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llvm-mirror/tools/gold/gold-plugin.cpp
Teresa Johnson 8baf80ada5 [gold] Match lld WPD behavior for shared library symbols and add test 
lld already marks shared library defs as ExportDynamic, which prevents
potentially unsafe devirtualization of symbols defined in shared
libraries. Match that behavior in the gold plugin, and add the same
test.

Depends on D96721.

Differential Revision: https://reviews.llvm.org/D96722
2021-02-17 15:28:49 -08:00

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//===-- gold-plugin.cpp - Plugin to gold for Link Time Optimization ------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// 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/ADT/Statistic.h"
#include "llvm/Bitcode/BitcodeReader.h"
#include "llvm/Bitcode/BitcodeWriter.h"
#include "llvm/CodeGen/CommandFlags.h"
#include "llvm/Config/config.h" // plugin-api.h requires HAVE_STDINT_H
#include "llvm/Config/llvm-config.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/LTO/Caching.h"
#include "llvm/LTO/LTO.h"
#include "llvm/Object/Error.h"
#include "llvm/Remarks/HotnessThresholdParser.h"
#include "llvm/Support/CachePruning.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/Threading.h"
#include "llvm/Support/raw_ostream.h"
#include <list>
#include <map>
#include <plugin-api.h>
#include <string>
#include <system_error>
#include <utility>
#include <vector>
// FIXME: remove this declaration when we stop maintaining Ubuntu Quantal and
// Precise and Debian Wheezy (binutils 2.23 is required)
#define LDPO_PIE 3
#define LDPT_GET_SYMBOLS_V3 28
// FIXME: Remove when binutils 2.31 (containing gold 1.16) is the minimum
// required version.
#define LDPT_GET_WRAP_SYMBOLS 32
using namespace llvm;
using namespace lto;
static codegen::RegisterCodeGenFlags CodeGenFlags;
// FIXME: Remove when binutils 2.31 (containing gold 1.16) is the minimum
// required version.
typedef enum ld_plugin_status (*ld_plugin_get_wrap_symbols)(
uint64_t *num_symbols, const char ***wrap_symbol_list);
static 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();
}
static ld_plugin_release_input_file release_input_file = nullptr;
static ld_plugin_get_input_file get_input_file = nullptr;
static ld_plugin_message message = discard_message;
static ld_plugin_get_wrap_symbols get_wrap_symbols = nullptr;
namespace {
struct claimed_file {
void *handle;
void *leader_handle;
std::vector<ld_plugin_symbol> syms;
off_t filesize;
std::string name;
};
/// RAII wrapper to manage opening and releasing of a ld_plugin_input_file.
struct PluginInputFile {
void *Handle;
std::unique_ptr<ld_plugin_input_file> File;
PluginInputFile(void *Handle) : Handle(Handle) {
File = std::make_unique<ld_plugin_input_file>();
if (get_input_file(Handle, File.get()) != LDPS_OK)
message(LDPL_FATAL, "Failed to get file information");
}
~PluginInputFile() {
// File would have been reset to nullptr if we moved this object
// to a new owner.
if (File)
if (release_input_file(Handle) != LDPS_OK)
message(LDPL_FATAL, "Failed to release file information");
}
ld_plugin_input_file &file() { return *File; }
PluginInputFile(PluginInputFile &&RHS) = default;
PluginInputFile &operator=(PluginInputFile &&RHS) = default;
};
struct ResolutionInfo {
bool CanOmitFromDynSym = true;
bool DefaultVisibility = true;
bool CanInline = true;
bool IsUsedInRegularObj = false;
};
}
static ld_plugin_add_symbols add_symbols = nullptr;
static ld_plugin_get_symbols get_symbols = nullptr;
static ld_plugin_add_input_file add_input_file = nullptr;
static ld_plugin_set_extra_library_path set_extra_library_path = nullptr;
static ld_plugin_get_view get_view = nullptr;
static bool IsExecutable = false;
static bool SplitSections = true;
static Optional<Reloc::Model> RelocationModel = None;
static std::string output_name = "";
static std::list<claimed_file> Modules;
static DenseMap<int, void *> FDToLeaderHandle;
static StringMap<ResolutionInfo> ResInfo;
static std::vector<std::string> Cleanup;
namespace options {
enum OutputType {
OT_NORMAL,
OT_DISABLE,
OT_BC_ONLY,
OT_ASM_ONLY,
OT_SAVE_TEMPS
};
static OutputType TheOutputType = OT_NORMAL;
static unsigned OptLevel = 2;
// Currently only affects ThinLTO, where the default is the max cores in the
// system. See llvm::get_threadpool_strategy() for acceptable values.
static std::string Parallelism;
// Default regular LTO codegen parallelism (number of partitions).
static unsigned ParallelCodeGenParallelismLevel = 1;
#ifdef NDEBUG
static bool DisableVerify = true;
#else
static bool DisableVerify = false;
#endif
static std::string obj_path;
static std::string extra_library_path;
static std::string triple;
static std::string mcpu;
// When the thinlto plugin option is specified, only read the function
// the information from intermediate files and write a combined
// global index for the ThinLTO backends.
static bool thinlto = false;
// If false, all ThinLTO backend compilations through code gen are performed
// using multiple threads in the gold-plugin, before handing control back to
// gold. If true, write individual backend index files which reflect
// the import decisions, and exit afterwards. The assumption is
// that the build system will launch the backend processes.
static bool thinlto_index_only = false;
// If non-empty, holds the name of a file in which to write the list of
// oject files gold selected for inclusion in the link after symbol
// resolution (i.e. they had selected symbols). This will only be non-empty
// in the thinlto_index_only case. It is used to identify files, which may
// have originally been within archive libraries specified via
// --start-lib/--end-lib pairs, that should be included in the final
// native link process (since intervening function importing and inlining
// may change the symbol resolution detected in the final link and which
// files to include out of --start-lib/--end-lib libraries as a result).
static std::string thinlto_linked_objects_file;
// If true, when generating individual index files for distributed backends,
// also generate a "${bitcodefile}.imports" file at the same location for each
// bitcode file, listing the files it imports from in plain text. This is to
// support distributed build file staging.
static bool thinlto_emit_imports_files = false;
// Option to control where files for a distributed backend (the individual
// index files and optional imports files) are created.
// If specified, expects a string of the form "oldprefix:newprefix", and
// instead of generating these files in the same directory path as the
// corresponding bitcode file, will use a path formed by replacing the
// bitcode file's path prefix matching oldprefix with newprefix.
static std::string thinlto_prefix_replace;
// Option to control the name of modules encoded in the individual index
// files for a distributed backend. This enables the use of minimized
// bitcode files for the thin link, assuming the name of the full bitcode
// file used in the backend differs just in some part of the file suffix.
// If specified, expects a string of the form "oldsuffix:newsuffix".
static std::string thinlto_object_suffix_replace;
// Optional path to a directory for caching ThinLTO objects.
static std::string cache_dir;
// Optional pruning policy for ThinLTO caches.
static std::string cache_policy;
// 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.
static std::vector<const char *> extra;
// Sample profile file path
static std::string sample_profile;
// New pass manager
static bool new_pass_manager = LLVM_ENABLE_NEW_PASS_MANAGER;
// Debug new pass manager
static bool debug_pass_manager = false;
// Directory to store the .dwo files.
static std::string dwo_dir;
/// Statistics output filename.
static std::string stats_file;
// Asserts that LTO link has whole program visibility
static bool whole_program_visibility = false;
// Optimization remarks filename, accepted passes and hotness options
static std::string RemarksFilename;
static std::string RemarksPasses;
static bool RemarksWithHotness = false;
static Optional<uint64_t> RemarksHotnessThreshold = 0;
static std::string RemarksFormat;
// Context sensitive PGO options.
static std::string cs_profile_path;
static bool cs_pgo_gen = false;
static void process_plugin_option(const char *opt_)
{
if (opt_ == nullptr)
return;
llvm::StringRef opt = opt_;
if (opt.consume_front("mcpu=")) {
mcpu = std::string(opt);
} else if (opt.consume_front("extra-library-path=")) {
extra_library_path = std::string(opt);
} else if (opt.consume_front("mtriple=")) {
triple = std::string(opt);
} else if (opt.consume_front("obj-path=")) {
obj_path = std::string(opt);
} else if (opt == "emit-llvm") {
TheOutputType = OT_BC_ONLY;
} else if (opt == "save-temps") {
TheOutputType = OT_SAVE_TEMPS;
} else if (opt == "disable-output") {
TheOutputType = OT_DISABLE;
} else if (opt == "emit-asm") {
TheOutputType = OT_ASM_ONLY;
} else if (opt == "thinlto") {
thinlto = true;
} else if (opt == "thinlto-index-only") {
thinlto_index_only = true;
} else if (opt.consume_front("thinlto-index-only=")) {
thinlto_index_only = true;
thinlto_linked_objects_file = std::string(opt);
} else if (opt == "thinlto-emit-imports-files") {
thinlto_emit_imports_files = true;
} else if (opt.consume_front("thinlto-prefix-replace=")) {
thinlto_prefix_replace = std::string(opt);
if (thinlto_prefix_replace.find(';') == std::string::npos)
message(LDPL_FATAL, "thinlto-prefix-replace expects 'old;new' format");
} else if (opt.consume_front("thinlto-object-suffix-replace=")) {
thinlto_object_suffix_replace = std::string(opt);
if (thinlto_object_suffix_replace.find(';') == std::string::npos)
message(LDPL_FATAL,
"thinlto-object-suffix-replace expects 'old;new' format");
} else if (opt.consume_front("cache-dir=")) {
cache_dir = std::string(opt);
} else if (opt.consume_front("cache-policy=")) {
cache_policy = std::string(opt);
} else if (opt.size() == 2 && opt[0] == 'O') {
if (opt[1] < '0' || opt[1] > '3')
message(LDPL_FATAL, "Optimization level must be between 0 and 3");
OptLevel = opt[1] - '0';
} else if (opt.consume_front("jobs=")) {
Parallelism = std::string(opt);
if (!get_threadpool_strategy(opt))
message(LDPL_FATAL, "Invalid parallelism level: %s",
Parallelism.c_str());
} else if (opt.consume_front("lto-partitions=")) {
if (opt.getAsInteger(10, ParallelCodeGenParallelismLevel))
message(LDPL_FATAL, "Invalid codegen partition level: %s", opt_ + 5);
} else if (opt == "disable-verify") {
DisableVerify = true;
} else if (opt.consume_front("sample-profile=")) {
sample_profile = std::string(opt);
} else if (opt == "cs-profile-generate") {
cs_pgo_gen = true;
} else if (opt.consume_front("cs-profile-path=")) {
cs_profile_path = std::string(opt);
} else if (opt == "new-pass-manager") {
new_pass_manager = true;
} else if (opt == "legacy-pass-manager") {
new_pass_manager = false;
} else if (opt == "debug-pass-manager") {
debug_pass_manager = true;
} else if (opt == "whole-program-visibility") {
whole_program_visibility = true;
} else if (opt.consume_front("dwo_dir=")) {
dwo_dir = std::string(opt);
} else if (opt.consume_front("opt-remarks-filename=")) {
RemarksFilename = std::string(opt);
} else if (opt.consume_front("opt-remarks-passes=")) {
RemarksPasses = std::string(opt);
} else if (opt == "opt-remarks-with-hotness") {
RemarksWithHotness = true;
} else if (opt.consume_front("opt-remarks-hotness-threshold=")) {
auto ResultOrErr = remarks::parseHotnessThresholdOption(opt);
if (!ResultOrErr)
message(LDPL_FATAL, "Invalid remarks hotness threshold: %s", opt);
else
RemarksHotnessThreshold = *ResultOrErr;
} else if (opt.consume_front("opt-remarks-format=")) {
RemarksFormat = std::string(opt);
} else if (opt.consume_front("stats-file=")) {
stats_file = std::string(opt);
} else {
// Save this option to pass to the code generator.
// ParseCommandLineOptions() expects argv[0] to be program name. Lazily
// add that.
if (extra.empty())
extra.push_back("LLVMgold");
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) {
InitializeAllTargetInfos();
InitializeAllTargets();
InitializeAllTargetMCs();
InitializeAllAsmParsers();
InitializeAllAsmPrinters();
// 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;
for (; tv->tv_tag != LDPT_NULL; ++tv) {
// Cast tv_tag to int to allow values not in "enum ld_plugin_tag", like, for
// example, LDPT_GET_SYMBOLS_V3 when building against an older plugin-api.h
// header.
switch (static_cast<int>(tv->tv_tag)) {
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
IsExecutable = false;
SplitSections = false;
break;
case LDPO_DYN: // .so
IsExecutable = false;
RelocationModel = Reloc::PIC_;
break;
case LDPO_PIE: // position independent executable
IsExecutable = true;
RelocationModel = Reloc::PIC_;
break;
case LDPO_EXEC: // .exe
IsExecutable = true;
RelocationModel = Reloc::Static;
break;
default:
message(LDPL_ERROR, "Unknown output file type %d", tv->tv_u.tv_val);
return LDPS_ERR;
}
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;
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;
} break;
case LDPT_GET_INPUT_FILE:
get_input_file = tv->tv_u.tv_get_input_file;
break;
case LDPT_RELEASE_INPUT_FILE:
release_input_file = tv->tv_u.tv_release_input_file;
break;
case LDPT_ADD_SYMBOLS:
add_symbols = tv->tv_u.tv_add_symbols;
break;
case LDPT_GET_SYMBOLS_V2:
// Do not override get_symbols_v3 with get_symbols_v2.
if (!get_symbols)
get_symbols = tv->tv_u.tv_get_symbols;
break;
case LDPT_GET_SYMBOLS_V3:
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_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;
case LDPT_GET_WRAP_SYMBOLS:
// FIXME: When binutils 2.31 (containing gold 1.16) is the minimum
// required version, this should be changed to:
// get_wrap_symbols = tv->tv_u.tv_get_wrap_symbols;
get_wrap_symbols =
(ld_plugin_get_wrap_symbols)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;
}
if (!RegisteredAllSymbolsRead)
return LDPS_OK;
if (!get_input_file) {
message(LDPL_ERROR, "get_input_file not passed to LLVMgold.");
return LDPS_ERR;
}
if (!release_input_file) {
message(LDPL_ERROR, "release_input_file not passed to LLVMgold.");
return LDPS_ERR;
}
return LDPS_OK;
}
static void diagnosticHandler(const DiagnosticInfo &DI) {
std::string ErrStorage;
{
raw_string_ostream OS(ErrStorage);
DiagnosticPrinterRawOStream DP(OS);
DI.print(DP);
}
ld_plugin_level Level;
switch (DI.getSeverity()) {
case DS_Error:
Level = LDPL_FATAL;
break;
case DS_Warning:
Level = LDPL_WARNING;
break;
case DS_Note:
case DS_Remark:
Level = LDPL_INFO;
break;
}
message(Level, "LLVM gold plugin: %s", ErrStorage.c_str());
}
static void check(Error E, std::string Msg = "LLVM gold plugin") {
handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) -> Error {
message(LDPL_FATAL, "%s: %s", Msg.c_str(), EIB.message().c_str());
return Error::success();
});
}
template <typename T> static T check(Expected<T> E) {
if (E)
return std::move(*E);
check(E.takeError());
return T();
}
/// 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) {
MemoryBufferRef BufferRef;
std::unique_ptr<MemoryBuffer> Buffer;
if (get_view) {
const void *view;
if (get_view(file->handle, &view) != LDPS_OK) {
message(LDPL_ERROR, "Failed to get a view of %s", file->name);
return LDPS_ERR;
}
BufferRef =
MemoryBufferRef(StringRef((const char *)view, file->filesize), "");
} else {
int64_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;
}
ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
MemoryBuffer::getOpenFileSlice(sys::fs::convertFDToNativeFile(file->fd),
file->name, file->filesize, offset);
if (std::error_code EC = BufferOrErr.getError()) {
message(LDPL_ERROR, EC.message().c_str());
return LDPS_ERR;
}
Buffer = std::move(BufferOrErr.get());
BufferRef = Buffer->getMemBufferRef();
}
*claimed = 1;
Expected<std::unique_ptr<InputFile>> ObjOrErr = InputFile::create(BufferRef);
if (!ObjOrErr) {
handleAllErrors(ObjOrErr.takeError(), [&](const ErrorInfoBase &EI) {
std::error_code EC = EI.convertToErrorCode();
if (EC == object::object_error::invalid_file_type ||
EC == object::object_error::bitcode_section_not_found)
*claimed = 0;
else
message(LDPL_FATAL,
"LLVM gold plugin has failed to create LTO module: %s",
EI.message().c_str());
});
return *claimed ? LDPS_ERR : LDPS_OK;
}
std::unique_ptr<InputFile> Obj = std::move(*ObjOrErr);
Modules.emplace_back();
claimed_file &cf = Modules.back();
cf.handle = file->handle;
// Keep track of the first handle for each file descriptor, since there are
// multiple in the case of an archive. This is used later in the case of
// ThinLTO parallel backends to ensure that each file is only opened and
// released once.
auto LeaderHandle =
FDToLeaderHandle.insert(std::make_pair(file->fd, file->handle)).first;
cf.leader_handle = LeaderHandle->second;
// Save the filesize since for parallel ThinLTO backends we can only
// invoke get_input_file once per archive (only for the leader handle).
cf.filesize = file->filesize;
// In the case of an archive library, all but the first member must have a
// non-zero offset, which we can append to the file name to obtain a
// unique name.
cf.name = file->name;
if (file->offset)
cf.name += ".llvm." + std::to_string(file->offset) + "." +
sys::path::filename(Obj->getSourceFileName()).str();
for (auto &Sym : Obj->symbols()) {
cf.syms.push_back(ld_plugin_symbol());
ld_plugin_symbol &sym = cf.syms.back();
sym.version = nullptr;
StringRef Name = Sym.getName();
sym.name = strdup(Name.str().c_str());
ResolutionInfo &Res = ResInfo[Name];
Res.CanOmitFromDynSym &= Sym.canBeOmittedFromSymbolTable();
sym.visibility = LDPV_DEFAULT;
GlobalValue::VisibilityTypes Vis = Sym.getVisibility();
if (Vis != GlobalValue::DefaultVisibility)
Res.DefaultVisibility = false;
switch (Vis) {
case GlobalValue::DefaultVisibility:
break;
case GlobalValue::HiddenVisibility:
sym.visibility = LDPV_HIDDEN;
break;
case GlobalValue::ProtectedVisibility:
sym.visibility = LDPV_PROTECTED;
break;
}
if (Sym.isUndefined()) {
sym.def = LDPK_UNDEF;
if (Sym.isWeak())
sym.def = LDPK_WEAKUNDEF;
} else if (Sym.isCommon())
sym.def = LDPK_COMMON;
else if (Sym.isWeak())
sym.def = LDPK_WEAKDEF;
else
sym.def = LDPK_DEF;
sym.size = 0;
sym.comdat_key = nullptr;
int CI = Sym.getComdatIndex();
if (CI != -1) {
StringRef C = Obj->getComdatTable()[CI];
sym.comdat_key = strdup(C.str().c_str());
}
sym.resolution = LDPR_UNKNOWN;
}
if (!cf.syms.empty()) {
if (add_symbols(cf.handle, cf.syms.size(), cf.syms.data()) != LDPS_OK) {
message(LDPL_ERROR, "Unable to add symbols!");
return LDPS_ERR;
}
}
// Handle any --wrap options passed to gold, which are than passed
// along to the plugin.
if (get_wrap_symbols) {
const char **wrap_symbols;
uint64_t count = 0;
if (get_wrap_symbols(&count, &wrap_symbols) != LDPS_OK) {
message(LDPL_ERROR, "Unable to get wrap symbols!");
return LDPS_ERR;
}
for (uint64_t i = 0; i < count; i++) {
StringRef Name = wrap_symbols[i];
ResolutionInfo &Res = ResInfo[Name];
ResolutionInfo &WrapRes = ResInfo["__wrap_" + Name.str()];
ResolutionInfo &RealRes = ResInfo["__real_" + Name.str()];
// Tell LTO not to inline symbols that will be overwritten.
Res.CanInline = false;
RealRes.CanInline = false;
// Tell LTO not to eliminate symbols that will be used after renaming.
Res.IsUsedInRegularObj = true;
WrapRes.IsUsedInRegularObj = true;
}
}
return LDPS_OK;
}
static void freeSymName(ld_plugin_symbol &Sym) {
free(Sym.name);
free(Sym.comdat_key);
Sym.name = nullptr;
Sym.comdat_key = nullptr;
}
/// Helper to get a file's symbols and a view into it via gold callbacks.
static const void *getSymbolsAndView(claimed_file &F) {
ld_plugin_status status = get_symbols(F.handle, F.syms.size(), F.syms.data());
if (status == LDPS_NO_SYMS)
return nullptr;
if (status != LDPS_OK)
message(LDPL_FATAL, "Failed to get symbol information");
const void *View;
if (get_view(F.handle, &View) != LDPS_OK)
message(LDPL_FATAL, "Failed to get a view of file");
return View;
}
/// Parse the thinlto-object-suffix-replace option into the \p OldSuffix and
/// \p NewSuffix strings, if it was specified.
static void getThinLTOOldAndNewSuffix(std::string &OldSuffix,
std::string &NewSuffix) {
assert(options::thinlto_object_suffix_replace.empty() ||
options::thinlto_object_suffix_replace.find(';') != StringRef::npos);
StringRef SuffixReplace = options::thinlto_object_suffix_replace;
auto Split = SuffixReplace.split(';');
OldSuffix = std::string(Split.first);
NewSuffix = std::string(Split.second);
}
/// Given the original \p Path to an output file, replace any filename
/// suffix matching \p OldSuffix with \p NewSuffix.
static std::string getThinLTOObjectFileName(StringRef Path, StringRef OldSuffix,
StringRef NewSuffix) {
if (Path.consume_back(OldSuffix))
return (Path + NewSuffix).str();
return std::string(Path);
}
// Returns true if S is valid as a C language identifier.
static bool isValidCIdentifier(StringRef S) {
return !S.empty() && (isAlpha(S[0]) || S[0] == '_') &&
std::all_of(S.begin() + 1, S.end(),
[](char C) { return C == '_' || isAlnum(C); });
}
static bool isUndefined(ld_plugin_symbol &Sym) {
return Sym.def == LDPK_UNDEF || Sym.def == LDPK_WEAKUNDEF;
}
static void addModule(LTO &Lto, claimed_file &F, const void *View,
StringRef Filename) {
MemoryBufferRef BufferRef(StringRef((const char *)View, F.filesize),
Filename);
Expected<std::unique_ptr<InputFile>> ObjOrErr = InputFile::create(BufferRef);
if (!ObjOrErr)
message(LDPL_FATAL, "Could not read bitcode from file : %s",
toString(ObjOrErr.takeError()).c_str());
unsigned SymNum = 0;
std::unique_ptr<InputFile> Input = std::move(ObjOrErr.get());
auto InputFileSyms = Input->symbols();
assert(InputFileSyms.size() == F.syms.size());
std::vector<SymbolResolution> Resols(F.syms.size());
for (ld_plugin_symbol &Sym : F.syms) {
const InputFile::Symbol &InpSym = InputFileSyms[SymNum];
SymbolResolution &R = Resols[SymNum++];
ld_plugin_symbol_resolution Resolution =
(ld_plugin_symbol_resolution)Sym.resolution;
ResolutionInfo &Res = ResInfo[Sym.name];
switch (Resolution) {
case LDPR_UNKNOWN:
llvm_unreachable("Unexpected resolution");
case LDPR_RESOLVED_IR:
case LDPR_RESOLVED_EXEC:
case LDPR_PREEMPTED_IR:
case LDPR_PREEMPTED_REG:
case LDPR_UNDEF:
break;
case LDPR_RESOLVED_DYN:
R.ExportDynamic = true;
break;
case LDPR_PREVAILING_DEF_IRONLY:
R.Prevailing = !isUndefined(Sym);
break;
case LDPR_PREVAILING_DEF:
R.Prevailing = !isUndefined(Sym);
R.VisibleToRegularObj = true;
break;
case LDPR_PREVAILING_DEF_IRONLY_EXP:
R.Prevailing = !isUndefined(Sym);
// Identify symbols exported dynamically, and that therefore could be
// referenced by a shared library not visible to the linker.
R.ExportDynamic = true;
if (!Res.CanOmitFromDynSym)
R.VisibleToRegularObj = true;
break;
}
// If the symbol has a C identifier section name, we need to mark
// it as visible to a regular object so that LTO will keep it around
// to ensure the linker generates special __start_<secname> and
// __stop_<secname> symbols which may be used elsewhere.
if (isValidCIdentifier(InpSym.getSectionName()))
R.VisibleToRegularObj = true;
if (Resolution != LDPR_RESOLVED_DYN && Resolution != LDPR_UNDEF &&
(IsExecutable || !Res.DefaultVisibility))
R.FinalDefinitionInLinkageUnit = true;
if (!Res.CanInline)
R.LinkerRedefined = true;
if (Res.IsUsedInRegularObj)
R.VisibleToRegularObj = true;
freeSymName(Sym);
}
check(Lto.add(std::move(Input), Resols),
std::string("Failed to link module ") + F.name);
}
static void recordFile(const std::string &Filename, bool TempOutFile) {
if (add_input_file(Filename.c_str()) != LDPS_OK)
message(LDPL_FATAL,
"Unable to add .o file to the link. File left behind in: %s",
Filename.c_str());
if (TempOutFile)
Cleanup.push_back(Filename);
}
/// Return the desired output filename given a base input name, a flag
/// indicating whether a temp file should be generated, and an optional task id.
/// The new filename generated is returned in \p NewFilename.
static int getOutputFileName(StringRef InFilename, bool TempOutFile,
SmallString<128> &NewFilename, int TaskID) {
int FD = -1;
if (TempOutFile) {
std::error_code EC =
sys::fs::createTemporaryFile("lto-llvm", "o", FD, NewFilename);
if (EC)
message(LDPL_FATAL, "Could not create temporary file: %s",
EC.message().c_str());
} else {
NewFilename = InFilename;
if (TaskID > 0)
NewFilename += utostr(TaskID);
std::error_code EC =
sys::fs::openFileForWrite(NewFilename, FD, sys::fs::CD_CreateAlways);
if (EC)
message(LDPL_FATAL, "Could not open file %s: %s", NewFilename.c_str(),
EC.message().c_str());
}
return FD;
}
static CodeGenOpt::Level getCGOptLevel() {
switch (options::OptLevel) {
case 0:
return CodeGenOpt::None;
case 1:
return CodeGenOpt::Less;
case 2:
return CodeGenOpt::Default;
case 3:
return CodeGenOpt::Aggressive;
}
llvm_unreachable("Invalid optimization level");
}
/// Parse the thinlto_prefix_replace option into the \p OldPrefix and
/// \p NewPrefix strings, if it was specified.
static void getThinLTOOldAndNewPrefix(std::string &OldPrefix,
std::string &NewPrefix) {
StringRef PrefixReplace = options::thinlto_prefix_replace;
assert(PrefixReplace.empty() || PrefixReplace.find(';') != StringRef::npos);
auto Split = PrefixReplace.split(';');
OldPrefix = std::string(Split.first);
NewPrefix = std::string(Split.second);
}
/// Creates instance of LTO.
/// OnIndexWrite is callback to let caller know when LTO writes index files.
/// LinkedObjectsFile is an output stream to write the list of object files for
/// the final ThinLTO linking. Can be nullptr.
static std::unique_ptr<LTO> createLTO(IndexWriteCallback OnIndexWrite,
raw_fd_ostream *LinkedObjectsFile) {
Config Conf;
ThinBackend Backend;
Conf.CPU = options::mcpu;
Conf.Options = codegen::InitTargetOptionsFromCodeGenFlags(Triple());
// Disable the new X86 relax relocations since gold might not support them.
// FIXME: Check the gold version or add a new option to enable them.
Conf.Options.RelaxELFRelocations = false;
// Toggle function/data sections.
if (!codegen::getExplicitFunctionSections())
Conf.Options.FunctionSections = SplitSections;
if (!codegen::getExplicitDataSections())
Conf.Options.DataSections = SplitSections;
Conf.MAttrs = codegen::getMAttrs();
Conf.RelocModel = RelocationModel;
Conf.CodeModel = codegen::getExplicitCodeModel();
Conf.CGOptLevel = getCGOptLevel();
Conf.DisableVerify = options::DisableVerify;
Conf.OptLevel = options::OptLevel;
Conf.PTO.LoopVectorization = options::OptLevel > 1;
Conf.PTO.SLPVectorization = options::OptLevel > 1;
Conf.AlwaysEmitRegularLTOObj = !options::obj_path.empty();
if (options::thinlto_index_only) {
std::string OldPrefix, NewPrefix;
getThinLTOOldAndNewPrefix(OldPrefix, NewPrefix);
Backend = createWriteIndexesThinBackend(OldPrefix, NewPrefix,
options::thinlto_emit_imports_files,
LinkedObjectsFile, OnIndexWrite);
} else {
Backend = createInProcessThinBackend(
llvm::heavyweight_hardware_concurrency(options::Parallelism));
}
Conf.OverrideTriple = options::triple;
Conf.DefaultTriple = sys::getDefaultTargetTriple();
Conf.DiagHandler = diagnosticHandler;
switch (options::TheOutputType) {
case options::OT_NORMAL:
break;
case options::OT_DISABLE:
Conf.PreOptModuleHook = [](size_t Task, const Module &M) { return false; };
break;
case options::OT_BC_ONLY:
Conf.PostInternalizeModuleHook = [](size_t Task, const Module &M) {
std::error_code EC;
SmallString<128> TaskFilename;
getOutputFileName(output_name, /* TempOutFile */ false, TaskFilename,
Task);
raw_fd_ostream OS(TaskFilename, EC, sys::fs::OpenFlags::OF_None);
if (EC)
message(LDPL_FATAL, "Failed to write the output file.");
WriteBitcodeToFile(M, OS, /* ShouldPreserveUseListOrder */ false);
return false;
};
break;
case options::OT_SAVE_TEMPS:
check(Conf.addSaveTemps(output_name + ".",
/* UseInputModulePath */ true));
break;
case options::OT_ASM_ONLY:
Conf.CGFileType = CGFT_AssemblyFile;
break;
}
if (!options::sample_profile.empty())
Conf.SampleProfile = options::sample_profile;
if (!options::cs_profile_path.empty())
Conf.CSIRProfile = options::cs_profile_path;
Conf.RunCSIRInstr = options::cs_pgo_gen;
Conf.DwoDir = options::dwo_dir;
// Set up optimization remarks handling.
Conf.RemarksFilename = options::RemarksFilename;
Conf.RemarksPasses = options::RemarksPasses;
Conf.RemarksWithHotness = options::RemarksWithHotness;
Conf.RemarksHotnessThreshold = options::RemarksHotnessThreshold;
Conf.RemarksFormat = options::RemarksFormat;
// Use new pass manager if set in driver
Conf.UseNewPM = options::new_pass_manager;
// Debug new pass manager if requested
Conf.DebugPassManager = options::debug_pass_manager;
Conf.HasWholeProgramVisibility = options::whole_program_visibility;
Conf.StatsFile = options::stats_file;
return std::make_unique<LTO>(std::move(Conf), Backend,
options::ParallelCodeGenParallelismLevel);
}
// Write empty files that may be expected by a distributed build
// system when invoked with thinlto_index_only. This is invoked when
// the linker has decided not to include the given module in the
// final link. Frequently the distributed build system will want to
// confirm that all expected outputs are created based on all of the
// modules provided to the linker.
// If SkipModule is true then .thinlto.bc should contain just
// SkipModuleByDistributedBackend flag which requests distributed backend
// to skip the compilation of the corresponding module and produce an empty
// object file.
static void writeEmptyDistributedBuildOutputs(const std::string &ModulePath,
const std::string &OldPrefix,
const std::string &NewPrefix,
bool SkipModule) {
std::string NewModulePath =
getThinLTOOutputFile(ModulePath, OldPrefix, NewPrefix);
std::error_code EC;
{
raw_fd_ostream OS(NewModulePath + ".thinlto.bc", EC,
sys::fs::OpenFlags::OF_None);
if (EC)
message(LDPL_FATAL, "Failed to write '%s': %s",
(NewModulePath + ".thinlto.bc").c_str(), EC.message().c_str());
if (SkipModule) {
ModuleSummaryIndex Index(/*HaveGVs*/ false);
Index.setSkipModuleByDistributedBackend();
WriteIndexToFile(Index, OS, nullptr);
}
}
if (options::thinlto_emit_imports_files) {
raw_fd_ostream OS(NewModulePath + ".imports", EC,
sys::fs::OpenFlags::OF_None);
if (EC)
message(LDPL_FATAL, "Failed to write '%s': %s",
(NewModulePath + ".imports").c_str(), EC.message().c_str());
}
}
// Creates and returns output stream with a list of object files for final
// linking of distributed ThinLTO.
static std::unique_ptr<raw_fd_ostream> CreateLinkedObjectsFile() {
if (options::thinlto_linked_objects_file.empty())
return nullptr;
assert(options::thinlto_index_only);
std::error_code EC;
auto LinkedObjectsFile = std::make_unique<raw_fd_ostream>(
options::thinlto_linked_objects_file, EC, sys::fs::OpenFlags::OF_None);
if (EC)
message(LDPL_FATAL, "Failed to create '%s': %s",
options::thinlto_linked_objects_file.c_str(), EC.message().c_str());
return LinkedObjectsFile;
}
/// Runs LTO and return a list of pairs <FileName, IsTemporary>.
static std::vector<std::pair<SmallString<128>, bool>> runLTO() {
// Map to own RAII objects that manage the file opening and releasing
// interfaces with gold. This is needed only for ThinLTO mode, since
// unlike regular LTO, where addModule will result in the opened file
// being merged into a new combined module, we need to keep these files open
// through Lto->run().
DenseMap<void *, std::unique_ptr<PluginInputFile>> HandleToInputFile;
// Owns string objects and tells if index file was already created.
StringMap<bool> ObjectToIndexFileState;
std::unique_ptr<raw_fd_ostream> LinkedObjects = CreateLinkedObjectsFile();
std::unique_ptr<LTO> Lto = createLTO(
[&ObjectToIndexFileState](const std::string &Identifier) {
ObjectToIndexFileState[Identifier] = true;
},
LinkedObjects.get());
std::string OldPrefix, NewPrefix;
if (options::thinlto_index_only)
getThinLTOOldAndNewPrefix(OldPrefix, NewPrefix);
std::string OldSuffix, NewSuffix;
getThinLTOOldAndNewSuffix(OldSuffix, NewSuffix);
for (claimed_file &F : Modules) {
if (options::thinlto && !HandleToInputFile.count(F.leader_handle))
HandleToInputFile.insert(std::make_pair(
F.leader_handle, std::make_unique<PluginInputFile>(F.handle)));
// In case we are thin linking with a minimized bitcode file, ensure
// the module paths encoded in the index reflect where the backends
// will locate the full bitcode files for compiling/importing.
std::string Identifier =
getThinLTOObjectFileName(F.name, OldSuffix, NewSuffix);
auto ObjFilename = ObjectToIndexFileState.insert({Identifier, false});
assert(ObjFilename.second);
if (const void *View = getSymbolsAndView(F))
addModule(*Lto, F, View, ObjFilename.first->first());
else if (options::thinlto_index_only) {
ObjFilename.first->second = true;
writeEmptyDistributedBuildOutputs(Identifier, OldPrefix, NewPrefix,
/* SkipModule */ true);
}
}
SmallString<128> Filename;
// Note that getOutputFileName will append a unique ID for each task
if (!options::obj_path.empty())
Filename = options::obj_path;
else if (options::TheOutputType == options::OT_SAVE_TEMPS)
Filename = output_name + ".lto.o";
else if (options::TheOutputType == options::OT_ASM_ONLY)
Filename = output_name;
bool SaveTemps = !Filename.empty();
size_t MaxTasks = Lto->getMaxTasks();
std::vector<std::pair<SmallString<128>, bool>> Files(MaxTasks);
auto AddStream =
[&](size_t Task) -> std::unique_ptr<lto::NativeObjectStream> {
Files[Task].second = !SaveTemps;
int FD = getOutputFileName(Filename, /* TempOutFile */ !SaveTemps,
Files[Task].first, Task);
return std::make_unique<lto::NativeObjectStream>(
std::make_unique<llvm::raw_fd_ostream>(FD, true));
};
auto AddBuffer = [&](size_t Task, std::unique_ptr<MemoryBuffer> MB) {
*AddStream(Task)->OS << MB->getBuffer();
};
NativeObjectCache Cache;
if (!options::cache_dir.empty())
Cache = check(localCache(options::cache_dir, AddBuffer));
check(Lto->run(AddStream, Cache));
// Write empty output files that may be expected by the distributed build
// system.
if (options::thinlto_index_only)
for (auto &Identifier : ObjectToIndexFileState)
if (!Identifier.getValue())
writeEmptyDistributedBuildOutputs(std::string(Identifier.getKey()),
OldPrefix, NewPrefix,
/* SkipModule */ false);
return Files;
}
/// 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 allSymbolsReadHook() {
if (Modules.empty())
return LDPS_OK;
if (unsigned NumOpts = options::extra.size())
cl::ParseCommandLineOptions(NumOpts, &options::extra[0]);
std::vector<std::pair<SmallString<128>, bool>> Files = runLTO();
if (options::TheOutputType == options::OT_DISABLE ||
options::TheOutputType == options::OT_BC_ONLY ||
options::TheOutputType == options::OT_ASM_ONLY)
return LDPS_OK;
if (options::thinlto_index_only) {
llvm_shutdown();
cleanup_hook();
exit(0);
}
for (const auto &F : Files)
if (!F.first.empty())
recordFile(std::string(F.first.str()), F.second);
if (!options::extra_library_path.empty() &&
set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK)
message(LDPL_FATAL, "Unable to set the extra library path.");
return LDPS_OK;
}
static ld_plugin_status all_symbols_read_hook(void) {
ld_plugin_status Ret = allSymbolsReadHook();
llvm_shutdown();
if (options::TheOutputType == options::OT_BC_ONLY ||
options::TheOutputType == options::OT_ASM_ONLY ||
options::TheOutputType == options::OT_DISABLE) {
if (options::TheOutputType == options::OT_DISABLE) {
// Remove the output file here since ld.bfd creates the output file
// early.
std::error_code EC = sys::fs::remove(output_name);
if (EC)
message(LDPL_ERROR, "Failed to delete '%s': %s", output_name.c_str(),
EC.message().c_str());
}
exit(0);
}
return Ret;
}
static ld_plugin_status cleanup_hook(void) {
for (std::string &Name : Cleanup) {
std::error_code EC = sys::fs::remove(Name);
if (EC)
message(LDPL_ERROR, "Failed to delete '%s': %s", Name.c_str(),
EC.message().c_str());
}
// Prune cache
if (!options::cache_dir.empty()) {
CachePruningPolicy policy = check(parseCachePruningPolicy(options::cache_policy));
pruneCache(options::cache_dir, policy);
}
return LDPS_OK;
}
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