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 (!WebAssembly::isWasmVarAddressSpace(AS: GV->getAddressSpace())) {
184 AsmPrinter::emitGlobalVariable(GV);
185 return;
186 }
187
188 assert(!GV->isThreadLocal());
189 auto *Sym = static_cast<MCSymbolWasm *>(getSymbol(GV));
190 if (!Sym->getType()) {
191 SmallVector<MVT, 1> VTs;
192 Type *GlobalVT = GV->getValueType();
193 if (Subtarget) {
194 // Subtarget is only set when a function is defined, because
195 // each function can declare a different subtarget. For example,
196 // on ARM a compilation unit might have a function on ARM and
197 // another on Thumb. Therefore only if Subtarget is non-null we
198 // can actually calculate the legal VTs.
199 const WebAssemblyTargetLowering &TLI = *Subtarget->getTargetLowering();
200 computeLegalValueVTs(TLI, Ctx&: GV->getParent()->getContext(),
201 DL: GV->getDataLayout(), Ty: GlobalVT, ValueVTs&: VTs);
202 }
203 WebAssembly::wasmSymbolSetType(Sym, GlobalVT, VTs);
204 }
205
206 emitVisibility(Sym, Visibility: GV->getVisibility(), IsDefinition: !GV->isDeclaration());
207 emitSymbolType(Sym);
208 if (GV->hasInitializer()) {
209 assert(getSymbolPreferLocal(*GV) == Sym);
210 emitLinkage(GV, GVSym: Sym);
211 OutStreamer->emitLabel(Symbol: Sym);
212 // TODO: Actually emit the initializer value. Otherwise the global has the
213 // default value for its type (0, ref.null, etc).
214 OutStreamer->addBlankLine();
215 }
216}
217
218MCSymbol *WebAssemblyAsmPrinter::getOrCreateWasmSymbol(StringRef Name) {
219 auto *WasmSym = static_cast<MCSymbolWasm *>(GetExternalSymbolSymbol(Sym: Name));
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 WasmSym->setExternal(true);
253
254 // Currently both C++ exceptions and C longjmps have a single pointer type
255 // param. For C++ exceptions it is a pointer to an exception object, and for
256 // C longjmps it is pointer to a struct that contains a setjmp buffer and a
257 // longjmp return value. We may consider using multiple value parameters for
258 // longjmps later when multivalue support is ready.
259 wasm::ValType AddrType =
260 Subtarget.hasAddr64() ? wasm::ValType::I64 : wasm::ValType::I32;
261 Params.push_back(Elt: AddrType);
262 } else { // Function symbols
263 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
264 WebAssembly::getLibcallSignature(Subtarget, Name, Rets&: Returns, Params);
265 }
266 auto Signature = OutContext.createWasmSignature();
267 Signature->Returns = std::move(Returns);
268 Signature->Params = std::move(Params);
269 WasmSym->setSignature(Signature);
270
271 return WasmSym;
272}
273
274void WebAssemblyAsmPrinter::emitSymbolType(const MCSymbolWasm *Sym) {
275 std::optional<wasm::WasmSymbolType> WasmTy = Sym->getType();
276 if (!WasmTy)
277 return;
278
279 switch (*WasmTy) {
280 case wasm::WASM_SYMBOL_TYPE_GLOBAL:
281 getTargetStreamer()->emitGlobalType(Sym);
282 break;
283 case wasm::WASM_SYMBOL_TYPE_TAG:
284 getTargetStreamer()->emitTagType(Sym);
285 break;
286 case wasm::WASM_SYMBOL_TYPE_TABLE:
287 getTargetStreamer()->emitTableType(Sym);
288 break;
289 default:
290 break; // We only handle globals, tags and tables here
291 }
292}
293
294void WebAssemblyAsmPrinter::emitDecls(const Module &M) {
295 if (signaturesEmitted)
296 return;
297 signaturesEmitted = true;
298
299 // Normally symbols for globals get discovered as the MI gets lowered,
300 // but we need to know about them ahead of time. This will however,
301 // only find symbols that have been used. Unused symbols from globals will
302 // not be found here.
303 MachineModuleInfoWasm &MMIW = MMI->getObjFileInfo<MachineModuleInfoWasm>();
304 for (StringRef Name : MMIW.MachineSymbolsUsed) {
305 auto *WasmSym = static_cast<MCSymbolWasm *>(getOrCreateWasmSymbol(Name));
306 if (WasmSym->isFunction()) {
307 // TODO(wvo): is there any case where this overlaps with the call to
308 // emitFunctionType in the loop below?
309 getTargetStreamer()->emitFunctionType(Sym: WasmSym);
310 }
311 }
312
313 for (auto &It : OutContext.getSymbols()) {
314 // Emit .globaltype, .tagtype, or .tabletype declarations for extern
315 // declarations, i.e. those that have only been declared (but not defined)
316 // in the current module
317 auto Sym = static_cast<MCSymbolWasm *>(It.getValue().Symbol);
318 if (Sym && !Sym->isDefined())
319 emitSymbolType(Sym);
320 }
321
322 DenseSet<MCSymbol *> InvokeSymbols;
323 for (const auto &F : M) {
324 if (F.isIntrinsic())
325 continue;
326
327 // Emit function type info for all functions. This will emit duplicate
328 // information for defined functions (which already have function type
329 // info emitted alongside their definition), but this is necessary in
330 // order to enable the single-pass WebAssemblyAsmTypeCheck to succeed.
331 SmallVector<MVT, 4> Results;
332 SmallVector<MVT, 4> Params;
333 computeSignatureVTs(Ty: F.getFunctionType(), TargetFunc: &F, ContextFunc: F, TM, Params, Results);
334 // At this point these MCSymbols may or may not have been created already
335 // and thus also contain a signature, but we need to get the signature
336 // anyway here in case it is an invoke that has not yet been created. We
337 // will discard it later if it turns out not to be necessary.
338 auto Signature = signatureFromMVTs(Ctx&: OutContext, Results, Params);
339 bool InvokeDetected = false;
340 auto *Sym = getMCSymbolForFunction(F: &F, Sig: Signature, InvokeDetected);
341
342 // Multiple functions can be mapped to the same invoke symbol. For
343 // example, two IR functions '__invoke_void_i8*' and '__invoke_void_i32'
344 // are both mapped to '__invoke_vi'. We keep them in a set once we emit an
345 // Emscripten EH symbol so we don't emit the same symbol twice.
346 if (InvokeDetected && !InvokeSymbols.insert(V: Sym).second)
347 continue;
348
349 Sym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
350 if (!Sym->getSignature()) {
351 Sym->setSignature(Signature);
352 }
353
354 getTargetStreamer()->emitFunctionType(Sym);
355
356 if (F.hasFnAttribute(Kind: "wasm-import-module")) {
357 StringRef Name =
358 F.getFnAttribute(Kind: "wasm-import-module").getValueAsString();
359 Sym->setImportModule(OutContext.allocateString(s: Name));
360 getTargetStreamer()->emitImportModule(Sym, ImportModule: Name);
361 }
362 if (F.hasFnAttribute(Kind: "wasm-import-name")) {
363 // If this is a converted Emscripten EH/SjLj symbol, we shouldn't use
364 // the original function name but the converted symbol name.
365 StringRef Name =
366 InvokeDetected
367 ? Sym->getName()
368 : F.getFnAttribute(Kind: "wasm-import-name").getValueAsString();
369 Sym->setImportName(OutContext.allocateString(s: Name));
370 getTargetStreamer()->emitImportName(Sym, ImportName: Name);
371 }
372
373 if (F.hasFnAttribute(Kind: "wasm-export-name")) {
374 auto *Sym = static_cast<MCSymbolWasm *>(getSymbol(GV: &F));
375 StringRef Name = F.getFnAttribute(Kind: "wasm-export-name").getValueAsString();
376 Sym->setExportName(OutContext.allocateString(s: Name));
377 getTargetStreamer()->emitExportName(Sym, ExportName: Name);
378 }
379 }
380}
381
382void WebAssemblyAsmPrinter::emitEndOfAsmFile(Module &M) {
383 // This is required to emit external declarations (like .functypes) when
384 // no functions are defined in the compilation unit and therefore,
385 // emitDecls() is not called until now.
386 emitDecls(M);
387
388 // When a function's address is taken, a TABLE_INDEX relocation is emitted
389 // against the function symbol at the use site. However the relocation
390 // doesn't explicitly refer to the table. In the future we may want to
391 // define a new kind of reloc against both the function and the table, so
392 // that the linker can see that the function symbol keeps the table alive,
393 // but for now manually mark the table as live.
394 for (const auto &F : M) {
395 if (!F.isIntrinsic() && F.hasAddressTaken()) {
396 MCSymbolWasm *FunctionTable =
397 WebAssembly::getOrCreateFunctionTableSymbol(Ctx&: OutContext, Subtarget);
398 OutStreamer->emitSymbolAttribute(Symbol: FunctionTable, Attribute: MCSA_NoDeadStrip);
399 break;
400 }
401 }
402
403 for (const auto &G : M.globals()) {
404 if (!G.hasInitializer() && G.hasExternalLinkage() &&
405 !WebAssembly::isWasmVarAddressSpace(AS: G.getAddressSpace()) &&
406 G.getValueType()->isSized()) {
407 uint16_t Size = G.getGlobalSize(DL: M.getDataLayout());
408 OutStreamer->emitELFSize(Symbol: getSymbol(GV: &G),
409 Value: MCConstantExpr::create(Value: Size, Ctx&: OutContext));
410 }
411 }
412
413 if (const NamedMDNode *Named = M.getNamedMetadata(Name: "wasm.custom_sections")) {
414 for (const Metadata *MD : Named->operands()) {
415 const auto *Tuple = dyn_cast<MDTuple>(Val: MD);
416 if (!Tuple || Tuple->getNumOperands() != 2)
417 continue;
418 const MDString *Name = dyn_cast<MDString>(Val: Tuple->getOperand(I: 0));
419 const MDString *Contents = dyn_cast<MDString>(Val: Tuple->getOperand(I: 1));
420 if (!Name || !Contents)
421 continue;
422
423 OutStreamer->pushSection();
424 std::string SectionName = (".custom_section." + Name->getString()).str();
425 MCSectionWasm *MySection =
426 OutContext.getWasmSection(Section: SectionName, K: SectionKind::getMetadata());
427 OutStreamer->switchSection(Section: MySection);
428 OutStreamer->emitBytes(Data: Contents->getString());
429 OutStreamer->popSection();
430 }
431 }
432
433 EmitProducerInfo(M);
434 EmitTargetFeatures(M);
435 EmitFunctionAttributes(M);
436}
437
438void WebAssemblyAsmPrinter::EmitProducerInfo(Module &M) {
439 llvm::SmallVector<std::pair<std::string, std::string>, 4> Languages;
440 if (const NamedMDNode *Debug = M.getNamedMetadata(Name: "llvm.dbg.cu")) {
441 llvm::SmallSet<StringRef, 4> SeenLanguages;
442 for (size_t I = 0, E = Debug->getNumOperands(); I < E; ++I) {
443 const auto *CU = cast<DICompileUnit>(Val: Debug->getOperand(i: I));
444 StringRef Language =
445 dwarf::LanguageString(Language: CU->getSourceLanguage().getUnversionedName());
446
447 Language.consume_front(Prefix: "DW_LANG_");
448 if (SeenLanguages.insert(V: Language).second)
449 Languages.emplace_back(Args: Language.str(), Args: "");
450 }
451 }
452
453 llvm::SmallVector<std::pair<std::string, std::string>, 4> Tools;
454 if (const NamedMDNode *Ident = M.getNamedMetadata(Name: "llvm.ident")) {
455 llvm::SmallSet<StringRef, 4> SeenTools;
456 for (size_t I = 0, E = Ident->getNumOperands(); I < E; ++I) {
457 const auto *S = cast<MDString>(Val: Ident->getOperand(i: I)->getOperand(I: 0));
458 std::pair<StringRef, StringRef> Field = S->getString().split(Separator: "version");
459 StringRef Name = Field.first.trim();
460 StringRef Version = Field.second.trim();
461 if (SeenTools.insert(V: Name).second)
462 Tools.emplace_back(Args: Name.str(), Args: Version.str());
463 }
464 }
465
466 int FieldCount = int(!Languages.empty()) + int(!Tools.empty());
467 if (FieldCount != 0) {
468 MCSectionWasm *Producers = OutContext.getWasmSection(
469 Section: ".custom_section.producers", K: SectionKind::getMetadata());
470 OutStreamer->pushSection();
471 OutStreamer->switchSection(Section: Producers);
472 OutStreamer->emitULEB128IntValue(Value: FieldCount);
473 for (auto &Producers : {std::make_pair(x: "language", y: &Languages),
474 std::make_pair(x: "processed-by", y: &Tools)}) {
475 if (Producers.second->empty())
476 continue;
477 OutStreamer->emitULEB128IntValue(Value: strlen(s: Producers.first));
478 OutStreamer->emitBytes(Data: Producers.first);
479 OutStreamer->emitULEB128IntValue(Value: Producers.second->size());
480 for (auto &Producer : *Producers.second) {
481 OutStreamer->emitULEB128IntValue(Value: Producer.first.size());
482 OutStreamer->emitBytes(Data: Producer.first);
483 OutStreamer->emitULEB128IntValue(Value: Producer.second.size());
484 OutStreamer->emitBytes(Data: Producer.second);
485 }
486 }
487 OutStreamer->popSection();
488 }
489}
490
491void WebAssemblyAsmPrinter::EmitTargetFeatures(Module &M) {
492 struct FeatureEntry {
493 uint8_t Prefix;
494 std::string Name;
495 };
496
497 // Read target features and linkage policies from module metadata
498 SmallVector<FeatureEntry, 4> EmittedFeatures;
499 auto EmitFeature = [&](std::string Feature) {
500 std::string MDKey = (StringRef("wasm-feature-") + Feature).str();
501 Metadata *Policy = M.getModuleFlag(Key: MDKey);
502 if (Policy == nullptr)
503 return;
504
505 FeatureEntry Entry;
506 Entry.Prefix = 0;
507 Entry.Name = Feature;
508
509 if (auto *MD = cast<ConstantAsMetadata>(Val: Policy))
510 if (auto *I = cast<ConstantInt>(Val: MD->getValue()))
511 Entry.Prefix = I->getZExtValue();
512
513 // Silently ignore invalid metadata
514 if (Entry.Prefix != wasm::WASM_FEATURE_PREFIX_USED &&
515 Entry.Prefix != wasm::WASM_FEATURE_PREFIX_DISALLOWED)
516 return;
517
518 EmittedFeatures.push_back(Elt: Entry);
519 };
520
521 for (const SubtargetFeatureKV &KV : WebAssemblyFeatureKV) {
522 EmitFeature(KV.Key);
523 }
524 // This pseudo-feature tells the linker whether shared memory would be safe
525 EmitFeature("shared-mem");
526
527 // This is an "architecture", not a "feature", but we emit it as such for
528 // the benefit of tools like Binaryen and consistency with other producers.
529 // FIXME: Subtarget is null here, so can't Subtarget->hasAddr64() ?
530 if (M.getDataLayout().getPointerSize() == 8) {
531 // Can't use EmitFeature since "wasm-feature-memory64" is not a module
532 // flag.
533 EmittedFeatures.push_back(Elt: {.Prefix: wasm::WASM_FEATURE_PREFIX_USED, .Name: "memory64"});
534 }
535
536 if (EmittedFeatures.size() == 0)
537 return;
538
539 // Emit features and linkage policies into the "target_features" section
540 MCSectionWasm *FeaturesSection = OutContext.getWasmSection(
541 Section: ".custom_section.target_features", K: SectionKind::getMetadata());
542 OutStreamer->pushSection();
543 OutStreamer->switchSection(Section: FeaturesSection);
544
545 OutStreamer->emitULEB128IntValue(Value: EmittedFeatures.size());
546 for (auto &F : EmittedFeatures) {
547 OutStreamer->emitIntValue(Value: F.Prefix, Size: 1);
548 OutStreamer->emitULEB128IntValue(Value: F.Name.size());
549 OutStreamer->emitBytes(Data: F.Name);
550 }
551
552 OutStreamer->popSection();
553}
554
555void WebAssemblyAsmPrinter::EmitFunctionAttributes(Module &M) {
556 auto V = M.getNamedGlobal(Name: "llvm.global.annotations");
557 if (!V)
558 return;
559
560 // Group all the custom attributes by name.
561 MapVector<StringRef, SmallVector<MCSymbol *, 4>> CustomSections;
562 const ConstantArray *CA = cast<ConstantArray>(Val: V->getOperand(i_nocapture: 0));
563 for (Value *Op : CA->operands()) {
564 auto *CS = cast<ConstantStruct>(Val: Op);
565 // The first field is a pointer to the annotated variable.
566 Value *AnnotatedVar = CS->getOperand(i_nocapture: 0)->stripPointerCasts();
567 // Only annotated functions are supported for now.
568 if (!isa<Function>(Val: AnnotatedVar))
569 continue;
570 auto *F = cast<Function>(Val: AnnotatedVar);
571
572 // The second field is a pointer to a global annotation string.
573 auto *GV = cast<GlobalVariable>(Val: CS->getOperand(i_nocapture: 1)->stripPointerCasts());
574 StringRef AnnotationString;
575 getConstantStringInfo(V: GV, Str&: AnnotationString);
576 auto *Sym = static_cast<MCSymbolWasm *>(getSymbol(GV: F));
577 CustomSections[AnnotationString].push_back(Elt: Sym);
578 }
579
580 // Emit a custom section for each unique attribute.
581 for (const auto &[Name, Symbols] : CustomSections) {
582 MCSectionWasm *CustomSection = OutContext.getWasmSection(
583 Section: ".custom_section.llvm.func_attr.annotate." + Name, K: SectionKind::getMetadata());
584 OutStreamer->pushSection();
585 OutStreamer->switchSection(Section: CustomSection);
586
587 for (auto &Sym : Symbols) {
588 OutStreamer->emitValue(
589 Value: MCSymbolRefExpr::create(Symbol: Sym, specifier: WebAssembly::S_FUNCINDEX, Ctx&: OutContext),
590 Size: 4);
591 }
592 OutStreamer->popSection();
593 }
594}
595
596void WebAssemblyAsmPrinter::emitConstantPool() {
597 emitDecls(M: *MMI->getModule());
598 assert(MF->getConstantPool()->getConstants().empty() &&
599 "WebAssembly disables constant pools");
600}
601
602void WebAssemblyAsmPrinter::emitJumpTableInfo() {
603 // Nothing to do; jump tables are incorporated into the instruction stream.
604}
605
606void WebAssemblyAsmPrinter::emitFunctionBodyStart() {
607 const Function &F = MF->getFunction();
608 SmallVector<MVT, 1> ResultVTs;
609 SmallVector<MVT, 4> ParamVTs;
610 computeSignatureVTs(Ty: F.getFunctionType(), TargetFunc: &F, ContextFunc: F, TM, Params&: ParamVTs, Results&: ResultVTs);
611
612 auto Signature = signatureFromMVTs(Ctx&: OutContext, Results: ResultVTs, Params: ParamVTs);
613 auto *WasmSym = static_cast<MCSymbolWasm *>(CurrentFnSym);
614 WasmSym->setSignature(Signature);
615 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
616
617 getTargetStreamer()->emitFunctionType(Sym: WasmSym);
618
619 // Emit the function index.
620 if (MDNode *Idx = F.getMetadata(Kind: "wasm.index")) {
621 assert(Idx->getNumOperands() == 1);
622
623 getTargetStreamer()->emitIndIdx(Value: AsmPrinter::lowerConstant(
624 CV: cast<ConstantAsMetadata>(Val: Idx->getOperand(I: 0))->getValue()));
625 }
626
627 SmallVector<wasm::ValType, 16> Locals;
628 valTypesFromMVTs(In: MFI->getLocals(), Out&: Locals);
629 getTargetStreamer()->emitLocal(Types: Locals);
630
631 AsmPrinter::emitFunctionBodyStart();
632}
633
634void WebAssemblyAsmPrinter::emitInstruction(const MachineInstr *MI) {
635 LLVM_DEBUG(dbgs() << "EmitInstruction: " << *MI << '\n');
636 WebAssembly_MC::verifyInstructionPredicates(Opcode: MI->getOpcode(),
637 Features: Subtarget->getFeatureBits());
638
639 switch (MI->getOpcode()) {
640 case WebAssembly::ARGUMENT_i32:
641 case WebAssembly::ARGUMENT_i32_S:
642 case WebAssembly::ARGUMENT_i64:
643 case WebAssembly::ARGUMENT_i64_S:
644 case WebAssembly::ARGUMENT_f32:
645 case WebAssembly::ARGUMENT_f32_S:
646 case WebAssembly::ARGUMENT_f64:
647 case WebAssembly::ARGUMENT_f64_S:
648 case WebAssembly::ARGUMENT_v16i8:
649 case WebAssembly::ARGUMENT_v16i8_S:
650 case WebAssembly::ARGUMENT_v8i16:
651 case WebAssembly::ARGUMENT_v8i16_S:
652 case WebAssembly::ARGUMENT_v4i32:
653 case WebAssembly::ARGUMENT_v4i32_S:
654 case WebAssembly::ARGUMENT_v2i64:
655 case WebAssembly::ARGUMENT_v2i64_S:
656 case WebAssembly::ARGUMENT_v4f32:
657 case WebAssembly::ARGUMENT_v4f32_S:
658 case WebAssembly::ARGUMENT_v2f64:
659 case WebAssembly::ARGUMENT_v2f64_S:
660 case WebAssembly::ARGUMENT_v8f16:
661 case WebAssembly::ARGUMENT_v8f16_S:
662 // These represent values which are live into the function entry, so there's
663 // no instruction to emit.
664 break;
665 case WebAssembly::FALLTHROUGH_RETURN: {
666 // These instructions represent the implicit return at the end of a
667 // function body.
668 if (isVerbose()) {
669 OutStreamer->AddComment(T: "fallthrough-return");
670 OutStreamer->addBlankLine();
671 }
672 break;
673 }
674 case WebAssembly::COMPILER_FENCE:
675 // This is a compiler barrier that prevents instruction reordering during
676 // backend compilation, and should not be emitted.
677 break;
678 case WebAssembly::CATCH:
679 case WebAssembly::CATCH_S:
680 case WebAssembly::CATCH_REF:
681 case WebAssembly::CATCH_REF_S:
682 case WebAssembly::CATCH_ALL:
683 case WebAssembly::CATCH_ALL_S:
684 case WebAssembly::CATCH_ALL_REF:
685 case WebAssembly::CATCH_ALL_REF_S:
686 // These are pseudo instructions to represent catch clauses in try_table
687 // instruction to simulate block return values.
688 break;
689 default: {
690 WebAssemblyMCInstLower MCInstLowering(OutContext, *this);
691 MCInst TmpInst;
692 MCInstLowering.lower(MI, OutMI&: TmpInst);
693 EmitToStreamer(S&: *OutStreamer, Inst: TmpInst);
694 break;
695 }
696 }
697}
698
699bool WebAssemblyAsmPrinter::PrintAsmOperand(const MachineInstr *MI,
700 unsigned OpNo,
701 const char *ExtraCode,
702 raw_ostream &OS) {
703 // First try the generic code, which knows about modifiers like 'c' and 'n'.
704 if (!AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, OS))
705 return false;
706
707 if (!ExtraCode) {
708 const MachineOperand &MO = MI->getOperand(i: OpNo);
709 switch (MO.getType()) {
710 case MachineOperand::MO_Immediate:
711 OS << MO.getImm();
712 return false;
713 case MachineOperand::MO_Register:
714 // FIXME: only opcode that still contains registers, as required by
715 // MachineInstr::getDebugVariable().
716 assert(MI->getOpcode() == WebAssembly::INLINEASM);
717 OS << regToString(MO);
718 return false;
719 case MachineOperand::MO_GlobalAddress:
720 PrintSymbolOperand(MO, OS);
721 return false;
722 case MachineOperand::MO_ExternalSymbol:
723 GetExternalSymbolSymbol(Sym: MO.getSymbolName())->print(OS, MAI);
724 printOffset(Offset: MO.getOffset(), OS);
725 return false;
726 case MachineOperand::MO_MachineBasicBlock:
727 MO.getMBB()->getSymbol()->print(OS, MAI);
728 return false;
729 default:
730 break;
731 }
732 }
733
734 return true;
735}
736
737bool WebAssemblyAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
738 unsigned OpNo,
739 const char *ExtraCode,
740 raw_ostream &OS) {
741 // The current approach to inline asm is that "r" constraints are expressed
742 // as local indices, rather than values on the operand stack. This simplifies
743 // using "r" as it eliminates the need to push and pop the values in a
744 // particular order, however it also makes it impossible to have an "m"
745 // constraint. So we don't support it.
746
747 return AsmPrinter::PrintAsmMemoryOperand(MI, OpNo, ExtraCode, OS);
748}
749
750char WebAssemblyAsmPrinter::ID = 0;
751
752INITIALIZE_PASS(WebAssemblyAsmPrinter, "webassembly-asm-printer",
753 "WebAssembly Assmebly Printer", false, false)
754
755// Force static initialization.
756extern "C" LLVM_ABI LLVM_EXTERNAL_VISIBILITY void
757LLVMInitializeWebAssemblyAsmPrinter() {
758 RegisterAsmPrinter<WebAssemblyAsmPrinter> X(getTheWebAssemblyTarget32());
759 RegisterAsmPrinter<WebAssemblyAsmPrinter> Y(getTheWebAssemblyTarget64());
760}
761