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_message message = discard_message;
52 std::vector<ld_plugin_symbol> syms;
55 lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
56 std::string output_name = "";
57 std::list<claimed_file> Modules;
58 std::vector<sys::Path> Cleanup;
62 enum generate_bc { BC_NO, BC_ALSO, BC_ONLY };
63 static bool generate_api_file = false;
64 static generate_bc generate_bc_file = BC_NO;
65 static std::string bc_path;
66 static std::string as_path;
67 // Additional options to pass into the code generator.
68 // Note: This array will contain all plugin options which are not claimed
69 // as plugin exclusive to pass to the code generator.
70 // For example, "generate-api-file" and "as"options are for the plugin
71 // use only and will not be passed.
72 static std::vector<std::string> extra;
74 static void process_plugin_option(const char* opt_)
78 llvm::StringRef opt = opt_;
80 if (opt == "generate-api-file") {
81 generate_api_file = true;
82 } else if (opt.startswith("as=")) {
83 if (!as_path.empty()) {
84 (*message)(LDPL_WARNING, "Path to as specified twice. "
85 "Discarding %s", opt_);
87 as_path = opt.substr(strlen("as="));
89 } else if (opt == "emit-llvm") {
90 generate_bc_file = BC_ONLY;
91 } else if (opt == "also-emit-llvm") {
92 generate_bc_file = BC_ALSO;
93 } else if (opt.startswith("also-emit-llvm=")) {
94 llvm::StringRef path = opt.substr(strlen("also-emit-llvm="));
95 generate_bc_file = BC_ALSO;
96 if (!bc_path.empty()) {
97 (*message)(LDPL_WARNING, "Path to the output IL file specified twice. "
98 "Discarding %s", opt_);
103 // Save this option to pass to the code generator.
104 extra.push_back(opt);
109 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
111 static ld_plugin_status all_symbols_read_hook(void);
112 static ld_plugin_status cleanup_hook(void);
114 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
115 ld_plugin_status onload(ld_plugin_tv *tv) {
116 // We're given a pointer to the first transfer vector. We read through them
117 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
118 // contain pointers to functions that we need to call to register our own
119 // hooks. The others are addresses of functions we can use to call into gold
122 bool registeredClaimFile = false;
123 bool registeredAllSymbolsRead = false;
124 bool registeredCleanup = false;
126 for (; tv->tv_tag != LDPT_NULL; ++tv) {
127 switch (tv->tv_tag) {
128 case LDPT_API_VERSION:
129 api_version = tv->tv_u.tv_val;
131 case LDPT_GOLD_VERSION: // major * 100 + minor
132 gold_version = tv->tv_u.tv_val;
134 case LDPT_OUTPUT_NAME:
135 output_name = tv->tv_u.tv_string;
137 case LDPT_LINKER_OUTPUT:
138 switch (tv->tv_u.tv_val) {
140 case LDPO_DYN: // .so
141 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
143 case LDPO_EXEC: // .exe
144 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
147 (*message)(LDPL_ERROR, "Unknown output file type %d",
151 // TODO: add an option to disable PIC.
152 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
155 options::process_plugin_option(tv->tv_u.tv_string);
157 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
158 ld_plugin_register_claim_file callback;
159 callback = tv->tv_u.tv_register_claim_file;
161 if ((*callback)(claim_file_hook) != LDPS_OK)
164 registeredClaimFile = true;
166 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
167 ld_plugin_register_all_symbols_read callback;
168 callback = tv->tv_u.tv_register_all_symbols_read;
170 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
173 registeredAllSymbolsRead = true;
175 case LDPT_REGISTER_CLEANUP_HOOK: {
176 ld_plugin_register_cleanup callback;
177 callback = tv->tv_u.tv_register_cleanup;
179 if ((*callback)(cleanup_hook) != LDPS_OK)
182 registeredCleanup = true;
184 case LDPT_ADD_SYMBOLS:
185 add_symbols = tv->tv_u.tv_add_symbols;
187 case LDPT_GET_SYMBOLS:
188 get_symbols = tv->tv_u.tv_get_symbols;
190 case LDPT_ADD_INPUT_FILE:
191 add_input_file = tv->tv_u.tv_add_input_file;
194 message = tv->tv_u.tv_message;
201 if (!registeredClaimFile) {
202 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
206 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
213 /// claim_file_hook - called by gold to see whether this file is one that
214 /// our plugin can handle. We'll try to open it and register all the symbols
215 /// with add_symbol if possible.
216 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
220 // Gold has found what might be IR part-way inside of a file, such as
222 if (lseek(file->fd, file->offset, SEEK_SET) == -1) {
223 (*message)(LDPL_ERROR,
224 "Failed to seek to archive member of %s at offset %d: %s\n",
226 file->offset, sys::StrError(errno).c_str());
229 buf = malloc(file->filesize);
231 (*message)(LDPL_ERROR,
232 "Failed to allocate buffer for archive member of size: %d\n",
236 if (read(file->fd, buf, file->filesize) != file->filesize) {
237 (*message)(LDPL_ERROR,
238 "Failed to read archive member of %s at offset %d: %s\n",
241 sys::StrError(errno).c_str());
245 if (!lto_module_is_object_file_in_memory(buf, file->filesize)) {
249 } else if (!lto_module_is_object_file(file->name))
253 Modules.resize(Modules.size() + 1);
254 claimed_file &cf = Modules.back();
256 cf.M = buf ? lto_module_create_from_memory(buf, file->filesize) :
257 lto_module_create(file->name);
260 (*message)(LDPL_ERROR, "Failed to create LLVM module: %s",
261 lto_get_error_message());
264 cf.handle = file->handle;
265 unsigned sym_count = lto_module_get_num_symbols(cf.M);
266 cf.syms.reserve(sym_count);
268 for (unsigned i = 0; i != sym_count; ++i) {
269 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(cf.M, i);
270 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
273 cf.syms.push_back(ld_plugin_symbol());
274 ld_plugin_symbol &sym = cf.syms.back();
275 sym.name = const_cast<char *>(lto_module_get_symbol_name(cf.M, i));
278 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
280 case LTO_SYMBOL_SCOPE_HIDDEN:
281 sym.visibility = LDPV_HIDDEN;
283 case LTO_SYMBOL_SCOPE_PROTECTED:
284 sym.visibility = LDPV_PROTECTED;
287 case LTO_SYMBOL_SCOPE_DEFAULT:
288 sym.visibility = LDPV_DEFAULT;
291 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
295 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
296 switch (definition) {
297 case LTO_SYMBOL_DEFINITION_REGULAR:
300 case LTO_SYMBOL_DEFINITION_UNDEFINED:
301 sym.def = LDPK_UNDEF;
303 case LTO_SYMBOL_DEFINITION_TENTATIVE:
304 sym.def = LDPK_COMMON;
306 case LTO_SYMBOL_DEFINITION_WEAK:
307 sym.def = LDPK_WEAKDEF;
309 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
310 sym.def = LDPK_WEAKUNDEF;
313 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
317 // LLVM never emits COMDAT.
319 sym.comdat_key = NULL;
321 sym.resolution = LDPR_UNKNOWN;
324 cf.syms.reserve(cf.syms.size());
326 if (!cf.syms.empty()) {
327 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
328 (*message)(LDPL_ERROR, "Unable to add symbols!");
336 /// all_symbols_read_hook - gold informs us that all symbols have been read.
337 /// At this point, we use get_symbols to see if any of our definitions have
338 /// been overridden by a native object file. Then, perform optimization and
340 static ld_plugin_status all_symbols_read_hook(void) {
341 lto_code_gen_t cg = lto_codegen_create();
343 for (std::list<claimed_file>::iterator I = Modules.begin(),
344 E = Modules.end(); I != E; ++I)
345 lto_codegen_add_module(cg, I->M);
347 std::ofstream api_file;
348 if (options::generate_api_file) {
349 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
350 if (!api_file.is_open()) {
351 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
356 // If we don't preserve any symbols, libLTO will assume that all symbols are
357 // needed. Keep all symbols unless we're producing a final executable.
358 bool anySymbolsPreserved = false;
359 for (std::list<claimed_file>::iterator I = Modules.begin(),
360 E = Modules.end(); I != E; ++I) {
361 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
362 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
363 if (I->syms[i].resolution == LDPR_PREVAILING_DEF) {
364 lto_codegen_add_must_preserve_symbol(cg, I->syms[i].name);
365 anySymbolsPreserved = true;
367 if (options::generate_api_file)
368 api_file << I->syms[i].name << "\n";
372 if (options::generate_api_file)
375 if (!anySymbolsPreserved) {
376 // This entire file is unnecessary!
377 lto_codegen_dispose(cg);
382 lto_codegen_set_pic_model(cg, output_type);
383 lto_codegen_set_debug_model(cg, LTO_DEBUG_MODEL_DWARF);
384 if (!options::as_path.empty()) {
385 sys::Path p = sys::Program::FindProgramByName(options::as_path);
386 lto_codegen_set_assembler_path(cg, p.c_str());
388 // Pass through extra options to the code generator.
389 if (!options::extra.empty()) {
390 for (std::vector<std::string>::iterator it = options::extra.begin();
391 it != options::extra.end(); ++it) {
392 lto_codegen_debug_options(cg, (*it).c_str());
397 if (options::generate_bc_file != options::BC_NO) {
399 if (options::generate_bc_file == options::BC_ONLY)
401 else if (!options::bc_path.empty())
402 path = options::bc_path;
404 path = output_name + ".bc";
405 bool err = lto_codegen_write_merged_modules(cg, path.c_str());
407 (*message)(LDPL_FATAL, "Failed to write the output file.");
408 if (options::generate_bc_file == options::BC_ONLY)
412 const char *buffer = static_cast<const char *>(lto_codegen_compile(cg,
417 sys::Path uniqueObjPath("/tmp/llvmgold.o");
418 if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) {
419 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
422 raw_fd_ostream *objFile =
423 new raw_fd_ostream(uniqueObjPath.c_str(), ErrMsg,
424 raw_fd_ostream::F_Binary);
425 if (!ErrMsg.empty()) {
427 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
431 objFile->write(buffer, bufsize);
434 lto_codegen_dispose(cg);
436 if ((*add_input_file)(const_cast<char*>(uniqueObjPath.c_str())) != LDPS_OK) {
437 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
438 (*message)(LDPL_ERROR, "File left behind in: %s", uniqueObjPath.c_str());
442 Cleanup.push_back(uniqueObjPath);
447 static ld_plugin_status cleanup_hook(void) {
450 for (int i = 0, e = Cleanup.size(); i != e; ++i)
451 if (Cleanup[i].eraseFromDisk(false, &ErrMsg))
452 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),