1 /* 2 * Copyright (c) 2013, 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; 24 25 import java.util.List; 26 27 import org.graalvm.compiler.core.common.cfg.AbstractBlockBase; 28 import org.graalvm.compiler.lir.StandardOp.ImplicitNullCheck; 29 import org.graalvm.compiler.lir.StandardOp.NullCheck; 30 import org.graalvm.compiler.lir.gen.LIRGenerationResult; 31 import org.graalvm.compiler.lir.phases.PostAllocationOptimizationPhase; 32 33 import jdk.vm.ci.code.TargetDescription; 34 35 public final class NullCheckOptimizer extends PostAllocationOptimizationPhase { 36 37 @Override 38 protected void run(TargetDescription target, LIRGenerationResult lirGenRes, PostAllocationOptimizationContext context) { 39 LIR ir = lirGenRes.getLIR(); 40 AbstractBlockBase<?>[] blocks = ir.codeEmittingOrder(); 41 NullCheckOptimizer.foldNullChecks(ir, blocks, target.implicitNullCheckLimit); 42 } 43 44 private static void foldNullChecks(LIR ir, AbstractBlockBase<?>[] blocks, int implicitNullCheckLimit) { 45 for (AbstractBlockBase<?> block : blocks) { 46 if (block == null) { 47 continue; 48 } 49 List<LIRInstruction> list = ir.getLIRforBlock(block); 50 51 if (!list.isEmpty()) { 52 53 LIRInstruction lastInstruction = list.get(0); 54 for (int i = 0; i < list.size(); i++) { 55 LIRInstruction instruction = list.get(i); 56 57 if (instruction instanceof ImplicitNullCheck && lastInstruction instanceof NullCheck) { 58 NullCheck nullCheck = (NullCheck) lastInstruction; 59 ImplicitNullCheck implicitNullCheck = (ImplicitNullCheck) instruction; 60 if (implicitNullCheck.makeNullCheckFor(nullCheck.getCheckedValue(), nullCheck.getState(), implicitNullCheckLimit)) { 61 list.remove(i - 1); 62 if (i < list.size()) { 63 instruction = list.get(i); 64 } 65 } 66 } 67 lastInstruction = instruction; 68 } 69 } 70 } 71 } 72 73 }