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      1 /*
      2  * Copyright (C) 2017 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_CODE_OFFSET_H_
     18 #define ART_RUNTIME_ARCH_CODE_OFFSET_H_
     19 
     20 #include <iosfwd>
     21 
     22 #include <android-base/logging.h>
     23 
     24 #include "base/bit_utils.h"
     25 #include "base/macros.h"
     26 #include "instruction_set.h"
     27 
     28 namespace art {
     29 
     30 // CodeOffset is a holder for compressed code offsets. Since some architectures have alignment
     31 // requirements it is possible to compress code offsets to reduce stack map sizes.
     32 class CodeOffset {
     33  public:
     34   ALWAYS_INLINE static CodeOffset FromOffset(uint32_t offset, InstructionSet isa = kRuntimeISA) {
     35     return CodeOffset(offset / GetInstructionSetInstructionAlignment(isa));
     36   }
     37 
     38   ALWAYS_INLINE static CodeOffset FromCompressedOffset(uint32_t offset) {
     39     return CodeOffset(offset);
     40   }
     41 
     42   ALWAYS_INLINE uint32_t Uint32Value(InstructionSet isa = kRuntimeISA) const {
     43     uint32_t decoded = value_ * GetInstructionSetInstructionAlignment(isa);
     44     DCHECK_GE(decoded, value_) << "Integer overflow";
     45     return decoded;
     46   }
     47 
     48   // Return compressed internal value.
     49   ALWAYS_INLINE uint32_t CompressedValue() const {
     50     return value_;
     51   }
     52 
     53   ALWAYS_INLINE CodeOffset() = default;
     54   ALWAYS_INLINE CodeOffset(const CodeOffset&) = default;
     55   ALWAYS_INLINE CodeOffset& operator=(const CodeOffset&) = default;
     56   ALWAYS_INLINE CodeOffset& operator=(CodeOffset&&) = default;
     57 
     58  private:
     59   ALWAYS_INLINE explicit CodeOffset(uint32_t value) : value_(value) {}
     60 
     61   uint32_t value_ = 0u;
     62 };
     63 
     64 inline bool operator==(const CodeOffset& a, const CodeOffset& b) {
     65   return a.CompressedValue() == b.CompressedValue();
     66 }
     67 
     68 inline bool operator!=(const CodeOffset& a, const CodeOffset& b) {
     69   return !(a == b);
     70 }
     71 
     72 inline bool operator<(const CodeOffset& a, const CodeOffset& b) {
     73   return a.CompressedValue() < b.CompressedValue();
     74 }
     75 
     76 inline bool operator<=(const CodeOffset& a, const CodeOffset& b) {
     77   return a.CompressedValue() <= b.CompressedValue();
     78 }
     79 
     80 inline bool operator>(const CodeOffset& a, const CodeOffset& b) {
     81   return a.CompressedValue() > b.CompressedValue();
     82 }
     83 
     84 inline bool operator>=(const CodeOffset& a, const CodeOffset& b) {
     85   return a.CompressedValue() >= b.CompressedValue();
     86 }
     87 
     88 inline std::ostream& operator<<(std::ostream& os, const CodeOffset& offset) {
     89   return os << offset.Uint32Value();
     90 }
     91 
     92 }  // namespace art
     93 
     94 #endif  // ART_RUNTIME_ARCH_CODE_OFFSET_H_
     95