Target.cpp

//===- Target.cpp ---------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Machine-specific things, such as applying relocations, creation of
// GOT or PLT entries, etc., are handled in this file.
//
// Refer the ELF spec for the single letter variables, S, A or P, used
// in this file.
//
// Some functions defined in this file has "relaxTls" as part of their names.
// They do peephole optimization for TLS variables by rewriting instructions.
// They are not part of the ABI but optional optimization, so you can skip
// them if you are not interested in how TLS variables are optimized.
// See the following paper for the details.
//
// Ulrich Drepper, ELF Handling For Thread-Local Storage
// http://www.akkadia.org/drepper/tls.pdf
//
//===----------------------------------------------------------------------===//

#include"Target.h"
#include"InputFiles.h"
#include"OutputSections.h"
#include"SymbolTable.h"
#include"Symbols.h"
#include"lld/Common/ErrorHandler.h"
#include"llvm/Object/ELF.h"

usingnamespacellvm;
usingnamespacellvm::object;
usingnamespacellvm::ELF;
usingnamespacelld;
usingnamespacelld::elf;

const TargetInfo *elf::Target;

std::string lld::toString(RelType Type) {
 StringRef S = getELFRelocationTypeName(elf::Config->EMachine, Type);
if (S == "Unknown")
return ("Unknown (" + Twine(Type) + ")").str();
return S;
}

TargetInfo *elf::getTarget() {
switch (Config->EMachine) {
case EM_386:
case EM_IAMCU:
returngetX86TargetInfo();
case EM_AARCH64:
returngetAArch64TargetInfo();
case EM_AMDGPU:
returngetAMDGPUTargetInfo();
case EM_ARM:
returngetARMTargetInfo();
case EM_AVR:
returngetAVRTargetInfo();
case EM_HEXAGON:
returngetHexagonTargetInfo();
case EM_MIPS:
switch (Config->EKind) {
case ELF32LEKind:
return getMipsTargetInfo<ELF32LE>();
case ELF32BEKind:
return getMipsTargetInfo<ELF32BE>();
case ELF64LEKind:
return getMipsTargetInfo<ELF64LE>();
case ELF64BEKind:
return getMipsTargetInfo<ELF64BE>();
default:
llvm_unreachable("unsupported MIPS target");
 }
case EM_MSP430:
returngetMSP430TargetInfo();
case EM_PPC:
returngetPPCTargetInfo();
case EM_PPC64:
returngetPPC64TargetInfo();
case EM_RISCV:
returngetRISCVTargetInfo();
case EM_SPARCV9:
returngetSPARCV9TargetInfo();
case EM_X86_64:
returngetX86_64TargetInfo();
 }
llvm_unreachable("unknown target machine");
}

template <classELFT> static ErrorPlace getErrPlace(constuint8_t *Loc) {
for (InputSectionBase *D : InputSections) {
auto *IS = cast<InputSection>(D);
if (!IS->getParent())
continue;

uint8_t *ISLoc = Out::BufferStart + IS->getParent()->Offset + IS->OutSecOff;
if (ISLoc <= Loc && Loc < ISLoc + IS->getSize())
return {IS, IS->templategetLocation<ELFT>(Loc - ISLoc) + ": "};
 }
return {};
}

ErrorPlace elf::getErrorPlace(constuint8_t *Loc) {
switch (Config->EKind) {
case ELF32LEKind:
return getErrPlace<ELF32LE>(Loc);
case ELF32BEKind:
return getErrPlace<ELF32BE>(Loc);
case ELF64LEKind:
return getErrPlace<ELF64LE>(Loc);
case ELF64BEKind:
return getErrPlace<ELF64BE>(Loc);
default:
llvm_unreachable("unknown ELF type");
 }
}

TargetInfo::~TargetInfo() {}

int64_tTargetInfo::getImplicitAddend(constuint8_t *Buf, RelType Type) const {
return0;
}

boolTargetInfo::usesOnlyLowPageBits(RelType Type) const { returnfalse; }

boolTargetInfo::needsThunk(RelExpr Expr, RelType Type, const InputFile *File,
uint64_t BranchAddr, const Symbol &S) const {
returnfalse;
}

boolTargetInfo::adjustPrologueForCrossSplitStack(uint8_t *Loc, uint8_t *End,
uint8_t StOther) const {
llvm_unreachable("Target doesn't support split stacks.");
}

boolTargetInfo::inBranchRange(RelType Type, uint64_t Src, uint64_t Dst) const {
returntrue;
}

voidTargetInfo::writeIgotPlt(uint8_t *Buf, const Symbol &S) const {
writeGotPlt(Buf, S);
}

RelExpr TargetInfo::adjustRelaxExpr(RelType Type, constuint8_t *Data,
 RelExpr Expr) const {
return Expr;
}

voidTargetInfo::relaxGot(uint8_t *Loc, RelType Type, uint64_t Val) const {
llvm_unreachable("Should not have claimed to be relaxable");
}

voidTargetInfo::relaxTlsGdToLe(uint8_t *Loc, RelType Type,
uint64_t Val) const {
llvm_unreachable("Should not have claimed to be relaxable");
}

voidTargetInfo::relaxTlsGdToIe(uint8_t *Loc, RelType Type,
uint64_t Val) const {
llvm_unreachable("Should not have claimed to be relaxable");
}

voidTargetInfo::relaxTlsIeToLe(uint8_t *Loc, RelType Type,
uint64_t Val) const {
llvm_unreachable("Should not have claimed to be relaxable");
}

voidTargetInfo::relaxTlsLdToLe(uint8_t *Loc, RelType Type,
uint64_t Val) const {
llvm_unreachable("Should not have claimed to be relaxable");
}

uint64_tTargetInfo::getImageBase() const {
// Use -image-base if set. Fall back to the target default if not.
if (Config->ImageBase)
return *Config->ImageBase;
return Config->Pic ? 0 : DefaultImageBase;
}