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 const char *as_path = NULL;
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)
79 if (strcmp("generate-api-file", opt) == 0) {
80 generate_api_file = true;
81 } else if (strncmp("as=", opt, 3) == 0) {
83 (*message)(LDPL_WARNING, "Path to as specified twice. "
84 "Discarding %s", opt);
86 as_path = strdup(opt + 3);
88 } else if (strcmp("emit-llvm", opt) == 0) {
89 generate_bc_file = BC_ONLY;
90 } else if (strcmp("also-emit-llvm", opt) == 0) {
91 generate_bc_file = BC_ALSO;
92 } else if (llvm::StringRef(opt).startswith("also-emit-llvm=")) {
93 const char *path = opt + strlen("also-emit-llvm=");
94 generate_bc_file = BC_ALSO;
95 if (!bc_path.empty()) {
96 (*message)(LDPL_WARNING, "Path to the output IL file specified twice. "
97 "Discarding %s", opt);
102 // Save this option to pass to the code generator.
103 extra.push_back(std::string(opt));
108 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
110 static ld_plugin_status all_symbols_read_hook(void);
111 static ld_plugin_status cleanup_hook(void);
113 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
114 ld_plugin_status onload(ld_plugin_tv *tv) {
115 // We're given a pointer to the first transfer vector. We read through them
116 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
117 // contain pointers to functions that we need to call to register our own
118 // hooks. The others are addresses of functions we can use to call into gold
121 bool registeredClaimFile = false;
122 bool registeredAllSymbolsRead = false;
123 bool registeredCleanup = false;
125 for (; tv->tv_tag != LDPT_NULL; ++tv) {
126 switch (tv->tv_tag) {
127 case LDPT_API_VERSION:
128 api_version = tv->tv_u.tv_val;
130 case LDPT_GOLD_VERSION: // major * 100 + minor
131 gold_version = tv->tv_u.tv_val;
133 case LDPT_OUTPUT_NAME:
134 output_name = tv->tv_u.tv_string;
136 case LDPT_LINKER_OUTPUT:
137 switch (tv->tv_u.tv_val) {
139 case LDPO_DYN: // .so
140 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
142 case LDPO_EXEC: // .exe
143 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
146 (*message)(LDPL_ERROR, "Unknown output file type %d",
150 // TODO: add an option to disable PIC.
151 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
154 options::process_plugin_option(tv->tv_u.tv_string);
156 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
157 ld_plugin_register_claim_file callback;
158 callback = tv->tv_u.tv_register_claim_file;
160 if ((*callback)(claim_file_hook) != LDPS_OK)
163 registeredClaimFile = true;
165 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
166 ld_plugin_register_all_symbols_read callback;
167 callback = tv->tv_u.tv_register_all_symbols_read;
169 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
172 registeredAllSymbolsRead = true;
174 case LDPT_REGISTER_CLEANUP_HOOK: {
175 ld_plugin_register_cleanup callback;
176 callback = tv->tv_u.tv_register_cleanup;
178 if ((*callback)(cleanup_hook) != LDPS_OK)
181 registeredCleanup = true;
183 case LDPT_ADD_SYMBOLS:
184 add_symbols = tv->tv_u.tv_add_symbols;
186 case LDPT_GET_SYMBOLS:
187 get_symbols = tv->tv_u.tv_get_symbols;
189 case LDPT_ADD_INPUT_FILE:
190 add_input_file = tv->tv_u.tv_add_input_file;
193 message = tv->tv_u.tv_message;
200 if (!registeredClaimFile) {
201 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
205 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
212 /// claim_file_hook - called by gold to see whether this file is one that
213 /// our plugin can handle. We'll try to open it and register all the symbols
214 /// with add_symbol if possible.
215 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
219 // Gold has found what might be IR part-way inside of a file, such as
221 if (lseek(file->fd, file->offset, SEEK_SET) == -1) {
222 (*message)(LDPL_ERROR,
223 "Failed to seek to archive member of %s at offset %d: %s\n",
225 file->offset, sys::StrError(errno).c_str());
228 buf = malloc(file->filesize);
230 (*message)(LDPL_ERROR,
231 "Failed to allocate buffer for archive member of size: %d\n",
235 if (read(file->fd, buf, file->filesize) != file->filesize) {
236 (*message)(LDPL_ERROR,
237 "Failed to read archive member of %s at offset %d: %s\n",
240 sys::StrError(errno).c_str());
244 if (!lto_module_is_object_file_in_memory(buf, file->filesize)) {
248 } else if (!lto_module_is_object_file(file->name))
252 Modules.resize(Modules.size() + 1);
253 claimed_file &cf = Modules.back();
255 cf.M = buf ? lto_module_create_from_memory(buf, file->filesize) :
256 lto_module_create(file->name);
259 (*message)(LDPL_ERROR, "Failed to create LLVM module: %s",
260 lto_get_error_message());
263 cf.handle = file->handle;
264 unsigned sym_count = lto_module_get_num_symbols(cf.M);
265 cf.syms.reserve(sym_count);
267 for (unsigned i = 0; i != sym_count; ++i) {
268 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(cf.M, i);
269 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
272 cf.syms.push_back(ld_plugin_symbol());
273 ld_plugin_symbol &sym = cf.syms.back();
274 sym.name = const_cast<char *>(lto_module_get_symbol_name(cf.M, i));
277 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
279 case LTO_SYMBOL_SCOPE_HIDDEN:
280 sym.visibility = LDPV_HIDDEN;
282 case LTO_SYMBOL_SCOPE_PROTECTED:
283 sym.visibility = LDPV_PROTECTED;
286 case LTO_SYMBOL_SCOPE_DEFAULT:
287 sym.visibility = LDPV_DEFAULT;
290 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
294 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
295 switch (definition) {
296 case LTO_SYMBOL_DEFINITION_REGULAR:
299 case LTO_SYMBOL_DEFINITION_UNDEFINED:
300 sym.def = LDPK_UNDEF;
302 case LTO_SYMBOL_DEFINITION_TENTATIVE:
303 sym.def = LDPK_COMMON;
305 case LTO_SYMBOL_DEFINITION_WEAK:
306 sym.def = LDPK_WEAKDEF;
308 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
309 sym.def = LDPK_WEAKUNDEF;
312 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
316 // LLVM never emits COMDAT.
318 sym.comdat_key = NULL;
320 sym.resolution = LDPR_UNKNOWN;
323 cf.syms.reserve(cf.syms.size());
325 if (!cf.syms.empty()) {
326 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
327 (*message)(LDPL_ERROR, "Unable to add symbols!");
335 /// all_symbols_read_hook - gold informs us that all symbols have been read.
336 /// At this point, we use get_symbols to see if any of our definitions have
337 /// been overridden by a native object file. Then, perform optimization and
339 static ld_plugin_status all_symbols_read_hook(void) {
340 lto_code_gen_t cg = lto_codegen_create();
342 for (std::list<claimed_file>::iterator I = Modules.begin(),
343 E = Modules.end(); I != E; ++I)
344 lto_codegen_add_module(cg, I->M);
346 std::ofstream api_file;
347 if (options::generate_api_file) {
348 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
349 if (!api_file.is_open()) {
350 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
355 // If we don't preserve any symbols, libLTO will assume that all symbols are
356 // needed. Keep all symbols unless we're producing a final executable.
357 bool anySymbolsPreserved = false;
358 for (std::list<claimed_file>::iterator I = Modules.begin(),
359 E = Modules.end(); I != E; ++I) {
360 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
361 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
362 if (I->syms[i].resolution == LDPR_PREVAILING_DEF) {
363 lto_codegen_add_must_preserve_symbol(cg, I->syms[i].name);
364 anySymbolsPreserved = true;
366 if (options::generate_api_file)
367 api_file << I->syms[i].name << "\n";
371 if (options::generate_api_file)
374 if (!anySymbolsPreserved) {
375 // This entire file is unnecessary!
376 lto_codegen_dispose(cg);
381 lto_codegen_set_pic_model(cg, output_type);
382 lto_codegen_set_debug_model(cg, LTO_DEBUG_MODEL_DWARF);
383 if (options::as_path) {
384 sys::Path p = sys::Program::FindProgramByName(options::as_path);
385 lto_codegen_set_assembler_path(cg, p.c_str());
387 // Pass through extra options to the code generator.
388 if (!options::extra.empty()) {
389 for (std::vector<std::string>::iterator it = options::extra.begin();
390 it != options::extra.end(); ++it) {
391 lto_codegen_debug_options(cg, (*it).c_str());
396 if (options::generate_bc_file != options::BC_NO) {
398 if (options::generate_bc_file == options::BC_ONLY)
400 else if (!options::bc_path.empty())
401 path = options::bc_path;
403 path = output_name + ".bc";
404 bool err = lto_codegen_write_merged_modules(cg, path.c_str());
406 (*message)(LDPL_FATAL, "Failed to write the output file.");
407 if (options::generate_bc_file == options::BC_ONLY)
411 const char *buffer = static_cast<const char *>(lto_codegen_compile(cg,
416 sys::Path uniqueObjPath("/tmp/llvmgold.o");
417 if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) {
418 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
421 raw_fd_ostream *objFile =
422 new raw_fd_ostream(uniqueObjPath.c_str(), ErrMsg,
423 raw_fd_ostream::F_Binary);
424 if (!ErrMsg.empty()) {
426 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
430 objFile->write(buffer, bufsize);
433 lto_codegen_dispose(cg);
435 if ((*add_input_file)(const_cast<char*>(uniqueObjPath.c_str())) != LDPS_OK) {
436 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
437 (*message)(LDPL_ERROR, "File left behind in: %s", uniqueObjPath.c_str());
441 Cleanup.push_back(uniqueObjPath);
446 static ld_plugin_status cleanup_hook(void) {
449 for (int i = 0, e = Cleanup.size(); i != e; ++i)
450 if (Cleanup[i].eraseFromDisk(false, &ErrMsg))
451 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),