1 /*
2  * Copyright (C) 2007 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 package com.android.dx.ssa.back;
18 
19 import com.android.dx.ssa.BasicRegisterMapper;
20 import com.android.dx.ssa.RegisterMapper;
21 import com.android.dx.ssa.SsaMethod;
22 
23 /**
24  * A register allocator that maps SSA register n to Rop register 2*n,
25  * essentially preserving the original mapping and remaining agnostic
26  * about normal or wide categories. Used for debugging.
27  */
28 public class NullRegisterAllocator extends RegisterAllocator {
29     /** {@inheritDoc} */
NullRegisterAllocator(SsaMethod ssaMeth, InterferenceGraph interference)30     public NullRegisterAllocator(SsaMethod ssaMeth,
31             InterferenceGraph interference) {
32         super(ssaMeth, interference);
33     }
34 
35     /** {@inheritDoc} */
36     @Override
wantsParamsMovedHigh()37     public boolean wantsParamsMovedHigh() {
38         // We're not smart enough for this.
39         return false;
40     }
41 
42     /** {@inheritDoc} */
43     @Override
allocateRegisters()44     public RegisterMapper allocateRegisters() {
45         int oldRegCount = ssaMeth.getRegCount();
46 
47         BasicRegisterMapper mapper = new BasicRegisterMapper(oldRegCount);
48 
49         for (int i = 0; i < oldRegCount; i++) {
50             mapper.addMapping(i, i*2, 2);
51         }
52 
53         return mapper;
54     }
55 }
56