RFR: 8280541: remove self-recursion of ConnectionGraph::find_inst_mem() [v2]

[Xin Liu]

On Wed, 2 Feb 2022 07:12:47 GMT, Xin Liu <xliu at openjdk.org> wrote:

>> This is a follow-up task of JDK-8276219.
>> 
>> ConnectionGraph::find_inst_mem() contains a self-recursion for MergeMemNode.
>> It drills down into one input of MergeMemNode and tries to locate the memory node
>> which has the exact alias_idx. Once it returns, the result won't change from
>> recursion. Therefore, it's not necessary to use recursion in this case. We can
>> reset the initial state of this function and respin.
>> 
>> We can use a collection to remember all MergeMem Nodes and update them after then. 
>> 
>> This patch also makes a cleanup in MergeMemNode::memory_at(). C is not in use in
>> that function.
>
> Xin Liu has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add an assertion in debug build.
>   
>   This patch ensures the result is same as recursion.

@

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PR: https://git.openjdk.java.net/jdk/pull/7204