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1 //===- lib/MC/WasmObjectWriter.cpp - Wasm File Writer ---------------------===//
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2 //
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3 // The LLVM Compiler Infrastructure
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4 //
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5 // This file is distributed under the University of Illinois Open Source
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6 // License. See LICENSE.TXT for details.
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7 //
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8 //===----------------------------------------------------------------------===//
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9 //
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10 // This file implements Wasm object file writer information.
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11 //
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12 //===----------------------------------------------------------------------===//
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13
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14 #include "llvm/ADT/STLExtras.h"
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15 #include "llvm/ADT/SmallPtrSet.h"
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16 #include "llvm/BinaryFormat/Wasm.h"
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17 #include "llvm/MC/MCAsmBackend.h"
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18 #include "llvm/MC/MCAsmInfo.h"
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19 #include "llvm/MC/MCAsmLayout.h"
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20 #include "llvm/MC/MCAssembler.h"
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21 #include "llvm/MC/MCContext.h"
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22 #include "llvm/MC/MCExpr.h"
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23 #include "llvm/MC/MCFixupKindInfo.h"
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24 #include "llvm/MC/MCObjectFileInfo.h"
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25 #include "llvm/MC/MCObjectWriter.h"
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26 #include "llvm/MC/MCSectionWasm.h"
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27 #include "llvm/MC/MCSymbolWasm.h"
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28 #include "llvm/MC/MCValue.h"
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29 #include "llvm/MC/MCWasmObjectWriter.h"
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30 #include "llvm/Support/Casting.h"
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31 #include "llvm/Support/Debug.h"
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32 #include "llvm/Support/ErrorHandling.h"
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33 #include "llvm/Support/LEB128.h"
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34 #include "llvm/Support/StringSaver.h"
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35 #include <vector>
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36
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37 using namespace llvm;
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38
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39 #define DEBUG_TYPE "mc"
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40
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41 namespace {
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42
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43 // For patching purposes, we need to remember where each section starts, both
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44 // for patching up the section size field, and for patching up references to
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45 // locations within the section.
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46 struct SectionBookkeeping {
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47 // Where the size of the section is written.
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48 uint64_t SizeOffset;
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49 // Where the contents of the section starts (after the header).
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50 uint64_t ContentsOffset;
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51 };
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52
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53 // The signature of a wasm function, in a struct capable of being used as a
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54 // DenseMap key.
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55 struct WasmFunctionType {
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56 // Support empty and tombstone instances, needed by DenseMap.
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57 enum { Plain, Empty, Tombstone } State;
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58
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59 // The return types of the function.
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60 SmallVector<wasm::ValType, 1> Returns;
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61
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62 // The parameter types of the function.
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63 SmallVector<wasm::ValType, 4> Params;
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64
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65 WasmFunctionType() : State(Plain) {}
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66
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67 bool operator==(const WasmFunctionType &Other) const {
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68 return State == Other.State && Returns == Other.Returns &&
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69 Params == Other.Params;
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70 }
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71 };
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72
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73 // Traits for using WasmFunctionType in a DenseMap.
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74 struct WasmFunctionTypeDenseMapInfo {
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75 static WasmFunctionType getEmptyKey() {
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76 WasmFunctionType FuncTy;
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77 FuncTy.State = WasmFunctionType::Empty;
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78 return FuncTy;
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79 }
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80 static WasmFunctionType getTombstoneKey() {
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81 WasmFunctionType FuncTy;
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82 FuncTy.State = WasmFunctionType::Tombstone;
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83 return FuncTy;
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84 }
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85 static unsigned getHashValue(const WasmFunctionType &FuncTy) {
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86 uintptr_t Value = FuncTy.State;
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87 for (wasm::ValType Ret : FuncTy.Returns)
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88 Value += DenseMapInfo<int32_t>::getHashValue(int32_t(Ret));
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89 for (wasm::ValType Param : FuncTy.Params)
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90 Value += DenseMapInfo<int32_t>::getHashValue(int32_t(Param));
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91 return Value;
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92 }
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93 static bool isEqual(const WasmFunctionType &LHS,
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94 const WasmFunctionType &RHS) {
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95 return LHS == RHS;
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96 }
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97 };
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98
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99 // A wasm data segment. A wasm binary contains only a single data section
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100 // but that can contain many segments, each with their own virtual location
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101 // in memory. Each MCSection data created by llvm is modeled as its own
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102 // wasm data segment.
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103 struct WasmDataSegment {
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104 MCSectionWasm *Section;
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105 StringRef Name;
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106 uint32_t Offset;
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107 uint32_t Alignment;
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108 uint32_t Flags;
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109 SmallVector<char, 4> Data;
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110 };
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111
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112 // A wasm import to be written into the import section.
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113 struct WasmImport {
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114 StringRef ModuleName;
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115 StringRef FieldName;
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116 unsigned Kind;
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117 int32_t Type;
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118 };
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119
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120 // A wasm function to be written into the function section.
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121 struct WasmFunction {
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122 int32_t Type;
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123 const MCSymbolWasm *Sym;
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124 };
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125
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126 // A wasm export to be written into the export section.
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127 struct WasmExport {
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128 StringRef FieldName;
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129 unsigned Kind;
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130 uint32_t Index;
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131 };
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132
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133 // A wasm global to be written into the global section.
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134 struct WasmGlobal {
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135 wasm::ValType Type;
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136 bool IsMutable;
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137 bool HasImport;
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138 uint64_t InitialValue;
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139 uint32_t ImportIndex;
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140 };
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141
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142 // Information about a single relocation.
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143 struct WasmRelocationEntry {
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144 uint64_t Offset; // Where is the relocation.
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145 const MCSymbolWasm *Symbol; // The symbol to relocate with.
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146 int64_t Addend; // A value to add to the symbol.
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147 unsigned Type; // The type of the relocation.
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148 const MCSectionWasm *FixupSection;// The section the relocation is targeting.
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149
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150 WasmRelocationEntry(uint64_t Offset, const MCSymbolWasm *Symbol,
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151 int64_t Addend, unsigned Type,
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152 const MCSectionWasm *FixupSection)
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153 : Offset(Offset), Symbol(Symbol), Addend(Addend), Type(Type),
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154 FixupSection(FixupSection) {}
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155
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156 bool hasAddend() const {
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157 switch (Type) {
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158 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_LEB:
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159 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
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160 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32:
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161 return true;
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162 default:
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163 return false;
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164 }
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165 }
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166
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167 void print(raw_ostream &Out) const {
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168 Out << "Off=" << Offset << ", Sym=" << *Symbol << ", Addend=" << Addend
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169 << ", Type=" << Type
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170 << ", FixupSection=" << FixupSection->getSectionName();
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171 }
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172
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173 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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174 LLVM_DUMP_METHOD void dump() const { print(dbgs()); }
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175 #endif
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176 };
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177
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178 #if !defined(NDEBUG)
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179 raw_ostream &operator<<(raw_ostream &OS, const WasmRelocationEntry &Rel) {
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180 Rel.print(OS);
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181 return OS;
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182 }
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183 #endif
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184
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185 class WasmObjectWriter : public MCObjectWriter {
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186 /// Helper struct for containing some precomputed information on symbols.
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187 struct WasmSymbolData {
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188 const MCSymbolWasm *Symbol;
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189 StringRef Name;
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190
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191 // Support lexicographic sorting.
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192 bool operator<(const WasmSymbolData &RHS) const { return Name < RHS.Name; }
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193 };
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194
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195 /// The target specific Wasm writer instance.
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196 std::unique_ptr<MCWasmObjectTargetWriter> TargetObjectWriter;
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197
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198 // Relocations for fixing up references in the code section.
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199 std::vector<WasmRelocationEntry> CodeRelocations;
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200
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201 // Relocations for fixing up references in the data section.
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202 std::vector<WasmRelocationEntry> DataRelocations;
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203
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204 // Index values to use for fixing up call_indirect type indices.
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205 // Maps function symbols to the index of the type of the function
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206 DenseMap<const MCSymbolWasm *, uint32_t> TypeIndices;
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207 // Maps function symbols to the table element index space. Used
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208 // for TABLE_INDEX relocation types (i.e. address taken functions).
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209 DenseMap<const MCSymbolWasm *, uint32_t> IndirectSymbolIndices;
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210 // Maps function/global symbols to the function/global index space.
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211 DenseMap<const MCSymbolWasm *, uint32_t> SymbolIndices;
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212
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213 DenseMap<WasmFunctionType, int32_t, WasmFunctionTypeDenseMapInfo>
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214 FunctionTypeIndices;
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215 SmallVector<WasmFunctionType, 4> FunctionTypes;
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216 SmallVector<WasmGlobal, 4> Globals;
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217 unsigned NumGlobalImports = 0;
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218
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219 // TargetObjectWriter wrappers.
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220 bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
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221 unsigned getRelocType(const MCValue &Target, const MCFixup &Fixup) const {
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222 return TargetObjectWriter->getRelocType(Target, Fixup);
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223 }
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224
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225 void startSection(SectionBookkeeping &Section, unsigned SectionId,
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226 const char *Name = nullptr);
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227 void endSection(SectionBookkeeping &Section);
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228
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229 public:
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230 WasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW,
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231 raw_pwrite_stream &OS)
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232 : MCObjectWriter(OS, /*IsLittleEndian=*/true),
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233 TargetObjectWriter(std::move(MOTW)) {}
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234
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235 private:
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236 ~WasmObjectWriter() override;
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237
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238 void reset() override {
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239 CodeRelocations.clear();
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240 DataRelocations.clear();
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241 TypeIndices.clear();
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242 SymbolIndices.clear();
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243 IndirectSymbolIndices.clear();
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244 FunctionTypeIndices.clear();
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245 FunctionTypes.clear();
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246 Globals.clear();
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247 MCObjectWriter::reset();
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248 NumGlobalImports = 0;
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249 }
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250
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251 void writeHeader(const MCAssembler &Asm);
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252
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253 void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
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254 const MCFragment *Fragment, const MCFixup &Fixup,
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255 MCValue Target, uint64_t &FixedValue) override;
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256
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257 void executePostLayoutBinding(MCAssembler &Asm,
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258 const MCAsmLayout &Layout) override;
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259
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260 void writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
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261
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262 void writeString(const StringRef Str) {
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263 encodeULEB128(Str.size(), getStream());
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264 writeBytes(Str);
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265 }
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266
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267 void writeValueType(wasm::ValType Ty) {
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268 encodeSLEB128(int32_t(Ty), getStream());
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269 }
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270
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271 void writeTypeSection(ArrayRef<WasmFunctionType> FunctionTypes);
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272 void writeImportSection(ArrayRef<WasmImport> Imports);
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273 void writeFunctionSection(ArrayRef<WasmFunction> Functions);
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274 void writeTableSection(uint32_t NumElements);
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275 void writeMemorySection(uint32_t DataSize);
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276 void writeGlobalSection();
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277 void writeExportSection(ArrayRef<WasmExport> Exports);
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278 void writeElemSection(ArrayRef<uint32_t> TableElems);
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279 void writeCodeSection(const MCAssembler &Asm, const MCAsmLayout &Layout,
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280 ArrayRef<WasmFunction> Functions);
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281 void writeDataSection(ArrayRef<WasmDataSegment> Segments);
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282 void writeNameSection(ArrayRef<WasmFunction> Functions,
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283 ArrayRef<WasmImport> Imports,
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284 uint32_t NumFuncImports);
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285 void writeCodeRelocSection();
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286 void writeDataRelocSection();
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287 void writeLinkingMetaDataSection(
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288 ArrayRef<WasmDataSegment> Segments, uint32_t DataSize,
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289 SmallVector<std::pair<StringRef, uint32_t>, 4> SymbolFlags,
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290 bool HasStackPointer, uint32_t StackPointerGlobal);
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291
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292 uint32_t getProvisionalValue(const WasmRelocationEntry &RelEntry);
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293 void applyRelocations(ArrayRef<WasmRelocationEntry> Relocations,
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294 uint64_t ContentsOffset);
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295
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296 void writeRelocations(ArrayRef<WasmRelocationEntry> Relocations);
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297 uint32_t getRelocationIndexValue(const WasmRelocationEntry &RelEntry);
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298 uint32_t getFunctionType(const MCSymbolWasm& Symbol);
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299 uint32_t registerFunctionType(const MCSymbolWasm& Symbol);
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300 };
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301
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302 } // end anonymous namespace
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303
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304 WasmObjectWriter::~WasmObjectWriter() {}
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305
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306 // Write out a section header and a patchable section size field.
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307 void WasmObjectWriter::startSection(SectionBookkeeping &Section,
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308 unsigned SectionId,
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309 const char *Name) {
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310 assert((Name != nullptr) == (SectionId == wasm::WASM_SEC_CUSTOM) &&
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311 "Only custom sections can have names");
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312
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313 DEBUG(dbgs() << "startSection " << SectionId << ": " << Name << "\n");
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314 encodeULEB128(SectionId, getStream());
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315
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316 Section.SizeOffset = getStream().tell();
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317
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318 // The section size. We don't know the size yet, so reserve enough space
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319 // for any 32-bit value; we'll patch it later.
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320 encodeULEB128(UINT32_MAX, getStream());
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321
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322 // The position where the section starts, for measuring its size.
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323 Section.ContentsOffset = getStream().tell();
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324
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325 // Custom sections in wasm also have a string identifier.
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326 if (SectionId == wasm::WASM_SEC_CUSTOM) {
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327 assert(Name);
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328 writeString(StringRef(Name));
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329 }
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330 }
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331
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332 // Now that the section is complete and we know how big it is, patch up the
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333 // section size field at the start of the section.
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334 void WasmObjectWriter::endSection(SectionBookkeeping &Section) {
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335 uint64_t Size = getStream().tell() - Section.ContentsOffset;
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336 if (uint32_t(Size) != Size)
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337 report_fatal_error("section size does not fit in a uint32_t");
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338
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339 DEBUG(dbgs() << "endSection size=" << Size << "\n");
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340
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341 // Write the final section size to the payload_len field, which follows
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342 // the section id byte.
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343 uint8_t Buffer[16];
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344 unsigned SizeLen = encodeULEB128(Size, Buffer, 5);
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345 assert(SizeLen == 5);
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346 getStream().pwrite((char *)Buffer, SizeLen, Section.SizeOffset);
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347 }
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348
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349 // Emit the Wasm header.
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350 void WasmObjectWriter::writeHeader(const MCAssembler &Asm) {
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351 writeBytes(StringRef(wasm::WasmMagic, sizeof(wasm::WasmMagic)));
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352 writeLE32(wasm::WasmVersion);
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353 }
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354
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355 void WasmObjectWriter::executePostLayoutBinding(MCAssembler &Asm,
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356 const MCAsmLayout &Layout) {
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357 }
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358
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359 void WasmObjectWriter::recordRelocation(MCAssembler &Asm,
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360 const MCAsmLayout &Layout,
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361 const MCFragment *Fragment,
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362 const MCFixup &Fixup, MCValue Target,
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363 uint64_t &FixedValue) {
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364 MCAsmBackend &Backend = Asm.getBackend();
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365 bool IsPCRel = Backend.getFixupKindInfo(Fixup.getKind()).Flags &
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366 MCFixupKindInfo::FKF_IsPCRel;
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367 const auto &FixupSection = cast<MCSectionWasm>(*Fragment->getParent());
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368 uint64_t C = Target.getConstant();
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369 uint64_t FixupOffset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
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370 MCContext &Ctx = Asm.getContext();
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371
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372 if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
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373 assert(RefB->getKind() == MCSymbolRefExpr::VK_None &&
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374 "Should not have constructed this");
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375
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376 // Let A, B and C being the components of Target and R be the location of
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377 // the fixup. If the fixup is not pcrel, we want to compute (A - B + C).
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378 // If it is pcrel, we want to compute (A - B + C - R).
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379
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380 // In general, Wasm has no relocations for -B. It can only represent (A + C)
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381 // or (A + C - R). If B = R + K and the relocation is not pcrel, we can
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382 // replace B to implement it: (A - R - K + C)
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383 if (IsPCRel) {
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384 Ctx.reportError(
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385 Fixup.getLoc(),
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386 "No relocation available to represent this relative expression");
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387 return;
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388 }
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389
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390 const auto &SymB = cast<MCSymbolWasm>(RefB->getSymbol());
|
|
|
391
|
|
|
392 if (SymB.isUndefined()) {
|
|
|
393 Ctx.reportError(Fixup.getLoc(),
|
|
|
394 Twine("symbol '") + SymB.getName() +
|
|
|
395 "' can not be undefined in a subtraction expression");
|
|
|
396 return;
|
|
|
397 }
|
|
|
398
|
|
|
399 assert(!SymB.isAbsolute() && "Should have been folded");
|
|
|
400 const MCSection &SecB = SymB.getSection();
|
|
|
401 if (&SecB != &FixupSection) {
|
|
|
402 Ctx.reportError(Fixup.getLoc(),
|
|
|
403 "Cannot represent a difference across sections");
|
|
|
404 return;
|
|
|
405 }
|
|
|
406
|
|
|
407 uint64_t SymBOffset = Layout.getSymbolOffset(SymB);
|
|
|
408 uint64_t K = SymBOffset - FixupOffset;
|
|
|
409 IsPCRel = true;
|
|
|
410 C -= K;
|
|
|
411 }
|
|
|
412
|
|
|
413 // We either rejected the fixup or folded B into C at this point.
|
|
|
414 const MCSymbolRefExpr *RefA = Target.getSymA();
|
|
|
415 const auto *SymA = RefA ? cast<MCSymbolWasm>(&RefA->getSymbol()) : nullptr;
|
|
|
416
|
|
|
417 if (SymA && SymA->isVariable()) {
|
|
|
418 const MCExpr *Expr = SymA->getVariableValue();
|
|
|
419 const auto *Inner = cast<MCSymbolRefExpr>(Expr);
|
|
|
420 if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF)
|
|
|
421 llvm_unreachable("weakref used in reloc not yet implemented");
|
|
|
422 }
|
|
|
423
|
|
|
424 // Put any constant offset in an addend. Offsets can be negative, and
|
|
|
425 // LLVM expects wrapping, in contrast to wasm's immediates which can't
|
|
|
426 // be negative and don't wrap.
|
|
|
427 FixedValue = 0;
|
|
|
428
|
|
|
429 if (SymA)
|
|
|
430 SymA->setUsedInReloc();
|
|
|
431
|
|
|
432 assert(!IsPCRel);
|
|
|
433 assert(SymA);
|
|
|
434
|
|
|
435 unsigned Type = getRelocType(Target, Fixup);
|
|
|
436
|
|
|
437 WasmRelocationEntry Rec(FixupOffset, SymA, C, Type, &FixupSection);
|
|
|
438 DEBUG(dbgs() << "WasmReloc: " << Rec << "\n");
|
|
|
439
|
|
|
440 if (FixupSection.isWasmData())
|
|
|
441 DataRelocations.push_back(Rec);
|
|
|
442 else if (FixupSection.getKind().isText())
|
|
|
443 CodeRelocations.push_back(Rec);
|
|
|
444 else if (!FixupSection.getKind().isMetadata())
|
|
|
445 // TODO(sbc): Add support for debug sections.
|
|
|
446 llvm_unreachable("unexpected section type");
|
|
|
447 }
|
|
|
448
|
|
|
449 // Write X as an (unsigned) LEB value at offset Offset in Stream, padded
|
|
|
450 // to allow patching.
|
|
|
451 static void
|
|
|
452 WritePatchableLEB(raw_pwrite_stream &Stream, uint32_t X, uint64_t Offset) {
|
|
|
453 uint8_t Buffer[5];
|
|
|
454 unsigned SizeLen = encodeULEB128(X, Buffer, 5);
|
|
|
455 assert(SizeLen == 5);
|
|
|
456 Stream.pwrite((char *)Buffer, SizeLen, Offset);
|
|
|
457 }
|
|
|
458
|
|
|
459 // Write X as an signed LEB value at offset Offset in Stream, padded
|
|
|
460 // to allow patching.
|
|
|
461 static void
|
|
|
462 WritePatchableSLEB(raw_pwrite_stream &Stream, int32_t X, uint64_t Offset) {
|
|
|
463 uint8_t Buffer[5];
|
|
|
464 unsigned SizeLen = encodeSLEB128(X, Buffer, 5);
|
|
|
465 assert(SizeLen == 5);
|
|
|
466 Stream.pwrite((char *)Buffer, SizeLen, Offset);
|
|
|
467 }
|
|
|
468
|
|
|
469 // Write X as a plain integer value at offset Offset in Stream.
|
|
|
470 static void WriteI32(raw_pwrite_stream &Stream, uint32_t X, uint64_t Offset) {
|
|
|
471 uint8_t Buffer[4];
|
|
|
472 support::endian::write32le(Buffer, X);
|
|
|
473 Stream.pwrite((char *)Buffer, sizeof(Buffer), Offset);
|
|
|
474 }
|
|
|
475
|
|
|
476 static const MCSymbolWasm* ResolveSymbol(const MCSymbolWasm& Symbol) {
|
|
|
477 if (Symbol.isVariable()) {
|
|
|
478 const MCExpr *Expr = Symbol.getVariableValue();
|
|
|
479 auto *Inner = cast<MCSymbolRefExpr>(Expr);
|
|
|
480 return cast<MCSymbolWasm>(&Inner->getSymbol());
|
|
|
481 }
|
|
|
482 return &Symbol;
|
|
|
483 }
|
|
|
484
|
|
|
485 // Compute a value to write into the code at the location covered
|
|
|
486 // by RelEntry. This value isn't used by the static linker, since
|
|
|
487 // we have addends; it just serves to make the code more readable
|
|
|
488 // and to make standalone wasm modules directly usable.
|
|
|
489 uint32_t
|
|
|
490 WasmObjectWriter::getProvisionalValue(const WasmRelocationEntry &RelEntry) {
|
|
|
491 const MCSymbolWasm *Sym = ResolveSymbol(*RelEntry.Symbol);
|
|
|
492
|
|
|
493 // For undefined symbols, use a hopefully invalid value.
|
|
|
494 if (!Sym->isDefined(/*SetUsed=*/false))
|
|
|
495 return UINT32_MAX;
|
|
|
496
|
|
|
497 uint32_t GlobalIndex = SymbolIndices[Sym];
|
|
|
498 const WasmGlobal& Global = Globals[GlobalIndex - NumGlobalImports];
|
|
|
499 uint64_t Address = Global.InitialValue + RelEntry.Addend;
|
|
|
500
|
|
|
501 // Ignore overflow. LLVM allows address arithmetic to silently wrap.
|
|
|
502 uint32_t Value = Address;
|
|
|
503
|
|
|
504 return Value;
|
|
|
505 }
|
|
|
506
|
|
|
507 static void addData(SmallVectorImpl<char> &DataBytes,
|
|
|
508 MCSectionWasm &DataSection) {
|
|
|
509 DEBUG(errs() << "addData: " << DataSection.getSectionName() << "\n");
|
|
|
510
|
|
|
511 DataBytes.resize(alignTo(DataBytes.size(), DataSection.getAlignment()));
|
|
|
512
|
|
|
513 size_t LastFragmentSize = 0;
|
|
|
514 for (const MCFragment &Frag : DataSection) {
|
|
|
515 if (Frag.hasInstructions())
|
|
|
516 report_fatal_error("only data supported in data sections");
|
|
|
517
|
|
|
518 if (auto *Align = dyn_cast<MCAlignFragment>(&Frag)) {
|
|
|
519 if (Align->getValueSize() != 1)
|
|
|
520 report_fatal_error("only byte values supported for alignment");
|
|
|
521 // If nops are requested, use zeros, as this is the data section.
|
|
|
522 uint8_t Value = Align->hasEmitNops() ? 0 : Align->getValue();
|
|
|
523 uint64_t Size = std::min<uint64_t>(alignTo(DataBytes.size(),
|
|
|
524 Align->getAlignment()),
|
|
|
525 DataBytes.size() +
|
|
|
526 Align->getMaxBytesToEmit());
|
|
|
527 DataBytes.resize(Size, Value);
|
|
|
528 } else if (auto *Fill = dyn_cast<MCFillFragment>(&Frag)) {
|
|
|
529 DataBytes.insert(DataBytes.end(), Fill->getSize(), Fill->getValue());
|
|
|
530 } else {
|
|
|
531 const auto &DataFrag = cast<MCDataFragment>(Frag);
|
|
|
532 const SmallVectorImpl<char> &Contents = DataFrag.getContents();
|
|
|
533
|
|
|
534 DataBytes.insert(DataBytes.end(), Contents.begin(), Contents.end());
|
|
|
535 LastFragmentSize = Contents.size();
|
|
|
536 }
|
|
|
537 }
|
|
|
538
|
|
|
539 // Don't allow empty segments, or segments that end with zero-sized
|
|
|
540 // fragment, otherwise the linker cannot map symbols to a unique
|
|
|
541 // data segment. This can be triggered by zero-sized structs
|
|
|
542 // See: test/MC/WebAssembly/bss.ll
|
|
|
543 if (LastFragmentSize == 0)
|
|
|
544 DataBytes.resize(DataBytes.size() + 1);
|
|
|
545 DEBUG(dbgs() << "addData -> " << DataBytes.size() << "\n");
|
|
|
546 }
|
|
|
547
|
|
|
548 uint32_t WasmObjectWriter::getRelocationIndexValue(
|
|
|
549 const WasmRelocationEntry &RelEntry) {
|
|
|
550 switch (RelEntry.Type) {
|
|
|
551 case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
|
|
|
552 case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32:
|
|
|
553 if (!IndirectSymbolIndices.count(RelEntry.Symbol))
|
|
|
554 report_fatal_error("symbol not found table index space: " +
|
|
|
555 RelEntry.Symbol->getName());
|
|
|
556 return IndirectSymbolIndices[RelEntry.Symbol];
|
|
|
557 case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
|
|
|
558 case wasm::R_WEBASSEMBLY_GLOBAL_INDEX_LEB:
|
|
|
559 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_LEB:
|
|
|
560 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
|
|
|
561 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32:
|
|
|
562 if (!SymbolIndices.count(RelEntry.Symbol))
|
|
|
563 report_fatal_error("symbol not found function/global index space: " +
|
|
|
564 RelEntry.Symbol->getName());
|
|
|
565 return SymbolIndices[RelEntry.Symbol];
|
|
|
566 case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB:
|
|
|
567 if (!TypeIndices.count(RelEntry.Symbol))
|
|
|
568 report_fatal_error("symbol not found in type index space: " +
|
|
|
569 RelEntry.Symbol->getName());
|
|
|
570 return TypeIndices[RelEntry.Symbol];
|
|
|
571 default:
|
|
|
572 llvm_unreachable("invalid relocation type");
|
|
|
573 }
|
|
|
574 }
|
|
|
575
|
|
|
576 // Apply the portions of the relocation records that we can handle ourselves
|
|
|
577 // directly.
|
|
|
578 void WasmObjectWriter::applyRelocations(
|
|
|
579 ArrayRef<WasmRelocationEntry> Relocations, uint64_t ContentsOffset) {
|
|
|
580 raw_pwrite_stream &Stream = getStream();
|
|
|
581 for (const WasmRelocationEntry &RelEntry : Relocations) {
|
|
|
582 uint64_t Offset = ContentsOffset +
|
|
|
583 RelEntry.FixupSection->getSectionOffset() +
|
|
|
584 RelEntry.Offset;
|
|
|
585
|
|
|
586 DEBUG(dbgs() << "applyRelocation: " << RelEntry << "\n");
|
|
|
587 switch (RelEntry.Type) {
|
|
|
588 case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
|
|
|
589 case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
|
|
|
590 case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB:
|
|
|
591 case wasm::R_WEBASSEMBLY_GLOBAL_INDEX_LEB: {
|
|
|
592 uint32_t Index = getRelocationIndexValue(RelEntry);
|
|
|
593 WritePatchableSLEB(Stream, Index, Offset);
|
|
|
594 break;
|
|
|
595 }
|
|
|
596 case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32: {
|
|
|
597 uint32_t Index = getRelocationIndexValue(RelEntry);
|
|
|
598 WriteI32(Stream, Index, Offset);
|
|
|
599 break;
|
|
|
600 }
|
|
|
601 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB: {
|
|
|
602 uint32_t Value = getProvisionalValue(RelEntry);
|
|
|
603 WritePatchableSLEB(Stream, Value, Offset);
|
|
|
604 break;
|
|
|
605 }
|
|
|
606 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_LEB: {
|
|
|
607 uint32_t Value = getProvisionalValue(RelEntry);
|
|
|
608 WritePatchableLEB(Stream, Value, Offset);
|
|
|
609 break;
|
|
|
610 }
|
|
|
611 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32: {
|
|
|
612 uint32_t Value = getProvisionalValue(RelEntry);
|
|
|
613 WriteI32(Stream, Value, Offset);
|
|
|
614 break;
|
|
|
615 }
|
|
|
616 default:
|
|
|
617 llvm_unreachable("invalid relocation type");
|
|
|
618 }
|
|
|
619 }
|
|
|
620 }
|
|
|
621
|
|
|
622 // Write out the portions of the relocation records that the linker will
|
|
|
623 // need to handle.
|
|
|
624 void WasmObjectWriter::writeRelocations(
|
|
|
625 ArrayRef<WasmRelocationEntry> Relocations) {
|
|
|
626 raw_pwrite_stream &Stream = getStream();
|
|
|
627 for (const WasmRelocationEntry& RelEntry : Relocations) {
|
|
|
628
|
|
|
629 uint64_t Offset = RelEntry.Offset +
|
|
|
630 RelEntry.FixupSection->getSectionOffset();
|
|
|
631 uint32_t Index = getRelocationIndexValue(RelEntry);
|
|
|
632
|
|
|
633 encodeULEB128(RelEntry.Type, Stream);
|
|
|
634 encodeULEB128(Offset, Stream);
|
|
|
635 encodeULEB128(Index, Stream);
|
|
|
636 if (RelEntry.hasAddend())
|
|
|
637 encodeSLEB128(RelEntry.Addend, Stream);
|
|
|
638 }
|
|
|
639 }
|
|
|
640
|
|
|
641 void WasmObjectWriter::writeTypeSection(
|
|
|
642 ArrayRef<WasmFunctionType> FunctionTypes) {
|
|
|
643 if (FunctionTypes.empty())
|
|
|
644 return;
|
|
|
645
|
|
|
646 SectionBookkeeping Section;
|
|
|
647 startSection(Section, wasm::WASM_SEC_TYPE);
|
|
|
648
|
|
|
649 encodeULEB128(FunctionTypes.size(), getStream());
|
|
|
650
|
|
|
651 for (const WasmFunctionType &FuncTy : FunctionTypes) {
|
|
|
652 encodeSLEB128(wasm::WASM_TYPE_FUNC, getStream());
|
|
|
653 encodeULEB128(FuncTy.Params.size(), getStream());
|
|
|
654 for (wasm::ValType Ty : FuncTy.Params)
|
|
|
655 writeValueType(Ty);
|
|
|
656 encodeULEB128(FuncTy.Returns.size(), getStream());
|
|
|
657 for (wasm::ValType Ty : FuncTy.Returns)
|
|
|
658 writeValueType(Ty);
|
|
|
659 }
|
|
|
660
|
|
|
661 endSection(Section);
|
|
|
662 }
|
|
|
663
|
|
|
664 void WasmObjectWriter::writeImportSection(ArrayRef<WasmImport> Imports) {
|
|
|
665 if (Imports.empty())
|
|
|
666 return;
|
|
|
667
|
|
|
668 SectionBookkeeping Section;
|
|
|
669 startSection(Section, wasm::WASM_SEC_IMPORT);
|
|
|
670
|
|
|
671 encodeULEB128(Imports.size(), getStream());
|
|
|
672 for (const WasmImport &Import : Imports) {
|
|
|
673 writeString(Import.ModuleName);
|
|
|
674 writeString(Import.FieldName);
|
|
|
675
|
|
|
676 encodeULEB128(Import.Kind, getStream());
|
|
|
677
|
|
|
678 switch (Import.Kind) {
|
|
|
679 case wasm::WASM_EXTERNAL_FUNCTION:
|
|
|
680 encodeULEB128(Import.Type, getStream());
|
|
|
681 break;
|
|
|
682 case wasm::WASM_EXTERNAL_GLOBAL:
|
|
|
683 encodeSLEB128(int32_t(Import.Type), getStream());
|
|
|
684 encodeULEB128(0, getStream()); // mutability
|
|
|
685 break;
|
|
|
686 default:
|
|
|
687 llvm_unreachable("unsupported import kind");
|
|
|
688 }
|
|
|
689 }
|
|
|
690
|
|
|
691 endSection(Section);
|
|
|
692 }
|
|
|
693
|
|
|
694 void WasmObjectWriter::writeFunctionSection(ArrayRef<WasmFunction> Functions) {
|
|
|
695 if (Functions.empty())
|
|
|
696 return;
|
|
|
697
|
|
|
698 SectionBookkeeping Section;
|
|
|
699 startSection(Section, wasm::WASM_SEC_FUNCTION);
|
|
|
700
|
|
|
701 encodeULEB128(Functions.size(), getStream());
|
|
|
702 for (const WasmFunction &Func : Functions)
|
|
|
703 encodeULEB128(Func.Type, getStream());
|
|
|
704
|
|
|
705 endSection(Section);
|
|
|
706 }
|
|
|
707
|
|
|
708 void WasmObjectWriter::writeTableSection(uint32_t NumElements) {
|
|
|
709 // For now, always emit the table section, since indirect calls are not
|
|
|
710 // valid without it. In the future, we could perhaps be more clever and omit
|
|
|
711 // it if there are no indirect calls.
|
|
|
712
|
|
|
713 SectionBookkeeping Section;
|
|
|
714 startSection(Section, wasm::WASM_SEC_TABLE);
|
|
|
715
|
|
|
716 encodeULEB128(1, getStream()); // The number of tables.
|
|
|
717 // Fixed to 1 for now.
|
|
|
718 encodeSLEB128(wasm::WASM_TYPE_ANYFUNC, getStream()); // Type of table
|
|
|
719 encodeULEB128(0, getStream()); // flags
|
|
|
720 encodeULEB128(NumElements, getStream()); // initial
|
|
|
721
|
|
|
722 endSection(Section);
|
|
|
723 }
|
|
|
724
|
|
|
725 void WasmObjectWriter::writeMemorySection(uint32_t DataSize) {
|
|
|
726 // For now, always emit the memory section, since loads and stores are not
|
|
|
727 // valid without it. In the future, we could perhaps be more clever and omit
|
|
|
728 // it if there are no loads or stores.
|
|
|
729 SectionBookkeeping Section;
|
|
|
730 uint32_t NumPages = (DataSize + wasm::WasmPageSize - 1) / wasm::WasmPageSize;
|
|
|
731
|
|
|
732 startSection(Section, wasm::WASM_SEC_MEMORY);
|
|
|
733 encodeULEB128(1, getStream()); // number of memory spaces
|
|
|
734
|
|
|
735 encodeULEB128(0, getStream()); // flags
|
|
|
736 encodeULEB128(NumPages, getStream()); // initial
|
|
|
737
|
|
|
738 endSection(Section);
|
|
|
739 }
|
|
|
740
|
|
|
741 void WasmObjectWriter::writeGlobalSection() {
|
|
|
742 if (Globals.empty())
|
|
|
743 return;
|
|
|
744
|
|
|
745 SectionBookkeeping Section;
|
|
|
746 startSection(Section, wasm::WASM_SEC_GLOBAL);
|
|
|
747
|
|
|
748 encodeULEB128(Globals.size(), getStream());
|
|
|
749 for (const WasmGlobal &Global : Globals) {
|
|
|
750 writeValueType(Global.Type);
|
|
|
751 write8(Global.IsMutable);
|
|
|
752
|
|
|
753 if (Global.HasImport) {
|
|
|
754 assert(Global.InitialValue == 0);
|
|
|
755 write8(wasm::WASM_OPCODE_GET_GLOBAL);
|
|
|
756 encodeULEB128(Global.ImportIndex, getStream());
|
|
|
757 } else {
|
|
|
758 assert(Global.ImportIndex == 0);
|
|
|
759 write8(wasm::WASM_OPCODE_I32_CONST);
|
|
|
760 encodeSLEB128(Global.InitialValue, getStream()); // offset
|
|
|
761 }
|
|
|
762 write8(wasm::WASM_OPCODE_END);
|
|
|
763 }
|
|
|
764
|
|
|
765 endSection(Section);
|
|
|
766 }
|
|
|
767
|
|
|
768 void WasmObjectWriter::writeExportSection(ArrayRef<WasmExport> Exports) {
|
|
|
769 if (Exports.empty())
|
|
|
770 return;
|
|
|
771
|
|
|
772 SectionBookkeeping Section;
|
|
|
773 startSection(Section, wasm::WASM_SEC_EXPORT);
|
|
|
774
|
|
|
775 encodeULEB128(Exports.size(), getStream());
|
|
|
776 for (const WasmExport &Export : Exports) {
|
|
|
777 writeString(Export.FieldName);
|
|
|
778 encodeSLEB128(Export.Kind, getStream());
|
|
|
779 encodeULEB128(Export.Index, getStream());
|
|
|
780 }
|
|
|
781
|
|
|
782 endSection(Section);
|
|
|
783 }
|
|
|
784
|
|
|
785 void WasmObjectWriter::writeElemSection(ArrayRef<uint32_t> TableElems) {
|
|
|
786 if (TableElems.empty())
|
|
|
787 return;
|
|
|
788
|
|
|
789 SectionBookkeeping Section;
|
|
|
790 startSection(Section, wasm::WASM_SEC_ELEM);
|
|
|
791
|
|
|
792 encodeULEB128(1, getStream()); // number of "segments"
|
|
|
793 encodeULEB128(0, getStream()); // the table index
|
|
|
794
|
|
|
795 // init expr for starting offset
|
|
|
796 write8(wasm::WASM_OPCODE_I32_CONST);
|
|
|
797 encodeSLEB128(0, getStream());
|
|
|
798 write8(wasm::WASM_OPCODE_END);
|
|
|
799
|
|
|
800 encodeULEB128(TableElems.size(), getStream());
|
|
|
801 for (uint32_t Elem : TableElems)
|
|
|
802 encodeULEB128(Elem, getStream());
|
|
|
803
|
|
|
804 endSection(Section);
|
|
|
805 }
|
|
|
806
|
|
|
807 void WasmObjectWriter::writeCodeSection(const MCAssembler &Asm,
|
|
|
808 const MCAsmLayout &Layout,
|
|
|
809 ArrayRef<WasmFunction> Functions) {
|
|
|
810 if (Functions.empty())
|
|
|
811 return;
|
|
|
812
|
|
|
813 SectionBookkeeping Section;
|
|
|
814 startSection(Section, wasm::WASM_SEC_CODE);
|
|
|
815
|
|
|
816 encodeULEB128(Functions.size(), getStream());
|
|
|
817
|
|
|
818 for (const WasmFunction &Func : Functions) {
|
|
|
819 auto &FuncSection = static_cast<MCSectionWasm &>(Func.Sym->getSection());
|
|
|
820
|
|
|
821 int64_t Size = 0;
|
|
|
822 if (!Func.Sym->getSize()->evaluateAsAbsolute(Size, Layout))
|
|
|
823 report_fatal_error(".size expression must be evaluatable");
|
|
|
824
|
|
|
825 encodeULEB128(Size, getStream());
|
|
|
826 FuncSection.setSectionOffset(getStream().tell() - Section.ContentsOffset);
|
|
|
827 Asm.writeSectionData(&FuncSection, Layout);
|
|
|
828 }
|
|
|
829
|
|
|
830 // Apply fixups.
|
|
|
831 applyRelocations(CodeRelocations, Section.ContentsOffset);
|
|
|
832
|
|
|
833 endSection(Section);
|
|
|
834 }
|
|
|
835
|
|
|
836 void WasmObjectWriter::writeDataSection(ArrayRef<WasmDataSegment> Segments) {
|
|
|
837 if (Segments.empty())
|
|
|
838 return;
|
|
|
839
|
|
|
840 SectionBookkeeping Section;
|
|
|
841 startSection(Section, wasm::WASM_SEC_DATA);
|
|
|
842
|
|
|
843 encodeULEB128(Segments.size(), getStream()); // count
|
|
|
844
|
|
|
845 for (const WasmDataSegment & Segment : Segments) {
|
|
|
846 encodeULEB128(0, getStream()); // memory index
|
|
|
847 write8(wasm::WASM_OPCODE_I32_CONST);
|
|
|
848 encodeSLEB128(Segment.Offset, getStream()); // offset
|
|
|
849 write8(wasm::WASM_OPCODE_END);
|
|
|
850 encodeULEB128(Segment.Data.size(), getStream()); // size
|
|
|
851 Segment.Section->setSectionOffset(getStream().tell() - Section.ContentsOffset);
|
|
|
852 writeBytes(Segment.Data); // data
|
|
|
853 }
|
|
|
854
|
|
|
855 // Apply fixups.
|
|
|
856 applyRelocations(DataRelocations, Section.ContentsOffset);
|
|
|
857
|
|
|
858 endSection(Section);
|
|
|
859 }
|
|
|
860
|
|
|
861 void WasmObjectWriter::writeNameSection(
|
|
|
862 ArrayRef<WasmFunction> Functions,
|
|
|
863 ArrayRef<WasmImport> Imports,
|
|
|
864 unsigned NumFuncImports) {
|
|
|
865 uint32_t TotalFunctions = NumFuncImports + Functions.size();
|
|
|
866 if (TotalFunctions == 0)
|
|
|
867 return;
|
|
|
868
|
|
|
869 SectionBookkeeping Section;
|
|
|
870 startSection(Section, wasm::WASM_SEC_CUSTOM, "name");
|
|
|
871 SectionBookkeeping SubSection;
|
|
|
872 startSection(SubSection, wasm::WASM_NAMES_FUNCTION);
|
|
|
873
|
|
|
874 encodeULEB128(TotalFunctions, getStream());
|
|
|
875 uint32_t Index = 0;
|
|
|
876 for (const WasmImport &Import : Imports) {
|
|
|
877 if (Import.Kind == wasm::WASM_EXTERNAL_FUNCTION) {
|
|
|
878 encodeULEB128(Index, getStream());
|
|
|
879 writeString(Import.FieldName);
|
|
|
880 ++Index;
|
|
|
881 }
|
|
|
882 }
|
|
|
883 for (const WasmFunction &Func : Functions) {
|
|
|
884 encodeULEB128(Index, getStream());
|
|
|
885 writeString(Func.Sym->getName());
|
|
|
886 ++Index;
|
|
|
887 }
|
|
|
888
|
|
|
889 endSection(SubSection);
|
|
|
890 endSection(Section);
|
|
|
891 }
|
|
|
892
|
|
|
893 void WasmObjectWriter::writeCodeRelocSection() {
|
|
|
894 // See: https://github.com/WebAssembly/tool-conventions/blob/master/Linking.md
|
|
|
895 // for descriptions of the reloc sections.
|
|
|
896
|
|
|
897 if (CodeRelocations.empty())
|
|
|
898 return;
|
|
|
899
|
|
|
900 SectionBookkeeping Section;
|
|
|
901 startSection(Section, wasm::WASM_SEC_CUSTOM, "reloc.CODE");
|
|
|
902
|
|
|
903 encodeULEB128(wasm::WASM_SEC_CODE, getStream());
|
|
|
904 encodeULEB128(CodeRelocations.size(), getStream());
|
|
|
905
|
|
|
906 writeRelocations(CodeRelocations);
|
|
|
907
|
|
|
908 endSection(Section);
|
|
|
909 }
|
|
|
910
|
|
|
911 void WasmObjectWriter::writeDataRelocSection() {
|
|
|
912 // See: https://github.com/WebAssembly/tool-conventions/blob/master/Linking.md
|
|
|
913 // for descriptions of the reloc sections.
|
|
|
914
|
|
|
915 if (DataRelocations.empty())
|
|
|
916 return;
|
|
|
917
|
|
|
918 SectionBookkeeping Section;
|
|
|
919 startSection(Section, wasm::WASM_SEC_CUSTOM, "reloc.DATA");
|
|
|
920
|
|
|
921 encodeULEB128(wasm::WASM_SEC_DATA, getStream());
|
|
|
922 encodeULEB128(DataRelocations.size(), getStream());
|
|
|
923
|
|
|
924 writeRelocations(DataRelocations);
|
|
|
925
|
|
|
926 endSection(Section);
|
|
|
927 }
|
|
|
928
|
|
|
929 void WasmObjectWriter::writeLinkingMetaDataSection(
|
|
|
930 ArrayRef<WasmDataSegment> Segments, uint32_t DataSize,
|
|
|
931 SmallVector<std::pair<StringRef, uint32_t>, 4> SymbolFlags,
|
|
|
932 bool HasStackPointer, uint32_t StackPointerGlobal) {
|
|
|
933 SectionBookkeeping Section;
|
|
|
934 startSection(Section, wasm::WASM_SEC_CUSTOM, "linking");
|
|
|
935 SectionBookkeeping SubSection;
|
|
|
936
|
|
|
937 if (HasStackPointer) {
|
|
|
938 startSection(SubSection, wasm::WASM_STACK_POINTER);
|
|
|
939 encodeULEB128(StackPointerGlobal, getStream()); // id
|
|
|
940 endSection(SubSection);
|
|
|
941 }
|
|
|
942
|
|
|
943 if (SymbolFlags.size() != 0) {
|
|
|
944 startSection(SubSection, wasm::WASM_SYMBOL_INFO);
|
|
|
945 encodeULEB128(SymbolFlags.size(), getStream());
|
|
|
946 for (auto Pair: SymbolFlags) {
|
|
|
947 writeString(Pair.first);
|
|
|
948 encodeULEB128(Pair.second, getStream());
|
|
|
949 }
|
|
|
950 endSection(SubSection);
|
|
|
951 }
|
|
|
952
|
|
|
953 if (DataSize > 0) {
|
|
|
954 startSection(SubSection, wasm::WASM_DATA_SIZE);
|
|
|
955 encodeULEB128(DataSize, getStream());
|
|
|
956 endSection(SubSection);
|
|
|
957 }
|
|
|
958
|
|
|
959 if (Segments.size()) {
|
|
|
960 startSection(SubSection, wasm::WASM_SEGMENT_INFO);
|
|
|
961 encodeULEB128(Segments.size(), getStream());
|
|
|
962 for (const WasmDataSegment &Segment : Segments) {
|
|
|
963 writeString(Segment.Name);
|
|
|
964 encodeULEB128(Segment.Alignment, getStream());
|
|
|
965 encodeULEB128(Segment.Flags, getStream());
|
|
|
966 }
|
|
|
967 endSection(SubSection);
|
|
|
968 }
|
|
|
969
|
|
|
970 endSection(Section);
|
|
|
971 }
|
|
|
972
|
|
|
973 uint32_t WasmObjectWriter::getFunctionType(const MCSymbolWasm& Symbol) {
|
|
|
974 assert(Symbol.isFunction());
|
|
|
975 assert(TypeIndices.count(&Symbol));
|
|
|
976 return TypeIndices[&Symbol];
|
|
|
977 }
|
|
|
978
|
|
|
979 uint32_t WasmObjectWriter::registerFunctionType(const MCSymbolWasm& Symbol) {
|
|
|
980 assert(Symbol.isFunction());
|
|
|
981
|
|
|
982 WasmFunctionType F;
|
|
|
983 const MCSymbolWasm* ResolvedSym = ResolveSymbol(Symbol);
|
|
|
984 F.Returns = ResolvedSym->getReturns();
|
|
|
985 F.Params = ResolvedSym->getParams();
|
|
|
986
|
|
|
987 auto Pair =
|
|
|
988 FunctionTypeIndices.insert(std::make_pair(F, FunctionTypes.size()));
|
|
|
989 if (Pair.second)
|
|
|
990 FunctionTypes.push_back(F);
|
|
|
991 TypeIndices[&Symbol] = Pair.first->second;
|
|
|
992
|
|
|
993 DEBUG(dbgs() << "registerFunctionType: " << Symbol << " new:" << Pair.second << "\n");
|
|
|
994 DEBUG(dbgs() << " -> type index: " << Pair.first->second << "\n");
|
|
|
995 return Pair.first->second;
|
|
|
996 }
|
|
|
997
|
|
|
998 void WasmObjectWriter::writeObject(MCAssembler &Asm,
|
|
|
999 const MCAsmLayout &Layout) {
|
|
|
1000 DEBUG(dbgs() << "WasmObjectWriter::writeObject\n");
|
|
|
1001 MCContext &Ctx = Asm.getContext();
|
|
|
1002 wasm::ValType PtrType = is64Bit() ? wasm::ValType::I64 : wasm::ValType::I32;
|
|
|
1003
|
|
|
1004 // Collect information from the available symbols.
|
|
|
1005 SmallVector<WasmFunction, 4> Functions;
|
|
|
1006 SmallVector<uint32_t, 4> TableElems;
|
|
|
1007 SmallVector<WasmImport, 4> Imports;
|
|
|
1008 SmallVector<WasmExport, 4> Exports;
|
|
|
1009 SmallVector<std::pair<StringRef, uint32_t>, 4> SymbolFlags;
|
|
|
1010 SmallPtrSet<const MCSymbolWasm *, 4> IsAddressTaken;
|
|
|
1011 unsigned NumFuncImports = 0;
|
|
|
1012 SmallVector<WasmDataSegment, 4> DataSegments;
|
|
|
1013 uint32_t StackPointerGlobal = 0;
|
|
|
1014 uint32_t DataSize = 0;
|
|
|
1015 bool HasStackPointer = false;
|
|
|
1016
|
|
|
1017 // Populate the IsAddressTaken set.
|
|
|
1018 for (const WasmRelocationEntry &RelEntry : CodeRelocations) {
|
|
|
1019 switch (RelEntry.Type) {
|
|
|
1020 case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
|
|
|
1021 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
|
|
|
1022 IsAddressTaken.insert(RelEntry.Symbol);
|
|
|
1023 break;
|
|
|
1024 default:
|
|
|
1025 break;
|
|
|
1026 }
|
|
|
1027 }
|
|
|
1028 for (const WasmRelocationEntry &RelEntry : DataRelocations) {
|
|
|
1029 switch (RelEntry.Type) {
|
|
|
1030 case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32:
|
|
|
1031 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32:
|
|
|
1032 IsAddressTaken.insert(RelEntry.Symbol);
|
|
|
1033 break;
|
|
|
1034 default:
|
|
|
1035 break;
|
|
|
1036 }
|
|
|
1037 }
|
|
|
1038
|
|
|
1039 // Populate FunctionTypeIndices and Imports.
|
|
|
1040 for (const MCSymbol &S : Asm.symbols()) {
|
|
|
1041 const auto &WS = static_cast<const MCSymbolWasm &>(S);
|
|
|
1042
|
|
|
1043 if (WS.isTemporary())
|
|
|
1044 continue;
|
|
|
1045
|
|
|
1046 if (WS.isFunction())
|
|
|
1047 registerFunctionType(WS);
|
|
|
1048
|
|
|
1049 // If the symbol is not defined in this translation unit, import it.
|
|
|
1050 if (!WS.isDefined(/*SetUsed=*/false)) {
|
|
|
1051 WasmImport Import;
|
|
|
1052 Import.ModuleName = WS.getModuleName();
|
|
|
1053 Import.FieldName = WS.getName();
|
|
|
1054
|
|
|
1055 if (WS.isFunction()) {
|
|
|
1056 Import.Kind = wasm::WASM_EXTERNAL_FUNCTION;
|
|
|
1057 Import.Type = getFunctionType(WS);
|
|
|
1058 SymbolIndices[&WS] = NumFuncImports;
|
|
|
1059 ++NumFuncImports;
|
|
|
1060 } else {
|
|
|
1061 Import.Kind = wasm::WASM_EXTERNAL_GLOBAL;
|
|
|
1062 Import.Type = int32_t(PtrType);
|
|
|
1063 SymbolIndices[&WS] = NumGlobalImports;
|
|
|
1064 ++NumGlobalImports;
|
|
|
1065 }
|
|
|
1066
|
|
|
1067 Imports.push_back(Import);
|
|
|
1068 }
|
|
|
1069 }
|
|
|
1070
|
|
|
1071 // In the special .global_variables section, we've encoded global
|
|
|
1072 // variables used by the function. Translate them into the Globals
|
|
|
1073 // list.
|
|
|
1074 MCSectionWasm *GlobalVars =
|
|
|
1075 Ctx.getWasmSection(".global_variables", SectionKind::getMetadata());
|
|
|
1076 if (!GlobalVars->getFragmentList().empty()) {
|
|
|
1077 if (GlobalVars->getFragmentList().size() != 1)
|
|
|
1078 report_fatal_error("only one .global_variables fragment supported");
|
|
|
1079 const MCFragment &Frag = *GlobalVars->begin();
|
|
|
1080 if (Frag.hasInstructions() || Frag.getKind() != MCFragment::FT_Data)
|
|
|
1081 report_fatal_error("only data supported in .global_variables");
|
|
|
1082 const auto &DataFrag = cast<MCDataFragment>(Frag);
|
|
|
1083 if (!DataFrag.getFixups().empty())
|
|
|
1084 report_fatal_error("fixups not supported in .global_variables");
|
|
|
1085 const SmallVectorImpl<char> &Contents = DataFrag.getContents();
|
|
|
1086 for (const uint8_t *p = (const uint8_t *)Contents.data(),
|
|
|
1087 *end = (const uint8_t *)Contents.data() + Contents.size();
|
|
|
1088 p != end; ) {
|
|
|
1089 WasmGlobal G;
|
|
|
1090 if (end - p < 3)
|
|
|
1091 report_fatal_error("truncated global variable encoding");
|
|
|
1092 G.Type = wasm::ValType(int8_t(*p++));
|
|
|
1093 G.IsMutable = bool(*p++);
|
|
|
1094 G.HasImport = bool(*p++);
|
|
|
1095 if (G.HasImport) {
|
|
|
1096 G.InitialValue = 0;
|
|
|
1097
|
|
|
1098 WasmImport Import;
|
|
|
1099 Import.ModuleName = (const char *)p;
|
|
|
1100 const uint8_t *nul = (const uint8_t *)memchr(p, '\0', end - p);
|
|
|
1101 if (!nul)
|
|
|
1102 report_fatal_error("global module name must be nul-terminated");
|
|
|
1103 p = nul + 1;
|
|
|
1104 nul = (const uint8_t *)memchr(p, '\0', end - p);
|
|
|
1105 if (!nul)
|
|
|
1106 report_fatal_error("global base name must be nul-terminated");
|
|
|
1107 Import.FieldName = (const char *)p;
|
|
|
1108 p = nul + 1;
|
|
|
1109
|
|
|
1110 Import.Kind = wasm::WASM_EXTERNAL_GLOBAL;
|
|
|
1111 Import.Type = int32_t(G.Type);
|
|
|
1112
|
|
|
1113 G.ImportIndex = NumGlobalImports;
|
|
|
1114 ++NumGlobalImports;
|
|
|
1115
|
|
|
1116 Imports.push_back(Import);
|
|
|
1117 } else {
|
|
|
1118 unsigned n;
|
|
|
1119 G.InitialValue = decodeSLEB128(p, &n);
|
|
|
1120 G.ImportIndex = 0;
|
|
|
1121 if ((ptrdiff_t)n > end - p)
|
|
|
1122 report_fatal_error("global initial value must be valid SLEB128");
|
|
|
1123 p += n;
|
|
|
1124 }
|
|
|
1125 Globals.push_back(G);
|
|
|
1126 }
|
|
|
1127 }
|
|
|
1128
|
|
|
1129 // In the special .stack_pointer section, we've encoded the stack pointer
|
|
|
1130 // index.
|
|
|
1131 MCSectionWasm *StackPtr =
|
|
|
1132 Ctx.getWasmSection(".stack_pointer", SectionKind::getMetadata());
|
|
|
1133 if (!StackPtr->getFragmentList().empty()) {
|
|
|
1134 if (StackPtr->getFragmentList().size() != 1)
|
|
|
1135 report_fatal_error("only one .stack_pointer fragment supported");
|
|
|
1136 const MCFragment &Frag = *StackPtr->begin();
|
|
|
1137 if (Frag.hasInstructions() || Frag.getKind() != MCFragment::FT_Data)
|
|
|
1138 report_fatal_error("only data supported in .stack_pointer");
|
|
|
1139 const auto &DataFrag = cast<MCDataFragment>(Frag);
|
|
|
1140 if (!DataFrag.getFixups().empty())
|
|
|
1141 report_fatal_error("fixups not supported in .stack_pointer");
|
|
|
1142 const SmallVectorImpl<char> &Contents = DataFrag.getContents();
|
|
|
1143 if (Contents.size() != 4)
|
|
|
1144 report_fatal_error("only one entry supported in .stack_pointer");
|
|
|
1145 HasStackPointer = true;
|
|
|
1146 StackPointerGlobal = NumGlobalImports + *(const int32_t *)Contents.data();
|
|
|
1147 }
|
|
|
1148
|
|
|
1149 for (MCSection &Sec : Asm) {
|
|
|
1150 auto &Section = static_cast<MCSectionWasm &>(Sec);
|
|
|
1151 if (!Section.isWasmData())
|
|
|
1152 continue;
|
|
|
1153
|
|
|
1154 DataSize = alignTo(DataSize, Section.getAlignment());
|
|
|
1155 DataSegments.emplace_back();
|
|
|
1156 WasmDataSegment &Segment = DataSegments.back();
|
|
|
1157 Segment.Name = Section.getSectionName();
|
|
|
1158 Segment.Offset = DataSize;
|
|
|
1159 Segment.Section = &Section;
|
|
|
1160 addData(Segment.Data, Section);
|
|
|
1161 Segment.Alignment = Section.getAlignment();
|
|
|
1162 Segment.Flags = 0;
|
|
|
1163 DataSize += Segment.Data.size();
|
|
|
1164 Section.setMemoryOffset(Segment.Offset);
|
|
|
1165 }
|
|
|
1166
|
|
|
1167 // Handle regular defined and undefined symbols.
|
|
|
1168 for (const MCSymbol &S : Asm.symbols()) {
|
|
|
1169 // Ignore unnamed temporary symbols, which aren't ever exported, imported,
|
|
|
1170 // or used in relocations.
|
|
|
1171 if (S.isTemporary() && S.getName().empty())
|
|
|
1172 continue;
|
|
|
1173
|
|
|
1174 const auto &WS = static_cast<const MCSymbolWasm &>(S);
|
|
|
1175 DEBUG(dbgs() << "MCSymbol: '" << S << "'"
|
|
|
1176 << " isDefined=" << S.isDefined() << " isExternal="
|
|
|
1177 << S.isExternal() << " isTemporary=" << S.isTemporary()
|
|
|
1178 << " isFunction=" << WS.isFunction()
|
|
|
1179 << " isWeak=" << WS.isWeak()
|
|
|
1180 << " isVariable=" << WS.isVariable() << "\n");
|
|
|
1181
|
|
|
1182 if (WS.isWeak())
|
|
|
1183 SymbolFlags.emplace_back(WS.getName(), wasm::WASM_SYMBOL_BINDING_WEAK);
|
|
|
1184
|
|
|
1185 if (WS.isVariable())
|
|
|
1186 continue;
|
|
|
1187
|
|
|
1188 unsigned Index;
|
|
|
1189
|
|
|
1190 if (WS.isFunction()) {
|
|
|
1191 if (WS.isDefined(/*SetUsed=*/false)) {
|
|
|
1192 if (WS.getOffset() != 0)
|
|
|
1193 report_fatal_error(
|
|
|
1194 "function sections must contain one function each");
|
|
|
1195
|
|
|
1196 if (WS.getSize() == 0)
|
|
|
1197 report_fatal_error(
|
|
|
1198 "function symbols must have a size set with .size");
|
|
|
1199
|
|
|
1200 // A definition. Take the next available index.
|
|
|
1201 Index = NumFuncImports + Functions.size();
|
|
|
1202
|
|
|
1203 // Prepare the function.
|
|
|
1204 WasmFunction Func;
|
|
|
1205 Func.Type = getFunctionType(WS);
|
|
|
1206 Func.Sym = &WS;
|
|
|
1207 SymbolIndices[&WS] = Index;
|
|
|
1208 Functions.push_back(Func);
|
|
|
1209 } else {
|
|
|
1210 // An import; the index was assigned above.
|
|
|
1211 Index = SymbolIndices.find(&WS)->second;
|
|
|
1212 }
|
|
|
1213
|
|
|
1214 DEBUG(dbgs() << " -> function index: " << Index << "\n");
|
|
|
1215
|
|
|
1216 // If needed, prepare the function to be called indirectly.
|
|
|
1217 if (IsAddressTaken.count(&WS) != 0) {
|
|
|
1218 IndirectSymbolIndices[&WS] = TableElems.size();
|
|
|
1219 DEBUG(dbgs() << " -> adding to table: " << TableElems.size() << "\n");
|
|
|
1220 TableElems.push_back(Index);
|
|
|
1221 }
|
|
|
1222 } else {
|
|
|
1223 if (WS.isTemporary() && !WS.getSize())
|
|
|
1224 continue;
|
|
|
1225
|
|
|
1226 if (!WS.isDefined(/*SetUsed=*/false))
|
|
|
1227 continue;
|
|
|
1228
|
|
|
1229 if (!WS.getSize())
|
|
|
1230 report_fatal_error("data symbols must have a size set with .size: " +
|
|
|
1231 WS.getName());
|
|
|
1232
|
|
|
1233 int64_t Size = 0;
|
|
|
1234 if (!WS.getSize()->evaluateAsAbsolute(Size, Layout))
|
|
|
1235 report_fatal_error(".size expression must be evaluatable");
|
|
|
1236
|
|
|
1237 // For each global, prepare a corresponding wasm global holding its
|
|
|
1238 // address. For externals these will also be named exports.
|
|
|
1239 Index = NumGlobalImports + Globals.size();
|
|
|
1240 auto &DataSection = static_cast<MCSectionWasm &>(WS.getSection());
|
|
|
1241
|
|
|
1242 WasmGlobal Global;
|
|
|
1243 Global.Type = PtrType;
|
|
|
1244 Global.IsMutable = false;
|
|
|
1245 Global.HasImport = false;
|
|
|
1246 Global.InitialValue = DataSection.getMemoryOffset() + Layout.getSymbolOffset(WS);
|
|
|
1247 Global.ImportIndex = 0;
|
|
|
1248 SymbolIndices[&WS] = Index;
|
|
|
1249 DEBUG(dbgs() << " -> global index: " << Index << "\n");
|
|
|
1250 Globals.push_back(Global);
|
|
|
1251 }
|
|
|
1252
|
|
|
1253 // If the symbol is visible outside this translation unit, export it.
|
|
|
1254 if (WS.isDefined(/*SetUsed=*/false)) {
|
|
|
1255 WasmExport Export;
|
|
|
1256 Export.FieldName = WS.getName();
|
|
|
1257 Export.Index = Index;
|
|
|
1258 if (WS.isFunction())
|
|
|
1259 Export.Kind = wasm::WASM_EXTERNAL_FUNCTION;
|
|
|
1260 else
|
|
|
1261 Export.Kind = wasm::WASM_EXTERNAL_GLOBAL;
|
|
|
1262 DEBUG(dbgs() << " -> export " << Exports.size() << "\n");
|
|
|
1263 Exports.push_back(Export);
|
|
|
1264 if (!WS.isExternal())
|
|
|
1265 SymbolFlags.emplace_back(WS.getName(), wasm::WASM_SYMBOL_BINDING_LOCAL);
|
|
|
1266 }
|
|
|
1267 }
|
|
|
1268
|
|
|
1269 // Handle weak aliases. We need to process these in a separate pass because
|
|
|
1270 // we need to have processed the target of the alias before the alias itself
|
|
|
1271 // and the symbols are not necessarily ordered in this way.
|
|
|
1272 for (const MCSymbol &S : Asm.symbols()) {
|
|
|
1273 if (!S.isVariable())
|
|
|
1274 continue;
|
|
|
1275
|
|
|
1276 assert(S.isDefined(/*SetUsed=*/false));
|
|
|
1277
|
|
|
1278 // Find the target symbol of this weak alias and export that index
|
|
|
1279 const auto &WS = static_cast<const MCSymbolWasm &>(S);
|
|
|
1280 const MCSymbolWasm *ResolvedSym = ResolveSymbol(WS);
|
|
|
1281 DEBUG(dbgs() << WS.getName() << ": weak alias of '" << *ResolvedSym << "'\n");
|
|
|
1282 assert(SymbolIndices.count(ResolvedSym) > 0);
|
|
|
1283 uint32_t Index = SymbolIndices.find(ResolvedSym)->second;
|
|
|
1284 DEBUG(dbgs() << " -> index:" << Index << "\n");
|
|
|
1285
|
|
|
1286 SymbolIndices[&WS] = Index;
|
|
|
1287 WasmExport Export;
|
|
|
1288 Export.FieldName = WS.getName();
|
|
|
1289 Export.Index = Index;
|
|
|
1290 if (WS.isFunction())
|
|
|
1291 Export.Kind = wasm::WASM_EXTERNAL_FUNCTION;
|
|
|
1292 else
|
|
|
1293 Export.Kind = wasm::WASM_EXTERNAL_GLOBAL;
|
|
|
1294 DEBUG(dbgs() << " -> export " << Exports.size() << "\n");
|
|
|
1295 Exports.push_back(Export);
|
|
|
1296
|
|
|
1297 if (!WS.isExternal())
|
|
|
1298 SymbolFlags.emplace_back(WS.getName(), wasm::WASM_SYMBOL_BINDING_LOCAL);
|
|
|
1299 }
|
|
|
1300
|
|
|
1301 // Add types for indirect function calls.
|
|
|
1302 for (const WasmRelocationEntry &Fixup : CodeRelocations) {
|
|
|
1303 if (Fixup.Type != wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB)
|
|
|
1304 continue;
|
|
|
1305
|
|
|
1306 registerFunctionType(*Fixup.Symbol);
|
|
|
1307 }
|
|
|
1308
|
|
|
1309 // Write out the Wasm header.
|
|
|
1310 writeHeader(Asm);
|
|
|
1311
|
|
|
1312 writeTypeSection(FunctionTypes);
|
|
|
1313 writeImportSection(Imports);
|
|
|
1314 writeFunctionSection(Functions);
|
|
|
1315 writeTableSection(TableElems.size());
|
|
|
1316 writeMemorySection(DataSize);
|
|
|
1317 writeGlobalSection();
|
|
|
1318 writeExportSection(Exports);
|
|
|
1319 // TODO: Start Section
|
|
|
1320 writeElemSection(TableElems);
|
|
|
1321 writeCodeSection(Asm, Layout, Functions);
|
|
|
1322 writeDataSection(DataSegments);
|
|
|
1323 writeNameSection(Functions, Imports, NumFuncImports);
|
|
|
1324 writeCodeRelocSection();
|
|
|
1325 writeDataRelocSection();
|
|
|
1326 writeLinkingMetaDataSection(DataSegments, DataSize, SymbolFlags,
|
|
|
1327 HasStackPointer, StackPointerGlobal);
|
|
|
1328
|
|
|
1329 // TODO: Translate the .comment section to the output.
|
|
|
1330 // TODO: Translate debug sections to the output.
|
|
|
1331 }
|
|
|
1332
|
|
|
1333 std::unique_ptr<MCObjectWriter>
|
|
|
1334 llvm::createWasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW,
|
|
|
1335 raw_pwrite_stream &OS) {
|
|
|
1336 // FIXME: Can't use make_unique<WasmObjectWriter>(...) as WasmObjectWriter's
|
|
|
1337 // destructor is private. Is that necessary?
|
|
|
1338 return std::unique_ptr<MCObjectWriter>(
|
|
|
1339 new WasmObjectWriter(std::move(MOTW), OS));
|
|
|
1340 }
|
