| /* |
| * Copyright (c) 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. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * 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 jdk.nashorn.internal.codegen; |
| |
| import java.util.ArrayDeque; |
| import java.util.Collections; |
| import java.util.Deque; |
| import jdk.nashorn.internal.ir.FunctionNode; |
| import jdk.nashorn.internal.ir.Node; |
| import jdk.nashorn.internal.ir.Statement; |
| import jdk.nashorn.internal.ir.visitor.SimpleNodeVisitor; |
| import jdk.nashorn.internal.runtime.RecompilableScriptFunctionData; |
| |
| class CacheAst extends SimpleNodeVisitor { |
| private final Deque<RecompilableScriptFunctionData> dataStack = new ArrayDeque<>(); |
| |
| private final Compiler compiler; |
| |
| CacheAst(final Compiler compiler) { |
| this.compiler = compiler; |
| assert !compiler.isOnDemandCompilation(); |
| } |
| |
| @Override |
| public boolean enterFunctionNode(final FunctionNode functionNode) { |
| final int id = functionNode.getId(); |
| // It isn't necessary to keep a stack of RecompilableScriptFunctionData, but then we'd need to do a |
| // potentially transitive lookup with compiler.getScriptFunctionData(id) for deeper functions; this way |
| // we keep it constant time. |
| dataStack.push(dataStack.isEmpty() ? compiler.getScriptFunctionData(id) : dataStack.peek().getScriptFunctionData(id)); |
| return true; |
| } |
| |
| @Override |
| public Node leaveFunctionNode(final FunctionNode functionNode) { |
| final RecompilableScriptFunctionData data = dataStack.pop(); |
| if (functionNode.isSplit()) { |
| // NOTE: cache only split function ASTs from eager pass. Caching non-split functions would require |
| // some additional work, namely creating the concept of "uncacheable" function and reworking |
| // ApplySpecialization to ensure that functions undergoing apply-to-call transformations are not |
| // cacheable as well as recomputing Symbol.useCount when caching the eagerly parsed AST. |
| // Recomputing Symbol.useCount would be needed so it will only reflect uses from within the |
| // function being cached (and not reflect uses from its own nested functions or functions it is |
| // nested in). This is consistent with the count an on-demand recompilation of the function would |
| // produce. This is important as the decision to emit shared scope calls is based on this count, |
| // and if it is not matched between a previous version of the code and its deoptimizing rest-of |
| // compilation, it can result in rest-of not emitting a shared scope call where a previous version |
| // of the code (compiled from a cached eager pre-pass seeing higher (global) useCount) would emit |
| // it, causing a mismatch in stack shapes between previous code and its rest-of. |
| data.setCachedAst(functionNode); |
| } |
| |
| if (!dataStack.isEmpty() && ((dataStack.peek().getFunctionFlags() & FunctionNode.IS_SPLIT) != 0)) { |
| // Return a function node with no body so that caching outer functions doesn't hold on to nested |
| // functions' bodies. Note we're doing this only for functions directly nested inside split |
| // functions, since we're only caching the split ones. It is not necessary to limit body removal |
| // to just these functions, but it's a cheap way to prevent unnecessary AST mutations. |
| return functionNode.setBody(lc, functionNode.getBody().setStatements(null, Collections.<Statement>emptyList())); |
| } |
| return functionNode; |
| } |
| } |