug_model(code_gen, LTO_DEBUG_MODEL_DWARF);
423 if (!options::mcpu.empty())
424 lto_codegen_set_cpu(code_gen, options::mcpu.c_str());
426 // Pass through extra options to the code generator.
427 if (!options::extra.empty()) {
428 for (std::vector<std::string>::iterator it = options::extra.begin();
429 it != options::extra.end(); ++it) {
430 lto_codegen_debug_options(code_gen, (*it).c_str());
434 if (options::generate_bc_file != options::BC_NO) {
436 if (options::generate_bc_file == options::BC_ONLY)
438 else if (!options::bc_path.empty())
439 path = options::bc_path;
441 path = output_name + ".bc";
442 bool err = lto_codegen_write_merged_modules(code_gen, path.c_str());
444 (*message)(LDPL_FATAL, "Failed to write the output file.");
445 if (options::generate_bc_file == options::BC_ONLY)
449 const char *buffer = static_cast<const char *>(lto_codegen_compile(code_gen,
455 sys::Path uniqueObjPath("/tmp/llvmgold.o");
456 if (!options::obj_path.empty()) {
457 objPath = options::obj_path.c_str();
459 if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) {
460 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
463 objPath = uniqueObjPath.c_str();
465 tool_output_file objFile(objPath, ErrMsg,
466 raw_fd_ostream::F_Binary);
467 if (!ErrMsg.empty()) {
468 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
472 objFile.os().write(buffer, bufsize);
473 objFile.os().close();
474 if (objFile.os().has_error()) {
475 (*message)(LDPL_ERROR, "Error writing output file '%s'",
477 objFile.os().clear_error();
482 lto_codegen_dispose(code_gen);
483 for (std::list<claimed_file>::iterator I = Modules.begin(),
484 E = Modules.end(); I != E; ++I) {
485 for (unsigned i = 0; i != I->syms.size(); ++i) {
486 ld_plugin_symbol &sym = I->syms[i];
491 if ((*add_input_file)(objPath) != LDPS_OK) {
492 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
493 (*message)(LDPL_ERROR, "File left behind in: %s", objPath);
497 if (!options::extra_library_path.empty() &&
498 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) {
499 (*message)(LDPL_ERROR, "Unable to set the extra library path.");
503 for (std::vector<std::string>::iterator i = options::pass_through.begin(),
504 e = options::pass_through.end();
506 std::string &item = *i;
507 const char *item_p = item.c_str();
508 if (llvm::StringRef(item).startswith("-l")) {
509 if (add_input_library(item_p + 2) != LDPS_OK) {
510 (*message)(LDPL_ERROR, "Unable to add library to the link.");
514 if (add_input_file(item_p) != LDPS_OK) {
515 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
521 if (options::obj_path.empty())
522 Cleanup.push_back(sys::Path(objPath));
527 static ld_plugin_status cleanup_hook(void) {
530 for (int i = 0, e = Cleanup.size(); i != e; ++i)
531 if (Cleanup[i].eraseFromDisk(false, &ErrMsg))
532 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),