1 /*
2  * Copyright (C) 2011 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef ART_RUNTIME_ARCH_INSTRUCTION_SET_FEATURES_H_
18 #define ART_RUNTIME_ARCH_INSTRUCTION_SET_FEATURES_H_
19 
20 #include <iosfwd>
21 #include <memory>
22 #include <vector>
23 
24 #include "arch/instruction_set.h"
25 #include "base/macros.h"
26 
27 namespace art {
28 
29 class ArmInstructionSetFeatures;
30 class Arm64InstructionSetFeatures;
31 class MipsInstructionSetFeatures;
32 class Mips64InstructionSetFeatures;
33 class X86InstructionSetFeatures;
34 class X86_64InstructionSetFeatures;
35 
36 // Abstraction used to describe features of a different instruction sets.
37 class InstructionSetFeatures {
38  public:
39   // Process a CPU variant string for the given ISA and create an InstructionSetFeatures.
40   static std::unique_ptr<const InstructionSetFeatures> FromVariant(InstructionSet isa,
41                                                                    const std::string& variant,
42                                                                    std::string* error_msg);
43 
44   // Parse a bitmap for the given isa and create an InstructionSetFeatures.
45   static std::unique_ptr<const InstructionSetFeatures> FromBitmap(InstructionSet isa,
46                                                                   uint32_t bitmap);
47 
48   // Turn C pre-processor #defines into the equivalent instruction set features for kRuntimeISA.
49   static std::unique_ptr<const InstructionSetFeatures> FromCppDefines();
50 
51   // Check if run-time detection of instruction set features is supported.
52   //
53   // Return: true - if run-time detection is supported on a target device.
54   //         false - otherwise
IsRuntimeDetectionSupported()55   static bool IsRuntimeDetectionSupported() {
56     return FromRuntimeDetection() != nullptr;
57   }
58 
59   // Use run-time detection to get instruction set features.
60   //
61   // Return: a set of detected features or nullptr if runtime detection is not
62   //         supported on a target.
63   static std::unique_ptr<const InstructionSetFeatures> FromRuntimeDetection();
64 
65   // Process /proc/cpuinfo and use kRuntimeISA to produce InstructionSetFeatures.
66   static std::unique_ptr<const InstructionSetFeatures> FromCpuInfo();
67 
68   // Process the auxiliary vector AT_HWCAP entry and use kRuntimeISA to produce
69   // InstructionSetFeatures.
70   static std::unique_ptr<const InstructionSetFeatures> FromHwcap();
71 
72   // Use assembly tests of the current runtime (ie kRuntimeISA) to determine the
73   // InstructionSetFeatures. This works around kernel bugs in AT_HWCAP and /proc/cpuinfo.
74   static std::unique_ptr<const InstructionSetFeatures> FromAssembly();
75 
76   // Parse a string of the form "div,-atomic_ldrd_strd" adding and removing these features to
77   // create a new InstructionSetFeatures.
78   std::unique_ptr<const InstructionSetFeatures> AddFeaturesFromString(
79       const std::string& feature_list, std::string* error_msg) const WARN_UNUSED;
80 
81   // Are these features the same as the other given features?
82   virtual bool Equals(const InstructionSetFeatures* other) const = 0;
83 
84   // For testing purposes we want to make sure that the system we run on has at
85   // least the options we claim it has. In this cases Equals() does not
86   // suffice and will cause the test to fail, since the runtime cpu feature
87   // detection claims more capabilities then statically specified from the
88   // build system.
89   //
90   // A good example of this is the armv8 ART test target that declares
91   // "CPU_VARIANT=generic". If the generic target is specified and the code
92   // is run on a platform with enhanced capabilities, the
93   // instruction_set_features test will fail if we resort to using Equals()
94   // between statically defined cpu features and runtime cpu features.
95   //
96   // For now we default this to Equals() in case the architecture does not
97   // provide it.
HasAtLeast(const InstructionSetFeatures * other)98   virtual bool HasAtLeast(const InstructionSetFeatures* other) const {
99     return Equals(other);
100   }
101 
102   // Return the ISA these features relate to.
103   virtual InstructionSet GetInstructionSet() const = 0;
104 
105   // Return a bitmap that represents the features. ISA specific.
106   virtual uint32_t AsBitmap() const = 0;
107 
108   // Return a string of the form "div,lpae" or "none".
109   virtual std::string GetFeatureString() const = 0;
110 
111   // Down cast this ArmInstructionFeatures.
112   const ArmInstructionSetFeatures* AsArmInstructionSetFeatures() const;
113 
114   // Down cast this Arm64InstructionFeatures.
115   const Arm64InstructionSetFeatures* AsArm64InstructionSetFeatures() const;
116 
117   // Down cast this MipsInstructionFeatures.
118   const MipsInstructionSetFeatures* AsMipsInstructionSetFeatures() const;
119 
120   // Down cast this Mips64InstructionFeatures.
121   const Mips64InstructionSetFeatures* AsMips64InstructionSetFeatures() const;
122 
123   // Down cast this X86InstructionFeatures.
124   const X86InstructionSetFeatures* AsX86InstructionSetFeatures() const;
125 
126   // Down cast this X86_64InstructionFeatures.
127   const X86_64InstructionSetFeatures* AsX86_64InstructionSetFeatures() const;
128 
~InstructionSetFeatures()129   virtual ~InstructionSetFeatures() {}
130 
131  protected:
InstructionSetFeatures()132   InstructionSetFeatures() {}
133 
134   // Returns true if variant appears in the array variants.
135   static bool FindVariantInArray(const char* const variants[], size_t num_variants,
136                                  const std::string& variant);
137 
138   // Add architecture specific features in sub-classes.
139   virtual std::unique_ptr<const InstructionSetFeatures>
140       AddFeaturesFromSplitString(const std::vector<std::string>& features,
141                                  std::string* error_msg) const = 0;
142 
143   // Add run-time detected architecture specific features in sub-classes.
144   virtual std::unique_ptr<const InstructionSetFeatures>
145       AddRuntimeDetectedFeatures(const InstructionSetFeatures *features ATTRIBUTE_UNUSED) const;
146 
147  private:
148   DISALLOW_COPY_AND_ASSIGN(InstructionSetFeatures);
149 };
150 std::ostream& operator<<(std::ostream& os, const InstructionSetFeatures& rhs);
151 
152 }  // namespace art
153 
154 #endif  // ART_RUNTIME_ARCH_INSTRUCTION_SET_FEATURES_H_
155