Mercurial > hg > graal-jvmci-8
diff graal/Compiler/src/com/sun/c1x/gen/PhiResolver.java @ 2507:9ec15d6914ca
Pull over of compiler from maxine repository.
author | Thomas Wuerthinger <thomas@wuerthinger.net> |
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date | Wed, 27 Apr 2011 11:43:22 +0200 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/graal/Compiler/src/com/sun/c1x/gen/PhiResolver.java Wed Apr 27 11:43:22 2011 +0200 @@ -0,0 +1,238 @@ +/* + * Copyright (c) 2009, 2010, 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 com.sun.c1x.gen; + +import static com.sun.cri.ci.CiValue.*; + +import java.util.*; + +import com.sun.c1x.ir.*; +import com.sun.cri.ci.*; + +/** + * Converts {@link Phi} instructions into moves. + * + * Resolves cycles: + * <pre> + * + * r1 := r2 becomes temp := r1 + * r2 := r1 r1 := r2 + * r2 := temp + * </pre> + * + * and orders moves: + * + * <pre> + * r2 := r3 becomes r1 := r2 + * r1 := r2 r2 := r3 + * </pre> + * + * @author Marcelo Cintra + * @author Thomas Wuerthinger + * @author Doug Simon + */ +public class PhiResolver { + + /** + * Tracks a data flow dependency between a source operand and any number of the destination operands. + */ + static class Node { + + /** + * A source operand whose value flows into the {@linkplain #destinations destination} operands. + */ + final CiValue operand; + + /** + * The operands whose values are defined by the {@linkplain #operand source} operand. + */ + final ArrayList<Node> destinations; + + /** + * Denotes if a move instruction has already been emitted to initialize the value of {@link #operand}. + */ + boolean assigned; + + /** + * Specifies if this operand been visited for the purpose of emitting a move instruction. + */ + boolean visited; + + /** + * Specifies if this is the initial definition in data flow path for a given value. + */ + boolean startNode; + + Node(CiValue operand) { + this.operand = operand; + destinations = new ArrayList<Node>(4); + } + + @Override + public String toString() { + StringBuilder buf = new StringBuilder(operand.toString()); + if (!destinations.isEmpty()) { + buf.append(" ->"); + for (Node node : destinations) { + buf.append(' ').append(node.operand); + } + } + return buf.toString(); + } + } + + private final LIRGenerator gen; + + /** + * The operand loop header phi for the operand currently being process in {@link #dispose()}. + */ + private Node loop; + + private CiValue temp; + + private final ArrayList<Node> variableOperands = new ArrayList<Node>(3); + private final ArrayList<Node> otherOperands = new ArrayList<Node>(3); + + /** + * Maps operands to nodes. + */ + private final HashMap<CiValue, Node> operandToNodeMap = new HashMap<CiValue, Node>(); + + public PhiResolver(LIRGenerator gen) { + this.gen = gen; + temp = IllegalValue; + } + + public void dispose() { + // resolve any cycles in moves from and to variables + for (int i = variableOperands.size() - 1; i >= 0; i--) { + Node node = variableOperands.get(i); + if (!node.visited) { + loop = null; + move(null, node); + node.startNode = true; + assert temp.isIllegal() : "moveTempTo() call missing"; + } + } + + // generate move for move from non variable to arbitrary destination + for (int i = otherOperands.size() - 1; i >= 0; i--) { + Node node = otherOperands.get(i); + for (int j = node.destinations.size() - 1; j >= 0; j--) { + emitMove(node.operand, node.destinations.get(j).operand); + } + } + } + + public void move(CiValue src, CiValue dest) { + assert dest.isVariable() : "destination must be virtual"; + // tty.print("move "); src.print(); tty.print(" to "); dest.print(); tty.cr(); + assert src.isLegal() : "source for phi move is illegal"; + assert dest.isLegal() : "destination for phi move is illegal"; + Node srcNode = sourceNode(src); + Node destNode = destinationNode(dest); + srcNode.destinations.add(destNode); + } + + private Node createNode(CiValue operand, boolean source) { + Node node; + if (operand.isVariable()) { + node = operandToNodeMap.get(operand); + assert node == null || node.operand.equals(operand); + if (node == null) { + node = new Node(operand); + operandToNodeMap.put(operand, node); + } + // Make sure that all variables show up in the list when + // they are used as the source of a move. + if (source) { + if (!variableOperands.contains(node)) { + variableOperands.add(node); + } + } + } else { + assert source; + node = new Node(operand); + otherOperands.add(node); + } + return node; + } + + private Node destinationNode(CiValue opr) { + return createNode(opr, false); + } + + private void emitMove(CiValue src, CiValue dest) { + assert src.isLegal(); + assert dest.isLegal(); + gen.lir.move(src, dest); + } + + // Traverse assignment graph in depth first order and generate moves in post order + // ie. two assignments: b := c, a := b start with node c: + // Call graph: move(NULL, c) -> move(c, b) -> move(b, a) + // Generates moves in this order: move b to a and move c to b + // ie. cycle a := b, b := a start with node a + // Call graph: move(NULL, a) -> move(a, b) -> move(b, a) + // Generates moves in this order: move b to temp, move a to b, move temp to a + private void move(Node src, Node dest) { + if (!dest.visited) { + dest.visited = true; + for (int i = dest.destinations.size() - 1; i >= 0; i--) { + move(dest, dest.destinations.get(i)); + } + } else if (!dest.startNode) { + // cycle in graph detected + assert loop == null : "only one loop valid!"; + loop = dest; + moveToTemp(src.operand); + return; + } // else dest is a start node + + if (!dest.assigned) { + if (loop == dest) { + moveTempTo(dest.operand); + dest.assigned = true; + } else if (src != null) { + emitMove(src.operand, dest.operand); + dest.assigned = true; + } + } + } + + private void moveTempTo(CiValue dest) { + assert temp.isLegal(); + emitMove(temp, dest); + temp = IllegalValue; + } + + private void moveToTemp(CiValue src) { + assert temp.isIllegal(); + temp = gen.newVariable(src.kind); + emitMove(src, temp); + } + + private Node sourceNode(CiValue opr) { + return createNode(opr, true); + } +}