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//===- 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 "SyntheticSections.h"
#include "lld/Common/ErrorHandler.h"
#include "llvm/Object/ELF.h"
using namespace llvm;
using namespace llvm::object;
using namespace llvm::ELF;
using namespace lld;
using namespace lld::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 std::string(s);
}
TargetInfo *elf::getTarget() {
switch (config->emachine) {
case EM_386:
case EM_IAMCU:
return getX86TargetInfo();
case EM_AARCH64:
return getAArch64TargetInfo();
case EM_AMDGPU:
return getAMDGPUTargetInfo();
case EM_ARM:
return getARMTargetInfo();
case EM_AVR:
return getAVRTargetInfo();
case EM_HEXAGON:
return getHexagonTargetInfo();
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:
return getMSP430TargetInfo();
case EM_PPC:
return getPPCTargetInfo();
case EM_PPC64:
return getPPC64TargetInfo();
case EM_RISCV:
return getRISCVTargetInfo();
case EM_SPARCV9:
return getSPARCV9TargetInfo();
case EM_X86_64:
return getX86_64TargetInfo();
}
llvm_unreachable("unknown target machine");
}
template <class ELFT> static ErrorPlace getErrPlace(const uint8_t *loc) {
assert(loc != nullptr);
for (InputSectionBase *d : inputSections) {
auto *isec = cast<InputSection>(d);
if (!isec->getParent() || (isec->type & SHT_NOBITS))
continue;
const uint8_t *isecLoc =
Out::bufferStart
? (Out::bufferStart + isec->getParent()->offset + isec->outSecOff)
: isec->data().data();
if (isecLoc == nullptr) {
assert(isa<SyntheticSection>(isec) && "No data but not synthetic?");
continue;
}
if (isecLoc <= loc && loc < isecLoc + isec->getSize())
return {isec, isec->template getLocation<ELFT>(loc - isecLoc) + ": "};
}
return {};
}
ErrorPlace elf::getErrorPlace(const uint8_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_t TargetInfo::getImplicitAddend(const uint8_t *buf, RelType type) const {
return 0;
}
bool TargetInfo::usesOnlyLowPageBits(RelType type) const { return false; }
bool TargetInfo::needsThunk(RelExpr expr, RelType type, const InputFile *file,
uint64_t branchAddr, const Symbol &s,
int64_t a) const {
return false;
}
bool TargetInfo::adjustPrologueForCrossSplitStack(uint8_t *loc, uint8_t *end,
uint8_t stOther) const {
llvm_unreachable("Target doesn't support split stacks.");
}
bool TargetInfo::inBranchRange(RelType type, uint64_t src, uint64_t dst) const {
return true;
}
RelExpr TargetInfo::adjustTlsExpr(RelType type, RelExpr expr) const {
return expr;
}
RelExpr TargetInfo::adjustGotPcExpr(RelType type, int64_t addend,
const uint8_t *data) const {
return R_GOT_PC;
}
void TargetInfo::relaxGot(uint8_t *loc, const Relocation &rel,
uint64_t val) const {
llvm_unreachable("Should not have claimed to be relaxable");
}
void TargetInfo::relaxTlsGdToLe(uint8_t *loc, const Relocation &rel,
uint64_t val) const {
llvm_unreachable("Should not have claimed to be relaxable");
}
void TargetInfo::relaxTlsGdToIe(uint8_t *loc, const Relocation &rel,
uint64_t val) const {
llvm_unreachable("Should not have claimed to be relaxable");
}
void TargetInfo::relaxTlsIeToLe(uint8_t *loc, const Relocation &rel,
uint64_t val) const {
llvm_unreachable("Should not have claimed to be relaxable");
}
void TargetInfo::relaxTlsLdToLe(uint8_t *loc, const Relocation &rel,
uint64_t val) const {
llvm_unreachable("Should not have claimed to be relaxable");
}
uint64_t TargetInfo::getImageBase() const {
// Use -image-base if set. Fall back to the target default if not.
if (config->imageBase)
return *config->imageBase;
return config->isPic ? 0 : defaultImageBase;
}
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