/*
* Copyright 2007 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.gwt.dev.jjs.impl;
import com.google.gwt.dev.jjs.ast.Context;
import com.google.gwt.dev.jjs.ast.JClassType;
import com.google.gwt.dev.jjs.ast.JMethod;
import com.google.gwt.dev.jjs.ast.JMethodCall;
import com.google.gwt.dev.jjs.ast.JModVisitor;
import com.google.gwt.dev.jjs.ast.JNewInstance;
import com.google.gwt.dev.jjs.ast.JProgram;
import com.google.gwt.dev.jjs.ast.JRunAsync;
import com.google.gwt.dev.jjs.ast.JType;
import com.google.gwt.dev.util.log.speedtracer.CompilerEventType;
import com.google.gwt.dev.util.log.speedtracer.SpeedTracerLogger;
import com.google.gwt.dev.util.log.speedtracer.SpeedTracerLogger.Event;
/**
* Update polymorphic method calls to tighter bindings based on the type of the
* qualifier. For a given polymorphic method call to a non-final target, see if
* the static type of the qualifer would let us target an override instead.
*
* This is possible because the qualifier might have been tightened by
* {@link com.google.gwt.dev.jjs.impl.TypeTightener}.
*
* For example, given the code:
*
* <pre>
* List foo = new ArrayList<String>();
* foo.add("bar");
* </pre>
*
* The type of foo is tightened by TypeTightener from type List to be of type
* ArrayList. This means that MethodCallTightener can analyze the polymorphic
* call List.add() on foo and tighten it to the more specific ArrayList.add().
*/
public class MethodCallTightener {
/**
* Updates polymorphic method calls to tighter bindings based on the type of
* the qualifier.
*/
public class MethodCallTighteningVisitor extends JModVisitor {
@Override
public void endVisit(JMethodCall x, Context ctx) {
// The method call is already known statically
if (x.isVolatile() || !x.canBePolymorphic()) {
return;
}
JType instanceType = x.getInstance().getType().getUnderlyingType();
if (!(instanceType instanceof JClassType)) {
// Cannot tighten.
return;
}
JMethod method = x.getTarget();
if (instanceType == method.getEnclosingType()) {
// Cannot tighten.
return;
}
JMethod foundMethod = program.typeOracle.getInstanceMethodBySignature(
(JClassType) instanceType, method.getSignature());
if (foundMethod == null || !foundMethod.canBePolymorphic()) {
// The declared instance type is abstract and doesn't have the method.
return;
}
if (foundMethod == method) {
// The instance type doesn't override the method.
return;
}
if (!foundMethod.getOverriddenMethods().contains(method)) {
// The found method has the same signature as the target method of the call being tightened
// but does NOT override it. this situation occurs for example when the target method is
// package private and the found method is a method with the same name and signature as the
// target method in a subclass declared in a different package).
return;
}
/*
* Replace the call to the original method with a call to the same method
* on the tighter type.
*/
JMethodCall call = new JMethodCall(x.getSourceInfo(), x.getInstance(), foundMethod);
call.addArgs(x.getArgs());
ctx.replaceMe(call);
}
@Override
public void endVisit(JNewInstance x, Context ctx) {
// Do not tighten new operations.
}
@Override
public boolean visit(JRunAsync x, Context ctx) {
x.traverseOnSuccess(this);
return super.visit(x, ctx);
}
}
public static final String NAME = MethodCallTightener.class.getSimpleName();
public static OptimizerStats exec(JProgram program) {
Event optimizeEvent = SpeedTracerLogger.start(CompilerEventType.OPTIMIZE, "optimizer", NAME);
OptimizerStats stats = new MethodCallTightener(program).execImpl();
optimizeEvent.end("didChange", "" + stats.didChange());
return stats;
}
private final JProgram program;
private MethodCallTightener(JProgram program) {
this.program = program;
}
private OptimizerStats execImpl() {
MethodCallTighteningVisitor tightener = new MethodCallTighteningVisitor();
tightener.accept(program);
return new OptimizerStats(NAME).recordModified(tightener.getNumMods());
}
}