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 void writeRelocations(raw_ostream &os) const {}
45
46 std::string header;
47 uint32_t type;
48 uint32_t sectionIndex = UINT32_MAX;
49 std::string name;
50 OutputSectionSymbol *sectionSym = nullptr;
51
52protected:
53 size_t offset = 0;
54};
55
56class CodeSection : public OutputSection {
57public:
58 explicit CodeSection(ArrayRef<InputFunction *> functions)
59 : OutputSection(llvm::wasm::WASM_SEC_CODE), functions(functions) {}
60
61 static bool classof(const OutputSection *sec) {
62 return sec->type == llvm::wasm::WASM_SEC_CODE;
63 }
64
65 size_t getSize() const override { return header.size() + bodySize; }
66 void writeTo(uint8_t *buf) override;
67 uint32_t getNumRelocations() const override;
68 void writeRelocations(raw_ostream &os) const override;
69 bool isNeeded() const override { return functions.size() > 0; }
70 void finalizeContents() override;
71
72 ArrayRef<InputFunction *> functions;
73
74protected:
75 std::string codeSectionHeader;
76 size_t bodySize = 0;
77};
78
79class DataSection : public OutputSection {
80public:
81 explicit DataSection(ArrayRef<OutputSegment *> segments)
82 : OutputSection(llvm::wasm::WASM_SEC_DATA), segments(segments) {}
83
84 static bool classof(const OutputSection *sec) {
85 return sec->type == llvm::wasm::WASM_SEC_DATA;
86 }
87
88 size_t getSize() const override { return header.size() + bodySize; }
89 void writeTo(uint8_t *buf) override;
90 uint32_t getNumRelocations() const override;
91 void writeRelocations(raw_ostream &os) const override;
92 bool isNeeded() const override;
93 void finalizeContents() override;
94
95 ArrayRef<OutputSegment *> segments;
96
97protected:
98 std::string dataSectionHeader;
99 size_t bodySize = 0;
100};
101
102// Represents a custom section in the output file. Wasm custom sections are
103// used for storing user-defined metadata. Unlike the core sections types
104// they are identified by their string name.
105// The linker combines custom sections that have the same name by simply
106// concatenating them.
107// Note that some custom sections such as "name" and "linking" are handled
108// separately and are instead synthesized by the linker.
109class CustomSection : public OutputSection {
110public:
111 CustomSection(std::string name, ArrayRef<InputChunk *> inputSections)
112 : OutputSection(llvm::wasm::WASM_SEC_CUSTOM, name),
113 inputSections(inputSections) {}
114
115 static bool classof(const OutputSection *sec) {
116 return sec->type == llvm::wasm::WASM_SEC_CUSTOM;
117 }
118
119 size_t getSize() const override {
120 return header.size() + nameData.size() + payloadSize;
121 }
122 void writeTo(uint8_t *buf) override;
123 uint32_t getNumRelocations() const override;
124 void writeRelocations(raw_ostream &os) const override;
125 void finalizeContents() override;
126
127protected:
128 void finalizeInputSections();
129 size_t payloadSize = 0;
130 std::vector<InputChunk *> inputSections;
131 std::string nameData;
132};
133
134} // namespace wasm
135} // namespace lld
136
137#endif // LLD_WASM_OUTPUT_SECTIONS_H
138

source code of lld/wasm/OutputSections.h