/**
* Similar to {@link #deverbosifyInputsInPlace(com.oracle.graal.nodes.ValueNode)}, except that not
* the parent but a fresh clone is updated upon any of its children changing.
*
* @return the original parent if no updated took place, a copy-on-write version of it otherwise.
*/
private MethodCallTargetNode deverbosifyInputsCopyOnWrite(MethodCallTargetNode parent) {
final CallTargetNode.InvokeKind ik = parent.invokeKind();
final boolean shouldTryDevirt =
(ik == CallTargetNode.InvokeKind.Interface || ik == CallTargetNode.InvokeKind.Virtual);
boolean shouldDowncastReceiver = shouldTryDevirt;
MethodCallTargetNode changed = null;
for (ValueNode i : FlowUtil.distinctValueAndConditionInputs(parent)) {
ValueNode j = (ValueNode) reasoner.deverbosify(i);
if (shouldDowncastReceiver) {
shouldDowncastReceiver = false;
j = reasoner.downcast(j);
}
if (i != j) {
assert j != parent;
if (changed == null) {
changed = (MethodCallTargetNode) parent.copyWithInputs();
reasoner.added.add(changed);
// copyWithInputs() implies graph.unique(changed)
assert changed.isAlive();
assert FlowUtil.lacksUsages(changed);
}
FlowUtil.replaceInPlace(changed, i, j);
}
}
if (changed == null) {
return parent;
}
FlowUtil.inferStampAndCheck(changed);
/*
* No need to rememberSubstitution() because not called from deverbosify(). In detail, it's
* only deverbosify() that skips visited nodes (thus we'd better have recorded any
* substitutions we want for them). Not this case.
*/
return changed;
}
/**
* Reduce input nodes based on the state at the program point for the argument (ie, based on
* "valid facts" only, without relying on any floating-guard-assumption).
*
* <p>For each (direct or indirect) child, a copy-on-write version is made in case any of its
* children changed, with the copy accommodating the updated children. If the parent was shared,
* copy-on-write prevents the updates from becoming visible to anyone but the invoker of this
* method.
*
* <p><b> Please note the parent node is mutated upon any descendant changing. No copy-on-write is
* performed for the parent node itself. </b>
*
* <p>In more detail, for each direct {@link com.oracle.graal.nodes.ValueNode} input of the node
* at hand,
*
* <ol>
* <li>Obtain a lazy-copied version (via spanning tree) of the DAG rooted at the input-usage in
* question. Lazy-copying is done by walking a spanning tree of the original DAG, stopping
* at non-FloatingNodes but transitively walking FloatingNodes and their inputs. Upon
* arriving at a (floating) node N, the state's facts are checked to determine whether a
* constant C can be used instead in the resulting lazy-copied DAG. A NodeBitMap is used to
* realize the spanning tree.
* <li>Provided one or more N-to-C node replacements took place, the resulting lazy-copied DAG
* has a parent different from the original (ie different object identity) which indicates
* the (copied, updated) DAG should replace the original via replaceFirstInput(), and
* inferStamp() should be invoked to reflect the updated inputs.
* </ol>
*
* @return whether any reduction was performed on the inputs of the arguments.
*/
public boolean deverbosifyInputsInPlace(ValueNode parent) {
boolean changed = false;
for (ValueNode i : FlowUtil.distinctValueAndConditionInputs(parent)) {
assert !(i instanceof GuardNode) : "This phase not intended to run during MidTier";
ValueNode j = (ValueNode) reasoner.deverbosify(i);
if (i != j) {
changed = true;
FlowUtil.replaceInPlace(parent, i, j);
}
}
if (changed) {
FlowUtil.inferStampAndCheck(parent);
}
return changed;
}
/**
* For one or more `invoke` arguments, flow-sensitive information may suggest their narrowing or
* simplification. In those cases, a new {@link com.oracle.graal.nodes.java.MethodCallTargetNode
* MethodCallTargetNode} is prepared just for this callsite, consuming reduced arguments.
*
* <p>Specializing the {@link com.oracle.graal.nodes.java.MethodCallTargetNode
* MethodCallTargetNode} as described above may enable two optimizations:
*
* <ul>
* <li>devirtualization of an {@link com.oracle.graal.nodes.CallTargetNode.InvokeKind#Interface}
* or {@link com.oracle.graal.nodes.CallTargetNode.InvokeKind#Virtual} callsite
* (devirtualization made possible after narrowing the type of the receiver)
* <li>(future work) actual-argument-aware inlining, ie, to specialize callees on the types of
* arguments other than the receiver (examples: multi-methods, the inlining problem, lambdas
* as arguments).
* </ul>
*
* <p>Precondition: inputs haven't been deverbosified yet.
*/
private void visitInvoke(Invoke invoke) {
if (invoke.asNode().stamp() instanceof IllegalStamp) {
return; // just to be safe
}
boolean isMethodCallTarget = invoke.callTarget() instanceof MethodCallTargetNode;
if (!isMethodCallTarget) {
return;
}
FlowUtil.replaceInPlace(
invoke.asNode(),
invoke.callTarget(),
deverbosifyInputsCopyOnWrite((MethodCallTargetNode) invoke.callTarget()));
MethodCallTargetNode callTarget = (MethodCallTargetNode) invoke.callTarget();
if (callTarget.invokeKind() != CallTargetNode.InvokeKind.Interface
&& callTarget.invokeKind() != CallTargetNode.InvokeKind.Virtual) {
return;
}
ValueNode receiver = callTarget.receiver();
if (receiver == null) {
return;
}
if (!FlowUtil.hasLegalObjectStamp(receiver)) {
return;
}
Witness w = state.typeInfo(receiver);
ResolvedJavaType type;
ResolvedJavaType stampType = StampTool.typeOrNull(receiver);
if (w == null || w.cluelessAboutType()) {
// can't improve on stamp but wil try to devirtualize anyway
type = stampType;
} else {
type = FlowUtil.tighten(w.type(), stampType);
}
if (type == null) {
return;
}
ResolvedJavaMethod method =
type.resolveMethod(callTarget.targetMethod(), invoke.getContextType());
if (method == null) {
return;
}
if (method.canBeStaticallyBound() || Modifier.isFinal(type.getModifiers())) {
metricMethodResolved.increment();
callTarget.setInvokeKind(CallTargetNode.InvokeKind.Special);
callTarget.setTargetMethod(method);
}
}