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/Errno.h"
21 #include "llvm/System/Path.h"
22 #include "llvm/System/Program.h"
34 ld_plugin_status discard_message(int level, const char *format, ...) {
35 // Die loudly. Recent versions of Gold pass ld_plugin_message as the first
36 // callback in the transfer vector. This should never be called.
40 ld_plugin_add_symbols add_symbols = NULL;
41 ld_plugin_get_symbols get_symbols = NULL;
42 ld_plugin_add_input_file add_input_file = NULL;
43 ld_plugin_message message = discard_message;
48 bool generate_api_file = false;
49 const char *as_path = NULL;
54 std::vector<ld_plugin_symbol> syms;
57 lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
58 std::list<claimed_file> Modules;
59 std::vector<sys::Path> Cleanup;
62 ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
64 ld_plugin_status all_symbols_read_hook(void);
65 ld_plugin_status cleanup_hook(void);
67 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
68 ld_plugin_status onload(ld_plugin_tv *tv) {
69 // We're given a pointer to the first transfer vector. We read through them
70 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
71 // contain pointers to functions that we need to call to register our own
72 // hooks. The others are addresses of functions we can use to call into gold
75 bool registeredClaimFile = false;
76 bool registeredAllSymbolsRead = false;
77 bool registeredCleanup = false;
79 for (; tv->tv_tag != LDPT_NULL; ++tv) {
81 case LDPT_API_VERSION:
82 api_version = tv->tv_u.tv_val;
84 case LDPT_GOLD_VERSION: // major * 100 + minor
85 gold_version = tv->tv_u.tv_val;
87 case LDPT_LINKER_OUTPUT:
88 switch (tv->tv_u.tv_val) {
91 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
93 case LDPO_EXEC: // .exe
94 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
97 (*message)(LDPL_ERROR, "Unknown output file type %d",
101 // TODO: add an option to disable PIC.
102 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
105 if (strcmp("generate-api-file", tv->tv_u.tv_string) == 0) {
106 generate_api_file = true;
107 } else if (strncmp("as=", tv->tv_u.tv_string, 3) == 0) {
109 (*message)(LDPL_WARNING, "Path to as specified twice. "
110 "Discarding %s", tv->tv_u.tv_string);
112 as_path = strdup(tv->tv_u.tv_string + 3);
115 (*message)(LDPL_WARNING, "Ignoring flag %s", tv->tv_u.tv_string);
118 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
119 ld_plugin_register_claim_file callback;
120 callback = tv->tv_u.tv_register_claim_file;
122 if ((*callback)(claim_file_hook) != LDPS_OK)
125 registeredClaimFile = true;
127 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
128 ld_plugin_register_all_symbols_read callback;
129 callback = tv->tv_u.tv_register_all_symbols_read;
131 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
134 registeredAllSymbolsRead = true;
136 case LDPT_REGISTER_CLEANUP_HOOK: {
137 ld_plugin_register_cleanup callback;
138 callback = tv->tv_u.tv_register_cleanup;
140 if ((*callback)(cleanup_hook) != LDPS_OK)
143 registeredCleanup = true;
145 case LDPT_ADD_SYMBOLS:
146 add_symbols = tv->tv_u.tv_add_symbols;
148 case LDPT_GET_SYMBOLS:
149 get_symbols = tv->tv_u.tv_get_symbols;
151 case LDPT_ADD_INPUT_FILE:
152 add_input_file = tv->tv_u.tv_add_input_file;
155 message = tv->tv_u.tv_message;
162 if (!registeredClaimFile) {
163 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
167 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
174 /// claim_file_hook - called by gold to see whether this file is one that
175 /// our plugin can handle. We'll try to open it and register all the symbols
176 /// with add_symbol if possible.
177 ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
181 // Gold has found what might be IR part-way inside of a file, such as
183 if (lseek(file->fd, file->offset, SEEK_SET) == -1) {
184 (*message)(LDPL_ERROR,
185 "Failed to seek to archive member of %s at offset %d: %s\n",
187 file->offset, sys::StrError(errno).c_str());
190 buf = malloc(file->filesize);
192 (*message)(LDPL_ERROR,
193 "Failed to allocate buffer for archive member of size: %d\n",
197 if (read(file->fd, buf, file->filesize) != file->filesize) {
198 (*message)(LDPL_ERROR,
199 "Failed to read archive member of %s at offset %d: %s\n",
202 sys::StrError(errno).c_str());
206 if (!lto_module_is_object_file_in_memory(buf, file->filesize)) {
210 } else if (!lto_module_is_object_file(file->name))
214 Modules.resize(Modules.size() + 1);
215 claimed_file &cf = Modules.back();
217 cf.M = buf ? lto_module_create_from_memory(buf, file->filesize) :
218 lto_module_create(file->name);
221 (*message)(LDPL_ERROR, "Failed to create LLVM module: %s",
222 lto_get_error_message());
225 cf.handle = file->handle;
226 unsigned sym_count = lto_module_get_num_symbols(cf.M);
227 cf.syms.reserve(sym_count);
229 for (unsigned i = 0; i != sym_count; ++i) {
230 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(cf.M, i);
231 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
234 cf.syms.push_back(ld_plugin_symbol());
235 ld_plugin_symbol &sym = cf.syms.back();
236 sym.name = const_cast<char *>(lto_module_get_symbol_name(cf.M, i));
239 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
241 case LTO_SYMBOL_SCOPE_HIDDEN:
242 sym.visibility = LDPV_HIDDEN;
244 case LTO_SYMBOL_SCOPE_PROTECTED:
245 sym.visibility = LDPV_PROTECTED;
248 case LTO_SYMBOL_SCOPE_DEFAULT:
249 sym.visibility = LDPV_DEFAULT;
252 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
256 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
257 switch (definition) {
258 case LTO_SYMBOL_DEFINITION_REGULAR:
261 case LTO_SYMBOL_DEFINITION_UNDEFINED:
262 sym.def = LDPK_UNDEF;
264 case LTO_SYMBOL_DEFINITION_TENTATIVE:
265 sym.def = LDPK_COMMON;
267 case LTO_SYMBOL_DEFINITION_WEAK:
268 sym.def = LDPK_WEAKDEF;
270 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
271 sym.def = LDPK_WEAKUNDEF;
274 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
278 // LLVM never emits COMDAT.
280 sym.comdat_key = NULL;
282 sym.resolution = LDPR_UNKNOWN;
285 cf.syms.reserve(cf.syms.size());
287 if (!cf.syms.empty()) {
288 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
289 (*message)(LDPL_ERROR, "Unable to add symbols!");
297 /// all_symbols_read_hook - gold informs us that all symbols have been read.
298 /// At this point, we use get_symbols to see if any of our definitions have
299 /// been overridden by a native object file. Then, perform optimization and
301 ld_plugin_status all_symbols_read_hook(void) {
302 lto_code_gen_t cg = lto_codegen_create();
304 for (std::list<claimed_file>::iterator I = Modules.begin(),
305 E = Modules.end(); I != E; ++I)
306 lto_codegen_add_module(cg, I->M);
308 std::ofstream api_file;
309 if (generate_api_file) {
310 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
311 if (!api_file.is_open()) {
312 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
317 // If we don't preserve any symbols, libLTO will assume that all symbols are
318 // needed. Keep all symbols unless we're producing a final executable.
319 if (output_type == LTO_CODEGEN_PIC_MODEL_STATIC) {
320 bool anySymbolsPreserved = false;
321 for (std::list<claimed_file>::iterator I = Modules.begin(),
322 E = Modules.end(); I != E; ++I) {
323 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
324 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
325 if (I->syms[i].resolution == LDPR_PREVAILING_DEF ||
326 (I->syms[i].def == LDPK_COMMON &&
327 I->syms[i].resolution == LDPR_RESOLVED_IR)) {
328 lto_codegen_add_must_preserve_symbol(cg, I->syms[i].name);
329 anySymbolsPreserved = true;
331 if (generate_api_file)
332 api_file << I->syms[i].name << "\n";
337 if (generate_api_file)
340 if (!anySymbolsPreserved) {
341 // This entire file is unnecessary!
342 lto_codegen_dispose(cg);
347 lto_codegen_set_pic_model(cg, output_type);
348 lto_codegen_set_debug_model(cg, LTO_DEBUG_MODEL_DWARF);
350 sys::Path p = sys::Program::FindProgramByName(as_path);
351 lto_codegen_set_assembler_path(cg, p.c_str());
355 const char *buffer = static_cast<const char *>(lto_codegen_compile(cg,
360 sys::Path uniqueObjPath("/tmp/llvmgold.o");
361 if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) {
362 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
365 raw_fd_ostream *objFile =
366 new raw_fd_ostream(uniqueObjPath.c_str(), ErrMsg,
367 raw_fd_ostream::F_Binary);
368 if (!ErrMsg.empty()) {
370 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
374 objFile->write(buffer, bufsize);
377 lto_codegen_dispose(cg);
379 if ((*add_input_file)(const_cast<char*>(uniqueObjPath.c_str())) != LDPS_OK) {
380 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
381 (*message)(LDPL_ERROR, "File left behind in: %s", uniqueObjPath.c_str());
385 Cleanup.push_back(uniqueObjPath);
390 ld_plugin_status cleanup_hook(void) {
393 for (int i = 0, e = Cleanup.size(); i != e; ++i)
394 if (Cleanup[i].eraseFromDisk(false, &ErrMsg))
395 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),