| File: | llvm/lib/MC/WasmObjectWriter.cpp |
| Warning: | line 1565, column 11 Value stored to 'Index' is never read |
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| 1 | //===- lib/MC/WasmObjectWriter.cpp - Wasm File Writer ---------------------===// |
| 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 | // This file implements Wasm object file writer information. |
| 10 | // |
| 11 | //===----------------------------------------------------------------------===// |
| 12 | |
| 13 | #include "llvm/ADT/STLExtras.h" |
| 14 | #include "llvm/ADT/SmallPtrSet.h" |
| 15 | #include "llvm/BinaryFormat/Wasm.h" |
| 16 | #include "llvm/BinaryFormat/WasmTraits.h" |
| 17 | #include "llvm/Config/llvm-config.h" |
| 18 | #include "llvm/MC/MCAsmBackend.h" |
| 19 | #include "llvm/MC/MCAsmLayout.h" |
| 20 | #include "llvm/MC/MCAssembler.h" |
| 21 | #include "llvm/MC/MCContext.h" |
| 22 | #include "llvm/MC/MCExpr.h" |
| 23 | #include "llvm/MC/MCFixupKindInfo.h" |
| 24 | #include "llvm/MC/MCObjectWriter.h" |
| 25 | #include "llvm/MC/MCSectionWasm.h" |
| 26 | #include "llvm/MC/MCSymbolWasm.h" |
| 27 | #include "llvm/MC/MCValue.h" |
| 28 | #include "llvm/MC/MCWasmObjectWriter.h" |
| 29 | #include "llvm/Support/Casting.h" |
| 30 | #include "llvm/Support/Debug.h" |
| 31 | #include "llvm/Support/EndianStream.h" |
| 32 | #include "llvm/Support/ErrorHandling.h" |
| 33 | #include "llvm/Support/LEB128.h" |
| 34 | #include "llvm/Support/StringSaver.h" |
| 35 | #include <vector> |
| 36 | |
| 37 | using namespace llvm; |
| 38 | |
| 39 | #define DEBUG_TYPE"mc" "mc" |
| 40 | |
| 41 | namespace { |
| 42 | |
| 43 | // When we create the indirect function table we start at 1, so that there is |
| 44 | // and empty slot at 0 and therefore calling a null function pointer will trap. |
| 45 | static const uint32_t InitialTableOffset = 1; |
| 46 | |
| 47 | // For patching purposes, we need to remember where each section starts, both |
| 48 | // for patching up the section size field, and for patching up references to |
| 49 | // locations within the section. |
| 50 | struct SectionBookkeeping { |
| 51 | // Where the size of the section is written. |
| 52 | uint64_t SizeOffset; |
| 53 | // Where the section header ends (without custom section name). |
| 54 | uint64_t PayloadOffset; |
| 55 | // Where the contents of the section starts. |
| 56 | uint64_t ContentsOffset; |
| 57 | uint32_t Index; |
| 58 | }; |
| 59 | |
| 60 | // A wasm data segment. A wasm binary contains only a single data section |
| 61 | // but that can contain many segments, each with their own virtual location |
| 62 | // in memory. Each MCSection data created by llvm is modeled as its own |
| 63 | // wasm data segment. |
| 64 | struct WasmDataSegment { |
| 65 | MCSectionWasm *Section; |
| 66 | StringRef Name; |
| 67 | uint32_t InitFlags; |
| 68 | uint64_t Offset; |
| 69 | uint32_t Alignment; |
| 70 | uint32_t LinkingFlags; |
| 71 | SmallVector<char, 4> Data; |
| 72 | }; |
| 73 | |
| 74 | // A wasm function to be written into the function section. |
| 75 | struct WasmFunction { |
| 76 | uint32_t SigIndex; |
| 77 | const MCSymbolWasm *Sym; |
| 78 | }; |
| 79 | |
| 80 | // A wasm global to be written into the global section. |
| 81 | struct WasmGlobal { |
| 82 | wasm::WasmGlobalType Type; |
| 83 | uint64_t InitialValue; |
| 84 | }; |
| 85 | |
| 86 | // Information about a single item which is part of a COMDAT. For each data |
| 87 | // segment or function which is in the COMDAT, there is a corresponding |
| 88 | // WasmComdatEntry. |
| 89 | struct WasmComdatEntry { |
| 90 | unsigned Kind; |
| 91 | uint32_t Index; |
| 92 | }; |
| 93 | |
| 94 | // Information about a single relocation. |
| 95 | struct WasmRelocationEntry { |
| 96 | uint64_t Offset; // Where is the relocation. |
| 97 | const MCSymbolWasm *Symbol; // The symbol to relocate with. |
| 98 | int64_t Addend; // A value to add to the symbol. |
| 99 | unsigned Type; // The type of the relocation. |
| 100 | const MCSectionWasm *FixupSection; // The section the relocation is targeting. |
| 101 | |
| 102 | WasmRelocationEntry(uint64_t Offset, const MCSymbolWasm *Symbol, |
| 103 | int64_t Addend, unsigned Type, |
| 104 | const MCSectionWasm *FixupSection) |
| 105 | : Offset(Offset), Symbol(Symbol), Addend(Addend), Type(Type), |
| 106 | FixupSection(FixupSection) {} |
| 107 | |
| 108 | bool hasAddend() const { return wasm::relocTypeHasAddend(Type); } |
| 109 | |
| 110 | void print(raw_ostream &Out) const { |
| 111 | Out << wasm::relocTypetoString(Type) << " Off=" << Offset |
| 112 | << ", Sym=" << *Symbol << ", Addend=" << Addend |
| 113 | << ", FixupSection=" << FixupSection->getName(); |
| 114 | } |
| 115 | |
| 116 | #if !defined(NDEBUG1) || defined(LLVM_ENABLE_DUMP) |
| 117 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void dump() const { print(dbgs()); } |
| 118 | #endif |
| 119 | }; |
| 120 | |
| 121 | static const uint32_t InvalidIndex = -1; |
| 122 | |
| 123 | struct WasmCustomSection { |
| 124 | |
| 125 | StringRef Name; |
| 126 | MCSectionWasm *Section; |
| 127 | |
| 128 | uint32_t OutputContentsOffset; |
| 129 | uint32_t OutputIndex; |
| 130 | |
| 131 | WasmCustomSection(StringRef Name, MCSectionWasm *Section) |
| 132 | : Name(Name), Section(Section), OutputContentsOffset(0), |
| 133 | OutputIndex(InvalidIndex) {} |
| 134 | }; |
| 135 | |
| 136 | #if !defined(NDEBUG1) |
| 137 | raw_ostream &operator<<(raw_ostream &OS, const WasmRelocationEntry &Rel) { |
| 138 | Rel.print(OS); |
| 139 | return OS; |
| 140 | } |
| 141 | #endif |
| 142 | |
| 143 | // Write X as an (unsigned) LEB value at offset Offset in Stream, padded |
| 144 | // to allow patching. |
| 145 | template <int W> |
| 146 | void writePatchableLEB(raw_pwrite_stream &Stream, uint64_t X, uint64_t Offset) { |
| 147 | uint8_t Buffer[W]; |
| 148 | unsigned SizeLen = encodeULEB128(X, Buffer, W); |
| 149 | assert(SizeLen == W)(static_cast<void> (0)); |
| 150 | Stream.pwrite((char *)Buffer, SizeLen, Offset); |
| 151 | } |
| 152 | |
| 153 | // Write X as an signed LEB value at offset Offset in Stream, padded |
| 154 | // to allow patching. |
| 155 | template <int W> |
| 156 | void writePatchableSLEB(raw_pwrite_stream &Stream, int64_t X, uint64_t Offset) { |
| 157 | uint8_t Buffer[W]; |
| 158 | unsigned SizeLen = encodeSLEB128(X, Buffer, W); |
| 159 | assert(SizeLen == W)(static_cast<void> (0)); |
| 160 | Stream.pwrite((char *)Buffer, SizeLen, Offset); |
| 161 | } |
| 162 | |
| 163 | // Write X as a plain integer value at offset Offset in Stream. |
| 164 | static void patchI32(raw_pwrite_stream &Stream, uint32_t X, uint64_t Offset) { |
| 165 | uint8_t Buffer[4]; |
| 166 | support::endian::write32le(Buffer, X); |
| 167 | Stream.pwrite((char *)Buffer, sizeof(Buffer), Offset); |
| 168 | } |
| 169 | |
| 170 | static void patchI64(raw_pwrite_stream &Stream, uint64_t X, uint64_t Offset) { |
| 171 | uint8_t Buffer[8]; |
| 172 | support::endian::write64le(Buffer, X); |
| 173 | Stream.pwrite((char *)Buffer, sizeof(Buffer), Offset); |
| 174 | } |
| 175 | |
| 176 | bool isDwoSection(const MCSection &Sec) { |
| 177 | return Sec.getName().endswith(".dwo"); |
| 178 | } |
| 179 | |
| 180 | class WasmObjectWriter : public MCObjectWriter { |
| 181 | support::endian::Writer *W; |
| 182 | |
| 183 | /// The target specific Wasm writer instance. |
| 184 | std::unique_ptr<MCWasmObjectTargetWriter> TargetObjectWriter; |
| 185 | |
| 186 | // Relocations for fixing up references in the code section. |
| 187 | std::vector<WasmRelocationEntry> CodeRelocations; |
| 188 | // Relocations for fixing up references in the data section. |
| 189 | std::vector<WasmRelocationEntry> DataRelocations; |
| 190 | |
| 191 | // Index values to use for fixing up call_indirect type indices. |
| 192 | // Maps function symbols to the index of the type of the function |
| 193 | DenseMap<const MCSymbolWasm *, uint32_t> TypeIndices; |
| 194 | // Maps function symbols to the table element index space. Used |
| 195 | // for TABLE_INDEX relocation types (i.e. address taken functions). |
| 196 | DenseMap<const MCSymbolWasm *, uint32_t> TableIndices; |
| 197 | // Maps function/global/table symbols to the |
| 198 | // function/global/table/tag/section index space. |
| 199 | DenseMap<const MCSymbolWasm *, uint32_t> WasmIndices; |
| 200 | DenseMap<const MCSymbolWasm *, uint32_t> GOTIndices; |
| 201 | // Maps data symbols to the Wasm segment and offset/size with the segment. |
| 202 | DenseMap<const MCSymbolWasm *, wasm::WasmDataReference> DataLocations; |
| 203 | |
| 204 | // Stores output data (index, relocations, content offset) for custom |
| 205 | // section. |
| 206 | std::vector<WasmCustomSection> CustomSections; |
| 207 | std::unique_ptr<WasmCustomSection> ProducersSection; |
| 208 | std::unique_ptr<WasmCustomSection> TargetFeaturesSection; |
| 209 | // Relocations for fixing up references in the custom sections. |
| 210 | DenseMap<const MCSectionWasm *, std::vector<WasmRelocationEntry>> |
| 211 | CustomSectionsRelocations; |
| 212 | |
| 213 | // Map from section to defining function symbol. |
| 214 | DenseMap<const MCSection *, const MCSymbol *> SectionFunctions; |
| 215 | |
| 216 | DenseMap<wasm::WasmSignature, uint32_t> SignatureIndices; |
| 217 | SmallVector<wasm::WasmSignature, 4> Signatures; |
| 218 | SmallVector<WasmDataSegment, 4> DataSegments; |
| 219 | unsigned NumFunctionImports = 0; |
| 220 | unsigned NumGlobalImports = 0; |
| 221 | unsigned NumTableImports = 0; |
| 222 | unsigned NumTagImports = 0; |
| 223 | uint32_t SectionCount = 0; |
| 224 | |
| 225 | enum class DwoMode { |
| 226 | AllSections, |
| 227 | NonDwoOnly, |
| 228 | DwoOnly, |
| 229 | }; |
| 230 | bool IsSplitDwarf = false; |
| 231 | raw_pwrite_stream *OS = nullptr; |
| 232 | raw_pwrite_stream *DwoOS = nullptr; |
| 233 | |
| 234 | // TargetObjectWriter wranppers. |
| 235 | bool is64Bit() const { return TargetObjectWriter->is64Bit(); } |
| 236 | bool isEmscripten() const { return TargetObjectWriter->isEmscripten(); } |
| 237 | |
| 238 | void startSection(SectionBookkeeping &Section, unsigned SectionId); |
| 239 | void startCustomSection(SectionBookkeeping &Section, StringRef Name); |
| 240 | void endSection(SectionBookkeeping &Section); |
| 241 | |
| 242 | public: |
| 243 | WasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW, |
| 244 | raw_pwrite_stream &OS_) |
| 245 | : TargetObjectWriter(std::move(MOTW)), OS(&OS_) {} |
| 246 | |
| 247 | WasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW, |
| 248 | raw_pwrite_stream &OS_, raw_pwrite_stream &DwoOS_) |
| 249 | : TargetObjectWriter(std::move(MOTW)), IsSplitDwarf(true), OS(&OS_), |
| 250 | DwoOS(&DwoOS_) {} |
| 251 | |
| 252 | private: |
| 253 | void reset() override { |
| 254 | CodeRelocations.clear(); |
| 255 | DataRelocations.clear(); |
| 256 | TypeIndices.clear(); |
| 257 | WasmIndices.clear(); |
| 258 | GOTIndices.clear(); |
| 259 | TableIndices.clear(); |
| 260 | DataLocations.clear(); |
| 261 | CustomSections.clear(); |
| 262 | ProducersSection.reset(); |
| 263 | TargetFeaturesSection.reset(); |
| 264 | CustomSectionsRelocations.clear(); |
| 265 | SignatureIndices.clear(); |
| 266 | Signatures.clear(); |
| 267 | DataSegments.clear(); |
| 268 | SectionFunctions.clear(); |
| 269 | NumFunctionImports = 0; |
| 270 | NumGlobalImports = 0; |
| 271 | NumTableImports = 0; |
| 272 | MCObjectWriter::reset(); |
| 273 | } |
| 274 | |
| 275 | void writeHeader(const MCAssembler &Asm); |
| 276 | |
| 277 | void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout, |
| 278 | const MCFragment *Fragment, const MCFixup &Fixup, |
| 279 | MCValue Target, uint64_t &FixedValue) override; |
| 280 | |
| 281 | void executePostLayoutBinding(MCAssembler &Asm, |
| 282 | const MCAsmLayout &Layout) override; |
| 283 | void prepareImports(SmallVectorImpl<wasm::WasmImport> &Imports, |
| 284 | MCAssembler &Asm, const MCAsmLayout &Layout); |
| 285 | uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override; |
| 286 | |
| 287 | uint64_t writeOneObject(MCAssembler &Asm, const MCAsmLayout &Layout, |
| 288 | DwoMode Mode); |
| 289 | |
| 290 | void writeString(const StringRef Str) { |
| 291 | encodeULEB128(Str.size(), W->OS); |
| 292 | W->OS << Str; |
| 293 | } |
| 294 | |
| 295 | void writeI32(int32_t val) { |
| 296 | char Buffer[4]; |
| 297 | support::endian::write32le(Buffer, val); |
| 298 | W->OS.write(Buffer, sizeof(Buffer)); |
| 299 | } |
| 300 | |
| 301 | void writeI64(int64_t val) { |
| 302 | char Buffer[8]; |
| 303 | support::endian::write64le(Buffer, val); |
| 304 | W->OS.write(Buffer, sizeof(Buffer)); |
| 305 | } |
| 306 | |
| 307 | void writeValueType(wasm::ValType Ty) { W->OS << static_cast<char>(Ty); } |
| 308 | |
| 309 | void writeTypeSection(ArrayRef<wasm::WasmSignature> Signatures); |
| 310 | void writeImportSection(ArrayRef<wasm::WasmImport> Imports, uint64_t DataSize, |
| 311 | uint32_t NumElements); |
| 312 | void writeFunctionSection(ArrayRef<WasmFunction> Functions); |
| 313 | void writeExportSection(ArrayRef<wasm::WasmExport> Exports); |
| 314 | void writeElemSection(const MCSymbolWasm *IndirectFunctionTable, |
| 315 | ArrayRef<uint32_t> TableElems); |
| 316 | void writeDataCountSection(); |
| 317 | uint32_t writeCodeSection(const MCAssembler &Asm, const MCAsmLayout &Layout, |
| 318 | ArrayRef<WasmFunction> Functions); |
| 319 | uint32_t writeDataSection(const MCAsmLayout &Layout); |
| 320 | void writeTagSection(ArrayRef<wasm::WasmTagType> Tags); |
| 321 | void writeGlobalSection(ArrayRef<wasm::WasmGlobal> Globals); |
| 322 | void writeTableSection(ArrayRef<wasm::WasmTable> Tables); |
| 323 | void writeRelocSection(uint32_t SectionIndex, StringRef Name, |
| 324 | std::vector<WasmRelocationEntry> &Relocations); |
| 325 | void writeLinkingMetaDataSection( |
| 326 | ArrayRef<wasm::WasmSymbolInfo> SymbolInfos, |
| 327 | ArrayRef<std::pair<uint16_t, uint32_t>> InitFuncs, |
| 328 | const std::map<StringRef, std::vector<WasmComdatEntry>> &Comdats); |
| 329 | void writeCustomSection(WasmCustomSection &CustomSection, |
| 330 | const MCAssembler &Asm, const MCAsmLayout &Layout); |
| 331 | void writeCustomRelocSections(); |
| 332 | |
| 333 | uint64_t getProvisionalValue(const WasmRelocationEntry &RelEntry, |
| 334 | const MCAsmLayout &Layout); |
| 335 | void applyRelocations(ArrayRef<WasmRelocationEntry> Relocations, |
| 336 | uint64_t ContentsOffset, const MCAsmLayout &Layout); |
| 337 | |
| 338 | uint32_t getRelocationIndexValue(const WasmRelocationEntry &RelEntry); |
| 339 | uint32_t getFunctionType(const MCSymbolWasm &Symbol); |
| 340 | uint32_t getTagType(const MCSymbolWasm &Symbol); |
| 341 | void registerFunctionType(const MCSymbolWasm &Symbol); |
| 342 | void registerTagType(const MCSymbolWasm &Symbol); |
| 343 | }; |
| 344 | |
| 345 | } // end anonymous namespace |
| 346 | |
| 347 | // Write out a section header and a patchable section size field. |
| 348 | void WasmObjectWriter::startSection(SectionBookkeeping &Section, |
| 349 | unsigned SectionId) { |
| 350 | LLVM_DEBUG(dbgs() << "startSection " << SectionId << "\n")do { } while (false); |
| 351 | W->OS << char(SectionId); |
| 352 | |
| 353 | Section.SizeOffset = W->OS.tell(); |
| 354 | |
| 355 | // The section size. We don't know the size yet, so reserve enough space |
| 356 | // for any 32-bit value; we'll patch it later. |
| 357 | encodeULEB128(0, W->OS, 5); |
| 358 | |
| 359 | // The position where the section starts, for measuring its size. |
| 360 | Section.ContentsOffset = W->OS.tell(); |
| 361 | Section.PayloadOffset = W->OS.tell(); |
| 362 | Section.Index = SectionCount++; |
| 363 | } |
| 364 | |
| 365 | void WasmObjectWriter::startCustomSection(SectionBookkeeping &Section, |
| 366 | StringRef Name) { |
| 367 | LLVM_DEBUG(dbgs() << "startCustomSection " << Name << "\n")do { } while (false); |
| 368 | startSection(Section, wasm::WASM_SEC_CUSTOM); |
| 369 | |
| 370 | // The position where the section header ends, for measuring its size. |
| 371 | Section.PayloadOffset = W->OS.tell(); |
| 372 | |
| 373 | // Custom sections in wasm also have a string identifier. |
| 374 | writeString(Name); |
| 375 | |
| 376 | // The position where the custom section starts. |
| 377 | Section.ContentsOffset = W->OS.tell(); |
| 378 | } |
| 379 | |
| 380 | // Now that the section is complete and we know how big it is, patch up the |
| 381 | // section size field at the start of the section. |
| 382 | void WasmObjectWriter::endSection(SectionBookkeeping &Section) { |
| 383 | uint64_t Size = W->OS.tell(); |
| 384 | // /dev/null doesn't support seek/tell and can report offset of 0. |
| 385 | // Simply skip this patching in that case. |
| 386 | if (!Size) |
| 387 | return; |
| 388 | |
| 389 | Size -= Section.PayloadOffset; |
| 390 | if (uint32_t(Size) != Size) |
| 391 | report_fatal_error("section size does not fit in a uint32_t"); |
| 392 | |
| 393 | LLVM_DEBUG(dbgs() << "endSection size=" << Size << "\n")do { } while (false); |
| 394 | |
| 395 | // Write the final section size to the payload_len field, which follows |
| 396 | // the section id byte. |
| 397 | writePatchableLEB<5>(static_cast<raw_pwrite_stream &>(W->OS), Size, |
| 398 | Section.SizeOffset); |
| 399 | } |
| 400 | |
| 401 | // Emit the Wasm header. |
| 402 | void WasmObjectWriter::writeHeader(const MCAssembler &Asm) { |
| 403 | W->OS.write(wasm::WasmMagic, sizeof(wasm::WasmMagic)); |
| 404 | W->write<uint32_t>(wasm::WasmVersion); |
| 405 | } |
| 406 | |
| 407 | void WasmObjectWriter::executePostLayoutBinding(MCAssembler &Asm, |
| 408 | const MCAsmLayout &Layout) { |
| 409 | // Some compilation units require the indirect function table to be present |
| 410 | // but don't explicitly reference it. This is the case for call_indirect |
| 411 | // without the reference-types feature, and also function bitcasts in all |
| 412 | // cases. In those cases the __indirect_function_table has the |
| 413 | // WASM_SYMBOL_NO_STRIP attribute. Here we make sure this symbol makes it to |
| 414 | // the assembler, if needed. |
| 415 | if (auto *Sym = Asm.getContext().lookupSymbol("__indirect_function_table")) { |
| 416 | const auto *WasmSym = static_cast<const MCSymbolWasm *>(Sym); |
| 417 | if (WasmSym->isNoStrip()) |
| 418 | Asm.registerSymbol(*Sym); |
| 419 | } |
| 420 | |
| 421 | // Build a map of sections to the function that defines them, for use |
| 422 | // in recordRelocation. |
| 423 | for (const MCSymbol &S : Asm.symbols()) { |
| 424 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
| 425 | if (WS.isDefined() && WS.isFunction() && !WS.isVariable()) { |
| 426 | const auto &Sec = static_cast<const MCSectionWasm &>(S.getSection()); |
| 427 | auto Pair = SectionFunctions.insert(std::make_pair(&Sec, &S)); |
| 428 | if (!Pair.second) |
| 429 | report_fatal_error("section already has a defining function: " + |
| 430 | Sec.getName()); |
| 431 | } |
| 432 | } |
| 433 | } |
| 434 | |
| 435 | void WasmObjectWriter::recordRelocation(MCAssembler &Asm, |
| 436 | const MCAsmLayout &Layout, |
| 437 | const MCFragment *Fragment, |
| 438 | const MCFixup &Fixup, MCValue Target, |
| 439 | uint64_t &FixedValue) { |
| 440 | // The WebAssembly backend should never generate FKF_IsPCRel fixups |
| 441 | assert(!(Asm.getBackend().getFixupKindInfo(Fixup.getKind()).Flags &(static_cast<void> (0)) |
| 442 | MCFixupKindInfo::FKF_IsPCRel))(static_cast<void> (0)); |
| 443 | |
| 444 | const auto &FixupSection = cast<MCSectionWasm>(*Fragment->getParent()); |
| 445 | uint64_t C = Target.getConstant(); |
| 446 | uint64_t FixupOffset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset(); |
| 447 | MCContext &Ctx = Asm.getContext(); |
| 448 | bool IsLocRel = false; |
| 449 | |
| 450 | if (const MCSymbolRefExpr *RefB = Target.getSymB()) { |
| 451 | |
| 452 | const auto &SymB = cast<MCSymbolWasm>(RefB->getSymbol()); |
| 453 | |
| 454 | if (FixupSection.getKind().isText()) { |
| 455 | Ctx.reportError(Fixup.getLoc(), |
| 456 | Twine("symbol '") + SymB.getName() + |
| 457 | "' unsupported subtraction expression used in " |
| 458 | "relocation in code section."); |
| 459 | return; |
| 460 | } |
| 461 | |
| 462 | if (SymB.isUndefined()) { |
| 463 | Ctx.reportError(Fixup.getLoc(), |
| 464 | Twine("symbol '") + SymB.getName() + |
| 465 | "' can not be undefined in a subtraction expression"); |
| 466 | return; |
| 467 | } |
| 468 | const MCSection &SecB = SymB.getSection(); |
| 469 | if (&SecB != &FixupSection) { |
| 470 | Ctx.reportError(Fixup.getLoc(), |
| 471 | Twine("symbol '") + SymB.getName() + |
| 472 | "' can not be placed in a different section"); |
| 473 | return; |
| 474 | } |
| 475 | IsLocRel = true; |
| 476 | C += FixupOffset - Layout.getSymbolOffset(SymB); |
| 477 | } |
| 478 | |
| 479 | // We either rejected the fixup or folded B into C at this point. |
| 480 | const MCSymbolRefExpr *RefA = Target.getSymA(); |
| 481 | const auto *SymA = cast<MCSymbolWasm>(&RefA->getSymbol()); |
| 482 | |
| 483 | // The .init_array isn't translated as data, so don't do relocations in it. |
| 484 | if (FixupSection.getName().startswith(".init_array")) { |
| 485 | SymA->setUsedInInitArray(); |
| 486 | return; |
| 487 | } |
| 488 | |
| 489 | if (SymA->isVariable()) { |
| 490 | const MCExpr *Expr = SymA->getVariableValue(); |
| 491 | if (const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr)) |
| 492 | if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF) |
| 493 | llvm_unreachable("weakref used in reloc not yet implemented")__builtin_unreachable(); |
| 494 | } |
| 495 | |
| 496 | // Put any constant offset in an addend. Offsets can be negative, and |
| 497 | // LLVM expects wrapping, in contrast to wasm's immediates which can't |
| 498 | // be negative and don't wrap. |
| 499 | FixedValue = 0; |
| 500 | |
| 501 | unsigned Type = |
| 502 | TargetObjectWriter->getRelocType(Target, Fixup, FixupSection, IsLocRel); |
| 503 | |
| 504 | // Absolute offset within a section or a function. |
| 505 | // Currently only supported for for metadata sections. |
| 506 | // See: test/MC/WebAssembly/blockaddress.ll |
| 507 | if ((Type == wasm::R_WASM_FUNCTION_OFFSET_I32 || |
| 508 | Type == wasm::R_WASM_FUNCTION_OFFSET_I64 || |
| 509 | Type == wasm::R_WASM_SECTION_OFFSET_I32) && |
| 510 | SymA->isDefined()) { |
| 511 | // SymA can be a temp data symbol that represents a function (in which case |
| 512 | // it needs to be replaced by the section symbol), [XXX and it apparently |
| 513 | // later gets changed again to a func symbol?] or it can be a real |
| 514 | // function symbol, in which case it can be left as-is. |
| 515 | |
| 516 | if (!FixupSection.getKind().isMetadata()) |
| 517 | report_fatal_error("relocations for function or section offsets are " |
| 518 | "only supported in metadata sections"); |
| 519 | |
| 520 | const MCSymbol *SectionSymbol = nullptr; |
| 521 | const MCSection &SecA = SymA->getSection(); |
| 522 | if (SecA.getKind().isText()) { |
| 523 | auto SecSymIt = SectionFunctions.find(&SecA); |
| 524 | if (SecSymIt == SectionFunctions.end()) |
| 525 | report_fatal_error("section doesn\'t have defining symbol"); |
| 526 | SectionSymbol = SecSymIt->second; |
| 527 | } else { |
| 528 | SectionSymbol = SecA.getBeginSymbol(); |
| 529 | } |
| 530 | if (!SectionSymbol) |
| 531 | report_fatal_error("section symbol is required for relocation"); |
| 532 | |
| 533 | C += Layout.getSymbolOffset(*SymA); |
| 534 | SymA = cast<MCSymbolWasm>(SectionSymbol); |
| 535 | } |
| 536 | |
| 537 | if (Type == wasm::R_WASM_TABLE_INDEX_REL_SLEB || |
| 538 | Type == wasm::R_WASM_TABLE_INDEX_REL_SLEB64 || |
| 539 | Type == wasm::R_WASM_TABLE_INDEX_SLEB || |
| 540 | Type == wasm::R_WASM_TABLE_INDEX_SLEB64 || |
| 541 | Type == wasm::R_WASM_TABLE_INDEX_I32 || |
| 542 | Type == wasm::R_WASM_TABLE_INDEX_I64) { |
| 543 | // TABLE_INDEX relocs implicitly use the default indirect function table. |
| 544 | // We require the function table to have already been defined. |
| 545 | auto TableName = "__indirect_function_table"; |
| 546 | MCSymbolWasm *Sym = cast_or_null<MCSymbolWasm>(Ctx.lookupSymbol(TableName)); |
| 547 | if (!Sym) { |
| 548 | report_fatal_error("missing indirect function table symbol"); |
| 549 | } else { |
| 550 | if (!Sym->isFunctionTable()) |
| 551 | report_fatal_error("__indirect_function_table symbol has wrong type"); |
| 552 | // Ensure that __indirect_function_table reaches the output. |
| 553 | Sym->setNoStrip(); |
| 554 | Asm.registerSymbol(*Sym); |
| 555 | } |
| 556 | } |
| 557 | |
| 558 | // Relocation other than R_WASM_TYPE_INDEX_LEB are required to be |
| 559 | // against a named symbol. |
| 560 | if (Type != wasm::R_WASM_TYPE_INDEX_LEB) { |
| 561 | if (SymA->getName().empty()) |
| 562 | report_fatal_error("relocations against un-named temporaries are not yet " |
| 563 | "supported by wasm"); |
| 564 | |
| 565 | SymA->setUsedInReloc(); |
| 566 | } |
| 567 | |
| 568 | if (RefA->getKind() == MCSymbolRefExpr::VK_GOT) |
| 569 | SymA->setUsedInGOT(); |
| 570 | |
| 571 | WasmRelocationEntry Rec(FixupOffset, SymA, C, Type, &FixupSection); |
| 572 | LLVM_DEBUG(dbgs() << "WasmReloc: " << Rec << "\n")do { } while (false); |
| 573 | |
| 574 | if (FixupSection.isWasmData()) { |
| 575 | DataRelocations.push_back(Rec); |
| 576 | } else if (FixupSection.getKind().isText()) { |
| 577 | CodeRelocations.push_back(Rec); |
| 578 | } else if (FixupSection.getKind().isMetadata()) { |
| 579 | CustomSectionsRelocations[&FixupSection].push_back(Rec); |
| 580 | } else { |
| 581 | llvm_unreachable("unexpected section type")__builtin_unreachable(); |
| 582 | } |
| 583 | } |
| 584 | |
| 585 | // Compute a value to write into the code at the location covered |
| 586 | // by RelEntry. This value isn't used by the static linker; it just serves |
| 587 | // to make the object format more readable and more likely to be directly |
| 588 | // useable. |
| 589 | uint64_t |
| 590 | WasmObjectWriter::getProvisionalValue(const WasmRelocationEntry &RelEntry, |
| 591 | const MCAsmLayout &Layout) { |
| 592 | if ((RelEntry.Type == wasm::R_WASM_GLOBAL_INDEX_LEB || |
| 593 | RelEntry.Type == wasm::R_WASM_GLOBAL_INDEX_I32) && |
| 594 | !RelEntry.Symbol->isGlobal()) { |
| 595 | assert(GOTIndices.count(RelEntry.Symbol) > 0 && "symbol not found in GOT index space")(static_cast<void> (0)); |
| 596 | return GOTIndices[RelEntry.Symbol]; |
| 597 | } |
| 598 | |
| 599 | switch (RelEntry.Type) { |
| 600 | case wasm::R_WASM_TABLE_INDEX_REL_SLEB: |
| 601 | case wasm::R_WASM_TABLE_INDEX_REL_SLEB64: |
| 602 | case wasm::R_WASM_TABLE_INDEX_SLEB: |
| 603 | case wasm::R_WASM_TABLE_INDEX_SLEB64: |
| 604 | case wasm::R_WASM_TABLE_INDEX_I32: |
| 605 | case wasm::R_WASM_TABLE_INDEX_I64: { |
| 606 | // Provisional value is table address of the resolved symbol itself |
| 607 | const MCSymbolWasm *Base = |
| 608 | cast<MCSymbolWasm>(Layout.getBaseSymbol(*RelEntry.Symbol)); |
| 609 | assert(Base->isFunction())(static_cast<void> (0)); |
| 610 | if (RelEntry.Type == wasm::R_WASM_TABLE_INDEX_REL_SLEB || |
| 611 | RelEntry.Type == wasm::R_WASM_TABLE_INDEX_REL_SLEB64) |
| 612 | return TableIndices[Base] - InitialTableOffset; |
| 613 | else |
| 614 | return TableIndices[Base]; |
| 615 | } |
| 616 | case wasm::R_WASM_TYPE_INDEX_LEB: |
| 617 | // Provisional value is same as the index |
| 618 | return getRelocationIndexValue(RelEntry); |
| 619 | case wasm::R_WASM_FUNCTION_INDEX_LEB: |
| 620 | case wasm::R_WASM_GLOBAL_INDEX_LEB: |
| 621 | case wasm::R_WASM_GLOBAL_INDEX_I32: |
| 622 | case wasm::R_WASM_TAG_INDEX_LEB: |
| 623 | case wasm::R_WASM_TABLE_NUMBER_LEB: |
| 624 | // Provisional value is function/global/tag Wasm index |
| 625 | assert(WasmIndices.count(RelEntry.Symbol) > 0 && "symbol not found in wasm index space")(static_cast<void> (0)); |
| 626 | return WasmIndices[RelEntry.Symbol]; |
| 627 | case wasm::R_WASM_FUNCTION_OFFSET_I32: |
| 628 | case wasm::R_WASM_FUNCTION_OFFSET_I64: |
| 629 | case wasm::R_WASM_SECTION_OFFSET_I32: { |
| 630 | if (!RelEntry.Symbol->isDefined()) |
| 631 | return 0; |
| 632 | const auto &Section = |
| 633 | static_cast<const MCSectionWasm &>(RelEntry.Symbol->getSection()); |
| 634 | return Section.getSectionOffset() + RelEntry.Addend; |
| 635 | } |
| 636 | case wasm::R_WASM_MEMORY_ADDR_LEB: |
| 637 | case wasm::R_WASM_MEMORY_ADDR_LEB64: |
| 638 | case wasm::R_WASM_MEMORY_ADDR_SLEB: |
| 639 | case wasm::R_WASM_MEMORY_ADDR_SLEB64: |
| 640 | case wasm::R_WASM_MEMORY_ADDR_REL_SLEB: |
| 641 | case wasm::R_WASM_MEMORY_ADDR_REL_SLEB64: |
| 642 | case wasm::R_WASM_MEMORY_ADDR_I32: |
| 643 | case wasm::R_WASM_MEMORY_ADDR_I64: |
| 644 | case wasm::R_WASM_MEMORY_ADDR_TLS_SLEB: |
| 645 | case wasm::R_WASM_MEMORY_ADDR_TLS_SLEB64: |
| 646 | case wasm::R_WASM_MEMORY_ADDR_LOCREL_I32: { |
| 647 | // Provisional value is address of the global plus the offset |
| 648 | // For undefined symbols, use zero |
| 649 | if (!RelEntry.Symbol->isDefined()) |
| 650 | return 0; |
| 651 | const wasm::WasmDataReference &SymRef = DataLocations[RelEntry.Symbol]; |
| 652 | const WasmDataSegment &Segment = DataSegments[SymRef.Segment]; |
| 653 | // Ignore overflow. LLVM allows address arithmetic to silently wrap. |
| 654 | return Segment.Offset + SymRef.Offset + RelEntry.Addend; |
| 655 | } |
| 656 | default: |
| 657 | llvm_unreachable("invalid relocation type")__builtin_unreachable(); |
| 658 | } |
| 659 | } |
| 660 | |
| 661 | static void addData(SmallVectorImpl<char> &DataBytes, |
| 662 | MCSectionWasm &DataSection) { |
| 663 | LLVM_DEBUG(errs() << "addData: " << DataSection.getName() << "\n")do { } while (false); |
| 664 | |
| 665 | DataBytes.resize(alignTo(DataBytes.size(), DataSection.getAlignment())); |
| 666 | |
| 667 | for (const MCFragment &Frag : DataSection) { |
| 668 | if (Frag.hasInstructions()) |
| 669 | report_fatal_error("only data supported in data sections"); |
| 670 | |
| 671 | if (auto *Align = dyn_cast<MCAlignFragment>(&Frag)) { |
| 672 | if (Align->getValueSize() != 1) |
| 673 | report_fatal_error("only byte values supported for alignment"); |
| 674 | // If nops are requested, use zeros, as this is the data section. |
| 675 | uint8_t Value = Align->hasEmitNops() ? 0 : Align->getValue(); |
| 676 | uint64_t Size = |
| 677 | std::min<uint64_t>(alignTo(DataBytes.size(), Align->getAlignment()), |
| 678 | DataBytes.size() + Align->getMaxBytesToEmit()); |
| 679 | DataBytes.resize(Size, Value); |
| 680 | } else if (auto *Fill = dyn_cast<MCFillFragment>(&Frag)) { |
| 681 | int64_t NumValues; |
| 682 | if (!Fill->getNumValues().evaluateAsAbsolute(NumValues)) |
| 683 | llvm_unreachable("The fill should be an assembler constant")__builtin_unreachable(); |
| 684 | DataBytes.insert(DataBytes.end(), Fill->getValueSize() * NumValues, |
| 685 | Fill->getValue()); |
| 686 | } else if (auto *LEB = dyn_cast<MCLEBFragment>(&Frag)) { |
| 687 | const SmallVectorImpl<char> &Contents = LEB->getContents(); |
| 688 | llvm::append_range(DataBytes, Contents); |
| 689 | } else { |
| 690 | const auto &DataFrag = cast<MCDataFragment>(Frag); |
| 691 | const SmallVectorImpl<char> &Contents = DataFrag.getContents(); |
| 692 | llvm::append_range(DataBytes, Contents); |
| 693 | } |
| 694 | } |
| 695 | |
| 696 | LLVM_DEBUG(dbgs() << "addData -> " << DataBytes.size() << "\n")do { } while (false); |
| 697 | } |
| 698 | |
| 699 | uint32_t |
| 700 | WasmObjectWriter::getRelocationIndexValue(const WasmRelocationEntry &RelEntry) { |
| 701 | if (RelEntry.Type == wasm::R_WASM_TYPE_INDEX_LEB) { |
| 702 | if (!TypeIndices.count(RelEntry.Symbol)) |
| 703 | report_fatal_error("symbol not found in type index space: " + |
| 704 | RelEntry.Symbol->getName()); |
| 705 | return TypeIndices[RelEntry.Symbol]; |
| 706 | } |
| 707 | |
| 708 | return RelEntry.Symbol->getIndex(); |
| 709 | } |
| 710 | |
| 711 | // Apply the portions of the relocation records that we can handle ourselves |
| 712 | // directly. |
| 713 | void WasmObjectWriter::applyRelocations( |
| 714 | ArrayRef<WasmRelocationEntry> Relocations, uint64_t ContentsOffset, |
| 715 | const MCAsmLayout &Layout) { |
| 716 | auto &Stream = static_cast<raw_pwrite_stream &>(W->OS); |
| 717 | for (const WasmRelocationEntry &RelEntry : Relocations) { |
| 718 | uint64_t Offset = ContentsOffset + |
| 719 | RelEntry.FixupSection->getSectionOffset() + |
| 720 | RelEntry.Offset; |
| 721 | |
| 722 | LLVM_DEBUG(dbgs() << "applyRelocation: " << RelEntry << "\n")do { } while (false); |
| 723 | auto Value = getProvisionalValue(RelEntry, Layout); |
| 724 | |
| 725 | switch (RelEntry.Type) { |
| 726 | case wasm::R_WASM_FUNCTION_INDEX_LEB: |
| 727 | case wasm::R_WASM_TYPE_INDEX_LEB: |
| 728 | case wasm::R_WASM_GLOBAL_INDEX_LEB: |
| 729 | case wasm::R_WASM_MEMORY_ADDR_LEB: |
| 730 | case wasm::R_WASM_TAG_INDEX_LEB: |
| 731 | case wasm::R_WASM_TABLE_NUMBER_LEB: |
| 732 | writePatchableLEB<5>(Stream, Value, Offset); |
| 733 | break; |
| 734 | case wasm::R_WASM_MEMORY_ADDR_LEB64: |
| 735 | writePatchableLEB<10>(Stream, Value, Offset); |
| 736 | break; |
| 737 | case wasm::R_WASM_TABLE_INDEX_I32: |
| 738 | case wasm::R_WASM_MEMORY_ADDR_I32: |
| 739 | case wasm::R_WASM_FUNCTION_OFFSET_I32: |
| 740 | case wasm::R_WASM_SECTION_OFFSET_I32: |
| 741 | case wasm::R_WASM_GLOBAL_INDEX_I32: |
| 742 | case wasm::R_WASM_MEMORY_ADDR_LOCREL_I32: |
| 743 | patchI32(Stream, Value, Offset); |
| 744 | break; |
| 745 | case wasm::R_WASM_TABLE_INDEX_I64: |
| 746 | case wasm::R_WASM_MEMORY_ADDR_I64: |
| 747 | case wasm::R_WASM_FUNCTION_OFFSET_I64: |
| 748 | patchI64(Stream, Value, Offset); |
| 749 | break; |
| 750 | case wasm::R_WASM_TABLE_INDEX_SLEB: |
| 751 | case wasm::R_WASM_TABLE_INDEX_REL_SLEB: |
| 752 | case wasm::R_WASM_MEMORY_ADDR_SLEB: |
| 753 | case wasm::R_WASM_MEMORY_ADDR_REL_SLEB: |
| 754 | case wasm::R_WASM_MEMORY_ADDR_TLS_SLEB: |
| 755 | writePatchableSLEB<5>(Stream, Value, Offset); |
| 756 | break; |
| 757 | case wasm::R_WASM_TABLE_INDEX_SLEB64: |
| 758 | case wasm::R_WASM_TABLE_INDEX_REL_SLEB64: |
| 759 | case wasm::R_WASM_MEMORY_ADDR_SLEB64: |
| 760 | case wasm::R_WASM_MEMORY_ADDR_REL_SLEB64: |
| 761 | case wasm::R_WASM_MEMORY_ADDR_TLS_SLEB64: |
| 762 | writePatchableSLEB<10>(Stream, Value, Offset); |
| 763 | break; |
| 764 | default: |
| 765 | llvm_unreachable("invalid relocation type")__builtin_unreachable(); |
| 766 | } |
| 767 | } |
| 768 | } |
| 769 | |
| 770 | void WasmObjectWriter::writeTypeSection( |
| 771 | ArrayRef<wasm::WasmSignature> Signatures) { |
| 772 | if (Signatures.empty()) |
| 773 | return; |
| 774 | |
| 775 | SectionBookkeeping Section; |
| 776 | startSection(Section, wasm::WASM_SEC_TYPE); |
| 777 | |
| 778 | encodeULEB128(Signatures.size(), W->OS); |
| 779 | |
| 780 | for (const wasm::WasmSignature &Sig : Signatures) { |
| 781 | W->OS << char(wasm::WASM_TYPE_FUNC); |
| 782 | encodeULEB128(Sig.Params.size(), W->OS); |
| 783 | for (wasm::ValType Ty : Sig.Params) |
| 784 | writeValueType(Ty); |
| 785 | encodeULEB128(Sig.Returns.size(), W->OS); |
| 786 | for (wasm::ValType Ty : Sig.Returns) |
| 787 | writeValueType(Ty); |
| 788 | } |
| 789 | |
| 790 | endSection(Section); |
| 791 | } |
| 792 | |
| 793 | void WasmObjectWriter::writeImportSection(ArrayRef<wasm::WasmImport> Imports, |
| 794 | uint64_t DataSize, |
| 795 | uint32_t NumElements) { |
| 796 | if (Imports.empty()) |
| 797 | return; |
| 798 | |
| 799 | uint64_t NumPages = (DataSize + wasm::WasmPageSize - 1) / wasm::WasmPageSize; |
| 800 | |
| 801 | SectionBookkeeping Section; |
| 802 | startSection(Section, wasm::WASM_SEC_IMPORT); |
| 803 | |
| 804 | encodeULEB128(Imports.size(), W->OS); |
| 805 | for (const wasm::WasmImport &Import : Imports) { |
| 806 | writeString(Import.Module); |
| 807 | writeString(Import.Field); |
| 808 | W->OS << char(Import.Kind); |
| 809 | |
| 810 | switch (Import.Kind) { |
| 811 | case wasm::WASM_EXTERNAL_FUNCTION: |
| 812 | encodeULEB128(Import.SigIndex, W->OS); |
| 813 | break; |
| 814 | case wasm::WASM_EXTERNAL_GLOBAL: |
| 815 | W->OS << char(Import.Global.Type); |
| 816 | W->OS << char(Import.Global.Mutable ? 1 : 0); |
| 817 | break; |
| 818 | case wasm::WASM_EXTERNAL_MEMORY: |
| 819 | encodeULEB128(Import.Memory.Flags, W->OS); |
| 820 | encodeULEB128(NumPages, W->OS); // initial |
| 821 | break; |
| 822 | case wasm::WASM_EXTERNAL_TABLE: |
| 823 | W->OS << char(Import.Table.ElemType); |
| 824 | encodeULEB128(0, W->OS); // flags |
| 825 | encodeULEB128(NumElements, W->OS); // initial |
| 826 | break; |
| 827 | case wasm::WASM_EXTERNAL_TAG: |
| 828 | W->OS << char(Import.Tag.Attribute); |
| 829 | encodeULEB128(Import.Tag.SigIndex, W->OS); |
| 830 | break; |
| 831 | default: |
| 832 | llvm_unreachable("unsupported import kind")__builtin_unreachable(); |
| 833 | } |
| 834 | } |
| 835 | |
| 836 | endSection(Section); |
| 837 | } |
| 838 | |
| 839 | void WasmObjectWriter::writeFunctionSection(ArrayRef<WasmFunction> Functions) { |
| 840 | if (Functions.empty()) |
| 841 | return; |
| 842 | |
| 843 | SectionBookkeeping Section; |
| 844 | startSection(Section, wasm::WASM_SEC_FUNCTION); |
| 845 | |
| 846 | encodeULEB128(Functions.size(), W->OS); |
| 847 | for (const WasmFunction &Func : Functions) |
| 848 | encodeULEB128(Func.SigIndex, W->OS); |
| 849 | |
| 850 | endSection(Section); |
| 851 | } |
| 852 | |
| 853 | void WasmObjectWriter::writeTagSection(ArrayRef<wasm::WasmTagType> Tags) { |
| 854 | if (Tags.empty()) |
| 855 | return; |
| 856 | |
| 857 | SectionBookkeeping Section; |
| 858 | startSection(Section, wasm::WASM_SEC_TAG); |
| 859 | |
| 860 | encodeULEB128(Tags.size(), W->OS); |
| 861 | for (const wasm::WasmTagType &Tag : Tags) { |
| 862 | W->OS << char(Tag.Attribute); |
| 863 | encodeULEB128(Tag.SigIndex, W->OS); |
| 864 | } |
| 865 | |
| 866 | endSection(Section); |
| 867 | } |
| 868 | |
| 869 | void WasmObjectWriter::writeGlobalSection(ArrayRef<wasm::WasmGlobal> Globals) { |
| 870 | if (Globals.empty()) |
| 871 | return; |
| 872 | |
| 873 | SectionBookkeeping Section; |
| 874 | startSection(Section, wasm::WASM_SEC_GLOBAL); |
| 875 | |
| 876 | encodeULEB128(Globals.size(), W->OS); |
| 877 | for (const wasm::WasmGlobal &Global : Globals) { |
| 878 | encodeULEB128(Global.Type.Type, W->OS); |
| 879 | W->OS << char(Global.Type.Mutable); |
| 880 | W->OS << char(Global.InitExpr.Opcode); |
| 881 | switch (Global.Type.Type) { |
| 882 | case wasm::WASM_TYPE_I32: |
| 883 | encodeSLEB128(0, W->OS); |
| 884 | break; |
| 885 | case wasm::WASM_TYPE_I64: |
| 886 | encodeSLEB128(0, W->OS); |
| 887 | break; |
| 888 | case wasm::WASM_TYPE_F32: |
| 889 | writeI32(0); |
| 890 | break; |
| 891 | case wasm::WASM_TYPE_F64: |
| 892 | writeI64(0); |
| 893 | break; |
| 894 | case wasm::WASM_TYPE_EXTERNREF: |
| 895 | writeValueType(wasm::ValType::EXTERNREF); |
| 896 | break; |
| 897 | default: |
| 898 | llvm_unreachable("unexpected type")__builtin_unreachable(); |
| 899 | } |
| 900 | W->OS << char(wasm::WASM_OPCODE_END); |
| 901 | } |
| 902 | |
| 903 | endSection(Section); |
| 904 | } |
| 905 | |
| 906 | void WasmObjectWriter::writeTableSection(ArrayRef<wasm::WasmTable> Tables) { |
| 907 | if (Tables.empty()) |
| 908 | return; |
| 909 | |
| 910 | SectionBookkeeping Section; |
| 911 | startSection(Section, wasm::WASM_SEC_TABLE); |
| 912 | |
| 913 | encodeULEB128(Tables.size(), W->OS); |
| 914 | for (const wasm::WasmTable &Table : Tables) { |
| 915 | encodeULEB128(Table.Type.ElemType, W->OS); |
| 916 | encodeULEB128(Table.Type.Limits.Flags, W->OS); |
| 917 | encodeULEB128(Table.Type.Limits.Minimum, W->OS); |
| 918 | if (Table.Type.Limits.Flags & wasm::WASM_LIMITS_FLAG_HAS_MAX) |
| 919 | encodeULEB128(Table.Type.Limits.Maximum, W->OS); |
| 920 | } |
| 921 | endSection(Section); |
| 922 | } |
| 923 | |
| 924 | void WasmObjectWriter::writeExportSection(ArrayRef<wasm::WasmExport> Exports) { |
| 925 | if (Exports.empty()) |
| 926 | return; |
| 927 | |
| 928 | SectionBookkeeping Section; |
| 929 | startSection(Section, wasm::WASM_SEC_EXPORT); |
| 930 | |
| 931 | encodeULEB128(Exports.size(), W->OS); |
| 932 | for (const wasm::WasmExport &Export : Exports) { |
| 933 | writeString(Export.Name); |
| 934 | W->OS << char(Export.Kind); |
| 935 | encodeULEB128(Export.Index, W->OS); |
| 936 | } |
| 937 | |
| 938 | endSection(Section); |
| 939 | } |
| 940 | |
| 941 | void WasmObjectWriter::writeElemSection( |
| 942 | const MCSymbolWasm *IndirectFunctionTable, ArrayRef<uint32_t> TableElems) { |
| 943 | if (TableElems.empty()) |
| 944 | return; |
| 945 | |
| 946 | assert(IndirectFunctionTable)(static_cast<void> (0)); |
| 947 | |
| 948 | SectionBookkeeping Section; |
| 949 | startSection(Section, wasm::WASM_SEC_ELEM); |
| 950 | |
| 951 | encodeULEB128(1, W->OS); // number of "segments" |
| 952 | |
| 953 | assert(WasmIndices.count(IndirectFunctionTable))(static_cast<void> (0)); |
| 954 | uint32_t TableNumber = WasmIndices.find(IndirectFunctionTable)->second; |
| 955 | uint32_t Flags = 0; |
| 956 | if (TableNumber) |
| 957 | Flags |= wasm::WASM_ELEM_SEGMENT_HAS_TABLE_NUMBER; |
| 958 | encodeULEB128(Flags, W->OS); |
| 959 | if (Flags & wasm::WASM_ELEM_SEGMENT_HAS_TABLE_NUMBER) |
| 960 | encodeULEB128(TableNumber, W->OS); // the table number |
| 961 | |
| 962 | // init expr for starting offset |
| 963 | W->OS << char(wasm::WASM_OPCODE_I32_CONST); |
| 964 | encodeSLEB128(InitialTableOffset, W->OS); |
| 965 | W->OS << char(wasm::WASM_OPCODE_END); |
| 966 | |
| 967 | if (Flags & wasm::WASM_ELEM_SEGMENT_MASK_HAS_ELEM_KIND) { |
| 968 | // We only write active function table initializers, for which the elem kind |
| 969 | // is specified to be written as 0x00 and interpreted to mean "funcref". |
| 970 | const uint8_t ElemKind = 0; |
| 971 | W->OS << ElemKind; |
| 972 | } |
| 973 | |
| 974 | encodeULEB128(TableElems.size(), W->OS); |
| 975 | for (uint32_t Elem : TableElems) |
| 976 | encodeULEB128(Elem, W->OS); |
| 977 | |
| 978 | endSection(Section); |
| 979 | } |
| 980 | |
| 981 | void WasmObjectWriter::writeDataCountSection() { |
| 982 | if (DataSegments.empty()) |
| 983 | return; |
| 984 | |
| 985 | SectionBookkeeping Section; |
| 986 | startSection(Section, wasm::WASM_SEC_DATACOUNT); |
| 987 | encodeULEB128(DataSegments.size(), W->OS); |
| 988 | endSection(Section); |
| 989 | } |
| 990 | |
| 991 | uint32_t WasmObjectWriter::writeCodeSection(const MCAssembler &Asm, |
| 992 | const MCAsmLayout &Layout, |
| 993 | ArrayRef<WasmFunction> Functions) { |
| 994 | if (Functions.empty()) |
| 995 | return 0; |
| 996 | |
| 997 | SectionBookkeeping Section; |
| 998 | startSection(Section, wasm::WASM_SEC_CODE); |
| 999 | |
| 1000 | encodeULEB128(Functions.size(), W->OS); |
| 1001 | |
| 1002 | for (const WasmFunction &Func : Functions) { |
| 1003 | auto &FuncSection = static_cast<MCSectionWasm &>(Func.Sym->getSection()); |
| 1004 | |
| 1005 | int64_t Size = 0; |
| 1006 | if (!Func.Sym->getSize()->evaluateAsAbsolute(Size, Layout)) |
| 1007 | report_fatal_error(".size expression must be evaluatable"); |
| 1008 | |
| 1009 | encodeULEB128(Size, W->OS); |
| 1010 | FuncSection.setSectionOffset(W->OS.tell() - Section.ContentsOffset); |
| 1011 | Asm.writeSectionData(W->OS, &FuncSection, Layout); |
| 1012 | } |
| 1013 | |
| 1014 | // Apply fixups. |
| 1015 | applyRelocations(CodeRelocations, Section.ContentsOffset, Layout); |
| 1016 | |
| 1017 | endSection(Section); |
| 1018 | return Section.Index; |
| 1019 | } |
| 1020 | |
| 1021 | uint32_t WasmObjectWriter::writeDataSection(const MCAsmLayout &Layout) { |
| 1022 | if (DataSegments.empty()) |
| 1023 | return 0; |
| 1024 | |
| 1025 | SectionBookkeeping Section; |
| 1026 | startSection(Section, wasm::WASM_SEC_DATA); |
| 1027 | |
| 1028 | encodeULEB128(DataSegments.size(), W->OS); // count |
| 1029 | |
| 1030 | for (const WasmDataSegment &Segment : DataSegments) { |
| 1031 | encodeULEB128(Segment.InitFlags, W->OS); // flags |
| 1032 | if (Segment.InitFlags & wasm::WASM_DATA_SEGMENT_HAS_MEMINDEX) |
| 1033 | encodeULEB128(0, W->OS); // memory index |
| 1034 | if ((Segment.InitFlags & wasm::WASM_DATA_SEGMENT_IS_PASSIVE) == 0) { |
| 1035 | W->OS << char(is64Bit() ? wasm::WASM_OPCODE_I64_CONST |
| 1036 | : wasm::WASM_OPCODE_I32_CONST); |
| 1037 | encodeSLEB128(Segment.Offset, W->OS); // offset |
| 1038 | W->OS << char(wasm::WASM_OPCODE_END); |
| 1039 | } |
| 1040 | encodeULEB128(Segment.Data.size(), W->OS); // size |
| 1041 | Segment.Section->setSectionOffset(W->OS.tell() - Section.ContentsOffset); |
| 1042 | W->OS << Segment.Data; // data |
| 1043 | } |
| 1044 | |
| 1045 | // Apply fixups. |
| 1046 | applyRelocations(DataRelocations, Section.ContentsOffset, Layout); |
| 1047 | |
| 1048 | endSection(Section); |
| 1049 | return Section.Index; |
| 1050 | } |
| 1051 | |
| 1052 | void WasmObjectWriter::writeRelocSection( |
| 1053 | uint32_t SectionIndex, StringRef Name, |
| 1054 | std::vector<WasmRelocationEntry> &Relocs) { |
| 1055 | // See: https://github.com/WebAssembly/tool-conventions/blob/master/Linking.md |
| 1056 | // for descriptions of the reloc sections. |
| 1057 | |
| 1058 | if (Relocs.empty()) |
| 1059 | return; |
| 1060 | |
| 1061 | // First, ensure the relocations are sorted in offset order. In general they |
| 1062 | // should already be sorted since `recordRelocation` is called in offset |
| 1063 | // order, but for the code section we combine many MC sections into single |
| 1064 | // wasm section, and this order is determined by the order of Asm.Symbols() |
| 1065 | // not the sections order. |
| 1066 | llvm::stable_sort( |
| 1067 | Relocs, [](const WasmRelocationEntry &A, const WasmRelocationEntry &B) { |
| 1068 | return (A.Offset + A.FixupSection->getSectionOffset()) < |
| 1069 | (B.Offset + B.FixupSection->getSectionOffset()); |
| 1070 | }); |
| 1071 | |
| 1072 | SectionBookkeeping Section; |
| 1073 | startCustomSection(Section, std::string("reloc.") + Name.str()); |
| 1074 | |
| 1075 | encodeULEB128(SectionIndex, W->OS); |
| 1076 | encodeULEB128(Relocs.size(), W->OS); |
| 1077 | for (const WasmRelocationEntry &RelEntry : Relocs) { |
| 1078 | uint64_t Offset = |
| 1079 | RelEntry.Offset + RelEntry.FixupSection->getSectionOffset(); |
| 1080 | uint32_t Index = getRelocationIndexValue(RelEntry); |
| 1081 | |
| 1082 | W->OS << char(RelEntry.Type); |
| 1083 | encodeULEB128(Offset, W->OS); |
| 1084 | encodeULEB128(Index, W->OS); |
| 1085 | if (RelEntry.hasAddend()) |
| 1086 | encodeSLEB128(RelEntry.Addend, W->OS); |
| 1087 | } |
| 1088 | |
| 1089 | endSection(Section); |
| 1090 | } |
| 1091 | |
| 1092 | void WasmObjectWriter::writeCustomRelocSections() { |
| 1093 | for (const auto &Sec : CustomSections) { |
| 1094 | auto &Relocations = CustomSectionsRelocations[Sec.Section]; |
| 1095 | writeRelocSection(Sec.OutputIndex, Sec.Name, Relocations); |
| 1096 | } |
| 1097 | } |
| 1098 | |
| 1099 | void WasmObjectWriter::writeLinkingMetaDataSection( |
| 1100 | ArrayRef<wasm::WasmSymbolInfo> SymbolInfos, |
| 1101 | ArrayRef<std::pair<uint16_t, uint32_t>> InitFuncs, |
| 1102 | const std::map<StringRef, std::vector<WasmComdatEntry>> &Comdats) { |
| 1103 | SectionBookkeeping Section; |
| 1104 | startCustomSection(Section, "linking"); |
| 1105 | encodeULEB128(wasm::WasmMetadataVersion, W->OS); |
| 1106 | |
| 1107 | SectionBookkeeping SubSection; |
| 1108 | if (SymbolInfos.size() != 0) { |
| 1109 | startSection(SubSection, wasm::WASM_SYMBOL_TABLE); |
| 1110 | encodeULEB128(SymbolInfos.size(), W->OS); |
| 1111 | for (const wasm::WasmSymbolInfo &Sym : SymbolInfos) { |
| 1112 | encodeULEB128(Sym.Kind, W->OS); |
| 1113 | encodeULEB128(Sym.Flags, W->OS); |
| 1114 | switch (Sym.Kind) { |
| 1115 | case wasm::WASM_SYMBOL_TYPE_FUNCTION: |
| 1116 | case wasm::WASM_SYMBOL_TYPE_GLOBAL: |
| 1117 | case wasm::WASM_SYMBOL_TYPE_TAG: |
| 1118 | case wasm::WASM_SYMBOL_TYPE_TABLE: |
| 1119 | encodeULEB128(Sym.ElementIndex, W->OS); |
| 1120 | if ((Sym.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0 || |
| 1121 | (Sym.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) |
| 1122 | writeString(Sym.Name); |
| 1123 | break; |
| 1124 | case wasm::WASM_SYMBOL_TYPE_DATA: |
| 1125 | writeString(Sym.Name); |
| 1126 | if ((Sym.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0) { |
| 1127 | encodeULEB128(Sym.DataRef.Segment, W->OS); |
| 1128 | encodeULEB128(Sym.DataRef.Offset, W->OS); |
| 1129 | encodeULEB128(Sym.DataRef.Size, W->OS); |
| 1130 | } |
| 1131 | break; |
| 1132 | case wasm::WASM_SYMBOL_TYPE_SECTION: { |
| 1133 | const uint32_t SectionIndex = |
| 1134 | CustomSections[Sym.ElementIndex].OutputIndex; |
| 1135 | encodeULEB128(SectionIndex, W->OS); |
| 1136 | break; |
| 1137 | } |
| 1138 | default: |
| 1139 | llvm_unreachable("unexpected kind")__builtin_unreachable(); |
| 1140 | } |
| 1141 | } |
| 1142 | endSection(SubSection); |
| 1143 | } |
| 1144 | |
| 1145 | if (DataSegments.size()) { |
| 1146 | startSection(SubSection, wasm::WASM_SEGMENT_INFO); |
| 1147 | encodeULEB128(DataSegments.size(), W->OS); |
| 1148 | for (const WasmDataSegment &Segment : DataSegments) { |
| 1149 | writeString(Segment.Name); |
| 1150 | encodeULEB128(Segment.Alignment, W->OS); |
| 1151 | encodeULEB128(Segment.LinkingFlags, W->OS); |
| 1152 | } |
| 1153 | endSection(SubSection); |
| 1154 | } |
| 1155 | |
| 1156 | if (!InitFuncs.empty()) { |
| 1157 | startSection(SubSection, wasm::WASM_INIT_FUNCS); |
| 1158 | encodeULEB128(InitFuncs.size(), W->OS); |
| 1159 | for (auto &StartFunc : InitFuncs) { |
| 1160 | encodeULEB128(StartFunc.first, W->OS); // priority |
| 1161 | encodeULEB128(StartFunc.second, W->OS); // function index |
| 1162 | } |
| 1163 | endSection(SubSection); |
| 1164 | } |
| 1165 | |
| 1166 | if (Comdats.size()) { |
| 1167 | startSection(SubSection, wasm::WASM_COMDAT_INFO); |
| 1168 | encodeULEB128(Comdats.size(), W->OS); |
| 1169 | for (const auto &C : Comdats) { |
| 1170 | writeString(C.first); |
| 1171 | encodeULEB128(0, W->OS); // flags for future use |
| 1172 | encodeULEB128(C.second.size(), W->OS); |
| 1173 | for (const WasmComdatEntry &Entry : C.second) { |
| 1174 | encodeULEB128(Entry.Kind, W->OS); |
| 1175 | encodeULEB128(Entry.Index, W->OS); |
| 1176 | } |
| 1177 | } |
| 1178 | endSection(SubSection); |
| 1179 | } |
| 1180 | |
| 1181 | endSection(Section); |
| 1182 | } |
| 1183 | |
| 1184 | void WasmObjectWriter::writeCustomSection(WasmCustomSection &CustomSection, |
| 1185 | const MCAssembler &Asm, |
| 1186 | const MCAsmLayout &Layout) { |
| 1187 | SectionBookkeeping Section; |
| 1188 | auto *Sec = CustomSection.Section; |
| 1189 | startCustomSection(Section, CustomSection.Name); |
| 1190 | |
| 1191 | Sec->setSectionOffset(W->OS.tell() - Section.ContentsOffset); |
| 1192 | Asm.writeSectionData(W->OS, Sec, Layout); |
| 1193 | |
| 1194 | CustomSection.OutputContentsOffset = Section.ContentsOffset; |
| 1195 | CustomSection.OutputIndex = Section.Index; |
| 1196 | |
| 1197 | endSection(Section); |
| 1198 | |
| 1199 | // Apply fixups. |
| 1200 | auto &Relocations = CustomSectionsRelocations[CustomSection.Section]; |
| 1201 | applyRelocations(Relocations, CustomSection.OutputContentsOffset, Layout); |
| 1202 | } |
| 1203 | |
| 1204 | uint32_t WasmObjectWriter::getFunctionType(const MCSymbolWasm &Symbol) { |
| 1205 | assert(Symbol.isFunction())(static_cast<void> (0)); |
| 1206 | assert(TypeIndices.count(&Symbol))(static_cast<void> (0)); |
| 1207 | return TypeIndices[&Symbol]; |
| 1208 | } |
| 1209 | |
| 1210 | uint32_t WasmObjectWriter::getTagType(const MCSymbolWasm &Symbol) { |
| 1211 | assert(Symbol.isTag())(static_cast<void> (0)); |
| 1212 | assert(TypeIndices.count(&Symbol))(static_cast<void> (0)); |
| 1213 | return TypeIndices[&Symbol]; |
| 1214 | } |
| 1215 | |
| 1216 | void WasmObjectWriter::registerFunctionType(const MCSymbolWasm &Symbol) { |
| 1217 | assert(Symbol.isFunction())(static_cast<void> (0)); |
| 1218 | |
| 1219 | wasm::WasmSignature S; |
| 1220 | |
| 1221 | if (auto *Sig = Symbol.getSignature()) { |
| 1222 | S.Returns = Sig->Returns; |
| 1223 | S.Params = Sig->Params; |
| 1224 | } |
| 1225 | |
| 1226 | auto Pair = SignatureIndices.insert(std::make_pair(S, Signatures.size())); |
| 1227 | if (Pair.second) |
| 1228 | Signatures.push_back(S); |
| 1229 | TypeIndices[&Symbol] = Pair.first->second; |
| 1230 | |
| 1231 | LLVM_DEBUG(dbgs() << "registerFunctionType: " << Symboldo { } while (false) |
| 1232 | << " new:" << Pair.second << "\n")do { } while (false); |
| 1233 | LLVM_DEBUG(dbgs() << " -> type index: " << Pair.first->second << "\n")do { } while (false); |
| 1234 | } |
| 1235 | |
| 1236 | void WasmObjectWriter::registerTagType(const MCSymbolWasm &Symbol) { |
| 1237 | assert(Symbol.isTag())(static_cast<void> (0)); |
| 1238 | |
| 1239 | // TODO Currently we don't generate imported exceptions, but if we do, we |
| 1240 | // should have a way of infering types of imported exceptions. |
| 1241 | wasm::WasmSignature S; |
| 1242 | if (auto *Sig = Symbol.getSignature()) { |
| 1243 | S.Returns = Sig->Returns; |
| 1244 | S.Params = Sig->Params; |
| 1245 | } |
| 1246 | |
| 1247 | auto Pair = SignatureIndices.insert(std::make_pair(S, Signatures.size())); |
| 1248 | if (Pair.second) |
| 1249 | Signatures.push_back(S); |
| 1250 | TypeIndices[&Symbol] = Pair.first->second; |
| 1251 | |
| 1252 | LLVM_DEBUG(dbgs() << "registerTagType: " << Symbol << " new:" << Pair.seconddo { } while (false) |
| 1253 | << "\n")do { } while (false); |
| 1254 | LLVM_DEBUG(dbgs() << " -> type index: " << Pair.first->second << "\n")do { } while (false); |
| 1255 | } |
| 1256 | |
| 1257 | static bool isInSymtab(const MCSymbolWasm &Sym) { |
| 1258 | if (Sym.isUsedInReloc() || Sym.isUsedInInitArray()) |
| 1259 | return true; |
| 1260 | |
| 1261 | if (Sym.isComdat() && !Sym.isDefined()) |
| 1262 | return false; |
| 1263 | |
| 1264 | if (Sym.isTemporary()) |
| 1265 | return false; |
| 1266 | |
| 1267 | if (Sym.isSection()) |
| 1268 | return false; |
| 1269 | |
| 1270 | if (Sym.omitFromLinkingSection()) |
| 1271 | return false; |
| 1272 | |
| 1273 | return true; |
| 1274 | } |
| 1275 | |
| 1276 | void WasmObjectWriter::prepareImports( |
| 1277 | SmallVectorImpl<wasm::WasmImport> &Imports, MCAssembler &Asm, |
| 1278 | const MCAsmLayout &Layout) { |
| 1279 | // For now, always emit the memory import, since loads and stores are not |
| 1280 | // valid without it. In the future, we could perhaps be more clever and omit |
| 1281 | // it if there are no loads or stores. |
| 1282 | wasm::WasmImport MemImport; |
| 1283 | MemImport.Module = "env"; |
| 1284 | MemImport.Field = "__linear_memory"; |
| 1285 | MemImport.Kind = wasm::WASM_EXTERNAL_MEMORY; |
| 1286 | MemImport.Memory.Flags = is64Bit() ? wasm::WASM_LIMITS_FLAG_IS_64 |
| 1287 | : wasm::WASM_LIMITS_FLAG_NONE; |
| 1288 | Imports.push_back(MemImport); |
| 1289 | |
| 1290 | // Populate SignatureIndices, and Imports and WasmIndices for undefined |
| 1291 | // symbols. This must be done before populating WasmIndices for defined |
| 1292 | // symbols. |
| 1293 | for (const MCSymbol &S : Asm.symbols()) { |
| 1294 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
| 1295 | |
| 1296 | // Register types for all functions, including those with private linkage |
| 1297 | // (because wasm always needs a type signature). |
| 1298 | if (WS.isFunction()) { |
| 1299 | const auto *BS = Layout.getBaseSymbol(S); |
| 1300 | if (!BS) |
| 1301 | report_fatal_error(Twine(S.getName()) + |
| 1302 | ": absolute addressing not supported!"); |
| 1303 | registerFunctionType(*cast<MCSymbolWasm>(BS)); |
| 1304 | } |
| 1305 | |
| 1306 | if (WS.isTag()) |
| 1307 | registerTagType(WS); |
| 1308 | |
| 1309 | if (WS.isTemporary()) |
| 1310 | continue; |
| 1311 | |
| 1312 | // If the symbol is not defined in this translation unit, import it. |
| 1313 | if (!WS.isDefined() && !WS.isComdat()) { |
| 1314 | if (WS.isFunction()) { |
| 1315 | wasm::WasmImport Import; |
| 1316 | Import.Module = WS.getImportModule(); |
| 1317 | Import.Field = WS.getImportName(); |
| 1318 | Import.Kind = wasm::WASM_EXTERNAL_FUNCTION; |
| 1319 | Import.SigIndex = getFunctionType(WS); |
| 1320 | Imports.push_back(Import); |
| 1321 | assert(WasmIndices.count(&WS) == 0)(static_cast<void> (0)); |
| 1322 | WasmIndices[&WS] = NumFunctionImports++; |
| 1323 | } else if (WS.isGlobal()) { |
| 1324 | if (WS.isWeak()) |
| 1325 | report_fatal_error("undefined global symbol cannot be weak"); |
| 1326 | |
| 1327 | wasm::WasmImport Import; |
| 1328 | Import.Field = WS.getImportName(); |
| 1329 | Import.Kind = wasm::WASM_EXTERNAL_GLOBAL; |
| 1330 | Import.Module = WS.getImportModule(); |
| 1331 | Import.Global = WS.getGlobalType(); |
| 1332 | Imports.push_back(Import); |
| 1333 | assert(WasmIndices.count(&WS) == 0)(static_cast<void> (0)); |
| 1334 | WasmIndices[&WS] = NumGlobalImports++; |
| 1335 | } else if (WS.isTag()) { |
| 1336 | if (WS.isWeak()) |
| 1337 | report_fatal_error("undefined tag symbol cannot be weak"); |
| 1338 | |
| 1339 | wasm::WasmImport Import; |
| 1340 | Import.Module = WS.getImportModule(); |
| 1341 | Import.Field = WS.getImportName(); |
| 1342 | Import.Kind = wasm::WASM_EXTERNAL_TAG; |
| 1343 | Import.Tag.Attribute = wasm::WASM_TAG_ATTRIBUTE_EXCEPTION; |
| 1344 | Import.Tag.SigIndex = getTagType(WS); |
| 1345 | Imports.push_back(Import); |
| 1346 | assert(WasmIndices.count(&WS) == 0)(static_cast<void> (0)); |
| 1347 | WasmIndices[&WS] = NumTagImports++; |
| 1348 | } else if (WS.isTable()) { |
| 1349 | if (WS.isWeak()) |
| 1350 | report_fatal_error("undefined table symbol cannot be weak"); |
| 1351 | |
| 1352 | wasm::WasmImport Import; |
| 1353 | Import.Module = WS.getImportModule(); |
| 1354 | Import.Field = WS.getImportName(); |
| 1355 | Import.Kind = wasm::WASM_EXTERNAL_TABLE; |
| 1356 | Import.Table = WS.getTableType(); |
| 1357 | Imports.push_back(Import); |
| 1358 | assert(WasmIndices.count(&WS) == 0)(static_cast<void> (0)); |
| 1359 | WasmIndices[&WS] = NumTableImports++; |
| 1360 | } |
| 1361 | } |
| 1362 | } |
| 1363 | |
| 1364 | // Add imports for GOT globals |
| 1365 | for (const MCSymbol &S : Asm.symbols()) { |
| 1366 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
| 1367 | if (WS.isUsedInGOT()) { |
| 1368 | wasm::WasmImport Import; |
| 1369 | if (WS.isFunction()) |
| 1370 | Import.Module = "GOT.func"; |
| 1371 | else |
| 1372 | Import.Module = "GOT.mem"; |
| 1373 | Import.Field = WS.getName(); |
| 1374 | Import.Kind = wasm::WASM_EXTERNAL_GLOBAL; |
| 1375 | Import.Global = {wasm::WASM_TYPE_I32, true}; |
| 1376 | Imports.push_back(Import); |
| 1377 | assert(GOTIndices.count(&WS) == 0)(static_cast<void> (0)); |
| 1378 | GOTIndices[&WS] = NumGlobalImports++; |
| 1379 | } |
| 1380 | } |
| 1381 | } |
| 1382 | |
| 1383 | uint64_t WasmObjectWriter::writeObject(MCAssembler &Asm, |
| 1384 | const MCAsmLayout &Layout) { |
| 1385 | support::endian::Writer MainWriter(*OS, support::little); |
| 1386 | W = &MainWriter; |
| 1387 | if (IsSplitDwarf) { |
| 1388 | uint64_t TotalSize = writeOneObject(Asm, Layout, DwoMode::NonDwoOnly); |
| 1389 | assert(DwoOS)(static_cast<void> (0)); |
| 1390 | support::endian::Writer DwoWriter(*DwoOS, support::little); |
| 1391 | W = &DwoWriter; |
| 1392 | return TotalSize + writeOneObject(Asm, Layout, DwoMode::DwoOnly); |
| 1393 | } else { |
| 1394 | return writeOneObject(Asm, Layout, DwoMode::AllSections); |
| 1395 | } |
| 1396 | } |
| 1397 | |
| 1398 | uint64_t WasmObjectWriter::writeOneObject(MCAssembler &Asm, |
| 1399 | const MCAsmLayout &Layout, |
| 1400 | DwoMode Mode) { |
| 1401 | uint64_t StartOffset = W->OS.tell(); |
| 1402 | SectionCount = 0; |
| 1403 | CustomSections.clear(); |
| 1404 | |
| 1405 | LLVM_DEBUG(dbgs() << "WasmObjectWriter::writeObject\n")do { } while (false); |
| 1406 | |
| 1407 | // Collect information from the available symbols. |
| 1408 | SmallVector<WasmFunction, 4> Functions; |
| 1409 | SmallVector<uint32_t, 4> TableElems; |
| 1410 | SmallVector<wasm::WasmImport, 4> Imports; |
| 1411 | SmallVector<wasm::WasmExport, 4> Exports; |
| 1412 | SmallVector<wasm::WasmTagType, 1> Tags; |
| 1413 | SmallVector<wasm::WasmGlobal, 1> Globals; |
| 1414 | SmallVector<wasm::WasmTable, 1> Tables; |
| 1415 | SmallVector<wasm::WasmSymbolInfo, 4> SymbolInfos; |
| 1416 | SmallVector<std::pair<uint16_t, uint32_t>, 2> InitFuncs; |
| 1417 | std::map<StringRef, std::vector<WasmComdatEntry>> Comdats; |
| 1418 | uint64_t DataSize = 0; |
| 1419 | if (Mode != DwoMode::DwoOnly) { |
| 1420 | prepareImports(Imports, Asm, Layout); |
| 1421 | } |
| 1422 | |
| 1423 | // Populate DataSegments and CustomSections, which must be done before |
| 1424 | // populating DataLocations. |
| 1425 | for (MCSection &Sec : Asm) { |
| 1426 | auto &Section = static_cast<MCSectionWasm &>(Sec); |
| 1427 | StringRef SectionName = Section.getName(); |
| 1428 | |
| 1429 | if (Mode == DwoMode::NonDwoOnly && isDwoSection(Sec)) |
| 1430 | continue; |
| 1431 | if (Mode == DwoMode::DwoOnly && !isDwoSection(Sec)) |
| 1432 | continue; |
| 1433 | |
| 1434 | LLVM_DEBUG(dbgs() << "Processing Section " << SectionName << " group "do { } while (false) |
| 1435 | << Section.getGroup() << "\n";)do { } while (false); |
| 1436 | |
| 1437 | // .init_array sections are handled specially elsewhere. |
| 1438 | if (SectionName.startswith(".init_array")) |
| 1439 | continue; |
| 1440 | |
| 1441 | // Code is handled separately |
| 1442 | if (Section.getKind().isText()) |
| 1443 | continue; |
| 1444 | |
| 1445 | if (Section.isWasmData()) { |
| 1446 | uint32_t SegmentIndex = DataSegments.size(); |
| 1447 | DataSize = alignTo(DataSize, Section.getAlignment()); |
| 1448 | DataSegments.emplace_back(); |
| 1449 | WasmDataSegment &Segment = DataSegments.back(); |
| 1450 | Segment.Name = SectionName; |
| 1451 | Segment.InitFlags = Section.getPassive() |
| 1452 | ? (uint32_t)wasm::WASM_DATA_SEGMENT_IS_PASSIVE |
| 1453 | : 0; |
| 1454 | Segment.Offset = DataSize; |
| 1455 | Segment.Section = &Section; |
| 1456 | addData(Segment.Data, Section); |
| 1457 | Segment.Alignment = Log2_32(Section.getAlignment()); |
| 1458 | Segment.LinkingFlags = Section.getSegmentFlags(); |
| 1459 | DataSize += Segment.Data.size(); |
| 1460 | Section.setSegmentIndex(SegmentIndex); |
| 1461 | |
| 1462 | if (const MCSymbolWasm *C = Section.getGroup()) { |
| 1463 | Comdats[C->getName()].emplace_back( |
| 1464 | WasmComdatEntry{wasm::WASM_COMDAT_DATA, SegmentIndex}); |
| 1465 | } |
| 1466 | } else { |
| 1467 | // Create custom sections |
| 1468 | assert(Sec.getKind().isMetadata())(static_cast<void> (0)); |
| 1469 | |
| 1470 | StringRef Name = SectionName; |
| 1471 | |
| 1472 | // For user-defined custom sections, strip the prefix |
| 1473 | if (Name.startswith(".custom_section.")) |
| 1474 | Name = Name.substr(strlen(".custom_section.")); |
| 1475 | |
| 1476 | MCSymbol *Begin = Sec.getBeginSymbol(); |
| 1477 | if (Begin) { |
| 1478 | assert(WasmIndices.count(cast<MCSymbolWasm>(Begin)) == 0)(static_cast<void> (0)); |
| 1479 | WasmIndices[cast<MCSymbolWasm>(Begin)] = CustomSections.size(); |
| 1480 | } |
| 1481 | |
| 1482 | // Separate out the producers and target features sections |
| 1483 | if (Name == "producers") { |
| 1484 | ProducersSection = std::make_unique<WasmCustomSection>(Name, &Section); |
| 1485 | continue; |
| 1486 | } |
| 1487 | if (Name == "target_features") { |
| 1488 | TargetFeaturesSection = |
| 1489 | std::make_unique<WasmCustomSection>(Name, &Section); |
| 1490 | continue; |
| 1491 | } |
| 1492 | |
| 1493 | // Custom sections can also belong to COMDAT groups. In this case the |
| 1494 | // decriptor's "index" field is the section index (in the final object |
| 1495 | // file), but that is not known until after layout, so it must be fixed up |
| 1496 | // later |
| 1497 | if (const MCSymbolWasm *C = Section.getGroup()) { |
| 1498 | Comdats[C->getName()].emplace_back( |
| 1499 | WasmComdatEntry{wasm::WASM_COMDAT_SECTION, |
| 1500 | static_cast<uint32_t>(CustomSections.size())}); |
| 1501 | } |
| 1502 | |
| 1503 | CustomSections.emplace_back(Name, &Section); |
| 1504 | } |
| 1505 | } |
| 1506 | |
| 1507 | if (Mode != DwoMode::DwoOnly) { |
| 1508 | // Populate WasmIndices and DataLocations for defined symbols. |
| 1509 | for (const MCSymbol &S : Asm.symbols()) { |
| 1510 | // Ignore unnamed temporary symbols, which aren't ever exported, imported, |
| 1511 | // or used in relocations. |
| 1512 | if (S.isTemporary() && S.getName().empty()) |
| 1513 | continue; |
| 1514 | |
| 1515 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
| 1516 | LLVM_DEBUG(dbgs()do { } while (false) |
| 1517 | << "MCSymbol: "do { } while (false) |
| 1518 | << toString(WS.getType().getValueOr(wasm::WASM_SYMBOL_TYPE_DATA))do { } while (false) |
| 1519 | << " '" << S << "'"do { } while (false) |
| 1520 | << " isDefined=" << S.isDefined() << " isExternal="do { } while (false) |
| 1521 | << S.isExternal() << " isTemporary=" << S.isTemporary()do { } while (false) |
| 1522 | << " isWeak=" << WS.isWeak() << " isHidden=" << WS.isHidden()do { } while (false) |
| 1523 | << " isVariable=" << WS.isVariable() << "\n")do { } while (false); |
| 1524 | |
| 1525 | if (WS.isVariable()) |
| 1526 | continue; |
| 1527 | if (WS.isComdat() && !WS.isDefined()) |
| 1528 | continue; |
| 1529 | |
| 1530 | if (WS.isFunction()) { |
| 1531 | unsigned Index; |
| 1532 | if (WS.isDefined()) { |
| 1533 | if (WS.getOffset() != 0) |
| 1534 | report_fatal_error( |
| 1535 | "function sections must contain one function each"); |
| 1536 | |
| 1537 | if (WS.getSize() == nullptr) |
| 1538 | report_fatal_error( |
| 1539 | "function symbols must have a size set with .size"); |
| 1540 | |
| 1541 | // A definition. Write out the function body. |
| 1542 | Index = NumFunctionImports + Functions.size(); |
| 1543 | WasmFunction Func; |
| 1544 | Func.SigIndex = getFunctionType(WS); |
| 1545 | Func.Sym = &WS; |
| 1546 | assert(WasmIndices.count(&WS) == 0)(static_cast<void> (0)); |
| 1547 | WasmIndices[&WS] = Index; |
| 1548 | Functions.push_back(Func); |
| 1549 | |
| 1550 | auto &Section = static_cast<MCSectionWasm &>(WS.getSection()); |
| 1551 | if (const MCSymbolWasm *C = Section.getGroup()) { |
| 1552 | Comdats[C->getName()].emplace_back( |
| 1553 | WasmComdatEntry{wasm::WASM_COMDAT_FUNCTION, Index}); |
| 1554 | } |
| 1555 | |
| 1556 | if (WS.hasExportName()) { |
| 1557 | wasm::WasmExport Export; |
| 1558 | Export.Name = WS.getExportName(); |
| 1559 | Export.Kind = wasm::WASM_EXTERNAL_FUNCTION; |
| 1560 | Export.Index = Index; |
| 1561 | Exports.push_back(Export); |
| 1562 | } |
| 1563 | } else { |
| 1564 | // An import; the index was assigned above. |
| 1565 | Index = WasmIndices.find(&WS)->second; |
Value stored to 'Index' is never read | |
| 1566 | } |
| 1567 | |
| 1568 | LLVM_DEBUG(dbgs() << " -> function index: " << Index << "\n")do { } while (false); |
| 1569 | |
| 1570 | } else if (WS.isData()) { |
| 1571 | if (!isInSymtab(WS)) |
| 1572 | continue; |
| 1573 | |
| 1574 | if (!WS.isDefined()) { |
| 1575 | LLVM_DEBUG(dbgs() << " -> segment index: -1"do { } while (false) |
| 1576 | << "\n")do { } while (false); |
| 1577 | continue; |
| 1578 | } |
| 1579 | |
| 1580 | if (!WS.getSize()) |
| 1581 | report_fatal_error("data symbols must have a size set with .size: " + |
| 1582 | WS.getName()); |
| 1583 | |
| 1584 | int64_t Size = 0; |
| 1585 | if (!WS.getSize()->evaluateAsAbsolute(Size, Layout)) |
| 1586 | report_fatal_error(".size expression must be evaluatable"); |
| 1587 | |
| 1588 | auto &DataSection = static_cast<MCSectionWasm &>(WS.getSection()); |
| 1589 | if (!DataSection.isWasmData()) |
| 1590 | report_fatal_error("data symbols must live in a data section: " + |
| 1591 | WS.getName()); |
| 1592 | |
| 1593 | // For each data symbol, export it in the symtab as a reference to the |
| 1594 | // corresponding Wasm data segment. |
| 1595 | wasm::WasmDataReference Ref = wasm::WasmDataReference{ |
| 1596 | DataSection.getSegmentIndex(), Layout.getSymbolOffset(WS), |
| 1597 | static_cast<uint64_t>(Size)}; |
| 1598 | assert(DataLocations.count(&WS) == 0)(static_cast<void> (0)); |
| 1599 | DataLocations[&WS] = Ref; |
| 1600 | LLVM_DEBUG(dbgs() << " -> segment index: " << Ref.Segment << "\n")do { } while (false); |
| 1601 | |
| 1602 | } else if (WS.isGlobal()) { |
| 1603 | // A "true" Wasm global (currently just __stack_pointer) |
| 1604 | if (WS.isDefined()) { |
| 1605 | wasm::WasmGlobal Global; |
| 1606 | Global.Type = WS.getGlobalType(); |
| 1607 | Global.Index = NumGlobalImports + Globals.size(); |
| 1608 | switch (Global.Type.Type) { |
| 1609 | case wasm::WASM_TYPE_I32: |
| 1610 | Global.InitExpr.Opcode = wasm::WASM_OPCODE_I32_CONST; |
| 1611 | break; |
| 1612 | case wasm::WASM_TYPE_I64: |
| 1613 | Global.InitExpr.Opcode = wasm::WASM_OPCODE_I64_CONST; |
| 1614 | break; |
| 1615 | case wasm::WASM_TYPE_F32: |
| 1616 | Global.InitExpr.Opcode = wasm::WASM_OPCODE_F32_CONST; |
| 1617 | break; |
| 1618 | case wasm::WASM_TYPE_F64: |
| 1619 | Global.InitExpr.Opcode = wasm::WASM_OPCODE_F64_CONST; |
| 1620 | break; |
| 1621 | case wasm::WASM_TYPE_EXTERNREF: |
| 1622 | Global.InitExpr.Opcode = wasm::WASM_OPCODE_REF_NULL; |
| 1623 | break; |
| 1624 | default: |
| 1625 | llvm_unreachable("unexpected type")__builtin_unreachable(); |
| 1626 | } |
| 1627 | assert(WasmIndices.count(&WS) == 0)(static_cast<void> (0)); |
| 1628 | WasmIndices[&WS] = Global.Index; |
| 1629 | Globals.push_back(Global); |
| 1630 | } else { |
| 1631 | // An import; the index was assigned above |
| 1632 | LLVM_DEBUG(dbgs() << " -> global index: "do { } while (false) |
| 1633 | << WasmIndices.find(&WS)->second << "\n")do { } while (false); |
| 1634 | } |
| 1635 | } else if (WS.isTable()) { |
| 1636 | if (WS.isDefined()) { |
| 1637 | wasm::WasmTable Table; |
| 1638 | Table.Index = NumTableImports + Tables.size(); |
| 1639 | Table.Type = WS.getTableType(); |
| 1640 | assert(WasmIndices.count(&WS) == 0)(static_cast<void> (0)); |
| 1641 | WasmIndices[&WS] = Table.Index; |
| 1642 | Tables.push_back(Table); |
| 1643 | } |
| 1644 | LLVM_DEBUG(dbgs() << " -> table index: "do { } while (false) |
| 1645 | << WasmIndices.find(&WS)->second << "\n")do { } while (false); |
| 1646 | } else if (WS.isTag()) { |
| 1647 | // C++ exception symbol (__cpp_exception) or longjmp symbol |
| 1648 | // (__c_longjmp) |
| 1649 | unsigned Index; |
| 1650 | if (WS.isDefined()) { |
| 1651 | Index = NumTagImports + Tags.size(); |
| 1652 | wasm::WasmTagType Tag; |
| 1653 | Tag.SigIndex = getTagType(WS); |
| 1654 | Tag.Attribute = wasm::WASM_TAG_ATTRIBUTE_EXCEPTION; |
| 1655 | assert(WasmIndices.count(&WS) == 0)(static_cast<void> (0)); |
| 1656 | WasmIndices[&WS] = Index; |
| 1657 | Tags.push_back(Tag); |
| 1658 | } else { |
| 1659 | // An import; the index was assigned above. |
| 1660 | assert(WasmIndices.count(&WS) > 0)(static_cast<void> (0)); |
| 1661 | } |
| 1662 | LLVM_DEBUG(dbgs() << " -> tag index: " << WasmIndices.find(&WS)->seconddo { } while (false) |
| 1663 | << "\n")do { } while (false); |
| 1664 | |
| 1665 | } else { |
| 1666 | assert(WS.isSection())(static_cast<void> (0)); |
| 1667 | } |
| 1668 | } |
| 1669 | |
| 1670 | // Populate WasmIndices and DataLocations for aliased symbols. We need to |
| 1671 | // process these in a separate pass because we need to have processed the |
| 1672 | // target of the alias before the alias itself and the symbols are not |
| 1673 | // necessarily ordered in this way. |
| 1674 | for (const MCSymbol &S : Asm.symbols()) { |
| 1675 | if (!S.isVariable()) |
| 1676 | continue; |
| 1677 | |
| 1678 | assert(S.isDefined())(static_cast<void> (0)); |
| 1679 | |
| 1680 | const auto *BS = Layout.getBaseSymbol(S); |
| 1681 | if (!BS) |
| 1682 | report_fatal_error(Twine(S.getName()) + |
| 1683 | ": absolute addressing not supported!"); |
| 1684 | const MCSymbolWasm *Base = cast<MCSymbolWasm>(BS); |
| 1685 | |
| 1686 | // Find the target symbol of this weak alias and export that index |
| 1687 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
| 1688 | LLVM_DEBUG(dbgs() << WS.getName() << ": weak alias of '" << *Basedo { } while (false) |
| 1689 | << "'\n")do { } while (false); |
| 1690 | |
| 1691 | if (Base->isFunction()) { |
| 1692 | assert(WasmIndices.count(Base) > 0)(static_cast<void> (0)); |
| 1693 | uint32_t WasmIndex = WasmIndices.find(Base)->second; |
| 1694 | assert(WasmIndices.count(&WS) == 0)(static_cast<void> (0)); |
| 1695 | WasmIndices[&WS] = WasmIndex; |
| 1696 | LLVM_DEBUG(dbgs() << " -> index:" << WasmIndex << "\n")do { } while (false); |
| 1697 | } else if (Base->isData()) { |
| 1698 | auto &DataSection = static_cast<MCSectionWasm &>(WS.getSection()); |
| 1699 | uint64_t Offset = Layout.getSymbolOffset(S); |
| 1700 | int64_t Size = 0; |
| 1701 | // For data symbol alias we use the size of the base symbol as the |
| 1702 | // size of the alias. When an offset from the base is involved this |
| 1703 | // can result in a offset + size goes past the end of the data section |
| 1704 | // which out object format doesn't support. So we must clamp it. |
| 1705 | if (!Base->getSize()->evaluateAsAbsolute(Size, Layout)) |
| 1706 | report_fatal_error(".size expression must be evaluatable"); |
| 1707 | const WasmDataSegment &Segment = |
| 1708 | DataSegments[DataSection.getSegmentIndex()]; |
| 1709 | Size = |
| 1710 | std::min(static_cast<uint64_t>(Size), Segment.Data.size() - Offset); |
| 1711 | wasm::WasmDataReference Ref = wasm::WasmDataReference{ |
| 1712 | DataSection.getSegmentIndex(), |
| 1713 | static_cast<uint32_t>(Layout.getSymbolOffset(S)), |
| 1714 | static_cast<uint32_t>(Size)}; |
| 1715 | DataLocations[&WS] = Ref; |
| 1716 | LLVM_DEBUG(dbgs() << " -> index:" << Ref.Segment << "\n")do { } while (false); |
| 1717 | } else { |
| 1718 | report_fatal_error("don't yet support global/tag aliases"); |
| 1719 | } |
| 1720 | } |
| 1721 | } |
| 1722 | |
| 1723 | // Finally, populate the symbol table itself, in its "natural" order. |
| 1724 | for (const MCSymbol &S : Asm.symbols()) { |
| 1725 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
| 1726 | if (!isInSymtab(WS)) { |
| 1727 | WS.setIndex(InvalidIndex); |
| 1728 | continue; |
| 1729 | } |
| 1730 | LLVM_DEBUG(dbgs() << "adding to symtab: " << WS << "\n")do { } while (false); |
| 1731 | |
| 1732 | uint32_t Flags = 0; |
| 1733 | if (WS.isWeak()) |
| 1734 | Flags |= wasm::WASM_SYMBOL_BINDING_WEAK; |
| 1735 | if (WS.isHidden()) |
| 1736 | Flags |= wasm::WASM_SYMBOL_VISIBILITY_HIDDEN; |
| 1737 | if (!WS.isExternal() && WS.isDefined()) |
| 1738 | Flags |= wasm::WASM_SYMBOL_BINDING_LOCAL; |
| 1739 | if (WS.isUndefined()) |
| 1740 | Flags |= wasm::WASM_SYMBOL_UNDEFINED; |
| 1741 | if (WS.isNoStrip()) { |
| 1742 | Flags |= wasm::WASM_SYMBOL_NO_STRIP; |
| 1743 | if (isEmscripten()) { |
| 1744 | Flags |= wasm::WASM_SYMBOL_EXPORTED; |
| 1745 | } |
| 1746 | } |
| 1747 | if (WS.hasImportName()) |
| 1748 | Flags |= wasm::WASM_SYMBOL_EXPLICIT_NAME; |
| 1749 | if (WS.hasExportName()) |
| 1750 | Flags |= wasm::WASM_SYMBOL_EXPORTED; |
| 1751 | |
| 1752 | wasm::WasmSymbolInfo Info; |
| 1753 | Info.Name = WS.getName(); |
| 1754 | Info.Kind = WS.getType().getValueOr(wasm::WASM_SYMBOL_TYPE_DATA); |
| 1755 | Info.Flags = Flags; |
| 1756 | if (!WS.isData()) { |
| 1757 | assert(WasmIndices.count(&WS) > 0)(static_cast<void> (0)); |
| 1758 | Info.ElementIndex = WasmIndices.find(&WS)->second; |
| 1759 | } else if (WS.isDefined()) { |
| 1760 | assert(DataLocations.count(&WS) > 0)(static_cast<void> (0)); |
| 1761 | Info.DataRef = DataLocations.find(&WS)->second; |
| 1762 | } |
| 1763 | WS.setIndex(SymbolInfos.size()); |
| 1764 | SymbolInfos.emplace_back(Info); |
| 1765 | } |
| 1766 | |
| 1767 | { |
| 1768 | auto HandleReloc = [&](const WasmRelocationEntry &Rel) { |
| 1769 | // Functions referenced by a relocation need to put in the table. This is |
| 1770 | // purely to make the object file's provisional values readable, and is |
| 1771 | // ignored by the linker, which re-calculates the relocations itself. |
| 1772 | if (Rel.Type != wasm::R_WASM_TABLE_INDEX_I32 && |
| 1773 | Rel.Type != wasm::R_WASM_TABLE_INDEX_I64 && |
| 1774 | Rel.Type != wasm::R_WASM_TABLE_INDEX_SLEB && |
| 1775 | Rel.Type != wasm::R_WASM_TABLE_INDEX_SLEB64 && |
| 1776 | Rel.Type != wasm::R_WASM_TABLE_INDEX_REL_SLEB && |
| 1777 | Rel.Type != wasm::R_WASM_TABLE_INDEX_REL_SLEB64) |
| 1778 | return; |
| 1779 | assert(Rel.Symbol->isFunction())(static_cast<void> (0)); |
| 1780 | const MCSymbolWasm *Base = |
| 1781 | cast<MCSymbolWasm>(Layout.getBaseSymbol(*Rel.Symbol)); |
| 1782 | uint32_t FunctionIndex = WasmIndices.find(Base)->second; |
| 1783 | uint32_t TableIndex = TableElems.size() + InitialTableOffset; |
| 1784 | if (TableIndices.try_emplace(Base, TableIndex).second) { |
| 1785 | LLVM_DEBUG(dbgs() << " -> adding " << Base->getName()do { } while (false) |
| 1786 | << " to table: " << TableIndex << "\n")do { } while (false); |
| 1787 | TableElems.push_back(FunctionIndex); |
| 1788 | registerFunctionType(*Base); |
| 1789 | } |
| 1790 | }; |
| 1791 | |
| 1792 | for (const WasmRelocationEntry &RelEntry : CodeRelocations) |
| 1793 | HandleReloc(RelEntry); |
| 1794 | for (const WasmRelocationEntry &RelEntry : DataRelocations) |
| 1795 | HandleReloc(RelEntry); |
| 1796 | } |
| 1797 | |
| 1798 | // Translate .init_array section contents into start functions. |
| 1799 | for (const MCSection &S : Asm) { |
| 1800 | const auto &WS = static_cast<const MCSectionWasm &>(S); |
| 1801 | if (WS.getName().startswith(".fini_array")) |
| 1802 | report_fatal_error(".fini_array sections are unsupported"); |
| 1803 | if (!WS.getName().startswith(".init_array")) |
| 1804 | continue; |
| 1805 | if (WS.getFragmentList().empty()) |
| 1806 | continue; |
| 1807 | |
| 1808 | // init_array is expected to contain a single non-empty data fragment |
| 1809 | if (WS.getFragmentList().size() != 3) |
| 1810 | report_fatal_error("only one .init_array section fragment supported"); |
| 1811 | |
| 1812 | auto IT = WS.begin(); |
| 1813 | const MCFragment &EmptyFrag = *IT; |
| 1814 | if (EmptyFrag.getKind() != MCFragment::FT_Data) |
| 1815 | report_fatal_error(".init_array section should be aligned"); |
| 1816 | |
| 1817 | IT = std::next(IT); |
| 1818 | const MCFragment &AlignFrag = *IT; |
| 1819 | if (AlignFrag.getKind() != MCFragment::FT_Align) |
| 1820 | report_fatal_error(".init_array section should be aligned"); |
| 1821 | if (cast<MCAlignFragment>(AlignFrag).getAlignment() != (is64Bit() ? 8 : 4)) |
| 1822 | report_fatal_error(".init_array section should be aligned for pointers"); |
| 1823 | |
| 1824 | const MCFragment &Frag = *std::next(IT); |
| 1825 | if (Frag.hasInstructions() || Frag.getKind() != MCFragment::FT_Data) |
| 1826 | report_fatal_error("only data supported in .init_array section"); |
| 1827 | |
| 1828 | uint16_t Priority = UINT16_MAX(65535); |
| 1829 | unsigned PrefixLength = strlen(".init_array"); |
| 1830 | if (WS.getName().size() > PrefixLength) { |
| 1831 | if (WS.getName()[PrefixLength] != '.') |
| 1832 | report_fatal_error( |
| 1833 | ".init_array section priority should start with '.'"); |
| 1834 | if (WS.getName().substr(PrefixLength + 1).getAsInteger(10, Priority)) |
| 1835 | report_fatal_error("invalid .init_array section priority"); |
| 1836 | } |
| 1837 | const auto &DataFrag = cast<MCDataFragment>(Frag); |
| 1838 | const SmallVectorImpl<char> &Contents = DataFrag.getContents(); |
| 1839 | for (const uint8_t * |
| 1840 | P = (const uint8_t *)Contents.data(), |
| 1841 | *End = (const uint8_t *)Contents.data() + Contents.size(); |
| 1842 | P != End; ++P) { |
| 1843 | if (*P != 0) |
| 1844 | report_fatal_error("non-symbolic data in .init_array section"); |
| 1845 | } |
| 1846 | for (const MCFixup &Fixup : DataFrag.getFixups()) { |
| 1847 | assert(Fixup.getKind() ==(static_cast<void> (0)) |
| 1848 | MCFixup::getKindForSize(is64Bit() ? 8 : 4, false))(static_cast<void> (0)); |
| 1849 | const MCExpr *Expr = Fixup.getValue(); |
| 1850 | auto *SymRef = dyn_cast<MCSymbolRefExpr>(Expr); |
| 1851 | if (!SymRef) |
| 1852 | report_fatal_error("fixups in .init_array should be symbol references"); |
| 1853 | const auto &TargetSym = cast<const MCSymbolWasm>(SymRef->getSymbol()); |
| 1854 | if (TargetSym.getIndex() == InvalidIndex) |
| 1855 | report_fatal_error("symbols in .init_array should exist in symtab"); |
| 1856 | if (!TargetSym.isFunction()) |
| 1857 | report_fatal_error("symbols in .init_array should be for functions"); |
| 1858 | InitFuncs.push_back( |
| 1859 | std::make_pair(Priority, TargetSym.getIndex())); |
| 1860 | } |
| 1861 | } |
| 1862 | |
| 1863 | // Write out the Wasm header. |
| 1864 | writeHeader(Asm); |
| 1865 | |
| 1866 | uint32_t CodeSectionIndex, DataSectionIndex; |
| 1867 | if (Mode != DwoMode::DwoOnly) { |
| 1868 | writeTypeSection(Signatures); |
| 1869 | writeImportSection(Imports, DataSize, TableElems.size()); |
| 1870 | writeFunctionSection(Functions); |
| 1871 | writeTableSection(Tables); |
| 1872 | // Skip the "memory" section; we import the memory instead. |
| 1873 | writeTagSection(Tags); |
| 1874 | writeGlobalSection(Globals); |
| 1875 | writeExportSection(Exports); |
| 1876 | const MCSymbol *IndirectFunctionTable = |
| 1877 | Asm.getContext().lookupSymbol("__indirect_function_table"); |
| 1878 | writeElemSection(cast_or_null<const MCSymbolWasm>(IndirectFunctionTable), |
| 1879 | TableElems); |
| 1880 | writeDataCountSection(); |
| 1881 | |
| 1882 | CodeSectionIndex = writeCodeSection(Asm, Layout, Functions); |
| 1883 | DataSectionIndex = writeDataSection(Layout); |
| 1884 | } |
| 1885 | |
| 1886 | // The Sections in the COMDAT list have placeholder indices (their index among |
| 1887 | // custom sections, rather than among all sections). Fix them up here. |
| 1888 | for (auto &Group : Comdats) { |
| 1889 | for (auto &Entry : Group.second) { |
| 1890 | if (Entry.Kind == wasm::WASM_COMDAT_SECTION) { |
| 1891 | Entry.Index += SectionCount; |
| 1892 | } |
| 1893 | } |
| 1894 | } |
| 1895 | for (auto &CustomSection : CustomSections) |
| 1896 | writeCustomSection(CustomSection, Asm, Layout); |
| 1897 | |
| 1898 | if (Mode != DwoMode::DwoOnly) { |
| 1899 | writeLinkingMetaDataSection(SymbolInfos, InitFuncs, Comdats); |
| 1900 | |
| 1901 | writeRelocSection(CodeSectionIndex, "CODE", CodeRelocations); |
| 1902 | writeRelocSection(DataSectionIndex, "DATA", DataRelocations); |
| 1903 | } |
| 1904 | writeCustomRelocSections(); |
| 1905 | if (ProducersSection) |
| 1906 | writeCustomSection(*ProducersSection, Asm, Layout); |
| 1907 | if (TargetFeaturesSection) |
| 1908 | writeCustomSection(*TargetFeaturesSection, Asm, Layout); |
| 1909 | |
| 1910 | // TODO: Translate the .comment section to the output. |
| 1911 | return W->OS.tell() - StartOffset; |
| 1912 | } |
| 1913 | |
| 1914 | std::unique_ptr<MCObjectWriter> |
| 1915 | llvm::createWasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW, |
| 1916 | raw_pwrite_stream &OS) { |
| 1917 | return std::make_unique<WasmObjectWriter>(std::move(MOTW), OS); |
| 1918 | } |
| 1919 | |
| 1920 | std::unique_ptr<MCObjectWriter> |
| 1921 | llvm::createWasmDwoObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW, |
| 1922 | raw_pwrite_stream &OS, |
| 1923 | raw_pwrite_stream &DwoOS) { |
| 1924 | return std::make_unique<WasmObjectWriter>(std::move(MOTW), OS, DwoOS); |
| 1925 | } |