lib/Target/SubtargetFeature.cpp

   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/Target/SubtargetFeature.h"
  15 #include "llvm/Support/Debug.h"
  16 #include "llvm/Support/raw_ostream.h"
  17 #include "llvm/ADT/StringExtras.h"
  18 #include <algorithm>
  19 #include <cassert>
  20 #include <cctype>
  21 using namespace llvm;
  22
  23 //===----------------------------------------------------------------------===//
  24 //                          Static Helper Functions
  25 //===----------------------------------------------------------------------===//
  26
  27 /// hasFlag - Determine if a feature has a flag; '+' or '-'
  28 ///
  29 static inline bool hasFlag(const std::string &Feature) {
  30   assert(!Feature.empty() && "Empty string");
  31   // Get first character
  32   char Ch = Feature[0];
  33   // Check if first character is '+' or '-' flag
  34   return Ch == '+' || Ch =='-';
  35 }
  36
  37 /// StripFlag - Return string stripped of flag.
  38 ///
  39 static inline std::string StripFlag(const std::string &Feature) {
  40   return hasFlag(Feature) ? Feature.substr(1) : Feature;
  41 }
  42
  43 /// isEnabled - Return true if enable flag; '+'.
  44 ///
  45 static inline bool isEnabled(const std::string &Feature) {
  46   assert(!Feature.empty() && "Empty string");
  47   // Get first character
  48   char Ch = Feature[0];
  49   // Check if first character is '+' for enabled
  50   return Ch == '+';
  51 }
  52
  53 /// PrependFlag - Return a string with a prepended flag; '+' or '-'.
  54 ///
  55 static inline std::string PrependFlag(const std::string &Feature,
  56                                       bool IsEnabled) {
  57   assert(!Feature.empty() && "Empty string");
  58   if (hasFlag(Feature)) return Feature;
  59   return std::string(IsEnabled ? "+" : "-") + Feature;
  60 }
  61
  62 /// Split - Splits a string of comma separated items in to a vector of strings.
  63 ///
  64 static void Split(std::vector<std::string> &V, const std::string &S) {
  65   // Start at beginning of string.
  66   size_t Pos = 0;
  67   while (true) {
  68     // Find the next comma
  69     size_t Comma = S.find(',', Pos);
  70     // If no comma found then the rest of the string is used
  71     if (Comma == std::string::npos) {
  72       // Add string to vector
  73       V.push_back(S.substr(Pos));
  74       break;
  75     }
  76     // Otherwise add substring to vector
  77     V.push_back(S.substr(Pos, Comma - Pos));
  78     // Advance to next item
  79     Pos = Comma + 1;
  80   }
  81 }
  82
  83 /// Join a vector of strings to a string with a comma separating each element.
  84 ///
  85 static std::string Join(const std::vector<std::string> &V) {
  86   // Start with empty string.
  87   std::string Result;
  88   // If the vector is not empty
  89   if (!V.empty()) {
  90     // Start with the CPU feature
  91     Result = V[0];
  92     // For each successive feature
  93     for (size_t i = 1; i < V.size(); i++) {
  94       // Add a comma
  95       Result += ",";
  96       // Add the feature
  97       Result += V[i];
  98     }
  99   }
 100   // Return the features string
 101   return Result;
 102 }
 103
 104 /// Adding features.
 105 void SubtargetFeatures::AddFeature(const std::string &String,
 106                                    bool IsEnabled) {
 107   // Don't add empty features
 108   if (!String.empty()) {
 109     // Convert to lowercase, prepend flag and add to vector
 110     Features.push_back(PrependFlag(LowercaseString(String), IsEnabled));
 111   }
 112 }
 113
 114 /// Find KV in array using binary search.
 115 template<typename T> const T *Find(const std::string &S, const T *A, size_t L) {
 116   // Make the lower bound element we're looking for
 117   T KV;
 118   KV.Key = S.c_str();
 119   // Determine the end of the array
 120   const T *Hi = A + L;
 121   // Binary search the array
 122   const T *F = std::lower_bound(A, Hi, KV);
 123   // If not found then return NULL
 124   if (F == Hi || std::string(F->Key) != S) return NULL;
 125   // Return the found array item
 126   return F;
 127 }
 128
 129 /// getLongestEntryLength - Return the length of the longest entry in the table.
 130 ///
 131 static size_t getLongestEntryLength(const SubtargetFeatureKV *Table,
 132                                     size_t Size) {
 133   size_t MaxLen = 0;
 134   for (size_t i = 0; i < Size; i++)
 135     MaxLen = std::max(MaxLen, std::strlen(Table[i].Key));
 136   return MaxLen;
 137 }
 138
 139 /// Display help for feature choices.
 140 ///
 141 static void Help(const SubtargetFeatureKV *CPUTable, size_t CPUTableSize,
 142                  const SubtargetFeatureKV *FeatTable, size_t FeatTableSize) {
 143   // Determine the length of the longest CPU and Feature entries.
 144   unsigned MaxCPULen  = getLongestEntryLength(CPUTable, CPUTableSize);
 145   unsigned MaxFeatLen = getLongestEntryLength(FeatTable, FeatTableSize);
 146
 147   // Print the CPU table.
 148   errs() << "Available CPUs for this target:\n\n";
 149   for (size_t i = 0; i != CPUTableSize; i++)
 150     errs() << "  " << CPUTable[i].Key
 151          << std::string(MaxCPULen - std::strlen(CPUTable[i].Key), ' ')
 152          << " - " << CPUTable[i].Desc << ".\n";
 153   errs() << "\n";
 154
 155   // Print the Feature table.
 156   errs() << "Available features for this target:\n\n";
 157   for (size_t i = 0; i != FeatTableSize; i++)
 158     errs() << "  " << FeatTable[i].Key
 159          << std::string(MaxFeatLen - std::strlen(FeatTable[i].Key), ' ')
 160          << " - " << FeatTable[i].Desc << ".\n";
 161   errs() << "\n";
 162
 163   errs() << "Use +feature to enable a feature, or -feature to disable it.\n"
 164        << "For example, llc -mcpu=mycpu -mattr=+feature1,-feature2\n";
 165   exit(1);
 166 }
 167
 168 //===----------------------------------------------------------------------===//
 169 //                    SubtargetFeatures Implementation
 170 //===----------------------------------------------------------------------===//
 171
 172 SubtargetFeatures::SubtargetFeatures(const std::string &Initial) {
 173   // Break up string into separate features
 174   Split(Features, Initial);
 175 }
 176
 177
 178 std::string SubtargetFeatures::getString() const {
 179   return Join(Features);
 180 }
 181 void SubtargetFeatures::setString(const std::string &Initial) {
 182   // Throw out old features
 183   Features.clear();
 184   // Break up string into separate features
 185   Split(Features, LowercaseString(Initial));
 186 }
 187
 188
 189 /// setCPU - Set the CPU string.  Replaces previous setting.  Setting to ""
 190 /// clears CPU.
 191 void SubtargetFeatures::setCPU(const std::string &String) {
 192   Features[0] = LowercaseString(String);
 193 }
 194
 195
 196 /// setCPUIfNone - Setting CPU string only if no string is set.
 197 ///
 198 void SubtargetFeatures::setCPUIfNone(const std::string &String) {
 199   if (Features[0].empty()) setCPU(String);
 200 }
 201
 202 /// getCPU - Returns current CPU.
 203 ///
 204 const std::string & SubtargetFeatures::getCPU() const {
 205   return Features[0];
 206 }
 207
 208
 209 /// SetImpliedBits - For each feature that is (transitively) implied by this
 210 /// feature, set it.
 211 ///
 212 static
 213 void SetImpliedBits(uint32_t &Bits, const SubtargetFeatureKV *FeatureEntry,
 214                     const SubtargetFeatureKV *FeatureTable,
 215                     size_t FeatureTableSize) {
 216   for (size_t i = 0; i < FeatureTableSize; ++i) {
 217     const SubtargetFeatureKV &FE = FeatureTable[i];
 218
 219     if (FeatureEntry->Value == FE.Value) continue;
 220
 221     if (FeatureEntry->Implies & FE.Value) {
 222       Bits |= FE.Value;
 223       SetImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
 224     }
 225   }
 226 }
 227
 228 /// ClearImpliedBits - For each feature that (transitively) implies this
 229 /// feature, clear it.
 230 ///
 231 static
 232 void ClearImpliedBits(uint32_t &Bits, const SubtargetFeatureKV *FeatureEntry,
 233                       const SubtargetFeatureKV *FeatureTable,
 234                       size_t FeatureTableSize) {
 235   for (size_t i = 0; i < FeatureTableSize; ++i) {
 236     const SubtargetFeatureKV &FE = FeatureTable[i];
 237
 238     if (FeatureEntry->Value == FE.Value) continue;
 239
 240     if (FE.Implies & FeatureEntry->Value) {
 241       Bits &= ~FE.Value;
 242       ClearImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
 243     }
 244   }
 245 }
 246
 247 /// getBits - Get feature bits.
 248 ///
 249 uint32_t SubtargetFeatures::getBits(const SubtargetFeatureKV *CPUTable,
 250                                           size_t CPUTableSize,
 251                                     const SubtargetFeatureKV *FeatureTable,
 252                                           size_t FeatureTableSize) {
 253   assert(CPUTable && "missing CPU table");
 254   assert(FeatureTable && "missing features table");
 255 #ifndef NDEBUG
 256   for (size_t i = 1; i < CPUTableSize; i++) {
 257     assert(strcmp(CPUTable[i - 1].Key, CPUTable[i].Key) < 0 &&
 258            "CPU table is not sorted");
 259   }
 260   for (size_t i = 1; i < FeatureTableSize; i++) {
 261     assert(strcmp(FeatureTable[i - 1].Key, FeatureTable[i].Key) < 0 &&
 262           "CPU features table is not sorted");
 263   }
 264 #endif
 265   uint32_t Bits = 0;                    // Resulting bits
 266
 267   // Check if help is needed
 268   if (Features[0] == "help")
 269     Help(CPUTable, CPUTableSize, FeatureTable, FeatureTableSize);
 270
 271   // Find CPU entry
 272   const SubtargetFeatureKV *CPUEntry =
 273                             Find(Features[0], CPUTable, CPUTableSize);
 274   // If there is a match
 275   if (CPUEntry) {
 276     // Set base feature bits
 277     Bits = CPUEntry->Value;
 278
 279     // Set the feature implied by this CPU feature, if any.
 280     for (size_t i = 0; i < FeatureTableSize; ++i) {
 281       const SubtargetFeatureKV &FE = FeatureTable[i];
 282       if (CPUEntry->Value & FE.Value)
 283         SetImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
 284     }
 285   } else {
 286     errs() << "'" << Features[0]
 287            << "' is not a recognized processor for this target"
 288            << " (ignoring processor)\n";
 289   }
 290   // Iterate through each feature
 291   for (size_t i = 1; i < Features.size(); i++) {
 292     const std::string &Feature = Features[i];
 293
 294     // Check for help
 295     if (Feature == "+help")
 296       Help(CPUTable, CPUTableSize, FeatureTable, FeatureTableSize);
 297
 298     // Find feature in table.
 299     const SubtargetFeatureKV *FeatureEntry =
 300                        Find(StripFlag(Feature), FeatureTable, FeatureTableSize);
 301     // If there is a match
 302     if (FeatureEntry) {
 303       // Enable/disable feature in bits
 304       if (isEnabled(Feature)) {
 305         Bits |=  FeatureEntry->Value;
 306
 307         // For each feature that this implies, set it.
 308         SetImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
 309       } else {
 310         Bits &= ~FeatureEntry->Value;
 311
 312         // For each feature that implies this, clear it.
 313         ClearImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
 314       }
 315     } else {
 316       errs() << "'" << Feature
 317              << "' is not a recognized feature for this target"
 318              << " (ignoring feature)\n";
 319     }
 320   }
 321
 322   return Bits;
 323 }
 324
 325 /// Get info pointer
 326 void *SubtargetFeatures::getInfo(const SubtargetInfoKV *Table,
 327                                        size_t TableSize) {
 328   assert(Table && "missing table");
 329 #ifndef NDEBUG
 330   for (size_t i = 1; i < TableSize; i++) {
 331     assert(strcmp(Table[i - 1].Key, Table[i].Key) < 0 && "Table is not sorted");
 332   }
 333 #endif
 334
 335   // Find entry
 336   const SubtargetInfoKV *Entry = Find(Features[0], Table, TableSize);
 337
 338   if (Entry) {
 339     return Entry->Value;
 340   } else {
 341     errs() << "'" << Features[0]
 342            << "' is not a recognized processor for this target"
 343            << " (ignoring processor)\n";
 344     return NULL;
 345   }
 346 }
 347
 348 /// print - Print feature string.
 349 ///
 350 void SubtargetFeatures::print(raw_ostream &OS) const {
 351   for (size_t i = 0, e = Features.size(); i != e; ++i)
 352     OS << Features[i] << "  ";
 353   OS << "\n";
 354 }
 355
 356 /// dump - Dump feature info.
 357 ///
 358 void SubtargetFeatures::dump() const {
 359   print(dbgs());
 360 }
 361
 362 /// getDefaultSubtargetFeatures - Return a string listing the features
 363 /// associated with the target triple.
 364 ///
 365 /// FIXME: This is an inelegant way of specifying the features of a
 366 /// subtarget. It would be better if we could encode this information
 367 /// into the IR. See <rdar://5972456>.
 368 ///
 369 void SubtargetFeatures::getDefaultSubtargetFeatures(const std::string &CPU,
 370                                                     const Triple& Triple) {
 371   setCPU(CPU);
 372
 373   if (Triple.getVendor() == Triple::Apple) {
 374     if (Triple.getArch() == Triple::ppc) {
 375       // powerpc-apple-*
 376       AddFeature("altivec");
 377     } else if (Triple.getArch() == Triple::ppc64) {
 378       // powerpc64-apple-*
 379       AddFeature("64bit");
 380       AddFeature("altivec");
 381     }
 382   }
 383 }