Google Git Google Git
Sign in
llvm/llvm-project/a257e2aa4eb47ad340915136228cd28d918e8dc2/./llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
blob: 211d13c19e459054b548318b3eedd0fb79fad3f7 [file]
//===- llvm/CodeGen/TargetLoweringObjectFileImpl.cpp - Object File Info ---===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements classes used to handle lowerings specific to common
// object file formats.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/BinaryFormat/COFF.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/BinaryFormat/GOFF.h"
#include "llvm/BinaryFormat/MachO.h"
#include "llvm/BinaryFormat/Wasm.h"
#include "llvm/CodeGen/BasicBlockSectionUtils.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineModuleInfoImpls.h"
#include "llvm/IR/Comdat.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalObject.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCAsmInfoDarwin.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCGOFFAttributes.h"
#include "llvm/MC/MCSectionCOFF.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCSectionGOFF.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCSectionWasm.h"
#include "llvm/MC/MCSectionXCOFF.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCSymbolELF.h"
#include "llvm/MC/MCSymbolGOFF.h"
#include "llvm/MC/MCValue.h"
#include "llvm/MC/SectionKind.h"
#include "llvm/ProfileData/InstrProf.h"
#include "llvm/Support/Base64.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/TargetParser/Triple.h"
#include <cassert>
#include <string>
using namespace llvm;
using namespace dwarf;
static cl::opt<bool> JumpTableInFunctionSection(
"jumptable-in-function-section", cl::Hidden, cl::init(false),
cl::desc("Putting Jump Table in function section"));
static void GetObjCImageInfo(Module &M, unsigned &Version, unsigned &Flags,
StringRef &Section) {
SmallVector<Module::ModuleFlagEntry, 8> ModuleFlags;
M.getModuleFlagsMetadata(ModuleFlags);
for (const auto &MFE: ModuleFlags) {
// Ignore flags with 'Require' behaviour.
if (MFE.Behavior == Module::Require)
continue;
StringRef Key = MFE.Key->getString();
if (Key == "Objective-C Image Info Version") {
Version = mdconst::extract<ConstantInt>(MFE.Val)->getZExtValue();
} else if (Key == "Objective-C Garbage Collection" ||
Key == "Objective-C GC Only" ||
Key == "Objective-C Is Simulated" ||
Key == "Objective-C Class Properties" ||
Key == "Objective-C Image Swift Version") {
Flags |= mdconst::extract<ConstantInt>(MFE.Val)->getZExtValue();
} else if (Key == "Objective-C Image Info Section") {
Section = cast<MDString>(MFE.Val)->getString();
}
// Backend generates L_OBJC_IMAGE_INFO from Swift ABI version + major + minor +
// "Objective-C Garbage Collection".
else if (Key == "Swift ABI Version") {
Flags |= (mdconst::extract<ConstantInt>(MFE.Val)->getZExtValue()) << 8;
} else if (Key == "Swift Major Version") {
Flags |= (mdconst::extract<ConstantInt>(MFE.Val)->getZExtValue()) << 24;
} else if (Key == "Swift Minor Version") {
Flags |= (mdconst::extract<ConstantInt>(MFE.Val)->getZExtValue()) << 16;
}
}
}
//===----------------------------------------------------------------------===//
// ELF
//===----------------------------------------------------------------------===//
void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
const TargetMachine &TgtM) {
TargetLoweringObjectFile::Initialize(Ctx, TgtM);
CodeModel::Model CM = TgtM.getCodeModel();
InitializeELF(TgtM.Options.UseInitArray);
switch (TgtM.getTargetTriple().getArch()) {
case Triple::arm:
case Triple::armeb:
case Triple::thumb:
case Triple::thumbeb:
if (Ctx.getAsmInfo().getExceptionHandlingType() == ExceptionHandling::ARM)
break;
// Fallthrough if not using EHABI
[[fallthrough]];
case Triple::ppc:
case Triple::ppcle:
case Triple::x86:
PersonalityEncoding = isPositionIndependent()
? dwarf::DW_EH_PE_indirect |
dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata4
: dwarf::DW_EH_PE_absptr;
LSDAEncoding = isPositionIndependent()
? dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
: dwarf::DW_EH_PE_absptr;
TTypeEncoding = isPositionIndependent()
? dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata4
: dwarf::DW_EH_PE_absptr;
break;
case Triple::x86_64:
if (isPositionIndependent()) {
PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
((CM == CodeModel::Small || CM == CodeModel::Medium)
? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
LSDAEncoding = dwarf::DW_EH_PE_pcrel |
(CM == CodeModel::Small
? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
((CM == CodeModel::Small || CM == CodeModel::Medium)
? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
} else {
PersonalityEncoding =
(CM == CodeModel::Small || CM == CodeModel::Medium)
? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
LSDAEncoding = (CM == CodeModel::Small)
? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
TTypeEncoding = (CM == CodeModel::Small)
? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
}
break;
case Triple::hexagon:
PersonalityEncoding = dwarf::DW_EH_PE_absptr;
LSDAEncoding = dwarf::DW_EH_PE_absptr;
TTypeEncoding = dwarf::DW_EH_PE_absptr;
if (isPositionIndependent()) {
PersonalityEncoding |= dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel;
LSDAEncoding |= dwarf::DW_EH_PE_pcrel;
TTypeEncoding |= dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel;
}
break;
case Triple::aarch64:
case Triple::aarch64_be:
case Triple::aarch64_32:
// The small model guarantees static code/data size < 4GB, but not where it
// will be in memory. Most of these could end up >2GB away so even a signed
// pc-relative 32-bit address is insufficient, theoretically.
//
// Use DW_EH_PE_indirect even for -fno-pic to avoid copy relocations.
LSDAEncoding = dwarf::DW_EH_PE_pcrel |
(TgtM.getTargetTriple().getEnvironment() == Triple::GNUILP32
? dwarf::DW_EH_PE_sdata4
: dwarf::DW_EH_PE_sdata8);
PersonalityEncoding = LSDAEncoding | dwarf::DW_EH_PE_indirect;
TTypeEncoding = LSDAEncoding | dwarf::DW_EH_PE_indirect;
break;
case Triple::lanai:
LSDAEncoding = dwarf::DW_EH_PE_absptr;
PersonalityEncoding = dwarf::DW_EH_PE_absptr;
TTypeEncoding = dwarf::DW_EH_PE_absptr;
break;
case Triple::mips:
case Triple::mipsel:
case Triple::mips64:
case Triple::mips64el:
// MIPS uses indirect pointer to refer personality functions and types, so
// that the eh_frame section can be read-only. DW.ref.personality will be
// generated for relocation.
PersonalityEncoding = dwarf::DW_EH_PE_indirect;
// FIXME: The N64 ABI probably ought to use DW_EH_PE_sdata8 but we can't
// identify N64 from just a triple.
TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata4;
// FreeBSD must be explicit about the data size and using pcrel since it's
// assembler/linker won't do the automatic conversion that the Linux tools
// do.
if (isPositionIndependent() || TgtM.getTargetTriple().isOSFreeBSD()) {
PersonalityEncoding |= dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
}
break;
case Triple::ppc64:
case Triple::ppc64le:
PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_udata8;
LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8;
TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_udata8;
break;
case Triple::sparcel:
case Triple::sparc:
if (isPositionIndependent()) {
LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata4;
TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata4;
} else {
LSDAEncoding = dwarf::DW_EH_PE_absptr;
PersonalityEncoding = dwarf::DW_EH_PE_absptr;
TTypeEncoding = dwarf::DW_EH_PE_absptr;
}
CallSiteEncoding = dwarf::DW_EH_PE_udata4;
break;
case Triple::riscv32:
case Triple::riscv64:
case Triple::riscv32be:
case Triple::riscv64be:
LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata4;
TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata4;
CallSiteEncoding = dwarf::DW_EH_PE_udata4;
break;
case Triple::sparcv9:
LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
if (isPositionIndependent()) {
PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata4;
TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata4;
} else {
PersonalityEncoding = dwarf::DW_EH_PE_absptr;
TTypeEncoding = dwarf::DW_EH_PE_absptr;
}
break;
case Triple::systemz:
// All currently-defined code models guarantee that 4-byte PC-relative
// values will be in range.
if (isPositionIndependent()) {
PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata4;
LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata4;
} else {
PersonalityEncoding = dwarf::DW_EH_PE_absptr;
LSDAEncoding = dwarf::DW_EH_PE_absptr;
TTypeEncoding = dwarf::DW_EH_PE_absptr;
}
break;
case Triple::loongarch32:
case Triple::loongarch64:
LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata4;
TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata4;
break;
default:
break;
}
}
void TargetLoweringObjectFileELF::getModuleMetadata(Module &M) {
SmallVector<GlobalValue *, 4> Vec;
collectUsedGlobalVariables(M, Vec, false);
for (GlobalValue *GV : Vec)
if (auto *GO = dyn_cast<GlobalObject>(GV))
Used.insert(GO);
}
void TargetLoweringObjectFileELF::emitModuleMetadata(MCStreamer &Streamer,
Module &M) const {
auto &C = getContext();
emitLinkerDirectives(Streamer, M);
if (NamedMDNode *DependentLibraries = M.getNamedMetadata("llvm.dependent-libraries")) {
auto *S = C.getELFSection(".deplibs", ELF::SHT_LLVM_DEPENDENT_LIBRARIES,
ELF::SHF_MERGE | ELF::SHF_STRINGS, 1);
Streamer.switchSection(S);
for (const auto *Operand : DependentLibraries->operands()) {
Streamer.emitBytes(
cast<MDString>(cast<MDNode>(Operand)->getOperand(0))->getString());
Streamer.emitInt8(0);
}
}
emitPseudoProbeDescMetadata(Streamer, M);
if (NamedMDNode *LLVMStats = M.getNamedMetadata("llvm.stats")) {
// Emit the metadata for llvm statistics into .llvm_stats section, which is
// formatted as a list of key/value pair, the value is base64 encoded.
auto *S = C.getObjectFileInfo()->getLLVMStatsSection();
Streamer.switchSection(S);
for (const auto *Operand : LLVMStats->operands()) {
const auto *MD = cast<MDNode>(Operand);
assert(MD->getNumOperands() % 2 == 0 &&
("Operand num should be even for a list of key/value pair"));
for (size_t I = 0; I < MD->getNumOperands(); I += 2) {
// Encode the key string size.
auto *Key = cast<MDString>(MD->getOperand(I));
Streamer.emitULEB128IntValue(Key->getString().size());
Streamer.emitBytes(Key->getString());
// Encode the value into a Base64 string.
std::string Value = encodeBase64(
Twine(mdconst::dyn_extract<ConstantInt>(MD->getOperand(I + 1))
->getZExtValue())
.str());
Streamer.emitULEB128IntValue(Value.size());
Streamer.emitBytes(Value);
}
}
}
unsigned Version = 0;
unsigned Flags = 0;
StringRef Section;
GetObjCImageInfo(M, Version, Flags, Section);
if (!Section.empty()) {
auto *S = C.getELFSection(Section, ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
Streamer.switchSection(S);
Streamer.emitLabel(C.getOrCreateSymbol(StringRef("OBJC_IMAGE_INFO")));
Streamer.emitInt32(Version);
Streamer.emitInt32(Flags);
Streamer.addBlankLine();
}
emitCGProfileMetadata(Streamer, M);
}
void TargetLoweringObjectFileELF::emitLinkerDirectives(MCStreamer &Streamer,
Module &M) const {
auto &C = getContext();
if (NamedMDNode *LinkerOptions = M.getNamedMetadata("llvm.linker.options")) {
auto *S = C.getELFSection(".linker-options", ELF::SHT_LLVM_LINKER_OPTIONS,
ELF::SHF_EXCLUDE);
Streamer.switchSection(S);
for (const auto *Operand : LinkerOptions->operands()) {
if (cast<MDNode>(Operand)->getNumOperands() != 2)
report_fatal_error("invalid llvm.linker.options");
for (const auto &Option : cast<MDNode>(Operand)->operands()) {
Streamer.emitBytes(cast<MDString>(Option)->getString());
Streamer.emitInt8(0);
}
}
}
}
MCSymbol *TargetLoweringObjectFileELF::getCFIPersonalitySymbol(
const GlobalValue *GV, const TargetMachine &TM,
MachineModuleInfo *MMI) const {
unsigned Encoding = getPersonalityEncoding();
if ((Encoding & 0x80) == DW_EH_PE_indirect)
return getContext().getOrCreateSymbol(StringRef("DW.ref.") +
TM.getSymbol(GV)->getName());
if ((Encoding & 0x70) == DW_EH_PE_absptr)
return TM.getSymbol(GV);
report_fatal_error("We do not support this DWARF encoding yet!");
}
void TargetLoweringObjectFileELF::emitPersonalityValue(
MCStreamer &Streamer, const DataLayout &DL, const MCSymbol *Sym,
const MachineModuleInfo *MMI) const {
SmallString<64> NameData("DW.ref.");
NameData += Sym->getName();
auto *Label =
static_cast<MCSymbolELF *>(getContext().getOrCreateSymbol(NameData));
Streamer.emitSymbolAttribute(Label, MCSA_Hidden);
Streamer.emitSymbolAttribute(Label, MCSA_Weak);
unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_GROUP;
MCSection *Sec = getContext().getELFNamedSection(".data", Label->getName(),
ELF::SHT_PROGBITS, Flags, 0);
unsigned Size = DL.getPointerSize();
Streamer.switchSection(Sec);
Streamer.emitValueToAlignment(DL.getPointerABIAlignment(0));
Streamer.emitSymbolAttribute(Label, MCSA_ELF_TypeObject);
const MCExpr *E = MCConstantExpr::create(Size, getContext());
Streamer.emitELFSize(Label, E);
Streamer.emitLabel(Label);
emitPersonalityValueImpl(Streamer, DL, Sym, MMI);
}
void TargetLoweringObjectFileELF::emitPersonalityValueImpl(
MCStreamer &Streamer, const DataLayout &DL, const MCSymbol *Sym,
const MachineModuleInfo *MMI) const {
Streamer.emitSymbolValue(Sym, DL.getPointerSize());
}
const MCExpr *TargetLoweringObjectFileELF::getTTypeGlobalReference(
const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM,
MachineModuleInfo *MMI, MCStreamer &Streamer) const {
if (Encoding & DW_EH_PE_indirect) {
MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, ".DW.stub", TM);
// Add information about the stub reference to ELFMMI so that the stub
// gets emitted by the asmprinter.
MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
if (!StubSym.getPointer()) {
MCSymbol *Sym = TM.getSymbol(GV);
StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
}
return TargetLoweringObjectFile::
getTTypeReference(MCSymbolRefExpr::create(SSym, getContext()),
Encoding & ~DW_EH_PE_indirect, Streamer);
}
return TargetLoweringObjectFile::getTTypeGlobalReference(GV, Encoding, TM,
MMI, Streamer);
}
static SectionKind getELFKindForNamedSection(StringRef Name, SectionKind K) {
// N.B.: The defaults used in here are not the same ones used in MC.
// We follow gcc, MC follows gas. For example, given ".section .eh_frame",
// both gas and MC will produce a section with no flags. Given
// section(".eh_frame") gcc will produce:
//
// .section .eh_frame,"a",@progbits
if (Name == getInstrProfSectionName(IPSK_covmap, Triple::ELF,
/*AddSegmentInfo=*/false) ||
Name == getInstrProfSectionName(IPSK_covfun, Triple::ELF,
/*AddSegmentInfo=*/false) ||
Name == getInstrProfSectionName(IPSK_covdata, Triple::ELF,
/*AddSegmentInfo=*/false) ||
Name == getInstrProfSectionName(IPSK_covname, Triple::ELF,
/*AddSegmentInfo=*/false) ||
Name == ".llvmbc" || Name == ".llvmcmd")
return SectionKind::getMetadata();
if (!Name.starts_with(".")) return K;
// Default implementation based on some magic section names.
if (Name == ".bss" || Name.starts_with(".bss.") ||
Name.starts_with(".gnu.linkonce.b.") ||
Name.starts_with(".llvm.linkonce.b.") || Name == ".sbss" ||
Name.starts_with(".sbss.") || Name.starts_with(".gnu.linkonce.sb.") ||
Name.starts_with(".llvm.linkonce.sb."))
return SectionKind::getBSS();
if (Name == ".tdata" || Name.starts_with(".tdata.") ||
Name.starts_with(".gnu.linkonce.td.") ||
Name.starts_with(".llvm.linkonce.td."))
return SectionKind::getThreadData();
if (Name == ".tbss" || Name.starts_with(".tbss.") ||
Name.starts_with(".gnu.linkonce.tb.") ||
Name.starts_with(".llvm.linkonce.tb."))
return SectionKind::getThreadBSS();
return K;
}
static bool hasPrefix(StringRef SectionName, StringRef Prefix) {
return SectionName.consume_front(Prefix) &&
(SectionName.empty() || SectionName[0] == '.');
}
static unsigned getELFSectionType(StringRef Name, SectionKind K) {
// Use SHT_NOTE for section whose name starts with ".note" to allow
// emitting ELF notes from C variable declaration.
// See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77609
if (Name.starts_with(".note"))
return ELF::SHT_NOTE;
if (hasPrefix(Name, ".init_array"))
return ELF::SHT_INIT_ARRAY;
if (hasPrefix(Name, ".fini_array"))
return ELF::SHT_FINI_ARRAY;
if (hasPrefix(Name, ".preinit_array"))
return ELF::SHT_PREINIT_ARRAY;
if (hasPrefix(Name, ".llvm.offloading"))
return ELF::SHT_LLVM_OFFLOADING;
if (Name == ".llvm.lto")
return ELF::SHT_LLVM_LTO;
if (K.isBSS() || K.isThreadBSS())
return ELF::SHT_NOBITS;
return ELF::SHT_PROGBITS;
}
static unsigned getELFSectionFlags(SectionKind K, const Triple &T) {
unsigned Flags = 0;
if (!K.isMetadata() && !K.isExclude())
Flags |= ELF::SHF_ALLOC;
if (K.isExclude())
Flags |= ELF::SHF_EXCLUDE;
if (K.isText())
Flags |= ELF::SHF_EXECINSTR;
if (K.isExecuteOnly()) {
if (T.isAArch64())
Flags |= ELF::SHF_AARCH64_PURECODE;
else if (T.isARM() || T.isThumb())
Flags |= ELF::SHF_ARM_PURECODE;
}
if (K.isWriteable())
Flags |= ELF::SHF_WRITE;
if (K.isThreadLocal())
Flags |= ELF::SHF_TLS;
if (K.isMergeableCString() || K.isMergeableConst())
Flags |= ELF::SHF_MERGE;
if (K.isMergeableCString())
Flags |= ELF::SHF_STRINGS;
return Flags;
}
static const Comdat *getELFComdat(const GlobalValue *GV) {
const Comdat *C = GV->getComdat();
if (!C)
return nullptr;
if (C->getSelectionKind() != Comdat::Any &&
C->getSelectionKind() != Comdat::NoDeduplicate)
report_fatal_error("ELF COMDATs only support SelectionKind::Any and "
"SelectionKind::NoDeduplicate, '" +
C->getName() + "' cannot be lowered.");
return C;
}
static const MCSymbolELF *getLinkedToSymbol(const GlobalObject *GO,
const TargetMachine &TM) {
MDNode *MD = GO->getMetadata(LLVMContext::MD_associated);
if (!MD)
return nullptr;
auto *VM = cast<ValueAsMetadata>(MD->getOperand(0).get());
auto *OtherGV = dyn_cast<GlobalValue>(VM->getValue());
return OtherGV ? static_cast<const MCSymbolELF *>(TM.getSymbol(OtherGV))
: nullptr;
}
static unsigned getEntrySizeForKind(SectionKind Kind) {
if (Kind.isMergeable1ByteCString())
return 1;
else if (Kind.isMergeable2ByteCString())
return 2;
else if (Kind.isMergeable4ByteCString())
return 4;
else if (Kind.isMergeableConst4())
return 4;
else if (Kind.isMergeableConst8())
return 8;
else if (Kind.isMergeableConst16())
return 16;
else if (Kind.isMergeableConst32())
return 32;
else {
// We shouldn't have mergeable C strings or mergeable constants that we
// didn't handle above.
assert(!Kind.isMergeableCString() && "unknown string width");
assert(!Kind.isMergeableConst() && "unknown data width");
return 0;
}
}
/// Return the section prefix name used by options FunctionsSections and
/// DataSections.
static StringRef getSectionPrefixForGlobal(SectionKind Kind, bool IsLarge) {
if (Kind.isText())
return IsLarge ? ".ltext" : ".text";
if (Kind.isReadOnly())
return IsLarge ? ".lrodata" : ".rodata";
if (Kind.isBSS())
return IsLarge ? ".lbss" : ".bss";
if (Kind.isThreadData())
return ".tdata";
if (Kind.isThreadBSS())
return ".tbss";
if (Kind.isData())
return IsLarge ? ".ldata" : ".data";
if (Kind.isReadOnlyWithRel())
return IsLarge ? ".ldata.rel.ro" : ".data.rel.ro";
llvm_unreachable("Unknown section kind");
}
static SmallString<128>
getELFSectionNameForGlobal(const GlobalObject *GO, SectionKind Kind,
Mangler &Mang, const TargetMachine &TM,
bool UniqueSectionName,
const MachineJumpTableEntry *JTE) {
SmallString<128> Name =
getSectionPrefixForGlobal(Kind, TM.isLargeGlobalValue(GO));
unsigned EntrySize = getEntrySizeForKind(Kind);
if (Kind.isMergeableCString()) {
// We also need alignment here.
// FIXME: this is getting the alignment of the character, not the
// alignment of the global!
Align Alignment = GO->getDataLayout().getPreferredAlign(
cast<GlobalVariable>(GO));
Name += ".str";
Name += utostr(EntrySize);
Name += ".";
Name += utostr(Alignment.value());
} else if (Kind.isMergeableConst()) {
Name += ".cst";
Name += utostr(EntrySize);
}
bool HasPrefix = false;
if (const auto *F = dyn_cast<Function>(GO)) {
// Jump table hotness takes precedence over its enclosing function's hotness
// if it's known. The function's section prefix is used if jump table entry
// hotness is unknown.
if (JTE && JTE->Hotness != MachineFunctionDataHotness::Unknown) {
if (JTE->Hotness == MachineFunctionDataHotness::Hot) {
raw_svector_ostream(Name) << ".hot";
} else {
assert(JTE->Hotness == MachineFunctionDataHotness::Cold &&
"Hotness must be cold");
raw_svector_ostream(Name) << ".unlikely";
}
HasPrefix = true;
} else if (std::optional<StringRef> Prefix = F->getSectionPrefix()) {
raw_svector_ostream(Name) << '.' << *Prefix;
HasPrefix = true;
}
} else if (const auto *GV = dyn_cast<GlobalVariable>(GO)) {
if (std::optional<StringRef> Prefix = GV->getSectionPrefix()) {
raw_svector_ostream(Name) << '.' << *Prefix;
HasPrefix = true;
}
}
if (UniqueSectionName) {
Name.push_back('.');
TM.getNameWithPrefix(Name, GO, Mang, /*MayAlwaysUsePrivate*/true);
} else if (HasPrefix)
// For distinguishing between .text.${text-section-prefix}. (with trailing
// dot) and .text.${function-name}
Name.push_back('.');
return Name;
}
namespace {
class LoweringDiagnosticInfo : public DiagnosticInfo {
const Twine &Msg;
public:
LoweringDiagnosticInfo(const Twine &DiagMsg LLVM_LIFETIME_BOUND,
DiagnosticSeverity Severity = DS_Error)
: DiagnosticInfo(DK_Lowering, Severity), Msg(DiagMsg) {}
void print(DiagnosticPrinter &DP) const override { DP << Msg; }
};
}
/// Calculate an appropriate unique ID for a section, and update Flags,
/// EntrySize and NextUniqueID where appropriate.
static unsigned
calcUniqueIDUpdateFlagsAndSize(const GlobalObject *GO, StringRef SectionName,
SectionKind Kind, const TargetMachine &TM,
MCContext &Ctx, Mangler &Mang, unsigned &Flags,
unsigned &EntrySize, unsigned &NextUniqueID,
const bool Retain, const bool ForceUnique) {
// Increment uniqueID if we are forced to emit a unique section.
// This works perfectly fine with section attribute or pragma section as the
// sections with the same name are grouped together by the assembler.
if (ForceUnique)
return NextUniqueID++;
// A section can have at most one associated section. Put each global with
// MD_associated in a unique section.
const bool Associated = GO->getMetadata(LLVMContext::MD_associated);
if (Associated) {
Flags |= ELF::SHF_LINK_ORDER;
return NextUniqueID++;
}
if (Retain) {
if (TM.getTargetTriple().isOSSolaris())
Flags |= ELF::SHF_SUNW_NODISCARD;
else if (Ctx.getAsmInfo().useIntegratedAssembler() ||
Ctx.getAsmInfo().binutilsIsAtLeast(2, 36))
Flags |= ELF::SHF_GNU_RETAIN;
return NextUniqueID++;
}
// If two symbols with differing sizes end up in the same mergeable section
// that section can be assigned an incorrect entry size. To avoid this we
// usually put symbols of the same size into distinct mergeable sections with
// the same name. Doing so relies on the ",unique ," assembly feature. This
// feature is not available until binutils version 2.35
// (https://sourceware.org/bugzilla/show_bug.cgi?id=25380).
const bool SupportsUnique = Ctx.getAsmInfo().useIntegratedAssembler() ||
Ctx.getAsmInfo().binutilsIsAtLeast(2, 35);
if (!SupportsUnique) {
Flags &= ~ELF::SHF_MERGE;
EntrySize = 0;
return MCSection::NonUniqueID;
}
const bool SymbolMergeable = Flags & ELF::SHF_MERGE;
const bool SeenSectionNameBefore =
Ctx.isELFGenericMergeableSection(SectionName);
// If this is the first occurrence of this section name, treat it as the
// generic section
if (!SymbolMergeable && !SeenSectionNameBefore) {
if (TM.getSeparateNamedSections())
return NextUniqueID++;
else
return MCSection::NonUniqueID;
}
// Symbols must be placed into sections with compatible entry sizes. Generate
// unique sections for symbols that have not been assigned to compatible
// sections.
const auto PreviousID =
Ctx.getELFUniqueIDForEntsize(SectionName, Flags, EntrySize);
if (PreviousID &&
(!TM.getSeparateNamedSections() || *PreviousID == MCSection::NonUniqueID))
return *PreviousID;
// If the user has specified the same section name as would be created
// implicitly for this symbol e.g. .rodata.str1.1, then we don't need
// to unique the section as the entry size for this symbol will be
// compatible with implicitly created sections.
SmallString<128> ImplicitSectionNameStem =
getELFSectionNameForGlobal(GO, Kind, Mang, TM, false, /*MJTE=*/nullptr);
if (SymbolMergeable &&
Ctx.isELFImplicitMergeableSectionNamePrefix(SectionName) &&
SectionName.starts_with(ImplicitSectionNameStem))
return MCSection::NonUniqueID;
// We have seen this section name before, but with different flags or entity
// size. Create a new unique ID.
return NextUniqueID++;
}
static std::tuple<StringRef, bool, unsigned, unsigned, unsigned>
getGlobalObjectInfo(const GlobalObject *GO, const TargetMachine &TM,
StringRef SectionName, SectionKind Kind) {
StringRef Group = "";
bool IsComdat = false;
unsigned Flags = 0;
if (const Comdat *C = getELFComdat(GO)) {
Flags |= ELF::SHF_GROUP;
Group = C->getName();
IsComdat = C->getSelectionKind() == Comdat::Any;
}
if (TM.isLargeGlobalValue(GO))
Flags |= ELF::SHF_X86_64_LARGE;
unsigned Type, EntrySize;
if (MDNode *MD = GO->getMetadata(LLVMContext::MD_elf_section_properties)) {
Type = cast<ConstantAsMetadata>(MD->getOperand(0))
->getValue()
->getUniqueInteger()
.getZExtValue();
EntrySize = cast<ConstantAsMetadata>(MD->getOperand(1))
->getValue()
->getUniqueInteger()
.getZExtValue();
} else {
Type = getELFSectionType(SectionName, Kind);
EntrySize = getEntrySizeForKind(Kind);
}
return {Group, IsComdat, Flags, Type, EntrySize};
}
static StringRef handlePragmaClangSection(const GlobalObject *GO,
SectionKind Kind) {
// Check if '#pragma clang section' name is applicable.
// Note that pragma directive overrides -ffunction-section, -fdata-section
// and so section name is exactly as user specified and not uniqued.
const GlobalVariable *GV = dyn_cast<GlobalVariable>(GO);
if (GV && GV->hasImplicitSection()) {
auto Attrs = GV->getAttributes();
if (Attrs.hasAttribute("bss-section") && Kind.isBSS())
return Attrs.getAttribute("bss-section").getValueAsString();
else if (Attrs.hasAttribute("rodata-section") && Kind.isReadOnly())
return Attrs.getAttribute("rodata-section").getValueAsString();
else if (Attrs.hasAttribute("relro-section") && Kind.isReadOnlyWithRel())
return Attrs.getAttribute("relro-section").getValueAsString();
else if (Attrs.hasAttribute("data-section") && Kind.isData())
return Attrs.getAttribute("data-section").getValueAsString();
}
return GO->getSection();
}
static MCSection *selectExplicitSectionGlobal(const GlobalObject *GO,
SectionKind Kind,
const TargetMachine &TM,
MCContext &Ctx, Mangler &Mang,
unsigned &NextUniqueID,
bool Retain, bool ForceUnique) {
StringRef SectionName = handlePragmaClangSection(GO, Kind);
// Infer section flags from the section name if we can.
Kind = getELFKindForNamedSection(SectionName, Kind);
unsigned Flags = getELFSectionFlags(Kind, TM.getTargetTriple());
auto [Group, IsComdat, ExtraFlags, Type, EntrySize] =
getGlobalObjectInfo(GO, TM, SectionName, Kind);
Flags |= ExtraFlags;
const unsigned UniqueID = calcUniqueIDUpdateFlagsAndSize(
GO, SectionName, Kind, TM, Ctx, Mang, Flags, EntrySize, NextUniqueID,
Retain, ForceUnique);
const MCSymbolELF *LinkedToSym = getLinkedToSymbol(GO, TM);
MCSectionELF *Section =
Ctx.getELFSection(SectionName, Type, Flags, EntrySize, Group, IsComdat,
UniqueID, LinkedToSym);
// Make sure that we did not get some other section with incompatible sh_link.
// This should not be possible due to UniqueID code above.
assert(Section->getLinkedToSymbol() == LinkedToSym &&
"Associated symbol mismatch between sections");
if (!(Ctx.getAsmInfo().useIntegratedAssembler() ||
Ctx.getAsmInfo().binutilsIsAtLeast(2, 35))) {
// If we are using GNU as before 2.35, then this symbol might have
// been placed in an incompatible mergeable section. Emit an error if this
// is the case to avoid creating broken output.
if ((Section->getFlags() & ELF::SHF_MERGE) &&
(Section->getEntrySize() != getEntrySizeForKind(Kind)))
GO->getContext().diagnose(LoweringDiagnosticInfo(
"Symbol '" + GO->getName() + "' from module '" +
(GO->getParent() ? GO->getParent()->getSourceFileName() : "unknown") +
"' required a section with entry-size=" +
Twine(getEntrySizeForKind(Kind)) + " but was placed in section '" +
SectionName + "' with entry-size=" + Twine(Section->getEntrySize()) +
": Explicit assignment by pragma or attribute of an incompatible "
"symbol to this section?"));
}
return Section;
}
MCSection *TargetLoweringObjectFileELF::getExplicitSectionGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
return selectExplicitSectionGlobal(GO, Kind, TM, getContext(), getMangler(),
NextUniqueID, Used.count(GO),
/* ForceUnique = */false);
}
static MCSectionELF *selectELFSectionForGlobal(
MCContext &Ctx, const GlobalObject *GO, SectionKind Kind, Mangler &Mang,
const TargetMachine &TM, bool EmitUniqueSection, unsigned Flags,
unsigned *NextUniqueID, const MCSymbolELF *AssociatedSymbol,
const MachineJumpTableEntry *MJTE = nullptr) {
bool UniqueSectionName = false;
unsigned UniqueID = MCSection::NonUniqueID;
if (EmitUniqueSection) {
if (TM.getUniqueSectionNames()) {
UniqueSectionName = true;
} else {
UniqueID = *NextUniqueID;
(*NextUniqueID)++;
}
}
SmallString<128> Name =
getELFSectionNameForGlobal(GO, Kind, Mang, TM, UniqueSectionName, MJTE);
auto [Group, IsComdat, ExtraFlags, Type, EntrySize] =
getGlobalObjectInfo(GO, TM, Name, Kind);
Flags |= ExtraFlags;
// Use 0 as the unique ID for execute-only text.
if (Kind.isExecuteOnly())
UniqueID = 0;
return Ctx.getELFSection(Name, Type, Flags, EntrySize, Group, IsComdat,
UniqueID, AssociatedSymbol);
}
static MCSection *selectELFSectionForGlobal(
MCContext &Ctx, const GlobalObject *GO, SectionKind Kind, Mangler &Mang,
const TargetMachine &TM, bool Retain, bool EmitUniqueSection,
unsigned Flags, unsigned *NextUniqueID) {
const MCSymbolELF *LinkedToSym = getLinkedToSymbol(GO, TM);
if (LinkedToSym) {
EmitUniqueSection = true;
Flags |= ELF::SHF_LINK_ORDER;
}
if (Retain) {
if (TM.getTargetTriple().isOSSolaris()) {
EmitUniqueSection = true;
Flags |= ELF::SHF_SUNW_NODISCARD;
} else if (Ctx.getAsmInfo().useIntegratedAssembler() ||
Ctx.getAsmInfo().binutilsIsAtLeast(2, 36)) {
EmitUniqueSection = true;
Flags |= ELF::SHF_GNU_RETAIN;
}
}
if (GO->hasMetadata(LLVMContext::MD_elf_section_properties))
EmitUniqueSection = true;
MCSectionELF *Section = selectELFSectionForGlobal(
Ctx, GO, Kind, Mang, TM, EmitUniqueSection, Flags,
NextUniqueID, LinkedToSym);
assert(Section->getLinkedToSymbol() == LinkedToSym);
return Section;
}
MCSection *TargetLoweringObjectFileELF::SelectSectionForGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
unsigned Flags = getELFSectionFlags(Kind, TM.getTargetTriple());
// If we have -ffunction-section or -fdata-section then we should emit the
// global value to a uniqued section specifically for it.
bool EmitUniqueSection = false;
if (!(Flags & ELF::SHF_MERGE) && !Kind.isCommon()) {
if (Kind.isText())
EmitUniqueSection = TM.getFunctionSections();
else
EmitUniqueSection = TM.getDataSections();
}
EmitUniqueSection |= GO->hasComdat();
return selectELFSectionForGlobal(getContext(), GO, Kind, getMangler(), TM,
Used.count(GO), EmitUniqueSection, Flags,
&NextUniqueID);
}
MCSection *TargetLoweringObjectFileELF::getUniqueSectionForFunction(
const Function &F, const TargetMachine &TM) const {
SectionKind Kind = SectionKind::getText();
unsigned Flags = getELFSectionFlags(Kind, TM.getTargetTriple());
// If the function's section names is pre-determined via pragma or a
// section attribute, call selectExplicitSectionGlobal.
if (F.hasSection())
return selectExplicitSectionGlobal(
&F, Kind, TM, getContext(), getMangler(), NextUniqueID,
Used.count(&F), /* ForceUnique = */true);
return selectELFSectionForGlobal(
getContext(), &F, Kind, getMangler(), TM, Used.count(&F),
/*EmitUniqueSection=*/true, Flags, &NextUniqueID);
}
MCSection *TargetLoweringObjectFileELF::getSectionForJumpTable(
const Function &F, const TargetMachine &TM) const {
return getSectionForJumpTable(F, TM, /*JTE=*/nullptr);
}
MCSection *TargetLoweringObjectFileELF::getSectionForJumpTable(
const Function &F, const TargetMachine &TM,
const MachineJumpTableEntry *JTE) const {
// If the function can be removed, produce a unique section so that
// the table doesn't prevent the removal.
const Comdat *C = F.getComdat();
bool EmitUniqueSection = TM.getFunctionSections() || C;
if (!EmitUniqueSection && !TM.getEnableStaticDataPartitioning())
return ReadOnlySection;
return selectELFSectionForGlobal(getContext(), &F, SectionKind::getReadOnly(),
getMangler(), TM, EmitUniqueSection,
ELF::SHF_ALLOC, &NextUniqueID,
/* AssociatedSymbol */ nullptr, JTE);
}
MCSection *TargetLoweringObjectFileELF::getSectionForLSDA(
const Function &F, const MCSymbol &FnSym, const TargetMachine &TM) const {
// If neither COMDAT nor function sections, use the monolithic LSDA section.
// Re-use this path if LSDASection is null as in the Arm EHABI.
if (!LSDASection || (!F.hasComdat() && !TM.getFunctionSections()))
return LSDASection;
const auto *LSDA = static_cast<const MCSectionELF *>(LSDASection);
unsigned Flags = LSDA->getFlags();
const MCSymbolELF *LinkedToSym = nullptr;
StringRef Group;
bool IsComdat = false;
if (const Comdat *C = getELFComdat(&F)) {
Flags |= ELF::SHF_GROUP;
Group = C->getName();
IsComdat = C->getSelectionKind() == Comdat::Any;
}
// Use SHF_LINK_ORDER to facilitate --gc-sections if we can use GNU ld>=2.36
// or LLD, which support mixed SHF_LINK_ORDER & non-SHF_LINK_ORDER.
if (TM.getFunctionSections() &&
(getContext().getAsmInfo().useIntegratedAssembler() &&
getContext().getAsmInfo().binutilsIsAtLeast(2, 36))) {
Flags |= ELF::SHF_LINK_ORDER;
LinkedToSym = static_cast<const MCSymbolELF *>(&FnSym);
}
// Append the function name as the suffix like GCC, assuming
// -funique-section-names applies to .gcc_except_table sections.
return getContext().getELFSection(
(TM.getUniqueSectionNames() ? LSDA->getName() + "." + F.getName()
: LSDA->getName()),
LSDA->getType(), Flags, 0, Group, IsComdat, MCSection::NonUniqueID,
LinkedToSym);
}
bool TargetLoweringObjectFileELF::shouldPutJumpTableInFunctionSection(
bool UsesLabelDifference, const Function &F) const {
// We can always create relative relocations, so use another section
// that can be marked non-executable.
return false;
}
/// Given a mergeable constant with the specified size and relocation
/// information, return a section that it should be placed in.
MCSection *TargetLoweringObjectFileELF::getSectionForConstant(
const DataLayout &DL, SectionKind Kind, const Constant *C, Align &Alignment,
const Function *F) const {
if (Kind.isMergeableConst4() && MergeableConst4Section)
return MergeableConst4Section;
if (Kind.isMergeableConst8() && MergeableConst8Section)
return MergeableConst8Section;
if (Kind.isMergeableConst16() && MergeableConst16Section)
return MergeableConst16Section;
if (Kind.isMergeableConst32() && MergeableConst32Section)
return MergeableConst32Section;
if (Kind.isReadOnly())
return ReadOnlySection;
assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
return DataRelROSection;
}
MCSection *TargetLoweringObjectFileELF::getSectionForConstant(
const DataLayout &DL, SectionKind Kind, const Constant *C, Align &Alignment,
const Function *F, StringRef SectionSuffix) const {
// TODO: Share code between this function and
// MCObjectInfo::initELFMCObjectFileInfo.
if (SectionSuffix.empty())
return getSectionForConstant(DL, Kind, C, Alignment, F);
auto &Context = getContext();
if (Kind.isMergeableConst4() && MergeableConst4Section)
return Context.getELFSection(".rodata.cst4." + SectionSuffix + ".",
ELF::SHT_PROGBITS,
ELF::SHF_ALLOC | ELF::SHF_MERGE, 4);
if (Kind.isMergeableConst8() && MergeableConst8Section)
return Context.getELFSection(".rodata.cst8." + SectionSuffix + ".",
ELF::SHT_PROGBITS,
ELF::SHF_ALLOC | ELF::SHF_MERGE, 8);
if (Kind.isMergeableConst16() && MergeableConst16Section)
return Context.getELFSection(".rodata.cst16." + SectionSuffix + ".",
ELF::SHT_PROGBITS,
ELF::SHF_ALLOC | ELF::SHF_MERGE, 16);
if (Kind.isMergeableConst32() && MergeableConst32Section)
return Context.getELFSection(".rodata.cst32." + SectionSuffix + ".",
ELF::SHT_PROGBITS,
ELF::SHF_ALLOC | ELF::SHF_MERGE, 32);
if (Kind.isReadOnly())
return Context.getELFSection(".rodata." + SectionSuffix + ".",
ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
return Context.getELFSection(".data.rel.ro." + SectionSuffix + ".",
ELF::SHT_PROGBITS,
ELF::SHF_ALLOC | ELF::SHF_WRITE);
}
/// Returns a unique section for the given machine basic block.
MCSection *TargetLoweringObjectFileELF::getSectionForMachineBasicBlock(
const Function &F, const MachineBasicBlock &MBB,
const TargetMachine &TM) const {
assert(MBB.isBeginSection() && "Basic block does not start a section!");
unsigned UniqueID = MCSection::NonUniqueID;
// For cold sections use the .text.split. prefix along with the parent
// function name. All cold blocks for the same function go to the same
// section. Similarly all exception blocks are grouped by symbol name
// under the .text.eh prefix. For regular sections, we either use a unique
// name, or a unique ID for the section.
SmallString<128> Name;
StringRef FunctionSectionName = MBB.getParent()->getSection()->getName();
if (FunctionSectionName == ".text" ||
FunctionSectionName.starts_with(".text.")) {
// Function is in a regular .text section.
StringRef FunctionName = MBB.getParent()->getName();
if (MBB.getSectionID() == MBBSectionID::ColdSectionID) {
Name += BBSectionsColdTextPrefix;
Name += FunctionName;
} else if (MBB.getSectionID() == MBBSectionID::ExceptionSectionID) {
Name += ".text.eh.";
Name += FunctionName;
} else {
Name += FunctionSectionName;
if (TM.getUniqueBasicBlockSectionNames()) {
if (!Name.ends_with("."))
Name += ".";
Name += MBB.getSymbol()->getName();
} else {
UniqueID = NextUniqueID++;
}
}
} else {
// If the original function has a custom non-dot-text section, then emit
// all basic block sections into that section too, each with a unique id.
Name = FunctionSectionName;
UniqueID = NextUniqueID++;
}
unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_EXECINSTR;
std::string GroupName;
if (F.hasComdat()) {
Flags |= ELF::SHF_GROUP;
GroupName = F.getComdat()->getName().str();
}
return getContext().getELFSection(Name, ELF::SHT_PROGBITS, Flags,
0 /* Entry Size */, GroupName,
F.hasComdat(), UniqueID, nullptr);
}
static MCSectionELF *getStaticStructorSection(MCContext &Ctx, bool UseInitArray,
bool IsCtor, unsigned Priority,
const MCSymbol *KeySym) {
std::string Name;
unsigned Type;
unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE;
StringRef Comdat = KeySym ? KeySym->getName() : "";
if (KeySym)
Flags |= ELF::SHF_GROUP;
if (UseInitArray) {
if (IsCtor) {
Type = ELF::SHT_INIT_ARRAY;
Name = ".init_array";
} else {
Type = ELF::SHT_FINI_ARRAY;
Name = ".fini_array";
}
if (Priority != 65535) {
Name += '.';
Name += utostr(Priority);
}
} else {
// The default scheme is .ctor / .dtor, so we have to invert the priority
// numbering.
if (IsCtor)
Name = ".ctors";
else
Name = ".dtors";
if (Priority != 65535)
raw_string_ostream(Name) << format(".%05u", 65535 - Priority);
Type = ELF::SHT_PROGBITS;
}
return Ctx.getELFSection(Name, Type, Flags, 0, Comdat, /*IsComdat=*/true);
}
MCSection *TargetLoweringObjectFileELF::getStaticCtorSection(
unsigned Priority, const MCSymbol *KeySym) const {
return getStaticStructorSection(getContext(), UseInitArray, true, Priority,
KeySym);
}
MCSection *TargetLoweringObjectFileELF::getStaticDtorSection(
unsigned Priority, const MCSymbol *KeySym) const {
return getStaticStructorSection(getContext(), UseInitArray, false, Priority,
KeySym);
}
const MCExpr *TargetLoweringObjectFileELF::lowerSymbolDifference(
const MCSymbol *LHS, const MCSymbol *RHS, int64_t Addend,
std::optional<int64_t> PCRelativeOffset) const {
auto &Ctx = getContext();
const MCExpr *Res;
// Return a relocatable expression with the PLT specifier, %plt(GV) or
// %plt(GV-RHS).
if (PCRelativeOffset && PLTPCRelativeSpecifier) {
Res = MCSymbolRefExpr::create(LHS, Ctx);
// The current location is RHS plus *PCRelativeOffset. Compensate for it.
Addend += *PCRelativeOffset;
if (Addend)
Res = MCBinaryExpr::createAdd(Res, MCConstantExpr::create(Addend, Ctx),
Ctx);
return MCSpecifierExpr::create(Res, PLTPCRelativeSpecifier, getContext());
}
if (!PLTRelativeSpecifier)
return nullptr;
Res = MCBinaryExpr::createSub(
MCSymbolRefExpr::create(LHS, PLTRelativeSpecifier, Ctx),
MCSymbolRefExpr::create(RHS, Ctx), Ctx);
if (Addend)
Res =
MCBinaryExpr::createAdd(Res, MCConstantExpr::create(Addend, Ctx), Ctx);
return Res;
}
// Reference the PLT entry of a function, optionally with a subtrahend (`RHS`).
const MCExpr *TargetLoweringObjectFileELF::lowerDSOLocalEquivalent(
const MCSymbol *LHS, const MCSymbol *RHS, int64_t Addend,
std::optional<int64_t> PCRelativeOffset, const TargetMachine &TM) const {
if (RHS)
return lowerSymbolDifference(LHS, RHS, Addend, PCRelativeOffset);
// Only the legacy MCSymbolRefExpr::VariantKind approach is implemented.
// Reference LHS@plt or LHS@plt - RHS.
if (PLTRelativeSpecifier)
return MCSymbolRefExpr::create(LHS, PLTRelativeSpecifier, getContext());
return nullptr;
}
MCSection *TargetLoweringObjectFileELF::getSectionForCommandLines() const {
// Use ".GCC.command.line" since this feature is to support clang's
// -frecord-gcc-switches which in turn attempts to mimic GCC's switch of the
// same name.
return getContext().getELFSection(".GCC.command.line", ELF::SHT_PROGBITS,
ELF::SHF_MERGE | ELF::SHF_STRINGS, 1);
}
void
TargetLoweringObjectFileELF::InitializeELF(bool UseInitArray_) {
UseInitArray = UseInitArray_;
MCContext &Ctx = getContext();
if (!UseInitArray) {
StaticCtorSection = Ctx.getELFSection(".ctors", ELF::SHT_PROGBITS,
ELF::SHF_ALLOC | ELF::SHF_WRITE);
StaticDtorSection = Ctx.getELFSection(".dtors", ELF::SHT_PROGBITS,
ELF::SHF_ALLOC | ELF::SHF_WRITE);
return;
}
StaticCtorSection = Ctx.getELFSection(".init_array", ELF::SHT_INIT_ARRAY,
ELF::SHF_WRITE | ELF::SHF_ALLOC);
StaticDtorSection = Ctx.getELFSection(".fini_array", ELF::SHT_FINI_ARRAY,
ELF::SHF_WRITE | ELF::SHF_ALLOC);
}
//===----------------------------------------------------------------------===//
// MachO
//===----------------------------------------------------------------------===//
TargetLoweringObjectFileMachO::TargetLoweringObjectFileMachO() {
SupportIndirectSymViaGOTPCRel = true;
}
void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
const TargetMachine &TM) {
TargetLoweringObjectFile::Initialize(Ctx, TM);
if (TM.getRelocationModel() == Reloc::Static) {
StaticCtorSection = Ctx.getMachOSection("__TEXT", "__constructor", 0,
SectionKind::getData());
StaticDtorSection = Ctx.getMachOSection("__TEXT", "__destructor", 0,
SectionKind::getData());
} else {
StaticCtorSection = Ctx.getMachOSection("__DATA", "__mod_init_func",
MachO::S_MOD_INIT_FUNC_POINTERS,
SectionKind::getData());
StaticDtorSection = Ctx.getMachOSection("__DATA", "__mod_term_func",
MachO::S_MOD_TERM_FUNC_POINTERS,
SectionKind::getData());
}
PersonalityEncoding =
dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
LSDAEncoding = dwarf::DW_EH_PE_pcrel;
TTypeEncoding =
dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
}
MCSection *TargetLoweringObjectFileMachO::getStaticDtorSection(
unsigned Priority, const MCSymbol *KeySym) const {
return StaticDtorSection;
// In userspace, we lower global destructors via atexit(), but kernel/kext
// environments do not provide this function so we still need to support the
// legacy way here.
// See the -disable-atexit-based-global-dtor-lowering CodeGen flag for more
// context.
}
void TargetLoweringObjectFileMachO::emitModuleMetadata(MCStreamer &Streamer,
Module &M) const {
// Emit the linker options if present.
emitLinkerDirectives(Streamer, M);
emitPseudoProbeDescMetadata(Streamer, M);
unsigned VersionVal = 0;
unsigned ImageInfoFlags = 0;
StringRef SectionVal;
GetObjCImageInfo(M, VersionVal, ImageInfoFlags, SectionVal);
emitCGProfileMetadata(Streamer, M);
// The section is mandatory. If we don't have it, then we don't have GC info.
if (SectionVal.empty())
return;
StringRef Segment, Section;
unsigned TAA = 0, StubSize = 0;
bool TAAParsed;
if (Error E = MCSectionMachO::ParseSectionSpecifier(
SectionVal, Segment, Section, TAA, TAAParsed, StubSize)) {
// If invalid, report the error with report_fatal_error.
report_fatal_error("Invalid section specifier '" + Section +
"': " + toString(std::move(E)) + ".");
}
// Get the section.
MCSectionMachO *S = getContext().getMachOSection(
Segment, Section, TAA, StubSize, SectionKind::getData());
Streamer.switchSection(S);
Streamer.emitLabel(getContext().
getOrCreateSymbol(StringRef("L_OBJC_IMAGE_INFO")));
Streamer.emitInt32(VersionVal);
Streamer.emitInt32(ImageInfoFlags);
Streamer.addBlankLine();
}
void TargetLoweringObjectFileMachO::emitLinkerDirectives(MCStreamer &Streamer,
Module &M) const {
if (auto *LinkerOptions = M.getNamedMetadata("llvm.linker.options")) {
for (const auto *Option : LinkerOptions->operands()) {
SmallVector<std::string, 4> StrOptions;
for (const auto &Piece : cast<MDNode>(Option)->operands())
StrOptions.push_back(std::string(cast<MDString>(Piece)->getString()));
Streamer.emitLinkerOptions(StrOptions);
}
}
}
static void checkMachOComdat(const GlobalValue *GV) {
const Comdat *C = GV->getComdat();
if (!C)
return;
report_fatal_error("MachO doesn't support COMDATs, '" + C->getName() +
"' cannot be lowered.");
}
MCSection *TargetLoweringObjectFileMachO::getExplicitSectionGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
StringRef SectionName = handlePragmaClangSection(GO, Kind);
// Parse the section specifier and create it if valid.
StringRef Segment, Section;
unsigned TAA = 0, StubSize = 0;
bool TAAParsed;
checkMachOComdat(GO);
if (Error E = MCSectionMachO::ParseSectionSpecifier(
SectionName, Segment, Section, TAA, TAAParsed, StubSize)) {
// If invalid, report the error with report_fatal_error.
report_fatal_error("Global variable '" + GO->getName() +
"' has an invalid section specifier '" +
GO->getSection() + "': " + toString(std::move(E)) + ".");
}
// Get the section.
MCSectionMachO *S =
getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
// If TAA wasn't set by ParseSectionSpecifier() above,
// use the value returned by getMachOSection() as a default.
if (!TAAParsed)
TAA = S->getTypeAndAttributes();
// Okay, now that we got the section, verify that the TAA & StubSize agree.
// If the user declared multiple globals with different section flags, we need
// to reject it here.
if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
// If invalid, report the error with report_fatal_error.
report_fatal_error("Global variable '" + GO->getName() +
"' section type or attributes does not match previous"
" section specifier");
}
return S;
}
MCSection *TargetLoweringObjectFileMachO::SelectSectionForGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
checkMachOComdat(GO);
// Handle thread local data.
if (Kind.isThreadBSS()) return TLSBSSSection;
if (Kind.isThreadData()) return TLSDataSection;
if (Kind.isText())
return GO->isWeakForLinker() ? TextCoalSection : TextSection;
// If this is weak/linkonce, put this in a coalescable section, either in text
// or data depending on if it is writable.
if (GO->isWeakForLinker()) {
if (Kind.isReadOnly())
return ConstTextCoalSection;
if (Kind.isReadOnlyWithRel())
return ConstDataCoalSection;
return DataCoalSection;
}
// FIXME: Alignment check should be handled by section classifier.
if (Kind.isMergeable1ByteCString() &&
GO->getDataLayout().getPreferredAlign(
cast<GlobalVariable>(GO)) < Align(32))
return CStringSection;
// Do not put 16-bit arrays in the UString section if they have an
// externally visible label, this runs into issues with certain linker
// versions.
if (Kind.isMergeable2ByteCString() && !GO->hasExternalLinkage() &&
GO->getDataLayout().getPreferredAlign(
cast<GlobalVariable>(GO)) < Align(32))
return UStringSection;
// With MachO only variables whose corresponding symbol starts with 'l' or
// 'L' can be merged, so we only try merging GVs with private linkage.
if (GO->hasPrivateLinkage() && Kind.isMergeableConst()) {
if (Kind.isMergeableConst4())
return FourByteConstantSection;
if (Kind.isMergeableConst8())
return EightByteConstantSection;
if (Kind.isMergeableConst16())
return SixteenByteConstantSection;
}
// Otherwise, if it is readonly, but not something we can specially optimize,
// just drop it in .const.
if (Kind.isReadOnly())
return ReadOnlySection;
// If this is marked const, put it into a const section. But if the dynamic
// linker needs to write to it, put it in the data segment.
if (Kind.isReadOnlyWithRel())
return ConstDataSection;
// Put zero initialized globals with strong external linkage in the
// DATA, __common section with the .zerofill directive.
if (Kind.isBSSExtern())
return DataCommonSection;
// Put zero initialized globals with local linkage in __DATA,__bss directive
// with the .zerofill directive (aka .lcomm).
if (Kind.isBSSLocal())
return DataBSSSection;
// Otherwise, just drop the variable in the normal data section.
return DataSection;
}
MCSection *TargetLoweringObjectFileMachO::getSectionForConstant(
const DataLayout &DL, SectionKind Kind, const Constant *C, Align &Alignment,
const Function *F) const {
// If this constant requires a relocation, we have to put it in the data
// segment, not in the text segment.
if (Kind.isData() || Kind.isReadOnlyWithRel())
return ConstDataSection;
if (Kind.isMergeableConst4())
return FourByteConstantSection;
if (Kind.isMergeableConst8())
return EightByteConstantSection;
if (Kind.isMergeableConst16())
return SixteenByteConstantSection;
return ReadOnlySection; // .const
}
MCSection *TargetLoweringObjectFileMachO::getSectionForCommandLines() const {
return getContext().getMachOSection("__TEXT", "__command_line", 0,
SectionKind::getReadOnly());
}
const MCExpr *TargetLoweringObjectFileMachO::getTTypeGlobalReference(
const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM,
MachineModuleInfo *MMI, MCStreamer &Streamer) const {
// The mach-o version of this method defaults to returning a stub reference.
if (Encoding & DW_EH_PE_indirect) {
MachineModuleInfoMachO &MachOMMI =
MMI->getObjFileInfo<MachineModuleInfoMachO>();
MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", TM);
// Add information about the stub reference to MachOMMI so that the stub
// gets emitted by the asmprinter.
MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
if (!StubSym.getPointer()) {
MCSymbol *Sym = TM.getSymbol(GV);
StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
}
return TargetLoweringObjectFile::
getTTypeReference(MCSymbolRefExpr::create(SSym, getContext()),
Encoding & ~DW_EH_PE_indirect, Streamer);
}
return TargetLoweringObjectFile::getTTypeGlobalReference(GV, Encoding, TM,
MMI, Streamer);
}
MCSymbol *TargetLoweringObjectFileMachO::getCFIPersonalitySymbol(
const GlobalValue *GV, const TargetMachine &TM,
MachineModuleInfo *MMI) const {
// The mach-o version of this method defaults to returning a stub reference.
MachineModuleInfoMachO &MachOMMI =
MMI->getObjFileInfo<MachineModuleInfoMachO>();
MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", TM);
// Add information about the stub reference to MachOMMI so that the stub
// gets emitted by the asmprinter.
MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
if (!StubSym.getPointer()) {
MCSymbol *Sym = TM.getSymbol(GV);
StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
}
return SSym;
}
const MCExpr *TargetLoweringObjectFileMachO::getIndirectSymViaGOTPCRel(
const GlobalValue *GV, const MCSymbol *Sym, const MCValue &MV,
int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const {
// Although MachO 32-bit targets do not explicitly have a GOTPCREL relocation
// as 64-bit do, we replace the GOT equivalent by accessing the final symbol
// through a non_lazy_ptr stub instead. One advantage is that it allows the
// computation of deltas to final external symbols. Example:
//
// _extgotequiv:
// .long _extfoo
//
// _delta:
// .long _extgotequiv-_delta
//
// is transformed to:
//
// _delta:
// .long L_extfoo$non_lazy_ptr-(_delta+0)
//
// .section __IMPORT,__pointers,non_lazy_symbol_pointers
// L_extfoo$non_lazy_ptr:
// .indirect_symbol _extfoo
// .long 0
//
// The indirect symbol table (and sections of non_lazy_symbol_pointers type)
// may point to both local (same translation unit) and global (other
// translation units) symbols. Example:
//
// .section __DATA,__pointers,non_lazy_symbol_pointers
// L1:
// .indirect_symbol _myGlobal
// .long 0
// L2:
// .indirect_symbol _myLocal
// .long _myLocal
//
// If the symbol is local, instead of the symbol's index, the assembler
// places the constant INDIRECT_SYMBOL_LOCAL into the indirect symbol table.
// Then the linker will notice the constant in the table and will look at the
// content of the symbol.
MachineModuleInfoMachO &MachOMMI =
MMI->getObjFileInfo<MachineModuleInfoMachO>();
MCContext &Ctx = getContext();
// The offset must consider the original displacement from the base symbol
// since 32-bit targets don't have a GOTPCREL to fold the PC displacement.
Offset = -MV.getConstant();
const MCSymbol *BaseSym = MV.getSubSym();
// Access the final symbol via sym$non_lazy_ptr and generate the appropriated
// non_lazy_ptr stubs.
SmallString<128> Name;
StringRef Suffix = "$non_lazy_ptr";
Name += MMI->getModule()->getDataLayout().getInternalSymbolPrefix();
Name += Sym->getName();
Name += Suffix;
MCSymbol *Stub = Ctx.getOrCreateSymbol(Name);
MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(Stub);
if (!StubSym.getPointer())
StubSym = MachineModuleInfoImpl::StubValueTy(const_cast<MCSymbol *>(Sym),
!GV->hasLocalLinkage());
const MCExpr *BSymExpr = MCSymbolRefExpr::create(BaseSym, Ctx);
const MCExpr *LHS = MCSymbolRefExpr::create(Stub, Ctx);
if (!Offset)
return MCBinaryExpr::createSub(LHS, BSymExpr, Ctx);
const MCExpr *RHS =
MCBinaryExpr::createAdd(BSymExpr, MCConstantExpr::create(Offset, Ctx), Ctx);
return MCBinaryExpr::createSub(LHS, RHS, Ctx);
}
static bool canUsePrivateLabel(const MCAsmInfo &AsmInfo,
const MCSection &Section) {
if (!MCAsmInfoDarwin::isSectionAtomizableBySymbols(Section))
return true;
// FIXME: we should be able to use private labels for sections that can't be
// dead-stripped (there's no issue with blocking atomization there), but `ld
// -r` sometimes drops the no_dead_strip attribute from sections so for safety
// we don't allow it.
return false;
}
void TargetLoweringObjectFileMachO::getNameWithPrefix(
SmallVectorImpl<char> &OutName, const GlobalValue *GV,
const TargetMachine &TM) const {
bool CannotUsePrivateLabel = true;
if (auto *GO = GV->getAliaseeObject()) {
SectionKind GOKind = TargetLoweringObjectFile::getKindForGlobal(GO, TM);
const MCSection *TheSection = SectionForGlobal(GO, GOKind, TM);
CannotUsePrivateLabel = !canUsePrivateLabel(TM.getMCAsmInfo(), *TheSection);
}
getMangler().getNameWithPrefix(OutName, GV, CannotUsePrivateLabel);
}
//===----------------------------------------------------------------------===//
// COFF
//===----------------------------------------------------------------------===//
static unsigned
getCOFFSectionFlags(SectionKind K, const TargetMachine &TM) {
unsigned Flags = 0;
bool isThumb = TM.getTargetTriple().getArch() == Triple::thumb;
if (K.isMetadata())
Flags |=
COFF::IMAGE_SCN_MEM_DISCARDABLE;
else if (K.isExclude())
Flags |=
COFF::IMAGE_SCN_LNK_REMOVE | COFF::IMAGE_SCN_MEM_DISCARDABLE;
else if (K.isText())
Flags |=
COFF::IMAGE_SCN_MEM_EXECUTE |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_CNT_CODE |
(isThumb ? COFF::IMAGE_SCN_MEM_16BIT : (COFF::SectionCharacteristics)0);
else if (K.isBSS())
Flags |=
COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE;
else if (K.isThreadLocal())
Flags |=
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE;
else if (K.isReadOnly() || K.isReadOnlyWithRel())
Flags |=
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ;
else if (K.isWriteable())
Flags |=
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE;
return Flags;
}
static const GlobalValue *getComdatGVForCOFF(const GlobalValue *GV) {
const Comdat *C = GV->getComdat();
assert(C && "expected GV to have a Comdat!");
StringRef ComdatGVName = C->getName();
const GlobalValue *ComdatGV = GV->getParent()->getNamedValue(ComdatGVName);
if (!ComdatGV)
report_fatal_error("Associative COMDAT symbol '" + ComdatGVName +
"' does not exist.");
if (ComdatGV->getComdat() != C)
report_fatal_error("Associative COMDAT symbol '" + ComdatGVName +
"' is not a key for its COMDAT.");
return ComdatGV;
}
static int getSelectionForCOFF(const GlobalValue *GV) {
if (const Comdat *C = GV->getComdat()) {
const GlobalValue *ComdatKey = getComdatGVForCOFF(GV);
if (const auto *GA = dyn_cast<GlobalAlias>(ComdatKey))
ComdatKey = GA->getAliaseeObject();
if (ComdatKey == GV) {
switch (C->getSelectionKind()) {
case Comdat::Any:
return COFF::IMAGE_COMDAT_SELECT_ANY;
case Comdat::ExactMatch:
return COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH;
case Comdat::Largest:
return COFF::IMAGE_COMDAT_SELECT_LARGEST;
case Comdat::NoDeduplicate:
return COFF::IMAGE_COMDAT_SELECT_NODUPLICATES;
case Comdat::SameSize:
return COFF::IMAGE_COMDAT_SELECT_SAME_SIZE;
}
} else {
return COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE;
}
}
return 0;
}
MCSection *TargetLoweringObjectFileCOFF::getExplicitSectionGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
StringRef Name = handlePragmaClangSection(GO, Kind);
if (Name == getInstrProfSectionName(IPSK_covmap, Triple::COFF,
/*AddSegmentInfo=*/false) ||
Name == getInstrProfSectionName(IPSK_covfun, Triple::COFF,
/*AddSegmentInfo=*/false) ||
Name == getInstrProfSectionName(IPSK_covdata, Triple::COFF,
/*AddSegmentInfo=*/false) ||
Name == getInstrProfSectionName(IPSK_covname, Triple::COFF,
/*AddSegmentInfo=*/false) ||
Name == ".llvmbc" || Name == ".llvmcmd")
Kind = SectionKind::getMetadata();
int Selection = 0;
unsigned Characteristics = getCOFFSectionFlags(Kind, TM);
StringRef COMDATSymName = "";
if (GO->hasComdat()) {
Selection = getSelectionForCOFF(GO);
const GlobalValue *ComdatGV;
if (Selection == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
ComdatGV = getComdatGVForCOFF(GO);
else
ComdatGV = GO;
if (!ComdatGV->hasPrivateLinkage()) {
MCSymbol *Sym = TM.getSymbol(ComdatGV);
COMDATSymName = Sym->getName();
Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
} else {
Selection = 0;
}
}
return getContext().getCOFFSection(Name, Characteristics, COMDATSymName,
Selection);
}
static StringRef getCOFFSectionNameForUniqueGlobal(SectionKind Kind) {
if (Kind.isText())
return ".text";
if (Kind.isBSS())
return ".bss";
if (Kind.isThreadLocal())
return ".tls$";
if (Kind.isReadOnly() || Kind.isReadOnlyWithRel())
return ".rdata";
return ".data";
}
MCSection *TargetLoweringObjectFileCOFF::SelectSectionForGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
// If we have -ffunction-sections then we should emit the global value to a
// uniqued section specifically for it.
bool EmitUniquedSection;
if (Kind.isText())
EmitUniquedSection = TM.getFunctionSections();
else
EmitUniquedSection = TM.getDataSections();
if ((EmitUniquedSection && !Kind.isCommon()) || GO->hasComdat()) {
SmallString<256> Name = getCOFFSectionNameForUniqueGlobal(Kind);
unsigned Characteristics = getCOFFSectionFlags(Kind, TM);
Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
int Selection = getSelectionForCOFF(GO);
if (!Selection)
Selection = COFF::IMAGE_COMDAT_SELECT_NODUPLICATES;
const GlobalValue *ComdatGV;
if (GO->hasComdat())
ComdatGV = getComdatGVForCOFF(GO);
else
ComdatGV = GO;
unsigned UniqueID = MCSection::NonUniqueID;
if (EmitUniquedSection)
UniqueID = NextUniqueID++;
if (!ComdatGV->hasPrivateLinkage()) {
MCSymbol *Sym = TM.getSymbol(ComdatGV);
StringRef COMDATSymName = Sym->getName();
if (const auto *F = dyn_cast<Function>(GO))
if (std::optional<StringRef> Prefix = F->getSectionPrefix())
raw_svector_ostream(Name) << '$' << *Prefix;
// Append "$symbol" to the section name *before* IR-level mangling is
// applied when targetting mingw. This is what GCC does, and the ld.bfd
// COFF linker will not properly handle comdats otherwise.
if (getContext().getTargetTriple().isOSCygMing())
raw_svector_ostream(Name) << '$' << ComdatGV->getName();
return getContext().getCOFFSection(Name, Characteristics, COMDATSymName,
Selection, UniqueID);
} else {
SmallString<256> TmpData;
getMangler().getNameWithPrefix(TmpData, GO, /*CannotUsePrivateLabel=*/true);
return getContext().getCOFFSection(Name, Characteristics, TmpData,
Selection, UniqueID);
}
}
if (Kind.isText())
return TextSection;
if (Kind.isThreadLocal())
return TLSDataSection;
if (Kind.isReadOnly() || Kind.isReadOnlyWithRel())
return ReadOnlySection;
// Note: we claim that common symbols are put in BSSSection, but they are
// really emitted with the magic .comm directive, which creates a symbol table
// entry but not a section.
if (Kind.isBSS() || Kind.isCommon())
return BSSSection;
return DataSection;
}
void TargetLoweringObjectFileCOFF::getNameWithPrefix(
SmallVectorImpl<char> &OutName, const GlobalValue *GV,
const TargetMachine &TM) const {
bool CannotUsePrivateLabel = false;
if (GV->hasPrivateLinkage() &&
((isa<Function>(GV) && TM.getFunctionSections()) ||
(isa<GlobalVariable>(GV) && TM.getDataSections())))
CannotUsePrivateLabel = true;
getMangler().getNameWithPrefix(OutName, GV, CannotUsePrivateLabel);
}
MCSection *TargetLoweringObjectFileCOFF::getSectionForJumpTable(
const Function &F, const TargetMachine &TM) const {
// If the function can be removed, produce a unique section so that
// the table doesn't prevent the removal.
const Comdat *C = F.getComdat();
bool EmitUniqueSection = TM.getFunctionSections() || C;
if (!EmitUniqueSection)
return ReadOnlySection;
// FIXME: we should produce a symbol for F instead.
if (F.hasPrivateLinkage())
return ReadOnlySection;
MCSymbol *Sym = TM.getSymbol(&F);
StringRef COMDATSymName = Sym->getName();
SectionKind Kind = SectionKind::getReadOnly();
StringRef SecName = getCOFFSectionNameForUniqueGlobal(Kind);
unsigned Characteristics = getCOFFSectionFlags(Kind, TM);
Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
unsigned UniqueID = NextUniqueID++;
return getContext().getCOFFSection(SecName, Characteristics, COMDATSymName,
COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE,
UniqueID);
}
bool TargetLoweringObjectFileCOFF::shouldPutJumpTableInFunctionSection(
bool UsesLabelDifference, const Function &F) const {
if (TM->getTargetTriple().getArch() == Triple::x86_64) {
if (!JumpTableInFunctionSection) {
// We can always create relative relocations, so use another section
// that can be marked non-executable.
return false;
}
}
return TargetLoweringObjectFile::shouldPutJumpTableInFunctionSection(
UsesLabelDifference, F);
}
void TargetLoweringObjectFileCOFF::emitModuleMetadata(MCStreamer &Streamer,
Module &M) const {
emitLinkerDirectives(Streamer, M);
unsigned Version = 0;
unsigned Flags = 0;
StringRef Section;
GetObjCImageInfo(M, Version, Flags, Section);
if (!Section.empty()) {
auto &C = getContext();
auto *S = C.getCOFFSection(Section, COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ);
Streamer.switchSection(S);
Streamer.emitLabel(C.getOrCreateSymbol(StringRef("OBJC_IMAGE_INFO")));
Streamer.emitInt32(Version);
Streamer.emitInt32(Flags);
Streamer.addBlankLine();
}
emitCGProfileMetadata(Streamer, M);
emitPseudoProbeDescMetadata(Streamer, M, [](MCStreamer &Streamer) {
if (MCSymbol *Sym =
static_cast<MCSectionCOFF *>(Streamer.getCurrentSectionOnly())
->getCOMDATSymbol())
if (Sym->isUndefined()) {
// COMDAT symbol must be external to perform deduplication.
Streamer.emitSymbolAttribute(Sym, MCSA_Global);
Streamer.emitLabel(Sym);
}
});
}
void TargetLoweringObjectFileCOFF::emitLinkerDirectives(
MCStreamer &Streamer, Module &M) const {
if (NamedMDNode *LinkerOptions = M.getNamedMetadata("llvm.linker.options")) {
// Emit the linker options to the linker .drectve section. According to the
// spec, this section is a space-separated string containing flags for
// linker.
MCSection *Sec = getDrectveSection();
Streamer.switchSection(Sec);
for (const auto *Option : LinkerOptions->operands()) {
for (const auto &Piece : cast<MDNode>(Option)->operands()) {
// Lead with a space for consistency with our dllexport implementation.
std::string Directive(" ");
Directive.append(std::string(cast<MDString>(Piece)->getString()));
Streamer.emitBytes(Directive);
}
}
}
// Emit /EXPORT: flags for each exported global as necessary.
std::string Flags;
for (const GlobalValue &GV : M.global_values()) {
raw_string_ostream OS(Flags);
emitLinkerFlagsForGlobalCOFF(OS, &GV, getContext().getTargetTriple(),
getMangler());
if (!Flags.empty()) {
Streamer.switchSection(getDrectveSection());
Streamer.emitBytes(Flags);
}
Flags.clear();
}
// Emit /INCLUDE: flags for each used global as necessary.
if (const auto *LU = M.getNamedGlobal("llvm.used")) {
assert(LU->hasInitializer() && "expected llvm.used to have an initializer");
assert(isa<ArrayType>(LU->getValueType()) &&
"expected llvm.used to be an array type");
if (const auto *A = cast<ConstantArray>(LU->getInitializer())) {
for (const Value *Op : A->operands()) {
const auto *GV = cast<GlobalValue>(Op->stripPointerCasts());
// Global symbols with internal or private linkage are not visible to
// the linker, and thus would cause an error when the linker tried to
// preserve the symbol due to the `/include:` directive.
if (GV->hasLocalLinkage())
continue;
raw_string_ostream OS(Flags);
emitLinkerFlagsForUsedCOFF(OS, GV, getContext().getTargetTriple(),
getMangler());
if (!Flags.empty()) {
Streamer.switchSection(getDrectveSection());
Streamer.emitBytes(Flags);
}
Flags.clear();
}
}
}
}
void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
const TargetMachine &TM) {
TargetLoweringObjectFile::Initialize(Ctx, TM);
this->TM = &TM;
const Triple &T = TM.getTargetTriple();
if (T.isWindowsMSVCEnvironment() || T.isWindowsItaniumEnvironment()) {
StaticCtorSection =
Ctx.getCOFFSection(".CRT$XCU", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ);
StaticDtorSection =
Ctx.getCOFFSection(".CRT$XTX", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ);
} else {
StaticCtorSection = Ctx.getCOFFSection(
".ctors", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE);
StaticDtorSection = Ctx.getCOFFSection(
".dtors", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE);
}
}
static MCSectionCOFF *getCOFFStaticStructorSection(MCContext &Ctx,
const Triple &T, bool IsCtor,
unsigned Priority,
const MCSymbol *KeySym,
MCSectionCOFF *Default) {
if (T.isWindowsMSVCEnvironment() || T.isWindowsItaniumEnvironment()) {
// If the priority is the default, use .CRT$XCU, possibly associative.
if (Priority == 65535)
return Ctx.getAssociativeCOFFSection(Default, KeySym, 0);
// Otherwise, we need to compute a new section name. Low priorities should
// run earlier. The linker will sort sections ASCII-betically, and we need a
// string that sorts between .CRT$XCA and .CRT$XCU. In the general case, we
// make a name like ".CRT$XCT12345", since that runs before .CRT$XCU. Really
// low priorities need to sort before 'L', since the CRT uses that
// internally, so we use ".CRT$XCA00001" for them. We have a contract with
// the frontend that "init_seg(compiler)" corresponds to priority 200 and
// "init_seg(lib)" corresponds to priority 400, and those respectively use
// 'C' and 'L' without the priority suffix. Priorities between 200 and 400
// use 'C' with the priority as a suffix.
SmallString<24> Name;
char LastLetter = 'T';
bool AddPrioritySuffix = Priority != 200 && Priority != 400;
if (Priority < 200)
LastLetter = 'A';
else if (Priority < 400)
LastLetter = 'C';
else if (Priority == 400)
LastLetter = 'L';
raw_svector_ostream OS(Name);
OS << ".CRT$X" << (IsCtor ? "C" : "T") << LastLetter;
if (AddPrioritySuffix)
OS << format("%05u", Priority);
MCSectionCOFF *Sec = Ctx.getCOFFSection(
Name, COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ);
return Ctx.getAssociativeCOFFSection(Sec, KeySym, 0);
}
std::string Name = IsCtor ? ".ctors" : ".dtors";
if (Priority != 65535)
raw_string_ostream(Name) << format(".%05u", 65535 - Priority);
return Ctx.getAssociativeCOFFSection(
Ctx.getCOFFSection(Name, COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE),
KeySym, 0);
}
MCSection *TargetLoweringObjectFileCOFF::getStaticCtorSection(
unsigned Priority, const MCSymbol *KeySym) const {
return getCOFFStaticStructorSection(
getContext(), getContext().getTargetTriple(), true, Priority, KeySym,
static_cast<MCSectionCOFF *>(StaticCtorSection));
}
MCSection *TargetLoweringObjectFileCOFF::getStaticDtorSection(
unsigned Priority, const MCSymbol *KeySym) const {
return getCOFFStaticStructorSection(
getContext(), getContext().getTargetTriple(), false, Priority, KeySym,
static_cast<MCSectionCOFF *>(StaticDtorSection));
}
const MCExpr *TargetLoweringObjectFileCOFF::lowerRelativeReference(
const GlobalValue *LHS, const GlobalValue *RHS, int64_t Addend,
std::optional<int64_t> PCRelativeOffset, const TargetMachine &TM) const {
const Triple &T = TM.getTargetTriple();
if (T.isOSCygMing())
return nullptr;
// Our symbols should exist in address space zero, cowardly no-op if
// otherwise.
if (LHS->getType()->getPointerAddressSpace() != 0 ||
RHS->getType()->getPointerAddressSpace() != 0)
return nullptr;
// Both ptrtoint instructions must wrap global objects:
// - Only global variables are eligible for image relative relocations.
// - The subtrahend refers to the special symbol __ImageBase, a GlobalVariable.
// We expect __ImageBase to be a global variable without a section, externally
// defined.
//
// It should look something like this: @__ImageBase = external constant i8
if (!isa<GlobalObject>(LHS) || !isa<GlobalVariable>(RHS) ||
LHS->isThreadLocal() || RHS->isThreadLocal() ||
RHS->getName() != "__ImageBase" || !RHS->hasExternalLinkage() ||
cast<GlobalVariable>(RHS)->hasInitializer() || RHS->hasSection())
return nullptr;
const MCExpr *Res = MCSymbolRefExpr::create(
TM.getSymbol(LHS), MCSymbolRefExpr::VK_COFF_IMGREL32, getContext());
if (Addend != 0)
Res = MCBinaryExpr::createAdd(
Res, MCConstantExpr::create(Addend, getContext()), getContext());
return Res;
}
static std::string APIntToHexString(const APInt &AI) {
unsigned Width = (AI.getBitWidth() / 8) * 2;
std::string HexString = toString(AI, 16, /*Signed=*/false);
llvm::transform(HexString, HexString.begin(), tolower);
unsigned Size = HexString.size();
assert(Width >= Size && "hex string is too large!");
HexString.insert(HexString.begin(), Width - Size, '0');
return HexString;
}
static std::string scalarConstantToHexString(const Constant *C) {
Type *Ty = C->getType();
if (isa<UndefValue>(C)) {
return APIntToHexString(APInt::getZero(Ty->getPrimitiveSizeInBits()));
} else if (const auto *CFP = dyn_cast<ConstantFP>(C)) {
if (CFP->getType()->isFloatingPointTy())
return APIntToHexString(CFP->getValueAPF().bitcastToAPInt());
std::string HexString;
unsigned NumElements =
cast<FixedVectorType>(CFP->getType())->getNumElements();
for (unsigned I = 0; I < NumElements; ++I)
HexString += APIntToHexString(CFP->getValueAPF().bitcastToAPInt());
return HexString;
} else if (const auto *CI = dyn_cast<ConstantInt>(C)) {
if (CI->getType()->isIntegerTy())
return APIntToHexString(CI->getValue());
std::string HexString;
unsigned NumElements =
cast<FixedVectorType>(CI->getType())->getNumElements();
for (unsigned I = 0; I < NumElements; ++I)
HexString += APIntToHexString(CI->getValue());
return HexString;
} else {
unsigned NumElements;
if (auto *VTy = dyn_cast<VectorType>(Ty))
NumElements = cast<FixedVectorType>(VTy)->getNumElements();
else
NumElements = Ty->getArrayNumElements();
std::string HexString;
for (int I = NumElements - 1, E = -1; I != E; --I)
HexString += scalarConstantToHexString(C->getAggregateElement(I));
return HexString;
}
}
MCSection *TargetLoweringObjectFileCOFF::getSectionForConstant(
const DataLayout &DL, SectionKind Kind, const Constant *C, Align &Alignment,
const Function *F) const {
if (Kind.isMergeableConst() && C &&
getContext().getAsmInfo().hasCOFFComdatConstants()) {
// This creates comdat sections with the given symbol name, but unless
// AsmPrinter::GetCPISymbol actually makes the symbol global, the symbol
// will be created with a null storage class, which makes GNU binutils
// error out.
const unsigned Characteristics = COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_LNK_COMDAT;
std::string COMDATSymName;
if (Kind.isMergeableConst4()) {
if (Alignment <= 4) {
COMDATSymName = "__real@" + scalarConstantToHexString(C);
Alignment = Align(4);
}
} else if (Kind.isMergeableConst8()) {
if (Alignment <= 8) {
COMDATSymName = "__real@" + scalarConstantToHexString(C);
Alignment = Align(8);
}
} else if (Kind.isMergeableConst16()) {
// FIXME: These may not be appropriate for non-x86 architectures.
if (Alignment <= 16) {
COMDATSymName = "__xmm@" + scalarConstantToHexString(C);
Alignment = Align(16);
}
} else if (Kind.isMergeableConst32()) {
if (Alignment <= 32) {
COMDATSymName = "__ymm@" + scalarConstantToHexString(C);
Alignment = Align(32);
}
}
if (!COMDATSymName.empty())
return getContext().getCOFFSection(".rdata", Characteristics,
COMDATSymName,
COFF::IMAGE_COMDAT_SELECT_ANY);
}
return TargetLoweringObjectFile::getSectionForConstant(DL, Kind, C, Alignment,
F);
}
//===----------------------------------------------------------------------===//
// Wasm
//===----------------------------------------------------------------------===//
static const Comdat *getWasmComdat(const GlobalValue *GV) {
const Comdat *C = GV->getComdat();
if (!C)
return nullptr;
if (C->getSelectionKind() != Comdat::Any)
report_fatal_error("WebAssembly COMDATs only support "
"SelectionKind::Any, '" + C->getName() + "' cannot be "
"lowered.");
return C;
}
static unsigned getWasmSectionFlags(SectionKind K, bool Retain) {
unsigned Flags = 0;
if (K.isThreadLocal())
Flags |= wasm::WASM_SEG_FLAG_TLS;
if (K.isMergeableCString())
Flags |= wasm::WASM_SEG_FLAG_STRINGS;
if (Retain)
Flags |= wasm::WASM_SEG_FLAG_RETAIN;
// TODO(sbc): Add suport for K.isMergeableConst()
return Flags;
}
void TargetLoweringObjectFileWasm::getModuleMetadata(Module &M) {
SmallVector<GlobalValue *, 4> Vec;
collectUsedGlobalVariables(M, Vec, false);
for (GlobalValue *GV : Vec)
if (auto *GO = dyn_cast<GlobalObject>(GV))
Used.insert(GO);
}
MCSection *TargetLoweringObjectFileWasm::getExplicitSectionGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
// We don't support explict section names for functions in the wasm object
// format. Each function has to be in its own unique section.
if (isa<Function>(GO)) {
return SelectSectionForGlobal(GO, Kind, TM);
}
StringRef Name = GO->getSection();
// Certain data sections we treat as named custom sections rather than
// segments within the data section.
// This could be avoided if all data segements (the wasm sense) were
// represented as their own sections (in the llvm sense).
// TODO(sbc): https://github.com/WebAssembly/tool-conventions/issues/138
if (Name == getInstrProfSectionName(IPSK_covmap, Triple::Wasm,
/*AddSegmentInfo=*/false) ||
Name == getInstrProfSectionName(IPSK_covfun, Triple::Wasm,
/*AddSegmentInfo=*/false) ||
Name == ".llvmbc" || Name == ".llvmcmd")
Kind = SectionKind::getMetadata();
StringRef Group = "";
if (const Comdat *C = getWasmComdat(GO)) {
Group = C->getName();
}
unsigned Flags = getWasmSectionFlags(Kind, Used.count(GO));
MCSectionWasm *Section = getContext().getWasmSection(Name, Kind, Flags, Group,
MCSection::NonUniqueID);
return Section;
}
static MCSectionWasm *
selectWasmSectionForGlobal(MCContext &Ctx, const GlobalObject *GO,
SectionKind Kind, Mangler &Mang,
const TargetMachine &TM, bool EmitUniqueSection,
unsigned *NextUniqueID, bool Retain) {
StringRef Group = "";
if (const Comdat *C = getWasmComdat(GO)) {
Group = C->getName();
}
bool UniqueSectionNames = TM.getUniqueSectionNames();
SmallString<128> Name = getSectionPrefixForGlobal(Kind, /*IsLarge=*/false);
if (const auto *F = dyn_cast<Function>(GO)) {
const auto &OptionalPrefix = F->getSectionPrefix();
if (OptionalPrefix)
raw_svector_ostream(Name) << '.' << *OptionalPrefix;
}
if (EmitUniqueSection && UniqueSectionNames) {
Name.push_back('.');
TM.getNameWithPrefix(Name, GO, Mang, true);
}
unsigned UniqueID = MCSection::NonUniqueID;
if (EmitUniqueSection && !UniqueSectionNames) {
UniqueID = *NextUniqueID;
(*NextUniqueID)++;
}
unsigned Flags = getWasmSectionFlags(Kind, Retain);
return Ctx.getWasmSection(Name, Kind, Flags, Group, UniqueID);
}
MCSection *TargetLoweringObjectFileWasm::SelectSectionForGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
if (Kind.isCommon())
report_fatal_error("mergable sections not supported yet on wasm");
// If we have -ffunction-section or -fdata-section then we should emit the
// global value to a uniqued section specifically for it.
bool EmitUniqueSection = false;
if (Kind.isText())
EmitUniqueSection = TM.getFunctionSections();
else
EmitUniqueSection = TM.getDataSections();
EmitUniqueSection |= GO->hasComdat();
bool Retain = Used.count(GO);
EmitUniqueSection |= Retain;
return selectWasmSectionForGlobal(getContext(), GO, Kind, getMangler(), TM,
EmitUniqueSection, &NextUniqueID, Retain);
}
bool TargetLoweringObjectFileWasm::shouldPutJumpTableInFunctionSection(
bool UsesLabelDifference, const Function &F) const {
// We can always create relative relocations, so use another section
// that can be marked non-executable.
return false;
}
void TargetLoweringObjectFileWasm::InitializeWasm() {
StaticCtorSection =
getContext().getWasmSection(".init_array", SectionKind::getData());
// We don't use PersonalityEncoding and LSDAEncoding because we don't emit
// .cfi directives. We use TTypeEncoding to encode typeinfo global variables.
TTypeEncoding = dwarf::DW_EH_PE_absptr;
}
MCSection *TargetLoweringObjectFileWasm::getStaticCtorSection(
unsigned Priority, const MCSymbol *KeySym) const {
return Priority == UINT16_MAX ?
StaticCtorSection :
getContext().getWasmSection(".init_array." + utostr(Priority),
SectionKind::getData());
}
MCSection *TargetLoweringObjectFileWasm::getStaticDtorSection(
unsigned Priority, const MCSymbol *KeySym) const {
report_fatal_error("@llvm.global_dtors should have been lowered already");
}
//===----------------------------------------------------------------------===//
// XCOFF
//===----------------------------------------------------------------------===//
bool TargetLoweringObjectFileXCOFF::ShouldEmitEHBlock(
const MachineFunction *MF) {
if (!MF->getLandingPads().empty())
return true;
const Function &F = MF->getFunction();
if (!F.hasPersonalityFn() || !F.needsUnwindTableEntry())
return false;
const GlobalValue *Per =
dyn_cast<GlobalValue>(F.getPersonalityFn()->stripPointerCasts());
assert(Per && "Personality routine is not a GlobalValue type.");
if (isNoOpWithoutInvoke(classifyEHPersonality(Per)))
return false;
return true;
}
bool TargetLoweringObjectFileXCOFF::ShouldSetSSPCanaryBitInTB(
const MachineFunction *MF) {
const Function &F = MF->getFunction();
if (!F.hasStackProtectorFnAttr())
return false;
// FIXME: check presence of canary word
// There are cases that the stack protectors are not really inserted even if
// the attributes are on.
return true;
}
MCSymbol *
TargetLoweringObjectFileXCOFF::getEHInfoTableSymbol(const MachineFunction *MF) {
auto *EHInfoSym =
static_cast<MCSymbolXCOFF *>(MF->getContext().getOrCreateSymbol(
"__ehinfo." + Twine(MF->getFunctionNumber())));
EHInfoSym->setEHInfo();
return EHInfoSym;
}
MCSymbol *
TargetLoweringObjectFileXCOFF::getTargetSymbol(const GlobalValue *GV,
const TargetMachine &TM) const {
// We always use a qualname symbol for a GV that represents
// a declaration, a function descriptor, or a common symbol. An IFunc is
// lowered as a special trampoline function which has an entry point and a
// descriptor.
// If a GV represents a GlobalVariable and -fdata-sections is enabled, we
// also return a qualname so that a label symbol could be avoided.
// It is inherently ambiguous when the GO represents the address of a
// function, as the GO could either represent a function descriptor or a
// function entry point. We choose to always return a function descriptor
// here.
if (const GlobalObject *GO = dyn_cast<GlobalObject>(GV)) {
if (GO->isDeclarationForLinker())
return static_cast<const MCSectionXCOFF *>(
getSectionForExternalReference(GO, TM))
->getQualNameSymbol();
if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV))
if (GVar->hasAttribute("toc-data"))
return static_cast<const MCSectionXCOFF *>(
SectionForGlobal(GVar, SectionKind::getData(), TM))
->getQualNameSymbol();
if (isa<GlobalIFunc>(GO))
return static_cast<const MCSectionXCOFF *>(
getSectionForFunctionDescriptor(GO, TM))
->getQualNameSymbol();
SectionKind GOKind = getKindForGlobal(GO, TM);
if (GOKind.isText())
return static_cast<const MCSectionXCOFF *>(
getSectionForFunctionDescriptor(cast<Function>(GO), TM))
->getQualNameSymbol();
if ((TM.getDataSections() && !GO->hasSection()) || GO->hasCommonLinkage() ||
GOKind.isBSSLocal() || GOKind.isThreadBSSLocal())
return static_cast<const MCSectionXCOFF *>(
SectionForGlobal(GO, GOKind, TM))
->getQualNameSymbol();
}
// For all other cases, fall back to getSymbol to return the unqualified name.
return nullptr;
}
MCSection *TargetLoweringObjectFileXCOFF::getExplicitSectionGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
if (!GO->hasSection())
report_fatal_error("#pragma clang section is not yet supported");
StringRef SectionName = GO->getSection();
// Handle the XCOFF::TD case first, then deal with the rest.
if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GO))
if (GVar->hasAttribute("toc-data"))
return getContext().getXCOFFSection(
SectionName, Kind,
XCOFF::CsectProperties(/*MappingClass*/ XCOFF::XMC_TD, XCOFF::XTY_SD),
/* MultiSymbolsAllowed*/ true);
XCOFF::StorageMappingClass MappingClass;
if (Kind.isText())
MappingClass = XCOFF::XMC_PR;
else if (Kind.isData() || Kind.isBSS())
MappingClass = XCOFF::XMC_RW;
else if (Kind.isReadOnlyWithRel())
MappingClass =
TM.Options.XCOFFReadOnlyPointers ? XCOFF::XMC_RO : XCOFF::XMC_RW;
else if (Kind.isReadOnly())
MappingClass = XCOFF::XMC_RO;
else
report_fatal_error("XCOFF other section types not yet implemented.");
return getContext().getXCOFFSection(
SectionName, Kind, XCOFF::CsectProperties(MappingClass, XCOFF::XTY_SD),
/* MultiSymbolsAllowed*/ true);
}
MCSection *TargetLoweringObjectFileXCOFF::getSectionForExternalReference(
const GlobalObject *GO, const TargetMachine &TM) const {
assert(GO->isDeclarationForLinker() &&
"Tried to get ER section for a defined global.");
SmallString<128> Name;
getNameWithPrefix(Name, GO, TM);
// AIX TLS local-dynamic does not need the external reference for the
// "_$TLSML" symbol.
if (GO->getThreadLocalMode() == GlobalVariable::LocalDynamicTLSModel &&
GO->hasName() && GO->getName() == "_$TLSML") {
return getContext().getXCOFFSection(
Name, SectionKind::getData(),
XCOFF::CsectProperties(XCOFF::XMC_TC, XCOFF::XTY_SD));
}
XCOFF::StorageMappingClass SMC =
isa<Function>(GO) ? XCOFF::XMC_DS : XCOFF::XMC_UA;
if (GO->isThreadLocal())
SMC = XCOFF::XMC_UL;
if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GO))
if (GVar->hasAttribute("toc-data"))
SMC = XCOFF::XMC_TD;
// Externals go into a csect of type ER.
return getContext().getXCOFFSection(
Name, SectionKind::getMetadata(),
XCOFF::CsectProperties(SMC, XCOFF::XTY_ER));
}
MCSection *TargetLoweringObjectFileXCOFF::SelectSectionForGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
// Handle the XCOFF::TD case first, then deal with the rest.
if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GO))
if (GVar->hasAttribute("toc-data")) {
SmallString<128> Name;
getNameWithPrefix(Name, GO, TM);
XCOFF::SymbolType symType =
GO->hasCommonLinkage() ? XCOFF::XTY_CM : XCOFF::XTY_SD;
return getContext().getXCOFFSection(
Name, Kind, XCOFF::CsectProperties(XCOFF::XMC_TD, symType),
/* MultiSymbolsAllowed*/ true);
}
// Common symbols go into a csect with matching name which will get mapped
// into the .bss section.
// Zero-initialized local TLS symbols go into a csect with matching name which
// will get mapped into the .tbss section.
if (Kind.isBSSLocal() || GO->hasCommonLinkage() || Kind.isThreadBSSLocal()) {
SmallString<128> Name;
getNameWithPrefix(Name, GO, TM);
XCOFF::StorageMappingClass SMC = Kind.isBSSLocal() ? XCOFF::XMC_BS
: Kind.isCommon() ? XCOFF::XMC_RW
: XCOFF::XMC_UL;
return getContext().getXCOFFSection(
Name, Kind, XCOFF::CsectProperties(SMC, XCOFF::XTY_CM));
}
if (Kind.isText()) {
if (TM.getFunctionSections()) {
return static_cast<const MCSymbolXCOFF *>(
getFunctionEntryPointSymbol(GO, TM))
->getRepresentedCsect();
}
return TextSection;
}
if (TM.Options.XCOFFReadOnlyPointers && Kind.isReadOnlyWithRel()) {
if (!TM.getDataSections())
report_fatal_error(
"ReadOnlyPointers is supported only if data sections is turned on");
SmallString<128> Name;
getNameWithPrefix(Name, GO, TM);
return getContext().getXCOFFSection(
Name, SectionKind::getReadOnly(),
XCOFF::CsectProperties(XCOFF::XMC_RO, XCOFF::XTY_SD));
}
// For BSS kind, zero initialized data must be emitted to the .data section
// because external linkage control sections that get mapped to the .bss
// section will be linked as tentative definitions, which is only appropriate
// for SectionKind::Common.
if (Kind.isData() || Kind.isReadOnlyWithRel() || Kind.isBSS()) {
if (TM.getDataSections()) {
SmallString<128> Name;
getNameWithPrefix(Name, GO, TM);
return getContext().getXCOFFSection(
Name, SectionKind::getData(),
XCOFF::CsectProperties(XCOFF::XMC_RW, XCOFF::XTY_SD));
}
return DataSection;
}
if (Kind.isReadOnly()) {
if (TM.getDataSections()) {
SmallString<128> Name;
getNameWithPrefix(Name, GO, TM);
return getContext().getXCOFFSection(
Name, SectionKind::getReadOnly(),
XCOFF::CsectProperties(XCOFF::XMC_RO, XCOFF::XTY_SD));
}
return ReadOnlySection;
}
// External/weak TLS data and initialized local TLS data are not eligible
// to be put into common csect. If data sections are enabled, thread
// data are emitted into separate sections. Otherwise, thread data
// are emitted into the .tdata section.
if (Kind.isThreadLocal()) {
if (TM.getDataSections()) {
SmallString<128> Name;
getNameWithPrefix(Name, GO, TM);
return getContext().getXCOFFSection(
Name, Kind, XCOFF::CsectProperties(XCOFF::XMC_TL, XCOFF::XTY_SD));
}
return TLSDataSection;
}
report_fatal_error("XCOFF other section types not yet implemented.");
}
MCSection *TargetLoweringObjectFileXCOFF::getSectionForJumpTable(
const Function &F, const TargetMachine &TM) const {
assert (!F.getComdat() && "Comdat not supported on XCOFF.");
if (!TM.getFunctionSections())
return ReadOnlySection;
// If the function can be removed, produce a unique section so that
// the table doesn't prevent the removal.
SmallString<128> NameStr(".rodata.jmp..");
getNameWithPrefix(NameStr, &F, TM);
return getContext().getXCOFFSection(
NameStr, SectionKind::getReadOnly(),
XCOFF::CsectProperties(XCOFF::XMC_RO, XCOFF::XTY_SD));
}
bool TargetLoweringObjectFileXCOFF::shouldPutJumpTableInFunctionSection(
bool UsesLabelDifference, const Function &F) const {
return false;
}
/// Given a mergeable constant with the specified size and relocation
/// information, return a section that it should be placed in.
MCSection *TargetLoweringObjectFileXCOFF::getSectionForConstant(
const DataLayout &DL, SectionKind Kind, const Constant *C, Align &Alignment,
const Function *F) const {
// TODO: Enable emiting constant pool to unique sections when we support it.
if (Alignment > Align(16))
report_fatal_error("Alignments greater than 16 not yet supported.");
if (Alignment == Align(8)) {
assert(ReadOnly8Section && "Section should always be initialized.");
return ReadOnly8Section;
}
if (Alignment == Align(16)) {
assert(ReadOnly16Section && "Section should always be initialized.");
return ReadOnly16Section;
}
return ReadOnlySection;
}
void TargetLoweringObjectFileXCOFF::Initialize(MCContext &Ctx,
const TargetMachine &TgtM) {
TargetLoweringObjectFile::Initialize(Ctx, TgtM);
TTypeEncoding =
dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_datarel |
(TgtM.getTargetTriple().isArch32Bit() ? dwarf::DW_EH_PE_sdata4
: dwarf::DW_EH_PE_sdata8);
PersonalityEncoding = 0;
LSDAEncoding = 0;
CallSiteEncoding = dwarf::DW_EH_PE_udata4;
// AIX debug for thread local location is not ready. And for integrated as
// mode, the relocatable address for the thread local variable will cause
// linker error. So disable the location attribute generation for thread local
// variables for now.
// FIXME: when TLS debug on AIX is ready, remove this setting.
SupportDebugThreadLocalLocation = false;
}
MCSection *TargetLoweringObjectFileXCOFF::getStaticCtorSection(
unsigned Priority, const MCSymbol *KeySym) const {
report_fatal_error("no static constructor section on AIX");
}
MCSection *TargetLoweringObjectFileXCOFF::getStaticDtorSection(
unsigned Priority, const MCSymbol *KeySym) const {
report_fatal_error("no static destructor section on AIX");
}
XCOFF::StorageClass
TargetLoweringObjectFileXCOFF::getStorageClassForGlobal(const GlobalValue *GV) {
assert(!isa<GlobalIFunc>(GV) && "GlobalIFunc is not supported on AIX.");
switch (GV->getLinkage()) {
case GlobalValue::InternalLinkage:
case GlobalValue::PrivateLinkage:
return XCOFF::C_HIDEXT;
case GlobalValue::ExternalLinkage:
case GlobalValue::CommonLinkage:
case GlobalValue::AvailableExternallyLinkage:
return XCOFF::C_EXT;
case GlobalValue::ExternalWeakLinkage:
case GlobalValue::LinkOnceAnyLinkage:
case GlobalValue::LinkOnceODRLinkage:
case GlobalValue::WeakAnyLinkage:
case GlobalValue::WeakODRLinkage:
return XCOFF::C_WEAKEXT;
case GlobalValue::AppendingLinkage:
report_fatal_error(
"There is no mapping that implements AppendingLinkage for XCOFF.");
}
llvm_unreachable("Unknown linkage type!");
}
MCSymbol *TargetLoweringObjectFileXCOFF::getFunctionEntryPointSymbol(
const GlobalValue *Func, const TargetMachine &TM) const {
assert((isa<Function>(Func) || isa<GlobalIFunc>(Func) ||
(isa<GlobalAlias>(Func) &&
isa_and_nonnull<Function>(
cast<GlobalAlias>(Func)->getAliaseeObject()))) &&
"Func must be a function or an alias which has a function as base "
"object.");
SmallString<128> NameStr;
NameStr.push_back('.');
getNameWithPrefix(NameStr, Func, TM);
// When -function-sections is enabled and explicit section is not specified,
// it's not necessary to emit function entry point label any more. We will use
// function entry point csect instead. And for function delcarations, the
// undefined symbols gets treated as csect with XTY_ER property.
if (((TM.getFunctionSections() && !Func->hasSection()) ||
Func->isDeclarationForLinker()) &&
(isa<Function>(Func) || isa<GlobalIFunc>(Func))) {
return getContext()
.getXCOFFSection(
NameStr, SectionKind::getText(),
XCOFF::CsectProperties(XCOFF::XMC_PR, Func->isDeclarationForLinker()
? XCOFF::XTY_ER
: XCOFF::XTY_SD))
->getQualNameSymbol();
}
return getContext().getOrCreateSymbol(NameStr);
}
MCSection *TargetLoweringObjectFileXCOFF::getSectionForFunctionDescriptor(
const GlobalObject *F, const TargetMachine &TM) const {
assert((isa<Function>(F) || isa<GlobalIFunc>(F)) &&
"F must be a function or ifunc object.");
SmallString<128> NameStr;
getNameWithPrefix(NameStr, F, TM);
return getContext().getXCOFFSection(
NameStr, SectionKind::getData(),
XCOFF::CsectProperties(XCOFF::XMC_DS, XCOFF::XTY_SD));
}
MCSection *TargetLoweringObjectFileXCOFF::getSectionForTOCEntry(
const MCSymbol *Sym, const TargetMachine &TM) const {
const XCOFF::StorageMappingClass SMC = [](const MCSymbol *Sym,
const TargetMachine &TM) {
auto *XSym = static_cast<const MCSymbolXCOFF *>(Sym);
// The "_$TLSML" symbol for TLS local-dynamic mode requires XMC_TC,
// otherwise the AIX assembler will complain.
if (XSym->getSymbolTableName() == "_$TLSML")
return XCOFF::XMC_TC;
// Use large code model toc entries for ehinfo symbols as they are
// never referenced directly. The runtime loads their TOC entry
// addresses from the trace-back table.
if (XSym->isEHInfo())
return XCOFF::XMC_TE;
// If the symbol does not have a code model specified use the module value.
if (!XSym->hasPerSymbolCodeModel())
return TM.getCodeModel() == CodeModel::Large ? XCOFF::XMC_TE
: XCOFF::XMC_TC;
return XSym->getPerSymbolCodeModel() == MCSymbolXCOFF::CM_Large
? XCOFF::XMC_TE
: XCOFF::XMC_TC;
}(Sym, TM);
return getContext().getXCOFFSection(
static_cast<const MCSymbolXCOFF *>(Sym)->getSymbolTableName(),
SectionKind::getData(), XCOFF::CsectProperties(SMC, XCOFF::XTY_SD));
}
MCSection *TargetLoweringObjectFileXCOFF::getSectionForLSDA(
const Function &F, const MCSymbol &FnSym, const TargetMachine &TM) const {
auto *LSDA = static_cast<MCSectionXCOFF *>(LSDASection);
if (TM.getFunctionSections()) {
// If option -ffunction-sections is on, append the function name to the
// name of the LSDA csect so that each function has its own LSDA csect.
// This helps the linker to garbage-collect EH info of unused functions.
SmallString<128> NameStr = LSDA->getName();
raw_svector_ostream(NameStr) << '.' << F.getName();
LSDA = getContext().getXCOFFSection(NameStr, LSDA->getKind(),
LSDA->getCsectProp());
}
return LSDA;
}
//===----------------------------------------------------------------------===//
// GOFF
//===----------------------------------------------------------------------===//
TargetLoweringObjectFileGOFF::TargetLoweringObjectFileGOFF() = default;
void TargetLoweringObjectFileGOFF::getModuleMetadata(Module &M) {
// Construct the default names for the root SD and the ADA PR symbol.
StringRef FileName = sys::path::stem(M.getSourceFileName());
if (FileName.size() > 1 && FileName.starts_with('<') &&
FileName.ends_with('>'))
FileName = FileName.substr(1, FileName.size() - 2);
DefaultRootSDName = Twine(FileName).concat("#C").str();
DefaultADAPRName = Twine(FileName).concat("#S").str();
MCSectionGOFF *RootSD =
static_cast<MCSectionGOFF *>(TextSection)->getParent();
MCSectionGOFF *ADAPR = static_cast<MCSectionGOFF *>(ADASection);
RootSD->setName(DefaultRootSDName);
ADAPR->setName(DefaultADAPRName);
// Initialize the label for the text section.
MCSymbolGOFF *TextLD = static_cast<MCSymbolGOFF *>(
getContext().getOrCreateSymbol(RootSD->getName()));
TextLD->setCodeData(GOFF::ESD_EXE_CODE);
TextLD->setLinkage(GOFF::ESD_LT_XPLink);
TextLD->setExternal(false);
TextLD->setWeak(false);
TextLD->setADA(ADAPR);
TextSection->setBeginSymbol(TextLD);
// Initialize the label for the ADA section.
MCSymbolGOFF *ADASym = static_cast<MCSymbolGOFF *>(
getContext().getOrCreateSymbol(ADAPR->getName()));
ADAPR->setBeginSymbol(ADASym);
}
bool TargetLoweringObjectFileGOFF::shouldPutJumpTableInFunctionSection(
bool UsesLabelDifference, const Function &F) const {
return true;
}
MCSection *TargetLoweringObjectFileGOFF::getExplicitSectionGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
return SelectSectionForGlobal(GO, Kind, TM);
}
MCSection *TargetLoweringObjectFileGOFF::getSectionForLSDA(
const Function &F, const MCSymbol &FnSym, const TargetMachine &TM) const {
std::string Name = ".gcc_exception_table." + F.getName().str();
MCSectionGOFF *WSA = getContext().getGOFFSection(
SectionKind::getMetadata(), GOFF::CLASS_WSA,
GOFF::EDAttr{false, GOFF::ESD_RMODE_64, GOFF::ESD_NS_Parts,
GOFF::ESD_TS_ByteOriented, GOFF::ESD_BA_Merge,
GOFF::ESD_LB_Initial, GOFF::ESD_RQ_0,
GOFF::ESD_ALIGN_Fullword, 0},
static_cast<MCSectionGOFF *>(TextSection)->getParent());
return getContext().getGOFFSection(SectionKind::getData(), Name,
GOFF::PRAttr{true, GOFF::ESD_EXE_DATA,
GOFF::ESD_LT_XPLink,
GOFF::ESD_BSC_Section, 0},
WSA);
}
MCSection *TargetLoweringObjectFileGOFF::SelectSectionForGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
auto *Symbol = TM.getSymbol(GO);
if (Kind.isBSS() || Kind.isData()) {
GOFF::ESDBindingScope PRBindingScope =
GO->hasExternalLinkage()
? (GO->hasDefaultVisibility() ? GOFF::ESD_BSC_ImportExport
: GOFF::ESD_BSC_Library)
: GOFF::ESD_BSC_Section;
GOFF::ESDBindingScope SDBindingScope =
PRBindingScope == GOFF::ESD_BSC_Section ? GOFF::ESD_BSC_Section
: GOFF::ESD_BSC_Unspecified;
MaybeAlign Alignment;
if (auto *F = dyn_cast<Function>(GO))
Alignment = F->getAlign();
else if (auto *V = dyn_cast<GlobalVariable>(GO))
Alignment = V->getAlign();
GOFF::ESDAlignment Align =
Alignment ? static_cast<GOFF::ESDAlignment>(Log2(*Alignment))
: GOFF::ESD_ALIGN_Doubleword;
MCSectionGOFF *SD = getContext().getGOFFSection(
SectionKind::getMetadata(), Symbol->getName(),
GOFF::SDAttr{GOFF::ESD_TA_Unspecified, SDBindingScope});
MCSectionGOFF *ED = getContext().getGOFFSection(
SectionKind::getMetadata(), GOFF::CLASS_WSA,
GOFF::EDAttr{false, GOFF::ESD_RMODE_64, GOFF::ESD_NS_Parts,
GOFF::ESD_TS_ByteOriented, GOFF::ESD_BA_Merge,
GOFF::ESD_LB_Deferred, GOFF::ESD_RQ_0, Align, 0},
SD);
return getContext().getGOFFSection(Kind, Symbol->getName(),
GOFF::PRAttr{false, GOFF::ESD_EXE_DATA,
GOFF::ESD_LT_XPLink,
PRBindingScope, 0},
ED);
}
return TextSection;
}
MCSection *
TargetLoweringObjectFileGOFF::getStaticXtorSection(unsigned Priority) const {
// XL C/C++ compilers on z/OS support priorities from min-int to max-int, with
// sinit as source priority 0. For clang, sinit has source priority 65535.
// For GOFF, the priority sortkey field is an unsigned value. So, we
// add min-int to get sorting to work properly but also subtract the
// clang sinit (65535) value so internally xl sinit and clang sinit have
// the same unsigned GOFF priority sortkey field value (i.e. 0x80000000).
static constexpr const uint32_t ClangDefaultSinitPriority = 65535;
uint32_t Prio = Priority + (0x80000000 - ClangDefaultSinitPriority);
std::string Name(".xtor");
if (Priority != ClangDefaultSinitPriority)
Name = llvm::Twine(Name).concat(".").concat(llvm::utostr(Priority)).str();
MCContext &Ctx = getContext();
MCSectionGOFF *SInit = Ctx.getGOFFSection(
SectionKind::getMetadata(), GOFF::CLASS_SINIT,
GOFF::EDAttr{false, GOFF::ESD_RMODE_64, GOFF::ESD_NS_Parts,
GOFF::ESD_TS_ByteOriented, GOFF::ESD_BA_Merge,
GOFF::ESD_LB_Initial, GOFF::ESD_RQ_0,
GOFF::ESD_ALIGN_Doubleword},
static_cast<const MCSectionGOFF *>(TextSection)->getParent());
MCSectionGOFF *Xtor = Ctx.getGOFFSection(
SectionKind::getData(), Name,
GOFF::PRAttr{true, GOFF::ESD_EXE_DATA, GOFF::ESD_LT_XPLink,
GOFF::ESD_BSC_Section, Prio},
SInit);
return Xtor;
}