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 // Prefer the "exception-model" module flag, else the TargetOptions default.
169 ExceptionHandling EM = F->getParent()->getExceptionModel();
170 if (EM == ExceptionHandling::Default)
171 EM = TM.getExceptionModel();
172 const bool EnableEmEH =
173 EM == ExceptionHandling::Emscripten || WebAssembly::WasmEnableEmSjLj;
174 if (EnableEmEH && isEmscriptenInvokeName(Name: F->getName())) {
175 assert(Sig);
176 InvokeDetected = true;
177 if (Sig->Returns.size() > 1) {
178 std::string Msg =
179 "Emscripten EH/SjLj does not support multivalue returns: " +
180 std::string(F->getName()) + ": " +
181 WebAssembly::signatureToString(Sig);
182 report_fatal_error(reason: Twine(Msg));
183 }
184 WasmSym = static_cast<MCSymbolWasm *>(
185 GetExternalSymbolSymbol(Sym: getEmscriptenInvokeSymbolName(Sig)));
186 } else {
187 WasmSym = static_cast<MCSymbolWasm *>(getSymbol(GV: F));
188 }
189 return WasmSym;
190}
191
192void WebAssemblyAsmPrinter::emitGlobalVariable(const GlobalVariable *GV) {
193 if (GV->hasAttribute(Kind: "wasm-import-module") ||
194 GV->hasAttribute(Kind: "wasm-import-name")) {
195 if (!GV->isDeclaration()) {
196 OutContext.reportError(L: SMLoc(), Msg: "definition of global '" + GV->getName() +
197 "' cannot have import attribute");
198 return;
199 }
200 if (!WebAssembly::isWasmVarAddressSpace(AS: GV->getAddressSpace())) {
201 OutContext.reportError(L: SMLoc(),
202 Msg: "imported global '" + GV->getName() +
203 "' must be in a wasm variable address space");
204 return;
205 }
206 }
207 if (!WebAssembly::isWasmVarAddressSpace(AS: GV->getAddressSpace())) {
208 if (GV->hasAttribute(Kind: "wasm-export-name")) {
209 auto *Sym = static_cast<MCSymbolWasm *>(getSymbol(GV));
210 StringRef Name = GV->getAttribute(Kind: "wasm-export-name").getValueAsString();
211 Sym->setExportName(OutContext.allocateString(s: Name));
212 getTargetStreamer()->emitExportName(Sym, ExportName: Name);
213 }
214 AsmPrinter::emitGlobalVariable(GV);
215 return;
216 }
217
218 assert(!GV->isThreadLocal());
219 auto *Sym = static_cast<MCSymbolWasm *>(getSymbol(GV));
220 if (!Sym->getType()) {
221 SmallVector<MVT, 1> VTs;
222 Type *GlobalVT = GV->getValueType();
223 // Function-specific subtargets are not needed here: WebAssembly
224 // coalesces features before isel, so use the TargetMachine's
225 // module-wide subtarget to compute legal value types.
226 auto &WasmTM = static_cast<const WebAssemblyTargetMachine &>(TM);
227 const WebAssemblySubtarget *ST = WasmTM.getSubtargetImpl(
228 CPU: WasmTM.getTargetCPU(), FS: WasmTM.getTargetFeatureString());
229 const WebAssemblyTargetLowering &TLI = *ST->getTargetLowering();
230 computeLegalValueVTs(TLI, Ctx&: GV->getParent()->getContext(),
231 DL: GV->getDataLayout(), Ty: GlobalVT, ValueVTs&: VTs);
232
233 WebAssembly::wasmSymbolSetType(Sym, GlobalVT, VTs,
234 /*Mutable=*/!GV->isConstant());
235 }
236
237 emitVisibility(Sym, Visibility: GV->getVisibility(), IsDefinition: !GV->isDeclaration());
238 emitSymbolType(Sym);
239 if (GV->isDeclaration()) {
240 if (GV->hasAttribute(Kind: "wasm-import-module")) {
241 StringRef ImportModule =
242 GV->getAttribute(Kind: "wasm-import-module").getValueAsString();
243 Sym->setImportModule(OutContext.allocateString(s: ImportModule));
244 getTargetStreamer()->emitImportModule(Sym, ImportModule);
245 }
246 if (GV->hasAttribute(Kind: "wasm-import-name")) {
247 StringRef ImportName =
248 GV->getAttribute(Kind: "wasm-import-name").getValueAsString();
249 Sym->setImportName(OutContext.allocateString(s: ImportName));
250 getTargetStreamer()->emitImportName(Sym, ImportName);
251 }
252 }
253 if (GV->hasInitializer()) {
254 assert(getSymbolPreferLocal(*GV) == Sym);
255 emitLinkage(GV, GVSym: Sym);
256 OutStreamer->emitLabel(Symbol: Sym);
257 if (GV->hasAttribute(Kind: "wasm-export-name")) {
258 StringRef ExportName =
259 GV->getAttribute(Kind: "wasm-export-name").getValueAsString();
260 Sym->setExportName(OutContext.allocateString(s: ExportName));
261 getTargetStreamer()->emitExportName(Sym, ExportName);
262 }
263 // TODO: Actually emit the initializer value. Otherwise the global has the
264 // default value for its type (0, ref.null, etc).
265 OutStreamer->addBlankLine();
266 }
267}
268
269MCSymbol *WebAssemblyAsmPrinter::getOrCreateWasmSymbol(StringRef Name) {
270 auto *WasmSym = static_cast<MCSymbolWasm *>(GetExternalSymbolSymbol(Sym: Name));
271 // May be called multiple times, so early out.
272 if (WasmSym->getType())
273 return WasmSym;
274
275 const WebAssemblySubtarget &Subtarget = getSubtarget();
276
277 // Except for certain known symbols, all symbols used by CodeGen are
278 // functions. It's OK to hardcode knowledge of specific symbols here; this
279 // method is precisely there for fetching the signatures of known
280 // Clang-provided symbols.
281 if (Name == "__stack_pointer" || Name == "__tls_base" ||
282 Name == "__memory_base" || Name == "__table_base" ||
283 Name == "__tls_size" || Name == "__tls_align") {
284 bool Mutable = Name == "__stack_pointer" || Name == "__tls_base";
285 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_GLOBAL);
286 WasmSym->setGlobalType(wasm::WasmGlobalType{
287 .Type: uint8_t(Subtarget.hasAddr64() ? wasm::WASM_TYPE_I64
288 : wasm::WASM_TYPE_I32),
289 .Mutable: Mutable});
290 return WasmSym;
291 }
292
293 if (Name.starts_with(Prefix: "GCC_except_table")) {
294 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_DATA);
295 return WasmSym;
296 }
297
298 SmallVector<wasm::ValType, 4> Returns;
299 SmallVector<wasm::ValType, 4> Params;
300 if (Name == "__cpp_exception" || Name == "__c_longjmp") {
301 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_TAG);
302 WasmSym->setExternal(true);
303
304 // Currently both C++ exceptions and C longjmps have a single pointer type
305 // param. For C++ exceptions it is a pointer to an exception object, and for
306 // C longjmps it is pointer to a struct that contains a setjmp buffer and a
307 // longjmp return value. We may consider using multiple value parameters for
308 // longjmps later when multivalue support is ready.
309 wasm::ValType AddrType =
310 Subtarget.hasAddr64() ? wasm::ValType::I64 : wasm::ValType::I32;
311 Params.push_back(Elt: AddrType);
312 } else if (Name == "__wasm_get_stack_pointer" ||
313 Name == "__wasm_get_tls_base") {
314 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
315 Returns.push_back(Elt: wasm::ValType::I32);
316 } else if (Name == "__wasm_set_stack_pointer" ||
317 Name == "__wasm_set_tls_base") {
318 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
319 Params.push_back(Elt: wasm::ValType::I32);
320 } else { // Function symbols
321 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
322 WebAssembly::getLibcallSignature(Subtarget, Name, Rets&: Returns, Params);
323 }
324 auto Signature = OutContext.createWasmSignature();
325 Signature->Returns = std::move(Returns);
326 Signature->Params = std::move(Params);
327 WasmSym->setSignature(Signature);
328
329 return WasmSym;
330}
331
332void WebAssemblyAsmPrinter::emitSymbolType(const MCSymbolWasm *Sym) {
333 std::optional<wasm::WasmSymbolType> WasmTy = Sym->getType();
334 if (!WasmTy)
335 return;
336
337 switch (*WasmTy) {
338 case wasm::WASM_SYMBOL_TYPE_GLOBAL:
339 getTargetStreamer()->emitGlobalType(Sym);
340 break;
341 case wasm::WASM_SYMBOL_TYPE_TAG:
342 getTargetStreamer()->emitTagType(Sym);
343 break;
344 case wasm::WASM_SYMBOL_TYPE_TABLE:
345 getTargetStreamer()->emitTableType(Sym);
346 break;
347 default:
348 break; // We only handle globals, tags and tables here
349 }
350}
351
352void WebAssemblyAsmPrinter::emitDecls(const Module &M) {
353 if (signaturesEmitted)
354 return;
355 signaturesEmitted = true;
356
357 // Normally symbols for globals get discovered as the MI gets lowered,
358 // but we need to know about them ahead of time. This will however,
359 // only find symbols that have been used. Unused symbols from globals will
360 // not be found here.
361 MachineModuleInfoWasm &MMIW = MMI->getObjFileInfo<MachineModuleInfoWasm>();
362 for (StringRef Name : MMIW.MachineSymbolsUsed) {
363 auto *WasmSym = static_cast<MCSymbolWasm *>(getOrCreateWasmSymbol(Name));
364 if (WasmSym->isFunction()) {
365 // TODO(wvo): is there any case where this overlaps with the call to
366 // emitFunctionType in the loop below?
367 getTargetStreamer()->emitFunctionType(Sym: WasmSym);
368 }
369 }
370
371 for (auto &It : OutContext.getSymbols()) {
372 // Emit .globaltype, .tagtype, or .tabletype declarations for extern
373 // declarations, i.e. those that have only been declared (but not defined)
374 // in the current module
375 auto Sym = static_cast<MCSymbolWasm *>(It.getValue().Symbol);
376 if (Sym && !Sym->isDefined())
377 emitSymbolType(Sym);
378 }
379
380 // We handle `__funcref_call_table` specially here.
381 //
382 // Unlike most table symbols, which are attached to a `GlobalVariable`
383 // this one is a directly created, freestanding MCSymbol, much like
384 // `__indirect_function_table`. However, given that the table is always
385 // identical (single element, default initialized), we declare it
386 // weak in each object, and define it here rather than in the linker.
387 //
388 // TODO: consider moving this definition elsewhere, or doing away with
389 // the table entirely (in favor of `call_ref` exclusively).
390 {
391 StringRef Name = "__funcref_call_table";
392 auto *Sym = static_cast<MCSymbolWasm *>(OutContext.lookupSymbol(Name));
393 if (Sym) {
394 if (!Sym->isFunctionTable())
395 OutContext.reportError(L: SMLoc(), Msg: "symbol is not a wasm funcref table");
396
397 // symbol is declared weak in `getOrCreateFuncrefCallTableSymbol`
398 assert(Sym->isWeak());
399 OutStreamer->emitSymbolAttribute(Symbol: Sym, Attribute: MCSA_Weak);
400
401 // Make sure we haven't already emitted it for whatever reason.
402 assert(!Sym->isDefined());
403
404 // Actually define the symbol.
405 // Confusingly enough, `emitLabel` is what "defines" a MCSymbol.
406 // Provides it a fragment, so that it `!isUndefined`
407 OutStreamer->emitLabel(Symbol: Sym);
408 // No initializer needed. Default ref.null is good
409 OutStreamer->addBlankLine();
410 }
411 }
412
413 DenseSet<MCSymbol *> InvokeSymbols;
414 for (const auto &F : M) {
415 if (F.isIntrinsic())
416 continue;
417
418 // Emit function type info for all functions. This will emit duplicate
419 // information for defined functions (which already have function type
420 // info emitted alongside their definition), but this is necessary in
421 // order to enable the single-pass WebAssemblyAsmTypeCheck to succeed.
422 SmallVector<MVT, 4> Results;
423 SmallVector<MVT, 4> Params;
424 computeSignatureVTs(Ty: F.getFunctionType(), TargetFunc: &F, ContextFunc: F, TM, Params, Results);
425 // At this point these MCSymbols may or may not have been created already
426 // and thus also contain a signature, but we need to get the signature
427 // anyway here in case it is an invoke that has not yet been created. We
428 // will discard it later if it turns out not to be necessary.
429 auto Signature = signatureFromMVTs(Ctx&: OutContext, Results, Params);
430 bool InvokeDetected = false;
431 auto *Sym = getMCSymbolForFunction(F: &F, Sig: Signature, InvokeDetected);
432
433 // Multiple functions can be mapped to the same invoke symbol. For
434 // example, two IR functions '__invoke_void_i8*' and '__invoke_void_i32'
435 // are both mapped to '__invoke_vi'. We keep them in a set once we emit an
436 // Emscripten EH symbol so we don't emit the same symbol twice.
437 if (InvokeDetected && !InvokeSymbols.insert(V: Sym).second)
438 continue;
439
440 Sym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
441 if (!Sym->getSignature()) {
442 Sym->setSignature(Signature);
443 }
444
445 getTargetStreamer()->emitFunctionType(Sym);
446
447 if (F.hasFnAttribute(Kind: "wasm-import-module")) {
448 StringRef Name =
449 F.getFnAttribute(Kind: "wasm-import-module").getValueAsString();
450 Sym->setImportModule(OutContext.allocateString(s: Name));
451 getTargetStreamer()->emitImportModule(Sym, ImportModule: Name);
452 }
453 if (F.hasFnAttribute(Kind: "wasm-import-name")) {
454 // If this is a converted Emscripten EH/SjLj symbol, we shouldn't use
455 // the original function name but the converted symbol name.
456 StringRef Name =
457 InvokeDetected
458 ? Sym->getName()
459 : F.getFnAttribute(Kind: "wasm-import-name").getValueAsString();
460 Sym->setImportName(OutContext.allocateString(s: Name));
461 getTargetStreamer()->emitImportName(Sym, ImportName: Name);
462 }
463
464 if (F.hasFnAttribute(Kind: "wasm-export-name")) {
465 auto *Sym = static_cast<MCSymbolWasm *>(getSymbol(GV: &F));
466 StringRef Name = F.getFnAttribute(Kind: "wasm-export-name").getValueAsString();
467 Sym->setExportName(OutContext.allocateString(s: Name));
468 getTargetStreamer()->emitExportName(Sym, ExportName: Name);
469 }
470 }
471}
472
473void WebAssemblyAsmPrinter::emitEndOfAsmFile(Module &M) {
474 // This is required to emit external declarations (like .functypes) when
475 // no functions are defined in the compilation unit and therefore,
476 // emitDecls() is not called until now.
477 emitDecls(M);
478
479 // When a function's address is taken, a TABLE_INDEX relocation is emitted
480 // against the function symbol at the use site. However the relocation
481 // doesn't explicitly refer to the table. In the future we may want to
482 // define a new kind of reloc against both the function and the table, so
483 // that the linker can see that the function symbol keeps the table alive,
484 // but for now manually mark the table as live.
485 for (const auto &F : M) {
486 if (!F.isIntrinsic() && F.hasAddressTaken()) {
487 MCSymbolWasm *FunctionTable =
488 WebAssembly::getOrCreateFunctionTableSymbol(Ctx&: OutContext, Subtarget);
489 OutStreamer->emitSymbolAttribute(Symbol: FunctionTable, Attribute: MCSA_NoDeadStrip);
490 break;
491 }
492 }
493
494 for (const auto &G : M.globals()) {
495 if (!G.hasInitializer() && G.hasExternalLinkage() &&
496 !WebAssembly::isWasmVarAddressSpace(AS: G.getAddressSpace()) &&
497 G.getValueType()->isSized()) {
498 uint16_t Size = G.getGlobalSize(DL: M.getDataLayout());
499 OutStreamer->emitELFSize(Symbol: getSymbol(GV: &G),
500 Value: MCConstantExpr::create(Value: Size, Ctx&: OutContext));
501 }
502 }
503
504 if (const NamedMDNode *Named = M.getNamedMetadata(Name: "wasm.custom_sections")) {
505 for (const Metadata *MD : Named->operands()) {
506 const auto *Tuple = dyn_cast<MDTuple>(Val: MD);
507 if (!Tuple || Tuple->getNumOperands() != 2)
508 continue;
509 const MDString *Name = dyn_cast<MDString>(Val: Tuple->getOperand(I: 0));
510 const MDString *Contents = dyn_cast<MDString>(Val: Tuple->getOperand(I: 1));
511 if (!Name || !Contents)
512 continue;
513
514 OutStreamer->pushSection();
515 std::string SectionName = (".custom_section." + Name->getString()).str();
516 MCSectionWasm *MySection =
517 OutContext.getWasmSection(Section: SectionName, K: SectionKind::getMetadata());
518 OutStreamer->switchSection(Section: MySection);
519 OutStreamer->emitBytes(Data: Contents->getString());
520 OutStreamer->popSection();
521 }
522 }
523
524 EmitProducerInfo(M);
525 EmitTargetFeatures(M);
526 EmitFunctionAttributes(M);
527}
528
529void WebAssemblyAsmPrinter::EmitProducerInfo(Module &M) {
530 llvm::SmallVector<std::pair<std::string, std::string>, 4> Languages;
531 if (const NamedMDNode *Debug = M.getNamedMetadata(Name: "llvm.dbg.cu")) {
532 llvm::SmallSet<StringRef, 4> SeenLanguages;
533 for (size_t I = 0, E = Debug->getNumOperands(); I < E; ++I) {
534 const auto *CU = cast<DICompileUnit>(Val: Debug->getOperand(i: I));
535 StringRef Language =
536 dwarf::LanguageString(Language: CU->getSourceLanguage().getUnversionedName());
537
538 Language.consume_front(Prefix: "DW_LANG_");
539 if (SeenLanguages.insert(V: Language).second)
540 Languages.emplace_back(Args: Language.str(), Args: "");
541 }
542 }
543
544 llvm::SmallVector<std::pair<std::string, std::string>, 4> Tools;
545 if (const NamedMDNode *Ident = M.getNamedMetadata(Name: "llvm.ident")) {
546 llvm::SmallSet<StringRef, 4> SeenTools;
547 for (size_t I = 0, E = Ident->getNumOperands(); I < E; ++I) {
548 const auto *S = cast<MDString>(Val: Ident->getOperand(i: I)->getOperand(I: 0));
549 std::pair<StringRef, StringRef> Field = S->getString().split(Separator: "version");
550 StringRef Name = Field.first.trim();
551 StringRef Version = Field.second.trim();
552 if (SeenTools.insert(V: Name).second)
553 Tools.emplace_back(Args: Name.str(), Args: Version.str());
554 }
555 }
556
557 int FieldCount = int(!Languages.empty()) + int(!Tools.empty());
558 if (FieldCount != 0) {
559 MCSectionWasm *Producers = OutContext.getWasmSection(
560 Section: ".custom_section.producers", K: SectionKind::getMetadata());
561 OutStreamer->pushSection();
562 OutStreamer->switchSection(Section: Producers);
563 OutStreamer->emitULEB128IntValue(Value: FieldCount);
564 for (auto &Producers : {std::make_pair(x: "language", y: &Languages),
565 std::make_pair(x: "processed-by", y: &Tools)}) {
566 if (Producers.second->empty())
567 continue;
568 OutStreamer->emitULEB128IntValue(Value: strlen(s: Producers.first));
569 OutStreamer->emitBytes(Data: Producers.first);
570 OutStreamer->emitULEB128IntValue(Value: Producers.second->size());
571 for (auto &Producer : *Producers.second) {
572 OutStreamer->emitULEB128IntValue(Value: Producer.first.size());
573 OutStreamer->emitBytes(Data: Producer.first);
574 OutStreamer->emitULEB128IntValue(Value: Producer.second.size());
575 OutStreamer->emitBytes(Data: Producer.second);
576 }
577 }
578 OutStreamer->popSection();
579 }
580}
581
582void WebAssemblyAsmPrinter::EmitTargetFeatures(Module &M) {
583 struct FeatureEntry {
584 uint8_t Prefix;
585 std::string Name;
586 };
587
588 // Read target features and linkage policies from module metadata
589 SmallVector<FeatureEntry, 4> EmittedFeatures;
590 auto EmitFeature = [&](std::string Feature) {
591 std::string MDKey = (StringRef("wasm-feature-") + Feature).str();
592 Metadata *Policy = M.getModuleFlag(Key: MDKey);
593 if (Policy == nullptr)
594 return;
595
596 FeatureEntry Entry;
597 Entry.Prefix = 0;
598 Entry.Name = Feature;
599
600 if (auto *MD = cast<ConstantAsMetadata>(Val: Policy))
601 if (auto *I = cast<ConstantInt>(Val: MD->getValue()))
602 Entry.Prefix = I->getZExtValue();
603
604 // Silently ignore invalid metadata
605 if (Entry.Prefix != wasm::WASM_FEATURE_PREFIX_USED &&
606 Entry.Prefix != wasm::WASM_FEATURE_PREFIX_DISALLOWED)
607 return;
608
609 EmittedFeatures.push_back(Elt: Entry);
610 };
611
612 // If we never compiled a single function, Subtarget is null.
613 if (!Subtarget) {
614 Subtarget = static_cast<WebAssemblyTargetMachine &>(TM).getSubtargetImpl(
615 CPU: TM.getTargetCPU(), FS: TM.getTargetFeatureString());
616 }
617 for (const SubtargetFeatureKV &KV : Subtarget->getAllProcessorFeatures()) {
618 EmitFeature(KV.key());
619 }
620 // This pseudo-feature tells the linker whether shared memory would be safe
621 EmitFeature("shared-mem");
622
623 // This is an "architecture", not a "feature", but we emit it as such for
624 // the benefit of tools like Binaryen and consistency with other producers.
625 if (Subtarget->hasAddr64()) {
626 // Can't use EmitFeature since "wasm-feature-memory64" is not a module
627 // flag.
628 EmittedFeatures.push_back(Elt: {.Prefix: wasm::WASM_FEATURE_PREFIX_USED, .Name: "memory64"});
629 }
630
631 if (EmittedFeatures.size() == 0)
632 return;
633
634 // Emit features and linkage policies into the "target_features" section
635 MCSectionWasm *FeaturesSection = OutContext.getWasmSection(
636 Section: ".custom_section.target_features", K: SectionKind::getMetadata());
637 OutStreamer->pushSection();
638 OutStreamer->switchSection(Section: FeaturesSection);
639
640 OutStreamer->emitULEB128IntValue(Value: EmittedFeatures.size());
641 for (auto &F : EmittedFeatures) {
642 OutStreamer->emitIntValue(Value: F.Prefix, Size: 1);
643 OutStreamer->emitULEB128IntValue(Value: F.Name.size());
644 OutStreamer->emitBytes(Data: F.Name);
645 }
646
647 OutStreamer->popSection();
648}
649
650void WebAssemblyAsmPrinter::EmitFunctionAttributes(Module &M) {
651 auto V = M.getNamedGlobal(Name: "llvm.global.annotations");
652 if (!V)
653 return;
654
655 // Group all the custom attributes by name.
656 MapVector<StringRef, SmallVector<MCSymbol *, 4>> CustomSections;
657 const ConstantArray *CA = cast<ConstantArray>(Val: V->getOperand(i_nocapture: 0));
658 for (Value *Op : CA->operands()) {
659 auto *CS = cast<ConstantStruct>(Val: Op);
660 // The first field is a pointer to the annotated variable.
661 Value *AnnotatedVar = CS->getOperand(i_nocapture: 0)->stripPointerCasts();
662 // Only annotated functions are supported for now.
663 if (!isa<Function>(Val: AnnotatedVar))
664 continue;
665 auto *F = cast<Function>(Val: AnnotatedVar);
666
667 // The second field is a pointer to a global annotation string.
668 auto *GV = cast<GlobalVariable>(Val: CS->getOperand(i_nocapture: 1)->stripPointerCasts());
669 StringRef AnnotationString;
670 getConstantStringInfo(V: GV, Str&: AnnotationString);
671 auto *Sym = static_cast<MCSymbolWasm *>(getSymbol(GV: F));
672 CustomSections[AnnotationString].push_back(Elt: Sym);
673 }
674
675 // Emit a custom section for each unique attribute.
676 for (const auto &[Name, Symbols] : CustomSections) {
677 MCSectionWasm *CustomSection = OutContext.getWasmSection(
678 Section: ".custom_section.llvm.func_attr.annotate." + Name, K: SectionKind::getMetadata());
679 OutStreamer->pushSection();
680 OutStreamer->switchSection(Section: CustomSection);
681
682 for (auto &Sym : Symbols) {
683 OutStreamer->emitValue(
684 Value: MCSymbolRefExpr::create(Symbol: Sym, specifier: WebAssembly::S_FUNCINDEX, Ctx&: OutContext),
685 Size: 4);
686 }
687 OutStreamer->popSection();
688 }
689}
690
691void WebAssemblyAsmPrinter::emitConstantPool() {
692 emitDecls(M: *MMI->getModule());
693 assert(MF->getConstantPool()->getConstants().empty() &&
694 "WebAssembly disables constant pools");
695}
696
697void WebAssemblyAsmPrinter::emitJumpTableInfo() {
698 // Nothing to do; jump tables are incorporated into the instruction stream.
699}
700
701void WebAssemblyAsmPrinter::emitFunctionBodyStart() {
702 const Function &F = MF->getFunction();
703 SmallVector<MVT, 1> ResultVTs;
704 SmallVector<MVT, 4> ParamVTs;
705 computeSignatureVTs(Ty: F.getFunctionType(), TargetFunc: &F, ContextFunc: F, TM, Params&: ParamVTs, Results&: ResultVTs);
706
707 auto Signature = signatureFromMVTs(Ctx&: OutContext, Results: ResultVTs, Params: ParamVTs);
708 auto *WasmSym = static_cast<MCSymbolWasm *>(CurrentFnSym);
709 WasmSym->setSignature(Signature);
710 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
711
712 getTargetStreamer()->emitFunctionType(Sym: WasmSym);
713
714 // Emit the function index.
715 if (MDNode *Idx = F.getMetadata(Kind: "wasm.index")) {
716 assert(Idx->getNumOperands() == 1);
717
718 getTargetStreamer()->emitIndIdx(Value: AsmPrinter::lowerConstant(
719 CV: cast<ConstantAsMetadata>(Val: Idx->getOperand(I: 0))->getValue()));
720 }
721
722 SmallVector<wasm::ValType, 16> Locals;
723 valTypesFromMVTs(In: MFI->getLocals(), Out&: Locals);
724 getTargetStreamer()->emitLocal(Types: Locals);
725
726 AsmPrinter::emitFunctionBodyStart();
727}
728
729void WebAssemblyAsmPrinter::emitInstruction(const MachineInstr *MI) {
730 LLVM_DEBUG(dbgs() << "EmitInstruction: " << *MI << '\n');
731 WebAssembly_MC::verifyInstructionPredicates(Opcode: MI->getOpcode(),
732 Features: Subtarget->getFeatureBits());
733
734 switch (MI->getOpcode()) {
735 case WebAssembly::ARGUMENT_i32:
736 case WebAssembly::ARGUMENT_i32_S:
737 case WebAssembly::ARGUMENT_i64:
738 case WebAssembly::ARGUMENT_i64_S:
739 case WebAssembly::ARGUMENT_f32:
740 case WebAssembly::ARGUMENT_f32_S:
741 case WebAssembly::ARGUMENT_f64:
742 case WebAssembly::ARGUMENT_f64_S:
743 case WebAssembly::ARGUMENT_v16i8:
744 case WebAssembly::ARGUMENT_v16i8_S:
745 case WebAssembly::ARGUMENT_v8i16:
746 case WebAssembly::ARGUMENT_v8i16_S:
747 case WebAssembly::ARGUMENT_v4i32:
748 case WebAssembly::ARGUMENT_v4i32_S:
749 case WebAssembly::ARGUMENT_v2i64:
750 case WebAssembly::ARGUMENT_v2i64_S:
751 case WebAssembly::ARGUMENT_v4f32:
752 case WebAssembly::ARGUMENT_v4f32_S:
753 case WebAssembly::ARGUMENT_v2f64:
754 case WebAssembly::ARGUMENT_v2f64_S:
755 case WebAssembly::ARGUMENT_v8f16:
756 case WebAssembly::ARGUMENT_v8f16_S:
757 case WebAssembly::ARGUMENT_externref:
758 case WebAssembly::ARGUMENT_externref_S:
759 case WebAssembly::ARGUMENT_funcref:
760 case WebAssembly::ARGUMENT_funcref_S:
761 case WebAssembly::ARGUMENT_exnref:
762 case WebAssembly::ARGUMENT_exnref_S:
763 // These represent values which are live into the function entry, so there's
764 // no instruction to emit.
765 break;
766 case WebAssembly::FALLTHROUGH_RETURN: {
767 // These instructions represent the implicit return at the end of a
768 // function body.
769 if (isVerbose()) {
770 OutStreamer->AddComment(T: "fallthrough-return");
771 OutStreamer->addBlankLine();
772 }
773 break;
774 }
775 case WebAssembly::COMPILER_FENCE:
776 // This is a compiler barrier that prevents instruction reordering during
777 // backend compilation, and should not be emitted.
778 break;
779 case WebAssembly::CATCH:
780 case WebAssembly::CATCH_S:
781 case WebAssembly::CATCH_REF:
782 case WebAssembly::CATCH_REF_S:
783 case WebAssembly::CATCH_ALL:
784 case WebAssembly::CATCH_ALL_S:
785 case WebAssembly::CATCH_ALL_REF:
786 case WebAssembly::CATCH_ALL_REF_S:
787 // These are pseudo instructions to represent catch clauses in try_table
788 // instruction to simulate block return values.
789 break;
790 default: {
791 WebAssemblyMCInstLower MCInstLowering(OutContext, *this);
792 MCInst TmpInst;
793 MCInstLowering.lower(MI, OutMI&: TmpInst);
794 EmitToStreamer(S&: *OutStreamer, Inst: TmpInst);
795 break;
796 }
797 }
798}
799
800bool WebAssemblyAsmPrinter::PrintAsmOperand(const MachineInstr *MI,
801 unsigned OpNo,
802 const char *ExtraCode,
803 raw_ostream &OS) {
804 // First try the generic code, which knows about modifiers like 'c' and 'n'.
805 if (!AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, OS))
806 return false;
807
808 if (!ExtraCode) {
809 const MachineOperand &MO = MI->getOperand(i: OpNo);
810 switch (MO.getType()) {
811 case MachineOperand::MO_Immediate:
812 OS << MO.getImm();
813 return false;
814 case MachineOperand::MO_Register:
815 // FIXME: only opcode that still contains registers, as required by
816 // MachineInstr::getDebugVariable().
817 assert(MI->getOpcode() == WebAssembly::INLINEASM);
818 OS << regToString(MO);
819 return false;
820 case MachineOperand::MO_GlobalAddress:
821 PrintSymbolOperand(MO, OS);
822 return false;
823 case MachineOperand::MO_ExternalSymbol:
824 GetExternalSymbolSymbol(Sym: MO.getSymbolName())->print(OS, MAI);
825 printOffset(Offset: MO.getOffset(), OS);
826 return false;
827 case MachineOperand::MO_MachineBasicBlock:
828 MO.getMBB()->getSymbol()->print(OS, MAI);
829 return false;
830 default:
831 break;
832 }
833 }
834
835 return true;
836}
837
838bool WebAssemblyAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
839 unsigned OpNo,
840 const char *ExtraCode,
841 raw_ostream &OS) {
842 // The current approach to inline asm is that "r" constraints are expressed
843 // as local indices, rather than values on the operand stack. This simplifies
844 // using "r" as it eliminates the need to push and pop the values in a
845 // particular order, however it also makes it impossible to have an "m"
846 // constraint. So we don't support it.
847
848 return AsmPrinter::PrintAsmMemoryOperand(MI, OpNo, ExtraCode, OS);
849}
850
851char WebAssemblyAsmPrinter::ID = 0;
852
853INITIALIZE_PASS(WebAssemblyAsmPrinter, "webassembly-asm-printer",
854 "WebAssembly Assembly Printer", false, false)
855
856// Force static initialization.
857extern "C" LLVM_ABI LLVM_EXTERNAL_VISIBILITY void
858LLVMInitializeWebAssemblyAsmPrinter() {
859 RegisterAsmPrinter<WebAssemblyAsmPrinter> X(getTheWebAssemblyTarget32());
860 RegisterAsmPrinter<WebAssemblyAsmPrinter> Y(getTheWebAssemblyTarget64());
861}
862
863PreservedAnalyses
864WebAssemblyAsmPrinterBeginPass::run(Module &M, ModuleAnalysisManager &MAM) {
865 WebAssemblyAsmPrinter &AsmPrinter = static_cast<WebAssemblyAsmPrinter &>(
866 MAM.getResult<AsmPrinterAnalysis>(IR&: M).getPrinter());
867 setupModuleAsmPrinter(M, MAM, AsmPrinter);
868 AsmPrinter.doInitialization(M);
869 return PreservedAnalyses::all();
870}
871
872PreservedAnalyses
873WebAssemblyAsmPrinterPass::run(MachineFunction &MF,
874 MachineFunctionAnalysisManager &MFAM) {
875 WebAssemblyAsmPrinter &AsmPrinter = static_cast<WebAssemblyAsmPrinter &>(
876 MFAM.getResult<ModuleAnalysisManagerMachineFunctionProxy>(IR&: MF)
877 .getCachedResult<AsmPrinterAnalysis>(IR&: *MF.getFunction().getParent())
878 ->getPrinter());
879 setupMachineFunctionAsmPrinter(MFAM, MF, AsmPrinter);
880 AsmPrinter.runOnMachineFunction(MF);
881 return PreservedAnalyses::all();
882}
883
884PreservedAnalyses
885WebAssemblyAsmPrinterEndPass::run(Module &M, ModuleAnalysisManager &MAM) {
886 WebAssemblyAsmPrinter &AsmPrinter = static_cast<WebAssemblyAsmPrinter &>(
887 MAM.getResult<AsmPrinterAnalysis>(IR&: M).getPrinter());
888 setupModuleAsmPrinter(M, MAM, AsmPrinter);
889 AsmPrinter.doFinalization(M);
890 return PreservedAnalyses::all();
891}
892