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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
75 lines
2.2 KiB
C++
75 lines
2.2 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_OUTPUT_SECTION_H
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#define LLD_MACHO_OUTPUT_SECTION_H
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#include "lld/Common/LLVM.h"
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#include "llvm/ADT/DenseMap.h"
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namespace lld {
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namespace macho {
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class InputSection;
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class OutputSegment;
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// Output sections represent the finalized sections present within the final
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// linked executable. They can represent special sections (like the symbol
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// table), or represent coalesced sections from the various inputs given to the
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// linker with the same segment / section name.
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class OutputSection {
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public:
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enum Kind {
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MergedKind,
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SyntheticKind,
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};
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OutputSection(Kind kind, StringRef name) : name(name), sectionKind(kind) {}
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virtual ~OutputSection() = default;
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Kind kind() const { return sectionKind; }
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// These accessors will only be valid after finalizing the section.
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uint64_t getSegmentOffset() const;
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// How much space the section occupies in the address space.
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virtual uint64_t getSize() const = 0;
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// How much space the section occupies in the file. Most sections are copied
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// as-is so their file size is the same as their address space size.
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virtual uint64_t getFileSize() const { return getSize(); }
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// Hidden sections omit header content, but body content may still be present.
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virtual bool isHidden() const { return false; }
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// Unneeded sections are omitted entirely (header and body).
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virtual bool isNeeded() const { return true; }
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// Specifically finalizes addresses and section size, not content.
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virtual void finalize() {
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// TODO investigate refactoring synthetic section finalization logic into
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// overrides of this function.
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}
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virtual void writeTo(uint8_t *buf) const = 0;
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StringRef name;
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OutputSegment *parent = nullptr;
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uint32_t index = 0;
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uint64_t addr = 0;
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uint64_t fileOff = 0;
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uint32_t align = 1;
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uint32_t flags = 0;
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private:
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Kind sectionKind;
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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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