RFR: 8263448: CTW: fatal error: meet not symmetric

[Roland Westrelin]

On Wed, 31 Mar 2021 23:31:05 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> In bug's case instance_id should be changed to InstanceBot only if it is real id and not InstanceTop or InstanceBot (similar to Constant in type lattice). Otherwise we incorrectly change InstanceTop to InstanceBot.  In short, we should follow PTR transformation in this code:
>       if (ptr == Constant) {
>          ptr = NotNull;
>       }
> -     instance_id = InstanceBot;
> +     if (instance_id > 0) {
> +       instance_id = InstanceBot;
> +     }
> I noticed that `TypeInstPtr::xmeet_helper()` has the same code as `TypeAryPtr::xmeet_helper()` for case when `InstPtr` meets `AryPtr`. So instead of fixing two places I decided to call TypeAryPtr::xmeet_helper() from `TypeInstPtr::xmeet_helper()` for this case. We do similar thing in `TypeOopPtr::xmeet()`:
> https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/type.cpp#L3283
> 
> Fixed code style in touched code.
> 
> Tested failing test from bug report, hs-tier1-4, hs-comp.

Looks good to me.

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Marked as reviewed by roland (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/3298