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      1 /*
      2  * Copyright (C) 2014 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_ARM_INSTRUCTION_SET_FEATURES_ARM_H_
     18 #define ART_RUNTIME_ARCH_ARM_INSTRUCTION_SET_FEATURES_ARM_H_
     19 
     20 #include "arch/instruction_set_features.h"
     21 
     22 namespace art {
     23 
     24 class ArmInstructionSetFeatures;
     25 using ArmFeaturesUniquePtr = std::unique_ptr<const ArmInstructionSetFeatures>;
     26 
     27 // Instruction set features relevant to the ARM architecture.
     28 class ArmInstructionSetFeatures FINAL : public InstructionSetFeatures {
     29  public:
     30   // Process a CPU variant string like "krait" or "cortex-a15" and create InstructionSetFeatures.
     31   static ArmFeaturesUniquePtr FromVariant(const std::string& variant, std::string* error_msg);
     32 
     33   // Parse a bitmap and create an InstructionSetFeatures.
     34   static ArmFeaturesUniquePtr FromBitmap(uint32_t bitmap);
     35 
     36   // Turn C pre-processor #defines into the equivalent instruction set features.
     37   static ArmFeaturesUniquePtr FromCppDefines();
     38 
     39   // Process /proc/cpuinfo and use kRuntimeISA to produce InstructionSetFeatures.
     40   static ArmFeaturesUniquePtr FromCpuInfo();
     41 
     42   // Process the auxiliary vector AT_HWCAP entry and use kRuntimeISA to produce
     43   // InstructionSetFeatures.
     44   static ArmFeaturesUniquePtr FromHwcap();
     45 
     46   // Use assembly tests of the current runtime (ie kRuntimeISA) to determine the
     47   // InstructionSetFeatures. This works around kernel bugs in AT_HWCAP and /proc/cpuinfo.
     48   static ArmFeaturesUniquePtr FromAssembly();
     49 
     50   bool Equals(const InstructionSetFeatures* other) const OVERRIDE;
     51 
     52   bool HasAtLeast(const InstructionSetFeatures* other) const OVERRIDE;
     53 
     54   InstructionSet GetInstructionSet() const OVERRIDE {
     55     return kArm;
     56   }
     57 
     58   uint32_t AsBitmap() const OVERRIDE;
     59 
     60   // Return a string of the form "div,lpae" or "none".
     61   std::string GetFeatureString() const OVERRIDE;
     62 
     63   // Is the divide instruction feature enabled?
     64   bool HasDivideInstruction() const {
     65       return has_div_;
     66   }
     67 
     68   // Are the ldrd and strd instructions atomic? This is commonly true when the Large Physical
     69   // Address Extension (LPAE) is present.
     70   bool HasAtomicLdrdAndStrd() const {
     71     return has_atomic_ldrd_strd_;
     72   }
     73 
     74   // Are ARMv8-A instructions available?
     75   bool HasARMv8AInstructions() const {
     76     return has_armv8a_;
     77   }
     78 
     79   virtual ~ArmInstructionSetFeatures() {}
     80 
     81  protected:
     82   // Parse a vector of the form "div", "lpae" adding these to a new ArmInstructionSetFeatures.
     83   std::unique_ptr<const InstructionSetFeatures>
     84       AddFeaturesFromSplitString(const std::vector<std::string>& features,
     85                                  std::string* error_msg) const OVERRIDE;
     86 
     87  private:
     88   ArmInstructionSetFeatures(bool has_div,
     89                             bool has_atomic_ldrd_strd,
     90                             bool has_armv8a)
     91       : InstructionSetFeatures(),
     92         has_div_(has_div),
     93         has_atomic_ldrd_strd_(has_atomic_ldrd_strd),
     94         has_armv8a_(has_armv8a) {}
     95 
     96   // Bitmap positions for encoding features as a bitmap.
     97   enum {
     98     kDivBitfield = 1 << 0,
     99     kAtomicLdrdStrdBitfield = 1 << 1,
    100     kARMv8A = 1 << 2,
    101   };
    102 
    103   const bool has_div_;
    104   const bool has_atomic_ldrd_strd_;
    105   const bool has_armv8a_;
    106 
    107   DISALLOW_COPY_AND_ASSIGN(ArmInstructionSetFeatures);
    108 };
    109 
    110 }  // namespace art
    111 
    112 #endif  // ART_RUNTIME_ARCH_ARM_INSTRUCTION_SET_FEATURES_ARM_H_
    113