llvm/lld/MachO/Writer.h
Jez Ng 6f63216c3d [lld-macho] Extend SyntheticSections to cover all segment load commands
Previously, the special segments `__PAGEZERO` and `__LINKEDIT` were
implemented as special LoadCommands. This diff implements them using
special sections instead which have an `isHidden()` attribute. We do not
emit section headers for hidden sections, but we use their addresses and
file offsets to determine that of their containing segments. In addition
to allowing us to share more segment-related code, this refactor is also
important for the next step of emitting dylibs:

1) dylibs don't have segments like __PAGEZERO, so we need an easy way of
   omitting them w/o messing up segment indices
2) Unlike the kernel, which is happy to run an executable with
   out-of-order segments, dyld requires dylibs to have their segment
   load commands arranged in increasing address order. The refactor
   makes it easier to implement sorting of sections and segments.

Differential Revision: https://reviews.llvm.org/D76839
2020-04-27 12:58:12 -07:00

32 lines
738 B
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//===- Writer.h -------------------------------------------------*- 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
//
//===----------------------------------------------------------------------===//
#ifndef LLD_MACHO_WRITER_H
#define LLD_MACHO_WRITER_H
#include <cstdint>
namespace lld {
namespace macho {
class LoadCommand {
public:
virtual ~LoadCommand() = default;
virtual uint32_t getSize() const = 0;
virtual void writeTo(uint8_t *buf) const = 0;
};
void writeResult();
void createSyntheticSections();
} // namespace macho
} // namespace lld
#endif