[lworld+vector] RFR: 8309777: [lworld+vector] Fix re-materialize crash for vector objects with un-vectorized multi-fields during deoptimization

[Xiaohong Gong]

On Tue, 20 Jun 2023 06:23:58 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

> Some vector API jtreg tests crash when running on hardwares that do
>  not support the relative vector species.
> 
> Here is the log:
> 
> 
>   A fatal error has been detected by the Java Runtime Environment:
> 
>   Internal Error (valhalla/src/hotspot/share/prims/vectorSupport.cpp:317), pid=2529357, tid=2529377
>   assert(loc_type == Location::oop || loc_type == Location::narrowoop) failed: expected 'oop'(2) or 'narrowoop'(9) types location but got: 3
> 
>   JRE version: OpenJDK Runtime Environment (21.0) (fastdebug build 21-internal-git-62ba7fc27)
>   Java VM: OpenJDK 64-Bit Server VM (fastdebug 21-internal-git-62ba7fc27, mixed mode, sharing, compressed oops, compressed class ptrs, g1 gc, linux-aarch64)
>   Problematic frame:
>   V [[libjvm.so](http://libjvm.so/)+0x1aed828] VectorSupport::allocate_vector_payload(InstanceKlass*, int, BasicType, frame*, RegisterMap*, ObjectValue*, JavaThread*)+0x41
> 
> 
> The root cause is `VectorSupport::allocate_vector_payload` assumes the
>  `ScopeValue` which denotes the field value generated by C2 compiler
>  is a vector or an oop. But after the vector's payload is changed to be
>  the `MultiField` annotated field, the non-static fields of the vector
>  class is changed to be a series of fields with the same primitive type.
>  In C2 compiler, operations for such multi-fields can be vectorized only
>  if the running hardware supports the vector operations for the specified
>  vector size. For such cases, the field value generated by C2 is a vector.
>  Otherwise, the fields are the scalarized primitive type values. Hence
>  the re-materizalization for such vector objects should be handled just
>  like other normal objects.
> 
> To make things right when re-materializing vector objects whose fields
>  are not vectorized, two parts need to be modified:
> 
> 1. In c2 compiler, pass the un-vectorized multi-fields on safepoint when
>  scalaring an `InlineTypeNode`. To try to vectorize the multi-fields in
>  compiler, only the multi-field base is added to the klass's non-static
>  field list. And the other multi-fields are saved in a secondary field list
>  of their multi-field base. So if the multi-fields are not vectorized, all
>  the field members should be found out and passed to the safepoint.
> 
> 2. During deoptimization, re-materialize the vector objects with different
>  routines based on the `ScopeValue` types. That is, go to the `VectorSupport`
>  routine to re-allocate the objects from a vector value, while go to the
>  normal objects re-allocation path if the field value is not a vector.

Since this issue is fixed by https://github.com/openjdk/valhalla/pull/866 which has been merged, close this PR now.

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

PR Comment: https://git.openjdk.org/valhalla/pull/863#issuecomment-1608938948