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)
49 ld_plugin_status discard_message(int level, const char *format, ...) {
50 // Die loudly. Recent versions of Gold pass ld_plugin_message as the first
51 // callback in the transfer vector. This should never be called.
55 ld_plugin_add_symbols add_symbols = NULL;
56 ld_plugin_get_symbols get_symbols = NULL;
57 ld_plugin_add_input_file add_input_file = NULL;
58 ld_plugin_add_input_library add_input_library = NULL;
59 ld_plugin_set_extra_library_path set_extra_library_path = NULL;
60 ld_plugin_get_view get_view = NULL;
61 ld_plugin_message message = discard_message;
68 std::vector<ld_plugin_symbol> syms;
71 lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
72 std::string output_name = "";
73 std::list<claimed_file> Modules;
74 std::vector<std::string> Cleanup;
75 lto_code_gen_t code_gen = NULL;
76 StringSet<> CannotBeHidden;
80 enum generate_bc { BC_NO, BC_ALSO, BC_ONLY };
81 static bool generate_api_file = false;
82 static generate_bc generate_bc_file = BC_NO;
83 static std::string bc_path;
84 static std::string obj_path;
85 static std::string extra_library_path;
86 static std::string triple;
87 static std::string mcpu;
88 // Additional options to pass into the code generator.
89 // Note: This array will contain all plugin options which are not claimed
90 // as plugin exclusive to pass to the code generator.
91 // For example, "generate-api-file" and "as"options are for the plugin
92 // use only and will not be passed.
93 static std::vector<std::string> extra;
95 static void process_plugin_option(const char* opt_)
99 llvm::StringRef opt = opt_;
101 if (opt == "generate-api-file") {
102 generate_api_file = true;
103 } else if (opt.startswith("mcpu=")) {
104 mcpu = opt.substr(strlen("mcpu="));
105 } else if (opt.startswith("extra-library-path=")) {
106 extra_library_path = opt.substr(strlen("extra_library_path="));
107 } else if (opt.startswith("mtriple=")) {
108 triple = opt.substr(strlen("mtriple="));
109 } else if (opt.startswith("obj-path=")) {
110 obj_path = opt.substr(strlen("obj-path="));
111 } else if (opt == "emit-llvm") {
112 generate_bc_file = BC_ONLY;
113 } else if (opt == "also-emit-llvm") {
114 generate_bc_file = BC_ALSO;
115 } else if (opt.startswith("also-emit-llvm=")) {
116 llvm::StringRef path = opt.substr(strlen("also-emit-llvm="));
117 generate_bc_file = BC_ALSO;
118 if (!bc_path.empty()) {
119 (*message)(LDPL_WARNING, "Path to the output IL file specified twice. "
120 "Discarding %s", opt_);
125 // Save this option to pass to the code generator.
126 extra.push_back(opt);
131 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
133 static ld_plugin_status all_symbols_read_hook(void);
134 static ld_plugin_status cleanup_hook(void);
136 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
137 ld_plugin_status onload(ld_plugin_tv *tv) {
138 // We're given a pointer to the first transfer vector. We read through them
139 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
140 // contain pointers to functions that we need to call to register our own
141 // hooks. The others are addresses of functions we can use to call into gold
144 bool registeredClaimFile = false;
146 for (; tv->tv_tag != LDPT_NULL; ++tv) {
147 switch (tv->tv_tag) {
148 case LDPT_API_VERSION:
149 api_version = tv->tv_u.tv_val;
151 case LDPT_GOLD_VERSION: // major * 100 + minor
152 gold_version = tv->tv_u.tv_val;
154 case LDPT_OUTPUT_NAME:
155 output_name = tv->tv_u.tv_string;
157 case LDPT_LINKER_OUTPUT:
158 switch (tv->tv_u.tv_val) {
160 case LDPO_DYN: // .so
161 case LDPO_PIE: // position independent executable
162 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
164 case LDPO_EXEC: // .exe
165 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
168 (*message)(LDPL_ERROR, "Unknown output file type %d",
174 options::process_plugin_option(tv->tv_u.tv_string);
176 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
177 ld_plugin_register_claim_file callback;
178 callback = tv->tv_u.tv_register_claim_file;
180 if ((*callback)(claim_file_hook) != LDPS_OK)
183 registeredClaimFile = true;
185 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
186 ld_plugin_register_all_symbols_read callback;
187 callback = tv->tv_u.tv_register_all_symbols_read;
189 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
192 code_gen = lto_codegen_create();
194 case LDPT_REGISTER_CLEANUP_HOOK: {
195 ld_plugin_register_cleanup callback;
196 callback = tv->tv_u.tv_register_cleanup;
198 if ((*callback)(cleanup_hook) != LDPS_OK)
201 case LDPT_ADD_SYMBOLS:
202 add_symbols = tv->tv_u.tv_add_symbols;
204 case LDPT_GET_SYMBOLS_V2:
205 get_symbols = tv->tv_u.tv_get_symbols;
207 case LDPT_ADD_INPUT_FILE:
208 add_input_file = tv->tv_u.tv_add_input_file;
210 case LDPT_ADD_INPUT_LIBRARY:
211 add_input_library = tv->tv_u.tv_add_input_file;
213 case LDPT_SET_EXTRA_LIBRARY_PATH:
214 set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
217 get_view = tv->tv_u.tv_get_view;
220 message = tv->tv_u.tv_message;
227 if (!registeredClaimFile) {
228 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
232 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
239 /// claim_file_hook - called by gold to see whether this file is one that
240 /// our plugin can handle. We'll try to open it and register all the symbols
241 /// with add_symbol if possible.
242 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
246 std::unique_ptr<MemoryBuffer> buffer;
248 if (get_view(file->handle, &view) != LDPS_OK) {
249 (*message)(LDPL_ERROR, "Failed to get a view of %s", file->name);
254 // Gold has found what might be IR part-way inside of a file, such as
257 offset = file->offset;
259 if (std::error_code ec = MemoryBuffer::getOpenFileSlice(
260 file->fd, file->name, buffer, file->filesize, offset)) {
261 (*message)(LDPL_ERROR, ec.message().c_str());
264 view = buffer->getBufferStart();
267 if (!lto_module_is_object_file_in_memory(view, file->filesize))
270 M = lto_module_create_from_memory(view, file->filesize);
272 if (const char* msg = lto_get_error_message()) {
273 (*message)(LDPL_ERROR,
274 "LLVM gold plugin has failed to create LTO module: %s",
282 Modules.resize(Modules.size() + 1);
283 claimed_file &cf = Modules.back();
285 if (!options::triple.empty())
286 lto_module_set_target_triple(M, options::triple.c_str());
288 cf.handle = file->handle;
289 unsigned sym_count = lto_module_get_num_symbols(M);
290 cf.syms.reserve(sym_count);
292 for (unsigned i = 0; i != sym_count; ++i) {
293 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(M, i);
294 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
297 cf.syms.push_back(ld_plugin_symbol());
298 ld_plugin_symbol &sym = cf.syms.back();
299 sym.name = const_cast<char *>(lto_module_get_symbol_name(M, i));
300 sym.name = strdup(sym.name);
303 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
304 bool CanBeHidden = scope == LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN;
306 CannotBeHidden.insert(sym.name);
308 case LTO_SYMBOL_SCOPE_HIDDEN:
309 sym.visibility = LDPV_HIDDEN;
311 case LTO_SYMBOL_SCOPE_PROTECTED:
312 sym.visibility = LDPV_PROTECTED;
315 case LTO_SYMBOL_SCOPE_DEFAULT:
316 case LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN:
317 sym.visibility = LDPV_DEFAULT;
320 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
324 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
325 sym.comdat_key = NULL;
326 switch (definition) {
327 case LTO_SYMBOL_DEFINITION_REGULAR:
330 case LTO_SYMBOL_DEFINITION_UNDEFINED:
331 sym.def = LDPK_UNDEF;
333 case LTO_SYMBOL_DEFINITION_TENTATIVE:
334 sym.def = LDPK_COMMON;
336 case LTO_SYMBOL_DEFINITION_WEAK:
337 sym.comdat_key = sym.name;
338 sym.def = LDPK_WEAKDEF;
340 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
341 sym.def = LDPK_WEAKUNDEF;
344 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
350 sym.resolution = LDPR_UNKNOWN;
353 cf.syms.reserve(cf.syms.size());
355 if (!cf.syms.empty()) {
356 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
357 (*message)(LDPL_ERROR, "Unable to add symbols!");
363 if (lto_codegen_add_module(code_gen, M)) {
364 (*message)(LDPL_ERROR, "Error linking module: %s",
365 lto_get_error_message());
370 lto_module_dispose(M);
375 static bool mustPreserve(const claimed_file &F, int i) {
376 if (F.syms[i].resolution == LDPR_PREVAILING_DEF)
378 if (F.syms[i].resolution == LDPR_PREVAILING_DEF_IRONLY_EXP)
379 return CannotBeHidden.count(F.syms[i].name);
383 /// all_symbols_read_hook - gold informs us that all symbols have been read.
384 /// At this point, we use get_symbols to see if any of our definitions have
385 /// been overridden by a native object file. Then, perform optimization and
387 static ld_plugin_status all_symbols_read_hook(void) {
388 std::ofstream api_file;
391 if (options::generate_api_file) {
392 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
393 if (!api_file.is_open()) {
394 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
399 for (std::list<claimed_file>::iterator I = Modules.begin(),
400 E = Modules.end(); I != E; ++I) {
403 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
404 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
405 if (mustPreserve(*I, i)) {
406 lto_codegen_add_must_preserve_symbol(code_gen, I->syms[i].name);
408 if (options::generate_api_file)
409 api_file << I->syms[i].name << "\n";
414 if (options::generate_api_file)
417 lto_codegen_set_pic_model(code_gen, output_type);
418 lto_codegen_set_debug_model(code_gen, LTO_DEBUG_MODEL_DWARF);
419 if (!options::mcpu.empty())
420 lto_codegen_set_cpu(code_gen, 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(code_gen, (*it).c_str());
430 if (options::generate_bc_file != options::BC_NO) {
432 if (options::generate_bc_file == options::BC_ONLY)
434 else if (!options::bc_path.empty())
435 path = options::bc_path;
437 path = output_name + ".bc";
438 bool err = lto_codegen_write_merged_modules(code_gen, path.c_str());
440 (*message)(LDPL_FATAL, "Failed to write the output file.");
441 if (options::generate_bc_file == options::BC_ONLY) {
442 lto_codegen_dispose(code_gen);
450 if (lto_codegen_compile_to_file(code_gen, &Temp)) {
451 (*message)(LDPL_ERROR, "Could not produce a combined object file\n");
456 lto_codegen_dispose(code_gen);
457 for (std::list<claimed_file>::iterator I = Modules.begin(),
458 E = Modules.end(); I != E; ++I) {
459 for (unsigned i = 0; i != I->syms.size(); ++i) {
460 ld_plugin_symbol &sym = I->syms[i];
465 if ((*add_input_file)(ObjPath.c_str()) != LDPS_OK) {
466 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
467 (*message)(LDPL_ERROR, "File left behind in: %s", ObjPath.c_str());
471 if (!options::extra_library_path.empty() &&
472 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) {
473 (*message)(LDPL_ERROR, "Unable to set the extra library path.");
477 if (options::obj_path.empty())
478 Cleanup.push_back(ObjPath);
483 static ld_plugin_status cleanup_hook(void) {
484 for (int i = 0, e = Cleanup.size(); i != e; ++i) {
485 std::error_code EC = sys::fs::remove(Cleanup[i]);
487 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),
488 EC.message().c_str());