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[GR-59590] Reduce vtable slots in application layer. #10544

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[GR-59590] Reduce vtable slots in application layer. #10544

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26 changes: 13 additions & 13 deletions substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/meta/VTableBuilder.java
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Original file line number Diff line number Diff line change
Expand Up @@ -70,28 +70,28 @@ private static class OpenTypeWorldHubLayoutUtils {
private final boolean closedTypeWorld;
private final boolean registerTrackedTypes;
private final boolean registerAllTypes;
private final boolean filterVTableMethods;

OpenTypeWorldHubLayoutUtils(HostedUniverse hUniverse) {
closedTypeWorld = SubstrateOptions.useClosedTypeWorld();

/*
* We only filter vtable methods when we are building a non-layered image under the
* closed type world assumption. For layered builds, we must keep all vtable methods to
* ensure consistency across layers.
*
* With the closed type world assumption we can filter out methods that we know will be
* simplified to direct calls (i.e., when at most a single implementation exists for the
* given target). See generateDispatchTable for the use of this filter.
*/
filterVTableMethods = closedTypeWorld && !ImageLayerBuildingSupport.buildingImageLayer();

registerTrackedTypes = hUniverse.hostVM().enableTrackAcrossLayers();
registerAllTypes = ImageLayerBuildingSupport.buildingApplicationLayer();
assert !(registerTrackedTypes && registerAllTypes) : "We expect these flags to be mutually exclusive";
assert (registerTrackedTypes || registerAllTypes) == ImageLayerBuildingSupport.buildingImageLayer() : "Type information must be registered during layered image builds";
}

/**
* We are allowed to filter vtables as long as we know the type layout does not need to
* match the layout of another layer.
*
* When filtering is allowed, we can filter out methods that we know will be simplified to
* direct calls (i.e., when at most a single implementation exists for the given target).
* See generateDispatchTable for the use of this filter.
*/
private boolean filterVTableMethods(HostedType type) {
return closedTypeWorld && !type.getWrapped().isInBaseLayer();
}

private boolean shouldIncludeType(HostedType type) {
if (closedTypeWorld) {
if (type.getWrapped().isInBaseLayer()) {
Expand Down Expand Up @@ -183,7 +183,7 @@ private List<HostedMethod> generateITable(HostedType type) {

private List<HostedMethod> generateDispatchTable(HostedType type, int startingIndex) {
Predicate<HostedMethod> includeMethod;
if (openHubUtils.filterVTableMethods) {
if (openHubUtils.filterVTableMethods(type)) {
// include only methods which will be indirect calls
includeMethod = m -> {
assert !m.isConstructor() : Assertions.errorMessage("Constructors should never be in dispatch tables", m);
Expand Down