1 //===- InputSection.cpp ---------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "InputSection.h"
10 #include "OutputSegment.h"
11 #include "Symbols.h"
12 #include "Target.h"
13 #include "lld/Common/Memory.h"
14 #include "llvm/Support/Endian.h"
15 
16 using namespace llvm::MachO;
17 using namespace llvm::support;
18 using namespace lld;
19 using namespace lld::macho;
20 
21 std::vector<InputSection *> macho::inputSections;
22 
23 uint64_t InputSection::getFileOffset() const {
24   return parent->fileOff + outSecFileOff;
25 }
26 
27 uint64_t InputSection::getVA() const { return parent->addr + outSecOff; }
28 
29 void InputSection::writeTo(uint8_t *buf) {
30   if (!data.empty())
31     memcpy(buf, data.data(), data.size());
32 
33   for (Reloc &r : relocs) {
34     uint64_t va = 0;
35     uint64_t addend = r.addend;
36     if (auto *s = r.target.dyn_cast<Symbol *>()) {
37       if (auto *dylibSymbol = dyn_cast<DylibSymbol>(s)) {
38         va = target->getDylibSymbolVA(*dylibSymbol, r.type);
39       } else {
40         va = s->getVA();
41       }
42     } else if (auto *isec = r.target.dyn_cast<InputSection *>()) {
43       va = isec->getVA();
44       // The implicit addend for pcrel section relocations is the pcrel offset
45       // in terms of the addresses in the input file. Here we adjust it so that
46       // it describes the offset from the start of the target section.
47       // TODO: Figure out what to do for non-pcrel section relocations.
48       // TODO: The offset of 4 is probably not right for ARM64.
49       addend -= isec->header->addr - (header->addr + r.offset + 4);
50     }
51 
52     uint64_t val = va + addend;
53     if (1) // TODO: handle non-pcrel relocations
54       val -= getVA() + r.offset;
55     target->relocateOne(buf + r.offset, r.type, val);
56   }
57 }
58