RFR: 8353842: C2: Add graph dumps before and after loop opts phase [v3]

[Manuel Hässig]

On Tue, 8 Apr 2025 14:10:42 GMT, Manuel Hässig <duke at openjdk.org> wrote:

>> This PR adds graph dumps before and after loop optimizations, but only if the compiled method actually contains loops. This helps to distinguish loop optimizations in IGV and to match loop related nodes like opaque template assertion predicates.
>> 
>> I tested this by compiling a few test methods and looking at the ideal graph. Also, I ran tier1 through tier3 and Oracle internal testing.
>
> Manuel Hässig has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix capitalization

Thank you for the reviews!

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PR Comment: https://git.openjdk.org/jdk/pull/24509#issuecomment-2791767407