1//===- OutputSections.h -----------------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLD_WASM_OUTPUT_SECTIONS_H
10#define LLD_WASM_OUTPUT_SECTIONS_H
11
12#include "InputChunks.h"
13#include "WriterUtils.h"
14#include "lld/Common/ErrorHandler.h"
15#include "lld/Common/LLVM.h"
16#include "llvm/ADT/DenseMap.h"
17
18namespace lld {
19
20namespace wasm {
21class OutputSection;
22}
23std::string toString(const wasm::OutputSection &section);
24
25namespace wasm {
26
27class OutputSegment;
28
29class OutputSection {
30public:
31 OutputSection(uint32_t type, std::string name = "")
32 : type(type), name(name) {}
33 virtual ~OutputSection() = default;
34
35 StringRef getSectionName() const;
36 void setOffset(size_t newOffset) { offset = newOffset; }
37 void createHeader(size_t bodySize);
38 virtual bool isNeeded() const { return true; }
39 virtual size_t getSize() const = 0;
40 virtual size_t getOffset() { return offset; }
41 virtual void writeTo(uint8_t *buf) = 0;
42 virtual void finalizeContents() = 0;
43 virtual uint32_t getNumRelocations() const { return 0; }
44 virtual uint32_t getNumLiveRelocations() const { return getNumRelocations(); }
45 virtual void writeRelocations(raw_ostream &os) const {}
46
47 std::string header;
48 uint32_t type;
49 uint32_t sectionIndex = UINT32_MAX;
50 std::string name;
51 OutputSectionSymbol *sectionSym = nullptr;
52
53protected:
54 size_t offset = 0;
55};
56
57class CodeSection : public OutputSection {
58public:
59 explicit CodeSection(ArrayRef<InputFunction *> functions)
60 : OutputSection(llvm::wasm::WASM_SEC_CODE), functions(functions) {}
61
62 static bool classof(const OutputSection *sec) {
63 return sec->type == llvm::wasm::WASM_SEC_CODE;
64 }
65
66 size_t getSize() const override { return header.size() + bodySize; }
67 void writeTo(uint8_t *buf) override;
68 uint32_t getNumRelocations() const override;
69 void writeRelocations(raw_ostream &os) const override;
70 bool isNeeded() const override { return functions.size() > 0; }
71 void finalizeContents() override;
72
73 ArrayRef<InputFunction *> functions;
74
75protected:
76 std::string codeSectionHeader;
77 size_t bodySize = 0;
78};
79
80class DataSection : public OutputSection {
81public:
82 explicit DataSection(ArrayRef<OutputSegment *> segments)
83 : OutputSection(llvm::wasm::WASM_SEC_DATA), segments(segments) {}
84
85 static bool classof(const OutputSection *sec) {
86 return sec->type == llvm::wasm::WASM_SEC_DATA;
87 }
88
89 size_t getSize() const override { return header.size() + bodySize; }
90 void writeTo(uint8_t *buf) override;
91 uint32_t getNumRelocations() const override;
92 void writeRelocations(raw_ostream &os) const override;
93 bool isNeeded() const override;
94 void finalizeContents() override;
95
96 ArrayRef<OutputSegment *> segments;
97
98protected:
99 std::string dataSectionHeader;
100 size_t bodySize = 0;
101};
102
103// Represents a custom section in the output file. Wasm custom sections are
104// used for storing user-defined metadata. Unlike the core sections types
105// they are identified by their string name.
106// The linker combines custom sections that have the same name by simply
107// concatenating them.
108// Note that some custom sections such as "name" and "linking" are handled
109// separately and are instead synthesized by the linker.
110class CustomSection : public OutputSection {
111public:
112 CustomSection(std::string name, ArrayRef<InputChunk *> inputSections)
113 : OutputSection(llvm::wasm::WASM_SEC_CUSTOM, name),
114 inputSections(inputSections) {}
115
116 static bool classof(const OutputSection *sec) {
117 return sec->type == llvm::wasm::WASM_SEC_CUSTOM;
118 }
119
120 size_t getSize() const override {
121 return header.size() + nameData.size() + payloadSize;
122 }
123 void writeTo(uint8_t *buf) override;
124 uint32_t getNumRelocations() const override;
125 void writeRelocations(raw_ostream &os) const override;
126 void finalizeContents() override;
127
128protected:
129 void finalizeInputSections();
130 size_t payloadSize = 0;
131 std::vector<InputChunk *> inputSections;
132 std::string nameData;
133};
134
135} // namespace wasm
136} // namespace lld
137
138#endif // LLD_WASM_OUTPUT_SECTIONS_H
139