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" // plugin-api.h requires HAVE_STDINT_H
16 #include "llvm-c/lto.h"
17 #include "llvm/ADT/StringSet.h"
18 #include "llvm/Support/Errno.h"
19 #include "llvm/Support/FileSystem.h"
20 #include "llvm/Support/MemoryBuffer.h"
21 #include "llvm/Support/Path.h"
22 #include "llvm/Support/Program.h"
23 #include "llvm/Support/ToolOutputFile.h"
29 #include <plugin-api.h>
30 #include <system_error>
33 // Support Windows/MinGW crazyness.
41 // FIXME: remove this declaration when we stop maintaining Ubuntu Quantal and
42 // Precise and Debian Wheezy (binutils 2.23 is required)
47 using std::error_code;
50 ld_plugin_status discard_message(int level, const char *format, ...) {
51 // Die loudly. Recent versions of Gold pass ld_plugin_message as the first
52 // callback in the transfer vector. This should never be called.
56 ld_plugin_add_symbols add_symbols = NULL;
57 ld_plugin_get_symbols get_symbols = NULL;
58 ld_plugin_add_input_file add_input_file = NULL;
59 ld_plugin_add_input_library add_input_library = NULL;
60 ld_plugin_set_extra_library_path set_extra_library_path = NULL;
61 ld_plugin_get_view get_view = NULL;
62 ld_plugin_message message = discard_message;
69 std::vector<ld_plugin_symbol> syms;
72 lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
73 std::string output_name = "";
74 std::list<claimed_file> Modules;
75 std::vector<std::string> Cleanup;
76 lto_code_gen_t code_gen = NULL;
77 StringSet<> CannotBeHidden;
81 enum generate_bc { BC_NO, BC_ALSO, BC_ONLY };
82 static bool generate_api_file = false;
83 static generate_bc generate_bc_file = BC_NO;
84 static std::string bc_path;
85 static std::string obj_path;
86 static std::string extra_library_path;
87 static std::string triple;
88 static std::string mcpu;
89 // Additional options to pass into the code generator.
90 // Note: This array will contain all plugin options which are not claimed
91 // as plugin exclusive to pass to the code generator.
92 // For example, "generate-api-file" and "as"options are for the plugin
93 // use only and will not be passed.
94 static std::vector<std::string> extra;
96 static void process_plugin_option(const char* opt_)
100 llvm::StringRef opt = opt_;
102 if (opt == "generate-api-file") {
103 generate_api_file = true;
104 } else if (opt.startswith("mcpu=")) {
105 mcpu = opt.substr(strlen("mcpu="));
106 } else if (opt.startswith("extra-library-path=")) {
107 extra_library_path = opt.substr(strlen("extra_library_path="));
108 } else if (opt.startswith("mtriple=")) {
109 triple = opt.substr(strlen("mtriple="));
110 } else if (opt.startswith("obj-path=")) {
111 obj_path = opt.substr(strlen("obj-path="));
112 } else if (opt == "emit-llvm") {
113 generate_bc_file = BC_ONLY;
114 } else if (opt == "also-emit-llvm") {
115 generate_bc_file = BC_ALSO;
116 } else if (opt.startswith("also-emit-llvm=")) {
117 llvm::StringRef path = opt.substr(strlen("also-emit-llvm="));
118 generate_bc_file = BC_ALSO;
119 if (!bc_path.empty()) {
120 (*message)(LDPL_WARNING, "Path to the output IL file specified twice. "
121 "Discarding %s", opt_);
126 // Save this option to pass to the code generator.
127 extra.push_back(opt);
132 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
134 static ld_plugin_status all_symbols_read_hook(void);
135 static ld_plugin_status cleanup_hook(void);
137 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
138 ld_plugin_status onload(ld_plugin_tv *tv) {
139 // We're given a pointer to the first transfer vector. We read through them
140 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
141 // contain pointers to functions that we need to call to register our own
142 // hooks. The others are addresses of functions we can use to call into gold
145 bool registeredClaimFile = false;
147 for (; tv->tv_tag != LDPT_NULL; ++tv) {
148 switch (tv->tv_tag) {
149 case LDPT_API_VERSION:
150 api_version = tv->tv_u.tv_val;
152 case LDPT_GOLD_VERSION: // major * 100 + minor
153 gold_version = tv->tv_u.tv_val;
155 case LDPT_OUTPUT_NAME:
156 output_name = tv->tv_u.tv_string;
158 case LDPT_LINKER_OUTPUT:
159 switch (tv->tv_u.tv_val) {
161 case LDPO_DYN: // .so
162 case LDPO_PIE: // position independent executable
163 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
165 case LDPO_EXEC: // .exe
166 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
169 (*message)(LDPL_ERROR, "Unknown output file type %d",
173 // TODO: add an option to disable PIC.
174 //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
177 options::process_plugin_option(tv->tv_u.tv_string);
179 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
180 ld_plugin_register_claim_file callback;
181 callback = tv->tv_u.tv_register_claim_file;
183 if ((*callback)(claim_file_hook) != LDPS_OK)
186 registeredClaimFile = true;
188 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
189 ld_plugin_register_all_symbols_read callback;
190 callback = tv->tv_u.tv_register_all_symbols_read;
192 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
195 code_gen = lto_codegen_create();
197 case LDPT_REGISTER_CLEANUP_HOOK: {
198 ld_plugin_register_cleanup callback;
199 callback = tv->tv_u.tv_register_cleanup;
201 if ((*callback)(cleanup_hook) != LDPS_OK)
204 case LDPT_ADD_SYMBOLS:
205 add_symbols = tv->tv_u.tv_add_symbols;
207 case LDPT_GET_SYMBOLS_V2:
208 get_symbols = tv->tv_u.tv_get_symbols;
210 case LDPT_ADD_INPUT_FILE:
211 add_input_file = tv->tv_u.tv_add_input_file;
213 case LDPT_ADD_INPUT_LIBRARY:
214 add_input_library = tv->tv_u.tv_add_input_file;
216 case LDPT_SET_EXTRA_LIBRARY_PATH:
217 set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
220 get_view = tv->tv_u.tv_get_view;
223 message = tv->tv_u.tv_message;
230 if (!registeredClaimFile) {
231 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
235 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
242 /// claim_file_hook - called by gold to see whether this file is one that
243 /// our plugin can handle. We'll try to open it and register all the symbols
244 /// with add_symbol if possible.
245 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
249 std::unique_ptr<MemoryBuffer> buffer;
251 if (get_view(file->handle, &view) != LDPS_OK) {
252 (*message)(LDPL_ERROR, "Failed to get a view of %s", file->name);
257 // Gold has found what might be IR part-way inside of a file, such as
260 offset = file->offset;
262 if (error_code ec = MemoryBuffer::getOpenFileSlice(
263 file->fd, file->name, buffer, file->filesize, offset)) {
264 (*message)(LDPL_ERROR, ec.message().c_str());
267 view = buffer->getBufferStart();
270 if (!lto_module_is_object_file_in_memory(view, file->filesize))
273 M = lto_module_create_from_memory(view, file->filesize);
275 if (const char* msg = lto_get_error_message()) {
276 (*message)(LDPL_ERROR,
277 "LLVM gold plugin has failed to create LTO module: %s",
285 Modules.resize(Modules.size() + 1);
286 claimed_file &cf = Modules.back();
288 if (!options::triple.empty())
289 lto_module_set_target_triple(M, options::triple.c_str());
291 cf.handle = file->handle;
292 unsigned sym_count = lto_module_get_num_symbols(M);
293 cf.syms.reserve(sym_count);
295 for (unsigned i = 0; i != sym_count; ++i) {
296 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(M, i);
297 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
300 cf.syms.push_back(ld_plugin_symbol());
301 ld_plugin_symbol &sym = cf.syms.back();
302 sym.name = const_cast<char *>(lto_module_get_symbol_name(M, i));
303 sym.name = strdup(sym.name);
306 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
307 bool CanBeHidden = scope == LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN;
309 CannotBeHidden.insert(sym.name);
311 case LTO_SYMBOL_SCOPE_HIDDEN:
312 sym.visibility = LDPV_HIDDEN;
314 case LTO_SYMBOL_SCOPE_PROTECTED:
315 sym.visibility = LDPV_PROTECTED;
318 case LTO_SYMBOL_SCOPE_DEFAULT:
319 case LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN:
320 sym.visibility = LDPV_DEFAULT;
323 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
327 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
328 sym.comdat_key = NULL;
329 switch (definition) {
330 case LTO_SYMBOL_DEFINITION_REGULAR:
333 case LTO_SYMBOL_DEFINITION_UNDEFINED:
334 sym.def = LDPK_UNDEF;
336 case LTO_SYMBOL_DEFINITION_TENTATIVE:
337 sym.def = LDPK_COMMON;
339 case LTO_SYMBOL_DEFINITION_WEAK:
340 sym.comdat_key = sym.name;
341 sym.def = LDPK_WEAKDEF;
343 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
344 sym.def = LDPK_WEAKUNDEF;
347 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
353 sym.resolution = LDPR_UNKNOWN;
356 cf.syms.reserve(cf.syms.size());
358 if (!cf.syms.empty()) {
359 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
360 (*message)(LDPL_ERROR, "Unable to add symbols!");
366 if (lto_codegen_add_module(code_gen, M)) {
367 (*message)(LDPL_ERROR, "Error linking module: %s",
368 lto_get_error_message());
373 lto_module_dispose(M);
378 static bool mustPreserve(const claimed_file &F, int i) {
379 if (F.syms[i].resolution == LDPR_PREVAILING_DEF)
381 if (F.syms[i].resolution == LDPR_PREVAILING_DEF_IRONLY_EXP)
382 return CannotBeHidden.count(F.syms[i].name);
386 /// all_symbols_read_hook - gold informs us that all symbols have been read.
387 /// At this point, we use get_symbols to see if any of our definitions have
388 /// been overridden by a native object file. Then, perform optimization and
390 static ld_plugin_status all_symbols_read_hook(void) {
391 std::ofstream api_file;
394 if (options::generate_api_file) {
395 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
396 if (!api_file.is_open()) {
397 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
402 for (std::list<claimed_file>::iterator I = Modules.begin(),
403 E = Modules.end(); I != E; ++I) {
406 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
407 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
408 if (mustPreserve(*I, i)) {
409 lto_codegen_add_must_preserve_symbol(code_gen, I->syms[i].name);
411 if (options::generate_api_file)
412 api_file << I->syms[i].name << "\n";
417 if (options::generate_api_file)
420 lto_codegen_set_pic_model(code_gen, output_type);
421 lto_codegen_set_debug_model(code_gen, LTO_DEBUG_MODEL_DWARF);
422 if (!options::mcpu.empty())
423 lto_codegen_set_cpu(code_gen, options::mcpu.c_str());
425 // Pass through extra options to the code generator.
426 if (!options::extra.empty()) {
427 for (std::vector<std::string>::iterator it = options::extra.begin();
428 it != options::extra.end(); ++it) {
429 lto_codegen_debug_options(code_gen, (*it).c_str());
433 if (options::generate_bc_file != options::BC_NO) {
435 if (options::generate_bc_file == options::BC_ONLY)
437 else if (!options::bc_path.empty())
438 path = options::bc_path;
440 path = output_name + ".bc";
441 bool err = lto_codegen_write_merged_modules(code_gen, path.c_str());
443 (*message)(LDPL_FATAL, "Failed to write the output file.");
444 if (options::generate_bc_file == options::BC_ONLY) {
445 lto_codegen_dispose(code_gen);
453 if (lto_codegen_compile_to_file(code_gen, &Temp)) {
454 (*message)(LDPL_ERROR, "Could not produce a combined object file\n");
459 lto_codegen_dispose(code_gen);
460 for (std::list<claimed_file>::iterator I = Modules.begin(),
461 E = Modules.end(); I != E; ++I) {
462 for (unsigned i = 0; i != I->syms.size(); ++i) {
463 ld_plugin_symbol &sym = I->syms[i];
468 if ((*add_input_file)(ObjPath.c_str()) != LDPS_OK) {
469 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
470 (*message)(LDPL_ERROR, "File left behind in: %s", ObjPath.c_str());
474 if (!options::extra_library_path.empty() &&
475 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) {
476 (*message)(LDPL_ERROR, "Unable to set the extra library path.");
480 if (options::obj_path.empty())
481 Cleanup.push_back(ObjPath);
486 static ld_plugin_status cleanup_hook(void) {
487 for (int i = 0, e = Cleanup.size(); i != e; ++i) {
488 error_code EC = sys::fs::remove(Cleanup[i]);
490 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),
491 EC.message().c_str());