[jdk17] RFR: 8269088: C2 fails with assert(!n->is_Store() && !n->is_LoadStore()) failed: no node with a side effect [v2]

[Nils Eliasson]

On Tue, 29 Jun 2021 14:10:52 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> In PhaseIdealLoop::try_sink_out_of_loop(), a Store is not expected to
>> be a candidate for sinking: if a Store is in a loop, there has to be
>> at least a memory Phi keeping the Store in the loop. In the case of
>> the failure, a Store has control set in a loop but the Store is not
>> connected to a loop memory Phi. The reason for that is that the Store
>> was moved out of loop by PhaseIdealLoop::try_move_store_after_loop()
>> which moved the Store to the lca of its uses (other than the loop
>> Phi), in this case another loop.
>> 
>> It doesn't look right that a Store is removed from a loop only to be
>> added to another one so I propose fixing that by placing the Store
>> right out of the loop it's being moved out of (similar to
>> PhaseIdealLoop::try_sink_out_of_loop()) rather than at the lca of
>> uses.
>
> Roland Westrelin has updated the pull request incrementally with one additional commit since the last revision:
> 
>   comment

Marked as reviewed by neliasso (Reviewer).

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PR: https://git.openjdk.java.net/jdk17/pull/133