RFR: 8357568: IGV: Show NULL and numbers up to 4 characters in "Condense graph" filter [v2]

[Christian Hagedorn]

On Fri, 23 May 2025 07:30:18 GMT, Marc Chevalier <mchevalier at openjdk.org> wrote:

>> Christian Hagedorn has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Increase number of parameters as suggested by Manuel
>
> I like it.

Pushed an update to use "Null", an update to count the number of chars written as suggested by @marc-chevalier, and also added a missing case when we just have

object = null

somewhere and having narrow oops. We currently miss this because we would have `t->base() == NarrowOop`.

> src/hotspot/share/opto/idealGraphPrinter.cpp line 657:
> 
>> 655: 
>> 656:         // Only use up to 4 chars and fall back to a generic "L" to keep it short.
>> 657:         if (value >= -999 && value <= 9999) {
> 
> Just for the sake of saying something, can we somewhat factor this test? And ideally, it could be marginally nicer, if I want to see 6 chars, to just replace a 4 into a 6 and it'd work magically. But I don't really see a way beside length(to_string(value)) <= max_length, and it's not really efficient so... If you have a brilliant idea, good. Otherwise, feel free to ignore: changing it as it is now is easy too.

Good point! I think we can directly check how many chars are written with `snprintf_checked` and use that as an indicator. I pushed an update.

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PR Comment: https://git.openjdk.org/jdk/pull/25393#issuecomment-2903777492
PR Review Comment: https://git.openjdk.org/jdk/pull/25393#discussion_r2104157456