forked from OSchip/llvm-project
87 lines
2.8 KiB
C++
87 lines
2.8 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/DenseMap.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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class Defined;
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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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bool needsThunks() const;
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uint64_t estimateStubsInRangeVA(size_t callIdx) const;
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void writeTo(uint8_t *buf) const override;
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std::vector<InputSection *> inputs;
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std::vector<InputSection *> thunks;
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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(InputSection *input);
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size_t size = 0;
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uint64_t fileSize = 0;
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};
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// We maintain one ThunkInfo per real function.
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//
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// The "active thunk" is represented by the sym/isec pair that
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// turns-over during finalize(): as the call-site address advances,
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// the active thunk goes out of branch-range, and we create a new
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// thunk to take its place.
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//
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// The remaining members -- bools and counters -- apply to the
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// collection of thunks associated with the real function.
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struct ThunkInfo {
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// These denote the active thunk:
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Defined *sym = nullptr; // private-extern symbol for active thunk
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InputSection *isec = nullptr; // input section for active thunk
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// The following values are cumulative across all thunks on this function
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uint32_t callSiteCount = 0; // how many calls to the real function?
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uint32_t callSitesUsed = 0; // how many call sites processed so-far?
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uint32_t thunkCallCount = 0; // how many call sites went to thunk?
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uint8_t sequence = 0; // how many thunks created so-far?
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};
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extern llvm::DenseMap<Symbol *, ThunkInfo> thunkMap;
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} // namespace macho
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} // namespace lld
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#endif
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