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llvm-mirror/tools/gold/gold-plugin.cpp
Rafael Espindola f8f8e59cdd Make the LTO comdat api more symbol table friendly. 
In an IR symbol table I would expect the comdats to be represented as:

- A table of strings, one for each comdat name.
- Each symbol has an optional index into that table.

The natural api for accessing that would be

InputFile:
ArrayRef<StringRef> getComdatTable() const;

Symbol:
int getComdatIndex() const;

This patch implements an API as close to that as possible.  The
implementation on top of the current IRObjectFile is a bit hackish,
but should map just fine over a symbol table and is very convenient to
use.

llvm-svn: 285061
2016-10-25 12:02:03 +00:00

890 lines
30 KiB
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//===-- 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/Bitcode/ReaderWriter.h"
#include "llvm/CodeGen/CommandFlags.h"
#include "llvm/Config/config.h" // plugin-api.h requires HAVE_STDINT_H
#include "llvm/IR/Constants.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/LTO/Caching.h"
#include "llvm/LTO/LTO.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/TargetSelect.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
using namespace llvm;
using namespace lto;
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;
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 = llvm::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;
};
}
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 Optional<Reloc::Model> RelocationModel;
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;
static llvm::TargetOptions TargetOpts;
static size_t MaxTasks;
namespace options {
enum OutputType {
OT_NORMAL,
OT_DISABLE,
OT_BC_ONLY,
OT_SAVE_TEMPS
};
static OutputType TheOutputType = OT_NORMAL;
static unsigned OptLevel = 2;
// Default parallelism of 0 used to indicate that user did not specify.
// Actual parallelism default value depends on implementation.
// Currently only affects ThinLTO, where the default is
// llvm::heavyweight_hardware_concurrency.
static unsigned Parallelism = 0;
// 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;
// Optional path to a directory for caching ThinLTO objects.
static std::string cache_dir;
// 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;
static void process_plugin_option(const char *opt_)
{
if (opt_ == nullptr)
return;
llvm::StringRef opt = opt_;
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") {
TheOutputType = OT_BC_ONLY;
} else if (opt == "save-temps") {
TheOutputType = OT_SAVE_TEMPS;
} else if (opt == "disable-output") {
TheOutputType = OT_DISABLE;
} else if (opt == "thinlto") {
thinlto = true;
} else if (opt == "thinlto-index-only") {
thinlto_index_only = true;
} else if (opt.startswith("thinlto-index-only=")) {
thinlto_index_only = true;
thinlto_linked_objects_file = opt.substr(strlen("thinlto-index-only="));
} else if (opt == "thinlto-emit-imports-files") {
thinlto_emit_imports_files = true;
} else if (opt.startswith("thinlto-prefix-replace=")) {
thinlto_prefix_replace = opt.substr(strlen("thinlto-prefix-replace="));
if (thinlto_prefix_replace.find(";") == std::string::npos)
message(LDPL_FATAL, "thinlto-prefix-replace expects 'old;new' format");
} else if (opt.startswith("cache-dir=")) {
cache_dir = opt.substr(strlen("cache-dir="));
} 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.startswith("jobs=")) {
if (StringRef(opt_ + 5).getAsInteger(10, Parallelism))
message(LDPL_FATAL, "Invalid parallelism level: %s", opt_ + 5);
} else if (opt.startswith("lto-partitions=")) {
if (opt.substr(strlen("lto-partitions="))
.getAsInteger(10, ParallelCodeGenParallelismLevel))
message(LDPL_FATAL, "Invalid codegen partition level: %s", opt_ + 5);
} else if (opt == "disable-verify") {
DisableVerify = true;
} 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
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;
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) {
if (const auto *BDI = dyn_cast<BitcodeDiagnosticInfo>(&DI)) {
std::error_code EC = BDI->getError();
if (EC == BitcodeError::InvalidBitcodeSignature)
return;
}
std::string ErrStorage;
{
raw_string_ostream OS(ErrStorage);
DiagnosticPrinterRawOStream DP(OS);
DI.print(DP);
}
ld_plugin_level Level;
switch (DI.getSeverity()) {
case DS_Error:
message(LDPL_FATAL, "LLVM gold plugin has failed to create LTO module: %s",
ErrStorage.c_str());
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) {
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(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_ERROR,
"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.resize(Modules.size() + 1);
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()) {
uint32_t Symflags = Sym.getFlags();
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 (Symflags & object::BasicSymbolRef::SF_Undefined) {
sym.def = LDPK_UNDEF;
if (Symflags & object::BasicSymbolRef::SF_Weak)
sym.def = LDPK_WEAKUNDEF;
} else if (Symflags & object::BasicSymbolRef::SF_Common)
sym.def = LDPK_COMMON;
else if (Symflags & object::BasicSymbolRef::SF_Weak)
sym.def = LDPK_WEAKDEF;
else
sym.def = LDPK_DEF;
sym.size = 0;
sym.comdat_key = nullptr;
int CI = check(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;
}
}
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;
}
static void addModule(LTO &Lto, claimed_file &F, const void *View) {
MemoryBufferRef BufferRef(StringRef((const char *)View, F.filesize), F.name);
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::vector<SymbolResolution> Resols(F.syms.size());
for (ld_plugin_symbol &Sym : F.syms) {
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_RESOLVED_DYN:
case LDPR_PREEMPTED_IR:
case LDPR_PREEMPTED_REG:
case LDPR_UNDEF:
break;
case LDPR_PREVAILING_DEF_IRONLY:
R.Prevailing = true;
break;
case LDPR_PREVAILING_DEF:
R.Prevailing = true;
R.VisibleToRegularObj = true;
break;
case LDPR_PREVAILING_DEF_IRONLY_EXP:
R.Prevailing = true;
if (!Res.CanOmitFromDynSym)
R.VisibleToRegularObj = true;
break;
}
if (Resolution != LDPR_RESOLVED_DYN && Resolution != LDPR_UNDEF &&
(IsExecutable || !Res.DefaultVisibility))
R.FinalDefinitionInLinkageUnit = true;
freeSymName(Sym);
}
check(Lto.add(std::move(*ObjOrErr), Resols),
std::string("Failed to link module ") + F.name);
}
static void recordFile(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.c_str());
}
/// 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 void getOutputFileName(SmallString<128> InFilename, bool TempOutFile,
SmallString<128> &NewFilename, int TaskID = -1) {
if (TempOutFile) {
std::error_code EC =
sys::fs::createTemporaryFile("lto-llvm", "o", 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);
}
}
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);
std::pair<StringRef, StringRef> Split = PrefixReplace.split(";");
OldPrefix = Split.first.str();
NewPrefix = Split.second.str();
}
static std::unique_ptr<LTO> createLTO() {
Config Conf;
ThinBackend Backend;
Conf.CPU = options::mcpu;
Conf.Options = InitTargetOptionsFromCodeGenFlags();
// 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;
Conf.MAttrs = MAttrs;
Conf.RelocModel = *RelocationModel;
Conf.CGOptLevel = getCGOptLevel();
Conf.DisableVerify = options::DisableVerify;
Conf.OptLevel = options::OptLevel;
if (options::Parallelism)
Backend = createInProcessThinBackend(options::Parallelism);
if (options::thinlto_index_only) {
std::string OldPrefix, NewPrefix;
getThinLTOOldAndNewPrefix(OldPrefix, NewPrefix);
Backend = createWriteIndexesThinBackend(
OldPrefix, NewPrefix, options::thinlto_emit_imports_files,
options::thinlto_linked_objects_file);
}
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;
raw_fd_ostream OS(output_name, EC, sys::fs::OpenFlags::F_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;
}
return llvm::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.
static void writeEmptyDistributedBuildOutputs(std::string &ModulePath,
std::string &OldPrefix,
std::string &NewPrefix) {
std::string NewModulePath =
getThinLTOOutputFile(ModulePath, OldPrefix, NewPrefix);
std::error_code EC;
{
raw_fd_ostream OS(NewModulePath + ".thinlto.bc", EC,
sys::fs::OpenFlags::F_None);
if (EC)
message(LDPL_FATAL, "Failed to write '%s': %s",
(NewModulePath + ".thinlto.bc").c_str(), EC.message().c_str());
}
if (options::thinlto_emit_imports_files) {
raw_fd_ostream OS(NewModulePath + ".imports", EC,
sys::fs::OpenFlags::F_None);
if (EC)
message(LDPL_FATAL, "Failed to write '%s': %s",
(NewModulePath + ".imports").c_str(), EC.message().c_str());
}
}
/// 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]);
// 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;
std::unique_ptr<LTO> Lto = createLTO();
std::string OldPrefix, NewPrefix;
if (options::thinlto_index_only)
getThinLTOOldAndNewPrefix(OldPrefix, NewPrefix);
for (claimed_file &F : Modules) {
if (options::thinlto && !HandleToInputFile.count(F.leader_handle))
HandleToInputFile.insert(std::make_pair(
F.leader_handle, llvm::make_unique<PluginInputFile>(F.handle)));
const void *View = getSymbolsAndView(F);
if (!View) {
if (options::thinlto_index_only)
// Write empty output files that may be expected by the distributed
// build system.
writeEmptyDistributedBuildOutputs(F.name, OldPrefix, NewPrefix);
continue;
}
addModule(*Lto, F, View);
}
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 + ".o";
bool SaveTemps = !Filename.empty();
MaxTasks = Lto->getMaxTasks();
std::vector<uintptr_t> IsTemporary(MaxTasks);
std::vector<SmallString<128>> Filenames(MaxTasks);
auto AddStream =
[&](size_t Task) -> std::unique_ptr<lto::NativeObjectStream> {
IsTemporary[Task] = !SaveTemps;
getOutputFileName(Filename, /*TempOutFile=*/!SaveTemps, Filenames[Task],
MaxTasks > 1 ? Task : -1);
int FD;
std::error_code EC =
sys::fs::openFileForWrite(Filenames[Task], FD, sys::fs::F_None);
if (EC)
message(LDPL_FATAL, "Could not open file: %s", EC.message().c_str());
return llvm::make_unique<lto::NativeObjectStream>(
llvm::make_unique<llvm::raw_fd_ostream>(FD, true));
};
auto AddFile = [&](size_t Task, StringRef Path) { Filenames[Task] = Path; };
NativeObjectCache Cache;
if (!options::cache_dir.empty())
Cache = localCache(options::cache_dir, AddFile);
check(Lto->run(AddStream, Cache));
if (options::TheOutputType == options::OT_DISABLE ||
options::TheOutputType == options::OT_BC_ONLY)
return LDPS_OK;
if (options::thinlto_index_only) {
cleanup_hook();
exit(0);
}
for (unsigned I = 0; I != MaxTasks; ++I)
if (!Filenames[I].empty())
recordFile(Filenames[I].str(), IsTemporary[I]);
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_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());
}
return LDPS_OK;
}
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