1 /* 2 * Copyright (c) 2013, 2018, 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 24 25 package org.graalvm.compiler.hotspot; 26 27 import static org.graalvm.compiler.lir.LIRInstruction.OperandFlag.STACK; 28 29 import java.util.Arrays; 30 31 import org.graalvm.compiler.core.common.LIRKind; 32 import org.graalvm.compiler.lir.LIRInstruction; 33 import org.graalvm.compiler.lir.LIRInstructionClass; 34 import org.graalvm.compiler.lir.VirtualStackSlot; 35 import org.graalvm.compiler.lir.asm.CompilationResultBuilder; 36 import org.graalvm.compiler.lir.framemap.FrameMapBuilder; 37 38 import jdk.vm.ci.meta.AllocatableValue; 39 40 /** 41 * Manages allocation and re-use of lock slots in a scoped manner. The slots are used in HotSpot's 42 * lightweight locking mechanism to store the mark word of an object being locked. 43 */ 44 public class HotSpotLockStack extends LIRInstruction { 45 public static final LIRInstructionClass<HotSpotLockStack> TYPE = LIRInstructionClass.create(HotSpotLockStack.class); 46 private static final AllocatableValue[] EMPTY = new AllocatableValue[0]; 47 48 @Def({STACK}) private AllocatableValue[] locks; 49 private final FrameMapBuilder frameMapBuilder; 50 private final LIRKind slotKind; 51 HotSpotLockStack(FrameMapBuilder frameMapBuilder, LIRKind slotKind)52 public HotSpotLockStack(FrameMapBuilder frameMapBuilder, LIRKind slotKind) { 53 super(TYPE); 54 this.frameMapBuilder = frameMapBuilder; 55 this.slotKind = slotKind; 56 this.locks = EMPTY; 57 } 58 59 /** 60 * Gets a stack slot for a lock at a given lock nesting depth, allocating it first if necessary. 61 */ makeLockSlot(int lockDepth)62 public VirtualStackSlot makeLockSlot(int lockDepth) { 63 if (locks == EMPTY) { 64 locks = new AllocatableValue[lockDepth + 1]; 65 } else if (locks.length < lockDepth + 1) { 66 locks = Arrays.copyOf(locks, lockDepth + 1); 67 } 68 if (locks[lockDepth] == null) { 69 locks[lockDepth] = frameMapBuilder.allocateSpillSlot(slotKind); 70 } 71 return (VirtualStackSlot) locks[lockDepth]; 72 } 73 74 @Override emitCode(CompilationResultBuilder crb)75 public void emitCode(CompilationResultBuilder crb) { 76 // do nothing 77 } 78 } 79