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;
132 bool registeredAllSymbolsRead = false;
133 bool registeredCleanup = false;
135 for (; tv->tv_tag != LDPT_NULL; ++tv) {
136 switch (tv->tv_tag) {
137 case LDPT_API_VERSION:
138 api_version = tv->tv_u.tv_val;
140 case LDPT_GOLD_VERSION: // major * 100 + minor
141 gold_version = tv->tv_u.tv_val;
143 case LDPT_OUTPUT_NAME:
144 output_name = tv->tv_u.tv_string;
146 case LDPT_LINKER_OUTPUT:
147 switch (tv->tv_u.tv_val) {
149 case LDPO_DYN: // .so
150 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
152 case LDPO_EXEC: // .exe
153 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
156 (*message)(LDPL_ERROR, "Unknown output file type %d",
160 // TODO: add an option to disable PIC.
161 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
164 options::process_plugin_option(tv->tv_u.tv_string);
166 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
167 ld_plugin_register_claim_file callback;
168 callback = tv->tv_u.tv_register_claim_file;
170 if ((*callback)(claim_file_hook) != LDPS_OK)
173 registeredClaimFile = true;
175 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
176 ld_plugin_register_all_symbols_read callback;
177 callback = tv->tv_u.tv_register_all_symbols_read;
179 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
182 registeredAllSymbolsRead = true;
184 case LDPT_REGISTER_CLEANUP_HOOK: {
185 ld_plugin_register_cleanup callback;
186 callback = tv->tv_u.tv_register_cleanup;
188 if ((*callback)(cleanup_hook) != LDPS_OK)
191 registeredCleanup = true;
193 case LDPT_ADD_SYMBOLS:
194 add_symbols = tv->tv_u.tv_add_symbols;
196 case LDPT_GET_SYMBOLS:
197 get_symbols = tv->tv_u.tv_get_symbols;
199 case LDPT_ADD_INPUT_FILE:
200 add_input_file = tv->tv_u.tv_add_input_file;
202 case LDPT_ADD_INPUT_LIBRARY:
203 add_input_library = tv->tv_u.tv_add_input_file;
205 case LDPT_SET_EXTRA_LIBRARY_PATH:
206 set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
209 message = tv->tv_u.tv_message;
216 if (!registeredClaimFile) {
217 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
221 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
228 /// claim_file_hook - called by gold to see whether this file is one that
229 /// our plugin can handle. We'll try to open it and register all the symbols
230 /// with add_symbol if possible.
231 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
235 // Gold has found what might be IR part-way inside of a file, such as
237 if (lseek(file->fd, file->offset, SEEK_SET) == -1) {
238 (*message)(LDPL_ERROR,
239 "Failed to seek to archive member of %s at offset %d: %s\n",
241 file->offset, sys::StrError(errno).c_str());
244 buf = malloc(file->filesize);
246 (*message)(LDPL_ERROR,
247 "Failed to allocate buffer for archive member of size: %d\n",
251 if (read(file->fd, buf, file->filesize) != file->filesize) {
252 (*message)(LDPL_ERROR,
253 "Failed to read archive member of %s at offset %d: %s\n",
256 sys::StrError(errno).c_str());
260 if (!lto_module_is_object_file_in_memory(buf, file->filesize)) {
264 } else if (!lto_module_is_object_file(file->name))
268 Modules.resize(Modules.size() + 1);
269 claimed_file &cf = Modules.back();
271 cf.M = buf ? lto_module_create_from_memory(buf, file->filesize) :
272 lto_module_create(file->name);
275 (*message)(LDPL_ERROR, "Failed to create LLVM module: %s",
276 lto_get_error_message());
279 cf.handle = file->handle;
280 unsigned sym_count = lto_module_get_num_symbols(cf.M);
281 cf.syms.reserve(sym_count);
283 for (unsigned i = 0; i != sym_count; ++i) {
284 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(cf.M, i);
285 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
288 cf.syms.push_back(ld_plugin_symbol());
289 ld_plugin_symbol &sym = cf.syms.back();
290 sym.name = const_cast<char *>(lto_module_get_symbol_name(cf.M, i));
293 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
295 case LTO_SYMBOL_SCOPE_HIDDEN:
296 sym.visibility = LDPV_HIDDEN;
298 case LTO_SYMBOL_SCOPE_PROTECTED:
299 sym.visibility = LDPV_PROTECTED;
302 case LTO_SYMBOL_SCOPE_DEFAULT:
303 sym.visibility = LDPV_DEFAULT;
306 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
310 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
311 switch (definition) {
312 case LTO_SYMBOL_DEFINITION_REGULAR:
315 case LTO_SYMBOL_DEFINITION_UNDEFINED:
316 sym.def = LDPK_UNDEF;
318 case LTO_SYMBOL_DEFINITION_TENTATIVE:
319 sym.def = LDPK_COMMON;
321 case LTO_SYMBOL_DEFINITION_WEAK:
322 sym.def = LDPK_WEAKDEF;
324 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
325 sym.def = LDPK_WEAKUNDEF;
328 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
332 // LLVM never emits COMDAT.
334 sym.comdat_key = NULL;
336 sym.resolution = LDPR_UNKNOWN;
339 cf.syms.reserve(cf.syms.size());
341 if (!cf.syms.empty()) {
342 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
343 (*message)(LDPL_ERROR, "Unable to add symbols!");
351 /// all_symbols_read_hook - gold informs us that all symbols have been read.
352 /// At this point, we use get_symbols to see if any of our definitions have
353 /// been overridden by a native object file. Then, perform optimization and
355 static ld_plugin_status all_symbols_read_hook(void) {
356 lto_code_gen_t cg = lto_codegen_create();
358 for (std::list<claimed_file>::iterator I = Modules.begin(),
359 E = Modules.end(); I != E; ++I)
360 lto_codegen_add_module(cg, I->M);
362 std::ofstream api_file;
363 if (options::generate_api_file) {
364 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
365 if (!api_file.is_open()) {
366 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
371 // If we don't preserve any symbols, libLTO will assume that all symbols are
372 // needed. Keep all symbols unless we're producing a final executable.
373 bool anySymbolsPreserved = false;
374 for (std::list<claimed_file>::iterator I = Modules.begin(),
375 E = Modules.end(); I != E; ++I) {
376 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
377 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
378 if (I->syms[i].resolution == LDPR_PREVAILING_DEF) {
379 lto_codegen_add_must_preserve_symbol(cg, I->syms[i].name);
380 anySymbolsPreserved = true;
382 if (options::generate_api_file)
383 api_file << I->syms[i].name << "\n";
388 if (options::generate_api_file)
391 if (!anySymbolsPreserved) {
392 // All of the IL is unnecessary!
393 lto_codegen_dispose(cg);
397 lto_codegen_set_pic_model(cg, output_type);
398 lto_codegen_set_debug_model(cg, LTO_DEBUG_MODEL_DWARF);
399 if (!options::as_path.empty()) {
400 sys::Path p = sys::Program::FindProgramByName(options::as_path);
401 lto_codegen_set_assembler_path(cg, p.c_str());
403 // Pass through extra options to the code generator.
404 if (!options::extra.empty()) {
405 for (std::vector<std::string>::iterator it = options::extra.begin();
406 it != options::extra.end(); ++it) {
407 lto_codegen_debug_options(cg, (*it).c_str());
412 if (options::generate_bc_file != options::BC_NO) {
414 if (options::generate_bc_file == options::BC_ONLY)
416 else if (!options::bc_path.empty())
417 path = options::bc_path;
419 path = output_name + ".bc";
420 bool err = lto_codegen_write_merged_modules(cg, path.c_str());
422 (*message)(LDPL_FATAL, "Failed to write the output file.");
423 if (options::generate_bc_file == options::BC_ONLY)
427 const char *buffer = static_cast<const char *>(lto_codegen_compile(cg,
432 sys::Path uniqueObjPath("/tmp/llvmgold.o");
433 if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) {
434 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
437 raw_fd_ostream objFile(uniqueObjPath.c_str(), ErrMsg,
438 raw_fd_ostream::F_Binary);
439 if (!ErrMsg.empty()) {
440 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
444 objFile.write(buffer, bufsize);
447 lto_codegen_dispose(cg);
449 if ((*add_input_file)(uniqueObjPath.c_str()) != LDPS_OK) {
450 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
451 (*message)(LDPL_ERROR, "File left behind in: %s", uniqueObjPath.c_str());
455 if (!options::extra_library_path.empty() &&
456 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) {
457 (*message)(LDPL_ERROR, "Unable to set the extra library path.");
461 for (std::vector<std::string>::iterator i = options::pass_through.begin(),
462 e = options::pass_through.end();
464 std::string &item = *i;
465 const char *item_p = item.c_str();
466 if (llvm::StringRef(item).startswith("-l")) {
467 if (add_input_library(item_p + 2) != LDPS_OK) {
468 (*message)(LDPL_ERROR, "Unable to add library to the link.");
472 if (add_input_file(item_p) != LDPS_OK) {
473 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
479 Cleanup.push_back(uniqueObjPath);
484 static ld_plugin_status cleanup_hook(void) {
487 for (int i = 0, e = Cleanup.size(); i != e; ++i)
488 if (Cleanup[i].eraseFromDisk(false, &ErrMsg))
489 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),