File: | lib/MC/WasmObjectWriter.cpp |
Warning: | line 1428, column 9 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/Config/llvm-config.h" |
17 | #include "llvm/MC/MCAsmBackend.h" |
18 | #include "llvm/MC/MCAsmLayout.h" |
19 | #include "llvm/MC/MCAssembler.h" |
20 | #include "llvm/MC/MCContext.h" |
21 | #include "llvm/MC/MCExpr.h" |
22 | #include "llvm/MC/MCFixupKindInfo.h" |
23 | #include "llvm/MC/MCObjectWriter.h" |
24 | #include "llvm/MC/MCSectionWasm.h" |
25 | #include "llvm/MC/MCSymbolWasm.h" |
26 | #include "llvm/MC/MCValue.h" |
27 | #include "llvm/MC/MCWasmObjectWriter.h" |
28 | #include "llvm/Support/Casting.h" |
29 | #include "llvm/Support/Debug.h" |
30 | #include "llvm/Support/ErrorHandling.h" |
31 | #include "llvm/Support/LEB128.h" |
32 | #include "llvm/Support/StringSaver.h" |
33 | #include <vector> |
34 | |
35 | using namespace llvm; |
36 | |
37 | #define DEBUG_TYPE"mc" "mc" |
38 | |
39 | namespace { |
40 | |
41 | // Went we ceate the indirect function table we start at 1, so that there is |
42 | // and emtpy slot at 0 and therefore calling a null function pointer will trap. |
43 | static const uint32_t InitialTableOffset = 1; |
44 | |
45 | // For patching purposes, we need to remember where each section starts, both |
46 | // for patching up the section size field, and for patching up references to |
47 | // locations within the section. |
48 | struct SectionBookkeeping { |
49 | // Where the size of the section is written. |
50 | uint64_t SizeOffset; |
51 | // Where the section header ends (without custom section name). |
52 | uint64_t PayloadOffset; |
53 | // Where the contents of the section starts. |
54 | uint64_t ContentsOffset; |
55 | uint32_t Index; |
56 | }; |
57 | |
58 | // The signature of a wasm function or event, in a struct capable of being used |
59 | // as a DenseMap key. |
60 | // TODO: Consider using wasm::WasmSignature directly instead. |
61 | struct WasmSignature { |
62 | // Support empty and tombstone instances, needed by DenseMap. |
63 | enum { Plain, Empty, Tombstone } State = Plain; |
64 | |
65 | // The return types of the function. |
66 | SmallVector<wasm::ValType, 1> Returns; |
67 | |
68 | // The parameter types of the function. |
69 | SmallVector<wasm::ValType, 4> Params; |
70 | |
71 | bool operator==(const WasmSignature &Other) const { |
72 | return State == Other.State && Returns == Other.Returns && |
73 | Params == Other.Params; |
74 | } |
75 | }; |
76 | |
77 | // Traits for using WasmSignature in a DenseMap. |
78 | struct WasmSignatureDenseMapInfo { |
79 | static WasmSignature getEmptyKey() { |
80 | WasmSignature Sig; |
81 | Sig.State = WasmSignature::Empty; |
82 | return Sig; |
83 | } |
84 | static WasmSignature getTombstoneKey() { |
85 | WasmSignature Sig; |
86 | Sig.State = WasmSignature::Tombstone; |
87 | return Sig; |
88 | } |
89 | static unsigned getHashValue(const WasmSignature &Sig) { |
90 | uintptr_t Value = Sig.State; |
91 | for (wasm::ValType Ret : Sig.Returns) |
92 | Value += DenseMapInfo<uint32_t>::getHashValue(uint32_t(Ret)); |
93 | for (wasm::ValType Param : Sig.Params) |
94 | Value += DenseMapInfo<uint32_t>::getHashValue(uint32_t(Param)); |
95 | return Value; |
96 | } |
97 | static bool isEqual(const WasmSignature &LHS, const WasmSignature &RHS) { |
98 | return LHS == RHS; |
99 | } |
100 | }; |
101 | |
102 | // A wasm data segment. A wasm binary contains only a single data section |
103 | // but that can contain many segments, each with their own virtual location |
104 | // in memory. Each MCSection data created by llvm is modeled as its own |
105 | // wasm data segment. |
106 | struct WasmDataSegment { |
107 | MCSectionWasm *Section; |
108 | StringRef Name; |
109 | uint32_t InitFlags; |
110 | uint32_t Offset; |
111 | uint32_t Alignment; |
112 | uint32_t LinkerFlags; |
113 | SmallVector<char, 4> Data; |
114 | }; |
115 | |
116 | // A wasm function to be written into the function section. |
117 | struct WasmFunction { |
118 | uint32_t SigIndex; |
119 | const MCSymbolWasm *Sym; |
120 | }; |
121 | |
122 | // A wasm global to be written into the global section. |
123 | struct WasmGlobal { |
124 | wasm::WasmGlobalType Type; |
125 | uint64_t InitialValue; |
126 | }; |
127 | |
128 | // Information about a single item which is part of a COMDAT. For each data |
129 | // segment or function which is in the COMDAT, there is a corresponding |
130 | // WasmComdatEntry. |
131 | struct WasmComdatEntry { |
132 | unsigned Kind; |
133 | uint32_t Index; |
134 | }; |
135 | |
136 | // Information about a single relocation. |
137 | struct WasmRelocationEntry { |
138 | uint64_t Offset; // Where is the relocation. |
139 | const MCSymbolWasm *Symbol; // The symbol to relocate with. |
140 | int64_t Addend; // A value to add to the symbol. |
141 | unsigned Type; // The type of the relocation. |
142 | const MCSectionWasm *FixupSection; // The section the relocation is targeting. |
143 | |
144 | WasmRelocationEntry(uint64_t Offset, const MCSymbolWasm *Symbol, |
145 | int64_t Addend, unsigned Type, |
146 | const MCSectionWasm *FixupSection) |
147 | : Offset(Offset), Symbol(Symbol), Addend(Addend), Type(Type), |
148 | FixupSection(FixupSection) {} |
149 | |
150 | bool hasAddend() const { |
151 | switch (Type) { |
152 | case wasm::R_WASM_MEMORY_ADDR_LEB: |
153 | case wasm::R_WASM_MEMORY_ADDR_SLEB: |
154 | case wasm::R_WASM_MEMORY_ADDR_REL_SLEB: |
155 | case wasm::R_WASM_MEMORY_ADDR_I32: |
156 | case wasm::R_WASM_FUNCTION_OFFSET_I32: |
157 | case wasm::R_WASM_SECTION_OFFSET_I32: |
158 | return true; |
159 | default: |
160 | return false; |
161 | } |
162 | } |
163 | |
164 | void print(raw_ostream &Out) const { |
165 | Out << wasm::relocTypetoString(Type) << " Off=" << Offset |
166 | << ", Sym=" << *Symbol << ", Addend=" << Addend |
167 | << ", FixupSection=" << FixupSection->getSectionName(); |
168 | } |
169 | |
170 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) |
171 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void dump() const { print(dbgs()); } |
172 | #endif |
173 | }; |
174 | |
175 | static const uint32_t InvalidIndex = -1; |
176 | |
177 | struct WasmCustomSection { |
178 | |
179 | StringRef Name; |
180 | MCSectionWasm *Section; |
181 | |
182 | uint32_t OutputContentsOffset; |
183 | uint32_t OutputIndex; |
184 | |
185 | WasmCustomSection(StringRef Name, MCSectionWasm *Section) |
186 | : Name(Name), Section(Section), OutputContentsOffset(0), |
187 | OutputIndex(InvalidIndex) {} |
188 | }; |
189 | |
190 | #if !defined(NDEBUG) |
191 | raw_ostream &operator<<(raw_ostream &OS, const WasmRelocationEntry &Rel) { |
192 | Rel.print(OS); |
193 | return OS; |
194 | } |
195 | #endif |
196 | |
197 | // Write X as an (unsigned) LEB value at offset Offset in Stream, padded |
198 | // to allow patching. |
199 | static void writePatchableLEB(raw_pwrite_stream &Stream, uint32_t X, |
200 | uint64_t Offset) { |
201 | uint8_t Buffer[5]; |
202 | unsigned SizeLen = encodeULEB128(X, Buffer, 5); |
203 | assert(SizeLen == 5)((SizeLen == 5) ? static_cast<void> (0) : __assert_fail ("SizeLen == 5", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 203, __PRETTY_FUNCTION__)); |
204 | Stream.pwrite((char *)Buffer, SizeLen, Offset); |
205 | } |
206 | |
207 | // Write X as an signed LEB value at offset Offset in Stream, padded |
208 | // to allow patching. |
209 | static void writePatchableSLEB(raw_pwrite_stream &Stream, int32_t X, |
210 | uint64_t Offset) { |
211 | uint8_t Buffer[5]; |
212 | unsigned SizeLen = encodeSLEB128(X, Buffer, 5); |
213 | assert(SizeLen == 5)((SizeLen == 5) ? static_cast<void> (0) : __assert_fail ("SizeLen == 5", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 213, __PRETTY_FUNCTION__)); |
214 | Stream.pwrite((char *)Buffer, SizeLen, Offset); |
215 | } |
216 | |
217 | // Write X as a plain integer value at offset Offset in Stream. |
218 | static void writeI32(raw_pwrite_stream &Stream, uint32_t X, uint64_t Offset) { |
219 | uint8_t Buffer[4]; |
220 | support::endian::write32le(Buffer, X); |
221 | Stream.pwrite((char *)Buffer, sizeof(Buffer), Offset); |
222 | } |
223 | |
224 | class WasmObjectWriter : public MCObjectWriter { |
225 | support::endian::Writer W; |
226 | |
227 | /// The target specific Wasm writer instance. |
228 | std::unique_ptr<MCWasmObjectTargetWriter> TargetObjectWriter; |
229 | |
230 | // Relocations for fixing up references in the code section. |
231 | std::vector<WasmRelocationEntry> CodeRelocations; |
232 | uint32_t CodeSectionIndex; |
233 | |
234 | // Relocations for fixing up references in the data section. |
235 | std::vector<WasmRelocationEntry> DataRelocations; |
236 | uint32_t DataSectionIndex; |
237 | |
238 | // Index values to use for fixing up call_indirect type indices. |
239 | // Maps function symbols to the index of the type of the function |
240 | DenseMap<const MCSymbolWasm *, uint32_t> TypeIndices; |
241 | // Maps function symbols to the table element index space. Used |
242 | // for TABLE_INDEX relocation types (i.e. address taken functions). |
243 | DenseMap<const MCSymbolWasm *, uint32_t> TableIndices; |
244 | // Maps function/global symbols to the function/global/event/section index |
245 | // space. |
246 | DenseMap<const MCSymbolWasm *, uint32_t> WasmIndices; |
247 | DenseMap<const MCSymbolWasm *, uint32_t> GOTIndices; |
248 | // Maps data symbols to the Wasm segment and offset/size with the segment. |
249 | DenseMap<const MCSymbolWasm *, wasm::WasmDataReference> DataLocations; |
250 | |
251 | // Stores output data (index, relocations, content offset) for custom |
252 | // section. |
253 | std::vector<WasmCustomSection> CustomSections; |
254 | std::unique_ptr<WasmCustomSection> ProducersSection; |
255 | std::unique_ptr<WasmCustomSection> TargetFeaturesSection; |
256 | // Relocations for fixing up references in the custom sections. |
257 | DenseMap<const MCSectionWasm *, std::vector<WasmRelocationEntry>> |
258 | CustomSectionsRelocations; |
259 | |
260 | // Map from section to defining function symbol. |
261 | DenseMap<const MCSection *, const MCSymbol *> SectionFunctions; |
262 | |
263 | DenseMap<WasmSignature, uint32_t, WasmSignatureDenseMapInfo> SignatureIndices; |
264 | SmallVector<WasmSignature, 4> Signatures; |
265 | SmallVector<WasmDataSegment, 4> DataSegments; |
266 | unsigned NumFunctionImports = 0; |
267 | unsigned NumGlobalImports = 0; |
268 | unsigned NumEventImports = 0; |
269 | uint32_t SectionCount = 0; |
270 | |
271 | // TargetObjectWriter wrappers. |
272 | bool is64Bit() const { return TargetObjectWriter->is64Bit(); } |
273 | |
274 | void startSection(SectionBookkeeping &Section, unsigned SectionId); |
275 | void startCustomSection(SectionBookkeeping &Section, StringRef Name); |
276 | void endSection(SectionBookkeeping &Section); |
277 | |
278 | public: |
279 | WasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW, |
280 | raw_pwrite_stream &OS) |
281 | : W(OS, support::little), TargetObjectWriter(std::move(MOTW)) {} |
282 | |
283 | private: |
284 | void reset() override { |
285 | CodeRelocations.clear(); |
286 | DataRelocations.clear(); |
287 | TypeIndices.clear(); |
288 | WasmIndices.clear(); |
289 | GOTIndices.clear(); |
290 | TableIndices.clear(); |
291 | DataLocations.clear(); |
292 | CustomSections.clear(); |
293 | ProducersSection.reset(); |
294 | TargetFeaturesSection.reset(); |
295 | CustomSectionsRelocations.clear(); |
296 | SignatureIndices.clear(); |
297 | Signatures.clear(); |
298 | DataSegments.clear(); |
299 | SectionFunctions.clear(); |
300 | NumFunctionImports = 0; |
301 | NumGlobalImports = 0; |
302 | MCObjectWriter::reset(); |
303 | } |
304 | |
305 | void writeHeader(const MCAssembler &Asm); |
306 | |
307 | void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout, |
308 | const MCFragment *Fragment, const MCFixup &Fixup, |
309 | MCValue Target, uint64_t &FixedValue) override; |
310 | |
311 | void executePostLayoutBinding(MCAssembler &Asm, |
312 | const MCAsmLayout &Layout) override; |
313 | |
314 | uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override; |
315 | |
316 | void writeString(const StringRef Str) { |
317 | encodeULEB128(Str.size(), W.OS); |
318 | W.OS << Str; |
319 | } |
320 | |
321 | void writeValueType(wasm::ValType Ty) { W.OS << static_cast<char>(Ty); } |
322 | |
323 | void writeTypeSection(ArrayRef<WasmSignature> Signatures); |
324 | void writeImportSection(ArrayRef<wasm::WasmImport> Imports, uint32_t DataSize, |
325 | uint32_t NumElements); |
326 | void writeFunctionSection(ArrayRef<WasmFunction> Functions); |
327 | void writeExportSection(ArrayRef<wasm::WasmExport> Exports); |
328 | void writeElemSection(ArrayRef<uint32_t> TableElems); |
329 | void writeDataCountSection(); |
330 | void writeCodeSection(const MCAssembler &Asm, const MCAsmLayout &Layout, |
331 | ArrayRef<WasmFunction> Functions); |
332 | void writeDataSection(); |
333 | void writeEventSection(ArrayRef<wasm::WasmEventType> Events); |
334 | void writeRelocSection(uint32_t SectionIndex, StringRef Name, |
335 | std::vector<WasmRelocationEntry> &Relocations); |
336 | void writeLinkingMetaDataSection( |
337 | ArrayRef<wasm::WasmSymbolInfo> SymbolInfos, |
338 | ArrayRef<std::pair<uint16_t, uint32_t>> InitFuncs, |
339 | const std::map<StringRef, std::vector<WasmComdatEntry>> &Comdats); |
340 | void writeCustomSection(WasmCustomSection &CustomSection, |
341 | const MCAssembler &Asm, const MCAsmLayout &Layout); |
342 | void writeCustomRelocSections(); |
343 | void |
344 | updateCustomSectionRelocations(const SmallVector<WasmFunction, 4> &Functions, |
345 | const MCAsmLayout &Layout); |
346 | |
347 | uint32_t getProvisionalValue(const WasmRelocationEntry &RelEntry); |
348 | void applyRelocations(ArrayRef<WasmRelocationEntry> Relocations, |
349 | uint64_t ContentsOffset); |
350 | |
351 | uint32_t getRelocationIndexValue(const WasmRelocationEntry &RelEntry); |
352 | uint32_t getFunctionType(const MCSymbolWasm &Symbol); |
353 | uint32_t getEventType(const MCSymbolWasm &Symbol); |
354 | void registerFunctionType(const MCSymbolWasm &Symbol); |
355 | void registerEventType(const MCSymbolWasm &Symbol); |
356 | }; |
357 | |
358 | } // end anonymous namespace |
359 | |
360 | // Write out a section header and a patchable section size field. |
361 | void WasmObjectWriter::startSection(SectionBookkeeping &Section, |
362 | unsigned SectionId) { |
363 | LLVM_DEBUG(dbgs() << "startSection " << SectionId << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "startSection " << SectionId << "\n"; } } while (false); |
364 | W.OS << char(SectionId); |
365 | |
366 | Section.SizeOffset = W.OS.tell(); |
367 | |
368 | // The section size. We don't know the size yet, so reserve enough space |
369 | // for any 32-bit value; we'll patch it later. |
370 | encodeULEB128(0, W.OS, 5); |
371 | |
372 | // The position where the section starts, for measuring its size. |
373 | Section.ContentsOffset = W.OS.tell(); |
374 | Section.PayloadOffset = W.OS.tell(); |
375 | Section.Index = SectionCount++; |
376 | } |
377 | |
378 | void WasmObjectWriter::startCustomSection(SectionBookkeeping &Section, |
379 | StringRef Name) { |
380 | LLVM_DEBUG(dbgs() << "startCustomSection " << Name << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "startCustomSection " << Name << "\n"; } } while (false); |
381 | startSection(Section, wasm::WASM_SEC_CUSTOM); |
382 | |
383 | // The position where the section header ends, for measuring its size. |
384 | Section.PayloadOffset = W.OS.tell(); |
385 | |
386 | // Custom sections in wasm also have a string identifier. |
387 | writeString(Name); |
388 | |
389 | // The position where the custom section starts. |
390 | Section.ContentsOffset = W.OS.tell(); |
391 | } |
392 | |
393 | // Now that the section is complete and we know how big it is, patch up the |
394 | // section size field at the start of the section. |
395 | void WasmObjectWriter::endSection(SectionBookkeeping &Section) { |
396 | uint64_t Size = W.OS.tell(); |
397 | // /dev/null doesn't support seek/tell and can report offset of 0. |
398 | // Simply skip this patching in that case. |
399 | if (!Size) |
400 | return; |
401 | |
402 | Size -= Section.PayloadOffset; |
403 | if (uint32_t(Size) != Size) |
404 | report_fatal_error("section size does not fit in a uint32_t"); |
405 | |
406 | LLVM_DEBUG(dbgs() << "endSection size=" << Size << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "endSection size=" << Size << "\n"; } } while (false); |
407 | |
408 | // Write the final section size to the payload_len field, which follows |
409 | // the section id byte. |
410 | writePatchableLEB(static_cast<raw_pwrite_stream &>(W.OS), Size, |
411 | Section.SizeOffset); |
412 | } |
413 | |
414 | // Emit the Wasm header. |
415 | void WasmObjectWriter::writeHeader(const MCAssembler &Asm) { |
416 | W.OS.write(wasm::WasmMagic, sizeof(wasm::WasmMagic)); |
417 | W.write<uint32_t>(wasm::WasmVersion); |
418 | } |
419 | |
420 | void WasmObjectWriter::executePostLayoutBinding(MCAssembler &Asm, |
421 | const MCAsmLayout &Layout) { |
422 | // Build a map of sections to the function that defines them, for use |
423 | // in recordRelocation. |
424 | for (const MCSymbol &S : Asm.symbols()) { |
425 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
426 | if (WS.isDefined() && WS.isFunction() && !WS.isVariable()) { |
427 | const auto &Sec = static_cast<const MCSectionWasm &>(S.getSection()); |
428 | auto Pair = SectionFunctions.insert(std::make_pair(&Sec, &S)); |
429 | if (!Pair.second) |
430 | report_fatal_error("section already has a defining function: " + |
431 | Sec.getSectionName()); |
432 | } |
433 | } |
434 | } |
435 | |
436 | void WasmObjectWriter::recordRelocation(MCAssembler &Asm, |
437 | const MCAsmLayout &Layout, |
438 | const MCFragment *Fragment, |
439 | const MCFixup &Fixup, MCValue Target, |
440 | uint64_t &FixedValue) { |
441 | MCAsmBackend &Backend = Asm.getBackend(); |
442 | bool IsPCRel = Backend.getFixupKindInfo(Fixup.getKind()).Flags & |
443 | MCFixupKindInfo::FKF_IsPCRel; |
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 | |
449 | // The .init_array isn't translated as data, so don't do relocations in it. |
450 | if (FixupSection.getSectionName().startswith(".init_array")) |
451 | return; |
452 | |
453 | if (const MCSymbolRefExpr *RefB = Target.getSymB()) { |
454 | assert(RefB->getKind() == MCSymbolRefExpr::VK_None &&((RefB->getKind() == MCSymbolRefExpr::VK_None && "Should not have constructed this" ) ? static_cast<void> (0) : __assert_fail ("RefB->getKind() == MCSymbolRefExpr::VK_None && \"Should not have constructed this\"" , "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 455, __PRETTY_FUNCTION__)) |
455 | "Should not have constructed this")((RefB->getKind() == MCSymbolRefExpr::VK_None && "Should not have constructed this" ) ? static_cast<void> (0) : __assert_fail ("RefB->getKind() == MCSymbolRefExpr::VK_None && \"Should not have constructed this\"" , "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 455, __PRETTY_FUNCTION__)); |
456 | |
457 | // Let A, B and C being the components of Target and R be the location of |
458 | // the fixup. If the fixup is not pcrel, we want to compute (A - B + C). |
459 | // If it is pcrel, we want to compute (A - B + C - R). |
460 | |
461 | // In general, Wasm has no relocations for -B. It can only represent (A + C) |
462 | // or (A + C - R). If B = R + K and the relocation is not pcrel, we can |
463 | // replace B to implement it: (A - R - K + C) |
464 | if (IsPCRel) { |
465 | Ctx.reportError( |
466 | Fixup.getLoc(), |
467 | "No relocation available to represent this relative expression"); |
468 | return; |
469 | } |
470 | |
471 | const auto &SymB = cast<MCSymbolWasm>(RefB->getSymbol()); |
472 | |
473 | if (SymB.isUndefined()) { |
474 | Ctx.reportError(Fixup.getLoc(), |
475 | Twine("symbol '") + SymB.getName() + |
476 | "' can not be undefined in a subtraction expression"); |
477 | return; |
478 | } |
479 | |
480 | assert(!SymB.isAbsolute() && "Should have been folded")((!SymB.isAbsolute() && "Should have been folded") ? static_cast <void> (0) : __assert_fail ("!SymB.isAbsolute() && \"Should have been folded\"" , "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 480, __PRETTY_FUNCTION__)); |
481 | const MCSection &SecB = SymB.getSection(); |
482 | if (&SecB != &FixupSection) { |
483 | Ctx.reportError(Fixup.getLoc(), |
484 | "Cannot represent a difference across sections"); |
485 | return; |
486 | } |
487 | |
488 | uint64_t SymBOffset = Layout.getSymbolOffset(SymB); |
489 | uint64_t K = SymBOffset - FixupOffset; |
490 | IsPCRel = true; |
491 | C -= K; |
492 | } |
493 | |
494 | // We either rejected the fixup or folded B into C at this point. |
495 | const MCSymbolRefExpr *RefA = Target.getSymA(); |
496 | const auto *SymA = RefA ? cast<MCSymbolWasm>(&RefA->getSymbol()) : nullptr; |
497 | |
498 | if (SymA && SymA->isVariable()) { |
499 | const MCExpr *Expr = SymA->getVariableValue(); |
500 | const auto *Inner = cast<MCSymbolRefExpr>(Expr); |
501 | if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF) |
502 | llvm_unreachable("weakref used in reloc not yet implemented")::llvm::llvm_unreachable_internal("weakref used in reloc not yet implemented" , "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 502); |
503 | } |
504 | |
505 | // Put any constant offset in an addend. Offsets can be negative, and |
506 | // LLVM expects wrapping, in contrast to wasm's immediates which can't |
507 | // be negative and don't wrap. |
508 | FixedValue = 0; |
509 | |
510 | unsigned Type = TargetObjectWriter->getRelocType(Target, Fixup); |
511 | assert(!IsPCRel)((!IsPCRel) ? static_cast<void> (0) : __assert_fail ("!IsPCRel" , "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 511, __PRETTY_FUNCTION__)); |
512 | assert(SymA)((SymA) ? static_cast<void> (0) : __assert_fail ("SymA" , "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 512, __PRETTY_FUNCTION__)); |
513 | |
514 | // Absolute offset within a section or a function. |
515 | // Currently only supported for for metadata sections. |
516 | // See: test/MC/WebAssembly/blockaddress.ll |
517 | if (Type == wasm::R_WASM_FUNCTION_OFFSET_I32 || |
518 | Type == wasm::R_WASM_SECTION_OFFSET_I32) { |
519 | if (!FixupSection.getKind().isMetadata()) |
520 | report_fatal_error("relocations for function or section offsets are " |
521 | "only supported in metadata sections"); |
522 | |
523 | const MCSymbol *SectionSymbol = nullptr; |
524 | const MCSection &SecA = SymA->getSection(); |
525 | if (SecA.getKind().isText()) |
526 | SectionSymbol = SectionFunctions.find(&SecA)->second; |
527 | else |
528 | SectionSymbol = SecA.getBeginSymbol(); |
529 | if (!SectionSymbol) |
530 | report_fatal_error("section symbol is required for relocation"); |
531 | |
532 | C += Layout.getSymbolOffset(*SymA); |
533 | SymA = cast<MCSymbolWasm>(SectionSymbol); |
534 | } |
535 | |
536 | // Relocation other than R_WASM_TYPE_INDEX_LEB are required to be |
537 | // against a named symbol. |
538 | if (Type != wasm::R_WASM_TYPE_INDEX_LEB) { |
539 | if (SymA->getName().empty()) |
540 | report_fatal_error("relocations against un-named temporaries are not yet " |
541 | "supported by wasm"); |
542 | |
543 | SymA->setUsedInReloc(); |
544 | } |
545 | |
546 | if (RefA->getKind() == MCSymbolRefExpr::VK_GOT) |
547 | SymA->setUsedInGOT(); |
548 | |
549 | WasmRelocationEntry Rec(FixupOffset, SymA, C, Type, &FixupSection); |
550 | LLVM_DEBUG(dbgs() << "WasmReloc: " << Rec << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "WasmReloc: " << Rec << "\n"; } } while (false); |
551 | |
552 | if (FixupSection.isWasmData()) { |
553 | DataRelocations.push_back(Rec); |
554 | } else if (FixupSection.getKind().isText()) { |
555 | CodeRelocations.push_back(Rec); |
556 | } else if (FixupSection.getKind().isMetadata()) { |
557 | CustomSectionsRelocations[&FixupSection].push_back(Rec); |
558 | } else { |
559 | llvm_unreachable("unexpected section type")::llvm::llvm_unreachable_internal("unexpected section type", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 559); |
560 | } |
561 | } |
562 | |
563 | static const MCSymbolWasm *resolveSymbol(const MCSymbolWasm &Symbol) { |
564 | const MCSymbolWasm* Ret = &Symbol; |
565 | while (Ret->isVariable()) { |
566 | const MCExpr *Expr = Ret->getVariableValue(); |
567 | auto *Inner = cast<MCSymbolRefExpr>(Expr); |
568 | Ret = cast<MCSymbolWasm>(&Inner->getSymbol()); |
569 | } |
570 | return Ret; |
571 | } |
572 | |
573 | // Compute a value to write into the code at the location covered |
574 | // by RelEntry. This value isn't used by the static linker; it just serves |
575 | // to make the object format more readable and more likely to be directly |
576 | // useable. |
577 | uint32_t |
578 | WasmObjectWriter::getProvisionalValue(const WasmRelocationEntry &RelEntry) { |
579 | if (RelEntry.Type == wasm::R_WASM_GLOBAL_INDEX_LEB && !RelEntry.Symbol->isGlobal()) { |
580 | assert(GOTIndices.count(RelEntry.Symbol) > 0 && "symbol not found in GOT index space")((GOTIndices.count(RelEntry.Symbol) > 0 && "symbol not found in GOT index space" ) ? static_cast<void> (0) : __assert_fail ("GOTIndices.count(RelEntry.Symbol) > 0 && \"symbol not found in GOT index space\"" , "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 580, __PRETTY_FUNCTION__)); |
581 | return GOTIndices[RelEntry.Symbol]; |
582 | } |
583 | |
584 | switch (RelEntry.Type) { |
585 | case wasm::R_WASM_TABLE_INDEX_REL_SLEB: |
586 | case wasm::R_WASM_TABLE_INDEX_SLEB: |
587 | case wasm::R_WASM_TABLE_INDEX_I32: { |
588 | // Provisional value is table address of the resolved symbol itself |
589 | const MCSymbolWasm *Sym = resolveSymbol(*RelEntry.Symbol); |
590 | assert(Sym->isFunction())((Sym->isFunction()) ? static_cast<void> (0) : __assert_fail ("Sym->isFunction()", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 590, __PRETTY_FUNCTION__)); |
591 | return TableIndices[Sym]; |
592 | } |
593 | case wasm::R_WASM_TYPE_INDEX_LEB: |
594 | // Provisional value is same as the index |
595 | return getRelocationIndexValue(RelEntry); |
596 | case wasm::R_WASM_FUNCTION_INDEX_LEB: |
597 | case wasm::R_WASM_GLOBAL_INDEX_LEB: |
598 | case wasm::R_WASM_EVENT_INDEX_LEB: |
599 | // Provisional value is function/global/event Wasm index |
600 | assert(WasmIndices.count(RelEntry.Symbol) > 0 && "symbol not found in wasm index space")((WasmIndices.count(RelEntry.Symbol) > 0 && "symbol not found in wasm index space" ) ? static_cast<void> (0) : __assert_fail ("WasmIndices.count(RelEntry.Symbol) > 0 && \"symbol not found in wasm index space\"" , "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 600, __PRETTY_FUNCTION__)); |
601 | return WasmIndices[RelEntry.Symbol]; |
602 | case wasm::R_WASM_FUNCTION_OFFSET_I32: |
603 | case wasm::R_WASM_SECTION_OFFSET_I32: { |
604 | const auto &Section = |
605 | static_cast<const MCSectionWasm &>(RelEntry.Symbol->getSection()); |
606 | return Section.getSectionOffset() + RelEntry.Addend; |
607 | } |
608 | case wasm::R_WASM_MEMORY_ADDR_LEB: |
609 | case wasm::R_WASM_MEMORY_ADDR_I32: |
610 | case wasm::R_WASM_MEMORY_ADDR_REL_SLEB: |
611 | case wasm::R_WASM_MEMORY_ADDR_SLEB: { |
612 | // Provisional value is address of the global |
613 | const MCSymbolWasm *Sym = resolveSymbol(*RelEntry.Symbol); |
614 | // For undefined symbols, use zero |
615 | if (!Sym->isDefined()) |
616 | return 0; |
617 | const wasm::WasmDataReference &Ref = DataLocations[Sym]; |
618 | const WasmDataSegment &Segment = DataSegments[Ref.Segment]; |
619 | // Ignore overflow. LLVM allows address arithmetic to silently wrap. |
620 | return Segment.Offset + Ref.Offset + RelEntry.Addend; |
621 | } |
622 | default: |
623 | llvm_unreachable("invalid relocation type")::llvm::llvm_unreachable_internal("invalid relocation type", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 623); |
624 | } |
625 | } |
626 | |
627 | static void addData(SmallVectorImpl<char> &DataBytes, |
628 | MCSectionWasm &DataSection) { |
629 | LLVM_DEBUG(errs() << "addData: " << DataSection.getSectionName() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { errs() << "addData: " << DataSection.getSectionName () << "\n"; } } while (false); |
630 | |
631 | DataBytes.resize(alignTo(DataBytes.size(), DataSection.getAlignment())); |
632 | |
633 | for (const MCFragment &Frag : DataSection) { |
634 | if (Frag.hasInstructions()) |
635 | report_fatal_error("only data supported in data sections"); |
636 | |
637 | if (auto *Align = dyn_cast<MCAlignFragment>(&Frag)) { |
638 | if (Align->getValueSize() != 1) |
639 | report_fatal_error("only byte values supported for alignment"); |
640 | // If nops are requested, use zeros, as this is the data section. |
641 | uint8_t Value = Align->hasEmitNops() ? 0 : Align->getValue(); |
642 | uint64_t Size = |
643 | std::min<uint64_t>(alignTo(DataBytes.size(), Align->getAlignment()), |
644 | DataBytes.size() + Align->getMaxBytesToEmit()); |
645 | DataBytes.resize(Size, Value); |
646 | } else if (auto *Fill = dyn_cast<MCFillFragment>(&Frag)) { |
647 | int64_t NumValues; |
648 | if (!Fill->getNumValues().evaluateAsAbsolute(NumValues)) |
649 | llvm_unreachable("The fill should be an assembler constant")::llvm::llvm_unreachable_internal("The fill should be an assembler constant" , "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 649); |
650 | DataBytes.insert(DataBytes.end(), Fill->getValueSize() * NumValues, |
651 | Fill->getValue()); |
652 | } else if (auto *LEB = dyn_cast<MCLEBFragment>(&Frag)) { |
653 | const SmallVectorImpl<char> &Contents = LEB->getContents(); |
654 | DataBytes.insert(DataBytes.end(), Contents.begin(), Contents.end()); |
655 | } else { |
656 | const auto &DataFrag = cast<MCDataFragment>(Frag); |
657 | const SmallVectorImpl<char> &Contents = DataFrag.getContents(); |
658 | DataBytes.insert(DataBytes.end(), Contents.begin(), Contents.end()); |
659 | } |
660 | } |
661 | |
662 | LLVM_DEBUG(dbgs() << "addData -> " << DataBytes.size() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "addData -> " << DataBytes .size() << "\n"; } } while (false); |
663 | } |
664 | |
665 | uint32_t |
666 | WasmObjectWriter::getRelocationIndexValue(const WasmRelocationEntry &RelEntry) { |
667 | if (RelEntry.Type == wasm::R_WASM_TYPE_INDEX_LEB) { |
668 | if (!TypeIndices.count(RelEntry.Symbol)) |
669 | report_fatal_error("symbol not found in type index space: " + |
670 | RelEntry.Symbol->getName()); |
671 | return TypeIndices[RelEntry.Symbol]; |
672 | } |
673 | |
674 | return RelEntry.Symbol->getIndex(); |
675 | } |
676 | |
677 | // Apply the portions of the relocation records that we can handle ourselves |
678 | // directly. |
679 | void WasmObjectWriter::applyRelocations( |
680 | ArrayRef<WasmRelocationEntry> Relocations, uint64_t ContentsOffset) { |
681 | auto &Stream = static_cast<raw_pwrite_stream &>(W.OS); |
682 | for (const WasmRelocationEntry &RelEntry : Relocations) { |
683 | uint64_t Offset = ContentsOffset + |
684 | RelEntry.FixupSection->getSectionOffset() + |
685 | RelEntry.Offset; |
686 | |
687 | LLVM_DEBUG(dbgs() << "applyRelocation: " << RelEntry << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "applyRelocation: " << RelEntry << "\n"; } } while (false); |
688 | uint32_t Value = getProvisionalValue(RelEntry); |
689 | |
690 | switch (RelEntry.Type) { |
691 | case wasm::R_WASM_FUNCTION_INDEX_LEB: |
692 | case wasm::R_WASM_TYPE_INDEX_LEB: |
693 | case wasm::R_WASM_GLOBAL_INDEX_LEB: |
694 | case wasm::R_WASM_MEMORY_ADDR_LEB: |
695 | case wasm::R_WASM_EVENT_INDEX_LEB: |
696 | writePatchableLEB(Stream, Value, Offset); |
697 | break; |
698 | case wasm::R_WASM_TABLE_INDEX_I32: |
699 | case wasm::R_WASM_MEMORY_ADDR_I32: |
700 | case wasm::R_WASM_FUNCTION_OFFSET_I32: |
701 | case wasm::R_WASM_SECTION_OFFSET_I32: |
702 | writeI32(Stream, Value, Offset); |
703 | break; |
704 | case wasm::R_WASM_TABLE_INDEX_SLEB: |
705 | case wasm::R_WASM_TABLE_INDEX_REL_SLEB: |
706 | case wasm::R_WASM_MEMORY_ADDR_SLEB: |
707 | case wasm::R_WASM_MEMORY_ADDR_REL_SLEB: |
708 | writePatchableSLEB(Stream, Value, Offset); |
709 | break; |
710 | default: |
711 | llvm_unreachable("invalid relocation type")::llvm::llvm_unreachable_internal("invalid relocation type", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 711); |
712 | } |
713 | } |
714 | } |
715 | |
716 | void WasmObjectWriter::writeTypeSection(ArrayRef<WasmSignature> Signatures) { |
717 | if (Signatures.empty()) |
718 | return; |
719 | |
720 | SectionBookkeeping Section; |
721 | startSection(Section, wasm::WASM_SEC_TYPE); |
722 | |
723 | encodeULEB128(Signatures.size(), W.OS); |
724 | |
725 | for (const WasmSignature &Sig : Signatures) { |
726 | W.OS << char(wasm::WASM_TYPE_FUNC); |
727 | encodeULEB128(Sig.Params.size(), W.OS); |
728 | for (wasm::ValType Ty : Sig.Params) |
729 | writeValueType(Ty); |
730 | encodeULEB128(Sig.Returns.size(), W.OS); |
731 | for (wasm::ValType Ty : Sig.Returns) |
732 | writeValueType(Ty); |
733 | } |
734 | |
735 | endSection(Section); |
736 | } |
737 | |
738 | void WasmObjectWriter::writeImportSection(ArrayRef<wasm::WasmImport> Imports, |
739 | uint32_t DataSize, |
740 | uint32_t NumElements) { |
741 | if (Imports.empty()) |
742 | return; |
743 | |
744 | uint32_t NumPages = (DataSize + wasm::WasmPageSize - 1) / wasm::WasmPageSize; |
745 | |
746 | SectionBookkeeping Section; |
747 | startSection(Section, wasm::WASM_SEC_IMPORT); |
748 | |
749 | encodeULEB128(Imports.size(), W.OS); |
750 | for (const wasm::WasmImport &Import : Imports) { |
751 | writeString(Import.Module); |
752 | writeString(Import.Field); |
753 | W.OS << char(Import.Kind); |
754 | |
755 | switch (Import.Kind) { |
756 | case wasm::WASM_EXTERNAL_FUNCTION: |
757 | encodeULEB128(Import.SigIndex, W.OS); |
758 | break; |
759 | case wasm::WASM_EXTERNAL_GLOBAL: |
760 | W.OS << char(Import.Global.Type); |
761 | W.OS << char(Import.Global.Mutable ? 1 : 0); |
762 | break; |
763 | case wasm::WASM_EXTERNAL_MEMORY: |
764 | encodeULEB128(0, W.OS); // flags |
765 | encodeULEB128(NumPages, W.OS); // initial |
766 | break; |
767 | case wasm::WASM_EXTERNAL_TABLE: |
768 | W.OS << char(Import.Table.ElemType); |
769 | encodeULEB128(0, W.OS); // flags |
770 | encodeULEB128(NumElements, W.OS); // initial |
771 | break; |
772 | case wasm::WASM_EXTERNAL_EVENT: |
773 | encodeULEB128(Import.Event.Attribute, W.OS); |
774 | encodeULEB128(Import.Event.SigIndex, W.OS); |
775 | break; |
776 | default: |
777 | llvm_unreachable("unsupported import kind")::llvm::llvm_unreachable_internal("unsupported import kind", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 777); |
778 | } |
779 | } |
780 | |
781 | endSection(Section); |
782 | } |
783 | |
784 | void WasmObjectWriter::writeFunctionSection(ArrayRef<WasmFunction> Functions) { |
785 | if (Functions.empty()) |
786 | return; |
787 | |
788 | SectionBookkeeping Section; |
789 | startSection(Section, wasm::WASM_SEC_FUNCTION); |
790 | |
791 | encodeULEB128(Functions.size(), W.OS); |
792 | for (const WasmFunction &Func : Functions) |
793 | encodeULEB128(Func.SigIndex, W.OS); |
794 | |
795 | endSection(Section); |
796 | } |
797 | |
798 | void WasmObjectWriter::writeEventSection(ArrayRef<wasm::WasmEventType> Events) { |
799 | if (Events.empty()) |
800 | return; |
801 | |
802 | SectionBookkeeping Section; |
803 | startSection(Section, wasm::WASM_SEC_EVENT); |
804 | |
805 | encodeULEB128(Events.size(), W.OS); |
806 | for (const wasm::WasmEventType &Event : Events) { |
807 | encodeULEB128(Event.Attribute, W.OS); |
808 | encodeULEB128(Event.SigIndex, W.OS); |
809 | } |
810 | |
811 | endSection(Section); |
812 | } |
813 | |
814 | void WasmObjectWriter::writeExportSection(ArrayRef<wasm::WasmExport> Exports) { |
815 | if (Exports.empty()) |
816 | return; |
817 | |
818 | SectionBookkeeping Section; |
819 | startSection(Section, wasm::WASM_SEC_EXPORT); |
820 | |
821 | encodeULEB128(Exports.size(), W.OS); |
822 | for (const wasm::WasmExport &Export : Exports) { |
823 | writeString(Export.Name); |
824 | W.OS << char(Export.Kind); |
825 | encodeULEB128(Export.Index, W.OS); |
826 | } |
827 | |
828 | endSection(Section); |
829 | } |
830 | |
831 | void WasmObjectWriter::writeElemSection(ArrayRef<uint32_t> TableElems) { |
832 | if (TableElems.empty()) |
833 | return; |
834 | |
835 | SectionBookkeeping Section; |
836 | startSection(Section, wasm::WASM_SEC_ELEM); |
837 | |
838 | encodeULEB128(1, W.OS); // number of "segments" |
839 | encodeULEB128(0, W.OS); // the table index |
840 | |
841 | // init expr for starting offset |
842 | W.OS << char(wasm::WASM_OPCODE_I32_CONST); |
843 | encodeSLEB128(InitialTableOffset, W.OS); |
844 | W.OS << char(wasm::WASM_OPCODE_END); |
845 | |
846 | encodeULEB128(TableElems.size(), W.OS); |
847 | for (uint32_t Elem : TableElems) |
848 | encodeULEB128(Elem, W.OS); |
849 | |
850 | endSection(Section); |
851 | } |
852 | |
853 | void WasmObjectWriter::writeDataCountSection() { |
854 | if (DataSegments.empty()) |
855 | return; |
856 | |
857 | SectionBookkeeping Section; |
858 | startSection(Section, wasm::WASM_SEC_DATACOUNT); |
859 | encodeULEB128(DataSegments.size(), W.OS); |
860 | endSection(Section); |
861 | } |
862 | |
863 | void WasmObjectWriter::writeCodeSection(const MCAssembler &Asm, |
864 | const MCAsmLayout &Layout, |
865 | ArrayRef<WasmFunction> Functions) { |
866 | if (Functions.empty()) |
867 | return; |
868 | |
869 | SectionBookkeeping Section; |
870 | startSection(Section, wasm::WASM_SEC_CODE); |
871 | CodeSectionIndex = Section.Index; |
872 | |
873 | encodeULEB128(Functions.size(), W.OS); |
874 | |
875 | for (const WasmFunction &Func : Functions) { |
876 | auto &FuncSection = static_cast<MCSectionWasm &>(Func.Sym->getSection()); |
877 | |
878 | int64_t Size = 0; |
879 | if (!Func.Sym->getSize()->evaluateAsAbsolute(Size, Layout)) |
880 | report_fatal_error(".size expression must be evaluatable"); |
881 | |
882 | encodeULEB128(Size, W.OS); |
883 | FuncSection.setSectionOffset(W.OS.tell() - Section.ContentsOffset); |
884 | Asm.writeSectionData(W.OS, &FuncSection, Layout); |
885 | } |
886 | |
887 | // Apply fixups. |
888 | applyRelocations(CodeRelocations, Section.ContentsOffset); |
889 | |
890 | endSection(Section); |
891 | } |
892 | |
893 | void WasmObjectWriter::writeDataSection() { |
894 | if (DataSegments.empty()) |
895 | return; |
896 | |
897 | SectionBookkeeping Section; |
898 | startSection(Section, wasm::WASM_SEC_DATA); |
899 | DataSectionIndex = Section.Index; |
900 | |
901 | encodeULEB128(DataSegments.size(), W.OS); // count |
902 | |
903 | for (const WasmDataSegment &Segment : DataSegments) { |
904 | encodeULEB128(Segment.InitFlags, W.OS); // flags |
905 | if (Segment.InitFlags & wasm::WASM_SEGMENT_HAS_MEMINDEX) |
906 | encodeULEB128(0, W.OS); // memory index |
907 | if ((Segment.InitFlags & wasm::WASM_SEGMENT_IS_PASSIVE) == 0) { |
908 | W.OS << char(wasm::WASM_OPCODE_I32_CONST); |
909 | encodeSLEB128(Segment.Offset, W.OS); // offset |
910 | W.OS << char(wasm::WASM_OPCODE_END); |
911 | } |
912 | encodeULEB128(Segment.Data.size(), W.OS); // size |
913 | Segment.Section->setSectionOffset(W.OS.tell() - Section.ContentsOffset); |
914 | W.OS << Segment.Data; // data |
915 | } |
916 | |
917 | // Apply fixups. |
918 | applyRelocations(DataRelocations, Section.ContentsOffset); |
919 | |
920 | endSection(Section); |
921 | } |
922 | |
923 | void WasmObjectWriter::writeRelocSection( |
924 | uint32_t SectionIndex, StringRef Name, |
925 | std::vector<WasmRelocationEntry> &Relocs) { |
926 | // See: https://github.com/WebAssembly/tool-conventions/blob/master/Linking.md |
927 | // for descriptions of the reloc sections. |
928 | |
929 | if (Relocs.empty()) |
930 | return; |
931 | |
932 | // First, ensure the relocations are sorted in offset order. In general they |
933 | // should already be sorted since `recordRelocation` is called in offset |
934 | // order, but for the code section we combine many MC sections into single |
935 | // wasm section, and this order is determined by the order of Asm.Symbols() |
936 | // not the sections order. |
937 | llvm::stable_sort( |
938 | Relocs, [](const WasmRelocationEntry &A, const WasmRelocationEntry &B) { |
939 | return (A.Offset + A.FixupSection->getSectionOffset()) < |
940 | (B.Offset + B.FixupSection->getSectionOffset()); |
941 | }); |
942 | |
943 | SectionBookkeeping Section; |
944 | startCustomSection(Section, std::string("reloc.") + Name.str()); |
945 | |
946 | encodeULEB128(SectionIndex, W.OS); |
947 | encodeULEB128(Relocs.size(), W.OS); |
948 | for (const WasmRelocationEntry &RelEntry : Relocs) { |
949 | uint64_t Offset = |
950 | RelEntry.Offset + RelEntry.FixupSection->getSectionOffset(); |
951 | uint32_t Index = getRelocationIndexValue(RelEntry); |
952 | |
953 | W.OS << char(RelEntry.Type); |
954 | encodeULEB128(Offset, W.OS); |
955 | encodeULEB128(Index, W.OS); |
956 | if (RelEntry.hasAddend()) |
957 | encodeSLEB128(RelEntry.Addend, W.OS); |
958 | } |
959 | |
960 | endSection(Section); |
961 | } |
962 | |
963 | void WasmObjectWriter::writeCustomRelocSections() { |
964 | for (const auto &Sec : CustomSections) { |
965 | auto &Relocations = CustomSectionsRelocations[Sec.Section]; |
966 | writeRelocSection(Sec.OutputIndex, Sec.Name, Relocations); |
967 | } |
968 | } |
969 | |
970 | void WasmObjectWriter::writeLinkingMetaDataSection( |
971 | ArrayRef<wasm::WasmSymbolInfo> SymbolInfos, |
972 | ArrayRef<std::pair<uint16_t, uint32_t>> InitFuncs, |
973 | const std::map<StringRef, std::vector<WasmComdatEntry>> &Comdats) { |
974 | SectionBookkeeping Section; |
975 | startCustomSection(Section, "linking"); |
976 | encodeULEB128(wasm::WasmMetadataVersion, W.OS); |
977 | |
978 | SectionBookkeeping SubSection; |
979 | if (SymbolInfos.size() != 0) { |
980 | startSection(SubSection, wasm::WASM_SYMBOL_TABLE); |
981 | encodeULEB128(SymbolInfos.size(), W.OS); |
982 | for (const wasm::WasmSymbolInfo &Sym : SymbolInfos) { |
983 | encodeULEB128(Sym.Kind, W.OS); |
984 | encodeULEB128(Sym.Flags, W.OS); |
985 | switch (Sym.Kind) { |
986 | case wasm::WASM_SYMBOL_TYPE_FUNCTION: |
987 | case wasm::WASM_SYMBOL_TYPE_GLOBAL: |
988 | case wasm::WASM_SYMBOL_TYPE_EVENT: |
989 | encodeULEB128(Sym.ElementIndex, W.OS); |
990 | if ((Sym.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0 || |
991 | (Sym.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) |
992 | writeString(Sym.Name); |
993 | break; |
994 | case wasm::WASM_SYMBOL_TYPE_DATA: |
995 | writeString(Sym.Name); |
996 | if ((Sym.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0) { |
997 | encodeULEB128(Sym.DataRef.Segment, W.OS); |
998 | encodeULEB128(Sym.DataRef.Offset, W.OS); |
999 | encodeULEB128(Sym.DataRef.Size, W.OS); |
1000 | } |
1001 | break; |
1002 | case wasm::WASM_SYMBOL_TYPE_SECTION: { |
1003 | const uint32_t SectionIndex = |
1004 | CustomSections[Sym.ElementIndex].OutputIndex; |
1005 | encodeULEB128(SectionIndex, W.OS); |
1006 | break; |
1007 | } |
1008 | default: |
1009 | llvm_unreachable("unexpected kind")::llvm::llvm_unreachable_internal("unexpected kind", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1009); |
1010 | } |
1011 | } |
1012 | endSection(SubSection); |
1013 | } |
1014 | |
1015 | if (DataSegments.size()) { |
1016 | startSection(SubSection, wasm::WASM_SEGMENT_INFO); |
1017 | encodeULEB128(DataSegments.size(), W.OS); |
1018 | for (const WasmDataSegment &Segment : DataSegments) { |
1019 | writeString(Segment.Name); |
1020 | encodeULEB128(Segment.Alignment, W.OS); |
1021 | encodeULEB128(Segment.LinkerFlags, W.OS); |
1022 | } |
1023 | endSection(SubSection); |
1024 | } |
1025 | |
1026 | if (!InitFuncs.empty()) { |
1027 | startSection(SubSection, wasm::WASM_INIT_FUNCS); |
1028 | encodeULEB128(InitFuncs.size(), W.OS); |
1029 | for (auto &StartFunc : InitFuncs) { |
1030 | encodeULEB128(StartFunc.first, W.OS); // priority |
1031 | encodeULEB128(StartFunc.second, W.OS); // function index |
1032 | } |
1033 | endSection(SubSection); |
1034 | } |
1035 | |
1036 | if (Comdats.size()) { |
1037 | startSection(SubSection, wasm::WASM_COMDAT_INFO); |
1038 | encodeULEB128(Comdats.size(), W.OS); |
1039 | for (const auto &C : Comdats) { |
1040 | writeString(C.first); |
1041 | encodeULEB128(0, W.OS); // flags for future use |
1042 | encodeULEB128(C.second.size(), W.OS); |
1043 | for (const WasmComdatEntry &Entry : C.second) { |
1044 | encodeULEB128(Entry.Kind, W.OS); |
1045 | encodeULEB128(Entry.Index, W.OS); |
1046 | } |
1047 | } |
1048 | endSection(SubSection); |
1049 | } |
1050 | |
1051 | endSection(Section); |
1052 | } |
1053 | |
1054 | void WasmObjectWriter::writeCustomSection(WasmCustomSection &CustomSection, |
1055 | const MCAssembler &Asm, |
1056 | const MCAsmLayout &Layout) { |
1057 | SectionBookkeeping Section; |
1058 | auto *Sec = CustomSection.Section; |
1059 | startCustomSection(Section, CustomSection.Name); |
1060 | |
1061 | Sec->setSectionOffset(W.OS.tell() - Section.ContentsOffset); |
1062 | Asm.writeSectionData(W.OS, Sec, Layout); |
1063 | |
1064 | CustomSection.OutputContentsOffset = Section.ContentsOffset; |
1065 | CustomSection.OutputIndex = Section.Index; |
1066 | |
1067 | endSection(Section); |
1068 | |
1069 | // Apply fixups. |
1070 | auto &Relocations = CustomSectionsRelocations[CustomSection.Section]; |
1071 | applyRelocations(Relocations, CustomSection.OutputContentsOffset); |
1072 | } |
1073 | |
1074 | uint32_t WasmObjectWriter::getFunctionType(const MCSymbolWasm &Symbol) { |
1075 | assert(Symbol.isFunction())((Symbol.isFunction()) ? static_cast<void> (0) : __assert_fail ("Symbol.isFunction()", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1075, __PRETTY_FUNCTION__)); |
1076 | assert(TypeIndices.count(&Symbol))((TypeIndices.count(&Symbol)) ? static_cast<void> ( 0) : __assert_fail ("TypeIndices.count(&Symbol)", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1076, __PRETTY_FUNCTION__)); |
1077 | return TypeIndices[&Symbol]; |
1078 | } |
1079 | |
1080 | uint32_t WasmObjectWriter::getEventType(const MCSymbolWasm &Symbol) { |
1081 | assert(Symbol.isEvent())((Symbol.isEvent()) ? static_cast<void> (0) : __assert_fail ("Symbol.isEvent()", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1081, __PRETTY_FUNCTION__)); |
1082 | assert(TypeIndices.count(&Symbol))((TypeIndices.count(&Symbol)) ? static_cast<void> ( 0) : __assert_fail ("TypeIndices.count(&Symbol)", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1082, __PRETTY_FUNCTION__)); |
1083 | return TypeIndices[&Symbol]; |
1084 | } |
1085 | |
1086 | void WasmObjectWriter::registerFunctionType(const MCSymbolWasm &Symbol) { |
1087 | assert(Symbol.isFunction())((Symbol.isFunction()) ? static_cast<void> (0) : __assert_fail ("Symbol.isFunction()", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1087, __PRETTY_FUNCTION__)); |
1088 | |
1089 | WasmSignature S; |
1090 | const MCSymbolWasm *ResolvedSym = resolveSymbol(Symbol); |
1091 | if (auto *Sig = ResolvedSym->getSignature()) { |
1092 | S.Returns = Sig->Returns; |
1093 | S.Params = Sig->Params; |
1094 | } |
1095 | |
1096 | auto Pair = SignatureIndices.insert(std::make_pair(S, Signatures.size())); |
1097 | if (Pair.second) |
1098 | Signatures.push_back(S); |
1099 | TypeIndices[&Symbol] = Pair.first->second; |
1100 | |
1101 | LLVM_DEBUG(dbgs() << "registerFunctionType: " << Symboldo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "registerFunctionType: " << Symbol << " new:" << Pair.second << "\n"; } } while (false) |
1102 | << " new:" << Pair.second << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "registerFunctionType: " << Symbol << " new:" << Pair.second << "\n"; } } while (false); |
1103 | LLVM_DEBUG(dbgs() << " -> type index: " << Pair.first->second << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> type index: " << Pair .first->second << "\n"; } } while (false); |
1104 | } |
1105 | |
1106 | void WasmObjectWriter::registerEventType(const MCSymbolWasm &Symbol) { |
1107 | assert(Symbol.isEvent())((Symbol.isEvent()) ? static_cast<void> (0) : __assert_fail ("Symbol.isEvent()", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1107, __PRETTY_FUNCTION__)); |
1108 | |
1109 | // TODO Currently we don't generate imported exceptions, but if we do, we |
1110 | // should have a way of infering types of imported exceptions. |
1111 | WasmSignature S; |
1112 | if (auto *Sig = Symbol.getSignature()) { |
1113 | S.Returns = Sig->Returns; |
1114 | S.Params = Sig->Params; |
1115 | } |
1116 | |
1117 | auto Pair = SignatureIndices.insert(std::make_pair(S, Signatures.size())); |
1118 | if (Pair.second) |
1119 | Signatures.push_back(S); |
1120 | TypeIndices[&Symbol] = Pair.first->second; |
1121 | |
1122 | LLVM_DEBUG(dbgs() << "registerEventType: " << Symbol << " new:" << Pair.seconddo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "registerEventType: " << Symbol << " new:" << Pair.second << "\n"; } } while (false) |
1123 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "registerEventType: " << Symbol << " new:" << Pair.second << "\n"; } } while (false); |
1124 | LLVM_DEBUG(dbgs() << " -> type index: " << Pair.first->second << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> type index: " << Pair .first->second << "\n"; } } while (false); |
1125 | } |
1126 | |
1127 | static bool isInSymtab(const MCSymbolWasm &Sym) { |
1128 | if (Sym.isUsedInReloc()) |
1129 | return true; |
1130 | |
1131 | if (Sym.isComdat() && !Sym.isDefined()) |
1132 | return false; |
1133 | |
1134 | if (Sym.isTemporary() && Sym.getName().empty()) |
1135 | return false; |
1136 | |
1137 | if (Sym.isTemporary() && Sym.isData() && !Sym.getSize()) |
1138 | return false; |
1139 | |
1140 | if (Sym.isSection()) |
1141 | return false; |
1142 | |
1143 | return true; |
1144 | } |
1145 | |
1146 | uint64_t WasmObjectWriter::writeObject(MCAssembler &Asm, |
1147 | const MCAsmLayout &Layout) { |
1148 | uint64_t StartOffset = W.OS.tell(); |
1149 | |
1150 | LLVM_DEBUG(dbgs() << "WasmObjectWriter::writeObject\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "WasmObjectWriter::writeObject\n"; } } while (false); |
1151 | |
1152 | // Collect information from the available symbols. |
1153 | SmallVector<WasmFunction, 4> Functions; |
1154 | SmallVector<uint32_t, 4> TableElems; |
1155 | SmallVector<wasm::WasmImport, 4> Imports; |
1156 | SmallVector<wasm::WasmExport, 4> Exports; |
1157 | SmallVector<wasm::WasmEventType, 1> Events; |
1158 | SmallVector<wasm::WasmSymbolInfo, 4> SymbolInfos; |
1159 | SmallVector<std::pair<uint16_t, uint32_t>, 2> InitFuncs; |
1160 | std::map<StringRef, std::vector<WasmComdatEntry>> Comdats; |
1161 | uint32_t DataSize = 0; |
1162 | |
1163 | // For now, always emit the memory import, since loads and stores are not |
1164 | // valid without it. In the future, we could perhaps be more clever and omit |
1165 | // it if there are no loads or stores. |
1166 | wasm::WasmImport MemImport; |
1167 | MemImport.Module = "env"; |
1168 | MemImport.Field = "__linear_memory"; |
1169 | MemImport.Kind = wasm::WASM_EXTERNAL_MEMORY; |
1170 | Imports.push_back(MemImport); |
1171 | |
1172 | // For now, always emit the table section, since indirect calls are not |
1173 | // valid without it. In the future, we could perhaps be more clever and omit |
1174 | // it if there are no indirect calls. |
1175 | wasm::WasmImport TableImport; |
1176 | TableImport.Module = "env"; |
1177 | TableImport.Field = "__indirect_function_table"; |
1178 | TableImport.Kind = wasm::WASM_EXTERNAL_TABLE; |
1179 | TableImport.Table.ElemType = wasm::WASM_TYPE_FUNCREF; |
1180 | Imports.push_back(TableImport); |
1181 | |
1182 | // Populate SignatureIndices, and Imports and WasmIndices for undefined |
1183 | // symbols. This must be done before populating WasmIndices for defined |
1184 | // symbols. |
1185 | for (const MCSymbol &S : Asm.symbols()) { |
1186 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
1187 | |
1188 | // Register types for all functions, including those with private linkage |
1189 | // (because wasm always needs a type signature). |
1190 | if (WS.isFunction()) |
1191 | registerFunctionType(WS); |
1192 | |
1193 | if (WS.isEvent()) |
1194 | registerEventType(WS); |
1195 | |
1196 | if (WS.isTemporary()) |
1197 | continue; |
1198 | |
1199 | // If the symbol is not defined in this translation unit, import it. |
1200 | if (!WS.isDefined() && !WS.isComdat()) { |
1201 | if (WS.isFunction()) { |
1202 | wasm::WasmImport Import; |
1203 | Import.Module = WS.getImportModule(); |
1204 | Import.Field = WS.getImportName(); |
1205 | Import.Kind = wasm::WASM_EXTERNAL_FUNCTION; |
1206 | Import.SigIndex = getFunctionType(WS); |
1207 | Imports.push_back(Import); |
1208 | assert(WasmIndices.count(&WS) == 0)((WasmIndices.count(&WS) == 0) ? static_cast<void> ( 0) : __assert_fail ("WasmIndices.count(&WS) == 0", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1208, __PRETTY_FUNCTION__)); |
1209 | WasmIndices[&WS] = NumFunctionImports++; |
1210 | } else if (WS.isGlobal()) { |
1211 | if (WS.isWeak()) |
1212 | report_fatal_error("undefined global symbol cannot be weak"); |
1213 | |
1214 | wasm::WasmImport Import; |
1215 | Import.Field = WS.getImportName(); |
1216 | Import.Kind = wasm::WASM_EXTERNAL_GLOBAL; |
1217 | Import.Module = WS.getImportModule(); |
1218 | Import.Global = WS.getGlobalType(); |
1219 | Imports.push_back(Import); |
1220 | assert(WasmIndices.count(&WS) == 0)((WasmIndices.count(&WS) == 0) ? static_cast<void> ( 0) : __assert_fail ("WasmIndices.count(&WS) == 0", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1220, __PRETTY_FUNCTION__)); |
1221 | WasmIndices[&WS] = NumGlobalImports++; |
1222 | } else if (WS.isEvent()) { |
1223 | if (WS.isWeak()) |
1224 | report_fatal_error("undefined event symbol cannot be weak"); |
1225 | |
1226 | wasm::WasmImport Import; |
1227 | Import.Module = WS.getImportModule(); |
1228 | Import.Field = WS.getImportName(); |
1229 | Import.Kind = wasm::WASM_EXTERNAL_EVENT; |
1230 | Import.Event.Attribute = wasm::WASM_EVENT_ATTRIBUTE_EXCEPTION; |
1231 | Import.Event.SigIndex = getEventType(WS); |
1232 | Imports.push_back(Import); |
1233 | assert(WasmIndices.count(&WS) == 0)((WasmIndices.count(&WS) == 0) ? static_cast<void> ( 0) : __assert_fail ("WasmIndices.count(&WS) == 0", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1233, __PRETTY_FUNCTION__)); |
1234 | WasmIndices[&WS] = NumEventImports++; |
1235 | } |
1236 | } |
1237 | } |
1238 | |
1239 | // Add imports for GOT globals |
1240 | for (const MCSymbol &S : Asm.symbols()) { |
1241 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
1242 | if (WS.isUsedInGOT()) { |
1243 | wasm::WasmImport Import; |
1244 | if (WS.isFunction()) |
1245 | Import.Module = "GOT.func"; |
1246 | else |
1247 | Import.Module = "GOT.mem"; |
1248 | Import.Field = WS.getName(); |
1249 | Import.Kind = wasm::WASM_EXTERNAL_GLOBAL; |
1250 | Import.Global = {wasm::WASM_TYPE_I32, true}; |
1251 | Imports.push_back(Import); |
1252 | assert(GOTIndices.count(&WS) == 0)((GOTIndices.count(&WS) == 0) ? static_cast<void> ( 0) : __assert_fail ("GOTIndices.count(&WS) == 0", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1252, __PRETTY_FUNCTION__)); |
1253 | GOTIndices[&WS] = NumGlobalImports++; |
1254 | } |
1255 | } |
1256 | |
1257 | // Populate DataSegments and CustomSections, which must be done before |
1258 | // populating DataLocations. |
1259 | for (MCSection &Sec : Asm) { |
1260 | auto &Section = static_cast<MCSectionWasm &>(Sec); |
1261 | StringRef SectionName = Section.getSectionName(); |
1262 | |
1263 | // .init_array sections are handled specially elsewhere. |
1264 | if (SectionName.startswith(".init_array")) |
1265 | continue; |
1266 | |
1267 | // Code is handled separately |
1268 | if (Section.getKind().isText()) |
1269 | continue; |
1270 | |
1271 | if (Section.isWasmData()) { |
1272 | uint32_t SegmentIndex = DataSegments.size(); |
1273 | DataSize = alignTo(DataSize, Section.getAlignment()); |
1274 | DataSegments.emplace_back(); |
1275 | WasmDataSegment &Segment = DataSegments.back(); |
1276 | Segment.Name = SectionName; |
1277 | Segment.InitFlags = |
1278 | Section.getPassive() ? (uint32_t)wasm::WASM_SEGMENT_IS_PASSIVE : 0; |
1279 | Segment.Offset = DataSize; |
1280 | Segment.Section = &Section; |
1281 | addData(Segment.Data, Section); |
1282 | Segment.Alignment = Log2_32(Section.getAlignment()); |
1283 | Segment.LinkerFlags = 0; |
1284 | DataSize += Segment.Data.size(); |
1285 | Section.setSegmentIndex(SegmentIndex); |
1286 | |
1287 | if (const MCSymbolWasm *C = Section.getGroup()) { |
1288 | Comdats[C->getName()].emplace_back( |
1289 | WasmComdatEntry{wasm::WASM_COMDAT_DATA, SegmentIndex}); |
1290 | } |
1291 | } else { |
1292 | // Create custom sections |
1293 | assert(Sec.getKind().isMetadata())((Sec.getKind().isMetadata()) ? static_cast<void> (0) : __assert_fail ("Sec.getKind().isMetadata()", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1293, __PRETTY_FUNCTION__)); |
1294 | |
1295 | StringRef Name = SectionName; |
1296 | |
1297 | // For user-defined custom sections, strip the prefix |
1298 | if (Name.startswith(".custom_section.")) |
1299 | Name = Name.substr(strlen(".custom_section.")); |
1300 | |
1301 | MCSymbol *Begin = Sec.getBeginSymbol(); |
1302 | if (Begin) { |
1303 | WasmIndices[cast<MCSymbolWasm>(Begin)] = CustomSections.size(); |
1304 | if (SectionName != Begin->getName()) |
1305 | report_fatal_error("section name and begin symbol should match: " + |
1306 | Twine(SectionName)); |
1307 | } |
1308 | |
1309 | // Separate out the producers and target features sections |
1310 | if (Name == "producers") { |
1311 | ProducersSection = llvm::make_unique<WasmCustomSection>(Name, &Section); |
1312 | continue; |
1313 | } |
1314 | if (Name == "target_features") { |
1315 | TargetFeaturesSection = |
1316 | llvm::make_unique<WasmCustomSection>(Name, &Section); |
1317 | continue; |
1318 | } |
1319 | |
1320 | CustomSections.emplace_back(Name, &Section); |
1321 | } |
1322 | } |
1323 | |
1324 | // Populate WasmIndices and DataLocations for defined symbols. |
1325 | for (const MCSymbol &S : Asm.symbols()) { |
1326 | // Ignore unnamed temporary symbols, which aren't ever exported, imported, |
1327 | // or used in relocations. |
1328 | if (S.isTemporary() && S.getName().empty()) |
1329 | continue; |
1330 | |
1331 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
1332 | LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "MCSymbol: " << toString(WS.getType ()) << " '" << S << "'" << " isDefined=" << S.isDefined() << " isExternal=" << S.isExternal () << " isTemporary=" << S.isTemporary() << " isWeak=" << WS.isWeak() << " isHidden=" << WS.isHidden() << " isVariable=" << WS.isVariable () << "\n"; } } while (false) |
1333 | dbgs() << "MCSymbol: " << toString(WS.getType()) << " '" << S << "'"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "MCSymbol: " << toString(WS.getType ()) << " '" << S << "'" << " isDefined=" << S.isDefined() << " isExternal=" << S.isExternal () << " isTemporary=" << S.isTemporary() << " isWeak=" << WS.isWeak() << " isHidden=" << WS.isHidden() << " isVariable=" << WS.isVariable () << "\n"; } } while (false) |
1334 | << " isDefined=" << S.isDefined() << " isExternal="do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "MCSymbol: " << toString(WS.getType ()) << " '" << S << "'" << " isDefined=" << S.isDefined() << " isExternal=" << S.isExternal () << " isTemporary=" << S.isTemporary() << " isWeak=" << WS.isWeak() << " isHidden=" << WS.isHidden() << " isVariable=" << WS.isVariable () << "\n"; } } while (false) |
1335 | << S.isExternal() << " isTemporary=" << S.isTemporary()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "MCSymbol: " << toString(WS.getType ()) << " '" << S << "'" << " isDefined=" << S.isDefined() << " isExternal=" << S.isExternal () << " isTemporary=" << S.isTemporary() << " isWeak=" << WS.isWeak() << " isHidden=" << WS.isHidden() << " isVariable=" << WS.isVariable () << "\n"; } } while (false) |
1336 | << " isWeak=" << WS.isWeak() << " isHidden=" << WS.isHidden()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "MCSymbol: " << toString(WS.getType ()) << " '" << S << "'" << " isDefined=" << S.isDefined() << " isExternal=" << S.isExternal () << " isTemporary=" << S.isTemporary() << " isWeak=" << WS.isWeak() << " isHidden=" << WS.isHidden() << " isVariable=" << WS.isVariable () << "\n"; } } while (false) |
1337 | << " isVariable=" << WS.isVariable() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "MCSymbol: " << toString(WS.getType ()) << " '" << S << "'" << " isDefined=" << S.isDefined() << " isExternal=" << S.isExternal () << " isTemporary=" << S.isTemporary() << " isWeak=" << WS.isWeak() << " isHidden=" << WS.isHidden() << " isVariable=" << WS.isVariable () << "\n"; } } while (false); |
1338 | |
1339 | if (WS.isVariable()) |
1340 | continue; |
1341 | if (WS.isComdat() && !WS.isDefined()) |
1342 | continue; |
1343 | |
1344 | if (WS.isFunction()) { |
1345 | unsigned Index; |
1346 | if (WS.isDefined()) { |
1347 | if (WS.getOffset() != 0) |
1348 | report_fatal_error( |
1349 | "function sections must contain one function each"); |
1350 | |
1351 | if (WS.getSize() == nullptr) |
1352 | report_fatal_error( |
1353 | "function symbols must have a size set with .size"); |
1354 | |
1355 | // A definition. Write out the function body. |
1356 | Index = NumFunctionImports + Functions.size(); |
1357 | WasmFunction Func; |
1358 | Func.SigIndex = getFunctionType(WS); |
1359 | Func.Sym = &WS; |
1360 | WasmIndices[&WS] = Index; |
1361 | Functions.push_back(Func); |
1362 | |
1363 | auto &Section = static_cast<MCSectionWasm &>(WS.getSection()); |
1364 | if (const MCSymbolWasm *C = Section.getGroup()) { |
1365 | Comdats[C->getName()].emplace_back( |
1366 | WasmComdatEntry{wasm::WASM_COMDAT_FUNCTION, Index}); |
1367 | } |
1368 | } else { |
1369 | // An import; the index was assigned above. |
1370 | Index = WasmIndices.find(&WS)->second; |
1371 | } |
1372 | |
1373 | LLVM_DEBUG(dbgs() << " -> function index: " << Index << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> function index: " << Index << "\n"; } } while (false); |
1374 | |
1375 | } else if (WS.isData()) { |
1376 | if (!isInSymtab(WS)) |
1377 | continue; |
1378 | |
1379 | if (!WS.isDefined()) { |
1380 | LLVM_DEBUG(dbgs() << " -> segment index: -1"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> segment index: -1" << "\n"; } } while (false) |
1381 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> segment index: -1" << "\n"; } } while (false); |
1382 | continue; |
1383 | } |
1384 | |
1385 | if (!WS.getSize()) |
1386 | report_fatal_error("data symbols must have a size set with .size: " + |
1387 | WS.getName()); |
1388 | |
1389 | int64_t Size = 0; |
1390 | if (!WS.getSize()->evaluateAsAbsolute(Size, Layout)) |
1391 | report_fatal_error(".size expression must be evaluatable"); |
1392 | |
1393 | auto &DataSection = static_cast<MCSectionWasm &>(WS.getSection()); |
1394 | assert(DataSection.isWasmData())((DataSection.isWasmData()) ? static_cast<void> (0) : __assert_fail ("DataSection.isWasmData()", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1394, __PRETTY_FUNCTION__)); |
1395 | |
1396 | // For each data symbol, export it in the symtab as a reference to the |
1397 | // corresponding Wasm data segment. |
1398 | wasm::WasmDataReference Ref = wasm::WasmDataReference{ |
1399 | DataSection.getSegmentIndex(), |
1400 | static_cast<uint32_t>(Layout.getSymbolOffset(WS)), |
1401 | static_cast<uint32_t>(Size)}; |
1402 | DataLocations[&WS] = Ref; |
1403 | LLVM_DEBUG(dbgs() << " -> segment index: " << Ref.Segment << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> segment index: " << Ref .Segment << "\n"; } } while (false); |
1404 | |
1405 | } else if (WS.isGlobal()) { |
1406 | // A "true" Wasm global (currently just __stack_pointer) |
1407 | if (WS.isDefined()) |
1408 | report_fatal_error("don't yet support defined globals"); |
1409 | |
1410 | // An import; the index was assigned above |
1411 | LLVM_DEBUG(dbgs() << " -> global index: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> global index: " << WasmIndices .find(&WS)->second << "\n"; } } while (false) |
1412 | << WasmIndices.find(&WS)->second << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> global index: " << WasmIndices .find(&WS)->second << "\n"; } } while (false); |
1413 | |
1414 | } else if (WS.isEvent()) { |
1415 | // C++ exception symbol (__cpp_exception) |
1416 | unsigned Index; |
1417 | if (WS.isDefined()) { |
1418 | Index = NumEventImports + Events.size(); |
1419 | wasm::WasmEventType Event; |
1420 | Event.SigIndex = getEventType(WS); |
1421 | Event.Attribute = wasm::WASM_EVENT_ATTRIBUTE_EXCEPTION; |
1422 | assert(WasmIndices.count(&WS) == 0)((WasmIndices.count(&WS) == 0) ? static_cast<void> ( 0) : __assert_fail ("WasmIndices.count(&WS) == 0", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1422, __PRETTY_FUNCTION__)); |
1423 | WasmIndices[&WS] = Index; |
1424 | Events.push_back(Event); |
1425 | } else { |
1426 | // An import; the index was assigned above. |
1427 | assert(WasmIndices.count(&WS) > 0)((WasmIndices.count(&WS) > 0) ? static_cast<void> (0) : __assert_fail ("WasmIndices.count(&WS) > 0", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1427, __PRETTY_FUNCTION__)); |
1428 | Index = WasmIndices.find(&WS)->second; |
Value stored to 'Index' is never read | |
1429 | } |
1430 | LLVM_DEBUG(dbgs() << " -> event index: " << WasmIndices.find(&WS)->seconddo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> event index: " << WasmIndices .find(&WS)->second << "\n"; } } while (false) |
1431 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> event index: " << WasmIndices .find(&WS)->second << "\n"; } } while (false); |
1432 | |
1433 | } else { |
1434 | assert(WS.isSection())((WS.isSection()) ? static_cast<void> (0) : __assert_fail ("WS.isSection()", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1434, __PRETTY_FUNCTION__)); |
1435 | } |
1436 | } |
1437 | |
1438 | // Populate WasmIndices and DataLocations for aliased symbols. We need to |
1439 | // process these in a separate pass because we need to have processed the |
1440 | // target of the alias before the alias itself and the symbols are not |
1441 | // necessarily ordered in this way. |
1442 | for (const MCSymbol &S : Asm.symbols()) { |
1443 | if (!S.isVariable()) |
1444 | continue; |
1445 | |
1446 | assert(S.isDefined())((S.isDefined()) ? static_cast<void> (0) : __assert_fail ("S.isDefined()", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1446, __PRETTY_FUNCTION__)); |
1447 | |
1448 | // Find the target symbol of this weak alias and export that index |
1449 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
1450 | const MCSymbolWasm *ResolvedSym = resolveSymbol(WS); |
1451 | LLVM_DEBUG(dbgs() << WS.getName() << ": weak alias of '" << *ResolvedSymdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << WS.getName() << ": weak alias of '" << *ResolvedSym << "'\n"; } } while (false) |
1452 | << "'\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << WS.getName() << ": weak alias of '" << *ResolvedSym << "'\n"; } } while (false); |
1453 | |
1454 | if (ResolvedSym->isFunction()) { |
1455 | assert(WasmIndices.count(ResolvedSym) > 0)((WasmIndices.count(ResolvedSym) > 0) ? static_cast<void > (0) : __assert_fail ("WasmIndices.count(ResolvedSym) > 0" , "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1455, __PRETTY_FUNCTION__)); |
1456 | uint32_t WasmIndex = WasmIndices.find(ResolvedSym)->second; |
1457 | assert(WasmIndices.count(&WS) == 0)((WasmIndices.count(&WS) == 0) ? static_cast<void> ( 0) : __assert_fail ("WasmIndices.count(&WS) == 0", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1457, __PRETTY_FUNCTION__)); |
1458 | WasmIndices[&WS] = WasmIndex; |
1459 | LLVM_DEBUG(dbgs() << " -> index:" << WasmIndex << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> index:" << WasmIndex << "\n"; } } while (false); |
1460 | } else if (ResolvedSym->isData()) { |
1461 | assert(DataLocations.count(ResolvedSym) > 0)((DataLocations.count(ResolvedSym) > 0) ? static_cast<void > (0) : __assert_fail ("DataLocations.count(ResolvedSym) > 0" , "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1461, __PRETTY_FUNCTION__)); |
1462 | const wasm::WasmDataReference &Ref = |
1463 | DataLocations.find(ResolvedSym)->second; |
1464 | DataLocations[&WS] = Ref; |
1465 | LLVM_DEBUG(dbgs() << " -> index:" << Ref.Segment << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> index:" << Ref.Segment << "\n"; } } while (false); |
1466 | } else { |
1467 | report_fatal_error("don't yet support global/event aliases"); |
1468 | } |
1469 | } |
1470 | |
1471 | // Finally, populate the symbol table itself, in its "natural" order. |
1472 | for (const MCSymbol &S : Asm.symbols()) { |
1473 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
1474 | if (!isInSymtab(WS)) { |
1475 | WS.setIndex(InvalidIndex); |
1476 | continue; |
1477 | } |
1478 | LLVM_DEBUG(dbgs() << "adding to symtab: " << WS << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "adding to symtab: " << WS << "\n"; } } while (false); |
1479 | |
1480 | uint32_t Flags = 0; |
1481 | if (WS.isWeak()) |
1482 | Flags |= wasm::WASM_SYMBOL_BINDING_WEAK; |
1483 | if (WS.isHidden()) |
1484 | Flags |= wasm::WASM_SYMBOL_VISIBILITY_HIDDEN; |
1485 | if (!WS.isExternal() && WS.isDefined()) |
1486 | Flags |= wasm::WASM_SYMBOL_BINDING_LOCAL; |
1487 | if (WS.isUndefined()) |
1488 | Flags |= wasm::WASM_SYMBOL_UNDEFINED; |
1489 | if (WS.isExported()) |
1490 | Flags |= wasm::WASM_SYMBOL_EXPORTED; |
1491 | if (WS.getName() != WS.getImportName()) |
1492 | Flags |= wasm::WASM_SYMBOL_EXPLICIT_NAME; |
1493 | |
1494 | wasm::WasmSymbolInfo Info; |
1495 | Info.Name = WS.getName(); |
1496 | Info.Kind = WS.getType(); |
1497 | Info.Flags = Flags; |
1498 | if (!WS.isData()) { |
1499 | assert(WasmIndices.count(&WS) > 0)((WasmIndices.count(&WS) > 0) ? static_cast<void> (0) : __assert_fail ("WasmIndices.count(&WS) > 0", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1499, __PRETTY_FUNCTION__)); |
1500 | Info.ElementIndex = WasmIndices.find(&WS)->second; |
1501 | } else if (WS.isDefined()) { |
1502 | assert(DataLocations.count(&WS) > 0)((DataLocations.count(&WS) > 0) ? static_cast<void> (0) : __assert_fail ("DataLocations.count(&WS) > 0", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1502, __PRETTY_FUNCTION__)); |
1503 | Info.DataRef = DataLocations.find(&WS)->second; |
1504 | } |
1505 | WS.setIndex(SymbolInfos.size()); |
1506 | SymbolInfos.emplace_back(Info); |
1507 | } |
1508 | |
1509 | { |
1510 | auto HandleReloc = [&](const WasmRelocationEntry &Rel) { |
1511 | // Functions referenced by a relocation need to put in the table. This is |
1512 | // purely to make the object file's provisional values readable, and is |
1513 | // ignored by the linker, which re-calculates the relocations itself. |
1514 | if (Rel.Type != wasm::R_WASM_TABLE_INDEX_I32 && |
1515 | Rel.Type != wasm::R_WASM_TABLE_INDEX_SLEB) |
1516 | return; |
1517 | assert(Rel.Symbol->isFunction())((Rel.Symbol->isFunction()) ? static_cast<void> (0) : __assert_fail ("Rel.Symbol->isFunction()", "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1517, __PRETTY_FUNCTION__)); |
1518 | const MCSymbolWasm &WS = *resolveSymbol(*Rel.Symbol); |
1519 | uint32_t FunctionIndex = WasmIndices.find(&WS)->second; |
1520 | uint32_t TableIndex = TableElems.size() + InitialTableOffset; |
1521 | if (TableIndices.try_emplace(&WS, TableIndex).second) { |
1522 | LLVM_DEBUG(dbgs() << " -> adding " << WS.getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> adding " << WS.getName () << " to table: " << TableIndex << "\n"; } } while (false) |
1523 | << " to table: " << TableIndex << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> adding " << WS.getName () << " to table: " << TableIndex << "\n"; } } while (false); |
1524 | TableElems.push_back(FunctionIndex); |
1525 | registerFunctionType(WS); |
1526 | } |
1527 | }; |
1528 | |
1529 | for (const WasmRelocationEntry &RelEntry : CodeRelocations) |
1530 | HandleReloc(RelEntry); |
1531 | for (const WasmRelocationEntry &RelEntry : DataRelocations) |
1532 | HandleReloc(RelEntry); |
1533 | } |
1534 | |
1535 | // Translate .init_array section contents into start functions. |
1536 | for (const MCSection &S : Asm) { |
1537 | const auto &WS = static_cast<const MCSectionWasm &>(S); |
1538 | if (WS.getSectionName().startswith(".fini_array")) |
1539 | report_fatal_error(".fini_array sections are unsupported"); |
1540 | if (!WS.getSectionName().startswith(".init_array")) |
1541 | continue; |
1542 | if (WS.getFragmentList().empty()) |
1543 | continue; |
1544 | |
1545 | // init_array is expected to contain a single non-empty data fragment |
1546 | if (WS.getFragmentList().size() != 3) |
1547 | report_fatal_error("only one .init_array section fragment supported"); |
1548 | |
1549 | auto IT = WS.begin(); |
1550 | const MCFragment &EmptyFrag = *IT; |
1551 | if (EmptyFrag.getKind() != MCFragment::FT_Data) |
1552 | report_fatal_error(".init_array section should be aligned"); |
1553 | |
1554 | IT = std::next(IT); |
1555 | const MCFragment &AlignFrag = *IT; |
1556 | if (AlignFrag.getKind() != MCFragment::FT_Align) |
1557 | report_fatal_error(".init_array section should be aligned"); |
1558 | if (cast<MCAlignFragment>(AlignFrag).getAlignment() != (is64Bit() ? 8 : 4)) |
1559 | report_fatal_error(".init_array section should be aligned for pointers"); |
1560 | |
1561 | const MCFragment &Frag = *std::next(IT); |
1562 | if (Frag.hasInstructions() || Frag.getKind() != MCFragment::FT_Data) |
1563 | report_fatal_error("only data supported in .init_array section"); |
1564 | |
1565 | uint16_t Priority = UINT16_MAX(65535); |
1566 | unsigned PrefixLength = strlen(".init_array"); |
1567 | if (WS.getSectionName().size() > PrefixLength) { |
1568 | if (WS.getSectionName()[PrefixLength] != '.') |
1569 | report_fatal_error( |
1570 | ".init_array section priority should start with '.'"); |
1571 | if (WS.getSectionName() |
1572 | .substr(PrefixLength + 1) |
1573 | .getAsInteger(10, Priority)) |
1574 | report_fatal_error("invalid .init_array section priority"); |
1575 | } |
1576 | const auto &DataFrag = cast<MCDataFragment>(Frag); |
1577 | const SmallVectorImpl<char> &Contents = DataFrag.getContents(); |
1578 | for (const uint8_t * |
1579 | P = (const uint8_t *)Contents.data(), |
1580 | *End = (const uint8_t *)Contents.data() + Contents.size(); |
1581 | P != End; ++P) { |
1582 | if (*P != 0) |
1583 | report_fatal_error("non-symbolic data in .init_array section"); |
1584 | } |
1585 | for (const MCFixup &Fixup : DataFrag.getFixups()) { |
1586 | assert(Fixup.getKind() ==((Fixup.getKind() == MCFixup::getKindForSize(is64Bit() ? 8 : 4 , false)) ? static_cast<void> (0) : __assert_fail ("Fixup.getKind() == MCFixup::getKindForSize(is64Bit() ? 8 : 4, false)" , "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1587, __PRETTY_FUNCTION__)) |
1587 | MCFixup::getKindForSize(is64Bit() ? 8 : 4, false))((Fixup.getKind() == MCFixup::getKindForSize(is64Bit() ? 8 : 4 , false)) ? static_cast<void> (0) : __assert_fail ("Fixup.getKind() == MCFixup::getKindForSize(is64Bit() ? 8 : 4, false)" , "/build/llvm-toolchain-snapshot-9~svn362543/lib/MC/WasmObjectWriter.cpp" , 1587, __PRETTY_FUNCTION__)); |
1588 | const MCExpr *Expr = Fixup.getValue(); |
1589 | auto *SymRef = dyn_cast<MCSymbolRefExpr>(Expr); |
1590 | if (!SymRef) |
1591 | report_fatal_error("fixups in .init_array should be symbol references"); |
1592 | const auto &TargetSym = cast<const MCSymbolWasm>(SymRef->getSymbol()); |
1593 | if (TargetSym.getIndex() == InvalidIndex) |
1594 | report_fatal_error("symbols in .init_array should exist in symbtab"); |
1595 | if (!TargetSym.isFunction()) |
1596 | report_fatal_error("symbols in .init_array should be for functions"); |
1597 | InitFuncs.push_back( |
1598 | std::make_pair(Priority, TargetSym.getIndex())); |
1599 | } |
1600 | } |
1601 | |
1602 | // Write out the Wasm header. |
1603 | writeHeader(Asm); |
1604 | |
1605 | writeTypeSection(Signatures); |
1606 | writeImportSection(Imports, DataSize, TableElems.size()); |
1607 | writeFunctionSection(Functions); |
1608 | // Skip the "table" section; we import the table instead. |
1609 | // Skip the "memory" section; we import the memory instead. |
1610 | writeEventSection(Events); |
1611 | writeExportSection(Exports); |
1612 | writeElemSection(TableElems); |
1613 | writeDataCountSection(); |
1614 | writeCodeSection(Asm, Layout, Functions); |
1615 | writeDataSection(); |
1616 | for (auto &CustomSection : CustomSections) |
1617 | writeCustomSection(CustomSection, Asm, Layout); |
1618 | writeLinkingMetaDataSection(SymbolInfos, InitFuncs, Comdats); |
1619 | writeRelocSection(CodeSectionIndex, "CODE", CodeRelocations); |
1620 | writeRelocSection(DataSectionIndex, "DATA", DataRelocations); |
1621 | writeCustomRelocSections(); |
1622 | if (ProducersSection) |
1623 | writeCustomSection(*ProducersSection, Asm, Layout); |
1624 | if (TargetFeaturesSection) |
1625 | writeCustomSection(*TargetFeaturesSection, Asm, Layout); |
1626 | |
1627 | // TODO: Translate the .comment section to the output. |
1628 | return W.OS.tell() - StartOffset; |
1629 | } |
1630 | |
1631 | std::unique_ptr<MCObjectWriter> |
1632 | llvm::createWasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW, |
1633 | raw_pwrite_stream &OS) { |
1634 | return llvm::make_unique<WasmObjectWriter>(std::move(MOTW), OS); |
1635 | } |