RFR: 8310849: Pattern matching for instanceof and arrayType cleanup in j.l.invoke and j.l.reflect [v2]

[Chen Liang]

On Mon, 26 Jun 2023 12:57:34 GMT, Glavo <duke at openjdk.org> wrote:

>> Chen Liang has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:
>> 
>>  - Merge branch 'master' into cleanup/invoke-instanceof
>>  - 8310849: Pattern matching for instanceof and arrayType cleanup in j.l.invoke and j.l.reflect
>
> src/java.base/share/classes/sun/invoke/util/ValueConversions.java line 239:
> 
>> 237:             return ZERO_INT;
>> 238:         }
>> 239:         if (x instanceof Number n) {
> 
> Number res = switch (x) {
>     case Number n -> n;
>     case Boolean b -> b ? ONE_INT : ZERO_INT;
>     case Character c -> (int) c;
>     // this will fail with the required ClassCastException:
>     default -> (Number) x;
> };

Unfortunately, this is used by MethodHandleImpl, so can't use indy switches.

> src/java.base/share/classes/sun/invoke/util/ValueConversions.java line 262:
> 
>> 260:      */
>> 261:     public static int widenSubword(Object x) {
>> 262:         if (x instanceof Integer i)
> 
> return switch (x) {
>     case Integer i -> i;
>     case Boolean b -> fromBoolean(b);
>     case Character c -> c;
>     case Short s -> s;
>     case Byte b -> b;
>     // Fail with a ClassCastException.
>     case null, default -> (int) x;
> };

Also used by MethodHandles.insertArgumentPrimitive, likely not safe.

> src/java.base/share/classes/sun/invoke/util/Wrapper.java line 583:
> 
>> 581: 
>> 582:     private static Number numberValue(Object x) {
>> 583:         if (x instanceof Number n)     return n;
> 
> return switch (x) {
>     case Number n -> n;
>     case Character c -> (int) c;
>     case Boolean b -> b ? 1 : 0;
>     // Remaining allowed case of void: Must be a null reference.
>     case null, default -> (Number) x;
> };

This is used by Wrapper.convert and MethodHandles.insertArgumentPrimitive, which I don't think is a safe candidate either.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/14642#discussion_r1242192173
PR Review Comment: https://git.openjdk.org/jdk/pull/14642#discussion_r1242196620
PR Review Comment: https://git.openjdk.org/jdk/pull/14642#discussion_r1242195548