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)
53 ld_plugin_status discard_message(int level, const char *format, ...) {
54 // Die loudly. Recent versions of Gold pass ld_plugin_message as the first
55 // callback in the transfer vector. This should never be called.
59 ld_plugin_add_symbols add_symbols = NULL;
60 ld_plugin_get_symbols get_symbols = NULL;
61 ld_plugin_add_input_file add_input_file = NULL;
62 ld_plugin_add_input_library add_input_library = NULL;
63 ld_plugin_set_extra_library_path set_extra_library_path = NULL;
64 ld_plugin_get_view get_view = NULL;
65 ld_plugin_message message = discard_message;
72 std::vector<ld_plugin_symbol> syms;
75 lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
76 std::string output_name = "";
77 std::list<claimed_file> Modules;
78 std::vector<std::string> Cleanup;
79 LTOCodeGenerator *CodeGen = nullptr;
80 StringSet<> CannotBeHidden;
82 static llvm::TargetOptions TargetOpts;
85 enum generate_bc { BC_NO, BC_ALSO, BC_ONLY };
86 static bool generate_api_file = false;
87 static generate_bc generate_bc_file = BC_NO;
88 static std::string bc_path;
89 static std::string obj_path;
90 static std::string extra_library_path;
91 static std::string triple;
92 static std::string mcpu;
93 // Additional options to pass into the code generator.
94 // Note: This array will contain all plugin options which are not claimed
95 // as plugin exclusive to pass to the code generator.
96 // For example, "generate-api-file" and "as"options are for the plugin
97 // use only and will not be passed.
98 static std::vector<std::string> extra;
100 static void process_plugin_option(const char* opt_)
104 llvm::StringRef opt = opt_;
106 if (opt == "generate-api-file") {
107 generate_api_file = true;
108 } else if (opt.startswith("mcpu=")) {
109 mcpu = opt.substr(strlen("mcpu="));
110 } else if (opt.startswith("extra-library-path=")) {
111 extra_library_path = opt.substr(strlen("extra_library_path="));
112 } else if (opt.startswith("mtriple=")) {
113 triple = opt.substr(strlen("mtriple="));
114 } else if (opt.startswith("obj-path=")) {
115 obj_path = opt.substr(strlen("obj-path="));
116 } else if (opt == "emit-llvm") {
117 generate_bc_file = BC_ONLY;
118 } else if (opt == "also-emit-llvm") {
119 generate_bc_file = BC_ALSO;
120 } else if (opt.startswith("also-emit-llvm=")) {
121 llvm::StringRef path = opt.substr(strlen("also-emit-llvm="));
122 generate_bc_file = BC_ALSO;
123 if (!bc_path.empty()) {
124 (*message)(LDPL_WARNING, "Path to the output IL file specified twice. "
125 "Discarding %s", opt_);
130 // Save this option to pass to the code generator.
131 extra.push_back(opt);
136 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
138 static ld_plugin_status all_symbols_read_hook(void);
139 static ld_plugin_status cleanup_hook(void);
141 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
142 ld_plugin_status onload(ld_plugin_tv *tv) {
143 // We're given a pointer to the first transfer vector. We read through them
144 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
145 // contain pointers to functions that we need to call to register our own
146 // hooks. The others are addresses of functions we can use to call into gold
149 bool registeredClaimFile = false;
150 bool RegisteredAllSymbolsRead = false;
152 for (; tv->tv_tag != LDPT_NULL; ++tv) {
153 switch (tv->tv_tag) {
154 case LDPT_API_VERSION:
155 api_version = tv->tv_u.tv_val;
157 case LDPT_GOLD_VERSION: // major * 100 + minor
158 gold_version = tv->tv_u.tv_val;
160 case LDPT_OUTPUT_NAME:
161 output_name = tv->tv_u.tv_string;
163 case LDPT_LINKER_OUTPUT:
164 switch (tv->tv_u.tv_val) {
166 case LDPO_DYN: // .so
167 case LDPO_PIE: // position independent executable
168 output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
170 case LDPO_EXEC: // .exe
171 output_type = LTO_CODEGEN_PIC_MODEL_STATIC;
174 (*message)(LDPL_ERROR, "Unknown output file type %d",
180 options::process_plugin_option(tv->tv_u.tv_string);
182 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
183 ld_plugin_register_claim_file callback;
184 callback = tv->tv_u.tv_register_claim_file;
186 if ((*callback)(claim_file_hook) != LDPS_OK)
189 registeredClaimFile = true;
191 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
192 ld_plugin_register_all_symbols_read callback;
193 callback = tv->tv_u.tv_register_all_symbols_read;
195 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
198 RegisteredAllSymbolsRead = true;
200 case LDPT_REGISTER_CLEANUP_HOOK: {
201 ld_plugin_register_cleanup callback;
202 callback = tv->tv_u.tv_register_cleanup;
204 if ((*callback)(cleanup_hook) != LDPS_OK)
207 case LDPT_ADD_SYMBOLS:
208 add_symbols = tv->tv_u.tv_add_symbols;
210 case LDPT_GET_SYMBOLS_V2:
211 get_symbols = tv->tv_u.tv_get_symbols;
213 case LDPT_ADD_INPUT_FILE:
214 add_input_file = tv->tv_u.tv_add_input_file;
216 case LDPT_ADD_INPUT_LIBRARY:
217 add_input_library = tv->tv_u.tv_add_input_file;
219 case LDPT_SET_EXTRA_LIBRARY_PATH:
220 set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
223 get_view = tv->tv_u.tv_get_view;
226 message = tv->tv_u.tv_message;
233 if (!registeredClaimFile) {
234 (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
238 (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
242 if (!RegisteredAllSymbolsRead)
245 InitializeAllTargetInfos();
246 InitializeAllTargets();
247 InitializeAllTargetMCs();
248 InitializeAllAsmParsers();
249 InitializeAllAsmPrinters();
250 InitializeAllDisassemblers();
251 TargetOpts = InitTargetOptionsFromCodeGenFlags();
252 CodeGen = new LTOCodeGenerator();
253 CodeGen->setTargetOptions(TargetOpts);
256 for (unsigned I = 0; I < MAttrs.size(); ++I) {
259 Attrs.append(MAttrs[I]);
261 CodeGen->setAttr(Attrs.c_str());
267 /// claim_file_hook - called by gold to see whether this file is one that
268 /// our plugin can handle. We'll try to open it and register all the symbols
269 /// with add_symbol if possible.
270 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
274 std::unique_ptr<MemoryBuffer> buffer;
276 if (get_view(file->handle, &view) != LDPS_OK) {
277 (*message)(LDPL_ERROR, "Failed to get a view of %s", file->name);
282 // Gold has found what might be IR part-way inside of a file, such as
285 offset = file->offset;
287 if (std::error_code ec = MemoryBuffer::getOpenFileSlice(
288 file->fd, file->name, buffer, file->filesize, offset)) {
289 (*message)(LDPL_ERROR, ec.message().c_str());
292 view = buffer->getBufferStart();
295 if (!LTOModule::isBitcodeFile(view, file->filesize))
299 M = LTOModule::makeLTOModule(view, file->filesize, TargetOpts, Error);
301 (*message)(LDPL_ERROR,
302 "LLVM gold plugin has failed to create LTO module: %s",
308 Modules.resize(Modules.size() + 1);
309 claimed_file &cf = Modules.back();
311 if (!options::triple.empty())
312 M->setTargetTriple(options::triple.c_str());
314 cf.handle = file->handle;
315 unsigned sym_count = M->getSymbolCount();
316 cf.syms.reserve(sym_count);
318 for (unsigned i = 0; i != sym_count; ++i) {
319 lto_symbol_attributes attrs = M->getSymbolAttributes(i);
320 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
323 cf.syms.push_back(ld_plugin_symbol());
324 ld_plugin_symbol &sym = cf.syms.back();
325 sym.name = strdup(M->getSymbolName(i));
328 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
329 bool CanBeHidden = scope == LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN;
331 CannotBeHidden.insert(sym.name);
333 case LTO_SYMBOL_SCOPE_HIDDEN:
334 sym.visibility = LDPV_HIDDEN;
336 case LTO_SYMBOL_SCOPE_PROTECTED:
337 sym.visibility = LDPV_PROTECTED;
340 case LTO_SYMBOL_SCOPE_DEFAULT:
341 case LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN:
342 sym.visibility = LDPV_DEFAULT;
345 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
349 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
350 sym.comdat_key = NULL;
351 switch (definition) {
352 case LTO_SYMBOL_DEFINITION_REGULAR:
355 case LTO_SYMBOL_DEFINITION_UNDEFINED:
356 sym.def = LDPK_UNDEF;
358 case LTO_SYMBOL_DEFINITION_TENTATIVE:
359 sym.def = LDPK_COMMON;
361 case LTO_SYMBOL_DEFINITION_WEAK:
362 sym.comdat_key = sym.name;
363 sym.def = LDPK_WEAKDEF;
365 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
366 sym.def = LDPK_WEAKUNDEF;
369 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
375 sym.resolution = LDPR_UNKNOWN;
378 cf.syms.reserve(cf.syms.size());
380 if (!cf.syms.empty()) {
381 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
382 (*message)(LDPL_ERROR, "Unable to add symbols!");
389 if (!CodeGen->addModule(M, Error)) {
390 (*message)(LDPL_ERROR, "Error linking module: %s", Error.c_str());
400 static bool mustPreserve(const claimed_file &F, int i) {
401 if (F.syms[i].resolution == LDPR_PREVAILING_DEF)
403 if (F.syms[i].resolution == LDPR_PREVAILING_DEF_IRONLY_EXP)
404 return CannotBeHidden.count(F.syms[i].name);
408 /// all_symbols_read_hook - gold informs us that all symbols have been read.
409 /// At this point, we use get_symbols to see if any of our definitions have
410 /// been overridden by a native object file. Then, perform optimization and
412 static ld_plugin_status all_symbols_read_hook(void) {
413 std::ofstream api_file;
416 if (options::generate_api_file) {
417 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
418 if (!api_file.is_open()) {
419 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
424 for (std::list<claimed_file>::iterator I = Modules.begin(),
425 E = Modules.end(); I != E; ++I) {
428 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
429 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
430 if (mustPreserve(*I, i)) {
431 CodeGen->addMustPreserveSymbol(I->syms[i].name);
433 if (options::generate_api_file)
434 api_file << I->syms[i].name << "\n";
439 if (options::generate_api_file)
442 CodeGen->setCodePICModel(output_type);
443 CodeGen->setDebugInfo(LTO_DEBUG_MODEL_DWARF);
444 if (!options::mcpu.empty())
445 CodeGen->setCpu(options::mcpu.c_str());
447 // Pass through extra options to the code generator.
448 if (!options::extra.empty()) {
449 for (std::vector<std::string>::iterator it = options::extra.begin();
450 it != options::extra.end(); ++it) {
451 CodeGen->setCodeGenDebugOptions((*it).c_str());
455 if (options::generate_bc_file != options::BC_NO) {
457 if (options::generate_bc_file == options::BC_ONLY)
459 else if (!options::bc_path.empty())
460 path = options::bc_path;
462 path = output_name + ".bc";
463 CodeGen->parseCodeGenDebugOptions();
465 if (!CodeGen->writeMergedModules(path.c_str(), Error))
466 (*message)(LDPL_FATAL, "Failed to write the output file.");
467 if (options::generate_bc_file == options::BC_ONLY) {
476 CodeGen->parseCodeGenDebugOptions();
478 if (!CodeGen->compile_to_file(&Temp, /*DisableOpt*/ false, /*DisableInline*/
479 false, /*DisableGVNLoadPRE*/ false, Error))
480 (*message)(LDPL_ERROR, "Could not produce a combined object file\n");
485 for (std::list<claimed_file>::iterator I = Modules.begin(),
486 E = Modules.end(); I != E; ++I) {
487 for (unsigned i = 0; i != I->syms.size(); ++i) {
488 ld_plugin_symbol &sym = I->syms[i];
493 if ((*add_input_file)(ObjPath.c_str()) != LDPS_OK) {
494 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
495 (*message)(LDPL_ERROR, "File left behind in: %s", ObjPath.c_str());
499 if (!options::extra_library_path.empty() &&
500 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) {
501 (*message)(LDPL_ERROR, "Unable to set the extra library path.");
505 if (options::obj_path.empty())
506 Cleanup.push_back(ObjPath);
511 static ld_plugin_status cleanup_hook(void) {
512 for (int i = 0, e = Cleanup.size(); i != e; ++i) {
513 std::error_code EC = sys::fs::remove(Cleanup[i]);
515 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),
516 EC.message().c_str());