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 static std::string triple;
72 // Additional options to pass into the code generator.
73 // Note: This array will contain all plugin options which are not claimed
74 // as plugin exclusive to pass to the code generator.
75 // For example, "generate-api-file" and "as"options are for the plugin
76 // use only and will not be passed.
77 static std::vector<std::string> extra;
79 static void process_plugin_option(const char* opt_)
83 llvm::StringRef opt = opt_;
85 if (opt == "generate-api-file") {
86 generate_api_file = true;
87 } else if (opt.startswith("as=")) {
88 if (!as_path.empty()) {
89 (*message)(LDPL_WARNING, "Path to as specified twice. "
90 "Discarding %s", opt_);
92 as_path = opt.substr(strlen("as="));
94 } else if (opt.startswith("extra-library-path=")) {
95 extra_library_path = opt.substr(strlen("extra_library_path="));
96 } else if (opt.startswith("pass-through=")) {
97 llvm::StringRef item = opt.substr(strlen("pass-through="));
98 pass_through.push_back(item.str());
99 } else if (opt == "mtriple=") {
100 triple = opt.substr(strlen("mtriple="));
101 } else if (opt == "emit-llvm") {
102 generate_bc_file = BC_ONLY;
103 } else if (opt == "also-emit-llvm") {
104 generate_bc_file = BC_ALSO;
105 } else if (opt.startswith("also-emit-llvm=")) {
106 llvm::StringRef path = opt.substr(strlen("also-emit-llvm="));
107 generate_bc_file = BC_ALSO;
108 if (!bc_path.empty()) {
109 (*message)(LDPL_WARNING, "Path to the output IL file specified twice. "
110 "Discarding %s", opt_);
115 // Save this option to pass to the code generator.
116 extra.push_back(opt);
121 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
123 static ld_plugin_status all_symbols_read_hook(void);
124 static ld_plugin_status cleanup_hook(void);
126 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
127 ld_plugin_status onload(ld_plugin_tv *tv) {
128 // We're given a pointer to the first transfer vector. We read through them
129 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
130 // contain pointers to functions that we need to call to register our own
131 // hooks. The others are addresses of functions we can use to call into gold
134 bool registeredClaimFile = false;
136 for (; tv->tv_tag != LDPT_NULL; ++tv) {
137 switch (tv->tv_tag) {
138 case LDPT_API_VERSION:
139 api_version = tv->tv_u.tv_val;
141 case LDPT_GOLD_VERSION: // major * 100 + minor
142 gold_version = tv->tv_u.tv_val;
144 case LDPT_OUTPUT_NAME:
145 output_name = tv->tv_u.tv_string;
147 case LDPT_LINKER_OUTPUT:
148 switch (tv->tv_u.tv_val) {
150 case LDPO_DYN: // .so
151 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
153 case LDPO_EXEC: // .exe
154 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
157 (*message)(LDPL_ERROR, "Unknown output file type %d",
161 // TODO: add an option to disable PIC.
162 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
165 options::process_plugin_option(tv->tv_u.tv_string);
167 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
168 ld_plugin_register_claim_file callback;
169 callback = tv->tv_u.tv_register_claim_file;
171 if ((*callback)(claim_file_hook) != LDPS_OK)
174 registeredClaimFile = true;
176 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
177 ld_plugin_register_all_symbols_read callback;
178 callback = tv->tv_u.tv_register_all_symbols_read;
180 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
183 case LDPT_REGISTER_CLEANUP_HOOK: {
184 ld_plugin_register_cleanup callback;
185 callback = tv->tv_u.tv_register_cleanup;
187 if ((*callback)(cleanup_hook) != LDPS_OK)
190 case LDPT_ADD_SYMBOLS:
191 add_symbols = tv->tv_u.tv_add_symbols;
193 case LDPT_GET_SYMBOLS:
194 get_symbols = tv->tv_u.tv_get_symbols;
196 case LDPT_ADD_INPUT_FILE:
197 add_input_file = tv->tv_u.tv_add_input_file;
199 case LDPT_ADD_INPUT_LIBRARY:
200 add_input_library = tv->tv_u.tv_add_input_file;
202 case LDPT_SET_EXTRA_LIBRARY_PATH:
203 set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
206 message = tv->tv_u.tv_message;
213 if (!registeredClaimFile) {
214 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
218 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
225 /// claim_file_hook - called by gold to see whether this file is one that
226 /// our plugin can handle. We'll try to open it and register all the symbols
227 /// with add_symbol if possible.
228 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
232 // Gold has found what might be IR part-way inside of a file, such as
234 if (lseek(file->fd, file->offset, SEEK_SET) == -1) {
235 (*message)(LDPL_ERROR,
236 "Failed to seek to archive member of %s at offset %d: %s\n",
238 file->offset, sys::StrError(errno).c_str());
241 buf = malloc(file->filesize);
243 (*message)(LDPL_ERROR,
244 "Failed to allocate buffer for archive member of size: %d\n",
248 if (read(file->fd, buf, file->filesize) != file->filesize) {
249 (*message)(LDPL_ERROR,
250 "Failed to read archive member of %s at offset %d: %s\n",
253 sys::StrError(errno).c_str());
257 if (!lto_module_is_object_file_in_memory(buf, file->filesize)) {
261 } else if (!lto_module_is_object_file(file->name))
265 Modules.resize(Modules.size() + 1);
266 claimed_file &cf = Modules.back();
268 cf.M = buf ? lto_module_create_from_memory(buf, file->filesize) :
269 lto_module_create(file->name);
272 (*message)(LDPL_ERROR, "Failed to create LLVM module: %s",
273 lto_get_error_message());
277 if (!options::triple.empty())
278 lto_module_set_target_triple(cf.M, options::triple.c_str());
280 cf.handle = file->handle;
281 unsigned sym_count = lto_module_get_num_symbols(cf.M);
282 cf.syms.reserve(sym_count);
284 for (unsigned i = 0; i != sym_count; ++i) {
285 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(cf.M, i);
286 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
289 cf.syms.push_back(ld_plugin_symbol());
290 ld_plugin_symbol &sym = cf.syms.back();
291 sym.name = const_cast<char *>(lto_module_get_symbol_name(cf.M, i));
294 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
296 case LTO_SYMBOL_SCOPE_HIDDEN:
297 sym.visibility = LDPV_HIDDEN;
299 case LTO_SYMBOL_SCOPE_PROTECTED:
300 sym.visibility = LDPV_PROTECTED;
303 case LTO_SYMBOL_SCOPE_DEFAULT:
304 sym.visibility = LDPV_DEFAULT;
307 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
311 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
312 switch (definition) {
313 case LTO_SYMBOL_DEFINITION_REGULAR:
316 case LTO_SYMBOL_DEFINITION_UNDEFINED:
317 sym.def = LDPK_UNDEF;
319 case LTO_SYMBOL_DEFINITION_TENTATIVE:
320 sym.def = LDPK_COMMON;
322 case LTO_SYMBOL_DEFINITION_WEAK:
323 sym.def = LDPK_WEAKDEF;
325 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
326 sym.def = LDPK_WEAKUNDEF;
329 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
333 // LLVM never emits COMDAT.
335 sym.comdat_key = NULL;
337 sym.resolution = LDPR_UNKNOWN;
340 cf.syms.reserve(cf.syms.size());
342 if (!cf.syms.empty()) {
343 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
344 (*message)(LDPL_ERROR, "Unable to add symbols!");
352 /// all_symbols_read_hook - gold informs us that all symbols have been read.
353 /// At this point, we use get_symbols to see if any of our definitions have
354 /// been overridden by a native object file. Then, perform optimization and
356 static ld_plugin_status all_symbols_read_hook(void) {
357 lto_code_gen_t cg = lto_codegen_create();
359 for (std::list<claimed_file>::iterator I = Modules.begin(),
360 E = Modules.end(); I != E; ++I)
361 lto_codegen_add_module(cg, I->M);
363 std::ofstream api_file;
364 if (options::generate_api_file) {
365 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
366 if (!api_file.is_open()) {
367 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
372 // If we don't preserve any symbols, libLTO will assume that all symbols are
373 // needed. Keep all symbols unless we're producing a final executable.
374 bool anySymbolsPreserved = false;
375 for (std::list<claimed_file>::iterator I = Modules.begin(),
376 E = Modules.end(); I != E; ++I) {
377 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
378 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
379 if (I->syms[i].resolution == LDPR_PREVAILING_DEF) {
380 lto_codegen_add_must_preserve_symbol(cg, I->syms[i].name);
381 anySymbolsPreserved = true;
383 if (options::generate_api_file)
384 api_file << I->syms[i].name << "\n";
389 if (options::generate_api_file)
392 if (!anySymbolsPreserved) {
393 // All of the IL is unnecessary!
394 lto_codegen_dispose(cg);
398 lto_codegen_set_pic_model(cg, output_type);
399 lto_codegen_set_debug_model(cg, LTO_DEBUG_MODEL_DWARF);
400 if (!options::as_path.empty()) {
401 sys::Path p = sys::Program::FindProgramByName(options::as_path);
402 lto_codegen_set_assembler_path(cg, p.c_str());
404 // Pass through extra options to the code generator.
405 if (!options::extra.empty()) {
406 for (std::vector<std::string>::iterator it = options::extra.begin();
407 it != options::extra.end(); ++it) {
408 lto_codegen_debug_options(cg, (*it).c_str());
413 if (options::generate_bc_file != options::BC_NO) {
415 if (options::generate_bc_file == options::BC_ONLY)
417 else if (!options::bc_path.empty())
418 path = options::bc_path;
420 path = output_name + ".bc";
421 bool err = lto_codegen_write_merged_modules(cg, path.c_str());
423 (*message)(LDPL_FATAL, "Failed to write the output file.");
424 if (options::generate_bc_file == options::BC_ONLY)
428 const char *buffer = static_cast<const char *>(lto_codegen_compile(cg,
433 sys::Path uniqueObjPath("/tmp/llvmgold.o");
434 if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) {
435 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
438 raw_fd_ostream objFile(uniqueObjPath.c_str(), ErrMsg,
439 raw_fd_ostream::F_Binary);
440 if (!ErrMsg.empty()) {
441 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
445 objFile.write(buffer, bufsize);
448 lto_codegen_dispose(cg);
450 if ((*add_input_file)(uniqueObjPath.c_str()) != LDPS_OK) {
451 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
452 (*message)(LDPL_ERROR, "File left behind in: %s", uniqueObjPath.c_str());
456 if (!options::extra_library_path.empty() &&
457 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) {
458 (*message)(LDPL_ERROR, "Unable to set the extra library path.");
462 for (std::vector<std::string>::iterator i = options::pass_through.begin(),
463 e = options::pass_through.end();
465 std::string &item = *i;
466 const char *item_p = item.c_str();
467 if (llvm::StringRef(item).startswith("-l")) {
468 if (add_input_library(item_p + 2) != LDPS_OK) {
469 (*message)(LDPL_ERROR, "Unable to add library to the link.");
473 if (add_input_file(item_p) != LDPS_OK) {
474 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
480 Cleanup.push_back(uniqueObjPath);
485 static ld_plugin_status cleanup_hook(void) {
488 for (int i = 0, e = Cleanup.size(); i != e; ++i)
489 if (Cleanup[i].eraseFromDisk(false, &ErrMsg))
490 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),