1 /* 2 * Copyright (C) 2016 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_IMTABLE_INL_H_ 18 #define ART_RUNTIME_IMTABLE_INL_H_ 19 20 #include "imtable.h" 21 22 #include "art_method-inl.h" 23 #include "dex_file.h" 24 #include "utf.h" 25 26 namespace art { 27 28 static constexpr bool kImTableHashUseName = true; 29 static constexpr bool kImTableHashUseCoefficients = true; 30 31 // Magic configuration that minimizes some common runtime calls. 32 static constexpr uint32_t kImTableHashCoefficientClass = 427; 33 static constexpr uint32_t kImTableHashCoefficientName = 16; 34 static constexpr uint32_t kImTableHashCoefficientSignature = 14; 35 36 inline void ImTable::GetImtHashComponents(ArtMethod* method, 37 uint32_t* class_hash, 38 uint32_t* name_hash, 39 uint32_t* signature_hash) { 40 if (kImTableHashUseName) { 41 if (method->IsProxyMethod()) { 42 *class_hash = 0; 43 *name_hash = 0; 44 *signature_hash = 0; 45 return; 46 } 47 48 const DexFile* dex_file = method->GetDexFile(); 49 const DexFile::MethodId& method_id = dex_file->GetMethodId(method->GetDexMethodIndex()); 50 51 // Class descriptor for the class component. 52 *class_hash = ComputeModifiedUtf8Hash(dex_file->GetMethodDeclaringClassDescriptor(method_id)); 53 54 // Method name for the method component. 55 *name_hash = ComputeModifiedUtf8Hash(dex_file->GetMethodName(method_id)); 56 57 const DexFile::ProtoId& proto_id = dex_file->GetMethodPrototype(method_id); 58 59 // Read the proto for the signature component. 60 uint32_t tmp = ComputeModifiedUtf8Hash( 61 dex_file->GetTypeDescriptor(dex_file->GetTypeId(proto_id.return_type_idx_))); 62 63 // Mix in the argument types. 64 // Note: we could consider just using the shorty. This would be faster, at the price of 65 // potential collisions. 66 const DexFile::TypeList* param_types = dex_file->GetProtoParameters(proto_id); 67 if (param_types != nullptr) { 68 for (size_t i = 0; i != param_types->Size(); ++i) { 69 const DexFile::TypeItem& type = param_types->GetTypeItem(i); 70 tmp = 31 * tmp + ComputeModifiedUtf8Hash( 71 dex_file->GetTypeDescriptor(dex_file->GetTypeId(type.type_idx_))); 72 } 73 } 74 75 *signature_hash = tmp; 76 return; 77 } else { 78 *class_hash = method->GetDexMethodIndex(); 79 *name_hash = 0; 80 *signature_hash = 0; 81 return; 82 } 83 } 84 85 inline uint32_t ImTable::GetImtIndex(ArtMethod* method) { 86 uint32_t class_hash, name_hash, signature_hash; 87 GetImtHashComponents(method, &class_hash, &name_hash, &signature_hash); 88 89 uint32_t mixed_hash; 90 if (!kImTableHashUseCoefficients) { 91 mixed_hash = class_hash + name_hash + signature_hash; 92 } else { 93 mixed_hash = kImTableHashCoefficientClass * class_hash + 94 kImTableHashCoefficientName * name_hash + 95 kImTableHashCoefficientSignature * signature_hash; 96 } 97 98 return mixed_hash % ImTable::kSize; 99 } 100 101 } // namespace art 102 103 #endif // ART_RUNTIME_IMTABLE_INL_H_ 104 105