//===-- gold-plugin.cpp - Plugin to gold for Link Time Optimization ------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This is a gold plugin for LLVM. It provides an LLVM implementation of the // interface described in http://gcc.gnu.org/wiki/whopr/driver . // //===----------------------------------------------------------------------===// #include "llvm/Config/config.h" #include "plugin-api.h" #include "llvm-c/lto.h" #include "llvm/ADT/OwningPtr.h" #include "llvm/Support/system_error.h" #include "llvm/Support/MemoryBuffer.h" #include "llvm/Support/ToolOutputFile.h" #include "llvm/Support/Errno.h" #include "llvm/Support/Path.h" #include "llvm/Support/Program.h" #include #include #include #include #include #include // Support Windows/MinGW crazyness. #ifdef _WIN32 # include # define lseek _lseek # define read _read #endif using namespace llvm; namespace { ld_plugin_status discard_message(int level, const char *format, ...) { // Die loudly. Recent versions of Gold pass ld_plugin_message as the first // callback in the transfer vector. This should never be called. abort(); } ld_plugin_add_symbols add_symbols = NULL; ld_plugin_get_symbols get_symbols = NULL; ld_plugin_add_input_file add_input_file = NULL; ld_plugin_add_input_library add_input_library = NULL; ld_plugin_set_extra_library_path set_extra_library_path = NULL; ld_plugin_get_view get_view = NULL; ld_plugin_message message = discard_message; int api_version = 0; int gold_version = 0; struct claimed_file { void *handle; std::vector syms; }; lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC; std::string output_name = ""; std::list Modules; std::vector Cleanup; lto_code_gen_t code_gen = NULL; } namespace options { enum generate_bc { BC_NO, BC_ALSO, BC_ONLY }; static bool generate_api_file = false; static generate_bc generate_bc_file = BC_NO; static std::string bc_path; static std::string obj_path; static std::string extra_library_path; static std::string triple; static std::string mcpu; // Additional options to pass into the code generator. // Note: This array will contain all plugin options which are not claimed // as plugin exclusive to pass to the code generator. // For example, "generate-api-file" and "as"options are for the plugin // use only and will not be passed. static std::vector extra; static void process_plugin_option(const char* opt_) { if (opt_ == NULL) return; llvm::StringRef opt = opt_; if (opt == "generate-api-file") { generate_api_file = true; } else if (opt.startswith("mcpu=")) { mcpu = opt.substr(strlen("mcpu=")); } else if (opt.startswith("extra-library-path=")) { extra_library_path = opt.substr(strlen("extra_library_path=")); } else if (opt.startswith("mtriple=")) { triple = opt.substr(strlen("mtriple=")); } else if (opt.startswith("obj-path=")) { obj_path = opt.substr(strlen("obj-path=")); } else if (opt == "emit-llvm") { generate_bc_file = BC_ONLY; } else if (opt == "also-emit-llvm") { generate_bc_file = BC_ALSO; } else if (opt.startswith("also-emit-llvm=")) { llvm::StringRef path = opt.substr(strlen("also-emit-llvm=")); generate_bc_file = BC_ALSO; if (!bc_path.empty()) { (*message)(LDPL_WARNING, "Path to the output IL file specified twice. " "Discarding %s", opt_); } else { bc_path = path; } } else { // Save this option to pass to the code generator. extra.push_back(opt); } } } static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file, int *claimed); static ld_plugin_status all_symbols_read_hook(void); static ld_plugin_status cleanup_hook(void); extern "C" ld_plugin_status onload(ld_plugin_tv *tv); ld_plugin_status onload(ld_plugin_tv *tv) { // We're given a pointer to the first transfer vector. We read through them // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values // contain pointers to functions that we need to call to register our own // hooks. The others are addresses of functions we can use to call into gold // for services. bool registeredClaimFile = false; for (; tv->tv_tag != LDPT_NULL; ++tv) { switch (tv->tv_tag) { case LDPT_API_VERSION: api_version = tv->tv_u.tv_val; break; case LDPT_GOLD_VERSION: // major * 100 + minor gold_version = tv->tv_u.tv_val; break; case LDPT_OUTPUT_NAME: output_name = tv->tv_u.tv_string; break; case LDPT_LINKER_OUTPUT: switch (tv->tv_u.tv_val) { case LDPO_REL: // .o case LDPO_DYN: // .so output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC; break; case LDPO_EXEC: // .exe output_type = LTO_CODEGEN_PIC_MODEL_STATIC; break; default: (*message)(LDPL_ERROR, "Unknown output file type %d", tv->tv_u.tv_val); return LDPS_ERR; } // TODO: add an option to disable PIC. //output_type = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC; break; case LDPT_OPTION: options::process_plugin_option(tv->tv_u.tv_string); break; case LDPT_REGISTER_CLAIM_FILE_HOOK: { ld_plugin_register_claim_file callback; callback = tv->tv_u.tv_register_claim_file; if ((*callback)(claim_file_hook) != LDPS_OK) return LDPS_ERR; registeredClaimFile = true; } break; case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: { ld_plugin_register_all_symbols_read callback; callback = tv->tv_u.tv_register_all_symbols_read; if ((*callback)(all_symbols_read_hook) != LDPS_OK) return LDPS_ERR; code_gen = lto_codegen_create(); } break; case LDPT_REGISTER_CLEANUP_HOOK: { ld_plugin_register_cleanup callback; callback = tv->tv_u.tv_register_cleanup; if ((*callback)(cleanup_hook) != LDPS_OK) return LDPS_ERR; } break; case LDPT_ADD_SYMBOLS: add_symbols = tv->tv_u.tv_add_symbols; break; case LDPT_GET_SYMBOLS: get_symbols = tv->tv_u.tv_get_symbols; break; case LDPT_ADD_INPUT_FILE: add_input_file = tv->tv_u.tv_add_input_file; break; case LDPT_ADD_INPUT_LIBRARY: add_input_library = tv->tv_u.tv_add_input_file; break; case LDPT_SET_EXTRA_LIBRARY_PATH: set_extra_library_path = tv->tv_u.tv_set_extra_library_path; break; case LDPT_GET_VIEW: get_view = tv->tv_u.tv_get_view; break; case LDPT_MESSAGE: message = tv->tv_u.tv_message; break; default: break; } } if (!registeredClaimFile) { (*message)(LDPL_ERROR, "register_claim_file not passed to LLVMgold."); return LDPS_ERR; } if (!add_symbols) { (*message)(LDPL_ERROR, "add_symbols not passed to LLVMgold."); return LDPS_ERR; } return LDPS_OK; } /// claim_file_hook - called by gold to see whether this file is one that /// our plugin can handle. We'll try to open it and register all the symbols /// with add_symbol if possible. static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file, int *claimed) { lto_module_t M; const void *view; OwningPtr buffer; if (get_view) { if (get_view(file->handle, &view) != LDPS_OK) { (*message)(LDPL_ERROR, "Failed to get a view of %s", file->name); return LDPS_ERR; } } else { off_t offset = 0; // Gold has found what might be IR part-way inside of a file, such as // an .a archive. if (file->offset) { offset = file->offset; } if (error_code ec = MemoryBuffer::getOpenFile(file->fd, file->name, buffer, file->filesize, -1, offset, false)) { (*message)(LDPL_ERROR, ec.message().c_str()); return LDPS_ERR; } view = buffer->getBufferStart(); } if (!lto_module_is_object_file_in_memory(view, file->filesize)) return LDPS_OK; M = lto_module_create_from_memory(view, file->filesize); if (!M) { if (const char* msg = lto_get_error_message()) { (*message)(LDPL_ERROR, "LLVM gold plugin has failed to create LTO module: %s", msg); return LDPS_ERR; } return LDPS_OK; } *claimed = 1; Modules.resize(Modules.size() + 1); claimed_file &cf = Modules.back(); if (!options::triple.empty()) lto_module_set_target_triple(M, options::triple.c_str()); cf.handle = file->handle; unsigned sym_count = lto_module_get_num_symbols(M); cf.syms.reserve(sym_count); for (unsigned i = 0; i != sym_count; ++i) { lto_symbol_attributes attrs = lto_module_get_symbol_attribute(M, i); if ((attrs & LTO_SYMBOL_SCOPE_MASK) == LTO_SYMBOL_SCOPE_INTERNAL) continue; cf.syms.push_back(ld_plugin_symbol()); ld_plugin_symbol &sym = cf.syms.back(); sym.name = const_cast(lto_module_get_symbol_name(M, i)); sym.name = strdup(sym.name); sym.version = NULL; int scope = attrs & LTO_SYMBOL_SCOPE_MASK; switch (scope) { case LTO_SYMBOL_SCOPE_HIDDEN: sym.visibility = LDPV_HIDDEN; break; case LTO_SYMBOL_SCOPE_PROTECTED: sym.visibility = LDPV_PROTECTED; break; case 0: // extern case LTO_SYMBOL_SCOPE_DEFAULT: sym.visibility = LDPV_DEFAULT; break; default: (*message)(LDPL_ERROR, "Unknown scope attribute: %d", scope); return LDPS_ERR; } int definition = attrs & LTO_SYMBOL_DEFINITION_MASK; sym.comdat_key = NULL; switch (definition) { case LTO_SYMBOL_DEFINITION_REGULAR: sym.def = LDPK_DEF; break; case LTO_SYMBOL_DEFINITION_UNDEFINED: sym.def = LDPK_UNDEF; break; case LTO_SYMBOL_DEFINITION_TENTATIVE: sym.def = LDPK_COMMON; break; case LTO_SYMBOL_DEFINITION_WEAK: sym.comdat_key = sym.name; sym.def = LDPK_WEAKDEF; break; case LTO_SYMBOL_DEFINITION_WEAKUNDEF: sym.def = LDPK_WEAKUNDEF; break; default: (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition); return LDPS_ERR; } sym.size = 0; sym.resolution = LDPR_UNKNOWN; } cf.syms.reserve(cf.syms.size()); if (!cf.syms.empty()) { if ((*add_symbols)(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) { (*message)(LDPL_ERROR, "Unable to add symbols!"); return LDPS_ERR; } } if (code_gen) lto_codegen_add_module(code_gen, M); lto_module_dispose(M); return LDPS_OK; } /// all_symbols_read_hook - gold informs us that all symbols have been read. /// At this point, we use get_symbols to see if any of our definitions have /// been overridden by a native object file. Then, perform optimization and /// codegen. static ld_plugin_status all_symbols_read_hook(void) { std::ofstream api_file; assert(code_gen); if (options::generate_api_file) { api_file.open("apifile.txt", std::ofstream::out | std::ofstream::trunc); if (!api_file.is_open()) { (*message)(LDPL_FATAL, "Unable to open apifile.txt for writing."); abort(); } } // If we don't preserve any symbols, libLTO will assume that all symbols are // needed. Keep all symbols unless we're producing a final executable. bool anySymbolsPreserved = false; for (std::list::iterator I = Modules.begin(), E = Modules.end(); I != E; ++I) { if (I->syms.empty()) continue; (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]); for (unsigned i = 0, e = I->syms.size(); i != e; i++) { if (I->syms[i].resolution == LDPR_PREVAILING_DEF) { lto_codegen_add_must_preserve_symbol(code_gen, I->syms[i].name); anySymbolsPreserved = true; if (options::generate_api_file) api_file << I->syms[i].name << "\n"; } } } if (options::generate_api_file) api_file.close(); if (!anySymbolsPreserved) { // All of the IL is unnecessary! lto_codegen_dispose(code_gen); return LDPS_OK; } lto_codegen_set_pic_model(code_gen, output_type); lto_codegen_set_debug_model(code_gen, LTO_DEBUG_MODEL_DWARF); if (!options::mcpu.empty()) lto_codegen_set_cpu(code_gen, options::mcpu.c_str()); // Pass through extra options to the code generator. if (!options::extra.empty()) { for (std::vector::iterator it = options::extra.begin(); it != options::extra.end(); ++it) { lto_codegen_debug_options(code_gen, (*it).c_str()); } } if (options::generate_bc_file != options::BC_NO) { std::string path; if (options::generate_bc_file == options::BC_ONLY) path = output_name; else if (!options::bc_path.empty()) path = options::bc_path; else path = output_name + ".bc"; bool err = lto_codegen_write_merged_modules(code_gen, path.c_str()); if (err) (*message)(LDPL_FATAL, "Failed to write the output file."); if (options::generate_bc_file == options::BC_ONLY) exit(0); } const char *objPath; if (lto_codegen_compile_to_file(code_gen, &objPath)) { (*message)(LDPL_ERROR, "Could not produce a combined object file\n"); } lto_codegen_dispose(code_gen); for (std::list::iterator I = Modules.begin(), E = Modules.end(); I != E; ++I) { for (unsigned i = 0; i != I->syms.size(); ++i) { ld_plugin_symbol &sym = I->syms[i]; free(sym.name); } } if ((*add_input_file)(objPath) != LDPS_OK) { (*message)(LDPL_ERROR, "Unable to add .o file to the link."); (*message)(LDPL_ERROR, "File left behind in: %s", objPath); return LDPS_ERR; } if (!options::extra_library_path.empty() && set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK) { (*message)(LDPL_ERROR, "Unable to set the extra library path."); return LDPS_ERR; } if (options::obj_path.empty()) Cleanup.push_back(sys::Path(objPath)); return LDPS_OK; } static ld_plugin_status cleanup_hook(void) { std::string ErrMsg; for (int i = 0, e = Cleanup.size(); i != e; ++i) if (Cleanup[i].eraseFromDisk(false, &ErrMsg)) (*message)(LDPL_ERROR, "Failed to delete '%s': %s", Cleanup[i].c_str(), ErrMsg.c_str()); return LDPS_OK; }