/**
* Creates a JMultiExpression from a set of JExpressionStatements, optionally terminated by a
* JReturnStatement. If the method doesn't match this pattern, it returns <code>null</code>.
*
* <p>If a method has a non-void return statement and can be represented as a multi-expression,
* the output of the multi-expression will be the return expression of the method. If the method
* is void, the output of the multi-expression should be considered undefined.
*/
private JMultiExpression createMultiExpressionFromBody(
JMethodBody body, boolean ignoringReturnValue) {
JMultiExpression multi = new JMultiExpression(body.getSourceInfo());
CloneCalleeExpressionVisitor cloner = new CloneCalleeExpressionVisitor();
for (JStatement stmt : body.getStatements()) {
if (stmt instanceof JExpressionStatement) {
JExpressionStatement exprStmt = (JExpressionStatement) stmt;
JExpression expr = exprStmt.getExpr();
JExpression clone = cloner.cloneExpression(expr);
multi.addExpressions(clone);
} else if (stmt instanceof JReturnStatement) {
JReturnStatement returnStatement = (JReturnStatement) stmt;
JExpression expr = returnStatement.getExpr();
if (expr != null) {
if (!ignoringReturnValue || expr.hasSideEffects()) {
JExpression clone = cloner.cloneExpression(expr);
clone = maybeCast(clone, body.getMethod().getType());
multi.addExpressions(clone);
}
}
// We hit an unconditional return; no need to evaluate anything else.
break;
} else {
// Any other kind of statement won't be inlinable.
return null;
}
}
return multi;
}
/**
* Transform a call to a pruned instance method (or static impl) into a call to the null method,
* which will be used to replace <code>x</code>.
*/
public static JMethodCall transformToNullMethodCall(JMethodCall x, JProgram program) {
JExpression instance = x.getInstance();
List<JExpression> args = x.getArgs();
if (program.isStaticImpl(x.getTarget())) {
instance = args.get(0);
args = args.subList(1, args.size());
} else {
/*
* We assert that method must be non-static, otherwise it would have been
* rescued.
*/
// assert !x.getTarget().isStatic();
/*
* HACK HACK HACK: ControlFlowAnalyzer has special hacks for dealing with
* ClassLiterals, which causes the body of ClassLiteralHolder's clinit to
* never be rescured. This in turn causes invalid references to static
* methods, which violates otherwise good assumptions about compiler
* operation.
*
* TODO: Remove this when ControlFlowAnalyzer doesn't special-case
* CLH.clinit().
*/
if (x.getTarget().isStatic() && instance == null) {
instance = program.getLiteralNull();
}
}
assert (instance != null);
if (!instance.hasSideEffects()) {
instance = program.getLiteralNull();
}
JMethodCall newCall =
new JMethodCall(
x.getSourceInfo(),
instance,
program.getNullMethod(),
primitiveTypeOrNullTypeOrArray(program, x.getType()));
// Retain the original arguments, they will be evaluated for side effects.
for (JExpression arg : args) {
if (arg.hasSideEffects()) {
newCall.addArg(arg);
}
}
return newCall;
}
@Override
public boolean hasSideEffects() {
for (JExpression expression : expressions) {
if (expression.hasSideEffects()) {
return true;
}
}
return false;
}
/**
* Creates a multi expression from a list of expressions, removing expressions that do not have
* side effects if possible.
*/
public static JExpression createOptimizedMultiExpression(
boolean ignoringResult, List<JExpression> expressions) {
int numberOfExpressions = expressions.size();
JExpression result = expressions.get(numberOfExpressions - 1);
numberOfExpressions = expressions.size();
if (numberOfExpressions == 0) {
return new JMultiExpression(SourceOrigin.UNKNOWN);
}
expressions =
Lists.newArrayList(
Collections2.filter(
expressions.subList(0, numberOfExpressions - 1),
Predicates.and(
Predicates.notNull(),
new Predicate<JExpression>() {
@Override
public boolean apply(JExpression expression) {
return expression.hasSideEffects();
}
})));
if (result != null && (!ignoringResult || result.hasSideEffects())) {
expressions.add(result);
}
if (expressions.size() == 1) {
// Do not create a multi expression if it consists only of the result.
return expressions.iterator().next();
}
SourceInfo info =
expressions.size() > 0 ? expressions.get(0).getSourceInfo() : SourceOrigin.UNKNOWN;
return new JMultiExpression(info, expressions);
}
/**
* Transform a reference to a pruned instance field into a reference to the null field, which will
* be used to replace <code>x</code>.
*/
public static JFieldRef transformToNullFieldRef(JFieldRef x, JProgram program) {
JExpression instance = x.getInstance();
/*
* We assert that field must be non-static if it's an rvalue, otherwise it
* would have been rescued.
*/
// assert !x.getField().isStatic();
/*
* HACK HACK HACK: ControlFlowAnalyzer has special hacks for dealing with
* ClassLiterals, which causes the body of ClassLiteralHolder's clinit to
* never be rescured. This in turn causes invalid references to static
* methods, which violates otherwise good assumptions about compiler
* operation.
*
* TODO: Remove this when ControlFlowAnalyzer doesn't special-case
* CLH.clinit().
*/
if (x.getField().isStatic() && instance == null) {
instance = program.getLiteralNull();
}
assert instance != null;
if (!instance.hasSideEffects()) {
instance = program.getLiteralNull();
}
JFieldRef fieldRef =
new JFieldRef(
x.getSourceInfo(),
instance,
program.getNullField(),
x.getEnclosingType(),
primitiveTypeOrNullTypeOrArray(program, x.getType()));
return fieldRef;
}
// Arguments for pruned parameters will be pushed right into a multiexpression that will be
// evaluated with the next arg, e.g. m(arg1, (prunnedArg2, prunnedArg3, arg4)).
private void maybeReplaceForPrunedParameters(JMethodCall x, Context ctx) {
if (!priorParametersByMethod.containsKey(x.getTarget())) {
// No parameter was pruned.
return;
}
JMethodCall replacementCall = x.cloneWithoutParameters();
assert !x.getTarget().canBePolymorphic();
List<JParameter> originalParams = priorParametersByMethod.get(x.getTarget());
// The method and the call agree in the number of parameters.
assert originalParams.size() == x.getArgs().size();
// Traverse the call arguments left to right.
SourceInfo sourceInfo = x.getSourceInfo();
JMultiExpression unevaluatedArgumentsForPrunedParameters = new JMultiExpression(sourceInfo);
List<JExpression> args = x.getArgs();
for (int currentArgumentIndex = 0;
currentArgumentIndex < args.size();
++currentArgumentIndex) {
JExpression arg = args.get(currentArgumentIndex);
// If the parameter was not pruned .
if (referencedNonTypes.contains(originalParams.get(currentArgumentIndex))) {
// Add the current argument to the list of unevaluated arguments and pass the multi
// expression to the call.
unevaluatedArgumentsForPrunedParameters.addExpressions(arg);
replacementCall.addArg(unevaluatedArgumentsForPrunedParameters);
// Reset the accumulating multi expression.
unevaluatedArgumentsForPrunedParameters = new JMultiExpression(sourceInfo);
} else if (arg.hasSideEffects()) {
// If the argument was pruned and has sideffects accumulate it; otherwise discard.
unevaluatedArgumentsForPrunedParameters.addExpressions(arg);
}
}
if (unevaluatedArgumentsForPrunedParameters.isEmpty()) {
// We are done, all (side effectful) parameters have been evaluated.
ctx.replaceMe(replacementCall);
return;
}
// If the last few parameters where pruned, we need to evaluate the (side effectful) arguments
// for those parameters.
if (replacementCall.getArgs().isEmpty()) {
// All parameters have been pruned, replace by (prunedArg1, ..., prunedArgn, m()).
unevaluatedArgumentsForPrunedParameters.addExpressions(replacementCall);
ctx.replaceMe(unevaluatedArgumentsForPrunedParameters);
return;
}
// Some parameters have been pruned from the end, replace by
// m(arg1,..., (lastArg = lastUnprunedArg, remainingArgs, lastArg))
JExpression lastArg = Iterables.getLast(replacementCall.getArgs());
JLocal tempVar =
createTempLocal(
sourceInfo,
Iterables.getLast(Iterables.filter(originalParams, Predicates.in(referencedNonTypes)))
.getType());
unevaluatedArgumentsForPrunedParameters.addExpressions(
0,
JProgram.createAssignment(
lastArg.getSourceInfo(), new JLocalRef(sourceInfo, tempVar), lastArg));
unevaluatedArgumentsForPrunedParameters.addExpressions(new JLocalRef(sourceInfo, tempVar));
replacementCall.setArg(
replacementCall.getArgs().size() - 1, unevaluatedArgumentsForPrunedParameters);
ctx.replaceMe(replacementCall);
}
