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

[Xin Liu]

On Tue, 27 Oct 2020 15:57:10 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> 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. :)
>
> This would be a good idea but unfortunately that does not compile as it complains that `virtual void AllocatedObj::print_on(outputStream*) const` was hidden.

you are right.  I just figure out that print_on(outputStream*) const is virtual.  we can't use that trick.  
anyway, your patch looks good to me.

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