RFR: 8255245: C1: Fix output of -XX:+PrintCFGToFile to open it with visualizer [v2]

[Xin Liu]

On Mon, 26 Oct 2020 12:46:22 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> [JDK-8251093](https://bugs.openjdk.java.net/browse/JDK-8251093) introduced some improved logging for intervals. When specifying `-XX:+PrintCFGToFile` to dump the graph to a file to later open it with the C1 visualizer, it also uses the improved interval printing. However, this output can no longer be read by the C1 Visualizer. As the C1 Visualizer is not part of the JDK, we should include the old format again for the output produced by `-XX:+PrintCFGToFile` to be compatible with the visualizer again. The console output can still use the improved logging of JDK-8251093.
>
> Christian Hagedorn has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Move print_on definition to header file

Marked as reviewed by xliu (no project role).

src/hotspot/share/c1/c1_LinearScan.hpp line 641:

> 639:   }
> 640:   // Special version for compatibility with C1 Visualizer.
> 641:   void print_on(outputStream* out, bool is_cfg_printer) const;

then why not just print_on(outputStream* out, bool is_cfg_printer=false) const directly? those 3 lines can be further saved. :)

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PR: https://git.openjdk.java.net/jdk/pull/837