RFR: 8263591: Two C2 compiler phases with the name "after matching"

[Nils Eliasson]

On Tue, 16 Mar 2021 11:24:37 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

> [JDK-8223347](https://bugs.openjdk.java.net/browse/JDK-8223347) added a `PHASE_AFTER_MATCHING` which is equivalent to  `PHASE_MATCHING` but only printed at level 3 and before node verification: 
> https://github.com/openjdk/jdk/blob/20297a1bebfe03c45344a713ec561c97888c4750/src/hotspot/share/opto/compile.cpp#L2757-L2769
> 
> I don't think there is any benefit in having both and therefore removed it together with some other dead code (`idx` is always `0`).
> 
> Thanks,
> Tobias

idx is always 0 from the current source, but I use it a lot when developing. I usually add a print_method for every transformation of something, and adding the idx so it is quick to pinpoint in IGV.

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PR: https://git.openjdk.java.net/jdk/pull/3026