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/CodeGen/CommandFlags.h"
19 #include "llvm/LTO/LTOCodeGenerator.h"
20 #include "llvm/LTO/LTOModule.h"
21 #include "llvm/Support/Errno.h"
22 #include "llvm/Support/FileSystem.h"
23 #include "llvm/Support/MemoryBuffer.h"
24 #include "llvm/Support/Path.h"
25 #include "llvm/Support/Program.h"
26 #include "llvm/Support/TargetSelect.h"
27 #include "llvm/Support/ToolOutputFile.h"
33 #include <plugin-api.h>
34 #include <system_error>
37 // Support Windows/MinGW crazyness.
45 // FIXME: remove this declaration when we stop maintaining Ubuntu Quantal and
46 // Precise and Debian Wheezy (binutils 2.23 is required)
55 std::vector<ld_plugin_symbol> syms;
59 static ld_plugin_status discard_message(int level, const char *format, ...) {
60 // Die loudly. Recent versions of Gold pass ld_plugin_message as the first
61 // callback in the transfer vector. This should never be called.
65 static ld_plugin_add_symbols add_symbols = NULL;
66 static ld_plugin_get_symbols get_symbols = NULL;
67 static ld_plugin_add_input_file add_input_file = NULL;
68 static ld_plugin_set_extra_library_path set_extra_library_path = NULL;
69 static ld_plugin_get_view get_view = NULL;
70 static ld_plugin_message message = discard_message;
71 static lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
72 static std::string output_name = "";
73 static std::list<claimed_file> Modules;
74 static std::vector<std::string> Cleanup;
75 static LTOCodeGenerator *CodeGen = nullptr;
76 static StringSet<> CannotBeHidden;
77 static llvm::TargetOptions TargetOpts;
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;
145 bool RegisteredAllSymbolsRead = false;
147 for (; tv->tv_tag != LDPT_NULL; ++tv) {
148 switch (tv->tv_tag) {
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 case LDPO_PIE: // position independent executable
157 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
159 case LDPO_EXEC: // .exe
160 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
163 (*message)(LDPL_ERROR, "Unknown output file type %d",
169 options::process_plugin_option(tv->tv_u.tv_string);
171 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
172 ld_plugin_register_claim_file callback;
173 callback = tv->tv_u.tv_register_claim_file;
175 if ((*callback)(claim_file_hook) != LDPS_OK)
178 registeredClaimFile = true;
180 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
181 ld_plugin_register_all_symbols_read callback;
182 callback = tv->tv_u.tv_register_all_symbols_read;
184 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
187 RegisteredAllSymbolsRead = true;
189 case LDPT_REGISTER_CLEANUP_HOOK: {
190 ld_plugin_register_cleanup callback;
191 callback = tv->tv_u.tv_register_cleanup;
193 if ((*callback)(cleanup_hook) != LDPS_OK)
196 case LDPT_ADD_SYMBOLS:
197 add_symbols = tv->tv_u.tv_add_symbols;
199 case LDPT_GET_SYMBOLS_V2:
200 get_symbols = tv->tv_u.tv_get_symbols;
202 case LDPT_ADD_INPUT_FILE:
203 add_input_file = tv->tv_u.tv_add_input_file;
205 case LDPT_SET_EXTRA_LIBRARY_PATH:
206 set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
209 get_view = tv->tv_u.tv_get_view;
212 message = tv->tv_u.tv_message;
219 if (!registeredClaimFile) {
220 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
224 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
228 if (!RegisteredAllSymbolsRead)
231 InitializeAllTargetInfos();
232 InitializeAllTargets();
233 InitializeAllTargetMCs();
234 InitializeAllAsmParsers();
235 InitializeAllAsmPrinters();
236 CodeGen = new LTOCodeGenerator();
238 // Pass through extra options to the code generator.
239 if (!options::extra.empty()) {
240 for (std::vector<std::string>::iterator it = options::extra.begin();
241 it != options::extra.end(); ++it) {
242 CodeGen->setCodeGenDebugOptions((*it).c_str());
246 CodeGen->parseCodeGenDebugOptions();
249 for (unsigned I = 0; I < MAttrs.size(); ++I) {
252 Attrs.append(MAttrs[I]);
254 CodeGen->setAttr(Attrs.c_str());
257 TargetOpts = InitTargetOptionsFromCodeGenFlags();
258 CodeGen->setTargetOptions(TargetOpts);
263 /// claim_file_hook - called by gold to see whether this file is one that
264 /// our plugin can handle. We'll try to open it and register all the symbols
265 /// with add_symbol if possible.
266 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
270 std::unique_ptr<MemoryBuffer> buffer;
272 if (get_view(file->handle, &view) != LDPS_OK) {
273 (*message)(LDPL_ERROR, "Failed to get a view of %s", file->name);
278 // Gold has found what might be IR part-way inside of a file, such as
281 offset = file->offset;
283 if (std::error_code ec = MemoryBuffer::getOpenFileSlice(
284 file->fd, file->name, buffer, file->filesize, offset)) {
285 (*message)(LDPL_ERROR, ec.message().c_str());
288 view = buffer->getBufferStart();
291 if (!LTOModule::isBitcodeFile(view, file->filesize))
295 M = LTOModule::createFromBuffer(view, file->filesize, TargetOpts, Error);
297 (*message)(LDPL_ERROR,
298 "LLVM gold plugin has failed to create LTO module: %s",
304 Modules.resize(Modules.size() + 1);
305 claimed_file &cf = Modules.back();
307 if (!options::triple.empty())
308 M->setTargetTriple(options::triple.c_str());
310 cf.handle = file->handle;
311 unsigned sym_count = M->getSymbolCount();
312 cf.syms.reserve(sym_count);
314 for (unsigned i = 0; i != sym_count; ++i) {
315 lto_symbol_attributes attrs = M->getSymbolAttributes(i);
316 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
319 cf.syms.push_back(ld_plugin_symbol());
320 ld_plugin_symbol &sym = cf.syms.back();
321 sym.name = strdup(M->getSymbolName(i));
324 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
325 bool CanBeHidden = scope == LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN;
327 CannotBeHidden.insert(sym.name);
329 case LTO_SYMBOL_SCOPE_HIDDEN:
330 sym.visibility = LDPV_HIDDEN;
332 case LTO_SYMBOL_SCOPE_PROTECTED:
333 sym.visibility = LDPV_PROTECTED;
336 case LTO_SYMBOL_SCOPE_DEFAULT:
337 case LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN:
338 sym.visibility = LDPV_DEFAULT;
341 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
345 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
346 sym.comdat_key = NULL;
347 switch (definition) {
348 case LTO_SYMBOL_DEFINITION_REGULAR:
351 case LTO_SYMBOL_DEFINITION_UNDEFINED:
352 sym.def = LDPK_UNDEF;
354 case LTO_SYMBOL_DEFINITION_TENTATIVE:
355 sym.def = LDPK_COMMON;
357 case LTO_SYMBOL_DEFINITION_WEAK:
358 sym.comdat_key = sym.name;
359 sym.def = LDPK_WEAKDEF;
361 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
362 sym.def = LDPK_WEAKUNDEF;
365 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
371 sym.resolution = LDPR_UNKNOWN;
374 cf.syms.reserve(cf.syms.size());
376 if (!cf.syms.empty()) {
377 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
378 (*message)(LDPL_ERROR, "Unable to add symbols!");
385 if (!CodeGen->addModule(M, Error)) {
386 (*message)(LDPL_ERROR, "Error linking module: %s", Error.c_str());
396 static bool mustPreserve(const claimed_file &F, int i) {
397 if (F.syms[i].resolution == LDPR_PREVAILING_DEF)
399 if (F.syms[i].resolution == LDPR_PREVAILING_DEF_IRONLY_EXP)
400 return CannotBeHidden.count(F.syms[i].name);
404 /// all_symbols_read_hook - gold informs us that all symbols have been read.
405 /// At this point, we use get_symbols to see if any of our definitions have
406 /// been overridden by a native object file. Then, perform optimization and
408 static ld_plugin_status all_symbols_read_hook(void) {
409 std::ofstream api_file;
412 if (options::generate_api_file) {
413 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
414 if (!api_file.is_open()) {
415 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
420 for (std::list<claimed_file>::iterator I = Modules.begin(),
421 E = Modules.end(); I != E; ++I) {
424 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
425 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
426 if (mustPreserve(*I, i)) {
427 CodeGen->addMustPreserveSymbol(I->syms[i].name);
429 if (options::generate_api_file)
430 api_file << I->syms[i].name << "\n";
435 if (options::generate_api_file)
438 CodeGen->setCodePICModel(output_type);
439 CodeGen->setDebugInfo(LTO_DEBUG_MODEL_DWARF);
440 if (!options::mcpu.empty())
441 CodeGen->setCpu(options::mcpu.c_str());
443 if (options::generate_bc_file != options::BC_NO) {
445 if (options::generate_bc_file == options::BC_ONLY)
447 else if (!options::bc_path.empty())
448 path = options::bc_path;
450 path = output_name + ".bc";
452 if (!CodeGen->writeMergedModules(path.c_str(), Error))
453 (*message)(LDPL_FATAL, "Failed to write the output file.");
454 if (options::generate_bc_file == options::BC_ONLY) {
464 if (!CodeGen->compile_to_file(&Temp, /*DisableOpt*/ false, /*DisableInline*/
465 false, /*DisableGVNLoadPRE*/ false, Error))
466 (*message)(LDPL_ERROR, "Could not produce a combined object file\n");
471 for (std::list<claimed_file>::iterator I = Modules.begin(),
472 E = Modules.end(); I != E; ++I) {
473 for (unsigned i = 0; i != I->syms.size(); ++i) {
474 ld_plugin_symbol &sym = I->syms[i];
479 if ((*add_input_file)(ObjPath.c_str()) != LDPS_OK) {
480 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
481 (*message)(LDPL_ERROR, "File left behind in: %s", ObjPath.c_str());
485 if (!options::extra_library_path.empty() &&
486 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) {
487 (*message)(LDPL_ERROR, "Unable to set the extra library path.");
491 if (options::obj_path.empty())
492 Cleanup.push_back(ObjPath);
497 static ld_plugin_status cleanup_hook(void) {
498 for (int i = 0, e = Cleanup.size(); i != e; ++i) {
499 std::error_code EC = sys::fs::remove(Cleanup[i]);
501 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),
502 EC.message().c_str());