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8332522: SwitchBootstraps::mappedEnumLookup constructs unused array

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Reviewed-by: liach, redestad
This commit is contained in:
Jan Lahoda 2024-08-06 09:07:44 +00:00
parent f92c60e1a9
commit 958786b28f
2 changed files with 177 additions and 38 deletions
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110
src/java.base/share/classes/java/lang/runtime/SwitchBootstraps.java
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@ -56,6 +56,7 @@ import jdk.internal.vm.annotation.Stable;
import static java.lang.invoke.MethodHandles.Lookup.ClassOption.NESTMATE;
import static java.lang.invoke.MethodHandles.Lookup.ClassOption.STRONG;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import static java.util.Objects.requireNonNull;
@ -95,19 +96,13 @@ public class SwitchBootstraps {
private static final ClassDesc CD_Objects = ReferenceClassDescImpl.ofValidated("Ljava/util/Objects;");
private static class StaticHolders {
private static final MethodHandle NULL_CHECK;
private static final MethodHandle IS_ZERO;
private static final MethodHandle MAPPED_ENUM_LOOKUP;
private static final MethodHandle MAPPED_ENUM_SWITCH;
static {
try {
NULL_CHECK = LOOKUP.findStatic(Objects.class, "isNull",
MethodType.methodType(boolean.class, Object.class));
IS_ZERO = LOOKUP.findStatic(SwitchBootstraps.class, "isZero",
MethodType.methodType(boolean.class, int.class));
MAPPED_ENUM_LOOKUP = LOOKUP.findStatic(SwitchBootstraps.class, "mappedEnumLookup",
MethodType.methodType(int.class, Enum.class, MethodHandles.Lookup.class,
Class.class, EnumDesc[].class, EnumMap.class));
MAPPED_ENUM_SWITCH = LOOKUP.findStatic(SwitchBootstraps.class, "mappedEnumSwitch",
MethodType.methodType(int.class, Enum.class, int.class, MethodHandles.Lookup.class,
Class.class, EnumDesc[].class, MappedEnumCache.class));
}
catch (ReflectiveOperationException e) {
throw new ExceptionInInitializerError(e);
@ -211,10 +206,6 @@ public class SwitchBootstraps {
}
}
private static boolean isZero(int value) {
return value == 0;
}
/**
* Bootstrap method for linking an {@code invokedynamic} call site that
* implements a {@code switch} on a target of an enum type. The static
@ -286,23 +277,27 @@ public class SwitchBootstraps {
labels = labels.clone();
Class<?> enumClass = invocationType.parameterType(0);
labels = Stream.of(labels).map(l -> convertEnumConstants(lookup, enumClass, l)).toArray();
boolean constantsOnly = true;
int len = labels.length;
for (int i = 0; i < len; i++) {
Object convertedLabel =
convertEnumConstants(lookup, enumClass, labels[i]);
labels[i] = convertedLabel;
if (constantsOnly)
constantsOnly = convertedLabel instanceof EnumDesc;
}
MethodHandle target;
boolean constantsOnly = Stream.of(labels).allMatch(l -> enumClass.isAssignableFrom(EnumDesc.class));
if (labels.length > 0 && constantsOnly) {
//If all labels are enum constants, construct an optimized handle for repeat index 0:
//if (selector == null) return -1
//else if (idx == 0) return mappingArray[selector.ordinal()]; //mapping array created lazily
//else return "typeSwitch(labels)"
MethodHandle body =
MethodHandles.guardWithTest(MethodHandles.dropArguments(StaticHolders.NULL_CHECK, 0, int.class),
MethodHandles.dropArguments(MethodHandles.constant(int.class, -1), 0, int.class, Object.class),
MethodHandles.guardWithTest(MethodHandles.dropArguments(StaticHolders.IS_ZERO, 1, Object.class),
generateTypeSwitch(lookup, invocationType.parameterType(0), labels),
MethodHandles.insertArguments(StaticHolders.MAPPED_ENUM_LOOKUP, 1, lookup, enumClass, labels, new EnumMap())));
target = MethodHandles.permuteArguments(body, MethodType.methodType(int.class, Object.class, int.class), 1, 0);
EnumDesc<?>[] enumDescLabels =
Arrays.copyOf(labels, labels.length, EnumDesc[].class);
target = MethodHandles.insertArguments(StaticHolders.MAPPED_ENUM_SWITCH, 2, lookup, enumClass, enumDescLabels, new MappedEnumCache());
} else {
target = generateTypeSwitch(lookup, invocationType.parameterType(0), labels);
}
@ -331,26 +326,63 @@ public class SwitchBootstraps {
}
}
private static <T extends Enum<T>> int mappedEnumLookup(T value, MethodHandles.Lookup lookup, Class<T> enumClass, EnumDesc<?>[] labels, EnumMap enumMap) {
if (enumMap.map == null) {
T[] constants = SharedSecrets.getJavaLangAccess().getEnumConstantsShared(enumClass);
int[] map = new int[constants.length];
int ordinal = 0;
private static <T extends Enum<T>> int mappedEnumSwitch(T value, int restartIndex, MethodHandles.Lookup lookup, Class<T> enumClass, EnumDesc<?>[] labels, MappedEnumCache enumCache) throws Throwable {
if (value == null) {
return -1;
}
for (T constant : constants) {
map[ordinal] = labels.length;
if (restartIndex != 0) {
MethodHandle generatedSwitch = enumCache.generatedSwitch;
if (generatedSwitch == null) {
synchronized (enumCache) {
generatedSwitch = enumCache.generatedSwitch;
for (int i = 0; i < labels.length; i++) {
if (Objects.equals(labels[i].constantName(), constant.name())) {
map[ordinal] = i;
break;
if (generatedSwitch == null) {
generatedSwitch =
generateTypeSwitch(lookup, enumClass, labels)
.asType(MethodType.methodType(int.class,
Enum.class,
int.class));
enumCache.generatedSwitch = generatedSwitch;
}
}
}
ordinal++;
return (int) generatedSwitch.invokeExact(value, restartIndex);
}
int[] constantsMap = enumCache.constantsMap;
if (constantsMap == null) {
synchronized (enumCache) {
constantsMap = enumCache.constantsMap;
if (constantsMap == null) {
T[] constants = SharedSecrets.getJavaLangAccess()
.getEnumConstantsShared(enumClass);
constantsMap = new int[constants.length];
int ordinal = 0;
for (T constant : constants) {
constantsMap[ordinal] = labels.length;
for (int i = 0; i < labels.length; i++) {
if (Objects.equals(labels[i].constantName(),
constant.name())) {
constantsMap[ordinal] = i;
break;
}
}
ordinal++;
}
enumCache.constantsMap = constantsMap;
}
}
}
return enumMap.map[value.ordinal()];
return constantsMap[value.ordinal()];
}
private static final class ResolvedEnumLabels implements BiPredicate<Integer, Object> {
@ -395,9 +427,11 @@ public class SwitchBootstraps {
}
}
private static final class EnumMap {
private static final class MappedEnumCache {
@Stable
public int[] map;
public int[] constantsMap;
@Stable
public MethodHandle generatedSwitch;
}
/*