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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/Config/config.h" // plugin-api.h requires HAVE_STDINT_H
#include "llvm/ADT/DenseSet.h"
#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/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/Linker.h"
#include "llvm/MC/SubtargetFeature.h"
#include "llvm/Object/IRObjectFile.h"
#include "llvm/Object/FunctionIndexObjectFile.h"
#include "llvm/Support/raw_ostream.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/Transforms/IPO.h"
#include "llvm/Transforms/IPO/PassManagerBuilder.h"
#include "llvm/Transforms/Utils/GlobalStatus.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
#include "llvm/Transforms/Utils/ValueMapper.h"
#include <list>
#include <plugin-api.h>
#include <system_error>
#include <vector>
#ifndef LDPO_PIE
// FIXME: remove this declaration when we stop maintaining Ubuntu Quantal and
// Precise and Debian Wheezy (binutils 2.23 is required)
# define LDPO_PIE 3
#endif
using namespace llvm;
namespace {
struct claimed_file {
void *handle;
std::vector<ld_plugin_symbol> syms;
};
}
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_get_input_file get_input_file = nullptr;
static ld_plugin_release_input_file release_input_file = nullptr;
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 ld_plugin_message message = discard_message;
static Reloc::Model RelocationModel = Reloc::Default;
static std::string output_name = "";
static std::list<claimed_file> Modules;
static std::vector<std::string> Cleanup;
static llvm::TargetOptions TargetOpts;
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;
static unsigned Parallelism = 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;
// 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.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 {
// 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) {
switch (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:
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, "relesase_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, void *Context) {
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());
llvm_unreachable("Fatal doesn't return.");
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());
}
/// 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(diagnosticHandler);
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)
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());
sym.visibility = LDPV_DEFAULT;
if (GV) {
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());
else if (Base->hasWeakLinkage() || Base->hasLinkOnceLinkage())
sym.comdat_key = strdup(sym.name);
}
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 keepGlobalValue(GlobalValue &GV,
std::vector<GlobalAlias *> &KeptAliases) {
assert(!GV.hasLocalLinkage());
if (auto *GA = dyn_cast<GlobalAlias>(&GV))
KeptAliases.push_back(GA);
switch (GV.getLinkage()) {
default:
break;
case GlobalValue::LinkOnceAnyLinkage:
GV.setLinkage(GlobalValue::WeakAnyLinkage);
break;
case GlobalValue::LinkOnceODRLinkage:
GV.setLinkage(GlobalValue::WeakODRLinkage);
break;
}
assert(!GV.isDiscardableIfUnused());
}
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 void drop(GlobalValue &GV) {
if (auto *F = dyn_cast<Function>(&GV)) {
F->deleteBody();
F->setComdat(nullptr); // Should deleteBody do this?
return;
}
if (auto *Var = dyn_cast<GlobalVariable>(&GV)) {
Var->setInitializer(nullptr);
Var->setLinkage(
GlobalValue::ExternalLinkage); // Should setInitializer do this?
Var->setComdat(nullptr); // and this?
return;
}
auto &Alias = cast<GlobalAlias>(GV);
Module &M = *Alias.getParent();
PointerType &Ty = *cast<PointerType>(Alias.getType());
GlobalValue::LinkageTypes L = Alias.getLinkage();
auto *Var =
new GlobalVariable(M, Ty.getElementType(), /*isConstant*/ false, L,
/*Initializer*/ nullptr);
Var->takeName(&Alias);
Alias.replaceAllUsesWith(Var);
Alias.eraseFromParent();
}
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");
}
namespace {
class LocalValueMaterializer final : public ValueMaterializer {
DenseSet<GlobalValue *> &Dropped;
DenseMap<GlobalObject *, GlobalObject *> LocalVersions;
public:
LocalValueMaterializer(DenseSet<GlobalValue *> &Dropped) : Dropped(Dropped) {}
Value *materializeValueFor(Value *V) override;
};
}
Value *LocalValueMaterializer::materializeValueFor(Value *V) {
auto *GO = dyn_cast<GlobalObject>(V);
if (!GO)
return nullptr;
auto I = LocalVersions.find(GO);
if (I != LocalVersions.end())
return I->second;
if (!Dropped.count(GO))
return nullptr;
Module &M = *GO->getParent();
GlobalValue::LinkageTypes L = GO->getLinkage();
GlobalObject *Declaration;
if (auto *F = dyn_cast<Function>(GO)) {
Declaration = Function::Create(F->getFunctionType(), L, "", &M);
} else {
auto *Var = cast<GlobalVariable>(GO);
Declaration = new GlobalVariable(M, Var->getType()->getElementType(),
Var->isConstant(), L,
/*Initializer*/ nullptr);
}
Declaration->takeName(GO);
Declaration->copyAttributesFrom(GO);
GO->setLinkage(GlobalValue::InternalLinkage);
GO->setName(Declaration->getName());
Dropped.erase(GO);
GO->replaceAllUsesWith(Declaration);
LocalVersions[Declaration] = GO;
return GO;
}
static Constant *mapConstantToLocalCopy(Constant *C, ValueToValueMapTy &VM,
LocalValueMaterializer *Materializer) {
return MapValue(C, VM, RF_IgnoreMissingEntries, nullptr, Materializer);
}
static void freeSymName(ld_plugin_symbol &Sym) {
free(Sym.name);
free(Sym.comdat_key);
Sym.name = nullptr;
Sym.comdat_key = nullptr;
}
static std::unique_ptr<FunctionInfoIndex>
getFunctionIndexForFile(LLVMContext &Context, claimed_file &F,
ld_plugin_input_file &Info) {
if (get_symbols(F.handle, F.syms.size(), &F.syms[0]) != 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");
MemoryBufferRef BufferRef(StringRef((const char *)View, Info.filesize),
Info.name);
ErrorOr<std::unique_ptr<object::FunctionIndexObjectFile>> ObjOrErr =
object::FunctionIndexObjectFile::create(BufferRef, Context);
if (std::error_code EC = ObjOrErr.getError())
message(LDPL_FATAL, "Could not read function index bitcode from file : %s",
EC.message().c_str());
object::FunctionIndexObjectFile &Obj = **ObjOrErr;
return Obj.takeIndex();
}
static std::unique_ptr<Module>
getModuleForFile(LLVMContext &Context, claimed_file &F,
ld_plugin_input_file &Info, raw_fd_ostream *ApiFile,
StringSet<> &Internalize, StringSet<> &Maybe) {
if (get_symbols(F.handle, F.syms.size(), F.syms.data()) != 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");
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);
DenseSet<GlobalValue *> Drop;
std::vector<GlobalAlias *> KeptAliases;
unsigned SymNum = 0;
for (auto &ObjSym : Obj.symbols()) {
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';
GlobalValue *GV = Obj.getSymbolGV(ObjSym.getRawDataRefImpl());
if (!GV) {
freeSymName(Sym);
continue; // Asm symbol.
}
if (Resolution != LDPR_PREVAILING_DEF_IRONLY && GV->hasCommonLinkage()) {
// Common linkage is special. There is no single symbol that wins the
// resolution. Instead we have to collect the maximum alignment and size.
// The IR linker does that for us if we just pass it every common GV.
// We still have to keep track of LDPR_PREVAILING_DEF_IRONLY so we
// internalize once the IR linker has done its job.
freeSymName(Sym);
continue;
}
switch (Resolution) {
case LDPR_UNKNOWN:
llvm_unreachable("Unexpected resolution");
case LDPR_RESOLVED_IR:
case LDPR_RESOLVED_EXEC:
case LDPR_RESOLVED_DYN:
assert(GV->isDeclarationForLinker());
break;
case LDPR_UNDEF:
if (!GV->isDeclarationForLinker()) {
assert(GV->hasComdat());
Drop.insert(GV);
}
break;
case LDPR_PREVAILING_DEF_IRONLY: {
keepGlobalValue(*GV, KeptAliases);
if (!Used.count(GV)) {
// Since we use the regular lib/Linker, we cannot just internalize GV
// now or it will not be copied to the merged module. Instead we force
// it to be copied and then internalize it.
Internalize.insert(GV->getName());
}
break;
}
case LDPR_PREVAILING_DEF:
keepGlobalValue(*GV, KeptAliases);
break;
case LDPR_PREEMPTED_IR:
// Gold might have selected a linkonce_odr and preempted a weak_odr.
// In that case we have to make sure we don't end up internalizing it.
if (!GV->isDiscardableIfUnused())
Maybe.erase(GV->getName());
// fall-through
case LDPR_PREEMPTED_REG:
Drop.insert(GV);
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.
if (GV->hasLinkOnceODRLinkage())
Maybe.insert(GV->getName());
keepGlobalValue(*GV, KeptAliases);
break;
}
}
freeSymName(Sym);
}
ValueToValueMapTy VM;
LocalValueMaterializer Materializer(Drop);
for (GlobalAlias *GA : KeptAliases) {
// Gold told us to keep GA. It is possible that a GV usied in the aliasee
// expression is being dropped. If that is the case, that GV must be copied.
Constant *Aliasee = GA->getAliasee();
Constant *Replacement = mapConstantToLocalCopy(Aliasee, VM, &Materializer);
GA->setAliasee(Replacement);
}
for (auto *GV : Drop)
drop(*GV);
return Obj.takeModule();
}
static void runLTOPasses(Module &M, TargetMachine &TM) {
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.populateLTOPassManager(passes);
passes.run(M);
}
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 */ true);
}
static void codegen(std::unique_ptr<Module> M) {
const std::string &TripleStr = M->getTargetTriple();
Triple TheTriple(TripleStr);
std::string ErrMsg;
const Target *TheTarget = TargetRegistry::lookupTarget(TripleStr, ErrMsg);
if (!TheTarget)
message(LDPL_FATAL, "Target not found: %s", ErrMsg.c_str());
if (unsigned NumOpts = options::extra.size())
cl::ParseCommandLineOptions(NumOpts, &options::extra[0]);
SubtargetFeatures Features;
Features.getDefaultSubtargetFeatures(TheTriple);
for (const std::string &A : MAttrs)
Features.AddFeature(A);
TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
CodeGenOpt::Level CGOptLevel;
switch (options::OptLevel) {
case 0:
CGOptLevel = CodeGenOpt::None;
break;
case 1:
CGOptLevel = CodeGenOpt::Less;
break;
case 2:
CGOptLevel = CodeGenOpt::Default;
break;
case 3:
CGOptLevel = CodeGenOpt::Aggressive;
break;
}
std::unique_ptr<TargetMachine> TM(TheTarget->createTargetMachine(
TripleStr, options::mcpu, Features.getString(), Options, RelocationModel,
CodeModel::Default, CGOptLevel));
runLTOPasses(*M, *TM);
if (options::TheOutputType == options::OT_SAVE_TEMPS)
saveBCFile(output_name + ".opt.bc", *M);
SmallString<128> Filename;
if (!options::obj_path.empty())
Filename = options::obj_path;
else if (options::TheOutputType == options::OT_SAVE_TEMPS)
Filename = output_name + ".o";
std::vector<SmallString<128>> Filenames(options::Parallelism);
bool TempOutFile = Filename.empty();
{
// Open a file descriptor for each backend thread. 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(options::Parallelism);
for (unsigned I = 0; I != options::Parallelism; ++I) {
int FD;
if (TempOutFile) {
std::error_code EC =
sys::fs::createTemporaryFile("lto-llvm", "o", FD, Filenames[I]);
if (EC)
message(LDPL_FATAL, "Could not create temporary file: %s",
EC.message().c_str());
} else {
Filenames[I] = Filename;
if (options::Parallelism != 1)
Filenames[I] += utostr(I);
std::error_code EC =
sys::fs::openFileForWrite(Filenames[I], FD, sys::fs::F_None);
if (EC)
message(LDPL_FATAL, "Could not open file: %s", EC.message().c_str());
}
OSs.emplace_back(FD, true);
OSPtrs[I] = &OSs.back();
}
// Run backend threads.
splitCodeGen(std::move(M), OSPtrs, options::mcpu, Features.getString(),
Options, RelocationModel, CodeModel::Default, CGOptLevel);
}
for (auto &Filename : Filenames) {
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());
}
}
/// 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;
LLVMContext Context;
Context.setDiagnosticHandler(diagnosticHandler, nullptr, true);
// If we are doing ThinLTO compilation, simply build the combined
// function index/summary and emit it. We don't need to parse the modules
// and link them in this case.
if (options::thinlto) {
FunctionInfoIndex CombinedIndex;
uint64_t NextModuleId = 0;
for (claimed_file &F : Modules) {
ld_plugin_input_file File;
if (get_input_file(F.handle, &File) != LDPS_OK)
message(LDPL_FATAL, "Failed to get file information");
std::unique_ptr<FunctionInfoIndex> Index =
getFunctionIndexForFile(Context, F, File);
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());
WriteFunctionSummaryToFile(CombinedIndex, OS);
OS.close();
cleanup_hook();
exit(0);
}
std::unique_ptr<Module> Combined(new Module("ld-temp.o", Context));
Linker L(Combined.get());
std::string DefaultTriple = sys::getDefaultTargetTriple();
StringSet<> Internalize;
StringSet<> Maybe;
for (claimed_file &F : Modules) {
ld_plugin_input_file File;
if (get_input_file(F.handle, &File) != LDPS_OK)
message(LDPL_FATAL, "Failed to get file information");
std::unique_ptr<Module> M =
getModuleForFile(Context, F, File, ApiFile, Internalize, Maybe);
if (!options::triple.empty())
M->setTargetTriple(options::triple.c_str());
else if (M->getTargetTriple().empty()) {
M->setTargetTriple(DefaultTriple);
}
if (L.linkInModule(M.get()))
message(LDPL_FATAL, "Failed to link module");
if (release_input_file(F.handle) != LDPS_OK)
message(LDPL_FATAL, "Failed to release file information");
}
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, *L.getModule());
if (options::TheOutputType == options::OT_BC_ONLY)
return LDPS_OK;
}
codegen(std::move(Combined));
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.
sys::fs::remove(output_name);
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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