1 // WebAssemblyMCInstLower.cpp - Convert WebAssembly MachineInstr to an MCInst // 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 code to lower WebAssembly MachineInstrs to their 11 /// corresponding MCInst records. 12 /// 13 //===----------------------------------------------------------------------===// 14 15 #include "WebAssemblyMCInstLower.h" 16 #include "TargetInfo/WebAssemblyTargetInfo.h" 17 #include "Utils/WebAssemblyTypeUtilities.h" 18 #include "Utils/WebAssemblyUtilities.h" 19 #include "WebAssemblyAsmPrinter.h" 20 #include "WebAssemblyISelLowering.h" 21 #include "WebAssemblyMachineFunctionInfo.h" 22 #include "llvm/CodeGen/AsmPrinter.h" 23 #include "llvm/CodeGen/MachineFunction.h" 24 #include "llvm/IR/Constants.h" 25 #include "llvm/MC/MCAsmInfo.h" 26 #include "llvm/MC/MCContext.h" 27 #include "llvm/MC/MCExpr.h" 28 #include "llvm/MC/MCInst.h" 29 #include "llvm/MC/MCSymbolWasm.h" 30 #include "llvm/Support/ErrorHandling.h" 31 #include "llvm/Support/raw_ostream.h" 32 33 using namespace llvm; 34 35 // This disables the removal of registers when lowering into MC, as required 36 // by some current tests. 37 cl::opt<bool> 38 WasmKeepRegisters("wasm-keep-registers", cl::Hidden, 39 cl::desc("WebAssembly: output stack registers in" 40 " instruction output for test purposes only."), 41 cl::init(false)); 42 43 static void removeRegisterOperands(const MachineInstr *MI, MCInst &OutMI); 44 45 MCSymbol * 46 WebAssemblyMCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const { 47 const GlobalValue *Global = MO.getGlobal(); 48 if (!isa<Function>(Global)) { 49 auto *WasmSym = cast<MCSymbolWasm>(Printer.getSymbol(Global)); 50 // If the symbol doesn't have an explicit WasmSymbolType yet and the 51 // GlobalValue is actually a WebAssembly global, then ensure the symbol is a 52 // WASM_SYMBOL_TYPE_GLOBAL. 53 if (WebAssembly::isWasmVarAddressSpace(Global->getAddressSpace()) && 54 !WasmSym->getType()) { 55 const MachineFunction &MF = *MO.getParent()->getParent()->getParent(); 56 const TargetMachine &TM = MF.getTarget(); 57 const Function &CurrentFunc = MF.getFunction(); 58 Type *GlobalVT = Global->getValueType(); 59 SmallVector<MVT, 1> VTs; 60 computeLegalValueVTs(CurrentFunc, TM, GlobalVT, VTs); 61 62 WebAssembly::wasmSymbolSetType(WasmSym, GlobalVT, VTs); 63 } 64 return WasmSym; 65 } 66 67 const auto *FuncTy = cast<FunctionType>(Global->getValueType()); 68 const MachineFunction &MF = *MO.getParent()->getParent()->getParent(); 69 const TargetMachine &TM = MF.getTarget(); 70 const Function &CurrentFunc = MF.getFunction(); 71 72 SmallVector<MVT, 1> ResultMVTs; 73 SmallVector<MVT, 4> ParamMVTs; 74 const auto *const F = dyn_cast<Function>(Global); 75 computeSignatureVTs(FuncTy, F, CurrentFunc, TM, ParamMVTs, ResultMVTs); 76 auto Signature = signatureFromMVTs(ResultMVTs, ParamMVTs); 77 78 bool InvokeDetected = false; 79 auto *WasmSym = Printer.getMCSymbolForFunction( 80 F, WebAssembly::WasmEnableEmEH || WebAssembly::WasmEnableEmSjLj, 81 Signature.get(), InvokeDetected); 82 WasmSym->setSignature(Signature.get()); 83 Printer.addSignature(std::move(Signature)); 84 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION); 85 return WasmSym; 86 } 87 88 MCSymbol *WebAssemblyMCInstLower::GetExternalSymbolSymbol( 89 const MachineOperand &MO) const { 90 return Printer.getOrCreateWasmSymbol(MO.getSymbolName()); 91 } 92 93 MCOperand WebAssemblyMCInstLower::lowerSymbolOperand(const MachineOperand &MO, 94 MCSymbol *Sym) const { 95 MCSymbolRefExpr::VariantKind Kind = MCSymbolRefExpr::VK_None; 96 unsigned TargetFlags = MO.getTargetFlags(); 97 98 switch (TargetFlags) { 99 case WebAssemblyII::MO_NO_FLAG: 100 break; 101 case WebAssemblyII::MO_GOT_TLS: 102 Kind = MCSymbolRefExpr::VK_WASM_GOT_TLS; 103 break; 104 case WebAssemblyII::MO_GOT: 105 Kind = MCSymbolRefExpr::VK_GOT; 106 break; 107 case WebAssemblyII::MO_MEMORY_BASE_REL: 108 Kind = MCSymbolRefExpr::VK_WASM_MBREL; 109 break; 110 case WebAssemblyII::MO_TLS_BASE_REL: 111 Kind = MCSymbolRefExpr::VK_WASM_TLSREL; 112 break; 113 case WebAssemblyII::MO_TABLE_BASE_REL: 114 Kind = MCSymbolRefExpr::VK_WASM_TBREL; 115 break; 116 default: 117 llvm_unreachable("Unknown target flag on GV operand"); 118 } 119 120 const MCExpr *Expr = MCSymbolRefExpr::create(Sym, Kind, Ctx); 121 122 if (MO.getOffset() != 0) { 123 const auto *WasmSym = cast<MCSymbolWasm>(Sym); 124 if (TargetFlags == WebAssemblyII::MO_GOT) 125 report_fatal_error("GOT symbol references do not support offsets"); 126 if (WasmSym->isFunction()) 127 report_fatal_error("Function addresses with offsets not supported"); 128 if (WasmSym->isGlobal()) 129 report_fatal_error("Global indexes with offsets not supported"); 130 if (WasmSym->isTag()) 131 report_fatal_error("Tag indexes with offsets not supported"); 132 if (WasmSym->isTable()) 133 report_fatal_error("Table indexes with offsets not supported"); 134 135 Expr = MCBinaryExpr::createAdd( 136 Expr, MCConstantExpr::create(MO.getOffset(), Ctx), Ctx); 137 } 138 139 return MCOperand::createExpr(Expr); 140 } 141 142 MCOperand WebAssemblyMCInstLower::lowerTypeIndexOperand( 143 SmallVector<wasm::ValType, 1> &&Returns, 144 SmallVector<wasm::ValType, 4> &&Params) const { 145 auto Signature = std::make_unique<wasm::WasmSignature>(std::move(Returns), 146 std::move(Params)); 147 MCSymbol *Sym = Printer.createTempSymbol("typeindex"); 148 auto *WasmSym = cast<MCSymbolWasm>(Sym); 149 WasmSym->setSignature(Signature.get()); 150 Printer.addSignature(std::move(Signature)); 151 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION); 152 const MCExpr *Expr = 153 MCSymbolRefExpr::create(WasmSym, MCSymbolRefExpr::VK_WASM_TYPEINDEX, Ctx); 154 return MCOperand::createExpr(Expr); 155 } 156 157 // Return the WebAssembly type associated with the given register class. 158 static wasm::ValType getType(const TargetRegisterClass *RC) { 159 if (RC == &WebAssembly::I32RegClass) 160 return wasm::ValType::I32; 161 if (RC == &WebAssembly::I64RegClass) 162 return wasm::ValType::I64; 163 if (RC == &WebAssembly::F32RegClass) 164 return wasm::ValType::F32; 165 if (RC == &WebAssembly::F64RegClass) 166 return wasm::ValType::F64; 167 if (RC == &WebAssembly::V128RegClass) 168 return wasm::ValType::V128; 169 if (RC == &WebAssembly::EXTERNREFRegClass) 170 return wasm::ValType::EXTERNREF; 171 if (RC == &WebAssembly::FUNCREFRegClass) 172 return wasm::ValType::FUNCREF; 173 llvm_unreachable("Unexpected register class"); 174 } 175 176 static void getFunctionReturns(const MachineInstr *MI, 177 SmallVectorImpl<wasm::ValType> &Returns) { 178 const Function &F = MI->getMF()->getFunction(); 179 const TargetMachine &TM = MI->getMF()->getTarget(); 180 Type *RetTy = F.getReturnType(); 181 SmallVector<MVT, 4> CallerRetTys; 182 computeLegalValueVTs(F, TM, RetTy, CallerRetTys); 183 valTypesFromMVTs(CallerRetTys, Returns); 184 } 185 186 void WebAssemblyMCInstLower::lower(const MachineInstr *MI, 187 MCInst &OutMI) const { 188 OutMI.setOpcode(MI->getOpcode()); 189 190 const MCInstrDesc &Desc = MI->getDesc(); 191 unsigned NumVariadicDefs = MI->getNumExplicitDefs() - Desc.getNumDefs(); 192 for (unsigned I = 0, E = MI->getNumOperands(); I != E; ++I) { 193 const MachineOperand &MO = MI->getOperand(I); 194 195 MCOperand MCOp; 196 switch (MO.getType()) { 197 default: 198 MI->print(errs()); 199 llvm_unreachable("unknown operand type"); 200 case MachineOperand::MO_MachineBasicBlock: 201 MI->print(errs()); 202 llvm_unreachable("MachineBasicBlock operand should have been rewritten"); 203 case MachineOperand::MO_Register: { 204 // Ignore all implicit register operands. 205 if (MO.isImplicit()) 206 continue; 207 const WebAssemblyFunctionInfo &MFI = 208 *MI->getParent()->getParent()->getInfo<WebAssemblyFunctionInfo>(); 209 unsigned WAReg = MFI.getWAReg(MO.getReg()); 210 MCOp = MCOperand::createReg(WAReg); 211 break; 212 } 213 case MachineOperand::MO_Immediate: { 214 unsigned DescIndex = I - NumVariadicDefs; 215 if (DescIndex < Desc.NumOperands) { 216 const MCOperandInfo &Info = Desc.OpInfo[DescIndex]; 217 if (Info.OperandType == WebAssembly::OPERAND_TYPEINDEX) { 218 SmallVector<wasm::ValType, 4> Returns; 219 SmallVector<wasm::ValType, 4> Params; 220 221 const MachineRegisterInfo &MRI = 222 MI->getParent()->getParent()->getRegInfo(); 223 for (const MachineOperand &MO : MI->defs()) 224 Returns.push_back(getType(MRI.getRegClass(MO.getReg()))); 225 for (const MachineOperand &MO : MI->explicit_uses()) 226 if (MO.isReg()) 227 Params.push_back(getType(MRI.getRegClass(MO.getReg()))); 228 229 // call_indirect instructions have a callee operand at the end which 230 // doesn't count as a param. 231 if (WebAssembly::isCallIndirect(MI->getOpcode())) 232 Params.pop_back(); 233 234 // return_call_indirect instructions have the return type of the 235 // caller 236 if (MI->getOpcode() == WebAssembly::RET_CALL_INDIRECT) 237 getFunctionReturns(MI, Returns); 238 239 MCOp = lowerTypeIndexOperand(std::move(Returns), std::move(Params)); 240 break; 241 } else if (Info.OperandType == WebAssembly::OPERAND_SIGNATURE) { 242 auto BT = static_cast<WebAssembly::BlockType>(MO.getImm()); 243 assert(BT != WebAssembly::BlockType::Invalid); 244 if (BT == WebAssembly::BlockType::Multivalue) { 245 SmallVector<wasm::ValType, 1> Returns; 246 getFunctionReturns(MI, Returns); 247 MCOp = lowerTypeIndexOperand(std::move(Returns), 248 SmallVector<wasm::ValType, 4>()); 249 break; 250 } 251 } 252 } 253 MCOp = MCOperand::createImm(MO.getImm()); 254 break; 255 } 256 case MachineOperand::MO_FPImmediate: { 257 const ConstantFP *Imm = MO.getFPImm(); 258 const uint64_t BitPattern = 259 Imm->getValueAPF().bitcastToAPInt().getZExtValue(); 260 if (Imm->getType()->isFloatTy()) 261 MCOp = MCOperand::createSFPImm(static_cast<uint32_t>(BitPattern)); 262 else if (Imm->getType()->isDoubleTy()) 263 MCOp = MCOperand::createDFPImm(BitPattern); 264 else 265 llvm_unreachable("unknown floating point immediate type"); 266 break; 267 } 268 case MachineOperand::MO_GlobalAddress: 269 MCOp = lowerSymbolOperand(MO, GetGlobalAddressSymbol(MO)); 270 break; 271 case MachineOperand::MO_ExternalSymbol: 272 MCOp = lowerSymbolOperand(MO, GetExternalSymbolSymbol(MO)); 273 break; 274 case MachineOperand::MO_MCSymbol: 275 assert(MO.getTargetFlags() == 0 && 276 "WebAssembly does not use target flags on MCSymbol"); 277 MCOp = lowerSymbolOperand(MO, MO.getMCSymbol()); 278 break; 279 } 280 281 OutMI.addOperand(MCOp); 282 } 283 284 if (!WasmKeepRegisters) 285 removeRegisterOperands(MI, OutMI); 286 else if (Desc.variadicOpsAreDefs()) 287 OutMI.insert(OutMI.begin(), MCOperand::createImm(MI->getNumExplicitDefs())); 288 } 289 290 static void removeRegisterOperands(const MachineInstr *MI, MCInst &OutMI) { 291 // Remove all uses of stackified registers to bring the instruction format 292 // into its final stack form used thruout MC, and transition opcodes to 293 // their _S variant. 294 // We do this separate from the above code that still may need these 295 // registers for e.g. call_indirect signatures. 296 // See comments in lib/Target/WebAssembly/WebAssemblyInstrFormats.td for 297 // details. 298 // TODO: the code above creates new registers which are then removed here. 299 // That code could be slightly simplified by not doing that, though maybe 300 // it is simpler conceptually to keep the code above in "register mode" 301 // until this transition point. 302 // FIXME: we are not processing inline assembly, which contains register 303 // operands, because it is used by later target generic code. 304 if (MI->isDebugInstr() || MI->isLabel() || MI->isInlineAsm()) 305 return; 306 307 // Transform to _S instruction. 308 auto RegOpcode = OutMI.getOpcode(); 309 auto StackOpcode = WebAssembly::getStackOpcode(RegOpcode); 310 assert(StackOpcode != -1 && "Failed to stackify instruction"); 311 OutMI.setOpcode(StackOpcode); 312 313 // Remove register operands. 314 for (auto I = OutMI.getNumOperands(); I; --I) { 315 auto &MO = OutMI.getOperand(I - 1); 316 if (MO.isReg()) { 317 OutMI.erase(&MO); 318 } 319 } 320 } 321