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 "WebAssemblyMachineFunctionInfo.h" 19 #include "llvm/ADT/SmallSet.h" 20 #include "llvm/ADT/StringExtras.h" 21 #include "llvm/CodeGen/TargetRegisterInfo.h" 22 #include "llvm/MC/MCExpr.h" 23 #include "llvm/MC/MCInst.h" 24 #include "llvm/MC/MCInstrInfo.h" 25 #include "llvm/MC/MCSubtargetInfo.h" 26 #include "llvm/MC/MCSymbol.h" 27 #include "llvm/Support/ErrorHandling.h" 28 #include "llvm/Support/FormattedStream.h" 29 using namespace llvm; 30 31 #define DEBUG_TYPE "asm-printer" 32 33 #include "WebAssemblyGenAsmWriter.inc" 34 35 WebAssemblyInstPrinter::WebAssemblyInstPrinter(const MCAsmInfo &MAI, 36 const MCInstrInfo &MII, 37 const MCRegisterInfo &MRI) 38 : MCInstPrinter(MAI, MII, MRI) {} 39 40 void WebAssemblyInstPrinter::printRegName(raw_ostream &OS, 41 MCRegister Reg) const { 42 assert(Reg.id() != WebAssemblyFunctionInfo::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 if (CommentStream) { 113 // Observe any effects on the control flow stack, for use in annotating 114 // control flow label references. 115 unsigned Opc = MI->getOpcode(); 116 switch (Opc) { 117 default: 118 break; 119 120 case WebAssembly::LOOP: 121 case WebAssembly::LOOP_S: 122 printAnnotation(OS, "label" + utostr(ControlFlowCounter) + ':'); 123 ControlFlowStack.push_back(std::make_pair(ControlFlowCounter++, true)); 124 return; 125 126 case WebAssembly::BLOCK: 127 case WebAssembly::BLOCK_S: 128 ControlFlowStack.push_back(std::make_pair(ControlFlowCounter++, false)); 129 return; 130 131 case WebAssembly::TRY: 132 case WebAssembly::TRY_S: 133 ControlFlowStack.push_back(std::make_pair(ControlFlowCounter, false)); 134 TryStack.push_back(ControlFlowCounter++); 135 EHInstStack.push_back(TRY); 136 return; 137 138 case WebAssembly::END_LOOP: 139 case WebAssembly::END_LOOP_S: 140 if (ControlFlowStack.empty()) { 141 printAnnotation(OS, "End marker mismatch!"); 142 } else { 143 ControlFlowStack.pop_back(); 144 } 145 return; 146 147 case WebAssembly::END_BLOCK: 148 case WebAssembly::END_BLOCK_S: 149 if (ControlFlowStack.empty()) { 150 printAnnotation(OS, "End marker mismatch!"); 151 } else { 152 printAnnotation( 153 OS, "label" + utostr(ControlFlowStack.pop_back_val().first) + ':'); 154 } 155 return; 156 157 case WebAssembly::END_TRY: 158 case WebAssembly::END_TRY_S: 159 if (ControlFlowStack.empty() || EHInstStack.empty()) { 160 printAnnotation(OS, "End marker mismatch!"); 161 } else { 162 printAnnotation( 163 OS, "label" + utostr(ControlFlowStack.pop_back_val().first) + ':'); 164 EHInstStack.pop_back(); 165 } 166 return; 167 168 case WebAssembly::CATCH: 169 case WebAssembly::CATCH_S: 170 case WebAssembly::CATCH_ALL: 171 case WebAssembly::CATCH_ALL_S: 172 // There can be multiple catch instructions for one try instruction, so 173 // we print a label only for the first 'catch' label. 174 if (EHInstStack.empty()) { 175 printAnnotation(OS, "try-catch mismatch!"); 176 } else if (EHInstStack.back() == CATCH_ALL) { 177 printAnnotation(OS, "catch/catch_all cannot occur after catch_all"); 178 } else if (EHInstStack.back() == TRY) { 179 if (TryStack.empty()) { 180 printAnnotation(OS, "try-catch mismatch!"); 181 } else { 182 printAnnotation(OS, "catch" + utostr(TryStack.pop_back_val()) + ':'); 183 } 184 EHInstStack.pop_back(); 185 if (Opc == WebAssembly::CATCH || Opc == WebAssembly::CATCH_S) { 186 EHInstStack.push_back(CATCH); 187 } else { 188 EHInstStack.push_back(CATCH_ALL); 189 } 190 } 191 return; 192 193 case WebAssembly::RETHROW: 194 case WebAssembly::RETHROW_S: 195 // 'rethrow' rethrows to the nearest enclosing catch scope, if any. If 196 // there's no enclosing catch scope, it throws up to the caller. 197 if (TryStack.empty()) { 198 printAnnotation(OS, "to caller"); 199 } else { 200 printAnnotation(OS, "down to catch" + utostr(TryStack.back())); 201 } 202 return; 203 204 case WebAssembly::DELEGATE: 205 case WebAssembly::DELEGATE_S: 206 if (ControlFlowStack.empty() || TryStack.empty() || EHInstStack.empty()) { 207 printAnnotation(OS, "try-delegate mismatch!"); 208 } else { 209 // 'delegate' is 210 // 1. A marker for the end of block label 211 // 2. A destination for throwing instructions 212 // 3. An instruction that itself rethrows to another 'catch' 213 assert(ControlFlowStack.back().first == TryStack.back()); 214 std::string Label = "label/catch" + 215 utostr(ControlFlowStack.pop_back_val().first) + 216 ": "; 217 TryStack.pop_back(); 218 EHInstStack.pop_back(); 219 uint64_t Depth = MI->getOperand(0).getImm(); 220 if (Depth >= ControlFlowStack.size()) { 221 Label += "to caller"; 222 } else { 223 const auto &Pair = ControlFlowStack.rbegin()[Depth]; 224 if (Pair.second) 225 printAnnotation(OS, "delegate cannot target a loop"); 226 else 227 Label += "down to catch" + utostr(Pair.first); 228 } 229 printAnnotation(OS, Label); 230 } 231 return; 232 } 233 234 // Annotate any control flow label references. 235 236 unsigned NumFixedOperands = Desc.NumOperands; 237 SmallSet<uint64_t, 8> Printed; 238 for (unsigned I = 0, E = MI->getNumOperands(); I < E; ++I) { 239 // See if this operand denotes a basic block target. 240 if (I < NumFixedOperands) { 241 // A non-variable_ops operand, check its type. 242 if (Desc.operands()[I].OperandType != WebAssembly::OPERAND_BASIC_BLOCK) 243 continue; 244 } else { 245 // A variable_ops operand, which currently can be immediates (used in 246 // br_table) which are basic block targets, or for call instructions 247 // when using -wasm-keep-registers (in which case they are registers, 248 // and should not be processed). 249 if (!MI->getOperand(I).isImm()) 250 continue; 251 } 252 uint64_t Depth = MI->getOperand(I).getImm(); 253 if (!Printed.insert(Depth).second) 254 continue; 255 if (Depth >= ControlFlowStack.size()) { 256 printAnnotation(OS, "Invalid depth argument!"); 257 } else { 258 const auto &Pair = ControlFlowStack.rbegin()[Depth]; 259 printAnnotation(OS, utostr(Depth) + ": " + 260 (Pair.second ? "up" : "down") + " to label" + 261 utostr(Pair.first)); 262 } 263 } 264 } 265 } 266 267 static std::string toString(const APFloat &FP) { 268 // Print NaNs with custom payloads specially. 269 if (FP.isNaN() && !FP.bitwiseIsEqual(APFloat::getQNaN(FP.getSemantics())) && 270 !FP.bitwiseIsEqual( 271 APFloat::getQNaN(FP.getSemantics(), /*Negative=*/true))) { 272 APInt AI = FP.bitcastToAPInt(); 273 return std::string(AI.isNegative() ? "-" : "") + "nan:0x" + 274 utohexstr(AI.getZExtValue() & 275 (AI.getBitWidth() == 32 ? INT64_C(0x007fffff) 276 : INT64_C(0x000fffffffffffff)), 277 /*LowerCase=*/true); 278 } 279 280 // Use C99's hexadecimal floating-point representation. 281 static const size_t BufBytes = 128; 282 char Buf[BufBytes]; 283 auto Written = FP.convertToHexString( 284 Buf, /*HexDigits=*/0, /*UpperCase=*/false, APFloat::rmNearestTiesToEven); 285 (void)Written; 286 assert(Written != 0); 287 assert(Written < BufBytes); 288 return Buf; 289 } 290 291 void WebAssemblyInstPrinter::printOperand(const MCInst *MI, unsigned OpNo, 292 raw_ostream &O, bool IsVariadicDef) { 293 const MCOperand &Op = MI->getOperand(OpNo); 294 if (Op.isReg()) { 295 const MCInstrDesc &Desc = MII.get(MI->getOpcode()); 296 unsigned WAReg = Op.getReg(); 297 if (int(WAReg) >= 0) 298 printRegName(O, WAReg); 299 else if (OpNo >= Desc.getNumDefs() && !IsVariadicDef) 300 O << "$pop" << WebAssemblyFunctionInfo::getWARegStackId(WAReg); 301 else if (WAReg != WebAssemblyFunctionInfo::UnusedReg) 302 O << "$push" << WebAssemblyFunctionInfo::getWARegStackId(WAReg); 303 else 304 O << "$drop"; 305 // Add a '=' suffix if this is a def. 306 if (OpNo < MII.get(MI->getOpcode()).getNumDefs() || IsVariadicDef) 307 O << '='; 308 } else if (Op.isImm()) { 309 O << Op.getImm(); 310 } else if (Op.isSFPImm()) { 311 O << ::toString(APFloat(APFloat::IEEEsingle(), APInt(32, Op.getSFPImm()))); 312 } else if (Op.isDFPImm()) { 313 O << ::toString(APFloat(APFloat::IEEEdouble(), APInt(64, Op.getDFPImm()))); 314 } else { 315 assert(Op.isExpr() && "unknown operand kind in printOperand"); 316 // call_indirect instructions have a TYPEINDEX operand that we print 317 // as a signature here, such that the assembler can recover this 318 // information. 319 auto SRE = static_cast<const MCSymbolRefExpr *>(Op.getExpr()); 320 if (SRE->getKind() == MCSymbolRefExpr::VK_WASM_TYPEINDEX) { 321 auto &Sym = static_cast<const MCSymbolWasm &>(SRE->getSymbol()); 322 O << WebAssembly::signatureToString(Sym.getSignature()); 323 } else { 324 Op.getExpr()->print(O, &MAI); 325 } 326 } 327 } 328 329 void WebAssemblyInstPrinter::printBrList(const MCInst *MI, unsigned OpNo, 330 raw_ostream &O) { 331 O << "{"; 332 for (unsigned I = OpNo, E = MI->getNumOperands(); I != E; ++I) { 333 if (I != OpNo) 334 O << ", "; 335 O << MI->getOperand(I).getImm(); 336 } 337 O << "}"; 338 } 339 340 void WebAssemblyInstPrinter::printWebAssemblyP2AlignOperand(const MCInst *MI, 341 unsigned OpNo, 342 raw_ostream &O) { 343 int64_t Imm = MI->getOperand(OpNo).getImm(); 344 if (Imm == WebAssembly::GetDefaultP2Align(MI->getOpcode())) 345 return; 346 O << ":p2align=" << Imm; 347 } 348 349 void WebAssemblyInstPrinter::printWebAssemblySignatureOperand(const MCInst *MI, 350 unsigned OpNo, 351 raw_ostream &O) { 352 const MCOperand &Op = MI->getOperand(OpNo); 353 if (Op.isImm()) { 354 auto Imm = static_cast<unsigned>(Op.getImm()); 355 if (Imm != wasm::WASM_TYPE_NORESULT) 356 O << WebAssembly::anyTypeToString(Imm); 357 } else { 358 auto Expr = cast<MCSymbolRefExpr>(Op.getExpr()); 359 auto *Sym = cast<MCSymbolWasm>(&Expr->getSymbol()); 360 if (Sym->getSignature()) { 361 O << WebAssembly::signatureToString(Sym->getSignature()); 362 } else { 363 // Disassembler does not currently produce a signature 364 O << "unknown_type"; 365 } 366 } 367 } 368