RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2024-10-19 11:02:59 +02:00
Code Issues Projects Releases Wiki Activity
0606b4495b
llvm-mirror/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
Petr Hosek e5a6554cdf [InstrProfiling] Use nobits as __llvm_prf_cnts section type in ELF 
This can reduce the binary size because counters will no longer occupy
space in the binary, instead they will be allocated by dynamic linker.

Differential Revision: https://reviews.llvm.org/D97110
2021-02-20 14:20:33 -08:00

2389 lines
90 KiB
C++
Raw Blame History

//===- 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/ADT/Triple.h"
#include "llvm/BinaryFormat/COFF.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/BinaryFormat/MachO.h"
#include "llvm/CodeGen/BasicBlockSectionUtils.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunction.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/PseudoProbe.h"
#include "llvm/IR/Type.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCSectionCOFF.h"
#include "llvm/MC/MCSectionELF.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/MCValue.h"
#include "llvm/MC/SectionKind.h"
#include "llvm/ProfileData/InstrProf.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include <cassert>
#include <string>
using namespace llvm;
using namespace dwarf;
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
//===----------------------------------------------------------------------===//
TargetLoweringObjectFileELF::TargetLoweringObjectFileELF()
: TargetLoweringObjectFile() {
SupportDSOLocalEquivalentLowering = true;
}
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
LLVM_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_sdata8 : dwarf::DW_EH_PE_sdata4);
} 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.
if (isPositionIndependent()) {
// ILP32 uses sdata4 instead of sdata8
if (TgtM.getTargetTriple().getEnvironment() == Triple::GNUILP32) {
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_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata8;
LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8;
TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
dwarf::DW_EH_PE_sdata8;
}
} else {
PersonalityEncoding = dwarf::DW_EH_PE_absptr;
LSDAEncoding = dwarf::DW_EH_PE_absptr;
TTypeEncoding = dwarf::DW_EH_PE_absptr;
}
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;
// We don't support PC-relative LSDA references in GAS so we use the default
// DW_EH_PE_absptr for those.
// 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 (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:
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;
default:
break;
}
}
void TargetLoweringObjectFileELF::emitModuleMetadata(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);
}
}
}
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);
}
}
if (NamedMDNode *FuncInfo = M.getNamedMetadata(PseudoProbeDescMetadataName)) {
// Emit a descriptor for every function including functions that have an
// available external linkage. We may not want this for imported functions
// that has code in another thinLTO module but we don't have a good way to
// tell them apart from inline functions defined in header files. Therefore
// we put each descriptor in a separate comdat section and rely on the
// linker to deduplicate.
for (const auto *Operand : FuncInfo->operands()) {
const auto *MD = cast<MDNode>(Operand);
auto *GUID = mdconst::dyn_extract<ConstantInt>(MD->getOperand(0));
auto *Hash = mdconst::dyn_extract<ConstantInt>(MD->getOperand(1));
auto *Name = cast<MDString>(MD->getOperand(2));
auto *S = C.getObjectFileInfo()->getPseudoProbeDescSection(
TM->getFunctionSections() ? Name->getString() : StringRef());
Streamer.SwitchSection(S);
Streamer.emitInt64(GUID->getZExtValue());
Streamer.emitInt64(Hash->getZExtValue());
Streamer.emitULEB128IntValue(Name->getString().size());
Streamer.emitBytes(Name->getString());
}
}
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);
}
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 {
SmallString<64> NameData("DW.ref.");
NameData += Sym->getName();
MCSymbolELF *Label =
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).value());
Streamer.emitSymbolAttribute(Label, MCSA_ELF_TypeObject);
const MCExpr *E = MCConstantExpr::create(Size, getContext());
Streamer.emitELFSize(Label, E);
Streamer.emitLabel(Label);
Streamer.emitSymbolValue(Sym, Size);
}
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 == ".llvmbc" || Name == ".llvmcmd")
return SectionKind::getMetadata();
if (Name == getInstrProfSectionName(IPSK_cnts, Triple::ELF,
/*AddSegmentInfo=*/false))
return SectionKind::getBSS();
if (Name.empty() || Name[0] != '.') return K;
// Default implementation based on some magic section names.
if (Name == ".bss" ||
Name.startswith(".bss.") ||
Name.startswith(".gnu.linkonce.b.") ||
Name.startswith(".llvm.linkonce.b.") ||
Name == ".sbss" ||
Name.startswith(".sbss.") ||
Name.startswith(".gnu.linkonce.sb.") ||
Name.startswith(".llvm.linkonce.sb."))
return SectionKind::getBSS();
if (Name == ".tdata" ||
Name.startswith(".tdata.") ||
Name.startswith(".gnu.linkonce.td.") ||
Name.startswith(".llvm.linkonce.td."))
return SectionKind::getThreadData();
if (Name == ".tbss" ||
Name.startswith(".tbss.") ||
Name.startswith(".gnu.linkonce.tb.") ||
Name.startswith(".llvm.linkonce.tb."))
return SectionKind::getThreadBSS();
return K;
}
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.startswith(".note"))
return ELF::SHT_NOTE;
if (Name == ".init_array")
return ELF::SHT_INIT_ARRAY;
if (Name == ".fini_array")
return ELF::SHT_FINI_ARRAY;
if (Name == ".preinit_array")
return ELF::SHT_PREINIT_ARRAY;
if (K.isBSS() || K.isThreadBSS())
return ELF::SHT_NOBITS;
return ELF::SHT_PROGBITS;
}
static unsigned getELFSectionFlags(SectionKind K) {
unsigned Flags = 0;
if (!K.isMetadata())
Flags |= ELF::SHF_ALLOC;
if (K.isText())
Flags |= ELF::SHF_EXECINSTR;
if (K.isExecuteOnly())
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::NoDuplicates)
report_fatal_error("ELF COMDATs only support SelectionKind::Any and "
"SelectionKind::NoDuplicates, '" + 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;
const MDOperand &Op = MD->getOperand(0);
if (!Op.get())
return nullptr;
auto *VM = dyn_cast<ValueAsMetadata>(Op);
if (!VM)
report_fatal_error("MD_associated operand is not ValueAsMetadata");
auto *OtherGV = dyn_cast<GlobalValue>(VM->getValue());
return OtherGV ? dyn_cast<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) {
if (Kind.isText())
return ".text";
if (Kind.isReadOnly())
return ".rodata";
if (Kind.isBSS())
return ".bss";
if (Kind.isThreadData())
return ".tdata";
if (Kind.isThreadBSS())
return ".tbss";
if (Kind.isData())
return ".data";
if (Kind.isReadOnlyWithRel())
return ".data.rel.ro";
llvm_unreachable("Unknown section kind");
}
static SmallString<128>
getELFSectionNameForGlobal(const GlobalObject *GO, SectionKind Kind,
Mangler &Mang, const TargetMachine &TM,
unsigned EntrySize, bool UniqueSectionName) {
SmallString<128> Name;
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->getParent()->getDataLayout().getPreferredAlign(
cast<GlobalVariable>(GO));
std::string SizeSpec = ".rodata.str" + utostr(EntrySize) + ".";
Name = SizeSpec + utostr(Alignment.value());
} else if (Kind.isMergeableConst()) {
Name = ".rodata.cst";
Name += utostr(EntrySize);
} else {
Name = getSectionPrefixForGlobal(Kind);
}
bool HasPrefix = false;
if (const auto *F = dyn_cast<Function>(GO)) {
if (Optional<StringRef> Prefix = F->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,
DiagnosticSeverity Severity = DS_Error)
: DiagnosticInfo(DK_Lowering, Severity), Msg(DiagMsg) {}
void print(DiagnosticPrinter &DP) const override { DP << Msg; }
};
}
MCSection *TargetLoweringObjectFileELF::getExplicitSectionGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
StringRef SectionName = GO->getSection();
// 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()) {
SectionName = Attrs.getAttribute("bss-section").getValueAsString();
} else if (Attrs.hasAttribute("rodata-section") && Kind.isReadOnly()) {
SectionName = Attrs.getAttribute("rodata-section").getValueAsString();
} else if (Attrs.hasAttribute("relro-section") && Kind.isReadOnlyWithRel()) {
SectionName = Attrs.getAttribute("relro-section").getValueAsString();
} else if (Attrs.hasAttribute("data-section") && Kind.isData()) {
SectionName = Attrs.getAttribute("data-section").getValueAsString();
}
}
const Function *F = dyn_cast<Function>(GO);
if (F && F->hasFnAttribute("implicit-section-name")) {
SectionName = F->getFnAttribute("implicit-section-name").getValueAsString();
}
// Infer section flags from the section name if we can.
Kind = getELFKindForNamedSection(SectionName, Kind);
StringRef Group = "";
bool IsComdat = false;
unsigned Flags = getELFSectionFlags(Kind);
if (const Comdat *C = getELFComdat(GO)) {
Group = C->getName();
IsComdat = C->getSelectionKind() == Comdat::Any;
Flags |= ELF::SHF_GROUP;
}
unsigned EntrySize = getEntrySizeForKind(Kind);
// A section can have at most one associated section. Put each global with
// MD_associated in a unique section.
unsigned UniqueID = MCContext::GenericSectionID;
const MCSymbolELF *LinkedToSym = getLinkedToSymbol(GO, TM);
if (GO->getMetadata(LLVMContext::MD_associated)) {
UniqueID = NextUniqueID++;
Flags |= ELF::SHF_LINK_ORDER;
} else {
if (getContext().getAsmInfo()->useIntegratedAssembler() ||
getContext().getAsmInfo()->binutilsIsAtLeast(2, 35)) {
// Symbols must be placed into sections with compatible entry
// sizes. Generate unique sections for symbols that have not
// been assigned to compatible sections.
if (Flags & ELF::SHF_MERGE) {
auto maybeID = getContext().getELFUniqueIDForEntsize(SectionName, Flags,
EntrySize);
if (maybeID)
UniqueID = *maybeID;
else {
// 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, getMangler(), TM, EntrySize, false);
if (!(getContext().isELFImplicitMergeableSectionNamePrefix(
SectionName) &&
SectionName.startswith(ImplicitSectionNameStem)))
UniqueID = NextUniqueID++;
}
} else {
// We need to unique the section if the user has explicity
// assigned a non-mergeable symbol to a section name for
// a generic mergeable section.
if (getContext().isELFGenericMergeableSection(SectionName)) {
auto maybeID = getContext().getELFUniqueIDForEntsize(
SectionName, Flags, EntrySize);
UniqueID = maybeID ? *maybeID : NextUniqueID++;
}
}
} else {
// 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 avalible until bintuils
// version 2.35 (https://sourceware.org/bugzilla/show_bug.cgi?id=25380).
Flags &= ~ELF::SHF_MERGE;
EntrySize = 0;
}
}
MCSectionELF *Section = getContext().getELFSection(
SectionName, getELFSectionType(SectionName, Kind), 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 (!(getContext().getAsmInfo()->useIntegratedAssembler() ||
getContext().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;
}
static MCSectionELF *selectELFSectionForGlobal(
MCContext &Ctx, const GlobalObject *GO, SectionKind Kind, Mangler &Mang,
const TargetMachine &TM, bool EmitUniqueSection, unsigned Flags,
unsigned *NextUniqueID, const MCSymbolELF *AssociatedSymbol) {
StringRef Group = "";
bool IsComdat = false;
if (const Comdat *C = getELFComdat(GO)) {
Flags |= ELF::SHF_GROUP;
Group = C->getName();
IsComdat = C->getSelectionKind() == Comdat::Any;
}
// Get the section entry size based on the kind.
unsigned EntrySize = getEntrySizeForKind(Kind);
bool UniqueSectionName = false;
unsigned UniqueID = MCContext::GenericSectionID;
if (EmitUniqueSection) {
if (TM.getUniqueSectionNames()) {
UniqueSectionName = true;
} else {
UniqueID = *NextUniqueID;
(*NextUniqueID)++;
}
}
SmallString<128> Name = getELFSectionNameForGlobal(
GO, Kind, Mang, TM, EntrySize, UniqueSectionName);
// Use 0 as the unique ID for execute-only text.
if (Kind.isExecuteOnly())
UniqueID = 0;
return Ctx.getELFSection(Name, getELFSectionType(Name, Kind), Flags,
EntrySize, Group, IsComdat, UniqueID,
AssociatedSymbol);
}
static MCSection *selectELFSectionForGlobal(
MCContext &Ctx, const GlobalObject *GO, SectionKind Kind, Mangler &Mang,
const TargetMachine &TM, bool EmitUniqueSection, unsigned Flags,
unsigned *NextUniqueID) {
const MCSymbolELF *LinkedToSym = getLinkedToSymbol(GO, TM);
if (LinkedToSym) {
EmitUniqueSection = true;
Flags |= ELF::SHF_LINK_ORDER;
}
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);
// 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,
EmitUniqueSection, Flags, &NextUniqueID);
}
MCSection *TargetLoweringObjectFileELF::getUniqueSectionForFunction(
const Function &F, const TargetMachine &TM) const {
SectionKind Kind = SectionKind::getText();
unsigned Flags = getELFSectionFlags(Kind);
return selectELFSectionForGlobal(getContext(), &F, Kind, getMangler(), TM,
/* EmitUniqueSection = */ true, Flags,
&NextUniqueID);
}
MCSection *TargetLoweringObjectFileELF::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;
return selectELFSectionForGlobal(getContext(), &F, SectionKind::getReadOnly(),
getMangler(), TM, EmitUniqueSection,
ELF::SHF_ALLOC, &NextUniqueID,
/* AssociatedSymbol */ nullptr);
}
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 = cast<MCSectionELF>(LSDASection);
unsigned Flags = LSDA->getFlags();
const MCSymbolELF *LinkedToSym = nullptr;
StringRef Group;
if (const Comdat *C = getELFComdat(&F)) {
Flags |= ELF::SHF_GROUP;
Group = C->getName();
}
// 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 = cast<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, F.hasComdat(), 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 {
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;
}
/// 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 = MCContext::GenericSectionID;
// 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;
if (MBB.getSectionID() == MBBSectionID::ColdSectionID) {
Name += BBSectionsColdTextPrefix;
Name += MBB.getParent()->getName();
} else if (MBB.getSectionID() == MBBSectionID::ExceptionSectionID) {
Name += ".text.eh.";
Name += MBB.getParent()->getName();
} else {
Name += MBB.getParent()->getSection()->getName();
if (TM.getUniqueBasicBlockSectionNames()) {
if (!Name.endswith("."))
Name += ".";
Name += MBB.getSymbol()->getName();
} else {
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::lowerRelativeReference(
const GlobalValue *LHS, const GlobalValue *RHS,
const TargetMachine &TM) const {
// We may only use a PLT-relative relocation to refer to unnamed_addr
// functions.
if (!LHS->hasGlobalUnnamedAddr() || !LHS->getValueType()->isFunctionTy())
return nullptr;
// Basic sanity checks.
if (LHS->getType()->getPointerAddressSpace() != 0 ||
RHS->getType()->getPointerAddressSpace() != 0 || LHS->isThreadLocal() ||
RHS->isThreadLocal())
return nullptr;
return MCBinaryExpr::createSub(
MCSymbolRefExpr::create(TM.getSymbol(LHS), PLTRelativeVariantKind,
getContext()),
MCSymbolRefExpr::create(TM.getSymbol(RHS), getContext()), getContext());
}
const MCExpr *TargetLoweringObjectFileELF::lowerDSOLocalEquivalent(
const DSOLocalEquivalent *Equiv, const TargetMachine &TM) const {
assert(supportDSOLocalEquivalentLowering());
const auto *GV = Equiv->getGlobalValue();
// A PLT entry is not needed for dso_local globals.
if (GV->isDSOLocal() || GV->isImplicitDSOLocal())
return MCSymbolRefExpr::create(TM.getSymbol(GV), getContext());
return MCSymbolRefExpr::create(TM.getSymbol(GV), PLTRelativeVariantKind,
getContext());
}
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()
: TargetLoweringObjectFile() {
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;
}
void TargetLoweringObjectFileMachO::emitModuleMetadata(MCStreamer &Streamer,
Module &M) const {
// Emit the linker options if present.
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);
}
}
unsigned VersionVal = 0;
unsigned ImageInfoFlags = 0;
StringRef SectionVal;
GetObjCImageInfo(M, VersionVal, ImageInfoFlags, SectionVal);
// 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;
std::string ErrorCode =
MCSectionMachO::ParseSectionSpecifier(SectionVal, Segment, Section,
TAA, TAAParsed, StubSize);
if (!ErrorCode.empty())
// If invalid, report the error with report_fatal_error.
report_fatal_error("Invalid section specifier '" + Section + "': " +
ErrorCode + ".");
// 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();
}
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 {
// Parse the section specifier and create it if valid.
StringRef Segment, Section;
unsigned TAA = 0, StubSize = 0;
bool TAAParsed;
checkMachOComdat(GO);
std::string ErrorCode =
MCSectionMachO::ParseSectionSpecifier(GO->getSection(), Segment, Section,
TAA, TAAParsed, StubSize);
if (!ErrorCode.empty()) {
// If invalid, report the error with report_fatal_error.
report_fatal_error("Global variable '" + GO->getName() +
"' has an invalid section specifier '" +
GO->getSection() + "': " + ErrorCode + ".");
}
// 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->getParent()->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->getParent()->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 {
// 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
}
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.getSymB()->getSymbol();
// 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().getPrivateGlobalPrefix();
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, MCSymbolRefExpr::VK_None, Ctx);
const MCExpr *LHS =
MCSymbolRefExpr::create(Stub, MCSymbolRefExpr::VK_None, 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 (!AsmInfo.isSectionAtomizableBySymbols(Section))
return true;
// If it is not dead stripped, it is safe to use private labels.
const MCSectionMachO &SMO = cast<MCSectionMachO>(Section);
if (SMO.hasAttribute(MachO::S_ATTR_NO_DEAD_STRIP))
return true;
return false;
}
void TargetLoweringObjectFileMachO::getNameWithPrefix(
SmallVectorImpl<char> &OutName, const GlobalValue *GV,
const TargetMachine &TM) const {
bool CannotUsePrivateLabel = true;
if (auto *GO = GV->getBaseObject()) {
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.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->getBaseObject();
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::NoDuplicates:
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 {
int Selection = 0;
unsigned Characteristics = getCOFFSectionFlags(Kind, TM);
StringRef Name = GO->getSection();
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, Kind, COMDATSymName,
Selection);
}
static StringRef getCOFFSectionNameForUniqueGlobal(SectionKind Kind) {
if (Kind.isText())
return ".text";
if (Kind.isBSS())
return ".bss";
if (Kind.isThreadLocal())
return ".tls$";
if (Kind.isReadOnly() || Kind.isReadOnlyWithRel())
return ".rdata";
return ".data";
}
MCSection *TargetLoweringObjectFileCOFF::SelectSectionForGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
// If we have -ffunction-sections then we should emit the global value to a
// uniqued section specifically for it.
bool EmitUniquedSection;
if (Kind.isText())
EmitUniquedSection = TM.getFunctionSections();
else
EmitUniquedSection = TM.getDataSections();
if ((EmitUniquedSection && !Kind.isCommon()) || GO->hasComdat()) {
SmallString<256> Name = getCOFFSectionNameForUniqueGlobal(Kind);
unsigned Characteristics = getCOFFSectionFlags(Kind, TM);
Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
int Selection = getSelectionForCOFF(GO);
if (!Selection)
Selection = COFF::IMAGE_COMDAT_SELECT_NODUPLICATES;
const GlobalValue *ComdatGV;
if (GO->hasComdat())
ComdatGV = getComdatGVForCOFF(GO);
else
ComdatGV = GO;
unsigned UniqueID = MCContext::GenericSectionID;
if (EmitUniquedSection)
UniqueID = NextUniqueID++;
if (!ComdatGV->hasPrivateLinkage()) {
MCSymbol *Sym = TM.getSymbol(ComdatGV);
StringRef COMDATSymName = Sym->getName();
if (const auto *F = dyn_cast<Function>(GO))
if (Optional<StringRef> Prefix = F->getSectionPrefix())
raw_svector_ostream(Name) << '$' << *Prefix;
// Append "$symbol" to the section name *before* IR-level mangling is
// applied when targetting mingw. This is what GCC does, and the ld.bfd
// COFF linker will not properly handle comdats otherwise.
if (getTargetTriple().isWindowsGNUEnvironment())
raw_svector_ostream(Name) << '$' << ComdatGV->getName();
return getContext().getCOFFSection(Name, Characteristics, Kind,
COMDATSymName, Selection, UniqueID);
} else {
SmallString<256> TmpData;
getMangler().getNameWithPrefix(TmpData, GO, /*CannotUsePrivateLabel=*/true);
return getContext().getCOFFSection(Name, Characteristics, Kind, 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, Kind, COMDATSymName,
COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE, UniqueID);
}
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,
SectionKind::getReadOnly());
Streamer.SwitchSection(S);
Streamer.emitLabel(C.getOrCreateSymbol(StringRef("OBJC_IMAGE_INFO")));
Streamer.emitInt32(Version);
Streamer.emitInt32(Flags);
Streamer.AddBlankLine();
}
emitCGProfileMetadata(Streamer, M);
}
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, getTargetTriple(), getMangler());
OS.flush();
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, getTargetTriple(), getMangler());
OS.flush();
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$XCU", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getReadOnly());
StaticDtorSection =
Ctx.getCOFFSection(".CRT$XTX", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getReadOnly());
} else {
StaticCtorSection = Ctx.getCOFFSection(
".ctors", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE,
SectionKind::getData());
StaticDtorSection = Ctx.getCOFFSection(
".dtors", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE,
SectionKind::getData());
}
}
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.
SmallString<24> Name;
raw_svector_ostream OS(Name);
OS << ".CRT$X" << (IsCtor ? "C" : "T") <<
(Priority < 200 ? 'A' : 'T') << format("%05u", Priority);
MCSectionCOFF *Sec = Ctx.getCOFFSection(
Name, COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
SectionKind::getReadOnly());
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,
SectionKind::getData()),
KeySym, 0);
}
MCSection *TargetLoweringObjectFileCOFF::getStaticCtorSection(
unsigned Priority, const MCSymbol *KeySym) const {
return getCOFFStaticStructorSection(getContext(), getTargetTriple(), true,
Priority, KeySym,
cast<MCSectionCOFF>(StaticCtorSection));
}
MCSection *TargetLoweringObjectFileCOFF::getStaticDtorSection(
unsigned Priority, const MCSymbol *KeySym) const {
return getCOFFStaticStructorSection(getContext(), getTargetTriple(), false,
Priority, KeySym,
cast<MCSectionCOFF>(StaticDtorSection));
}
const MCExpr *TargetLoweringObjectFileCOFF::lowerRelativeReference(
const GlobalValue *LHS, const GlobalValue *RHS,
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;
return MCSymbolRefExpr::create(TM.getSymbol(LHS),
MCSymbolRefExpr::VK_COFF_IMGREL32,
getContext());
}
static std::string APIntToHexString(const APInt &AI) {
unsigned Width = (AI.getBitWidth() / 8) * 2;
std::string HexString = AI.toString(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::getNullValue(Ty->getPrimitiveSizeInBits()));
} else if (const auto *CFP = dyn_cast<ConstantFP>(C)) {
return APIntToHexString(CFP->getValueAPF().bitcastToAPInt());
} else if (const auto *CI = dyn_cast<ConstantInt>(C)) {
return APIntToHexString(CI->getValue());
} 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 {
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, Kind,
COMDATSymName,
COFF::IMAGE_COMDAT_SELECT_ANY);
}
return TargetLoweringObjectFile::getSectionForConstant(DL, Kind, C,
Alignment);
}
//===----------------------------------------------------------------------===//
// 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;
}
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 == ".llvmcmd" || Name == ".llvmbc")
Kind = SectionKind::getMetadata();
StringRef Group = "";
if (const Comdat *C = getWasmComdat(GO)) {
Group = C->getName();
}
MCSectionWasm* Section =
getContext().getWasmSection(Name, Kind, Group,
MCContext::GenericSectionID);
return Section;
}
static MCSectionWasm *selectWasmSectionForGlobal(
MCContext &Ctx, const GlobalObject *GO, SectionKind Kind, Mangler &Mang,
const TargetMachine &TM, bool EmitUniqueSection, unsigned *NextUniqueID) {
StringRef Group = "";
if (const Comdat *C = getWasmComdat(GO)) {
Group = C->getName();
}
bool UniqueSectionNames = TM.getUniqueSectionNames();
SmallString<128> Name = getSectionPrefixForGlobal(Kind);
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 = MCContext::GenericSectionID;
if (EmitUniqueSection && !UniqueSectionNames) {
UniqueID = *NextUniqueID;
(*NextUniqueID)++;
}
return Ctx.getWasmSection(Name, Kind, 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();
return selectWasmSectionForGlobal(getContext(), GO, Kind, getMangler(), TM,
EmitUniqueSection, &NextUniqueID);
}
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;
}
const MCExpr *TargetLoweringObjectFileWasm::lowerRelativeReference(
const GlobalValue *LHS, const GlobalValue *RHS,
const TargetMachine &TM) const {
// We may only use a PLT-relative relocation to refer to unnamed_addr
// functions.
if (!LHS->hasGlobalUnnamedAddr() || !LHS->getValueType()->isFunctionTy())
return nullptr;
// Basic sanity checks.
if (LHS->getType()->getPointerAddressSpace() != 0 ||
RHS->getType()->getPointerAddressSpace() != 0 || LHS->isThreadLocal() ||
RHS->isThreadLocal())
return nullptr;
return MCBinaryExpr::createSub(
MCSymbolRefExpr::create(TM.getSymbol(LHS), MCSymbolRefExpr::VK_None,
getContext()),
MCSymbolRefExpr::create(TM.getSymbol(RHS), getContext()), getContext());
}
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 {
llvm_unreachable("@llvm.global_dtors should have been lowered already");
return nullptr;
}
//===----------------------------------------------------------------------===//
// 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 Function *Per =
dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
if (isNoOpWithoutInvoke(classifyEHPersonality(Per)))
return false;
return true;
}
MCSymbol *
TargetLoweringObjectFileXCOFF::getEHInfoTableSymbol(const MachineFunction *MF) {
return MF->getMMI().getContext().getOrCreateSymbol(
"__ehinfo." + Twine(MF->getFunctionNumber()));
}
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.
// 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 cast<MCSectionXCOFF>(getSectionForExternalReference(GO, TM))
->getQualNameSymbol();
SectionKind GOKind = getKindForGlobal(GO, TM);
if (GOKind.isText())
return cast<MCSectionXCOFF>(
getSectionForFunctionDescriptor(cast<Function>(GO), TM))
->getQualNameSymbol();
if ((TM.getDataSections() && !GO->hasSection()) || GOKind.isCommon() ||
GOKind.isBSSLocal())
return cast<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();
XCOFF::StorageMappingClass MappingClass;
if (Kind.isText())
MappingClass = XCOFF::XMC_PR;
else if (Kind.isData() || Kind.isReadOnlyWithRel() || Kind.isBSS())
MappingClass = 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);
// Externals go into a csect of type ER.
return getContext().getXCOFFSection(
Name, SectionKind::getMetadata(),
XCOFF::CsectProperties(isa<Function>(GO) ? XCOFF::XMC_DS : XCOFF::XMC_UA,
XCOFF::XTY_ER));
}
MCSection *TargetLoweringObjectFileXCOFF::SelectSectionForGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
// Common symbols go into a csect with matching name which will get mapped
// into the .bss section.
if (Kind.isBSSLocal() || Kind.isCommon()) {
SmallString<128> Name;
getNameWithPrefix(Name, GO, TM);
return getContext().getXCOFFSection(
Name, Kind,
XCOFF::CsectProperties(
Kind.isBSSLocal() ? XCOFF::XMC_BS : XCOFF::XMC_RW, XCOFF::XTY_CM));
}
if (Kind.isMergeableCString()) {
Align Alignment = GO->getParent()->getDataLayout().getPreferredAlign(
cast<GlobalVariable>(GO));
unsigned EntrySize = getEntrySizeForKind(Kind);
std::string SizeSpec = ".rodata.str" + utostr(EntrySize) + ".";
SmallString<128> Name;
Name = SizeSpec + utostr(Alignment.value());
if (TM.getDataSections())
getNameWithPrefix(Name, GO, TM);
return getContext().getXCOFFSection(
Name, Kind, XCOFF::CsectProperties(XCOFF::XMC_RO, XCOFF::XTY_SD),
/* MultiSymbolsAllowed*/ !TM.getDataSections());
}
if (Kind.isText()) {
if (TM.getFunctionSections()) {
return cast<MCSymbolXCOFF>(getFunctionEntryPointSymbol(GO, TM))
->getRepresentedCsect();
}
return TextSection;
}
// TODO: We may put Kind.isReadOnlyWithRel() under option control, because
// user may want to have read-only data with relocations placed into a
// read-only section by the compiler.
// 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 defintions, 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;
}
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 {
//TODO: Enable emiting constant pool to unique sections when we support it.
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;
}
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");
}
const MCExpr *TargetLoweringObjectFileXCOFF::lowerRelativeReference(
const GlobalValue *LHS, const GlobalValue *RHS,
const TargetMachine &TM) const {
report_fatal_error("XCOFF not yet implemented.");
}
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<GlobalAlias>(Func) &&
isa_and_nonnull<Function>(cast<GlobalAlias>(Func)->getBaseObject()))) &&
"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->isDeclaration()) &&
isa<Function>(Func)) {
return getContext()
.getXCOFFSection(
NameStr, SectionKind::getText(),
XCOFF::CsectProperties(XCOFF::XMC_PR, Func->isDeclaration()
? XCOFF::XTY_ER
: XCOFF::XTY_SD))
->getQualNameSymbol();
}
return getContext().getOrCreateSymbol(NameStr);
}
MCSection *TargetLoweringObjectFileXCOFF::getSectionForFunctionDescriptor(
const Function *F, const TargetMachine &TM) const {
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 {
// Use TE storage-mapping class when large code model is enabled so that
// the chance of needing -bbigtoc is decreased.
return getContext().getXCOFFSection(
cast<MCSymbolXCOFF>(Sym)->getSymbolTableName(), SectionKind::getData(),
XCOFF::CsectProperties(
TM.getCodeModel() == CodeModel::Large ? XCOFF::XMC_TE : XCOFF::XMC_TC,
XCOFF::XTY_SD));
}
Reference in New Issue View Git Blame Copy Permalink