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