1 /*
   2  * Copyright (c) 2009, 2012, 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 static jdk.vm.ci.code.ValueUtil.isAllocatableValue;
  26 import static jdk.vm.ci.code.ValueUtil.isStackSlot;
  27 import jdk.vm.ci.meta.AllocatableValue;
  28 import jdk.vm.ci.meta.Value;
  29 
  30 /**
  31  * A calling convention describes the locations in which the arguments for a call are placed and the
  32  * location in which the return value is placed if the call is not void.
  33  */
  34 public class CallingConvention {
  35 
  36     /**
  37      * Marker interface denoting the type of a call for which a calling convention is requested.
  38      */
  39     public interface Type {
  40     }
  41 
  42     /**
  43      * The amount of stack space (in bytes) required for the stack-based arguments of the call.
  44      */
  45     private final int stackSize;
  46 
  47     private final AllocatableValue returnLocation;
  48 
  49     /**
  50      * The ordered locations in which the arguments are placed.
  51      */
  52     private final AllocatableValue[] argumentLocations;
  53 
  54     /**
  55      * Creates a description of the registers and stack locations used by a call.
  56      *
  57      * @param stackSize amount of stack space (in bytes) required for the stack-based arguments of
  58      *            the call
  59      * @param returnLocation the location for the return value or {@link Value#ILLEGAL} if a void
  60      *            call
  61      * @param argumentLocations the ordered locations in which the arguments are placed
  62      */
  63     public CallingConvention(int stackSize, AllocatableValue returnLocation, AllocatableValue... argumentLocations) {
  64         assert argumentLocations != null;
  65         assert returnLocation != null;
  66         this.argumentLocations = argumentLocations;
  67         this.stackSize = stackSize;
  68         this.returnLocation = returnLocation;
  69         assert verify();
  70     }
  71 
  72     /**
  73      * Gets the location for the return value or {@link Value#ILLEGAL} if a void call.
  74      */
  75     public AllocatableValue getReturn() {
  76         return returnLocation;
  77     }
  78 
  79     /**
  80      * Gets the location for the {@code index}'th argument.
  81      */
  82     public AllocatableValue getArgument(int index) {
  83         return argumentLocations[index];
  84     }
  85 
  86     /**
  87      * Gets the amount of stack space (in bytes) required for the stack-based arguments of the call.
  88      */
  89     public int getStackSize() {
  90         return stackSize;
  91     }
  92 
  93     /**
  94      * Gets the number of locations required for the arguments.
  95      */
  96     public int getArgumentCount() {
  97         return argumentLocations.length;
  98     }
  99 
 100     /**
 101      * Gets the locations required for the arguments.
 102      */
 103     @SuppressFBWarnings(value = "EI_EXPOSE_REP", justification = "FB false positive")
 104     public AllocatableValue[] getArguments() {
 105         if (argumentLocations.length == 0) {
 106             return argumentLocations;
 107         }
 108         return argumentLocations.clone();
 109     }
 110 
 111     @Override
 112     public String toString() {
 113         StringBuilder sb = new StringBuilder();
 114         sb.append("CallingConvention[");
 115         String sep = "";
 116         for (Value op : argumentLocations) {
 117             sb.append(sep).append(op);
 118             sep = ", ";
 119         }
 120         if (!returnLocation.equals(Value.ILLEGAL)) {
 121             sb.append(" -> ").append(returnLocation);
 122         }
 123         sb.append("]");
 124         return sb.toString();
 125     }
 126 
 127     private boolean verify() {
 128         for (int i = 0; i < argumentLocations.length; i++) {
 129             Value location = argumentLocations[i];
 130             assert isStackSlot(location) || isAllocatableValue(location);
 131         }
 132         return true;
 133     }
 134 }