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/AsmPrinterAnalysis.h"
37#include "llvm/CodeGen/MachineConstantPool.h"
38#include "llvm/CodeGen/MachineFunction.h"
39#include "llvm/CodeGen/MachineFunctionAnalysisManager.h"
40#include "llvm/CodeGen/MachineInstr.h"
41#include "llvm/CodeGen/MachineModuleInfoImpls.h"
42#include "llvm/CodeGen/MachinePassManager.h"
43#include "llvm/IR/Analysis.h"
44#include "llvm/IR/DataLayout.h"
45#include "llvm/IR/DebugInfoMetadata.h"
46#include "llvm/IR/GlobalVariable.h"
47#include "llvm/IR/Metadata.h"
48#include "llvm/IR/Module.h"
49#include "llvm/IR/PassManager.h"
50#include "llvm/MC/MCContext.h"
51#include "llvm/MC/MCSectionWasm.h"
52#include "llvm/MC/MCStreamer.h"
53#include "llvm/MC/MCSymbol.h"
54#include "llvm/MC/MCSymbolWasm.h"
55#include "llvm/MC/TargetRegistry.h"
56#include "llvm/Support/Compiler.h"
57#include "llvm/Support/Debug.h"
58#include "llvm/Support/raw_ostream.h"
59
60using namespace llvm;
61
62#define DEBUG_TYPE "asm-printer"
63
64extern cl::opt<bool> WasmKeepRegisters;
65
66//===----------------------------------------------------------------------===//
67// Helpers.
68//===----------------------------------------------------------------------===//
69
70MVT WebAssemblyAsmPrinter::getRegType(unsigned RegNo) const {
71 const TargetRegisterInfo *TRI = Subtarget->getRegisterInfo();
72 const TargetRegisterClass *TRC = MRI->getRegClass(Reg: RegNo);
73 for (MVT T : {MVT::i32, MVT::i64, MVT::f32, MVT::f64, MVT::v16i8, MVT::v8i16,
74 MVT::v4i32, MVT::v2i64, MVT::v4f32, MVT::v2f64, MVT::v8f16})
75 if (TRI->isTypeLegalForClass(RC: *TRC, T))
76 return T;
77 LLVM_DEBUG(errs() << "Unknown type for register number: " << RegNo);
78 llvm_unreachable("Unknown register type");
79 return MVT::Other;
80}
81
82std::string WebAssemblyAsmPrinter::regToString(const MachineOperand &MO) {
83 Register RegNo = MO.getReg();
84 assert(RegNo.isVirtual() &&
85 "Unlowered physical register encountered during assembly printing");
86 assert(!MFI->isVRegStackified(RegNo));
87 unsigned WAReg = MFI->getWAReg(VReg: RegNo);
88 assert(WAReg != WebAssembly::UnusedReg);
89 return '$' + utostr(X: WAReg);
90}
91
92WebAssemblyTargetStreamer *WebAssemblyAsmPrinter::getTargetStreamer() {
93 MCTargetStreamer *TS = OutStreamer->getTargetStreamer();
94 return static_cast<WebAssemblyTargetStreamer *>(TS);
95}
96
97// Emscripten exception handling helpers
98//
99// This converts invoke names generated by LowerEmscriptenEHSjLj to real names
100// that are expected by JavaScript glue code. The invoke names generated by
101// Emscripten JS glue code are based on their argument and return types; for
102// example, for a function that takes an i32 and returns nothing, it is
103// 'invoke_vi'. But the format of invoke generated by LowerEmscriptenEHSjLj pass
104// contains a mangled string generated from their IR types, for example,
105// "__invoke_void_%struct.mystruct*_int", because final wasm types are not
106// available in the IR pass. So we convert those names to the form that
107// Emscripten JS code expects.
108//
109// Refer to LowerEmscriptenEHSjLj pass for more details.
110
111// Returns true if the given function name is an invoke name generated by
112// LowerEmscriptenEHSjLj pass.
113static bool isEmscriptenInvokeName(StringRef Name) {
114 if (Name.front() == '"' && Name.back() == '"')
115 Name = Name.substr(Start: 1, N: Name.size() - 2);
116 return Name.starts_with(Prefix: "__invoke_");
117}
118
119// Returns a character that represents the given wasm value type in invoke
120// signatures.
121static char getInvokeSig(wasm::ValType VT) {
122 switch (VT) {
123 case wasm::ValType::I32:
124 return 'i';
125 case wasm::ValType::I64:
126 return 'j';
127 case wasm::ValType::F32:
128 return 'f';
129 case wasm::ValType::F64:
130 return 'd';
131 case wasm::ValType::V128:
132 return 'V';
133 case wasm::ValType::FUNCREF:
134 return 'F';
135 case wasm::ValType::EXTERNREF:
136 return 'X';
137 case wasm::ValType::EXNREF:
138 return 'E';
139 default:
140 llvm_unreachable("Unhandled wasm::ValType enum");
141 }
142}
143
144// Given the wasm signature, generate the invoke name in the format JS glue code
145// expects.
146static std::string getEmscriptenInvokeSymbolName(wasm::WasmSignature *Sig) {
147 assert(Sig->Returns.size() <= 1);
148 std::string Ret = "invoke_";
149 if (!Sig->Returns.empty())
150 for (auto VT : Sig->Returns)
151 Ret += getInvokeSig(VT);
152 else
153 Ret += 'v';
154 // Invokes' first argument is a pointer to the original function, so skip it
155 for (unsigned I = 1, E = Sig->Params.size(); I < E; I++)
156 Ret += getInvokeSig(VT: Sig->Params[I]);
157 return Ret;
158}
159
160//===----------------------------------------------------------------------===//
161// WebAssemblyAsmPrinter Implementation.
162//===----------------------------------------------------------------------===//
163
164MCSymbolWasm *WebAssemblyAsmPrinter::getMCSymbolForFunction(
165 const Function *F, wasm::WasmSignature *Sig, bool &InvokeDetected) {
166 MCSymbolWasm *WasmSym = nullptr;
167
168 const bool EnableEmEH =
169 WebAssembly::WasmEnableEmEH || WebAssembly::WasmEnableEmSjLj;
170 if (EnableEmEH && isEmscriptenInvokeName(Name: F->getName())) {
171 assert(Sig);
172 InvokeDetected = true;
173 if (Sig->Returns.size() > 1) {
174 std::string Msg =
175 "Emscripten EH/SjLj does not support multivalue returns: " +
176 std::string(F->getName()) + ": " +
177 WebAssembly::signatureToString(Sig);
178 report_fatal_error(reason: Twine(Msg));
179 }
180 WasmSym = static_cast<MCSymbolWasm *>(
181 GetExternalSymbolSymbol(Sym: getEmscriptenInvokeSymbolName(Sig)));
182 } else {
183 WasmSym = static_cast<MCSymbolWasm *>(getSymbol(GV: F));
184 }
185 return WasmSym;
186}
187
188void WebAssemblyAsmPrinter::emitGlobalVariable(const GlobalVariable *GV) {
189 if (!WebAssembly::isWasmVarAddressSpace(AS: GV->getAddressSpace())) {
190 AsmPrinter::emitGlobalVariable(GV);
191 return;
192 }
193
194 assert(!GV->isThreadLocal());
195 auto *Sym = static_cast<MCSymbolWasm *>(getSymbol(GV));
196 if (!Sym->getType()) {
197 SmallVector<MVT, 1> VTs;
198 Type *GlobalVT = GV->getValueType();
199 // Function-specific subtargets are not needed here: WebAssembly
200 // coalesces features before isel, so use the TargetMachine's
201 // module-wide subtarget to compute legal value types.
202 auto &WasmTM = static_cast<const WebAssemblyTargetMachine &>(TM);
203 const WebAssemblySubtarget *ST = WasmTM.getSubtargetImpl();
204 const WebAssemblyTargetLowering &TLI = *ST->getTargetLowering();
205 computeLegalValueVTs(TLI, Ctx&: GV->getParent()->getContext(),
206 DL: GV->getDataLayout(), Ty: GlobalVT, ValueVTs&: VTs);
207
208 WebAssembly::wasmSymbolSetType(Sym, GlobalVT, VTs,
209 /*Mutable=*/!GV->isConstant());
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 = Name == "__stack_pointer" || Name == "__tls_base";
240 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_GLOBAL);
241 WasmSym->setGlobalType(wasm::WasmGlobalType{
242 .Type: uint8_t(Subtarget.hasAddr64() ? wasm::WASM_TYPE_I64
243 : wasm::WASM_TYPE_I32),
244 .Mutable: Mutable});
245 return WasmSym;
246 }
247
248 if (Name.starts_with(Prefix: "GCC_except_table")) {
249 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_DATA);
250 return WasmSym;
251 }
252
253 SmallVector<wasm::ValType, 4> Returns;
254 SmallVector<wasm::ValType, 4> Params;
255 if (Name == "__cpp_exception" || Name == "__c_longjmp") {
256 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_TAG);
257 WasmSym->setExternal(true);
258
259 // Currently both C++ exceptions and C longjmps have a single pointer type
260 // param. For C++ exceptions it is a pointer to an exception object, and for
261 // C longjmps it is pointer to a struct that contains a setjmp buffer and a
262 // longjmp return value. We may consider using multiple value parameters for
263 // longjmps later when multivalue support is ready.
264 wasm::ValType AddrType =
265 Subtarget.hasAddr64() ? wasm::ValType::I64 : wasm::ValType::I32;
266 Params.push_back(Elt: AddrType);
267 } else if (Name == "__wasm_get_stack_pointer" ||
268 Name == "__wasm_get_tls_base") {
269 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
270 Returns.push_back(Elt: wasm::ValType::I32);
271 } else if (Name == "__wasm_set_stack_pointer" ||
272 Name == "__wasm_set_tls_base") {
273 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
274 Params.push_back(Elt: wasm::ValType::I32);
275 } else { // Function symbols
276 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
277 WebAssembly::getLibcallSignature(Subtarget, Name, Rets&: Returns, Params);
278 }
279 auto Signature = OutContext.createWasmSignature();
280 Signature->Returns = std::move(Returns);
281 Signature->Params = std::move(Params);
282 WasmSym->setSignature(Signature);
283
284 return WasmSym;
285}
286
287void WebAssemblyAsmPrinter::emitSymbolType(const MCSymbolWasm *Sym) {
288 std::optional<wasm::WasmSymbolType> WasmTy = Sym->getType();
289 if (!WasmTy)
290 return;
291
292 switch (*WasmTy) {
293 case wasm::WASM_SYMBOL_TYPE_GLOBAL:
294 getTargetStreamer()->emitGlobalType(Sym);
295 break;
296 case wasm::WASM_SYMBOL_TYPE_TAG:
297 getTargetStreamer()->emitTagType(Sym);
298 break;
299 case wasm::WASM_SYMBOL_TYPE_TABLE:
300 getTargetStreamer()->emitTableType(Sym);
301 break;
302 default:
303 break; // We only handle globals, tags and tables here
304 }
305}
306
307void WebAssemblyAsmPrinter::emitDecls(const Module &M) {
308 if (signaturesEmitted)
309 return;
310 signaturesEmitted = true;
311
312 // Normally symbols for globals get discovered as the MI gets lowered,
313 // but we need to know about them ahead of time. This will however,
314 // only find symbols that have been used. Unused symbols from globals will
315 // not be found here.
316 MachineModuleInfoWasm &MMIW = MMI->getObjFileInfo<MachineModuleInfoWasm>();
317 for (StringRef Name : MMIW.MachineSymbolsUsed) {
318 auto *WasmSym = static_cast<MCSymbolWasm *>(getOrCreateWasmSymbol(Name));
319 if (WasmSym->isFunction()) {
320 // TODO(wvo): is there any case where this overlaps with the call to
321 // emitFunctionType in the loop below?
322 getTargetStreamer()->emitFunctionType(Sym: WasmSym);
323 }
324 }
325
326 for (auto &It : OutContext.getSymbols()) {
327 // Emit .globaltype, .tagtype, or .tabletype declarations for extern
328 // declarations, i.e. those that have only been declared (but not defined)
329 // in the current module
330 auto Sym = static_cast<MCSymbolWasm *>(It.getValue().Symbol);
331 if (Sym && !Sym->isDefined())
332 emitSymbolType(Sym);
333 }
334
335 // We handle `__funcref_call_table` specially here.
336 //
337 // Unlike most table symbols, which are attached to a `GlobalVariable`
338 // this one is a directly created, freestanding MCSymbol, much like
339 // `__indirect_function_table`. However, given that the table is always
340 // identical (single element, default initialized), we declare it
341 // weak in each object, and define it here rather than in the linker.
342 //
343 // TODO: consider moving this definition elsewhere, or doing away with
344 // the table entirely (in favor of `call_ref` exclusively).
345 {
346 StringRef Name = "__funcref_call_table";
347 auto *Sym = static_cast<MCSymbolWasm *>(OutContext.lookupSymbol(Name));
348 if (Sym) {
349 if (!Sym->isFunctionTable())
350 OutContext.reportError(L: SMLoc(), Msg: "symbol is not a wasm funcref table");
351
352 // symbol is declared weak in `getOrCreateFuncrefCallTableSymbol`
353 assert(Sym->isWeak());
354 OutStreamer->emitSymbolAttribute(Symbol: Sym, Attribute: MCSA_Weak);
355
356 // Make sure we haven't already emitted it for whatever reason.
357 assert(!Sym->isDefined());
358
359 // Actually define the symbol.
360 // Confusingly enough, `emitLabel` is what "defines" a MCSymbol.
361 // Provides it a fragment, so that it `!isUndefined`
362 OutStreamer->emitLabel(Symbol: Sym);
363 // No initializer needed. Default ref.null is good
364 OutStreamer->addBlankLine();
365 }
366 }
367
368 DenseSet<MCSymbol *> InvokeSymbols;
369 for (const auto &F : M) {
370 if (F.isIntrinsic())
371 continue;
372
373 // Emit function type info for all functions. This will emit duplicate
374 // information for defined functions (which already have function type
375 // info emitted alongside their definition), but this is necessary in
376 // order to enable the single-pass WebAssemblyAsmTypeCheck to succeed.
377 SmallVector<MVT, 4> Results;
378 SmallVector<MVT, 4> Params;
379 computeSignatureVTs(Ty: F.getFunctionType(), TargetFunc: &F, ContextFunc: F, TM, Params, Results);
380 // At this point these MCSymbols may or may not have been created already
381 // and thus also contain a signature, but we need to get the signature
382 // anyway here in case it is an invoke that has not yet been created. We
383 // will discard it later if it turns out not to be necessary.
384 auto Signature = signatureFromMVTs(Ctx&: OutContext, Results, Params);
385 bool InvokeDetected = false;
386 auto *Sym = getMCSymbolForFunction(F: &F, Sig: Signature, InvokeDetected);
387
388 // Multiple functions can be mapped to the same invoke symbol. For
389 // example, two IR functions '__invoke_void_i8*' and '__invoke_void_i32'
390 // are both mapped to '__invoke_vi'. We keep them in a set once we emit an
391 // Emscripten EH symbol so we don't emit the same symbol twice.
392 if (InvokeDetected && !InvokeSymbols.insert(V: Sym).second)
393 continue;
394
395 Sym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
396 if (!Sym->getSignature()) {
397 Sym->setSignature(Signature);
398 }
399
400 getTargetStreamer()->emitFunctionType(Sym);
401
402 if (F.hasFnAttribute(Kind: "wasm-import-module")) {
403 StringRef Name =
404 F.getFnAttribute(Kind: "wasm-import-module").getValueAsString();
405 Sym->setImportModule(OutContext.allocateString(s: Name));
406 getTargetStreamer()->emitImportModule(Sym, ImportModule: Name);
407 }
408 if (F.hasFnAttribute(Kind: "wasm-import-name")) {
409 // If this is a converted Emscripten EH/SjLj symbol, we shouldn't use
410 // the original function name but the converted symbol name.
411 StringRef Name =
412 InvokeDetected
413 ? Sym->getName()
414 : F.getFnAttribute(Kind: "wasm-import-name").getValueAsString();
415 Sym->setImportName(OutContext.allocateString(s: Name));
416 getTargetStreamer()->emitImportName(Sym, ImportName: Name);
417 }
418
419 if (F.hasFnAttribute(Kind: "wasm-export-name")) {
420 auto *Sym = static_cast<MCSymbolWasm *>(getSymbol(GV: &F));
421 StringRef Name = F.getFnAttribute(Kind: "wasm-export-name").getValueAsString();
422 Sym->setExportName(OutContext.allocateString(s: Name));
423 getTargetStreamer()->emitExportName(Sym, ExportName: Name);
424 }
425 }
426}
427
428void WebAssemblyAsmPrinter::emitEndOfAsmFile(Module &M) {
429 // This is required to emit external declarations (like .functypes) when
430 // no functions are defined in the compilation unit and therefore,
431 // emitDecls() is not called until now.
432 emitDecls(M);
433
434 // When a function's address is taken, a TABLE_INDEX relocation is emitted
435 // against the function symbol at the use site. However the relocation
436 // doesn't explicitly refer to the table. In the future we may want to
437 // define a new kind of reloc against both the function and the table, so
438 // that the linker can see that the function symbol keeps the table alive,
439 // but for now manually mark the table as live.
440 for (const auto &F : M) {
441 if (!F.isIntrinsic() && F.hasAddressTaken()) {
442 MCSymbolWasm *FunctionTable =
443 WebAssembly::getOrCreateFunctionTableSymbol(Ctx&: OutContext, Subtarget);
444 OutStreamer->emitSymbolAttribute(Symbol: FunctionTable, Attribute: MCSA_NoDeadStrip);
445 break;
446 }
447 }
448
449 for (const auto &G : M.globals()) {
450 if (!G.hasInitializer() && G.hasExternalLinkage() &&
451 !WebAssembly::isWasmVarAddressSpace(AS: G.getAddressSpace()) &&
452 G.getValueType()->isSized()) {
453 uint16_t Size = G.getGlobalSize(DL: M.getDataLayout());
454 OutStreamer->emitELFSize(Symbol: getSymbol(GV: &G),
455 Value: MCConstantExpr::create(Value: Size, Ctx&: OutContext));
456 }
457 }
458
459 if (const NamedMDNode *Named = M.getNamedMetadata(Name: "wasm.custom_sections")) {
460 for (const Metadata *MD : Named->operands()) {
461 const auto *Tuple = dyn_cast<MDTuple>(Val: MD);
462 if (!Tuple || Tuple->getNumOperands() != 2)
463 continue;
464 const MDString *Name = dyn_cast<MDString>(Val: Tuple->getOperand(I: 0));
465 const MDString *Contents = dyn_cast<MDString>(Val: Tuple->getOperand(I: 1));
466 if (!Name || !Contents)
467 continue;
468
469 OutStreamer->pushSection();
470 std::string SectionName = (".custom_section." + Name->getString()).str();
471 MCSectionWasm *MySection =
472 OutContext.getWasmSection(Section: SectionName, K: SectionKind::getMetadata());
473 OutStreamer->switchSection(Section: MySection);
474 OutStreamer->emitBytes(Data: Contents->getString());
475 OutStreamer->popSection();
476 }
477 }
478
479 EmitProducerInfo(M);
480 EmitTargetFeatures(M);
481 EmitFunctionAttributes(M);
482}
483
484void WebAssemblyAsmPrinter::EmitProducerInfo(Module &M) {
485 llvm::SmallVector<std::pair<std::string, std::string>, 4> Languages;
486 if (const NamedMDNode *Debug = M.getNamedMetadata(Name: "llvm.dbg.cu")) {
487 llvm::SmallSet<StringRef, 4> SeenLanguages;
488 for (size_t I = 0, E = Debug->getNumOperands(); I < E; ++I) {
489 const auto *CU = cast<DICompileUnit>(Val: Debug->getOperand(i: I));
490 StringRef Language =
491 dwarf::LanguageString(Language: CU->getSourceLanguage().getUnversionedName());
492
493 Language.consume_front(Prefix: "DW_LANG_");
494 if (SeenLanguages.insert(V: Language).second)
495 Languages.emplace_back(Args: Language.str(), Args: "");
496 }
497 }
498
499 llvm::SmallVector<std::pair<std::string, std::string>, 4> Tools;
500 if (const NamedMDNode *Ident = M.getNamedMetadata(Name: "llvm.ident")) {
501 llvm::SmallSet<StringRef, 4> SeenTools;
502 for (size_t I = 0, E = Ident->getNumOperands(); I < E; ++I) {
503 const auto *S = cast<MDString>(Val: Ident->getOperand(i: I)->getOperand(I: 0));
504 std::pair<StringRef, StringRef> Field = S->getString().split(Separator: "version");
505 StringRef Name = Field.first.trim();
506 StringRef Version = Field.second.trim();
507 if (SeenTools.insert(V: Name).second)
508 Tools.emplace_back(Args: Name.str(), Args: Version.str());
509 }
510 }
511
512 int FieldCount = int(!Languages.empty()) + int(!Tools.empty());
513 if (FieldCount != 0) {
514 MCSectionWasm *Producers = OutContext.getWasmSection(
515 Section: ".custom_section.producers", K: SectionKind::getMetadata());
516 OutStreamer->pushSection();
517 OutStreamer->switchSection(Section: Producers);
518 OutStreamer->emitULEB128IntValue(Value: FieldCount);
519 for (auto &Producers : {std::make_pair(x: "language", y: &Languages),
520 std::make_pair(x: "processed-by", y: &Tools)}) {
521 if (Producers.second->empty())
522 continue;
523 OutStreamer->emitULEB128IntValue(Value: strlen(s: Producers.first));
524 OutStreamer->emitBytes(Data: Producers.first);
525 OutStreamer->emitULEB128IntValue(Value: Producers.second->size());
526 for (auto &Producer : *Producers.second) {
527 OutStreamer->emitULEB128IntValue(Value: Producer.first.size());
528 OutStreamer->emitBytes(Data: Producer.first);
529 OutStreamer->emitULEB128IntValue(Value: Producer.second.size());
530 OutStreamer->emitBytes(Data: Producer.second);
531 }
532 }
533 OutStreamer->popSection();
534 }
535}
536
537void WebAssemblyAsmPrinter::EmitTargetFeatures(Module &M) {
538 struct FeatureEntry {
539 uint8_t Prefix;
540 std::string Name;
541 };
542
543 // Read target features and linkage policies from module metadata
544 SmallVector<FeatureEntry, 4> EmittedFeatures;
545 auto EmitFeature = [&](std::string Feature) {
546 std::string MDKey = (StringRef("wasm-feature-") + Feature).str();
547 Metadata *Policy = M.getModuleFlag(Key: MDKey);
548 if (Policy == nullptr)
549 return;
550
551 FeatureEntry Entry;
552 Entry.Prefix = 0;
553 Entry.Name = Feature;
554
555 if (auto *MD = cast<ConstantAsMetadata>(Val: Policy))
556 if (auto *I = cast<ConstantInt>(Val: MD->getValue()))
557 Entry.Prefix = I->getZExtValue();
558
559 // Silently ignore invalid metadata
560 if (Entry.Prefix != wasm::WASM_FEATURE_PREFIX_USED &&
561 Entry.Prefix != wasm::WASM_FEATURE_PREFIX_DISALLOWED)
562 return;
563
564 EmittedFeatures.push_back(Elt: Entry);
565 };
566
567 // If we never compiled a single function, Subtarget is null.
568 if (!Subtarget) {
569 Subtarget = static_cast<WebAssemblyTargetMachine &>(TM).getSubtargetImpl(
570 CPU: std::string(TM.getTargetCPU()),
571 FS: std::string(TM.getTargetFeatureString()));
572 }
573 for (const SubtargetFeatureKV &KV : Subtarget->getAllProcessorFeatures()) {
574 EmitFeature(KV.key());
575 }
576 // This pseudo-feature tells the linker whether shared memory would be safe
577 EmitFeature("shared-mem");
578
579 // This is an "architecture", not a "feature", but we emit it as such for
580 // the benefit of tools like Binaryen and consistency with other producers.
581 if (Subtarget->hasAddr64()) {
582 // Can't use EmitFeature since "wasm-feature-memory64" is not a module
583 // flag.
584 EmittedFeatures.push_back(Elt: {.Prefix: wasm::WASM_FEATURE_PREFIX_USED, .Name: "memory64"});
585 }
586
587 if (EmittedFeatures.size() == 0)
588 return;
589
590 // Emit features and linkage policies into the "target_features" section
591 MCSectionWasm *FeaturesSection = OutContext.getWasmSection(
592 Section: ".custom_section.target_features", K: SectionKind::getMetadata());
593 OutStreamer->pushSection();
594 OutStreamer->switchSection(Section: FeaturesSection);
595
596 OutStreamer->emitULEB128IntValue(Value: EmittedFeatures.size());
597 for (auto &F : EmittedFeatures) {
598 OutStreamer->emitIntValue(Value: F.Prefix, Size: 1);
599 OutStreamer->emitULEB128IntValue(Value: F.Name.size());
600 OutStreamer->emitBytes(Data: F.Name);
601 }
602
603 OutStreamer->popSection();
604}
605
606void WebAssemblyAsmPrinter::EmitFunctionAttributes(Module &M) {
607 auto V = M.getNamedGlobal(Name: "llvm.global.annotations");
608 if (!V)
609 return;
610
611 // Group all the custom attributes by name.
612 MapVector<StringRef, SmallVector<MCSymbol *, 4>> CustomSections;
613 const ConstantArray *CA = cast<ConstantArray>(Val: V->getOperand(i_nocapture: 0));
614 for (Value *Op : CA->operands()) {
615 auto *CS = cast<ConstantStruct>(Val: Op);
616 // The first field is a pointer to the annotated variable.
617 Value *AnnotatedVar = CS->getOperand(i_nocapture: 0)->stripPointerCasts();
618 // Only annotated functions are supported for now.
619 if (!isa<Function>(Val: AnnotatedVar))
620 continue;
621 auto *F = cast<Function>(Val: AnnotatedVar);
622
623 // The second field is a pointer to a global annotation string.
624 auto *GV = cast<GlobalVariable>(Val: CS->getOperand(i_nocapture: 1)->stripPointerCasts());
625 StringRef AnnotationString;
626 getConstantStringInfo(V: GV, Str&: AnnotationString);
627 auto *Sym = static_cast<MCSymbolWasm *>(getSymbol(GV: F));
628 CustomSections[AnnotationString].push_back(Elt: Sym);
629 }
630
631 // Emit a custom section for each unique attribute.
632 for (const auto &[Name, Symbols] : CustomSections) {
633 MCSectionWasm *CustomSection = OutContext.getWasmSection(
634 Section: ".custom_section.llvm.func_attr.annotate." + Name, K: SectionKind::getMetadata());
635 OutStreamer->pushSection();
636 OutStreamer->switchSection(Section: CustomSection);
637
638 for (auto &Sym : Symbols) {
639 OutStreamer->emitValue(
640 Value: MCSymbolRefExpr::create(Symbol: Sym, specifier: WebAssembly::S_FUNCINDEX, Ctx&: OutContext),
641 Size: 4);
642 }
643 OutStreamer->popSection();
644 }
645}
646
647void WebAssemblyAsmPrinter::emitConstantPool() {
648 emitDecls(M: *MMI->getModule());
649 assert(MF->getConstantPool()->getConstants().empty() &&
650 "WebAssembly disables constant pools");
651}
652
653void WebAssemblyAsmPrinter::emitJumpTableInfo() {
654 // Nothing to do; jump tables are incorporated into the instruction stream.
655}
656
657void WebAssemblyAsmPrinter::emitFunctionBodyStart() {
658 const Function &F = MF->getFunction();
659 SmallVector<MVT, 1> ResultVTs;
660 SmallVector<MVT, 4> ParamVTs;
661 computeSignatureVTs(Ty: F.getFunctionType(), TargetFunc: &F, ContextFunc: F, TM, Params&: ParamVTs, Results&: ResultVTs);
662
663 auto Signature = signatureFromMVTs(Ctx&: OutContext, Results: ResultVTs, Params: ParamVTs);
664 auto *WasmSym = static_cast<MCSymbolWasm *>(CurrentFnSym);
665 WasmSym->setSignature(Signature);
666 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
667
668 getTargetStreamer()->emitFunctionType(Sym: WasmSym);
669
670 // Emit the function index.
671 if (MDNode *Idx = F.getMetadata(Kind: "wasm.index")) {
672 assert(Idx->getNumOperands() == 1);
673
674 getTargetStreamer()->emitIndIdx(Value: AsmPrinter::lowerConstant(
675 CV: cast<ConstantAsMetadata>(Val: Idx->getOperand(I: 0))->getValue()));
676 }
677
678 SmallVector<wasm::ValType, 16> Locals;
679 valTypesFromMVTs(In: MFI->getLocals(), Out&: Locals);
680 getTargetStreamer()->emitLocal(Types: Locals);
681
682 AsmPrinter::emitFunctionBodyStart();
683}
684
685void WebAssemblyAsmPrinter::emitInstruction(const MachineInstr *MI) {
686 LLVM_DEBUG(dbgs() << "EmitInstruction: " << *MI << '\n');
687 WebAssembly_MC::verifyInstructionPredicates(Opcode: MI->getOpcode(),
688 Features: Subtarget->getFeatureBits());
689
690 switch (MI->getOpcode()) {
691 case WebAssembly::ARGUMENT_i32:
692 case WebAssembly::ARGUMENT_i32_S:
693 case WebAssembly::ARGUMENT_i64:
694 case WebAssembly::ARGUMENT_i64_S:
695 case WebAssembly::ARGUMENT_f32:
696 case WebAssembly::ARGUMENT_f32_S:
697 case WebAssembly::ARGUMENT_f64:
698 case WebAssembly::ARGUMENT_f64_S:
699 case WebAssembly::ARGUMENT_v16i8:
700 case WebAssembly::ARGUMENT_v16i8_S:
701 case WebAssembly::ARGUMENT_v8i16:
702 case WebAssembly::ARGUMENT_v8i16_S:
703 case WebAssembly::ARGUMENT_v4i32:
704 case WebAssembly::ARGUMENT_v4i32_S:
705 case WebAssembly::ARGUMENT_v2i64:
706 case WebAssembly::ARGUMENT_v2i64_S:
707 case WebAssembly::ARGUMENT_v4f32:
708 case WebAssembly::ARGUMENT_v4f32_S:
709 case WebAssembly::ARGUMENT_v2f64:
710 case WebAssembly::ARGUMENT_v2f64_S:
711 case WebAssembly::ARGUMENT_v8f16:
712 case WebAssembly::ARGUMENT_v8f16_S:
713 case WebAssembly::ARGUMENT_externref:
714 case WebAssembly::ARGUMENT_externref_S:
715 case WebAssembly::ARGUMENT_funcref:
716 case WebAssembly::ARGUMENT_funcref_S:
717 case WebAssembly::ARGUMENT_exnref:
718 case WebAssembly::ARGUMENT_exnref_S:
719 // These represent values which are live into the function entry, so there's
720 // no instruction to emit.
721 break;
722 case WebAssembly::FALLTHROUGH_RETURN: {
723 // These instructions represent the implicit return at the end of a
724 // function body.
725 if (isVerbose()) {
726 OutStreamer->AddComment(T: "fallthrough-return");
727 OutStreamer->addBlankLine();
728 }
729 break;
730 }
731 case WebAssembly::COMPILER_FENCE:
732 // This is a compiler barrier that prevents instruction reordering during
733 // backend compilation, and should not be emitted.
734 break;
735 case WebAssembly::CATCH:
736 case WebAssembly::CATCH_S:
737 case WebAssembly::CATCH_REF:
738 case WebAssembly::CATCH_REF_S:
739 case WebAssembly::CATCH_ALL:
740 case WebAssembly::CATCH_ALL_S:
741 case WebAssembly::CATCH_ALL_REF:
742 case WebAssembly::CATCH_ALL_REF_S:
743 // These are pseudo instructions to represent catch clauses in try_table
744 // instruction to simulate block return values.
745 break;
746 default: {
747 WebAssemblyMCInstLower MCInstLowering(OutContext, *this);
748 MCInst TmpInst;
749 MCInstLowering.lower(MI, OutMI&: TmpInst);
750 EmitToStreamer(S&: *OutStreamer, Inst: TmpInst);
751 break;
752 }
753 }
754}
755
756bool WebAssemblyAsmPrinter::PrintAsmOperand(const MachineInstr *MI,
757 unsigned OpNo,
758 const char *ExtraCode,
759 raw_ostream &OS) {
760 // First try the generic code, which knows about modifiers like 'c' and 'n'.
761 if (!AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, OS))
762 return false;
763
764 if (!ExtraCode) {
765 const MachineOperand &MO = MI->getOperand(i: OpNo);
766 switch (MO.getType()) {
767 case MachineOperand::MO_Immediate:
768 OS << MO.getImm();
769 return false;
770 case MachineOperand::MO_Register:
771 // FIXME: only opcode that still contains registers, as required by
772 // MachineInstr::getDebugVariable().
773 assert(MI->getOpcode() == WebAssembly::INLINEASM);
774 OS << regToString(MO);
775 return false;
776 case MachineOperand::MO_GlobalAddress:
777 PrintSymbolOperand(MO, OS);
778 return false;
779 case MachineOperand::MO_ExternalSymbol:
780 GetExternalSymbolSymbol(Sym: MO.getSymbolName())->print(OS, MAI);
781 printOffset(Offset: MO.getOffset(), OS);
782 return false;
783 case MachineOperand::MO_MachineBasicBlock:
784 MO.getMBB()->getSymbol()->print(OS, MAI);
785 return false;
786 default:
787 break;
788 }
789 }
790
791 return true;
792}
793
794bool WebAssemblyAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
795 unsigned OpNo,
796 const char *ExtraCode,
797 raw_ostream &OS) {
798 // The current approach to inline asm is that "r" constraints are expressed
799 // as local indices, rather than values on the operand stack. This simplifies
800 // using "r" as it eliminates the need to push and pop the values in a
801 // particular order, however it also makes it impossible to have an "m"
802 // constraint. So we don't support it.
803
804 return AsmPrinter::PrintAsmMemoryOperand(MI, OpNo, ExtraCode, OS);
805}
806
807char WebAssemblyAsmPrinter::ID = 0;
808
809INITIALIZE_PASS(WebAssemblyAsmPrinter, "webassembly-asm-printer",
810 "WebAssembly Assembly Printer", false, false)
811
812// Force static initialization.
813extern "C" LLVM_ABI LLVM_EXTERNAL_VISIBILITY void
814LLVMInitializeWebAssemblyAsmPrinter() {
815 RegisterAsmPrinter<WebAssemblyAsmPrinter> X(getTheWebAssemblyTarget32());
816 RegisterAsmPrinter<WebAssemblyAsmPrinter> Y(getTheWebAssemblyTarget64());
817}
818
819PreservedAnalyses
820WebAssemblyAsmPrinterBeginPass::run(Module &M, ModuleAnalysisManager &MAM) {
821 WebAssemblyAsmPrinter &AsmPrinter = static_cast<WebAssemblyAsmPrinter &>(
822 MAM.getResult<AsmPrinterAnalysis>(IR&: M).getPrinter());
823 setupModuleAsmPrinter(M, MAM, AsmPrinter);
824 AsmPrinter.doInitialization(M);
825 return PreservedAnalyses::all();
826}
827
828PreservedAnalyses
829WebAssemblyAsmPrinterPass::run(MachineFunction &MF,
830 MachineFunctionAnalysisManager &MFAM) {
831 WebAssemblyAsmPrinter &AsmPrinter = static_cast<WebAssemblyAsmPrinter &>(
832 MFAM.getResult<ModuleAnalysisManagerMachineFunctionProxy>(IR&: MF)
833 .getCachedResult<AsmPrinterAnalysis>(IR&: *MF.getFunction().getParent())
834 ->getPrinter());
835 setupMachineFunctionAsmPrinter(MFAM, MF, AsmPrinter);
836 AsmPrinter.runOnMachineFunction(MF);
837 return PreservedAnalyses::all();
838}
839
840PreservedAnalyses
841WebAssemblyAsmPrinterEndPass::run(Module &M, ModuleAnalysisManager &MAM) {
842 WebAssemblyAsmPrinter &AsmPrinter = static_cast<WebAssemblyAsmPrinter &>(
843 MAM.getResult<AsmPrinterAnalysis>(IR&: M).getPrinter());
844 setupModuleAsmPrinter(M, MAM, AsmPrinter);
845 AsmPrinter.doFinalization(M);
846 return PreservedAnalyses::all();
847}
848