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f6dbc2edee
This avoids the Writer unnecessarily having a member to retain ownership of the function body. Differential Revision: https://reviews.llvm.org/D43933 llvm-svn: 326580
173 lines
5.3 KiB
C++
173 lines
5.3 KiB
C++
//===- InputChunks.h --------------------------------------------*- C++ -*-===//
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//
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// The LLVM Linker
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// An InputChunks represents an indivisible opaque region of a input wasm file.
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// i.e. a single wasm data segment or a single wasm function.
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//
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// They are written directly to the mmap'd output file after which relocations
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// are applied. Because each Chunk is independent they can be written in
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// parallel.
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//
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// Chunks are also unit on which garbage collection (--gc-sections) operates.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLD_WASM_INPUT_CHUNKS_H
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#define LLD_WASM_INPUT_CHUNKS_H
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#include "Config.h"
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#include "InputFiles.h"
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#include "lld/Common/ErrorHandler.h"
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#include "lld/Common/Strings.h"
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#include "llvm/Object/Wasm.h"
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using llvm::object::WasmSegment;
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using llvm::wasm::WasmFunction;
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using llvm::wasm::WasmRelocation;
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using llvm::wasm::WasmSignature;
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using llvm::object::WasmSection;
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namespace llvm {
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class raw_ostream;
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}
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namespace lld {
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namespace wasm {
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class ObjFile;
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class OutputSegment;
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class InputChunk {
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public:
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enum Kind { DataSegment, Function };
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Kind kind() const { return SectionKind; }
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uint32_t getSize() const { return data().size(); }
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void copyRelocations(const WasmSection &Section);
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void writeTo(uint8_t *SectionStart) const;
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ArrayRef<WasmRelocation> getRelocations() const { return Relocations; }
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virtual StringRef getComdat() const = 0;
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virtual StringRef getName() const = 0;
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size_t NumRelocations() const { return Relocations.size(); }
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void writeRelocations(llvm::raw_ostream &OS) const;
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ObjFile *File;
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int32_t OutputOffset = 0;
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// Signals that the section is part of the output. The garbage collector,
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// and COMDAT handling can set a sections' Live bit.
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// If GC is disabled, all sections start out as live by default.
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unsigned Live : 1;
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protected:
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InputChunk(ObjFile *F, Kind K)
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: File(F), Live(!Config->GcSections), SectionKind(K) {}
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virtual ~InputChunk() = default;
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virtual ArrayRef<uint8_t> data() const = 0;
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virtual uint32_t getInputSectionOffset() const = 0;
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std::vector<WasmRelocation> Relocations;
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Kind SectionKind;
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};
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// Represents a WebAssembly data segment which can be included as part of
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// an output data segments. Note that in WebAssembly, unlike ELF and other
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// formats, used the term "data segment" to refer to the continous regions of
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// memory that make on the data section. See:
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// https://webassembly.github.io/spec/syntax/modules.html#syntax-data
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//
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// For example, by default, clang will produce a separate data section for
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// each global variable.
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class InputSegment : public InputChunk {
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public:
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InputSegment(const WasmSegment &Seg, ObjFile *F)
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: InputChunk(F, InputChunk::DataSegment), Segment(Seg) {}
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static bool classof(const InputChunk *C) { return C->kind() == DataSegment; }
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uint32_t getAlignment() const { return Segment.Data.Alignment; }
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StringRef getName() const override { return Segment.Data.Name; }
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StringRef getComdat() const override { return Segment.Data.Comdat; }
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const OutputSegment *OutputSeg = nullptr;
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int32_t OutputSegmentOffset = 0;
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protected:
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ArrayRef<uint8_t> data() const override { return Segment.Data.Content; }
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uint32_t getInputSectionOffset() const override {
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return Segment.SectionOffset;
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}
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const WasmSegment &Segment;
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};
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// Represents a single wasm function within and input file. These are
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// combined to create the final output CODE section.
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class InputFunction : public InputChunk {
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public:
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InputFunction(const WasmSignature &S, const WasmFunction *Func,
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ObjFile *F)
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: InputChunk(F, InputChunk::Function), Signature(S), Function(Func) {}
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static bool classof(const InputChunk *C) {
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return C->kind() == InputChunk::Function;
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}
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StringRef getName() const override { return Function->Name; }
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StringRef getComdat() const override { return Function->Comdat; }
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uint32_t getOutputIndex() const { return OutputIndex.getValue(); }
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bool hasOutputIndex() const { return OutputIndex.hasValue(); }
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void setOutputIndex(uint32_t Index);
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uint32_t getTableIndex() const { return TableIndex.getValue(); }
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bool hasTableIndex() const { return TableIndex.hasValue(); }
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void setTableIndex(uint32_t Index);
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const WasmSignature &Signature;
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protected:
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ArrayRef<uint8_t> data() const override {
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return File->CodeSection->Content.slice(getInputSectionOffset(),
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Function->Size);
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}
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uint32_t getInputSectionOffset() const override {
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return Function->CodeSectionOffset;
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}
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const WasmFunction *Function;
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llvm::Optional<uint32_t> OutputIndex;
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llvm::Optional<uint32_t> TableIndex;
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};
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class SyntheticFunction : public InputFunction {
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public:
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SyntheticFunction(const WasmSignature &S, std::string Body, StringRef Name)
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: InputFunction(S, nullptr, nullptr), Name(Name), Body(std::move(Body)) {}
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StringRef getName() const override { return Name; }
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protected:
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ArrayRef<uint8_t> data() const override { return toArrayRef(Body); }
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StringRef Name;
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std::string Body;
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};
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} // namespace wasm
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std::string toString(const wasm::InputChunk *);
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} // namespace lld
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#endif // LLD_WASM_INPUT_CHUNKS_H
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