OutputSections.h
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//===- OutputSections.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_WASM_OUTPUT_SECTIONS_H
#define LLD_WASM_OUTPUT_SECTIONS_H
#include "InputChunks.h"
#include "WriterUtils.h"
#include "lld/Common/ErrorHandler.h"
#include "lld/Common/LLVM.h"
#include "llvm/ADT/DenseMap.h"
namespace lld {
namespace wasm {
class OutputSection;
}
std::string toString(const wasm::OutputSection §ion);
namespace wasm {
class OutputSegment;
class OutputSection {
public:
OutputSection(uint32_t type, std::string name = "")
: type(type), name(name) {}
virtual ~OutputSection() = default;
StringRef getSectionName() const;
void setOffset(size_t newOffset) {
log("setOffset: " + toString(*this) + ": " + Twine(newOffset));
offset = newOffset;
}
void createHeader(size_t bodySize);
virtual bool isNeeded() const { return true; }
virtual size_t getSize() const = 0;
virtual void writeTo(uint8_t *buf) = 0;
virtual void finalizeContents() = 0;
virtual uint32_t getNumRelocations() const { return 0; }
virtual void writeRelocations(raw_ostream &os) const {}
std::string header;
uint32_t type;
uint32_t sectionIndex = UINT32_MAX;
std::string name;
OutputSectionSymbol *sectionSym = nullptr;
protected:
size_t offset = 0;
};
class CodeSection : public OutputSection {
public:
explicit CodeSection(ArrayRef<InputFunction *> functions)
: OutputSection(llvm::wasm::WASM_SEC_CODE), functions(functions) {}
size_t getSize() const override { return header.size() + bodySize; }
void writeTo(uint8_t *buf) override;
uint32_t getNumRelocations() const override;
void writeRelocations(raw_ostream &os) const override;
bool isNeeded() const override { return functions.size() > 0; }
void finalizeContents() override;
protected:
ArrayRef<InputFunction *> functions;
std::string codeSectionHeader;
size_t bodySize = 0;
};
class DataSection : public OutputSection {
public:
explicit DataSection(ArrayRef<OutputSegment *> segments)
: OutputSection(llvm::wasm::WASM_SEC_DATA), segments(segments) {}
size_t getSize() const override { return header.size() + bodySize; }
void writeTo(uint8_t *buf) override;
uint32_t getNumRelocations() const override;
void writeRelocations(raw_ostream &os) const override;
bool isNeeded() const override;
void finalizeContents() override;
protected:
ArrayRef<OutputSegment *> segments;
std::string dataSectionHeader;
size_t bodySize = 0;
};
// Represents a custom section in the output file. Wasm custom sections are
// used for storing user-defined metadata. Unlike the core sections types
// they are identified by their string name.
// The linker combines custom sections that have the same name by simply
// concatenating them.
// Note that some custom sections such as "name" and "linking" are handled
// separately and are instead synthesized by the linker.
class CustomSection : public OutputSection {
public:
CustomSection(std::string name, ArrayRef<InputSection *> inputSections)
: OutputSection(llvm::wasm::WASM_SEC_CUSTOM, name),
inputSections(inputSections) {}
size_t getSize() const override {
return header.size() + nameData.size() + payloadSize;
}
void writeTo(uint8_t *buf) override;
uint32_t getNumRelocations() const override;
void writeRelocations(raw_ostream &os) const override;
void finalizeContents() override;
protected:
size_t payloadSize = 0;
ArrayRef<InputSection *> inputSections;
std::string nameData;
};
} // namespace wasm
} // namespace lld
#endif // LLD_WASM_OUTPUT_SECTIONS_H