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> as_args;
70 static std::vector<std::string> pass_through;
71 static std::string extra_library_path;
72 static std::string triple;
73 // Additional options to pass into the code generator.
74 // Note: This array will contain all plugin options which are not claimed
75 // as plugin exclusive to pass to the code generator.
76 // For example, "generate-api-file" and "as"options are for the plugin
77 // use only and will not be passed.
78 static std::vector<std::string> extra;
80 static void process_plugin_option(const char* opt_)
84 llvm::StringRef opt = opt_;
86 if (opt == "generate-api-file") {
87 generate_api_file = true;
88 } else if (opt.startswith("as=")) {
89 if (!as_path.empty()) {
90 (*message)(LDPL_WARNING, "Path to as specified twice. "
91 "Discarding %s", opt_);
93 as_path = opt.substr(strlen("as="));
95 } else if (opt.startswith("as-arg=")) {
96 llvm::StringRef item = opt.substr(strlen("as-arg="));
97 as_args.push_back(item.str());
98 } else if (opt.startswith("extra-library-path=")) {
99 extra_library_path = opt.substr(strlen("extra_library_path="));
100 } else if (opt.startswith("pass-through=")) {
101 llvm::StringRef item = opt.substr(strlen("pass-through="));
102 pass_through.push_back(item.str());
103 } else if (opt.startswith("mtriple=")) {
104 triple = opt.substr(strlen("mtriple="));
105 } else if (opt == "emit-llvm") {
106 generate_bc_file = BC_ONLY;
107 } else if (opt == "also-emit-llvm") {
108 generate_bc_file = BC_ALSO;
109 } else if (opt.startswith("also-emit-llvm=")) {
110 llvm::StringRef path = opt.substr(strlen("also-emit-llvm="));
111 generate_bc_file = BC_ALSO;
112 if (!bc_path.empty()) {
113 (*message)(LDPL_WARNING, "Path to the output IL file specified twice. "
114 "Discarding %s", opt_);
119 // Save this option to pass to the code generator.
120 extra.push_back(opt);
125 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
127 static ld_plugin_status all_symbols_read_hook(void);
128 static ld_plugin_status cleanup_hook(void);
130 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
131 ld_plugin_status onload(ld_plugin_tv *tv) {
132 // We're given a pointer to the first transfer vector. We read through them
133 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
134 // contain pointers to functions that we need to call to register our own
135 // hooks. The others are addresses of functions we can use to call into gold
138 bool registeredClaimFile = false;
140 for (; tv->tv_tag != LDPT_NULL; ++tv) {
141 switch (tv->tv_tag) {
142 case LDPT_API_VERSION:
143 api_version = tv->tv_u.tv_val;
145 case LDPT_GOLD_VERSION: // major * 100 + minor
146 gold_version = tv->tv_u.tv_val;
148 case LDPT_OUTPUT_NAME:
149 output_name = tv->tv_u.tv_string;
151 case LDPT_LINKER_OUTPUT:
152 switch (tv->tv_u.tv_val) {
154 case LDPO_DYN: // .so
155 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
157 case LDPO_EXEC: // .exe
158 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
161 (*message)(LDPL_ERROR, "Unknown output file type %d",
165 // TODO: add an option to disable PIC.
166 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
169 options::process_plugin_option(tv->tv_u.tv_string);
171 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
172 ld_plugin_register_claim_file callback;
173 callback = tv->tv_u.tv_register_claim_file;
175 if ((*callback)(claim_file_hook) != LDPS_OK)
178 registeredClaimFile = true;
180 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
181 ld_plugin_register_all_symbols_read callback;
182 callback = tv->tv_u.tv_register_all_symbols_read;
184 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
187 case LDPT_REGISTER_CLEANUP_HOOK: {
188 ld_plugin_register_cleanup callback;
189 callback = tv->tv_u.tv_register_cleanup;
191 if ((*callback)(cleanup_hook) != LDPS_OK)
194 case LDPT_ADD_SYMBOLS:
195 add_symbols = tv->tv_u.tv_add_symbols;
197 case LDPT_GET_SYMBOLS:
198 get_symbols = tv->tv_u.tv_get_symbols;
200 case LDPT_ADD_INPUT_FILE:
201 add_input_file = tv->tv_u.tv_add_input_file;
203 case LDPT_ADD_INPUT_LIBRARY:
204 add_input_library = tv->tv_u.tv_add_input_file;
206 case LDPT_SET_EXTRA_LIBRARY_PATH:
207 set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
210 message = tv->tv_u.tv_message;
217 if (!registeredClaimFile) {
218 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
222 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
229 /// claim_file_hook - called by gold to see whether this file is one that
230 /// our plugin can handle. We'll try to open it and register all the symbols
231 /// with add_symbol if possible.
232 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
236 // Gold has found what might be IR part-way inside of a file, such as
238 if (lseek(file->fd, file->offset, SEEK_SET) == -1) {
239 (*message)(LDPL_ERROR,
240 "Failed to seek to archive member of %s at offset %d: %s\n",
242 file->offset, sys::StrError(errno).c_str());
245 buf = malloc(file->filesize);
247 (*message)(LDPL_ERROR,
248 "Failed to allocate buffer for archive member of size: %d\n",
252 if (read(file->fd, buf, file->filesize) != file->filesize) {
253 (*message)(LDPL_ERROR,
254 "Failed to read archive member of %s at offset %d: %s\n",
257 sys::StrError(errno).c_str());
261 if (!lto_module_is_object_file_in_memory(buf, file->filesize)) {
265 } else if (!lto_module_is_object_file(file->name))
269 Modules.resize(Modules.size() + 1);
270 claimed_file &cf = Modules.back();
272 cf.M = buf ? lto_module_create_from_memory(buf, file->filesize) :
273 lto_module_create(file->name);
276 (*message)(LDPL_ERROR, "Failed to create LLVM module: %s",
277 lto_get_error_message());
281 if (!options::triple.empty())
282 lto_module_set_target_triple(cf.M, options::triple.c_str());
284 cf.handle = file->handle;
285 unsigned sym_count = lto_module_get_num_symbols(cf.M);
286 cf.syms.reserve(sym_count);
288 for (unsigned i = 0; i != sym_count; ++i) {
289 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(cf.M, i);
290 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
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(cf.M, i));
298 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
300 case LTO_SYMBOL_SCOPE_HIDDEN:
301 sym.visibility = LDPV_HIDDEN;
303 case LTO_SYMBOL_SCOPE_PROTECTED:
304 sym.visibility = LDPV_PROTECTED;
307 case LTO_SYMBOL_SCOPE_DEFAULT:
308 sym.visibility = LDPV_DEFAULT;
311 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
315 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
316 switch (definition) {
317 case LTO_SYMBOL_DEFINITION_REGULAR:
320 case LTO_SYMBOL_DEFINITION_UNDEFINED:
321 sym.def = LDPK_UNDEF;
323 case LTO_SYMBOL_DEFINITION_TENTATIVE:
324 sym.def = LDPK_COMMON;
326 case LTO_SYMBOL_DEFINITION_WEAK:
327 sym.def = LDPK_WEAKDEF;
329 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
330 sym.def = LDPK_WEAKUNDEF;
333 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
337 // LLVM never emits COMDAT.
339 sym.comdat_key = NULL;
341 sym.resolution = LDPR_UNKNOWN;
344 cf.syms.reserve(cf.syms.size());
346 if (!cf.syms.empty()) {
347 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
348 (*message)(LDPL_ERROR, "Unable to add symbols!");
356 /// all_symbols_read_hook - gold informs us that all symbols have been read.
357 /// At this point, we use get_symbols to see if any of our definitions have
358 /// been overridden by a native object file. Then, perform optimization and
360 static ld_plugin_status all_symbols_read_hook(void) {
361 lto_code_gen_t cg = lto_codegen_create();
363 for (std::list<claimed_file>::iterator I = Modules.begin(),
364 E = Modules.end(); I != E; ++I)
365 lto_codegen_add_module(cg, I->M);
367 std::ofstream api_file;
368 if (options::generate_api_file) {
369 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
370 if (!api_file.is_open()) {
371 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
376 // If we don't preserve any symbols, libLTO will assume that all symbols are
377 // needed. Keep all symbols unless we're producing a final executable.
378 bool anySymbolsPreserved = false;
379 for (std::list<claimed_file>::iterator I = Modules.begin(),
380 E = Modules.end(); I != E; ++I) {
381 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
382 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
383 if (I->syms[i].resolution == LDPR_PREVAILING_DEF) {
384 lto_codegen_add_must_preserve_symbol(cg, I->syms[i].name);
385 anySymbolsPreserved = true;
387 if (options::generate_api_file)
388 api_file << I->syms[i].name << "\n";
393 if (options::generate_api_file)
396 if (!anySymbolsPreserved) {
397 // All of the IL is unnecessary!
398 lto_codegen_dispose(cg);
402 lto_codegen_set_pic_model(cg, output_type);
403 lto_codegen_set_debug_model(cg, LTO_DEBUG_MODEL_DWARF);
404 if (!options::as_path.empty()) {
405 sys::Path p = sys::Program::FindProgramByName(options::as_path);
406 lto_codegen_set_assembler_path(cg, p.c_str());
408 if (!options::as_args.empty()) {
409 std::vector<const char *> as_args_p;
410 for (std::vector<std::string>::iterator I = options::as_args.begin(),
411 E = options::as_args.end(); I != E; ++I) {
412 as_args_p.push_back(I->c_str());
414 lto_codegen_set_assembler_args(cg, &as_args_p[0], as_args_p.size());
416 // Pass through extra options to the code generator.
417 if (!options::extra.empty()) {
418 for (std::vector<std::string>::iterator it = options::extra.begin();
419 it != options::extra.end(); ++it) {
420 lto_codegen_debug_options(cg, (*it).c_str());
425 if (options::generate_bc_file != options::BC_NO) {
427 if (options::generate_bc_file == options::BC_ONLY)
429 else if (!options::bc_path.empty())
430 path = options::bc_path;
432 path = output_name + ".bc";
433 bool err = lto_codegen_write_merged_modules(cg, path.c_str());
435 (*message)(LDPL_FATAL, "Failed to write the output file.");
436 if (options::generate_bc_file == options::BC_ONLY)
440 const char *buffer = static_cast<const char *>(lto_codegen_compile(cg,
445 sys::Path uniqueObjPath("/tmp/llvmgold.o");
446 if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) {
447 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
450 raw_fd_ostream objFile(uniqueObjPath.c_str(), ErrMsg,
451 raw_fd_ostream::F_Binary);
452 if (!ErrMsg.empty()) {
453 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
457 objFile.write(buffer, bufsize);
460 lto_codegen_dispose(cg);
462 if ((*add_input_file)(uniqueObjPath.c_str()) != LDPS_OK) {
463 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
464 (*message)(LDPL_ERROR, "File left behind in: %s", uniqueObjPath.c_str());
468 if (!options::extra_library_path.empty() &&
469 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) {
470 (*message)(LDPL_ERROR, "Unable to set the extra library path.");
474 for (std::vector<std::string>::iterator i = options::pass_through.begin(),
475 e = options::pass_through.end();
477 std::string &item = *i;
478 const char *item_p = item.c_str();
479 if (llvm::StringRef(item).startswith("-l")) {
480 if (add_input_library(item_p + 2) != LDPS_OK) {
481 (*message)(LDPL_ERROR, "Unable to add library to the link.");
485 if (add_input_file(item_p) != LDPS_OK) {
486 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
492 Cleanup.push_back(uniqueObjPath);
497 static ld_plugin_status cleanup_hook(void) {
500 for (int i = 0, e = Cleanup.size(); i != e; ++i)
501 if (Cleanup[i].eraseFromDisk(false, &ErrMsg))
502 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),