1 //===-- WebAssemblyAsmPrinter.cpp - WebAssembly LLVM assembly writer ------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 ///
9 /// \file
10 /// This file contains a printer that converts from our internal
11 /// representation of machine-dependent LLVM code to the WebAssembly assembly
12 /// language.
13 ///
14 //===----------------------------------------------------------------------===//
15
16 #include "WebAssemblyAsmPrinter.h"
17 #include "MCTargetDesc/WebAssemblyInstPrinter.h"
18 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
19 #include "MCTargetDesc/WebAssemblyTargetStreamer.h"
20 #include "TargetInfo/WebAssemblyTargetInfo.h"
21 #include "WebAssembly.h"
22 #include "WebAssemblyMCInstLower.h"
23 #include "WebAssemblyMachineFunctionInfo.h"
24 #include "WebAssemblyRegisterInfo.h"
25 #include "WebAssemblyTargetMachine.h"
26 #include "llvm/ADT/SmallSet.h"
27 #include "llvm/ADT/StringExtras.h"
28 #include "llvm/BinaryFormat/Wasm.h"
29 #include "llvm/CodeGen/Analysis.h"
30 #include "llvm/CodeGen/AsmPrinter.h"
31 #include "llvm/CodeGen/MachineConstantPool.h"
32 #include "llvm/CodeGen/MachineInstr.h"
33 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
34 #include "llvm/IR/DataLayout.h"
35 #include "llvm/IR/DebugInfoMetadata.h"
36 #include "llvm/IR/GlobalVariable.h"
37 #include "llvm/IR/Metadata.h"
38 #include "llvm/MC/MCContext.h"
39 #include "llvm/MC/MCSectionWasm.h"
40 #include "llvm/MC/MCStreamer.h"
41 #include "llvm/MC/MCSymbol.h"
42 #include "llvm/MC/MCSymbolWasm.h"
43 #include "llvm/Support/Debug.h"
44 #include "llvm/Support/TargetRegistry.h"
45 #include "llvm/Support/raw_ostream.h"
46
47 using namespace llvm;
48
49 #define DEBUG_TYPE "asm-printer"
50
51 extern cl::opt<bool> WasmKeepRegisters;
52 extern cl::opt<bool> EnableEmException;
53 extern cl::opt<bool> EnableEmSjLj;
54
55 //===----------------------------------------------------------------------===//
56 // Helpers.
57 //===----------------------------------------------------------------------===//
58
getRegType(unsigned RegNo) const59 MVT WebAssemblyAsmPrinter::getRegType(unsigned RegNo) const {
60 const TargetRegisterInfo *TRI = Subtarget->getRegisterInfo();
61 const TargetRegisterClass *TRC = MRI->getRegClass(RegNo);
62 for (MVT T : {MVT::i32, MVT::i64, MVT::f32, MVT::f64, MVT::v16i8, MVT::v8i16,
63 MVT::v4i32, MVT::v2i64, MVT::v4f32, MVT::v2f64})
64 if (TRI->isTypeLegalForClass(*TRC, T))
65 return T;
66 LLVM_DEBUG(errs() << "Unknown type for register number: " << RegNo);
67 llvm_unreachable("Unknown register type");
68 return MVT::Other;
69 }
70
regToString(const MachineOperand & MO)71 std::string WebAssemblyAsmPrinter::regToString(const MachineOperand &MO) {
72 Register RegNo = MO.getReg();
73 assert(Register::isVirtualRegister(RegNo) &&
74 "Unlowered physical register encountered during assembly printing");
75 assert(!MFI->isVRegStackified(RegNo));
76 unsigned WAReg = MFI->getWAReg(RegNo);
77 assert(WAReg != WebAssemblyFunctionInfo::UnusedReg);
78 return '$' + utostr(WAReg);
79 }
80
getTargetStreamer()81 WebAssemblyTargetStreamer *WebAssemblyAsmPrinter::getTargetStreamer() {
82 MCTargetStreamer *TS = OutStreamer->getTargetStreamer();
83 return static_cast<WebAssemblyTargetStreamer *>(TS);
84 }
85
86 // Emscripten exception handling helpers
87 //
88 // This converts invoke names generated by LowerEmscriptenEHSjLj to real names
89 // that are expected by JavaScript glue code. The invoke names generated by
90 // Emscripten JS glue code are based on their argument and return types; for
91 // example, for a function that takes an i32 and returns nothing, it is
92 // 'invoke_vi'. But the format of invoke generated by LowerEmscriptenEHSjLj pass
93 // contains a mangled string generated from their IR types, for example,
94 // "__invoke_void_%struct.mystruct*_int", because final wasm types are not
95 // available in the IR pass. So we convert those names to the form that
96 // Emscripten JS code expects.
97 //
98 // Refer to LowerEmscriptenEHSjLj pass for more details.
99
100 // Returns true if the given function name is an invoke name generated by
101 // LowerEmscriptenEHSjLj pass.
isEmscriptenInvokeName(StringRef Name)102 static bool isEmscriptenInvokeName(StringRef Name) {
103 if (Name.front() == '"' && Name.back() == '"')
104 Name = Name.substr(1, Name.size() - 2);
105 return Name.startswith("__invoke_");
106 }
107
108 // Returns a character that represents the given wasm value type in invoke
109 // signatures.
getInvokeSig(wasm::ValType VT)110 static char getInvokeSig(wasm::ValType VT) {
111 switch (VT) {
112 case wasm::ValType::I32:
113 return 'i';
114 case wasm::ValType::I64:
115 return 'j';
116 case wasm::ValType::F32:
117 return 'f';
118 case wasm::ValType::F64:
119 return 'd';
120 case wasm::ValType::V128:
121 return 'V';
122 case wasm::ValType::EXNREF:
123 return 'E';
124 case wasm::ValType::FUNCREF:
125 return 'F';
126 case wasm::ValType::EXTERNREF:
127 return 'X';
128 }
129 llvm_unreachable("Unhandled wasm::ValType enum");
130 }
131
132 // Given the wasm signature, generate the invoke name in the format JS glue code
133 // expects.
getEmscriptenInvokeSymbolName(wasm::WasmSignature * Sig)134 static std::string getEmscriptenInvokeSymbolName(wasm::WasmSignature *Sig) {
135 assert(Sig->Returns.size() <= 1);
136 std::string Ret = "invoke_";
137 if (!Sig->Returns.empty())
138 for (auto VT : Sig->Returns)
139 Ret += getInvokeSig(VT);
140 else
141 Ret += 'v';
142 // Invokes' first argument is a pointer to the original function, so skip it
143 for (unsigned I = 1, E = Sig->Params.size(); I < E; I++)
144 Ret += getInvokeSig(Sig->Params[I]);
145 return Ret;
146 }
147
148 //===----------------------------------------------------------------------===//
149 // WebAssemblyAsmPrinter Implementation.
150 //===----------------------------------------------------------------------===//
151
getMCSymbolForFunction(const Function * F,bool EnableEmEH,wasm::WasmSignature * Sig,bool & InvokeDetected)152 MCSymbolWasm *WebAssemblyAsmPrinter::getMCSymbolForFunction(
153 const Function *F, bool EnableEmEH, wasm::WasmSignature *Sig,
154 bool &InvokeDetected) {
155 MCSymbolWasm *WasmSym = nullptr;
156 if (EnableEmEH && isEmscriptenInvokeName(F->getName())) {
157 assert(Sig);
158 InvokeDetected = true;
159 if (Sig->Returns.size() > 1) {
160 std::string Msg =
161 "Emscripten EH/SjLj does not support multivalue returns: " +
162 std::string(F->getName()) + ": " +
163 WebAssembly::signatureToString(Sig);
164 report_fatal_error(Msg);
165 }
166 WasmSym = cast<MCSymbolWasm>(
167 GetExternalSymbolSymbol(getEmscriptenInvokeSymbolName(Sig)));
168 } else {
169 WasmSym = cast<MCSymbolWasm>(getSymbol(F));
170 }
171 return WasmSym;
172 }
173
emitEndOfAsmFile(Module & M)174 void WebAssemblyAsmPrinter::emitEndOfAsmFile(Module &M) {
175 for (auto &It : OutContext.getSymbols()) {
176 // Emit a .globaltype and .eventtype declaration.
177 auto Sym = cast<MCSymbolWasm>(It.getValue());
178 if (Sym->getType() == wasm::WASM_SYMBOL_TYPE_GLOBAL)
179 getTargetStreamer()->emitGlobalType(Sym);
180 else if (Sym->getType() == wasm::WASM_SYMBOL_TYPE_EVENT)
181 getTargetStreamer()->emitEventType(Sym);
182 }
183
184 DenseSet<MCSymbol *> InvokeSymbols;
185 for (const auto &F : M) {
186 if (F.isIntrinsic())
187 continue;
188
189 // Emit function type info for all undefined functions
190 if (F.isDeclarationForLinker()) {
191 SmallVector<MVT, 4> Results;
192 SmallVector<MVT, 4> Params;
193 computeSignatureVTs(F.getFunctionType(), &F, F, TM, Params, Results);
194 // At this point these MCSymbols may or may not have been created already
195 // and thus also contain a signature, but we need to get the signature
196 // anyway here in case it is an invoke that has not yet been created. We
197 // will discard it later if it turns out not to be necessary.
198 auto Signature = signatureFromMVTs(Results, Params);
199 bool InvokeDetected = false;
200 auto *Sym = getMCSymbolForFunction(&F, EnableEmException || EnableEmSjLj,
201 Signature.get(), InvokeDetected);
202
203 // Multiple functions can be mapped to the same invoke symbol. For
204 // example, two IR functions '__invoke_void_i8*' and '__invoke_void_i32'
205 // are both mapped to '__invoke_vi'. We keep them in a set once we emit an
206 // Emscripten EH symbol so we don't emit the same symbol twice.
207 if (InvokeDetected && !InvokeSymbols.insert(Sym).second)
208 continue;
209
210 Sym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
211 if (!Sym->getSignature()) {
212 Sym->setSignature(Signature.get());
213 addSignature(std::move(Signature));
214 } else {
215 // This symbol has already been created and had a signature. Discard it.
216 Signature.reset();
217 }
218
219 getTargetStreamer()->emitFunctionType(Sym);
220
221 if (F.hasFnAttribute("wasm-import-module")) {
222 StringRef Name =
223 F.getFnAttribute("wasm-import-module").getValueAsString();
224 Sym->setImportModule(storeName(Name));
225 getTargetStreamer()->emitImportModule(Sym, Name);
226 }
227 if (F.hasFnAttribute("wasm-import-name")) {
228 // If this is a converted Emscripten EH/SjLj symbol, we shouldn't use
229 // the original function name but the converted symbol name.
230 StringRef Name =
231 InvokeDetected
232 ? Sym->getName()
233 : F.getFnAttribute("wasm-import-name").getValueAsString();
234 Sym->setImportName(storeName(Name));
235 getTargetStreamer()->emitImportName(Sym, Name);
236 }
237 }
238
239 if (F.hasFnAttribute("wasm-export-name")) {
240 auto *Sym = cast<MCSymbolWasm>(getSymbol(&F));
241 StringRef Name = F.getFnAttribute("wasm-export-name").getValueAsString();
242 Sym->setExportName(storeName(Name));
243 getTargetStreamer()->emitExportName(Sym, Name);
244 }
245 }
246
247 for (const auto &G : M.globals()) {
248 if (!G.hasInitializer() && G.hasExternalLinkage()) {
249 if (G.getValueType()->isSized()) {
250 uint16_t Size = M.getDataLayout().getTypeAllocSize(G.getValueType());
251 OutStreamer->emitELFSize(getSymbol(&G),
252 MCConstantExpr::create(Size, OutContext));
253 }
254 }
255 }
256
257 if (const NamedMDNode *Named = M.getNamedMetadata("wasm.custom_sections")) {
258 for (const Metadata *MD : Named->operands()) {
259 const auto *Tuple = dyn_cast<MDTuple>(MD);
260 if (!Tuple || Tuple->getNumOperands() != 2)
261 continue;
262 const MDString *Name = dyn_cast<MDString>(Tuple->getOperand(0));
263 const MDString *Contents = dyn_cast<MDString>(Tuple->getOperand(1));
264 if (!Name || !Contents)
265 continue;
266
267 OutStreamer->PushSection();
268 std::string SectionName = (".custom_section." + Name->getString()).str();
269 MCSectionWasm *MySection =
270 OutContext.getWasmSection(SectionName, SectionKind::getMetadata());
271 OutStreamer->SwitchSection(MySection);
272 OutStreamer->emitBytes(Contents->getString());
273 OutStreamer->PopSection();
274 }
275 }
276
277 EmitProducerInfo(M);
278 EmitTargetFeatures(M);
279 }
280
EmitProducerInfo(Module & M)281 void WebAssemblyAsmPrinter::EmitProducerInfo(Module &M) {
282 llvm::SmallVector<std::pair<std::string, std::string>, 4> Languages;
283 if (const NamedMDNode *Debug = M.getNamedMetadata("llvm.dbg.cu")) {
284 llvm::SmallSet<StringRef, 4> SeenLanguages;
285 for (size_t I = 0, E = Debug->getNumOperands(); I < E; ++I) {
286 const auto *CU = cast<DICompileUnit>(Debug->getOperand(I));
287 StringRef Language = dwarf::LanguageString(CU->getSourceLanguage());
288 Language.consume_front("DW_LANG_");
289 if (SeenLanguages.insert(Language).second)
290 Languages.emplace_back(Language.str(), "");
291 }
292 }
293
294 llvm::SmallVector<std::pair<std::string, std::string>, 4> Tools;
295 if (const NamedMDNode *Ident = M.getNamedMetadata("llvm.ident")) {
296 llvm::SmallSet<StringRef, 4> SeenTools;
297 for (size_t I = 0, E = Ident->getNumOperands(); I < E; ++I) {
298 const auto *S = cast<MDString>(Ident->getOperand(I)->getOperand(0));
299 std::pair<StringRef, StringRef> Field = S->getString().split("version");
300 StringRef Name = Field.first.trim();
301 StringRef Version = Field.second.trim();
302 if (SeenTools.insert(Name).second)
303 Tools.emplace_back(Name.str(), Version.str());
304 }
305 }
306
307 int FieldCount = int(!Languages.empty()) + int(!Tools.empty());
308 if (FieldCount != 0) {
309 MCSectionWasm *Producers = OutContext.getWasmSection(
310 ".custom_section.producers", SectionKind::getMetadata());
311 OutStreamer->PushSection();
312 OutStreamer->SwitchSection(Producers);
313 OutStreamer->emitULEB128IntValue(FieldCount);
314 for (auto &Producers : {std::make_pair("language", &Languages),
315 std::make_pair("processed-by", &Tools)}) {
316 if (Producers.second->empty())
317 continue;
318 OutStreamer->emitULEB128IntValue(strlen(Producers.first));
319 OutStreamer->emitBytes(Producers.first);
320 OutStreamer->emitULEB128IntValue(Producers.second->size());
321 for (auto &Producer : *Producers.second) {
322 OutStreamer->emitULEB128IntValue(Producer.first.size());
323 OutStreamer->emitBytes(Producer.first);
324 OutStreamer->emitULEB128IntValue(Producer.second.size());
325 OutStreamer->emitBytes(Producer.second);
326 }
327 }
328 OutStreamer->PopSection();
329 }
330 }
331
EmitTargetFeatures(Module & M)332 void WebAssemblyAsmPrinter::EmitTargetFeatures(Module &M) {
333 struct FeatureEntry {
334 uint8_t Prefix;
335 std::string Name;
336 };
337
338 // Read target features and linkage policies from module metadata
339 SmallVector<FeatureEntry, 4> EmittedFeatures;
340 auto EmitFeature = [&](std::string Feature) {
341 std::string MDKey = (StringRef("wasm-feature-") + Feature).str();
342 Metadata *Policy = M.getModuleFlag(MDKey);
343 if (Policy == nullptr)
344 return;
345
346 FeatureEntry Entry;
347 Entry.Prefix = 0;
348 Entry.Name = Feature;
349
350 if (auto *MD = cast<ConstantAsMetadata>(Policy))
351 if (auto *I = cast<ConstantInt>(MD->getValue()))
352 Entry.Prefix = I->getZExtValue();
353
354 // Silently ignore invalid metadata
355 if (Entry.Prefix != wasm::WASM_FEATURE_PREFIX_USED &&
356 Entry.Prefix != wasm::WASM_FEATURE_PREFIX_REQUIRED &&
357 Entry.Prefix != wasm::WASM_FEATURE_PREFIX_DISALLOWED)
358 return;
359
360 EmittedFeatures.push_back(Entry);
361 };
362
363 for (const SubtargetFeatureKV &KV : WebAssemblyFeatureKV) {
364 EmitFeature(KV.Key);
365 }
366 // This pseudo-feature tells the linker whether shared memory would be safe
367 EmitFeature("shared-mem");
368
369 if (EmittedFeatures.size() == 0)
370 return;
371
372 // Emit features and linkage policies into the "target_features" section
373 MCSectionWasm *FeaturesSection = OutContext.getWasmSection(
374 ".custom_section.target_features", SectionKind::getMetadata());
375 OutStreamer->PushSection();
376 OutStreamer->SwitchSection(FeaturesSection);
377
378 OutStreamer->emitULEB128IntValue(EmittedFeatures.size());
379 for (auto &F : EmittedFeatures) {
380 OutStreamer->emitIntValue(F.Prefix, 1);
381 OutStreamer->emitULEB128IntValue(F.Name.size());
382 OutStreamer->emitBytes(F.Name);
383 }
384
385 OutStreamer->PopSection();
386 }
387
emitConstantPool()388 void WebAssemblyAsmPrinter::emitConstantPool() {
389 assert(MF->getConstantPool()->getConstants().empty() &&
390 "WebAssembly disables constant pools");
391 }
392
emitJumpTableInfo()393 void WebAssemblyAsmPrinter::emitJumpTableInfo() {
394 // Nothing to do; jump tables are incorporated into the instruction stream.
395 }
396
emitFunctionBodyStart()397 void WebAssemblyAsmPrinter::emitFunctionBodyStart() {
398 const Function &F = MF->getFunction();
399 SmallVector<MVT, 1> ResultVTs;
400 SmallVector<MVT, 4> ParamVTs;
401 computeSignatureVTs(F.getFunctionType(), &F, F, TM, ParamVTs, ResultVTs);
402
403 auto Signature = signatureFromMVTs(ResultVTs, ParamVTs);
404 auto *WasmSym = cast<MCSymbolWasm>(CurrentFnSym);
405 WasmSym->setSignature(Signature.get());
406 addSignature(std::move(Signature));
407 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
408
409 getTargetStreamer()->emitFunctionType(WasmSym);
410
411 // Emit the function index.
412 if (MDNode *Idx = F.getMetadata("wasm.index")) {
413 assert(Idx->getNumOperands() == 1);
414
415 getTargetStreamer()->emitIndIdx(AsmPrinter::lowerConstant(
416 cast<ConstantAsMetadata>(Idx->getOperand(0))->getValue()));
417 }
418
419 SmallVector<wasm::ValType, 16> Locals;
420 valTypesFromMVTs(MFI->getLocals(), Locals);
421 getTargetStreamer()->emitLocal(Locals);
422
423 AsmPrinter::emitFunctionBodyStart();
424 }
425
emitInstruction(const MachineInstr * MI)426 void WebAssemblyAsmPrinter::emitInstruction(const MachineInstr *MI) {
427 LLVM_DEBUG(dbgs() << "EmitInstruction: " << *MI << '\n');
428
429 switch (MI->getOpcode()) {
430 case WebAssembly::ARGUMENT_i32:
431 case WebAssembly::ARGUMENT_i32_S:
432 case WebAssembly::ARGUMENT_i64:
433 case WebAssembly::ARGUMENT_i64_S:
434 case WebAssembly::ARGUMENT_f32:
435 case WebAssembly::ARGUMENT_f32_S:
436 case WebAssembly::ARGUMENT_f64:
437 case WebAssembly::ARGUMENT_f64_S:
438 case WebAssembly::ARGUMENT_v16i8:
439 case WebAssembly::ARGUMENT_v16i8_S:
440 case WebAssembly::ARGUMENT_v8i16:
441 case WebAssembly::ARGUMENT_v8i16_S:
442 case WebAssembly::ARGUMENT_v4i32:
443 case WebAssembly::ARGUMENT_v4i32_S:
444 case WebAssembly::ARGUMENT_v2i64:
445 case WebAssembly::ARGUMENT_v2i64_S:
446 case WebAssembly::ARGUMENT_v4f32:
447 case WebAssembly::ARGUMENT_v4f32_S:
448 case WebAssembly::ARGUMENT_v2f64:
449 case WebAssembly::ARGUMENT_v2f64_S:
450 // These represent values which are live into the function entry, so there's
451 // no instruction to emit.
452 break;
453 case WebAssembly::FALLTHROUGH_RETURN: {
454 // These instructions represent the implicit return at the end of a
455 // function body.
456 if (isVerbose()) {
457 OutStreamer->AddComment("fallthrough-return");
458 OutStreamer->AddBlankLine();
459 }
460 break;
461 }
462 case WebAssembly::COMPILER_FENCE:
463 // This is a compiler barrier that prevents instruction reordering during
464 // backend compilation, and should not be emitted.
465 break;
466 case WebAssembly::EXTRACT_EXCEPTION_I32:
467 case WebAssembly::EXTRACT_EXCEPTION_I32_S:
468 // These are pseudo instructions that simulates popping values from stack.
469 // We print these only when we have -wasm-keep-registers on for assembly
470 // readability.
471 if (!WasmKeepRegisters)
472 break;
473 LLVM_FALLTHROUGH;
474 default: {
475 WebAssemblyMCInstLower MCInstLowering(OutContext, *this);
476 MCInst TmpInst;
477 MCInstLowering.lower(MI, TmpInst);
478 EmitToStreamer(*OutStreamer, TmpInst);
479 break;
480 }
481 }
482 }
483
PrintAsmOperand(const MachineInstr * MI,unsigned OpNo,const char * ExtraCode,raw_ostream & OS)484 bool WebAssemblyAsmPrinter::PrintAsmOperand(const MachineInstr *MI,
485 unsigned OpNo,
486 const char *ExtraCode,
487 raw_ostream &OS) {
488 // First try the generic code, which knows about modifiers like 'c' and 'n'.
489 if (!AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, OS))
490 return false;
491
492 if (!ExtraCode) {
493 const MachineOperand &MO = MI->getOperand(OpNo);
494 switch (MO.getType()) {
495 case MachineOperand::MO_Immediate:
496 OS << MO.getImm();
497 return false;
498 case MachineOperand::MO_Register:
499 // FIXME: only opcode that still contains registers, as required by
500 // MachineInstr::getDebugVariable().
501 assert(MI->getOpcode() == WebAssembly::INLINEASM);
502 OS << regToString(MO);
503 return false;
504 case MachineOperand::MO_GlobalAddress:
505 PrintSymbolOperand(MO, OS);
506 return false;
507 case MachineOperand::MO_ExternalSymbol:
508 GetExternalSymbolSymbol(MO.getSymbolName())->print(OS, MAI);
509 printOffset(MO.getOffset(), OS);
510 return false;
511 case MachineOperand::MO_MachineBasicBlock:
512 MO.getMBB()->getSymbol()->print(OS, MAI);
513 return false;
514 default:
515 break;
516 }
517 }
518
519 return true;
520 }
521
PrintAsmMemoryOperand(const MachineInstr * MI,unsigned OpNo,const char * ExtraCode,raw_ostream & OS)522 bool WebAssemblyAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
523 unsigned OpNo,
524 const char *ExtraCode,
525 raw_ostream &OS) {
526 // The current approach to inline asm is that "r" constraints are expressed
527 // as local indices, rather than values on the operand stack. This simplifies
528 // using "r" as it eliminates the need to push and pop the values in a
529 // particular order, however it also makes it impossible to have an "m"
530 // constraint. So we don't support it.
531
532 return AsmPrinter::PrintAsmMemoryOperand(MI, OpNo, ExtraCode, OS);
533 }
534
535 // Force static initialization.
LLVMInitializeWebAssemblyAsmPrinter()536 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeWebAssemblyAsmPrinter() {
537 RegisterAsmPrinter<WebAssemblyAsmPrinter> X(getTheWebAssemblyTarget32());
538 RegisterAsmPrinter<WebAssemblyAsmPrinter> Y(getTheWebAssemblyTarget64());
539 }
540