1 /*
   2  * Copyright (c) 2013, 2015, 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 org.graalvm.compiler.lir.amd64;
  24 
  25 import static org.graalvm.compiler.lir.amd64.AMD64SaveRegistersOp.prune;
  26 
  27 import java.util.Set;
  28 
  29 import org.graalvm.compiler.asm.amd64.AMD64MacroAssembler;
  30 import org.graalvm.compiler.lir.LIRInstructionClass;
  31 import org.graalvm.compiler.lir.Opcode;
  32 import org.graalvm.compiler.lir.StandardOp.SaveRegistersOp;
  33 import org.graalvm.compiler.lir.asm.CompilationResultBuilder;
  34 import org.graalvm.compiler.lir.framemap.FrameMap;
  35 
  36 import jdk.vm.ci.code.Register;
  37 import jdk.vm.ci.code.RegisterSaveLayout;
  38 import jdk.vm.ci.meta.JavaConstant;
  39 
  40 /**
  41  * Writes well known garbage values to registers.
  42  */
  43 @Opcode("ZAP_REGISTER")
  44 public final class AMD64ZapRegistersOp extends AMD64LIRInstruction implements SaveRegistersOp {
  45     public static final LIRInstructionClass<AMD64ZapRegistersOp> TYPE = LIRInstructionClass.create(AMD64ZapRegistersOp.class);
  46 
  47     /**
  48      * The registers that are zapped.
  49      */
  50     protected final Register[] zappedRegisters;
  51 
  52     /**
  53      * The garbage values that are written to the registers.
  54      */
  55     protected final JavaConstant[] zapValues;
  56 
  57     public AMD64ZapRegistersOp(Register[] zappedRegisters, JavaConstant[] zapValues) {
  58         super(TYPE);
  59         this.zappedRegisters = zappedRegisters;
  60         this.zapValues = zapValues;
  61     }
  62 
  63     @Override
  64     public void emitCode(CompilationResultBuilder crb, AMD64MacroAssembler masm) {
  65         for (int i = 0; i < zappedRegisters.length; i++) {
  66             Register reg = zappedRegisters[i];
  67             if (reg != null) {
  68                 AMD64Move.const2reg(crb, masm, reg, zapValues[i]);
  69             }
  70         }
  71     }
  72 
  73     @Override
  74     public boolean supportsRemove() {
  75         return true;
  76     }
  77 
  78     @Override
  79     public int remove(Set<Register> doNotSave) {
  80         return prune(doNotSave, zappedRegisters);
  81     }
  82 
  83     @Override
  84     public RegisterSaveLayout getMap(FrameMap frameMap) {
  85         return new RegisterSaveLayout(new Register[0], new int[0]);
  86     }
  87 }