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;
52 std::vector<ld_plugin_symbol> syms;
55 lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
56 std::list<claimed_file> Modules;
57 std::vector<sys::Path> Cleanup;
60 ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
62 ld_plugin_status all_symbols_read_hook(void);
63 ld_plugin_status cleanup_hook(void);
65 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
66 ld_plugin_status onload(ld_plugin_tv *tv) {
67 // We're given a pointer to the first transfer vector. We read through them
68 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
69 // contain pointers to functions that we need to call to register our own
70 // hooks. The others are addresses of functions we can use to call into gold
73 bool registeredClaimFile = false;
74 bool registeredAllSymbolsRead = false;
75 bool registeredCleanup = false;
77 for (; tv->tv_tag != LDPT_NULL; ++tv) {
79 case LDPT_API_VERSION:
80 api_version = tv->tv_u.tv_val;
82 case LDPT_GOLD_VERSION: // major * 100 + minor
83 gold_version = tv->tv_u.tv_val;
85 case LDPT_LINKER_OUTPUT:
86 switch (tv->tv_u.tv_val) {
89 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
91 case LDPO_EXEC: // .exe
92 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
95 (*message)(LDPL_ERROR, "Unknown output file type %d",
99 // TODO: add an option to disable PIC.
100 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
103 if (strcmp("generate-api-file", tv->tv_u.tv_string) == 0) {
104 generate_api_file = true;
105 } else if (strncmp("gcc=", tv->tv_u.tv_string, 4) == 0) {
107 (*message)(LDPL_WARNING, "Path to gcc specified twice. "
108 "Discarding %s", tv->tv_u.tv_string);
110 gcc_path = strdup(tv->tv_u.tv_string + 4);
113 (*message)(LDPL_WARNING, "Ignoring flag %s", tv->tv_u.tv_string);
116 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
117 ld_plugin_register_claim_file callback;
118 callback = tv->tv_u.tv_register_claim_file;
120 if ((*callback)(claim_file_hook) != LDPS_OK)
123 registeredClaimFile = true;
125 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
126 ld_plugin_register_all_symbols_read callback;
127 callback = tv->tv_u.tv_register_all_symbols_read;
129 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
132 registeredAllSymbolsRead = true;
134 case LDPT_REGISTER_CLEANUP_HOOK: {
135 ld_plugin_register_cleanup callback;
136 callback = tv->tv_u.tv_register_cleanup;
138 if ((*callback)(cleanup_hook) != LDPS_OK)
141 registeredCleanup = true;
143 case LDPT_ADD_SYMBOLS:
144 add_symbols = tv->tv_u.tv_add_symbols;
146 case LDPT_GET_SYMBOLS:
147 get_symbols = tv->tv_u.tv_get_symbols;
149 case LDPT_ADD_INPUT_FILE:
150 add_input_file = tv->tv_u.tv_add_input_file;
153 message = tv->tv_u.tv_message;
160 if (!registeredClaimFile) {
161 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
165 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
172 /// claim_file_hook - called by gold to see whether this file is one that
173 /// our plugin can handle. We'll try to open it and register all the symbols
174 /// with add_symbol if possible.
175 ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
179 // Gold has found what might be IR part-way inside of a file, such as
181 if (lseek(file->fd, file->offset, SEEK_SET) == -1) {
182 (*message)(LDPL_ERROR,
183 "Failed to seek to archive member of %s at offset %d: %s\n",
185 file->offset, strerror(errno));
188 buf = malloc(file->filesize);
190 (*message)(LDPL_ERROR,
191 "Failed to allocate buffer for archive member of size: %d\n",
195 if (read(file->fd, buf, file->filesize) != file->filesize) {
196 (*message)(LDPL_ERROR,
197 "Failed to read archive member of %s at offset %d: %s\n",
204 if (!lto_module_is_object_file_in_memory(buf, file->filesize)) {
208 } else if (!lto_module_is_object_file(file->name))
212 Modules.resize(Modules.size() + 1);
213 claimed_file &cf = Modules.back();
215 cf.M = buf ? lto_module_create_from_memory(buf, file->filesize) :
216 lto_module_create(file->name);
219 (*message)(LDPL_ERROR, "Failed to create LLVM module: %s",
220 lto_get_error_message());
223 cf.handle = file->handle;
224 unsigned sym_count = lto_module_get_num_symbols(cf.M);
225 cf.syms.reserve(sym_count);
227 for (unsigned i = 0; i != sym_count; ++i) {
228 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(cf.M, i);
229 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
232 cf.syms.push_back(ld_plugin_symbol());
233 ld_plugin_symbol &sym = cf.syms.back();
234 sym.name = const_cast<char *>(lto_module_get_symbol_name(cf.M, i));
237 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
239 case LTO_SYMBOL_SCOPE_HIDDEN:
240 sym.visibility = LDPV_HIDDEN;
242 case LTO_SYMBOL_SCOPE_PROTECTED:
243 sym.visibility = LDPV_PROTECTED;
246 case LTO_SYMBOL_SCOPE_DEFAULT:
247 sym.visibility = LDPV_DEFAULT;
250 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
254 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
255 switch (definition) {
256 case LTO_SYMBOL_DEFINITION_REGULAR:
259 case LTO_SYMBOL_DEFINITION_UNDEFINED:
260 sym.def = LDPK_UNDEF;
262 case LTO_SYMBOL_DEFINITION_TENTATIVE:
263 sym.def = LDPK_COMMON;
265 case LTO_SYMBOL_DEFINITION_WEAK:
266 sym.def = LDPK_WEAKDEF;
268 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
269 sym.def = LDPK_WEAKUNDEF;
272 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
276 // LLVM never emits COMDAT.
278 sym.comdat_key = NULL;
280 sym.resolution = LDPR_UNKNOWN;
283 cf.syms.reserve(cf.syms.size());
285 if (!cf.syms.empty()) {
286 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
287 (*message)(LDPL_ERROR, "Unable to add symbols!");
295 /// all_symbols_read_hook - gold informs us that all symbols have been read.
296 /// At this point, we use get_symbols to see if any of our definitions have
297 /// been overridden by a native object file. Then, perform optimization and
299 ld_plugin_status all_symbols_read_hook(void) {
300 lto_code_gen_t cg = lto_codegen_create();
302 for (std::list<claimed_file>::iterator I = Modules.begin(),
303 E = Modules.end(); I != E; ++I)
304 lto_codegen_add_module(cg, I->M);
306 std::ofstream api_file;
307 if (generate_api_file) {
308 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
309 if (!api_file.is_open()) {
310 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
315 // If we don't preserve any symbols, libLTO will assume that all symbols are
316 // needed. Keep all symbols unless we're producing a final executable.
317 if (output_type == LTO_CODEGEN_PIC_MODEL_STATIC) {
318 bool anySymbolsPreserved = false;
319 for (std::list<claimed_file>::iterator I = Modules.begin(),
320 E = Modules.end(); I != E; ++I) {
321 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
322 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
323 if (I->syms[i].resolution == LDPR_PREVAILING_DEF ||
324 (I->syms[i].def == LDPK_COMMON &&
325 I->syms[i].resolution == LDPR_RESOLVED_IR)) {
326 lto_codegen_add_must_preserve_symbol(cg, I->syms[i].name);
327 anySymbolsPreserved = true;
329 if (generate_api_file)
330 api_file << I->syms[i].name << "\n";
335 if (generate_api_file)
338 if (!anySymbolsPreserved) {
339 // This entire file is unnecessary!
340 lto_codegen_dispose(cg);
345 lto_codegen_set_pic_model(cg, output_type);
346 lto_codegen_set_debug_model(cg, LTO_DEBUG_MODEL_DWARF);
348 lto_codegen_set_gcc_path(cg, gcc_path);
351 const char *buffer = static_cast<const char *>(lto_codegen_compile(cg,
356 sys::Path uniqueObjPath("/tmp/llvmgold.o");
357 if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) {
358 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
361 raw_fd_ostream *objFile = new raw_fd_ostream(uniqueObjPath.c_str(), true,
363 if (!ErrMsg.empty()) {
365 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
369 objFile->write(buffer, bufsize);
372 lto_codegen_dispose(cg);
374 if ((*add_input_file)(const_cast<char*>(uniqueObjPath.c_str())) != LDPS_OK) {
375 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
376 (*message)(LDPL_ERROR, "File left behind in: %s", uniqueObjPath.c_str());
380 Cleanup.push_back(uniqueObjPath);
385 ld_plugin_status cleanup_hook(void) {
388 for (int i = 0, e = Cleanup.size(); i != e; ++i)
389 if (Cleanup[i].eraseFromDisk(false, &ErrMsg))
390 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),