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 "llvm/Config/config.h"
16 #include "plugin-api.h"
18 #include "llvm-c/lto.h"
20 #include "llvm/Support/ToolOutputFile.h"
21 #include "llvm/System/Errno.h"
22 #include "llvm/System/Path.h"
23 #include "llvm/System/Program.h"
35 ld_plugin_status discard_message(int level, const char *format, ...) {
36 // Die loudly. Recent versions of Gold pass ld_plugin_message as the first
37 // callback in the transfer vector. This should never be called.
41 ld_plugin_add_symbols add_symbols = NULL;
42 ld_plugin_get_symbols get_symbols = NULL;
43 ld_plugin_add_input_file add_input_file = NULL;
44 ld_plugin_add_input_library add_input_library = NULL;
45 ld_plugin_set_extra_library_path set_extra_library_path = NULL;
46 ld_plugin_message message = discard_message;
54 std::vector<ld_plugin_symbol> syms;
57 lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
58 std::string output_name = "";
59 std::list<claimed_file> Modules;
60 std::vector<sys::Path> Cleanup;
64 enum generate_bc { BC_NO, BC_ALSO, BC_ONLY };
65 static bool generate_api_file = false;
66 static generate_bc generate_bc_file = BC_NO;
67 static std::string bc_path;
68 static std::string as_path;
69 static std::vector<std::string> as_args;
70 static std::vector<std::string> pass_through;
71 static std::string extra_library_path;
72 static std::string triple;
73 static std::string mcpu;
74 // Additional options to pass into the code generator.
75 // Note: This array will contain all plugin options which are not claimed
76 // as plugin exclusive to pass to the code generator.
77 // For example, "generate-api-file" and "as"options are for the plugin
78 // use only and will not be passed.
79 static std::vector<std::string> extra;
81 static void process_plugin_option(const char* opt_)
85 llvm::StringRef opt = opt_;
87 if (opt == "generate-api-file") {
88 generate_api_file = true;
89 } else if (opt.startswith("mcpu=")) {
90 mcpu = opt.substr(strlen("mcpu="));
91 } else if (opt.startswith("as=")) {
92 if (!as_path.empty()) {
93 (*message)(LDPL_WARNING, "Path to as specified twice. "
94 "Discarding %s", opt_);
96 as_path = opt.substr(strlen("as="));
98 } else if (opt.startswith("as-arg=")) {
99 llvm::StringRef item = opt.substr(strlen("as-arg="));
100 as_args.push_back(item.str());
101 } else if (opt.startswith("extra-library-path=")) {
102 extra_library_path = opt.substr(strlen("extra_library_path="));
103 } else if (opt.startswith("pass-through=")) {
104 llvm::StringRef item = opt.substr(strlen("pass-through="));
105 pass_through.push_back(item.str());
106 } else if (opt.startswith("mtriple=")) {
107 triple = opt.substr(strlen("mtriple="));
108 } else if (opt == "emit-llvm") {
109 generate_bc_file = BC_ONLY;
110 } else if (opt == "also-emit-llvm") {
111 generate_bc_file = BC_ALSO;
112 } else if (opt.startswith("also-emit-llvm=")) {
113 llvm::StringRef path = opt.substr(strlen("also-emit-llvm="));
114 generate_bc_file = BC_ALSO;
115 if (!bc_path.empty()) {
116 (*message)(LDPL_WARNING, "Path to the output IL file specified twice. "
117 "Discarding %s", opt_);
122 // Save this option to pass to the code generator.
123 extra.push_back(opt);
128 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
130 static ld_plugin_status all_symbols_read_hook(void);
131 static ld_plugin_status cleanup_hook(void);
133 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
134 ld_plugin_status onload(ld_plugin_tv *tv) {
135 // We're given a pointer to the first transfer vector. We read through them
136 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
137 // contain pointers to functions that we need to call to register our own
138 // hooks. The others are addresses of functions we can use to call into gold
141 bool registeredClaimFile = false;
143 for (; tv->tv_tag != LDPT_NULL; ++tv) {
144 switch (tv->tv_tag) {
145 case LDPT_API_VERSION:
146 api_version = tv->tv_u.tv_val;
148 case LDPT_GOLD_VERSION: // major * 100 + minor
149 gold_version = tv->tv_u.tv_val;
151 case LDPT_OUTPUT_NAME:
152 output_name = tv->tv_u.tv_string;
154 case LDPT_LINKER_OUTPUT:
155 switch (tv->tv_u.tv_val) {
157 case LDPO_DYN: // .so
158 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
160 case LDPO_EXEC: // .exe
161 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
164 (*message)(LDPL_ERROR, "Unknown output file type %d",
168 // TODO: add an option to disable PIC.
169 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
172 options::process_plugin_option(tv->tv_u.tv_string);
174 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
175 ld_plugin_register_claim_file callback;
176 callback = tv->tv_u.tv_register_claim_file;
178 if ((*callback)(claim_file_hook) != LDPS_OK)
181 registeredClaimFile = true;
183 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
184 ld_plugin_register_all_symbols_read callback;
185 callback = tv->tv_u.tv_register_all_symbols_read;
187 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
190 case LDPT_REGISTER_CLEANUP_HOOK: {
191 ld_plugin_register_cleanup callback;
192 callback = tv->tv_u.tv_register_cleanup;
194 if ((*callback)(cleanup_hook) != LDPS_OK)
197 case LDPT_ADD_SYMBOLS:
198 add_symbols = tv->tv_u.tv_add_symbols;
200 case LDPT_GET_SYMBOLS:
201 get_symbols = tv->tv_u.tv_get_symbols;
203 case LDPT_ADD_INPUT_FILE:
204 add_input_file = tv->tv_u.tv_add_input_file;
206 case LDPT_ADD_INPUT_LIBRARY:
207 add_input_library = tv->tv_u.tv_add_input_file;
209 case LDPT_SET_EXTRA_LIBRARY_PATH:
210 set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
213 message = tv->tv_u.tv_message;
220 if (!registeredClaimFile) {
221 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
225 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
232 /// claim_file_hook - called by gold to see whether this file is one that
233 /// our plugin can handle. We'll try to open it and register all the symbols
234 /// with add_symbol if possible.
235 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
239 // Gold has found what might be IR part-way inside of a file, such as
241 if (lseek(file->fd, file->offset, SEEK_SET) == -1) {
242 (*message)(LDPL_ERROR,
243 "Failed to seek to archive member of %s at offset %d: %s\n",
245 file->offset, sys::StrError(errno).c_str());
248 buf = malloc(file->filesize);
250 (*message)(LDPL_ERROR,
251 "Failed to allocate buffer for archive member of size: %d\n",
255 if (read(file->fd, buf, file->filesize) != file->filesize) {
256 (*message)(LDPL_ERROR,
257 "Failed to read archive member of %s at offset %d: %s\n",
260 sys::StrError(errno).c_str());
264 if (!lto_module_is_object_file_in_memory(buf, file->filesize)) {
268 } else if (!lto_module_is_object_file(file->name))
272 Modules.resize(Modules.size() + 1);
273 claimed_file &cf = Modules.back();
275 cf.M = buf ? lto_module_create_from_memory(buf, file->filesize) :
276 lto_module_create(file->name);
279 (*message)(LDPL_ERROR, "Failed to create LLVM module: %s",
280 lto_get_error_message());
284 if (!options::triple.empty())
285 lto_module_set_target_triple(cf.M, options::triple.c_str());
287 cf.handle = file->handle;
288 unsigned sym_count = lto_module_get_num_symbols(cf.M);
289 cf.syms.reserve(sym_count);
291 for (unsigned i = 0; i != sym_count; ++i) {
292 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(cf.M, i);
293 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
296 cf.syms.push_back(ld_plugin_symbol());
297 ld_plugin_symbol &sym = cf.syms.back();
298 sym.name = const_cast<char *>(lto_module_get_symbol_name(cf.M, i));
301 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
303 case LTO_SYMBOL_SCOPE_HIDDEN:
304 sym.visibility = LDPV_HIDDEN;
306 case LTO_SYMBOL_SCOPE_PROTECTED:
307 sym.visibility = LDPV_PROTECTED;
310 case LTO_SYMBOL_SCOPE_DEFAULT:
311 sym.visibility = LDPV_DEFAULT;
314 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
318 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
319 switch (definition) {
320 case LTO_SYMBOL_DEFINITION_REGULAR:
323 case LTO_SYMBOL_DEFINITION_UNDEFINED:
324 sym.def = LDPK_UNDEF;
326 case LTO_SYMBOL_DEFINITION_TENTATIVE:
327 sym.def = LDPK_COMMON;
329 case LTO_SYMBOL_DEFINITION_WEAK:
330 sym.def = LDPK_WEAKDEF;
332 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
333 sym.def = LDPK_WEAKUNDEF;
336 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
340 // LLVM never emits COMDAT.
342 sym.comdat_key = NULL;
344 sym.resolution = LDPR_UNKNOWN;
347 cf.syms.reserve(cf.syms.size());
349 if (!cf.syms.empty()) {
350 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
351 (*message)(LDPL_ERROR, "Unable to add symbols!");
359 /// all_symbols_read_hook - gold informs us that all symbols have been read.
360 /// At this point, we use get_symbols to see if any of our definitions have
361 /// been overridden by a native object file. Then, perform optimization and
363 static ld_plugin_status all_symbols_read_hook(void) {
364 lto_code_gen_t cg = lto_codegen_create();
366 for (std::list<claimed_file>::iterator I = Modules.begin(),
367 E = Modules.end(); I != E; ++I)
368 lto_codegen_add_module(cg, I->M);
370 std::ofstream api_file;
371 if (options::generate_api_file) {
372 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
373 if (!api_file.is_open()) {
374 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
379 // If we don't preserve any symbols, libLTO will assume that all symbols are
380 // needed. Keep all symbols unless we're producing a final executable.
381 bool anySymbolsPreserved = false;
382 for (std::list<claimed_file>::iterator I = Modules.begin(),
383 E = Modules.end(); I != E; ++I) {
384 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
385 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
386 if (I->syms[i].resolution == LDPR_PREVAILING_DEF) {
387 lto_codegen_add_must_preserve_symbol(cg, I->syms[i].name);
388 anySymbolsPreserved = true;
390 if (options::generate_api_file)
391 api_file << I->syms[i].name << "\n";
396 if (options::generate_api_file)
399 if (!anySymbolsPreserved) {
400 // All of the IL is unnecessary!
401 lto_codegen_dispose(cg);
405 lto_codegen_set_pic_model(cg, output_type);
406 lto_codegen_set_debug_model(cg, LTO_DEBUG_MODEL_DWARF);
407 if (!options::as_path.empty()) {
408 sys::Path p = sys::Program::FindProgramByName(options::as_path);
409 lto_codegen_set_assembler_path(cg, p.c_str());
411 if (!options::as_args.empty()) {
412 std::vector<const char *> as_args_p;
413 for (std::vector<std::string>::iterator I = options::as_args.begin(),
414 E = options::as_args.end(); I != E; ++I) {
415 as_args_p.push_back(I->c_str());
417 lto_codegen_set_assembler_args(cg, &as_args_p[0], as_args_p.size());
419 if (!options::mcpu.empty())
420 lto_codegen_set_cpu(cg, options::mcpu.c_str());
422 // Pass through extra options to the code generator.
423 if (!options::extra.empty()) {
424 for (std::vector<std::string>::iterator it = options::extra.begin();
425 it != options::extra.end(); ++it) {
426 lto_codegen_debug_options(cg, (*it).c_str());
431 if (options::generate_bc_file != options::BC_NO) {
433 if (options::generate_bc_file == options::BC_ONLY)
435 else if (!options::bc_path.empty())
436 path = options::bc_path;
438 path = output_name + ".bc";
439 bool err = lto_codegen_write_merged_modules(cg, path.c_str());
441 (*message)(LDPL_FATAL, "Failed to write the output file.");
442 if (options::generate_bc_file == options::BC_ONLY)
446 const char *buffer = static_cast<const char *>(lto_codegen_compile(cg,
451 sys::Path uniqueObjPath("/tmp/llvmgold.o");
452 if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) {
453 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
456 tool_output_file objFile(uniqueObjPath.c_str(), ErrMsg,
457 raw_fd_ostream::F_Binary);
458 if (!ErrMsg.empty()) {
459 (*message)(LDPL_ERROR, "%s", ErrMsg.c_str());
463 objFile.os().write(buffer, bufsize);
464 objFile.os().close();
465 if (objFile.os().has_error()) {
466 (*message)(LDPL_ERROR, "Error writing output file '%s'",
467 uniqueObjPath.c_str());
468 objFile.os().clear_error();
473 lto_codegen_dispose(cg);
475 if ((*add_input_file)(uniqueObjPath.c_str()) != LDPS_OK) {
476 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
477 (*message)(LDPL_ERROR, "File left behind in: %s", uniqueObjPath.c_str());
481 if (!options::extra_library_path.empty() &&
482 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) {
483 (*message)(LDPL_ERROR, "Unable to set the extra library path.");
487 for (std::vector<std::string>::iterator i = options::pass_through.begin(),
488 e = options::pass_through.end();
490 std::string &item = *i;
491 const char *item_p = item.c_str();
492 if (llvm::StringRef(item).startswith("-l")) {
493 if (add_input_library(item_p + 2) != LDPS_OK) {
494 (*message)(LDPL_ERROR, "Unable to add library to the link.");
498 if (add_input_file(item_p) != LDPS_OK) {
499 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
505 Cleanup.push_back(uniqueObjPath);
510 static ld_plugin_status cleanup_hook(void) {
513 for (int i = 0, e = Cleanup.size(); i != e; ++i)
514 if (Cleanup[i].eraseFromDisk(false, &ErrMsg))
515 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),