1 //===- SubtargetFeature.cpp - CPU characteristics Implementation ----------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file implements the SubtargetFeature interface. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "llvm/MC/SubtargetFeature.h" 15 #include "llvm/Support/Debug.h" 16 #include "llvm/Support/Format.h" 17 #include "llvm/Support/raw_ostream.h" 18 #include <algorithm> 19 #include <cassert> 20 #include <cctype> 21 #include <cstdlib> 22 using namespace llvm; 23 24 //===----------------------------------------------------------------------===// 25 // Static Helper Functions 26 //===----------------------------------------------------------------------===// 27 28 /// hasFlag - Determine if a feature has a flag; '+' or '-' 29 /// 30 static inline bool hasFlag(const StringRef Feature) { 31 assert(!Feature.empty() && "Empty string"); 32 // Get first character 33 char Ch = Feature[0]; 34 // Check if first character is '+' or '-' flag 35 return Ch == '+' || Ch =='-'; 36 } 37 38 /// StripFlag - Return string stripped of flag. 39 /// 40 static inline std::string StripFlag(const StringRef Feature) { 41 return hasFlag(Feature) ? Feature.substr(1) : Feature; 42 } 43 44 /// isEnabled - Return true if enable flag; '+'. 45 /// 46 static inline bool isEnabled(const StringRef Feature) { 47 assert(!Feature.empty() && "Empty string"); 48 // Get first character 49 char Ch = Feature[0]; 50 // Check if first character is '+' for enabled 51 return Ch == '+'; 52 } 53 54 /// Split - Splits a string of comma separated items in to a vector of strings. 55 /// 56 static void Split(std::vector<std::string> &V, const StringRef S) { 57 SmallVector<StringRef, 2> Tmp; 58 S.split(Tmp, ",", -1, false /* KeepEmpty */); 59 V.assign(Tmp.begin(), Tmp.end()); 60 } 61 62 /// Join a vector of strings to a string with a comma separating each element. 63 /// 64 static std::string Join(const std::vector<std::string> &V) { 65 // Start with empty string. 66 std::string Result; 67 // If the vector is not empty 68 if (!V.empty()) { 69 // Start with the first feature 70 Result = V[0]; 71 // For each successive feature 72 for (size_t i = 1; i < V.size(); i++) { 73 // Add a comma 74 Result += ","; 75 // Add the feature 76 Result += V[i]; 77 } 78 } 79 // Return the features string 80 return Result; 81 } 82 83 /// Adding features. 84 void SubtargetFeatures::AddFeature(const StringRef String) { 85 // Don't add empty features or features we already have. 86 if (!String.empty()) 87 // Convert to lowercase, prepend flag if we don't already have a flag. 88 Features.push_back(hasFlag(String) ? String.str() : "+" + String.lower()); 89 } 90 91 /// Find KV in array using binary search. 92 static const SubtargetFeatureKV *Find(StringRef S, 93 ArrayRef<SubtargetFeatureKV> A) { 94 // Binary search the array 95 auto F = std::lower_bound(A.begin(), A.end(), S); 96 // If not found then return NULL 97 if (F == A.end() || StringRef(F->Key) != S) return nullptr; 98 // Return the found array item 99 return F; 100 } 101 102 /// getLongestEntryLength - Return the length of the longest entry in the table. 103 /// 104 static size_t getLongestEntryLength(ArrayRef<SubtargetFeatureKV> Table) { 105 size_t MaxLen = 0; 106 for (auto &I : Table) 107 MaxLen = std::max(MaxLen, std::strlen(I.Key)); 108 return MaxLen; 109 } 110 111 /// Display help for feature choices. 112 /// 113 static void Help(ArrayRef<SubtargetFeatureKV> CPUTable, 114 ArrayRef<SubtargetFeatureKV> FeatTable) { 115 // Determine the length of the longest CPU and Feature entries. 116 unsigned MaxCPULen = getLongestEntryLength(CPUTable); 117 unsigned MaxFeatLen = getLongestEntryLength(FeatTable); 118 119 // Print the CPU table. 120 errs() << "Available CPUs for this target:\n\n"; 121 for (auto &CPU : CPUTable) 122 errs() << format(" %-*s - %s.\n", MaxCPULen, CPU.Key, CPU.Desc); 123 errs() << '\n'; 124 125 // Print the Feature table. 126 errs() << "Available features for this target:\n\n"; 127 for (auto &Feature : FeatTable) 128 errs() << format(" %-*s - %s.\n", MaxFeatLen, Feature.Key, Feature.Desc); 129 errs() << '\n'; 130 131 errs() << "Use +feature to enable a feature, or -feature to disable it.\n" 132 "For example, llc -mcpu=mycpu -mattr=+feature1,-feature2\n"; 133 } 134 135 //===----------------------------------------------------------------------===// 136 // SubtargetFeatures Implementation 137 //===----------------------------------------------------------------------===// 138 139 SubtargetFeatures::SubtargetFeatures(const StringRef Initial) { 140 // Break up string into separate features 141 Split(Features, Initial); 142 } 143 144 145 std::string SubtargetFeatures::getString() const { 146 return Join(Features); 147 } 148 149 /// SetImpliedBits - For each feature that is (transitively) implied by this 150 /// feature, set it. 151 /// 152 static 153 void SetImpliedBits(uint64_t &Bits, const SubtargetFeatureKV *FeatureEntry, 154 ArrayRef<SubtargetFeatureKV> FeatureTable) { 155 for (auto &FE : FeatureTable) { 156 if (FeatureEntry->Value == FE.Value) continue; 157 158 if (FeatureEntry->Implies & FE.Value) { 159 Bits |= FE.Value; 160 SetImpliedBits(Bits, &FE, FeatureTable); 161 } 162 } 163 } 164 165 /// ClearImpliedBits - For each feature that (transitively) implies this 166 /// feature, clear it. 167 /// 168 static 169 void ClearImpliedBits(uint64_t &Bits, const SubtargetFeatureKV *FeatureEntry, 170 ArrayRef<SubtargetFeatureKV> FeatureTable) { 171 for (auto &FE : FeatureTable) { 172 if (FeatureEntry->Value == FE.Value) continue; 173 174 if (FE.Implies & FeatureEntry->Value) { 175 Bits &= ~FE.Value; 176 ClearImpliedBits(Bits, &FE, FeatureTable); 177 } 178 } 179 } 180 181 /// ToggleFeature - Toggle a feature and returns the newly updated feature 182 /// bits. 183 uint64_t 184 SubtargetFeatures::ToggleFeature(uint64_t Bits, const StringRef Feature, 185 ArrayRef<SubtargetFeatureKV> FeatureTable) { 186 187 // Find feature in table. 188 const SubtargetFeatureKV *FeatureEntry = 189 Find(StripFlag(Feature), FeatureTable); 190 // If there is a match 191 if (FeatureEntry) { 192 if ((Bits & FeatureEntry->Value) == FeatureEntry->Value) { 193 Bits &= ~FeatureEntry->Value; 194 195 // For each feature that implies this, clear it. 196 ClearImpliedBits(Bits, FeatureEntry, FeatureTable); 197 } else { 198 Bits |= FeatureEntry->Value; 199 200 // For each feature that this implies, set it. 201 SetImpliedBits(Bits, FeatureEntry, FeatureTable); 202 } 203 } else { 204 errs() << "'" << Feature 205 << "' is not a recognized feature for this target" 206 << " (ignoring feature)\n"; 207 } 208 209 return Bits; 210 } 211 212 213 /// getFeatureBits - Get feature bits a CPU. 214 /// 215 uint64_t 216 SubtargetFeatures::getFeatureBits(const StringRef CPU, 217 ArrayRef<SubtargetFeatureKV> CPUTable, 218 ArrayRef<SubtargetFeatureKV> FeatureTable) { 219 220 if (CPUTable.empty() || FeatureTable.empty()) 221 return 0; 222 223 #ifndef NDEBUG 224 for (size_t i = 1, e = CPUTable.size(); i != e; ++i) { 225 assert(strcmp(CPUTable[i - 1].Key, CPUTable[i].Key) < 0 && 226 "CPU table is not sorted"); 227 } 228 for (size_t i = 1, e = FeatureTable.size(); i != e; ++i) { 229 assert(strcmp(FeatureTable[i - 1].Key, FeatureTable[i].Key) < 0 && 230 "CPU features table is not sorted"); 231 } 232 #endif 233 uint64_t Bits = 0; // Resulting bits 234 235 // Check if help is needed 236 if (CPU == "help") 237 Help(CPUTable, FeatureTable); 238 239 // Find CPU entry if CPU name is specified. 240 else if (!CPU.empty()) { 241 const SubtargetFeatureKV *CPUEntry = Find(CPU, CPUTable); 242 243 // If there is a match 244 if (CPUEntry) { 245 // Set base feature bits 246 Bits = CPUEntry->Value; 247 248 // Set the feature implied by this CPU feature, if any. 249 for (auto &FE : FeatureTable) { 250 if (CPUEntry->Value & FE.Value) 251 SetImpliedBits(Bits, &FE, FeatureTable); 252 } 253 } else { 254 errs() << "'" << CPU 255 << "' is not a recognized processor for this target" 256 << " (ignoring processor)\n"; 257 } 258 } 259 260 // Iterate through each feature 261 for (auto &Feature : Features) { 262 // Check for help 263 if (Feature == "+help") 264 Help(CPUTable, FeatureTable); 265 266 // Find feature in table. 267 const SubtargetFeatureKV *FeatureEntry = 268 Find(StripFlag(Feature), FeatureTable); 269 // If there is a match 270 if (FeatureEntry) { 271 // Enable/disable feature in bits 272 if (isEnabled(Feature)) { 273 Bits |= FeatureEntry->Value; 274 275 // For each feature that this implies, set it. 276 SetImpliedBits(Bits, FeatureEntry, FeatureTable); 277 } else { 278 Bits &= ~FeatureEntry->Value; 279 280 // For each feature that implies this, clear it. 281 ClearImpliedBits(Bits, FeatureEntry, FeatureTable); 282 } 283 } else { 284 errs() << "'" << Feature 285 << "' is not a recognized feature for this target" 286 << " (ignoring feature)\n"; 287 } 288 } 289 290 return Bits; 291 } 292 293 /// print - Print feature string. 294 /// 295 void SubtargetFeatures::print(raw_ostream &OS) const { 296 for (auto &F : Features) 297 OS << F << " "; 298 OS << "\n"; 299 } 300 301 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 302 /// dump - Dump feature info. 303 /// 304 void SubtargetFeatures::dump() const { 305 print(dbgs()); 306 } 307 #endif 308 309 /// Adds the default features for the specified target triple. 310 /// 311 /// FIXME: This is an inelegant way of specifying the features of a 312 /// subtarget. It would be better if we could encode this information 313 /// into the IR. See <rdar://5972456>. 314 /// 315 void SubtargetFeatures::getDefaultSubtargetFeatures(const Triple& Triple) { 316 if (Triple.getVendor() == Triple::Apple) { 317 if (Triple.getArch() == Triple::ppc) { 318 // powerpc-apple-* 319 AddFeature("altivec"); 320 } else if (Triple.getArch() == Triple::ppc64) { 321 // powerpc64-apple-* 322 AddFeature("64bit"); 323 AddFeature("altivec"); 324 } 325 } 326 } 327
