RegisterAttributes.java revision 12651:6ef01bd40ce2 
1/*
2 * Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23package jdk.vm.ci.code;
24
25import java.util.Arrays;
26import java.util.Collections;
27import java.util.List;
28
29/**
30 * A collection of register attributes. The specific attribute values for a register may be local to
31 * a compilation context. For example, a {@link RegisterConfig} in use during a compilation will
32 * determine which registers are callee saved.
33 */
34public class RegisterAttributes {
35
36    private final boolean callerSave;
37    private final boolean calleeSave;
38    private final boolean allocatable;
39
40    public RegisterAttributes(boolean isCallerSave, boolean isCalleeSave, boolean isAllocatable) {
41        this.callerSave = isCallerSave;
42        this.calleeSave = isCalleeSave;
43        this.allocatable = isAllocatable;
44    }
45
46    public static final RegisterAttributes NONE = new RegisterAttributes(false, false, false);
47
48    /**
49     * Creates a map from register {@linkplain Register#number numbers} to register
50     * {@linkplain RegisterAttributes attributes} for a given register configuration and set of
51     * registers.
52     *
53     * @param registerConfig a register configuration
54     * @param registers a set of registers
55     * @return an array whose length is the max register number in {@code registers} plus 1. An
56     *         element at index i holds the attributes of the register whose number is i.
57     */
58    public static RegisterAttributes[] createMap(RegisterConfig registerConfig, RegisterArray registers) {
59        RegisterAttributes[] map = new RegisterAttributes[registers.size()];
60        List<Register> callerSaveRegisters = registerConfig.getCallerSaveRegisters().asList();
61        List<Register> calleeSaveRegisters = registerConfig.getCalleeSaveRegisters() == null ? Collections.emptyList() : registerConfig.getCalleeSaveRegisters().asList();
62        List<Register> allocatableRegisters = registerConfig.getAllocatableRegisters().asList();
63        for (Register reg : registers) {
64            if (reg != null) {
65                RegisterAttributes attr = new RegisterAttributes(callerSaveRegisters.contains(reg), calleeSaveRegisters.contains(reg), allocatableRegisters.contains(reg));
66                if (map.length <= reg.number) {
67                    map = Arrays.copyOf(map, reg.number + 1);
68                }
69                map[reg.number] = attr;
70            }
71        }
72        for (int i = 0; i < map.length; i++) {
73            if (map[i] == null) {
74                map[i] = NONE;
75            }
76        }
77        return map;
78    }
79
80    /**
81     * @return {@code true} if a register is available for use by a register allocator otherwise
82     *         {@code false}
83     */
84    public boolean isAllocatable() {
85        return allocatable;
86    }
87
88    /**
89     * @return {@code true} if a register whose value preservation (if required) across a call is
90     *         the responsibility of the callee otherwise {@code false}
91     */
92    public boolean isCalleeSave() {
93        return calleeSave;
94    }
95
96    /**
97     * @return {@code true} if a register whose value preservation (if required) across a call is
98     *         the responsibility of the caller otherwise {@code false}
99     */
100    public boolean isCallerSave() {
101        return callerSave;
102    }
103}
104