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;
51 std::vector<ld_plugin_symbol> syms;
54 lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
55 std::list<claimed_file> Modules;
56 std::vector<sys::Path> Cleanup;
59 ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
61 ld_plugin_status all_symbols_read_hook(void);
62 ld_plugin_status cleanup_hook(void);
64 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
65 ld_plugin_status onload(ld_plugin_tv *tv) {
66 // We're given a pointer to the first transfer vector. We read through them
67 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
68 // contain pointers to functions that we need to call to register our own
69 // hooks. The others are addresses of functions we can use to call into gold
72 bool registeredClaimFile = false;
73 bool registeredAllSymbolsRead = false;
74 bool registeredCleanup = false;
76 for (; tv->tv_tag != LDPT_NULL; ++tv) {
78 case LDPT_API_VERSION:
79 api_version = tv->tv_u.tv_val;
81 case LDPT_GOLD_VERSION: // major * 100 + minor
82 gold_version = tv->tv_u.tv_val;
84 case LDPT_LINKER_OUTPUT:
85 switch (tv->tv_u.tv_val) {
88 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
90 case LDPO_EXEC: // .exe
91 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
94 (*message)(LDPL_ERROR, "Unknown output file type %d",
98 // TODO: add an option to disable PIC.
99 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
102 if (strcmp("generate-api-file", tv->tv_u.tv_string) == 0) {
103 generate_api_file = true;
105 (*message)(LDPL_WARNING, "Ignoring flag %s", tv->tv_u.tv_string);
108 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
109 ld_plugin_register_claim_file callback;
110 callback = tv->tv_u.tv_register_claim_file;
112 if ((*callback)(claim_file_hook) != LDPS_OK)
115 registeredClaimFile = true;
117 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
118 ld_plugin_register_all_symbols_read callback;
119 callback = tv->tv_u.tv_register_all_symbols_read;
121 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
124 registeredAllSymbolsRead = true;
126 case LDPT_REGISTER_CLEANUP_HOOK: {
127 ld_plugin_register_cleanup callback;
128 callback = tv->tv_u.tv_register_cleanup;
130 if ((*callback)(cleanup_hook) != LDPS_OK)
133 registeredCleanup = true;
135 case LDPT_ADD_SYMBOLS:
136 add_symbols = tv->tv_u.tv_add_symbols;
138 case LDPT_GET_SYMBOLS:
139 get_symbols = tv->tv_u.tv_get_symbols;
141 case LDPT_ADD_INPUT_FILE:
142 add_input_file = tv->tv_u.tv_add_input_file;
145 message = tv->tv_u.tv_message;
152 if (!registeredClaimFile) {
153 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
157 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
164 /// claim_file_hook - called by gold to see whether this file is one that
165 /// our plugin can handle. We'll try to open it and register all the symbols
166 /// with add_symbol if possible.
167 ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
171 // Gold has found what might be IR part-way inside of a file, such as
173 if (lseek(file->fd, file->offset, SEEK_SET) == -1) {
174 (*message)(LDPL_ERROR,
175 "Failed to seek to archive member of %s at offset %d: %s\n",
177 file->offset, strerror(errno));
180 buf = malloc(file->filesize);
182 (*message)(LDPL_ERROR,
183 "Failed to allocate buffer for archive member of size: %d\n",
187 if (read(file->fd, buf, file->filesize) != file->filesize) {
188 (*message)(LDPL_ERROR,
189 "Failed to read archive member of %s at offset %d: %s\n",
196 if (!lto_module_is_object_file_in_memory(buf, file->filesize)) {
200 } else if (!lto_module_is_object_file(file->name))
204 Modules.resize(Modules.size() + 1);
205 claimed_file &cf = Modules.back();
207 cf.M = buf ? lto_module_create_from_memory(buf, file->filesize) :
208 lto_module_create(file->name);
211 (*message)(LDPL_ERROR, "Failed to create LLVM module: %s",
212 lto_get_error_message());
215 cf.handle = file->handle;
216 unsigned sym_count = lto_module_get_num_symbols(cf.M);
217 cf.syms.reserve(sym_count);
219 for (unsigned i = 0; i != sym_count; ++i) {
220 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(cf.M, i);
221 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
224 cf.syms.push_back(ld_plugin_symbol());
225 ld_plugin_symbol &sym = cf.syms.back();
226 sym.name = const_cast<char *>(lto_module_get_symbol_name(cf.M, i));
229 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
231 case LTO_SYMBOL_SCOPE_HIDDEN:
232 sym.visibility = LDPV_HIDDEN;
234 case LTO_SYMBOL_SCOPE_PROTECTED:
235 sym.visibility = LDPV_PROTECTED;
238 case LTO_SYMBOL_SCOPE_DEFAULT:
239 sym.visibility = LDPV_DEFAULT;
242 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
246 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
247 switch (definition) {
248 case LTO_SYMBOL_DEFINITION_REGULAR:
251 case LTO_SYMBOL_DEFINITION_UNDEFINED:
252 sym.def = LDPK_UNDEF;
254 case LTO_SYMBOL_DEFINITION_TENTATIVE:
255 sym.def = LDPK_COMMON;
257 case LTO_SYMBOL_DEFINITION_WEAK:
258 sym.def = LDPK_WEAKDEF;
261 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
265 // LLVM never emits COMDAT.
267 sym.comdat_key = NULL;
269 sym.resolution = LDPR_UNKNOWN;
272 cf.syms.reserve(cf.syms.size());
274 if (!cf.syms.empty()) {
275 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
276 (*message)(LDPL_ERROR, "Unable to add symbols!");
284 /// all_symbols_read_hook - gold informs us that all symbols have been read.
285 /// At this point, we use get_symbols to see if any of our definitions have
286 /// been overridden by a native object file. Then, perform optimization and
288 ld_plugin_status all_symbols_read_hook(void) {
289 lto_code_gen_t cg = lto_codegen_create();
291 for (std::list<claimed_file>::iterator I = Modules.begin(),
292 E = Modules.end(); I != E; ++I)
293 lto_codegen_add_module(cg, I->M);
295 std::ofstream api_file;
296 if (generate_api_file) {
297 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
298 if (!api_file.is_open()) {
299 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
304 // If we don't preserve any symbols, libLTO will assume that all symbols are
305 // needed. Keep all symbols unless we're producing a final executable.
306 if (output_type == LTO_CODEGEN_PIC_MODEL_STATIC) {
307 bool anySymbolsPreserved = false;
308 for (std::list<claimed_file>::iterator I = Modules.begin(),
309 E = Modules.end(); I != E; ++I) {
310 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
311 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
312 if (I->syms[i].resolution == LDPR_PREVAILING_DEF ||
313 (I->syms[i].def == LDPK_COMMON &&
314 I->syms[i].resolution == LDPR_RESOLVED_IR)) {
315 lto_codegen_add_must_preserve_symbol(cg, I->syms[i].name);
316 anySymbolsPreserved = true;
318 if (generate_api_file)
319 api_file << I->syms[i].name << "\n";
324 if (generate_api_file)
327 if (!anySymbolsPreserved) {
328 // This entire file is unnecessary!
329 lto_codegen_dispose(cg);
334 lto_codegen_set_pic_model(cg, output_type);
335 lto_codegen_set_debug_model(cg, LTO_DEBUG_MODEL_DWARF);
338 const char *buffer = static_cast<const char *>(lto_codegen_compile(cg,
343 sys::Path uniqueObjPath("/tmp/llvmgold.o");
344 if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) {
345 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
348 raw_fd_ostream *objFile = new raw_fd_ostream(uniqueObjPath.c_str(), true,
350 if (!ErrMsg.empty()) {
352 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
356 objFile->write(buffer, bufsize);
359 lto_codegen_dispose(cg);
361 if ((*add_input_file)(const_cast<char*>(uniqueObjPath.c_str())) != LDPS_OK) {
362 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
363 (*message)(LDPL_ERROR, "File left behind in: %s", uniqueObjPath.c_str());
367 Cleanup.push_back(uniqueObjPath);
372 ld_plugin_status cleanup_hook(void) {
375 for (int i = 0, e = Cleanup.size(); i != e; ++i)
376 if (Cleanup[i].eraseFromDisk(false, &ErrMsg))
377 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),