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> 22using namespace llvm; 23 24//===----------------------------------------------------------------------===// 25// Static Helper Functions 26//===----------------------------------------------------------------------===// 27 28/// hasFlag - Determine if a feature has a flag; '+' or '-' 29/// 30static inline bool hasFlag(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/// 40static inline std::string StripFlag(StringRef Feature) { 41 return hasFlag(Feature) ? Feature.substr(1) : Feature; 42} 43 44/// isEnabled - Return true if enable flag; '+'. 45/// 46static inline bool isEnabled(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/// 56static void Split(std::vector<std::string> &V, StringRef S) { 57 SmallVector<StringRef, 3> 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/// 64static 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. 84void SubtargetFeatures::AddFeature(StringRef String, bool Enable) { 85 // Don't add empty features. 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.lower() 89 : (Enable ? "+" : "-") + String.lower()); 90} 91 92/// Find KV in array using binary search. 93static const SubtargetFeatureKV *Find(StringRef S, 94 ArrayRef<SubtargetFeatureKV> A) { 95 // Binary search the array 96 auto F = std::lower_bound(A.begin(), A.end(), S); 97 // If not found then return NULL 98 if (F == A.end() || StringRef(F->Key) != S) return nullptr; 99 // Return the found array item 100 return F; 101} 102 103/// getLongestEntryLength - Return the length of the longest entry in the table. 104/// 105static size_t getLongestEntryLength(ArrayRef<SubtargetFeatureKV> Table) { 106 size_t MaxLen = 0; 107 for (auto &I : Table) 108 MaxLen = std::max(MaxLen, std::strlen(I.Key)); 109 return MaxLen; 110} 111 112/// Display help for feature choices. 113/// 114static void Help(ArrayRef<SubtargetFeatureKV> CPUTable, 115 ArrayRef<SubtargetFeatureKV> FeatTable) { 116 // Determine the length of the longest CPU and Feature entries. 117 unsigned MaxCPULen = getLongestEntryLength(CPUTable); 118 unsigned MaxFeatLen = getLongestEntryLength(FeatTable); 119 120 // Print the CPU table. 121 errs() << "Available CPUs for this target:\n\n"; 122 for (auto &CPU : CPUTable) 123 errs() << format(" %-*s - %s.\n", MaxCPULen, CPU.Key, CPU.Desc); 124 errs() << '\n'; 125 126 // Print the Feature table. 127 errs() << "Available features for this target:\n\n"; 128 for (auto &Feature : FeatTable) 129 errs() << format(" %-*s - %s.\n", MaxFeatLen, Feature.Key, Feature.Desc); 130 errs() << '\n'; 131 132 errs() << "Use +feature to enable a feature, or -feature to disable it.\n" 133 "For example, llc -mcpu=mycpu -mattr=+feature1,-feature2\n"; 134} 135 136//===----------------------------------------------------------------------===// 137// SubtargetFeatures Implementation 138//===----------------------------------------------------------------------===// 139 140SubtargetFeatures::SubtargetFeatures(StringRef Initial) { 141 // Break up string into separate features 142 Split(Features, Initial); 143} 144 145 146std::string SubtargetFeatures::getString() const { 147 return Join(Features); 148} 149 150/// SetImpliedBits - For each feature that is (transitively) implied by this 151/// feature, set it. 152/// 153static 154void SetImpliedBits(uint64_t &Bits, const SubtargetFeatureKV *FeatureEntry, 155 ArrayRef<SubtargetFeatureKV> FeatureTable) { 156 for (auto &FE : FeatureTable) { 157 if (FeatureEntry->Value == FE.Value) continue; 158 159 if (FeatureEntry->Implies & FE.Value) { 160 Bits |= FE.Value; 161 SetImpliedBits(Bits, &FE, FeatureTable); 162 } 163 } 164} 165 166/// ClearImpliedBits - For each feature that (transitively) implies this 167/// feature, clear it. 168/// 169static 170void ClearImpliedBits(uint64_t &Bits, const SubtargetFeatureKV *FeatureEntry, 171 ArrayRef<SubtargetFeatureKV> FeatureTable) { 172 for (auto &FE : FeatureTable) { 173 if (FeatureEntry->Value == FE.Value) continue; 174 175 if (FE.Implies & FeatureEntry->Value) { 176 Bits &= ~FE.Value; 177 ClearImpliedBits(Bits, &FE, FeatureTable); 178 } 179 } 180} 181 182/// ToggleFeature - Toggle a feature and returns the newly updated feature 183/// bits. 184uint64_t 185SubtargetFeatures::ToggleFeature(uint64_t Bits, StringRef Feature, 186 ArrayRef<SubtargetFeatureKV> FeatureTable) { 187 188 // Find feature in table. 189 const SubtargetFeatureKV *FeatureEntry = 190 Find(StripFlag(Feature), FeatureTable); 191 // If there is a match 192 if (FeatureEntry) { 193 if ((Bits & FeatureEntry->Value) == FeatureEntry->Value) { 194 Bits &= ~FeatureEntry->Value; 195 196 // For each feature that implies this, clear it. 197 ClearImpliedBits(Bits, FeatureEntry, FeatureTable); 198 } else { 199 Bits |= FeatureEntry->Value; 200 201 // For each feature that this implies, set it. 202 SetImpliedBits(Bits, FeatureEntry, FeatureTable); 203 } 204 } else { 205 // Bug: 20140355 206 // Silence this warning for now 207 if (false) { 208 errs() << "'" << Feature 209 << "' is not a recognized feature for this target" 210 << " (ignoring feature)\n"; 211 } 212 } 213 214 return Bits; 215} 216 217 218/// getFeatureBits - Get feature bits a CPU. 219/// 220uint64_t 221SubtargetFeatures::getFeatureBits(StringRef CPU, 222 ArrayRef<SubtargetFeatureKV> CPUTable, 223 ArrayRef<SubtargetFeatureKV> FeatureTable) { 224 225 if (CPUTable.empty() || FeatureTable.empty()) 226 return 0; 227 228#ifndef NDEBUG 229 for (size_t i = 1, e = CPUTable.size(); i != e; ++i) { 230 assert(strcmp(CPUTable[i - 1].Key, CPUTable[i].Key) < 0 && 231 "CPU table is not sorted"); 232 } 233 for (size_t i = 1, e = FeatureTable.size(); i != e; ++i) { 234 assert(strcmp(FeatureTable[i - 1].Key, FeatureTable[i].Key) < 0 && 235 "CPU features table is not sorted"); 236 } 237#endif 238 uint64_t Bits = 0; // Resulting bits 239 240 // Check if help is needed 241 if (CPU == "help") 242 Help(CPUTable, FeatureTable); 243 244 // Find CPU entry if CPU name is specified. 245 else if (!CPU.empty()) { 246 const SubtargetFeatureKV *CPUEntry = Find(CPU, CPUTable); 247 248 // If there is a match 249 if (CPUEntry) { 250 // Set base feature bits 251 Bits = CPUEntry->Value; 252 253 // Set the feature implied by this CPU feature, if any. 254 for (auto &FE : FeatureTable) { 255 if (CPUEntry->Value & FE.Value) 256 SetImpliedBits(Bits, &FE, FeatureTable); 257 } 258 } else { 259 errs() << "'" << CPU 260 << "' is not a recognized processor for this target" 261 << " (ignoring processor)\n"; 262 } 263 } 264 265 // Iterate through each feature 266 for (auto &Feature : Features) { 267 // Check for help 268 if (Feature == "+help") 269 Help(CPUTable, FeatureTable); 270 271 // Find feature in table. 272 const SubtargetFeatureKV *FeatureEntry = 273 Find(StripFlag(Feature), FeatureTable); 274 // If there is a match 275 if (FeatureEntry) { 276 // Enable/disable feature in bits 277 if (isEnabled(Feature)) { 278 Bits |= FeatureEntry->Value; 279 280 // For each feature that this implies, set it. 281 SetImpliedBits(Bits, FeatureEntry, FeatureTable); 282 } else { 283 Bits &= ~FeatureEntry->Value; 284 285 // For each feature that implies this, clear it. 286 ClearImpliedBits(Bits, FeatureEntry, FeatureTable); 287 } 288 } else { 289 // Bug: 20140355 290 // Silence this warning for now 291 if (false) { 292 errs() << "'" << Feature 293 << "' is not a recognized feature for this target" 294 << " (ignoring feature)\n"; 295 } 296 } 297 } 298 299 return Bits; 300} 301 302/// print - Print feature string. 303/// 304void SubtargetFeatures::print(raw_ostream &OS) const { 305 for (auto &F : Features) 306 OS << F << " "; 307 OS << "\n"; 308} 309 310#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 311/// dump - Dump feature info. 312/// 313void SubtargetFeatures::dump() const { 314 print(dbgs()); 315} 316#endif 317 318/// Adds the default features for the specified target triple. 319/// 320/// FIXME: This is an inelegant way of specifying the features of a 321/// subtarget. It would be better if we could encode this information 322/// into the IR. See <rdar://5972456>. 323/// 324void SubtargetFeatures::getDefaultSubtargetFeatures(const Triple& Triple) { 325 if (Triple.getVendor() == Triple::Apple) { 326 if (Triple.getArch() == Triple::ppc) { 327 // powerpc-apple-* 328 AddFeature("altivec"); 329 } else if (Triple.getArch() == Triple::ppc64) { 330 // powerpc64-apple-* 331 AddFeature("64bit"); 332 AddFeature("altivec"); 333 } 334 } 335} 336