llvm/lld/wasm/InputChunks.h

//===- InputChunks.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
//
//===----------------------------------------------------------------------===//
//
// An InputChunks represents an indivisible opaque region of a input wasm file.
// i.e. a single wasm data segment or a single wasm function.
//
// They are written directly to the mmap'd output file after which relocations
// are applied.  Because each Chunk is independent they can be written in
// parallel.
//
// Chunks are also unit on which garbage collection (--gc-sections) operates.
//
//===----------------------------------------------------------------------===//

#ifndef LLD_WASM_INPUT_CHUNKS_H
#define LLD_WASM_INPUT_CHUNKS_H

#include "Config.h"
#include "InputFiles.h"
#include "lld/Common/ErrorHandler.h"
#include "lld/Common/LLVM.h"
#include "llvm/ADT/CachedHashString.h"
#include "llvm/MC/StringTableBuilder.h"
#include "llvm/Object/Wasm.h"
#include <optional>

namespace lld {
namespace wasm {

class ObjFile;
class OutputSegment;
class OutputSection;

class InputChunk { … };

// Represents a WebAssembly data segment which can be included as part of
// an output data segments.  Note that in WebAssembly, unlike ELF and other
// formats, used the term "data segment" to refer to the continuous regions of
// memory that make on the data section. See:
// https://webassembly.github.io/spec/syntax/modules.html#syntax-data
//
// For example, by default, clang will produce a separate data section for
// each global variable.
class InputSegment : public InputChunk { … };

class SyntheticMergedChunk;

// Merge segment handling copied from lld/ELF/InputSection.h.  Keep in sync
// where possible.

// SectionPiece represents a piece of splittable segment contents.
// We allocate a lot of these and binary search on them. This means that they
// have to be as compact as possible, which is why we don't store the size (can
// be found by looking at the next one).
struct SectionPiece { … };

static_assert …;

// This corresponds segments marked as WASM_SEG_FLAG_STRINGS.
class MergeInputChunk : public InputChunk { … };

// SyntheticMergedChunk is a class that allows us to put mergeable
// sections with different attributes in a single output sections. To do that we
// put them into SyntheticMergedChunk synthetic input sections which are
// attached to regular output sections.
class SyntheticMergedChunk : public InputChunk { … };

// Represents a single wasm function within and input file.  These are
// combined to create the final output CODE section.
class InputFunction : public InputChunk { … };

class SyntheticFunction : public InputFunction { … };

// Represents a single Wasm Section within an input file.
class InputSection : public InputChunk { … };

} // namespace wasm

std::string toString(const wasm::InputChunk *);
StringRef relocTypeToString(uint8_t relocType);

} // namespace lld

#endif // LLD_WASM_INPUT_CHUNKS_H