llvm-capstone/lld/lib/ReaderWriter/MachO/LayoutPass.h
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

119 lines
4.2 KiB
C++

//===------ lib/ReaderWriter/MachO/LayoutPass.h - Handles Layout of atoms -===//
//
// 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
//
//===----------------------------------------------------------------------===//
#ifndef LLD_READER_WRITER_MACHO_LAYOUT_PASS_H
#define LLD_READER_WRITER_MACHO_LAYOUT_PASS_H
#include "lld/Core/File.h"
#include "lld/Core/Pass.h"
#include "lld/Core/Reader.h"
#include "lld/Core/Simple.h"
#include "llvm/ADT/DenseMap.h"
#include <map>
#include <string>
#include <vector>
namespace lld {
class DefinedAtom;
class SimpleFile;
namespace mach_o {
/// This linker pass does the layout of the atoms. The pass is done after the
/// order their .o files were found on the command line, then by order of the
/// atoms (address) in the .o file. But some atoms have a preferred location
/// in their section (such as pinned to the start or end of the section), so
/// the sort must take that into account too.
class LayoutPass : public Pass {
public:
struct SortKey {
SortKey(OwningAtomPtr<DefinedAtom> &&atom,
const DefinedAtom *root, uint64_t override)
: _atom(std::move(atom)), _root(root), _override(override) {}
OwningAtomPtr<DefinedAtom> _atom;
const DefinedAtom *_root;
uint64_t _override;
// Note, these are only here to appease MSVC bots which didn't like
// the same methods being implemented/deleted in OwningAtomPtr.
SortKey(SortKey &&key) : _atom(std::move(key._atom)), _root(key._root),
_override(key._override) {
key._root = nullptr;
}
SortKey &operator=(SortKey &&key) {
_atom = std::move(key._atom);
_root = key._root;
key._root = nullptr;
_override = key._override;
return *this;
}
private:
SortKey(const SortKey &) = delete;
void operator=(const SortKey&) = delete;
};
typedef std::function<bool (const DefinedAtom *left, const DefinedAtom *right,
bool &leftBeforeRight)> SortOverride;
LayoutPass(const Registry &registry, SortOverride sorter);
/// Sorts atoms in mergedFile by content type then by command line order.
llvm::Error perform(SimpleFile &mergedFile) override;
~LayoutPass() override = default;
private:
// Build the followOn atoms chain as specified by the kindLayoutAfter
// reference type
void buildFollowOnTable(const File::AtomRange<DefinedAtom> &range);
// Build a map of Atoms to ordinals for sorting the atoms
void buildOrdinalOverrideMap(const File::AtomRange<DefinedAtom> &range);
const Registry &_registry;
SortOverride _customSorter;
typedef llvm::DenseMap<const DefinedAtom *, const DefinedAtom *> AtomToAtomT;
typedef llvm::DenseMap<const DefinedAtom *, uint64_t> AtomToOrdinalT;
// A map to be used to sort atoms. It represents the order of atoms in the
// result; if Atom X is mapped to atom Y in this map, X will be located
// immediately before Y in the output file. Y might be mapped to another
// atom, constructing a follow-on chain. An atom cannot be mapped to more
// than one atom unless all but one atom are of size zero.
AtomToAtomT _followOnNexts;
// A map to be used to sort atoms. It's a map from an atom to its root of
// follow-on chain. A root atom is mapped to itself. If an atom is not in
// _followOnNexts, the atom is not in this map, and vice versa.
AtomToAtomT _followOnRoots;
AtomToOrdinalT _ordinalOverrideMap;
// Helper methods for buildFollowOnTable().
const DefinedAtom *findAtomFollowedBy(const DefinedAtom *targetAtom);
bool checkAllPrevAtomsZeroSize(const DefinedAtom *targetAtom);
void setChainRoot(const DefinedAtom *targetAtom, const DefinedAtom *root);
std::vector<SortKey> decorate(File::AtomRange<DefinedAtom> &atomRange) const;
void undecorate(File::AtomRange<DefinedAtom> &atomRange,
std::vector<SortKey> &keys) const;
// Check if the follow-on graph is a correct structure. For debugging only.
void checkFollowonChain(const File::AtomRange<DefinedAtom> &range);
};
} // namespace mach_o
} // namespace lld
#endif // LLD_READER_WRITER_MACHO_LAYOUT_PASS_H