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 
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::lower_bound
41   bool operator<(StringRef S) const {
42     return StringRef(Key) < S;
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   const void *Value;                    // K-V pointer value
54 
55   // Compare routine for std::lower_bound
56   bool operator<(StringRef S) const {
57     return StringRef(Key) < S;
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 ///   "+attr1,+attr2,-attr3,...,+attrN"
66 /// A comma separates each feature from the next (all lowercase.)
67 /// Each of the remaining features is prefixed with + or - indicating whether
68 /// that feature should be enabled or disabled contrary to the cpu
69 /// specification.
70 ///
71 
72 class SubtargetFeatures {
73   std::vector<std::string> Features;    // Subtarget features as a vector
74 public:
75   explicit SubtargetFeatures(StringRef Initial = "");
76 
77   /// Features string accessors.
78   std::string getString() const;
79 
80   /// Adding Features.
81   void AddFeature(StringRef String, bool Enable = true);
82 
83   /// ToggleFeature - Toggle a feature and returns the newly updated feature
84   /// bits.
85   uint64_t ToggleFeature(uint64_t Bits, StringRef String,
86                          ArrayRef<SubtargetFeatureKV> FeatureTable);
87 
88   /// Get feature bits of a CPU.
89   uint64_t getFeatureBits(StringRef CPU,
90                           ArrayRef<SubtargetFeatureKV> CPUTable,
91                           ArrayRef<SubtargetFeatureKV> FeatureTable);
92 
93   /// Print feature string.
94   void print(raw_ostream &OS) const;
95 
96   // Dump feature info.
97   void dump() const;
98 
99   /// Adds the default features for the specified target triple.
100   void getDefaultSubtargetFeatures(const Triple& Triple);
101 };
102 
103 } // End namespace llvm
104 
105 #endif
106