RFR: 8371789: C2: More explicit dump results for TypePtr

[Quan Anh Mai]

On Thu, 13 Nov 2025 12:45:23 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> Hi,
>> 
>> This patch tries to clear up the dumped information of `TypePtr` and its subclasses. It makes it immediately clear the states of the `Type` object without us having to look into the implementation of `dump2`, for example, to know that the absence of `:NotNull` implies that it is a `BotPTR`.
>> 
>> Please take a look and kindly review, thanks a lot.
>
> That looks like a nice readability improvement! Can you show some before vs. after output to summarize your changes?

@chhagedorn Yes, for example:

A byte array:

    Before:
    byte[int:>=0] (java/lang/Cloneable,java/io/Serializable):exact *
    After:
    aryptr:byte[int:>=0] (java/lang/Cloneable,java/io/Serializable):BotPTR:exact,iid=bot

A `j.l.Object`:

    Before:
    narrowoop: java/lang/Object *
    After:
    narrowoop: instptr:java/lang/Object:BotPTR+0,iid=bot

A pointer to the klass of `Object[]`:

    Before:
    precise [java/lang/Object: 0x00007011e800b840 * (java/lang/Cloneable,java/io/Serializable): :Constant:exact *
    After:
    aryklassptr:[instklassptr:java/lang/Object:NotNull+0 (java/lang/Cloneable,java/io/Serializable):Constant+0

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PR Comment: https://git.openjdk.org/jdk/pull/28292#issuecomment-3528364010