RFR: 8355970: C2: Add command line option to print the compile phases

[Christian Hagedorn]

On Mon, 12 May 2025 13:40:54 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

> Thanks for working on the Manuel, looks very useful! Have you considered using the Unified Logging (UL) instead of creating a new JVM flag for this? We already have `-Xlog:jit+compilation` that seems related to this. You might print the compile phase information with e.g. `-Xlog:jit+compilation=trace`, or add a new UL tag if necessary.
> 
> We want to move towards using the UL framework in the JVM compiler components, now that the preparation work by @anton-seoane is completed.

UL is definitely the long-term solution. But given that we have more levels with this new flag (-1 to 6) than UL provides (trace, info, etc.), how could we do it with UL?

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PR Comment: https://git.openjdk.org/jdk/pull/25183#issuecomment-2875160148