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