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 <plugin-api.h>
17 #include "llvm-c/lto.h"
18 #include "llvm/ADT/StringSet.h"
19 #include "llvm/ADT/OwningPtr.h"
20 #include "llvm/Support/Errno.h"
21 #include "llvm/Support/FileSystem.h"
22 #include "llvm/Support/MemoryBuffer.h"
23 #include "llvm/Support/Path.h"
24 #include "llvm/Support/Program.h"
25 #include "llvm/Support/ToolOutputFile.h"
26 #include "llvm/Support/system_error.h"
34 // Support Windows/MinGW crazyness.
44 ld_plugin_status discard_message(int level, const char *format, ...) {
45 // Die loudly. Recent versions of Gold pass ld_plugin_message as the first
46 // callback in the transfer vector. This should never be called.
50 ld_plugin_add_symbols add_symbols = NULL;
51 ld_plugin_get_symbols get_symbols = NULL;
52 ld_plugin_add_input_file add_input_file = NULL;
53 ld_plugin_add_input_library add_input_library = NULL;
54 ld_plugin_set_extra_library_path set_extra_library_path = NULL;
55 ld_plugin_get_view get_view = NULL;
56 ld_plugin_message message = discard_message;
63 std::vector<ld_plugin_symbol> syms;
66 lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
67 std::string output_name = "";
68 std::list<claimed_file> Modules;
69 std::vector<std::string> Cleanup;
70 lto_code_gen_t code_gen = NULL;
71 StringSet<> CannotBeHidden;
75 enum generate_bc { BC_NO, BC_ALSO, BC_ONLY };
76 static bool generate_api_file = false;
77 static generate_bc generate_bc_file = BC_NO;
78 static std::string bc_path;
79 static std::string obj_path;
80 static std::string extra_library_path;
81 static std::string triple;
82 static std::string mcpu;
83 // Additional options to pass into the code generator.
84 // Note: This array will contain all plugin options which are not claimed
85 // as plugin exclusive to pass to the code generator.
86 // For example, "generate-api-file" and "as"options are for the plugin
87 // use only and will not be passed.
88 static std::vector<std::string> extra;
90 static void process_plugin_option(const char* opt_)
94 llvm::StringRef opt = opt_;
96 if (opt == "generate-api-file") {
97 generate_api_file = true;
98 } else if (opt.startswith("mcpu=")) {
99 mcpu = opt.substr(strlen("mcpu="));
100 } else if (opt.startswith("extra-library-path=")) {
101 extra_library_path = opt.substr(strlen("extra_library_path="));
102 } else if (opt.startswith("mtriple=")) {
103 triple = opt.substr(strlen("mtriple="));
104 } else if (opt.startswith("obj-path=")) {
105 obj_path = opt.substr(strlen("obj-path="));
106 } else if (opt == "emit-llvm") {
107 generate_bc_file = BC_ONLY;
108 } else if (opt == "also-emit-llvm") {
109 generate_bc_file = BC_ALSO;
110 } else if (opt.startswith("also-emit-llvm=")) {
111 llvm::StringRef path = opt.substr(strlen("also-emit-llvm="));
112 generate_bc_file = BC_ALSO;
113 if (!bc_path.empty()) {
114 (*message)(LDPL_WARNING, "Path to the output IL file specified twice. "
115 "Discarding %s", opt_);
120 // Save this option to pass to the code generator.
121 extra.push_back(opt);
126 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
128 static ld_plugin_status all_symbols_read_hook(void);
129 static ld_plugin_status cleanup_hook(void);
131 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
132 ld_plugin_status onload(ld_plugin_tv *tv) {
133 // We're given a pointer to the first transfer vector. We read through them
134 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
135 // contain pointers to functions that we need to call to register our own
136 // hooks. The others are addresses of functions we can use to call into gold
139 bool registeredClaimFile = false;
141 for (; tv->tv_tag != LDPT_NULL; ++tv) {
142 switch (tv->tv_tag) {
143 case LDPT_API_VERSION:
144 api_version = tv->tv_u.tv_val;
146 case LDPT_GOLD_VERSION: // major * 100 + minor
147 gold_version = tv->tv_u.tv_val;
149 case LDPT_OUTPUT_NAME:
150 output_name = tv->tv_u.tv_string;
152 case LDPT_LINKER_OUTPUT:
153 switch (tv->tv_u.tv_val) {
155 case LDPO_DYN: // .so
156 // FIXME: Replace 3 with LDPO_PIE once that is in a released binutils.
157 case 3: // position independent executable
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 code_gen = lto_codegen_create();
192 case LDPT_REGISTER_CLEANUP_HOOK: {
193 ld_plugin_register_cleanup callback;
194 callback = tv->tv_u.tv_register_cleanup;
196 if ((*callback)(cleanup_hook) != LDPS_OK)
199 case LDPT_ADD_SYMBOLS:
200 add_symbols = tv->tv_u.tv_add_symbols;
202 case LDPT_GET_SYMBOLS_V2:
203 get_symbols = tv->tv_u.tv_get_symbols;
205 case LDPT_ADD_INPUT_FILE:
206 add_input_file = tv->tv_u.tv_add_input_file;
208 case LDPT_ADD_INPUT_LIBRARY:
209 add_input_library = tv->tv_u.tv_add_input_file;
211 case LDPT_SET_EXTRA_LIBRARY_PATH:
212 set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
215 get_view = tv->tv_u.tv_get_view;
218 message = tv->tv_u.tv_message;
225 if (!registeredClaimFile) {
226 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
230 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
237 /// claim_file_hook - called by gold to see whether this file is one that
238 /// our plugin can handle. We'll try to open it and register all the symbols
239 /// with add_symbol if possible.
240 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
244 OwningPtr<MemoryBuffer> buffer;
246 if (get_view(file->handle, &view) != LDPS_OK) {
247 (*message)(LDPL_ERROR, "Failed to get a view of %s", file->name);
252 // Gold has found what might be IR part-way inside of a file, such as
255 offset = file->offset;
257 if (error_code ec = MemoryBuffer::getOpenFileSlice(
258 file->fd, file->name, buffer, file->filesize, offset)) {
259 (*message)(LDPL_ERROR, ec.message().c_str());
262 view = buffer->getBufferStart();
265 if (!lto_module_is_object_file_in_memory(view, file->filesize))
268 M = lto_module_create_from_memory(view, file->filesize);
270 if (const char* msg = lto_get_error_message()) {
271 (*message)(LDPL_ERROR,
272 "LLVM gold plugin has failed to create LTO module: %s",
280 Modules.resize(Modules.size() + 1);
281 claimed_file &cf = Modules.back();
283 if (!options::triple.empty())
284 lto_module_set_target_triple(M, options::triple.c_str());
286 cf.handle = file->handle;
287 unsigned sym_count = lto_module_get_num_symbols(M);
288 cf.syms.reserve(sym_count);
290 for (unsigned i = 0; i != sym_count; ++i) {
291 lto_symbol_attributes attrs = lto_module_get_symbol_attribute(M, i);
292 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
295 cf.syms.push_back(ld_plugin_symbol());
296 ld_plugin_symbol &sym = cf.syms.back();
297 sym.name = const_cast<char *>(lto_module_get_symbol_name(M, i));
298 sym.name = strdup(sym.name);
301 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
302 bool CanBeHidden = scope == LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN;
304 CannotBeHidden.insert(sym.name);
306 case LTO_SYMBOL_SCOPE_HIDDEN:
307 sym.visibility = LDPV_HIDDEN;
309 case LTO_SYMBOL_SCOPE_PROTECTED:
310 sym.visibility = LDPV_PROTECTED;
313 case LTO_SYMBOL_SCOPE_DEFAULT:
314 case LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN:
315 sym.visibility = LDPV_DEFAULT;
318 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
322 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
323 sym.comdat_key = NULL;
324 switch (definition) {
325 case LTO_SYMBOL_DEFINITION_REGULAR:
328 case LTO_SYMBOL_DEFINITION_UNDEFINED:
329 sym.def = LDPK_UNDEF;
331 case LTO_SYMBOL_DEFINITION_TENTATIVE:
332 sym.def = LDPK_COMMON;
334 case LTO_SYMBOL_DEFINITION_WEAK:
335 sym.comdat_key = sym.name;
336 sym.def = LDPK_WEAKDEF;
338 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
339 sym.def = LDPK_WEAKUNDEF;
342 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
348 sym.resolution = LDPR_UNKNOWN;
351 cf.syms.reserve(cf.syms.size());
353 if (!cf.syms.empty()) {
354 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
355 (*message)(LDPL_ERROR, "Unable to add symbols!");
361 if (lto_codegen_add_module(code_gen, M)) {
362 (*message)(LDPL_ERROR, "Error linking module: %s",
363 lto_get_error_message());
368 lto_module_dispose(M);
373 static bool mustPreserve(const claimed_file &F, int i) {
374 if (F.syms[i].resolution == LDPR_PREVAILING_DEF)
376 if (F.syms[i].resolution == LDPR_PREVAILING_DEF_IRONLY_EXP)
377 return CannotBeHidden.count(F.syms[i].name);
381 /// all_symbols_read_hook - gold informs us that all symbols have been read.
382 /// At this point, we use get_symbols to see if any of our definitions have
383 /// been overridden by a native object file. Then, perform optimization and
385 static ld_plugin_status all_symbols_read_hook(void) {
386 std::ofstream api_file;
389 if (options::generate_api_file) {
390 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
391 if (!api_file.is_open()) {
392 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
397 for (std::list<claimed_file>::iterator I = Modules.begin(),
398 E = Modules.end(); I != E; ++I) {
401 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
402 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
403 if (mustPreserve(*I, i)) {
404 lto_codegen_add_must_preserve_symbol(code_gen, I->syms[i].name);
406 if (options::generate_api_file)
407 api_file << I->syms[i].name << "\n";
412 if (options::generate_api_file)
415 lto_codegen_set_pic_model(code_gen, output_type);
416 lto_codegen_set_debug_model(code_gen, LTO_DEBUG_MODEL_DWARF);
417 if (!options::mcpu.empty())
418 lto_codegen_set_cpu(code_gen, options::mcpu.c_str());
420 // Pass through extra options to the code generator.
421 if (!options::extra.empty()) {
422 for (std::vector<std::string>::iterator it = options::extra.begin();
423 it != options::extra.end(); ++it) {
424 lto_codegen_debug_options(code_gen, (*it).c_str());
428 if (options::generate_bc_file != options::BC_NO) {
430 if (options::generate_bc_file == options::BC_ONLY)
432 else if (!options::bc_path.empty())
433 path = options::bc_path;
435 path = output_name + ".bc";
436 bool err = lto_codegen_write_merged_modules(code_gen, path.c_str());
438 (*message)(LDPL_FATAL, "Failed to write the output file.");
439 if (options::generate_bc_file == options::BC_ONLY) {
440 lto_codegen_dispose(code_gen);
448 if (lto_codegen_compile_to_file(code_gen, &Temp)) {
449 (*message)(LDPL_ERROR, "Could not produce a combined object file\n");
454 lto_codegen_dispose(code_gen);
455 for (std::list<claimed_file>::iterator I = Modules.begin(),
456 E = Modules.end(); I != E; ++I) {
457 for (unsigned i = 0; i != I->syms.size(); ++i) {
458 ld_plugin_symbol &sym = I->syms[i];
463 if ((*add_input_file)(ObjPath.c_str()) != LDPS_OK) {
464 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
465 (*message)(LDPL_ERROR, "File left behind in: %s", ObjPath.c_str());
469 if (!options::extra_library_path.empty() &&
470 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) {
471 (*message)(LDPL_ERROR, "Unable to set the extra library path.");
475 if (options::obj_path.empty())
476 Cleanup.push_back(ObjPath);
481 static ld_plugin_status cleanup_hook(void) {
482 for (int i = 0, e = Cleanup.size(); i != e; ++i) {
483 error_code EC = sys::fs::remove(Cleanup[i]);
485 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),
486 EC.message().c_str());