1//===- SyntheticSections.cpp ----------------------------------------------===//
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 contains linker-synthesized sections.
10//
11//===----------------------------------------------------------------------===//
12
13#include "SyntheticSections.h"
14
15#include "InputChunks.h"
16#include "InputElement.h"
17#include "OutputSegment.h"
18#include "SymbolTable.h"
19#include "llvm/BinaryFormat/Wasm.h"
20#include "llvm/Support/Path.h"
21#include <optional>
22
23using namespace llvm;
24using namespace llvm::wasm;
25
26namespace lld::wasm {
27
28OutStruct out;
29
30namespace {
31
32// Some synthetic sections (e.g. "name" and "linking") have subsections.
33// Just like the synthetic sections themselves these need to be created before
34// they can be written out (since they are preceded by their length). This
35// class is used to create subsections and then write them into the stream
36// of the parent section.
37class SubSection {
38public:
39 explicit SubSection(uint32_t type) : type(type) {}
40
41 void writeTo(raw_ostream &to) {
42 writeUleb128(os&: to, number: type, msg: "subsection type");
43 writeUleb128(os&: to, number: body.size(), msg: "subsection size");
44 to.write(Ptr: body.data(), Size: body.size());
45 }
46
47private:
48 uint32_t type;
49 std::string body;
50
51public:
52 raw_string_ostream os{body};
53};
54
55} // namespace
56
57bool DylinkSection::isNeeded() const {
58 return ctx.isPic ||
59 ctx.arg.unresolvedSymbols == UnresolvedPolicy::ImportDynamic ||
60 !ctx.sharedFiles.empty();
61}
62
63void DylinkSection::writeBody() {
64 raw_ostream &os = bodyOutputStream;
65
66 {
67 SubSection sub(WASM_DYLINK_MEM_INFO);
68 writeUleb128(os&: sub.os, number: memSize, msg: "MemSize");
69 writeUleb128(os&: sub.os, number: memAlign, msg: "MemAlign");
70 writeUleb128(os&: sub.os, number: out.elemSec->numEntries(), msg: "TableSize");
71 writeUleb128(os&: sub.os, number: 0, msg: "TableAlign");
72 sub.writeTo(to&: os);
73 }
74
75 if (ctx.sharedFiles.size()) {
76 SubSection sub(WASM_DYLINK_NEEDED);
77 writeUleb128(os&: sub.os, number: ctx.sharedFiles.size(), msg: "Needed");
78 for (auto *so : ctx.sharedFiles)
79 writeStr(os&: sub.os, string: llvm::sys::path::filename(path: so->getName()), msg: "so name");
80 sub.writeTo(to&: os);
81 }
82
83 // Under certain circumstances we need to include extra information about our
84 // exports and/or imports to the dynamic linker.
85 // For exports we need to notify the linker when an export is TLS since the
86 // exported value is relative to __tls_base rather than __memory_base.
87 // For imports we need to notify the dynamic linker when an import is weak
88 // so that knows not to report an error for such symbols.
89 std::vector<const Symbol *> importInfo;
90 std::vector<const Symbol *> exportInfo;
91 for (const Symbol *sym : symtab->symbols()) {
92 if (sym->isLive()) {
93 if (sym->isExported() && sym->isTLS() && isa<DefinedData>(Val: sym)) {
94 exportInfo.push_back(x: sym);
95 }
96 if (sym->isUndefWeak()) {
97 importInfo.push_back(x: sym);
98 }
99 }
100 }
101
102 if (!exportInfo.empty()) {
103 SubSection sub(WASM_DYLINK_EXPORT_INFO);
104 writeUleb128(os&: sub.os, number: exportInfo.size(), msg: "num exports");
105
106 for (const Symbol *sym : exportInfo) {
107 LLVM_DEBUG(llvm::dbgs() << "export info: " << toString(*sym) << "\n");
108 StringRef name = sym->getName();
109 if (auto *f = dyn_cast<DefinedFunction>(Val: sym)) {
110 if (std::optional<StringRef> exportName =
111 f->function->getExportName()) {
112 name = *exportName;
113 }
114 }
115 writeStr(os&: sub.os, string: name, msg: "sym name");
116 writeUleb128(os&: sub.os, number: sym->flags, msg: "sym flags");
117 }
118
119 sub.writeTo(to&: os);
120 }
121
122 if (!importInfo.empty()) {
123 SubSection sub(WASM_DYLINK_IMPORT_INFO);
124 writeUleb128(os&: sub.os, number: importInfo.size(), msg: "num imports");
125
126 for (const Symbol *sym : importInfo) {
127 LLVM_DEBUG(llvm::dbgs() << "imports info: " << toString(*sym) << "\n");
128 StringRef module = sym->importModule.value_or(u&: defaultModule);
129 StringRef name = sym->importName.value_or(u: sym->getName());
130 writeStr(os&: sub.os, string: module, msg: "import module");
131 writeStr(os&: sub.os, string: name, msg: "import name");
132 writeUleb128(os&: sub.os, number: sym->flags, msg: "sym flags");
133 }
134
135 sub.writeTo(to&: os);
136 }
137
138 if (!ctx.arg.rpath.empty()) {
139 SubSection sub(WASM_DYLINK_RUNTIME_PATH);
140 writeUleb128(os&: sub.os, number: ctx.arg.rpath.size(), msg: "num rpath entries");
141 for (const auto ref : ctx.arg.rpath)
142 writeStr(os&: sub.os, string: ref, msg: "rpath entry");
143 sub.writeTo(to&: os);
144 }
145}
146
147uint32_t TypeSection::registerType(const WasmSignature &sig) {
148 auto pair = typeIndices.insert(KV: std::make_pair(x: sig, y: types.size()));
149 if (pair.second) {
150 LLVM_DEBUG(llvm::dbgs() << "registerType " << toString(sig) << "\n");
151 types.push_back(x: &sig);
152 }
153 return pair.first->second;
154}
155
156uint32_t TypeSection::lookupType(const WasmSignature &sig) {
157 auto it = typeIndices.find(Val: sig);
158 if (it == typeIndices.end()) {
159 error(msg: "type not found: " + toString(sig));
160 return 0;
161 }
162 return it->second;
163}
164
165void TypeSection::writeBody() {
166 writeUleb128(os&: bodyOutputStream, number: types.size(), msg: "type count");
167 for (const WasmSignature *sig : types)
168 writeSig(os&: bodyOutputStream, sig: *sig);
169}
170
171uint32_t ImportSection::getNumImports() const {
172 assert(isSealed);
173 uint32_t numImports = importedSymbols.size() + gotSymbols.size();
174 if (ctx.arg.memoryImport.has_value())
175 ++numImports;
176 return numImports;
177}
178
179void ImportSection::addGOTEntry(Symbol *sym) {
180 assert(!isSealed);
181 if (sym->hasGOTIndex())
182 return;
183 LLVM_DEBUG(dbgs() << "addGOTEntry: " << toString(*sym) << "\n");
184 sym->setGOTIndex(numImportedGlobals++);
185 if (ctx.isPic) {
186 // Any symbol that is assigned an normal GOT entry must be exported
187 // otherwise the dynamic linker won't be able create the entry that contains
188 // it.
189 sym->forceExport = true;
190 }
191 gotSymbols.push_back(x: sym);
192}
193
194void ImportSection::addImport(Symbol *sym) {
195 assert(!isSealed);
196 StringRef module = sym->importModule.value_or(u&: defaultModule);
197 StringRef name = sym->importName.value_or(u: sym->getName());
198 if (auto *f = dyn_cast<FunctionSymbol>(Val: sym)) {
199 ImportKey<WasmSignature> key(*(f->getSignature()), module, name);
200 auto entry = importedFunctions.try_emplace(Key: key, Args&: numImportedFunctions);
201 if (entry.second) {
202 importedSymbols.emplace_back(args&: sym);
203 f->setFunctionIndex(numImportedFunctions++);
204 } else {
205 f->setFunctionIndex(entry.first->second);
206 }
207 } else if (auto *g = dyn_cast<GlobalSymbol>(Val: sym)) {
208 ImportKey<WasmGlobalType> key(*(g->getGlobalType()), module, name);
209 auto entry = importedGlobals.try_emplace(Key: key, Args&: numImportedGlobals);
210 if (entry.second) {
211 importedSymbols.emplace_back(args&: sym);
212 g->setGlobalIndex(numImportedGlobals++);
213 } else {
214 g->setGlobalIndex(entry.first->second);
215 }
216 } else if (auto *t = dyn_cast<TagSymbol>(Val: sym)) {
217 ImportKey<WasmSignature> key(*(t->getSignature()), module, name);
218 auto entry = importedTags.try_emplace(Key: key, Args&: numImportedTags);
219 if (entry.second) {
220 importedSymbols.emplace_back(args&: sym);
221 t->setTagIndex(numImportedTags++);
222 } else {
223 t->setTagIndex(entry.first->second);
224 }
225 } else {
226 assert(TableSymbol::classof(sym));
227 auto *table = cast<TableSymbol>(Val: sym);
228 ImportKey<WasmTableType> key(*(table->getTableType()), module, name);
229 auto entry = importedTables.try_emplace(Key: key, Args&: numImportedTables);
230 if (entry.second) {
231 importedSymbols.emplace_back(args&: sym);
232 table->setTableNumber(numImportedTables++);
233 } else {
234 table->setTableNumber(entry.first->second);
235 }
236 }
237}
238
239void ImportSection::writeBody() {
240 raw_ostream &os = bodyOutputStream;
241
242 writeUleb128(os, number: getNumImports(), msg: "import count");
243
244 bool is64 = ctx.arg.is64.value_or(u: false);
245
246 if (ctx.arg.memoryImport) {
247 WasmImport import;
248 import.Module = ctx.arg.memoryImport->first;
249 import.Field = ctx.arg.memoryImport->second;
250 import.Kind = WASM_EXTERNAL_MEMORY;
251 import.Memory.Flags = 0;
252 import.Memory.Minimum = out.memorySec->numMemoryPages;
253 if (out.memorySec->maxMemoryPages != 0 || ctx.arg.sharedMemory) {
254 import.Memory.Flags |= WASM_LIMITS_FLAG_HAS_MAX;
255 import.Memory.Maximum = out.memorySec->maxMemoryPages;
256 }
257 if (ctx.arg.sharedMemory)
258 import.Memory.Flags |= WASM_LIMITS_FLAG_IS_SHARED;
259 if (is64)
260 import.Memory.Flags |= WASM_LIMITS_FLAG_IS_64;
261 writeImport(os, import);
262 }
263
264 for (const Symbol *sym : importedSymbols) {
265 WasmImport import;
266 import.Field = sym->importName.value_or(u: sym->getName());
267 import.Module = sym->importModule.value_or(u&: defaultModule);
268
269 if (auto *functionSym = dyn_cast<FunctionSymbol>(Val: sym)) {
270 import.Kind = WASM_EXTERNAL_FUNCTION;
271 import.SigIndex = out.typeSec->lookupType(sig: *functionSym->signature);
272 } else if (auto *globalSym = dyn_cast<GlobalSymbol>(Val: sym)) {
273 import.Kind = WASM_EXTERNAL_GLOBAL;
274 import.Global = *globalSym->getGlobalType();
275 } else if (auto *tagSym = dyn_cast<TagSymbol>(Val: sym)) {
276 import.Kind = WASM_EXTERNAL_TAG;
277 import.SigIndex = out.typeSec->lookupType(sig: *tagSym->signature);
278 } else {
279 auto *tableSym = cast<TableSymbol>(Val: sym);
280 import.Kind = WASM_EXTERNAL_TABLE;
281 import.Table = *tableSym->getTableType();
282 }
283 writeImport(os, import);
284 }
285
286 for (const Symbol *sym : gotSymbols) {
287 WasmImport import;
288 import.Kind = WASM_EXTERNAL_GLOBAL;
289 auto ptrType = is64 ? WASM_TYPE_I64 : WASM_TYPE_I32;
290 import.Global = {.Type: static_cast<uint8_t>(ptrType), .Mutable: true};
291 if (isa<DataSymbol>(Val: sym))
292 import.Module = "GOT.mem";
293 else
294 import.Module = "GOT.func";
295 import.Field = sym->getName();
296 writeImport(os, import);
297 }
298}
299
300void FunctionSection::writeBody() {
301 raw_ostream &os = bodyOutputStream;
302
303 writeUleb128(os, number: inputFunctions.size(), msg: "function count");
304 for (const InputFunction *func : inputFunctions)
305 writeUleb128(os, number: out.typeSec->lookupType(sig: func->signature), msg: "sig index");
306}
307
308void FunctionSection::addFunction(InputFunction *func) {
309 if (!func->live)
310 return;
311 uint32_t functionIndex =
312 out.importSec->getNumImportedFunctions() + inputFunctions.size();
313 inputFunctions.emplace_back(args&: func);
314 func->setFunctionIndex(functionIndex);
315}
316
317void TableSection::writeBody() {
318 raw_ostream &os = bodyOutputStream;
319
320 writeUleb128(os, number: inputTables.size(), msg: "table count");
321 for (const InputTable *table : inputTables)
322 writeTableType(os, type: table->getType());
323}
324
325void TableSection::addTable(InputTable *table) {
326 if (!table->live)
327 return;
328 // Some inputs require that the indirect function table be assigned to table
329 // number 0.
330 if (ctx.legacyFunctionTable &&
331 isa<DefinedTable>(Val: ctx.sym.indirectFunctionTable) &&
332 cast<DefinedTable>(Val: ctx.sym.indirectFunctionTable)->table == table) {
333 if (out.importSec->getNumImportedTables()) {
334 // Alack! Some other input imported a table, meaning that we are unable
335 // to assign table number 0 to the indirect function table.
336 for (const auto *culprit : out.importSec->importedSymbols) {
337 if (isa<UndefinedTable>(Val: culprit)) {
338 error(msg: "object file not built with 'reference-types' or "
339 "'call-indirect-overlong' feature conflicts with import of "
340 "table " +
341 culprit->getName() + " by file " +
342 toString(file: culprit->getFile()));
343 return;
344 }
345 }
346 llvm_unreachable("failed to find conflicting table import");
347 }
348 inputTables.insert(position: inputTables.begin(), x: table);
349 return;
350 }
351 inputTables.push_back(x: table);
352}
353
354void TableSection::assignIndexes() {
355 uint32_t tableNumber = out.importSec->getNumImportedTables();
356 for (InputTable *t : inputTables)
357 t->assignIndex(index: tableNumber++);
358}
359
360void MemorySection::writeBody() {
361 raw_ostream &os = bodyOutputStream;
362
363 bool hasMax = maxMemoryPages != 0 || ctx.arg.sharedMemory;
364 writeUleb128(os, number: 1, msg: "memory count");
365 unsigned flags = 0;
366 if (hasMax)
367 flags |= WASM_LIMITS_FLAG_HAS_MAX;
368 if (ctx.arg.sharedMemory)
369 flags |= WASM_LIMITS_FLAG_IS_SHARED;
370 if (ctx.arg.is64.value_or(u: false))
371 flags |= WASM_LIMITS_FLAG_IS_64;
372 if (ctx.arg.pageSize != WasmDefaultPageSize)
373 flags |= WASM_LIMITS_FLAG_HAS_PAGE_SIZE;
374 writeUleb128(os, number: flags, msg: "memory limits flags");
375 writeUleb128(os, number: numMemoryPages, msg: "initial pages");
376 if (hasMax)
377 writeUleb128(os, number: maxMemoryPages, msg: "max pages");
378 if (ctx.arg.pageSize != WasmDefaultPageSize)
379 writeUleb128(os, number: llvm::Log2_64(Value: ctx.arg.pageSize), msg: "page size");
380}
381
382void TagSection::writeBody() {
383 raw_ostream &os = bodyOutputStream;
384
385 writeUleb128(os, number: inputTags.size(), msg: "tag count");
386 for (InputTag *t : inputTags) {
387 writeUleb128(os, number: 0, msg: "tag attribute"); // Reserved "attribute" field
388 writeUleb128(os, number: out.typeSec->lookupType(sig: t->signature), msg: "sig index");
389 }
390}
391
392void TagSection::addTag(InputTag *tag) {
393 if (!tag->live)
394 return;
395 uint32_t tagIndex = out.importSec->getNumImportedTags() + inputTags.size();
396 LLVM_DEBUG(dbgs() << "addTag: " << tagIndex << "\n");
397 tag->assignIndex(index: tagIndex);
398 inputTags.push_back(x: tag);
399}
400
401void GlobalSection::assignIndexes() {
402 uint32_t globalIndex = out.importSec->getNumImportedGlobals();
403 for (InputGlobal *g : inputGlobals)
404 g->assignIndex(index: globalIndex++);
405 for (Symbol *sym : internalGotSymbols)
406 sym->setGOTIndex(globalIndex++);
407 isSealed = true;
408}
409
410static void ensureIndirectFunctionTable() {
411 if (!ctx.sym.indirectFunctionTable)
412 ctx.sym.indirectFunctionTable =
413 symtab->resolveIndirectFunctionTable(/*required =*/true);
414}
415
416void GlobalSection::addInternalGOTEntry(Symbol *sym) {
417 assert(!isSealed);
418 if (sym->requiresGOT)
419 return;
420 LLVM_DEBUG(dbgs() << "addInternalGOTEntry: " << sym->getName() << " "
421 << toString(sym->kind()) << "\n");
422 sym->requiresGOT = true;
423 if (auto *F = dyn_cast<FunctionSymbol>(Val: sym)) {
424 ensureIndirectFunctionTable();
425 out.elemSec->addEntry(sym: F);
426 }
427 internalGotSymbols.push_back(x: sym);
428}
429
430void GlobalSection::generateRelocationCode(raw_ostream &os, bool TLS) const {
431 assert(!ctx.arg.extendedConst);
432 bool is64 = ctx.arg.is64.value_or(u: false);
433 unsigned opcode_ptr_const = is64 ? WASM_OPCODE_I64_CONST
434 : WASM_OPCODE_I32_CONST;
435 unsigned opcode_ptr_add = is64 ? WASM_OPCODE_I64_ADD
436 : WASM_OPCODE_I32_ADD;
437
438 for (const Symbol *sym : internalGotSymbols) {
439 if (TLS != sym->isTLS())
440 continue;
441
442 if (auto *d = dyn_cast<DefinedData>(Val: sym)) {
443 // Get __memory_base
444 writeU8(os, byte: WASM_OPCODE_GLOBAL_GET, msg: "GLOBAL_GET");
445 if (sym->isTLS())
446 writeUleb128(os, number: ctx.sym.tlsBase->getGlobalIndex(), msg: "__tls_base");
447 else
448 writeUleb128(os, number: ctx.sym.memoryBase->getGlobalIndex(), msg: "__memory_base");
449
450 // Add the virtual address of the data symbol
451 writeU8(os, byte: opcode_ptr_const, msg: "CONST");
452 writeSleb128(os, number: d->getVA(), msg: "offset");
453 } else if (auto *f = dyn_cast<FunctionSymbol>(Val: sym)) {
454 if (f->isStub)
455 continue;
456 // Get __table_base
457 writeU8(os, byte: WASM_OPCODE_GLOBAL_GET, msg: "GLOBAL_GET");
458 writeUleb128(os, number: ctx.sym.tableBase->getGlobalIndex(), msg: "__table_base");
459
460 // Add the table index to __table_base
461 writeU8(os, byte: opcode_ptr_const, msg: "CONST");
462 writeSleb128(os, number: f->getTableIndex(), msg: "offset");
463 } else {
464 assert(isa<UndefinedData>(sym) || isa<SharedData>(sym));
465 continue;
466 }
467 writeU8(os, byte: opcode_ptr_add, msg: "ADD");
468 writeU8(os, byte: WASM_OPCODE_GLOBAL_SET, msg: "GLOBAL_SET");
469 writeUleb128(os, number: sym->getGOTIndex(), msg: "got_entry");
470 }
471}
472
473void GlobalSection::writeBody() {
474 raw_ostream &os = bodyOutputStream;
475
476 writeUleb128(os, number: numGlobals(), msg: "global count");
477 for (InputGlobal *g : inputGlobals) {
478 writeGlobalType(os, type: g->getType());
479 writeInitExpr(os, initExpr: g->getInitExpr());
480 }
481 bool is64 = ctx.arg.is64.value_or(u: false);
482 uint8_t itype = is64 ? WASM_TYPE_I64 : WASM_TYPE_I32;
483 for (const Symbol *sym : internalGotSymbols) {
484 bool mutable_ = false;
485 if (!sym->isStub) {
486 // In the case of dynamic linking, unless we have 'extended-const'
487 // available, these global must to be mutable since they get updated to
488 // the correct runtime value during `__wasm_apply_global_relocs`.
489 if (!ctx.arg.extendedConst && ctx.isPic && !sym->isTLS())
490 mutable_ = true;
491 // With multi-theadeding any TLS globals must be mutable since they get
492 // set during `__wasm_apply_global_tls_relocs`
493 if (ctx.arg.sharedMemory && sym->isTLS())
494 mutable_ = true;
495 }
496 WasmGlobalType type{.Type: itype, .Mutable: mutable_};
497 writeGlobalType(os, type);
498
499 bool useExtendedConst = false;
500 uint32_t globalIdx;
501 int64_t offset;
502 if (ctx.arg.extendedConst && ctx.isPic) {
503 if (auto *d = dyn_cast<DefinedData>(Val: sym)) {
504 if (!sym->isTLS()) {
505 globalIdx = ctx.sym.memoryBase->getGlobalIndex();
506 offset = d->getVA();
507 useExtendedConst = true;
508 }
509 } else if (auto *f = dyn_cast<FunctionSymbol>(Val: sym)) {
510 if (!sym->isStub) {
511 globalIdx = ctx.sym.tableBase->getGlobalIndex();
512 offset = f->getTableIndex();
513 useExtendedConst = true;
514 }
515 }
516 }
517 if (useExtendedConst) {
518 // We can use an extended init expression to add a constant
519 // offset of __memory_base/__table_base.
520 writeU8(os, byte: WASM_OPCODE_GLOBAL_GET, msg: "global get");
521 writeUleb128(os, number: globalIdx, msg: "literal (global index)");
522 if (offset) {
523 writePtrConst(os, number: offset, is64, msg: "offset");
524 writeU8(os, byte: is64 ? WASM_OPCODE_I64_ADD : WASM_OPCODE_I32_ADD, msg: "add");
525 }
526 writeU8(os, byte: WASM_OPCODE_END, msg: "opcode:end");
527 } else {
528 WasmInitExpr initExpr;
529 if (auto *d = dyn_cast<DefinedData>(Val: sym))
530 // In the sharedMemory case TLS globals are set during
531 // `__wasm_apply_global_tls_relocs`, but in the non-shared case
532 // we know the absolute value at link time.
533 initExpr = intConst(value: d->getVA(/*absolute=*/!ctx.arg.sharedMemory), is64);
534 else if (auto *f = dyn_cast<FunctionSymbol>(Val: sym))
535 initExpr = intConst(value: f->isStub ? 0 : f->getTableIndex(), is64);
536 else {
537 assert(isa<UndefinedData>(sym) || isa<SharedData>(sym));
538 initExpr = intConst(value: 0, is64);
539 }
540 writeInitExpr(os, initExpr);
541 }
542 }
543 for (const DefinedData *sym : dataAddressGlobals) {
544 WasmGlobalType type{.Type: itype, .Mutable: false};
545 writeGlobalType(os, type);
546 writeInitExpr(os, initExpr: intConst(value: sym->getVA(), is64));
547 }
548}
549
550void GlobalSection::addGlobal(InputGlobal *global) {
551 assert(!isSealed);
552 if (!global->live)
553 return;
554 inputGlobals.push_back(x: global);
555}
556
557void ExportSection::writeBody() {
558 raw_ostream &os = bodyOutputStream;
559
560 writeUleb128(os, number: exports.size(), msg: "export count");
561 for (const WasmExport &export_ : exports)
562 writeExport(os, export_);
563}
564
565bool StartSection::isNeeded() const { return ctx.sym.startFunction != nullptr; }
566
567void StartSection::writeBody() {
568 raw_ostream &os = bodyOutputStream;
569 writeUleb128(os, number: ctx.sym.startFunction->getFunctionIndex(), msg: "function index");
570}
571
572void ElemSection::addEntry(FunctionSymbol *sym) {
573 // Don't add stub functions to the wasm table. The address of all stub
574 // functions should be zero and they should they don't appear in the table.
575 // They only exist so that the calls to missing functions can validate.
576 if (sym->hasTableIndex() || sym->isStub)
577 return;
578 sym->setTableIndex(ctx.arg.tableBase + indirectFunctions.size());
579 indirectFunctions.emplace_back(args&: sym);
580}
581
582void ElemSection::writeBody() {
583 raw_ostream &os = bodyOutputStream;
584
585 assert(ctx.sym.indirectFunctionTable);
586 writeUleb128(os, number: 1, msg: "segment count");
587 uint32_t tableNumber = ctx.sym.indirectFunctionTable->getTableNumber();
588 uint32_t flags = 0;
589 if (tableNumber)
590 flags |= WASM_ELEM_SEGMENT_HAS_TABLE_NUMBER;
591 writeUleb128(os, number: flags, msg: "elem segment flags");
592 if (flags & WASM_ELEM_SEGMENT_HAS_TABLE_NUMBER)
593 writeUleb128(os, number: tableNumber, msg: "table number");
594
595 WasmInitExpr initExpr;
596 initExpr.Extended = false;
597 if (ctx.isPic) {
598 initExpr.Inst.Opcode = WASM_OPCODE_GLOBAL_GET;
599 initExpr.Inst.Value.Global = ctx.sym.tableBase->getGlobalIndex();
600 } else {
601 bool is64 = ctx.arg.is64.value_or(u: false);
602 initExpr = intConst(value: ctx.arg.tableBase, is64);
603 }
604 writeInitExpr(os, initExpr);
605
606 if (flags & WASM_ELEM_SEGMENT_MASK_HAS_ELEM_DESC) {
607 // We only write active function table initializers, for which the elem kind
608 // is specified to be written as 0x00 and interpreted to mean "funcref".
609 const uint8_t elemKind = 0;
610 writeU8(os, byte: elemKind, msg: "elem kind");
611 }
612
613 writeUleb128(os, number: indirectFunctions.size(), msg: "elem count");
614 uint32_t tableIndex = ctx.arg.tableBase;
615 for (const FunctionSymbol *sym : indirectFunctions) {
616 assert(sym->getTableIndex() == tableIndex);
617 (void) tableIndex;
618 writeUleb128(os, number: sym->getFunctionIndex(), msg: "function index");
619 ++tableIndex;
620 }
621}
622
623DataCountSection::DataCountSection(ArrayRef<OutputSegment *> segments)
624 : SyntheticSection(llvm::wasm::WASM_SEC_DATACOUNT),
625 numSegments(llvm::count_if(Range&: segments, P: [](OutputSegment *const segment) {
626 return segment->requiredInBinary();
627 })) {}
628
629void DataCountSection::writeBody() {
630 writeUleb128(os&: bodyOutputStream, number: numSegments, msg: "data count");
631}
632
633bool DataCountSection::isNeeded() const {
634 return numSegments && ctx.arg.sharedMemory;
635}
636
637void LinkingSection::writeBody() {
638 raw_ostream &os = bodyOutputStream;
639
640 writeUleb128(os, number: WasmMetadataVersion, msg: "Version");
641
642 if (!symtabEntries.empty()) {
643 SubSection sub(WASM_SYMBOL_TABLE);
644 writeUleb128(os&: sub.os, number: symtabEntries.size(), msg: "num symbols");
645
646 for (const Symbol *sym : symtabEntries) {
647 assert(sym->isDefined() || sym->isUndefined());
648 WasmSymbolType kind = sym->getWasmType();
649 uint32_t flags = sym->flags;
650
651 writeU8(os&: sub.os, byte: kind, msg: "sym kind");
652 writeUleb128(os&: sub.os, number: flags, msg: "sym flags");
653
654 if (auto *f = dyn_cast<FunctionSymbol>(Val: sym)) {
655 if (auto *d = dyn_cast<DefinedFunction>(Val: sym)) {
656 writeUleb128(os&: sub.os, number: d->getExportedFunctionIndex(), msg: "index");
657 } else {
658 writeUleb128(os&: sub.os, number: f->getFunctionIndex(), msg: "index");
659 }
660 if (sym->isDefined() || (flags & WASM_SYMBOL_EXPLICIT_NAME) != 0)
661 writeStr(os&: sub.os, string: sym->getName(), msg: "sym name");
662 } else if (auto *g = dyn_cast<GlobalSymbol>(Val: sym)) {
663 writeUleb128(os&: sub.os, number: g->getGlobalIndex(), msg: "index");
664 if (sym->isDefined() || (flags & WASM_SYMBOL_EXPLICIT_NAME) != 0)
665 writeStr(os&: sub.os, string: sym->getName(), msg: "sym name");
666 } else if (auto *t = dyn_cast<TagSymbol>(Val: sym)) {
667 writeUleb128(os&: sub.os, number: t->getTagIndex(), msg: "index");
668 if (sym->isDefined() || (flags & WASM_SYMBOL_EXPLICIT_NAME) != 0)
669 writeStr(os&: sub.os, string: sym->getName(), msg: "sym name");
670 } else if (auto *t = dyn_cast<TableSymbol>(Val: sym)) {
671 writeUleb128(os&: sub.os, number: t->getTableNumber(), msg: "table number");
672 if (sym->isDefined() || (flags & WASM_SYMBOL_EXPLICIT_NAME) != 0)
673 writeStr(os&: sub.os, string: sym->getName(), msg: "sym name");
674 } else if (isa<DataSymbol>(Val: sym)) {
675 writeStr(os&: sub.os, string: sym->getName(), msg: "sym name");
676 if (auto *dataSym = dyn_cast<DefinedData>(Val: sym)) {
677 if (dataSym->segment) {
678 writeUleb128(os&: sub.os, number: dataSym->getOutputSegmentIndex(), msg: "index");
679 writeUleb128(os&: sub.os, number: dataSym->getOutputSegmentOffset(),
680 msg: "data offset");
681 } else {
682 writeUleb128(os&: sub.os, number: 0, msg: "index");
683 writeUleb128(os&: sub.os, number: dataSym->getVA(), msg: "data offset");
684 }
685 writeUleb128(os&: sub.os, number: dataSym->getSize(), msg: "data size");
686 }
687 } else {
688 auto *s = cast<OutputSectionSymbol>(Val: sym);
689 writeUleb128(os&: sub.os, number: s->section->sectionIndex, msg: "sym section index");
690 }
691 }
692
693 sub.writeTo(to&: os);
694 }
695
696 if (dataSegments.size()) {
697 SubSection sub(WASM_SEGMENT_INFO);
698 writeUleb128(os&: sub.os, number: dataSegments.size(), msg: "num data segments");
699 for (const OutputSegment *s : dataSegments) {
700 writeStr(os&: sub.os, string: s->name, msg: "segment name");
701 writeUleb128(os&: sub.os, number: s->alignment, msg: "alignment");
702 writeUleb128(os&: sub.os, number: s->linkingFlags, msg: "flags");
703 }
704 sub.writeTo(to&: os);
705 }
706
707 if (!initFunctions.empty()) {
708 SubSection sub(WASM_INIT_FUNCS);
709 writeUleb128(os&: sub.os, number: initFunctions.size(), msg: "num init functions");
710 for (const WasmInitEntry &f : initFunctions) {
711 writeUleb128(os&: sub.os, number: f.priority, msg: "priority");
712 writeUleb128(os&: sub.os, number: f.sym->getOutputSymbolIndex(), msg: "function index");
713 }
714 sub.writeTo(to&: os);
715 }
716
717 struct ComdatEntry {
718 unsigned kind;
719 uint32_t index;
720 };
721 std::map<StringRef, std::vector<ComdatEntry>> comdats;
722
723 for (const InputFunction *f : out.functionSec->inputFunctions) {
724 StringRef comdat = f->getComdatName();
725 if (!comdat.empty())
726 comdats[comdat].emplace_back(
727 args: ComdatEntry{.kind: WASM_COMDAT_FUNCTION, .index: f->getFunctionIndex()});
728 }
729 for (uint32_t i = 0; i < dataSegments.size(); ++i) {
730 const auto &inputSegments = dataSegments[i]->inputSegments;
731 if (inputSegments.empty())
732 continue;
733 StringRef comdat = inputSegments[0]->getComdatName();
734#ifndef NDEBUG
735 for (const InputChunk *isec : inputSegments)
736 assert(isec->getComdatName() == comdat);
737#endif
738 if (!comdat.empty())
739 comdats[comdat].emplace_back(args: ComdatEntry{.kind: WASM_COMDAT_DATA, .index: i});
740 }
741
742 if (!comdats.empty()) {
743 SubSection sub(WASM_COMDAT_INFO);
744 writeUleb128(os&: sub.os, number: comdats.size(), msg: "num comdats");
745 for (const auto &c : comdats) {
746 writeStr(os&: sub.os, string: c.first, msg: "comdat name");
747 writeUleb128(os&: sub.os, number: 0, msg: "comdat flags"); // flags for future use
748 writeUleb128(os&: sub.os, number: c.second.size(), msg: "num entries");
749 for (const ComdatEntry &entry : c.second) {
750 writeU8(os&: sub.os, byte: entry.kind, msg: "entry kind");
751 writeUleb128(os&: sub.os, number: entry.index, msg: "entry index");
752 }
753 }
754 sub.writeTo(to&: os);
755 }
756}
757
758void LinkingSection::addToSymtab(Symbol *sym) {
759 sym->setOutputSymbolIndex(symtabEntries.size());
760 symtabEntries.emplace_back(args&: sym);
761}
762
763unsigned NameSection::numNamedFunctions() const {
764 unsigned numNames = out.importSec->getNumImportedFunctions();
765
766 for (const InputFunction *f : out.functionSec->inputFunctions)
767 if (!f->name.empty() || !f->debugName.empty())
768 ++numNames;
769
770 return numNames;
771}
772
773unsigned NameSection::numNamedGlobals() const {
774 unsigned numNames = out.importSec->getNumImportedGlobals();
775
776 for (const InputGlobal *g : out.globalSec->inputGlobals)
777 if (!g->getName().empty())
778 ++numNames;
779
780 numNames += out.globalSec->internalGotSymbols.size();
781 return numNames;
782}
783
784unsigned NameSection::numNamedDataSegments() const {
785 unsigned numNames = 0;
786
787 for (const OutputSegment *s : segments)
788 if (!s->name.empty() && s->requiredInBinary())
789 ++numNames;
790
791 return numNames;
792}
793
794// Create the custom "name" section containing debug symbol names.
795void NameSection::writeBody() {
796 {
797 SubSection sub(WASM_NAMES_MODULE);
798 StringRef moduleName = ctx.arg.soName;
799 if (ctx.arg.soName.empty())
800 moduleName = llvm::sys::path::filename(path: ctx.arg.outputFile);
801 writeStr(os&: sub.os, string: moduleName, msg: "module name");
802 sub.writeTo(to&: bodyOutputStream);
803 }
804
805 unsigned count = numNamedFunctions();
806 if (count) {
807 SubSection sub(WASM_NAMES_FUNCTION);
808 writeUleb128(os&: sub.os, number: count, msg: "name count");
809
810 // Function names appear in function index order. As it happens
811 // importedSymbols and inputFunctions are numbered in order with imported
812 // functions coming first.
813 for (const Symbol *s : out.importSec->importedSymbols) {
814 if (auto *f = dyn_cast<FunctionSymbol>(Val: s)) {
815 writeUleb128(os&: sub.os, number: f->getFunctionIndex(), msg: "func index");
816 writeStr(os&: sub.os, string: toString(sym: *s), msg: "symbol name");
817 }
818 }
819 for (const InputFunction *f : out.functionSec->inputFunctions) {
820 if (!f->name.empty()) {
821 writeUleb128(os&: sub.os, number: f->getFunctionIndex(), msg: "func index");
822 if (!f->debugName.empty()) {
823 writeStr(os&: sub.os, string: f->debugName, msg: "symbol name");
824 } else {
825 writeStr(os&: sub.os, string: maybeDemangleSymbol(name: f->name), msg: "symbol name");
826 }
827 }
828 }
829 sub.writeTo(to&: bodyOutputStream);
830 }
831
832 count = numNamedGlobals();
833 if (count) {
834 SubSection sub(WASM_NAMES_GLOBAL);
835 writeUleb128(os&: sub.os, number: count, msg: "name count");
836
837 for (const Symbol *s : out.importSec->importedSymbols) {
838 if (auto *g = dyn_cast<GlobalSymbol>(Val: s)) {
839 writeUleb128(os&: sub.os, number: g->getGlobalIndex(), msg: "global index");
840 writeStr(os&: sub.os, string: toString(sym: *s), msg: "symbol name");
841 }
842 }
843 for (const Symbol *s : out.importSec->gotSymbols) {
844 writeUleb128(os&: sub.os, number: s->getGOTIndex(), msg: "global index");
845 writeStr(os&: sub.os, string: toString(sym: *s), msg: "symbol name");
846 }
847 for (const InputGlobal *g : out.globalSec->inputGlobals) {
848 if (!g->getName().empty()) {
849 writeUleb128(os&: sub.os, number: g->getAssignedIndex(), msg: "global index");
850 writeStr(os&: sub.os, string: maybeDemangleSymbol(name: g->getName()), msg: "symbol name");
851 }
852 }
853 for (Symbol *s : out.globalSec->internalGotSymbols) {
854 writeUleb128(os&: sub.os, number: s->getGOTIndex(), msg: "global index");
855 if (isa<FunctionSymbol>(Val: s))
856 writeStr(os&: sub.os, string: "GOT.func.internal." + toString(sym: *s), msg: "symbol name");
857 else
858 writeStr(os&: sub.os, string: "GOT.data.internal." + toString(sym: *s), msg: "symbol name");
859 }
860
861 sub.writeTo(to&: bodyOutputStream);
862 }
863
864 count = numNamedDataSegments();
865 if (count) {
866 SubSection sub(WASM_NAMES_DATA_SEGMENT);
867 writeUleb128(os&: sub.os, number: count, msg: "name count");
868
869 for (OutputSegment *s : segments) {
870 if (!s->name.empty() && s->requiredInBinary()) {
871 writeUleb128(os&: sub.os, number: s->index, msg: "global index");
872 writeStr(os&: sub.os, string: s->name, msg: "segment name");
873 }
874 }
875
876 sub.writeTo(to&: bodyOutputStream);
877 }
878}
879
880void ProducersSection::addInfo(const WasmProducerInfo &info) {
881 for (auto &producers :
882 {std::make_pair(x: &info.Languages, y: &languages),
883 std::make_pair(x: &info.Tools, y: &tools), std::make_pair(x: &info.SDKs, y: &sDKs)})
884 for (auto &producer : *producers.first)
885 if (llvm::none_of(Range&: *producers.second,
886 P: [&](std::pair<std::string, std::string> seen) {
887 return seen.first == producer.first;
888 }))
889 producers.second->push_back(Elt: producer);
890}
891
892void ProducersSection::writeBody() {
893 auto &os = bodyOutputStream;
894 writeUleb128(os, number: fieldCount(), msg: "field count");
895 for (auto &field :
896 {std::make_pair(x: "language", y&: languages),
897 std::make_pair(x: "processed-by", y&: tools), std::make_pair(x: "sdk", y&: sDKs)}) {
898 if (field.second.empty())
899 continue;
900 writeStr(os, string: field.first, msg: "field name");
901 writeUleb128(os, number: field.second.size(), msg: "number of entries");
902 for (auto &entry : field.second) {
903 writeStr(os, string: entry.first, msg: "producer name");
904 writeStr(os, string: entry.second, msg: "producer version");
905 }
906 }
907}
908
909void TargetFeaturesSection::writeBody() {
910 SmallVector<std::string, 8> emitted(features.begin(), features.end());
911 llvm::sort(C&: emitted);
912 auto &os = bodyOutputStream;
913 writeUleb128(os, number: emitted.size(), msg: "feature count");
914 for (auto &feature : emitted) {
915 writeU8(os, byte: WASM_FEATURE_PREFIX_USED, msg: "feature used prefix");
916 writeStr(os, string: feature, msg: "feature name");
917 }
918}
919
920void RelocSection::writeBody() {
921 uint32_t count = sec->getNumRelocations();
922 assert(sec->sectionIndex != UINT32_MAX);
923 writeUleb128(os&: bodyOutputStream, number: sec->sectionIndex, msg: "reloc section");
924 writeUleb128(os&: bodyOutputStream, number: count, msg: "reloc count");
925 sec->writeRelocations(os&: bodyOutputStream);
926}
927
928static size_t getHashSize() {
929 switch (ctx.arg.buildId) {
930 case BuildIdKind::Fast:
931 case BuildIdKind::Uuid:
932 return 16;
933 case BuildIdKind::Sha1:
934 return 20;
935 case BuildIdKind::Hexstring:
936 return ctx.arg.buildIdVector.size();
937 case BuildIdKind::None:
938 return 0;
939 }
940 llvm_unreachable("build id kind not implemented");
941}
942
943BuildIdSection::BuildIdSection()
944 : SyntheticSection(llvm::wasm::WASM_SEC_CUSTOM, buildIdSectionName),
945 hashSize(getHashSize()) {}
946
947void BuildIdSection::writeBody() {
948 LLVM_DEBUG(llvm::dbgs() << "BuildId writebody\n");
949 // Write hash size
950 auto &os = bodyOutputStream;
951 writeUleb128(os, number: hashSize, msg: "build id size");
952 writeBytes(os, bytes: std::vector<char>(hashSize, ' ').data(), count: hashSize,
953 msg: "placeholder");
954}
955
956void BuildIdSection::writeBuildId(llvm::ArrayRef<uint8_t> buf) {
957 assert(buf.size() == hashSize);
958 LLVM_DEBUG(dbgs() << "buildid write " << buf.size() << " "
959 << hashPlaceholderPtr << '\n');
960 memcpy(dest: hashPlaceholderPtr, src: buf.data(), n: hashSize);
961}
962
963} // namespace wasm::lld
964