lib/MC/MCSubtargetInfo.cpp

   1 //===- MCSubtargetInfo.cpp - Subtarget Information ------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/MC/MCSubtargetInfo.h"
  10 #include "llvm/ADT/ArrayRef.h"
  11 #include "llvm/ADT/StringRef.h"
  12 #include "llvm/MC/MCInstrItineraries.h"
  13 #include "llvm/MC/MCSchedule.h"
  14 #include "llvm/MC/SubtargetFeature.h"
  15 #include "llvm/Support/Format.h"
  16 #include "llvm/Support/raw_ostream.h"
  17 #include <algorithm>
  18 #include <cassert>
  19 #include <cstring>
  20
  21 using namespace llvm;
  22
  23 /// Find KV in array using binary search.
  24 template <typename T>
  25 static const T *Find(StringRef S, ArrayRef<T> A) {
  26   // Binary search the array
  27   auto F = llvm::lower_bound(A, S);
  28   // If not found then return NULL
  29   if (F == A.end() || StringRef(F->Key) != S) return nullptr;
  30   // Return the found array item
  31   return F;
  32 }
  33
  34 /// For each feature that is (transitively) implied by this feature, set it.
  35 static
  36 void SetImpliedBits(FeatureBitset &Bits, const FeatureBitset &Implies,
  37                     ArrayRef<SubtargetFeatureKV> FeatureTable) {
  38   // OR the Implies bits in outside the loop. This allows the Implies for CPUs
  39   // which might imply features not in FeatureTable to use this.
  40   Bits |= Implies;
  41   for (const SubtargetFeatureKV &FE : FeatureTable)
  42     if (Implies.test(FE.Value))
  43       SetImpliedBits(Bits, FE.Implies.getAsBitset(), FeatureTable);
  44 }
  45
  46 /// For each feature that (transitively) implies this feature, clear it.
  47 static
  48 void ClearImpliedBits(FeatureBitset &Bits, unsigned Value,
  49                       ArrayRef<SubtargetFeatureKV> FeatureTable) {
  50   for (const SubtargetFeatureKV &FE : FeatureTable) {
  51     if (FE.Implies.getAsBitset().test(Value)) {
  52       Bits.reset(FE.Value);
  53       ClearImpliedBits(Bits, FE.Value, FeatureTable);
  54     }
  55   }
  56 }
  57
  58 static void ApplyFeatureFlag(FeatureBitset &Bits, StringRef Feature,
  59                              ArrayRef<SubtargetFeatureKV> FeatureTable) {
  60   assert(SubtargetFeatures::hasFlag(Feature) &&
  61          "Feature flags should start with '+' or '-'");
  62
  63   // Find feature in table.
  64   const SubtargetFeatureKV *FeatureEntry =
  65       Find(SubtargetFeatures::StripFlag(Feature), FeatureTable);
  66   // If there is a match
  67   if (FeatureEntry) {
  68     // Enable/disable feature in bits
  69     if (SubtargetFeatures::isEnabled(Feature)) {
  70       Bits.set(FeatureEntry->Value);
  71
  72       // For each feature that this implies, set it.
  73       SetImpliedBits(Bits, FeatureEntry->Implies.getAsBitset(), FeatureTable);
  74     } else {
  75       Bits.reset(FeatureEntry->Value);
  76
  77       // For each feature that implies this, clear it.
  78       ClearImpliedBits(Bits, FeatureEntry->Value, FeatureTable);
  79     }
  80   } else {
  81     errs() << "'" << Feature << "' is not a recognized feature for this target"
  82            << " (ignoring feature)\n";
  83   }
  84 }
  85
  86 /// Return the length of the longest entry in the table.
  87 template <typename T>
  88 static size_t getLongestEntryLength(ArrayRef<T> Table) {
  89   size_t MaxLen = 0;
  90   for (auto &I : Table)
  91     MaxLen = std::max(MaxLen, std::strlen(I.Key));
  92   return MaxLen;
  93 }
  94
  95 /// Display help for feature and mcpu choices.
  96 static void Help(ArrayRef<SubtargetSubTypeKV> CPUTable,
  97                  ArrayRef<SubtargetFeatureKV> FeatTable) {
  98   // the static variable ensures that the help information only gets
  99   // printed once even though a target machine creates multiple subtargets
 100   static bool PrintOnce = false;
 101   if (PrintOnce) {
 102     return;
 103   }
 104
 105   // Determine the length of the longest CPU and Feature entries.
 106   unsigned MaxCPULen  = getLongestEntryLength(CPUTable);
 107   unsigned MaxFeatLen = getLongestEntryLength(FeatTable);
 108
 109   // Print the CPU table.
 110   errs() << "Available CPUs for this target:\n\n";
 111   for (auto &CPU : CPUTable)
 112     errs() << format("  %-*s - Select the %s processor.\n", MaxCPULen, CPU.Key,
 113                      CPU.Key);
 114   errs() << '\n';
 115
 116   // Print the Feature table.
 117   errs() << "Available features for this target:\n\n";
 118   for (auto &Feature : FeatTable)
 119     errs() << format("  %-*s - %s.\n", MaxFeatLen, Feature.Key, Feature.Desc);
 120   errs() << '\n';
 121
 122   errs() << "Use +feature to enable a feature, or -feature to disable it.\n"
 123             "For example, llc -mcpu=mycpu -mattr=+feature1,-feature2\n";
 124
 125   PrintOnce = true;
 126 }
 127
 128 /// Display help for mcpu choices only
 129 static void cpuHelp(ArrayRef<SubtargetSubTypeKV> CPUTable) {
 130   // the static variable ensures that the help information only gets
 131   // printed once even though a target machine creates multiple subtargets
 132   static bool PrintOnce = false;
 133   if (PrintOnce) {
 134     return;
 135   }
 136
 137   // Print the CPU table.
 138   errs() << "Available CPUs for this target:\n\n";
 139   for (auto &CPU : CPUTable)
 140     errs() << "\t" << CPU.Key << "\n";
 141   errs() << '\n';
 142
 143   errs() << "Use -mcpu or -mtune to specify the target's processor.\n"
 144             "For example, clang --target=aarch64-unknown-linux-gui "
 145             "-mcpu=cortex-a35\n";
 146
 147   PrintOnce = true;
 148 }
 149
 150 static FeatureBitset getFeatures(StringRef CPU, StringRef FS,
 151                                  ArrayRef<SubtargetSubTypeKV> ProcDesc,
 152                                  ArrayRef<SubtargetFeatureKV> ProcFeatures) {
 153   SubtargetFeatures Features(FS);
 154
 155   if (ProcDesc.empty() || ProcFeatures.empty())
 156     return FeatureBitset();
 157
 158   assert(std::is_sorted(std::begin(ProcDesc), std::end(ProcDesc)) &&
 159          "CPU table is not sorted");
 160   assert(std::is_sorted(std::begin(ProcFeatures), std::end(ProcFeatures)) &&
 161          "CPU features table is not sorted");
 162   // Resulting bits
 163   FeatureBitset Bits;
 164
 165   // Check if help is needed
 166   if (CPU == "help")
 167     Help(ProcDesc, ProcFeatures);
 168
 169   // Find CPU entry if CPU name is specified.
 170   else if (!CPU.empty()) {
 171     const SubtargetSubTypeKV *CPUEntry = Find(CPU, ProcDesc);
 172
 173     // If there is a match
 174     if (CPUEntry) {
 175       // Set the features implied by this CPU feature, if any.
 176       SetImpliedBits(Bits, CPUEntry->Implies.getAsBitset(), ProcFeatures);
 177     } else {
 178       errs() << "'" << CPU << "' is not a recognized processor for this target"
 179              << " (ignoring processor)\n";
 180     }
 181   }
 182
 183   // Iterate through each feature
 184   for (const std::string &Feature : Features.getFeatures()) {
 185     // Check for help
 186     if (Feature == "+help")
 187       Help(ProcDesc, ProcFeatures);
 188     else if (Feature == "+cpuHelp")
 189       cpuHelp(ProcDesc);
 190     else
 191       ApplyFeatureFlag(Bits, Feature, ProcFeatures);
 192   }
 193
 194   return Bits;
 195 }
 196
 197 void MCSubtargetInfo::InitMCProcessorInfo(StringRef CPU, StringRef FS) {
 198   FeatureBits = getFeatures(CPU, FS, ProcDesc, ProcFeatures);
 199   if (!CPU.empty())
 200     CPUSchedModel = &getSchedModelForCPU(CPU);
 201   else
 202     CPUSchedModel = &MCSchedModel::GetDefaultSchedModel();
 203 }
 204
 205 void MCSubtargetInfo::setDefaultFeatures(StringRef CPU, StringRef FS) {
 206   FeatureBits = getFeatures(CPU, FS, ProcDesc, ProcFeatures);
 207 }
 208
 209 MCSubtargetInfo::MCSubtargetInfo(
 210     const Triple &TT, StringRef C, StringRef FS,
 211     ArrayRef<SubtargetFeatureKV> PF, ArrayRef<SubtargetSubTypeKV> PD,
 212     const MCWriteProcResEntry *WPR,
 213     const MCWriteLatencyEntry *WL, const MCReadAdvanceEntry *RA,
 214     const InstrStage *IS, const unsigned *OC, const unsigned *FP)
 215     : TargetTriple(TT), CPU(C), ProcFeatures(PF), ProcDesc(PD),
 216       WriteProcResTable(WPR), WriteLatencyTable(WL),
 217       ReadAdvanceTable(RA), Stages(IS), OperandCycles(OC), ForwardingPaths(FP) {
 218   InitMCProcessorInfo(CPU, FS);
 219 }
 220
 221 FeatureBitset MCSubtargetInfo::ToggleFeature(uint64_t FB) {
 222   FeatureBits.flip(FB);
 223   return FeatureBits;
 224 }
 225
 226 FeatureBitset MCSubtargetInfo::ToggleFeature(const FeatureBitset &FB) {
 227   FeatureBits ^= FB;
 228   return FeatureBits;
 229 }
 230
 231 FeatureBitset MCSubtargetInfo::SetFeatureBitsTransitively(
 232   const FeatureBitset &FB) {
 233   SetImpliedBits(FeatureBits, FB, ProcFeatures);
 234   return FeatureBits;
 235 }
 236
 237 FeatureBitset MCSubtargetInfo::ClearFeatureBitsTransitively(
 238   const FeatureBitset &FB) {
 239   for (unsigned I = 0, E = FB.size(); I < E; I++) {
 240     if (FB[I]) {
 241       FeatureBits.reset(I);
 242       ClearImpliedBits(FeatureBits, I, ProcFeatures);
 243     }
 244   }
 245   return FeatureBits;
 246 }
 247
 248 FeatureBitset MCSubtargetInfo::ToggleFeature(StringRef Feature) {
 249   // Find feature in table.
 250   const SubtargetFeatureKV *FeatureEntry =
 251       Find(SubtargetFeatures::StripFlag(Feature), ProcFeatures);
 252   // If there is a match
 253   if (FeatureEntry) {
 254     if (FeatureBits.test(FeatureEntry->Value)) {
 255       FeatureBits.reset(FeatureEntry->Value);
 256       // For each feature that implies this, clear it.
 257       ClearImpliedBits(FeatureBits, FeatureEntry->Value, ProcFeatures);
 258     } else {
 259       FeatureBits.set(FeatureEntry->Value);
 260
 261       // For each feature that this implies, set it.
 262       SetImpliedBits(FeatureBits, FeatureEntry->Implies.getAsBitset(),
 263                      ProcFeatures);
 264     }
 265   } else {
 266     errs() << "'" << Feature << "' is not a recognized feature for this target"
 267            << " (ignoring feature)\n";
 268   }
 269
 270   return FeatureBits;
 271 }
 272
 273 FeatureBitset MCSubtargetInfo::ApplyFeatureFlag(StringRef FS) {
 274   ::ApplyFeatureFlag(FeatureBits, FS, ProcFeatures);
 275   return FeatureBits;
 276 }
 277
 278 bool MCSubtargetInfo::checkFeatures(StringRef FS) const {
 279   SubtargetFeatures T(FS);
 280   FeatureBitset Set, All;
 281   for (std::string F : T.getFeatures()) {
 282     ::ApplyFeatureFlag(Set, F, ProcFeatures);
 283     if (F[0] == '-')
 284       F[0] = '+';
 285     ::ApplyFeatureFlag(All, F, ProcFeatures);
 286   }
 287   return (FeatureBits & All) == Set;
 288 }
 289
 290 const MCSchedModel &MCSubtargetInfo::getSchedModelForCPU(StringRef CPU) const {
 291   assert(std::is_sorted(ProcDesc.begin(), ProcDesc.end()) &&
 292          "Processor machine model table is not sorted");
 293
 294   // Find entry
 295   const SubtargetSubTypeKV *CPUEntry = Find(CPU, ProcDesc);
 296
 297   if (!CPUEntry) {
 298     if (CPU != "help") // Don't error if the user asked for help.
 299       errs() << "'" << CPU
 300              << "' is not a recognized processor for this target"
 301              << " (ignoring processor)\n";
 302     return MCSchedModel::GetDefaultSchedModel();
 303   }
 304   assert(CPUEntry->SchedModel && "Missing processor SchedModel value");
 305   return *CPUEntry->SchedModel;
 306 }
 307
 308 InstrItineraryData
 309 MCSubtargetInfo::getInstrItineraryForCPU(StringRef CPU) const {
 310   const MCSchedModel &SchedModel = getSchedModelForCPU(CPU);
 311   return InstrItineraryData(SchedModel, Stages, OperandCycles, ForwardingPaths);
 312 }
 313
 314 void MCSubtargetInfo::initInstrItins(InstrItineraryData &InstrItins) const {
 315   InstrItins = InstrItineraryData(getSchedModel(), Stages, OperandCycles,
 316                                   ForwardingPaths);
 317 }
 318
 319 Optional<unsigned> MCSubtargetInfo::getCacheSize(unsigned Level) const {
 320   return Optional<unsigned>();
 321 }
 322
 323 Optional<unsigned>
 324 MCSubtargetInfo::getCacheAssociativity(unsigned Level) const {
 325   return Optional<unsigned>();
 326 }
 327
 328 Optional<unsigned> MCSubtargetInfo::getCacheLineSize(unsigned Level) const {
 329   return Optional<unsigned>();
 330 }
 331
 332 unsigned MCSubtargetInfo::getPrefetchDistance() const {
 333   return 0;
 334 }
 335
 336 unsigned MCSubtargetInfo::getMaxPrefetchIterationsAhead() const {
 337   return UINT_MAX;
 338 }
 339
 340 unsigned MCSubtargetInfo::getMinPrefetchStride() const {
 341   return 1;
 342 }