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
26namespace art {
27
28static constexpr bool kImTableHashUseName = true;
29static constexpr bool kImTableHashUseCoefficients = true;
30
31// Magic configuration that minimizes some common runtime calls.
32static constexpr uint32_t kImTableHashCoefficientClass = 427;
33static constexpr uint32_t kImTableHashCoefficientName = 16;
34static constexpr uint32_t kImTableHashCoefficientSignature = 14;
35
36inline 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
85inline 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