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