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_COMPILER_UTILS_STRING_REFERENCE_H_ 18 #define ART_COMPILER_UTILS_STRING_REFERENCE_H_ 19 20 #include <stdint.h> 21 22 #include "base/logging.h" 23 #include "utf-inl.h" 24 25 namespace art { 26 27 class DexFile; 28 29 // A string is uniquely located by its DexFile and the string_ids_ table index into that DexFile. 30 struct StringReference { StringReferenceStringReference31 StringReference(const DexFile* file, uint32_t index) : dex_file(file), string_index(index) { } 32 33 const DexFile* dex_file; 34 uint32_t string_index; 35 }; 36 37 // Compare the actual referenced string values. Used for string reference deduplication. 38 struct StringReferenceValueComparator { operatorStringReferenceValueComparator39 bool operator()(StringReference sr1, StringReference sr2) const { 40 // Note that we want to deduplicate identical strings even if they are referenced 41 // by different dex files, so we need some (any) total ordering of strings, rather 42 // than references. However, the references should usually be from the same dex file, 43 // so we choose the dex file string ordering so that we can simply compare indexes 44 // and avoid the costly string comparison in the most common case. 45 if (sr1.dex_file == sr2.dex_file) { 46 // Use the string order enforced by the dex file verifier. 47 DCHECK_EQ( 48 sr1.string_index < sr2.string_index, 49 CompareModifiedUtf8ToModifiedUtf8AsUtf16CodePointValues( 50 sr1.dex_file->GetStringData(sr1.dex_file->GetStringId(sr1.string_index)), 51 sr1.dex_file->GetStringData(sr2.dex_file->GetStringId(sr2.string_index))) < 0); 52 return sr1.string_index < sr2.string_index; 53 } else { 54 // Cannot compare indexes, so do the string comparison. 55 return CompareModifiedUtf8ToModifiedUtf8AsUtf16CodePointValues( 56 sr1.dex_file->GetStringData(sr1.dex_file->GetStringId(sr1.string_index)), 57 sr1.dex_file->GetStringData(sr2.dex_file->GetStringId(sr2.string_index))) < 0; 58 } 59 } 60 }; 61 62 } // namespace art 63 64 #endif // ART_COMPILER_UTILS_STRING_REFERENCE_H_ 65