--- /dev/null 2017-01-22 10:16:57.869617664 -0800 +++ new/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.lir/src/org/graalvm/compiler/lir/alloc/lsra/LinearScanEliminateSpillMovePhase.java 2017-02-15 17:05:27.709591229 -0800 @@ -0,0 +1,231 @@ +/* + * Copyright (c) 2015, 2015, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + */ +package org.graalvm.compiler.lir.alloc.lsra; + +import static org.graalvm.compiler.core.common.GraalOptions.DetailedAsserts; +import static org.graalvm.compiler.lir.LIRValueUtil.isStackSlotValue; +import static org.graalvm.compiler.lir.LIRValueUtil.isVariable; +import static org.graalvm.compiler.lir.phases.LIRPhase.Options.LIROptimization; +import static jdk.vm.ci.code.ValueUtil.isRegister; + +import java.util.List; + +import org.graalvm.compiler.core.common.cfg.AbstractBlockBase; +import org.graalvm.compiler.debug.Debug; +import org.graalvm.compiler.debug.Indent; +import org.graalvm.compiler.lir.LIRInsertionBuffer; +import org.graalvm.compiler.lir.LIRInstruction; +import org.graalvm.compiler.lir.StandardOp.LoadConstantOp; +import org.graalvm.compiler.lir.StandardOp.MoveOp; +import org.graalvm.compiler.lir.StandardOp.ValueMoveOp; +import org.graalvm.compiler.lir.alloc.lsra.Interval.SpillState; +import org.graalvm.compiler.lir.alloc.lsra.LinearScan.IntervalPredicate; +import org.graalvm.compiler.lir.gen.LIRGenerationResult; +import org.graalvm.compiler.lir.phases.AllocationPhase; +import org.graalvm.compiler.options.NestedBooleanOptionValue; +import org.graalvm.compiler.options.Option; +import org.graalvm.compiler.options.OptionType; +import org.graalvm.compiler.options.OptionValue; + +import jdk.vm.ci.code.TargetDescription; +import jdk.vm.ci.meta.AllocatableValue; + +public class LinearScanEliminateSpillMovePhase extends AllocationPhase { + + public static class Options { + // @formatter:off + @Option(help = "Enable spill move elimination.", type = OptionType.Debug) + public static final OptionValue LIROptLSRAEliminateSpillMoves = new NestedBooleanOptionValue(LIROptimization, true); + // @formatter:on + } + + private static final IntervalPredicate mustStoreAtDefinition = new LinearScan.IntervalPredicate() { + + @Override + public boolean apply(Interval i) { + return i.isSplitParent() && i.spillState() == SpillState.StoreAtDefinition; + } + }; + + protected final LinearScan allocator; + + protected LinearScanEliminateSpillMovePhase(LinearScan allocator) { + this.allocator = allocator; + } + + @Override + protected void run(TargetDescription target, LIRGenerationResult lirGenRes, AllocationContext context) { + eliminateSpillMoves(); + } + + /** + * @return the index of the first instruction that is of interest for + * {@link #eliminateSpillMoves()} + */ + protected int firstInstructionOfInterest() { + // skip the first because it is always a label + return 1; + } + + // called once before assignment of register numbers + @SuppressWarnings("try") + void eliminateSpillMoves() { + try (Indent indent = Debug.logAndIndent("Eliminating unnecessary spill moves")) { + + /* + * collect all intervals that must be stored after their definition. The list is sorted + * by Interval.spillDefinitionPos. + */ + Interval interval; + interval = allocator.createUnhandledLists(mustStoreAtDefinition, null).first; + if (DetailedAsserts.getValue()) { + checkIntervals(interval); + } + + LIRInsertionBuffer insertionBuffer = new LIRInsertionBuffer(); + for (AbstractBlockBase block : allocator.sortedBlocks()) { + try (Indent indent1 = Debug.logAndIndent("Handle %s", block)) { + List instructions = allocator.getLIR().getLIRforBlock(block); + int numInst = instructions.size(); + + // iterate all instructions of the block. + for (int j = firstInstructionOfInterest(); j < numInst; j++) { + LIRInstruction op = instructions.get(j); + int opId = op.id(); + + if (opId == -1) { + MoveOp move = (MoveOp) op; + /* + * Remove move from register to stack if the stack slot is guaranteed to + * be correct. Only moves that have been inserted by LinearScan can be + * removed. + */ + if (Options.LIROptLSRAEliminateSpillMoves.getValue() && canEliminateSpillMove(block, move)) { + /* + * Move target is a stack slot that is always correct, so eliminate + * instruction. + */ + if (Debug.isLogEnabled()) { + if (move instanceof ValueMoveOp) { + ValueMoveOp vmove = (ValueMoveOp) move; + Debug.log("eliminating move from interval %d (%s) to %d (%s) in block %s", allocator.operandNumber(vmove.getInput()), vmove.getInput(), + allocator.operandNumber(vmove.getResult()), vmove.getResult(), block); + } else { + LoadConstantOp load = (LoadConstantOp) move; + Debug.log("eliminating constant load from %s to %d (%s) in block %s", load.getConstant(), allocator.operandNumber(load.getResult()), load.getResult(), block); + } + } + + // null-instructions are deleted by assignRegNum + instructions.set(j, null); + } + + } else { + /* + * Insert move from register to stack just after the beginning of the + * interval. + */ + assert interval == Interval.EndMarker || interval.spillDefinitionPos() >= opId : "invalid order"; + assert interval == Interval.EndMarker || (interval.isSplitParent() && interval.spillState() == SpillState.StoreAtDefinition) : "invalid interval"; + + while (interval != Interval.EndMarker && interval.spillDefinitionPos() == opId) { + if (!interval.canMaterialize()) { + if (!insertionBuffer.initialized()) { + /* + * prepare insertion buffer (appended when all instructions + * in the block are processed) + */ + insertionBuffer.init(instructions); + } + + AllocatableValue fromLocation = interval.location(); + AllocatableValue toLocation = LinearScan.canonicalSpillOpr(interval); + if (!fromLocation.equals(toLocation)) { + + assert isRegister(fromLocation) : "from operand must be a register but is: " + fromLocation + " toLocation=" + toLocation + " spillState=" + + interval.spillState(); + assert isStackSlotValue(toLocation) : "to operand must be a stack slot"; + + LIRInstruction move = allocator.getSpillMoveFactory().createMove(toLocation, fromLocation); + insertionBuffer.append(j + 1, move); + + if (Debug.isLogEnabled()) { + Debug.log("inserting move after definition of interval %d to stack slot %s at opId %d", interval.operandNumber, interval.spillSlot(), opId); + } + } + } + interval = interval.next; + } + } + } // end of instruction iteration + + if (insertionBuffer.initialized()) { + insertionBuffer.finish(); + } + } + } // end of block iteration + + assert interval == Interval.EndMarker : "missed an interval"; + } + } + + /** + * @param block The block {@code move} is located in. + * @param move Spill move. + */ + protected boolean canEliminateSpillMove(AbstractBlockBase block, MoveOp move) { + assert isVariable(move.getResult()) : "LinearScan inserts only moves to variables: " + move; + + Interval curInterval = allocator.intervalFor(move.getResult()); + + if (!isRegister(curInterval.location()) && curInterval.alwaysInMemory()) { + assert isStackSlotValue(curInterval.location()) : "Not a stack slot: " + curInterval.location(); + return true; + } + return false; + } + + private static void checkIntervals(Interval interval) { + Interval prev = null; + Interval temp = interval; + while (temp != Interval.EndMarker) { + assert temp.spillDefinitionPos() > 0 : "invalid spill definition pos"; + if (prev != null) { + assert temp.from() >= prev.from() : "intervals not sorted"; + assert temp.spillDefinitionPos() >= prev.spillDefinitionPos() : "when intervals are sorted by from : then they must also be sorted by spillDefinitionPos"; + } + + assert temp.spillSlot() != null || temp.canMaterialize() : "interval has no spill slot assigned"; + assert temp.spillDefinitionPos() >= temp.from() : "invalid order"; + assert temp.spillDefinitionPos() <= temp.from() + 2 : "only intervals defined once at their start-pos can be optimized"; + + if (Debug.isLogEnabled()) { + Debug.log("interval %d (from %d to %d) must be stored at %d", temp.operandNumber, temp.from(), temp.to(), temp.spillDefinitionPos()); + } + + prev = temp; + temp = temp.next; + } + } + +}