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/WebAssemblyMCAsmInfo.h"
18#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
19#include "MCTargetDesc/WebAssemblyTargetStreamer.h"
20#include "TargetInfo/WebAssemblyTargetInfo.h"
21#include "Utils/WebAssemblyTypeUtilities.h"
22#include "WebAssembly.h"
23#include "WebAssemblyMCInstLower.h"
24#include "WebAssemblyMachineFunctionInfo.h"
25#include "WebAssemblyRegisterInfo.h"
26#include "WebAssemblyRuntimeLibcallSignatures.h"
27#include "WebAssemblyTargetMachine.h"
28#include "WebAssemblyUtilities.h"
29#include "llvm/ADT/MapVector.h"
30#include "llvm/ADT/SmallSet.h"
31#include "llvm/ADT/StringExtras.h"
32#include "llvm/Analysis/ValueTracking.h"
33#include "llvm/BinaryFormat/Wasm.h"
34#include "llvm/CodeGen/Analysis.h"
35#include "llvm/CodeGen/AsmPrinter.h"
36#include "llvm/CodeGen/MachineConstantPool.h"
37#include "llvm/CodeGen/MachineInstr.h"
38#include "llvm/CodeGen/MachineModuleInfoImpls.h"
39#include "llvm/IR/DataLayout.h"
40#include "llvm/IR/DebugInfoMetadata.h"
41#include "llvm/IR/GlobalVariable.h"
42#include "llvm/IR/Metadata.h"
43#include "llvm/IR/Module.h"
44#include "llvm/MC/MCContext.h"
45#include "llvm/MC/MCSectionWasm.h"
46#include "llvm/MC/MCStreamer.h"
47#include "llvm/MC/MCSymbol.h"
48#include "llvm/MC/MCSymbolWasm.h"
49#include "llvm/MC/TargetRegistry.h"
50#include "llvm/Support/Compiler.h"
51#include "llvm/Support/Debug.h"
52#include "llvm/Support/raw_ostream.h"
53
54using namespace llvm;
55
56#define DEBUG_TYPE "asm-printer"
57
58extern cl::opt<bool> WasmKeepRegisters;
59
60//===----------------------------------------------------------------------===//
61// Helpers.
62//===----------------------------------------------------------------------===//
63
64MVT WebAssemblyAsmPrinter::getRegType(unsigned RegNo) const {
65 const TargetRegisterInfo *TRI = Subtarget->getRegisterInfo();
66 const TargetRegisterClass *TRC = MRI->getRegClass(Reg: RegNo);
67 for (MVT T : {MVT::i32, MVT::i64, MVT::f32, MVT::f64, MVT::v16i8, MVT::v8i16,
68 MVT::v4i32, MVT::v2i64, MVT::v4f32, MVT::v2f64, MVT::v8f16})
69 if (TRI->isTypeLegalForClass(RC: *TRC, T))
70 return T;
71 LLVM_DEBUG(errs() << "Unknown type for register number: " << RegNo);
72 llvm_unreachable("Unknown register type");
73 return MVT::Other;
74}
75
76std::string WebAssemblyAsmPrinter::regToString(const MachineOperand &MO) {
77 Register RegNo = MO.getReg();
78 assert(RegNo.isVirtual() &&
79 "Unlowered physical register encountered during assembly printing");
80 assert(!MFI->isVRegStackified(RegNo));
81 unsigned WAReg = MFI->getWAReg(VReg: RegNo);
82 assert(WAReg != WebAssembly::UnusedReg);
83 return '$' + utostr(X: WAReg);
84}
85
86WebAssemblyTargetStreamer *WebAssemblyAsmPrinter::getTargetStreamer() {
87 MCTargetStreamer *TS = OutStreamer->getTargetStreamer();
88 return static_cast<WebAssemblyTargetStreamer *>(TS);
89}
90
91// Emscripten exception handling helpers
92//
93// This converts invoke names generated by LowerEmscriptenEHSjLj to real names
94// that are expected by JavaScript glue code. The invoke names generated by
95// Emscripten JS glue code are based on their argument and return types; for
96// example, for a function that takes an i32 and returns nothing, it is
97// 'invoke_vi'. But the format of invoke generated by LowerEmscriptenEHSjLj pass
98// contains a mangled string generated from their IR types, for example,
99// "__invoke_void_%struct.mystruct*_int", because final wasm types are not
100// available in the IR pass. So we convert those names to the form that
101// Emscripten JS code expects.
102//
103// Refer to LowerEmscriptenEHSjLj pass for more details.
104
105// Returns true if the given function name is an invoke name generated by
106// LowerEmscriptenEHSjLj pass.
107static bool isEmscriptenInvokeName(StringRef Name) {
108 if (Name.front() == '"' && Name.back() == '"')
109 Name = Name.substr(Start: 1, N: Name.size() - 2);
110 return Name.starts_with(Prefix: "__invoke_");
111}
112
113// Returns a character that represents the given wasm value type in invoke
114// signatures.
115static char getInvokeSig(wasm::ValType VT) {
116 switch (VT) {
117 case wasm::ValType::I32:
118 return 'i';
119 case wasm::ValType::I64:
120 return 'j';
121 case wasm::ValType::F32:
122 return 'f';
123 case wasm::ValType::F64:
124 return 'd';
125 case wasm::ValType::V128:
126 return 'V';
127 case wasm::ValType::FUNCREF:
128 return 'F';
129 case wasm::ValType::EXTERNREF:
130 return 'X';
131 case wasm::ValType::EXNREF:
132 return 'E';
133 default:
134 llvm_unreachable("Unhandled wasm::ValType enum");
135 }
136}
137
138// Given the wasm signature, generate the invoke name in the format JS glue code
139// expects.
140static std::string getEmscriptenInvokeSymbolName(wasm::WasmSignature *Sig) {
141 assert(Sig->Returns.size() <= 1);
142 std::string Ret = "invoke_";
143 if (!Sig->Returns.empty())
144 for (auto VT : Sig->Returns)
145 Ret += getInvokeSig(VT);
146 else
147 Ret += 'v';
148 // Invokes' first argument is a pointer to the original function, so skip it
149 for (unsigned I = 1, E = Sig->Params.size(); I < E; I++)
150 Ret += getInvokeSig(VT: Sig->Params[I]);
151 return Ret;
152}
153
154//===----------------------------------------------------------------------===//
155// WebAssemblyAsmPrinter Implementation.
156//===----------------------------------------------------------------------===//
157
158MCSymbolWasm *WebAssemblyAsmPrinter::getMCSymbolForFunction(
159 const Function *F, wasm::WasmSignature *Sig, bool &InvokeDetected) {
160 MCSymbolWasm *WasmSym = nullptr;
161
162 const bool EnableEmEH =
163 WebAssembly::WasmEnableEmEH || WebAssembly::WasmEnableEmSjLj;
164 if (EnableEmEH && isEmscriptenInvokeName(Name: F->getName())) {
165 assert(Sig);
166 InvokeDetected = true;
167 if (Sig->Returns.size() > 1) {
168 std::string Msg =
169 "Emscripten EH/SjLj does not support multivalue returns: " +
170 std::string(F->getName()) + ": " +
171 WebAssembly::signatureToString(Sig);
172 report_fatal_error(reason: Twine(Msg));
173 }
174 WasmSym = static_cast<MCSymbolWasm *>(
175 GetExternalSymbolSymbol(Sym: getEmscriptenInvokeSymbolName(Sig)));
176 } else {
177 WasmSym = static_cast<MCSymbolWasm *>(getSymbol(GV: F));
178 }
179 return WasmSym;
180}
181
182void WebAssemblyAsmPrinter::emitGlobalVariable(const GlobalVariable *GV) {
183 if (GV->hasCommonLinkage()) {
184 OutContext.reportError(L: SMLoc(),
185 Msg: "common symbols are not yet implemented for Wasm: " +
186 getSymbol(GV)->getName());
187 return;
188 }
189
190 if (!WebAssembly::isWasmVarAddressSpace(AS: GV->getAddressSpace())) {
191 AsmPrinter::emitGlobalVariable(GV);
192 return;
193 }
194
195 assert(!GV->isThreadLocal());
196 auto *Sym = static_cast<MCSymbolWasm *>(getSymbol(GV));
197 if (!Sym->getType()) {
198 SmallVector<MVT, 1> VTs;
199 Type *GlobalVT = GV->getValueType();
200 // Function-specific subtargets are not needed here: WebAssembly
201 // coalesces features before isel, so use the TargetMachine's
202 // module-wide subtarget to compute legal value types.
203 auto &WasmTM = static_cast<const WebAssemblyTargetMachine &>(TM);
204 const WebAssemblySubtarget *ST = WasmTM.getSubtargetImpl();
205 const WebAssemblyTargetLowering &TLI = *ST->getTargetLowering();
206 computeLegalValueVTs(TLI, Ctx&: GV->getParent()->getContext(),
207 DL: GV->getDataLayout(), Ty: GlobalVT, ValueVTs&: VTs);
208
209 WebAssembly::wasmSymbolSetType(Sym, GlobalVT, VTs);
210 }
211
212 emitVisibility(Sym, Visibility: GV->getVisibility(), IsDefinition: !GV->isDeclaration());
213 emitSymbolType(Sym);
214 if (GV->hasInitializer()) {
215 assert(getSymbolPreferLocal(*GV) == Sym);
216 emitLinkage(GV, GVSym: Sym);
217 OutStreamer->emitLabel(Symbol: Sym);
218 // TODO: Actually emit the initializer value. Otherwise the global has the
219 // default value for its type (0, ref.null, etc).
220 OutStreamer->addBlankLine();
221 }
222}
223
224MCSymbol *WebAssemblyAsmPrinter::getOrCreateWasmSymbol(StringRef Name) {
225 auto *WasmSym = static_cast<MCSymbolWasm *>(GetExternalSymbolSymbol(Sym: Name));
226 // May be called multiple times, so early out.
227 if (WasmSym->getType())
228 return WasmSym;
229
230 const WebAssemblySubtarget &Subtarget = getSubtarget();
231
232 // Except for certain known symbols, all symbols used by CodeGen are
233 // functions. It's OK to hardcode knowledge of specific symbols here; this
234 // method is precisely there for fetching the signatures of known
235 // Clang-provided symbols.
236 if (Name == "__stack_pointer" || Name == "__tls_base" ||
237 Name == "__memory_base" || Name == "__table_base" ||
238 Name == "__tls_size" || Name == "__tls_align") {
239 bool Mutable =
240 Name == "__stack_pointer" || Name == "__tls_base";
241 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_GLOBAL);
242 WasmSym->setGlobalType(wasm::WasmGlobalType{
243 .Type: uint8_t(Subtarget.hasAddr64() ? wasm::WASM_TYPE_I64
244 : wasm::WASM_TYPE_I32),
245 .Mutable: Mutable});
246 return WasmSym;
247 }
248
249 if (Name.starts_with(Prefix: "GCC_except_table")) {
250 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_DATA);
251 return WasmSym;
252 }
253
254 SmallVector<wasm::ValType, 4> Returns;
255 SmallVector<wasm::ValType, 4> Params;
256 if (Name == "__cpp_exception" || Name == "__c_longjmp") {
257 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_TAG);
258 WasmSym->setExternal(true);
259
260 // Currently both C++ exceptions and C longjmps have a single pointer type
261 // param. For C++ exceptions it is a pointer to an exception object, and for
262 // C longjmps it is pointer to a struct that contains a setjmp buffer and a
263 // longjmp return value. We may consider using multiple value parameters for
264 // longjmps later when multivalue support is ready.
265 wasm::ValType AddrType =
266 Subtarget.hasAddr64() ? wasm::ValType::I64 : wasm::ValType::I32;
267 Params.push_back(Elt: AddrType);
268 } else { // Function symbols
269 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
270 WebAssembly::getLibcallSignature(Subtarget, Name, Rets&: Returns, Params);
271 }
272 auto Signature = OutContext.createWasmSignature();
273 Signature->Returns = std::move(Returns);
274 Signature->Params = std::move(Params);
275 WasmSym->setSignature(Signature);
276
277 return WasmSym;
278}
279
280void WebAssemblyAsmPrinter::emitSymbolType(const MCSymbolWasm *Sym) {
281 std::optional<wasm::WasmSymbolType> WasmTy = Sym->getType();
282 if (!WasmTy)
283 return;
284
285 switch (*WasmTy) {
286 case wasm::WASM_SYMBOL_TYPE_GLOBAL:
287 getTargetStreamer()->emitGlobalType(Sym);
288 break;
289 case wasm::WASM_SYMBOL_TYPE_TAG:
290 getTargetStreamer()->emitTagType(Sym);
291 break;
292 case wasm::WASM_SYMBOL_TYPE_TABLE:
293 getTargetStreamer()->emitTableType(Sym);
294 break;
295 default:
296 break; // We only handle globals, tags and tables here
297 }
298}
299
300void WebAssemblyAsmPrinter::emitDecls(const Module &M) {
301 if (signaturesEmitted)
302 return;
303 signaturesEmitted = true;
304
305 // Normally symbols for globals get discovered as the MI gets lowered,
306 // but we need to know about them ahead of time. This will however,
307 // only find symbols that have been used. Unused symbols from globals will
308 // not be found here.
309 MachineModuleInfoWasm &MMIW = MMI->getObjFileInfo<MachineModuleInfoWasm>();
310 for (StringRef Name : MMIW.MachineSymbolsUsed) {
311 auto *WasmSym = static_cast<MCSymbolWasm *>(getOrCreateWasmSymbol(Name));
312 if (WasmSym->isFunction()) {
313 // TODO(wvo): is there any case where this overlaps with the call to
314 // emitFunctionType in the loop below?
315 getTargetStreamer()->emitFunctionType(Sym: WasmSym);
316 }
317 }
318
319 for (auto &It : OutContext.getSymbols()) {
320 // Emit .globaltype, .tagtype, or .tabletype declarations for extern
321 // declarations, i.e. those that have only been declared (but not defined)
322 // in the current module
323 auto Sym = static_cast<MCSymbolWasm *>(It.getValue().Symbol);
324 if (Sym && !Sym->isDefined())
325 emitSymbolType(Sym);
326 }
327
328 DenseSet<MCSymbol *> InvokeSymbols;
329 for (const auto &F : M) {
330 if (F.isIntrinsic())
331 continue;
332
333 // Emit function type info for all functions. This will emit duplicate
334 // information for defined functions (which already have function type
335 // info emitted alongside their definition), but this is necessary in
336 // order to enable the single-pass WebAssemblyAsmTypeCheck to succeed.
337 SmallVector<MVT, 4> Results;
338 SmallVector<MVT, 4> Params;
339 computeSignatureVTs(Ty: F.getFunctionType(), TargetFunc: &F, ContextFunc: F, TM, Params, Results);
340 // At this point these MCSymbols may or may not have been created already
341 // and thus also contain a signature, but we need to get the signature
342 // anyway here in case it is an invoke that has not yet been created. We
343 // will discard it later if it turns out not to be necessary.
344 auto Signature = signatureFromMVTs(Ctx&: OutContext, Results, Params);
345 bool InvokeDetected = false;
346 auto *Sym = getMCSymbolForFunction(F: &F, Sig: Signature, InvokeDetected);
347
348 // Multiple functions can be mapped to the same invoke symbol. For
349 // example, two IR functions '__invoke_void_i8*' and '__invoke_void_i32'
350 // are both mapped to '__invoke_vi'. We keep them in a set once we emit an
351 // Emscripten EH symbol so we don't emit the same symbol twice.
352 if (InvokeDetected && !InvokeSymbols.insert(V: Sym).second)
353 continue;
354
355 Sym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
356 if (!Sym->getSignature()) {
357 Sym->setSignature(Signature);
358 }
359
360 getTargetStreamer()->emitFunctionType(Sym);
361
362 if (F.hasFnAttribute(Kind: "wasm-import-module")) {
363 StringRef Name =
364 F.getFnAttribute(Kind: "wasm-import-module").getValueAsString();
365 Sym->setImportModule(OutContext.allocateString(s: Name));
366 getTargetStreamer()->emitImportModule(Sym, ImportModule: Name);
367 }
368 if (F.hasFnAttribute(Kind: "wasm-import-name")) {
369 // If this is a converted Emscripten EH/SjLj symbol, we shouldn't use
370 // the original function name but the converted symbol name.
371 StringRef Name =
372 InvokeDetected
373 ? Sym->getName()
374 : F.getFnAttribute(Kind: "wasm-import-name").getValueAsString();
375 Sym->setImportName(OutContext.allocateString(s: Name));
376 getTargetStreamer()->emitImportName(Sym, ImportName: Name);
377 }
378
379 if (F.hasFnAttribute(Kind: "wasm-export-name")) {
380 auto *Sym = static_cast<MCSymbolWasm *>(getSymbol(GV: &F));
381 StringRef Name = F.getFnAttribute(Kind: "wasm-export-name").getValueAsString();
382 Sym->setExportName(OutContext.allocateString(s: Name));
383 getTargetStreamer()->emitExportName(Sym, ExportName: Name);
384 }
385 }
386}
387
388void WebAssemblyAsmPrinter::emitEndOfAsmFile(Module &M) {
389 // This is required to emit external declarations (like .functypes) when
390 // no functions are defined in the compilation unit and therefore,
391 // emitDecls() is not called until now.
392 emitDecls(M);
393
394 // When a function's address is taken, a TABLE_INDEX relocation is emitted
395 // against the function symbol at the use site. However the relocation
396 // doesn't explicitly refer to the table. In the future we may want to
397 // define a new kind of reloc against both the function and the table, so
398 // that the linker can see that the function symbol keeps the table alive,
399 // but for now manually mark the table as live.
400 for (const auto &F : M) {
401 if (!F.isIntrinsic() && F.hasAddressTaken()) {
402 MCSymbolWasm *FunctionTable =
403 WebAssembly::getOrCreateFunctionTableSymbol(Ctx&: OutContext, Subtarget);
404 OutStreamer->emitSymbolAttribute(Symbol: FunctionTable, Attribute: MCSA_NoDeadStrip);
405 break;
406 }
407 }
408
409 for (const auto &G : M.globals()) {
410 if (!G.hasInitializer() && G.hasExternalLinkage() &&
411 !WebAssembly::isWasmVarAddressSpace(AS: G.getAddressSpace()) &&
412 G.getValueType()->isSized()) {
413 uint16_t Size = G.getGlobalSize(DL: M.getDataLayout());
414 OutStreamer->emitELFSize(Symbol: getSymbol(GV: &G),
415 Value: MCConstantExpr::create(Value: Size, Ctx&: OutContext));
416 }
417 }
418
419 if (const NamedMDNode *Named = M.getNamedMetadata(Name: "wasm.custom_sections")) {
420 for (const Metadata *MD : Named->operands()) {
421 const auto *Tuple = dyn_cast<MDTuple>(Val: MD);
422 if (!Tuple || Tuple->getNumOperands() != 2)
423 continue;
424 const MDString *Name = dyn_cast<MDString>(Val: Tuple->getOperand(I: 0));
425 const MDString *Contents = dyn_cast<MDString>(Val: Tuple->getOperand(I: 1));
426 if (!Name || !Contents)
427 continue;
428
429 OutStreamer->pushSection();
430 std::string SectionName = (".custom_section." + Name->getString()).str();
431 MCSectionWasm *MySection =
432 OutContext.getWasmSection(Section: SectionName, K: SectionKind::getMetadata());
433 OutStreamer->switchSection(Section: MySection);
434 OutStreamer->emitBytes(Data: Contents->getString());
435 OutStreamer->popSection();
436 }
437 }
438
439 EmitProducerInfo(M);
440 EmitTargetFeatures(M);
441 EmitFunctionAttributes(M);
442}
443
444void WebAssemblyAsmPrinter::EmitProducerInfo(Module &M) {
445 llvm::SmallVector<std::pair<std::string, std::string>, 4> Languages;
446 if (const NamedMDNode *Debug = M.getNamedMetadata(Name: "llvm.dbg.cu")) {
447 llvm::SmallSet<StringRef, 4> SeenLanguages;
448 for (size_t I = 0, E = Debug->getNumOperands(); I < E; ++I) {
449 const auto *CU = cast<DICompileUnit>(Val: Debug->getOperand(i: I));
450 StringRef Language =
451 dwarf::LanguageString(Language: CU->getSourceLanguage().getUnversionedName());
452
453 Language.consume_front(Prefix: "DW_LANG_");
454 if (SeenLanguages.insert(V: Language).second)
455 Languages.emplace_back(Args: Language.str(), Args: "");
456 }
457 }
458
459 llvm::SmallVector<std::pair<std::string, std::string>, 4> Tools;
460 if (const NamedMDNode *Ident = M.getNamedMetadata(Name: "llvm.ident")) {
461 llvm::SmallSet<StringRef, 4> SeenTools;
462 for (size_t I = 0, E = Ident->getNumOperands(); I < E; ++I) {
463 const auto *S = cast<MDString>(Val: Ident->getOperand(i: I)->getOperand(I: 0));
464 std::pair<StringRef, StringRef> Field = S->getString().split(Separator: "version");
465 StringRef Name = Field.first.trim();
466 StringRef Version = Field.second.trim();
467 if (SeenTools.insert(V: Name).second)
468 Tools.emplace_back(Args: Name.str(), Args: Version.str());
469 }
470 }
471
472 int FieldCount = int(!Languages.empty()) + int(!Tools.empty());
473 if (FieldCount != 0) {
474 MCSectionWasm *Producers = OutContext.getWasmSection(
475 Section: ".custom_section.producers", K: SectionKind::getMetadata());
476 OutStreamer->pushSection();
477 OutStreamer->switchSection(Section: Producers);
478 OutStreamer->emitULEB128IntValue(Value: FieldCount);
479 for (auto &Producers : {std::make_pair(x: "language", y: &Languages),
480 std::make_pair(x: "processed-by", y: &Tools)}) {
481 if (Producers.second->empty())
482 continue;
483 OutStreamer->emitULEB128IntValue(Value: strlen(s: Producers.first));
484 OutStreamer->emitBytes(Data: Producers.first);
485 OutStreamer->emitULEB128IntValue(Value: Producers.second->size());
486 for (auto &Producer : *Producers.second) {
487 OutStreamer->emitULEB128IntValue(Value: Producer.first.size());
488 OutStreamer->emitBytes(Data: Producer.first);
489 OutStreamer->emitULEB128IntValue(Value: Producer.second.size());
490 OutStreamer->emitBytes(Data: Producer.second);
491 }
492 }
493 OutStreamer->popSection();
494 }
495}
496
497void WebAssemblyAsmPrinter::EmitTargetFeatures(Module &M) {
498 struct FeatureEntry {
499 uint8_t Prefix;
500 std::string Name;
501 };
502
503 // Read target features and linkage policies from module metadata
504 SmallVector<FeatureEntry, 4> EmittedFeatures;
505 auto EmitFeature = [&](std::string Feature) {
506 std::string MDKey = (StringRef("wasm-feature-") + Feature).str();
507 Metadata *Policy = M.getModuleFlag(Key: MDKey);
508 if (Policy == nullptr)
509 return;
510
511 FeatureEntry Entry;
512 Entry.Prefix = 0;
513 Entry.Name = Feature;
514
515 if (auto *MD = cast<ConstantAsMetadata>(Val: Policy))
516 if (auto *I = cast<ConstantInt>(Val: MD->getValue()))
517 Entry.Prefix = I->getZExtValue();
518
519 // Silently ignore invalid metadata
520 if (Entry.Prefix != wasm::WASM_FEATURE_PREFIX_USED &&
521 Entry.Prefix != wasm::WASM_FEATURE_PREFIX_DISALLOWED)
522 return;
523
524 EmittedFeatures.push_back(Elt: Entry);
525 };
526
527 for (const SubtargetFeatureKV &KV : WebAssemblyFeatureKV) {
528 EmitFeature(KV.Key);
529 }
530 // This pseudo-feature tells the linker whether shared memory would be safe
531 EmitFeature("shared-mem");
532
533 // This is an "architecture", not a "feature", but we emit it as such for
534 // the benefit of tools like Binaryen and consistency with other producers.
535 // FIXME: Subtarget is null here, so can't Subtarget->hasAddr64() ?
536 if (M.getDataLayout().getPointerSize() == 8) {
537 // Can't use EmitFeature since "wasm-feature-memory64" is not a module
538 // flag.
539 EmittedFeatures.push_back(Elt: {.Prefix: wasm::WASM_FEATURE_PREFIX_USED, .Name: "memory64"});
540 }
541
542 if (EmittedFeatures.size() == 0)
543 return;
544
545 // Emit features and linkage policies into the "target_features" section
546 MCSectionWasm *FeaturesSection = OutContext.getWasmSection(
547 Section: ".custom_section.target_features", K: SectionKind::getMetadata());
548 OutStreamer->pushSection();
549 OutStreamer->switchSection(Section: FeaturesSection);
550
551 OutStreamer->emitULEB128IntValue(Value: EmittedFeatures.size());
552 for (auto &F : EmittedFeatures) {
553 OutStreamer->emitIntValue(Value: F.Prefix, Size: 1);
554 OutStreamer->emitULEB128IntValue(Value: F.Name.size());
555 OutStreamer->emitBytes(Data: F.Name);
556 }
557
558 OutStreamer->popSection();
559}
560
561void WebAssemblyAsmPrinter::EmitFunctionAttributes(Module &M) {
562 auto V = M.getNamedGlobal(Name: "llvm.global.annotations");
563 if (!V)
564 return;
565
566 // Group all the custom attributes by name.
567 MapVector<StringRef, SmallVector<MCSymbol *, 4>> CustomSections;
568 const ConstantArray *CA = cast<ConstantArray>(Val: V->getOperand(i_nocapture: 0));
569 for (Value *Op : CA->operands()) {
570 auto *CS = cast<ConstantStruct>(Val: Op);
571 // The first field is a pointer to the annotated variable.
572 Value *AnnotatedVar = CS->getOperand(i_nocapture: 0)->stripPointerCasts();
573 // Only annotated functions are supported for now.
574 if (!isa<Function>(Val: AnnotatedVar))
575 continue;
576 auto *F = cast<Function>(Val: AnnotatedVar);
577
578 // The second field is a pointer to a global annotation string.
579 auto *GV = cast<GlobalVariable>(Val: CS->getOperand(i_nocapture: 1)->stripPointerCasts());
580 StringRef AnnotationString;
581 getConstantStringInfo(V: GV, Str&: AnnotationString);
582 auto *Sym = static_cast<MCSymbolWasm *>(getSymbol(GV: F));
583 CustomSections[AnnotationString].push_back(Elt: Sym);
584 }
585
586 // Emit a custom section for each unique attribute.
587 for (const auto &[Name, Symbols] : CustomSections) {
588 MCSectionWasm *CustomSection = OutContext.getWasmSection(
589 Section: ".custom_section.llvm.func_attr.annotate." + Name, K: SectionKind::getMetadata());
590 OutStreamer->pushSection();
591 OutStreamer->switchSection(Section: CustomSection);
592
593 for (auto &Sym : Symbols) {
594 OutStreamer->emitValue(
595 Value: MCSymbolRefExpr::create(Symbol: Sym, specifier: WebAssembly::S_FUNCINDEX, Ctx&: OutContext),
596 Size: 4);
597 }
598 OutStreamer->popSection();
599 }
600}
601
602void WebAssemblyAsmPrinter::emitConstantPool() {
603 emitDecls(M: *MMI->getModule());
604 assert(MF->getConstantPool()->getConstants().empty() &&
605 "WebAssembly disables constant pools");
606}
607
608void WebAssemblyAsmPrinter::emitJumpTableInfo() {
609 // Nothing to do; jump tables are incorporated into the instruction stream.
610}
611
612void WebAssemblyAsmPrinter::emitFunctionBodyStart() {
613 const Function &F = MF->getFunction();
614 SmallVector<MVT, 1> ResultVTs;
615 SmallVector<MVT, 4> ParamVTs;
616 computeSignatureVTs(Ty: F.getFunctionType(), TargetFunc: &F, ContextFunc: F, TM, Params&: ParamVTs, Results&: ResultVTs);
617
618 auto Signature = signatureFromMVTs(Ctx&: OutContext, Results: ResultVTs, Params: ParamVTs);
619 auto *WasmSym = static_cast<MCSymbolWasm *>(CurrentFnSym);
620 WasmSym->setSignature(Signature);
621 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
622
623 getTargetStreamer()->emitFunctionType(Sym: WasmSym);
624
625 // Emit the function index.
626 if (MDNode *Idx = F.getMetadata(Kind: "wasm.index")) {
627 assert(Idx->getNumOperands() == 1);
628
629 getTargetStreamer()->emitIndIdx(Value: AsmPrinter::lowerConstant(
630 CV: cast<ConstantAsMetadata>(Val: Idx->getOperand(I: 0))->getValue()));
631 }
632
633 SmallVector<wasm::ValType, 16> Locals;
634 valTypesFromMVTs(In: MFI->getLocals(), Out&: Locals);
635 getTargetStreamer()->emitLocal(Types: Locals);
636
637 AsmPrinter::emitFunctionBodyStart();
638}
639
640void WebAssemblyAsmPrinter::emitInstruction(const MachineInstr *MI) {
641 LLVM_DEBUG(dbgs() << "EmitInstruction: " << *MI << '\n');
642 WebAssembly_MC::verifyInstructionPredicates(Opcode: MI->getOpcode(),
643 Features: Subtarget->getFeatureBits());
644
645 switch (MI->getOpcode()) {
646 case WebAssembly::ARGUMENT_i32:
647 case WebAssembly::ARGUMENT_i32_S:
648 case WebAssembly::ARGUMENT_i64:
649 case WebAssembly::ARGUMENT_i64_S:
650 case WebAssembly::ARGUMENT_f32:
651 case WebAssembly::ARGUMENT_f32_S:
652 case WebAssembly::ARGUMENT_f64:
653 case WebAssembly::ARGUMENT_f64_S:
654 case WebAssembly::ARGUMENT_v16i8:
655 case WebAssembly::ARGUMENT_v16i8_S:
656 case WebAssembly::ARGUMENT_v8i16:
657 case WebAssembly::ARGUMENT_v8i16_S:
658 case WebAssembly::ARGUMENT_v4i32:
659 case WebAssembly::ARGUMENT_v4i32_S:
660 case WebAssembly::ARGUMENT_v2i64:
661 case WebAssembly::ARGUMENT_v2i64_S:
662 case WebAssembly::ARGUMENT_v4f32:
663 case WebAssembly::ARGUMENT_v4f32_S:
664 case WebAssembly::ARGUMENT_v2f64:
665 case WebAssembly::ARGUMENT_v2f64_S:
666 case WebAssembly::ARGUMENT_v8f16:
667 case WebAssembly::ARGUMENT_v8f16_S:
668 case WebAssembly::ARGUMENT_externref:
669 case WebAssembly::ARGUMENT_externref_S:
670 case WebAssembly::ARGUMENT_funcref:
671 case WebAssembly::ARGUMENT_funcref_S:
672 case WebAssembly::ARGUMENT_exnref:
673 case WebAssembly::ARGUMENT_exnref_S:
674 // These represent values which are live into the function entry, so there's
675 // no instruction to emit.
676 break;
677 case WebAssembly::FALLTHROUGH_RETURN: {
678 // These instructions represent the implicit return at the end of a
679 // function body.
680 if (isVerbose()) {
681 OutStreamer->AddComment(T: "fallthrough-return");
682 OutStreamer->addBlankLine();
683 }
684 break;
685 }
686 case WebAssembly::COMPILER_FENCE:
687 // This is a compiler barrier that prevents instruction reordering during
688 // backend compilation, and should not be emitted.
689 break;
690 case WebAssembly::CATCH:
691 case WebAssembly::CATCH_S:
692 case WebAssembly::CATCH_REF:
693 case WebAssembly::CATCH_REF_S:
694 case WebAssembly::CATCH_ALL:
695 case WebAssembly::CATCH_ALL_S:
696 case WebAssembly::CATCH_ALL_REF:
697 case WebAssembly::CATCH_ALL_REF_S:
698 // These are pseudo instructions to represent catch clauses in try_table
699 // instruction to simulate block return values.
700 break;
701 default: {
702 WebAssemblyMCInstLower MCInstLowering(OutContext, *this);
703 MCInst TmpInst;
704 MCInstLowering.lower(MI, OutMI&: TmpInst);
705 EmitToStreamer(S&: *OutStreamer, Inst: TmpInst);
706 break;
707 }
708 }
709}
710
711bool WebAssemblyAsmPrinter::PrintAsmOperand(const MachineInstr *MI,
712 unsigned OpNo,
713 const char *ExtraCode,
714 raw_ostream &OS) {
715 // First try the generic code, which knows about modifiers like 'c' and 'n'.
716 if (!AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, OS))
717 return false;
718
719 if (!ExtraCode) {
720 const MachineOperand &MO = MI->getOperand(i: OpNo);
721 switch (MO.getType()) {
722 case MachineOperand::MO_Immediate:
723 OS << MO.getImm();
724 return false;
725 case MachineOperand::MO_Register:
726 // FIXME: only opcode that still contains registers, as required by
727 // MachineInstr::getDebugVariable().
728 assert(MI->getOpcode() == WebAssembly::INLINEASM);
729 OS << regToString(MO);
730 return false;
731 case MachineOperand::MO_GlobalAddress:
732 PrintSymbolOperand(MO, OS);
733 return false;
734 case MachineOperand::MO_ExternalSymbol:
735 GetExternalSymbolSymbol(Sym: MO.getSymbolName())->print(OS, MAI);
736 printOffset(Offset: MO.getOffset(), OS);
737 return false;
738 case MachineOperand::MO_MachineBasicBlock:
739 MO.getMBB()->getSymbol()->print(OS, MAI);
740 return false;
741 default:
742 break;
743 }
744 }
745
746 return true;
747}
748
749bool WebAssemblyAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
750 unsigned OpNo,
751 const char *ExtraCode,
752 raw_ostream &OS) {
753 // The current approach to inline asm is that "r" constraints are expressed
754 // as local indices, rather than values on the operand stack. This simplifies
755 // using "r" as it eliminates the need to push and pop the values in a
756 // particular order, however it also makes it impossible to have an "m"
757 // constraint. So we don't support it.
758
759 return AsmPrinter::PrintAsmMemoryOperand(MI, OpNo, ExtraCode, OS);
760}
761
762char WebAssemblyAsmPrinter::ID = 0;
763
764INITIALIZE_PASS(WebAssemblyAsmPrinter, "webassembly-asm-printer",
765 "WebAssembly Assmebly Printer", false, false)
766
767// Force static initialization.
768extern "C" LLVM_ABI LLVM_EXTERNAL_VISIBILITY void
769LLVMInitializeWebAssemblyAsmPrinter() {
770 RegisterAsmPrinter<WebAssemblyAsmPrinter> X(getTheWebAssemblyTarget32());
771 RegisterAsmPrinter<WebAssemblyAsmPrinter> Y(getTheWebAssemblyTarget64());
772}
773