88 lines
3.5 KiB
Java
88 lines
3.5 KiB
Java
/*******************************************************************************
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* Copyright (c) 2013 IBM Corporation.
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* All rights reserved. This program and the accompanying materials
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* are made available under the terms of the Eclipse Public License v1.0
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* which accompanies this distribution, and is available at
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* http://www.eclipse.org/legal/epl-v10.html
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*
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* Contributors:
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* IBM Corporation - initial API and implementation
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*******************************************************************************/
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package com.ibm.wala.cast.ir.translator;
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import java.util.Map;
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import com.ibm.wala.cast.tree.CAst;
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import com.ibm.wala.cast.tree.CAstControlFlowMap;
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import com.ibm.wala.cast.tree.CAstNode;
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import com.ibm.wala.cast.tree.impl.CAstOperator;
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import com.ibm.wala.cast.tree.rewrite.CAstBasicRewriter;
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import com.ibm.wala.cast.tree.rewrite.CAstBasicRewriter.NonCopyingContext;
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import com.ibm.wala.util.collections.Pair;
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public abstract class ConstantFoldingRewriter extends CAstBasicRewriter<NonCopyingContext> {
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protected ConstantFoldingRewriter(CAst Ast) {
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super(Ast, new NonCopyingContext(), true);
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}
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protected abstract Object eval(CAstOperator op, Object lhs, Object rhs);
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@Override
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protected CAstNode copyNodes(CAstNode root,
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CAstControlFlowMap cfg,
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NonCopyingContext context,
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Map<Pair<CAstNode, NoKey>, CAstNode> nodeMap)
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{
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CAstNode result;
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if (root.getKind() == CAstNode.BINARY_EXPR) {
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CAstNode left = copyNodes(root.getChild(1), cfg, context, nodeMap);
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CAstNode right = copyNodes(root.getChild(2), cfg, context, nodeMap);
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Object v;
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if (left.getKind() == CAstNode.CONSTANT && right.getKind() == CAstNode.CONSTANT && (v = eval((CAstOperator) root.getChild(0), left.getValue(), right.getValue())) != null) {
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result = Ast.makeConstant(v);
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} else {
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result = Ast.makeNode(CAstNode.BINARY_EXPR, root.getChild(0), left, right);
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}
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} else if (root.getKind() == CAstNode.IF_EXPR || root.getKind() == CAstNode.IF_STMT) {
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CAstNode expr = copyNodes(root.getChild(0), cfg, context, nodeMap);
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if (expr.getKind() == CAstNode.CONSTANT && expr.getValue() == Boolean.TRUE) {
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result = copyNodes(root.getChild(1), cfg, context, nodeMap);
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} else if (expr.getKind() == CAstNode.CONSTANT && root.getChildCount() > 2 && expr.getValue() == Boolean.FALSE) {
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result = copyNodes(root.getChild(2), cfg, context, nodeMap);
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} else {
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CAstNode then = copyNodes(root.getChild(1), cfg, context, nodeMap);
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if (root.getChildCount() == 3) {
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result = Ast.makeNode(root.getKind(), expr, then, copyNodes(root.getChild(2), cfg, context, nodeMap));
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} else {
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result = Ast.makeNode(root.getKind(), expr, then);
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}
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}
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} else if (root.getKind() == CAstNode.CONSTANT) {
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result = Ast.makeConstant(root.getValue());
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} else if (root.getKind() == CAstNode.OPERATOR) {
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result = root;
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} else {
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CAstNode children[] = new CAstNode[root.getChildCount()];
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for (int i = 0; i < children.length; i++) {
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children[i] = copyNodes(root.getChild(i), cfg, context, nodeMap);
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}
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for(Object label: cfg.getTargetLabels(root)) {
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if (label instanceof CAstNode) {
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copyNodes((CAstNode)label, cfg, context, nodeMap);
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}
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}
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CAstNode copy = Ast.makeNode(root.getKind(), children);
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result = copy;
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}
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nodeMap.put(Pair.make(root, context.key()), result);
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return result;
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}
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}
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