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/Triple.h"
22 #include "llvm/Support/DataTypes.h"
23 #include <bitset>
24 #include <vector>
25 
26 namespace llvm {
27 template <typename T> class ArrayRef;
28   class raw_ostream;
29   class StringRef;
30 
31 // A container class for subtarget features.
32 // This is convenient because std::bitset does not have a constructor
33 // with an initializer list of set bits.
34 const unsigned MAX_SUBTARGET_FEATURES = 128;
35 class FeatureBitset : public std::bitset<MAX_SUBTARGET_FEATURES> {
36 public:
37   // Cannot inherit constructors because it's not supported by VC++..
FeatureBitset()38   FeatureBitset() : bitset() {}
39 
FeatureBitset(const bitset<MAX_SUBTARGET_FEATURES> & B)40   FeatureBitset(const bitset<MAX_SUBTARGET_FEATURES>& B) : bitset(B) {}
41 
FeatureBitset(std::initializer_list<unsigned> Init)42   FeatureBitset(std::initializer_list<unsigned> Init) : bitset() {
43     for (auto I : Init)
44       set(I);
45   }
46 };
47 
48 //===----------------------------------------------------------------------===//
49 ///
50 /// SubtargetFeatureKV - Used to provide key value pairs for feature and
51 /// CPU bit flags.
52 //
53 struct SubtargetFeatureKV {
54   const char *Key;                      // K-V key string
55   const char *Desc;                     // Help descriptor
56   FeatureBitset Value;                  // K-V integer value
57   FeatureBitset Implies;                // K-V bit mask
58 
59   // Compare routine for std::lower_bound
60   bool operator<(StringRef S) const {
61     return StringRef(Key) < S;
62   }
63 
64   // Compare routine for std::is_sorted.
65   bool operator<(const SubtargetFeatureKV &Other) const {
66     return StringRef(Key) < StringRef(Other.Key);
67   }
68 };
69 
70 //===----------------------------------------------------------------------===//
71 ///
72 /// SubtargetInfoKV - Used to provide key value pairs for CPU and arbitrary
73 /// pointers.
74 //
75 struct SubtargetInfoKV {
76   const char *Key;                      // K-V key string
77   const void *Value;                    // K-V pointer value
78 
79   // Compare routine for std::lower_bound
80   bool operator<(StringRef S) const {
81     return StringRef(Key) < S;
82   }
83 };
84 
85 //===----------------------------------------------------------------------===//
86 ///
87 /// SubtargetFeatures - Manages the enabling and disabling of subtarget
88 /// specific features.  Features are encoded as a string of the form
89 ///   "+attr1,+attr2,-attr3,...,+attrN"
90 /// A comma separates each feature from the next (all lowercase.)
91 /// Each of the remaining features is prefixed with + or - indicating whether
92 /// that feature should be enabled or disabled contrary to the cpu
93 /// specification.
94 ///
95 
96 class SubtargetFeatures {
97   std::vector<std::string> Features;    // Subtarget features as a vector
98 public:
99   explicit SubtargetFeatures(StringRef Initial = "");
100 
101   /// Features string accessors.
102   std::string getString() const;
103 
104   /// Adding Features.
105   void AddFeature(StringRef String, bool Enable = true);
106 
107   /// ToggleFeature - Toggle a feature and update the feature bits.
108   static void ToggleFeature(FeatureBitset &Bits, StringRef String,
109                             ArrayRef<SubtargetFeatureKV> FeatureTable);
110 
111   /// Apply the feature flag and update the feature bits.
112   static void ApplyFeatureFlag(FeatureBitset &Bits, StringRef Feature,
113                                ArrayRef<SubtargetFeatureKV> FeatureTable);
114 
115   /// Get feature bits of a CPU.
116   FeatureBitset getFeatureBits(StringRef CPU,
117                           ArrayRef<SubtargetFeatureKV> CPUTable,
118                           ArrayRef<SubtargetFeatureKV> FeatureTable);
119 
120   /// Print feature string.
121   void print(raw_ostream &OS) const;
122 
123   // Dump 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
133