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llvm-project/llvm/tools/gold/gold-plugin.cpp

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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/ADT/StringSet.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/CommandFlags.h"
#include "llvm/CodeGen/ParallelCG.h"
#include "llvm/Config/config.h" // plugin-api.h requires HAVE_STDINT_H
#include "llvm/IR/AutoUpgrade.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Verifier.h"
#include "llvm/Linker/IRMover.h"
#include "llvm/MC/SubtargetFeature.h"
#include "llvm/Object/IRObjectFile.h"
#include "llvm/Object/ModuleSummaryIndexObjectFile.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/ThreadPool.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/thread.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/IPO/PassManagerBuilder.h"
#include "llvm/Transforms/Utils/FunctionImportUtils.h"
#include "llvm/Transforms/Utils/GlobalStatus.h"
#include "llvm/Transforms/Utils/ValueMapper.h"
#include <list>
#include <plugin-api.h>
#include <system_error>
#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;
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;
std::vector<ld_plugin_symbol> syms;
};
/// 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 {
uint64_t CommonSize = 0;
unsigned CommonAlign = 0;
bool IsLinkonceOdr = true;
bool UnnamedAddr = true;
GlobalValue::VisibilityTypes Visibility = GlobalValue::DefaultVisibility;
bool CommonInternal = false;
bool UseCommon = false;
};
/// Class to own information used by a task or during its cleanup for a
/// ThinLTO backend instantiation.
class ThinLTOTaskInfo {
/// The input file holding the module bitcode read by the ThinLTO task.
PluginInputFile InputFile;
/// The output stream the task will codegen into.
std::unique_ptr<raw_fd_ostream> OS;
/// The file name corresponding to the output stream, used during cleanup.
std::string Filename;
/// Flag indicating whether the output file is a temp file that must be
/// added to the cleanup list during cleanup.
bool TempOutFile;
public:
ThinLTOTaskInfo(PluginInputFile InputFile, std::unique_ptr<raw_fd_ostream> OS,
std::string Filename, bool TempOutFile)
: InputFile(std::move(InputFile)), OS(std::move(OS)), Filename(Filename),
TempOutFile(TempOutFile) {}
/// Performs task related cleanup activities that must be done
/// single-threaded (i.e. call backs to gold).
void cleanup();
};
}
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 Reloc::Model RelocationModel = Reloc::Default;
static std::string output_name = "";
static std::list<claimed_file> Modules;
static StringMap<ResolutionInfo> ResInfo;
static std::vector<std::string> Cleanup;
static llvm::TargetOptions TargetOpts;
static std::string DefaultTriple = sys::getDefaultTargetTriple();
namespace options {
enum OutputType {
OT_NORMAL,
OT_DISABLE,
OT_BC_ONLY,
OT_SAVE_TEMPS
};
static bool generate_api_file = false;
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, code generation defaults to no parallelism, whereas
// ThinLTO uses the hardware_concurrency as the default.
static unsigned Parallelism = 0;
#ifdef NDEBUG
static bool DisableVerify = true;
static bool DiscardValueNames = true;
#else
static bool DisableVerify = false;
static bool DiscardValueNames = 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, exit after creating the combined index, the assuming is
// that the build system will launch the backend processes.
static bool thinlto_index_only = false;
// 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<const char *> extra;
static void process_plugin_option(const char *opt_)
{
if (opt_ == nullptr)
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") {
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.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 == "disable-verify") {
DisableVerify = true;
} else if (opt == "discard-value-names") {
DiscardValueNames = true;
} else if (opt == "no-discard-value-names") {
DiscardValueNames = false;
} 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
case LDPO_PIE: // position independent executable
RelocationModel = Reloc::PIC_;
break;
case LDPO_EXEC: // .exe
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 const GlobalObject *getBaseObject(const GlobalValue &GV) {
if (auto *GA = dyn_cast<GlobalAlias>(&GV))
return GA->getBaseObject();
return cast<GlobalObject>(&GV);
}
static bool shouldSkip(uint32_t Symflags) {
if (!(Symflags & object::BasicSymbolRef::SF_Global))
return true;
if (Symflags & object::BasicSymbolRef::SF_FormatSpecific)
return true;
return false;
}
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 diagnosticHandlerForContext(const DiagnosticInfo &DI,
void *Context) {
diagnosticHandler(DI);
}
static GlobalValue::VisibilityTypes
getMinVisibility(GlobalValue::VisibilityTypes A,
GlobalValue::VisibilityTypes B) {
if (A == GlobalValue::HiddenVisibility)
return A;
if (B == GlobalValue::HiddenVisibility)
return B;
if (A == GlobalValue::ProtectedVisibility)
return A;
return B;
}
/// 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) {
LLVMContext Context;
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();
}
Context.setDiagnosticHandler(diagnosticHandlerForContext);
ErrorOr<std::unique_ptr<object::IRObjectFile>> ObjOrErr =
object::IRObjectFile::create(BufferRef, Context);
std::error_code EC = ObjOrErr.getError();
if (EC == object::object_error::invalid_file_type ||
EC == object::object_error::bitcode_section_not_found)
return LDPS_OK;
*claimed = 1;
if (EC) {
message(LDPL_ERROR, "LLVM gold plugin has failed to create LTO module: %s",
EC.message().c_str());
return LDPS_ERR;
}
std::unique_ptr<object::IRObjectFile> Obj = std::move(*ObjOrErr);
Modules.resize(Modules.size() + 1);
claimed_file &cf = Modules.back();
cf.handle = file->handle;
// If we are doing ThinLTO compilation, don't need to process the symbols.
// Later we simply build a combined index file after all files are claimed.
if (options::thinlto && options::thinlto_index_only)
return LDPS_OK;
for (auto &Sym : Obj->symbols()) {
uint32_t Symflags = Sym.getFlags();
if (shouldSkip(Symflags))
continue;
cf.syms.push_back(ld_plugin_symbol());
ld_plugin_symbol &sym = cf.syms.back();
sym.version = nullptr;
SmallString<64> Name;
{
raw_svector_ostream OS(Name);
Sym.printName(OS);
}
sym.name = strdup(Name.c_str());
const GlobalValue *GV = Obj->getSymbolGV(Sym.getRawDataRefImpl());
ResolutionInfo &Res = ResInfo[sym.name];
sym.visibility = LDPV_DEFAULT;
if (GV) {
Res.UnnamedAddr &= GV->hasUnnamedAddr();
Res.IsLinkonceOdr &= GV->hasLinkOnceLinkage();
Res.Visibility = getMinVisibility(Res.Visibility, GV->getVisibility());
switch (GV->getVisibility()) {
case GlobalValue::DefaultVisibility:
sym.visibility = LDPV_DEFAULT;
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 (GV && GV->hasExternalWeakLinkage())
sym.def = LDPK_WEAKUNDEF;
} else {
sym.def = LDPK_DEF;
if (GV) {
assert(!GV->hasExternalWeakLinkage() &&
!GV->hasAvailableExternallyLinkage() && "Not a declaration!");
if (GV->hasCommonLinkage())
sym.def = LDPK_COMMON;
else if (GV->isWeakForLinker())
sym.def = LDPK_WEAKDEF;
}
}
sym.size = 0;
sym.comdat_key = nullptr;
if (GV) {
const GlobalObject *Base = getBaseObject(*GV);
if (!Base)
message(LDPL_FATAL, "Unable to determine comdat of alias!");
const Comdat *C = Base->getComdat();
if (C)
sym.comdat_key = strdup(C->getName().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 internalize(GlobalValue &GV) {
if (GV.isDeclarationForLinker())
return; // We get here if there is a matching asm definition.
if (!GV.hasLocalLinkage())
GV.setLinkage(GlobalValue::InternalLinkage);
}
static const char *getResolutionName(ld_plugin_symbol_resolution R) {
switch (R) {
case LDPR_UNKNOWN:
return "UNKNOWN";
case LDPR_UNDEF:
return "UNDEF";
case LDPR_PREVAILING_DEF:
return "PREVAILING_DEF";
case LDPR_PREVAILING_DEF_IRONLY:
return "PREVAILING_DEF_IRONLY";
case LDPR_PREEMPTED_REG:
return "PREEMPTED_REG";
case LDPR_PREEMPTED_IR:
return "PREEMPTED_IR";
case LDPR_RESOLVED_IR:
return "RESOLVED_IR";
case LDPR_RESOLVED_EXEC:
return "RESOLVED_EXEC";
case LDPR_RESOLVED_DYN:
return "RESOLVED_DYN";
case LDPR_PREVAILING_DEF_IRONLY_EXP:
return "PREVAILING_DEF_IRONLY_EXP";
}
llvm_unreachable("Unknown resolution");
}
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 std::unique_ptr<ModuleSummaryIndex>
getModuleSummaryIndexForFile(claimed_file &F, ld_plugin_input_file &Info) {
const void *View = getSymbolsAndView(F);
if (!View)
return nullptr;
MemoryBufferRef BufferRef(StringRef((const char *)View, Info.filesize),
Info.name);
// Don't bother trying to build an index if there is no summary information
// in this bitcode file.
if (!object::ModuleSummaryIndexObjectFile::hasGlobalValueSummaryInMemBuffer(
BufferRef, diagnosticHandler))
return std::unique_ptr<ModuleSummaryIndex>(nullptr);
ErrorOr<std::unique_ptr<object::ModuleSummaryIndexObjectFile>> ObjOrErr =
object::ModuleSummaryIndexObjectFile::create(BufferRef,
diagnosticHandler);
if (std::error_code EC = ObjOrErr.getError())
message(LDPL_FATAL,
"Could not read module summary index bitcode from file : %s",
EC.message().c_str());
object::ModuleSummaryIndexObjectFile &Obj = **ObjOrErr;
return Obj.takeIndex();
}
static std::unique_ptr<Module>
getModuleForFile(LLVMContext &Context, claimed_file &F, const void *View,
ld_plugin_input_file &Info, raw_fd_ostream *ApiFile,
StringSet<> &Internalize, StringSet<> &Maybe,
std::vector<GlobalValue *> &Keep,
StringMap<unsigned> &Realign) {
MemoryBufferRef BufferRef(StringRef((const char *)View, Info.filesize),
Info.name);
ErrorOr<std::unique_ptr<object::IRObjectFile>> ObjOrErr =
object::IRObjectFile::create(BufferRef, Context);
if (std::error_code EC = ObjOrErr.getError())
message(LDPL_FATAL, "Could not read bitcode from file : %s",
EC.message().c_str());
object::IRObjectFile &Obj = **ObjOrErr;
Module &M = Obj.getModule();
M.materializeMetadata();
UpgradeDebugInfo(M);
SmallPtrSet<GlobalValue *, 8> Used;
collectUsedGlobalVariables(M, Used, /*CompilerUsed*/ false);
unsigned SymNum = 0;
for (auto &ObjSym : Obj.symbols()) {
GlobalValue *GV = Obj.getSymbolGV(ObjSym.getRawDataRefImpl());
if (GV && GV->hasAppendingLinkage())
Keep.push_back(GV);
if (shouldSkip(ObjSym.getFlags()))
continue;
ld_plugin_symbol &Sym = F.syms[SymNum];
++SymNum;
ld_plugin_symbol_resolution Resolution =
(ld_plugin_symbol_resolution)Sym.resolution;
if (options::generate_api_file)
*ApiFile << Sym.name << ' ' << getResolutionName(Resolution) << '\n';
if (!GV) {
freeSymName(Sym);
continue; // Asm symbol.
}
ResolutionInfo &Res = ResInfo[Sym.name];
if (Resolution == LDPR_PREVAILING_DEF_IRONLY_EXP && !Res.IsLinkonceOdr)
Resolution = LDPR_PREVAILING_DEF;
// In ThinLTO mode change all prevailing resolutions to LDPR_PREVAILING_DEF.
// For ThinLTO the IR files are compiled through the backend independently,
// so we need to ensure that any prevailing linkonce copy will be emitted
// into the object file by making it weak. Additionally, we can skip the
// IRONLY handling for internalization, which isn't performed in ThinLTO
// mode currently anyway.
if (options::thinlto && (Resolution == LDPR_PREVAILING_DEF_IRONLY_EXP ||
Resolution == LDPR_PREVAILING_DEF_IRONLY))
Resolution = LDPR_PREVAILING_DEF;
GV->setUnnamedAddr(Res.UnnamedAddr);
GV->setVisibility(Res.Visibility);
// Override gold's resolution for common symbols. We want the largest
// one to win.
if (GV->hasCommonLinkage()) {
if (Resolution == LDPR_PREVAILING_DEF_IRONLY)
Res.CommonInternal = true;
if (Resolution == LDPR_PREVAILING_DEF_IRONLY ||
Resolution == LDPR_PREVAILING_DEF)
Res.UseCommon = true;
const DataLayout &DL = GV->getParent()->getDataLayout();
uint64_t Size = DL.getTypeAllocSize(GV->getType()->getElementType());
unsigned Align = GV->getAlignment();
if (Res.UseCommon && Size >= Res.CommonSize) {
// Take GV.
if (Res.CommonInternal)
Resolution = LDPR_PREVAILING_DEF_IRONLY;
else
Resolution = LDPR_PREVAILING_DEF;
cast<GlobalVariable>(GV)->setAlignment(
std::max(Res.CommonAlign, Align));
} else {
// Do not take GV, it's smaller than what we already have in the
// combined module.
Resolution = LDPR_PREEMPTED_IR;
if (Align > Res.CommonAlign)
// Need to raise the alignment though.
Realign[Sym.name] = Align;
}
Res.CommonSize = std::max(Res.CommonSize, Size);
Res.CommonAlign = std::max(Res.CommonAlign, Align);
}
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:
break;
case LDPR_UNDEF:
if (!GV->isDeclarationForLinker())
assert(GV->hasComdat());
break;
case LDPR_PREVAILING_DEF_IRONLY: {
Keep.push_back(GV);
// The IR linker has to be able to map this value to a declaration,
// so we can only internalize after linking.
if (!Used.count(GV))
Internalize.insert(GV->getName());
break;
}
case LDPR_PREVAILING_DEF:
Keep.push_back(GV);
// There is a non IR use, so we have to force optimizations to keep this.
switch (GV->getLinkage()) {
default:
break;
case GlobalValue::LinkOnceAnyLinkage:
GV->setLinkage(GlobalValue::WeakAnyLinkage);
break;
case GlobalValue::LinkOnceODRLinkage:
GV->setLinkage(GlobalValue::WeakODRLinkage);
break;
}
break;
case LDPR_PREVAILING_DEF_IRONLY_EXP: {
// We can only check for address uses after we merge the modules. The
// reason is that this GV might have a copy in another module
// and in that module the address might be significant, but that
// copy will be LDPR_PREEMPTED_IR.
Maybe.insert(GV->getName());
Keep.push_back(GV);
break;
}
}
freeSymName(Sym);
}
return Obj.takeModule();
}
static void saveBCFile(StringRef Path, Module &M) {
std::error_code EC;
raw_fd_ostream OS(Path, EC, sys::fs::OpenFlags::F_None);
if (EC)
message(LDPL_FATAL, "Failed to write the output file.");
WriteBitcodeToFile(&M, OS, /* ShouldPreserveUseListOrder */ false);
}
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());
}
void ThinLTOTaskInfo::cleanup() {
// Close the output file descriptor before we pass it to gold.
OS->close();
recordFile(Filename, TempOutFile);
}
namespace {
/// Class to manage optimization and code generation for a module, possibly
/// in a thread (ThinLTO).
class CodeGen {
/// The module for which this will generate code.
std::unique_ptr<llvm::Module> M;
/// The output stream to generate code into.
raw_fd_ostream *OS;
/// The task ID when this was invoked in a thread (ThinLTO).
int TaskID;
/// The module summary index for ThinLTO tasks.
const ModuleSummaryIndex *CombinedIndex;
/// The target machine for generating code for this module.
std::unique_ptr<TargetMachine> TM;
/// Filename to use as base when save-temps is enabled, used to get
/// a unique and identifiable save-temps output file for each ThinLTO backend.
std::string SaveTempsFilename;
public:
/// Constructor used by full LTO.
CodeGen(std::unique_ptr<llvm::Module> M)
: M(std::move(M)), OS(nullptr), TaskID(-1), CombinedIndex(nullptr) {
initTargetMachine();
}
/// Constructor used by ThinLTO.
CodeGen(std::unique_ptr<llvm::Module> M, raw_fd_ostream *OS, int TaskID,
const ModuleSummaryIndex *CombinedIndex, std::string Filename)
: M(std::move(M)), OS(OS), TaskID(TaskID), CombinedIndex(CombinedIndex),
SaveTempsFilename(Filename) {
assert(options::thinlto == !!CombinedIndex &&
"Expected module summary index iff performing ThinLTO");
initTargetMachine();
}
/// Invoke LTO passes and the code generator for the module.
void runAll();
/// Invoke the actual code generation to emit Module's object to file.
void runCodegenPasses();
private:
const Target *TheTarget;
std::string TripleStr;
std::string FeaturesString;
TargetOptions Options;
/// Create a target machine for the module. Must be unique for each
/// module/task.
void initTargetMachine();
std::unique_ptr<TargetMachine> createTargetMachine();
/// Run all LTO passes on the module.
void runLTOPasses();
/// Sets up output files necessary to perform optional multi-threaded
/// split code generation, and invokes the code generation implementation.
/// If BCFileName is not empty, saves bitcode for module partitions into
/// {BCFileName}0 .. {BCFileName}N.
void runSplitCodeGen(const SmallString<128> &BCFilename);
};
}
static SubtargetFeatures getFeatures(Triple &TheTriple) {
SubtargetFeatures Features;
Features.getDefaultSubtargetFeatures(TheTriple);
for (const std::string &A : MAttrs)
Features.AddFeature(A);
return Features;
}
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");
}
void CodeGen::initTargetMachine() {
TripleStr = M->getTargetTriple();
Triple TheTriple(TripleStr);
std::string ErrMsg;
TheTarget = TargetRegistry::lookupTarget(TripleStr, ErrMsg);
if (!TheTarget)
message(LDPL_FATAL, "Target not found: %s", ErrMsg.c_str());
SubtargetFeatures Features = getFeatures(TheTriple);
FeaturesString = Features.getString();
Options = InitTargetOptionsFromCodeGenFlags();
TM = createTargetMachine();
}
std::unique_ptr<TargetMachine> CodeGen::createTargetMachine() {
CodeGenOpt::Level CGOptLevel = getCGOptLevel();
return std::unique_ptr<TargetMachine>(TheTarget->createTargetMachine(
TripleStr, options::mcpu, FeaturesString, Options, RelocationModel,
CodeModel::Default, CGOptLevel));
}
void CodeGen::runLTOPasses() {
M->setDataLayout(TM->createDataLayout());
legacy::PassManager passes;
passes.add(createTargetTransformInfoWrapperPass(TM->getTargetIRAnalysis()));
PassManagerBuilder PMB;
PMB.LibraryInfo = new TargetLibraryInfoImpl(Triple(TM->getTargetTriple()));
PMB.Inliner = createFunctionInliningPass();
// Unconditionally verify input since it is not verified before this
// point and has unknown origin.
PMB.VerifyInput = true;
PMB.VerifyOutput = !options::DisableVerify;
PMB.LoopVectorize = true;
PMB.SLPVectorize = true;
PMB.OptLevel = options::OptLevel;
PMB.ModuleSummary = CombinedIndex;
PMB.populateLTOPassManager(passes);
passes.run(*M);
}
/// Open a file and return the new file descriptor given a base input
/// file 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 openOutputFile(SmallString<128> InFilename, bool TempOutFile,
SmallString<128> &NewFilename, int TaskID = -1) {
int FD;
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::F_None);
if (EC)
message(LDPL_FATAL, "Could not open file: %s", EC.message().c_str());
}
return FD;
}
void CodeGen::runCodegenPasses() {
assert(OS && "Output stream must be set before emitting to file");
legacy::PassManager CodeGenPasses;
if (TM->addPassesToEmitFile(CodeGenPasses, *OS,
TargetMachine::CGFT_ObjectFile))
report_fatal_error("Failed to setup codegen");
CodeGenPasses.run(*M);
}
void CodeGen::runSplitCodeGen(const SmallString<128> &BCFilename) {
SmallString<128> Filename;
// Note that openOutputFile 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";
// Note that the default parallelism is 1 instead of the
// hardware_concurrency, as there are behavioral differences between
// parallelism levels (e.g. symbol ordering will be different, and some uses
// of inline asm currently have issues with parallelism >1).
unsigned int MaxThreads = options::Parallelism ? options::Parallelism : 1;
std::vector<SmallString<128>> Filenames(MaxThreads);
std::vector<SmallString<128>> BCFilenames(MaxThreads);
bool TempOutFile = Filename.empty();
{
// Open a file descriptor for each backend task. This is done in a block
// so that the output file descriptors are closed before gold opens them.
std::list<llvm::raw_fd_ostream> OSs;
std::vector<llvm::raw_pwrite_stream *> OSPtrs(MaxThreads);
for (unsigned I = 0; I != MaxThreads; ++I) {
int FD = openOutputFile(Filename, TempOutFile, Filenames[I],
// Only append ID if there are multiple tasks.
MaxThreads > 1 ? I : -1);
OSs.emplace_back(FD, true);
OSPtrs[I] = &OSs.back();
}
std::list<llvm::raw_fd_ostream> BCOSs;
std::vector<llvm::raw_pwrite_stream *> BCOSPtrs;
if (!BCFilename.empty() && MaxThreads > 1) {
for (unsigned I = 0; I != MaxThreads; ++I) {
int FD = openOutputFile(BCFilename, false, BCFilenames[I], I);
BCOSs.emplace_back(FD, true);
BCOSPtrs.push_back(&BCOSs.back());
}
}
// Run backend tasks.
splitCodeGen(std::move(M), OSPtrs, BCOSPtrs,
[&]() { return createTargetMachine(); });
}
for (auto &Filename : Filenames)
recordFile(Filename.c_str(), TempOutFile);
}
void CodeGen::runAll() {
runLTOPasses();
SmallString<128> OptFilename;
if (options::TheOutputType == options::OT_SAVE_TEMPS) {
OptFilename = output_name;
// If the CodeGen client provided a filename, use it. Always expect
// a provided filename if we are in a task (i.e. ThinLTO backend).
assert(!SaveTempsFilename.empty() || TaskID == -1);
if (!SaveTempsFilename.empty())
OptFilename = SaveTempsFilename;
OptFilename += ".opt.bc";
saveBCFile(OptFilename, *M);
}
// If we are already in a thread (i.e. ThinLTO), just perform
// codegen passes directly.
if (TaskID >= 0)
runCodegenPasses();
// Otherwise attempt split code gen.
else
runSplitCodeGen(OptFilename);
}
/// Links the module in \p View from file \p F into the combined module
/// saved in the IRMover \p L. Returns true on error, false on success.
static bool linkInModule(LLVMContext &Context, IRMover &L, claimed_file &F,
const void *View, ld_plugin_input_file &File,
raw_fd_ostream *ApiFile, StringSet<> &Internalize,
StringSet<> &Maybe) {
std::vector<GlobalValue *> Keep;
StringMap<unsigned> Realign;
std::unique_ptr<Module> M = getModuleForFile(
Context, F, View, File, ApiFile, Internalize, Maybe, Keep, Realign);
if (!M.get())
return false;
if (!options::triple.empty())
M->setTargetTriple(options::triple.c_str());
else if (M->getTargetTriple().empty()) {
M->setTargetTriple(DefaultTriple);
}
if (!L.move(std::move(M), Keep, [](GlobalValue &, IRMover::ValueAdder) {}))
return false;
for (const auto &I : Realign) {
GlobalValue *Dst = L.getModule().getNamedValue(I.first());
if (!Dst)
continue;
cast<GlobalVariable>(Dst)->setAlignment(I.second);
}
return true;
}
/// Perform the ThinLTO backend on a single module, invoking the LTO and codegen
/// pipelines.
static void thinLTOBackendTask(claimed_file &F, const void *View,
ld_plugin_input_file &File,
raw_fd_ostream *ApiFile,
const ModuleSummaryIndex &CombinedIndex,
raw_fd_ostream *OS, unsigned TaskID) {
// Need to use a separate context for each task
LLVMContext Context;
Context.setDiscardValueNames(options::DiscardValueNames);
Context.enableDebugTypeODRUniquing(); // Merge debug info types.
Context.setDiagnosticHandler(diagnosticHandlerForContext, nullptr, true);
std::unique_ptr<llvm::Module> NewModule(new llvm::Module(File.name, Context));
IRMover L(*NewModule.get());
StringSet<> Dummy;
if (linkInModule(Context, L, F, View, File, ApiFile, Dummy, Dummy))
message(LDPL_FATAL, "Failed to rename module for ThinLTO");
if (renameModuleForThinLTO(*NewModule, CombinedIndex))
message(LDPL_FATAL, "Failed to rename module for ThinLTO");
CodeGen codeGen(std::move(NewModule), OS, TaskID, &CombinedIndex, File.name);
codeGen.runAll();
}
/// Launch each module's backend pipeline in a separate task in a thread pool.
static void thinLTOBackends(raw_fd_ostream *ApiFile,
const ModuleSummaryIndex &CombinedIndex) {
unsigned TaskCount = 0;
std::vector<ThinLTOTaskInfo> Tasks;
Tasks.reserve(Modules.size());
unsigned int MaxThreads = options::Parallelism
? options::Parallelism
: thread::hardware_concurrency();
// Create ThreadPool in nested scope so that threads will be joined
// on destruction.
{
ThreadPool ThinLTOThreadPool(MaxThreads);
for (claimed_file &F : Modules) {
// Do all the gold callbacks in the main thread, since gold is not thread
// safe by default.
PluginInputFile InputFile(F.handle);
const void *View = getSymbolsAndView(F);
if (!View)
continue;
SmallString<128> Filename;
if (!options::obj_path.empty())
// Note that openOutputFile will append a unique ID for each task
Filename = options::obj_path;
else if (options::TheOutputType == options::OT_SAVE_TEMPS) {
// Use the input file name so that we get a unique and identifiable
// output file for each ThinLTO backend task.
Filename = InputFile.file().name;
Filename += ".thinlto.o";
}
bool TempOutFile = Filename.empty();
SmallString<128> NewFilename;
int FD = openOutputFile(Filename, TempOutFile, NewFilename,
// Only append the TaskID if we will use the
// non-unique obj_path.
!options::obj_path.empty() ? TaskCount : -1);
TaskCount++;
std::unique_ptr<raw_fd_ostream> OS =
llvm::make_unique<raw_fd_ostream>(FD, true);
// Enqueue the task
ThinLTOThreadPool.async(thinLTOBackendTask, std::ref(F), View,
std::ref(InputFile.file()), ApiFile,
std::ref(CombinedIndex), OS.get(), TaskCount);
// Record the information needed by the task or during its cleanup
// to a ThinLTOTaskInfo instance. For information needed by the task
// the unique_ptr ownership is transferred to the ThinLTOTaskInfo.
Tasks.emplace_back(std::move(InputFile), std::move(OS),
NewFilename.c_str(), TempOutFile);
}
}
for (auto &Task : Tasks)
Task.cleanup();
}
/// 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(raw_fd_ostream *ApiFile) {
if (Modules.empty())
return LDPS_OK;
if (unsigned NumOpts = options::extra.size())
cl::ParseCommandLineOptions(NumOpts, &options::extra[0]);
// If we are doing ThinLTO compilation, simply build the combined
// module index/summary and emit it. We don't need to parse the modules
// and link them in this case.
if (options::thinlto) {
ModuleSummaryIndex CombinedIndex;
uint64_t NextModuleId = 0;
for (claimed_file &F : Modules) {
PluginInputFile InputFile(F.handle);
std::unique_ptr<ModuleSummaryIndex> Index =
getModuleSummaryIndexForFile(F, InputFile.file());
// Skip files without a module summary.
if (Index)
CombinedIndex.mergeFrom(std::move(Index), ++NextModuleId);
}
std::error_code EC;
raw_fd_ostream OS(output_name + ".thinlto.bc", EC,
sys::fs::OpenFlags::F_None);
if (EC)
message(LDPL_FATAL, "Unable to open %s.thinlto.bc for writing: %s",
output_name.data(), EC.message().c_str());
WriteIndexToFile(CombinedIndex, OS);
OS.close();
if (options::thinlto_index_only) {
cleanup_hook();
exit(0);
}
thinLTOBackends(ApiFile, CombinedIndex);
return LDPS_OK;
}
LLVMContext Context;
Context.setDiscardValueNames(options::DiscardValueNames);
Context.enableDebugTypeODRUniquing(); // Merge debug info types.
Context.setDiagnosticHandler(diagnosticHandlerForContext, nullptr, true);
std::unique_ptr<Module> Combined(new Module("ld-temp.o", Context));
IRMover L(*Combined);
StringSet<> Internalize;
StringSet<> Maybe;
for (claimed_file &F : Modules) {
PluginInputFile InputFile(F.handle);
const void *View = getSymbolsAndView(F);
if (!View)
continue;
if (linkInModule(Context, L, F, View, InputFile.file(), ApiFile,
Internalize, Maybe))
message(LDPL_FATAL, "Failed to link module");
}
for (const auto &Name : Internalize) {
GlobalValue *GV = Combined->getNamedValue(Name.first());
if (GV)
internalize(*GV);
}
for (const auto &Name : Maybe) {
GlobalValue *GV = Combined->getNamedValue(Name.first());
if (!GV)
continue;
GV->setLinkage(GlobalValue::LinkOnceODRLinkage);
if (canBeOmittedFromSymbolTable(GV))
internalize(*GV);
}
if (options::TheOutputType == options::OT_DISABLE)
return LDPS_OK;
if (options::TheOutputType != options::OT_NORMAL) {
std::string path;
if (options::TheOutputType == options::OT_BC_ONLY)
path = output_name;
else
path = output_name + ".bc";
saveBCFile(path, *Combined);
if (options::TheOutputType == options::OT_BC_ONLY)
return LDPS_OK;
}
CodeGen codeGen(std::move(Combined));
codeGen.runAll();
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;
if (!options::generate_api_file) {
Ret = allSymbolsReadHook(nullptr);
} else {
std::error_code EC;
raw_fd_ostream ApiFile("apifile.txt", EC, sys::fs::F_None);
if (EC)
message(LDPL_FATAL, "Unable to open apifile.txt for writing: %s",
EC.message().c_str());
Ret = allSymbolsReadHook(&ApiFile);
}
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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