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 <vector>
22 #include "llvm/ADT/Triple.h"
23 #include "llvm/Support/DataTypes.h"
24 
25 namespace llvm {
26   class raw_ostream;
27   class StringRef;
28 
29 //===----------------------------------------------------------------------===//
30 ///
31 /// SubtargetFeatureKV - Used to provide key value pairs for feature and
32 /// CPU bit flags.
33 //
34 struct SubtargetFeatureKV {
35   const char *Key;                      // K-V key string
36   const char *Desc;                     // Help descriptor
37   uint64_t Value;                       // K-V integer value
38   uint64_t Implies;                     // K-V bit mask
39 
40   // Compare routine for std binary search
41   bool operator<(const SubtargetFeatureKV &S) const {
42     return strcmp(Key, S.Key) < 0;
43   }
44 };
45 
46 //===----------------------------------------------------------------------===//
47 ///
48 /// SubtargetInfoKV - Used to provide key value pairs for CPU and arbitrary
49 /// pointers.
50 //
51 struct SubtargetInfoKV {
52   const char *Key;                      // K-V key string
53   void *Value;                          // K-V pointer value
54 
55   // Compare routine for std binary search
56   bool operator<(const SubtargetInfoKV &S) const {
57     return strcmp(Key, S.Key) < 0;
58   }
59 };
60 
61 //===----------------------------------------------------------------------===//
62 ///
63 /// SubtargetFeatures - Manages the enabling and disabling of subtarget
64 /// specific features.  Features are encoded as a string of the form
65 ///   "cpu,+attr1,+attr2,-attr3,...,+attrN"
66 /// A comma separates each feature from the next (all lowercase.)
67 /// The first feature is always the CPU subtype (eg. pentiumm).  If the CPU
68 /// value is "generic" then the CPU subtype should be generic for the target.
69 /// Each of the remaining features is prefixed with + or - indicating whether
70 /// that feature should be enabled or disabled contrary to the cpu
71 /// specification.
72 ///
73 
74 class SubtargetFeatures {
75   std::vector<std::string> Features;    // Subtarget features as a vector
76 public:
77   explicit SubtargetFeatures(const StringRef Initial = "");
78 
79   /// Features string accessors.
80   std::string getString() const;
81 
82   /// Adding Features.
83   void AddFeature(const StringRef String, bool IsEnabled = true);
84 
85   /// ToggleFeature - Toggle a feature and returns the newly updated feature
86   /// bits.
87   uint64_t ToggleFeature(uint64_t Bits, const StringRef String,
88                          const SubtargetFeatureKV *FeatureTable,
89                          size_t FeatureTableSize);
90 
91   /// Get feature bits of a CPU.
92   uint64_t getFeatureBits(const StringRef CPU,
93                           const SubtargetFeatureKV *CPUTable,
94                           size_t CPUTableSize,
95                           const SubtargetFeatureKV *FeatureTable,
96                           size_t FeatureTableSize);
97 
98   /// Get scheduling itinerary of a CPU.
99   void *getItinerary(const StringRef CPU,
100                      const SubtargetInfoKV *Table, size_t TableSize);
101 
102   /// Print feature string.
103   void print(raw_ostream &OS) const;
104 
105   // Dump feature info.
106   void dump() const;
107 
108   /// Retrieve a formatted string of the default features for the specified
109   /// target triple.
110   void getDefaultSubtargetFeatures(const Triple& Triple);
111 };
112 
113 } // End namespace llvm
114 
115 #endif
116