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  */
  23 package jdk.vm.ci.code;
  24 
  25 import java.util.*;
  26 
  27 /**
  28  * A collection of register attributes. The specific attribute values for a register may be local to
  29  * a compilation context. For example, a {@link RegisterConfig} in use during a compilation will
  30  * determine which registers are callee saved.
  31  */
  32 public class RegisterAttributes {
  33 
  34     private final boolean callerSave;
  35     private final boolean calleeSave;
  36     private final boolean allocatable;
  37 
  38     public RegisterAttributes(boolean isCallerSave, boolean isCalleeSave, boolean isAllocatable) {
  39         this.callerSave = isCallerSave;
  40         this.calleeSave = isCalleeSave;
  41         this.allocatable = isAllocatable;
  42     }
  43 
  44     public static final RegisterAttributes NONE = new RegisterAttributes(false, false, false);
  45 
  46     /**
  47      * Creates a map from register {@linkplain Register#number numbers} to register
  48      * {@linkplain RegisterAttributes attributes} for a given register configuration and set of
  49      * registers.
  50      *
  51      * @param registerConfig a register configuration
  52      * @param registers a set of registers
  53      * @return an array whose length is the max register number in {@code registers} plus 1. An
  54      *         element at index i holds the attributes of the register whose number is i.
  55      */
  56     public static RegisterAttributes[] createMap(RegisterConfig registerConfig, Register[] registers) {
  57         RegisterAttributes[] map = new RegisterAttributes[registers.length];
  58         for (Register reg : registers) {
  59             if (reg != null) {
  60                 Register[] csr = registerConfig.getCalleeSaveRegisters();
  61                 RegisterAttributes attr = new RegisterAttributes(Arrays.asList(registerConfig.getCallerSaveRegisters()).contains(reg), csr == null ? false : Arrays.asList(csr).contains(reg),
  62                                 Arrays.asList(registerConfig.getAllocatableRegisters()).contains(reg));
  63                 if (map.length <= reg.number) {
  64                     map = Arrays.copyOf(map, reg.number + 1);
  65                 }
  66                 map[reg.number] = attr;
  67             }
  68         }
  69         for (int i = 0; i < map.length; i++) {
  70             if (map[i] == null) {
  71                 map[i] = NONE;
  72             }
  73         }
  74         return map;
  75     }
  76 
  77     /**
  78      * @return Denotes a register that is available for use by a register allocator.
  79      */
  80     public boolean isAllocatable() {
  81         return allocatable;
  82     }
  83 
  84     /**
  85      * @return Denotes a register whose value preservation (if required) across a call is the
  86      *         responsibility of the callee.
  87      */
  88     public boolean isCalleeSave() {
  89         return calleeSave;
  90     }
  91 
  92     /**
  93      * @return Denotes a register whose value preservation (if required) across a call is the
  94      *         responsibility of the caller.
  95      */
  96     public boolean isCallerSave() {
  97         return callerSave;
  98     }
  99 }