File: | lib/MC/WasmObjectWriter.cpp |
Warning: | line 1391, column 9 Value stored to 'Index' is never read |
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1 | //===- lib/MC/WasmObjectWriter.cpp - Wasm File Writer ---------------------===// |
2 | // |
3 | // The LLVM Compiler Infrastructure |
4 | // |
5 | // This file is distributed under the University of Illinois Open Source |
6 | // License. See LICENSE.TXT for details. |
7 | // |
8 | //===----------------------------------------------------------------------===// |
9 | // |
10 | // This file implements Wasm object file writer information. |
11 | // |
12 | //===----------------------------------------------------------------------===// |
13 | |
14 | #include "llvm/ADT/STLExtras.h" |
15 | #include "llvm/ADT/SmallPtrSet.h" |
16 | #include "llvm/BinaryFormat/Wasm.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/ErrorHandling.h" |
32 | #include "llvm/Support/LEB128.h" |
33 | #include "llvm/Support/StringSaver.h" |
34 | #include <vector> |
35 | |
36 | using namespace llvm; |
37 | |
38 | #define DEBUG_TYPE"mc" "mc" |
39 | |
40 | namespace { |
41 | |
42 | // Went we ceate the indirect function table we start at 1, so that there is |
43 | // and emtpy slot at 0 and therefore calling a null function pointer will trap. |
44 | static const uint32_t kInitialTableOffset = 1; |
45 | |
46 | // For patching purposes, we need to remember where each section starts, both |
47 | // for patching up the section size field, and for patching up references to |
48 | // locations within the section. |
49 | struct SectionBookkeeping { |
50 | // Where the size of the section is written. |
51 | uint64_t SizeOffset; |
52 | // Where the section header ends (without custom section name). |
53 | uint64_t PayloadOffset; |
54 | // Where the contents of the section starts. |
55 | uint64_t ContentsOffset; |
56 | uint32_t Index; |
57 | }; |
58 | |
59 | // The signature of a wasm function or event, in a struct capable of being used |
60 | // as a DenseMap key. |
61 | // TODO: Consider using wasm::WasmSignature directly instead. |
62 | struct WasmSignature { |
63 | // Support empty and tombstone instances, needed by DenseMap. |
64 | enum { Plain, Empty, Tombstone } State; |
65 | |
66 | // The return types of the function. |
67 | SmallVector<wasm::ValType, 1> Returns; |
68 | |
69 | // The parameter types of the function. |
70 | SmallVector<wasm::ValType, 4> Params; |
71 | |
72 | WasmSignature() : State(Plain) {} |
73 | |
74 | bool operator==(const WasmSignature &Other) const { |
75 | return State == Other.State && Returns == Other.Returns && |
76 | Params == Other.Params; |
77 | } |
78 | }; |
79 | |
80 | // Traits for using WasmSignature in a DenseMap. |
81 | struct WasmSignatureDenseMapInfo { |
82 | static WasmSignature getEmptyKey() { |
83 | WasmSignature Sig; |
84 | Sig.State = WasmSignature::Empty; |
85 | return Sig; |
86 | } |
87 | static WasmSignature getTombstoneKey() { |
88 | WasmSignature Sig; |
89 | Sig.State = WasmSignature::Tombstone; |
90 | return Sig; |
91 | } |
92 | static unsigned getHashValue(const WasmSignature &Sig) { |
93 | uintptr_t Value = Sig.State; |
94 | for (wasm::ValType Ret : Sig.Returns) |
95 | Value += DenseMapInfo<uint32_t>::getHashValue(uint32_t(Ret)); |
96 | for (wasm::ValType Param : Sig.Params) |
97 | Value += DenseMapInfo<uint32_t>::getHashValue(uint32_t(Param)); |
98 | return Value; |
99 | } |
100 | static bool isEqual(const WasmSignature &LHS, const WasmSignature &RHS) { |
101 | return LHS == RHS; |
102 | } |
103 | }; |
104 | |
105 | // A wasm data segment. A wasm binary contains only a single data section |
106 | // but that can contain many segments, each with their own virtual location |
107 | // in memory. Each MCSection data created by llvm is modeled as its own |
108 | // wasm data segment. |
109 | struct WasmDataSegment { |
110 | MCSectionWasm *Section; |
111 | StringRef Name; |
112 | uint32_t Offset; |
113 | uint32_t Alignment; |
114 | uint32_t Flags; |
115 | SmallVector<char, 4> Data; |
116 | }; |
117 | |
118 | // A wasm function to be written into the function section. |
119 | struct WasmFunction { |
120 | uint32_t SigIndex; |
121 | const MCSymbolWasm *Sym; |
122 | }; |
123 | |
124 | // A wasm global to be written into the global section. |
125 | struct WasmGlobal { |
126 | wasm::WasmGlobalType Type; |
127 | uint64_t InitialValue; |
128 | }; |
129 | |
130 | // Information about a single item which is part of a COMDAT. For each data |
131 | // segment or function which is in the COMDAT, there is a corresponding |
132 | // WasmComdatEntry. |
133 | struct WasmComdatEntry { |
134 | unsigned Kind; |
135 | uint32_t Index; |
136 | }; |
137 | |
138 | // Information about a single relocation. |
139 | struct WasmRelocationEntry { |
140 | uint64_t Offset; // Where is the relocation. |
141 | const MCSymbolWasm *Symbol; // The symbol to relocate with. |
142 | int64_t Addend; // A value to add to the symbol. |
143 | unsigned Type; // The type of the relocation. |
144 | const MCSectionWasm *FixupSection; // The section the relocation is targeting. |
145 | |
146 | WasmRelocationEntry(uint64_t Offset, const MCSymbolWasm *Symbol, |
147 | int64_t Addend, unsigned Type, |
148 | const MCSectionWasm *FixupSection) |
149 | : Offset(Offset), Symbol(Symbol), Addend(Addend), Type(Type), |
150 | FixupSection(FixupSection) {} |
151 | |
152 | bool hasAddend() const { |
153 | switch (Type) { |
154 | case wasm::R_WEBASSEMBLY_MEMORY_ADDR_LEB: |
155 | case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB: |
156 | case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32: |
157 | case wasm::R_WEBASSEMBLY_FUNCTION_OFFSET_I32: |
158 | case wasm::R_WEBASSEMBLY_SECTION_OFFSET_I32: |
159 | return true; |
160 | default: |
161 | return false; |
162 | } |
163 | } |
164 | |
165 | void print(raw_ostream &Out) const { |
166 | Out << wasm::relocTypetoString(Type) << " Off=" << Offset |
167 | << ", Sym=" << *Symbol << ", Addend=" << Addend |
168 | << ", FixupSection=" << FixupSection->getSectionName(); |
169 | } |
170 | |
171 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) |
172 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void dump() const { print(dbgs()); } |
173 | #endif |
174 | }; |
175 | |
176 | static const uint32_t INVALID_INDEX = -1; |
177 | |
178 | struct WasmCustomSection { |
179 | |
180 | StringRef Name; |
181 | MCSectionWasm *Section; |
182 | |
183 | uint32_t OutputContentsOffset; |
184 | uint32_t OutputIndex; |
185 | |
186 | WasmCustomSection(StringRef Name, MCSectionWasm *Section) |
187 | : Name(Name), Section(Section), OutputContentsOffset(0), |
188 | OutputIndex(INVALID_INDEX) {} |
189 | }; |
190 | |
191 | #if !defined(NDEBUG) |
192 | raw_ostream &operator<<(raw_ostream &OS, const WasmRelocationEntry &Rel) { |
193 | Rel.print(OS); |
194 | return OS; |
195 | } |
196 | #endif |
197 | |
198 | class WasmObjectWriter : public MCObjectWriter { |
199 | support::endian::Writer W; |
200 | |
201 | /// The target specific Wasm writer instance. |
202 | std::unique_ptr<MCWasmObjectTargetWriter> TargetObjectWriter; |
203 | |
204 | // Relocations for fixing up references in the code section. |
205 | std::vector<WasmRelocationEntry> CodeRelocations; |
206 | uint32_t CodeSectionIndex; |
207 | |
208 | // Relocations for fixing up references in the data section. |
209 | std::vector<WasmRelocationEntry> DataRelocations; |
210 | uint32_t DataSectionIndex; |
211 | |
212 | // Index values to use for fixing up call_indirect type indices. |
213 | // Maps function symbols to the index of the type of the function |
214 | DenseMap<const MCSymbolWasm *, uint32_t> TypeIndices; |
215 | // Maps function symbols to the table element index space. Used |
216 | // for TABLE_INDEX relocation types (i.e. address taken functions). |
217 | DenseMap<const MCSymbolWasm *, uint32_t> TableIndices; |
218 | // Maps function/global symbols to the function/global/event/section index |
219 | // space. |
220 | DenseMap<const MCSymbolWasm *, uint32_t> WasmIndices; |
221 | // Maps data symbols to the Wasm segment and offset/size with the segment. |
222 | DenseMap<const MCSymbolWasm *, wasm::WasmDataReference> DataLocations; |
223 | |
224 | // Stores output data (index, relocations, content offset) for custom |
225 | // section. |
226 | std::vector<WasmCustomSection> CustomSections; |
227 | // Relocations for fixing up references in the custom sections. |
228 | DenseMap<const MCSectionWasm *, std::vector<WasmRelocationEntry>> |
229 | CustomSectionsRelocations; |
230 | |
231 | // Map from section to defining function symbol. |
232 | DenseMap<const MCSection *, const MCSymbol *> SectionFunctions; |
233 | |
234 | DenseMap<WasmSignature, uint32_t, WasmSignatureDenseMapInfo> SignatureIndices; |
235 | SmallVector<WasmSignature, 4> Signatures; |
236 | SmallVector<WasmGlobal, 4> Globals; |
237 | SmallVector<WasmDataSegment, 4> DataSegments; |
238 | unsigned NumFunctionImports = 0; |
239 | unsigned NumGlobalImports = 0; |
240 | unsigned NumEventImports = 0; |
241 | uint32_t SectionCount = 0; |
242 | |
243 | // TargetObjectWriter wrappers. |
244 | bool is64Bit() const { return TargetObjectWriter->is64Bit(); } |
245 | unsigned getRelocType(const MCValue &Target, const MCFixup &Fixup) const { |
246 | return TargetObjectWriter->getRelocType(Target, Fixup); |
247 | } |
248 | |
249 | void startSection(SectionBookkeeping &Section, unsigned SectionId); |
250 | void startCustomSection(SectionBookkeeping &Section, StringRef Name); |
251 | void endSection(SectionBookkeeping &Section); |
252 | |
253 | public: |
254 | WasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW, |
255 | raw_pwrite_stream &OS) |
256 | : W(OS, support::little), TargetObjectWriter(std::move(MOTW)) {} |
257 | |
258 | ~WasmObjectWriter() override; |
259 | |
260 | private: |
261 | void reset() override { |
262 | CodeRelocations.clear(); |
263 | DataRelocations.clear(); |
264 | TypeIndices.clear(); |
265 | WasmIndices.clear(); |
266 | TableIndices.clear(); |
267 | DataLocations.clear(); |
268 | CustomSectionsRelocations.clear(); |
269 | SignatureIndices.clear(); |
270 | Signatures.clear(); |
271 | Globals.clear(); |
272 | DataSegments.clear(); |
273 | SectionFunctions.clear(); |
274 | NumFunctionImports = 0; |
275 | NumGlobalImports = 0; |
276 | MCObjectWriter::reset(); |
277 | } |
278 | |
279 | void writeHeader(const MCAssembler &Asm); |
280 | |
281 | void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout, |
282 | const MCFragment *Fragment, const MCFixup &Fixup, |
283 | MCValue Target, uint64_t &FixedValue) override; |
284 | |
285 | void executePostLayoutBinding(MCAssembler &Asm, |
286 | const MCAsmLayout &Layout) override; |
287 | |
288 | uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override; |
289 | |
290 | void writeString(const StringRef Str) { |
291 | encodeULEB128(Str.size(), W.OS); |
292 | W.OS << Str; |
293 | } |
294 | |
295 | void writeValueType(wasm::ValType Ty) { W.OS << static_cast<char>(Ty); } |
296 | |
297 | void writeTypeSection(ArrayRef<WasmSignature> Signatures); |
298 | void writeImportSection(ArrayRef<wasm::WasmImport> Imports, uint32_t DataSize, |
299 | uint32_t NumElements); |
300 | void writeFunctionSection(ArrayRef<WasmFunction> Functions); |
301 | void writeGlobalSection(); |
302 | void writeExportSection(ArrayRef<wasm::WasmExport> Exports); |
303 | void writeElemSection(ArrayRef<uint32_t> TableElems); |
304 | void writeCodeSection(const MCAssembler &Asm, const MCAsmLayout &Layout, |
305 | ArrayRef<WasmFunction> Functions); |
306 | void writeDataSection(); |
307 | void writeEventSection(ArrayRef<wasm::WasmEventType> Events); |
308 | void writeRelocSection(uint32_t SectionIndex, StringRef Name, |
309 | std::vector<WasmRelocationEntry> &Relocations); |
310 | void writeLinkingMetaDataSection( |
311 | ArrayRef<wasm::WasmSymbolInfo> SymbolInfos, |
312 | ArrayRef<std::pair<uint16_t, uint32_t>> InitFuncs, |
313 | const std::map<StringRef, std::vector<WasmComdatEntry>> &Comdats); |
314 | void writeCustomSections(const MCAssembler &Asm, const MCAsmLayout &Layout); |
315 | void writeCustomRelocSections(); |
316 | void |
317 | updateCustomSectionRelocations(const SmallVector<WasmFunction, 4> &Functions, |
318 | const MCAsmLayout &Layout); |
319 | |
320 | uint32_t getProvisionalValue(const WasmRelocationEntry &RelEntry); |
321 | void applyRelocations(ArrayRef<WasmRelocationEntry> Relocations, |
322 | uint64_t ContentsOffset); |
323 | |
324 | uint32_t getRelocationIndexValue(const WasmRelocationEntry &RelEntry); |
325 | uint32_t getFunctionType(const MCSymbolWasm &Symbol); |
326 | uint32_t getEventType(const MCSymbolWasm &Symbol); |
327 | void registerFunctionType(const MCSymbolWasm &Symbol); |
328 | void registerEventType(const MCSymbolWasm &Symbol); |
329 | }; |
330 | |
331 | } // end anonymous namespace |
332 | |
333 | WasmObjectWriter::~WasmObjectWriter() {} |
334 | |
335 | // Write out a section header and a patchable section size field. |
336 | void WasmObjectWriter::startSection(SectionBookkeeping &Section, |
337 | unsigned SectionId) { |
338 | LLVM_DEBUG(dbgs() << "startSection " << SectionId << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "startSection " << SectionId << "\n"; } } while (false); |
339 | W.OS << char(SectionId); |
340 | |
341 | Section.SizeOffset = W.OS.tell(); |
342 | |
343 | // The section size. We don't know the size yet, so reserve enough space |
344 | // for any 32-bit value; we'll patch it later. |
345 | encodeULEB128(UINT32_MAX(4294967295U), W.OS); |
346 | |
347 | // The position where the section starts, for measuring its size. |
348 | Section.ContentsOffset = W.OS.tell(); |
349 | Section.PayloadOffset = W.OS.tell(); |
350 | Section.Index = SectionCount++; |
351 | } |
352 | |
353 | void WasmObjectWriter::startCustomSection(SectionBookkeeping &Section, |
354 | StringRef Name) { |
355 | LLVM_DEBUG(dbgs() << "startCustomSection " << Name << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "startCustomSection " << Name << "\n"; } } while (false); |
356 | startSection(Section, wasm::WASM_SEC_CUSTOM); |
357 | |
358 | // The position where the section header ends, for measuring its size. |
359 | Section.PayloadOffset = W.OS.tell(); |
360 | |
361 | // Custom sections in wasm also have a string identifier. |
362 | writeString(Name); |
363 | |
364 | // The position where the custom section starts. |
365 | Section.ContentsOffset = W.OS.tell(); |
366 | } |
367 | |
368 | // Now that the section is complete and we know how big it is, patch up the |
369 | // section size field at the start of the section. |
370 | void WasmObjectWriter::endSection(SectionBookkeeping &Section) { |
371 | uint64_t Size = W.OS.tell() - Section.PayloadOffset; |
372 | if (uint32_t(Size) != Size) |
373 | report_fatal_error("section size does not fit in a uint32_t"); |
374 | |
375 | LLVM_DEBUG(dbgs() << "endSection size=" << Size << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "endSection size=" << Size << "\n"; } } while (false); |
376 | |
377 | // Write the final section size to the payload_len field, which follows |
378 | // the section id byte. |
379 | uint8_t Buffer[16]; |
380 | unsigned SizeLen = encodeULEB128(Size, Buffer, 5); |
381 | assert(SizeLen == 5)((SizeLen == 5) ? static_cast<void> (0) : __assert_fail ("SizeLen == 5", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 381, __PRETTY_FUNCTION__)); |
382 | static_cast<raw_pwrite_stream &>(W.OS).pwrite((char *)Buffer, SizeLen, |
383 | Section.SizeOffset); |
384 | } |
385 | |
386 | // Emit the Wasm header. |
387 | void WasmObjectWriter::writeHeader(const MCAssembler &Asm) { |
388 | W.OS.write(wasm::WasmMagic, sizeof(wasm::WasmMagic)); |
389 | W.write<uint32_t>(wasm::WasmVersion); |
390 | } |
391 | |
392 | void WasmObjectWriter::executePostLayoutBinding(MCAssembler &Asm, |
393 | const MCAsmLayout &Layout) { |
394 | // Build a map of sections to the function that defines them, for use |
395 | // in recordRelocation. |
396 | for (const MCSymbol &S : Asm.symbols()) { |
397 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
398 | if (WS.isDefined() && WS.isFunction() && !WS.isVariable()) { |
399 | const auto &Sec = static_cast<const MCSectionWasm &>(S.getSection()); |
400 | auto Pair = SectionFunctions.insert(std::make_pair(&Sec, &S)); |
401 | if (!Pair.second) |
402 | report_fatal_error("section already has a defining function: " + |
403 | Sec.getSectionName()); |
404 | } |
405 | } |
406 | } |
407 | |
408 | void WasmObjectWriter::recordRelocation(MCAssembler &Asm, |
409 | const MCAsmLayout &Layout, |
410 | const MCFragment *Fragment, |
411 | const MCFixup &Fixup, MCValue Target, |
412 | uint64_t &FixedValue) { |
413 | MCAsmBackend &Backend = Asm.getBackend(); |
414 | bool IsPCRel = Backend.getFixupKindInfo(Fixup.getKind()).Flags & |
415 | MCFixupKindInfo::FKF_IsPCRel; |
416 | const auto &FixupSection = cast<MCSectionWasm>(*Fragment->getParent()); |
417 | uint64_t C = Target.getConstant(); |
418 | uint64_t FixupOffset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset(); |
419 | MCContext &Ctx = Asm.getContext(); |
420 | |
421 | // The .init_array isn't translated as data, so don't do relocations in it. |
422 | if (FixupSection.getSectionName().startswith(".init_array")) |
423 | return; |
424 | |
425 | if (const MCSymbolRefExpr *RefB = Target.getSymB()) { |
426 | 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-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 427, __PRETTY_FUNCTION__)) |
427 | "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-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 427, __PRETTY_FUNCTION__)); |
428 | |
429 | // Let A, B and C being the components of Target and R be the location of |
430 | // the fixup. If the fixup is not pcrel, we want to compute (A - B + C). |
431 | // If it is pcrel, we want to compute (A - B + C - R). |
432 | |
433 | // In general, Wasm has no relocations for -B. It can only represent (A + C) |
434 | // or (A + C - R). If B = R + K and the relocation is not pcrel, we can |
435 | // replace B to implement it: (A - R - K + C) |
436 | if (IsPCRel) { |
437 | Ctx.reportError( |
438 | Fixup.getLoc(), |
439 | "No relocation available to represent this relative expression"); |
440 | return; |
441 | } |
442 | |
443 | const auto &SymB = cast<MCSymbolWasm>(RefB->getSymbol()); |
444 | |
445 | if (SymB.isUndefined()) { |
446 | Ctx.reportError(Fixup.getLoc(), |
447 | Twine("symbol '") + SymB.getName() + |
448 | "' can not be undefined in a subtraction expression"); |
449 | return; |
450 | } |
451 | |
452 | 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-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 452, __PRETTY_FUNCTION__)); |
453 | const MCSection &SecB = SymB.getSection(); |
454 | if (&SecB != &FixupSection) { |
455 | Ctx.reportError(Fixup.getLoc(), |
456 | "Cannot represent a difference across sections"); |
457 | return; |
458 | } |
459 | |
460 | uint64_t SymBOffset = Layout.getSymbolOffset(SymB); |
461 | uint64_t K = SymBOffset - FixupOffset; |
462 | IsPCRel = true; |
463 | C -= K; |
464 | } |
465 | |
466 | // We either rejected the fixup or folded B into C at this point. |
467 | const MCSymbolRefExpr *RefA = Target.getSymA(); |
468 | const auto *SymA = RefA ? cast<MCSymbolWasm>(&RefA->getSymbol()) : nullptr; |
469 | |
470 | if (SymA && SymA->isVariable()) { |
471 | const MCExpr *Expr = SymA->getVariableValue(); |
472 | const auto *Inner = cast<MCSymbolRefExpr>(Expr); |
473 | if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF) |
474 | llvm_unreachable("weakref used in reloc not yet implemented")::llvm::llvm_unreachable_internal("weakref used in reloc not yet implemented" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 474); |
475 | } |
476 | |
477 | // Put any constant offset in an addend. Offsets can be negative, and |
478 | // LLVM expects wrapping, in contrast to wasm's immediates which can't |
479 | // be negative and don't wrap. |
480 | FixedValue = 0; |
481 | |
482 | unsigned Type = getRelocType(Target, Fixup); |
483 | assert(!IsPCRel)((!IsPCRel) ? static_cast<void> (0) : __assert_fail ("!IsPCRel" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 483, __PRETTY_FUNCTION__)); |
484 | assert(SymA)((SymA) ? static_cast<void> (0) : __assert_fail ("SymA" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 484, __PRETTY_FUNCTION__)); |
485 | |
486 | // Absolute offset within a section or a function. |
487 | // Currently only supported for for metadata sections. |
488 | // See: test/MC/WebAssembly/blockaddress.ll |
489 | if (Type == wasm::R_WEBASSEMBLY_FUNCTION_OFFSET_I32 || |
490 | Type == wasm::R_WEBASSEMBLY_SECTION_OFFSET_I32) { |
491 | if (!FixupSection.getKind().isMetadata()) |
492 | report_fatal_error("relocations for function or section offsets are " |
493 | "only supported in metadata sections"); |
494 | |
495 | const MCSymbol *SectionSymbol = nullptr; |
496 | const MCSection &SecA = SymA->getSection(); |
497 | if (SecA.getKind().isText()) |
498 | SectionSymbol = SectionFunctions.find(&SecA)->second; |
499 | else |
500 | SectionSymbol = SecA.getBeginSymbol(); |
501 | if (!SectionSymbol) |
502 | report_fatal_error("section symbol is required for relocation"); |
503 | |
504 | C += Layout.getSymbolOffset(*SymA); |
505 | SymA = cast<MCSymbolWasm>(SectionSymbol); |
506 | } |
507 | |
508 | // Relocation other than R_WEBASSEMBLY_TYPE_INDEX_LEB are required to be |
509 | // against a named symbol. |
510 | if (Type != wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB) { |
511 | if (SymA->getName().empty()) |
512 | report_fatal_error("relocations against un-named temporaries are not yet " |
513 | "supported by wasm"); |
514 | |
515 | SymA->setUsedInReloc(); |
516 | } |
517 | |
518 | WasmRelocationEntry Rec(FixupOffset, SymA, C, Type, &FixupSection); |
519 | LLVM_DEBUG(dbgs() << "WasmReloc: " << Rec << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "WasmReloc: " << Rec << "\n"; } } while (false); |
520 | |
521 | if (FixupSection.isWasmData()) { |
522 | DataRelocations.push_back(Rec); |
523 | } else if (FixupSection.getKind().isText()) { |
524 | CodeRelocations.push_back(Rec); |
525 | } else if (FixupSection.getKind().isMetadata()) { |
526 | CustomSectionsRelocations[&FixupSection].push_back(Rec); |
527 | } else { |
528 | llvm_unreachable("unexpected section type")::llvm::llvm_unreachable_internal("unexpected section type", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 528); |
529 | } |
530 | } |
531 | |
532 | // Write X as an (unsigned) LEB value at offset Offset in Stream, padded |
533 | // to allow patching. |
534 | static void WritePatchableLEB(raw_pwrite_stream &Stream, uint32_t X, |
535 | uint64_t Offset) { |
536 | uint8_t Buffer[5]; |
537 | unsigned SizeLen = encodeULEB128(X, Buffer, 5); |
538 | assert(SizeLen == 5)((SizeLen == 5) ? static_cast<void> (0) : __assert_fail ("SizeLen == 5", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 538, __PRETTY_FUNCTION__)); |
539 | Stream.pwrite((char *)Buffer, SizeLen, Offset); |
540 | } |
541 | |
542 | // Write X as an signed LEB value at offset Offset in Stream, padded |
543 | // to allow patching. |
544 | static void WritePatchableSLEB(raw_pwrite_stream &Stream, int32_t X, |
545 | uint64_t Offset) { |
546 | uint8_t Buffer[5]; |
547 | unsigned SizeLen = encodeSLEB128(X, Buffer, 5); |
548 | assert(SizeLen == 5)((SizeLen == 5) ? static_cast<void> (0) : __assert_fail ("SizeLen == 5", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 548, __PRETTY_FUNCTION__)); |
549 | Stream.pwrite((char *)Buffer, SizeLen, Offset); |
550 | } |
551 | |
552 | // Write X as a plain integer value at offset Offset in Stream. |
553 | static void WriteI32(raw_pwrite_stream &Stream, uint32_t X, uint64_t Offset) { |
554 | uint8_t Buffer[4]; |
555 | support::endian::write32le(Buffer, X); |
556 | Stream.pwrite((char *)Buffer, sizeof(Buffer), Offset); |
557 | } |
558 | |
559 | static const MCSymbolWasm *ResolveSymbol(const MCSymbolWasm &Symbol) { |
560 | if (Symbol.isVariable()) { |
561 | const MCExpr *Expr = Symbol.getVariableValue(); |
562 | auto *Inner = cast<MCSymbolRefExpr>(Expr); |
563 | return cast<MCSymbolWasm>(&Inner->getSymbol()); |
564 | } |
565 | return &Symbol; |
566 | } |
567 | |
568 | // Compute a value to write into the code at the location covered |
569 | // by RelEntry. This value isn't used by the static linker; it just serves |
570 | // to make the object format more readable and more likely to be directly |
571 | // useable. |
572 | uint32_t |
573 | WasmObjectWriter::getProvisionalValue(const WasmRelocationEntry &RelEntry) { |
574 | switch (RelEntry.Type) { |
575 | case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB: |
576 | case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32: { |
577 | // Provisional value is table address of the resolved symbol itself |
578 | const MCSymbolWasm *Sym = ResolveSymbol(*RelEntry.Symbol); |
579 | assert(Sym->isFunction())((Sym->isFunction()) ? static_cast<void> (0) : __assert_fail ("Sym->isFunction()", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 579, __PRETTY_FUNCTION__)); |
580 | return TableIndices[Sym]; |
581 | } |
582 | case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB: |
583 | // Provisional value is same as the index |
584 | return getRelocationIndexValue(RelEntry); |
585 | case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB: |
586 | case wasm::R_WEBASSEMBLY_GLOBAL_INDEX_LEB: |
587 | case wasm::R_WEBASSEMBLY_EVENT_INDEX_LEB: |
588 | // Provisional value is function/global/event Wasm index |
589 | if (!WasmIndices.count(RelEntry.Symbol)) |
590 | report_fatal_error("symbol not found in wasm index space: " + |
591 | RelEntry.Symbol->getName()); |
592 | return WasmIndices[RelEntry.Symbol]; |
593 | case wasm::R_WEBASSEMBLY_FUNCTION_OFFSET_I32: |
594 | case wasm::R_WEBASSEMBLY_SECTION_OFFSET_I32: { |
595 | const auto &Section = |
596 | static_cast<const MCSectionWasm &>(RelEntry.Symbol->getSection()); |
597 | return Section.getSectionOffset() + RelEntry.Addend; |
598 | } |
599 | case wasm::R_WEBASSEMBLY_MEMORY_ADDR_LEB: |
600 | case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32: |
601 | case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB: { |
602 | // Provisional value is address of the global |
603 | const MCSymbolWasm *Sym = ResolveSymbol(*RelEntry.Symbol); |
604 | // For undefined symbols, use zero |
605 | if (!Sym->isDefined()) |
606 | return 0; |
607 | const wasm::WasmDataReference &Ref = DataLocations[Sym]; |
608 | const WasmDataSegment &Segment = DataSegments[Ref.Segment]; |
609 | // Ignore overflow. LLVM allows address arithmetic to silently wrap. |
610 | return Segment.Offset + Ref.Offset + RelEntry.Addend; |
611 | } |
612 | default: |
613 | llvm_unreachable("invalid relocation type")::llvm::llvm_unreachable_internal("invalid relocation type", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 613); |
614 | } |
615 | } |
616 | |
617 | static void addData(SmallVectorImpl<char> &DataBytes, |
618 | MCSectionWasm &DataSection) { |
619 | LLVM_DEBUG(errs() << "addData: " << DataSection.getSectionName() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { errs() << "addData: " << DataSection.getSectionName () << "\n"; } } while (false); |
620 | |
621 | DataBytes.resize(alignTo(DataBytes.size(), DataSection.getAlignment())); |
622 | |
623 | for (const MCFragment &Frag : DataSection) { |
624 | if (Frag.hasInstructions()) |
625 | report_fatal_error("only data supported in data sections"); |
626 | |
627 | if (auto *Align = dyn_cast<MCAlignFragment>(&Frag)) { |
628 | if (Align->getValueSize() != 1) |
629 | report_fatal_error("only byte values supported for alignment"); |
630 | // If nops are requested, use zeros, as this is the data section. |
631 | uint8_t Value = Align->hasEmitNops() ? 0 : Align->getValue(); |
632 | uint64_t Size = |
633 | std::min<uint64_t>(alignTo(DataBytes.size(), Align->getAlignment()), |
634 | DataBytes.size() + Align->getMaxBytesToEmit()); |
635 | DataBytes.resize(Size, Value); |
636 | } else if (auto *Fill = dyn_cast<MCFillFragment>(&Frag)) { |
637 | int64_t NumValues; |
638 | if (!Fill->getNumValues().evaluateAsAbsolute(NumValues)) |
639 | llvm_unreachable("The fill should be an assembler constant")::llvm::llvm_unreachable_internal("The fill should be an assembler constant" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 639); |
640 | DataBytes.insert(DataBytes.end(), Fill->getValueSize() * NumValues, |
641 | Fill->getValue()); |
642 | } else if (auto *LEB = dyn_cast<MCLEBFragment>(&Frag)) { |
643 | const SmallVectorImpl<char> &Contents = LEB->getContents(); |
644 | DataBytes.insert(DataBytes.end(), Contents.begin(), Contents.end()); |
645 | } else { |
646 | const auto &DataFrag = cast<MCDataFragment>(Frag); |
647 | const SmallVectorImpl<char> &Contents = DataFrag.getContents(); |
648 | DataBytes.insert(DataBytes.end(), Contents.begin(), Contents.end()); |
649 | } |
650 | } |
651 | |
652 | LLVM_DEBUG(dbgs() << "addData -> " << DataBytes.size() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "addData -> " << DataBytes .size() << "\n"; } } while (false); |
653 | } |
654 | |
655 | uint32_t |
656 | WasmObjectWriter::getRelocationIndexValue(const WasmRelocationEntry &RelEntry) { |
657 | if (RelEntry.Type == wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB) { |
658 | if (!TypeIndices.count(RelEntry.Symbol)) |
659 | report_fatal_error("symbol not found in type index space: " + |
660 | RelEntry.Symbol->getName()); |
661 | return TypeIndices[RelEntry.Symbol]; |
662 | } |
663 | |
664 | return RelEntry.Symbol->getIndex(); |
665 | } |
666 | |
667 | // Apply the portions of the relocation records that we can handle ourselves |
668 | // directly. |
669 | void WasmObjectWriter::applyRelocations( |
670 | ArrayRef<WasmRelocationEntry> Relocations, uint64_t ContentsOffset) { |
671 | auto &Stream = static_cast<raw_pwrite_stream &>(W.OS); |
672 | for (const WasmRelocationEntry &RelEntry : Relocations) { |
673 | uint64_t Offset = ContentsOffset + |
674 | RelEntry.FixupSection->getSectionOffset() + |
675 | RelEntry.Offset; |
676 | |
677 | LLVM_DEBUG(dbgs() << "applyRelocation: " << RelEntry << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "applyRelocation: " << RelEntry << "\n"; } } while (false); |
678 | uint32_t Value = getProvisionalValue(RelEntry); |
679 | |
680 | switch (RelEntry.Type) { |
681 | case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB: |
682 | case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB: |
683 | case wasm::R_WEBASSEMBLY_GLOBAL_INDEX_LEB: |
684 | case wasm::R_WEBASSEMBLY_MEMORY_ADDR_LEB: |
685 | case wasm::R_WEBASSEMBLY_EVENT_INDEX_LEB: |
686 | WritePatchableLEB(Stream, Value, Offset); |
687 | break; |
688 | case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32: |
689 | case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32: |
690 | case wasm::R_WEBASSEMBLY_FUNCTION_OFFSET_I32: |
691 | case wasm::R_WEBASSEMBLY_SECTION_OFFSET_I32: |
692 | WriteI32(Stream, Value, Offset); |
693 | break; |
694 | case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB: |
695 | case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB: |
696 | WritePatchableSLEB(Stream, Value, Offset); |
697 | break; |
698 | default: |
699 | llvm_unreachable("invalid relocation type")::llvm::llvm_unreachable_internal("invalid relocation type", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 699); |
700 | } |
701 | } |
702 | } |
703 | |
704 | void WasmObjectWriter::writeTypeSection(ArrayRef<WasmSignature> Signatures) { |
705 | if (Signatures.empty()) |
706 | return; |
707 | |
708 | SectionBookkeeping Section; |
709 | startSection(Section, wasm::WASM_SEC_TYPE); |
710 | |
711 | encodeULEB128(Signatures.size(), W.OS); |
712 | |
713 | for (const WasmSignature &Sig : Signatures) { |
714 | W.OS << char(wasm::WASM_TYPE_FUNC); |
715 | encodeULEB128(Sig.Params.size(), W.OS); |
716 | for (wasm::ValType Ty : Sig.Params) |
717 | writeValueType(Ty); |
718 | encodeULEB128(Sig.Returns.size(), W.OS); |
719 | for (wasm::ValType Ty : Sig.Returns) |
720 | writeValueType(Ty); |
721 | } |
722 | |
723 | endSection(Section); |
724 | } |
725 | |
726 | void WasmObjectWriter::writeImportSection(ArrayRef<wasm::WasmImport> Imports, |
727 | uint32_t DataSize, |
728 | uint32_t NumElements) { |
729 | if (Imports.empty()) |
730 | return; |
731 | |
732 | uint32_t NumPages = (DataSize + wasm::WasmPageSize - 1) / wasm::WasmPageSize; |
733 | |
734 | SectionBookkeeping Section; |
735 | startSection(Section, wasm::WASM_SEC_IMPORT); |
736 | |
737 | encodeULEB128(Imports.size(), W.OS); |
738 | for (const wasm::WasmImport &Import : Imports) { |
739 | writeString(Import.Module); |
740 | writeString(Import.Field); |
741 | W.OS << char(Import.Kind); |
742 | |
743 | switch (Import.Kind) { |
744 | case wasm::WASM_EXTERNAL_FUNCTION: |
745 | encodeULEB128(Import.SigIndex, W.OS); |
746 | break; |
747 | case wasm::WASM_EXTERNAL_GLOBAL: |
748 | W.OS << char(Import.Global.Type); |
749 | W.OS << char(Import.Global.Mutable ? 1 : 0); |
750 | break; |
751 | case wasm::WASM_EXTERNAL_MEMORY: |
752 | encodeULEB128(0, W.OS); // flags |
753 | encodeULEB128(NumPages, W.OS); // initial |
754 | break; |
755 | case wasm::WASM_EXTERNAL_TABLE: |
756 | W.OS << char(Import.Table.ElemType); |
757 | encodeULEB128(0, W.OS); // flags |
758 | encodeULEB128(NumElements, W.OS); // initial |
759 | break; |
760 | case wasm::WASM_EXTERNAL_EVENT: |
761 | encodeULEB128(Import.Event.Attribute, W.OS); |
762 | encodeULEB128(Import.Event.SigIndex, W.OS); |
763 | break; |
764 | default: |
765 | llvm_unreachable("unsupported import kind")::llvm::llvm_unreachable_internal("unsupported import kind", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 765); |
766 | } |
767 | } |
768 | |
769 | endSection(Section); |
770 | } |
771 | |
772 | void WasmObjectWriter::writeFunctionSection(ArrayRef<WasmFunction> Functions) { |
773 | if (Functions.empty()) |
774 | return; |
775 | |
776 | SectionBookkeeping Section; |
777 | startSection(Section, wasm::WASM_SEC_FUNCTION); |
778 | |
779 | encodeULEB128(Functions.size(), W.OS); |
780 | for (const WasmFunction &Func : Functions) |
781 | encodeULEB128(Func.SigIndex, W.OS); |
782 | |
783 | endSection(Section); |
784 | } |
785 | |
786 | void WasmObjectWriter::writeGlobalSection() { |
787 | if (Globals.empty()) |
788 | return; |
789 | |
790 | SectionBookkeeping Section; |
791 | startSection(Section, wasm::WASM_SEC_GLOBAL); |
792 | |
793 | encodeULEB128(Globals.size(), W.OS); |
794 | for (const WasmGlobal &Global : Globals) { |
795 | writeValueType(static_cast<wasm::ValType>(Global.Type.Type)); |
796 | W.OS << char(Global.Type.Mutable); |
797 | |
798 | W.OS << char(wasm::WASM_OPCODE_I32_CONST); |
799 | encodeSLEB128(Global.InitialValue, W.OS); |
800 | W.OS << char(wasm::WASM_OPCODE_END); |
801 | } |
802 | |
803 | endSection(Section); |
804 | } |
805 | |
806 | void WasmObjectWriter::writeEventSection(ArrayRef<wasm::WasmEventType> Events) { |
807 | if (Events.empty()) |
808 | return; |
809 | |
810 | SectionBookkeeping Section; |
811 | startSection(Section, wasm::WASM_SEC_EVENT); |
812 | |
813 | encodeULEB128(Events.size(), W.OS); |
814 | for (const wasm::WasmEventType &Event : Events) { |
815 | encodeULEB128(Event.Attribute, W.OS); |
816 | encodeULEB128(Event.SigIndex, W.OS); |
817 | } |
818 | |
819 | endSection(Section); |
820 | } |
821 | |
822 | void WasmObjectWriter::writeExportSection(ArrayRef<wasm::WasmExport> Exports) { |
823 | if (Exports.empty()) |
824 | return; |
825 | |
826 | SectionBookkeeping Section; |
827 | startSection(Section, wasm::WASM_SEC_EXPORT); |
828 | |
829 | encodeULEB128(Exports.size(), W.OS); |
830 | for (const wasm::WasmExport &Export : Exports) { |
831 | writeString(Export.Name); |
832 | W.OS << char(Export.Kind); |
833 | encodeULEB128(Export.Index, W.OS); |
834 | } |
835 | |
836 | endSection(Section); |
837 | } |
838 | |
839 | void WasmObjectWriter::writeElemSection(ArrayRef<uint32_t> TableElems) { |
840 | if (TableElems.empty()) |
841 | return; |
842 | |
843 | SectionBookkeeping Section; |
844 | startSection(Section, wasm::WASM_SEC_ELEM); |
845 | |
846 | encodeULEB128(1, W.OS); // number of "segments" |
847 | encodeULEB128(0, W.OS); // the table index |
848 | |
849 | // init expr for starting offset |
850 | W.OS << char(wasm::WASM_OPCODE_I32_CONST); |
851 | encodeSLEB128(kInitialTableOffset, W.OS); |
852 | W.OS << char(wasm::WASM_OPCODE_END); |
853 | |
854 | encodeULEB128(TableElems.size(), W.OS); |
855 | for (uint32_t Elem : TableElems) |
856 | encodeULEB128(Elem, W.OS); |
857 | |
858 | endSection(Section); |
859 | } |
860 | |
861 | void WasmObjectWriter::writeCodeSection(const MCAssembler &Asm, |
862 | const MCAsmLayout &Layout, |
863 | ArrayRef<WasmFunction> Functions) { |
864 | if (Functions.empty()) |
865 | return; |
866 | |
867 | SectionBookkeeping Section; |
868 | startSection(Section, wasm::WASM_SEC_CODE); |
869 | CodeSectionIndex = Section.Index; |
870 | |
871 | encodeULEB128(Functions.size(), W.OS); |
872 | |
873 | for (const WasmFunction &Func : Functions) { |
874 | auto &FuncSection = static_cast<MCSectionWasm &>(Func.Sym->getSection()); |
875 | |
876 | int64_t Size = 0; |
877 | if (!Func.Sym->getSize()->evaluateAsAbsolute(Size, Layout)) |
878 | report_fatal_error(".size expression must be evaluatable"); |
879 | |
880 | encodeULEB128(Size, W.OS); |
881 | FuncSection.setSectionOffset(W.OS.tell() - Section.ContentsOffset); |
882 | Asm.writeSectionData(W.OS, &FuncSection, Layout); |
883 | } |
884 | |
885 | // Apply fixups. |
886 | applyRelocations(CodeRelocations, Section.ContentsOffset); |
887 | |
888 | endSection(Section); |
889 | } |
890 | |
891 | void WasmObjectWriter::writeDataSection() { |
892 | if (DataSegments.empty()) |
893 | return; |
894 | |
895 | SectionBookkeeping Section; |
896 | startSection(Section, wasm::WASM_SEC_DATA); |
897 | DataSectionIndex = Section.Index; |
898 | |
899 | encodeULEB128(DataSegments.size(), W.OS); // count |
900 | |
901 | for (const WasmDataSegment &Segment : DataSegments) { |
902 | encodeULEB128(0, W.OS); // memory index |
903 | W.OS << char(wasm::WASM_OPCODE_I32_CONST); |
904 | encodeSLEB128(Segment.Offset, W.OS); // offset |
905 | W.OS << char(wasm::WASM_OPCODE_END); |
906 | encodeULEB128(Segment.Data.size(), W.OS); // size |
907 | Segment.Section->setSectionOffset(W.OS.tell() - Section.ContentsOffset); |
908 | W.OS << Segment.Data; // data |
909 | } |
910 | |
911 | // Apply fixups. |
912 | applyRelocations(DataRelocations, Section.ContentsOffset); |
913 | |
914 | endSection(Section); |
915 | } |
916 | |
917 | void WasmObjectWriter::writeRelocSection( |
918 | uint32_t SectionIndex, StringRef Name, |
919 | std::vector<WasmRelocationEntry> &Relocs) { |
920 | // See: https://github.com/WebAssembly/tool-conventions/blob/master/Linking.md |
921 | // for descriptions of the reloc sections. |
922 | |
923 | if (Relocs.empty()) |
924 | return; |
925 | |
926 | // First, ensure the relocations are sorted in offset order. In general they |
927 | // should already be sorted since `recordRelocation` is called in offset |
928 | // order, but for the code section we combine many MC sections into single |
929 | // wasm section, and this order is determined by the order of Asm.Symbols() |
930 | // not the sections order. |
931 | std::stable_sort( |
932 | Relocs.begin(), Relocs.end(), |
933 | [](const WasmRelocationEntry &A, const WasmRelocationEntry &B) { |
934 | return (A.Offset + A.FixupSection->getSectionOffset()) < |
935 | (B.Offset + B.FixupSection->getSectionOffset()); |
936 | }); |
937 | |
938 | SectionBookkeeping Section; |
939 | startCustomSection(Section, std::string("reloc.") + Name.str()); |
940 | |
941 | encodeULEB128(SectionIndex, W.OS); |
942 | encodeULEB128(Relocs.size(), W.OS); |
943 | for (const WasmRelocationEntry &RelEntry : Relocs) { |
944 | uint64_t Offset = |
945 | RelEntry.Offset + RelEntry.FixupSection->getSectionOffset(); |
946 | uint32_t Index = getRelocationIndexValue(RelEntry); |
947 | |
948 | W.OS << char(RelEntry.Type); |
949 | encodeULEB128(Offset, W.OS); |
950 | encodeULEB128(Index, W.OS); |
951 | if (RelEntry.hasAddend()) |
952 | encodeSLEB128(RelEntry.Addend, W.OS); |
953 | } |
954 | |
955 | endSection(Section); |
956 | } |
957 | |
958 | void WasmObjectWriter::writeCustomRelocSections() { |
959 | for (const auto &Sec : CustomSections) { |
960 | auto &Relocations = CustomSectionsRelocations[Sec.Section]; |
961 | writeRelocSection(Sec.OutputIndex, Sec.Name, Relocations); |
962 | } |
963 | } |
964 | |
965 | void WasmObjectWriter::writeLinkingMetaDataSection( |
966 | ArrayRef<wasm::WasmSymbolInfo> SymbolInfos, |
967 | ArrayRef<std::pair<uint16_t, uint32_t>> InitFuncs, |
968 | const std::map<StringRef, std::vector<WasmComdatEntry>> &Comdats) { |
969 | SectionBookkeeping Section; |
970 | startCustomSection(Section, "linking"); |
971 | encodeULEB128(wasm::WasmMetadataVersion, W.OS); |
972 | |
973 | SectionBookkeeping SubSection; |
974 | if (SymbolInfos.size() != 0) { |
975 | startSection(SubSection, wasm::WASM_SYMBOL_TABLE); |
976 | encodeULEB128(SymbolInfos.size(), W.OS); |
977 | for (const wasm::WasmSymbolInfo &Sym : SymbolInfos) { |
978 | encodeULEB128(Sym.Kind, W.OS); |
979 | encodeULEB128(Sym.Flags, W.OS); |
980 | switch (Sym.Kind) { |
981 | case wasm::WASM_SYMBOL_TYPE_FUNCTION: |
982 | case wasm::WASM_SYMBOL_TYPE_GLOBAL: |
983 | case wasm::WASM_SYMBOL_TYPE_EVENT: |
984 | encodeULEB128(Sym.ElementIndex, W.OS); |
985 | if ((Sym.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0) |
986 | writeString(Sym.Name); |
987 | break; |
988 | case wasm::WASM_SYMBOL_TYPE_DATA: |
989 | writeString(Sym.Name); |
990 | if ((Sym.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0) { |
991 | encodeULEB128(Sym.DataRef.Segment, W.OS); |
992 | encodeULEB128(Sym.DataRef.Offset, W.OS); |
993 | encodeULEB128(Sym.DataRef.Size, W.OS); |
994 | } |
995 | break; |
996 | case wasm::WASM_SYMBOL_TYPE_SECTION: { |
997 | const uint32_t SectionIndex = |
998 | CustomSections[Sym.ElementIndex].OutputIndex; |
999 | encodeULEB128(SectionIndex, W.OS); |
1000 | break; |
1001 | } |
1002 | default: |
1003 | llvm_unreachable("unexpected kind")::llvm::llvm_unreachable_internal("unexpected kind", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1003); |
1004 | } |
1005 | } |
1006 | endSection(SubSection); |
1007 | } |
1008 | |
1009 | if (DataSegments.size()) { |
1010 | startSection(SubSection, wasm::WASM_SEGMENT_INFO); |
1011 | encodeULEB128(DataSegments.size(), W.OS); |
1012 | for (const WasmDataSegment &Segment : DataSegments) { |
1013 | writeString(Segment.Name); |
1014 | encodeULEB128(Segment.Alignment, W.OS); |
1015 | encodeULEB128(Segment.Flags, W.OS); |
1016 | } |
1017 | endSection(SubSection); |
1018 | } |
1019 | |
1020 | if (!InitFuncs.empty()) { |
1021 | startSection(SubSection, wasm::WASM_INIT_FUNCS); |
1022 | encodeULEB128(InitFuncs.size(), W.OS); |
1023 | for (auto &StartFunc : InitFuncs) { |
1024 | encodeULEB128(StartFunc.first, W.OS); // priority |
1025 | encodeULEB128(StartFunc.second, W.OS); // function index |
1026 | } |
1027 | endSection(SubSection); |
1028 | } |
1029 | |
1030 | if (Comdats.size()) { |
1031 | startSection(SubSection, wasm::WASM_COMDAT_INFO); |
1032 | encodeULEB128(Comdats.size(), W.OS); |
1033 | for (const auto &C : Comdats) { |
1034 | writeString(C.first); |
1035 | encodeULEB128(0, W.OS); // flags for future use |
1036 | encodeULEB128(C.second.size(), W.OS); |
1037 | for (const WasmComdatEntry &Entry : C.second) { |
1038 | encodeULEB128(Entry.Kind, W.OS); |
1039 | encodeULEB128(Entry.Index, W.OS); |
1040 | } |
1041 | } |
1042 | endSection(SubSection); |
1043 | } |
1044 | |
1045 | endSection(Section); |
1046 | } |
1047 | |
1048 | void WasmObjectWriter::writeCustomSections(const MCAssembler &Asm, |
1049 | const MCAsmLayout &Layout) { |
1050 | for (auto &CustomSection : CustomSections) { |
1051 | SectionBookkeeping Section; |
1052 | auto *Sec = CustomSection.Section; |
1053 | startCustomSection(Section, CustomSection.Name); |
1054 | |
1055 | Sec->setSectionOffset(W.OS.tell() - Section.ContentsOffset); |
1056 | Asm.writeSectionData(W.OS, Sec, Layout); |
1057 | |
1058 | CustomSection.OutputContentsOffset = Section.ContentsOffset; |
1059 | CustomSection.OutputIndex = Section.Index; |
1060 | |
1061 | endSection(Section); |
1062 | |
1063 | // Apply fixups. |
1064 | auto &Relocations = CustomSectionsRelocations[CustomSection.Section]; |
1065 | applyRelocations(Relocations, CustomSection.OutputContentsOffset); |
1066 | } |
1067 | } |
1068 | |
1069 | uint32_t WasmObjectWriter::getFunctionType(const MCSymbolWasm &Symbol) { |
1070 | assert(Symbol.isFunction())((Symbol.isFunction()) ? static_cast<void> (0) : __assert_fail ("Symbol.isFunction()", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1070, __PRETTY_FUNCTION__)); |
1071 | assert(TypeIndices.count(&Symbol))((TypeIndices.count(&Symbol)) ? static_cast<void> ( 0) : __assert_fail ("TypeIndices.count(&Symbol)", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1071, __PRETTY_FUNCTION__)); |
1072 | return TypeIndices[&Symbol]; |
1073 | } |
1074 | |
1075 | uint32_t WasmObjectWriter::getEventType(const MCSymbolWasm &Symbol) { |
1076 | assert(Symbol.isEvent())((Symbol.isEvent()) ? static_cast<void> (0) : __assert_fail ("Symbol.isEvent()", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1076, __PRETTY_FUNCTION__)); |
1077 | assert(TypeIndices.count(&Symbol))((TypeIndices.count(&Symbol)) ? static_cast<void> ( 0) : __assert_fail ("TypeIndices.count(&Symbol)", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1077, __PRETTY_FUNCTION__)); |
1078 | return TypeIndices[&Symbol]; |
1079 | } |
1080 | |
1081 | void WasmObjectWriter::registerFunctionType(const MCSymbolWasm &Symbol) { |
1082 | assert(Symbol.isFunction())((Symbol.isFunction()) ? static_cast<void> (0) : __assert_fail ("Symbol.isFunction()", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1082, __PRETTY_FUNCTION__)); |
1083 | |
1084 | WasmSignature S; |
1085 | const MCSymbolWasm *ResolvedSym = ResolveSymbol(Symbol); |
1086 | if (auto *Sig = ResolvedSym->getSignature()) { |
1087 | S.Returns = Sig->Returns; |
1088 | S.Params = Sig->Params; |
1089 | } |
1090 | |
1091 | auto Pair = SignatureIndices.insert(std::make_pair(S, Signatures.size())); |
1092 | if (Pair.second) |
1093 | Signatures.push_back(S); |
1094 | TypeIndices[&Symbol] = Pair.first->second; |
1095 | |
1096 | LLVM_DEBUG(dbgs() << "registerFunctionType: " << Symboldo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "registerFunctionType: " << Symbol << " new:" << Pair.second << "\n"; } } while (false) |
1097 | << " new:" << Pair.second << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "registerFunctionType: " << Symbol << " new:" << Pair.second << "\n"; } } while (false); |
1098 | 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); |
1099 | } |
1100 | |
1101 | void WasmObjectWriter::registerEventType(const MCSymbolWasm &Symbol) { |
1102 | assert(Symbol.isEvent())((Symbol.isEvent()) ? static_cast<void> (0) : __assert_fail ("Symbol.isEvent()", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1102, __PRETTY_FUNCTION__)); |
1103 | |
1104 | // TODO Currently we don't generate imported exceptions, but if we do, we |
1105 | // should have a way of infering types of imported exceptions. |
1106 | WasmSignature S; |
1107 | if (auto *Sig = Symbol.getSignature()) { |
1108 | S.Returns = Sig->Returns; |
1109 | S.Params = Sig->Params; |
1110 | } |
1111 | |
1112 | auto Pair = SignatureIndices.insert(std::make_pair(S, Signatures.size())); |
1113 | if (Pair.second) |
1114 | Signatures.push_back(S); |
1115 | TypeIndices[&Symbol] = Pair.first->second; |
1116 | |
1117 | LLVM_DEBUG(dbgs() << "registerEventType: " << Symbol << " new:" << Pair.seconddo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "registerEventType: " << Symbol << " new:" << Pair.second << "\n"; } } while (false) |
1118 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "registerEventType: " << Symbol << " new:" << Pair.second << "\n"; } } while (false); |
1119 | 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); |
1120 | } |
1121 | |
1122 | static bool isInSymtab(const MCSymbolWasm &Sym) { |
1123 | if (Sym.isUsedInReloc()) |
1124 | return true; |
1125 | |
1126 | if (Sym.isComdat() && !Sym.isDefined()) |
1127 | return false; |
1128 | |
1129 | if (Sym.isTemporary() && Sym.getName().empty()) |
1130 | return false; |
1131 | |
1132 | if (Sym.isTemporary() && Sym.isData() && !Sym.getSize()) |
1133 | return false; |
1134 | |
1135 | if (Sym.isSection()) |
1136 | return false; |
1137 | |
1138 | return true; |
1139 | } |
1140 | |
1141 | uint64_t WasmObjectWriter::writeObject(MCAssembler &Asm, |
1142 | const MCAsmLayout &Layout) { |
1143 | uint64_t StartOffset = W.OS.tell(); |
1144 | |
1145 | LLVM_DEBUG(dbgs() << "WasmObjectWriter::writeObject\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "WasmObjectWriter::writeObject\n"; } } while (false); |
1146 | MCContext &Ctx = Asm.getContext(); |
1147 | |
1148 | // Collect information from the available symbols. |
1149 | SmallVector<WasmFunction, 4> Functions; |
1150 | SmallVector<uint32_t, 4> TableElems; |
1151 | SmallVector<wasm::WasmImport, 4> Imports; |
1152 | SmallVector<wasm::WasmExport, 4> Exports; |
1153 | SmallVector<wasm::WasmEventType, 1> Events; |
1154 | SmallVector<wasm::WasmSymbolInfo, 4> SymbolInfos; |
1155 | SmallVector<std::pair<uint16_t, uint32_t>, 2> InitFuncs; |
1156 | std::map<StringRef, std::vector<WasmComdatEntry>> Comdats; |
1157 | uint32_t DataSize = 0; |
1158 | |
1159 | // For now, always emit the memory import, since loads and stores are not |
1160 | // valid without it. In the future, we could perhaps be more clever and omit |
1161 | // it if there are no loads or stores. |
1162 | MCSymbolWasm *MemorySym = |
1163 | cast<MCSymbolWasm>(Ctx.getOrCreateSymbol("__linear_memory")); |
1164 | wasm::WasmImport MemImport; |
1165 | MemImport.Module = MemorySym->getModuleName(); |
1166 | MemImport.Field = MemorySym->getName(); |
1167 | MemImport.Kind = wasm::WASM_EXTERNAL_MEMORY; |
1168 | Imports.push_back(MemImport); |
1169 | |
1170 | // For now, always emit the table section, since indirect calls are not |
1171 | // valid without it. In the future, we could perhaps be more clever and omit |
1172 | // it if there are no indirect calls. |
1173 | MCSymbolWasm *TableSym = |
1174 | cast<MCSymbolWasm>(Ctx.getOrCreateSymbol("__indirect_function_table")); |
1175 | wasm::WasmImport TableImport; |
1176 | TableImport.Module = TableSym->getModuleName(); |
1177 | TableImport.Field = TableSym->getName(); |
1178 | TableImport.Kind = wasm::WASM_EXTERNAL_TABLE; |
1179 | TableImport.Table.ElemType = wasm::WASM_TYPE_ANYFUNC; |
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.getModuleName(); |
1204 | Import.Field = WS.getName(); |
1205 | Import.Kind = wasm::WASM_EXTERNAL_FUNCTION; |
1206 | Import.SigIndex = getFunctionType(WS); |
1207 | Imports.push_back(Import); |
1208 | WasmIndices[&WS] = NumFunctionImports++; |
1209 | } else if (WS.isGlobal()) { |
1210 | if (WS.isWeak()) |
1211 | report_fatal_error("undefined global symbol cannot be weak"); |
1212 | |
1213 | wasm::WasmImport Import; |
1214 | Import.Module = WS.getModuleName(); |
1215 | Import.Field = WS.getName(); |
1216 | Import.Kind = wasm::WASM_EXTERNAL_GLOBAL; |
1217 | Import.Global = WS.getGlobalType(); |
1218 | Imports.push_back(Import); |
1219 | WasmIndices[&WS] = NumGlobalImports++; |
1220 | } else if (WS.isEvent()) { |
1221 | if (WS.isWeak()) |
1222 | report_fatal_error("undefined event symbol cannot be weak"); |
1223 | |
1224 | wasm::WasmImport Import; |
1225 | Import.Module = WS.getModuleName(); |
1226 | Import.Field = WS.getName(); |
1227 | Import.Kind = wasm::WASM_EXTERNAL_EVENT; |
1228 | Import.Event.Attribute = wasm::WASM_EVENT_ATTRIBUTE_EXCEPTION; |
1229 | Import.Event.SigIndex = getEventType(WS); |
1230 | Imports.push_back(Import); |
1231 | WasmIndices[&WS] = NumEventImports++; |
1232 | } |
1233 | } |
1234 | } |
1235 | |
1236 | // Populate DataSegments and CustomSections, which must be done before |
1237 | // populating DataLocations. |
1238 | for (MCSection &Sec : Asm) { |
1239 | auto &Section = static_cast<MCSectionWasm &>(Sec); |
1240 | StringRef SectionName = Section.getSectionName(); |
1241 | |
1242 | // .init_array sections are handled specially elsewhere. |
1243 | if (SectionName.startswith(".init_array")) |
1244 | continue; |
1245 | |
1246 | // Code is handled separately |
1247 | if (Section.getKind().isText()) |
1248 | continue; |
1249 | |
1250 | if (Section.isWasmData()) { |
1251 | uint32_t SegmentIndex = DataSegments.size(); |
1252 | DataSize = alignTo(DataSize, Section.getAlignment()); |
1253 | DataSegments.emplace_back(); |
1254 | WasmDataSegment &Segment = DataSegments.back(); |
1255 | Segment.Name = SectionName; |
1256 | Segment.Offset = DataSize; |
1257 | Segment.Section = &Section; |
1258 | addData(Segment.Data, Section); |
1259 | Segment.Alignment = Section.getAlignment(); |
1260 | Segment.Flags = 0; |
1261 | DataSize += Segment.Data.size(); |
1262 | Section.setSegmentIndex(SegmentIndex); |
1263 | |
1264 | if (const MCSymbolWasm *C = Section.getGroup()) { |
1265 | Comdats[C->getName()].emplace_back( |
1266 | WasmComdatEntry{wasm::WASM_COMDAT_DATA, SegmentIndex}); |
1267 | } |
1268 | } else { |
1269 | // Create custom sections |
1270 | assert(Sec.getKind().isMetadata())((Sec.getKind().isMetadata()) ? static_cast<void> (0) : __assert_fail ("Sec.getKind().isMetadata()", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1270, __PRETTY_FUNCTION__)); |
1271 | |
1272 | StringRef Name = SectionName; |
1273 | |
1274 | // For user-defined custom sections, strip the prefix |
1275 | if (Name.startswith(".custom_section.")) |
1276 | Name = Name.substr(strlen(".custom_section.")); |
1277 | |
1278 | MCSymbol *Begin = Sec.getBeginSymbol(); |
1279 | if (Begin) { |
1280 | WasmIndices[cast<MCSymbolWasm>(Begin)] = CustomSections.size(); |
1281 | if (SectionName != Begin->getName()) |
1282 | report_fatal_error("section name and begin symbol should match: " + |
1283 | Twine(SectionName)); |
1284 | } |
1285 | CustomSections.emplace_back(Name, &Section); |
1286 | } |
1287 | } |
1288 | |
1289 | // Populate WasmIndices and DataLocations for defined symbols. |
1290 | for (const MCSymbol &S : Asm.symbols()) { |
1291 | // Ignore unnamed temporary symbols, which aren't ever exported, imported, |
1292 | // or used in relocations. |
1293 | if (S.isTemporary() && S.getName().empty()) |
1294 | continue; |
1295 | |
1296 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
1297 | 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) |
1298 | 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) |
1299 | << " 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) |
1300 | << 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) |
1301 | << " 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) |
1302 | << " 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); |
1303 | |
1304 | if (WS.isVariable()) |
1305 | continue; |
1306 | if (WS.isComdat() && !WS.isDefined()) |
1307 | continue; |
1308 | |
1309 | if (WS.isFunction()) { |
1310 | unsigned Index; |
1311 | if (WS.isDefined()) { |
1312 | if (WS.getOffset() != 0) |
1313 | report_fatal_error( |
1314 | "function sections must contain one function each"); |
1315 | |
1316 | if (WS.getSize() == 0) |
1317 | report_fatal_error( |
1318 | "function symbols must have a size set with .size"); |
1319 | |
1320 | // A definition. Write out the function body. |
1321 | Index = NumFunctionImports + Functions.size(); |
1322 | WasmFunction Func; |
1323 | Func.SigIndex = getFunctionType(WS); |
1324 | Func.Sym = &WS; |
1325 | WasmIndices[&WS] = Index; |
1326 | Functions.push_back(Func); |
1327 | |
1328 | auto &Section = static_cast<MCSectionWasm &>(WS.getSection()); |
1329 | if (const MCSymbolWasm *C = Section.getGroup()) { |
1330 | Comdats[C->getName()].emplace_back( |
1331 | WasmComdatEntry{wasm::WASM_COMDAT_FUNCTION, Index}); |
1332 | } |
1333 | } else { |
1334 | // An import; the index was assigned above. |
1335 | Index = WasmIndices.find(&WS)->second; |
1336 | } |
1337 | |
1338 | LLVM_DEBUG(dbgs() << " -> function index: " << Index << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> function index: " << Index << "\n"; } } while (false); |
1339 | |
1340 | } else if (WS.isData()) { |
1341 | if (WS.isTemporary() && !WS.getSize()) |
1342 | continue; |
1343 | |
1344 | if (!WS.isDefined()) { |
1345 | LLVM_DEBUG(dbgs() << " -> segment index: -1"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> segment index: -1" << "\n"; } } while (false) |
1346 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> segment index: -1" << "\n"; } } while (false); |
1347 | continue; |
1348 | } |
1349 | |
1350 | if (!WS.getSize()) |
1351 | report_fatal_error("data symbols must have a size set with .size: " + |
1352 | WS.getName()); |
1353 | |
1354 | int64_t Size = 0; |
1355 | if (!WS.getSize()->evaluateAsAbsolute(Size, Layout)) |
1356 | report_fatal_error(".size expression must be evaluatable"); |
1357 | |
1358 | auto &DataSection = static_cast<MCSectionWasm &>(WS.getSection()); |
1359 | assert(DataSection.isWasmData())((DataSection.isWasmData()) ? static_cast<void> (0) : __assert_fail ("DataSection.isWasmData()", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1359, __PRETTY_FUNCTION__)); |
1360 | |
1361 | // For each data symbol, export it in the symtab as a reference to the |
1362 | // corresponding Wasm data segment. |
1363 | wasm::WasmDataReference Ref = wasm::WasmDataReference{ |
1364 | DataSection.getSegmentIndex(), |
1365 | static_cast<uint32_t>(Layout.getSymbolOffset(WS)), |
1366 | static_cast<uint32_t>(Size)}; |
1367 | DataLocations[&WS] = Ref; |
1368 | LLVM_DEBUG(dbgs() << " -> segment index: " << Ref.Segment << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> segment index: " << Ref .Segment << "\n"; } } while (false); |
1369 | |
1370 | } else if (WS.isGlobal()) { |
1371 | // A "true" Wasm global (currently just __stack_pointer) |
1372 | if (WS.isDefined()) |
1373 | report_fatal_error("don't yet support defined globals"); |
1374 | |
1375 | // An import; the index was assigned above |
1376 | LLVM_DEBUG(dbgs() << " -> global index: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> global index: " << WasmIndices .find(&WS)->second << "\n"; } } while (false) |
1377 | << WasmIndices.find(&WS)->second << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> global index: " << WasmIndices .find(&WS)->second << "\n"; } } while (false); |
1378 | |
1379 | } else if (WS.isEvent()) { |
1380 | // C++ exception symbol (__cpp_exception) |
1381 | unsigned Index; |
1382 | if (WS.isDefined()) { |
1383 | Index = NumEventImports + Events.size(); |
1384 | wasm::WasmEventType Event; |
1385 | Event.SigIndex = getEventType(WS); |
1386 | Event.Attribute = wasm::WASM_EVENT_ATTRIBUTE_EXCEPTION; |
1387 | WasmIndices[&WS] = Index; |
1388 | Events.push_back(Event); |
1389 | } else { |
1390 | // An import; the index was assigned above. |
1391 | Index = WasmIndices.find(&WS)->second; |
Value stored to 'Index' is never read | |
1392 | } |
1393 | 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) |
1394 | << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> event index: " << WasmIndices .find(&WS)->second << "\n"; } } while (false); |
1395 | |
1396 | } else { |
1397 | assert(WS.isSection())((WS.isSection()) ? static_cast<void> (0) : __assert_fail ("WS.isSection()", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1397, __PRETTY_FUNCTION__)); |
1398 | } |
1399 | } |
1400 | |
1401 | // Populate WasmIndices and DataLocations for aliased symbols. We need to |
1402 | // process these in a separate pass because we need to have processed the |
1403 | // target of the alias before the alias itself and the symbols are not |
1404 | // necessarily ordered in this way. |
1405 | for (const MCSymbol &S : Asm.symbols()) { |
1406 | if (!S.isVariable()) |
1407 | continue; |
1408 | |
1409 | assert(S.isDefined())((S.isDefined()) ? static_cast<void> (0) : __assert_fail ("S.isDefined()", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1409, __PRETTY_FUNCTION__)); |
1410 | |
1411 | // Find the target symbol of this weak alias and export that index |
1412 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
1413 | const MCSymbolWasm *ResolvedSym = ResolveSymbol(WS); |
1414 | 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) |
1415 | << "'\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << WS.getName() << ": weak alias of '" << *ResolvedSym << "'\n"; } } while (false); |
1416 | |
1417 | if (WS.isFunction()) { |
1418 | assert(WasmIndices.count(ResolvedSym) > 0)((WasmIndices.count(ResolvedSym) > 0) ? static_cast<void > (0) : __assert_fail ("WasmIndices.count(ResolvedSym) > 0" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1418, __PRETTY_FUNCTION__)); |
1419 | uint32_t WasmIndex = WasmIndices.find(ResolvedSym)->second; |
1420 | WasmIndices[&WS] = WasmIndex; |
1421 | LLVM_DEBUG(dbgs() << " -> index:" << WasmIndex << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> index:" << WasmIndex << "\n"; } } while (false); |
1422 | } else if (WS.isData()) { |
1423 | assert(DataLocations.count(ResolvedSym) > 0)((DataLocations.count(ResolvedSym) > 0) ? static_cast<void > (0) : __assert_fail ("DataLocations.count(ResolvedSym) > 0" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1423, __PRETTY_FUNCTION__)); |
1424 | const wasm::WasmDataReference &Ref = |
1425 | DataLocations.find(ResolvedSym)->second; |
1426 | DataLocations[&WS] = Ref; |
1427 | LLVM_DEBUG(dbgs() << " -> index:" << Ref.Segment << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> index:" << Ref.Segment << "\n"; } } while (false); |
1428 | } else { |
1429 | report_fatal_error("don't yet support global/event aliases"); |
1430 | } |
1431 | } |
1432 | |
1433 | // Finally, populate the symbol table itself, in its "natural" order. |
1434 | for (const MCSymbol &S : Asm.symbols()) { |
1435 | const auto &WS = static_cast<const MCSymbolWasm &>(S); |
1436 | if (!isInSymtab(WS)) { |
1437 | WS.setIndex(INVALID_INDEX); |
1438 | continue; |
1439 | } |
1440 | LLVM_DEBUG(dbgs() << "adding to symtab: " << WS << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << "adding to symtab: " << WS << "\n"; } } while (false); |
1441 | |
1442 | uint32_t Flags = 0; |
1443 | if (WS.isWeak()) |
1444 | Flags |= wasm::WASM_SYMBOL_BINDING_WEAK; |
1445 | if (WS.isHidden()) |
1446 | Flags |= wasm::WASM_SYMBOL_VISIBILITY_HIDDEN; |
1447 | if (!WS.isExternal() && WS.isDefined()) |
1448 | Flags |= wasm::WASM_SYMBOL_BINDING_LOCAL; |
1449 | if (WS.isUndefined()) |
1450 | Flags |= wasm::WASM_SYMBOL_UNDEFINED; |
1451 | |
1452 | wasm::WasmSymbolInfo Info; |
1453 | Info.Name = WS.getName(); |
1454 | Info.Kind = WS.getType(); |
1455 | Info.Flags = Flags; |
1456 | if (!WS.isData()) { |
1457 | assert(WasmIndices.count(&WS) > 0)((WasmIndices.count(&WS) > 0) ? static_cast<void> (0) : __assert_fail ("WasmIndices.count(&WS) > 0", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1457, __PRETTY_FUNCTION__)); |
1458 | Info.ElementIndex = WasmIndices.find(&WS)->second; |
1459 | } else if (WS.isDefined()) { |
1460 | assert(DataLocations.count(&WS) > 0)((DataLocations.count(&WS) > 0) ? static_cast<void> (0) : __assert_fail ("DataLocations.count(&WS) > 0", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1460, __PRETTY_FUNCTION__)); |
1461 | Info.DataRef = DataLocations.find(&WS)->second; |
1462 | } |
1463 | WS.setIndex(SymbolInfos.size()); |
1464 | SymbolInfos.emplace_back(Info); |
1465 | } |
1466 | |
1467 | { |
1468 | auto HandleReloc = [&](const WasmRelocationEntry &Rel) { |
1469 | // Functions referenced by a relocation need to put in the table. This is |
1470 | // purely to make the object file's provisional values readable, and is |
1471 | // ignored by the linker, which re-calculates the relocations itself. |
1472 | if (Rel.Type != wasm::R_WEBASSEMBLY_TABLE_INDEX_I32 && |
1473 | Rel.Type != wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB) |
1474 | return; |
1475 | assert(Rel.Symbol->isFunction())((Rel.Symbol->isFunction()) ? static_cast<void> (0) : __assert_fail ("Rel.Symbol->isFunction()", "/build/llvm-toolchain-snapshot-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1475, __PRETTY_FUNCTION__)); |
1476 | const MCSymbolWasm &WS = *ResolveSymbol(*Rel.Symbol); |
1477 | uint32_t FunctionIndex = WasmIndices.find(&WS)->second; |
1478 | uint32_t TableIndex = TableElems.size() + kInitialTableOffset; |
1479 | if (TableIndices.try_emplace(&WS, TableIndex).second) { |
1480 | LLVM_DEBUG(dbgs() << " -> adding " << WS.getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> adding " << WS.getName () << " to table: " << TableIndex << "\n"; } } while (false) |
1481 | << " to table: " << TableIndex << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("mc")) { dbgs() << " -> adding " << WS.getName () << " to table: " << TableIndex << "\n"; } } while (false); |
1482 | TableElems.push_back(FunctionIndex); |
1483 | registerFunctionType(WS); |
1484 | } |
1485 | }; |
1486 | |
1487 | for (const WasmRelocationEntry &RelEntry : CodeRelocations) |
1488 | HandleReloc(RelEntry); |
1489 | for (const WasmRelocationEntry &RelEntry : DataRelocations) |
1490 | HandleReloc(RelEntry); |
1491 | } |
1492 | |
1493 | // Translate .init_array section contents into start functions. |
1494 | for (const MCSection &S : Asm) { |
1495 | const auto &WS = static_cast<const MCSectionWasm &>(S); |
1496 | if (WS.getSectionName().startswith(".fini_array")) |
1497 | report_fatal_error(".fini_array sections are unsupported"); |
1498 | if (!WS.getSectionName().startswith(".init_array")) |
1499 | continue; |
1500 | if (WS.getFragmentList().empty()) |
1501 | continue; |
1502 | |
1503 | // init_array is expected to contain a single non-empty data fragment |
1504 | if (WS.getFragmentList().size() != 3) |
1505 | report_fatal_error("only one .init_array section fragment supported"); |
1506 | |
1507 | auto IT = WS.begin(); |
1508 | const MCFragment &EmptyFrag = *IT; |
1509 | if (EmptyFrag.getKind() != MCFragment::FT_Data) |
1510 | report_fatal_error(".init_array section should be aligned"); |
1511 | |
1512 | IT = std::next(IT); |
1513 | const MCFragment &AlignFrag = *IT; |
1514 | if (AlignFrag.getKind() != MCFragment::FT_Align) |
1515 | report_fatal_error(".init_array section should be aligned"); |
1516 | if (cast<MCAlignFragment>(AlignFrag).getAlignment() != (is64Bit() ? 8 : 4)) |
1517 | report_fatal_error(".init_array section should be aligned for pointers"); |
1518 | |
1519 | const MCFragment &Frag = *std::next(IT); |
1520 | if (Frag.hasInstructions() || Frag.getKind() != MCFragment::FT_Data) |
1521 | report_fatal_error("only data supported in .init_array section"); |
1522 | |
1523 | uint16_t Priority = UINT16_MAX(65535); |
1524 | unsigned PrefixLength = strlen(".init_array"); |
1525 | if (WS.getSectionName().size() > PrefixLength) { |
1526 | if (WS.getSectionName()[PrefixLength] != '.') |
1527 | report_fatal_error( |
1528 | ".init_array section priority should start with '.'"); |
1529 | if (WS.getSectionName() |
1530 | .substr(PrefixLength + 1) |
1531 | .getAsInteger(10, Priority)) |
1532 | report_fatal_error("invalid .init_array section priority"); |
1533 | } |
1534 | const auto &DataFrag = cast<MCDataFragment>(Frag); |
1535 | const SmallVectorImpl<char> &Contents = DataFrag.getContents(); |
1536 | for (const uint8_t * |
1537 | p = (const uint8_t *)Contents.data(), |
1538 | *end = (const uint8_t *)Contents.data() + Contents.size(); |
1539 | p != end; ++p) { |
1540 | if (*p != 0) |
1541 | report_fatal_error("non-symbolic data in .init_array section"); |
1542 | } |
1543 | for (const MCFixup &Fixup : DataFrag.getFixups()) { |
1544 | 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-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1545, __PRETTY_FUNCTION__)) |
1545 | 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-8~svn350071/lib/MC/WasmObjectWriter.cpp" , 1545, __PRETTY_FUNCTION__)); |
1546 | const MCExpr *Expr = Fixup.getValue(); |
1547 | auto *Sym = dyn_cast<MCSymbolRefExpr>(Expr); |
1548 | if (!Sym) |
1549 | report_fatal_error("fixups in .init_array should be symbol references"); |
1550 | if (Sym->getKind() != MCSymbolRefExpr::VK_WebAssembly_FUNCTION) |
1551 | report_fatal_error("symbols in .init_array should be for functions"); |
1552 | if (Sym->getSymbol().getIndex() == INVALID_INDEX) |
1553 | report_fatal_error("symbols in .init_array should exist in symbtab"); |
1554 | InitFuncs.push_back( |
1555 | std::make_pair(Priority, Sym->getSymbol().getIndex())); |
1556 | } |
1557 | } |
1558 | |
1559 | // Write out the Wasm header. |
1560 | writeHeader(Asm); |
1561 | |
1562 | writeTypeSection(Signatures); |
1563 | writeImportSection(Imports, DataSize, TableElems.size()); |
1564 | writeFunctionSection(Functions); |
1565 | // Skip the "table" section; we import the table instead. |
1566 | // Skip the "memory" section; we import the memory instead. |
1567 | writeGlobalSection(); |
1568 | writeEventSection(Events); |
1569 | writeExportSection(Exports); |
1570 | writeElemSection(TableElems); |
1571 | writeCodeSection(Asm, Layout, Functions); |
1572 | writeDataSection(); |
1573 | writeCustomSections(Asm, Layout); |
1574 | writeLinkingMetaDataSection(SymbolInfos, InitFuncs, Comdats); |
1575 | writeRelocSection(CodeSectionIndex, "CODE", CodeRelocations); |
1576 | writeRelocSection(DataSectionIndex, "DATA", DataRelocations); |
1577 | writeCustomRelocSections(); |
1578 | |
1579 | // TODO: Translate the .comment section to the output. |
1580 | return W.OS.tell() - StartOffset; |
1581 | } |
1582 | |
1583 | std::unique_ptr<MCObjectWriter> |
1584 | llvm::createWasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW, |
1585 | raw_pwrite_stream &OS) { |
1586 | return llvm::make_unique<WasmObjectWriter>(std::move(MOTW), OS); |
1587 | } |