llvm-project/lld/MachO/InputSection.cpp

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//===- InputSection.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
//
//===----------------------------------------------------------------------===//
#include "InputSection.h"
#include "InputFiles.h"
#include "OutputSegment.h"
#include "Symbols.h"
#include "SyntheticSections.h"
#include "Target.h"
#include "Writer.h"
#include "lld/Common/Memory.h"
#include "llvm/Support/Endian.h"
using namespace llvm;
using namespace llvm::MachO;
using namespace llvm::support;
using namespace lld;
using namespace lld::macho;
std::vector<InputSection *> macho::inputSections;
uint64_t InputSection::getFileOffset() const {
return parent->fileOff + outSecFileOff;
}
uint64_t InputSection::getFileSize() const {
return isZeroFill(flags) ? 0 : getSize();
}
uint64_t InputSection::getVA() const { return parent->addr + outSecOff; }
static uint64_t resolveSymbolVA(uint8_t *loc, const lld::macho::Symbol &sym,
uint8_t type) {
const TargetInfo::RelocAttrs &relocAttrs = target->getRelocAttrs(type);
if (relocAttrs.hasAttr(RelocAttrBits::BRANCH)) {
if (sym.isInStubs())
return in.stubs->addr + sym.stubsIndex * target->stubSize;
} else if (relocAttrs.hasAttr(RelocAttrBits::GOT | RelocAttrBits::LOAD)) {
if (sym.isInGot())
return in.got->addr + sym.gotIndex * WordSize;
} else if (relocAttrs.hasAttr(RelocAttrBits::GOT)) {
return in.got->addr + sym.gotIndex * WordSize;
} else if (relocAttrs.hasAttr(RelocAttrBits::TLV | RelocAttrBits::LOAD)) {
if (sym.isInGot())
return in.tlvPointers->addr + sym.gotIndex * WordSize;
assert(isa<Defined>(&sym));
}
return sym.getVA();
}
void InputSection::writeTo(uint8_t *buf) {
if (getFileSize() == 0)
return;
memcpy(buf, data.data(), data.size());
for (size_t i = 0; i < relocs.size(); i++) {
const Reloc &r = relocs[i];
uint8_t *loc = buf + r.offset;
auto *fromSym = target->hasAttr(r.type, RelocAttrBits::SUBTRAHEND)
? relocs[i++].referent.dyn_cast<Symbol *>()
: nullptr;
uint64_t referentVA = 0;
if (fromSym) {
auto *toSym = r.referent.dyn_cast<Symbol *>();
referentVA = toSym->getVA() - fromSym->getVA();
} else if (auto *referentSym = r.referent.dyn_cast<Symbol *>()) {
if (target->hasAttr(r.type, RelocAttrBits::LOAD) &&
!referentSym->isInGot())
target->relaxGotLoad(loc, r.type);
referentVA = resolveSymbolVA(loc, *referentSym, r.type);
if (isThreadLocalVariables(flags)) {
// References from thread-local variable sections are treated as offsets
// relative to the start of the thread-local data memory area, which
// is initialized via copying all the TLV data sections (which are all
// contiguous).
if (isa<Defined>(referentSym))
referentVA -= firstTLVDataSection->addr;
}
} else if (auto *referentIsec = r.referent.dyn_cast<InputSection *>()) {
referentVA = referentIsec->getVA();
}
target->relocateOne(loc, r, referentVA, getVA() + r.offset);
}
}
bool macho::isCodeSection(InputSection *isec) {
uint32_t type = isec->flags & MachO::SECTION_TYPE;
if (type != S_REGULAR && type != S_COALESCED)
return false;
uint32_t attr = isec->flags & MachO::SECTION_ATTRIBUTES_USR;
if (attr == S_ATTR_PURE_INSTRUCTIONS)
return true;
if (isec->segname == segment_names::text)
return StringSwitch<bool>(isec->name)
.Cases("__textcoal_nt", "__StaticInit", true)
.Default(false);
return false;
}
std::string lld::toString(const InputSection *isec) {
return (toString(isec->file) + ":(" + isec->name + ")").str();
}