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      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_OPTIMIZING_REGISTER_ALLOCATOR_H_
     18 #define ART_COMPILER_OPTIMIZING_REGISTER_ALLOCATOR_H_
     19 
     20 #include "arch/instruction_set.h"
     21 #include "base/array_ref.h"
     22 #include "base/arena_object.h"
     23 #include "base/macros.h"
     24 
     25 namespace art {
     26 
     27 class CodeGenerator;
     28 class HBasicBlock;
     29 class HGraph;
     30 class HInstruction;
     31 class HParallelMove;
     32 class LiveInterval;
     33 class Location;
     34 class SsaLivenessAnalysis;
     35 
     36 /**
     37  * Base class for any register allocator.
     38  */
     39 class RegisterAllocator : public DeletableArenaObject<kArenaAllocRegisterAllocator> {
     40  public:
     41   enum Strategy {
     42     kRegisterAllocatorLinearScan,
     43     kRegisterAllocatorGraphColor
     44   };
     45 
     46   static constexpr Strategy kRegisterAllocatorDefault = kRegisterAllocatorLinearScan;
     47 
     48   static std::unique_ptr<RegisterAllocator> Create(ScopedArenaAllocator* allocator,
     49                                                    CodeGenerator* codegen,
     50                                                    const SsaLivenessAnalysis& analysis,
     51                                                    Strategy strategy = kRegisterAllocatorDefault);
     52 
     53   virtual ~RegisterAllocator();
     54 
     55   // Main entry point for the register allocator. Given the liveness analysis,
     56   // allocates registers to live intervals.
     57   virtual void AllocateRegisters() = 0;
     58 
     59   // Validate that the register allocator did not allocate the same register to
     60   // intervals that intersect each other. Returns false if it failed.
     61   virtual bool Validate(bool log_fatal_on_failure) = 0;
     62 
     63   static bool CanAllocateRegistersFor(const HGraph& graph,
     64                                       InstructionSet instruction_set);
     65 
     66   // Verifies that live intervals do not conflict. Used by unit testing.
     67   static bool ValidateIntervals(ArrayRef<LiveInterval* const> intervals,
     68                                 size_t number_of_spill_slots,
     69                                 size_t number_of_out_slots,
     70                                 const CodeGenerator& codegen,
     71                                 bool processing_core_registers,
     72                                 bool log_fatal_on_failure);
     73 
     74   static constexpr const char* kRegisterAllocatorPassName = "register";
     75 
     76  protected:
     77   RegisterAllocator(ScopedArenaAllocator* allocator,
     78                     CodeGenerator* codegen,
     79                     const SsaLivenessAnalysis& analysis);
     80 
     81   // Split `interval` at the position `position`. The new interval starts at `position`.
     82   // If `position` is at the start of `interval`, returns `interval` with its
     83   // register location(s) cleared.
     84   static LiveInterval* Split(LiveInterval* interval, size_t position);
     85 
     86   // Split `interval` at a position between `from` and `to`. The method will try
     87   // to find an optimal split position.
     88   LiveInterval* SplitBetween(LiveInterval* interval, size_t from, size_t to);
     89 
     90   ScopedArenaAllocator* const allocator_;
     91   CodeGenerator* const codegen_;
     92   const SsaLivenessAnalysis& liveness_;
     93 };
     94 
     95 }  // namespace art
     96 
     97 #endif  // ART_COMPILER_OPTIMIZING_REGISTER_ALLOCATOR_H_
     98