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_message message = discard_message;
53 std::vector<ld_plugin_symbol> syms;
56 lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
57 std::string output_name = "";
58 std::list<claimed_file> Modules;
59 std::vector<sys::Path> Cleanup;
63 enum generate_bc { BC_NO, BC_ALSO, BC_ONLY };
64 static bool generate_api_file = false;
65 static generate_bc generate_bc_file = BC_NO;
66 static std::string bc_path;
67 static std::string as_path;
68 static std::vector<std::string> pass_through;
69 // Additional options to pass into the code generator.
70 // Note: This array will contain all plugin options which are not claimed
71 // as plugin exclusive to pass to the code generator.
72 // For example, "generate-api-file" and "as"options are for the plugin
73 // use only and will not be passed.
74 static std::vector<std::string> extra;
76 static void process_plugin_option(const char* opt_)
80 llvm::StringRef opt = opt_;
82 if (opt == "generate-api-file") {
83 generate_api_file = true;
84 } else if (opt.startswith("as=")) {
85 if (!as_path.empty()) {
86 (*message)(LDPL_WARNING, "Path to as specified twice. "
87 "Discarding %s", opt_);
89 as_path = opt.substr(strlen("as="));
91 } else if (opt.startswith("pass-through=")) {
92 llvm::StringRef item = opt.substr(strlen("pass-through="));
93 pass_through.push_back(item.str());
94 } else if (opt == "emit-llvm") {
95 generate_bc_file = BC_ONLY;
96 } else if (opt == "also-emit-llvm") {
97 generate_bc_file = BC_ALSO;
98 } else if (opt.startswith("also-emit-llvm=")) {
99 llvm::StringRef path = opt.substr(strlen("also-emit-llvm="));
100 generate_bc_file = BC_ALSO;
101 if (!bc_path.empty()) {
102 (*message)(LDPL_WARNING, "Path to the output IL file specified twice. "
103 "Discarding %s", opt_);
108 // Save this option to pass to the code generator.
109 extra.push_back(opt);
114 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
116 static ld_plugin_status all_symbols_read_hook(void);
117 static ld_plugin_status cleanup_hook(void);
119 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
120 ld_plugin_status onload(ld_plugin_tv *tv) {
121 // We're given a pointer to the first transfer vector. We read through them
122 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
123 // contain pointers to functions that we need to call to register our own
124 // hooks. The others are addresses of functions we can use to call into gold
127 bool registeredClaimFile = false;
128 bool registeredAllSymbolsRead = false;
129 bool registeredCleanup = false;
131 for (; tv->tv_tag != LDPT_NULL; ++tv) {
132 switch (tv->tv_tag) {
133 case LDPT_API_VERSION:
134 api_version = tv->tv_u.tv_val;
136 case LDPT_GOLD_VERSION: // major * 100 + minor
137 gold_version = tv->tv_u.tv_val;
139 case LDPT_OUTPUT_NAME:
140 output_name = tv->tv_u.tv_string;
142 case LDPT_LINKER_OUTPUT:
143 switch (tv->tv_u.tv_val) {
145 case LDPO_DYN: // .so
146 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
148 case LDPO_EXEC: // .exe
149 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
152 (*message)(LDPL_ERROR, "Unknown output file type %d",
156 // TODO: add an option to disable PIC.
157 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
160 options::process_plugin_option(tv->tv_u.tv_string);
162 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
163 ld_plugin_register_claim_file callback;
164 callback = tv->tv_u.tv_register_claim_file;
166 if ((*callback)(claim_file_hook) != LDPS_OK)
169 registeredClaimFile = true;
171 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
172 ld_plugin_register_all_symbols_read callback;
173 callback = tv->tv_u.tv_register_all_symbols_read;
175 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
178 registeredAllSymbolsRead = true;
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 registeredCleanup = true;
189 case LDPT_ADD_SYMBOLS:
190 add_symbols = tv->tv_u.tv_add_symbols;
192 case LDPT_GET_SYMBOLS:
193 get_symbols = tv->tv_u.tv_get_symbols;
195 case LDPT_ADD_INPUT_FILE:
196 add_input_file = tv->tv_u.tv_add_input_file;
198 case LDPT_ADD_INPUT_LIBRARY:
199 add_input_library = tv->tv_u.tv_add_input_file;
202 message = tv->tv_u.tv_message;
209 if (!registeredClaimFile) {
210 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
214 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
221 /// claim_file_hook - called by gold to see whether this file is one that
222 /// our plugin can handle. We'll try to open it and register all the symbols
223 /// with add_symbol if possible.
224 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
228 // Gold has found what might be IR part-way inside of a file, such as
230 if (lseek(file->fd, file->offset, SEEK_SET) == -1) {
231 (*message)(LDPL_ERROR,
232 "Failed to seek to archive member of %s at offset %d: %s\n",
234 file->offset, sys::StrError(errno).c_str());
237 buf = malloc(file->filesize);
239 (*message)(LDPL_ERROR,
240 "Failed to allocate buffer for archive member of size: %d\n",
244 if (read(file->fd, buf, file->filesize) != file->filesize) {
245 (*message)(LDPL_ERROR,
246 "Failed to read archive member of %s at offset %d: %s\n",
249 sys::StrError(errno).c_str());
253 if (!lto_module_is_object_file_in_memory(buf, file->filesize)) {
257 } else if (!lto_module_is_object_file(file->name))
261 Modules.resize(Modules.size() + 1);
262 claimed_file &cf = Modules.back();
264 cf.M = buf ? lto_module_create_from_memory(buf, file->filesize) :
265 lto_module_create(file->name);
268 (*message)(LDPL_ERROR, "Failed to create LLVM module: %s",
269 lto_get_error_message());
272 cf.handle = file->handle;
273 unsigned sym_count = lto_module_get_num_symbols(cf.M);
274 cf.syms.reserve(sym_count);
276 for (unsigned i = 0; i != sym_count; ++i) {
277 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(cf.M, i);
278 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
281 cf.syms.push_back(ld_plugin_symbol());
282 ld_plugin_symbol &sym = cf.syms.back();
283 sym.name = const_cast<char *>(lto_module_get_symbol_name(cf.M, i));
286 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
288 case LTO_SYMBOL_SCOPE_HIDDEN:
289 sym.visibility = LDPV_HIDDEN;
291 case LTO_SYMBOL_SCOPE_PROTECTED:
292 sym.visibility = LDPV_PROTECTED;
295 case LTO_SYMBOL_SCOPE_DEFAULT:
296 sym.visibility = LDPV_DEFAULT;
299 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
303 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
304 switch (definition) {
305 case LTO_SYMBOL_DEFINITION_REGULAR:
308 case LTO_SYMBOL_DEFINITION_UNDEFINED:
309 sym.def = LDPK_UNDEF;
311 case LTO_SYMBOL_DEFINITION_TENTATIVE:
312 sym.def = LDPK_COMMON;
314 case LTO_SYMBOL_DEFINITION_WEAK:
315 sym.def = LDPK_WEAKDEF;
317 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
318 sym.def = LDPK_WEAKUNDEF;
321 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
325 // LLVM never emits COMDAT.
327 sym.comdat_key = NULL;
329 sym.resolution = LDPR_UNKNOWN;
332 cf.syms.reserve(cf.syms.size());
334 if (!cf.syms.empty()) {
335 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
336 (*message)(LDPL_ERROR, "Unable to add symbols!");
344 /// all_symbols_read_hook - gold informs us that all symbols have been read.
345 /// At this point, we use get_symbols to see if any of our definitions have
346 /// been overridden by a native object file. Then, perform optimization and
348 static ld_plugin_status all_symbols_read_hook(void) {
349 lto_code_gen_t cg = lto_codegen_create();
351 for (std::list<claimed_file>::iterator I = Modules.begin(),
352 E = Modules.end(); I != E; ++I)
353 lto_codegen_add_module(cg, I->M);
355 std::ofstream api_file;
356 if (options::generate_api_file) {
357 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
358 if (!api_file.is_open()) {
359 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
364 // If we don't preserve any symbols, libLTO will assume that all symbols are
365 // needed. Keep all symbols unless we're producing a final executable.
366 bool anySymbolsPreserved = false;
367 for (std::list<claimed_file>::iterator I = Modules.begin(),
368 E = Modules.end(); I != E; ++I) {
369 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
370 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
371 if (I->syms[i].resolution == LDPR_PREVAILING_DEF) {
372 lto_codegen_add_must_preserve_symbol(cg, I->syms[i].name);
373 anySymbolsPreserved = true;
375 if (options::generate_api_file)
376 api_file << I->syms[i].name << "\n";
381 if (options::generate_api_file)
384 if (!anySymbolsPreserved) {
385 // All of the IL is unnecessary!
386 lto_codegen_dispose(cg);
390 lto_codegen_set_pic_model(cg, output_type);
391 lto_codegen_set_debug_model(cg, LTO_DEBUG_MODEL_DWARF);
392 if (!options::as_path.empty()) {
393 sys::Path p = sys::Program::FindProgramByName(options::as_path);
394 lto_codegen_set_assembler_path(cg, p.c_str());
396 // Pass through extra options to the code generator.
397 if (!options::extra.empty()) {
398 for (std::vector<std::string>::iterator it = options::extra.begin();
399 it != options::extra.end(); ++it) {
400 lto_codegen_debug_options(cg, (*it).c_str());
405 if (options::generate_bc_file != options::BC_NO) {
407 if (options::generate_bc_file == options::BC_ONLY)
409 else if (!options::bc_path.empty())
410 path = options::bc_path;
412 path = output_name + ".bc";
413 bool err = lto_codegen_write_merged_modules(cg, path.c_str());
415 (*message)(LDPL_FATAL, "Failed to write the output file.");
416 if (options::generate_bc_file == options::BC_ONLY)
420 const char *buffer = static_cast<const char *>(lto_codegen_compile(cg,
425 sys::Path uniqueObjPath("/tmp/llvmgold.o");
426 if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) {
427 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
430 raw_fd_ostream objFile(uniqueObjPath.c_str(), ErrMsg,
431 raw_fd_ostream::F_Binary);
432 if (!ErrMsg.empty()) {
433 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
437 objFile.write(buffer, bufsize);
440 lto_codegen_dispose(cg);
442 if ((*add_input_file)(uniqueObjPath.c_str()) != LDPS_OK) {
443 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
444 (*message)(LDPL_ERROR, "File left behind in: %s", uniqueObjPath.c_str());
448 for (std::vector<std::string>::iterator i = options::pass_through.begin(),
449 e = options::pass_through.end();
451 std::string &item = *i;
452 const char *item_p = item.c_str();
453 if (llvm::StringRef(item).startswith("-l")) {
454 if (add_input_library(item_p + 2) != LDPS_OK) {
455 (*message)(LDPL_ERROR, "Unable to add library to the link.");
459 if (add_input_file(item_p) != LDPS_OK) {
460 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
466 Cleanup.push_back(uniqueObjPath);
471 static ld_plugin_status cleanup_hook(void) {
474 for (int i = 0, e = Cleanup.size(); i != e; ++i)
475 if (Cleanup[i].eraseFromDisk(false, &ErrMsg))
476 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),