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26 
27 #ifndef VIXL_AARCH64_CPU_FEATURES_AUDITOR_AARCH64_H_
28 #define VIXL_AARCH64_CPU_FEATURES_AUDITOR_AARCH64_H_
29 
30 #include <iostream>
31 
32 #include "cpu-features.h"
33 #include "decoder-aarch64.h"
34 
35 namespace vixl {
36 namespace aarch64 {
37 
38 // This visitor records the CPU features that each decoded instruction requires.
39 // It provides:
40 //  - the set of CPU features required by the most recently decoded instruction,
41 //  - a cumulative set of encountered CPU features,
42 //  - an optional list of 'available' CPU features.
43 //
44 // Primarily, this allows the Disassembler and Simulator to share the same CPU
45 // features logic. However, it can be used standalone to scan code blocks for
46 // CPU features.
47 class CPUFeaturesAuditor : public DecoderVisitor {
48  public:
49   // Construction arguments:
50   //   - If a decoder is specified, the CPUFeaturesAuditor automatically
51   //     registers itself as a visitor. Otherwise, this can be done manually.
52   //
53   //   - If an `available` features list is provided, it is used as a hint in
54   //     cases where instructions may be provided by multiple separate features.
55   //     An example of this is FP&SIMD loads and stores: some of these are used
56   //     in both FP and integer SIMD code. If exactly one of those features is
57   //     in `available` when one of these instructions is encountered, then the
58   //     auditor will record that feature. Otherwise, it will record _both_
59   //     features.
60   explicit CPUFeaturesAuditor(
61       Decoder* decoder, const CPUFeatures& available = CPUFeatures::None())
available_(available)62       : available_(available), decoder_(decoder) {
63     if (decoder_ != NULL) decoder_->AppendVisitor(this);
64   }
65 
66   explicit CPUFeaturesAuditor(
67       const CPUFeatures& available = CPUFeatures::None())
available_(available)68       : available_(available), decoder_(NULL) {}
69 
~CPUFeaturesAuditor()70   virtual ~CPUFeaturesAuditor() {
71     if (decoder_ != NULL) decoder_->RemoveVisitor(this);
72   }
73 
ResetSeenFeatures()74   void ResetSeenFeatures() {
75     seen_ = CPUFeatures::None();
76     last_instruction_ = CPUFeatures::None();
77   }
78 
79   // Query or set available CPUFeatures.
GetAvailableFeatures()80   const CPUFeatures& GetAvailableFeatures() const { return available_; }
SetAvailableFeatures(const CPUFeatures & available)81   void SetAvailableFeatures(const CPUFeatures& available) {
82     available_ = available;
83   }
84 
85   // Query CPUFeatures seen since construction (or the last call to `Reset()`).
GetSeenFeatures()86   const CPUFeatures& GetSeenFeatures() const { return seen_; }
87 
88   // Query CPUFeatures from the last instruction visited by this auditor.
GetInstructionFeatures()89   const CPUFeatures& GetInstructionFeatures() const {
90     return last_instruction_;
91   }
92 
InstructionIsAvailable()93   bool InstructionIsAvailable() const {
94     return available_.Has(last_instruction_);
95   }
96 
97   // The common CPUFeatures interface operates on the available_ list.
GetCPUFeatures()98   CPUFeatures* GetCPUFeatures() { return &available_; }
SetCPUFeatures(const CPUFeatures & available)99   void SetCPUFeatures(const CPUFeatures& available) {
100     SetAvailableFeatures(available);
101   }
102 
103 // Declare all Visitor functions.
104 #define DECLARE(A) \
105   virtual void Visit##A(const Instruction* instr) VIXL_OVERRIDE;
106   VISITOR_LIST(DECLARE)
107 #undef DECLARE
108 
109  private:
110   class RecordInstructionFeaturesScope;
111 
112   void LoadStoreHelper(const Instruction* instr);
113   void LoadStorePairHelper(const Instruction* instr);
114 
115   CPUFeatures seen_;
116   CPUFeatures last_instruction_;
117   CPUFeatures available_;
118 
119   Decoder* decoder_;
120 };
121 
122 }  // namespace aarch64
123 }  // namespace vixl
124 
125 #endif  // VIXL_AARCH64_CPU_FEATURES_AUDITOR_AARCH64_H_
126