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