RFR: 8327963: C2: fix construction of memory graph around Initialize node to prevent incorrect execution if allocation is removed [v8]

[Roberto Castañeda Lozano]

On Wed, 4 Jun 2025 09:23:24 GMT, Roland Westrelin <roland at openjdk.org> wrote:

> > In the common case where allocations are not eliminated, matching transforms the introduced `NarrowMemProj` nodes into a sequence of redundant, raw `MemProj` nodes, see e.g. B6 here: [after-gcm.pdf](https://github.com/user-attachments/files/20477560/after-gcm.pdf). Would it be possible to clean them up during matching (or perhaps already during, or right after, macro expansion)?
> 
> Thanks for looking at this @robcasloz I made the change you requested.

Thanks, will run some testing and come back with the results.

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PR Comment: https://git.openjdk.org/jdk/pull/24570#issuecomment-2940179798