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