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 "plugin-api.h"
17 #include "llvm-c/lto.h"
19 #include "llvm/Support/raw_ostream.h"
20 #include "llvm/System/Path.h"
21 #include "llvm/System/Program.h"
33 ld_plugin_status discard_message(int level, const char *format, ...) {
34 // Die loudly. Recent versions of Gold pass ld_plugin_message as the first
35 // callback in the transfer vector. This should never be called.
39 ld_plugin_add_symbols add_symbols = NULL;
40 ld_plugin_get_symbols get_symbols = NULL;
41 ld_plugin_add_input_file add_input_file = NULL;
42 ld_plugin_message message = discard_message;
47 bool generate_api_file = false;
48 const char *as_path = NULL;
53 std::vector<ld_plugin_symbol> syms;
56 lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
57 std::list<claimed_file> Modules;
58 std::vector<sys::Path> Cleanup;
61 ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
63 ld_plugin_status all_symbols_read_hook(void);
64 ld_plugin_status cleanup_hook(void);
66 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
67 ld_plugin_status onload(ld_plugin_tv *tv) {
68 // We're given a pointer to the first transfer vector. We read through them
69 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
70 // contain pointers to functions that we need to call to register our own
71 // hooks. The others are addresses of functions we can use to call into gold
74 bool registeredClaimFile = false;
75 bool registeredAllSymbolsRead = false;
76 bool registeredCleanup = false;
78 for (; tv->tv_tag != LDPT_NULL; ++tv) {
80 case LDPT_API_VERSION:
81 api_version = tv->tv_u.tv_val;
83 case LDPT_GOLD_VERSION: // major * 100 + minor
84 gold_version = tv->tv_u.tv_val;
86 case LDPT_LINKER_OUTPUT:
87 switch (tv->tv_u.tv_val) {
90 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
92 case LDPO_EXEC: // .exe
93 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
96 (*message)(LDPL_ERROR, "Unknown output file type %d",
100 // TODO: add an option to disable PIC.
101 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
104 if (strcmp("generate-api-file", tv->tv_u.tv_string) == 0) {
105 generate_api_file = true;
106 } else if (strncmp("as=", tv->tv_u.tv_string, 3) == 0) {
108 (*message)(LDPL_WARNING, "Path to as specified twice. "
109 "Discarding %s", tv->tv_u.tv_string);
111 as_path = strdup(tv->tv_u.tv_string + 3);
114 (*message)(LDPL_WARNING, "Ignoring flag %s", tv->tv_u.tv_string);
117 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
118 ld_plugin_register_claim_file callback;
119 callback = tv->tv_u.tv_register_claim_file;
121 if ((*callback)(claim_file_hook) != LDPS_OK)
124 registeredClaimFile = true;
126 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
127 ld_plugin_register_all_symbols_read callback;
128 callback = tv->tv_u.tv_register_all_symbols_read;
130 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
133 registeredAllSymbolsRead = true;
135 case LDPT_REGISTER_CLEANUP_HOOK: {
136 ld_plugin_register_cleanup callback;
137 callback = tv->tv_u.tv_register_cleanup;
139 if ((*callback)(cleanup_hook) != LDPS_OK)
142 registeredCleanup = true;
144 case LDPT_ADD_SYMBOLS:
145 add_symbols = tv->tv_u.tv_add_symbols;
147 case LDPT_GET_SYMBOLS:
148 get_symbols = tv->tv_u.tv_get_symbols;
150 case LDPT_ADD_INPUT_FILE:
151 add_input_file = tv->tv_u.tv_add_input_file;
154 message = tv->tv_u.tv_message;
161 if (!registeredClaimFile) {
162 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
166 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
173 /// claim_file_hook - called by gold to see whether this file is one that
174 /// our plugin can handle. We'll try to open it and register all the symbols
175 /// with add_symbol if possible.
176 ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
180 // Gold has found what might be IR part-way inside of a file, such as
182 if (lseek(file->fd, file->offset, SEEK_SET) == -1) {
183 (*message)(LDPL_ERROR,
184 "Failed to seek to archive member of %s at offset %d: %s\n",
186 file->offset, strerror(errno));
189 buf = malloc(file->filesize);
191 (*message)(LDPL_ERROR,
192 "Failed to allocate buffer for archive member of size: %d\n",
196 if (read(file->fd, buf, file->filesize) != file->filesize) {
197 (*message)(LDPL_ERROR,
198 "Failed to read archive member of %s at offset %d: %s\n",
205 if (!lto_module_is_object_file_in_memory(buf, file->filesize)) {
209 } else if (!lto_module_is_object_file(file->name))
213 Modules.resize(Modules.size() + 1);
214 claimed_file &cf = Modules.back();
216 cf.M = buf ? lto_module_create_from_memory(buf, file->filesize) :
217 lto_module_create(file->name);
220 (*message)(LDPL_ERROR, "Failed to create LLVM module: %s",
221 lto_get_error_message());
224 cf.handle = file->handle;
225 unsigned sym_count = lto_module_get_num_symbols(cf.M);
226 cf.syms.reserve(sym_count);
228 for (unsigned i = 0; i != sym_count; ++i) {
229 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(cf.M, i);
230 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
233 cf.syms.push_back(ld_plugin_symbol());
234 ld_plugin_symbol &sym = cf.syms.back();
235 sym.name = const_cast<char *>(lto_module_get_symbol_name(cf.M, i));
238 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
240 case LTO_SYMBOL_SCOPE_HIDDEN:
241 sym.visibility = LDPV_HIDDEN;
243 case LTO_SYMBOL_SCOPE_PROTECTED:
244 sym.visibility = LDPV_PROTECTED;
247 case LTO_SYMBOL_SCOPE_DEFAULT:
248 sym.visibility = LDPV_DEFAULT;
251 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
255 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
256 switch (definition) {
257 case LTO_SYMBOL_DEFINITION_REGULAR:
260 case LTO_SYMBOL_DEFINITION_UNDEFINED:
261 sym.def = LDPK_UNDEF;
263 case LTO_SYMBOL_DEFINITION_TENTATIVE:
264 sym.def = LDPK_COMMON;
266 case LTO_SYMBOL_DEFINITION_WEAK:
267 sym.def = LDPK_WEAKDEF;
269 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
270 sym.def = LDPK_WEAKUNDEF;
273 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
277 // LLVM never emits COMDAT.
279 sym.comdat_key = NULL;
281 sym.resolution = LDPR_UNKNOWN;
284 cf.syms.reserve(cf.syms.size());
286 if (!cf.syms.empty()) {
287 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
288 (*message)(LDPL_ERROR, "Unable to add symbols!");
296 /// all_symbols_read_hook - gold informs us that all symbols have been read.
297 /// At this point, we use get_symbols to see if any of our definitions have
298 /// been overridden by a native object file. Then, perform optimization and
300 ld_plugin_status all_symbols_read_hook(void) {
301 lto_code_gen_t cg = lto_codegen_create();
303 for (std::list<claimed_file>::iterator I = Modules.begin(),
304 E = Modules.end(); I != E; ++I)
305 lto_codegen_add_module(cg, I->M);
307 std::ofstream api_file;
308 if (generate_api_file) {
309 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
310 if (!api_file.is_open()) {
311 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
316 // If we don't preserve any symbols, libLTO will assume that all symbols are
317 // needed. Keep all symbols unless we're producing a final executable.
318 if (output_type == LTO_CODEGEN_PIC_MODEL_STATIC) {
319 bool anySymbolsPreserved = false;
320 for (std::list<claimed_file>::iterator I = Modules.begin(),
321 E = Modules.end(); I != E; ++I) {
322 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
323 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
324 if (I->syms[i].resolution == LDPR_PREVAILING_DEF ||
325 (I->syms[i].def == LDPK_COMMON &&
326 I->syms[i].resolution == LDPR_RESOLVED_IR)) {
327 lto_codegen_add_must_preserve_symbol(cg, I->syms[i].name);
328 anySymbolsPreserved = true;
330 if (generate_api_file)
331 api_file << I->syms[i].name << "\n";
336 if (generate_api_file)
339 if (!anySymbolsPreserved) {
340 // This entire file is unnecessary!
341 lto_codegen_dispose(cg);
346 lto_codegen_set_pic_model(cg, output_type);
347 lto_codegen_set_debug_model(cg, LTO_DEBUG_MODEL_DWARF);
349 sys::Path p = sys::Program::FindProgramByName(as_path);
350 lto_codegen_set_assembler_path(cg, p.c_str());
354 const char *buffer = static_cast<const char *>(lto_codegen_compile(cg,
359 sys::Path uniqueObjPath("/tmp/llvmgold.o");
360 if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) {
361 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
364 raw_fd_ostream *objFile = new raw_fd_ostream(uniqueObjPath.c_str(), true,
366 if (!ErrMsg.empty()) {
368 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
372 objFile->write(buffer, bufsize);
375 lto_codegen_dispose(cg);
377 if ((*add_input_file)(const_cast<char*>(uniqueObjPath.c_str())) != LDPS_OK) {
378 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
379 (*message)(LDPL_ERROR, "File left behind in: %s", uniqueObjPath.c_str());
383 Cleanup.push_back(uniqueObjPath);
388 ld_plugin_status cleanup_hook(void) {
391 for (int i = 0, e = Cleanup.size(); i != e; ++i)
392 if (Cleanup[i].eraseFromDisk(false, &ErrMsg))
393 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),