Integrated: 8339694: ciTypeFlow does not correctly handle unresolved constant dynamic of array type

[Tobias Hartmann]

On Fri, 11 Oct 2024 13:44:46 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

> After [JDK-8280473](https://bugs.openjdk.org/browse/JDK-8280473), the CI will represent an unresolved constant dynamic as unloaded `ciConstant` of a `java/lang/Object` `ciInstanceKlass`:
> 
> https://github.com/openjdk/jdk/blob/6133866150cf6131ab578f1537f84c239703fa67/src/hotspot/share/ci/ciEnv.cpp#L721-L723
> 
> Now with a constant dynamic of array type, we hit an assert in type flow analysis on `*astore` because the type is not a primitive array type:
> 
> https://github.com/openjdk/jdk/blob/6133866150cf6131ab578f1537f84c239703fa67/src/hotspot/share/ci/ciTypeFlow.cpp#L967-L971
> 
> ->
> https://github.com/openjdk/jdk/blob/6133866150cf6131ab578f1537f84c239703fa67/src/hotspot/share/ci/ciTypeFlow.hpp#L343-L346
> 
> The same problem exists with object array types. New `TestUnresolvedConstantDynamic` triggers both.
> 
> Similar to `unloaded_ciinstance` used by [JDK-8280473](https://bugs.openjdk.org/browse/JDK-8280473) (see [here](https://github.com/openjdk/jdk/commit/88fc3bfdff7f89a02fcfb16909df144e6173c658#diff-7c032de54e85754d39e080fd24d49b7469543b163f54229eb0631c6b1bf26450R784)), we could now add an unloaded `ciObjArray` and `ciTypeArray` to represent an unresolved dynamic constant of array type. We would then add a trap when parsing the array access. However, this requires rather invasive changes for this edge case and it wouldn't make much sense because even though type flow analysis would continue, we would add a trap when parsing `_ldc` anyway if the constant is not loaded: 
> https://github.com/openjdk/jdk/blob/037f11b864734734dd7fbce029b2e8b4bc17f3ab/src/hotspot/share/opto/parse2.cpp#L1962-L1979
> 
> I propose to do the same in type flow analysis, i.e., trap early in `_ldc` when the constant is not loaded.
> 
> Thanks,
> Tobias

This pull request has now been integrated.

Changeset: c51a086c
Author:    Tobias Hartmann <thartmann at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/c51a086ce32dd4e97aa83dfba3bcf9b0636193cc
Stats:     135 lines in 5 files changed: 111 ins; 18 del; 6 mod

8339694: ciTypeFlow does not correctly handle unresolved constant dynamic of array type

Reviewed-by: kvn, vlivanov

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PR: https://git.openjdk.org/jdk/pull/21470