1 //===- RegisterBankEmitter.cpp - Generate a Register Bank Desc. -*- C++ -*-===// 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 // This tablegen backend is responsible for emitting a description of a target 10 // register bank for a code generator. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "CodeGenRegisters.h" 15 #include "CodeGenTarget.h" 16 #include "InfoByHwMode.h" 17 #include "llvm/ADT/BitVector.h" 18 #include "llvm/Support/Debug.h" 19 #include "llvm/TableGen/Error.h" 20 #include "llvm/TableGen/Record.h" 21 #include "llvm/TableGen/TableGenBackend.h" 22 23 #define DEBUG_TYPE "register-bank-emitter" 24 25 using namespace llvm; 26 27 namespace { 28 class RegisterBank { 29 30 /// A vector of register classes that are included in the register bank. 31 typedef std::vector<const CodeGenRegisterClass *> RegisterClassesTy; 32 33 private: 34 const Record &TheDef; 35 36 /// The register classes that are covered by the register bank. 37 RegisterClassesTy RCs; 38 39 /// The register class with the largest register size. 40 std::vector<const CodeGenRegisterClass *> RCsWithLargestRegSize; 41 42 public: 43 RegisterBank(const Record &TheDef, unsigned NumModeIds) 44 : TheDef(TheDef), RCsWithLargestRegSize(NumModeIds) {} 45 46 /// Get the human-readable name for the bank. 47 StringRef getName() const { return TheDef.getValueAsString("Name"); } 48 /// Get the name of the enumerator in the ID enumeration. 49 std::string getEnumeratorName() const { return (TheDef.getName() + "ID").str(); } 50 51 /// Get the name of the array holding the register class coverage data; 52 std::string getCoverageArrayName() const { 53 return (TheDef.getName() + "CoverageData").str(); 54 } 55 56 /// Get the name of the global instance variable. 57 StringRef getInstanceVarName() const { return TheDef.getName(); } 58 59 const Record &getDef() const { return TheDef; } 60 61 /// Get the register classes listed in the RegisterBank.RegisterClasses field. 62 std::vector<const CodeGenRegisterClass *> 63 getExplicitlySpecifiedRegisterClasses( 64 const CodeGenRegBank &RegisterClassHierarchy) const { 65 std::vector<const CodeGenRegisterClass *> RCs; 66 for (const auto *RCDef : getDef().getValueAsListOfDefs("RegisterClasses")) 67 RCs.push_back(RegisterClassHierarchy.getRegClass(RCDef)); 68 return RCs; 69 } 70 71 /// Add a register class to the bank without duplicates. 72 void addRegisterClass(const CodeGenRegisterClass *RC) { 73 if (llvm::is_contained(RCs, RC)) 74 return; 75 76 // FIXME? We really want the register size rather than the spill size 77 // since the spill size may be bigger on some targets with 78 // limited load/store instructions. However, we don't store the 79 // register size anywhere (we could sum the sizes of the subregisters 80 // but there may be additional bits too) and we can't derive it from 81 // the VT's reliably due to Untyped. 82 unsigned NumModeIds = RCsWithLargestRegSize.size(); 83 for (unsigned M = 0; M < NumModeIds; ++M) { 84 if (RCsWithLargestRegSize[M] == nullptr) 85 RCsWithLargestRegSize[M] = RC; 86 else if (RCsWithLargestRegSize[M]->RSI.get(M).SpillSize < 87 RC->RSI.get(M).SpillSize) 88 RCsWithLargestRegSize[M] = RC; 89 assert(RCsWithLargestRegSize[M] && "RC was nullptr?"); 90 } 91 92 RCs.emplace_back(RC); 93 } 94 95 const CodeGenRegisterClass *getRCWithLargestRegSize(unsigned HwMode) const { 96 return RCsWithLargestRegSize[HwMode]; 97 } 98 99 iterator_range<typename RegisterClassesTy::const_iterator> 100 register_classes() const { 101 return llvm::make_range(RCs.begin(), RCs.end()); 102 } 103 }; 104 105 class RegisterBankEmitter { 106 private: 107 CodeGenTarget Target; 108 RecordKeeper &Records; 109 110 void emitHeader(raw_ostream &OS, const StringRef TargetName, 111 const std::vector<RegisterBank> &Banks); 112 void emitBaseClassDefinition(raw_ostream &OS, const StringRef TargetName, 113 const std::vector<RegisterBank> &Banks); 114 void emitBaseClassImplementation(raw_ostream &OS, const StringRef TargetName, 115 std::vector<RegisterBank> &Banks); 116 117 public: 118 RegisterBankEmitter(RecordKeeper &R) : Target(R), Records(R) {} 119 120 void run(raw_ostream &OS); 121 }; 122 123 } // end anonymous namespace 124 125 /// Emit code to declare the ID enumeration and external global instance 126 /// variables. 127 void RegisterBankEmitter::emitHeader(raw_ostream &OS, 128 const StringRef TargetName, 129 const std::vector<RegisterBank> &Banks) { 130 // <Target>RegisterBankInfo.h 131 OS << "namespace llvm {\n" 132 << "namespace " << TargetName << " {\n" 133 << "enum : unsigned {\n"; 134 135 OS << " InvalidRegBankID = ~0u,\n"; 136 unsigned ID = 0; 137 for (const auto &Bank : Banks) 138 OS << " " << Bank.getEnumeratorName() << " = " << ID++ << ",\n"; 139 OS << " NumRegisterBanks,\n" 140 << "};\n" 141 << "} // end namespace " << TargetName << "\n" 142 << "} // end namespace llvm\n"; 143 } 144 145 /// Emit declarations of the <Target>GenRegisterBankInfo class. 146 void RegisterBankEmitter::emitBaseClassDefinition( 147 raw_ostream &OS, const StringRef TargetName, 148 const std::vector<RegisterBank> &Banks) { 149 OS << "private:\n" 150 << " static const RegisterBank *RegBanks[];\n" 151 << " static const unsigned Sizes[];\n\n" 152 << "protected:\n" 153 << " " << TargetName << "GenRegisterBankInfo(unsigned HwMode = 0);\n" 154 << "\n"; 155 } 156 157 /// Visit each register class belonging to the given register bank. 158 /// 159 /// A class belongs to the bank iff any of these apply: 160 /// * It is explicitly specified 161 /// * It is a subclass of a class that is a member. 162 /// * It is a class containing subregisters of the registers of a class that 163 /// is a member. This is known as a subreg-class. 164 /// 165 /// This function must be called for each explicitly specified register class. 166 /// 167 /// \param RC The register class to search. 168 /// \param Kind A debug string containing the path the visitor took to reach RC. 169 /// \param VisitFn The action to take for each class visited. It may be called 170 /// multiple times for a given class if there are multiple paths 171 /// to the class. 172 static void visitRegisterBankClasses( 173 const CodeGenRegBank &RegisterClassHierarchy, 174 const CodeGenRegisterClass *RC, const Twine &Kind, 175 std::function<void(const CodeGenRegisterClass *, StringRef)> VisitFn, 176 SmallPtrSetImpl<const CodeGenRegisterClass *> &VisitedRCs) { 177 178 // Make sure we only visit each class once to avoid infinite loops. 179 if (!VisitedRCs.insert(RC).second) 180 return; 181 182 // Visit each explicitly named class. 183 VisitFn(RC, Kind.str()); 184 185 for (const auto &PossibleSubclass : RegisterClassHierarchy.getRegClasses()) { 186 std::string TmpKind = 187 (Kind + " (" + PossibleSubclass.getName() + ")").str(); 188 189 // Visit each subclass of an explicitly named class. 190 if (RC != &PossibleSubclass && RC->hasSubClass(&PossibleSubclass)) 191 visitRegisterBankClasses(RegisterClassHierarchy, &PossibleSubclass, 192 TmpKind + " " + RC->getName() + " subclass", 193 VisitFn, VisitedRCs); 194 195 // Visit each class that contains only subregisters of RC with a common 196 // subregister-index. 197 // 198 // More precisely, PossibleSubclass is a subreg-class iff Reg:SubIdx is in 199 // PossibleSubclass for all registers Reg from RC using any 200 // subregister-index SubReg 201 for (const auto &SubIdx : RegisterClassHierarchy.getSubRegIndices()) { 202 BitVector BV(RegisterClassHierarchy.getRegClasses().size()); 203 PossibleSubclass.getSuperRegClasses(&SubIdx, BV); 204 if (BV.test(RC->EnumValue)) { 205 std::string TmpKind2 = (Twine(TmpKind) + " " + RC->getName() + 206 " class-with-subregs: " + RC->getName()) 207 .str(); 208 VisitFn(&PossibleSubclass, TmpKind2); 209 } 210 } 211 } 212 } 213 214 void RegisterBankEmitter::emitBaseClassImplementation( 215 raw_ostream &OS, StringRef TargetName, 216 std::vector<RegisterBank> &Banks) { 217 const CodeGenRegBank &RegisterClassHierarchy = Target.getRegBank(); 218 const CodeGenHwModes &CGH = Target.getHwModes(); 219 220 OS << "namespace llvm {\n" 221 << "namespace " << TargetName << " {\n"; 222 for (const auto &Bank : Banks) { 223 std::vector<std::vector<const CodeGenRegisterClass *>> RCsGroupedByWord( 224 (RegisterClassHierarchy.getRegClasses().size() + 31) / 32); 225 226 for (const auto &RC : Bank.register_classes()) 227 RCsGroupedByWord[RC->EnumValue / 32].push_back(RC); 228 229 OS << "const uint32_t " << Bank.getCoverageArrayName() << "[] = {\n"; 230 unsigned LowestIdxInWord = 0; 231 for (const auto &RCs : RCsGroupedByWord) { 232 OS << " // " << LowestIdxInWord << "-" << (LowestIdxInWord + 31) << "\n"; 233 for (const auto &RC : RCs) { 234 OS << " (1u << (" << RC->getQualifiedIdName() << " - " 235 << LowestIdxInWord << ")) |\n"; 236 } 237 OS << " 0,\n"; 238 LowestIdxInWord += 32; 239 } 240 OS << "};\n"; 241 } 242 OS << "\n"; 243 244 for (const auto &Bank : Banks) { 245 std::string QualifiedBankID = 246 (TargetName + "::" + Bank.getEnumeratorName()).str(); 247 OS << "constexpr RegisterBank " << Bank.getInstanceVarName() << "(/* ID */ " 248 << QualifiedBankID << ", /* Name */ \"" << Bank.getName() << "\", " 249 << "/* CoveredRegClasses */ " << Bank.getCoverageArrayName() 250 << ", /* NumRegClasses */ " 251 << RegisterClassHierarchy.getRegClasses().size() << ");\n"; 252 } 253 OS << "} // end namespace " << TargetName << "\n" 254 << "\n"; 255 256 OS << "const RegisterBank *" << TargetName 257 << "GenRegisterBankInfo::RegBanks[] = {\n"; 258 for (const auto &Bank : Banks) 259 OS << " &" << TargetName << "::" << Bank.getInstanceVarName() << ",\n"; 260 OS << "};\n\n"; 261 262 unsigned NumModeIds = CGH.getNumModeIds(); 263 OS << "const unsigned " << TargetName << "GenRegisterBankInfo::Sizes[] = {\n"; 264 for (unsigned M = 0; M < NumModeIds; ++M) { 265 OS << " // Mode = " << M << " ("; 266 if (M == DefaultMode) 267 OS << "Default"; 268 else 269 OS << CGH.getMode(M).Name; 270 OS << ")\n"; 271 for (const auto &Bank : Banks) { 272 const CodeGenRegisterClass &RC = *Bank.getRCWithLargestRegSize(M); 273 unsigned Size = RC.RSI.get(M).SpillSize; 274 OS << " " << Size << ",\n"; 275 } 276 } 277 OS << "};\n\n"; 278 279 OS << TargetName << "GenRegisterBankInfo::" << TargetName 280 << "GenRegisterBankInfo(unsigned HwMode)\n" 281 << " : RegisterBankInfo(RegBanks, " << TargetName 282 << "::NumRegisterBanks, Sizes, HwMode) {\n" 283 << " // Assert that RegBank indices match their ID's\n" 284 << "#ifndef NDEBUG\n" 285 << " for (auto RB : enumerate(RegBanks))\n" 286 << " assert(RB.index() == RB.value()->getID() && \"Index != ID\");\n" 287 << "#endif // NDEBUG\n" 288 << "}\n" 289 << "} // end namespace llvm\n"; 290 } 291 292 void RegisterBankEmitter::run(raw_ostream &OS) { 293 StringRef TargetName = Target.getName(); 294 const CodeGenRegBank &RegisterClassHierarchy = Target.getRegBank(); 295 const CodeGenHwModes &CGH = Target.getHwModes(); 296 297 Records.startTimer("Analyze records"); 298 std::vector<RegisterBank> Banks; 299 for (const auto &V : Records.getAllDerivedDefinitions("RegisterBank")) { 300 SmallPtrSet<const CodeGenRegisterClass *, 8> VisitedRCs; 301 RegisterBank Bank(*V, CGH.getNumModeIds()); 302 303 for (const CodeGenRegisterClass *RC : 304 Bank.getExplicitlySpecifiedRegisterClasses(RegisterClassHierarchy)) { 305 visitRegisterBankClasses( 306 RegisterClassHierarchy, RC, "explicit", 307 [&Bank](const CodeGenRegisterClass *RC, StringRef Kind) { 308 LLVM_DEBUG(dbgs() 309 << "Added " << RC->getName() << "(" << Kind << ")\n"); 310 Bank.addRegisterClass(RC); 311 }, 312 VisitedRCs); 313 } 314 315 Banks.push_back(Bank); 316 } 317 318 // Warn about ambiguous MIR caused by register bank/class name clashes. 319 Records.startTimer("Warn ambiguous"); 320 for (const auto &Class : RegisterClassHierarchy.getRegClasses()) { 321 for (const auto &Bank : Banks) { 322 if (Bank.getName().lower() == StringRef(Class.getName()).lower()) { 323 PrintWarning(Bank.getDef().getLoc(), "Register bank names should be " 324 "distinct from register classes " 325 "to avoid ambiguous MIR"); 326 PrintNote(Bank.getDef().getLoc(), "RegisterBank was declared here"); 327 PrintNote(Class.getDef()->getLoc(), "RegisterClass was declared here"); 328 } 329 } 330 } 331 332 Records.startTimer("Emit output"); 333 emitSourceFileHeader("Register Bank Source Fragments", OS); 334 OS << "#ifdef GET_REGBANK_DECLARATIONS\n" 335 << "#undef GET_REGBANK_DECLARATIONS\n"; 336 emitHeader(OS, TargetName, Banks); 337 OS << "#endif // GET_REGBANK_DECLARATIONS\n\n" 338 << "#ifdef GET_TARGET_REGBANK_CLASS\n" 339 << "#undef GET_TARGET_REGBANK_CLASS\n"; 340 emitBaseClassDefinition(OS, TargetName, Banks); 341 OS << "#endif // GET_TARGET_REGBANK_CLASS\n\n" 342 << "#ifdef GET_TARGET_REGBANK_IMPL\n" 343 << "#undef GET_TARGET_REGBANK_IMPL\n"; 344 emitBaseClassImplementation(OS, TargetName, Banks); 345 OS << "#endif // GET_TARGET_REGBANK_IMPL\n"; 346 } 347 348 static TableGen::Emitter::OptClass<RegisterBankEmitter> 349 X("gen-register-bank", "Generate registers bank descriptions"); 350