1 /* 2 * Copyright (c) 2015, 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.alloc.lsra.ssa; 24 25 import static org.graalvm.compiler.lir.LIRValueUtil.isStackSlotValue; 26 import static jdk.vm.ci.code.ValueUtil.isRegister; 27 28 import org.graalvm.compiler.core.common.cfg.AbstractBlockBase; 29 import org.graalvm.compiler.debug.Debug; 30 import org.graalvm.compiler.debug.Indent; 31 import org.graalvm.compiler.lir.LIRInstruction; 32 import org.graalvm.compiler.lir.StandardOp.LabelOp; 33 import org.graalvm.compiler.lir.StandardOp.MoveOp; 34 import org.graalvm.compiler.lir.alloc.lsra.Interval; 35 import org.graalvm.compiler.lir.alloc.lsra.LinearScan; 36 import org.graalvm.compiler.lir.alloc.lsra.LinearScanEliminateSpillMovePhase; 37 38 public class SSALinearScanEliminateSpillMovePhase extends LinearScanEliminateSpillMovePhase { 39 40 SSALinearScanEliminateSpillMovePhase(LinearScan allocator) { 41 super(allocator); 42 } 43 44 @Override 45 protected int firstInstructionOfInterest() { 46 // also look at Labels as they define PHI values 47 return 0; 48 } 49 50 @Override 51 protected boolean canEliminateSpillMove(AbstractBlockBase<?> block, MoveOp move) { 52 if (super.canEliminateSpillMove(block, move)) { 53 // SSA Linear Scan might introduce moves to stack slots 54 Interval curInterval = allocator.intervalFor(move.getResult()); 55 assert !isRegister(curInterval.location()) && curInterval.alwaysInMemory(); 56 if (!isPhiResolutionMove(block, move, curInterval)) { 57 assert isStackSlotValue(curInterval.location()) : "Not a stack slot: " + curInterval.location(); 58 return true; 59 } 60 } 61 return false; 62 } 63 64 @SuppressWarnings("try") 65 private boolean isPhiResolutionMove(AbstractBlockBase<?> block, MoveOp move, Interval toInterval) { 66 if (!toInterval.isSplitParent()) { 67 return false; 68 } 69 if ((toInterval.from() & 1) == 1) { 70 // phi intervals start at even positions. 71 return false; 72 } 73 if (block.getSuccessorCount() != 1) { 74 return false; 75 } 76 LIRInstruction op = allocator.instructionForId(toInterval.from()); 77 if (!(op instanceof LabelOp)) { 78 return false; 79 } 80 AbstractBlockBase<?> intStartBlock = allocator.blockForId(toInterval.from()); 81 assert allocator.getLIR().getLIRforBlock(intStartBlock).get(0).equals(op); 82 if (!block.getSuccessors()[0].equals(intStartBlock)) { 83 return false; 84 } 85 try (Indent indet = Debug.indent()) { 86 Debug.log("Is a move (%s) to phi interval %s", move, toInterval); 87 } 88 return true; 89 } 90 }