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/raw_ostream.h"
21 #include "llvm/System/Errno.h"
22 #include "llvm/System/Path.h"
23 #include "llvm/System/Program.h"
35 ld_plugin_status discard_message(int level, const char *format, ...) {
36 // Die loudly. Recent versions of Gold pass ld_plugin_message as the first
37 // callback in the transfer vector. This should never be called.
41 ld_plugin_add_symbols add_symbols = NULL;
42 ld_plugin_get_symbols get_symbols = NULL;
43 ld_plugin_add_input_file add_input_file = NULL;
44 ld_plugin_add_input_library add_input_library = NULL;
45 ld_plugin_set_extra_library_path set_extra_library_path = NULL;
46 ld_plugin_message message = discard_message;
54 std::vector<ld_plugin_symbol> syms;
57 lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
58 std::string output_name = "";
59 std::list<claimed_file> Modules;
60 std::vector<sys::Path> Cleanup;
64 enum generate_bc { BC_NO, BC_ALSO, BC_ONLY };
65 static bool generate_api_file = false;
66 static generate_bc generate_bc_file = BC_NO;
67 static std::string bc_path;
68 static std::string as_path;
69 static std::vector<std::string> pass_through;
70 static std::string extra_library_path;
71 // Additional options to pass into the code generator.
72 // Note: This array will contain all plugin options which are not claimed
73 // as plugin exclusive to pass to the code generator.
74 // For example, "generate-api-file" and "as"options are for the plugin
75 // use only and will not be passed.
76 static std::vector<std::string> extra;
78 static void process_plugin_option(const char* opt_)
82 llvm::StringRef opt = opt_;
84 if (opt == "generate-api-file") {
85 generate_api_file = true;
86 } else if (opt.startswith("as=")) {
87 if (!as_path.empty()) {
88 (*message)(LDPL_WARNING, "Path to as specified twice. "
89 "Discarding %s", opt_);
91 as_path = opt.substr(strlen("as="));
93 } else if (opt.startswith("extra-library-path=")) {
94 extra_library_path = opt.substr(strlen("extra_library_path="));
95 } else if (opt.startswith("pass-through=")) {
96 llvm::StringRef item = opt.substr(strlen("pass-through="));
97 pass_through.push_back(item.str());
98 } else if (opt == "emit-llvm") {
99 generate_bc_file = BC_ONLY;
100 } else if (opt == "also-emit-llvm") {
101 generate_bc_file = BC_ALSO;
102 } else if (opt.startswith("also-emit-llvm=")) {
103 llvm::StringRef path = opt.substr(strlen("also-emit-llvm="));
104 generate_bc_file = BC_ALSO;
105 if (!bc_path.empty()) {
106 (*message)(LDPL_WARNING, "Path to the output IL file specified twice. "
107 "Discarding %s", opt_);
112 // Save this option to pass to the code generator.
113 extra.push_back(opt);
118 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
120 static ld_plugin_status all_symbols_read_hook(void);
121 static ld_plugin_status cleanup_hook(void);
123 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
124 ld_plugin_status onload(ld_plugin_tv *tv) {
125 // We're given a pointer to the first transfer vector. We read through them
126 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
127 // contain pointers to functions that we need to call to register our own
128 // hooks. The others are addresses of functions we can use to call into gold
131 bool registeredClaimFile = false;
133 for (; tv->tv_tag != LDPT_NULL; ++tv) {
134 switch (tv->tv_tag) {
135 case LDPT_API_VERSION:
136 api_version = tv->tv_u.tv_val;
138 case LDPT_GOLD_VERSION: // major * 100 + minor
139 gold_version = tv->tv_u.tv_val;
141 case LDPT_OUTPUT_NAME:
142 output_name = tv->tv_u.tv_string;
144 case LDPT_LINKER_OUTPUT:
145 switch (tv->tv_u.tv_val) {
147 case LDPO_DYN: // .so
148 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
150 case LDPO_EXEC: // .exe
151 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
154 (*message)(LDPL_ERROR, "Unknown output file type %d",
158 // TODO: add an option to disable PIC.
159 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
162 options::process_plugin_option(tv->tv_u.tv_string);
164 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
165 ld_plugin_register_claim_file callback;
166 callback = tv->tv_u.tv_register_claim_file;
168 if ((*callback)(claim_file_hook) != LDPS_OK)
171 registeredClaimFile = true;
173 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
174 ld_plugin_register_all_symbols_read callback;
175 callback = tv->tv_u.tv_register_all_symbols_read;
177 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
180 case LDPT_REGISTER_CLEANUP_HOOK: {
181 ld_plugin_register_cleanup callback;
182 callback = tv->tv_u.tv_register_cleanup;
184 if ((*callback)(cleanup_hook) != LDPS_OK)
187 case LDPT_ADD_SYMBOLS:
188 add_symbols = tv->tv_u.tv_add_symbols;
190 case LDPT_GET_SYMBOLS:
191 get_symbols = tv->tv_u.tv_get_symbols;
193 case LDPT_ADD_INPUT_FILE:
194 add_input_file = tv->tv_u.tv_add_input_file;
196 case LDPT_ADD_INPUT_LIBRARY:
197 add_input_library = tv->tv_u.tv_add_input_file;
199 case LDPT_SET_EXTRA_LIBRARY_PATH:
200 set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
203 message = tv->tv_u.tv_message;
210 if (!registeredClaimFile) {
211 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
215 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
222 /// claim_file_hook - called by gold to see whether this file is one that
223 /// our plugin can handle. We'll try to open it and register all the symbols
224 /// with add_symbol if possible.
225 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
229 // Gold has found what might be IR part-way inside of a file, such as
231 if (lseek(file->fd, file->offset, SEEK_SET) == -1) {
232 (*message)(LDPL_ERROR,
233 "Failed to seek to archive member of %s at offset %d: %s\n",
235 file->offset, sys::StrError(errno).c_str());
238 buf = malloc(file->filesize);
240 (*message)(LDPL_ERROR,
241 "Failed to allocate buffer for archive member of size: %d\n",
245 if (read(file->fd, buf, file->filesize) != file->filesize) {
246 (*message)(LDPL_ERROR,
247 "Failed to read archive member of %s at offset %d: %s\n",
250 sys::StrError(errno).c_str());
254 if (!lto_module_is_object_file_in_memory(buf, file->filesize)) {
258 } else if (!lto_module_is_object_file(file->name))
262 Modules.resize(Modules.size() + 1);
263 claimed_file &cf = Modules.back();
265 cf.M = buf ? lto_module_create_from_memory(buf, file->filesize) :
266 lto_module_create(file->name);
269 (*message)(LDPL_ERROR, "Failed to create LLVM module: %s",
270 lto_get_error_message());
273 cf.handle = file->handle;
274 unsigned sym_count = lto_module_get_num_symbols(cf.M);
275 cf.syms.reserve(sym_count);
277 for (unsigned i = 0; i != sym_count; ++i) {
278 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(cf.M, i);
279 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
282 cf.syms.push_back(ld_plugin_symbol());
283 ld_plugin_symbol &sym = cf.syms.back();
284 sym.name = const_cast<char *>(lto_module_get_symbol_name(cf.M, i));
287 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
289 case LTO_SYMBOL_SCOPE_HIDDEN:
290 sym.visibility = LDPV_HIDDEN;
292 case LTO_SYMBOL_SCOPE_PROTECTED:
293 sym.visibility = LDPV_PROTECTED;
296 case LTO_SYMBOL_SCOPE_DEFAULT:
297 sym.visibility = LDPV_DEFAULT;
300 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
304 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
305 switch (definition) {
306 case LTO_SYMBOL_DEFINITION_REGULAR:
309 case LTO_SYMBOL_DEFINITION_UNDEFINED:
310 sym.def = LDPK_UNDEF;
312 case LTO_SYMBOL_DEFINITION_TENTATIVE:
313 sym.def = LDPK_COMMON;
315 case LTO_SYMBOL_DEFINITION_WEAK:
316 sym.def = LDPK_WEAKDEF;
318 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
319 sym.def = LDPK_WEAKUNDEF;
322 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
326 // LLVM never emits COMDAT.
328 sym.comdat_key = NULL;
330 sym.resolution = LDPR_UNKNOWN;
333 cf.syms.reserve(cf.syms.size());
335 if (!cf.syms.empty()) {
336 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
337 (*message)(LDPL_ERROR, "Unable to add symbols!");
345 /// all_symbols_read_hook - gold informs us that all symbols have been read.
346 /// At this point, we use get_symbols to see if any of our definitions have
347 /// been overridden by a native object file. Then, perform optimization and
349 static ld_plugin_status all_symbols_read_hook(void) {
350 lto_code_gen_t cg = lto_codegen_create();
352 for (std::list<claimed_file>::iterator I = Modules.begin(),
353 E = Modules.end(); I != E; ++I)
354 lto_codegen_add_module(cg, I->M);
356 std::ofstream api_file;
357 if (options::generate_api_file) {
358 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
359 if (!api_file.is_open()) {
360 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
365 // If we don't preserve any symbols, libLTO will assume that all symbols are
366 // needed. Keep all symbols unless we're producing a final executable.
367 bool anySymbolsPreserved = false;
368 for (std::list<claimed_file>::iterator I = Modules.begin(),
369 E = Modules.end(); I != E; ++I) {
370 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
371 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
372 if (I->syms[i].resolution == LDPR_PREVAILING_DEF) {
373 lto_codegen_add_must_preserve_symbol(cg, I->syms[i].name);
374 anySymbolsPreserved = true;
376 if (options::generate_api_file)
377 api_file << I->syms[i].name << "\n";
382 if (options::generate_api_file)
385 if (!anySymbolsPreserved) {
386 // All of the IL is unnecessary!
387 lto_codegen_dispose(cg);
391 lto_codegen_set_pic_model(cg, output_type);
392 lto_codegen_set_debug_model(cg, LTO_DEBUG_MODEL_DWARF);
393 if (!options::as_path.empty()) {
394 sys::Path p = sys::Program::FindProgramByName(options::as_path);
395 lto_codegen_set_assembler_path(cg, p.c_str());
397 // Pass through extra options to the code generator.
398 if (!options::extra.empty()) {
399 for (std::vector<std::string>::iterator it = options::extra.begin();
400 it != options::extra.end(); ++it) {
401 lto_codegen_debug_options(cg, (*it).c_str());
406 if (options::generate_bc_file != options::BC_NO) {
408 if (options::generate_bc_file == options::BC_ONLY)
410 else if (!options::bc_path.empty())
411 path = options::bc_path;
413 path = output_name + ".bc";
414 bool err = lto_codegen_write_merged_modules(cg, path.c_str());
416 (*message)(LDPL_FATAL, "Failed to write the output file.");
417 if (options::generate_bc_file == options::BC_ONLY)
421 const char *buffer = static_cast<const char *>(lto_codegen_compile(cg,
426 sys::Path uniqueObjPath("/tmp/llvmgold.o");
427 if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) {
428 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
431 raw_fd_ostream objFile(uniqueObjPath.c_str(), ErrMsg,
432 raw_fd_ostream::F_Binary);
433 if (!ErrMsg.empty()) {
434 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
438 objFile.write(buffer, bufsize);
441 lto_codegen_dispose(cg);
443 if ((*add_input_file)(uniqueObjPath.c_str()) != LDPS_OK) {
444 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
445 (*message)(LDPL_ERROR, "File left behind in: %s", uniqueObjPath.c_str());
449 if (!options::extra_library_path.empty() &&
450 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) {
451 (*message)(LDPL_ERROR, "Unable to set the extra library path.");
455 for (std::vector<std::string>::iterator i = options::pass_through.begin(),
456 e = options::pass_through.end();
458 std::string &item = *i;
459 const char *item_p = item.c_str();
460 if (llvm::StringRef(item).startswith("-l")) {
461 if (add_input_library(item_p + 2) != LDPS_OK) {
462 (*message)(LDPL_ERROR, "Unable to add library to the link.");
466 if (add_input_file(item_p) != LDPS_OK) {
467 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
473 Cleanup.push_back(uniqueObjPath);
478 static ld_plugin_status cleanup_hook(void) {
481 for (int i = 0, e = Cleanup.size(); i != e; ++i)
482 if (Cleanup[i].eraseFromDisk(false, &ErrMsg))
483 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),