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"
32 ld_plugin_status discard_message(int level, const char *format, ...) {
33 // Die loudly. Recent versions of Gold pass ld_plugin_message as the first
34 // callback in the transfer vector. This should never be called.
38 ld_plugin_add_symbols add_symbols = NULL;
39 ld_plugin_get_symbols get_symbols = NULL;
40 ld_plugin_add_input_file add_input_file = NULL;
41 ld_plugin_message message = discard_message;
46 bool generate_api_file = false;
47 const char *gcc_path = NULL;
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("gcc=", tv->tv_u.tv_string, 4) == 0) {
108 (*message)(LDPL_WARNING, "Path to gcc specified twice. "
109 "Discarding %s", tv->tv_u.tv_string);
111 gcc_path = strdup(tv->tv_u.tv_string + 4);
113 } else if (strncmp("as=", tv->tv_u.tv_string, 3) == 0) {
115 (*message)(LDPL_WARNING, "Path to as specified twice. "
116 "Discarding %s", tv->tv_u.tv_string);
118 as_path = strdup(tv->tv_u.tv_string + 3);
121 (*message)(LDPL_WARNING, "Ignoring flag %s", tv->tv_u.tv_string);
124 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
125 ld_plugin_register_claim_file callback;
126 callback = tv->tv_u.tv_register_claim_file;
128 if ((*callback)(claim_file_hook) != LDPS_OK)
131 registeredClaimFile = true;
133 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
134 ld_plugin_register_all_symbols_read callback;
135 callback = tv->tv_u.tv_register_all_symbols_read;
137 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
140 registeredAllSymbolsRead = true;
142 case LDPT_REGISTER_CLEANUP_HOOK: {
143 ld_plugin_register_cleanup callback;
144 callback = tv->tv_u.tv_register_cleanup;
146 if ((*callback)(cleanup_hook) != LDPS_OK)
149 registeredCleanup = true;
151 case LDPT_ADD_SYMBOLS:
152 add_symbols = tv->tv_u.tv_add_symbols;
154 case LDPT_GET_SYMBOLS:
155 get_symbols = tv->tv_u.tv_get_symbols;
157 case LDPT_ADD_INPUT_FILE:
158 add_input_file = tv->tv_u.tv_add_input_file;
161 message = tv->tv_u.tv_message;
168 if (!registeredClaimFile) {
169 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
173 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
180 /// claim_file_hook - called by gold to see whether this file is one that
181 /// our plugin can handle. We'll try to open it and register all the symbols
182 /// with add_symbol if possible.
183 ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
187 // Gold has found what might be IR part-way inside of a file, such as
189 if (lseek(file->fd, file->offset, SEEK_SET) == -1) {
190 (*message)(LDPL_ERROR,
191 "Failed to seek to archive member of %s at offset %d: %s\n",
193 file->offset, strerror(errno));
196 buf = malloc(file->filesize);
198 (*message)(LDPL_ERROR,
199 "Failed to allocate buffer for archive member of size: %d\n",
203 if (read(file->fd, buf, file->filesize) != file->filesize) {
204 (*message)(LDPL_ERROR,
205 "Failed to read archive member of %s at offset %d: %s\n",
212 if (!lto_module_is_object_file_in_memory(buf, file->filesize)) {
216 } else if (!lto_module_is_object_file(file->name))
220 Modules.resize(Modules.size() + 1);
221 claimed_file &cf = Modules.back();
223 cf.M = buf ? lto_module_create_from_memory(buf, file->filesize) :
224 lto_module_create(file->name);
227 (*message)(LDPL_ERROR, "Failed to create LLVM module: %s",
228 lto_get_error_message());
231 cf.handle = file->handle;
232 unsigned sym_count = lto_module_get_num_symbols(cf.M);
233 cf.syms.reserve(sym_count);
235 for (unsigned i = 0; i != sym_count; ++i) {
236 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(cf.M, i);
237 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
240 cf.syms.push_back(ld_plugin_symbol());
241 ld_plugin_symbol &sym = cf.syms.back();
242 sym.name = const_cast<char *>(lto_module_get_symbol_name(cf.M, i));
245 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
247 case LTO_SYMBOL_SCOPE_HIDDEN:
248 sym.visibility = LDPV_HIDDEN;
250 case LTO_SYMBOL_SCOPE_PROTECTED:
251 sym.visibility = LDPV_PROTECTED;
254 case LTO_SYMBOL_SCOPE_DEFAULT:
255 sym.visibility = LDPV_DEFAULT;
258 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
262 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
263 switch (definition) {
264 case LTO_SYMBOL_DEFINITION_REGULAR:
267 case LTO_SYMBOL_DEFINITION_UNDEFINED:
268 sym.def = LDPK_UNDEF;
270 case LTO_SYMBOL_DEFINITION_TENTATIVE:
271 sym.def = LDPK_COMMON;
273 case LTO_SYMBOL_DEFINITION_WEAK:
274 sym.def = LDPK_WEAKDEF;
276 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
277 sym.def = LDPK_WEAKUNDEF;
280 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
284 // LLVM never emits COMDAT.
286 sym.comdat_key = NULL;
288 sym.resolution = LDPR_UNKNOWN;
291 cf.syms.reserve(cf.syms.size());
293 if (!cf.syms.empty()) {
294 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
295 (*message)(LDPL_ERROR, "Unable to add symbols!");
303 /// all_symbols_read_hook - gold informs us that all symbols have been read.
304 /// At this point, we use get_symbols to see if any of our definitions have
305 /// been overridden by a native object file. Then, perform optimization and
307 ld_plugin_status all_symbols_read_hook(void) {
308 lto_code_gen_t cg = lto_codegen_create();
310 for (std::list<claimed_file>::iterator I = Modules.begin(),
311 E = Modules.end(); I != E; ++I)
312 lto_codegen_add_module(cg, I->M);
314 std::ofstream api_file;
315 if (generate_api_file) {
316 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
317 if (!api_file.is_open()) {
318 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
323 // If we don't preserve any symbols, libLTO will assume that all symbols are
324 // needed. Keep all symbols unless we're producing a final executable.
325 if (output_type == LTO_CODEGEN_PIC_MODEL_STATIC) {
326 bool anySymbolsPreserved = false;
327 for (std::list<claimed_file>::iterator I = Modules.begin(),
328 E = Modules.end(); I != E; ++I) {
329 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
330 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
331 if (I->syms[i].resolution == LDPR_PREVAILING_DEF ||
332 (I->syms[i].def == LDPK_COMMON &&
333 I->syms[i].resolution == LDPR_RESOLVED_IR)) {
334 lto_codegen_add_must_preserve_symbol(cg, I->syms[i].name);
335 anySymbolsPreserved = true;
337 if (generate_api_file)
338 api_file << I->syms[i].name << "\n";
343 if (generate_api_file)
346 if (!anySymbolsPreserved) {
347 // This entire file is unnecessary!
348 lto_codegen_dispose(cg);
353 lto_codegen_set_pic_model(cg, output_type);
354 lto_codegen_set_debug_model(cg, LTO_DEBUG_MODEL_DWARF);
356 lto_codegen_set_gcc_path(cg, gcc_path);
358 lto_codegen_set_assembler_path(cg, as_path);
361 const char *buffer = static_cast<const char *>(lto_codegen_compile(cg,
366 sys::Path uniqueObjPath("/tmp/llvmgold.o");
367 if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) {
368 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
371 raw_fd_ostream *objFile = new raw_fd_ostream(uniqueObjPath.c_str(), true,
373 if (!ErrMsg.empty()) {
375 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
379 objFile->write(buffer, bufsize);
382 lto_codegen_dispose(cg);
384 if ((*add_input_file)(const_cast<char*>(uniqueObjPath.c_str())) != LDPS_OK) {
385 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
386 (*message)(LDPL_ERROR, "File left behind in: %s", uniqueObjPath.c_str());
390 Cleanup.push_back(uniqueObjPath);
395 ld_plugin_status cleanup_hook(void) {
398 for (int i = 0, e = Cleanup.size(); i != e; ++i)
399 if (Cleanup[i].eraseFromDisk(false, &ErrMsg))
400 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),