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 #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 std::string &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 std::string &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 std::string &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 /// PrependFlag - Return a string with a prepended flag; '+' or '-'.
  55 ///
  56 static inline std::string PrependFlag(const std::string &Feature,
  57                                       bool IsEnabled) {
  58   assert(!Feature.empty() && "Empty string");
  59   if (hasFlag(Feature)) return Feature;
  60   return std::string(IsEnabled ? "+" : "-") + Feature;
  61 }
  62
  63 /// Split - Splits a string of comma separated items in to a vector of strings.
  64 ///
  65 static void Split(std::vector<std::string> &V, const std::string &S) {
  66   // Start at beginning of string.
  67   size_t Pos = 0;
  68   while (true) {
  69     // Find the next comma
  70     size_t Comma = S.find(',', Pos);
  71     // If no comma found then the rest of the string is used
  72     if (Comma == std::string::npos) {
  73       // Add string to vector
  74       V.push_back(S.substr(Pos));
  75       break;
  76     }
  77     // Otherwise add substring to vector
  78     V.push_back(S.substr(Pos, Comma - Pos));
  79     // Advance to next item
  80     Pos = Comma + 1;
  81   }
  82 }
  83
  84 /// Join a vector of strings to a string with a comma separating each element.
  85 ///
  86 static std::string Join(const std::vector<std::string> &V) {
  87   // Start with empty string.
  88   std::string Result;
  89   // If the vector is not empty
  90   if (!V.empty()) {
  91     // Start with the CPU feature
  92     Result = V[0];
  93     // For each successive feature
  94     for (size_t i = 1; i < V.size(); i++) {
  95       // Add a comma
  96       Result += ",";
  97       // Add the feature
  98       Result += V[i];
  99     }
 100   }
 101   // Return the features string
 102   return Result;
 103 }
 104
 105 /// Adding features.
 106 void SubtargetFeatures::AddFeature(const std::string &String,
 107                                    bool IsEnabled) {
 108   // Don't add empty features
 109   if (!String.empty()) {
 110     // Convert to lowercase, prepend flag and add to vector
 111     Features.push_back(PrependFlag(LowercaseString(String), IsEnabled));
 112   }
 113 }
 114
 115 /// Find KV in array using binary search.
 116 template<typename T> const T *Find(const std::string &S, const T *A, size_t L) {
 117   // Make the lower bound element we're looking for
 118   T KV;
 119   KV.Key = S.c_str();
 120   // Determine the end of the array
 121   const T *Hi = A + L;
 122   // Binary search the array
 123   const T *F = std::lower_bound(A, Hi, KV);
 124   // If not found then return NULL
 125   if (F == Hi || std::string(F->Key) != S) return NULL;
 126   // Return the found array item
 127   return F;
 128 }
 129
 130 /// getLongestEntryLength - Return the length of the longest entry in the table.
 131 ///
 132 static size_t getLongestEntryLength(const SubtargetFeatureKV *Table,
 133                                     size_t Size) {
 134   size_t MaxLen = 0;
 135   for (size_t i = 0; i < Size; i++)
 136     MaxLen = std::max(MaxLen, std::strlen(Table[i].Key));
 137   return MaxLen;
 138 }
 139
 140 /// Display help for feature choices.
 141 ///
 142 static void Help(const SubtargetFeatureKV *CPUTable, size_t CPUTableSize,
 143                  const SubtargetFeatureKV *FeatTable, size_t FeatTableSize) {
 144   // Determine the length of the longest CPU and Feature entries.
 145   unsigned MaxCPULen  = getLongestEntryLength(CPUTable, CPUTableSize);
 146   unsigned MaxFeatLen = getLongestEntryLength(FeatTable, FeatTableSize);
 147
 148   // Print the CPU table.
 149   errs() << "Available CPUs for this target:\n\n";
 150   for (size_t i = 0; i != CPUTableSize; i++)
 151     errs() << "  " << CPUTable[i].Key
 152          << std::string(MaxCPULen - std::strlen(CPUTable[i].Key), ' ')
 153          << " - " << CPUTable[i].Desc << ".\n";
 154   errs() << "\n";
 155
 156   // Print the Feature table.
 157   errs() << "Available features for this target:\n\n";
 158   for (size_t i = 0; i != FeatTableSize; i++)
 159     errs() << "  " << FeatTable[i].Key
 160          << std::string(MaxFeatLen - std::strlen(FeatTable[i].Key), ' ')
 161          << " - " << FeatTable[i].Desc << ".\n";
 162   errs() << "\n";
 163
 164   errs() << "Use +feature to enable a feature, or -feature to disable it.\n"
 165        << "For example, llc -mcpu=mycpu -mattr=+feature1,-feature2\n";
 166   std::exit(1);
 167 }
 168
 169 //===----------------------------------------------------------------------===//
 170 //                    SubtargetFeatures Implementation
 171 //===----------------------------------------------------------------------===//
 172
 173 SubtargetFeatures::SubtargetFeatures(const std::string &Initial) {
 174   // Break up string into separate features
 175   Split(Features, Initial);
 176 }
 177
 178
 179 std::string SubtargetFeatures::getString() const {
 180   return Join(Features);
 181 }
 182 void SubtargetFeatures::setString(const std::string &Initial) {
 183   // Throw out old features
 184   Features.clear();
 185   // Break up string into separate features
 186   Split(Features, LowercaseString(Initial));
 187 }
 188
 189
 190 /// setCPU - Set the CPU string.  Replaces previous setting.  Setting to ""
 191 /// clears CPU.
 192 void SubtargetFeatures::setCPU(const std::string &String) {
 193   Features[0] = LowercaseString(String);
 194 }
 195
 196
 197 /// setCPUIfNone - Setting CPU string only if no string is set.
 198 ///
 199 void SubtargetFeatures::setCPUIfNone(const std::string &String) {
 200   if (Features[0].empty()) setCPU(String);
 201 }
 202
 203 /// getCPU - Returns current CPU.
 204 ///
 205 const std::string & SubtargetFeatures::getCPU() const {
 206   return Features[0];
 207 }
 208
 209
 210 /// SetImpliedBits - For each feature that is (transitively) implied by this
 211 /// feature, set it.
 212 ///
 213 static
 214 void SetImpliedBits(uint32_t &Bits, const SubtargetFeatureKV *FeatureEntry,
 215                     const SubtargetFeatureKV *FeatureTable,
 216                     size_t FeatureTableSize) {
 217   for (size_t i = 0; i < FeatureTableSize; ++i) {
 218     const SubtargetFeatureKV &FE = FeatureTable[i];
 219
 220     if (FeatureEntry->Value == FE.Value) continue;
 221
 222     if (FeatureEntry->Implies & FE.Value) {
 223       Bits |= FE.Value;
 224       SetImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
 225     }
 226   }
 227 }
 228
 229 /// ClearImpliedBits - For each feature that (transitively) implies this
 230 /// feature, clear it.
 231 ///
 232 static
 233 void ClearImpliedBits(uint32_t &Bits, const SubtargetFeatureKV *FeatureEntry,
 234                       const SubtargetFeatureKV *FeatureTable,
 235                       size_t FeatureTableSize) {
 236   for (size_t i = 0; i < FeatureTableSize; ++i) {
 237     const SubtargetFeatureKV &FE = FeatureTable[i];
 238
 239     if (FeatureEntry->Value == FE.Value) continue;
 240
 241     if (FE.Implies & FeatureEntry->Value) {
 242       Bits &= ~FE.Value;
 243       ClearImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
 244     }
 245   }
 246 }
 247
 248 /// getBits - Get feature bits.
 249 ///
 250 uint32_t SubtargetFeatures::getBits(const SubtargetFeatureKV *CPUTable,
 251                                           size_t CPUTableSize,
 252                                     const SubtargetFeatureKV *FeatureTable,
 253                                           size_t FeatureTableSize) {
 254   assert(CPUTable && "missing CPU table");
 255   assert(FeatureTable && "missing features table");
 256 #ifndef NDEBUG
 257   for (size_t i = 1; i < CPUTableSize; i++) {
 258     assert(strcmp(CPUTable[i - 1].Key, CPUTable[i].Key) < 0 &&
 259            "CPU table is not sorted");
 260   }
 261   for (size_t i = 1; i < FeatureTableSize; i++) {
 262     assert(strcmp(FeatureTable[i - 1].Key, FeatureTable[i].Key) < 0 &&
 263           "CPU features table is not sorted");
 264   }
 265 #endif
 266   uint32_t Bits = 0;                    // Resulting bits
 267
 268   // Check if help is needed
 269   if (Features[0] == "help")
 270     Help(CPUTable, CPUTableSize, FeatureTable, FeatureTableSize);
 271
 272   // Find CPU entry
 273   const SubtargetFeatureKV *CPUEntry =
 274                             Find(Features[0], CPUTable, CPUTableSize);
 275   // If there is a match
 276   if (CPUEntry) {
 277     // Set base feature bits
 278     Bits = CPUEntry->Value;
 279
 280     // Set the feature implied by this CPU feature, if any.
 281     for (size_t i = 0; i < FeatureTableSize; ++i) {
 282       const SubtargetFeatureKV &FE = FeatureTable[i];
 283       if (CPUEntry->Value & FE.Value)
 284         SetImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
 285     }
 286   } else {
 287     errs() << "'" << Features[0]
 288            << "' is not a recognized processor for this target"
 289            << " (ignoring processor)\n";
 290   }
 291   // Iterate through each feature
 292   for (size_t i = 1; i < Features.size(); i++) {
 293     const std::string &Feature = Features[i];
 294
 295     // Check for help
 296     if (Feature == "+help")
 297       Help(CPUTable, CPUTableSize, FeatureTable, FeatureTableSize);
 298
 299     // Find feature in table.
 300     const SubtargetFeatureKV *FeatureEntry =
 301                        Find(StripFlag(Feature), FeatureTable, FeatureTableSize);
 302     // If there is a match
 303     if (FeatureEntry) {
 304       // Enable/disable feature in bits
 305       if (isEnabled(Feature)) {
 306         Bits |=  FeatureEntry->Value;
 307
 308         // For each feature that this implies, set it.
 309         SetImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
 310       } else {
 311         Bits &= ~FeatureEntry->Value;
 312
 313         // For each feature that implies this, clear it.
 314         ClearImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
 315       }
 316     } else {
 317       errs() << "'" << Feature
 318              << "' is not a recognized feature for this target"
 319              << " (ignoring feature)\n";
 320     }
 321   }
 322
 323   return Bits;
 324 }
 325
 326 /// Get info pointer
 327 void *SubtargetFeatures::getInfo(const SubtargetInfoKV *Table,
 328                                        size_t TableSize) {
 329   assert(Table && "missing table");
 330 #ifndef NDEBUG
 331   for (size_t i = 1; i < TableSize; i++) {
 332     assert(strcmp(Table[i - 1].Key, Table[i].Key) < 0 && "Table is not sorted");
 333   }
 334 #endif
 335
 336   // Find entry
 337   const SubtargetInfoKV *Entry = Find(Features[0], Table, TableSize);
 338
 339   if (Entry) {
 340     return Entry->Value;
 341   } else {
 342     errs() << "'" << Features[0]
 343            << "' is not a recognized processor for this target"
 344            << " (ignoring processor)\n";
 345     return NULL;
 346   }
 347 }
 348
 349 /// print - Print feature string.
 350 ///
 351 void SubtargetFeatures::print(raw_ostream &OS) const {
 352   for (size_t i = 0, e = Features.size(); i != e; ++i)
 353     OS << Features[i] << "  ";
 354   OS << "\n";
 355 }
 356
 357 /// dump - Dump feature info.
 358 ///
 359 void SubtargetFeatures::dump() const {
 360   print(dbgs());
 361 }
 362
 363 /// getDefaultSubtargetFeatures - Return a string listing the features
 364 /// associated with the target triple.
 365 ///
 366 /// FIXME: This is an inelegant way of specifying the features of a
 367 /// subtarget. It would be better if we could encode this information
 368 /// into the IR. See <rdar://5972456>.
 369 ///
 370 void SubtargetFeatures::getDefaultSubtargetFeatures(const std::string &CPU,
 371                                                     const Triple& Triple) {
 372   setCPU(CPU);
 373
 374   if (Triple.getVendor() == Triple::Apple) {
 375     if (Triple.getArch() == Triple::ppc) {
 376       // powerpc-apple-*
 377       AddFeature("altivec");
 378     } else if (Triple.getArch() == Triple::ppc64) {
 379       // powerpc64-apple-*
 380       AddFeature("64bit");
 381       AddFeature("altivec");
 382     }
 383   }
 384 }