diff --git a/tools/Makefile b/tools/Makefile index 909a54843b5..0cf613a3058 100644 --- a/tools/Makefile +++ b/tools/Makefile @@ -27,6 +27,10 @@ include $(LEVEL)/Makefile.config ifeq ($(ENABLE_PIC),1) PARALLEL_DIRS += lto + +ifdef BINUTILS_INCDIR +PARALLEL_DIRS += gold +endif endif include $(LEVEL)/Makefile.common diff --git a/tools/gold/Makefile b/tools/gold/Makefile new file mode 100644 index 00000000000..37a7e4ef7fc --- /dev/null +++ b/tools/gold/Makefile @@ -0,0 +1,29 @@ +#===- tools/gold/Makefile ----------------------------------*- Makefile -*-===## +# +# The LLVM Compiler Infrastructure +# +# This file is distributed under the University of Illinois Open Source +# License. See LICENSE.TXT for details. +# +##===----------------------------------------------------------------------===## + +LEVEL = ../.. +LIBRARYNAME = LLVMgold + +# Include this here so we can get the configuration of the targets +# that have been configured for construction. We have to do this +# early so we can set up LINK_COMPONENTS before including Makefile.rules +include $(LEVEL)/Makefile.config + +LINK_LIBS_IN_SHARED=1 +SHARED_LIBRARY = 1 +BUILD_ARCHIVE = 0 +DONT_BUILD_RELINKED = 1 + +LINK_COMPONENTS := + +include $(LEVEL)/Makefile.common + +# Because off_t is used in the public API, the largefile parts are required for +# ABI compatibility. +CXXFLAGS+=-I$(BINUTILS_INCDIR) -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -lLTO diff --git a/tools/gold/README.txt b/tools/gold/README.txt new file mode 100644 index 00000000000..6427d09c770 --- /dev/null +++ b/tools/gold/README.txt @@ -0,0 +1,17 @@ +This directory contains a plugin that is designed to work with binutils +gold linker. At present time, this is not the default linker in +binutils, and the default build of gold does not support plugins. + +Obtaining binutils: + + cvs -z 9 -d :pserver:anoncvs@sourceware.org:/cvs/src login + {enter "anoncvs" as the password} + cvs -z 9 -d :pserver:anoncvs@sourceware.org:/cvs/src co binutils + +This will create a src/ directory. Make a build/ directory and from +there configure binutils with "../src/configure --enable-gold --enable-plugins". +Then build binutils with "make all-gold". + +To build the LLVMgold plugin, configure LLVM with the option +--with-binutils-include=/path/to/binutils/src/include/ . To use the +plugin, run "ld-new --plugin /path/to/libLLVMgold.so". diff --git a/tools/gold/gold-plugin.cpp b/tools/gold/gold-plugin.cpp new file mode 100644 index 00000000000..8c4bf043d06 --- /dev/null +++ b/tools/gold/gold-plugin.cpp @@ -0,0 +1,327 @@ +//===-- 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 "plugin-api.h" + +#include "llvm-c/lto.h" + +#include "llvm/Support/raw_ostream.h" +#include "llvm/System/Path.h" + +#include +#include +#include +#include + +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_message message = discard_message; + + int api_version = 0; + int gold_version = 0; + + struct claimed_file { + lto_module_t M; + void *handle; + std::vector syms; + }; + + lto_codegen_model output_type = LTO_CODEGEN_PIC_MODEL_STATIC; + std::list Modules; + std::vector Cleanup; +} + +ld_plugin_status claim_file_hook(const ld_plugin_input_file *file, + int *claimed); +ld_plugin_status all_symbols_read_hook(void); +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; + bool registeredAllSymbolsRead = false; + bool registeredCleanup = 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_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: + (*message)(LDPL_WARNING, "Ignoring flag %s", 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; + + registeredAllSymbolsRead = true; + } 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; + + registeredCleanup = true; + } 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_MESSAGE: + message = tv->tv_u.tv_message; + break; + default: + break; + } + } + + if (!registeredClaimFile || !registeredAllSymbolsRead || !registeredCleanup || + !add_symbols || !get_symbols || !add_input_file) { + (*message)(LDPL_ERROR, "Not all hooks registered for 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. +ld_plugin_status claim_file_hook(const ld_plugin_input_file *file, + int *claimed) { + // If set, this means gold found IR in an ELF section. LLVM doesn't wrap its + // IR in ELF, so we know it's not us. + if (file->offset) + return LDPS_OK; + + if (!lto_module_is_object_file(file->name)) + return LDPS_OK; + + *claimed = 1; + Modules.resize(Modules.size() + 1); + claimed_file &cf = Modules.back(); + + cf.M = lto_module_create(file->name); + if (!cf.M) { + (*message)(LDPL_ERROR, "Failed to create LLVM module: %s", + lto_get_error_message()); + return LDPS_ERR; + } + cf.handle = file->handle; + unsigned sym_count = lto_module_get_num_symbols(cf.M); + cf.syms.reserve(sym_count); + + for (unsigned i = 0; i != sym_count; ++i) { + lto_symbol_attributes attrs = lto_module_get_symbol_attribute(cf.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(cf.M, i)); + 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; + 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.def = LDPK_WEAKDEF; + break; + default: + (*message)(LDPL_ERROR, "Unknown definition attribute: %d", definition); + return LDPS_ERR; + } + + // LLVM never emits COMDAT. + sym.size = 0; + sym.comdat_key = NULL; + + 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; + } + } + + 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. +ld_plugin_status all_symbols_read_hook(void) { + lto_code_gen_t cg = lto_codegen_create(); + + for (std::list::iterator I = Modules.begin(), + E = Modules.end(); I != E; ++I) + lto_codegen_add_module(cg, I->M); + + // 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. + if (output_type == LTO_CODEGEN_PIC_MODEL_STATIC) { + bool anySymbolsPreserved = false; + for (std::list::iterator I = Modules.begin(), + E = Modules.end(); I != E; ++I) { + (*get_symbols)(I->handle, I->syms.size(), &I->syms[0]); + for (unsigned i = 0, e = I->syms.size(); i != e; i++) { + (*message)(LDPL_WARNING, "def: %d visibility: %d resolution %d", + I->syms[i].def, I->syms[i].visibility, I->syms[i].resolution); + if (I->syms[i].resolution == LDPR_PREVAILING_DEF) { + lto_codegen_add_must_preserve_symbol(cg, I->syms[i].name); + anySymbolsPreserved = true; + } + } + } + + if (!anySymbolsPreserved) { + // This entire file is unnecessary! + lto_codegen_dispose(cg); + return LDPS_OK; + } + } + + lto_codegen_set_pic_model(cg, output_type); + lto_codegen_set_debug_model(cg, LTO_DEBUG_MODEL_DWARF); + + size_t bufsize = 0; + const char *buffer = static_cast(lto_codegen_compile(cg, + &bufsize)); + + std::string ErrMsg; + + sys::Path uniqueObjPath("/tmp/llvmgold.o"); + if (uniqueObjPath.createTemporaryFileOnDisk(true, &ErrMsg)) { + (*message)(LDPL_ERROR, "%s", ErrMsg.c_str()); + return LDPS_ERR; + } + raw_fd_ostream *objFile = new raw_fd_ostream(uniqueObjPath.c_str(), true, + ErrMsg); + if (!ErrMsg.empty()) { + delete objFile; + (*message)(LDPL_ERROR, "%s", ErrMsg.c_str()); + return LDPS_ERR; + } + + objFile->write(buffer, bufsize); + objFile->close(); + + lto_codegen_dispose(cg); + + if ((*add_input_file)(const_cast(uniqueObjPath.c_str())) != LDPS_OK) { + (*message)(LDPL_ERROR, "Unable to add .o file to the link."); + (*message)(LDPL_ERROR, "File left behind in: %s", uniqueObjPath.c_str()); + return LDPS_ERR; + } + + Cleanup.push_back(uniqueObjPath); + + return LDPS_OK; +} + +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; +}