aboutsummaryrefslogtreecommitdiffstats
path: root/lib/ReaderWriter/MachO/TLVPass.cpp
blob: 5f457b863d904a6c7de5caa3eeafa824a782b770 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
//===- lib/ReaderWriter/MachO/TLVPass.cpp -----------------------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This linker pass transforms all TLV references to real references.
///
//===----------------------------------------------------------------------===//

#include "ArchHandler.h"
#include "File.h"
#include "MachOPasses.h"
#include "lld/Core/Simple.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Debug.h"

namespace lld {
namespace mach_o {

//
// TLVP Entry Atom created by the TLV pass.
//
class TLVPEntryAtom : public SimpleDefinedAtom {
public:
  TLVPEntryAtom(const File &file, bool is64, StringRef name)
      : SimpleDefinedAtom(file), _is64(is64), _name(name) {}

  ~TLVPEntryAtom() override = default;

  ContentType contentType() const override {
    return DefinedAtom::typeTLVInitializerPtr;
  }

  Alignment alignment() const override {
    return _is64 ? 8 : 4;
  }

  uint64_t size() const override {
    return _is64 ? 8 : 4;
  }

  ContentPermissions permissions() const override {
    return DefinedAtom::permRW_;
  }

  ArrayRef<uint8_t> rawContent() const override {
    static const uint8_t zeros[] =
      { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
    return llvm::makeArrayRef(zeros, size());
  }

  StringRef slotName() const {
    return _name;
  }

private:
  const bool _is64;
  StringRef _name;
};

class TLVPass : public Pass {
public:
  TLVPass(const MachOLinkingContext &context)
      : _ctx(context), _archHandler(_ctx.archHandler()),
        _file(*_ctx.make_file<MachOFile>("<mach-o TLV pass>")) {
    _file.setOrdinal(_ctx.getNextOrdinalAndIncrement());
  }

private:
  llvm::Error perform(SimpleFile &mergedFile) override {
    bool allowTLV = _ctx.minOS("10.7", "1.0");

    for (const DefinedAtom *atom : mergedFile.defined()) {
      for (const Reference *ref : *atom) {
        if (!_archHandler.isTLVAccess(*ref))
          continue;

        if (!allowTLV)
          return llvm::make_error<GenericError>(
            "targeted OS version does not support use of thread local "
            "variables in " + atom->name() + " for architecture " +
            _ctx.archName());

        const Atom *target = ref->target();
        assert(target != nullptr);

        const DefinedAtom *tlvpEntry = makeTLVPEntry(target);
        const_cast<Reference*>(ref)->setTarget(tlvpEntry);
        _archHandler.updateReferenceToTLV(ref);
      }
    }

    std::vector<const TLVPEntryAtom*> entries;
    entries.reserve(_targetToTLVP.size());
    for (auto &it : _targetToTLVP)
      entries.push_back(it.second);
    std::sort(entries.begin(), entries.end(),
              [](const TLVPEntryAtom *lhs, const TLVPEntryAtom *rhs) {
                return (lhs->slotName().compare(rhs->slotName()) < 0);
              });

    for (const TLVPEntryAtom *slot : entries)
      mergedFile.addAtom(*slot);

    return llvm::Error::success();
  }

  const DefinedAtom *makeTLVPEntry(const Atom *target) {
    auto pos = _targetToTLVP.find(target);

    if (pos != _targetToTLVP.end())
      return pos->second;

    auto *tlvpEntry = new (_file.allocator())
      TLVPEntryAtom(_file, _ctx.is64Bit(), target->name());
    _targetToTLVP[target] = tlvpEntry;
    const ArchHandler::ReferenceInfo &nlInfo =
      _archHandler.stubInfo().nonLazyPointerReferenceToBinder;
    tlvpEntry->addReference(Reference::KindNamespace::mach_o, nlInfo.arch,
                            nlInfo.kind, 0, target, 0);
    return tlvpEntry;
  }

  const MachOLinkingContext &_ctx;
  mach_o::ArchHandler &_archHandler;
  MachOFile           &_file;
  llvm::DenseMap<const Atom*, const TLVPEntryAtom*> _targetToTLVP;
};

void addTLVPass(PassManager &pm, const MachOLinkingContext &ctx) {
  assert(ctx.needsTLVPass());
  pm.add(std::make_unique<TLVPass>(ctx));
}

} // end namesapce mach_o
} // end namesapce lld