SubtargetFeature.h revision 639aa87bee77fe2d83f0978ae1eea53e49def324 
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
25namespace 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//
34struct 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//
51struct 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
74class SubtargetFeatures {
75  std::vector<std::string> Features;    // Subtarget features as a vector
76public:
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