include/llvm/MC/SubtargetFeature.h

   1 //===- llvm/MC/SubtargetFeature.h - CPU characteristics ---------*- C++ -*-===//
   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 /// \file Defines and manages user or tool specified CPU characteristics.
  10 /// The intent is to be able to package specific features that should or should
  11 /// not be used on a specific target processor.  A tool, such as llc, could, as
  12 /// as example, gather chip info from the command line, a long with features
  13 /// that should be used on that chip.
  14 //
  15 //===----------------------------------------------------------------------===//
  16
  17 #ifndef LLVM_MC_SUBTARGETFEATURE_H
  18 #define LLVM_MC_SUBTARGETFEATURE_H
  19
  20 #include "llvm/ADT/StringRef.h"
  21 #include <bitset>
  22 #include <initializer_list>
  23 #include <string>
  24 #include <vector>
  25
  26 namespace llvm {
  27
  28 template <typename T> class ArrayRef;
  29 class raw_ostream;
  30 class Triple;
  31
  32 const unsigned MAX_SUBTARGET_FEATURES = 192;
  33 /// Container class for subtarget features.
  34 /// This is convenient because std::bitset does not have a constructor
  35 /// with an initializer list of set bits.
  36 class FeatureBitset : public std::bitset<MAX_SUBTARGET_FEATURES> {
  37 public:
  38   // Cannot inherit constructors because it's not supported by VC++..
  39   FeatureBitset() = default;
  40
  41   FeatureBitset(const bitset<MAX_SUBTARGET_FEATURES>& B) : bitset(B) {}
  42
  43   FeatureBitset(std::initializer_list<unsigned> Init) {
  44     for (auto I : Init)
  45       set(I);
  46   }
  47 };
  48
  49 //===----------------------------------------------------------------------===//
  50
  51 /// Used to provide key value pairs for feature and CPU bit flags.
  52 struct SubtargetFeatureKV {
  53   const char *Key;                      ///< K-V key string
  54   const char *Desc;                     ///< Help descriptor
  55   unsigned Value;                       ///< K-V integer value
  56   FeatureBitset Implies;                ///< K-V bit mask
  57
  58   /// Compare routine for std::lower_bound
  59   bool operator<(StringRef S) const {
  60     return StringRef(Key) < S;
  61   }
  62
  63   /// Compare routine for std::is_sorted.
  64   bool operator<(const SubtargetFeatureKV &Other) const {
  65     return StringRef(Key) < StringRef(Other.Key);
  66   }
  67 };
  68
  69 //===----------------------------------------------------------------------===//
  70
  71 /// Used to provide key value pairs for CPU and arbitrary pointers.
  72 struct SubtargetInfoKV {
  73   const char *Key;                      ///< K-V key string
  74   const void *Value;                    ///< K-V pointer value
  75
  76   /// Compare routine for std::lower_bound
  77   bool operator<(StringRef S) const {
  78     return StringRef(Key) < S;
  79   }
  80 };
  81
  82 //===----------------------------------------------------------------------===//
  83
  84 /// Manages the enabling and disabling of subtarget specific features.
  85 ///
  86 /// Features are encoded as a string of the form
  87 ///   "+attr1,+attr2,-attr3,...,+attrN"
  88 /// A comma separates each feature from the next (all lowercase.)
  89 /// Each of the remaining features is prefixed with + or - indicating whether
  90 /// that feature should be enabled or disabled contrary to the cpu
  91 /// specification.
  92 class SubtargetFeatures {
  93   std::vector<std::string> Features;    ///< Subtarget features as a vector
  94
  95 public:
  96   explicit SubtargetFeatures(StringRef Initial = "");
  97
  98   /// Returns features as a string.
  99   std::string getString() const;
 100
 101   /// Adds Features.
 102   void AddFeature(StringRef String, bool Enable = true);
 103
 104   /// Toggles a feature and update the feature bits.
 105   static void ToggleFeature(FeatureBitset &Bits, StringRef String,
 106                             ArrayRef<SubtargetFeatureKV> FeatureTable);
 107
 108   /// Applies the feature flag and update the feature bits.
 109   static void ApplyFeatureFlag(FeatureBitset &Bits, StringRef Feature,
 110                                ArrayRef<SubtargetFeatureKV> FeatureTable);
 111
 112   /// Returns feature bits of a CPU.
 113   FeatureBitset getFeatureBits(StringRef CPU,
 114                                ArrayRef<SubtargetFeatureKV> CPUTable,
 115                                ArrayRef<SubtargetFeatureKV> FeatureTable);
 116
 117   /// Returns the vector of individual subtarget features.
 118   const std::vector<std::string> &getFeatures() const { return Features; }
 119
 120   /// Prints feature string.
 121   void print(raw_ostream &OS) const;
 122
 123   // Dumps feature info.
 124   void dump() const;
 125
 126   /// Adds the default features for the specified target triple.
 127   void getDefaultSubtargetFeatures(const Triple& Triple);
 128 };
 129
 130 } // end namespace llvm
 131
 132 #endif // LLVM_MC_SUBTARGETFEATURE_H