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Dan Gohman18eafb62017-02-22 01:23:18 +00001//===- 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"
Zachary Turner264b5d92017-06-07 03:48:56 +000016#include "llvm/BinaryFormat/Wasm.h"
Dan Gohman18eafb62017-02-22 01:23:18 +000017#include "llvm/MC/MCAsmBackend.h"
18#include "llvm/MC/MCAsmInfo.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/MCObjectFileInfo.h"
25#include "llvm/MC/MCObjectWriter.h"
26#include "llvm/MC/MCSectionWasm.h"
27#include "llvm/MC/MCSymbolWasm.h"
28#include "llvm/MC/MCValue.h"
29#include "llvm/MC/MCWasmObjectWriter.h"
Dan Gohmand934cb82017-02-24 23:18:00 +000030#include "llvm/Support/Casting.h"
Dan Gohman18eafb62017-02-22 01:23:18 +000031#include "llvm/Support/Debug.h"
Dan Gohman18eafb62017-02-22 01:23:18 +000032#include "llvm/Support/ErrorHandling.h"
Dan Gohmand934cb82017-02-24 23:18:00 +000033#include "llvm/Support/LEB128.h"
Dan Gohman18eafb62017-02-22 01:23:18 +000034#include "llvm/Support/StringSaver.h"
35#include <vector>
36
37using namespace llvm;
38
Sam Clegg5e3d33a2017-07-07 02:01:29 +000039#define DEBUG_TYPE "mc"
Dan Gohman18eafb62017-02-22 01:23:18 +000040
41namespace {
Sam Clegg9e15f352017-06-03 02:01:24 +000042
Dan Gohmand934cb82017-02-24 23:18:00 +000043// For patching purposes, we need to remember where each section starts, both
44// for patching up the section size field, and for patching up references to
45// locations within the section.
46struct SectionBookkeeping {
47 // Where the size of the section is written.
48 uint64_t SizeOffset;
49 // Where the contents of the section starts (after the header).
50 uint64_t ContentsOffset;
51};
52
Sam Clegg9e15f352017-06-03 02:01:24 +000053// The signature of a wasm function, in a struct capable of being used as a
54// DenseMap key.
55struct WasmFunctionType {
56 // Support empty and tombstone instances, needed by DenseMap.
57 enum { Plain, Empty, Tombstone } State;
58
59 // The return types of the function.
60 SmallVector<wasm::ValType, 1> Returns;
61
62 // The parameter types of the function.
63 SmallVector<wasm::ValType, 4> Params;
64
65 WasmFunctionType() : State(Plain) {}
66
67 bool operator==(const WasmFunctionType &Other) const {
68 return State == Other.State && Returns == Other.Returns &&
69 Params == Other.Params;
70 }
71};
72
73// Traits for using WasmFunctionType in a DenseMap.
74struct WasmFunctionTypeDenseMapInfo {
75 static WasmFunctionType getEmptyKey() {
76 WasmFunctionType FuncTy;
77 FuncTy.State = WasmFunctionType::Empty;
78 return FuncTy;
79 }
80 static WasmFunctionType getTombstoneKey() {
81 WasmFunctionType FuncTy;
82 FuncTy.State = WasmFunctionType::Tombstone;
83 return FuncTy;
84 }
85 static unsigned getHashValue(const WasmFunctionType &FuncTy) {
86 uintptr_t Value = FuncTy.State;
87 for (wasm::ValType Ret : FuncTy.Returns)
88 Value += DenseMapInfo<int32_t>::getHashValue(int32_t(Ret));
89 for (wasm::ValType Param : FuncTy.Params)
90 Value += DenseMapInfo<int32_t>::getHashValue(int32_t(Param));
91 return Value;
92 }
93 static bool isEqual(const WasmFunctionType &LHS,
94 const WasmFunctionType &RHS) {
95 return LHS == RHS;
96 }
97};
98
Sam Clegg7c395942017-09-14 23:07:53 +000099// A wasm data segment. A wasm binary contains only a single data section
100// but that can contain many segments, each with their own virtual location
101// in memory. Each MCSection data created by llvm is modeled as its own
102// wasm data segment.
103struct WasmDataSegment {
104 MCSectionWasm *Section;
Sam Cleggd95ed952017-09-20 19:03:35 +0000105 StringRef Name;
Sam Clegg7c395942017-09-14 23:07:53 +0000106 uint32_t Offset;
Sam Clegg63ebb812017-09-29 16:50:08 +0000107 uint32_t Alignment;
108 uint32_t Flags;
Sam Clegg7c395942017-09-14 23:07:53 +0000109 SmallVector<char, 4> Data;
110};
111
Sam Clegg9e15f352017-06-03 02:01:24 +0000112// A wasm import to be written into the import section.
113struct WasmImport {
114 StringRef ModuleName;
115 StringRef FieldName;
116 unsigned Kind;
117 int32_t Type;
118};
119
120// A wasm function to be written into the function section.
121struct WasmFunction {
122 int32_t Type;
123 const MCSymbolWasm *Sym;
124};
125
126// A wasm export to be written into the export section.
127struct WasmExport {
128 StringRef FieldName;
129 unsigned Kind;
130 uint32_t Index;
131};
132
133// A wasm global to be written into the global section.
134struct WasmGlobal {
135 wasm::ValType Type;
136 bool IsMutable;
137 bool HasImport;
138 uint64_t InitialValue;
139 uint32_t ImportIndex;
140};
141
Sam Clegg6dc65e92017-06-06 16:38:59 +0000142// Information about a single relocation.
143struct WasmRelocationEntry {
Sam Cleggfe6414b2017-06-21 23:46:41 +0000144 uint64_t Offset; // Where is the relocation.
145 const MCSymbolWasm *Symbol; // The symbol to relocate with.
146 int64_t Addend; // A value to add to the symbol.
147 unsigned Type; // The type of the relocation.
148 const MCSectionWasm *FixupSection;// The section the relocation is targeting.
Sam Clegg6dc65e92017-06-06 16:38:59 +0000149
150 WasmRelocationEntry(uint64_t Offset, const MCSymbolWasm *Symbol,
151 int64_t Addend, unsigned Type,
Sam Cleggfe6414b2017-06-21 23:46:41 +0000152 const MCSectionWasm *FixupSection)
Sam Clegg6dc65e92017-06-06 16:38:59 +0000153 : Offset(Offset), Symbol(Symbol), Addend(Addend), Type(Type),
154 FixupSection(FixupSection) {}
155
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000156 bool hasAddend() const {
157 switch (Type) {
Sam Clegg13a2e892017-09-01 17:32:01 +0000158 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_LEB:
159 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
160 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32:
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000161 return true;
162 default:
163 return false;
164 }
165 }
166
Sam Clegg6dc65e92017-06-06 16:38:59 +0000167 void print(raw_ostream &Out) const {
Sam Clegg9bf73c02017-07-05 20:25:08 +0000168 Out << "Off=" << Offset << ", Sym=" << *Symbol << ", Addend=" << Addend
Sam Clegg759631c2017-09-15 20:54:59 +0000169 << ", Type=" << Type
170 << ", FixupSection=" << FixupSection->getSectionName();
Sam Clegg6dc65e92017-06-06 16:38:59 +0000171 }
Sam Cleggb7787fd2017-06-20 04:04:59 +0000172
Aaron Ballman615eb472017-10-15 14:32:27 +0000173#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
Sam Cleggb7787fd2017-06-20 04:04:59 +0000174 LLVM_DUMP_METHOD void dump() const { print(dbgs()); }
175#endif
Sam Clegg6dc65e92017-06-06 16:38:59 +0000176};
177
Sam Clegg1fb8daa2017-06-20 05:05:10 +0000178#if !defined(NDEBUG)
Sam Clegg7f055de2017-06-20 04:47:58 +0000179raw_ostream &operator<<(raw_ostream &OS, const WasmRelocationEntry &Rel) {
Sam Cleggb7787fd2017-06-20 04:04:59 +0000180 Rel.print(OS);
181 return OS;
182}
Sam Clegg1fb8daa2017-06-20 05:05:10 +0000183#endif
Sam Cleggb7787fd2017-06-20 04:04:59 +0000184
Dan Gohman18eafb62017-02-22 01:23:18 +0000185class WasmObjectWriter : public MCObjectWriter {
186 /// Helper struct for containing some precomputed information on symbols.
187 struct WasmSymbolData {
188 const MCSymbolWasm *Symbol;
189 StringRef Name;
190
191 // Support lexicographic sorting.
192 bool operator<(const WasmSymbolData &RHS) const { return Name < RHS.Name; }
193 };
194
195 /// The target specific Wasm writer instance.
196 std::unique_ptr<MCWasmObjectTargetWriter> TargetObjectWriter;
197
Dan Gohmand934cb82017-02-24 23:18:00 +0000198 // Relocations for fixing up references in the code section.
199 std::vector<WasmRelocationEntry> CodeRelocations;
200
201 // Relocations for fixing up references in the data section.
202 std::vector<WasmRelocationEntry> DataRelocations;
203
Dan Gohmand934cb82017-02-24 23:18:00 +0000204 // Index values to use for fixing up call_indirect type indices.
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000205 // Maps function symbols to the index of the type of the function
206 DenseMap<const MCSymbolWasm *, uint32_t> TypeIndices;
Sam Cleggd99f6072017-06-12 23:52:44 +0000207 // Maps function symbols to the table element index space. Used
208 // for TABLE_INDEX relocation types (i.e. address taken functions).
209 DenseMap<const MCSymbolWasm *, uint32_t> IndirectSymbolIndices;
210 // Maps function/global symbols to the function/global index space.
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000211 DenseMap<const MCSymbolWasm *, uint32_t> SymbolIndices;
212
213 DenseMap<WasmFunctionType, int32_t, WasmFunctionTypeDenseMapInfo>
214 FunctionTypeIndices;
Sam Clegg5e3d33a2017-07-07 02:01:29 +0000215 SmallVector<WasmFunctionType, 4> FunctionTypes;
Sam Clegg7c395942017-09-14 23:07:53 +0000216 SmallVector<WasmGlobal, 4> Globals;
217 unsigned NumGlobalImports = 0;
Dan Gohmand934cb82017-02-24 23:18:00 +0000218
Dan Gohman18eafb62017-02-22 01:23:18 +0000219 // TargetObjectWriter wrappers.
220 bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
Sam Cleggae03c1e72017-06-13 18:51:50 +0000221 unsigned getRelocType(const MCValue &Target, const MCFixup &Fixup) const {
222 return TargetObjectWriter->getRelocType(Target, Fixup);
Dan Gohman18eafb62017-02-22 01:23:18 +0000223 }
224
Dan Gohmand934cb82017-02-24 23:18:00 +0000225 void startSection(SectionBookkeeping &Section, unsigned SectionId,
226 const char *Name = nullptr);
227 void endSection(SectionBookkeeping &Section);
228
Dan Gohman18eafb62017-02-22 01:23:18 +0000229public:
Lang Hames1301a872017-10-10 01:15:10 +0000230 WasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW,
231 raw_pwrite_stream &OS)
232 : MCObjectWriter(OS, /*IsLittleEndian=*/true),
233 TargetObjectWriter(std::move(MOTW)) {}
Dan Gohman18eafb62017-02-22 01:23:18 +0000234
Dan Gohmand934cb82017-02-24 23:18:00 +0000235private:
Dan Gohman18eafb62017-02-22 01:23:18 +0000236 ~WasmObjectWriter() override;
237
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000238 void reset() override {
239 CodeRelocations.clear();
240 DataRelocations.clear();
241 TypeIndices.clear();
242 SymbolIndices.clear();
Sam Cleggd99f6072017-06-12 23:52:44 +0000243 IndirectSymbolIndices.clear();
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000244 FunctionTypeIndices.clear();
Sam Clegg5e3d33a2017-07-07 02:01:29 +0000245 FunctionTypes.clear();
Sam Clegg7c395942017-09-14 23:07:53 +0000246 Globals.clear();
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000247 MCObjectWriter::reset();
Sam Clegg7c395942017-09-14 23:07:53 +0000248 NumGlobalImports = 0;
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000249 }
250
Dan Gohman18eafb62017-02-22 01:23:18 +0000251 void writeHeader(const MCAssembler &Asm);
252
253 void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
254 const MCFragment *Fragment, const MCFixup &Fixup,
Rafael Espindolaceecfe5b2017-07-11 23:56:10 +0000255 MCValue Target, uint64_t &FixedValue) override;
Dan Gohman18eafb62017-02-22 01:23:18 +0000256
257 void executePostLayoutBinding(MCAssembler &Asm,
258 const MCAsmLayout &Layout) override;
259
260 void writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
Sam Clegg9e15f352017-06-03 02:01:24 +0000261
Sam Cleggb7787fd2017-06-20 04:04:59 +0000262 void writeString(const StringRef Str) {
263 encodeULEB128(Str.size(), getStream());
264 writeBytes(Str);
265 }
266
Sam Clegg9e15f352017-06-03 02:01:24 +0000267 void writeValueType(wasm::ValType Ty) {
268 encodeSLEB128(int32_t(Ty), getStream());
269 }
270
Sam Clegg457fb0b2017-09-15 19:50:44 +0000271 void writeTypeSection(ArrayRef<WasmFunctionType> FunctionTypes);
272 void writeImportSection(ArrayRef<WasmImport> Imports);
273 void writeFunctionSection(ArrayRef<WasmFunction> Functions);
Sam Cleggd99f6072017-06-12 23:52:44 +0000274 void writeTableSection(uint32_t NumElements);
Sam Clegg7c395942017-09-14 23:07:53 +0000275 void writeMemorySection(uint32_t DataSize);
276 void writeGlobalSection();
Sam Clegg457fb0b2017-09-15 19:50:44 +0000277 void writeExportSection(ArrayRef<WasmExport> Exports);
278 void writeElemSection(ArrayRef<uint32_t> TableElems);
Sam Clegg9e15f352017-06-03 02:01:24 +0000279 void writeCodeSection(const MCAssembler &Asm, const MCAsmLayout &Layout,
Sam Clegg457fb0b2017-09-15 19:50:44 +0000280 ArrayRef<WasmFunction> Functions);
281 void writeDataSection(ArrayRef<WasmDataSegment> Segments);
282 void writeNameSection(ArrayRef<WasmFunction> Functions,
283 ArrayRef<WasmImport> Imports,
Sam Clegg9e15f352017-06-03 02:01:24 +0000284 uint32_t NumFuncImports);
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000285 void writeCodeRelocSection();
Sam Clegg7c395942017-09-14 23:07:53 +0000286 void writeDataRelocSection();
Sam Clegg31a2c802017-09-20 21:17:04 +0000287 void writeLinkingMetaDataSection(
288 ArrayRef<WasmDataSegment> Segments, uint32_t DataSize,
Sam Clegg31a2c802017-09-20 21:17:04 +0000289 SmallVector<std::pair<StringRef, uint32_t>, 4> SymbolFlags,
290 bool HasStackPointer, uint32_t StackPointerGlobal);
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000291
Sam Clegg7c395942017-09-14 23:07:53 +0000292 uint32_t getProvisionalValue(const WasmRelocationEntry &RelEntry);
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000293 void applyRelocations(ArrayRef<WasmRelocationEntry> Relocations,
294 uint64_t ContentsOffset);
295
Sam Clegg7c395942017-09-14 23:07:53 +0000296 void writeRelocations(ArrayRef<WasmRelocationEntry> Relocations);
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000297 uint32_t getRelocationIndexValue(const WasmRelocationEntry &RelEntry);
Sam Clegg5e3d33a2017-07-07 02:01:29 +0000298 uint32_t getFunctionType(const MCSymbolWasm& Symbol);
299 uint32_t registerFunctionType(const MCSymbolWasm& Symbol);
Dan Gohman18eafb62017-02-22 01:23:18 +0000300};
Sam Clegg9e15f352017-06-03 02:01:24 +0000301
Dan Gohman18eafb62017-02-22 01:23:18 +0000302} // end anonymous namespace
303
304WasmObjectWriter::~WasmObjectWriter() {}
305
Dan Gohmand934cb82017-02-24 23:18:00 +0000306// Write out a section header and a patchable section size field.
307void WasmObjectWriter::startSection(SectionBookkeeping &Section,
308 unsigned SectionId,
309 const char *Name) {
310 assert((Name != nullptr) == (SectionId == wasm::WASM_SEC_CUSTOM) &&
311 "Only custom sections can have names");
312
Sam Cleggb7787fd2017-06-20 04:04:59 +0000313 DEBUG(dbgs() << "startSection " << SectionId << ": " << Name << "\n");
Derek Schuffe2688c42017-03-14 20:23:22 +0000314 encodeULEB128(SectionId, getStream());
Dan Gohmand934cb82017-02-24 23:18:00 +0000315
316 Section.SizeOffset = getStream().tell();
317
318 // The section size. We don't know the size yet, so reserve enough space
319 // for any 32-bit value; we'll patch it later.
320 encodeULEB128(UINT32_MAX, getStream());
321
322 // The position where the section starts, for measuring its size.
323 Section.ContentsOffset = getStream().tell();
324
325 // Custom sections in wasm also have a string identifier.
326 if (SectionId == wasm::WASM_SEC_CUSTOM) {
Sam Cleggb7787fd2017-06-20 04:04:59 +0000327 assert(Name);
328 writeString(StringRef(Name));
Dan Gohmand934cb82017-02-24 23:18:00 +0000329 }
330}
331
332// Now that the section is complete and we know how big it is, patch up the
333// section size field at the start of the section.
334void WasmObjectWriter::endSection(SectionBookkeeping &Section) {
335 uint64_t Size = getStream().tell() - Section.ContentsOffset;
336 if (uint32_t(Size) != Size)
337 report_fatal_error("section size does not fit in a uint32_t");
338
Sam Cleggb7787fd2017-06-20 04:04:59 +0000339 DEBUG(dbgs() << "endSection size=" << Size << "\n");
Dan Gohmand934cb82017-02-24 23:18:00 +0000340
341 // Write the final section size to the payload_len field, which follows
342 // the section id byte.
343 uint8_t Buffer[16];
Sam Clegg66a99e42017-09-15 20:34:47 +0000344 unsigned SizeLen = encodeULEB128(Size, Buffer, 5);
Dan Gohmand934cb82017-02-24 23:18:00 +0000345 assert(SizeLen == 5);
346 getStream().pwrite((char *)Buffer, SizeLen, Section.SizeOffset);
347}
348
Dan Gohman18eafb62017-02-22 01:23:18 +0000349// Emit the Wasm header.
350void WasmObjectWriter::writeHeader(const MCAssembler &Asm) {
Dan Gohman7ea5adf2017-02-22 18:50:20 +0000351 writeBytes(StringRef(wasm::WasmMagic, sizeof(wasm::WasmMagic)));
352 writeLE32(wasm::WasmVersion);
Dan Gohman18eafb62017-02-22 01:23:18 +0000353}
354
355void WasmObjectWriter::executePostLayoutBinding(MCAssembler &Asm,
356 const MCAsmLayout &Layout) {
357}
358
359void WasmObjectWriter::recordRelocation(MCAssembler &Asm,
360 const MCAsmLayout &Layout,
361 const MCFragment *Fragment,
362 const MCFixup &Fixup, MCValue Target,
Rafael Espindolaceecfe5b2017-07-11 23:56:10 +0000363 uint64_t &FixedValue) {
364 MCAsmBackend &Backend = Asm.getBackend();
365 bool IsPCRel = Backend.getFixupKindInfo(Fixup.getKind()).Flags &
366 MCFixupKindInfo::FKF_IsPCRel;
Sam Cleggfe6414b2017-06-21 23:46:41 +0000367 const auto &FixupSection = cast<MCSectionWasm>(*Fragment->getParent());
Dan Gohmand934cb82017-02-24 23:18:00 +0000368 uint64_t C = Target.getConstant();
369 uint64_t FixupOffset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
370 MCContext &Ctx = Asm.getContext();
371
372 if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
373 assert(RefB->getKind() == MCSymbolRefExpr::VK_None &&
374 "Should not have constructed this");
375
376 // Let A, B and C being the components of Target and R be the location of
377 // the fixup. If the fixup is not pcrel, we want to compute (A - B + C).
378 // If it is pcrel, we want to compute (A - B + C - R).
379
380 // In general, Wasm has no relocations for -B. It can only represent (A + C)
381 // or (A + C - R). If B = R + K and the relocation is not pcrel, we can
382 // replace B to implement it: (A - R - K + C)
383 if (IsPCRel) {
384 Ctx.reportError(
385 Fixup.getLoc(),
386 "No relocation available to represent this relative expression");
387 return;
388 }
389
390 const auto &SymB = cast<MCSymbolWasm>(RefB->getSymbol());
391
392 if (SymB.isUndefined()) {
393 Ctx.reportError(Fixup.getLoc(),
394 Twine("symbol '") + SymB.getName() +
395 "' can not be undefined in a subtraction expression");
396 return;
397 }
398
399 assert(!SymB.isAbsolute() && "Should have been folded");
400 const MCSection &SecB = SymB.getSection();
401 if (&SecB != &FixupSection) {
402 Ctx.reportError(Fixup.getLoc(),
403 "Cannot represent a difference across sections");
404 return;
405 }
406
407 uint64_t SymBOffset = Layout.getSymbolOffset(SymB);
408 uint64_t K = SymBOffset - FixupOffset;
409 IsPCRel = true;
410 C -= K;
411 }
412
413 // We either rejected the fixup or folded B into C at this point.
414 const MCSymbolRefExpr *RefA = Target.getSymA();
415 const auto *SymA = RefA ? cast<MCSymbolWasm>(&RefA->getSymbol()) : nullptr;
416
Dan Gohmand934cb82017-02-24 23:18:00 +0000417 if (SymA && SymA->isVariable()) {
418 const MCExpr *Expr = SymA->getVariableValue();
Sam Clegg6ad8f192017-07-11 02:21:57 +0000419 const auto *Inner = cast<MCSymbolRefExpr>(Expr);
420 if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF)
421 llvm_unreachable("weakref used in reloc not yet implemented");
Dan Gohmand934cb82017-02-24 23:18:00 +0000422 }
423
424 // Put any constant offset in an addend. Offsets can be negative, and
425 // LLVM expects wrapping, in contrast to wasm's immediates which can't
426 // be negative and don't wrap.
427 FixedValue = 0;
428
Sam Clegg6ad8f192017-07-11 02:21:57 +0000429 if (SymA)
430 SymA->setUsedInReloc();
Dan Gohmand934cb82017-02-24 23:18:00 +0000431
Sam Cleggae03c1e72017-06-13 18:51:50 +0000432 assert(!IsPCRel);
Sam Clegg9d24fb72017-06-16 23:59:10 +0000433 assert(SymA);
434
Sam Cleggae03c1e72017-06-13 18:51:50 +0000435 unsigned Type = getRelocType(Target, Fixup);
436
Dan Gohmand934cb82017-02-24 23:18:00 +0000437 WasmRelocationEntry Rec(FixupOffset, SymA, C, Type, &FixupSection);
Sam Cleggb7787fd2017-06-20 04:04:59 +0000438 DEBUG(dbgs() << "WasmReloc: " << Rec << "\n");
Dan Gohmand934cb82017-02-24 23:18:00 +0000439
440 if (FixupSection.hasInstructions())
441 CodeRelocations.push_back(Rec);
442 else
443 DataRelocations.push_back(Rec);
444}
445
Dan Gohmand934cb82017-02-24 23:18:00 +0000446// Write X as an (unsigned) LEB value at offset Offset in Stream, padded
447// to allow patching.
448static void
449WritePatchableLEB(raw_pwrite_stream &Stream, uint32_t X, uint64_t Offset) {
450 uint8_t Buffer[5];
Sam Clegg66a99e42017-09-15 20:34:47 +0000451 unsigned SizeLen = encodeULEB128(X, Buffer, 5);
Dan Gohmand934cb82017-02-24 23:18:00 +0000452 assert(SizeLen == 5);
453 Stream.pwrite((char *)Buffer, SizeLen, Offset);
454}
455
456// Write X as an signed LEB value at offset Offset in Stream, padded
457// to allow patching.
458static void
459WritePatchableSLEB(raw_pwrite_stream &Stream, int32_t X, uint64_t Offset) {
460 uint8_t Buffer[5];
Sam Clegg66a99e42017-09-15 20:34:47 +0000461 unsigned SizeLen = encodeSLEB128(X, Buffer, 5);
Dan Gohmand934cb82017-02-24 23:18:00 +0000462 assert(SizeLen == 5);
463 Stream.pwrite((char *)Buffer, SizeLen, Offset);
464}
465
466// Write X as a plain integer value at offset Offset in Stream.
467static void WriteI32(raw_pwrite_stream &Stream, uint32_t X, uint64_t Offset) {
468 uint8_t Buffer[4];
469 support::endian::write32le(Buffer, X);
470 Stream.pwrite((char *)Buffer, sizeof(Buffer), Offset);
471}
472
Sam Cleggaff1c4d2017-09-15 19:22:01 +0000473static const MCSymbolWasm* ResolveSymbol(const MCSymbolWasm& Symbol) {
474 if (Symbol.isVariable()) {
475 const MCExpr *Expr = Symbol.getVariableValue();
476 auto *Inner = cast<MCSymbolRefExpr>(Expr);
477 return cast<MCSymbolWasm>(&Inner->getSymbol());
478 }
479 return &Symbol;
480}
481
Dan Gohmand934cb82017-02-24 23:18:00 +0000482// Compute a value to write into the code at the location covered
483// by RelEntry. This value isn't used by the static linker, since
484// we have addends; it just serves to make the code more readable
485// and to make standalone wasm modules directly usable.
Sam Clegg7c395942017-09-14 23:07:53 +0000486uint32_t
487WasmObjectWriter::getProvisionalValue(const WasmRelocationEntry &RelEntry) {
Sam Cleggaff1c4d2017-09-15 19:22:01 +0000488 const MCSymbolWasm *Sym = ResolveSymbol(*RelEntry.Symbol);
Dan Gohmand934cb82017-02-24 23:18:00 +0000489
490 // For undefined symbols, use a hopefully invalid value.
Sam Cleggb7787fd2017-06-20 04:04:59 +0000491 if (!Sym->isDefined(/*SetUsed=*/false))
Dan Gohmand934cb82017-02-24 23:18:00 +0000492 return UINT32_MAX;
493
Sam Clegg7c395942017-09-14 23:07:53 +0000494 uint32_t GlobalIndex = SymbolIndices[Sym];
495 const WasmGlobal& Global = Globals[GlobalIndex - NumGlobalImports];
496 uint64_t Address = Global.InitialValue + RelEntry.Addend;
Dan Gohmand934cb82017-02-24 23:18:00 +0000497
498 // Ignore overflow. LLVM allows address arithmetic to silently wrap.
499 uint32_t Value = Address;
500
501 return Value;
502}
503
Sam Clegg759631c2017-09-15 20:54:59 +0000504static void addData(SmallVectorImpl<char> &DataBytes,
Sam Clegg63ebb812017-09-29 16:50:08 +0000505 MCSectionWasm &DataSection) {
Sam Clegg759631c2017-09-15 20:54:59 +0000506 DEBUG(errs() << "addData: " << DataSection.getSectionName() << "\n");
507
Sam Clegg63ebb812017-09-29 16:50:08 +0000508 DataBytes.resize(alignTo(DataBytes.size(), DataSection.getAlignment()));
509
Sam Clegg759631c2017-09-15 20:54:59 +0000510 for (const MCFragment &Frag : DataSection) {
511 if (Frag.hasInstructions())
512 report_fatal_error("only data supported in data sections");
513
514 if (auto *Align = dyn_cast<MCAlignFragment>(&Frag)) {
515 if (Align->getValueSize() != 1)
516 report_fatal_error("only byte values supported for alignment");
517 // If nops are requested, use zeros, as this is the data section.
518 uint8_t Value = Align->hasEmitNops() ? 0 : Align->getValue();
519 uint64_t Size = std::min<uint64_t>(alignTo(DataBytes.size(),
520 Align->getAlignment()),
521 DataBytes.size() +
522 Align->getMaxBytesToEmit());
523 DataBytes.resize(Size, Value);
524 } else if (auto *Fill = dyn_cast<MCFillFragment>(&Frag)) {
525 DataBytes.insert(DataBytes.end(), Fill->getSize(), Fill->getValue());
526 } else {
527 const auto &DataFrag = cast<MCDataFragment>(Frag);
528 const SmallVectorImpl<char> &Contents = DataFrag.getContents();
529
530 DataBytes.insert(DataBytes.end(), Contents.begin(), Contents.end());
531 }
532 }
533
534 DEBUG(dbgs() << "addData -> " << DataBytes.size() << "\n");
535}
536
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000537uint32_t WasmObjectWriter::getRelocationIndexValue(
538 const WasmRelocationEntry &RelEntry) {
539 switch (RelEntry.Type) {
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000540 case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
541 case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32:
Sam Cleggb7787fd2017-06-20 04:04:59 +0000542 if (!IndirectSymbolIndices.count(RelEntry.Symbol))
Sam Clegg5e3d33a2017-07-07 02:01:29 +0000543 report_fatal_error("symbol not found table index space: " +
Sam Cleggb7787fd2017-06-20 04:04:59 +0000544 RelEntry.Symbol->getName());
Sam Cleggd99f6072017-06-12 23:52:44 +0000545 return IndirectSymbolIndices[RelEntry.Symbol];
546 case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
Sam Clegg9d24fb72017-06-16 23:59:10 +0000547 case wasm::R_WEBASSEMBLY_GLOBAL_INDEX_LEB:
Sam Clegg13a2e892017-09-01 17:32:01 +0000548 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_LEB:
549 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
550 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32:
Sam Cleggb7787fd2017-06-20 04:04:59 +0000551 if (!SymbolIndices.count(RelEntry.Symbol))
Sam Clegg5e3d33a2017-07-07 02:01:29 +0000552 report_fatal_error("symbol not found function/global index space: " +
Sam Cleggb7787fd2017-06-20 04:04:59 +0000553 RelEntry.Symbol->getName());
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000554 return SymbolIndices[RelEntry.Symbol];
555 case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB:
Sam Cleggb7787fd2017-06-20 04:04:59 +0000556 if (!TypeIndices.count(RelEntry.Symbol))
Sam Clegg5e3d33a2017-07-07 02:01:29 +0000557 report_fatal_error("symbol not found in type index space: " +
Sam Cleggb7787fd2017-06-20 04:04:59 +0000558 RelEntry.Symbol->getName());
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000559 return TypeIndices[RelEntry.Symbol];
560 default:
561 llvm_unreachable("invalid relocation type");
562 }
563}
564
Dan Gohmand934cb82017-02-24 23:18:00 +0000565// Apply the portions of the relocation records that we can handle ourselves
566// directly.
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000567void WasmObjectWriter::applyRelocations(
568 ArrayRef<WasmRelocationEntry> Relocations, uint64_t ContentsOffset) {
569 raw_pwrite_stream &Stream = getStream();
Dan Gohmand934cb82017-02-24 23:18:00 +0000570 for (const WasmRelocationEntry &RelEntry : Relocations) {
571 uint64_t Offset = ContentsOffset +
572 RelEntry.FixupSection->getSectionOffset() +
573 RelEntry.Offset;
Dan Gohmand934cb82017-02-24 23:18:00 +0000574
Sam Cleggb7787fd2017-06-20 04:04:59 +0000575 DEBUG(dbgs() << "applyRelocation: " << RelEntry << "\n");
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000576 switch (RelEntry.Type) {
577 case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
578 case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
Sam Clegg9d24fb72017-06-16 23:59:10 +0000579 case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB:
580 case wasm::R_WEBASSEMBLY_GLOBAL_INDEX_LEB: {
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000581 uint32_t Index = getRelocationIndexValue(RelEntry);
582 WritePatchableSLEB(Stream, Index, Offset);
Dan Gohmand934cb82017-02-24 23:18:00 +0000583 break;
584 }
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000585 case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32: {
586 uint32_t Index = getRelocationIndexValue(RelEntry);
587 WriteI32(Stream, Index, Offset);
Dan Gohmand934cb82017-02-24 23:18:00 +0000588 break;
589 }
Sam Clegg13a2e892017-09-01 17:32:01 +0000590 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB: {
Sam Clegg7c395942017-09-14 23:07:53 +0000591 uint32_t Value = getProvisionalValue(RelEntry);
Dan Gohmand934cb82017-02-24 23:18:00 +0000592 WritePatchableSLEB(Stream, Value, Offset);
593 break;
594 }
Sam Clegg13a2e892017-09-01 17:32:01 +0000595 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_LEB: {
Sam Clegg7c395942017-09-14 23:07:53 +0000596 uint32_t Value = getProvisionalValue(RelEntry);
Dan Gohmand934cb82017-02-24 23:18:00 +0000597 WritePatchableLEB(Stream, Value, Offset);
598 break;
599 }
Sam Clegg13a2e892017-09-01 17:32:01 +0000600 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32: {
Sam Clegg7c395942017-09-14 23:07:53 +0000601 uint32_t Value = getProvisionalValue(RelEntry);
Dan Gohmand934cb82017-02-24 23:18:00 +0000602 WriteI32(Stream, Value, Offset);
603 break;
604 }
605 default:
Sam Clegg9d24fb72017-06-16 23:59:10 +0000606 llvm_unreachable("invalid relocation type");
Dan Gohmand934cb82017-02-24 23:18:00 +0000607 }
608 }
Dan Gohman18eafb62017-02-22 01:23:18 +0000609}
610
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000611// Write out the portions of the relocation records that the linker will
Dan Gohman970d02c2017-03-30 23:58:19 +0000612// need to handle.
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000613void WasmObjectWriter::writeRelocations(
Sam Clegg7c395942017-09-14 23:07:53 +0000614 ArrayRef<WasmRelocationEntry> Relocations) {
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000615 raw_pwrite_stream &Stream = getStream();
616 for (const WasmRelocationEntry& RelEntry : Relocations) {
Dan Gohman970d02c2017-03-30 23:58:19 +0000617
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000618 uint64_t Offset = RelEntry.Offset +
Sam Clegg7c395942017-09-14 23:07:53 +0000619 RelEntry.FixupSection->getSectionOffset();
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000620 uint32_t Index = getRelocationIndexValue(RelEntry);
Dan Gohman970d02c2017-03-30 23:58:19 +0000621
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000622 encodeULEB128(RelEntry.Type, Stream);
Dan Gohman970d02c2017-03-30 23:58:19 +0000623 encodeULEB128(Offset, Stream);
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000624 encodeULEB128(Index, Stream);
625 if (RelEntry.hasAddend())
626 encodeSLEB128(RelEntry.Addend, Stream);
Dan Gohman970d02c2017-03-30 23:58:19 +0000627 }
628}
629
Sam Clegg9e15f352017-06-03 02:01:24 +0000630void WasmObjectWriter::writeTypeSection(
Sam Clegg457fb0b2017-09-15 19:50:44 +0000631 ArrayRef<WasmFunctionType> FunctionTypes) {
Sam Clegg9e15f352017-06-03 02:01:24 +0000632 if (FunctionTypes.empty())
633 return;
634
635 SectionBookkeeping Section;
636 startSection(Section, wasm::WASM_SEC_TYPE);
637
638 encodeULEB128(FunctionTypes.size(), getStream());
639
640 for (const WasmFunctionType &FuncTy : FunctionTypes) {
641 encodeSLEB128(wasm::WASM_TYPE_FUNC, getStream());
642 encodeULEB128(FuncTy.Params.size(), getStream());
643 for (wasm::ValType Ty : FuncTy.Params)
644 writeValueType(Ty);
645 encodeULEB128(FuncTy.Returns.size(), getStream());
646 for (wasm::ValType Ty : FuncTy.Returns)
647 writeValueType(Ty);
648 }
649
650 endSection(Section);
651}
652
Sam Clegg457fb0b2017-09-15 19:50:44 +0000653void WasmObjectWriter::writeImportSection(ArrayRef<WasmImport> Imports) {
Sam Clegg9e15f352017-06-03 02:01:24 +0000654 if (Imports.empty())
655 return;
656
657 SectionBookkeeping Section;
658 startSection(Section, wasm::WASM_SEC_IMPORT);
659
660 encodeULEB128(Imports.size(), getStream());
661 for (const WasmImport &Import : Imports) {
Sam Cleggb7787fd2017-06-20 04:04:59 +0000662 writeString(Import.ModuleName);
663 writeString(Import.FieldName);
Sam Clegg9e15f352017-06-03 02:01:24 +0000664
665 encodeULEB128(Import.Kind, getStream());
666
667 switch (Import.Kind) {
668 case wasm::WASM_EXTERNAL_FUNCTION:
669 encodeULEB128(Import.Type, getStream());
670 break;
671 case wasm::WASM_EXTERNAL_GLOBAL:
672 encodeSLEB128(int32_t(Import.Type), getStream());
673 encodeULEB128(0, getStream()); // mutability
674 break;
675 default:
676 llvm_unreachable("unsupported import kind");
677 }
678 }
679
680 endSection(Section);
681}
682
Sam Clegg457fb0b2017-09-15 19:50:44 +0000683void WasmObjectWriter::writeFunctionSection(ArrayRef<WasmFunction> Functions) {
Sam Clegg9e15f352017-06-03 02:01:24 +0000684 if (Functions.empty())
685 return;
686
687 SectionBookkeeping Section;
688 startSection(Section, wasm::WASM_SEC_FUNCTION);
689
690 encodeULEB128(Functions.size(), getStream());
691 for (const WasmFunction &Func : Functions)
692 encodeULEB128(Func.Type, getStream());
693
694 endSection(Section);
695}
696
Sam Cleggd99f6072017-06-12 23:52:44 +0000697void WasmObjectWriter::writeTableSection(uint32_t NumElements) {
Sam Clegg9e15f352017-06-03 02:01:24 +0000698 // For now, always emit the table section, since indirect calls are not
699 // valid without it. In the future, we could perhaps be more clever and omit
700 // it if there are no indirect calls.
Sam Cleggd99f6072017-06-12 23:52:44 +0000701
Sam Clegg9e15f352017-06-03 02:01:24 +0000702 SectionBookkeeping Section;
703 startSection(Section, wasm::WASM_SEC_TABLE);
704
Sam Cleggd99f6072017-06-12 23:52:44 +0000705 encodeULEB128(1, getStream()); // The number of tables.
706 // Fixed to 1 for now.
707 encodeSLEB128(wasm::WASM_TYPE_ANYFUNC, getStream()); // Type of table
708 encodeULEB128(0, getStream()); // flags
709 encodeULEB128(NumElements, getStream()); // initial
Sam Clegg9e15f352017-06-03 02:01:24 +0000710
711 endSection(Section);
712}
713
Sam Clegg7c395942017-09-14 23:07:53 +0000714void WasmObjectWriter::writeMemorySection(uint32_t DataSize) {
Sam Clegg9e15f352017-06-03 02:01:24 +0000715 // For now, always emit the memory section, since loads and stores are not
716 // valid without it. In the future, we could perhaps be more clever and omit
717 // it if there are no loads or stores.
718 SectionBookkeeping Section;
Sam Clegg7c395942017-09-14 23:07:53 +0000719 uint32_t NumPages = (DataSize + wasm::WasmPageSize - 1) / wasm::WasmPageSize;
Sam Clegg9e15f352017-06-03 02:01:24 +0000720
721 startSection(Section, wasm::WASM_SEC_MEMORY);
722 encodeULEB128(1, getStream()); // number of memory spaces
723
724 encodeULEB128(0, getStream()); // flags
725 encodeULEB128(NumPages, getStream()); // initial
726
727 endSection(Section);
728}
729
Sam Clegg7c395942017-09-14 23:07:53 +0000730void WasmObjectWriter::writeGlobalSection() {
Sam Clegg9e15f352017-06-03 02:01:24 +0000731 if (Globals.empty())
732 return;
733
734 SectionBookkeeping Section;
735 startSection(Section, wasm::WASM_SEC_GLOBAL);
736
737 encodeULEB128(Globals.size(), getStream());
738 for (const WasmGlobal &Global : Globals) {
739 writeValueType(Global.Type);
740 write8(Global.IsMutable);
741
742 if (Global.HasImport) {
743 assert(Global.InitialValue == 0);
744 write8(wasm::WASM_OPCODE_GET_GLOBAL);
745 encodeULEB128(Global.ImportIndex, getStream());
746 } else {
747 assert(Global.ImportIndex == 0);
748 write8(wasm::WASM_OPCODE_I32_CONST);
749 encodeSLEB128(Global.InitialValue, getStream()); // offset
750 }
751 write8(wasm::WASM_OPCODE_END);
752 }
753
754 endSection(Section);
755}
756
Sam Clegg457fb0b2017-09-15 19:50:44 +0000757void WasmObjectWriter::writeExportSection(ArrayRef<WasmExport> Exports) {
Sam Clegg9e15f352017-06-03 02:01:24 +0000758 if (Exports.empty())
759 return;
760
761 SectionBookkeeping Section;
762 startSection(Section, wasm::WASM_SEC_EXPORT);
763
764 encodeULEB128(Exports.size(), getStream());
765 for (const WasmExport &Export : Exports) {
Sam Cleggb7787fd2017-06-20 04:04:59 +0000766 writeString(Export.FieldName);
Sam Clegg9e15f352017-06-03 02:01:24 +0000767 encodeSLEB128(Export.Kind, getStream());
Sam Clegg9e15f352017-06-03 02:01:24 +0000768 encodeULEB128(Export.Index, getStream());
769 }
770
771 endSection(Section);
772}
773
Sam Clegg457fb0b2017-09-15 19:50:44 +0000774void WasmObjectWriter::writeElemSection(ArrayRef<uint32_t> TableElems) {
Sam Clegg9e15f352017-06-03 02:01:24 +0000775 if (TableElems.empty())
776 return;
777
778 SectionBookkeeping Section;
779 startSection(Section, wasm::WASM_SEC_ELEM);
780
781 encodeULEB128(1, getStream()); // number of "segments"
782 encodeULEB128(0, getStream()); // the table index
783
784 // init expr for starting offset
785 write8(wasm::WASM_OPCODE_I32_CONST);
786 encodeSLEB128(0, getStream());
787 write8(wasm::WASM_OPCODE_END);
788
789 encodeULEB128(TableElems.size(), getStream());
790 for (uint32_t Elem : TableElems)
791 encodeULEB128(Elem, getStream());
792
793 endSection(Section);
794}
795
Sam Clegg457fb0b2017-09-15 19:50:44 +0000796void WasmObjectWriter::writeCodeSection(const MCAssembler &Asm,
797 const MCAsmLayout &Layout,
798 ArrayRef<WasmFunction> Functions) {
Sam Clegg9e15f352017-06-03 02:01:24 +0000799 if (Functions.empty())
800 return;
801
802 SectionBookkeeping Section;
803 startSection(Section, wasm::WASM_SEC_CODE);
804
805 encodeULEB128(Functions.size(), getStream());
806
807 for (const WasmFunction &Func : Functions) {
Sam Cleggfe6414b2017-06-21 23:46:41 +0000808 auto &FuncSection = static_cast<MCSectionWasm &>(Func.Sym->getSection());
Sam Clegg9e15f352017-06-03 02:01:24 +0000809
Sam Clegg9e15f352017-06-03 02:01:24 +0000810 int64_t Size = 0;
811 if (!Func.Sym->getSize()->evaluateAsAbsolute(Size, Layout))
812 report_fatal_error(".size expression must be evaluatable");
813
814 encodeULEB128(Size, getStream());
Sam Cleggfe6414b2017-06-21 23:46:41 +0000815 FuncSection.setSectionOffset(getStream().tell() - Section.ContentsOffset);
Sam Clegg9e15f352017-06-03 02:01:24 +0000816 Asm.writeSectionData(&FuncSection, Layout);
817 }
818
Sam Clegg9e15f352017-06-03 02:01:24 +0000819 // Apply fixups.
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000820 applyRelocations(CodeRelocations, Section.ContentsOffset);
Sam Clegg9e15f352017-06-03 02:01:24 +0000821
822 endSection(Section);
823}
824
Sam Clegg457fb0b2017-09-15 19:50:44 +0000825void WasmObjectWriter::writeDataSection(ArrayRef<WasmDataSegment> Segments) {
Sam Clegg7c395942017-09-14 23:07:53 +0000826 if (Segments.empty())
827 return;
Sam Clegg9e15f352017-06-03 02:01:24 +0000828
829 SectionBookkeeping Section;
830 startSection(Section, wasm::WASM_SEC_DATA);
831
Sam Clegg7c395942017-09-14 23:07:53 +0000832 encodeULEB128(Segments.size(), getStream()); // count
833
834 for (const WasmDataSegment & Segment : Segments) {
835 encodeULEB128(0, getStream()); // memory index
836 write8(wasm::WASM_OPCODE_I32_CONST);
837 encodeSLEB128(Segment.Offset, getStream()); // offset
838 write8(wasm::WASM_OPCODE_END);
839 encodeULEB128(Segment.Data.size(), getStream()); // size
840 Segment.Section->setSectionOffset(getStream().tell() - Section.ContentsOffset);
841 writeBytes(Segment.Data); // data
842 }
Sam Clegg9e15f352017-06-03 02:01:24 +0000843
844 // Apply fixups.
Sam Clegg7c395942017-09-14 23:07:53 +0000845 applyRelocations(DataRelocations, Section.ContentsOffset);
Sam Clegg9e15f352017-06-03 02:01:24 +0000846
847 endSection(Section);
Sam Clegg9e15f352017-06-03 02:01:24 +0000848}
849
850void WasmObjectWriter::writeNameSection(
Sam Clegg457fb0b2017-09-15 19:50:44 +0000851 ArrayRef<WasmFunction> Functions,
852 ArrayRef<WasmImport> Imports,
Sam Clegg9e15f352017-06-03 02:01:24 +0000853 unsigned NumFuncImports) {
854 uint32_t TotalFunctions = NumFuncImports + Functions.size();
855 if (TotalFunctions == 0)
856 return;
857
858 SectionBookkeeping Section;
859 startSection(Section, wasm::WASM_SEC_CUSTOM, "name");
860 SectionBookkeeping SubSection;
861 startSection(SubSection, wasm::WASM_NAMES_FUNCTION);
862
863 encodeULEB128(TotalFunctions, getStream());
864 uint32_t Index = 0;
865 for (const WasmImport &Import : Imports) {
866 if (Import.Kind == wasm::WASM_EXTERNAL_FUNCTION) {
867 encodeULEB128(Index, getStream());
Sam Cleggb7787fd2017-06-20 04:04:59 +0000868 writeString(Import.FieldName);
Sam Clegg9e15f352017-06-03 02:01:24 +0000869 ++Index;
870 }
871 }
872 for (const WasmFunction &Func : Functions) {
873 encodeULEB128(Index, getStream());
Sam Cleggb7787fd2017-06-20 04:04:59 +0000874 writeString(Func.Sym->getName());
Sam Clegg9e15f352017-06-03 02:01:24 +0000875 ++Index;
876 }
877
878 endSection(SubSection);
879 endSection(Section);
880}
881
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000882void WasmObjectWriter::writeCodeRelocSection() {
Sam Clegg9e15f352017-06-03 02:01:24 +0000883 // See: https://github.com/WebAssembly/tool-conventions/blob/master/Linking.md
884 // for descriptions of the reloc sections.
885
886 if (CodeRelocations.empty())
887 return;
888
889 SectionBookkeeping Section;
890 startSection(Section, wasm::WASM_SEC_CUSTOM, "reloc.CODE");
891
892 encodeULEB128(wasm::WASM_SEC_CODE, getStream());
Sam Cleggacd7d2b2017-06-06 19:15:05 +0000893 encodeULEB128(CodeRelocations.size(), getStream());
Sam Clegg9e15f352017-06-03 02:01:24 +0000894
Sam Clegg7c395942017-09-14 23:07:53 +0000895 writeRelocations(CodeRelocations);
Sam Clegg9e15f352017-06-03 02:01:24 +0000896
897 endSection(Section);
898}
899
Sam Clegg7c395942017-09-14 23:07:53 +0000900void WasmObjectWriter::writeDataRelocSection() {
Sam Clegg9e15f352017-06-03 02:01:24 +0000901 // See: https://github.com/WebAssembly/tool-conventions/blob/master/Linking.md
902 // for descriptions of the reloc sections.
903
904 if (DataRelocations.empty())
905 return;
906
907 SectionBookkeeping Section;
908 startSection(Section, wasm::WASM_SEC_CUSTOM, "reloc.DATA");
909
910 encodeULEB128(wasm::WASM_SEC_DATA, getStream());
911 encodeULEB128(DataRelocations.size(), getStream());
912
Sam Clegg7c395942017-09-14 23:07:53 +0000913 writeRelocations(DataRelocations);
Sam Clegg9e15f352017-06-03 02:01:24 +0000914
915 endSection(Section);
916}
917
918void WasmObjectWriter::writeLinkingMetaDataSection(
Sam Cleggd95ed952017-09-20 19:03:35 +0000919 ArrayRef<WasmDataSegment> Segments, uint32_t DataSize,
Sam Clegg31a2c802017-09-20 21:17:04 +0000920 SmallVector<std::pair<StringRef, uint32_t>, 4> SymbolFlags,
Sam Clegg9e1ade92017-06-27 20:27:59 +0000921 bool HasStackPointer, uint32_t StackPointerGlobal) {
Sam Clegg9e15f352017-06-03 02:01:24 +0000922 SectionBookkeeping Section;
923 startSection(Section, wasm::WASM_SEC_CUSTOM, "linking");
Sam Cleggb7787fd2017-06-20 04:04:59 +0000924 SectionBookkeeping SubSection;
Sam Clegg9e15f352017-06-03 02:01:24 +0000925
Sam Cleggb7787fd2017-06-20 04:04:59 +0000926 if (HasStackPointer) {
927 startSection(SubSection, wasm::WASM_STACK_POINTER);
928 encodeULEB128(StackPointerGlobal, getStream()); // id
929 endSection(SubSection);
930 }
Sam Clegg9e15f352017-06-03 02:01:24 +0000931
Sam Clegg31a2c802017-09-20 21:17:04 +0000932 if (SymbolFlags.size() != 0) {
Sam Cleggb7787fd2017-06-20 04:04:59 +0000933 startSection(SubSection, wasm::WASM_SYMBOL_INFO);
Sam Clegg31a2c802017-09-20 21:17:04 +0000934 encodeULEB128(SymbolFlags.size(), getStream());
935 for (auto Pair: SymbolFlags) {
936 writeString(Pair.first);
937 encodeULEB128(Pair.second, getStream());
Sam Cleggb7787fd2017-06-20 04:04:59 +0000938 }
939 endSection(SubSection);
940 }
Sam Clegg9e15f352017-06-03 02:01:24 +0000941
Sam Clegg9e1ade92017-06-27 20:27:59 +0000942 if (DataSize > 0) {
943 startSection(SubSection, wasm::WASM_DATA_SIZE);
944 encodeULEB128(DataSize, getStream());
945 endSection(SubSection);
Sam Clegg9e1ade92017-06-27 20:27:59 +0000946 }
947
Sam Cleggd95ed952017-09-20 19:03:35 +0000948 if (Segments.size()) {
Sam Clegg63ebb812017-09-29 16:50:08 +0000949 startSection(SubSection, wasm::WASM_SEGMENT_INFO);
Sam Cleggd95ed952017-09-20 19:03:35 +0000950 encodeULEB128(Segments.size(), getStream());
Sam Clegg63ebb812017-09-29 16:50:08 +0000951 for (const WasmDataSegment &Segment : Segments) {
Sam Cleggd95ed952017-09-20 19:03:35 +0000952 writeString(Segment.Name);
Sam Clegg63ebb812017-09-29 16:50:08 +0000953 encodeULEB128(Segment.Alignment, getStream());
954 encodeULEB128(Segment.Flags, getStream());
955 }
Sam Cleggd95ed952017-09-20 19:03:35 +0000956 endSection(SubSection);
957 }
958
Sam Clegg9e15f352017-06-03 02:01:24 +0000959 endSection(Section);
960}
961
Sam Clegg5e3d33a2017-07-07 02:01:29 +0000962uint32_t WasmObjectWriter::getFunctionType(const MCSymbolWasm& Symbol) {
963 assert(Symbol.isFunction());
964 assert(TypeIndices.count(&Symbol));
965 return TypeIndices[&Symbol];
966}
967
968uint32_t WasmObjectWriter::registerFunctionType(const MCSymbolWasm& Symbol) {
969 assert(Symbol.isFunction());
970
971 WasmFunctionType F;
Sam Cleggaff1c4d2017-09-15 19:22:01 +0000972 const MCSymbolWasm* ResolvedSym = ResolveSymbol(Symbol);
973 F.Returns = ResolvedSym->getReturns();
974 F.Params = ResolvedSym->getParams();
Sam Clegg5e3d33a2017-07-07 02:01:29 +0000975
976 auto Pair =
977 FunctionTypeIndices.insert(std::make_pair(F, FunctionTypes.size()));
978 if (Pair.second)
979 FunctionTypes.push_back(F);
980 TypeIndices[&Symbol] = Pair.first->second;
981
982 DEBUG(dbgs() << "registerFunctionType: " << Symbol << " new:" << Pair.second << "\n");
983 DEBUG(dbgs() << " -> type index: " << Pair.first->second << "\n");
984 return Pair.first->second;
985}
986
Dan Gohman18eafb62017-02-22 01:23:18 +0000987void WasmObjectWriter::writeObject(MCAssembler &Asm,
988 const MCAsmLayout &Layout) {
Sam Cleggb7787fd2017-06-20 04:04:59 +0000989 DEBUG(dbgs() << "WasmObjectWriter::writeObject\n");
Dan Gohman82607f52017-02-24 23:46:05 +0000990 MCContext &Ctx = Asm.getContext();
Derek Schuffb8795392017-03-16 20:49:48 +0000991 wasm::ValType PtrType = is64Bit() ? wasm::ValType::I64 : wasm::ValType::I32;
Dan Gohmand934cb82017-02-24 23:18:00 +0000992
993 // Collect information from the available symbols.
Dan Gohmand934cb82017-02-24 23:18:00 +0000994 SmallVector<WasmFunction, 4> Functions;
995 SmallVector<uint32_t, 4> TableElems;
Dan Gohmand934cb82017-02-24 23:18:00 +0000996 SmallVector<WasmImport, 4> Imports;
997 SmallVector<WasmExport, 4> Exports;
Sam Clegg31a2c802017-09-20 21:17:04 +0000998 SmallVector<std::pair<StringRef, uint32_t>, 4> SymbolFlags;
Dan Gohmand934cb82017-02-24 23:18:00 +0000999 SmallPtrSet<const MCSymbolWasm *, 4> IsAddressTaken;
1000 unsigned NumFuncImports = 0;
Sam Clegg7c395942017-09-14 23:07:53 +00001001 SmallVector<WasmDataSegment, 4> DataSegments;
Dan Gohman970d02c2017-03-30 23:58:19 +00001002 uint32_t StackPointerGlobal = 0;
Sam Clegg7c395942017-09-14 23:07:53 +00001003 uint32_t DataSize = 0;
Dan Gohman970d02c2017-03-30 23:58:19 +00001004 bool HasStackPointer = false;
Dan Gohmand934cb82017-02-24 23:18:00 +00001005
1006 // Populate the IsAddressTaken set.
Sam Cleggb7787fd2017-06-20 04:04:59 +00001007 for (const WasmRelocationEntry &RelEntry : CodeRelocations) {
Dan Gohmand934cb82017-02-24 23:18:00 +00001008 switch (RelEntry.Type) {
1009 case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
Sam Clegg13a2e892017-09-01 17:32:01 +00001010 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
Dan Gohmand934cb82017-02-24 23:18:00 +00001011 IsAddressTaken.insert(RelEntry.Symbol);
1012 break;
1013 default:
1014 break;
1015 }
1016 }
Sam Cleggb7787fd2017-06-20 04:04:59 +00001017 for (const WasmRelocationEntry &RelEntry : DataRelocations) {
Dan Gohmand934cb82017-02-24 23:18:00 +00001018 switch (RelEntry.Type) {
1019 case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32:
Sam Clegg13a2e892017-09-01 17:32:01 +00001020 case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32:
Dan Gohmand934cb82017-02-24 23:18:00 +00001021 IsAddressTaken.insert(RelEntry.Symbol);
1022 break;
1023 default:
1024 break;
1025 }
1026 }
1027
Sam Clegg7c395942017-09-14 23:07:53 +00001028 // Populate FunctionTypeIndices and Imports.
Dan Gohmand934cb82017-02-24 23:18:00 +00001029 for (const MCSymbol &S : Asm.symbols()) {
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001030 const auto &WS = static_cast<const MCSymbolWasm &>(S);
1031
1032 if (WS.isTemporary())
Sam Clegg8c4baa002017-07-05 20:09:26 +00001033 continue;
1034
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001035 if (WS.isFunction())
1036 registerFunctionType(WS);
Dan Gohmand934cb82017-02-24 23:18:00 +00001037
1038 // If the symbol is not defined in this translation unit, import it.
Sam Cleggba9fa9f2017-09-26 21:10:09 +00001039 if (!WS.isDefined(/*SetUsed=*/false)) {
Dan Gohmand934cb82017-02-24 23:18:00 +00001040 WasmImport Import;
1041 Import.ModuleName = WS.getModuleName();
1042 Import.FieldName = WS.getName();
1043
1044 if (WS.isFunction()) {
1045 Import.Kind = wasm::WASM_EXTERNAL_FUNCTION;
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001046 Import.Type = getFunctionType(WS);
Dan Gohmand934cb82017-02-24 23:18:00 +00001047 SymbolIndices[&WS] = NumFuncImports;
1048 ++NumFuncImports;
1049 } else {
1050 Import.Kind = wasm::WASM_EXTERNAL_GLOBAL;
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001051 Import.Type = int32_t(PtrType);
Dan Gohmand934cb82017-02-24 23:18:00 +00001052 SymbolIndices[&WS] = NumGlobalImports;
1053 ++NumGlobalImports;
1054 }
1055
1056 Imports.push_back(Import);
1057 }
1058 }
1059
Dan Gohman82607f52017-02-24 23:46:05 +00001060 // In the special .global_variables section, we've encoded global
1061 // variables used by the function. Translate them into the Globals
1062 // list.
Sam Clegg759631c2017-09-15 20:54:59 +00001063 MCSectionWasm *GlobalVars = Ctx.getWasmSection(".global_variables", wasm::WASM_SEC_DATA);
Dan Gohman82607f52017-02-24 23:46:05 +00001064 if (!GlobalVars->getFragmentList().empty()) {
1065 if (GlobalVars->getFragmentList().size() != 1)
1066 report_fatal_error("only one .global_variables fragment supported");
1067 const MCFragment &Frag = *GlobalVars->begin();
1068 if (Frag.hasInstructions() || Frag.getKind() != MCFragment::FT_Data)
1069 report_fatal_error("only data supported in .global_variables");
Sam Cleggfe6414b2017-06-21 23:46:41 +00001070 const auto &DataFrag = cast<MCDataFragment>(Frag);
Dan Gohman82607f52017-02-24 23:46:05 +00001071 if (!DataFrag.getFixups().empty())
1072 report_fatal_error("fixups not supported in .global_variables");
1073 const SmallVectorImpl<char> &Contents = DataFrag.getContents();
Dan Gohman970d02c2017-03-30 23:58:19 +00001074 for (const uint8_t *p = (const uint8_t *)Contents.data(),
1075 *end = (const uint8_t *)Contents.data() + Contents.size();
1076 p != end; ) {
Dan Gohman82607f52017-02-24 23:46:05 +00001077 WasmGlobal G;
Dan Gohman970d02c2017-03-30 23:58:19 +00001078 if (end - p < 3)
1079 report_fatal_error("truncated global variable encoding");
1080 G.Type = wasm::ValType(int8_t(*p++));
1081 G.IsMutable = bool(*p++);
1082 G.HasImport = bool(*p++);
1083 if (G.HasImport) {
1084 G.InitialValue = 0;
1085
1086 WasmImport Import;
1087 Import.ModuleName = (const char *)p;
1088 const uint8_t *nul = (const uint8_t *)memchr(p, '\0', end - p);
1089 if (!nul)
1090 report_fatal_error("global module name must be nul-terminated");
1091 p = nul + 1;
1092 nul = (const uint8_t *)memchr(p, '\0', end - p);
1093 if (!nul)
1094 report_fatal_error("global base name must be nul-terminated");
1095 Import.FieldName = (const char *)p;
1096 p = nul + 1;
1097
1098 Import.Kind = wasm::WASM_EXTERNAL_GLOBAL;
1099 Import.Type = int32_t(G.Type);
1100
1101 G.ImportIndex = NumGlobalImports;
1102 ++NumGlobalImports;
1103
1104 Imports.push_back(Import);
1105 } else {
1106 unsigned n;
1107 G.InitialValue = decodeSLEB128(p, &n);
1108 G.ImportIndex = 0;
Simon Pilgrimc8da0c02017-03-31 10:45:35 +00001109 if ((ptrdiff_t)n > end - p)
Dan Gohman970d02c2017-03-30 23:58:19 +00001110 report_fatal_error("global initial value must be valid SLEB128");
1111 p += n;
1112 }
Dan Gohman82607f52017-02-24 23:46:05 +00001113 Globals.push_back(G);
1114 }
1115 }
1116
Dan Gohman970d02c2017-03-30 23:58:19 +00001117 // In the special .stack_pointer section, we've encoded the stack pointer
1118 // index.
Sam Clegg759631c2017-09-15 20:54:59 +00001119 MCSectionWasm *StackPtr = Ctx.getWasmSection(".stack_pointer", wasm::WASM_SEC_DATA);
Dan Gohman970d02c2017-03-30 23:58:19 +00001120 if (!StackPtr->getFragmentList().empty()) {
1121 if (StackPtr->getFragmentList().size() != 1)
1122 report_fatal_error("only one .stack_pointer fragment supported");
1123 const MCFragment &Frag = *StackPtr->begin();
1124 if (Frag.hasInstructions() || Frag.getKind() != MCFragment::FT_Data)
1125 report_fatal_error("only data supported in .stack_pointer");
Sam Cleggfe6414b2017-06-21 23:46:41 +00001126 const auto &DataFrag = cast<MCDataFragment>(Frag);
Dan Gohman970d02c2017-03-30 23:58:19 +00001127 if (!DataFrag.getFixups().empty())
1128 report_fatal_error("fixups not supported in .stack_pointer");
1129 const SmallVectorImpl<char> &Contents = DataFrag.getContents();
1130 if (Contents.size() != 4)
1131 report_fatal_error("only one entry supported in .stack_pointer");
1132 HasStackPointer = true;
1133 StackPointerGlobal = NumGlobalImports + *(const int32_t *)Contents.data();
1134 }
1135
Sam Clegg759631c2017-09-15 20:54:59 +00001136 for (MCSection &Sec : Asm) {
1137 auto &Section = static_cast<MCSectionWasm &>(Sec);
1138 if (Section.getType() != wasm::WASM_SEC_DATA)
1139 continue;
1140
1141 DataSize = alignTo(DataSize, Section.getAlignment());
1142 DataSegments.emplace_back();
1143 WasmDataSegment &Segment = DataSegments.back();
Sam Cleggd95ed952017-09-20 19:03:35 +00001144 Segment.Name = Section.getSectionName();
Sam Clegg759631c2017-09-15 20:54:59 +00001145 Segment.Offset = DataSize;
1146 Segment.Section = &Section;
Sam Clegg63ebb812017-09-29 16:50:08 +00001147 addData(Segment.Data, Section);
1148 Segment.Alignment = Section.getAlignment();
1149 Segment.Flags = 0;
Sam Clegg759631c2017-09-15 20:54:59 +00001150 DataSize += Segment.Data.size();
1151 Section.setMemoryOffset(Segment.Offset);
1152 }
1153
Sam Cleggb7787fd2017-06-20 04:04:59 +00001154 // Handle regular defined and undefined symbols.
Dan Gohmand934cb82017-02-24 23:18:00 +00001155 for (const MCSymbol &S : Asm.symbols()) {
1156 // Ignore unnamed temporary symbols, which aren't ever exported, imported,
1157 // or used in relocations.
1158 if (S.isTemporary() && S.getName().empty())
1159 continue;
Sam Cleggb7787fd2017-06-20 04:04:59 +00001160
Dan Gohmand934cb82017-02-24 23:18:00 +00001161 const auto &WS = static_cast<const MCSymbolWasm &>(S);
Sam Cleggb7787fd2017-06-20 04:04:59 +00001162 DEBUG(dbgs() << "MCSymbol: '" << S << "'"
1163 << " isDefined=" << S.isDefined() << " isExternal="
1164 << S.isExternal() << " isTemporary=" << S.isTemporary()
1165 << " isFunction=" << WS.isFunction()
1166 << " isWeak=" << WS.isWeak()
1167 << " isVariable=" << WS.isVariable() << "\n");
1168
1169 if (WS.isWeak())
Sam Clegg31a2c802017-09-20 21:17:04 +00001170 SymbolFlags.emplace_back(WS.getName(), wasm::WASM_SYMBOL_BINDING_WEAK);
Sam Cleggb7787fd2017-06-20 04:04:59 +00001171
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001172 if (WS.isVariable())
1173 continue;
1174
Dan Gohmand934cb82017-02-24 23:18:00 +00001175 unsigned Index;
Sam Cleggb7787fd2017-06-20 04:04:59 +00001176
Dan Gohmand934cb82017-02-24 23:18:00 +00001177 if (WS.isFunction()) {
Dan Gohmand934cb82017-02-24 23:18:00 +00001178 if (WS.isDefined(/*SetUsed=*/false)) {
Sam Cleggb7787fd2017-06-20 04:04:59 +00001179 if (WS.getOffset() != 0)
1180 report_fatal_error(
1181 "function sections must contain one function each");
1182
1183 if (WS.getSize() == 0)
1184 report_fatal_error(
1185 "function symbols must have a size set with .size");
1186
Dan Gohmand934cb82017-02-24 23:18:00 +00001187 // A definition. Take the next available index.
1188 Index = NumFuncImports + Functions.size();
1189
1190 // Prepare the function.
1191 WasmFunction Func;
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001192 Func.Type = getFunctionType(WS);
Dan Gohmand934cb82017-02-24 23:18:00 +00001193 Func.Sym = &WS;
1194 SymbolIndices[&WS] = Index;
1195 Functions.push_back(Func);
1196 } else {
1197 // An import; the index was assigned above.
1198 Index = SymbolIndices.find(&WS)->second;
1199 }
1200
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001201 DEBUG(dbgs() << " -> function index: " << Index << "\n");
1202
Dan Gohmand934cb82017-02-24 23:18:00 +00001203 // If needed, prepare the function to be called indirectly.
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001204 if (IsAddressTaken.count(&WS) != 0) {
Sam Cleggd99f6072017-06-12 23:52:44 +00001205 IndirectSymbolIndices[&WS] = TableElems.size();
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001206 DEBUG(dbgs() << " -> adding to table: " << TableElems.size() << "\n");
Dan Gohmand934cb82017-02-24 23:18:00 +00001207 TableElems.push_back(Index);
Sam Cleggd99f6072017-06-12 23:52:44 +00001208 }
Dan Gohmand934cb82017-02-24 23:18:00 +00001209 } else {
Sam Cleggc38e9472017-06-02 01:05:24 +00001210 if (WS.isTemporary() && !WS.getSize())
1211 continue;
Dan Gohmand934cb82017-02-24 23:18:00 +00001212
Sam Cleggfe6414b2017-06-21 23:46:41 +00001213 if (!WS.isDefined(/*SetUsed=*/false))
1214 continue;
Sam Cleggc38e9472017-06-02 01:05:24 +00001215
Sam Cleggfe6414b2017-06-21 23:46:41 +00001216 if (!WS.getSize())
1217 report_fatal_error("data symbols must have a size set with .size: " +
1218 WS.getName());
Sam Cleggc38e9472017-06-02 01:05:24 +00001219
Sam Cleggfe6414b2017-06-21 23:46:41 +00001220 int64_t Size = 0;
1221 if (!WS.getSize()->evaluateAsAbsolute(Size, Layout))
1222 report_fatal_error(".size expression must be evaluatable");
Dan Gohmand934cb82017-02-24 23:18:00 +00001223
Sam Clegg7c395942017-09-14 23:07:53 +00001224 // For each global, prepare a corresponding wasm global holding its
1225 // address. For externals these will also be named exports.
1226 Index = NumGlobalImports + Globals.size();
Sam Clegg759631c2017-09-15 20:54:59 +00001227 auto &DataSection = static_cast<MCSectionWasm &>(WS.getSection());
Sam Clegg7c395942017-09-14 23:07:53 +00001228
1229 WasmGlobal Global;
1230 Global.Type = PtrType;
1231 Global.IsMutable = false;
1232 Global.HasImport = false;
Sam Clegg759631c2017-09-15 20:54:59 +00001233 Global.InitialValue = DataSection.getMemoryOffset() + Layout.getSymbolOffset(WS);
Sam Clegg7c395942017-09-14 23:07:53 +00001234 Global.ImportIndex = 0;
1235 SymbolIndices[&WS] = Index;
1236 DEBUG(dbgs() << " -> global index: " << Index << "\n");
1237 Globals.push_back(Global);
Dan Gohmand934cb82017-02-24 23:18:00 +00001238 }
1239
1240 // If the symbol is visible outside this translation unit, export it.
Sam Clegg31a2c802017-09-20 21:17:04 +00001241 if (WS.isDefined(/*SetUsed=*/false)) {
Dan Gohmand934cb82017-02-24 23:18:00 +00001242 WasmExport Export;
1243 Export.FieldName = WS.getName();
1244 Export.Index = Index;
Dan Gohmand934cb82017-02-24 23:18:00 +00001245 if (WS.isFunction())
1246 Export.Kind = wasm::WASM_EXTERNAL_FUNCTION;
1247 else
1248 Export.Kind = wasm::WASM_EXTERNAL_GLOBAL;
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001249 DEBUG(dbgs() << " -> export " << Exports.size() << "\n");
Dan Gohmand934cb82017-02-24 23:18:00 +00001250 Exports.push_back(Export);
Sam Clegg31a2c802017-09-20 21:17:04 +00001251 if (!WS.isExternal())
1252 SymbolFlags.emplace_back(WS.getName(), wasm::WASM_SYMBOL_BINDING_LOCAL);
Dan Gohmand934cb82017-02-24 23:18:00 +00001253 }
1254 }
1255
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001256 // Handle weak aliases. We need to process these in a separate pass because
1257 // we need to have processed the target of the alias before the alias itself
1258 // and the symbols are not necessarily ordered in this way.
Sam Cleggb7787fd2017-06-20 04:04:59 +00001259 for (const MCSymbol &S : Asm.symbols()) {
1260 if (!S.isVariable())
1261 continue;
Sam Clegg31a2c802017-09-20 21:17:04 +00001262
Sam Cleggb7787fd2017-06-20 04:04:59 +00001263 assert(S.isDefined(/*SetUsed=*/false));
1264
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001265 // Find the target symbol of this weak alias and export that index
Sam Cleggaff1c4d2017-09-15 19:22:01 +00001266 const auto &WS = static_cast<const MCSymbolWasm &>(S);
1267 const MCSymbolWasm *ResolvedSym = ResolveSymbol(WS);
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001268 DEBUG(dbgs() << WS.getName() << ": weak alias of '" << *ResolvedSym << "'\n");
1269 assert(SymbolIndices.count(ResolvedSym) > 0);
Sam Cleggb7787fd2017-06-20 04:04:59 +00001270 uint32_t Index = SymbolIndices.find(ResolvedSym)->second;
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001271 DEBUG(dbgs() << " -> index:" << Index << "\n");
Sam Cleggb7787fd2017-06-20 04:04:59 +00001272
Sam Cleggba9fa9f2017-09-26 21:10:09 +00001273 SymbolIndices[&WS] = Index;
Sam Cleggb7787fd2017-06-20 04:04:59 +00001274 WasmExport Export;
1275 Export.FieldName = WS.getName();
1276 Export.Index = Index;
1277 if (WS.isFunction())
1278 Export.Kind = wasm::WASM_EXTERNAL_FUNCTION;
1279 else
1280 Export.Kind = wasm::WASM_EXTERNAL_GLOBAL;
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001281 DEBUG(dbgs() << " -> export " << Exports.size() << "\n");
Sam Cleggb7787fd2017-06-20 04:04:59 +00001282 Exports.push_back(Export);
Sam Clegg31a2c802017-09-20 21:17:04 +00001283
1284 if (!WS.isExternal())
1285 SymbolFlags.emplace_back(WS.getName(), wasm::WASM_SYMBOL_BINDING_LOCAL);
Sam Cleggb7787fd2017-06-20 04:04:59 +00001286 }
1287
Dan Gohmand934cb82017-02-24 23:18:00 +00001288 // Add types for indirect function calls.
Sam Cleggacd7d2b2017-06-06 19:15:05 +00001289 for (const WasmRelocationEntry &Fixup : CodeRelocations) {
1290 if (Fixup.Type != wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB)
1291 continue;
Dan Gohman970d02c2017-03-30 23:58:19 +00001292
Sam Clegg5e3d33a2017-07-07 02:01:29 +00001293 registerFunctionType(*Fixup.Symbol);
Dan Gohmand934cb82017-02-24 23:18:00 +00001294 }
1295
Dan Gohman18eafb62017-02-22 01:23:18 +00001296 // Write out the Wasm header.
1297 writeHeader(Asm);
1298
Sam Clegg9e15f352017-06-03 02:01:24 +00001299 writeTypeSection(FunctionTypes);
1300 writeImportSection(Imports);
1301 writeFunctionSection(Functions);
Sam Cleggd99f6072017-06-12 23:52:44 +00001302 writeTableSection(TableElems.size());
Sam Clegg7c395942017-09-14 23:07:53 +00001303 writeMemorySection(DataSize);
1304 writeGlobalSection();
Sam Clegg9e15f352017-06-03 02:01:24 +00001305 writeExportSection(Exports);
1306 // TODO: Start Section
1307 writeElemSection(TableElems);
Sam Cleggacd7d2b2017-06-06 19:15:05 +00001308 writeCodeSection(Asm, Layout, Functions);
Sam Clegg7c395942017-09-14 23:07:53 +00001309 writeDataSection(DataSegments);
Sam Clegg9e15f352017-06-03 02:01:24 +00001310 writeNameSection(Functions, Imports, NumFuncImports);
Sam Cleggacd7d2b2017-06-06 19:15:05 +00001311 writeCodeRelocSection();
Sam Clegg7c395942017-09-14 23:07:53 +00001312 writeDataRelocSection();
Sam Clegg63ebb812017-09-29 16:50:08 +00001313 writeLinkingMetaDataSection(DataSegments, DataSize, SymbolFlags,
1314 HasStackPointer, StackPointerGlobal);
Dan Gohman970d02c2017-03-30 23:58:19 +00001315
Dan Gohmand934cb82017-02-24 23:18:00 +00001316 // TODO: Translate the .comment section to the output.
Dan Gohmand934cb82017-02-24 23:18:00 +00001317 // TODO: Translate debug sections to the output.
Dan Gohman18eafb62017-02-22 01:23:18 +00001318}
1319
Lang Hames60fbc7c2017-10-10 16:28:07 +00001320std::unique_ptr<MCObjectWriter>
Lang Hames1301a872017-10-10 01:15:10 +00001321llvm::createWasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW,
1322 raw_pwrite_stream &OS) {
Lang Hames60fbc7c2017-10-10 16:28:07 +00001323 // FIXME: Can't use make_unique<WasmObjectWriter>(...) as WasmObjectWriter's
1324 // destructor is private. Is that necessary?
1325 return std::unique_ptr<MCObjectWriter>(
1326 new WasmObjectWriter(std::move(MOTW), OS));
Dan Gohman18eafb62017-02-22 01:23:18 +00001327}