--- /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/LinearScanResolveDataFlowPhase.java 2017-02-15 17:05:29.684677919 -0800 @@ -0,0 +1,210 @@ +/* + * 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 java.util.BitSet; +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.LIRInstruction; +import org.graalvm.compiler.lir.StandardOp; +import org.graalvm.compiler.lir.gen.LIRGenerationResult; +import org.graalvm.compiler.lir.phases.AllocationPhase; + +import jdk.vm.ci.code.TargetDescription; + +/** + * Phase 6: resolve data flow + * + * Insert moves at edges between blocks if intervals have been split. + */ +public class LinearScanResolveDataFlowPhase extends AllocationPhase { + + protected final LinearScan allocator; + + protected LinearScanResolveDataFlowPhase(LinearScan allocator) { + this.allocator = allocator; + } + + @Override + protected void run(TargetDescription target, LIRGenerationResult lirGenRes, AllocationContext context) { + resolveDataFlow(); + allocator.printIntervals("After resolve data flow"); + } + + protected void resolveCollectMappings(AbstractBlockBase fromBlock, AbstractBlockBase toBlock, AbstractBlockBase midBlock, MoveResolver moveResolver) { + assert moveResolver.checkEmpty(); + assert midBlock == null || + (midBlock.getPredecessorCount() == 1 && midBlock.getSuccessorCount() == 1 && midBlock.getPredecessors()[0].equals(fromBlock) && midBlock.getSuccessors()[0].equals( + toBlock)); + + int toBlockFirstInstructionId = allocator.getFirstLirInstructionId(toBlock); + int fromBlockLastInstructionId = allocator.getLastLirInstructionId(fromBlock) + 1; + int numOperands = allocator.operandSize(); + BitSet liveAtEdge = allocator.getBlockData(toBlock).liveIn; + + // visit all variables for which the liveAtEdge bit is set + for (int operandNum = liveAtEdge.nextSetBit(0); operandNum >= 0; operandNum = liveAtEdge.nextSetBit(operandNum + 1)) { + assert operandNum < numOperands : "live information set for not exisiting interval"; + assert allocator.getBlockData(fromBlock).liveOut.get(operandNum) && allocator.getBlockData(toBlock).liveIn.get(operandNum) : "interval not live at this edge"; + + Interval fromInterval = allocator.splitChildAtOpId(allocator.intervalFor(operandNum), fromBlockLastInstructionId, LIRInstruction.OperandMode.DEF); + Interval toInterval = allocator.splitChildAtOpId(allocator.intervalFor(operandNum), toBlockFirstInstructionId, LIRInstruction.OperandMode.DEF); + + if (fromInterval != toInterval && !fromInterval.location().equals(toInterval.location())) { + // need to insert move instruction + moveResolver.addMapping(fromInterval, toInterval); + } + } + } + + void resolveFindInsertPos(AbstractBlockBase fromBlock, AbstractBlockBase toBlock, MoveResolver moveResolver) { + if (fromBlock.getSuccessorCount() <= 1) { + if (Debug.isLogEnabled()) { + Debug.log("inserting moves at end of fromBlock B%d", fromBlock.getId()); + } + + List instructions = allocator.getLIR().getLIRforBlock(fromBlock); + LIRInstruction instr = instructions.get(instructions.size() - 1); + if (instr instanceof StandardOp.JumpOp) { + // insert moves before branch + moveResolver.setInsertPosition(instructions, instructions.size() - 1); + } else { + moveResolver.setInsertPosition(instructions, instructions.size()); + } + + } else { + if (Debug.isLogEnabled()) { + Debug.log("inserting moves at beginning of toBlock B%d", toBlock.getId()); + } + + if (DetailedAsserts.getValue()) { + assert allocator.getLIR().getLIRforBlock(fromBlock).get(0) instanceof StandardOp.LabelOp : "block does not start with a label"; + + /* + * Because the number of predecessor edges matches the number of successor edges, + * blocks which are reached by switch statements may have be more than one + * predecessor but it will be guaranteed that all predecessors will be the same. + */ + for (AbstractBlockBase predecessor : toBlock.getPredecessors()) { + assert fromBlock == predecessor : "all critical edges must be broken"; + } + } + + moveResolver.setInsertPosition(allocator.getLIR().getLIRforBlock(toBlock), 1); + } + } + + /** + * Inserts necessary moves (spilling or reloading) at edges between blocks for intervals that + * have been split. + */ + @SuppressWarnings("try") + protected void resolveDataFlow() { + try (Indent indent = Debug.logAndIndent("resolve data flow")) { + + MoveResolver moveResolver = allocator.createMoveResolver(); + BitSet blockCompleted = new BitSet(allocator.blockCount()); + + optimizeEmptyBlocks(moveResolver, blockCompleted); + + resolveDataFlow0(moveResolver, blockCompleted); + + } + } + + protected void optimizeEmptyBlocks(MoveResolver moveResolver, BitSet blockCompleted) { + for (AbstractBlockBase block : allocator.sortedBlocks()) { + + // check if block has only one predecessor and only one successor + if (block.getPredecessorCount() == 1 && block.getSuccessorCount() == 1) { + List instructions = allocator.getLIR().getLIRforBlock(block); + assert instructions.get(0) instanceof StandardOp.LabelOp : "block must start with label"; + assert instructions.get(instructions.size() - 1) instanceof StandardOp.JumpOp : "block with successor must end with unconditional jump"; + + // check if block is empty (only label and branch) + if (instructions.size() == 2) { + AbstractBlockBase pred = block.getPredecessors()[0]; + AbstractBlockBase sux = block.getSuccessors()[0]; + + // prevent optimization of two consecutive blocks + if (!blockCompleted.get(pred.getLinearScanNumber()) && !blockCompleted.get(sux.getLinearScanNumber())) { + if (Debug.isLogEnabled()) { + Debug.log(" optimizing empty block B%d (pred: B%d, sux: B%d)", block.getId(), pred.getId(), sux.getId()); + } + + blockCompleted.set(block.getLinearScanNumber()); + + /* + * Directly resolve between pred and sux (without looking at the empty block + * between). + */ + resolveCollectMappings(pred, sux, block, moveResolver); + if (moveResolver.hasMappings()) { + moveResolver.setInsertPosition(instructions, 1); + moveResolver.resolveAndAppendMoves(); + } + } + } + } + } + } + + protected void resolveDataFlow0(MoveResolver moveResolver, BitSet blockCompleted) { + BitSet alreadyResolved = new BitSet(allocator.blockCount()); + for (AbstractBlockBase fromBlock : allocator.sortedBlocks()) { + if (!blockCompleted.get(fromBlock.getLinearScanNumber())) { + alreadyResolved.clear(); + alreadyResolved.or(blockCompleted); + + for (AbstractBlockBase toBlock : fromBlock.getSuccessors()) { + + /* + * Check for duplicate edges between the same blocks (can happen with switch + * blocks). + */ + if (!alreadyResolved.get(toBlock.getLinearScanNumber())) { + if (Debug.isLogEnabled()) { + Debug.log("processing edge between B%d and B%d", fromBlock.getId(), toBlock.getId()); + } + + alreadyResolved.set(toBlock.getLinearScanNumber()); + + // collect all intervals that have been split between + // fromBlock and toBlock + resolveCollectMappings(fromBlock, toBlock, null, moveResolver); + if (moveResolver.hasMappings()) { + resolveFindInsertPos(fromBlock, toBlock, moveResolver); + moveResolver.resolveAndAppendMoves(); + } + } + } + } + } + } + +}