1 /*
2  * Copyright (C) 2008 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;
18 
19 import com.android.dx.util.BitIntSet;
20 import com.android.dx.util.IntSet;
21 import com.android.dx.util.ListIntSet;
22 
23 
24 /**
25  * Makes int sets for various parts of the optimizer.
26  */
27 public final class SetFactory {
28 
29     /**
30      * BitIntSet/ListIntSet threshold for dominance frontier sets. These
31      * sets are kept per basic block until phi placement and tend to be,
32      * like the CFG itself, very sparse at large sizes.
33      *
34      * A value of 3072 here is somewhere around 1.125mb of total bitset size.
35      */
36     private static final int DOMFRONT_SET_THRESHOLD_SIZE = 3072;
37 
38     /**
39      * BitIntSet/ListIntSet threshold for interference graph sets. These
40      * sets are kept per register until register allocation is done.
41      *
42      * A value of 3072 here is somewhere around 1.125mb of total bitset size.
43      */
44     private static final int INTERFERENCE_SET_THRESHOLD_SIZE = 3072;
45 
46     /**
47      * BitIntSet/ListIntSet threshold for the live in/out sets kept by
48      * {@link SsaBasicBlock}. These are sets of SSA registers kept per basic
49      * block during register allocation.
50      *
51      * The total size of a bitset for this would be the count of blocks
52      * times the size of registers. The threshold value here is merely
53      * the register count, which is typically on the order of the block
54      * count as well.
55      */
56     private static final int LIVENESS_SET_THRESHOLD_SIZE = 3072;
57 
58 
59     /**
60      * Make IntSet for the dominance-frontier sets.
61      *
62      * @param szBlocks {@code >=0;} count of basic blocks in method
63      * @return {@code non-null;} appropriate set
64      */
makeDomFrontSet(int szBlocks)65     /*package*/ static IntSet makeDomFrontSet(int szBlocks) {
66         return szBlocks <= DOMFRONT_SET_THRESHOLD_SIZE
67                 ? new BitIntSet(szBlocks)
68                 : new ListIntSet();
69     }
70 
71     /**
72      * Make IntSet for the interference graph sets. Public because
73      * InterferenceGraph is in another package.
74      *
75      * @param countRegs {@code >=0;} count of SSA registers used in method
76      * @return {@code non-null;} appropriate set
77      */
makeInterferenceSet(int countRegs)78     public static IntSet makeInterferenceSet(int countRegs) {
79         return countRegs <= INTERFERENCE_SET_THRESHOLD_SIZE
80                 ? new BitIntSet(countRegs)
81                 : new ListIntSet();
82     }
83 
84     /**
85      * Make IntSet for register live in/out sets.
86      *
87      * @param countRegs {@code >=0;} count of SSA registers used in method
88      * @return {@code non-null;} appropriate set
89      */
makeLivenessSet(int countRegs)90     /*package*/ static IntSet makeLivenessSet(int countRegs) {
91         return countRegs <= LIVENESS_SET_THRESHOLD_SIZE
92                 ? new BitIntSet(countRegs)
93                 : new ListIntSet();
94     }
95 }
96