RFR: 8335536: Fix assertion failure in IdealGraphPrinter when append is true

[Tobias Hartmann]

On Tue, 2 Jul 2024 09:31:32 GMT, Qizheng Xing <qxing at openjdk.org> wrote:

> When `IdealGraphPrinter` is created with `append` set to true, it does not write the head element to the file in its constructor. But in the destructor, it always writes the tail element to the file no matter `append` is true or not, which causes an assertion failure in `xmlStream::pop_tag`.
> 
> This issue can be reproduced by calling `igv_append` directly, or by calling `Compile::igv_print_method_to_file` with `append` set to true.
> 
> This patch fixes the issue.

src/hotspot/share/opto/idealGraphPrinter.cpp line 920:

> 918:       end_method();
> 919:       begin_method();
> 920:     }

Could you explain this change and maybe add a comment?

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PR Review Comment: https://git.openjdk.org/jdk/pull/19986#discussion_r1663532366