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3646ee503d
Summary: There were a few issues with the previous setup: 1. The section sorting comparator used a declarative map of section names to determine the correct order, but it turns out we need to match on more than just names -- in particular, an upcoming diff will sort based on whether the S_ZERO_FILL flag is set. This diff changes the sorter to a more imperative but flexible form. 2. We were sorting OutputSections stored in a MapVector, which left the MapVector in an inconsistent state -- the wrong keys map to the wrong values! In practice, we weren't doing key lookups (only container iteration) after the sort, so this was fine, but it was still a dubious state of affairs. This diff copies the OutputSections to a vector before sorting them. 3. We were adding unneeded OutputSections to OutputSegments and then filtering them out later, which meant that we had to remember whether an OutputSegment was in a pre- or post-filtered state. This diff only adds the sections to the segments if they are needed. In addition to those major changes, two minor ones worth noting: 1. I renamed all OutputSection variable names to `osec`, to parallel `isec`. Previously we were using some inconsistent combination of `osec`, `os`, and `section`. 2. I added a check (and a test) for InputSections with names that clashed with those of our synthetic OutputSections. Reviewers: #lld-macho Subscribers: llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D81887
57 lines
1.7 KiB
C++
57 lines
1.7 KiB
C++
//===- OutputSection.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_MERGED_OUTPUT_SECTION_H
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#define LLD_MACHO_MERGED_OUTPUT_SECTION_H
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#include "InputSection.h"
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#include "OutputSection.h"
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#include "lld/Common/LLVM.h"
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#include "llvm/ADT/MapVector.h"
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namespace lld {
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namespace macho {
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// Linking multiple files will inevitably mean resolving sections in different
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// files that are labeled with the same segment and section name. This class
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// contains all such sections and writes the data from each section sequentially
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// in the final binary.
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class MergedOutputSection : public OutputSection {
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public:
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MergedOutputSection(StringRef name) : OutputSection(MergedKind, name) {}
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const InputSection *firstSection() const { return inputs.front(); }
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const InputSection *lastSection() const { return inputs.back(); }
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// These accessors will only be valid after finalizing the section
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uint64_t getSize() const override { return size; }
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uint64_t getFileSize() const override { return fileSize; }
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void mergeInput(InputSection *input);
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void finalize() override;
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void writeTo(uint8_t *buf) const override;
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std::vector<InputSection *> inputs;
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static bool classof(const OutputSection *sec) {
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return sec->kind() == MergedKind;
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}
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private:
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void mergeFlags(uint32_t inputFlags);
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size_t size = 0;
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uint64_t fileSize = 0;
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};
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} // namespace macho
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} // namespace lld
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#endif
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