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 InitializeAllTargetInfos();
139 InitializeAllTargets();
140 InitializeAllTargetMCs();
141 InitializeAllAsmParsers();
142 InitializeAllAsmPrinters();
144 // We're given a pointer to the first transfer vector. We read through them
145 // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
146 // contain pointers to functions that we need to call to register our own
147 // hooks. The others are addresses of functions we can use to call into gold
150 bool registeredClaimFile = false;
151 bool RegisteredAllSymbolsRead = false;
153 for (; tv->tv_tag != LDPT_NULL; ++tv) {
154 switch (tv->tv_tag) {
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",
175 options::process_plugin_option(tv->tv_u.tv_string);
177 case LDPT_REGISTER_CLAIM_FILE_HOOK: {
178 ld_plugin_register_claim_file callback;
179 callback = tv->tv_u.tv_register_claim_file;
181 if ((*callback)(claim_file_hook) != LDPS_OK)
184 registeredClaimFile = true;
186 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
187 ld_plugin_register_all_symbols_read callback;
188 callback = tv->tv_u.tv_register_all_symbols_read;
190 if ((*callback)(all_symbols_read_hook) != LDPS_OK)
193 RegisteredAllSymbolsRead = true;
195 case LDPT_REGISTER_CLEANUP_HOOK: {
196 ld_plugin_register_cleanup callback;
197 callback = tv->tv_u.tv_register_cleanup;
199 if ((*callback)(cleanup_hook) != LDPS_OK)
202 case LDPT_ADD_SYMBOLS:
203 add_symbols = tv->tv_u.tv_add_symbols;
205 case LDPT_GET_SYMBOLS_V2:
206 get_symbols = tv->tv_u.tv_get_symbols;
208 case LDPT_ADD_INPUT_FILE:
209 add_input_file = 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.");
234 if (!RegisteredAllSymbolsRead)
237 CodeGen = new LTOCodeGenerator();
239 // Pass through extra options to the code generator.
240 if (!options::extra.empty()) {
241 for (std::vector<std::string>::iterator it = options::extra.begin();
242 it != options::extra.end(); ++it) {
243 CodeGen->setCodeGenDebugOptions((*it).c_str());
247 CodeGen->parseCodeGenDebugOptions();
250 for (unsigned I = 0; I < MAttrs.size(); ++I) {
253 Attrs.append(MAttrs[I]);
255 CodeGen->setAttr(Attrs.c_str());
258 TargetOpts = InitTargetOptionsFromCodeGenFlags();
259 CodeGen->setTargetOptions(TargetOpts);
264 /// Called by gold to see whether this file is one that our plugin can handle.
265 /// We'll try to open it and register all the symbols with add_symbol if
267 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))
296 LTOModule::createFromBuffer(view, file->filesize, TargetOpts, Error);
298 (*message)(LDPL_ERROR,
299 "LLVM gold plugin has failed to create LTO module: %s",
305 Modules.resize(Modules.size() + 1);
306 claimed_file &cf = Modules.back();
308 if (!options::triple.empty())
309 M->setTargetTriple(options::triple.c_str());
311 cf.handle = file->handle;
312 unsigned sym_count = M->getSymbolCount();
313 cf.syms.reserve(sym_count);
315 for (unsigned i = 0; i != sym_count; ++i) {
316 lto_symbol_attributes attrs = M->getSymbolAttributes(i);
317 if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL)
320 cf.syms.push_back(ld_plugin_symbol());
321 ld_plugin_symbol &sym = cf.syms.back();
322 sym.name = strdup(M->getSymbolName(i));
325 int scope = attrs & LTO_SYMBOL_SCOPE_MASK;
326 bool CanBeHidden = scope == LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN;
328 CannotBeHidden.insert(sym.name);
330 case LTO_SYMBOL_SCOPE_HIDDEN:
331 sym.visibility = LDPV_HIDDEN;
333 case LTO_SYMBOL_SCOPE_PROTECTED:
334 sym.visibility = LDPV_PROTECTED;
337 case LTO_SYMBOL_SCOPE_DEFAULT:
338 case LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN:
339 sym.visibility = LDPV_DEFAULT;
342 (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope);
346 int definition = attrs & LTO_SYMBOL_DEFINITION_MASK;
347 sym.comdat_key = NULL;
348 switch (definition) {
349 case LTO_SYMBOL_DEFINITION_REGULAR:
352 case LTO_SYMBOL_DEFINITION_UNDEFINED:
353 sym.def = LDPK_UNDEF;
355 case LTO_SYMBOL_DEFINITION_TENTATIVE:
356 sym.def = LDPK_COMMON;
358 case LTO_SYMBOL_DEFINITION_WEAK:
359 sym.comdat_key = sym.name;
360 sym.def = LDPK_WEAKDEF;
362 case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
363 sym.def = LDPK_WEAKUNDEF;
366 (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition);
372 sym.resolution = LDPR_UNKNOWN;
375 cf.syms.reserve(cf.syms.size());
377 if (!cf.syms.empty()) {
378 if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
379 (*message)(LDPL_ERROR, "Unable to add symbols!");
386 if (!CodeGen->addModule(M, Error)) {
387 (*message)(LDPL_ERROR, "Error linking module: %s", Error.c_str());
397 static bool mustPreserve(const claimed_file &F, int i) {
398 if (F.syms[i].resolution == LDPR_PREVAILING_DEF)
400 if (F.syms[i].resolution == LDPR_PREVAILING_DEF_IRONLY_EXP)
401 return CannotBeHidden.count(F.syms[i].name);
405 /// all_symbols_read_hook - gold informs us that all symbols have been read.
406 /// At this point, we use get_symbols to see if any of our definitions have
407 /// been overridden by a native object file. Then, perform optimization and
409 static ld_plugin_status all_symbols_read_hook(void) {
410 std::ofstream api_file;
413 if (options::generate_api_file) {
414 api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc);
415 if (!api_file.is_open()) {
416 (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing.");
421 for (std::list<claimed_file>::iterator I = Modules.begin(),
422 E = Modules.end(); I != E; ++I) {
425 (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]);
426 for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
427 if (mustPreserve(*I, i)) {
428 CodeGen->addMustPreserveSymbol(I->syms[i].name);
430 if (options::generate_api_file)
431 api_file << I->syms[i].name << "\n";
436 if (options::generate_api_file)
439 CodeGen->setCodePICModel(output_type);
440 CodeGen->setDebugInfo(LTO_DEBUG_MODEL_DWARF);
441 if (!options::mcpu.empty())
442 CodeGen->setCpu(options::mcpu.c_str());
444 if (options::generate_bc_file != options::BC_NO) {
446 if (options::generate_bc_file == options::BC_ONLY)
448 else if (!options::bc_path.empty())
449 path = options::bc_path;
451 path = output_name + ".bc";
453 if (!CodeGen->writeMergedModules(path.c_str(), Error))
454 (*message)(LDPL_FATAL, "Failed to write the output file.");
455 if (options::generate_bc_file == options::BC_ONLY) {
465 if (!CodeGen->compile_to_file(&Temp, /*DisableOpt*/ false, /*DisableInline*/
466 false, /*DisableGVNLoadPRE*/ false, Error))
467 (*message)(LDPL_ERROR, "Could not produce a combined object file\n");
472 for (std::list<claimed_file>::iterator I = Modules.begin(),
473 E = Modules.end(); I != E; ++I) {
474 for (unsigned i = 0; i != I->syms.size(); ++i) {
475 ld_plugin_symbol &sym = I->syms[i];
480 if ((*add_input_file)(ObjPath.c_str()) != LDPS_OK) {
481 (*message)(LDPL_ERROR, "Unable to add .o file to the link.");
482 (*message)(LDPL_ERROR, "File left behind in: %s", ObjPath.c_str());
486 if (!options::extra_library_path.empty() &&
487 set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) {
488 (*message)(LDPL_ERROR, "Unable to set the extra library path.");
492 if (options::obj_path.empty())
493 Cleanup.push_back(ObjPath);
498 static ld_plugin_status cleanup_hook(void) {
499 for (int i = 0, e = Cleanup.size(); i != e; ++i) {
500 std::error_code EC = sys::fs::remove(Cleanup[i]);
502 (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(),
503 EC.message().c_str());