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8213478: Reduce rebinds when applying repeated filters and conversions

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Reviewed-by: vlivanov, jrose
This commit is contained in:
Claes Redestad 2018-11-11 21:24:46 +01:00
parent 2df435e191
commit eda5f09014
3 changed files with 198 additions and 101 deletions
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51
src/java.base/share/classes/java/lang/invoke/MethodHandles.java
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@ -3864,18 +3864,63 @@ assertEquals("XY", (String) f2.invokeExact("x", "y")); // XY
*/
public static
MethodHandle filterArguments(MethodHandle target, int pos, MethodHandle... filters) {
// In method types arguments start at index 0, while the LF
// editor have the MH receiver at position 0 - adjust appropriately.
final int MH_RECEIVER_OFFSET = 1;
filterArgumentsCheckArity(target, pos, filters);
MethodHandle adapter = target;
// keep track of currently matched filters, as to optimize repeated filters
int index = 0;
int[] positions = new int[filters.length];
MethodHandle filter = null;
// process filters in reverse order so that the invocation of
// the resulting adapter will invoke the filters in left-to-right order
for (int i = filters.length - 1; i >= 0; --i) {
MethodHandle filter = filters[i];
if (filter == null) continue; // ignore null elements of filters
adapter = filterArgument(adapter, pos + i, filter);
MethodHandle newFilter = filters[i];
if (newFilter == null) continue; // ignore null elements of filters
// flush changes on update
if (filter != newFilter) {
if (filter != null) {
if (index > 1) {
adapter = filterRepeatedArgument(adapter, filter, Arrays.copyOf(positions, index));
} else {
adapter = filterArgument(adapter, positions[0] - 1, filter);
}
}
filter = newFilter;
index = 0;
}
filterArgumentChecks(target, pos + i, newFilter);
positions[index++] = pos + i + MH_RECEIVER_OFFSET;
}
if (index > 1) {
adapter = filterRepeatedArgument(adapter, filter, Arrays.copyOf(positions, index));
} else if (index == 1) {
adapter = filterArgument(adapter, positions[0] - 1, filter);
}
return adapter;
}
private static MethodHandle filterRepeatedArgument(MethodHandle adapter, MethodHandle filter, int[] positions) {
MethodType targetType = adapter.type();
MethodType filterType = filter.type();
BoundMethodHandle result = adapter.rebind();
Class<?> newParamType = filterType.parameterType(0);
Class<?>[] ptypes = targetType.ptypes().clone();
for (int pos : positions) {
ptypes[pos - 1] = newParamType;
}
MethodType newType = MethodType.makeImpl(targetType.rtype(), ptypes, true);
LambdaForm lform = result.editor().filterRepeatedArgumentForm(BasicType.basicType(newParamType), positions);
return result.copyWithExtendL(newType, lform, filter);
}
/*non-public*/ static
MethodHandle filterArgument(MethodHandle target, int pos, MethodHandle filter) {
filterArgumentChecks(target, pos, filter);