RFR: 8308660: C2 compilation hits 'node must be dead' assert [v2]

[Andrey Turbanov]

On Thu, 14 Mar 2024 16:02:12 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> In `IfNode::fold_compares_helper()`, `adjusted_val` is:
>> 
>> 
>> (SubI (AddI top constant) 0)
>> 
>> 
>> which is then transformed to the `top` node. The code, next, tries to
>> destroy the `adjusted_val` node i.e. the `top` node. That results in
>> the assert failure. Given We're trying to fold 2 ifs in a dying part
>> of the graph, the fix is straightforward: test `adjusted_val` for top
>> and bail out from the transformation if that's the case.
>
> Roland Westrelin has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix test

test/hotspot/jtreg/compiler/c2/TestFoldIfRemovesTopNode.java line 64:

> 62:         if (flag) {
> 63:             k = new int[k].length;
> 64:             int  j = k + 3;

Suggestion:

            int j = k + 3;

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PR Review Comment: https://git.openjdk.org/jdk/pull/18305#discussion_r1527142590