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 "InputFiles.h"
11 #include "OutputSegment.h"
12 #include "Symbols.h"
13 #include "Target.h"
14 #include "lld/Common/Memory.h"
15 #include "llvm/Support/Endian.h"
16 
17 using namespace llvm;
18 using namespace llvm::MachO;
19 using namespace llvm::support;
20 using namespace lld;
21 using namespace lld::macho;
22 
23 std::vector<InputSection *> macho::inputSections;
24 
25 uint64_t InputSection::getFileOffset() const {
26   return parent->fileOff + outSecFileOff;
27 }
28 
29 uint64_t InputSection::getVA() const { return parent->addr + outSecOff; }
30 
31 void InputSection::writeTo(uint8_t *buf) {
32   if (getFileSize() == 0)
33     return;
34 
35   memcpy(buf, data.data(), data.size());
36 
37   for (Reloc &r : relocs) {
38     uint64_t referentVA = 0;
39     if (auto *referentSym = r.referent.dyn_cast<Symbol *>()) {
40       referentVA =
41           target->resolveSymbolVA(buf + r.offset, *referentSym, r.type);
42 
43       if (isThreadLocalVariables(flags)) {
44         // References from thread-local variable sections are treated
45         // as offsets relative to the start of the referent section,
46         // instead of as absolute addresses.
47         if (auto *defined = dyn_cast<Defined>(referentSym))
48           referentVA -= defined->isec->parent->addr;
49       }
50     } else if (auto *referentIsec = r.referent.dyn_cast<InputSection *>()) {
51       referentVA = referentIsec->getVA();
52     }
53 
54     uint64_t referentVal = referentVA + r.addend;
55     if (r.pcrel)
56       referentVal -= getVA() + r.offset;
57     target->relocateOne(buf + r.offset, r, referentVal);
58   }
59 }
60 
61 bool macho::isCodeSection(InputSection *isec) {
62   uint32_t type = isec->flags & MachO::SECTION_TYPE;
63   if (type != S_REGULAR && type != S_COALESCED)
64     return false;
65 
66   uint32_t attr = isec->flags & MachO::SECTION_ATTRIBUTES_USR;
67   if (attr == S_ATTR_PURE_INSTRUCTIONS)
68     return true;
69 
70   if (isec->segname == segment_names::text)
71     return StringSwitch<bool>(isec->name)
72         .Cases("__textcoal_nt", "__StaticInit", true)
73         .Default(false);
74 
75   return false;
76 }
77 
78 std::string lld::toString(const InputSection *isec) {
79   return (toString(isec->file) + ":(" + isec->name + ")").str();
80 }
81