428a7c1b38
ICF previously operated only within a given OutputSection. We would merge all CFStrings first, then merge all regular code sections in a second phase. This worked fine since CFStrings would never reference regular `__text` sections. However, I would like to expand ICF to merge functions that reference unwind info. Unwind info references the LSDA section, which can in turn reference the `__text` section, so we cannot perform ICF in phases. In order to have ICF operate on InputSections spanning multiple OutputSections, we need a way to distinguish InputSections that are destined for different OutputSections, so that we don't fold across section boundaries. We achieve this by creating OutputSections early, and setting `InputSection::parent` to point to them. This is what LLD-ELF does. (This change should also make it easier to implement the `section$start$` symbols.) This diff also folds InputSections w/o checking their flags, which I think is the right behavior -- if they are destined for the same OutputSection, they will have the same flags in the output (even if their input flags differ). I.e. the `parent` pointer check subsumes the `flags` check. In practice this has nearly no effect (ICF did not become any more effective on chromium_framework). I've also updated ICF.cpp's block comment to better reflect its current status. Reviewed By: #lld-macho, smeenai Differential Revision: https://reviews.llvm.org/D105641
42 lines
1.0 KiB
C++
42 lines
1.0 KiB
C++
//===- Writer.h -------------------------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLD_MACHO_WRITER_H
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#define LLD_MACHO_WRITER_H
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#include <cstdint>
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namespace lld {
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namespace macho {
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class OutputSection;
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class InputSection;
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class Symbol;
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class LoadCommand {
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public:
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virtual ~LoadCommand() = default;
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virtual uint32_t getSize() const = 0;
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virtual void writeTo(uint8_t *buf) const = 0;
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};
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template <class LP> void writeResult();
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void createSyntheticSections();
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// Add bindings for symbols that need weak or non-lazy bindings.
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void addNonLazyBindingEntries(const Symbol *, const InputSection *,
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uint64_t offset, int64_t addend = 0);
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extern OutputSection *firstTLVDataSection;
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} // namespace macho
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} // namespace lld
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#endif
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