[lworld] Integrated: 8315745: [lworld] "Meet Not Symmetric" failures

[Tobias Hartmann]

On Tue, 31 Oct 2023 18:11:36 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

> The following two independent issues showed up with stress testing.
> 
> 
> === Meet Not Symmetric ===
> t   =                   not flat:not null free:narrowoop: java/lang/Object:BotPTR *[int:0..max-2] (java/lang/Cloneable,java/io/Serializable):NotNull:exact *
> this=                   flat:not flat:not null free:top[int:0..max-2] (java/lang/Cloneable,java/io/Serializable):AnyNull:flat(+bot):null_free *,iid=top (inline_depth=1)
> mt=(t meet this)=       not flat:not null free:narrowoop: java/lang/Object:BotPTR *[int:0..max-2] (java/lang/Cloneable,java/io/Serializable):NotNull:exact *
> t_dual=                 stable:flat:narrowoop: java/lang/Object:TopPTR *,iid=top (inline_depth=InlineDepthTop)[int:max-2..0] (java/lang/Cloneable,java/io/Serializable):AnyNull:exact:flat(+top):null_free *,iid=top (inline_depth=InlineDepthTop)
> this_dual=              stable:bottom[int:max-2..0] (java/lang/Cloneable,java/io/Serializable):NotNull * (inline_depth=-1)
> mt_dual=                stable:flat:narrowoop: java/lang/Object:TopPTR *,iid=top (inline_depth=InlineDepthTop)[int:max-2..0] (java/lang/Cloneable,java/io/Serializable):AnyNull:exact:flat(+top):null_free *,iid=top (inline_depth=InlineDepthTop)
> mt_dual meet t_dual=    stable:flat:narrowoop: java/lang/Object:TopPTR *,iid=top (inline_depth=InlineDepthTop)[int:max-2..0] (java/lang/Cloneable,java/io/Serializable):AnyNull:exact:flat(+top):null_free *,iid=top (inline_depth=InlineDepthTop)
> mt_dual meet this_dual= stable:bottom[int:max-2..0] (java/lang/Cloneable,java/io/Serializable):NotNull * (inline_depth=-1)
> 
> 
> The problem is that `mt_dual meet this_dual != this_dual` with `mt_dual->_field_offset == TOP` and `this_dual->_field_offset == TOP` because the `_field_offset` of the result is `BOTTOM`. The fix is to adjust the code in `TypeAryPtr::xmeet_helper` to not set the field offset from `TOP` to `BOTTOM`.
> 
> 
> === Meet Not Symmetric ===
> t   =                   stable:flat:not null free:narrowoop: java/lang/Object:TopPTR *,iid=top (inline_depth=InlineDepthTop)[int:max..0] (java/lang/Cloneable,java/io/Serializable):AnyNull:flat(+top):null_free *,iid=top (inline_depth=InlineDepthTop) (speculative=stable:flat:not null free:narrowoop: java/lang/Object:TopPTR *,iid=top (inline_depth=InlineDepthTop)[int:max..0] (java/lang/Cloneable,java/io/Serializable):AnyNull:flat(+top):null_free *,iid=top (inline_depth=InlineDepthTop))
> this=                   stable:flat:not flat:not null free:narrowoop: java/lang/Object:TopPTR *,iid=top (inline_depth=InlineDe...

This pull request has now been integrated.

Changeset: d5a1584e
Author:    Tobias Hartmann <thartmann at openjdk.org>
URL:       https://git.openjdk.org/valhalla/commit/d5a1584e18782926b941ebe19d8d00f5fa8736de
Stats:     14 lines in 1 file changed: 8 ins; 1 del; 5 mod

8315745: [lworld] "Meet Not Symmetric" failures

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PR: https://git.openjdk.org/valhalla/pull/943