LLVM API Documentation

SubtargetFeature.cpp

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00001 //===- SubtargetFeature.cpp - CPU characteristics Implementation ----------===//
00002 //
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by James M. Laskey and is distributed under the 
00006 // University of Illinois Open Source License. See LICENSE.TXT for details.
00007 //
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file implements the SubtargetFeature interface.
00011 //
00012 //===----------------------------------------------------------------------===//
00013 
00014 #include "llvm/Target/SubtargetFeature.h"
00015 #include "llvm/ADT/StringExtras.h"
00016 #include <algorithm>
00017 #include <cassert>
00018 #include <cctype>
00019 #include <iostream>
00020 using namespace llvm;
00021 
00022 //===----------------------------------------------------------------------===//
00023 //                          Static Helper Functions
00024 //===----------------------------------------------------------------------===//
00025 
00026 /// hasFlag - Determine if a feature has a flag; '+' or '-'
00027 ///
00028 static inline bool hasFlag(const std::string &Feature) {
00029   assert(!Feature.empty() && "Empty string");
00030   // Get first character
00031   char Ch = Feature[0];
00032   // Check if first character is '+' or '-' flag
00033   return Ch == '+' || Ch =='-';
00034 }
00035 
00036 /// StripFlag - Return string stripped of flag.
00037 ///
00038 static inline std::string StripFlag(const std::string &Feature) {
00039   return hasFlag(Feature) ? Feature.substr(1) : Feature;
00040 }
00041 
00042 /// isEnabled - Return true if enable flag; '+'.
00043 ///
00044 static inline bool isEnabled(const std::string &Feature) {
00045   assert(!Feature.empty() && "Empty string");
00046   // Get first character
00047   char Ch = Feature[0];
00048   // Check if first character is '+' for enabled
00049   return Ch == '+';
00050 }
00051 
00052 /// PrependFlag - Return a string with a prepended flag; '+' or '-'.
00053 ///
00054 static inline std::string PrependFlag(const std::string &Feature,
00055                                       bool IsEnabled) {
00056   assert(!Feature.empty() && "Empty string");
00057   if (hasFlag(Feature)) return Feature;
00058   return std::string(IsEnabled ? "+" : "-") + Feature;
00059 }
00060 
00061 /// Split - Splits a string of comma separated items in to a vector of strings.
00062 ///
00063 static void Split(std::vector<std::string> &V, const std::string &S) {
00064   // Start at beginning of string.
00065   size_t Pos = 0;
00066   while (true) {
00067     // Find the next comma
00068     size_t Comma = S.find(',', Pos);
00069     // If no comma found then the the rest of the string is used
00070     if (Comma == std::string::npos) {
00071       // Add string to vector
00072       V.push_back(S.substr(Pos));
00073       break;
00074     }
00075     // Otherwise add substring to vector
00076     V.push_back(S.substr(Pos, Comma - Pos));
00077     // Advance to next item
00078     Pos = Comma + 1;
00079   }
00080 }
00081 
00082 /// Join a vector of strings to a string with a comma separating each element.
00083 ///
00084 static std::string Join(const std::vector<std::string> &V) {
00085   // Start with empty string.
00086   std::string Result;
00087   // If the vector is not empty 
00088   if (!V.empty()) {
00089     // Start with the CPU feature
00090     Result = V[0];
00091     // For each successive feature
00092     for (size_t i = 1; i < V.size(); i++) {
00093       // Add a comma
00094       Result += ",";
00095       // Add the feature
00096       Result += V[i];
00097     }
00098   }
00099   // Return the features string 
00100   return Result;
00101 }
00102 
00103 /// Adding features.
00104 void SubtargetFeatures::AddFeature(const std::string &String,
00105                                    bool IsEnabled) {
00106   // Don't add empty features
00107   if (!String.empty()) {
00108     // Convert to lowercase, prepend flag and add to vector
00109     Features.push_back(PrependFlag(LowercaseString(String), IsEnabled));
00110   }
00111 }
00112 
00113 /// Find KV in array using binary search.
00114 template<typename T> const T *Find(const std::string &S, const T *A, size_t L) {
00115   // Make the lower bound element we're looking for
00116   T KV;
00117   KV.Key = S.c_str();
00118   // Determine the end of the array
00119   const T *Hi = A + L;
00120   // Binary search the array
00121   const T *F = std::lower_bound(A, Hi, KV);
00122   // If not found then return NULL
00123   if (F == Hi || std::string(F->Key) != S) return NULL;
00124   // Return the found array item
00125   return F;
00126 }
00127 
00128 /// getLongestEntryLength - Return the length of the longest entry in the table.
00129 ///
00130 static size_t getLongestEntryLength(const SubtargetFeatureKV *Table,
00131                                     size_t Size) {
00132   size_t MaxLen = 0;
00133   for (size_t i = 0; i < Size; i++)
00134     MaxLen = std::max(MaxLen, std::strlen(Table[i].Key));
00135   return MaxLen;
00136 }
00137 
00138 /// Display help for feature choices.
00139 ///
00140 static void Help(const SubtargetFeatureKV *CPUTable, size_t CPUTableSize,
00141                  const SubtargetFeatureKV *FeatTable, size_t FeatTableSize) {
00142   // Determine the length of the longest CPU and Feature entries.
00143   unsigned MaxCPULen  = getLongestEntryLength(CPUTable, CPUTableSize);
00144   unsigned MaxFeatLen = getLongestEntryLength(FeatTable, FeatTableSize);
00145 
00146   // Print the CPU table.
00147   std::cerr << "Available CPUs for this target:\n\n";
00148   for (size_t i = 0; i != CPUTableSize; i++)
00149     std::cerr << "  " << CPUTable[i].Key
00150               << std::string(MaxCPULen - std::strlen(CPUTable[i].Key), ' ')
00151               << " - " << CPUTable[i].Desc << ".\n";
00152   std::cerr << "\n";
00153   
00154   // Print the Feature table.
00155   std::cerr << "Available features for this target:\n\n";
00156   for (size_t i = 0; i != FeatTableSize; i++)
00157     std::cerr << "  " << FeatTable[i].Key
00158       << std::string(MaxFeatLen - std::strlen(FeatTable[i].Key), ' ')
00159       << " - " << FeatTable[i].Desc << ".\n";
00160   std::cerr << "\n";
00161   
00162   std::cerr << "Use +feature to enable a feature, or -feature to disable it.\n"
00163             << "For example, llc -mcpu=mycpu -mattr=+feature1,-feature2\n";
00164   exit(1);
00165 }
00166 
00167 //===----------------------------------------------------------------------===//
00168 //                    SubtargetFeatures Implementation
00169 //===----------------------------------------------------------------------===//
00170 
00171 SubtargetFeatures::SubtargetFeatures(const std::string &Initial) {
00172   // Break up string into separate features
00173   Split(Features, Initial);
00174 }
00175 
00176 
00177 std::string SubtargetFeatures::getString() const {
00178   return Join(Features);
00179 }
00180 void SubtargetFeatures::setString(const std::string &Initial) {
00181   // Throw out old features
00182   Features.clear();
00183   // Break up string into separate features
00184   Split(Features, LowercaseString(Initial));
00185 }
00186 
00187 
00188 /// setCPU - Set the CPU string.  Replaces previous setting.  Setting to "" 
00189 /// clears CPU.
00190 void SubtargetFeatures::setCPU(const std::string &String) {
00191   Features[0] = LowercaseString(String);
00192 }
00193 
00194 
00195 /// setCPUIfNone - Setting CPU string only if no string is set.
00196 ///
00197 void SubtargetFeatures::setCPUIfNone(const std::string &String) {
00198   if (Features[0].empty()) setCPU(String);
00199 }
00200 
00201 
00202 /// getBits - Get feature bits.
00203 ///
00204 uint32_t SubtargetFeatures::getBits(const SubtargetFeatureKV *CPUTable,
00205                                           size_t CPUTableSize,
00206                                     const SubtargetFeatureKV *FeatureTable,
00207                                           size_t FeatureTableSize) {
00208   assert(CPUTable && "missing CPU table");
00209   assert(FeatureTable && "missing features table");
00210 #ifndef NDEBUG
00211   for (size_t i = 1; i < CPUTableSize; i++) {
00212     assert(strcmp(CPUTable[i - 1].Key, CPUTable[i].Key) < 0 &&
00213            "CPU table is not sorted");
00214   }
00215   for (size_t i = 1; i < FeatureTableSize; i++) {
00216     assert(strcmp(FeatureTable[i - 1].Key, FeatureTable[i].Key) < 0 &&
00217           "CPU features table is not sorted");
00218   }
00219 #endif
00220   uint32_t Bits = 0;                    // Resulting bits
00221 
00222   // Check if help is needed
00223   if (Features[0] == "help")
00224     Help(CPUTable, CPUTableSize, FeatureTable, FeatureTableSize);
00225   
00226   // Find CPU entry
00227   const SubtargetFeatureKV *CPUEntry =
00228                             Find(Features[0], CPUTable, CPUTableSize);
00229   // If there is a match
00230   if (CPUEntry) {
00231     // Set base feature bits
00232     Bits = CPUEntry->Value;
00233   } else {
00234     std::cerr << "'" << Features[0]
00235               << "' is not a recognized processor for this target"
00236               << " (ignoring processor)"
00237               << "\n";
00238   }
00239   // Iterate through each feature
00240   for (size_t i = 1; i < Features.size(); i++) {
00241     const std::string &Feature = Features[i];
00242     
00243     // Check for help
00244     if (Feature == "+help")
00245       Help(CPUTable, CPUTableSize, FeatureTable, FeatureTableSize);
00246     
00247     // Find feature in table.
00248     const SubtargetFeatureKV *FeatureEntry =
00249                        Find(StripFlag(Feature), FeatureTable, FeatureTableSize);
00250     // If there is a match
00251     if (FeatureEntry) {
00252       // Enable/disable feature in bits
00253       if (isEnabled(Feature)) Bits |=  FeatureEntry->Value;
00254       else                    Bits &= ~FeatureEntry->Value;
00255     } else {
00256       std::cerr << "'" << Feature
00257                 << "' is not a recognized feature for this target"
00258                 << " (ignoring feature)"
00259                 << "\n";
00260     }
00261   }
00262   return Bits;
00263 }
00264 
00265 /// Get info pointer
00266 void *SubtargetFeatures::getInfo(const SubtargetInfoKV *Table,
00267                                        size_t TableSize) {
00268   assert(Table && "missing table");
00269 #ifndef NDEBUG
00270   for (size_t i = 1; i < TableSize; i++) {
00271     assert(strcmp(Table[i - 1].Key, Table[i].Key) < 0 && "Table is not sorted");
00272   }
00273 #endif
00274 
00275   // Find entry
00276   const SubtargetInfoKV *Entry = Find(Features[0], Table, TableSize);
00277   
00278   if (Entry) {
00279     return Entry->Value;
00280   } else {
00281     std::cerr << "'" << Features[0]
00282               << "' is not a recognized processor for this target"
00283               << " (ignoring processor)"
00284               << "\n";
00285     return NULL;
00286   }
00287 }
00288 
00289 /// print - Print feature string.
00290 ///
00291 void SubtargetFeatures::print(std::ostream &OS) const {
00292   for (size_t i = 0; i < Features.size(); i++) {
00293     OS << Features[i] << "  ";
00294   }
00295   OS << "\n";
00296 }
00297 
00298 /// dump - Dump feature info.
00299 ///
00300 void SubtargetFeatures::dump() const {
00301   print(std::cerr);
00302 }