1 //=- WebAssemblyInstPrinter.cpp - WebAssembly assembly instruction printing -=// 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 /// Print MCInst instructions to wasm format. 11 /// 12 //===----------------------------------------------------------------------===// 13 14 #include "MCTargetDesc/WebAssemblyInstPrinter.h" 15 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h" 16 #include "MCTargetDesc/WebAssemblyMCTypeUtilities.h" 17 #include "WebAssembly.h" 18 #include "llvm/ADT/APFloat.h" 19 #include "llvm/ADT/SmallSet.h" 20 #include "llvm/ADT/StringExtras.h" 21 #include "llvm/MC/MCExpr.h" 22 #include "llvm/MC/MCInst.h" 23 #include "llvm/MC/MCInstrInfo.h" 24 #include "llvm/MC/MCSubtargetInfo.h" 25 #include "llvm/MC/MCSymbol.h" 26 #include "llvm/MC/MCSymbolWasm.h" 27 #include "llvm/Support/Casting.h" 28 #include "llvm/Support/ErrorHandling.h" 29 #include "llvm/Support/FormattedStream.h" 30 using namespace llvm; 31 32 #define DEBUG_TYPE "asm-printer" 33 34 #include "WebAssemblyGenAsmWriter.inc" 35 36 WebAssemblyInstPrinter::WebAssemblyInstPrinter(const MCAsmInfo &MAI, 37 const MCInstrInfo &MII, 38 const MCRegisterInfo &MRI) 39 : MCInstPrinter(MAI, MII, MRI) {} 40 41 void WebAssemblyInstPrinter::printRegName(raw_ostream &OS, MCRegister Reg) { 42 assert(Reg.id() != WebAssembly::UnusedReg); 43 // Note that there's an implicit local.get/local.set here! 44 OS << "$" << Reg.id(); 45 } 46 47 void WebAssemblyInstPrinter::printInst(const MCInst *MI, uint64_t Address, 48 StringRef Annot, 49 const MCSubtargetInfo &STI, 50 raw_ostream &OS) { 51 switch (MI->getOpcode()) { 52 case WebAssembly::CALL_INDIRECT_S: 53 case WebAssembly::RET_CALL_INDIRECT_S: { 54 // A special case for call_indirect (and ret_call_indirect), if the table 55 // operand is a symbol: the order of the type and table operands is inverted 56 // in the text format relative to the binary format. Otherwise if table the 57 // operand isn't a symbol, then we have an MVP compilation unit, and the 58 // table shouldn't appear in the output. 59 OS << "\t"; 60 OS << getMnemonic(MI).first; 61 OS << " "; 62 63 assert(MI->getNumOperands() == 2); 64 const unsigned TypeOperand = 0; 65 const unsigned TableOperand = 1; 66 if (MI->getOperand(TableOperand).isExpr()) { 67 printOperand(MI, TableOperand, OS); 68 OS << ", "; 69 } else { 70 assert(MI->getOperand(TableOperand).getImm() == 0); 71 } 72 printOperand(MI, TypeOperand, OS); 73 break; 74 } 75 default: 76 // Print the instruction (this uses the AsmStrings from the .td files). 77 printInstruction(MI, Address, OS); 78 break; 79 } 80 81 // Print any additional variadic operands. 82 const MCInstrDesc &Desc = MII.get(MI->getOpcode()); 83 if (Desc.isVariadic()) { 84 if ((Desc.getNumOperands() == 0 && MI->getNumOperands() > 0) || 85 Desc.variadicOpsAreDefs()) 86 OS << "\t"; 87 unsigned Start = Desc.getNumOperands(); 88 unsigned NumVariadicDefs = 0; 89 if (Desc.variadicOpsAreDefs()) { 90 // The number of variadic defs is encoded in an immediate by MCInstLower 91 NumVariadicDefs = MI->getOperand(0).getImm(); 92 Start = 1; 93 } 94 bool NeedsComma = Desc.getNumOperands() > 0 && !Desc.variadicOpsAreDefs(); 95 for (auto I = Start, E = MI->getNumOperands(); I < E; ++I) { 96 if (MI->getOpcode() == WebAssembly::CALL_INDIRECT && 97 I - Start == NumVariadicDefs) { 98 // Skip type and table arguments when printing for tests. 99 ++I; 100 continue; 101 } 102 if (NeedsComma) 103 OS << ", "; 104 printOperand(MI, I, OS, I - Start < NumVariadicDefs); 105 NeedsComma = true; 106 } 107 } 108 109 // Print any added annotation. 110 printAnnotation(OS, Annot); 111 112 auto PrintBranchAnnotation = [&](const MCOperand &Op, 113 SmallSet<uint64_t, 8> &Printed) { 114 uint64_t Depth = Op.getImm(); 115 if (!Printed.insert(Depth).second) 116 return; 117 if (Depth >= ControlFlowStack.size()) { 118 printAnnotation(OS, "Invalid depth argument!"); 119 } else { 120 const auto &Pair = ControlFlowStack.rbegin()[Depth]; 121 printAnnotation(OS, utostr(Depth) + ": " + (Pair.second ? "up" : "down") + 122 " to label" + utostr(Pair.first)); 123 } 124 }; 125 126 if (CommentStream) { 127 // Observe any effects on the control flow stack, for use in annotating 128 // control flow label references. 129 unsigned Opc = MI->getOpcode(); 130 switch (Opc) { 131 default: 132 break; 133 134 case WebAssembly::LOOP: 135 case WebAssembly::LOOP_S: 136 printAnnotation(OS, "label" + utostr(ControlFlowCounter) + ':'); 137 ControlFlowStack.push_back(std::make_pair(ControlFlowCounter++, true)); 138 return; 139 140 case WebAssembly::BLOCK: 141 case WebAssembly::BLOCK_S: 142 ControlFlowStack.push_back(std::make_pair(ControlFlowCounter++, false)); 143 return; 144 145 case WebAssembly::TRY: 146 case WebAssembly::TRY_S: 147 ControlFlowStack.push_back(std::make_pair(ControlFlowCounter, false)); 148 TryStack.push_back(ControlFlowCounter++); 149 EHInstStack.push_back(TRY); 150 return; 151 152 case WebAssembly::TRY_TABLE: 153 case WebAssembly::TRY_TABLE_S: { 154 SmallSet<uint64_t, 8> Printed; 155 unsigned OpIdx = 1; 156 const MCOperand &Op = MI->getOperand(OpIdx++); 157 unsigned NumCatches = Op.getImm(); 158 for (unsigned I = 0; I < NumCatches; I++) { 159 int64_t CatchOpcode = MI->getOperand(OpIdx++).getImm(); 160 if (CatchOpcode == wasm::WASM_OPCODE_CATCH || 161 CatchOpcode == wasm::WASM_OPCODE_CATCH_REF) 162 OpIdx++; // Skip tag 163 PrintBranchAnnotation(MI->getOperand(OpIdx++), Printed); 164 } 165 ControlFlowStack.push_back(std::make_pair(ControlFlowCounter++, false)); 166 return; 167 } 168 169 case WebAssembly::END_LOOP: 170 case WebAssembly::END_LOOP_S: 171 if (ControlFlowStack.empty()) { 172 printAnnotation(OS, "End marker mismatch!"); 173 } else { 174 ControlFlowStack.pop_back(); 175 } 176 return; 177 178 case WebAssembly::END_BLOCK: 179 case WebAssembly::END_BLOCK_S: 180 case WebAssembly::END_TRY_TABLE: 181 case WebAssembly::END_TRY_TABLE_S: 182 if (ControlFlowStack.empty()) { 183 printAnnotation(OS, "End marker mismatch!"); 184 } else { 185 printAnnotation( 186 OS, "label" + utostr(ControlFlowStack.pop_back_val().first) + ':'); 187 } 188 return; 189 190 case WebAssembly::END_TRY: 191 case WebAssembly::END_TRY_S: 192 if (ControlFlowStack.empty() || EHInstStack.empty()) { 193 printAnnotation(OS, "End marker mismatch!"); 194 } else { 195 printAnnotation( 196 OS, "label" + utostr(ControlFlowStack.pop_back_val().first) + ':'); 197 EHInstStack.pop_back(); 198 } 199 return; 200 201 case WebAssembly::CATCH_LEGACY: 202 case WebAssembly::CATCH_LEGACY_S: 203 case WebAssembly::CATCH_ALL_LEGACY: 204 case WebAssembly::CATCH_ALL_LEGACY_S: 205 // There can be multiple catch instructions for one try instruction, so 206 // we print a label only for the first 'catch' label. 207 if (EHInstStack.empty()) { 208 printAnnotation(OS, "try-catch mismatch!"); 209 } else if (EHInstStack.back() == CATCH_ALL_LEGACY) { 210 printAnnotation(OS, "catch/catch_all cannot occur after catch_all"); 211 } else if (EHInstStack.back() == TRY) { 212 if (TryStack.empty()) { 213 printAnnotation(OS, "try-catch mismatch!"); 214 } else { 215 printAnnotation(OS, "catch" + utostr(TryStack.pop_back_val()) + ':'); 216 } 217 EHInstStack.pop_back(); 218 if (Opc == WebAssembly::CATCH_LEGACY || 219 Opc == WebAssembly::CATCH_LEGACY_S) { 220 EHInstStack.push_back(CATCH_LEGACY); 221 } else { 222 EHInstStack.push_back(CATCH_ALL_LEGACY); 223 } 224 } 225 return; 226 227 case WebAssembly::RETHROW: 228 case WebAssembly::RETHROW_S: 229 // 'rethrow' rethrows to the nearest enclosing catch scope, if any. If 230 // there's no enclosing catch scope, it throws up to the caller. 231 if (TryStack.empty()) { 232 printAnnotation(OS, "to caller"); 233 } else { 234 printAnnotation(OS, "down to catch" + utostr(TryStack.back())); 235 } 236 return; 237 238 case WebAssembly::DELEGATE: 239 case WebAssembly::DELEGATE_S: 240 if (ControlFlowStack.empty() || TryStack.empty() || EHInstStack.empty()) { 241 printAnnotation(OS, "try-delegate mismatch!"); 242 } else { 243 // 'delegate' is 244 // 1. A marker for the end of block label 245 // 2. A destination for throwing instructions 246 // 3. An instruction that itself rethrows to another 'catch' 247 assert(ControlFlowStack.back().first == TryStack.back()); 248 std::string Label = "label/catch" + 249 utostr(ControlFlowStack.pop_back_val().first) + 250 ": "; 251 TryStack.pop_back(); 252 EHInstStack.pop_back(); 253 uint64_t Depth = MI->getOperand(0).getImm(); 254 if (Depth >= ControlFlowStack.size()) { 255 Label += "to caller"; 256 } else { 257 const auto &Pair = ControlFlowStack.rbegin()[Depth]; 258 if (Pair.second) 259 printAnnotation(OS, "delegate cannot target a loop"); 260 else 261 Label += "down to catch" + utostr(Pair.first); 262 } 263 printAnnotation(OS, Label); 264 } 265 return; 266 } 267 268 // Annotate any control flow label references. 269 270 unsigned NumFixedOperands = Desc.NumOperands; 271 SmallSet<uint64_t, 8> Printed; 272 for (unsigned I = 0, E = MI->getNumOperands(); I < E; ++I) { 273 // See if this operand denotes a basic block target. 274 if (I < NumFixedOperands) { 275 // A non-variable_ops operand, check its type. 276 if (Desc.operands()[I].OperandType != WebAssembly::OPERAND_BASIC_BLOCK) 277 continue; 278 } else { 279 // A variable_ops operand, which currently can be immediates (used in 280 // br_table) which are basic block targets, or for call instructions 281 // when using -wasm-keep-registers (in which case they are registers, 282 // and should not be processed). 283 if (!MI->getOperand(I).isImm()) 284 continue; 285 } 286 PrintBranchAnnotation(MI->getOperand(I), Printed); 287 } 288 } 289 } 290 291 static std::string toString(const APFloat &FP) { 292 // Print NaNs with custom payloads specially. 293 if (FP.isNaN() && !FP.bitwiseIsEqual(APFloat::getQNaN(FP.getSemantics())) && 294 !FP.bitwiseIsEqual( 295 APFloat::getQNaN(FP.getSemantics(), /*Negative=*/true))) { 296 APInt AI = FP.bitcastToAPInt(); 297 return std::string(AI.isNegative() ? "-" : "") + "nan:0x" + 298 utohexstr(AI.getZExtValue() & 299 (AI.getBitWidth() == 32 ? INT64_C(0x007fffff) 300 : INT64_C(0x000fffffffffffff)), 301 /*LowerCase=*/true); 302 } 303 304 // Use C99's hexadecimal floating-point representation. 305 static const size_t BufBytes = 128; 306 char Buf[BufBytes]; 307 auto Written = FP.convertToHexString( 308 Buf, /*HexDigits=*/0, /*UpperCase=*/false, APFloat::rmNearestTiesToEven); 309 (void)Written; 310 assert(Written != 0); 311 assert(Written < BufBytes); 312 return Buf; 313 } 314 315 void WebAssemblyInstPrinter::printOperand(const MCInst *MI, unsigned OpNo, 316 raw_ostream &O, bool IsVariadicDef) { 317 const MCOperand &Op = MI->getOperand(OpNo); 318 if (Op.isReg()) { 319 const MCInstrDesc &Desc = MII.get(MI->getOpcode()); 320 unsigned WAReg = Op.getReg(); 321 if (int(WAReg) >= 0) 322 printRegName(O, WAReg); 323 else if (OpNo >= Desc.getNumDefs() && !IsVariadicDef) 324 O << "$pop" << WebAssembly::getWARegStackId(WAReg); 325 else if (WAReg != WebAssembly::UnusedReg) 326 O << "$push" << WebAssembly::getWARegStackId(WAReg); 327 else 328 O << "$drop"; 329 // Add a '=' suffix if this is a def. 330 if (OpNo < MII.get(MI->getOpcode()).getNumDefs() || IsVariadicDef) 331 O << '='; 332 } else if (Op.isImm()) { 333 O << Op.getImm(); 334 } else if (Op.isSFPImm()) { 335 O << ::toString(APFloat(APFloat::IEEEsingle(), APInt(32, Op.getSFPImm()))); 336 } else if (Op.isDFPImm()) { 337 O << ::toString(APFloat(APFloat::IEEEdouble(), APInt(64, Op.getDFPImm()))); 338 } else { 339 assert(Op.isExpr() && "unknown operand kind in printOperand"); 340 // call_indirect instructions have a TYPEINDEX operand that we print 341 // as a signature here, such that the assembler can recover this 342 // information. 343 auto SRE = static_cast<const MCSymbolRefExpr *>(Op.getExpr()); 344 if (SRE->getKind() == MCSymbolRefExpr::VK_WASM_TYPEINDEX) { 345 auto &Sym = static_cast<const MCSymbolWasm &>(SRE->getSymbol()); 346 O << WebAssembly::signatureToString(Sym.getSignature()); 347 } else { 348 Op.getExpr()->print(O, &MAI); 349 } 350 } 351 } 352 353 void WebAssemblyInstPrinter::printBrList(const MCInst *MI, unsigned OpNo, 354 raw_ostream &O) { 355 O << "{"; 356 for (unsigned I = OpNo, E = MI->getNumOperands(); I != E; ++I) { 357 if (I != OpNo) 358 O << ", "; 359 O << MI->getOperand(I).getImm(); 360 } 361 O << "}"; 362 } 363 364 void WebAssemblyInstPrinter::printWebAssemblyP2AlignOperand(const MCInst *MI, 365 unsigned OpNo, 366 raw_ostream &O) { 367 int64_t Imm = MI->getOperand(OpNo).getImm(); 368 if (Imm == WebAssembly::GetDefaultP2Align(MI->getOpcode())) 369 return; 370 O << ":p2align=" << Imm; 371 } 372 373 void WebAssemblyInstPrinter::printWebAssemblySignatureOperand(const MCInst *MI, 374 unsigned OpNo, 375 raw_ostream &O) { 376 const MCOperand &Op = MI->getOperand(OpNo); 377 if (Op.isImm()) { 378 auto Imm = static_cast<unsigned>(Op.getImm()); 379 if (Imm != wasm::WASM_TYPE_NORESULT) 380 O << WebAssembly::anyTypeToString(Imm); 381 } else { 382 auto Expr = cast<MCSymbolRefExpr>(Op.getExpr()); 383 auto *Sym = cast<MCSymbolWasm>(&Expr->getSymbol()); 384 if (Sym->getSignature()) { 385 O << WebAssembly::signatureToString(Sym->getSignature()); 386 } else { 387 // Disassembler does not currently produce a signature 388 O << "unknown_type"; 389 } 390 } 391 } 392 393 void WebAssemblyInstPrinter::printCatchList(const MCInst *MI, unsigned OpNo, 394 raw_ostream &O) { 395 unsigned OpIdx = OpNo; 396 const MCOperand &Op = MI->getOperand(OpIdx++); 397 unsigned NumCatches = Op.getImm(); 398 399 auto PrintTagOp = [&](const MCOperand &Op) { 400 const MCSymbolRefExpr *TagExpr = nullptr; 401 const MCSymbolWasm *TagSym = nullptr; 402 if (Op.isExpr()) { 403 TagExpr = cast<MCSymbolRefExpr>(Op.getExpr()); 404 TagSym = cast<MCSymbolWasm>(&TagExpr->getSymbol()); 405 O << TagSym->getName() << " "; 406 } else { 407 // When instructions are parsed from the disassembler, we have an 408 // immediate tag index and not a tag expr 409 O << Op.getImm() << " "; 410 } 411 }; 412 413 for (unsigned I = 0; I < NumCatches; I++) { 414 const MCOperand &Op = MI->getOperand(OpIdx++); 415 O << "("; 416 switch (Op.getImm()) { 417 case wasm::WASM_OPCODE_CATCH: 418 O << "catch "; 419 PrintTagOp(MI->getOperand(OpIdx++)); 420 break; 421 case wasm::WASM_OPCODE_CATCH_REF: 422 O << "catch_ref "; 423 PrintTagOp(MI->getOperand(OpIdx++)); 424 break; 425 case wasm::WASM_OPCODE_CATCH_ALL: 426 O << "catch_all "; 427 break; 428 case wasm::WASM_OPCODE_CATCH_ALL_REF: 429 O << "catch_all_ref "; 430 break; 431 } 432 O << MI->getOperand(OpIdx++).getImm(); // destination 433 O << ")"; 434 if (I < NumCatches - 1) 435 O << " "; 436 } 437 } 438